Self-centering stock support

Abstract

A mounting stock support or support jig assembly is disclosed for use in the manufacture of large, symmetrical hollow welded metal vessels having openings in one end, particularly exemplified by conventional hollow concrete mixing drums for transit concrete mixing trucks. The device is fully mechanized and automatically centers a cradled drum or other vessel for turning or rotation in the cradle and completion of welding assembly and other tasks requiring accurate centered rotation of the vessel such as machining roller tracks.

1 . A self-centering stock support or support jig for use in processing large symmetrical hollow vessels that have a central opening at one end including drums for transit concrete mixing trucks comprising:
 (a) a central shaft assembly;   (b) an expandable grabber assembly mounted on said central shaft including a substantially round head plate carrying an array of radially distributed, radially extendable vessel-grabbing fingers operable in unison to center and retain a vessel about said shaft using said opening;   (c) a mounting system for retaining and enabling the rotation of said support jig assembly with rotation of said central shaft assembly; and   (d) a mechanized finger operating system for extending and retracting said grabbing fingers.   
   
   
       2 . An apparatus as in  claim 1  wherein said finger operating system further comprises a centrally mounted tubular sleeve member and linkage connected between said tubular sleeve member and said vessel-grabbing fingers, said tubular sleeve member being reciprocally operable along said central shaft assembly. 
   
   
       3 . An apparatus as in  claim 2  wherein said central shaft assembly includes hollow shaft members and wherein said finger operating system further includes a draw bar member mounted within said hollow shaft members and connected to operate said tubular sleeve member reciprocally along said central shaft assembly, thereby extending and retracting said vessel-grabbing fingers. 
   
   
       4 . An apparatus as in  claim 3  wherein each of said vessel-grabbing fingers is mounted to operate along a radially disposed slot in said round head plate and including a radially disposed cam slot mounted on said round head plate next to each of said grabbing fingers, each of said grabbing fingers being further provided with a pair of attached follower members which ride in a corresponding cam slot as each said vessel-grabbing finger extends or retracts radially. 
   
   
       5 . An apparatus as in  claim 3  wherein said draw bar is operated by a pair of fluid-operated cylinders. 
   
   
       6 . An apparatus as in  claim 5  wherein said fluid-operated cylinders are hydraulic cylinders. 
   
   
       7 . An apparatus as in  claim 3  wherein said shaft assembly includes a bearing sleeve assembly which allows said hollow shaft members to rotate. 
   
   
       8 . An apparatus as in  claim 1  wherein said vessel-grabbing fingers are provided with a series of stepped notches to accommodate a plurality of vessel opening sizes. 
   
   
       9 . An apparatus as in  claim 1  wherein the number of extendable vessel-grabbing fingers is four. 
   
   
       10 . An apparatus as in  claim 4  wherein the number of extendable vessel-grabbing fingers is four. 
   
   
       11 . An apparatus as in  claim 4  wherein said vessel-grabbing fingers are provided with a series of stepped notches to accommodate a plurality of vessel opening sizes. 
   
   
       12 . An mounting system as in  claim 1  wherein said hollow vessel is a mixing drum for a transit concrete mixer truck.