Welding method and welding equipment

Abstract

To provide a welding method and a welding apparatus which can execute welding of a groove in such a state that there is no actual measurement information of the groove in a non-welded state.SOLUTION: A welding method comprises: a sensing step of acquiring a contour line 51 of a remaining cross section 55 that is left without being welded in a groove W by a groove sensor 23 of a welding robot 13; a cross section estimation step of estimating a shape of the remaining cross section 55 on the basis of the contour line 51 and calculating an estimated remaining cross section 56; a target position setting step of setting a target position L in the estimated remaining cross section 56 on the basis of the estimated remaining cross section 56; and a welding step of forming a weld bead H in the remaining cross section 55 with a welding tool 21 by the welding robot 13 aiming at the target position K. In the cross section estimation step, the estimated remaining cross section 56 is calculated without using information measured for the cross section of the groove W in the non-welded state.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] A conventional welding method described in Patent Document 1 is known as a technology in this field. In this welding method, groove information is acquired by a groove sensor of a welding robot, and multiple welding passes for the groove are planned based on the acquired groove information. Then, welding processes are repeatedly performed using the welding tool of the welding robot based on the plan, and welding of the groove progresses. While performing the above welding process, the welding robot acquires groove information using the groove sensor and adjusts the position of the welding tool. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-28522 Summary of the Invention [Problem to be solved by the invention]

[0004] The above welding method is based on the premise that welding is started from an unwelded groove state. However, in this type of welding method, there are situations where it is desired to start welding from a state where the groove has already been partially welded, and in such cases, groove information for the unwelded state does not necessarily exist. The present invention aims to provide a welding method and welding device that can perform welding of the groove without actual measurement information of the unwelded groove. [Means for solving the problem]

[0005] The gist of the present invention is as follows.

[0006] [1] A welding method for performing multi-layer welding on a groove of a workpiece using a welding robot having a welding end effector and a sensor, the method comprising: a sensing step in which, when a pre-welded portion of a predetermined thickness is present in the groove, the sensor of the welding robot senses the vicinity of the groove and acquires a contour line of a remaining cross-section, which is a cross-section of a portion of the groove that remains unwelded; a cross-section estimation step in which the shape of the remaining cross-section is estimated based on the contour line obtained in the sensing step to calculate an estimated remaining cross-section; a target position setting step in which the end effector is set to aim at the target position set in the target position setting step, and the welding robot forms a weld bead in the remaining cross-section with the end effector; and in the cross-section estimation step, the estimated remaining cross-section is calculated without using information actually measured about the cross-section of the groove in an unwelded state before the pre-welded portion is formed.

[0007] [2] The welding method according to [1], wherein the estimated remaining cross section is a quadrilateral ABCD having vertices at points A and D, respectively corresponding to two corners formed by the intersection of the surface of the workpiece and the inner surface of the groove, and points B and C estimated as points on the two inner surfaces, and in the cross section estimation process, two inflection points detected from the contour line obtained in the sensing process are defined as points A and D, respectively, a vector AL is defined along a linear contour portion of the contour line starting from point A, and a vector DL ​​is defined along a linear contour portion of the contour line starting from point D, and point B is defined on an extension line of vector AL and point C is defined on an extension line of vector DL ​​based on the thickness of the previously welded portion and the design depth of the groove in an unwelded state before the previously welded portion is formed.

[0008] [3] A welding method according to [1] or [2], in which the sensing process and the welding process are carried out with the welding robot being installed on a rail installed around the steel pipe column, which is the object to be welded, and capable of moving on the rail.

[0009] [4] A welding method according to any one of [1] to [3], further comprising: a temporary welding process in which the steel pipe columns are temporarily connected vertically via temporary connection parts including erection pieces and erection jigs, and the already-welded portion is formed in the groove by a welding method that does not use the welding robot; a temporary connection removal process in which the temporary connection part is removed after the temporary welding process; and a robot installation process in which the rail is installed around the steel pipe column after the temporary connection removal process and before the sensing process, and the welding robot is installed on the rail.

[0010] [5] A welding device that performs multi-layer welding on a groove of an object to be welded, comprising a welding robot having a welding end effector and a sensor, and a control unit that controls the welding robot, the end effector, and the sensor. The control unit causes the sensor of the welding robot to sense the vicinity of the groove when a welded portion of a predetermined thickness exists in the groove, and acquires a contour line of a remaining cross section, which is a cross section of a portion of the groove that remains unwelded. A sensing processing control unit that acquires a contour line of the remaining cross section, which is a cross section of a portion of the groove that remains unwelded, based on the contour line obtained by the sensing processing control unit. a target position setting unit that sets a target position for the end effector within the estimated remaining cross section based on the estimated remaining cross section obtained by the cross section estimation unit; and a welding process control unit that causes the welding robot to form a weld bead within the remaining cross section with the end effector, aiming at the target position set by the target position setting unit, wherein the cross section estimation unit calculates the estimated remaining cross section without using information actually measured about the cross section of the groove in an unwelded state before the welded portion is formed. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a welding method and a welding device that are capable of welding a groove in an unwelded state without actual measurement information of the groove. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a welding device according to an embodiment; [Figure 2] FIG. 2 is a side view of a welding robot provided in the welding device of the present embodiment. [Figure 3] FIG. 2 is a block diagram of a control unit included in the welding device of the present embodiment. [Figure 4] 2 is a flowchart of a welding method according to the present embodiment. [Figure 5] 4(a) and 4(b) are cross-sectional views of the vicinity of the groove in the welding method of the present embodiment. [Figure 6] 4(a) and 4(b) are cross-sectional views of the vicinity of the groove in the welding method of the present embodiment. [Figure 7] 1A is a cross-sectional view showing a remaining cross section of the groove, and FIG. 1B is a cross-sectional view showing an estimated remaining cross section of the groove. [Figure 8] FIG. 10(a) is a cross-sectional view illustrating a target position setting step, and FIG. 10(b) is a cross-sectional view illustrating a welding step. [Figure 9] 10 is a flowchart of a calculation process by a cross-section estimation unit for setting an estimated remaining cross-section. [Figure 10] 10(a) to 10(d) are cross-sectional views illustrating the calculation process performed by a cross-section estimation unit for setting an estimated remaining cross-section. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a welding method and a welding apparatus 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.

[0014] The welding device 1 shown in FIG. 1 is an on-site welding device for performing multi-layer welding of column components 3 at a building construction site. The column components 3 are, for example, square steel pipes, and a plurality of column components 3 are stacked vertically and welded to each other to construct a square steel pipe column. The column components 3, 3 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 is formed where these ends face each other, and the groove W extends in a horizontal plane over the entire circumference of the column component 3.

[0015] 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 3, 3. The erection piece 4 provided on the upper column part 3 and the erection piece 4 provided on the lower column part 3 are aligned vertically and connected to each other by an erection jig 5 extending across the groove W. The column parts 3, 3 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.

[0016] The welding device 1 includes a rail 11, a welding robot 13 that can move on the rail 11, and a control unit 15 that controls the welding robot 13.

[0017] (rail) The rail 11 has an annular shape centered on the material axis of the column parts 3, 3, and is installed so as to surround the entire circumference of the column parts 3, 3. The rail 11 is supported by the column part 3 on the lower side via a predetermined fixture 11a and is placed at a position slightly lower than the groove W. A carriage 17 is slidably attached to the rail 11, and the carriage 17 carries the welding robot 13 and travels on the rail 11.

[0018] (welding robot) 2 is a side view of welding robot 13. Welding robot 13 is a six-axis vertical articulated robot. Arm 13a of welding robot 13 includes a base L0 (mounting base) fixed to mounting surface 17a of carriage 17, a first link L1 rotatable about a first axis J1 relative to base L0, a second link L2 rotatable about a second axis J2 relative to first link L1, a third link L3 rotatable about a third axis J3 relative to second link L2, a fourth link L4 rotatable about a fourth axis J4 relative to third link L3, a fifth link L5 rotatable about a fifth axis J5 relative to fourth link L4, and a distal link L6 rotatable about a sixth axis J6 relative to fifth link L5. Note that the above-mentioned 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 welding robot 13 is provided with a drive source (not shown) such as a motor that rotates each of the links L1 to L6.

[0019] The mounting seat 17a of the carriage 17 is inclined with respect to the vertical plane and parallel to the direction of movement of the carriage 17. The first axis J1 (rotation axis) of the welding robot 13 attached to the mounting seat 17a is perpendicular to the mounting seat 17a and 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 arm 13a 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 welding robot 13. In other words, it is easy to avoid a situation where the welding robot 13 operates near the movement limit of the arm 13a, for example.

[0020] A welding tool 21 serving as a welding end effector is mounted on the tip (foremost link L6) of the arm 13a of the welding robot 13. For example, a welding torch for arc welding or a laser head for laser welding may be used as the welding tool 21, but the welding tool 21 in this embodiment is a welding torch for arc welding. Furthermore, a groove sensor 23 for acquiring information about the groove W is mounted on the tip of the arm 13a of the welding robot 13. The groove sensor 23 is, for example, a laser sensor that senses the cross section of the groove W. The groove sensor 23 is fixed to the welding tool 21 via a predetermined mounting jig so as to protrude laterally from the welding tool 21.

[0021] (Control unit) Control unit 15 is a computer system that comprehensively controls the movement of welding robot 13 on rail 11 (travel of carriage 17), the drive of arm 13a of welding robot 13, the welding operation of welding tool 21, the sensing operation of groove sensor 23, etc. Control unit 15 controls the rotation of each of links L1 to L6, thereby controlling the position and posture of welding tool 21 and groove sensor 23.

[0022] Fig. 3 is a block diagram showing the functional configuration of control unit 15. As shown in Fig. 3, control unit 15 has, as its functional configuration (hereinafter referred to as "functional modules"), a storage unit 27 that stores information, a calculation unit 29 that performs various calculations, a sensing process control unit 31 that performs sensing processes, and a welding process control unit 33 that performs welding processes. Calculation unit 29 has a cross-section estimation unit 29a and a target position setting unit 29b.

[0023] These functional modules merely divide the functions of the control unit 15 into multiple modules for convenience, and do not necessarily mean that the hardware constituting the control unit 15 is divided into such modules. For example, the hardware constituting the control unit 15 may be composed of multiple control computers, and each functional module may be realized by combining the functions of the multiple control computers. Each functional module may be realized by the control computer executing a computer program, or may be realized by a dedicated electric circuit (e.g., a logic circuit) or an integrated circuit (ASIC: Application Specific Integrated Circuit) that integrates such a circuit.

[0024] The sensing process control unit 31 controls the operation of the welding robot 13 and also controls the operation of the groove sensor 23, and causes the welding robot 13 and the groove sensor 23 to cooperate to perform sensing processing to acquire information about the groove W (hereinafter, "groove information"). Specifically, the sensing process control unit 31 moves the groove sensor 23 along the groove W by the operation of the welding robot 13, while the groove sensor 23 scans the vicinity of the groove W to acquire groove information in each cross section at a predetermined pitch (for example, 50 mm pitch). The acquired groove information is stored in the memory unit 27. This groove information includes information about the contour line of the cross section near the groove W at each position of the groove W.

[0025] The operation of welding robot 13 controlled by sensing process control unit 31 includes the movement of welding robot 13 on rail 11 (travel of carriage 17) and the driving of arm 13a of welding robot 13, but the sensing process is preferably performed while welding robot 13 is stopped from moving on rail 11. In this case, groove sensor 23 is moved only by the movement of arm 13a of welding robot 13, so the positional accuracy of groove sensor 23 during scanning is high, and as a result, the accuracy of the acquired groove information is also high.

[0026] Welding process control unit 33 controls the operation of welding robot 13 and also controls the operation of welding tool 21, and executes a welding process in which welding robot 13 and welding tool 21 cooperate to perform welding within groove W. Specifically, welding process control unit 33 causes welding robot 13 to move welding tool 21 along groove W in the extension direction of groove W, while welding tool 21 forms a weld bead within groove W. At this time, welding process control unit 33 controls the ON / OFF of welding tool 21 and the welding state of welding tool 21 (for example, the welding current value and the feed rate of filler metal).

[0027] The operations of welding robot 13 controlled by welding process control unit 33 include the movement of welding robot 13 on rail 11 (travel of carriage 17) and the driving of arm 13a of welding robot 13, but it is preferable that the above welding process be performed with welding robot 13 stopped from moving on rail 11. In this case, welding tool 21 is moved only by the operation of arm 13a of welding robot 13, so the positional accuracy of welding tool 21 during welding is high, and as a result, the welding accuracy is also high.

[0028] (Welding method) Next, details of the welding method for the column parts 3, 3 performed using the above-mentioned welding device 1 will be described with reference to FIGS. 4 to 8. Hereinafter, when distinguishing between the column parts 3, 3 to be welded to each other, the existing column part 3 will be referred to as the "column part 3A", and the column part 3 connected above it will be referred to as the "column part 3B". The welding method of this embodiment is a welding method for performing multi-layer welding on the groove W, and as shown in the flowchart of FIG. 4, it includes a temporary welding process S102, a temporary connection removal process S104, a robot installation process S106, a sensing process S108, a cross-section estimation process S110, a target position setting process S112, and a welding process S114.

[0029] [Initial state] FIG. 5(a) is a cross-sectional view showing the vicinity of the groove W in the initial state before the welding method of this embodiment is performed. As shown in the figure, the column part 3A and the column part 3B are temporarily connected via a temporary connection part 7 including the erection pieces 4, 4 and the erection jig 5. The upper end surface 41 of the column part 3A is formed as a substantially horizontal plane, and the lower end surface 42 of the column part 3B is formed as an inclined plane. The upper end surface 41 and the lower end surface 42 are arranged so as to face each other vertically at a predetermined interval, and a backing metal 6 is provided across the inner wall surface of the column part 3A and the inner wall surface of the column part 3B to seal the gap between them. The groove W thus formed between the column part 3A and the column part 3B forms a trapezoidal cross-sectional groove extending horizontally to a depth equal to the wall thickness of the column parts 3A and 3B. The inner surface 49 of the groove W is defined by the upper end surface 41 of the column part 3A, the lower end surface 42 of the column part 3B, and the surface 40 of the backing metal fitting 6 provided on the inner wall surfaces of the column parts 3A and 3B. In addition, the rail 11 (Fig. 1) has not yet been attached to the column part 3A, and the welding robot 13 (Fig. 1) has not yet been installed. The groove W is in an unwelded state.

[0030] [Temporary welding process S102] From the above initial state, as shown in FIG. 5(b), tack welding is performed on the bottom of the groove W (on the backing metal 6 side). Specifically, about two layers of weld beads are formed on the surface 40 of the backing metal 6, including the corner 45 between the upper end surface 41 of the column component 3A and the surface 40 of the backing metal 6, and the corner 46 between the lower end surface 42 of the column component 3B and the surface 40 of the backing metal 6, and the column component 3A and the column component 3B are tack-welded. Since the rail 11 and the welding robot 13 have not yet been installed, this tack-welding process is naturally performed by a welding method that does not use the welding robot 13. For example, in this embodiment, the tack-welding process is performed by manual welding by a worker. As a result, a welded portion 91 with a thickness of about two layers of weld beads is formed at the bottom of the groove W.

[0031] [Temporary connection removal step S104] After the above-mentioned temporary welding process S102, the temporary connection part 7 is removed. Specifically, the erection jig 5 is removed, the erection piece 4 on the surface 43 of the column part 3A is removed by thermal cutting, and the erection piece 4 on the surface 44 of the column part 3B is removed by thermal cutting. As a result, the temporary connection between the column part 3B and the column part 3A via the temporary connection part 7 is released, but as shown in FIG. 6(a), the column part 3A can sufficiently support the column part 3B by temporary welding using the already welded part 91.

[0032] [Robot installation process S106] After the temporary connection removing step S104, a rail 11 (FIG. 1) is installed around the pillar parts 3A and 3B. Here, the rail 11 is attached to the pillar part 3A via a fixture 11a. Then, a carriage 17 and a welding robot 13 (FIG. 1) are installed on the rail 11. The welding device 1 becomes usable by the robot installation step S106.

[0033] [Sensing step S108] From this sensing step S108 onwards, each step is performed using the welding device 1 that has become available. In the sensing step S108, as shown in FIG. 6(b), the groove W is sensed by the groove sensor 23 of the welding robot 13, and the contour line of the cross section near the groove W is acquired. Specifically, the sensing process control unit 31 (FIG. 3) of the control unit 15 moves the groove sensor 23 along the groove W by the operation of the welding robot 13, while the groove sensor 23 scans the vicinity of the groove W to acquire groove information at each cross section. Here, a contour line 51 of the cross section near the groove W is acquired for each cross section at a predetermined pitch (for example, 50 mm pitch) of the groove W. The contour line 51 includes the contour of a part of the surface 44 of the column component 3B, the contour of the lower end face 42 of the column component 3B, the contour of the surface 92 of the already welded portion 91, the contour of the upper end face 41 of the column component 3A, and the contour of a part of the surface 43 of the column component 3A.

[0034] As shown in FIG. 6(b), groove sensor 23 may sense groove W not necessarily in a horizontal position but at a predetermined depression angle θ. In this case, the position coordinates of each point on contour line 51 are corrected based on the depression angle θ. In addition, in this sensing step S108, the horizontal distance of groove sensor 23 from groove W may be adjusted based on the design thickness of already welded portion 91. In this case, the camera provided in groove sensor 23 can be well focused on the required portion (for example, surface 92 of already welded portion 91).

[0035] [Cross section estimation process S110] In the cross-section estimation step S110, for each cross-section of the groove W at a predetermined pitch (e.g., 50 mm pitch), the shape of the remaining cross-section 55 of the groove W is estimated based on the contour line 51 obtained in the sensing step S108, and an estimated remaining cross-section is calculated. Here, the remaining cross-section 55 refers to the cross-section that remains in the groove W at the present time, as shown in FIG. 7(a). In other words, it refers to the cross-section of the portion of the groove W that remains unwelded. For example, in this case, the remaining cross-section 55 is the cross-section of the groove W in an unwelded state (see FIG. 5(a)) minus the cross-section of the welded portion 91 (see FIG. 5(b)). In this cross-section estimation step S110, the cross-section estimation unit 29a of the calculation unit 29 performs calculations based on the contour line 51, and sets a rectangle ABCD, which is an approximation of the remaining cross-section 55, as the estimated remaining cross-section 56, as shown in FIG. 7(b). The calculation process for setting this rectangle ABCD will be described later.

[0036] [Target position setting step S112] In the target position setting step S112, for each cross section of the groove W at a predetermined pitch (e.g., 50 mm pitch), the target position of the welding tool 21 within the estimated remaining cross section 56 is set based on the shape of the estimated remaining cross section 56 (the shape of the rectangle ABCD) obtained in the cross section estimation step S110. Specifically, as shown in FIG. 8( a), the target position setting unit 29b of the calculation unit 29 calculates the number of welding layers (the number of welding layers stacked in the depth direction of the groove W) to be included within the estimated remaining cross section 56 and the number of welding passes P to be included in each welding layer, and the welding passes P are allocated within the estimated remaining cross section 56. More specifically, for example, the number of welding layers is determined so that the thickness D1 in the depth direction of each welding layer included in the bottom side CD of the rectangle ABCD is within a predetermined range (e.g., less than 9 mm, less than 4.5 mm, etc.), and each welding layer is allocated with a uniform thickness within the estimated remaining cross section 56. In addition, the number of welding passes P included in each welding layer is determined for each welding layer. For example, the number of stages of welding passes P included in a certain welding layer is determined so that the stage height D3 of the welding passes P included in that welding layer is within a predetermined range (for example, less than 9 mm, less than 4.5 mm, etc.), and each stage of welding passes P is allocated to that welding layer with an equal vertical width. In this way, welding passes P are allocated two-dimensionally within estimated remaining cross section 56, and each target position K is set at a predetermined position on the boundary edge of each welding pass P and stored in memory unit 27.

[0037] [Welding process S114] Subsequently, in welding step S114, a weld bead is formed on remaining cross section 55 by welding tool 21 of welding robot 13, aiming at target position K set in the above-described target position setting step S112. Specifically, as shown in FIG. 8(b), welding tool 21 moves along groove W in the extension direction of groove W (a direction perpendicular to the plane of FIG. 8(b)), performing a welding process to form weld bead H in remaining cross section 55. At this time, the movement of welding tool 21 is controlled so that the tip of welding tool 21 passes through each target position K for each cross section of groove W at a predetermined pitch (for example, 50 mm pitch). Therefore, weld bead H formed on the movement trajectory of the tip of welding tool 21 is formed on welding path P corresponding to target position K. By repeating this welding process, weld beads H are repeatedly formed in remaining cross section 55. This welding process is realized by welding process control unit 33 controlling the operations of welding robot 13 and welding tool 21 based on target position K stored in storage unit 27.

[0038] During the above welding process, welding tool 21 is moved so that groove sensor 23 precedes welding tool 21 in the direction of movement. At this time, welding process control unit 33 acquires information on remaining cross section 55 immediately ahead of moving welding tool 21 from groove sensor 23 in real time. Then, welding process control unit 33 fine-tunes the position of the tip of welding tool 21 in a plane perpendicular to the direction of travel based on the acquired information on remaining cross section 55 immediately ahead. By performing feedback control of the position of welding tool 21 in this manner, the tip of welding tool 21 accurately passes through target position K.

[0039] [Complete S116] When a predetermined number of welding processes have been performed in the above welding step S114, the process ends. At this time, the groove W is filled with multiple weld beads H, and the welding of the column parts 3A and 3B is completed.

[0040] [Resetting the target position S118] Due to an error in the welding process in the above-mentioned welding step S114, the remaining target position K that has been set may become unsuitable for continuing the welding process. Therefore, before the completion (S116), when the welding process in the welding step S114 has progressed for a certain number of layers, the process returns to the sensing step S108. That is, after a certain amount of the welding step S114, a new contour line of the remaining cross section 55 is obtained by the sensing step S108 again, and by going through the cross section estimation step S110 and the target position setting step S112, a new target position K is set based on the new remaining cross section 55, and the welding step S114 is performed. Note that the resetting of the target position S118 may be omitted.

[0041] By repeatedly executing S108 to S118 as described above, finally, the groove W is filled with multiple layers of weld beads H, and welding of the groove W is completed (S116). Then, by completing such welding of the groove W over the entire circumference of the column parts 3A, 3B, welding of the column parts 3A, 3B to each other is completed. After that, the welding robot 13 is detached from the rail 11, and the rail 11 is removed from the column part 3A.

[0042] [Details of the setting of the estimated remaining cross section 56] Next, the calculation process by the cross-section estimation unit 29a for setting the estimated remaining cross-section 56 (quadrant ABCD) in the above-mentioned cross-section estimation step S110 will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a flowchart of this calculation process, and Figs. 10(a) to 10(d) are cross-sectional views of the groove W.

[0043] At the time of the sensing step S108, which is a step preceding this cross-section estimation step S110, a welded portion 91 exists in the groove W, so it is no longer possible to actually measure information about the groove W in an unwelded state. Also, at the time of the initial state (FIG. 5(a)), the rail 11 and the welding robot 13 have not yet been installed, so actual measurement information about the groove W in an unwelded state has not been obtained. Therefore, this calculation processing algorithm sets the rectangle ABCD without using actual measurement information about the groove W in an unwelded state.

[0044] As described above, in the sensing step S108, as shown in Fig. 10(a), the contour line 51 of the cross section near the groove W is acquired. After that, by the calculation processing of the cross section estimation unit 29a of the calculation unit 29, two inflection points located on the groove sensor 23 side are detected from the contour line 51 and defined as point A and point D (S202 in Fig. 9).

[0045] Next, as shown in Fig. 10(b), from the section of the contour line 51 from point A to point D, a linear contour portion starting from point A is extracted as a straight line AL, and this straight line AL is normalized to define a vector AL starting from point A (S204 in Fig. 9). Here, it is confirmed whether or not the inclination angle of the extracted straight line AL is within a predetermined range close to the designed inclination angle of the lower end face 42 (Fig. 5) of the pillar part 3B, and if it is not within the range, extraction may be retried. Furthermore, if the vector AL cannot be defined after the predetermined retries, the vector AL may be defined based on the designed inclination angle of the lower end face 42 (Fig. 5) of the pillar part 3B.

[0046] Next, point B' is defined on an extension of vector AL. Specifically, point B' is defined as a point on the extension of vector AL and whose horizontal distance from point A is the difference between the design depth of the groove W in an unwelded state and the thickness of the welded portion 91 (S206 in FIG. 9). Here, the design depth of the groove W in an unwelded state is known as the wall thickness of the column part 3. The thickness of the welded portion 91 is a known value based on the design thickness (e.g., 5 mm) of the weld bead constituting the welded portion 91 and the number of weld layers formed in the temporary welding step S102. These known numerical information may be input in advance by a user into a computer system constituting the control unit 15 and stored in the memory unit 27.

[0047] Similarly, from the section of the contour line 51 from point A to point D, a linear contour portion starting from point D is extracted as a straight line DL, and this straight line DL is normalized to define a vector DL ​​starting from point D (S208 in FIG. 9). Here, it is confirmed whether the inclination angle of the extracted straight line DL is within a predetermined range close to the designed inclination angle of the upper end surface 41 (FIG. 5) of the column part 3A, and if it is not within the range, extraction may be retried. Furthermore, if the vector DL ​​cannot be defined after the predetermined retry, the vector DL ​​may be defined based on the designed inclination angle of the upper end surface 41 (FIG. 5) of the column part 3A. Next, point C' is defined on the extension of vector DL. Specifically, point C' is defined as a point on the extension of vector DL ​​and whose horizontal distance from point D is the difference between the designed depth of the groove W in the unwelded state and the thickness of the already-welded portion 91 (S210 in FIG. 9).

[0048] Next, as shown in Fig. 10(c), a contour 53 is extracted from the contour 51 in the section between a position slightly below point B' and a position slightly above point C' (S212 in Fig. 9). Then, this contour 53 is approximated to a straight line by the least squares method (this straight line is defined as an approximated line 54). Then, as shown in Fig. 10(d), the intersection of the approximated line 54 and the line AB' is defined as point B, and the intersection of the approximated line 54 and the line DC' is defined as point C (S214 in Fig. 9).

[0049] By the above-mentioned calculation process, the cross section estimation part 29a of the calculation part 29 defines points A, B, C, and D, and sets a quadrangle ABCD with these four points as vertices. As described above, this quadrangle ABCD is an estimated remaining cross section 56 obtained by approximating the remaining cross section 55 to a quadrangle. As shown in FIG. 6(b), point A corresponds to the corner 48 where the surface 44 and the lower end face 42 of the column part 3B intersect, and point D corresponds to the corner 47 where the surface 43 and the upper end face 41 of the column part 3A intersect. Furthermore, point B is set at a position approximately close to the intersection point between the lower end face 42 of the column part 3B and the surface 92 of the already welded portion 91, and point C is set at a position approximately close to the intersection point between the upper end face 41 of the column part 3A and the surface 92 of the already welded portion 91.

[0050] The effects of the welding method and welding device 1 of this embodiment as described above will be described.

[0051] According to the welding method and welding apparatus 1 of this embodiment, in the cross-section estimation step S110, the estimated remaining cross-section 56 is set without using actual measurement information about the cross-section of the groove W in an unwelded state, and the welding process can be performed based on this estimated remaining cross-section 56. That is, the calculation process for setting the estimated remaining cross-section 56 (rectangle ABCD) is as described above, and, for example, actual measurement information about corners 45, 46 (FIG. 5(b)) is not used. Therefore, there is no need to actually measure information about the groove W in an unwelded state.

[0052] In this case, in the unwelded state, there is no need to install a welding robot 13 for measuring information about the groove W or a rail 11 supporting the welding robot 13. If actual measurement information about the groove W in the unwelded state is required, the rail 11 and welding robot 13 are first installed on the column component 3A in the unwelded state, and information about the groove W is acquired by the welding robot 13 and the groove sensor 23. Then, the temporary welding process S102 is performed, and the temporary connection removal process S104 is performed. In the temporary connection removal process S104, the rail 11 and the welding robot 13 may be damaged by the heat generated when the erection piece 4 is thermally cut. Therefore, it is necessary to temporarily remove the rail 11 and the welding robot 13 from the column component 3A before the temporary connection removal process S104. Then, in the robot installation process S106 after the temporary connection removal process S104, the rail 11 and the welding robot 13 are reattached to the column component 3A, which results in double work.

[0053] On the other hand, to avoid such redundant work, it is conceivable to omit the temporary connection portion removal step S104. However, if the temporary connection portion removal step S104 is omitted, it is necessary to perform the welding step S114 in a state in which the temporary connection portion 7 is present. In this case, when welding the groove W near the temporary connection portion 7, a complex operation of the welding robot 13 is required, such as inserting the tip of the welding tool 21 into the groove W while avoiding the erection jig 5, which can be a factor in complicating the operation control.

[0054] In contrast, according to the welding method of this embodiment, as described above, the rail 11 and welding robot 13 do not need to be installed in the unwelded state. Therefore, the temporary welding process S102 and the temporary connection removal process S104 are first performed without the rail 11 and welding robot 13 being installed. Then, in the temporary connection removal process S104, damage to the rail 11 and welding robot 13 due to the heat generated when the erection piece 4 is thermally cut is avoided. Since the rail 11 and welding robot 13 are installed for the first time in the robot installation process S106, the aforementioned double work does not occur. Furthermore, since the welding process S114 is performed after the temporary connection 7 is removed in the temporary connection removal process S104, the welding robot 13 does not need to operate to avoid the temporary connection 7 during the welding process in the welding process S114, and the operation control of the welding robot 13 can be simplified.

[0055] According to the welding method and welding device 1 of this embodiment, as described above, in the cross-section estimation step S110, it is possible to perform the welding process by the welding device 1 even if there is no actually measured information about the cross-section of the unwelded groove W. Therefore, even if the welding step S114 is interrupted for some reason (for example, due to an error in the welding device 1) and the history information is lost, the welding work by the welding device 1 can be resumed from the sensing step S108.

[0056] Furthermore, due to a slight misalignment between the column parts 3, 3 to be welded, a gap may occur between the surface 40 of the backing metal fitting 6 and the inner wall surface of the column parts 3, 3. If such a gap exists, it may be impossible to accurately acquire the cross-sectional shape of the groove W in an unwelded state by the groove sensor 23. In such a case, after the gap is closed by the already welded portion 91 in the temporary welding step S102, welding can be performed even if actual measurement information of the groove W in an unwelded state cannot be obtained.

[0057] 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. [Explanation of symbols]

[0058] 1...welding equipment, 3, 3A, 3B...column parts (objects to be welded), 4...erection piece, 5...construction jig, 7...temporary connection part, 11...rail, 13...welding robot, 15...control part, 21...welding tool (end effector), 23...groove sensor, 29a...cross-section estimation part, 29b...target position setting part, 31...sensing processing control part, 33...welding processing control part, 43, 44...surface, 49...inner surface, 51...contour line, 55...remaining cross section, 56...estimated remaining cross section, 91...already welded part, A, B, C, D...point, AL, DL...vector, H...weld bead, K...target position, W...groove.

Claims

1. A welding method for performing multi-layer welding on a groove of a welding object using a welding robot having a welding end effector and a sensor, A sensing process in which, in a state where a welded portion of a predetermined thickness exists in the groove, the vicinity of the groove is sensed by the sensor of the welding robot, and a contour line of a remaining cross section, which is a cross section of a portion of the groove that remains unwelded, is acquired; a cross section estimation step of estimating the shape of the remaining cross section based on the contour line obtained in the sensing step and calculating an estimated remaining cross section; a target position setting step of setting a target position of the end effector within the estimated remaining cross section based on the estimated remaining cross section obtained in the cross section estimation step; a welding step in which the welding robot forms a weld bead in the remaining cross section by using the end effector while aiming at the target position set in the target position setting step, In the cross section estimation step, The estimated remaining cross section is calculated without using information actually measured about the cross section of the groove in an unwelded state before the already welded portion is formed, The estimated remaining cross section is A quadrilateral ABCD has vertices at points A and D, which correspond to two corners formed by the intersection of the surface of the workpiece and the inner surface of the groove, and points B and C, which are estimated to be points on the two inner surfaces, In the cross section estimation step, two inflection points detected from the contour line obtained in the sensing step are defined as point A and point D, respectively; A vector AL is defined along a linear section of the contour line starting from the point A, A vector DL ​​is defined along a linear section of the contour line starting from the point D, Based on the thickness of the already welded portion and the design depth of the groove in an unwelded state before the already welded portion is formed, point B is defined on an extension line of the vector AL and point C is defined on an extension line of the vector DL. Welding method.

2. The sensing step and the welding step include:

2. The welding method according to claim 1, wherein the welding robot is installed on a rail installed around a steel pipe column that is the object to be welded and is movable on the rail.

3. A temporary welding process in which the steel pipe columns are temporarily connected vertically via temporary connection parts including erection pieces and erection jigs, and the already welded portion is formed in the groove by a welding method that does not use the welding robot; a temporary connection portion removal process in which the temporary connection portion is removed after the temporary welding process; The welding method according to claim 2, further comprising a robot installation process in which the rail is installed around the steel pipe column after the temporary connection removal process and before the sensing process, and the welding robot is installed on the rail.

4. A welding robot having a welding end effector and a sensor, and a control unit that controls the welding robot, the end effector, and the sensor, and performs multi-layer welding on a groove of a welding object. A welding apparatus, The control unit a sensing processing control unit that causes the sensor of the welding robot to sense the vicinity of the groove when a welded portion of a predetermined thickness exists in the groove, and acquires a contour line of a remaining cross section that is a cross section of a portion of the groove that remains unwelded; a cross-section estimation unit that estimates the shape of the remaining cross-section based on the contour line obtained by the sensing processing control unit and calculates an estimated remaining cross-section; a target position setting unit that sets a target position of the end effector within the estimated remaining cross section based on the estimated remaining cross section obtained by the cross section estimation unit; a welding process control unit that causes the welding robot to form a weld bead in the remaining cross section with the end effector, aiming at the target position set by the target position setting unit; The cross section estimation unit The estimated remaining cross section is calculated without using information actually measured about the cross section of the groove in an unwelded state before the welded portion is formed, The estimated remaining cross section is A quadrilateral ABCD has vertices at points A and D, which correspond to two corners formed by the intersection of the surface of the workpiece and the inner surface of the groove, and points B and C, which are estimated to be points on the two inner surfaces, The cross section estimation unit two inflection points detected from the contour line obtained by the sensing processing control unit are defined as the point A and the point D, respectively; A vector AL is defined along a linear section of the contour line starting from the point A, A vector DL ​​is defined along a linear section of the contour line starting from the point D, Based on the thickness of the already welded portion and the design depth of the groove in an unwelded state before the already welded portion is formed, point B is defined on an extension line of the vector AL and point C is defined on an extension line of the vector DL. Welding equipment.

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