JPH0811298B2 - Swing arc welding method and swing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic arc welding method for controlling groove profiling by controlling oscillating of a welding arc by utilizing an arc phenomenon, and in particular, oscillating arc. The present invention relates to a welding method and an oscillating device for automatic arc welding.

(Prior Art) In automatic welding, it is necessary to always hold the welding line and the welding torch in a fixed positional relationship with high precision, and various welding line tracing control methods have been conventionally proposed. As a method that does not require a special detector, various groove tracking control methods have been proposed in which an arc is oscillated in combination with an oscillating device to utilize the arc phenomenon.

Generally, as a swinging mechanism, for weaving welding in Volume 6 of "Welding and Welding Equipment" (P148-150), a method of swinging a crankshaft and swinging a welding torch around a fulcrum by a link mechanism is typical. Is widely known as a dynamic mechanism.

A method utilizing the welding arc phenomenon is disclosed in
In JP 58-176076, the welding torch is reciprocated in parallel with the width direction of the welding advancing direction so that the difference between the detection signal at the center of the swing and the detection signal at the end of the swing matches the reference value. A swing width control method for controlling has been proposed. In Japanese Patent Publication No. 57-3462, the welding torch is moved up and down to keep the arc voltage constant, and the distance from the base metal surface is changed.
The welding torch is reciprocated in parallel to the width direction of the welding advancing direction, and the reciprocating motion in the width direction is changed every time the vertical displacement height of the welding torch becomes equal to a predetermined set value. Motion is proposed.

However, the change in the welding current or the welding voltage to be detected here is generally considered to fluctuate due to the change in the distance between the tip and the base metal.
As shown in the figure, in the process in which the tip of the welding wire approaches the groove wall 28 on the right or left, that is, in the process of shortening the distance between the tip and the base metal, the change in wire protrusion length is delayed with respect to the change in arc length. The arc length becomes short, the welding current becomes large, and the welding voltage becomes low. Further, in the process of reversing the swing at both ends of the swing and moving away from the groove wall 28 on the right or left as shown in FIG. 4, that is, in the process of increasing the distance between the tip and the base metal, the arc length is lengthened and the welding is reversed. Since the current is small and the welding voltage is high, the welding current near both ends of the swing changes as shown in FIG. 5 and the welding voltage as shown in FIG. Therefore, the welding current and welding voltage when swinging the arc in the groove are as shown in FIG.

Utilizing this phenomenon, the inventors of the present invention have proposed a groove tracking control method in Japanese Patent Application No. 60-249958 by detecting the areas L and R of the figure drawn by the welding current and the swing position in FIG. Proposed. However, the changes in the welding current and the welding voltage in the vicinity of both ends of the swing as described above are caused not only by the change in the distance between the tip and the base metal but also by the change speed of the distance between the tip and the base metal. The changing speed of the distance between the tip and the base material near both ends of the movement is affected by the moving speed in the swing direction. That is, the amount of change in the welding current and welding voltage increases the swing width under a constant swing cycle or increases the number of swings under a constant swing width to increase the moving speed in the swing width direction. When is increased, it increases as shown in FIG. Therefore, in particular, in the groove width copying control in which the groove width is detected and the groove width is made to follow the groove width by the change amount of the welding current or the welding voltage at both ends of the rocking movement, as shown in FIG. The width becomes narrower than the optimum value, resulting in defective fusion at the groove corner.

Conversely, if the moving speed in the swing width direction is slowed down, the amounts of change in welding current and welding voltage decrease as shown in Fig. 10, so the swing width becomes wider than the optimum value as shown in Fig. 11, and the arc Due to this, the groove wall surface is dug, and an undercut is generated in the groove wall surface, which causes defective fusion and slag inclusion defects in the next pass.

Therefore, especially in automatic welding using welding line tracing control that detects the welding current or the welding voltage change near both ends of the swing and corrects the swing center position and swing width one by one according to the result,
It is necessary to keep the swing speed in the swing direction constant so that the detection result is not affected by fluctuations in the moving speed in the swing direction due to changes in the swing width and the number of swings.

However, no consideration is given to the influence of the swing on the fluctuation of the welding current and the welding voltage in any of the above methods, and the swing width and the number of swings are changed in any of the above swing methods. Has the drawback that the moving speed for changing the swing width must be changed, and the swing condition cannot be freely selected. Therefore, particularly in automatic welding using welding line tracing control that detects a welding current or welding voltage change near both ends of swing, it is difficult to perform stable and highly accurate groove line tracing by the conventional swing method, and There is a problem that it is not possible to obtain a good welding joint.

(Problems to be Solved by the Invention) The present invention has the problem of control instability caused by fluctuation of the detection signal due to the oscillation of the welding torch, which was a problem in the groove tracking control method using the welding arc phenomenon. The present invention provides a swing arc welding method capable of accurately positioning a welding torch and a swing apparatus for arc welding capable of obtaining a stable detection signal.

(Means for Solving the Problems) The gist of the present invention is to correct the swing center position by reciprocating the welding torch in the groove width direction and detecting the fluctuation of the welding current or welding voltage in the vicinity of both ends of the swing. However, in the swing arc welding method in which welding is performed along the welding line, a section defined from both ends of the swing to the center side is provided, and the moving speed of the welding torch in the swing direction in the section is always preset. In the swinging arc welding method, which is performed at a constant speed, and the swinging device for arc welding that controls the swinging of the welding arc using the arc phenomenon, the welding torch is swung in the groove width direction. Torch swing mechanism, swing position detector that detects the position of the welding torch in the swing width direction, swing center position setter that sets the swing center position, swing number setter that sets the number of swings , Set the swing width Width setting device, constant speed interval reference width setting device for setting the reference width of the constant speed interval, judging device for determining the constant speed interval width based on signals from the swing width setting device and the constant speed interval reference width setting device , The swing center position setting device, the swing width setting device, the swing number setting device, and the determination device, the positions of both ends of the swing, the left and right swing speed change points, and the swing of the speed variable section. An arithmetic unit for calculating the speed, a left end setting unit for individually setting each according to the arithmetic result of the arithmetic unit,
Left speed change point setter, right speed change point setter, right end setter and variable speed setter, command circuit that outputs a speed change signal and position selection signal, the left end setter according to a position selection signal from the command circuit, A position selector for transmitting a position signal from any one of the left speed change point setter, the right speed change point setter, and the right end setter to the position setter, and a position signal transmitted from the position selector Or a position setter that stores the position signal transmitted from the swing center position setter and outputs the set position signal to a motor controller,
A constant speed setting device for setting the speed in a constant speed section, a speed switching device for switching the signals from the constant speed setting device and the variable speed setting device in response to a speed change signal from the command circuit, and a speed from the speed switching device. The rotation speed of the swing motor of the torch swing mechanism is controlled in accordance with the signal, and the swing position is detected in accordance with the result of comparison calculation of the detected position signal from the swing position detector and the set position signal from the position setter. An oscillating device comprising a motor controller which outputs a pulse signal for controlling a rotating direction of a dynamic motor or for activating the command circuit.

 The present invention will be described in detail below with reference to the drawings showing examples.

(Operation) FIG. 1 is a waveform diagram showing the relationship between the swing locus and the detection signal waveform according to the present invention, and FIG. 2 is a block diagram of the swing device according to the present invention. From this, a swing center position signal is output to the calculator 7 and the position setter 14. The computing unit 7 receives the swing center position signal from the swing center position setting unit 3, the swing width signal from the swing width setting unit 4, and the constant velocity section width signal from the judging unit 6 to determine the positions of both ends of the swing, the left and right sides. The swing speed change point and the swing speed in the variable speed section are calculated, and the left end setter 8, the right end setter 9, the left speed change point setter 10, the right speed change point setter 11, and the variable speed setter are calculated, respectively. Transmitted to 12. Based on the calculation result, the left end setter 8 swings the left end, the right end setter 9 swings the right end,
The left speed change point setter 10 outputs a left speed change point, and the right speed change point setter 11 outputs a right speed change point position signal. Based on the calculation result, the swing speed signal in the variable speed section from the variable speed setter 12 is the constant speed setter 13
Outputs a swing speed signal in the constant speed section.

A torch holder is attached to the torch swing mechanism 1 via an arm 25.
A welding torch 27 is attached to 26, and is swung by a swing motor 20 in the groove width direction (left and right).

The swing position detector 2 is composed of a pulse generator attached to the swing motor 20 and an up-down counter. The output pulse of the pulse generator generated by the rotation of the swing motor 20 is counted by the up-down counter and the swing torch 27 swings. It is output to the motor controller 16 as a position signal in the moving direction. The motor controller 16 compares the set position signal 31, which is the output signal from the position setter 14, with the welding torch detection position signal 32 from the swing position detector 2, and as a result, the welding torch 27 is located to the left of the set position. To the oscillating motor 20, a rightward signal is output to the oscillating motor 20, and a leftward signal to the right is output, and at the same time, a speed control signal for the oscillating motor 20 is output to the oscillating motor 20 by the speed signal 24 output from the speed switch 18. . The swing motor 20 is rotated by a control signal from the motor controller 16, and the swing mechanism 1 moves the welding torch 27 in the groove width direction. Comparing the output signal from the position setter 14 and the welding torch position signal,
When the results match, the control signal to the welding motor 20 is not output, the pulse signal 23 is output to the command circuit 17,
The command circuit 17 is activated.

The command circuit 17 outputs the position selection signals one by one at a time,
Left speed change point (a) → swing left end (b) → left speed change point (c) → right speed change point (d) → swing right end (e) → right speed change point (f) ) → Output to the position selector 15 in the order of the speed change point (a ₁ ) on the left side. The position selector 15 uses the position selection signal 21 to move the left end of the swing from the left end setter 8, the right end of the swing from the right end setter 9, the left speed change point, the left speed change point from the setter 10, and the right speed change Only one of the right speed change point position signals from the point setter 11 is selected and transmitted to the position setter 14. The position setter 14 stores the new position signal and outputs the new position signal to the motor controller 16. For this reason, the welding torch position and the position signal from the position setter 14 are different, a control signal is output from the motor controller 16 to the swing motor 20, and the welding torch 27 has the speed change point (a) on the left side → the left end of the swing. (B) → speed change point on the left side (c) → speed change point on the right side (d) → right end of swing (e) → speed change point on the right side (f) → speed change point on the left side (a ₁ ) To move sequentially.

Also, from the command circuit 17, a speed switching signal is sent at each speed change point.
22 is output, and the speed signal is switched by the speed switcher 18. The constant speed signal from the constant speed setter 13 is set at the speed change point (a, d), and the variable speed setter is set at the speed change point (c, f). 12
Is transmitted to the motor controller 16.

That is, the speed change point (a) on the left side is stored in the position setter 14 via the position selector 15 by the position selection signal 21 from the command circuit 17, the welding torch 27 moves to the left, and the welding torch position is changed. When it coincides with the speed change point (a) on the left side, the output of the control signal from the motor controller 16 to the swing motor 20 decreases, and at the same time, a pulse signal is output as the command signal 17. The left end (b) of the swing is stored in the position setter 14 via the position selector 15 by the position selection signal 21 from the command circuit 17, and at the same time, the speed change signal 22 is output to the speed changer 18 and the constant speed signal is output. It is transmitted to the motor controller 16. The motor controller 16 sends a leftward control signal at a constant speed to the motor 20.
The welding torch 27 moves to the left at the moving speed given by the constant speed setter 13. Next, when the welding torch position coincides with the left end (b) of the swing, the position setter is operated as described above.
The speed change point (c) on the left side is stored in 14, the output position signal and the welding torch position do not match, and the rightward control signal is output from the motor controller 16 to reverse the swing. Further, when the speed change point (c) on the left side and the welding torch position match, the speed change point (d) on the right side is stored in the position setter 14, and at the same time a speed switching signal is output from the command circuit 17, and the variable speed setter is set. The speed signal set by 12 is transmitted, and the motor controller 16 outputs a rightward signal at the speed set by the variable speed setting device 12 to the swing motor 20. It is sequentially repeated as described above.

Therefore, the speed change point (a) on the left side → the left end of the swing (b) →
Left speed change point (c) and right speed change point (d)
→ The right end of the swing (e) → The swing speed at the speed change point (f) on the right side becomes the constant speed set by the constant speed setting device 13, and swings again after the pulse signal is output from the motor controller 16. The time until the control signal is output to the motor 20 is a very short time of about 50 .mu.sec., And the swing is performed without interruption, and the swing locus shown in FIG. 1 is obtained.

Here, when the constant speed section width signal from the judging device 6 is larger than 1/2 of the swing width set by the swing width setting device 4, the left speed change point (c) → the right speed change point (d). ) And the speed change point (f) on the right side → the speed change point (a ₁ ) on the left side cannot exist, and the number of swings is fixed. Therefore, in the apparatus of the present invention, in order to solve this problem, the determiner 6 sets the reference width of the constant speed section set by the constant speed section reference width setting unit 5 and the swing width set by the swing setting width 4. 1 /
The width signal of whichever is narrower is transmitted to the calculator 7 as a constant speed width signal. That is, the left speed change point (a) → the left end of the swing (b) → the left speed change point (c) and the right speed change point (d) → the right end of the swing (e) → the right speed change point By setting the width of the constant velocity section in (f) to 1/4 or less of the swing width, the speed change point (a) on the left side → the left end (b) of the swing → the left side of the swing even in the area where the swing width is narrow. The number of swings can be changed while securing a constant speed section of the speed change point (c) and the right speed change point (d) → the right end (e) of the swing → the right speed change point (f).

When the swing is not performed, the swing center position signal output from the swing center position setter 3 is output to the position setter 14, and the command circuit 17 is not activated. Therefore, the welding torch 27 is held at the swing center position.

Center of swing of swing center position setter 3, swing width setter 4
The swing width and the number of swings of the swing number setting device 19 are changed by a scanning signal from a groove scanning control circuit (not shown). When any of the three set values is changed, the calculator 7 calculates the positions of both ends of the swing, the swing speed change points on the left and right, and the swing speed of the speed variable section, and the left end setter 8 , The right end setter 9, the left speed change point setter 10, the right speed change point setter 11, and the variable speed setter 12 are updated to correct the swing position.

The swing mechanism 1 is attached to the traveling carriage 29 in the groove width direction orthogonal to the traveling direction, and the welding torch 27 is moved in the swing direction.
Can be moved 100 mm. Further, the traveling carriage 29 is attached to a rail 30 installed substantially parallel to the groove, and the welding torch 1 is positioned at the center of the groove to start welding. Simultaneously with the start of welding, the traveling carriage 29 starts to swing on the rail width direction and move on the rail 30.

At this time, the swing locus is as shown in FIG. 1, with respect to changes in the swing width and the number of swings, the speed change point on the left side (c) → the speed change point on the right side (d) and the speed on the right side. Change point (f) → Left side speed change point set at both ends of swing only by changing the moving speed of welding torch 27 in the swing width direction in the speed change area of left side speed change point (a ₁ ) (A) → left end of swing (b) → left speed change point (c) and right speed change point (d) → right end of swing (e) → right speed change point (f) constant speed section Since the moving speed of the welding torch 27 in the swing width direction is constant regardless of changes in the swing width and the number of swings, the amount of change in the distance between the chap and the base metal due to the groove wall surface is constant. That is, the welding current waveform has a speed change point (a) on the left side of both ends of the swing → a left end (b) of the swing → a speed change point (c) on the left side and a speed change point (d) on the right side → a right end of the swing ( e) → In the constant speed section of the speed change point (f) on the right side, a constant signal waveform can be obtained without being affected by changes in the swing width and the number of swings.

Therefore, since the welding current and the welding voltage change only due to the change in the positional relationship between the swing end and the groove wall surface, the groove control with high accuracy by the copying control circuit (not shown) is performed regardless of the change in swing. The position of the wall surface can be detected, the groove tracking control with high tracking accuracy is enabled, and good welding results can be obtained. Even if the welding voltage is used as the detection signal, the same result as the welding current can be obtained.

(Effect of the Invention) According to the present invention as described above, since the swing locus at both ends of swing is always constant, the changes in the welding current and the welding voltage near both ends of swing can be changed with time. Since the moving position is always a constant condition, it can be applied to any sensing technology that uses the arc phenomenon of the groove wall surface due to the oscillation of the arc, and it has made possible highly accurate detection.

In addition, in the welding method in which the arc is oscillated, the groove wall surface is detected by the change of the welding current or welding voltage, the groove position is recognized, and the oscillation center and oscillation width are held at the optimum position. By solving the fundamental problem of groove-probe control that prevents detection error due to change in arc swing speed in the swing width direction due to changing conditions and putting high-precision groove-probe control into practical use, sound Industrially excellent effects such as stable welding can be obtained.

[Brief description of drawings]

FIG. 1 is a waveform diagram showing a swing locus and a detection signal waveform according to the present invention, FIG. 2 is a block diagram of the swing device according to the present invention, and FIGS. 3 to 7 are a relation between a swing arc and a groove wall surface and welding. FIG. 8 is an explanatory diagram showing the relationship between the electric current and the welding voltage, and FIGS. 8 to 11 are explanatory diagrams showing the relationship between the swing locus and the detection signal. 1 ... torch swing mechanism, 2 ... swing position detector, 3 ...
Oscillation center position setting device, 4 ... Oscillation width setting device, 5 ... Constant speed section reference setting device, 6 ... Judgment device, 7 ... Computing device, 8 ...
Left end setter, 9 ... Right end setter, 10 ... Left speed change point setter, 11 ... Right speed change point setter, 12 ... Variable speed setter, 13 ... Constant speed setter, 14 ... Position setter, 15 …… Position selector, 16 …… Motor controller, 17 …… Command circuit, 18 …… Speed changer, 19 …… Rotation frequency setter, 20 ……
Swing motor, 21 …… Position selection signal, 22 …… Speed change signal, 23 …… Pulse signal, 24 …… Speed signal, 25 …… Arm, 26 …… Torch holder, 27 …… Welding torch, 28 …… Open Front wall, 29 …… Truck, 30 …… Rail, 31 …… Set position signal, 32 …… Detected position signal.

Claims (2)

[Claims] 1. A swing for performing welding along a welding line while reciprocating a welding torch in the groove width direction to detect a variation in welding current or welding voltage near both ends of the swing and correcting the swing center position. In the arc welding method, a swing arm welding is characterized in that a section defined from both ends of swing to a center side is provided, and a moving speed in the swing direction in the section is always a preset constant speed. Law. 2. An oscillating device for arc welding for controlling the oscillating of a welding arc by utilizing an arc phenomenon. A torch oscillating mechanism (1) for oscillating a welding torch (27) in a groove width direction, A swing position detector (2) that detects the position of the welding torch in the width direction, a swing center position setter (3) that sets the swing center position, and a swing number setter that sets the number of swings ( 19), a swing width setting device (4) for setting a swing width, a constant speed section reference width setting device (5) for setting a reference width of a constant speed section, the swing width setting device and the setting section reference A judging device (6) for judging the constant speed section width based on a signal from the setting device (5), the swing center position setting device (3), the swing width setting device (4),
A calculator (7) for calculating the positions of both ends of the rocking, the rocking speed change points on the left and right, and the rocking speed in the speed variable section based on signals from the rocking frequency setting device (19) and the judging device (6), A left end setter (8), a left speed change point setter (10), a right speed change point setter (11), a right end setter (9) and A variable speed setting device (12), a command circuit (17) that outputs a speed change signal (22) and a position selection signal (21), and the left end setting device (8) from the command circuit (17) by a position selection signal (21). ), A position signal from any one of the left speed change point setter (10), the right speed change point setter (11) and the right end setter (9) is transmitted to the position setter (14). A position selector (15), a position signal transmitted from the position selector (15), or
A position setter (14) that stores the position signal transmitted from the swing center position setter (3) and outputs the set position signal (31) to the motor controller (16), and sets the speed in a constant speed section A constant speed setting device (13), a speed switching device (18) for switching the signals from the constant speed setting device (13) and the variable speed setting device (12) by a speed change signal (22) from the command circuit (17). ), The rotation speed of the swing motor (20) of the torch swing mechanism (1) is controlled according to the speed signal (24) from the speed switch (18), and the swing position detector (2). The rotation direction of the swing motor (20) is controlled according to the result of the comparison calculation of the detected position signal (32) from the position setter (14) and the set position signal (31) from the position setter (14), or the command circuit (17). Motor controller (1 that outputs a pulse signal (23)
6), An oscillating device comprising: