JPH01210170A - Arc welding method - Google Patents

Abstract

PURPOSE:To make welding highly speedy and to stabilize sensing by executing welding by partitioning it in a welding stage and sensing stage, moving a welding torch along the weld line at welding stage and rocking it at sensing stage. CONSTITUTION:A head 6 is formed by executing an arc welding by setting a weld line 2 on a welding work 1. In this case, the welding process is set by sectioning it in welding stage and sensing stage and also the movement state of a torch optimum for performing the weld line detection, welding current, welding voltage and the duration of both stages are set. An arc sensing operation is performed at one unit at the preceding position of an arc point locus 4 for sensing and in succession the welding along an arc point locus 3 is executed by stopping the rocking. The welding conditions range is thus enlarged and profile welding is made highly speedy. The sensing is stabilized because it is executed by separating from the welding conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a t-arc welding method using an arc sensor.

Conventional Technology In order to automate the arc welding process, it is necessary to automatically correct errors in tacking arc welding workpieces, errors in fixing the workpieces to the workbench, errors due to thermal distortion during welding, etc. It won't happen. For this purpose, a position sensor is required that detects the deviation of the current position of the joint with respect to the welding line that is previously taught to the automatic welding machine.

Conventionally, various position sensors have been devised, one of which is an arc sensor that uses the welding pattern itself as a sensor.

The most common arc welding power source is a power source with constant voltage characteristics. This type of power source has an arc characteristic in which the arc current and voltage change as the arc length changes. On the other hand, since the joint to be welded has some shape change, the area arc length changes due to this shape change, so the current,! Pressure changes. Therefore, by observing these welding currents and welding voltages, changes in the shape of the workpiece can be determined.

Problems to be Solved by the Invention The principles of the arc sensor are as follows; however, in reality, there are various noise components and it may not be possible to clearly obtain the changes in the current and voltage. This is particularly likely to occur when the change in shape of the workpiece is small, such as workpieces made of stacked thin plates.

Another problem is that the welding arc phenomenon itself is not stable, and for example, welding may have to be carried out in a current range where short-circuit transitions occur frequently.

Therefore, it is an object of the present invention to provide a method to solve the above-described problem M, to be able to reliably remove noise components, and to perform sensing in a stable state.

Means for Solving the Problems The present invention detects changes in at least one of the welding current and the welding voltage by swinging the welding torch in a direction across the welding line during welding. Therefore, when determining the relationship between the workpiece joint and the arc generation position, it is possible to determine the welding process under the specified arc welding construction conditions and the specified detection conditions required by the workpiece shape and welding power source. and a sensing step that operates ninthly to detect the weld M, and the desired torch motion shape, welding current, welding voltage, welding speed, and connection of each of the two steps to detect the welding line. The time is judged and determined, and follow-up welding is performed by repeating these two steps alternately at appropriate durations.

Further, according to the present invention, in the welding process, the welding torch moves along the welding line without swinging in a direction across the welding line, and in the detection process, the welding torch performs the above-mentioned swinging.

Further, the present invention has a predetermined transition step for smoothly changing the welding current and welding voltage, which are different from each other in both steps, when changing from the welding process to the detection process, or conversely from the detection process to the welding process.

With this method, the bath welding work is interrupted at key points, and during that time the welding line is detected or sensed using the welding current and welding voltage. That is, sensing by the arc sensor is performed under conditions in which the arc sensor exhibits its full performance, and arc welding is performed under conditions that best satisfy the required working conditions. Therefore, stable t-sensing is performed under any welding conditions.

When changing the process, the welding current and welding voltage, which are different from each other in both processes, are designed to have a predetermined transition process that smoothly changes, so that the connection between the two beads is smooth. Become.

Example Fig. 1 shows the changes in the fluctuation component of the welding current when the welding current is used as a variable! I is schematically shown.

From the figure, it can be seen that the arc phenomenon is relatively stable in the low current region amat and in the spray region C, which is a large current region. On the other hand, in the short-circuit transition fecundity wcb, which is a medium current region, the stability of the arc is not so good.

In the present invention, the welding current is narrowed to a small value, and the above-mentioned low current region vt
, a are used for sensing. Of course, the conditions automatically determined as mentioned above, and some of the conditions,
The operator may teach it each time. If you do this,
The operation is a little more complicated, but you can freely set the conditions instead.

FIG. 2 shows a specific example of the present invention applied to a T-joint. Almost the same thing can be said about other joints.

In FIG. 2, 1 is a welding workpiece, which has a line 2 to be welded. 3 is the arc point locus along line 2, which is moved under the welding conditions required for this joint. As a result of welding, a bead 6 is formed.

4 is the t-th arc point locus of the sensing operation. At a position t a little ahead of the formed bead 6 in the direction of welding progress, one basic unit operation of arc sensing operation by conventional weaving is performed.

That is, the arc point is moved in the direction across the weld line 2. At this time, by making the welding current and welding voltage sufficiently low, the influence on the beats 6 finally obtained under the required welding conditions is small and can be ignored.

Also, in the low current range of t1, stable t sensing can be performed.

After one unit of sensing operation, welding is performed under the same conditions as in the case of re-hearc point locus 3. All five arc point trajectories at this time are shown. At this time, the starting position of trajectory 5 is set to trajectory 3.
By setting it close enough to the end position of , you can connect two beads and kill it. In order to create a smooth IC through the connection between the two beads, the welding conditions must be changed smoothly at the boundary between trajectories 3 and 4 and between trajectories 4 and 5, that is, at the boundary between the welding part and the sensing part. In some cases, it is better to include a transition process.

Below 1. These welding steps and sensing steps may be performed alternately. Normally, the thinner the workpiece is, the less thermal distortion there will be. Also, the setting error of the work,
In reality, it's not that big. Therefore, in many cases, it is required to have a relatively low ability to follow deviations from the taught trajectory, and instead weld at high speed. All the wards till? If arc sensing is used during weaving welding, the overall welding speed will be suppressed by weaving, but in the present invention, the ratio of the length of the welding part to the sensing part can be set freely, so it can be specified in advance during teaching. By doing this, ordinary weaving welders can take advantage of faster straight line welding.

According to the present invention, by determining the ratio between the welding part and the sensing part in advance during teaching, it is possible to decide whether to emphasize the follow-up ability or the welding speed independently of the welding conditions. Out.

In addition, since the arc sensor uses the welding phenomenon itself,
In the conventional method of performing arc sensing at the same time as weaving welding, it was necessary to delicately adjust the ability and stability of the sensor under the required welding conditions, but in the present invention, the welding process Since the sensing process and sensing process are completely separate, sensing is not affected by welding conditions.

The third control device for welding and sensing is equipped with a CPU, and its configuration is not shown because it is well known. R backed up by battery as memory
The sensing conditions are optimal for this memory, i.e. the motion pattern of the arc point.

Stores welding current, welding voltage, and welding speed. Further, these sensing conditions, required welding conditions, and follow-up ability are stored as a tape /L"i, which outputs the ratio of the welded portion to the sensing portion.

By using this tape /L/'6, the operator does not have to consider the combination of sensing conditions and welding conditions. In other words, it is sufficient to perform the same operation as in teaching normal welding conditions.

Effects of the Invention According to the present invention as described above, the welding work is cut into pieces at key points and the weld line is detected during that time, so that the following effects can be obtained.

■ Regarding the relationship between the tracking ability of the arc sensor and the welding speed, the range of conditions has been expanded compared to before, making it possible to perform high-speed profile welding.

■ Because sensing conditions are separated from welding conditions,
Stable sensing becomes possible.

■ There is no need to weave during welding.

(2) When changing the process, it is possible to smoothly change the welding current and welding voltage, which are different from each other in both processes.% The connection between the two beads can be made smooth.

[Brief explanation of the drawing]

The example drawings are for explaining an arc welding method based on one embodiment of the present invention. Figure 1 is a diagram schematically showing the variation ratio with respect to the welding current, and Figure 2 is a diagram showing the variation ratio of the arc welding method based on the method of the present invention. / FIG. 2 is a perspective view showing a bead portion of a T-joint workpiece. 3...Low current region, 2...Welding line, 3.5...Welding part, 4...Sensing part. Agent Yoshihiro Morimoto Figure 1 Odd a - Low current circulation area

Claims (1)

[Claims] 1. The welding torch is oscillated in the direction across the welding line during welding, and a change in at least one of the welding current and welding voltage is detected, so that the arc between the joint of the workpiece and the welding voltage can be detected. When determining the relationship between the welding position and the welding position, the welding process is performed under predetermined arc welding construction conditions, and the weld line is detected under predetermined detection conditions required by the workpiece shape and welding power source. The desired torch motion form, welding current, welding voltage, welding speed, and duration of each of the two steps are determined by determining the desired torch motion form for detecting the weld line, and the duration of each of the two steps is determined. An arc welding method that performs follow-up welding by repeating the process alternately at appropriate durations. 2. The arc welding method according to claim 1, wherein in the welding step, the welding torch moves along the welding line without swinging in a direction across the welding line, and in the detection step, the welding torch performs the swinging. 3. Claim 1 or claim 3, wherein the welding process includes a transition process for smoothly changing the welding current and welding voltage, which are different from each other in both processes, when changing from the welding process to the detection process, or conversely from the detection process to the welding process. The arc welding method described in 2.