JP2008260050A - Arc welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm a misalignment of a welding torch tip at a low cost without applying a load to a worker when teaching a confirmation program or installing a confirmation facility for the misalignment confirmation of the tip of a welding torch. Provided is an arc welding apparatus that can reliably detect the occurrence of a position shift.
A robot controller 7 moves a welding wire 4 at the tip of a welding torch 2 into a circular space of a metal plate 5 and then moves the welding torch 2 to an X axis of an orthogonal coordinate system defined in advance on the metal plate 5. When the contact between the welding wire 4 at the tip of the welding torch 2 and the metal plate 5 is detected by the detection device 6 in each direction, the movement of the welding torch 2 is stopped and the welding torch is moved. 2 The position of the tip is stored, and the presence / absence of positional deviation of the robot 1 is confirmed from the plurality of welding torch 2 stored in the movement in each direction.
[Selection] Figure 1

Description

  The present invention relates to an arc welding apparatus using a robot, and more particularly to an arc welding apparatus having a function of confirming a tip position of a welding torch attached to a robot.

The arc welding robot has an arc welding torch at its tip, and performs welding work by moving the welding torch. The robot is controlled by a servo motor provided on each axis, and the position of each axis motor is feedback controlled by a robot controller.
However, the tip position of the welding torch for performing the actual arc welding operation is only estimated by calculation in the robot controller based on the position of each axis motor. Therefore, the robot controller cannot recognize the displacement of the welding torch even if the displacement of the welding torch from the tip position of the welding torch occurs due to an error in attaching the welding torch to the robot or deformation due to interference between the welding torch and the surroundings. . As a result, there is a possibility that a welding failure may be made by performing a welding operation while leaving the misalignment.
In order to solve this problem, Patent Document 1 automatically confirms whether or not the welding torch tip is misaligned by a confirmation program for bringing the welding wire at the tip of the welding torch into contact with the reference bar. In Patent Document 2, instead of making the welding torch tip contact, a photoelectric switch is used to automatically perform the welding operation after confirming that the welding torch tip is not misaligned by a confirmation program.
On the other hand, in Patent Document 3, as a method for detecting the wire tip position of a welding torch, a measurement opening having an opening symmetrical to two orthogonal axes and a measurement table having an end surface for measuring the vertical displacement of the welding torch are provided. A positional deviation amount measuring device using a provided measuring plate is disclosed. This measurement plate is installed so that the center of the measurement opening is located at the horizontal reference point in the horizontal direction of the welding robot, and the upper end surface of the measurement table is located at the height of the vertical reference point in the vertical direction of the robot. ing.
Patent Document 4 discloses a technique in which a welding wire at the tip of a welding torch is brought into contact with a contact plate having a conical recess instead of the measurement plate of Patent Document 6.
JP 2000-288733 A Japanese Utility Model Publication 2-133267 JP 2000-167668 A JP 2003-39354 A

Among the conventional inventions related to the confirmation of the welding torch tip position, Patent Literature 1 and Patent Literature 2 can automatically confirm whether or not the welding torch tip is displaced. However, when the operator performs in advance the teaching of the confirmation program for moving the welding torch tip to the position of the reference bar or photoelectric switch, an accuracy of 1 [mm] or less is required, and the operator's high ability is required. There are challenges. Even when the photoelectric switch is applied, teaching at a position crossing the light emitting portion of the photoelectric switch is indispensable, and there is no difference in placing a burden on the operator who performs the teaching to some extent.
Furthermore, when the position shift of the welding torch tip is detected by the apparatus of Patent Document 1, a means for prohibiting the operator from changing the teaching position of the confirmation program so that the welding torch tip and the reference bar come into contact with each other. There is also a problem that it is not taken. In other words, there is a risk that the operator may change the teaching point of the confirmation program without taking measures against the displacement of the welding torch so that the apparent displacement of the welding torch does not occur. This problem can also occur in Patent Document 2 to which a photoelectric switch is applied.
Further, in Patent Document 3, it is necessary to install so that the center of the measurement opening of the misalignment measurement plate is located at the horizontal reference point in the horizontal direction of the robot, and this installation requires a lot of labor. Also, the position on the coordinates calculated by the robot and the physical position of the tip of the welding torch need to be completely coincident with each other, and it is very troublesome to set the physical position of the initial welding torch. is there. Furthermore, it is necessary to provide a measurement table for detecting the vertical position shift separately from the measurement opening for detecting the horizontal position shift, which is expensive.
In Patent Document 4, in order to obtain a cost for providing a conical recess in the contact plate and to obtain a correction amount in the height direction, the length of the welding wire at the tip of the welding torch is the last time each time a confirmation operation is performed. There is a problem that adjustments must be made to be the same as at the time of confirmation.

  The present invention has been made in view of such problems, and it is inexpensive to check the position deviation of the welding torch tip without applying a load to the operator when teaching the confirmation program or installing the confirmation equipment. It is an object of the present invention to provide an arc welding apparatus that can confirm misalignment and can reliably detect misalignment of the tip of the welding torch.

In order to solve the above problem, the present invention is configured as follows.
The arc welding apparatus according to claim 1, a robot having a plurality of joints, a robot controller that controls the robot, and a welding wire that is attached to a tip of a hand of the robot and is supplied from a wire supply device protrudes from the tip. In an arc welding apparatus comprising a welding torch and a welding power source connected to the robot controller to supply welding power to a welding wire at the tip of the welding torch, and performing welding using the welding wire at the tip of the welding torch as a consumable electrode,
The arc welding apparatus detects a contact between a metal plate having a circular hole fixed at an arbitrary position within the movable range of the robot, a welding wire at the tip of the welding torch, and the metal plate, and sends it to the robot controller. The robot controller moves the welding wire at the tip of the welding torch into the circular hole and then moves the welding torch to the X axis of the orthogonal coordinate system defined in advance on the metal plate. When the contact between the welding wire at the tip of the welding torch and the metal plate is detected by the detection device in the movement in each direction, the welding torch is stopped and the welding is stopped. The tip position of the torch is stored, and the misalignment detection of the welding torch from the plurality of tip positions of the welding torch stored in the movement in the respective directions. A current position acquisition process for performing a calibration process for setting a reference position for the operation and storing the welding torch tip position by operating the welding torch in the same manner as the calibration process with the calibration process completed And detecting whether or not the welding torch is misaligned from the reference position and the position obtained by the current position acquisition process.

  The arc welding apparatus according to claim 2, wherein in the calibration process and the current position acquisition process, the welding torch is moved in each of positive and negative directions of an X-axis and a Y-axis of an orthogonal coordinate system defined for the metal plate. First, the welding torch is moved in the positive direction of the X axis of the orthogonal coordinate system until it contacts the inner edge of the space portion of the metal plate, and the contact between the welding wire at the tip of the welding torch and the metal plate is detected. Then, the movement of the welding torch is stopped and the tip position of the welding torch is stored as the first position, and then the X-axis in the orthogonal coordinate system in the negative direction until the inner edge of the space portion of the metal plate is contacted. When the welding torch is moved and contact between the welding wire at the tip of the welding torch and the metal plate is detected, the movement of the welding torch is stopped and the tip position of the welding torch is set to the second position. And storing the orthogonal coordinates until the midpoint between the first position and the second position is obtained and the welding torch is moved to the midpoint until it contacts the inner edge of the space portion of the metal plate from the midpoint. When the welding torch is moved in the positive direction of the Y-axis of the system and contact between the welding wire at the tip of the welding torch and the metal plate is detected, the movement of the welding torch is stopped and the tip position of the welding torch is set to the third position. And then moving the welding torch in the negative direction of the Y-axis of the orthogonal coordinate system until it contacts the inner edge of the space portion of the metal plate, and the contact between the welding wire at the tip of the welding torch and the metal plate Is detected, the movement of the welding torch is stopped, the tip position of the welding torch is stored as a fourth position, and a fifth position which is a midpoint between the third position and the fourth position is obtained. .

  The arc welding apparatus according to claim 3, wherein the robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance, and the operation program changes the attitude of the welding torch to the metal plate. The welding torch is moved in the positive and negative directions of the X and Y axes of the orthogonal coordinate system defined on the metal plate in a state parallel to the Z axis of the orthogonal coordinate system defined by When contact with the metal plate is detected during the movement, the movement of the welding torch is stopped and the tip position of the welding torch is stored.

  5. The arc welding apparatus according to claim 4, wherein the robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance, and the operation program changes the attitude of the welding torch to the metal plate. The welding torch is moved in the positive and negative directions of the X and Y axes of the orthogonal coordinate system defined on the metal plate in a state tilted with respect to the Z axis of the orthogonal coordinate system defined by When contact with the metal plate is detected during the movement, the movement of the welding torch is stopped and the tip position of the welding torch is stored.

  6. The arc welding apparatus according to claim 5, wherein the robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance, and the operation program changes the attitude of the welding torch to the metal plate. The welding torch is moved in the positive and negative directions of the X and Y axes of the orthogonal coordinate system defined on the metal plate in a state parallel to the Z axis of the orthogonal coordinate system defined by When the contact with the metal plate is detected during the movement, the movement of the welding torch is stopped and the tip position of the welding torch is memorized, and then the attitude of the welding torch is defined as Z in the orthogonal coordinate system defined on the metal plate. The welding torch is moved in the positive and negative directions of the X-axis and Y-axis of the Cartesian coordinate system defined on the metal plate in a state inclined with respect to the axis, It stops the movement of the welding torch and for detecting the contact between the metal plate in the movement and to store the position of the tip of the welding torch.

  The arc welding apparatus according to claim 6, wherein the robot controller includes a storage unit that stores the fifth position obtained in the calibration process as the reference position, and the reference position stored in the storage unit. And the presence or absence of misalignment is detected based on the difference from the fifth position obtained in the current position acquisition process, and if the difference is larger than a preset allowable value, information on the occurrence of misalignment is output to the outside. It is characterized by doing.

  The arc welding apparatus according to claim 7, wherein the robot controller displays a message of occurrence of misalignment by a teaching device connected to the robot controller when the difference is larger than a preset allowable value. Features.

  The arc welding apparatus according to an eighth aspect is characterized in that the robot controller outputs a signal to a warning light connected to the robot controller when the difference is larger than a preset allowable value.

  The arc welding apparatus according to claim 9, wherein the robot controller authenticates an operator when storing the fifth position in the storage unit, and stores the fifth position only when the authentication is completed. It memorize | stores in a part.

  The arc welding apparatus according to claim 10 is characterized in that the robot controller executes the current position acquisition process according to the operation program during continuous operation of the robot, and detects the presence or absence of a position shift.

According to the first and second aspects of the present invention, the metal plate having a circular space is simply fixed within the operation range of the robot as the installation of the misalignment confirmation equipment without using a special sensor. The processing is easy and inexpensive, and there is no need for accurate positioning during installation.
Further, since the presence / absence of misalignment is detected without using the teaching position of the operation program, even if the operator changes the teaching point position of the operation program, there is a possibility that the apparent misalignment of the welding torch will not occur. However, it is possible to reliably detect the occurrence of the displacement of the welding torch.
According to the third aspect of the present invention, when teaching the reference position setting operation program, the welding wire at the tip of the welding torch may be positioned in a circular space provided in the metal plate, and thereafter Since the operation of detecting the edge of the circular hole and the confirmation of the amount of positional deviation are also automatically performed, it is not necessary for the operator to accurately teach the position of the tip of the welding torch in advance.
According to the fourth and fifth aspects of the present invention, in the case where a positional deviation in the height direction occurs in addition to the horizontal positional deviation while keeping the cost without using the positional deviation confirmation equipment other than the metal plate. Can be reliably detected.
According to the sixth to eighth aspects of the present invention, when a positional deviation occurs, it can be reliably notified to the operator.
Further, according to the invention described in claim 9, since the continuous operation is interrupted for the positional deviation confirmation, and the operator can automatically confirm whether or not the positional deviation has occurred without performing the confirmation operation. The burden on the user can be reduced and the operation rate of the robot can be maintained.
According to the tenth aspect of the present invention, since only the authorized operator can change the reference position for confirming the positional deviation, it is possible to prevent the reference position from being easily changed and the positional deviation of the welding torch. Can be reliably detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall view of a robot system according to the present invention. In FIG. 1, reference numeral 1 denotes a robot having a plurality of joint axes, and a welding torch 2 is attached to the tip.
The robot 1 includes a welding wire feeding device 11 on the arm, and the welding wire feeding device 11 sends the welding wire 4 stored in the welding wire can 10 to the welding torch 2. The fed welding wire 4 passes through the welding torch 2 and comes out from the tip of the welding torch 2.
A high voltage current is supplied to the welding wire 4 by the welding power source 9 during arc welding, but when the tip position of the welding torch is confirmed in the present invention, a low voltage (for example, about 24 V) is applied to the welding wire 4. Like that.
A robot controller 7 controls the robot 1 and the welding power source 9. FIG. 2 shows a block diagram in the robot controller 7. A command is output from the servo command unit 707 to a servo motor (not shown) of each joint axis of the robot 1, and a signal from a position detector provided in each servo motor is received by a feedback receiving unit 708.
The robot controller 7 is usually connected with a teaching device 8 for an operator to operate the robot 1. The operation device is provided with a display screen for displaying various information such as a numeric keypad and other keys for operation and input of the robot, an emergency stop switch, and the current position and internal state of the robot 1.
The operator moves the tip position of the welding torch attached to the tip of the robot 1 to a desired position by pressing an operation key of each axis of the robot (servo motor of each joint axis) arranged on the teaching device 8. Similarly, the position fed back from the robot 1 is stored in the robot controller 7 by pressing a memory key arranged on the teaching device 8.
By repeating the operation of moving the robot 1 to a desired position by the teaching device 8 and storing the position, the robot controller 7 can store a series of operations of the robot 1 as an operation program.
In the operation program, in addition to the operation of the robot 1, it is designated to input / output signals to / from an external device such as the teaching device 8 connected to the robot controller 7, or an input signal from the outside is used to operate the robot 1. It is also possible to specify a start / stop condition or to output a signal to an external device under a predetermined condition.
In FIG. 1, various keys on the teaching device 8 are omitted.

Reference numeral 5 denotes a metal plate 5 for confirming misalignment, and is fixed at an arbitrary position within the reachable range of the welding torch 2 at the tip of the robot 1. In this embodiment, the metal plate 5 has a plate thickness of about 2 [mm], and has a diameter of 30 [mm] which is about 2 [mm] larger than the diameter of the cylindrical nozzle portion 3 of the welding torch 2 as shown in FIG. A circular hole is formed and is connected to the ground wire shown in FIG. Thus, since the metal plate 5 is small, even if it is always installed around the robot 1, it does not become an obstacle to the welding operation. The metal plate 5 may be attached to a columnar body in the vicinity of the robot 1 as an L-shaped plate as shown in FIG. As shown in FIGS. 3 and 4, the metal plate 5 has a very simple shape, can be easily processed, and can be manufactured at low cost.
The detection device 6 monitors the voltage difference between the welding wire 4 and the ground wire connected to the metal plate 5.
When the welding wire 4 contacts the metal plate 5, the voltage between the welding wire 4 and the ground wire of the metal plate 5 drops to 0 [V], so that the detection device 6 makes the welding wire 4 contact the metal plate 5. Can be detected. When detecting the contact, the detection device 6 outputs a contact signal to the robot controller 7. The robot controller 7 can capture the feedback position from the servo motor of each joint axis of the robot 1 in accordance with the timing at which the contact detection signal input unit 712 receives the contact signal. From the feedback position of each joint axis and the shape data of each axis arm and welding torch of the robot, the position of the welding torch tip viewed from the robot reference coordinate system is obtained by calculation. The shape data of each axis arm and welding torch of the robot is preset in the parameter storage unit 706 and the tool dimension storage unit 702.

Next, a calibration procedure for setting the reference position of the welding torch tip position will be described. FIG. 5 is a top view of the metal plate 5, which serves as a reference when the positional deviation is confirmed. A coordinate system in which the horizontal plane of the metal plate 5 is the XY plane is set in advance as shown in FIG. Hereinafter, this coordinate system is referred to as a user coordinate system.
The operator operates the teaching device 8 to call and execute a reference position setting operation program taught in advance. The robot controller 7 operates the robot 1 in accordance with the reference position setting operation program to move the tip of the welding torch 2 upward near the center of the hole of the metal plate 5 taught, and then lowers the welding torch 2 as shown in FIG. Thus, the welding wire 4 at the tip of the welding torch 2 is positioned in the hole of the metal plate 5.

The subsequent operation of the welding torch 2 based on the reference position setting operation program will be described with reference to FIG. First, the tip of the welding torch 2 is moved at a low speed in the plus direction of the X axis of the user coordinate system from the state shown in FIG. When it is detected by the signal from the detection device 6 that the welding wire 4 at the tip of the welding torch 2 is in contact with the metal plate 5, the welding calculated based on the feedback position of each joint axis servo motor of the robot at that moment. The position P0 of the tip of the torch is stored and the operation of the robot 1 is stopped.
Next, the tip of the welding torch 2 is similarly moved at a low speed in the negative direction of the X axis of the user coordinate system, and the contact from the welding wire 4 and the metal plate 5 at the tip of the welding torch 2 is detected by a signal from the detection device 6. Then, as in the case of P0, the position P1 of the welding torch tip at that moment is calculated and stored, and the operation of the robot 1 is stopped.

When the storage of P0 and P1 is completed, the robot controller 7 obtains the midpoint P2 of P0 and P1 by the calculation unit 703 by calculating P2 = (P0 + P1) / 2, and moves the tip of the welding torch 2 to P2. When the tip of the welding torch 2 reaches P2, the tip of the welding torch 2 is moved at a low speed in the Y-axis plus direction of the user coordinate system from P2, and when it is detected that the welding wire 4 and the metal plate 5 are in contact with each other, The instantaneous position P3 of the welding torch is stored and the operation of the robot 1 is stopped.
Next, the tip of the welding torch 2 is similarly moved at a low speed in the Y-axis negative direction of the user coordinate system, and it is detected by the signal from the detection device 6 that the welding wire 4 and the metal plate 5 at the tip of the welding torch 2 are in contact with each other. Then, the position P4 of the welding torch tip at that moment is stored and the operation of the robot 1 is stopped.
Next, the robot controller 7 obtains the midpoint P5 of P3 and P4 by the calculation unit 703 by calculating P5 = (P3 + P4) / 2.
When P5 is obtained, the robot controller 7 displays a message such as “Do you want to store the calculated position as a reference position? (Y / N)” on the display screen of the teaching device 8, and prompts the operator to answer. If the operator replies “YES”, the robot controller 7 stores P5 in the reference position storage unit 701 of the robot controller 7 using the reference position as a reference position. As shown in FIG. 5, when the welding torch 2 is perpendicular to the XY plane of the user coordinate system, P5 is positioned at the center of the circular hole of the metal plate 5.

As described above, the diameter of the circular hole of the metal plate 5 is slightly larger than the diameter of the cylindrical nozzle portion 3 of the welding torch 2. Therefore, the amount of movement of the robot 1 when performing the contact operation between the welding wire 4 and the edge of the hole is small, and the time required for checking the displacement can be shortened.
Further, in the reference position setting operation program of this embodiment, when the tip of the welding torch is positioned in the hole of the metal plate 5 as shown in FIG. 5, it is only necessary that the welding wire 4 passes through the hole. When teaching this operation program, it is not necessary to position the tip of the welding torch strictly at the center of the hole. Therefore, the operator is not forced to perform highly accurate work when teaching the reference position setting operation program.
Further, the reference position is not held as the teaching position of the operation program, and the reference position is obtained by calculation based on the position where the welding wire 4 and the metal plate 5 are in contact with each other. Even if the teaching point is changed, there is no adverse effect on the confirmation of the displacement.
In the actual contact operation, the feedback position in a state where the welding wire 4 and the metal plate 5 are in contact with each other and the welding wire 4 is elastically deformed may be taken in. To avoid such a situation, the position of the tip of the welding torch is not memorized when contact is detected and the robot is stopped, and the welding wire 4 and the metal plate 5 are separated when the robot is operated in the opposite direction. May be detected by the detection device 6 and the tip position of the welding torch may be calculated from the instantaneous feedback position and stored.

The calibration procedure for setting the reference position has been described above. However, when the reference position is set, the current position of the tip of the welding torch 2 can be checked to determine whether there is a displacement. Similarly, an operation program for setting the reference position is executed.
After the robot 1 moves the welding torch 2 near the center of the taught hole, the robot 1 moves in the positive direction of the X axis of the user coordinate system of the metal plate 5 and touches the metal plate 5 according to the operation program. The position P00 of the welding torch tip is recorded and stopped. Next, the position P10 of the tip of the welding torch at the moment of contact with the metal plate 5 is recorded by operating in the minus direction of the X axis. Next, after moving the tip of the welding torch 2 to the position of the middle point P20 (P20 = (P00 + P10) / 2) calculated by the calculation unit 703, and further from the position of P20 in the Y axis plus direction. The position P30 of the tip of the welding torch at the moment of contact with the metal plate 5 is recorded and stopped. Next, it moves in the negative direction of the Y-axis, records the position P40 of the tip of the welding torch at the moment when it contacts the metal plate 5, and stops. The robot controller 7 determines the midpoint P50 of P30 and P40 by the calculation of P50 = (P30 + P40) / 2.

Here, as in the case of the reference position setting on the display screen of the teaching device 8, the robot controller 7 displays a message “Do you want to store the calculated position as the reference position? (Y / N)” on the display screen of the teaching device 8. Is displayed and the operator's response is encouraged. When confirming the positional deviation, answer “NO”. Then, the robot controller 7 displays a message such as “Do you want to check the displacement? (Y / N)” on the display screen of the teaching device 8, and if the operator answers “YES”, the robot controller 7 The difference between P5 stored in the storage unit 701 and P50 obtained this time is calculated. If “NO” is answered here, the process is terminated without confirming the displacement.
In the present embodiment, if the welding torch 2 is actually moved to P5 and P50, even if a positional deviation occurs, the apparent position will coincide. However, when a positional deviation has occurred, the values of P5 and P50 obtained by calculation will be different.
Since the metal plate 5 is fixed at a predetermined position, the difference ΔP (ΔP = P50−P5) between the reference positions P5 and P50 stored in the reference position storage unit 701 is the amount of positional deviation of the tip of the welding torch 2. It becomes.
If the absolute value of the difference ΔP is larger than the preset allowable displacement, the robot controller 7 displays a message to that effect on the display screen of the teaching device 8 assuming that the displacement of the tip position of the welding torch 2 has occurred. Inform the worker. A buzzer sound may be used instead of the message on the display screen. Further, it may be output to a display device (not shown) such as an external controller connected to the robot controller 7 or a warning light.

  In addition, during the continuous operation of the robot 1, the operation program for setting the reference position is executed by the operator's operation or automatically during the interval in which the robot can perform other operations such as setup change. It is also possible. In such a case, it is also possible to confirm the positional deviation without obtaining an answer from the operator as described above. In this case, if the difference ΔP is larger than the positional deviation allowable value, if the welding operation is performed as it is, there is a possibility that a defective product is produced. Therefore, in addition to outputting the fact on the display screen of the teaching device 8 or the like, the robot 1 Stop continuous operation.

In the first embodiment, it is possible to automatically confirm the displacement in the horizontal direction, but it is not possible to confirm whether or not the displacement has occurred in the height direction. Will be. Therefore, in this embodiment, an operation program that can detect a positional deviation in the height direction is used.
FIG. 7 is a side view showing the positional deviation checking operation in the present embodiment.
In the first embodiment, the welding torch 2 is moved in the X axis direction and the Y axis direction of the user coordinate system in a posture orthogonal to the XY plane of the user coordinate system set on the metal plate 5 as shown in FIG. In the embodiment, as shown in FIG. 7, the welding torch moves in the X-axis direction and the Y-axis direction while being tilted with respect to the Z-axis of the user coordinate system. FIG. 7A shows a state in which the reference position is set, and FIG. 7B shows a state in which a positional deviation in the height direction has occurred. 7A and 7B, it can be seen that a difference ΔP is generated between the horizontal midpoints P5 and P50 due to the positional deviation in the height direction.
That is, even if no positional deviation has occurred in the horizontal direction, if a positional deviation has occurred in the height direction, a difference ΔP is generated between P5 and P50, and this is executed by executing the same reference position setting operation program. Misalignment can be detected.
By using an operation program that operates in such a manner that the welding torch 2 is inclined with respect to the metal plate 5 in this way, it is possible to detect not only the horizontal displacement but also the height displacement by a single confirmation operation. become able to.
In the present embodiment, unlike the first embodiment, when the welding torch 2 is actually moved to P5 and P50, when a positional deviation occurs, the apparent position also differs between the two. Also, the values of P5 and P50 obtained by the calculation will be different if a positional deviation has occurred.

  When it is desired to clarify whether the misalignment is due to the horizontal misalignment of the welding torch 2 or the misalignment in the height direction, the welding torch is orthogonal to the metal plate 5 as in the first embodiment. In this state, a misalignment confirmation operation is performed to confirm that there is no misalignment in the horizontal direction. After that, the welding torch 2 is tilted as shown in FIG. If a position shift is detected at this point, a position shift has occurred in the height direction.

As described above, when a message such as “Do you want to store the calculated position as the reference position? (Y / N)” is displayed on the display screen of the teaching device 8 after the confirmation operation by the reference position setting operation program. When the operator answers “YES”, the reference position obtained at that time is stored.
Here, if “YES” is replied due to an operator's operation mistake or the like, the reference position (P5) previously stored in the reference position storage unit 701 in the case of the first and second embodiments is overwritten with P50. I can't prevent that. If the reference position is easily changed, it will not be possible to detect the actual position deviation.
Therefore, in the present embodiment, data of the reference position (P5) obtained in the first and second embodiments is not easily changed by the operator. Specifically, whether or not the operator has the authority to change the contents of the reference position storage unit 701 so that the reference position (P5) once stored in the reference position storage unit 701 is not easily overwritten on P50. Authenticate by number or password.

That is, when a message such as “Do you want to store the calculated position as a reference position? (Y / N)” is displayed on the display screen of the teaching device 8 and the operator answers “YES”, the robot controller 7 A message such as “Rewrite the reference position. Enter the PIN number” is displayed on the display screen of the teaching device 8. A message such as “Please enter your password.” May be displayed instead of the password.
If the operator knows the password or password in advance, that is, has the authority to rewrite the reference position, the correct password or password can be entered using the numeric keypad of the teaching device 8 or the software keyboard displayed on the display screen. The P50 calculated this time can be stored in the reference position storage unit 701 of the robot controller 7 as a new reference position.
By preventing the unauthorized operator from rewriting the reference position, it is possible to reliably detect the occurrence of a positional deviation.
In addition to the password and password, the teaching device 8 may be provided with a fingerprint authentication device to check whether the operator has the authority to rewrite the reference position with the fingerprint of the worker.

The whole block diagram of the arc welding apparatus of the present invention. FIG. 3 is a control block diagram of the robot controller 7. The oblique view of the metal plate used with the arc welding apparatus of this invention. The oblique view of another example of the metal plate used with the arc welding apparatus of this invention. The oblique view which shows the mode of position shift confirmation operation | movement of the arc welding apparatus of this invention. The top view which shows the contact point of the metal plate and welding torch front-end | tip used by this invention. The side view which shows the mode of position shift confirmation operation | movement in 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot 2 Welding torch 3 Nozzle 4 Welding wire 5 Metal plate 6 Detection apparatus 7 Robot controller 8 Teaching apparatus 9 Welding power supply 10 Welding wire can 11 Welding wire feeding apparatus 700 CPU
701 Reference position storage unit 702 Tool dimension storage unit 703 Calculation unit 704 Welding condition storage unit 705 Operation program storage unit 706 Parameter storage unit 707 Servo command unit 708 Feedback receiving unit 709 Teaching device input / output unit 710 Welding condition output unit 711 Arc welding input Output unit 712 Touch detection signal input unit P0, P00 Touch detection position P1, P10 Touch detection position P2, P20 Touch calculation position P3, P30 Touch detection position P4, P40 Touch detection position P5, P50 Touch calculation position

Claims (10)

A robot having a plurality of joints, a robot controller that controls the robot, a welding torch that is attached to the tip of a hand of the robot and that is supplied from a wire supply device and protrudes from the tip, and is connected to the robot control device In an arc welding apparatus comprising a welding power source for supplying welding power to a welding wire at the tip of the welding torch, and performing welding using the welding wire at the tip of the welding torch as a consumable electrode,
The arc welding apparatus is a metal plate having a circular hole fixed at an arbitrary position in the movable range of the robot;
A detection device that detects contact between the welding wire at the tip of the welding torch and the metal plate and transmits it to the robot controller;
The robot controller moves the welding wire at the tip of the welding torch into the circular hole, and then moves the welding torch in the positive and negative directions of the X-axis and Y-axis of the orthogonal coordinate system defined in advance on the metal plate. When the contact between the welding wire at the tip of the welding torch and the metal plate is detected by the detection device in the movement in each direction, the movement of the welding torch is stopped and the tip position of the welding torch is stored. While performing a calibration process for setting a reference position for detecting a displacement of the welding torch from a plurality of welding torch tip positions stored in the movement in each direction,
In a state where the calibration process is completed, a current position acquisition process is performed in which the welding torch is operated and the tip position of the welding torch is stored in the same manner as the calibration process, and is obtained by the reference position and the current position acquisition process. An arc welding apparatus for detecting whether or not the welding torch is displaced from the position. In the calibration process and the current position acquisition process, when the welding torch is moved in each of the positive and negative directions of the X-axis and Y-axis of the orthogonal coordinate system defined for the metal plate, first, the space portion of the metal plate is The welding torch is moved in the positive direction of the X-axis of the Cartesian coordinate system until it comes into contact with the inner edge, and when the contact between the welding wire at the tip of the welding torch and the metal plate is detected, the movement of the welding torch is stopped and the movement is stopped. The tip position of the welding torch is stored as the first position,
Subsequently, when the welding torch is moved in the negative direction of the X axis of the orthogonal coordinate system until it contacts the inner edge of the space portion of the metal plate, and the contact between the welding wire at the tip of the welding torch and the metal plate is detected, Stopping the movement of the welding torch and storing the welding torch tip position as a second position;
The midpoint between the first position and the second position is obtained, the welding torch is moved to the midpoint, and the Y axis of the orthogonal coordinate system is moved from the midpoint to the inner edge of the space portion of the metal plate. Moving the welding torch in the forward direction, detecting the contact between the welding wire at the tip of the welding torch and the metal plate, stopping the movement of the welding torch and storing the position of the tip of the welding torch as a third position;
Subsequently, when the welding torch is moved in the negative direction of the Y axis of the orthogonal coordinate system until it contacts the inner edge of the space portion of the metal plate, and the contact between the welding wire at the tip of the welding torch and the metal plate is detected, 2. The movement of the welding torch is stopped, the tip position of the welding torch is stored as a fourth position, and a fifth position which is a midpoint between the third position and the fourth position is obtained. Arc welding equipment. The robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance,
The operation program includes the X-axis of the orthogonal coordinate system defined on the metal plate and the welding torch in a state where the attitude of the welding torch is parallel to the Z-axis of the orthogonal coordinate system defined on the metal plate, and The Y-axis is moved in each of positive and negative directions, and when contact with the metal plate is detected in the movement in each direction, the movement of the welding torch is stopped and the tip position of the welding torch is stored. Item 3. An arc welding apparatus according to item 1 or 2. The robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance,
The operation program is configured such that the welding torch is tilted with respect to the Z axis of the orthogonal coordinate system defined on the metal plate while the welding torch is tilted with respect to the X axis and Y of the orthogonal coordinate system defined on the metal plate. The shaft is moved in each of positive and negative directions, and when contact with the metal plate is detected in the movement in each direction, the movement of the welding torch is stopped and the tip position of the welding torch is stored. The arc welding apparatus according to 1 or 2. The robot controller performs the calibration process and the current position acquisition process according to an operation program taught in advance,
The operation program includes the X-axis of the orthogonal coordinate system defined on the metal plate and the welding torch in a state where the attitude of the welding torch is parallel to the Z-axis of the orthogonal coordinate system defined on the metal plate, and The Y-axis is moved in each of the positive and negative directions, and when contact with the metal plate is detected in the movement in the respective directions, the movement of the welding torch is stopped and the tip position of the welding torch is stored. Moving the welding torch in the positive and negative directions of the X axis and Y axis of the orthogonal coordinate system defined on the metal plate in a state in which the posture is inclined with respect to the Z axis of the orthogonal coordinate system defined on the metal plate; 3. The device according to claim 1, wherein when the contact with the metal plate is detected in the movement in each direction, the movement of the welding torch is stopped and the tip position of the welding torch is stored. Click welding equipment.   The robot controller includes a storage unit that stores the fifth position determined in the calibration process as the reference position, and the reference position stored in the storage unit and the current position acquisition process The presence or absence of misalignment is detected based on a difference from the fifth position, and when the difference is larger than a preset allowable value, information on occurrence of misalignment is output to the outside. Arc welding equipment.   7. The arc welding apparatus according to claim 6, wherein when the difference is larger than a preset allowable value, the robot controller displays a message of occurrence of misalignment by a teaching device connected to the robot controller. .   The arc welding apparatus according to claim 6, wherein the robot controller outputs a signal to a warning lamp connected to the robot controller when the difference is larger than a preset allowable value.   The robot controller performs authentication of an operator when storing the fifth position in the storage unit, and stores the fifth position in the storage unit only when the authentication is completed. 6. The arc welding apparatus according to 6.   6. The arc according to claim 3, wherein the robot controller executes the current position acquisition process according to the operation program during continuous operation of the robot, and detects presence / absence of a position shift. Welding equipment.

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