Mash seam welding device

Abstract

A mash seam welding device (100) has: a first electrode wheel (1); a second electrode wheel (2); and an electrode wheel pressing unit (3). The second electrode wheel (2) faces the first electrode wheel (1). The electrode wheel pressing unit (3) presses the first electrode wheel (1) against a material (90) to be welded along a first direction (101) from the first electrode wheel (1) toward the second electrode wheel (2). The electrode wheel pressing unit (3) has: a first servo motor (11); a first feed screw section (14); an electrode wheel support section (15); and an electrode wheel guide section (16). The central axis of the first feed screw section (14) intersects the first electrode wheel (1).

Description

Mash seam welding equipment

[0001] The present disclosure relates to a mash seam welding apparatus.

[0002] In a mash seam welding device that welds two or more overlapping workpieces, the workpieces are welded using electrode wheels. Specifically, the workpieces are sandwiched between two electrode wheels from above and below. The workpieces are welded by applying pressure to them using the two electrode wheels and moving the two electrode wheels.

[0003] The joining device described in International Publication No. 2010 / 004657 (Patent Document 1) includes a pair of upper and lower electrode wheels and an electrode wheel pressing device, which is a hydraulic cylinder.

[0004] International Publication No. 2010 / 004657

[0005] The joining device described in Patent Document 1 uses a hydraulic cylinder as the electrode wheel pressing device, which requires many parts to constitute a hydraulic circuit, and therefore increases the frequency of part replacement, making the joining device difficult to maintain.

[0006] The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a mash seam welding device that can improve maintainability.

[0007] A mash seam welding apparatus according to the present disclosure welds overlapping workpieces by sandwiching the workpieces between a first electrode wheel and a second electrode wheel and supplying a current between the first electrode wheel and the second electrode wheel. The mash seam welding apparatus includes a first electrode wheel, a second electrode wheel, and an electrode wheel pressurizing unit. The second electrode wheel faces the first electrode wheel. The electrode wheel pressurizing unit presses the first electrode wheel against the workpieces along a first direction from the first electrode wheel to the second electrode wheel. The electrode wheel pressurizing unit includes a first servo motor, a first lead screw unit, an electrode wheel support unit, and an electrode wheel guide unit. The first lead screw unit converts rotation of the first servo motor into linear motion along the first direction. The electrode wheel support unit connects the first lead screw unit and the first electrode wheel. The electrode wheel guide unit guides the electrode wheel support unit and the first electrode wheel along the first direction. The central axis of the first lead screw portion intersects with the first electrode wheel.

[0008] In the mash seam welding device according to the present disclosure, the electrode wheel pressurizing unit has a first servo motor. This reduces the number of parts compared to when a hydraulic cylinder is used as a device for pressurizing the electrode wheel, thereby improving maintainability.

[0009] 6 is a schematic front view showing the configuration of a mash seam welding apparatus according to embodiment 1. FIG. 7 is a schematic partial cross-sectional view showing the configuration of a pressure unit. FIG. 8 is a schematic partial cross-sectional view showing the configuration of an electrode wheel pressure unit. FIG. 9 is a schematic partial cross-sectional view showing the configuration of a roll pressure unit. FIG. 10 is a schematic bottom view showing the configuration of a fixed frame. FIG. 11 is an enlarged schematic side view showing the configuration of an electrode wheel adjustment unit. FIG. 12 is a schematic cross-sectional view taken along line VII-VII of FIG. 6. FIG. 13 is a schematic first longitudinal cross-sectional view showing the configuration of the electrode wheel adjustment unit. FIG. 14 is a schematic cross-sectional view taken along line IX-IX of FIG. 6. FIG. 15 is a schematic cross-sectional view taken along line IX-IX of FIG. 16. FIG. 17 is a schematic cross-sectional view taken along line IX-IX of FIG. 17. FIG. 18 is an enlarged schematic view showing the configuration of a mash seam welding apparatus according to embodiment 1. FIG. 19 is a block diagram showing the configuration of a mash seam welding apparatus according to embodiment 1. FIG. 19 is a flow chart showing the operation of the mash seam welding apparatus according to embodiment 1. FIG. 11 is an enlarged schematic view showing the process of preparing materials to be welded. FIG. 12 is an enlarged schematic view showing a state in which materials to be welded have reached a first detection area. FIG. 13 is an enlarged schematic view showing the process of lowering a first electrode wheel. 1 is an enlarged schematic view showing a state in which the workpiece has reached the second detection area. FIG. 2 is an enlarged schematic view showing a step of lowering the first pressure roll. FIG. 3 is an enlarged schematic view showing how the workpiece is welded and rolled. FIG. 4 is a partial cross-sectional schematic view illustrating a force acting on an electrode wheel guide portion when a first electrode wheel is pressed against a workpiece. FIG. 5 is an enlarged schematic view showing a state in which the first electrode wheel and the second electrode wheel are in contact. FIG. 6 is an enlarged schematic view showing how a workpiece is inserted between the first electrode wheel and the second electrode wheel that are in contact with each other. FIG. 7 is a schematic view illustrating a force received by the first electrode wheel when a workpiece is inserted between the first electrode wheel and the second electrode wheel that are in contact with each other. FIG. 8 is a schematic view showing a configuration of a mash seam welding apparatus according to a modified example of embodiment 1. FIG. 9 is an enlarged schematic rear view showing the configuration of a mash seam welding apparatus according to embodiment 2. FIG. 10 is an enlarged schematic side view showing the configuration of a mash seam welding apparatus according to embodiment 2. FIG. 11 is an enlarged schematic rear view showing the configuration of a mash seam welding apparatus according to a modified example of embodiment 2. Fig. 1 is an enlarged schematic side view showing the configuration of a mash seam welding apparatus according to a modified example of embodiment 2. Fig. 2 is an enlarged schematic side view showing the configuration of a mash seam welding apparatus according to embodiment 3. Fig. 3 is a block diagram showing the outline of the configuration of the mash seam welding apparatus according to embodiment 3.1 is a flow chart illustrating an outline of an operation for adjusting the rotation speed of a third servo motor; FIG. 2 is a schematic diagram illustrating wear of a first electrode wheel; FIG. 3 is a first enlarged schematic cross-sectional view illustrating a configuration of a mash seam welding apparatus according to a fourth embodiment; FIG. 4 is a second enlarged schematic cross-sectional view illustrating a configuration of a mash seam welding apparatus according to a fourth embodiment;

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0011] First Embodiment <Configuration of Mash Seam Welding Apparatus> First, the configuration of a mash seam welding apparatus 100 according to a first embodiment will be described.

[0012] As shown in FIG. 1, the mash seam welding apparatus 100 mainly includes a first electrode wheel 1, a second electrode wheel 2, an electrode wheel support base 4, a first pressure roll 5, a second pressure roll 6, a roll support base 8, an electrode wheel pressure unit 3, a roll pressure unit 7, and a power source (not shown).

[0013] Each of the first electrode wheel 1 and the second electrode wheel 2 is an electrode that welds the workpiece 90. The second electrode wheel 2 faces the first electrode wheel 1. The direction from the first electrode wheel 1 to the second electrode wheel 2 is defined as a first direction 101. The first pressure roll 5 and the second pressure roll 6 roll the welded workpiece 90. The electrode wheel support base 4 supports the second electrode wheel 2. The roll support base 8 supports the second pressure roll 6. The electrode wheel pressure unit 3 presses the first electrode wheel 1 against the workpiece 90 along the first direction 101. The roll pressure unit 7 presses the first pressure roll 5 against the workpiece 90 along the first direction 101.

[0014] The first electrode wheel 1 is attached to an electrode wheel pressure unit 3. The second electrode wheel 2 is positioned in a first direction 101 relative to the first electrode wheel 1. The second electrode wheel 2 is attached to an electrode wheel support base 4. A power source (not shown) supplies current between the first electrode wheel 1 and the second electrode wheel 2.

[0015] The first pressure roll 5 and the first electrode wheel 1 are aligned along the second direction 102. Specifically, the first electrode wheel 1 is positioned in the second direction 102 relative to the first pressure roll 5. The second direction 102 is the direction in which the first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6 move when welding the workpieces 90. The first pressure roll 5 is attached to a roll pressure unit 7.

[0016] The second pressure roll 6 faces the first pressure roll 5. The second pressure roll 6 is located in a first direction 101 relative to the first pressure roll 5. The second pressure roll 6 and the second electrode wheel 2 are aligned along a second direction 102. Specifically, the second electrode wheel 2 is located in the second direction 102 relative to the second pressure roll 6.

[0017] 1 , the mash seam welding apparatus 100 has a fixed frame 70, a carriage frame 9, a plurality of support wheels 80, and a frame drive unit (not shown). The fixed frame 70 supports each of the electrode wheel pressure unit 3 and the roll pressure unit 7. The fixed frame 70 surrounds each of the electrode wheel pressure unit 3 and the roll pressure unit 7. The carriage frame 9 supports each of the fixed frame 70, the electrode wheel support base 4, and the roll support base 8.

[0018] The carriage frame 9 has an upper frame portion 95, a lower frame portion 96, and a connecting portion 97. The upper frame portion 95 supports the fixed frame 70. The upper frame portion 95 extends along a second direction 102.

[0019] The lower frame portion 96 faces the upper frame portion 95. The lower frame portion 96 is positioned in a first direction 101 relative to the upper frame portion 95. The lower frame portion 96 supports each of the electrode wheel support base 4 and the roll support base 8. The lower frame portion 96 extends along a second direction 102.

[0020] The connecting portion 97 connects the upper frame portion 95 and the lower frame portion 96. The connecting portion 97 is located in the second direction 102 relative to each of the upper frame portion 95 and the lower frame portion 96. The connecting portion 97 extends along the first direction 101.

[0021] Each of the multiple support wheels 80 is attached to a bottom 85 of the carriage frame 9. The bottom 85 of the carriage frame 9 is composed of a lower frame portion 96 and a connecting portion 97. The bottom 85 is the portion that faces a floor (not shown) on which the mash seam welding apparatus 100 is placed.

[0022] Each of the plurality of support wheels 80 contacts the floor. Each of the plurality of support wheels 80 supports the carriage frame 9. Each of the plurality of support wheels 80 is configured to be rotatable on its own axis. A frame drive unit (not shown) applies a force to the carriage frame 9 in a direction parallel to the second direction 102. Some of the plurality of support wheels 80 are attached to the lower frame portion 96. Some of the plurality of support wheels 80 are attached to the connection portion 97.

[0023] As shown in Figure 2, the electrode wheel pressure unit 3 has a first servo motor 11, a first reducer 12, a first coupling 13, a first feed screw unit 14, an electrode wheel support unit 15, and an electrode wheel guide unit 16.

[0024] The first servo motor 11 is located in a direction opposite to the first direction 101 with respect to the fixed frame 70. The first reducer 12 is attached to the first servo motor 11. The first servo motor 11 and the first reducer 12 are attached to the fixed frame 70. The first coupling 13 connects the first reducer 12 to the first lead screw unit 14. The first lead screw unit 14 converts the rotation of the first servo motor 11 into linear motion along the first direction 101. The first lead screw unit 14 extends along the first direction 101. The central axis of the first lead screw unit 14 is defined as a first central axis O1.

[0025] The electrode wheel support portion 15 connects the first lead screw portion 14 and the first electrode wheel 1. The first electrode wheel 1 is attached to the electrode wheel support portion 15. The electrode wheel guide portion 16 guides the electrode wheel support portion 15 and the first electrode wheel 1 along the first direction 101. The electrode wheel guide portion 16 is, for example, a linear guide.

[0026] The electrode wheel guide unit 16 has a first rail 31, a second rail 32, a first block 36, and a second block 37. The first rail 31 extends along a first direction 101. The second rail 32 is spaced apart from the first rail 31. The second rail 32 extends along the first direction 101. From another perspective, the extension direction of the second rail 32 is parallel to the extension direction of the first rail 31. The first rail 31 and the second rail 32 are aligned along the second direction 102.

[0027] The first blocks 36 are configured to be slidable on the first rail 31. The number of first blocks 36 is, for example, two. The second blocks 37 are configured to be slidable on the second rail 32. The number of second blocks 37 is, for example, two.

[0028] The first electrode wheel 1 has a first outer peripheral surface 33. The first outer peripheral surface 33 is a surface that comes into contact with the workpiece 90. As shown in Fig. 2 , the first outer peripheral surface 33 is circular when viewed in a direction perpendicular to each of the first direction 101 and the second direction 102. From another perspective, the outer shape of the first electrode wheel 1 is circular when viewed in a direction perpendicular to each of the first direction 101 and the second direction 102. The first central axis O1 intersects with the first outer peripheral surface 33.

[0029] The central axis of the first electrode wheel 1 is defined as a first rotation axis C1. The first electrode wheel 1 is configured to be rotatable around the first rotation axis C1. The first rotation axis C1 is perpendicular to each of the first direction 101 and the second direction 102. The direction in which the first rotation axis C1 extends is defined as a third direction 103. The first rotation axis C1 may be perpendicular to the first central axis O1. The first rotation axis C1 may intersect with the first central axis O1.

[0030] As shown in FIG. 2 , the roll pressure unit 7 has a second servo motor 41, a second reducer 42, a second coupling 43, a second feed screw unit 44, a roll support unit 45, and a roll guide unit 46.

[0031] The second servo motor 41 is located in a direction opposite to the first direction 101 with respect to the fixed frame 70. The second reducer 42 is attached to the second servo motor 41. The second servo motor 41 and the second reducer 42 are attached to the fixed frame 70. The second coupling 43 connects the second reducer 42 and the second lead screw unit 44. The second lead screw unit 44 converts the rotation of the second servo motor 41 into linear motion along the first direction 101. The second lead screw unit 44 extends along the first direction 101. The central axis of the second lead screw unit 44 is defined as a second central axis O2.

[0032] The roll support unit 45 connects the second feed screw unit 44 and the first pressure roll 5. The first pressure roll 5 is attached to the roll support unit 45. The roll guide unit 46 guides the roll support unit 45 and the first pressure roll 5 along the first direction 101. The roll guide unit 46 is, for example, a linear guide.

[0033] The roll guide unit 46 has a third rail 61, a fourth rail 62, a third block 66, and a fourth block 67. The third rail 61 extends along the first direction 101. The fourth rail 62 is spaced apart from the third rail 61. The fourth rail 62 extends along the first direction 101. From another perspective, the extension direction of the fourth rail 62 is parallel to the extension direction of the third rail 61. The third rail 61 and the fourth rail 62 extend along the second direction 102.

[0034] The third blocks 66 are configured to be slidable on the third rail 61. The number of third blocks 66 is, for example, two. The fourth blocks 67 are configured to be slidable on the fourth rail 62. The number of fourth blocks 67 is, for example, two.

[0035] The first pressure roll 5 has a second outer peripheral surface 34. The second outer peripheral surface 34 is a surface that comes into contact with the workpiece 90. As shown in Fig. 2, the second outer peripheral surface 34 is circular when viewed in a direction perpendicular to each of the first direction 101 and the second direction 102. From another perspective, the outer shape of the first pressure roll 5 is circular when viewed in a direction perpendicular to each of the first direction 101 and the second direction 102. The second central axis O2 intersects with the second outer peripheral surface 34.

[0036] The central axis of the first pressure roll 5 is a second rotation axis C2. The first pressure roll 5 is configured to be rotatable around the second rotation axis C2. The second rotation axis C2 is perpendicular to both the first direction 101 and the second direction 102. The second rotation axis C2 may be perpendicular to the second central axis O2. The second rotation axis C2 may intersect with the second central axis O2.

[0037] As shown in Fig. 3, the first feed screw portion 14 has a first screw shaft 18 and a first nut portion 19. The first feed screw portion 14 is, for example, a ball screw. The first screw shaft 18 is connected to the first reducer 12 via the first coupling 13. The first nut portion 19 is configured to be slidable on the first screw shaft 18. The first nut portion 19 is attached to the electrode wheel support portion 15. A portion of the first nut portion 19 is exposed from the electrode wheel support portion 15 in the direction opposite to the first direction 101.

[0038] The electrode wheel support portion 15 has a first movable frame 22, an electrode wheel adjustment portion 23, and an electrode wheel connection portion 24. The first movable frame 22 is attached to a first nut portion 19. The first movable frame 22 is surrounded by a fixed frame 70. The first movable frame 22 surrounds a first central axis O1. The central axis of the first movable frame 22 may overlap with the first central axis O1.

[0039] The electrode wheel guide portion 16 is attached to both the fixed frame 70 and the electrode wheel support portion 15. Specifically, a first rail 31 and a second rail 32 (see FIG. 2) are attached to the fixed frame 70. A first block 36 and a second block 37 (see FIG. 2) are attached to the first movable frame 22.

[0040] The electrode wheel adjustment unit 23 adjusts the position and attitude of the first electrode wheel 1. The electrode wheel adjustment unit 23 is attached to the first movable frame 22. The electrode wheel adjustment unit 23 is located in a first direction 101 relative to the first movable frame 22. The electrode wheel adjustment unit 23 is located outside the fixed frame 70. Specifically, the electrode wheel adjustment unit 23 is located in the first direction 101 relative to the fixed frame 70. Details of the electrode wheel adjustment unit 23 will be described later. The electrode wheel connection unit 24 connects the electrode wheel adjustment unit 23 and the first electrode wheel 1. When viewed in the second direction 102, the shape of the electrode wheel connection unit 24 is, for example, a C-shape.

[0041] 2 and 3 , the first center axis O1 intersects with the first electrode wheel 1. Specifically, the first center axis O1 intersects with the first outer peripheral surface 33. More specifically, the first center axis O1 intersects with a portion of the first outer peripheral surface 33 that contacts the workpiece 90. The first electrode wheel 1 is positioned in a first direction 101 with respect to the first lead screw portion 14.

[0042] As shown in Fig. 4, the second feed screw portion 44 has a second screw shaft 48 and a second nut portion 49. The second feed screw portion 44 is, for example, a ball screw. The second screw shaft 48 is connected to the second reducer 42 via a second coupling 43. The second nut portion 49 is configured to be slidable on the second screw shaft 48. The second nut portion 49 is attached to the roll support portion 45. A portion of the second nut portion 49 is exposed from the roll support portion 45 in the direction opposite to the first direction 101.

[0043] The roll support unit 45 has a second movable frame 52, a roll adjustment unit 53, and a roll connection unit 54. The second movable frame 52 is attached to the second nut unit 49. The second movable frame 52 is surrounded by a fixed frame 70. The second movable frame 52 surrounds a second central axis O2. The central axis of the second movable frame 52 may overlap with the second central axis O2.

[0044] The roll guide unit 46 is attached to both the fixed frame 70 and the roll support unit 45. Specifically, a third rail 61 and a fourth rail 62 (see FIG. 2) are attached to the fixed frame 70. A third block 66 and a fourth block 67 (see FIG. 2) are attached to the second movable frame 52.

[0045] The roll adjustment unit 53 adjusts the position and posture of the first pressure roll 5. The roll adjustment unit 53 is attached to the second movable frame 52. The roll adjustment unit 53 is located in the first direction 101 relative to the second movable frame 52. The roll adjustment unit 53 is located outside the fixed frame 70. Specifically, the roll adjustment unit 53 is located in the first direction 101 relative to the fixed frame 70. The configuration of the roll adjustment unit 53 is substantially the same as the configuration of the electrode wheel adjustment unit 23 (see FIG. 3 ). The roll connection unit 54 connects the roll adjustment unit 53 and the first pressure roll 5. When viewed in the second direction 102, the shape of the roll connection unit 54 is, for example, C-shaped.

[0046] 2 and 4 , the second central axis O2 intersects with the first pressure roll 5. Specifically, the second central axis O2 intersects with the second outer peripheral surface 34. More specifically, the second central axis O2 intersects with a portion of the second outer peripheral surface 34 that contacts the workpiece 90. The first pressure roll 5 is positioned in the first direction 101 with respect to the second feed screw portion 44.

[0047] FIG. 5 shows the configuration of the fixed frame 70 as viewed in the direction opposite to the first direction 101. As shown in FIG. 5, the fixed frame 70 has a top plate 76, an outer peripheral wall portion 78, and an intermediate wall portion 75. The electrode wheel pressure unit 3 and the roll pressure unit 7 (see FIG. 2) are attached to the top plate 76. The top plate 76 extends in a direction perpendicular to the first direction 101. A first through hole 83 and a second through hole 84 are provided in the top plate 76. The shaft of the first reducer 12 (see FIG. 2) is disposed in the first through hole 83. The shaft of the second reducer 42 (see FIG. 2) is disposed in the second through hole 84.

[0048] The outer peripheral wall portion 78 is continuous with the top plate 76. The outer peripheral wall portion 78 surrounds each of the electrode wheel pressure unit 3 and the roll pressure unit 7. The outer peripheral wall portion 78 has a first side wall portion 71, a second side wall portion 72, a third side wall portion 73, and a fourth side wall portion 74.

[0049] The first side wall portion 71 and the second side wall portion 72 face each other. The first rail 31, the second rail 32, the third rail 61, and the fourth rail 62 (see FIGS. 3 and 4) are attached to the first side wall portion 71. The third side wall portion 73 is continuous with the first side wall portion 71 and the second side wall portion 72. In the fixed frame 70, the fourth side wall portion 74 is opposite the third side wall portion 73.

[0050] The intermediate wall portion 75 is continuous with each of the first side wall portion 71 and the second side wall portion 72. The intermediate wall portion 75 is located between the third side wall portion 73 and the fourth side wall portion 74. The intermediate wall portion 75 divides the space surrounded by the outer peripheral wall portion 78 into a first space 88 and a second space 89. As shown in FIG. 2 , the electrode wheel pressure unit 3 is disposed in the first space 88. The roll pressure unit 7 is disposed in the second space 89.

[0051] Next, the electrode wheel adjustment unit 23 will be described in detail. As shown in Fig. 6 , the electrode wheel adjustment unit 23 has a position adjustment unit 26 and an attitude adjustment unit 27. The position adjustment unit 26 is attached to the first movable frame 22. The position adjustment unit 26 adjusts the position of the first electrode wheel 1 (see Fig. 2 ) in a direction perpendicular to the first direction 101. The attitude adjustment unit 27 is attached to the position adjustment unit 26. The attitude adjustment unit 27 adjusts the attitude of the first electrode wheel 1 in the circumferential direction 104 around the first central axis O1.

[0052] The first movable frame 22 has a main body 21 and a screw support 25. The main body 21 connects the first feed screw unit 14 and the electrode wheel adjustment unit 23. The screw support 25 is continuous with the main body 21.

[0053] 6, the position adjustment unit 26 includes a position adjustment plate 51, a plurality of first position adjustment screws 56, a plurality of second position adjustment screws 57, and a third position adjustment screw 58. The position adjustment plate 51 intersects with the first central axis O1. The position adjustment plate 51 is, for example, in the shape of a flat plate.

[0054] 7 , each of the plurality of first position adjustment screws 56 and the plurality of second position adjustment screws 57 is threaded into a female thread (not shown) provided in the screw support portion 25. The third position adjustment screw 58 is threaded into a female thread (not shown) provided in the position adjustment plate 51. The third position adjustment screw 58 may be fixed to the position adjustment plate 51. The third position adjustment screw 58 is located in an elongated hole 65 provided in the screw support portion 25. The elongated hole 65 extends along a third direction 103. The third position adjustment screw 58 is movable within the elongated hole 65 along the third direction 103.

[0055] Each of the multiple first position adjustment screws 56 extends along the third direction 103. The front end of each of the multiple first position adjustment screws 56 faces the position adjustment plate 51. As each of the multiple first position adjustment screws 56 moves along a direction parallel to the third direction 103, the multiple first position adjustment screws 56 press the position adjustment plate 51 along the direction parallel to the third direction 103.

[0056] Each of the plurality of second position adjustment screws 57 and the third position adjustment screws 58 extends along the second direction 102. The front end of each of the plurality of second position adjustment screws 57 faces the position adjustment plate 51. As each of the plurality of second position adjustment screws 57 moves along the second direction 102, each of the plurality of second position adjustment screws 57 presses against the position adjustment plate 51 along the second direction 102.

[0057] A nut 77 is attached to the third position adjustment screw 58. The nut 77 is in contact with the screw support portion 25. The nut 77 is located on the opposite side of the position adjustment plate 51 from the screw support portion 25. When the nut 77 rotates, the third position adjustment screw 58 moves in the direction opposite to the second direction 102. As a result, the position adjustment plate 51 is pulled in the direction opposite to the second direction 102.

[0058] As described above, by moving each of the multiple first position adjustment screws 56, the multiple second position adjustment screws 57, and the third position adjustment screw 58, the position adjustment unit 26 moves the first electrode wheel 1 along a direction perpendicular to the first central axis O1.

[0059] As shown in Fig. 8, the electrode wheel adjustment unit 23 has a plurality of first fixing screws 68. The plurality of first fixing screws 68 are screwed into the first movable frame 22. The position adjustment plate 51 is fastened to the first movable frame 22 by the plurality of first fixing screws 68. When the position adjustment unit 26 moves the first electrode wheel 1, the fastening between the position adjustment plate 51 and the first movable frame 22 is loosened. The cross section shown in Fig. 8 passes through the line VIII-VIII shown in Fig. 7.

[0060] 6 and 9, the attitude adjustment unit 27 includes an attitude adjustment plate 47 and a plurality of attitude adjustment screws 55. The central axis of the attitude adjustment plate 47 (third central axis O3) may be parallel to the first central axis O1 (see FIG. 2). The third central axis O3 may overlap with the first central axis O1.

[0061] Each of the attitude adjustment screws 55 is threaded into a female thread (not shown) provided in the position adjustment plate 51. Each of the attitude adjustment screws 55 extends along a direction perpendicular to the first central axis O1. Specifically, each of the attitude adjustment screws 55 extends, for example, along the third direction 103. The central axes of the attitude adjustment screws 55 are spaced apart from the third central axis O3. The front end of each of the attitude adjustment screws 55 faces the position adjustment plate 51.

[0062] As each of the plurality of attitude adjustment screws 55 moves, one of the plurality of attitude adjustment screws 55 presses against the attitude adjustment plate 47. This causes the attitude adjustment plate 47 to rotate around the third central axis O3 in the circumferential direction 104. From another perspective, as each of the plurality of attitude adjustment screws 55 moves, the attitude adjustment unit 27 rotates the first electrode wheel 1 (see FIG. 2 ) in the circumferential direction 104 around the first central axis O1. The electrode wheel adjustment unit 23 may rotate the first electrode wheel 1 in the direction opposite to the circumferential direction 104.

[0063] 10 , the attitude adjustment plate 47 has a first protrusion 63 and a second protrusion 64. The first protrusion 63 is fitted into a first recess 59 provided in the position adjustment plate 51. The first protrusion 63 is configured to be slidable relative to the first recess 59. The second protrusion 64 is fitted into a second recess 79 provided in the electrode wheel connection portion 24.

[0064] The electrode wheel adjustment unit 23 has a plurality of second fixing screws 69. Each of the plurality of second fixing screws 69 is screwed into the position adjustment plate 51. The posture adjustment plate 47 is fastened to the position adjustment plate 51 by the plurality of second fixing screws 69. When the posture adjustment unit 27 rotates the first electrode wheel 1, the fastening between the posture adjustment plate 47 and the position adjustment plate 51 is loosened. The electrode wheel connection unit 24 is fastened to the posture adjustment plate 47 by, for example, screws (not shown). The cross section shown in FIG. 10 passes through line X-X shown in FIG. 9.

[0065] As shown in Figure 11, the mash seam welding apparatus 100 has, for example, a first sensor 28 and a second sensor 29. The first sensor 28 is attached, for example, to the second electrode wheel 2. The first sensor 28 detects the position of the workpiece 90. The first sensor 28 is, for example, a reflective photoelectric sensor. In Figure 11, the light emitted by the first sensor 28 is indicated by a two-dot chain line 98. The first sensor 28 detects the presence or absence of an object located on the two-dot chain line 98, for example. In this specification, the two-dot chain line 98 is also referred to as a first detection area 98.

[0066] The second sensor 29 is attached to the second pressure roll 6, for example. The second sensor 29 detects the position of the workpiece 90. The second sensor 29 is, for example, a reflective photoelectric sensor. In FIG. 11 , the light emitted by the second sensor 29 is indicated by a two-dot chain line 99. The second sensor 29 detects the presence or absence of an object located on the two-dot chain line 99, for example. In this specification, the two-dot chain line 99 is also referred to as a second detection area 99.

[0067] 12, the mash seam welding apparatus 100 has a control unit 10. The control unit 10 is electrically connected to a first servo motor 11, a second servo motor 41, a first sensor 28, a second sensor 29, a frame drive unit 50, and a power supply 60. The control unit 10 is configured by, for example, a personal computer and a servo driver.

[0068] The control unit 10 controls and operates the first servo motor 11 by outputting a signal to the first servo motor 11. From another perspective, the control unit 10 moves the first electrode wheel 1 along the first direction 101 by outputting a signal to the first servo motor 11. Specifically, the control unit 10 controls the start of movement of the first electrode wheel 1, the stopping of the first electrode wheel 1, the position of the first electrode wheel 1, the speed of the first electrode wheel 1, and the acceleration of the first electrode wheel 1.

[0069] The control unit 10 receives a signal related to the torque applied to the first servo motor 11 from the first servo motor 11. The control unit 10 receives a signal related to the position of the first electrode wheel 1 in the first direction 101 from the first servo motor 11.

[0070] The control unit 10 controls and operates the second servo motor 41 by outputting a signal to the second servo motor 41. From another perspective, the control unit 10 moves the first pressure roll 5 along the first direction 101 by outputting a signal to the second servo motor 41. Specifically, the control unit 10 controls the start of movement of the first pressure roll 5, the stop of the first pressure roll 5, the position of the first pressure roll 5, the speed of the first pressure roll 5, and the acceleration of the first pressure roll 5.

[0071] The control unit 10 receives a signal related to the torque applied to the second servo motor 41 from the second servo motor 41. The control unit 10 receives a signal related to the position of the second electrode wheel 2 in the first direction 101 from the second servo motor 41.

[0072] The control unit 10 receives signals output from the first sensor 28 and the second sensor 29. The control unit 10 controls the first servo motor 11 based on the signal output from the first sensor 28. The control unit 10 controls the second servo motor 41 based on the signal output from the second sensor 29.

[0073] The control unit 10 controls and operates the frame driving unit 50 by outputting a signal to the frame driving unit 50. From another perspective, the control unit 10 moves the first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6 along a direction parallel to the second direction 102 by outputting a signal to the frame driving unit 50. The control unit 10 supplies a current between the first electrode wheel 1 and the second electrode wheel 2 by outputting a signal to the power source 60.

[0074] <Operation of Mash Seam Welding Apparatus> Next, the operation of the mash seam welding apparatus 100 will be described.

[0075] 13 and 14 , a workpiece 90 is prepared by overlapping a first plate material 91 and a second plate material 92 (step S10). In step S10, the first electrode wheel 1 and the second electrode wheel 2 are spaced apart from each other. The distance between the first electrode wheel 1 and the second electrode wheel 2 in the first direction 101 is greater than the thickness of the workpiece 90 in the first direction 101. Similarly, in step S10, the first pressure roll 5 and the second pressure roll 6 are spaced apart from each other. The distance between the first pressure roll 5 and the second pressure roll 6 in the first direction 101 is greater than the thickness of the workpiece 90 in the first direction 101. The control unit 10 outputs a signal to the power source 60 to supply current to the first electrode wheel 1 and the second electrode wheel 2.

[0076] As shown in Figures 13 and 15, the control unit 10 outputs a signal to the frame drive unit 50 (see Figure 12) to move the carriage frame 9 (see Figure 1) along arrow A1. Specifically, the frame drive unit 50 applies a force to the carriage frame 9, causing each of the multiple support wheels 80 to roll on a floor (not shown). This causes the first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6 to move along arrow A1 (step S20). The direction of arrow A1 is the same as the second direction 102. This causes the workpiece 90 to approach the first detection area 98.

[0077] The control unit 10 determines whether the workpiece 90 has reached the first detection area 98 based on the signal output from the first sensor 28 (step S30). If the control unit 10 determines that the workpiece 90 has not reached the first detection area 98 (NO in step S30), the control unit 10 continues the processing of step S30.

[0078] When the control unit 10 determines that the workpiece 90 has reached the first detection area 98 (YES in step S30), it outputs a signal to the first servo motor 11 to move the first electrode wheel 1 along the arrow A2 (step S40). The direction of the arrow A2 is the same as the first direction 101.

[0079] 16 , the first electrode wheel 1 and the second electrode wheel 2 sandwich the workpiece 90 located between them. This causes a current to flow between the first electrode wheel 1 and the second electrode wheel 2 through the workpiece 90. Heat generated by the current welds the portion of the workpiece 90 located between the first electrode wheel 1 and the second electrode wheel 2. This welds the first plate material 91 and the second plate material 92 together.

[0080] The first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6 continue to move along the arrow A1. Each of the first electrode wheel 1 and the second electrode wheel 2 rotates due to the frictional force received from the workpiece 90. From another perspective, each of the first electrode wheel 1 and the second electrode wheel 2 rolls on the workpiece 90.

[0081] The control unit 10 determines whether the workpiece 90 has reached the second detection area 99 based on the signal output from the second sensor 29 (step S50). If the control unit 10 determines that the workpiece 90 has not reached the second detection area 99 (NO in step S50), the control unit 10 continues the processing of step S50.

[0082] 17 , when the control unit 10 determines that the workpiece 90 has reached the second detection area 99 (YES in step S50), it outputs a signal to the second servo motor 41 to move the first pressure roll 5 along the arrow A3 (step S60). The direction of the arrow A3 is the same as the first direction 101.

[0083] As shown in Fig. 18 , the first pressure roll 5 and the second pressure roll 6 sandwich the workpiece 90 located between them. As shown in Fig. 19 , the first pressure roll 5 and the second pressure roll 6 each rotate due to the frictional force received from the workpiece 90. From another perspective, the first pressure roll 5 and the second pressure roll 6 each roll on the workpiece 90. In this way, the welded workpiece 90 is rolled.

[0084] The first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6 continue to move along the second direction 102 until the workpiece 90 passes through the second detection area 99. In this manner, mash seam welding is performed on the workpiece 90.

[0085] Next, the effects of the mash seam welding apparatus 100 according to the first embodiment will be described.

[0086] Typically, in mash seam welding equipment, a cylinder is used as a pressure device that presses the electrode wheel against the workpiece. When a pneumatic cylinder is used, many parts that make up the pneumatic circuit are required. Similarly, when a hydraulic cylinder is used, many parts that make up the hydraulic circuit are required. Therefore, when a cylinder is used as a pressure device, parts need to be replaced frequently, making the mash seam welding equipment difficult to maintain.

[0087] The mash seam welding apparatus 100 according to the first embodiment includes a first electrode wheel 1, a second electrode wheel 2, and an electrode wheel pressurizing unit 3. The electrode wheel pressurizing unit 3 presses the first electrode wheel 1 against the workpiece 90 in a first direction 101 from the first electrode wheel 1 to the second electrode wheel 2. The electrode wheel pressurizing unit 3 includes a first servo motor 11. This eliminates the need for a cylinder for pressing the first electrode wheel 1 against the workpiece 90. This also eliminates the need for components for a pneumatic or hydraulic circuit. This reduces the number of components in the mash seam welding apparatus 100 compared to when a pneumatic or hydraulic cylinder is used. This reduces the frequency with which components of the mash seam welding apparatus 100 need to be replaced. As a result, the maintainability of the mash seam welding apparatus 100 is improved.

[0088] When the first electrode wheel 1 is pressed against the workpieces 90, the first electrode wheel 1 receives a reaction force from the workpieces 90. Therefore, the mash seam welding apparatus 100 is required to withstand the reaction force received from the workpieces 90.

[0089] 20 , when the first electrode wheel 1 is pressed against the workpiece 90, the first electrode wheel 1 receives a reaction force R1 from the workpiece 90 in a direction opposite to the first direction 101. At the same time, the electrode wheel support portion 15 receives a pressing force P1 from the first feed screw portion 14. The pressing force P1 is a force in the first direction 101 along the first central axis O1. When the first electrode wheel 1 is stationary in the first direction 101, the magnitude of the pressing force P1 is substantially the same as the magnitude of the reaction force R1.

[0090] The electrode wheel guide portion 16 is subjected to a first moment M1 caused by the pressing force P1 and a second moment M2 caused by the reaction force R1. The direction of the first moment M1 is opposite to the direction of the second moment M2. Therefore, the smaller the difference between the magnitudes of the first moment M1 and the second moment M2, the smaller the moment applied to the electrode wheel guide portion 16.

[0091] The distance between the first central axis O1 and the electrode wheel guide portion 16 in a direction perpendicular to the direction of the pressing force P1 is defined as a first distance E1. The distance between the center of the contact surface between the first electrode wheel 1 and the workpiece 90 and the electrode wheel guide portion 16 is defined as a second distance E2. When the magnitude of the pressing force P1 and the magnitude of the reaction force R1 are the same, it is considered that the smaller the difference between the first distance E1 and the second distance E2, the smaller the difference between the magnitude of the first moment M1 and the magnitude of the second moment M2. This is considered to result in a smaller moment applied to the electrode wheel guide portion 16.

[0092] According to the mash seam welding apparatus 100 of the first embodiment, the electrode wheel pressurizing unit 3 includes a first feed screw unit 14, an electrode wheel support unit 15, and an electrode wheel guide unit 16. The electrode wheel support unit 15 connects the first feed screw unit 14 and the first electrode wheel 1. The electrode wheel guide unit 16 is attached to the electrode wheel support unit 15. The central axis (first central axis O1) of the first feed screw unit 14 intersects with the first electrode wheel 1. This reduces the difference between the first distance E1 and the second distance E2. This is believed to reduce the difference between the magnitude of the first moment M1 and the magnitude of the second moment M2. Therefore, the moment applied to the electrode wheel guide unit 16 can be reduced. As a result, the strength of the mash seam welding apparatus 100 against the reaction force applied to the first electrode wheel 1 can be improved.

[0093] According to the mash seam welding apparatus 100 of the first embodiment, the electrode wheel pressurizing unit 3 can use the first servo motor 11 to detect the magnitude of the torque being applied to the first servo motor 11. Therefore, when the first electrode wheel 1 and the second electrode wheel 2 sandwich the workpiece 90, the first servo motor 11 can measure the pressure that the first electrode wheel 1 and the second electrode wheel 2 apply to the workpiece 90. Therefore, by determining whether the torque being applied to the first servo motor 11 is within a predetermined range when the first electrode wheel 1 and the second electrode wheel 2 sandwich the workpiece 90, it is possible to detect the presence or absence of an abnormality when the first electrode wheel 1 and the second electrode wheel 2 press the workpiece 90.

[0094] 21 and 22 , when mash seam welding is performed on the workpiece 90, the workpiece 90 may become welded between the first electrode wheel 1 and the second electrode wheel 2 while the first electrode wheel 1 is pressed against the second electrode wheel 2. In this case, the first electrode wheel 1 rides on the workpiece 90.

[0095] 23 , when the first electrode wheel 1 climbs onto the workpiece 90, the first electrode wheel 1 receives a reaction force (climbing reaction force R2) from the workpiece 90. The magnitude of the climbing reaction force R2 is greater than the magnitude of the reaction force R1 (see FIG. 20 ) received by the first electrode wheel 1 when the first electrode wheel 1 and the second electrode wheel 2 sandwich the workpiece 90. Furthermore, the climbing reaction force R2 includes a component force B1 parallel to the first direction 101 and a component force B2 parallel to the second direction 102. Therefore, when the first electrode wheel 1 climbs onto the workpiece 90, the strength required of the mash seam welding apparatus 100 increases compared to when the first electrode wheel 1 does not climb onto the workpiece 90.

[0096] According to the mash seam welding apparatus 100 of embodiment 1, the control unit 10 controls the first servo motor 11 so that the first electrode wheel 1 and the second electrode wheel 2, which are spaced apart from each other, sandwich the workpiece 90 between them. Therefore, when welding the workpiece 90, the first electrode wheel 1 does not climb onto the workpiece 90. This prevents the application of the climbing reaction force R2 to the first electrode wheel 1. This reduces the strength required for the mash seam welding apparatus 100. This allows the mash seam welding apparatus 100 to be made lighter and more compact.

[0097] According to the mash seam welding apparatus 100 of the first embodiment, the electrode wheel guide portion 16 includes a first rail 31 and a second rail 32. The first rail 31 and the second rail 32 are aligned along a direction (second direction 102) perpendicular to both the first direction 101 and the rotation axis (first rotation axis C1) of the first electrode wheel 1. This improves the strength of the electrode wheel guide portion 16 against forces parallel to the second direction 102, such as frictional forces generated between the workpiece 90 and the first electrode wheel 1. This allows the size of the blocks attached to the rail or the pitch between multiple blocks to be reduced compared to when the electrode wheel guide portion 16 has only one rail. This allows the size of the electrode wheel guide portion 16 in the first direction 101 to be reduced while maintaining the strength of the electrode wheel guide portion 16.

[0098] According to the mash seam welding apparatus 100 of the first embodiment, the electrode wheel support unit 15 includes a position adjustment unit 26 and an attitude adjustment unit 27. By moving each of the first position adjustment screw 56, the second position adjustment screw 57, and the third position adjustment screw 58, the position adjustment unit 26 moves the first electrode wheel 1 along an in-plane direction perpendicular to the first central axis O1. By moving each of the multiple attitude adjustment screws 55, the attitude adjustment unit 27 rotates the first electrode wheel 1 along the circumferential direction 104. Therefore, by rotating the screws, the position and attitude of the first electrode wheel 1 can be easily adjusted. This eliminates the need for work that places a heavy burden on the operator, such as adjustment using a hammer. As a result, the burden on the operator can be reduced.

[0099] Modification of First Embodiment As shown in Fig. 24, the mash seam welding apparatus 100 may have a third sensor 38 and a fourth sensor 39. Each of the first sensor 28, the second sensor 29, the third sensor 38, and the fourth sensor 39 may be an optical displacement sensor. The first sensor 28, the second sensor 29, the third sensor 38, and the fourth sensor 39 input signals related to the distances from the first sensor 28, the second sensor 29, the third sensor 38, and the fourth sensor 39 to the workpiece 90 to the control unit 10 (see Fig. 12).

[0100] The third sensor 38 faces the first sensor 28. The third sensor 38 is attached to a fixed frame 70. The fourth sensor 39 faces the second sensor 29. The fourth sensor 39 is attached to the fixed frame 70.

[0101] The control unit 10 (see FIG. 12 ) can calculate the thickness of the workpiece 90 in the first direction 101 based on a signal related to the distance from the first sensor 28 to the workpiece 90 and a signal related to the distance from the third sensor 38 to the workpiece 90. Based on the calculated thickness, the control unit 10 controls the first servo motor 11 so that the pressure applied to the workpiece 90 by the first electrode wheel 1 and the second electrode wheel 2 becomes a predetermined magnitude.

[0102] Similarly, the control unit 10 can calculate the thickness of the workpiece 90 in the first direction 101 based on a signal relating to the distance from the second sensor 29 to the workpiece 90 and a signal relating to the distance from the fourth sensor 39 to the workpiece 90. Based on the calculated thickness, the control unit 10 controls the second servo motor 41 so that the pressure applied to the workpiece 90 by the first pressure roll 5 and the second pressure roll 6 becomes a predetermined magnitude.

[0103] According to the mash seam welding apparatus 100 relating to a modified example of embodiment 1, even if there is variation in the thickness of the workpieces 90 among multiple workpieces 90, the variation in the pressure applied to the workpieces 90 can be reduced.

[0104] It should be noted that the mash seam welding apparatus 100 does not necessarily have to include the first sensor 28, the second sensor 29, the third sensor 38, and the fourth sensor 39. From another perspective, the above-described steps S30 and S50 (see FIG. 13 ) do not necessarily have to be performed in welding the workpiece 90. If steps S30 and S50 are not performed, the control unit 10 measures the elapsed time from the point in time when the frame drive unit 50 starts to move the first electrode wheel 1, the second electrode wheel 2, the first pressure roll 5, and the second pressure roll 6. Based on the elapsed time, the control unit 10 determines whether to perform steps S40 and S60.

[0105] Although the above describes a configuration in which the second electrode wheel 2 does not move in a direction parallel to the first direction 101, the second electrode wheel 2 may be movable in a direction parallel to the first direction 101. Specifically, the mash seam welding apparatus 100 may have a pressure unit that presses the second electrode wheel 2 against the workpiece 90 in the direction opposite to the first direction 101. The configuration of this pressure unit is similar to the configuration of the electrode wheel pressure unit 3. Similarly, the mash seam welding apparatus 100 may have a pressure unit that presses the second pressure roll 6 against the workpiece 90 in the direction opposite to the first direction 101. The configuration of this pressure unit is similar to the configuration of the roll pressure unit 7.

[0106] Embodiment 2 Next, the configuration of a mash seam welding apparatus 100 according to Embodiment 2 will be described. The mash seam welding apparatus 100 according to Embodiment 2 differs from the mash seam welding apparatus 100 according to Embodiment 1 mainly in the configuration of the fixed frame 70, but is otherwise substantially identical to the mash seam welding apparatus 100 according to Embodiment 1. The following description will focus on the differences from the mash seam welding apparatus 100 according to Embodiment 1.

[0107] 25 , a first opening 93 is provided in a portion of the fixed frame 70 facing the first lead screw unit 14. Specifically, the first opening 93 is provided in the second side wall portion 72. The first opening 93 is connected to the first space 88 (see FIG. 2 ). When viewed perpendicularly to the first central axis O1, the first lead screw unit 14 is located within the first opening 93.

[0108] A second opening 94 is provided in a portion of the fixed frame 70 facing the second lead screw portion 44. Specifically, the second opening 94 is provided in the second side wall portion 72. The second opening 94 is connected to the second space 89 (see FIG. 2). When viewed perpendicularly to the second central axis O2, the second lead screw portion 44 is located within the second opening 94.

[0109] 25 , the length of the second side wall portion 72 in the first direction 101 may be shorter than the lengths of the third side wall portion 73 and the fourth side wall portion 74. As shown in FIG. 26 , the length of the second side wall portion 72 in the first direction 101 may be shorter than the length of the first side wall portion 71.

[0110] According to the mash seam welding apparatus 100 of the second embodiment, the fixed frame 70 surrounds the first feed screw portion 14. The first opening 93 is provided in the fixed frame 70. This makes it possible to reduce the weight of the fixed frame 70 while preventing a decrease in the rigidity of the fixed frame 70. This allows the weight of the mash seam welding apparatus 100 to be reduced.

[0111] According to the mash seam welding device 100 of the second embodiment, a first opening 93 is provided in a portion of the fixed frame 70 facing the first lead screw portion 14. This allows maintenance of the first lead screw portion 14 via the first opening 93. Specifically, for example, it is possible to supply grease to each of the first screw shaft 18 and the first nut portion 19 via the first opening 93. This improves the ease of maintenance of the first lead screw portion 14.

[0112] Modification of Embodiment 2 As shown in FIG. 27 , the fixed frame 70 may have a first lid 86 and a second lid 87. The first lid 86 is attached to the second side wall portion 72. The first lid 86 closes the first opening 93 (see FIG. 25 ). The first lid 86 is detachable from the second side wall portion 72. The second lid 87 is attached to the second side wall portion 72. The second lid 87 closes the second opening 94 (see FIG. 25 ). The second lid 87 is detachable from the second side wall portion 72.

[0113] Attaching the first lid 86 to the first opening 93 can prevent foreign matter from entering the first feed screw portion 14. Similarly, attaching the second lid 87 to the second opening 94 can prevent foreign matter from entering the second feed screw portion 44.

[0114] As shown in Figure 28, the shape of the fourth side wall portion 74 may be trapezoidal. Specifically, as viewed in the second direction 102, the oblique side 81 of the fourth side wall portion 74 is provided so as to extend along an imaginary straight line 110 that connects the lower end surfaces of the first side wall portion 71 and the second side wall portion 72 in the shortest distance. The shapes of the third side wall portion 73 and the intermediate wall portion 75 (see Figure 27) are substantially the same as the shape of the fourth side wall portion 74. As viewed in the second direction 102, the fourth side wall portion 74 overlaps with the third side wall portion 73 and the intermediate wall portion 75.

[0115] The trapezoidal shape of the fourth side wall portion 74 effectively reduces the weight of the fixed frame 70 while preventing a decrease in the rigidity of the fixed frame 70. The shapes of the third side wall portion 73 and the intermediate wall portion 75 are substantially the same as the shape of the fourth side wall portion 74.

[0116] Embodiment 3 Next, the configuration of a mash seam welding apparatus 100 according to Embodiment 3 will be described. The mash seam welding apparatus 100 according to Embodiment 3 differs from the mash seam welding apparatus 100 according to Embodiment 1 mainly in that it has a third servo motor 120 that rotates the first electrode wheel 1, but in other respects is substantially the same as the mash seam welding apparatus 100 according to Embodiment 1. The following description will focus on the differences from the mash seam welding apparatus 100 according to Embodiment 1.

[0117] As shown in Fig. 29, the electrode wheel support unit 15 (see Fig. 3) has an electrode head 130, a third servo motor 120, a third reducer 121, a first gear 122, a second gear 123, and a shaft cover 135. The electrode head 130 is connected to, for example, the electrode wheel connection unit 24 (see Fig. 3). From another perspective, the electrode wheel connection unit 24 connects the electrode head 130 and the electrode wheel adjustment unit 23. Note that the electrode head 130 may be connected to the electrode wheel adjustment unit 23 (see Fig. 3).

[0118] The third servo motor 120 and the third reducer 121 are each attached to the electrode head 130. The third servo motor 120 rotates the first electrode wheel 1. The third reducer 121 is attached to the third servo motor 120.

[0119] The first gear 122 transmits the rotation of the third servo motor 120 to the second gear 123. The second gear 123 is in contact with the first gear 122. The first gear 122 and the second gear 123 are aligned along a direction perpendicular to the first rotation axis C1. The second gear 123 is fixed to the first electrode wheel 1. The second gear 123 rotates integrally with the first electrode wheel 1. The central axis of the second gear 123 may overlap with the first rotation axis C1.

[0120] As shown in FIG. 30 , the control unit 10 is electrically connected to the third servo motor 120. The control unit 10 controls and operates the third servo motor 120 by outputting a signal to the third servo motor 120. From another perspective, the control unit 10 rotates the first electrode wheel 1 by outputting a signal to the third servo motor 120. The control unit 10 controls the start and stop of rotation of the first electrode wheel 1, the rotation speed of the first electrode wheel 1, and the angular velocity of the first electrode wheel 1. A signal related to the torque applied to the third servo motor 120 is input to the control unit 10 from the third servo motor 120. The first servo motor 11 is an example of a position detection unit disclosed herein. The first servo motor 11 detects the position of the first electrode wheel 1 in the first direction 101.

[0121] The control unit 10 has a memory unit 20. The memory unit 20 stores, for example, the position of the first electrode wheel 1 detected by the first servo motor 11 and the set value of the rotation speed of the third servo motor 120. When welding the workpiece 90, the control unit 10 reads the set value of the rotation speed of the third servo motor 120 from the memory unit 20 and rotates the third servo motor 120 so that the rotation speed of the third servo motor becomes the set value. As a result, the first electrode wheel 1 rotates while welding the workpiece 90.

[0122] Next, the operation of adjusting the rotation speed of the third servo motor 120 will be described with reference to Figure 31. For example, the operation of adjusting the rotation speed starts when welding of the workpiece 90 is started. Specifically, for example, the operation of adjusting the rotation speed starts when step S40 shown in Figure 13 is started.

[0123] 31 , the control unit 10 acquires the lowered position of the first electrode wheel 1 (step S70). Specifically, the control unit 10 determines whether the first electrode wheel 1 and the workpiece 90 have come into contact with each other based on a signal output from the first servo motor 11 related to the torque applied to the first servo motor 11. When the control unit 10 determines that the first electrode wheel 1 and the workpiece 90 have come into contact with each other, the control unit 10 acquires information related to the position of the first electrode wheel 1 from the first servo motor 11. In this way, the control unit 10 acquires the position of the first electrode wheel 1 in a state in which the first electrode wheel 1 is in contact with the workpiece 90. The control unit 10 outputs the acquired lowered position of the first electrode wheel 1 to the memory unit 20 for storage.

[0124] The control unit 10 may acquire the lowered position of the first electrode wheel 1 before the workpiece 90 is welded by the first electrode wheel 1 and the second electrode wheel 2, or may acquire the lowered position of the first electrode wheel 1 after the workpiece 90 has been welded.

[0125] Next, the control unit 10 determines whether the lowered position of the first electrode wheel 1 has changed since the previous welding (step S80). Specifically, the control unit 10 reads the lowered position of the first electrode wheel 1 during the previous welding from the memory unit 20. If the lowered position of the first electrode wheel 1 acquired in step S70 is the same as the lowered position of the first electrode wheel 1 during the previous welding (NO in step S80), the control unit 10 ends the operation of adjusting the rotation speed.

[0126] If the lowered position of the first electrode wheel 1 acquired in step S70 is different from the lowered position of the first electrode wheel 1 during the previous welding (YES in step S80), the control unit 10 calculates the required number of rotations of the third servo motor 120 (step S90). Specifically, the control unit 10 first calculates the amount of change between the lowered position of the first electrode wheel 1 during the previous welding and the lowered position of the first electrode wheel 1 acquired in step S70. This amount of change can be considered to be the amount of wear of the first electrode wheel 1. The amount of wear of the first electrode wheel 1 can be considered to be the amount of change in the radius of the first electrode wheel 1.

[0127] The control unit 10 calculates the required rotation speed of the third servo motor 120 so that the peripheral speed of the outer peripheral surface (first outer peripheral surface 33) of the first electrode wheel 1 becomes equal to a predetermined target value. When the peripheral speed of the first outer peripheral surface 33 is V (m / s) and the rotation speed of the first electrode wheel 1 is N (rpm), V = π [rad] × N / 60 holds. The control unit 10 calculates the required rotation speed of the third servo motor 120, for example, based on the above formula. The control unit 10 inputs and stores the calculated required rotation speed into the memory unit 20 as the set value for the rotation speed of the third servo motor 120. As a result, in subsequent welding operations, the control unit 10 controls the third servo motor 120 so that the rotation speed of the third servo motor 120 becomes the rotation speed calculated in step S90. As described above, the control unit 10 controls the rotation speed of the third servo motor 120 based on the position of the first electrode wheel 1 in contact with the workpiece 90, as detected by the first servo motor 11.

[0128] In step S80, the control unit 10 may determine that the lowered position of the first electrode wheel 1 has changed if the amount of change between the lowered position of the first electrode wheel 1 during the previous welding and the lowered position of the first electrode wheel 1 obtained in step S70 is greater than or equal to a predetermined threshold value.

[0129] Next, the operation and effect of the mash seam welding apparatus 100 according to the third embodiment will be described.

[0130] FIG. 32 shows two first electrode wheels 1. The first electrode wheel 1 on the right has worn first outer peripheral surface 33. On the other hand, the first electrode wheel 1 on the left is not worn. As shown in FIG. 31 , the first electrode wheel 1 may be worn when mash seam welding is repeated. When comparing a worn first electrode wheel 1 with an unworn first electrode wheel 1, the positions of the first rotation axes C1 when in contact with the workpiece 90 are different. Assuming that the first outer peripheral surface 33 is worn evenly over the entire circumference, the distance in the first direction 101 between the first rotation axis C1 of the worn first electrode wheel 1 and the first rotation axis C1 of the unworn first electrode wheel 1 (third distance E3) is the same as the wear amount W of the first electrode wheel 1 in the radial direction.

[0131] When the first electrode wheel 1 is worn, the diameter of the first electrode wheel 1 becomes smaller. Therefore, if the rotation speed of the first electrode wheel 1 remains the same, the wear of the first electrode wheel 1 causes the circumferential speed of the first outer peripheral surface 33 to slow down. In FIG. 32 , the size of the arrow V corresponds to the circumferential speed of the first outer peripheral surface 33. When the circumferential speed of the first outer peripheral surface 33 changes excessively, the difference between the circumferential speed of the first outer peripheral surface 33 and the feed speed of the workpiece 90 becomes large. In this case, the welding quality deteriorates.

[0132] In the mash seam welding apparatus 100 according to the third embodiment, the control unit 10 controls the rotation speed of the third servo motor 120 based on the position of the first electrode wheel 1 when in contact with the workpiece 90. Therefore, even when the first electrode wheel 1 is worn, it is possible to prevent the circumferential speed of the outer circumferential surface of the first electrode wheel 1 from changing. Therefore, it is possible to prevent the relationship between the feed speed of the workpiece 90 and the circumferential speed of the outer circumferential surface of the first electrode wheel 1 from changing. This makes it possible to stabilize the welding quality.

[0133] Although the configuration of the first electrode wheel 1 has been described above, the configuration of the second electrode wheel 2 may be the same as the configuration of the first electrode wheel 1. Specifically, the electrode wheel support base 4 (see FIG. 1 ) may have a fourth servo motor that rotates the second electrode wheel 2. The control unit 10 may control the rotation speed of the fourth servo motor based on the position of the second electrode wheel 2 in a state in which it is in contact with the workpiece 90.

[0134] In the above, the first servo motor 11 serves as the position detector. However, the mash seam welding device 100 may have a sensor such as a photosensor as the position detector.

[0135] Embodiment 4 Next, the configuration of a mash seam welding apparatus 100 according to Embodiment 4 will be described. The mash seam welding apparatus 100 according to Embodiment 4 differs from the mash seam welding apparatus 100 according to Embodiment 1 mainly in the configuration of the portion that supports the first electrode wheel 1, but is otherwise substantially identical to the mash seam welding apparatus 100 according to Embodiment 1. The following description will focus on the differences from the mash seam welding apparatus 100 according to Embodiment 1.

[0136] As shown in Fig. 33, the electrode wheel support part 15 (see Fig. 3) has a shaft part 134, an electrode head 130, a base part 131, and a shaft cover 135. The shaft part 134 supports the first electrode wheel 1. The first electrode wheel 1 is attached to the shaft part 134. The shaft part 134 extends along the first rotation axis C1. The shaft part 134 is made of copper or a copper alloy.

[0137] The electrode head 130 supports a shaft 134. Specifically, the electrode head 130 has a first bearing 136 and a second bearing 137. The first bearing 136 and the second bearing 137 each support the shaft 134. When the first electrode wheel 1 receives a reaction force R1 from the workpiece 90, a third moment M3 is applied to the shaft 134. Furthermore, due to the third moment M3, a force F is applied from the shaft 134 to the electrode head 130. The electrode head 130 has the first bearing 136 and the second bearing 137, which improves the rigidity of the electrode head 130 against the force F. Therefore, tilting of the shaft 134 due to the reaction force R1 can be prevented.

[0138] The electrode head 130 is fastened to the base 131 by screws (not shown). The electrode head 130 is made of an iron-based material such as rolled steel, carbon steel, or stainless steel. The specific gravity of an iron-based material is smaller than that of copper-based materials such as copper and copper alloys. Therefore, compared to when the electrode head 130 is made of a copper-based material, the weight of the electrode head 130 can be reduced by making the electrode head 130 of an iron-based material. This allows the weight of the mash seam welding apparatus 100 to be reduced. Note that the material making up the electrode head 130 is not limited to an iron-based material. The electrode head 130 may be made of a material that is lighter and more rigid than a copper-based material, such as a titanium-based material.

[0139] The shaft cover 135 covers the end of the shaft portion 134 opposite the end of the shaft portion 134 attached to the first electrode wheel 1. The shaft cover 135 protects the end of the shaft portion 134. The shaft cover 135 is attached to the electrode head 130.

[0140] The base 131 is connected to, for example, the electrode wheel connection part 24 (see FIG. 3). From another perspective, the electrode wheel connection part 24 connects the base 131 to the electrode wheel adjustment part 23 (see FIG. 3). The electrode head 130 may be connected to the electrode wheel adjustment part 23. The base 131 is made of a metal having high conductivity, such as copper or a copper alloy. The base 131 may also be made of an aluminum alloy having sufficient conductivity.

[0141] The electrode head 130 has a third opening 144 as an engaging portion. The third opening 144 opens in the direction opposite to the first direction 101. The base 131 has a third protrusion 146 as an engaged portion. The third protrusion 146 corresponds to the third opening 144. The third protrusion 146 and the third opening 144 are engaged with each other. Specifically, the third protrusion 146 is inserted into the third opening 144.

[0142] The engagement between the third opening 144 and the third protrusion 146 limits movement of the electrode head 130 in a direction parallel to the third direction 103. Specifically, the lengths of the third opening 144 and the third protrusion 146 in the third direction 103 are determined so that the third opening 144 and the third protrusion 146 fit together. This makes it easy to position the electrode head 130 and the first electrode wheel 1 relative to the base 131 in the third direction 103. Note that the electrode head 130 may have a protrusion as the engaging portion, and the base 131 may have a recess or an opening as the engaged portion.

[0143] The base 131 has a contact surface 145 that is in contact with the top surface of the electrode head 130. The top surface of the electrode head 130 and the contact surface 145 are parallel to each other. The contact surface 145 is perpendicular to the side surface of the third protrusion 146.

[0144] 34 , the electrode wheel support part 15 (see FIG. 3 ) has a first contactor 132, two second contactors 133, a third fixing screw 138, a fourth fixing screw 139, and a nut 140. The first contactor 132 is located between the shaft part 134 and the base part 131. The first contactor 132 is fastened to a third convex part 146 of the base part 131 by the third fixing screw 138. The first contactor 132 extends along the third direction 103.

[0145] The shaft portion 134 and the first contactor 132 are located between the two second contactors 133. In the second direction 102, the width of the first contactor 132 is shorter than the width of the third protrusion 146. The two second contactors 133 sandwich the shaft portion 134. By tightening the fourth fixing screw 139 and the nut 140 together, the two second contactors 133 are fixed so that the shaft portion 134 is sandwiched between them.

[0146] Since the second contactor 133 and the first contactor 132 attached to the base 131 are separate bodies, the first contactor 132 can be attached to the base 131 outside the electrode head 130. This improves the ease of assembly of the mash seam welding device 100.

[0147] The two second contactors 133 sandwich the first contactor 132. This reduces the inclination of the extension direction of the shaft 134 relative to the extension direction of the first contactor 132. Therefore, when attaching the first contactor 132 to the base 131, the orientation of the shaft 134 can be indirectly adjusted by adjusting the orientation of the first contactor 132. This makes it easy to adjust the orientation of the shaft 134.

[0148] According to the mash seam welding apparatus 100 of the fourth embodiment, the shaft 134 supports the first electrode wheel 1. The electrode head 130 supports the shaft 134. The electrode head 130 has a third opening 144 as an engaging portion. The base 131 has a third convex portion 146 as an engaged portion. The third convex portion 146 engages with the third opening 144. This limits the movement of the electrode head 130 relative to the base 131. Therefore, when assembling the mash seam welding apparatus 100, the electrode head 130, the shaft 134, and the first electrode wheel 1 can be easily positioned relative to the base 131.

[0149] Note that positioning pins, recesses, or contact surfaces may be provided on the first contactor 132 and the base 131. This can prevent the first contactor 132 from being misaligned with respect to the base 131.

[0150] The above-described embodiments can be combined as appropriate. The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0151] Various aspects of the present disclosure are summarized below as appendices. (Supplementary Note 1) A mash seam welding device that welds overlapping workpieces by sandwiching the workpieces between a first electrode wheel and a second electrode wheel and supplying a current between the first electrode wheel and the second electrode wheel, the mash seam welding device comprising: the first electrode wheel; the second electrode wheel facing the first electrode wheel; and an electrode wheel pressure unit that presses the first electrode wheel against the workpieces along a first direction from the first electrode wheel to the second electrode wheel, wherein the electrode wheel pressure unit has: a first servo motor; a first feed screw unit that converts rotation of the first servo motor into linear motion along the first direction; an electrode wheel support unit that connects the first feed screw unit and the first electrode wheel; and an electrode wheel guide unit that is attached to the electrode wheel support unit and guides the electrode wheel support unit and the first electrode wheel along the first direction, wherein a central axis of the first feed screw unit intersects with the first electrode wheel. (Supplementary Note 2) The mash seam welding device according to Supplementary Note 1, further comprising: a first pressure roll; a second pressure roll positioned in the first direction relative to the first pressure roll; and a roll pressure unit that presses the first pressure roll against the workpiece along the first direction, wherein the roll pressure unit has: a second servo motor; a second feed screw unit that converts rotation of the second servo motor into linear motion along the first direction, a roll support unit that connects the second feed screw unit and the first pressure roll, and a roll guide unit that guides the roll support unit and the first pressure roll along the first direction, wherein a central axis of the second feed screw unit intersects with the first pressure roll. (Supplementary Note 3) The mash seam welding device according to Supplementary Note 1 or Supplementary Note 2, further comprising: a control unit that controls the first servo motor, wherein the control unit controls the first servo motor so that the first electrode wheel and the second electrode wheel sandwich the workpiece from a state in which the first electrode wheel and the second electrode wheel are spaced apart from each other.(Supplementary Note 4) The mash seam welding device according to Supplementary Note 3, further comprising a sensor that detects a position of the workpiece, and the control unit controls the first servo motor based on a signal output from the sensor so that the first electrode wheel and the second electrode wheel sandwich the workpiece between them from a state in which the first electrode wheel and the second electrode wheel are spaced apart. (Supplementary Note 5) The mash seam welding device according to any one of Supplementary Notes 1 to 4, further comprising a fixing frame to which the electrode wheel guide unit is attached and which surrounds the first feed screw unit, and an opening is provided in a portion of the fixing frame that faces the first feed screw unit. (Supplementary Note 6) The mash seam welding device according to any one of Supplementary Notes 1 to 5, wherein the electrode wheel support section has: a position adjustment section having a plurality of position adjustment screws; and an attitude adjustment section having a plurality of attitude adjustment screws, wherein movement of each of the plurality of position adjustment screws causes the position adjustment section to move the first electrode wheel along an in-plane direction perpendicular to the central axis of the first feed screw section, and movement of each of the plurality of attitude adjustment screws causes the attitude adjustment section to rotate the first electrode wheel along a circumferential direction about the central axis of the first feed screw section. (Supplementary Note 7) The mash seam welding device according to any one of Supplementary Notes 1 to 6, wherein the electrode wheel guide section has a first rail and a second rail spaced apart from the first rail, wherein each of the first rail and the second rail extends along the first direction, and wherein the first rail and the second rail are aligned along a direction perpendicular to each of the first direction and the rotation axis of the first electrode wheel. (Supplementary Note 8) The mash seam welding device according to any one of Supplementary Note 1 or Supplementary Note 7, further comprising: a third servo motor that rotates the first electrode wheel; a control unit that controls the third servo motor; and a position detection unit that detects the position of the first electrode wheel in the first direction, wherein the control unit controls the rotation speed of the third servo motor based on the position of the first electrode wheel in contact with the workpiece detected by the position detection unit.(Supplementary Note 9) The mash seam welding device according to any one of Supplementary Notes 1 to 8, wherein the electrode wheel support portion has: a shaft portion that supports the first electrode wheel and extends along a rotation axis of the first electrode wheel; an electrode head that supports the shaft portion; and a base portion to which the electrode head is attached; the electrode head has an engaging portion; and the base portion has an engaged portion that engages with the engaging portion.

[0152] 1 First electrode wheel, 2 Second electrode wheel, 3 Electrode wheel pressure unit, 4 Electrode wheel support base, 5 First pressure roll, 6 Second pressure roll, 7 Roll pressure unit, 8 Roll support base, 9 Carriage frame, 10 Control unit, 11 First servo motor (position detection unit), 12 First reducer, 13 First coupling, 14 First feed screw unit, 15 Electrode wheel support unit, 16 Electrode wheel guide unit, 18 First screw shaft, 19 First nut unit, 21 Main body unit, 22 First movable frame, 23 Electrode wheel adjustment unit, 24 Electrode wheel connection unit, 25 Screw support unit, 26 Position adjustment unit, 27 Attitude adjustment unit, 28 First sensor, 29 Second sensor, 31 First rail, 32 Second rail, 33 First outer peripheral surface, 34 Second outer peripheral surface, 36 First block, 37 Second block, 38 Third sensor, 39 Fourth sensor, 41 Second servo motor, 42 Second reducer, 43 Second coupling, 44 Second feed screw portion, 45 Roll support portion, 46 Roll guide portion, 47 Attitude adjustment plate, 48 Second screw shaft, 49 Second nut portion, 50 Frame drive portion, 51 Position adjustment plate, 52 Second movable frame, 53 Roll adjustment portion, 54 Roll connection portion, 55 Attitude adjustment screw, 56 First position adjustment screw, 57 Second position adjustment screw, 58 Third position adjustment screw, 59 First recess, 60 Power supply, 61 Third rail, 62 Fourth rail, 63 First convex portion, 64 Second convex portion, 65 Slot, 66 Third block, 67 Fourth block, 68 First fixing screw, 69 Second fixing screw, 70 Fixing frame, 71 First side wall portion, 72 Second side wall portion, 73 Third side wall portion, 74 Fourth side wall portion, 75 Intermediate wall portion, 76 Top plate, 77 Nut, 78 Outer peripheral wall portion, 79 Second recessed portion, 80 Support wheel, 81 Oblique side, 83 First through hole, 84 Second through hole, 85 Bottom portion, 86 First lid, 87 Second lid, 88 First space, 89 Second space, 90 Workpiece, 91 First plate material, 92 Second plate material, 93 First opening, 94 Second opening, 95 Upper frame portion, 96 Lower frame portion, 97 Connection portion, 98 First detection area, 99 Second detection area, 100 Mash seam welding device, 101 First direction, 102 Second direction, 103 Third direction, 104 Circumferential direction, 110 Virtual straight line, 120 Third servo motor, 121 Third reducer, 122 First gear, 123 Second gear, 130 Electrode head, 131 Base portion, 132 First contactor133 Second contactor, 134 Shaft portion, 135 Shaft cover, 136 First bearing, 137 Second bearing, 138 Third fixing screw, 139 Fourth fixing screw, 144 Third opening, 145 Contact surface, 146 Third convex portion, A1, A2, A3 Arrows, B1, B2 Force components, C1 First rotation axis, C2 Second rotation axis, E1 First distance, E2 Second distance, E3 Third distance, F Force, M1 First moment, M2 Second moment, M3 Third moment, O1 First central axis, O2 Second central axis, O3 Third central axis, P1 Pressing force, R1 Reaction force, R2 Riding reaction force, W Wear amount.

Claims

1. A mash seam welding device that welds overlapping workpieces by sandwiching the workpieces between a first electrode wheel and a second electrode wheel and supplying current between the first electrode wheel and the second electrode wheel, the mash seam welding device comprising: the first electrode wheel; the second electrode wheel opposing the first electrode wheel; and an electrode wheel pressure unit that presses the first electrode wheel against the workpieces along a first direction from the first electrode wheel to the second electrode wheel, the electrode wheel pressure unit having: a first servo motor; a first feed screw unit that converts rotation of the first servo motor into linear motion along the first direction; an electrode wheel support unit that connects the first feed screw unit and the first electrode wheel; and an electrode wheel guide unit that is attached to the electrode wheel support unit and guides the electrode wheel support unit and the first electrode wheel along the first direction, the central axis of the first feed screw unit intersects with the first electrode wheel.

2. A mash seam welding device as described in claim 1, further comprising: a first pressure roll; a second pressure roll positioned in the first direction relative to the first pressure roll; and a roll pressure unit that presses the first pressure roll against the workpiece along the first direction, wherein the roll pressure unit has: a second servo motor; a second feed screw unit that converts rotation of the second servo motor into linear motion along the first direction; a roll support unit that connects the second feed screw unit and the first pressure roll; and a roll guide unit that guides the roll support unit and the first pressure roll along the first direction, and wherein the central axis of the second feed screw unit intersects with the first pressure roll.

3. A mash seam welding device as described in claim 1 or claim 2, further comprising a control unit that controls the first servo motor, wherein the control unit controls the first servo motor so that the first electrode wheel and the second electrode wheel sandwich the workpiece from a state in which the first electrode wheel and the second electrode wheel are spaced apart from each other.

4. A mash seam welding device as described in claim 3, further comprising a sensor that detects the position of the workpiece, and wherein the control unit controls the first servo motor based on a signal output from the sensor so that the first electrode wheel and the second electrode wheel sandwich the workpiece from a state in which the first electrode wheel and the second electrode wheel are spaced apart.

5. A mash seam welding device according to any one of claims 1 to 4, further comprising a fixed frame to which the electrode wheel guide portion is attached and which surrounds the first feed screw portion, and an opening is provided in a portion of the fixed frame which faces the first feed screw portion.

6. A mash seam welding device according to any one of claims 1 to 5, wherein the electrode wheel support section has: a position adjustment section having a plurality of position adjustment screws; and an attitude adjustment section having a plurality of attitude adjustment screws, wherein the position adjustment section moves the first electrode wheel along an in-plane direction perpendicular to the central axis of the first feed screw section by movement of each of the plurality of position adjustment screws, and the attitude adjustment section rotates the first electrode wheel in a circumferential direction around the central axis of the first feed screw section by movement of each of the plurality of attitude adjustment screws.

7. A mash seam welding device according to any one of claims 1 to 6, wherein the electrode wheel guide section has a first rail and a second rail spaced apart from the first rail, the first rail and the second rail each extending along the first direction, and the first rail and the second rail aligned along a direction perpendicular to both the first direction and the rotation axis of the first electrode wheel.

8. A mash seam welding device as described in claim 1 or claim 2, further comprising: a third servo motor that rotates the first electrode wheel; a control unit that controls the third servo motor; and a position detection unit that detects the position of the first electrode wheel in the first direction, wherein the control unit controls the rotation speed of the third servo motor based on the position of the first electrode wheel in contact with the workpiece detected by the position detection unit.

9. A mash seam welding device according to any one of claims 1 to 8, wherein the electrode wheel support portion has: a shaft portion that supports the first electrode wheel and extends along the rotation axis of the first electrode wheel; an electrode head that supports the shaft portion; and a base portion to which the electrode head is attached, the electrode head having an engaging portion, and the base portion having an engaged portion that engages with the engaging portion.

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