MULTIPLE UPSET, COLD PRESSURE, WELDING APPARATUS

Abstract: Multiple upset, cold pressure, welding apparatus including (Fig. 2) a welding die set having two pairs of die halves (2) each formed with a longitudinal groove (4) in a split line face (8) providing a bore for effecting gripping of end portions (12) of first and second workpieces and reciprocable between the closed position in which the associated portion of the workpiece is gripped and an open position in which the associated portion of the workpiece is released and also being reciprocable in a direction parallel to the longitudinal axis of the workpiece to apply or relax a welding pressure across abutting faces of the end portions of the workpieces, each die being formed with a longitudinal groove (4) having outwardly diverging flanks terminating in a linear knife edge (6) bounding a recess (10) extending longitudinally parallel to the groove (4) in the split line face (8) of the die. Since, during clamping of the workpiece, any excess material deforms as flash (14), workpieces with end portions (12) of over-size or mis-shapen form may be clamped within the groove (4) without inhibiting the clamping effect or producing an unacceptable bursting force on the die halves. A satisfactory clamping effect is obtained over a larger tolerance band of workpiece dimensions than hitherto, thereby enhancing the versatility of a set of dies in respect of the range of workpieces which may be accommodated.

Description: TITLE: MULTIPLE UPSET, COLD PRESSURE, WELDING APPARATUS DESCRIPTION This invention relates to multiple upset, cold pressure, welding apparatus for effective butt welds in wire, rod, strip or tubular workpieces. WO 96/39272 describes a multiple upset, cold pressure, welding apparatus including a welding die set having two pairs of die halves each formed with a longitudinal groove in a split line face providing a bore in a closed position of the respective pairs of die halves for effecting gripping of end portions of first and second workpieces reciprocable between the closed position in which the associated portion of the workpiece is gripped and an open position in which the associated portion of the workpiece is released and also being reciprocable in a direction parallel to the longitudinal axis of the workpieces to apply or relax a welding pressure across abutting faces of the end portions of the workpieces. According to the present invention, each die is formed with a split line face having a longitudinal groove generally corresponding in contour to a half section of the workpiece and having outwardly diverging flanks, each flank terminating in a linear knife edge bounding a recess extending longitudinally parallel to the groove in the split line face of the die. In one embodiment of the invention, as shown in Figures 1 , 2 and 3, a pair of die halves 2 are formed with grooves 4 of part circular cross-section having knife shear edges 6 displaced from a plane containing die split line faces 8 of the respective halves 2. Recesses 10 are provided outwardly of the knife shear edges 6, and extend over the length of the die half parallel to the groove 4. In operation, end portions 12 of first and second workpieces are fed to respective pairs of die halves 2 and a clamping force applied to urge associated halves towards each other to a position as shown in figure 2 with the split line faces 8 abutting. The end portions 12 are clamped within the grooves 4 and any excess material arising from the end portion 12 being oversize in relation to the groove 4 deforms as flash 14 into the recess 10. The pairs of die halves 2 are then urged toward each other to initiate a cold pressure welding operation. Since any excess material deforms as flash 14, workpieces with end portions 12 of over-size or mis-shapen form may be clamped within the grooves 4 without inhibiting the clamping effect or producing an unacceptable bursting force on the die halves. As a result, a satisfactory clamping effect is obtained over a tolerance band of workpiece dimensions larger than has hitherto been attainable, thereby enhancing the versatility of a set of dies in respect of the range of workpieces which may be accommodated. In another embodiment, not shown, the knife shear edges 6 are arranged to lie in the plane of the split line faces 8 such that, upon effecting clamping, the knife shear edges 6 sever the flash which is then removed upon the die halves 2 moving apart. It will be appreciated that the recesses 10 may have cross-sections other than that depicted in Figures 1 and 2, such as, for example, semi-circular.

Claims: Claims 1. Multiple upset, cold pressure, welding apparatus including a welding die set having two pairs of die halves (2) each formed with a longitudinal groove (4) in a split line face (8) providing a bore in a closed position of the respective pairs of die halves for effecting gripping of end portions (12) of first and second workpieces reciprocable between the closed position in which the associated portion of the workpiece is gripped and an open position in which the associated portion of the workpiece is released and also being reciprocable in a direction parallel to the longitudinal axis of the workpiece to apply or relax a welding pressure across abutting faces of the end portions of the workpieces, chacterised in that each die is formed with a split line face (8) having a longitudinal groove (4) generally corresponding in contour to a half section of the workpiece (12) and having outwardly diverging flanks, each flank terminating in a linear knife edge (6) bounding a recess (10) extending longitudinally parallel to the groove (4) in the split line face (8) of the die. 2. Multiple upset, cold pressure, welding apparatus as claimed in Claim 1, characterised in that the knife shear edges (6) lie in a plane containing the split line faces (8).

Inventors: BEECHING MARK ADRIAN, BEECHING, MARK, ADRIAN
Applicants: BEECHING MARK ADRIAN, BWE LTD, BEECHING, MARK, ADRIAN, BWE LIMITED
Application year: 2000
Main classification: B23K20
IPC codes: B23K20