JPS60154878A - Arc welding method - Google Patents

Abstract

PURPOSE:To increase considerably a welding speed and to enable welding of thin sheets in profiling arc welding in which the weld line is detected and guided by a change in the current in the groove part in weaving welding by detecting intermittently the weaving position of an arc. CONSTITUTION:The weaving arc welding having a limit in a progressing speed is intermittently accomplished and a torch is guided by detecting the position in weaving arc welding in which the weld line is detected from the change in the period and current owing to weaving of a torch with respect to a groove part and the torch is guided. The progressing speed of welding is increased in the non-weaving stage. The overall welding speed is considerably increased by such combination and the groove welding of thin sheets is made possible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an arc welding method, and more specifically, to detecting the groove position of a weld joint in an automatic arc welding method that proceeds along the weld line direction. The present invention relates to an arc welding method in which the movement of the arc itself can be made to follow the welding line direction of a joint portion without using a sensor.

[Background of the invention]

Automatic arc welding equipment is intended to be unmanned due to poor working conditions at the welding location, but in order to be unmanned, it is necessary to avoid misalignment of the weld line (groove line) of the welded joint, which changes from moment to moment during welding. A detection sensor for automatically detecting and controlling the torch position and a torch position adjustment mechanism that operates based on the sensor are required.

Conventionally, this type of detection sensor is generally known to include a sensor that detects the position of the torch tip and the weld line position, and to control the position of the torch in accordance with the sensor output. In addition to this, there are also ACs that have a sensor function on the arc itself.
There is a C (arc current control) method. This method involves waving the arc and comparing the arcs at the left and right ends of the weld to detect a shift in the center of the weld. Since this method constantly oscillates the arc, there is a limit to the welding speed, and it has been difficult to apply it to thin plate welding, which requires a relatively high welding speed.

In other words, for thick plates (5 to 12wn), good welding can often be achieved by applying rocking motion, so an AC that senses the necessary signals from the rocking motion is necessary.
There is no problem in carrying out method C, but if the object to be welded is a thin plate (4 to 1 m), if the arc is oscillated, the welding speed will drop excessively, causing problems such as making holes in the welded part. can be,
At present, this arc swinging force type cannot be adopted.

[Object of the invention] The object of the present invention is to solve the problems of the prior art described above,
It is an object of the present invention to provide an arc welding method that enables accurate and rapid tracing control using the arc characteristics of the arc itself, and that can perform good welding even on thin plate materials.

[Summary of the invention]

The feature of the present invention is that in the ACC method, the arc generated between the base metal and the welding electrode is oscillated, the welding line is detected from the arc phenomenon obtained by the arc oscillation, and the welding line is arc welded along the welding line. The point is that the arc swing is performed intermittently.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1st
In the figure (-), the wire 3 from the torch 2 is the welding line P of the base metal 1.
FIG. 1(b) is a diagram illustrating the principle of ACC welding based on FIG. 1(a). That is, by swinging the torch 2 holding the wire 3 with respect to the base material 1 in directions a and b, the flow value of the welding portion 5 flowing through the wire 3 can be changed. In the figure, the center of the torch is on the welding line, and when the torch 2 swings symmetrically in directions a and b due to weaving, the welding current flowing through the wire 3 becomes as shown in the waveform diagram in Figure 2, and the weaving frequency behaves at twice the frequency of This is the current value Ia, I between the weaving end a and the end
b have equal values.

Figures 3 (a) and (b) are similar to Figure 1 (a) l (b)
FIG. 4 is a diagram corresponding to FIG. 2, and shows the state when the center of the torch 2 is off the welding line. In this case, when the torch 2 is oscillated, the welding current I
are asymmetrical, but the relationship between the weaving waveform and the welding current at that time is shown in FIG. 4, where the current values Ia and Ib at the weaving end a and welding end are different. A.C.
The deviation from the center of oscillation in C welding method VC is the current Ia,
ACC welding is realized by detecting Ib and controlling the trajectory of the center of the torch using a correction amount corresponding to the deviation as a control amount.

In this way, the ACC method uses wire 3, i.e.
This is done by oscillating the arc between tfl' and tfl' 1, detecting the change, and correcting the deviation, and it is considered essential to oscillate the arc. Generally, the deviation angle α between the weld line and the weaving center line is expressed by the following relational expression.

α: deviation angle (deg), V: welding speed (lel+/,,
c), T: weaving period (aec), K: follow-up constant Therefore, it can be seen that there is a limit to the welding speed that can be followed by ACC welding. Therefore, in the present invention, AC
This is a method in which the inevitable oscillation of CVc is selected and made to behave, and in a series of welds, welding is performed by following the welding line as in ACC.

The present invention is equipped with a function to turn on and turn off ACC welding when performing ACC welding and swinging, and these functions can be performed by pressing a button on a teaching pendant or by pressing a preset welding button. It is designed to be able to be turned on and off depending on the size, and ACC welding is performed partially. For example, when welding a base metal that has a straight weld line and a curved weld line, intermittent ACC welding can be performed by turning on and off the welding line at the dividing line.

FIG. 5 is a diagram showing welding using the arc welding method according to the present invention, in which ACC is turned on to apply oscillation to the arc at an arbitrary point Pn on the welding line, and turned off at point P'n. It's in control. Other welding lines are welded in a normal straight line. That is, ACC welding is performed only between points Pn and P'n.

Figure 6 shows a case where the weld line of the base metal has a straight part and a curved part, and the above-mentioned copy welding is performed in which the arc itself has a sensor function, and points P1 to PIO are ACC welding. indicates the point at which the ACC welding starts, and points P'1 to P'IO indicate the point at which the ACC welding ends. In other words, ACC welding is taught to be turned on at 21 points, and P'
Teach off at one point. P2 below for Mukai-sama
+ P2...Teach the intermittent point of ACC welding up to the P2O point. When welding is started after this teaching is completed, ACC welding is first performed between points PI and P'1,
The position of the torch is corrected while detecting the deviation of the welding line. Then, I'1 ACC welding is turned off between points p'1 and p2, and welding is performed under high-speed welding conditions without arc fluctuation. Thereafter, welding up to point P'lO is completed while partially performing ACC welding in the same manner.

According to the generally known ACC welding method, the maximum welding speed is 300 Wa/'min-4 under the conditions of a groove of 90°, a target of 45°, a weaving frequency of 2 Hz, and a deviation angle of 5°.
According to the ninth embodiment of the present invention, the welding speed is 2 to 3 times higher, and there is no problem in welding strength.

In addition, for thin plate welding and welding methods that require precision,
Generally, weaving welding in which the arc is oscillated is not performed, but in this case, copy welding using the known ACC method cannot be applied. According to this embodiment, the minimum ACC detection location is taught depending on the base material, workpiece precision, and welding conditions, and it can be said to be optimal for ACC copy welding of that portion.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention, the arc is oscillated intermittently along the welding line. According to this ACC copy welding, the welding speed is significantly improved compared to the conventional welding method. Therefore, it is particularly suitable for thin plate workpieces.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing the positional relationship between the torch and the base material;
Fig. 1 (b) is a diagram for explaining the ACC welding principle, Fig. 2 is a waveform diagram showing the welding current and arc fluctuation state, and Fig. 3 is a diagram for explaining the ACC welding principle.
Figure (a) is a perspective view showing the positional relationship between the torch and the base metal in the gap where the welding line is misaligned, Figure 3 (b) is a diagram to explain the ACC welding principle at that time, Figure 4 FIG. 3 is a waveform diagram showing the welding current and the oscillating state of the arc in the case of FIG. 3, and FIGS. 5 and 6 are a perspective view of a base material and a welding line diagram for explaining the bath welding method of the present invention. 1... Mother phase, 2... Torch, 3... Wire, P1
~PIO...Arc swing starting point, P'1~P'1o・
...Arc swing end point. Agent Patent Attorney Tadashi Akimoto Figure 1 (a) Figure 2 Figure 3 (a) (b) Figure 4

Claims (1)

[Claims] A copying arc welding method in which an arc generated between a base metal and a welding electrode is oscillated, a weld line is detected from the arc phenomenon obtained by the arc oscillation, and arc welding is performed along the weld line, the method comprising: An arc welding method characterized by intermittent rocking.