JPH06231878A - High frequency welding device for seam welded pipe - Google Patents

Abstract

PURPOSE:To provide a high frequency welding device for a seam welded pipe, capable of reducing inductance and leakage flux at the lead section of a work coil, improving welding performance and preventing the overheat of a roll stand. CONSTITUTION:A band plate is rounded like a tubular form, thereby preparing a tube element 6 and, while the element 6 being caused to travel, both ends thereof are press connected to each other with a pair of squeeze rolls 7. The coil section 12d of a work coil 12 connected to a high frequency power supply is laid around the element 6 at a position near the front side of the squeeze rolls 7 for the induction heating of the edge 6a of the element 6. At the same time, three sides of one lead section 12a of the coil 12 at the side of the rolls 7 are surrounded with the other lead section 12b, thereby offsetting leakage flux generated from the lead sections 12a and 12b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency electric resistance welded pipe welding apparatus, and more particularly to a work coil thereof.

[0002]

2. Description of the Related Art FIGS. 3 (A) and 3 (B) are a front view and a side view of a main part of a conventional high frequency electric resistance welded pipe welding apparatus, and FIG. 4 is a line MM of FIG. 3 (B). A sectional view is shown. In the figure,
Reference numeral 1 denotes a pair of secondary leads of an output transformer of a high frequency power source, which are integrally formed with an insulating plate 2 interposed therebetween. Reference numeral 11 denotes a pair of mounting seats mounted on the pair of secondary leads 1 by screws 3, respectively. Reference numeral 4 denotes a hollow work coil having both ends attached to the mounting seat 11, and a pair of lead portions 4a connected to the mounting seat 11, a coil-shaped coil portion 4b formed at the tip of the lead portion 4a, and a lead. The heat-resistant insulating plate 4c is formed on the surfaces of the portion 4a and the coil portion 4b. 5 is connected to both ends of the work coil 4,
It is a cooling water pipe for flowing cooling water into the work coil 4.

Reference numeral 6 denotes a tube material formed by continuously rolling a strip plate into a tubular shape. Reference numeral 7 denotes a pair of squeeze rolls that press the edges 6a of the tube material 6 from both sides.
Is the axis of rotation. The coil portion 4b of the work coil 4 is coaxially arranged so as to surround the pipe material 6 in the vicinity of the squeeze roll 7.

The arrow 9 indicates the moving direction of the tube material 6. Therefore, the coil portion 4b is arranged at a position close to the front side of the squeeze roll 7. Further, FIG. 5 shows a schematic configuration diagram of a conventional high frequency electric resistance welded pipe welding apparatus, 8 is an output transformer of a high frequency power supply, and the output of the output transformer 8 is the secondary lead 1 and the mounting seat 11 which are omitted in FIG. It is supplied to the work coil 4 via. A pair of roll stands 10 rotatably supports the squeeze roll 7.

In the high frequency electric resistance welded pipe welding apparatus having the above structure, the output of the output transformer 8 of the high frequency power source is the secondary lead 1.
And is supplied to the work coil 4 via the mounting seat 11.
The pipe material 6 is moved in the direction of the arrow 9 while pressing the edge portion 6a by a pair of squeeze rolls 7, and the coil portion 4b of the work coil 4 is coaxial with the periphery of the pipe material 6 near the front side of the squeeze roll 7. It is installed in. As a result,
The high frequency current flowing in the coil portion 4b causes a high frequency induction current to flow in both edge portions 6a of the tube material 6 to heat both edge portions 6a, and the squeeze roll 7 press-bonds them to form an electric resistance welded pipe. The work coil 4 itself also generates heat, so that cooling water is circulated inside and cooled.

[0006]

As described above, in the conventional high frequency electric resistance welded pipe welding apparatus, since the coil portion 4b of the work coil 4 is disposed close to the squeeze roll 7, the mounting seat 11 and the squeeze roll 7 are provided. Further, the work coil 4 is provided with a lead portion 4a in order to avoid physical interference with the roll stand 10. Further, in the case of manufacturing a tube of a normal size, the roll stand 10 generally has a structure in which the rotating shaft 7a of the squeeze roll 7 is supported by a cantilever as shown in FIG. There is no electromagnetic interference with the mounting seat 11.

However, small diameter thick wall (for example, diameter 3
When manufacturing an electric resistance welded pipe having a thickness of 4 mm and a thickness of 6 mm), it is necessary to increase the pressure applied by the squeeze roll 7 to the pipe material 6, so that the rigidity of the roll stand 10 must be increased. The shaft 7a also has to be supported at both ends as shown in FIG. 6 and FIG.
0 became large. On the other hand, in order to improve the welding efficiency (electrical efficiency), it is necessary to make the distance L ₁ between the center of the squeeze roll shaft 7a and the work coil 4 as small as possible. Therefore, the diameter D of the squeeze roll 7 needs to be made small. was there. Therefore, from the top of the roll stand 10, the pipe material 6
The distance L ₂ to the center of the work coil was, for example, 200 to 300 mm, and the length of the lead portion 4 a of the work coil 4 had to be increased. Therefore, the amount of inductance of the lead portion 4a increases, the power loss in the lead portion 4a increases, the voltage of the coil portion 4b decreases, and the amount of electric power supplied from the coil portion 4b to the pipe material 6 decreases. The ability has decreased.
Further, the leakage flux of the lead portion 4a becomes large, and the roll stand 10 adjacent to the lead portion 4a is induction-heated by this leakage flux and becomes in an overheated state.

The present invention has been made to solve the above problems, and can greatly reduce the inductance and leakage flux of the lead portion of the work coil, enhance the welding capability, and improve the roll stand. An object of the present invention is to obtain a high frequency electric resistance welded pipe welding device capable of preventing overheating.

[0009]

A high frequency electric resistance welded pipe welding apparatus according to the present invention includes a work coil for supplying high frequency electric power to a pipe material, the other of which is provided so as to surround at least the squeeze roll side of one lead portion of the work coil. The lead part is formed.

[0010]

In the present invention, the other lead portion of the work coil is formed so as to surround at least the squeeze roll side of the one lead portion, and the leakage fluxes generated from the respective lead portions have opposite directions. The leakage flux is canceled out, and the leakage flux especially on the squeeze roll side is greatly reduced. In addition, the inductance of the lead portion also decreases as the leakage flux decreases.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 (A) and 1 (B) are a front view and a side view of a main part of a high frequency electric resistance welded pipe welding apparatus according to this embodiment, and FIG. 2 is a sectional view taken along line NN of FIG. 1 (B). Show. In the figure, 12 is a hollow work coil having both ends attached to the mounting seat 11, and a pair of lead portions 12a and 12b mounted to the mounting seat 11 and a thickness provided between the lead portions 12a and 12b are Thin (usually 2 mm or less) insulating material 12c
And a coil-shaped coil portion 12d formed at the tips of the pair of lead portions 12a and 12b, and a heat-resistant insulating portion 12e formed on the surface of the coil portion 12d.

Cooling water pipes 5 are connected to both ends of the lead portions 12a and 12b in the same manner as in the conventional case, and the cooling water flows through the work coil 12. The coil portion 12d is coaxially arranged so as to surround the periphery of the pipe material 6 at a position close to the front side of the squeeze roll 7 as in the conventional case, and the other lead portion 12b surrounds one lead portion 12a. It is formed so as to surround three sides of the squeeze roll side. Other configurations are the same as the conventional one.

In the high frequency electric resistance welded pipe welding apparatus having the above structure, the output of the output transformer 8 is the secondary lead 1 and the mounting seat 1.
1 is supplied to the work coil 12 through the coil portion 12
A high frequency induction current flows through the both edge portions 6a of the tube material 6 by the high frequency current flowing in d, the both edge portions 6a are heated, and the squeeze rolls 7 are pressed and joined.

In the above embodiment, one lead portion 1
Since three sides of the squeeze roll 7 side of 2a are surrounded by the other lead portion 12b via the thin insulating material 12c, the leakage flux generated by the high frequency current flowing through the lead portion 12a and the lead portion 12b are separated. The leakage flux generated by the flowing high-frequency current is canceled in the opposite direction, and the leakage flux is greatly reduced, especially the leakage flux to the squeeze roll 7 side is significantly reduced. Therefore, overheating of the roll stand 10 is prevented, the life of the roll stand 10 and its bearing portion is significantly extended, and water cooling of the roll stand 10 and the non-magnetic material of the roll stand 10 are not required, and the cost can be reduced. . Further, since the leakage flux is reduced as described above, the inductance of the lead portions 12a, 12b is also reduced to about 1/7 per unit length, the power loss in the lead portions 12a, 12b is reduced, and the coil portion 12d is reduced. The voltage rises and the welding capacity improves.

In the above embodiment, the lead portions 12a, 12
Although the cross section of b is rectangular, the present invention is not limited to this, and one lead portion may be surrounded by the other lead portion so that the leakage fluxes in opposite directions cancel each other. Further, the insulating material 12c is interposed between the lead portions 12a and 12b, which makes it possible to make the gap between the lead portions 12a and 12b uniform, but it is not always necessary to provide the insulating material 12c, and air insulation by a mere gap is not necessary. But it's okay.

[0016]

As described above, according to the present invention, at least the squeeze roll side of one lead portion of the work coil is surrounded by the other lead portion, so that it is generated from each lead portion. Leakage flux is offset, leakage flux is greatly reduced, especially leakage flux to the squeeze roll side is reduced,
The roll stand is prevented from overheating. Further, since the inductance of the lead portion is also reduced, the power loss in the lead portion is reduced, the voltage of the coil portion is increased, and the welding ability is improved. Therefore, it is particularly effective when the lead portion becomes long as in the case of manufacturing a thick-walled small-diameter tube.

[Brief description of drawings]

FIG. 1 is a front view and a side view of a main portion of a high frequency electric resistance welded pipe welding apparatus according to the present invention.

FIG. 2 is a sectional view taken along the line NN of FIG.

FIG. 3 is a front view of a main part and a side view of the main part of a conventional high frequency electric resistance welded pipe welding apparatus.

FIG. 4 is a sectional view taken along line MM in FIG.

FIG. 5 is a schematic configuration diagram of a conventional high frequency electric resistance welded pipe welding apparatus.

FIG. 6 is a schematic configuration diagram of another conventional high-frequency electric resistance welded pipe welding apparatus.

FIG. 7 is a side view of a squeeze roll and a roll stand of another conventional high-frequency electric resistance welded pipe welding apparatus.

[Explanation of symbols]

 6 ... Tube material 6a ... Edge 7 ... Squeeze roll 8 ... Output transformer 10 ... Roll stand 12 ... Work coil 12a, 12b ... Lead part 12d ... Coil part

Claims (1)

[Claims] 1. A pair of squeeze rolls formed by rolling a strip into a tubular shape and pressing both edges of a tubular material that is moved in the axial direction from both sides, and a pair that rotatably supports each squeeze roll. Roll stand, a pair of lead parts connected to a high frequency power source, and a coil part formed in a coil shape at the tip of the lead part and coaxially arranged around the tube material at a position close to the squeeze roll front side. In a high-frequency electric resistance welded pipe welding apparatus including a work coil made of, a high-frequency electric resistance welding is provided in which the other lead portion is formed so as to surround at least the squeeze roll side of one lead portion of the work coil. Pipe welding equipment.