JPS61293675A - Method for controlling weld line profiling - Google Patents

Abstract

PURPOSE:To uniformly weld even if the shape of welding zone varies by controlling the amplitude in weaving so that the electric quantity is convergent to the prescribed reference value by enabling to control the weaving amplitude according to the electric quantity of a welding arc. CONSTITUTION:The reference current at each point of PA, PB, PC is found by the formula by incorporating the designated welding voltage, welding current and extension length. Whether the torch is located at the position of PB is then judged and in case of being located at the PB position, the correction quantity ZB in the direction Z is found by the formula from the difference in the reference current and the obserbed current at the PB. In case of the torch being located at the PA or PC, the correction quantity X4, XC in X-Y direction is found by the formula from the difference in the reference current and observed current. The value in the X-Y direction is then found by the calculation of (PA+PC)/2 and the correction quantity in the X-Y direction of PB is taken as XB. The correction quantity in each X-Y-Z direction of PA, PB, PC is then added to the value of the position of PA, PB, PC, the conversion of the coordinate system is performed to output to each axis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for controlling automatic welding equipment, and particularly to a method for controlling weaving of a welding torch using a welding robot.

[Background of the invention]

In automatic bath welding using an industrial robot, the welding torch is moved along a welding line that has been taught in advance to proceed with welding. There is a risk that the welding torch may be misaligned due to changes in the shape or position of the workpiece (welding member).

Therefore, conventional methods have been to weave the welding torch (move the welding torch along the bath tangent by degrees Celsius and swing it from side to side in a direction perpendicular to the bath tangent), and then change the current 1 flowing through the welding torch or the voltage of the welding torch. A bath tangential tracing control method is used which detects the base of the heat and thereby ensures that the welding torch is always in the correct position. Note that such a weld line tracing control method is disclosed in, for example, Japanese Patent Publication No. 11502/1983.

By the way, in the case of workpieces to be butt welded, if there is a change in the opening angle or shape of the butt part of the workpiece, the welding conditions will change, and if welding is carried out ignoring this, the welding result will not be uniform. This results in variations in the strength and appearance of the welded part.

However, in the conventional weld line tracing control method described above,
This method merely corrects the positional deviation of the welding torch, and does not take into account any control that corresponds to changes in the shape of the welded part of the workpiece.

Therefore, conventionally, the operator carefully considered the shape of the workpiece in advance and adjusted the weaving amplitude each time.

Uniform welding results must be obtained by determining welding conditions such as cycle and torch angle.For this reason, conventional methods require a high level of skill to perform the work, yet still cannot produce sufficiently uniform welding results. The problem was that it was difficult to obtain.

[Purpose of the invention]

The present invention was made against the above-mentioned background, and its purpose is to automatically respond to changes in shape of the welded part of the workpiece and to always achieve uniform welding results. K provides a weld line tracing control method that achieves this.

[Summary of the invention]

To achieve this objective, the present invention detects the amount of electricity of the welding arc at the maximum amplitude position when weaving the welding torch, and controls the weaving amplitude so that this amount of electricity converges to a predetermined reference value. It is characterized by the fact that it is made to do so.

[Embodiments of the invention]

Here, the above-mentioned weaving will be explained.

This weaving is a technique used in conventional welding line tracing control, and is adopted when the welded part of the workpiece is a groove butt, as shown in Figure 2 and K3. The torch 1 is moved as PA-PB-Pc-PB-PA along the surface of the groove abutting portion of the workpiece 2, so that the position 11P at the center moves along the weld line.

In these figures, W represents the amplitude of weaving, Wo represents the direction of weaving, and t represents time.

Then, each time the bath welding torch 1 reaches the positions PA and PB, the above-mentioned amounts of electricity, such as the arc voltage and arc current of the welding torch, are collected and withdrawn, and the amount of electricity at the position P and the amount of electricity at the PC position are collected. By controlling the position of the welding torch 1 in PR so that the values are equal, tracing control is obtained.

At this time, if the shape of the groove abutting part of the workpiece 2 changes and changes from the shape shown in Figure 4 to the shape shown in Figure 4 or (O), in this conventional method, the weaving amplitude W
Since the welding wire is constant, the leg length of the welding result becomes defective, making it impossible to obtain uniform welding results.Especially in the state shown in figure K4 (Q), the welding wire does not aim at the surface of the workpiece groove, and tracing control is also impaired. It becomes possible.

Therefore, in the present invention, the following steps are taken.
Assuming that the arc voltage of the welding torch is controlled at a constant voltage, the relationship between the current (arc current) Iw flowing in the bath welding torch and the arc length ZE of the welding wire is Z, = 2, I, 2・・・・・・・・・・・・
...There is the relationship (1). Here, K1. and are constants, of which 1 takes a negative value.

Therefore, the current Iw and the arc length Z. It is inversely proportional to melting, and if you know the electric current, you can find the arc length Z! In other words, since the length of the welding wire extension can be determined, control is performed to keep the arc length constant at 2 degrees.

Next, as shown in Figure K5, assume that the opening angle of the workpiece with the ■-shaped groove changes. Here, it is assumed that the deviation in the vertical and horizontal directions is (, and the groove angle of the workpiece has changed from the standard shape of FA-P, -Pc to P/, -PB-P'. The amplitude of weaving in Fig. 5 is changed from Wl in the standard state to K according to the change in the groove angle.
Assuming control to change the value to 2, calculation of the correction amount W,1 required in this case will be explained.

First, the arc length during welding and the current value I at that time.
There is a relationship between (Equation 11) between w and w. Therefore, the position PC determined from the teaching point by teaching or it and the weaving amplitude is
As a result, if the arc length changes by 21 from equation (1), then K becomes ZE-)-Z1==1XI, □+, -...
・---・T2), and the actual flowing current value IW□
Therefore, the position of PCT is determined by (Z K + Z 1 ) (2. is the position at the time of teaching and is assumed to be known in advance). Also, the difference 2 in the height direction can be found from the position of P and the position of PC. Directly below the PC,
If T is the intersection of P with the horizontal direction, triangles P, -Pc, and -T can be created by the length of 2, which is (2-21),
P of p, -PC'r. Extension line in T direction and P.

P'o can be found from the intersection in the height direction Z from .

Also, triangle PB-PcT-T and triangle P, -P/.

-8 is similar. Therefore, W,/(2Z2) = (Wl/2+W11 t )/Z ・・・・・・
...The relationship is as shown in (3), W B 1 =Z X W x / (2Z z )-
w s / 2 ・・・・・・・・・・・・(4)
Yotsu, weaving amplitude correction 11W8. is found.

If this calculation is also performed on the PA side, the overall weaving amplitude is w, = w, +ws, +ws2 −−−−・−−−・・
- (5), and the amount of correction of the weaving amplitude can be calculated from the current value.

Next, one embodiment of the present invention will be described. The basics of the method of controlling the weaving amplitude in this example is as follows:
As shown in FIG. 6, the positions PA and PC control the horizontal direction, and the position P controls the vertical direction.

FIG. 1 is a flowchart in an embodiment in which the present invention is applied to actual weld line tracing control. First, in step 10,
The welding voltage, welding current, and extension length specified from the outside are taken in and out. Based on these three elements, pA, pB,
Find the reference current at each point p. The reference current to be found is, for example, I, = KLXL + KAXI + KvXV + Kc...
・・・・・・・・・(6) K becomes. Here, KL...Extension length coefficient, L...Specified extension length,
KA... Coefficient of welding current, Kv... Specified welding current, Kv... Coefficient of welding voltage, ■...
...Specified welding voltage, Kc...Constant
It is. In step 12, it is determined whether the person is at position P, and if gtK is at position P, then in step 14,
Based on the difference between the reference current (obtained in step 10) and the actually measured current at the PR position, the two-direction correction amount is obtained from the relationship of equation (1) (Z shown in the seventh position). Next step 1
6, PA or P. Determine whether you are in the position of PA or P. When you are at the position, in step 18, from the difference between the reference voltage R (obtained in step 10) and the actual measured current, (Equation 11.

Calculate the amount of correction in the X-Y direction from the relationship in equation (4) (7th
X A I X C) shown in Figure (b). In step 20, the values of the positions of PA and PC obtained in step 18 in the X-Y direction are obtained by calculating (PA+PC)/2, and this is used as the amount of correction of PB in the X-Y direction. (@Figure 7 (X shown in Q)) In step 22, the PA obtained in step 14, step 18, and step 20.

The amount of correction in the x-y-z direction for each position of PB and PC is PA,
Add to the position values of PB and PC. In step 24, the coordinate system is transformed, and in step 26, it is output to each axis.

If it is determined in step 28 whether or not to continue the weld line tracing control, the process returns to step 10.

The rJcB diagram shows the change in weaving amplitude in one embodiment of the present invention.
, fc) are shown in FIG. 4 (A) and (Bl.

(Each corresponds to O.) A thorough comparison shows that by implementing the present invention, weld line tracing control becomes effective regardless of changes in the groove shape of the welded member.

Next, FIG. 9 shows changes in the amount of bathing in the case of one embodiment of the present invention and the case of the conventional example.

If you look at L1/L6 in each figure, you can see that there is a large change in B1 in the conventional example compared to the standard (5). It can be seen that tO and a3 in the example case are almost the same as in the prisoner's standard case.

By the way, in the above embodiments, the butt groove shape of the workpiece is V-shaped, but it goes without saying that the present invention is not limited to this and can be implemented, for example, as shown in FIG. 10, (B) Even in the case of a groove shape as shown in , to,
As shown in FIG. 11(A), (El, (Q), it is possible to always control the weaving amplitude to an appropriate weaving amplitude w1.W,,VV, and easily obtain a uniform welding result.

In addition, in this embodiment, as is clear from FIG. 1, processing for welding line tracking control and processing for weaving S width control are performed separately, and finally, the correction amounts of both blades are combined. It is designed to control the movement path of the robot.

Normally, the welding line tracing control method involves keeping the welding wire length of the welding torch constant based on the amount of electricity applied to the welding torch's arc, and controlling the welding torch to move along the welding line, but weaving amplitude control is also used. When adding , the amount of electricity inevitably changes, making it difficult to control the welding line path.

Therefore, in the above-mentioned embodiment, a method was adopted in which the welding line follow-up control and weaving amplitude control were performed separately in consideration of this.1 As a result, according to the above-mentioned embodiment, the control process was simplified. , and can easily obtain accurate control.

〔Effect of the invention〕

As explained above, according to the present invention, the weaving amplitude is automatically controlled according to the shape of the abutting part of the work. It is possible to always provide uniform welding results even for such workpieces.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing an embodiment of the welding line tracing control method according to the present invention, Figs. 2 and 3 are explanatory diagrams of weaving, and Figs. 4 (8) to (q are explanatory diagrams of groove angle changes). , FIG. 5 is an explanatory diagram of the principle of weaving amplitude control in one embodiment of the present invention, FIG. 6 is an explanatory diagram of weaving amplitude control in one embodiment of the present invention, and FIG. An explanatory diagram of the groove shape, Fig. 8 - (Q is an explanatory diagram showing a weaving amplitude change according to an embodiment of the present invention, and Fig. 9 - 1 is an explanation of welding results obtained by an embodiment of the present invention) Figure 10 (0) is an explanatory diagram of weaving when the groove shape of the workpiece is different, Figure 11 (Q) is an explanatory diagram of weaving when the groove shape of the workpiece is different. It is an explanatory diagram of weaving amplitude control according to an embodiment. 1... Welding torch, 2... Workpiece. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 117 Figure (A) B 1 day) (C) Figure 118 Country 10

Claims (1)

[Scope of Claims] 1. In a weaving-type tracing control method in which tracing control is performed on a welding line by comparing the amount of electricity of a welding arc when the welding torch is at one of the maximum weaving positions and the other, the weaving of the welding torch is A means for controlling the amplitude according to the amount of electricity of the welding arc is provided, and the weaving amplitude of the welding torch is controlled so that the amount of electricity of the welding arc converges to a predetermined reference value. Welding line tracing control method. 2. The welding line tracing control method according to claim 1, wherein the quantity of electricity of the welding arc is at least one of an arc voltage and an arc current.