JPS6397381A - Friction welding method for thin wall pipe body - Google Patents

Abstract

PURPOSE:To form a satisfactory pressure welded part by forming a tapered part where the thin wall is formed from the equal diameter side toward the different diameter side on the jointing side end face of one side of a coupled of pipe bodies and pressure welding thereon to prevent the offset of a butt part. CONSTITUTION:The pipe body 1 is arranged concentrically with the pipe body 2 and the pipe body 1 is pressed against the pipe body 2 while rotating the pipe body 1 at a high speed by a driving means and a working means. At this time, the tapered part 3 is formed on the end face of the butting surface of the pipe body 1 with the thinner wall and both the pipe bodies 1 and 2 are pressed against each other. The tip of the tapered part 3 can be prevented from buckling by the butting surface 1a of the end face of the pipe body 1. As this result, the offset of the butt part is prevented and the satisfactory pressure welded part can be obtained in the pressure welding of the thin wall pipe bodies.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of friction welding thin-walled tubes, and more particularly to a method of friction-welding thin-walled tubes having the same outer diameter or inner diameter but different wall thicknesses.

[Conventional technology]

When connecting thin-walled tubes with a wall thickness of about 51 mm or less,
Usually, methods such as arc welding, brazing or soldering, and flash butt welding are used. Among these welding methods, arc welding, brazing, and soldering require auxiliary materials such as welding wire, shielding gas, brazing material, and flux, and have the disadvantage that welding takes a long time. In addition, when using flash butt welding, a large amount of flash occurs on the inner surface of the joint surface, which must be removed by post-processing, and high surface pressure is required during welding. The disadvantage is that it is difficult to apply.

A quick joining method with good workability is to arrange a pair of tubes concentrically, rotate one tube at high speed, hold the other tube still, and connect one tube to the other. There is a friction welding method in which the interface between the two tubes is pressed and melted by frictional heat, and then the tubes that rotate once are suddenly stopped and welded together. The friction welding method is disclosed in JP-A-55-86691. The proposal disclosed in Japanese Unexamined Patent Publication No. 55-16758 is publicly known.

[Problem that the invention seeks to solve]

However, according to the conventional friction welding method described above, as shown in FIG. When trying to do this, if t<12, then t/d<0
．． 03, there was a problem that friction welding was difficult.

The reason for this is that the heat generated during friction welding reduces the rigidity of the thin-walled tubular body 1.degree. 2 in the vicinity of the abutting portion, causing deformation due to the pressure applied during friction welding. As a result, as shown in FIG. 5, the abutting portions are pushed apart and the joint surfaces of both tubes 1 and 2 are tapered and deviated from each other.

Further, in the case of friction welding of thin-walled tubes having different wall thicknesses and the same inner diameter, the thinner-walled tube bites into the inner diameter side of the thicker tube, and a discrepancy in the joining surfaces similarly occurs.

A pair of thin-walled tubes 1 with different wall thicknesses and equal outer diameters,
2, the frictional heat generating part on the thick-walled tube 2 side is shifted toward the outer diameter side, and the temperature distribution in the wall thickness direction becomes uneven, so the friction surface becomes oblique as shown in Figure 5. Fortunately, the thin-walled tube body 1 was pushed outward and expanded by the pressurizing force. The same applies when the plate thicknesses are different and the inner diameters are the same. Due to this phenomenon, friction welding becomes impossible when t i/d <0.01.

The proposal disclosed in JP-A-55-16758 is to suddenly stop the rotating tube body after friction welding, and air-cool both tube bodies while maintaining the pressing force. The proposal disclosed in Publication No. 55-86691 is to chamfer the end of one tube and apply solder plating to the chamfered part, but these proposals all have equal diameter and equal thickness. This method is for friction welding a pair of thin-walled tubes, and no consideration was given to friction welding of thin-walled tubes with different wall thicknesses.

The present invention has been made in view of the above-mentioned circumstances, and is intended to prevent discrepancies in the abutting portions when joining a pair of thin-walled tubes having equal outer diameters or inner diameters and different wall thicknesses by friction welding. It is an object of the present invention to provide a method of friction welding of thin-walled tubes that can obtain a press-welded part.

[Means for solving the problem]

In order to achieve the above object, the present invention includes a pair of thin-walled tubes having the same outer diameter or inner diameter and different wall thicknesses, arranged concentrically, one of the tubes being rotated at high speed, and the other being stationary. , in a friction welding method for thin-walled tubes, in which the interface between the two tubes is melt-welded by frictional heat by pressing one tube against the other tube, the bonding side end surface of one of the pair of tubes is , a tapered portion that becomes thinner from the rear side toward the side with a different diameter is formed so as to be press-contacted.

[Effect]

According to the above method, heat generation at the butt end faces during friction welding starts from the different diameter side and gradually spreads to the equal rear side, so that the softening of the thicker tube body occurs only on the equal rear side. It is possible to prevent the occurrence of misalignment of the ends of the tubes at the abutting portions.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the friction welding method for thin-walled tubes according to the present invention will be described with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 to 3.

In these figures, parts that are the same or equivalent to those of the conventional example shown in FIG. 4 are denoted by the same reference numerals. The features of this example are 1
A tapered portion 3 is formed on the end face of the abutting surface of the thinner tube of the pair of thin-walled tubes at the point of pressure contact.In this embodiment, both tubes 1 and 2 are made of electric resistance welded steel pipes. are doing. The dimensions and angles of each part of the tubular bodies 1 and 2 shown in FIGS. 1 and 2 were set as shown in Table 1 below.

Table 1 However, D and D2 are the outer diameter of the thick-walled tube 2, respectively, and the inner diameter #dLl d is the outer diameter of the thin-walled tube 1, respectively.
The inner diameter, W, is the width of the abutting surface 1a of the tube body 1.

α is the angle of the tapered part 3 in the axial direction, Q is the axial length of the tapered part, and tl is the wall thickness of the tube body 1 (=1.5nwn)
It is.

Next, the processing procedure according to this embodiment will be explained. The tubular body 2 is held by a fixed holding means (not shown), the tubular body 1 is arranged concentrically with the tubular body 2, and the tubular body 1 is rotated at high speed by a driving means and a processing means (not shown). Press 2. At this time, the interface between the two tubes 1 and 2 becomes molten due to frictional heat.

Thereafter, the rotation of the tubular body 1 is abruptly stopped and the joining is performed. The amount of axial movement of the tube 1 at this time is approximately 4 mm, and the axial length fl (=3nwn) of the tapered portion 3 formed in the tube 1
) is longer.

Next, the operation and effects of this embodiment will be explained.

When the tubular bodies 1 and 2 are brought into pressure contact and pressure starts to be applied, the abutment surface 1a formed on the end face of the tubular body 1 can prevent the tip of the tapered portion 3 from buckling.

When the tube body 1 rotates at high speed and is pressed against the tube body 2, heat generation during friction welding starts from the inner diameter side of the end surface of the tube body 2 and gradually expands to the outer diameter side. For this reason, tube body 1
It is possible to prevent the end faces from shifting toward the outer diameter side of the tube body 2 and becoming mismatched.

Figure 3 shows the state after pressure welding. The joint width is greater than the wall thickness of tube body 1, and the joint surfaces of both tube bodies 1 and 2 are almost perpendicular to the axial direction without being inclined, resulting in good pressure welding. Section 4 is formed. Reference numeral 5 indicates a gap formed by plastic deformation of the material of the joint portion of the tubes 1 and 2 during friction welding.

The welding width at the end of friction welding is approximately 4 LII the amount of movement of tube body 1.
Since L is larger than the axial length Q (3rrn+) of the tapered portion 3, it is ensured that the wall thickness is greater than the wall thickness of the tube body 1.

Further, the amount of movement is set to be less than twice the length Q of the tapered portion to prevent misalignment of the tubes 1 and 2 due to an excessive amount of movement.

In the above embodiment, a case has been described in which the outer diameters of the tubes 1 and 2 are equal and the wall thicknesses are different. However, when the inner diameters of the tubes 1 and 2 are equal and the wall thicknesses are different, the taper of the tapered part 3 is set in the opposite direction.
The outer diameter of the thin-walled tube body 1 may be thinner and the inner diameter side may be tapered to be thicker, and similar effects can be obtained. Further, the dimensions of each part shown in Table 1 are not limited to these, and other dimensions may be used without departing from the gist of the present invention.

Although the present embodiment has been described with reference to the case where the tubular bodies 1 and 2 are electric resistance welded steel pipes, the tubular bodies 1 and 2 are not limited to this.

〔Effect of the invention〕

As described above, according to the present invention, when a pair of thin-walled tubes having equal outer diameters or inner diameters and different wall thicknesses are joined by friction welding, a different diameter is formed on the joining side end surface of one tube from the equal diameter side. Since a tapered portion that becomes thinner toward the side is formed for pressure welding, it is possible to prevent the discrepancy between the abutting portions of both tube bodies during friction welding, and to obtain a good pressure welding portion.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the friction welding method for thin-walled tube bodies according to the present invention, FIG. 2 is an enlarged cross-sectional view showing the abutting portion of FIG. 3 is a cross-sectional view showing the joint according to this embodiment, FIG. 4 is a longitudinal cross-sectional view showing a conventional friction welding method for thin-walled tubes, and FIG. 5 is a cross-sectional view showing the discrepancy phenomenon of the joint in FIG. 4. It is. 1.2...Thin-walled tube body, 3...Tapered part.

Claims (1)

[Claims] (1) A pair of thin-walled tubes having the same outer diameter or inner diameter and different wall thicknesses are arranged concentrically, one of the tubes is rotated at high speed,
In a friction welding method for thin-walled tubes, in which the interface between the two tubes is melt-welded by frictional heat by pressing one tube against the other while the other is stationary, one of the pair of tubes is A method of friction welding thin-walled tubes, characterized in that a tapered portion that becomes thinner from an equal-diameter side toward a different-diameter side is formed on an end face of a joining side, and the welding is performed by pressure.