JP3167187B2 - 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. 7 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. 8 (a) and 8 (b), the welding current waveform when the weaving center coincides with the welding line is shown in FIGS. 9 (a) and 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 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. 8 (a), the
Using the fact that ΔIL = ΔIR in the state shown in FIG. 9B, ΔIL> ΔIR in the states shown in FIGS. 9A and 9B, and ΔIL <ΔIR in the states shown in FIGS. 10A and 10B. I have.

Accordingly, 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, then 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]

To achieve the above object, a consumable electrode type arc welding method according to the present invention provides a method for welding a welding torch based on a welding current detected while periodically weaving the welding torch. The welding direction is corrected according to a correction direction to the welding line of the welding torch detected at a predetermined cycle based on the welding current. If it is one side with respect to the welding line, a positive fixed amount is set as the direction corresponding change amount, and if the correction direction is the other side with respect to the welding line, it has the same magnitude as the positive constant correction amount. A fixed amount of negative is set as the direction-corresponding change amount. If the correction direction in which the weaving center of the welding torch coincides with the welding line is 0, 0 is set as the direction-corresponding change amount. Then, the sum of the direction-corresponding change amounts for the correction directions of the past predetermined times including the current time is defined as the current correction amount of the welding torch with respect to the welding line, 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 as the sum of the direction correspondence change amounts for the past predetermined correction directions including the current time. In addition, the following range becomes large, and even if an erroneous tracing signal is generated, the averaging is performed by sum and the influence of the erroneous tracing 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. 2 is a flowchart for explaining the procedure for correcting the position of the welding torch, FIG. 3 is a block diagram showing an arc welding apparatus to which the method of the present embodiment is applied, and FIG. Table showing how the current correction amount corresponding to the previous and current correction directions will be specifically, and FIGS. 5 and 6 are graphs showing welding line followability when the method of the present embodiment is applied. is there.

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, reference numeral 1 denotes a welding torch, 2 denotes a work having a V-shaped groove 2a, and 3 denotes 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 supply for supplying electric power for arc welding, and reference numeral 6 denotes a shunt attached to the welding power supply 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.

[0014] 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 of correcting the position of the welding torch will be described with reference to FIG. 2. It is determined whether or not the welding torch 1 is in a transition section from the L end to the R end (step S1). If it is in the interval, while sampling the maximum current value IL ₁ and the minimum current value IL ₂ in the transition section (step S2), and if not in the transition section that is the welding torch 1 to the L terminal of R ends If it is in the transition period, samples the maximum current value IR ₁ and the minimum current value IR ₂ in the transition section (step S3).

When it is determined that the half cycle of the weaving cycle is completed and not the first half cycle (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.

If ΔIL> ΔIR, the correction direction is the right direction (R end direction) with respect to the welding line, and a predetermined positive fixed amount + K (mm) is set as the direction-dependent change amount u. When the setting is made (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 corresponding change amount u (step A3). If <IR, 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 corresponding change amount u (step A4).

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

FIG. 4 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. 4, L described in the column of the last-last, previous, and current correction directions indicates that the correction direction is the left direction, that is, u = −K, 0 indicates that u = 0, and R indicates the correction direction. The direction is the right direction, that is, u = + K, and ΔL and ΔR described in the column of the correction amount correspond to −K and + K, respectively.

The correction amount determination processing of the present embodiment described above with reference to FIG. 1 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 the displacement is stepwise as shown by the three types of straight lines. FIG.
The stepped lines shown in each of FIG. 6 show the weaving center position with respect to the welding line position in the case where the method of this embodiment is applied. 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 FIGS. As is apparent from comparison with FIGS. 5 and 6, according to the present embodiment, not only can the welding line stably follow when the welding line gradually shifts, but particularly, the welding line shifts in a step shape. The case tracking ability is greatly improved.

As described above, according to the consumable electrode type arc welding method of the present embodiment, the current correction amount U for the welding line of the welding torch 1 is the direction corresponding change amount u for the current correction direction and the past two correction amounts. Since the direction change amount u _OLD1 and u _OLD2 for the correction direction is variable and becomes the sum, the follow-up range becomes large, and the followability of the welding line is greatly improved without generating a meandering bead. Even if a copying signal is generated, it is averaged by the sum and the influence of an incorrect copying signal can be greatly suppressed.

In the above embodiment, the sum of the current direction change amount u and the past two direction change amounts u _OLD1 and u _OLD2 is the current correction amount U, but the present invention is not limited to this. It is not what is done, but the current
The current correction amount U may be obtained by adding all of the direction-corresponding change amounts of times or more.

[0025]

As described above in detail, 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 correspondence with the correction direction in the past predetermined times including the current time. Since the sum is variable and the sum is variable, the tracing range is large, the followability of the welding line is greatly improved without generating a meandering bead, and even if an erroneous tracing signal is generated, the tracing is averaged by the sum. There is an effect that the influence of an incorrect copying signal can be greatly suppressed.

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

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

FIG. 6 is a graph showing the weld line following ability 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 an arrangement state of a welding torch in a V-shaped groove when a weaving center and a welding line coincide, and FIG. 8B shows welding in a state shown in FIG. 6 is a graph showing a current waveform.

FIG. 9A is a schematic view showing an arrangement state of a welding torch in a V-shaped groove when a weaving center is shifted to the left side from a welding line, and FIG. 9B is a view showing a state shown in FIG. It is a graph which shows a welding current waveform.

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

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

FIG. 12 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 (1)

(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. According to a correction direction of the welding torch with respect to the welding line detected at a predetermined cycle based on the welding current, if the correction direction is one side with respect to the welding line, a positive fixed amount is a direction corresponding change amount When the correction direction is the other side with respect to the welding line, a fixed amount of negative having the same magnitude as the positive constant correction amount is set as a direction corresponding change amount, and the welding torch weaving center and If the correction direction corresponding to the welding line is 0, 0 is set as the direction corresponding change amount, and the direction corresponding change for the past predetermined number of correction directions including this time is set. 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.