JPS60111728A - Expanding method of electric welded pipe - Google Patents

Abstract

PURPOSE:To true up an expanded pipe-end and to eliminate labor required for forming by fitly inserting an expanded pipe end-edge into the groove of buckling punch of a punch base-part and pushing back the end-edge to buckle the projection of a welded-line part, in expanding an electric welded pipe by using an expanding punch. CONSTITUTION:In case of expanding a pipe by forcing an expanding punch 2 into an electric welded pipe 11; the pipe end is trued up by pushing back the end- edge 13 of expanded pipe, fitly inserted into the groove 7 of a buckling punch 5, and buckling the projection produced by the insufficient stretching due to the work-hardening of a welding-line part. Thus the operation man-hour is reduced by eliminating labor required usually for touching up the end-edge of expanded pipe, and the operating efficiency is improved.

Description

[Detailed description of the invention] The purpose of the method of the present invention is to rationally eliminate unavoidable defects in the expansion work of electric resistance welded pipes, such as mesh pipes, by one action of the pipe expansion work. Electric resistance welded pipes are often used as fluid pipes after being coated with anti-corrosion plating. Since the weld line is heated and hardened during sewing, the stretchability is not uniform. For this reason, when a tube expansion tool is press-fitted from the end edge C of the welded pipe a as shown in FIG. 1, a protruding portion d is produced at the end edge C due to poor extensibility of the weld line 1). This is because the metal material other than the weld line is stretched and expanded while shrinking in the axial direction, but the weld line has poor stretchability and therefore almost no axial shrinkage occurs. It does not actively cause protrusion. However, there is no difference in the fact that the tube expansion causes the lily to become defective. For this reason, after the pipe expansion work, the projecting portion d is cut off by turning it on a lathe or by applying a machining process, as shown in Fig. 2, and the end edge portion C is finished to be aligned. The method of the present invention eliminates the need for such finishing.

Examples of the method of the present invention will be described.

Pit 3MIf Pipe expansion bunch 1 used in the method of the present invention
This shows the ERW IF! A conical guide 3 is formed at the tip of an inner rod-shaped material 2 having an outer diameter larger than the inner diameter of the ERW tube 11, and the tube expansion length is determined based on a portion of the conical guide 3 that corresponds to the inner diameter of the ERW tube 11 before expansion. The buckling bunch 5 is fitted and fixed so as to match the length L. The buckling punch 5 is provided with a protruding ring portion 6 that forms a ring-shaped slit 7 approximately matching the thickness of the electric resistance welded tube 11 between the outer periphery of the inner bar-shaped material 2 and the outer circumference of the inner rod-shaped material 2. Reference numeral 4 denotes a relief annular groove with a concave arc cross section formed on the inner bar-shaped material 2 on the front side of the buckling bunch 5, and is used when the inner surface of the electric resistance welded pipe 11 is plated with soft metal. This is a depression for adhering plated metal, welding layer, etc. that are cut by the tube expansion punch 1, and for occasionally wiping it off.

8 is a punch holder into which the rear side of the buckling bunch 5 of the inner rod-shaped material 2 is fitted.

FIG. 5 shows an outline of the tube expansion device, which includes a pair of clamps 1.6a and 6b for the electric resistance welded tube 11 that can be opened and closed freely, a product stopper 17, and a press stopper against which the punch holder 8 is abutted during the forming operation. It has 18 mag.

To explain the method of the present invention with reference to FIG. 3.4, when the tube expansion punch 1 is press-fitted as usual through the opening of the end edge 13 on one side of the electric resistance welded tube 11 clamped by the clamps i6a and 16b, as shown in FIG. As described above, while a protrusion grows at the weld line 12 of the edge 13, it moves toward the buckling bunch 5 on the outer periphery of the punch 1, enters the ring-shaped slit 7, and forms the seat. When the state punch 5 hits, the protruding portion is pushed back, causing the protruding portion and its vicinity to contract in the length direction and buckle (see FIG. 4).

Therefore, a well-organized expanded tube product as shown in FIG. 2 can be obtained without cutting off the protruding portion of the expanded rear end edge 13.

The method of the present invention performs a tube expansion operation near one end of an ERW tube using the (r)
It has an excellent effect of easily removing defects in tube forming.

[Brief explanation of the drawing]

Fig. 1 is a perspective view illustrating defects that occur during the expansion of ERW pipes, Fig. 2 is a perspective view of the finished product after finishing, and Fig. 3.
FIG. 4 is a side view of the method of the present invention, with FIG. 3 showing the state before the pipe expansion work and FIG. 4 showing the state after the pipe expansion work has been completed. FIG. 5 is a schematic side view of an apparatus for carrying out the method of the invention. 1 → Pipe expansion bunch 5 → Buckling punch 11 → ERW pipe 12 → Welded part 13 → Edge applicant Horie Metal Industry Co., Ltd. Commissioner of the Patent Office 1. Description of the case Japanese Patent Application No. 58-218346 2, title of the invention Method for expanding ERW pipes 3, person making the amendment Relationship to the case Applicant Address 2-26 Hatonosu-cho, Toyota City Name Soseki Metal Industry Co., Ltd. 4, Agent February 8, 1982

Claims (1)

[Claims] 7! In this method, a tube expansion punch is press-fitted from the tube end of the im tube to expand the tube; A buckling punch is provided to relatively push back the weld line part 1, and while the part outside the weld line part 1 of the ERW pipe is contracted in the axial direction, the weld line part is hardened due to welding. 1 and ¥ based on the remaining stretching defects that caused it! Ar
A method for expanding an electric resistance welded pipe, characterized in that the protruding portion is pushed back using the buckling punch described in item t, thereby aligning the tube end of the weld line portion with the weld line portion other than the weld line portion.