JPS5985371A - Arc welding method - Google Patents

Abstract

PURPOSE:To execute a follow-up of a weld line by providing an alternating magnetic field, vibrating an arc in the left and right directions being orthogonal to the weld line, detecting and comparing an arc current or voltage of the left and right of the vibration, and controlling a torch position so that its deviation becomes zero. CONSTITUTION:AC is impressed to an iron core coil 38 through an amplifier 42 from a generating circuit 40, an alternating magnetic field is formed in the direction of a weld line in the vicinity of an arc 22, and the arc 22 is vibrated in the direction orthogonal to the weld line. Subsequently, in accordance with an integration instruction and a storage instruction in a half period of an arc vibration which is outputted by a logic generating circuit 44 by an AC signal of the circuit 40, a detecting signal of an arc current by a shunt 26 is inputted alternately to storing circuits 30, 32, is integrated and stored, it is subtracted by a differential amplifier 34, and a signal corresponding to a shift of the vibration center is obtained. As a result, a direction of the shift is discriminated by a motor controlling circuit 36, and a motor 4 is controlled so that the shift becomes zero. In this way, the automatic follow-up of the weld line of a torch can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding method, and particularly to an automatic weld line tracking method using the welding arc itself as a sensor in arc welding.

Conventionally, there has been a device shown in FIG. 1 as a device for implementing this type of automatic weld line tracking method using the welding arc itself as a sensor.1 In the first, the welding torch IO is supported by an oscillator 12, is that nut part 1
(2a is screwed and supported on the threaded rod 14a of the moving device 14)
reactor. Therefore, the motor 16 moves the screw 14a to the rotating part 1i! ? The motion oscillator 12 pulses in the direction perpendicular to the welding line, and moves the welding torch 0 in a direction perpendicular to the welding line.
vibrate to the right. The tip of the above welding 1--chi 1o, !
'The consumable wire I8 protruding from the welding work 2o and the welding wire 1
They are placed opposite each other with a gap between them, and a welding arc 22 is generated in this gap to form a weld bead 24 for welding. A shunt 26 detects arc current. The switching circuit 28 is the oscillator 12
In response to the oscillation position signal from the shunt 26, the detection signal from the shunt 26 is alternately distributed to the detection storage circuits 30 and 32 for each left and right half cycle of vibration of the welding torch 10. The detection storage circuits 30 and 32 detect and store the maximum value and average value of the detection signal of the shunt 26 for each half cycle. A differential amplifier circuit 34 compares the outputs from the detection storage circuits 30 and 32. The motor control circuit 36 controls the motor 16 so that the output of the differential amplifier circuit 34 is always zero.
It controls the

The conventional apparatus for carrying out the automatic welding line tracking method has the above-mentioned structure, and its operation will be explained next. The welding wire 18 is fed at a constant speed while the welding torch 10 is vibrated in the left-right direction perpendicular to the welding line by the moving device 14 and the motor 16 via the oscillator 12, and a welding wire is created between the welding workpiece 2o and the welding wire 18. 22 is generated, a weld bead 24 is formed, and the welding workpieces 20 are joined. At this time, welding torch 1
When the zero imaging center is at the correct position, the arc currents on the left and right sides of the vibration will be equal; if it is shifted to the right, the arc current will be on the right side of the vibration, and if it is shifted to the left, the arc current will be on the left side of the vibration. Utilizing the principle of increasing scale, the welding current signal detected by the shunt 26 is detected and stored every half cycle of welding torch photography by the switching circuit 28 based on the oscillated position signal of the onrator 12. circuits 3o and 3
Alternately divide into 2. These detection storage circuits 3o and 3
In step 2, detect the maximum value or average value for each half-cycle taken separately and record this value in step 4. The output from both circuits is reduced by the differential amplifier 34 by 3? , a signal corresponding to the deviation of the center of vibration can be obtained. The direction of the deviation is determined by the motor control circuit 36, and the motor 16 is controlled to follow the welding line so that the signal corresponding to this deviation is always zero.

The arc itself in conventional arc welding is seven times smaller.

- A device for implementing the automatic tracking method of a closed welding line Since the method is configured as above, the welding torch must be mechanically vibrated, a mechanical oscillator device is required, and the welding head rotation Not only is it complicated and heavy, but depending on the groove shape of the welding workpiece, such as narrow gap welding, it may be physically difficult to vibrate the welding torch. There was a drawback that it could not be done. However, since it detects the average value rather than the maximum value for each half-cycle of arc current oscillation, it also has the disadvantage that the accuracy is not very good.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to enable a welding head rotation to be constructed easily and lightweight, and to allow the welding head to be easily and lightly welded, such as in narrow gap welding. Automatic tracking of the weld line using the highly accurate arc itself as a sensor, which can be applied to welding soaks in grooves where there is not enough room for movement, as long as there is a minimum amount of room to mechanically correct the welding torch position. The purpose is to provide a method.

In order to achieve the above object, the present invention forms an alternating magnetic field in the direction of the welding line near the arc in non-consumable electrode type DC arc welding where only two consumable electrodes are used to vibrate the welding arc in the left-right direction perpendicular to the welding line. The present invention is characterized in that the arc currents and arc voltages on the left and right sides of the vibration are detected and compared, and the position of the welding torch is controlled to follow the welding line so that the deviation becomes zero.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a configuration diagram of an apparatus for carrying out the method of the present invention, and the same parts as in FIG. The welding torch 10 is connected to the threaded rod 14al of the moving device 14.
An iron-core coil 38, which is directly attached to the movable table 14b and fixed to the tip of the welding torch, is used to form an alternating magnetic field in the direction of the welding line. The AC signal generation circuit 40 generates an AC signal such as a sine wave through an amplifier 42,
A supply voltage is applied to the logic generation circuit 44. This amplifier 42 amplifies the output from the AC signal generation circuit 4o and applies it to the iron-core coil 38. Still, the logic generation circuit 44 instructs the detection storage circuits 30 and 32 to integrate and store the signals based on the signal from the signal generation circuit 40.

The apparatus for carrying out the method of the present invention has the above-mentioned configuration, and its operation will be explained below. Signal generation circuit 4
By amplifying alternating current signals such as sine waves, triangular waves, and rectangular waves generated by 0 in the amplifier circuit 42 and applying them to the cored coil 38, an alternating magnetic field in the welding line direction is formed in the vicinity of the welding arc 22. The welding arc 22 generated between the welding wire 18 and the welding workpiece 20, which is being fed at a constant speed, undergoes FA movement in a direction perpendicular to the welding line under a force proportional to the strength of the magnetic field. This vibration of the welding arc 22 changes the arc length and the protruding length of the wire, and as a result, the arc current and arc voltage change. When the welding torch 10 is in the correct position, the arc currents on the left and right sides of the vibration are equal; when the welding torch 10 is shifted to the right, the arc current on the perturbed left side is higher than that of the vibrating cloth, and when it is shifted to the left, the arc current on the left side of the perturbation is higher. growing. Therefore, the shunt 26 detects the arc current.

On the other hand, based on the signal from the signal generation circuit 40, the logic generation circuit 4
A storage circuit 30 detects the detection signal of the shunt 26 in accordance with an Xfi command and a storage command for the entire period of a half cycle of welding torch vibration or a fixed period within the half cycle outputted from 4.
．． 32 alternately to integrate and store. Then, the motor control circuit 36 divides the direction of deviation by 1:1 so that the signal corresponding to the deviation obtained by subtracting this integrated and stored signal by the differential amplifier 34 is always zero.
6, the welding line is automatically tracked using the arc itself as a sensor.In the above embodiment, the welding torch 10 is provided with an iron-core coil 38, but an iron-core coil 38 is installed in the welding torch 10. In addition to 38, a hollow coil capable of forming a magnetic field may be used, and this may be supported by the moving device 14. In the above embodiment, the integral value of the arc current for the entire period or a fixed period of each half cycle of the left and right half cycles of welding arc vibration is detected. Voltage may also be detected. Still detection memory circuit 30, 32, differential amplifier circuit 34
, the signal processing by the motor control circuit 36, etc. may be performed by other devices having the same effect, such as arithmetic processing using a microcomputer.

In the above embodiments, the case of consumable electrode type DC arc welding has been described, but the same effects as in the above embodiments can be obtained even in the case of non-consumable electrode type DC arc welding.

As described above, since the welding arc is vibrated by electromagnetic force in the present invention, there is no need for a mechanical oscillator device, and the configuration of the welding torch or Iyp can be simplified and reduced in number. Even in cases such as groove welding where the groove width is narrow and there is no room to vibrate the welding torch, the weld line automatic tracking method using the arc itself as a sensor can be applied. However, in the embodiment, the integrated value of the arc current for a certain period is detected and compared, and the position of the welding torch is adjusted so that the deviation becomes zero. 1 and 1'', effects such as being able to follow the weld line with high accuracy can be obtained.

[Brief explanation of the drawing]

2jf, Figure 1 is a block diagram of a system implementing the conventional automatic welding line tracking method using the welding arc itself as a sensor, and Figure 2 is a welding line diagram using the welding arc itself as a sensor according to the present invention. This is a borrowed diagram of a device that implements the automatic tracking method.The middle part of each figure is labeled with the same number, 1o is a 4-I contact torch, 12 is an oscillator, J4 is a transfer jl! II device,
16 is a motor, 18 is a consumable wire, 2o is a welding work,
22 is a welding arc, 24 is a welding bead, 26 is a shunt,
28 is a switching circuit, 30.32 is a detection storage circuit, 34 is a differential amplifier circuit, 36 is a motor control T111 circuit, 38 is a coil with iron core, 4o is a direct 6ft, signal generation circuit, 42 is an amplifier, 44 is a logic generator It is a circuit. Agent: Patent attorney Shin Kuzuno - (1 person) Figure 1 Figure 2

Claims (1)

[Scope of Claims] (1) In consumable Wc electrode type or non-consumable electrode type DC arc welding, an alternating magnetic field in the direction of the welding line is formed near the arc to vibrate the welding arc in the left and right direction orthogonal to the welding line, An arc welding method characterized by detecting and comparing arc currents or arc voltages on the left and right sides of the vibration, and controlling the position of a welding torch to follow a welding line so that the deviation becomes zero. (2) In the method according to claim (1), an alternating current is applied to a magnetic field generating coil provided near the welding arc to form an alternating magnetic field in the welding line direction near the welding arc. An arc welding method characterized by vibrating the welding arc. ; An arc welding method in which the percentage sign is to detect and compare the maximum value or minimum value for each half cycle of left and right vibrations of pressure. (4) Claims (tl) In any method of (2) An arc welding method characterized by detecting and comparing the integral value of the arc current or arc voltage caused by the vibration of the welding arc over the entire period or a fixed period of each of the left and right half cycles of the vibration.