Machine design, tập 84, số 01, 2012

Korane An inside look at planetary gears by General Dynamics Land Systems, Sterling Heights, Mich., on several military vehicles, including the Expeditionary Fighting Vehicle, the Futur

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Supplying reliable quality components for the automation and control industries

page 58 HOW TO WORK WITH PLANETARY GEARS , page 62

Box-beam tracks

make rides

thrilling

page 20

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gearing provides fast positioning and smooth movement, and sealed boxes keep out abrasive dust generated during cutting.

gear-r-JNJUOPJTFBOEWJCSBUJPOBOENFFUTUSJDUCBDLMBTISFRVJSFNFOUTJOTDBOOJOH

tables for cardiovascular patients.

speeds up to four slices/sec Also available are slim, right-angle designs to

Planetary gearheads can improve machine performance and efficiency, and lower costs But proper sizing

is critical.

Authored by:

Howard Horn

Product Manager Thomson Industries, Inc.

Wood Dale, Ill.

Edited by Kenneth J Korane

An inside look at

planetary gears

by General Dynamics Land Systems, Sterling Heights, Mich., on several military vehicles, including the Expeditionary Fighting Vehicle, the Future Combat System for the Army, and the Joint Light Tactical Vehicle for the Army, Fredserts also went into several thousand Humvees when they were upgraded.

Here are several female Fredserts installed in the sidewall of a military vehicle

The four oval the head of the Fredsert mate with drive lugs on the tool used to install Fredserts.

removed for any reason, it must be drilled out This risks

be clumsy and difficult if the insert is not easily accessible.

Another limitation is that inserts typically cannot ate air and watertight seals without using a thread-locking

cre-so there is still a leak path.

And finally, there’s a limited range of standard threaded inserts on the market, and custom lengths or materials are

Engineers at General Dynamics Land Systems, Sterling

Corps The amphibious combat craft needed to be made

soft, and fasteners used to attach components to the

in place solidly, resist extreme vibrations and shock, and

in the field.

In search of an insert

The design team wanted to use threaded inserts, a mon practice when putting bolts in soft metals like aluminum and magnesium Inserts, usually made of a tough give a strong, wear-resistant interface to install bolts into.

com-Although engineers have a few basic types of threaded inserts to choose from, including key-locking, ring-locking, and helical-spring, none met the U S Marine Corps

Fredserts give engineers a put bolts in soft metal.

A threaded insert

TOUGH ENOUGH

for the Marines

Authored by:

Jason Deters

Senior Engineer Process & Technology Development

General Dynamics Land Systems

Sterling Heights, Mich

Edited by Stephen J Mraz

Vehicle, and Fredserts have been used on several other

Mk 46 naval-gun turret, the Army’s Future Combat tem and Joint Light Tactical Vehicles, the Navy’s Littoral more than 12,000 upgraded Humvees made by AM Gen-

Sys-eral, South Bend, Ind.

Fredserts’ advantages

A Fredsert combines a tapered thread profile, 100% thread engagement, cutting flutes, and a flanged head to compared to other inserts and tapered in certain areas so that they create a friction-fit when installed into the parent material (such as aluminum) And all of the Fredsert’s use standard bolt threads that end up with significantly area.

The flanged head also helps in that it gets torqued down onto the parent material and contributes to the locking ac- tion Fredserts are designed to exceed the tensile strength

This lack of flexibility often means engineers must alter their designs to accommodate available insert sizes or material options.

Faced with requirements it could not meet with mercially available threaded inserts, General Dynamics and now-retired tool engineer named Fred Wheeler, the team came up with the Fredsert after 12 months of development, testing, and redesign Ultimately, more than 6,000

com-JANUARY 19, 2012

MACHINE Design.com

Access our Reader Service Web site to quickly find and request information on the products and services found

High forces and extreme speeds made

possible by stronger and smoother

box-shaped rails

A “million-dollar” idea?

How inventors can move from hopes and

dreams to reality and the marketplace

A threaded insert tough

enough for the Marines

Fredserts give engineers a new way

to put bolts in soft metal

Giving

Power-over-Ethernet some muscle

As power-over-Ethernet applications

expand, demands for even more

power are following right along

An inside look at

planetary gears

Planetary gearheads can improve

machine performance and efficiency and

lower costs But proper sizing is critical

JANUARY 19, 2012

MACHINE DESIGN.com

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For customized article reprints and permissions please contact: Penton Reprints, 1-888-858-8851, e-mail at reprints@pentonreprints.com or visit

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EDITORIAL

How to ace an engineering job interview

EDITORIAL STAFF

LETTERS

SCANNING FOR IDEAS

Efficiency lets smaller motors handle bigger jobs

Overpressure valve protects lithium-ion battery packs

Agile product development and strong-form product

management — Barry Jaruzelski, Richard Holman

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In that regard, it looks as though the new trend in job interviews is to ask brain-teaser-type questions The practice seems to have been popularized by hiring managers at Google According to William Poundstone, author of a

book called, Are you smart enough to work at Google?, that company relies on

such off-beat interview questions as a way of sifting out people who won’t fit into its culture

You might wonder what kind of culture a company has if it hires people based on how they answer a question like, “You are shrunk to the height of a nickel and thrown into a blender Your mass is reduced so that your density

is the same as usual The blades start moving in 60 seconds What do you do?”

Apparently Googlites are looking for inventive answers (One of the best

is supposedly to recognize that small creatures are stronger in proportion

to their weight and that you can probably just jump out of the blender.) other company that apparently buys into brain-teaser interview questions

An-is Tesla Motors Tesla interviewees reporting on the Glassdoor.com site say

the EV maker mixes brain-teasers with queries about fundamental physics, including: Why do letters in mirrors reverse horizontally and not vertically? You’re in a row boat, which is in a large tank filled with water You have an anchor on board and throw it overboard (The chain is long enough so the anchor rests completely on the bottom of the tank) Does the water level in the tank rise or fall?

Though riddlelike interview questions get a lot of attention, the more portant part of a hiring process is probably the questions applicants answer that resemble the work they’ll eventually perform People applying for pro-gramming positions at Google, for example, must write code during their interviews But at any engineering company, sometimes even work-related questions can seem a bit off the wall

im-A friend of mine describes an incident during one such interview at a control-systems engineering firm: “I extolled my past experience and cre-dentials, but I could tell the guy doing the interview wasn’t convinced All of

a sudden he eyes me suspiciously and says, ‘What’s the integral of 1 over x?’

To my extreme surprise I seemed to recall it was log(x), and though unsure

I blurted out my answer He brightened measurably and said, ‘That’s the question I use to separate out the real engineers!’ I got the job, even though I could not have worked a control-theory integral problem to save my soul.”The fallacy with questions that demand mental gymnastics is that they don’t say much about how the applicant will perform day-to-day work

“What you see is not always what you get,” says Dean Stamoulis, head of the Global Executive Assessment Practice for Russell Reynolds Associates in New York City He also notes that some of the best candidates don’t make good first impressions, and it’s important to look deeper than an initial per-ception Finally, he advises that sometimes what is not said in an interview

is important as well “If an interviewee doesn’t mention others he or she led and name key contributors to past successes, that might indicate he or she is taking credit for others’ work and ideas.”

— Leland Teschler, Editor

RS# 107

JANUARY 19, 2012

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NEWS FEATURES Stephen J Mraz,

stephen.mraz@penton.com

CAD/CAM Leslie Gordon,

leslie.gordon@penton.com

ELECTRICAL, ELECTRONICS Robert J Repas, Jr.,

robert.repas@penton.com

FASTENING, JOINING Jessica Shapiro,

jessica.shapiro@penton.com

FLUID POWER Kenneth J Korane,

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MANUFACTURING Leslie Gordon,

leslie.gordon@penton.com

Kenneth J Korane,

MATERIALS Jessica Shapiro,

MECHANICAL Kenneth J Korane,

Jessica Shapiro,

EDITORIAL PRODUCTION Denise Greco,

Editorial Production Manager

Randall L Rubenking, Art Director

RS# 110 RS# 109

JANUARY 19, 2012

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RS# 111

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Who stole our innovation?

Thanks for your editorial on the

h u rd l e s to i n n ov a t i o n ( “ R & D Doesn’t Mean Innovation,” Oct 6) I agree with you that patent trolls hin-der innovation, but the cause is not the patent system, nor is the solution

to eliminate it

The patent system is necessary

to sustain long-term R&D efforts If a company spends millions of dollars developing and marketing a prod-uct, they need time to recoup their investment to stay in business as well

as fund future R&D projects

As I see it, patent trolls are the real cause of our stifled innovation, and

we should work to eliminate them

One way to get rid of them might be

to require that patent holders use the technology in their patent ap-plications in real products that are released to the market The patent-pending technology should not only

be used for production, but also have sales volumes that let manufacturers

at least break even, say at the end of the third year Under such require-ments, approval of the patent appli-cation would be tied to the benefits the patent offers to the economy

This solution should stop patent trolling and leave the real work to those serious about bringing in-novations to society

Eugene Kim

In the late 80s, I worked at a tool house which won a contract to build a family of dies that were to

be used to fabricate heat ers for home gas furnaces I traveled

exchang-to the plant where the exchang-tools would

Nontraining

Your recent editorial (“Training that

Doesn’t Train Anyone,” Nov 3) struck

a spark I work with young people by

taking promising ones into my shop

for a few weeks to train them on a

variety of shop practices, including

gear cutting, lathe and mill

opera-tion, grinding, metallurgy, heat

treat-ing, weldtreat-ing, CAD, and inspection

My shop is more complete than any

college shop I’ve seen The end result

is that after three weeks, the student

usually lands a job at $17/hr with full

benefits

One recent “graduate” phoned

and told me that after two weeks

he’s now manager/foreman over the

grinding department in his company

He was a high-school graduate with

fairly good grades and had

gradu-ated from a diesel-mechanics school,

and couldn’t find a job

It seems I know the skills that

companies need but can’t find or

won’t train people for Humility

pre-vents me from saying I must be a

genius compared to the people the

government has working for them

as “educators.” Oh, and I do it for

nothing

Steve Tuttle

At the beginning of your

edito-rial, you mention CAD software

vendors offering training on their

software to anyone who has fallen

victim to an economy that the

amazing prodigies in our

govern-ment are so dedicated to

improv-ing I hope those vendors are also

training those people on what

makes a good mechanical drawing

or 3D part model I once worked

at a company that evidently hired

designers and drafters based on

the simple fact that they had once

double-clicked an AutoCAD icon

Most of them were fired or quit

without notice after a brief time

Learning a piece of software and

learning a trade may go hand in

hand, but one does not equal the

other For example, I am

knowl-edgeable about spreadsheets, but

that doesn’t mean you want me

doing your bookkeeping

Joel W Suffridge

be used to go over requirements While there, I was given a plant tour, including the “Research Lab.” I was shocked to find that all of the research consisted of dismantling competitors’ furnaces to see if there were any ideas worth stealing My boss and I had a good laugh about this company’s research

Fast forward to late 90s with other company and now I was in-volved with dies to fabricate com-ponents for home air conditioners Again a plant tour included the re-search lab This company’s research consisted of studying competitors A/C units looking for ways to improve their own products

an-I must conclude that either the two companies I visited were the only two dishonest HVAC firms or the whole industry does nothing more than pirate from competition There must be a HVAC innovator out there somewhere, but I sure did not see the evidence

Ralph L Wirtel

When will we realize as a society that throwing money at a problem doesn’t ensure success? We need not look any further than public educa-tion to see that Many school districts that spend the most per student are among the lowest performers.More to your point, what I’ve seen over the past 20 years is a steadily growing myopia among decision makers both in industry and govern-ment when it comes to innovation and R&D About two-thirds of my career has been in military-funded R&D and the other third in commer-

JANUARY 19, 2012

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RS# 112

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of the patent system Yet, your point

is well taken; the system gets abused

by people with little or no moral viction other than making as much money as they can while expending

con-as little real effort con-as possible One counter to the patent trolls is the use

of trade secrets This is especially fective with processes used to make generic products when the result cannot be differentiated in the final product Yet, they can be effective

ef-in differentiable products Consider Coca-Cola and Heinz ketchup; nei-ther has patented their formulations (which would’ve run out decades ago) but, they have viable businesses based on trade secrets

Christopher Perhala

One of the main points Dr Michael

Hammer made in his 1993 book,

Re-engineering the Corporation, still rings

true today; hierarchical structures get in the way of change Hierarchi-cal structures inherently have a lot of activities going on that do not add value to the company’s products or services The primary objective of a bureaucracy is self-preservation, the second is growth

I’ve come to the conclusion that there is not much an individual or even a group of individuals at the working level can do aside from mov-ing to a smaller company or starting one of their own,

Yet, many technological advances require a substantial investment in in-frastructure that individuals or small companies do not command For ex-ample, if someone comes up with a new way to make steel that uses 20%

less energy, where does she or he go

if the company they work for isn’t terested because the investment it

in-cial product development The

Com-mercial-Off-The-Shelf revolution in

government acquisition has much

to do with shorter term thinking — it

emphasizes evolutionary

(develop-ment) advances over revolutionary

(research) ones Most government

program managers would prefer to

modify a commercial device or

sys-tem to military purposes rather than

come up with a truly new idea and

product COTS reduces development

time, cost, and, most importantly

these days, risk

Yet, the commercial sector doesn’t

seem to fare better Managers seem

to have mastered the art of putting

the “no” in innovation There are so

many layers and gatekeepers in large

organizations that out-of-the-box

ideas are easily smothered Those

that aren’t smothered often get

de-layed for such a long time that by the

time they garner support, the need

for them or the market opportunity

has long since passed

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HUCK BOBTAIL

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RS# 115

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SCANNING FOR IDEAS

Edited by Stephen J Mraz

Platinum e Motors from Leeson Electric Corp., Grafton, Wis (www.leeson.

com), use a range of advanced features that increase their efficiency and

power density, letting customers get more power out of smaller motors

The permanent-magnet ac motors are also built to CI Severe Duty

standards, making them suitable for use in harsh environments

Platinum e motors use a different type of rotor than most

other induction motors In squirrel-cage motors, current is

Request free in formation via o

ur Reader Service Web site at

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Efficiency lets smaller motors

handle bigger jobs

induced into the rotor from the

field (stator) through an air gap,

and conducted through a

bar of aluminum or other

conductive

mate-rial These bars are

most often die cast

and mounted in

the rotor

lamina-tions’ slots In

Plati-num e motors, the

rotor itself contains

permanent-magnet

material, which is

surface mounted to

the rotor lamination stack or

embedded within the

lamina-tions In both cases, electrical

power is supplied through the

stator windings

The motors use concentrated

windings, essentially a bobbin

winding Therefore, unlike

distrib-uted windings used in induction

motors, there are no shared slots

This eliminates the potential for

phase-to-phase shorts The

concen-trated windings also mean shorter

tion; cushioned and sleeved connections from the leads all the way into the turns;

and deep-penetrating, nonhygroscopic, high-temperature varnish, along with

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Motors are available with the common ac-induction-motor speeds of 3,600, 1,800,

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feed-back in open-loop operation or 2,000:1 in close-loop operation (with encoder)

RS# 401

end turns This reduces waste and makes room in the

housing for more active material, contributing to higher

power density (end turns do nothing to generate torque)

The motors carry the company’s inverter-rated insulation

system (IRIS), which protects against voltage spikes induced by

variable-frequency drives It includes specially formed phase

insula- magnet motor

Permanent-Conduit box includes a terminal block

Bearing for

180 frames and larger can

be greased

IP55 protection against the elements

IRIS insulation

Fractional motors feature rolled-steel construction Integral motors use cast-iron construction.

JANUARY 19, 2012

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RS# 116

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Overpressure valve protects

lithium-ion battery packs

Lithium-ion battery packs, which are

becoming more common in electric

vehicles, energy-storage, network

back-up devices, and other industrial

applications, can become

overpres-sured if gas accumulates inside This

can be dangerous and risks

damag-ing equipment To prevent such

overpressurizations, engineers at

Freudenberg Sealing Technologies

in Wienheim, Germany, developed a

simple pressure-control valve which

is now offered at Freudenberg-NOK

Sealing Technologies, Plymouth,

Mich (www.freudenberg-nok.com).

The lightweight valve uses an

engineered EPDM seal, which opens

when pressure inside the battery

pack exceeds a specific limit, but

there is no loose hardware during

such releases because the valve is

permanently tethered to the battery

pack The valve must be manually

replaced to reseal the battery pack

The valve can also be manually

opened, which can be handy when

shipping battery packs by air

Oth-erwise, pressure changes during

ascents and descents could damage

the battery housing And if a battery

fails and causes overpressurization,

the valve can be reset to protect

in-terior components during transport

to a recycling center

The overpressure valve is not

ad-justable Its fixed pressure release/

open point is designed into the

ge-ometry of the valve However, valves

can be developed to meet

customer-specific requirements

The EPDM seal resists leaking and

swelling and withstands

tempera-tures from –40 to 80°C Users can

add components which will add

pro-tection against impacts from stones

and other road debris or let it survive

industrial cleanings

RS# 402

Overpressure valve swings open to relieve pressure

Fixing element

Flexible EPDM serves as a hinge

JANUARY 19, 2012

18

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RS# 117

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REPORTER’S NOTEBOOK

In overhauling the rickety wooden

Texas Giant roller coaster in Six

Flags Over Texas amusement

park, Arlington, Tex., Six Flags

Chief Engineer Larry Chickola

wanted to design a coaster that

had exceedingly tall crests and

sharp turns, and make riders hold

on for their very lives The high

forces and extreme speeds he

envisioned necessitated stronger

and smoother rails than traditional

wood or tubular metal tracks He

turned to roller-coaster

manufac-turer Rocky Mountain

Construc-tion in Hayden, Idaho, which had

just designed an entirely new kind

of steel track The ride’s scaffolding

would still be wood to retain the

coaster’s old-time look, but the

new rails would safely support the

loads and accelerations necessary

to provide the most thrilling ride

possible

“The rail technology is different

from previous roller coasters in

that it is a box-beam, square metal

track,” says Rocky Mountain

Con-struction Design Engineer Alan

Schilke “An older track-fabrication

method — still in use today — is

to build up tracks by laminating

Box-shaped tracks let

mega-coasters soar

pieces of lumber together Trouble

is, today’s coasters hold such heavy loads and undergo such extreme forces that wooden track can no longer withstand the forces without frequent repair We have laid traditional wood track, but I thought there must be a better method.”

The result was the box-beam track, says Schilke “With this ap-proach, we cut large, flat sheets of

mild steel plate on large plasma cutters We weld the flat shapes longitudinally with typical wire-feed equipment to produce a three-dimensional rail.” Automated buggies carry welding equipment and lay down the welds The welds are cleaned and then inspected using magnetic particle testing for cracks, deviations, and pockets Finished 3D lengths run from 40 to 50-ft long

The new box-shaped rails safely support the loads and accelerations necessary to provide the most thrilling ride possible.

A plasma cutter is cutting a rail

component from a large sheet of

steel plate

JANUARY 19, 2012

20

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include bolts that stick up on the outside of the rails “However, the coaster wheels themselves only run on a smooth path In general, roller coasters stay on their tracks with the help of a three-wheel locking configuration consisting of side wheels, a top running wheel, and an uplift wheel.”

“Of the products we have stalled, there has been no main-tenance work needed on the box-beam tracks,” says Kilcup “In the future, we intend to help develop roller coasters where the cars run

tion’s method, bends in the track are cut directly in the flat metal

“Heat of welding causes the metal

to slightly change shape But the company’s patented technique restores the shape to the original engineering specs In the field, bolted-connection plates attach the lengths together

Says Kilcup, the design does

Traditional tubular steel

tracks are really just pipe that

has been measured, bent,

and shaped “Both the tubular

steel tracks and the new

box-beam rails can endure the

same amount of force, which

is much larger than wooden tracks

can handle,” adds Rocky Mountain

Technical Designer Jake Kilcup

“But the box-beam tracks arguably

provide the smoothest ride That’s

because we build the track to

en-gineered specs on high-tech CNC

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The multicopter could look like this by the time it comes on the market.

Rethinking the helicopter

E-volvo, a German firm, has totally redesigned the

helicopter Its multicopter boasts 16 electrically

pow-ered propellers divided into four groups of four Power

for up to 20 min of flight comes from a lithium battery

pack

The 175-lb manned prototype measures about

16 × 16 ft and can carry a payload equal to its own

weight Unlike conventional helicopters, the

multi-copter rotors are permanently

positioned They do not move

or change pitch, which should

greatly reduce wear compared

to conventional helicopter

rotors Instead, each set of

ro-tors has its own motor and the

amount of lift each rotor

gen-erates depends on how much

electricity it receives Several

onboard computers take pilot inputs from a throttle and joystick to calculate power signals for each of the

16 rotors that, in turn, change their speed to carry out the commands The computers also continually strive

to keep the copter upright This relieves the pilot of having to think about minimum speed, stalling, gas mixtures, pitch control, and the other issues that com-plicate helicopter flight

The aircraft also has a few safety features designed in For example, because there are

no overhead rotors, the copter can be outfitted with a parachute that could bring a failed multicopter safely to the ground Plus, the multicopter can safely land with up to four of

Resources:

E-volvo,

www.e-volo.com

The multicopter was checked out

during a series of flight tests The

white blocks on sticks hanging

down are landings gear that keep

the vehicle upright once it lands.

JANUARY 19, 2012

22

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Student projects weren’t like this in our day

Students at Brigham Young

University have had a good year

when it comes to electric vehicles

Two of the engineering school’s class projects recently set speed records, one at the Bonneville Salt Flats, the other on a drag strip at the Mason Dixon Dragway in Hag-erstown, Md

Electric Blue

After seven years of design, opment, and testing, BYU students saw their Electric Blue streamliner set a world’s land speed record for vehicles in the E-1 class, which covers electrically powered cars weighing less than 1,100 lb Power comes from 88 stripped-down bat-tery packs originally

devel-designed for DeWalt

cordless drills Each pack holds 10 lith-ium-ion batteries

A long, slender, carbon-fiber body encloses all four wheels, making the car light and aero-dynamic The rear wheels are solid aluminum, which lets them handle the high torque and speed, as well as ground condi-tions on the Utah salt flats

The car has a 600-ft turning radius

(An average car’s is

35 ft.) But steering

is not an issue when making speed runs at Bonneville

The car averaged 155.8 mph over two runs conducted on two consecutive days, a requirement for setting a land-speed record, On one run, it clocked

175 mph (In a shot at

the record last year, the BYU car hit

180 mph on the second day, but then hit a rut and rolled before it could complete that second run.)

EV 1

A different team of BYU dents converted a 1997 EV-1

stu-donated by General Motors into

a dragster powered by tors It set a new record for mod-ified-production/Class A electric vehicles, which is for production cars running on more than 240 V The BYU entry was the only one

ultracapaci-in its category, but the team lenged itself to best the record

chal-it set two years ago, which was

77 mph, or 15.9 sec in the quarter

Electric Blue, a streamlined vehicle designed and built by BYU students, set a land speed record on the Utah salt flats.

RS# 119

JANUARY 19, 2012

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pacitors from Maxwell

Technolo-gies, San Diego, which initially

presented problems Students designed the car to run on 400 V, but by the end of quarter-mile run, the capacitors would be down

to 275 V The team solved that problem by doubling the number

of capacitors The bank of tors is recharged between runs from the team’s specially outfitted truck, a process that takes 15 to

capaci-20 min Some of the benefits of ing capacitors instead of batteries include their quick cycle times and

mile The new record is 93 mph

and 14.08 sec, which the team set

on its third run The team went for

a fourth run, trying to top 100 mph

and 13.5 sec, but a sheared drive

sprocket ended that effort

One of the changes the team

made to the car since the last

record-setting run was to switch

from a transmission with only one

gear to a chain-driven two-speed

transmission The transmission, by

the way, is the only component on

the car that makes an appreciable

An electric vehicle named simply EV 1 became a capacitor-powered dragster, thanks

to a team of BYU students.

RS# 120 JANUARY 19, 2012

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When

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The Navy will be testing new

software and lighting that could help pilots accurately land on air-craft carrier decks despite rolling seas If successful, the technology should boost safety, reduce train-ing requirements, and cut main-tenance costs by lowering the number of hard landings

Currently, Navy and Marine

pilots constantly adjust speed and altitude to stay on the proper glide path to a touchdown on a carrier’s heaving deck A Fresnel light tied to a landing system lets

approaching pilots know if they are above or below the glide path

Lining up with the angled and moving landing deck takes place with the help of Landing Signal Officers on the rear of the ship ob-serving each approach

In the new system, what’s called a Bedford Array of lights embedded in the flight deck down the center of the landing area is controlled in part by the ship’s pitch and roll The brightest light an approaching pilot sees

at any time represents a visual

Software and new lighting knuckle carrier landings a

RS# 121

JANUARY 19, 2012

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GORE® Wire and Cable

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target stabilized with respect

to the proper glideslope for his

or her aircraft Meanwhile, the

pilot’s heads-up display shows a

dotted green line It represents

the plane’s future flight path

based on real-time inputs from

the cockpit’s control stick The

pilot maneuvers the dotted line,

along with his plane, to pass

over the stabilized target light

on the ship’s deck, and the

air-craft will do what is necessary to

ensure it touches down at the

could make

thing of the past

RS# 122

JANUARY 19, 2012

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The iwis chain cascade in Clean Mobile’s direct dual drive gives a 1:38 reduction ratio It operates across a wide speed range with about 80% efficiency.

A new chain drive promises to

improve the efficiency of electric

bikes and extend their range The

drive was jointly developed by

iwis Drive Systems and Clean

Mobile, a firm that makes electric

drives for two-wheeled vehicles

Both companies are based in

Mu-nich, Germany The hybrid unit

combines electric and human

power to reportedly deliver

ef-fortless acceleration and excellent

range both on and off-road

Clean Mobile’s designers

be-gan with a small, 1,200-W electric

motor that delivers 150 N-m of

torque Initial plans were to mount

the motor near the pedals and run

the motor at high speeds, even

at slow riding speeds It quickly

became clear this setup couldn’t

transmit power to the rear wheel

and meet efficiency targets with

conventional reduction gearing

The company approached

engi-neers at iwis, who recommended

splitting the gearing into a

pri-mary and secondary transmission

Primary gearing would handle

speed reduction at the pedal crank

and use standard components for

secondary power transmission to

the wheel

The result is the direct dual drive

(DDD), which uses three chains and sprockets to connect the pedal crank and adjacent motor shaft, to-gether yielding a 1:38 reduction ra-tio Engineers selected chains with the required strength and fatigue life based on forces on the teeth

of each sprocket and the ing overall transmission ratio The three-chain arrangement reduces motor speed from 3,600 rpm down

result-to pedaling speed A freewheel hub ensures that force exerted by the rider on the pedals goes only to the wheel, not the motor, should the battery ever fail A second idle

Chain drive boosts e-bike efficiency

RS# 123

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The DDD in Third Element’s

eSpire electric bike mounts

above the pedal crank and

behind the Li-ion battery pack.

Third Element’s eSpire

electric bicycle placed first

at last year’s E-bike world

championship.

man armed forces university

(Universität der Bundeswehr

München) in Neubiberg, near

Munich, showed an efficiency of approximately 80% across a broad operating range In contrast, typi-cal electric bikes have efficiencies ranging from 25 to 50%, according

to Clean Mobile officials

An eSpire bicycle equipped with DDD, built by Munich cy-

cleworks Third Element, won

the first official E-bike world championship at last year’s Inter-mot in Cologne, Germany — the world’s largest bicycle and mo-torcycle show Its electronic con-trols and torque sensors man-age energy flow from the Li-ion batteries to the wheel, further enhancing efficiency It has a top speed of 45 km/hr

iwis is developing erful units, as well as lower-rated versions that use plastic parts, to satisfy demand from builders of two, three, and four-wheel ve-

mechanism disengages the pedals from the rear wheel, as on conven-tional bicycles

The chains are major tors to the drive’s overall efficiency, explains Michael Frank, new business development project manager at iwis, because they only transmit tensile forces in the direction of travel A spur wheel with helical gearing, in contrast, would induce additional, lateral forces and thereby reduce overall efficiency, says Frank

contribu-Tests on the DDD by the partment of Drive, Control, and Actuator Technology at the Ger-

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LOOKING BACK

10 YEARS AGO — 2002

Segway’s secret: cleverly wound

servos: The Human Transporter

from inventor Dean Kamen gets its

power from special brushless servo

technology The Rockford, Ill.-based

Pacific Scientific Div of Danaher

Motion created a new sensor

de-sign for the Segway that allows feed-back to the motor-drive electronics with-out an encoder or resolver A patented

hemispherically wound stator features redundant windings which effectively realizes two functioning motors in one shell If one set of windings fails, the motor continues to operate An added benefit of this technology — a smaller motor Pacific Scientific also devised a proprietary process to injection mold key motor components and encapsu-late windings in one step The motor

is said to have 40% more torque than comparable motors

30 YEARS AGO — 1982

Sled to prove M-X missile system: A

rocket sled being developed will ject the guidance system of the M-X missile to

sub-the inertial loads it will encounter during launch and ascent

of the full-scale vehicle The model was mounted in close proximity to a ground plane simulating the dual-rail, high-speed test track at Holloman AFB, where the complex M-X guidance and control system will be tested

50 YEARS AGO — 1962

A gas-turbine prototype, the Rover

T4 is designed “with the possibility of

future production in mind.” The Rover

Co Ltd., which has been researching

gas-turbine engines for over 15 years,

says that considerable technical vances have been made, particularly in improved fuel consumption and throt-tle response to provide fast accelera-tion In addition to its unconventional powerplant, the four-passenger T4 has all-round independent suspension and

JANUARY 19, 2012

30

Trang 33

Need to build a device with a smaller footprint? Precise, repeatable performance?

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RS# 125

See us at SLAS, Booth #218 and MD&M, Booth #1878

Trang 34

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Mouser Electronics Inc., Dallas, a

design-engineering resource and

distributor of semiconductors and

electronic components, will

han-dle the distribution for the

follow-ing companies: National products

portfolio from Texas Instruments,

Dallas, an analog and digital conductor IC design and manu-facturing company; Android Open Accessory Development Boards

semi-from Microchip Technology,

Chandler, Ariz., a manufacturer of microcontroller and analog de-vices; advanced connectors and

sockets from Yamaichi

Electron-ics, San Jose, a supplier of

high-performance interconnection devices; and Duris E 3 LEDs from

Osram Opto Semiconductors,

Sunnyvale, Calif., a manufacturer

of optoelectronic semiconductors for the lighting, sensor, and visual-ization markets

Electronic-components distributor

Digi-Key Corp., Thief River Falls,

Minn., has been selected by the following companies to distribute

products: NOR Flash memory from

the U S subsidiary of Macronix

International Co Ltd., a

manufac-turer of integrated devices for the nonvolatile memory market; wire-less, embedded and Smart Energy

technology devices from MMB

Research, Toronto; the complete

portfolio of RTOS, protocol stack and utility products, and develop-ment tools for embedded systems

from Micrium, Weston, Fla.; and

lighting control and

energy-man-agement systems from Illumra

Self-powered Wireless Controls,

Orem, Utah

RS# 126 JANUARY 19, 2012

32

Trang 35

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Trang 36

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COMPANY NEWS

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The DDASCA Consortium

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PERSONNEL Cicoil, Valencia, Calif., has hired

Jon Hinkley as Western Regional Sales Manager Cicoil manufac-

tures silicone-jacketed, high-flex flat cables

Alan K Frost has been named

President of Carr Lane

Manufac-turing Co., St Louis Frost

suc-ceeds the late CEO Earl E Walker Carr Lane provides tooling com-ponents, clamps, fixturing, and related workholding products for all areas of manufacturing

ATW Companies Inc., Warwick,

R I., a provider of engineered metal-manufacturing products, has appointed Tracy MacNeal as Corporate Director of Business Development, where she will be responsible for coordinating and managing the strategic direction

of the entire organization through sales and marketing efforts

AWARDS Forest City Gear, Roscoe, Ill., a

manufacturer of precision gears, received the Workforce Develop-

ment Award from The Supplier

Excellence Alliance (SEA) at their

5th Annual Awards Event The awards recognize the performance and leadership contributions of small to midsized supplier com-panies SEA is an aerospace & de-fense nonprofit alliance

COMPANIES JOIN FORCES Haydon Kerk Motion Solutions,

Waterbury, Conn., and Pittman

Motors, Kent, Ohio, are now both

business units of Ametek

Preci-sion Motion Control, Kent, Ohio

Products offered by the two clude dc

in-brush and brushless motors, linear actuators, precision lead-screws, motorized and nonmotorized linear-rail and guide systems, drives, and control-lers, as well as motor products, in-cluding gearboxes, encoders, and

Trang 37

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EDITORIAL COMMENTARY

Time for engineers

to think about

unionizing?

It sometimes seems that professions and workers represented by unions do better than those without them Examples include school teachers, auto-workers, airline pilots, state-employed doctors and dentists, and a host of others So why haven’t more engineers jumped on the union bandwagon?Traditionally, engineers have a reputation for individualism and shy away from unions They seem to believe they can negotiate the pay and benefits they deserve And if they don’t like the compensation or working condi-tions, they can always get another job with better benefits Or at least that’s what they tell themselves

To get an idea of what unions are doing for engineers, I talked to a few

members of the Society of Professional Engineering Employees in

Aero-space (SPEEA), a union which represents 24,000 engineers working for Boeing and related companies Some of the major benefits of union mem-

bership, according to members I spoke with, are better pay and benefits They claim that while managers and other unrepresented workers have had

to take pay cuts and give back benefits, sometimes on short notice, SPEEA engineers have always gotten raises, both for seniority and merit, as per their contract

The union engineers and technicians say they also appreciate the security and peace of mind of a contract with well-defined policies governing pen-sions, hiring and layoffs, vacation, sick leave, and even overtime And they say the union, along with its lawyers, will see to it that management meets its contractual obligations This means management can’t fire union members

on a whim or without just cause

As one SPEEA member put it, “Many engineers say they are professionals and the company must treat them as such But you’re still labor and they can treat you as they see fit There’s nothing you can do about it except quit And

in this economy, that’s not always a good option, especially if you’re over 40 Heaven help you if you’re over 50 or 60.”

It’s true that if you accept an engineering position at Boeing or one of its related companies, you will be forced to join a union “But the $40 a month

it costs in dues is less than the benefits the union has negotiated,” says one 25-year Boeing worker “And although I’ve seen several engineers who were

a little grumpy at being lumped in with a union, they changed their tune when they ran into a problem with medical leave for taking care of a parent

or spouse, or had a beef with a manager, and the union stepped in to resolve the problem.”

The same Boeing engineer noted that outside IT people and other neering consultants who work at Boeing often confess to being jealous of the union’s benefits and contract package “They also wouldn’t mind having a say about company policies and projects similar to what we enjoy.”

engi-All the SPEEA folks I spoke with admit that any union is made up of people with different goals and opinions and that unions can have problems But they also say those relatively small problems can be ironed out They also agree that a good union does not want to hurt the company All SPEEA members I spoke with say they take great pride in Boeing and the planes and equipment the company designs and builds and want the company to survive and thrive

So why do you think engineers have avoided unions for all these years?

Trang 39

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ADVANCED MANUFACTURING

and crack-growth analyses were necessary

Aquila used a refined version of an existing element model to build the FE model of the longeron The company compared FEA results with physical test data “Using Femap with NX Nastran let us validate the model using measured strain data from a full-scale load test conducted years earlier,” says Aquila Engi-neering Manager Ben Terrell

finite-According to Terrell, the software has improved the company’s finite-element-modeling methods He credits the software’s large variety of specific preanaly-sis tools for model definition, as well as postanalysis tools for results “And the software makes it easy to sift through large amounts of engineering-results data with minimal effort and computer resources,” he says

“The software has boosted our modeling and cessing speeds by 50%,” says Terrell “Also, NX Nastran is a faster solver than we were previously us-ing Analyses are speedier due to NX Nastran’s capabil-ity to exploit a multicore processor.”

pro-Terrell estimates that the software’s increased speed and accuracy has cut design costs by tens of thousands of dollars since its purchase “We now have more confidence when tackling difficult problems and this attitude comes across in our interactions with customers Using Femap with NX Nastran has directly improved the quality of our work, as evidenced by a downturn in the need for prototyping and testing The software also helps us meet strict aircraft regulations,”

CAE for aerospace design

In the analysis of aircraft and aerospace structures,

several critical factors come into play Safety is

para-mount, modifications must comply with regulatory

requirements, and airplane manufacturers want

changes done in a cost-effective way Recently,

avionics engineering firm Aquila Engineering in

Australia found itself saddled with FEA software

that was no longer supported In its search for a new

program, the company needed software that could

import legacy models and offer an intuitive interface

so engineers using other FEA programs could quickly

learn the new software Also needed was good

prod-uct-specific training and ready access to

knowledge-able support technicians

Aquila opted for Femap FEA with the NX Nastran

base module from Siemens PLM Software, Plano,

Tex It also used CAE training services from Siemens

partner, Australian firm EnDuraSim.

According to Aquila, the software gave the

com-pany good compatibility between FEA and CAD and

met the company’s technical needs Femap with NX

Nastran lets users import geometry directly from NX

CAD to generate, in this case, FE models for analyzing

aircraft structures

A splice repair design for the upper longeron on

a particular aircraft was underway when Aquila

pur-chased the software FE analysis was needed to

pre-dict the loads in all the members as well as generate

rivet loads from the free-body diagrams for each part

Because the longeron undergoes a direct load, fatigue

The software has refined the mesh

in the area of the splice repair.

JANUARY 19, 2012

38

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