Handbook Of Shaft Alignment Episode 3 Part 2 pot

conditions as shown in the lower illustration in Figure 18.17. Adjustments to the machines may therefore require precise, controlled moves in the vertical, lateral, and axial directions. 18.9 USING A STRAIGHTEDGE TO MEASURE MISALIGNMENT Belt and sheave driven equipment poses a slightly different type of alignment problem than equipment directly coupled together. The basic objective is to insure that the shaft centerlines are parallel to each other. FIGURE 18.12 Rim runout check on sheave. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 600 28.9.2006 7:15pm 600 Shaft Alignment Handbook, Third Edition For decades, the most widely used alignment tool is either a string or a straightedge. Today there are far more elaborate ways to perform belt–sheave alignment as shown later in this chapter, but most often, acceptable belt alignment can be accomplished using a simple straightedge. Bear in mind that most manufacturers of belt and sheave drives suggest that the sheaves should be aligned to within 1=8 in. per foot distance between shaft centerlines. That is about 11 mils=in., much more forgiving that direct drive systems, which are typically aligned to around 1 mil=in. FIGURE 18.13 Face runout check on sheave. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 601 28.9.2006 7:15pm Aligning V-Belt Drives 601 Straightedges work fine for distances under 4 ft but when the distance between the driver shaft and the driven shaft begin to exceed that, a string should probably be used. One tool developed by Max Roeder called the A-String works extremely well and produces very accurate results shown in Figure 18.18 and Figure 18.19. The A-String has an adjustable base that enables one to compensate for centerline offset of sheaves as shown in Figure 18.20. To properly align sheaves, you must compensate for any difference in the actual center of the V in each sheave. Measure the width of the groove; then measure the flange outer thickness on each sheave to determine what the offset may have to be if the outer flange widths are not the same. FIGURE 18.14 Rim runout check on sheave. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 602 28.9.2006 7:15pm 602 Shaft Alignment Handbook, Third Edition FIGURE 18.15 Face runout check on sheave. FIGURE 18.16 Bent sheave. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 603 28.9.2006 7:15pm Aligning V-Belt Drives 603 18.10 MEASURING THE MISALIGNMENT AT THE SHEAVES To measure the amount of offset, pitch, and skew that exists between the shafts and their sheaves, measurements with a straightedge need to be taken at two different places on the outer surface of the sheaves as shown in Figure 18.21. Measure the distances across each sheave at the upper and lower gap measurement locations. Determine what type of gap condition you have based on the four different configurations shown in Figure 18.22. Using feeler gauges, measure and record the amount of the gaps (in mils) between the straightedge and the surface of the sheaves as shown in Figure 18.23 and Figure 18.24. 18.11 V-BELT MACHINE MEASUREMENTS In addition to the gap measurements taken on the sheaves as shown in Figure 18.21 through Figure 18.24, dimensional measurements of the two machines need to be taken as shown in Offset—the shafts are parallel to each other and in the X−Y plane but one shaft/sheave is to the right of left of the other shaft/sheave in the Y direction Pitch—the shafts are in the X−Y plane but one shaft/sheave is rotated through the Z-axis Skew—the shafts are not in the same plane and one shaft/sheave is rotated through the X-axis X Y Z Combination—this is the most common type of misalignment condition (and the most complex) where the shafts are not in the same plane and one shaft/sheave is rotated through both the X- and Z-axis FIGURE 18.17 (See color insert following page 322.) Types of belt and sheave misalignment conditions. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 604 28.9.2006 7:15pm 604 Shaft Alignment Handbook, Third Edition Figure 18.25. A recording sheet shown in Figure 18.26 can be used to record all the required information to generate an alignment model of the misalignment condition. 18.12 MODELING V-BELT ALIGNMENT PROBLEMS Alignment models can also be used to visualize the misalignment condition on belt and sheave drive equipment. You will have to generate two different views of your drive system. One view will be generated from above (i.e., the top view), which will show any offset and pitch conditions between the two sheaves. The end view will show any offset and skew conditions that exist between the two sheaves. You can use two T-bar overlays (see Face–Rim graphing method on Chapter 11) to represent each shaft=sheave. FIGURE 18.18 A-String sheave alignment tool. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 605 28.9.2006 7:15pm Aligning V-Belt Drives 605 18.13 V-BELT ALIGNMENT MODELING SAMPLE PROBLEM Figure 18.27 shows an electric motor driving a fan. The critical dimensions needed to generate an alignment model of this drive system are shown in Figure 18.27. Use one of the T-bar overlays to scale off the distance from the inboard-to-outboard bolts of the motor (15 in.) and the distance from the inboard bolt of the motor to the edge of the sheave where the straight- edge measurements are taken (5 in.). On the top of the T-bar overlay, scale off the 6 in. distance to represent where the straightedge gaps or contact point were measured. Similarly for the fan, use the other T-bar overlay to scale off the distance from the inboard-to-outboard bolts of the fan (12 in.) and the distance from the inboard bolt of the fan to the edge of the sheave where the straightedge measurements are taken (4 in.). On the top of the T-bar overlay, scale off the 8 in. distance to represent where the straightedge gaps or contact points were measured. FIGURE 18.19 A-String sheave alignment tool. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 606 28.9.2006 7:15pm 606 Shaft Alignment Handbook, Third Edition Figure 18.28 shows the top view of the motor and fan shafts. Notice that you want to pitch each T-bar overlay at the midpoint between the gap you measured at the top of each sheave and the gap you measured at the bottom of each sheave. In the case of the motor sheave gaps, the upper gap was 10 mils and the lower gap was 16 mils. (10 þ16 mils ¼ 26 mils; 26 mils=2 ¼ 13 mils, i.e., the midpoint). In the case of the fan sheave gaps, the upper gap was 26 mils and the lower gap was 8 mils. (26 þ 8 mils ¼ 34 mils; 34 mils=2 ¼ 17 mils, i.e., the midpoint). Notice that the motor shaft and fan shaft are not parallel to each other. Figure 18.29 shows the end view of the motor and fan shafts. In this view, the motor is toward us and the fan is away from us. Also notice that in this particular case, the distance from the upper to lower straightedge measurements on the motor was 6 in., the same distance the straightedge measurements were taken from the inboard-to-outboard edge of the motor as shown in the top view. If the distance from the upper to lower straightedge measurements is not the same as it was between the inboard and outboard edges, you must scale off whatever the upper to lower straightedge measurements actually were when viewing the shafts and sheaves in the end view. Again, notice that you want to pitch each T-bar overlay at the midpoint between the gap you measured at the top (upper edge) of each sheave and the gap you measured at the bottom (lower edge) of each sheave. In the case of the motor sheave gaps, the upper gap was 10 mils and the lower gap was 16 mils. The midpoint at the upper edge of the motor sheave is 5 mils, and the midpoint at the lower edge of the motor sheave is 5 mils. The T-bar for the motor should be pitched to intersect the midpoint at its upper and lower Sheave outer flange width is different FIGURE 18.20 Measuring centerline offset of sheaves. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 607 28.9.2006 7:15pm Aligning V-Belt Drives 607 points. In the case of the fan sheave gaps, the upper gap was 26 mils and the lower gap was 8 mils. The midpoint at the upper edge of the fan sheave is 13 mils, the midpoint at the lower edge of the fan sheave is 4 mils. The T-bar for the fan should be pitched to intersect the midpoint at its upper and lower points. Why do we position the T-bar overlays at the midpoints of the gaps? Because the actual centerline of rotation is midway between the 6 in. (on the motor) and 8 in. (on the fan) measurement points where the straightedge was positioned on each sheave. Graphically, the top of the T-bar overlay is represented as a straight line. When viewing the sheaves from the top or end views, the sheaves would actually appear as ellipses. Straightedge ____ inches ____ inches ____ inches _ ___ inches Straightedge Sheave measurement distances with straightedge in upper position Sheave measurement distances with straightedge in lower position Upper to lower straightedge separation distances across each sheave ___ inches ___ inches FIGURE 18.21 Measure the gap conditions on the sheaves at two different locations. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 608 28.9.2006 7:15pm 608 Shaft Alignment Handbook, Third Edition FIGURE 18.22 Four possible gap conditions. Upper position gap readings ___ mils ___ mils ___ mils ___ mils ___ mils ___ mils ___ mils ___ mils Determine where the straightedge is touching on each sheave. Measure and record the gaps on each sheave in one of the four conditions below. Touching or gap? FIGURE 18.23 Measure the gap conditions at the top of the sheaves. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C018 Final Proof page 609 28.9.2006 7:15pm Aligning V-Belt Drives 609 [...]... measurements on the inside of a cylinder FIGURE 19.4 Double radial method measuring outside and inside of cylinders Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 622 622 26 .9 .20 06 8:43pm 04 05 Far indicator Near indicator Shaft Alignment Handbook, Third Edition 04 02 02 01 + 0 _ 05 04 03 03 04 03 03 02 02 01 01 _ + 0 01 12 in View looking east 5 in 56 in 24 in Far indicator... Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C018 Final Proof page 616 616 28 .9 .20 06 7:15pm Shaft Alignment Handbook, Third Edition FIGURE 18 .33 SheaveMaster system (Courtesy of Ludeca Inc., www.ludeca.com, Doral, FL With permission.) FIGURE 18 .34 D200 BTA Digital system (Courtesy of Damalini AB, Molndal, Sweden With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C018... you were measuring the outside diameter FIGURE 19 .2 Motor and barrel Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 621 26 .9 .20 06 8:43pm 621 Bore Alignment Centerline of barrel is in line only with the end of the motor shaft Centerline of rotation Centerline of barrel FIGURE 19 .3 Pure angular misalignment of motor shaft and barrel centerline For example, with the... in T W + 52 0 E W +38 B 20 mils FIGURE 19.7 Top view alignment model of motor centerline and barrel centerline Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 624 624 26 .9 .20 06 8:43pm Shaft Alignment Handbook, Third Edition FIGURE 19.8 Coordinate optical micrometer (Courtesy of Brunson Instruments, Kansas City, MO With permission.) enabling visual sighting of targets... misalignment problem as shown in Figure 19 .3 619 Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 620 620 26 .9 .20 06 8:43pm Shaft Alignment Handbook, Third Edition View looking down the axis of rotation through clear shafts FIGURE 19.1 View through the axis of rotation One way to accomplish this measurement is to perform the double radial method (refer to Chapter 12) ... Co., publication number 575000 -3= 86 Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 619 19 26 .9 .20 06 8:43pm Bore Alignment The alignment of rotating machinery shafts, as discussed in the previous chapters, concentrates on measuring the centerline of rotation of one shaft with respect to another shaft These shafts are usually solid cylinders of various lengths supported... Jig transit Line of sight Far adjustment plane of far cylinder Near adjustment Far adjustment plane of far plane of near cylinder cylinder Near adjustment plane of near cylinder FIGURE 19.14 Line of sight observing two misaligned cylinders in the side and top views Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C019 Final Proof page 628 628 26 .9 .20 06 8:43pm Shaft Alignment Handbook, Third... 2 in or 20 mils 12 mils north Scale: 2 in or 20 mils Motor 18 mils south FIGURE 18 .30 (See color insert following page 32 2. ) Possible alignment corrections for the motor and fan in the top view Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_ C018 Final Proof page 615 28 .9 .20 06 7:15pm 615 Aligning V-Belt Drives Motor end view Looking south from motor end Up aft Motor sh 18 mils up Fan shaft. .. measure a 20 Figure 19.5 shows the dimensions and double radial measurements that were taken on the motor and barrel Figure 19.6 and Figure 19.7 show the side and top view alignment models 10 _ 0 + 10 20 20 Near indicator 30 30 40 50 40 10 Far indicator _ 0 + 10 20 20 30 30 40 50 40 Taking measurements on the outside of a cylinder 40 50 40 40 30 30 20 10 _ 0 + 10 Far indicator 20 50 40 30 30 20 20 10 _... Edition DK 4 32 2_ C019 Final Proof page 6 23 26 .9 .20 06 8:43pm 6 23 Bore Alignment Barrel Up Side view Motor Far indicator Near indicator 0 T 0 T 36 E Scale: 10 in 20 mils W Ϫ14 +24 E W +16 B 20 B +10 Sag compensated readings FIGURE 19.6 Side view alignment model of motor centerline and barrel centerline Figure 19.8 These sighting targets are fabricated from nylon with an accurately painted pattern of paired . following page 32 2.) Types of belt and sheave misalignment conditions. Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_C018 Final Proof page 604 28 .9 .20 06 7:15pm 604 Shaft Alignment Handbook, . A-String sheave alignment tool. Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_C018 Final Proof page 606 28 .9 .20 06 7:15pm 606 Shaft Alignment Handbook, Third Edition Figure 18 .28 shows. dimensions of the machinery FIGURE 18 .25 Dimensional measurements of the machines. Piotrowski / Shaft Alignment Handbook, Third Edition DK 4 32 2_C018 Final Proof page 610 28 .9 .20 06 7:15pm 610 Shaft Alignment