Wirelaying Apparatus and Wirelaying Method For Electrofusion Welding

Abstract

A wirelaying apparatus ( 2 ) includes a tool arm ( 21 ) with a tool head ( 22 ) which carries a wirelaying tool ( 30 ). The tool ( 30 ) has a cutting tip ( 31 ) through which a wire ( 12 ) is laid into a working surface ( 11 ) of a workpiece ( 10 ). The workpiece ( 10 ) is retained in a retainer ( 40 ) and is moved relative to the wirelaying tool ( 30 ). In use, the cutting tip ( 31 ) follows along an arcuate path while laying the ( 10 ) wire into the working surface ( 11 ) of the workpiece ( 10 ). Thus, more complex wirelaying configurations are achieved, such as a bi-helical wirelaying pattern in a generally cylindrical pipe fitting or a bi-spiral wirelaying pattern in a semi-cylindrical saddle coupler pipe fitting.

1 . A wirelaying apparatus for laying a wire into a working surface of a workpiece, the apparatus comprising:
 a retainer for retaining the workpiece;   a wirelaying tool having a cutting tip for, in use, making a cut into the working surface of the workpiece in response to relative movement of the wirelaying tool with respect to the retainer, wherein the wirelaying tool comprises an aperture for delivering a wire through the cutting tip directly into the cut in the working surface; and   a tool head arranged to carry the wirelaying tool mounted thereon and to move the wirelaying tool relative to the retainer, wherein the tool head is arranged to move the wirelaying tool to, in use, make the cutting tip follow along an arcuate path while laying the wire into the working surface of the workpiece.   
     
     
         2 . The wirelaying apparatus of  claim 1 , wherein the tool head is arranged to move the cutting tip of the wirelaying tool about a centre of rotation such that the cutting tip is offset on a tangential line from the centre of rotation to move along the arcuate path. 
     
     
         3 . The wirelaying apparatus of  claim 1 , wherein the retainer is arranged to move on a linear Z axis with respect to the tool head and to rotate the workpiece about a rotational A axis substantially normal to the linear Z axis. 
     
     
         4 . The wirelaying apparatus of  claim 1 , wherein the tool head is arranged to move on orthogonal X and Y linear axes with respect to the retainer and to rotate the tool head about a rotational C axis substantially normal to a plane of the X and Y linear axes. 
     
     
         5 . The wirelaying apparatus of  claim 1 , further comprising a wirelaying station including a tool arm to carry and move the tool head, a milling station including a milling cutter, and the retainer arranged to move in use between the wirelaying station and the milling station while retaining the workpiece. 
     
     
         6 . The wirelaying apparatus of  claim 1 , wherein the tool head is arranged to move the wirelaying tool to form a bi-spiral pattern in the working surface of the workpiece by moving the wirelaying tool in an arc of decreasing radius about a notional centre point to form a first spiral pattern, moving the wirelaying tool in an arc of substantially constant radius about a centre of rotation to form a turnaround, and moving the wirelaying tool in an arc of increasing radius about the notional centre point to form a second spiral pattern interleaved with the first spiral pattern. 
     
     
         7 . The wirelaying apparatus of  claim 1 , wherein the workpiece is a saddle coupler pipe fitting having a semi-cylindrical working surface. 
     
     
         8 . The wirelaying apparatus of  claim 1 , wherein the tool head further comprises a rotating tool holder arranged to rotate the wirelaying tool with respect to the tool head. 
     
     
         9 . The wirelaying apparatus of  claim 8 , wherein:
 the workpiece is a hollow cylinder and the working surface is an interior bore surface of the hollow cylinder;   a support arm is arranged to cause a relative linear movement and a relative rotation of the tool head with respect to the retainer, such that in use the tool head is arranged to enter into the hollow cylinder during relative rotation of the hollow cylinder with respect to a longitudinal axis thereof;   the tool head is carried at one end of the support arm;   the wirelaying tool is detachably mounted to the tool head, and the cutting tip is arranged to form a cut into the interior bore surface of the hollow cylinder in response to said relative linear movement and said relative rotation; and   the rotating tool holder is arranged to rotate the wirelaying tool with respect to the tool head about a centre of rotation such that the cutting tip describes an arc about the centre of rotation while laying the wire into the interior bore surface of the hollow cylinder.   
     
     
         10 . The wirelaying apparatus of  claim 9 , wherein:
 the support arm is arranged to perform a first relative rotation and a first relative linear movement with respect to the retainer, thereby laying the wire into the interior bore surface along a first helical path from a starting point to a turnaround point;   the rotatable tool holder is arranged to rotate the wirelaying tool along an arcuate path through an angle of substantially 180°, thus laying the wire in an arc at the turnaround point; and   the support arm is arranged to perform a second relative rotation and a second relative linear movement with respect to the retainer, thereby laying the wire along a second helical path from the turn-around point back towards the starting point, wherein the second helical path is interleaved with the first helical path to form a double helical coil.   
     
     
         11 . The wirelaying apparatus of  claim 1 , wherein the wirelaying tool comprises a body and the cutting tip projects from the body for making the cut into the working surface of the workpiece. 
     
     
         12 . The wirelaying apparatus of  claim 11 , wherein the wirelaying tool further comprises a flap closer for closing the cut thereby enclosing the wire in the cut, and the cutting tip, the body, and the flap closer are integrally formed. 
     
     
         13 . A method for laying wire into a working surface of a workpiece, comprising the steps of:
 forming a first wirelaying pattern by opening a cut with a cutting tip of a wirelaying tool into the working surface of the workpiece by relative movement of the workpiece with respect to the wirelaying tool, feeding the wire into the cut through the cutting tip of the wirelaying tool, and closing the cut thereby enclosing the wire in the cut;   rotating the wirelaying tool with respect to the workpiece such that a cutting direction of the wirelaying tool is changed while continuously laying wire into the working surface, wherein the cutting tip rotates along an arcuate path around a centre of rotation while laying the wire into the working surface; and   forming a second wirelaying pattern by a further relative movement of the workpiece with respect to the wirelaying tool.   
     
     
         14 . The method of  claim 13 , wherein the second wirelaying pattern is interleaved with the first wirelaying pattern and the change of direction reverses the cutting direction of the wirelaying tool. 
     
     
         15 . The method of  claim 13 , for forming a bi-spiral wirelaying pattern, such as in a saddle coupler workpiece, wherein:
 the step of forming a first wirelaying pattern includes moving the wirelaying tool in an arc of decreasing radius about a notional centre point to form a first spiral pattern;   the rotating step includes moving the wirelaying tool in an arc of substantially constant radius about a centre of rotation to form a turnaround; and   the step of forming a second wirelaying pattern includes moving the wirelaying tool in an arc of increasing radius about the notional centre point to form a second spiral pattern interleaved with the first spiral pattern.   
     
     
         16 . (canceled) 
     
     
         17 . (canceled)