JP2023064534A - Lap fillet welding method and welding device - Google Patents

Abstract

To provide a lap fillet welding method that corrects a deviation in target position of a welding wire with respect to a fillet section in lap fillet welding without weaving, and thereby inhibits generation of humping and undercut.SOLUTION: In a lap fillet welding method, a welding wire is fed to an upper plate and a lower plate that are superposed in implementing arc welding without weaving. In the lap fillet welding method, an output current to be output to a welding wire when a target position of the welding wire coincides with a corner part is stored in advance before starting repeated welding, and output current to the welding wire is detected, in order to correct a target position of the welding wire relative to the corner part according to a comparison result of the detected output current and the stored output current.SELECTED DRAWING: Figure 4

Description

The present invention relates to a lap fillet welding method and a welding apparatus.

One type of welded joint is a lap joint in which two plate materials are placed on each other substantially horizontally. The welding of the corners of the upper plate end and the lower plate of the lap joint is called lap fillet welding (for example, Patent Document 1).

Japanese Patent No. 4112213

In lap fillet welding, if the target position of the wire tip shifts toward the upper plate, the heat input to the upper plate increases, and humping beads that melt down only the upper plate are likely to occur. In addition, if it shifts to the lower plate side, the heat input to the lower plate increases, and undercuts are likely to occur.
For this reason, it is necessary to fix the upper and lower plates accurately with a jig so that the target position does not shift, and strict process control is required, such as high machining accuracy for the upper and lower plates. .
Weaving the welding torch and correcting the target position of the welding wire with an arc sensor are also used, but it is difficult to match the conditions to obtain a certain welding quality, and it is not easy to correct the target position using the arc sensor. do not have.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lap fillet welding method and a welding apparatus capable of correcting the displacement of the welding wire aiming position with respect to the fillet portion and suppressing the occurrence of humping and undercut in lap fillet welding without weaving. is to provide

A lap fillet welding method according to one aspect of the present invention is a lap fillet welding method in which a welding wire is fed to the corners of an upper plate and a lower plate that are overlapped and arc welding is performed without weaving, The output current to be output to the welding wire when the target position of the welding wire matches the corner is stored in advance before starting repeated welding, and the output current to the welding wire is detected and detected. The target position of the welding wire with respect to the corner is corrected in accordance with the result of comparison between the detected output current and the stored output current.

A welding device according to one aspect of the present invention is a welding device that feeds a welding wire to a corner of an upper plate and a lower plate that are superimposed and performs arc welding without weaving, wherein the welding wire aims at a position of a storage unit for pre-storing the output current to be output to the welding wire when the welding wire coincides with the corner before starting repeated welding; a current detection circuit for detecting the output current to the welding wire; a welding robot that moves the welding torch along the corner; and a correction circuit that corrects the target position of the welding wire with respect to the corner in accordance with a comparison result between the detected output current and the stored output current. Prepare.

According to the above, in lap fillet welding without weaving, it is possible to correct the displacement of the target position of the welding wire with respect to the fillet portion, and suppress the occurrence of humping and undercut.

It is a schematic diagram which shows the structural example of an arc welding apparatus. 1 is a block diagram showing a configuration example of a welding power source; FIG. 3 is a block diagram showing a configuration example of a correction circuit; FIG. 4 is a flowchart showing a correction processing procedure according to the embodiment; 4 is a graph showing the relationship between the amount of displacement of the target position of the welding wire and the output current.

A lap fillet welding method and a welding apparatus according to embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. Moreover, at least part of the embodiments described below may be combined arbitrarily.

Hereinafter, the present invention will be described in detail based on the drawings showing its embodiments.
FIG. 1 is a schematic diagram showing a configuration example of an arc welding apparatus, and FIG. 2 is a block diagram showing a configuration example of a welding power source 2. As shown in FIG. The arc welding apparatus according to the present embodiment is a consumable electrode gas shield arc welder for performing downward lap fillet welding. The base material A is a lap joint composed of an upper plate A1 and a lower plate A2 that are placed together substantially horizontally. The arc welding apparatus according to the present embodiment is, for example, a DC pulse welder, and performs arc welding by feeding the welding wire W to the corner formed by the end of the upper plate A1 and the lower plate A2 to perform fillet welding. implement the method.

The arc welding apparatus includes a welding robot 1 to which a welding torch 11 and a wire feed section 12 are attached, a welding power source 2, a control device 3, and a shield gas supply section (not shown). In FIG. 1, a thick line indicates a power supply cable, and a thin line indicates a control communication line.

Control device 3 sets welding conditions for welding power source 2 and controls the operation of welding power source 2 . Control device 3 also controls the operation of welding robot 1 by outputting an operation control signal to welding robot 1 . In repeated welding, an operation program for operating the welding robot 1 according to a predetermined procedure is created by teaching. The control device 3 stores the created operation program. The control device 3 controls the operation by outputting an operation control signal to the welding robot 1 according to the operation program. Further, the control device 3 includes a correction circuit 4 for correcting the target position of the welding wire W. As shown in FIG.

The welding robot 1 has a base fixed to an appropriate location on the floor. A plurality of arms are rotatably connected to the base through shafts. A welding torch 11 is held at the tip portion of the arm connected to the tip side. A servomotor is provided at the linking portion of the arm, and each arm rotates around the shaft portion by the rotational driving force of the servomotor. Rotation of the servomotor is controlled by the controller 3 . The control device 3 can move the welding torch 11 up, down, front, back, left and right with respect to the base material A by rotating each arm. An encoder for outputting a signal indicating the rotational position of the arm to the control device 3 is provided at the connecting portion of each arm. and posture recognition.

The shield gas supply unit supplies shield gas to the welding torch 11 . The shield gas is for preventing oxidation of the base material A and the welding wire W melted by the arc. The shielding gas is, for example, argon Ar, a mixed gas of carbon dioxide CO2 and helium He, or a mixed gas of argon Ar and helium He.

The welding torch 11 is made of a conductive material such as a copper alloy, and has a cylindrical contact tip that guides the welding wire W to the welded portion of the base material A and supplies the welding current Iw required to generate an arc. . The contact tip contacts the welding wire W passing therethrough and supplies the welding wire W with the welding current Iw. The welding torch 11 has a hollow cylindrical shape surrounding the contact tip, and has a nozzle for injecting the shield gas supplied from the shield gas supply part to the welded part.

The welding wire W is, for example, a solid wire, a metal cored wire or a flux cored wire and functions as a consumable electrode. The welding wire W is, for example, a pack wire that is spirally wound and stored in a pail pack, or a reel wire that is wound on a wire reel.

The wire feeder 12 has a feed roller that feeds the welding wire W to the welding torch 11 and a motor that rotates the feed roller. The wire feeding unit 12 rotates the feeding roller to draw out the welding wire W from the pail pack or wire reel, and feeds the drawn welding wire W to the welding torch 11 at a constant speed.

The welding power supply 2 includes a power supply circuit 21 , a detector 22 , a power control circuit 23 and a feed control circuit 24 . The power supply circuit 21 is connected to the contact tip of the welding torch 11 and the base material A via a power supply cable, applies a welding voltage Vw between the welding wire W and the base material A, and supplies a welding current Iw.

The detection unit 22 includes a voltage detection circuit 22a and a current detection circuit 22b. The current detection circuit 22b detects the welding current Iw flowing through the arc during the welding process, and outputs a current detection signal Id indicating the detected current value to the power supply control circuit 23. The voltage detection circuit 22 a detects the welding voltage Vw applied to the welding torch 11 and the base material A, and outputs a voltage detection signal Vd indicating the detected voltage value to the power supply control circuit 23 .

The power supply control circuit 23 outputs an error amplification signal ΔE to the power supply circuit 21 based on the current value and voltage value detected by the voltage detection circuit 22a and the current detection circuit 22b and the set voltage value and set current value. The set voltage value and the set current value are set by the controller 3, for example. The error amplification signal ΔE is, for example, a signal that indicates the difference between the detected current value and the target value of the welding current Iw. The error amplification signal ΔE may be a signal indicating the difference between the detected voltage value and the target value of the welding voltage Vw. A power supply circuit 21 receives a commercial AC power supply, performs inverter control, thyristor phase control, etc. based on the error amplification signal ΔE, and outputs a welding voltage Vw and a welding current Iw suitable for welding.

The feed control circuit 24 outputs a feed control signal for feeding the welding wire W at a feed speed corresponding to the set current value to the wire feeding section 12 to control the feed speed of the welding wire W. . Welding power supply 2 or power supply control circuit 23 also outputs a welding monitor signal indicating the welding state during the welding process to correction circuit 4 of control device 3 . The welding monitor signal is, for example, the current detection signal Id.

FIG. 3 is a block diagram showing a configuration example of the correction circuit 4. As shown in FIG. The correction circuit 4 is a computer including a processing section 40, an input section 40a, an output section 40b, and a storage section 40c.

The storage unit 40c is a non-volatile memory such as an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The storage unit 40c stores a computer program 40d for optimizing the target positions of the welding torch 11 and the welding wire W with respect to the base material A and suppressing the occurrence of humping and undercutting.

The processing unit 40 is a computer having a CPU (Central Processing Unit) or a processor such as a multi-core CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), an input/output interface, etc. The interface includes an input unit 40a , an output unit 40b and a storage unit 40c are connected. The processing unit 40 executes a process of optimizing the target position of the welding wire W with respect to the base material A by executing the computer program 40d stored in the storage unit 40c.

The input section 40 a is connected to the welding power source 2 . A welding monitor signal output from the welding power source 2, such as a current detection signal Id, is input to the input unit 40a.

The output section 40b is connected to the welding robot 1 and the welding power source 2. As shown in FIG. The processing unit 40 outputs to the welding robot 1 an operation control signal for optimizing the target positions of the welding torch 11 and the welding wire W with respect to the base material A.

FIG. 4 is a flowchart showing a correction processing procedure according to this embodiment. The control device 3 controls the operations of the welding robot 1 and the welding power source 2 to perform fillet welding of the base material A, which is a lap joint. The welding speed is 100 cm/min or more and 150 cm/min or less. A pulse period for pulse welding is, for example, 4 ms (250 Hz). Before starting repeated welding, the correction circuit 4 stores the relationship between the target position of the welding wire W and the output current value (step S11).

FIG. 5 is a graph showing the relationship between the target position of the welding wire W and the output current value. The horizontal axis indicates the target position, and the vertical axis indicates the output current. The aiming position shown in FIG. 5 indicates the amount of displacement of the aiming position from the corners of the upper plate A1 and the lower plate A2, for example, the root portion, which is set to 0. As shown in FIG. The corner to be targeted is not necessarily limited to the root, and depending on the welding conditions, a position offset from the root by a predetermined amount may be set as the target position. The output current value is the average value of the current values of the welding current Iw detected multiple times over a predetermined period. The predetermined period is at least one pulse period or longer, eg, several hundred milliseconds to one second. As shown in FIG. 4, there is a correlation between the target position and the output current value. Specifically, the displacement amount of the target position of the welding wire W and the output current value are generally proportional to each other.
In addition, FIG. 5 shows the deviation of the target position and the output current when lap welding is performed with a set current of 420 A, a set voltage of 32.0 V, a welding speed of 150 cm / min, a gap of 1 mm, and a plate thickness of 3.6 mm × 2.9 mm. It shows the relationship with

The control device 3 or the correction circuit 4 stores at least the output current value when the target position of the welding wire W coincides with the corners of the upper plate A1 and the lower plate A2 in the storage section 40c. Hereinafter, the output current value at this time will be referred to as a reference current value. In addition, the control device 3 or the correction circuit 4 stores, in the storage unit 40c, the amount of deviation of the welding wire W from another target position and the output current value when the welding wire W is at the target position. It is preferable that the control device 3 or the correction circuit 4 store a plurality of pairs of target position shift amounts and output currents. Further, the control device 3 or the correction circuit 4 may be configured to store the ratio of the amount of deviation of the target position to the amount of change in the output current.

Next, the correction circuit 4 detects the welding current Iw in the predetermined period immediately after the start of the main welding in the repeated welding by the current detection circuit 22b (step S12). Note that "immediately after the start of main welding" means after a transitional period has elapsed after the start of arc welding. Then, the correction circuit 4 calculates the output current value based on the detected welding current Iw (step S13).
Specifically, the correction circuit 4 acquires data indicating the current value of the welding current Iw from the current detection signal Id output from the welding power source 2 . Then, the correction circuit 4 calculates the moving average value of the current values for N pulse cycles as the output current value. N is an integer, and the N pulse period corresponds to, for example, 100 milliseconds or more and 1 second or less.

The correction circuit 4 determines whether or not the output current value is greater than the reference current value (step S14). If the output current value is greater than the reference current value (step S14: YES), the correction circuit 4 corrects the teaching of the welding robot 1 so that the target position of the welding wire W moves toward the lower plate A2 (step S15). That is, the correction circuit 4 operates the welding robot 1 so that the target position of the welding wire W with respect to the base material A moves toward the lower plate A2 from the target position indicated by the operation program taught in the control device 3 in advance. change the program.
Specifically, the correction circuit 4 calculates the amount of deviation of the target position based on the relationship between the output current value and the amount of deviation of the target position, and the detected and calculated output current value. The correction circuit 4 may calculate the shift amount of the target position based on the difference between the output current value and the reference current value and the ratio of the shift amount of the target position to the amount of change in the output current. The correction circuit 4 moves the target position indicated by the operation program toward the lower plate A2 by the calculated deviation amount.

When determining that the output current value is equal to or less than the reference current value (step S14: NO), the correction circuit 4 determines whether the output current value is less than the reference current value (step S16). When determining that the output current value is equal to or greater than the reference current value (step S16: NO), the correction circuit 4 finishes the correction process. If it is determined that the output current value is less than the reference current value (step S16: YES), the correction circuit 4 corrects the teaching of the welding robot 1 so that the target position of the welding wire W moves toward the upper plate A1. Call (step S17). That is, the correction circuit 4 operates the welding robot 1 so that the target position of the welding wire W with respect to the base material A moves toward the upper plate A1 from the target position indicated by the operation program taught in the control device 3 in advance. change the program.
Specifically, the correction circuit 4 calculates the shift amount of the target position based on the output current value and the relationship between the output current value and the shift amount of the target position. The correction circuit 4 may calculate the shift amount of the target position based on the difference between the output current value and the reference current value and the ratio of the shift amount of the target position to the amount of change in the output current. The correction circuit 4 moves the target position indicated by the operation program toward the upper plate A1 by the calculated deviation amount.

When the processing of step S15 or step S17 is finished, the control device 3 outputs an operation control signal to the welding robot 1 based on the operation program corrected by the above processing, thereby moving the target position of the welding wire W upward. The corners of the plate A1 and the lower plate A2 can be precisely matched.
In step S16, if it is determined that the output current value is not less than the reference current value (step S16: NO), that is, if the output current value is the reference current value, the control device 3 operates based on the pre-correction operation program. and outputs an operation control signal to the welding robot 1 .

The flow of the target position correction process has been described with reference to FIG. It is recommended to correct the operation program.
Further, when correcting the operation program, the correction circuit 4 preferably corrects the operation program while leaving the operation program before correction in the storage unit 40c, that is, without erasing the operation program before correction.

(Example)
An example will be described. Lap fillet welding with a protrusion length of 20 mm, a target angle of 45 degrees, a forward angle of 0 degrees, a set current of 420 A, a set voltage of 32.0 V, a welding speed of 150 cm / min, a gap of 1 mm, and a plate thickness of 3.69 mm × 2.9 mm. conduct. The output current value of 415 [A] when the target position is at the root portion is taken as the reference current value.
The correction circuit 4 detects the welding current Iw after a transitional period has elapsed after the start of arc welding, and when the output current value is, for example, 425 A, the robot determines that the displacement of the target position is 1 mm toward the upper plate A1. Then, the command to move the welding torch 11 during welding is corrected by -1 mm.
The correction circuit 4 detects the welding current Iw after a transitional period has elapsed after the start of arc welding. When the output current value is, for example, 405 A, the robot determines that the displacement of the target position is 1 mm toward the lower plate A2. Then, the command to move the welding torch 11 during welding is corrected by +1 mm.
As a result of the above correction processing, the welding is aimed at the root portion and a good bead is obtained.

According to the welding apparatus and the lap fillet welding method according to the present embodiment, in lap fillet welding without weaving, the deviation of the target position of the welding wire W with respect to the fillet portion is corrected, and the occurrence of humping and undercut is suppressed. can do.

Further, in the present embodiment, the target position of the welding wire W can be corrected without weaving and without using an arc sensor. Since the configuration does not use an arc sensor, there is no need to adjust various conditions using an arc sensor, and the target position can be easily corrected.

In addition, since the correction circuit 4 is configured to store in advance the relationship between the output current value and the deviation amount of the target position, and correct the target position of the welding wire W using this relationship, the target position of the welding wire W can be corrected. The position can be accurately corrected.

Furthermore, even when performing high-speed welding, for example, lap fillet welding of thin plates at a welding speed of 100 cm/min to 150 cm/min, the target position can be corrected at high speed by simple processing using the output current. , the occurrence of humping and undercut can be effectively prevented.

The welding device capable of performing the lap fillet welding method according to the present embodiment is not limited to a DC pulse welder, but may be an AC pulse welder or any other consumable electrode type welding device. can be applied. Moreover, although the automatic welding machine using the welding robot 1 has been described, the present invention may be applied to a semi-automatic welding machine.

Further, in the present embodiment, an example in which the welding current Iw is detected when the welding current Iw is stabilized and the shift amount of the target position of the welding wire W is calculated is described. The deviation amount of the target position of the welding wire W may be calculated by calculating the average value as the output current value. Although the welding current Iw immediately after the start of arc welding is not stable, there is no change in the output current value fluctuating due to the deviation of the target position. can be corrected to some extent.

Furthermore, in the present embodiment, an example of mainly correcting the shift amount of the target position has been described, but the correction circuit 4 may be configured to change other welding conditions as well.

1: Welding robot, 2: Welding power source, 3: Control device, 4: Correction circuit, 11: Welding torch, 12: Wire feeder, 21: Power supply circuit, 22: Detector, 22a: Voltage detection circuit, 22b: Current detection circuit, 23: power supply control circuit, 24: feed control circuit, 40: processing unit, 40a: input unit, 40b: output unit, 40c: storage unit, 40d: computer program, A1: upper plate, A2: lower plate, Vw: welding voltage, Iw: welding current, Vd: voltage detection signal, Id: current detection signal, ΔE: error amplification signal, W: welding wire

Claims (5)

A lap fillet welding method in which a welding wire is fed to the corners of the superimposed upper plate and lower plate and arc welding is performed without weaving,
storing in advance an output current to be output to the welding wire when the target position of the welding wire coincides with the corner before starting repeated welding;
detecting the output current to the welding wire;
A lap fillet welding method for correcting a target position of the welding wire with respect to the corner according to a comparison result between the detected output current and the stored output current. When the detected output current is larger than the stored output current, the target position of the welding wire with respect to the corner is moved toward the lower plate, and when the detected output current is smaller than the stored output current, the The lap fillet welding method according to claim 1, wherein the target position of the welding wire with respect to the corner is moved toward the upper plate. storing the relationship between the amount of displacement of the target position of the welding wire and the output current;
The lap fillet welding method according to claim 1 or 2, wherein the target position of the welding wire with respect to the corner is corrected based on the detected output current and the stored relationship. The lap fillet welding method according to any one of claims 1 to 3, wherein the welding speed is 100 cm/min or more. A welding device that feeds a welding wire to the corners of the superimposed upper plate and lower plate and performs arc welding without weaving,
a storage unit for pre-storing an output current to be output to the welding wire when the target position of the welding wire coincides with the corner before starting repeated welding;
a current detection circuit that detects an output current to the welding wire;
a welding robot that moves a welding torch along the corner;
and a correction circuit for correcting the target position of the welding wire with respect to the corner according to a comparison result between the detected output current and the stored output current.

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