JP2024054599A - Welding method and welding equipment - Google Patents

Abstract

[Problem] To provide a welding method and welding device capable of welding a groove in an unwelded state without actual measurement information of the groove. [Solution] The welding method includes a sensing step of acquiring a contour line 51 of a remaining cross section 55 of the groove W that remains unwelded using a groove sensor 23 of a welding robot 13, a cross section estimation step of estimating the shape of the remaining cross section 55 based on the contour line 51 to calculate an estimated remaining cross section 56, a target position setting step of setting a target position K within the estimated remaining cross section 56 based on the estimated remaining cross section 56, and a welding step in which the welding robot 13 forms a weld bead H in the remaining cross section 55 with a welding tool 21 while aiming at the target position K. In the cross section estimation step, the estimated remaining cross section 56 is calculated without using information actually measured about the cross section of the groove W in an unwelded state. [Selected Figure] FIG.

Description

The present invention relates to a welding method and welding equipment.

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. The welding process is then repeatedly performed by 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 by the groove sensor and adjusts the position of the welding tool.

Patent Publication No. 2022-28522

The above welding method is based on the premise that welding is started when the groove is in an unwelded state. However, in this type of welding method, there are situations in which it is desired to start welding when 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 equipment that can perform welding of the groove when there is no actual measurement information for the unwelded groove.

The gist of the present invention is as follows:

[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, comprising: a sensing step in which, when a pre-welded portion of a predetermined thickness exists in the groove, the sensor of the welding robot senses the vicinity of the groove and obtains 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 target position of the end effector is set within the estimated remaining cross-section based on the estimated remaining cross-section obtained in the cross-section estimation step; and a welding step in which the welding robot forms a weld bead in the remaining cross-section with the end effector, 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 pre-welded portion is formed.

[2] The estimated remaining cross section is a quadrangle ABCD with vertices at points A and D, which correspond to two corners formed by the intersection of the surface of the object to be welded and the inner side of the groove, and points B and C, which are estimated as points on the two inner sides, respectively. 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. 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 vector AL and point C is defined on an extension line of vector DL. The welding method described in [1].

[3] The welding method described in [1] or [2], in which the sensing process and the welding process are performed with the welding robot movable on a rail installed around the steel pipe column, which is the object to be welded, installed on the rail.

[4] The welding method according to any one of [1] to [3], further comprising a temporary welding process in which the already welded portion is formed in the groove by a welding method that does not use the welding robot while the steel pipe columns are temporarily connected vertically via a temporary connection part including an erection piece and an erection jig, a temporary connection part 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 and the welding robot is installed on the rail after the temporary connection part removal process and before the sensing process.

[5] A welding device that performs multi-layer welding on a groove of a welding object, comprising a welding robot having an end effector and a sensor, and a control unit that controls the welding robot, the end effector, and the sensor, the control unit having the sensor of the welding robot 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 cross section estimation unit that estimates the shape of the remaining cross section based on the contour line obtained by the sensing process control unit and calculates an estimated remaining cross section, a target position setting unit that sets the 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, and 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 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.

The present invention provides a welding method and welding device that can weld a groove without having actual measurement information on the unwelded groove.

1 is a perspective view showing a welding device according to an embodiment; 2 is a side view of a welding robot provided in the welding device of the present embodiment. FIG. 2 is a block diagram of a control unit provided in the welding device of the present embodiment. FIG. 2 is a flowchart of a welding method according to the present embodiment. 4A and 4B are cross-sectional views of the vicinity of a groove in the welding method of the present embodiment. 4A and 4B are cross-sectional views of the vicinity of a groove in the welding method of the present embodiment. 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. 1A is a cross-sectional view illustrating a target position setting step, and FIG. 1B is a cross-sectional view illustrating a welding step. 13 is a flowchart of a calculation process performed by a cross-section estimation unit for setting an estimated remaining cross-section. 11A to 11D are cross-sectional views illustrating a calculation process performed by a cross-section estimation unit for setting an estimated remaining cross-section.

Below, an embodiment of the welding method and welding device of the present invention will be described with reference to the drawings. In the following description, identical elements or elements having the same functions will be given the same reference numerals, and duplicate descriptions may be omitted.

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, rectangular steel pipes, and a number of column components 3 are stacked vertically and welded together to construct a rectangular steel pipe column. The column components 3, 3 to be welded are arranged so that their material axes are aligned and the horizontal ends of the column components 3, 3 are close to and face each other around the entire circumference. A groove W is formed where these ends face each other, and the groove W extends in a horizontal plane around the entire circumference of the column component 3.

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

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.

(rail)
The rail 11 forms 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 lower column part 3 via a predetermined fixture 11a and is disposed 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.

(welding robot)
2 is a side view of the welding robot 13. The welding robot 13 is a six-axis vertical articulated robot, and the arm 13a of the welding robot 13 includes a base L0 (pedestal) fixed to the mounting seat 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 leading edge link L6 rotatable about a sixth axis J6 relative to the fifth link L5. The above-mentioned axes J1, J4, and J6 are parallel to the paper surface of FIG. 2, and the axes J2, J3, and J5 are perpendicular to the paper surface of FIG. 2. The welding robot 13 is provided with a driving source (not shown) such as a motor for rotating each of the links L 1 to L 6 , and the driving source operates according to a control signal from the control unit 15 .

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 welding robot 13 attached to this 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 becomes easy to match the movement range of the end effector to a suitable range of movement within the range of movement of the welding robot 13. In other words, it becomes easy to avoid a state in which the welding robot 13 operates near the movement limit of the arm 13a, for example.

A welding tool 21 serving as a welding end effector is mounted on the tip (leading edge 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 on 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 specified mounting jig so as to protrude to the side of the welding tool 21.

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

Figure 3 is a block diagram showing the functional configuration of the control unit 15. As shown in Figure 3, the control unit 15 has, as its functional configuration (hereinafter referred to as "functional modules"), a memory unit 27 that stores information, a calculation unit 29 that performs each calculation, a sensing process control unit 31 that performs sensing processing, and a welding process control unit 33 that performs welding processing. The calculation unit 29 has a cross-section estimation unit 29a and a target position setting unit 29b.

These functional modules are merely a division of 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 electrical circuit (e.g., a logic circuit) or an integrated circuit (ASIC: Application Specific Integrated Circuit) that integrates these.

The sensing process control unit 31 controls the operation of the welding robot 13 and the groove sensor 23, and performs sensing processing to acquire information about the groove W (hereinafter "groove information") by having the welding robot 13 and the groove sensor 23 cooperate with each other. 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 at each cross section at a predetermined pitch (e.g., 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.

The operation of the welding robot 13 controlled by the sensing process control unit 31 includes the movement of the welding robot 13 on the rail 11 (travel of the carriage 17) and the driving of the arm 13a of the welding robot 13, but it is preferable that the above sensing process is performed in a state where the movement of the welding robot 13 on the rail 11 is stopped. In this case, the groove sensor 23 is moved only by the movement of the arm 13a of the welding robot 13, so the positional accuracy of the groove sensor 23 during scanning is high, and as a result, the accuracy of the acquired groove information is also high.

The welding process control unit 33 controls the operation of the welding robot 13 and the welding tool 21, and executes a welding process in which the welding robot 13 and the welding tool 21 cooperate to weld within the groove W. Specifically, the welding process control unit 33 moves the welding tool 21 along the groove W in the extension direction of the groove W by the operation of the welding robot 13, while the welding tool 21 forms a weld bead within the groove W. At this time, the welding process control unit 33 controls the ON/OFF of the welding tool 21 and the welding state by the welding tool 21 (e.g., the welding current value and the supply speed of the filler metal).

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

(Welding method)
Next, the 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 Figures 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 called the "column part 3A", and the column part 3 connected above it will be called 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 Figure 4, it includes a temporary welding process S102, a temporary connection part 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.

〔initial state〕
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 construction 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 in the vertical direction 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 block the gap between them. The groove W formed between the column part 3A and the column part 3B in this way forms a trapezoidal cross-sectional groove extending horizontally to the same depth as 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 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.

[Pre-welding step S102]
From the above initial state, as shown in FIG. 5B, temporary 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 part 3A and the surface 40 of the backing metal 6, and the corner 46 between the lower end surface 42 of the column part 3B and the surface 40 of the backing metal 6, and the column part 3A and the column part 3B are temporarily welded. Here, the rail 11 and the welding robot 13 have not yet been installed, so naturally, this temporary welding process is performed by a welding method that does not use the welding robot 13. For example, in this embodiment, the temporary welding process is performed by manual welding by a worker. As a result, a welded portion 91 having a thickness of about two layers of weld beads is formed at the bottom of the groove W.

[Temporary connection portion removal step S104]
After the above-mentioned temporary welding process S102, the temporary connection part 7 is removed. Specifically, the construction 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 by the already welded part 91.

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

[Sensing step S108]
After this sensing step S108, each step is performed using the welding device 1 that has become available. In the sensing step S108, as shown in FIG. 6B, 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 in each cross section. Here, a contour line 51 of the cross section near the groove W is acquired for each cross section of a predetermined pitch (for example, 50 mm pitch) of the groove W. The contour line 51 includes a contour of a part of the surface 44 of the column part 3B, a contour of the lower end surface 42 of the column part 3B, a contour of the surface 92 of the already welded portion 91, a contour of the upper end surface 41 of the column part 3A, and a contour of a part of the surface 43 of the column part 3A.

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

[Cross-section estimation step S110]
In the cross-section estimation step S110, for each cross-section of the groove W at a predetermined pitch (for example, 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 means a cross-section of the groove W that remains at the present time, as shown in FIG. 7(a), in other words, a cross-section of a portion of the groove W that remains unwelded. For example, here, the remaining cross-section 55 is a cross-section obtained by removing the cross-section of the already welded portion 91 (see FIG. 5(b)) from the cross-section of the groove W (see FIG. 5(a)) in an unwelded state. In this cross-section estimation step S110, the cross-section estimation unit 29a of the calculation unit 29 performs calculation based on the above-mentioned contour line 51, and sets a rectangle ABCD that approximates the remaining cross-section 55 to a rectangle 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.

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

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

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

[Complete S116]
When a predetermined number of welding processes have been performed by the above-mentioned 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.

[Resetting the target position S118]
Due to an error in the welding process in the above welding step S114, the remaining target position K that has already 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 to a certain number of layers, the process returns to the sensing step S108. That is, the contour line of a new remaining cross section 55 after a certain amount of the welding step S114 is obtained by the sensing step S108 again, and the cross section estimation step S110 and the target position setting step S112 are performed, so that the target position K based on the new remaining cross section 55 is set again, and the welding step S114 is performed. Note that the resetting of the target position S118 may be omitted.

By repeatedly executing steps S108 to S118 as described above, the groove W is finally 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 around the entire circumference of the column parts 3A and 3B, welding of the column parts 3A and 3B to each other is completed. After that, the welding robot 13 is removed from the rail 11, and the rail 11 is removed from the column part 3A.

[Details of setting 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 (rectangle ABCD) in the above-mentioned cross-section estimation step S110 will be described with reference to Figures 9 and 10. Figure 9 is a flowchart of this calculation process, and Figures 10(a) to 10(d) are cross-sectional views of the groove W.

At the time of the sensing process S108, which is the process preceding this cross-section estimation process S110, a welded portion 91 exists in the groove W, so information on the groove W in an unwelded state can no longer be measured. Also, at the time of the initial state (Figure 5 (a)), the rail 11 and welding robot 13 have not yet been installed, so no actual measurement information on the groove W in an unwelded state has been obtained. Therefore, this calculation processing algorithm sets the rectangle ABCD without using actual measurement information on the groove W in an unwelded state.

As described above, the sensing step S108 obtains the contour line 51 of the cross section near the groove W as shown in FIG. 10(a). Then, the cross section estimation unit 29a of the calculation unit 29 performs calculation processing to detect two inflection points located on the groove sensor 23 side from the contour line 51, and these are defined as points A and D (S202 in FIG. 9).

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 the inclination angle of the extracted straight line AL is within a predetermined range close to the designed inclination angle of the lower end surface 42 of the pillar part 3B (FIG. 5), and if it is not within that range, the extraction may be retried. Furthermore, if the vector AL cannot be defined after the predetermined retry, the vector AL may be defined based on the designed inclination angle of the lower end surface 42 of the pillar part 3B (FIG. 5).

Next, point B' is defined on the extension of vector AL. Specifically, a point on the extension of vector AL and a horizontal distance from point A that is the difference between the design depth of the unwelded groove W and the thickness of the welded portion 91 is defined as point B' (S206 in FIG. 9). Here, the design depth of the unwelded groove W 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 process S102. These known numerical information may be input in advance by a user into the computer system constituting the control unit 15 and stored in the memory unit 27.

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, the extraction may be retried. In addition, when the vector DL cannot be defined by 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, a point C' is defined on the extension line of the vector DL. Specifically, a point on the extension line of the 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 is defined as point C' (S210 in FIG. 9).

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

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

The effects of the welding method and welding device 1 of this embodiment as described above will now be explained.

According to the welding method and welding device 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 of corners 45, 46 (Figure 5 (b)) is not used. Therefore, there is no need to actually measure information about the groove W in an unwelded state.

In this case, in the unwelded state, there is no need to install a welding robot 13 for measuring information on the groove W or a rail 11 supporting the welding robot 13. If actual measurement information on the groove W in the unwelded state is required, the rail 11 and the welding robot 13 are first installed on the column part 3A in the unwelded state, and the welding robot 13 and the groove sensor 23 acquire information on the groove W. Then, the temporary welding process S102 is performed and the temporary connection removal process S104 is performed. Here, in the temporary connection removal process S104, the rail 11 and the welding robot 13 may be damaged due to the influence of heat generated when the erection piece 4 is thermally cut, so it is necessary to remove the rail 11 and the welding robot 13 from the column part 3A once 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 attached to the column part 3A again, which is a double effort.

On the other hand, in order to avoid such double work, it is also possible to omit the temporary connection removal step S104. However, if the temporary connection removal step S104 is omitted, it is necessary to perform the welding step S114 with the temporary connection 7 present. In this case, when welding the groove W near the temporary connection 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 construction jig 5, which can cause the operation control to become complicated.

In contrast, according to the welding method of this embodiment, as described above, the rail 11 and the welding robot 13 do not need to be installed when the rail 11 and the welding robot 13 are not yet installed. Therefore, the temporary welding process S102 and the temporary connection removal process S104 are first performed in a state in which the rail 11 and the welding robot 13 are not installed. Then, in the temporary connection removal process S104, damage to the rail 11 and the welding robot 13 due to the heat generated when the erection piece 4 is thermally cut is avoided. After that, the rail 11 and the welding robot 13 are installed for the first time in the robot installation process S106, so there is no need to do the double work as described above. In addition, 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 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.

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 using the welding device 1 even if there is no actual measurement information about the cross-section of the groove W in an unwelded state. 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 using the welding device 1 can be resumed from the sensing step S108.

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

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. It is also possible to construct modified versions by utilizing the technical matters described in the above-described embodiment. The configurations of each embodiment may be used in appropriate combination.

1...welding device, 3, 3A, 3B...column parts (welding objects), 4...erection piece, 5...construction jig, 7...temporary connection, 11...rail, 13...welding robot, 15...control unit, 21...welding tool (end effector), 23...groove sensor, 29a...cross-section estimation unit, 29b...target position setting unit, 31...sensing process control unit, 33...welding process control unit, 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 (5)

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 in which 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 obtained;
a cross section estimation step of estimating a 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;
Welding method. The estimated remaining cross section is
A quadrilateral ABCD having vertices at points A and D corresponding to two corners formed by the intersection of the surface of the welding object and the inner surface of the groove, and points B and C estimated as 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 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, the point B is defined on an extension line of the vector AL and the point C is defined on an extension line of the vector DL.
The welding method according to claim 1. The sensing step and the welding step include:
3. The welding method according to claim 1, wherein the welding robot is disposed on a rail installed around a steel pipe column that is the object to be welded and is movable on the rail. A temporary welding process in which the already welded portion is formed in the groove by a welding method that does not use the welding robot in a state in which the steel pipe columns are temporarily connected vertically via temporary connection parts including an erection piece and an erection jig;
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 3, further comprising a robot installation process in which the rail is installed around the steel pipe column and the welding robot is installed on the rail after the temporary connection removal process and before the sensing process. 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.
The control unit is
a sensing processing control unit that causes the sensor of the welding robot to sense the vicinity of the groove in a state in which 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 cross section estimation unit that estimates a shape of the remaining cross section based on the contour line obtained by the sensing process 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 by using the end effector while aiming at the target position set by the target position setting unit,
The cross section estimation unit
Calculating an estimated remaining cross section without using information actually measured about the cross section of the groove in an unwelded state before the already-welded portion is formed.
Welding equipment.

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