Tool assembly having a two part body

Abstract

A tool assembly ( 10 ) such as a hammer assembly, includes a housing ( 11 ) defining a chamber ( 16 ) and a reciprocating piston ( 18 ) arranged in the chamber for cyclical movement in a work stroke and a return stroke. The housing ( 11 ) includes a lower housing member ( 14 ), an upper housing member ( 12 ) and an engaging structure ( 50 ) which permits the engagement of the upper housing member with the lower housing member by relative rotation of the upper and lower housing members, such that each of the lower and upper housing members ( 14, 12 ) defines a portion of the chamber ( 16 ). The upper housing member is a precision component which contains the hydraulic components or other drive components necessary to drive the piston, while the lower housing member can be manufactured separately since it does not need to be manufactured to the high tolerances required by the upper housing member. The resulting tool assembly may be more compact than a conventional tie rod tool assembly.

1 . A tool assembly comprising a housing defining a chamber and a reciprocating piston arranged in the chamber for cyclical movement in a work stroke and a return stroke, 
 wherein the housing includes a lower housing member, an upper housing member and engaging structure which permits the engagement of the upper housing member with the lower housing member by relative rotation of the upper and lower housing members, each of the lower and upper housing members defining a portion of the chamber.    
   
   
       2 . A tool assembly according to  claim 1 , further including a drive which moves the piston in a work stroke and a return which moves the piston in a return stroke in a direction opposite to that of the work stroke.  
   
   
       3 . A tool assembly according to  claim 2 , further including a work tool at least part of which is retained in the chamber, wherein the drive is a first hydraulic pressure source which moves the piston in a work stroke toward the work tool and the return is a second hydraulic pressure source which moves the piston in a return stroke away from the work tool.  
   
   
       4 . A tool assembly according to  claim 1 , wherein the engaging structure includes mutually engaging protrusions on the upper and lower housing members.  
   
   
       5 . A tool assembly according to  claim 1 , further including a prestressing structure adapted to urge the lower housing member away from the upper housing member.  
   
   
       6 . A tool assembly according to  claim 5 , wherein the engaging structure includes an upwardly facing mating surface of the lower housing member adapted to engage with a downwardly facing mating surface of the upper housing member, the prestressing structure being arranged to urge the mating surfaces against each other.  
   
   
       7 . A tool assembly according to  claim 6 , wherein the prestressing structure comprises at least one jacking screw.  
   
   
       8 . A tool assembly according to  claim 7 , wherein the at least one jacking screw is engaged in a threaded aperture in the upper housing member and is adapted to engage with an upwardly facing bearing surface of the lower housing member.  
   
   
       9 . A tool assembly according to claims  7 , wherein the prestressing structure comprises a plurality of jacking screws arranged around the perimeter of the upper housing member.  
   
   
       10 . A tool assembly according to  claim 6 , wherein the prestressing structure comprises at least one tension screw.  
   
   
       11 . A tool assembly according to  claim 10 , wherein the prestressing structure further includes a compression sleeve urged by tension applied by said at least one tension screw into compressive contact with a bearing surface on the lower housing member.  
   
   
       12 . A tool assembly according to  claim 11 , wherein the compression sleeve includes at least one sleeve member having a resilient deflector flange.  
   
   
       13 . A tool assembly according to  claim 1 , wherein the engaging structure includes a bayonet coupling.  
   
   
       14 . A tool assembly according to  claim 1 , wherein the engaging structure includes mutually engaging helical protrusions on the upper and lower housing members.  
   
   
       15 . A hydraulic hammer comprising a tool assembly, wherein the tool assembly includes a housing defining a chamber and a reciprocating piston arranged in the chamber for cyclical movement in a work stroke and a return stroke, 
 wherein the housing includes a lower housing member, an upper housing member and engaging structure which permits the engagement of the upper housing member with the lower housing member by relative rotation of the upper and lower housing members, each of the lower and upper housing members defining a portion of the chamber.    
   
   
       16 . A hydraulic hammer according to  claim 15 , further including drive structure which moves the piston in a work stroke and return structure which moves the piston in a return stroke in a direction opposite to that of the work stroke.  
   
   
       17 . A hydraulic hammer according to  claim 16 , further including a work tool at least part of which is retained in the chamber, wherein the drive structure is a first hydraulic pressure source which moves the piston in a work stroke toward the work tool and the return structure is a second hydraulic pressure source which moves the piston in a return stroke away from the work tool.  
   
   
       18 . A hydraulic hammer according to  claim 15 , wherein the engaging structure includes mutually engaging protrusions on the upper and lower housing members.  
   
   
       19 . A hydraulic hammer according to  claim 15 , wherein the engaging structure includes a bayonet coupling  
   
   
       20 . A method of assembling a tool assembly, comprising: 
 providing a lower housing member defining a lower chamber,    providing an upper housing member defining a upper chamber,    providing a work tool housed in one of the lower and upper chambers,    engaging the lower housing member and the upper housing member by relative rotation of the upper and lower housing members to form a tool assembly defining a single chamber comprising the lower and upper chambers, and    applying a prestressing force to urge the lower housing member away from the upper housing member.