Welding device and welding method

Abstract

[Problem] To appropriately weld a plurality of members to each other.　[Solution] Provided is a welding device for welding a plurality of members to each other, the welding device comprising: a welding torch; an information acquisition unit capable of acquiring information on a region where the plurality of members viewed from the welding torch side are positioned; and a control unit for controlling welding with the welding torch. The control unit has a start position determination part for determining a start position of the welding with the welding torch. The start position determination part identifies the center of gravity of the region where the plurality of members are positioned from contour information of the region where the plurality of members are positioned, and determines the start position by using the identified center of gravity.　

Description

Welding equipment and welding method

[0001] The present invention relates to a welding device and a welding method.

[0002] Patent Document 1 discloses a technology in which point cloud data of a welding reference surface is acquired using a 3D camera, and a welding torch is positioned opposite a welding position determined based on the acquired point cloud data to perform welding.

[0003] JP 2023-87928 A

[0004] Determining the welding position affects the welding quality. In the case of Patent Document 1, the welding position is determined by acquiring point cloud data. Therefore, processing of the information acquired by the 3D camera and processing of the information required to determine the welding position are complicated.

[0005] When joining a plurality of members together by welding, it is required to be able to more easily determine welding positions and perform welding appropriately.

[0006] One aspect of the present invention is a welding apparatus for welding multiple components together, comprising: a welding torch; an information acquisition unit capable of acquiring information on an area in which the multiple components are located as viewed from the welding torch; and a control unit for controlling welding by the welding torch, wherein the control unit has a start position determination unit that determines a start position for welding by the welding torch, and the start position determination unit identifies the center of gravity of the area in which the multiple components are located from contour information of the area in which the multiple components are located, and determines the start position using the identified center of gravity.

[0007] One aspect of the present invention is a welding method for welding multiple components together using a welding torch, comprising the steps of: acquiring information about the area in which the multiple components are located as seen from the welding torch; determining a start position for welding from contour information about the area in which the multiple components are located; and moving the welding torch to the start position to weld the multiple components together, wherein the step of determining the start position for welding involves identifying the center of gravity of the area in which the multiple components are located from the contour information about the area in which the multiple components are located, and determining the start position using the identified center of gravity.

[0008] According to one aspect of the present invention, a plurality of members can be appropriately welded together.

[0009] FIG. 1 is a schematic diagram of a welding device. FIG. 2 is a diagram illustrating a welding torch. FIG. 3 is a schematic diagram illustrating the positional relationship between a stator terminal and a busbar terminal, which are objects to be welded. FIG. 4 is a diagram illustrating the arrangement of a busbar terminal when the stator terminal and the busbar terminal are fusion-joined. FIG. 5 is a diagram illustrating misalignment between the stator terminal and the busbar terminal. FIG. 6 is a diagram illustrating the start position of welding. FIG. 7 is a schematic diagram illustrating the relationship between the start position of welding and a molten ball formed during welding. FIG. 8 is a schematic diagram illustrating the relationship between the start position of welding and a molten ball formed during welding. FIG. 9 is a schematic diagram illustrating the relationship between the start position of welding and a molten ball formed during welding. FIG. 10 is a diagram illustrating the arrangement of a 3D camera. FIG. 11 is a diagram illustrating a captured image obtained by imaging with a 3D camera. FIG. 12 is a diagram illustrating identification of the contour of each pixel constituting the captured image and the relationship between the pixel and distance information. FIG. 13 is a diagram illustrating setting the start position of welding. FIG. 14 is a diagram illustrating setting the start position of welding. FIG. 15 is a diagram illustrating setting of the welding start position. FIG. 16 is a diagram illustrating setting of the welding start position. FIG. 17 is a diagram illustrating positional misalignment between the stator-side terminal and the busbar-side terminal. FIG. 18 is a diagram illustrating correction of the welding torch position. FIG. 19 is a flowchart of a process for determining the welding start position. FIG. 20 is a diagram illustrating the shape of the tip end of the electrode rod. FIG. 21 is a diagram illustrating a modified example of setting of the welding start position. FIG. 22 is a diagram illustrating setting of the welding start position when the total number of multiple members is three. FIG. 23 is a diagram illustrating a modified example of setting of the welding start position when the total number of multiple members is three. FIG. 24 is a diagram illustrating setting of the welding start position when the total number of multiple members is three. FIG. 25 is a diagram illustrating a modified example of the shape of the terminal set to be welded. FIG. 26 is a diagram illustrating a modified example of the shape of the terminal set to be welded. FIG. 27 is a diagram illustrating a modified example of the shape of the terminal set to be welded.

[0010] Hereinafter, an embodiment of the present invention will be described taking as an example a welding device 1 used to fusion-join (weld) corresponding terminals Tb on the bus bar side and terminals Ts on the stator side. Fig. 1 is a schematic diagram of the welding device 1. Fig. 2 is a diagram illustrating a welding torch 2.

[0011] As shown in Fig. 1, welding apparatus 1 includes a welding torch 2, a drive mechanism 3, a 3D camera 4, and a control device 5. Welding apparatus 1 performs TIG welding of a workpiece using welding torch 2 while spraying inert gas onto the weld area. As shown in Fig. 2, welding torch 2 has an electrode rod 22 protruding from the tip of nozzle portion 21. The tip side of electrode rod 22 has a tapered shape that becomes smaller in outer diameter toward the tip. The tip side of electrode rod 22 is inclined at a predetermined angle θ with respect to a straight line Za along the opposing direction between welding torch 2 and the workpiece (terminals Ts, Tb).

[0012] The welding torch 2 emits a shielding gas from the tip of the nozzle 21 while generating an arc discharge from the tip of the electrode rod 22. This melts and welds the workpieces. Here, the shielding gas is, for example, an inert gas such as argon. The shielding gas serves to transport the energy of the plasma arc generated by the welding torch 2 (electrode rod 22) to the area to be welded and to prevent oxygen in the atmosphere and other oxygen from interfering with the welded area.

[0013] The drive mechanism 3 positions the welding torch 2 at specified coordinates based on instructions from the control device 5. The specified coordinates are the initial position of the welding torch 2 (welding start position Ps) when welding the workpiece. As an example, the drive mechanism 3 may be a multi-joint robot arm or a Cartesian robot that holds the welding torch 2. A Cartesian robot is an industrial robot composed of three mutually perpendicular sliding axes. A Cartesian robot can also position the held welding torch 2 at the welding start position Ps. The 3D camera 4 is a conventionally known 3D camera that captures images of the workpiece and outputs image data capable of generating a 3D image. In this embodiment, the portion of the workpiece (terminals Ts, Tb) facing the welding torch 2 (the upper end faces of terminals Ts, Tb in FIG. 2 ) is imaged from the direction of a straight line Za. The straight line Za is a straight line that runs along the direction in which the workpiece (terminals Ts, Tb) and the welding torch 2 face each other. The 3D camera 4 may also be held by another multi-joint robot arm and moved to specified coordinates.

[0014] The control device 5 is a control device that controls welding by the welding torch 2, imaging by the 3D camera 4, and processing of the images captured by the 3D camera 4. In the control device 5, a processing unit 51, a storage unit 52, and an input / output port 53 are connected via a bus 50.

[0015] An input device 54 and an output device 55 are connected to the input / output port 53. The input device 54 is an interface that can input instructions to the control device 5, and examples of the input device 54 include a mouse, a keyboard, a touch panel, and a terminal carried by a worker. The output device 55 is an interface that can output information, and examples of the output device 55 include a monitor, a speaker, and a terminal carried by a worker.

[0016] The storage unit 52 is a recording medium capable of retaining and rewriting information, such as an HDD, an SSD, a memory, etc. The processing unit 51 is a processor such as a CPU or an MPU, and executes processing defined by a program based on the program stored in the storage unit 52.

[0017] The processing unit 51 has functional blocks including a welding control unit 511 and a start position determination unit 512. The welding control unit 511 controls the drive mechanism 3 to position the welding torch 2 at designated coordinates. The welding control unit 511 positions the welding torch 2 at a welding start position Ps (designated coordinates) described below, and after starting welding, maintains the welding torch 2 in the same position until welding is completed. Furthermore, the welding control unit 511 controls the amount of current flowing through the electrode 22, the time for current flow, the amount of inert gas sprayed, and the like to perform TIG welding of the welding object. The welding control unit 511 changes the amount of current flowing through the electrode 22, the time for current flow, the amount of inert gas sprayed, and the like depending on the area of ​​the portion of the member to be welded (terminals Ts, Tb) facing the welding torch 2.

[0018] The start position determination unit 512 determines the initial position (welding start position) of the welding torch 2 when welding the workpieces.

[0019] Here, we will explain the workpieces to be welded by the welding device 1 according to this embodiment. Fig. 3 is a schematic diagram illustrating the positional relationship between the terminal Tb on the bus bar 8 side, which is the workpiece, and the terminal Ts on the stator S side. For ease of explanation, Fig. 3 omits illustration of one side (the left side in the figure) of the bus bar 8 placed on the housing HS, separated by the diameter line Lz of the cylindrical housing HS.

[0020] In this embodiment, the terminals Ts on the stator S side and the terminals Tb on the bus bar 8 side of the vehicle motor are the welding workpieces to be welded together. As shown in FIG. 3 , the stator S of the vehicle motor M has a cylindrical base S1 (stator core). The base S1 is fixed to the inner periphery of a cylindrical housing HS (peripheral wall 10). A region S2 (indicated by cross-hatching in FIG. 3 ) on the inner diameter side of the base S1 is a region where windings, which are electrical conductors, are provided. The windings are made of a conductive metal material, such as copper. In the motor M, the rotor R is disposed inside this region S2.

[0021] At one end of the stator S (the end on the near side of the paper in FIG. 3 ) when viewed from the opening direction of the housing HS, terminals Ts for connection to the bus bars 8 are drawn out from the winding region S2. In this embodiment, as an example, a total of 24 terminals Ts are drawn out from the winding region S2. The drawn-out terminals Ts are divided into an inner diameter side and an outer diameter side, with 12 terminals Ts arranged on each side.

[0022] On the inner diameter side and the outer diameter side, two terminals are arranged in pairs (hereinafter also referred to as terminal pairs) at a predetermined interval in the circumferential direction around the axis Z. Here, the axis Z is a straight line concentric with the rotation axis of the rotor R. When viewed from the opening direction of the housing HS (stator S), the axis Z is located at the center of the stator S. In the following explanation, the positional relationship of each component will be explained based on the axis Z, as necessary.

[0023] When viewed from the opening direction of the housing HS (stator S), the inner diameter side terminal Ts is located on an imaginary circle Im2 centered on the axis Z. The outer diameter side terminal Ts is located on an imaginary circle Im1 centered on the axis Z. The inner diameter side terminal Ts and the outer diameter side terminal Ts are provided with a phase shift in the circumferential direction around the axis Z.

[0024] In this embodiment, in order to connect each terminal Ts on the stator S to a corresponding terminal Tb on the bus bar 8, the terminals Ts on the stator S are arranged on the inner diameter side and the outer diameter side in a positional relationship as shown in FIG. 3 . The bus bar 8 is a component for connecting the multiple terminals Ts on the stator S to a power supply line on the inverter (not shown) side. When viewed from the front, the bus bar 8 has a substantially arc-shaped base 81. Contact support portions 82 are provided on the outer periphery 81a of the base 81. A plurality of contact support portions 82 are provided at predetermined intervals in the longitudinal direction of the base 81 (the left-right direction in the drawing). Connection terminals 82a are exposed at the tip of the contact support portion 82. Power supply lines extending from the inverter (not shown) are connected to these terminals 82a.

[0025] A plurality of terminal sets 83 and a plurality of terminal sets 84 are provided on the inner periphery 81b of the base 81. Each terminal set 83 is composed of a pair of terminal pieces 831, 831. The terminal pieces 831 are columnar members extending radially inward from the inner periphery 81b of the base 81. A plurality of terminal sets 83 are provided at predetermined intervals in the longitudinal direction of the base 81 (the left-right direction in the figure).

[0026] The terminal set 84 is composed of a pair of terminal pieces 841, 841. The terminal piece 841 is a columnar member extending radially inward from the inner periphery 81b of the base 81. A plurality of terminal sets 84 are provided at predetermined intervals in the longitudinal direction of the base 81 (the left-right direction in the drawing).

[0027] The terminal pieces 831 and 841 have a basic shape with their tip ends bent. The tip ends of the terminal pieces 831 and 841 are bent in the same direction (toward the viewer in the drawing). The bent ends of the terminal pieces 831 and 841 form terminals Tb and Tb that are connected to the terminal Ts on the stator S side. In the base 81, the terminal Tb on the terminal set 84 side is located radially inward relative to the terminal Tb on the terminal set 83 side.

[0028] Here, the terminal pieces 831, 841 constituting the terminal sets 83, 84 are members made of a conductive metal material, for example, copper. The base ends of the terminal pieces 831, 841 are embedded inside the base 81 and are connected to the corresponding terminals 82a of the contact support part 82. By connecting the terminal Ts on the stator S side to the terminal Tb on the bus bar 8 side, the terminal Ts on the stator S side is connected via the bus bar 8 to a power supply line extending from an inverter (not shown).

[0029] Fig. 4 is a diagram illustrating the arrangement of terminals Ts and Tb when the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side are fusion-joined. Fig. 4 schematically illustrates a cross section taken along line A-A in Fig. 3. Fig. 5 is a diagram illustrating misalignment between the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side.

[0030] When welding the terminals Ts on the stator S to the terminals Tb on the busbar 8, the terminals Tb on the busbar 8 are positioned, for example, through the following procedure: (I) The housing HS containing the stator S is placed so that the opening of the housing HS faces upward (in the Z direction). Next, (II) the ends of the windings drawn out from the winding region S2 are bent, and the terminals Ts on the windings are placed at positions where they will be joined to the terminals Tb on the busbar 8. Then, (III) the busbar 8 is placed on the upper end of the housing HS, and each terminal Tb on the busbar 8 is placed at a position where it will be joined to the corresponding terminal Ts on the stator S (see FIGS. 3 and 4 ).

[0031] Here, the terminals Ts on the outer diameter side of the stator S are arranged by bending the ends of the windings drawn out from the winding region S2 toward the outer diameter side of the winding region S2, and then further bending them circumferentially so that the terminal sets are arranged at approximately equal intervals in the circumferential direction, to the position shown in Fig. 3. Similarly, the terminals Ts on the inner diameter side are arranged by bending the ends of the windings drawn out from the winding region S2 so that the terminal sets are arranged at approximately equal intervals in the circumferential direction, to the position shown in Fig. 3. Therefore, bending stress acts on the inner diameter side terminals Ts and the outer diameter side terminals Ts, and when the bus bar 8 is assembled, there is variation in the relative positional relationship between each terminal Ts and the terminal Tb on the bus bar 8 side.

[0032] As shown in Fig. 4 , when performing fusion joining, it is preferable that the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side are parallel to each other and in contact with each other without any gaps. However, due to the bending stress described above, the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side may be arranged with an inclination or a gap (see Fig. 5 ). For this reason, in this embodiment, a pair of clamping jigs 9, 9 (see Fig. 2 ) are used to arrange the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side closer to each other. The pair of clamping jigs 9, 9 are located on both sides of the opposing direction of the terminal Ts and the terminal Tb (the left-right direction in Fig. 2 ) and urge the terminal Tb and the terminal Ts in a direction toward each other.

[0033] Here, we will explain the welding start position Ps (welding start point) when welding terminals Ts and Tb together. FIG. 6 is a diagram illustrating the welding start position Ps. FIG. 6 schematically illustrates the state of the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side, as viewed from the direction of arrows A-A in FIG. 4. FIGS. 7 to 9 are schematic diagrams illustrating the relationship between the welding start position Ps and the molten ball C formed during welding. FIG. 7 illustrates the formation of the molten ball C when the welding start position Ps is set at the boundary line L1 between terminals Ts and Tb. FIG. 8 illustrates the formation of the molten ball C when the welding start position Ps is set on the terminal Tb side. FIG. 9 illustrates the formation of the molten ball C when the welding start position Ps is set at a position where the molten ball C is formed in an ideal shape.

[0034] 6, in this embodiment, the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side have different shapes when viewed from the welding torch 2 side. Specifically, the terminal Tb has a substantially square shape, while the terminal Ts has a rectangular shape. The terminals Tb and Ts have different thicknesses Wb1 and Ws1 in the joining direction (the left-right direction in FIG. 6: the X direction) and different thicknesses Wb2 and Ws2 in the direction perpendicular to the joining direction (the up-down direction in FIG. 6: the Y direction).

[0035] 7, when welding the terminals Tb and Ts together, an arc discharge is generated from the welding torch 2 toward the upper ends of the terminals Tb and Ts. This melts the base material at the upper ends of the terminals Tb and Ts, and the materials mix together to form a molten ball C. When this molten ball C solidifies, the terminals Tb and Ts are connected to each other.

[0036] Typically, when welding two members that have the same cross-sectional area as viewed from the welding torch 2, the welding start position Ps is set on the boundary line between the two members in the joining direction and at a position that is approximately the center of the two members in the width direction (the direction perpendicular to the joining direction). This is because the boundary line between the two members has excellent visibility as viewed from the welding torch 2, making it easy to identify the position.

[0037] However, in this embodiment, the terminals Tb and Ts have different thicknesses Wb1 and Ws1 in the joining direction, so if the welding start position Ps is set on the boundary line L1 in the joining direction of the terminals Tb and Ts (the left-right direction: X direction in FIG. 6 ), the terminal Tb side will not be heated sufficiently during welding, resulting in uneven distribution of the molten ball C (see FIG. 7 ).

[0038] Therefore, if the welding start position Ps is moved toward the thicker terminal Tb (left side in Figure 6), the heating range r centered on the start position Ps moves toward the terminal Tb. As a result, the amount of melted material in the terminal Tb increases, reducing the uneven distribution of the molten ball C during welding. However, if the welding start position Ps is moved too far away from the terminal Ts, the uneven distribution of the molten ball C on the terminal Tb side increases (see Figure 8). Figure 8 shows the state of the molten ball C when the welding start position is moved to the position indicated by the symbol Ps' in Figure 6.

[0039] Similarly, the terminals Tb and Ts have different thicknesses Wb2 and Ws2 in the direction perpendicular to the joining direction (the vertical direction in FIG. 6: the Y direction). Therefore, if the welding start position Ps is simply set on the center line C1 of the terminal Tb in the direction perpendicular to the joining direction of the terminals Tb and Ts (the vertical direction in FIG. 6), the molten ball C generated during welding may be unevenly distributed.

[0040] Here, it is preferable that the molten ball C is formed evenly across both of the members to be welded (terminals Tb, Ts) (see FIG. 9 ). Therefore, it is preferable to heat the members to be welded (terminals Tb, Ts) approximately evenly. The terminals Tb, Ts have different shapes and areas when viewed from the welding torch 2 side. That is, in this embodiment, terminals Tb, Ts with different shapes and areas are welded together. Therefore, simply moving the welding start position Ps in the joining direction (X direction) may not properly form the molten ball C across the terminals Tb, Ts.

[0041] Therefore, in this embodiment, the welding start position Ps is determined in consideration of the area and positional relationship of the regions of the terminals Tb and Ts when viewed from the welding torch 2. Specifically, the welding start position Ps is determined using the center of gravity of the regions of the terminals Tb and Ts when viewed from the welding torch 2.

[0042] Here, the determination of the welding start position Ps using the center of gravity will be described. Fig. 10 is a diagram illustrating the arrangement of the 3D camera 4. Fig. 11 is a diagram illustrating a captured image obtained by imaging with the 3D camera 4. Fig. 12 is a diagram illustrating the identification of the contour of each pixel constituting the captured image and the relationship between the pixel and distance information. Fig. 13 is a diagram illustrating the area surrounded by the contour and the setting of the welding start position Ps.

[0043] 10 , in this embodiment, before welding begins when terminals Tb, Ts are held by clamping jigs 9, 9, the portions of terminals Tb, Ts facing welding torch 2 are imaged by 3D camera 4. Specifically, with welding torch 2 positioned at a distance from above terminals Tb, Ts, 3D camera 4 is positioned above terminals Tb, Ts to image the area where terminals Tb, Ts are located as viewed from the welding torch 2 side.

[0044] As a result, a planar image showing the upper ends of the terminals Tb and Ts (portions facing the welding torch 2) is acquired, as shown in FIG. 11 . The start position determination unit 512 of the welding device 1 performs conventionally known image processing (e.g., image processing using an edge filter) to extract the contours of the areas of the terminals Tb and Ts. Specifically, the start position determination unit 512 identifies pixels Px_b located on the contour of the terminal Tb and pixels Px_s located on the contour of the terminal Ts among the pixels Px constituting the captured image. Then, a set of the identified pixels is extracted as the contour lines Lnb and Lns of the terminals Tb and Ts. Information indicating which pixels among the pixels constituting the captured image correspond to the contour lines Lnb and Lns corresponds to the contour information.

[0045] 12 shows an enlarged view of the pixel Px_b region corresponding to the contour of terminal Tb, the pixel Px_s region corresponding to the contour of terminal Ts, and the overlapping region between them. By extracting the pixels corresponding to the contours, a contour line Lnb defining the contour of the range of terminal Tb and a contour line Lns defining the contour of the range of terminal Ts are extracted with a partial overlapping range, as shown in FIG.

[0046] In the case of Figure 12, one side of the contour line Lnb of terminal Tb completely overlaps the contour line Lns of terminal Ts. That is, the area surrounded by the contour line Lnb of terminal Tb and the area surrounded by the contour line Lns of terminal Ts have a range where they intersect. Therefore, the area surrounded by the contour line Lnb of terminal Tb and the area surrounded by the contour line Lns of terminal Ts can be considered as a single area. In this case, the start position determination unit 512 of the welding device 1 determines the contour line Ln (see Figure 13) that passes through the outermost periphery of the area surrounded by the contour line Lnb of terminal Tb and the area surrounded by the contour line Lns of terminal Ts as the contour line that defines the area of ​​the workpiece (terminals Tb, Ts).

[0047] Once a region surrounded by the contour line Ln is determined, the start position determination unit 512 calculates the center of gravity G of the region surrounded by the contour line Ln. The calculated center of gravity G is then determined as the welding start position Ps. The center of gravity G is the center of gravity when the regions of terminals Tb and Ts are considered as a single region. When welding is performed using center of gravity G as the start position Ps, the welding heat spreads from the center of gravity G to the surrounding area. As a result, the heat spreads approximately evenly at the upper ends of terminals Tb and Ts, forming a molten ball C in which the base material is approximately evenly melted, thereby properly welding terminals Tb and Ts. In other words, even when terminals Ts and Tb have different shapes (areas) of the portions facing the welding torch 2, the welding start position Ps is determined taking into account the difference in shape (area), allowing terminals Tb and Ts to be properly welded. The center of gravity is, for example, the area center of gravity.

[0048] 13 illustrates an ideal joining state in which one side of the joining surface of terminal Tb is joined to one side of the joining surface of terminal Ts over the entire surface. The clamping jigs 9, 9 are abutted at positions offset from the upper ends of terminals Tb and Ts to be welded together, taking into account melting of the base materials during welding. Therefore, the upper ends of terminals Tb and Ts are not properly restrained, and the state before welding does not necessarily result in an ideal joining state.

[0049] In this embodiment, when the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be considered as a single area surrounded by a single contour line (A), the welding start position Ps is set using the center of gravity of the area surrounded by the contour line. Here, the case where the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be considered as a single area surrounded by a single contour line (A) is not limited to the case where the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns are adjacent and in complete contact with each other. For example, even if there is a gap or misalignment between the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns, if the gap or misalignment between the terminal Ts and the terminal Tb is large enough to prevent welding. Here, a gap that does not interfere with welding means that the gap between the terminal Ts and the terminal Tb is large enough to prevent the inflow of the molten ball C generated by the melting of the base material. A "gap that interferes with welding" refers to a gap between terminals Ts and Tb that is large enough to prevent the inflow of molten balls C generated by melting the base material. If the gap is too large, the molten balls C cannot remain at the ends of terminals Ts and Tb, and instead flow into the gap. This interferes with welding between terminals Ts and Tb. Furthermore, a misalignment that does not interfere with welding refers to a misalignment that causes the molten balls C generated by melting the base material to form across terminals Ts and Tb. Therefore, if the molten balls C form at the end of one of terminals Ts and Tb, or if they are unevenly distributed between terminals Ts and Tb, this constitutes a misalignment that interferes with welding.

[0050] The size of the gap and the positional deviation used to determine whether or not there is a problem are determined according to the surface tension, fluidity, viscosity, etc. of the molten base material. In this embodiment, the size of the gap (threshold value) used to determine whether or not there is a problem is determined through experiments and simulations.

[0051] 14 to 16 are diagrams illustrating an example of setting the welding start position Ps based on the area surrounded by the contour line Lnb and the contour line Lns. FIG. 17 is a diagram illustrating the positional misalignment between the terminal Ts on the stator S side and the terminal Tb on the bus bar 8 side. FIG. 18 is a diagram illustrating the correction of the position of the welding torch 2. Here, FIGS. 14 to 16 show an example corresponding to the case where the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be regarded as (A) one area surrounded by one contour line.

[0052] Here, when the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be regarded as one area surrounded by one contour line, this is the same as when multiple components are regarded as one component when viewed from the welding torch 2 side.

[0053] 14, when the contour line Lnb and the contour line Lns have a range where they overlap while being misaligned in the Y direction, the relationship (A) above is satisfied. In such a case, the start position determination unit 512 identifies the maximum contour line Ln that connects the outermost periphery of the area surrounded by the contour line Lnb and the contour line Lns, and determines the center of gravity G of the area surrounded by the identified maximum contour line Ln as the welding start position Ps.

[0054] As shown in FIG. 15 , when the contour lines Lnb and Lns are in point contact on one side in the Y direction but are misaligned in the X direction on the other side, the distance d at the point where the distance between the contour lines Lnb and Lns in the X direction is greatest is calculated and compared with a threshold value Tha. If the distance d is equal to or less than the threshold value Tha (Tha≧d), the relationship (A) is determined to be true. In this case, the start position determination unit 512 identifies the largest contour line Ln that connects the outermost periphery of the area surrounded by the contour lines Lnb and Lns, and determines the center of gravity G of the area surrounded by the identified largest contour line Ln as the welding start position Ps. In this case, in the portion where the contour lines Lnb and Lns are spaced apart, for example, the shortest distance is connected between the corner P1 of the contour line Lnb and the corner P2 of the contour line Lns, thereby maximizing the area of ​​the area surrounded by the largest contour line Ln.

[0055] As shown in FIG. 16 , when the contour lines Lnb and Lns are separated without any contact, the distance d at the point where the distance between the contour lines Lnb and Lns in the X direction is greatest is calculated and compared with a threshold value Tha. If the distance d is equal to or less than the threshold value Tha (Tha≧d), the relationship (A) is determined to be true. In this case, the start position determination unit 512 identifies the largest contour line Ln that connects the outermost periphery of the area surrounded by the contour lines Lnb and Lns, and determines the center of gravity G of the area surrounded by the identified largest contour line Ln as the welding start position Ps. In this case, in the portion where the contour lines Lnb and Lns are spaced apart, the corners P1 and P4 of the contour line Lnb are connected to the corners P2 and P3 of the contour line Lns, respectively, by the shortest distance, thereby maximizing the area of ​​the area surrounded by the largest contour line Ln.

[0056] If the distance d is greater than the threshold value Tha (Tha<d), it is determined that the current arrangement of the terminals Tb and Ts does not allow proper welding of the terminals. This is because the gap between the area surrounded by the outline Lnb and the area surrounded by the outline Lns is large, and the generated molten ball C falls into the gap. In this case, the area surrounded by the outline Lnb and the area surrounded by the outline Lns cannot be considered as a single, unified area. In other words, the distance d exceeds the threshold value at which the terminals Tb and Ts can be considered as a single member. In such a case, an alarm is output from the output device 55, and the welding device 1 is stopped automatically or upon receiving an instruction from the input device 54.

[0057] As described above, the relative positional relationship between the terminals Tb and Ts can be misaligned not only in the X and Y directions but also in the Z direction. Therefore, even when the captured image shown in FIG. 11 is obtained, the terminals Tb and Ts may be positioned with a misalignment in the Z direction, as shown in FIG. 17 . Therefore, the start position determination unit 512 calculates the separation distance Dz in the Z direction between the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns. As described above, the processed image (see FIG. 12 ) obtained by processing the captured image contains distance information that can identify the distance from the 3D camera 4 for each pixel constituting the image. Therefore, by referring to the distance information held by each pixel in the processed image ( FIG. 12 ), the misalignment (separation distance Dz) between the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns in the front-to-back direction of the page can be identified.

[0058] Here, the calculation of the separation distance Dz is performed, for example, by the following method: (a) Calculating the difference between the average value of the distance to each pixel included in the area surrounded by the contour line Lnb and the average value of the distance to each pixel included in the area surrounded by the contour line Lns, and setting the calculated difference as the separation distance Dz; (b) Extracting the combination of pixels included in the area surrounded by the contour line Lns and pixels included in the area surrounded by the contour line Lnb that results in the maximum separation distance, and setting the Z-direction distance between the pixels of the extracted combination as the separation distance Dz.

[0059] The start position determiner 512 compares the calculated separation distance Dz with a threshold value Th_z. If the calculated separation distance Dz is greater than the threshold value Th_z (Dz>Th_z), the start position determiner 512 does not determine the welding start position Ps. This is because the separation distance between the terminals Tb and Ts may be too large, making it impossible to properly perform welding.

[0060] In this embodiment, even in the case of (A) above, if the separation distance Dz is greater than the threshold value Th_z, the welding start position Ps is not determined. If the calculated separation distance Dz is equal to or less than the threshold value Th_z (Dz≦Th_z), the welding start position Ps is determined and welding is performed.

[0061] In this way, when welding terminals Ts and Tb that have different shapes (areas) of the portions facing the welding torch 2, and if welding is possible even if there is a positional misalignment between the terminals Ts and Tb, the welding start position Ps is determined taking into account the difference in shape (area) and the positional misalignment. This allows the terminals Ts and Tb to be welded more appropriately.

[0062] When welding torch 2 is placed at start position Ps to perform welding, welding torch 2 is set at a position spaced a height ha from terminals Tb and Ts (see FIG. 18 ). However, depending on the degree of misalignment of terminals Tb and Ts in the Z direction, start position Ps may be placed too close to terminals Tb and Ts or too far from terminals Tb and Ts. In such cases, uneven melting of terminals Tb and Ts may occur. Here, as an example, start position determination unit 512 may correct the Z-direction position of start position Ps in accordance with separation distance Dz when calculated distance Dz is greater than or equal to threshold value Th_z1 and less than or equal to threshold value Th_z (Th_z1≦Dz≦Thz).

[0063] As shown in Figure 18 , when the welding start position Ps is set above the terminal Tb, the start position Ps is positioned at an initial position that is a height ha above the terminal Tb. If the terminal Tb is positioned higher than the intended position by a height hb, the position of the welding torch 2 is offset upward by the height hb from the initial position, so that the distance between the welding torch 2 (electrode rod 22) and the terminal Tb is the intended height ha (see the upper right diagram in Figure 18 ). If the terminal Tb is positioned lower than the intended position by a height hb, the position of the welding torch 2 is offset downward by the height hb from the initial position, so that the distance between the welding torch 2 (electrode rod 22) and the terminal Tb is the intended height ha (see the lower right diagram in Figure 18 ). By doing this, it is possible to preferably prevent a situation in which the amount of melting of terminals Tb and Ts differs during welding due to a positional misalignment of terminal Tb in the Z direction, causing problems in welding terminals Ts and Tb together.

[0064] 19 is a flowchart of the basic processing for determining the welding start position Ps. When the terminals Ts, Tb to be welded to each other are gripped by the clamp jigs 9, 9 and preparations for welding using the welding torch 2 are completed (step S101, Yes), an image is captured by the 3D camera 4 (step S102). Specifically, the 3D camera 4, positioned above the terminals Tb, Ts, captures an image of a range including the portions of the terminals Tb, Ts facing the welding torch 2. As a result, the captured image (see FIG. 11 ) is input to the processing unit 51 of the welding device 1.

[0065] The start position determination unit 512 of the processing unit 51 processes the input captured image to extract the contours of the areas of the terminals Tb and Ts (plurality of members to be welded) (step S103), thereby extracting a contour line Lnb surrounding the area of ​​the terminal Tb and a contour line Lns surrounding the area of ​​the terminal Ts (see FIGS. 12, 14, 15, and 16).

[0066] Next, the start position determination unit 512 calculates the separation distance Dz in the Z direction between the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns (step S104).

[0067] If the calculated separation distance Dz is greater than the threshold value Th_z (Dz>Th_z) (No in step S105), start position determiner 512 proceeds to step S106 and performs error processing. This is because the separation distance Dz between terminals Tb and Ts is too large, and there is a possibility that welding will not be performed properly. In the error processing, as an example, output device 55 outputs a message indicating that "there is a possibility that welding will not be performed properly" (error notification). As a result, welding device 1 stops automatically or waits for an instruction input from input device 54.

[0068] If the calculated separation distance Dz is less than or equal to the threshold value Th_z (Dz≦Th_z) (step S105, Yes), the start position determination unit 512 checks whether the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be perceived as a single, unified area (S107).

[0069] If the area can be regarded as a single unified region (step S107, Yes), the outermost contour line Ln enclosed by the contour line Lnb and the contour line Lns is determined as the contour line defining the area of ​​the workpiece (terminals Tb, Ts). Once the area enclosed by the contour line Ln is determined, the start position determiner 512 determines the center of gravity G of the area enclosed by the contour line Ln as the welding start position Ps (step S108).

[0070] On the other hand, if the area cannot be recognized as one unified region (No at step S107), the process proceeds to step S106, where error processing is executed (error notification).

[0071] In this way, when welding terminals Ts and Tb that have different shapes (areas) of the portions facing the welding torch 2, and if welding is possible even if there is a positional misalignment between the terminals Ts and Tb, the welding start position Ps is determined taking into account the difference in shape (area) and the positional misalignment. This allows the terminals Ts and Tb to be welded more appropriately.

[0072] 20 is a diagram illustrating the shape of the tip end of the electrode rod 22. In the above-described embodiment, the tip end of the electrode rod 22 of the welding torch 2 is tapered at a predetermined angle θ with respect to the straight line Za. The crossing angle (angle θ) of the electrode rod 22 with respect to the straight line Za may be changed depending on the area of ​​the terminals Tb and Ts, which are the workpieces to be welded.

[0073] Here, if the angle θ of the tip of the welding torch 2 (electrode rod 22) with respect to the line Za (vertical line) along the opposing direction of the welding torch 2 and the terminals Tb and Ts is small, the current moving from the tip of the welding torch 2 toward the base metal is diffused. In this case, the area through which the current flows is widened, and as a result, even if there is a slight gap between the terminals Tb and Ts or if there is a slight misalignment between the terminals Tb and Ts, the terminals Tb and Ts can be melted and joined together. In other words, the robustness of the welding is improved. On the other hand, if the angle θ of the tip of the welding torch 2 with respect to the line Z2 is large, the current moving from the tip of the welding torch 2 toward the base metal is concentrated in a limited area. In this case, the area through which the current flows is narrowed, and as a result, energy is locally concentrated at the terminals Ts and Tb (the energy density is increased). As a result, if there is a gap between the terminals Ts and Tb or if there is a slight misalignment between the terminals Ts and Tb, the welding may be insufficient. Therefore, by setting the angle θ at the tip of the welding torch 2 (electrode rod 22) taking into consideration the gap that may occur between the terminals Ts and Tb and the positional misalignment of the terminals Ts and Tb, the terminals Ts and Tb can be properly welded together even if there is a slight gap or positional misalignment between the terminals Ts and Tb.

[0074] As shown in FIG. 20 , when the angle θ is reduced to θ′, the diameter W of the area of ​​the current (arc) emitted from the electrode rod 22 increases to W′. Therefore, when the area of ​​the workpiece (terminals Tb, Ts) facing the welding torch 2 is small, increasing the angle θ allows the current to be concentrated in the necessary areas of the workpiece (terminals Tb, Ts), thereby shortening the time required for welding. Furthermore, when the area of ​​the workpiece (terminals Tb, Ts) facing the welding torch 2 is large, decreasing the angle θ increases the area of ​​the arc, allowing the workpiece (terminals Tb, Ts) to melt almost uniformly. This effectively prevents insufficient welding.

[0075] In the above-described embodiment, an example was given in which the area of ​​one set of terminals (terminals Ts, Tb) to be welded to each other is imaged in step S102. Multiple sets of terminals may be imaged simultaneously. For example, the area surrounded by the thin lines in FIG. 3 includes four sets of terminals (Ts, Ts) to be welded to each other, and the area surrounded by the thin lines may be the imaging range. Alternatively, all sets of terminals may be imaged simultaneously. In particular, when connecting the terminal Ts on the vehicle motor M side and the terminal Tb on the bus bar 8 side, the fewer times the images of the set of terminals to be welded to each other are imaged, the shorter the processing time, which is expected to reduce the manufacturing costs of the motor M.

[0076] In the above-described embodiment, an example is given of capturing images using the 3D camera 4. Two cameras may be used to capture images of the portions of the terminals Tb and Ts facing the welding torch 2, and a processed image having distance information may be generated from the captured images by using a conventionally known three-dimensional measurement method based on a stereo method. Also, instead of the 3D camera 4, a LiDAR sensor may be used to capture the processed image having distance information.

[0077] 21 is a diagram illustrating a modified example of setting the welding start position Ps based on the area surrounded by the contour line Lnb and the contour line Lns. In the above-described embodiment, when the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns can be regarded as one area surrounded by one contour line, the center of gravity of the one area surrounded by one contour line is set as the welding start position Ps.

[0078] Specifically, when the distance d between the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns is maximum and the distance d is equal to or less than the threshold value Tha (Tha≧d), the area surrounded by the contour line Lnb and the area surrounded by the contour line Lns are regarded as a single area surrounded by a single contour line. Here, when the distance d is large enough to allow the molten ball C to remain at the ends of the terminals Ts and Tb, that is, when the distance d is equal to or less than the threshold value Tha, the welding start position Ps may be determined as follows.

[0079] 21 , when the contour line Lnb and the contour line Lns are separated without any contact, the distance d at the point where the distance between the contour line Lnb and the contour line Lns in the X direction is greatest is calculated and compared with the threshold value Tha. If the distance d is smaller than the threshold value Tha (Tha≧d), the start position determination unit 512 identifies the center of gravity G of the contour line Lnb and the center of gravity G of each area enclosed by the contour line Lns. The midpoint of the straight line Lg connecting the identified centers of gravity G and G is determined as the welding start position Ps.

[0080] With this configuration, the terminals Ts and Tb can be properly welded together even if there is a slight gap or misalignment between them.

[0081] In the above-described embodiment, the plurality of components to be welded together is a pair of terminals Ts and Tb. However, the plurality of components may be three or more. Figures 22 to 24 are diagrams for explaining how to determine the welding start position Ps when the total number of the plurality of components is three.

[0082] If the total number of multiple members increases, the contour lines (Ln_TG1, Ln_TG2, Ln_TG3) of each member (TG1, TG2, TG3) are identified. If the area surrounded by the contour lines (Ln_TG1, Ln_TG2, Ln_TG3) can be considered as (A) one area surrounded by one contour line Ln, the center of gravity G of the area surrounded by one contour line Ln is set as the welding start position Ps (see FIG. 22).

[0083] If the area surrounded by the contour lines (Ln_TG1, Ln_TG2, Ln_TG3) can be considered as an area surrounded by two contour lines, and the distance between the two contour lines Ln, Ln is large enough to allow welding, the center of gravity G of the area surrounded by the contour line Ln and the center of gravity G of the area surrounded by the contour line Ln are identified. Then, the midpoint of the line segment connecting the identified centers of gravity G, G is determined as the welding start position Ps (see FIG. 23).

[0084] If the area surrounded by the contour lines (Ln_TG1, Ln_TG2, Ln_TG3) is recognized as a separate area surrounded by three contour lines, welding is not performed (see FIG. 24).

[0085] In this way, even in the case of three members (TG1, TG2, TG3) to be welded together, the center of gravity is identified from the contour information of the area in the captured image where the three members (TG1, TG2, TG3) are located, and the identified center of gravity is used to determine the welding start position Ps. This allows the three members (TG1, TG2, TG3) to be welded together to be properly welded.

[0086] 25 to 27 are diagrams illustrating modified shapes of the terminal pair to be welded. In the above-described embodiment, a substantially square-shaped terminal Tb and a substantially rectangular-shaped terminal Ts are welded together. The terminal shapes are not limited to those described above. As shown in FIG. 25 , terminals Tb1 and Ts1 may have a thin thickness in the joining direction (X direction). In this case, terminals Tb1 and Ts1 can be properly welded together by increasing the crossing angle (angle θ) of the electrode rod 22 with respect to the line Za or by reducing the current value to reduce the heat input energy. Note that narrowing the welding area by increasing the angle θ or reducing the current value to reduce the heat input energy may result in only a portion of the contact surface being welded, resulting in insufficient strength. In such cases, a new welding position may be set at a position different from the center of gravity within the area of ​​the terminals (terminals Ts and Tb), and the area around the center of gravity may be welded. For example, in FIG. 25, by causing an arc discharge at a position indicated by a white circle other than the center of gravity G, a new location other than the welding start position Ps may be welded, thereby ensuring the welding strength between the terminals (terminals Ts, Tb) to be welded to each other.

[0087] 26, the terminals Tb2 and Ts2 may have significantly different widths in the Y direction. In this case, the heating range can be widened by reducing the angle θ of the electrode rod 22 with respect to the straight line Za or by increasing the current value to increase the heat input energy, thereby properly welding the terminals Tb2 and Ts2 together. Also, as shown in FIG. 27, one terminal Tb3 may be provided with a recess Re into which at least a portion of the other terminal Ts can be inserted. In this case, the terminals Tb3 and Ts3 can also be properly welded together.

[0088] As described above, welding apparatus 1 according to one aspect of the present invention has the following configuration. (1) Welding apparatus 1 is a welding apparatus that welds terminals Ts and Tb (multiple members) to be welded together. Welding apparatus 1 has: welding torch 2; 3D camera 4 (information acquisition unit) that can acquire information about the area in which terminals Ts and Tb are located as viewed from the welding torch 2; and control device 5 (control unit) that controls welding by welding torch 2. Control device 5 has a start position determiner 512 that determines a start position Ps of welding by welding torch 2. Start position determiner 512 identifies the center of gravity of the area in which terminals Ts and Tb are located from contour information of the area in which terminals Ts and Tb are located, and determines the start position using the identified center of gravity.

[0089] According to one aspect of the present invention, the welding start position Ps is determined using the center of gravity G of terminals Ts and Tb (the area where multiple members are located). Compared to simply setting the start position Ps on the boundary line between terminals Ts and Tb, this method can prevent the molten ball C from being displaced unevenly due to melting of the base materials of terminals Ts and Tb during welding, allowing terminals Ts and Tb to be properly welded.

[0090] (2) In (1) above, if the contour information indicates that the area in which the terminals Ts and Tb (multiple components) are located is an area surrounded by a single contour line Ln, the start position determination unit 512 identifies the center of gravity G of the area surrounded by the single contour line Ln and determines the identified center of gravity as the start position Ps.

[0091] According to one aspect of the present invention, even if there is a small gap between the regions of terminals Ts and Tb (multiple components) defined by contour lines Lns and Lnb, as long as the gap is large enough to prevent the inflow of molten ball C, the region surrounded by contour lines Lns and Lnb is recognized as a region surrounded by a single contour line Ln. By determining the center of gravity G of the region surrounded by a single contour line Ln as the starting position Ps, the molten ball C generated by melting the base material of terminals Ts and Tb (each component) during welding is generated so as to span multiple components, centered on the position of the center of gravity G. As a result, the molten base material of terminals Ts and Tb mixes at the location of the molten ball C and then solidifies. This allows the components to mix in the welded region of terminals Ts and Tb (multiple components), reducing the possibility of poor welding that occurs when the components are insufficiently mixed.

[0092] If the welding start position Ps is off-center, the position of the molten ball C, which is generated by the melting of the base materials of the terminals Ts and Tb during welding, will be uneven. In such a case, the molten base material may fall away from the area where the terminals Ts and Tb are gathered, resulting in an insufficient amount of base material to be mixed in the molten state. This may result in poor welding of the welded terminals Ts and Tb. By setting the welding start position Ps at the center of gravity, as in one aspect of this embodiment, this situation can be effectively prevented. In the welded area of ​​the pair of terminals Ts and Tb, the terminals Ts and Tb are mixed together, reducing the possibility of poor welding that occurs when the terminals Ts and Tb are not mixed together sufficiently.

[0093] (3) In (1) above, if the contour information indicates that the areas of terminals Ts and Tb (multiple components) defined by contour lines Lns and Lnb can be recognized as independent areas surrounded by two contours, the start position determination unit 512 determines the midpoint of the line connecting the center of gravity G of one area and the center of gravity G of the other area as the start position Ps.

[0094] Even if it is determined that a pair of components (terminals Ts, Tb) are spaced apart from each other before welding based on the area of ​​terminals Ts, Tb (multiple components) defined by contour lines Lns, Lnb, if the gap between the two regions is large enough to prevent the molten ball C from falling, the midpoint of the line connecting the center of gravity G of one component and the center of gravity G of the other component is set as the welding start position Ps. This allows the molten ball C, generated by melting the base material of terminals Ts, Tb (each component) during welding, to be generated across multiple components without falling into the gap. This allows the terminals Ts, Tb to be properly welded together.

[0095] (4) In the above (2) or (3), the 3D camera 4 (information acquisition unit) can acquire distance information to each of the terminals Ts and Tb (multiple members). The start position determination unit 512 corrects the position of the start position Ps in the direction facing the welding torch 2 (direction of the straight line Za) based on the distance information.

[0096] When welding terminals Ts and Tb (multiple members), if the position of the welding torch 2 is fixed in the direction in which the terminals Ts and Tb face the welding torch 2, and one of the terminals Ts and Tb is positioned closer to the welding torch 2 than the other, the current flowing through one member will be greater than the current flowing through the other member. This can result in insufficient welding of the terminals Ts and Tb. Furthermore, the welding torch 2 may be positioned too far from the terminals Ts and Tb, or the welding torch 2 may interfere with one of the terminals. In such cases, the welding of the terminals Ts and Tb may also be insufficient. Specifically, if the separation distance between the welding torch 2 and the terminals Ts and Tb is too large, the energy input to each of the terminals Ts and Tb during welding decreases. In such cases, the amount (volume) of the base material of the terminals Ts and Tb melts decreases, resulting in a decrease in joint strength after welding. Furthermore, if the distance between the welding torch 2 and the terminals Ts and Tb is too short, excessive energy is input to each of the terminals Ts and Tb during welding. In such a case, the molten ball C generated by the melting of the base materials of the terminals Ts and Tb exceeds the surface tension limit and moves away from the welded portions of the terminals Ts and Tb, resulting in a decrease in joint strength after welding. In the above-described embodiment, distance information to each of the terminals Ts and Tb is acquired, and the welding start position Ps (the position of the tip of the welding torch 2) in the opposing direction between the welding torch 2 and the terminals Ts and Tb is corrected based on the acquired distance information. This corrects the welding start position Ps taking into account variations in the distance to each of the terminals Ts and Tb, i.e., variations in the positions of the terminals Ts and Tb, thereby enabling the terminals Ts and Tb to be properly welded.

[0097] (5) In the above (4), the information acquisition unit is a 3D camera 4.

[0098] According to one aspect of the present invention, the distances to the terminals Ts and Tb can be determined from captured images of the areas where the terminals Ts and Tb are located. This allows the welding start position Ps to be corrected taking into account variations in the positions of the terminals Ts and Tb, thereby enabling the terminals Ts and Tb to be appropriately welded. Processing of the captured images by the 3D camera 4 places a low processing load on the control device 5. This allows the welding position to be determined more easily, enabling appropriate welding.

[0099] (I) In any one of the above (1) to (5), the terminals Ts and Tb have different areas of the portions facing the welding torch 2.

[0100] If the boundary between the terminals Ts and Tb to be welded to each other is set as the welding start position Ps, the areas of the terminals Ts and Tb facing the welding torch 2 are different, so the start position Ps may be determined to be biased toward one of the terminals Ts. In such a case, the other terminal Tb may not be melted sufficiently, resulting in a poor weld. According to one aspect of the present invention, the possibility of such an occurrence can be reduced by determining the center of gravity of the area where the terminals Ts and Tb are located as the start position Ps.

[0101] (II) In any one of (1) to (5) and (I) above, the terminals Ts and Tb include multiple terminals Ts on the stator S (stator coil) side and multiple terminals Tb on the bus bar 8 side. There are multiple terminal sets, each consisting of one terminal Ts on the stator S side and one terminal Tb on the bus bar 8 side. The 3D camera 4 can simultaneously acquire information on the areas of each terminal set included in a predetermined number of terminal sets. The start position determination unit 512 determines a start position Ps for each terminal set from the contour information of each terminal set acquired simultaneously. The welding control unit 511 (control unit) sequentially welds the terminal sets for which the start position Ps has been determined.

[0102] With this configuration, when there are multiple terminal pairs to be welded, the welding start position Ps can be determined for a predetermined number of terminal pairs at once, which is expected to reduce the time required to complete welding of all terminal pairs compared to when terminal pair area information is acquired for each terminal pair and the start position Ps is determined.

[0103] The present invention can be understood as a welding method for welding terminals Ts and Tb (multiple members) together using a welding torch 2. (6) The welding method includes the steps of: acquiring information about the area where terminals Ts and Tb are located as viewed from the welding torch 2; determining a welding start position Ps from contour information about the area where terminals Ts and Tb are located; and moving the welding torch 2 to the start position Ps to weld the terminals Ts and Tb together. In the step of determining the welding start position Ps, the center of gravity G of the area where terminals Ts and Tb are located is identified from the contour information about the area where terminals Ts and Tb are located, and the identified center of gravity G is used to determine the start position Ps.

[0104] According to one aspect of the present invention, compared to when the starting position Ps is simply set on the boundary line between terminals Ts and Tb, the deviation of the molten ball C caused by the melting of the base material of terminals Ts and Tb during welding can be suppressed, thereby allowing terminals Ts and Tb to be properly welded.

[0105] (III) In the step of determining the welding start position Ps in (6) above, if the area where the terminals Ts and Tb are located can be identified as an area surrounded by one contour line Ln based on the contour information, the center of gravity G of the area surrounded by one contour line Ln is identified, and the identified center of gravity G is determined as the start position Ps.

[0106] According to one aspect of the present invention, even if there is a small gap between terminals Ts and Tb (multiple members), as long as the gap is small enough to prevent the inflow of molten ball C, the gap is recognized as an area surrounded by a single contour line Ln. As a result, even if the center of gravity G of the area surrounded by a single contour line Ln is determined as the start position Ps, the molten ball C generated by melting the base material of terminals Ts and Tb (each member) during welding will be generated so as to straddle multiple members with the center of gravity G as its center, allowing terminals Ts and Tb to be properly welded together.

[0107] (IV) In the step of determining the welding start position Ps in (6) above, if the area where the terminals Ts and Tb are located can be identified as an area surrounded by two contours based on the contour information, the midpoint of the line segment Lg connecting the center of gravity G of one area and the center of gravity G of the other area is determined as the welding start position Ps.

[0108] According to one aspect of the present invention, even if it is determined that a pair of components (terminals Ts, Tb) are spaced apart from each other before welding based on the area of ​​terminals Ts, Tb (multiple components) defined by contour lines Lns, Lnb, if the gap between the two regions is large enough to prevent the molten ball C from falling, the midpoint of the line connecting the center of gravity G of one component and the center of gravity G of the other component is set as the welding start position Ps. This allows the molten ball C, generated by melting the base material of terminals Ts, Tb (each component) during welding, to be generated across multiple components without falling into the gap. This allows the terminals Ts, Tb to be properly welded together.

[0109] Although the embodiments of the present invention have been described above, the present invention is not limited to the aspects shown in these embodiments. In the above embodiments, a motor for a vehicle is illustrated, but the present invention can also be applied to motors for devices other than vehicles. The present invention can be modified as appropriate within the scope of the technical concept of the invention.

[0110] 1: Welding device 2: Welding torch 22: Electrode rod 3: 3D camera (information acquisition unit) 5: Control device (control unit) 512: Start position determination unit C: Molten ball G: Center of gravity Lns, Lnb: Contour line (contour information) Ps: Start position (start position of welding) Ts, Tb: Terminals (plural members)

Claims

1. A welding device for welding multiple components together, comprising: a welding torch; an information acquisition unit capable of acquiring information on an area in which the multiple components are located as viewed from the welding torch; and a control unit for controlling welding by the welding torch, wherein the control unit has a start position determination unit that determines a start position for welding by the welding torch, and the start position determination unit identifies the center of gravity of the area in which the multiple components are located from contour information of the area in which the multiple components are located, and determines the start position using the identified center of gravity.

2. A welding device as set forth in claim 1, wherein the start position determination unit, when the contour information indicates that an area in which multiple components are located can be recognized as an area surrounded by a single contour, identifies the center of gravity of the area surrounded by the single contour and determines the identified center of gravity as the start position.

3. A welding device according to claim 1, wherein the start position determination unit determines the midpoint of the line connecting the center of gravity of one area and the center of gravity of the other area as the start position when the area in which multiple components are located can be identified as an area surrounded by two contours based on the contour information.

4. A welding device according to claim 2 or 3, wherein the information acquisition unit is capable of acquiring distance information to each of the plurality of members, and the start position determination unit corrects the position of the start position in the direction facing the welding torch based on the distance information.

5. The welding device according to claim 4, wherein the information acquisition unit is a 3D camera.

6. A welding method for welding a plurality of components together using a welding torch, comprising the steps of: acquiring information about an area in which the plurality of components are located as viewed from the welding torch; determining a start position for welding from contour information about the area in which the plurality of components are located; and moving the welding torch to the start position to weld the plurality of components together, wherein in the step of determining the start position for welding, the center of gravity of the area in which the plurality of components are located is identified from the contour information about the area in which the plurality of components are located, and the identified center of gravity is used to determine the start position.

Images