JP2003232424A - Linear-motion shaft device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear-motion shaft device capable of being mounted on a linear-motion table device, etc., without receiving spatial restriction. <P>SOLUTION: A circulating passage forming means 38 to form a circulating passage of a ball 36 is constituted of a through hole 40 formed on a ball screw shaft 28 along the axial direction of the ball screw shaft 28 and return guide passage forming means 42A, 42B to form a return guide passage of the ball 36 between this ball circulating hole 40 and a ball rolling passage 34. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion shaft device used as means for driving a linear motion table of a linear motion table device, and more particularly to a linear motion shaft device using a circulating ball screw.

[0002]

2. Description of the Related Art Conventionally, a linear motion shaft device of this type is rotatably supported by a housing having a cylindrical shape, a radial bearing provided in the housing, and the radial bearing. A ball nut, a ball screw shaft having a spiral groove on the outer peripheral surface facing the spiral groove formed on the inner peripheral surface of the ball nut, and a ball rolling shaft formed between the ball screw shaft and the spiral grooves of the ball nut. The ball screw shaft is provided with a large number of balls rolling on a running path and a motor for rotationally driving the ball nut. When the rotational torque of the motor is transmitted to the ball nut, the ball screw shaft moves back and forth in the axial direction.

[0003]

Such a linear motion shaft device can be used as a linear motion output shaft unit for handling such as an assembling machine, but it has the following problems. That is, in the above-described linear motion shaft device, the ball circulation path is provided on the ball nut side, and therefore, when the motor is arranged at a position offset from the ball screw shaft, it is compact. It had a problem that design becomes difficult. Further, since the outer diameter of the ball nut and the drive unit including the motor are large in the radial direction of the ball screw shaft, there is a problem that space is restricted when the ball nut is attached to the device. .

The present invention has been made in view of the above problems, and an object of the present invention is to enable a compact design and to mount the apparatus on a device without being restricted in space. It is to provide a linear motion output shaft device that can be performed.

[0005]

In order to achieve the above-mentioned object, a linear drive device according to the present invention has a cylindrical housing, a radial bearing provided in the housing, and a radial bearing. A ball nut rotatably supported by the housing via a bearing, a ball screw shaft having a spiral groove formed on the inner peripheral surface of the ball nut, the spiral groove facing the spiral groove on the outer peripheral surface, and the ball screw shaft. A direct-acting shaft device comprising a plurality of balls rolling in a ball rolling path formed between both spiral grooves of the ball nut, wherein the ball nut is a rotation input, and the ball screw shaft is It has a circulation path forming means for forming a ball circulation path,
The circulation path forming means forms a through hole formed in the ball screw shaft along the axial direction of the ball screw shaft, and a return guide path for the ball between the through hole and the ball rolling path. And a return guide path forming means.

In the linear motion shaft device according to the present invention, since it is not necessary to provide a ball circulation path on the ball nut side, a compact design is possible even when the motor is arranged at a position offset from the ball screw shaft. Moreover, since the outer diameter can be reduced, there is no space limitation when mounting the device. In the linear motion shaft device according to the present invention, as a method of rotationally driving the ball nut, as in the invention of claim 2, the ball nut is connected to the rotary input shaft extending from one end via a coupling. One using a motor having a motor shaft is conceivable. Also,
As in the third aspect of the invention, a built-in motor including a stator fixed to the inner surface of the housing and a rotor fixed to the outer surface of the ball nut facing the stator may be used. In any case, as the direct-acting output shaft, an output shaft extending from one end of the ball screw shaft is provided as in the invention of claim 4, and the linear output shaft is directly attached to the housing so as to be movably supported in the axial direction. A feature is that a dynamic guide bearing is arranged.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention. 1, a linear motion shaft device 10 according to a first embodiment of the present invention includes a housing 12 formed in a tubular shape (for example, a cylindrical shape), a radial bearing 14 provided in the housing 12, and a radial bearing 14 provided in the housing 12. A ball nut 16 rotatably supported by the housing 12 via a radial bearing 14 and a motor 18 for rotationally driving the ball nut 16 are provided, and a motor shaft 181 of the motor 18 has a ball nut 16 of the ball nut 16. A rotary input shaft 20 extending from one end is connected via a coupling 22.

Further, the direct acting shaft device 10 includes a ball nut 16
Spiral groove 26 facing the spiral groove 24 formed on the inner peripheral surface of the
Ball screw shaft 28 having an outer peripheral surface and an output shaft (spline shaft) 30 extending from one end of the ball screw shaft 28.
And a ball spline 32 as a linear guide bearing for movably supporting the output shaft 30 in the axial direction is attached to the inner surface of the housing 12. In addition,
On the output shaft 30, a spline groove 31 that engages with the ball of the ball spline 32 is formed along the axial direction of the output shaft 30.

Further, the direct acting shaft device 10 is a ball nut 1.
6 and a large number of balls 36 rolling in a ball rolling passage 34 formed between the spiral grooves 24 and 26 of the ball screw shaft 28. The ball screw shaft 28 is provided with a circulation passage for the balls 36. The circulation path forming means 38 is provided.
The circulation path forming means 38 includes a through hole 40 formed in the ball screw shaft 28 along the axial direction of the ball screw shaft 28, and a ball 36 between the through hole 40 and the ball rolling path 34.
Return guide path forming means 4 for forming the return guide path
2A, 42B, and return guide path forming means 42
As shown in FIG. 2, A and 42B are composed of a return guide member 44 and an end cap member 46.
In the present embodiment, the through hole 40 is the ball screw shaft 28.
Is formed on the shaft core part.

The return guide member 44 is the ball screw shaft 2
8 is formed in a columnar shape with substantially the same diameter as that of 8, and the ball 36 is formed on the outer peripheral surface of the return guide member 44 through the return guide hole 44b formed inside the return guide member 44 and into the through hole 40. Lead guide groove 4
4a is formed in a spiral shape. The return guide member 44 is fixed to the end surface of the ball screw shaft 28 by a plurality of setscrews 48 (see FIG. 3), and the return guide member 44 has a plurality of threaded screws for passing the set screws 48. The hole 44c (see FIG. 2) has the return guide member 4
4 is provided along the axial direction. Further, the return guide member 44 has a plurality of positioning projections 44d on the end surface on the side fixed to the ball screw shaft 28, and these positioning projections 44d are positioned in the positioning holes formed on the end surface of the ball screw shaft 28 (see FIG. When fitted in (not shown), the return guide member 44 is positioned at a predetermined position with respect to the ball screw shaft 28.

The end cap member 46 is a cylindrical portion 46a fitted to the outer peripheral surface of the return guide member 44 (see FIG. 2).
A return guide groove 46b (see FIG. 3) that forms a return guide path with the return guide groove 44a is spirally formed on the inner peripheral surface of the cylindrical portion 46a. In addition, the end cap member 46 is the cylindrical portion 4
6a has an end plate portion 46c that closes one end thereof. The end plate portion 46c has a plurality of mounting holes 46d (see FIG. 2) for mounting the end cap member 46 to the return guide member 44 with the set screw 48. (See) has been drilled. The end cap member 46 of the return guide path forming means 42A is formed integrally with the output shaft 32, as shown in FIG.

In such a structure, when the rotational torque of the motor 18 is transmitted to the ball nut 16 via the coupling 22 and the rotary input shaft 20, the ball screw shaft 28 moves forward and backward in the axial direction and the ball 36 rolls. Runway 3
Roll 4 At this time, the ball 36 rolling on the ball rolling path 34 is returned to the return guide path forming means 42A (or 4).
2B) passes through the return guide passage formed between the return guide grooves 44a and 46b, enters the through hole 40, and rolls in the through hole 40 in one direction. Then, the ball 36 exiting from the through hole 40 enters the return guide path formed between the return guide grooves 44a and 46b of the return guide path forming means 42B (or 42A), and the ball rolling path 34 passes through this return guide path. Will be guided to.

Therefore, the linear motion shaft device 10 according to the present embodiment.
Since the circulation path for the balls 36 does not have to be provided on the ball nut side, the outer diameters of the housing 12 and the ball nut 16 can be made small, which allows the device to be mounted on the device without being restricted in space. It can be performed. When a ball screw that circulates balls on the ball nut side is used in a nut rotation method, the rotation input motor is arranged at a position offset from the ball nut, whereas in the present embodiment, Since it becomes possible to dispose the rotation input motor 18 coaxially with the ball screw shaft 28 on the end surface of the nut 16, as compared with the conventional one in which the rotation input motor 18 is disposed at a position offset from the ball nut 16. A compact design is possible.

Further, if used as a substitute for an air cylinder or the like, it can be used as an input / output shaft excellent in high acceleration / deceleration performance. If the ball screw shaft 28 is a multi-thread screw shaft, the load capacity can be increased. Furthermore, if a small coaxial feed mechanism is configured using the linear motion shaft device 10 according to the present embodiment, it can be applied to a high density mounting machine as well as a small Stewart platform (parallel mechanism). In addition, various applications are conceivable as a linear motion output shaft unit other than a table.

Next, a second embodiment of the present invention is shown in FIG. In the figure, a linear motion shaft device 50 according to a second embodiment of the present invention includes a housing 12 formed in a tubular shape (for example, a cylindrical shape), a radial bearing 14 provided in the housing 12, and a radial bearing 14 provided in the housing 12. A ball nut 16 rotatably supported on the housing 12 via a radial bearing 14;
Built-in motor 19 for rotating the ball nut 16
The built-in motor 19 includes a stator 183 fixed to the inner surface of the housing 12 via the motor housing 182, and a rotor 184 fixed to the outer surface of the ball nut 16 so as to face the stator 183. Is configured.

Further, the direct acting shaft device 10 includes a ball nut 16
Spiral groove 26 facing the spiral groove 24 formed on the inner peripheral surface of the
Ball screw shaft 28 having an outer peripheral surface and an output shaft (spline shaft) 30 extending from one end of the ball screw shaft 28.
And a ball spline 32 as a linear guide bearing for movably supporting the output shaft 30 in the axial direction is attached to the inner surface of the housing 12. Further, the linear motion shaft device 10 is provided with a large number of balls 36 that roll in a ball rolling passage 34 formed between the spiral grooves 24 and 26 of the ball nut 16 and the ball screw shaft 28. Is provided with a circulation path forming means 38 that forms a circulation path for the balls 36. The output shaft 30
The spline groove 31 that engages with the ball of the ball spline 32 is formed in the axial direction of the output shaft 30. Further, the circulation path forming means 38 has the same configuration as that of the first embodiment described above, and thus detailed description thereof will be omitted.

In such a configuration, the built-in motor 1
When the rotor 184 of FIG. 9 rotates, the ball nut 16 rotates integrally with the rotor 184, and the ball screw shaft 2
8 moves forward and backward in the axial direction, and the ball 36 rolls on the ball rolling path 34. At this time, the ball 36 rolling in the ball rolling path 34 forms the return guide path formed between the return guide grooves 44a and 46b of the return guide path forming means 42A (or 42B) as in the first embodiment. It passes through the through hole 40 and rolls in the through hole 40 in one direction. Then, the ball 36 exiting from the through hole 40 enters the return guide path formed between the return guide grooves 44a and 46b of the return guide path forming means 42B (or 42A), and the ball rolling path 34 passes through this return guide path. Will be guided to.

Therefore, in the linear motion shaft device 50 according to the second embodiment, the circulation path of the balls 36 does not have to be provided on the ball nut side, so that the housing 12 and the ball nut 1 are provided.
The outer diameter of 6 can be reduced, which allows the device to be attached to the device without being restricted in space, and in the nut rotation system, the built-in motor 19 for rotation input can be installed from the ball nut 16. A compact design is possible as compared with the conventional one that is arranged at an offset position.

A built-in motor 19 for rotating the ball nut 16 is fixed to the inner surface of the housing 12 via a motor housing 182, and a stator 183 is fixed to the outer surface of the ball nut 16 so as to face the stator 183. And the rotor 184, and does not require the rotary input shaft 20 or the coupling 22 as in the first embodiment, the axial dimension can be shortened.

The present invention is not limited to the above embodiment. For example, in the above-described first and second embodiments, the through hole 40 of the circulation path forming means 38 is provided in the shaft core portion of the ball screw shaft 28, but the ball screw shaft 2 is not always required.
It is not necessary to provide the through hole 40 in the shaft core portion of 8. Further, in the above-described first and second embodiments, the ball screw shaft 28 has a single spiral groove formed on the outer peripheral surface of the shaft. However, a multiple spiral groove is formed on the outer peripheral surface of the shaft. The ball screw shaft 28 may be used. Further, in the above-described first and second embodiments, the return guide path forming means 42A, 42B for forming the return guide path of the ball 36 between the through hole 40 and the ball rolling path 34 is provided with the return guide member 44 and the end cap. It consisted of the member 46,
For example, the one in which the return guide member 44 and the end cap member 46 are integrated is used as the return guide path forming means 4
You may use as 2A, 42B.

[0021]

As described above, according to the present invention,
Since the ball circulation path does not have to be provided on the ball nut side, the outer diameters of the housing and the ball nut can be reduced, and thus the ball table can be mounted on the linear motion table device without being restricted in space. A direct drive shaft device can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a linear drive shaft device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a return guide path forming means shown in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a return guide path forming means shown in FIG.

FIG. 4 is a sectional view showing the structure of a linear drive shaft device according to a second embodiment of the present invention.

[Explanation of symbols]

12 housing 14 radial bearing 16 ball nuts 18 motor 181 motor shaft 183 stator 184 rotor 20 rotation input shaft 22 Coupling 24,26 spiral groove 28 Ball screw shaft 30 output shaft 32 ball spline 34 ball rolling track 36 balls 38 Circulation path forming means 40 through holes 42A, 42B Return guide path forming means 44 Return guide member 46 End cap member

Claims (4)

[Claims] 1. A housing formed in a tubular shape, a radial bearing provided in the housing, a ball nut rotatably supported by the housing via the radial bearing, and an inner circumference of the ball nut. A ball screw shaft having on its outer peripheral surface a spiral groove facing the spiral groove formed on the surface, and a large number of balls rolling on a ball rolling path formed between the ball screw shaft and the spiral grooves of the ball nut. And a ball screw shaft having a circulation path forming means for forming a circulation path of the ball, wherein the circulation path forming means comprises: A through hole formed in the ball screw shaft along the axial direction of the ball screw shaft, and a return guide path forming hand for forming a return guide path for the ball between the through hole and the ball rolling path. Linear axis apparatus characterized by being composed of a. 2. The motor for rotationally driving the ball nut has a motor shaft connected via a coupling to a rotary input shaft extending from one end of the ball nut. Linear motion shaft device. 3. A motor for rotating the ball nut, comprising a stator fixed to an inner surface of the housing, and a rotor fixed to an outer surface of the ball nut so as to face the stator. The linear motion shaft device according to claim 1, wherein 4. The linear motion guide bearing which supports an output shaft extending from one end of the ball screw shaft so as to be movable in the axial direction.
A direct acting shaft device according to any one of 1.