CONTACT TIP FOR ARC WELDING WITH A CHANNEL HAVING A STELLATE, MULTI-LOBULAR CROSS-SECTION WITH CONVEXLY ROUNDED SIDES

Abstract

The invention relates to a contact tip (1) for arc welding with at least one channel (2) passing through the contact tip (1) for receiving a welding wire (3), the channel (2) having a non-round stellate, multi-lobular cross-section with convexly rounded sides.

Claims

1.-14. (canceled)

15. A contact tip for arc welding, comprising a channel passing through the contact tip for receiving a welding wire and having a cross-section which is non-round and has in cross-section a stellate, multi-lobular profile with convexly rounded sides, said channel having a basic shape in the form of a polygon with at least 3 corners, within which the channel is located, said convexly rounded sides being configured in cross-section at least partially as circular arcs which are defined by a radius, and having a center point located outside the polygon, said convexly rounded sides including a central region which is convexly rounded, and edge regions adjoining the central region tangentially and configured as straight lines, said edge regions being sized each shorter than the central region.

16. The contact tip of claim 15, wherein the multi-lobular profile has an odd number of at least 5 rounded sides.

17. The contact tip of claim 15, wherein the radius of circular arcs is substantially identical within the scope of production tolerances.

18. The contact tip of claim 15, wherein the radius is in a range from 0.5 to 4 mm.

19. The contact tip of claim 15, wherein the rounded sides of the multi-lobular profile define radially innermost points which delimit an inner circle defined by a diameter which is greater by 15 to 20% than a diameter of the welding wire.

20. The contact tip of claim 19, wherein the radius of the circular arcs is greater than a radius of the inner circle.

21. The contact tip of claim 15, wherein pockets, which are rounded in their lowest point, are arranged between adjacent rounded sides of the multi-lobular profile.

22. The, contact tip of claim 15, wherein the contact tip is an extruded profile or a drawing profile.

23. The contact tip of claim 15, wherein the contact tip is made of a cold-drawn material.

24. The contact tip of claim 15, wherein the contact tip is made of copper or a copper alloy.

25. The contact tip of claim 15, wherein the contact tip is made of CuCrZr and has a hardness of 155-190 BHW.

26. The contact tip of claim 15, wherein the contact tip is made of CuCrZr or CuCoBe on an inside and made of a different copper ahoy or of copper on an outside.

Description

[0028] The invention is explained in more detail below with reference to exemplary embodiments shown schematically in the drawings.

[0029] FIG. 1 shows an enlarged view of a cross-section through a contact tip for arc welding;

[0030] FIG. 2 shows an enlarged view of the central channel of FIG. 1 in cross-section;

[0031] FIG. 3 shows a further embodiment of the channel in cross-section;

[0032] FIG. 4 shows a third embodiment of a channel in cross-section and

[0033] FIG. 5 shows a fourth embodiment of a channel in cross-section.

[0034] FIG. 1 shows an enlarged view of a contact tip for arc welding in cross-sectional representation. The contact tip 1 has, on the outside, a cylindrical cross-section and, centrally, a channel 2, passing through in the longitudinal direction of the cylinder, for receiving a welding wire 3. In the invention, the design of the channel 2 is decisive. It is shown greatly enlarged in the following figures.

[0035] FIG. 2 shows that the channel does not have a circular cross-section, but rather the shape of a stellate multi-lobular profile with convexly rounded sides 4. The basic shape of the channel 2 is a pentagonal polygon 5, which is drawn with a dashed auxiliary line. The channel 2 is located inside the polygon 5, and the respectively convexly rounded sides 4 are all identically configured. They are formed by circular arcs which have an approximately identical radius R. The center points M of the respective circular arcs with the radius R are located radially outside the polygon 5. In this exemplary embodiment, the radius R is selected such that the sides 4 meet exactly at a corner point 6 of the polygon 5 or of the channel 2, without cutting beforehand. As a result, an inner circle 7 is defined, which touches the five substantially identically configured sides 4 at innermost points 8 of the sides 4. It has a diameter D1. A welding wire 3 with the smaller diameter is located inside the channel 2. The diameter D1 of the inner circle 7 is approximately 15 to 20% larger than the diameter D2 of the welding wire 3.

[0036] The welding wire 3 lies on the lower two sides 4 in the image plane. A line contact takes place at the contact points K1 and K2. Since the diameter D2 of the welding wire 3 is smaller than the diameter D1 of the inner circle 7, the welding wire 3 can assume different positions, but is always pushed into one of the corners 6.

[0037] Due to the convexly shaped side walls 4, adjacent to each corner 6 there is a pocket 9 which tapers in the shape of a funnel. This pocket $ is relatively deep and makes it possible to absorb wear and dirt. The stellate channel 2 can therefore absorb relatively abundant dirt in its five pockets 9 without the movement of the welding wire 3 being impeded in the longitudinal direction. Production of such pockets 9 by shaping processes is possible in terms of production technology.

[0038] The pockets 9 do not necessarily have to reach up to the outer corner points of the circumscribed polygon 5. FIG. 3 shows an exemplary embodiment in which the radius R of the convex side 4 is selected identically to the exemplary embodiment of FIG. 1. The pockets 9 are not, however, tapered, but are rounded at their lowest points 10 pointing towards the corners 6 of the polygon 5. The volume of the pockets 9 is thereby slightly smaller, but production is simpler. In addition, stress peaks in the very pointed pockets of FIG. 2 are avoided. As a result of the radius R, such a multi-lobular profile also has convexly rounded sides 4. In this embodiment, however, the convex shape is additionally supplemented by straight lines. Each side 4 has a central region 11, which is designed as a circular arc corresponding to the radius R. Approximately identical edge regions 12, 13, which are designed as tangential straight lines, adjoin the central region 11. The edge regions 12, 13 are each shorter than the central region 11, The combination of curved central regions 11 and straight edge regions 12, 13 does not change at the function of the pockets 9. However, the design of the pockets 9 is geometrically simpler. FIG. 3 also shows that the contact points K1, K2 of the welding wire 3 of the sides 4 do not lie in the region of the straight line, but in the respective central region 11, so that the welding wire 3 is positioned in its movement within the channel 2 in exactly the same way as in the exemplary embodiment of FIG. 2.

[0039] FIG. 4 shows a modification of a channel 2, in which the sides 4 are produced with a larger radius R1. The center point M1 is still located further radially outside the polygon 5. The curvature of the sides 4 is thereby less strong. The inner circle 7 is slightly larger, so that the welding wire 3 can be displaced further in the direction of the corners 6 of the stellate polygon 5. Overall, the cross-sectional area of the channel 2 is thus greater. As a result, the pockets 9 are somewhat less deep but wider for this purpose. In absolute terms, the cross-sectional area of a pocket 9 is thereby not smaller, but can be set similarly large, as with a smaller selected radius R of one side 4.

[0040] FIG. 5 shows, analogously to FIG. 3, the exemplary embodiment of FIG. 4 with rounded pockets 9. It can be seen that here too the cross-sectional area of the pockets 9 is reduced only minimally, but the stellate multi-lobular profile has softer contours overall, so that fewer stress peaks are present within the pockets 9, in particular in the region of the deepest 10 of the channel 2 or of the circumscribing polygon 5. Such a channel 2 is easier to produce in particular in the drawing process than channels 2 with very sharp corners 6 and very deep pockets 9. As also in the case of the exemplary embodiment of FIG. 3, nothing changes as a result of the rounding of the tips of the pockets 9 to the contact behavior of the welding wire 3 on the sides 4. It is still guided in line contact over the contact points K1, K2 within the channel 2.

LIST OF REFERENCE NUMERALS

[0041] 1contact tip [0042] 2channel [0043] 3welding wire [0044] 4side [0045] 5polygon [0046] 6corner [0047] 7inner circle [0048] 8innermost point of 4 [0049] 9pocket [0050] 10deepest of 9 [0051] 11central region of 4 [0052] 12edge region of 4 [0053] 13edge region of 4 [0054] D1diameter of 7 [0055] D2diameter of 3 [0056] K1contact point [0057] K2contact point [0058] Mcenter point to R [0059] M1center point to R1 [0060] Rradius [0061] R1radius