Welding systems and welding methods

Abstract

To provide a welding system that is enabled to accurately weld a workpiece while simplified in teaching.SOLUTION: In a welding system according to the invention, a first teaching point TP2 is set above a weld start point WP2 in a welding portion of a workpiece W to be welded, and a second teaching point TP3 is set above a weld end point WP3 in the welding portion. Therein, a robot controller controls movement of an articulated robot such that, based on the first teaching point TP2 and the second teaching point TP3, a force detected by a force sensor maintains a specific value from the welding start point WP2 to the welding end point WP3, thereby separating a tip of the nozzle 21 from the welding portion, and moving the welding torch 2 while maintaining a distance from the tip 21 to the welding portion at a first distance.SELECTED DRAWING: Figure 6

Description

Technical Field

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[0005]

[0001] The present invention relates to a welding system and a welding method.

Background Art

[0002] A laser beam may be emitted from the nozzle of a welding torch attached to the tip of a robot arm to weld a workpiece. At this time, before welding the workpiece, the operator needs to perform teaching to instruct the welding position to a robot controller that controls the robot by bringing the tip of the nozzle into contact with a plurality of positions of the welding portion of the workpiece. Patent Document 1 describes teaching using a force sensor and a contact sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional teaching, it is necessary to align the position of the welding portion of the workpiece and the tip of the nozzle. Such teaching is complicated and a great burden on the operator. The emergence of a welding system and a welding method that can weld the workpiece accurately while simplifying the teaching is desired.

Means for Solving the Problems

[0005] A first aspect of one or more embodiments includes: a jointed robot to which a welding torch is attached and which moves the welding torch; a force sensor attached to the jointed robot for detecting the force acting on the welding torch that fluctuates with the movement of the welding torch; a laser oscillator for supplying a laser beam to the welding torch; a robot controller for controlling the movement of the jointed robot and outputting an ON operation signal to cause the laser beam to be emitted from the nozzle of the welding torch and an OFF operation signal to stop the emission of the laser beam from the nozzle; and a robot controller that causes the laser beam to be emitted from the nozzle in accordance with the ON operation signal and the OFF operation The welding system provides a robot controller that controls the emission of a laser beam from the nozzle in accordance with a signal, and the robot controller controls the movement of the articulated robot so that the force detected by the force sensor maintains a specific value from the welding start point to the welding end point, thereby moving the welding torch while keeping the tip of the nozzle away from the welding point and maintaining the distance from the tip to the welding point at a first distance, based on a first teaching point set above the welding start point at the welding location of the workpiece to be welded and a second teaching point set above the welding end point at the welding location.

[0006] According to the first aspect of one or more embodiments, teaching is easy because a first teaching point is set above the welding start point and a second teaching point is set above the welding end point at the welding location of the workpiece to be welded. According to the first aspect of one or more embodiments, the welding location is welded while maintaining the distance from the nozzle tip to the welding location at a first distance based on the force detected by the force sensor, making it possible to weld the workpiece with high precision.

[0007] A second aspect of one or more embodiments involves a robot controller controlling the movement of an articulated robot, controlling the articulated robot to move the tip of the nozzle of a welding torch attached to the articulated robot to a first teaching point located above the welding start point at the welding location of the workpiece to be welded, and controlling the articulated robot to lower the welding torch until the force acting on the welding torch, which fluctuates with the movement of the welding torch as detected by a force sensor attached to the articulated robot, reaches a specific value, thereby positioning the tip of the nozzle at a beam emission start position separated by a first distance from the welding start point, and the beam emission The present invention provides a welding method in which a laser oscillator is controlled to start emitting a laser beam from the nozzle at a starting position, and the force detected by the force sensor maintains the specified value, thereby moving the welding torch so that the distance from the tip of the nozzle emitting the laser beam to the welding location is maintained at the first distance, and the articulated robot is controlled so that the tip moves from the beam emission start position to a beam emission stop position below a second teaching point located above the welding end point at the welding location, and the laser oscillator is controlled to stop emitting the laser beam from the nozzle at the beam emission stop position.

[0008] According to a second aspect of one or more embodiments, teaching is easy because a first teaching point is set above the welding start point and a second teaching point is set above the welding end point at the welding location of the workpiece to be welded. According to a second aspect of one or more embodiments, the welding location is welded while maintaining the distance from the nozzle tip to the welding location at a first distance based on the force detected by the force sensor, making it possible to weld the workpiece with high precision. [Effects of the Invention]

[0009] According to one or more embodiments of the welding system and welding method, workpieces can be welded with high precision while simplifying the teaching process. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing a welding system according to one or more embodiments. [Figure 2] Figure 2 is a perspective view showing a welding system according to one or more embodiments. [Figure 3] Figure 3 is a perspective view showing a welding torch used in a welding system according to one or more embodiments. [Figure 4] Figure 4 shows an example of teaching in a welding system according to one or more embodiments. [Figure 5] Figure 5 is a partially enlarged view of an example of teaching in a welding system according to one or more embodiments. [Figure 6] Figure 6 shows a welding process in which an articulated robot moves a welding torch based on a plurality of teaching points set by teaching to weld a workpiece, in a welding system according to one or more embodiments. [Figure 7] Figure 7 shows a welding process in which an articulated robot moves a welding torch based on a plurality of teaching points set by teaching, in a welding system according to one or more embodiments, as viewed from the side. [Figure 8] Figure 8 is a perspective view showing a workpiece welded by a welding system according to one or more embodiments. [Figure 9] Figure 9 is a flowchart showing a welding method according to one or more embodiments. [Figure 10A] Figure 10A shows welding along a curved surface of a workpiece by a welding system according to one or more embodiments. [Figure 10B] Figure 10B shows a comparative example where welding along the curved surface of the workpiece is not possible. [Modes for carrying out the invention]

[0011] A welding system according to one or more embodiments comprises an articulated robot, a force sensor, a laser oscillator, a robot controller, and a control device. A welding torch is attached to the articulated robot, and the robot moves the welding torch. A force sensor is attached to the articulated robot and detects the force acting on the welding torch that fluctuates as the welding torch moves. A laser oscillator supplies a laser beam to the welding torch. The robot controller controls the movement of the articulated robot and outputs an ON operation signal to emit a laser beam from the nozzle of the welding torch and an OFF operation signal to stop the emission of the laser beam from the nozzle. The control device controls the emission of the laser beam from the nozzle according to the ON operation signal and the emission of the laser beam from the nozzle according to the OFF operation signal.

[0012] The robot controller controls the movement of the articulated robot so that, based on a first teaching point set above the welding start point at the welding location of the workpiece to be welded, and a second teaching point set above the welding end point at the welding location, the force detected by the force sensor maintains a specific value from the welding start point to the welding end point, thereby moving the welding torch while keeping the tip of the nozzle away from the welding location and maintaining the distance from the tip to the welding location at a first distance.

[0013] In one or more embodiments of the welding method, a robot controller that controls the movement of an articulated robot controls the articulated robot to move the tip of the nozzle of a welding torch attached to the articulated robot to a first teaching point located above the welding start point at the welding location of the workpiece to be welded. In one or more embodiments of the welding method, the robot controller controls the articulated robot to lower the welding torch until the force acting on the welding torch, which fluctuates with the movement of the welding torch as detected by a force sensor attached to the articulated robot, reaches a specific value, thereby positioning the tip of the nozzle at a beam emission start position separated by a first distance from the welding start point.

[0014] In the welding method according to one or more embodiments, the robot controller controls the laser oscillator to start the emission of the laser beam from the nozzle at the beam emission start position. In the welding method according to one or more embodiments, the robot controller moves the welding torch while maintaining the distance from the tip of the nozzle that emits the laser beam to the welding location at a first distance by maintaining the force detected by the force sensor at a specific value, and welds the welding location. The robot controller controls the articulated robot to move from the beam emission start position to the beam emission stop position below the second teaching point located above the welding end point at the welding location, where the tip is located. In the welding method according to one or more embodiments, the robot controller controls the laser oscillator to stop the emission of the laser beam from the nozzle at the beam emission stop position.

[0015] Hereinafter, the welding system and the welding method according to one or more embodiments will be specifically described with reference to the accompanying drawings.

[0016] The configuration of the welding system 100 according to one or more embodiments will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic configuration diagram showing the welding system 100, and FIG. 2 is a perspective view showing the welding system 100. FIG. 3 shows the welding torch 2 used in the welding system 100.

[0017] As shown in FIGS. 1 and 2, the welding system 100 includes a hand-held laser welder 1, a welding torch 2, an articulated robot 3, a force sensor 4, a robot controller 5, a control device 6, and a display 7. The robot controller 5 can be configured by, for example, a NC (Numerical Control) device. The control device 6 may be configured by a circuit or may be configured by a PLC (Programmable Logic Controller).

[0018] As shown in Figure 2, a table 200 on which the workpiece W to be welded is placed is positioned adjacent to the articulated robot 3 and the robot controller 5. The workpiece W consists of at least two sheet metal pieces to be welded together. The operator 300, wearing a protective face shield 310, sets multiple teaching points for moving the articulated robot 3 through teaching described later, before welding the workpiece W.

[0019] The handheld laser welding machine 1 is used when an operator 300 holds a welding torch 2 by hand and welds any workpiece. The welding torch 2 used with the handheld laser welding machine 1 can be attached to the tip of the arm of an articulated robot 3 by a torch operating device 20. A force sensor 4 is attached to the arm of the articulated robot 3. The articulated robot 3 is, for example, a 6-axis robot. The force sensor 4 detects the force applied to the welding torch 2 as it moves.

[0020] As shown in Figure 3, the tip of the welding torch 2 is provided with a nozzle 21 that emits a laser beam or guide light. The welding torch 2 is equipped with an ejection button for emitting the laser beam. The torch operating device 20 has a mechanism for fixing the welding torch 2 to the articulated robot 3 and a mechanism for pressing the ejection button.

[0021] As shown in Figure 1, the handheld laser welding machine 1 includes a laser oscillator 11 and a shielding gas supply device 12. The laser oscillator 11 has a guide light source 111 for emitting guide light. The laser oscillator 11 and the welding torch 2 are connected by an optical fiber 101 for transmitting the laser beam or guide light. The shielding gas supply device 12 and the welding torch 2 are connected by a shielding gas supply pipe 102 for supplying shielding gas. The welding torch 2 and the handheld laser welding machine 1 are further connected by a torch signal line 103.

[0022] When the ejection button of the welding torch 2 is operated by the operator 300, or when the ejection button is operated by the control device 6 as described later, a request signal requesting the ejection of a laser beam is supplied from the welding torch 2 to the handheld laser welding machine 1 via the torch signal line 103. When the request signal is input to the handheld laser welding machine 1, the laser oscillator 11 supplies a laser beam to the welding torch 2 via the optical fiber 101. When the nozzle 21 comes into contact with the workpiece W, a contact detection signal may be supplied from the welding torch 2 to the handheld laser welding machine 1 via the torch signal line 103.

[0023] Operator 300 performs teaching, setting teaching points corresponding to the welding locations on the workpiece W, as described later. The robot controller 5 creates a machining program to move the articulated robot 3 based on the teaching points set during teaching, and controls the movement of the articulated robot 3 according to the machining program.

[0024] The robot controller 5 and the control device 6 are connected by a torch operation signal line 105, and the control device 6 and the welding torch 2 are connected by a torch operation signal line 106. The robot controller 5 supplies an ON operation signal to the control device 6 via the torch operation signal line 105, which is set in accordance with the teaching point (ON command teaching point) that commands the robot controller to turn on the laser beam emission set in the teaching process, and which is the beam emission start position described later, in which the ejection button is pressed. The control device 6 supplies the ON operation signal supplied from the robot controller 5 to the welding torch 2 via the torch operation signal line 106.

[0025] As a result, the ejection button on the welding torch 2 is pressed, and a request signal is sent to the handheld laser welding machine 1 requesting the ejection of a laser beam, causing the laser beam to be ejected from the nozzle 21.

[0026] The robot controller 5 supplies an off operation signal to the control device 6 via the torch operation signal line 105, which releases the press of the eject button at the beam ejection stop position (described later) that corresponds to the teaching point (off command teaching point) that has been set to turn off the laser beam ejection set during teaching. The control device 6 supplies the off operation signal supplied from the robot controller 5 to the welding torch 2 via the torch operation signal line 106. As a result, the press of the eject button on the welding torch 2 is released, and the ejection of the laser beam from the nozzle 21 stops.

[0027] Thus, the robot controller 5 indirectly controls the laser oscillator 11 to start emitting the laser beam from the nozzle 21 at the beam emission start position, and indirectly controls the laser oscillator 11 to stop emitting the laser beam at the beam emission stop position. The robot controller 5 may also be configured to directly control the laser oscillator 11 to start emitting the laser beam from the nozzle 21 at the beam emission start position, and to directly control the laser oscillator 11 to stop emitting the laser beam at the beam emission stop position.

[0028] The robot controller 5 and the display unit 7 are connected by a display signal line 107. The display unit 7 displays the processing program created by the robot controller 5 and the status of the articulated robot 3. Note that the display unit 7 is not an essential component of the welding system 100 according to one or more embodiments. The control device 6 and the handheld laser welding machine 1 are connected by a control signal line 104. The control device 6 has a built-in safety circuit and, when an abnormality occurs in the articulated robot 3, supplies a control signal to the laser oscillator 11 via the control signal line 104 to stop the laser oscillator 11.

[0029] Figures 4 and 5 will be used to specifically explain the teaching process used by operator 300 to indicate the welding locations on the workpiece W. Figure 4 shows an example of teaching in the welding system 100, and Figure 5 shows a partially enlarged view of the same example. Although not shown in Figure 2, the welding system 100 is enclosed by partitions.

[0030] The handheld laser welding machine 1 is equipped with a safety device. The protective face shield 310 has a built-in capacitive proximity sensor. When the operator 300 puts on the protective face shield 310, the proximity sensor detects the operator 300's forehead at close range. This allows the proximity sensor to detect that the protective face shield 310 is attached to the operator 300, and the protective face shield 310 transmits a signal to the handheld laser welding machine 1 wirelessly or via a wired connection indicating that it is attached to the operator 300. The protective face shield 310 may also detect that it is attached to the operator 300 by a sensor that detects when the visor is down.

[0031] The partition door is equipped with a sensor to detect whether it is open or closed. A signal indicating whether the door is open or closed is transmitted via wire to the handheld laser welding machine 1. The handheld laser welding machine 1 is configured to release the safety device and emit guide light from the nozzle 21 of the welding torch 2 when the control device 6 has not detected any abnormality in the articulated robot 3, the operator 300 is wearing the protective face shield 310, and the partition door is closed.

[0032] As shown in Figure 4, the workpiece W consists of sheet metal pieces W1 and W2 to be welded together, and the welding area is a straight line from the welding start point WP2 at the left end to the welding end point WP3 at the right end. The operator 300 manually moves the welding torch 2 to set the first teaching point TP1 as the position of the tip of the nozzle 21 at a predetermined position in the upper left of the workpiece W. When the operator 300 presses the registration button provided on the articulated robot 3, the position of the tip of the nozzle 21 at that time is registered as teaching point TP1, and a movement command to move the welding torch 2, which is in the predetermined position, to teaching point TP1 is inserted into the processing program.

[0033] Next, the operator 300 positions the tip of the nozzle 21 above the welding start point WP2 to set the second teaching point TP2 (the first teaching point). By pressing the registration button, the operator 300 registers the teaching point TP2, and a movement command to move the welding torch 2 to the teaching point TP2 is inserted into the processing program. The operator 300 uses the command creation function of the articulated robot 3 to command the teaching point TP2 as the teaching point to start the emission of the laser beam. The teaching point TP2 will be referred to as the ON command teaching point.

[0034] As described later, laser beam emission does not begin when the tip of the nozzle 21 moves to the teaching point TP2, but rather when the tip of the nozzle 21 has descended toward the welding start point WP2 until the value of the force sensor 4 reaches a threshold. When teaching point TP2 is set as the ON command teaching point, a movement command to move the welding torch 2 to teaching point TP2 is followed by a command to descend the welding torch 2 until the value of the force sensor 4 reaches a threshold, and a command to turn on laser beam emission once the descent of the welding torch 2 is complete.

[0035] As shown in Figure 5, guide light Lg is emitted from the tip of the nozzle 21. The position where the nozzle 21 irradiates the workpiece W with guide light Lg is the same as the position where the nozzle 21 irradiates the workpiece W with a laser beam. The operator 300 sets the teaching point TP2 by positioning the welding torch 2 so that the guide light Lg is irradiated onto the welding start point WP2, with the tip of the nozzle 21 separated from the workpiece W by a predetermined distance. By determining the position of the welding start point WP2 using the guide light Lg and setting the teaching point TP2, the teaching point TP2 and the welding start point WP2 face each other at the same planar position in two planes that are different in height.

[0036] Furthermore, in Figure 4, the operator 300 positions the welding torch 2 so that the guide light Lg is irradiated onto the welding end point WP3, with the tip of the nozzle 21 separated from the workpiece W by a predetermined distance, and sets the third teaching point TP3 (second teaching point). By determining the position of the welding end point WP3 using the guide light Lg and setting the teaching point TP3, the teaching point TP3 and the welding end point WP3 face each other at the same planar position in two planes that are different in the height direction. The operator 300 commands the teaching point TP3 as the teaching point to terminate the emission of the laser beam. The teaching point TP3 will be referred to as the off-command teaching point.

[0037] The teaching point TP3 is registered when the operator 300 presses the registration button. Once teaching point TP3 is registered, a command is inserted into the processing program to move the welding torch 2 from a position close to the welding start point WP2 to a position close to the welding end point WP3, while maintaining a constant distance from the workpiece W based on the value of the force sensor 4, and to turn off the laser beam emission. Note that the distance from the workpiece W to the tip of the nozzle 21 at teaching point TP2 does not need to be the same as the distance from the workpiece W to the tip of the nozzle 21 at teaching point TP3.

[0038] Finally, the operator 300 sets a fourth teaching point TP4 in a predetermined position in the upper right of the workpiece W. When the operator 300 presses the register button, teaching point TP4 is registered, and a command to move the welding torch 2 from a position close to the welding end point WP3 to teaching point TP4 is inserted into the machining program. The operator 300 only needs to set up a number of teaching points, including at least an ON command teaching point TP2 and an OFF command teaching point TP3.

[0039] In addition to setting the teaching points TP1 to TP4 as described above, operator 300 sets a threshold value for the magnitude of the force detected by force sensor 4 in robot controller 5.

[0040] As described above, once the operator 300 sets the teaching point TP1 where the welding torch 2 will first be positioned when it starts moving, the ON command teaching point TP2, the OFF command teaching point TP3, the last teaching point TP4, and the threshold values ​​for the force sensor 4, the robot controller 5 creates the following processing program. The robot controller 5 controls the articulated robot 3 according to the processing program and controls the laser oscillator 11 via the control device 6, thereby properly welding the welding area from the welding start point WP2 to the welding end point WP3 at the right end of the workpiece W.

[0041] The first command is to move the welding torch 2, which is in a predetermined position, so that the tip of the nozzle 21 is located at the teaching point TP1. The second command is to move the tip of the nozzle 21 from the teaching point TP1 to the ON command teaching point TP2. The third command is to lower the tip of the nozzle 21 vertically downward from the ON command teaching point TP2 until the value of the force sensor 4 reaches a threshold. Once the tip of the nozzle 21 has lowered, the fourth command is to start outputting an ON operation signal to press the ejection button on the torch operating device 20.

[0042] The fifth command is to move the tip of the nozzle 21 along the welding area from a position below the ON command teaching point TP2 to a position below the OFF command teaching point TP3. The sixth command is to output an OFF operation signal to release the injection button at a position below the OFF command teaching point TP3. The seventh command is to move the tip of the nozzle 21 from a position below the OFF command teaching point TP3 to teaching point TP4.

[0043] The robot controller 5 creates a processing program that includes the first to seventh commands described above. To weld the welding points on the workpiece W, the operator 300 instructs the robot controller 5 to execute the processing program. Then, as shown in Figure 6, the robot controller 5 controls the articulated robot 3 so that the tip of the nozzle 21 is positioned sequentially at teaching point TP1 and the on-command teaching point TP2. With the tip of the nozzle 21 positioned at the on-command teaching point TP2, the robot controller 5 lowers the welding torch 2 vertically downward. Figure 6 shows the welding process in which the articulated robot 3 moves the welding torch 2 based on the teaching points TP1 to TP4 set during teaching to weld the welding points on the workpiece W.

[0044] Figure 7 shows the welding process viewed from the side. As shown in Figure 7, as the tip of the nozzle 21 approaches the workpiece W, the value of the force sensor 4 reaches a threshold position Pon, and the robot controller 5 stops the descent of the welding torch 2. At this point, the robot controller 5 starts supplying an ON operation signal to the control device 6, and the control device 6 supplies an ON operation signal to the welding torch 2, causing the ejection button to be pressed. This sends a request signal to the handheld laser welding machine 1 requesting the ejection of the laser beam, so that the ejection of the guide light Lg stops at position Pon and the ejection of the laser beam begins. Position Pon will be referred to as the beam ejection start position.

[0045] During the period when the welding torch 2 is emitting a laser beam, shielding gas is supplied to the welding torch 2 from the shielding gas supply device 12. Therefore, as the laser beam is emitted from the tip of the nozzle 21, shielding gas is also ejected from the tip of the nozzle 21.

[0046] The robot controller 5 controls the articulated robot 3 to move the tip of the nozzle 21 from the beam emission start position Pon to the position Poff below the off command teaching point TP3, while maintaining the distance from the tip of the nozzle 21 to the workpiece W, so as to keep the value of the force sensor 4 at a threshold. When the tip of the nozzle 21 reaches position Poff, the robot controller 5 supplies an off operation signal to the control device 6, and the control device 6 supplies an off operation signal to the welding torch 2, releasing the ejection button. As a result, an instruction signal to stop the ejection of the laser beam is supplied to the handheld laser welding machine 1, and the ejection of the laser beam is stopped at position Poff. Position Poff will be referred to as the beam emission stop position.

[0047] The threshold value of the force sensor 4 is a value used to fix the force detected by the force sensor 4 to a specific value when moving the tip of the nozzle 21 from the beam ejection start position Pon to the beam ejection stop position Poff. Furthermore, the threshold value of the force sensor 4 is a value used to maintain a predetermined constant distance from the tip of the nozzle 21 to the workpiece W when moving the tip of the nozzle 21 from the beam ejection start position Pon to the beam ejection stop position Poff. The threshold value of the force sensor 4 should be set in the machining program so that the distance from the tip of the nozzle 21 to the workpiece W is an appropriate distance.

[0048] The nozzle 21 that emits the laser beam moves from the beam emission start position Pon to the beam emission stop position Poff while maintaining a predetermined distance from the tip of the nozzle 21 to the workpiece W, so that the welding area of ​​the workpiece W is welded as shown in Figure 8. Figure 8 shows the welded workpiece W. When the tip of the nozzle 21 reaches the beam emission stop position Poff and the emission of the laser beam stops, the robot controller 5 controls the articulated robot 3 to move the tip of the nozzle 21 from the beam emission stop position Poff to the teaching point TP4, as shown in Figure 6.

[0049] A welding method according to one or more embodiments performed by the welding system 100 will be explained using the flowchart shown in Figure 9. Before the robot controller 5 performs the process shown in Figure 9, multiple teaching points are set by the teaching described above. In the example shown in Figure 6, the multiple teaching points are teaching points TP1 to TP4.

[0050] In Figure 9, when the robot controller 5 starts the operation of welding the workpiece W with the welding system 100, the robot controller 5 resets the force sensor 4 in step S1. In step S2, the robot controller 5 moves the tip of the nozzle 21 of the welding torch 2 to the ON command teaching point. In the example shown in Figure 6, the teaching point TP2 is the ON command teaching point. In step S3, the robot controller 5 starts lowering the welding torch 2.

[0051] In step S4, the robot controller 5 determines whether the value of the force sensor 4 is above a threshold. If the value of the force sensor 4 is not above the threshold (NO), the robot controller 5 repeats the process in step S4. If the value of the force sensor 4 is above the threshold (YES), the robot controller 5 finishes lowering the welding torch 2 in step S5. At this time, the tip of the nozzle 21 reaches the beam emission start position. In the example shown in Figure 6, the position Pon shown in Figure 7 is the beam emission start position.

[0052] In step S6, the robot controller 5 starts the emission of the laser beam. Subsequently, in step S7, the robot controller 5 moves the tip of the nozzle 21 of the welding torch 2 to the beam emission stop position below the off command teaching point. In the example shown in Figure 6, the position Poff shown in Figure 7 is the beam emission stop position. As described above, while the tip of the nozzle 21 moves from the beam emission start position to the beam emission stop position, the distance from the tip of the nozzle 21 to the workpiece W is controlled to a constant distance so that the value of the force sensor 4 becomes a specific value determined by a threshold.

[0053] In step S8, the robot controller 5 terminates the emission of the laser beam. In step S9, the robot controller 5 moves the tip of the nozzle 21 of the welding torch 2 to the final teaching point, thereby ending the process. In the example shown in Figure 6, teaching point TP4 is the final teaching point.

[0054] In Figures 6 and 7, the distance from the tip of the nozzle 21 to the workpiece W, which is maintained during welding from the welding start point WP2 to the welding end point WP3, is defined as the first distance. In Figure 4, when the operator 300 sets teaching point TP2 above the welding start point WP2, teaching point TP2 should be set at a position where the tip of the nozzle 21 is separated from the workpiece W by a second distance, which is longer than the first distance. Similarly, when the operator 300 sets teaching point TP3 above the welding end point WP3, teaching point TP3 should be set at a position where the tip of the nozzle 21 is separated from the workpiece W by a third distance, which is longer than the first distance. The second distance and the third distance may be the same or different.

[0055] As described above, according to the welding system 100 and welding method of one or more embodiments, it is not necessary to match the position of the welding location on the workpiece W with the position of the tip of the nozzle 21 during teaching. Since it is sufficient to set the teaching point at a predetermined height away from the workpiece W, teaching is easy. Furthermore, since the welding location is welded while maintaining a constant distance between the tip of the nozzle 21 and the welding location based on the force detected by the force sensor 4 applied to the welding torch 2, it is possible to weld the workpiece W with high precision.

[0056] According to one or more embodiments of the welding system 100 and welding method, even if the workpiece W is curved or warping occurs on the surface of the workpiece W due to heat input from laser beam irradiation, it is possible to weld the welding point while maintaining a constant distance between the tip of the nozzle 21 and the welding point. Figure 10A shows a state in which the workpiece W is a curved surface and teaching points TP2 and TP3 are set on the curved surface in the same manner as in Figures 4 and 6, and the workpiece W is welded by the welding system 100. Figure 10B is a comparative example, showing a case in which the workpiece W is a curved surface and teaching points TP2' and TP3' are set to contact the curved surface.

[0057] In Figure 10B, the straight line connecting teaching point TP2' and teaching point TP3' interferes with the workpiece W, so the straight line connecting teaching point TP2' and teaching point TP3' cannot be used as the welding trajectory. On the other hand, in Figure 10A, teaching points TP2 and TP3 are set at a distance from the surface of the workpiece W, and the workpiece W is welded while maintaining a constant distance between the tip of the nozzle 21 and the surface of the workpiece W. Therefore, the welding trajectory does not interfere with the workpiece W, and it is possible to weld accurately even if the workpiece W is a curved surface.

[0058] The present invention is not limited to the one or more embodiments described above, and can be modified in various ways without departing from the spirit of the invention. [Explanation of Symbols]

[0059] 1. Handheld laser welding machine 2 Welding torch 3. Articulated robots 4. Force sensor 5. Robot Controller 6. Control device 7 Display 11. Laser Oscillator 12 Shielding gas supply device 20 Torch operating device 21 nozzles 101 Optical Fiber 102 Shielding gas supply pipe 103 Torch signal wire 104 Control signal line 105, 106 Torch operation signal lines 107 Indicator signal line 300 Operators 310 Protective Face Pon Beam Emission Start Position Poff beam emission stop position TP1~TP4 Teaching Points Double job W1, W2 Sheet Metal WP2 welding start point WP3 Welding End Point

Claims

1. A welding torch is attached to a multi-joint robot that moves the welding torch, A force sensor attached to the articulated robot detects the force applied to the welding torch, which fluctuates as the welding torch moves. A laser oscillator that supplies a laser beam to the welding torch, A robot controller that controls the movement of the articulated robot and outputs an ON operation signal to emit a laser beam from the nozzle of the welding torch and an OFF operation signal to stop the emission of the laser beam from the nozzle, A control device that controls the emission of a laser beam from the nozzle in accordance with the ON operation signal and the emission of a laser beam from the nozzle in accordance with the OFF operation signal, Equipped with, The robot controller controls the movement of the articulated robot so that, based on a first teaching point set above the welding start point at the welding location of the workpiece to be welded, and a second teaching point set above the welding end point at the welding location, the force detected by the force sensor maintains a specific value from the welding start point to the welding end point, thereby moving the welding torch while keeping the tip of the nozzle away from the welding location and maintaining the distance from the tip to the welding location at a first distance. Welding system.

2. The aforementioned robot controller is A machining program is created to move the articulated robot based on a plurality of teaching points, including a first teaching point set above the welding start point and a second teaching point set above the welding end point, which are set during the pre-welding teaching of the welding location. In accordance with the processing program, after positioning the tip of the nozzle at the first teaching point, the welding torch is lowered until the force detected by the force sensor reaches the specified value, and the ON operation signal is supplied to the control device. According to the processing program, the control device is supplied with the off operation signal at the position where the force detected by the force sensor below the second teaching point reaches the specified value. The welding system according to claim 1.

3. The laser oscillator has a guide light source that emits guide light. During the teaching process, the welding torch emits the guide light from the nozzle. The first teaching point is a position where, with the guide light irradiating the welding start point, the tip of the nozzle is located at a distance from the welding start point that is longer than the first distance, The second teaching point is a position where, with the guide light irradiating the welding termination point, the tip of the nozzle is located at a third distance from the welding termination point that is longer than the first distance. The welding system according to claim 2.

4. A robot controller that controls the movement of a multi-joint robot, The articulated robot is controlled to move the tip of the nozzle of the welding torch attached to the articulated robot to a first teaching point located above the welding start point at the welding location of the workpiece to be welded. The articulated robot is controlled to lower the welding torch until the force acting on the welding torch, which fluctuates with the movement of the welding torch as detected by a force sensor attached to the articulated robot, reaches a specific value, thereby positioning the tip of the nozzle at a beam emission start position separated by a first distance from the welding start point. The laser oscillator is controlled to start emitting the laser beam from the nozzle at the aforementioned beam emission start position. The force detected by the force sensor maintains the specified value, thereby controlling the articulated robot so that the welding torch is moved so that the distance from the tip of the nozzle that emits the laser beam to the welding location maintains the first distance, and the welding location is welded, by moving the tip from the beam emission start position to the beam emission stop position below the second teaching point located above the welding end point at the welding location. The laser oscillator is controlled to stop the emission of the laser beam from the nozzle at the aforementioned beam emission stop position. Welding method.

5. In the pre-welding teaching of the aforementioned welding location, the welding torch is moved by hand to teach the robot controller the first and second teaching points. The aforementioned robot controller A machining program is created to move the articulated robot based on a plurality of teaching points, including the first and second teaching points. Control the articulated robot and the laser oscillator according to the processing program. The welding method according to claim 4.

6. When teaching the robot controller the first and second teaching points in the aforementioned teaching process, guide light is emitted from the nozzle. With the guide light irradiated onto the welding start point, the first teaching point is defined as a position where the tip of the nozzle is separated from the welding start point by a second distance that is longer than the first distance. With the guide light irradiating the welding termination point, the second teaching point is defined as a position where the tip of the nozzle is separated from the welding termination point by a third distance, which is longer than the first distance. The welding method according to claim 5.

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