JPH09136166A - Production of short tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of built-up on the internal circumference face or burr by pressing a circular-arc like contact member to the electrode direction of a welding electrode pressing jig at a butt-welding part of a curved short tube internal circumference and executing butt resistance welding. SOLUTION: A contact member 7 held with a holding tool 8 is brought in contact with a butt end part of the internal circumference of a curved short tube 2. The contact member 7 is a circular-arc like subject, the contact member holding tool 8 having taper pushes the internal circumference face of the curved short tube 2 to the outside of horizontal direction and a pair of opposing contact members 7 are supported. The contact member 7 corrects so that the displacement of the butt end parts of the curved short tube 2 and the gap with the internal circumference faces of welding electrode pressing jigs 5, 6 are eliminated by being pressurized with a cylinder through a taper member 9a and a rod 9b. In such a way, when the electrodes 5a, 6a allow current to flow and butt- welding is executed, built-up to the internal circumference face of the welding part and burr are prevented and. the removing working after welding can be unnecessitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a short pipe which is used as a component of industrial products and which is required to have a relatively thin wall and sufficient strength.

[0002]

2. Description of the Related Art Conventionally, in a method for manufacturing a short pipe by butt resistance welding, in Japanese Patent Publication No. 7-16739, a welding electrode has a semi-arcuate pressing surface only on the outer peripheral surface of a curved short pipe. A pair of welding electrode pressing jigs facing each other is used. However, the swelling of the weld that occurs is crushed or scraped off by an appropriate tool or device.

[0003]

Conventionally, in butt resistance welding, burrs and bulges that occur along the inner and outer peripheral surfaces of the welded portion are unavoidable. In order to remove this and smoothen it, the hardness of this raised part is higher than that of the surrounding unheated part, so the machining efficiency such as cutting of the raised part on the inner peripheral surface is poor, and the processing tool is also high. Steel property is required, and further barrel polishing after cutting is required, which requires a large number of man-hours and costs.

The present invention has been made in view of the above problems, and the present invention is directed to the rise of inner and outer peripheral surfaces generated in a welded portion,
An object of the present invention is to provide a method for manufacturing a short pipe, which prevents swelling to the inner peripheral surface, and reduces man-hours and manufacturing costs such as deburring, cutting, and barrel polishing of the inner peripheral surface.

[0005]

In order to achieve the above object, a pair of opposed welding electrode pressurizing tools having electrically insulating semi-circular pressing surfaces are provided on the outer peripheral surface of a curved short tube. When using the tool to butt resistance weld the end of the butt,
At the abutting end portion of the inner peripheral surface of the curved short pipe, an arc-shaped contact member of an electric insulator having a shape suitable for forming the short pipe,
The present invention provides a method for manufacturing a short pipe in which butt resistance welding is performed while pressing the welding electrode pressing jig in the direction of the electrode.

[0006]

In the butt resistance welding of a curved short pipe, the deviation of the end of the butt, the gap with the welding electrode pressurizing jig, the nonuniform pressure, etc. must be avoided. Therefore, the welding electrode pressing jig of the prior art has a pair of electrically insulating semi-circular pressing surfaces suitable for forming a short tube on the inner peripheral surface.

The deviation of the abutting end is caused by the abutting portion on the inner peripheral surface.
It is corrected and fixed by pressing with the contact member. Since the welding is performed while pressing, the abutment member prevents the rising of the inner peripheral surface from occurring when the butt ends are appropriately melt-forged.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. As shown in FIG. 1, a steel plate is first punched by a pressing machine to provide a necessary short pipe member 1. Next, this member is applied to a bending roller machine and formed into a tubular shape to form the curved short tube 2 shown in FIGS. Next, the abutting portions 2a and 2b of the curved short tube 2 are connected to the electrodes 5a of the welding electrode pressing jigs 5 and 6 of the flash butt welding machine shown in FIG.
6a is placed in contact with and fixed by moving the upper die jig 5 in the figure. Each of the welding electrode pressing jigs 5 and 6 has an electric insulator 5
b, 6b, forming a pressing surface suitable for forming a short tube.

Next, as shown in FIG. 4, the contact member 7 held by the contact member holder 8 is brought into contact with the abutting end of the curved inner peripheral surface of the short tube 2. The contact member 7 has an arcuate shape suitable for forming a short pipe. The abutting member holder 8 having a taper holds the pair of abutting members 7 that press the inner peripheral surface of the curved short tube 2 outward in the horizontal direction. Between the pair of welding electrode pressing jigs 5 and 6, and the curved short tube 2
The positions of the end portions 2a, 2b and the top surface of the arc-shaped outer peripheral surface of the contact member 7 are the same.

Thereafter, as shown in FIG. 5, the contact member 7 held by the tapered contact member holder 8 is pressed by the cylinder 9c via the taper member 9a and the rod 9b of the pressing device 9, The correction is performed so that there is no gap between the abutting ends 2a and 2b of the curved short pipe and the inner peripheral surfaces of the welding electrode pressing jigs 5 and 6.

Next, a current is applied to the electrodes 5a and 6a to perform butt resistance welding. At this time, the melt forging is performed, but the contact member 7
By pressing with, the inner peripheral surface is prevented from rising and burr. If the abutting member 7 is not pressed against the butt end of the inner peripheral surface, as in the pre-finishing short pipe 3 in FIG.

After that, the bulge generated only on the outer peripheral surface is
By processing such as cutting only the outer peripheral surface, the short tube 4 after finishing in FIG. 1 is obtained.

The member suitable for the abutting member 7 is an electrically insulating material, such as a high-steel stone, which is resistant to repeated use of melt forged welding, and which is resistant to pollution of sparks and melt scattering, ceramics, etc. However, ceramic was used as appropriate.

[0014]

As described above, a curved short tube is butt resistance welded by using a welding electrode pressurizing jig while pressing an arcuate contact member against the butt end of the inner peripheral surface. Then, it is possible to prevent the welded portion from rising to the inner peripheral surface and prevent burrs, and it is possible to reduce a great number of man-hours and costs such as deburring, cutting and barrel polishing for finishing the inner peripheral surface.

The displacement of the abutting end is corrected and fixed by pressing the abutting member against the abutting end of the inner peripheral surface.
The poor strength of the welded part due to the deviation, the defective shape and dimensional defect of the formed short pipe are reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a process outline

FIG. 2 is a perspective view of a curved short tube.

FIG. 3 is a perspective view of a welding electrode pressing jig.

FIG. 4 is a sectional view of an example.

5 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 1: Short tube member 2: Curved short tube 2a, 2b: End of butt 3: Short tube before finishing 4: Short tube after finishing 5: Welding electrode pressing jig upper die 5a: Electrode 5b: Electric insulator 6: Welding Electrode pressing jig lower mold 6a: Electrode 6b: Electric insulator 7: Contact member 8: Contact member holder 9: Pressing device 9a: Taper member 9b: Rod 9c: Cylinder

Claims (1)

[Claims] 1. A semi-arcuate pressing surface of an electrical insulator suitable for forming a short tube is formed on a curved outer surface of a short tube after a steel sheet cut into a predetermined size is formed into a tubular shape. In a method for manufacturing a short pipe, in which a butt end of a curved short pipe is butt resistance-welded using a pair of welding electrode pressing jigs facing each other, At the butt end of the inner peripheral surface, butt resistance welding is performed while pressing an arc-shaped contact member of an electric insulator having a shape suitable for forming a short pipe in the direction of the electrode of the welding electrode pressing jig. A method for producing a short tube, which is characterized.