JPS63248575A - Oscillating arc welding method and oscillating device - Google Patents

Abstract

PURPOSE:To obtain a sound welded joint by providing a fixed section from both edges of oscillation to its central side and making the travel speed in the oscillating direction in said section to the preset constant speed to profile a groove line stably with the high accuracy. CONSTITUTION:A speed changing point (a) at the left side is stored in a position setter 14 by a position selection signal 21 from a command circuit 17 and when a welding torch 27 is moved to the left and conforms to the speed changing point (a) at the left side, a pulse signal is outputted to the command circuit 17. A left end (b) of the oscillation is stored in the position setter 14 by the position selection signal 21 from the circuit 17 and a speed changing signal 22 is outputted to a speed changeover apparatus 18 and a constant speed signal is transmitted to a motor controller 16. The controller 16 outputs a left-handed control signal to a motor 20 and when the torch 27 is moved to the left at the speed by a constant speed setter 13 and conforms to the left and (b), a speed changing point (c) at the left side is stored and a right-handed signal is outputted from the controller 16 and the oscillation is reversed. When the speed changing point (c) at the left side conforms to the torch position, the right-handed signal is outputted to the motor 20 by a speed changeover signal from the circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to an automatic arc welding method that performs groove tracing control by controlling the oscillation of the welding arc using arc phenomena, particularly in the oscillating arc welding process. This invention relates to a welding method and a rocking device for automatic arc welding.

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

In general, for weaving welding in Welding Encyclopedia Vol. 6 [Fused Welding Equipment J (P) 48-150], the swing mechanism is a method in which the crankshaft is rotated and the welding torch is swung around a fulcrum by a link mechanism. is widely known as a typical mechanism.

In addition, as a method using the welding arc phenomenon, JP-A No. 5
In Japanese Patent No. 8-176076, the welding torch is reciprocated in parallel to the width direction of the welding progress direction so that the difference between the detection signal at the center of the oscillation and the detection signal at the end of the oscillation matches a reference value. A swing width control method has been proposed. Further, in Japanese Patent Publication No. 57-3462, the welding torch is moved up and down to change the distance from the base metal surface so as to keep the arc voltage constant, and the welding torch is reciprocated in parallel to the width direction of the welding progress direction. A constant velocity reversal oscillation has been proposed in which the direction of the reciprocating movement in the width direction is changed every time the vertical displacement height of the welding torch becomes equal to a predetermined set value.

However, the changes in the welding current or welding voltage that we are trying to detect here were generally thought to fluctuate due to changes in the distance between the tip and the base metal, but in reality, as shown in Figure 3, In the process in which the tip of the welding wire approaches the right or left groove wall surface 28, that is, in the process in which the distance between the tip and the base metal becomes shorter, the arc length becomes shorter because the change in the wire protrusion length lags behind the change in the arc length. The welding current is high and the welding voltage is low. In addition, in the process of reversing the oscillation at both ends of the oscillation and moving away from the right or left groove wall surface 28 as shown in Fig. 4, that is, in the process of increasing the distance between the chip and the base metal, the arc length becomes longer. Since the welding current is small and the welding voltage is high, the welding current changes near both ends of the swing as shown in FIG. 5, and the welding voltage changes as shown in FIG. 6. Therefore, the welding current and welding voltage when the arc is oscillated within the groove are as shown in FIG.

Taking advantage of this phenomenon, the inventors published patent application No. 1i0-249
In No. 958, we proposed a groove tracing control method by detecting the area and R of the figure drawn by the welding current and swing position shown in Figure 7 (b). However, the changes in welding current and welding voltage near both ends of the oscillation are due not only to changes in the tip-to-base metal distance but also to the rate of change in the tip-to-base metal distance, and this oscillation The speed of change in the distance between the chip and the base material near both ends of the motion is affected by the speed of movement in the swing direction. In other words, the amount of change in the welding current and welding voltage can be changed by increasing the oscillation width under a constant oscillation period, or by increasing the number of oscillations under a constant oscillation width and changing the movement speed in the oscillation width direction. When speeding up, the amount increases as shown in FIG. For this reason,
Especially in groove width tracing control, which detects the groove width based on the amount of change in the welding current or welding voltage at both ends of the swing and follows the swing width to the groove width, the swing width is optimal as shown in Figure 9. The groove becomes narrower than the specified value, causing defects due to poor fusion at some of the groove corners.

Conversely, if the movement speed in the oscillation width direction is slowed down, the amount of change in welding current and welding voltage will decrease as shown in Figure 10, so the oscillation width will become wider than the optimum value as shown in Figure 11, and the arc This excavates the groove wall surface, causing an undercut on the groove wall surface, which causes defects such as poor fusion and slag entrainment in the next pass.

Therefore, in automatic welding that uses welding line tracing control, which detects welding current or welding voltage changes near both ends of the oscillation and corrects the oscillation center position and oscillation width point by point based on the results, the detection result is the oscillation width. It is necessary to keep the moving speed in the swinging direction constant so as not to be affected by fluctuations in the moving speed in the swinging direction due to changes in the number of swings or changes in the number of swings.

However, none of the above methods takes into account the effect of oscillation on fluctuations in welding current and welding voltage. This method has the disadvantage that the moving speed in the swing width direction must be changed, and the swing conditions cannot be freely selected. Therefore, in automatic welding that uses welding line tracing control that detects changes in welding current or welding voltage near both ends of the oscillation, it is difficult to consistently follow the groove line with a high degree of machining using the conventional oscillation method. There is a problem that a sound weld joint cannot be obtained.

(Problems to be Solved by the Invention) The present invention solves the instability of control due to variations in detection signals caused by swinging of the welding torch, which was a problem with the groove tracing control method using the welding arc phenomenon. The object of the present invention is to provide an oscillating arc welding method that solves the above problems and allows accurate positioning of a welding torch, and an oscillating device for arc welding that allows stable detection signals to be obtained.

(Means for Solving Problems) The gist of the present invention is to reciprocate the welding torch in the groove width direction, detect fluctuations in the welding current or welding voltage near both ends of the swing, and correct the swing center position. In the oscillating arc welding method, in which welding is performed along the welding line, a predetermined section is provided from both ends of the oscillation toward the center, and the moving speed of the welding torch in the oscillation direction in this section is always set in advance. In the oscillating arc welding method, which is characterized by performing the welding at a constant speed, and in the arc welding oscillation device that controls the oscillation of the welding arc using arc phenomena, the welding torch oscillates in the groove width direction. A torch swinging mechanism that detects the position of the welding torch in the swinging width direction, a swinging position detector that detects the position of the welding torch in the swinging width direction, a swinging center position setting device that sets the center position of swinging, and a swinging number setting device that sets the number of swinging times. , an oscillation width setting device that sets the oscillation width, a constant speed section reference width setting device that sets the reference width of the constant speed section, and signals from the oscillation width setting device and the constant speed section reference width setting device. A determiner for determining the constant speed section width, the swing center position setter, the swing width setter, the swing number setter, and the signals from the determiner to determine the positions of both swing ends and the left and right swing speeds. A calculator that calculates the change point and the swing speed of the speed variable section, a left end setter that sets each separately according to the calculation results of the calculator, a left speed change point setter, a right speed change point setter, and a right end setter. and a variable speed setter, a command circuit that outputs a speed change signal and a position selection signal, and a position selection signal from the command circuit that outputs the left end setter, the left speed change point setter, the right speed change point setter, and the A position selector that transmits a signal from any one of the right end setters to the position setter, a position setter that stores the position signal from the position selector or the swing center position setter, and a constant speed section. constant speed setting device to set the speed of
A speed switcher that switches signals from the constant speed setter and the variable speed setter in response to a speed change signal from the command circuit, and a rotational speed of the swing motor of the torch swing mechanism based on the speed signal from the speed switcher. and a motor controller that outputs a control signal for controlling the rotational direction of the swing motor and a pulse signal for activating the command circuit based on the result of comparing and calculating the position signals from the swing position detector and the position setting device. The rocking device is characterized by:

The present invention will be described in detail below based on figures showing examples.

(Function) 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 there, a swing center position signal is output to the calculator 7 and the position setting device 14. The calculator 7 uses the swing center position signal from the swing center position setter 3, the swing width signal from the swing width setter 4, and the constant speed section width signal from the determiner 6 to determine the positions of both ends of the swing, left and right. The oscillation speed change point and the oscillation speed of the speed variable section are calculated, and the left end setter 8, right end setter 9, left speed change point setter 10, right speed change point setter 11, and variable speed setter are calculated. 12. Based on the calculation results, the left end setter 8 sets the left end of the swing, the right end setter 9 sets the right end of the swing, the left speed change point setter 10 sets the left speed change point, and the right speed change point setter 11 sets the left end of the swing. The position signal of the speed change point on the right side is output. Based on the calculation result, the variable speed setter 12 outputs a swing speed signal in the variable speed section, and the constant speed setter 13 outputs a swing speed signal in the constant speed section.

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

The swing position detector 2 is composed of a pulse generator attached to the swing motor 20 and an up/down counter, and the up/down counter counts output pulses of the pulse generator as the swing motor 20 rotates, and the welding torch 2
Motor controller as a position signal in the swing direction of 7]6
Output to. The motor controller 16 is the position setting device 1
The output signal from the welding torch 27 is compared with the welding torch position signal, and as a result, when the welding torch 27 is to the left of the set position, a rightward signal is generated, and when it is to the right, a leftward signal is generated. A speed control signal for the swing motor 20 is output to the swing motor 20 based on the speed signal output from the swing motor 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. The output signal from the position setting device 14 and the welding torch position signal are compared, and when the results match, a control signal to the welding motor 20 is not output, but a pulse signal is output to the command circuit 17, and the command Activate circuit 17.

The command circuit 17 sends the position selection signal one by one in one operation, from the left speed change point (a) → the left end of the swing (b) → the left speed change point (C) → the right speed change point ( d) -> right end of swing (e) -> right speed change point (f) -> left speed change point (al) in the order of output to the position selector 15. The position selector 15 selects 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 from the left speed change point setter 10, and the right speed change according to the position selection signal 21. Only one of the position signals of the speed change point on the right side from the point setter 11 is selected and transmitted to the position setter 14. Position setting device 14
stores this new position signal and sends the motor controller 16
Outputs a new position signal to. Therefore, the welding torch position and the position signal from the position setter 14 are different, and the motor controller 16 outputs a control signal to the swing motor 20, and the welding torch 27 moves from the left speed change point (a) to the left end of 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)
→Move sequentially in the order of speed change points (al) on the left.

Further, the command circuit 17 outputs a speed switching signal 22 at each speed change point, the speed switch 18 switches the speed signal, and at the speed change points (a, d), the constant speed setting device 13
At speed change points (c, f), a variable speed signal from the variable speed setter 12 is transmitted to the motor controller 16.

That is, in response to the position selection signal 21 from the command circuit 17, the left speed change point (
a) is stored, and when the welding torch 27 moves to the left and the welding torch position matches 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 stops. At the same time, a pulse signal is output to the command circuit 17. Position selection signal 2 from the command circuit 17
1, the left end (b) of the swing is stored in the position setter 14 via the position selector 15, and at the same time a speed change signal 22 is output to the speed switch 18 and a constant speed signal is transmitted to the motor controller 16.

The motor controller 16 outputs a constant speed leftward control signal to the motor 20, and the welding torch 27 outputs a constant speed leftward control signal to the motor 20.
Move to the left with the movement speed given by 3. Next, when the welding torch position matches the left end of the swing (b), the left speed change point (C) is stored in the position setting device 14 in the same way as above, and the output position signal and welding torch position do not match. First, a rightward control signal is output from the motor controller 16, and the oscillation is reversed. Furthermore, when the speed change point (C) on the left side matches the welding torch position, the speed change point (d) on the right side is stored in the position setting device 14, and at the same time, a speed switching signal is output from the command circuit 17, and the variable speed setting device 14 outputs a speed change signal. The speed signal set at variable speed setter 12 is transmitted, and the motor controller 16 outputs a rightward signal at the speed set at variable speed setter 12 to swing motor 20. The above steps are repeated in sequence.

Therefore, left speed change point (a) → left end of swing (b) → left speed change point (C) and right speed change point (d) →
The oscillation speed from the right end of oscillation (e) to the speed change point (f) on the right side becomes the constant speed set by the constant speed setting device 13, and after a pulse signal is output from the motor controller 16, the oscillation motor starts again. The time it takes for the control signal to be outputted to the controller 20 is approximately 50 .mu.SeC, which is an extremely short period of time, and the oscillation is performed without interruption, resulting in the oscillation locus shown in FIG.

Here, the constant speed section width signal from the determiner 6 is transmitted to the oscillation width setting device 4.
When the swing width is larger than 172, the left speed change point (c) → right speed change point (d) and the right speed change point (f) → left speed change point (a,) There is no longer a variable speed section, and the number of swings is fixed. Therefore, in order to solve this problem in the apparatus of the present invention, the determiner 6 uses the reference width of the constant speed section set by the constant speed section reference width setting device 5 and the swing width set by the swing width setting device 4. 174, and the narrower width signal is transmitted to the arithmetic unit 7 as a constant speed width signal. That is, the left speed change point (a) → left end of swing (b) → left speed change point (C) and right speed change point (d) → right end of swing (
e) → By setting the width of the constant speed section at the speed change point (f) on the right side to 174 or less of the swing width, even in an area where the swing width is narrow, the speed change point on the left side (a) → the left end of the swing (b) → The speed change point on the left (C) and the speed change point on the right (d) → The right end of the swing (e) → The number of swings while ensuring the constant speed section at the speed change point on the right (f) It is changeable.

Further, when no rocking is performed, the rocking center position signal output from the rocking center position setting device 3 is output to the position setting device 14, and the command circuit 17 is not activated. Therefore welding torch 2
7 is held at the swing center position.

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

The swinging mechanism 1 is attached to the traveling carriage 29 in the groove width direction perpendicular to the running direction, and can move the welding torch 27 by 100 mm in the swinging direction. Further, the traveling carriage 29 is attached to a rail 30 installed approximately 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 carriage 29 starts swinging in the groove width direction and moving on the rail 30.

At this time, the oscillation locus is shown in Fig. 1, in particular the oscillation width,
For changes in the number of oscillations, change the speed at the left speed change point (C) →
Speed change point on the right side (d) and speed change point on the right side (f)
→ Only the moving speed of the welding torch 27 in the swing width direction in the speed variable section of the left speed change point (a,) changes. Left end of movement (b) → Left speed change point (C) and right speed change point (d) → Right end of swing (e) → Right speed change point (f
) The moving speed of the welding torch 27 in the swing width direction in the constant speed section of The amount will be constant. In other words, the welding current waveform changes from the speed change point on the left side of both ends of the swing (a) → the left end of the swing (b) → the speed change point on the left side (
C) and speed change point on the right side (d) → right end of swing (e)
→In the constant speed section at 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 or the number of swings.

Therefore, since the welding current and welding voltage change only due to changes in the positional relationship between the swinging end and the groove wall surface, a high-precision groove control circuit (not shown) can be used regardless of swinging changes. By making it possible to detect the position of the wall surface, we were able to perform groove tracing control with high tracking accuracy, and were able to obtain good welding results. Note that the same results as the welding current can be obtained even if the welding voltage is used as the detection signal.

(Effects of the Invention) As described above, according to the present invention, since the swing locus at both ends of the swing is always constant, changes in welding current and welding voltage near both ends of the swing change with respect to time. Since the condition is always constant for the moving position, it can be applied to all kinds of sensing technology that utilizes the arc phenomenon on the groove wall surface due to the swinging of the arc, and has made it possible to achieve highly accurate detection.

In addition, in a welding method in which the arc is oscillated and the groove wall surface is detected by changes in the welding current or welding voltage, the groove position is recognized and the oscillation center and oscillation width are maintained at the optimal position. By solving the fundamental problem of groove tracing control, which is preventing detection errors due to changes in the moving speed of the arc in the oscillation width direction due to changes in conditions, and by putting high-precision groove tracing control into practical use, we have achieved sound welding. It brings about excellent industrial effects, such as being able to stably obtain .

[Brief Description of the Drawings] Fig. 1 is a waveform diagram showing the swing locus and detection signal waveform according to the present invention, Fig. 2 is a block diagram of the swing device of the present invention, and Figs. FIGS. 8 to 11 are explanatory diagrams showing the relationship between the groove wall surface, welding current, and 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... Rocking position detector, 3
... Oscillation center position setter, 4... Oscillation width setting device, 5
・・・Constant speed section reference width setter, 6... Judgment device, 7...
・Arithmetic unit, 8...Left end setting device, 9...Right end setting device,
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,】6・・Motor controller, 17・・Command circuit, 18・・Speed switch, ] 9・・・Swing number setting device, 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 ... Groove wall surface,
29...Traveling trolley, 30...Rail.

Claims (2)

[Claims] (1) Oscillating arc welding in which the welding torch is reciprocated in the groove width direction, detecting fluctuations in welding current or welding voltage near both ends of the oscillation, and welding along the welding line while correcting the oscillation center position. An oscillating arc welding method characterized in that a section is provided from both ends of the oscillation toward the center, and the speed of movement in the oscillation direction in the section is always a preset constant speed. (2) In an arc welding oscillation device that controls the oscillation of the welding arc using arc phenomena, a torch oscillation mechanism that oscillates the welding torch in the groove width direction, and a position of the welding torch in the oscillation width direction. oscillation position detector to detect the oscillation center position, oscillation center position setter to set the oscillation center position, oscillation number setting device to set the number of oscillations, oscillation width setting device to set the oscillation width, A constant speed section reference width setter that sets a reference width of the speed section, a determiner that determines the constant speed section width based on signals from the swing width setter and the constant speed section reference width setter, and the swing center position. A computing unit that calculates the positions of both ends of the swing, left and right swing speed change points, and the swing speed of the variable speed section based on the signals from the setting device, the swing width setting device, the swing number setting device, and the determining device. , a left end setting device, a left speed change point setting device, a right speed change point setting device, each of which is set separately according to the calculation result of the calculation unit;
A right end setter and a variable speed setter, a command circuit that outputs a speed change signal and a position selection signal, and a position selection signal from the command circuit to set the left end setter, the left speed change point setter, and the right speed change point. a position selector that transmits a signal from any one of the position selector and the right end setter to the position setter, a position setter that stores the position signal from the position selector or the swing center position setter, and a constant speed. a constant speed setter that sets the speed of the section; a speed switch that switches signals from the constant speed setter and the variable speed setter in response to a speed change signal from the command circuit; A control signal for controlling the rotational direction of the swing motor and the command circuit are activated based on the result of comparing and calculating the rotational speed of the swing motor of the torch swing mechanism and the position signals from the swing position detector and the position detector. A rocking device comprising: a motor controller that outputs a pulse signal to generate a pulse signal.