Rotary indexing apparatus for machine tool

Abstract

To provide a rotary indexing apparatus capable of reducing the overall production cost in production in a production factory that produces a large variety of rotary indexing apparatuses and produces the rotary indexing apparatuses that employ a partially unitized clamp device.SOLUTION: In a rotary indexing apparatus for a machine tool, a clamp device includes a clamp piston and a housing detachably provided on a frame, and is configured to supply a working fluid to a pressure chamber formed between the housing and the clamp piston. The clamp device is a hydraulic clamp device using hydraulic oil as the working fluid, or a pneumatic clamp device using compressed air. The frame includes both a hydraulic oil supply passage for supplying hydraulic oil to the hydraulic clamp device and a compressed air supply passage for supplying compressed air to the pneumatic clamp device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary indexing device for a machine tool, comprising: a frame having an accommodation hole formed therethrough, the frame rotatably supporting a spindle within the accommodation hole; a clamp disc attached to the spindle so as not to be rotatable relative to the spindle; and a clamp device that clamps the clamp disc in cooperation with the frame, the clamp device including a clamp piston pressed against the clamp disc, and a housing configured to slide and guide the clamp piston in a clamping direction and removably provided on the frame with the clamp piston accommodated in the accommodation hole; and the clamp device configured to supply a working fluid to a pressure chamber formed between the housing and the clamp piston in the clamp device. [Background technology]

[0002] In a machine tool, a spindle having a driven member such as a circular table on which a workpiece is placed attached at one end is rotatably supported on a frame, and the spindle is rotationally driven by a drive mechanism, and a rotation indexing device is used in which the angular position of the spindle is clamped by a clamping device to index the angular position. A clamp disc is attached to the spindle so as not to rotate relative to it, and the clamping device is configured to apply a clamping force to the spindle by pressing a clamp piston against the clamp disc in cooperation with a clamping surface formed on the frame.

[0003] Furthermore, as a clamp device for such a rotary indexing device, there is one disclosed in Patent Document 1, in which the parts excluding the clamp disc are unitized and the unitized part is configured to be attachable to and detachable from the frame for maintenance, etc. Specifically, the clamp device is configured to include a clamp piston that is pressed against the clamp disc and a housing (case member) configured to guide the sliding of the clamp piston in the clamping direction (the direction in which the clamp piston applies a pressing force to the clamp disc). The housing is attached to the frame with the clamp piston housed in an accommodating hole formed through the frame and in which the main shaft is rotatably supported, and is configured to be detachable from the frame.

[0004] Clamping devices for rotary indexing devices include hydraulic clamping devices that use hydraulic oil as the working fluid, and pneumatic clamping devices that use compressed air as the working fluid. This also applies to clamping devices in which part of the device is unitized (unit type), such as the configuration of Patent Document 1. Incidentally, which of the hydraulic clamping device and the pneumatic clamping device is used for the rotary indexing device is determined depending on the magnitude of the torque (clamping force) required for clamping and the equipment in the factory. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-018392 Summary of the Invention [Problem to be solved by the invention]

[0006] The frame of the rotary indexing device is provided with a supply passage for supplying hydraulic fluid to the pressure chamber of the clamping device, and the supply passage is generally formed with a different inner diameter depending on whether the clamping device is a hydraulic clamping device or a pneumatic clamping device.

[0007] Specifically, when the clamping device is a pneumatic clamping device, the working fluid, air, is compressible. As the air is supplied, the air in the space including the pressure chamber and the supply passage leading to the pressure chamber is compressed, increasing its pressure, thereby achieving the desired clamped state. Therefore, for a given pressure chamber, if the inner diameter of the supply passage is large (the volume of the space within the supply passage is large), the rate at which the pressure in the entire space increases slows, resulting in a longer time until the clamped state is achieved. In other words, the responsiveness from the start of the supply of the working fluid (air) until the clamped state is achieved deteriorates. Furthermore, this poor responsiveness may adversely affect machining efficiency and machining accuracy. Therefore, when the clamping device is a pneumatic clamping device, it is generally considered to design the inner diameter of the supply passage as small as possible, taking the responsiveness into consideration.

[0008] In contrast, when the clamping device is a hydraulic clamping device, the hydraulic fluid, oil, is an incompressible fluid and does not increase in pressure to the level required to achieve the clamped state through compression, as is the case with air. Therefore, the inner diameter of the supply passage has little effect on the responsiveness. In other words, in the case of a hydraulic clamping device, the desired responsiveness can be achieved even if the inner diameter of the supply passage is large. Hydraulic clamping devices are often used when a large clamping force is required. Furthermore, in the case of a hydraulic clamping device, the larger the inner diameter of the supply passage, the greater the pressure transmitted and the greater the clamping force obtained. Therefore, it is generally considered to design the inner diameter of the supply passage to be as large as possible.

[0009] For these reasons, conventionally, the supply passage formed in the frame is generally designed to have a different inner diameter depending on whether the clamping device is a hydraulic clamping device or a pneumatic clamping device. Therefore, different frames are manufactured depending on whether the clamping device is a hydraulic clamping device or a pneumatic clamping device. However, for a manufacturing factory that manufactures a large number of rotary indexing devices, manufacturing different frames in this way increases the total manufacturing cost compared to when there is only one type of frame (when the rotary indexing devices manufactured are either those that use hydraulic clamping devices or those that use pneumatic clamping devices).

[0010] Furthermore, in the case of a rotary indexing device that employs a unit-type clamping device as described above, the clamping device is retrofitted to the frame, so the frame is designed without including any part of the clamping device. However, even in this case, the frame is manufactured separately, just as in the case of a rotary indexing device in which the clamping device is incorporated into the frame from the beginning (part of the frame forms part of the clamping device). Therefore, even if the rotary indexing device employs a unit-type clamping device, the manufacturing factory will still be in a situation where the manufacturing costs increase.

[0011] Therefore, the present invention aims to provide a rotary indexing device configured to reduce the total manufacturing costs in terms of production compared to conventional methods in a manufacturing factory that manufactures a large number of rotary indexing devices, including rotary indexing devices that employ a partially unitized clamping device. [Means for solving the problem]

[0012] The present invention is based on a rotary indexing device for a machine tool, which includes a frame having an accommodation hole formed therethrough, the frame rotatably supporting a spindle within the accommodation hole, a clamp disc attached to the spindle so as not to be rotatable relative to the spindle, and a clamp device which clamps the clamp disc in cooperation with the frame, the clamp device including a clamp piston pressed against the clamp disc, and a housing configured to slide and guide the clamp piston in a clamping direction and removably provided on the frame with the clamp piston accommodated in the accommodation hole, and the clamp device configured to supply working fluid to a pressure chamber formed between the housing and the clamp piston in the clamp device.

[0013] Furthermore, the present invention is characterized in that the clamp device is a hydraulic clamp device that uses hydraulic oil as the working fluid or a pneumatic clamp device that uses compressed air as the working fluid, and the frame is configured to be able to mount either the hydraulic clamp device or the pneumatic clamp device, and has both a hydraulic oil supply path for supplying the hydraulic oil to the hydraulic clamp device and a compressed air supply path that is a supply path separate from the hydraulic oil supply path and for supplying the compressed air to the pneumatic clamp device. [Effects of the Invention]

[0014] According to the present invention, in a rotary indexing device that employs a unit-type clamping device, the frame is formed with both a hydraulic oil supply path for a hydraulic clamping device and a compressed air supply path for a pneumatic clamping device, making it possible to use the frame in both cases where a hydraulic clamping device and a pneumatic clamping device are employed as the clamping device. This eliminates the need for manufacturing different frames depending on the clamping device employed, as in the past, and in terms of total production costs, the manufacturing costs can be reduced to a level similar to that of manufacturing only one type of frame. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a plan view showing a circular table device to which the present invention is applied. [Figure 2] A partial cross-sectional view taken along line AA in Figure 1. [Figure 3] FIG. 2 is an enlarged view of a main part of the cross section taken along line AA in FIG. 1 in an example in which a hydraulic clamping device is used. [Figure 4] FIG. 2 is an enlarged view of a main part of the cross section taken along line BB in FIG. 1 in an example in which a pneumatic clamping device is used. [Figure 5] 2 is an enlarged view of a main portion of a cross section taken along line ACB in FIG. 1 in an example in which another type of clamping device is used. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a rotary indexing device for a machine tool according to the present invention will be described below with reference to Figures 1 to 5. The example described below is an example in which the present invention is applied to a circular table device as a rotary indexing device. The circular table device in the illustrated example is a so-called horizontal circular table device in which the axis of the main spindle is oriented vertically.

[0017] 1 and 2, the circular table device 1 is mainly composed of a frame 10. The frame 10 has a receiving hole 11 formed therein, which penetrates from the top to the bottom. In the circular table device 1, a main shaft 12 is rotatably supported within the receiving hole 11 relative to the frame 10 via a bearing 20. A disk-shaped circular table 14, on which a workpiece or the like is attached, is fixed to one end of the main shaft 12 (the upper surface side of the frame 10).

[0018] The circular table device 1 also includes a drive mechanism 16 for driving the main shaft 12 to rotate, the drive mechanism 16 having a drive motor M as its drive source. As shown in FIG. 1, the drive motor M is attached to the side surface of the frame 10. The drive mechanism 16 also includes a worm gear mechanism as a drive transmission mechanism for transmitting the rotation of the output shaft of the drive motor M to the main shaft 12. The worm gear mechanism is made up of a worm wheel 24 fixed to the main shaft 12 and a worm shaft 26 that includes a worm meshing with the worm wheel 24 and is rotatably supported on the frame 10 with its axis perpendicular to that of the main shaft 12. The worm shaft 26 is connected to the output shaft of the drive motor M.

[0019] The circular table device 1 also includes a clamp disc 28 that is clamped by the frame 10 in cooperation with a clamp device (described later) to fix the angular position of the main shaft 12 (circular table 14) that has been rotated and indexed by the drive mechanism 16. The clamp disc 28 is fixed by bolts or the like to the end face of the worm wheel 24 that faces the bottom side of the frame 10. Therefore, the clamp disc 28 is assembled to the main shaft 12 via the worm wheel 24 so as not to be able to rotate relative to it.

[0020] The clamp disc 28 has a diameter dimension such that its outer peripheral edge is positioned close to the inner peripheral surface of the accommodating hole 11. On the other hand, the frame 10 is formed with a smaller diameter in the up-down direction at the portion above the position where the clamp disc 28 is provided than at the portion below, forming a step within the accommodating hole 11. Therefore, the clamp disc 28, at its outer peripheral portion, faces the surface 10a of the step within the accommodating hole 11 that faces the bottom surface.

[0021] Then, the clamp piston in the clamp device is pressed against the clamp disc 28, and the clamp disc 28 is sandwiched between the surface 10a and the clamp piston, thereby preventing the rotation of the clamp disc 28. Therefore, the surface 10a of the frame 10 serves as a clamp surface for clamping the clamp disc 28. With the clamp disc 28 clamped in this manner, the angular position of the spindle 12 is fixed.

[0022] Such a rotary table apparatus 1 is equipped with a hydraulic clamping device that uses hydraulic oil as the working fluid or a pneumatic clamping device that uses compressed air as the working fluid as the clamping device. In the present invention, the clamping device is structurally unitized and detachable from the frame.

[0023] Each clamping device will be described in detail below with reference to the drawings. Fig. 3 shows hydraulic clamping device H, and Fig. 4 shows pneumatic clamping device P. However, as shown in the drawings, in this embodiment, both clamping devices are configured in the same manner in most parts. Therefore, in the following description, structurally identical parts will be described together and will be assigned the same reference numerals in the drawings.

[0024] 3 and 4, the hydraulic clamping device H and the pneumatic clamping device P include a housing member 42 serving as a base, a clamp piston 40 inserted into the housing member 42, a compression spring 48 that biases the clamp piston 40, and a support member 46 that supports the compression spring 48. In this embodiment, the housing member 42 and the support member 46 constitute the housing of the present invention.

[0025] Of these, housing member 42 is configured as a cylindrical member having a through hole in the center. Housing member 42 is formed to have an outer diameter that is approximately the same as the inner diameter of the portion of accommodation hole 11 of frame 10 where clamp disc 28 is located. The through hole in housing member 42 is formed as a hole whose inner diameter is slightly larger than the outer diameter of spindle 12.

[0026] The housing member 42 has an annular groove 43 that opens to one end surface in the axial direction and is formed so that its center coincides with the center of the housing member 42 when viewed in the axial direction. The groove 43 is a groove (insertion groove) into which the clamp piston 40 is inserted. The housing member 42 also has a flange portion 44 formed on the other end in the axial direction so as to protrude radially outward. The accommodating hole 11 of the frame 10 is formed so that the portion on the bottom side of the frame 10 expands in diameter. The flange portion 44 is formed so that its outer diameter is approximately the same as the inner diameter of the expanded diameter portion of the accommodating hole 11. In the illustrated example, the thickness of the flange portion 44 is slightly smaller than the vertical dimension of the expanded diameter portion of the accommodating hole 11.

[0027] The clamp piston 40 is also configured as a cylindrical member with a through hole in the center. However, the clamp piston 40 has a disk-shaped guide portion 40b that is inserted into the insertion groove 43 of the housing member 42, and a pressing portion 40a that is formed on the outer periphery of the guide portion 40b and protrudes from the guide portion 40b in the thickness direction. The guide portion 40b and the pressing portion 40a of the clamp piston 40 are integrally formed, forming a member with a substantially L-shaped cross section. The clamp piston 40 is inserted into the insertion groove 43 of the housing member 42 at the guide portion 40b, and is provided so as to be slidably guided in the axial direction by the housing member 42.

[0028] Regarding the axial dimension of the clamp piston 40, the thickness of the guide portion 40b is slightly smaller than the depth of the insertion groove 43. Furthermore, the dimension of the pressing portion 40a in the protruding direction from the guide portion 40b is set so that its tip is positioned close to the clamp disc 28 when the clamp device is installed in the circular table device 1.

[0029] The support member 46 is also configured as a cylindrical member having a through hole in the center. The through hole in the support member 46 is formed so that its inner diameter is the same as the through hole in the housing member 42. The support member 46 is also formed so that its outer diameter is approximately the same as the inner diameter of the pressing portion 40a of the clamp piston 40.

[0030] Furthermore, the support member 46 is arranged so that its center coincides with the center of the housing member 42 when viewed in the axial direction, and is fixed to the housing member 42 with its end face abutting against the end face on the one end side of the housing member 42. The fixing is performed in such a way that the bolt 41 inserted through the support member 46 is screwed into the housing member 42.

[0031] By fixing the support member 46 to the housing member 42 in this manner, in the clamp device, the bottom surface (the end surface on the housing member 42 side) of the support member 46 faces the guide portion 40b of the clamp piston 40 in the axial direction, and the position of the guide portion 40b is restricted within the insertion groove 43 of the housing member 42 (the guide portion 40b is maintained housed within the insertion groove 43). Therefore, the housing member 42, the support member 46, and the clamp piston 40 are combined in a manner that allows them to be handled as a unit, and the clamp device consisting of these components is unitized.

[0032] The pressing portion 40a of the clamp piston 40 is formed in a shape in which its outer diameter is enlarged from a position slightly spaced from the guide portion 40b to the tip. The outer diameter of the enlarged portion is substantially the same as the outer diameter of the housing member 42 excluding the flange portion 44. Because the outer diameter is enlarged in this way, the pressing portion 40a has a stepped shape near the guide portion 40b.

[0033] Furthermore, the clamp piston 40 is formed so that a small gap exists between the guide portion 40b and the support member 46 in the axial direction when the end face of the stepped portion of the pressing portion 40a facing the housing member 42 abuts against the housing member 42. As a result, the clamp piston 40 is provided so that it can be displaced (slid) in the axial direction from the state in which its end face abuts against the housing member 42.

[0034] Furthermore, the clamp piston 40 is formed so that, when its end face abuts against the housing member 42, there is a small space between the guide portion 40b and the bottom surface of the insertion groove 43 in the housing member 42. The space 50 between the guide portion 40b of the clamp piston 40 and the bottom surface of the insertion groove 43 in the housing member 42 is a space to which working fluid is supplied via a supply path or the like, which will be described later, to press the clamp piston 40 toward the clamp disc 28. Therefore, the space 50 serves as a pressure chamber in the clamp device.

[0035] The support member 46 has a plurality of bottomed holes 46a that open to the bottom surface and are formed at equal intervals in the circumferential direction of the support member 46. A compression spring 48 is installed in each of the holes 46a. As a result, the clamp piston 40 is constantly urged toward the housing member 42 by the plurality of compression springs 48, and the end face of the pressing portion 40a is in contact with the housing member 42. Note that, of the hydraulic clamp device H and the pneumatic clamp device P, the hydraulic clamp device H has a greater number of compression springs 48.

[0036] According to the clamping devices (hydraulic clamping device H, pneumatic clamping device P) described above, due to the relationship between the outer diameters of the housing member 42 and clamping piston 40 in the clamping device and the inner diameter of the accommodation hole 11 in the frame 10, the clamping device can be inserted into the frame 10 (accommodating hole 11) with the outer surfaces of the housing member 42 and clamping piston 40 abutting (sliding) against the inner surface 11a of the accommodation hole 11. Then, in the circular table device 1, either the hydraulic clamping device H or the pneumatic clamping device P is inserted into the accommodation hole 11 of the frame 10 in this way, and is attached to the frame 10 (attached state).

[0037] In this mounted state, the clamp device is in a state where an end surface 45 of the flange portion 44 of the housing member 42 facing the clamp piston 40 abuts against an end surface 11b of the expanded diameter portion of the accommodating hole 11 facing the bottom surface of the frame 10. The mounted state is fixed by inserting a bolt into a hole drilled in the thickness direction of the flange portion 44 and screwing it into the frame 10. In this mounted state, the tip of the pressing portion 40a of the clamp piston 40 is positioned close to the clamp disc 28. Since the thickness dimension of the flange portion 44 is as described above, in this mounted state, the bottom surface of the housing member 42 (flange portion 44) of the clamp device is positioned within the accommodating hole 11 (slightly inward from the bottom surface of the frame 10).

[0038] In the above-described circular table device 1 serving as a rotary indexing device for a machine tool, according to the present invention, the frame 10 of the circular table device 1 is configured to have both a hydraulic oil supply path 32 for supplying hydraulic oil to the hydraulic clamping device H, and a compressed air supply path 34, which is a supply path separate from the hydraulic oil supply path 32, for supplying compressed air to the pneumatic clamping device P. An embodiment (example) of such a circular table device 1 according to the present invention will be described in detail below.

[0039] First, in the clamp device, a communication passage for pressing the clamp piston 40 toward the clamp disc 28 and supplying the working fluid to the pressure chamber 50 is formed in the housing member 42. Specifically, in the hydraulic clamp device H, as shown in Fig. 3, the communication passage 54 is made up of a partial flow passage 54a that opens at an end face 45a of the flange portion 44a of the housing member 42a and extends in the thickness direction of the flange portion 44a, a partial flow passage 54c that opens at the bottom surface of the insertion groove 43a in the housing member 42a to form the pressure chamber 50 and extends parallel to the partial flow passage 54a, and a partial flow passage 54b that extends in the radial direction to connect the partial flow passage 54a and the partial flow passage 54c.

[0040] On the other hand, in the pneumatic clamping device P, as shown in Fig. 4, the communication passage 56 is formed so as to open to the outer peripheral surface of the housing member 42b and extend radially to open to the outer inner surface of the insertion groove 43b of the housing member 42b. However, the communication passage 56 is formed so as to open into the insertion groove 43b at a position as close as possible to the bottom surface of the insertion groove 43b in the up-down direction of the frame 10 (depth direction of the insertion groove 43b). Note that in the pneumatic clamping device P, a plurality of communication passages 56 (for example, four) are formed at intervals in the circumferential direction of the housing member 42b.

[0041] Furthermore, the frame 10 of the circular table device 1 is provided with a hydraulic oil supply passage 32 which is formed to communicate with the communicating passage 54 (to supply hydraulic oil to the communicating passage 54) when the clamping device is a hydraulic clamping device H and when the hydraulic clamping device H is attached to the frame 10, and a compressed air supply passage 34 which is formed to communicate with the communicating passage 56 (to supply compressed air to the communicating passage 56) when the clamping device is a pneumatic clamping device P and when the pneumatic clamping device P is attached to the frame 10.

[0042] The hydraulic oil supply passage 32 includes a hydraulic oil inlet 32a to which a hydraulic oil supply device is connected, and a communication passage 32b for communicating the hydraulic oil inlet 32a with the hydraulic clamp device H. As shown in FIG. 3 , the hydraulic oil inlet 32a opens to a side surface of the frame 10 and is formed so as to extend radially toward the center of the accommodation hole 11. The hydraulic oil inlet 32a is also formed so as to extend radially to a position overlapping with the expanded diameter portion of the accommodation hole 11. The communication passage 32b extends in the vertical direction of the frame 10 and is formed so as to open to an end face 11b of the expanded diameter portion of the accommodation hole 11. The position of the hydraulic oil supply passage 32 in the circumferential direction of the accommodation hole 11 (frame 10) is such that the communication passage 32b communicates with a partial flow path 54a of a communication passage 54 in the hydraulic clamp device H when the hydraulic clamp device H is attached to the frame 10 at a predetermined angle.

[0043] The compressed air supply path 34 is made up of a compressed air inlet 34a to which a compressed air supply device is connected, an annular groove 34c for forming the annular flow path 36 with which the communicating path 56 in the pneumatic clamping device P directly communicates, and a communicating path 34b for communicating between the compressed air inlet 34a and the annular groove 34c. Of these, the annular groove 34c is formed so as to open onto the inner circumferential surface of the receiving hole 11 and extend around the entire circumference. Therefore, when the pneumatic clamping device P is attached to the frame 10, the annular groove 34c and the outer circumferential surface of the housing member 42b form the annular flow path 36.

[0044] The annular groove 34c has a groove width (vertical dimension) larger than the diameter of the communicating passage 56. Furthermore, the annular groove 34c is formed at a height in the vertical direction such that the communicating passage 56 is located within the range within which it exists when the pneumatic clamping device P is attached to the frame 10. Therefore, when the pneumatic clamping device P is attached to the frame 10, the annular flow path 36 formed by the annular groove 34c and the communicating passage 56 in the pneumatic clamping device P are directly connected to each other.

[0045] As shown in Fig. 4, the compressed air inlet 34a opens to a side surface of the frame 10 and is formed so as to face radially toward the center of the accommodation hole 11. However, as shown in Fig. 1, the compressed air inlet 34a is formed so as to open to a side surface different from the side surface on which the hydraulic oil inlet 32a opens. The compressed air inlet 34a is formed at a position such that its center coincides with the center of the annular groove 34c when viewed in the radial direction. Furthermore, the compressed air inlet 34a and the annular groove 34c (annular flow path 36) are connected by a connecting passage 34b extending in the radial direction.

[0046] In the circular table device 1 equipped with the frame 10 having the configuration described above, when the hydraulic clamp device H is used as the clamp device, the hydraulic clamp device H is attached to the frame 10 at a predetermined phase as described above. When the hydraulic clamp device H is attached, the communication passage 54 (partial flow passage 54a) of the hydraulic clamp device H communicates with the communication passage 32b of the hydraulic oil supply passage 32 in the frame 10 as described above, and therefore the hydraulic oil inlet 32a of the hydraulic oil supply passage 32 communicates with the communication passage 54. In other words, the hydraulic clamp device H communicates with the hydraulic oil supply passage 32 in the frame 10.

[0047] On the other hand, when a pneumatic clamping device P is used as the clamping device, the pneumatic clamping device P is attached to the frame 10. When the pneumatic clamping device P is attached, as described above, the communication passage 56 of the pneumatic clamping device P and the annular flow path 36 formed by the annular groove 34c of the compressed air supply path 34 in the frame 10 are in direct communication with each other, and therefore the compressed air inlet 34a of the compressed air supply path 34 and the communication passage 56 are in communication with each other. In other words, the pneumatic clamping device P and the compressed air supply path 34 in the frame 10 are in communication with each other.

[0048] As described above, according to the circular table apparatus 1 of this embodiment, the frame 10 has both the hydraulic oil supply path 32 for the hydraulic clamping device H and the compressed air supply path 34 for the pneumatic clamping device P, so the frame 10 can be used in both cases where the hydraulic clamping device H and the pneumatic clamping device P are used as the clamping device. This eliminates the need for a manufacturing factory that produces a large number (various types) of circular table apparatuses 1 to produce different frames 10 depending on the clamping device used, thereby reducing the overall manufacturing costs.

[0049] The present invention is not limited to the examples described above (the above examples), but can also be implemented in modified embodiments such as the following (1) to (5).

[0050] (1) The above embodiment is an example of the configuration of the frame 10 (hydraulic oil supply passage 32, compressed air supply passage 34) in the case where a so-called constantly unclamping type clamping device is used, in which hydraulic fluid is supplied to the pressure chamber 50 during clamping to move the clamp piston 40 forward toward the clamp disc 28, and the clamp piston 40 is moved back toward the housing member 42 to achieve the unclamped state by the compression spring 48. However, the present invention is not limited to circular table apparatuses that use such a clamping device, and can be applied to circular table apparatuses that use other types of clamping devices.

[0051] For example, Fig. 5 shows an example in which the present invention is applied to a circular table apparatus 1 employing a so-called constant clamping type clamping device, in which the clamp piston 40 is constantly biased toward the clamp disc 28 by a compression spring 49 and the clamp piston 40 is returned toward the housing member 42 by supplying hydraulic fluid to a pressure chamber 52. Note that Fig. 5 depicts a hydraulic clamping device H' in the right half and a pneumatic clamping device P' in the left half. In the drawing, the hydraulic oil supply path 32 that supplies hydraulic oil to the hydraulic clamping device H' and the compressed air supply path 34 that supplies compressed air to the pneumatic clamping device P' are depicted on the same plane in the frame 10. However, in reality, the hydraulic oil supply path 32 and the compressed air supply path 34 are formed 90° out of phase with each other around the central axis C of the accommodation hole 11, as in the previous embodiment.

[0052] In the configuration of both clamp devices, the clamp piston 40 is configured so that a compression spring 49 for biasing the clamp piston 40 is interposed between the housing member 42 and the clamp piston 40. The clamp piston 40 is also configured so that a small space exists in the axial direction between the guide portion 40b and the support member 46 (which is part of the housing in the present invention) when the tip of the pressing portion 40a is in contact with the clamp disc 28. In the clamp device, this space becomes a pressure chamber 52.

[0053] Furthermore, in the hydraulic clamp device H', the communicating passage 58 is formed so as to communicate with the pressure chamber 52 and, on the supply side, open to the end surface 45a of the flange portion 44a of the housing member 42a at a position where it communicates with the hydraulic oil supply path 32 (communicating passage 32b), as in the above embodiment. In the pneumatic clamp device P', the communicating passage 59 is formed so as to communicate with the pressure chamber 52 and, on the supply side, open to the outer peripheral surface of the housing member 42b at a position where it communicates with the compressed air supply path 34 (annular groove 34c (annular flow path 36)). Thus, by configuring the frame 10 in the same manner as in the above embodiment, the frame 10 can be used both when the hydraulic clamp device H' and the pneumatic clamp device P' are used as the clamp device.

[0054] The clamp device employed may be of the type described above, i.e., in which either the forward or backward movement of the clamp piston is driven by a compression spring, or may be of a type in which both the forward and backward movement are driven by the supply of hydraulic fluid. In this case, the hydraulic clamp device would be provided with the communicating passages 54 and 58 shown in Figures 3 and 5, and the pneumatic clamp device would be provided with the communicating passages 56 and 59 shown in Figures 4 and 5, and the frame would be provided with two hydraulic oil supply passages corresponding to the hydraulic clamp device and two compressed air supply passages corresponding to the pneumatic clamp device. However, in this case, the two hydraulic oil supply passages would be formed in different phase positions, and the two compressed air supply passages would be formed in different phase and vertical positions.

[0055] Furthermore, in the above explanation, examples have been described in which the same type of clamping device (hydraulic clamping device, pneumatic clamping device) (constant unclamping type, constant clamping type, or type (emergency type) that performs both clamping and unclamping by supplying hydraulic fluid) is used, but the present invention is also applicable to cases in which different types of clamping devices are used, hydraulic and pneumatic. When a constant unclamping type is used for one hydraulic clamping device and a constant clamping type for the other, as described above, the frame itself has the same supply paths (hydraulic oil supply paths and compressed air supply paths) as when a constant unclamping type or constant clamping type is used for both. However, when the emergency type is used for one device and a constant unclamping type or constant clamping type is used for the other, the frame has different numbers of hydraulic oil supply paths and compressed air supply paths (two for one device and one for the other).

[0056] It should be noted that the clamping device, particularly the pneumatic clamping device, is not limited to one having one pressure chamber for using compressed air to move the clamp piston back and forth as described above, but one having two pressure chambers may also be employed as the clamping device of the present invention. When such a pneumatic clamping device is employed, even if it is of a constantly unclamping type, two compressed air supply paths corresponding to the clamping device will be formed in the frame so as to communicate with each pressure chamber.

[0057] (2) Regarding the hydraulic oil supply passage and the compressed air supply passage in the frame, in the examples described above, the hydraulic oil supply passage 32 is formed so that the communicating passage 54 (58) opens to the end face 45a of the flange portion 44a of the housing member 42a as the hydraulic clamp device H (H'), and the hydraulic oil supply passage 32 is formed so that it opens to the end face 11b of the expanded diameter portion of the accommodating hole 11 (frame 10) that faces the end face 45a of the flange portion 44a. Also, regarding the compressed air supply passage 34, the pneumatic clamp device P (P') is formed so that the communicating passage 56 (59) opens to the outer peripheral surface of the housing member 42b, and the compressed air supply passage 34 is formed so that it opens to the inner peripheral surface of the accommodating hole 11 (frame 10) that faces the outer peripheral surface of the housing member 42b.

[0058] However, the rotary indexing device to which the present invention is applied is not limited to one to which a clamping device such as that described in the above embodiment is applied, and therefore the hydraulic oil supply path and the compressed air supply path are also formed in the frame according to the clamping device employed.

[0059] For example, in a case where a hydraulic clamping device is used in which the communication passage is formed to open on the outer peripheral surface of the housing member 42b, similar to the pneumatic clamping device P shown in Fig. 4, the hydraulic oil supply passage is formed to open on the inner peripheral surface of the accommodating hole 11 (frame 10) in a state facing the outer peripheral surface of the housing member 42b, similar to the compressed air supply passage 34. In addition, in a case where a pneumatic clamping device is used in which the communication passage is formed to open on the flange portion 44a of the housing member 42a, similar to the hydraulic clamping device H shown in Fig. 3, the compressed air supply passage is formed to open on the end face 11b of the expanded diameter portion of the accommodating hole 11 (frame 10) in a state facing the end face 45a of the flange portion 44a, similar to the hydraulic oil supply passage 32.

[0060] (3) Regarding the clamping device, in the above-described embodiment, the hydraulic clamping device and the pneumatic clamping device employed for the common frame are substantially the same in each component, such as the housing member and the clamp piston, and their combinations, except for the communication passages for the working fluid. However, in the rotary indexing device of the present invention, the hydraulic clamping device and the pneumatic clamping device employed for the common frame do not have to be structurally the same.

[0061] The clamping device to be employed may be any of a variety of well-known types with different housing configurations, piston guiding configurations, etc. However, even if the hydraulic clamping device and the pneumatic clamping device are configured differently, in the present invention the frame is shared by both clamping devices, and therefore the outer diameter of the portion of the frame that fits into the receiving hole (the portion that abuts against the inner peripheral surface of the receiving hole) in both clamping devices (mainly the housing) must be the same (approximately the same as the inner diameter of the receiving hole).

[0062] Furthermore, when the housings of both clamping devices have flanges, and when structurally different clamping devices are used as described above, the outer diameters of the flanges of the two clamping devices may be different. Therefore, in this case, the outer diameter of the flange of at least one clamping device will be smaller than the inner diameter of the expanded portion of the receiving hole. However, the outer diameter of the flange can be any size as long as it does not interfere with the formation of the supply path, etc.

[0063] In addition, when the outer diameter of the flange portion is smaller than the inner diameter of the expanded diameter portion of the receiving hole, a gap will exist between the frame (inner peripheral surface of the expanded diameter portion) and the flange portion (outer peripheral surface), but this is not a particular problem as long as it does not cause any problems in terms of use of the device (for example, if cutting oil can be prevented from entering the frame by the way a sealing member is provided, etc.). Also, the gap may be filled with a separate member (annular adapter).

[0064] Furthermore, when the circular table to which the present invention is applied is a so-called horizontally-mounted circular table in which the axis of the spindle is oriented horizontally, the receiving hole of the frame may not have an enlarged diameter portion, and the clamp device may be provided with its flange located outside the frame. In this case, the frame can be shared for both clamp devices without particularly considering the relationship between the size of the receiving hole and the size of the flange in the frame.

[0065] Furthermore, as described above, when the circular table apparatus to which the present invention is applied is a horizontally-mounted circular table apparatus, the thickness of the flanges of both clamping devices does not need to be the same. Furthermore, even if the circular table apparatus is configured such that the receiving hole in the frame has an enlarged portion and the flanges of both clamping devices are located within the enlarged portion, the thickness of one or both clamping devices may be such that a portion of the flange protrudes from the frame when attached to the frame.

[0066] (4) In the above-described embodiment, the circular table device 1 includes the drive mechanism 16 for rotationally driving the main shaft 12, and the drive mechanism 16 includes a worm gear mechanism including the worm wheel 24 to which the main shaft 12 is fixed and the worm shaft 26 including a worm meshing with the worm wheel 24, as a drive transmission mechanism for transmitting the rotation of the output shaft of the drive motor M, which is the drive source, to the main shaft 12. However, the drive mechanism is not limited to being configured in this manner.

[0067] For example, the drive mechanism may employ a so-called roller gear cam mechanism as a drive transmission mechanism, which includes a roller gear to which the main shaft is fixed and which has multiple rollers arranged in the circumferential direction, and a roller camshaft having a spiral cam groove with which the roller gear meshes. Alternatively, the drive transmission mechanism may employ a so-called ball drive mechanism (ball reducer) in which a worm wheel and a worm are indirectly engaged with each other via a ball as an engaging member. Alternatively, the drive mechanism may employ a DD motor (direct drive motor) as a drive source that directly drives and rotates the main shaft without using a drive transmission mechanism.

[0068] (5) In the above-described examples of the rotary indexing device for machine tools to which the present invention is applied, the rotary indexing device is a so-called single-axis circular table device having only one rotary axis (main axis) and performing rotary indexing on that rotary axis, but the present invention is also applicable to each indexing unit in a so-called two-axis circular table device (tilting circular table device) that has a rotary indexing unit whose main axis is a rotary axis for rotating and driving a circular table on which a workpiece or the like is attached, and a tilting indexing unit whose main axis is a tilting axis for supporting and tilting the rotary indexing unit. Furthermore, the present invention is not limited to application to the single-axis or two-axis circular table device described above, and can also be applied, for example, to an angular indexing unit (rotary indexing device) of a so-called milling head configured to index the angular position of a spindle supported by a support axis corresponding to the main axis around the axis of that support axis.

[0069] Furthermore, the present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0070] 1 Rotary Table Device 10 Frames 10a surface 11 accommodation hole 11a Inner surface 11b End surface 12 Spindle 14 Table 16 Drive mechanism 20 Bearing 24 Worm wheel 26 Worm shaft 28 Clamping disc 32 hydraulic oil supply passage 32a hydraulic oil inlet 32b Communication path 34 Compressed air supply path 34a Compressed air inlet 34b Communication passage 34c Annular groove 36 Annular flow passage 40 Clamp piston 40a Pushing part 40b Guide part 41 volts 42, 42a, 42b Housing members 43, 43a, 43b Insertion grooves 44, 44a, 44b Flange portion 45, 45a End face 46 Support member 46a Hole 48, 49 Compression spring 50, 52 Pressure chamber 54, 56, 58, 59 Communication passage 54a, 54b, 54c partial channels H, H' Hydraulic clamp device P, P' Pneumatic clamp device

Claims

[Claim 1] a clamping device for clamping the clamping disc in cooperation with the frame; a clamping piston pressed against the clamping disc; and a housing configured to slide and guide the clamping piston in a clamping direction and detachably provided on the frame with the clamping piston accommodated in the accommodation hole; and a rotary indexing device for a machine tool configured to supply a working fluid to a pressure chamber formed between the housing and the clamping piston in the clamping device, the rotary indexing device comprising: a frame having an accommodation hole formed therethrough, the frame rotatably supporting a spindle within the accommodation hole; a clamping disc attached to the clamping disc so as to be immovable relative to the spindle; the clamping device is a hydraulic clamping device that uses hydraulic oil as the working fluid or a pneumatic clamping device that uses compressed air as the working fluid, The frame is configured to be able to mount either the hydraulic clamp device or the pneumatic clamp device, and has both a hydraulic oil supply path for supplying the hydraulic oil to the hydraulic clamp device and a compressed air supply path that is a supply path separate from the hydraulic oil supply path and is used to supply the compressed air to the pneumatic clamp device. A rotary indexing device for a machine tool characterized by:

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