Welding system

Abstract

To provide a welding system which can perform welding having stable quality, even when a welding part of a multi-layer fill is formed.SOLUTION: In a control device 70 of a welding system 100, among welding beads constituting each welding bead layers B1 to B3, a first angle θ1 to a horizontal direction of a torch tip when lower layer beads B11 and B31 contacting a horizontal surface 14 are formed is set to be larger than a second angle θ2 to the horizontal direction of the torch tip when upper layer beads B12, B23 and B34 contacting an inclined surface 15 are formed, and a third angle θ3 to the horizontal direction when intermediate beads B22, B32 and B33 between the lower layer beads B11, B21 and B31 and the upper layer beads B12, B23 and B34 are formed is set to be an intermediate angle between the first angle θ1 and the second angle θ2.SELECTED DRAWING: Figure 4E

Description

Technical Field

[0001] The present invention relates to a welding system including a welding robot for welding an upper member and a lower member.

Background Art

[0002] As this type of technology, for example, in Patent Document 1, at the groove of an upper steel pipe column and a lower steel pipe column that are temporarily fixed by connecting the erection pieces with a jig, while supplying molten welding material from the tip of a torch attached to a welding robot, a welding method for a steel pipe column that welds the upper steel pipe column and the lower steel pipe column has been proposed. In this welding method, an articulated robot is used as the welding robot, the articulated robot body is mounted on a carriage, and while the carriage is running along a rail member, the articulated robot is operated to perform welding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the welding system shown in Patent Document 1, in order to form a weld bead layer composed of a plurality of weld beads so as to be stacked in the vertical direction, a multi-layered weld portion may be formed by sequentially repeating from the end side in the depth direction of the groove to the opening edge of the groove. However, when performing such welding, depending on the orientation of the tip of the torch to which the welding material is supplied, there is a risk that stable-quality welding cannot be performed.

[0005] The present invention has been made in view of such points, and an object thereof is to provide a welding system capable of performing stable-quality welding even when a multi-layered weld portion is formed.

Means for Solving the Problems

[0006] In view of the above problems, a welding system according to the present invention is a welding system including a welding robot that performs welding of an upper member and a lower member, which are members to be welded, by consumable electrode arc welding while moving a torch tip along a groove between the upper member and the lower member. The groove is formed by an inclined surface inclined with respect to the horizontal direction of the upper member, a horizontal surface formed along the horizontal direction of the lower member, and a surface of a backing strip covering a gap between the upper member and the lower member. The welding system includes a control device that controls the operation of the welding robot. After forming a first welding bead so as to cover the surface of the backing strip, the control device forms a welding bead layer composed of a plurality of welding beads so as to be stacked in the vertical direction from the horizontal surface toward the inclined surface, and sequentially repeats this from the end side in the depth direction of the groove to the opening edge of the groove, so as to form a multi-layered internal welding part composed of a plurality of the welding bead layers and a surface layer welding part covering the internal welding part between the upper member and the lower member. The control device controls the operation of the welding robot. Among the welding beads constituting each welding bead layer, a first angle of the torch tip with respect to the horizontal direction when forming a lower layer bead that contacts the horizontal surface is larger than a second angle of the torch tip with respect to the horizontal direction when forming an upper layer bead that contacts the inclined surface, and a third angle with respect to the horizontal direction when forming an intermediate bead between the lower layer bead and the upper layer bead is set to be an intermediate angle between the first angle and the second angle.

[0007] According to the present invention, the control device controls the operation of the welding robot such that a first angle of the torch tip with respect to the horizontal direction when forming the lower layer bead in contact with the horizontal plane is larger than a second angle of the torch tip with respect to the horizontal direction when forming the upper layer bead in contact with the inclined plane. Thereby, with respect to the horizontal plane of the lower member, the angle of the torch tip is the first angle larger than the second angle to form the lower layer bead, so that the penetration of the lower layer bead into the horizontal plane can be stabilized. On the other hand, with respect to the inclined plane of the upper member, the angle of the torch tip is the second angle smaller than the first angle to form the upper layer bead, so that the penetration of the upper layer bead into the inclined plane can be stabilized. Further, since the control device is set such that a third angle when forming the intermediate bead is an intermediate angle between the first angle and the second angle, an intermediate bead having a stable shape can be formed.

[0008] In a more preferable aspect, the first angle of each of the welding bead layers is set to the same angle, and the second angle of each of the welding bead layers is set to the same angle. According to this aspect, since the first angle of each welding bead layer is set to the same angle, the penetration of the lower layer bead of each welding bead layer into the horizontal plane of the lower member can be stabilized. Since the second angle of each welding bead layer is set to the same angle, the penetration of the upper layer bead of each welding bead layer into the inclined plane of the upper member can be stabilized.

[0009] In a more preferable aspect, the initial angle of the torch tip with respect to the horizontal direction when forming the first-pass welding bead is equal to or greater than the third angle. According to this aspect, the penetration of the first-pass welding bead can be stabilized with respect to each of the inclined plane of the upper member, the horizontal plane of the lower member, and the surface of the backing plate, and the shape of the first-pass welding bead can also be stabilized. In addition, when forming the first-pass welding bead, it becomes easier to insert the torch tip to the bottom of the groove. More preferably, the initial angle is smaller than the inclination angle of the inclined plane of the upper member with respect to the horizontal direction. Thereby, it becomes easier to smoothly insert and move the torch tip into the groove, and stable welding can be performed.

[0010] In a more preferred embodiment, the control device causes the welding robot to form the internal weld portion such that the cross-sectional area of the first weld bead is larger than the cross-sectional area of each weld bead in each weld bead layer. According to this embodiment, by making the cross-sectional area of the first weld bead larger than the cross-sectional area of each weld bead in the weld bead layer, heat from the melted welding material can be efficiently input into the upper member and the lower member at the start of welding. As a result, the portion including the inclined surface of the upper member and the portion including the horizontal surface of the lower member can be melted, improving the welding strength between the upper member and the lower member and enhancing the quality of the welding.

[0011] In a more preferred embodiment, the upper member is an upper steel pipe column, the lower member is a lower steel pipe column, the welding robot includes an articulated robot body and a carriage that travels on a linear rail extending in the horizontal direction, and the control device controls the operation of the welding robot to weld the upper steel pipe column and the lower steel pipe column along the groove while causing the carriage to travel along the rail and moving the torch tip by the operation of the robot body.

[0012] According to this embodiment, the control device can stably weld the upper steel pipe column and the lower steel pipe column along the groove while causing the carriage to travel along the rail and moving the torch tip by the operation of the robot body.

Advantages of the Invention

[0013] According to the present invention, stable-quality welding can be performed even when a multi-layered weld portion is formed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Embodiments for Carrying Out the Invention

[0015] Hereinafter, with reference to the drawings, the welding system 100 according to the embodiments of the present invention will be described below.

[0016] In the present embodiment, the welding system 100 is a system for welding the lower steel pipe column 1A and the upper steel pipe column 1B as the upper member and the lower member to be welded. As shown in FIG. 1, the column 1 is a steel pipe column and is composed of the lower steel pipe column 1A and the upper steel pipe column 1B. A horizontal plane 14 formed along the horizontal direction is formed at the upper end edge of the lower steel pipe column 1A. An inclined surface 15 inclined with respect to the horizontal direction is formed at the lower end edge of the upper steel pipe column 1B. By supplying the molten welding wire W to the groove 1C between the lower steel pipe column 1A and the upper steel pipe column 1B, the lower steel pipe column 1A and the upper steel pipe column 1B are integrated. The outer surfaces of the lower steel pipe column 1A and the upper steel pipe column 1B are in the shape of a square tube and are formed by four flat portions 10a and four curved portions 10b. Specifically, between the flat portions 10a, four curved portions 10b having a surface curved with a predetermined radius of curvature are formed so as to connect them. Note that the upper steel pipe column 1B and the lower steel pipe column 1A are not limited to the square-shaped steel pipe columns shown in FIGS. 1 and 2, etc. For example, they may be polygonal steel pipe columns other than a square (specifically, a polygonal steel pipe having three or more sides), or may be cylindrical steel pipes.

[0017] At predetermined positions on the flat portions 10a of the outer surfaces of the lower steel pipe column 1A and the upper steel pipe column 1B, a plurality (here, four) of erection pieces 2 are welded. These erection pieces 2 are provided to temporarily fix the adjacent lower steel pipe column 1A and upper steel pipe column 1B vertically. A temporary fixing jig 3 is attached to two erection pieces 2 arranged vertically.

[0018] The temporary fixing jig 3 extends in the vertical direction. The upper end is fastened to the upper erection piece 2 using bolts 4 or the like, and the lower end is fastened to the lower erection piece 2 using bolts 4 or the like. Although detailed description is omitted here, the temporary fixing jig 3 may be configured to be adjustable in the distance between two erection pieces 2 arranged vertically. Thereby, it is possible to adjust the gap between the lower steel pipe column 1A and the upper steel pipe column 1B, and it is also possible to adjust the inclination of the upper steel pipe column 1B. Note that the temporary fixing jig 3 is removed from the erection piece 2 when the welding of the butting portion of the lower steel pipe column 1A and the upper steel pipe column 1B is completed, or even during the welding of the butting portion, when the joining strength between the lower steel pipe column 1A and the upper steel pipe column 1B becomes large enough to support the building under construction.

[0019] Furthermore, in the present embodiment, a backing strip 31 (see FIGS. 2 and 4A) is attached along the circumferential direction to the inner wall surface of the lower steel pipe column 1A. For example, the backing strip 31 protrudes upward in the vertical direction (the longitudinal direction of the lower steel pipe column 1A) from the horizontal plane (upper end edge surface) 23 of the lower steel pipe column 1A. When the upper steel pipe column 1B is arranged on the lower steel pipe column 1A, the protruding portion of the backing strip 31 is inserted into the upper steel pipe column 1B. In this way, the groove 1C is formed by the inclined surface (lower end edge surface) 15 inclined with respect to the horizontal direction of the upper steel pipe column 1B, the horizontal plane formed along the horizontal direction of the lower steel pipe column 1A, and the surface of the backing strip covering the gap between the upper member and the lower member. Since the gap between the upper steel pipe column 1B and the lower steel pipe column 1A can be covered by the backing strip 31, it is possible to prevent the molten welding material from entering the inside of the steel pipe column 1 during welding.

[0020] The welding robot 80 is provided with a control device 70. The control device 70 supplies the welding wire W from the tip of the torch 88 to the groove 1C between the lower steel pipe column 1A and the upper steel pipe column 1B, and moves the torch 88 along the groove 1C. At this time, by generating an arc discharge between the wire W and the column 1, the lower steel pipe column 1A and the upper steel pipe column 1B are welded while melting the tip of the welding wire W. When welding the lower steel pipe column 1A and the upper steel pipe column 1B as in the present embodiment, the temporary fixing jig 3 is sandwiched and welded along the welding path along the groove 1C. For this reason, the welding by the welding robot 80 is temporarily interrupted, the posture of the welding robot 80 is changed, and the welding is resumed. The welding between the lower steel pipe column 1A and the upper steel pipe column 1B is repeatedly performed so as to reciprocate along the welding path along the groove 1C. At the start of welding, since the arc discharge is more likely to be stably generated when the tip of the wire W has a sharp shape, the tip of the wire W is cut by the wire cutting device 35.

[0021] The welding robot 80 is guided along a rail 34 attached to the reinforcing plate 33. The reinforcing plate 33 is supported by a pair of support members 32, 32 attached to the outer surface of the lower steel pipe column 1A.

[0022] The support member 32 is detachably supported on the outer surface of the lower steel pipe column 1A via a fixing unit 21. The pair of support members 32, 32 are attached to the lower steel pipe column 1A so as to sandwich the column 1. The pair of reinforcing plates 33, 33 are passed for each pair of support members 32, 32 so as to sandwich the column 1. Each rail 34 is a linear rail, is attached for each reinforcing plate 33, and extends horizontally so as to face the steel pipe column 1 (a pair of steel pipe columns (1A, 1B)). Each rail 34 is a linear guide and guides the traveling of each welding robot 80.

[0023] Next, the welding system 10 will be described. In the present embodiment, the welding system 10 includes a welding robot 80 and a control device 70. The welding robot 80 supplies a welding wire W from a feeding device (not shown) from the tip of a torch 88 to the upper steel pipe column 1B, the lower steel pipe column 1A, and the groove 1C, and moves the torch 88 along the groove 1C. It includes an articulated robot body 80A and a carriage 90 that travels on a linear rail 34 extending in the horizontal direction. The robot body 80A uses the wire W as a consumable electrode for welding, and may include a feeding device that feeds the welding wire W to the torch 88.

[0024] As shown in FIG. 1, the robot body 80A is placed on the rail 34 and mounted on a carriage 90 that travels along the rail 34. A cable 89 that sends power and control signals for the travel of the carriage 90 and the operation of the robot body 80A is connected to the carriage 90. The robot body 80A includes a swivel base 82 that is arranged on the carriage 90 and can swivel around a shaft extending in the vertical direction, and a base portion 83 that is arranged on the swivel base 82 and extends upward.

[0025] Furthermore, the robot body 80A includes a first arm 84 that is arranged on the base portion 83 and can rotate around a shaft extending in the horizontal direction, and a second arm 85 that is connected to the first arm 84 and can rotate around a shaft extending in the horizontal direction.

[0026] The second arm 85 includes an arm body 86 that rotates along its axial direction, and a third arm 87 is rotatably attached to the tip of the arm body 86. A torch 88 is attached to the third arm 87, and the welding torch 88 is connected to a cable 99.

[0027] The robot body 80A is moved to a predetermined position by the carriage 90, and by driving the swivel base 82, the first arm 84, the second arm 85, and the third arm 87, the tip of the torch 88 is placed at a desired position of the groove 1C of the lower steel pipe column 1A and the upper steel pipe column 1B for welding.

[0028] The carriage 90 is a device that performs relative movement between the welding robot 80 and a pair of steel pipe columns (1A, 1B) during welding. The welding robot 80 is mounted on the carriage 90, and the carriage 90 travels (moves linearly) along the rail 34 extending in the horizontal direction. Specifically, a motor (not shown) is built into the carriage 90, and the carriage 90 can move to a predetermined position on the rail 34 according to a control signal from the control device 70 via the cable 89.

[0029] In the present embodiment, as shown in FIG. 3, in regions A and B where the space between the opposing rails 34, 34 is partitioned by a boundary line, the respective articulated robots (welding robots) 80 are set to perform welding. When welding with each articulated robot 80 within the set regions A and B, while moving the torch 88 along the weld line of the groove 1C, a welding material is supplied from the tip of the torch 88 to the groove 1C. Specifically, the groove 1C (weld line) that circumscribes along the circumferential direction is divided into four welding sections 1L, 1R, 2L, and 2R. In the present embodiment, the weld line of the groove 1C is divided in four sections sandwiching the erection piece 2.

[0030] When welding for each of the welding sections 1L, 1R, 2L, and 2R shown in FIG. 3, for example, when the erection piece 2 at the boundary between the welding sections 1L and 1R is passed by the welding robot 80 (robot body 80A), the welding is temporarily interrupted and the welding conditions are changed, so that welding can be performed more reasonably.

[0031] Here, while moving the torch 88 a plurality of times along the weld line of the groove 1C, a welding material is supplied to form a welded portion (bead) that becomes a multi-layer build-up portion. At this time, since the position of the welding point located at the tip of the torch 88 and the direction of the torch 88 are different for each movement, it is suitable to perform such welding with the articulated robot body 80A. Also, in each welding section, the number of times the torch 88 is moved to build up the welding material is the same.

[0032] In this embodiment, welding of the upper steel pipe column 1B and the lower steel pipe column 1A is performed while the tips of the torches 88 of a pair of welding robots 80, 80 face each other across the central axis of the steel pipe column 1. Thereby, heat during welding to the upper steel pipe column 1B and the lower steel pipe column 1A can be symmetrically input across the central axis of the steel pipe column 1. As a result, distortion and the like of the central axis of the steel pipe column 1 can be suppressed.

[0033] In this embodiment, running control of the carriage 81, drive control of the robot main body 80A, welding according to welding conditions by the torch 98, and the like are performed by the control device 70. Further, in order to execute the running control of the carriage 81 and the drive control of the robot main body 80A, the posture of the robot main body 80A and the position of the carriage 81 are previously taught using a teaching pendant (not shown), and control of the following welding robot 80 is set.

[0034] As shown in FIG. 4A, by the control device 70 controlling the welding robot 80, the first welding bead B0 is formed so as to cover the surface 31a of the backing washer 31. Here, when forming the first welding bead B0 in the cross section of the groove 1C, the first welding bead B0 is formed while maintaining the first angle (tilt angle) θ0 of the torch tip with respect to the horizontal direction.

[0035] As shown in FIG. 4B, by the control device 70 controlling the welding robot 80, a welding bead layer B1 composed of a plurality of welding beads (B11, B12) is formed so as to be stacked in the vertical direction from the horizontal plane 14 of the lower steel pipe column 1A toward the inclined surface 15 of the upper steel pipe column 1B. The welding bead layer B1 is formed in the order of the lower bead B11 and the upper bead B12 so as to cover the first welding bead B0. Specifically, the control device 70 controls the operation of the welding robot 80 such that a first angle θ1 of the torch tip with respect to the horizontal direction when forming the lower bead B11 in contact with the horizontal plane 14 among the welding beads constituting the welding bead layer B1 is larger than a second angle θ2 of the torch tip with respect to the horizontal direction when forming the upper bead B12 in contact with the inclined surface 15. For example, the first angle θ1 is in the range of 30° to 45°, and the second angle θ2 is in the range of 5° to 25°.

[0036] Next, as shown in FIG. 4C, the control device 70 controls the welding robot 80 to form a weld bead layer B2 composed of a plurality of weld beads (B21 to B23) so as to be stacked in the vertical direction from the horizontal plane 14 of the lower steel pipe column 1A toward the inclined surface 15 of the upper steel pipe column 1B. The weld bead layer B2 forms the lower bead B21, the intermediate bead B22, and the upper bead B23 in this order so as to cover the weld bead layer B1.

[0037] Specifically, the control device 70 controls the operation of the welding robot 80 so that the first angle θ1 of the torch tip with respect to the horizontal direction when forming the lower bead B21 that contacts the horizontal plane 14 is larger than the second angle θ2 of the torch tip with respect to the horizontal direction when forming the upper bead B23 that contacts the inclined surface 15 among the weld beads constituting the weld bead layer B2. Further, the third angle θ3 with respect to the horizontal direction when forming the intermediate bead B22 between the lower bead B21 and the upper bead B23 is set to be an intermediate angle between the first angle θ1 and the second angle θ2. For example, the third angle θ3 is in the range of 20° to 30°.

[0038] Next, as shown in FIG. 4D, the control device 70 controls the welding robot 80 to form a weld bead layer B3 composed of a plurality of weld beads (B31 to B34) so as to be stacked in the vertical direction from the horizontal plane 14 of the lower steel pipe column 1A toward the inclined surface 15 of the upper steel pipe column 1B. The weld bead layer B3 forms the lower bead B31, the intermediate beads B32, B33, and the upper bead B34 in this order so as to cover the weld bead layer B2.

[0039] Specifically, the control device 70 controls the operation of the welding robot 80 such that the first angle θ1 of the torch tip with respect to the horizontal direction when forming the lower bead B31 that contacts the horizontal plane 14 among the welding beads constituting the weld bead layer B3 is greater than the second angle θ2 of the torch tip with respect to the horizontal direction when forming the upper bead B34 that contacts the inclined plane 15. Further, the third angle θ3 with respect to the horizontal direction when forming the intermediate beads B32 and B33 between the lower bead B31 and the upper bead B34 is set to be an intermediate angle between the first angle θ1 and the second angle θ2.

[0040] In this way, by sequentially repeating the formation of the weld bead layers B1 to B3 from the end side in the depth direction of the groove 1C to the opening edge of the groove 1C, a multi-layered internal weld portion BL composed of a plurality of weld bead layers B1 to B3 is formed between the upper steel pipe column 1B and the lower steel pipe column 1A.

[0041] Next, as shown in FIG. 4E, the control device 70 controls the welding robot 80 to form a surface weld portion CL that covers the internal weld portion BL. A surface weld portion CL composed of a plurality of weld beads C1 to C5 is formed so as to be stacked in the vertical direction from the horizontal plane 14 of the lower steel pipe column 1A toward the inclined plane 15 of the upper steel pipe column 1B. The surface weld portion CL is formed in the order of the weld beads C1 to C5 so as to cover the internal weld portion BL. The angle with respect to the horizontal direction when forming the weld beads C1 to C5 is not particularly limited as long as it covers the internal weld portion BL and there are no welding defects such as sagging of the weld beads C1 to C5. Also, since the size of the groove 1C changes according to the wall thicknesses of the upper steel pipe column 1B and the lower steel pipe column 1A, the number of weld bead layers of the internal weld portion BL and the number of weld beads of the surface weld portion CL can be set according to the size of this groove 1C.

[0042] In addition, in this embodiment, the first angle θ1 of each welding bead layer B1 to B3 is set to the same angle, and the second angle θ2 of each welding bead layer B1 to B5 is set to the same angle. Since the first angle θ1 of each welding bead layer B1 to B3 is set to the same angle in this way, the penetration of the lower bead B11, B21, B31 of each welding bead layer B1 to B3 with respect to the horizontal plane 14 of the lower steel pipe column 1A can be stabilized. On the other hand, since the second angle θ2 of each welding bead layer B1 to B3 is set to the same angle, the penetration of the upper bead B12, B23, B34 of each welding bead layer B1 to B3 with respect to the inclined plane 15 of the upper steel pipe column 1B can be stabilized.

[0043] Furthermore, the first angle θ0 with respect to the horizontal direction of the torch tip when forming the first welding bead B0 is equal to or greater than the third angle. Thereby, the penetration of the first welding bead B0 can be stabilized with respect to the inclined plane 15 of the upper steel pipe column 1B, the horizontal plane 14 of the lower steel pipe column 1A, and the surface 31a of the backing plate 31, and the shape of the first welding bead B0 can also be stabilized. In addition, when forming the first welding bead B0, it becomes easier to insert the torch tip to the bottom of the groove 1C. More preferably, the first angle θ0 is smaller than the inclination angle of the inclined plane 15 of the upper steel pipe column 1B with respect to the horizontal direction. Thereby, it becomes easier to smoothly insert and move the torch tip into the groove 1C, and stable welding can be performed.

[0044] Furthermore, in this embodiment, the control device 70 causes the welding robot 80 to form the internal weld portion BL such that the cross-sectional area of the first-pass weld bead B0 is larger than the cross-sectional areas of the respective weld beads B11 to B12, B21 to B23, and B31 to B34 of each weld bead layer B1 to B3. Specifically, when forming the first-pass weld bead B0, compared with the case of forming other weld beads, the control device 70 controls the welding robot 80 so as to satisfy at least one of the following: (1) increasing the current supplied to the torch 88; (2) increasing the voltage applied to the torch 88; (3) decreasing the moving speed of the torch 88. By the conditions (1) and (2), the feeding amount of the wire W supplied per unit time can be increased. In this way, at the start of welding, heat from the melted welding material can be efficiently input into the upper steel pipe column 1B and the lower steel pipe column 1A. As a result, the portion including the inclined surface 15 of the upper steel pipe column 1B and the portion including the horizontal surface 14 of the lower steel pipe column 1A can be melted, improving the welding strength between the upper steel pipe column 1B and the lower steel pipe column 1A and enhancing the welding quality.

[0045] Thus, according to this embodiment, with respect to the horizontal surface 14 of the lower steel pipe column 1A, the lower layer beads B11, B21, and B31 are formed at the first angle θ1 that is larger than the second angle θ2 with respect to the tip of the torch, so that the penetration of the lower layer beads B11, B21, and B31 into the horizontal surface 14 of the lower steel pipe column 1A can be stabilized. On the other hand, with respect to the inclined surface 15 of the upper steel pipe column 1B, the upper layer beads B12, B23, and B34 are formed at the second angle θ2 that is smaller than the first angle θ1 with respect to the tip of the torch, so that the penetration of the upper layer beads 12, B23, and B34 into the inclined surface 15 of the upper steel pipe column 1B can be stabilized.

[0046] Furthermore, since the third angle θ3 when forming the intermediate beads B22, B32, and B33 is set to be an intermediate angle between the first angle θ1 and the second angle θ2 in the control device 70, intermediate beads B22, B32, and B33 with a stable shape can be formed. Note that the third angle θ3 when forming the intermediate beads B22, B32, and B33 may be set to the same angle.

[0047] As described above in detail, the embodiments of the present invention are not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims.

[0048] In this embodiment, the lower steel pipe column and the upper steel pipe column are exemplified as the upper member and the lower member which are members to be welded. However, the members to be welded are not limited to this, and may be thick steel plates arranged in the vertical direction.

Explanation of reference numerals

[0049] 1A: Lower steel pipe column (lower member), 1B: Upper steel pipe column (upper member), 1C: Groove, 14: Horizontal plane, 15: Inclined plane, 31: Backing, 70: Control device, 80: Welding robot, 80A: Robot body, 88: Torch, 90: Carriage, 100: Welding system, B0: First welding bead, B1 to B3: Welding bead layers, B11, B21, B31: Lower layer beads (welding beads), B22, B32, B33: Intermediate beads (welding beads), B12, B23, B34: Upper layer beads (welding beads), BL: Internal welding part, CL: Surface layer welding part, θ0: First angle, θ1: First angle, θ2: Second angle, θ3: Third angle

Claims

1. A welding system comprising a welding robot that performs welding of an upper member and a lower member, which are members to be welded, by consumable electrode arc welding while moving a torch tip along a groove between the upper member and the lower member, wherein the groove is formed by an inclined surface inclined with respect to the horizontal direction of the upper member, a horizontal surface formed along the horizontal direction of the lower member, and a surface of a backing bar covering a gap between the upper member and the lower member, the welding system includes a control device that controls the operation of the welding robot, after forming a first welding bead so as to cover the surface of the backing bar, the control device controls the operation of the welding robot to sequentially repeat, from the end side in the depth direction of the groove to the opening edge of the groove, forming a welding bead layer composed of a plurality of welding beads so as to be stacked in the vertical direction from the horizontal surface toward the inclined surface, thereby forming, between the upper member and the lower member, a multi-layered internal welded portion composed of a plurality of the welding bead layers and a surface welded portion covering the internal welded portion, in the control device, a first angle with respect to the horizontal direction of the torch tip when forming a lower layer bead that contacts the horizontal surface among the welding beads constituting each welding bead layer is larger than a second angle with respect to the horizontal direction of the torch tip when forming an upper layer bead that contacts the inclined surface, and a third angle with respect to the horizontal direction when forming an intermediate bead between the lower layer bead and the upper layer bead is set to be an intermediate angle between the first angle and the second angle. A welding system characterized by this.

2. The welding system according to claim 1, wherein the first angle of each welding bead layer is set to the same angle, and the second angle of each welding bead layer is set to the same angle.

3. The welding system according to claim 1, wherein a first angle with respect to the horizontal direction of the torch tip when forming the first welding bead is equal to or greater than the third angle.

4. The welding system according to claim 1, wherein the control device causes the welding robot to form the internal welded portion such that a cross-sectional area of the first welding bead is larger than a cross-sectional area of each welding bead of each welding bead layer.

5. The upper member is an upper steel pipe column, and the lower member is a lower steel pipe column. The welding robot includes an articulated robot body and a carriage that travels on a linear rail extending in the horizontal direction. The control device controls the operation of the welding robot so as to weld the upper steel pipe column and the lower steel pipe column along the groove while moving the carriage along the rail and moving the tip of the torch by the operation of the robot body. The welding system according to claim 1, characterized in that.

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