JPS6255476B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for automatically tracing a groove while making a welding torch perform rectangular oscillation in automatic arc welding with a groove.

[Conventional technology]

In automatic arc welding with a groove, by detecting the approach of the electrode to the groove wall,
The welding torch is automatically caused to follow the groove. A conventional method for detecting the approach of the electrode to the groove wall is to detect the groove edge (the upper end of the groove wall) by pattern recognition using optical means. However, this method has the drawback that since the detection position and the electrode tip are far apart, correction is required depending on the depth of the groove and the angle of the groove wall.

Another detection method is to detect changes in welding current, welding voltage, or arc light intensity. However, since the values of these detection elements fluctuate due to changes in arc phenomena such as shielding gas, it has not been possible to accurately detect the approach state of the electrode to the groove wall using this method. Furthermore, since no arc was generated before welding, it was not possible to check the tracing state. Therefore, the welding setting values had to be adjusted after arcing occurred, and automatic start could not be performed.

Therefore, as a method to solve the drawbacks of these detection methods, Japanese Patent Publication No. 50-23375 and Utility Model Publication No. 51-
There was a detection method described in Publication No. 7312. This is done by placing contacts made of levers, springs, etc. on both the left and right sides of the electrode, and by detecting when these contacts touch the groove wall, the groove wall is detected and the welding torch follows the groove. It was designed to make it easier. According to this method, compared to the method using pattern recognition or the method of detecting changes in welding current, welding voltage, or arc light intensity, detection of groove walls does not require correction, and is independent of changes in arc phenomena. It has advantages such as being able to trace the groove accurately and being able to detect an arc even if it is not occurring.

[Problem that the invention seeks to solve]

In this way, by using a detection mechanism in which contacts are arranged on both the left and right sides of the electrode, it is possible to perform copy welding by accurately detecting the groove wall, but the copy welding method disclosed in Japanese Patent Publication No. 50-23375 mentioned above Since the contact is used only to detect the touch of the groove wall when the electrode is moved perpendicular to the groove wall, only copy welding using triangular oscillation is possible.

Furthermore, in the copying method disclosed in Japanese Utility Model Publication No. 51-7312, the contact is only used for the purpose of issuing an alarm when the contact touches the groove wall.
Not used for oscillation.

This invention aims to provide an automatic arc tracing method that enables tracing welding by rectangular oscillation using the above contactor.

[Means for solving problems]

In this invention, the welding torch is supported by a traveling drive means that travels in the longitudinal direction of the groove and a traveling drive means that travels laterally in the width direction of the groove. An automatic arc welding tracing method in which two contacts that move together are arranged, and the touches of these left and right contacts on the left and right groove walls are respectively detected, and the welding torch follows the groove. a first drive control for stopping the drive means and driving the traverse drive means leftward; and a first drive control for driving the travel drive means forward and driving the traverse drive means rightward when a touch on the left wall is detected. a second drive control for driving leftward when a touch on the left wall is not detected; a third drive control for stopping the travel drive means and driving the traverse drive means rightward; and a third drive control for driving the travel drive means rightward. and a fourth drive control in which the means is driven forward, and the traverse drive means is driven leftward when a right wall touch is detected, and driven rightward when a right wall touch is not detected, and the fourth drive control is sequentially repeated. At the same time, the first
When a touch on the left wall is detected while the drive control is being executed, the switch is switched to the second drive control, and when the vehicle has traveled a predetermined distance from the start of the second drive control while the second drive control is being executed, the switch is switched to the second drive control. Switch to drive control of 3.
When a touch on the right wall is detected during execution of this third drive control, the switch is made to the fourth drive control, and while executing this fourth drive control, the vehicle travels a predetermined distance from the start of this fourth drive control. The present invention is characterized in that the drive control is switched to the first drive control when the drive control is performed.

[Effect]

According to this invention, the welding torch travels toward the left wall under the first drive control, travels along the left wall under the second drive control, and travels to the right toward the right wall under the third drive control. Then, it travels along the right wall under the fourth drive control, and by sequentially repeating this operation, copy welding by rectangular oscillation is realized.

In the second and fourth drive controls, when the contact touches the groove opening, it moves away, and when it leaves, it touches it, so the transverse drive is performed, so even if the groove line is curved, it is accurately aligned. can be made to imitate.

〔Example〕

Examples of this invention will be described below.

FIG. 1 shows the mechanical part of an automatic welding device to which the present invention is applied. Figure 2 is its side view.
FIG. 3 is a front view thereof. This welding device includes an X-axis for moving the welding torch 1 in the direction along the groove 3 of the base material 2, a Y-axis for moving the welding torch 1 laterally in the left-right direction, and a Z-axis for moving the welding torch 1 in the vertical direction. For each of these axes, a servo control system is constructed that provides precise feedback using a drive motor with rotational feedback and a position detector.

A welding torch 1 and a welding torch 1 are mounted on both sides of the trolley 4.
A traveling wheel 5 is provided as a traveling drive means for moving the vehicle in the X-axis direction. This running wheel 5 is driven by a motor 6. A screw 7 is disposed on the truck 4. This screw 7 is for moving the welding torch 1 in the Z-axis direction, and is driven by a motor 8. A screw 9 is disposed on the screw 7 as a traverse drive means. This screw 9 is for moving the welding torch 1 in the Y-axis direction, and is controlled by a motor 11. Welding torch 1 is attached to screw 9 via connection 1a.

A torch nozzle 12 is arranged in the welding torch 1 so as to face vertically downward. An electrode 13 protrudes from the tip of the torch nozzle 12.

A wire reel 14 is disposed on the trolley 4, and a feed motor 16 transports the filler wire 15 from the front in the welding direction through a roller 17, a conduit 18, and a wire tip 19 to a molten pool 20 directly below the electrode 13. is supplied to. The wire tip 19 is supported by a wire tip holder 21 attached to the welding torch 1.

The welding torch 1 has two sensor lobes (contactors) 25 and 26, the tip of which is connected to the filler wire 1.
It is arranged so that it is located on both sides of 5. The sensor probes 25 and 26 are made of thin metal wires, and a voltage is applied between them and the base material 2. Therefore, in the process of automatic welding, if it is detected that the sensor probes 25, 26 touch the groove walls 3a, 3b due to the voltage or current between the base metal 2 and the sensor probes 25, 26, the electrode 13 and The state of proximity to the groove walls 3a and 3b can be detected.

Note that the sensor probes 25 and 26 are connected to the groove wall 3.
The vicinity of the attachment part to the welding torch 1 is formed in a coil shape so that the welding torch 1 is not bent due to the contact with the welding torch 1. In addition, both sensor probes 25, 2
A spacing adjuster 27 is disposed between the spacings 6 and 6 to adjust the spacing between them. This interval adjuster 27
As shown in FIG. 4, it is composed of a wedge-shaped piece, and is supported by the wire tip holder 21 so as to be movable in the direction of arrow A, and is fixed with a screw 28, so that both sensor probes 25 and 26 can be connected as appropriate. is configured to be set to an interval of Power sources for the sensor probes 25 and 26, a welding power source, shielding gas, etc. are supplied from a collecting conduit 29.

When performing automatic welding using the oscillation method with the above welding device, for example, as shown in Fig. 3, while moving the cart 4 forward in the X-axis direction, the welding torch 1 is moved in the Y-axis direction (to the left). When the sensor probe 25 touches the left groove wall 3a, the direction is reversed and the sensor probe 25 is moved to the right.
When it touches the right groove wall 3b, the direction can be reversed again and these operations can be repeated.

FIG. 5 is a circuit diagram showing an example of a control device for implementing the copying method according to the present invention using a microcomputer. In FIG. 5, the portion surrounded by dotted lines 70 is a touch detection circuit for the left and right groove walls.
The AC voltage supplied from the power supply 30 is rectified by the diode bridge 32 via the power transformer 31, the positive voltage is led to the left sensor probe 25 via the resistor R1, and the negative voltage is led to the right sensor probe via the resistor R2. led to the sensor probe 26, zero voltage is applied to the resistor R
4, is led to the base material 2 via R3. Also,
This rectified voltage is applied to a circuit including the diode D1, the light emitting diode Df1, the transistor Q1, and the resistor R5, and a circuit including the resistor R5, the transistor Q2, the light emitting diode Df2, and the diode D2. Phototransistors Qf1 and Qf2 are combined with the light emitting diodes Df1 and Df2, respectively. A voltage at the connection point between resistors R3 and R4 is applied to the bases of transistors Q1 and Q2 via resistor R6. Therefore, when the left sensor probe 25 touches the left groove wall 3a, the transformer 31→diode bridge 32→resistance R1→
Left sensor probe → Base material 2 → Resistor R3 → Resistor R4
→A current flows through the path of the transformer 31, the base potentials of the transistors Q1 and Q2 become positive, the transistor Q1 is turned on, the light emitting diode Df1 emits light, and a voltage is obtained at the output 33 of the phototransistor Qf1.

Also, when the right sensor probe 26 touches the right groove wall 3b, the transformer 31 → resistor R4 → resistor R
3 → Base material 2 → Right sensor probe 26 → Resistor R2 →
Current flows through the path of the diode bridge 32, and the base potentials of the transistors Q1 and Q2 become negative, turning on the transistor Q2 and turning on the light emitting diode.
Df2 emits light and a voltage is obtained at the output 34 of phototransistor Qf2. Therefore, by detecting the voltages at the output terminals 33 and 34, the touch between the sensor probes 25 and 26 and the base material 3 can be detected.

The left and right touch detection signals obtained from the output terminals 33 and 34 and the travel amount detection signal obtained from the travel amount detector 62 (for example, a rotary encoder) are input to the microcomputer 71.

The microcomputer 71 determines the control content to be executed based on these detection signals, outputs a drive signal to execute the control, and controls the traverse motor 11 and the travel motor 6 via drive circuits 72 and 73. Drive each.

Next, an example in which the copying method of the present invention is performed using the welding apparatus described above will be described. Here, as shown in FIG. 6, the robot is moved to the left in the Y-axis direction (a), and when it is detected that the left sensor probe 25 touches the left groove wall 3a, the left movement is stopped. Next, it is moved forward in the X-axis direction, corrected in the Y-axis direction, and moved along the left groove wall 3a.
(b) After traveling a specified distance (or a specified time), stop the vehicle and move to the right in the Y-axis direction.
(c). Then, the right sensor probe 2 is attached to the right groove wall 3b.
When it is detected that 6 has been touched, it stops moving to the right, moves forward in the X-axis direction, makes corrections in the Y-axis direction, and moves along the right groove wall 3b (d). After driving a certain distance (or a certain time),
Stop the vehicle and move it to the left in the Y-axis direction.
(a), the above operation is repeated.

FIG. 7 is a flowchart for realizing the above operation. This flow will be explained step by step.

(1) Set the electrode 13 into the groove 3 before starting welding. At this time, the movement of each axis in the tracing state can be confirmed using the sensor probes 25 and 26 without arcing.

(2) When the welding start operation is performed, it is driven to the left in the Y-axis direction.

(3) When the left sensor probe 25 touches the left groove wall 3a, the leftward drive is stopped and the drive is started in the X-axis direction.

(4) When driving, the Y-axis direction is corrected and controlled so that the left sensor probe 25 remains in a state where it only touches the left groove wall 3a. That is, when the left sensor probe 25 leaves the left groove wall 3a, it moves leftward (to approach the left groove wall 3a), and when it touches the left groove wall 3a, it moves to the right (left groove wall 3a). Front wall 3a
drive rightward in the direction away from the Thereby, even if the left groove wall 3a is curved in the middle, it can be made to follow the curve.

(5) After running the vehicle for a predetermined time (or distance), stop the drive.

(6) Next, drive rightward in the Y-axis direction.

(7) When the right sensor probe 26 touches the right groove wall 3b, the rightward drive is stopped and the drive is driven in the X-axis direction.

(8) When running, the Y-axis direction is corrected and controlled so that the right sensor probe 26 maintains a state in which it touches or does not touch the right groove wall 3b. That is, when the right sensor probe 26 moves away from the right groove wall 3b, it is driven rightward (towards the right groove wall 3b), and when it touches the right groove wall 3b, it is driven to the left (right groove wall 3b). Front wall 3b
drive leftward in the direction away from the Thereby, even if the right groove wall 3b is curved in the middle, it can be made to follow the curve.

(9) After running for a predetermined time (or for a predetermined distance), stop the drive.

(10) Next, by driving leftward in the Y-axis direction and repeating the above operations, rectangular oscillation welding that follows the groove 3 is realized.

FIG. 8 is an enlarged view of the state (state (4) above) when the vehicle is driven to travel in the X-axis direction along the left groove wall 3a. Left sensor probe 25
When it touches the left groove wall 3a, the Y-axis direction is corrected in the direction away from the left groove wall 3a, and when it moves away from the left groove wall 3a, the Y-axis direction approaches the left groove wall 3a. Correction control is performed in the direction. In this case, the design conditions for the scanning speed are: V _y > V _x V _x : Traveling speed in the X-axis direction V _y : Correction speed in the Y-axis direction, for example, V _x : 10 to 5 cm/min V _y : 30 to 80 cm/min It's fine if it's a minute. Further, the permissible amount of copying may be expressed as ΔY<ΔX ΔY: amount of change in the Y-axis direction ΔX: amount of change in the X-axis direction. Further, to prevent hunting, a hysteresis S _y of about 1 mm (1 mm when turning from on to off, 0.1 mm when turning from off to on) may be provided.

〔Effect of the invention〕

As described above, according to the present invention, copy welding using rectangular oscillation can be realized by switching between four drive controls. When the contact is moved along the groove wall, it moves away from the groove when it touches the groove, and when it leaves, it touches the groove. It can be imitated accurately.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of the mechanical part of an automatic welding device for carrying out the present invention, Fig. 2 is a side view of the device shown in Fig. 1, and Fig. 3 is a front view of the device shown in Fig. 1. 4 is an enlarged view of the sensor probe in FIG. 1, FIG. 5 is a diagram showing an embodiment of a control device for carrying out the present invention, and FIG. 6 is an example of the trajectory of automatic tracing welding according to the present invention. FIG. 7 is a flowchart for performing the welding shown in FIG. 6, and FIG. 8 is a diagram showing control on the side wall 3a of FIG. 6. 1... Welding torch, 2... Base metal, 3... Bevel,
3a, 3b...Grove wall, 4...Dolly, 6...Travel motor, 8...Transverse motor, 13...Electrode, 15
... Filler wire, 25, 26 ... Sensor probe, 27 ... Distance adjuster, 62 ... Travel distance detector, 70 ... Touch detection circuit, 71 ... Microcomputer.

Claims (1)

[Scope of Claims] 1. A welding torch is supported by a traveling drive means for traveling in the longitudinal direction of the groove and a traveling drive means for traveling in the width direction of the groove, and on both left and right sides near the electrode of the welding torch. This is an automatic arc welding tracing method in which two contacts that move together with the welding torch are arranged, and the touches of these left and right contacts on the left and right groove walls are detected respectively, and the welding torch is made to trace the groove. , a first drive control in which the travel drive means is stopped and the traverse drive means is driven leftward; and the travel drive means is driven forward and the traverse drive means is driven when a left wall touch is detected. a second drive control for driving rightward and driving leftward when a touch on the left wall is not detected; and a third drive control for stopping the running drive means and driving the traverse drive means rightward; a fourth drive control in which the travel drive means is driven forward, and the traverse drive means is driven leftward when a touch on the right wall is detected, and driven rightward when a touch on the right wall is not detected; In addition, when a touch on the left wall is detected while the first drive control is being executed, the switch is switched to the second drive control, and while the second drive control is being executed, the second drive control is switched to the second drive control. When the vehicle has traveled a predetermined distance from the start, it switches to the third drive control, and when a touch on the right wall is detected while executing the third drive control, it switches to the fourth drive control. A tracing method for automatic arc welding, characterized in that when the fourth drive control has traveled a predetermined distance from the start of the fourth drive control during execution, switching to the first drive control is performed.