Welding robot control method, welding control device, welding system, and welding robot control program

Abstract

To obtain a good bead appearance even when a corner of a workpiece and a curved portion of a guide rail are not concentric in automatic welding performed by a welding robot moving on a guide rail. [Solution] In the step of determining the torch target position, three points are set as torch target positions on the curved portion of the workpiece: the boundary position between the curved portion and the straight portion of the workpiece; and in addition to the boundary position, at least three points are set: position Cw, which is approximately the center position of the curved portion; position WCs1, which is between the boundary position (welding start side) and the approximately center position; and position WCe1, which is between the approximately center position and the boundary position (welding end side).In the step of setting control conditions, the control conditions include a condition for the movement speed of the welding robot, and the movement speed of the welding robot sharply accelerates or decelerates at least near position WCs1 and position WCe1 on the curved portion of the workpiece, based on the movement speed of the welding robot set for each torch target position.

Description

[Technical Field]

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

[0002] Conventionally, at construction sites, polygonal steel pipes (hereinafter also referred to as "workpieces" or "steel pipes") used for columns, beams, etc. have been 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 polygonal steel pipe also have curved sections that 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 portion of the guide rail. Specifically, automatic welding becomes difficult when the center of curvature of the corner of the polygonal steel pipe differs from the center of curvature of the curved portion of the guide rail (hereinafter referred to as "non-concentric"). This is because, along the weld line in areas where either or both of the polygonal steel pipe and the guide rail are curved, a) the torch angle relative to the welding position is not consistent, or b) the torch tip speed (hereinafter referred to as "welding speed") is not as set, resulting in poor bead appearance and spatter. Therefore, to maintain good weld quality and welding workability in automatic welding even when the corner of the polygonal steel pipe and the curved portion of the guide rail are non-concentric, it is necessary to incorporate countermeasures into the welding robot control program in advance.

[0004] Patent Document 1 and Patent Document 2, for example, disclose welding robot control techniques that aim to ensure good welding quality even when the corners of the workpiece and the curved portions of the guide rail are not concentric.

[0005] The invention described in 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 concentric 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 the torch position on the workpiece by a torch position determination unit, calculating the 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 described in Patent Document 2 aims to provide a welding system that can obtain good welding quality even when the centers of curvature of the curved sections of the steel pipe and the guide rail are different. In Patent Document 2, the center of curvature of the curved section of the rail is located closer to the center of the steel pipe than the center of curvature of the curved section of the steel pipe. The control unit controls the orientation of the welding torch so that it is perpendicular to the first straight section of the steel pipe when the tip of the welding torch welds a first straight section of the steel pipe up to the start position of the curved section of the steel pipe, controls the orientation of the welding torch so that it is aligned with the normal direction of the curved section of the steel pipe when the tip of the welding torch welds the curved section of the steel pipe, and controls the orientation of the welding torch so that it is perpendicular to the second straight section of the steel pipe when the tip of the welding torch welds a second straight section of the steel pipe from the end position of the curved section of the steel pipe. [Prior art documents] [Patent documents]

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

[0008] In the techniques described in 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 "robot movement speed") is controlled to keep the welding speed constant. However, more precise control of the robot movement speed is not performed, taking 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, with the welding direction being the forward direction. In other words, the factor for maintaining a constant welding speed must take into account not only the robot movement speed but also the movement of the torch as it moves forward and backward. In other words, the robot movement speed must be controlled taking into account the forward and backward movement of the torch angle. In particular, the range in which the forward and backward movement of the torch angle changes is the area around the boundary between the range in which only the guide rail or the workpiece has a curved portion and the range in which both the guide rail and the workpiece have curved portions. If the robot movement speed is not controlled taking the torch angle movement into account, the deposition amount around the boundary will change, resulting in poor bead appearance, such as a convex or concave bead appearance. Therefore, to achieve a good bead appearance, it is necessary to control the robot movement speed around the boundary in accordance with the torch angle control.

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

[0011] The present invention comprises the following configurations.

[0012] [1] A method for controlling a welding robot using a welding system including a guide rail installed 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, 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 step of setting a control condition for each of the regions determined in the region determining step, In the step of setting the control condition, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the step of determining the torch target position, the torch target position is determined on the curved surface portion of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the step of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, a control method for a welding robot, characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near the position WCs1 and the position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each of the torch target positions.

[0013] [2] A welding control device that installs a guide rail for a workpiece having a corner and controls a welding robot that moves on the guide rail to arc-weld the workpiece, a welding condition setting unit that sets welding conditions at a predetermined torch target position, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A welding control device characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near position WCs1 and near position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each torch target position.

[0014] [3] A welding system including a guide rail installed for a workpiece having a corner, a welding robot that moves on the guide rail and arc-welds 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A welding system characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near position WCs1 and near position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each torch target position.

[0015] [4] A control program for a welding robot used in a welding control device that installs a guide rail for a workpiece having a corner 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The control program is configured to cause the welding control device to: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A control program for a welding robot, characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near the position WCs1 and the position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each of the torch target positions. [Effects of the Invention]

[0016] According to the welding robot control method, welding control device, welding system, 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 corner of the workpiece and the curved portion of the guide rail are not concentric. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a welding system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic side view of the portable welding robot. [Figure 3] FIG. 3 is a perspective view of a portable welding robot. [Figure 4] FIG. 4 is a conceptual diagram showing an approximate linear movement mechanism. [Figure 5] FIG. 5 is a perspective view of the portable welding robot attached to a workpiece. [Figure 6] FIG. 6 is a diagram for simply explaining the positional relationship between the workpiece and the guide rail in the quarter corner area. [Figure 7] FIG. 7 is a schematic diagram for explaining the positional relationship between the guide rail and the quarter corner area of ​​the workpiece for each type. [Figure 8] FIG. 8 is a diagram for explaining the positional relationship between the guide rail and the quarter corner area of ​​the workpiece in the case of Type C. [Figure 9] FIG. 9 is a diagram for explaining the positional relationship between the guide rail and the quarter corner area of ​​the workpiece in the case of Type B. [Figure 10] FIG. 10 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. [Figure 11] FIG. 11 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. [Figure 12] FIG. 12 is a diagram for explaining the positional relationship between the guide rail and the quarter corner area of ​​the workpiece. [Figure 13] FIG. 13 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. [Figure 14] FIG. 14 is a diagram for explaining the positional relationship between the guide rail and the quarter corner area of ​​the workpiece. [Figure 15] FIG. 15 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. [Figure 16] FIG. 16 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. DETAILED DESCRIPTION OF THE INVENTION

[0018] A welding robot control method, a welding control device, a welding system, and a welding robot control program according to an embodiment of the present invention will be described below with reference to the drawings. Note that this embodiment is an example of a case where a portable welding robot is used. The present invention is not limited to the configuration of this embodiment.

[0019] Note that unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description 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.

[0020] 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. Furthermore, 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.

[0021] <Welding system configuration> 1 is a schematic diagram showing the 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.

[0022] [Control device] Control device 600, which corresponds to the control device of the present disclosure, is connected to portable welding robot 100 via robot control cable 610 and to welding power source 400 via power supply control cable 620. Control device 600 has teaching data that sets the operation pattern of portable welding robot 100, the welding start position, the welding end position, control conditions for controlling portable welding robot 100 to satisfy the welding conditions described below, welding conditions at predetermined torch target positions, etc., a database (hereinafter also referred to as "DB") that defines welding conditions based on groove shape information, and a data storage unit 601 that stores information such as guide rail information and workpiece information. Control device 600 sends commands to portable welding robot 100 and welding power source 400 based on this teaching data to control the operation and welding conditions of portable welding robot 100. Control device 600 may have a memory, and data storage unit 601 may be included in the memory. Note that the memory corresponds to a storage device.

[0023] The control device 600 has a control unit 604. The control unit 604 includes a calculation unit 602 and a setting unit 603.

[0024] 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 for each axis of the welding robot. The control condition calculation unit 602b calculates control conditions for control to achieve the conditions set by the welding condition setting unit 603b. The control conditions will be described later. As will be described later, the control amount calculated by the control condition calculation unit 602b may be a correction amount for each axis of the portable welding robot 100 or may be the corrected condition.

[0025] The setting unit 603 includes a torch position setting unit 603a that sets a torch target position based on guide rail information and workpiece information (described later), a welding condition setting unit 603b that (a) acquires and sets welding conditions based on the groove shape information and the DB, or (b) corrects and sets welding conditions from the teaching data based on the groove shape information and the DB, and a control condition setting unit 603c that sets control conditions based on the control amount of each axis of the welding robot. Note that the control unit 604 may further include functional blocks that realize functions other than those described above. The control unit 604 may be equipped with a processor and performs various information processing in the control device 600. The welding condition setting unit 603b sets welding conditions at a predetermined torch target position.

[0026] 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, thereby controlling the portable welding robot 100. The control program has various functions related to the control of the portable welding robot 100.

[0027] Further, a controller (not shown) for teaching, manual operation of the portable welding robot 100, and the like is connected to the control device 600. However, this is not limited to this, and the controller for manual operation and teaching and the control device 600, which is a controller having other control functions, may be integrated, or the control device 600 may be included in the portable welding robot 100. Furthermore, 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. Note that, from the viewpoint of usability at a welding site, it is preferable to separate the controller into two: a controller for teaching, manual operation of the portable welding robot 100, and the control device 600, which is a controller having other control functions.

[0028] [Welding power source] Welding power source 400 generates an arc between welding wire 211, which is a consumable electrode, and workpiece Wo by supplying power to welding wire 211 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 then sent from wire feeder 300 to welding torch 200 via conduit tube 420.

[0029] 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 welding power source 400 is supplied to welding wire 211 via a contact tip at the front end of welding torch 200. The welding current used during welding may be DC or AC, and its waveform is not particularly important. Therefore, the current may be a pulse such as a square wave or a triangular wave.

[0030] 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 when welding is performed with reverse polarity; 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.

[0031] [Shielding gas supply source] Shielding gas supply source 500 is composed of a container filled with shielding gas, a valve, and other auxiliary components. Shielding gas is sent from shielding gas supply source 500 to feeder 300 via gas tube 510. The shielding gas sent to feeder 300 is sent to welding torch 200 via conduit tube 420. The shielding gas sent to welding torch 200 flows through welding torch 200, is guided to nozzle 210, and is ejected from the tip side of welding torch 200. The shielding gas used in this embodiment may be, for example, argon (Ar), carbon dioxide (CO2), or a mixture thereof.

[0032] [Feeding device] The feeder 300 pays out the welding wire 211 and feeds it to the welding torch 200. There are no particular limitations on the welding wire 211 fed by the feeder 300, and for example, a solid wire or a flux-cored wire may be used. There are no particular limitations on the diameter of the welding wire, but in this embodiment, the preferred diameter is an upper limit of 1.6 mm and a lower limit of 0.9 mm.

[0033] 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 disposed inside the tube, and a flow path for shielding gas formed therein. However, conduit tube 420 is not limited to this, and for example, a power supply cable and a hose for supplying shielding gas bundled together around a protective tube for feeding welding wire 211 to welding torch 200 can also be used. Also, for example, the tubes for feeding welding wire 211 and shielding gas and the power cable can be installed separately.

[0034] [Portable welding robot] 2 and 3, portable welding robot 100 includes a guide rail 120, a robot body 110 that is installed on guide rail 120 and moves along guide rail 120, and a torch connection unit 130 that is placed on robot body 110. Robot body 110 is mainly composed of a main body 112 that is installed on guide rail 120, a fixed arm unit 114 that is attached to main body 112, and a welding torch rotation drive unit 116 that is attached to fixed arm unit 114 so that it can rotate in the direction of arrow R1.

[0035] Fig. 4 is a conceptual diagram showing approximate linear movement mechanism 180. As shown in Fig. 4, torch connector 130 is attached to welding torch rotation drive unit 116 via sliding table 169 and crank 170 in a state where it can rotate in the direction of arrow R2. Also, as shown in Fig. 3, torch connector 130 is provided with torch clamp 132 and torch clamp 134 that secure welding torch 200. On the side opposite to the side where welding torch 200 is attached, main body 112 is provided with cable clamp 150 that supports conduit tube 420 that connects feeding device 300 and welding torch 200.

[0036] The main body 112 of the robot main body 110 includes an X-axis movement 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 drawing 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 movement mechanism 182 that moves the fixed arm 114 relative to the main body 112 via a 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 movement 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, based on the position of the robot, the welding progress direction is defined as the X-axis, the groove width direction is defined as the Y-axis, and the groove depth direction is defined as the Z-axis. XYZ coordinates are defined as robot coordinates, and are distinguished from world coordinates (workpiece coordinates), which are defined as XwYwZw coordinates (described later).

[0037] Approximate linear movement mechanism 180 is made up of sliding table 169 to which torch connecting part 130 is attached, crank 170, and welding torch rotation drive part 116. Specifically, crank 170 is fixed to rotation shaft 168 of a motor (not shown) that is fixed to welding torch rotation drive part 116, and the tip of crank 170 is connected to one end of sliding table 169 by connecting pin 171. In addition, sliding table 169 has a long groove 169a in the middle part, and fixing pin 172 fixed to welding torch rotation drive part 116 is slidably fitted into long groove 169a.

[0038] As a result, when crank 170 is rotated around rotation shaft 168 by a motor (not shown), sliding table 169 rotates around 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 connecting part 130 to which welding torch 200 is attached rotates the tip of welding wire 211 at an 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. R2 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). In this embodiment, the mechanisms for movement 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 simply described as the "X-axis direction." In addition, the tip position of the welding wire 211 is synonymous with the target position during welding, and may therefore be referred to as the welding target position, torch position, etc.

[0039] 2, welding torch rotation drive unit 116 is rotatably attached to fixed arm unit 114, and may be adjusted to an optimum angle in advance and fixed, or a mechanism may be provided that rotates in the direction of arrow R1 using a motor. The direction of arrow R1 is the direction of rotation around a center line extending in the X-axis direction.

[0040] As described above, the robot main body 110 can move the welding torch 200, which is its tip, in three directions, namely, the X-axis direction, the Y-axis direction, and the Z-axis direction, with five degrees of freedom, namely, 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 main body 110 is not limited to this, and may be movable with any number of degrees of freedom depending on the application. With this configuration, the tip of the welding wire 211 of the welding torch 200 attached to the torch connecting unit 130 can be directed in any direction. That is, the robot main body 110 can be driven on the guide rail 120 in the X-axis direction. Furthermore, 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. Further, the torch angle can be controlled by tilting the welding torch 200 in the forward or backward direction 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 R2 is explained as a negative value.

[0041] 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 on a polygonal steel pipe, the guide rails 120 are positioned so as to go around the outer periphery of the steel pipe, as will be described later, so the handles 160 on both sides are not provided in the positions shown in Figure 3.

[0042] <Robot system installation status for polygonal steel pipes (workpieces)> 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 extend circumferentially around 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 also provided so as to go around the outer surface of the steel pipe via an attachment member 140. The guide rail 120 in this example has a shape that includes four straight sections 121 and four curved sections 122 connecting the straight sections 121.

[0043] The portable welding robot 100 is mounted on the guide rail 120 with the welding torch 200 facing downward. FIG. 6 is a diagram simply illustrating the positional relationship between the guide rail 120 and the workpiece Wo in a quarter-corner region S (the region indicated by the dashed line in FIG. 5 ) when viewed from directly above. The line on the guide rail indicates the position where the guide rail 120 and the X-axis movement mechanism 181 contact, and the line on the steel pipe indicates the welding position. As shown in FIGS. 5 and 6 , in this embodiment, the workpiece Wo is used as the reference, and the height direction of the workpiece Wo (the up-down direction in FIG. 5 ) is the Zw axis. The welding direction of two opposing straight sections WL (the lower left and upper right in FIG. 5 ) of the four straight sections WL is the Xw axis. The welding direction of the other two opposing straight sections WL (the upper left and lower right in FIG. 5 ) of the four straight sections 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 from the XYZ coordinates.

[0044] The guide rail 120 shown in FIGS. 5 and 6 has a straight section 121 and a curved section 122 that are connected to each other, and boundary points 128s and 128e where the guide route changes at the boundary between the straight section 121 and the curved section 122. The boundary points 128s and 128e of the guide rail 120 include a boundary point 128s on the welding start side and a boundary point 128e on the welding end side for each curved section 122 of the guide rail 120. Furthermore, the workpiece Wo has a straight section WL and a corner (curved section) WC that are connected to each other, and boundary points WCs and WCe between the straight section WL and the corner WC. The boundary points WCs and WCe of the workpiece Wo include a boundary point WCs on the welding start side and a boundary point WCe on the welding end side for each corner WC of the workpiece Wo. Furthermore, the curved section 122 of the guide rail has a center position CL, and the corner WC of the workpiece Wo has a center position Cw. Furthermore, at least one arbitrary position WCsn (n is an integer) is provided between the central position Cw and the start position (boundary point WCs in FIG. 6) when the guide rail 120 and the workpiece Wo all form curved surfaces, and at least one arbitrary position WCen (n is an integer) is provided between the central position Cw and the end position (boundary point WCe in FIG. 6) when the guide rail 120 and the workpiece Wo all form curved surfaces. In FIG. 6, as an example, WCs1 and WCe1 are provided at intermediate positions between the central position Cw and boundary point WCs and between the central position Cw and boundary point WCe.

[0045] Furthermore, the distance between boundary point 128e and boundary point WCe in the Xw-axis direction is defined as d1, and the distance between boundary point 128s and boundary point WCs in the Yw-axis direction is defined as d2. Distances d1 and d2 refer to the distances in the range where either one of the guide rail 120 or the 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 the curved portion 122 of the 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.

[0046] In addition, when the guide rail information and workpiece information described later have coordinate data with an arbitrary position on the center side of the workpiece Wo as the origin, and 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 B When the coordinates of are (Xw2, Yw2), the distance d1 and the distance d2 are B Position of the center of curvature O A 1. The distance d1 is calculated as Xw2-Xw1, and the distance d2 is calculated as 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 concentric circles, and when the values ​​are other than 0, it can be determined that they are located on non-concentric circles. 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 within 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 121 and the workpiece Wo is the corner portion (curved portion) WC within the range of d1 and d2, so it can be determined whether it is Type B (described later) or Type C based on the positive or negative values ​​of d1 and d2.

[0047] 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. The following explanation will be made based on FIGS. 7(a) to 7(c). FIGS. 7(a) to 7(c) are schematic diagrams each explaining the positional relationship between the workpiece Wo and the guide rail in the quarter corner area for each type, with FIG. 7(a) showing the positional relationship for Type A, FIG. 7(b) showing the positional relationship for Type B, and FIG. 7(c) showing the positional relationship for Type C. FIG. 8 is a diagram explaining the positional relationship between the workpiece Wo and the guide rail 120 in the quarter corner area when FIG. 5 is viewed from directly above in the case of Type C.

[0048] <Type A> Type A shown in FIG. 7(a) has a center of curvature O, which is the center position of the arc of the curved portion 122 of the guide rail 120. Aand the center of curvature O, which is the center position of the arc at the corner of the workpiece. 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 distances d1 and d2 do not exist (distance d1 = 0, distance d2 = 0).

[0049] <Type B> Type B shown in FIG. 7(b) has a center of curvature O, which is the center position of the arc of the curved portion 122 of the guide rail 120. 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 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 curved portion 122 and the workpiece Wo is at the straight portion WL.

[0050] <Type C> In the type C shown in FIG. 7(c) and FIG. 8, 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 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 A8)。In the range of d1 and d2, the guide rail 120 is a straight section WL, and the workpiece Wo is a corner section WC. In addition, between the center position Cw and the start position when the guide rail 120 and the workpiece Wo are all curved surfaces (the torch position when the robot is located at 128s in FIG. 8), at least one arbitrary position WCsn (n is an integer) is set, and between the center position Cw and the end position when the guide rail 120 and the workpiece Wo are all curved surfaces (the torch position when the robot is located at 128e in FIG. 8), at least one arbitrary position WCen (n is an integer) is set. In FIG. 8, as an example, WCs1 and WCe1 are set at intermediate positions between the torch positions when the robot is located at the center position Cw and 128s and the torch positions when the robot is located at the center position Cw and 128e.

[0051] Since the control process differs for each of Types A to C, it is necessary to determine which of Types A to C the workpiece Wo falls under based on the guide rail information and the workpiece information. Therefore, first, based on the guide rail information and the workpiece information, it is determined whether the curved portion 122 of the guide rail 120 and the corner portion WC of the workpiece Wo are located concentrically or non-concentrically. If they are located concentrically, the workpiece Wo is determined to be Type A, and if they are located non-concentrically, the workpiece Wo is determined to be Type B or Type C. Furthermore, if the workpiece Wo and the guide rail 120 are located non-concentrically, the workpiece Wo is determined to be Type B if only the guide rail 120 is a curved portion in Regions I and III. If only the workpiece Wo is a curved portion in Regions I and III, the workpiece Wo is determined to be Type C. The regions will be described later.

[0052] When determining whether the curved portion 122 of the guide rail 120 and the corner 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 area I and the area III calculated based on the guide rail information and the workpiece information, or the distances d2 and d1 in the welding direction of the area I and the area III set in advance. That is, if d1 and d2 are 0 (d1 = d2 = 0), the type may be determined to be Type A, and in other cases, the type may be determined to be either Type B or C. In addition, the "center of curvature O" may be determined to be 0. 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 to be Type B, and if the distances d1 and d2 are negative values, the object may be determined to be Type C.

[0053] Hereinafter, the control process for welding the corners WC of the non-concentric type B and type C workpieces Wo will be described.

[0054] <First embodiment: Type B control process> [Guide rail information, workpiece information settings] The guide rail information and workpiece information may be input in advance as CAD data or the like into the data storage unit 601 of the control device 600, 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 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 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 (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, WCsn, and WCen. In this embodiment, the guide rail information and the workpiece information require at least the shape information of the groove 10 including the thickness of the workpiece Wo, the information on the distances d1 and d2, and the information on the distance R. It is preferable that the information on the thickness of the workpiece Wo and the shape information of the groove 10 are input into 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.

[0055] Here, in this embodiment, the reason why the thickness of the workpiece Wo is required as workpiece information is because the types of polygonal steel pipes that are commonly used are limited. Specifically, examples include press-formed polygonal steel pipes for building structures (BCP) and roll-formed polygonal steel pipes for building structures (BCR). 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 the center of curvature O of the corner 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 curvature radius RB or the curvature center O of the corner WC of the work Wo can be obtained. B The position information can be obtained in another way.

[0056] In this embodiment, sensing is performed by applying a voltage between the workpiece Wo and the welding wire 211, and using a voltage drop phenomenon that occurs when the welding wire 211 comes into contact with the workpiece Wo, a touch sensor is used as the detection means to sense the surface of the groove 10, etc. 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 also be used, but it is preferable to use the touch sensor of this embodiment in view of the simplicity of the device configuration.

[0057] In the sensing step before the start of welding, an arbitrary sensing position is identified using the touch sensor described above, and touch sensing of the groove shape, plate surface, etc. is performed at the identified sensing position to extract groove shape information, information on distance R by touching the plate surface and measuring the distance. Groove shape detection is performed by moving the tip of the welding wire 211 around the groove 10 to determine the torch position of the workpiece Wo. In other words, by identifying the position when the tip of the welding wire 211 touches the workpiece Wo, the shape information of the groove 10 described above and the plate thickness of the workpiece Wo can be identified. Note that in the sensing step before the start of welding, touch sensing may be performed using a sensing chip dedicated to sensing.

[0058] The sensing position is not particularly important, but in Types B and C, the control conditions described below have different control formulas for at least Region IV (hereinafter sometimes referred to as "A4") shown in Figure 9, where the guide rail 120 and the workpiece Wo are both straight, Region I (hereinafter sometimes referred to as "A1"), where either the guide rail 120 or the workpiece Wo has a curved portion on the welding start position side, Region II (hereinafter sometimes referred to as "A2"), where both the guide rail 120 and the workpiece Wo have a curved portion, and Region III (hereinafter sometimes referred to as "A3"), where either the guide rail 120 or the workpiece Wo has a curved portion on the welding end position side. Therefore, it is preferable to identify the torch position (welding position) that is the boundary between these Regions I to IV by sensing and obtain information such as groove shape information or distance R. In the present invention, groove shape information may be acquired by sensing for at least one of the following positions: any position in region IV (A4), the start position of the curved surface of the guide rail 120, and the center position of region II (A2). In this embodiment, groove shape information is acquired by sensing for three points: the welding start position located within region IV (A4), the start position of the curved surface of the guide rail 120, and the center position of region II (A2). By calculating groove shape information for at least these three points, welding conditions can be set with high accuracy even if there are disturbances such as misalignment of the guide rail. In this embodiment, sensing is also performed on the start and end portions of the curved surface of the workpiece Wo, and information on the distance R is acquired by sensing.That is, it is preferable to set at least the following sensing positions: torch target position P1 when the robot is positioned 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 positioned at boundary point WCs on the welding start side of corner WC of workpiece Wo; torch target position P3 when the torch is positioned at center position Cw of corner WC of workpiece Wo; torch target position P4 when the torch is positioned at boundary point WCe on the welding end side of corner WC of workpiece Wo; and torch target position P5 when the robot is positioned at boundary point 128e, which is the end position of curved portion 122 of guide rail 120. By setting the sensing positions in this manner, the region is determined. Note that hereinafter, torch target positions P1 to P5 may also be referred to as sensing positions P1 to P5. Furthermore, the robot positions on guide rail 120 when at torch target positions P1 to P5 are AP1 to AP5, respectively.

[0059] After the sensing step, a groove shape information calculation step is performed in which a 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. Examples of 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 as set values ​​to the data holding unit 601. 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 as set values ​​to the data holding unit 601. Note that 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.

[0060] [Welding condition settings] Next, based on the data of the groove shape information input as setting values ​​to the data storage unit 601 and the DB, the set values ​​of the welding conditions in the teaching program data are corrected or set. In this embodiment, for example, the welding current, arc voltage, welding speed, weaving conditions, welding target position, and tip-base metal distance (hereinafter also referred to as "extension length") are set or corrected. Also, the target torch angle relative to the workpiece Wo may be set or corrected. Note that "setting or correcting" means setting a set value if it has not yet been set, or correcting a set value if it has already been set. Here, specific examples of weaving conditions include the swing width and weaving period.

[0061] In this embodiment, since multi-layer welding is common, it is a basic premise that the layer height per layer is constant in straight and curved sections. Therefore, it is preferable to perform layer design based on groove shape information and set or correct welding conditions based on the calculated layer design information. Here, the layer design information includes the number of layers, the number of passes, and the layer height (≒ height per pass), but the welding conditions are determined based on at least the calculated layer height value. For example, if sensing reveals a larger gap at the welding end position than at the welding start position, the gap width widens as welding progresses, so the deposition amount must be increased to maintain a constant layer height. In this case, welding conditions related to the deposition amount include the wire feed speed and welding speed, and these welding conditions can be set or corrected based on the groove shape information and the layer 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 kept constant in both straight and curved sections, and the deposition amount can be controlled to keep the build-up height constant by changing the welding speed conditions. Note that, since welding power sources generally associate an optimal welding current value with each feed speed, it is possible to set either the wire feed speed setting value or the welding current setting value.

[0062] Although the torch target position for setting or correcting welding conditions is not particularly limited, it is preferable to set the torch target position at least at the same position as the sensing position because the welding conditions are determined based on groove shape information. Since the torch target position is the position where the welding conditions are set or corrected, it is generally also referred to as a teaching point. In this embodiment, since the sensing positions P1 to P5 are the same positions, they may hereinafter be referred to as torch target positions P1 to P5. If the welding conditions between the torch target positions are different, the conditions may be varied in a linear, curved, or step-like manner. For example, if the welding speed at torch target position P1 is set to 30 cm / min and the welding speed at torch target position P2 is set to 35 cm / min, the welding speed condition between P1 and P2 will vary in a manner that depends on the robot travel distance, time, etc.

[0063] [Control conditions for control] The control conditions are set by calculating the control conditions in the control condition calculation unit 602b or by determining the control conditions based on a predetermined database. 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-concentric welding, the "welding speed = robot movement speed" does not necessarily hold depending on 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 are adjusted so that the set welding conditions can be maintained. R2 It is necessary to calculate the control conditions such as the above and set them for each target torch position.

[0064] 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 movement speed (condition of the X-axis movement 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 movement mechanism 182). The control condition related to the extension length and the target position in the groove width direction is the groove depth direction position (condition of the Z-axis movement mechanism 183). The control condition related to the target torch angle is the torch angle Θ R2(Conditions for the approximate linear movement mechanism 180 (R2 direction rotation mechanism)). The control conditions for the target torch attitude angle are the torch attitude angle Θ R1 (Conditions for welding torch rotation drive unit 116 (R1 direction rotation mechanism)).

[0065] Here, unless otherwise specified, in the present invention, when the term "target torch angle" is used, it refers to a welding condition that indicates the torch angle relative to the welding surface, and when the term "torch angle" is simply used, it refers to the torch angle Θ of the approximate linear movement mechanism 180 (R2 direction rotation mechanism). R2 When referred to as a "target torch attitude angle," this refers to a welding condition that indicates the torch attitude angle relative to the welding surface, and when simply referred to as a "torch attitude angle," this refers to 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 tilt in the X-axis direction, which is the direction of the weld line, and the torch posture angle is the angle of tilt in the Y-axis direction, which is perpendicular to the direction of the weld line.

[0066] In addition, the groove width direction position, groove depth direction position, torch angle Θ R2 , torch attitude angle Θ R1 The control condition of 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 of the torch angle is the torch angle Θ as will be described later. R2 The torch angle correction amount θt is used as a control condition, with the torch angle being 0° as the reference, and the groove depth direction position is the groove depth direction correction amount, which is the amount of movement with a predetermined extension length as the reference (0 position). Note that each reference value may be based on the conditions in region IV (A4).

[0067] In the present invention, it is necessary to control at least the control conditions of the torch angle and the robot movement speed at appropriate timing in each region. Below, we will explain the torch angle correction amount θt for each torch target position calculated based on the welding robot position An on the guide rail, the method for calculating the robot movement speed, and the control process of the torch angle and the robot movement speed between each torch target position.

[0068] [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 using Figure 9. Figure 9 is a diagram illustrating the positional relationship between the guide rail 120 and the quarter corner area of ​​the workpiece Wo when viewed from directly above in the case of Type B in Figure 5. The torch angle correction amount θt is calculated for each of areas I to IV based on the robot position angle θ and the workpiece angle θ1, which will be described later.

[0069] The welding robot is positioned at the center of curvature O A Therefore, when the current position of the welding robot is An, the robot position angle θ is A and the current position An of the welding robot. A -An) and the Yw-axis direction (O A and the line segment connecting AP1) and the angle θ.

[0070] FIG. 9 shows an example where the torch target angle is 0° (perpendicular to the welding surface), and the robot position on the guide rail 120 at torch target position P1 is position AP1 in FIG. 9. The robot position on the guide rail 120 at torch target position P2 is AP2 in FIG. 9. The robot position on the guide rail 120 at torch target position P3 is AP3 in FIG. 9. The robot position on the guide rail 120 at torch target position P4 is AP4 in FIG. 9. The robot position on the guide rail 120 at torch target position P5 is AP5 in FIG. 9. Note that the robot positions in FIG. 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.

[0071] In addition, since the welding robot moves in the direction from AP1 to AP5, the robot position angle θ is A -An and Xw axis directions (O Aand P1). In other words, when the current robot position An is at, for example, AP1, the robot position angle θ can be shown as 0° (the start position of the curved section 122), when it is at AP3 it can be shown as 45° (the center position of the curved section 122), and when it is at AP5 it can be shown as 90° (the end position of the curved section 122). Naturally, when the welding direction is opposite to that in FIG. 9, the angle formed by the line segment LAn (line segment OA-An) and the XYw axis direction becomes the robot position angle θ.

[0072] Here, 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, so the robot position angle θ can be converted into the moving distance D (mm) from the starting point AP1.

[0073] (Work angle θ1) The work angle θ1 is the center of curvature O B and the current position An of the welding robot. B 9, the welding direction of the welding robot is the direction of movement from AP1 to AP5, so the work angle θ1 is the angle formed by the line segment LBn (line segment O B -An) and Xw axis direction (O B and the line segment connecting P2.

[0074] (Calculation of torch angle correction amount θt in area I) In region I (A1), when the torch target angle θs is 0° (perpendicular to the welding surface), the torch angle correction amount θt may be set to equal the robot position angle θ due to the relationship of alternate angles. In this embodiment, the torch target positions in region I are P1 and P2, so the robot position angle torch angle correction amount θt as a control condition for the P1 and P2 positions is set to the angle (0)° formed by the line segment connecting the center of curvature OA and AP1 with the Xw axis direction, and the angle (0)° formed by the line segment connecting the center of curvature OA and AP1 with the Xw axis direction. A The angle (sin -1 (d2 / RA)×180 / π)°, and the torch angle Θ between P1 and P2 R22is set as the control condition.

[0075] 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 R2 may 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.

[0076] (Calculation of torch angle correction amount θt in region II) In region II (A2), the torch angle correction amount θt is calculated from the difference between the robot position angle θ and the workpiece angle θ1 (θt = θ - θ1). Specifically, it can be converted as tanθt = tan(θ - θ1) = (tanθ - tanθ1) / (1 + tanθ × tanθ1). Therefore, the torch angle correction amount θt is expressed as in the following formula (1). θt=tan -1 ((tanθ-tanθ1) / (1+tanθ×tanθ1))...(1)

[0077] Here, when the welding robot position An is expressed in the XwYw coordinate system, the welding robot position An(Xw, Yw) is (RAcosθ, RAsinθ), and therefore is expressed by the following formula (2). tanθ1=(RAsinθ-d2) / (RAcosθ-d1)...(2)

[0078] Substituting formula (2) into formula (1) gives the following formula (3), from which the torch angle correction amount θt for region II (A2) 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°.

[0079] In this embodiment, the torch target positions in area II (A2) are P2 to P4.

[0080] In the region III (A3), the torch angle correction amount θt is calculated as θt=θ-90°. In this embodiment, the torch target positions in the region III (A3) are P4 and P5, so the robot position angle θ as a control condition for the P4 and P5 positions is calculated as 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)°, the angle (90°) between the line segment connecting the center of curvature OA and AP5 and the Xw axis direction, and the torch angle Θ at positions P4 and P5 R2 is set as the control condition.

[0081] In the region IV (A4), it is not necessary to control the control conditions. Therefore, the control conditions in the region IV (A4) are the reference values. In this embodiment, for example, the torch target angle θs = the torch angle Θ in the region IV (A4) R2 (That is, the torch angle correction amount θt is always 0.) It is also preferable that the torch target angle θs is set to 0°.

[0082] As explained above, torch angle control in regions I to III in Type B results in the torch angle correction amount θt fluctuating as shown in Fig. 10(a). Fig. 10(a) is a graph showing the torch angle correction amount θt versus the robot position angle θ, and Fig. 10(b) is a graph showing the robot movement speed versus the robot position when the change in speed 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).

[0083] That is, as shown in FIG. 10(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 (A1) (torch target position P1) to approximately the end position of area I (A1) (torch target position P2) or near the end position of area I (A1). Control (B): 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 area II (A2) (torch target position P2) to approximately the center position of area II (A2) (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 area II (A2) (torch target position P3) to approximately the end position of area II (A2) (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 area III (A3) (torch target position P4) to approximately the end position of area III (A3) (torch target position P5).

[0084] [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.

[0085] 10(b), a conventional robot movement speed control technique that does not take into account the speed change in the X-axis direction caused 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 equation (4). Vn=RA / Ln×V0 …(4)

[0086] In this embodiment, since the torch target positions are P1 to P5, n is an integer between 1 and 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 later) (Ln=RA-Rn).

[0087] Furthermore, "V0" is the robot movement speed setting value in region IV (A4), and since the robot movement speed setting value and the welding speed setting value in region IV (A4) are equal, in this embodiment, the robot movement speed setting value in region IV (A4) is set as the reference robot movement speed setting value V0.

[0088] The robot movement speed on the curved surface at this time is as shown in Figure 10(b). Specifically, in region IV (A4) before reaching torch target position P1, the robot movement speed is V0. When torch target position P1 is reached, the robot movement speed instantaneously accelerates to V1 = RA / L1 × V0, and then gradually decelerates until torch target position P3 is reached. When torch target position P3 is reached, the robot movement speed gradually accelerates to V5 = RA / L5 × V0 from torch target position P3 to P5. When torch target position P5 is reached, the robot movement speed instantaneously decelerates to V0.

[0089] However, as the object of the present invention, when the torch angle is set as a control condition, the torch angle Θ R2 As the position of the robot changes, welding torch 200 moves in the X-axis direction. Therefore, it is necessary to control the robot movement speed in each of regions I to IV, taking into account the range of movement in the X-axis direction by approximate linear movement mechanism 180.

[0090] In the present invention, in region II (A2), at least during the period (A2s) between the center position Cw and the welding start side of the center position Cw, one position (WCs1) where the robot movement speed is abruptly changed is provided, and at least during the period (A2e) between the center position Cw and the welding end side of the center position Cw, one position (WCe1) where the robot movement speed is abruptly accelerated or decelerated is provided. In this manner, by changing the robot movement speed stepwise in region II (A2), a good bead appearance can be obtained. Note that the number of positions provided during the period A2s or A2e is not limited to one, and multiple positions may be provided, and the positions may also be arbitrary. In this embodiment, one position is provided at the center between A2s and A2e. "Steep" refers to a steep gradient of change. For example, in FIG. 10(b), the horizontal axis represents the robot position and the vertical axis represents the robot movement speed. "Steep" may mean that the absolute value of the gradient given by the displacement along the vertical axis / the displacement along the horizontal axis is greater than a predetermined threshold. In other words, "steep" may mean that the moving speed changes in an almost step-like manner, such as when the moving speed suddenly increases or decreases from a certain moment.

[0091] Furthermore, in this embodiment, the robot's movement speed is not particularly limited in the section from the start position of region II (A2) to WCs1 (section a), the section from after the robot's movement speed changes sharply at WCs1 to Cw (section b), the section from Cw to WCe1 (section c), and the section from after the robot's movement speed changes sharply at WCs1 to the end position of region II (A2) (section d). For example, the robot may be controlled at a constant speed in these sections, or it may be accelerated or decelerated. Furthermore, a combination of constant speed, acceleration, and deceleration may be used within the same section. In this way, the change in the robot's movement speed between each point is not particularly limited and may be changed according to the situation.

[0092] Although there is no particular restriction on the control of region I (A1) and region III (A3), it is preferable to simultaneously control region I (A1) and region III (A3) in consideration of the bead appearance at the boundary between region I (A1) and region II (A2) or at the boundary between region II (A2) and region III (A3). In the present invention, the preferred control of region I (A1) and region III (A3) will be described later.

[0093] As described above, by controlling the robot movement speed in region II (A2), it is possible to improve the bead appearance all around the workpiece.

[0094] Next, a control process will be described with reference to FIG. 11 as a preferred example of the present invention. FIG. 11 is a graph showing an example of control of the torch angle correction amount and robot movement speed. In the graph of the robot movement speed in FIG. 11, the curved dashed line in region II (A2) represents conventional control of the robot movement speed. Note that the torch angle is controlled in the same way as in the conventional method.

[0095] Based on the robot movement speed control in FIG. 11, the specific control process will be explained as follows (1) to (13). (1) The robot movement speed V0 set in area IV (A4) is maintained until the torch target position P1 (robot position AP1) is reached. (2) When the torch reaches the target position P1, it instantly decelerates. (3) After deceleration, a constant speed is maintained during region I (A1) (until the torch reaches target position P2). (4) When the torch reaches the target position P2, it accelerates sharply. The target speed of acceleration is set to be higher than in the past (accelerating to a target speed higher than the curved dashed line in FIG. 11). (5) After accelerating, when the target speed value is reached, the vehicle gradually decelerates to the position of WCs1. (6) When WCs1 is reached, the robot is rapidly decelerated to a predetermined target speed. The target speed may be decelerated to a conventional speed (the same speed as the curved dashed line in FIG. 11). In this embodiment, the robot movement speed in section a from P2 to WCs1 is reset to a value obtained by multiplying the initial setting value (the robot movement speed setting value calculated by the conventional method) by a predetermined constant only for section a. (7) After steep deceleration at WCs1, gradually decelerate to the torch target position P3 (Cw). (8) After reaching the torch target position P3 (Cw), gradually accelerate to WCe1 (9) When WCe1 is reached, the vehicle is rapidly accelerated to a predetermined target speed. The target speed is set to be higher than in the past (the vehicle is accelerated to a target speed higher than the curved dashed line in FIG. 11). (10) After a steep deceleration at WCe1, the robot gradually accelerates to the torch target position P4. Note that the robot movement speed in section d, from the time of the steep deceleration at WCe1 until the time of reaching P4, is reset to a value obtained by multiplying the initial setting value by a predetermined constant, just like section a. (11) When it reaches P4, it decelerates sharply. (12) After deceleration, a constant speed is maintained until the torch reaches the target position P5. (13) When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 set in area IV (A4).

[0096] As described above in (6) and (10), the control method of changing the set value of the robot movement speed by multiplying the initial setting of the robot movement speed by a constant only in a certain section is merely an example, and there is no particular restriction on the control method as long as acceleration and deceleration can be performed as shown in Figure 11.

[0097] FIG. 12 is a diagram illustrating the positional relationship between the guide rail 120 and the quarter corner area of ​​the workpiece Wo when viewed from directly above in FIG. 5 in the case of Type B. FIG. 13 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. In the present invention, in region II (A2), two or more positions at which the robot movement speed is abruptly changed may be provided between the center position Cw and the period (A2s) on the welding start side from the center position Cw. Similarly, two or more positions at which the robot movement speed is abruptly accelerated or decelerated may be provided between the center position Cw and the period (A2e) on the welding end side from the center position Cw. FIGS. 12 and 13 are diagrams illustrating an example in which two or more positions at which the robot movement speed is abruptly accelerated or decelerated are provided. In the diagrams, two points, WCs1 and WCs2, are provided between the center position Cw and the period on the welding start side from the center position Cw. In addition, two points WCe1 and WCe2 are provided between the center position Cw and the period on the welding end side of the center position Cw.

[0098] FIG. 14 is a diagram illustrating the positional relationship between the guide rail 120 and the quarter corner area of ​​the workpiece Wo when viewed from directly above in FIG. 5 in the case of Type B. FIG. 15 is a graph showing an example of control of the torch angle correction amount and the robot movement speed. It is preferable to control areas I (A1) and III (A3) as shown in FIGS. 14 and 15. The control process will be explained based on FIGS. 14 and 15. In the graph of the robot movement speed in FIG. 15, the curved dashed line in area II (A2) represents conventional control of the robot movement speed. The torch angle control is conventional.

[0099] Based on the robot movement speed control shown in FIGS. 14 and 15, the specific control process will be explained as follows (1) to (14). (1) The robot movement speed V0 set in area IV (A4) is maintained until the torch target position P1 (robot position AP1) is reached. (2) When the torch reaches the target position P1, it instantly decelerates. (3) After deceleration, 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 AP2), the robot is accelerated instantaneously (at a second gradient) to the set value of the robot movement speed for the torch target position P2. At this time, in this embodiment, the target speed to which the robot is accelerated is the initial setting speed (to a value similar to the robot movement speed at the AP2 position indicated by the black line). (5) When the torch reaches the target position P2, it accelerates sharply. The target speed of acceleration is set to be higher than in the past (accelerating to a target speed higher than the curved dashed line in FIG. 15). (6) After accelerating, when the target speed value is reached, the vehicle gradually decelerates to the position of WCs1. (7) When WCs1 is reached, the robot is rapidly decelerated to a predetermined target speed. The target speed may be decelerated to a conventional speed (the same speed as the curved dashed line in FIG. 15). In this embodiment, the robot movement speed in section a from P2 to WCs1 is reset to a value obtained by multiplying the initial setting value (the robot movement speed setting value calculated by the conventional method) by a predetermined constant only for section a. (8) After the rapid deceleration at WCs1, the torch gradually decelerates to the target position P3 (Cw). (9) After reaching the torch target position P3 (Cw), the torch gradually accelerates to WCe1. (10) When WCe1 is reached, the vehicle is rapidly accelerated to a predetermined target speed. The target speed is set to be higher than in the past (the vehicle is accelerated to a target speed higher than the curved dashed line in FIG. 15). (11) After a steep deceleration at WCe1, the robot gradually accelerates to the torch target position P4. Note that the robot movement speed in section d, from the time of the steep deceleration at WCe1 until the time of reaching P4, is reset to a value obtained by multiplying the initial setting value by a predetermined constant, just like section a. (12) When it reaches P4, it decelerates sharply (at a third slope). (13) After instantaneous deceleration, the robot gradually decelerates (at the fourth gradient) until it reaches the torch target position P5 (robot position is AP5). (14) When the torch reaches the target position P5, the robot instantaneously accelerates to the robot movement speed V0 set in area IV (A4).

[0100] The specific control method for the region I (A1) or the region III (A3) is not particularly limited as long as it can be controlled as shown in FIGS.

[0101] For example, for area I (A1) or area III (A3) in the case of type B, the following controls (α) to (β) may be performed based on the robot movement speed calculated and set by the control condition calculation unit 602b. Control (α): In the region I (A1), 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 (A1). Section (B): A control section in which the torch is accelerated at a first gradient within the region I (A1) or to a predetermined set value of the torch target position. Section (C): A control section in which the torch accelerates toward the approximate end position of the region I (A1) at a second gradient or to a predetermined set value of the torch target position. Control (β): In the region III (A3), at least one of the following sections (D) to (E) is controlled: Section (D): A control section in which the rotational speed is decelerated at a third gradient at approximately the start position of the region III (A3) or to a preset value of the torch target position. Section (E): A control section in which, within the region III (A3), the rotational speed is decelerated at a fourth gradient toward the approximate end position of the region III (A3), or to a preset value of the torch target position.

[0102] <Second embodiment: Type C control process> The control process for Type C shown in FIG. 7(c) is similar to the control process for Type B described above.

[0103] Fig. 16 is a graph showing an example of control of the torch angle correction amount and robot movement speed in the case of Type C. Based on the robot movement speed control of Fig. 16, the specific control process when slowing down the speed will be explained as follows (1) to (13). It is assumed that WCs1 and WCe1 are set to the positions shown in Fig. 8. (1) The robot movement speed V0 set in area IV (A4) is maintained until the torch target position P1 (robot position AP1) is reached. (2) When the torch reaches the target position P1, it accelerates sharply. (3) After a steep acceleration, the robot gradually decelerates to the torch target position P6 (robot position is AP6). (4) Instantaneous deceleration occurs immediately before the torch reaches target position P2 (robot position is AP2). (5) When the torch reaches the target position P2, it gradually accelerates. (6) When it reaches WCs1, it accelerates sharply. (7) Gradually accelerate to the torch target position P3 (robot position is AP3). (8) Gradually decelerate from the torch target position P3 to WCe1. (9) When it reaches WCe1, it decelerates sharply. (10) Gradually decelerate to the torch target position P4 (robot position is AP4). (11) When the torch reaches the target position P4, it accelerates instantaneously. (12) Gradually accelerate to the torch target position P5 (robot position is AP5). (13) When the torch reaches the target position P5, the robot decelerates sharply, and then maintains the robot movement speed V0.

[0104] Next, the specific control process for increasing the speed based on the robot movement speed control in Fig. 16 will be explained as follows (1) to (13). It is assumed that WCs1 and WCe1 are set to the positions shown in Fig. 8. (1) The robot movement speed V0 set in area IV (A4) is maintained until the torch target position P1 (robot position AP1) is reached. (2) When the torch reaches the target position P1, it accelerates sharply. (3) After a steep acceleration, the robot gradually decelerates to the torch target position P6 (robot position is AP6). (4) The robot momentarily decelerates just before reaching the torch target position P2 (robot position AP2). However, the robot movement speed remains higher than when the speed is increased as described above. (5) When the torch reaches the target position P2, it gradually accelerates. (6) When it reaches WCs1, it decelerates sharply. (7) Gradually accelerate to the torch target position P3 (robot position is AP3). (8) Gradually decelerate from the torch target position P3 to WCe1. (9) When it reaches WCe1, it accelerates sharply. (10) Gradually decelerate to the torch target position P4 (robot position is AP4). (11) When the torch reaches the target position P4, it accelerates instantaneously. (12) Gradually accelerate to the torch target position P5 (robot position is AP5). (13) When the torch reaches the target position P5, the robot decelerates sharply, and then maintains the robot movement speed V0.

[0105] In the case of Type C, 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 retreat direction from approximately the start position (torch target position P1) of area I (A1) to approximately the end position (torch target position P2) of area I (A1). Control (B): 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 area II (A2) (torch target position P2) to approximately the center position of area II (A2) (torch target position P3). Control (C): Control is performed to tilt the torch angle in the welding forward direction from approximately the center position of area II (A2) (torch target position P3) to approximately the end position of area II (A2) (torch target position P4). Control (D): 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 area III (A3) (torch target position P4) to approximately the end position of area III (A3) (torch target position P5).

[0106] The specific control method for the region I (A1) or the region III (A3) is not particularly limited as long as it can be controlled as shown in FIG.

[0107] For example, for area I (A1) or area III (A3) in the case of type C, the following controls (γ) to (Δ) may be performed based on the robot movement speed calculated and set by the control condition calculation unit 602b. Control (γ): In the region I (A1), control is performed in at least one of the following sections (F) to (H): Section (F): A control section in which acceleration occurs approximately at the start position of the area I (A1). Section (G): A control section in which the speed is decelerated at a fifth gradient within the region I (A1) or to a predetermined set value of the torch target position. Section (H): A control section in which the rotational speed is decelerated at a sixth gradient toward the approximate end position of the region I (A1) or to a predetermined set value of the torch target position. Control (Δ): In the region III (A3), at least one of the following sections (I) to (J) is controlled: Section (I): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III (A3) or to a preset value of the torch target position. Section (J): A control section in which, within the region III (A3), acceleration is performed at an eighth gradient toward the approximate end position of the region III (A3), or up to a preset value of the torch target position.

[0108] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0109] As described above, the present specification discloses the following:

[0110] [1] A method for controlling a welding robot using a welding system including a guide rail installed 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, 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 step of setting a control condition for each of the regions determined in the region determining step, In the step of setting the control condition, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the step of determining the torch target position, the torch target position is determined on the curved surface portion of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the step of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, a control method for a welding robot, characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near the position WCs1 and the position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each of the torch target positions.

[0111] [2] In the curved surface portion of the workpiece, The section between the boundary position (start side) and the position WCs1 is called section a. The section between the position WCs1 and the position Cw is called section b, The section between the position Cw and the position WCe1 is called section c, The section between the position WCe1 and the boundary position (end side) is called section d. In this case, The change in the moving speed of the welding robot during the section a and the section c is controlled to at least one of a constant speed, acceleration, and deceleration; The change in the moving speed of the welding robot during the section b and the section d is as follows: After the welding robot reaches position WCs1 or WCe1 and the moving speed thereof is suddenly accelerated or decelerated, The control method according to [1], characterized in that the control is performed at at least one of a constant speed, acceleration, and deceleration.

[0112] [3] In the area determination step, the area to be determined is: at least, Area I (A1): Area where either the guide rail or the workpiece has a curved surface on the welding start position side. Area II (A2): Area where both the guide rail and the workpiece are curved surfaces Region III (A3): Region where either the guide rail or the workpiece has a curved surface on the welding end position side. Area IV (A4): Area where both the guide rail and the workpiece are linear The control method according to [2], characterized in that:

[0113] [4] In the step of setting the control conditions, the control conditions include a torch angle correction amount, The control method according to [2], characterized in that the control condition calculation unit calculates a torch angle correction amount based on a calculation formula for each of the regions.

[0114] [5] When the guide rail is a curved surface portion in the region I (A1) and the region III (A3), in the step of setting the control conditions, In the section a, deceleration is performed using one type of gradient or a combination of two or more types of gradients, In the section b, after a steep deceleration, Deceleration at one slope or a combination of two or more slopes, or a constant speed, The section c is Acceleration with one or more gradients, or a constant speed, In the section d, after a steep acceleration, acceleration with one kind of gradient or a combination of two or more kinds of gradients is performed. The control method according to [3], characterized in that the movement speed of the welding robot is set.

[0115] [6] In the step of setting the control conditions, the control conditions include a torch angle correction amount, Based on the torch angle correction amount calculated and set by the control condition calculation unit, Control of tilting the torch angle in the welding forward direction from approximately the start position of area I (A1) to approximately the end position of area I (A1); Controlling the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region II (A2) to approximately the center position of region II (A2); Controlling the torch angle in the welding retreat direction from approximately the center position of the region II (A2) to approximately the end position of the region II (A2); Controlling the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region III (A3) to approximately the end position of region III (A3); The control method according to [5], characterized in that the control conditions are set so as to perform the above.

[0116] [7] When the workpiece has a curved surface in the region I (A1) and the region III (A3), in the step of setting the control conditions, In the section a, acceleration is performed with one type of gradient or a combination of two or more types of gradient, In the section b, after a steep acceleration, one of acceleration with one gradient or a combination of two or more gradients, and a constant speed is performed, In the section c, either one of deceleration with one gradient or a combination of two or more gradients, or a constant speed is performed, In the section d, after a steep deceleration, deceleration is performed with one type of gradient or a combination of two or more types of gradients. The control method according to [3], characterized in that the movement speed of the welding robot is set.

[0117] [8] In the step of setting the control conditions, the control conditions include a torch angle correction amount, Based on the torch angle correction amount calculated and set by the control condition calculation unit, Control of tilting the torch angle in the welding retreat direction from approximately the start position of area I (A1) to approximately the end position of area I (A1); Controlling the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region II (A2) to approximately the center position of region II (A2); Controlling the torch angle in the welding forward direction from approximately the center position of the region II (A2) to approximately the end position of the region II (A2); Controlling the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region III (A3) to approximately the end position of region III (A3); The control method according to [5], characterized in that the control conditions are set so as to perform the above.

[0118] [9] The control method described in [3], characterized in that the following controls (α) to (β) are performed based on the movement speed of the welding robot calculated and set by the control condition calculation unit. Control (α): In the region I (A1), 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 (A1). Section (B): A control section in which the torch is accelerated at a first gradient within the region I (A1) or to a predetermined set value of the torch target position. Section (C): A control section in which the torch accelerates toward the approximate end position of the region I (A1) at a second gradient or to a predetermined set value of the torch target position. Control (β): In the region III (A3), at least one of the following sections (D) to (E) is controlled: Section (D): A control section in which the rotational speed is decelerated at a third gradient at approximately the start position of the region III (A3) or to a preset value of the torch target position. Section (E): A control section in which, within the region III (A3), the speed is decelerated at a fourth gradient toward the approximate end position of the region III (A3) or to a preset value of the torch target position.

[0119]

[10] The control method described in [3], characterized in that the following controls (γ) to (Δ) are performed based on the movement speed of the welding robot calculated and set by the control condition calculation unit. Control (γ): In the region I (A1), control is performed in at least one of the following sections (F) to (H): Section (F): A control section in which acceleration occurs approximately at the start position of the area I (A1). Section (G): A control section in which the speed is decelerated at a fifth gradient within the region I (A1) or to a predetermined set value of the torch target position. Section (H): A control section in which the rotational speed is decelerated at a sixth gradient toward the approximate end position of the region I (A1) or to a predetermined set value of the torch target position. Control (Δ): In the region III (A3), at least one of the following sections (I) to (J) is controlled: Section (I): A control section in which the torch is accelerated at a seventh gradient approximately at the start position of the region III (A3) or to a preset value of the torch target position. Section (J): A control section in which, within the region III (A3), the torch accelerates toward the approximate end position of the region III (A3) at an eighth gradient or to a preset value of the torch target position.

[0120]

[11] A welding control device that installs a guide rail for a workpiece having a corner and controls a welding robot that moves on the guide rail to arc-weld the workpiece, a welding condition setting unit that sets welding conditions at a predetermined torch target position, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A welding control device characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near position WCs1 and near position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each torch target position.

[0121]

[12] A welding system having a guide rail installed for a workpiece having a corner, a welding robot that moves on the guide rail and arc-welds 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A welding system characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near position WCs1 and near position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each torch target position.

[0122]

[13] A control program for a welding robot used in a welding control device that installs a guide rail for a workpiece having a corner 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The control program is configured to cause the welding control device to: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs1 between the boundary position (welding start side) and the approximate center position, Position WCe1 between the approximate center position and the boundary position (welding end side), These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, A control program for a welding robot, characterized in that the movement speed of the welding robot is sharply accelerated or decelerated at least near the position WCs1 and the position WCe1 on the curved surface portion of the workpiece based on the movement speed of the welding robot set for each of the torch target positions. [Explanation of symbols]

[0123] 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 130 Torch connection part 132, 134 Torch clamp 140 parts 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 Power Cable 420 Conduit Tube 430 Power Cable 500 Shielding gas supply source 510 Gas Tube 600 control device 601 Data storage unit 602 Calculation Unit 602a Bevel 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 Unit 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 installed for a workpiece having a corner, a welding robot that moves on the guide rail and arc-welds 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, 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 step of setting a control condition for each of the regions determined in the region determining step, In the step of setting the control condition, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the step of determining the torch target position, the torch target position is determined on the curved surface portion of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs between the boundary position (welding start side) and the approximate center position １ , Position WCe between the approximate center position and the boundary position (welding end side) １ , These three points are set out below. In the step of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, On the curved surface portion of the workpiece, at least the position WCs is determined based on the moving speed of the welding robot set for each of the torch target positions. １ Neighborhood and position WCe １ A method for controlling a welding robot, characterized in that the moving speed of the welding robot is abruptly accelerated or decelerated in the vicinity of the welding robot.

2. In the curved surface portion of the workpiece, The boundary position (start side) and the position WCs １ The interval is interval a, Said position WCs １ The section of the position Cw is section b, The position Cw and the position WCe １ The interval is interval c, The position WCe １ and the section at the boundary position (end side) is section d, In this case, A change in the moving speed of the welding robot during the section a and the section c is controlled to at least one of a constant speed, acceleration, and deceleration; The change in the moving speed of the welding robot during the section b and the section d is as follows: Location WCs １ Or position WCe １ and the moving speed of the welding robot is suddenly accelerated or decelerated.

2. The control method according to claim 1, wherein the control is performed at least one of a constant speed, acceleration, and deceleration.

3. In the region determining step, the region to be determined is at least, Region I (A1): A region where either the guide rail or the workpiece has a curved surface on the welding start position side. Area II (A2): Area where both the guide rail and the workpiece are curved surfaces Region III (A3): Region where either the guide rail or the workpiece has a curved surface on the welding end position side. Area IV (A4): Area where both the guide rail and the workpiece are linear The control method according to claim 2, wherein:

4. In the step of setting the control conditions, the control conditions include a torch angle correction amount, 3. The control method according to claim 2, wherein the control condition calculation unit calculates a torch angle correction amount based on a calculation formula for each of the regions.

5. When the guide rail is a curved surface portion in the region I (A1) and the region III (A3), in the step of setting the control condition, In the section a, deceleration is performed using one type of gradient or a combination of two or more types of gradients, In the section b, after a steep deceleration, Deceleration at one slope or a combination of two or more slopes, or a constant speed, The section c is Acceleration with one or more gradients, or a constant speed, In the section d, after a steep acceleration, acceleration with one kind of gradient or a combination of two or more kinds of gradients is performed. The control method according to claim 3, wherein a moving speed of the welding robot is set.

6. In the step of setting the control conditions, the control conditions include a torch angle correction amount, Based on the torch angle correction amount calculated and set by the control condition calculation unit, Control of tilting the torch angle in the welding forward direction from approximately the start position of region I (A1) to approximately the end position of region I (A1); Controlling the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region II (A2) to approximately the center position of region II (A2); Controlling the torch angle in the welding retreat direction from approximately the center position of the region II (A2) to approximately the end position of the region II (A2); Controlling the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region III (A3) to approximately the end position of region III (A3); 6. The control method according to claim 5, wherein the control conditions are set so as to perform the following.

7. When the workpiece has a curved surface in the region I (A1) and the region III (A3), in the step of setting the control conditions, In the section a, acceleration is performed with one type of gradient or a combination of two or more types of gradients, In the section b, after a steep acceleration, one of acceleration with one gradient or a combination of two or more gradients, and a constant speed is performed, In the section c, either one of deceleration with one gradient or a combination of two or more gradients, or a constant speed is performed, In the section d, after a steep deceleration, deceleration is performed with one kind of gradient or a combination of two or more kinds of gradients. The control method according to claim 3, wherein a moving speed of the welding robot is set.

8. In the step of setting the control conditions, the control conditions include a torch angle correction amount, Based on the torch angle correction amount calculated and set by the control condition calculation unit, Control of tilting the torch angle in the welding retreat direction from approximately the start position of area I (A1) to approximately the end position of area I (A1); Controlling the torch angle in the welding forward direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region II (A2) to approximately the center position of region II (A2); Controlling the torch angle in the welding forward direction from approximately the center position of the region II (A2) to approximately the end position of the region II (A2); Controlling the torch angle in the welding retreat direction so that the torch angle correction amount approaches 0 or near 0 from approximately the start position of region III (A3) to approximately the end position of region III (A3); 6. The control method according to claim 5, wherein the control conditions are set so as to perform the following.

9. 4. The control method according to claim 3, wherein the following controls (α) to (β) are performed based on the moving speed of the welding robot calculated and set by the control condition calculation unit: Control (α): In the region I (A1), 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 (A1). Section (B): A control section in which acceleration is performed at a first gradient within the region I (A1) or to a preset value of the torch target position. Section (C): A control section in which the torch is accelerated at a second gradient toward the approximate end position of the region I (A1) or to a preset value of the torch target position. Control (β): In the region III (A3), at least one of the following sections (D) to (E) is controlled: Section (D): A control section in which the rotational speed is decelerated at a third gradient approximately at the start position of the region III (A3) or to a preset value of the torch target position. Section (E): A control section in which, within the region III (A3), the rotational speed is decelerated at a fourth gradient toward the approximate end position of the region III (A3) or to a preset value of the torch target position.

10. 4. The control method according to claim 3, wherein the following controls (γ) to (Δ) are performed based on the moving speed of the welding robot calculated and set by the control condition calculation unit: Control (γ): In the region I (A1), at least one of the following sections (F) to (H) is controlled. Section (F): A control section in which acceleration occurs approximately at the start position of the region I (A1). Section (G): A control section in which the torch speed is decelerated at a fifth gradient within the region I (A1) or to a preset value of the torch target position. Section (H): A control section in which the speed is decelerated at a sixth gradient toward the approximate end position of the region I (A1) or to a preset value of the torch target position. Control (Δ): In the region III (A3), at least one of the following sections (I) to (J) is controlled: Section (I): A control section in which acceleration is performed at a seventh gradient approximately at the start position of the region III (A3) or to a preset value of the torch target position. Section (J): A control section in which, within the region III (A3), the torch accelerates toward the approximate end position of the region III (A3) at an eighth gradient or to a predetermined set value of the torch target position.

11. A welding control device that installs a guide rail for a workpiece having a corner and controls a welding robot that moves on the guide rail and arc-welds the workpiece, a welding condition setting unit that sets welding conditions at a predetermined torch target position, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs between the boundary position (welding start side) and the approximate center position １ , Position WCe between the approximate center position and the boundary position (welding end side) １ , These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, On the curved surface portion of the workpiece, at least the position WCs is determined based on the moving speed of the welding robot set for each of the torch target positions. １ Neighborhood and position WCe １ A welding control device characterized in that the movement speed of the welding robot is abruptly accelerated or decelerated in the vicinity of the welding robot.

12. A welding system including: a guide rail provided 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The welding control device includes: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs between the boundary position (welding start side) and the approximate center position １ , Position WCe between the approximate center position and the boundary position (welding end side) １ , These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, On the curved surface portion of the workpiece, at least the position WCs is determined based on the moving speed of the welding robot set for each of the torch target positions. １ Neighborhood and position WCe １ A welding system characterized in that the movement speed of the welding robot rapidly accelerates or decelerates in the vicinity.

13. A control program for a welding robot, which is used in a welding control device that sets a guide rail for a workpiece having a corner 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, and a control condition calculation unit that calculates control conditions for controlling the welding conditions to be the conditions set by the welding condition setting unit, The control program is configured to cause the welding control device to: a function of determining the torch target position based on at least guide rail information and workpiece information; a region determination function for determining a region based on the torch target position; a function of setting control conditions for each area determined by the area determination function, In the function of setting the control conditions, setting the control conditions by at least one of calculating the control conditions in the control condition calculation unit and determining the control conditions based on a predetermined database; In the function of determining the torch target position, the torch target position is determined on the curved surface of the workpiece, A boundary position between a curved surface portion and a straight portion of the workpiece; In addition to the boundary position, at least A position Cw that is approximately the center position of the curved surface portion, Position WCs between the boundary position (welding start side) and the approximate center position １ , Position WCe between the approximate center position and the boundary position (welding end side) １ , These three points are set out below. In the function of setting the control conditions, the control conditions include a condition for a moving speed of the welding robot, On the curved surface portion of the workpiece, at least the position WCs is determined based on the moving speed of the welding robot set for each of the torch target positions. １ Neighborhood and position WCe １ A control program for a welding robot, characterized in that the movement speed of the welding robot is abruptly accelerated or decelerated in the vicinity of the welding robot.

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