Control method for portable welding robot, welding control device, portable welding robot, and welding system

Abstract

To provide a portable type welding robot control method that can secure an excellent bead appearance, even if a corner part of a work-piece and a curve part of a guide rail do not exist on a concentric circle and a difference in curvature between the corner part of the work-piece and the curve part of the guide rail is large.SOLUTION: A portable type welding system comprises a portable type welding robot 100 that installs a guide rail on a work-piece Wo having a corner part and moves on the guide rail to arc-weld the work-piece Wo, and a welding control device 600 that controls the portable type welding robot 100. The portable type welding robot 100 comprises a welding torch 200 and a movable part that moves the welding torch 200 in a welding line direction. A portable type welding robot control method comprises: a step in which a torch position determining part 605 determines a torch position on the work-piece Wo; a step in which a torch angle calculating part 606 calculates a torch angle at the torch position; and a step in which the movable part controls the torch angle on the basis of the calculated torch angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Traditionally, in the manufacturing of welded structures such as shipbuilding, steel frames, and bridges, welding work within factories has become increasingly automated, with large multi-axis welding robots being widely used. Meanwhile, even in on-site welding work where large multi-axis welding robots cannot be applied, automation is progressing from manual welding methods such as semi-automatic welding to welding methods using lightweight, compact, portable welding robots that can be carried by a single worker. The application of such portable welding robots can improve welding efficiency in welding sites where welding has previously been carried out manually.

[0003] One example of a technology applying this portable welding robot is Patent Document 1. In Patent Document 1, a guide rail using a corner unit having a straight section and a curved section is attached to the outer circumference of a polygonal rectangular steel pipe to be welded, which is used at construction sites. The welding robot is then slidably mounted on the guide rail. The control unit of the control device controls the movement speed of the welding robot so that the length of the welded portion per unit time (hereinafter also called "bead length") by the welding robot remains constant when the position of the center of curvature of the welded portion to be welded by the welding robot differs from the position of the center of curvature of the position where the welding robot is located on the corner unit when welding the welded portion. This allows for efficient welding of rectangular steel pipes of various shapes. The bead length per unit time by the welding robot is also called the "welding speed". [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-58078 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As described above, Patent Document 1 controls the movement speed of the welding robot (hereinafter also referred to as "robot speed") and changes the welding speed to match the amount of welded material, even when the corner of the workpiece and the curved part of the guide rail (hereinafter also referred to as "rail") are not concentric, thereby enabling efficient welding. However, the technology in Patent Document 1 only considers the control of the robot speed and does not consider the effect of the torch angle, which becomes a problem when the corner of the workpiece and the curved part of the rail are not concentric. In other words, the following issues occur. (1) When the robot is on the curved section of the rail and the torch tip is on the parallel section of the workpiece, the torch angle on the parallel section of the workpiece is either an advancing angle or a receding angle. (2) When the robot is on a curved section of the rail and the tip of the torch is on a corner of the workpiece, the torch angle at the corner of the workpiece is either an advancing angle or a receding angle.

[0006] Furthermore, if the above torch angle becomes an advance angle or a receding angle, the following problems may occur, for example: (In the case of an advance angle) This can easily lead to spatter generation at the front, resulting in poor welding performance. (In the case of a receding angle) This pushes up the molten pool at the rear, resulting in the formation of convex beads near the boundary between corners and straight sections on the workpiece, causing defects in the bead's appearance. Furthermore, as the curvature of the workpiece corners decreases and the difference in curvature between the workpiece and the rail widens, the amount of change in the torch angle increases, and the appearance of the bead at the boundary between the straight section and the corner section deteriorates even further.

[0007] Here, as an example of workpieces with different radii of curvature, we can cite roll-formed polygonal rectangular steel pipes for building structures (BCP) and roll-formed polygonal rectangular steel pipes for building structures (BCR). Generally, the radius of curvature of BCP is calculated as 3.5t relative to the plate thickness t, but the radius of curvature of BCR is 2.5t. In other words, for BCP and BCR with the same plate thickness, if the radius of curvature of the rail is kept constant, the difference between the radius of curvature of the workpiece and the rail is larger for BCR. Therefore, BCR has the characteristic of having a larger change in the torch angle in the curved section of the rail relative to the workpiece, and is more prone to defects in the bead appearance at the boundary between the straight section and the corner section.

[0008] The present invention has been made in view of the aforementioned problems, and its objective is to provide a control method for a portable welding robot, a welding control device, a portable welding robot, and a welding system that can ensure a good bead appearance even when the corners of the workpiece and the curved parts of the rail are not concentric and the difference in curvature between the corners of the workpiece and the curved parts of the rail is large. [Means for solving the problem]

[0009] Therefore, the above objective of the present invention is achieved by the configuration of (A) below relating to a control method for a portable welding robot.

[0010] (A) A method for controlling a portable welding robot using a welding system comprising: a portable welding robot that moves along a guide rail to arc-weld a workpiece having corners, and a welding control device that controls the portable welding robot, The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device includes a torch position determination unit that determines the torch position on the workpiece, and a torch angle calculation unit that calculates the torch angle at the torch position. The steps include determining the torch position on the workpiece using the torch position determination unit, The steps include: calculating the torch angle at the torch position using the torch angle calculation unit; A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following:

[0011] Furthermore, the above objective of the present invention is achieved by the configuration of the welding control device described in (B) below.

[0012] (B) A welding control device for controlling a portable welding robot that installs a guide rail on a workpiece having corners and moves along the guide rail to arc weld the workpiece, The system includes a torch position determination unit that determines the torch position on the workpiece, and a torch angle calculation unit that calculates the torch angle at the torch position. The torch position determination unit determines the torch position on the workpiece, The torch angle calculation unit calculates the torch angle at the torch position, A welding control device characterized by controlling the torch angle based on the calculated torch angle.

[0013] Furthermore, the above objective of the present invention is achieved by the configuration of the portable welding robot described in (C) below.

[0014] (C) A portable welding robot controlled by the welding control device described above, wherein a guide rail is installed for a workpiece having a corner, and the robot moves along the guide rail to arc weld the workpiece, The welding torch and a movable part that moves the welding torch in the direction of the welding line are provided. A portable welding robot characterized in that the movable part controls the torch angle based on the torch angle calculated by the torch angle calculation unit.

[0015] Furthermore, the above objective of the present invention is achieved by the following configuration (D) relating to the welding system.

[0016] (D) A welding system comprising: a portable welding robot that moves along a guide rail to arc-weld a workpiece having a corner, and a welding control device that controls the portable welding robot, The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device includes a torch position determination unit that determines the torch position on the workpiece, and a torch angle calculation unit that calculates the torch angle at the torch position. The torch position determination unit determines the torch position on the workpiece, The torch angle calculation unit calculates the torch angle at the torch position, A welding system characterized by controlling the torch angle by the movable part based on the calculated torch angle.

[0017] Furthermore, the above objective of the present invention is achieved by the configuration of (E) below relating to a control method for a portable welding robot.

[0018] (E) A method for controlling a portable welding robot using a welding system comprising: a portable welding robot that moves along a guide rail to arc weld a polygonal rectangular steel pipe, and a welding control device that controls the portable welding robot, the system comprising: The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device includes a torch position determination unit that determines the torch position on the polygonal rectangular steel pipe, and a torch angle calculation unit that calculates the torch angle at the torch position. The steps include determining the torch position on the polygonal rectangular steel pipe using the torch position determination unit, The steps include: calculating the torch angle at the torch position using the torch angle calculation unit; A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following: [Effects of the Invention]

[0019] According to the control method for the portable welding robot of the present invention, even when the corner of the workpiece and the curved part of the guide rail are not concentric and the difference in curvature between the corner of the workpiece and the curved part of the guide rail is large, the torch angle can be controlled according to the torch position information on the workpiece to improve the appearance of the weld bead at the corners on the workpiece and at the boundary between the corners and straight parts. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram of one embodiment of the welding system according to the present invention. [Figure 2] Figure 2 is a schematic side view of the portable welding robot shown in Figure 1. [Figure 3] Figure 3 is a perspective view of the portable welding robot shown in Figure 2. [Figure 4] Figure 4 is a perspective view of the welding robot shown in Figure 3 when it is attached to a polygonal rectangular steel pipe. [Figure 5] Figure 5 is a diagram illustrating the positional relationship between the guide rail and the region of the 1 / 4 corner of the polygonal rectangular steel pipe when viewed from directly above as shown in Figure 4. [Figure 6] Figure 6 is a diagram of Figure 5. [Figure 7] Figure 7 is a graph showing the relationship between the angle θ of the straight line connecting the center of curvature of the guide rail and the portable welding robot on the guide rail, and the torch angle correction amount θT. [Figure 8] Figure 8 is a graph showing the relationship between the travel distance D of a portable welding robot and the torch angle correction amount θT. [Modes for carrying out the invention]

[0021] A welding system according to one embodiment of the present invention will be described below with reference to the drawings. Note that this embodiment is an example using a portable welding robot, and the welding system of the present invention is not limited to the configuration of this embodiment.

[0022] <Configuration of the welding system> Figure 1 is a schematic diagram showing the configuration of the welding system according to this embodiment. As shown in Figure 1, the welding system 50 includes a portable welding robot 100, a feed device 300, a welding power supply 400, a shielding gas supply source 500, and a control device 600.

[0023] [Control device] The control device 600 is connected to the portable welding robot 100 by a robot control cable 620 and to the welding power supply 400 by a power supply control cable 630.

[0024] The control device 600 has previously set up work information, guide rail information, and work W o The system also has a data holding unit 601 that holds teaching data that defines the position information of the guide rail 120, the operation pattern of the portable welding robot 100, the welding start position, the welding end position, welding conditions, weaving operation, etc. Based on this teaching data, it sends commands to the portable welding robot 100 and the welding power supply 400 to control the operation of the portable welding robot 100 and the welding conditions.

[0025] Furthermore, the control device 600 includes a groove shape calculation unit 602 that calculates groove shape information from detection data obtained by sensing such as touch sensing and visual sensors, and a welding condition calculation unit 603 that corrects the welding conditions of the teaching data based on the groove shape information to acquire welding conditions. In addition, the portable welding robot 100 includes a speed control unit 604 that controls a drive unit (not shown) for driving in the X, Y, and Z directions, which will be described later, a torch position determination unit 605 that determines the torch position, and a torch angle calculation unit 606 that controls the torch angle drive unit (movable arm unit 116) in the portable welding robot 100.The control unit 610 is configured to include the groove shape calculation unit 602, the welding condition calculation unit 603, the speed control unit 604, the torch position determination unit 605, and the torch angle calculation unit 606.Note that the torch position determination unit 605 and the torch angle calculation unit 606 can also be configured as a single unit.

[0026] Furthermore, the control device 600 is formed by integrating a controller for teaching and a controller with other control functions. However, the control device 600 is not limited to this configuration, and may be divided into multiple units depending on their roles, such as separating the controller for teaching and the controller with other control functions into two units. Also, the control device 600 may be included within the portable welding robot 100, or, as shown in Figure 1, the control device 600 may be provided independently of the portable welding robot 100. In other words, the welding system having the portable welding robot 100 and the control device 600 described in this embodiment includes both cases in which the control device 600 is included within the portable welding robot 100 and cases in which it is provided independently of the portable welding robot 100. In addition, in this embodiment, signals are sent using the robot control cable 620 and the power control cable 630, but this is not limited to this, and signals may be transmitted wirelessly. From the viewpoint of usability in the welding site, it is preferable to separate the controller into two units: one for teaching and one with other control functions.

[0027] [Welding power supply] The welding power supply 400, in accordance with commands from the control device 600, supplies a consumable electrode (hereinafter also referred to as "welding wire") 211 and a workpiece W o By supplying power to the welding wire 211 and the workpiece W o An arc is generated between the two. Power from the welding power source 400 is sent to the feeder 300 via the power cable 410, and from the feeder 300 to the welding torch 200 via the conduit tube 420. Then, as shown in Figure 2, it is supplied to the welding wire 211 via the contact tip at the tip of the welding torch 200. The current during welding can be either DC or AC, and its waveform is not particularly specified. Therefore, the current may be a pulse such as a square wave or a triangular wave.

[0028] Furthermore, the welding power supply 400 is connected, for example, with power cable 410 as the positive (+) electrode connected to the welding torch 200 side, and power cable 430 as the negative (-) electrode connected to the workpiece W o It is connected to the workpiece W. Note that this is when welding with reverse polarity; when welding with positive polarity, the positive (+) power cable is connected to the workpiece W. o It should be connected to the side and then connected to the welding torch 200 side via a negative (-) power cable.

[0029] [Shielding gas supply source] The shielding gas supply source 500 consists of a container filled with shielding gas and ancillary components such as a valve. From the shielding gas supply source 500, the shielding gas is sent to the supply device 300 via the gas tube 510. The shielding gas sent to the supply device 300 is sent to the welding torch 200 via the conduit tube 420. The shielding gas sent to the welding torch 200 flows inside the welding torch 200, is guided by the nozzle 210, and is ejected from the tip side of the welding torch 200. As the shielding gas used in this embodiment, for example, argon (Ar), carbon dioxide (CO2), or a mixture of these gases can be used.

[0030] [Feeding device] The feeding device 300 feeds the welding wire 211 and sends it to the welding torch 200. The welding wire 211 sent by the feeding device 300 is not particularly limited and is used with the workpiece W o The type of welding wire is selected based on its properties and welding configuration, and for example, solid wire or flux-cored wire (hereinafter also referred to as "FCW") may be used. Furthermore, the material of the welding wire 211 is not limited; for example, mild steel, stainless steel, aluminum, or titanium may be used. In addition, the wire diameter of the welding wire 211 is not particularly limited, but in this embodiment, the preferred wire diameter is 1.6 mm at the upper limit and 0.9 mm at the lower limit.

[0031] In this embodiment, the conduit tube 420 has a conductive path formed on the outer sheath side of the tube for functioning as a power cable, and a protective tube for protecting the welding wire 211 is arranged inside the tube, and a flow path for shielding gas is formed. However, the conduit tube 420 is not limited to this, and for example, a bundle of power supply cables and shielding gas supply hoses can be used with a protective tube for supplying the welding wire 211 to the welding torch 200 at its center. Alternatively, for example, the tube for supplying the welding wire 211 and shielding gas and the power cable can be installed separately.

[0032] [Portable welding robot] As shown in Figures 2 and 3, the portable welding robot 100 comprises a guide rail 120, a robot body 110 mounted on the guide rail 120 and moving along the guide rail 120, and a torch connection part 130 mounted on the robot body 110. The robot body 110 mainly consists of a housing part 112 mounted on the guide rail 120, a fixed arm part 114 attached to the housing part 112, and a movable arm part 116 attached to the fixed arm part 114 in a manner that allows it to rotate in the direction of arrow R1.

[0033] The torch connection part 130 is attached to the movable arm part 116 via a crank 170 which is a movable part that moves the welding torch 200 in the welding line direction, that is, the X direction. The torch connection part 130 includes a torch clamp 132 and a torch clamp 134 that fix the welding torch 200. Further, on the housing part 112, on the side opposite to the side where the welding torch 200 is mounted, a cable clamp 150 that supports a conduit tube 420 connecting the feeding device 300 and the welding torch 200 is provided.

[0034] Also, in the present embodiment, a voltage is applied between the work W o and the welding wire 211, and the voltage drop phenomenon that occurs when the welding wire 211 contacts the work W o is utilized to sense the surface of the groove 10 on the work W o and the like, and a touch sensor is used as a detection means. The detection means is not limited to the touch sensor of the present embodiment, and an image sensor, that is, visual sensing or laser sensor, that is, laser sensing, etc., or a combination of these detection means may be used, but it is preferable to use the touch sensor of the present embodiment for the simplicity of the device configuration.

[0035] The housing part 112 of the robot body 110 includes a robot drive part (not shown) that drives in the direction perpendicular to the paper surface, that is, the X direction in which the robot body 110 moves along the guide rail 120, as shown by the arrow X in FIG. 2. Further, the housing part 112 is also drivable in the Z direction that moves in the depth direction of the groove 10 perpendicular to the X direction. Also, the fixed arm part 114 is drivable in the Y direction which is the width direction of the groove 10 perpendicular to the X direction with respect to the housing part 112 via the slide support part 113.

[0036] Furthermore, the torch connection part 130 to which the welding torch 200 is attached can be driven to swing back and forth in the X direction, that is, in the welding line direction, by the rotation of the crank 170 as shown by the arrow R2 in FIG. 3. Also, the movable arm part 116 is rotatably attached to the fixed arm part 114 as shown by the arrow R1, and can be adjusted and fixed at an optimal angle.

[0037] As described above, the robot body 110 can drive its tip, the welding torch 200, with three degrees of freedom. However, the robot body 110 is not limited to this, and may be driven with any number of degrees of freedom depending on the application.

[0038] As configured above, the tip of the welding torch 200 attached to the torch connection part 130 can be directed in any direction. Furthermore, the robot body 110 can be driven along the guide rail 120 in the X direction in Figure 2. Weaving welding can be performed by moving the welding torch 200 back and forth in the Y direction while the robot body 110 moves in the X direction. In addition, the welding torch 200 can be tilted according to the construction conditions, such as by setting an advance angle or a retraction angle, by driving the crank 170. Furthermore, by tilting the welding torch 200 in the X direction by driving the crank 170, the workpiece W such as a polygonal rectangular steel pipe described later can be welded. o This allows for correction of changes in the torch angle, i.e., the forward or backward angle, that occur when the curvature of the corner WC and the curved section 122 of the guide rail 120 are different.

[0039] Below the guide rail 120, a mounting member 140, such as a magnet, is provided, and the guide rail 120 is attached to the workpiece W by the mounting member 140. o It is designed to be easily attached to and detached from the workpiece W. o When setting up, the operator grasps the handles 160 on both sides of the portable welding robot 100, thereby moving the portable welding robot 100 to the workpiece W o It can be easily set on top.

[0040] <Method for controlling the torch angle> Next, a specific example of how torch angle control is performed when welding polygonal rectangular steel pipes using a portable welding robot that travels on a guide rail will be described. Figure 4 is a perspective view of the portable welding robot 100 shown in Figure 3 when it is attached to a polygonal rectangular steel pipe. As shown in Figure 4, the guide rail 120 is located on the workpiece W o The guide rail is attached to the outer surface of the polygonal rectangular steel pipe along the circumferential direction. In this case, the guide rail 120 is provided around the outer surface of the steel pipe via a mounting member 140 and has a shape having a straight section 121 and a curved section 122. The portable welding robot 100 is mounted on the guide rail 120 with the welding torch 200 facing downwards. Furthermore, Figure 5 shows the polygonal rectangular steel pipe W as seen from directly above in Figure 4. o This diagram illustrates the positional relationship between the guide rail 120 and the area of ​​the quarter corner.

[0041] The guide rail 120 shown in Figures 4 and 5 has a straight section 121, a curved section 122, and a boundary point 128 where the guide route changes between the straight section 121 and the curved section 122. Also, the polygonal rectangular steel pipe W o In this configuration, there is a straight section WL, a corner (curved section) WC, and a boundary point WB between the straight section WL and the corner WC.

[0042] In this specific example, the radius of curvature RA of the curved section 122 in the guide rail 120 is the polygonal rectangular steel pipe W o The radius of curvature of the corner WC is greater than RB, and the polygonal square steel pipe W o The corner WC and the curved section 122 of the guide rail 120 are not concentric. Furthermore, the radius of curvature RA of the curved section 122 in the guide rail 120 and the polygonal rectangular steel pipe W o In this example, the radius of curvature RB of the corner WC differs between the outer and inner circumferences, but as long as the total amount of welded material is the same, the average value of the outer and inner circumferences is used.

[0043] As shown in Figure 5, the radius of curvature RA of the curved section 122 in the guide rail 120 is equal to the center of curvature O of the curved section 122. Aand the rail center R of guide rail 120 c The distance to the polygonal rectangular steel pipe W o The radius of curvature RB of the corner WC is the center of curvature O of the corner WC. B and polygonal rectangular steel pipe W o Plate thickness center W c This represents the distance to [the specified location].

[0044] The radius of curvature RA of the curved section 122 of the guide rail 120, and the polygonal rectangular steel pipe W o The radii of curvature RB of the corners WC are different (in this specific example, RA > RB), and they are not on concentric circles, resulting in a polygonal rectangular steel pipe W o The welding area is such that the portable welding robot 100 is on the straight section 121 of the guide rail 120, and the welding torch 200 is on a polygonal rectangular steel pipe W o The first region I is located in the straight section WL, and the portable welding robot 100 is located in the curved section 122 of the guide rail 120, and the welding torch 200 is located in the polygonal rectangular steel pipe W. o The second region II is located in the straight section WL, and the portable welding robot 100 is located in the curved section 122 of the guide rail 120, and the welding torch 200 is located in the polygonal rectangular steel pipe W o It can be divided into three parts: the third area III located in the corner WC.

[0045] The portable welding robot 100 travels along the guide rail 120 while welding polygonal rectangular steel pipes W based on the operation signals of the control device 600. o The guide rail 120 has a straight section 121, a curved section 122, and a boundary point 128, but in order to maintain a substantially constant welding quality over the entire length of the weld, it is preferable that the torch angle of the welding torch 200 is substantially constant regardless of the position of the portable welding robot 100 on the guide rail 120. Any position on the guide rail 120 includes, for example, the straight section 121, the curved section 122, and the boundary point 128, and the torch angle in the first region I is the polygonal rectangular steel pipe W o It is perpendicular to the, but in the second region II and the third region III, the welding torch 200 is perpendicular to the polygonal square steel pipe W oThere are cases where it is not perpendicular to it. The torch angle is the polygonal rectangular steel pipe W in the first region I. o It is preferable to control the torch angle to be approximately constant, using the torch angle in the straight section WL as a reference.

[0046] Here, "approximately constant torch angle" means that the angle is within a practically controllable range and allows for an angle error that does not significantly affect the welding quality. Specifically, in this embodiment, the angle error is preferably within ±10°, more preferably within ±5°, and most preferably substantially 0°.

[0047] Specifically, in Figure 5, the polygonal rectangular steel pipe W o If, for example, the welding torch 200 is perpendicular to the straight section WL of the guide rail 120, i.e., the torch angle is 0°, and the portable welding robot 100 moves counterclockwise from the lower right to the upper part of the diagram along the straight section 121 of the guide rail 120, then the portable welding robot 100 will move the welding torch 200 along the polygonal rectangular steel pipe W o Before reaching the corner WC, it reaches the curved section 122 on the guide rail 120 and exits the first region I.

[0048] In other words, the welding torch 200 of the portable welding robot 100 is used to weld a polygonal rectangular steel pipe W o Even though the robot body 110 is positioned on the straight section WL, when the robot body 110 enters the second region II located on the curved section 122 of the guide rail 120, the welding torch 200 tilts, and the torch angle changes as it becomes either a greater forward or greater backward angle. Since this change in torch angle may affect the welding quality, it is necessary to control the torch angle to be approximately constant.

[0049] Therefore, the torch position determination unit 605 of the control device 600 determines the torch position based on the torch position information (torch position determination step), and the guide rail 120 and polygonal rectangular steel pipe W that have been input to the control device 600 in advance are determined. o Based on information such as size and shape, the torch angle correction amount θ is calculated based on the amount of deviation in the torch angle. TThe torch angle is calculated (torch angle calculation step). The calculated deviation in the torch angle is then input to the control device 600 as a correction value for the torch angle, and the crank 170, which is a movable part, rotates as shown by arrow R2 in Figure 3 to correct the deviation in the torch angle (torch angle control step).

[0050] Furthermore, the acquisition of position information input to the torch position determination unit 605 for torch position determination is performed using a sensing function such as a laser sensor on the polygonal rectangular steel pipe W o The control device 600 is made to recognize the size of the rail, and the rail size can be manually input to the control device 600, or the teaching point positions, which are pre-stored in the data holding unit 601, can be acquired as position information.

[0051] Polygonal rectangular steel pipe W at the work site o The actual relative position of the guide rail 120 is that of the polygonal rectangular steel pipe W o And the manufacturing tolerance of the guide rail 120, and the polygonal rectangular steel pipe W o Misalignment may occur due to mounting errors of the guide rail 120 relative to the workpiece W. Therefore, it is preferable for the torch position determination unit 605 to take this misalignment into account when making a determination. o Furthermore, when acquiring positional information of the guide rail 120 using a sensing function, it is preferable because the influence of misalignment is eliminated. The sensing function is not particularly limited, but it is preferable to determine the torch position using at least one sensing method from touch sensing, laser sensing, and visual sensing, or by combining these sensing methods.

[0052] The torch angle calculation unit 606 calculates the workpiece information, guide rail information, and workpiece W o The torch angle is calculated based on the position information of the guide rail 120. This information may be obtained through sensing or other means, or it may be numerical data of each piece of information that is stored in the data holding unit 601 beforehand.

[0053] <Method for calculating torch angle> Next, the method for calculating the torch angle will be explained in detail with reference to Figures 5 to 8.

[0054] Here, as the guide rail 120, for example, a guide rail 120 with RA=261mm is used, and polygonal rectangular steel pipe W o This section describes an example of using BCR polygonal rectangular steel pipes. o There are BCR and BCP, but both are polygonal rectangular steel pipes W o However, the radius of curvature relative to the plate thickness is determined by the standard.

[0055] Figure 6 shows the guide rail 120 (rail) and the polygonal rectangular steel pipe W. o This diagram shows the area of ​​the 1 / 4 corner of the (column), with each line representing the center line R of the guide rail 120. c , and polygonal rectangular steel pipe W o Centerline W c This shows that, as shown in Figure 6, the center of curvature of the quadrant of the guide rail 120 is O A , radius of curvature RA, polygonal square steel pipe W o The center of curvature of the quadrant at the corner is O B Let RB be the radius of curvature, and O be the center of curvature. B Let d1 be the x-coordinate and O be the center of curvature. B Let the Y coordinate of be d2. Also, assume that the portable welding robot 100 is located at point A on the guide rail 120, and the center of curvature O A And let θ be the angle between the line segment LA connecting point A and the X-axis, and let O be the center of curvature. B The angle between the line segment LB connecting point A and the X-axis is denoted by θ1. Note that the straight section 121 of the guide rail 120 and the polygonal rectangular steel pipe W o The straight section WL is a parallel straight section as shown in Figure 5. The second and fourth quadrants, which are not shown in Figure 6, are outside the scope of this explanation because the torch angle remains constant at 0°.

[0056] Assuming that the portable welding robot 100 moves counterclockwise from point A0 on the X-axis, which corresponds to boundary point 128 in Figure 5, the line segment LA is the polygonal rectangular steel pipe W. oIn the section up to the boundary point B0 between the straight section WL and the corner section WC, i.e., in the second region II, the torch angle correction amount θ is calculated based on alternate interior angles. T =θ, and in the third region III, where line segment LA is between point B0 and point B1, the torch angle correction amount θ T It is expressed as =θ-θ1, and the torch angle correction amount θ in the second region II is the amount of time from when the line segment LA passes through the boundary point B1 between the corner WC and the straight section WL until it coincides with the Y axis. T It can be expressed as =90°-θ

[0057] Torch angle correction amount θ in the second region II T Since the angle between line segment LA and the X-axis can be easily determined if θ is known, in the following, the torch angle correction amount θ is given in the third region III, where line segment LA is between point B0 and point B1, i.e., 0 ≤ θ1 < 90°. T This will be explained in detail.

[0058] In the third area III, the torch angle correction amount θ T =θ-θ1, therefore tanθ T =tan(θ-θ1)=(tanθ-tanθ1) / (1+tanθ×tanθ1). Therefore, we get equation (1). θ T =tan -1 (tanθ-tanθ1) / (1+tanθ×tanθ1)...(1)

[0059] Here, the XY coordinates of point A are (RAcosθ, RAsinθ), so we get equation (2). tanθ1=(RAsinθ-d2) / (RAcosθ-d1)...(2)

[0060] Substituting equation (2) into equation (1), we get equation (3). θ T =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 0 ≤ θ1 < 90°.

[0061] Here, the radius RA of the guide rail 120 is 261 mm, and the polygonal rectangular steel pipe W o Substituting the radii RB=62.5mm, d1=40mm, and d2=40mm of the corner WC into equation (3), we can calculate the angle θ and the torch angle correction amount θ. T The relationship can be determined as shown in Figure 7.

[0062] Furthermore, the relationship "D = θ (rad) × RA" holds between the angle θ between line segment LA and the X-axis and the distance D traveled from point A0 on the guide rail 120 of the portable welding robot 100. Therefore, the angle θ between line segment LA and the X-axis can be converted to the distance D (mm) traveled from point A0, and the distance D (mm) and the torch angle correction amount θ can be converted. T The relationship is shown in Figure 8.

[0063] Therefore, as shown in Figures 7 and 8, in the range of 0°≦θ<45° and 0mm≦D<205mm, the torch angle correction amount θ T The torch angle is corrected to the forward angle side by a certain amount, and in the range of 45°≦θ<90° and 205mm≦D<410mm, the torch angle correction amount θ T By correcting the torch angle toward the reverse angle by a certain amount, the torch angle is maintained at a constant angle. Note that the positions θ=9°, i.e., D=41mm, and θ=81°, i.e., D=369mm, correspond to the boundary point WB between the straight section WL and the corner section WC shown in Figure 5.

[0064] This will allow you to work with o The corner WC and the curved section 122 of the guide rail 120 are not on the same circle, and the workpiece W o Even when there is a large difference in curvature between the corner WC and the curved section 122 of the guide rail 120, welding can be performed with a substantially constant torch angle around the entire circumference of the weld, ensuring a good bead appearance.

[0065] (Other welding conditions) In order to maintain a substantially constant welding quality throughout the entire length of the weld, it is preferable that other welding conditions, including the torch angle mentioned above, are also substantially constant. Other welding conditions include a portable welding robot 100 for polygonal square steel pipes W o Before welding begins, the welding conditions can also be acquired using the robot body 110, which moves along the guide rail 120. Specifically, the robot body 110 is driven based on the operation signal of the control device 600, the groove shape is automatically sensed by a touch sensor, the groove condition calculation unit 602 calculates groove shape information, and further, the welding condition calculation unit 603 calculates the welding conditions based on the groove shape information and teaching data held by the data holding unit 601. Groove shape information includes, for example, groove shape, plate thickness, and start / end points, while welding conditions include, for example, welding current, arc voltage, tip-to-base metal distance, and welding speed. Alternatively, welding may be performed based on teaching data of welding conditions pre-set for each teaching point position on the guide rail, without performing automatic sensing of the groove shape.

[0066] Furthermore, torch position information can also be obtained from the teaching point positions on the guide rail, which are pre-stored in the data holding unit 601. Examples of torch position information include straight sections, curved sections, boundary points, and torch angles of the guide rail. This information may also be obtained by an image sensor, a laser sensor, or a detection means combining these detection means.

[0067] For example, in order to keep the amount of welded material approximately constant along the entire length of the weld, the robot speed of the portable welding robot 100 calculated by the welding condition calculation unit 603 is controlled so that the robot speed in the curved section 122 of the guide rail 120 is faster than the robot speed in the straight section 121. Basically, the robot speed changes based on the teaching points, and the speed between teaching points should be changed, for example, in a curved, straight, or stepped manner. Specifically, the robot speed of the portable welding robot 100 refers to the travel speed of the portable welding robot 100 in the X direction on the guide rail 120.

[0068] That is, the robot speed V in the curved section 122 of the guide rail 120, which is the second region II and the third region III. o This refers to the radius of curvature RA of the curved section 122 of the guide rail 120 and the polygonal rectangular steel pipe W. o The ratio RA / RB of the radius of curvature RB of the corner WC and the set robot speed V set in the straight section 121. c The product V o =V c It is calculated as ×(RA / RB). The speed control unit 604 controls the robot speed of the portable welding robot 100 based on the robot speed calculated by the welding condition calculation unit 603.

[0069] Furthermore, in the second area II and the third area III, polygonal rectangular steel pipes W o The heat input changes relative to the heat input in the first region I. Therefore, the welding conditions are controlled so that the heat inputs in the second region II and the third region III are within ±20% of the heat input in the first region I. This results in a polygonal rectangular steel pipe W o The heat input in the straight section WL and the corner section WC is controlled to be approximately constant, and approximately constant welding conditions are maintained, so the polygonal square steel pipe W o The joint appearance of the straight section WL and the corner section WC will be the same shape. The welding conditions referred to here include, for example, robot speed, welding current, welding voltage, and overhang length, and one or more of these conditions will be selected.

[0070] Furthermore, the present invention is not limited to the embodiments described above, and can be modified, improved, and so on as appropriate.

[0071] For example, in the above embodiment, sensing was performed using a touch sensor, but sensing may also be performed using other sensors such as laser sensors, vision sensors, or a combination thereof.

[0072] In addition, in the above embodiment, the data used for setting the welding conditions is automatically set by automatic sensing. However, it may be input to the control device 600 in advance by teaching or the like.

[0073] In addition, the polygonal square steel pipe W o and the shape of the guide rail 120 may be converted into the XY coordinate system from CAD data, or may be converted into the XY coordinate system based on sensing. Further, the shape information of the polygonal square steel pipe W o and the guide rail 120 may be input to the data holding unit 601 in advance, and may be converted into the XY coordinate system based on the shape information.

[0074] In addition, in the above embodiment, the radius of curvature RA of the curved portion 122 of the guide rail 120 is described as being larger than the radius of curvature RB of the corner portion WC of the polygonal square steel pipe W o , that is, in the case of RA>RB. However, even when the radius of curvature RA of the curved portion 122 of the guide rail 120 is smaller than the radius of curvature RB of the corner portion WC of the polygonal square steel pipe W o , that is, in the case of RA<RB, the present invention can be similarly applied.

[0075] As described above, the following matters are disclosed in this specification.

[0076] (1) A control method for a portable welding robot using a welding system having a portable welding robot that installs a guide rail for a workpiece having a corner portion and moves on the guide rail to arc-weld the workpiece, and a welding control device that controls the portable welding robot, where the portable welding robot has a welding torch and a movable part that moves the welding torch in the welding line direction, the welding control device has a torch position determination unit that determines the torch position on the workpiece and a torch angle calculation unit that calculates the torch angle at the torch position, a step of determining the torch position on the workpiece by the torch position determination unit, The steps include: calculating the torch angle at the torch position using the torch angle calculation unit; A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following: With this configuration, even when the corners of the workpiece and the curved sections of the guide rail are not concentric, and there is a large difference in curvature between the corners of the workpiece and the curved sections of the guide rail, the torch angle can be controlled to a nearly constant angle to ensure a good bead appearance.

[0077] (2) The control method for a portable welding robot according to (1), characterized in that the torch position determination unit determines the torch position by at least one sensing means among touch sensing, laser sensing, and visual sensing, or determines the torch position by a predetermined teaching point position. With this configuration, the torch position can be automatically determined by the sensing function. Furthermore, the torch position can be determined from teaching data stored in the data storage unit.

[0078] (3) The control method for a portable welding robot according to (1) or (2), characterized in that the torch angle calculation unit calculates the torch angle based on workpiece information, guide rail information, and position information of the workpiece and the guide rail. This configuration allows for the calculation of changes in the torch angle that occur in the curved sections of the guide rail, and by controlling the torch angle, the bead appearance can be improved at the straight sections, corners, and the boundary positions between corners and straight sections on the workpiece.

[0079] (4) The welding control device includes a welding condition calculation unit, A control method for a portable welding robot according to any one of (1) to (3), characterized in that the torch angle is controlled and welding conditions are controlled at the torch position. This configuration allows welding to be performed under optimal welding conditions for each welding location.

[0080] (5) The control method for a portable welding robot according to (4), characterized in that the control of the welding conditions is performed by controlling at least one of the following conditions: welding current, arc voltage, tip-base metal distance, and robot movement speed. With this configuration, the optimal welding conditions can be selected and used for each welding location.

[0081] (6) A control method for a portable welding robot according to any one of (1) to (5), characterized in that the movable part controls the torch angle so that the torch angle in the straight portion and corner portion of the workpiece is substantially constant, with reference to the torch angle in the straight portion of the workpiece. With this configuration, even when the corners of the workpiece and the curved sections of the guide rail are not concentric, and there is a large difference in curvature between the corners of the workpiece and the curved sections of the guide rail, the torch angle can be maintained at a nearly constant level, ensuring a good bead appearance.

[0082] (7) The control method for a portable welding robot according to (3), characterized in that the torch angle calculation unit calculates the torch angle based on the radius of curvature value at the corner of the workpiece and the radius of curvature value at the curved portion of the guide rail at the torch position. This configuration allows for the accurate calculation of the deviation angle of the torch angle at each welding position.

[0083] (8) A control method for a portable welding robot according to (4) or (5), characterized in that the welding conditions are controlled such that the heat input at the corners and the heat input in the boundary region between the straight section and the corners are within ±20% of the heat input at the straight section of the workpiece. With this configuration, even when the corners of the workpiece and the curved sections of the guide rail are not concentric, and there is a large difference in curvature between the corners of the workpiece and the curved sections of the guide rail, a good bead appearance can be ensured by controlling the heat input.

[0084] (9) A welding control device for controlling a portable welding robot that installs a guide rail on a workpiece having corners and moves along the guide rail to arc weld the workpiece, The system includes a torch position determination unit that determines the torch position on the workpiece, and a torch angle calculation unit that calculates the torch angle at the torch position. The torch position determination unit determines the torch position on the workpiece, The torch angle calculation unit calculates the torch angle at the torch position, A welding control device characterized by controlling the torch angle based on the calculated torch angle. With this configuration, even in areas where the corners of the workpiece and the curved sections of the guide rail are not concentric and where there is a large difference in curvature between the corners of the workpiece and the curved sections of the guide rail, the torch angle can be kept approximately constant to ensure a good bead appearance.

[0085] (10) A portable welding robot controlled by the welding control device described in (9), wherein a guide rail is installed for a workpiece having corners, and the robot moves along the guide rail to arc weld the workpiece, The welding torch and a movable part that moves the welding torch in the direction of the welding line are provided. A portable welding robot characterized in that the movable part controls the torch angle based on the torch angle calculated by the torch angle calculation unit. With this configuration, the angular deviation of the torch angle at each welding position can be corrected by the movable part, allowing welding to be performed at a substantially constant torch angle.

[0086] (11) A welding system comprising: a portable welding robot that moves along a guide rail to arc weld a workpiece having corners; and a welding control device that controls the portable welding robot, The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device includes a torch position determination unit that determines the torch position on the workpiece, and a torch angle calculation unit that calculates the torch angle at the torch position. The torch position determination unit determines the torch position on the workpiece, The torch angle calculation unit calculates the torch angle at the torch position, A welding system characterized by controlling the torch angle by the movable part based on the calculated torch angle. With this configuration, the torch angle deviation at each welding position is calculated by the torch angle calculation unit, and the torch angle is controlled by the movable unit to correct the angle deviation, thereby enabling welding at a substantially constant torch angle.

[0087] (12) A method for controlling a portable welding robot using a welding system comprising: a portable welding robot that moves along a guide rail to arc weld a polygonal rectangular steel pipe, and a welding control device that controls the portable welding robot, the system comprising: The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device includes a torch position determination unit that determines the torch position on the polygonal rectangular steel pipe, and a torch angle calculation unit that calculates the torch angle at the torch position. The steps include determining the torch position on the polygonal rectangular steel pipe using the torch position determination unit, The steps include: calculating the torch angle at the torch position using the torch angle calculation unit; A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following: With this configuration, a portable welding robot mounted on a guide rail can weld the entire circumference of the welded section of a polygonal rectangular steel pipe at a substantially constant torch angle, ensuring a good bead appearance. [Explanation of Symbols]

[0088] 50 Welding system 100 Portable welding robot 120 Guide rail 121 Straight section (of guide rail) 122 Curved section (of guide rail) 128 Boundary point (of guide rail) 170 Crank (movable part) 200 Welding torch 300 Feeding device 400 Welding power source 500 Shielding gas supply source 600 Control device (welding control device) 603 Welding condition calculation section 605 Torch position determination section 606 Torch angle calculation section d1 X coordinate of curvature center O B of d2 Y coordinate of curvature center O B of LA Line segment connecting curvature center O A and point A LB Line segment connecting curvature center O B and point A O A Curvature center of the curved section (of guide rail) O B Curvature center of the corner (of workpiece) RA Curvature radius of the curved section of guide rail RB Curvature radius of the corner of workpiece W o Workpiece (polygonal angle steel pipe) WL Straight section (of workpiece) WC Corner (curved section) of workpiece WB Boundary point (of workpiece) I First region II Second region III Third region θ Angle formed by line segment LA and X-axis θ1 Angle formed by line segment LB and X-axis θ T Torch angle correction amount

Claims

1. A method for controlling a portable welding robot using a welding system comprising: a portable welding robot that moves along a guide rail to arc-weld a workpiece having corners; and a welding control device that controls the portable welding robot, the method comprising: The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device is A torch position determination unit for determining the torch position on the workpiece, A torch angle calculation unit that calculates the torch angle at the aforementioned torch position, It has, A step of acquiring positional information of at least the workpiece and the guide rail based on at least one sensing means among touch sensing, laser sensing, and visual sensing, The steps include determining the torch position on the workpiece using the torch position determination unit, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a straight section in a first region, A second region in which one of the positions of the portable welding robot on the guide rail and the position of the welding torch on the workpiece is in a straight section and the other is in a curved section, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a third region located on a curved section, The step of dividing into these areas, The torch angle calculation unit calculates the torch angle at the torch position for each region based on the positional information of at least the workpiece and the guide rail, A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following:

2. The control method for a portable welding robot according to claim 1, characterized in that the torch position determination unit determines the torch position using the sensing means or determines the torch position using a predetermined teaching point position.

3. The control method for a portable welding robot according to claim 1 or 2, characterized in that the torch angle calculation unit calculates the torch angle based on workpiece information and guide rail information.

4. The welding control device includes a welding condition calculation unit that calculates welding conditions other than the torch angle at the torch position, The control method for a portable welding robot according to claim 1, characterized in that the control of the other welding conditions involves controlling at least one of the following conditions: welding current, arc voltage, tip-base metal distance, and robot movement speed.

5. The control method for a portable welding robot according to any one of claims 1 to 4, characterized in that the movable part controls the torch angle so that the torch angle in the straight portion and corner portion of the workpiece is substantially constant, based on the torch angle in the straight portion of the workpiece.

6. The control method for a portable welding robot according to claim 3, characterized in that the torch angle calculation unit calculates the torch angle based on the radius of curvature value at the corner of the workpiece and the radius of curvature value at the curved portion of the guide rail at the torch position.

7. The control method for a portable welding robot according to claim 4, characterized in that the other welding conditions are controlled such that the heat input at the corners and the heat input in the boundary region between the straight section and the corners are within a range of ±20% of the heat input at the straight section of the workpiece.

8. A welding control device for controlling a portable welding robot that installs a guide rail on a workpiece having corners and moves along the guide rail to arc weld the workpiece, The aforementioned portable welding robot is equipped with a welding torch, A torch position determination unit for determining the torch position on the workpiece, A torch angle calculation unit that calculates the torch angle at the aforementioned torch position, It has, Position information of at least the workpiece and the guide rail is acquired based on at least one sensing means among touch sensing, laser sensing, and visual sensing. The torch position determination unit determines the torch position on the workpiece, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a straight section in a first region, A second region in which one of the positions of the portable welding robot on the guide rail and the position of the welding torch on the workpiece is in a straight section and the other is in a curved section, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a third region located on a curved section, Divided into the following areas, The torch angle calculation unit calculates the torch angle at the torch position for each region based on at least the position information of the workpiece and the guide rail, A welding control device characterized by controlling the torch angle based on the calculated torch angle.

9. A portable welding robot controlled by a welding control device according to claim 8, wherein a guide rail is installed on a workpiece having corners, and the robot moves along the guide rail to arc weld the workpiece, The welding torch is equipped with a movable part that moves in the direction of the welding line, A portable welding robot characterized in that the movable part controls the torch angle based on the torch angle calculated by the torch angle calculation unit.

10. A welding system comprising: a portable welding robot that moves along a guide rail to arc-weld a workpiece having corners; and a welding control device that controls the portable welding robot, The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device is A torch position determination unit for determining the torch position on the workpiece, A torch angle calculation unit that calculates the torch angle at the aforementioned torch position, It has, Position information of at least the workpiece and the guide rail is acquired based on at least one sensing means among touch sensing, laser sensing, and visual sensing. The torch position determination unit determines the torch position on the workpiece, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a straight section in a first region, A second region in which one of the positions of the portable welding robot on the guide rail and the position of the welding torch on the workpiece is in a straight section and the other is in a curved section, The position of the portable welding robot on the guide rail and the position of the welding torch on the workpiece are both in a third region located on a curved section, Divided into the following areas, The torch angle calculation unit calculates the torch angle at the torch position for each region based on at least the position information of the workpiece and the guide rail, A welding system characterized by controlling the torch angle by the movable part based on the calculated torch angle.

11. A method for controlling a portable welding robot using a welding system comprising: a portable welding robot that moves along a guide rail to arc-weld a polygonal rectangular steel pipe, and a welding control device that controls the portable welding robot, wherein the system includes: The portable welding robot has a welding torch and a movable part that moves the welding torch in the direction of the welding line. The welding control device is A torch position determination unit for determining the torch position on the polygonal rectangular steel pipe, A torch angle calculation unit that calculates the torch angle at the aforementioned torch position, It has, A step of acquiring positional information of at least the polygonal rectangular steel pipe and the guide rail based on at least one sensing means among touch sensing, laser sensing, and visual sensing, The steps include determining the torch position on the polygonal rectangular steel pipe using the torch position determination unit, The position of the portable welding robot on the guide rail and the position of the welding torch on the polygonal rectangular steel pipe are both in a first region that is in a straight section, A second region in which one of the positions of the portable welding robot on the guide rail and the position of the welding torch on the polygonal rectangular steel pipe is in a straight section and the other is in a curved section, The position of the portable welding robot on the guide rail and the position of the welding torch on the polygonal steel pipe are both in a third region located in a curved section, The step of dividing into these areas, The torch angle calculation unit calculates the torch angle at the torch position for each region based on the positional information of at least the polygonal rectangular steel pipe and the guide rail, A step of controlling the torch angle by the movable part based on the calculated torch angle, A control method for a portable welding robot, characterized by comprising the following:

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