Welding systems, programs, and welding methods

Abstract

To obtain good welding quality even when the center of curvature of the curved section differs between the steel pipe and the guide rail. [Solution] A welding system for controlling a welding robot that moves along a rail having straight rail sections and curved rail sections along a steel pipe and welds a first straight section, a curved section, and a second straight section of a steel pipe, wherein the center of curvature of the curved rail section is located closer to the center of the steel pipe than the center of curvature of the curved section, and the control unit controls the direction of the welding torch so that it is perpendicular to the first straight section of the steel pipe when the tip of the welding torch is welding the first straight section of the steel pipe up to the starting position of the curved section, controls the direction of the welding torch so that it is aligned with the normal direction of the curved section of the steel pipe when the tip of the welding torch is welding the curved section of the steel pipe, and controls the direction of the welding torch so that it is perpendicular to the second straight section of the steel pipe when the tip of the welding torch is welding the second straight section of the steel pipe from the ending position of the curved section.

Description

[Technical Field]

[0001] The present invention relates to a welding system, a program, and a welding method. [Background technology]

[0002] Large buildings such as skyscrapers use steel pipe columns formed by welding together rectangular steel pipes. As disclosed in Patent Document 1, a welding robot capable of circulating around the steel pipe along a guide rail is used to join the rectangular steel pipes. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-058078 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The corners of the steel pipe are curved in an arc shape. The corners of the guide rail are also formed to be curved in an arc shape. Since the guide rail is installed on the outside of the steel pipe, the circumferential length of the curved section of the steel pipe and the curved section of the guide rail are different. In Patent Document 1, the speed at which the welding robot travels along the guide rail is calculated in advance so that the movement speed of the tip of the welding torch along the curved section of the steel pipe is constant, and the welding robot is moved in accordance with this speed. This keeps the welding speed of the curved section of the steel pipe constant.

[0005] In many cases, the center of curvature of the curved section of the steel pipe differs from the center of curvature of the curved section of the guide rail. In this case, the distance between the steel pipe and the guide rail in the curved section is not constant in the circumferential direction. Therefore, in the method described in Patent Document 1, it is difficult to maintain a constant welding speed in the curved section of the steel pipe while keeping the distance between the tip of the welding torch and the welding site of the steel pipe constant. Furthermore, it is difficult to always point the tip of the welding torch perpendicular to the welding site of the steel pipe in the curved section. As a result, the quality of the weld may be reduced.

[0006] The present invention has been made in view of the circumstances described above, and aims to provide a welding system, program, and welding method that can obtain good welding quality even when the center of curvature of the curved section differs between the steel pipe and the guide rail. [Means for solving the problem]

[0007] A welding system according to a first aspect of the present invention is a welding system for controlling a welding robot that moves along a rail having a curved portion arranged along a steel pipe and welds the curved portion of the steel pipe, comprising: an acquisition unit that acquires the center of curvature of the curved portion of the steel pipe as a first center of curvature; and a setting unit that sets the welding conditions of the welding robot using the first center of curvature acquired by the acquisition unit, wherein the welding robot is equipped with a welding torch, and the welding conditions include the welding torch direction, which is the direction of the welding torch with respect to the curved portion of the steel pipe, and the welding conditions are set using the first center of curvature when the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide.

[0008] A welding system according to a second aspect of the present invention is a welding system for controlling a welding robot that moves along a rail having a curved portion arranged along a steel pipe and welds the curved portion of the steel pipe, comprising: an acquisition unit that acquires the center of curvature of the curved portion of the steel pipe as a first center of curvature; and a setting unit that sets the welding conditions of the welding robot using the first center of curvature acquired by the acquisition unit, wherein the welding robot is equipped with a welding torch, the welding conditions include the target position of the welding torch, and the welding conditions are set using the first center of curvature when the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide.

[0009] A welding system according to a third aspect of the present invention is a welding system according to the first or second aspect described above, wherein the welding conditions differ depending on whether the first center of curvature and the second center of curvature coincide.

[0010] A welding system according to a fourth aspect of the present invention further comprises a torch direction changing unit for changing the direction of the welding torch, wherein the setting unit sets the direction of the welding torch using the first curvature center and the second curvature center, and the torch direction changing unit changes the direction of the welding torch so that the direction of the welding torch with respect to the curved portion of the steel pipe matches the direction of the welding torch set by the setting unit.

[0011] A welding system according to a fifth aspect of the present invention is a welding system according to the first or fourth aspect described above, wherein the welding torch orientation includes the orientation of the welding torch when, in a top view, the orientation of the tip of the welding torch coincides with the normal direction of the curved portion of the steel pipe, and the setting unit sets the welding torch orientation according to the position of the welding robot.

[0012] A welding system according to a sixth aspect of the present invention is a welding system according to the fourth aspect, wherein the torch orientation changing unit includes a first rotation unit that can rotate the welding torch around a first axis parallel to the direction in which the welding robot moves, and a second rotation unit that can rotate the welding torch around a second axis parallel to the longitudinal direction of the steel pipe, wherein one of the first rotation unit and the second rotation unit rotates the other together with the welding torch, the welding torch orientation includes the orientation of the welding torch when the tip of the welding torch is located in the groove of the steel pipe as viewed along the direction in which the welding robot moves, and the setting unit sets the welding torch orientation in accordance with the rotation by the one.

[0013] A welding system according to a seventh aspect of the present invention is a welding system according to any one of the first to sixth aspects described above, wherein the welding conditions include a welding travel speed, which is the travel speed of the tip of the welding torch.

[0014] A welding system according to an eighth aspect of the present invention further comprises a speed changing unit for changing the movement speed of the welding robot, wherein the setting unit sets the welding movement speed using the first center of curvature and the second center of curvature, and the speed changing unit changes the movement speed of the welding robot so that the movement speed of the tip of the welding torch matches the welding movement speed set by the setting unit.

[0015] A welding system according to a ninth aspect of the present invention further comprises a robot position changing unit for changing the position of the welding robot, wherein the setting unit sets the welding movement speed using the first center of curvature and the second center of curvature, and the robot position changing unit changes the position of the welding robot so that the movement speed of the tip of the welding torch matches the welding movement speed set by the setting unit.

[0016] A welding system according to a tenth aspect of the present invention further comprises a torch position changing unit for changing the position of the welding torch, wherein the setting unit sets the target position using the first curvature center and the second curvature center, and the torch position changing unit changes the position of the welding torch so that the position of the welding torch coincides with the target position set by the setting unit.

[0017] A program according to the eleventh aspect of the present invention is a program for causing a computer to function as a welding system according to any one of the first to tenth aspects described above.

[0018] A welding method according to a twelfth aspect of the present invention is a welding method performed by a welding system that controls a welding robot that moves along a rail having a curved portion arranged along a steel pipe and welds the curved portion of the steel pipe, comprising: an acquisition step of acquiring the center of curvature of the curved portion of the steel pipe as a first center of curvature; and a setting step of setting welding conditions for the welding robot using the first center of curvature acquired in the acquisition step, wherein the welding conditions include a welding torch direction which is the direction of the welding torch of the welding robot with respect to the curved portion of the steel pipe, and in the setting step, if the first center of curvature and the second center of curvature which is the center of curvature of the curved portion of the rail do not coincide, the welding conditions are set using the first center of curvature.

[0019] A welding method according to a thirteenth aspect of the present invention is a welding method performed by a welding system that controls a welding robot that moves along a rail having a curved portion arranged along a steel pipe and welds the curved portion of the steel pipe, comprising: an acquisition step of acquiring the center of curvature of the curved portion of the steel pipe as a first center of curvature; and a setting step of setting welding conditions for the welding robot using the first center of curvature acquired in the acquisition step, wherein the welding conditions include the target position of the welding torch of the welding robot, and in the setting step, if the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide, the welding conditions are set using the first center of curvature.

[0020] A welding system according to a fourteenth aspect of the present invention is a welding system for controlling a welding robot that moves along a rail having a straight rail section and a curved rail section along a steel pipe and welds a first straight steel pipe section, a curved steel pipe section and a second straight steel pipe section of the steel pipe, comprising: a welding torch of the welding robot; a torch direction changing unit for changing the direction of the welding torch; and a control unit for controlling the torch direction changing unit, wherein the center of curvature of the curved steel pipe section is located closer to the center of the steel pipe than the center of curvature of the curved rail section, and The control unit is characterized in that, when the tip of the welding torch is welding the straight section of the first steel pipe up to the starting position of the curved section of the steel pipe, the direction of the welding torch is controlled to be perpendicular to the straight section of the first steel pipe; when the tip of the welding torch is welding the curved section of the steel pipe, the direction of the welding torch is controlled to be aligned with the normal direction of the curved section of the steel pipe; and when the tip of the welding torch is welding the straight section of the second steel pipe from the ending position of the curved section of the steel pipe, the direction of the welding torch is controlled to be perpendicular to the straight section of the second steel pipe.

[0021] A welding system according to a 15th aspect of the present invention is a welding system for controlling a welding robot that welds a first straight section, a curved section, and a second straight section of a steel pipe while moving in a predetermined direction along a rail having a first straight section, a curved section, and a second straight section of a steel pipe, the welding system comprising: a welding torch of the welding robot; a torch direction changing unit for changing the direction of the welding torch; and a control unit for controlling the torch direction changing unit, wherein the center of curvature of the curved section of the steel pipe is located closer to the center of the steel pipe than the center of curvature of the curved section of the rail, the curved section of the rail has a starting position, a starting position, a starting position, a finishing position, and an intermediate position between the starting position and the finishing position, and the curved section of the steel pipe has a starting position, a starting position, and an ending position, and the control unit controls the tip of the welding torch forward The welding robot is characterized in that, when welding the first straight section of the steel pipe to the starting position of the curved section of the steel pipe, the orientation of the welding torch is controlled to be perpendicular to the first straight section of the steel pipe; when the tip of the welding torch is welding the curved section of the steel pipe, the tilt of the welding torch toward the opposite side of the predetermined direction is controlled to increase as the welding robot moves along the first straight section of the rail to the starting position of the curved section of the rail; the tilt of the welding torch toward the opposite side of the predetermined direction is controlled to decrease as the welding robot moves from the starting position of the curved section of the rail to the middle position of the curved section of the rail; the tilt of the welding torch toward the predetermined direction is controlled to increase as the welding robot moves from the middle position of the curved section of the rail to the end position of the curved section of the rail; and the tilt of the welding torch toward the predetermined direction is controlled to decrease as the welding robot moves from the end position of the curved section of the rail to the second straight section of the rail.

[0022] A welding system according to a sixteenth aspect of the present invention is a welding system for controlling a welding robot that moves in a predetermined direction along a rail having a straight section and a curved section along a steel pipe and welds the straight section and the curved section of the steel pipe, the welding system comprising: a welding torch of the welding robot; a torch direction changing unit for changing the direction of the welding torch; a torch position changing unit for changing the position of the welding torch; and a control unit for controlling the torch direction changing unit and the torch position changing unit, wherein the center of curvature of the curved section of the steel pipe is located closer to the center of the steel pipe than the center of curvature of the curved section of the rail, the curved section of the rail has a starting position, a starting position, a starting position, a finishing position, and an intermediate position between the starting position and the ending position, and the control unit controls the tip of the welding torch when welding the curved section of the steel pipe. In this process, the welding robot is controlled to tilt the welding torch in the direction opposite to the predetermined direction as it moves along the straight section of the rail to the starting position of the rail curve, so that the welding torch approaches the steel pipe; as the welding robot moves from the starting position of the rail curve to the middle position of the rail curve, the tilt of the welding torch in the direction opposite to the predetermined direction decreases, so that the welding torch approaches the steel pipe; as the welding robot moves from the middle position of the rail curve to the ending position of the rail curve, the tilt of the welding torch in the direction opposite to the predetermined direction increases, so that the welding torch moves away from the steel pipe; and as the welding robot moves from the ending position of the rail curve along the straight section of the rail, the tilt of the welding torch in the direction opposite to the predetermined direction decreases, so that the welding torch moves away from the steel pipe. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a welding system, program, and welding method that can obtain good welding quality even when the circumferential length and center of curvature of the curved section differ between the steel pipe and the guide rail. [Brief explanation of the drawing]

[0024] [Figure 1]This is an overall diagram showing the welding system according to the first embodiment. [Figure 2] This is a block diagram illustrating the outline of the welding system according to the first embodiment. [Figure 3] This figure shows a welding robot according to the first embodiment, where (a) is a side view and (b) is a link diagram of (a). [Figure 4] This is a rear view of the welding robot according to the first embodiment. [Figure 5] (a) is a side view showing the first rotating part of the welding robot according to the first embodiment, and (b) is a top view showing the second rotating part of the welding robot. [Figure 6] This is a side view of a welding robot according to the first embodiment. [Figure 7] This figure shows the steel pipe and guide rail in the first embodiment, where (a) is a plan view and (b) is a link diagram of (a). [Figure 8] This is a diagram illustrating the welding of a curved section in the first embodiment. [Figure 9] This is a system block diagram of the system control device according to the first embodiment. [Figure 10] This is a system block diagram of the control unit of the system control device according to the first embodiment. [Figure 11] This flowchart shows an example of the flow of the welding process for curved sections performed by the system control device in the first embodiment. [Figure 12] This is a diagram illustrating the welding of a curved section in the second embodiment. [Figure 13] This flowchart shows an example of the flow of the welding process for curved sections performed by the system control device in the second embodiment. [Modes for carrying out the invention]

[0025] [First Embodiment] Hereinafter, a welding system 100 according to the first embodiment of the present invention will be described with reference to the drawings. As shown in Figure 1, the welding system 100 is used to weld the ends of steel pipes 8 that are arranged vertically side by side. The steel pipe 8 is a rectangular steel pipe having four arc-shaped curved sections 8a positioned at the corners and four straight sections 8b connecting the curved sections 8a to each other (continuing the curved sections 8a without interruption). The axis of the steel pipe 8 extends in the vertical direction. In the initial state, the steel pipe 8 is temporarily fixed by a construction jig 9. The construction jig 9 is attached to the straight sections 8b of the steel pipe 8.

[0026] [Overview of the welding system] First, the welding system 100 will be described with reference to Figures 1 and 2. The welding system 100 comprises a welding robot 1, a guide rail 2, a camera 3, a welding power supply 4, a wire feeder 5, and a system control device 6.

[0027] The welding robot 1 comprises multiple motors 32 and a welding torch 13. The welding robot 1 is also communicatively connected to a system control device 6. The welding robot 1 includes a relay panel (not shown) that receives control from the system control device 6. Motor 32 is a motor that drives the welding robot 1 under the control of the system control device 6. Motor 32 includes a servo motor (speed change unit, robot position change unit) that moves the welding robot 1 along the guide rail 2.

[0028] The welding torch 13 is used to weld the ends of the steel pipes 8 together. Welding with the welding torch 13 is performed, for example, by arc welding. A welding wire is placed inside the welding torch 13.

[0029] The guide rail 2 is positioned along the steel pipe 8. The guide rail 2 is arranged in a ring shape around the steel pipe 8 in the circumferential direction. The guide rail 2 has four arc-shaped curved sections 2a positioned at the corners and four straight sections 2b connecting the curved sections 2a to each other. The welding robot 1 is movable along the guide rail 2.

[0030] The imaging device 3 is attached to the welding robot 1. The imaging device 3 photographs the welding area of ​​the steel pipe 8 during the sensing process before welding. The imaging device 3 also photographs the welding process performed by the welding robot 1 during the welding process. The imaging device 3 is, for example, a camera. The imaging device 3 is connected to the system control unit 6 for communication, and the images or videos (hereinafter referred to as "imaging results") acquired by the imaging device 3 are transmitted to the system control unit 6.

[0031] The welding power supply 4 supplies power to the wire feeder 5. The wire feeder 5 supplies welding wire to the welding torch 13. The welding torch 13 is connected to the wire feeder 5 via a welding torch cable. The wire feeder 5 supplies power to the welding torch 13.

[0032] The system control device 6 controls the operation of the welding system 100. Specifically, the system control device 6 controls the operation of the welding robot 1, the welding power supply 4, and the wire feeder 5. The welding robot 1 is connected to the system control device 6 via a control cable. The control cable transmits signals from the system control device 6 to the welding robot 1, which are control signals for controlling the welding robot 1.

[0033] [Configuration of the welding robot] Next, the configuration of welding robot 1 will be explained with reference to Figures 3-5. Figure 3(a) is a side view of the welding robot 1. Figure 3(b) is a link diagram of Figure 3(a). Figure 4 is a rear view of the welding robot 1. Figure 5(a) is a side view of the welding robot 1 showing the first rotating part 35, which will be described later. Figure 5(b) is a top view of the welding robot 1 showing the second rotating part 36, which will be described later. Hereafter, the direction along the vertical will be referred to as the vertical direction x of the welding robot 1. The direction in which the welding robot 1 moves along the guide rail 2 will be referred to as the left-right direction y of the welding robot 1. The direction perpendicular to the vertical direction x and left-right direction y of the welding robot 1 will be referred to as the forward-backward direction z of the welding robot 1.

[0034] The welding robot 1 comprises a main body 11, a welding torch 13, and a support unit 14. The main body 11 is the base of the welding robot 1. The main body 11 is equipped with a motor 32. The main body 11 is equipped with a wheel section 12 that is attached to the guide rail 2. The welding robot 1 moves along the guide rail 2 by the wheel section 12 sliding on the guide rail 2.

[0035] The support section 14 is provided between the main body section 11 and the welding torch 13 and supports the welding torch 13. The support section 14 includes a case 21, a first link member 22, a second link member 23, and a third link member 24.

[0036] Case 21 is provided so as to cover the outside of the main body 11. Case 21 is movable relative to the main body 11 in the front-rear direction z of the welding robot 1. The main body 11 and case 21 constitute the front-rear movement section 33 (torch position changing section). In the link diagram shown in Figure 3(b), the front-rear movement section 33 is shown as a linear joint.

[0037] The first link member 22 comprises a vertical arm 22a extending vertically downward, a horizontal arm 22b extending horizontally from the lower end of the vertical arm 22a, and a connecting panel 22c connected to the horizontal arm 22b and extending vertically downward. The vertical arm 22a, the horizontal arm 22b, and the connecting panel 22c are connected to each other so that they cannot move relative to one another. The upper end of the vertical arm 22a is connected to the case 21 inside the case 21. The vertical arm 22a (first link member 22) is movable in the vertical x direction relative to the case 21 of the welding robot 1. The case 21 and the first link member 22 constitute the vertical movement section 34 (torch position changing section). In the link diagram shown in Figure 3(b), the vertical movement section 34 is shown as a linear joint.

[0038] The second link member 23 is panel-shaped. The upper end of the second link member 23 is connected to the lower end of the connecting panel 22c via the first link pin 351. As shown in Figure 5(a), the second link member 23 is rotatable relative to the connecting panel 22c around the central axis of the first link pin 351 (hereinafter also referred to as the first axis). The central axis of the first link pin 351 is parallel to the left-right direction y of the welding robot 1. The connecting panel 22c and the second link member 23 constitute the first rotating part 35 (torch direction changing part). In the link diagram shown in Figure 3(b), the first rotating part 35 is shown as a rotary joint. The first rotating part 35 rotates the second rotating part 36, which will be described later, together with the welding torch 13.

[0039] The third link member 24 is connected to the lower end of the second link member 23 via the second link pin 361. The third link member 24 is a holder on which the welding torch 13 is supported. As shown in Figure 5(b), the third link member 24 is rotatable relative to the second link member 23 around the central axis of the second link pin 361 (hereinafter also referred to as the second axis). When the second link member 23 is not rotated relative to the connecting panel 22c, the central axis of the second link pin 361 is parallel to the vertical x direction of the welding robot 1. The second link member 23 and the third link member 24 constitute the second rotating part 36 (torch direction changing part). In the link diagram shown in Figure 3(b), the second rotating part 36 is shown as a rotary joint.

[0040] The forward / backward moving section 33, the up / down moving section 34, the first rotating section 35, and the second rotating section 36 are all operated by the motor 32.

[0041] [Control method] A control method for a welding system 100 having the above configuration will be described. The control method according to this embodiment has a main feature in welding the steel pipe 8, specifically around the curved section 8a (hereinafter also simply referred to as welding the curved section 8a). The curved section 8a of the steel pipe 8 and the curved section 2a of the guide rail 2 have different lengths in the circumferential direction. Also, in many cases, the first curvature center C1 of the curved section 8a of the steel pipe 8 and the second curvature center C2 of the curved section 2a of the guide rail 2 are different. Therefore, the distance between the steel pipe 8 and the guide rail 2 in the curved sections 8a and 2a is not constant in the circumferential direction. In this embodiment, even in such cases, high-quality welding can be achieved regardless of the position of the steel pipe 8 by adjusting the amount of movement of the welding robot 1 according to the welding conditions.

[0042] Below, we will first explain the basic concept of the control method, referring to Figure 7. Figure 7(a) is a plan view showing the steel pipe 8 and the guide rail 2. Figure 7(b) is a link diagram of Figure 7(a).

[0043] The distance between the steel pipe 8 and the guide rail 2 varies depending on the position of each curved section 8a and 2a. Therefore, in this control method, the welding of the curved section 8a is divided into multiple areas, and the method for determining the amount of movement of the welding robot 1 is adjusted for each area. In order to divide the welding of the curved section 8a into multiple areas, a steel pipe coordinate system is defined based on the steel pipe 8. This steel pipe coordinate system is defined for each curved section 8a of the steel pipe 8. Hereinafter, the vertical direction will be referred to as the X direction in the steel pipe coordinate system. The direction perpendicular to the X direction and along one of the two straight sections 8b connected to one curved section 8a will be referred to as the Y direction in the steel pipe coordinate system. The direction perpendicular to both the X and Y directions will be referred to as the Z direction. The Z direction is the direction along the other straight section 8b of the two straight sections 8b mentioned above. For example, the origin of the steel pipe coordinate system is set to a position that coincides in the X direction with the position of the tip of the welding torch 13 (target position) that satisfies the welding conditions described later, and also coincides with the first curvature center C1 of the curved section 8a of the steel pipe 8 in a top view (YZ plane). Furthermore, within the X direction, the vertical upward direction is referred to as the +X direction, and the vertical downward direction is referred to as the -X direction. Within the Y direction, the direction toward the outside of the steel pipe 8, relative to the origin of the steel pipe coordinate system (first curvature center C1), is referred to as the +Y direction, and the direction toward the inside of the steel pipe 8 is referred to as the -Y direction. Within the Z direction, the direction toward the outside of the steel pipe 8, relative to the origin of the steel pipe coordinate system (first curvature center C1), is referred to as the +Z direction, and the direction toward the inside of the steel pipe 8 is referred to as the -Z direction.

[0044] [Curved section of steel pipe and curved section of guide rail] The curved section 8a of the steel pipe 8 and the curved section 2a of the guide rail 2 will be described below. Curved section 8a, in a top view (YZ plane), is a circular arc with a radius of Rc and centered at the first curvature center C1. Curved section 2a, in a top view, is a circular arc with a radius of Rg and centered at the second curvature center C2.

[0045] In this embodiment, the position of the first curvature center C1 is different from the position of the second curvature center C2. The second curvature center C2 is located closer to the center of the steel pipe 8 than the first curvature center C1. The distance between the straight section 8b of the steel pipe 8 and the straight section 2b of the guide rail 2 is l cg Therefore, the distance e in the Y direction (or Z direction) between the first curvature center C1 and the second curvature center C2 is expressed by the following formula. e = Rc + l cg -Rg In other words, the second center of curvature C2 is located at a position shifted by -e in both the Y and Z directions from the first center of curvature C1.

[0046] As shown in Figure 8, the welding of the steel pipe 8 is divided into Area 1, Area 2, Area 3, and Area 4, depending on the welding method. In the following, the starting position of the curved section 2a will be Pg1 and its ending position will be Pg2. The starting position of the curved section 8a will be Pc2 and its ending position will be Pc3. Position Pc1 is the intersection of the straight line connecting the second curvature center C2 and position Pg1 with the straight section 8b of the steel pipe 8. Position Pc4 is the intersection of the straight line connecting the second curvature center C2 and position Pg2 with the straight section 8b of the steel pipe 8.

[0047] Area 1 is the area where the steel pipe 8 is welded from position Pc1 to position Pc2. In other words, Area 1 is the area where the tip of the welding torch 13 moves from position Pc1 to position Pc2. In Area 1, the welding robot 1 moves along the curved section 2a of the guide rail 2 while welding the straight section 8b of the steel pipe 8. In other words, in Area 1, the welding robot 1 is positioned on the curved section 2a of the guide rail 2, and the part that the welding robot 1 welds is the straight section 8b of the steel pipe 8. Area 2 is the area where the steel pipe 8 is welded from position Pc2 to position Pc3. In other words, Area 2 is the area where the tip of the welding torch 13 moves from position Pc2 to position Pc3. In Area 2, the welding robot 1 moves along the curved section 2a of the guide rail 2 and welds the curved section 8a of the steel pipe 8. That is, in Area 2, the welding robot 1 is positioned on the curved section 2a of the guide rail 2, and the part that the welding robot 1 welds is the curved section 8a of the steel pipe 8. Area 3 is the area where the steel pipe 8 is welded from position Pc3 to position Pc4. In other words, Area 3 is the area where the tip of the welding torch 13 moves from position Pc3 to position Pc4. In Area 3, the welding robot 1 moves along the curved section 2a of the guide rail 2 while welding the straight section 8b of the steel pipe 8. That is, in Area 3, the welding robot 1 is positioned on the curved section 2a of the guide rail 2, and the part that the welding robot 1 welds is the straight section 8b of the steel pipe 8. Area 4 is the area of ​​the steel pipe 8 other than areas 1 to 3. In area 4, the welding robot 1 moves along the straight section 2b of the guide rail 2 and welds the straight section 8b of the steel pipe 8. In other words, in area 4, the welding robot 1 is positioned on the straight section 2b of the guide rail 2, and the part that the welding robot 1 welds is the straight section 8b of the steel pipe 8. In this embodiment, welding of the curved section 8a refers to welding of areas 1 to 3.

[0048] [Welding conditions] To ensure good welding quality, regardless of the area, the following are necessary: <1> ~ <4> It is preferable to satisfy the welding conditions shown. <1> The speed at which the tip of the welding torch 13 moves along the welding area of ​​the steel pipe 8 (hereinafter also referred to as the welding movement speed Vw) becomes constant. <2> The orientation of the welding torch 13 in a top view (hereinafter also referred to as the welding torch orientation) coincides with the normal direction of the curved portion 8a of the steel pipe 8, or is perpendicular to the straight portion 8b of the steel pipe 8. <3> The aiming angle θn of the welding torch 13 remains constant. The aiming angle θn of the welding torch 13 is the orientation of the welding torch 13 when its tip is positioned in the groove of the steel pipe 8, as viewed along the left-right direction y of the welding robot 1, as shown in Figure 6. The aiming angle θn is appropriately adjusted according to the condition of the welding area of ​​the steel pipe 8 (for example, groove information). <4> The distance between the tip of the welding torch 13 and the welding area of ​​the steel pipe 8 (hereinafter also referred to as the target position of the welding torch 13) is constant. Furthermore, the position of the tip of the welding torch 13 in the X direction is constant when the above welding conditions are met, and it coincides with the origin position of the steel pipe coordinate system in the X direction. As shown in Figure 6, H is the distance in the X direction (vertical direction x of the welding robot 1) between the position of the tip of the welding torch 13 in the X direction when the above welding conditions are met and the lower end 2c of the guide rail 2.

[0049] Here, in area 4, the distance between the steel pipe 8 (straight section 8b) and the guide rail 2 (straight section 2b) is constant. Therefore, the amount of movement of the welding robot 1 that satisfies the above welding conditions is uniformly determined. That is, the above welding conditions <2> ~ <4> With the welding torch direction, target angle, and target position of the welding torch 13 set to satisfy the above conditions, welding can be performed that satisfies the above welding conditions by moving the welding robot 1 at the welding movement speed Vw.

[0050] On the other hand, in areas 1 to 3, the distance between the steel pipe 8 and the guide rail 2 differs depending on the circumferential position, so the amount of movement of the welding robot 1 that satisfies the above welding conditions cannot be uniformly determined. In this embodiment, in welding in areas 1 to 3 (welding of the curved section 8a), inverse kinematics is used, The target position and target orientation of the welding torch 13 that satisfy the above welding conditions (hereinafter also referred to as the target position and orientation of the welding torch 13) are calculated, We will determine the amount of movement required for welding robot 1 to achieve this.

[0051] Specifically, the matrix U (as described above) represents the target position and target orientation of the welding torch 13 that satisfies the above welding conditions. This generates a matrix U that corresponds to the target position and target orientation of the welding torch 13 at the welding position at time t. The welding position at time t is determined by the welding conditions. <1> The welding movement speed Vw is used, and the determination is made based on Vw·t. For example, if the welding position at time 0 is Pc1, the magnitude of Vw·t can be used to determine which of areas 1 to 3 the welding position at time t is located in. Furthermore, a matrix T (as described above) represents the position and orientation of the welding torch 13 when the welding robot 1 moves by a predetermined amount. It generates (corresponding to). By determining the amount of movement of the welding robot 1 such that matrices U and T are equal, and controlling the drive of the motor 32 according to this amount of movement, welding that satisfies the above welding conditions can be performed. In other words, by making these matrices U and T equal, the amount of movement required to achieve the target position and orientation of the welding torch 13 at a predetermined time t (welding position) can be determined. By controlling the welding robot 1 to achieve this amount of movement, welding of good quality can be achieved.

[0052] [Regarding matrix U] The generation of matrix U will be explained in detail with reference to Figure 8. Matrix U is a matrix that represents the target position and orientation of the welding torch 13 that satisfies the above welding conditions, relative to the origin position (first curvature center C1) of the steel pipe coordinate system. Matrix U represents the target position and orientation of the welding torch 13 at a specific welding position. Matrix U is determined for each welding position of the steel pipe 8. Matrix U is determined regardless of the position of the welding robot 1. In this embodiment, welding of the straight section 8b is performed in areas 1 and 3, and welding of the curved section 8a is performed in area 2. Therefore, the target position and target orientation of the welding torch 13 that satisfy the above welding conditions are different in areas 1 to 3. For this reason, matrix U is generated for each of areas 1 to 3. As mentioned above, the position of the tip of the welding torch 13 in the X direction that satisfies the above welding conditions is constant and is a position that coincides with the origin position of the steel pipe coordinate system in the X direction.

[0053] In Area 1, the tip of the welding torch 13 moves from position Pc1 to position Pc2 at a welding speed Vw. The movement of the tip of the welding torch 13 in Area 1 is at a welding speed Vw in the Y direction (+Y direction). Therefore, the Y-direction position of the tip of the welding torch 13 varies with time. Taking the time when the tip of the welding torch 13 reaches position Pc1 as 0, the Y-direction position of the tip of the welding torch 13 at time t is the position moved by +Vw·t in the Y direction from position Pc1. Note that the Y-direction position of position Pc1 is the position moved by -e in the Y direction from the origin of the steel pipe coordinate system (first curvature center C1). Also, in Area 1, the Z-direction position of the tip of the welding torch 13 is always the position moved by +Rc in the Z direction from the origin of the steel pipe coordinate system (first curvature center C1). Furthermore, at the welding position at time t, the orientation of the welding torch 13 that satisfies the above welding conditions is perpendicular to the straight section 8b. At the welding position at time t, the aiming angle of the welding torch 13 is always constant (θn). At the welding position at time t, the distance between the tip of the welding torch 13 and the straight section 8b is always constant. Matrix U in Area 1 is generated as a homogeneous transformation matrix representing the position and orientation of the welding torch 13 as described above.

[0054] In area 2, the tip of the welding torch 13 moves from position Pc2 to position Pc3 at a welding speed Vw. In area 2, the tip of the welding torch 13 moves along the curved section 8a. That is, the movement of the tip of the welding torch 13 that satisfies the above welding conditions in area 2 is a rotational movement at a welding speed Vw around the first curvature center C1 in the YZ plane. In the YZ plane, the position of the tip of the welding torch 13 at time t, with the time when the tip of the welding torch 13 reaches position Pc2 being taken as 0, is the position rotated by an amount of rotation θc (radians) around the first curvature center C1 from position Pc2. However, the amount of rotation θc is expressed by the following formula, using the radius Rc of the curved section 8a and the welding speed Vw. θc = (Vw·t ÷ 2πRc) × 2π Furthermore, at the welding position at time t, the orientation of the welding torch 13 that satisfies the above welding conditions coincides with the direction normal to the curved section 8a. At the welding position at time t, the aiming angle of the welding torch 13 is always constant (θn). At the welding position at time t, the distance between the tip of the welding torch 13 and the curved section 8a is always constant. Matrix U in area 2 is generated as a homogeneous transformation matrix representing the position and orientation of the welding torch 13 as described above.

[0055] In Area 3, the tip of the welding torch 13 moves from position Pc3 to position Pc4 at a welding speed Vw. The movement of the tip of the welding torch 13 in Area 3 is at a welding speed Vw in the Z direction (-Z direction). Therefore, the position of the tip of the welding torch 13 in the Z direction varies with time. Taking the time when the tip of the welding torch 13 reaches position Pc3 as 0, the position of the tip of the welding torch 13 in the Z direction at time t is the position moved by -Vw·t in the Z direction from position Pc3. Note that the position of position Pc3 in the Z direction is equal to the position in the Z direction from the origin position (first curvature center C1) of the steel pipe coordinate system. Also, in Area 3, the position of the tip of the welding torch 13 in the Y direction is always the position moved by +Rc in the Y direction from the origin position (first curvature center C1) of the steel pipe coordinate system. Furthermore, at the welding position at time t, the orientation of the welding torch 13 that satisfies the above welding conditions is perpendicular to the straight section 8b. At the welding position at time t, the aiming angle of the welding torch 13 is always constant (θn). At the welding position at time t, the distance between the tip of the welding torch 13 and the straight section 8b is always constant. Matrix U in Area 3 is generated as a homogeneous transformation matrix representing the position and orientation of the welding torch 13 as described above.

[0056] [Regarding the travel distance of welding robots] The movement of the welding robot 1 will be explained with reference to Figures 3-6. In this embodiment, the welding system 100 has the following movement amounts: Mx of the welding torch 13 in the vertical x direction of the welding robot 1, My of the welding robot 1 in the left-right y direction, Mz of the welding torch 13 in the front-back z direction of the welding robot 1, and M of the welding torch 13 around the first axis. B , and the amount of movement M of the welding torch 13 around the second axis T The control target is the following: That is, the travel amount of the welding robot 1 is travel amount Mx, travel amount My, travel amount Mz, travel amount M B , and displacement M T Includes. Note that the displacement amounts Mx, Mz, and M B , and M T This indicates the amount of movement of the welding torch 13 from its reference position. The reference position of the welding torch 13 is the position and orientation of the welding torch 13 when it is not moving or rotating. The movement amount My indicates the amount of movement of the welding robot 1 relative to a predetermined position on the guide rail 2. The predetermined position is set, for example, to the starting position Pg1 of the curved section 2a of the guide rail 2.

[0057] As shown in Figure 3(a), the amount of movement Mx is controlled by the vertical movement unit 34. That is, the vertical movement unit 34 changes the position of the welding torch 13 in the vertical direction x of the welding robot 1 by moving the first link member 22 relative to the case 21 in the vertical direction x of the welding robot 1. The operation of the vertical movement unit 34 is controlled by driving the motor 32 (servo motor).

[0058] As shown in Figure 4, the amount of movement My is controlled by the motor 32 (servo motor) changing the movement speed of the welding robot 1.

[0059] As shown in Fig. 3(a), the moving amount Mz is controlled by the forward and backward moving part 33. That is, the forward and backward moving part 33 moves the case 21 in the forward and backward direction z of the welding robot 1 with respect to the main body part 11, thereby changing the position of the welding torch 13 in the forward and backward direction z of the welding robot 1. The operation of the forward and backward moving part 33 is controlled by driving a motor 32 (servo motor).

[0060] As shown in Fig. 5(a), the moving amount M B is controlled by the first rotating part 35. That is, the first rotating part 35 rotates the second link member 23 around the first axis with respect to the connection panel 22c, thereby rotating the welding torch 13 around the first axis. The first rotating part 35 changes the orientation of the welding torch 13 around the first axis. The operation of the first rotating part 35 is controlled by driving a motor 32 (servo motor).

[0061] As shown in Fig. 5(b), the moving amount M T is controlled by the second rotating part 36. That is, the second rotating part 36 rotates the third link member 24 around the second axis with respect to the second link member 23, thereby rotating the welding torch 13 around the second axis. The second rotating part 36 changes the orientation of the welding torch 13 around the second axis. The operation of the second rotating part 36 is controlled by driving a motor 32 (servo motor).

[0062] 〔Regarding matrix T〕 Matrix T represents the position and orientation of the welding torch 13 with respect to the origin position (the first curvature center C1) of the steel pipe coordinate system when the moving amount of the welding torch 13 in the vertical direction x of the welding robot 1 is Mx, the moving amount of the welding torch 13 in the forward and backward direction z of the welding robot 1 is Mz, the moving amount of the welding torch 13 around the first axis is M B and the moving amount of the welding torch 13 around the second axis is M T and the moving amount of the welding robot 1 with respect to the reference position Pg1 is My. In the present embodiment, matrix T is a common matrix for areas 1 to 3. In areas 1 to 3, the welding robot 1 moves along the curved section 2a. That is, the movement of the welding robot 1 in areas 1 to 3 is a rotational movement around the second center of curvature C2 in the YZ plane. If the amount of rotation of the welding robot 1 from position Pg1 around the second center of curvature C2 in the YZ plane is θg (in radians), then the amount of movement My can be expressed as the amount of rotation θg as shown in the following equation. Rg is the radius of the curved section 2a. θg = (My ÷ 2πRg) × 2π

[0063] Matrix T consists of matrix T1 for translating the origin position (first curvature center C1) of the steel pipe coordinate system to the position of the second curvature center C2, matrix T2 for representing the position of the welding robot 1 rotated by a rotation amount θg around the second curvature center C2 from position Pg1 (i.e., the position of the welding robot 1 moved by a displacement amount My from position Pg1), and matrix T2 for representing the position of the welding robot 1 after rotation by matrix T2, where the welding robot 1 moves by displacement amounts Mx, Mz, M B , and M T It is obtained by the product of matrix T3, which represents the position and orientation of the tip of the welding torch 13 when moved by only that much, and the result of the product of the matrix T3.

[0064] Matrix T1 is generated by shifting the origin position of the steel pipe coordinate system (first curvature center C1) by -e in the Y and Z directions.

[0065] Matrix T2 is generated by rotating position Pg1 by an amount θg around the second curvature center C2. Position Pg1 is the position moved by +Rg in the Z direction from the second curvature center C2.

[0066] Matrix T3 will be explained with reference to Figure 3(b). Figure 3(b) shows the link structure of the welding robot 1 and the distances between each link when the welding torch 13 is in the reference position. In Figure 3(b), a indicates the distance z in the front-rear direction of the welding robot 1 between the first link pin 351 and the second link pin 361 when the welding torch 13 is in the reference position (see also Figure 5(a)). b indicates the distance x in the vertical direction of the welding robot 1 between the first link pin 351 and the second link pin 361 when the welding torch 13 is in the reference position (see also Figure 5(a)). c indicates the distance x in the vertical direction of the welding robot 1 between the lower end 2c of the guide rail 2 and the first link pin 351 when the welding torch 13 is in the reference position. d indicates the distance z in the front-rear direction of the welding robot 1 between the guide rail 2 and the first link pin 351 when the welding torch 13 is in the reference position. L represents the distance from the second link pin 361 to the tip of the welding torch 13 (see also Figure 5(b)). By using these parameters a to d and L, the position and orientation of the welding torch 13 at the reference position can be expressed. Matrix T3 represents the position and orientation of the welding torch 13 at the reference position, expressed using parameters a~d and L as described above, with displacement amounts Mx, Mz, M B M T This is a homogeneous transformation matrix generated by moving and rotating only a certain amount.

[0067] [Regarding the formula for calculating the travel distance of a welding robot] For the matrices U and T generated as described above, by setting matrix U = matrix T, the travel amounts Mx, My, Mz, and M of the welding robot 1 that satisfy the above welding conditions are obtained. B M T A formula for calculating the value of is derived. This formula is derived when the displacement is Mx, My, Mz, M B M T This formula is derived for each of the following areas. This formula is derived for each of areas 1 to 3.

[0068] [Control system for welding systems] Next, the control system of the welding system 100 will be described with reference to Figures 9 and 10. In the control system, as described above, the amount of movement of the welding robot 1 is determined such that matrix U and matrix T are equal, and the drive of the motor 32 is controlled according to this amount of movement, thereby enabling welding that satisfies the above welding conditions. Figure 9 shows an example of the hardware configuration of the system control device 6 in the embodiment. The system control device 6 includes a processor 91 such as a CPU (Central Processing Unit) and memory 92 connected by a bus, and executes programs. The system control device 6 functions as a device comprising a control unit 61, a communication unit 62, an input unit 63, a storage unit 64, and an output unit 65 through program execution.

[0069] More specifically, the system control device 6 reads the program stored in the storage unit 64 by the processor 91 and stores the read program in the memory 92. By having the processor 91 execute the program stored in the memory 92, the system control device 6 functions as a device comprising a control unit 61, a communication unit 62, an input unit 63, a storage unit 64, and an output unit 65.

[0070] The control unit 61 controls the operation of various functional units of the system control device 6. For example, the control unit 61 controls the operation of the welding robot 1. For example, the control unit 61 causes the welding robot 1 to perform welding. For example, the control unit 61 causes the welding robot 1 to perform welding of the curved section 8a. When controlling the operation of the welding robot 1, for example, the control unit 61 may also control the operation of the welding power supply 4 and the wire feeder 5. Other functions of the control unit 61 will be described later.

[0071] The communication unit 62 is configured to include a communication interface for connecting the system control device 6 to an external device. The communication unit 62 communicates with the external device via wired or wireless means. The external device is, for example, a welding robot 1. The communication unit 62 communicates with the welding robot 1, for example, via a control cable. The communication unit 62 transmits control signals to the welding robot 1, for example. The external device is, for example, an imaging device 3. The communication unit 62 acquires imaging results by communicating with the imaging device 3. The external device is, for example, a welding power supply 4. The external device is, for example, a wire feeding device 5. The communication unit 62 acquires information regarding the position of the welding robot 1 (hereinafter referred to as welding robot position information) via, for example, a control cable. The welding robot position information is, for example, a target value (hereinafter also simply referred to as the target value) for controlling the servo motor (motor 32) related to the movement of the welding robot 1.

[0072] The input unit 63 includes input devices such as a mouse, keyboard, or touch panel. The input unit 63 may also be configured as an interface for connecting these input devices to the system control device 6. The input unit 63 receives various types of information for the system control device 6. For example, the input unit 63 receives an instruction to start welding.

[0073] The storage unit 64 is configured using a computer-readable storage medium device such as a magnetic hard disk drive or a semiconductor storage device. The storage unit 64 stores various information related to the welding system 100, including the system control device 6 itself. The storage unit 64 stores information input via, for example, the communication unit 62 or the input unit 63. The storage unit 64 stores various information generated by, for example, the execution of processing by the control unit 61. The storage unit 64 stores, for example, the imaging results acquired by the imaging device 3.

[0074] The memory unit 64 stores information regarding the shape of each type of steel pipe 8 (hereinafter also referred to as steel pipe shape information) in advance. The steel pipe shape information includes the radius Rc of the curved section 8a, the curvature of the curved section 8a, the position of the first curvature center C1 of the curved section 8a, the length of the straight section 8b, etc. The memory unit 64 also stores information regarding the shape of each type of guide rail 2 (hereinafter also referred to as guide rail shape information) in advance. The guide rail shape information includes the radius Rg of the curved section 2a, the curvature of the curved section 2a, the position of the second curvature center C2 of the curved section 2a, the length of the straight section 2b, etc. The memory unit 64 stores in advance the travel amounts Mx, My, Mz, M for welding robot 1 when matrix U and matrix T are equal, which have been derived for each of areas 1 to 3. B M T Store the formula for calculating it. The memory unit 64 stores the target value (welding robot position information). The memory unit 64 stores the reference position of the welding torch 13. The memory unit 64 stores a predetermined position of the guide rail 2 that serves as the reference for the amount of movement My.

[0075] The output unit 65 outputs various types of information. The output unit 65 is comprised of a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro-Luminescence) display. The output unit 65 may also be configured as an interface for connecting these display devices to the system control device 6. The output unit 65 outputs information input to the input unit 63, for example. The output unit 65 may also display the results of processing performed by the control unit 61, for example.

[0076] Figure 10 shows an example of the functional configuration of the control unit 61 in this embodiment. The control unit 61 comprises a data acquisition unit 610, a welding robot control unit 620, a storage control unit 630, an input control unit 640, and an output control unit 650.

[0077] The data acquisition unit 610 acquires welding robot position information stored in the storage unit 64. The data acquisition unit 610 acquires the movement amounts Mx, My, Mz, M of the welding robot 1 that are previously stored in the storage unit 64. B M T The calculation formula for obtaining the result is obtained. The data acquisition unit 610 acquires the shooting results of the shooting device 3 stored in the storage unit 64. The data acquisition unit 610 acquires steel pipe shape information corresponding to the type of steel pipe 8 used from the storage unit 64. The data acquisition unit 610 also acquires guide rail shape information corresponding to the type of guide rail 2 used from the storage unit 64. The type of steel pipe 8 and the type of guide rail 2 used are entered, for example, by the user into the input unit 63.

[0078] The welding robot control unit 620 controls the operation of the welding robot 1. The welding robot control unit 620 includes a position information acquisition unit 621, a shape information acquisition unit 622 (acquisition unit), a curvature center determination unit 623 (determination unit), a parameter setting unit 624, a welding time count unit 625, an area determination unit 626, a target torch position calculation unit 627, a movement amount setting unit 628, and a curved section welding execution control unit 629. The parameter setting unit 624, the target torch position calculation unit 627, and the movement amount setting unit 628 constitute the setting unit in this embodiment.

[0079] The position information acquisition unit 621 acquires welding robot position information via the storage unit 64 and the data acquisition unit 610.

[0080] The shape information acquisition unit 622 acquires steel pipe shape information and guide rail shape information via the storage unit 64 and the data acquisition unit 610.

[0081] The curvature center determination unit 623 determines whether the position of the first curvature center C1 and the position of the second curvature center C2 coincide, based on the steel pipe shape information and guide rail shape information acquired by the shape information acquisition unit 622. If the positions of the first curvature center C1 and the second curvature center C2 do not coincide, the curvature center determination unit 623 determines which of the first curvature center C1 and the second curvature center C2 is located towards the center of the steel pipe 8.

[0082] The parameter setting unit 624 acquires the imaging results from the imaging device 3 via the storage unit 64 and the data acquisition unit 610. Based on the imaging results from the imaging device 3 and the steel pipe shape information and guide rail shape information acquired by the shape information acquisition unit 622, the parameter setting unit 624 determines the shape and condition of the welded area (for example, groove information). The parameter setting unit 624 sets specific values ​​for the welding conditions, including the welding movement speed Vw of the welding torch 13, the welding torch direction, the target angle θn, and the target position, based on the shape and condition of the identified welding area.

[0083] The welding time counting unit 625 counts the elapsed time t from the start of welding of the curved section 8a (i.e., when the welding robot 1 reaches position Pg1 in area 1).

[0084] The area determination unit 626 obtains the welding movement speed Vw set by the parameter setting unit 624. The area determination unit 626 obtains the elapsed time t from the welding time count unit 625. The area determination unit 626 calculates the target position of the tip of the welding torch 13 at the obtained elapsed time t. Specifically, since the tip of the welding torch 13 moves along the steel pipe 8 at the welding movement speed Vw, the position of the tip of the welding torch 13 at time t is the position obtained by moving Vw·t along the steel pipe 8 from position Pc1. The area determination unit 626 determines which of areas 1 to 3 the calculated target position of the tip of the welding torch 13 is located in.

[0085] The target torch position calculation unit 627, via the storage unit 64 and the data acquisition unit 610, calculates the movement amount Mx, My, Mz, M of the welding robot 1. B M T The calculation formula for determining the target torch position is obtained. The target torch position calculation unit 627 obtains the specific values ​​of the welding movement speed Vw, welding torch direction, target angle θn, and target position of the welding torch 13 set by the parameter setting unit 624. The target torch position calculation unit 627 reflects the specific values ​​of the welding movement speed Vw, welding torch direction, target angle θn, and target position of the welding torch 13 set by the parameter setting unit 624 into the above calculation formula.

[0086] The movement amount setting unit 628 sets the movement amount Mx, My, Mz, M of the welding robot 1 at a predetermined time t based on the calculation formula acquired by the target torch position calculation unit 627. B M T These values ​​are calculated and set as the travel distances for welding robot 1. In other words, the movement amount setting unit 628, based on matrices U and T, sets the movement amounts Mx, My, Mz, M of the welding robot 1 that satisfy the welding movement speed Vw, welding torch direction, target angle θn, and target position of the welding torch 13 under the above welding conditions. B M T Set it.

[0087] The curved section welding execution control unit 629 controls the movement amounts Mx, My, Mz, M set by the movement amount setting unit 628. B M T The position of the welding robot 1 and the position and orientation of the welding torch 13 are changed accordingly, and the welding robot 1 is made to perform welding of the curved section 8a. Specifically, the curved section welding execution control unit 629 drives the motor 32 to operate the vertical movement unit 34, and changes the position of the welding torch 13 in the vertical x direction of the welding robot 1 according to the movement amount Mx set by the movement amount setting unit 628. The curved section welding execution control unit 629 drives the motor 32 to operate the forward / backward movement unit 33, and changes the position of the welding torch 13 in the forward / backward z direction of the welding robot 1 according to the movement amount Mz set by the movement amount setting unit 628. The curved section welding execution control unit 629 drives the motor 32 to operate the first rotation unit 35, and changes the position of the welding torch 13 in the forward / backward z direction of the welding robot 1 according to the movement amount Mz set by the movement amount setting unit 628. B The orientation of the welding torch 13 around the first axis is changed accordingly. The curved section welding execution control unit 629 drives the motor 32 to operate the second rotation unit 36, and the movement amount M set by the movement amount setting unit 628 is changed. T The orientation of the welding torch 13 around the second axis is changed accordingly. The curved section welding execution control unit 629 drives the motor 32 (servo motor) to change the position of the welding robot 1 according to the amount of movement My set by the movement amount setting unit 628.

[0088] The memory control unit 630 records various information in the storage unit 64. The memory control unit 630 records various information generated by the operation of the control unit 61, for example, in the storage unit 64. The information generated by the operation of the control unit 61 is, for example, information indicating the content of the control of the welding robot 1 by the welding robot control unit 620.

[0089] The input control unit 640 controls the operation of the input unit 63. The output control unit 650 controls the operation of the output unit 65.

[0090] [Example of control performed by a welding system] Referring to Figure 11, an example of the control performed by the welding system 100 will be described. Figure 11 is a flowchart showing an example of the welding process flow of the curved section 8a executed by the system control device 6 in this embodiment.

[0091] Before welding the curved section 8a, the curvature center determination unit 623 determines whether the position of the first curvature center C1 coincides with the position of the second curvature center C2. If the positions of the first curvature center C1 and the second curvature center C2 do not coincide, the curvature center determination unit 623 determines which of the first curvature center C1 or the second curvature center C2 is located closer to the center of the steel pipe 8. In this embodiment, the welding process for the curved section 8a will be described below when the curvature center determination unit 623 determines that the second curvature center C2 is located closer to the center of the steel pipe 8 than the first curvature center C1.

[0092] The welding process for the curved section 8a begins when the welding robot 1 reaches position Pg1. At this time, the tip of the welding torch 13 is located at position Pc1 in area 1. For example, the determination of whether or not to start the welding process for the curved section 8a is performed by estimating the position of the welding robot 1 based on the welding robot position information acquired by the position information acquisition unit 622, and determining whether or not the estimated position of the welding robot 1 has reached position Pg1.

[0093] When the welding process of the curved section 8a begins, the welding time counting unit 625 starts counting the elapsed time t from the start of the welding process of the curved section 8a (step S101). The area determination unit 626 calculates the target position of the tip of the welding torch 13 at the elapsed time t (step S102). The area determination unit 626 determines which of areas 1 to 3 the calculated target position of the tip of the welding torch 13 is located in (step S103).

[0094] If it is determined that the tip of the welding torch 13 is located in area 1 (step S103:A1), the movement amount setting unit 628 sets the movement amount Mx, My, Mz, M for the welding robot 1 corresponding to area 1. B M T The calculation formula for obtaining the above formula is obtained. Based on the above formula, the movement amount setting unit 628 calculates the amount of rotation θg from the position Pg1 of the welding robot 1 on the curved section 2a of the guide rail 2 at the elapsed time t (step S111). Also, based on the above formula, the movement amount setting unit 628 calculates the amount of movement Mx, My, Mz, M of the welding robot 1 at the elapsed time t. B M T The value is calculated and set as the travel amount for welding robot 1 (step S112). The process then proceeds to step S105.

[0095] If it is determined that the tip of the welding torch 13 is located in area 2 (step S103:A2), the movement amount setting unit 628 sets the movement amount Mx, My, Mz, M for the welding robot 1 corresponding to area 2. B M T The calculation formula for obtaining the following is obtained. Here, in area 2, the movement of the tip of the welding torch 13 is a rotational movement around the first curvature center C1, so the target torch position calculation unit 627 calculates the target position of the tip of the welding torch 13 calculated in step S102 as the amount of rotation θc of the tip of the welding torch 13 in the curved section 8a of the steel pipe 8 (step S121). Based on the above calculation formula, the movement amount setting unit 628 calculates the amount of rotation θg from the position Pg1 of the welding robot 1 in the curved section 2a of the guide rail 2 at elapsed time t (step S122). Also, based on the above calculation formula, the movement amount setting unit 628 calculates the amount of movement Mx, My, Mz, M of the welding robot 1 at elapsed time t. B M T The value is calculated and set as the travel amount for welding robot 1 (step S123). The process then proceeds to step S105.

[0096] If it is determined that the tip of the welding torch 13 is located in area 3 (step S103:A3), the movement amount setting unit 628 sets the movement amounts Mx, My, Mz, M for the welding robot 1 corresponding to area 3. B M T The calculation formula for obtaining the above formula is obtained. Based on the above formula, the movement amount setting unit 628 calculates the amount of rotation θg from the position Pg1 of the welding robot 1 on the curved section 2a of the guide rail 2 at the elapsed time t (step S131). Also, based on the above formula, the movement amount setting unit 628 calculates the amount of movement Mx, My, Mz, M of the welding robot 1 at the elapsed time t. B M T The value is calculated and set as the travel amount for welding robot 1 (step S132). The process then proceeds to step S105.

[0097] The curved section welding execution control unit 629 drives each motor 32 to execute the movement amounts Mx, My, Mz, M set by the movement amount setting unit 628. B M T The position of the welding robot 1 and the position and orientation of the welding torch 13 are changed accordingly, and the welding robot 1 is made to perform welding of the curved section 8a (step S105).

[0098] Subsequently, the area determination unit 626 determines whether the tip of the welding torch 13 has reached the end position Pc4 of area 3 (step S106). If it is determined that the tip of the welding torch 13 has reached position Pc4 (step S106: YES), the curved section welding execution control unit 629 terminates the welding process of the curved section 8a (step S206). On the other hand, if the tip of the welding torch 13 has not reached position Pc4 (step S106: NO), the process returns to step S102. In this case, the welding process of the curved section 8a continues.

[0099] The following describes the specific control details of the welding robot 1 in each area when the above control is performed. Note that the control details of the welding robot 1 shown below are just an example, and the present invention is not limited thereto.

[0100] First, the control details in Area 4 (i.e., the area of ​​the curved section 8a other than the welding area) will be explained. In Area 4, the welding robot 1 moves at a constant speed (welding movement speed Vw). Hereafter, the movement speed of the welding robot 1 in Area 4 will also be referred to as the reference speed. Also, the amount of movement Mx of the welding torch 13 in the vertical direction x is constant (hereinafter also referred to as the vertical movement reference value). The amount of movement Mz of the welding torch 13 in the forward / backward direction z is constant (hereinafter also referred to as the forward / backward movement reference value). The amount of movement M of the welding torch 13 around the first axis B The first axis rotation reference value is constant (hereinafter also referred to as the first axis rotation reference value), and the welding torch 13 is rotated vertically downward around the first axis. The amount of movement M of the welding torch 13 around the second axis T This is constant and is 0 (zero). That is, when viewed along the vertical direction x, the welding torch 13 is always perpendicular to the left-right direction y (i.e., the straight section 8b of the steel pipe 8), which is the direction of travel of the welding robot 1. In the following explanation, the amount of movement Mx is assumed to increase when the welding torch 13 moves downward and decrease when it moves upward. The amount of movement Mz is assumed to increase when the welding torch 13 moves backward (i.e., away from the steel pipe 8) and decrease when it moves forward (i.e., closer to the steel pipe 8). Amount of movement M B It is said that this increases when the vertical downward inclination of the welding torch 13 increases. Displacement M T This value is defined as 0 when the welding torch 13 is perpendicular to the direction of travel of the welding robot 1, increases when the welding torch 13 is tilted toward the direction of travel of the welding robot 1, and decreases when it is tilted toward the opposite direction of travel of the welding robot 1, when viewed along the vertical direction x.

[0101] The control details in Area 1 will be explained. In Area 1, the movement speed of welding robot 1 becomes lower than the reference speed. That is, welding robot 1 instantaneously decelerates to the movement speed in Area 1. "Instantaneously" refers to the moment it arrives in Area 1 from Area 4. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz increases from the reference value for forward and backward movement as the tip of the welding torch 13 moves from position Pc1 to position Pc2. In other words, as the tip of the welding torch 13 moves from position Pc1 to position Pc2, it moves away from the steel pipe 8. Travel amount M B As the tip of the welding torch 13 moves from position Pc1 to position Pc2, the first axis rotation reference value increases. In other words, as the tip of the welding torch 13 moves from position Pc1 to position Pc2, the downward vertical inclination of the welding torch 13 increases. Travel amount M T This value increases from 0 as the tip of the welding torch 13 moves from position Pc1 to position Pc2. In other words, when viewed along the vertical direction x, as the tip of the welding torch 13 moves from position Pc1 to position Pc2, the welding torch 13 tilts toward the direction of travel of the welding robot 1.

[0102] The control details for Area 2 will be explained below. In Area 2, the welding robot 1's movement speed is greater than the reference speed. That is, the welding robot 1 instantaneously accelerates to its movement speed in Area 2. Instantaneously means the moment it arrives in Area 2 from Area 1. Also, in the range from position Pc2 to the midpoint between position Pc2 and position Pc3, the welding robot 1 continues to decelerate with a predetermined negative acceleration from the starting position Pc2 in Area 2 to the aforementioned midpoint. Even in this case, the welding robot 1's movement speed is greater than the reference speed. Subsequently, in the range from the midpoint between position Pc2 and position Pc3 to position Pc3, the welding robot 1 continues to accelerate with a predetermined positive acceleration from the aforementioned midpoint to the end position Pc3 in Area 2. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz increases as the tip of the welding torch 13 moves from position Pc2 to an intermediate position between position Pc2 and position Pc3, and decreases as the tip of the welding torch 13 moves from the intermediate position between position Pc2 and position Pc3 to position Pc3. In other words, the welding torch 13 moves away from the steel pipe 8 in the range from position Pc2 to the intermediate position between position Pc2 and position Pc3, and moves towards the steel pipe 8 in the range from the intermediate position between position Pc2 and position Pc3 to position Pc3. Travel amount M B The amount of movement M decreases as the tip of the welding torch 13 moves from position Pc2 to an intermediate position between position Pc2 and position Pc3, and increases as the tip of the welding torch 13 moves from the intermediate position between position Pc2 and position Pc3 to position Pc3. Even in this case, the amount of movement M B The first axis rotation reference value will never be smaller. That is, as the tip of the welding torch 13 moves from position Pc2 to an intermediate position between position Pc2 and position Pc3, the downward vertical inclination of the welding torch 13 decreases, and as the tip of the welding torch 13 moves from an intermediate position between position Pc2 and position Pc3 to position Pc3, the downward vertical inclination of the welding torch 13 increases. Travel amount M T The amount of movement M decreases as the tip of the welding torch 13 moves from position Pc2 to position Pc3. T This value becomes 0 when the tip of the welding torch 13 is located at the midpoint between position Pc2 and position Pc3. That is, when viewed along the vertical x direction, when the tip of the welding torch 13 is located at position Pc2, which is the end position of area 1, the welding torch 13 is tilted toward the direction of travel of the welding robot 1. As the tip of the welding torch 13 moves from position Pc2 to the midpoint between position Pc2 and position Pc3, the tilt of the welding torch 13 toward the direction of travel of the welding robot 1 decreases, and when the tip of the welding torch 13 reaches the midpoint between position Pc2 and position Pc3, the welding torch 13 is perpendicular to the direction of travel of the welding robot 1. Subsequently, as the tip of the welding torch 13 moves from the midpoint between position Pc2 and position Pc3 to position Pc3, the welding torch 13 tilts toward the opposite side of the direction of travel of the welding robot 1.

[0103] The control details in Area 3 will be explained. In Area 3, the movement speed of welding robot 1 becomes lower than the reference speed. In other words, welding robot 1 instantaneously decelerates to the movement speed in Area 3. This instantaneous deceleration occurs at the moment it moves from Area 2 to Area 3. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz decreases as the tip of the welding torch 13 moves from position Pc3 to position Pc4, and becomes equal to the reference value of forward / backward movement when the tip of the welding torch 13 reaches position Pc4. In other words, as the tip of the welding torch 13 moves from position Pc3 to position Pc4, it moves in a direction that approaches the steel pipe 8. Travel amount M B This value decreases as the tip of the welding torch 13 moves from position Pc3 to position Pc4, and becomes equal to the reference value of the first axis rotation when the tip of the welding torch 13 reaches position Pc4. In other words, as the tip of the welding torch 13 moves from position Pc3 to position Pc4, the downward vertical inclination of the welding torch 13 decreases. Travel amount M T The angle increases as the tip of the welding torch 13 moves from position Pc3 to position Pc4, and becomes 0 when the tip of the welding torch 13 reaches position Pc4. That is, when viewed along the vertical direction x, the tip of the welding torch 13 is at position Pc3, which is the end position of area 2, and the welding torch 13 is tilted in the opposite direction to the direction of travel of the welding robot 1. As the tip of the welding torch 13 moves from position Pc3 to position Pc4, the tilt of the welding torch 13 in the opposite direction to the direction of travel of the welding robot 1 decreases, and when the tip of the welding torch 13 reaches position Pc4, the welding torch 13 is perpendicular to the direction of travel of the welding robot 1.

[0104] The welding system 100 according to this embodiment controls a welding robot 1 that moves along a guide rail 2 arranged along a steel pipe 8 and has a curved section 2a, and welds the curved section 8a of the steel pipe 8. The welding system 100 includes a shape information acquisition unit 622 that acquires a first curvature center C1 of the curved section 8a, and a setting unit that sets the welding conditions of the welding robot 1 using the first curvature center C1 acquired by the shape information acquisition unit 622.

[0105] Even if the centers of curvature of the curved section 8a of the steel pipe 8 and the curved section 2a of the guide rail 2 are different, the welding conditions are set using the first center of curvature C1 of the curved section 8a of the steel pipe 8 that is to be welded. Therefore, the welding of the curved section 8a can be performed well regardless of the variation in distance between the steel pipe 8 and the guide rail 2. Thus, good welding quality can be obtained.

[0106] Furthermore, the welding system 100 includes a curvature center determination unit 623 that determines whether the first curvature center C1 and the second curvature center C2 coincide. The setting unit sets the welding conditions using the first curvature center C1 when the curvature center determination unit 623 determines that the first curvature center C1 and the second curvature center C2 do not coincide. When the curvature center determination unit 623 determines that the first curvature center C1 and the second curvature center C2 do not coincide, the welding conditions are set using the first curvature center C1, thereby simplifying the control of the welding system 100.

[0107] Furthermore, the welding conditions include the welding torch orientation, which is the direction of the welding torch 13 relative to the curved portion 8a of the steel pipe 8. The welding system 100 includes a first rotating part 35 and a second rotating part 36 for changing the orientation of the welding torch 13. The setting unit sets the orientation of the welding torch using a first curvature center C1 and a second curvature center C2. The first rotating part 35 and the second rotating part 36 change the orientation of the welding torch 13 so that the orientation of the welding torch 13 with respect to the curved portion 8a of the steel pipe 8 matches the welding torch orientation set by the setting unit. The welding torch orientation includes the orientation of the welding torch 13 when, in a top view, the direction of the tip of the welding torch 13 coincides with the normal direction of the curved portion 8a of the steel pipe 8, and the setting unit sets the welding torch orientation according to the position of the welding robot 1. This allows the welding torch 13 to always be oriented perpendicular to the steel pipe 8, thereby improving welding quality.

[0108] Furthermore, one of the first rotating part 35 and the second rotating part 36 rotates the other together with the welding torch 13. The welding torch orientation includes the orientation of the welding torch 13 when the tip of the welding torch 13 is positioned in the groove of the steel pipe 8, as viewed along the direction in which the welding robot 1 moves, and the setting unit sets the welding torch orientation according to the rotation by this one. This improves welding quality because, when viewed along the direction in which the welding robot 1 moves, the orientation of the welding torch 13 when the tip of the welding torch 13 is positioned at the groove of the steel pipe 8 can be kept constant (i.e., the aiming angle θn of the welding torch 13). For example, the aiming angle θn can be kept constant by setting the angle of the first rotating part 35 according to the angle of the second rotating part 36. More specifically, as the smaller of the two angles formed by the front-rear direction z and the welding torch 13 increases due to the rotation of the second rotating part 36, the smaller of the two angles formed by the up-down direction x and the welding torch 13 decreases due to the rotation of the first rotating part 35.

[0109] Furthermore, the welding conditions include the welding travel speed Vw, which is the travel speed of the tip of the welding torch 13. The welding system 100 includes a motor 32 (servo motor) that changes the position (movement speed) of the welding robot 1. The setting unit sets the welding movement speed Vw using a first curvature center C1 and a second curvature center C2. The motor 32 (servo motor) changes the position (movement speed) of the welding robot 1 so that the movement speed of the tip of the welding torch 13 matches the welding movement speed Vw set in the setting unit. This allows the position (movement speed) of the welding robot 1 to be controlled so that the tip of the welding torch 13 moves along the welding area of ​​the steel pipe 8 at a predetermined speed (welding movement speed Vw), thereby improving welding quality.

[0110] Furthermore, the welding conditions include the target position of the welding torch 13. The welding system 100 includes a forward / backward movement unit 33 and an up / down movement unit 34 for changing the position of the welding torch 13. The setting unit sets the target position using a first curvature center C1 and a second curvature center C2. The forward / backward movement unit 33 and the up / down movement unit 34 change the position of the welding torch 13 so that the position of the welding torch 13 matches the target position set by the setting unit. This allows the position of the welding torch 13 to be controlled so that the distance between the tip of the welding torch 13 and the welding area of ​​the steel pipe 8 is a predetermined length, thereby improving welding quality.

[0111] [Second Embodiment] Hereinafter, a welding system 100 according to a second embodiment of the present invention will be described with reference to Figures 12 and 13. In this embodiment, a control method for the welding system 100 will be described when the first curvature center C1 is located closer to the center of the steel pipe 8 than the second curvature center C2. The basic configuration and operation of the welding system 100 used in this embodiment are the same as those of the welding system 100 in the first embodiment.

[0112] [Curved section of steel pipe and curved section of guide rail] Referring to Figure 12, the curved section 8a of the steel pipe 8 and the curved section 2a of the guide rail 2 will be described. As shown in Figure 12, in this embodiment, the first center of curvature C1 is located closer to the center of the steel pipe 8 than the second center of curvature C2. The second center of curvature C2 is located at a position e away from the first center of curvature C1 in both the Y and Z directions.

[0113] In this embodiment, the welding of the steel pipe 8 is divided into area 5, area 6, area 7, and area 8, depending on the welding method. In the following, the starting position of curved section 8a will be Pc5 and its ending position will be Pc6. The starting position of curved section 2a will be Pg6 and its ending position will be Pg7. Position Pg5 is the intersection of the straight line connecting the first center of curvature C1 and position Pc5 with the straight section 2b of the guide rail 2. Position Pg8 is the intersection of the straight line connecting the first center of curvature C1 and position Pc6 with the straight section 2b of the guide rail 2.

[0114] Area 5 is the area where the welding robot 1 moves from position Pg5 to position Pg6 of the guide rail 2. In Area 5, the welding robot 1 moves along the straight section 2b of the guide rail 2 while welding the curved section 8a of the steel pipe 8. In other words, in Area 5, the welding robot 1 is positioned on the straight section 2b of the guide rail 2, and the part that the welding robot 1 is welding is the curved section 8a of the steel pipe 8. Area 6 is the area in which the welding robot 1 moves from position Pg6 to position Pg7 of the guide rail 2. In Area 6, the welding robot 1 moves along the curved section 2a of the guide rail 2 and welds the curved section 8a of the steel pipe 8. In other words, in Area 6, the welding robot 1 is positioned on the curved section 2a of the guide rail 2, and the part that the welding robot 1 welds is the curved section 8a of the steel pipe 8. Area 7 is the area where the welding robot 1 moves from position Pg7 to position Pg8 of the guide rail 2. In Area 7, the welding robot 1 moves along the straight section 2b of the guide rail 2 while welding the curved section 8a of the steel pipe 8. In other words, in Area 7, the welding robot 1 is positioned on the straight section 2b of the guide rail 2, and the part that the welding robot 1 is welding is the curved section 8a of the steel pipe 8. Area 8 is the area of ​​the steel pipe 8 other than areas 5 to 7. In area 8, the welding robot 1 moves along the straight section 2b of the guide rail 2 and welds the straight section 8b of the steel pipe 8. In other words, in area 8, the welding robot 1 is positioned on the straight section 2b of the guide rail 2, and the part that the welding robot 1 welds is the straight section 8b of the steel pipe 8. In this embodiment, welding of the curved section 8a refers to welding of areas 5 to 7.

[0115] [Welding conditions] Similar to the first embodiment, in order to ensure good welding quality, the following applies regardless of the area: <1> ~ <4> It is preferable to satisfy the welding conditions shown. <1> The speed at which the tip of the welding torch 13 moves along the welding area of ​​the steel pipe 8 (hereinafter also referred to as the welding movement speed Vw) becomes constant. <2> The orientation of the welding torch 13 in a top view (hereinafter also referred to as the welding torch orientation) coincides with the normal direction of the curved portion 8a of the steel pipe 8, or is perpendicular to the straight portion 8b of the steel pipe 8. <3> The aiming angle θn of the welding torch 13 remains constant. <4> The distance between the tip of the welding torch 13 and the welding area of ​​the steel pipe 8 (hereinafter also referred to as the target position of the welding torch 13) is constant.

[0116] In area 8, the distance between the steel pipe 8 (straight section 8b) and the guide rail 2 (straight section 2b) is constant. Therefore, the amount of movement of the welding robot 1 that satisfies the above welding conditions is uniformly determined.

[0117] On the other hand, in areas 5 to 7, the distance between the steel pipe 8 and the guide rail 2 differs depending on the circumferential position, so the amount of movement of the welding robot 1 that satisfies the above welding conditions cannot be uniformly determined. Therefore, in this embodiment as well, similar to the first embodiment, inverse kinematics is used for welding in areas 5 to 7 (welding of the curved section 8a), The target position and target orientation of the welding torch 13 that satisfy the above welding conditions are calculated. We will determine the amount of movement required for welding robot 1 to achieve this. Specifically, the matrix U (as described above) represents the target position and target orientation of the welding torch 13 that satisfies the above welding conditions. It generates a matrix T (corresponding to the above) that represents the position and orientation of the welding torch 13 when the welding robot 1 moves by a predetermined amount. This generates a matrix (corresponding to the above). The amount of movement of the welding robot 1 such that matrix U and matrix T are equal is determined, and by controlling the drive of the motor 32 according to the amount of movement, welding that satisfies the above welding conditions can be performed.

[0118] [Regarding matrix U] Matrix U is a matrix used to represent the target position and target orientation of the welding torch 13 that satisfies the above welding conditions, with reference to the origin position (first curvature center C1) of the steel pipe coordinate system. In this embodiment, welding of the curved section 8a is performed in all of areas 5 to 7. Therefore, a common matrix U is generated for areas 5 to 7.

[0119] In areas 5 to 7, the tip of the welding torch 13 moves along the curved section 8a. That is, the movement of the tip of the welding torch 13 that satisfies the above welding conditions in areas 5 to 7 is a rotational movement at a welding speed Vw around the first curvature center C1 in the YZ plane. In the YZ plane, the position of the tip of the welding torch 13 at time t, with the time when the tip of the welding torch 13 reaches position Pc5 being taken as 0, is the position rotated by an amount of rotation θc (radians) around the first curvature center C1 from position Pc5. However, the amount of rotation θc is expressed by the following formula, using the radius Rc of the curved section 8a and the welding speed Vw. θc = (Vw·t ÷ 2πRc) × 2π Furthermore, at the welding position at time t, the orientation of the welding torch 13 that satisfies the above welding conditions coincides with the direction normal to the curved section 8a. At the welding position at time t, the aiming angle of the welding torch 13 is always constant (θn). At the welding position at time t, the distance between the tip of the welding torch 13 and the curved section 8a is always constant. Matrix U is generated as a homogeneous transformation matrix representing the position and orientation of the welding torch 13 as described above.

[0120] [Regarding matrix T] Matrix T represents the amount of movement of the welding torch 13 in the vertical x direction of the welding robot 1, Mx, the amount of movement of the welding torch 13 in the forward / backward z direction of the welding robot 1, and M B The amount of movement of the welding torch 13 around the second axis is M T This matrix represents the position and orientation of the welding torch 13 relative to the origin of the steel pipe coordinate system (first curvature center C1), given that the amount of movement of the welding robot 1 relative to position Pg1 is My. In this embodiment, the welding robot 1 moves along the straight section 2b in areas 5 and 7, and moves along the curved section 2a in area 6. Therefore, matrix T is generated for each of areas 5 to 7.

[0121] The generation of matrix T in area 5 will be explained. Matrix T in area 5 is a matrix T4 that represents the position of welding robot 1 after moving it by a displacement amount My from position Pg5, and at the position of welding robot 1 after movement by matrix T4, welding robot 1 is moved by displacement amounts Mx, Mz, M B , and M T It is obtained by the product of matrix T3, which represents the position and orientation of the tip of the welding torch 13 when moved by only that much, and the result of the product of the matrix T3. In area 5, the welding robot 1 moves along the straight section 2b in the Y direction (+Y direction). Therefore, matrix T4 is generated by moving position Pg5 by +My in the Y direction. Note that position Pg5 is the position moved by +Rg in the Z direction from the first curvature center C1. Note that matrix T3 is the same as matrix T3 in the first embodiment, so its description is omitted here.

[0122] The generation of matrix T in area 6 will be explained. Matrix T in area 6 consists of matrix T1 for translating the origin position of the steel pipe coordinate system (first curvature center C1) to the position of the second curvature center C2, matrix T5 for representing the position of welding robot 1 rotated by a rotation amount θg around the second curvature center C2 from position Pg6 (i.e., the position of welding robot 1 moved by a displacement amount My from position Pg6), and matrix T5 for representing the position of welding robot 1 after rotation by matrix T5, ​​where welding robot 1 moves by displacement amounts Mx, Mz, M B , and M T It is obtained by the product of matrix T3, which represents the position and orientation of the tip of the welding torch 13 when moved by only that much, and the result of the product of the matrix T3. In area 6, the welding robot 1 moves along the curved section 2a. That is, the movement of the welding robot 1 in area 6 is a rotational movement around the second center of curvature C2 in the YZ plane. If the amount of rotation of the welding robot 1 from position Pg6 around the second center of curvature C2 in the YZ plane is θg (in radians), then the amount of movement My can be expressed as the amount of rotation θg as shown in the following equation. Note that Rg is the radius of the curved section 2a. θg = (My ÷ 2πRg) × 2π Matrix T2 is generated by rotating position Pg6 by an amount θg around the second curvature center C2. Note that position Pg6 is the position moved by +Rg in the Z direction from the second curvature center C2. Note that matrices T1 and T3 are the same as those in the first embodiment, so their description is omitted here.

[0123] The generation of matrix T in area 7 will be explained. Matrix T in area 7 is a matrix T6 that represents the position of welding robot 1 after moving by a displacement amount My from position Pg7, and at the position of welding robot 1 after movement by matrix T6, welding robot 1 is moved by displacement amounts Mx, Mz, M B , and M T It is obtained by the product of matrix T3, which represents the position and orientation of the tip of the welding torch 13 when moved by only that much, and the result of the product of the matrix T3. In area 7, the welding robot 1 moves along the straight section 2b in the Z direction (-Z direction). Therefore, matrix T6 is generated by moving position Pg7 by -My in the Z direction. Position Pg7 is the position obtained by moving +Rg in the Y direction and +e in the Z direction from the first curvature center C1. Note that matrix T3 is the same as matrix T3 in the first embodiment, so its description is omitted here.

[0124] [Regarding the formula for calculating the travel distance of a welding robot] For the matrices U and T generated as described above, by setting matrix U = matrix T, the travel amounts Mx, My, Mz, and M of the welding robot 1 that satisfy the above welding conditions are obtained. B M T A formula for calculating the value of is derived. This formula is derived when the displacement is Mx, My, Mz, M B M T This formula is derived for each of the following areas. This formula is derived for each of areas 5 through 7.

[0125] [Control system for welding systems] The basic structure and operation of the control system of the welding system 100 in this embodiment are the same as those of the control system in the first embodiment. On the other hand, in this embodiment, matrix U is generated as a matrix common to areas 5 to 7. Matrix T is generated for each of areas 5 to 7. The memory unit 64 stores in advance the travel amounts Mx, My, Mz, M for welding robot 1 when matrix U and matrix T are equal, which have been derived for each of areas 5 to 7. B M T The calculation formula for determining the target torch position is stored. The target torch position calculation unit 627 acquires the above calculation formula via the storage unit 64 and the data acquisition unit 610. Based on the above calculation formula, the movement amount setting unit 628 sets the movement amount Mx, My, Mz, M of the welding robot 1 at a predetermined time t. B M T These values ​​are calculated and set as the travel distances for welding robot 1. Furthermore, the configuration and operation of the control system other than those described above are the same as those of the control system in the first embodiment, and therefore will not be described.

[0126] [Example of control performed by a welding system] Referring to Figure 13, an example of the control performed by the welding system 100 will be described. Figure 13 is a flowchart showing an example of the welding process flow of the curved section 8a executed by the system control device 6 in this embodiment.

[0127] Before welding the curved section 8a, the curvature center determination unit 623 determines whether the position of the first curvature center C1 coincides with the position of the second curvature center C2. If the positions of the first curvature center C1 and the second curvature center C2 do not coincide, the curvature center determination unit 623 determines which of the first curvature center C1 or the second curvature center C2 is located closer to the center of the steel pipe 8. In this embodiment, the welding process for the curved section 8a will be described below when the curvature center determination unit 623 determines that the first curvature center C1 is located closer to the center of the steel pipe 8 than the second curvature center C2.

[0128] The welding process for the curved section 8a begins when the welding robot 1 reaches position Pg5. At this time, the tip of the welding torch 13 is located at position Pc5 in area 5. For example, the determination of whether or not to start the welding process for the curved section 8a is performed by estimating the position of the welding robot 1 based on the welding robot position information acquired by the position information acquisition unit 622, and determining whether or not the estimated position of the welding robot 1 has reached position Pg5.

[0129] When the welding process of the curved section 8a begins, the welding time counting unit 625 starts counting the elapsed time t from the start of the welding process of the curved section 8a (step S201). The area determination unit 626 calculates the target position of the tip of the welding torch 13 at the elapsed time t (step S202). In this embodiment, since the movement of the tip of the welding torch 13 is a rotational movement around the first curvature center C1 in all areas 5 to 7, the target torch position calculation unit 627 calculates the target position of the tip of the welding torch 13 calculated in step S202 as the amount of rotation θc of the tip of the welding torch 13 in the curved section 8a of the steel pipe 8 (step S203).

[0130] The area determination unit 626 determines which of areas 5 to 7 the calculated target position of the tip of the welding torch 13 is located in (step S204).

[0131] If it is determined that the tip of the welding torch 13 is located in area 5 (step S204:A5), the movement amount setting unit 628 sets the movement amounts Mx, My, Mz, M for the welding robot 1 corresponding to area 5. B M T The calculation formula is obtained to determine the amount of movement Mx, My, Mz, M of the welding robot 1 at elapsed time t. Based on the above calculation formula, the movement amount setting unit 628 determines the amount of movement Mx, My, Mz, M of the welding robot 1 at elapsed time t. B M T The value is calculated and set as the travel amount for welding robot 1 (step S211). The process then proceeds to step S205.

[0132] If it is determined that the tip of the welding torch 13 is located in area 6 (step S204:A6), the movement amount setting unit 628 sets the movement amounts Mx, My, Mz, M for the welding robot 1 corresponding to area 6. B M T The calculation formula is obtained to determine the following. In area 6, since the movement of the welding robot 1 is a rotational movement around the second curvature center C2, the movement amount setting unit 628 first calculates the amount of rotation θg from the position Pg6 of the welding robot 1 on the curved section 2a of the guide rail 2 at elapsed time t, based on the above calculation formula (step S221). The movement amount setting unit 628 also calculates the amount of movement Mx, My, Mz, M of the welding robot 1 at elapsed time t based on the above calculation formula. B M T Calculate it and set it as the movement amount of the welding robot 1 (step S222). Then, the process proceeds to step S205.

[0133] When it is determined that the tip of the welding torch 13 is located in area 7 (step S204: A7), the movement amount setting unit 628 obtains the calculation formula for obtaining the movement amounts Mx, My, Mz, M of the welding robot 1 corresponding to area 7. B , M T Based on the above calculation formula, the movement amount setting unit 628 calculates the movement amounts Mx, My, Mz, M of the welding robot 1 at the elapsed time t, B , M T and sets them as the movement amounts of the welding robot 1 (step S231). Then, the process proceeds to step S205.

[0134] The curved portion welding execution control unit 629 drives each motor 32 to change the position of the welding robot 1, the position and posture of the welding torch 13 according to the set movement amounts Mx, My, Mz, M, B , M T and causes the welding robot 1 to perform welding on the curved portion 8a (step S205).

[0135] Thereafter, the area determination unit 626 determines whether or not the position of the tip of the welding torch 13 has reached the end position Pc6 of area 7 (step S206). When it is determined that the position of the tip of the welding torch 13 has reached the position Pc6 (step S206: YES), the curved portion welding execution control unit 629 ends the welding process of the curved portion 8a. On the other hand, when the position of the tip of the welding torch 13 has not reached the position Pc6 (step S206: NO), the process returns to the process of step S202. In this case, the welding process of the curved portion 8a is continued.

[0136] Hereinafter, the specific control content of the welding robot 1 in each area when the above control is performed will be described. Note that the control content of the welding robot 1 shown below is an example, and the present invention is not limited thereto.

[0137] First, the control details in area 8 (i.e., the area of ​​the curved section 8a other than the welding area) will be explained. In area 8, the welding robot 1 moves at a constant speed (welding movement speed Vw). Hereafter, the movement speed of the welding robot 1 in area 8 will also be referred to as the reference speed. Also, the amount of movement Mx of the welding torch 13 in the vertical direction x is constant (hereinafter referred to as the vertical movement reference value). The amount of movement Mz of the welding torch 13 in the forward / backward direction z is constant (hereinafter referred to as the forward / backward movement reference value). The amount of movement M of the welding torch 13 around the first axis B The first axis rotation reference value is constant (hereinafter also referred to as the first axis rotation reference value), and the welding torch 13 is rotated vertically downward around the first axis. The amount of movement M of the welding torch 13 around the second axis T This is constant and is 0 (zero). That is, when viewed along the vertical direction x, the welding torch 13 is always perpendicular to the left-right direction y (i.e., the straight section 8b of the steel pipe 8), which is the direction of travel of the welding robot 1.

[0138] This section explains the control mechanisms in Area 5. In Area 5, the welding robot 1's movement speed is greater than the reference speed. That is, the welding robot 1 instantaneously accelerates to its movement speed in Area 5. Instantaneously means the moment it arrives in Area 5 from Area 8. After that, the welding robot 1 continues to decelerate at a predetermined negative acceleration from the starting position Pg5 in Area 5 to the ending position Pg6. Even in this case, the welding robot 1's movement speed is greater than the reference speed. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz decreases from the reference value for forward and backward movement as the welding robot 1 moves from position Pg5 to position Pg6. In other words, as the welding robot 1 moves from position Pg5 to position Pg6, the welding torch 13 moves in a direction that approaches the steel pipe 8. Travel amount M B As the welding robot 1 moves from position Pg5 to position Pg6, the first axis rotation reference value increases. In other words, as the welding robot 1 moves from position Pg5 to position Pg6, the vertical downward tilt of the welding torch 13 increases. Travel amount M T This value decreases from 0 as the welding robot 1 moves from position Pg5 to position Pg6. In other words, when viewed along the vertical direction x, as the welding robot 1 moves from position Pg5 to position Pg6, the welding torch 13 tilts toward the opposite side of the direction of movement of the welding robot 1.

[0139] The control details in Area 6 will be explained. In Area 6, the welding robot 1's movement speed is greater than the reference speed, but less than its movement speed in Area 5. That is, the welding robot 1 instantaneously decelerates to its movement speed in Area 6. Instantaneously means the moment it arrives in Area 6 from Area 5. Furthermore, in the range from position Pg6 to the midpoint between position Pg6 and position Pg7, the welding robot 1 continues to accelerate with a predetermined positive acceleration from the starting position Pg6 in Area 6 to the aforementioned midpoint. Subsequently, in the range from the midpoint between position Pg6 and position Pg7 to position Pg7, the welding robot 1 continues to decelerate with a predetermined negative acceleration from the aforementioned midpoint to the ending position Pg7 in Area 6. Even in this case, the welding robot 1's movement speed is greater than the reference speed, but less than its movement speed in Area 5. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz decreases as the welding robot 1 moves from position Pg6 to an intermediate position between position Pg6 and position Pg7, and increases as the welding robot 1 moves from the intermediate position between position Pg6 and position Pg7 to position Pg7. In other words, the welding torch 13 moves toward the steel pipe 8 when the welding robot 1 is in the range from position Pg6 to the intermediate position between position Pg6 and position Pg7, and moves toward the steel pipe 8 when the welding robot 1 is in the range from the intermediate position between position Pg6 and position Pg7 to position Pg7. Travel amount M B decreases as the welding robot 1 moves from the position Pg6 to the intermediate position between the position Pg6 and the position Pg7, and increases as the welding robot 1 moves from the intermediate position between the position Pg6 and the position Pg7 to the position Pg7. Even in this case, the movement amount M B will not be smaller than the first axis rotation reference value. That is, as the welding robot 1 moves from the position Pg6 to the intermediate position between the position Pg6 and the position Pg7, the downward inclination of the welding torch 13 in the vertical direction becomes smaller, and as the welding robot 1 moves from the intermediate position between the position Pg6 and the position Pg7 to the position Pg7, the downward inclination of the welding torch 13 in the vertical direction becomes larger. The movement amount M T increases as the welding robot 1 moves from the position Pg6 to the position Pg7. Also, the movement amount M T becomes 0 when the welding robot 1 is located at the intermediate position between the position Pg6 and the position Pg7. That is, when viewed along the vertical direction x, when the welding robot 1 is located at the position Pg6 which is the end position of the area 5, the welding torch 13 is inclined to the side opposite to the advancing direction of the welding robot 1. As the welding robot 1 moves from the position Pg6 to the intermediate position between the position Pg6 and the position Pg7, the inclination of the welding torch 13 to the side opposite to the advancing direction of the welding robot 1 decreases, and when the welding robot 1 reaches the intermediate position between the position Pg6 and the position Pg7, the welding torch 13 is orthogonal to the advancing direction of the welding robot 1. Thereafter, as the welding robot 1 moves from the intermediate position between the position Pg6 and the position Pg7 to the position Pg7, the welding torch 13 inclines to the advancing direction side of the welding robot 1.

[0140] The control content in the area 7 will be described. In Area 7, the welding robot 1's movement speed is greater than the reference speed and also greater than its movement speed in Area 6. That is, the welding robot 1 instantaneously accelerates to its movement speed in Area 7. Instantaneously means the moment it arrives in Area 7 from Area 6. After that, the welding robot 1 continues to accelerate at a predetermined positive acceleration from the starting position Pg7 in Area 7 to the ending position Pg8. Even in this case, the welding robot 1's movement speed is greater than both the reference speed and its movement speed in Area 6. The displacement Mx is equal to the reference value for vertical movement. The amount of movement Mz decreases as the welding robot 1 moves from position Pg7 to position Pg8, and becomes equal to the reference value of forward / backward movement when the welding robot 1 reaches position Pg8. In other words, as the welding robot 1 moves from position Pg7 to position Pg8, the welding torch 13 moves away from the steel pipe 8. Travel amount M B This value decreases as the welding robot 1 moves from position Pg7 to position Pg8, and becomes equal to the first axis rotation reference value when the welding robot 1 reaches position Pg8. In other words, as the welding robot 1 moves from position Pg7 to position Pg8, the vertical downward tilt of the welding torch 13 decreases. Travel amount M T The coefficient of force decreases as the welding robot 1 moves from position Pg7 to position Pg8, and becomes 0 when the welding robot 1 reaches position Pg8. That is, when viewed along the vertical direction x, the welding torch 13 is tilted toward the direction of travel of the welding robot 1 when the welding robot 1 is at position Pg7, which is the end position of area 6. As the welding robot 1 moves from position Pg7 to position Pg8, the tilt of the welding torch 13 toward the direction of travel of the welding robot 1 decreases, and when the welding robot 1 reaches position Pg8, the welding torch 13 is perpendicular to the direction of travel of the welding robot 1.

[0141] In the welding system 100 according to this embodiment, the same effects as in the first embodiment can be obtained. In other words, the welding system 100 according to this embodiment includes a shape information acquisition unit 622 that acquires the first curvature center C1 of the curved portion 8a, and a setting unit that uses the first curvature center C1 acquired by the shape information acquisition unit 622 to set the welding conditions of the welding robot 1. Therefore, even if the circumferential length and center of curvature differ between the curved section 8a of the steel pipe 8 and the curved section 2a of the guide rail 2, the welding conditions are set using the first center of curvature C1 of the curved section 8a of the steel pipe 8 that is to be welded. This allows for good welding of the curved section 8a regardless of variations in the distance between the steel pipe 8 and the guide rail 2. Thus, good welding quality can be obtained.

[0142] Although the second embodiment is described separately from the first embodiment, it is possible to perform the welding process of the curved section 8a described in the second embodiment by generating a matrix U common to areas 5 to 7 and a matrix T corresponding to each of areas 5 to 7 in the welding system 100 of the first embodiment. In other words, the welding control of the first embodiment and the welding control of the second embodiment can be performed using a single welding system 100.

[0143] [Regarding the case where the first center of curvature C1 and the second center of curvature C2 coincide] The following describes the control method in the welding system 100 when the first curvature center C1 and the second curvature center C2 coincide. In this case, the circumferential distance between the steel pipe 8 (curved section 8a) and the guide rail 2 (curved section 2a) is constant. Therefore, the welding torch direction, aiming angle, and aiming position of the welding torch 13 are set according to the above welding conditions. <2> ~ <4> With the settings configured to satisfy the above conditions, welding can be performed that satisfies the above welding conditions by setting the movement speed of the welding robot 1 such that the tip of the welding torch 13 moves at the welding movement speed Vw. In this case, the movement speed of the welding robot 1 is constant.

[0144] It should be noted that the present invention is not limited to the embodiments described above with reference to the drawings, and various modifications are conceivable within its technical scope.

[0145] For example, in the above embodiment, the welding conditions are: <1> ~ <4> The following was described. However, welding conditions <1> ~ <4> The amount of movement of the welding robot 1 may be controlled to satisfy at least one of the following conditions.

[0146] In the above embodiment, the control targets of the welding system 100 are: the amount of movement of the welding torch 13 in the vertical x direction of the welding robot 1, Mx; the amount of movement of the welding robot 1 in the horizontal y direction, My; the amount of movement of the welding torch 13 in the forward / backward z direction of the welding robot 1, Mz; and the amount of movement of the welding torch 13 around the first axis, M. B , and the amount of movement M of the welding torch 13 around the second axis T This was described. However, the control target of the welding system 100 may be at least one of the above-mentioned displacement amounts.

[0147] In the above embodiment, the steel pipes 8 were arranged in a vertical direction, but the steel pipes 8 may also be arranged in a horizontal direction.

[0148] Furthermore, all or part of the functions of the welding system 100 may be implemented using hardware such as ASICs (Application Specific Integrated Circuits), PLDs (Programmable Logic Devices), or FPGAs (Field Programmable Gate Arrays). The program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. The program may also be transmitted via a telecommunications line.

[0149] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of Symbols]

[0150] 100 welding systems 1. Welding robot 2 Guide rails (rails) 2a Curve section 6 System Control Unit 8 Steel pipe 8a Curve section 13 Welding Torch 33. Forward and backward movement section (torch position changing section) 34. Vertical movement section (torch position changing section) 35. First moving part (torch direction changing part) 36. Second moving part (torch direction changing part) 620 Welding Robot Control Unit 621 Location information acquisition unit 622 Shape information acquisition unit (acquisition unit) 623 Center of curvature determination section (determination section) 624 Parameter setting section (setting section) 625 Welding time counting section 626 Area determination unit 627 Target Torch Position Calculation Unit (Setting Unit) 628 Movement amount setting unit (setting unit)

Claims

1. A welding system for controlling a welding robot that moves along a rail having a curved section, which is arranged along a steel pipe, and welds the curved section of the steel pipe, An acquisition unit that acquires the center of curvature of the curved portion of the steel pipe as the first center of curvature, The system includes a setting unit that sets the welding conditions of the welding robot using the first center of curvature acquired by the acquisition unit, The welding robot is equipped with a welding torch. The welding conditions include the welding torch orientation, which is the orientation of the welding torch relative to the curved portion of the steel pipe. A welding system characterized in that, when the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide, the welding conditions are set using the first center of curvature.

2. A welding system for controlling a welding robot that moves along a rail having a curved section, which is arranged along a steel pipe, and welds the curved section of the steel pipe, An acquisition unit that acquires the center of curvature of the curved portion of the steel pipe as the first center of curvature, The system includes a setting unit that sets the welding conditions of the welding robot using the first center of curvature acquired by the acquisition unit, The welding robot is equipped with a welding torch. The welding conditions include the target position of the welding torch, A welding system characterized in that, when the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide, the welding conditions are set using the first center of curvature.

3. The welding system according to claim 1 or 2, characterized in that the welding conditions differ depending on whether the first center of curvature and the second center of curvature coincide.

4. The welding torch is further provided with a torch direction changing unit for changing the direction of the welding torch. The setting unit sets the welding torch direction using the first curvature center and the second curvature center. The torch direction changing unit changes the direction of the welding torch so that the direction of the welding torch relative to the curved portion of the steel pipe matches the welding torch direction set by the setting unit. The welding system according to feature 1.

5. The welding torch orientation includes the orientation of the welding torch when, in a top view, the direction of the tip of the welding torch coincides with the normal direction of the curved portion of the steel pipe. The setting unit sets the direction of the welding torch according to the position of the welding robot. The welding system according to claim 1 or 4.

6. The torch direction changing unit includes a first rotating unit that can rotate the welding torch around a first axis parallel to the direction in which the welding robot moves, and a second rotating unit that can rotate the welding torch around a second axis parallel to the longitudinal direction of the steel pipe. One of the first and second rotating parts rotates the other together with the welding torch. The welding torch orientation includes the orientation of the welding torch when the tip of the welding torch is positioned in the groove of the steel pipe, as viewed along the direction in which the welding robot moves. The setting unit sets the direction of the welding torch according to the rotation by the one. The welding system according to feature 4.

7. The welding system according to any one of claims 1 to 6, characterized in that the welding conditions include a welding travel speed, which is the travel speed of the tip of the welding torch.

8. The welding robot is further equipped with a speed change unit that changes the movement speed of the welding robot, The setting unit sets the welding movement speed using the first center of curvature and the second center of curvature. The speed adjustment unit adjusts the movement speed of the welding robot so that the movement speed of the tip of the welding torch matches the welding movement speed set by the setting unit. The welding system according to feature 7.

9. The system further includes a robot position changing unit for changing the position of the welding robot, The setting unit sets the welding movement speed using the first center of curvature and the second center of curvature. The robot position changing unit changes the position of the welding robot so that the movement speed of the tip of the welding torch matches the welding movement speed set by the setting unit. The welding system according to feature 7.

10. The system further includes a torch position changing unit for changing the position of the welding torch, The setting unit sets the target position using the first center of curvature and the second center of curvature. The torch position changing unit changes the position of the welding torch so that the position of the welding torch matches the target position set by the setting unit. The welding system according to claim 2, characterized in that it is as described above.

11. A program for causing a computer to function as a welding system according to any one of claims 1 to 10.

12. A welding method performed by a welding system that controls a welding robot that moves along a rail having a curved section, which is arranged along a steel pipe, and welds the curved section of the steel pipe, An acquisition step in which the center of curvature of the curved portion of the steel pipe is acquired as the first center of curvature, The system includes a setting step of setting the welding conditions of the welding robot using the first center of curvature obtained in the acquisition step, The welding conditions include the welding torch orientation, which is the orientation of the welding torch of the welding robot relative to the curved portion of the steel pipe. A welding method characterized in that, in the setting step, if the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide, the welding conditions are set using the first center of curvature.

13. A welding method performed by a welding system that controls a welding robot that moves along a rail having a curved section, which is arranged along a steel pipe, and welds the curved section of the steel pipe, An acquisition step in which the center of curvature of the curved portion of the steel pipe is acquired as the first center of curvature, The system includes a setting step of setting the welding conditions of the welding robot using the first center of curvature obtained in the acquisition step, The welding conditions include the target position of the welding torch of the welding robot. A welding method characterized in that, in the setting step, if the first center of curvature and the second center of curvature, which is the center of curvature of the curved portion of the rail, do not coincide, the welding conditions are set using the first center of curvature.

14. A welding system for controlling a welding robot that moves along a rail having straight rail sections and curved rail sections along a steel pipe and welds a first straight section, a curved section, and a second straight section of a steel pipe, The welding torch of the welding robot, A torch direction changing unit for changing the direction of the welding torch, The system includes a control unit that controls the torch direction changing unit, The center of curvature of the curved section of the steel pipe is located closer to the center of the steel pipe than the center of curvature of the curved section of the rail. The control unit, When the tip of the welding torch is welding the straight section of the first steel pipe up to the starting position of the curved section of the steel pipe, the direction of the welding torch is controlled to be perpendicular to the straight section of the first steel pipe. When the tip of the welding torch is welding the curved portion of the steel pipe, the orientation of the welding torch is controlled to coincide with the normal direction of the curved portion of the steel pipe. When the tip of the welding torch is welding the straight section of the second steel pipe from the end position of the curved section of the steel pipe, the direction of the welding torch is controlled to be perpendicular to the straight section of the second steel pipe. A welding system characterized by the following features.

15. A welding system for controlling a welding robot that moves in a predetermined direction along a rail having a first straight section, a curved section, and a second straight section along a steel pipe, and welds the first straight section, the curved section, and the second straight section of the steel pipe of the steel pipe, The welding torch of the welding robot, A torch direction changing unit for changing the direction of the welding torch, The system includes a control unit that controls the torch direction changing unit, The center of curvature of the curved section of the steel pipe is located closer to the center of the steel pipe than the center of curvature of the curved section of the rail. The rail curve section has a rail curve start position which is the starting position, a rail curve end position which is the ending position, and a rail curve intermediate position which is an intermediate position between the rail curve start position and the rail curve end position. The steel pipe curve section has a starting position, which is the steel pipe curve start position, and an ending position, which is the steel pipe curve end position. The control unit, When the tip of the welding torch is welding the straight section of the first steel pipe up to the starting position of the curve of the steel pipe, the direction of the welding torch is controlled to be perpendicular to the straight section of the first steel pipe. When the tip of the welding torch is welding the curved portion of the steel pipe, As the welding robot moves along the first straight section of the rail to the starting position of the rail curve, the tilt of the welding torch toward the opposite side of the predetermined direction is controlled to increase. As the welding robot moves from the starting position of the rail curve to the intermediate position of the rail curve, the tilt of the welding torch toward the opposite side of the predetermined direction is controlled to decrease. As the welding robot moves from the intermediate position of the rail curve to the end position of the rail curve, the tilt of the welding torch toward the predetermined direction is controlled to increase. As the welding robot moves from the end position of the rail curve to the second straight section of the rail, the tilt of the welding torch toward the predetermined direction is controlled to decrease. A welding system characterized by the following features.

16. A welding system for controlling a welding robot that moves in a predetermined direction along a rail having straight sections and curved sections along a steel pipe, and welds the straight sections and curved sections of the steel pipe, The welding torch of the welding robot, A torch direction changing unit for changing the direction of the welding torch, A torch position changing unit for changing the position of the welding torch, The system includes a control unit that controls the torch direction changing unit and the torch position changing unit, The center of curvature of the curved section of the steel pipe is located closer to the center of the steel pipe than the center of curvature of the curved section of the rail. The rail curve section has a rail curve start position which is the starting position, a rail curve end position which is the ending position, and a rail curve intermediate position which is an intermediate position between the rail curve start position and the rail curve end position. The control unit, When the tip of the welding torch is welding the curved portion of the steel pipe, As the welding robot moves along the straight section of the rail to the starting position of the curved section of the rail, the welding torch is controlled to tilt more sharply in the direction opposite to the predetermined direction, bringing it closer to the steel pipe. As the welding robot moves from the starting position of the rail curve to the intermediate position of the rail curve, the tilt of the welding torch toward the opposite side of the predetermined direction is reduced, and the welding torch is controlled to move closer to the steel pipe. As the welding robot moves from the intermediate position of the rail curve to the end position of the rail curve, the tilt of the welding torch toward the predetermined direction increases, and the welding torch is controlled to move away from the steel pipe. As the welding robot moves from the end of the rail curve to the straight section of the rail, the tilt of the welding torch toward the predetermined direction becomes smaller, and the welding torch is controlled to move away from the steel pipe. A welding system characterized by the following features.

Images