Steady rest for rotating shaft

Abstract

An improved steady rest assembly having a pair of opposed gripper arms that selectively open and close around a rotating cylindrical workpiece. One end of the gripper arms includes a workpiece-engaging member while the opposite end is pivotally coupled to a stationary base portion. Each gripper arm has a precision cut camming groove located between the two ends. A linearly translating yoke carries a third workpiece-engaging member and a pair of camming pins that slidably mates with these camming grooves to open and close the gripper arms. As the yoke moves toward a workpiece, the three workpiece-engaging members close around and center the workpiece.

1 . A steady rest for gripping a rotating workpiece, comprising:
 a non-moving base; and   a gripping assembly comprising:
 a pair of opposed gripper arms that selectively open and close around said workpiece, one end of the gripper arms includes a workpiece-engaging member while the opposite end is pivotally coupled to said base, wherein each gripper arm includes a pair of opposed precision cut camming walls, which define a camming slot, located between the two ends; and 
 a yoke which is slidably mounted upon said base and which carries a third workpiece-engaging member and a pair of camming pins, each camming pin is slidably mated within one of said camming slots to open and close said gripper arms; 
   wherein said gripping assembly is movable between an open position where the three workpiece-engaging members are remote from the workpiece and a closed position where the three work-engaging members abut and center the workpiece.   
   
   
       2 . A steady rest as defined in  claim 1 , wherein each of said gripping arms comprise:
 a pair of parallel arm plates which are separated by and sandwich said yoke, each of said arm plates including a cam slot;   wherein said camming pin slidably mates with and aligns both of said cam slots, which cooperatively define one of said camming slots.   
   
   
       3 . A steady rest as defined in  claim 2 , wherein said camming pins include two roller bearings, wherein each of said roller bearings is received within and abuts one of said arm plate cam slots. 
   
   
       4 . A steady rest as defined in  claim 1 , wherein said yoke comprises:
 a push plate; and   a body having two shoulders at opposite ends of said body, said body is mounted to said push plate whereby said shoulders project away from said push plate.   
   
   
       5 . A steady rest as defined in  claim 1 , further comprising:
 actuator means coupled to said yoke and which cause said yoke to translate linearly relative to said base.   
   
   
       6 . A steady rest as defined in  claim 1 , in which said workpiece-engaging members each comprise a roller. 
   
   
       7 . A steady rest as defined in  claim 1 , wherein each of said gripping arms have an inner side wall and an outer side wall, and wherein each of said camming slots is concave-shaped relative to said outer side wall. 
   
   
       8 . In a workpiece gripping apparatus, a combination comprising:
 a stationary housing;   a yoke having a center workpiece-engaging member extending from one end of said yoke and a pair of outwardly projecting shoulders, said first workpiece-engaging member is flanked on two sides by said shoulders, wherein said workpiece-engaging member is mounted within a center bore having a centerline and each shoulder includes a camming pin bore having a camming pin centerline which runs parallel to and co-planar with said center bore centerline;   a pair of camming pins having two concentrically mounted roller bearings, each camming pin is mounted within and extends from one of said camming pin bores whereby each roller bore is located on opposite sides of said shoulder; and   a pair of elongated gripping arms, said gripping arms terminating at one end at an outer work-engaging member, each gripping arm includes a pivot point at the end opposite to the outer work-engaging member, each gripping arm comprising:
 a pair of identical parallel spaced arm plates, each arm plate including a pair of opposed arcuate camming walls, which define a cam slot located between the pivot point and the end terminating at the outer work-engaging member; 
 said spaced arm plates sandwich said shoulders and said roller bearings abuttingly engage said camming walls in one of said spaced arm plates; and 
 a pivot pin mounted to said pivot point and to said body; 
   wherein said yoke is linearly moveable within said housing, effective to cause said roller bearing to engage said camming walls and rotate said gripping arms about said pivot pins.   
   
   
       9 . A combination as defined in  claim 8 , wherein said yoke further comprises a push plate which extends away from center work-engaging member. 
   
   
       10 . A combination as defined in  claim 9 , further comprising actuator means coupled to said push plate and which cause said yoke to translate linearly relative to said housing. 
   
   
       11 . A combination as defined in  claim 8 , in which said workpiece-engaging members each comprise a roller. 
   
   
       12 . A combination as defined in  claim 8 , wherein each of said arm plates have an inner side wall and an outer side wall, and wherein each of said cam slots is concave-shaped relative to said outer side wall. 
   
   
       13 . A method of forming an economical steady rest for holding a rotating workpiece, comprising the steps of:
 forming an arcuate precision cam slot into an elongated arm plate between a pivot bore and a work-engaging end in only a single cutting process;   providing a yoke having a work-engaging member at one end and a pair of shoulders flanking said work-engaging member;   sandwiching a pair of said arm plates around each of said shoulders to form a pair of gripping arms;   mounting a pivot pin through said shoulder and said cam slots of each gripping arm;   pivotally mounting said gripping arms to a base at said pivot bores; and   slidably mounting said yoke to said base, whereby said gripping arms rotate about said pivot bore and follow said cam slot as said yoke is translated along said base.   
   
   
       14 . A method as defined in  claim 13 , wherein said single cutting process is a laser cutting process. 
   
   
       15 . A method as defined in  claim 13 , further comprising the steps of:
 mounting a linear actuator to base; and   coupling said linear actuator to said yoke, effective to cause said yoke to translate linearly along said base.