Portable welding robot control method and welding system

Abstract

To provide a control method for a portable welding robot to ensure good bead appearance even where a workpiece corner and a curved section of a guide rail are not located on concentric circles and where there is a large difference in curvature between the workpiece corner and the curved section of the guide rail.SOLUTION: A welding system comprises: a portable welding robot 100 which sets a guide rail with respect to a workpiece Wo having a corner and performs arc welding on the workpiece Wo while moving on the guide rail; and a welding control device 600 which controls the portable welding robot 100. The portable welding robot 100 has a welding torch 200 and a movable part that moves the welding torch 200 in a weld line direction. The control method comprises: determining a torch position on the workpiece Wo with a torch position determination unit 605; calculating a torch angle at the torch position with a torch angle calculation unit 606; and controlling the torch angle with the movable part based on 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 that can automatically perform welding while moving on a guide rail, and a welding system. [Background technology]

[0002] Conventionally, in the manufacture of welded structures such as shipbuilding, steel frames, and bridges, in-factory welding work 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 used, automation is progressing, moving from manual welding such as semi-automatic welding to welding methods that use lightweight, compact, portable welding robots that can be carried by a single worker. The application of such portable welding robots can improve welding efficiency at welding sites where welding has previously been performed manually.

[0003] Patent Document 1, for example, describes a technology that applies this portable welding robot. In Patent Document 1, a guide rail using a corner unit with straight and curved sections is attached to the outer periphery of a polygonal square steel pipe used at construction sites. A welding robot is then slidably mounted on the guide rail. When the center of curvature of the welded portion to be welded by the welding robot differs from the center of curvature of the corner unit where the welding robot is located when welding the portion, the control unit controls the movement speed of the welding robot so that the length of the welded portion per unit time (hereinafter also referred to as "bead length") by the welding robot is constant. This allows for efficient welding of square steel pipes of various shapes. The bead length per unit time by the welding robot is also referred to as the "welding speed." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-58078 Summary of the Invention [Problem to be solved by the invention]

[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 deposition rate even when the corner of the workpiece and the curved portion 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 portion of the rail are not concentric. In other words, the following phenomenon occurs. (1) When the robot is on a curved section of the rail and the tip of the torch is on a parallel section of the workpiece, the torch angle at the parallel section of the workpiece is the forward angle or the backward 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 a forward angle or a backward angle.

[0006] If the torch angle becomes a forward or backward angle, the following problems may occur, for example. (For forward angle) Spatters tend to be generated forward, which leads to deterioration of welding workability. (In the case of a sweepback angle) This pushes up the molten pool at the rear, resulting in the formation of a convex bead near the boundary between the corner and straight section on the workpiece, causing poor bead appearance. Furthermore, as the curvature of the corner of the workpiece becomes smaller and the difference in curvature with that of the rail becomes larger, the amount of change in the torch angle becomes larger, and the bead appearance at the boundary between the straight section and the corner becomes even worse.

[0007] Examples of workpieces with different curvature radii include roll-formed rectangular steel pipes (BCP) for building construction and roll-formed rectangular steel pipes (BCR) for building construction. The curvature radius of BCP is generally calculated as 3.5t relative to the plate thickness (t), while the curvature radius of BCR is 2.5t. In other words, for BCP and BCR with the same plate thickness, if the rail curvature radius is constant, the difference in curvature radius between the workpiece and the rail is larger for BCR. Therefore, BCR has a larger change in torch angle at the curved section of the rail relative to the workpiece, making it more likely to produce poor bead appearance at the boundary between the straight section and the corner.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its purpose 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 corner of the workpiece and the curved portion of the rail are not concentric and there is a large difference in curvature between the corner of the workpiece and the curved portion of the rail. [Means for solving the problem]

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

[0010] (A) A method for controlling a portable welding robot using a welding system including a guide rail installed for a workpiece having a corner, a portable welding robot that moves on the guide rail to arc-weld the workpiece, 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 a welding line direction; the welding control device includes a torch position determination unit that determines a torch position on the workpiece, and a torch angle calculation unit that calculates a torch angle at the torch position, determining a torch position on the workpiece by the torch position determination unit; calculating a torch angle at the torch position by the torch angle calculation unit; controlling the torch angle by the movable part based on the calculated torch angle; A method for controlling a portable welding robot, comprising:

[0011] The above object of the present invention is also achieved by the following configuration (B) relating to a welding control device.

[0012] (B) A welding control device for controlling a portable welding robot that installs a guide rail for a workpiece having a corner and moves on the guide rail to arc-weld the workpiece, a torch position determination unit that determines a torch position on the workpiece, and a torch angle calculation unit that calculates a torch angle at the torch position, the torch position determination unit determines the torch position on the workpiece, the torch angle calculation unit calculates a torch angle at the torch position, A welding control device characterized in that the torch angle is controlled based on the calculated torch angle.

[0013] The above object of the present invention is also achieved by the following configuration (C) relating to a portable welding robot.

[0014] (C) A portable welding robot controlled by the welding control device described above, which is provided with a guide rail for a workpiece having a corner, moves on the guide rail, and arc-welds the workpiece, a welding torch and a movable part that moves the welding torch in the direction of the welding line; The portable welding robot is characterized in that the movable part controls the torch angle based on the torch angle calculated by the torch angle calculation part.

[0015] The above object of the present invention is also achieved by the following configuration (D) of the welding system.

[0016] (D) A welding system including a portable welding robot that installs a guide rail for a workpiece having a corner, moves on the guide rail, and arc-welds the workpiece, 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 a welding line direction; the welding control device includes a torch position determination unit that determines a torch position on the workpiece, and a torch angle calculation unit that calculates a torch angle at the torch position, the torch position determination unit determines the torch position on the workpiece, the torch angle calculation unit calculates a torch angle at the torch position, A welding system characterized in that the torch angle is controlled by the movable part based on the calculated torch angle.

[0017] The above object of the present invention is also achieved by the following configuration (E) relating to a method for controlling a portable welding robot.

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

[0019] According to the control method for a portable welding robot of the present invention, 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, the torch angle can be controlled according to torch position information on the workpiece, thereby improving the bead appearance at the corner on the workpiece and at the boundary between the corner and the straight portion. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a welding system according to the present invention. [Figure 2] FIG. 2 is a schematic side view of the portable welding robot shown in FIG. [Figure 3] FIG. 3 is a perspective view of the portable welding robot shown in FIG. [Figure 4] FIG. 4 is a perspective view of the welding robot shown in FIG. 3 attached to a polygonal square steel pipe. [Figure 5] FIG. 5 is a diagram illustrating the positional relationship between the guide rail and the area of ​​the quarter corner of the polygonal square steel pipe when viewed from directly above in FIG. [Figure 6] FIG. 6 is a diagram of FIG. [Figure 7] FIG. 7 is a graph showing the relationship between the angle θ of the 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] FIG. 8 is a graph showing the relationship between the moving distance D of the portable welding robot and the torch angle correction amount θT. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a welding system according to an embodiment of the present invention will be described with reference to the drawings. Note that this embodiment is an example of a case in which a portable welding robot is used, and the welding system of the present invention is not limited to the configuration of this embodiment.

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

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

[0024] The control device 600 stores in advance information on the workpiece, information on the guide rail, and the workpiece W. o and a data storage unit 601 that stores 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, the welding conditions, the weaving operation, etc. Based on this teaching data, commands are sent to the portable welding robot 100 and the welding power source 400 to control the operation of the portable welding robot 100 and the welding conditions.

[0025] The control device 600 also includes a groove condition calculation unit 602 that calculates groove shape information from detection data obtained by touch sensing, visual sensors, or other sensors, and a welding condition calculation unit 603 that acquires welding conditions by correcting the welding conditions in the teaching data based on the groove shape information. The control device 600 also includes a speed control unit 604 that controls a drive unit (not shown) for driving the portable welding robot 100 in the X, Y, and Z directions (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 includes the groove condition calculation unit 602, welding condition calculation unit 603, speed control unit 604, torch position determination unit 605, and torch angle calculation unit 606. The torch position determination unit 605 and torch angle calculation unit 606 can also be integrated into 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. It may be divided into multiple parts based on their roles, such as a controller for teaching and a controller with other control functions. The control device 600 may be included within the portable welding robot 100, or it may be provided independently from the portable welding robot 100, as shown in FIG. 1 . That is, the welding system having the portable welding robot 100 and the control device 600 described in this embodiment includes both a case where the control device 600 is included within the portable welding robot 100 and a case where the control device 600 is provided independently from the portable welding robot 100. In this embodiment, signals are transmitted using the robot control cable 620 and the power supply control cable 630. However, this is not limited to this, and signals may be transmitted wirelessly. From the perspective of usability at a welding site, it is preferable to separate the control device into two parts: a controller for teaching and a controller with other control functions.

[0027] [Welding power source] The welding power source 400, in response to a command from the control device 600, connects the consumable electrode (hereinafter also referred to as "welding wire") 211 and the workpiece W. o By supplying power to the welding wire 211 and the workpiece W o An arc is generated between the welding wire 211 and the welding torch 200. Power from the welding power source 400 is sent to the wire feeder 300 via a power cable 410, and then sent from the wire feeder 300 to the welding torch 200 via a conduit tube 420. As shown in FIG. 2, the power is supplied to the welding wire 211 via a contact tip at the front end of the welding torch 200. The current used during welding may be either DC or AC, and the waveform is not particularly important. Therefore, the current may be a pulse such as a square wave or a triangular wave.

[0028] In addition, 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 W as a negative (-) electrode. o This is the case when welding with reverse polarity. When welding with positive polarity, the work W is connected via the positive (+) power cable. o The power supply 100 may be connected to the welding torch 200 side via a negative (-) power cable.

[0029] [Shielding gas supply source] Shielding gas supply source 500 is composed of a container filled with shielding gas and accessory components such as a valve. 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 inside welding torch 200, is guided by 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.

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

[0031] 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, and a protective tube that protects welding wire 211 is disposed inside the tube, and a flow path for shielding gas is formed. However, conduit tube 420 is not limited to this, and for example, a power supply cable and a hose for supplying shielding gas can be bundled around a protective tube that feeds welding wire 211 to welding torch 200. Also, for example, the tubes that feed welding wire 211 and shielding gas and the power cable can be installed separately.

[0032] [Portable welding robot] 2 and 3, the portable welding robot 100 includes a guide rail 120, a robot body 110 that is installed on the guide rail 120 and moves along the guide rail 120, and a torch connection unit 130 that is placed on the robot body 110. The robot body 110 is mainly composed of a housing unit 112 that is installed on the guide rail 120, a fixed arm unit 114 that is attached to the housing unit 112, and a movable arm unit 116 that is attached to the fixed arm unit 114 in a state that allows it to rotate in the direction of arrow R1.

[0033] Torch connector 130 is attached to movable arm 116 via crank 170, which is a movable part that moves welding torch 200 in the weld line direction, i.e., in the X direction. Torch connector 130 includes torch clamp 132 and torch clamp 134 that secure welding torch 200. In addition, housing 112 is provided with cable clamp 150 on the side opposite to the side where welding torch 200 is attached, for supporting conduit tube 420 that connects feeder 300 and welding torch 200.

[0034] In this embodiment, the workpiece W o and the welding wire 211, and the welding wire 211 is o By utilizing the voltage drop phenomenon that occurs when the workpiece W o The detection means is a touch sensor that senses the surface of the upper groove 10. The detection means is not limited to the touch sensor of this embodiment, and an image sensor, i.e., visual sensing or a laser sensor, i.e., laser sensing, or a combination of these detection means may be used, but it is preferable to use the touch sensor of this embodiment from the perspective of simplicity of the device configuration.

[0035] The housing 112 of the robot body 110 includes a robot drive unit (not shown) that drives the robot body 110 in a direction perpendicular to the plane of the paper, i.e., in the X direction in which the robot body 110 moves along the guide rail 120, as indicated by the arrow X in Fig. 2. The housing 112 can also be driven in the Z direction in which it moves in the depth direction of the groove 10, which is perpendicular to the X direction. The fixed arm 114 can also be driven relative to the housing 112 via the slide support 113 in the Y direction, which is the width direction of the groove 10, which is perpendicular to the X direction.

[0036] Furthermore, torch connector 130, to which welding torch 200 is attached, can be driven to swing back and forth in the X direction, i.e., in the direction of the weld line, by rotating crank 170 as shown by arrow R2 in Figure 3. Movable arm 116 is attached rotatably to fixed arm 114 as shown by arrow R1, and can be adjusted to an optimal angle and fixed.

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

[0038] With the above-described configuration, the tip of the welding torch 200 attached to the torch connecting part 130 can be directed in any direction. Furthermore, the robot body 110 can be driven on the guide rail 120 in the X direction in FIG. 2. The welding torch 200 can perform weaving welding by moving the robot body 110 in the X direction while reciprocating in the Y direction. Furthermore, by driving the crank 170, the welding torch 200 can be tilted depending on the construction situation, for example, by setting a forward angle or a backward angle. Furthermore, by tilting the welding torch 200 in the X direction by driving the crank 170, it is possible to weave the workpiece W, such as a polygonal square steel pipe, which will be described later. o This allows correction of a change in the torch angle, i.e., the forward or backward angle, that occurs when the curvature of the corner WC of the guide rail 120 differs from that of the curved portion 122 of the guide rail 120.

[0039] A mounting member 140 such as a magnet is provided below the guide rail 120. The guide rail 120 is supported by the mounting member 140 so that the workpiece W o The portable welding robot 100 is configured to be easily attached to and detached from the workpiece W. o When setting the portable welding robot 100 on the workpiece W, the operator grasps the handles 160 on both sides of the portable welding robot 100 and moves the portable welding robot 100 to the workpiece W. o It can be easily set on top.

[0040] <Torch angle control method> Next, a specific example of a method for controlling the torch angle when welding a polygonal square steel pipe using a portable welding robot traveling on a guide rail will be described. Fig. 4 is a perspective view of the portable welding robot 100 shown in Fig. 3 attached to the polygonal square steel pipe. As shown in Fig. 4, the guide rail 120 is arranged to guide the workpiece W. o The portable welding robot 100 is attached to the guide rail 120 along the circumferential direction of the outer surface of a polygonal square steel pipe. In this case, the guide rail 120 is provided so as to go around the outer surface of the steel pipe via the attachment member 140, and has a shape including a straight section 121 and a curved section 122. The portable welding robot 100 is attached to the guide rail 120 with the welding torch 200 facing downward. Figure 5 shows the polygonal square steel pipe W when viewed from directly above Figure 4. o 10 is a diagram illustrating the positional relationship with the guide rail 120 in the quarter corner area of ​​the guide rail 120. FIG.

[0041] 4 and 5, the guide rail 120 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. o has a straight line portion WL, a corner portion (curved portion) WC, and a boundary point WB between the straight line portion WL and the corner portion WC.

[0042] In this example, the radius of curvature RA of the curved portion 122 of the guide rail 120 is o The curvature radius of the corner WC is larger than RB, and the polygonal square steel pipe W o The corner WC of the guide rail 120 and the curved portion 122 of the guide rail 120 are not concentric. o The radius of curvature RB of the corner WC differs between the outer and inner circumferences, but as long as the total deposition amount is the same, in this example, it is set to the average value of the outer and inner circumferences.

[0043] As shown in FIG. 5, the radius of curvature RA of the curved portion 122 of the guide rail 120 is Aand the rail center R of guide rail 120 c The distance between the polygonal square steel pipe W and o The radius of curvature RB of the corner WC is the center of curvature O of the corner WC. B and polygonal square steel pipe W o Plate thickness center W c The distance is

[0044] The curvature radius RA of the curved portion 122 of the guide rail 120 and the polygonal square steel pipe W o The curvature radii RB of the corners WC are different (in this example, RA>RB), and they are not concentric. o In the welding area, the portable welding robot 100 is located on the straight section 121 of the guide rail 120, and the welding torch 200 is positioned on the polygonal square steel pipe W. o The first area I is located in the straight section WL of the guide rail 120, 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 square steel pipe W. o The second area II is located in the straight section WL of the guide rail 120, 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 square steel pipe W. o and a third region III located at the corner WC.

[0045] The portable welding robot 100 moves along the guide rail 120 based on the operation signal of the control device 600, and welds the polygonal square steel pipe W. o The guide rail 120 has a straight section 121, a curved section 122, and a boundary point 128, and 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. Examples of the position on the guide rail 120 include the straight section 121, the curved section 122, and the boundary point 128. The torch angle in the first region I is set to a value that is substantially constant regardless of the position of the portable welding robot 100 on the guide rail 120. o 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 the torch angle is not perpendicular to the polygonal square steel pipe W in the first region I. o It is preferable to control the torch angle to a substantially constant value with the torch angle at the straight portion WL as a reference.

[0046] Here, "a substantially constant torch angle" means that the torch angle is within a practically controllable angle range and that an angle error is allowed to an extent that the effect on welding quality is not a problem. 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, polygonal square steel pipe W o For example, when the welding torch 200 is at a right angle to the straight section WL of the polygonal square steel pipe W, that is, when the torch angle is 0°, the portable welding robot 100 moves counterclockwise from the lower right to the upper side on the straight section 121 of the guide rail 120. o Before reaching the corner WC, the robot reaches the curved portion 122 on the guide rail 120 and exits the first region I.

[0048] That is, the welding torch 200 of the portable welding robot 100 is o Even though the robot body 110 is positioned on the straight section WL of the guide rail 120, 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 becomes more forward or backward, causing a change in the torch angle. Because a change in the 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 determines the relationship between the guide rail 120 and the polygonal square steel pipe W that has been input to the control device 600 in advance. o Based on the information such as the size and shape of the torch, the torch angle deviation amount θ T(torch angle calculation step). The calculated amount of deviation in the torch angle is input to the control device 600 as a torch angle correction value, and the crank 170, which is the movable part, rotates as shown by arrow R2 in FIG. 3, thereby correcting the deviation in the torch angle (torch angle control step).

[0050] The position information input to the torch position determination unit 605 for determining the torch position is acquired by using a sensing function such as a laser sensor. o The size of the rail may be recognized by the control device 600, and the rail size may be manually input to the control device 600, or the teaching point position pre-stored in the data storage unit 601 may be obtained as position information.

[0051] Polygonal square steel pipe W at work site o The actual relative position of the guide rail 120 is determined by the polygonal square steel pipe W. o and manufacturing errors of the guide rail 120 and polygonal square steel pipe W o A misalignment may occur due to an installation error of the guide rail 120 relative to the workpiece W. For this reason, it is preferable that the torch position determination unit 605 makes a determination taking this misalignment into consideration. o It is preferable to obtain the position information of the guide rail 120 using a sensing function, as this eliminates the influence of misalignment. Note that the sensing function is not particularly important, and it is preferable to determine the torch position using at least one of touch sensing, laser sensing, and visual sensing, or a combination of these sensing methods.

[0052] The torch angle calculation unit 606 calculates the workpiece information, the guide rail information, and the workpiece W. o and calculates the torch angle based on the position information of the guide rail 120. This information may be information obtained by sensing or the like, or may be numerical data of each piece of information stored in advance in the data storage unit 601.

[0053] <How to calculate the torch angle> Next, a method for calculating the torch angle will be described in detail with reference to FIGS.

[0054] Here, the guide rail 120 is, for example, a guide rail 120 with RA=261 mm, and a polygonal square steel pipe W o We will explain an example in which BCR polygonal square steel pipes are used as examples. o There are BCR and BCP types, but both polygonal square steel pipes o However, the radius of curvature relative to the plate thickness is determined by standards.

[0055] FIG. 6 shows a guide rail 120 (rail) and a polygonal square steel pipe W o 10 is a diagram showing the area of ​​the quarter corner of the column, and the center line R of the guide rail 120 is c , and polygonal square steel pipe W o Center line W c As shown in FIG. 6, the center of curvature of the quadrant of the guide rail 120 is O A , the radius of curvature is RA, the polygonal square steel pipe W o The center of curvature of the quadrant at the corner of O B , the radius of curvature is RB, and the center of curvature is O. B The X coordinate of d1 is the center of curvature O B The Y coordinate of the robot 100 is d2. The portable welding robot 100 is positioned at point A on the guide rail 120, and the center of curvature O A The angle between the line segment LA connecting point A and the X axis is θ, and the center of curvature O B The angle between the line segment LB connecting point A and point B and the X axis is represented by θ1. o The second and fourth quadrants (not shown in FIG. 6) in which the straight line portion WL is a parallel straight line portion as shown in FIG. 5, are outside the scope of this description because the torch angle is 0° and does not change.

[0056] Assuming that the portable welding robot 100 moves counterclockwise from point A0 on the X axis, which corresponds to boundary point 128 in FIG. 5, the line segment LA intersects the polygonal square steel pipe W. oIn the section up to the boundary point B0 between the straight part WL and the corner part WC, that is, in the second region II, the torch angle correction amount θ T = θ, and the line segment LA is between point B0 and point B1, that is, in the third region III, the torch angle correction amount θ T =θ-θ1, and the torch angle correction amount θ in the second region II is the amount of correction after the line segment LA passes through the boundary point B1 between the corner portion WC and the straight line portion WL until it coincides with the Y axis. T =90°-θ.

[0057] Torch angle correction amount θ in the second region II T The torch angle correction amount θ in the third region III, where the line segment LA is between point B0 and point B1, i.e., 0≦θ1<90°, can be easily calculated if the angle θ between the line segment LA and the X axis is known. T This section provides details on:

[0058] In the third region III, the torch angle correction amount θ T = θ-θ1, so tanθ T =tan This can be converted as (θ-θ1)=(tanθ-tanθ1) / (1+tanθ×tanθ1). Therefore, it becomes as shown in equation (1). θ T =tan -1 (tanθ-tanθ1) / (1+tanθ×tanθ1)...(1)

[0059] Here, the XY coordinates of point A are (RAcosθ, RAsinθ), and are expressed as in equation (2). tanθ1=(RAsinθ-d2) / (RAcosθ-d1)...(2)

[0060] Substituting equation (2) into equation (1) gives 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 of 0≦θ1<90°.

[0061] Here, the radius of the guide rail 120 is RA = 261 mm, and the polygonal square steel pipe W o By substituting the radius RB = 62.5 mm, d1 = 40 mm, and d2 = 40 mm of the corner WC into equation (3), the angle θ and the torch angle correction amount θ are calculated. T The relationship can be found as shown in FIG.

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

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

[0064] This allows the workpiece W o The corner WC of the workpiece W and the curved portion 122 of the guide rail 120 are not concentric. o Even when there is a large difference in curvature between the corner WC and the curved portion 122 of the guide rail 120, welding can be performed at a substantially constant torch angle over the entire circumference of the weld, ensuring a good bead appearance.

[0065] (Other welding conditions) In order to maintain a substantially constant welding quality over the entire length of the weld, it is preferable that other welding conditions, including the torch angle, be substantially constant. Other welding conditions are as follows: the portable welding robot 100 is welding a polygonal square steel pipe W o Before the start of welding, the welding conditions during welding can be acquired using the robot body 110 that moves along the guide rail 120. That is, based on the operation signal of the control device 600, the robot body 110 is driven, the groove shape is automatically sensed by the touch sensor, the groove condition calculation unit 602 calculates groove shape information, and further based on the groove shape information and teaching data held by the data storage unit 601, the welding condition calculation unit 603 calculates the welding conditions. The groove shape information includes, for example, the groove shape, plate thickness, and start and end points, and the welding conditions include, for example, the welding current, arc voltage, tip-base metal distance, and welding speed. Note that, instead of automatically sensing the groove shape, welding may be performed based on teaching data of welding conditions that are set in advance for each teaching point position on the guide rail.

[0066] Torch position information can also be acquired from teaching point positions on the guide rail that are stored in advance in the data storage unit 601. Examples of torch position information include straight and curved sections of the guide rail, boundary points, and torch angle. This information may be acquired by a detection means such as an image sensor or a laser sensor, or a combination of these detection means.

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

[0068] That is, the robot velocity V o is the radius of curvature RA of the curved portion 122 of the guide rail 120 and the polygonal square steel pipe W o The ratio RA / RB of the curvature radius RB of the corner WC and the set robot speed V set in the straight section 121 c product V o =V c × (RA / RB). Speed ​​control unit 604 controls the robot speed of portable welding robot 100 based on the robot speed calculated by welding condition calculation unit 603.

[0069] In addition, in the second region II and the third region III, polygonal square steel pipe W o The heat input amount varies with the heat input amount in the first region I. Therefore, the welding conditions are controlled so that the heat input amounts in the second region II and the third region III are within a range of ±20% with respect to the heat input amount in the first region I. 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 that the polygonal square steel pipe W o The appearance of the joint at the straight portion WL and the corner portion WC is the same. The welding conditions referred to here include, for example, robot speed, welding current, welding voltage, and extension length, and are one or more conditions selected from these.

[0070] The present invention is not limited to the above-described embodiment, and modifications and improvements are possible as appropriate.

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

[0072] 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] Also, 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] Also, 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, calculating a torch angle at the torch position by the torch angle calculation unit; controlling the torch angle by the movable part based on the calculated torch angle; A method for controlling a portable welding robot, comprising: With this configuration, even when the corners of the workpiece and the curved portion of the guide rail are not concentric and there is a large difference in curvature between the corners of the workpiece and the curved portion of the guide rail, the torch angle can be controlled to an approximately constant angle to ensure a good bead appearance.

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

[0078] (3) A 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 work information, guide rail information, and position information of the work and the guide rail. With this configuration, it is possible to calculate the change in torch angle that occurs at the curved section of the guide rail, and by controlling the torch angle, it is possible to improve the bead appearance at straight sections, corners, and the boundary between corners and straight sections on the workpiece.

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

[0080] (5) The control method for a portable welding robot according to (4), characterized in that the control of the welding conditions includes controlling at least one of the welding current, arc voltage, tip-base metal distance, and robot movement speed. According to this configuration, it is possible to select optimum welding conditions for each welding position.

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

[0082] (7) A 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 at the torch position and the radius of curvature value at the curved portion of the guide rail. According to this configuration, the deviation angle of the torch angle at each welding position can be accurately calculated.

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

[0084] (9) A welding control device for controlling a portable welding robot that is provided with a guide rail for a workpiece having a corner and moves on the guide rail to arc-weld the workpiece, a torch position determination unit that determines a torch position on the workpiece, and a torch angle calculation unit that calculates a torch angle at the torch position, the torch position determination unit determines the torch position on the workpiece, the torch angle calculation unit calculates a torch angle at the torch position, A welding control device characterized in that the torch angle is controlled based on the calculated torch angle. With this configuration, even in areas where the corners of the workpiece and the curved portion of the guide rail are not concentric and there is a large difference in curvature between the corners of the workpiece and the curved portion of the guide rail, the torch angle can be maintained approximately constant, ensuring a good bead appearance.

[0085] (10) A portable welding robot controlled by the welding control device according to (9) above, which is configured to install a guide rail for a workpiece having a corner, and move on the guide rail to arc-weld the workpiece, a welding torch and a movable part that moves the welding torch in the direction of the welding line; The portable welding robot is characterized in that the movable part controls the torch angle based on the torch angle calculated by the torch angle calculation part. According to this configuration, the angular deviation of the torch angle at each welding position can be corrected by the movable part, and welding can be performed at a substantially constant torch angle.

[0086] (11) A welding system including a portable welding robot that is provided with a guide rail for a workpiece having a corner, moves on the guide rail, and arc-welds the workpiece, 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 a welding line direction; the welding control device includes a torch position determination unit that determines a torch position on the workpiece, and a torch angle calculation unit that calculates a torch angle at the torch position, the torch position determination unit determines the torch position on the workpiece, the torch angle calculation unit calculates a torch angle at the torch position, A welding system characterized in that the torch angle is controlled by the movable part based on the calculated torch angle. According to this configuration, the torch angle calculation unit calculates the angular deviation of the torch angle at each welding position, and the movable unit controls the torch angle to correct the angular deviation, thereby enabling welding to be performed at a substantially constant torch angle.

[0087] (12) A method for controlling a portable welding robot using a welding system including a guide rail installed for a polygonal square steel pipe, a portable welding robot that moves on the guide rail to arc-weld the polygonal square steel pipe, 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 a welding line direction; The welding control device has a torch position determination unit that determines a torch position on the polygonal square steel pipe, and a torch angle calculation unit that calculates a torch angle at the torch position, a step of determining a torch position on the polygonal square steel pipe by the torch position determination unit; calculating a torch angle at the torch position by the torch angle calculation unit; controlling the torch angle by the movable part based on the calculated torch angle; A method for controlling a portable welding robot, comprising: With this configuration, a portable welding robot installed on a guide rail can weld the entire circumference of the welded portion of a polygonal square 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 (guide rail) straight section 122 (guide rail) curved section 128 (guide rail) boundary point 170 Crank (moving 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 unit 606 Torch angle calculation unit d1 Center of curvature O B X coordinate of d2 Center of curvature O B Y coordinate of LA Center of curvature O A and the line segment connecting point A LB Center of curvature O B and the line segment connecting point A O A Center of curvature of curved section (of guide rail) O B Center of curvature of corner (of workpiece) RA: Radius of curvature at the curved section of the guide rail RB Radius of curvature at the corner of the workpiece W o Workpiece (polygonal square steel pipe) WL (Workpiece) Straight section WC (Workpiece) Corner (Curved) WB (Work) boundary point I 1st area II 2nd area III Third area θ The angle between the line segment LA and the X axis θ1 The angle between the line segment LB and the X axis θ T Torch angle correction amount

Claims

1. A method for controlling a portable welding robot using a welding system including a guide rail having a straight portion and a curved portion installed for a workpiece having a straight portion and a corner portion, a portable welding robot that moves on the guide rail to arc-weld the workpiece, 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 a welding line direction; the welding control device includes a torch position determination unit that determines a torch position on the workpiece based on a teaching point position on the guide rail and position information of the workpiece and the guide rail, and a torch angle calculation unit that calculates a torch angle at the torch position; The corners of the workpiece and the curved portions of the guide rail are not concentric, The center of curvature O of the curved portion of the guide rail Ａ Or the center of curvature O of the corner of the workpiece Ｂ determining a relationship between the corner of the workpiece and the curved portion of the guide rail based on the above; and determining a plurality of regions; a step of determining a torch position on the workpiece by the torch position determination unit from a teaching point position on the guide rail and position information of the workpiece and the guide rail; The torch angle calculation unit Workpiece information, guide rail information, and position information of the workpiece and the guide rail; a center of curvature O B of the corner portion of the workpiece or a center of curvature O A of the curved portion of the guide rail; Calculating the torch angle at the torch position based on controlling the torch angle by the movable part based on the calculated torch angle; and The teaching point position on the guide rail is set as the portable welding robot position on the guide rail, The torch angle is Depending on the region, an angle θ1 determined based on a line segment LB connecting the position of the portable welding robot on the guide rail and the center of curvature O B of the corner of the workpiece; an angle θ determined based on a line segment LA connecting the position of the portable welding robot on the guide rail and the center of curvature O A of the curved portion of the guide rail; The calculation is based on at least one angle of A control method for a portable welding robot, comprising:

2. Based on information about the workpiece and the guide rail obtained in a two-axis coordinate system, The angle θ1 is defined as the angle between the line segment LB and one of the two axes, The angle θ is the angle between the line segment LA and one of the two axial directions, the angle θ1 and the one axial direction that determines the angle θ are the same direction; 2. The method for controlling a portable welding robot according to claim 1,

3. In the step of determining a plurality of regions in the curved portion, a center of curvature O of the curved portion of the guide rail is Ａ The radius of curvature RA is determined based on the center of curvature O of the corner of the workpiece. Ｂ and a radius of curvature RB determined based on the above, and when RA>RB, the multiple regions are divided into region I where the portable welding robot is on a straight portion of the guide rail and the welding torch is on a straight portion of the workpiece, region II where the portable welding robot is on a curved portion of the guide rail and the welding torch is on a straight portion of the workpiece, and region III where the portable welding robot is on the curved portion of the guide rail and the welding torch is on a corner of the workpiece; 2. The method for controlling a portable welding robot according to claim 1,

4. the welding control device includes a welding condition calculation unit, At the torch position, the torch angle is controlled and welding conditions are controlled; The welding conditions include controlling at least one of a welding current, an arc voltage, a tip-base metal distance, and a robot moving speed; 2. The method for controlling a portable welding robot according to claim 1,

5. a torch angle when the portable welding robot is on the straight portion of the guide rail and the welding torch is on the straight portion of the workpiece is used as a reference; controlling the direction of the torch angle toward the forward angle side or the backward angle side so that the torch angle at the straight portion and the corner portion of the workpiece is substantially constant at the reference angle; 2. The method for controlling a portable welding robot according to claim 1,

6. The torch angle serving as the reference angle is perpendicular to the workpiece, The torch angle at the straight portion and corner portion of the workpiece is set to be approximately constant at an angle perpendicular to the workpiece.

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

7. A welding system comprising: a guide rail having a straight portion and a curved portion installed for a workpiece having a straight portion and a corner portion; a portable welding robot that moves on the guide rail to arc-weld the workpiece; 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 a welding line direction; the welding control device includes a torch position determination unit that determines a torch position on the workpiece based on a teaching point position on the guide rail and position information of the workpiece and the guide rail, and a torch angle calculation unit that calculates a torch angle at the torch position; The corners of the workpiece and the curved portions of the guide rail are not concentric, The center of curvature O of the curved portion of the guide rail Ａ Or the center of curvature O of the corner of the workpiece Ｂ Based on the above, a relationship between the corners of the workpiece and the curved portions of the guide rail is determined, and a plurality of regions are determined; the torch position determination unit determines a torch position on the workpiece from a teaching point position on the guide rail and position information of the workpiece and the guide rail; The torch angle calculation unit Workpiece information, guide rail information, and position information of the workpiece and the guide rail; a center of curvature O B of the corner portion of the workpiece or a center of curvature O A of the curved portion of the guide rail; Calculating the torch angle at the torch position based on controlling the torch angle by the movable part based on the calculated torch angle; The teaching point position on the guide rail is set as the portable welding robot position on the guide rail, The torch angle is Depending on the region, an angle θ1 determined based on a line segment LB connecting the position of the portable welding robot on the guide rail and the center of curvature O B of the corner of the workpiece; an angle θ determined based on a line segment LA connecting the position of the portable welding robot on the guide rail and the center of curvature O A of the curved portion of the guide rail; The calculation is based on at least one angle of A welding system comprising:

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