Handbook Of Shaft Alignment Episode 1 Part 7 doc

Disadvantages: . Requires lubrication . Temperature limitation due to lubricant . Difficult to calculate reaction forces and moments of turbomachinery rotors when using these couplings since the values for the coefficient of friction between the gear teeth vary considerably Coupling hubs and sleeves on shafts Coupling hubs and sleeves on spool FIGURE 4.8 Two different variations of gear couplings employing a spool piece. Sleeve Gear tooth in “pivoted” position Gear tooth in “tilted” position Centerline of sleeve Centerline of coupling hub (with gear teeth) FIGURE 4.9 Tilted and pivoted positions of the gear teeth in its sleeve. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 150 6.10.2006 5:43pm 150 Shaft Alignment Handbook, Third Edition 4.4.1.3 Metal Ribbon Couplings The metal ribbon coupling was introduced around 1919 by Bibby Co. Metal ribbon couplings consist of two hubs with axial ‘‘grooves’’ on the outer diameter of the hub where a continuous S-shaped grid meshes into the grooves. Misalignment and axial movement is achieved by flexing and sliding of the grid member in specially tapered hub ‘‘teeth.’’ . Capacity: up to 70,000 hp=100 rpm . Maximum recommended speed: to 6000 rpm . Shaft bores: to 20 in. . Shaft spacing: to 12 in. Tilted position Pivoted position Pivoted position Tilted position Pivoted position FIGURE 4.10 Gear tooth tracking pattern when subjected to misalignment conditions. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 151 6.10.2006 5:43pm Flexible and Rigid Couplings 151 . Special designs and considerations: Grid fabricated from hardened, high-strength steel. Close coupled hubs with removable spacer available. Advantages: . Easy to assemble and disassemble . Long history of successful applications . Torsionally soft Disadvantages: . Requires lubrication . Temperature limited . Speed limited 4.4.1.4 Universal Joint Couplings Perhaps the oldest flexible coupling in existence is the universal joint coupling. This coupling is also known as the Cardan or Hooke joint. The basic design consists of U-shaped shaft ends with a hole drilled through each ‘‘U’’ to accept a ‘‘þ’’ shaped cross. If one universal joint is used to connect two shafts together, then only pure angular misalignment can exist where the centerlines of rotation intersect at the center of the ‘‘þ’’ shaped cross. For a flexible coupling to accept both parallel and angular misalignment, there FIGURE 4.11 Metal ribbon type coupling. (Courtesy of Falk Corporation, Milwaukee, WI. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 152 6.10.2006 5:43pm 152 Shaft Alignment Handbook, Third Edition must be two flexing points. Therefore most universal joint couplings have two cross=yolk assemblies as illustrated in Figure 4.12 and Figure 4.13. When one universal joint is used it is important to recognize that variations in angular velocity will occur between the two connected shafts often referred to as the ‘‘Cardan error.’’ Sinusoidal motion will occur in the axial and torsional directions, producing axial vibration and torsional (i.e., twisting) vibration particularly if the torque is transmitted and the rotational speed is high. When two universal joints are used it is important to recognize that sinusoidal motion will also occur in the axial and torsional directions if the ‘‘entrance’’ and ‘‘exit’’ angles are not the same as shown in Figure 4.13. When these angles are the same in both planes, perfect kinematic balance exists across the coupling, canceling the torsional and thrust variance. 4.4.1.5 Flexible Link The flexible link coupling utilizes a series of cross laced, metallic links with one end of each link attached to a disc mounted on the driven shaft and the other end of each link attached to a disc mounted on the driver shaft. The links are matched in pairs so that when one is in tension, the other is in compression. Misalignment and axial displacement is accomplished by a flexing action in the series of cross links. FIGURE 4.12 Universal joint. (Courtesy of Zurn Industries, Erie, PA. With permission.) a a a a w ≠ w Correct assembly and set up Incorrect assembly and set up Yoke ears not in proper orientation on connector shaft Angle not the same as other end With a single universal joint, if the input and output shafts are not in line, a variation of the output shaft speed (w ) will result called Cardan error. When two universal joints are used where the entrance and exits angles are the same with the yokes aligned properly, the system is kinematically balanced producing synchronous shaft rotation at the input and output ends. FIGURE 4.13 Universal joint basics. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 153 6.10.2006 5:43pm Flexible and Rigid Couplings 153 . Capacity: up to 1100 hp=100 rpm. . Maximum recommended speed: to 1800 rpm. . Shaft bores: up to 20 in. . Shaft spacing: close coupled or 100 mm spacer with certain designs. FIGURE 4.14 Flexible link coupling. (Courtesy of Eaton Corporation, Airflex Division, Cleveland, OH under license from Dr. Ing. Geislinger & Company, Salzburg, Austria. With permission.) FIGURE 4.15 Leaf spring coupling. (Courtesy of Eaton Corporation, Airflex Division, Cleveland, OH. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 154 6.10.2006 5:43pm 154 Shaft Alignment Handbook, Third Edition . Special designs and considerations: An axial ‘‘fixation’’ device can be installed to prevent any axial movement if desired. Different designs can accommodate unidirectional or bidirectional rotation. Advantages: . No lubrication required Disadvantages: . Limited axial movement . Limited misalignment capabilities (can accept pure angular misalignment only) 4.4.1.6 Leaf Spring This coupling employs a series of radially positioned sets of leaf springs attached to an outer drive member and indexed into axial grooves in the inner drive member. The chamber around each spring set is filled with oil. When the spring pack is deflected, damping occurs as the oil flows from one side of the spring pack to the other. . Capacity: up to 15,000 hp=100 rpm . Maximum recommended speed: 3600 rpm . Shaft bores: up to 12 in. . Shaft spacing: up to 40 in. . Special designs and considerations: Designed primarily for diesel and reciprocating machines. Capable of transmitting shock torque values substantially higher than other couplings until springs reach their maximum allowable angular movement where the radial stiffness increases substantially. Various spring stiffnesses can be installed in each size coupling to properly match the torsional requirements to the drive system. Advantages: . Torsionally soft with good damping characteristics . Freedom of axial shaft movement FIGURE 4.16 Pin drive type coupling. (Courtesy of David Brown Gear Industries, Agincourt, Ontario, Canada. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 155 6.10.2006 5:43pm Flexible and Rigid Couplings 155 Disadvantages: . Requires lubricant for damping . Temperature limitations due to lubricant . Torsional characteristics change drastically with loss of oil 4.4.1.7 Pin Drive A series of metal pins with leaf springs are placed near the outer diameter where they engage into a series of holes bored into both shaft hubs. Some pin designs consist of a pack of flat springs with cylindrical keepers at each end that act as the flexing element in the coupling design. The spring sets can swivel in the pin connection to allow movement across the width of the spring set. . Capacity: up to 3800 hp at 100 rpm . Maximum recommended speed: to 4000 rpm . Shaft bores: to 13 in. . Shaft spacing: close coupled (1=8to1=2 in.). . Special designs and considerations: Drive pins can be fabricated to accommodate various torsional flexibility requirements and are indexed into oil impregnated bronze bushings in the coupling hubs. Advantages: . Can accommodate up to 1=2 in. of axial displacement . No lubrication required Disadvantages: . Limited offset misalignment capability 4.4.1.8 Elastomeric Couplings A wide variety of design variations that employ an elastomeric medium to transmit torque and accommodate misalignment as illustrated in Figure 4.17. Most of these couplings are torsionally ‘‘soft’’ to absorb high starting torques or shock loads. . Capacity: up to 67,000 hp=100 rpm but varies widely with design . Maximum recommended speed: approximately 5000 rpm (varies widely with design) . Shaft bores: up to 30 in. . Shaft spacing: up to 100 in. (varies widely) . Special designs and considerations: A considerable amount of inventiveness and ingenuity has been applied to this type of coupling design through the years as evidenced by the large array of design variations. The elastomeric medium is generally natural or synthetic rubber, urethane, nylon, teflon, or oil-impregnated bronze. As the elastomer is markedly softer than the hubs and solid-driving elements (wedges, pins, jaws, etc.), wear is minimal and replacement of the elastomer itself is all that is usually needed for periodic servicing. Advantages: . Minimal wear in coupling . Acts as vibration damper and isolator Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 156 6.10.2006 5:43pm 156 Shaft Alignment Handbook, Third Edition FIGURE 4.17 Elastomeric couplings. [Courtesy of (a and b) Lovejoy Corporation, Downers Grove, IL; (c) Holset Engineering Company, Cincinnati, OH; (d) T.B. Wood’s Sons, Chambersburg, PA. With permission.] (continued ) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 157 6.10.2006 5:44pm Flexible and Rigid Couplings 157 FIGURE 4.17 (continued) FIGURE 4.18 Contoured diaphragm coupling: (a) cutaway view of the flexible disk at one end of the coupling; (b) entire coupling. (Courtesy of Kopflex Corporation, Baltimore, MD. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 158 6.10.2006 5:44pm 158 Shaft Alignment Handbook, Third Edition . Acts as electrical shaft current insulator in some designs . Torsionally ‘‘soft’’ . Accepts some axial movement and dampens axial vibration . No lubrication required Disadvantages: . Speed limited due to distortion of elastomer from high centrifugal forces, causing imbal- ance . Deterioration of elastomer from temperature, oxidation of rubber, corrosive attack from undesirable environment . Potential safety hazard if elastomeric member releases from drive elements . Some designs may cause undesirable axial forces . Heat generated from cyclic flexing of elastomer 4.4.2 METALLIC MEMBRANE=DISK-TYPE COUPLING DESIGNS 4.4.2.1 Diaphragm Couplings Transmission of power occurs through two flexible metal diaphragms, each bolted to the outer rim of the shaft hubs and connected via a spacer tube. Misalignment and axial displacement is accomplished by flexing of the diaphragm members. . Capacity: up to 30,000 hp . Maximum recommended speed: up to 30,000 rpm . Shaft bores: up to 7 in. . Shaft spacing: 2 to 200 in. . Special designs and considerations: Metal diaphragm couplings are a highly reliable drive component when operated within their rated conditions. Exceeding the maximum allowable angular or parallel misalignment values or axial spacing will eventually result in disc failure. As the diaphragm is, in effect a spring, considerations must be given to the axial spring rate and vibration characteristics to insure that the diaphragm coupling natural frequency does not match rotating speeds or harmonics in the drive system. Advantages: . Excellent balance characteristics . No lubrication required . Low coupling weight and bending forces on shafts when operated within alignment limits . Accepts high temperature environment Disadvantages: . Limited axial displacement and oscillation . Proper shaft spacing requirements are generally more stringent than other coupling types . Excessive misalignment will transmit high loads to shafting Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 159 6.10.2006 5:44pm Flexible and Rigid Couplings 159 [...]... 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 — 0.09 375 0 .12 500 0 .18 75 0 0.25000 0.25000 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 0.04688 0.06250 0.09 375 0 .12 500 0 .15 625 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000... 5.50000 6.50000 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 No 10 No 10 0.25000 0. 312 50 0. 375 00 0. 375 00 0.50000 0.50000 0.62500 0 .75 000 0 .75 000 0. 875 00 1. 00000 All dimensions are given in inches Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 17 0 17 0 6 .10 .2006 5:44pm Shaft Alignment Handbook, Third Edition... 0.09 375 0 .12 500 0 .12 500 0 .18 75 0 0. 218 75 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 6.50000 7. 50000 9.00000 7. 50000 9.00000 11 .00000 1. 75 000 2.00000 2.50000 1. 75 000 2.00000 2.50000 1. 50000 1. 50000 1. 75 000 0. 875 00 1. 00000 1. 25000 0 .75 000 0 .75 000 0. 875 00 Over All dimensions are given in inches Square keys preferred for shaft dimensions above line rectangular keys below Source : Machinery's Handbook, 21st... Hydrocarbon Process., 56(3), 13 7 14 4, 19 77 Calistrat, M.M., Extend gear coupling life, Part 1, Hydrocarbon Process., 57 (1) , 11 2 11 6, 19 78 Calistrat, M.M., Extend gear coupling life, Part 2, Hydrocarbon Process., 11 5 11 8, 19 79 Centrifugal Pumps for General Refinery Services, API Standard 610 , American Petroleum Institute, Washington, D.C., March 19 71 Chander, T and Biswas, S., Abnormal wear of gear couplings—A... 25(4), 20–22, 19 83 Woodcock, J.S., Balancing criteria for high speed rotors with flexible couplings, Intl Conf Vib Noise in Pump, Fan and Compressor Installations, Sept 16 18 , 19 75 , University of Southampton, UK, C 112 =75 , pp 10 7 11 4 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 17 8 17 8 6 .10 .2006 5:44pm Shaft Alignment Handbook, Third Edition Wright, J., Which shaft coupling... 15 +10 −0 33 CL 5 CL 0 .75 0 1. 000 +0 −4 +3 −0 7 CL 0 +0 −4 +0 15 +10 −0 34 CL 5 CL 1. 000 1. 500 +0 −4 +4 −0 8 CL 0 +0 −4 +0 15 +10 −0 34 CL 5 CL 1. 500 3.000 +0 −5 +4 −0 9 CL 0 +0 −5 +0 15 +10 −0 35 CL 5 CL 3.000 4.000 +0 −6 +4 −0 10 CL 0 +0 −6 +0 15 +10 −0 36 CL 5 CL 4.000 6.000 +0 −8 +4 −0 12 CL 0 +0 −8 +0 15 +10 −0 38 CL 5 CL 6.000 7. 000 +0 13 +4 −0 17 CL 0 +0 13 +0 15 +10 −0 43 CL 5 CL Key dimensions... nonlubricated couplings, Hydrocarbon Process., 56(2), 12 3 12 5, 19 77 Broersma, G (Ed.), Couplings and Bearings, Part I Couplings, H Stam, Culemborg, 19 68, pp 1 82 Brown, H.W., A reliable spline coupling, J Eng Ind., Trans ASME, 10 1(4), 4 21 426, 19 79 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 17 6 17 6 6 .10 .2006 5:44pm Shaft Alignment Handbook, Third Edition ¨ Buhlmann, E.T and... 54(4), 19 1 19 3, 19 75 Wright, C.G., Tracking down the cause of coupling failure, Mach Des., 49 (14 ), 98 10 2, 19 77 Zirkelback, C., Couplings—a user’s point of view, Proc Eighth Turbomachinery Symp., Nov 19 79 , Texas A&M University, College Station, TX, pp 77 – 81 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C005 Final Proof page 17 9 5 26.9.2006 8:36pm Preliminary Alignment Checks In Chapter 1, ... +0 15 +10 −0 32 CL 5 CL 0 .75 0 1. 000 +0 −3 +3 −0 6 CL 0 +0 −3 +0 15 +10 −0 33 CL 5 CL 1. 000 1. 500 +0 −3 +4 −0 7 CL 0 +0 −3 +0 15 +10 −0 33 CL 5 CL 1. 500 2.500 +0 −4 +4 −0 8 CL 0 +0 −4 +0 15 +10 −0 34 CL 5 CL 2.500 3.500 +0 −6 +4 −0 10 CL 0 +0 −6 +0 15 +10 −0 34 CL 5 CL Type of Key rectangular — 0.500 +0 −3 +2 −0 5 CL 0 +0 −3 +0 15 +10 −0 33 CL 5 CL 0.500 0 .75 0 +0 −3 +3 −0 6 CL 0 +0 −3 +0 15 +10 ... Table 4.2) TABLE 4 .1 Key and Keyway Sizes for Various Shaft Diameters Nominal Key Size Height (H) Nominal Shaft Diameter Nominal Keyseat Depth (H/2) To (inclusive) Width (W) Square Rectangular Square Rectangular 0. 312 50 0.4 375 0 0.56250 0. 875 00 1. 25000 1. 375 00 1. 75 000 2.25000 2 .75 000 3.25000 3 .75 000 4.50000 5.50000 0.4 375 0 0.56250 0. 875 00 1. 25000 1. 375 00 1. 75 000 2.25000 2 .75 000 3.25000 3 .75 000 4.50000 5.50000 . (W) 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 1. 75 000 2.00000 2.50000 Square 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 1. 75 000 2.00000 2.50000 Rectangular — 0.09 375 0 .12 500 0 .18 75 0 0.25000 0.25000 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 50000 1. 50000 1. 75 000 Square 0.04688 0.06250 0.09 375 0 .12 500 0 .15 625 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 Rectangular — 0.04688 0.06250 0.09 375 0 .12 500 0 .12 500 0 .18 75 0 0. 218 75 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 0 .75 000 0 .75 000 0. 875 00 Nominal. (W) 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 1. 75 000 2.00000 2.50000 Square 0.09 375 0 .12 500 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 1. 50000 1. 75 000 2.00000 2.50000 Rectangular — 0.09 375 0 .12 500 0 .18 75 0 0.25000 0.25000 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 50000 1. 50000 1. 75 000 Square 0.04688 0.06250 0.09 375 0 .12 500 0 .15 625 0 .18 75 0 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 0.62500 0 .75 000 0. 875 00 1. 00000 1. 25000 Rectangular — 0.04688 0.06250 0.09 375 0 .12 500 0 .12 500 0 .18 75 0 0. 218 75 0.25000 0. 312 50 0. 375 00 0.4 375 0 0.50000 0 .75 000 0 .75 000 0. 875 00 Nominal. Directory Over 0. 312 50 0.4 375 0 0.56250 0. 875 00 1. 25000 1. 375 00 1. 75 000 2.25000 2 .75 000 3.25000 3 .75 000 4.50000 5.50000 To (inclusive) 0.4 375 0 0.56250 0. 875 00 1. 25000 1. 375 00 1. 75 000 2.25000 2 .75 000 3.25000 3 .75 000 4.50000 5.50000 6.50000 Key