JP2003019557A - Welding method and welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of welded strain when piping, etc., is welded. SOLUTION: A traveling part 2 is fitted to the welding portion in the piping 1, and a plurality of welding heads 3 are fitted to this part in a prescribed interval. Then, the respective welding heads 3 are simultaneously shifted as the prescribed interval with a control signal from a control unit, and the generation of the welded strain is prevented by uniformly diffusing the welded heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method which does not generate welding strain due to heat and a welding apparatus for carrying out the welding method.

[0002]

2. Description of the Related Art High-pressure piping and piping in nuclear facilities are often connected by highly reliable welding. When welding such pipes by, for example, arc welding,
When the welding head is moved along the welding line of the pipe, those welding parts are heated by the welding heat (arc heat) and thermally expand, and after passing through the welding head, are naturally cooled and contracted again. Such a concentrated thermal expansion portion moves together with the welding head, but after cooling, internal stress caused by thermal expansion with other portions generally remains in the pipe as welding strain.
Such welding distortion is not preferable because it significantly reduces product value and reliability.

Conventionally, such welding distortion cannot be avoided, and a method of removing it after welding has been generally used. As a method for removing welding distortion, for example, a mechanical distortion removing method by pressing, straightening roller, hammering, etc., a thermal distortion removing method by local heating using a heat source such as oxygen gas flame, plasma, or a combination thereof and so on.

[0004]

However, whichever method of removing the welding distortion is adopted, it is unavoidable that it takes time and labor to increase the cost. Therefore, the present invention aims to prevent the occurrence of strain during such welding, thereby omitting the strain removal step after welding, a new welding method therefor, and a welding apparatus for carrying out the method. The purpose is to provide.

[0005]

According to a first aspect of the present invention for solving the above-mentioned problems, in a method for welding by moving a welding head along a welding line of an object to be welded, a welding strain is applied to the object to be welded. A plurality of welding heads are spaced apart from each other so as not to be generated, and are synchronously moved along the welding line to perform welding. (Claim 1)

In the above welding method, the plurality of welding heads can be synchronously moved and controlled by the control means.
(Claim 2) In any one of the above welding methods, when at least one of the plurality of welding heads malfunctions, the remaining welding heads can perform welding. (Claim 3)

A second aspect of the present invention which solves the above-mentioned problems is a welding apparatus in which a welding head is moved along a welding line of an object to be welded to perform welding. It is characterized by comprising a traveling unit for moving the welding heads along the welding line, and a control means for synchronously controlling the movement of each welding head along the traveling unit. (Claim 4)

In the above welding apparatus, the control means includes a plurality of control units provided for each welding head, and a general control unit for integrally controlling the control units so that the respective welding heads are synchronously moved and controlled. You can (Claim 5) And, in the above welding apparatus, the integrated control unit has a personal computer having a communication port,
The communication port of the personal computer and the communication port provided in each control unit can be connected via a switching interface. (Claim 6)

A third invention according to the present invention for solving the above-mentioned problems is a welding apparatus in which a welding head is moved along a welding line of an object to be welded to perform welding, and a plurality of welding heads and those weldings are performed. It is characterized in that a running part for moving the head along the welding line, a connecting body for connecting a plurality of welding heads at a predetermined interval, and a common driving part are provided. (Claim 7)

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view showing a basic form of a welding device according to the first embodiment. In the figure, 1 is a pipe, 2 is a running part, 3 is a plurality of (three in this example) welding heads, 4 is a welding torch, and 5 is a welding wire. 2 is a schematic explanatory view showing a drive unit and a control means for driving one welding head 3 in FIG. 6 in the figure
Is a drive unit, 7 is a power supply unit, 8 is control means, 9 is a control unit, 1
Reference numeral 0 is a camera such as a CCD image pickup device.

In these drawings, the welded portion of the pipe 1 is fixed to a support device (not shown), and the running portion 2 formed in an annular shape is fixed and positioned on the support device. A gear portion is formed on the outer peripheral surface of the traveling portion 2, and the gear portion and the gear portions provided on the three welding heads 3 mesh with each other. Then, each welding head 3 is controlled by the drive unit 6 to move along the outer peripheral surface of the traveling unit 2 at a set speed.

A welding torch 4 provided on each welding head 3.
A welding wire 5 is supplied at a predetermined speed to a tip portion of the welding wire by a wire supply device (not shown), and a welding power source 7 supplies a welding power to the welding torch 4. The wire supply device, the power supply unit 7 and the drive unit 6 are controlled by the control unit 9 as the control unit 8. That is, the control unit 8 controls the drive unit 6 so that the welding head 3 moves along the traveling unit 2 at a preset speed (welding speed) so that the supply of the welding wire 5 is adapted to the welding speed. The wire supply device is controlled, and the power supply unit 7 is controlled so that the necessary welding power supply is supplied.

In this example, as an example, three welding heads 3 arranged at equal intervals of 120 degrees in the circumferential direction are moved along the traveling portion 2 in the same direction at the same speed to perform welding,
The welding heat can be dispersed at equal intervals along the welded portion of the pipe 1. By thus dispersing the welding heat at equal intervals, it is possible to avoid local concentration of thermal expansion due to the welding heat, and as a result, it is possible to effectively prevent the thermal distortion of the pipe 1. In order to move each welding head 3 synchronously in this way, for example, the same speed is set in the speed setting unit in each control unit 9, and a control signal is generated so that each welding head 3 moves at the set speed. Is output.

The camera 10 monitors the welding state and transmits it to the control unit 9. The control unit 9 receives the signal and controls, for example, the power supply unit 7 so that the welding state is optimized. These control units 9 are composed of a microcomputer and a sequencer, and speed setting and the like can be performed by a program.

FIG. 3 is a schematic explanatory view of a welding apparatus according to the second embodiment of the present invention. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals. In this example, three welding heads 3 are provided as in FIG. 1, but they are shown in a linear arrangement in order to simplify the drawing.

Each welding head 3 can be moved by a drive unit 6 at a set speed along the outer peripheral surface of the running unit 2 (not shown). The welding wire 5 is supplied to the tip of the welding torch 4 provided on the welding head 3 at a predetermined speed by a wire supply device (not shown), and the welding torch 4 is supplied with welding power from the power supply 7. The wire supply device, the power supply unit 7 and the drive unit 6 are controlled by the control means 8.

The control means 8 is composed of a control unit 9 provided in each welding head 3 and a general control unit 11 for integrally controlling these three control units 9. The integrated control unit 11 is a CPU
It has a personal computer 12 including a (central processing unit) and a display unit 13 such as a display, and further includes an input unit such as a keyboard and a mouse (not shown) and an output unit such as a printer. The personal computer 12 is provided with three communication ports (not shown), and these communication ports are connected to the communication ports (not shown) of the control unit 9 for controlling each welding head 3 via the communication lines N, respectively. To be done.

The personal computer 12 is provided with a switching means for sequentially switching (scanning) three communication ports,
The three welding heads 3 are sequentially controlled by so-called time sharing. Then, the control unit 9 of the welding head 3 receives a control signal from the personal computer 12 during the period connected to the personal computer 12 to control the drive unit 6 and the like, and as a result, the positional information of the welding head 3 and the welding power source information. Etc. are transmitted to the personal computer 12. Then, the personal computer 12 centrally controls the welding heads 3 so that the welding heads 3 move in a synchronous manner while maintaining the predetermined intervals.

A communication retry control, a communication record creating function and the like can be added to the central control unit 11 by a program. The communication retry control is control for repeating communication when a communication error occurs between the personal computer 12 and each control unit 9. Generally, when a control signal is output from the personal computer 12 to the control unit 9, the control unit 9 which receives the control signal performs control according to the control signal, and the result is fed back to the personal computer 12. Since there is a predetermined time delay, the waiting time is set in the personal computer 12. However, this time may vary depending on the state of the communication circuit, which may cause the reception error in the personal computer 12. In such a case, the communication retry control works effectively.

To explain the communication function, the present welding apparatus can send and receive communication signals every 100 msec (milliseconds), but if all of them are recorded, a huge storage capacity is required. Therefore, a communication record creating function is provided so that main records of the system, for example, a record of a control signal to the control unit 9 and a record when the retry control is generated are stored in a memory or the like and can be stored in the output unit at any time. Make it accessible.

FIG. 4 is a flow chart showing the control sequence in FIG. 3. In the figure, the right side across the communication line N shows the operation of the integrated control section 11, and the left side shows the operation of each control section 9 for it. Each control unit 9 starts when the power is turned on,
The origin of the head shaft in the welding head 3 to be controlled is detected by a position detecting means (not shown), and then the head shaft is moved to a predetermined position.

When a start signal is given to the general control section 11, the welding program is started (step S1). First, in step S2 (hereinafter, simply abbreviated as S2), the position of the head axis is confirmed with respect to the control unit 9. In S3, the head axis position data is sent from each control unit 9, and in S4, the overall control unit 11
Recognizes it. Next, in S5, the overall control unit 11 selects the welding conditions of each welding head from a large number of welding conditions including the pre-stored welding operation procedure, and in S6, sends them to each control unit 9 for each control. The part 9 recognizes the welding conditions in S7.

Next, in S8, the integrated control unit 11 instructs the welding line scanning numerical value to each welding unit 9, and each control unit 9 feeds back the position data of the head axis from the position detector to the integrated control unit 11 in S9. To do. This instruction and feedback are repeated in a very short period during the welding operation. Next, in S10, the integrated control unit 11 instructs each control unit 9 to move to the welding start point, and in S11, each control unit 9 controls the drive unit 6 to drive each welding head 3 to move its head axis. Is moved to the welding start point, and the movement position data is fed back to the overall control unit 11. This completes the preparation for starting welding.

Next, in step S12, the integrated control unit 11 causes each control unit 9
To start welding, and in response to this, in S13, each control unit 9
Starts welding control. When welding is started, in S14, the overall control unit 11 causes each control unit 9 to maintain the welding conditions and head axis based on the welding state data of each welding head 3 by the camera 10 and the position data of the head axis. A position correction instruction is issued at any time, and in response to this, each control unit 9 performs these corrections and feeds back the corrected welding condition data and head axis position data to the overall control unit 11.

When the integrated control unit 11 confirms that the welding is completed in S16, the welding program ends and the display unit 1
No. 3 is notified of the end of welding, or the next welding operation is started. As described above, when communication retry control is added to the integrated control unit 11 by a program and a communication error occurs with each control unit 9, for example, communication is repeated up to three times and communication is still not normal. Stops the welding operation and informs the display unit 13 or the like to that effect.

FIG. 5 is a schematic explanatory view of a welding apparatus according to the third embodiment of the present invention. The same parts as those in FIG. 3 are designated by the same reference numerals. In this example, the overall control unit 11 constituting the control means 8 has a personal computer 12 having a communication port, and the communication port of the personal computer 12 and the communication port provided in each control unit 9 are connected via a switching interface 14. There is.

The switching interface 14 as described above is
This is effective when the personal computer 12 does not have a plurality of communication ports and switching means for switching them, as in the example of FIG.
In this example, a program for driving the switching interface 14 is stored in the personal computer 12, and communication is sequentially switched between the personal computer 12 and the three control units 9 according to the program to control the three welding heads 3. Movement is controlled along the traveling unit 2 synchronously at intervals. The welding operation is performed in the same sequence as in FIG.

FIG. 6 is a schematic explanatory view of a welding apparatus according to the fourth embodiment of the present invention, and the same parts as those in FIG. 5 are designated by the same reference numerals. In this example, three welding heads 3
Only one of them has a common drive unit 6, and the other welding heads 3 have no drive unit 6.

FIG. 7 is a schematic explanatory view of a state where the three driving heads 3 are synchronously moved by the common driving unit 6 in FIG. The three welding heads 3 move along the running part 2 and they are connected to each other by an arcuate connecting body 15.
It is connected at intervals of degrees. The common driving unit 6 allows the three welding heads to rotate synchronously while maintaining the distance therebetween. According to the method of achieving synchronization mechanically in this way, the structure of the welding device is simplified, and the size can be reduced. The welding operation in this case is performed in the sequence according to FIG.

FIG. 8 is a schematic explanatory view of a welding apparatus according to the fifth embodiment of the present invention, and the same parts as those in FIG. 5 are designated by the same reference numerals. In this example, the control means 8 changes the control method for an abnormal situation. For example, if the welding head 3 at the right end of FIG.
It is controlled to perform welding by the base welding head 3.
Specifically, when a code such as the number of the defective welding head 3 is input from the input section of the personal computer 12 constituting the control means 8, the fault control program stored in the personal computer 12 in advance is switched.

That is, a command is issued to the switching interface 14 to disconnect the signal transmission / reception circuit with the control unit 9 of the welding head 3 excluded as a failure, and the control unit 9 of the remaining sound welding head 3 is integrated. Take control. In that case, since uniform welding control is not performed over the entire circumference of the pipe, some welding distortion is unavoidable. However, since this control is an emergency control that is performed only for a very short time when an abnormal situation continues, it is performed based on the idea that some disadvantage can be tolerated.

FIG. 9 shows the head axis position information of each welding head 3 displayed on the display unit 13, the welding information, the remote controller (driving unit 6 and the like), etc. The welding conditions and the like can be changed as necessary.

[0033]

As described above, the welding method according to the first aspect of the present invention is characterized in that a plurality of welding heads are spaced apart from each other and are moved synchronously along the welding line for welding. Therefore, it is possible to effectively prevent the generation of welding distortion in the welding target.

Further, the welding apparatus according to the present invention controls a plurality of welding heads, a traveling section for moving the welding heads along the welding line, and synchronously moving each welding head along the traveling section. It is characterized in that it is provided with a control means for controlling. By using this welding device, it is possible to effectively prevent the generation of welding distortion in the welding target. Further, since the welding conditions and the like can be selected and set by the control means, it is easy to apply to various welding.

Further, another welding apparatus according to the present invention comprises a plurality of welding heads, a running portion for moving the welding heads along the welding line, and a connecting body for connecting the plurality of welding heads at predetermined intervals. A common drive unit is provided. By using this welding device, it is possible to effectively prevent the generation of welding distortion in the welding target. Further, the device configuration is simplified and the device can be made compact.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a basic form of a welding device according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a drive unit and control means for driving one welding head 3 in FIG.

FIG. 3 is a schematic explanatory view of a welding device according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a control sequence in FIG.

FIG. 5 is a schematic explanatory view of a welding device according to a third embodiment of the present invention.

FIG. 6 is a schematic explanatory view of a welding device according to a fourth embodiment of the present invention.

7 is a schematic explanatory view of a state in which three welding heads 3 are synchronously moved by a common drive unit 6 in FIG.

FIG. 8 is a schematic explanatory view of a welding device according to a fifth embodiment of the present invention.

9 is a diagram showing a display example of a display unit 13 in FIG.

[Explanation of symbols]

1 piping 2 running section 3 welding head 4 welding torch 5 welding wire 6 drive 7 power supply 8 Control means 9 control unit 10 cameras 11 Integrated control section 12 PC 13 Display 14 Switching interface 15 Connected body N communication line

Claims (7)

[Claims] 1. A method of welding by moving a welding head along a welding line of an object to be welded, wherein a plurality of welding heads 3 are spaced apart from each other so as not to generate welding distortion in the object to be welded. Welding method characterized in that the welding is performed by synchronously moving along the line. 2. The welding method according to claim 1, wherein the plurality of welding heads 3 are synchronously moved and controlled by the control means 8. 3. The welding method according to claim 1, wherein when at least one of the plurality of welding heads 3 malfunctions, the remaining welding heads 3 perform welding. 4. In a welding device in which a welding head is moved along a welding line of an object to be welded for welding, a plurality of welding heads 3 and for moving the welding heads 3 along the welding line. Running part 2 and each welding head 3
A welding device, comprising: a control means 8 for synchronously controlling the movement of the vehicle along the traveling portion 2. 5. The control means 8 includes a plurality of control units 9 provided for each welding head 3, and a general control unit 11 for integrally controlling the control units 9 so that the respective welding heads 3 are synchronously moved and controlled. The welding apparatus according to claim 4, further comprising: 6. The integrated control unit 11 has a personal computer 12 having a communication port, and the communication port of the personal computer 12 and the communication port provided in each control unit 9 are switching interfaces 14.
The welding device according to claim 5, wherein the welding device is connected via the. 7. A welding device in which a welding head is moved along a welding line of an object to be welded for welding, and a plurality of welding heads 3 and for moving the welding heads 3 along the welding line. 2. A welding device, comprising: the running unit 2 of FIG. 1, a connecting body 15 that connects a plurality of welding heads 3 at predetermined intervals, and a common driving unit 6.