JP2009208120A - Manufacturing method of electric resistance welded tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electric resistance welded tube by which an end of a workpiece can be prevented from being fused. <P>SOLUTION: In the manufacturing method of an electric resistance welded tube 11, the workpiece 2 is formed which is machined by bending a planar steel plate 1 into a tubular shape, and then both edges 4, 5 are welded to each other from the outside in the axial direction and joined. Shield members 6, 7 having deposition resistance are joined flush with both edges 4, 5 of the ends 2a, 2b of the workpiece 2, so that the welding is performed in a manner straddling over the shield members 6, 7 and both edges 4, 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an electric resistance welded tube.

2. Description of the Related Art Conventionally, a technique of manufacturing an electric resistance welded tube in which a flat steel plate is bent into a tubular shape and a work member is formed and both edges thereof are welded to each other is known (patent) References 1 and 2).
JP 2000-301232 A JP 09-2160942 A

However, in the conventional invention, when the welding start position or end position of the workpiece member is set at the end portion, there is a problem that large thermal stress due to welding is concentrated on the end portion and deformation or the like is likely to occur. It was.
Furthermore, since the welding joint strength is low, there is a possibility that deformation or the like may occur in the weld bead when the welded ERW pipe is subjected to plastic deformation by reducing or expanding the diameter.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing an electric resistance welded tube that can prevent fusing of an end portion of a work member.

  In the invention of claim 1 of the present invention, a work member formed by bending a flat steel plate into a tubular shape is formed, and both edges thereof are welded and joined from the outside over the axial direction. In the method for manufacturing an electric resistance welded tube, a shield member having welding resistance is connected to both edges of the end of the work member, and the welding is performed across the shield member and both edges.

In the invention according to claim 1, since a shield member having welding resistance is connected to both edges of the end portion of the work member and welding is performed across the shield member and both edges, a large thermal stress due to welding is generated. There is no fear of concentrating on the end portion, thereby preventing deformation and the like.
Further, since the shield member has weld resistance, there is no possibility that the shield member and the work member are welded.

  Embodiments of the present invention will be described below with reference to the drawings.

Example 1 will be described below.
1 and 2 are views for explaining the formation of the work member of the first embodiment, FIG. 3 is a plan view for explaining the welding apparatus of the first embodiment, and FIG. 4 is a cross-sectional view (partial cross-section) taken along line S4-S4 of FIG. Is omitted).
FIG. 5 is a plan view for explaining the arrangement of the welding apparatus and the work member according to the first embodiment, FIGS. 6 to 8 are diagrams for explaining welding of both edges of the work member according to the first embodiment, and FIG. It is a top view which shows an electric sewing tube.

First, an apparatus for manufacturing an electric resistance welded tube of Example 1 will be described.
In the method for manufacturing the electric resistance welded tube of Example 1, the pre-process S1 and the post-process S2 are performed in this order.

<Pre-process>
First, in the pre-process S1, the flat steel plate 1 as shown in FIG. 1 is bent into a tubular shape using a known roll forming apparatus (not shown) to form a work member 2 as shown in FIG.

<Post process>
Next, in post-process S2, both edge parts 4 and 5 (refer FIG. 2) of the workpiece member 2 are joined using the welding apparatus 3 shown to FIG.
Specifically, the welding apparatus 3 according to the first embodiment includes a pair of shield members 6 and 7, a shrink mold 8, a welding torch 9, and the like that are arranged to face each other at a predetermined interval.

The shield member 6 is formed in a substantially cylindrical shape having a step portion 6c between a tip portion 6a and a base end portion 6b having different diameters, and the base end portion 6b is a drive device (such as a hydraulic cylinder) not shown. The rod 6d is connected to the rod 6d and is movable in the axial direction (arrow direction in the figure) by expansion and contraction of the rod 6d.
The shield member 6 is made of a copper-based or silver-based alloy, and has excellent characteristics such as welding resistance and arc resistance (welding resistance of claims), wear resistance, high conductivity, and low contact resistance. ing.

  The shield member 7 is made of the same material as the shield member 6 and is formed in a substantially cylindrical shape having a step portion 7c between a distal end portion 7a and a proximal end portion 7b having different diameters, and the proximal end portion 7b is not shown. It is connected to a rod 7d of a drive device (hydraulic cylinder or the like), and is provided so as to be movable in the axial direction (arrow direction in the figure) by expansion and contraction of the rod 7d.

The shrink mold 8 is disposed so as to surround the periphery of the shield member 7, and further includes a pressing surface having a gap corresponding to the plate thickness of the work member 2 between the outer periphery of the shield member 7 and the axial direction. A substantially cylindrical pressing roller 8a that is rotatable is provided on both sides and below the shield member 7, respectively.
In addition, an opening 8b is cut out on the shield member 6 side above the shrink mold 8, and a welding torch 9 is placed on the upper side while facing the base end side of the opening 8b. Has been placed.
In addition, a blade-like regulating member 10 is disposed in a state of facing the opening 8b adjacent to the welding torch 9.
Further, the inner diameter L1 of the through hole 8c of the shrink mold 8 is formed to be slightly inclined so as to be larger than the outer diameter of an electric sewing tube 11 to be manufactured, which will be described later, and become narrower toward the shield member 6 side. On the other hand, the center-to-center dimension L2 between the rotating rollers 8a arranged on both sides of the shield member 6 is set to coincide with the outer diameter of the electric sewing tube 11 to be manufactured, which will be described later.

  The welding torch 9 is a welding torch of a known plasma welding machine and performs welding by melting and resolidifying a material to be welded with high-temperature energy by a plasma arc.

  In order to join both edge portions 4 and 5 of the workpiece member 2 using such a welding apparatus 3, first, as shown in FIG. 5, the edge portions 4 and 5 of the workpiece member 2 are connected to the welding torch 9 side. The tip portions 6a and 7a of the corresponding shield members 6 and 7 are inserted inside the both end portions 2a and 2b, respectively, and connected in a flush state.

At this time, the tip 7 a of the shield member 7 is fitted inside the end 2 b of the work member 2, the rod 7 d of the shield member 7 is extended, and the work member 2 is pushed into the center hole 8 c of the shrink mold 8. Thus, the end 2 a of the work member 2 is fitted to the tip 6 a of the shield member 6.
At this time, both end portions 2a and 2b of the work member 2 can be positioned by contacting the corresponding step portions 6c and 7c, respectively.

Further, the one end 2a side of the work member 2 is in contact with the inclined center hole 8c of the shrink mold 8 so that both edge portions 4 and 5 are close to each other, while both edges on the other end 2b side are in contact with each other. A very small gap L3 is formed between the portions 4 and 5, and the sword-shaped tip of the regulating member 10 is inserted and arranged by a driving device (not shown).
Further, a base end portion 6 b of the shield member 6 is disposed immediately below the welding torch 9, whereby a predetermined distance L 4 is provided between the one end portion 2 a of the work member 2 and the welding start position of the welding torch 9. Will be provided.

  Next, the rods 6d and 7d of the shield members 6 and 7 are driven synchronously to move the work member 2 in the direction of the arrow in FIG. 5 and the plasma arc 9a is shown by the welding torch 9 (shown by the dashed line in FIG. 6). , The two edges 4 and 5 of the work member 2 are welded and joined in the axial direction.

At this time, as shown in FIG. 6, the work member 2 is supported by the lower pressing roller 8a and is pressed and sandwiched between the pressing rollers 8a on both sides, thereby bringing the two edges 4 and 5 into close contact with each other. Welding can be performed.
Further, the regulating member 10 can be inserted into the gap L3 to prevent the circumferential displacement of the workpiece member 2 being welded.

Further, as shown in FIG. 7, at the start of welding, the welding torch 9 radiates a plasma arc 9a from the base end portion 6b of the shield member 6 to both edges 4 and 5 of the one end portion 2a of the work member 2. To do.
Thereby, since the welding start position where the thermal stress by welding is large is the base end portion 6b of the shield member 6, it is possible to prevent deformation of both edge portions 4 and 5 of the end portion 2a of the work member 2.
Further, since the shield member 6 has weld resistance, the weld bead X1 (see FIG. 9) is formed only on both edges 4 and 5 of the work member 2, and at the same time, the shield member 6 and the work member 2 are welded. It never happens.

Further, as shown in FIG. 8, at the end of welding, the welding torch 9 causes the plasma arc 9 a to extend from both edges 4 and 5 of the other end 2 b of the work member 2 to the base end 7 b of the shield member 7. Radiate.
Thereby, since the welding end position where the thermal stress due to welding is large becomes the base end portion 7b of the shield member 7, it is possible to prevent deformation of both edge portions 4 and 5 of the other end portion 2b of the work member 2.
Further, since the shield member 7 has weld resistance, the weld bead X1 is formed only on both edge portions 4 and 5 of the work member 2, and at the same time, the shield member 7 and the work member 2 are not welded.

  Further, since the front end portions 6a and 7a of the shield members 6 and 7 are overlapped inside the both end portions 2a and 2b of the work member 2, it becomes difficult to form a back bead inside the both end portions 2a and 2b.

Finally, by removing the work member 2 from the welding device 3, a desired electric resistance welded tube 11 as shown in FIG. 9 is obtained.
In addition, the use of the electric sewing tube 11 can be set as appropriate, and is suitable for use in a tubular body having a sealing property such as an exhaust pipe.
Further, the electric resistance welded tube 11 is excellent in the joining strength of the both edges 4 and 5 by good welding, and in particular, even if the electric resistance welded tube 11 is reduced in diameter or expanded and plastically deformed, a crack may occur in the weld bead X1. Not suitable.

Next, the effect will be described.
As described above, in the method of manufacturing the ERW tube 11 of the first embodiment, the work member 2 is formed by bending the flat steel plate 1 into a tubular shape, and both edge portions 4 and 5 thereof are formed. In the manufacturing method of the electric resistance welded tube 11 which is welded and joined to each other from the outside in the axial direction, the shield member having resistance to welding at both edges 4 and 5 of the end portions 2a and 2b of the work member 2 6 and 7 are connected and welding is performed across the shield members 6 and 7 and both edge portions 4 and 5, so that fusing of the end portions 2 a and 2 b of the work member 2 can be prevented.
Further, since the shield members 6 and 7 have weld resistance, there is no possibility that the shield members 6 and 7 and the workpiece member 2 are welded.

Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and design changes and the like within the scope not departing from the gist of the present invention are included in the present invention.
For example, the detailed configuration of the welding apparatus 3 can be set as appropriate. For example, in the first embodiment, the welding torch 9, the shrink mold 8, and the regulating member 10 are set as the fixed side, and the work member 2 is set as the moving side. It only needs to move relative.

Further, in Example 1, the pre-process and the post-process were separated, but they may be performed continuously. In this case, an electric resistance welded tube is continuously formed while a strip-shaped steel sheet is pulled out from the uncoiler, and a predetermined length is obtained. The work member is provided with a shield member at the start or end of uncoiler drawing.
Furthermore, in the first embodiment, the shield members 6 and 7 are integrally formed. However, only the portion that is hit by the plasma arc 9a may be formed of a material having non-weldability.

It is a figure explaining formation of the work member of Example 1. FIG. It is a figure explaining formation of the work member of Example 1. FIG. It is a top view explaining the welding apparatus of Example 1. FIG. It is sectional drawing in the S4-S4 line | wire of FIG. 3 (a partial cross section is abbreviate | omitted). It is a top view explaining arrangement | positioning of the welding apparatus and work member of Example 1. FIG. It is a figure explaining welding of the both edge parts of the workpiece | work member of Example 1. FIG. It is a figure explaining welding of the both edge parts of the workpiece | work member of Example 1. FIG. It is a figure explaining welding of the both edge parts of the workpiece | work member of Example 1. FIG. 1 is a plan view showing an electric resistance welded tube of Example 1.

Explanation of symbols

X1 welding bead 1 steel plate 2 work member 3 welding device 4, 5 both edges 6, 7 shield members 6a, 7a tip 6b, 7b base 6c, 7c step 6d, 7d rod 8 shrink type 8a pressure roller 8b opening Part 8c Center hole 9 Welding torch 9a Plasma arc 10 Restricting member 11 ERW

Claims (1)

In the manufacturing method of the electric resistance welded tube, which is formed by bending a flat steel plate into a tubular shape and forming a work member and welding both edges thereof from the outside over the axial direction.
A method of manufacturing an electric resistance welded tube, comprising: connecting a shield member having weld resistance to both edges of the end portion of the work member; and performing the welding across the shield member and both edges.

Images