Đồ án tốt nghiệp trong ngành Cơ điện tử liên quan đến việc nghiên cứu, thiết kế và chế tạo máy rửa giấy nhám bằng sóng siêu âm đã được thực hiện với mục tiêu cải thiện quá trình sản xuất và chất lượng sản phẩm trong ngành gỗ. Máy rửa giấy nhám này được thiết kế đặc biệt để áp dụng công nghệ sóng siêu âm, giúp loại bỏ hiệu quả bụi bẩn, tạp chất và các vết bám trên bề mặt giấy nhám. Sự kết hợp giữa cơ điện tử và công nghệ sóng siêu âm trong thiết kế máy giúp tối ưu hóa quy trình làm sạch và nâng cao hiệu suất làm việc của máy, đồng thời giảm thiểu tác động đến môi trường. Đồ án này đòi hỏi việc nghiên cứu sâu về cơ điện tử, sóng siêu âm và quy trình sản xuất giấy nhám. Quá trình chế tạo máy bao gồm việc lựa chọn các linh kiện chất lượng cao, thiết kế mạch điều khiển, cơ cấu hoạt động của máy và tích hợp hệ thống điều khiển tự động. Kết quả dự kiến của đồ án này là một máy rửa giấy nhám hoạt động hiệu quả, tiết kiệm năng lượng, và giảm thời gian sản xuất. Sự ứng dụng của sóng siêu âm trong quy trình rửa giấy nhám không chỉ cải thiện chất lượng sản phẩm cuối cùng mà còn tạo điều kiện thuận lợi cho việc chế tạo hàng loạt trong ngành công nghiệp gỗ. Tóm lại, đồ án tốt nghiệp này tập trung vào việc ứng dụng công nghệ sóng siêu âm trong thiết kế và chế tạo máy rửa giấy nhám, mang lại sự cải tiến đáng kể cho quy trình sản xuất và chất lượng sản phẩm trong ngành gỗ.
OVERVIEW
Topic necessity
The depletion of natural resources and escalating environmental pollution are严重威胁我们的生活环境，导致多种危险疾病。面对这些挑战，国家纷纷调整发展战略，强调经济增长必须与环境保护并重。推动绿色、清洁和循环经济成为实现可持续发展的关键途径，以保障资源可持续利用、减少污染，并促进生态平衡和经济繁荣的共同实现。
The concept of a circular economy was first used formally by Pearce and Turner
(1990) [1] It is used to refer to a new economic model based on the basic principle of
The concept that "everything is an input to another" represents a fundamental shift from the traditional linear economy model Unlike linear systems, this approach emphasizes a circular, regenerative process The Ellen MacArthur Foundation defines this as an industrial system designed to restore or regenerate resources intentionally, promoting sustainability and reducing waste through innovative design.
Accordingly, not only reducing dependence on resources and limiting emissions, Circular Economy models still bring great benefits and promote
Reliable cleaning equipment is essential in today's industrial, medical, and civil sectors to ensure high-quality, efficient operations Traditional cleaning methods, such as manual scrubbing and chemical solutions, often fail to achieve thorough cleanliness, especially for complex parts laden with dirt and grime Relying on manual cleaning with bare hands also increases the risk of introducing unsanitary elements, which can compromise hygiene and make it more difficult to reach the desired level of cleanliness.
Electrolysis cleaning is a widely used method in the plating industry due to its simplicity and ease of use However, it is energy-intensive and may cause surface damage or corrosion of the parts if used for extended periods.
High-pressure water spray cleaning is widely used across various industries due to its ease of use However, it may struggle to thoroughly clean parts with rough surfaces, as the high-pressure water often cannot reach all the nooks and crannies This limitation can reduce its overall effectiveness in achieving comprehensive cleanliness.
Ultrasonic cleaning technology has emerged as an efficient solution for modern industrial equipment, offering fast and high-efficiency cleaning that surpasses traditional methods Despite its advantages, ultrasonic cleaning still faces limitations related to cost and availability, making it a valuable but sometimes inaccessible option for certain applications.
Statistics indicate that manual cleaning leaves approximately 70% of dirt on surfaces, whereas electrolysis cleaning reduces surface impurities by about 50% Meanwhile, high-pressure water spray cleaning is highly effective, capable of eliminating a significant percentage of dirt, making it a superior method for thorough surface cleaning.
20% of dirt In contrast, ultrasonic cleaning can remove less than 5% of dirt, making it highly desirable for achieving optimal cleanliness
Our team is dedicated to researching and developing ultrasonic cleaning technology specifically for the woodworking industry, harnessing its numerous benefits We focus on innovative methods to effectively remove wood chips from sandpaper, addressing the limitations of traditional cleaning techniques Our goal is to improve cleaning efficiency and deliver reliable, effective solutions that meet industry cleanliness standards.
Scientific purpose and practical significance of the topic
In today's eco-conscious world, there is an increasing demand for environmentally-friendly cleaning technologies that prioritize human health Ultrasonic cleaning equipment has become the industry standard due to its effective and sustainable approach Ultrasonic sandpaper cleaning machines are replacing traditional chemical-based methods, offering a greener alternative that minimizes environmental impact and enhances safety By harnessing ultrasonic energy, these machines deliver superior cleaning results, especially for small and complex-shaped items, making them the preferred choice for modern industries seeking efficient and eco-friendly solutions.
Ultrasonic wave technology extends beyond cleaning applications, offering vital uses in quality control, crack detection, and ultrasonic welding Its versatility holds significant potential for development across numerous industries, enabling improved product safety, durability, and manufacturing efficiency Exploring ultrasonic technology is a crucial first step for our research team to gain valuable insights and experience, ultimately paving the way for innovative advancements and practical integration in various fields.
Research objectives of the topic
Cleaning equipment is essential in industrial, medical, and civil fields, prompting extensive research and development Our team aims to leverage our expertise in STM32 programming and SOLIDWORKS design to develop innovative sandpaper cleaning machines integrated with ultrasonic technology These machines will meet necessary technical standards while maintaining cost-effectiveness, offering an efficient solution for mass cleaning applications This approach aims to improve cleaning processes and make advanced cleaning technology more accessible for everyday use.
We will utilize our fundamental electronic knowledge to design safe and efficient circuits with appropriate capacity for the sandpaper cleaning machine The machine comprises three key components: the manufacturing of the sink, the development of the power amplifier circuit, and the creation of control software that displays real-time temperature and operation time, ensuring optimal performance and safety during machine operation.
This project utilizes coarse sandpaper designed for rough sanding, featuring a durable, hard surface suitable for heavy material removal The sandpaper's robust surface quality ensures it maintains functionality even after multiple recycling processes, making it a cost-effective choice for demanding sanding tasks.
Subjects and scope of research
• Conducting a thorough examination of the ultrasonic cleaning machines available in the current market
• Investigating the suitable types of sandpaper that can effectively complement the cleaning capabilities of the machine
• Delving into the structure, operational principles, and synthesis of cleaning machine theories that utilize ultrasonic waves
• Creating a power circuit design that aligns with the machine's capabilities and theoretical knowledge acquired
• Choosing an appropriate frequency that matches with the design requirements and understanding the impact of frequency on cleaning effectiveness
• Gathering information from scientific research conducted both domestically and internationally, examining previously published works in various scientific journals and references from documents, articles, and textbooks
• The sandpaper cleaning machine has a capacity of 8-10 liters and utilizes an ultrasonic wave generator operating at a frequency of 40Khz with a power capacity of 60W
The control system utilizes an STM32 microcontroller to deliver precise functionalities, including timer display and countdown, temperature monitoring and regulation, and motor control along the X-axis, ensuring efficient and accurate operation.
Research Methods
Collecting data from sources such as books, scientific articles, journals and documents from the Internet
Researching methods from experiment and practice
Surveys, interviews, observations, and secondary data analysis
Outline of the graduation thesis
Chapter 4: Design Of Mechanical System
Chapter 5: Design Of Electrical And Control System
Chapter 6: Experiment Results/ Findings And Analysis
Chapter 7: Conclusion And Future Development
The contents of the chapters are as follows:
This chapter provides an overview of the research topic, the objectives, the limitations, and the direction that the research must follow
This chapter covers the fundamental principles of ultrasonic waves and their applications, including the functionality of ultrasonic transducers used in cleaning processes An overview of sandpaper in the woodworking industry highlights its importance in surface finishing, while current cleaning methods provide context for ultrasonic cleaning advantages Factors influencing the ultrasonic cleaning process are examined to optimize efficiency and effectiveness The chapter also reviews various types of ultrasonic cleaning machines available on the market, emphasizing their features and suitability for different applications Additionally, an introduction to the STM32 microcontroller and pulse transformers explains their roles in controlling and enhancing ultrasonic cleaning systems.
This chapter covers the technical requirements of ultrasonic cleaning machines, including the transmission mechanism and machine design, as well as material selection based on their advantages and disadvantages
Chapter 4: Design Of Mechanical System
This chapter discusses the axes of the ultrasonic cleaning machine and the calculations related to material selection and travel distance when implementing the construction of these axes
Chapter 5: Design of Electrical and Control Systems outlines the essential steps for constructing electrical circuits, developing algorithm flowcharts, and providing user instructions It emphasizes testing the operational performance of each functional block through specific performance parameters at every stage to ensure system reliability and efficiency.
Chapter 6: Experiment Results/ Findings And Analysis
This chapter presents the achieved results, observations regarding the strengths, weaknesses, and evaluation compared to the objectives of the topic
Chapter 7: Conclusion And Future Development
This chapter presents the research conclusions of the topic and proposes development solutions for the project.
THEORETICAL BASICS
The overview of wave
Waves are the transmission of energy-carrying signals through an elastic medium, such as solids, liquids, or gases, but they cannot propagate in a vacuum Ultrasonic waves are a type of longitudinal wave that oscillate in the same direction as their movement, making them essential in various applications Sound waves are produced by vibrating objects and travel through a medium, facilitating the transfer of sound energy.
Sound waves produce pressure changes within a medium, causing cyclical increases and decreases in pressure during each wave cycle These pressure variations generate the mechanical effects of ultrasound, making sound waves fundamentally mechanical waves Key characteristics of sound waves include frequency, wavelength, density, and compression, which influence their behavior and application in various fields.
Elastic mediums such as gases, liquids, and solids can be seen as continuous mediums composed of interconnected elements In their equilibrium state, each element maintains a stable position [1]
When a force acts on an element within an elastic medium, it causes the element to deviate from its stable position, initiating oscillatory motion This interaction with neighboring elements results in one side being pulled back toward its equilibrium while the other side is influenced by the force, leading to vibrations These repeated vibrations propagate through the medium as mechanical or sound waves, transmitting energy via the oscillating motion of material elements Overall, a wave is a physical phenomenon that transports energy through the oscillations of particles within the transmitting medium.
Figure 2.2 Classify sound waves by frequency
Sound waves are vibrations transmitted through particles in solids, liquids, and gases, all of which are elastic mediums These waves are elastic waves that propagate through such media, indicating that any elastic body can carry sound waves.
Depending on the frequency band, people divide elastic waves into the following regions:
- Infrasound region: Frequencies below 20Hz (typically not audible to humans)
- Audio frequency range: Frequencies from 20Hz to 20kHz (the range of frequencies audible to humans)
- Ultrasonic range: Frequencies above 20kHz (typically used for applications beyond human hearing, such as medical imaging, cleaning, and measuring)
- Radio frequency range: Frequencies above 100MHz
So ultrasonic waves are from 20kHz to 100MHz Although they have the same nature as an elastic wave, they have different applications due to their different frequencies
• Based on the oscillation of particles in relation to the direction of wave propagation in the medium, ultrasonic waves are classified into longitudinal waves and transverse waves
• Longitudinal waves: These are oscillations of particles parallel to the direction of wave propagation
• Transverse waves: These are oscillations of particles perpendicular to the direction of wave propagation
Ultrasonic waves carry significantly more energy than audible sound waves; for instance, at the same amplitude of oscillation, a wave at 1MHz possesses a million times greater energy than one at 1kHz This substantial energy difference makes ultrasonic waves particularly effective for applications requiring high energy transfer, such as medical imaging and industrial cleaning Understanding the energy disparity between ultrasonic and sound waves is essential for optimizing their use across various technological fields.
Ultrasonic waves, with their shorter wavelengths in the same medium of wave propagation, exhibit high directional properties, allowing wave energy to travel in a focused, specific direction This characteristic enables the design of converging systems that concentrate large amounts of energy into a narrow area, enhancing precision and effectiveness in applications such as medical imaging and industrial inspection.
• Within the ultrasonic frequency range and under specific conditions, the phenomenon occurs wave penetration occurs in liquids This property finds extensive applications in industries and daily life
Figure 2.4 Rarefaction and Compression in Longitudinal Wave
The frequency of a mechanical wave refers to the rate at which atoms in the medium oscillate, indicating the number of wave cycles occurring per second Measured in Hertz (Hz), symbolized as "f," wave frequency is a key parameter that determines the wave's characteristics and behavior during propagation.
The wavelength (λ) represents the distance a wave travels during one complete cycle (T), serving as a key parameter in wave physics When atoms are spaced at specific intervals, they oscillate in sync with each other, maintaining the same phase as the wave propagates through the medium Understanding the relationship between wavelength and atomic separation is essential for comprehending wave behavior and energy transfer.
The rate at which energy is transferred between two points in a medium due to wave motion is called the wave velocity (v)
D Absorption of ultrasonic waves by the transmitting medium:
Wave propagation in a medium results in a gradual decrease in wave intensity due to absorption and scattering, with energy attenuation influenced by factors such as thermal conductivity, friction coefficient, and medium inhomogeneity Additionally, the frequency of the wave plays a significant role in the extent of absorption The overall wave absorption can be quantified using a general formula, expressed as α = 4ρ²f², which highlights the dependence of attenuation on both material properties and wave frequency.
E Acoustic Impedance of the Medium:
The acoustic impedance of a medium, also known as the sound reflection or sound density of the medium, is determined by the equation:
V is the velocity of sound propagation in the medium (m/s)
ρ is the mass density of the medium (Kg/m3)
Z represents the acoustic impedance of the medium (Rayls)
Therefore, the total acoustic impedance is a parameter that depends on the transmitting medium
Ultrasonic wave velocity is directly proportional to the material's compression level, meaning that the harder a material is to compress, the faster the ultrasonic waves travel through it In solid materials, increased hardness and density promote higher wave speeds, while in gases, the wide molecular spacing results in weaker intermolecular bonds This causes ultrasonic waves to propagate more slowly in gases, as molecules need to travel longer distances between interactions, reducing overall wave velocity Understanding the relationship between material compression and ultrasonic wave speed is essential for applications like material testing and nondestructive evaluation.
In liquid and solid mediums, molecules are closely packed, forming stronger intermolecular bonds This proximity allows particles to interact with their neighbors over shorter distances, which increases the velocity of wave propagation through these materials.
Materials with high density are usually made up of larger particles, which possess greater inertia and are more resistant to displacement and stopping As a result, higher-density materials tend to exhibit lower wave velocities due to their particle size and inertia Understanding this relationship is essential in applications requiring precise control of wave propagation through different materials.
In a liquid medium, density and compression are usually inversely proportional, resulting in similar wave propagation velocities
In solids, the compression is often much greater than the density, leading to higher wave propagation velocities
H Sound Pressure and Sound Intensity:
Sound pressure is a characteristic quantity that represents the cyclic variation in stress within a material caused by the propagation of ultrasonic waves Sound pressure is expressed by the formula:
f represents the frequency of the sound wave,
a represents the amplitude of the sound wave
Sound intensity is the measure of sound energy transmitted per unit of time and area, reflecting the strength of the sound received It is directly related to sound pressure, which influences how we perceive loudness Additionally, sound intensity can be calculated using parameters like the speed of sound and the density of the medium, providing a comprehensive understanding of sound propagation in different environments.
Both sound pressure and sound intensity play crucial roles in the study and analysis of ultrasonic waves and their effects on materials and environments.
Overview about sandpaper
Sandpaper is a versatile abrasive material used across industries and DIY projects for smoothing, polishing, and shaping surfaces It features a backing made of paper or cloth, coated with abrasive particles such as aluminum oxide, silicon carbide, or garnet These mineral abrasives define the sandpaper’s cutting efficiency and finish quality, making it essential for achieving professional results in surface preparation and refinement.
Sandpaper grit size indicates the number of abrasive particles per inch of the backing material Coarse grits with lower grit numbers feature larger abrasive particles, making them ideal for rough sanding and removing material quickly Conversely, fine grits with higher grit numbers contain smaller particles, perfect for fine finishing and polishing tasks Understanding sandpaper grit sizes helps achieve the desired surface quality effectively.
Sandpaper grit, also known as its abrasive grade, indicates the size and coarseness of the abrasive particles on its surface Manufacturers use grit values to categorize and differentiate their products in the market, ensuring users select the appropriate sandpaper for their specific tasks Understanding sandpaper grit helps achieve desired surface finishes, whether for rough material removal or fine polishing.
Higher grit sandpapers, such as emery paper and sanding cloth rolls, feature sharper abrasive particles, resulting in faster sanding action However, it's important to choose the appropriate grit level for your specific project, as not all tasks require high-grit sandpaper Selecting the right sandpaper ensures effective results and prevents unnecessary material removal.
Choosing the right grit is essential and depends on the material of the surface to be sanded and the desired finish Selecting the appropriate grit ensures effective results tailored to your specific project requirements.
When selecting a sandpaper product, you'll notice symbols such as the letters A or P on the packaging or the product itself, indicating the grit value These symbols help identify the abrasive's coarseness, with A and P designations representing different grit standards Understanding these markings ensures you choose the appropriate sandpaper for your specific sanding needs, whether for coarse grinding or fine finishing.
P: is the grit symbol according to the European standard (FEPA, the European Federation of Abrasives Producers)
A: is the grit symbol according to the Japanese standard (JIS, the Japanese Industrial Standards)
Sandpaper grit is usually indicated by numerical designations like P40, P120, and P240, where lower numbers correspond to coarser abrasiveness and higher numbers denote finer grit Selecting the appropriate grit ensures efficient polishing and optimal results across various materials Proper grit choice is essential for achieving a smooth finish and preventing damage during sanding tasks.
Sandpaper is classified based on its function and grit
Sheet Sandpaper: Specifically designed for use by hand or with vibrating hand sanders, it comes in dimensions of 230 x 280 mm and is commonly used in PU painting technology
Roll Sandpaper: Specially used for handheld sanders (orbital sanders, belt sanders) with a width of less than 300 mm
Belt Sandpaper: Specifically used for wide belt sanders with widths of 600, 900, or 1300 mm, often applied in the woodworking industry
The grit of sandpaper indicates the level of smoothness it can achieve on a surface after sanding Selecting the appropriate grit is essential and depends on the specific task at hand Using the right grit ensures optimal results, whether you’re removing rough edges or achieving a fine, polished finish.
Currently, sandpaper is classified according to grit as P40, P80 (for relatively coarse grit), P180 (for PU primer), P240 (for PU finishing), P320 (for high smoothness), and P400 (for very high smoothness)
Figure 2.6 Sandpaper selection chart based on grit
When using sandpaper, we need to pay attention to the following points:
* Choose the right type of sandpaper according to the purpose and usage needs
* Equip yourself with proper protective gear such as gloves, masks, goggles, ear protection,…to minimize accidents and risks
Proper installation of sanding machines is essential for safe operation; ensure all joints are precisely fitted and securely tightened to prevent parts from detaching, thereby reducing safety hazards for users and nearby individuals.
Figure 2.7 Using Sandpaper in Woodworking
2.2.4 Application of sandpaper in woodworking:
Sandpaper is a vital tool used extensively in woodworking for various applications
Sandpaper is made up of abrasive particles bonded to a paper or cloth backing, and it is available in various grit sizes from coarse to fine It is commonly used in woodworking for smoothing surfaces, removing rough spots, and preparing wood for finishing Proper grit selection is essential for achieving a high-quality finish and ensuring efficient work.
Sandpaper is primarily used to smooth wood surfaces by eliminating rough spots, tool marks, and uneven areas after initial shaping and cutting, ensuring a polished and even finish.
Proper surface preparation is essential before applying finishes like paint, stain, or varnish on wood Sanding with sandpaper ensures a smooth, uniform surface, which enhances the adhesion of the finish and results in a professional-looking final product.
• Removing Imperfections: Sandpaper is an effective tool for removing minor imperfections in the wood, such as scratches, dents, and blemishes It helps in restoring the wood's appearance and prepares it for finishing
• Contouring and Shaping: Different grits of sandpaper can be used to shape and contour wood Coarse grits are suitable for initial shaping, while finer grits allow for precise detailing and shaping of intricate woodwork
• Smoothing End Grain: Sandpaper is especially useful for smoothing the end grain of wood, which tends to be rough and porous Properly sanding the end grain helps achieve a more consistent and attractive finish
Cleaning Technology
Cleaning is a daily task that we all regularly face In a broader sense, it involves removing unwanted and complicated substances from the surfaces of devices and components [2]
Cleaning methods vary, with traditional manual techniques like immersing equipment in cleaning solutions that leverage both chemical and mechanical effects This approach typically involves using brushes or brooms to clean simple, flat, and smooth surfaces However, it is less effective for tight or hard-to-reach areas, making it suitable mainly for accessible surfaces.
Quick and simple cleaning process that does not require advanced technology
Ineffective for cleaning devices with complex structures or narrow gaps
Surface scratching due to the use of brushes or brooms
Surface deformation and structural damage to small and delicate components of the device
Modern industrial production relies on highly efficient manufacturing lines capable of producing millions of identical products annually, demanding high-precision and consistent dimensions to streamline assembly, reduce costs, and save time To maintain optimal cleanliness standards across various stages, ultrasonic cleaning devices are widely integrated into production processes, ensuring surfaces are thoroughly cleaned before further processing This technology is especially vital in manufacturing high-density electronic circuit boards and complex metal components with intricate shapes and multiple holes, where cleanliness, hardness, and precision are critical Ultrasonic cleaning effectively removes dirt and contaminants from detailed surfaces, preparing products for subsequent coating, polishing, and quality assurance steps.
2.3.3 Principles of Cleaning using Ultrasonic Technology:
Ultrasonic waves are waves with frequencies higher than 18kHz, which cannot be heard by humans
Ulasonic cleaning machines typically operate within wave frequencies ranging from 20 kHz to 200 kHz Frequencies between 10 kHz and 50 kHz are commonly used for industrial cleaning applications, such as cleaning medical instruments and items on production lines Higher ultrasonic frequencies above 50 kHz are specialized for cleaning delicate components like optical instruments, biological filter membranes, and dental equipment in hospitals, ensuring thorough cleaning without damage.
The ultrasonic waves in cleaning machines are mechanical waves and possess all the physical properties such as wave propagation, reflection, and wave interference in different transmitting media
When a mechanical wave is generated in air or liquid under pressure, it creates a compressed wave that propagates primarily in the direction of the driving force This wave contains numerous higher frequency components, often described as "bubbles within bubbles," with bubble size influenced by the ultrasonic wave's frequency Higher ultrasonic frequencies produce smaller bubble sizes, affecting the wave's behavior and applications.
Bubbles continuously travel through the liquid medium until they collide with a surface obstruction along the wave path When subjected to the compressive force of the wave, these bubbles rupture, leading to cavitation and the direct shooting of liquid particles onto the object's surface This impact dislodges dirt, debris, and contaminants, effectively cleansing the surface and removing impurities through the negative pressure generated near the liquid surface.
2.3.4 Cleaning Process using Ultrasonic Technology:
When powered, ultrasonic sensors generate high-frequency mechanical wave oscillations above 20,000 Hz, which are transmitted into the stainless steel tank to produce high-frequency shockwaves within the liquid These shockwaves rapidly create and propagate numerous small bubbles throughout the cleaning solution, following the principles of mechanical wave propagation in liquids The moving bubble clusters collide with the surface of the object being cleaned, exerting a mechanical impact that dislodges dirt particles The chemical action of the cleaning solvent then dissolves these particles with ease Additionally, smaller bubbles penetrate deeper into tiny crevices and complex surfaces, making ultrasonic cleaning highly effective for cleaning intricate and hard-to-reach areas that traditional methods struggle to clean.
For effective cleaning, the solution must come into direct contact with dirt particles to ensure they dissolve properly Facilitating this contact is essential, as the cleaning process helps the chemicals interact directly with the dirt, leading to more efficient removal of stains and debris.
When cleaning chemicals dissolve dirt, the chemical layer near the surface of the object gradually becomes saturated, slowing or halting the cleaning process To maintain effective cleaning, it is essential to regularly replenish with fresh cleaning chemicals, ensuring continuous dissolution of dirt and improved cleaning efficiency.
Ultrasonic waves enhance cleaning efficiency by generating bubble waves that impact the surface, disrupting the saturated chemical layer This process allows the active chemical layer to maintain direct contact with the surface, resulting in more effective cleaning.
Dirt particles that are not dissolved but loosely adhere to surfaces do so through ion bonding or cohesive forces These particles can be effectively removed by applying a force greater than their adhesion strength, allowing them to be easily separated from the surface Proper cleaning techniques leverage this principle to ensure thorough removal of surface contaminants.
To achieve high efficiency in ultrasonic cleaning, the cleaning solution needs to wet the dirt particles to be cleaned
Effective ultrasonic cleaning depends on selecting the right cleaning agent, providing sufficient ultrasonic energy, and considering temperature, as different types of dirt may dissolve or remain resistant in the cleaning solution Properly adjusting these factors is essential to optimize surface cleaning performance and achieve thorough cleanliness.
2.3.5 Advantages of Ultrasonic Cleaning Technology:
Unlike other cleaning methods, ultrasonic waves can effectively clean surfaces of objects in any shape by using bubbles that can reach different depths and angles
There are several real benefits from the application of ultrasonic waves in precise cleaning
Ultrasonic cleaning technology offers significantly faster cleaning speeds compared to traditional methods, enabling efficient and thorough cleaning without the need for disassembly This reduces labor costs and enhances productivity, making ultrasonic cleaning the most cost-effective solution for various applications.
Ultrasonic cleaning provides consistent and thorough results, effectively cleaning objects of all sizes and complexities—from single parts to multiple items simultaneously This advanced technology ensures meticulous removal of dirt from all surface areas without relying on the operator, offering a uniform cleaning effect driven by ultrasonic waves.
Safety and environmental compliance by reducing the concentration of hazardous chemicals or replacing corrosive cleaning agents with safer alternatives
Reduces direct contact between the operator and hazardous cleaning agents
Energy-efficient, labor-saving, and cost-effective
Ultrasonic cleaning machines provide real productivity value for precise cleaning applications.
Factors Influencing the Ultrasonic Cleaning Process
2.3.1 Relationship between Frequency and Bubble Size:
Higher frequency ultrasound produces smaller bubbles, which can be generated at shorter distances compared to larger bubbles This correlation between frequency and bubble size is visually demonstrated in the image below, highlighting how increased frequency results in finer bubble foam These insights are essential for optimizing bubble size control in various applications.
Figure 2.13 The relationship between frequency and bubble size
Larger bubble foam in water results from high-intensity cavitation, where bubble implosion is more powerful The size of these bubbles is inversely related to ultrasonic frequency, meaning lower frequencies tend to produce larger bubbles Lower ultrasonic frequencies create waves with longer intervals between bubble formations, allowing bubbles to grow bigger over time Conversely, increasing the frequency leads to a higher number of bubbles, though they tend to be smaller When ultrasonic power remains constant, bubbles formed at lower frequencies are more likely to undergo intense implosion, enhancing cavitation effects Optimizing ultrasonic frequency is crucial for controlling bubble size and cavitation intensity in water treatment, cleaning, and other applications.
Temperature is a crucial parameter for maximizing bubble intensity, as it influences viscosity, gas solubility, gas diffusion rate, and vapor pressure within the liquid Optimal bubble generation in pure water occurs at approximately 160°F (71°C), where these factors align to produce peak bubble formation Adjusting temperature accordingly can significantly enhance bubble production efficiency in various applications.
The viscosity of a liquid plays a crucial role in bubble generation, with lower viscosity leading to reduced bubble formation intensity Most liquids experience a decrease in viscosity as temperature rises, which can impact bubble formation efficiency To optimize bubble generation, the liquid must contain an adequate amount of dissolved gas; this gas is released during bubble formation, helping to prevent bubble implosion However, as temperature increases, the dissolved gas content in the liquid decreases, while the diffusion rate of the gas accelerates, affecting the stability and size of the generated bubbles.
As the temperature of the liquid approaches its boiling point, vapor bubbles are more likely to form These vapor-filled bubbles exhibit decreased intensity, leading to localized evaporation within the tank This process indicates the onset of boiling and is crucial for understanding phase changes in liquids.
The best ultrasonic performance is achieved at around 65% of the liquid's boiling point
Temperatures above 65% of the boiling point will reduce the system's effectiveness
Most ultrasonic cleaning agents use temperatures between 54 and 82°C
When using materials with acidic properties, use the lowest temperature possible to minimize damage to the ultrasonic tank surface
Appropriate temperatures for cleaning objects:
Most industrial parts are best cleaned at temperatures between 50-70°C, especially when cleaning microscope parts
Electrical and electronic components are best cleaned at 45-55°C
Gas-affected objects may require cleaning at higher temperatures, up to 80°C
Objects made of soft and delicate materials with chemical bonding typically only need to be cleaned at room temperature
Laboratory equipment and specialized medical instruments should be cleaned ultrasonically at temperatures between 55-65°C
Choosing the appropriate chemical compounds is crucial for the success of ultrasonic cleaning, as they must be compatible with the metal’s composition and deliver effective cleaning performance Proper selection of chemicals ensures optimal results and prevents potential damage to the cleaned items Using compatible and effective cleaning agents enhances the overall efficiency and reliability of the ultrasonic cleaning process.
Effective ultrasonic cleaning requires chemicals capable of generating strong bubble agitation to enhance cleaning performance Many chemical cleaning agents are specially formulated for ultrasonic technology, ensuring compatibility and ease of use Several common chemicals used in ultrasonic cleaning are listed in the table below, highlighting their suitability for this efficient cleaning method.
Table 2.1 Some common cleaning solutions for metal
Temperature ºC Metal to Clean Application
5-25 g/l 40-50ºC Steel Cleaning dirty parts
40-60ºC Steel Cleaning dirty parts
50ºC Steel Cleaning dirty parts
50ºC Rusty Steel Removing scales and rust
The effectiveness and duration of the cleaning process depend on various factors, including temperature, soil type, chemical concentration, and pulse frequency Typically, cleaning in a tank can take between 10 to 15 minutes, whereas using a high-pressure spray vessel with a quality cleaning agent can achieve results in just a few seconds.
2.3.5 Ultrasonic Power and Tank Volume:
Ultrasonic power is typically expressed in terms of watt per gallon or liter, though manufacturers may describe it differently It refers to the energy transferred to the ultrasonic transducer during cleaning and is measured in watts per volume of cleaning solution For effective ultrasonic cleaning, most agents recommend a power range of 50 to 100 watts per gallon (3.78 liters) to ensure optimal results.
Increasing ultrasonic power enhances the number of bubbles and improves cleaning efficiency, but only up to a specific threshold Exceeding this limit leads to energy waste and potential damage to the cleaned components Optimizing ultrasonic power is essential for effective and safe cleaning processes.
Total power in an ultrasonic tank encompasses the energy needed to operate the entire system, including the ultrasonic generator and the heating system if present It is important to distinguish total power from ultrasonic power alone, as it represents the overall energy consumption required for the complete operation of the ultrasonic process Understanding the difference between these power types helps ensure proper system design and efficiency.
Peak power is defined as the ultrasonic power generated at the peak of the sound wave and can be 2, 4, or 8 times higher than the average power
Ultrasound waves have an important role in various areas of life and are applied in different fields such as medicine, industrial machinery, scientific research, and geographical exploration
Ultrasound technology is central to modern medical applications, significantly enhancing diagnosis, treatment, and patient care It enables early detection of tumors by identifying changes in tissue cell size and sound wave velocity, allowing precise localization and assessment of tumor development Ultrasound is employed in various medical devices, including diagnostic imaging and therapeutic systems, with Doppler ultrasound playing a key role in quickly and accurately detecting internal abnormalities.
Industrial applications of ultrasound waves: Ultrasound is applied for product defect detection, weld quality assessment, and thickness measurement, among other industrial processes
Geographical exploration applications of ultrasound waves: Ultrasound waves are used to survey and map challenging terrains such as deep ocean floors and mountainous regions
Figure 2.16 Survey and map challenging terrains
Ultrasonic welding is a technique that utilizes high-frequency ultrasonic vibrations, typically around 20 kHz, generated by powerful oscillators to soften the workpiece This process involves applying pressure through mechanical or pneumatic means to bond components together, resulting in a strong, atomic-level join Similar to friction welding, ultrasonic welding offers a precise and efficient method for joining thermoplastics and metals without the need for additional adhesives or fasteners.
Ultrasonic cleaning tanks are essential tools used in both industrial and household settings to safely clean items that may be harmful or prone to damage Their effectiveness in cleaning complex components and delicate instruments makes them invaluable across various industries Applications of ultrasonic cleaners include laboratories, hospitals, mineral extraction, and electronic assembly, showcasing their versatility and importance in maintaining cleanliness and safety standards.
Ultrasonic cleaners are highly versatile, used for maintaining and cleaning a variety of items including watches, eyeglasses, jewelry, and electronic devices Additionally, they offer an effective, non-toxic solution for cleaning fruits and vegetables, providing a healthier alternative to traditional cleaning methods.
In summary, ultrasound waves have diverse applications in medical diagnostics, industrial processes, geological exploration, welding, scientific research, and cleaning
These applications contribute to advancements in various fields, leading to improved healthcare, manufacturing efficiency, and scientific understanding
Factors to consider when using ultrasonic cleaning with a cleaning solution:
Roles and Classification of Transducers
An ultrasonic transducer is a device that converts electrical energy into mechanical oscillations at ultrasonic frequencies, enabling various applications in imaging and sensing Conversely, it can also transform mechanical vibrations back into electrical signals, functioning as both a receiver and a transmitter These dual capabilities categorize ultrasonic transducers into receiving and transmitting types, making them essential components in ultrasonic technology.
Ultrasonic electrical oscillations are processed and amplified before being sent to the transmitting transducer The transducer converts these electrical signals into mechanical vibrations that propagate through the medium to achieve a specific function Depending on its construction material, the transducer can be either electrostrictive or magnetostrictive, each offering different performance characteristics for ultrasonic applications.
Electrostrictive transducers typically have low power and operate at high frequency ranges Conversely, magnetostrictive transducers are commonly used in high-power devices and operate at low frequencies [4]
The receiving transducer detects external mechanical vibrations and converts them into electrical signals These electrical signals are then processed and amplified to the appropriate level, providing vital input for measurement, indication, or alerting devices.
Receiving transducers are typically electrostrictive transducers with high sensitivity
Piezoelectric transducers operate based on the piezoelectric effect, discovered by Curie in 1880, where materials like quartz crystals and barium titanate produce mechanical vibrations and alternating electric charges when exposed to an electric field However, these materials often face challenges such as unstable vibrations and limited mechanical load capacity Since the 1940s, American scientists have advanced piezoelectric technology by developing sensors that offer high power output, enhanced durability, and stable frequency response in demanding mechanical and environmental conditions.
Piezoelectric materials generally exhibit a smaller deformation effect compared to magnetostrictive transducers, with oscillation amplitudes ranging from 0.1µm to 7µm Despite their limited deformation, piezoelectric transducers can operate at high frequencies, reaching up to 5MHz This combination of minimal deformation and high-frequency capability makes them suitable for precise applications in various industries.
Magnetostrictive sensors offer significantly higher power output compared to piezoelectric sensors, making them ideal for applications demanding robust performance Piezoelectric sensors excel in energy conversion, effectively transforming electrical, mechanical, and acoustic energies, which enhances their versatility Their compact size makes piezoelectric transducers especially suitable for use in ultrasonic cleaning machines, providing efficient and precise cleaning solutions.
The piezoelectric effect occurs when mechanical force applied to a piezoelectric material causes it to deform and generate an electrical signal Specifically, the direct piezoelectric effect involves the generation of opposite charges on the two surfaces of the material when a force is applied This phenomenon can be demonstrated by attaching electrodes to a quartz plate coated with silver and measuring the resulting deflection of an electrometer needle, highlighting the material's ability to convert mechanical stress into electrical energy.
Applying tensile force to the thin plate causes it to expand, leading to the electrometer needle deflecting to the left and indicating opposite charges on its surfaces Conversely, compressive force results in the plate contracting, with the electrometer needle deflecting to the right, reflecting a reversal in the surface charges These observations demonstrate how mechanical deformation influences charge distribution on the plate, which is essential for understanding electro-mechanical interactions.
Figure 2.19 Direct piezoelectric effect (a) Tension Force (b) Compressive Force
The direct piezoelectric effect occurs when mechanical deformation of a piezoelectric material generates opposite electrical charges on its surfaces This fundamental phenomenon underpins the use of piezoelectric materials in a wide range of applications, including sensors, ultrasound devices, and actuators.
The relationship between the charge Q and the force F is determined by the equation:
Q is the charge in Coulombs
F is the magnitude of the applied force in kilograms
When a mechanical force impacts the surface of a thin plate, it induces mechanical oscillations that generate an alternating electrical signal This electrical signal, which matches the frequency of the mechanical oscillation, appears on the two electrodes of the thin plate, enabling effective detection of mechanical vibrations through electrical means.
Materials that exhibit properties as described above are known as piezoelectric materials
This principle is the basis for constructing piezoelectric sensors for ultrasound wave detection
Connecting two electrodes of a piezoelectric plate to a DC power source causes the material to expand in thickness, while reversing the polarity results in contraction, demonstrating the inverse piezoelectric effect This phenomenon illustrates how applied electric fields induce mechanical deformation in piezoelectric materials, enabling them to convert electrical energy into mechanical strain [6].
The relationship between 𝑙 and the applied voltage V is determined by the equation:
- L is the variation in the geometric dimension of the piezoelectric plate
- K is the piezoelectric constant, which has a value of 6.9 × 10^(-8)
- V is the magnitude of the applied polarizing voltage from the power source
Applying an alternating electrical signal with frequency \(f\) to the surface of a piezoelectric plate causes its thickness to vary continuously at the same frequency This mechanical oscillation generated by the thickness change propagates into the surrounding environment, creating effective vibrations These properties make piezoelectric devices ideal for sensors, actuators, and signal transducers Understanding this relationship between electrical signals and mechanical response is essential for optimizing piezoelectric applications in various industries.
This principle is the basis for constructing ultrasonic transducers
Experiments have shown that the oscillation amplitude of a piezoelectric plate is maximized when the voltage source's frequency matches the plate’s natural oscillation frequency This natural frequency depends on the plate’s material composition and thickness, which can be calculated using a specific equation Optimizing the excitation frequency to coincide with the natural resonance enhances the efficiency and performance of piezoelectric devices Understanding the relationship between material properties, thickness, and natural frequency is crucial for precise piezoelectric system design.
- 𝑓𝑜 is the natural oscillation frequency of the piezoelectric plate
- k is the natural oscillation coefficient (kHzãmm)
- l is the thickness of the piezoelectric plate (mm)
C The structure and shape of an ultrasonic transducer:
Figure 2.21 The structure of an ultrasonic transducer
Magnetostriction is a physical phenomenon where magnetic materials change their dimensions and shape when exposed to a magnetic field This occurs as the interaction between the material's magnetic structure and the magnetic field alters the spacing between atoms or molecules, causing the material to either expand or contract As a result, magnetostriction leads to measurable changes in the size and shape of magnetic materials, making it a key factor in various technological applications.
Connecting both ends of the coil to a DC power source causes the magnetic core to expand, indicating magnetostriction effects Reversing the power supply's direction results in the contraction of the magnetic core, demonstrating the reversible nature of magnetic-induced dimensional changes This phenomenon highlights the relationship between magnetic field polarity and the physical deformation of magnetic cores, essential for understanding electromagnetism and magnetic materials.
Microprocessor STM32
The STM32F103C8T6 features a powerful ARM Cortex-M3 32-bit RISC core operating at 72 MHz, delivering high performance for diverse applications It includes high-speed embedded memory, with up to 128KB of Flash and 20KB of SRAM, enhancing data storage capabilities The microcontroller offers a wide range of enhanced I/Os and peripherals connected via two APB buses, supporting versatile connectivity Notable features encompass two 12-bit ADCs, three 16-bit timers, and a PWM timer, enabling precise control and measurement applications Additionally, it supports various communication interfaces such as I2C, SPI, USART, USB, and CAN, making it suitable for complex embedded system designs.
Figure 2.22 Pin descriptions of STM32
Power 3.3V, 5V, GND 3.3V – Regulated output voltage from the onboard regulator (drawing current is not recommended), can also be used to supply the chip
5V from USB or onboard regulator can be used to supply the onboard 3.3V regulator GND – Ground pins
Pins act as ADCs with 12-bit resolution
Input/output pins PA0 – PA15
UART with RTS and CTS pins
All digital pins have interrupt capability
PA6 – PA10 PB0 - PB1 PB6 – PB9
Inbuilt LED PC13 LED to act as a general- purpose GPIO indicator
Inter-Integrated Circuit communication ports
CAN CAN0TX, CAN0RX CAN bus ports
Figure 2.23 Pin function of STM32
The following applications can benefit from the features offered by the STM32F103C6T8 performance line microcontroller:
- Motor drive and application control
- PC peripherals, gaming platforms, and GPS devices
- Industrial applications such as PLCs, inverters, printers, and scanners
- Alarm systems, video intercoms, and HVAC (heating, ventilation, and air conditioning) systems
Similar products on the market
The CO-Z Ultrasonic Cleaner features a robust construction with reinforced inner tank walls, ensuring long-lasting ultrasonic cavitation that effectively cleans even the tiniest crevices Designed for industrial-grade durability, it offers a minimum 2-year service life that surpasses competitors The digital control panel allows customizable temperature and timer settings, enabling professional-grade cleanliness for a wide range of household and industrial objects For thorough cleaning and dependable safety, the CO-Z Ultrasonic Cleaner is the ultimate choice for both professionals and home users.
The ultrasonic cleaner boasts a 2-liter stainless steel tank, ideal for cleaning larger items or multiple smaller objects simultaneously Equipped with user-friendly digital controls and adjustable timer settings, it allows precise operation tailored to different cleaning needs Operating at a frequency of 40 kHz, this commercially designed machine delivers efficient and thorough cleaning for a wide range of objects.
Tank Capacity: 1.8-2L (Since the bottom of the ultrasonic cleaner is a curved surface, the actual volume will be smaller.)
Time Setting: 0-30 min (LED Digital Display)
DESIGN OPTIONS
Choose machine structure
Based on the technical requirements of the machine, each operating method has its own advantages and disadvantages, depending on the manufacturing needs to choose the appropriate model type
Table 3.1 Advantages and Disadvantages of one cleaning tank and multiple cleaning tanks
There is only one cleaning tank There are multiple cleaning tanks
• Reduced load-bearing capacity of the machine frame
• Applicable on a small scale, for households
•Can clean at different temperatures simultaneously
• Can clean with multiple solvents simultaneously
• Can be dried after cleaning
•Cannot clean with multiple solvents simultaneously
•Cannot clean at different temperatures simultaneously
• Residue of solvents may remain after cleaning
Figure 3.1 Ultrasonic cleaning tank with one basin
Figure 3.2 Ultrasonic cleaning tank with multiple basins
Conclusion: Thus, after evaluating the above two structural options, our group chose ultrasonic washing tank with many tanks.
Choose transmission mechanism
Our team has found the right transmission mechanism option for ultrasonic cleaner: screw drive, pneumatic, hydraulic Here we analyze the advantages, disadvantages of the above 3 options:
Table 3.2 Advantages and disadvantages of transmission mechanism
• Easy and non-invasive operation noise
• Easy to control precise position
• A considerable amount of heat is generated in the actuator, so need lubrication
• The lubrication must be strictly maintained to ensure the life of the shaft
Hydraulics • Strong and fast transmission with high power
• Easy to use and repair
• Use at high speed without fear of strong impact like in case of electric shock
• Suitable for systems requiring large loads (kN)
• When starting up, the temperature of the system is not stable, the working speed will change
• Loss in oil pipelines and leaks inside elements reduce performance and application range
• It is difficult to keep the speed constant when the load changes
• Difficult to achieve 1mm position accuracy (achievable but costly very high)
Pneumatic • Do not pollute the environment
• Capable of transmitting energy far
• Limited pressure prevention system is guaranteed
• Inability to generate great force
• As the load in the system changes, the velocity also changes
• The control is often not very accurate
• Compressed air exits at the inlet
Based on the analysis of the pros and cons, considering the maximum load requirement of 300N and the need for a constant speed while maintaining high positional accuracy, a screw actuator emerges as the optimal solution It offers a cost-effective option that meets the demands for precision and load capacity, making it ideal for applications requiring reliable performance with minimal expense.
Choose material of frame
The choice of frame material is diverse, including steel, aluminum sheets, corrugated iron, aluminum profiles, and wood, each offering different levels of durability and precision Selecting the appropriate material depends on the technical requirements of the project, ensuring factors such as strength, stability, and accuracy are met to optimize machine performance.
• The machine frame must ensure rigidity
• No vibration, shaking during machining
• The machine frame is easy to clean, ensuring aesthetics
• Easy to disassemble and maintain
Materials such as corrugated iron, steel plates, and aluminum plates meet the necessary requirements for chassis construction Selecting the most suitable material depends on factors like strength, durability, and weight, ensuring optimal performance and longevity By analyzing these options, we can determine the best material—whether steel for strength, aluminum for lightweight design, or corrugated iron for cost-effective durability—that aligns with our specific project needs.
Table 3.3 Advantages and disadvantages of material for frame
• Anti-corrosion caused by the environment
• Heat resistant, extremely heat resistant efficiently, durable
• High economic efficiency thanks to affordable price
• Low rust resistance in harsh weather conditions containing corrosive substances
• The surface is easily scratched, affecting aesthetics
Steel plate • Steel plate with high hardness and high strength
• The steel is well-processed, meticulously, with no roughness or ripples
• Unaffected by environmental factors and weather
• Large in size, bulky and difficult to transport transfer
• There should be a separate preservation method for each different type of steel plate
• Aluminum plate has good heat resistance
• Has high chemical resistance, good wear resistance
• Poor durability and bearing capacity
• Specific gravity is lighter than steel
• The surface is smooth, beautiful, easy to process, drill holes, plan grooves
All three materials meet the technical requirements for chassis construction Among them, titanium offers exceptional advantages over steel and aluminum plates However, our team selected aluminum for the chassis design due to its high corrosion and heat resistance, along with a smooth, attractive surface Additionally, aluminum is easy to process, enabling efficient drilling, grooving, and other fabrication tasks.
Choose material of tank
So with the technical requirements of the topic, the material selected for the tank ensures the following factors:
• Capable of withstanding high cavitation
• The machine frame is easy to clean, ensuring aesthetics
• Easy to disassemble and maintain
Therefore, Inox will be choice by team
Table 3.4 Advantages and disadvantages of material for tank
Inox 304 • Corrosion resistance: Stainless steel 304 has high corrosion resistance to water, air, organic compounds and many common chemicals
• High strength, making it resistant to strong impacts
• Easily cut, weld, shape and machine complex shapes This reduces production time and costs
• Especially very safe when in contact with food
The material can absorb small quantities of substances like magnesium (Mg) and sulfide (S), which leads to the formation of black dots on its surface This surface discoloration can negatively impact the appearance and aesthetic appeal of the material.
Inox 201 • This type of stainless steel is also non-magnetic, durable with time
• The price of the product is not too high
• Not suitable for salt environments: Type 304 is not recommended for use in environments with high salt concentrations, such as by the sea, as it is susceptible to salt corrosion
• There should be a separate preservation method for each different type of steel plate
Inox403 • Low cost • This stainless steel is susceptible to magnetic contamination
• Easily affected by the surrounding environment, making the product tarnished, no longer shiny
Conclusion: Based on the characteristics of each type of stainless steel, the team decided to choose 304 stainless steel as the most suitable type.
Sketch machine structure
Figure 3.7 Design machine structure on solidworks
DESIGN OF MECHANICAL SYSTEM
Introduction
The selection of the mechanism and transmission plan outlined in Chapter 3 provides the foundation for calculating, comparing, and choosing appropriate machine parts and components This process ensures that the final design meets the group's technical requirements, optimizing performance and reliability.
This chapter provides comprehensive calculation methods, detailed design formulas, and guidance for selecting essential equipment to build a complete mechanical machine system The team has successfully completed the mechanical design, ensuring all components meet initial specifications through precise calculations and careful part selection The mechanical setup guarantees smooth, continuous, and vibration-free operation, minimizing delays to achieve highly accurate measurement results, thereby ensuring the system's reliability and efficiency.
Machine structure requirements
• The machine operates reciprocally along the X axis according to the selected mechanism “Screw Drive” Movement range from 50 mm to 1000 mm
• The machine operates reciprocally along the X axis according to the selected mechanism “Pneumatic” Movement range from 0 mm to 200 mm
• Always ensure safety when operating the machine
Calculation and selection of components
A Choose type of ball screw:
There are two types of lead screws: normal lead screws and ball screws
Normal lead screws Ball screws
• High transmission precision, large gear ratio
• Smooth transmission, capable of self- braking, large transmission force
• Fast drive is possible with lead screw with large pitch or number of revolutions
• The transmission efficiency is low, so it is rarely used to perform the main movements
• Low friction loss should have high efficiency, can reach 90-95%
• Friction force is almost independent of motion speed, so it ensures movement at small speeds
• There is almost no gap in the joint and can generate initial tension, ensuring high axial rigidity
• Because of these advantages, ball nut ball screws are often used for machines that require precise linear transmission such as drilling machines, coordinate boring machines, numerical program control machines
Figure 4.3 The relationship between friction and speed of two types of roller screws
Based on its superior working ability and efficiency, the team selected the ball screw as the optimal choice The ball screw features minimal and stable friction that remains consistent regardless of speed, enhancing its performance Observations from the performance diagram demonstrate that the ball screw requires significantly less startup time compared to a standard lead screw Consequently, the ball screw proves to be the most suitable and efficient option for the application.
Table 4.2 Advantages and disadvantages of Motion
C The drive mechanism integrates the roller screw and the rail:
Linear Motion • Because the linear guide is influenced by the rolling friction of the bearing, it is easier to slip
• High hardness, good load bearing
• Long life, rarely abraded, good anti-vibration
• Easy to maintain and repair
Steel Ball Rail • High-precision circular sliders and sliders
• Easy to maintain and repair
• Low hardness, not good load bearing
Figure 4.4 Structure of LM Guide Actuator Model KR
• Available on the market in a variety of sizes (Reducing design and installation time)
• Can be used in any installation direction
• Reduced load fluctuations allow high-precision operation
Conclusion of selection of drive and guide:
To optimize space and efficiency in machine design while maintaining rigidity and smooth operation, the team selected a transmission mechanism featuring integrated vitme and sliding rail They utilized THK's slide rail lead screw, Model Kr, for all three axes—X, Y, and Z Given that the Y axis must support a heavier load, two square rail sliders were added to enhance its structural rigidity and ensure stable, precise movement.
The design process focuses on the concept of the simplest machine, emphasizing that all components should be easy to repair and manipulate This approach ensures the system's robustness and rigidity, particularly for the components located on the X-axis, resulting in a durable and maintainable machine.
The pedestal designed for the rail to slide and support the lead screw must be highly durable and stable, ensuring reliable operation Its top surface should be precisely machined to achieve smoothness and flatness, facilitating the accurate installation of two sieves and the lead screws This robust pedestal is essential for maintaining the overall stability and precision of the system, making it a critical component in the mechanical assembly.
LM Guide + Ball Screw = Integral-structure Actuator
LM Guide Actuator Model KR
Load m=3 kg (minus factor of safety k = 1.5)
Maximum acceleration of the system a = g/2 = 5 m/𝑠 2
No-load position accuracy ± 0,03/1000mm
- Maximum axial force when turning to the right:
- Maximum axial force when going left:
F 1max ; F 2max : Maximum axial force when machined and unmachined
Maximum rotation speeds, represented as N 1max and N 2max, remain consistent whether the machine is actively machining or idle, since the machine's weight stays nearly constant in both states Additionally, t 1 and t 2 denote the durations the machine spends in idle and load modes, respectively Understanding these parameters is crucial for optimizing machine performance and ensuring safety during operation.
Axial force of X Velocity (rpm) Time (%)
• Calculation of static load: a max o o s a max s
- f s : Static safety factor (for industrial production machines: 1.2 ÷ 2; for machine tools: 1.5 ÷ 3), inferred to choose fs = 2
- F amax : Maximum axial force (Famax = 58 (N)
- Load factor: f w are checked based on the following table:
- Choose the type of fixed-support bearing so f = 15.2
- Choose a motor rotation speed of about 80% of the critical motor speed, so: n = 0.8.75 = 60 (rpm)
- The radius of the screw shaft is calculated by the formula:
With lead screw diameter = 10 mm choose bearing T1 Kp000
Based on the available input parameters to calculate the necessary parameters of the motor to satisfy the initial requirements
Choose roller screw with step h = 10mm
Coefficient of sliding friction between steel and cast iron
The mass of the displacement head part m = 3 kg
Maximum rotational speed of the motor 2000 vg/ph
To choose the right engine, first of all, it is necessary to compare the advantages and disadvantages of different types of engines
Table 4.8 Type of Servo Motor
Stepper Motor DC Servo Motor AC Servo Motor
Control method Used in open loop controller
Used in closed loop controller
Used in closed loop controller
No feedback signal, error prone
There is feedback about, less error
There is feedback about, less error
No need Encoder Need Encoder and
Need Encoder and Gearbox to control accuracy
Moment At low speed there is large torque At high speed there is small torque
There is a huge moment Beneficial when driving at high torque
Size Motor Small Size Big size Bigger than stepper motor but smaller than
DC Servo in the same power
Causes more noise and vibration
Noise Very Noise Fewer noise Limit noise
Price Less expensive than servo motor
• Conclusion: After making a table to compare motor types with each other, we decide to choose Step motor Because There are compact motor, low travel speed, medium torque, low cost
Calculate the moment of friction:
2.𝜋.1.0,9 = 1,1(𝑁𝑚) (22) Since the structure is horizontal, α=0 or Mwz=0
Conclusion: From the static torque and screw radius, we choose the size 57 stepper motor
Figure 4.6 Step Motor Size 57 Table 4.9 Techincal specifications of stepper motor
To be able to completely immerse the object in the washing tank, with the weight of the basket about 300g, we can choose the type of cylinder AIRTAC TN16
Figure 4.8 Specification of Cylinder AIRTAC TN16-125
Manufacture Parts
Table 4.10 List of manufacture Parts
1 Pressing, cut laser, manufact ure hole
1 Cut laser, manufa cture hole
1 Pressin g,cut laser, manufa cture hole
1 Pressin g,cut laser, manufa cture hole
After selection and calculation We proceed to process the parts and assemble Finally we have the complete model:
DESIGN OF ELECTRICAL AND CONTROL SYSTEM
System block diagram
Functions of each main block:
Figure 5.1 Block diagram of the entire system
A 1-phase 220V AC source is converted to 24VDC and 12VDC through an AC/DC converter, providing reliable power for various electronic devices The 24VDC output is ideal for powering cooling fans, step drivers, and solid-state relays (SSRs), ensuring smooth operation Meanwhile, the 12VDC output supports devices like relays, water level sensors, pumps, and temperature sensors, enabling efficient and safe device functionality This setup is essential for applications requiring stable low-voltage DC power supply in automation and industrial systems.
The STM32F103C8T6 microcontroller serves as the central processing unit, handling input signals from sensors like temperature sensors, receiving control commands from the C# interface, processing this data efficiently, and displaying the relevant information on the user interface This microcontroller meets all essential performance parameters, ensuring reliable and accurate operation of the system.
The Display and Control Block is built with a user-friendly C# WinForm interface that serves as the core control system It enables users to effortlessly manage key functions such as setting temperatures, adjusting PID controller parameters, and configuring ultrasonic cleaning durations Designed for clarity, simplicity, and effectiveness, this interface ensures users can easily monitor system performance and view real-time results displayed on the visual screen.
The Execution Mechanism Block is responsible for operating the machine based on instructions from the central processing unit It comprises critical components such as the X-axis drive transmission system and the material supply system, ensuring precise movement and material handling This subsystem plays a vital role in executing commands efficiently, maintaining seamless machine functionality and optimizing overall productivity.
• Signal Acquisition Block: Specifically, temperature sensors and water level sensors Its main task is to measure data and send the parameters to the central processing unit as required.
Calculation and Selection of Components
5.2.1 Pump Motor and Water Level Sensor Selection:
To optimize the washing tank system, which measures 25x25x15 mm with a 10-liter capacity, a compact pump motor is essential A small-sized submersible pump powered by 5V, capable of delivering a flow rate of 1.2-1.6 liters per minute, is ideal for ensuring efficient water circulation relative to the tank volume The water pipe, with a 15mm diameter, complements this setup by facilitating effective water transfer within the system.
Table 5.1 Specifications of the 5V mini pump
Figure 5.3 Picture of 5V mini pump
The water level sensor monitors the water level in the tank, providing clear visual indicators of its status When the water level falls below the required threshold before pumping, the sensor displays a red light on the interface to signal low water Conversely, once the tank is filled to the desired level, the sensor shows a green light, confirming sufficient water supply This reliable monitoring ensures efficient water management and prevents overflow or dry running of pumps.
Table 5.2 Specifications of the water level sensor
Figure 5.4 Picture of the water level sensor
A Overview of the Temperature Control Unit:
The temperature control unit is essential in numerous industrial applications, including drying ovens, egg incubators, baking ovens, steam boilers, humidity control systems, and compressed air systems It offers versatile control modes such as on-off control, linear control, PID control, and ON-OFF control to meet various process requirements These units ensure precise temperature regulation, enhancing the efficiency and safety of industrial operations.
In addition, with PID control mode, the temperature control unit adjusts the system temperature to match the set temperature as quickly and accurately as possible
The control unit efficiently manages parameters like humidity, pressure, and flow rate through input signals such as 4-20mA, 0-10 VDC, and 0-5 VDC It features advanced functions including temperature alarms, direct value setting via a user-friendly display, self-adjustment capabilities, and adaptive mode for optimal performance These capabilities make it a versatile solution for precise environmental regulation.
Figure 5.6 Closed-loop PID control diagram
For temperature control applications, the system utilizes two input signals: the desired set temperature and the actual temperature feedback, with the control output signal adjusting the triac's angle for precise regulation Due to the challenges in modeling the entire system, an identification method is employed to accurately determine the transfer function, which is characterized as a first-order lag element This transfer function serves as the basis for designing effective PID control parameters, ensuring stable and efficient temperature regulation.
PID (Proportional-Integral-Derivative) is a widely used feedback control mechanism that enhances system stability and accuracy Comprising three key components—proportional, integral, and derivative—PID controllers are essential in industrial automation, electrical systems, and electronics Due to their effectiveness in regulating processes, PID controllers are considered the most common and reliable choice in control system applications.
PID control is a complex process used to achieve a desired setpoint value, such as temperature, pressure, or flow rate
There are four types of control:
Proportional and Integral (PI) Controller
Proportional and Derivative (PD) Controller
Proportional, Integral, and Derivative (PID) Controller
PID controllers are regarded as the ideal solution for modern control systems due to their widespread use in automated process control across various industries They effectively minimize steady-state error, reduce system oscillations, and enhance overall performance by improving settling time and limiting overshoot.
Figure 5.7 Response Graph when using the components of a PID controller
This temperature control circuit utilizes a PID controller to precisely manage a 220V/500W heating resistor It regulates the on/off switching of a TRIAC, adjusting the voltage supplied to the heating element By modulating the power delivered to the resistor, the system maintains the desired temperature with high accuracy and stability.
The circuit is designed to detect the zero-crossing point of the AC voltage, ensuring precise synchronization for controlling power delivery It implements a PID controller to accurately regulate the heating process By adjusting the firing angle at the TRIAC gate, the circuit effectively controls the temperature of the heating resistor, providing efficient and stable thermal management.
The K-type thermocouple is the most widely used thermocouple across various industries due to its reliable performance in temperature measurement A thermocouple is a thermal sensing device made of two different metal wires joined at both ends, forming a closed circuit When there is a temperature difference between the two junctions, it generates an electric current that can be measured to determine the temperature accurately.
There are various types of thermocouples, each represented by a letter (K, J, E, T,
K Type Thermocouple has main ingredient is Nickel, which is commonly used in industry with temperature measurement applications due to the following advantages:
Table 5.3 Advantages and disadvantages of K Type Thermalcouple
The ability to measure extremely high temperatures for a long time
The error is about 1% over the full range
Can measure high temperature continuously
Able to with stand temperature rise/fall suddenly
Its output is in the form of mV (millivolts) This signal is very small, so it is easy to noise when transmitting over long distances
Reasonable price When used, there will be a certain delay
Table 5.4 Specifications of the temperature sensor
Temperature Sensor Type: Thermocouple K Type
Wire: Metal coated sensor wire
The MAX6675 enhances the signals from K-type thermocouples, providing high-accuracy and stable temperature measurements in industrial environments Utilizing SPI communication, it reliably transfers sensor data to the microcontroller Its application in industrial temperature measurement systems ensures precise readings and durable, long-lasting performance.
Table 5.5 Specifications of the MAX6675 Converter
Resolution: ADC 12bit, 0.25 degree K/unit
• How to use MAX6675 and K-type Thermalcouple:
Measuring the small voltage output from a K-type thermocouple can be challenging; therefore, I utilize the MAX6675 ADC converter circuit, which simplifies signal processing The MAX6675 communicates with the microprocessor via the SPI interface, enabling accurate and efficient temperature data acquisition.
Figure 5.11 Connect between MAX6675 and Microcontroller
When the CS pin is pulled low, the SCK clock pin goes high, triggering the SO pin to transfer and shift data from bit 15 to bit 0 Once the CS pin returns to high, the transmission line is interrupted, ending the data read cycle Each data transfer comprises 16 bits, where bits 15 and 0-2 contain device-specific information and are unused The remaining 12 bits, specifically bits 3 to 14, carry the temperature data to be read.
According to the manufacturer's datasheet, a sensor reading with all bits set to 0 corresponds to 0°C, while all bits set to 1 represent 1024°C With a 12-bit data length, the maximum value is 2^12 = 4096, meaning the raw temperature data must be divided by 4 to obtain the actual temperature in Celsius This calibration ensures accurate temperature measurement and effective sensor performance.
- Configure PIN STM32 on MXCube
Figure 5.13 Configure Pin STM32 on MXCube
- Coding base on datasheet of MAX6675 and simulation on Proteus
Figure 5.15 Read value from Oscilliscope
The 220V sinusoidal voltage operates at a frequency of 50Hz with a period (T) of 0.02 seconds During each cycle, the voltage transitions from negative to positive or vice versa every half cycle, which lasts approximately 10 milliseconds (10ms or 10,000 microseconds), resulting in moments when the voltage is zero To control power effectively, the circuit adjusts by briefly stopping the voltage supply during these intervals in the previous half-cycle when delivering control pulses to the triac, enabling precise regulation of power.
Voltage and current of components
Table 5.14 Voltage and current of components
No Name of Component Voltage Current
3 Driver TB6560 10-35 VDC No mention
4 Water Level Sensor 3~5VDC < 20mA
7 TRIAC TB134 220VAC No mention
8 Heat Water Risistor 220VAC No mention
10 Worm Resistor 220VDC No mention
The object should need 4 power sources for the system to operate: One is, 220 VAC
AC to control 220VAC loads The second is a 24VDC DC power supply the second is a
12 DC power supply And the last is 5VDC
Figure 5.45 Power Supply 24V 5A Table 5.15 Technical Specifications of Power Supply 24V 5A
Table 5.16 Technical Specifications of Power Supply 24V 5A
Table 5.17 Technical Specifications of LM2596S
Construction of electrical cabinets
5.4.1 Design printed circuit on Altium:
Figure 5.50 Layout of board circuit
Monitoring and Control Interface
We have developed a C#-based application to enable convenient monitoring and management of the system This user-friendly interface simplifies overseeing system operations and ensures efficient control (Include relevant keywords such as "system management," "monitoring application," and "C# interface" for SEO optimization.)
The application consists of three main parts:
• Parameter setup and basic control section
Connection section: This part of the application establishes a connection between the user’s computer and the sandpaper washing machine through UART communication
To establish the connection, the user needs to enter the correct COM port and Baudrate, and then press the “Connect” button
5.5.2 Parameter setup and basic control section:
This section includes settings for temperature, Kp, Ki, Kd, set timer, Jog +, Jog-, and water pump
Temperature setting and PID parameters: used to control the water temperature in the washing tank so that it responds as quickly and stably as possible
Set timer: sets the desired time for the sandpaper washing system
Jog +, Jog - : used to control the working arm to the desired position When in normal running mode, the machine will control it automatically
When you press the water pump button, water is pumped into the washing tank The system automatically stops the water pump once the water reaches an adequate level for sandpaper washing This ensures efficient operation and prevents overflow, providing a seamless washing process.
Run: when the temperature and water level are sufficient for sandpaper washing, the user presses the "Run" button to start the washing process
Water level monitoring is essential for ensuring optimal washing performance When the washing tank is empty, the interface displays the water level in red, indicating the need to add water Once the tank is filled to a sufficient level for the washing process, the interface updates to display the water level in green, confirming adequate water supply Accurate water level monitoring helps maintain efficient operation and prevents potential damage due to dry running.
Temperature monitoring: It shows the temperature in numerical form and also through a chart to allow users to easily track the temperature.