Method and system for forming a recess in a tubular workpiece

Abstract

A roller support block 10 supports rolling rollers ( 6˜9 ) in four stages and moves in a guide hole ( 13 ) of a pipe holder ( 5 ) to sequentially bring the rolling roller into pressure contact with a pipe ( 2 ) held immovable by the pipe holder ( 5 ) through an aperture ( 35 ) made in the pipe holder ( 5 ). In this process, the first-stage rolling roller ( 6 ) first comes into rolling pressure contact with the pipe for preliminary shaping of a recess. Subsequently, the second-stage and third-stage rolling rollers ( 7, 8 ) advance the preliminary shaping to enlarge and deepen the recess. Finally, the fourth-stage rolling roller 9 finally shapes the recess to a first locking groove ( 3 or 4 ).

1 . A method of forming a recess in a tubular workpiece comprising: 
 preparing a set of rolling rollers in multiple stages capable of sequentially interfering the workpiece in an intersecting direction;    having the rolling rollers sequentially get into pressure contact with the workpiece by relative movement between the rolling rollers and the workpiece to bring about preliminary shaping and final shaping and thereby form the recess in the workpiece; and    preparing a workpiece holder capable of holding the workpiece immovable by enveloping the workpiece and having an aperture through which the rolling rollers can sequentially interfere with the workpiece,    wherein the rolling rollers get into pressure contact with the workpiece through the aperture.    
   
   
       2 . The method according to  claim 1  wherein the final-stage rolling roller among the set of rolling rollers, which finally comes into pressure contact with the workpiece, makes substantially no gap between side edges thereof and opposed edges of the aperture, and thereby forms the recess with a sharp engagement surface.  
   
   
       3 . The method according to  claim 2  wherein the contour of the recess is substantially equal to the contour of the aperture.  
   
   
       4 . The method according to  claim 1  wherein the multi-step rolling rollers are freely rotatable.  
   
   
       5 . The method according to  claim 4  wherein diameters of the multistage rolling roller are smaller the four times the diameter of the workpiece.  
   
   
       6 . The method according to  claim 1  further comprising: 
 preparing plural sets of the rolling rollers in multiple stages, and using them simultaneously to a plurality of said recesses simultaneously.    
   
   
       7 . A method of forming a recess in a tubular workpiece, comprising: 
 preparing a workpiece holder having an aperture through which the rolling rollers can sequentially interfere with the workpiece and capable of holding the workpiece immovably by enveloping the circumference thereof, and a set of rolling rollers in multiple stages capable of getting in pressure contact with the workpiece through the aperture; and    having the rolling rollers sequentially get into pressure contact with the workpiece through the aperture to bring about preliminary shaping and final shaping and thereby form the recess in the workpiece.    
   
   
       8 . The method according to  claim 7  wherein all of the rolling rollers in multiple stages are identical in diameter, and center axes of the rolling rollers in different stages are sequentially offset in the direction perpendicular to the lengthwise axis of the workpiece held in the workpiece holder.  
   
   
       9 . The method according to  claim 7  wherein the rolling rollers in different stages vary in diameter sequentially in one direction, and center axes of all rolling rollers in multiple stages lie on a straight line parallel to the lengthwise axis of the workpiece held in the workpiece holder.  
   
   
       10 . A system for forming a recess in a tubular workpiece comprising: 
 a roller support block that holds a set of rolling rollers in multiple stages aligned in a row and permits the individual rolling rollers to rotate; and    a workpiece holder having a workpiece-receiving hole substantially equal in cross-sectional configuration to the workpiece and capable of holding the workpiece immovably in the workpiece-receiving hole, said workpiece holder having an aperture exposing a part of the workpiece held in the workpiece-receiving hole,    wherein the rolling rollers sequentially come into pressure contact with the workpiece through the aperture along with relative movement between the roller-receiving block and the workpiece holder, and thereby performing preliminary shaping and final shaping sequentially to form the recess in the workpiece.    
   
   
       11 . The system according to  claim 10  wherein plural sets of rolling rollers in multiple stages are provided.  
   
   
       12 . The system according to  claim 10  wherein one of the rolling rollers in the final stage in each set makes substantially no gap between a side edge of the outer circumferential portion thereof and the contour of the aperture, and can make a sharp engagement surface having an angled edge in the recess in the workpiece in alignment with the contour of the aperture.  
   
   
       13 . A system for forming a recess in a tubular workpiece comprising: 
 a roller support block that holds a set of rolling rollers in multiple stages vertically aligned in a row and permits the individual rolling rollers to rotate;    a guide member having a guide hole for guiding vertical movements of the roller support block;    a hydraulic cylinder vertically driving the roller support block under the guide by the guide hole; and    a workpiece holder located horizontally adjacent to the guide member and having a workpiece-receiving hole having a contour substantially identical to the cross-sectional configuration of the workpiece at least in a portion thereof for supporting a portion of the workpiece to be processed to form a recess therein, said workpiece holder being capable of holding the workpiece immovably in the workpiece-receiving hole,    wherein said workpiece holder having an aperture through which the rolling rollers can sequentially interfere with the workpiece held immovably in the workpiece-receiving hole to permit the rolling rollers in multiple stages to come into pressure contact with the workpiece and thereby perform preliminary shaping and final shaping sequentially to form the recess in the workpiece.    
   
   
       14 . The system according to  claim 13  wherein the roller support block supports horizontally aligned plural sets of the rolling rollers in multiple vertical stages.  
   
   
       15 . The system according to  claim 13  wherein the aperture has a contour substantially equal to the contour of the recess formed in the workpiece.  
   
   
       16 . The system according to  claim 13  wherein one of the rolling rollers in the final stage makes substantially no gap between a side edge of the outer circumferential portion thereof and a side edge of the aperture, and can make a sharp engagement surface having an angled edge in the recess in the workpiece in alignment with said side edge of the aperture.  
   
   
       17 . The system according to  claim 13  wherein the workpiece holder is composed of a lower holder half and a upper holder half both having elongated grooves in form of upper and lower halves of said workpiece-receiving hole, said upper holder half being driven vertically by a second hydraulic cylinder.  
   
   
       18 . The system according to  claim 12  wherein the rolling rollers in multiple stages have the relation of similar figures.  
   
   
       19 . A method of forming a recess in a tubular workpiece held immovably, comprising: 
 preparing a set of rolling rollers identical in diameter and aligned in a row perpendicular to the lengthwise direction of the workpiece; and    having the rolling rollers sequentially roll on and compress the workpiece along with relative movement between the rolling rollers and the workpiece to form a recess at the compressed portion of the workpiece, said recess having a plane perpendicular to the lengthwise direction of the workpiece,    wherein center axes of said rolling roller equal in diameter are gradually offset from an imaginary line parallel to said relative movement so that the amount of depression of the pipe made by sequential compression by the rolling rollers increases gradually.    
   
   
       20 . The method according to  claim 2  wherein the multi-step rolling rollers are freely rotatable.