JPH09136159A - Restarting method for pipe welding and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a restarting method for pipe welding capable of easily executing restarting of pipe welding many times after welding is once interrupted and executing the restarting to the welding state similar to the welding state at the stationary time. SOLUTION: A microcomputer 15 supplies a welding current to a welding torch 4 when this welding torch 4 is moved in the progressing direction of a tubular body 2 from an origin P0 until this torch arrives at a welding start point P1 while the tubular body 2 is held stopped. This microcomputer stops supplying the welding current and rests the welding torch 4 to the origin P0 when the welding torch 4 arrives at a welding stop point P2 past the origin P0. The microcompulter supplies the welding current to the welding torch 4 while moving the tubular body 2 in the progressing direction. Namely, the welding is executed while the welding torch 4 moves forward and backward at the welding interruption point as a center before the pipe welding is restarted and, therefore, the parts before and behind the welding interruption point of the tubular body 2 are preheated and the stationary welding of the pipe is executed even if the restarting of the pipe welding is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe welding restart method and apparatus.

[0002]

2. Description of the Related Art As a method of forming a pipe, there is a method of moving a metal tape in a longitudinal direction while molding it into a cylindrical shape so that its longitudinal axis and a central axis are parallel to each other, and welding the boundary by TIG welding. is there.

FIG. 6 is a conceptual diagram of a pipe welding apparatus to which a conventional pipe welding method is applied.

In FIG. 1, reference numeral 1 denotes a tubular body 2 as a work in which a metal tape is molded in a cylindrical shape, in a traveling direction (arrow A).
It is a tubular body moving means for moving in the direction). A ground brush 3 is provided below the tube 2 delivered to the outlet side of the tube moving means 1.
Is provided. A welding torch 4 is fixed to the upper side of the tubular body 2 on the outlet side of the tubular body moving means 1, and an electrode 5 thereof is provided.
Is approaching the boundary of the pipe body 2. The ground brush 3 and the welding torch 4 are connected to the welding power source 6.
The pipe moving device 1, the ground brush 3, the welding torch 4, and the welding power source 6 constitute a pipe welding device 7.
The filler wire, the cooling system and the inert gas system are omitted.

In the pipe welding apparatus 7 shown in FIG. 6, the pipe 8 is formed by moving the pipe body at a work moving speed as shown in FIG. 7 and supplying a welding current as shown in FIG. 8 to the welding torch. It FIG. 7 is a diagram showing the work moving speed of the pipe welding apparatus shown in FIG. 6, where the horizontal axis is the time axis and the vertical axis is the work moving speed axis. FIG. 8 shows FIG.
It is a figure which shows the welding current of the pipe welding apparatus shown in FIG. 4, and a horizontal axis is a time axis and a vertical axis is a welding current axis. However, the time axis of FIG. 7 and the time axis of FIG. 8 are common.

[0006] In such a pipe welding apparatus, when the welding is once interrupted due to some cause such as a failure or a power failure and then the pipe welding is performed again, a defective welding may occur in the restarted portion, but conventionally it is not so problematic. It didn't.

This is because it is not necessary for the restart portion to be equivalent to that of a product in a completely steady state, and the technique has not been studied much.

However, since demands for improving the quality and yield of pipes are gradually increasing, attempts have been made to restart the pipes.

The restart of the pipe welding was slightly carried out by a toflex machine (a machine in which a metal tape is rounded in the longitudinal direction, the butt is welded, and the whole is corrugated). , It is a method of simply returning the work in the welding torch part in the direction opposite to the direction of travel of the work. This method does not have any special idea for the welding torch and simply starts welding.

[0010]

However, in the above-mentioned conventional method, the work is returned to overlap the welded portions and re-weld. However, since the pipe welding apparatus does not start up immediately after re-welding, the work of The movement precedes and the arc does not occur sufficiently at the place to be welded, and there are parts that cannot be welded,
On the contrary, since the start of movement of the work is delayed and the arc is generated too much at the place to be welded and a hole is opened, the probability of successful restart of welding is low and it tends to be unstable. Further, when the work has a molding step and becomes large in size and weight, it is very difficult to return the work after molding in the opposite direction.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and to restart the pipe welding after the welding is temporarily stopped as many times as needed, and further, to perform the same welding condition as in the steady state. It is to provide a restart method and an apparatus thereof.

[0012]

In order to achieve the above-mentioned object, the present invention forms a pipe by welding the boundary of the tubular body while moving the tubular body formed by molding a metal tape into a cylindrical shape along the longitudinal direction. In the method of restarting pipe welding, in which the welding is temporarily stopped and then pipe welding is performed again, the welding torch is moved from the origin in the traveling direction of the pipe while the pipe is stopped, and the welding torch When the position is reached, the welding torch is moved in the opposite direction and the welding current is supplied to the welding torch, and when the position reached a certain distance from the origin is reached, the welding current is stopped and then the welding torch is returned to the origin. The welding current is supplied to the welding torch while moving the pipe body in the traveling direction.

Further, according to the present invention, there is provided a tubular body moving means for moving a tubular body formed by molding a metal tape into a cylindrical shape along a longitudinal direction, and a welding torch for welding a boundary between the tubular bodies to form a pipe. , A power source for supplying a welding current to the welding torch, a welding torch moving means for moving the welding torch along the longitudinal direction of the pipe body, and a pipe body being stopped when restarting after temporarily interrupting the pipe welding , Move the welding torch from the origin in the traveling direction of the pipe, and when the welding torch reaches a predetermined position, move the welding torch in the opposite direction and supply the welding current to the welding torch at a position apart from the origin by a certain distance. When the welding current reaches, the welding current is stopped, the welding torch is returned to the origin, and the welding current is supplied to the welding torch while moving the pipe body in the traveling direction. In addition to the above configuration, the present invention may use a screw engaged with the welding torch and a motor for rotating the screw to move the welding torch.

With the above structure, when restarting the pipe welding, the welding torch is moved in the traveling direction of the pipe body while the pipe body is stopped, and then the welding current is applied to the welding torch from a predetermined position to a predetermined position. Is supplied, the parts before and after the welding interruption part of the work are preheated. By returning the welding torch to the origin after the work is preheated, steady welding can be performed in the same state as when there was no temporary interruption in pipe welding.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing an embodiment of a pipe welding apparatus to which the pipe welding restarting method of the present invention is applied. The same members as those in the conventional example shown in FIG.

In the figure, reference numeral 1 is a tube for moving a tubular body 2 as a work, which is a cylindrically shaped metal tape in which the longitudinal direction and the central axis are parallel to each other, in the traveling direction (arrow A direction). The body moving means is composed of, for example, a plurality of rollers arranged so as to sandwich the tube body 2 and a motor for rotating each roller (not shown). Tube moving means 1
A ground brush 3 is provided on the lower side of the tube 2 delivered to the outlet side of the tube 2, and the tube 2 slides on the ground brush 3. A screw 9 is arranged by a support member (not shown) on the upper side of the tube body 2 on the outlet side of the tube body moving means 1 so as to be parallel to the tube body 2, and one end (the right end in the figure) of the screw 9 is connected to the motor 10. It is connected to the output shaft. A supporting member 11 of the welding torch 4 is engaged with the screw 9.
The distance h between the screw 9 and the pipe body 2 is set so that the electrode (for example, a tungsten electrode) 5 of the welding torch 4 approaches the boundary of the pipe body 2. The welding torch 4 can be moved in parallel along the pipe body 2 by the rotation of the screw 9 (for example, when the motor 10 rotates in the forward direction, it moves in the direction of arrow A, and when the motor 10 rotates in the reverse direction, the arrow). It moves in the opposite direction to A). The screw 9 and the motor 10 form a welding torch moving means 12.

Reference numeral 6 is a welding power source, and its output lines 13 and 1
4 are connected to the ground brush 3 and the electrode 5 of the welding torch 4, respectively.

Reference numeral 15 is a control means for controlling the movement and stop of the pipe 2 by the pipe moving means 1, the forward rotation, reverse rotation and stop of the motor 10 of the welding torch moving means 12 and the welding current of the welding power source 6. For example, a microcomputer is used. The microcomputer 15 uses the welding torch moving means 12 to set the origin P0 of the welding torch 4, a predetermined position (welding start point) P1 or a fixed position (welding stop point) P.
The arrival at 2 is managed by time.

To simplify the description, the welding rod supply system, the inert gas system and the cooling system are omitted.

Next, the operation of pipe welding by the present pipe welding apparatus will be described with reference to FIGS.

FIG. 2 is a flow chart showing the restart operation of the pipe welding apparatus shown in FIG. 1, and FIG. 3 is a diagram showing the positional relationship of the welding torches shown in FIG. FIG. 4 is a diagram showing the moving speed of the welding torch of the pipe welding apparatus shown in FIG. 1, where the horizontal axis is the time axis and the vertical axis is the torch moving speed axis. FIG. 5 is a diagram showing the welding current of the pipe welding apparatus shown in FIG. 1, where the horizontal axis is the time axis and the vertical axis is the welding current axis. However, the time axis of FIG. 4 and the time axis of FIG. 5 are common.

First, when the steady welding is started, the microcomputer 15 shown in FIG. 1 sets the welding torch 4 at the origin P0.
While being fixed to (FIG. 3 (a)), the tube body 2 is moved in the direction of arrow A at the work moving speed as shown in FIG.
A welding current as shown in FIG. 8 is supplied from the welding power source 6 to the welding torch 4. An arc is generated between the electrode 5 of the welding torch 4 and the tubular body 2, a filler wire (not shown) is supplied, the boundary of the tubular body 2 is welded, and the pipe 8 is formed (FIG. 2, step S-1). ).

It is assumed that pipe welding is temporarily interrupted for some reason. At this time, the movement of the tubular body 2 as the work is stopped, the supply of the welding current to the welding torch 4 is stopped, and the steady welding is stopped (FIG. 2, step S-2).

When the pipe welding is restarted in such a state, the microcomputer 15 causes the pipe moving means 1 to operate.
With the welding stopped, the motor 1 of the welding torch moving means 12
0 is rotated forward to move the welding torch 4 to the welding start point P1 (FIG. 2, step S-3). At this time, the welding torch 4 moves in the same direction (arrow B direction) as the traveling direction of the tube body 2 (arrow A direction) (FIG. 3B).

When the welding torch 4 reaches the welding start point P1, the microcomputer 15 detects this and supplies a constant welding current from the welding power source 6 to the welding torch 4 (step S-4 in FIG. 2). The welding torch 4 is moved to the welding stop point P2 by switching 10 from the normal rotation to the reverse rotation (FIG. 2, step S-5). At this time, the welding torch 4 moves to the welding stop point P2 via the origin P0 in the direction (arrow C) opposite to the traveling direction of the tubular body 2 (arrow A direction) (FIG. 3 (c)).

From FIGS. 7 and 8, it can be seen that a current for heating up the tubular body 2 flows for a certain period of time before the welding torch 4 starts moving. It can be seen that when the welding current increases and reaches a constant value, the welding torch 4 starts to move with a slight delay.

When the welding torch 4 passes through the origin P0 and reaches the welding stop point P2, the microcomputer 15 detects this and stops the supply of the welding current to the welding torch 4 and the motor 10 is slightly delayed. Stop rotation. In this state, the pipe is formed by welding the boundary of the pipe body from the origin to the right side (FIG. 2, step S-).
6).

The microcomputer 15 includes a motor 10
Is normally rotated to return the welding torch 4 to the origin P0 (FIG. 2, step S-7). At this time, the welding torch 4
Moves in the direction of arrow D, which is the same as the traveling direction of the tubular body 2 (FIG. 3).
(D)).

When the welding torch 4 returns to the origin P0, the microcomputer 15 operates the motor of the pipe moving means 1 while keeping the welding torch 4 fixed at the origin P0 and moves the pipe 2 in the traveling direction (arrow A). Direction),
A welding current is supplied from the welding power source 6 to the welding torch 4.
That is, steady welding is started again and the pipe 8 is formed (FIG. 2, step S-1). The position of the welding torch 4 at this time is as shown in FIG. 3 (e).

As described above, in the present embodiment, before restarting the pipe welding, the welding current is supplied to the welding torch 4 while the welding torch 4 moves back and forth around the pipe body 2 around the portion where the welding is interrupted. Therefore, before and after the welding interrupted portion of the tube body 2 is preheated (heated up). Therefore, even if the pipe welding is restarted, the same state as in the case where there is no temporary interruption of the welding is performed, and the steady welding can be performed.

In this embodiment, the screw 9 and the motor 10 are used to move the welding torch 4, but the present invention is not limited to this, and a linear motor, a cylinder or the like may be used. Further, in the present embodiment, the case where the pipe welding is restarted once has been described, but the present invention is not limited to this, and may be restarted any number of times. Further, although the case where the TIG welding method is used has been described in the present embodiment, the present invention is not limited to this and may be applied to the MIG welding method.

[0033]

In summary, according to the present invention, the following excellent effects are exhibited.

Before restarting the pipe welding, the welding torch moves back and forth around the portion where the welding is interrupted and the welding current is supplied to preheat the area before and after the interrupted portion of the work, so that the welding is temporarily stopped. The restart of pipe welding after interruption can be easily performed any number of times, and the welding state can be performed in the same manner as in the steady state.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a pipe welding apparatus to which a pipe welding restarting method of the present invention is applied.

FIG. 2 is a flowchart showing a restart operation of the pipe welding apparatus shown in FIG.

FIG. 3 is a diagram showing a positional relationship of welding torches of the pipe welding apparatus shown in FIG.

4 is a diagram showing a moving speed of a welding torch of the pipe welding apparatus shown in FIG.

5 is a diagram showing a welding current of the pipe welding apparatus shown in FIG.

FIG. 6 is a conceptual diagram of a pipe welding apparatus to which a conventional pipe welding method is applied.

7 is a diagram showing a work moving speed of the pipe welding apparatus shown in FIG.

8 is a diagram showing a welding current of the pipe welding apparatus shown in FIG.

[Explanation of symbols]

 1 tube moving means 2 tube 3 grounding brush 4 welding torch 6 welding power source 8 pipe 12 welding torch moving means 15 control means (microcomputer)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Yoshida 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Yoshinobu Sato 5 Hidaka-cho, Hitachi City, Ibaraki Prefecture 1-1-1 Hitachi Cable Co., Ltd. Hidaka Factory

Claims (3)

[Claims] 1. A pipe body formed by molding a metal tape into a cylindrical shape is moved along the longitudinal direction while welding the boundary of the pipe body to form a pipe, and then the welding is temporarily suspended and then the pipe welding is performed again. In the method of restarting pipe welding, the welding torch is moved from the origin in the traveling direction of the pipe while the pipe is stopped, and when the welding torch reaches a predetermined position, the welding torch is moved in the opposite direction and welding is performed. Welding current is supplied to the torch, and when the welding current reaches a position a certain distance from the origin, the welding current is stopped and then the welding torch is returned to the origin and the welding torch is welded while moving the pipe body in the traveling direction. A method for restarting pipe welding, characterized by supplying an electric current. 2. A pipe moving means for moving a pipe formed by molding a metal tape into a cylindrical shape along a longitudinal direction, a welding torch for welding a boundary between the pipes to form a pipe, and the welding torch. Power source for supplying a welding current, a welding torch moving means for moving the welding torch along the longitudinal direction of the pipe body, and the pipe body being stopped when the pipe welding is restarted after being suspended. , Move the welding torch from the origin in the traveling direction of the pipe, and when the welding torch reaches a predetermined position, move the welding torch in the opposite direction and supply the welding current to the welding torch at a position apart from the origin by a certain distance. When the welding current is stopped, the welding torch is returned to the origin, and a control means for supplying the welding current to the welding torch while moving the pipe body in the traveling direction is provided. Ip welding equipment. 3. The pipe welding apparatus according to claim 2, wherein a screw engaged with the welding torch and a motor for rotating the screw are used to move the welding torch.