Rotary unit

Abstract

To provide a rotary unit which can be reduced in diametrical size and can rotate a plurality of rotors with one driving source.SOLUTION: A rotary unit comprises: a main shaft part; a driving source; a first rotor rotating in a first direction; a second rotor rotating in a second direction; a support part; a first gear fitted to the first rotor; a second gear which is meshed with the first gear and rotates in the second direction; a third gear arranged at intervals from the second gear in an axial direction and rotates together with the second gear in the second direction; a fourth gear meshed with the third gear and rotating in the first direction; a fifth gear arranged at intervals from the fourth gear in the axial direction and rotating in the first direction together with the fourth gear; and a sixth gear which is fitted to the second rotor, is meshed with the fifth gear, and rotates around a central axis of the main shaft part together with the second rotor in the second direction. Each of the first gear, the second gear, the third gear, the fourth gear, the fifth gear and the sixth gear is disposed between the first rotor and the second rotor in the axial direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a rotary unit. [Background technology]

[0002] A method for controlling the operation of a workpiece gripping hand is known, which includes a pair of rack gears facing each other with a pinion gear sandwiched therebetween and a pair of gripping fingers formed integrally with each of the pair of rack gears, and which rotates the pinion gear forward and backward to open and close the pair of gripping fingers (see, for example, Patent Document 1).The method for controlling the operation of a workpiece gripping hand disclosed in Patent Document 1 moves the pair of gripping fingers toward or away from each other from a standby position, thereby repeatedly gripping a workpiece between the pair of gripping fingers or outside the pair of gripping fingers, and changes the standby position to change the meshing position of the teeth of the pair of rack gears and pinion gear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-214472 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 uses one motor to transmit power to two movable bodies, and requires gears to be arranged radially relative to the motor shaft. This configuration results in a large radial size, which may not meet the needs of users. There is a demand for a rotary unit that rotates multiple rotating bodies with one drive source, with a smaller radial size.

[0005] Therefore, one object is to provide a rotation unit that can rotate a plurality of rotating bodies with one driving source and can achieve a reduction in size in the radial direction. [Means for solving the problem]

[0006] A rotation unit according to the present disclosure includes a main shaft portion, a drive source for rotating the main shaft portion, a first rotor attached to the main shaft portion and rotating in a first direction around the central axis of the main shaft portion as a rotation center due to the rotation of the main shaft portion, a second rotor arranged in parallel to the first rotor at an axial distance from the first rotor and rotating in a second direction opposite to the first direction around the central axis of the main shaft portion as a rotation center due to the rotation of the main shaft portion, a support portion for rotatably supporting the first rotor and the second rotor, and a support portion attached to the first rotor and rotating together with the first rotor around the central axis of the main shaft portion. The gearbox includes a first gear that rotates in a first direction around the center of rotation, a second gear that meshes with the first gear and rotates in a second direction, a third gear that is spaced apart from the second gear in the axial direction and rotates together with the second gear in the second direction, a fourth gear that meshes with the third gear and rotates in the first direction, a fifth gear that is spaced apart from the fourth gear in the axial direction and rotates together with the fourth gear in the first direction, and a sixth gear that is attached to the second rotor, meshes with the fifth gear, and rotates together with the second rotor in the second direction around the central axis of the main shaft. The first gear, second gear, third gear, fourth gear, fifth gear, and sixth gear are each located axially between the first rotor and the second rotor. [Effects of the Invention]

[0007] According to the above-described rotation unit, a plurality of rotating bodies can be rotated by one driving source, and the size in the radial direction can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view showing a rotation unit for a spot welding gun including a rotation unit according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic front view of the spot welding gun rotation unit shown in FIG. [Figure 3] FIG. 3 is a schematic plan view of the spot welding gun rotation unit shown in FIG. [Figure 4]FIG. 4 is a schematic side view of the spot welding gun rotation unit shown in FIG. [Figure 5] FIG. 5 is a schematic perspective view of the rotation unit according to the first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view of the rotary unit shown in FIG. [Figure 7] FIG. 7 is a schematic diagram showing the rotational movement of the first rotating body and the second rotating body. [Figure 8] FIG. 8 is a simplified schematic diagram showing a part of the rotation unit for a spot welding gun as viewed in the direction opposite to the direction indicated by the arrow Z. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Outline of the embodiment] The rotation unit of the present disclosure includes a main shaft portion, a drive source for rotating the main shaft portion, a first rotor attached to the main shaft portion and rotating in a first direction around the central axis of the main shaft portion as a rotation center due to the rotation of the main shaft portion, a second rotor arranged in parallel to the first rotor at an axial distance from the first rotor and rotating in a second direction opposite to the first direction around the central axis of the main shaft portion as a rotation center due to the rotation of the main shaft portion, a support portion for rotatably supporting the first rotor and the second rotor, and a support portion attached to the first rotor and rotating around the central axis of the main shaft portion together with the first rotor. The rotating gear includes a first gear that rotates in a first direction around a rotation center, a second gear that meshes with the first gear and rotates in a second direction, a third gear that is spaced apart from the second gear in the axial direction and rotates together with the second gear in the second direction, a fourth gear that meshes with the third gear and rotates in the first direction, a fifth gear that is spaced apart from the fourth gear in the axial direction and rotates together with the fourth gear in the first direction, and a sixth gear that is attached to the second rotating body, meshes with the fifth gear, and rotates together with the second rotating body in the second direction around the central axis of the main shaft. The first gear, second gear, third gear, fourth gear, fifth gear, and sixth gear are each located axially between the first rotating body and the second rotating body.

[0010] According to the rotation unit of the present disclosure, when the main shaft portion is rotated by the drive source, the first rotor attached to the main shaft portion rotates together with the main shaft portion in a first direction around the central axis of the main shaft portion. Furthermore, when the first rotor rotates in the first direction via the first gear, second gear, third gear, fourth gear, fifth gear, and sixth gear, the second rotor rotates in a second direction, which is the opposite direction to the first direction, around the central axis of the main shaft portion. In this case, the first gear, second gear, third gear, fourth gear, fifth gear, and sixth gear are each disposed between the first rotor and the second rotor in the axial direction, thereby preventing the radial size from increasing. As described above, the rotation unit can rotate multiple rotors with a single drive source, thereby achieving a compact radial size.

[0011] The rotating unit may further include a bearing that includes a rolling element and rotatably supports at least one of the first rotating element and the second rotating element. In this way, the bearing includes the rolling element, thereby ensuring smoother rotational movement of the rotating element supported by the bearing.

[0012] In the above-described rotary unit, at least one of the first rotary body and the second rotary body may include a protruding portion that protrudes part of its circumferential portion toward the outer diameter side. By doing so, it is possible to easily attach a rotating member to the rotary body using this protruding portion. Therefore, convenience can be improved.

[0013] In the rotation unit, the drive source may be provided at an axial end of the main shaft, which simplifies the configuration for rotating the main shaft with the drive source and makes the radial size more compact.

[0014] In the above-described rotary unit, the second rotary body may have the same shape as the first rotary body, which allows the use of a common member as the rotary body, thereby improving productivity.

[0015] The rotation unit may further include a first shaft and a second shaft, each rotatably supported by a support. The second gear and the third gear may be coaxially fixed by the first shaft. The fourth gear and the fifth gear may be coaxially fixed by the second shaft. This allows the second gear and the third gear to be easily rotated in the same direction by the first shaft, and the fourth gear and the fifth gear to be easily rotated in the same direction by the second shaft. Therefore, the configuration of each component can be simplified while the device configuration can be made more compact.

[0016] In the above rotating unit, the second gear may have the same shape as the fifth gear. The third gear may have the same shape as the fourth gear. By doing so, some of the multiple gears can be used as common components, thereby improving productivity.

[0017] In the rotating unit, at least one of the first rotating body and the second rotating body may have a hollow cylindrical portion, thereby reducing the material cost of the members constituting the rotating body and reducing the weight of the rotating unit.

[0018] In the rotation unit, the drive source may include a servo motor. Such a drive source is preferably used because it can be used in harsh environments and can properly reverse the direction of rotation.

[0019] [Specific example of embodiment] Next, an example of a specific embodiment of the rotary unit of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0020] (Embodiment 1) First, a first embodiment of the present disclosure will be described. FIG. 1 is a schematic perspective view of a spot welding gun rotation unit including a rotation unit according to the first embodiment of the present disclosure. FIG. 2 is a schematic front view of the spot welding gun rotation unit shown in FIG. 1. FIG. 2 is a view from the direction indicated by arrow II in FIG. 1. FIG. 3 is a schematic plan view of the spot welding gun rotation unit shown in FIG. 1. FIG. 3 is a view from the direction indicated by arrow III in FIG. 1. FIG. 4 is a schematic side view of the spot welding gun rotation unit shown in FIG. 1. FIG. 4 is a view from the direction indicated by arrow IV in FIG. 1. FIG. 5 is a schematic perspective view of the rotation unit according to the first embodiment. That is, FIG. 5 is a view showing a state in which a pair of spot welding guns, which will be described later, has been removed from the spot welding gun rotation unit shown in FIG. 1. FIG. 6 is a schematic cross-sectional view of the rotation unit shown in FIG. 5. FIG. 6 is a schematic cross-sectional view taken along the line indicated by arrows VI-VI in FIG. 5. 1 and the following figures, the X direction indicates the width direction of the spot welding gun rotation unit, the Y direction indicates the front-to-rear direction of the spot welding gun rotation unit, and the Z direction indicates the up-down direction, which is the height direction of the spot welding gun rotation unit. The X direction, Y direction, and Z direction are perpendicular to each other. In FIG. 6, the central axis 20a, which is the rotation center of the main shaft portion described later, is indicated by a dashed line.

[0021] 1, 2, 3, 4, 5, and 6, spot welding gun rotation unit 10a including rotation unit 11a according to the first embodiment of the present disclosure includes a plurality of spot welding guns, specifically a pair of spot welding guns (first spot welding gun 12a and second spot welding gun 13a). That is, spot welding gun rotation unit 10a is provided with first spot welding gun 12a and second spot welding gun 13a. Spot welding gun rotation unit 10a is effectively used, for example, when performing spot welding. Spot welding gun rotation unit 10a is installed so that the top-bottom direction is the up-down direction, as shown in FIG. 1. Note that, for example, servo guns that perform welding by driving servo motors are used as first spot welding gun 12a and second spot welding gun 13a.

[0022] First spot welding gun 12a and second spot welding gun 13a are each attached to rotary unit 11a. First spot welding gun 12a includes a first arm portion 14a for attachment to rotary unit 11a, a first holder portion 15a connected to first arm portion 14a, and a first electrode portion 16a extending from first holder portion 15a in a direction opposite to the direction indicated by arrow Z. During spot welding, first electrode portion 16a irradiates a laser or the like vertically downward. Like first spot welding gun 12a, second spot welding gun 13a also includes a second arm portion 17a, a second holder portion 18a, and a second electrode portion 19a.

[0023] Next, the configuration of the rotation unit 11a will be described. The rotation unit 11a includes a main shaft portion 21a, a servo motor 22a as a drive source, a first rotor 23a, a second rotor 24a, and a support portion 25a. The main shaft portion 21a is solid cylindrical. The servo motor 22a is provided at the axial end of the main shaft portion 21a, specifically, at the upper end of the main shaft portion 21a. The support portion 25a also functions as a housing for the entire rotation unit 11a. The support portion 25a includes a first portion 26a, a second portion 27a, a third portion 28a, a fourth portion 29a, and a base portion 30a. A first window 59a that penetrates the first portion 26a in the radial direction is provided in a region where a first protrusion 45a (described later) can rotate. Similarly, the second portion 27a has a second window 60a that penetrates radially in an area where a second protrusion 46a (described later) can rotate. The base portion 30a is plate-shaped, and the parts that make up the rotation unit 11a are arranged on the base portion 30a. The first portion 26a, the second portion 27a, the third portion 28a, and the fourth portion 29a are arranged at intervals in the axial direction (Z direction).

[0024] The rotation unit 11a includes multiple bearings, a total of four in this embodiment (first bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a). The first bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a are arranged at intervals in the axial direction (Z direction). Specifically, the bearings are arranged in the order of first bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a from the position closest to the servo motor 22a. That is, the bearing closest to the base portion 30a is the fourth bearing 34a. The first bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a each include rollers (first roller 35a, second roller 36a, third roller 37a, and fourth roller 38a) as rolling elements. The rolling elements may be balls.

[0025] Driven by servo motor 22a, main shaft portion 21a rotates in a first direction indicated by arrow R1 in Fig. 6 and in a second direction indicated by arrow R2 in Fig. 6. The second direction is the opposite direction to the first direction. That is, servo motor 22a can switch the rotation direction of main shaft portion 21a between forward and reverse.

[0026] First rotor 23a rotates in a first direction around central axis 20a of main shaft 21a as a result of rotation of main shaft 21a. First rotor 23a is rotatably supported by support 25a. Specifically, first rotor 23a is rotatably supported by first bearing 31a and second bearing 32a at first portion 26a of support 25a. First rotor 23a includes a first side plate 41a and a second side plate 42a located at opposite ends in the axial direction. In the axial direction, first side plate 41a is located on the servo motor 22a side, and second side plate 42a is located on the base portion 30a side. First side plate 41a is attached to main shaft 21a via various members. The first bearing 31a is attached to the first rotating body 23a on the side of the first side plate 41a, and the second bearing 32a is attached to the first rotating body 23a on the side of the second side plate 42a. The first rotating body 23a includes a protruding portion (first protruding portion 45a) that protrudes radially outward from a portion of its circumferential surface. The first protruding portion 45a is connected to the first arm portion 14a of the first spot welding gun 12a. The first rotating body 23a also has a first gap portion 57a ​​that is a hollow cylindrical portion.

[0027] The second rotating body 24a rotates in a second direction, which is opposite to the first direction, around the central axis 20a of the main shaft 21a as a rotation center due to the rotation of the main shaft 21a. The second rotating body 24a is rotatably supported by the support 25a. Specifically, the second rotating body 24a is rotatably supported by a third bearing 33a and a fourth bearing 34a at a second portion 27a of the support 25a. The second rotating body 24a includes a third side plate 43a and a fourth side plate 44a located at opposite ends in the axial direction. In the axial direction, the third side plate 43a is located on the servo motor 22a side, and the fourth side plate 44a is located on the base 30a side. In other words, the second side plate 42a of the first rotating body 23a and the third side plate 43a of the second rotating body 24a face each other with an axial gap between them. The third bearing 33a is attached to the second rotating body 24a on the third side plate 43a side, and the fourth bearing 34a is attached to the second rotating body 24a on the fourth side plate 44a side. The second rotating body 24a also includes a protruding portion (second protruding portion 46a) that protrudes radially outward from a portion of its circumferential surface.

[0028] The second rotating body 24a has the same shape as the first rotating body 23a. The second rotating body 24a is attached so that the circumferential position of the second protrusion 46a of the second rotating body 24a is different from the circumferential position of the first protrusion 45a of the first rotating body 23a. The second protrusion 46a is connected to the second arm 17a of the second spot welding gun 13a. The second rotating body 24a also has a second gap 58a, which is a hollow cylindrical portion.

[0029] Here, the rotation unit 11a includes a plurality of gears, specifically, a first gear 51a, a second gear 52a, a third gear 53a, a fourth gear 54a, a fifth gear 55a, and a sixth gear 56a. The six gears, i.e., the first gear 51a, the second gear 52a, the third gear 53a, the fourth gear 54a, the fifth gear 55a, and the sixth gear 56a, are respectively arranged axially between the first rotor 23a and the second rotor 24a. Specifically, the first gear 51a, the second gear 52a, the third gear 53a, the fourth gear 54a, the fifth gear 55a, and the sixth gear 56a are arranged axially between the second side plate 42a of the first rotor 23a and the third side plate 43a of the second rotor 24a. The first gear 51a, the second gear 52a, the fifth gear 55a, and the sixth gear 56a all have the same number of external teeth. The second gear 52a has the same shape as the fifth gear 55a. The third gear 53a and the fourth gear 54a also have the same number of external teeth. The third gear 53a has the same shape as the fourth gear 54a. The gear ratio of the third gear 53a to the first gear 51a is 2.

[0030] The first gear 51a is attached to the second side plate 42a so as to rotate about the central axis 20a of the main shaft portion 21a. The second gear 52a meshes with the first gear 51a and rotates in a second direction that is opposite to the first direction.

[0031] The rotation unit 11a includes a first shaft 47a rotatably supported by the support 25a. The first shaft 47a is rotatably supported by a third portion 28a of the support 25a. The second gear 52a and the third gear 53a are fixed coaxially to the first shaft 47a, which extends in the axial direction. The second gear 52a and the third gear 53a rotate in the same direction around a central axis 48a, which extends in the axial direction of the first shaft 47a. That is, the third gear 53a rotates in the second direction together with the second gear 52a.

[0032] The fourth gear 54a meshes with the third gear 53a and rotates in the first direction. The fourth gear 54a and the fifth gear 55a are fixed coaxially to a second shaft portion 49a that extends in the axial direction.

[0033] The rotation unit 11a includes a second shaft portion 49a rotatably supported by the support portion 25a. The second shaft portion 49a is rotatably supported by a fourth portion 29a of the support portion 25a. The fourth gear 54a and the fifth gear 55a rotate in the same direction around a central axis 50a extending in the axial direction of the second shaft portion 49a. That is, the fifth gear 55a rotates in the first direction together with the fourth gear 54a. The second shaft portion 49a is rotatably supported by the fourth portion 29a of the support portion 25a.

[0034] The sixth gear 56a is attached to the third side plate 43a so as to rotate around the central axis 20a of the main shaft portion 21a. The sixth gear 56a meshes with the fifth gear 55a and rotates in a second direction, which is the opposite direction to the first direction. Because the sixth gear 56a is attached to the third side plate 43a of the second rotating body 24a, the second rotating body 24a rotates in the second direction together with the sixth gear 56a.

[0035] Next, the rotational movement of the first rotor 23a and the second rotor 24a will be described. FIG. 7 is a schematic diagram showing the rotational movement of the first rotor 23a and the second rotor 24a. Also referring to FIG. 7, first, when the servo motor 22a rotates the main shaft 21a in a first direction (the direction indicated by the arrow R1), the first rotor 23a attached to the main shaft 21a rotates in the first direction. Then, the first gear 51a attached to the first rotor 23a rotates in the first direction together with the first rotor 23a. Because the second gear 52a is engaged with the first gear 51a, the second gear 52a rotates in the second direction (the direction indicated by the arrow R2). At this time, the second gear 52a rotates around the central axis 48a of the first shaft 47a. Because the second gear 52a and the third gear 53a are coaxially fixed to the first shaft portion 47a extending in the axial direction, the third gear 53a also rotates in the second direction. Because the fourth gear 54a is meshed with the third gear 53a, it rotates in a first direction (the direction indicated by arrow R1), which is the opposite direction to the second direction. That is, the rotation direction of the first rotor 23a and the first gear 51a is the same as the rotation direction of the fourth gear 54a. At this time, the fourth gear 54a rotates around the central axis 50a of the second shaft portion 49a. Because the fourth gear 54a and the fifth gear 55a are coaxially fixed by the second shaft portion 49a, the fifth gear 55a also rotates in the first direction. The sixth gear 56a is engaged with the fifth gear 55a and therefore rotates in a second direction (the direction indicated by the arrow R2), which is the opposite direction to the first direction. The sixth gear 56a is attached to the second rotating body 24a, and therefore the second rotating body 24a rotates in the second direction together with the sixth gear 56a. In this way, the servo motor 22a is used as a drive source to rotate the first rotating body 23a and the second rotating body 24a in opposite directions. In this case, the first rotating body 23a and the second rotating body 24a rotate at the same speed, i.e., at the same velocity. Furthermore, the first rotating body 23a and the second rotating body 24a rotate at the same pitch.

[0036] In the spot welding gun rotation unit 10a described above, first protrusion 45a of first rotor 23a and first arm 14a of first spot welding gun 12a are connected, so first spot welding gun 12a also rotates in the first direction together with first rotor 23a. Furthermore, second protrusion 46a of second rotor 24a and second arm 17 of second spot welding gun 13a are connected, so second spot welding gun 13a also rotates in the second direction together with second rotor 24a.

[0037] FIG. 8 is a simplified schematic diagram showing a portion of the spot welding gun rotation unit 10a viewed in the direction opposite to the direction indicated by arrow Z. FIG. 8 simply illustrates the rotation unit 11a, the first arm portion 14a, and the second arm portion 17a. In the upper view of FIG. 8, the first arm portion 14a and the second arm portion 17a are positioned close to each other, with the same pitch width from the center, P1. In the center view of FIG. 8, the servo motor 22a is driven from the state shown in the upper view to rotate the first rotor 23a in the first direction and the second rotor 24a in the second direction. That is, the first arm portion 14a and the second arm portion 17a are rotated in directions that move them apart. In this case, the distance between the first arm portion 14a and the second arm portion 17a is increased, but the pitch width from the center is still the same, P2. In the lower diagram of Figure 8, servo motor 22a is further driven to rotate first rotor 23a in the first direction and second rotor 24a in the second direction. In this case, the distance between first arm portion 14a and second arm portion 17a is further increased to a position of 180 degrees when viewed from above, but the pitch width from the center is equal to P3. The rotation direction of servo motor 22a can also be reversed to bring first arm portion 14a and second arm portion 17a closer to each other.

[0038] In the rotation unit 11a configured as described above, when the main shaft portion 21a is rotated by the servo motor 22a serving as the drive source, the first rotating body 23a attached to the main shaft portion 21a rotates together with the main shaft portion 21a in a first direction around the central axis 20a of the main shaft portion 21a. Furthermore, when the first rotating body 23a rotates in the first direction, the second rotating body 24a rotates in a second direction, which is the opposite direction to the first direction, around the central axis 20a of the main shaft portion 21a via the first gear 51a, the second gear 52a, the third gear 53a, the fourth gear 54a, the fifth gear 55a, and the sixth gear 56a. In this case, the first gear 51a, the second gear 52a, the third gear 53a, the fourth gear 54a, the fifth gear 55a, and the sixth gear 56a are each disposed axially between the first rotor 23a and the second rotor 24a, thereby preventing the radial size from increasing. As described above, the rotation unit 11a can rotate multiple rotors with a single drive source, thereby reducing the radial size. Note that a configuration using such first gear 51a to sixth gear 56a can realize a configuration combining spur gears, which is suitable for use as a backlash-less structure.

[0039] Furthermore, since the spot welding gun rotation unit 10a includes the rotation unit 11a having the above-described configuration, it is possible to rotate a plurality of rotating bodies with one driving source, thereby enabling the radial size to be reduced.

[0040] In this embodiment, bearings (first bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a) that include rolling elements and rotatably support first rotating body 23a and second rotating body 24a, respectively, are included. First bearing 31a, second bearing 32a, third bearing 33a, and fourth bearing 34a include first roller 35a, second roller 36a, third roller 37a, and fourth roller 38a as rolling elements, respectively, which ensures smoother rotational movement of the rotating bodies supported by the bearings.

[0041] In this embodiment, the first rotor 23a and the second rotor 24a each include a first protrusion 45a and a second protrusion 46a, which protrude part of their circumferential portions toward the outer diameter side. Therefore, the first protrusion 45a and the second protrusion 46a can be used to easily attach a rotating member to the rotor. This improves convenience.

[0042] In this embodiment, servo motor 22a as a drive source is provided at the axial end of main shaft portion 21a, which simplifies the configuration for rotating main shaft portion 21a using servo motor 22a and also makes it possible to make the radial size more compact.

[0043] In this embodiment, the second rotor 24a has the same shape as the first rotor 23a, so that a common member can be used as the rotor, thereby improving productivity.

[0044] In this embodiment, the gear mechanism includes a first shaft portion 47a and a second shaft portion 49a, each of which is rotatably supported by the support portion 25a. The second gear 52a and the third gear 53a are coaxially fixed by the first shaft portion 47a. The fourth gear 54a and the fifth gear 55a are coaxially fixed by the second shaft portion 49a. Therefore, the second gear 52a and the third gear 53a can be easily rotated in the same direction by the first shaft portion 47a, and the fourth gear 54a and the fifth gear 55a can be easily rotated in the same direction by the second shaft portion 49a. This allows for a more compact device configuration while simplifying the configuration of each component.

[0045] In this embodiment, the second gear 52a has the same shape as the fifth gear 55a, and the third gear 53a has the same shape as the fourth gear 54a. Therefore, some of the multiple gears can be used as common components, which improves productivity.

[0046] In this embodiment, the first rotor 23a and the second rotor 24a each have a hollow cylindrical portion, which reduces the cost of materials used to make the rotors and reduces the weight of the rotary unit 11a.

[0047] In this embodiment, the drive source includes a servo motor 22a. Such a drive source is preferably used because it can be used even in harsh environments and can properly reverse the direction of rotation.

[0048] (Other embodiments) In the above embodiment, the first rotating body and the second rotating body are rotatably supported by bearings including rolling elements, but this is not limited to this, and at least one of the first rotating body and the second rotating body may be rotatably supported by a bearing including a rolling element, or, for example, one or both of the rotating bodies may be rotatably supported by a sliding bearing.

[0049] In the above embodiment, the rotation unit includes a first rotating body and a second rotating body that rotate in opposite directions, but is not limited to this. The rotation unit may include additional rotating bodies, such as a third rotating body that rotates in the same direction as the first rotating body, a fourth rotating body that rotates in the same direction as the second rotating body, etc. In this case, the rotation direction can be controlled by employing the above-described gear configuration.

[0050] In the above embodiment, a servo motor is used as the drive source, but this is not limiting, and other motors, for example, motors using rotary actuators such as rotary cylinders, can also be used.

[0051] The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention. [Explanation of symbols]

[0052] 10a Spot welding gun rotation unit, 11a rotation unit, 12a first spot welding gun, 13a second spot welding gun, 14a first arm portion, 15a first holder portion, 16a first electrode portion, 17a second arm portion, 18a second holder portion, 19a second electrode portion, 20a, 48a, 50a central shaft, 21a main shaft portion, 22a servo motor, 23a first rotating body, 24a second rotating body, 25a support portion, 26a first portion, 27a second portion, 28a third portion, 29a fourth portion, 30a base portion, 31a first bearing, 32a second bearing, 33a third bearing, 34a fourth bearing, 35a first roller, 36a second roller, 37a third roller, 38a fourth roller, 41a first side plate, 42a Second side plate, 43a, third side plate, 44a, fourth side plate, 45a, first protrusion, 46a, second protrusion, 47a, first shaft, 49a, second shaft, 51a, first gear, 52a, second gear, 53a, third gear, 54a, fourth gear, 55a, fifth gear, 56a, sixth gear, 57a, first gap, 58a, second gap, 59a, first window, 60a, second window.

Claims

1. A main shaft portion; a drive source that rotates the main shaft portion; a first rotor attached to the main shaft portion and rotating in a first direction around a central axis of the main shaft portion as the main shaft portion rotates; a second rotor arranged in parallel with the first rotor at an axial interval, and which rotates in a second direction opposite to the first direction around the central axis of the main shaft as a rotation of the main shaft; a support portion that rotatably supports the first rotating body and the second rotating body, a first gear attached to the first rotor and rotating together with the first rotor in the first direction around a central axis of the main shaft; a second gear that meshes with the first gear and rotates in the second direction; a third gear arranged axially apart from the second gear and rotating together with the second gear in the second direction; a fourth gear that meshes with the third gear and rotates in the first direction; a fifth gear that is spaced apart from the fourth gear in the axial direction and rotates together with the fourth gear in the first direction; a sixth gear attached to the second rotor, meshing with the fifth gear, and rotating together with the second rotor in the second direction around the central axis of the main shaft portion; A rotating unit, wherein the first gear, the second gear, the third gear, the fourth gear, the fifth gear, and the sixth gear are each arranged between the first rotating body and the second rotating body in the axial direction.

2. The rotary unit according to claim 1 , further comprising a bearing including a rolling element and rotatably supporting at least one of the first rotary element and the second rotary element.

3. The rotary unit according to claim 1 or 2, wherein at least one of the first rotary body and the second rotary body includes a protruding portion having a circumferential portion protruding radially outward.

4. 3. The rotation unit according to claim 1, wherein the drive source is provided at an axial end of the main shaft portion.

5. The rotary unit according to claim 1 or 2, wherein the second rotary body has the same shape as the first rotary body.

6. Further provided is a first shaft portion and a second shaft portion each rotatably supported by the support portion, the second gear and the third gear are coaxially fixed by the first shaft portion, 3. The rotation unit according to claim 1, wherein the fourth gear and the fifth gear are coaxially fixed by the second shaft portion.

7. the second gear has the same shape as the fifth gear, 3. The rotary unit according to claim 1, wherein the third gear has the same shape as the fourth gear.

8. The rotary unit according to claim 1 , wherein at least one of the first rotary body and the second rotary body has a hollow cylindrical portion.

9. The rotation unit according to claim 1 or 2, wherein the drive source includes a servo motor.

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