Rotary table device for machine tools

Abstract

To prevent a configuration malfunction from being generated in a frame while preventing foreign objects from entering the frame even if a machine tool stops and an air seal mechanism stops supply of the air into the frame in a rotary table device for machine tool equipped with the air seal mechanism.SOLUTION: A rotary table device for machine tool includes: an annular ring-shaped storage groove which is opened in a gap between a surface of a rotor opposed in the axial direction of a rotational shaft and a surface of a frame and is formed on the frame coaxially with the rotational shaft; a piston for seal which is stored in a slidable manner in the axial direction in the storage groove; an elastic member which biases the piston for seal against the rotor side; a protruding portion which is provided on the frame so as to protrude in the radial direction of the rotational shaft to the center side of the storage groove from the peripheral edge of the storage groove so as to cover a portion of the opening of the storage groove over the whole circumference; a pressure chamber which is defined by the projecting portion and the piston for seal in relation to the axial direction; and a supply device which supplies the working fluid to displace the piston for seal to the bottom side of the storage groove.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rotary table device for a machine tool, which includes a rotary shaft fixed at one end with a rotary body including a table to which a workpiece is attached, and a frame that rotatably supports the rotary shaft via a bearing in a housing hole, and the rotary shaft is rotationally driven by a driving device. In order to eject air from a gap between the surface of the rotary body facing in the axial direction of the rotary shaft and the surface of the frame, the rotary table device for a machine tool is provided with an air seal mechanism that supplies air from an air supply port formed in the frame.

Background Art

[0002] A rotary table device for a machine tool includes, for example, a rotary shaft fixed at one end with a table to which a workpiece is attached, and a frame that rotatably supports the rotary shaft via a bearing in a housing hole, and the rotary shaft is configured to be rotationally driven by a driving device having a drive motor as a drive source. Further, the rotary table device disclosed in Patent Document 1 is provided with an air purge mechanism (air seal mechanism) for supplying air to the space in the frame in order to prevent coolant liquid or the like from entering the space in the frame. Note that, regarding the air seal mechanism in the rotary table device, the pressure of the air supplied to the space in the frame is generally set to a relatively low pressure (about 0.01 to 0.03 MPa) in order to prevent problems such as the protrusion of the seal member provided in the frame.

[0003] In the rotary table device, as air is supplied into the frame from an air supply passage (supply port) formed in the frame, air is ejected from a gap between the lower surface of the table and the upper surface of the frame facing in the axial direction of the rotary shaft, preventing foreign substances such as coolant liquid from entering the frame.

[0004] In such rotary table devices, the control of the air supply device that supplies air into the frame in the air seal mechanism is generally performed by the control device of the machine tool on which the rotary table device is installed. Therefore, when the operation of the machine tool is stopped, the supply of air into the frame by the air seal mechanism is also stopped.

[0005] Furthermore, in such rotary table devices, the temperature inside the frame is high during the operation of the machine tool due to heat generated by the drive mechanism, etc., and gradually decreases when the machine tool is stopped. As the temperature decreases in this way, the temperature of the air in the space inside the frame also decreases, but normally, as air changes from a high temperature state to a low temperature state, its volume contracts. Therefore, when the machine tool is stopped and the supply of air into the frame by the air seal mechanism is stopped as described above, the temperature drops, and the contraction of the air inside the frame causes outside air to be drawn into the frame. As a result, even though the machine tool is stopped and no machining is being performed, foreign matter such as coolant liquid from the outside may enter the frame through the gap.

[0006] Although not for machine tools, a rotary table device (for semiconductor manufacturing equipment) equipped with a similar air seal mechanism is disclosed in Patent Document 2. The rotary table device in Patent Document 2 is configured to include a sealing piston that closes the gap when the supply of air to the frame by the air seal mechanism is stopped, in order to prevent foreign matter from entering the space inside the frame when the supply of air is stopped.

[0007] More specifically, in the rotary table device described in Patent Document 2, a seal case is fitted into a housing hole formed within the frame, at a position facing the rotating body. The seal case has a circular recess that opens toward the rotating body and is formed coaxially with the axis of rotation. An annular sealing piston is housed within the recess of the seal case so as to be slidable in the axial direction. Furthermore, multiple spring members (elastic members) are interposed between the sealing piston and the recess to bias the sealing piston toward the rotating body. As a result, in the rotary table device, the biasing force of the elastic members causes the sealing piston to move toward the rotating body and come into contact with it, and the space inside the sealing piston in the housing hole is closed off from the outer space that communicates with the outside.

[0008] Furthermore, the rotary table device of Patent Document 2 is equipped with a pressure chamber for moving the sealing piston toward the bottom surface side of the recess (the side away from the rotating body) against the biasing force of the elastic member. However, in that rotary table device, the pressure chamber is formed to be defined by the lower surface of the rotating body and the upper surface of the sealing piston, which are opposite each other in the axial direction. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2017-205860 [Patent Document 2] WO2006 / 004052 publication [Overview of the project] [Problems that the invention aims to solve]

[0010] Incidentally, in a rotary table device equipped with an air seal mechanism, it is necessary to eject air from the gap between the rotating body and the frame during operation of the rotary table device. Similarly, in the rotary table device disclosed in Patent Document 2, it is also necessary to eject air from the gap between the rotating body and the frame during operation of the rotary table device, so the sealing piston provided as described above needs to be separated from the rotating body during operation. This separation of the sealing piston from the rotating body is achieved by supplying compressed air (seal gas) as a working fluid to the pressure chamber.

[0011] However, as described above, if the pressure chamber is defined by the lower surface of the rotating body and the upper surface of the sealing piston, as the sealing piston moves away from the rotating body, the space within the pressure chamber becomes connected to the space inside the housing hole beyond the sealing piston (the space within the frame). As a result, the compressed air supplied to the pressure chamber is also supplied to the space within the frame.

[0012] Therefore, if the configuration of Patent Document 2, which uses such a sealing piston, is applied to a rotary table device for a machine tool equipped with an air seal mechanism as disclosed in Patent Document 1, for the purpose of preventing foreign matter from entering the frame while the machine tool is stopped, problems such as structural defects occurring within the frame will arise.

[0013] More specifically, in rotary table devices for machine tools, the air pressure supplied to the space within the frame by the air seal mechanism is set to a relatively low pressure, as described above, so as not to cause malfunctions in the sealing members provided within the frame. On the other hand, the pressure of the working fluid used to separate the sealing piston from the rotating body is set to a relatively high pressure because it is necessary to move the sealing piston against the biasing forces of the multiple elastic members described above. Furthermore, the pressure of this working fluid is much higher than the pressure of the air supplied to the space within the frame by the air seal mechanism described above.

[0014] Therefore, as described above, when compressed air, which is the working fluid supplied to the pressure chamber, is supplied to the space inside the frame as the sealing piston separates from the rotating body, the air pressure inside the frame increases, causing problems such as structural defects in the sealing member installed inside the frame, including overflow.

[0015] In view of the above-mentioned problems, the present invention aims to provide a rotary table device for a machine tool equipped with the above-described air seal mechanism that prevents foreign matter from entering the frame even when the machine tool stops and the supply of air to the frame by the air seal mechanism stops, while also preventing the above-mentioned structural problems from occurring within the frame. [Means for solving the problem]

[0016] The present invention relates to a rotary table device for a machine tool, comprising a rotating shaft fixed to one end of a rotating body including a table on which a workpiece is mounted, and a frame that rotatably supports the rotating shaft via a bearing within a housing hole, wherein the rotating shaft is rotationally driven by a drive device, and more particularly to a rotary table device for a machine tool that includes an air seal mechanism that supplies air from an air supply port formed in the frame in order to blow air out from the gap between the surface of the rotating body and the surface of the frame that are opposite each other in the axial direction of the rotating shaft.

[0017] Furthermore, the present invention provides a rotary table device comprising an annular housing groove formed in the frame that opens into the gap and is coaxial with the rotation axis, and a sealing piston that is housed within the housing groove so as to be slidable in the axial direction, The sealing piston is displaced to a position where it contacts the surface of the rotating body. An elastic member that biases the sealing piston toward the rotating body, and a part of the opening of the housing groove that covers the entire circumference Storage groove A protruding portion is provided on the frame so as to project radially from the periphery toward the center of the housing groove toward the center of the rotation axis, a pressure chamber is defined in the axial direction by the protruding portion and the sealing piston, and a working fluid with a pressure such that it displaces the sealing piston toward the bottom surface of the housing groove against the biasing force of the elastic member To the aforementioned pressure chamberIt is characterized by being equipped with a supplying device. [Effects of the Invention]

[0018] According to the present invention, in a rotary table device for a machine tool as described above, the rotary table device comprises a sealing piston that is slidably housed in a housing groove formed in a frame (housing hole) in the axial direction of the spindle, and an elastic member that biases the sealing piston toward the rotating body. Furthermore, the housing groove is formed to open in the axial direction so as to open into the gap between the surface of the rotating body and the surface of the frame. As a result, the sealing piston is displaced toward the rotating body by the biasing force of the elastic member and comes into contact with the rotating body, thereby closing the gap.

[0019] Furthermore, the rotary table device is provided with a protruding portion on the frame that extends radially from the periphery of the housing groove toward the center of the housing groove, covering a portion of the opening of the housing groove over its entire circumference. A pressure chamber for displacing the sealing piston away from the rotating body for air sealing is defined by the protruding portion and the sealing piston (which slides within the housing groove). More specifically, the pressure chamber is defined in the axial direction by the inner surface of the protruding portion facing into the housing groove (inner surface of the protrusion) and the surface of the sealing piston facing the inner surface of the protrusion (opposing surface of the protrusion). In the radial direction, the pressure chamber is defined by the inner circumferential surface of the housing groove (inner surface of the groove) and the surface of the sealing piston facing the inner surface of the groove (opposing surface of the groove). However, the inner surface of the protrusion and the inner surface of the groove are fixed surfaces.

[0020] During operation of the machine tool, working fluid is supplied to the pressure chamber to open the gap for air sealing, and the sealing piston is displaced in a direction away from the rotating body against the biasing force of the elastic body. In this case, when the sealing piston is displaced in this way, the groove-facing surface of the sealing piston slides in the axial direction, which is the direction in which the housing groove opens, at a position where the distance (distance in the opposing direction) between itself and the inner circumferential surface of the groove that it faces does not change. Therefore, even if the groove-facing surface slides in this way, the area of ​​the pressure chamber in the radial direction does not change. On the other hand, the projection-facing surface of the sealing piston is displaced in a direction away from the inner surface of the projection that it faces (in the opposing direction). However, this displacement takes place entirely within the housing groove.

[0021] Furthermore, the protruding portion is positioned to cover a part of the opening of the housing groove. In other words, the opening of the housing groove is open in the axial direction in the portion not covered by the protruding portion, and there is an open portion relative to the protruding portion. In the radial direction, the pressure chamber is closed off by the groove-facing surface of the sealing piston on the side of the housing groove where the protruding portion is located. Therefore, the sealing piston is configured such that the portion including its groove-facing surface is located in the open portion. As a result, the size of its groove-facing surface can be set in the axial direction without being restricted by the protruding portion.

[0022] Therefore, by making the size of the groove-facing surface larger than the size of the pressure chamber in the axial direction (the distance between the inner surface of the protrusion and the protrusion-facing surface) when the sealing piston is farthest from the rotating body due to the displacement, the closure in the radial direction is maintained even when the sealing piston is displaced. Moreover, according to the configuration of the present invention, it is possible to configure the sealing piston in this way. Therefore, according to the rotary table device of the present invention, while the sealing piston closes the gap during the stop of the machine tool, even if the sealing piston is displaced to open the gap during the operation of the machine tool, the operating fluid supplied for the displacement can be prevented from being supplied to the space within the frame, so that the above-described structural defect in the frame can be prevented from occurring.

Brief Description of the Drawings

[0023] [Figure 1] It is a front cross-sectional view showing a rotary table device to which the present invention is applied. [Figure 2] It is an enlarged view of the main part of FIG. 1. [Figure 3] It is a front cross-sectional view showing another embodiment of the rotary table device to which the present invention is applied.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, based on the drawings, an embodiment (example) of a rotary table device for a machine tool to which the present invention is applied will be described. The example described below is an example in which the present invention is applied to a so-called horizontally installed rotary table device 1 in which the axis of the rotating shaft is oriented in the vertical direction.

[0025] As shown in Figures 1 and 2, the rotary table device 1 comprises a frame 10 having a housing hole 17, a rotating shaft 30 rotatably supported by the frame 10 via a bearing 31 within the housing hole 17, and a rotary table 20 attached to one end of the rotating shaft 30. The rotary table device 1 also comprises a drive device 5 for rotationally driving the rotating shaft 30 and a clamping device 40 for holding the rotating shaft 30 at an indexed angular position.

[0026] Of these, the frame 10 consists of a main body portion 11, which is the main part, and a front cover 12 and a rear cover 15 that are attached to the main body portion 11. The main body portion 11 also has a through hole formed to penetrate from one end face to the other end face.

[0027] The front cover 12 is attached to the end face of the main body 11 at one end. The front cover 12 is a disc-shaped (donut-shaped) member with a through hole in the center. The front cover 12 is attached to the main body 11 in such a way that, in a plan view, the center of its through hole coincides with the center of the through hole in the main body 11.

[0028] The rear cover 15 is configured as a disc-shaped lid member (without a through hole). The rear cover 15 is attached to the main body 11 at the other end of the main body 11 so as to close the through hole of the main body 11.

[0029] In the frame 10 configured in this way, the through holes in the main body 11 and the front cover 12 are continuous in the direction of penetration, and these through holes form the aforementioned housing hole 17 inside the frame 10. The other end of the housing hole 17 is closed off by the rear cover 15.

[0030] The rotating shaft 30 is the part of the rotary table device 1 to which the disc-shaped rotary table 20 on which the workpiece is placed is attached. The rotating shaft 30 is positioned within the housing hole 17 of the frame 10 and is rotatably supported relative to the frame 10 by a bearing 31 interposed between it and the main body 11. Furthermore, in the state in which the rotating shaft 30 is positioned within the housing hole 17, one end of the rotating shaft 30 is provided to protrude slightly outside the frame 10 from the front cover 12 of the frame 10 in the axial direction.

[0031] Furthermore, the rotary table 20 is mounted to the end face of the portion on one end of the rotation shaft 30 in a orientation such that its plate thickness direction coincides with the axial direction. With the rotary table 20 mounted to the rotation shaft 30 in this manner, in the rotary table device 1, a narrow gap 64 exists between the end face 20a of the rotary table 20 on the frame 10 side and the end face 12a of the frame 10 (front cover 12) on the rotary table 20 side, which are facing each other in the axial direction.

[0032] Furthermore, in the main body portion 11 of the frame 10, the through hole is formed such that its inner diameter is enlarged in the range from approximately the center in the direction of penetration to the end face on the other end. A drive device 5 for rotationally driving the rotating shaft 30 is then arranged in the enlarged portion of the through hole. In this embodiment, the drive device 5 is mainly composed of a direct drive motor (DD motor 50) that rotationally drives the rotating shaft 30 without the use of a drive mechanism such as gears. The DD motor 50 is a so-called inner rotor type DD motor 50, in which the motor rotor 51 is fixed to the rotating shaft 30, and the motor stator 52 is fixed to the frame 10 in a manner that surrounds the motor rotor 51.

[0033] The clamping device 40 is a so-called disc-type clamping device that holds the rotating shaft 30 by pressing a clamping piston 43 against a clamping disc 41 attached to the rotating shaft 30. In the clamping device 40, a housing groove 42 is formed in the main body portion 11 of the frame 10, opening to the end face on the front cover 12 side, so as to be concentric with the rotating shaft 30 around the rotating shaft 30. The ring-shaped clamping piston 43 is housed in this housing groove 42. Furthermore, the clamping piston 43 can be displaced in the axial direction while housed in the housing groove 42.

[0034] Furthermore, in the frame 10, a gap exists between the main body 11 and the front cover 12 inside the receiving groove 42 of the main body 11 in the radial direction of the rotating shaft 30. The clamp disc 41 is mounted so as not to rotate relative to the rotating shaft 30 at the position of the gap in the axial direction. In addition, the clamp disc 41 is sized such that its outer edge is located within the receiving groove 42 in the radial direction.

[0035] Furthermore, a compression spring 45 is interposed between the clamp piston 43 and the front cover 12 at a position outside the clamp disc 41 in the radial direction. As a result, the clamp piston 43 is constantly biased toward the bottom surface of the housing groove 42 (away from the clamp disc 41). Then, when working fluid is supplied to the space between the clamp piston 43 and the bottom surface of the housing groove 42, the pressure of the working fluid displaces the clamp piston 43 toward the front cover 12, and the clamp disc 41 is clamped between the clamp piston 43 and the front cover 12. As a result, the rotating shaft 30 becomes unable to rotate.

[0036] Furthermore, the rotary table device 1 described above is equipped with an air seal mechanism 60 to prevent foreign matter from entering the inside of the frame 10. The air seal mechanism 60 is equipped with a supply channel 65 formed in the main body 11 of the frame 10 to supply air for sealing to the space inside the frame 10.

[0037] The supply channel 65 consists of an outer portion 65a that opens to the outer surface of the main body 11 and extends in the radial direction, and an inner portion 65b that opens to the end face of one end of the main body 11 within the frame 10 and extends in the axial direction. As described above, the rotating shaft 30 is supported by a bearing 31 interposed between it and the main body 11. In other words, the bearing 31 is fitted between the main body 11 and the rotating shaft 30 within a through hole in the main body 11. Furthermore, the inner portion 65b of the supply channel 65 is formed to open to the end face of the main body 11 located on the one end side of the bearing 31, and further inside the radial receiving groove 42.

[0038] As a result, the supply channel 65 communicates with the space 63 on the rotary table 20 side of the frame 10, rather than the bearing 31 (the space communicating with the aforementioned gap 64). The opening 65d of the inner portion 65b of the frame 10 relative to the main body 11 becomes the air supply port.

[0039] Furthermore, in the supply channel 65, the outer portion 65a is formed to connect the opening to the outer surface of the main body 11 with the inner portion 65b, as described above. The supply channel 65 is then connected at the opening to the outer surface of the main body 11 to an externally provided air (compressed air) supply device, which will be described later.

[0040] When air is supplied to the supply channel 65, it is supplied through the supply channel 65 to the space 63 inside the frame 10 from the air supply port 65d. Furthermore, as air is supplied to the space 63 in this way, and since the space 63 is in communication with the aforementioned gap 64, air is ejected from the gap 64 between the end face 20a of the rotary table 20 and the end face 12a of the front cover 12. This creates an air seal that prevents foreign matter from entering the inside of the frame 10.

[0041] Furthermore, the pressure of the air supplied for the air seal is set to a relatively low pressure to prevent problems such as the seal member protruding from the frame. Specifically, the air pressure is adjusted to approximately 0.01 to 0.03 MPa. Incidentally, the clamp disc 41 is located within the aforementioned space 63. Therefore, the rotary table device 1 is configured such that air is supplied to the gap 64 even when the clamp disc 41 is clamped between the clamp piston 43 and the front cover 12 (for example, by forming multiple ventilation holes that penetrate the clamp disc 41 in the direction of its plate thickness).

[0042] In the rotary table device 1 for machine tools described above, according to the present invention, the rotary table device 1 is configured to include an annular housing groove formed in the frame 10 that opens into the gap 64 and is coaxial with the rotating shaft 30, a sealing piston slidably housed in the housing groove, and an elastic member that biases the sealing piston toward the rotary table 20. Furthermore, the rotary table device 1 is provided with a protruding portion on the frame 10 that protrudes radially from the periphery of the housing groove toward the center of the housing groove so as to cover a part of the opening of the housing groove over its entire circumference, and the protruding portion and the sealing piston define a pressure chamber for displacing the sealing piston toward the side that separates it from the rotary table 20 for air sealing. One embodiment (example) of such a rotary table device 1 according to the present invention will be described in detail below.

[0043] In the rotary table device 1, the front cover 12 of the frame 10 has an annular groove (storage groove) 71 that opens on the end face 12a on the rotary table 20 side and is concentric with the rotation axis 30 around the rotation axis 30. However, the storage groove 71 is formed so that it is located within the range of the rotary table 20 when viewed in plan of the rotary table device 1. As a result, the storage groove 71 is a groove that opens in the axial direction relative to the gap 64.

[0044] The front cover 12 is a disc-shaped (donut-shaped) member as described above, but it is formed such that the thickness of the outer portion (outer part) relative to the housing groove 71 in the radial direction is smaller than the thickness of the inner portion (inner part) relative to the housing groove 71. Furthermore, in the front cover 12, the thickness of the inner portion is such that, when the front cover 12 is attached to the main body 11, the gap 64 between the inner portion and the rotary table 20 (the gap 64 between the end face 12a of the inner portion and the end face 20a of the rotary table 20, which are facing each other in the axial direction) is narrow enough to allow air for air sealing to be ejected to the outside of the frame 10.

[0045] Furthermore, the sealing piston 72 is provided in such a manner that it is housed in the housing groove 71. The sealing piston 72 is formed to form an annular shape in plan view in order to be housed in the housing groove 71, and its inner diameter is approximately the same as the diameter of the inner circumferential surface inside the housing groove 71, and its outer diameter is approximately the same as the diameter of the inner circumferential surface outside the housing groove 71. Therefore, the sealing piston 72 is housed in the housing groove 71 in a state where its inner and outer circumferential surfaces are in contact (sliding contact) with the corresponding inner circumferential surfaces of the housing groove 71.

[0046] Furthermore, the sealing piston 72 is a cylindrical member that forms an annular shape in plan view as described above, but the inner portion and the outer portion are formed to have different dimensions in the axial direction from the approximately midpoint in the radial direction. Specifically, the sealing piston 72 consists of a main body portion 72a, which is the inner main body portion, and a flange-shaped flange portion 72b that is formed to protrude outward from the main body portion 72a at one end of the main body portion 72a in the axial direction.

[0047] Furthermore, in the sealing piston 72, the dimensions of the main body 72a in the axial direction (the axial direction when housed in the housing groove 71) are approximately the same as the distance between the end face 12a of the inner portion of the front cover 12 and the bottom surface of the housing groove 71 in the axial direction. Therefore, when housed in the housing groove 71, the sealing piston 72 can be displaced (slid) in the axial direction by the size of the gap 64 in the axial direction. Also, the dimensions of the flange portion 72b in the axial direction are smaller than the distance between the end face 12b of the outer portion of the front cover 12 and the bottom surface of the housing groove 71 minus the size of the gap 64. The sealing piston 72 is provided with one end (the flange portion 72b side) facing the bottom surface of the housing groove 71 in the axial direction.

[0048] Furthermore, multiple compression springs 73, which are elastic members, are interposed between the sealing piston 72 and the bottom surface of the housing groove 71 at intervals in the circumferential direction of the housing groove 71. As a result, the sealing piston 72 is constantly biased toward the rotary table 20 in the axial direction.

[0049] Furthermore, a protruding member 14 is attached to the front cover 12 of the frame 10 to form a pressure chamber in combination with the sealing piston 72, which is supplied with working fluid that displaces the sealing piston 72 against the biasing force of the compression spring 73. More specifically, the protruding member 14 is a disc-shaped (donut-shaped) member with a through hole in the center. The inner diameter of the protruding member 14 is approximately the same as the outer diameter of the main body 72a of the sealing piston 72, and the outer diameter is approximately the same as the outer diameter of the front cover 12. Furthermore, the thickness dimension of the protruding member 14 is such that, when the protruding member 14 is attached to the outer portion of the front cover 12, the position of the end face 14a on the rotary table 20 side in the axial direction is approximately the same as the position of the end face 12a on the rotary table 20 side of the inner portion of the front cover 12.

[0050] Furthermore, the protruding member 14 is attached to the end face 12b on the rotary table 20 side of the outer portion of the front cover 12, with the center of its through hole aligned with the center of the through hole in the front cover 12 in a plan view. When the protruding member 14 is attached to the front cover 12 in this manner, the inner circumferential portion of the protruding member 14 protrudes radially from the outer inner circumferential surface of the housing groove 71 (the outer peripheral edge of the housing groove 71) toward the center of the housing groove 71. The radially protruding inner circumferential portion of the protruding member 14 becomes a protruding portion 14b provided on the frame 10, which protrudes radially from the periphery of the housing groove 71 toward the center of the housing groove 71, so as to cover a part of the opening of the housing groove 71 over its entire circumference.

[0051] When the protruding member 14 is attached to the front cover 12 in this manner, the inner circumferential surface 14d of the through hole in the protruding member 14 comes into contact with the outer circumferential surface (groove-facing surface) 72d of the main body 72a of the sealing piston 72, which is housed in the housing groove 71 as described above. In other words, in this state, the inner circumferential surface 14d of the through hole in the protruding member 14 and the groove-facing surface 72d of the sealing piston 72 are in slidable contact with each other.

[0052] Furthermore, the sealing piston 72 is in slidable contact with the inner circumferential surface on the outer diameter side of the housing groove 71 at the outer circumferential surface of its flange portion 72b. In addition, in this state, the end face of the protruding portion 14b of the protruding member 14 on the housing groove 71 side and the end face of the flange portion 72b on the rotary table 20 side are facing each other in the axial direction. As a result, in the rotary table device 1, a closed space 75 is formed defined by the protruding portion 14b of the protruding member 14, the sealing piston 72b, and the housing groove 71.

[0053] Furthermore, the protruding member 14 has a supply channel 76 formed therein for supplying working fluid to the space 75. The supply channel 76 consists of a supply portion that opens into the space 75 and extends in the axial direction, and an introduction portion that communicates with the supply portion, extends radially, and opens to the outer surface of the protruding member 14. The supply channel 76 is connected to a working fluid supply device 77 at the opening of its introduction portion.

[0054] Then, through the supply channel 76, the supply device 77 supplies working fluid to the space 75, and the pressure of this working fluid displaces the sealing piston 72 toward the side away from the rotary table 20 (towards the bottom surface of the housing groove 71). Therefore, the space 75 becomes a pressure chamber to which working fluid is supplied that displaces the sealing piston 72 against the biasing force of the compression spring 73.

[0055] Furthermore, in this embodiment, the working fluid supplied to the pressure chamber 75 is compressed air, and the supply device 77 is responsible for supplying this compressed air. Although not shown in the figures, the supply device 77 also serves as a supply device for supplying air (compressed air) to the aforementioned air seal mechanism 60.

[0056] However, as mentioned above, the pressure of the air supplied for the air seal is relatively low, around 0.01 to 0.03 MPa. On the other hand, the pressure of the compressed air supplied to the pressure chamber 75 needs to be high enough to displace the sealing piston 72 against the biasing force of the compression spring 73, and is higher than the pressure of the air supplied to the air seal mechanism 60, for example, around 0.4 MPa. Therefore, a pressure regulator is provided in the supply pipeline connecting the supply device 77 and the supply path 65 (air seal mechanism 60) to adjust the pressure of the compressed air. The supply device 77 supplies compressed air at the pressure supplied to the pressure chamber 75, and on the air seal mechanism 60 side, the pressure regulator adjusts the pressure of the air supplied to the supply path 65 to the low pressure mentioned above.

[0057] Furthermore, in the rotary table device 1 described above, during operation of the machine tool equipped with the rotary table device 1, compressed air is supplied by the supply device 77. This air is supplied to the supply passage 65, and as a result, the air is supplied from the air supply port 65d to the internal space 63 of the frame 10. In addition, compressed air from the supply device 77 is also supplied to the pressure chamber 75 via the supply passage 76, causing the sealing piston 72 to be displaced away from the rotary table 20. As a result, the gap 64 of the rotary table device 1 is open, and as air is supplied to the internal space 63 of the frame 10 as described above, air is ejected to the outside from the gap 64 that communicates with the space 63. In other words, the rotary table device 1 is in a state where the air seal is functioning.

[0058] On the other hand, when the machine tool stops, the supply of compressed air by the supply device 77 stops, so no air is supplied to the supply passage 65, and the air seal in the rotary table device 1 becomes non-functional. However, when the supply of compressed air from the supply device 77 stops, compressed air is also no longer supplied to the supply passage 76 (pressure chamber 75), so the sealing piston 72 is displaced toward the rotary table 20 by the biasing force of the spring member 73 and comes into contact with the end face 20a of the rotary table 20 on the frame 10 side. As a result, the gap 64 between the end face 12a of the frame 10 and the end face 20a of the rotary table 20 is closed, so even if the air seal is not functioning as described above, the intrusion of foreign matter into the frame 10 is prevented.

[0059] Furthermore, in the rotary table device 1, the pressure chamber 75 formed within the housing groove 71 that houses the sealing piston 72 is defined on the opening side of the housing groove 71 by a protruding portion 14b, and the protruding portion 14b (protruding member 14) is provided such that the groove-facing surface 72d of the sealing piston 72 slides against the inner circumferential surface 14d of the protruding portion 14b (protruding member 14). As a result, the pressure chamber 75 maintains its closed state over the range of displacement of the sealing piston 72. Therefore, even if compressed air is supplied to the pressure chamber 75 to open the gap 64 during operation of the machine tool as described above, the compressed air is not supplied to the space 63 inside the frame 10 that communicates with the gap 64, thus preventing the air pressure in the space inside the frame from increasing and causing problems such as the sealing member provided inside the frame 10 protruding.

[0060] The above describes one embodiment of the rotary table device for machine tools according to the present invention. However, the rotary table device for machine tools according to the present invention is not limited to the above embodiment, and can also be implemented in the following modified examples.

[0061] (Pressure chamber protrusion) (1) Regarding the pressure chamber, in the rotary table device 1 of the above embodiment, the pressure chamber 75 for displacing the sealing piston 72 toward the side away from the rotary table 20 is provided so as to be located outside the main body 72a of the sealing piston 72 with respect to the radial direction. However, in the present invention, the pressure chamber may be provided so as to be located inside the main body of the sealing piston with respect to the radial direction. In that case, the protruding portion will be provided so as to protrude radially from the inner peripheral edge of the housing groove toward the center of the housing groove.

[0062] Specifically, an example like the one shown in Figure 3 can be considered. In this example, in the rotary table device 100, the front cover 112 is configured such that the distance between the portion inside the housing groove 171 (end face 112a) and the rotary table 120 (end face 120a) is larger than that in the above embodiment. Furthermore, the sealing piston 172 housed in the housing groove 171 is configured to have an inner flange portion 172c that protrudes inward from its main body portion 172a, in addition to the flange portion 172b that protrudes outward as in the above embodiment.

[0063] Furthermore, a protruding member 114, whose inner diameter is the same as the inner diameter of the front cover 112, is attached to the end face 112a of the front cover 112. However, the thickness dimension of the protruding member 114 is such that, when attached to the end face 112a, the gap 164 between the protruding member 114 and the rotary table 120 is approximately the same size as the gap 64 in the above embodiment. In addition, the outer diameter of the protruding member 114 is approximately the same as the inner diameter of the main body 172a of the sealing piston 172.

[0064] As a result, when the protruding member 114 is attached to the end face 112a of the front cover 112, the outer peripheral portion of the protruding member 114 protrudes radially from the inner peripheral edge of the housing groove 171, and the outer peripheral surface 114d of the protruding member 114 is in slidable contact with the inner peripheral surface 172d of the main body 172a of the sealing piston. The portion of the protruding member 114 that protrudes radially from the inner peripheral edge of the housing groove 171 becomes the protruding portion 114b.

[0065] With this configuration, a closed space 175 is formed inside the main body 172a of the sealing piston 172 in the radial direction, defined by the protruding portion 114b, the sealing piston 172, and the housing groove 171. Then, by forming supply passages 176 and 179 in the frame 110 (protruding member 114 and front cover 114) for supplying compressed air to the space 175, the space 175 becomes a pressure chamber to which compressed air is supplied that displaces the sealing piston 172 toward the side away from the rotary table 120.

[0066] (2) Regarding the configuration for closing the gap between the surface of the rotating body that communicates with the outside and the surface of the frame in order to eject air for air sealing, in the above embodiment, the gap is closed by bringing the main body of the sealing piston into contact with the end face on the frame side of the rotary table. However, the configuration for closing the gap is not limited to such a configuration, and may be, for example, the configuration shown in Figure 3.

[0067] Specifically, the example shown in Figure 3 is an example in which a rotary table device is configured such that a cylindrical cover 121 is attached to the end face 120a of the rotary table 120 on the frame 110 side, protruding toward the frame 110. The inner diameter of the cover 121 is slightly larger than the outer diameter of the main body 172a of the sealing piston 172, and the dimensions of the cover 121 in the axial direction are such that the gap between it and the front cover 112 is about the same size as the gap 64 in the above embodiment. As a result, in this rotary table device, the gap between the cover 121 and the front cover 112 becomes a gap (a gap that communicates with the outside) through which air for air sealing is ejected.

[0068] Furthermore, the rotary table device is configured such that as the sealing piston 172 is displaced toward the rotary table 120, the flange portion 172b of the sealing piston 172 comes into contact with the end face 121a of the cover 121 toward the frame 110, thereby closing the gap.

[0069] (3) In the above embodiment, a compression spring 73 is used as the elastic member that biases the sealing piston toward the rotating body. However, in the present invention, the elastic member is not limited to a compression spring, but may be a disc spring or a corrugated washer, for example. In the case of a disc spring or a corrugated washer, the elastic member may be provided as a single member extending in the circumferential direction. Furthermore, the elastic member is not limited to being made of a metal material, but may be made of a rubber material such as a rubber bush or rubber washer, for example.

[0070] (4) In the above embodiment, the rotary table device 1 is configured such that the supply device 77, which supplies working fluid to a pressure chamber that displaces the sealing piston away from the rotating body, also supplies air for air sealing to the air seal mechanism 60. However, in the present invention, the rotary table device may be configured such that the supply device supplies compressed air only to the pressure chamber. In that case, the air seal mechanism in the rotary table device is configured to receive air from a device for supplying air for air sealing, which is provided separately from the supply device.

[0071] Furthermore, in the above embodiment, the working fluid supplied by the supply device to the pressure chamber is compressed air. However, in the case of a rotary table device in which air is supplied to the air seal mechanism by a device other than the supply device described above, the working fluid may be hydraulic oil. In other words, the supply device may be configured to supply hydraulic oil.

[0072] (5) In the above embodiment, the rotary table device for a machine tool that is the premise of the present invention is a so-called horizontal rotary table device in which the axis of the rotation shaft 30 is oriented vertically. However, the rotary table device to which the present invention is applied is not limited to such a horizontal rotary table device, but may also be a so-called vertical rotary table device in which the axis of the rotation shaft is oriented horizontally.

[0073] Furthermore, in the above embodiment, the drive device 5 in the rotary table device 1 is mainly composed of a direct drive motor (DD motor) 50 that rotates the rotating shaft 30 without going through a drive transmission mechanism such as gears. However, in the rotary table device that is the premise of the present invention, the drive device may be configured such that the drive motor rotates the rotating shaft via a drive transmission mechanism.

[0074] It should be noted that the present invention is not limited to any of the embodiments described above, and can be modified as appropriate without departing from its spirit. [Explanation of Symbols]

[0075] 1. Rotary Table Device 5. Drive unit 10 frames 11 Main body 12 Front Cover 12a End face 12b End face 14. Protruding member 14a End face 14b Projecting part 14d Inner surface 15 Rear cover 17 containment holes 20 Rotating Tables 20a end face 30 Rotation axis 31 Bearings 40 Clamping device 41 Clamp Disc 42 Storage grooves 43 Clamp Piston 45 Compression spring 50 DD motor 51 Motor Rotor 52 Motor Stator 60 Air seal mechanism 63 Space 64 gaps 65 Supply channel 65a outer part 65b Inner part 65d Air supply port 71 Retaining groove 72 Piston for seals 72a Main body part 72b Flange section 72d Groove facing surface 73 Compression spring 75 Pressure Chamber 76 Supply channel 77 Feeding device 100 Rotary Table Device 110 frames 112 Front Cover 112a End face 114 Protruding member 114b Projecting part 114d Inner surface 120-degree rotating table 120a end face 121 Hippo 121a End face 164 gap 171 Retaining groove 172 Piston for seals 172a Main body 172b Flange section 172c Inner collar 172d Inner surface 175 Pressure Chamber 176 Supply channel 179 Supply channel

Claims

[Claim 1] A rotary table device for a machine tool comprising a rotating shaft fixed to one end of a rotating body including a table on which a workpiece is mounted, and a frame that rotatably supports the rotating shaft via bearings within a housing hole, wherein the rotating shaft is rotationally driven by a drive device, and further comprising an air seal mechanism that supplies air from an air supply port formed in the frame in order to eject air from the gap between the surface of the rotating body and the surface of the frame that are opposite each other in the axial direction of the rotating shaft, The system comprises: an annular housing groove formed in the frame coaxially with the rotation axis and opening into the gap; a sealing piston slidably housed in the housing groove in the axial direction; an elastic member that biases the sealing piston toward the rotation body so that it is displaced to a position in contact with the surface of the rotation body; a protruding portion provided on the frame so as to project radially from the periphery of the housing groove toward the center of the housing groove, covering a portion of the opening of the housing groove over its entire circumference; a pressure chamber defined by the protruding portion and the sealing piston in the axial direction; and a supply device that supplies working fluid to the pressure chamber at a pressure sufficient to displace the sealing piston toward the bottom surface of the housing groove against the biasing force of the elastic member. A rotary table device for machine tools, characterized by the following features.

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