GAS METAL ARC WELDING TORCH

Abstract

A welding torch 10 is provided for use in a Gas Metal Arc Welding (GMAW) process. The welding torch 10 includes a torch body 12, a welding tip 16 extending from the torch body 12, and a detachable nozzle 22 which substantially surrounds the welding tip 16 in use to direct gas around the welding tip 16 and onto a workpiece, the nozzle 22 having a front end which faces the workpiece in use and a rear end which attaches to the torch body 12 in use, in which a ring 24 is provided, the ring 24 being substantially axially fixed to the nozzle 22 at the rear end of the nozzle 22, and the ring 24 being rotatable with respect to the nozzle 22, the ring 24 having a screw thread and the torch body having a corresponding screw thread 26, for fixing the nozzle 22 to the torch body 12.

Claims

1. A welding torch for use in a Gas Metal Arc Welding (GMAW) process, the welding torch having a torch body, a welding tip extending from the torch body, and a detachable nozzle which surrounds the welding tip in use to direct gas around the welding tip and onto a workpiece, the nozzle having a front end which faces the workpiece in use and a rear end which attaches to the torch body in use, in which a ring is provided, the ring being axially fixed to the nozzle at the rear end of the nozzle, and the ring being rotatable with respect to the nozzle, the ring having a screw thread and the torch body having a corresponding screw thread, for fixing the nozzle to the torch body.

2. The welding torch as claimed in claim 1, in which the screw threads are single-start screw threads.

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. The welding torch as claimed in claim 1, in which at least a part of the nozzle is made from a non-metallic material, such that a part of the interface between the nozzle and parts inside the nozzle which is exposed to the front end of the nozzle, when the welding torch is assembled, comprises in part the non-metallic material.

10. The welding torch as claimed in claim 9, in which the nozzle is made from metal and in which a non-metallic part of the nozzle is provided in the form of a non-metallic insert.

11. The welding torch as claimed in claim 9, in which the non-metallic material is a thermosetting resin.

12. (canceled)

13. The welding torch as claimed in claim 1, in which the nozzle when fitted to the torch body abuts the torch body or a component fixed to the torch body at an interface, the interface where it is exposed to the open front end of the nozzle forming a continuous curved surface.

14. The welding torch as claimed in claim 13, in which the curved surface is a concave surface which faces the open end of the torch body.

15. A welding torch for a Gas Metal Arc Welding (GMAW) process, the welding torch having: a torch body, a welding tip extending from the torch body, and a detachable nozzle which surrounds the welding tip in use to direct gas around the welding tip and onto a workpiece, the nozzle having a front end which faces the workpiece in use and a rear end which attaches to the torch body in use, in which the nozzle when fitted to the torch body abuts the torch body or a component fixed to the torch body at an interface, and in which at least a part of the nozzle which forms a part of the interface exposed to the open front of the nozzle, is made from a non-metallic material.

16. The welding torch as claimed in claim 15, in which the nozzle abuts a tip adaptor of the welding torch at the point where the interface is exposed.

17. The welding torch as claimed in claim 15, in which the non-metallic material is a thermosetting resin.

18. The welding torch as claimed in claim 17, in which the thermosetting resin is a phenolic resin.

19. The welding torch as claimed in claim 15, in which the non-metallic material is only a part of the nozzle.

20. The welding torch as claimed in claim 19, in which the non-metallic material is provided as an insert to the nozzle.

21. The welding torch as claimed in claim 19, in which the nozzle is made of metal.

22. The welding torch as claimed in claim 21, in which the nozzle comprises copper.

23. The welding torch as claimed in claim 15, in which a ring is provided, the ring being axially fixed to the nozzle at the rear end of the nozzle, and the ring being rotatable with respect to the nozzle, the ring having a screw thread and the torch body having a corresponding screw thread.

24. (canceled)

25. (canceled)

26. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. A welding torch for a Gas Metal Arc Welding (GMAW) process, the welding torch having: a torch body, a welding tip extending from the torch body, and a detachable nozzle which surrounds the welding tip in use to direct gas around the welding tip and onto a workpiece, the nozzle having a front end which faces the workpiece in use and a rear end which attaches to the torch body in use, in which the nozzle when fitted to the torch body abuts the torch body or a component fixed to the torch body at an interface, the interface where it is exposed to the open front of the nozzle forming a continuous curved surface.

32. The welding torch as claimed in claim 31, in which the curved surface is a concave surface which faces the open end of the torch body.

33. The welding torch as claimed in claim 31, in which at least a part of the nozzle which forms a part of the interface exposed to the open front of the nozzle, is made from a non-metallic material.

34. The welding torch as claimed in claim 31, in which the nozzle abuts a tip adaptor of the welding torch at the point where the interface is exposed.

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. (canceled)

44. (canceled)

45. (canceled)

46. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

[0036] FIG. 1 is an exploded view of a welding torch head according to the invention;

[0037] FIG. 2 is a perspective view of a detachable nozzle, part of the welding torch of FIG. 1; and

[0038] FIG. 3 is a cross-section through the nozzle, when fitted to the welding torch head of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] Referring firstly to FIG. 1, a welding torch is indicated generally at 10. The welding torch comprises a torch body 12, a tip adaptor 14 and a contact tip 16 which, when the torch is assembled, extends away from the torch body 12 and is connected to the torch body 12 via the tip adaptor 14.

[0040] FIG. 1 shows a liquid-cooled torch, however the invention is equally applicable to gas-cooled or air-cooled torches.

[0041] Note that for the purposes of this specification, the assembly shown in FIG. 1 is a “welding torch”, sometimes called a “welding torch head”. It is appreciated that in use, hoses, cables and a connection block will be required, and these may be supplied as part of a package with a welding torch.

[0042] A thermal isolator 18 and sealing ring 20, are provided between the tip adaptor 14 and the torch body 12. These components provide for a sealing surface preventing ingress of air around the back of the nozzle, when the welding torch is assembled.

[0043] A nozzle 22 fits over the front end (i.e. the end facing downwards in FIG. 1) of the torch body 12. When the torch 10 is assembled, the nozzle 22 substantially surrounds the contact tip 16 and tip adaptor 14, and guides welding gas—which may be inert or active gas—onto the workpiece.

[0044] A ring 24 is provided, which is assembled to the back end of the nozzle 22 (see FIG. 2). The ring 24 is retained and substantially fixed axially on the nozzle 22, but is free to rotate with respect to the nozzle 22. The ring is internally screw-threaded, and the thread of the ring 24 corresponds with an external screw thread 26 near the front of the torch body 12.

[0045] The ring 24 is retained and substantially fixed axially on the nozzle 22 so that screwing or unscrewing the screw thread of the ring 24 from the screw thread 26 of the torch body 12 will cause the whole of the nozzle 22 to move longitudinally/axially with respect to the torch body 12. It will be understood that there may be a small amount of freedom of axial movement of the ring 24 with respect to the nozzle, but this freedom must be a shorter distance than the axial extent of the screw thread 26. For example there may be a freedom of axial movement of the ring 24 with respect to the nozzle of around 0.5 mm. The amount of axial movement of the nozzle 22 caused by screwing or unscrewing of the thread may be small, for example less than 2 mm or even less than 1 mm, but the thread is designed to deliver a large mechanical advantage in causing this axial movement, and even a small extent of movement is found to be enough to break up accumulated spatter and allow easy release of the nozzle 22 from the torch body 12.

[0046] The thread 26 is a single start thread to provide maximum mechanical advantage so that the ring 24 may be turned relatively easily to provide a large axial force to help remove the nozzle 22 from the torch body 12. In some embodiments, a multi-start thread may be provided, but a single start thread is preferable for maximum mechanical advantage. A single start thread also allows for good mechanical advantage with a relatively coarse thread. A fine thread would give greater mechanical advantage, but may be more vulnerable to damage and more difficult to use, for example when wearing gloves.

[0047] The torch body 12 includes a smooth substantially cylindrical nozzle seating region 25, extending in front of the thread 26. The nozzle 22 includes a corresponding smooth seating region 27, designed to press over the seating region 25 of the nozzle. A number of slots, running down the sides of the nozzle 22 and running parallel to a central axis of the nozzle 22, are provided to facilitate slight radial expansion/compression of the seating region 27 of the nozzle 22. For example, there may be six slots.

[0048] Smooth seating regions and slots for pressing a nozzle onto a welding torch are known in the prior art. However, by adding a threaded ring, not only is a mechanical advantage obtained when removing the nozzle, but centring of the nozzle during fitting is made substantially less difficult and more accurate, resulting in better lamina gas flow and a better weld quality.

[0049] FIG. 3 is a cross-section of the nozzle 22, the contact tip 16, the tip adaptor 14 and part of the torch body 12. The nozzle 22 is made from nickel-plated copper, but includes an insert 28. The insert 28 is made from a phenolic thermosetting resin. The insert 28 takes the form of a sleeve which is permanently fixed inside the nozzle, to form a thickening of the nozzle wall, by crimping. The insert includes an internal flange 29 which extends radially towards the centre of the nozzle, by about 1 mm-2 mm, around the entire internal circumference of the nozzle. The internal flange 29 meets the internal wall of the insert 28, where the internal wall runs parallel to a central axis of the nozzle, at a corner 30 which is a radiused curve. A corresponding corner 32 of the tip adaptor 14 is also a smooth radiused curve, where the tip adaptor broadens outwardly to meet the internal flange 29 of the insert 28. The interface between the insert 28 and the tip adaptor 14 forms a spatter collection chamber, as described in further detail below.

[0050] The radius of each curve is for example about 1.5 mm.

[0051] Where the smooth curved corner 30 of the insert 28 meets the smooth curved corner 32 of the tip adaptor, a concave cavity 34 is defined. The concave cavity 34 is at the only part of the interface between the nozzle 22 and the other parts of the torch 10 which is exposed to weld spatter which potentially enters through the open front end of the nozzle 22. The concave cavity 34 forms a spatter collection chamber. Due to the smooth continuous curved surface of the cavity, as well as the dissimilar materials at the interface, one of which is non-metal, the adherence of weld spatter is substantially reduced. Any weld spatter which does accumulate will tend to form a ring around the tip adaptor 14, in the cavity 34. Any adherence will be primarily to the metallic tip adaptor 14 and not to the plastic insert 28. To remove weld spatter, the nozzle ring 24 can be rotated, which with a great mechanical advantage forces the nozzle 22 slightly forward with respect to the torch body 12. When this is done, the corner 30 of the insert 28 will move forwards with respect to the corner 32 of the tip adaptor 14, and will tend to detach the ring of accumulated weld spatter from the tip adaptor 14, to the extent that it has adhered.

[0052] After forcing the nozzle 22 slightly forward by using the mechanical advantage of the screw thread, and breaking any adhered weld spatter, the nozzle may be twisted and simultaneously pulled forward, removing the nozzle from the torch body and in doing so removing the vast majority of accumulated weld spatter.

[0053] As a result, weld spatter can easily and quickly be removed periodically during a welding job. This increases welder productivity, should result in a higher quality weld, and reduces damage to parts of the welding torch (especially the contact tip and tip adaptor but also the expensive torch body) and thus increases their lifetime and reduces replacement costs.

[0054] FIG. 3 also shows how the thermal isolator 18 and sealing ring 20 provide for a leak-free seal where the closed back end of the nozzle connects to the torch body 12. The thermal isolator is made from a high temperature resin, for example a phenolic resin. The thermal isolator 18 is in the form of a collar which snaps over the back for the tip adaptor 14, and is retained on the back of the tip adaptor by a circumferential ridge running around the tip adaptor 14. The collar has a flange, providing a forward-facing surface (i.e. facing towards the open end of the nozzle when assembled) and a rear-facing surface (i.e. facing towards the torch body 12 when assembled). The forward-facing surface of the thermal isolator 18 abuts a rear-facing surface of the nozzle insert 28. A sealing ring 20 sits behind the rear-facing surface of the thermal isolator 18. The sealing ring 20 is made from a compressible high-temperature engineering plastic, and has a radius slightly greater than the radius of the flange of the thermal isolator 18.

[0055] When assembled. The sealing ring 20 provides a tight seal against the inner wall of the nozzle, forward of the cut-outs of the nozzle. This effectively and completely seals the nozzle, preventing leaks and saving expensive weld gas.

[0056] It will be understood that the description of the embodiments is given by way of example only, and the skilled person will envisage various modifications, improvements and alternatives within the scope of the invention. The invention is set out in the claims.