JPH0890228A - Internal clamp device - Google Patents

Abstract

PURPOSE: To obtain good penetration bead as well as to greatly suppress deformation, strain in joining the high alloy steel tube of stainless steel tube, etc., by one side welding. CONSTITUTION: The clamp head alternately arranged with A head 6a and B head are strongly welded with pressure at the inner face of welding zone of piping by pressing device. In welding, inert gas is supplied from a gas supply hole 18 of each head into the gaseous chamber 24 formed with the recessed part of lower center part of backing copper plates 19, 20, inert gas is injected into the inside of welding joint part from plural gas discharge holes arranged in the backing copper plate 19, 20, the air inside welding joint part is purged, the inside is filled with inert gas and weld metal is shielded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal clamp device used when welding and connecting steel pipes, and particularly to a favorable backside bead when welding high alloy steel pipes such as stainless steel pipes.
It is about the formation of the de.

[0002]

2. Description of the Related Art When joining steel pipes, for example, stainless steel pipes by single-sided welding, in order to prevent oxidation of the back-beads and to form good back-beads, for example, argon or nitrogen is not used. It is necessary to back shield the back bead portion with active gas. In this way, the backside bead is back-shielded.
For example, Japanese Patent Laid-Open No. 60-221174 and Shokai Sho
Various devices are used as disclosed in JP-A-60-66691.

The back shield device disclosed in Japanese Patent Laid-Open No. 60-221174 has a pipe 25 as shown in the sectional view of FIG.
When one side of a and 25b is welded, two sets of inflatable balloon bodies 42a and 42b connected by the communication pipe 41 are connected to the pipe 25.
Installed on both sides of the welded joint of a and 25b, the balloon body 42
The back shield chamber 44 is formed inside the welded joint by expanding a and 42b with compressed air supplied from the hose 43.
An inert gas is introduced into the back shield chamber 44 from the hose 45 to eliminate air in the back shield chamber 44, and the inside of the welded joint is shielded with the inert gas. Further, the seal device disclosed in Japanese Utility Model Publication No. 60-66691 is
As shown in the partial sectional view of FIG. 10, a circular frame 5
An inflatable tube 52 fitted to the outer peripheral portion of 1.
It has a backing plate 53 attached to the outer peripheral surface of the tube 52 and having a recessed portion over the entire circumference. This seal device is pipe 2
5a and 25b are arranged at the welded joints, and the tube 52 is expanded by the compressed air supplied from the hose 54 so that the pad 5
The both ends of 3 are pressed against the inner surfaces of the pipes 25a and 25b,
A back shield chamber is formed by the inner surfaces of 5a and 25b and the recess of the contact plate 53, and an inert gas is fed from the hose 55 to the back shield chamber.

[0004]

Stainless steel has significantly different physical properties from mild steel, and this difference has a great effect when welding. That is, the Young's modulus, density, and specific heat of stainless steel are about the same as those of mild steel, but the coefficient of thermal expansion is about 1.5 times that of mild steel, and the thermal conductivity is about 1/3 that of mild steel.
And small. For this reason, the cooling rate after welding becomes much slower than in the case of mild steel, and the deformation and strain due to welding are likely to be greater than in the case of mild steel.

On the other hand, in the above-mentioned conventional back shield device, the balloon bodies 42a, 42b and the tube 52 are inflated by air pressure and pressed against the inner surfaces of the pipes 25a, 25b, but this occurs when welding a stainless steel pipe. It was not possible to suppress deformation and strain, and there was a problem in that the appearance of the joint after welding the stainless steel pipe had the shape of an inverted bamboo node.

The present invention has been made to solve the above problems, and when a high alloy steel pipe such as a stainless steel pipe is joined by single-sided welding, a good backside bead can be obtained and deformation or distortion can be obtained. It is an object of the present invention to obtain an internal clamp device capable of significantly suppressing

[0007]

An interface according to the present invention.
The null clamp device has a clamp head attached to a plurality of pressurizing devices that can expand and contract in the pipe radial direction,
Two types of heads are alternately arranged in the clamp head, one end is formed in a fan shape at both ends, and the other head is formed in an inverted fan shape at both ends at the same angle as the fan end. In an internal clamp device that presses the backing material attached to the center of the outer peripheral surface of each head against the inner surface of the welded part of the pipe, each head is supplied with gas that penetrates to the center backing material holding groove. Each backing material has a hole, and each backing material has a recess formed in the center of the lower part and a plurality of gas release holes communicating the recess and the outer surface of the upper part.

[0008]

According to the present invention, the clamp head, in which two kinds of heads having the backing material fixed to the backing material holding groove on the outer surface are alternately arranged, is firmly pressed against the inner surface of the welded portion of the pipe by the pressurizing device. Then, the pipes to be welded are aligned with each other and the flatness of the pipe at the welded joint is corrected.

At the time of welding, an inert gas is supplied from the gas supply holes of each head to the air chamber formed by the surface of the backing material holding groove and the recess in the lower central portion of the backing material, and a plurality of backing materials are provided. Inert gas is ejected from the gas discharge hole into the welded joint portion to eliminate air in the welded joint portion and fill it with inert gas to shield the weld metal.

Further, the clamp head is strongly pressed against the inner surface of the welded portion by a pressurizing device, and welding is performed while the periphery of the welded joint is strongly constrained to suppress deformation and distortion due to welding.

[0011]

1 and 2 show the interface of an embodiment of the present invention.
FIG. 1 is a side sectional view and FIG. 2 is an AA sectional view of FIG. Internal clamp device 1
A plurality of fixing clamps 4 are radially provided at one end of a cylindrical main body 3 having a plurality of traveling wheels 2. Each fixing clamp 4 is connected to a hydraulic cylinder 5 provided inside the main body 3, and expands and contracts by hydraulic oil supplied to the hydraulic cylinder 5. A plurality of clamp heads 6 are radially provided on the other end of the main body 3.

As shown in the side view of FIG. 3, the clamp head 6 has a plurality of, for example, four A heads 6a whose both ends are formed in a fan shape, and both ends are opposite to each other as shown in the side view of FIG. It has a plurality of, for example, four B heads 6b formed in a fan shape, and A heads 6a and B heads 6b are arranged alternately. A plunger 7 is fixed to central portions of the inner surfaces of the A head 6a and the B head 6b. 2 in the main body 3
Hydraulic and pneumatic cylinders 8 and 9 for expanding a pair of heads
Have. Then, one fluid cylinder 8, a support block 11 connected to the piston 10 of the fluid cylinder 8 and having a plurality of teeth on the outer peripheral portion, and one end portion of the support block 1
A head 6 with an arm 12 and a plunger 7 rotatably attached to one tooth portion and the other end rotatably attached to a plunger 7 fixed to the A head 6a.
It constitutes the pressurizing device of a. Further, the other fluid cylinder 9, a support block 14 with a claw that is connected to the piston 13 of the fluid cylinder 9 and has a groove on the outer periphery of the tip that fits with the teeth of the support block 11, and a support block with a claw at one end. The arm 12 and the plunger 7 rotatably attached to the tip claw portion 14 and the other end rotatably attached to the plunger 7 fixed to the B head 6b add the B head 6b. It constitutes a pressure device.

The outer peripheral surfaces of the A head 6a and the B head 6b are formed as convex curved surfaces having a radius matching the inner radius of the pipe to be welded, and the cross-sectional views of FIG. As shown in the sectional view of FIG. 1, backing material holding grooves 15 and 16 are provided and are connected to a shield gas feed hose (not shown) provided on the side surface or the lower surface of the A head 6a and the B head 6b. A gas supply hole 18 penetrating from the screw portion 17 to each of the backing material holding grooves 15 and 16 is provided. The backing copper plates 19 and 20 are inserted into the backing material holding grooves 15 and 16, and are fixed by a plurality of fixing screws 21 from the side surface. The backing copper plates 19 and 20 each have an outer peripheral surface formed of a convex curved surface having a radius matching the inner radius of the pipe to be welded, and are the same as the backing material holding grooves 15 and 16 of the A head 6a and the B head 6b. It has a length, and as shown in the sectional views of FIGS. 5 and 6, the central portion is recessed from both sides by a certain depth d. If the depth d of this recess is less than 0.5 mm, the penetration will be insufficient, and if it is more than 1 mm, the backside will be too convex, and a good backside bead can be obtained by setting it to about 0.8 to 1 mm. You can Also, the backing copper plate 1 attached to the A head 6a
Both end faces of 9 are formed in a fan shape with the same inclination as both end faces of the A head 6a, and both end faces of the backing copper plate 20 attached to the B head 6b are formed in an inverted fan shape with the same inclination as both end faces of the B head 6b. Has been done. Further, as shown in the A head sectional view of FIG. 7 and the B head sectional view of FIG. 8, recesses 22 are provided in the lower central portions of the backing copper plates 19 and 20, and each recess 22 communicates with the upper outer surface. A plurality of gas emission holes 23 are provided. When the backing copper plates 19 and 20 are attached to the A head 6a and the B head 6b, respectively, the upper surfaces of the backing material holding grooves 15 and 16 and the recesses 22 form an air chamber 24 that fills the shield gas.

When a high alloy steel pipe such as a stainless steel pipe is welded on one side to be joined, as shown in FIG. 1, the internal clamp device 1 is inserted into one of the pipes 25a to be joined, and the A head 6a and The position of the internal clamp device 1 is adjusted so that the center of the backing copper plates 19 and 20 attached to the B head 6b coincides with the groove line of the pipe 25a, and then the fixing clamp 4 is extended to the internal. The clamp device 1 is fixed to the tube 25a. Then the other tube 2
5b is a pipe 25a to which the internal clamp device 1 is fixed
And pull out the A head 6a lightly to the tube 2
5a and 25b are temporarily set. Then, the positions of the pipes 25b are adjusted so that the root interval is within a specified range, and then the A head 6a and the B head 6b are strongly projected to both pipes 25.
The A head 6a and the B head 6b are fixed inside the circumferential joints of a and 25b. In this way, the A head 6a and the B head 6b forcibly correct the flatness in the vicinity of the circumferential joints of the pipes 25a and 25b by applying and suppressing a strong load near the circumferential joints of the pipes 25a and 25b. Then the tubes 25a, 25b
It is possible to perform accurate centering and prevent the root interval from varying during welding.

When the A head 6a and the B head 6b are expanded, one of the fluid cylinders 8 is first actuated to project the A head 6a having fan-shaped ends, and then the other fluid cylinder 9 is extended. When it is operated to project the B head 6b having both ends formed in a reverse fan shape,
The end surface of the head 6a, the end surface of the B head 6b, the end surface of the backing copper plate 19 and the end surface of the backing copper plate 20 can be adhered to each other, and the flatness in the vicinity of the circumferential joints of the pipes 25a and 25b can be forcibly corrected. While backing the entire inside of the circumferential joint, copper plate 1
It can be covered with 9,20.

In this state, the shield gas feed hose
A shield gas such as argon or nitrogen is supplied to the head 6a and the B head 6b, and the shield gas is sent to the air chamber 24 from the gas supply holes 18 of the A head 6a and the B head 6b. Air chamber 24
Shield gas sent to A head 6a and B head 6b
The air discharged from the plurality of gas discharge holes 23 inside the circumferential joint portion and covered with the backing copper plates 19 and 20 is discharged to be back-shielded with the shield gas. In this way, since the shield chamber is directly formed inside the circumferential joint portion by the backing copper plates 19 and 20, the shield gas is supplied,
It is possible to prevent the molten metal from being oxidized by the shield gas when the circumferential joints of the pipes 25a and 25b are welded on one side and to increase the cooling rate with the backing copper plates 19 and 20.
A good backside bead can be formed.

During welding, the A head 6a and the B head 6
b holds the pipes 25a, 25b near the circumferential joint strongly.
Since it is restrained, it is possible to suppress the deformation and strain of the pipes 25a and 25b made of stainless steel, which have large thermal deformation and strain during welding, and it is possible to obtain a weld joint without strain.

After welding the entire circumferences of the circumferential joints of the pipes 25a and 25b, the fluid cylinder 9 is operated to reduce the B head 6b having opposite fan-shaped ends, and then the fluid cylinder 8 is operated. Then, the A head 6a having both ends formed in a fan shape is contracted to release the clamp by the internal clamp device 1. After that, the fixing clamp 4 is reduced and the tubes 25a, 25 to which the internal clamp device 1 is joined.
Remove from b and finish the welding work.

[0019]

As described above, according to the present invention, when the pipes are joined by single-sided welding, the shield chamber is formed directly inside the circumferential joint portion by the backing material so that the gas releasing hole of the backing material is formed. Since the shield gas is supplied from the inside, the inside of the circumferential joint can be reliably backshielded, the molten metal can be prevented from being oxidized, and the cooling rate can be increased by the backing material. The beads can be stably formed.

Further, since the vicinity of the circumferential joint portion of the pipe joined by the clamp head during welding is strongly held and restrained,
It is possible to suppress the deformation and strain of a high alloy steel pipe such as a stainless steel pipe having a large thermal deformation and strain at the time of welding, and it is possible to obtain a good welded joint having no deformation or strain.

[Brief description of drawings]

FIG. 1 is a side sectional view of an internal clamp device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of the above embodiment.

FIG. 3 is a side view showing an A head of the above embodiment.

FIG. 4 is a side view showing the B head of the above embodiment.

FIG. 5 is a BB cross-sectional view of the A head.

FIG. 6 is a sectional view taken along line CC of the B head.

FIG. 7 is a sectional view of the A head.

FIG. 8 is a sectional view of the B head.

FIG. 9 is a cross-sectional view showing a conventional example.

FIG. 10 is a sectional view showing a part of another conventional example.

[Explanation of symbols]

 1 Internal Clamp Device 4 Fixing Clamp 6 Clamp Head 6a A Head 6b B Head 7 Plunger 8 Fluid Cylinder 9 Fluid Cylinder 15 Backing Material Retaining Groove 16 Backing Material Retaining Groove 18 Gas Supply Hole 19 Backing Copper Plate 20 Backing Copper Plate 22 Recess 23 Gas Release Hole 24 Air Chamber 25a Tube 25b Tube

Claims (1)

[Claims] 1. A clamp head, which is attached to a plurality of pressurizing devices capable of expanding and contracting in a pipe radial direction, in which two types of heads are alternately arranged, and one head has both end portions. The head is formed in a fan shape, and both ends of the other head are formed in a reverse fan shape at the same angle as the end of the fan shape, and the backing material attached to the central portion of the outer peripheral surface of each head is welded to the pipe at the welding point. In the internal clamp device that presses against the inner surface of each of the heads, each head has a gas supply hole that penetrates to the backing material holding groove in the central portion, and each backing material has a concave portion provided in the lower central portion. An internal clamping device having a plurality of gas discharge holes communicating the recess and the upper outer surface.