Field welding apparatus and field welding method

Abstract

To provide an on-site welding apparatus and an on-site welding method which reduce a force acting on the welding apparatus from a weld bead in slag removal processing.SOLUTION: The on-site welding device 1 installed in the vicinity of a groove W of a steel-pipe column 3 in a construction site includes a welding tool 21 for performing welding of the groove W, a slag removing tool 27 for removing welding slag on a weld bead formed by the welding tool 21, and a robot arm 19 to which a plurality of types of tools 20 including the welding tool 21 and the slag removing tool 27 can be selectively mounted and which performs a moving operation of the mounted tool 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a field welding apparatus and a field welding method. [Background technology]

[0002] A conventional technique in this field is a welding device described in Patent Document 1 below. A welding tool and a slag removal tool can be selectively attached to the robot of this welding device, and the welding process for the target object is performed with the welding tool attached to the robot. Furthermore, since slag is generated on the weld bead formed during the welding process, a slag removal tool is attached to the robot to remove the slag from the weld bead. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3848808 Summary of the Invention [Problem to be solved by the invention]

[0004] During slag removal in this type of welding equipment, a slag removal tool comes into contact with the weld bead, and force may be applied from the weld bead to the welding equipment via the slag removal tool. This force may cause malfunctions in the welding equipment. Therefore, an object of the present invention is to provide a field welding equipment and field welding method that reduces the force applied from the weld bead to the welding equipment during slag removal. [Means for solving the problem]

[0005] The gist of the present invention lies in the following [1] to [7].

[0006] [1] An on-site welding device that is installed near a location to be welded on a steel frame at a construction site, the on-site welding device comprising: a welding tool that welds the location to be welded; a slag removal tool that removes welding slag on a weld bead formed by the welding tool; and a movement operation device that can selectively attach multiple types of tools including the welding tool and the slag removal tool and that moves the attached tools, wherein the slag removal tool has a removal tool tip that is brought into contact with the weld bead and an external force absorbing part that absorbs the force acting from the weld bead on the removal tool tip.

[0007] [2] The on-site welding device according to [1], wherein the moving operation device has a robot arm that can change the tool by its own operation using a tool change function.

[0008] [3] The on-site welding device according to [2], further comprising a robot arm control unit that controls the operation of the robot arm, wherein the robot arm control unit controls the robot arm to perform a welding process in which the welding tool is moved along a pre-planned welding path to weld the portion to be welded, and a slag removal process in which, after the welding process, the slag removal tool is moved to remove slag from the weld bead formed in the welding process, and wherein the movement path of the slag removal tool in the slag removal process is a path along the welding path.

[0009] [4] The on-site welding device according to [2] or [3], further comprising a rail installed near the steel frame, a carriage that carries the robot arm and moves on the rail, and a tool holder that can hold the replacement tool, wherein the tool holder is provided on the carriage.

[0010] [5] The on-site welding device according to [4], wherein the carriage is provided with a spatter guard that covers the side of the tool holder to be welded and protects the tool holder or the tool held in the tool holder from spatter generated at the welded portion, the tool is inserted into the tool holder by the robot arm obliquely downward with the tip side facing the steel frame, and the spatter guard has a plate material that is parallel to the insertion direction of the tool into the tool holder by the robot arm.

[0011] [6] The on-site welding device according to any one of [2] to [5], further comprising a robot arm control unit that controls the operation of the robot arm, wherein the robot arm control unit controls the robot arm to execute a welding process in which the welding tool is moved to weld the portion to be welded, a defective portion removal process in which, if an arc start failure occurs during the welding process, tool replacement is performed and the slag removal tool is moved to the portion where the arc start failure occurred to remove slag, and a return process in which tool replacement is performed and the welding process is returned to after the defective portion removal process.

[0012] [7] A field welding method performed using the field welding device according to any one of [2] to [5], comprising: a welding process in which the robot arm moves the welding tool to weld the portion to be welded; a defective portion removal process in which, if an arc start failure occurs during the welding process, the robot arm performs tool change, moves the slag removal tool to the portion where the arc start failure occurred, and removes slag; and a return process in which, after the defective portion removal process, the robot arm performs tool change and returns to the welding process. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a field welding device and a field welding method that reduce the force acting on the welding device from the weld bead during the slag removal process. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing a state in which the on-site welding device of this embodiment is installed on a column component to be welded. [Figure 2] FIG. [Figure 3] 1A is a perspective view of the slag removal tool, and FIG. 1B is a partial cross-sectional view of the slag removal tool as viewed from the side. [Figure 4] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit. [Figure 5] FIG. [Figure 6] 10(a) and 10(b) are diagrams illustrating the vicinity of the tool holder during the tool storing operation. [Figure 7] 10(a) and 10(b) are diagrams showing the vicinity of the tool holder during the tool mounting operation. [Figure 8] 7(a) and 7(b) are diagrams showing a state in which the configuration in the vicinity of the tool holder in FIG. 6 is modified. [Figure 9] 1 is a flowchart of a field welding method using a welding device. [Figure 10] 10 is a flowchart of an error process executed during a welding process. [Figure 11] FIG. 10 is a perspective view showing a state in which the on-site welding device according to the modified example is installed on a column part to be welded. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of a field welding apparatus and a field welding method according to the present invention will be described with reference to the drawings. In the following description, the same elements or elements having the same functions are designated by the same reference numerals, and redundant description may be omitted.

[0016] The welding device 1 shown in FIG. 1 is an on-site welding device for performing multi-layer welding of a steel pipe column 3 at a building construction site (construction site). The steel pipe column 3 is, for example, a rectangular steel pipe, and the steel pipe column 3 is constructed by stacking a plurality of rectangular column parts 3a in the vertical direction and welding them to each other. The column parts 3a, 3a to be welded are arranged so that their material axes are aligned and their horizontal ends are close to and face each other over the entire circumference. A groove W (welded part) is formed where these ends face each other, and the groove W extends in a horizontal plane over the entire circumference of the steel pipe column 3.

[0017] In the vicinity of the groove W, an erection piece 4 is welded in advance to each center of the four outer wall surfaces of the column parts 3a, 3a. The erection piece 4 provided on the upper column part 3a and the erection piece 4 provided on the lower column part 3a are aligned vertically and connected to each other by an erection jig 5 extending across the groove W. The column parts 3a, 3a before welding are temporarily connected to each other by a temporary connection part 7 including such erection pieces 4, 4 and the erection jig 5.

[0018] Welding device 1 includes rails 11, a welding robot 13 that can move on rails 11, and a control unit 15 that controls welding robot 13. Welding robot 13 includes a robot arm 19 and a carriage 17 that carries robot arm 19 and moves on rails 11.

[0019] (rails and carriages) The rail 11 forms a horizontal ring shape centered on the material axis of the steel pipe column 3, and is installed so as to surround the entire circumference of the steel pipe column 3. The rail 11 is supported by the lower column component 3a via a predetermined fixture 11a and is positioned lower than the groove W. The carriage 17 is slidably attached to the rail 11, carries a robot arm 19, and travels on the rail 11. The carriage 17 is equipped with a drive source (not shown) such as a motor for traveling on the rail 11, and the drive source operates in accordance with a control signal from the control unit 15.

[0020] (Robot arm) 2 is a side view of the welding robot 13. The robot arm 19 of the welding robot 13 is a six-axis vertical articulated robot arm. The robot arm 19 includes a base L0 (mounting) fixed to the mounting surface 17a of the carriage 17, a first link L1 rotatable about a first axis J1 relative to the base L0, a second link L2 rotatable about a second axis J2 relative to the first link L1, a third link L3 rotatable about a third axis J3 relative to the second link L2, a fourth link L4 rotatable about a fourth axis J4 relative to the third link L3, a fifth link L5 rotatable about a fifth axis J5 relative to the fourth link L4, and a distal link L6 rotatable about a sixth axis J6 relative to the fifth link L5. The axes J1, J4, and J6 are parallel to the plane of FIG. 2, and the axes J2, J3, and J5 are perpendicular to the plane of FIG. 2. The robot arm 19 is equipped with a motor (not shown) that rotates each of the links L1 to L6, and the motor operates according to a control signal from the control unit 15. The control unit 15 controls the rotation of each of the links L1 to L6, thereby controlling the position and posture of the tool 20.

[0021] The mounting seat 17a of the carriage 17 is inclined with respect to the vertical plane and parallel to the movement direction of the carriage 17. The first axis J1 (rotation axis) of the robot arm 19 attached to this mounting seat 17a is perpendicular to the mounting seat 17a and is inclined with respect to both the vertical direction and the horizontal plane. In other words, the first axis J1 is neither a vertical axis nor a horizontal axis. With this configuration, when the end effector at the tip of the robot arm 19 moves horizontally along the groove W, it is easy to adjust the movement range of the end effector to a suitable range within the movement range of the robot arm 19. In other words, it is easy to avoid a situation where the robot arm 19 operates near its movement limit, for example.

[0022] A plurality of types of tools 20 can be selectively attached to the tip 19a of the robot arm 19 (the tip of the distal end link L6) as an end effector. In the example shown in FIGS. 1 and 2, a welding tool 21 is attached to the tip 19a of the robot arm 19. Hereinafter, the tip 19a of the robot arm 19 will be simply referred to as the "arm tip 19a." The robot arm 19 has a tool change function and can replace the tool 20 attached to the arm tip 19a by its own movement. The tool changer 30 that realizes the tool change function is composed of a master coupler 31 attached to the arm tip 19a of the robot arm 19, tool couplers 33 attached to the rear ends of the respective tools 20, and a tool holder 35 attached to the carriage 17 for positioning and holding each replacement tool 20 at a predetermined position and orientation. Note that the tool holder 35 and a spatter guard 39 (described later) are not shown in FIG. 1.

[0023] Under the control of the control unit 15, the robot arm 19, which does not yet have the tool 20 attached thereto, moves its own arm tip 19a to abut the rear end of the tool 20 held in the tool holder 35, and couples the master coupler 31 with the tool coupler 33, thereby attaching the tool 20 to the arm tip 19a. This operation of the robot arm 19 to attach the tool 20 to the tool holder 35 is hereinafter referred to as the "tool attachment operation."

[0024] The robot arm 19, to which the tool 20 is attached, inserts the tool 20 attached to the arm tip 19a into the tool holder 35 at a predetermined position by its own operation under the control of the control unit 15, and releases the connection between the master coupler 31 and the tool coupler 33. This stores the tool 20 in the tool holder 35. The operation of the robot arm 19 to store the tool 20 in the tool holder 35 in this manner will be referred to below as the "tool storing operation."

[0025] According to the tool changer 30 as described above, the robot arm 19 performs the tool mounting operation and tool storage operation as described above in an appropriate combination under the control of the control unit 15, thereby realizing tool changes for the robot arm 19.

[0026] All tool holders 35 corresponding to the multiple tools 20 used by the robot arm 19 are mounted on the carriage 17. That is, when the carriage 17 moves along the rail 11, all tool holders 35 and tools 20 move together with the robot arm 19. Therefore, when changing tools as described above, there is no need to move the carriage 17 to retrieve the tools 20 from the tool holders 35, and the tool change can be performed simply by operating the robot arm 19. This makes it possible to shorten the cycle time of on-site welding.

[0027] The tools 20 used in the welding apparatus 1 of this embodiment include a welding tool 21 and a slag removal tool 27 (FIG. 3). In on-site welding using the welding apparatus 1, the robot arm 19 is fitted with the welding tool 21, performs welding of the groove W to form a weld bead in the groove W, and then the robot arm 19 is fitted with the slag removal tool 27 to remove welding slag from the weld bead. In this way, since the welding process and the slag removal process can be performed by a single robot arm 19, there is no need, for example, to install a robot arm for slag removal separately from the robot arm for the welding process.

[0028] (welding tools) The welding tool 21 is a tool for welding the groove W. A tool coupler 33 is provided at the rear end of the welding tool 21. The welding tool 21 is attached to the arm tip 19a of the robot arm 19 via the tool coupler 33 and the master coupler 31. A welding torch 21a for arc welding is provided at the tip side of the welding tool 21. A groove sensor 21b is also provided so as to protrude laterally from the welding torch 21a. The groove sensor 21b is a laser sensor that senses the cross section of the groove W. The groove sensor 21b is used, for example, to collect groove cross-sectional shapes for creating a welding pass plan and for feedback control of the target position of the welding torch 21a. In the welding process of the steel pipe column 3, under the control of the control unit 15, the robot arm 19 equipped with the welding tool 21 inserts the welding torch 21a into the groove W and forms a weld bead in the groove W while moving it in the longitudinal direction (horizontal direction) of the groove W. By repeatedly forming such weld beads, the weld beads are piled up in multiple layers and the groove W is welded.

[0029] (Slag removal tool) During the above welding process, slag is formed on the weld bead, and the slag removal tool is a tool for removing this slag from the weld bead. FIG. 3(a) is a perspective view of the slag removal tool 27, and FIG. 3(b) is a partial cross-sectional side view of the slag removal tool 27. Hereinafter, the X, Y, and Z directions are defined as shown in the figure, and X, Y, and Z may be used to describe the slag removal tool 27. The Z direction is the direction of the rotation axis J6 when the slag removal tool 27 rotates together with the link L6 (FIG. 2) of the robot arm 19. The Z direction is also the coupling direction between the tool coupler 33 and the master coupler 31. The X direction is perpendicular to the Z direction, and the Y direction is perpendicular to both the Z direction and the X direction.

[0030] The slag removal tool 27 includes a tool base 41, a chisel seat 42, a chisel gripper 43, and a chisel device 44. A tool coupler 33 is provided at the rear end of the tool base 41, and the tool base 41 is fixed to the arm tip 19a of the robot arm 19 via the tool coupler 33 and a master coupler 31 (FIG. 2). The chisel seat 42 is disposed adjacent to the tool base 41 in the Y direction and is fixed to the tool base 41 via a buffer part 45. The buffer part 45 is composed of two rubber members 45a, 45a arranged side by side in the Z direction. The rubber members 45a, 45a are sandwiched between the tool base 41 and the chisel seat 42, are positioned at the center in the X direction, and have a cylindrical or columnar shape with an axis in the Y direction. The rubber members 45a, 45a are made of hard rubber with a relatively high elastic modulus, and the chisel base 42 is fixed relatively firmly to the tool base 41 so as not to bend under its own weight. When the chisel base 42 is subjected to a relatively large external force, the two rubber members 45a, 45a elastically deform, causing the chisel base 42 to displace relative to the tool base 41. The number and arrangement of the rubber members 45a may be appropriately determined depending on the deformation characteristics required of the buffer 45, and the number of rubber members 45a may be one, three, or more. This buffer 45 allows the chisel base 42, the chisel gripping portion 43, and the chisel device 44 to displace in various directions relative to the tool base 41 while deforming the rubber members 45a, 45a.

[0031] The chisel gripping portion 43 is supported on the chisel base portion 42 so as to be slidable in the Z direction and is biased toward the tip side. As a specific structure, a rectangular guide hole 42a is formed in the center of the chisel base portion 42, and a guide shaft 42b extending in the Z direction is provided within the guide hole 42a. One end of the chisel gripping portion 43 in the Y direction is inserted into the guide hole 42a and engages with the guide shaft 42b. Because the Z direction dimension of the lower portion of the chisel gripping portion 43 is smaller than the guide hole 42a, the chisel gripping portion 43 can slide in the Z direction while being guided by the guide shaft 42b with a stroke corresponding to this dimensional difference. In addition, a compression spring 42c is installed on the rear end side of the guide hole 42a in a gap with the chisel gripping portion 43. The compression spring 42c biases the chisel gripping portion 43 in the Z direction toward the tip side, and this biasing force presses the chisel gripping portion 43 against the inner wall surface on the tip side of the guide hole 42a.

[0032] The chisel device 44 is held and fixed by the chisel gripper 43 at a position outside the guide hole 42a. The chisel device 44 is a device that applies a mechanical impact force to slag on the weld bead formed in the groove W to remove the slag. Such chisel devices 44 are sometimes called "air needle chisels" or "jet chisels." The chisel device 44 has a rod-shaped chisel portion 44a extending in the Z direction. During use, the tip 44b of the chisel portion 44a is abutted against the surface of the weld bead in the Z direction to apply an impact force, which removes the slag. The chisel portion 44a includes, for example, multiple needles that reciprocate at high speed in the Z direction, and the tips of these needles are collided with the slag to apply the impact force to the weld bead.

[0033] In the slag removal process, under the control of control unit 15, robot arm 19 equipped with slag removal tool 27 moves chisel tip 44b close to the surface of the weld bead in groove W, and then impacts a needle at chisel tip 44b against the weld bead surface, thereby removing slag from the weld bead. While removing the slag from the weld bead in this manner, robot arm 19 moves slag removal tool 27 in the longitudinal direction (horizontal direction) of the weld bead, thereby removing slag from the entire weld bead.

[0034] In the slag removal process described above, a reaction force in the Z direction, which causes the needle of the chisel tip 44b to collide with the weld bead, acts on the chisel 44a from the weld bead and then acts as an impact force on the robot arm 19 via the slag removal tool 27. Here, the welding device 1 is a device that performs welding on steel frames already installed at a construction site. For example, in this embodiment, the welding device 1 is used to add a new column component 3a onto a steel pipe column (lower column component 3a) already installed at the construction site. Therefore, the welding device 1 needs to be moved to each installed steel pipe column (lower column component 3a) existing at the construction site. For this reason, the welding device 1 is configured to be small and lightweight to ensure portability, and a small and lightweight robot arm 19 is also used. As a result, the impact of the reaction force described above on the robot arm 19 is relatively large, which may cause malfunctions of the robot arm 19.

[0035] Therefore, in order to absorb the Z-direction force acting on the chisel portion 44a from the weld bead, the slag removal tool 27 is equipped with an external force absorbing portion 47. The external force absorbing portion 47 is mainly composed of the chisel gripping portion 43, which is slidable in the Z-direction relative to the chisel base portion 42, and the compression spring 42c, which elastically supports the chisel gripping portion 43, which grips the chisel device 44, in the Z-direction. By interposing this external force absorbing portion 47 between the weld bead and the robot arm 19, the force acting on the chisel portion 44a from the weld bead is absorbed by the compression spring 42c, thereby reducing the Z-direction force transmitted to the robot arm 19. This makes it possible to suppress malfunctions of the robot arm 19 that may occur due to the above-mentioned reaction force.

[0036] Furthermore, because the weld bead has irregular projections and depressions, chisel portion 44a may be pressed by the weld bead as the weld bead moves in the longitudinal direction, causing a force in the Z direction to act on chisel portion 44a from the weld bead. Depending on the size of the weld bead's projections and depressions, this force may act as an impact force on robot arm 19. External force absorbing portion 47 can also absorb such forces.

[0037] Furthermore, during the slag removal process, for example, as the chisel portion 44a moves, the chisel portion tip 44b may catch on the unevenness of the weld bead, causing the chisel portion 44a to receive a force in the direction opposite to the direction of movement. Due to the irregular shape of the weld bead, a force in the XY plane may act on the chisel portion 44a from the weld bead, including this force. Therefore, to absorb such forces in the XY plane, the slag removal tool 27 further includes an external force absorbing portion 49. The external force absorbing portion 49 is configured with the buffer portion 45 described above.

[0038] According to the structure of the buffer unit 45 in which the two rubber members 45a, 45a are aligned in the Z direction as described above, the chisel device 44 can be displaced in the pitch direction (the rotational direction in the YZ plane) and the yaw direction (the rotational direction in the XZ plane). Therefore, the chisel unit 44a can absorb the force in the XY plane that is received from the weld bead, thereby reducing the force in the XY plane that acts on the robot arm 19. This reduces malfunctions of the robot arm 19 that may occur due to such forces. The external force absorbing unit 49 can also absorb the force in the Z direction that acts on the chisel unit 44a from the weld bead.

[0039] (Control unit 15) The control unit 15 is, for example, a computer system, and performs integrated control of the operation of the welding robot 13. The robot arm 19 of the welding robot 13 operates under the control of the control unit 15. That is, the control unit 15 controls the position and posture of the tool 20 attached to the arm tip 19a by controlling the motors that rotate each of the links L1 to L6 (FIG. 2) of the robot arm 19. This enables the robot arm 19 to move the tool 20 along the groove W and to attach and retract the tool when changing tools. The control unit 15 also controls the operation of the welding torch 21a itself, the operation of the groove sensor 21b itself, the operation of the chisel device 44 itself, and the coupling / releasing operation of the couplers when changing tools. The carriage 17 of the welding robot 13 moves on the rail 11 under the control of the control unit 15.

[0040] FIG. 4 illustrates an example of the hardware configuration of the control unit 15. Physically, the control unit 15 is configured as a computer system including a CPU 211, a main memory device (RAM 212 and ROM 213), a secondary memory device 215 such as a hard disk, an input device 216 such as a keyboard and a mouse, an output device 217 such as a display, and a communication module 214 for transmitting and receiving data to and from external devices such as the welding robot 13. The control unit 15 may be configured as a computer or the like, part of which may be built into the robot arm 19. Each of the hardware elements 211 to 217 does not necessarily reside within a single device. For example, the CPUs of multiple computers may cooperate to configure the CPU 211 of the control unit 15, and the RAMs of multiple computers may cooperate to configure the RAM 212 of the control unit 15. Furthermore, for example, elements built into the robot arm 19 may constitute part of the hardware elements 211 to 217.

[0041] The control of the operation of the robot arm 19, carriage 17, welding torch 21a, groove sensor 21b, and chisel device 44 by the control unit 15 as described above is performed by the control unit 15 executing a pre-set program, or by executing a program generated based on, for example, the measurement results of the groove shape by the groove sensor 21b, and sending and receiving control signals between the above-mentioned devices in accordance with the program.

[0042] (near the tool holder) The configuration near the tool holder 35 of the tool changer 30 described above will be described. FIG. 5 is a rear view of the welding robot 13, and the left-right direction in FIG. 5 corresponds to the extension direction of the rail 11 (the movement direction of the carriage 17). Generally, there are at least as many tool holders as there are tools used in the robot arm. In this embodiment, two tool holders 35, one for the welding tool 21 and one for the slag removal tool 27, are provided on the carriage 17, one on each side of the robot arm 19 in FIG. 5. The two tool holders 35 have a roughly symmetrical structure, so here we will describe the tool holder 35 located on the right side in FIG. 5, and will not repeat the description.

[0043] The tool holder 35 is supported by the carriage 17 via a predetermined steel member 37, and is fixed at a predetermined position and posture relative to the carriage 17. Therefore, the tool holder 35 moves horizontally together with the robot arm 19 in the extension direction of the rail 11 as the carriage 17 moves on the rail 11.

[0044] 6(a) and (b) are views showing the vicinity of the tool holder 35 during the tool storage operation, and FIGS. 7(a) and (b) are views showing the vicinity of the tool holder 35 during the tool attachment operation. FIGS. 6(a) and (b) and 7(a) and (b) are side views each showing a schematic view of the vicinity of the tool holder 35 as viewed from the direction of arrow VI in FIG. 5. The tool holder 35 is positioned lower than the groove W, and the groove W is located diagonally above the tool holder 35.

[0045] During tool replacement, the robot arm 19 performs a tool storage operation, storing the tool 20 in the tool holder 35. At this time, as shown in FIG. 6( a), the robot arm 19 inserts the tool 20 into the tool holder 35 in the direction of arrow A shown in the figure. The direction of arrow A is inclined, for example, at approximately 45° with respect to the horizontal plane and perpendicular to the coupling plane between the master coupler 31 and the tool coupler 33. Then, with the tool 20 held in the tool holder 35 by a predetermined positioning and holding mechanism, the master coupler 31 and the tool coupler 33 are released from coupling. As shown in FIG. 6( b), the robot arm 19 retreats in the direction opposite to arrow A (the direction of arrow A'), leaving the tool 20 on the tool holder 35. The tool 20 is positioned and held in the tool holder 35 with its tip facing the direction of arrow A, and waits until it is next used. That is, the tool 20 in the standby state is positioned and held in the tool holder 35 with its tip inserted diagonally downward, facing the steel pipe column 3. Furthermore, when the tool 20 is in a standby state, the tool coupler 33 provided on the tool 20 is located at a position lower than the groove W.

[0046] Furthermore, when a tool is replaced, the robot arm 19 performs a tool mounting operation, and mounts the tool 20 on the tool holder 35. At this time, as shown in FIG. 7( a), the arm tip 19a of the robot arm 19, without a tool mounted thereon, is brought closer to the tool 20 in the direction of arrow A shown in the figure. Then, the master coupler 31 of the arm tip 19a abuts against the tool coupler 33 of the tool 20, and the two are coupled together, thereby mounting the tool 20 on the robot arm 19. Then, as shown in FIG. 7( b), the robot arm 19 with the tool 20 mounted thereon retreats in the direction of arrow A', and the tool 20 is removed from the tool holder 35.

[0047] As described above, the arm tip 19a moves in the direction of arrow A (diagonally downward with the tip facing the steel pipe column 3) or the opposite direction of arrow A' during the tool storage operation and tool installation operation. It can be said that such movement of the arm tip 19a is within a suitable range of motion of the robot arm 19. Therefore, the robot arm 19 can smoothly change tools. Furthermore, since the standby tool 20 is held in the tool holder 35 in a state where it is inserted diagonally downward with the tip facing the steel pipe column 3 (inserted in the direction of arrow A), a holding structure is possible in which the standby tool 20 is caught by the tool holder 35 due to its own weight. Therefore, in the holding mechanism for the tool 20 in the tool holder 35, a mechanism for preventing the tool 20 from falling off due to its own weight can be omitted, thereby simplifying the holding mechanism.

[0048] (Spatter Guard) As described above, as shown in FIGS. 6 and 7, the tool holder 35 on the carriage 17 is positioned lower than the groove W. The upper surface 35a of the tool holder 35 faces diagonally upward. The tool coupler 33 of the tool 20 held by this tool holder 35 is also positioned lower than the groove W. The coupling surface 33a of the tool coupler 33 (the coupling surface with the master coupler 31) faces diagonally upward. The groove W is located within the reach of the robot arm 19 from the carriage 17. However, because the robot arm 19 is relatively small as described above, the distance between the carriage 17 and the groove W during the welding process is short. As a result, the groove W is located relatively close to and diagonally above the tool holder 35.

[0049] Due to the positional relationship described above, there is a possibility that spatter generated at the groove W during the welding process may fall on the tool holder 35 or the tool coupler 33 of the tool 20. Spatter falling on the tool holder 35 or the tool coupler 33 in this manner is undesirable because it may cause malfunctions in the tool changer 30. In particular, since the upper surface 35a of the tool holder 35 is provided with a positioning mechanism and a holding mechanism for the tool 20, spatter should be prevented from falling on this upper surface 35a. Furthermore, since various connection terminals for establishing mechanical and electrical connections with the master coupler 31 are also present on the coupling surface 33a, spatter should be prevented from falling on this coupling surface 33a.

[0050] Therefore, in the welding device 1, a spatter guard 39 is provided that covers the groove W side of the tool holder 35 to protect the tool holder 35 and the tool 20 from spatter. The spatter guard 39 is provided on the carriage 17, that is, is fixed to the carriage 17 via a predetermined steel material (not shown). The steel material used to attach the spatter guard 39 to the carriage 17 may be the same as the steel material 37 used to attach the tool holder 35 to the carriage 17.

[0051] The spatter guard 39 is made of a steel plate that extends parallel to the direction of arrow A across the space between the tool holder 35 and the groove W. Furthermore, by bending this steel plate, the spatter guard 39 includes a vertical flat portion 39b positioned between the tool holder 35 and the robot arm 19 and a flat portion 39a that is perpendicular to the flat portion 39b and positioned at an angle between the tool holder 35 and the robot arm 19. Both flat portions 39a and 39b are parallel to the direction of arrow A. Because the spatter guard 39 is made of a steel plate that is parallel to the direction of arrow A, interference between the tool 20 and the spatter guard 39 and between the robot arm 19 and the spatter guard 39 during tool replacement is avoided. In other words, during tool storage and tool installation operations, the tool 20 and the arm tip 19a of the robot arm 19 only need to move parallel to the spatter guard 39. Therefore, the spatter guard 39 is less likely to interfere with tool replacement by the robot arm 19.

[0052] If the extension direction of the spatter guard 39 and the insertion direction A of the tool 20 into the tool holder 35 were vertical, as shown in FIG. 8(a), spatter S would not be sufficiently prevented from falling on the tool holder 35 and tool 20 from above. In this case, even if the spatter guard 39 were repositioned vertically above the tool holder 35 as shown by the dashed line in FIG. 8(a), spatter S could be prevented, but this would interfere with tool change by the robot arm 19. It is also conceivable to move the spatter guard 39 between the solid-line position and the dashed-line position in FIG. 8(a), but this would complicate the device. Furthermore, if the extension direction of the spatter guard 39 and the insertion direction A of the tool 20 into the tool holder 35 were horizontal, as shown in FIG. 8(b), the arm tip 19a would need to move horizontally during tool change, making it difficult to change tools within the desired range of motion of the robot arm 19. Furthermore, as a holding structure for the tool holder 35 to hold the tool 20, it is difficult to adopt a structure in which the tool 20 is caught on the tool holder 35 by its own weight, and this may result in a complicated holding mechanism.

[0053] 6 and 7, in the welding device 1 of this embodiment, the above-mentioned problems can be avoided by tilting the direction in which the spatter guard 39 extends and the direction in which the tool 20 is inserted into the tool holder 35. That is, the fixed, simple spatter guard 39 that does not need to be driven can sufficiently prevent spatter S from falling on the tool holder 35 and the tool 20, and also enables smooth tool replacement by the robot arm 19.

[0054] In the welding apparatus 1 of this embodiment, the tool holder 35 is positioned lower than the groove W, and the tool coupler 33 of the tool 20 in a standby state in the tool holder 35 is also positioned lower than the groove W. With this arrangement, spatter S from the groove W is particularly likely to fall on the upper surface 35a of the tool holder 35 and the coupling surface 33a of the tool coupler 33, making the spatter guard 39 described above particularly useful. However, even if the tool holder 35 and the tool coupler 33 are positioned higher than the groove W, the spatter guard 39 is not necessarily unnecessary. In other words, some of the spatter S may fly upward from the groove W, potentially falling on the tool holder 35 and the tool coupler 33, which are positioned higher than the groove W. Therefore, the spatter guard 39 is useful in this case as well.

[0055] Next, a field welding method using the welding device 1 will be described. FIG. 9 is a flowchart of the field welding method using the welding device 1. As shown in the figure, the field welding method of this embodiment includes a welding step S100 and a slag removal step S150. The operations of the robot arm 19, carriage 17, welding torch 21a, groove sensor 21b, chisel device 44, etc., which will be described below, are all performed under the control of control unit 15.

[0056] The welding process S100 is a process of welding, for example, one layer of material within the groove W, and includes a groove scanning process S101, a welding pass planning process S103, and a welding execution process S105. The groove scanning process S101 is a process in which the robot arm 19 to which the welding tool 21 is attached moves the groove sensor 21b of the welding tool 21 along the groove W to scan the groove W and obtain information about the cross-sectional shape of the groove W. The welding pass planning process S103 is a process in which the control unit 15 performs calculations to create a welding pass plan based on the cross-sectional shape information obtained in the groove scanning process S101. The welding pass plan includes information about the welding path within the groove W (the path of movement of the tip of the welding torch 21a) in the welding execution process S105, and the like.

[0057] The welding execution step S105 is a step in which robot arm 19 executes the welding process based on the welding pass plan created in the welding pass planning step S103. In this welding execution step S105, robot arm 19 moves the tip of welding torch 21a along the welding path defined in the welding pass plan, thereby forming a weld bead on the welding path.

[0058] The slag removal process S150 is a process for removing slag from a weld bead of, for example, one weld layer formed in the welding process S100. The slag removal process S150 includes a slag removal path planning process S153 and a slag removal execution process S155. The slag removal path planning process S153 is a process in which the control unit 15 performs calculations to create a slag removal path plan. The slag removal path plan includes information on the slag removal path (the movement path of the chisel tip 44b) within the groove W in the slag removal execution process S155.

[0059] The slag removal execution step S155 is a step in which the robot arm 19 executes the slag removal process based on the slag removal path plan created in the slag removal path planning step S153. In this slag removal execution step S155, the robot arm 19 moves the chisel tip 44b along the slag removal path defined in the slag removal path plan, thereby removing slag on the weld bead while the chisel tip 44b comes into contact with the weld bead.

[0060] In the slag removal path planning step S153, the slag removal path is determined based on the welding path created in the welding path planning step S103. That is, the groove sensor 21b does not measure the shape of the weld bead prior to the slag removal path planning step S153. For example, the slag removal path determined here follows the welding path. The slag removal path may be the same as the welding path. Alternatively, the slag removal path may be a path to which additional elements have been added to the welding path. Examples of such additional elements include offsetting the slag removal path in the weld bead width direction, weaving the slag removal path in the weld bead width direction, or forming a spiral around the welding path. A combination of these additional elements may be added to the welding path. For example, the slag removal path may be a path that proceeds while oscillating at a position offset from the welding path. Furthermore, the additional elements to be added may vary for each weld bead. For example, since the weld beads of the top and bottom layers of the weld layer are adjacent to each column part 3a, the slag removal path may be offset toward the boundary part so that the chisel tip 44b can reach the vicinity of the boundary part with the column part 3a. Also, the slag removal path may be determined based on multiple welding passes included in the weld layer. For example, the slag removal path may be a path that passes through the center of two adjacent welding passes. In this case, slag removal processing is performed effectively near the valley between adjacent weld beads.

[0061] The additional elements of the slag removal path as described above may be included in the slag removal path itself, or may be added as a movement of the slag removal tool 27 in the slag removal execution step S155. That is, for example, the slag removal path determined in the slag removal path planning step S153 may be the same as the welding path, and in the slag removal execution step S155, a movement of the slag removal tool 27 that realizes the additional elements as described above may be added by the robot arm 19.

[0062] Since slag is particularly likely to remain at the longitudinal ends of the weld bead, a slag removal process may be performed to reduce the moving speed of slag removal tool 27 at the longitudinal ends of the weld bead.

[0063] The effects of the slag removal process S150 described above will be explained. As mentioned above, the robot arm 19 is relatively small. Therefore, to perform slag removal using a slag removal tool 27 small enough to be operated by the robot arm 19, it is necessary to precisely align the position of the chisel tip 44b with the weld bead and apply pinpoint impact. However, during on-site welding of steel frames at a construction site, the shape of the groove W is not constant, and therefore the position of the weld bead is also not constant. Therefore, the movement of the slag removal tool 27 cannot be performed by teaching. In contrast, according to the slag removal process S150 described above, the movement path of the chisel tip 44b in the slag removal execution process S155 follows the welding path. Therefore, the chisel tip 44b can be moved along the position of the weld bead throughout the entire area of ​​the weld bead formed in the welding process S100, allowing for effective slag removal.

[0064] Next, the error processing executed during the welding process S100 will be described with reference to FIG. 10 . This error processing prevents the welding process S100 from being stopped by automatically processing an arc start failure caused by slag during the welding execution process S105. Arc start failures are primarily caused by slag present in a welding layer below the welding layer to be welded or slag generated during welding of an adjacent pass on the same welding layer, such as slag that was not completely removed during the previous slag removal process S150. Arc start failures are likely to occur at the beginning of a welding pass, but are not limited thereto and can also occur midway or at the end of a welding pass.

[0065] As shown in FIG. 10 , when an arc start failure occurs during the welding process in the welding execution step S105 (S181), an arc start failure signal is input to the control unit 15 from the welding robot 13. This signal causes the control unit 15 to detect the arc start failure and temporarily halt the welding process (S183). The control unit 15 recognizes the location of the arc start failure based on the tip position of the welding torch 21a when the arc start failure occurred. In particular, if the arc start failure occurs at the start point of the welding process, the control unit 15 can recognize the location of the arc start failure based on the target position information of the start point in the welding pass plan. Then, the robot arm 19 performs a tool change, and the slag removal tool 27 is attached to the arm tip 19a (S185). Then, the robot arm 19 moves the chisel tip 44b to the location where the arc start failure occurred (S187) and brings the chisel tip 44b into contact with the weld bead at the location where the failure occurred.

[0066] Then, chisel device 44 is driven while chisel tip 44b is moved, for example, in a cross shape on the weld bead. This removes slag (defective area) at the location where the arc start failure occurred (S189). Robot arm 19 then performs tool change again, and welding tool 21 is again attached to arm tip 19a (S191). Robot arm 19 then returns the tip of welding torch 21a to the location where the arc start failure occurred, and returns to the welding process (S193), whereby the welding process is resumed.

[0067] According to the error processing in the field welding method of this embodiment, when an arc start failure occurs during the welding process, the robot arm 19 automatically removes the slag with the slag removal tool 27, and then automatically resumes the welding process. This automatically resolves the arc start failure, preventing the welding device 1 from frequently stopping due to the slag, thereby reducing the cycle time. Furthermore, removing the remaining slag as described above stabilizes the arc start and improves welding quality. Furthermore, the error processing described above can address not only arc start failures due to slag remaining after the previous slag removal step S150, but also arc start failures due to slag formed during the current welding step S100.

[0068] The present invention can be implemented in various forms, including the above-described embodiment, with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, it is also possible to configure modified forms by utilizing the technical matters described in the above-described embodiment. The configurations of the respective embodiments may be used in appropriate combination.

[0069] For example, in the welding device 1 in the embodiment, the welding robot 13 can move around the steel pipe pole 3 to be welded along the rail 11, but the welding device of the present invention may also be equipped with a welding robot 13 fixed to the steel pipe pole 3, as illustrated in Fig. 11, for example. Furthermore, the robot arm 19 equipped in the welding robot 13 is a six-axis vertical articulated robot arm, but is not limited to this. The present invention can also be applied when, instead of the robot arm 19, a linear robot or the like is used as a moving and operating device for moving and operating the tool 20.

[0070] Furthermore, in the field welding method of this embodiment, a single layer of welding is performed in the groove W in the welding step S100, and slag removal for that single layer is performed in the slag removal step S150. However, this is not limited to this. For example, one pass of welding may be performed in the welding step S100, and slag removal for that single pass may be performed in the slag removal step S150. Performing slag removal after each welding pass in this manner is believed to have the effect of improving the startability of the welding process and reducing slag entrapment. Compared to performing slag removal after each welding pass, performing slag removal after each welding layer is preferable in that it can shorten the cycle time.

[0071] Furthermore, in this embodiment, the slag removal step S150 is performed after the welding step S100, but the slag removal step S150 may also be performed before the welding step S100. In this case, the slag removal step S150 removes welding slag from the weld bead formed in the previous welding step S100. The movement path of the slag removal tool in this slag removal step S150 is determined based on the welding path of the previous welding step S100 and follows that welding path.

[0072] Furthermore, the welding apparatus of the present invention is not limited to welding square steel pipe columns 3 as described in the embodiment, but can also be applied to welding steel columns having any cross section, such as circular steel pipe columns or H-shaped columns. Furthermore, the welding apparatus of the present invention can be applied not only to welding steel columns, but also to welding various other steel frames. [Explanation of symbols]

[0073] 1...welding equipment (on-site welding equipment), 3...steel pipe column (steel frame), 3a...column part, 11...rail, 15...control unit (robot arm control unit), 17...carriage, 19...robot arm (movement operation device), 20...tool, 21...welding tool, 27...slag removal tool, 35...tool holder, 39...spatter guard, 44a...chisel part (tip of removal tool), 44b...chisel part tip, 47...external force absorbing part, 49...external force absorbing part, W...groove (area to be welded).

Claims

1. An on-site welding device installed near a portion to be welded of a steel frame at a construction site, a welding tool for welding the welded portion; a slag removal tool that removes welding slag on the weld bead formed by the welding tool; a movement operation device that can selectively mount a plurality of types of tools including the welding tool and the slag removal tool and moves the mounted tools; The slag removal tool a removal tool tip that is abutted against the weld bead; and an external force absorbing portion that absorbs the force acting on the tip of the removal tool from the weld bead.

2. The on-site welding device according to claim 1 , wherein the moving and operating device has a robot arm capable of changing the tool by its own operation using a tool change function.

3. Further, a robot arm control unit is provided to control the operation of the robot arm, The robot arm control unit a welding process in which the welding tool is moved along a pre-planned welding path to weld the welded portion; After the welding process, control the robot arm to perform a slag removal process in which the slag removal tool is moved to remove slag from the weld bead formed in the welding process; The field welding apparatus according to claim 2 , wherein a moving path of the slag removal tool in the slag removal process is a path along the welding path.

4. a rail installed near the steel frame; a carriage that carries the robot arm and moves on the rail; a tool holder capable of holding a replacement tool, The field welding apparatus of claim 2 , wherein the tool holder is mounted on the carriage.

5. the carriage is provided with a spatter guard that covers the side of the tool holder to be welded and protects the tool holder or the tool held by the tool holder from spatter generated at the welded portion, The tool is inserted into the tool holder by the robot arm obliquely downward with the tip side facing the steel frame, The field welding device according to claim 4 , wherein the spatter guard has a plate member that is parallel to a direction in which the robot arm inserts the tool into the tool holder.

6. Further, a robot arm control unit is provided to control the operation of the robot arm, The robot arm control unit a welding process in which the welding tool is moved to weld the welding portion; a defective portion removal process in which, when an arc start failure occurs during the welding process, a tool is replaced, the slag removal tool is moved to the portion where the arc start failure occurred, and slag is removed; 3. The field welding device according to claim 2, wherein the robot arm is controlled to execute a return process in which, after the defective portion removal process, a tool is replaced and the device is returned to the welding process.

7. A field welding method performed using the field welding apparatus according to claim 2, a welding process in which the robot arm moves the welding tool to weld the welding portion; a defective portion removal process in which, when an arc start failure occurs during the welding process, the robot arm performs a tool change and moves the slag removal tool to the portion where the arc start failure occurred, thereby removing slag; and a return process in which, after the defective portion removal process, the robot arm performs a tool change and returns to the welding process.

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