JPH0655272A - Consumable electrode type arc welding method - Google Patents

Abstract

PURPOSE:To improve followability of a weld line without generating meandering beads by making changeable the welding torch position correction quantity in the consumable electrode arc welding method where a welding torch is advanced along the weld line while being weaved on right and left in a groove having a V-shape, an L-shape or a shape similar to these and welding is performed. CONSTITUTION:When the correction direction for the weld line of the welding torch detected at a specified period based on a welding current is one side for the weld line, +K is set as the direction corresponding change quantity (u). When the correction direction is the opposite direction -K is set as the direction corresponding change quantity (u) and when the weaving center of the welding torch is coincident with the weld line, 0 is set as the direction corresponding change quantity (u) and the change quantity obtained by adding all of the direction corresponding change quantity (u) on the correction direction of the past specified times including this time is made to the present correction quantity U for the weld line of the welding torch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode type arc for performing welding along a welding line while weaving a welding torch left and right in a V-shaped, L-shaped or similar groove. The present invention relates to a welding method, and more particularly, to an arc welding method using a welding line automatic copying control that causes a welding torch to correctly follow the welding line.

[0002]

2. Description of the Related Art In automatic tracing control of a welding line, for example, a welding torch 1 is shown in the V-shaped groove as shown in FIG. 7 with left and right sides (left end is L, right end is R, and weaving center is O). It is common practice to use the relationship between the wire protrusion length and the welding current when weaving the wire. A method of this kind is disclosed in, for example, Japanese Patent Laid-Open No. 61
There is a technique disclosed in Japanese Patent Publication No. 144272.

In this prior art, as shown in FIGS. 8 (a) and 8 (b), the welding current waveform when the weaving center and the welding line coincide, and FIGS. 9 (a), 9 (b) and FIG. 10 (a),
As shown in (b), the fact that the welding current waveform is different when the weaving center does not match the welding line is used.

That is, in the weaving left-right scanning, the difference ΔIL = IL ₁ -IL ₂ between the maximum current value IL ₁ and the minimum current value IL ₂ during the process from the L end to the R end, and
Difference ΔIR = IR ₁ -IR ₂ between the maximum current value IR ₁ and the minimum current value IR ₂ in stroke from R end to L end, FIG. 8 (a), the
Using the fact that ΔIL = ΔIR in the state shown in FIG. 9B, ΔIL> ΔIR in the state shown in FIGS. 9A and 9B, and ΔIL <ΔIR in the state shown in FIGS. 10A and 10B. There is.

Therefore, if ΔIL> ΔIR, then FIG.
As shown in FIGS. 10 (a) and 10 (b), since the welding torch 1 is positionally corrected to the right by a predetermined fixed amount K while ΔIL <ΔIR, FIG. ，
Since it is in the right-shifted state as shown in (b), the welding torch 1
The position is corrected in the left direction by the predetermined amount K. Such a correction operation is performed every weaving half cycle so that the weaving center of the welding torch 1 automatically follows the welding line.

[0006]

However, in the conventional consumable electrode type arc welding method, since the correction amount of the welding torch position for one time is fixed to the constant amount K, there is a limit in the follow-up range and the target welding is performed. If the line changes abruptly or if the weaving center and the welding line deviate significantly, it is not possible to follow quickly. Further, if the value of the correction amount K for one time is extremely increased in order to widen the follow-up range, there is a problem that a meandering bead is generated.

The present invention is intended to solve such a problem, and consumable electrode type arc welding in which the correction amount of the welding torch position is made variable and the followability of the welding line is improved without causing a meandering bead. The purpose is to provide a method.

[0008]

In order to achieve the above object, the consumable electrode type arc welding method of the present invention is to weld the welding torch based on the welding current detected while periodically weaving the welding torch. In a welding system that corrects the position with respect to a line and follows the welding line, the welding direction of the welding torch is detected in a predetermined cycle based on the welding current, and the welding direction is the welding direction. If it is on the one side with respect to the line, a positive fixed amount is set as the direction correspondence change amount, and if the correction direction is on the other side with respect to the welding line, it has the same magnitude as the positive constant correction amount. A negative fixed amount is set as the direction correspondence change amount, and when the correction direction in which the weaving center of the welding torch and the welding line coincide is 0, 0 is set as the direction correspondence change amount. However, the sum of all the direction corresponding change amounts for the past predetermined number of correction directions including this time is set as the current correction amount for the welding line of the welding torch, and the position of the welding torch is moved by the current correction amount. It is characterized by doing.

[0009]

In the consumable electrode type arc welding method of the present invention described above, the current correction amount for the welding line of the welding torch is variable because it is the sum of the direction correspondence change amounts for the past predetermined number of correction directions including this time. In addition to increasing the scanning following range, even if an erroneous scanning signal is generated, it is averaged by the sum and the influence of the erroneous scanning signal can be suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A consumable electrode type arc welding method as one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart for explaining the correction amount determining procedure.
FIG. 2 is a flowchart for explaining the welding torch position correction procedure, FIG. 3 is a block diagram showing an arc welding apparatus to which the method of this embodiment is applied, and FIG. A table showing how the correction amount of this time corresponding to the correction direction of the previous time and this time becomes concrete, and FIGS. 5 and 6 are graphs showing the weld line followability when the method of this embodiment is applied. is there.

First, referring to FIG. 3, an arc welding apparatus to which the method of this embodiment is applied will be described. In FIG. 3, 1 is a welding torch, 2 is a work having a V-shaped groove 2a, and 3 is an arm tip. A welding torch 1 is attached to the portion, and a multi-joint type arc welding robot that performs welding on the workpiece 2 while controlling the position of the welding torch 1 is a robot control panel for controlling the operation of the arc welding robot 3. Is.

This robot control panel 4 has a V-shaped groove 2a.
A calculation for weaving the welding torch 1 to the left and right is performed, and each arm of the arc welding robot 3 is drive-controlled based on the calculation result to swing the welding torch 1 at a predetermined weaving frequency. Is.

Further, 5 is a welding power source for supplying electric power for arc welding, 6 is a shunt attached to the welding power source 5, and a welding current is detected from the shunt 6. The welding current detected from the shunt 6 is digitally converted by the A / D converter in the robot control panel 4, and based on the welding current digital value and the end signal indicating the weaving end used for the weaving operation, the robot control panel. 4, the position correction direction of the welding torch 1 and the correction amount for one time are calculated according to the flowcharts described later with reference to FIGS.
Is output to. As a result, the position of the welding torch 1 with respect to the welding line is corrected based on the welding current detected while weaving the welding torch 1 periodically, and welding is performed while following the welding line.

With the device constructed as shown in FIG.
In the present embodiment, according to the flowcharts shown in FIGS. 1 and 2, the welding line automatic copying control for causing the welding torch 1 to correctly copy the welding line is performed as follows.

First, referring to FIG. 2, a basic welding torch position correction procedure will be described. It is determined whether or not the welding torch 1 is in the transition section from the L end to the R end (step S1), and the transition is performed. If it is in the section, the maximum current value IL ₁ and the minimum current value IL ₂ in the transition section are sampled (step S2), while if it is not in the transition section, that is, the welding torch 1 moves from the R end to the L end. If it is during the transition section, the maximum current value IR ₁ and the minimum current value IR ₂ during the transition section are sampled (step S3).

When the half cycle of the weaving cycle is completed and it is determined that the weaving cycle is not the first half cycle (steps S4, S
5), the difference ΔIL = IL ₁ −IL ₂ between the maximum current value IL ₁ and the minimum current value IL ₂ during the process from the L end to the R end, and
Difference between the maximum current value IR ₁ and the minimum current value IR ₂ in stroke from R end to L ends .DELTA.iR = calculates the IR ₁ -IR ₂ (step S6). If the process for at least one cycle is not completed, the four current values IL ₁ , IL ₂ , IR ₁ , IR ₂ necessary for the calculation process after step S6 cannot be obtained, so the determination process at steps S4 and S5 is performed. Is being carried out.

After calculating these differences ΔIL and ΔIR,
The current correction direction and the current correction amount are determined by the correction amount determination processing described later with reference to FIG. 1 (step S7), and control commands based on these current correction direction and current correction amount are output to the arc welding robot 3. (Step S
8) The welding torch 1 is moved in the current correction direction by the current correction amount, and the weaving center of the welding torch 1 is automatically made to follow the welding line.

Next, referring to FIG. 1, step S7 described above is performed.
The procedure of the correction amount determination processing of this embodiment performed in step S6 will be described. First, the difference ΔIL calculated in step S6.
And ΔIR are compared (step A1), and the magnitude relationship is Δ
It is determined whether IL> ΔIR, ΔIL = ΔIR, or ΔIL <ΔIR.

When ΔIL> ΔIR, the correction direction is the right direction (R end direction) with respect to the welding line, and a preset positive fixed amount + K (mm) is set as the direction correspondence change amount u. If it is set (step A2) and ΔIL = ΔIR, the weaving center position of the welding torch 1 and the welding line position match, and 0 is set as the direction correspondence change amount u (step A3), and ΔIL If it is <ΔIR, the correction direction is the left direction (L end direction) with respect to the welding line, and a negative fixed amount −K (mm) is set as the direction correspondence change amount u (step A4).

In this embodiment, the present direction correspondence change amount u obtained in a predetermined cycle is used for the past two times, that is, the previous direction correspondence change amount u _OLD1 and the last two direction correspondence change amount u.
_{The value} added to _OLD2 is calculated as the current correction amount U for the welding line of welding torch 1 (step A5).

FIG. 4 shows an example of a concrete correction amount determination result by the correction amount determination processing procedure of the present embodiment described above with reference to FIG. However, in FIG. 4, L described in the column of correction direction before last time, previous time, and this time is when the correction direction is left direction, that is, u = −K, 0 is when u = 0, and R is correction. In the case where the direction is the right direction, that is, u = + K, ΔL and ΔR described in the correction amount column correspond to −K and + K, respectively.

In the correction amount determining process of the present embodiment described above with reference to FIG. 1, the welding line position gradually shifts as shown by three types of straight lines in FIG. Each of the figures shows the weld line followability when applied to each of the case where the step is shifted as shown by the three types of straight lines and the case where the step is shifted. Figure 5,
The stepwise lines shown in each of FIG. 6 indicate the weaving center position with respect to the welding line position in the case where the method of the present embodiment is applied. Further, FIGS. 11 and 12 show the followability when the conventional method is applied to the welding lines shown in FIGS. 5 and 6, and FIGS. 11 and 12 and a diagram to which the present embodiment is applied. As is apparent from comparison between FIGS. 5 and 6, according to the present embodiment, not only can the welding line be stably followed when the welding line gradually deviates, but also the welding line deviates stepwise. In this case, the followability is greatly improved.

As described above, according to the consumable electrode type arc welding method of this embodiment, the current correction amount U for the welding line of the welding torch 1 is the direction correspondence change amount u for the current correction direction and the past two times. Since it is the sum of the direction corresponding change amounts u _OLD1 and u _OLD2 for the correction direction and is variable, the tracking range is enlarged, and the trackability of the welding line is greatly improved without causing meandering beads. Even if a scanning signal is generated, it is averaged by the sum and the influence of a false scanning signal can be greatly suppressed.

In the above embodiment, the sum of the present direction correspondence change amount u and the past two direction correspondence change amounts u _OLD1 , u _OLD2 is set as the present correction amount U, but the present invention is not limited to this. However, the change amount u of the current direction and the past 3
The present modification amount U may be obtained by adding all the direction correspondence modification amounts of times or more.

[0025]

As described in detail above, according to the consumable electrode type arc welding method of the present invention, the current correction amount for the welding line of the welding torch is changed in the direction correspondence corresponding to the past predetermined times including the current correction direction. Since it is the sum of the quantities and it is variable, the tracking range is enlarged, the trackability of the welding line is greatly improved without causing meandering beads, and even if an incorrect scanning signal occurs, it is averaged by the sum. There is an effect that the influence of an erroneous scanning signal can be greatly suppressed.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining a correction amount determining procedure in a consumable electrode type arc welding method according to an embodiment of the present invention.

FIG. 2 is a flow chart for explaining a welding torch position correction procedure of the present embodiment.

FIG. 3 is a block diagram showing an arc welding apparatus to which the method of this embodiment is applied.

FIG. 4 is a table showing how the current correction amount corresponding to the previous, previous, and current correction directions in the case of applying the method of the present embodiment becomes concrete.

FIG. 5 is a graph showing the weld line followability when the method of the present embodiment is applied.

FIG. 6 is a graph showing the weld line followability when the method of the present embodiment is applied.

FIG. 7 is a schematic view showing a general V-shaped groove and a welding torch.

FIG. 8A is a schematic view showing the arrangement state of the welding torch in the V-shaped groove when the weaving center and the welding line are aligned, and FIG. 8B is the welding in the state shown in FIG. 8A. It is a graph which shows a current waveform.

9 (a) is a schematic view showing the arrangement state of the welding torch in the V-shaped groove when the weaving center is displaced to the left of the welding line, and FIG. 9 (b) shows the state shown in FIG. It is a graph which shows a welding current waveform.

10 (a) is a schematic view showing the arrangement state of the welding torch in the V-shaped groove when the weaving center is displaced to the right of the welding line, and FIG. 10 (b) shows the state shown in FIG. It is a graph which shows a welding current waveform.

FIG. 11 is a graph showing the weld line followability when the conventional method is applied.

FIG. 12 is a graph showing the weld line followability when the conventional method is applied.

[Explanation of symbols]

 1 Welding torch 2 Work 2a V-shaped groove 3 Arc welding robot 4 Robot control panel 5 Welding power supply 6 Shunt

Claims (1)

[Claims] 1. A consumable electrode type arc welding method for correcting a position of a welding torch with respect to a welding line based on a welding current detected while periodically weaving the welding torch and performing welding while following the welding line. Depending on the correction direction of the welding torch with respect to the welding line detected at a predetermined cycle based on the welding current, a positive fixed amount is a direction correspondence change amount when the correction direction is one side with respect to the welding line. If the correction direction is the other side with respect to the welding line, a negative fixed amount of the same magnitude as the positive constant correction amount is set as the direction correspondence change amount, and the weaving center of the welding torch is set. When the correction direction that coincides with the welding line is 0, 0 is set as the direction correspondence change amount, and the direction correspondence change for the past predetermined number of correction directions including this time is performed. All those obtained by adding, to the current correction amount with respect to the weld line of the welding torch, consumable electrode arc welding method characterized by moving the position of the welding torch by the current correction amount.