JP2020049542A - Welding device and welding method - Google Patents

Abstract

To provide a welding device that can perform welding with high-precision by a simple method.SOLUTION: The welding device comprises: a welding torch that executes welding processing by weaving operation on the basis of a welding condition; a detecting part that detects welding currents during the weaving operation; and a correcting part that changes the welding condition in order to correct a heat-input quantity on the basis of change in the detected welding currents by the detecting part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a welding device.

  Generally, penetration is one of the indices for determining welding strength. In this regard, it is important to stabilize the penetration for stabilizing the welding quality. However, a gap may be formed between the members to be welded due to the accuracy of the members to be welded, and the penetration deepens in proportion to the size of the gap between the members. Therefore, depending on the presence or absence of the gap between the members and the size of the gap, the penetration varies, so that the welding quality may be deteriorated. Further, if the penetration becomes too deep, the weld metal may reach the back side of the member, and a welding defect such as “burn-through” that may cause a hole may occur.

  In this regard, Japanese Patent Application Laid-Open No. 2013-121617 discloses a method in which a backing member for suppressing burn-through is provided on the back side of the member when welding is performed.

  However, contacting the backing member when performing welding increases costs and complicates the welding operation.

  On the other hand, in Japanese Patent Application Laid-Open No. 2009-6383, as a method for preventing burn-through, a laser beam sensor is used to measure the excess height of a weld bead without providing a backing member, and the welding bead is entered based on the measurement result. A method for adjusting heat has been proposed.

JP 2013-121617 A JP 2009-6383 A

  However, measuring the extra height of the weld bead using a laser sensor requires a new sensor, which increases the cost and complicates the welding process.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a welding apparatus and a welding method capable of performing highly accurate welding by a simple method.

  The welding device of the present invention is based on a welding condition, based on welding conditions, a welding torch for performing a welding process by a weaving operation, a detection unit for detecting a welding current during the weaving operation, and a change in the welding current detected by the detection unit. And a correction unit that changes welding conditions to correct the heat input.

  The welding method of the present invention includes a step of weaving a welding torch according to welding conditions, a step of detecting a welding current during the weaving operation, and a welding condition for correcting a heat input amount based on a change in the detected welding current. .

  As described above, according to the welding apparatus and the welding method of the present invention, highly accurate welding can be performed by a simple method.

FIG. 2 is a diagram illustrating a welding device 1 according to the first embodiment. FIG. 4 is a diagram illustrating a weaving operation of the welding torch 30 according to the first embodiment. It is a figure explaining a specific example of welding. It is a flowchart explaining the correction process which changes the welding conditions of the welding device 1 based on Embodiment 1. FIG. 4 is a flowchart illustrating a current difference detection process based on the first embodiment. FIG. 4 is a diagram illustrating a change in welding current of welding device 1 based on the first embodiment. FIG. 4 is a diagram illustrating a welding condition correction process of a welding control unit 14 based on the first embodiment. It is a figure explaining the example of welding by welding device 1 based on Embodiment 1. It is a figure explaining the weaving operation of welding torch 30 based on Embodiment 2. It is a figure explaining change of welding current of welding device 1 based on Embodiment 2. It is a figure explaining welding condition correction processing of welding control part 14 based on Embodiment 3. FIG. 14 is a diagram illustrating an arc sensor function of welding device 1 according to a fourth embodiment.

  Embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

(Embodiment 1)
<Overall configuration of welding equipment>
FIG. 1 is a diagram illustrating a welding device 1 according to the first embodiment.

  With reference to FIG. 1, a welding device 1 according to the first embodiment includes a welding robot 20 installed on a floor or the like in a factory, a welding power supply device 13, a welding control device 10, a wire feeding device 40, , A welding current measuring device 50. Here, the welding robot 20 is an arc welding robot for performing welding using heat generated by arc discharge generated between the welding wire W and the member 100. The welding robot 20 operates the connecting arm 21 connected via a plurality of joints each rotating in a predetermined direction, the welding torch 30 attached to the distal end of the connecting arm 21, and the connecting arm 21. This is an articulated robot including an actuator 22 that moves the welding torch 30. The wire feeding device 40 is configured to feed out the welding wire W at a predetermined speed and supply the welding wire W to the tip of the welding torch 30 when arc welding is performed.

  The welding control device 10 is provided for controlling the operation of the welding robot 20 and the welding power supply device 13.

  The welding control device 10 has a plurality of functional blocks. Specifically, the welding control device 10 includes a welding power source control unit 11, a welding control unit 14, a storage unit 60, a robot operation control unit 15, and an A / D conversion unit 12.

  The storage unit 60 stores various programs and data. In the present example, the storage unit 60 includes a welding condition storage unit 62 and a correction amount storage unit 64.

  The welding control unit 14 performs a welding operation based on a program stored in the storage unit 60. The welding control unit 14 outputs various instructions to each unit to execute a welding operation based on the welding condition data stored in the welding condition storage unit 62. The welding control unit 14 corrects welding conditions based on the correction amount data stored in the correction amount storage unit 64.

  The welding power supply control unit 11 outputs a command signal for controlling heat input to the welding power supply device 13 in accordance with an instruction from the welding control unit 14.

  The welding power supply device 13 is configured to perform a predetermined operation based on a control command from the welding control device 10.

  The welding power supply device 13 has a function of controlling the supply speed of the welding wire W fed from the wire feeding device 40, and uses the power supply cables CB (+) and CB (-) to connect between the welding torch 30 and the member 100. It has a function of supplying a predetermined amount of power (heat input). Specifically, a power supply cable CB (+) for welding voltage application is connected to welding robot 20, and a power supply cable CB (−) is connected to member 200. The welding power supply device 13 outputs electric power adjusted to a current value and a voltage value corresponding to the command signal from the welding power supply control unit 11 to the welding robot 20, and causes an arc discharge between the welding wire W and the member 100. Is configured to generate.

  The welding current measuring device 50 is provided on the power supply cable CB (-) side, and measures a welding current during a welding operation. The welding current measuring device 50 feeds back the measurement result to the welding control device 10. The A / D converter 12 converts an analog signal from the welding current measuring device 50 into a digital signal and outputs the digital signal to the welding controller 14.

  The welding power supply control unit 11 outputs a command signal for adjusting the supply speed of the welding wire W fed from the wire feeding device 40 to the welding power supply device 13 according to an instruction from the welding control unit 14. The wire feeding device 40 adjusts the supply speed of the welding wire W according to a command signal from the welding power supply device 13.

  The arc sensor control unit 16 instructs the robot operation control unit 15 to execute a predetermined operation by the arc sensor function.

  The robot operation control unit 15 controls the actuator 22 according to an instruction from the welding control unit 14. The robot operation control unit 15 outputs an operation command for operating the connection arm 21 and the welding torch 30 for controlling the position of the welding torch 30 with respect to the actuator 22. The actuator 22 operates the connecting arm 21 and the welding torch 30 based on the operation command transmitted from the welding control device 10 to operate the welding torch 30 at a predetermined position. Specifically, the welding control device 10 causes the welding torch 30 to perform a weaving operation during the welding process.

  The welding control unit 14, the welding torch 30, the welding current measuring device 50, and the actuator 22 are examples of the “correction unit”, the “welding torch”, the “detection unit”, and the “drive unit” of the present invention.

<Weaving operation>
FIG. 2 is a diagram illustrating a weaving operation of welding torch 30 based on the first embodiment.

  FIG. 2A shows a case where a welding torch 30 is arranged between the members 100A and 100B to perform welding between the members. The weaving operation of the welding torch 30 refers to an operation of swinging left and right while traveling in the traveling direction. The traveling direction is a direction in which the welding line L extends.

  In this example, when the members 100A and 100B are viewed from the side, a state in which the welding torch 30 swings right and left during the weaving operation is illustrated. In the present example, the tip movement of the welding torch 30 viewed from the direction in which the welding line L extends is depicted.

  In FIG. 2B, the trajectory of the welding torch 30 when the members 100A and 100B are viewed from above is indicated by a dotted line.

  In this example, a trajectory in which the welding torch 30 moves in a sinusoidal shape in a top view while traveling in the traveling direction from the center of the groove of the members 100A and 100B is shown. The weaving operation is a periodic operation, and a period from swinging right and left from the center of the groove to returning to the center of the groove again is defined as one cycle. The welding line L is located at the center of the sinusoidal amplitude.

<Specific examples of welding>
FIG. 3 is a diagram illustrating a specific example of welding. FIG. 3 shows a welding connection between the member 100A and the member 100B. 3A, 3B, and 3C show welded joints in which the distance between the member 100A and the member 100B is different due to variations in the dimensions of the members.

  As shown in FIG. 3A, the case where welding is performed in a state where there is no gap between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, the case where the penetration is shallow is shown because there is no gap between the members.

  As shown in FIG. 3B, the case where welding is performed in a situation where a gap is formed between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, there is shown a case where the penetration is deep because there is a gap between the members. Therefore, there is a possibility that the phenomenon that the penetration is not constant and is not stable as compared with a situation where there is no gap between the members.

  As shown in FIG. 3 (C), a case where welding is performed in a situation where a large gap is formed between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, the case where the gap between the members is large and the burn-through of the weld metal occurs has been shown. Therefore, when the gap between the members is large, there is a possibility that a burn-through phenomenon occurs. FIG. 3 illustrates that in conventional welding, the penetration quality varies depending on the variation in the interval between the joining members and the presence or absence of a gap, and the joining quality may not be stable.

  The welding apparatus 1 according to the first embodiment estimates the degree of penetration based on the change in the waveform of the welding current, and changes the welding conditions to correct the heat input. Specifically, if it is estimated that the penetration is deep or a sign of burn-through, the welding conditions are changed to reduce the heat input.

  FIG. 4 is a flowchart illustrating a correction process for changing the welding conditions of welding apparatus 1 based on the first embodiment.

  Referring to FIG. 4, welding device 1 starts welding (step S0). Specifically, the welding control unit 14 instructs the welding power source control unit 11 and the robot operation control unit 15 to execute a welding process according to the welding condition data stored in the welding condition storage unit 62. The welding power supply control unit 11 outputs a command signal for setting the supply speed of the welding wire W and the welding voltage in the welding process to the welding power supply device 13 in accordance with an instruction from the welding control unit 14. The welding power supply device 13 outputs a command current that regulates the supply speed of the welding wire W to the wire feeding device 40 according to a command signal from the welding power supply control unit 11. In addition, welding power supply device 13 applies the set welding voltage to power supply cable CB (+). The robot operation control unit 15 outputs a command signal for setting an operation of the welding robot 20 in the welding process to the actuator 22 according to an instruction from the welding control unit 14. The actuator 22 operates the connecting arm 21 according to a command signal from the robot operation control unit 15, and performs the weaving operation described with reference to FIG.

  Next, the welding device 1 measures a welding current (step S2). Specifically, the welding current measuring device 50 outputs the measured welding current to the A / D converter 12. The A / D converter 12 converts the analog signal of the welding current from the welding current measuring device 50 into a digital signal and outputs the digital signal to the welding controller 14. The welding control unit 14 stores the value of the welding current from the A / D conversion unit 12 in the storage unit 60.

  Next, the welding device 1 determines whether or not one cycle of the weaving operation has ended (step S4). Specifically, the welding control unit 14 determines whether one cycle of the weaving operation by the actuator 22 has been completed.

  Next, when the welding device 1 determines that one cycle of the weaving operation has not ended, the process returns to step S2 and repeats the above processing.

  On the other hand, when it is determined in step S4 that one cycle of the weaving operation has ended (YES in step S4), welding device 1 executes a current difference detection process (step S6). Specifically, the welding control unit 14 performs a current difference detection process for detecting a difference between the maximum value and the minimum value of the welding current during one period of the weaving operation.

FIG. 5 is a flowchart illustrating a current difference detection process based on the first embodiment.
Referring to FIG. 5, welding apparatus 1 acquires current data n points in one cycle of weaving (step S20). Specifically, the welding control unit 14 obtains n points of current data of one cycle of weaving stored in the storage unit 60.

  Next, the welding device 1 sorts the current data n points in descending order (step S22). Specifically, the welding control unit 14 rearranges the data array of n points in descending order for the calculation process.

  Next, the welding device 1 calculates the maximum value (max) of the current (step S24). Specifically, the welding control unit 14 calculates, as the maximum value (max), the average value of the data of the upper 5% of the data at the n points rearranged in descending order.

  Next, the welding device 1 calculates the minimum value (min) of the current (step S26). Specifically, the welding control unit 14 calculates the average value of the data of the lower 5% of the data of the n points rearranged in descending order as the minimum value (min).

  Next, the welding device 1 calculates a current difference (step S28). The welding control unit 14 calculates a difference between the calculated maximum value and the initial value as a current difference.

  Then, the process ends (return). Specifically, the welding device 1 proceeds to step S8 in FIG. In this example, the method of calculating the maximum value or the minimum value using the average value of 5% of the data of the upper or lower data of the entire data of the n points has been described, but the present invention is not limited to this. The maximum value (max) or the minimum value (min) of the point data array may be used as it is.

  Referring to FIG. 4 again, welding apparatus 1 executes a correction amount calculation process (step S8). Specifically, the welding control unit 14 calculates a correction amount based on the correction amount data stored in the correction amount storage unit 64 based on the detection result of the current difference detection processing. The calculation of the correction amount will be described later.

  Next, the welding apparatus 1 determines whether a correction process for changing the welding conditions is necessary (Step S10). Specifically, the welding control unit 14 determines whether the calculated correction amount is smaller than 0. If the welding control unit 14 determines that the calculated correction amount is smaller than 0, it estimates that the penetration is deep or that it is a sign of burn-through. Then, the welding control unit 14 determines that correction processing for changing welding conditions is necessary to reduce the heat input.

  Next, in Step S10, when it is determined that the correction process is necessary (YES in Step S10), the welding device 1 executes a welding condition correction process (Step S12). Specifically, the welding control unit 14 changes the welding conditions and instructs the welding power source control unit 11 to execute the welding process based on the changed welding conditions.

  On the other hand, if it is determined in step S10 that the correction process is not necessary (NO in step S10), the welding device 1 skips step S12 and proceeds to step S14.

Next, the welding device 1 determines whether or not the welding process has been completed (step S14).
If it is determined in step S14 that the welding is not completed (NO in step S14), the welding device 1 returns to step S2 and repeats the above processing.

  On the other hand, if it is determined in step S14 that welding has been completed (YES in step S14), the welding device 1 ends the process (END).

FIG. 6 is a diagram illustrating a change in welding current of welding device 1 based on the first embodiment.
FIG. 6A shows a case where welding is performed in a state where there is no gap between the members 100A and 100B. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. Also, a case where the welding torch 30 moves to the positions of the center and the edge of the groove between the members is shown.

FIG. 6B shows a change in the welding current in the case of FIG. 6A.
The welding current increases as the protrusion distance, which is the distance from the welding torch 30 to the member, decreases, and as the protrusion distance increases, the welding current decreases. Therefore, during one cycle of weaving, the projecting distance between the welding torch 30 and the end region becomes shorter as the welding torch 30 approaches the edge region of the groove between the members, and the welding torch 30 becomes closer to the center as the welding torch 30 approaches the center. The protruding distance from the central area becomes longer. Therefore, as shown in FIG. 6B, the welding current has a waveform in which the welding current decreases in the center region and increases in the end region.

  FIG. 6C shows a case where welding is performed in a state where there is a gap between the members 100A and 100B. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. Also, a case where the welding torch 30 moves to the positions of the center and the edge of the groove between the members is shown.

FIG. 6D shows a change in the welding current in the case of FIG. 6C.
As described above, the welding current increases as the protrusion distance, which is the distance from the welding torch 30 to the member, decreases, and as the protrusion distance increases, the welding current decreases.

  Therefore, during one cycle of weaving, the projecting distance between the welding torch 30 and the end region decreases as the welding torch 30 approaches the end region of the groove between the members, and the welding torch 30 approaches the center as the welding torch 30 approaches the center. The distance from the central area becomes longer. Therefore, as shown in FIG. 6 (D), the welding current decreases in the central region and increases in the end region. Further, as shown in the present example, when there is a gap between the members, the molten metal surface in the central region is further lowered, so that the distance is further increased, and the value of the welding current is further reduced in the central region. Therefore, the current difference (amplitude) between the maximum current and the minimum current when welding is performed without a gap, and the current difference (amplitude) between the maximum current and the minimum current when welding is performed with a gap. Is different. Specifically, the current difference (amplitude) between the maximum current and the minimum current when welding with a gap is larger than the current difference between the maximum current and the minimum current when welding without a gap. It becomes larger than the difference (amplitude). It is possible to estimate the degree of penetration based on the change in the waveform of the welding current.

  The welding apparatus 1 sets the amplitude of the waveform of the welding current having no gap between the members as the reference value. If a change in the amplitude of the waveform of the welding current is detected beyond the reference value, it can be determined that the penetration is deep or that it is a precursor to burn-through.

  FIG. 7 is a diagram illustrating a welding condition correction process of the welding control unit 14 based on the first embodiment.

  Referring to FIG. 7, a correction table of the welding conditions stored in correction amount storage unit 64 of storage unit 60 is shown. As an example, it is a correction table of a command current output from the welding power supply device 13 to the wire feeding device 40 as welding conditions. Specifically, the correction amount is calculated based on the current difference calculated using the linear function correction table. As an example, the correction amount is calculated using a linear function (correction amount = a × current difference + b).

  The welding control unit 14 corrects a command current (command reference current) serving as a reference to be output to the wire feeding device 40 as welding conditions. Specifically, when the calculated current difference is large, the welding control unit 14 increases the correction amount of the command current and sets the calculated current difference to be small when the calculated current difference is large, using the current difference in a situation where there is no gap as a reference value. The smaller the correction amount of the command current, the smaller the amount.

  FIG. 8 is a diagram illustrating a specific example of welding by the welding device 1 according to the first embodiment.

  As shown in FIG. 8A, a case where welding is performed in a state where there is no gap between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, there is shown a case where the penetration is deep because there is no gap between the members.

  As shown in FIG. 8B, the case where welding is performed in a state where a gap is formed between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, it is assumed that there is a gap between the members, so that the penetration is deep, and the welding conditions are changed to reduce the heat input. In the present example, when the amplitude change of the waveform of the welding current is different from the amplitude change (predetermined amplitude change) when there is no gap between the members, the heat input amount is reduced according to the difference in the amplitude change. In this example, when the amplitude of the welding current is greater than the amplitude when there is no gap between the members, the heat input is reduced.

  Specifically, the command current output to the wire feeding device 40 is corrected to reduce the speed at which the welding wire W is fed. Thereby, since the welding current is reduced, the heat input can be reduced. Therefore, even if there is a gap between the members, it is possible to reduce the amount of heat input, make the penetration constant, and stabilize.

  As shown in FIG. 8C, the case where welding is performed in a situation where a large gap is formed between the members 100A and 100B is shown. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. In this example, it is assumed that the gap between the members is large and the penetration is considerably deep, and the welding conditions are changed to further reduce the heat input.

  Specifically, the command current output to the wire feeding device 40 is corrected to reduce the speed at which the welding wire W is fed. Thereby, since the welding current is reduced, the heat input can be reduced. Therefore, even in a situation where there is a gap between the members, it is possible to reduce the amount of heat input and to prevent the penetration from deepening, and to suppress the burn-through of the weld metal.

  The welding apparatus 1 according to the first embodiment estimates the degree of penetration based on a change in the waveform of the detected welding current, and changes the welding conditions for correcting the heat input. The heat input is corrected by changing the feeding speed of the welding wire W as a welding condition to reduce the welding current. Thereby, highly accurate welding is possible by a simple method.

(Embodiment 2)
FIG. 9 is a diagram illustrating a weaving operation of welding torch 30 based on the second embodiment.

  Referring to FIG. 9, the weaving operation of welding torch 30 according to the second embodiment swings right and left and up and down while traveling in the traveling direction from the center of the groove between the members. The welding robot 20 performs a weaving operation in a first direction (left-right direction) perpendicular to the traveling direction of the welding torch 30 and a second direction (vertical direction) perpendicular to the traveling direction and the first direction (left-right direction). . This makes it possible to suppress the interference between the end region of the member and the welding torch 30 during the weaving operation.

  FIG. 10 is a diagram illustrating a change in welding current of welding device 1 based on the second embodiment.

  FIG. 10A shows a case where welding is performed in a state where there is no gap between the members 100A and 100B. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. Also, a case where the welding torch 30 moves to the positions of the center and the edge of the groove between the members is shown.

FIG. 10B shows a change in the welding current in the case of FIG.
The welding current increases as the protrusion distance, which is the distance from the welding torch 30 to the member, decreases, and as the protrusion distance increases, the welding current decreases.

  In the weaving operation according to the second embodiment, in addition to the left-right swing, a vertical swing is added as compared with the weaving operation according to the first embodiment. As the welding torch 30 approaches the edge region of the groove, the protrusion distance between the welding torch 30 and the end region increases, and as the welding torch 30 approaches the center, the projection distance between the welding torch 30 and the central region decreases. Therefore, as shown in FIG. 10 (B), the welding current increases in the central region, the current waveform decreases in the end region, and the current waveform has a large current difference. Therefore, the current difference can be easily detected by the weaving operation according to the second embodiment.

  FIG. 10C shows a case where welding is performed in a state where there is a gap between the members 100A and 100B. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. Also, a case where the welding torch 30 moves to the positions of the center and the end of the groove is shown.

FIG. 10D shows a change in the welding current in the case of FIG. 10C.
As described above, the welding current increases as the protrusion distance, which is the distance from the welding torch 30 to the member, decreases, and as the protrusion distance increases, the welding current decreases. Therefore, during one cycle of weaving, the protruding distance between the welding torch 30 and the end region becomes longer as the welding torch 30 approaches the end region of the groove, and the welding torch 30 and the central region become closer as the welding torch 30 approaches the center. Distance becomes shorter. Therefore, as shown in FIG. 10 (D), the welding current decreases in the central region, and increases in the end region. Furthermore, when there is a gap between the members, the molten metal surface in the central region is further lowered, so that the distance is further increased, and the welding current is further reduced in the central region.

  Therefore, the current difference (amplitude) between the maximum current and the minimum current when welding is performed without a gap, and the current difference (amplitude) between the maximum current and the minimum current when welding is performed with a gap. Is different. Specifically, the current difference (amplitude) between the maximum current and the minimum current when welding with a gap is larger than the current difference between the maximum current and the minimum current when welding without a gap. It becomes smaller than the difference (amplitude). It is possible to estimate the degree of penetration based on the change in the waveform of the welding current.

  The welding apparatus 1 sets the amplitude of the waveform of the welding current having no gap between the members as the reference value. If a change in the amplitude of the waveform of the welding current is detected beyond the reference value, it can be determined that the penetration is deep or that it is a precursor to burn-through. In the present example, when the amplitude change of the waveform of the welding current is different from the amplitude change (predetermined amplitude change) when there is no gap between the members, the heat input amount is reduced according to the difference in the amplitude change. In this example, when the amplitude of the welding current is smaller than the amplitude when there is no gap between the members, the heat input is reduced.

  When it is estimated that the penetration is deep or a sign of burn-through, the welding device 1 executes a welding condition correction process for correcting the welding conditions. Since the welding condition correction process has the same concept as that described in the first embodiment, detailed description thereof will not be repeated.

  When it is estimated that the penetration is deep or a sign of burn-through, the welding control unit 14 corrects a command current (command reference current) serving as a reference to be output to the wire feeding device 40 as welding conditions. The command current output to the wire feeding device 40 is corrected to reduce the speed at which the welding wire W is fed. Thereby, since the welding current is reduced, the heat input can be reduced. Therefore, even in a situation where there is a gap between the members, it is possible to reduce the amount of heat input and to prevent the penetration from deepening, and to suppress the burn-through of the weld metal.

  The welding apparatus 1 according to the second embodiment estimates the degree of penetration based on a change in the waveform of the welding current detected in the same manner as described in the first embodiment, and changes the welding conditions for correcting the heat input. Thereby, highly accurate welding is possible by a simple method.

(Embodiment 3)
In the first and second embodiments, the correction for reducing the welding current as a change in the welding condition to correct the heat input has been described. Specifically, the method of correcting the heat input by changing the speed at which the welding wire W is fed has been described. However, the welding current is not limited to the speed at which the welding wire W is fed, and the welding current is not limited to the speed at which the welding torch 30 is fed. It also depends on the protrusion distance, which is the distance between the members. As described above, the welding current increases as the protrusion distance decreases, and the welding current decreases as the protrusion distance decreases. Therefore, the welding control unit 14 may instruct the robot operation control unit 15 to change the protrusion distance set as the reference value of the welding condition between the welding torch 30 and the member. Specifically, by setting the protrusion distance to be longer than the reference value, the distance between the welding torch 30 and the member becomes longer, so that the welding current can be reduced.

  The heat input is represented by the following equation.

  As shown in the above equation, the heat input depends not only on the welding current but also on the welding voltage E and the feed speed v of the welding torch 30. The feed speed v is a speed in the traveling direction of the welding torch 30. The heat input can be changed by adjusting the voltage value of the welding voltage E. Specifically, it is possible to reduce the heat input by correcting the welding voltage E to a low value. The welding control unit 14 may instruct the welding power source control unit 11 to set so as to lower the value of the welding voltage E applied to the welding torch 30. Alternatively, the welding control unit 14 can change the heat input amount by adjusting the feed speed v of the welding torch 30. The welding condition is at least one of the welding current, the welding voltage E, and the feed speed v of the welding torch 30.

  FIG. 11 is a diagram illustrating a welding condition correction process of the welding control unit 14 based on the third embodiment.

  Referring to FIG. 11, a correction table of the welding conditions stored in correction amount storage unit 64 of storage unit 60 is shown. As an example, it is a correction table of a feed speed of the welding torch 30 as a welding condition. Specifically, the correction amount is calculated based on the difference between the current difference calculated using the linear function correction table and the reference value. As an example, the correction amount is calculated using a linear function (correction amount = a # × current difference + c).

  The welding controller 14 changes the feed speed v of the welding torch 30 by instructing the robot operation controller 15 as welding conditions. Specifically, the welding control unit 14 sets the correction amount to be small when the calculated current difference is small and sets the correction amount to be small when the calculated current difference is large, using the current difference in a situation where there is no gap as a reference value. Increase the correction amount. The welding control unit 14 can reduce the heat input by increasing the feed speed v of the welding torch 30 by the correction amount. Therefore, even if there is a gap between the members, the amount of heat input is reduced to prevent the penetration from deepening and to suppress the burn-through of the weld metal.

  The welding apparatus 1 according to the third embodiment estimates the degree of penetration based on the detected change in the waveform of the welding current, and as a welding condition for correcting the heat input, the protrusion distance, the welding voltage E, or the feed speed of the welding torch 30. To change. Thereby, highly accurate welding is possible by a simple method.

(Embodiment 4)
In the fourth embodiment, a method using an arc sensor function for changing the heat input amount will be described.

  FIG. 12 is a diagram illustrating an arc sensor function of welding device 1 according to the fourth embodiment.

  FIG. 12A shows a case where welding is performed in a state where there is no gap between the members 100A and 100B. As an example, a case is shown in which a welding wire W is fed from a welding torch 30 and a weld metal flows into and welds between members 100A and 100B by arc discharge. Also, a case where the welding torch 30 moves to the positions of the center and the edge of the groove between the members is shown. In this example, a case where the weaving operation according to the second embodiment is performed will be described.

FIG. 12B shows a change in the welding current in the case of FIG.
As described with reference to FIG. 10B, the welding current increases in the central region, the current waveform decreases in the end region, and the current waveform has a large current difference. Here, the target current of the arc sensor is set to the average value of the welding current.

  The arc sensor function is a function of adjusting the protrusion distance of the welding torch 30 so that the average welding current becomes the target current of the arc sensor. Even when the protrusion distance changes due to the variation of the members, it is possible to execute a stable welding operation following the changed distance.

  FIG. 12C illustrates a case where welding is performed in a state where there is a gap between the members 100A and 100B.

FIG. 12D shows a change in the welding current in the case of FIG. 12C.
As described with reference to FIG. 10 (D), when there is a gap between members, the molten metal surface in the central region is further lowered, so that the distance is further increased, and the welding current is further reduced in the central region. As a result, the average welding current decreases. Therefore, the operation of adjusting the average current of the welding current to be the target current of the arc sensor is performed by the arc sensor function.

FIG. 12E shows a state where the arc sensor function is executed.
FIG. 12F shows a change in the welding current in the case of FIG.

  The case where the protrusion distance of the welding torch 30 is changed by the arc sensor function in order to adjust the average current of the welding current to be the target current of the arc sensor is shown. Specifically, the case where the protruding distance is reduced is shown. By adjusting the protrusion distance, the average current of the welding current is adjusted to the target current of the arc sensor.

  The welding apparatus 1 according to the fourth embodiment estimates the degree of penetration based on the detected change in the waveform of the welding current, and changes the welding conditions to correct the heat input. Specifically, when it is estimated that the penetration is deep or a sign of burn-through, the welding conditions are changed to reduce the heat input.

  Specifically, the welding control unit 14 instructs the arc sensor control unit 16 to change the target current of the arc sensor. The welding control unit 14 sets the value of the target current of the arc sensor low in order to reduce the heat input. The robot operation control unit 15 changes the protrusion distance of the welding torch 30 by an arc sensor function according to an instruction from the arc sensor control unit 16. Specifically, the amount of heat input is reduced by changing the protrusion distance of the welding torch 30 to be longer. Therefore, even in a situation where there is a gap between the members, it is possible to reduce the amount of heat input to prevent the penetration from deepening and to suppress the burn-through of the weld metal.

  The welding apparatus 1 according to the fourth embodiment estimates the degree of penetration based on a change in the waveform of the detected welding current, and changes the target current of the arc sensor as welding conditions for correcting the heat input. Thereby, highly accurate welding is possible by a simple method.

[Effects]
Next, the operation and effect of the embodiment will be described.

  As shown in FIG. 1, the welding apparatus 1 of the embodiment includes a welding torch 30 that performs a welding process by a weaving operation by a welding robot 20 based on welding conditions, and a welding current that detects a welding current during the weaving operation. A measuring device 50 and a welding control device 10 are provided. The welding control device 10 includes a welding control unit 14 that changes welding conditions in order to correct a heat input amount based on a change in welding current detected by the welding current measuring device 50. The welding conditions can be changed based on the change in the waveform of the welding current detected by the welding current measuring device 50 to correct the heat input, so that highly accurate welding can be performed with a simple method.

  The welding control unit 14 may change the welding conditions in order to correct the heat input based on the change in the amplitude of the waveform of the welding current detected by the welding current measuring device 50. Since the heat input can be corrected by changing the welding conditions based on the change in the amplitude of the waveform of the welding current, highly accurate welding can be performed by a simple method.

  The welding control unit 14 changes the welding conditions based on the difference in the amplitude change of the waveform of the welding current detected by the welding current measuring device 50 in order to reduce the heat input. When the amplitude of the waveform of the welding current is reduced, the welding conditions are changed to reduce the heat input, so that it is possible to suppress the penetration to be too deep or the burn-through to occur.

  The welding apparatus 1 is further provided with a correction amount storage unit 64 that stores a correction table for calculating the correction amount of the welding condition. The welding control unit 14 calculates a correction amount for correcting the heat input amount based on the amplitude change amount of the welding current waveform detected by the welding current measuring device 50 and the correction table. By using the correction table, it is possible to change the welding conditions in a simple manner.

  The welding control unit 14 may change a welding current or a welding voltage applied to the welding torch 30 as welding conditions. The amount of heat input can be corrected by changing the welding current or welding voltage as welding conditions, and highly accurate welding can be performed by a simple method.

  The welding control unit 14 may change the feeding speed of the welding wire W sent to the welding torch 30 in order to change the welding current. Since the welding current can be easily changed by changing the feeding speed of the welding wire W, the welding conditions can be changed in a simple manner.

  The welding control unit 14 may instruct the welding power supply control unit 11 to change the amount of the command current that defines the feed speed of the welding wire W. The welding power supply controller 11 controls a command current output from the welding power supply device 13 to the wire feeding device 40. The wire feeding device 40 adjusts the feeding speed of the welding wire W according to a command current from the welding power supply device 13. The welding conditions can be changed in a simple manner by changing the amount of the command current.

  The welding control unit 14 instructs the arc sensor control unit 16 to change the target current of the arc sensor for correcting the position of the welding torch 30 with respect to the groove of the member based on the welding current detected by the welding current measuring device 50. You may. The arc sensor control unit 16 changes the protrusion distance of the welding torch 30 by the arc sensor function with respect to the robot operation control unit 15. This makes it possible to correct the amount of heat input, and it is possible to perform highly accurate welding by a simple method.

  The welding control unit 14 may instruct the robot operation control unit 15 to change the speed of the welding torch 30 in the traveling direction of the weaving operation. The amount of heat input can be corrected by changing the feed speed of the weaving operation of the welding torch 30, and highly accurate welding can be performed by a simple method.

  The welding control unit 14 further includes an actuator 22 that performs a weaving operation in a left-right direction perpendicular to the traveling direction of the welding torch 30 and in a vertical direction perpendicular to the traveling direction and the left-right direction. Since the welding torch 30 performs the weaving operation in the horizontal direction and the vertical direction, the change in the waveform of the welding current increases. Since welding conditions are changed to correct the heat input based on the change, highly accurate welding is possible.

  The welding method of the welding apparatus 1 includes a step of weaving the welding torch 30 in accordance with welding conditions, a step of detecting a welding current during the weaving operation, and a step of correcting a heat input amount based on a change in the detected welding current. Changing the welding conditions. Since the heat input can be corrected by changing the welding conditions based on the detected change in the waveform of the welding current, highly accurate welding can be performed with a simple method.

(Other embodiments)
In the above embodiment, the method of performing arc welding using the welding robot 20 which is an articulated robot has been described. However, the welding robot 20 may have a drive mechanism capable of weaving the welding torch 30. However, the invention is not limited to the articulated robot. The welding robot 20 may be an orthogonal robot including a three-axis manipulator.

  Further, in the above-described embodiment, the method of changing various values as the welding condition in order to correct the heat input amount has been described, but a plurality of values may be changed.

  The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  REFERENCE SIGNS LIST 1 welding device, 10 welding control device, 11 welding power supply control unit, 12 A / D conversion unit, 13 welding power supply device, 14 welding control unit, 15 robot operation control unit, 16 arc sensor control unit, 20 welding robot, 21 connection Arm, 22 actuator, 30 welding torch, 40 wire feeder, 50 welding current measuring device, 60 storage unit, 62 welding condition storage unit, 64 correction amount storage unit, L welding line.

Claims (11)

A welding torch for performing a welding process by a weaving operation based on welding conditions;
A detection unit that detects a welding current during the weaving operation,
A correction unit configured to change the welding condition in order to correct the heat input based on a change in the welding current detected by the detection unit.   The welding device according to claim 1, wherein the correction unit changes the welding condition in order to correct a heat input amount based on a change in amplitude of a welding current waveform detected by the detection unit.   The welding device according to claim 2, wherein the correction unit changes the welding condition to reduce the heat input amount based on a difference in amplitude change of a welding current waveform detected by the detection unit. A memory having a correction table for calculating a correction amount of the welding condition,
The welding device according to claim 2, wherein the correction unit calculates a correction amount for correcting the heat input amount based on the amplitude change amount of the welding current waveform detected by the detection unit and the correction table.   The welding device according to claim 1, wherein the correction unit changes the welding current or a welding voltage applied to the welding torch as the welding condition.   The welding device according to claim 5, wherein the correction unit changes a feeding speed of a wire fed to the welding torch to change the welding current.   The welding device according to claim 6, wherein the correction unit changes a current amount of a command current that defines a feed speed of the wire.   The welding device according to claim 1, wherein the correction unit changes a target current of an arc sensor that corrects a position of the welding torch with respect to a groove of a welding target based on a welding current detected by the detection unit.   The welding device according to claim 1, wherein the correction unit changes a speed of the welding torch in a traveling direction of the weaving operation.   The welding device according to claim 1, further comprising a driving unit that performs a weaving operation in a first direction orthogonal to a traveling direction of the welding torch and a second direction orthogonal to the traveling direction and the first direction. Weaving a welding torch according to welding conditions;
Detecting a welding current during the weaving operation;
Changing the welding conditions to correct the heat input based on the detected change in the welding current.