Handbook of Shaft Alignment Part 12 pdf

Base mounted through bracket to bearing housing of driver machine (a) Indicator block Probe mount Airframe tubing Stiffener Base mounted through bracket to bearing housing of driven machine Eddy probe driver (1 of 4) Extension cable (1 of 4) Eddy probe (2 of 4) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 520 6.10.2006 12:03am 520 Shaft Alignment Handbook, Third Edition Flexible coupling and shaft ends (b) The target bar can be attached to either the driver or the driven unit The probe bar can be attached to either the driver or the driven unit Proximity probe Proximity probe Proximity probe FIGURE 16.58 Alignment bar arrangements. (Upper diagram: Courtesy of Scientific Atlanta =SKF Condition Monitoring, San Diego, CA. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 521 6.10.2006 12:03am Measuring and Compensating for Off-Line 521 Advantages: . Fairly accurate measurements possible with proper setup. . Capable of measuring movement in vertical and horizontal directions. . Can continuously monitor positions of machinery without disturbing sensors or bars. . If the machinery is vibrating excessively when taking the running measurements, the proximity probes average the oscillation effectively to insure accurate distances between the probe tips and the targets. . Can be equipped to measure axial growth if desired. Disadvantages: . Knowledgeable, patient, and dedicated personnel required for successful measurements and evaluation of data. . Custom brackets and bars have to be designed, fabricated, and carefully installed on each machine case as close as possible to the centerline of rotation. . If the machinery is moving considerably from OL2R conditions, the proximity probes can bottom out on the target or move out of the linear range of the probes. . Thermal casing distortion where the probe and target bars are attached could result in data that are not representatives of the movement of the centerline of rotation of the shafts. . Somewhat expensive since custom braces and bars have to be fabricated; probes, cables, proximitors, readout devices, and power supplies have to be purchased. 16.15 APPLYING LASER–DETECTOR SYSTEMS FOR OL2R MEASUREMENTS Laser–detector systems can also be used to measure OL2R machinery movement in the machine case to machine case measurement category. In a very simple setup, where small amounts of relative movement between machinery cases is present, a laser (or laser–detector depending on what system you use) could be mounted at or near the centerline of rotation of one machine near the inboard bearing, and the detector (or prism depending on what system you use) could be mounted at or near the centerline of rotation of the other machine near its inboard bearing as shown in Figure 16.61. With the machinery off-line, the laser–detector system can be oriented to have the laser strike in the Probe bar Target bar “H”-shaped base to allow for positioning the bar in the up and down direction “H”-shaped base to allow for positioning the bar in the sideways direction End view of bars and probes Angle iron FIGURE 16.59 Fabricated alignment bar design. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 522 6.10.2006 12:03am 522 Shaft Alignment Handbook, Third Edition center of the detector targets. The laser–detector system is kept in place on the machine cases and the unit started up and operated until movement stops. If movement occurs between the machine cases, the laser will be striking at a different position in the photodetector. With the plethora of laser shaft alignment systems in existence, it is somewhat amazing to find out that very few people have tried to use their systems for this purpose. The underlying The probe and target bars can be mounted on either machine case but you have to know what is mounted where. The distances from the inboard feet to the points where the proximity probes are taking readings on the target bar must be known, as well as the orientation of the horizontal probes. The gap changes from off-line to running (or vice versa) need to be recorded. Remember to capture not only the amount of the gap change but also the direction (increasing gaps means the probe moved away from the target). Proximity probe alignment bar system Proximity probe alignment bar system Proximity probe alignment bar system Where is the bracket holding the probes mounted? compr Select the mounting location for the bracket that is holding the proximity probes (i.e., which machine will you attach the prox probe bracket to?). compr comprstm turb stm turb To operate this window stm turb stm turb stm turb OK compr Toward mils mils mils Vertical gap change mils 26 16 13 7 Vertical probes Horizontal probes Vertical probes Are the horizontal probes on the side of the target blocks? 5.5 2.5 in. in. in. 3 Enter the four distances shown. Determine the orientation of the target blocks with respect to the horizontal proximity probes and enter the direction. When done, press the “OK” button. in. 10 OK To operate this window North South Horizontal probes “Target” bracket “Target” bracket compr Lateral gap change Away Toward Away Toward Away Toward Away FIGURE 16.60 Alignment bar setup. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 523 6.10.2006 12:03am Measuring and Compensating for Off-Line 523 reluctance seems to originate from the difficulty in mounting the lasers and detectors to the machine cases. Since there is such a wide variation in machinery design, custom brackets are usually required to hold the equipment in place similar to those shown in Figure 16.62 and Figure 16.63. These brackets must not only hold the laser and detector in a stable position, but also the laser and detector need to have positional adjustments for centering the beam. Additionally, if laser–detector–prism systems or two single-axis laser–detector units are used, two sets of laser–detector prisms are needed to capture all the required information (vertical offset, vertical angularity, horizontal offset, and horizontal angularity). With mounts having a precise 908 rotation feature, one set of such two-axis equipment is sufficient. More detail on such mounts will be given later. Universal laser–detector mounting brackets can also be purchased as shown in Figure 16.64 through Figure 16.67. These brackets have the capacity to rotate the laser–detectors through a precise 908 arc to capture all of the measurements needed as mentioned previously, thus avoiding the need for two sets of laser–detector equipment. FIGURE 16.61 Basic setup of laser–detector systems used to measure OL2R movement. FIGURE 16.62 Laser–detector–prism systems setup on custom mounts measuring gear and compressor OL2R movement. Alignment bar setup also used for comparison. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 524 6.10.2006 12:03am 524 Shaft Alignment Handbook, Third Edition If a considerable amount of movement occurs between the machinery cases, the laser beam could potentially traverse outside of the detector target surface area, inhibiting complete and accurate OL2R measurements. Another type of laser–detector mounting system was created to overcome this problem and is referred to as the plug in back zeroing laser target (PIBZLT) mounts as shown in Figure 16.68 through Figure 16.75. These mounts have been designed such that it will allow attachment of different types of lasers, detectors, or prisms, with the capacity to remove and install them repeatably with good remounting precision. There is a ball pivot placed in between the laser–detector mounting plate and the machine case attach- ment plate with adjusting screws to tilt or pitch the laser or detector, enabling one to zero the FIGURE 16.63 Permalign systems mounted across coupling. (Courtesy of Pru ¨ ftechnik, Ismaning, Germany. With permission.) FIGURE 16.64 Permalign M3 brackets and laser–detector mounted across coupling. (Courtesy of Pru ¨ ftechnik, Ismaning, Germany. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 525 6.10.2006 12:03am Measuring and Compensating for Off-Line 525 laser–detector system. Tooling balls are placed at the twelve-, three-, six-, and nine o’clock positions on both the backing and mounting plates to measure the change in position of the mounts as shown in Figure 16.71. By measuring the position of the mounting and backing plates via the tooling balls with the machinery off-line, adjusting the laser–detector to rezero the beam, and then measuring the position of the mounting and backing plates via the tooling FIGURE 16.65 Permalign M3 brackets and laser–detector mounted across coupling. (Courtesy of Pru ¨ ftechnik, Ismaning, Germany. With permission.) FIGURE 16.66 Laser–detector OL2R mounts. (Courtesy of Vibralign Inc., Richmond, VA. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 526 6.10.2006 12:03am 526 Shaft Alignment Handbook, Third Edition balls with the machinery running, the OL2R movement can be measured. The tooling ball measurements taken with the PIBZLT system are based on the face–face measurement method (see Chapter 14 for reference). The back zeroing feature greatly extends the meas- urement range. It also corrects for laser target poor linearity if this is present (30%–40% linearity error found on some targets at range limits). Key considerations for capturing good readings: . The laser–detector mounts should be attached to each machine case as close as possible to the centerlines of rotation to accurately determine shaft motion, not casing expansion or bearing housing warpage. FIGURE 16.67 Laser–detector OL2R mounts. (Courtesy of Vibralign Inc., Richmond, VA. With permission.) FIGURE 16.68 Plug in back zeroing laser-target mounts. (Courtesy Murray & Garig Tool Works, Baytown, TX. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 527 6.10.2006 12:03am Measuring and Compensating for Off-Line 527 . Mounting devices must be stable and rigid enough to maintain a precise position of the lasers and detectors even under moderately long time periods with machinery running and vibration present. . Accurate positioning mechanisms for laser and detector required on mounting fixtures. FIGURE 16.69 Close-up of four-axis laser target on PIBZLT mount. (Courtesy Murray & Garig Tool Works, Baytown, TX. With permission.) FIGURE 16.70 Side view of PIBZLT mount. (Courtesy Murray & Garig Tool Works, Baytown, TX. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 528 6.10.2006 12:03am 528 Shaft Alignment Handbook, Third Edition . Capture a set of readings from OL2R conditions and another set of readings from R2OL conditions to determine if there is a consistent pattern of movement. Advantages: . Fairly accurate measurements possible with proper setup. . Capable of measuring movement in vertical and horizontal directions. . Can continuously monitor positions of machinery for moderate periods of time with stable fixtures. . If the machinery is vibrating excessively when taking the running measurements, the photodetector can average the position of the center of the ‘‘bouncing’’ laser beam fairly accurately. Disadvantages: . Knowledgeable, patient, and dedicated personnel required for successful measurements and evaluation of data. . Other light sources, steam, water vapor, etc. can affect the ability to capture accurate readings. . If the machinery is moving considerably from OL2R conditions, the laser beam can move out of the range of the photodiode surface area unless the mounts have the capability of getting positioned knowing what the before and after positions were (e.g., PIBZLT mounts). . Custom brackets have to be designed and fabricated or purchased and carefully installed on each machine case as close as possible to the centerline of rotation. . Possibility of inaccurate measurements due to uneven thermal distortion of machine case where the holding fixtures are attached. FIGURE 16.71 Taking micrometer measurements on tooling balls on PIBZLT system. The four-axis laser target is on the left mount and the laser source is on the right mount. (Courtesy Murray & Garig Tool Works, Baytown, TX. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 529 6.10.2006 12:03am Measuring and Compensating for Off-Line 529 [...]... off-line lateral motor shaft position Desired off-line lateral pump shaft position Scale: 10 in 10 mils FIGURE 16.89 Example of desired off-line side and top view alignment models of a motor and a pump to calculate the shoot for reverse indicator measurements Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 547 6.10.2006 12: 03am 547 Measuring and Compensating for Off-Line... movement of steam turbine and compressor (Courtesy Murray & Garig Tool Works, Baytown, TX With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 533 6.10.2006 12: 03am 533 Measuring and Compensating for Off-Line Off-line machinery positions Running machinery positions Center of inboard foot bolt Center of inboard foot bolt Backside of ball Center of Center of Backside... calculation based on the shaft positions shown in Figure 16.89 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 548 6.10.2006 12: 03am 548 16.18.4.2 Shaft Alignment Handbook, Third Edition Face–Rim Shoot for Dial Indicator Readings Figure 16.91 shows the desired off-line shaft positions of a motor and a pump in both the side and top views In this particular case, ‘‘front... Desired off-line vertical shaft positions Scale: 10 in 10 mils FIGURE 16.86 Example of a desired off-line side view (vertical) shaft position alignment model using the alignment bars or custom fixtures with proximity probes The desired off-line top view (lateral) shaft position alignment model is not shown alignment readings be if you were using the reverse indicator method, face–rim, double radial, shaft. .. set of readings from R2OL conditions to determine if there is a consistent pattern of movement Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 534 6.10.2006 12: 03am 534 Shaft Alignment Handbook, Third Edition FIGURE 16.77 BRTC system measuring OL2R movement of steam turbine and pump Advantages: Fairly accurate measurements possible with proper setup Capable of measuring... direction), the shaft centerlines should not be collinear when off-line Since the shafts should not be in line with each other when off-line, what should the off-line alignment measurements be to insure the shafts are in the desired offline positions similar to what is shown in Figure 16.86 through Figure 16.88 What would the Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page... feet, what positions the shafts should be in when off-line, and what are the ‘‘shoot for’’ readings What positions are the shafts actually in when off-line? How will the movement restrictions affect the final chosen alignment line? Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 553 6.10.2006 12: 03am 553 Measuring and Compensating for Off-Line Shaft to coupling spool... the off-line shaft- to -shaft centerline alignment process to compensate for this movement to insure collinear shaft centerlines during operating conditions Depending on how the OL2R data were collected, there are different procedures used to interpret the information to finally obtain the desired off-line shaft positions Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page... the shaft positions By varying the Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 536 6.10.2006 12: 03am 536 Shaft Alignment Handbook, Third Edition 1 Measure both verniers in the top and bottom positions off-line Measure both verniers in the top and bottom positions when running using a strobe light to “freeze” the vernier image 3 2 Measure both verniers in both of. .. the shafts in the desired off-line positions Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 549 6.10.2006 12: 03am 549 Measuring and Compensating for Off-Line Face–rim method Motor Multistage pump Side view Up Motor Multistage pump Where the dial indicator readings will be taken on the pump shaft 10 _ 0 + 10 20 20 30 30 40 50 40 Desired off-line vertical motor shaft . 4) Eddy probe (2 of 4) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 520 6.10.2006 12: 03am 520 Shaft Alignment Handbook, Third Edition Flexible coupling and shaft ends (b) The. of bars and probes Angle iron FIGURE 16.59 Fabricated alignment bar design. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 522 6.10.2006 12: 03am 522 Shaft Alignment. movement. Alignment bar setup also used for comparison. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 524 6.10.2006 12: 03am 524 Shaft Alignment Handbook, Third