JP3167186B2 - Consumable electrode arc welding method - Google Patents

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 which performs welding along a welding line while weaving a welding torch right and left in a V-shaped, L-shaped or similar shape groove. The present invention relates to a welding method, and more particularly to an arc welding method using welding line automatic copying control for correctly copying a welding torch to a welding line.

[0002]

2. Description of the Related Art In automatic profiling control of a welding line, for example, a welding torch 1 is shown in a V-shaped groove as shown in FIG. 8 with the left and right (L at the left end, R at the right end, and O at the weaving center). ) Is generally used to utilize the relationship between the wire protrusion length and the welding current when weaving is performed. This type of method is disclosed in, for example,
There is a technique disclosed in, for example, JP-A-144272.

In this prior art, as shown in FIGS. 9 (a) and 9 (b), the welding current waveform when the center of the weaving coincides with the welding line is shown in FIGS. 10 (a) and 10 (b) and FIG. 11
As shown in (a) and (b), the fact that the welding current waveform is different when the weaving center does not coincide with the welding line is used.

In other words, 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. 9 (a), the
In the state shown in FIG. 10B, ΔIL = ΔIR, and FIGS. 10A and 10B
In the state shown in FIG. 11, ΔIL> ΔIR, and in the state shown in FIGS. 11A and 11B, ΔIL <ΔIR.

Therefore, if ΔIL> ΔIR, FIG.
(a) and (b), the position of the welding torch 1 is corrected rightward by a predetermined amount K, and if ΔIL <ΔIR, FIG. ,
As shown in (b), the welding torch 1
Is corrected to the left by the fixed amount K. Such a correcting operation is performed every half cycle of the weaving, and the center of the weaving of the welding torch 1 is automatically made to follow the welding line.

[0006]

However, in the conventional consumable electrode type arc welding method, since the correction amount of one welding torch position is fixed at a fixed amount K, there is a limit in the follow-up range, and the target welding range is limited. If the line changes suddenly or if the welding line deviates greatly from the center of the weaving, it cannot follow quickly. Further, if the value of the correction amount K for one time is extremely increased in order to widen the following range, there is a problem that a meandering bead is generated.

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and consumable electrode type arc welding in which the amount of correction of the welding torch position is variable to improve the followability of a welding line without generating a meandering bead. The aim is to provide a method.

[0008]

In order to achieve the above object, a consumable electrode type arc welding method according to the first invention is provided.
The welding torch is periodically welded and the position of the welding torch with respect to the welding line is corrected based on the welding current and welding is performed while following the welding line. If there is at least one correction direction different from the current correction direction with respect to the welding line of the welding torch detected in the above and the past correction direction up to a predetermined number of times before, the predetermined value is set to the predetermined value. While the torch is the current correction amount for the welding line, if the current correction direction and the previous correction direction up to a predetermined number of times are all the same direction, a value larger than the fixed value is corrected to the current correction direction. The position of the welding torch is moved in the current correction direction by the current correction amount.

A consumable electrode type arc welding method according to a second aspect of the present invention is the arc welding method similar to the first aspect, wherein the welding torch welding line detected at a predetermined cycle based on the welding current is used. Referring to the correction direction and the past correction direction up to a predetermined number of times before, when the same direction is continued up to the current correction direction, a value obtained by multiplying a preset constant value by the number of consecutive times is referred to as the welding torch. The present invention is characterized in that the position of the welding torch is moved in the current correction direction by the current correction amount with respect to the welding line.

[0010]

The consumable electrode type arc welding method according to the first aspect of the present invention described above.
In claim 1, if there is at least one difference in the correction direction up to the predetermined number of times before, the preset fixed value is used as the current correction amount as it is, while the correction direction up to the predetermined number of times before is not changed. If all are the same, a value larger than the fixed value is set as the current correction amount. In the consumable electrode arc welding method of the second invention (claim 2), when the same correction direction is continuous, By multiplying the constant value by the number of consecutive times and setting it as the correction amount this time, when the welding current is unstable and the position correction direction constantly fluctuates, the correction amount for one time can be reduced, while the weaving center and the welding line In the case where there is a large difference between the two, the amount of one correction can be increased.

[0011]

1 to 3 show a consumable electrode type arc welding method as a first embodiment of the present invention, and FIG. FIG. 2 is a flow chart for explaining the procedure for correcting the position of the welding torch, and FIG. 3 is a block diagram showing an arc welding apparatus to which the method of this embodiment is applied.

First, an arc welding apparatus to which the method of this embodiment is applied will be described with reference to FIG. 3. In FIG. 3, 1 is a welding torch, 2 is a work having a V-shaped groove 2a, and 3 is a tip of an arm. A multi-joint type arc welding robot which mounts a welding torch 1 on a part thereof and performs welding on the work 2 while controlling the position of the welding torch 1, and a robot control panel 4 for controlling the operation of the arc welding robot 3. It is.

The robot control panel 4 has a V-shaped groove 2a.
For performing a weaving operation of the welding torch 1 to the left and right within the robot, driving and controlling each arm of the arc welding robot 3 based on the calculation result, and oscillatingly driving the welding torch 1 at a predetermined weaving frequency. It is.

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

[0015] With the device configured 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 correctly copying the welding torch 1 to the welding line is performed as follows.

First, the basic procedure for correcting the welding torch position will be described with reference to FIG. 2 in a second embodiment to be described later. It is determined whether or not the welding torch 1 is in the transition section from the L end to the R end. and (step S1), and when it is in said transition section, while sampling the maximum current value IL ₁ and the minimum current value IL ₂ in the transition section (step S
2), the transition ie when the welding torch 1 is not in interval when in transition section of the L ends the R edge samples the maximum current value IR ₁ and the minimum current value IR ₂ in the transition section ( Step S3).

If it is determined that the half period of the weaving period has ended and it is not the first half period (steps S4 and S4).
5), and difference ΔIL = IL ₁ -IL _2, the maximum current value IL ₁ and the minimum current value IL ₂ in stroke to R terminal from L end,
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). Unless the stroke for at least one cycle is completed, the four current values IL ₁ , IL ₂ , IR ₁ , and IR ₂ required for the arithmetic processing from step S 6 cannot be obtained. Is being done.

After calculating these differences ΔIL and ΔIR,
A current correction direction and a current correction amount are determined by a correction amount determination process described later with reference to FIG. 1 (step S7), and a control command based on the current correction direction and the current correction amount is 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.
A description will be given of the correction amount determination processing procedure according to the present embodiment, which is first performed in step S6.
And ΔIR (step A1), and the magnitude relation is Δ
It is determined whether IL> ΔIR, ΔIL = ΔIR, or ΔIL <ΔIR.

When ΔIL> ΔIR (when it is necessary to correct rightward), the correction direction index u is set to +1.
(Step A2) If ΔIL <ΔIR (when it is necessary to correct to the left), the correction direction index u is set to −1.
(Step A3), when ΔIL = ΔIR (when the welding line position and the weaving center position match)
The correction direction index u is set to 0 (step A4), and u = ±
In the case of 1, the process proceeds to step A5 described later, while u
If = 0, the process proceeds to step A9, where the current correction amount U
Is set to 0.

In the correction amount determination processing procedure of the present embodiment, since the past N correction direction data including the current correction direction is required, it is determined whether the calculation of the correction amount determination processing has been performed N times or more in the past. Is determined (step A5). If the correction has been performed N times or more, it is determined whether or not the N correction directions up to this time are all the same (step A6). U · K is the correction amount U this time (step A7). Here, α is a predetermined value larger than 1, and K is a preset constant value.

On the other hand, when it is determined in step A5 that the calculation of the correction amount determination processing has not been performed N times or more, or in step A6, the correction direction which is different from at least one of the N correction directions up to this time. When it is determined that there is a correction value U, a value obtained by multiplying the fixed value K by the correction direction index u is set as the current correction amount U (step A8).

As described above, according to the consumable electrode type arc welding method of the first embodiment, during the N correction directions up to this time, 1
If there is a difference even at the same time, a value obtained by multiplying the fixed value K by the correction direction index u is set as the current correction amount U. On the other hand, if the values are all the same, a value α · K larger than the fixed value K is used.
Is multiplied by the correction direction index u to obtain the correction amount U this time. In the case where the welding current is unstable and the position correction direction constantly fluctuates, the correction amount for one time can be reduced. In the case where the welding line deviates greatly, the correction amount U for one time can be increased,
The followability of the welding line is greatly improved without generating a meandering bead.

Next, a description will be given of a consumable electrode type arc welding method as a second embodiment of the present invention with reference to FIGS. 4 and 5. FIG. 4 is a flowchart for explaining the welding torch position correcting procedure, and FIG. FIG. 9 is a table showing what the current correction amount corresponding to the last, last, and current correction directions is when the method of the present embodiment is applied.

Here, the apparatus to which the method of the second embodiment is applied is completely the same as that described with reference to FIG. 3, and a description thereof will be omitted. The basic procedure of correcting the position of the welding torch by the robot control panel 4 is completely the same as that described with reference to FIG. 2, and a description thereof will be omitted.

The second embodiment differs from the first embodiment in that step S in the flowchart of FIG.
7 is only the part of the correction amount determination processing procedure, and the correction amount determination processing procedure of the second embodiment will be described below with reference to FIG. First, similarly to steps A1 to A4 of the first embodiment, the first four steps B1 to B4
This time, the correction direction index u is set to +1, 0, -1 according to the correction direction.
In the case of u = ± 1, the process proceeds to step B5 described below, while in the case of u = 0, the process proceeds to step B10, and the correction amount U is set to 0 this time.

Thereafter, it is determined whether or not the current correction direction index u is equal to the previous correction direction index u _OLD1 (step B5).
_If it is determined that u = u _OLD1 (in the case of two consecutive same correction directions), it is further determined whether the current correction direction index u is the same as the correction direction index u _OLD2 two times before (step B6). .

If it is determined in step B6 that u = u _OLD2 (three times in the same correction direction), 3u
While K is used as the correction amount U this time (step B
7) If it is determined that u ≠ u _OLD2 (in the case of two consecutive same correction directions), 2u · K is used as the current correction amount U (step B8). Further, u に よ り u is obtained in step B5.
If it is determined to be _OLD1 , u · K is used as the current correction amount U (step B9).

FIG. 5 shows an example of a specific correction amount determination result by the correction amount determination processing procedure of the present embodiment described above with reference to FIG. However, in FIG. 5, L described in the column of the last two previous times, the previous time, and the current correction direction indicates that the correction direction is the left direction, that is, u = −1, 0 indicates that u = 0, and R indicates the correction direction. The direction is the right direction, that is, u = + 1, and ΔL and ΔR described in the column of the correction amount correspond to −K and + K, respectively.

Further, the correction amount determination processing procedure of the present embodiment described above with reference to FIG. 4 is based on the case where the welding line position gradually shifts as shown by three types of straight lines in FIG. Each figure shows the weld line followability when applied to each of the cases where there is a stepwise shift as shown by three types of straight lines. 6 and 7 show the weaving center position with respect to the welding line position when the method of the present embodiment is applied. FIG.
2 and 13 show the followability when the conventional method is applied to the welding lines shown in FIGS. 6 and 7, and FIGS. 12 and 13 and FIGS. As is clear from the comparison with FIG. 7, according to the present embodiment, not only can the tracking be performed stably when the welding line gradually shifts, but also particularly when the welding line shifts in a step shape. The performance is greatly improved.

As described above, according to the consumable electrode type arc welding method of the second embodiment, when the same correction direction is continuous, the constant value K is multiplied by the number of continuous times, and further multiplied by the correction direction index u. By making the correction amount U this time,
The same operation and effect as those of the first embodiment can be obtained.

In the second embodiment, in order to limit the size of the correction amount U to a maximum of 3K, the determination range of the number of consecutive correction directions is set to the past three correction directions. The present invention is not limited to this, and may be up to two times in the past, or up to four times in the past.

[0033]

As described above in detail, according to the consumable electrode type arc welding method of the present invention, if there is any difference even once in the correction direction up to a predetermined number of times, a predetermined constant value is set. While the value is used as the current correction amount as it is, if the correction directions up to a predetermined number of times before are all the same, a value larger than the fixed value is used as the current correction amount (claim 1).
In the case where the same correction direction is continuous, the constant value is multiplied by the number of continuation times and used as the current correction amount (claim 2). While the amount of one correction is reduced, the amount of one correction can be increased when the weaving center and the welding line are greatly deviated, without causing a meandering bead, This has the effect of significantly improving the followability and responsiveness of the welding line without impairing the stability.

[Brief description of the drawings]

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

FIG. 2 is a flowchart for explaining a welding torch position correcting procedure according to the embodiment.

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

FIG. 4 is a flowchart for explaining a procedure for determining a correction amount in a consumable electrode type arc welding method as a second embodiment of the present invention.

FIG. 5 is a table showing a specific example of a current correction amount corresponding to a correction direction two times before, a previous time, and a current time when the method of the second embodiment is applied.

FIG. 6 is a graph showing the weld line following ability when the method of the second embodiment is applied.

FIG. 7 is a graph showing the weld line following ability when the method of the second embodiment is applied.

FIG. 8 is a schematic view showing a general V-shaped groove and a welding torch.

FIG. 9A is a schematic view showing an arrangement state of a welding torch in a V-shaped groove when a weaving center and a welding line coincide, and FIG. 9B shows welding in the state shown in FIG. 9A. 6 is a graph showing a current waveform.

FIG. 10A is a schematic diagram showing an arrangement state of a welding torch in a V-shaped groove when a weaving center is shifted to the left side of a welding line, and FIG. 10B is a diagram showing a state shown in FIG. It is a graph which shows a welding current waveform.

FIG. 11A is a schematic diagram showing the arrangement of a welding torch in a V-shaped groove when the center of the weaving is shifted to the right from the welding line, and FIG. 11B is a diagram showing the state shown in FIG. It is a graph which shows a welding current waveform.

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

FIG. 13 is a graph showing the weld line following ability when a conventional method is applied.

[Explanation of symbols]

 Reference Signs List 1 welding torch 2 work 2a V-shaped groove 3 arc welding robot 4 robot control panel 5 welding power source 6 shunt

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-52171 (JP, A) JP-A-1-48677 (JP, A) JP-A-2-101508 (JP, A) 52592 (JP, B2) JP-B 61-17590 (JP, B2) JP-B 3-28979 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/127 B23K 9 / 12

Claims (2)

(57) [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. If there is at least one different correction direction between the current correction direction for the welding line of the welding torch detected at a predetermined cycle based on the welding current and the past correction direction up to a predetermined number of times beforehand, While the set constant value is the current correction amount for the welding line of the welding torch, if the current correction direction and the past correction directions up to a predetermined number of times are the same direction, the fixed value A consumable electrode type arc welding characterized by moving the position of the welding torch in the current correction direction by the current correction amount by a value larger than the current correction amount. Law. 2. 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. Referring to the current correction direction for the welding line of the welding torch detected at a predetermined cycle based on the welding current and the previous correction direction up to a predetermined number of times before, the same direction continues to the current correction direction. In this case, a value obtained by multiplying a preset constant value by the number of consecutive times is set as a current correction amount of the welding torch with respect to the welding line, and the position of the welding torch is moved in the current correction direction by the current correction amount. Consumable electrode type arc welding method.