Double rotary indexing device

Abstract

This invention provides a structure that reduces the distance between the two sets of rotary indexing sections in a double rotary indexing device having two sets of rotary indexing sections. The double rotary indexing device is configured to have two sets of rotary indexing sections, each comprising: a disc-shaped drive shaft driven by a drive motor; a driven member mounted on a main shaft; and a drive member having a helical groove that directly or indirectly engages with the driven member and disposed on the drive shaft; the drive shaft is supported at one end by a frame via a bearing cage housing a thrust bearing, and at the other end by a frame via a radial bearing; the drive shafts of the two rotary indexing sections are connected by a connecting member, the drive motor being connected to the end of the drive shaft in one of the rotary indexing sections opposite to the side of the connecting member; the other end of the drive shaft in one of the rotary indexing sections is connected to the other end of the drive shaft in the other rotary indexing section.

Description

Double Rotating Indexing Device The present invention relates to a double rotating indexing device, which has two sets of rotating indexing parts. The rotating indexing part includes: a main shaft, which has a rotating object member mounted on one end side and is supported in a frame so as to be rotatable; and a drive transmission mechanism, which transmits the rotation of the output shaft of a drive motor to the main shaft. The drive transmission mechanism includes: a drive shaft, which is rotationally driven by the drive motor; a disk-shaped driven member, which is mounted on the main shaft; and a drive member, which has a spiral groove that directly or indirectly engages with the driven member and is provided on the drive shaft. The drive shaft is supported by the frame via a bearing holder with a thrust bearing installed on one side of one end, and is supported by the frame via a radial bearing on one side of the other end. The drive shafts of the two rotating indexing parts are connected by a connecting member, and the drive motor is connected to the end of the drive shaft in one of the rotating indexing parts on the side opposite to the connecting member side. In the field of machine tools, there is known a so-called multi-rotating indexing device having a plurality of sets of rotating indexing parts for indexing the angular position of a workpiece. In this multi-rotating indexing device, the rotating indexing part includes: a main shaft, which is supported in a frame so as to be rotatable; and a drive transmission mechanism, which is used to transmit the rotation of the output shaft of a drive motor to the main shaft. In addition, in this rotating indexing part, the main shaft is configured to have a rotating object member (for example, a worktable for fixing a workpiece, etc.) mounted on one end side. And, the drive transmission mechanism is configured to include: a drive shaft, which is rotationally driven by the drive motor; a disk-shaped driven member, which is mounted on the main shaft; and a drive member, which has a spiral groove that directly or indirectly engages with the above-mentioned driven member and is provided on the drive shaft. Moreover, as an example of a multi-rotating indexing device having a plurality of such rotating indexing parts, there is a device disclosed in Patent Document 1. Regarding the multi-rotating indexing device disclosed in Patent Document 1, specifically, in each rotating indexing part (indexing unit) of this multi-rotating indexing device, the drive transmission mechanism is a worm and gear mechanism, which includes: a worm shaft as the drive shaft, which is rotationally driven by the drive motor; a worm as the drive member, which is provided on the worm shaft; and a gear as the driven member, which is mounted on the main shaft. And, as is well known, this worm and gear mechanism has a structure in which the gear directly meshes (engages) with the worm groove formed spirally on the outer periphery of the worm. Also, in the drive transmission mechanism of the rotary indexing unit, the worm shaft is supported relative to the frame via bearings. However, the support on one end side is carried out via a ball bearing as a thrust bearing, and the support on the other end side is carried out via a roller bearing as a radial bearing. That is, in the support of the drive shaft (worm shaft) of the above drive transmission mechanism (worm and worm gear mechanism), in order for the position of the drive member (worm) not to change in the axial direction of the drive shaft even when receiving a reaction force from the driven member (worm gear), a thrust bearing (ball bearing) capable of withstanding the load in the above axial direction (thrust direction) is adopted for the support on one end side. Also, the same is true for the multi-stage rotary indexing device in Patent Document 1. The support on one end side carried out by the thrust bearing is in the form of installing a bearing cage (bearing housing) with an internal thrust bearing on the frame. Specifically, in this drive transmission mechanism, the position of the drive member in the above axial direction needs to be a desired position for appropriately engaging with the driven member. Therefore, when assembling the drive shaft of the drive member relative to the frame, it is necessary to carry out the assembly in a manner that adjusts (aligns) the position of the drive shaft so that the position of the drive member in the above axial direction becomes the desired position. In addition, regarding the radial bearing used for the support on the other end side, since it is a bearing specifically for withstanding the load in the radial direction, it is generally set in a state allowing displacement in the axial direction relative to the frame. In contrast, regarding the thrust bearing used for the support on one end side, since it is a bearing for withstanding not only the load in the radial direction but also the load in the thrust direction, it is set in a state not allowing the above displacement in the axial direction relative to the frame (a state fixing the position in the above axial direction relative to the frame). Therefore, in a structure where the thrust bearing is directly assembled to the frame, at the moment of assembly, the position is fixed, and accordingly, the position of the drive shaft relative to the frame is also fixed, making it difficult to carry out the above position adjustment in the axial direction during assembly. Therefore, in the above drive transmission mechanism, as described above, a thrust bearing is used for the support on one end side. On this basis, the thrust bearing is generally set in the form of installing a bearing cage with an internal thrust bearing on the frame so that the position adjustment of the drive shaft relative to the frame during assembly can be easily carried out. Moreover, in the conventional multi-stage rotary indexing device, each rotary indexing unit is installed in the device in such a manner that the directions of the drive shafts (the positional relationships of the one end side and the other end side of the drive shaft with respect to the drive member in the above-mentioned axial direction) are the same. Therefore, in the above-mentioned axial direction, two adjacent sets of rotary indexing units are in a state where the one end side of the drive shaft in one rotary indexing unit faces the other end side of the drive shaft in the other rotary indexing unit. On this basis, in such a multi-stage rotary indexing device, as described above, the one end side of the drive shaft in the state of facing and the other end side of the drive shaft in the other rotary indexing unit are connected by a connecting member, and the drive shafts in each rotary indexing unit are connected to each other. And, in such a conventional multi-stage rotary indexing device, generally, the drive motor is arranged in a form that is connected to one end side of the drive shaft located on the outer side in the above-mentioned axial direction and on the side opposite to the connecting (connecting member) side in a state of being connected to a plurality of drive shafts as described above. Moreover, the drive motor is arranged in such a connected form, so in the conventional multi-stage rotary indexing device, the enlargement of the rotary indexing device itself or the machine tool on which the rotary indexing device is installed is avoided. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-066877. [Problems to be Solved by the Invention] However, in the above-mentioned conventional multi-stage rotary indexing device, the interval in the above-mentioned axial direction between two adjacent sets of rotary indexing units in the above-mentioned axial direction becomes large, and there is a problem that the rotary indexing device itself becomes large. The details are as follows. As described above, in the conventional multi-stage rotary indexing device, two adjacent sets of rotary indexing units in the above-mentioned axial direction are configured such that 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 connected to each other by a connecting member. Therefore, in this structure, of course, the connection position of the drive shafts of the two sets of rotary indexing units exists between the two rotary indexing units, and the thrust bearing that supports the one end side of the drive shaft in one rotary indexing unit is located at a position on the drive member side (in this rotary indexing unit) compared to this connection position. In addition, as described above, the thrust bearing used for the support of the above-mentioned one end side is internally installed in the bearing retainer and is installed on the frame via the bearing retainer. And generally, the outer diameter of the thrust bearing is larger than the outer diameter of the radial bearing used for the support of the above-mentioned other end side. Therefore, the bearing retainer that internally installs this thrust bearing also necessarily has a larger outer diameter. Therefore, in the structure of this multi-stage rotary indexing device, it becomes a form in which the above-mentioned large-diameter bearing retainer exists at the position on the drive shaft of each rotary indexing unit. Moreover, regarding the position of the bearing cage on the drive shaft, in each rotary indexing unit, a disk-shaped driven member with a larger outer diameter exists in a form that meshes with the drive member provided on the drive shaft. Therefore, the position of the above-mentioned large-diameter bearing cage on the drive shaft interferes with the driven member at a position closer to the drive member, and thus has to be a position away from the drive member where such interference does not occur. That is, the support of the drive shaft on the above-mentioned one end side is carried out at a position away from the drive member compared with the other end side. Based on this, the drive shaft in one of the rotary indexing units is connected to the drive shaft in the other adjacent rotary indexing unit on the above-mentioned one end side, but the connection position is of course outside the support position on the above-mentioned one end side (the side opposite to the drive member side). Thus, in one of the rotary indexing units, the distance from the drive member to the connection position on the above-mentioned one end side is necessarily large. As a result, in the conventional multi-stage rotary indexing device, the interval between the two rotary indexing units becomes large, and there is a problem that the entire device becomes large. In view of the above problems, an object of the present invention is to provide a structure, that is, in the above-mentioned multi-stage rotary indexing device, especially in a dual-stage rotary indexing device having two sets of rotary indexing units, it is possible to reduce the interval between the two sets of rotary indexing units in the axial direction of the drive shaft and make the entire device small. [Means for Solving the Problem] The present invention is premised on a dual-stage rotary indexing device, which includes two sets of rotary indexing units. The rotary indexing unit includes: a main shaft that is mounted with a rotation object member on one end side and is supported in a frame so as to be rotatable; and a drive transmission mechanism that transmits the rotation of the output shaft of a drive motor to the main shaft. The drive transmission mechanism includes: a drive shaft that is rotationally driven by a drive motor; a disk-shaped driven member that is mounted on 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. The drive shaft is supported by the frame via a bearing cage internally装有 a thrust bearing on one side of one end, and is supported by the frame via a radial bearing on one side of the other end. The drive shafts of the two rotary indexing units are connected by a connecting member, and the drive motor is connected to the end of the drive shaft in one of the rotary indexing units on the side opposite to the connecting member side. Based on this, the dual-stage rotary indexing device according to the present invention is characterized in that the other end of the drive shaft in one of the rotary indexing units is connected to the other end of the drive shaft in the other rotary indexing unit. [Effect of the Invention] It should be noted that the text contains some Chinese characters that may be incorrect or incomplete in the "装有" part. It might be a typo. If this is a specific technical term, it needs to be further verified.According to the present invention, in the above-described dual rotary indexing device under the premise, the dual rotary indexing device is configured such 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. In this way, each rotary indexing unit is arranged in the device in a state where one side of the end of the drive shaft supported by the thrust bearing is on the outer side in the axial direction with respect to the connection position connecting the two drive shafts. Therefore, in this structure, the bearing retainer provided to support the drive shaft in each rotary indexing unit is provided on the outer side with respect to each drive member, that is, in a form existing at a position on the side opposite to the connection position side with respect to the drive member. Moreover, the connection between the two rotary indexing units is in a form that is carried out between the radial bearings that support the other end side of each drive shaft. In addition, since the outer diameter of the radial bearing is smaller than the outer diameter of the thrust bearing, and a bearing retainer is not required for installation as in the case of the thrust bearing, the position on the drive shaft can be made closer to the drive member. In this way, compared with the above-described conventional structure, a structure can be achieved in which the above connection position is closer to the two drive members. Therefore, according to this structure, the interval between the two rotary indexing units can be reduced in the above axial direction, and thus the overall device can be made smaller. Hereinafter, based on the drawings, an embodiment (example) of the dual rotary indexing device to which the present invention is applied will be described. FIGS. 1 to 3 show a dual rotary indexing device 1 to which the present invention is applied. In addition, the illustrated dual rotary indexing device 1 is a so-called horizontal dual rotary indexing device in which the axis of the main shaft is set in the vertical direction. The dual rotary indexing device 1 includes: a frame 2 that is installed on a machine tool; two sets of rotary indexing units 10, 10 that are provided in the frame 2; and a drive motor 3 that is used to rotationally drive each rotary indexing unit 10. In addition, the two sets of rotary indexing units 10, 10 have substantially the same structure. Therefore, hereinafter, only one of the two sets of rotary indexing units 10, 10 will be described, and the description of the other will be omitted. As shown in FIGS. 2 and 3, the rotary indexing unit 10 includes: a main shaft 11 that is supported in the space within the frame 2 so as to be rotatable with respect to the frame 2; and a worktable 12 as a rotation target member that is installed on one end side of the main shaft 11. And, the rotary indexing unit 10 includes: a drive transmission mechanism 30 that is used to transmit the rotation of the output shaft of the drive motor 3 to the main shaft 11; and a clamping device 18 that is used to hold (clamp) the main shaft 11 at the indexed angular position. More specifically, the main shaft 11 is supported by bearings 14 within the space in the frame 2 in a state where its axis is oriented in the vertical direction so as to be rotatable relative to the frame 2. Further, the worktable 12 is a disk-shaped member for mounting a workpiece to be machined or the like, and at one end of the main shaft 11, it is mounted in a state where its end face abuts by a plurality of mounting bolts (not shown) so as not to be relatively rotatable relative to the main shaft 11. Moreover, regarding the drive transmission mechanism 30, in this embodiment, a so-called worm and worm gear mechanism including a disk-shaped worm gear and a worm directly engaged with the worm gear is adopted as an example of the drive transmission mechanism 30. More specifically, regarding this worm and worm gear mechanism (drive transmission mechanism) 30, the worm and worm gear mechanism 30 is composed of the following members: a drive shaft 33 that is rotationally driven by a drive motor 3; a disk-shaped worm gear 35 as a driven member that is mounted on the main shaft 11; and a worm 34 as a driving member that is provided on the drive shaft 33. The worm gear 35 is mounted in the above space of the frame 2 so as not to be relatively rotatable relative to the main shaft 11. In addition, the worm gear 35 is composed of the following members: a shaft-shaped shaft portion that is mounted on the main shaft 11; and a flange portion that is formed as a flange-shaped portion protruding in the radial direction from the shaft portion, that is, having helical teeth formed on the outer peripheral surface. Moreover, the worm gear 35 is arranged such that in the axial direction of the main shaft 11, the flange portion is located at approximately the central portion of the main shaft 11. Furthermore, the drive shaft 33 is arranged in the frame 2 in a form where its axis is oriented in the horizontal direction (a direction orthogonal to the axis of the main shaft 11). Therefore, in the frame 2, a hole for accommodating the drive shaft 33, that is, an accommodation hole 25, is provided, and the accommodation hole 25 is formed to communicate with the above space and penetrate the frame 25 in the horizontal direction. In addition, the accommodation hole 25 is formed as a hole having a diameter larger than the thickness dimension of the above flange portion of the worm gear 35. Moreover, the accommodation hole 25 is formed in a position in the axial direction of the main shaft 11 that includes the existence range of the above flange portion. And the drive shaft 33 is supported in the accommodation hole 25 via bearings so as to be rotatable relative to the frame 2. Based on this, a worm 34 is provided on the drive shaft 33 thus supported in the accommodation hole 25. In addition, the worm 34 is provided at approximately the central portion of the drive shaft 33. Moreover, as is well known, the worm 34 is a gear having helical teeth formed on its outer periphery and has a helical groove formed by the teeth on its outer peripheral surface. And in a state where the worm 34 is provided on the drive shaft 33 like this, it becomes a state where the groove meshes with the helical teeth of the flange portion in the worm gear 35. Moreover, in the present embodiment, the worm 34 is a so-called multi-lead type worm in which the lead is slightly different on the left and right sides of the tooth surface and the thickness dimension of the tooth gradually increases toward one side in the axial direction of the drive shaft 33. As is well known, the worm and worm gear mechanism 30 including such a multi-lead type worm 34 adjusts the backlash between the worm 34 and the flange portion of the worm gear 35 by displacing the worm 34 in the axial direction of the drive shaft 33. Moreover, in the dual rotary indexing device 1 in which the rotary indexing unit 10 has the above structure, the two sets of rotary indexing units 10, 10 are arranged in the frame 2 in a form arranged in the axial direction with the axes of the two drive shafts 33, 33 coinciding when observed in the axial direction. On this basis, 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 as a connecting member. Moreover, after the connection of the drive shafts 33, 33, a drive motor 3 for driving the drive shafts 33, 33 is connected. More specifically, a bottomed hole, that is, a hole 26, which opens in one of the two side surfaces of the housing hole 25, is formed in the frame 2, and the output shaft of the drive motor 3 is accommodated in the hole 26. In addition, the hole 26 is formed to be located above the housing hole 25 and partially overlap with the housing hole 25 when observed in the axial direction of the drive shaft 33. And, on the above-mentioned one side surface of the frame 2, a plate-shaped motor bracket 27 is installed in a form to block the opening of the housing hole 25 and the opening of the hole 26. In addition, a through hole is formed through the motor bracket 27 at a position communicating with the hole 26. On this basis, the drive motor 3 is installed on the motor bracket 27 in a form that the output shaft is accommodated in the hole 26 through the through hole of the motor bracket 27. And, a pinion 31 is installed on the output shaft of the drive motor 3. On the other hand, on the drive shaft 33 on the drive motor 3 side among the two drive shafts 33, 33 connected as described above, a driven gear 32 that meshes with the pinion 31 is installed at the end on the side opposite to the coupling 5 (connecting member) side (drive motor 3 side). Thus, the two drive shafts 33, 33 are in a state where the end of the drive shaft 33 in one (drive motor 3 side) rotary indexing unit 10 on the side opposite to the connecting member side is connected to the drive motor 3 via the driven gear 32 and the pinion 31. Moreover, as described above, each rotary indexing unit 10 includes: a clamping device 18 for holding the spindle 11 at the angular position indexed as a result of the two drive shafts 33, 33 being rotationally driven by the connected drive motor 3. In addition, in the illustrated example, the clamping device 18 is a so-called disk-type clamping device. Specifically, the clamping device 18 includes: a clamping disk 15 mounted on the spindle 11 side; and a clamping piston 16 pressing the clamping disk 15 against the clamping surface provided on the frame 2. The clamping device 18 supplies a working fluid to the pressure chamber 17 defined by the clamping piston 16 and the frame 2, and the clamping disk 15 is clamped by the pressure of the working fluid between the clamping piston 17 and the clamping surface, bringing it into a state (clamped state) where the spindle 11 is held. In the dual rotary indexing device 1 described above, in the present invention, the drive shaft 33 of each rotary indexing unit 10 is supported by the frame 2 via a thrust bearing on one side of one end, and is supported by the frame 2 via a radial bearing on one side of the other end. Among them, the thrust bearing that supports the drive shaft 33 on one side of one end is provided in the form of being internally mounted in a bearing cage, and is mounted on the frame 2 via this bearing cage. On this basis, in the present invention, the dual rotary indexing device 1 is configured such that the two rotary indexing units 10, 10 are arranged in a form in which 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. Hereinafter, an embodiment (example) of such a dual rotary indexing device 1 will be described in detail. In the dual rotary indexing device 1, each rotary indexing unit 10 is configured such that the drive shaft 33 is supported by the frame 2 via a thrust bearing 41 on one side of one end 33a as described above, and is supported by the frame 2 via a radial bearing 43 on one side of the other end 33b. In addition, in this embodiment, the thrust bearing 41 is an angular contact ball bearing, and the radial bearing 43 is a roller bearing. And, in this dual rotary indexing device 1, as described above, the two rotary indexing units 10, 10 are arranged in a form in which the end on the other end 33b side of the drive shaft 33 in one rotary indexing unit 10 is connected to the end on the other end 33b side of the drive shaft 33 in the other rotary indexing unit 10. Therefore, one (the right side in FIG. 1) rotary indexing unit 10 is configured such that one side (the drive motor 3 side) of the two sides where the storage hole 25 in the frame 2 opens is on the one end 33a side of the drive shaft 33; the other (the left side in FIG. 1) rotary indexing unit 10 is configured such that one side (the side opposite to the drive motor 3 side) of the above two sides is on the one end 33a side of the drive shaft 33. Therefore, in each of the rotary indexing units 10, the position where the angular contact ball bearing 41 that supports the end portion on the one end 33a side of the drive shaft 33 is provided becomes the corresponding end portions in the storage holes 25 of the frame 2. On this basis, at the end portions of the storage holes 25, the angular contact ball bearing 41 of the drive shaft 33 is provided in a form that is internally fitted in the bearing cage 40 and is mounted on the frame 2 via the bearing cage 40. That is, each drive shaft 33 is supported by the frame 2 at the end portions of the storage holes 25 via the bearing cage 40 in which the angular contact ball bearing 41 is internally fitted on one side of the one end 33a. Each of these bearing cages 40 is a hollow cylindrical member having a through hole 40d in the center in which the angular contact ball bearing 41 is internally fitted. And, the bearing cage 40 is formed such that the outer diameter of the portion on one end side in the axial direction is larger than the outer diameter of the other portions. That is, the bearing cage 40 is configured to be composed of the large-diameter portion 40b on the above-mentioned one end side and the main body portion 40a of the portions other than the large-diameter portion 40b. In contrast, the storage holes 25 are formed to have enlarged-diameter portions 25b at both ends with a hole diameter larger than that of the other portions. And, in the storage holes 25, the portion (storage portion) 25a for storing the worm 34 and the portion (communication portion) 25c communicating with both of them between the storage portion 25a and the enlarged-diameter portion 25b need to have a hole diameter larger than or equal to the outer diameter of the worm 34 so that the worm 34 can be inserted into the storage portion 25a from the outside. In the illustrated example, the hole diameter is the same as the hole diameter of the storage portion 25a. On this basis, the large-diameter portion 40b in the bearing cage 40 is formed such that the outer diameter is substantially the same as the hole diameter of the enlarged-diameter portion 25b in the storage hole 25. And, the main body portion 40a is formed such that the outer diameter is substantially the same as the hole diameter of the communication portion 25c in the storage hole 25. Moreover, each bearing cage 40 is provided in a form that the large-diameter portion 40b side faces the opening side (outer side) of the storage hole 25 and the main body portion 40a is inserted into the communication portion 25c with respect to the corresponding end portions in the storage hole 25. In addition, internal threads are formed on the inner peripheral surface of each enlarged-diameter portion 25b in the storage hole 25. On the other hand, external threads are formed on the outer peripheral surface of the large-diameter portion 40b in each bearing cage 40. Thus, each bearing cage 40 is mounted on the frame 2 in a form that the external threads of the large-diameter portion 40b are threadedly engaged with the internal threads of the enlarged-diameter portion 25b of the storage hole 25. And, according to this structure, by rotating the bearing cage 40 (the external threads of the large-diameter portion 40b) with respect to the frame 2 (the internal threads of the enlarged-diameter portion 25b), the position of the bearing cage 40 with respect to the frame 2 can be changed in the axial direction of the drive shaft 33. On this basis, in the frame 2, there are formed: internal threaded holes 42a, which are respectively opened at the communication portions 25c in the storage holes 25, and are penetrated and provided in a manner of horizontally penetrating from the rear surface of the frame 2 toward the storage holes 25. And, a stop threaded member 42b is threadedly inserted into each of these internal threaded holes 42a. Moreover, by pressing each of these stop threaded members 42b against the outer peripheral surface of the main body portion 40a of the bearing cage 40 inserted into the communication portion 25c as described above, the positions of the respective bearing cages 40 relative to the frame 2 are fixed. In addition, for each of the bearing cages 40 thus mounted on the frame 2, angular contact ball bearings 41 are internally mounted as described above. In the illustrated example, two of these angular contact ball bearings 41 are provided in the through holes 40d. And, in each of the through holes 40d, the two angular contact ball bearings 41, 41 are arranged at intervals in a direction facing each other. And, regarding the roller bearing 43 used for supporting one side of the other end 33b of the drive shaft 33, the roller bearing 43 is a bearing specifically for bearing loads in the radial direction. Therefore, the roller bearing 43 is arranged on one side of the other end 33b in a state of being directly fitted into the storage hole 25 and allowing displacement in the axial direction. In addition, as described above, the bearing cage 40 internally mounting the angular contact ball bearing 41 for supporting one end 33a side of the drive shaft 33 is arranged in a state capable of displacing relative to the frame 2 in the axial direction of the drive shaft 33. And, the roller bearing 43 for supporting the other end 33b side of the drive shaft 33 is arranged in a state allowing displacement in the axial direction. Thus, in the worm gear mechanism 30 of the multi-lead worm 34 as described above, by displacing the bearing cage 40 relative to the frame 2 in the axial direction of the drive shaft 33, the worm 34 can be displaced relative to the worm wheel 35 in the axial direction of the drive shaft 33 to adjust the above-mentioned backlash. And, as described above, the worm 34 stored in the storage hole 25 (storage portion 25a) is set to mesh with the worm wheel 35 provided in the above-mentioned space of the frame 2, and the storage hole 25 is formed to communicate the storage portion 25a with the above-mentioned space. Moreover, this communication is performed by forming an opening extending in the axial direction of the drive shaft 33 in the storage portion 25a. Thus, in the storage hole 25, a part of the storage portion 25a overlaps with a part of the above-mentioned space in the axial direction of the drive shaft 33, and a part of the disk-shaped worm wheel 35 intrudes into the storage portion 25a in the radial direction through the above-mentioned opening. On this basis, the roller bearing 43 is disposed within the housing hole 25 and in a portion (the fitting portion) 25d on the side opposite to the communication portion 25c with respect to the housing portion 25a, and is arranged in such a manner that it is directly inserted into the housing hole 25 (the fitting portion 25d) as described above. However, generally, the outer diameter of the roller bearing 43 is smaller than the outer diameter of the angular contact ball bearing 41 used for supporting one end 33a side of the drive shaft 33 described above. Therefore, the fitting portion 25d in the housing hole 25 is formed to have a smaller hole diameter than the housing portion 25a and the communication portion 25c. In addition, the fitting portion 25d and the communication portion 25c are portions that are continuous (communicate) with the housing portion 25a on both sides of the housing portion 25a as described above. And, the fitting portion 25d is formed to have a smaller hole diameter than the communication portion 25c. Therefore, in the relationship between the fitting portion 25d and the worm gear 35 that intrudes into the housing portion 25a as described above, the fitting portion 25d can be formed at a position closer to the worm 34 than the communication portion 25c. Therefore, in the rotary indexing unit 10, the fitting portion 25d is formed at a position closer to the worm 34 than the communication portion 25c. Thus, the position of the roller bearing 43 disposed in the fitting portion 25d, that is, the supporting position of the roller bearing 43 on the other end 33b side of the drive shaft 33 becomes a position closer to the worm 34 than the supporting position of the angular contact ball bearing 41 on the one end 33a side of the drive shaft 33. In this way, in the two rotary indexing units 10, 10 of the dual rotary indexing device 1, the drive shaft 33 is arranged in such a manner that the other end 33b side based on the roller bearing 43 is supported at a position closer to the worm 34 than the one end 33a side based on the angular contact ball bearing 41 (bearing cage 40). Moreover, concomitantly, the drive shaft 33 in each rotary indexing unit 10 is formed such that, with respect to the distance from the worm 34 to the shaft end on the drive shaft 33, the other end 33b side is shorter than the one end 33a side. On this basis, as described above, the dual rotary indexing device 1 is configured such that the other end 33b side of the drive shaft 33 in one rotary indexing unit 10 is connected to the other end 33b side of the drive shaft 33 in the other rotary indexing unit 10. Therefore, according to this structure, for example, compared with a dual rotary indexing device in which the drive shaft 33 in one rotary indexing unit 10 is connected to the drive shaft 33 (the other end 33b) in the other rotary indexing unit 10 on the one end 33a side, the distance from the position of the worm 34 to the connection position of the two drive shafts 33, 33 in this one rotary indexing unit 10 is shorter. In addition, in the rotary indexing unit 10, in the axial direction of the drive shaft 33, the position of the worm 34 corresponds to the position of the main shaft 11. Therefore, as described above, the distance from the position of the worm 34 in one rotary indexing unit 10 to the connection position of the two drive shafts 33, 33 becomes shorter, and thus the interval between the two main shafts 11, 11 in the双联 rotary indexing device 1 becomes smaller. Therefore, according to such a structure, it is possible to minimize the interval between the two rotary indexing units 10, 10 in the axial direction of the drive shaft 33, and thus the entire双联 rotary indexing device 1 can be made smaller. As described above, an embodiment of the双联 rotary indexing device of the present invention has been described. However, the双联 rotary indexing device of the present invention is not limited to the above embodiment, and can also be implemented by the following modified examples. (1) Regarding the drive transmission mechanism, in the above embodiment, as the drive transmission mechanism for transmitting the rotation of the output shaft of the drive motor 3 to the main shaft 11, a worm and worm gear mechanism 30 composed of a worm gear 35 and a worm 34 was adopted. And, in the above embodiment, the worm 34 in the worm and worm gear mechanism 30 adopted a multi-lead worm. However, in the present invention, even when a worm and worm gear mechanism is adopted as the drive transmission mechanism, the worm is not limited to the multi-lead worm of the above embodiment, and may also be a so-called single-lead worm formed with a constant tooth thickness dimension in the axial direction of the drive shaft 33. In addition, when the worm is a single-lead worm, even if the worm is displaced in the axial direction of the drive shaft 33, the backlash between the worm and the worm gear cannot be adjusted, and thus the双联 rotary indexing device may not be configured such that the drive shaft can adjust its position in the axial direction as in the above embodiment. Therefore, in this case, the bearing cage may also be set so as not to be able to change the position in the axial direction of the drive shaft. That is, the双联 rotary indexing device may also be configured such that the bearing cage is provided in a form fixed to a specific position. And, the drive transmission mechanism is not limited to a form in which the worm as the drive member directly engages with the worm gear as the driven member in a spiral groove as in the worm and worm gear mechanism of the above embodiment, and may also be other forms of drive transmission mechanisms in which the drive member indirectly engages with the driven member in a spiral groove. Specifically, the drive transmission mechanism may also be a so-called ball drive mechanism in which the worm gear and the worm are connected via steel balls. And, the drive transmission mechanism may also be a so-called roller wheel cam mechanism in which a turret wheel having a plurality of roller followers mounted thereon at intervals on the outer periphery and a roller wheel cam having a spiral cam groove corresponding to the rollers of the roller followers are connected. In addition, in the case of this roller wheel cam mechanism, the turret wheel corresponds to the driven member, and the roller wheel cam corresponds to the drive member. (2) Regarding the frame of the dual rotary indexing device, in the above embodiment, the dual rotary indexing device 1 is configured such that the frame 2 for arranging two sets of rotary indexing units 10, 10 is an integrally formed member. However, the dual rotary indexing device is not limited to being configured such that the frame is formed in this way, and it may also be configured to form the frame by combining (connecting) two members that respectively arrange two sets of rotary indexing units. Further, in this case, through holes that become storage holes when combined are formed in each member for forming the frame, and one of the side surfaces (the surface where the through hole opens) of the two members is formed as a connection surface orthogonal to the through direction of the storage hole (parallel to the axis of the main shaft). On this basis, the two members are combined in a state where the connection surfaces are in contact with each other to form the frame. (3) Regarding the dual rotary indexing device which is a prerequisite for the present invention, in the above embodiment, the dual rotary indexing device 1 is a so-called horizontal dual rotary indexing device in which the axis of the main shaft is set in the vertical direction. However, the dual rotary indexing device to which the present invention is applied is not limited to such a horizontal dual rotary indexing device, and it may also be a so-called vertical dual rotary indexing device in which the axis of the main shaft is set in the horizontal direction. And, the dual rotary indexing device to which the present invention is applied is not limited to being set in a form in which the above-mentioned frame is directly mounted on a machine tool. For example, the present invention may also be applied to the rotary indexing part of a so-called inclined rotary indexing device having two types of rotary indexing parts, namely an inclined indexing part and a rotary indexing part. In addition, the present invention is not limited to any of the above-described embodiments, and can be appropriately changed without departing from the gist. 1: Dual rotary indexing device 2: Frame 3: Driving motor 5: Coupling (connecting member) 10: Rotary indexing unit 11: Main shaft 12: Workbench (rotating object member) 14: Bearing 15: Clamping disk 16: Clamping piston 17: Pressure chamber 18: Clamping device 25: Storage hole 25a: Storage part 25b: Diameter-expanded part 25c: Communication part 25d: Fitting part 26: Hole 27: Motor bracket 30: Worm and worm gear mechanism (driving transmission mechanism) 31: Small gear 32: Driven gear 33: Driving shaft 33a: One end 33b: The other end 34: Worm (driving member) 35: Worm gear (driven member) 40: Bearing retainer 40a: Main body part 40b: Large-diameter part 40d: Through hole 41: Angular contact ball bearing (thrust bearing) 42a: Internal thread hole 42b: Stopping threaded member 43: Roller bearing (radial bearing) [Fig. 1] is a top cross-sectional view showing the dual rotary indexing device to which the present invention is applied. [Fig. 2] is a sectional view taken along line A-A of Fig. 1 (side cross-sectional view). [Fig. 3] is an enlarged view of the main part of Fig. 1. 1: Dual rotary indexing device 2: Frame 3: Drive motor 5: Coupling (connecting member) 10: Rotary indexing unit 11: Spindle 25: Storage hole 25a: Storage part 25b: Diameter-expanded part 25c: Communication part 25d: Fitting part 26: Hole 27: Motor bracket 30: Worm and worm gear mechanism (drive transmission mechanism) 31: Pinion 32: Driven gear 33: Drive shaft 33a: One end 33b: The other end 34: Worm (drive member) 35: Worm gear (driven member) 40: Bearing cage 40a: Main body part 40b: Large-diameter part 40d: Through hole 41: Angular contact ball bearing (thrust bearing) 42a: Internal thread hole 42b: Locking thread part 43: Roller bearing (radial bearing)

Claims

1. A double-rotary indexing device comprising two sets of rotary indexing sections; each rotary indexing section includes: a main shaft, on which a rotating object component is mounted at one end and supported within a frame to be rotatable; and a drive transmission mechanism for transmitting rotation of the output shaft of a drive motor to the main shaft; the drive transmission mechanism includes: a drive shaft, driven by the drive motor; a disc-shaped driven component mounted on the main shaft; and a drive component having a helical groove that directly or indirectly engages with the driven component and disposed on the drive shaft; the drive shaft is supported at one end by the frame via a bearing cage containing a thrust bearing, and at the other end by the frame via a radial bearing; the drive shafts of the two rotary indexing sections are connected by a connecting member, and the drive motor is connected to the end of the drive shaft in one of the rotary indexing sections opposite to the side of the connecting member; The aforementioned double rotary indexing device is characterized in that: the other end of the aforementioned drive shaft in the rotary indexing section of one of the aforementioned devices is connected to the other end of the aforementioned drive shaft in the rotary indexing section of the other device.

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