Control method of welding robot, welding control device, welding system, welding method, and control program of welding robot

Abstract

To provide a control method of a welding robot having robot moving speed control corresponding to torch angle control in order to obtain excellent bead appearance, a welding control device, a welding system, a welding method, and a control program of the welding robot.SOLUTION: A control method of a welding robot is characterized in that: when only a guide rail out of the guide rail and a workpiece is a curved surface portion in a region I and a region III, controls of (A) to (D) are performed on the basis of a torch angle correction amount calculated and set by a control condition calculation unit, and controls of (E) to (G) are performed on the basis of a robot moving speed calculated and set by the control condition calculation unit; and meanwhile, when only the workpiece of the guide rail and the workpiece is a curved surface portion in the region I and the region III, controls of (H) to (K) are performed on the basis of the torch angle correction amount calculated and set by the control condition calculation unit, and controls of (L) to (N) are performed on the basis of the robot movement speed calculated and set by the control condition calculation unit.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a control method for a welding robot capable of automatically performing welding while moving on a guide rail, a welding control device, a welding system, a welding method, and a control program for a welding robot. [Background technology]

[0002] Conventionally, at construction sites, polygonal steel pipes (hereinafter also referred to as "workpieces" or "steel pipes") used for columns, beams, etc. are automatically welded by a welding robot attached to a guide rail. The corners of the polygonal steel pipe are curved in an arc shape, and the guide rails installed around the periphery of the polygonal steel pipe also have curved parts to match the corners of the polygonal steel pipe.

[0003] It is generally known that the difficulty of automatic welding varies depending on the relationship between the polygonal steel pipe and the curved part of the guide rail. Specifically, automatic welding becomes difficult when the center of curvature of the corner of the polygonal steel pipe is different from the center of curvature of the curved part of the guide rail (hereinafter also referred to as non-concentric circles). This is because, on the weld line in the area where either or both of the polygonal steel pipe and the guide rail are curved, a) the torch angle with respect to the welding position is not constant, and b) the torch tip speed (hereinafter also referred to as welding speed) is not constant, which causes poor bead appearance and spatters. Therefore, even when the corner of the polygonal steel pipe and the curved part of the guide rail are non-concentric, in order to maintain good welding quality and welding workability in automatic welding, it is necessary to incorporate a countermeasure welding robot control program in advance.

[0004] Welding robot control techniques aimed at ensuring good welding quality even when the corner of the workpiece and the curved portion of the guide rail are not concentric are disclosed in, for example, Patent Document 1 and Patent Document 2.

[0005] The invention of Patent Document 1 aims to ensure a good bead appearance even when the corner of the workpiece and the curved portion of the guide rail are not on concentric circles and there is a large difference in curvature between the corner of the workpiece and the curved portion of the guide rail. Patent Document 1 discloses a control technology that performs the steps of determining a torch position on the workpiece by a torch position determination unit, calculating a torch angle at the torch position by a torch angle calculation unit, and controlling the torch angle by a movable unit based on the calculated torch angle.

[0006] The invention of Patent Document 2 aims to provide a welding system capable of obtaining good welding quality even when the center of curvature of the curved portion is different between the steel pipe and the guide rail. In Patent Document 2, the center of curvature of the rail curved portion is located closer to the center of the steel pipe than the center of curvature of the curved portion of the steel pipe. The control unit controls the orientation of the welding torch so that it is perpendicular to the first steel pipe straight portion when the tip of the welding torch welds the first steel pipe straight portion to the start position of the curved portion of the steel pipe, controls the orientation of the welding torch so that it is aligned with the normal direction of the curved portion of the steel pipe when the tip of the welding torch welds the curved portion of the steel pipe, and controls the orientation of the welding torch so that it is perpendicular to the second steel pipe straight portion when the tip of the welding torch welds the second steel pipe straight portion from the end position of the curved portion of the steel pipe. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2022-1371 [Patent Document 2] JP 2023-17758 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the techniques of Patent Documents 1 and 2, the torch angle of the welding robot is controlled during welding to keep the torch angle constant relative to the welding position. In addition to controlling the torch angle, the speed of the welding robot moving on the guide rail (hereinafter also referred to as the robot movement speed) is controlled to keep the welding speed constant. However, there is no more precise control of the robot movement speed that takes into account the movement of the torch when controlling the torch angle.

[0009] When controlling the torch angle, the torch is driven in the forward and backward directions when the welding direction is set to the front. That is, the element for making the welding speed constant must take into account not only the robot movement speed but also the movement of the torch in the forward and backward directions. In other words, it is necessary to control the robot movement speed taking into account the forward and backward movement of the torch angle. In particular, the area before and after the boundary between the range where only one of the guide rail or the workpiece has a curved portion and the range where both the guide rail and the workpiece have curved portions is the range where the forward and backward directions of the torch angle change, and if the robot movement speed is not controlled taking into account the movement of the torch angle, the amount of deposition around the boundary will change, and the bead appearance will be convex or concave, resulting in poor bead appearance. Therefore, in order to obtain a good bead appearance, it is necessary to control the robot movement speed according to the torch angle control.

[0010] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a welding robot control method, a welding control device, a welding system, a welding method, and a welding robot control program having robot movement speed control in accordance with torch angle control in order to obtain a good bead appearance. [Means for solving the problem]

[0011] Therefore, the above object of the present invention can be achieved by the following configurations [1] to

[18] .

[0012] [1] A method for controlling a welding robot using a welding system including a guide rail having a curved portion for a workpiece having a corner, a welding robot that moves on the guide rail to arc-weld the workpiece, and a welding control device that controls the welding robot, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so as to achieve the welding conditions set by the welding condition setting unit; Equipped with a target position determination step of determining the torch target position based on at least guide rail information and workpiece information; A region determining step of determining a region based on the torch target position; a control condition determination step of calculating the control condition by the control condition calculation unit for each area determined in the area determination step and setting the control condition; having In the region determining step, the region to be determined is divided into at least the following regions I to IV, Region I: A region where only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which both the guide rail and the workpiece are curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which both the guide rail and the workpiece are straight lines In the control condition determination step, the control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the guide rail is the curved surface portion among the guide rail and the workpiece, The following controls (A) to (D) are performed based on the torch angle correction amount calculated and set by the control condition calculation unit, Control (A): Control is performed to tilt the torch angle in the welding forward direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I. Control (B): Control is performed to tilt the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (C): Control is performed to tilt the torch angle in the welding retreat direction from approximately the center position of the region II to approximately the end position of the region II. Control (D): Control is performed to tilt the torch angle toward the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding robot control method, comprising the steps of: (E) performing control on the robot; and (G) performing control on the robot; Control (E): In the region I, at least one of the following sections (a) to (c) is controlled: Section (a): A control section in which the vehicle decelerates at approximately the start position of the region I. Section (b): A control section in which the torch is accelerated at a first gradient within the region I or to a preset value of a predetermined torch target position. Section (c): A control section in which the torch accelerates toward the approximate end position of the region I at a second gradient or to a preset value of a predetermined torch target position. Control (F): In the region II, at least one of the following sections (d) to (f) is controlled: Section (d): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (e): A control section in which the vehicle decelerates within the region II to approximately the center position of the region II. Section (f): A control section for accelerating within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (G): In the region III, at least one of the following sections (g) to (h) is controlled: Section (g): A control section in which the torch is decelerated at a third gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (h): A control section in which the rotational speed is decelerated at a fourth gradient or to a preset value of a predetermined torch target position toward an approximate end position of the region III within the region III. [2] A method for controlling a welding robot using a welding system including a guide rail having a curved portion for a workpiece having a corner, a welding robot that moves on the guide rail to arc-weld the workpiece, and a welding control device that controls the welding robot, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so as to achieve the welding conditions set by the welding condition setting unit; Equipped with a target position determination step of determining the torch target position based on at least guide rail information and workpiece information; A region determining step of determining a region based on the torch target position; a control condition determination step of calculating the control condition by the control condition calculation unit for each area determined in the area determination step and setting the control condition; having In the region determining step, the region to be determined is divided into at least the following regions I to IV, Region I: A region where only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which both the guide rail and the workpiece are curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which both the guide rail and the workpiece are straight lines In the control condition determination step, the control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the workpiece among the guide rail and the workpiece is the curved surface portion, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (H) to (K) are performed: Control (H): Control for tilting the torch angle in the welding retreat direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I Control (I): Control for tilting the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (J): Control for tilting the torch angle in the welding forward direction from approximately the center position of the region II to approximately the end position of the region II. Control (K): Control for tilting the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding robot control method, comprising the steps of: (L) performing control on the robot; and (N) performing control on the robot; Control (L): Control at least one of the following sections (i) to (k) in the region I: Section (i): A control section in which acceleration occurs approximately at the start position of the region I. Section (j): A control section in which the torch is decelerated at a fifth gradient within the region I or to a preset value of the torch target position. Section (k): A control section in which the rotational speed is decreased toward the approximate end position of the region I at a sixth gradient or to a preset value of the torch target position. Control (M): Control at least one of the following sections (l) to (n) in the region II: Section (l): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (m): A control section for accelerating within the region II to approximately the center position of the region II. Section (n): A control section in which the vehicle decelerates within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (N): Control at least one of the following sections (o) to (p) in the region III: Section (o): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (p): A control section in which the torch is accelerated in the region III toward an approximate end position of the region III at an eighth gradient or to a preset value of a predetermined torch target position. [3] The absolute value of the second slope is greater than the absolute value of the first slope; The absolute value of the third slope is greater than the absolute value of the fourth slope. The method for controlling a welding robot according to [1], [4] In the region I, at least a control section is provided in which the vehicle momentarily decelerates at approximately the start position of the region I, In the region I, at least one of a control section in which acceleration is performed at the first gradient and a control section in which acceleration is performed at the second gradient toward an approximate end position of the region I is provided. The method for controlling a welding robot according to [1] or [2], [5] In a control section in which the vehicle accelerates with the second gradient toward an approximate end position of the region I, The target set value of the robot movement speed at the approximate end position of the region I is greater than the set value of the region IV. The method for controlling a welding robot according to any one of [1] to [3], [6] When the distances d2 and d1 in the welding direction of the region I and the region III are the same, A target set value of the robot movement speed at an approximate end position of the region I is set to a maximum speed in the region II, In the region II, a control section is provided in which the speed is reduced from an approximate start position of the region II, which is the maximum speed, to an approximate center position, and a control section is provided in which the speed is increased from an approximate center position of the region II to an approximate end position, with the speed being approximately the same as that at the approximate start position of the region II as a target setting value. The method for controlling a welding robot according to [5], [7] When the distances d2 and d1 in the welding direction of the region I and the region III are different, When the distance d2 in the welding direction in the region I is greater than the distance d1 in the welding direction in the region III, a target setting value of the robot movement speed at an approximate start position of the region II is set to a maximum speed in the region II; When the distance d1 in the welding direction of the region III is greater than the distance d2 in the welding direction of the region I, the target setting value of the robot moving speed at the approximate end position of the region II is set to the maximum speed in the region II. The method for controlling a welding robot according to [5],

[0013] [8] The control conditions further include a correction amount in the groove depth direction, Based on the correction amount in the groove depth direction calculated and set by the control condition calculation unit, control is performed to move away from the welding position from the start position of the region I to the center position of the region II, and control is performed to move closer to the welding position from the center position of the region II to the end position of the region III. The method for controlling a welding robot according to any one of [1] to [7],

[0014] [9] In the region I, at least a control section is provided in which instantaneous acceleration is performed approximately at the start position of the region I, In the region I, a control section in which the speed is decelerated at the fifth gradient and a control section in which the speed is decelerated at the sixth gradient toward an approximate end position of the region I are provided, The absolute value of the sixth slope is greater than the absolute value of the fifth slope. The method for controlling a welding robot according to [2],

[0015]

[10] The control conditions further include a correction amount in the groove depth direction, Based on the correction amount in the groove depth direction calculated and set by the control condition calculation unit, control is performed to move from the start position of the region I to the center position of the region II toward the welding position, and control is performed to move from the center position of the region II to the end position of the region III away from the welding position. The method for controlling a welding robot according to [2],

[0016]

[11] Based on the guide rail information and the workpiece information, it is determined whether the curved portion of the guide rail and the corner portion of the workpiece are located on a concentric circle or a non-concentric circle; If they are located on concentric circles, they are judged to be Type A, and if they are located on non-concentric circles, they are judged to be Type B or Type C. Furthermore, when the workpiece is positioned on a non-concentric circle, if only the guide rail is the curved portion of the guide rail and the workpiece in the regions I and III, the method determines that the workpiece is Type B, and if only the workpiece is the curved portion of the guide rail and the workpiece in the regions I and III, the method determines that the workpiece is Type C.

[12] Determine whether the curved portion of the guide rail and the corner of the workpiece are located on a concentric circle or a non-concentric circle based on a distance in the welding direction between the region I and the region III calculated based on the guide rail information and the workpiece information, or a preset distance in the welding direction between the region I and the region III. The method for controlling a welding robot according to

[11] ,

[13] A control of the robot movement speed from the section (c) of the region I to the section (g) of the region III, or a control of the robot movement speed from the section (k) of the region I to the section (o) of the region III, is controlled so as to be substantially symmetrical about a central position of the region II. The method for controlling a welding robot according to any one of [1] to

[12] ,

[14] A welding control device that installs a guide rail having a curved portion for a workpiece having a corner portion, and controls a welding robot that moves on the guide rail to arc-weld the workpiece, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so as to achieve the welding conditions set by the welding condition setting unit; Equipped with determining the torch target position based on at least guide rail information and workpiece information; determining a region based on the torch target position; The control condition calculation unit calculates the control condition for each of the determined regions, and sets the control condition; The areas to be determined are divided into at least the following areas I to IV: Region I: A region where only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which both the guide rail and the workpiece are curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which both the guide rail and the workpiece are straight lines The control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the guide rail is the curved surface portion among the guide rail and the workpiece, The following controls (A) to (D) are performed based on the torch angle correction amount calculated and set by the control condition calculation unit, Control (A): Control is performed to tilt the torch angle in the welding forward direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I. Control (B): Control is performed to tilt the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (C): Control is performed to tilt the torch angle in the welding retreat direction from approximately the center position of the region II to approximately the end position of the region II. Control (D): Control is performed to tilt the torch angle toward the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding control device, characterized in that the following controls (E) to (G) are performed based on the robot movement speed calculated and set by the control condition calculation unit. Control (E): In the region I, at least one of the following sections (a) to (c) is controlled: Section (a): A control section in which the vehicle decelerates at approximately the start position of the region I. Section (b): A control section in which the torch is accelerated at a first gradient within the region I or to a preset value of a predetermined torch target position. Section (c): A control section in which the torch accelerates toward the approximate end position of the region I at a second gradient or to a preset value of a predetermined torch target position. Control (F): In the region II, at least one of the following sections (d) to (f) is controlled: Section (d): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (e): A control section in which the vehicle decelerates within the region II to approximately the center position of the region II. Section (f): A control section for accelerating within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (G): In the region III, at least one of the following sections (g) to (h) is controlled: Section (g): A control section in which the torch is decelerated at a third gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (h): A control section in which the rotational speed is decelerated at a fourth gradient or to a preset value of a predetermined torch target position toward an approximate end position of the region III within the region III.

[15] A welding control device that installs a guide rail having a curved portion for a workpiece having a corner portion, and controls a welding robot that moves on the guide rail to arc-weld the workpiece, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so as to achieve the welding conditions set by the welding condition setting unit; Equipped with determining the torch target position based on at least guide rail information and workpiece information; determining a region based on the torch target position; The control condition calculation unit calculates the control condition for each of the determined regions, and sets the control condition; The areas to be determined are divided into at least the following areas I to IV: Region I: A region where only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which both the guide rail and the workpiece are curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which both the guide rail and the workpiece are straight lines The control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the workpiece among the guide rail and the workpiece is the curved surface portion, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (H) to (K) are performed: Control (H): Control for tilting the torch angle in the welding retreat direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I Control (I): Control for tilting the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (J): Control for tilting the torch angle in the welding forward direction from approximately the center position of the region II to approximately the end position of the region II. Control (K): Control for tilting the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding control device, characterized in that the following controls (L) to (N) are performed based on the robot movement speed calculated and set by the control condition calculation unit. Control (L): Control at least one of the following sections (i) to (k) in the region I: Section (i): A control section in which acceleration occurs approximately at the start position of the region I. Section (j): A control section in which the torch is decelerated at a fifth gradient within the region I or to a preset value of the torch target position. Section (k): A control section in which the rotational speed is decreased toward the approximate end position of the region I at a sixth gradient or to a preset value of the torch target position. Control (M): Control at least one of the following sections (l) to (n) in the region II: Section (l): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (m): A control section for accelerating within the region II to approximately the center position of the region II. Section (n): A control section in which the vehicle decelerates within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (N): Control at least one of the following sections (o) to (p) in the region III: Section (o): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (p): A control section in which the torch is accelerated in the region III toward an approximate end position of the region III at an eighth gradient or to a preset value of a predetermined torch target position.

[16] The welding robot;

[14] or

[15] , which controls the welding robot; and A welding system comprising:

[17] A welding method using the welding system described in

[16] .

[18] A program for causing the welding robot control method described in [1] or [2] to function in a welding control device that controls the welding robot. Effect of the Invention

[0017] According to the welding robot control method, welding control device, welding system, welding method, and welding robot control program of the present invention, in automatic welding performed by a welding robot moving on a guide rail, a good bead appearance can be obtained even if the work corner and the curved portion of the guide rail are not concentric.

[0018] In particular, according to the above configurations [1] to [2], in automatic welding performed by a welding robot moving on a guide rail, a good bead appearance can be obtained even if the work corner and the curved portion of the guide rail are not concentric.

[0019] According to the above configuration [3], the balance between the torch angle movement amount and the robot movement amount is improved, and the welding torch speed becomes more stable (constant), so that the deposition amount in regions I and III becomes more stable.

[0020] According to the above configuration [4], the bead appearance in region I is improved.

[0021] According to the above configuration [5], the speed of the welding torch can be stabilized (kept constant) by making the robot moving speed faster on the curved surface portion than on the straight surface portion.

[0022] When the robot movement speed in region II becomes high, depending on the welding speed conditions, the motor may be limited, making it impossible to obtain the desired robot movement speed, or if the speed becomes too high, the robot may run off the guide rail. The above configuration [6] can prevent such an event from occurring. If the robot movement speed cannot be accelerated, the feed speed (welding current) can be reduced to reduce the deposition speed, thereby controlling the deposition amount in region II.

[0023] According to the above configuration [7], even if the distance in the welding direction between the region I and the region III is different, a good bead appearance can be obtained.

[0024] According to the above configuration [8], the tip-base metal distance (extension length) and the welding target position can be kept constant, and the welding conditions can be kept constant.

[0025] According to the above configuration [9], the balance between the torch angle movement amount and the robot movement amount is improved, and the welding torch speed becomes more stable (constant), so that the deposition amount in regions I and III becomes more stable.

[0026] According to the above configuration

[10] , the tip-base metal distance (extension length) and the welding target position can be kept constant, and the welding conditions can be kept constant.

[0027] According to the above configuration

[11] , types A to C can be determined in a simple manner.

[0028] According to the above configuration

[12] , types A to C can be determined in a simple manner.

[0029] According to the above configuration

[13] , the bead appearance becomes symmetrical about the center position of the region II, resulting in a good appearance.

[0030] According to the above configurations

[14] to

[18] , in automatic welding performed by a welding robot moving on a guide rail, a good bead appearance can be obtained even if the work corner and the curved portion of the guide rail are not concentric. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a welding system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic side view of the portable welding robot shown in FIG. [Diagram 3] FIG. 3 is a perspective view of the portable welding robot shown in FIG. [Figure 4] FIG. 4 is a conceptual diagram showing the approximate linear movement mechanism. [Diagram 5] FIG. 5 is a perspective view of the portable welding robot shown in FIG. 3 when attached to a workpiece. [Figure 6] FIG. 6 is a diagram for explaining the positional relationship between the guide rail and an area S of a quarter corner of a polygonal square steel pipe when viewed from directly above in FIG. [Figure 7] Figures 7(a) to (c) are schematic diagrams explaining the positional relationship with the guide rail for each type in the 1 / 4 corner area of ​​a polygonal square steel pipe, with Figure 7(a) showing the positional relationship for Type A, Figure 7(b) showing the positional relationship for Type B, and Figure 7(c) showing the positional relationship for Type C. [Figure 8] FIG. 8 is a diagram for explaining the positional relationship between the guide rail and the region of the 1 / 4 corner of the polygonal square steel pipe when viewed from directly above in FIG. 4 in the case of Type C. [Figure 9] FIG. 9 is a diagram for explaining the positional relationship between the guide rail and the region of the 1 / 4 corner of the polygonal square steel pipe when viewed from directly above in FIG. 4 in the case of Type B. [Figure 10] FIG. 10 is a diagram for explaining the torch angle correction amount θt in region I in the case of type B. [Figure 11] FIG. 11 is a diagram for explaining the torch angle correction amount θt in region II in the case of Type B. [Figure 12] FIG. 12 is a diagram for explaining the torch angle correction amount θt in region III in the case of Type B. [Figure 13]Figure 13(a) is a graph showing the torch angle correction amount θt versus the robot position angle θ, and Figure 13(b) is a graph showing the robot movement speed versus the robot position when the speed change in the X-axis direction due to the approximate linear movement mechanism (R2 direction rotation mechanism) is not taken into account (the torch angle is not controlled). [Figure 14] FIG. 14(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ, and FIG. 14(b) is a graph showing the robot movement speed relative to the robot position. [Figure 15] FIG. 15(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ according to Modification 1, and FIG. 15(b) is a graph showing the robot movement speed relative to the robot position according to Modification 1. [Figure 16] FIG. 16(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ in Modification 2, and FIG. 16(b) is a graph showing the robot movement speed relative to the robot position in Modification 2. [Figure 17] FIG. 17(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ in Modification 3, and FIG. 17(b) is a graph showing the robot movement speed relative to the robot position in Modification 3. [Figure 18] FIG. 18(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ in Modification 4, and FIG. 18(b) is a graph showing the robot movement speed relative to the robot position in Modification 4. [Figure 19] FIG. 19(a) is a diagram showing the positional relationship between the welding torch and the workpiece in a straight section of the guide rail in Type B, and FIG. 19(b) is a diagram showing the positional relationship between the welding torch 200 and the workpiece in the center of the curved section of the guide rail in Type B. [Figure 20] Figure 20(a) is a schematic diagram showing an enlarged view of the groove periphery in a straight portion of a guide rail in type B, and Figure 20(b) is a schematic diagram showing an enlarged view of the groove periphery in the center of a curved portion of a guide rail in type B. [Figure 21]Figure 21(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ, Figure 21(b) is a graph showing the robot movement speed relative to the robot cut position, and Figure 21(c) is a graph showing the groove depth correction amount relative to the robot cut position. [Figure 22] FIG. 22 is a diagram for explaining the positional relationship with the guide rail in the region of the 1 / 4 corner of the polygonal square steel pipe in the case of Type C. [Figure 23] Figure 23(a) is a graph showing the torch angle correction amount θt relative to the work angle θ1, Figure 23(b) is a graph showing the robot movement speed relative to the robot cut position, and Figure 23(c) is a graph showing the groove depth correction amount relative to the robot cut position. [Figure 24] FIG. 24 is a diagram for explaining the positional relationship between the steel pipe and the guide rail when the distances d2, d1 in the welding direction are different in type B. [Diagram 25] FIG. 25(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ, and FIG. 25(b) is a graph showing the robot movement speed relative to the robot position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, a welding robot control method, a welding control device, a welding system, a welding method, and a welding robot control program according to an embodiment of the present invention will be described with reference to the drawings. Note that this embodiment is an example of a case in which a portable welding robot is used. The present invention is not limited to the configuration of this embodiment.

[0033] In addition, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0034] For example, the term "unit" or "device" in the embodiments is not limited to a physical configuration that is mechanically realized by hardware, but also includes a configuration whose functions are realized by software such as a program. Also, the functions of one configuration may be realized by two or more physical configurations, or the functions of two or more configurations may be realized by, for example, one physical configuration.

[0035] <Welding system configuration> 1 is a schematic diagram showing a configuration of a welding system according to an embodiment of the present disclosure. As shown in FIG 1, the welding system 50 includes a portable welding robot 100, a feeder 300, a welding power source 400, a shielding gas supply source 500, and a control device 600.

[0036] [Control device] The control device 600, which corresponds to the control device of the present disclosure, is connected to the portable welding robot 100 by a robot control cable 610, and is connected to the welding power source 400 by a power control cable 620. The control device 600 has a data holding unit 601 that holds information such as the operation pattern of the portable welding robot 100, the welding start position, the welding end position, the control conditions for controlling the portable welding robot 100 so as to satisfy the welding conditions described below, teaching data that sets the welding conditions at a predetermined torch target position, a database (hereinafter also referred to as DB) that sets the welding conditions based on groove shape information, guide rail information, and work information. The control device 600 sends commands to the portable welding robot 100 and the welding power source 400 based on this teaching data, and controls the operation and welding conditions of the portable welding robot 100. The control device 600 may have a memory, and the data holding unit 601 may be included in the memory. The memory corresponds to a storage device.

[0037] The control device 600 has a control unit 604. The control unit 604 includes a calculation unit 602 and a setting unit 603.

[0038] The calculation unit 602 includes a groove shape information calculation unit 602a that calculates groove shape information from detection data obtained by sensing, which will be described later, and a control condition calculation unit 602b that calculates at least the control amount of each axis of the welding robot. As will be described later, the control amount calculated by the control condition calculation unit 602b may be the correction amount of each axis of the portable welding robot 100, or may be the condition after correction.

[0039] The setting unit 603 includes a torch position setting unit 603a that sets a torch target position based on guide rail information and work information described later, a welding condition setting unit 603b that (a) acquires and sets welding conditions based on the groove shape information and DB, or (b) corrects and sets welding conditions of the teaching data based on the groove shape information and DB, and a control condition setting unit 603c that sets control conditions based on the control amount of each axis of the welding robot. The control unit 604 may further include a function block that realizes functions other than those described above. The control unit 604 may include a processor and performs various information processing in the control device 600.

[0040] Furthermore, the control device 600 may have a control program for controlling the portable welding robot 100 to perform groove width tracking, arc tracking, and the like. The control program is stored in a storage device such as a memory of the control device 600. A processor included in the control device 600 reads and executes the control program to control the portable welding robot 100. The control program has various functions related to the control of the portable welding robot 100.

[0041] Further, a controller (not shown) for teaching or manual operation of the portable welding robot 100 is connected to the control device 600. However, this is not limited to this, and the controller for manual operation or teaching and the control device 600, which is a controller having other control functions, may be integrated, or the portable welding robot 100 may include the control device 600. In this embodiment, signals are sent using the robot control cable 610 and the power supply control cable 620, but this is not limited to this, and signals may be sent wirelessly. From the viewpoint of usability at the welding site, it is preferable to separate the controller into two: a controller for teaching or manual operation of the portable welding robot 100, and the control device 600, which is a controller having other control functions.

[0042] [Welding power source] Welding power source 400 generates an arc between welding wire 211 and workpiece Wo by supplying power to welding wire 211, which is a consumable electrode, and workpiece Wo in response to a command from control device 600. Power from welding power source 400 is sent to wire feeder 300 via power cable 410, and is sent from wire feeder 300 to welding torch 200 via conduit tube 420.

[0043] Fig. 2 is a schematic side view of the portable welding robot shown in Fig. 1. Fig. 3 is a perspective view of the portable welding robot shown in Fig. 2. Referring also to Figs. 2 and 3, power from a welding power source 400 is supplied to a welding wire 211 via a contact tip at the tip of a welding torch 200. The welding current during welding may be a direct current or an alternating current, and the waveform is not particularly important. Thus, the current may be a pulse such as a square wave or a triangular wave.

[0044] Furthermore, welding power source 400 has, for example, power cable 410 connected to welding torch 200 as a positive electrode, and power cable 430 connected to workpiece Wo as a negative electrode. Note that this is the case where welding is performed with reverse polarity, and when welding is performed with positive polarity, the power cable of the positive electrode is connected to workpiece Wo, and the power cable of the negative electrode is connected to welding torch 200.

[0045] [Shielding gas supply source] The shielding gas supply source 500 is composed of a container filled with shielding gas, a valve, and other auxiliary members. The shielding gas is sent from the shielding gas supply source 500 to the feeder 300 via a gas tube 510. The shielding gas sent to the feeder 300 is sent to the welding torch 200 via a conduit tube 420. The shielding gas sent to the welding torch 200 flows inside the welding torch 200, is guided to the nozzle 210, and is ejected from the tip side of the welding torch 200. The shielding gas used in this embodiment may be, for example, argon (Ar), carbon dioxide (CO2), or a mixture of these.

[0046] [Feeding device] The feeder 300 pays out the welding wire 211 and feeds it to the welding torch 200. The welding wire 211 fed by the feeder 300 is not particularly limited, and for example, a solid wire or a flux-cored wire is used. There is no particular limit to the diameter of the welding wire, but in this embodiment, the preferred wire diameter is 1.6 mm at the upper limit and 0.9 mm at the lower limit.

[0047] Conduit tube 420 according to this embodiment has a conductive path formed on the outer skin side of the tube to function as a power cable, a protective tube for protecting welding wire 211 is disposed inside the tube, and a flow path for shielding gas is formed. However, conduit tube 420 is not limited to this, and for example, a power supply cable and a hose for supplying shielding gas may be bundled around a protective tube for feeding welding wire 211 to welding torch 200. Also, for example, a tube for feeding welding wire 211 and shielding gas and a power cable may be installed separately.

[0048] [Portable welding robot] 2 and 3, the portable welding robot 100 includes a guide rail 120, a robot body 110 that is installed on the guide rail 120 and moves along the guide rail 120, and a torch connection unit 130 that is placed on the robot body 110. The robot body 110 is mainly composed of a main body unit 112 that is installed on the guide rail 120, a fixed arm unit 114 that is attached to the main body unit 112, and a welding torch rotation drive unit 116 that is attached to the fixed arm unit 114 in a state that it can rotate in the direction of arrow R1.

[0049] Fig. 4 is a conceptual diagram showing approximate linear movement mechanism 180. Torch connection part 130 is attached to welding torch rotation drive part 116 via sliding table 169 and crank 170 in a state in which it can rotate in the direction of arrow R2, as shown in Fig. 4. Torch connection part 130 also includes torch clamp 132 and torch clamp 134 that fix welding torch 200, as shown in Fig. 3. Main body part 112 is provided with cable clamp 150 that supports conduit tube 420 that connects feeding device 300 and welding torch 200 on the side opposite to the side on which welding torch 200 is attached.

[0050] The main body 112 of the robot main body 110 includes an X-axis moving mechanism 181 that moves the robot main body 110 along the guide rail 120 in the X-axis direction, which is perpendicular to the plane of the paper in FIG. 2 and corresponds to the direction of the weld line, as indicated by the arrow X in FIG. 2. The main body 112 also includes a Y-axis moving mechanism 182 that moves the fixed arm 114 relative to the main body 112 via the slide support 113 in the Y-axis direction, which is perpendicular to the X-axis and Z-axis directions and corresponds to the width direction of the groove 10. The main body 112 also includes a Z-axis moving mechanism 183 that moves the robot main body 110 in the depth direction of the groove 10, which is perpendicular to the X-axis and Y-axis directions. Thus, in this embodiment, the welding progress direction is the X-axis, the groove width direction is the Y-axis, and the groove depth direction is the Z-axis, based on the position of the robot. The XYZ coordinates are defined as robot coordinates, and are distinguished from world coordinates (work coordinates) defined as XwYwZw coordinates described later.

[0051] The approximate linear movement mechanism 180 is composed of a sliding table 169 to which the torch connection part 130 is attached, a crank 170, and the welding torch rotation drive part 116. Specifically, the crank 170 is fixed to a rotating shaft 168 of a motor (not shown) fixed to the welding torch rotation drive part 116, and the tip of the crank 170 is connected to one end of the sliding table 169 by a connecting pin 171. The sliding table 169 also has a long groove 169a in the middle part, and a fixing pin 172 fixed to the welding torch rotation drive part 116 is slidably fitted into the long groove 169a.

[0052] As a result, when crank 170 is rotated about rotating shaft 168 by a motor (not shown), sliding table 169 rotates about fixed pin 172 as a fulcrum, and moves along long groove 169a while being guided by fitted fixed pin 172. That is, when crank 170 rotates as indicated by arrow R2 in Figures 3 and 4, torch connection part 130 to which welding torch 200 is attached rotates the tip of welding wire 211 at angle Θ along an approximate straight line indicated by imaginary line IL in Figure 4 with respect to the X-axis while tilting welding torch 200. R21 minute. In other words, the tip position of the welding wire 211 can move in the X-axis direction without changing in the groove depth direction (Z-axis direction). Note that in this embodiment, the mechanisms for moving in the X-axis direction include the above-mentioned X-axis movement mechanism 181 and approximate linear movement mechanism 180, and whichever mechanism is used, will be described simply as "X-axis direction". In addition, the tip position of the welding wire 211 is synonymous with the target position during welding, and may be rephrased as the welding target position, torch position, etc.

[0053] 2, the welding torch rotation drive unit 116 is rotatably attached to the fixed arm unit 114, and may be adjusted to an optimal angle in advance and fixed, or a mechanism may be provided for rotating in the direction of the arrow R1 by a motor. The direction of the arrow R1 is the direction of rotation around a center line extending in the X-axis direction.

[0054] As described above, the robot body 110 can move the welding torch 200, which is its tip, in three directions, i.e., the X-axis direction, the Y-axis direction, and the Z-axis direction, with five degrees of freedom, i.e., by the welding torch rotation drive unit 116 (R1 direction rotation mechanism), the approximate linear movement mechanism 180 (R2 direction rotation mechanism), the X-axis movement mechanism 181, the Y-axis movement mechanism 182, and the Z-axis movement mechanism 183. However, the robot body 110 is not limited to this, and may be movable with any number of degrees of freedom depending on the application. By configuring in this way, the tip of the welding wire 211 of the welding torch 200 attached to the torch connection unit 130 can be directed in any direction. That is, the robot body 110 can be driven in the X-axis direction on the guide rail 120. In addition, the welding torch 200 can be driven in the Y-axis direction, which is the width direction of the groove 10, or in the Z-axis direction, which is the depth direction of the groove 10. In addition, the torch angle can be controlled by tilting the welding torch 200 in the forward or backward direction, for example, by driving the crank 170. In this embodiment, when the welding torch 200 is perpendicular to the workpiece Wo (Θ R2 = 0) as the reference, and Θ when rotating in the forward angle direction R2 is positive, Θ when rotating in the backward angle direction R2is explained as negative.

[0055] An attachment member 140 such as a magnet is provided below the guide rail 120, and the guide rail 120 is configured so that it can be easily attached to and detached from the workpiece Wo by the attachment member 140. When setting the portable welding robot 100 on the workpiece Wo, the operator may set handles 160 on both sides of the portable welding robot 100 and set the portable welding robot 100 on the workpiece Wo, but generally, when providing guide rails 120 to a polygonal steel pipe, the guide rails 120 are positioned so as to go around the outer periphery of the steel pipe once, as described below, so the handles 160 on both sides are not provided in the positions shown in FIG.

[0056] <Robot system installation status for polygonal steel pipes (workpiece)> FIG. 5 is a perspective view of the portable welding robot 100 shown in FIG. 3 attached to a workpiece. As shown in FIG. 5, the guide rail 120 is attached to a polygonal square steel pipe Wo (hereinafter also referred to as the workpiece Wo) so as to follow the circumferential direction of the outer surface of the steel pipe. In the illustrated example, the workpiece Wo has four straight sections WL and four corners (curved sections) WC connecting the straight sections WL. The guide rail 120 is provided so as to go around the outer surface of the steel pipe via the mounting member 140. The guide rail 120 in this example has a shape having four straight sections 121 and four curved sections 122 connecting the straight sections 121.

[0057] The portable welding robot 100 is attached on the guide rail 120 with the welding torch 200 facing downward. FIG. 6 is a diagram for simply explaining the positional relationship between the guide rail 120 and the area S (area indicated by a broken line in FIG. 5) of the workpiece Wo when viewed from directly above in FIG. 5, where the line of the guide rail indicates the position where the guide rail 120 and the X-axis moving mechanism 181 are in contact, and the line of the steel pipe indicates the welding position. As shown in FIG. 5 and FIG. 6, in this embodiment, the workpiece Wo is used as a reference, and the height direction of the workpiece Wo (the vertical direction in FIG. 5) is the Zw axis, the welding direction of two opposing straight parts WL (lower left and upper right in FIG. 5) among the four straight parts WL is the Xw axis, and the welding direction of the other two opposing straight parts WL (upper left and lower right in FIG. 5) among the four straight parts WL is the Yw axis, which is perpendicular to the Zw axis and the Xw axis. In this way, the XwYwZw coordinates are defined as world coordinates (work coordinates) and are distinguished from the robot coordinates defined by the XYZ coordinates.

[0058] The guide rail 120 shown in Figs. 5 and 6 has a straight portion 121 and a curved portion 122 that are connected to each other, and boundary points 128s, 128e where the guide route changes at the boundary between the straight portion 121 and the curved portion 122. The boundary points 128s, 128e of the guide rail 120 have a boundary point 128s on the welding start side and a boundary point 128e on the welding end side for each curved portion 122 of the guide rail 120. In addition, the workpiece Wo has a straight portion WL and a corner portion (curved portion) WC that are connected to each other, and boundary points WCs, WCe between the straight portion WL and the corner portion WC. The boundary points WCs, WCe of the workpiece Wo have a boundary point WCs on the welding start side and a boundary point WCe on the welding end side for each corner portion WC of the workpiece Wo. Furthermore, the curved portion 122 of the guide rail has a center position CL, and the corner portion WC of the workpiece Wo has a center position C. w has.

[0059] Also, the distance between boundary point 128e and boundary point WCe in the Xw-axis direction is d1, and the distance between boundary point 128s and boundary point WCs in the Yw-axis direction is d2. Distances d1 and d2 refer to the distances in the range where either guide rail 120 or workpiece Wo is a curved portion (curved portion 122, corner portion WC) and the other is a straight portion (straight portion 121, straight portion WL). Here, distance d1 is the distance between the center of curvature O of curved portion 122 of guide rail 120 in the Xw-axis direction. A and the center of curvature O of the corner WC of the workpiece Wo B The distance d2 is the difference between the center of curvature O of the curved portion 122 of the guide rail 120 in the Yw-axis direction. A and the center of curvature O of the corner WC of the workpiece Wo B It can be said that this is the difference.

[0060] In addition, in the case where the guide rail information and the workpiece information described later have coordinate data with an arbitrary position on the center side of the workpiece Wo as the origin, the curvature center O of the curved portion 122 of the guide rail 120 is A The coordinates of are (Xw1, Yw1), and the center of curvature O of the corner WC of the workpiece Wo is B When the coordinates of are (Xw2, Yw2), the distance d1 and the distance d2 are the center of curvature O B Position of the center of curvature O A The distance d1 is calculated by Xw2-Xw1, and the distance d2 is calculated by Yw2-Yw1. By calculating in this manner, when the values ​​of d1 and d2 are 0, it can be determined that the curved portion 122 and the corner portion WC are located on a concentric circle, and when the values ​​are other than 0, they are located on a non-concentric circle. Furthermore, when the values ​​of d1 and d2 are positive, it can be determined that the guide rail 120 is the curved portion 122 and the workpiece Wo is the straight portion WL in the range of d1 and d2 as shown in FIG. 6, and when the values ​​of d1 and d2 are negative, it can be determined that the guide rail 120 is the straight portion WL and the workpiece Wo is the curved portion 122 in the range of d1 and d2. Therefore, it can be determined whether the type is Type B or Type C, which will be described later, by the positive and negative values ​​of d1 and d2.

[0061] Here, there are three types depending on the shape of the workpiece Wo and the shape of the guide rail 120, and FIG. 6 shows one of these types, type B. Below, explanation will be made based on FIG. 7(a)-(c). FIG. 7(a)-(c) are schematic diagrams explaining the positional relationship with the guide rail in the 1 / 4 corner area of ​​the workpiece Wo for each type, FIG. 7(a) shows the positional relationship of type A, FIG. 7(b) shows the positional relationship of type B, and FIG. 7(c) shows the positional relationship of type C. FIG. 8 is a diagram explaining the positional relationship with the guide rail 120 in the 1 / 4 corner area of ​​the workpiece Wo when FIG. 4 is viewed from directly above in the case of type C.

[0062] <Type A> In the type A shown in FIG. 7(a), the center of curvature O , which is the center position of the arc of the curved portion 122 of the guide rail 120, is A and the center of curvature O, which is the center position of the circular arc of the workpiece corner. B In the case of concentric circles, the distance R between the guide rail 120 and the workpiece (specifically, the distance between the rail position and the welding position of the workpiece Wo) is always constant, and the above-mentioned distance d1 and distance d2 do not exist (distance d1 = 0, distance d2 = 0).

[0063] <Type B> In the type B shown in FIG. 7B, the center of curvature O , which is the center position of the arc of the curved portion 122 of the guide rail 120, is A is the center of curvature O, which is the center position of the arc of the corner WC of the workpiece Wo. B In this case, the distance R becomes shorter as the distance approaches the center position CL of the curved portion 122 of the guide rail 120. B Position of the center of curvature O A The range of d1 and d2 is the range where the guide rail 120 is the curved portion 122 and the workpiece Wo is the straight portion WL.

[0064] <Type C> In the type C shown in FIG. 7(c) and FIG. 8, the center of curvature O A The center of curvature O, which is the center position of the arc of the corner WC of the workpiece Wo, is B In this case, the distance R becomes longer as it approaches the center position CL of the curved portion 122 of the guide rail 120. B Position of the center of curvature O A In the range of d1 and d2, the guide rail 120 is at the straight portion WL and the workpiece Wo is at the corner portion WC.

[0065] Since the control process is different for each of types A to C, it is necessary to determine which of types A to C the workpiece Wo corresponds to based on the guide rail information and the workpiece information. Therefore, first, it is determined whether the curved portion 122 of the guide rail 120 and the corner portion WC of the workpiece Wo are located on a concentric circle or a non-concentric circle based on the guide rail information and the workpiece information. If they are located on a concentric circle, it is determined to be type A, and if they are located on a non-concentric circle, it is determined to be type B or type C. Furthermore, if they are located on a non-concentric circle, if only the guide rail 120 is a curved portion among the guide rail 120 and the workpiece Wo in regions I and III, it is determined to be type B, and if only the workpiece Wo is a curved portion among the guide rail 120 and the workpiece Wo in regions I and III, it is determined to be type C.

[0066] When determining whether the curved portion 122 of the guide rail 120 and the corner portion WC of the workpiece Wo are located on a concentric circle or not, the determination may be based on the distances d2 and d1 in the welding direction of the areas I and III calculated based on the guide rail information and the workpiece information, or the distances d2 and d1 in the welding direction of the areas I and III that are set in advance. That is, if d1 and d2 are 0 (d1=d2=0), the type may be determined as Type A, and otherwise the type may be determined as either Type B or C. In addition, the "center of curvature O" may be determined based on the distances d2 and d1 in the welding direction of the areas I and III. B Position of the center of curvature O A When the distances d1 and d2 are calculated as "position of the object", if the distances d1 and d2 are positive values, the object may be determined as Type B, and if the distances d1 and d2 are negative values, the object may be determined as Type C.

[0067] Hereinafter, the control process for welding the corners WC of the non-concentric workpieces Wo of types B and C will be described.

[0068] <First embodiment: Type B control process> [Guide rail information, workpiece information settings] The guide rail information and the workpiece information may be input in advance to the data storage unit 601 of the control device 600 as CAD data or the like, or may be input in advance by an operator, or may be input by sensing before welding, which will be described later. The workpiece information includes the plate thickness of the workpiece Wo, the radius of curvature RB of the corner WC, the center of curvature O B The guide rail information includes the position of the curved portion 122 of the guide rail 120 (the coordinate position in the case of coordinate data), the distance of the straight line portion WL, the positions of the boundary points WCs and WCe, and the shape of the groove 10. AExamples of information obtained from the relationship between the guide rail information and the workpiece information include the position of the workpiece Wo (coordinate position in the case of coordinate data), the distance of the straight line portion 121, and the positions of the boundary points 128s and 128e. Examples of information obtained from the relationship between the guide rail information and the workpiece information include the distances d1 and d2, the distance R, and the like. In this embodiment, as the guide rail information and the workpiece information, at least the shape information of the groove 10 including the plate thickness of the workpiece Wo, the information of the distances d1 and d2, and the information of the distance R are required. Note that it is preferable that the information on the plate thickness of the workpiece Wo and the shape information of the groove 10 are input to the data storage unit from sensing before welding, and the information on the distances d1 and d2, and the information on the distance R are input in advance, but this is not limited to this.

[0069] Here, in this embodiment, the reason why the plate thickness of the workpiece Wo is required as workpiece information is due to the limited types of polygonal steel pipes that are commonly used. Specifically, roll-formed polygonal square steel pipes for building structures (BCP) and roll-formed polygonal square steel pipes for building structures (BCR) are examples. Generally, the radius of curvature of a BCP is calculated as 3.5t for the plate thickness t, and the radius of curvature of a BCR is 2.5t. In other words, if the type and plate thickness of the polygonal steel pipe are known, the radius of curvature RB or center of curvature O of the corner portion WC of the workpiece Wo can be calculated. B In other words, if there is no information on the type of polygonal steel pipe, the radius of curvature RB or the center of curvature O of the corner WC of the work Wo can be obtained. B The position information can be obtained in another way.

[0070] [Sensing] In this embodiment, a voltage is applied between the workpiece Wo and the welding wire 211, and a touch sensor is used as a detection means for sensing the surface of the groove 10 by utilizing a voltage drop phenomenon that occurs when the welding wire 211 comes into contact with the workpiece Wo. The detection means is not limited to the touch sensor of this embodiment, and an image sensor, a laser sensor, or a combination of these detection means may be used. However, it is preferable to use the touch sensor of this embodiment in view of the simplicity of the device configuration.

[0071] The sensing step before the start of welding is performed by touch sensing at an arbitrary groove shape detection position (hereinafter also referred to as the sensing position) with the above-mentioned touch sensor in order to extract groove shape information. The tip of the welding wire 211 is moved around the groove 10 to sense the welding position of the workpiece Wo. By identifying the position when the tip of the welding wire 211 touches the workpiece Wo, etc., the above-mentioned shape information of the groove 10 and the plate thickness of the workpiece Wo can be identified.

[0072] The sensing position is not particularly important, but in Type B, the control conditions described below have different control formulas for at least region IV (A4) shown in Figure 9 where the guide rail 120 and workpiece Wo are both straight sections (straight section 121, straight section WL), region I (A1) where the guide rail 120 is at the curved section 122 and the workpiece Wo is at the straight section WL on the welding start side, region II (A2) where the guide rail 120 is at the curved section 122 and the workpiece Wo is at the corner section WC (curved section), and region III (A3) where the guide rail 120 is at the curved section 122 and the workpiece Wo is at the straight section WL on the welding start side, so it is preferable to at least set the torch position (welding position) that is the boundary between these regions I to IV as the sensing position. That is, it is preferable to set at least the following as sensing positions: torch target position P1 when the robot is located at boundary point 128s, which is the start position of curved portion 122 of guide rail 120; torch target position P2 when the torch is located at boundary point WCs on the welding start side of corner WC of workpiece Wo; torch target position P3 when the torch is located at center position Cw of corner WC of workpiece Wo; torch target position P4 when the torch is located at boundary point WCe on the welding end side of corner WC of workpiece Wo; and torch target position P5 when the robot is located at boundary point 128e, which is the end position of curved portion 122 of guide rail 120; and by determining the sensing positions in this way, the region is determined. Hereinafter, torch target positions P1 to P5 may be referred to as sensing positions P1 to P5. Also, the robot positions on guide rail 120 when the torch target positions are P1 to P5 are Ap1 to Ap5, respectively.

[0073] After the sensing step, a groove shape information calculation step is performed in which the groove shape information calculation unit 602a of the calculation unit 602 calculates groove shape information and plate thickness from the detection data of the cross-sectional shape of the groove 10 at each sensing position obtained in the sensing step. Here, examples of the groove shape information include the groove angle of the groove 10, plate thickness, groove depth, estimated weld metal height, gap, and distance between the workpiece ends. After this groove shape information calculation step, a step is performed in which the calculated data is input to the data holding unit 601 as a set value. In this embodiment, in the groove shape information calculation step, at least the plate thickness, gap, etc. are calculated as groove shape information and input to the data holding unit 601 as a set value. In addition, in the groove shape information calculation step, if the gap is smaller than the wire diameter of the welding wire, the gap amount may be calculated as 0.

[0074] [Welding condition settings] Next, based on the data of the groove shape information inputted as the setting value to the data holding unit 601 and the DB, the setting value of the welding condition in the teaching program data is corrected or set. In this embodiment, for example, the welding current, the arc voltage, the welding speed, the weaving condition, the welding target position, and the tip-base metal distance (hereinafter also referred to as the protrusion length) are set or corrected. Note that the setting or correction means that the setting value is set when it has not yet been set, and that the setting value is corrected when it has already been set. Here, the weaving condition specifically includes the swing width, the weaving period, and the like.

[0075] In this embodiment, since multi-layer welding is common, it is a basic premise that the stack height per layer is constant in the straight and curved sections. Therefore, it is preferable to perform stack design based on the groove shape information, and set or correct the welding conditions based on the calculated stack design information. Here, the stack design information includes the number of stacks, the number of passes, the stack height (≒ height of one pass), etc., but the welding conditions are determined based on at least the calculated stack height value. For example, if the gap is larger at the welding end position than at the welding start position due to sensing, the gap width will widen as the welding progresses, so it is necessary to increase the deposition amount in order to keep the stack height constant. At this time, examples of welding conditions related to the deposition amount include wire feed speed and welding speed, and these welding conditions can be set or corrected based on the groove shape information and the stack design information. In this embodiment, from the viewpoint of ease of control, the wire feed speed setting value, welding current setting value, arc voltage setting value, extension length, and torch angle relative to the welding surface are constant in the straight and curved sections, and the deposition amount may be controlled to keep the build-up height constant by changing the welding speed conditions. In general, a welding power source has an optimal welding current value associated with each feed speed, so it is possible to set either the wire feed speed setting value or the welding current setting value.

[0076] Although the teaching point position (hereinafter also referred to as the torch target position) for setting or correcting the welding conditions is not particularly limited, since the welding conditions are determined based on the groove shape information, it is preferable to set the torch target position at least at the same position as the sensing position. Therefore, in this embodiment, since the sensing positions P1 to P5 are the same positions, hereinafter, they may be described as the torch target positions P1 to P5. If the welding conditions between the torch target positions are different, the conditions may be changed with a linear, curved or step-like gradient. For example, if the welding speed of the torch target position P1 is set to 30 cm / min and the welding speed of the torch target position P2 is set to 35 cm / min, the welding speed condition between P1 and P2 will change with a gradient according to the robot movement distance or time, etc.

[0077] [Control conditions for control] It is desirable to perform welding according to the welding conditions set for each of the torch target positions P1 to P5, which are teaching points. However, in the case of non-concentricity, the "welding speed = robot movement speed" does not necessarily occur according to the robot position A on the rail, and the "torch angle = angle Θ of the approximate linear movement mechanism 180" with respect to the welding surface of the workpiece Wo. R2 In other words, the robot movement speed and angle Θ R2 It is necessary to calculate the control conditions such as the above and set them for each target torch position.

[0078] Here, the control conditions refer to the conditions of the robot driving unit related to each welding condition. For example, the control condition related to the welding speed is the robot moving speed (condition of the X-axis moving mechanism 181), the control condition related to the target position in the groove width direction is the groove width direction position (condition of the Y-axis moving mechanism 182), the control condition related to the projection length and the target position in the groove width direction is the groove depth direction position (condition of the Z-axis moving mechanism 183), and the control condition related to the target torch angle is the torch angle Θ R2 (Conditions of the approximate linear movement mechanism 180 (R2 direction rotation mechanism)) The control conditions related to the target torch attitude angle are the torch attitude angle Θ R1 (Conditions for welding torch rotation drive unit 116 (R1 direction rotation mechanism)).

[0079] Here, unless otherwise specified, in the present invention, when the term "target torch angle" is used, it is a welding condition that indicates the torch angle with respect to the welding surface, and when the term "torch angle" is used simply, it is the torch angle Θ of the approximate linear movement mechanism 180 (R2 direction rotation mechanism). R2 When it is referred to as a "target torch attitude angle", it is a welding condition that indicates the torch attitude angle with respect to the welding surface, and when it is simply referred to as a "torch attitude angle", it is the torch attitude angle Θ of the welding torch rotation drive unit 116 (R1 direction rotation mechanism). R1 The torch angle is the angle of inclination in the X-axis direction, which is the direction of the weld line, and the torch posture angle is the angle of inclination in the Y-axis direction, which is perpendicular to the direction of the weld line.

[0080] In addition, the groove width direction position, groove depth direction position, torch angle Θ R2 The control condition for the torch attitude angle ΘR1 may be the amount of movement of each moving mechanism based on a reference position, and may be displayed as a correction amount (amount of change from the reference). For example, in this embodiment, the control condition for the torch angle, as described later, is the torch angle Θ R2 The torch angle correction amount θt based on 0° is used as a control condition, and the groove depth direction position is the groove depth direction correction amount, which is the amount of movement based on a predetermined projection length (0 position), is used as a control condition. Note that each reference value may be based on the conditions in region IV.

[0081] In the present invention, at least the control conditions of the torch angle and the robot moving speed must be controlled at appropriate timing in each region. Hereinafter, a description will be given of the torch angle correction amount θt for each torch target position calculated based on the welding robot position An on the guide rail, a calculation method for the robot moving speed, and the control process for the torch angle and the robot moving speed between each torch target position.

[0082] [Control method: Torch angle calculation method] A method for calculating the torch angle correction amount θt on the curved portion 122 of the guide rail 120 will be described with reference to Figs. 9 to 12. Fig. 9 is a diagram for explaining the positional relationship with the guide rail 120 in the region of the 1 / 4 corner of the workpiece Wo when Fig. 4 is viewed from directly above in the case of Type B. Fig. 10 is a diagram for explaining the torch angle correction amount θt in region I in the case of Type B. Fig. 11 is a diagram for explaining the torch angle correction amount θt in region II in the case of Type B. Fig. 12 is a diagram for explaining the torch angle correction amount θt in region III in the case of Type B. The calculation method of the torch angle correction amount θt is calculated for each of regions I to IV based on the robot position angle θ and the workpiece angle θ1 described later.

[0083] (Robot position angle θ) The welding robot is located at the center of curvature O AIn order to move on the curved portion 122 of the guide rail based on the above, the robot position angle θ in FIG. 10 to FIG. 12 is the welding robot position with respect to the center of curvature O A and the line segment LAn of the current welding robot position An (line segment O A An) and the Yw-axis direction (O A and Ap1) and the angle θ between them.

[0084] Figure 9 shows an example when the torch target angle is 0° (perpendicular to the welding surface), where the robot position on guide rail 120 at torch target position P1 is position Ap1 in Figure 9, the robot position on guide rail 120 at torch target position P2 is Ap2 in Figure 9, the robot position on guide rail 120 at torch target position P3 is Ap3 in Figure 9, the robot position on guide rail 120 at torch target position P4 is Ap4 in Figure 9, and the robot position on guide rail 120 at torch target position P5 is Ap5 in Figure 9. Note that the robot positions in Figure 9 are positions when the torch target angle is 0°, and the robot position on the guide rail at each torch position will change depending on the torch target angle.

[0085] In addition, since the welding robot moves in the direction from Ap1 to Ap5, the robot position angle θ is the line segment O A An and Xw axis directions (O A 9 to 12, the robot position angle θ can be expressed as 0° (the start position of curved section 122) when the current robot position An is at Ap1, 45° (the center position of curved section 122) when it is at Ap3, and 90° (the end position of curved section 122) when it is at Ap5. Note that, of course, when the welding direction is opposite to that in Figs. 9 to 12, the line segment LAn (line segment O A The angle between An) and the XYw axis direction is the robot position angle θ.

[0086] Here, since the relationship "D ≒ θ (rad) × RA" holds between the robot position angle θ at the welding robot position An and the distance D on the guide rail from the starting point Ap1 to the welding robot position An, the robot position angle θ may be converted into the moving distance D (mm) from the starting point Ap1.

[0087] (Work angle θ1) In Figs. 10 to 12, the work angle θ1 is the center of curvature O B and the line segment LBn of the current welding robot position An (line segment O B 9 to 12, the welding direction of the welding robot is the direction of movement from Ap1 to Ap5, so the work angle θ1 is expressed as the angle θ1 between the line segment LBn (line segment O B An and Xw axis directions (O B and the line segment connecting P2.

[0088] (Calculation of torch angle correction amount θt in area I) As shown in FIG. 10, in region I, when the torch target angle θs is 0° (perpendicular to the welding surface), the torch angle correction amount θt=robot position angle θ due to the alternate angle relationship. In this embodiment, the torch target positions in the region I are P1 and P2, so the robot position angle θ as the control condition for the P1 and P2 positions is the center of curvature O A Angle (0) between the line segment connecting Ap1 and the Xw axis direction, center of curvature O A The angle between the line segment connecting Ap2 and the Xw axis direction (sin -1 (d2 / RA)×180 / π)°, and the torch angle Θ at P1 and P2 positions R2 is set as the control condition.

[0089] In addition, the same applies to other areas, but when the torch target angle θs is 0° (perpendicular to the welding surface), the torch angle correction amount θt = torch angle Θ R2 However, if the torch target angle is not 0°, the torch angle Θ R2may be calculated as "torch angle correction amount θt+torch target angle θs." Furthermore, the torch angle correction amount θt between the torch target positions may be linearly interpolated.

[0090] (Calculation of torch angle correction amount θt in region II) As shown in Fig. 11, in region II, the torch angle correction amount θt is found from the difference between the robot position angle θ and the work angle θ1 (θt = θ - θ1). Specifically, it can be converted as tan θt = tan (θ - θ1) = (tan θ - tan θ1) / (1 + tan θ × tan θ1). Therefore, the torch angle correction amount θt is expressed as the following formula (1). θt=tan-1(tanθ-tanθ1) / (1+tanθ×tanθ1)...(1)

[0091] Here, if the welding robot position An is expressed in the XwYw coordinate system, the welding robot position An(Xw, Yw) is (RAcosθ, RAsinθ), and is expressed by the following formula (2). tanθ1=(RAsinθ-d2) / (RAcosθ-d1)...(2)

[0092] By substituting formula (2) into formula (1), the following formula (3) is obtained, and the torch angle correction amount θt in region II can be calculated. θt=tan-1(tanθ-((RAsinθ-d2) / (RAcosθ-d1)) / (1+tanθ×((RAsinθ-d2) / (RAcosθ-d1)))...(3) It should be noted that equation (3) is valid only in the range of 0≦θ1<90°.

[0093] In this embodiment, the torch target positions in region II are P2 to P4.

[0094] (Calculation of torch angle correction amount θt in region III) As shown in Fig. 12, in the region III, the torch angle correction amount θt is calculated as θt = θ - 90°. In this embodiment, since the torch target positions in the region III are P4 and P5, the robot position angle θ as the control condition for the P4 position and the P5 position is calculated by dividing the center of curvature O A The angle between the line segment connecting Ap4 and the Xw axis direction (90-sin -1 (d1 / RA)×180 / π)°, center of curvature O A The angle between P4 and P5 is Θ, which is the angle (90°) between the line segment connecting Ap5 and the Xw axis direction. R2 is set as the control condition.

[0095] In the region IV, it is not necessary to control the control conditions. Therefore, the control conditions in the region IV are reference values. In this embodiment, for example, the torch target angle θs=the torch angle Θ in the region IV R2 (That is, the torch angle correction amount θt is always 0.) In addition, it is preferable that the torch target angle θs is set to 0°.

[0096] As described above, in the torch angle control of areas I to III in type B, the torch angle correction amount θt varies as shown in Fig. 13(a). Fig. 13(a) is a graph showing the torch angle correction amount θt versus the robot position angle θ, and Fig. 13(b) is a graph showing the robot movement speed versus the robot position when the speed change in the X-axis direction by the approximate linear movement mechanism 180 (R2-direction rotation mechanism) is not taken into account (when the torch angle is not controlled).

[0097] That is, as shown in FIG. 13(a), the following controls (A) to (D) are performed based on the torch angle correction amount θt calculated and set by the control condition calculation unit 602b. Control (A): Control is performed to tilt the torch angle in the welding forward direction from approximately the start position of area I (torch target position P1) to approximately the end position of area I (torch target position P2) or near the end position of area I. Control (B): The torch angle is controlled to tilt in the welding retreat direction so that the torch angle correction amount θt approaches 0 or close to 0 from approximately the start position of region II (torch target position P2) to approximately the center position of region II (torch target position P3). Control (C): Control is performed to tilt the torch angle in the welding retreat direction from approximately the center position of region II (torch target position P3) to approximately the end position of region II (torch target position P4). Control (D): Control is performed to tilt the torch angle in the welding forward direction so that the torch angle correction amount θt approaches 0 or close to 0 from approximately the start position of region III (torch target position P4) to approximately the end position of region III (torch target position P5).

[0098] [Control method: Calculation method of robot movement speed] Like the other control conditions, the robot movement speed is calculated based on the torch target positions P1 to P5, which are teaching points. That is, in this embodiment, the robot movement speed at the torch target positions P1 to P5 is calculated.

[0099] 13(b), a conventional robot movement speed control technique that does not take into account the speed change in the X-axis direction by the approximate linear movement mechanism 180 (R2 direction rotation mechanism) will be described. In this case, the robot movement speed Vn set at each of the torch target positions P1 to P5 is calculated by the following formula (4). Vn = RA / Ln × V0 … (4)

[0100] In this embodiment, since the torch target positions are P1 to P5, n is an integer from 1 to 5. RA is the radius of curvature of the curved portion 122 of the guide rail 120, and Ln is the distance between the torch position at each of the torch target positions P1 to P5 and the center of curvature O of the curved portion 122 of the guide rail 120. A Distance (line segment O A For example, in P1, the torch target position P1 and the center of curvature O A The distance between the two points is L1. The value of Ln can also be calculated based on the R value described below (Ln=RA-Rn).

[0101] In addition, "V0" is the robot movement speed setting value in region IV, and since the robot movement speed setting value and the welding speed setting value in region IV are equal, in this embodiment, the robot movement speed setting value in region IV is set as the reference robot movement speed setting value V0.

[0102] The robot movement speed on the curved surface at this time is as shown in Figure 13(b). Specifically, in region IV before reaching torch target position P1, the robot movement speed is V0. When the torch target position P1 is reached, the robot movement speed instantaneously accelerates to V1 = RA / L1 x V0, and then gradually decelerates until the robot reaches torch target position P3. When the torch target position P3 is reached, the robot movement speed gradually accelerates to V5 = RA / L5 x V0 from torch target position P3 to P5. When the torch target position P5 is reached, the robot movement speed instantaneously decelerates to V0.

[0103] However, as in the subject of the present invention, when the torch angle is set as a control condition, the torch angle ΘR2 varies by the approximate linear movement mechanism 180 (R2 direction rotation mechanism) and the welding torch 200 moves in the X-axis direction. Therefore, it is necessary to control the robot movement speed in each of the regions I to IV, taking into account the range of movement in the X-axis direction by the approximate linear movement mechanism 180.

[0104] In the present invention, by performing at least the following control (E) in region I, the bead appearance in the range of region I (range from torch target position P1 to P2) of the workpiece Wo becomes good. Control (E): In region I, at least one of the following sections (a) to (c) is controlled: Section (a): A control section in which deceleration occurs approximately at the start position of region I (torch target position P1). Section (b): A control section in which the torch accelerates at a first gradient within region I or to a preset value of a predetermined torch target position. Section (c): A control section in which the torch is accelerated toward the approximate end position of region I (torch target position P2) at a second gradient or to a preset value of the torch target position P2.

[0105] In addition, the control (E) preferably includes two of the control sections (a) to (c), and more preferably includes all of the control sections (a) to (c), which improves the bead appearance. In particular, the control section (c) is important for improving the bead appearance in the vicinity of the torch target position P2.

[0106] Furthermore, by performing at least the following control (F) in region II, the bead appearance in the range of region II (range of torch target positions P2 to P4) of the workpiece Wo becomes good. Control (F): In region II, control at least one of the following sections (d) to (f) is performed. Section (d): A control section in which the speed is accelerated or decelerated at approximately the start position of region II (torch target position P2) depending on the speed at approximately the end position of region I. Section (e): A control section in which the rotational speed is reduced to approximately the center position (torch target position P3) of region II. Section (f): A control section for accelerating within region II from approximately the center position (torch target position P3) of region II to approximately the end position (torch target position P4) of region II.

[0107] It is preferable that the control (F) includes two controls, namely, control sections (e) and (f).

[0108] Furthermore, by performing at least the following control (G) in region III, the bead appearance in the range of region III of the workpiece Wo (the range from torch target position P4 to P5) becomes good. Control (G): In region III, at least one of the following sections (g) to (h) is controlled: Section (g): A control section in which the rotational speed is decelerated at a third gradient at approximately the start position of region III (torch target position P4) or to a preset value of the torch target position. Section (h): A control section in which the rotational speed is decelerated at a fourth gradient or to a preset value of the torch target position within the region III toward the approximate end position of the region III (the torch target position P5).

[0109] It is preferable that the control (G) includes two controls, that is, control sections (g) and (h).

[0110] As described above, by performing the above-mentioned control for each of regions I to III, it is possible to improve the bead appearance around the entire circumference of the workpiece, and in the most preferable control, as shown in Figures 14(a) and (b), control (E) of region I includes all of the control sections (a) to (c), control (F) of region II includes two control sections (e) and (f), and control (G) of region III includes two control sections (g) and (h). Figure 14(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ, and Figure 14(b) is a graph showing the robot movement speed relative to the robot position.

[0111] Based on FIGS. 14(a) and (b), the specific control process will be described as follows (1) to (9). (1) The robot movement speed V0 set in area IV is maintained until the robot reaches the torch target position P1 (robot position Ap1). (2) When the torch reaches the target position P1, it instantly decelerates. (3) After decelerating, the robot gradually accelerates (at the first gradient) to the torch target position P6 (robot position is Ap6). (4) Just before reaching the torch target position P2 (robot position is Ap2), the robot accelerates instantaneously (at a second gradient) up to the set value of the robot movement speed for the torch target position P2. (5) Gradually decelerate from torch target position P2 to P3 (robot position Ap3). (6) Gradually accelerate the torch from target position P3 to P4 (robot position Ap4). (7) When the torch reaches the target position P4, it instantly decelerates (at the third gradient). (8) After instantaneous deceleration, the robot gradually decelerates (at a fourth gradient) until it reaches the torch target position P5 (robot position Ap5). (9) When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 set in region IV.

[0112] Note that there is no particular restriction on the specific control method as long as it can perform the control as shown in Figs. 14(a) and (b), but as an example, a specific example of control will be described with reference to Figs. 9 and 14(a) and (b).

[0113] [Control of Area I] (Control section (a)) In the control section (a), as soon as the torch reaches target position P1, which is approximately the start position of region I, the robot movement speed is instantly decelerated to the robot movement speed setting value set for target torch position P1. The setting value depends on a function that is preset for target torch position P1 and the next target torch position (target torch position P6 in this embodiment).

[0114] For example, aT+bV0 or aT 2 It is sufficient to provide a function such as +bT+cV0, and in this embodiment, it is preferable that the function is a linear or quadratic function like these. Here, a, b, and c are coefficients, T is time or the moving distance of the robot (if weaving is performed, the distance for one period may be used), and V0 is the reference robot moving speed (the robot moving speed set value in region IV) as described above. Specifically, in the case of a function of aT+bV0, the intercept bV0 is the set value of the torch target position P1. In other words, at the same time as reaching the torch target position P1, the torch is decelerated to the value of bV0. Thereafter, as will be described later, the torch is accelerated from the torch target position P1 to the next torch target position (torch target position P6 in this embodiment) according to the coefficient a of the slope.

[0115] In addition to control using such a function, a new torch target position Pn may be set slightly ahead of the torch target position P1, and the robot movement speed between the torch target positions P1 and Pn may be set so as to decrease the robot movement speed between the torch target positions P1 and Pn.

[0116] (Control section (b)) In the control section (b), the robot accelerates from the robot movement speed setting value of the torch target position P1 at a first predetermined gradient until it reaches a torch target position P6 (robot position is Ap6) that has been added separately in advance within the region I. Note that the first gradient here refers to the coefficient of a in the case of the above-mentioned function aT+bV0, for example, and 2 In the case of the function +bT+cV0, it refers to the coefficients a and b. Also, the slope does not need to be set in advance by the function, and acceleration may be performed with the robot movement speed setting value of the next torch target position as the target value.

[0117] (Control section (c)) In the control section (c), the robot movement speed set value for the torch target position P6 and the robot movement speed set value for the torch target position P2 are set to the above-mentioned robot movement speed Vn = RA / Ln x V0. That is, when the torch target position P6 is reached, the robot is instantaneously accelerated to the robot speed set value V6 = RA / L6 x V0 for the torch target position P6, and by the time the torch target position P2 is reached or the torch target position P2 is reached, the robot speed set value V2 = RA / L2 x V0 for the torch target position P2 is reached. This instantaneous acceleration is the second gradient, which varies depending on the performance of the motor, and the faster (the steeper the gradient), the better.

[0118] The absolute value of the second gradient in the control section (c) is set to be larger than the absolute value of the first gradient in the control section (b). Note that another function may be provided in the section from the torch target position P6 to P2, and acceleration may be performed according to a predetermined arbitrary gradient. In addition, the target setting value Vn=RA / Ln×V0 of the robot movement speed at the approximate end position of region I is larger than the setting value V0 in region IV.

[0119] [Control of Area II] (Control section (d)) In the control shown in FIG. 9 and FIGS. 14(a) and (b), the torch target position P6 is a position close to P2, and V6≈V2, so that control in the control section (d) is not required.

[0120] (Control section (e)) In the control section (e), the robot movement speed is decelerated from torch target position P2 to P3 according to the robot movement speed set value calculated by Vn = RA / Ln x V0. The target setting value of the robot movement speed at approximately the end position of region I (torch target position P2) is the maximum speed in region II, and in the control section (e), the robot movement speed is decelerated from approximately the start position of region II (torch target position P2), where the maximum speed is reached, to approximately the center position (torch target position P3).

[0121] Since the robot moving speed in the region II is high, depending on the welding speed conditions, the motor may be limited, and the desired robot moving speed may not be obtained, or the robot may run off the guide rail 120 if it runs too fast. Therefore, in this embodiment, the robot moving speed is controlled from the torch target position P2 to P3 using the conventional formula Vn=RA / Ln×V0 as described above, and the feed speed (welding current) is reduced so that the deposition amount is approximately equal to that in the previous and following regions. In other words, the actual measured welding speed is slower than the preset welding speed by the speed at which the torch moves in the opposite direction to the welding line direction (welding retreat direction side) due to the torch angle correction, but the feed speed (welding current) is reduced to reduce the deposition speed, thereby controlling the deposition amount in the region II. Note that, when there is no problem with the motor or the runoff, a predetermined gain may be set, for example, RA / Ln×V0×d (d is a coefficient).

[0122] (Control section (f)) In the control section (f), the robot movement speed is accelerated according to the robot movement speed set value from the torch target position P3 to P4 calculated by Vn=RA / Ln×V0. In the control section (f), the robot is accelerated from the approximate center position (torch target position P3) of the region II to the approximate end position (torch target position P4) at a target speed approximately the same as that at the approximate start position (torch target position P2) of the region II. Note that such control to set the robot movement speed to the same maximum speed at the approximate start position and the approximate end position of the region II is performed when the distance d2 in the welding direction of the region I is the same as the distance d1 in the welding direction of the region III (d2=d1). The case where the distances d1 and d2 are different will be described later with reference to FIG. 24 and FIGS. 25(a) and (b).

[0123] Since the robot moving speed in the region II is high, depending on the welding speed conditions, the motor may be limited, and the desired robot moving speed may not be obtained, or the robot may run off the guide rail 120 if it runs too fast. Therefore, in this embodiment, the robot moving speed is controlled from the torch target position P3 to P4 using the conventional formula Vn=RA / Ln×V0 as described above, and the feed speed (welding current) is reduced so that the deposition amount is approximately equal to that in the previous and following regions. In other words, the actual measured welding speed is slower than the preset welding speed by the speed at which the torch moves in the opposite direction to the welding line direction (welding retreat direction side) due to the torch angle correction, but the feed speed (welding current) is reduced to reduce the deposition speed, thereby controlling the deposition amount in the region II. Note that, when there is no problem with the motor or the runoff, a predetermined gain may be set, for example, RA / Ln×V0×d (d is a coefficient).

[0124] [Control of Area III] (Control section (g)) In control section (g), when the torch target position P4 is reached, the robot movement speed is instantaneously decelerated between torch target positions P4 and P5 in accordance with a predetermined function. This instantaneous deceleration is set as a third gradient, and this gradient varies depending on the performance of the motor; the faster (the steeper the gradient), the better. The absolute value of the third gradient in control section (g) is set to be greater than the absolute value of the fourth gradient in the next control section (h). This function may be set so that the gradient is negative. For example, -a g T+b g V0 and -a g T 2 -b g T+c g V0. In addition, in order to set the torch target position P4 at T=0, the target value for instantaneous deceleration becomes the intercept of the function. g T+b g For V0, b g The value of V0 is the intercept of the above function, and -a g T 2 -b g T+c g For V0, cg The value of V0 is the intercept of the above function.

[0125] (Control section (h)) Based on the above function, the speed is instantly decelerated, and then gradually decelerated according to the function until the torch reaches the target position P5. As described above, the function is set so that the slope is negative. For example, -a g T+b g For V0, -a g With a slope of -a g T 2 -b g T+c g For V0, -a g and -b g In this embodiment, this gradient is referred to as a fourth gradient. When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 in the region IV.

[0126] As shown in Fig. 14(b), in order to improve the bead appearance, it is preferable that the graph relating to the robot movement speed is controlled so as to be approximately symmetrical about the center position of region II (torch target position P3). In the graph of Fig. 14(b), strictly speaking, there is no symmetry in the vicinity of the torch target positions P1 and P5, but the control of the robot movement speed from the control section (c) of region I to the control section (g) of region III is controlled so as to be approximately symmetrical about the center position of region II (torch target position P3). By controlling in this manner, the bead appearance also becomes approximately symmetrical about the center position of region II (torch target position P3).

[0127] It is most preferable to control the regions I, II, and III as shown in FIGS. 14(a) and (b), but they may be controlled as in the following modified examples 1 to 4, for example.

[0128] (Variation 1) 9 and 14(a) and (b), the control section (c) is provided by adding the torch target position P6, but for example, control may be performed as shown in Figures 15(a) and (b). Figure 15(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ according to Modification 1, and Figure 15(b) is a graph showing the robot movement speed relative to the robot position according to Modification 1.

[0129] 15(a) and (b), the condition for the torch target position P2 can be shifted from the boundary point WCs position toward the welding start side, and a control section (c) can be provided in which the robot movement speed can be accelerated to a robot movement speed Vn=RA / Ln×V0 within region I (between P1 and WcS in this case) before reaching region II. However, since the condition for the torch angle correction amount is also shifted toward the welding start side, it is preferable to add a torch target position P6 between torch target positions P1 and P2 as shown in FIG. 9 and FIG. 14(a) and (b).

[0130] (Variation 2) Fig. 16(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ according to Modification 2, and Fig. 16(b) is a graph showing the robot movement speed relative to the robot position according to Modification 1. As shown in Fig. 16(a), the control related to the torch angle correction amount θt is performed in the same manner as in Fig. 14(a), as in the above (A) to (D). As shown in Fig. 16(b), the control related to the robot movement speed is different from that in Fig. 14(b).

[0131] As shown in Fig. 16(b), control (E) of region I includes two control sections (a) and (b), control (F) of region II includes all of control sections (d) to (f), and control (G) of region III includes two control sections (g) and (h). That is, the control of Fig. 16(b) differs from that of Fig. 14(b) in that it does not include control section (c) but includes control section (d). In control section (d), the speed at approximately the end position of region I is lower than the speed required in region II, so control is performed to instantly accelerate at approximately the start position of region II (torch target position P2).

[0132] Based on FIG. 16(b), the specific control process will be described as follows (1) to (9). (1) The robot movement speed V0 set in area IV is maintained until the robot reaches the torch target position P1 (robot position Ap1). (2) When the torch reaches the target position P1, it instantly decelerates. (3) After decelerating, the robot gradually accelerates (at the first gradient) to the torch target position P2 (the robot position is Ap2). (4) When the torch reaches the target position P2 (the robot position is Ap2), it accelerates instantaneously. (5) Gradually decelerate to the torch target position P3 (robot position Ap3). (6) Gradually accelerate the torch from target position P3 to P4 (robot position Ap4). (7) When the torch reaches the target position P4, it instantly decelerates (at the third gradient). (8) After instantaneous deceleration, the robot gradually decelerates (at a fourth gradient) until it reaches the torch target position P5 (robot position Ap5). (9) When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 set in region IV.

[0133] (Variation 3) Fig. 17(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ according to Modification 3, and Fig. 17(b) is a graph showing the robot movement speed relative to the robot position according to Modification 3. As shown in Fig. 17(a), the control related to the torch angle correction amount θt is performed in the same manner as in Fig. 14(a), as in the above (A) to (D). As shown in Fig. 17(b), the control related to the robot movement speed is different from that in Fig. 14(b).

[0134] As shown in Fig. 17(b), control (E) in region I includes two control sections (b) and (c), control (F) in region II includes two control sections (e) and (f), and control (G) in region III includes two control sections (g) and (h). The control in Fig. 17(b) differs from that in Fig. 14(b) in that it does not include control section (a) in which deceleration occurs approximately at the start position of region I (torch target position P1) and control section in which acceleration occurs approximately at the start position of region IV (torch target position P5).

[0135] Based on FIG. 17(b), the specific control process will be described as follows (1) to (8). (1) The robot movement speed V0 set in area IV is maintained until the robot reaches the torch target position P1 (robot position Ap1). (2) Gradually accelerate (at a first gradient) from torch target position P1 to torch target position P6 (robot position is Ap6). (3) Just before reaching the torch target position P2 (robot position is Ap2), the robot accelerates instantaneously (at a second gradient) up to the set value of the robot movement speed for the torch target position P2. (4) Gradually decelerate from the torch target position P2 to P3 (robot position Ap3). (5) Gradually accelerate the torch from target position P3 to P4 (robot position Ap4). (6) When the torch reaches the target position P4, it instantly decelerates (at the third gradient). (7) After instantaneous deceleration, the robot gradually decelerates (at a fourth slope) until it reaches the torch target position P5 (robot position Ap5). (8) After the torch reaches the target position P5, the robot movement speed V0 is maintained.

[0136] (Variation 4) Fig. 18(a) is a graph showing the torch angle correction amount θt relative to the robot position angle θ according to Modification 4, and Fig. 18(b) is a graph showing the robot movement speed relative to the robot position according to Modification 4. As shown in Fig. 18(a), the control related to the torch angle correction amount θt is performed in the same manner as in Fig. 14(a), as in the above (A) to (D). As shown in Fig. 18(b), the control related to the robot movement speed is different from that in Fig. 14(b).

[0137] As shown in Fig. 18(b), the control (E) in region I includes two control sections (a and (c), the control (F) in region II includes two control sections (e and (f), and the control (G) in region III includes a control section (g). The control in Fig. 18(b) differs from that in Fig. 14(b) in that it does not include the control section (b) in region I or the control section (h) in region III.

[0138] Based on FIG. 18(b), the specific control process will be described as follows (1) to (9). (1) The robot movement speed V0 set in area IV is maintained until the robot reaches the torch target position P1 (robot position Ap1). (2) When the torch reaches the target position P1, it instantly decelerates. (3) After deceleration, a constant speed is maintained up to the torch target position P6 (robot position is Ap6). (4) Just before reaching the torch target position P2 (robot position is Ap2), the robot accelerates instantaneously (at a second gradient) up to the set value of the robot movement speed for the torch target position P2. (5) Gradually decelerate from torch target position P2 to P3 (robot position Ap3). (6) Gradually accelerate the torch from target position P3 to P4 (robot position Ap4). (7) When the torch reaches the target position P4, it instantly decelerates (at the third gradient). (8) After decelerating, the constant speed is maintained until the torch reaches the target position P5 (robot position is Ap5). (9) When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 set in region IV.

[0139] [Control method: Groove depth calculation method] Although the two control conditions of torch angle control and robot movement speed have been explained above, it is preferable to control the groove depth direction in addition to these control conditions. Fig. 19(a) is a diagram showing the positional relationship between the welding torch 200 and the workpiece Wo in the straight section 121 of the guide rail 120 in Type B, and Fig. 19(b) is a diagram showing the positional relationship between the welding torch 200 and the workpiece Wo in the center of the curved section 122 of the guide rail 120 in Type B.

[0140] 19(a) and 19(b), the R value is shown as the distance in the Z-axis direction between guide rail 120 and the tip position (welding position) of welding wire 211. In the case of Type B, the R value decreases toward the center of curved portion 122 of guide rail 120.

[0141] FIG. 20(a) is a schematic diagram showing an enlarged view of the groove 10 in the straight portion 121 of the guide rail 120 in type B, and FIG. 20(b) is a schematic diagram showing an enlarged view of the groove 10 in the center of the curved portion 122 of the guide rail 120 in type B. In the examples shown in FIG. 20(a) and (b), no control is performed in the groove depth direction. Therefore, as shown in FIG. 20(b), when the R value becomes shorter toward the center of the curved portion 122 of the guide rail 120, the tip-base metal distance (projection length) becomes shorter than that in FIG. 20(a), and the welding conditions change. In particular, in this example in which the welding wire 211 is inclined rather than perpendicular to the workpiece Wo, the welding target position also changes between FIG. 20(a) and FIG. 20(b). Therefore, in order to keep the welding conditions constant, a correction is required to move welding torch 200 away from workpiece Wo by the amount that the R value has become shorter (the amount that welding torch 200 and workpiece Wo have come closer).

[0142] Therefore, it is preferable to control the groove depth direction by the Z-axis movement mechanism 183 of the portable welding robot 100. Since the distance R of each torch target position P1 to P6 can be obtained based on the guide rail information and the work information, when the distance R in the region IV is set as a reference value Rs and the distance R of each torch target position P1 to P6 is set as Rn (for example, R1 for the torch target position P1 and R2 for the torch target position P2), the correction amount in the groove depth direction can be obtained as Rs-Rn. In this embodiment, the correction amount Rs-Rn in the groove depth direction is set as a control condition for each torch target position P1 to P6.

[0143] FIG. 21(a) is a graph showing the torch angle correction amount θt with respect to the robot position angle θ, FIG. 21(b) is a graph showing the robot movement speed with respect to the robot cut position, and FIG. 21(c) is a graph showing the groove depth correction amount with respect to the robot cut position. In the case of type B as shown in FIG. 9, Rs=R1=R5>R6>R2=R4>R3. Therefore, the groove depth correction amount calculated by Rs-Rn is a graph as shown in FIG. 21(c). In this way, based on the groove depth correction amount calculated and set by the control condition calculation unit 602b, control is performed to move away from the welding position from the start position (torch target position P1) of region I to the center position (torch target position P3) of region II, and control is performed to move closer to the welding position from the center position (torch target position P3) of region II to the end position (torch target position P5) of region III. As shown in FIG. 21(c), the conditions between the torch target positions P1 to P6 may be interpolated using a curve or may be linearly interpolated.

[0144] <Second embodiment: Type C control process> A method for calculating the torch angle correction amount θt on the curved portion 122 of the guide rail 120 will be described using Figures 22 and 23. Figure 22 is a diagram illustrating the positional relationship with the guide rail 120 in the region of the 1 / 4 corner of the polygonal square steel pipe Wo in the case of Type C. Figure 23(a) is a graph showing the torch angle correction amount θt with respect to the work angle θ1, Figure 23(b) is a graph showing the robot movement speed with respect to the robot cut position, and Figure 23(c) is a graph showing the groove depth correction amount with respect to the robot cut position.

[0145] (Calculation of torch angle correction amount θt in area I) As shown in FIG. 22, in region I, when the torch target angle θs is 0° (perpendicular to the welding surface), the torch angle correction amount θt may be set to θt=−θ1 with respect to the work angle θ1 due to the alternate angle relationship.

[0146] (Calculation of torch angle correction amount θt in region II) As shown in FIG. 22, in region II, the torch angle correction amount θt is found from the difference between the robot position angle θ and the workpiece angle θ1 (θt=−θ1+θ).

[0147] (Calculation of torch angle correction amount θt in region III) As shown in FIG. 22, in region III, the torch angle correction amount θt is calculated as θt=−θ1+90°.

[0148] In region IV, there is no need to control the control conditions. Therefore, the control conditions in region IV are reference values. In this embodiment, for example, the torch target angle θs=the torch angle ΘR2 in region IV (i.e., the torch angle correction amount θt is always 0). In addition, it is preferable that the torch target angle θs is 0°.

[0149] As described above, in the torch angle control in the regions I to III in type C, the torch angle correction amount θt varies as shown in FIG. 23(a).

[0150] That is, as shown in FIG. 23(a), the following controls (H) to (K) are performed based on the torch angle correction amount θt calculated and set by the control condition calculation unit 602b. Control (H): Control is performed to tilt the torch angle in the welding retreat direction from approximately the start position of area I (torch target position P1) to approximately the end position of area I (torch target position P2) or near the end position of area I. Control (I): Control is performed to tilt the torch angle in the welding forward direction so that the torch angle correction amount θt approaches 0 or close to 0 from approximately the start position of region II (torch target position P2) to approximately the center position of region II (torch target position P3). Control (J): Control is performed to tilt the torch angle in the welding forward direction from approximately the center position of region II (torch target position P3) to approximately the end position of region II (torch target position P4). Control (K): Control is performed to tilt the torch angle in the welding retreat direction so that the torch angle correction amount θt approaches 0 or close to 0 from approximately the start position of region III (torch target position P4) to approximately the end position of region III (torch target position P5).

[0151] [Control method: Calculation method of robot movement speed] Like the other control conditions, the robot movement speed is calculated based on the torch target positions P1 to P5, which are teaching points. That is, in this embodiment, the robot movement speed at the torch target positions P1 to P5 is calculated.

[0152] In this embodiment, by performing at least the following control (L) in region I, the bead appearance in the range of region I (range from torch target position P1 to P2) of the workpiece Wo becomes good. Control (L): Control at least one of the following sections (i) to (k) in region I: Section (i): A control section in which acceleration occurs at approximately the start position of region I (torch target position P1). Section (j): A control section in which the torch is decelerated at a fifth gradient in region I or to a preset value of the torch target position. Section (k): A control section in which the rotational speed is decelerated toward the approximate end position of the region I (the torch target position P2) at a sixth gradient or to a preset value of the torch target position P2.

[0153] Preferably, the control (L) includes two of the control sections (i) to (k), and more preferably includes all of the control sections (i) to (k) to improve the bead appearance. In particular, the control section (k) is important for improving the bead appearance in the vicinity of the torch target position P2.

[0154] Furthermore, by performing at least the following control (F) in region II, the bead appearance in the range of region II (range of torch target positions P2 to P4) of the workpiece Wo becomes good. Control (M): In region II, control at least one of the following sections (l) to (n) is performed. Section (l): A control section in which the speed is accelerated or decelerated at approximately the start position of region II (torch target position P2) depending on the speed at approximately the end position of region I. Section (m): A control section for accelerating to approximately the center position (torch target position P3) of region II within region II. Section (n): A control section in which the vehicle decelerates within region II from approximately the center position (torch target position P3) of region II to approximately the end position (torch target position P4).

[0155] It is preferable that the control (M) includes two controls, that is, control sections (m) and (n).

[0156] Furthermore, by performing at least the following control (N) in region III, the bead appearance in the range of region III (range of torch target positions P4 to P5) of the workpiece Wo becomes good. Control (N): In region III, control at least one of the following sections (o) to (p) is performed. Section (o): A control section in which the torch is accelerated at a seventh gradient at approximately the start position of region III (torch target position P4) or to a preset value of the torch target position. Section (p): A control section in which, within the region III, the torch is accelerated toward the approximate end position of the region III (the torch target position P5) at an eighth gradient or to a preset value of the torch target position.

[0157] It is preferable that the control (N) includes two controls, that is, control sections (o) and (p).

[0158] As described above, by performing the above-mentioned control for each of regions I to III, it is possible to improve the bead appearance around the entire circumference of the workpiece. In the most preferred control, as shown in Figure 23(b), control (L) of region I includes all of control sections (i) to (k), control (M) of region II includes two control sections (m) and (n), and control (N) of region III includes two control sections (o) and (p).

[0159] Based on FIG. 22 and FIG. 23(b), the specific control process will be described as follows (1) to (9). (1) The robot movement speed V0 set in area IV is maintained until the robot reaches the torch target position P1 (robot position Ap1). (2) When the torch reaches the target position P1, it accelerates instantaneously. (3) After accelerating, the robot gradually decelerates (at a fifth gradient) to the torch target position P6 (robot position is Ap6). (4) Just before reaching the torch target position P2 (robot position is Ap2), the robot movement speed is instantly decelerated (at a sixth gradient) to the set value of the robot movement speed for the torch target position P2. (5) Gradually accelerate the torch from target position P2 to P3 (robot position Ap3). (6) Gradually decelerate from torch target position P3 to P4 (robot position Ap4). (7) When the torch reaches the target position P4, it accelerates instantaneously (at the seventh gradient). (8) After instantaneous acceleration, the robot gradually accelerates (at an eighth gradient) until it reaches the torch target position P5 (robot position is Ap5). (9) When the torch reaches the target position P5, the robot movement speed is instantly decelerated to V0 set in region IV.

[0160] Note that there is no particular restriction on the specific control method as long as it can perform control as shown in FIG. 23(b), but as an example, a specific example of control will be described with reference to FIG. 23(b).

[0161] [Control of Area I] (Control Section (i)) In the control section (i), as soon as the torch reaches target position P1, which is approximately the start position of region I, the robot instantaneously accelerates to the robot movement speed setting value set for target torch position P1. The setting value depends on a function preset for target torch position P1 and the next target torch position (target torch position P6 in this embodiment).

[0162] This function can be set so that the slope is negative. For example, -aT+bV0 or -aT 2 -bT+cV0. In this embodiment, it is preferable that it is a linear or quadratic function like these. Here, a, b, and c are coefficients, T is time or the moving distance of the robot (if weaving is performed, it may be the distance of one period), and V0 is the reference robot moving speed (the robot moving speed set value in region IV) as described above. Specifically, in the case of a function of -aT+bV0, the intercept bV0 is the set value of the torch target position P1. In other words, as soon as the torch target position P1 is reached, it accelerates to the value of bV0. Thereafter, as described later, it decelerates from the torch target position P1 to the next torch target position (torch target position P6 in this embodiment) according to the slope coefficient -a.

[0163] In addition to control using such a function, a new torch target position Pn may be set slightly ahead of the torch target position P1, and the robot movement speed between the torch target positions P1 and Pn may be set so as to decrease the robot movement speed between the torch target positions P1 and Pn.

[0164] (Control Section (j)) In the control section (j), the robot decelerates from the robot movement speed setting value of the torch target position P1 at a predetermined fifth gradient until it reaches a torch target position P6 (robot position is Ap6) that has been added separately in advance within the region I. Note that the fifth gradient here refers to the coefficient of -a in the case of the above-mentioned function -aT+bV0, for example, and 2 In the case of the function -bT+cV0, it refers to the coefficients -a and -b. Also, the slope does not need to be set in advance by the function, and acceleration may be performed with the robot movement speed setting value of the next torch target position as the target value.

[0165] (Control Section (k)) In the control section (k), the robot movement speed set value for the torch target position P6 and the robot movement speed set value for the torch target position P2 are set to the above-mentioned robot movement speed Vn=RA / Ln×V0. That is, when the torch target position P6 is reached, the robot speed is instantly decelerated to the robot speed set value V6=RA / L6×V0 for the torch target position P6, and by the time the torch target position P2 is reached or the torch target position P2 is reached, the robot speed set value V2=RA / L2×V0 for the torch target position P2 is reached. This instantaneous deceleration is defined as the sixth gradient, which varies depending on the performance of the motor, and the faster (the steeper the gradient), the better.

[0166] The absolute value of the sixth gradient in the control section (k) is set to be greater than the absolute value of the fifth gradient in the control section (j). Note that another function may be provided in the section from the torch target position P6 to P2 to decelerate according to a predetermined arbitrary gradient. In addition, the target setting value Vn=RA / Ln×V0 of the robot movement speed at the approximate end position of region I is greater than the setting value V0 of region IV.

[0167] [Control of Area II] (Control Section (l)) In the control shown in FIG. 23(b), the torch target position P6 is a position close to P2, and since V6≈V2, control in the control section (l) is not required.

[0168] (Control section (m)) In the control section (m), the robot movement speed is accelerated from torch target position P2 to P3 according to the robot movement speed set value calculated as Vn = RA / Ln x V0. The target setting value of the robot movement speed at approximately the end position of region I (torch target position P2) is the minimum speed in region II, and in the control section (m), the robot accelerates from approximately the start position of region II (torch target position P2), which is the minimum speed, to approximately the center position (torch target position P3). In region II of type C, the maximum speed is reached at approximately the center position (torch target position P3).

[0169] (Control Section (n)) In the control section (n), the robot movement speed is decelerated according to the robot movement speed set value from torch target position P3 to P4 calculated by Vn = RA / Ln x V0. In the control section (n), the robot movement speed is decelerated from approximately the center position (torch target position P3) of region II to approximately the end position (torch target position P4) with approximately the same speed as approximately the start position (torch target position P2) of region II as the target set value. Note that this control to make the robot movement speed the same at approximately the start position and approximately the end position of region II is performed when the distance d2 in the welding direction of region I is the same as the distance d1 in the welding direction of region III (d2 = d1).

[0170] [Control of Area III] (Control Section (o)) In the control section (o), when the torch target position P4 is reached, the robot movement speed is instantaneously accelerated between the torch target positions P4 and P5 in accordance with a predetermined function. This instantaneous acceleration is set as the seventh gradient, which varies depending on the performance of the motor, and the faster (the steeper the gradient), the better. The absolute value of the seventh gradient in the control section (o) is set to be greater than the absolute value of the eighth gradient in the control section (p). This function may be set so that the gradient is positive. For example, g T+b g V0 and a g T 2 +b g T+c gV0. In addition, in order to set the torch target position P4 at T=0, the target value for instantaneous acceleration becomes the intercept of the function. g T+b g For V0, b g The value of V0 is the intercept of the above function, and a g T 2 +b g T+c g For V0, c g The value of V0 is the intercept of the above function.

[0171] (Control section (p)) Based on the above function, the speed is instantly decelerated, and then gradually accelerated according to the function until the torch reaches the target position P5. As described above, the function is set so that the slope is positive. For example, g T+b g For V0, a g With a slope of a g T 2 +b g T+c g For V0, a g and b g In this embodiment, this gradient is referred to as an eighth gradient. When the torch reaches the target position P5, the robot instantaneously decelerates to the robot movement speed V0 in the region IV.

[0172] As shown in Fig. 23(b), in order to improve the bead appearance, it is preferable that the graph relating to the robot movement speed is controlled so as to be approximately symmetrical about the center position of region II (torch target position P3). In the graph in Fig. 23(b), strictly speaking, there is no symmetry in the vicinity of the torch target positions P1 and P5, but the control of the robot movement speed from the control section (k) of region I to the control section (o) of region III is controlled so as to be approximately symmetrical about the center position of region II (torch target position P3). By controlling in this manner, the bead appearance also becomes approximately symmetrical about the center position of region II (torch target position P3).

[0173] [Control method: Groove depth calculation method] Regarding the above Type C, the two control conditions of torch angle control and robot movement speed have been described. In addition to these control conditions, it is preferable to perform control in the weld bead depth direction by the Z-axis movement mechanism 183 of the portable welding robot 100.

[0174] Since the distances of each torch target position P1 to P6 (refer to the R value in FIG. 19) can be obtained based on the guide rail information and the workpiece information, when the distance R in Region IV is used as the reference value Rs and the distances R of each torch target position P1 to P6 are set as Rn (for example, R1 for torch target position P1 and R2 for torch target position P2), the correction amount in the weld bead depth direction can be obtained as Rs - Rn. In this embodiment, the correction amount in the weld bead depth direction is set as a control condition for each of the torch target positions P1 to P6.

[0175] In the case of Type C as shown in FIG. 22, Rs = R1 = R5 < R6 < R2 = R4 < R3. Therefore, the correction amount in the weld bead depth direction calculated by Rs - Rn results in a graph as shown in FIG. 23(c). Thus, based on the correction amount in the weld bead depth direction calculated and set by the control condition calculation unit 602b, control to approach the welding position from the start position of Region I (torch target position P1) to the center position of Region II (torch target position P3) and control to move away from the welding position from the center position of Region II (torch target position P3) to the end position of Region III (torch target position P5) are performed. As shown in FIG. 23(c), the conditions between the torch target positions P1 to P6 may be complemented by a curve or may be linearly complemented.

[0176] <Modification Example: When the values of d1 and d2 are different> The above described the controls of types B and C where the curved portion 122 of the guide rail 120 and the corner portion WC of the work Wo are located on non-concentric circles, but in all cases, the welding direction distances d2 and d1 between region I and region III were the same (d1 = d2). Using FIGS. 24 and FIGS. 25(a) and (b), the case where the distances d2 and d1 are different will be described. FIG. 24 is a diagram for explaining the positional relationship between the steel pipe Wo and the guide rail 120 when the welding direction distances d2 and d1 are different in type B. FIG. 25(a) is a graph showing the torch angle correction amount θt with respect to the robot position angle θ, and FIG. 25(b) is a graph showing the robot moving speed with respect to the robot position.

[0177] For example, in type B, when the guide rail 120 is displaced in the Xw-axis direction or the Yw-axis direction compared to the case of FIG. 9, the distances d1 and d2 will be different. When the distances d1 and d2 are equal, it is preferable that the control of region II is symmetric with respect to the central position as described above. However, when the distances d1 and d2 are different, the control of region II is not symmetric, and it is controlled such that the value on the side of the region with the shorter distance becomes larger. For example, when the distance d1 is shorter than the distance d2 as shown in FIG. 24 (d2 > d1), the robot moving speed at the torch target position P2 is maximized.

[0178] That is, when the welding direction distances d2 and d1 between region I and region III are different, and when the welding direction distance d2 of region I is larger than the welding direction distance d1 of region III (d2 > d1), the target set value of the robot moving speed at the approximate start position (torch target position P2) of region II is set to the maximum speed in region II.

[0179] Although not shown, when the welding direction distances d2 and d1 between region I and region III are different, and when the welding direction distance d1 of region III is larger than the welding direction distance d2 of region I (d2 < d1), the target set value of the robot moving speed at the approximate end position (torch target position P4) of region II is set to the maximum speed in region II.

[0180] The present invention is not limited to the above-described embodiment, and modifications and improvements are possible as appropriate. [Explanation of symbols]

[0181] 10 Bevel 50 Welding System 100 Portable welding robot 110 Robot body 112 Main body 113 Slide support 114 Fixed arm part 116 Welding torch rotation drive unit 120 Guide Rail 121 Straight section 122 Curved section 128e,128s boundary point 130 Torch connection part 132,134 Torch clamp 140 Components 150 Cable clamp 160 Handles on both sides 168 Rotational Axis 169 Sliding Table 169a long groove 170 Crank 171 Connecting pin 172 Fixing pin 180 Approximate linear movement mechanism 181 X-axis movement mechanism 182 Y-axis movement mechanism 183 Z-axis movement mechanism 200 Welding Torch 210 Nozzle 211 Welding Wire 300 Feeding device 400 Welding power source 410,430 Power Cable 420 Conduit Tube 500 Shielding gas supply source 510 Gas tube 600 Control device 601 Data storage unit 602 Calculation section 602a Groove shape information calculation unit 602b Control condition calculation unit 603 Settings 603a Torch position setting unit 603b Welding condition setting section 603c Control condition setting section 604 Control section 610 Robot Control Cable 620 Power supply control cable

Claims

1. A method for controlling a welding robot using a welding system including a guide rail having a curved portion for a workpiece having a corner, a welding robot that moves on the guide rail to arc-weld the workpiece, and a welding control device that controls the welding robot, comprising: The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so that the welding conditions are set by the welding condition setting unit; Equipped with a target position determination step of determining the torch target position based on at least guide rail information and workpiece information; A region determining step of determining a region based on the torch target position; a control condition determination step of calculating the control condition by the control condition calculation unit for each area determined in the area determination step and setting the control condition; having In the region determining step, the region to be determined is divided into at least the following regions I to IV, Region I: A region in which only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which the guide rail and the workpiece are both curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which the guide rail and the workpiece are both straight lines In the control condition determination step, the control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the guide rail is the curved portion among the guide rail and the workpiece, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (A) to (D) are performed: Control (A): Control is performed to tilt the torch angle in the welding forward direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I. Control (B): Control is performed to tilt the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (C): Control is performed to tilt the torch angle in the welding retreat direction from approximately the center position of the region II to approximately the end position of the region II. Control (D): Control is performed to tilt the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding robot control method, comprising the steps of: performing the following controls (E) to (G) on the basis of the robot movement speed calculated and set by the control condition calculation unit: Control (E): In the region I, at least one of the following sections (a) to (c) is controlled: Section (a): A control section in which the vehicle decelerates approximately at the start position of the region I. Section (b): A control section in which the torch is accelerated at a first gradient within the region I or to a preset value of a predetermined torch target position. Section (c): A control section in which the torch is accelerated toward the approximate end position of the region I at a second gradient or to a preset value of a predetermined torch target position. Control (F): In the region II, at least one of the following sections (d) to (f) is controlled: Section (d): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (e): A control section in which the vehicle decelerates within the region II to approximately the center position of the region II. Section (f): A control section for accelerating within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (G): In the region III, at least one of the following sections (g) to (h) is controlled: Section (g): A control section in which the rotational speed is decelerated at a third gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (h): A control section in which the torch speed is decelerated at a fourth gradient or to a preset value of a predetermined torch target position toward an approximate end position of the region III within the region III.

2. A method for controlling a welding robot using a welding system including a guide rail having a curved portion for a workpiece having a corner, a welding robot that moves on the guide rail to arc-weld the workpiece, and a welding control device that controls the welding robot, comprising: The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so that the welding conditions are set by the welding condition setting unit; Equipped with a target position determination step of determining the torch target position based on at least guide rail information and workpiece information; A region determining step of determining a region based on the torch target position; a control condition determination step of calculating the control condition by the control condition calculation unit for each area determined in the area determination step and setting the control condition; having In the region determining step, the region to be determined is divided into at least the following regions I to IV, Region I: A region in which only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which the guide rail and the workpiece are both curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which the guide rail and the workpiece are both straight lines In the control condition determination step, the control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the workpiece among the guide rail and the workpiece is the curved portion, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (H) to (K) are performed: Control (H): Control for tilting the torch angle in the welding retreat direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I Control (I): Control for tilting the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (J): Control for tilting the torch angle in the welding forward direction from approximately the center position of the region II to approximately the end position of the region II. Control (K): Control for tilting the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding robot control method, comprising the steps of: (L) performing control for a robot moving speed calculated and set by the control condition calculation unit; Control (L): In the region I, at least one of the following sections (i) to (k) is controlled: Section (i): A control section in which acceleration occurs approximately at the start position of the region I. Section (j): A control section in which the rotational speed is decelerated at a fifth gradient within the region I or to a preset value of the torch target position. Section (k): A control section in which the rotational speed is decelerated toward the approximate end position of the region I at a sixth gradient or to a preset value of the torch target position. Control (M): In the region II, at least one of the following sections (l) to (n) is controlled: Section (l): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (m): A control section for accelerating within the region II to approximately the center position of the region II. Section (n): A control section in which the vehicle decelerates within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (N): In the region III, at least one of the following sections (o) to (p) is controlled: Section (o): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (p): A control section in which the torch is accelerated at an eighth gradient or to a preset value of a predetermined torch target position toward the approximate end position of the region III within the region III.

3. the absolute value of the second slope is greater than the absolute value of the first slope, The absolute value of the third slope is greater than the absolute value of the fourth slope.

2. The method for controlling a welding robot according to claim 1.

4. In the region I, at least a control section is provided in which the vehicle momentarily decelerates at approximately a start position of the region I, In the region I, at least one of a control section in which acceleration is performed at the first gradient and a control section in which acceleration is performed at the second gradient toward an approximate end position of the region I is provided.

2. The method for controlling a welding robot according to claim 1.

5. In a control section in which the vehicle accelerates with the second gradient toward an approximate end position of the region I, The target set value of the robot movement speed at the approximate end position of the region I is greater than the set value of the region IV.

2. The method for controlling a welding robot according to claim 1.

6. When the distances d2 and d1 in the welding direction of the region I and the region III are the same, A target set value of the robot movement speed at an approximate end position of the region I is set to a maximum speed in the region II, In the region II, a control section is provided in which the speed is decelerated from an approximate start position of the region II, which is the maximum speed, to an approximate center position, and a control section is provided in which the speed is accelerated from an approximate center position of the region II to an approximate end position, with the speed being approximately the same as that at the approximate start position of the region II as a target setting value.

6. The method for controlling a welding robot according to claim 5.

7. When the distances d2 and d1 in the welding direction of the region I and the region III are different, When the distance d2 in the welding direction in the region I is greater than the distance d1 in the welding direction in the region III, a target setting value of the robot movement speed at an approximate start position of the region II is set to a maximum speed in the region II; When the distance d1 in the welding direction in the region III is greater than the distance d2 in the welding direction in the region I, the target setting value of the robot moving speed at the approximate end position of the region II is set to the maximum speed in the region II.

6. The method for controlling a welding robot according to claim 5.

8. The control conditions further include a correction amount in the groove depth direction, Based on the correction amount in the groove depth direction calculated and set by the control condition calculation unit, control is performed to move away from the welding position from the start position of the region I to the center position of the region II, and control is performed to move closer to the welding position from the center position of the region II to the end position of the region III.

2. The method for controlling a welding robot according to claim 1.

9. In the region I, at least a control section is provided in which instantaneous acceleration is performed approximately at a start position of the region I, In the region I, a control section in which the speed is decelerated at the fifth gradient and a control section in which the speed is decelerated at the sixth gradient toward an approximate end position of the region I are provided, The absolute value of the sixth slope is greater than the absolute value of the fifth slope.

3. The method for controlling a welding robot according to claim 2.

10. The control conditions further include a correction amount in the groove depth direction, Based on the correction amount in the groove depth direction calculated and set by the control condition calculation unit, control is performed to approach the welding position from the start position of the region I to the center position of the region II, and control is performed to move away from the welding position from the center position of the region II to the end position of the region III.

3. The method for controlling a welding robot according to claim 2.

11. determining whether the curved portion of the guide rail and the corner portion of the workpiece are located on a concentric circle or a non-concentric circle based on the guide rail information and the workpiece information; If the location is on a concentric circle, it is determined to be Type A, and if the location is on a non-concentric circle, it is determined to be Type B or Type C. The welding robot control method according to claim 1 or 2, further comprising the steps of: if the workpiece is located on a non-concentric circle, determining that the workpiece is type B when only the guide rail is the curved portion of the guide rail and the workpiece in regions I and III; and determining that the workpiece is type C when only the workpiece is the curved portion of the guide rail and the workpiece in regions I and III.

12. determining whether the curved portion of the guide rail and the corner portion of the workpiece are located on a concentric circle or a non-concentric circle based on a distance in a welding direction between the region I and the region III calculated based on the guide rail information and the workpiece information, or a preset distance in a welding direction between the region I and the region III; The method for controlling a welding robot according to claim 11.

13. a control regarding the robot movement speed from the section (c) of the region I to the section (g) of the region III, or a control regarding the robot movement speed from the section (k) of the region I to the section (o) of the region III, is controlled so as to be substantially symmetrical about a central position of the region II; 3. The method for controlling a welding robot according to claim 1 or 2.

14. A welding control device that installs a guide rail having a curved portion for a workpiece having a corner portion, and controls a welding robot that moves on the guide rail to arc-weld the workpiece, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so that the welding conditions are set by the welding condition setting unit; Equipped with determining the torch target position based on at least guide rail information and workpiece information; determining a region based on the torch target position; The control condition calculation unit calculates the control condition for each of the determined regions, and sets the control condition; The region to be determined is divided into at least the following regions I to IV: Region I: A region in which only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which the guide rail and the workpiece are both curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which the guide rail and the workpiece are both straight lines The control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the guide rail is the curved portion among the guide rail and the workpiece, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (A) to (D) are performed: Control (A): Control is performed to tilt the torch angle in the welding forward direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I. Control (B): Control is performed to tilt the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (C): Control is performed to tilt the torch angle in the welding retreat direction from approximately the center position of the region II to approximately the end position of the region II. Control (D): Control is performed to tilt the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding control device, characterized in that the following controls (E) to (G) are performed based on the robot movement speed calculated and set by the control condition calculation unit. Control (E): In the region I, at least one of the following sections (a) to (c) is controlled: Section (a): A control section in which the vehicle decelerates approximately at the start position of the region I. Section (b): A control section in which the torch is accelerated at a first gradient within the region I or to a preset value of a predetermined torch target position. Section (c): A control section in which the torch is accelerated toward the approximate end position of the region I at a second gradient or to a preset value of a predetermined torch target position. Control (F): In the region II, at least one of the following sections (d) to (f) is controlled: Section (d): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (e): A control section in which the vehicle decelerates within the region II to approximately the center position of the region II. Section (f): A control section for accelerating within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (G): In the region III, at least one of the following sections (g) to (h) is controlled: Section (g): A control section in which the rotational speed is decelerated at a third gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (h): A control section in which the rotational speed is decelerated at a fourth gradient or to a preset value of a predetermined torch target position toward an approximate end position of the region III within the region III.

15. A welding control device that installs a guide rail having a curved portion for a workpiece having a corner portion, and controls a welding robot that moves on the guide rail and arc-welds the workpiece, The welding control device includes: a welding condition setting unit that sets welding conditions at a predetermined torch target position; a control condition calculation unit that calculates control conditions for controlling the welding robot so that the welding conditions are set by the welding condition setting unit; Equipped with determining the torch target position based on at least guide rail information and workpiece information; determining a region based on the torch target position; The control condition calculation unit calculates the control condition for each of the determined regions, and sets the control condition; The region to be determined is divided into at least the following regions I to IV: Region I: A region in which only one of the guide rail and the workpiece is a curved surface on the welding start position side. Region II: Region in which the guide rail and the workpiece are both curved surfaces Region III: A region where only one of the guide rail and the workpiece is a curved surface on the welding end position side. Region IV: Region in which the guide rail and the workpiece are both straight lines The control conditions include at least a torch angle correction amount and a robot movement speed, In the region I and the region III, when only the workpiece among the guide rail and the workpiece is the curved portion, Based on the torch angle correction amount calculated and set by the control condition calculation unit, the following controls (H) to (K) are performed: Control (H): Control for tilting the torch angle in the welding retreat direction from approximately the start position of the region I to approximately the end position of the region I or near the end position of the region I Control (I): Control for tilting the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region II to approximately the center position of the region II. Control (J): Control for tilting the torch angle in the welding forward direction from approximately the center position of the region II to approximately the end position of the region II. Control (K): Control for tilting the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or close to 0 from approximately the start position of the region III to approximately the end position of the region III. A welding control device, characterized in that the following controls (L) to (N) are performed based on the robot movement speed calculated and set by the control condition calculation unit. Control (L): In the region I, at least one of the following sections (i) to (k) is controlled: Section (i): A control section in which acceleration occurs approximately at the start position of the region I. Section (j): A control section in which the rotational speed is decelerated at a fifth gradient within the region I or to a preset value of the torch target position. Section (k): A control section in which the rotational speed is decelerated toward the approximate end position of the region I at a sixth gradient or to a preset value of the torch target position. Control (M): In the region II, at least one of the following sections (l) to (n) is controlled: Section (l): A control section in which the speed is accelerated or decelerated at approximately the start position of the region II according to the speed at approximately the end position of the region I. Section (m): A control section for accelerating within the region II to approximately the center position of the region II. Section (n): A control section in which the vehicle decelerates within the region II from approximately the center position of the region II to approximately the end position of the region II. Control (N): In the region III, at least one of the following sections (o) to (p) is controlled: Section (o): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III or to a preset value of a predetermined torch target position. Section (p): A control section in which the torch is accelerated at an eighth gradient or to a preset value of a predetermined torch target position toward the approximate end position of the region III within the region III.

16. The welding robot; The welding control device according to claim 14 or 15, which controls the welding robot; A welding system comprising:

17. A method of welding using the welding system of claim 16.

18. 3. A program for causing a welding control device that controls a welding robot to function according to the method for controlling a welding robot according to claim 1.

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