Handbook Of Shaft Alignment Episode 2 Part 4 pot

reading. Draw a line from the point on the graph where the dial indicator captured the reading to the outboard end of that shaft. Remember, whatever shaft the dial indicator has captured the readings on, that is the shaft that will be drawn on the graph paper. Figure 10.9 shows an example of plotting a pump shaft onto the side view alignment model. 3. Next, at the intersection of the graph centerline and the point where the dial indicator has captured the smallest reading, plot a point above or below this intersection one-half of the top to bottom or side-to-side dial indicator reading. If the bottom (or side) reading was negative, place a point half of the bottom (or side) reading from the graph centerline toward the top of the graph. If the bottom (or side) reading was positive, place a point half of the bottom (or side) readings from the graph centerline toward the bottom of the graph (the same as in the point to point modeling techniques). Lay a straightedge from the point on the graph centerline where the bracket was held through the point on the graph where the dial indicator captured the reading. Draw a line from the point on the graph where the dial indicator captured the reading to the outboard end of that shaft. Figure 10.10 shows an example of plotting a motor shaft onto the side view alignment model. T B EW 0 T B E W 0 Motor Pump +28 –46 –10 Sag compensated readings –56 +24 +4 Motor Pump 5 in. Select a scale factor from top to bottom Up Side view Scale: 30 mils To select the appropriate up and down scale factor, start with the shaft that had the larger of the two bottom readings. In this example, it is the pump shaft. Pick an up and down scale factor that will keep the entire length of the pump shaft within the boundaries of the graph paper. Usually this scale factor will keep the motor shaft (which has the smaller bottom reading) within the boundaries of the graph paper also. Scale off half of the bottom reading on the pump here (where the dial indicator took the reading on the pump shaft) Then draw a line from here (where the bracket was located on the motor shaft and the graph centerline) through the scaled off point here The reading is negative so start at the graph centerline and plot up half this amount (28 mils) FIGURE 10.9 Plotting a pump shaft onto the side view alignment model. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 360 6.10.2006 12:14am 360 Shaft Alignment Handbook, Third Edition Notice that there is a consistency to this plotting technique. If the top to bottom or side-to-side dial indicatorreadingisnegative,plothalfofthereadingtowardthetopof the graph paper, for either shaft. If the top to bottom or side-to-side dial indicator reading is positive, plot half of the reading toward the bottom of the graph paper, for either shaft. The process for plotting the shaft in the top view is the same as it is in the side view. As discussed in Chapter 8, one of the cardinal alignment modeling rules is to zero the indicator on the side that is pointing to the top of your graph paper. Refer to Figure 10.7 where it states ‘‘view looking east.’’ Therefore, when looking at our drive system from above (i.e., the top view), the direction pointing to the top of the graph paper must be east. Figure 10.11 shows how the pump shaft is plotted in the top view and how the east side readings were zeroed to extract the west side readings on each shaft from the complete set of reverse indicator measurements. Figure 10.12 shows how the motor shaft is plotted in the top view. T B EW 0 T B E W 0 Motor Pump +28 –46 –10 Sag compensated readings –56 +24 +4 Motor Pump 5 in. Up Side view Scale: 30 mils Construct the position of the motor shaft based on the bottom reading captured by the dial indicator as shown If the graph is stripped away, here are the exaggerated relative positions of the motor and pump shaft centerlines The goal is to bring these shafts into alignment with each other. How many possible ways can you move these two shafts so they come in line with each other? Answer: There are an infinite number of ways to align two shafts when you consider that they are both movable! FIGURE 10.10 Plotting a motor shaft onto the side view alignment model. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 361 6.10.2006 12:14am Reverse Indicator Method 361 10.4 MODELING THE REVERSE INDICATOR METHOD USING THE LINE-TO-POINT TECHNIQUE There is an alternative method to graphing or modeling reverse indicator readings. There are two advantages of this technique as opposed to the point-to-point method: . Somewhat easier to model multiple element drive trains where reverse indicator readings were captured at two or more flexible couplings. . Regardless of whether you have an asymmetrical or symmetrical bracket arrangement, the points where the brackets are being clamped to the shaft are not relevant, only the points where the dial indicator readings are being captured are required. There are six pieces of information that you need to properly construct the shaft positions using this technique. Motor Pump 5 in. Scale: 20 mils Top view East T B EW 0 T B EW 0 Motor Pump +28 –46 + 46 = 0 –10 + 46 = +36 –56 +24 – 24 = 0 + 4 –24 = –20 T B EW 0 T B EW 0 Motor Pump 0 +36 0 –20 FIGURE 10.11 Plotting a pump shaft onto the top view alignment model. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 362 6.10.2006 12:15am 362 Shaft Alignment Handbook, Third Edition 1. The distance from the outboard-to-inboard feet (bolting planes) of the first machine. 2. The distance from the inboard bolting plane of the first machine to the point on the shaft where the dial indicator is capturing the rim readings on the first machine. 3. The distance from where the dial indicator is capturing the rim readings on the first machine to the point where the dial indicators are capturing the rim readings on the second machine. 4. The distance from where the dial indicator is capturing the rim readings on the second machine to the inboard bolting plane of the second machine. 5. The distance from the inboard-to-outboard feet (bolting planes) of the second machine. 6. The eight dial indicator readings taken at the top, bottom, and both sides on both shafts after compensating for sag (i.e., what a perfect, ‘‘no sag’’ bracket system would have measured). Accurately scale the distances along the length of the drive train onto the graph centerline as shown in Figure 10.13. The procedure for plotting the line-to-point reverse indicator technique is as follows: 1. Select one of the two machinery shafts and draw one of those shafts on top of the graph centerline. Figure 10.14 shows an example where the motor shaft was initially placed on Motor Pump 5 in. Scale: 20 mils Top view East T B EW 0 T B EW 0 Motor Pump 0 +36 0 –20 FIGURE 10.12 Plotting a motor shaft onto the top view alignment model. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 363 6.10.2006 12:15am Reverse Indicator Method 363 the graph paper centerline and the pump shaft position was plotted from the reverse indicator measurements. Figure 10.15 shows an example where the pump shaft was initially placed on the graph paper centerline and the motor shaft position was plotted from the same reverse indicator measurements. 2. Start with the top to bottom or side-to-side dial indicator readings on the other shaft (i.e., the one you did not draw on the graph centerline). 3. Plot the other shaft centerline position by starting at the intersection of the graph centerline and the point where the dial indicator was capturing the readings on the other shaft. If the bottom (or side) reading was negative, place a point half of the bottom (or side) readings from the graph centerline toward the top of the graph. If the bottom (or side) reading was positive, place a point half of the bottom (or side) readings from the graph centerline toward the bottom of the graph (the same as in the point-to-point modeling techniques). Do not draw any lines yet! 4. Next, start at the intersection of the graph centerline and the point where the dial indicator was capturing the readings on the shaft that was drawn on top of the graph centerline. If the bottom (or side) reading was negative, place a point half of the bottom (or side) readings from the graph centerline toward the bottom of the graph. If the bottom (or side) reading was positive, place a point half of the bottom (or side) readings 15 in. 5.5 in. 7 in. 10 in. 14.5 in. Motor Pump Motor Pump 5 in. 15 in. Up Side view Scale: 5.5 in. 7 in. 10 in. 14.5 in. 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 FIGURE 10.13 Dimensional information needed for plotting reverse indicator readings using the line- to-point plotting method. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 364 6.10.2006 12:15am 364 Shaft Alignment Handbook, Third Edition T B EW 0 T B E W 0 Motor Pump +28 –46 –10 Sag compensated readings –56 +24 +4 Motor Pump 5 in. Up Side view Scale: 30 mils Draw the motor shaft directly on the graph paper centerline Plot half of the bottom reading (14 mils) here Plot half of the bottom reading (28 mils) here FIGURE 10.14 Side view example where the motor shaft was initially placed on the graph paper centerline and the pump shaft position was then plotted. T B EW 0 T B EW 0 Motor Pump +28 –46 –10 Sag compensated readings –56 +24 +4 Motor Pump 5 in. Up Side view Scale: 30 mils Draw the pump shaft directly on the graph paper centerline Plot half of the bottom reading (14 mils) here Plot half of the bottom reading (28 mils) here FIGURE 10.15 Side view example where the pump shaft was initially placed on the graph paper centerline and the motor shaft position was then plotted. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 365 6.10.2006 12:15am Reverse Indicator Method 365 from the graph centerline toward the top of the graph (opposite of the point-to-point modeling technique). 5. These two points marked on the graph at the dial indicator reading points define the line of sight (i.e., the centerline of rotation) of the other shaft. Draw a straight line through these two points from the coupling end to the outboard end of the other shaft. To make your alignment corrections, refer to the Section 8.4.6 and Section 8.4.7. BIBLIOGRAPHY ‘‘Boiler and Machinery Engineering Report—Shaft Alignment for Rotating Machinery,’’ Section 4.0, #4.26, October, 1989, American Insurance Services Group, Inc., New York. Blubaugh, R.L. and Watts, H.J., Aligning rotating equipment, Chemical Engineering Progress, 65(4), 1969, 44–46. Dodd, V.R., Total Alignment, The Petroleum Publishing Company, Tulsa, OK, 1975. Dreymala, J., Factors Affecting and Procedures of Shaft Alignment, Technical and Vocational Depart- ment, Lee College, Baytown, TX, 1970. Durkin, T., Aligning shafts, Part I—measuring misalignment, Plant Engineering, January 11, 1979. King, W.F. and Peterman, J.E., Align Shafts, Not Couplings!, Allis Chalmers Electrical Review, 2nd Quarter, 1951, pp. 26–29. Motor Pump 5 in. Scale: 20 mils Draw the pump shaft directly on the graph paper centerline Plot half of the west reading (10 mils) here Plot half of the west reading (18 mils) here East Top view T B EW 0 T B EW 0 Motor Pump +28 –56 –10 +46 +36 –46 +46 0 +4 –24 -20 +24 –24 0 Hey! different scale factor in this view! Zero the indicator on the side that is pointing toward the top of the graph FIGURE 10.16 Top view example where the pump shaft was initially placed on the graph paper centerline and the motor shaft position was then plotted. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 366 6.10.2006 12:15am 366 Shaft Alignment Handbook, Third Edition Murray, M.G., Alignment Manual for Horizontal, Flexibly Coupled Rotating Machines, 3rd ed., Murray and Garig Tool Works, Baytown, TX, 1987. Murray, M.G., Choosing an Alignment Measurement Setup, Murray and Garig Tool Works, Baytown, TX, personal correspondence, October 12, 1979. Nelson, C.A., Orderly steps simplify coupling alignment, Plant Engineering, June 1967, pp. 176–178. Piotrowski, J.D., Alignment techniques, Proceedings Machinery Vibration Monitoring and Analysis Meeting, New Orleans, LA, June 26–28, 1984, Vibration Institute, Clarendon Hills, IL. Piotrowski, J.D., The Graphical Alignment Calculator, Machinery Vibration Monitoring and Analysis, Vibration Institute, Clarendon Hills, IL, 1980. Samzelius, J.W., Check points for proper coupling alignment, Plant Engineering, June 1952, pp. 92–95. Two Step Dial Indicator Method, bulletin no. MT-SS-04-001, Rexnord, Thomas Flexible Coupling Division, Warren, PA, 1979. Yarbrough, C.T., Shaft Alignment Analysis Prevents Shaft and Bearing Failures, Westinghouse Engineer, May 1966, pp. 78–81. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 367 6.10.2006 12:15am Reverse Indicator Method 367 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C010 Final Proof page 368 6.10.2006 12:15am 11 Face and Rim Methods Perhaps the first dial indicator technique used to align rotating machinery shafts is the face and rim or face–peripheral method shown in Figure 11.1. It is not entirely clear who initially used this technique or when and where it was employed to align rotating machinery shafts but this method is frequently referred in machinery installation manuals and coupling installation instructions and is still practiced by personnel who align machinery. It is similar to the way machinists center and square work pieces in lathes and mills and undoubtedly came from machining practices during the dawn of the industrial revolution. As shown in Figure 11.2, the face readings can be taken on either side of the coupling hub (or an object affixed to the other shaft). The accuracy of this method is directly related to the diameter the face readings are taken on as demonstrated in Figure 11.3. The larger the diameter of the face reading sweep, the more accurate this method becomes. Assuming that both shafts can be rotated, the face diameter can be increased by attaching an object to the one shaft and the face indicator placed against that object as shown in Figure 11.4. Advantages 1. This is a good technique to use in situations where one of the machinery shafts cannot be rotated or it would be difficult to rotate one of the machinery shafts (see also Chapter 12). 2. Many people who use this method understand that the rim (or diametral surface) dial indicator shows centerline offset or parallel misalignment and the face indicator indi- cates that an angular misalignment condition is present. 3. This is a good method to use when the face readings can be taken on a fairly large diameter (typically 8 in. or greater). This method begins to approach the accuracy of the reverse indicator technique whenever the diameter of the face readings equals or exceeds the span from the bracket location to the point where the rim indicator readings are being captured in the reverse indicator method. Disadvantages 1. Not as accurate as the reverse indicator method if both shafts can be rotated and particularly if the face measurements are taken on diameters less than 8 in. 2. If the machinery shafts are supported in sliding (plain or sleeve) bearings, it is very easy to axially float the shafts toward or away from each other when rotating the shafts results in bad or inaccurate face readings (see Section 6.10). 3. Bracket sag must be measured and compensated for. 11.1 MATHEMATICAL RELATIONSHIP IN MACHINERY ALIGNMENT Figure 11.8 shows the mathematical relationship between the machinery dimensions and the dial indicator readings captured using the face–rim method. The equations will solve for the moves that need to be made to correct the misalignment condition (i.e., bring the shafts into a Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C011 Final Proof page 369 6.10.2006 12:16am 369 [...]... Edition DK4 322 _C011 Final Proof page 379 6.10 .20 06 12: 16am 379 Face and Rim Methods Compensating for axial shaft float when capturing face readings 20 30 30 30 10 40 50 _ 0 + 10 40 20 20 10 40 50 _ 0 + 10 40 30 30 20 40 10 50 _ 0 + 40 10 30 10 40 50 _ 0 + 10 40 20 20 30 30 40 10 _ 0 + 50 30 10 30 30 10 40 50 _ 0 + 10 40 20 20 tate Ro 30 30 10 40 50 _ 0 + 10 40 20 20 30 30 20 40 10 50 _ 0 + 40 10 20 40 10... +2 S − 12 N B 0 30 20 40 10 50 _ 0 + 10 S −16 N Axial movement B −38 − (+6) + ( +2) 20 30 10 40 50 _ 0 + 10 40 20 30 20 30 30 20 40 10 40 50 _ 0 + 40 10 30 20 tate Ro Axial movement tate Ro 3 T 0 T S − 12 N B Indicator reads − 12 30 Axial movement 10 40 50 _ 0 + 10 40 20 20 −30 30 30 30 20 40 20 40 10 50 _ 0 + B 10 40 50 _ 0 + 40 10 S −16 10 Axial movement 30 30 0 T 20 tate Ro 4 Indicator reads +6 − 32. .. movement that occurs during the shaft alignment measurement process Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 380 6.10 .20 06 12: 16am 380 Shaft Alignment Handbook, Third Edition Motor Compressor Indicator set to zero 20 30 30 50 40 30 10 20 50 40 10 30 20 40 10 _ 0 + 10 40 30 50 _ 0 + 40 10 30 tate Ro Axial movement tate Ro 1 20 20 _ 0 + 10 40 20 Indicator set to zero... Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 3 72 6.10 .20 06 12: 16am 3 72 30 30 10 40 50 _ 0 + 10 40 30 30 20 20 20 10 40 50 _ 0 + 10 40 20 Shaft Alignment Handbook, Third Edition FIGURE 11.3 Taking face readings on different diameters will result in different readings even though the shafts are in the same angular position Piotrowski / Shaft Alignment Handbook, Third... DK4 322 _C011 Final Proof page 3 74 6.10 .20 06 12: 16am 3 74 Shaft Alignment Handbook, Third Edition 10 _ 0 + 10 20 20 30 30 20 30 30 10 40 50 _ 0 + 10 30 40 50 _ 0 + 40 10 30 _ 0 + 50 10 10 40 20 30 20 10 40 20 50 40 40 20 40 30 20 FIGURE 11.5 If the shafts are moving axially during the face measurement sweep, indicators can be positioned to observe the axial movement of each shaft to correct each face measurement... DK4 322 _C011 Final Proof page 373 6.10 .20 06 12: 16am 373 30 30 10 40 50 _ 0 + 10 40 20 20 Face and Rim Methods R 20 30 30 10 40 50 _ 0 + 10 40 20 te ota te ota R R R te ota te ota FIGURE 11 .4 Face readings can be captured on any surface or device rigidly attached to a shaft (assuming the shafts are rotated together) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 3 74. .. the bottom point This is Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 3 84 6.10 .20 06 12: 16am 3 84 Shaft Alignment Handbook, Third Edition Motor Pump 10 _ 0 + 10 20 20 30 30 20 30 10 40 50 _ 0 + 4 in Motor 40 30 10 12 in 50 40 20 40 8 in 9 in Side view 4 in 12 in 8 in Up 9 in 20 in Pump 20 in Scale: 5 in FIGURE 11.16 Dimensional information needed for plotting the face–rim...Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 370 6.10 .20 06 12: 16am 370 Shaft Alignment Handbook, Third Edition 10 _ 0 + 10 20 20 30 40 10 40 50 _ 0 + 10 40 20 50 30 40 20 Rim dial indicator 30 30 Face dial indicator • PROCEDURE • 1 Attach the alignment bracket firmly to one shaft and position the indicators on the face and diametral surface of the other shaft (or coupling... 40 20 20 30 30 20 40 10 50 _ 0 + 40 10 20 40 10 30 50 _ 0 + 40 10 30 FIGURE 11.11 Compensate for axial movement with stationary indicators 20 tate Ro tate Ro 20 20 40 10 40 50 _ 0 + 40 10 30 20 20 30 30 30 20 40 10 20 50 _ 0 + 40 10 30 20 20 30 20 40 10 20 50 _ 0 + 40 10 Axial movement tate Ro tate Ro 3 4 30 tate Ro 2 3 Again, rotate both shafts through a 90° rotation carefully observe each indicator... 11 .20 Face–rim top view example alignment model Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 387 6.10 .20 06 12: 16am Face and Rim Methods 387 FIGURE 11 .21 Murray & Garig Machinery Alignment Plotting Board FIGURE 11 .22 Artificial face split disk system (Courtesy of Murray & Garig Tool Works, Baytown, TX.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 . Edition 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 40 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 Compensating. position. Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C011 Final Proof page 3 72 6.10 .20 06 12: 16am 3 72 Shaft Alignment Handbook, Third Edition 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 R o t a t e R o t a t e R o t a t e R o t a t e FIGURE. Alignment Handbook, Third Edition 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 40 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 5 0 1 0 4 0 2 0 3 0 + _ 1 0 4 0 2 0 3 0 Compensating