Control Device, Control Method, and Program

Abstract

To provide a control device, a control method, and a program that enable stable welding.SOLUTION: Provided is a control device that controls a welding or fusion device that performs welding or fusion along a peripheral direction of a piping. The control device controls the welding or fusion device to perform welding or fusion by changing a welding or fusion condition while axially rotating the piping. The welding is keyhole welding.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device, a control method, and a program.

Background Art

[0002] In a circumferential automatic TIG welding apparatus for a fixed pipe, full penetration welding is performed to form a back bead using a heat conduction type non-keyhole. The postures of the welding torch include downward, downhand, vertical, uphill, and all positions, and optimal welding conditions are required for each posture. Therefore, the circumference of the fixed pipe is divided into four or eight parts, and stable back beads are ensured by controlling the welding conditions individually.

[0003] In a circumferential automatic TIG welding apparatus for a rotating pipe, the torch position is fixed. The posture of the welding torch is downward and is not controlled in a divided manner.

[0004] Patent Documents 1 and 2 disclose welding a rotating pipe using keyhole TIG welding.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When welding a horizontal rotating pipe using keyhole TIG welding, in order to maintain the keyhole, an arc force in a high welding current region, a high-speed rotation adapted to the high welding current, and adjustment of welding conditions for each welding area are required. The circumferential automatic TIG welding apparatus for a rotating pipe disclosed in Patent Document 1 performs control under fixed welding conditions, with the rotation direction being horizontal and the torch position being downward and advancing. Therefore, the melted molten pool leads the way, making it impossible to maintain the shape and size of the keyhole, resulting in the keyhole being blocked and the back bead not being formed, and it is impossible to ensure stable back beads in the lap portion and crater portion. In the plasma welding method disclosed in Patent Document 2, the rotation direction is vertical, the torch position is downward, and since the welding current is as low as 150 A, the molten pool does not lead the way, and there is no need to increase the rotation speed. An object of the present invention is to provide a control device, a control method, and a program that enable stable welding.

Means for Solving the Problems

[0007] One aspect of the present invention is a control device for controlling a welding or cutting device that performs welding or cutting along the circumferential direction of a pipe, the control device controlling the welding or cutting device to perform welding or cutting while changing welding or cutting conditions while rotating the pipe around its axis.

Effects of the Invention

[0008] According to the present invention, stable welding can be enabled.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the configuration of a pipe automatic welding system 100 according to an embodiment of the present invention. The automatic welding system 100 includes a pipe automatic welding apparatus 1 and a control apparatus 20. The control apparatus 20 controls the pipe automatic welding apparatus 1 to perform welding of the pipe P.

[0012] In the drawings shown below, an XYZ orthogonal coordinate system is set, and the X-axis direction is the front-rear direction (width direction) of the automatic welding apparatus 1 along the circumferential direction of the pipe P, the Y-axis direction is the left-right direction (depth direction) of the automatic welding apparatus 1 along the axial direction of the pipe P, and the Z-axis direction is the up-down direction (height direction) of the automatic welding apparatus 1, and each is shown accordingly.

[0013] As shown in FIG. 1, the automatic welding apparatus 1 of the present embodiment automatically performs welding along the circumferential direction of the pipe P while rotating the pipe P about its axis.

[0014] Specifically, this automatic welding apparatus 1 includes a welding head 2 that is positioned on the outer peripheral surface of the pipe P and performs welding on the pipe P that rotates about its axis, and a head support mechanism 3 that supports the welding head 2 so as to be movable in the up-down direction and the front-rear direction along the circumferential direction of the pipe P. The head support mechanism 3 is attached to the frame (not shown) of this automatic welding apparatus 1.

[0015] The welding head 2 is, for example, a generally used TIG welding torch (non-consumable welding torch). The welding head 2 has a non-consumable electrode 4 that generates an arc current with the pipe P, and a torch nozzle 5 that discharges a shielding gas toward the molten pool generated by the arc.

[0016] FIG. 2 is a diagram for explaining the position of the welding head 2. It is desirable that the welding head 2 be in the position from 0:30 to 2:30 with respect to the pipe P. When explained using the XYZ orthogonal coordinate system, as shown in FIG. 2, when the pipe P rotates counterclockwise when viewed in the positive direction along the Y-axis, it is desirable that the welding head 2 be in the region of (X, Z) = (-cosθ, sinθ) (15° ≤ θ ≤ 75°). When the welding head 2 is in the 0:00 position, that is, (X, Z) = (0, 1), a convex bead is generated and the molten pool is likely to drip to the side opposite to the traveling direction. By setting the position of the welding head 2 in the region shown in FIG. 2, it is possible to prevent the generation of a convex bead and the dripping of the molten pool to the side opposite to the traveling direction.

[0017] A wire aiming guide 6 is attached to the welding head 2. The wire aiming guide 6 has a feeding head 6a that feeds out the filler wire W from its tip side while guiding the filler wire W, and a liner (also called a conduit) 6b that feeds the filler wire W toward the tip of the feeding head 6a.

[0018] The feeding head 6a has a nozzle shape whose tip side extends toward the tip side of the non-consumable electrode 4. Further, the wire aiming guide 6 has a rotation mechanism 6c that rotatably supports the feeding head 6a, making it possible to adjust the angle of the feeding head 6a. The liner 6b is connected to a wire feeding device (not shown), and the filler wire W can be automatically fed by this wire feeding device.

[0019] The wire aiming guide 6 is attached to the front side of the welding head 2 via a guide support mechanism 7. The guide support mechanism 7 has a height adjustment part 7a that adjusts the vertical (Z-axis direction) position of the wire aiming guide 6 with respect to the welding head 2, and a depth adjustment part 7b that adjusts the horizontal (Y-axis direction) position of the wire aiming guide 6 with respect to the welding head 2.

[0020] In the guide support mechanism 7, after adjusting the vertical and horizontal positions of the wire aiming guide 6 with respect to the welding head 2 by the height adjustment section 7a and the depth adjustment section 7b, it is possible to fix the positions.

[0021] Further, an after - shield mechanism 8 is attached to the welding head 2. The after - shield mechanism 8 has an after - shield cover 8a that covers the rear side in the welding line direction from the tip side of the welding head 2, and releases after - shield gas to the weld bead formed immediately after welding of the pipe P from the inside of this after - shield cover 8a.

[0022] The head support mechanism 3 includes an up - down slider 3a that supports the welding head 2 so as to be movable in the vertical direction (Z - axis direction) with respect to the pipe P, a front - rear slider 3b that supports the welding head 2 so as to be movable in the front - rear direction (X - direction) with respect to the pipe P, a height adjustment section 3c that adjusts the vertical position (X - axis direction) of the welding head 2 with respect to the pipe P, and a depth adjustment section 3d that adjusts the horizontal position (Y - axis direction) of the welding head 2 with respect to the pipe P.

[0023] In the head support mechanism 3, the up - down slider 3a and the front - rear slider 3b can always move the welding head 2 in the vertical and front - rear directions with respect to the pipe P. In the head support mechanism 3, after adjusting the vertical and horizontal positions of the welding head 2 with respect to the pipe P by the height adjustment section 3c and the depth adjustment section 3d, it is possible to fix the positions.

[0024] The head support mechanism 3 has a pair of rotating rollers 9 arranged in the circumferential direction of the pipe P. The pair of rotating rollers 9 are attached to the lower end portion of the up - down slider 3a via a mounting plate 10 so as to keep the distance between the outer peripheral surface of the pipe P and the tip of the welding head 2 constant.

[0025] A pair of rotating rollers 9 is pivotally supported by a mounting plate 10 so as to be capable of rotating while being in sliding contact with the outer peripheral surface of the pipe P. Further, the pair of rotating rollers 9 is pressed against the outer peripheral surface of the pipe P by the weight of the welding head 2.

[0026] Further, the head support mechanism 3 has an offset adjustment portion 11 for adjusting the position (offset) in the front-rear direction of the welding head 2 with respect to the uppermost part of the pipe P. The offset adjustment portion 11 can change the mounting position in the front-rear direction of the mounting plate 10 with respect to the lower end portion of the vertical slider 3a.

[0027] In the head support mechanism 3, after adjusting the position in the front-rear direction of the welding head 2 with respect to the uppermost part of the pipe P by this offset adjustment portion 11, it is possible to fix that position.

[0028] Hereinafter, a control method of the automatic welding apparatus 1 by the control device 20 will be described. The control device 20 controls the magnitude of the arc current generated by the non-consumable electrode 4. The control device 20 controls the rotating roller 9 to rotate the pipe P about its axis while changing the welding conditions, and causes the welding head 2 to perform welding along the circumferential direction of the pipe P. The control device 20 may change the welding conditions while the rotating roller 9 rotates the pipe P once, or may change the welding conditions every time the pipe P rotates once. However, from the point of preventing the melted molten pool from dripping, it is preferable to change the welding conditions while the pipe P makes one revolution.

[0029] The welding conditions are at least one of the wire feeding speed by the wire aiming guide 6, the rotation speed of the pipe P due to the rotation of the rotating roller 9, and the type of arc current generated by the non-consumable electrode 4. The control device 20 individually sets the wire feeding speed, the rotation speed of the pipe P, and the type of arc current.

[0030] The control device 20 changes the welding conditions according to, for example, the rotational speed or rotational angle of the rotary roller 9. By changing the welding conditions according to the rotational speed or rotational angle of the rotary roller 9, the control device 20 can change the welding conditions according to the rotational speed of the pipe P. The control device 20 controls the heat input by individually setting the wire feeding speed and the magnitude of the arc current according to the rotational speed of the pipe P, and can suppress the occurrence of melting and internal defects during the lap crater treatment during the welding. When the rotational speed of the pipe P slows down, for example, the control device 20 can make the excess bead height the same by slowing down the wire feeding speed. Also, when the rotational speed of the pipe P increases, for example, the control device 20 can make the excess bead height the same by increasing the wire feeding speed.

[0031] The rotational speed of the pipe P is preferably 40 cm / min or more and 150 cm / min or less. More preferably, the rotational speed of the pipe P is 50 cm / min or more and 100 cm / min or less.

[0032] Also, the control device 20 can change the welding conditions for each welded region of the pipe P by changing the welding conditions according to the rotational speed or rotational angle of the rotary roller 9. For example, as shown in FIG. 3, the control device 20 can divide the welded region of the pipe P into regions A1 to A4 and change the welding conditions for each region.

[0033] The type of arc current is at least one of an initial current, an upslope current, a main welding current, a downslope current, and a crater current. FIG. 4 is a diagram showing the change in the type of arc current. In FIG. 4, the vertical axis represents the magnitude of the arc current, and the horizontal axis represents time. The control device 20 changes the arc current in the order of the initial current, the upslope current, the main welding current, the downslope current, and the crater current.

[0034] The initial current and the upslope current are the starting currents for reaching the present welding current. The present welding current is the arc current during welding. The downslope current and the crater current are the currents for shutdown after welding is completed. When the pipe P is a carbon steel pipe, by performing shutdown with a downslope current in which the magnitude of the current gradually decreases after rotation is stopped, it is possible to prevent blowholes from occurring in the final crater treatment.

[0035] The control device 20 may change the magnitude of the present welding current. The magnitude of the present welding current is preferably 350 A or more and 1000 A or less. Further, the magnitude of the present welding current is more preferably 400 A or more and 800 A or less.

[0036] <Other Embodiments> As described above, one embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of the present invention. In the above embodiment, the case where TIG welding is automatically performed along the circumferential direction of the pipe P while rotating the pipe P around its axis is illustrated. However, the welding method is not limited to non-consumable electrode type gas shielded arc welding such as TIG welding, and may be consumable electrode type gas shielded arc welding such as MIG welding, MAG welding, or carbon dioxide gas arc welding.

[0037] Also, in the above embodiment, the case where the present invention is applied to an automatic pipe welding apparatus that automatically performs welding along the circumferential direction of the pipe by a welding head while rotating the pipe around its axis is described. However, it is also possible to apply the present invention to an automatic pipe cutting apparatus that automatically performs cutting along the circumferential direction of the pipe by a cutting head while rotating the pipe around its axis.

[0038] Also, the plasma arc is not limited to the welding applications described above, and is also used, for example, for brazing, joining, cutting, spraying, and melting furnaces for workpieces. In the present invention, such applications other than welding are also treated as one form of welding.

[0039] All or part of the functions of the control device 20 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize it. Here, the "computer system" shall include the OS and the hardware of peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, etc., and a recording device such as a hard disk incorporated in a computer system. Furthermore, the "computer-readable recording medium" also includes a communication line such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, which dynamically holds the program for a short time, and a volatile memory inside a computer system that becomes a server or a client in that case, which holds the program for a certain period of time. Also, the above program may be for realizing a part of the above-described functions, and may further be realizable in combination with a program already recorded in the computer system for realizing the above-described functions. Also, all or part of the functions of the control device 20 may be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

Explanation of Reference Numerals

[0040] 1... Automatic welding apparatus 2... Welding head (TIG welding torch) 3... Head support mechanism 6... Wire aiming guide 7... Guide support mechanism 8... Aftershield mechanism 9... Rotating roller 10... Mounting plate 11... Offset adjustment section 100... Automatic welding system 20... Control device A... Region P... Pipe C... Central axis S... Rotation axis

Claims

1. A control device for controlling a welding or cutting device that performs welding or cutting along the circumferential direction of a pipe, controlling the welding or cutting device to perform welding or cutting while changing welding or cutting conditions while rotating the pipe around its axis, wherein the welding or cutting conditions are at least one of the wire feeding speed in welding or cutting, the rotation speed of the pipe, and the type of arc current, changing the welding or cutting conditions for each region of the pipe to be welded or cut, and changing at least one of changing the wire feeding speed, increasing and decreasing the rotation speed of the pipe, and increasing and decreasing the magnitude of the arc current, wherein the rotation speed of the pipe is 40 cm / min or more and 150 cm / min or less, wherein the magnitude of the arc current is 350 A or more and 1000 A or less, wherein the welding is keyhole welding, A control device.

2. The welding or cutting has a lap crater treatment after one revolution of the pipe, The control device according to claim 1.

3. When the pipe is rotated counterclockwise when viewed in the positive direction along the Y-axis, the position of the welding head used for the welding is in the region of (X, Z) = (-cosθ, sinθ) (15° ≤ θ ≤ 75°), The control device according to claim 1 or 2.

4. Changing the welding conditions during the actual welding in the welding, The control device according to claim 1 or 2.

5. A control method for controlling a welding or cutting device that performs welding or cutting along the circumferential direction of a pipe, controlling the welding or cutting device to perform welding or cutting while changing welding or cutting conditions while rotating the pipe around its axis, wherein the welding or cutting conditions are at least one of the wire feeding speed in welding or cutting, the rotation speed of the pipe, and the type of arc current, changing the welding or cutting conditions for each region of the pipe to be welded or cut, and changing at least one of changing the wire feeding speed, increasing and decreasing the rotation speed of the pipe, and increasing and decreasing the magnitude of the arc current, wherein the rotation speed of the pipe is 40 cm / min or more and 150 cm / min or less, wherein the magnitude of the arc current is 350 A or more and 1000 A or less, wherein the welding is keyhole welding, A control method.

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