Handbook Of Shaft Alignment Episode 3 Part 3 ppsx

Adjust the position of the target inside the bore of the cylinder by alternately loosening and tightening the adjustment screws at the 3 and 9 o’clock position to place the target half t

7 Using the optical micrometer, measure the positions of the targets at the near and farends of the far cylinder in the vertical and sideways directions Study and perform theinformation in Figure 19.22 Record the information.

TO PT

OP TO PT

OP Top Top

One-half of the original horizontal offset

One-half of the original vertical offset

Initia l position of target

Position of target after moving horizontally and vertically inside the cylinder

Step 4 Adjust the position of the target inside the bore of the cylinder by alternately loosening and tightening the target fixture adjustment screws at the 12 and 6 o’ clock position to place the target half the total vertical offset distance measured in step 3 above Adjust the position

of the target inside the bore of the cylinder by alternately loosening and tightening the adjustment screws at the 3 and 9 o’clock position

to place the target half the total lateral offset distance measured in step 3 above as shown in the figure below.

FIGURE 19.19 Step 4 for centering a target in a cylinder

TO PT

OP TO PT OP

TO PT OP

TO PT

OP

TO PT OP

Initial position of target

Position of target after the target was moved horizontally and vertically inside the cylinder

Top Top

Observed position

of target afte r adjusting vertical and lateral tangent screws on ji g

t ransi t

Step 5 Adjust the vertical and lateral tangent screws on the jig transit to center the telescope crosshairs in the center of the bore target as shown in the figure below.

Step 6 Repeat step 3 though step 5 until their target stays centered in the telescope crosshairs through 3608 of rotation.

FIGURE 19.20 Step 5 and step 6 for centering a target in a cylinder

630 Shaft Alignment Handbook, Third Edition

8 If the targets at the near and far ends of the far cylinder are not coincident (in line) withthe targets at the near and far ends of the near cylinder, position either the near or farcylinder to bring the bore centers into alignment Refer to the ‘‘correcting the misalign-ment’’ procedure below and study Figure 19.23 and Figure 19.24.

Use optical micrometer

to measure the offset at this target Step 1

Translation distance needed for correction = (Near to far target distance+near target to transit distance)*(offset at near target)

Near to far target distance

Rotate the jig transit to aim at the center of the far target then focus back

to see if the near target

is also centered

FIGURE 19.21 Bucking in your line of sight to the centerline of the bore of the cylinder

OK, so much for dumb luck The near and far targets are not directly in line with eachother What you have to do now is translate the entire jig transit in the sidewaysdirection and rotate the jig transit through its azimuth (Z) axis to align the verticalcrosshairs of the telescope with the vertical paired lines on the near target Similarly, youhave to raise or lower the jig transit in the vertical direction using the precision liftmechanism and plunge (i.e., pitch) the jig transit through its pivoting (X) axis to align thevertical crosshairs of the telescope with the horizontal paired lines on the near target Nowthere are two ways to do this: trial and error and mathematics Both work, mathematicsjust happens to be slightly faster but requires a little bit of number crunching.

Plug the scale target reading at the near target and the distances into the formula toobtain the necessary translation distances

2 Translate (i.e., move) the entire jig transit in the sideways direction to the amount youcalculated in the equation You can either use the rotary indicator wheel on thetranslation table where the scope is mounted or you can focus the scope on the neartarget, set the optical micrometer to the desired lateral translation distance (assuming it

is under 100 mils), and begin translating the scope until the crosshairs line up on the neartarget’s horizontal and vertical paired lines

Raise (or lower) the entire jig transit in the vertical direction the amount youcalculated in the equation by adjusting the vertical lift mechanism You can focus the

28 mils to the right

Near target in far cylinder

Far target in far cylinder

FIGURE 19.22 Measuring the amount of misalignment of the near and far targets in the far cylinder

632 Shaft Alignment Handbook, Third Edition

Far cylinder-far target

Far cylinder-near target

Far cylinder-near support

Near cylinder-near support

Near cylinder-far support

34 mils to the left

28 mils to the right

Far cylinder-far target

Far cylinder-near target

Far cylinder-near support

Near cylinder-near support

Near cylinder-far support

Overlay / final desired alignment line

scope on the near target, set the optical micrometer to the desired vertical translationdistance (assuming it is under 100 mils), and begin translating the scope until thecrosshairs line up on the near target’s horizontal and vertical paired lines.

3 Once you have translated the scope you must now rotate the scope through its azimuthaxis so your vertical crosshair lines back up with the vertical paired lines on the neartarget Similarly, you now must plunge or pitch the scope through its X-axis so yourhorizontal crosshair lines up with the horizontal paired lines on the near target

If everything works well, the telescope’s line of sight should be centered at the near and fartargets If not, repeat step 1 through step 3 until the telescope crosshairs and the centers ofboth targets are in line with each other At this point, the line of sight of the pivoting scope onthe jig transit is parallel to the bore centerline of the cylinder

19.6 CORRECTING THE MISALIGNMENT

Once the bore targets were centered in the far cylinder and the telescope’s line of sight wasbucked back into the centerline of the bore of the near cylinder, measurements were taken atthe near and far targets of the far cylinder To help visualize the misalignment between thetwo cylinders and assist in correcting the misalignment condition, construct side view and topview alignment models

As shown in Figure 19.22, assume that the following measurements were taken at the farcylinder targets:

Near target: 18 mils high and 28 mils to the right

Far target: 52 mils high and 34 mils to the left

Figure 19.23 shows an exaggerated misalignment condition between the near and far cylinders

in the side view (up or down direction) Figure 19.24 shows an exaggerated misalignmentcondition between the near and far cylinders in the top view (left or right direction) Notice thatthe target positions and bolting plane positions have been accurately scaled on the graph paperfrom left to right and the bore centerline of the far cylinder has been accurately scaled from top tobottom on the graph (see scale factors in lower left hand corner) Now a straight line can be drawn

on top of the graph and the cylinders can be moved to that overlay or final desired alignment line.19.7 LASER BORE ALIGNMENT SYSTEMS

Laser–detector systems as shown in Figure 19.25 through Figure 19.30 have been developed

to accomplish the task of bore alignment If you have not already done so, you might want toreview the information on lasers and photodiode detectors in Chapter 6 to get a basicunderstanding of how these components work

The principles of bore alignment with laser–detector systems are virtually identical to theprocess using optical alignment equipment explained in this chapter The laser beam is substi-tuted for the visual line of sight established with a jig transit Rather than visually observing asighting target placed in the center of a hollow cylinder, a photodiode is centered in thecylinder and a cable transmits the position of the laser beam on the surface of the detector

FIGURE 19.25 D630 Extruder system (Courtesy of Damalini, Molndal, Sweden With permission.)

FIGURE 19.26 D630 Linebore system (Courtesy of Damalini, Molndal, Sweden With permission.)

636 Shaft Alignment Handbook, Third Edition

FIGURE 19.27 Fixturlaser Extruder system (Courtesy of Fixturlaser, Molndal, Sweden With permission.)

FIGURE 19.28 Fixturlaser Centering system (Courtesy of Fixturlaser, Molndal, Sweden Withpermission.)

FIGURE 19.29 Pru¨ftechnik Boralign system (Courtesy of Pruftechnik, Ismaning, Germany Withpermission.)

FIGURE 19.30 Pru¨ftechnik Centralign system (Courtesy of Pruftechnik, Ismaning, Germany Withpermission.)

638 Shaft Alignment Handbook, Third Edition

20 Parallel Alignment

Chapter 18 covered alignment of V-belt-driven equipment As you observed, the goal ofaligning belts and sheaves is to get the driver shaft parallel to the driven shaft and the belts totrack straight in the sheaves To accomplish this task, the outer surfaces of the sheaves or thegrooves of the sheave itself were used as the reference positions The assumption is that theouter surfaces of the sheaves or the grooves of the sheave itself are perfectly perpendicular toits centerline of rotation To verify the perpendicularity of the sheave to its shaft, face runoutmeasurements are taken as shown in Figure 18.13 and Figure 18.15 Once we are sure that thesheaves are indeed perpendicular to their centerlines of rotation, we can then use straightedges, strings, wires, or laser beams to align the sheaves, bringing the two shafts into a parallelposition It seems cumbersome to use the sheaves as the reference positions but the shafts aretypically buried inside the machine casings, making it virtually impossible to use the shaftsthemselves to measure from If only the whole length of both shafts were exposed! Well, insome cases, they are

There are drive systems in industry that encompass a series of cylinders, shafts, or rollswhere they must be positioned so they are parallel to each other Examples of this arefrequently found in the paper, plastic, printing, and steel industry

20.1 ROUGH ALIGNMENT OF PARALLEL ROLLS

As a quick review, Figure 20.1 shows the coordinate system and terminology used in aligningcylinders or rolls The goal in aligning rolls is to get all rolls so that their individual y–z planesare parallel or coplanar and their x–z planes are parallel or coplanar

Perhaps the simplest method of measuring roll parallelism is to use a standard tapemeasure Effectively you wrap the tape measure around each roll, once at one end, recordthe distance around and between the two rolls there, then again at the other end as shown inFigure 20.2 and Figure 20.3 Compare the distance at the near and far ends If the measure-ments are the same, assuming both rolls are level with respect to gravity, the centerlines ofrotation of the rolls are parallel to each other

If however, the rolls are not level with respect to gravity, their y–z planes may be parallel,but the centerlines of rotation may not be parallel Figure 20.4 shows how the two tapemeasurement distances at the near and far end can be the same but the centerlines of rotation

of the rolls might not be parallel

Bear in mind that the x–z plane does not have to be referenced to gravity, that is, the x–zplane does not necessarily have to be level Remember, level and aligned do not mean thesame thing It is nice and convenient that the rolls are level but they do not have to be If theirslopes are the same (i.e., the x–z plane is not level, but at a fixed angle), placing the rollsparallel to each other is still achievable

639

y

x

Roll Pitch

FIGURE 20.1 Coordinate system for cylinders

Measure distance at near end

FIGURE 20.2 Using a standard tape to measure the distance between the rolls at the near end

Measure distance at far end

FIGURE 20.3 Using a standard tape to measure the distance between the rolls at the far end

640 Shaft Alignment Handbook, Third Edition

20.2 USING OPTICAL ALIGNMENT EQUIPMENT FOR ROLL PARALLELISMThe extreme accuracy and versatility of optical alignment equipment makes it ideal for use inaccurately positioning rolls for parallelism and perpendicularity To align the rolls inthe vertical, horizontal, and if necessary the axial direction, two instruments are needed,two telescopic transit squares or one telescopic transit square and a jig transit as shown inFigure 20.5 and Figure 20.6 The transit square has a second scope affixed to the yokes of thetransit that is at a precise 908 angle to the main sighting scope.

20.3 ALIGNING THE ROLLS IN THE VERTICAL (UP=DOWN) DIRECTIONFor this procedure you either need the telescopic transit square or a jig transit, a stand, and alateral translation slide

1 Setup the optical transit on its tripod or base so that your line of sight is slightly abovethe one of the shafts (or rolls) In this case, we set the equipment up to first observe theposition of the upper shaft (or roll) as shown in Figure 20.7

2 Level the scope Take a reading at scale target A and record the measurement Take areading at scale target B and record the measurement Measure the distance between thescale targets and their respective positions to the bearings that support both ends of theupper shaft (or roll) If the diameter of the roll is the same at both measurementpositions, and the readings at A and B are exactly the same, then the roll is level withrespect to gravity If the diameter of the roll is the same at both measurement positions,and the readings at A and B are not the same, then the roll has a slope with respect togravity Determine what the slope is by obtaining the difference between the measure-ments at A and B and divide it by the distance between target A and target B This willtell you the slope in mils=inch (or mils=foot if you prefer)

3 Move the optical equipment so you can sight along the top of the lower shaft (or roll)

as shown in Figure 20.8 Level the scope Take a reading at scale target C and recordthe measurement Take a reading at scale target D and record the measurement.Again, measure the distance between these scale targets and their respective positions

to the bearings that support both ends of the lower shaft (or roll) It is convenient,but not necessary that the distance between scale targets A and B is the same as thedistance between scale targets C and D If the diameter of the roll is the same at bothmeasurement positions, and the readings at C and D are exactly the same, then the roll islevel with respect to gravity If they are not the same, determine the slope as described

4 By comparing the difference between the readings you observed at scale targets A and Band the difference between the readings you observed at scale targets C and D, you will

be able to determine if the rolls are parallel to each other in the up–down direction

20.4 ALIGNING THE ROLLS IN THE LATERAL (SIDE TO SIDE) DIRECTIONFor this procedure you need either a telescopic transit square and a jig transit or twotelescopic transit squares, a stand with lateral translation slides for each instrument, and alight source for one transit

1 The best way to perform this procedure is to use two telescopic transit squares or onetelescopic transit square and a jig transit Setup the telescopic transit square on its stand

so that your line of sight is slightly to one side of one of the shafts (or roll) as shown inFigure 20.9 This transit will be referred to as the measurement transit

FIGURE 20.5 Telescopic transit square (Courtesy of Brunson Instruments Co., Kansas City, MO.With permission.)

642 Shaft Alignment Handbook, Third Edition

2 Level the telescopic transit square Position scale targets on the side of the shaft (or roll)

at both ends as shown in Figure 20.9 Measure the distance between the scale targets andtheir respective positions to the bearings that support both ends of the lower roll Youshould also measure the distance from the nearest scale target to the center of theuniversal transit square (i.e., where it rotates through its azimuth axis) Loosenthe locking screw that will allow the pivoting telescope to rotate through the X axis.What you are going to do now is position the universal transit square so the pivot-ing telescope’s line of sight is parallel to the shaft (or roll) as shown in Figure 20.10and Figure 20.11

FIGURE 20.6 Jig transit (Courtesy of Brunson Instruments Co., Kansas City, MO With permission.)

3 Take a reading at scale target E and record the measurement Take a reading at scaletarget F and record the measurement If you are really lucky, the readings at scale targets

E and F are exactly the same (i.e., the telescope’s line of sight is parallel to the roll)

4 OK, so much for dumb luck The readings at scales E and F are not the same What youhave to do now is translate the entire universal transit square in the X direction androtate the universal transit square through its azimuth (Y) axis so the pivoting telescopesline of sight is parallel to the lower shaft (or roll) Now there are two ways to do this,trial and error or mathematics Both will work, but mathematics just happens to beslightly faster and requires a little bit of number crunching

Optical jig transit or universal transit square

Line of sight

Optical scale target B Optical

scale target A

Lower shaft (or roll)

Upper shaft (or roll)

Y Z

X

FIGURE 20.7 Observing the vertical position of the upper roll

Optical scale target D Optical

scale target C

Lower shaft (or roll)

Upper shaft (or roll)

Line of sight

Optical jig transit or universal transit square

FIGURE 20.8 Observing the vertical position of the lower roll

644 Shaft Alignment Handbook, Third Edition