Welding device

Abstract

A welding device (1) comprises: a drive unit (4S); a first reduction gear (70); a second reduction gear (80); a first welding gun (21); and a second welding gun (22). The drive unit (4S) is disposed coaxially with a rotation shaft (4R) and rotationally drives the rotation shaft (4R). The first reduction gear (70) is disposed coaxially with the rotation shaft (4R), and in a state in which a second output unit (72) is fixed so as to be incapable of rotating, the first reduction gear reduces the rotational power at a first reduction ratio and rotates an outer peripheral surface (73) of a first output unit (71) in a direction opposite a rotational direction of the rotation shaft (4R). The second reduction gear (80) is disposed coaxially with the rotation shaft (4R), and in a state in which a third output unit (81) is fixed to the first output unit (71), the second reduction gear reduces the rotational power at a second reduction ratio and rotates an outer peripheral surface (83) of a fourth output unit (82). The first welding gun (21) is attached to the outer peripheral surface (73) of the first output unit (71). The second welding gun (22) is attached to the outer peripheral surface (83) of the fourth output unit (82).

Description

welding equipment

[0001] The present invention relates to a welding device for welding workpieces.

[0002] Resistance welding is a known welding technique in which an electrode is placed in contact with a workpiece, and current is passed through the workpiece to weld the melted portion of the workpiece due to resistance heating. A device for performing this resistance welding has been proposed, which includes two welding guns positioned on one side of the workpiece, each equipped with an electrode, and in which the distance between the electrodes can be adjusted.

[0003] For example, Patent Document 1 discloses an apparatus in which a rotation shaft portion having a common rotation axis is provided for a fixed welding gun and a movable welding gun, and the movable welding gun is configured to rotate around the rotation shaft portion relative to the fixed welding gun by a drive portion.

[0004] Japanese Patent Application Laid-Open No. 2019-136752

[0005] In a device capable of freely changing the position of a pair of electrodes, such as that described in Patent Document 1, if a drive unit having an axis different from that of the rotation axis that changes the position of the pair of electrodes is provided, the drive unit may interfere with its surrounding structure. For example, if the drive unit is disposed radially outward (around) the rotation axis, the drive unit may interfere with the workpiece or welding gun disposed around the rotation axis. Interference between the workpiece and the drive unit may restrict the shape of the workpiece and its position during welding. Furthermore, interference between the welding gun and the drive unit may restrict the placement of the welding gun. Therefore, depending on the placement of the drive unit, it may be difficult to ensure layout flexibility for the welding device. Therefore, there is room for improvement in ensuring layout flexibility for the welding device.

[0006] The welding apparatus of the present invention was invented in consideration of these problems, and one of its objectives is to ensure layout flexibility of the welding apparatus. However, in addition to this objective, another objective of the present invention is to achieve operational effects derived from the respective configurations shown in the "Mode for Carrying Out the Invention" below, which are not obtainable with conventional techniques.

[0007] The disclosed welding device can be realized as the following disclosed aspects (application examples) and solves at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected as an additional option, and each of the aspects from aspect 2 onwards is an aspect that can be omitted. None of the aspects from aspect 2 onwards discloses an aspect or configuration that is essential to the present invention.

[0008] Aspect 1. The disclosed welding device includes a rotating shaft, a drive unit, a first reducer arranged coaxially with the rotating shaft, a second reducer arranged coaxially with the rotating shaft, a first welding gun, and a second welding gun. Rotational power is input to the rotating shaft. The drive unit is arranged coaxially with the rotating shaft and drives the rotating shaft to rotate. The first reducer has a first output unit through which the rotating shaft is inserted and rotatable around the rotating shaft, and a second output unit rotatable on one side of the rotating shaft in the axial direction relative to the first output unit. With the second output unit fixed so as not to rotate, the rotational power is reduced at a first reduction ratio and output to the first output unit, thereby rotating the outer circumferential surface of the first output unit in a direction opposite to the rotational direction of the rotating shaft. The second reducer has a third output portion, through which the rotary shaft is inserted and which is rotatable around the rotary shaft, on the other side of the first output portion in the axial direction, and a fourth output portion, which is rotatable on the other side of the third output portion, and with the third output portion fixed to the first output portion, reduces the rotational power at a second reduction ratio and outputs the reduced power to the fourth output portion, thereby rotating an outer circumferential surface of the fourth output portion. The first welding gun is attached to the outer circumferential surface of the first output portion. The second welding gun is attached to the outer circumferential surface of the fourth output portion.

[0009] Aspect 2. In the above aspect 1, it is preferable that the first reduction ratio is expressed by the following formula 1, and the second reduction ratio is expressed by the following formula 2. Note that a, b, and c are positive values ​​when the rotation direction is the same as the rotation direction of the rotation shaft, and are negative values ​​when the rotation direction is opposite to the rotation direction.

[0010] Aspect 3. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is different from the second reduction ratio. Aspect 4. In the above-mentioned Aspect 3, it is preferable that the first reduction ratio is half of the second reduction ratio.

[0011] Aspect 5. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is the same as the second reduction ratio. Aspect 6. In any one of the above-mentioned Aspects 1 to 5, it is preferable that the first welding gun is any one of an X-shaped welding gun, a C-shaped welding gun, and an indirect welding gun, and the second welding gun is any one of an X-shaped welding gun, a C-shaped welding gun, and an indirect welding gun.

[0012] Aspect 7. In any one of Aspects 1 to 6 above, it is preferable that one of the first welding gun and the second welding gun has a welding electrode, and the other has a ground electrode.

[0013] According to the disclosed welding device, the degree of freedom in layout of the welding device can be ensured.

[0014] 5 is an elevation view showing a robot arm to which a welding device according to an embodiment is applied, together with the welding device; FIG. 6 is a perspective view schematically showing a welding device according to an embodiment; FIG. 7 is a plan view schematically showing a state in which electrodes of a welding device according to an embodiment are closest to each other; FIG. 8 is a plan view schematically showing a state in which electrodes of a welding device according to an embodiment are furthest apart from each other; FIG. 9 is a perspective view schematically showing a rotation mechanism provided in a welding device according to an embodiment; FIG. 10 is a partially exploded perspective view of FIG. 11; FIG. 12 is a perspective view schematically showing a reducer alone used in a rotation mechanism provided in a welding device according to an embodiment; FIG. 13 is a schematic view showing an X welding gun used in a welding gun of a welding device according to an embodiment; FIG. 14 is a schematic view showing a C welding gun used in a welding gun of a welding device according to an embodiment; FIG. 15 is a schematic view showing an indirect welding gun used in a welding gun of a welding device according to an embodiment;

[0015] An embodiment of a welding device will be described with reference to the drawings. The welding device of this embodiment is a device that resistance-welds metal materials such as steel and aluminum using a pair of welding guns. Examples of workpieces (welding targets) that are welded by the welding device include metal members used in vehicles such as electric vehicles (EVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs). A plug-in hybrid vehicle is a hybrid vehicle that can externally charge or receive power from a battery. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility and a power outlet (outlet) for external power supply.

[0016] In the following embodiments, a Cartesian coordinate system having three mutually orthogonal coordinate axes, X, Y, and Z, is used as a reference for directions used in the description of the welding device. In this Cartesian coordinate system, the direction along the X axis is referred to as the "X direction" (a predetermined direction, a direction along the rotation axis of the rotation mechanism), the direction along the Y axis is referred to as the "Y direction," and the direction along the Z axis is referred to as the "Z direction."

[0017] The X direction has two inherent directions: the direction from negative to positive on the X axis and the direction from positive to negative on the X axis, which are opposite to each other. Therefore, one of the X directions will be referred to as the "X1 direction" and the other as the "X2 direction." Similarly, one of the Y directions will be referred to as the "Y1 direction" and the other as the "Y2 direction." One of the Z directions will be referred to as the "Z1 direction" and the other as the "Z2 direction."

[0018] The welding device exemplified in the following embodiment is formed symmetrically in the Y direction. However, the welding device does not have to be completely Y-symmetrical, and may be asymmetrical in the Y direction. Note that the expressions relating to directions such as "along," "along," and "extending along" used in this embodiment are not limited to directions parallel to a reference direction, but may also be slightly inclined relative to the reference direction.

[0019] [I. One Embodiment] [1. Configuration] Fig. 1 is an elevation view showing a robot arm to which a welding device according to one embodiment is applied. Fig. 2 is a perspective view schematically showing the welding device according to one embodiment. Fig. 3 is a plan view schematically showing a state in which electrodes of the welding device according to one embodiment are closest to each other. Fig. 4 is a plan view schematically showing a state in which electrodes of the welding device according to one embodiment are farthest from each other.

[0020] [1-1. Application Example of Welding Device] As shown in Fig. 1 , a welding device 1 according to this embodiment is attached to the tip 9a of a robot arm 9. The robot arm 9 is an industrial robot that changes the positions and postures of various devices attached to the tip 9a. The robot arm 9 illustrated in Fig. 1 is a vertical articulated robot that includes a plurality of arms 91, joints 92 for each arm 91, and actuators (not shown) built into the joints 92. The actuators built into the joints 92 are controlled by a controller (not shown), thereby controlling the welding device 1 attached to the tip 9a of the robot arm 9 to a position and posture suitable for welding.

[0021] 2, welding device 1 is provided with first welding gun 21 and second welding gun 22, a control unit 3, and a rotation mechanism 4 that changes the relative positions of the two welding guns 21, 22. The welding device 1 described here is provided with a support member 5 that supports a workpiece W (shown by a two-dot chain line in FIG. 2), and a device main body 6 to which various devices including support member 5 are attached.

[0022] Welding Guns 21 and 22 each have an electrode 1E, 2E (referred to as "E" when not otherwise distinguished) at the end (tip) in the X1 direction, an actuator 1A, 2A (referred to as "A" when not otherwise distinguished) at the end (base) in the X2 direction, and a main body 1B, 2B (referred to as "B" when not otherwise distinguished) between the electrode E and the actuator A in the X direction. The welding guns also have welding centers 1C, 2C (referred to as "C" when not otherwise distinguished) extending in the X direction. The electrodes E of the welding guns 21 and 22 are positioned so as to overlap with the respective welding centers C when viewed in the X direction (when viewed in the axial direction of a rotation shaft 4R, described later). Preferably, the centers of the electrodes E of the welding guns 21 and 22 and the respective welding centers C are positioned on the same line.

[0023] The electrode E extends in the X direction and is provided so as to be able to freely come into contact with a surface W1 of the workpiece W facing the X2 direction (hereinafter referred to as the "surface"). The actuator A is a drive source that urges the electrode E in the X1 direction. That is, the actuator A urges the electrode E against the surface W1 of the workpiece W. This actuator A is provided with a motor main body that generates an urging force that presses the electrode E against the surface W1 of the workpiece W, and an encoder for adjusting the amount of rotation of the motor main body (drive degree, rotation angle, rotation speed).

[0024] The main body B incorporates a mechanism (not shown) that transmits the biasing force of the motor main body of the actuator A to the electrode E. The main body B illustrated in FIG. 2 is cylindrical with a cylindrical axis along the X direction. Hereinafter, elements such as the electrode E and actuator A provided in the first welding gun 21 will be referred to with "first" in their element names and with "1" in their reference numerals. Furthermore, elements provided in the second welding gun 22 will be referred to with "second" in their element names and with "2" in their reference numerals. For example, the electrode E provided in the first welding gun 21 will be referred to as the "first electrode 1E," and the actuator A provided in the second welding gun 22 will be referred to as the "second actuator 2A."

[0025] ==Control Unit== The control unit 3 is a controller (electronic control device, control board, controller, etc.) that controls the actuators 1A, 2A that urge the electrodes 1E, 2E against the surface W1 of the workpiece W. Here, the magnitude of the force urging the first electrode 1E against the surface W1 of the workpiece W is referred to as the "first pressure force," and the magnitude of the force urging the second electrode 2E against the surface W1 of the workpiece W is referred to as the "second pressure force." The control unit 3 exemplified in this embodiment controls the first actuator 1A and the second actuator 2A in accordance with a preset profile so that the difference between the first pressure force and the second pressure force falls within a predetermined range. The "predetermined range" here includes a range in which the difference between the first pressure force and the second pressure force is not excessively large, an appropriate range determined by the properties of the workpiece W, etc.

[0026] ==Rotation Mechanism== The rotation mechanism 4 is a mechanism that rotates a first member 41 and a second member 42 (described later) in opposite directions and at the same speed. This rotation mechanism 4 has a rotating shaft 4R (shown by a dashed line in FIG. 2 ) to which rotational power is input from a driving unit 4S, and a reducer 40 that reduces the rotation of the rotating shaft 4R and outputs it. The driving unit 4S and the reducer 40 are arranged coaxially with an axial center 4C of the rotating shaft 4R in the welding device 1. This axial center 4C extends along the X direction. Therefore, the axial direction of the rotating shaft 4R can be said to be the X direction.

[0027] The drive unit 4S is not disposed on the outer periphery of the rotating shaft 4R, but is disposed in the extension direction of the axis 4C. Similar to the actuators 1A and 2A, the drive unit 4S is provided with a motor main body that generates rotational power and an encoder for adjusting the rotation amount (drive degree, rotation angle, rotation speed) of the motor main body. The reducer 40 is provided with a first member 41 and a second member 42 that output rotational power. The first member 41 and the second member 42 are annular members that rotate around the axis 4C. Note that any mechanism can be used for the reducer 40 as long as it rotates the first member 41 and the second member 42 in opposite directions and at the same speed.

[0028] The first member 41 and the second member 42 rotate around an axis 4C along the X direction, and therefore can be said to be members that rotate in a direction perpendicular to the X direction. Furthermore, when the rotation direction of the first member 41 and the second member 42 is used as a reference, the rotation axis 4R of the rotation mechanism 4 can be said to extend in a direction perpendicular to the rotation direction of the first member 41 and the second member 42.

[0029] When the drive unit 4S rotates the rotating shaft 4R in a first direction (e.g., counterclockwise when viewed from the X2 direction toward the X1 direction), the first member 41 rotates in the direction opposite to the first direction, and the second member 42 rotates in the first direction. Conversely, when the drive unit 4S rotates the rotating shaft 4R in a second direction (e.g., clockwise when viewed from the X2 direction toward the X1 direction), the first member 41 rotates in the direction opposite to the second direction (i.e., the above-mentioned first direction), and the second member 42 rotates in the second direction.

[0030] A first welding gun 21 is attached to the first member 41. Specifically, a first body portion 1B of the first welding gun 21 is fixed to the outer peripheral surface 4a of the first member 41. As a result, a first electrode 1E is fixed to the first member 41 via the first body portion 1B, and the position of the first electrode 1E is adjusted to a position corresponding to the rotational phase of the first member 41. A second welding gun 22 is attached to the second member 42. Specifically, a second body portion 2B of the second welding gun 22 is fixed to the outer peripheral surface 4b of the second member 42. As a result, a second electrode 2E is fixed to the second member 42 via the second body portion 2B, and the position of the second electrode 2E is adjusted to a position corresponding to the rotational phase of the second member 42.

[0031] When moving the welding guns 21, 22 away from each other, the drive unit 4S rotationally drives the rotating shaft 4R in a first direction, rotates the outer peripheral surface 4a of the first member 41 in a second direction, and rotates the outer peripheral surface 4b of the second member 42 in the first direction. When moving the welding guns 21, 22 closer to each other, the drive unit 4S rotationally drives the rotating shaft 4R in a second direction, rotates the outer peripheral surface 4a of the first member 41 in the first direction, and rotates the outer peripheral surface 4b of the second member 42 in the second direction. In this way, the relative positions of the welding guns 21, 22 are changed by the rotation mechanism 4, which rotates the first member 41 and the second member 42 in opposite directions but at the same speed.

[0032] The relative arrangement of the first electrode 1E and the second electrode 2E will be described below with reference to Figures 3 and 4. In the following description, the phase in which the outer peripheral surface 4a of the first member 41 has rotated the most in the first direction is referred to as the "first minimum phase," and the phase in which the outer peripheral surface 4b of the second member 42 has rotated the most in the second direction is referred to as the "second minimum phase." Furthermore, the phase in which the outer peripheral surface 4a of the first member 41 has rotated the most in the second direction is referred to as the "first maximum phase," and the phase in which the outer peripheral surface 4b of the second member 42 has rotated the most in the first direction is referred to as the "second maximum phase."

[0033] 3, when the rotation shaft 4R is rotated in the second direction, the outer peripheral surface 4a of the first member 41 has a first minimum phase, and the outer peripheral surface 4b of the second member 42 has a second minimum phase. The state in which the outer peripheral surfaces 4a, 4b have the minimum phase is the state in which the welding guns 21, 22 are closest to each other (hereinafter referred to as the "minimum pitch state"). In the minimum pitch state, as viewed in the X direction, a first midpoint M1 of a line segment S connecting the first welding center 1C and the second welding center 2C is located on the Z1 direction side of the shaft center 4C.

[0034] 4, when the rotation shaft 4R is rotated in the first direction, the outer peripheral surface 4a of the first member 41 assumes a first maximum phase, and the outer peripheral surface 4b of the second member 42 assumes a second maximum phase. The state in which the outer peripheral surfaces 4a, 4b assume the maximum phase is the state in which the welding guns 21, 22 are furthest apart (hereinafter referred to as the "maximum pitch state"). In the maximum pitch state, the second midpoint M2 of the line segment S coincides with the axis 4C as viewed in the X direction.

[0035] 3 and 4 , when viewed in the X direction, the line segment S extends along the Y direction, and the perpendicular bisector P of the line segment S extends along the Z direction. If the dimension by which the first electrode 1E is spaced in the Y1 direction from the perpendicular bisector P is defined as a first dimension L1, and the dimension by which the second electrode 2E is spaced in the Y2 direction from the perpendicular bisector P is defined as a second dimension L2, then regardless of whether the dimensions L1 and L2 are long or short, the first dimension L1 and the second dimension L2 are maintained equal to each other (L1 = L2, or, so to speak, "equal pitch").

[0036] Here, the illustrated perpendicular bisector P intersects with the axis 4C of the rotation shaft 4R. In particular, in the maximum pitch state illustrated in FIG. 4 , the axis 4C of the rotation shaft 4R extends in the Z direction through the intersection of the line segment S and the perpendicular bisector P. If we compare it to an analog clock with an hour hand centered on the axis 4C of the rotation shaft 4R and pointing in the Z1 direction indicating 12 o'clock, the first electrode 1E of the first minimum phase would be positioned at the 1 o'clock position, and the second electrode 2E of the second minimum phase would be positioned at the 11 o'clock position. Also, if we compare it to a similar analog clock, the first electrode 1E of the first maximum phase would be positioned at the 3 o'clock position, and the second electrode 2E of the second maximum phase would be positioned at the 9 o'clock position. If we compare it to the analog clock described above, the relative positions of the electrodes 1E and 2E will be changed as the first electrode 1E moves from either the 3 o'clock position or the 1 o'clock position to the other and the second electrode 2E moves from either the 9 o'clock position or the 11 o'clock position to the other.

[0037] A specific example of the rotation mechanism 4 will be described below with reference to FIGS. 5 to 7 . FIG. 5 is a perspective view schematically illustrating the rotation mechanism 4 provided in a welding device 1 according to an embodiment. FIG. 6 is a perspective view showing a portion of FIG. 5 exploded. FIG. 7 is a perspective view schematically illustrating each of the reducers 70 and 80 used in the rotation mechanism 4 provided in the welding device 1 according to an embodiment. As shown in FIGS. 5 and 6 , the rotation mechanism 4 illustrated here includes only one drive unit 4S (see FIG. 2 ) that rotationally drives the rotating shaft 4R, whereas two reducers 40, a first reducer 70 and a second reducer 80, are provided. The rotational power of the rotating shaft 4R is input to each of the reducers 70 and 80.

[0038] First, the configuration common to the reducers 70, 80 will be described with reference to Figure 7. The reducers 70, 80 are reducers in which the rotating shafts 41R, 42R (4R), cases 71, 81, and output flanges 72, 82 are arranged coaxially with one another. If the rotating shafts 41R, 42R are considered to be first elements, the cases 71, 81 are considered to be second elements, and the output flanges 72, 82 are considered to be third elements, the reducers 70, 80 can be said to be three-element, two-degree-of-freedom reducers. Here, a three-element, two-degree-of-freedom reducer means a reducer in which the rotational speed of the remaining element is uniquely determined when the rotational speeds of two of the three elements are determined.

[0039] The illustrated reducers 70 and 80 are high-precision control reducers that employ a planocentric reduction mechanism. A specific example of the reducers 70 and 80 is a so-called precision reducer RV. However, each reducer 70 and 80 may be a three-element, two-degree-of-freedom reducer consisting of at least three coaxially arranged elements, and a well-known planetary gear mechanism or harmonic reducer may be applied.

[0040] Each reducer 70, 80 is provided with a spur gear 7s, 8s that meshes with an input gear 4i provided on the outer periphery of the rotating shaft 4R, and each case 71, 81 and each output flange 72, 82 that are freely rotatable in accordance with the rotation of each spur gear 7s, 8s.

[0041] Specifically, the first reducer 70 includes a first spur gear 7s, a first case 71 (first output portion), and a first output flange 72 (second output portion). １ The second reducer 80 is provided with a second spur gear 8s, a second case 81 (third output portion), and a second output flange 82 (fourth output portion). The second reducer 80 has a second reduction ratio i ２ is set.

[0042] The rotary shaft 4R is inserted through the first case 71 and the second case 81, and the first case 71 and the second case 81 are rotatable about the rotary shaft 4R. The first output flange 72 is rotatable relative to the first case 71. Similarly, the second output flange 82 is rotatable relative to the second case 81.

[0043] The cases 71, 81 and the output flanges 72, 82 are coaxial with the axis 4C of the rotating shaft 4R and are provided in a cylindrical (annular) shape centered on the axis 4C. That is, the rotating shaft 4R is inserted through the cases 71, 81 and the output flanges 72, 82. This rotating shaft 4R has a first rotating shaft 41R, which is a portion that is inserted through the first case 71 and the first output flange 72 of the first reducer 70, and a second rotating shaft 42R, which is a portion that is inserted through the second case 81 and the second output flange 82 of the second reducer 80. The first rotating shaft 41R and the second rotating shaft 42R are connected to each other along the axis 4C and rotate together.

[0044] Each of the cases 71, 81 and each of the output flanges 72, 82 can output rotational power without being constrained by other elements, and can also be used by being attached to another fixed (immovable) member to prevent rotation, or by being constrained to rotate integrally with another rotating element. Therefore, the cases 71, 81 and the output flanges 72, 82 can output rotational power without being constrained by other elements, and can be used by being attached to another fixed (immovable) member to prevent rotation, or by being constrained to rotate integrally with another rotating element. １ , i ２ In other words, it is an element (output section) that can reduce the speed of the rotational power of the rotating shaft 4R and output it in accordance with the speed.

[0045] One common use of the reducers 70, 80 is to output rotational power to the output flanges 72, 82 in a state where the cases 71, 81 are fixed so as not to rotate. １ is defined as the value obtained by dividing the rotation speed of the first output flange 72 by the rotation speed of the first rotary shaft 41R when the first case 71 is fixed so as not to rotate. ２is defined as the value obtained by dividing the rotation speed of the second output flange 82 by the rotation speed of the second rotary shaft 42R when the second case 81 is fixed so as not to rotate.

[0046] The cases 71, 81 are case-shaped members that house the spur gears 7s, 8s on the shaft center 4C side (inside, so to speak). If the output flanges 72, 82 are fixed so as not to rotate, the reduction ratio i of the reducers 70, 80 can be adjusted. １ , i ２ The output flanges 72, 82 are arranged to rotate in the opposite direction to the rotation direction of the rotary shaft 4R regardless of the position of the output flanges 72, 82 in the X direction relative to the cases 71, 81. The output flanges 72, 82 can also be considered as members that protrude like a flange along the X direction. The output flanges 72, 82 that are not fixed so as to be non-rotatable are arranged to rotate in the direction opposite to the rotation direction of the rotary shaft 4R regardless of the position of the output flanges 72, 82 in the X direction relative to the cases 71, 81. １ , i ２ The direction of rotation is determined by

[0047] Next, the configuration of each of the reducers 70, 80 will be described with reference to Figures 5 and 6. In the reducer 40, the first output flange 72 and first case 71 of the first reducer 70 and the second case 81 and second output flange 82 of the second reducer 80 are arranged in this order from the X2 direction to the X1 direction. In other words, the first output flange 72 is located on the X2 direction side (one side) of the first case 71, the second case 81 is located on the X1 direction side (other side) of the first case 71, and the second output flange 82 is located on the X1 direction side (other side) of the second case 81.

[0048] 5, a connecting member 78 is provided between the first case 71 and the second case 81. The connecting member 78 is a member that connects the first case 71 and the second case 81 so that the first case 71 and the second case 81 rotate together, and is provided in a cylindrical shape that is coaxial with the axis 4C, just like the cases 71 and 81. However, the connecting member 78 may be omitted, and a reducer 40 in which the cases 71 and 81 are directly connected to each other may be used.

[0049] The first reducer 70 converts the rotational power of the rotary shaft 4R into a rotational power at a first reduction ratio i １ The first reducer 70, to which the rotational power is transmitted, is decelerated by a reduction ratio i １ , i ２ Regardless of the rotation direction, the outer peripheral surface 73 of the first case 71 is rotated in the direction opposite to the rotation direction of the rotary shaft 4R.

[0050] The second reducer 80 converts the rotational power of the rotating shaft 4R into a second reduction ratio i ２ The rotational speed is reduced by the first reduction ratio i １ In the second reducer 80, the rotational power of the first case 71 reduced by the reduction ratio i １ , i ２ The direction in which the outer peripheral surface 83 of the second output flange 82 is rotated is determined by the above.

[0051] Specifically, the first reduction ratio i of the first reducer 70 １ is expressed by the following equation 1, and the second reduction ratio i ２ is expressed by the following equation 2.

[0052]

[0053] The rotational speeds a, b, and c are positive when rotating in the same direction as the rotational direction of the rotary shaft 4R, and negative when rotating in the opposite direction to the rotational direction. The rotational speed a of the rotary shaft 4R is positive only, the rotational speed b of the first case 71 is negative only, and the rotational speed c of the second output flange 82 is determined by the reduction ratio i １ , i ２ It can take a positive or negative value depending on

[0054] In the first example of the reducer 40 described here, the first reduction ratio i １ and second reduction ratio i ２The "predetermined condition" here means a condition in which the rotation speed c of the second output flange 82 is a positive value and the absolute values ​​of the rotation speed c of the second output flange 82 and the rotation speed b of the first case 71 are equal to each other. In other words, the first reduction ratio i is set so as to satisfy the predetermined condition that the rotation speed c of the second output flange 82 and the rotation speed b of the first case 71 are the same speed but rotate in opposite directions to each other. １ and second reduction ratio i ２ Specifically, the relative magnitude relationship between the first reduction ratio i １ is the second reduction ratio i ２ is set to half of the

[0055] In the above-described reducers 70 and 80, the first case 71 is an example of the first member 41 in the rotation mechanism 4, and the second output flange 82 is an example of the second member 42 in the rotation mechanism 4. In this example, the outer peripheral surface 73 of the first case 71 corresponds to the outer peripheral surface 4a of the first member 41, and the outer peripheral surface 83 of the second output flange 82 corresponds to the outer peripheral surface 4b of the second member 42. １ and second reduction ratio i ２ The relative magnitude relationship of the first reduction ratio i １ is the second reduction ratio i ２ The setting is not limited to half of the above (the second setting in Table 1), and various other settings can be adopted.

[0056]

[0057] The first reduction ratio i １ is the second reduction ratio i ２ If the first reduction ratio i is less than the first setting, the second setting, the third setting, and the fifth setting, the second output flange 82 rotates in the opposite direction to the rotation direction of the first case 71. １ and the second reduction ratio i ２ If the rotational speeds are different, both the first case 71 and the second output flange 82 rotate.

[0058] First reduction ratio i １ is the second reduction ratio i ２If the first setting is less than half of the first reduction ratio i, the rotation speed c of the second output flange 82 will be faster than the rotation speed b of the first case 71 (|b|<|c|). １ is the second reduction ratio i ２ In the second setting, which is half of the above, the rotation speed b of the first case 71 and the rotation speed c of the second output flange 82 are equal (|b|=|c|), as described above.

[0059] First reduction ratio i １ is the second reduction ratio i ２ The second reduction ratio i is greater than half of ２ If the first reduction ratio i is set to a third setting less than the first reduction ratio i, the rotation speed b of the first case 71 will be faster than the rotation speed c of the second output flange 82 (|b|>|c|). １ and the second reduction ratio i ２ In the fourth setting where the first reduction ratio i is equal to the second reduction ratio i, the second output flange 82 does not rotate (c=0), and only the first case 71 rotates. １ The second reduction ratio i ２ If the fifth setting is greater than |b|, the second output flange 82 rotates in the same direction as the rotation direction of the first case 71, and the rotation speed c of the second output flange 82 is slower than the rotation speed b of the first case 71 (|b|>|c|).

[0060] ==Support Member== However, if the workpiece W is simply biased in the X1 direction by the two electrodes 1E, 2E, there is a risk that the workpiece W will move away in the X1 direction, making it impossible to ensure the pressure of the electrodes 1E, 2E on the workpiece W. Furthermore, even if the workpiece W is supported so as to be sandwiched only on the back side of the point where one of the two electrodes 1E, 2E abuts against the workpiece W, there is a risk that the pressure of the other of the two electrodes 1E, 2E will not be ensured.

[0061] Alternatively, if the workpiece W is supported so as to be sandwiched between the two electrodes 1E, 2E on the backside of the points where each of the electrodes 1E, 2E abuts against the workpiece W, the pressure applied by each of the electrodes 1E, 2E is ensured, but supporting members are required at two points on the backside of the workpiece W. If an attempt is made to provide members that support the workpiece W from the backside at two points corresponding to the positions of the two electrodes 1E, 2E in this way, the configuration becomes complicated, and depending on the shape and size of the workpiece W, the supporting members and the workpiece W may interfere with each other, which may restrict the shape and size of the workpiece W.

[0062] Therefore, in order to ensure a reaction force to the pressing force with a simple configuration, the welding device 1 of this embodiment is provided with a support member 5 that abuts against a surface W2 of the workpiece W facing the X1 direction (hereinafter referred to as the "back surface"). The support member 5 is provided so as to be able to abut against the back surface W2 of the workpiece W at least at one location on the perpendicular bisector P as viewed in the X direction. Fig. 2 illustrates an example in which the support member 5 is provided at only one location.

[0063] 3 and 4, the location of the support member 5 is preferably set in a region between the first midpoint M1 and the second midpoint M2 of the line segment S on the perpendicular bisector P, including the first midpoint M1 and the second midpoint M2, so that the support member 5 can easily resist the pressure of the electrodes 1E and 2E regardless of the positions of the electrodes 1E and 2E. It is more preferable that the location of the support member 5 (see FIG. 2) be midway between the first midpoint M1 and the second midpoint M2 on the perpendicular bisector P.

[0064] As shown in FIG. 2 , the support member 5 is a rod-shaped member bent toward the back surface W2 of the workpiece W. The illustrated support member 5 includes a first arm 51, a second arm 52, and a support electrode 5E. The first arm 51 is a portion extending in the X direction in a space spaced apart from the workpiece W in the Z2 direction. The second arm 52 is a portion on the X1 direction side of the workpiece W, extending from the Z2 direction end of the first arm 51 toward the Z1 direction. When the support member 5 is viewed from the Y1 direction, the first arm 51 and the second arm 52 form an L shape, and the X2 direction end of the first arm 51 is attached to the device main body 6, which will be described later. The support electrode 5E is an electrode protruding from the Z1 direction end of the second arm 52 toward the X2 direction.

[0065] The support member 5 is formed so as to embrace the workpiece W from the back side by the first arm portion 51, the second arm portion 52, and the support electrode 5E. The illustrated support electrode 5E is provided as an earth electrode. Meanwhile, the first electrode 1E and the second electrode 2E are provided as welding electrodes. In resistance welding using the welding device 1, the portion where the support electrode 5E provided as an earth electrode abuts on the workpiece W is not welded, but the portion where the electrodes 1E, 2E provided as welding electrodes abut on the workpiece W is welded.

[0066] Specifically, electrodes 1E, 2E, and 5E are brought into contact with the workpiece W and a current is passed through them, and the electrodes 1E and 2E provided as welding electrodes on the workpiece W melt due to resistance heat at the points where they are in contact with the workpiece W, thereby welding the melted points. For this reason, it is desirable to suppress the contact resistance of the support electrode 5E provided as an earth electrode and suppress heat generation at the points where the support electrode 5E is in contact.

[0067] From this perspective, in the welding apparatus 1 of this embodiment, two electrodes 1E, 2E provided as welding electrodes are brought into contact with the front surface W1 of the workpiece W with a first pressure force and a second pressure force, while one support electrode 5E provided as an earth electrode is brought into contact with the back surface W2 of the workpiece W with a pressure force that is the sum of the first pressure force and the second pressure force, thereby supporting the workpiece W in a balanced manner. This balance of pressure forces suppresses the contact resistance of the support electrode 5E provided as an earth electrode, thereby suppressing resistance heating at the contact points of the support electrode 5E. Furthermore, resistance heating at the contact points of the electrodes 1E, 2E provided as welding electrodes is ensured.

[0068] Note that the support member 5 does not necessarily have to be provided with a support electrode 5E. A support member 5 not provided with a support electrode 5E is provided with a member protruding in the X2 direction from the Z1-direction end of the second arm 52 instead of the support electrode 5E. In this case, it is preferable that one of the first electrode 1E and the second electrode 2E is a welding electrode and the other is a ground electrode. That is, it is preferable that one of the first welding gun 21 and the second welding gun 22 has a welding electrode and the other has a ground electrode.

[0069] ==Device Main Body== The support member 5 is detachably held in the device main body 6. By replacing the attached support member 5 with another support member 5 of a different shape or size, it is possible to attach various support members 5 to the device main body 6. The rotation mechanism 4 is attached to this device main body 6, and various devices and components may also be attached, including a transformer that changes and outputs voltage to the drive unit 4S of the rotation mechanism 4 and the actuators 1A, 2A of the welding guns 21, 22.

[0070] Since the device main body 6 and the devices and members attached to the device main body 6 are fixed (immovable), they are set at fixed locations that non-rotatably restrain the first output flange 72. For example, the first output flange 72 is fixed to a transformer attached to the device main body 6.

[0071] ==Other== Various known welding guns can be used for welding guns 21, 22. For example, any of an X welding gun (also called an "X gun"), a C welding gun (also called a "C gun"), and an indirect welding gun can be used for first welding gun 21. Furthermore, any of an X welding gun, a C welding gun, and an indirect welding gun can be used for second welding gun 22.

[0072] An X-shaped welding gun is a welding gun that has an X-shape or a partial X-shape when viewed from a direction perpendicular to the X direction and is provided so that it can swing freely like scissors. When X-shaped welding guns are used for welding guns 21 and 22, welding guns 21 and 22 are provided at least in part of the X-shape or partial X-shape of the X-shaped welding gun.

[0073] 8 , which shows an example in which an X-welding gun is used as the second welding gun 22 as viewed in the Y direction (from a perspective perpendicular to the X direction), the support member 5, device body 6, and second welding gun 22 form at least a portion of an X-shape. If the X-shape that forms the general shape of the X-welding gun is considered to be the shape of two intersecting lines, the support member 5 is provided at a first portion 10 corresponding to one of the lines, and the device body 6 and second welding gun 22 are provided at a second portion 20 corresponding to the other line.

[0074] This X welding gun is provided with a shaft 12 that supports a first portion 10 and a second portion 20 so that they can swing relative to each other. The X welding gun illustrated in Fig. 8 is provided with an actuator A that swings the second portion 20 relative to the first portion 10. This actuator A swings the second portion 20 around the shaft 12 by moving the second portion 20 toward and away from the first portion 10.

[0075] As described above, the two welding guns 21, 22 are attached to the device body 6 via the rotation mechanism 4. Therefore, the actuator A that swings the second portion 20 on which the device body 6 is provided is a single actuator A that also functions as the first actuator 1A and the second actuator 2A described above.

[0076] A C-shaped welding gun is a welding gun whose general shape is C-shaped when viewed from a direction perpendicular to the X direction. When C-shaped welding guns 21 and 22 are used, the welding guns 21 and 22 are provided at least partially on the general shape of the C-shaped welding gun. Referring to FIG. 9 , which shows an example in which a C-shaped welding gun is used as the first welding gun 21 as viewed from the Y direction (perspective perpendicular to the X direction), the general shape of the support member 5, the device body 6, and the first welding gun 21 forms a C-shaped general shape. Specifically, from one end of the C-shape to the other end as viewed from the Y direction, the first electrode 1E and first body 1B of the first welding gun 21, the device body 6, the first arm 51, the second arm 52, and the support electrode 5E are arranged in this order. A first actuator 1A protrudes from the first body 1B in the X2 direction.

[0077] An indirect welding gun is a welding gun in which a welding electrode is provided only on the X1 direction side or the X2 direction side (i.e., only one side) of the workpiece W. When an indirect welding gun is used for welding guns 21, 22, a welding electrode is provided on each of electrodes 1E, 2E of welding guns 21, 22, and a ground electrode is provided on support electrode 5E of support member 5. In other words, if a ground electrode is provided on support electrode 5E and a welding electrode is provided on each of electrodes 1E, 2E of welding guns 21, 22, it can be said that an indirect welding gun is used for welding guns 21, 22.

[0078] 10 , which shows an example in which indirect welding guns are used as the welding guns 21, 22 as viewed in the Z direction (from a perspective perpendicular to the X direction), a welding electrode is provided on each of electrodes 1E, 2E of welding guns 21, 22 that contacts the front surface W1 of the workpiece W. Furthermore, of the support electrode 5E formed by the first arm 51, the second arm 52, and the support electrode 5E so as to embrace the workpiece W from the back side, a ground electrode is provided on the support electrode 5E that contacts the back surface W2 of the workpiece W.

[0079] [2. Actions and Effects] The welding device 1 of this embodiment is configured as described above, and therefore has the following actions and effects. (1) According to the welding device 1 of this embodiment, the provision of the first reducer 70 and the second reducer 80 allows the relative positioning of the first welding gun 21 and the second welding gun 22 to be changed. Furthermore, because the drive unit 4S is arranged coaxially with the rotation shaft 4R, the drive unit 4S is less likely to interfere with other components, such as the workpiece W and welding guns 21 and 22, that are arranged around the rotation shaft 4R, and this ensures flexibility in the layout of the welding device 1.

[0080] (2) The reduction ratio i of the reducers 70 and 80 is expressed by the above formulas 1 and 2. １ , i ２ By setting the first reduction ratio i as shown in the first setting, the second setting, the third setting, and the fifth setting in Table 1 above, the welding guns 21 and 22 can be moved relatively closer to and away from each other in various ways. １ and the second reduction ratio i ２ If the positions are different, the positions of both the first welding gun 21 and the second welding gun 22 can be changed. This increases the degree of freedom in dealing with various welding locations.

[0081] (4) The first reduction ratio i as shown in Table 1 above １ is the second reduction ratio i ２ , the first welding gun 21 and the second welding gun 22 can be moved in opposite directions at the same speed. １ and the second reduction ratio i ２If these are the same, the first welding gun 21 can be moved while the position of the second welding gun 22 is fixed.

[0082] (6) Either an X-shaped welding gun, a C-shaped welding gun, or an indirect welding gun is used for each of the welding guns 21, 22. Therefore, using an appropriate welding gun 21, 22 from among an X-shaped welding gun, a C-shaped welding gun, or an indirect welding gun depending on the shape, type, size, etc. of the workpiece W contributes to good welding of the workpiece W. (7) If either the first welding gun 21 or the second welding gun 22 has a welding electrode and the other has a ground electrode, welding can be performed at a single location where the welding electrode abuts the workpiece W. In other words, welding can be performed at a single location where the welding electrode abuts the workpiece W (so-called "indirect spot welding").

[0083] [II. Modifications] The above-described embodiment is merely an example, and is not intended to exclude various modifications and application of techniques not explicitly described in this embodiment. Each configuration of this embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, the configurations can be selected and combined as needed.

[0084] The welding device 1 of this embodiment may include at least the rotating shaft 4R, the driving unit 4S, the reducers 70 and 80, and the welding guns 21 and 22. In one embodiment, the reducers 70 and 80 have a reduction ratio i １ , i ２ is set, other forms may also be employed.

[0085] Support member 5 is not limited to being detachably held by device body 6, but may be fixed to device body 6. Control unit 3 of welding guns 21, 22 is not limited to being configured to control actuators 1A, 2A according to a preset profile so that the difference between the first and second pressurizing forces falls within a predetermined range, but may be configured in any manner. Alternatively, control unit 3 of welding guns 21, 22 may be omitted from welding device 1.

[0086] The support member 5 is not limited to a rod-shaped member that bends toward the back surface W2 of the workpiece W as described above in the embodiment, and various other members can be used as long as they can freely come into contact with the back surface W2 of the workpiece W. Furthermore, the support member 5 may be configured to be able to come into contact with the back surface W2 of the workpiece W at two or more locations on the perpendicular bisector P as viewed in the X direction, or multiple support members 5 may be provided so as to be able to come into contact with the back surface W2 of the workpiece W at two or more locations.

[0087] The present invention is applicable to manufacturing industries that use welding equipment.

[0088] DESCRIPTION OF SYMBOLS 1 Welding device 1A First actuator 1E First electrode 2A Second actuator 2E Second electrode 21 First welding gun 22 Second welding gun 3 Control unit 4 Rotation mechanism 41 First member 42 Second member 4R Rotation shaft 4S Drive unit 5 Support member 5E Support electrode 6 Device body 70 First reducer 71 First case (first output part, first member) 72 First output flange (second output part) 73 Outer circumferential surface 80 Second reducer 81 Second case (third output part) 82 Second output flange (fourth output part, second member) 83 Outer circumferential surface a Rotational speed of rotating shaft b Rotational speed of first case c Rotational speed of second output flange i １ First reduction ratio i ２ Second reduction ratio P Perpendicular bisector S Line segment W Workpiece W1 Front surface W2 Back surface

Claims

1. A rotating shaft into which rotational power is input, a drive unit arranged coaxially with the rotating shaft and configured to drive the rotating shaft to rotate, a first reducer arranged coaxially with the rotating shaft, the first reducer having a first output unit through which the rotating shaft is inserted and configured to be rotatable around the rotating shaft, and a second output unit rotatable on one axial side of the rotating shaft relative to the first output unit, wherein, with the second output unit fixed so as not to rotate, the rotational power is reduced at a first reduction ratio and output to the first output unit, thereby rotating the outer circumferential surface of the first output unit in a direction opposite to the rotation direction of the rotating shaft, and a second reducer arranged coaxially with the rotating shaft, the second reducer having a third output unit through which the rotating shaft is inserted on the other axial side of the first output unit and configured to be rotatable around the rotating shaft, and a fourth output unit rotatable on the other side of the third output unit, wherein, with the third output unit fixed to the first output unit, the rotational power is reduced at a second reduction ratio and output to the fourth output unit, thereby rotating the outer circumferential surface of the fourth output unit. A welding device comprising: a first welding gun attached to the outer peripheral surface of the first output portion; and a second welding gun attached to the outer peripheral surface of the fourth output portion.

2. The welding device according to claim 1, wherein the first reduction ratio is expressed by the following formula 1, and the second reduction ratio is expressed by the following formula 2. Note that a, b, and c are positive values ​​when the rotation direction is the same as the rotation direction of the rotation shaft, and are negative values ​​when the rotation direction is opposite to the rotation direction.

3. The welding device according to claim 2, wherein the first reduction ratio is different from the second reduction ratio.

4. The welding device according to claim 3, wherein the first reduction ratio is half the second reduction ratio.

5. The welding device according to claim 2, wherein the first reduction ratio is the same as the second reduction ratio.

6. The welding device according to claim 1 or 2, wherein the first welding gun is one of an X-type welding gun, a C-type welding gun, and an indirect welding gun, and the second welding gun is one of an X-type welding gun, a C-type welding gun, and an indirect welding gun.

7. The welding device according to claim 1 or 2, wherein one of the first welding gun and the second welding gun has a welding electrode, and the other has a ground electrode.

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