Abstract:
A vibration damper has a pair of rollers that engage a shaft rotating about its longitudinal axis while being supported at its ends on centers. The rollers transmit shaft vibrations to the piston rod of a hydraulic or pneumatic cylinder in such a manner that the piston rod dampens the vibrations.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority of Provisional Patent Application filed May 30, 2003, Serial No. 60/474,137 for VIBRATION DAMPENER FOR ROTATING SHAFT. 
     
    
     
       BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    Steel shafts, such as an axle, are commonly finished by being mounted on a pair of rotating centers. The rotating shaft sometimes generates harmonic vibrations. Such vibrations are undesirable for achieving a precision finish on the shaft surface.  
           [0003]    The broad purpose of the present invention is to provide a damping device for reducing the vibrations of a rotating shaft. In the preferred embodiment of the invention, a pneumatic or a hydraulic power cylinder is mounted on a base, adjacent the rotating position of the shaft. The axis of the cylinder is aligned with and at a right angle to the centerline of the shaft. The piston rod is connected to a clevis which in turn is connected to a slide plate. The slide plate moves with the piston rod and either toward or away from the shaft. A pair of pivotal arms, mounted on the base, are cammed by the slide plate.  
           [0004]    Rollers mounted on the outer ends of the arms engage the workpiece, accommodating any misalignment of the workpiece. The slide plate carries a pair of cam rollers that are mounted in cam slots in the two arms. The arrangement is such that any vibration of the workpiece is transmitted through the arms, the plate slide and to the cylinder which dampens the vibrations.  
           [0005]    Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0006]    The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views and in which:  
         [0007]    [0007]FIG. 1 is an elevational view of a vibration damper illustrating the preferred embodiment of the invention;  
         [0008]    [0008]FIG. 2 is a view similar to FIG. 1, but showing some internal components in phantom;  
         [0009]    [0009]FIG. 3 is an enlarged view of one of the arms as seen from the left-side of FIG. 2;  
         [0010]    [0010]FIG. 4 is an enlarged view as seen along line  4  of FIG. 2;  
         [0011]    [0011]FIG. 5 is an enlarged view as seen along line  5  of FIG. 2;  
         [0012]    [0012]FIG. 6 is an enlarged view as seen along line  6  of FIG. 2;  
         [0013]    [0013]FIG. 7 is a plan view of the base separated from the remainder of this device; and  
         [0014]    [0014]FIG. 8 is an elevational view of the slide plate. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring to the drawings, FIGS. 1 and 2 illustrate a preferred vibration damper  10 . The vibration damper includes a cushioning pneumatic power cylinder  12 , such as a global series cylinder, double acting, single rod model, mounted in a vertical position on a suitable mounting bracket  14 , illustrated in phantom. The power cylinder has a pair of ports  16  and  18  connected to a source of pneumatic pressure, not shown, for reciprocating an internal piston, not shown. A clevis  20  is attached to a piston rod  21  to reciprocate toward or away from the centerline of an elongated workpiece  22 . The workpiece may be a shaft or an axle undergoing a metal finishing operation. The levis is movable along an axis  24  either toward or away from the center of workpiece  22 .  
         [0016]    Referring to FIGS. 4 and 7, a right angle base  26  has one wall  28  attached by fastener means  30  to the upper end face of the cylinder. Wall  28  has an opening  32  to accommodate the up and down movement of the clevis.  
         [0017]    Referring to FIGS. 4-6 and  8 , a slide plate  34  has a lower end connected to the clevis by a pin  36  such that as the clevis is moved by the power cylinder toward the workpiece, the slide plate moves an equal distance.  
         [0018]    The slide plate has a vertical slot  38  aligned with axis  24  of piston rod  21 .  
         [0019]    Referring to FIG. 4, a shoulder screw  40  and a jam nut  42  are supported in a horizontal position to base  26 . Screw  40  extends through slot  38  in the slide plate to the base.  
         [0020]    Referring to FIGS. 2, 5 and  8 , the slide plate has a pair of openings  44  and  46  located on opposite sides of slot  38 . A pair of dowel (pivot) pins  48  and  50  are mounted in the two openings  46  and  44 , respectively. Pins  48  and  50  are both mounted on the base.  
         [0021]    Elongated pivot arms  52  and  54  are pivotally mounted on pivot pins  48  and  50 , respectively. Arm  52  is pivotally movable from a lower release position, illustrated at A in FIG. 1, to an upper work-engaging position, illustrated in phantom at B. Similarly, arm  54  is pivotally movable from a lower release position C to an upper work-engaging position D. Arm  52  has a cam slot  56 . Arm  54  has a cam slot  58 . Cam slots  54  and  56  are each aligned with the center of their respective pivot pins.  
         [0022]    Referring to FIGS. 2 and 6, the slide plate carries a cam roller  60  which is disposed in cam slot  58 . As the slide plate rises toward workpiece  22  in a vertical motion, as viewed in FIG. 2, cam roller  60  rises along a linear path of motion from a lower position, illustrated in phantom in FIG. 2, toward an upper position also illustrated in phantom. Cam roller  60  moves in cam slot  58 , camming arm  54  from its lower position toward its upper position.  
         [0023]    Referring to FIGS. 1 and 2, a pair of floppy brackets  62 , only one shown, are pivotally mounted by a pin  63  on the outer end of pivot arm  54 . Workpiece-engaging rollers  64  and  66  are mounted in a spaced position on the outer end of brackets  62  by roller pins  68  and  70 , respectively. Dowel pin  72 , carried by the brackets, engages a channel  74  carried on arm  54  to limit the swing of rollers  64  and  66  about pin  63 .  
         [0024]    Referring to FIGS. 2 and 6, the slide plate has a second roller or cam follower  75  carried in cam slot  56 , camming arm  52  from a lower position, illustrated in solid in FIG. 2, to a raised position, also illustrated in phantom toward the workpiece.  
         [0025]    Referring to FIGS. 2 and 3, a second pair of floppy brackets  76  and  77 , similar to brackets  62 , are mounted by a pivot pin  78  on the outer end of arm  52 . The brackets carry a pair of rollers  80  and  82  on pins  84  and  86 , respectively, for engaging the workpiece. A dowel pin  88  carried by brackets  76  and  77  engages a channel-shaped cut-out in arm  52  to limit the pivotal motion of rollers  80  and  82  as they swing about the outer end of the arm  52 .  
         [0026]    Thus it is to be understood that I have described a vibration-dampening device for reducing the vibration of an elongated rotating workpiece  22 . Usually the workpiece will be delivered to a mounting position between arms  52  and  54 , and placed on rotating centers. Arms  52  and  54  are pivoted toward the workpiece until rollers  80 ,  82 ,  64  and  66  engage the workpiece at  900  intervals, as illustrated in FIG. 2.  
         [0027]    The floppy brackets which carry rollers  80 ,  82 ,  64  and  66  permit the two arms to be self-aligning to accommodate irregularities in the workpiece shape.  
         [0028]    In use, the damper is mounted, at a suitable location along a workpiece. The piston rod moves the slide plate in a vertical motion, rising to move the rollers either toward the workpiece, or lowering to move the arms toward this lower position to separate the cam rollers from the workpiece. Any vibration of the workpiece is transmitted through the arms and slide to the piston rod where the vibration is cushioned.