Welding method

Abstract

This invention provides a welding method that allows the robot arm to move in an approaching manner so that the welding tool of the robot arm can reach the abutting portion at the midpoint in the depth direction of the two adjacent sides of the front of one side of the steel column, even for large steel columns, while avoiding a decrease in work efficiency due to frequent approaching movements. [Solution] This welding method uses a support structure 1 to support the robot arm 2. The robot arm 2 is used to weld the butt joint portion 31 between the lower square steel column 3A and the upper square steel column 3B. In the basic position, welding is not performed in areas that the robot arm 2 cannot reach (specific welding locations F), and welding is performed by the robot arm 2 in the weldable area G (thick dotted line area) for a number of passes less than the required number. Then, after removing the erection piece 32, welding is performed on the entire structure.

Description

Technical Field

[0001] This invention relates to a welding method for welding the butting portion of an upper steel column and a lower steel column with a robot arm.

Background Art

[0002] Conventionally, there has been known a welding method in which an upper steel column and a lower steel column are butted together, the upper steel column is temporarily fixed to the lower steel column by an erection piece, and the butting portion of the upper steel column and the lower steel column is welded using a welding tool attached to a robot arm.

[0003] Patent Document 1 discloses a mounting jig for mounting a robot arm used for welding the butting portion of columns composed of steel columns arranged vertically on the columns. This mounting jig includes a pair of first support members that support the robot arm, and a rail member that is supported by the pair of first support members and guides the travel of a carriage on which the robot arm is placed. The pair of first support members extend in a horizontal first direction and are detachably fixed to the outer surface of the column so as to sandwich the column, and the rail member is fixed across the pair of first support members so as to extend in a horizontal second direction intersecting the first direction.

[0004] With such a support structure, the pair of first support members extend in the first direction and are fixed to the column so as to sandwich the column, and the rail member is fixed to the pair of first support members so as to extend in the second direction. Therefore, the mounting jig can be fixed to the column regardless of the size (diameter) of the column.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, for large-sized square steel columns, there was a drawback in that the welding tool of the robot arm could not reach the abutting portion located midway in the depth direction of the two adjacent sides of the front of the column.

[0007] In view of the above circumstances, this invention aims to provide a welding method that allows the robot arm to move in an approaching manner so that the welding tool of the robot arm can reach the abutting portion at the midpoint in the depth direction of the two adjacent sides on one front side of the steel column, even for large steel columns, while avoiding a decrease in work efficiency due to frequent approaching movements. [Means for solving the problem]

[0008] The welding method of this invention, in order to solve the above problems, involves butting together an upper steel column and a lower steel column, temporarily fixing the upper and lower steel columns with erection pieces of the upper and lower steel columns, and welding the butt joint portion of the upper and lower steel columns using a welding tool attached to a robot arm. The robot arm described above is supported by a support structure attached to the lower steel column described above. The above-described support structure comprises a pair of support members extending in a first direction within a horizontal plane perpendicular to the lower steel column, sandwiching the lower steel column in that plane, and an operating mechanism attached to the support members in another horizontal plane perpendicular to the lower steel column, which guides the robot arm to travel in a second direction intersecting the first direction and can also change its position toward the first direction. The process involves the robot arm, at a basic position a predetermined distance away from the lower steel column in the first direction, performing welding in a number of passes less than the required number of passes within the area where welding is possible, without welding in areas that the robot arm cannot reach. After performing welding a number of times less than the required number of passes, the process involves removing the erection piece from specific welding locations and other locations that the robot arm cannot reach. After removing the erection piece, the robot arm is moved to a position closer to the lower steel column than the basic position, and to a position where the welding tool can reach the specific welding location. Before moving the robot arm to the approach position, the welder performs additional welding on the specific welding location for a number of passes equal to or less than the required number of passes, or, after moving the robot arm to the approach position, the robot arm or the welder performs additional welding on the specific welding location for a number of passes equal to or less than the required number of passes, The process involves using the robot arm, which has been moved to the aforementioned proximity position, to perform welding on all welding points, including the specific welding point, for the remaining number of passes relative to the required number of passes. It is characterized by including.

[0009] With the welding method described above, welding is not performed in areas that the robot arm cannot reach from the basic position. Instead, welding is performed in the areas that can be welded using the welding tool on the robot arm, for a number of passes less than the required number. Then, for the specific welding location, welding is performed for the same number of passes as the number of passes missing from the required number. After removing the erection piece, the robot arm is moved to the approach position to perform welding on all welding locations, including the specific welding location, for the remaining number of passes relative to the required number. In other words, by moving the robot arm from the basic position to the approach position once, the required number of passes can be performed on all welding locations, thus avoiding a decrease in work efficiency due to frequent movement of the robot arm.

[0010] In the welding method described above, the welding operator may perform the separate welding described above before removing the erection piece.

[0011] Alternatively, in the welding method described above, the welding operator may perform the separate welding after removing the erection piece and before moving the robot arm to the approach position.

[0012] Alternatively, in the welding method described above, the welding operator may perform the separate welding after removing the erection piece and moving the robot arm to the approach position.

[0013] Furthermore, the welding method of this invention involves butting an upper steel column and a lower steel column together, temporarily fixing the upper and lower steel columns together with erection pieces of the upper and lower steel columns, and welding the butt joint portion of the upper and lower steel columns using a welding tool attached to a robot arm. The robot arm described above is supported by a support structure attached to the lower steel column described above. The above-described support structure comprises a pair of support members extending in a first direction within a horizontal plane perpendicular to the lower steel column, sandwiching the lower steel column in that plane, and an operating mechanism attached to the support members in another horizontal plane perpendicular to the lower steel column, which guides the robot arm to travel in a second direction intersecting the first direction and can also change its position toward the first direction. The process involves the robot arm performing welding a required number of passes within the area where welding is possible, while not welding areas that the robot arm cannot reach, at a basic position a predetermined distance away from the lower steel column in the first direction. After performing the required number of welding passes as described above, the process involves removing the erection pieces from specific welding locations and other locations that the robot arm cannot reach. After removing the erection piece, the robot arm is moved to a position closer to the lower steel column than the basic position, and to a position where the welding tool can reach the specific welding location. After moving the robot arm to the aforementioned proximity position, the robot arm performs the required number of additional welds on the specific welding location. It is characterized by including.

[0014] In these welding methods, the movement of the operating mechanism in the first direction may be manually performed, and after the movement, the position of the operating mechanism may be fixed by bolt fastening or pin insertion.

[0015] In these welding methods, the operating mechanism may include a slide member for moving in the first direction.

Effect of the Invention

[0016] According to the present invention, even for a steel column of a large size, while supporting the robot arm so that the welding tool of the robot arm can reach the butting portion at the intermediate position in the depth direction of the side surfaces adjacent to both sides of the front surface of one side of the steel column, it is possible to avoid a decrease in work efficiency due to frequently performing this approaching movement.

Brief Description of the Drawings

[0017] [Figure 1] It is a front view showing a schematic configuration of a support structure of a robot arm used in a welding method according to an embodiment. [Figure 2] It is a plan view of the support structure shown in FIGURE 1. [Figure 3] It is a cross-sectional view showing a schematic of a support member and a rail member constituting the support structure shown in FIGURE 1. [Figure 4] It is an explanatory view showing a welding teaching position of the support structure shown in FIGURE 1, where FIGURE (a) shows odd passes and FIGURE (b) shows even passes. [Figure 5] It is an explanatory view showing a process of welding a range that can be welded by a robot arm in the basic position of the support structure shown in FIGURE 1. [Figure 6] It is an explanatory view showing a state where the erection piece is removed after the process shown in FIGURE 5 and the robot arm is moved to the approaching position. [Figure 7] It is an explanatory view showing a process of welding a specific welding portion after the process shown in FIGURE 6. [Figure 8]This is an explanatory diagram showing the process of welding the required number of passes to the entire butt joint between the lower and upper square steel columns after the process shown in Figure 7. [Modes for carrying out the invention]

[0018] The embodiments of this invention will now be described based on the attached drawings. As shown in Figures 1 and 2, the welding method of the embodiment uses a support structure 1 that movably supports the robot arm 2. The robot arm 2 is used for welding the butt joint portion 31 between the lower square steel column 3A and the upper square steel column 3B that constitute the square steel column 3. Note that the steel pipe to be welded is not limited to a square steel pipe.

[0019] The lower square steel column 3A and the upper square steel column 3B are each composed of four flat sections and four curved sections located between these flat sections. Erection pieces 32 are welded to each of the aforementioned flat sections of the lower square steel column 3A and the upper square steel column 3B. In the initial stages of welding the butt joint 31 between the lower square steel column 3A and the upper square steel column 3B, the two erection pieces 32 on the upper and lower sides of the lower square steel column 3A and the upper square steel column 3B are temporarily fixed together by the existing temporary fasteners 4.

[0020] In this embodiment, the support structure 1 is assembled to the lower square steel column 3A such that a pair of support members 11, 11 and two operating mechanisms 12, 12 that guide the movement of each robot arm 2 form a grid shape.

[0021] Each support member 11 is made of, for example, an H-shaped steel and is fixed to the two opposing planar sections of the lower corner steel column 3A by L-angles 5 attached to the two opposing planar sections of the lower corner steel column 3A. That is, the pair of support members 11, 11 are attached to the lower corner steel column 3A in a horizontal plane perpendicular to the lower corner steel column 3A, and extend in a first direction (X direction: parallel to the two opposing planar sections) within the horizontal plane.

[0022] The operating mechanism 12 is positioned at one end and the other end of the pair of support members 11, 11. Each operating mechanism 12 is supported by the support members 11, 11 in another horizontal plane perpendicular to the lower square steel column 3A, and can guide each robot arm 2 to travel in a second direction (Y direction) perpendicular to the first direction, as well as change its position toward the first direction.

[0023] The operating mechanism 12 comprises a rail member 121 and a rail horizontal movement section 125. The rail horizontal movement section 125 moves the rail member 121 horizontally in the first direction. For example, the rail horizontal movement section 125 comprises a straight rail section 1251 arranged on each support member 11 and a slide member 1252 that moves horizontally in the first direction on this straight rail section 1251. The upper surface of this slide member 1252 and the rail frame 121a, which is the lower surface portion of the rail member 121, are fixed to each other by a fastening member 1252a.

[0024] Each rail member 121 guides each robot arm 2 in the second direction, and existing rail members can be used. For example, as shown in Figure 3, the rail member 121 comprises a rail frame 121a placed on a support member 11 and a rail body 121b fixed to the rail frame 121a. A carriage 22 on which the robot arm 2 is placed is attached to the rail body 121b, and the robot arm 2 is guided to travel in the second direction (Y direction) by the self-propelled movement of this carriage 22.

[0025] In the above-described operating mechanism 12, when the rail member 121 is moved linearly by human power, the two sliding members 1252 that support the left and right ends of each rail member 121 move in the same direction in the first direction (X direction) from the basic position shown in the figure (where the robot arm 2 is a predetermined distance away from the lower square steel column 3A in the first direction) in the rail horizontal movement section 125. This allows the robot arm 2 to move not only in the second direction (Y direction) corresponding to the width direction of the square steel column 3, but also in the first direction (X direction) corresponding to the direction of approaching / moving away from the square steel column 3, so that the rail member 121 can be positioned in the approach position shown in the figure (a position where the welding tool (welding torch, etc.) can reach the specific welding location F described later). As a result, even for larger square steel columns 3, the tip of the robot arm 2 (the tip of the welding tool) can reach not only the front side of the square steel column 3 but also the middle part of the side side of the square steel column 3 (specific welding location F), enabling accurate robot welding.

[0026] Figure 4 illustrates the teaching points T1 to T17 for welding on the robot arm 2. For odd-numbered passes, the teaching points are in the order T1 to T17, as shown in (a) of the figure, and for even-numbered passes, the teaching points are in the order T17 to T1, as shown in (b) of the figure. A pass refers to one welding operation performed along the weld line. As a basic operation, for odd-numbered passes, one robot arm 2 welds teaching points T1 to T9, stops welding, changes the posture of the robot arm 2, and welds teaching points T9 to T17. For odd-numbered passes, teaching points T1 to T9 are the first half of the pass, and teaching points T9 to T17 are the second half of the pass. Also, for even-numbered passes, one robot arm 2 welds teaching points T17 to T9, stops welding, changes the posture of the robot arm 2, and welds teaching points T9 to T1. For even-numbered paths, teaching points T9-T17 represent the first half of the path, and teaching points T1-T9 represent the second half. Teaching points T1-T4, T6-T12, and T14-T17 represent straight sections, while teaching points T4-T6 and T12-T14 represent curved sections. Note that odd-numbered and even-numbered paths may be in the same direction.

[0027] In this embodiment of the welding method, the robot arm 2, from the lower square steel column 3A, at the basic position described above, does not weld areas that the robot arm 2 cannot reach (specific welding areas F), as shown in Figure 5, but performs welding in a number of passes less than the required number in the weldable range G (areas indicated by thick dotted lines). The specific welding areas F that the robot arm 2 cannot reach are, for example, located at teaching points T1 to T2 and teaching points T16 to T17 in Figure 4, and the weldable range G is the range of teaching points T2 to T9 and teaching points T9 to T16.

[0028] The number of welds that falls short of the required number of passes refers to a number of welds that is fewer than the number of passes required for a complete weld, and is judged to be such that even if the erection piece 32 is removed by cutting or the like, no structural problems such as the upper corner steel column 3B falling off the lower corner steel column 3A will occur. For example, this would be 3 to 6 passes in total, including both odd and even passes.

[0029] After performing welding a number of times less than the required number of passes, as shown in Figure 6, a total of four pairs of erection pieces 32 are removed from specific welding locations F that the robot arm 2 cannot reach, and from other locations (the side that interferes with the rail member 121).

[0030] Next, the robot arm 2 is moved to the aforementioned proximity position. Then, as shown in Figure 7, the robot arm 2, now in this proximity position, performs additional welding on the specific welding location F for the same number of passes as the required number of passes.

[0031] Next, as shown in Figure 8, the robot arm 2, which has been moved to the aforementioned close-up position, performs welding on all welding points, including the specific welding point F, using the remaining number of passes relative to the required number of passes. The required number of passes varies depending on the size of the steel pipe column, but may be, for example, 21 passes, 28 passes, etc.

[0032] With the welding method described above, welding is not performed on areas that the robot arm 2 cannot reach from the basic position. Instead, welding is performed using the welding tool on the robot arm 2 for a number of passes less than the required number of passes within the reachable range. Then, for the specific welding point F, welding is performed for the same number of passes as the number of passes less than the required number of passes. After removing the erection piece 32, the robot arm 2 is moved to the approach position to perform welding on all welding points, including the specific welding point F, for the remaining number of passes relative to the required number of passes. In other words, by moving the robot arm 2 from the basic position to the approach position once, the required number of passes of welding can be performed on all welding points, thus avoiding a decrease in work efficiency due to frequent movement of the robot arm 2 to the approach position.

[0033] In the welding method described above, the robot arm 2, moved to the aforementioned proximity position, performed additional welding on the specific welding location F for a number of passes equal to or less than the required number of passes, but this is not limited to this. The welder may perform the additional welding after removing the erection piece 32 from the specific welding location F and before moving the robot arm 2 to the aforementioned proximity position. Alternatively, the welder may perform the additional welding after removing the erection piece 32 from the specific welding location F and after moving the robot arm 2 to the aforementioned proximity position.

[0034] Furthermore, the welder may perform the above-mentioned separate welding before removing the erection piece 32 at the specific welding location F.

[0035] Furthermore, the operating mechanism 12 may not include a rail horizontal movement section 125. The movement of the rail member 121 on the support member 11 may be performed manually by sliding the rail member 121 on the support member 11, and after movement, the rail member 121 may be fixed to the support member 11 by fastening bolts or inserting pins.

[0036] In the example above, welds were performed with fewer than the required number of passes in addition to the specific welding point F, the erection piece 32 was cut, the robot arm 2 was moved, welds were performed with fewer than the required number of passes at the specific welding point F, and then the remaining passes were welded over the entire piece. However, the method is not limited to this, and the following welding methods may also be used.

[0037] In other words, this welding method involves, for example, butting together an upper square steel column 3B and a lower square steel column 3A, temporarily fixing the upper square steel column 3B and the lower square steel column 3A together with the erection pieces 32 of the upper square steel column 3B and the lower square steel column 3A, and welding the butt joint portion of the upper square steel column 3B and the lower square steel column 3A using a welding tool attached to the robot arm 2. The robot arm 2 is supported by a support structure 1 attached to the lower square steel column 3A. The support structure 1 comprises a pair of support members 11 extending in a first direction within a horizontal plane perpendicular to the lower corner steel column 3A, sandwiching the lower corner steel column 3A, and an operating mechanism 12 attached to the support members 11 in another horizontal plane perpendicular to the lower corner steel column 3A, which guides the robot arm 2 to travel in a second direction intersecting the first direction and can also change its position toward the first direction. The robot arm 2, at a basic position a predetermined distance away from the lower corner steel column 3A in the first direction, performs welding in the required number of passes within the area where welding is possible, without welding in areas that the robot arm 2 cannot reach. After performing the required number of welding passes as described above, the process involves removing the specific welding location F and other locations where the robot arm 2 cannot reach. After removing the erection piece 32, the robot arm 2 is moved to a position closer to the lower corner steel column 3A than the basic position, and to a position where the welding tool can reach the specific welding location F. After moving the robot arm 2 to the above-mentioned approach position, the robot arm 2 performs the required number of additional welds on the specified welding location F, It may include.

[0038] Although embodiments of this invention have been described above with reference to the drawings, this invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as this invention, or within the equivalent scope. [Explanation of symbols]

[0039] 1:Support structure 2: Robot arm 3: Square steel column 3A: Lower square steel column 3B: Upper corner steel column 4: Temporary fasteners 5: L-angle 11: Support member 12: Operating mechanism 22: Carriage 31: Butt joint 32: Erection Piece 121: Rail component 121a: Rail mount 121b: Rail body 125: Rail horizontal movement section 1251: Straight rail section 1252: Sliding member 1252a: Fastening member F: Specific welding locations G: Weldable range

Claims

1. A welding method comprising butting together an upper steel column and a lower steel column, temporarily fixing the upper and lower steel columns with erection pieces of the upper and lower steel columns, and welding the butt joint between the upper and lower steel columns using a welding tool attached to a robot arm, The robot arm described above is supported by a support structure attached to the lower steel column described above. The above-described support structure comprises a pair of support members extending in a first direction within a horizontal plane perpendicular to the lower steel column, sandwiching the lower steel column in that plane, and an operating mechanism attached to the support members in another horizontal plane perpendicular to the lower steel column, which guides the robot arm to travel in a second direction intersecting the first direction and can also change its position toward the first direction. The process involves the robot arm, at a basic position a predetermined distance away from the lower steel column in the first direction, performing welding in a number of passes less than the required number of passes within the range where welding is possible, without welding in areas that the robot arm cannot reach. After performing welding a number of times less than the required number of passes, the process involves removing the erection piece from specific welding locations and other locations that the robot arm cannot reach. After removing the erection piece, the robot arm is moved to a position closer to the lower steel column than the basic position, and to a position where the welding tool can reach the specific welding location. Before moving the robot arm to the approach position, the welder performs additional welding on the specific welding location for a number of passes equal to or less than the required number of passes, or, after moving the robot arm to the approach position, the robot arm or the welder performs additional welding on the specific welding location for a number of passes equal to or less than the required number of passes, The process involves using the robot arm, which has been moved to the aforementioned proximity position, to perform welding on all welding points, including the specific welding point, for the remaining number of passes relative to the required number of passes. A welding method characterized by including the following.

2. A welding method according to claim 1, characterized in that the welding operator performs the separate welding before removing the erection piece.

3. A welding method according to claim 1, characterized in that after removing the erection piece and before moving the robot arm to the approach position, the welding operator performs the separate welding.

4. A welding method according to claim 1, characterized in that the welding operator performs the separate welding after the erection piece has been removed and the robot arm has been moved to the approach position.

5. A welding method comprising butting together an upper steel column and a lower steel column, temporarily fixing the upper and lower steel columns with erection pieces of the upper and lower steel columns, and welding the butt joint between the upper and lower steel columns using a welding tool attached to a robot arm, The robot arm described above is supported by a support structure attached to the lower steel column described above. The above-described support structure comprises a pair of support members extending in a first direction within a horizontal plane perpendicular to the lower steel column, sandwiching the lower steel column in that plane, and an operating mechanism attached to the support members in another horizontal plane perpendicular to the lower steel column, which guides the robot arm to travel in a second direction intersecting the first direction and can also change its position toward the first direction. The process involves the robot arm, at a basic position a predetermined distance away from the lower steel column in the first direction, performing welding in the required number of passes within the area where welding is possible, without welding in areas that the robot arm cannot reach. After performing the required number of welding passes as described above, the process involves removing the erection pieces from specific welding locations and other locations that the robot arm cannot reach. After removing the erection piece, the robot arm is moved to a position closer to the lower steel column than the basic position, and to a position where the welding tool can reach the specific welding location. After moving the robot arm to the aforementioned proximity position, the robot arm performs the required number of additional welds on the specific welding location. A welding method characterized by including the following.

6. A welding method according to claim 1 or claim 5, characterized in that the movement of the operating mechanism toward the first direction is performed manually, and the position of the operating mechanism is fixed after the movement by fastening a bolt or inserting a pin.

7. A welding method according to claim 1 or claim 5, wherein the operating mechanism comprises a sliding member for movement in the first direction.

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