JP2023070361A - rotary table device - Google Patents

Abstract

To provide a rotary table device with a small diameter and high positioning accuracy.SOLUTION: A rotary table device includes: a housing having a cylindrical inner peripheral wall; a shaft which penetrates the housing and extends in an axial direction common to the axial direction of the inner peripheral wall; a first bearing mechanism which supports a first end side of the shaft so as to be able to move directly with respect to the housing; a motor mechanism which reciprocates the shaft in an axial direction of the shaft; and a rotary body connected to the shaft through a ball screw mechanism provided on a second end side which is an end on an opposite side of the first end side of the shaft. The rotary body is rotatably fixed to the housing via a second bearing mechanism and includes a ball screw nut and a table, which are mutually fixed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a rotary table device.

2. Description of the Related Art As a rotary table device, a known rotary table device includes a bed as a fixed portion, a rotary table, and bearings arranged therebetween, and is rotationally driven by a linear motor. For example, in the rotary table device disclosed in Patent Document 1, a plurality of magnets are arranged on the lower surface of the table along the circumferential direction of the table, and a plurality of coils are arranged on the upper surface of the bed so as to face the magnets. are arranged. The rotary table device of Patent Literature 1 is a direct drive device that rotates the table by thrust obtained from the magnetic flux of the magnet and the current flowing through the coil.

On the other hand, a linear actuator is known that combines a ball screw and a motor. The linear actuator of Patent Document 2 includes a shaft, a motor section, a ball screw nut, and a ball spline nut. The motor section includes a stator including a coil fixed to the motor exterior, and a rotor provided on the outer peripheral portion of a rotor holding shaft that is supported by the motor exterior via a bearing. The rotor holding shaft is a ball screw nut, a rotor consisting of a magnet and an iron core is formed on the outer circumference of the ball screw nut, and a ball screw groove is formed on the inner circumference of the ball screw nut. The shaft is supported via balls. The ball spline nut is non-rotatably fixed to the exterior of the motor, and has ball rolling grooves formed on its inner circumference to support the shaft via balls.

Japanese Patent No. 4608238 JP-A-4-236158

A rotary table device with a smaller diameter and higher positioning accuracy is desired. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rotary table device having a small diameter and high positioning accuracy.

A rotary table apparatus according to the present disclosure includes:
a housing having a cylindrical inner peripheral wall;
a shaft passing through the housing and extending in an axial direction common to the axial direction of the inner peripheral wall;
a first bearing mechanism that supports the first end side of the shaft so as to be directly movable with respect to the housing;
a motor mechanism that reciprocates the shaft in the axial direction of the shaft;
a rotating body connected to the shaft via a ball screw mechanism provided on a second end side opposite to the first end side of the shaft;
with
The rotating body is rotatably supported with respect to the housing via a second bearing mechanism, and includes a ball screw nut and a table fixed to each other.

According to the above configuration, a rotary table device having a small diameter and high positioning accuracy is provided.

FIG. 1 is a perspective view of a rotary table device 1 according to Embodiment 1. FIG. FIG. 2 is a sectional view showing the II-II section in FIG. 1 of the rotary table device 1. As shown in FIG. FIG. 3 is a cross-sectional view showing a partial configuration added to the cross-sectional view of FIG. FIG. 4 is a sectional perspective view showing the II-II section in FIG. 1 of the rotary table device 1. As shown in FIG. FIG. 5 is a cross-sectional view of rotary table device 101 according to the second embodiment. FIG. 6 is a cross-sectional view of a rotary table device 201 according to Embodiment 3. FIG. FIG. 7 is a cross-sectional view of a rotary table device 301 according to Embodiment 4. FIG.

[Overview of embodiment]
First, the embodiments of the present disclosure are listed and described.

A rotary table device according to the present disclosure includes a housing having a cylindrical inner peripheral wall, a shaft penetrating through the housing and extending in an axial direction common to the axial direction of the inner peripheral wall, and a second shaft of the shaft. a first bearing mechanism that supports one end side so as to be able to move directly with respect to the housing; a motor mechanism that reciprocates the shaft in the axial direction of the shaft; a rotating body connected to the shaft via a ball screw mechanism provided on the second end side, which is the end portion. The rotating body is rotatably supported with respect to the housing via a second bearing mechanism. The rotating body includes a ball screw nut and a table fixed to each other.

Conventionally, as a rotary table device, there has been known one that has a magnet row on the lower surface of the rotary table and a coil row on the upper surface of the bed facing the magnet row (for example, Patent Document 1). The rotary table device of Patent Document 1 is capable of precise positioning. On the other hand, since the magnet row that constitutes the motor is attached to the table, the smaller the diameter of the table, the smaller the magnet row, and as a result, the output of the motor is reduced. Therefore, there is a limit to reducing the diameter of the rotary table device.

On the other hand, a shaft motor is known in which a mover reciprocates on a shaft. A shaft motor is composed of a shaft including a plurality of magnets arranged in an axial direction with magnetic poles alternated, and a mover including a cylindrical coil surrounding the shaft. In a shaft motor, a thrust force is generated by applying current to a coil, and a mover moves linearly on the shaft. Conventionally, it has not been assumed that the linear motion of a shaft motor is used to rotate a table in a rotary table device.

Also known is a linear actuator in which a ball screw and a ball spline are combined and a motor is incorporated inside the ball screw nut (for example, Patent Document 2). The linear actuator of Patent Document 2 converts rotary motion of a ball screw nut into linear motion of a shaft. In the linear actuator of Patent Document 2, it is also possible to rotate or spirally move the shaft by incorporating a motor inside the ball spline nut. However, the linear actuator of Patent Document 2 cannot be applied to rotating a table held at a fixed position.

A rotary table device according to the present disclosure reciprocates a shaft in an axial direction by applying a shaft motor. A ball screw mechanism is provided at one end of the shaft. A ball screw nut in this ball screw mechanism is rotatably attached to the housing of the shaft motor via a bearing. Therefore, the ball screw nut is axially immovable and is only allowed to rotate. With these configurations, the linear motion of the shaft is converted into rotary motion of the ball screw nut, and the table fixed to the ball screw nut rotates. Since the rotary table device of the present disclosure does not have a motor component attached to the table, it is easy to reduce the diameter of the table. In addition, the conventional rotary table device does not require a rectangular base, and the size of the rotary table device in the plane direction can be further reduced. In addition, since the linear motion of the shaft is converted into the rotational motion of the table by the ball screw mechanism, the rotation can be reliably controlled. Therefore, the positioning accuracy is high. Furthermore, the rotational speed can be controlled by controlling the output of the motor. In addition, since the lead of the ball screw and the rotation angle of the table are correlated, a rotary table device having a desired rotation angle can be obtained by using a general-purpose and established method of setting and forming the lead of the ball screw.

In the rotary table device, the motor mechanism may include a coil fixed to the inner peripheral wall of the housing, and a magnetic field fixed to a position facing the coil on the outer peripheral surface of the shaft. good. By providing a linear motor as the motor mechanism, the amount of movement of the shaft, that is, the amount of rotation of the rotary table can be controlled more reliably and easily. Therefore, a rotary table device with excellent positioning accuracy can be obtained.

In the rotary table device, the first bearing mechanism is a ball spline mechanism, a ball spline nut is fixed to the housing, and a spline groove is formed on the outer peripheral surface of the shaft on the first end side. may By supporting the end (first end) of the shaft on the opposite side of the rotary table (second end) with a ball spline bearing, the allowable range of load can be increased.

In the rotary table device, the second bearing mechanism is a cross roller bearing, the bearing outer ring of the cross roller bearing is fixed to the housing, and the bearing outer ring, the ball screw nut, and the table are fixed. The inner ring of the bearing may be connected via a roller. In this rotary table device, the cross roller bearing allows loads from all directions. For this reason, it is suitable for a wider range of applications, such as being applied to the hand of a manipulator, in addition to being used for placing and rotating an object.

In the rotary table device, the magnetic field may include a magnet row in which a plurality of ring-shaped permanent magnets inserted into the shaft are aligned in the axial direction. The shaft is provided with a flange portion contacting the magnetic field at one end of the portion where the magnetic field is arranged, and the magnetic field is clamped and fixed by the flange portion and a nut fitted on the shaft. may have been With such a configuration, it is possible to reduce the number of parts constituting the rotary table device, facilitate assembly, prevent eccentricity and looseness of the shaft, and realize a highly accurate rotary table device.

The rotary table device may further include an encoder, and the encoder may include a scale attached to the outer peripheral surface of the rotating body, and an encoder head attached to the housing and facing the scale. By directly detecting the rotation of the rotating body, more accurate rotation control can be achieved.

[Specific example of embodiment]
Next, an example of specific embodiments of the rotary table device of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is an external perspective view showing the structure of a rotary table device 1, which is a rotary table device according to an embodiment of the present disclosure. FIG. 2 is a sectional view showing the II-II section in FIG. 1 of the rotary table device 1. As shown in FIG. FIG. 3 is a diagram showing the cross-sectional view of FIG. 2 with a part of the configuration added. FIG. 4 is a sectional perspective view showing the II-II section in FIG. 1 of the rotary table device 1. As shown in FIG. 1 to 4 are schematic diagrams, some of the parts constituting the rotary table device are omitted, and the detailed configuration of each part is also omitted.

Referring to FIG. 1, rotary table device 1 has an overall cylindrical appearance. The rotary table device 1 includes an outer cylinder 11 as a housing, a shaft 21 passing through the outer cylinder 11, and a table 31 as a rotary table. In the rotary table device 1, the side where the shaft 21 protrudes is called the first end side, and the side where the table 31 is provided is called the second end side.

The outer cylinder 11 has a cylindrical outer peripheral surface extending in the axial direction. A housing 12 is fixed to the first end side of the outer cylinder 11 . The housing 12 also constitutes a housing in the rotary table device 1 . The outer diameter of the housing 12 is the same as that of the outer cylinder 11 . A bearing outer ring 13 is fixed to the second end side of the outer cylinder 11 . The outer diameter of the bearing outer ring 13 is the same as that of the outer cylinder 11 . However, the external shapes of the outer cylinder 11, housing 12, and bearing outer ring 13 shown in FIG. 1 are merely examples, and the present invention is not limited to these. For example, the outer cylinder 11, the housing 12, and the bearing outer ring 13 may have different outer diameters. Moreover, the shape of the outer surface of the outer cylinder 11 and the housing 12 is not limited to a cylindrical shape, and may be a rectangular cylindrical shape. Further, a housing section for housing sensors and various cords, a mounting section for other members, and the like may be provided.

Outer cylinder 11, housing 12 and bearing outer ring 13 are fixed to each other. The outer cylinder 11 , the housing 12 and the bearing outer ring 13 constitute the fixed portion 10 in the rotary table device 1 . On the other hand, the shaft 21 is axially reciprocated by a motor mechanism 40 (FIG. 2) provided inside the outer cylinder 11 . The shaft 21 constitutes the direct acting portion 20 in the rotary table device 1 . The table 31 rotates in conjunction with the reciprocating motion of the shaft 21 . The table 31 constitutes the rotating section 30 in the rotary table device 1 . That is, the turntable device 1 includes a fixed portion 10 , a direct acting portion 20 and a rotating portion 30 .

The fixed part 10 will be described. Referring to FIG. 2, outer cylinder 11 has a cylindrical inner peripheral wall 11a. A coil 41 is fixed to the inner peripheral wall 11a. The coil 41 is spirally wound in multiple layers along the inner peripheral wall 11a, and extends in the axial direction of the inner peripheral wall 11a as a whole. In addition, the coil 41 may be directly fixed to the inner peripheral wall 11a, or may be attached via a support member.

A ball spline nut 51 is fixed to the inner peripheral side of the housing 12 fixed to the first end side of the outer cylinder 11 . The ball spline nut 51 constitutes a ball spline 50 (FIG. 3) as a first bearing mechanism. The ball spline nut 51 supports the first end side of the shaft 21 through balls 53 (FIG. 3) so as to be able to move in the axial direction. A bearing outer ring 13 is fixed to the second end side of the outer cylinder 11 . The bearing outer ring 13 faces the bearing inner ring 32 .

The direct acting portion 20 will be described. Referring to FIG. 2 , shaft 21 is a shaft-like member extending through outer cylinder 11 . The axial direction of the shaft 21 is the same as the axial direction of the inner peripheral wall 11 a of the outer cylinder 11 . In other words, the shaft 21 extends in the same axial direction as the inner peripheral wall 11 a of the outer cylinder 11 . A magnetic field 42 is fixed near the center of the shaft 21 in the axial direction. The field magnet 42 is formed by arranging a plurality of ring-shaped permanent magnets fitted on the shaft 21 in the axial direction. As is well known, the plurality of permanent magnets are arranged with alternating north and south poles. A magnetic field 42 is provided at a position facing the coil 41 . The shaft 21 has a flange portion 22 which is a portion projecting outward like a collar. The field magnet 42 is clamped and fixed by the flange portion 22 and the nut 23 which is a bearing nut. Field magnet 42 and nut 23 are fixed to shaft 21 . The coil 41 and the magnetic field 42 constitute the motor mechanism 40 .

A second end side of the shaft 21 is supported by a ball screw nut 61 via a ball 63 (FIG. 3). The second end of the shaft 21 passes through the hollow portion of the inner circumference of the bearing inner ring 32 and reaches the hollow portion of the inner circumference of the table 31 . Since the shaft 21 moves linearly in the axial direction, it is preferably designed so that the shaft 21 does not protrude from the main surface 31a of the table 31 when the shaft 21 is moved to the second end side to the maximum.

The rotating section 30 will be described. Referring to FIG. 2, rotating portion 30 includes a ball screw nut 61, a bearing inner ring 32, and a table 31, which are fixed to each other. The ball screw nut 61 is connected to the shaft 21 via the balls 63 (FIG. 3), as described above. Further, the bearing inner ring 32 is rotatably connected to the bearing outer ring 13 via rollers 33 (FIG. 3). The rotating portion 30 is rotatable, and at the same time, is axially immovable because it is connected to the bearing outer ring 13 that constitutes the fixed portion 10 .

A structure for connecting the fixed portion 10, the direct acting portion 20, and the rotating portion 30 will be described with reference to FIG. A ball spline 50 as a first bearing mechanism is configured between the fixed portion 10 and the shaft 21 that constitutes the linear motion portion 20 . A spline groove 52 extending in the axial direction is formed in the outer peripheral surface of the shaft 21 on the first end side. A ball 53 is inserted in a raceway formed between the ball spline nut 51 and the spline groove 52 . The ball spline 50 shown in FIG. 3 is a schematic diagram conceptually showing the configuration, and does not necessarily reflect the actual dimensions and shape. In the example shown in FIG. 3, the ball spline 50 is provided as the first bearing mechanism. For example, a slide bearing may be used instead of the ball spline. When using a ball spline, there is an advantage that it is possible to receive the rotational reaction force received from the rotating part 30, and it is possible to suppress idle rotation of the shaft.

Referring to FIG. 3 , a ball screw mechanism 60 is provided between shaft 21 forming linear motion portion 20 and rotating portion 30 . A spirally extending ball screw groove 62 is formed on the outer peripheral surface of the shaft 21 on the second end side. A ball 63 is inserted in a raceway formed between the ball screw nut 61 and the ball screw groove 62 . The ball screw mechanism 60 shown in FIG. 3 is a schematic diagram conceptually showing the configuration, and does not necessarily reflect the actual dimensions and shape. By connecting the linear motion part 20 and the rotary part 30 with the ball screw mechanism, the energy loss is small, and the linear motion of the linear motion part 20 can be efficiently converted into the rotary motion of the rotary part 30. . Also, the rotational speed and amount of rotation of the rotating portion 30 can be designed by selecting the lead. In addition, it is possible to increase rigidity and reduce backlash by selecting the size of the ball. There is also a possibility that the existing knowledge of ball screws can be used for durability and the like.

Referring to FIG. 3, a cross roller bearing 70 as a second bearing mechanism is provided between fixed portion 10 and rotating portion 30 . The cross roller bearing 70 includes a bearing outer ring 13 that constitutes the fixed portion 10, a bearing inner ring 32 that constitutes the rotating portion 30, and rollers 33 inserted in a raceway formed between the bearing outer ring 13 and the bearing inner ring 32. and including. The cross roller bearing 70 shown in FIG. 3 is a schematic diagram conceptually showing the configuration, and does not necessarily reflect the actual dimensions and shape. In addition, although the cross roller bearing 70 is provided as the second bearing mechanism in the example shown in FIG. For example, an angular bearing or a normal ball bearing may be used in place of the cross roller bearing, or a slide bearing may be used depending on the application and dimensions. When a cross roller bearing is used, high rigidity can be achieved. Moreover, the cross roller bearing 70 is preferable because it can receive both the axial load received from the shaft 21 and the radial load received from the table 31 . Further, positioning accuracy can be further improved by using a highly accurate cross roller bearing together with an encoder.

The operation of the rotary table device 1 will be described with reference to FIG. The rotary table device 1 has a motor mechanism 40 . The motor mechanism 40 includes a coil 41 fixed to the inner peripheral wall 11 a of the outer cylinder 11 and a magnetic field 42 fixed to the outer peripheral surface of the shaft 21 at a position facing the coil 41 . The field magnet 42 is formed by inserting ring-shaped magnets into the shaft 21 and arranging them in a plurality of axial directions. When a current flows through the coil 41, which is the stator of the motor mechanism 40, axial thrust is generated to move the shaft 21 in the axial direction. By switching the direction of the current flowing through the coil 41, the shaft 21 can be reciprocated. Also, by changing the amount of current, the output of the motor 40 can be controlled to control the moving speed of the shaft 21 .

Linear motion of the shaft 21 is transmitted to the ball screw nut 61 . Since the ball screw nut 61 is restricted in axial movement, only rotational movement occurs. Since the table 31 is fixed to the ball screw nut 61 , the table 31 rotates together with the ball screw nut 61 . The amount of rotation of the table 31 correlates with the amount of movement of the shaft 21 . The rotation angle of table 31 depends on the lead of ball screw groove 62 (FIG. 3). In the rotary table device 1, the lead of the ball screw groove 62 provides a rotary table device having an arbitrary rotation angle. For example, it may be a rotary table device that reciprocates within a fixed angle such as 60°, 120°, or 250°, or a rotary table device that rotates 360° or more.

The rotary table device 1 may further include an encoder for detecting the amount of movement. FIG. 5 is a cross-sectional view of rotary table device 101 according to the second embodiment. FIG. 6 is a cross-sectional view of a rotary table device 201 according to Embodiment 3. FIG. FIG. 7 shows a rotary table device 301 according to the fourth embodiment. Each of the rotary table devices 101, 201, and 301 has an encoder, and the position where the encoder is installed is different. 5 to 7, the same components as those of the rotary table device 1 are denoted by the same reference numerals, and part of the description is omitted.

Referring to FIG. 5, rotary table device 101 includes rotary scale 81 on the outer peripheral surface of the shaft portion of table 31 . An encoder head 82 is provided facing the rotary scale 81 . The encoder head 82 is fixed to the outer cylinder 11 via a bracket 83 . A rotary scale 81 and an encoder head 82 constitute an encoder 80 . With such an arrangement, the rotation of the table 31 can be detected directly, so that the rotation can be controlled more accurately and the positioning can be performed.

Referring to FIG. 6 , rotary table device 201 includes rotary scale 81 on the outer peripheral surface of the shaft portion of ball screw nut 61 . An encoder head 82 is provided facing the rotary scale 81 . The encoder head 82 is fixed to the outer cylinder 11 . A rotary scale 81 and an encoder head 82 constitute an encoder 80 . With such a configuration, the rotation of the ball screw nut 61 that rotates together with the table 31 can be detected, so the rotation can be controlled more accurately and positioning can be performed. In addition, since the rotary scale 81 and the detection portion of the encoder head 82 are housed inside the outer cylinder 11, the adhesion of dust is prevented, resulting in excellent durability and operational stability.

Referring to FIG. 7, rotary table device 301 includes rotary scale 81 on the outer peripheral surface of shaft 21 . An encoder head 82 is provided facing the rotary scale 81 . Encoder head 82 is fixed to housing 12 . A rotary scale 81 and an encoder head 82 constitute an encoder 80 . With such a configuration, the members protruding in the radial direction of the rotary table device 301 can be reduced, and a smaller rotary table device can be configured.

The rotary table apparatus according to the present disclosure can have various configurations in place of or in addition to the specific embodiments described above. For example, the motor mechanism is not limited to linear motors as long as the desired accuracy and output are obtained. For example, the shaft may be axially reciprocated by a hydraulic cylinder or the like. Further, the shape of the main surface of the table is not limited to an annular surface with an open center, and may be a disc shape without a hollow portion. Another member may be attached to the main surface of the table. The main surface of the table is not limited to a flat surface, and may be provided with protrusions or steps. That is, the table may have other functions instead of the function of placing and rotating an object, or in addition to the function of placing and rotating an object. For example, the rotary table device according to the present disclosure can be used as a hand of a manipulator to rotate hand parts attached to a table. Regarding the shape of the shaft, in the above embodiment, the spline groove was formed on the first end side of the shaft, the flange portion was formed on the central portion, and the ball screw groove was formed on the second end side. A specific shape is not limited to this.

The rotary table device according to the present disclosure is particularly suitable as a small-diameter rotary table device. Specific dimensions are not particularly limited, but for example, the outer diameter of the rotary table can be set to about 30 to 80 mm, and the outer diameter of the housing (fixed portion) can be set to the same extent.

It should be understood that the embodiments disclosed this time are illustrative in all respects and not restrictive in any aspect. The scope of the present invention is defined by the scope of the claims rather than the above description, and is intended to include all changes within the meaning and scope of equivalence to the scope of the claims.

Reference Signs List 1, 101, 201, 301 rotary table device 10 fixed portion 11 outer cylinder 11a inner peripheral wall 12 housing 13 bearing outer ring 20 direct acting portion 21 shaft 22 flange portion 23 nut 30 rotating portion 31 Table, 31a Main Surface, 32 Bearing Inner Ring, 33 Roller, 40 Motor Mechanism, 41 Coil, 42 Field, 50 Ball Spline, 51 Ball Spline Nut, 52 Spline Groove, 53, 63 Balls, 60 Ball Screw Mechanism, 61 Ball Screw Nut, 62 ball screw groove, 70 cross roller bearing, 80 encoder, 81 rotary scale, 82 encoder head 83 bracket.

Claims (6)

a housing having a cylindrical inner peripheral wall;
a shaft passing through the housing and extending in an axial direction common to the axial direction of the inner peripheral wall;
a first bearing mechanism that supports the first end side of the shaft so as to be directly movable with respect to the housing;
a motor mechanism that reciprocates the shaft in the axial direction of the shaft;
a rotating body connected to the shaft via a ball screw mechanism provided on a second end side opposite to the first end side of the shaft;
with
the rotating body is rotatably supported with respect to the housing via a second bearing mechanism, and includes a ball screw nut and a table fixed to each other;
rotary table device. The motor mechanism is
a coil fixed to the inner peripheral wall of the housing;
a magnetic field fixed at a position facing the coil on the outer peripheral surface of the shaft;
including,
2. The rotary table apparatus according to claim 1. the first bearing mechanism is a ball spline mechanism,
A ball spline nut is fixed to the housing,
A spline groove is formed on the outer peripheral surface of the shaft on the first end side,
3. The rotary table device according to claim 1 or 2. the second bearing mechanism is a cross roller bearing;
A bearing outer ring of the cross roller bearing is fixed to the housing,
The bearing outer ring and the bearing inner ring fixed to the ball screw nut and the table are connected via rollers.
The rotary table apparatus according to any one of claims 1 to 3. The magnetic field includes a magnet row in which a plurality of annular permanent magnets inserted into the shaft are arranged in the axial direction,
The shaft is provided with a flange portion in contact with the magnetic field at one end of the portion where the magnetic field is arranged,
The magnetic field is clamped and fixed by the flange portion and a nut fitted on the shaft,
The rotary table device according to any one of claims 1 to 4. It also has an encoder,
The encoder is
a scale attached to the outer peripheral surface of the rotating body;
an encoder head attached to the housing and facing the scale;
including,
6. The rotary table apparatus according to any one of claims 1 to 5.

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