Dual rotary indexing apparatus

Abstract

To provide a configuration in which a spacing between two sets of rotary indexing units can be reduced in a dual rotary indexing apparatus having the two sets of rotary indexing units.SOLUTION: A dual rotary indexing apparatus includes two sets of rotary indexing units each of which includes a drive shaft that is rotationally driven by a drive motor, a disk-shaped driven member that is attached to a spindle, and a drive member that is provided on the drive shaft and has a helical groove that directly or indirectly engages with the driven member, in which the drive shaft is supported at one end side by a frame via a bearing holder incorporating a thrust bearing, and is supported at the other end side by the frame via a radial bearing, the drive shafts of both rotary indexing units are coupled via a coupling member, and the drive motor is connected to the end on an opposite side to a coupling member side of the drive shaft of the one rotary indexing unit. The other end of the drive shaft of the one rotary indexing unit is connected to the other end of the drive shaft of the other rotary indexing unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a double rotary indexing device comprising a rotary indexing unit including a main shaft having a rotation target member attached to one end thereof and rotatably supported within a frame, and a drive transmission mechanism that transmits the rotation of the output shaft of a drive motor to the main shaft, wherein the drive transmission mechanism includes a drive shaft that is rotationally driven by the drive motor, a disk-shaped driven member attached to the main shaft, and a drive member that has a spiral groove that directly or indirectly engages with the driven member and is provided on the drive shaft, wherein the drive shaft is supported on one end thereof by a bearing holder equipped with a thrust bearing, and the double rotary indexing device comprises two rotary indexing units that are supported on the other end thereof by a thrust bearing, the drive shafts of both rotary indexing units are connected by a connecting member, and the drive motor is connected to the end of one of the rotary indexing units on the side opposite to the connecting member side of the drive shaft. [Background technology]

[0002] In the field of machine tools, a so-called multiple rotary indexing device is known that has multiple sets of rotary indexing units for indexing the angular position of a workpiece. In this multiple rotary indexing device, the rotary indexing units include a main shaft rotatably supported within a frame and a drive transmission mechanism for transmitting the rotation of the output shaft of a drive motor to the main shaft.

[0003] In the rotary indexing unit, the spindle is configured so that a rotation target member (for example, a table on which a workpiece is fixed) is attached to one end thereof. The drive transmission mechanism is configured to include a drive shaft that is rotationally driven by a drive motor, a disk-shaped driven member attached to the spindle, and a drive member that has a spiral groove that directly or indirectly engages with the driven member and is provided on the drive shaft. An example of a multiple rotary indexing device equipped with multiple such rotary indexing units is the device disclosed in Patent Document 1.

[0004] More specifically, in the multiple rotary indexing device disclosed in Patent Document 1, in each rotary indexing section (indexing unit) in the multiple rotary indexing device, the drive transmission mechanism is a worm gear mechanism including a worm shaft as a drive shaft that is rotationally driven by a drive motor, a worm as a driving member provided on the worm shaft, and a worm wheel as a driven member attached to the main shaft. As is well known, the worm gear mechanism is configured so that the worm wheel directly meshes (engages) with a worm groove formed in a spiral shape on the outer periphery of the worm.

[0005] In the drive transmission mechanism of the rotation indexing unit, the worm shaft is supported on the frame via bearings, one end of which is supported via a ball bearing as a thrust bearing, and the other end is supported via a roller bearing as a radial bearing. That is, to support the drive shaft (worm shaft) in the drive transmission mechanism (worm gear mechanism) as described above, a thrust bearing (ball bearing) that can withstand a load in the axial direction (thrust direction) is used to support one end of the drive shaft (worm shaft) so that the position of the driving member (worm) does not change in the axial direction of the drive shaft due to reaction force from the driven member (worm wheel).

[0006] Also, as in the multiple rotary indexing device of Patent Document 1, support by a thrust bearing at one end side is achieved by attaching a bearing holder (bearing housing) that houses the thrust bearing to a frame. More specifically, in the drive transmission mechanism, the position of the driving member in the axial direction needs to be a desired position so that it can be properly engaged with the driven member. Therefore, when assembling the drive shaft on which the driving member is provided to the frame, the assembly needs to be performed while adjusting (aligning) the position of the drive shaft so that the position of the driving member in the axial direction is the desired position.

[0007] The radial bearing used to support the other end is a bearing specialized for bearing radial loads, and is therefore generally mounted in a state where axial displacement is permitted relative to the frame. In contrast, the thrust bearing used to support one end is a bearing designed to bear thrust loads in addition to radial loads, and is therefore mounted in a state where axial displacement is not permitted relative to the frame (i.e., where the axial position is fixed relative to the frame). Therefore, if the thrust bearing is directly assembled to the frame, its position is fixed upon assembly, and therefore the position of the drive shaft relative to the frame is also fixed, making it difficult to adjust the axial position during assembly.

[0008] Therefore, in the drive transmission mechanism described above, a thrust bearing is used to support one end as described above, and the thrust bearing is generally provided in a bearing holder that houses the thrust bearing and is attached to the frame so that the position of the thrust bearing relative to the frame can be easily adjusted when assembling the drive shaft.

[0009] In a conventional multiple rotary indexing device, each rotary indexing unit is incorporated into the device with the orientation of its drive shaft (the positional relationship of the one end side and the other end side of the drive shaft in the axial direction with respect to the drive member) being the same. Therefore, in two sets of rotary indexing units adjacent in the axial direction, the one end side of the drive shaft in one rotary indexing unit and the other end side of the drive shaft in the other rotary indexing unit are opposed to each other. In addition, in such a multiple rotary indexing device, the one end side of one drive shaft and the other end side of the other drive shaft, which are opposed to each other as described above, are connected by a connecting member, and the drive shafts of each rotary indexing unit are connected to each other.

[0010] In such a conventional multiple rotary indexing device, the drive motor is generally provided in a form connected to the end of one of the drive shafts located on the outside in the axial direction when the plurality of drive shafts are connected as described above, on the side opposite to the connection (connecting member) side. By providing the drive motor in such a form of connection, in the conventional multiple rotary indexing device, it is possible to avoid an increase in the size of the rotary indexing device itself or the machine tool in which the rotary indexing device is installed. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-066877 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the conventional multiple rotary indexing device as described above, the distance in the axial direction between two sets of rotary indexing units adjacent to each other in the axial direction becomes large, which causes a problem that the rotary indexing device itself becomes large.

[0013] As described above, in a conventional multiple rotary indexing device, two sets of rotary indexing units adjacent to each other in the axial direction are configured so that the one end of the drive shaft in one rotary indexing unit and the other end of the drive shaft in the other rotary indexing unit are connected to each other by a connecting member. Therefore, in this configuration, the connecting position of the drive shafts of the two sets of rotary indexing units is naturally located between both rotary indexing units, and the thrust bearing supporting the one end of the drive shaft in one rotary indexing unit is located on the drive member side (in that rotary indexing unit) of the connecting position.

[0014] As described above, the thrust bearing used to support the one end is housed in a bearing holder and attached to the frame via the bearing holder. Generally, the outer diameter of the thrust bearing is larger than that of the radial bearing used to support the other end. Therefore, the bearing holder that houses the thrust bearing also necessarily has a large outer diameter. Therefore, in the configuration of the multiple rotary indexing device, the large-diameter bearing holder is located at a position on the drive shaft of each rotary indexing unit.

[0015] Regarding the position of the bearing holder on the drive shaft, at each rotation indexing portion, there is a disk-shaped driven member with a large outer diameter that meshes with the driving member provided on the drive shaft. Therefore, the position of the large-diameter bearing holder on the drive shaft must be located away from the driving member to avoid interference with the driven member if it is located closer to the driving member. In other words, the support at one end of the drive shaft is located farther from the driving member than the other end.

[0016] Furthermore, the drive shaft of one of the rotary indexing units is connected at its one end to the drive shaft of the other adjacent rotary indexing unit, but the connection position is naturally outside the support position of the one end (opposite the drive member side), so that in the one rotary indexing unit, the distance from the drive member to the connection position of the one end is necessarily large. As a result, in conventional multiple rotary indexing devices, the distance between the two rotary indexing units is large, which causes the problem of the entire device becoming large.

[0017] In view of the above problems, the present invention aims to provide a configuration in which, among the multiple rotary indexing devices as described above, particularly in a double rotary indexing device having two sets of rotary indexing units, the spacing between the two sets of rotary indexing units can be reduced in the axial direction of the drive shaft, thereby making the entire device smaller. [Means for solving the problem]

[0018] The present invention is based on a dual rotary indexing device, which is provided with a rotary indexing unit including a main shaft having a rotation target member attached to one end thereof and rotatably supported within a frame, and a drive transmission mechanism that transmits the rotation of the output shaft of a drive motor to the main shaft, wherein the drive transmission mechanism includes a drive shaft that is rotationally driven by the drive motor, a disk-shaped driven member attached to the main shaft, and a drive member that has a spiral groove that directly or indirectly engages with the driven member and is provided on the drive shaft, wherein the drive shaft is supported on one end thereof by a bearing holder equipped with a thrust bearing, and the other end thereof is supported on the frame via a radial bearing, and the drive shafts of both rotary indexing units are connected by a connecting member, and the drive motor is connected to the end of one of the rotary indexing units on the side opposite to the connecting member side of the drive shaft.

[0019] Furthermore, the present invention is characterized in that the dual rotary indexing device is configured so that the other end of the drive shaft in one rotary indexing unit is connected to the other end of the drive shaft in the other rotary indexing unit. [Effects of the Invention]

[0020] According to the present invention, in the dual rotary indexing device based on the above-described premise, the dual rotary indexing device is configured so that the other end of the drive shaft in one rotary indexing unit is connected to the other end of the drive shaft in the other rotary indexing unit. As a result, each rotary indexing unit is arranged in the device with one end of the drive shaft supported by a thrust bearing located axially outward from the connecting position connecting the two drive shafts. Therefore, in this configuration, the bearing holders provided to support the drive shafts in each rotary indexing unit are located on the outer side of the respective drive members, i.e., on the opposite side from the connecting position relative to the drive members. The two rotary indexing units are connected between radial bearings supporting the other end of each drive shaft.

[0021] Since the radial bearing has a smaller outer diameter than the thrust bearing and does not require a bearing holder like the thrust bearing, its position on the drive shaft can be closer to the drive member. This allows the coupling position to be closer to both drive members than in the conventional configuration described above. Therefore, with this configuration, the distance between both rotation indexing units can be reduced in the axial direction, allowing the overall device to be made smaller. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a top cross-sectional view showing a dual rotary indexing device to which the present invention is applied. [Figure 2] FIG. 2 is a cross-sectional view (side cross-sectional view) taken along the line AA in FIG. [Figure 3] FIG. 2 is an enlarged view of a main part of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment (example) of a dual rotary indexing device to which the present invention is applied will be described with reference to the drawings.

[0024] 1 to 3 show a dual rotary indexing device 1 to which the present invention is applied. The dual rotary indexing device 1 shown in the figures is a so-called horizontally-mounted dual rotary indexing device in which the axis of the main shaft is oriented vertically. The dual rotary indexing device 1 includes a frame 2 attached to a machine tool, two sets of rotary indexing units 10, 10 provided within the frame 2, and a drive motor 3 for rotating and driving each of the rotary indexing units 10. The two sets of rotary indexing units 10, 10 have substantially the same configuration. Therefore, in the following, only one of the two sets of rotary indexing units 10, 10 will be described, and a description of the other will be omitted.

[0025] 2 and 3, the rotation indexing unit 10 includes a main shaft 11 that is rotatably supported relative to the frame 2 in the space within the frame 2, and a table 12 that serves as a rotation target member attached to one end of the main shaft 11. The rotation indexing unit 10 also includes a drive transmission mechanism 30 that transmits the rotation of the output shaft of the drive motor 3 to the main shaft 11, and a clamping device 18 that holds (clamps) the main shaft 11 at the indexed angular position.

[0026] More specifically, the main spindle 11 is rotatably supported by bearings 14 with its axis oriented vertically in the space within the frame 2. The table 12 is a disk-shaped member for mounting a workpiece to be machined, and is attached to one end of the main spindle 11 with a plurality of mounting bolts (not shown) with its end face abutting against the main spindle 11 so as to be unable to rotate relative to the main spindle 11.

[0027] Furthermore, this embodiment is an example in which a so-called worm gear mechanism including a disk-shaped worm wheel and a worm directly engaged with the worm wheel is adopted as the drive transmission mechanism 30. More specifically, the worm gear mechanism (drive transmission mechanism) 30 is composed of a drive shaft 33 that is rotationally driven by the drive motor 3, a disk-shaped worm wheel 35 that is attached to the main shaft 11 as a driven member, and a worm 34 that is provided on the drive shaft 33 as a driving member.

[0028] Worm wheel 35 is attached within the space of frame 2 so as to be unable to rotate relative to main shaft 11. Worm wheel 35 is made up of a shaft-shaped shaft portion attached to main shaft 11 and a flange-shaped portion formed to protrude radially from the shaft portion and having helical teeth formed on the outer circumferential surface. Worm wheel 35 is provided so that the flange portion is located approximately in the center of main shaft 11 in the axial direction of main shaft 11.

[0029] The drive shaft 33 is disposed in the frame 2 with its axis oriented horizontally (perpendicular to the axis of the main shaft 11). The frame 2 is provided with an accommodation hole 25 for accommodating the drive shaft 33. The accommodation hole 25 communicates with the space and penetrates the frame 2 in the horizontal direction. The accommodation hole 25 has a diameter larger than the thickness of the flange portion of the worm wheel 35. The accommodation hole 25 is positioned in the axial direction of the main shaft 11 so as to include the extent of the flange portion. The drive shaft 33 is rotatably supported within the accommodation hole 25 via a bearing relative to the frame 2.

[0030] A worm 34 is provided on the drive shaft 33 supported in the accommodating hole 25 in this manner. The worm 34 is provided in approximately the center of the drive shaft 33. As is well known, the worm 34 is a gear with spiral teeth formed on its outer periphery, and has a spiral groove formed by the teeth on its outer periphery. With the worm 34 provided on the drive shaft 33 in this manner, the groove meshes with the helical teeth of the flange portion of the worm wheel 35.

[0031] In this embodiment, the worm 34 is a so-called double-lead worm in which the lead of the tooth surface is slightly different on the left and right sides, and the tooth thickness dimension gradually increases toward one side in the axial direction of the drive shaft 33. As is well known, in the worm gear mechanism 30 including such a double-lead worm 34, backlash between the worm 34 and the flange portion of the worm wheel 35 is adjusted by displacing the worm 34 in the axial direction of the drive shaft 33.

[0032] In the dual rotary indexing device 1 in which the rotary indexing unit 10 has the above-described configuration, the two sets of rotary indexing units 10, 10 are arranged in the frame 2 so that the axes of the drive shafts 33, 33 coincide when viewed in the axial direction, and are aligned in the axial direction. In addition, the end of the drive shaft 33 in one rotary indexing unit 10 and the end of the drive shaft 33 in the other rotary indexing unit 10 are connected by a coupling 5 serving as a connecting member.

[0033] The connected drive shafts 33, 33 are connected to a drive motor 3 for driving the drive shafts 33, 33. More specifically, the frame 2 has a hole 26 formed in one of the two side surfaces on which the accommodating hole 25 opens, which is a bottomed hole for receiving the output shaft of the drive motor 3. The hole 26 is located above the accommodating hole 25 when viewed in the axial direction of the drive shaft 33, and is formed so that a portion of the hole 26 overlaps with the accommodating hole 25. A plate-shaped motor bracket 27 is attached to the one side surface of the frame 2 so as to cover the openings of the accommodating hole 25 and the hole 26. The motor bracket 27 has a through-hole formed in a position communicating with the hole 26.

[0034] The drive motor 3 is mounted to the motor bracket 27 with its output shaft received in the hole 26 through the through-hole of the motor bracket 27. A pinion gear 31 is mounted on the output shaft of the drive motor 3. Of the two drive shafts 33, 33 connected as described above, the drive shaft 33 on the drive motor 3 side has a driven gear 32 that meshes with the pinion gear 31 mounted on the end of the drive shaft 33 on the side opposite to the coupling 5 (connecting member) side (drive motor 3 side). As a result, both drive shafts 33, 33 are connected to the drive motor 3 via the driven gear 32 and pinion gear 31 at the end of the drive shaft 33 in one rotation indexing unit 10 opposite to the connecting member side.

[0035] As described above, each rotation indexing unit 10 is provided with a clamping device 18 for holding the spindle 11 at an indexed angular position as a result of both drive shafts 33, 33 being rotationally driven by the connected drive motor 3. In the illustrated example, the clamping device 18 is a so-called disk-type clamping device. Specifically, the clamping device 18 includes a clamping disc 15 attached to the spindle 11 side and a clamping piston 16 that presses the clamping disc 15 against a clamping surface provided on the frame 2. When a working fluid is supplied to a pressure chamber 17 defined by the clamping piston 16 and the frame 2, the pressure of the working fluid causes the clamping disc 15 to be clamped between the clamping piston 17 and the clamping surface, thereby holding the spindle 11 (a clamped state).

[0036] In the dual rotary indexing device 1 as described above, in the present invention, the drive shaft 33 of each rotary indexing unit 10 is supported at one end by the frame 2 via a thrust bearing, and at the other end by the frame 2 via a radial bearing. However, the thrust bearing supporting the drive shaft 33 at one end is provided in a bearing holder and is attached to the frame 2 via the bearing holder. In addition, in the dual rotary indexing device 1 of the present invention, both rotary indexing units 10, 10 are arranged such that the other end of the drive shaft 33 in one rotary indexing unit 10 is connected to the other end of the drive shaft 33 in the other rotary indexing unit 10. One embodiment (example) of such a dual rotary indexing device 1 will be described in detail below.

[0037] In the double rotary indexing device 1, the drive shaft 33 of each rotary indexing unit 10 is supported on the frame 2 at one end 33a via a thrust bearing 41 as described above, and is also supported on the frame 2 at the other end 33b via a radial bearing 43. In this embodiment, the thrust bearing 41 is an angular contact ball bearing, and the radial bearing 43 is a roller bearing.

[0038] In the double rotary indexing device 1, as described above, both rotary indexing units 10, 10 are provided in such a manner that the end portion of the other end 33b of the drive shaft 33 in one rotary indexing unit 10 is connected to the end portion of the other end 33b of the drive shaft 33 in the other rotary indexing unit 10. Therefore, one (right side in FIG. 1) rotary indexing unit 10 is configured so that one end 33a of the drive shaft 33 is on one of the two side surfaces on which the accommodation hole 25 of the frame 2 opens (the drive motor 3 side), and the other (left side in FIG. 1) rotary indexing unit 10 is configured so that one end 33a of the drive shaft 33 is on the other of the two side surfaces (the side opposite to the drive motor 3 side).

[0039] Therefore, in each rotation indexing unit 10, the position where the angular ball bearing 41 supporting the end of one end 33a of the drive shaft 33 is provided is the corresponding end of the accommodation hole 25 of the frame 2. Then, at the end of the accommodation hole 25, the angular ball bearing 41 supporting the drive shaft 33 is accommodated in a bearing holder 40 and is attached to the frame 2 via the bearing holder 40. That is, on the side of one end 33a, each drive shaft 33 is supported by the frame 2 at the end of the accommodation hole 25 via the bearing holder 40 in which the angular ball bearing 41 is accommodated.

[0040] Each bearing holder 40 is a hollow cylindrical member having a through hole 40d in the center in which an angular contact ball bearing 41 is fitted. The bearing holder 40 is formed so that the outer diameter of one end of the bearing holder 40 in the axial direction is larger than the outer diameter of the remaining portion. In other words, the bearing holder 40 is configured to consist of a large-diameter portion 40b at the one end and a main body portion 40a that is the portion excluding the large-diameter portion 40b.

[0041] In contrast, accommodation hole 25 is formed to have enlarged diameter portions 25b at both ends, which have a larger diameter than the remaining portions. Furthermore, in accommodation hole 25, a portion (communicating portion) 25c that communicates between portion (accommodating portion) 25a where worm 34 is accommodated and enlarged diameter portion 25b needs to have a hole diameter equal to or larger than the outer diameter of worm 34 so that worm 34 can be inserted from the outside toward accommodation portion 25a. In the illustrated example, the hole diameter is the same as the hole diameter of accommodation portion 25a.

[0042] Moreover, the large diameter portion 40b of the bearing holder 40 is formed so that its outer diameter is approximately the same as the hole diameter of the expanded diameter portion 25b of the corresponding accommodating hole 25. The main body portion 40a is formed so that its outer diameter is approximately the same as the hole diameter of the communicating portion 25c of the accommodating hole 25. Each bearing holder 40 is oriented so that the large diameter portion 40b faces the opening side (outside) of the accommodating hole 25, and the main body portion 40a is fitted into the communicating portion 25c at the corresponding end of the accommodating hole 25.

[0043] A female thread is formed on the inner peripheral surface of each enlarged diameter portion 25b of the accommodating hole 25, while a male thread is formed on the outer peripheral surface of the large diameter portion 40b of each bearing holder 40. As a result, each bearing holder 40 is attached to the frame 2 with the male thread of its large diameter portion 40b screwed into the female thread of the enlarged diameter portion 25b of the accommodating hole 25. With this configuration, the position of the bearing holder 40 relative to the frame 2 can be changed in the axial direction of the drive shaft 33 by rotating the bearing holder 40 (the male thread of the large diameter portion 40b) relative to the frame 2 (the female thread of the enlarged diameter portion 25b).

[0044] Additionally, female threaded holes 42a are formed in the frame 2, each opening into the communicating portion 25c of the accommodating hole 25 and drilled so as to penetrate horizontally from the rear surface of the frame 2 toward the accommodating hole 25. A setscrew 42b is threaded into each female threaded hole 42a. The position of each bearing holder 40 relative to the frame 2 is fixed by pressing each setscrew 42b against the outer peripheral surface of the main body portion 40a of the bearing holder 40 inserted into the communicating portion 25c as described above.

[0045] As described above, an angular ball bearing 41 is installed inside each bearing holder 40 attached to the frame 2 in this manner, and in the illustrated example, two angular ball bearings 41 are provided in each through hole 40d. In each through hole 40d, the two angular ball bearings 41, 41 are provided facing each other with a gap between them.

[0046] Furthermore, the roller bearing 43 used to support the other end 33b of the drive shaft 33 is a bearing specialized for bearing radial loads, and therefore the roller bearing 43 is directly fitted into the accommodating hole 25 on the other end 33b side, and is provided in a state in which its axial displacement is permitted.

[0047] As described above, the bearing holder 40, which houses the angular contact ball bearing 41 that supports one end 33a of the drive shaft 33, is provided so as to be displaceable in the axial direction of the drive shaft 33 relative to the frame 2. The roller bearing 43 that supports the other end 33b of the drive shaft 33 is provided so as to be permitted to move in the axial direction. As a result, in the worm gear mechanism 30 employing the dual-lead worm 34 described above, by displacing the bearing holder 40 in the axial direction of the drive shaft 33 relative to the frame 2, the worm 34 can be displaced in the axial direction of the drive shaft 33 relative to the worm wheel 35, thereby adjusting the backlash.

[0048] As described above, the worm 34 accommodated in the accommodation hole 25 (accommodating portion 25a) is provided to mesh with the worm wheel 35 provided in the space of the frame 2, and the accommodation hole 25 is formed so as to communicate with the space at the accommodation portion 25a. Furthermore, this communication is achieved by forming an opening in the accommodation portion 25a that extends in the axial direction of the drive shaft 33. As a result, in the accommodation hole 25, a portion of the accommodation portion 25a overlaps with a portion of the space in the axial direction of the drive shaft 33, and a portion of the disk-shaped worm wheel 35 enters the accommodation portion 25a in the radial direction through the opening.

[0049] Furthermore, roller bearing 43 is provided in accommodating hole 25 in a portion (fitting portion) 25d opposite communicating portion 25c relative to accommodating portion 25a, so as to be directly fitted into accommodating hole 25 (fitting portion 25d) as described above. The outer diameter of roller bearing 43 is generally smaller than that of angular contact ball bearing 41 used to support one end 33a of drive shaft 33. Therefore, fitting portion 25d in accommodating hole 25 is formed to have a smaller diameter than accommodating portion 25a and communicating portion 25c.

[0050] As described above, the fitting portion 25d and the communicating portion 25c are portions that are continuous with (communicate with) the accommodation portion 25a on both sides of the accommodation portion 25a. The fitting portion 25d is formed so that its hole diameter is smaller than the hole diameter of the communicating portion 25c. Therefore, in terms of the relationship with the worm wheel 35 that enters the accommodation portion 25a as described above, the fitting portion 25d can be formed at a position closer to the worm 34 than the communicating portion 25c.

[0051] Therefore, in the rotation indexing unit 10, the fitting portion 25d is formed at a position closer to the worm 34 than the communicating portion 25c. As a result, the position of the roller bearing 43 arranged in the fitting portion 25d, i.e., the support position of the other end 33b of the drive shaft 33 by the roller bearing 43, is closer to the worm 34 than the support position of the one end 33a of the drive shaft 33 by the angular ball bearing 41.

[0052] In this way, in both rotary indexing units 10, 10 of the dual rotary indexing device 1, the drive shaft 33 is provided in such a way that the other end 33b side by the roller bearing 43 is supported at a position closer to the worm 34 than the one end 33a side by the angular ball bearing 41 (bearing holder 40). Accordingly, the drive shaft 33 in each rotary indexing unit 10 is formed so that the distance from the worm 34 on the drive shaft 33 to the shaft end is shorter on the other end 33b side than on the one end 33a side.

[0053] In addition, as described above, the dual rotary indexing device 1 is configured so that the other end 33b of the drive shaft 33 in one rotary indexing unit 10 is connected to the other end 33b of the drive shaft 33 in the other rotary indexing unit 10. Therefore, with this configuration, the distance from the position of the worm 34 in one rotary indexing unit 10 to the connection position of both drive shafts 33, 33 is shorter than in a dual rotary indexing device in which, for example, the drive shaft 33 in one rotary indexing unit 10 is connected at its one end 33a to the drive shaft 33 (other end 33b) in the other rotary indexing unit 10.

[0054] In the rotary indexing unit 10, the position of the worm 34 corresponds to the position of the main shaft 11 in the axial direction of the drive shaft 33, and therefore the distance from the position of the worm 34 in one rotary indexing unit 10 to the connecting position of both drive shafts 33, 33 becomes shorter as described above, thereby reducing the interval between both main shafts 11, 11 in the dual rotary indexing device 1. Therefore, with such a configuration, the interval between both rotary indexing units 10, 10 can be made as small as possible in the axial direction of the drive shaft 33, and the entire dual rotary indexing device 1 can be made compact.

[0055] Although one embodiment of the dual rotary indexing device of the present invention has been described above, the dual rotary indexing device of the present invention is not limited to the above embodiment, and can be implemented in the following modified examples.

[0056] (1) Regarding the drive transmission mechanism, in the above embodiment, a worm gear mechanism 30 consisting of a wormhole 35 and a worm 34 is employed as the drive transmission mechanism for transmitting the rotation of the output shaft of the drive motor 3 to the main shaft 11. In addition, in the above embodiment, a double-lead worm is employed as the worm 34 in the worm gear mechanism 30.

[0057] However, in the present invention, even when a worm gear mechanism is used as the drive transmission mechanism, the worm is not limited to a double-lead type as in the above embodiment, and may be a so-called single-lead worm formed so that the tooth thickness is constant along the axial direction of the drive shaft 33. Note that if the worm is a single-lead type, backlash between the worm and the worm wheel cannot be adjusted by displacing the worm along the axial direction of the drive shaft 33. Therefore, the dual rotary indexing device does not need to be configured so that the drive shaft's position can be adjusted along its axial direction as in the above embodiment. Therefore, in this case, the bearing holder may be configured so that its position along the axial direction of the drive shaft cannot be changed. In other words, the dual rotary indexing device may be configured so that the bearing holder is fixed at a specific position.

[0058] Furthermore, the drive transmission mechanism is not limited to the worm gear mechanism of the above embodiment, in which a worm, which is a driving member, directly engages with a worm wheel, which is a driven member, via a spiral groove, but may be another type of drive transmission mechanism in which the driving member indirectly engages with a driven member via a spiral groove. Specifically, the drive transmission mechanism may be a so-called ball drive mechanism, in which the worm wheel and worm are connected via steel balls. The drive transmission mechanism may also be a so-called roller gear cam mechanism, in which a turret wheel with multiple roller followers attached at intervals to its outer periphery is connected to a roller gear cam having spiral cam grooves corresponding to the rollers of the roller followers. In the case of the roller gear cam mechanism, the turret wheel corresponds to the driven member, and the roller gear cam corresponds to the driving member.

[0059] (2) Regarding the frame of the dual rotary indexing device, in the above-described embodiment, the dual rotary indexing device 1 is configured such that the frame 2 on which the two sets of rotary indexing units 10, 10 are arranged is an integrally molded member. However, the dual rotary indexing device is not limited to a device configured with a frame formed in this manner, and may be configured such that the frame is formed by combining (connecting) two members on which the two sets of rotary indexing units are respectively arranged. In this case, each member forming the frame has a through hole that becomes the accommodation hole when combined, and one of the side surfaces of both members (the surface on which the through hole opens) is formed as a connecting surface that is perpendicular to the penetration direction of the accommodation hole (parallel to the axis of the main shaft). Then, both members are combined with their connecting surfaces abutting to form the frame.

[0060] (3) Regarding the dual rotary indexing device on which the present invention is based, in the above-described embodiment, the dual rotary indexing device 1 is a so-called horizontally-mounted dual rotary indexing device in which the axis of its main shaft is oriented vertically. However, the dual rotary indexing device to which the present invention is applied is not limited to such a horizontally-mounted dual rotary indexing device, and may also be a so-called vertically-mounted dual rotary indexing device in which the axis of the main shaft is oriented horizontally. Furthermore, the dual rotary indexing device to which the present invention is applied is not limited to one in which the frame is directly attached to the machine tool as described above. For example, the present invention may be applied to the rotary indexing portion of a so-called oblique rotary indexing device having two types of rotary indexing portions, an oblique indexing portion and a rotary indexing portion.

[0061] The present invention is not limited to any of the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0062] 1. Dual rotary indexing device 2 frames 3 Drive motor 5 Coupling (connecting member) 10 Rotation indexing unit 11 Spindle 12 Table (rotating object) 14 Bearings 15 Clamping disc 16 Clamp piston 17 Pressure Chamber 18 Clamping device 25 Receiving hole 25a Storage section 25b Expanded diameter part 25c Communication part 25d Fitting part 26 holes 27 Motor bracket 30 Worm gear mechanism (drive transmission mechanism) 31 Pinion gear 32 Driven gear 33 Drive shaft 33a one end 33b other end 34 Worm (driving member) 35 Worm wheel (driven member) 40 Bearing holder 40a Main body 40b Large diameter part 40d through hole 41 Angular contact ball bearing (thrust bearing) 42a female screw hole 42b Set screw 43 Roller bearing (radial bearing)

Claims

[Claim 1] A dual rotary indexing device comprising a main shaft to which a rotation target member is attached at one end and which is rotatably supported within a frame, and a drive transmission mechanism for transmitting rotation of an output shaft of a drive motor to the main shaft, wherein the drive transmission mechanism comprises a drive shaft which is rotationally driven by the drive motor, a disk-shaped driven member attached to the main shaft, and a drive member which has a spiral groove which engages directly or indirectly with the driven member and is provided on the drive shaft, wherein the drive shaft is supported at one end by the frame via a bearing holder incorporating a thrust bearing, and the other end by the frame via a radial bearing, the dual rotary indexing device comprises two sets of rotary indexing units, the drive shafts of both rotary indexing units being connected by a connecting member, and the drive motor being connected to an end of the drive shaft of one of the rotary indexing units on the side opposite to the connecting member side, The other end of the drive shaft in the one rotary indexing portion and the other end of the drive shaft in the other rotary indexing portion are configured to be connected to each other. A dual rotary indexing device.

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