Rotating Table Device

Abstract

To suppress the deterioration of rotation control performance and rotary positioning accuracy.SOLUTION: A rotary table device is equipped with a rotary table, a casing rotatably supported, a housing fixed to the casing, a center shaft raised toward the rotary table at a position corresponding to a rotation axis, a housing that is provided separately from the center shaft at a position surrounding the center shaft, a center sleeve that is disposed between the center shaft and the housing, a rotary encoder that is disposed on the center shaft and the rotary table, a plurality of recessed portions formed on at least either one of an inner peripheral surface or an outer peripheral surface, a plurality of O-rings that is disposed at a position held between the inner peripheral surface and the outer peripheral surface, an in-housing fluid channel that is formed inside the housing and communicates with the plurality of recessed portions respectively, and a plurality of in-sleeve fluid channels that is formed inside the center sleeve, communicates with the plurality of recessed portions respectively and supplies a fluid to a channel of a fluid provided on the rotary table.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A rotary table device is known that has a distributor and distributes and supplies fluids such as air and oil to a rotary table on which a workpiece or a device for machining the workpiece is fixed (for example, Patent Document 1). The distributor has a fixed center sleeve, a center shaft that rotates relative to the center sleeve, a plurality of annular recesses provided in the axial direction on the inner circumference of the center sleeve, a first pass hole that communicates radially with the recesses on the outer diameter side, and a second pass hole that communicates radially with the recesses on the inner diameter side. The rotary table device supplies fluid from a fluid flow path provided in the center sleeve through the first pass hole to the recesses and through the second pass hole to a fluid flow path formed in the center shaft. The center shaft is connected to a table, and the fluid supplied to the fluid flow path of the center shaft is sent to the table and used to drive a device on the table, such as a chuck device. The fluid includes liquids such as oil and coolant, and gases such as air. In order to suppress leakage of fluid between the plurality of recesses at the boundary surface between the center sleeve and the center shaft, O-rings are provided on both sides of the recesses in the axial direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-161995 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the number of air or oil distributed by the distributor increases, the number of recesses increases, and the number of O-rings also increases. When the number of O-rings increases, the sliding resistance of the O-rings increases when the center shaft rotates. When the center shaft rotates, the center sleeve is twisted due to this sliding resistance. Although not described in Patent Document 1, when an encoder that detects the rotation of the rotary table is provided between the center sleeve and the center shaft at one end in the axial direction, the twisting of the center sleeve generates a rotation non-detection zone of the encoder, resulting in lost motion of the rotary table. As a result, it is expected that the rotation control performance and the rotation positioning accuracy will be deteriorated. Therefore, a configuration that suppresses the deterioration of the rotation control performance and the rotation positioning accuracy caused by the sliding resistance of the O-ring is desired. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, there is provided a rotary table device. The rotary table device includes a rotary table and a housing that supports the rotary table so as to be rotatable about a rotation axis. ,before a center shaft that is erected toward the rotary table at a position of the housing corresponding to a rotation center of the rotary table; A housing fixed to the enclosure, a housing provided at a position surrounding the center shaft and spaced from the center shaft, the housing having an inner circumferential surface that has a circular cross section over a predetermined range along the rotation axis; fixed to the rotary table, On the outside of the center shaft and on the inside of the housing , concentric with the axis of rotation Placed Cylindricala rotary encoder disposed on the center shaft and on the rotary table for detecting a rotation angle of the rotary table; a plurality of recesses formed on at least one of the inner peripheral surface and the outer peripheral surface to form a fluid flow path; a plurality of O-rings disposed at positions sandwiched between the inner peripheral surface and the outer peripheral surface to suppress leakage of fluid from the plurality of recesses; an inner-housing fluid flow path formed inside the housing and communicating with each of the plurality of recesses; and a plurality of inner-sleeve fluid flow paths formed inside the center sleeve and communicating with each of the plurality of recesses to supply fluid to a fluid flow path provided on the rotary table. A gap is formed between the inner peripheral surface of the cylindrical center sleeve and the outer peripheral surface of the center shaft, and no O-ring is in contact with the gap to cause sliding resistance. According to this type of rotary table device, even if the rotary table and center sleeve rotate relative to the housing and sliding resistance of the O-ring between the center sleeve and the housing occurs, the center shaft is not affected by the sliding resistance of the O-ring because the O-ring is not present between the center sleeve and the center shaft. As a result, a rotation non-detection zone of the rotary encoder provided on the center shaft is not generated, and no lost motion of the rotary table occurs. As a result, deterioration of rotation control performance and rotation positioning accuracy caused by the sliding resistance of the O-ring can be suppressed. (2) In the rotary table device of the above aspect, the recesses may have an annular groove shape. According to the rotary table device of this aspect, since the recesses have an annular groove shape, the fluid can be stably supplied from the housing to the center sleeve regardless of the rotational position of the center sleeve. (3) In the rotary table device of the above aspect, the recesses may be formed on the inner peripheral surface of the housing. According to the rotary table device of this aspect, since no recesses are formed in the center sleeve, the thickness of the center sleeve can be made thin. (4) In the above-described rotary table device, a rotary support may be provided between the center shaft and the center sleeve. With this rotary table device, the distance between the center shaft and the center sleeve can be kept constant, and wobbling of the center sleeve can be suppressed. (5) In the rotary table device of the above aspect, the rotary support portion may be formed of a roller bearing device or a dry bush. With this rotary table device, friction between the center shaft and the center sleeve can be reduced. (6) The present disclosure may be realized in various forms other than a rotary table device, such as a processing device, a machining center, etc. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram of a five-axis machining center equipped with a rotary table device. [Diagram 2] FIG. 2 is an explanatory diagram showing a configuration of a rotary table device. [Diagram 3] 3 is an explanatory diagram showing an enlarged view of region III in FIG. 2. [Figure 4] FIG. 11 is an explanatory diagram showing the configuration of a rotary table device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] First embodiment: 1 is an explanatory diagram of a five-axis machining center 10 equipped with a rotary table device 30. The five-axis machining center 10 is equipped with a bed 20, a rotary table device 30, a turning spindle 70 with a built-in chuck device, a column 80, and a saddle 90. The five-axis machining center 10 is a horizontal type, with the vertical direction being the y-axis direction, and the horizontal directions intersecting with the y-axis direction being called the x-axis direction and z-axis direction.

[0009] Bed 20 includes a pair of rails 21 extending along the z-axis, and a work table 25 in the -z direction of rails 21. A pair of rails 26 extending along the x-axis are disposed on work table 25. A rotating table device 30 is disposed on rails 26. Rotating table device 30 can be moved on rails 26 along the x-axis by a servo motor (not shown).

[0010] The rotary table device 30 has a rotary table 31, which can rotate around the B axis. A turning spindle 70 incorporating a chuck device is disposed on the rotary table 31. The turning spindle 70 is also called a turning main shaft. The turning spindle 70 grips the workpiece 100 and can rotate the workpiece 100 around the A axis by a motor (not shown). The force used to grip the workpiece 100 is provided by hydraulic pressure supplied via the rotary table device 30. The supply route will be described later.

[0011] A column 80 is disposed on the rail 21, and the column 80 can be moved on the rail 21 along the z-axis by a servo motor (not shown). A pair of rails 81 extending along the y-axis are disposed on the column 80. A saddle 90 is disposed on the rail 81. The saddle 90 can be moved on the rail 81 along the y-axis by a servo motor 82. A spindle 91 is provided on the saddle 90, and a tool for machining a workpiece is attached to the spindle 91. The spindle 91 is also called a main shaft. A motor (not shown) rotates the spindle 91, which rotates the tool, which then machines the workpiece 100. If a skiving tool is used as the tool, the rotation of the tool and the rotation of the workpiece 100 are linked, and the tool is moved axially relative to the workpiece 100, skiving of the tooth surface of the workpiece 100 can be performed. If a rotary table device 30 (described later) is used, the machining accuracy of the tooth surface is improved.

[0012] FIG. 2 is an explanatory diagram showing the configuration of the rotary table device 30. The rotary table device 30 includes rotating system components and stationary system components that do not rotate. The rotary table device 30 includes, as the rotary system components, a rotary table 31 (see FIG. 1; not shown in FIG. 2), a center sleeve 40, a first rotor 51, a second rotor 52, a rotor magnet 54 of the built-in motor, an inner ring 55 of the rolling bearing, a first connecting portion 56 connecting the center sleeve 40 and the second connecting portion 57, a second connecting portion 57, and an inner rotor portion 63a of the encoder. The rotary table device 30 also includes, as the stationary system components, a housing 60, a center shaft 61, an encoder mounting portion 62 connecting the center shaft 61 and the casing 63b, a casing 63b on the outer diameter side of the encoder, a housing 64, a housing support portion 65, a stator coil 66 of the built-in motor, and an outer ring 67 of the rolling bearing.

[0013] The housing 60 includes a disk portion 60b that constitutes the bottom surface of the rotary table device 30, and a cylindrical portion 60a that rises from the outer periphery of the disk portion 60b. Here, the disk portion 60b side is called "lower", and the direction in which the cylindrical portion 60a rises is called "upper". An opening 60c is formed at the center of the disk portion 60b. A cable and other signal lines (not shown) for sending the output from the casing 63b on the outer diameter side of the encoder to an external control device (not shown) pass through this opening 60c. The B axis OB, which is the center of the housing 60, passes through the center of the opening 60c. The B axis OB is the rotation axis of the rotary table 31. A center shaft 61 having a cylindrical shape with the B axis OB as the central axis is erected on the disk portion 60b. A flange-shaped fixing portion 61a is formed at the lower end of the center shaft 61, and the fixing portion 61a is fixed to the disk portion 60b of the housing 60 by a screw (not shown). In FIG. 2, the screws for fixing each member are not shown. On the opposite side of the disk portion 60b of the center shaft 61 (upper side in FIG. 2), the encoder mounting portion 62 is fixed to the center shaft 61 by a screw. The encoder mounting portion 62 is cylindrical and has a flange 62a on the opposite side of the center shaft 61. On the opposite side of the center shaft 61 of the flange 62a, a central portion 62b is recessed, and a casing 63b on the outer diameter side of the encoder is fixed to the recessed central portion 62b by a screw. The casing 63b on the outer diameter side of the encoder has a cylindrical shape and constitutes a rotary encoder 63 that detects the rotation angle of the rotary table 31 together with a rotor portion 63a that rotates together with the rotary table 31. In this embodiment, a magnetic or optical rotary encoder can be used as the rotary encoder.

[0014] The center sleeve 40, which is a rotating system member, is disposed on the outside of the center shaft 61 with a small gap therebetween. The center sleeve 40 has a cylindrical shape with the B-axis OB concentric therewith. A flange 40a is formed on the side of the center sleeve 40 opposite the housing 60. A cylindrical first rotor 51 with the B-axis OB concentric therewith is disposed on the outer periphery of the flange 40a. A cylindrical second rotor 52 with the B-axis OB concentric therewith is disposed on the outer periphery side of the first rotor 51. A rotor magnet 54 is disposed on the housing 60 side of the second rotor 52. The rotor magnet 54, together with a stator coil 66, which is a fixed system component, constitutes a built-in motor, which is a direct drive motor. An inner ring 55 of a rolling bearing is disposed on the outer periphery of the second rotor 52. The inner ring 55 of the rolling bearing, together with the outer ring 67 of the rolling bearing of the fixed system component, is supported in the vertical direction and in the radial direction to form a three-way bearing. A first connecting part 56 is fixed by a screw to the opposite side of the housing 60 of the flange 40a. The first connecting part 56 has a cylindrical part 56a concentric with the B axis OB, and a holed disk part 56b with a hole 56c formed in the center of the cylindrical part 56a on the rotary table 31 side (upper side in FIG. 2). A second connecting part 57 is fitted and fixed in the hole 56c.

[0015] The center sleeve 40 has an outer peripheral surface that is circular in cross section, and the housing 64 is disposed on the outside of the outer peripheral surface with a small gap therebetween and is fixed to the housing 60 by screws. In other words, the center sleeve 40 and the housing 64 are disposed at a distance from each other. The housing 64 has a cylindrical shape that is concentric with the B axis OB. A housing support portion 65 is disposed on the outer peripheral side of the housing 64 and is fixed to the housing 60 by screws. The housing support portion 65 supports the housing 64 from the outer peripheral side.

[0016] A stator coil 66 is disposed inside the cylindrical portion 60a of the housing 60. As described above, the stator coil 66 constitutes a direct drive motor together with the rotor magnet 54.

[0017] The housing 64 has an inner peripheral surface with a circular cross section over a predetermined range along the B axis OB, and a plurality of recesses 64a having an annular groove shape are formed on the inner peripheral surface. Between the inner peripheral surface of the housing 64 and the outer peripheral surface of the center sleeve 40, O-rings 68 are arranged above and below the recesses 64a in the direction along the B axis OB. The O-rings 68 are sandwiched between the inner peripheral surface of the housing 64 and the outer peripheral surface of the center sleeve 40, and suppress leakage of the fluid supplied to the recesses 64a. Since the O-rings 68 generate sliding resistance when the center sleeve 40 rotates, it is preferable that the number of O-rings 68 is small. Here, since the O-ring 68 between two adjacent recesses 64a can be shared, if the number of recesses 64a is n, it is sufficient to have n+1 O-rings 68. A plurality of in-housing fluid flow paths 64b are formed in the housing 64, each of which is connected to the plurality of recesses 64a. The fluid flow passage 64b is composed of a radial bus hole communicating with the recess 64a and a passage extending in the axial direction.

[0018] A plurality of in-housing fluid flow paths 60d are formed in the cylindrical portion 60a and the disk portion 60b of the housing 60, and are respectively connected to a plurality of in-housing fluid flow paths 64b of the housing 64. Fluid supply pipes 69, which are respectively connected to the plurality of in-housing fluid flow paths 60d, are connected to the cylindrical portion 60a and the disk portion 60b.

[0019] A plurality of fluid flow passages 40c are formed inside the center sleeve 40, each connected to a plurality of recesses 64a. The fluid flow passages 40c are composed of a radial pass hole communicating with the recesses 64a and a passage extending in the axial direction. The fluid flow passages 40c are connected to a fluid flow passage (not shown) of the rotary table 31 through a plurality of fluid flow passages 51a formed inside the first rotor 51. The fluid flow passage of the rotary table 31 is connected to a turning spindle 70 having a built-in chuck device through a tube (not shown). The housing 64 and the center sleeve 40 constitute a so-called distributor that distributes the fluid. The number of recesses 64a is the number of distributions of this distributor.

[0020] Fig. 3 is an explanatory diagram showing an enlarged view of region III in Fig. 2. As indicated by the arrows, the fluid is supplied from a fluid flow passage 64b formed in the housing 64, supplied to a space surrounded by the recess 64a, the center sleeve 40, and the two O-rings, and further supplied to a fluid flow passage 40c formed in the center sleeve 40. The O-ring 68 suppresses leakage of the fluid in the vertical direction.

[0021] In this embodiment, there is no O-ring between the center shaft 61, one end of which is connected to the encoder 63 in the axial direction, and the center sleeve 40, and the O-ring is disposed between the center sleeve 40 and the housing 64. Therefore, even if sliding resistance occurs in the O-ring 68 between the center sleeve 40 and the housing 64 when the center sleeve 40 rotates, the center shaft 61 does not twist because no sliding resistance acts on it. As a result, no rotation non-detection zone is generated in the encoder 63, and no lost motion of the rotary table 31 occurs.

[0022] In the above embodiment, the recess 64a is formed in the housing 64, but a recess may be formed in the center sleeve 40, or a recess may be provided in both the housing 64 and the center sleeve 40. That is, the recess may be formed in at least one of the housing 64 and the center sleeve 40. By forming the recess 64a in the housing 64, the thickness of the center sleeve 40 can be reduced.

[0023] If the recess 64a is shaped like an annular groove, the fluid can be stably supplied from the housing 64 to the center sleeve 40 regardless of the rotational position of the center sleeve 40.

[0024] Second embodiment: 4 is an explanatory diagram showing a rotary table device of the second embodiment. In the first embodiment, there is a small gap between the center sleeve 40 and the center shaft 61, but in the second embodiment, a rotation support part 42 is disposed in this gap. The distance between the center shaft 61 and the center sleeve 40 is kept constant, and wobbling of the center sleeve 40 can be suppressed. For example, a bearing device such as a roller bearing or a dry bush can be used as the rotation support part 42.

[0025] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0026] 10...5-axis machining center, 20...bed, 21...rail, 25...work table, 26...rail, 30...rotary table device, 31...rotary table, 40...center sleeve, 40a...flange, 40c...fluid flow path in sleeve, 42...rotation support portion, 51...first rotor, 51a...fluid flow path in rotor, 52...second rotor, 54...rotor magnet, 55...bearing inner ring, 56...first connecting portion, 56a...cylindrical portion, 56b...disk portion, 56c...hole, 57...second connecting portion, 60...housing, 60a...cylindrical portion, 60b...disk portion, 60c...opening, 60d...fluid flow path inside housing, 61...center shaft, 61a...fixing portion, 62...encoder mounting portion, 62a...flange, 62b...center portion, 63...encoder, 64...housing, 64a...recess, 64b...fluid flow path inside housing, 65...housing support portion, 66...stator coil, 67...bearing outer ring, 68...O-ring, 69...fluid supply pipe, 70...turning spindle device with built-in chuck device, 80...column, 81...rail, 90...saddle, 91...spindle, 100...work

Claims

1. A rotary table device, A rotating table and a housing that supports the rotary table rotatably around a rotation axis; a center shaft provided upright toward the rotary table at a position of the housing corresponding to the rotation axis; a housing fixed to the casing, the housing being provided at a position surrounding the center shaft and spaced from the center shaft, the housing having an inner circumferential surface having a circular cross section over a predetermined range along the rotation axis; a cylindrical center sleeve fixed to the rotary table, disposed outside the center shaft and inside the housing, concentric with the rotary shaft, the center sleeve having an outer peripheral surface with a circular cross section corresponding to the inner peripheral surface, the outer peripheral surface rotating concentrically with the inner peripheral surface; a rotary encoder disposed on the center shaft and the rotary table for detecting a rotation angle of the rotary table; a plurality of recesses formed in at least one of the inner circumferential surface and the outer circumferential surface to form a flow path for a fluid; a plurality of O-rings arranged at positions sandwiched between the inner circumferential surface and the outer circumferential surface to suppress leakage of fluid from the plurality of recesses; a housing internal fluid flow passage formed inside the housing and communicating with each of the plurality of recesses; a plurality of fluid flow passages formed inside the center sleeve, the plurality of fluid flow passages communicating with the respective plurality of recesses, and supplying fluid to a fluid flow passage provided in the rotary table; Equipped with A rotary table device in which a gap is formed between the inner peripheral surface of the cylindrical center sleeve and the outer peripheral surface of the center shaft, and no O-ring is present in contact with the gap to cause sliding resistance.

2. 2. The rotary table device according to claim 1, The plurality of recesses have an annular groove shape.

3. 3. The rotary table device according to claim 1, A rotary table device, wherein the recesses are formed in the inner circumferential surface of the housing.

4. A rotary table device according to any one of claims 1 to 3, A rotary table device comprising a rotary support between the center shaft and the center sleeve.

5. 5. The rotary table device according to claim 4, A rotary table apparatus, wherein the rotary support portion is constituted by a bearing device or a dry bush.

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