JP2003232425A - 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 16 along the axial direction of the ball screw shaft 16 and return guide passage forming means 42A, 42B to form a return guide passage of the ball 36 between this ball circulating passage 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 screw shaft, a ball nut having a spiral groove on the inner peripheral surface facing the spiral groove formed on the outer peripheral surface of the ball screw shaft, and a ball formed between the ball nut and the spiral groove of the ball screw shaft. It is equipped with a large number of balls rolling on a rolling path and a motor for rotationally driving the ball screw shaft.When the rotational torque of the motor is transmitted to the ball screw shaft, the ball nut moves forward and backward in the axial direction. There is.

[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, since the ball circulation path is provided on the ball nut side, the motor is arranged at a position offset from the ball screw shaft as in the nut rotation system. In this case, there is a problem that a compact 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 screw shaft rotatably supported by the housing via a bearing, a ball nut having a spiral groove formed on the outer peripheral surface of the ball screw shaft and facing the spiral groove on the inner peripheral surface, and the ball nut. A direct-acting shaft device comprising a plurality of balls rolling in a ball rolling path formed between both spiral grooves of the ball screw shaft, wherein the ball screw shaft is used as a rotary input, and the ball screw shaft comprises: Has a circulation path forming means for forming a circulation path of the ball,
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 for rotationally driving the ball screw shaft, a motor having a motor shaft connected to the ball screw shaft via a coupling is used as in the invention according to claim 2. It can be used. Further, as in the third aspect of the invention, it is possible to use 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 screw shaft so as to face the stator. it can.
In any case, as the linear motion output shaft, a linear motion guide bearing for movably supporting the ball nut in the axial direction is provided as in the invention of claim 4, so that the linear motion output shaft can be movably supported in the axial direction. The linear guide bearing is arranged in the housing.

[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 screw shaft 16 rotatably supported by the housing 12 via a radial bearing 14 and a motor 18 for rotationally driving the ball screw shaft 16 are provided. The motor shaft 181 of the motor 18 includes the ball screw shaft A rotary input shaft 20 extending from one end of the shaft 16 is connected via a coupling 22.

Further, the direct acting shaft device 10 includes a ball screw shaft 16
Spiral groove 26 facing the spiral groove 24 formed on the outer peripheral surface of the
It has a ball nut 28 having an inner peripheral surface and an output bracket 30 connected to one end of the ball nut 28. The inner surface of the housing 12 supports the ball nut 28 so as to be movable in the axial direction. A ball spline 32 as a linear motion guide bearing is attached. A spline groove 31 that engages with the ball of the ball spline 32 is formed on the outer peripheral surface of the ball nut 28.
Is formed along the axial direction of.

Further, the direct acting shaft device 10 is a ball screw shaft 1.
6 and a ball nut 28 are provided with a large number of balls 36 rolling in a ball rolling passage 34 formed between both spiral grooves 24, 26. The ball screw shaft 16 forms a circulation passage for the balls 36. Circulation path forming means 38 is provided.
The circulation path forming means 38 includes a through hole 40 formed in the ball screw shaft 16 along the axial direction of the ball screw shaft 16 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 has the ball screw shaft 16
Is formed on the shaft core part.

The return guide member 44 is the ball screw shaft 1.
6 is formed in a cylindrical shape having a diameter substantially the same as that of the ball guide 6, 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. Further, the return guide member 44 is fixed to the end surface of the ball screw shaft 16 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 16, and these positioning projections 44d are positioned in the positioning holes formed on the end surface of the ball screw shaft 16 (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 16.

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 rotary input shaft 20 is formed integrally with the end cap member 46 of the return guide path forming means 42B.

In such a structure, when the rotational torque of the motor 18 is transmitted to the ball screw shaft 16 via the coupling 22 and the rotary input shaft 20, the ball nut 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 of the ball 36 does not have to be provided on the side of the ball nut, the outer diameters of the housing 12 and the ball nut 28 can be reduced, 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 nut 28 on one end side of the screw shaft 16, the rotation input motor 18 can be arranged at a position offset from the ball screw shaft 16. In comparison, 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 16 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 screw shaft 16 rotatably supported by the housing 12 via a radial bearing 14;
Built-in motor 19 for rotating the ball screw shaft 16
The built-in motor 19 includes a stator 182 fixed to the inner surface of the housing 12, and the stator 18
2 and a rotor 183 fixed to the outer surface of the ball screw shaft 16 facing each other.

Further, the direct acting shaft device 10 includes a ball screw shaft 16
Spiral groove 26 facing the spiral groove 24 formed on the inner peripheral surface of the
A ball nut 28 having an outer peripheral surface and an output shaft 30 connected to one end of the ball nut 28,
A ball spline 32 is mounted on the inner surface of the housing 12 as a linear motion guide bearing that supports the ball nut 28 so as to be movable in the axial direction. A spline groove 31 that engages with the ball of the ball spline 32 is formed on the outer peripheral surface of the ball nut 28 along the axial direction of the ball nut 28.

Further, the direct acting shaft device 10 is a ball screw shaft 1.
6 and a ball nut 28 are provided with a large number of balls 36 rolling in a ball rolling passage 34 formed between both spiral grooves 24, 26. The ball screw shaft 16 forms a circulation passage for the balls 36. Circulation path forming means 38 is provided.
The circulation path forming means 38 has the same configuration as that of the above-described first embodiment, and thus detailed description thereof will be omitted.

In such a structure, the built-in motor 1
When the rotor 184 of No. 9 rotates, the ball screw shaft 16 rotates integrally with the rotor 184, and the ball nut 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 2 are provided.
The outer diameter of 8 can be made small, which allows the device to be mounted on the device without being restricted in space, and in the nut rotation system, the built-in motor 19 for rotation input is provided with the ball screw shaft 16. A compact design is possible as compared with the conventional one which is arranged at a position offset from.

Further, a built-in motor 19 for rotationally driving the ball screw shaft 16 is fixed to the inner surface of the housing 12, and a stator 182, and a rotor 183 fixed to the outer surface of the ball screw shaft 16 facing the stator 182. Since the rotation input shaft 20 and the coupling 22 are not required unlike the first embodiment, the dimension in the axial direction 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 passage forming means 38 is provided in the shaft core portion of the ball screw shaft 16, but the through hole 40 is not necessarily formed in the shaft core portion of the ball screw shaft 16. There is no need to provide it. Further, in the above-described first and second embodiments, the ball screw shaft 16 has a single spiral groove formed on the outer peripheral surface of the shaft. However, a multi-row spiral groove is formed on the outer peripheral surface of the shaft. The ball screw shaft 16 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.

[0022]

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 screw shaft 18 motor 19 Built-in motor 181 motor shaft 182 stator 183 rotor 20 rotation input shaft 22 Coupling 24,26 spiral groove 28 ball nuts 30 output bracket 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 cylindrical housing, a radial bearing provided in the housing, a ball screw shaft rotatably supported by the housing via the radial bearing, and a ball screw shaft of the ball screw shaft. A ball nut having on its inner peripheral surface a spiral groove facing the spiral groove formed on the outer peripheral surface, and a large number of balls rolling on a ball rolling path formed between the ball nut and both spiral grooves of the ball screw shaft. And a ball screw shaft for rotary input, wherein the ball screw shaft has a circulation path forming means for forming a circulation path of the ball, and the circulation path forming means is A through hole formed in the ball screw shaft along the axial direction of the ball screw shaft, and a return guide path forming means 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 linear drive shaft device according to claim 1, wherein the motor that rotationally drives the ball screw shaft has a motor shaft that is connected to the ball screw shaft via a coupling. 3. A motor for rotating and driving the ball screw shaft includes a stator fixed to an inner surface of the housing, and a rotor fixed to an outer surface of the ball screw shaft so as to face the stator. The linear motion shaft device according to claim 1, which is a die motor. 4. The linear motion shaft device according to claim 1, wherein the housing has a linear motion guide bearing that supports the ball nut so as to be movable in the axial direction.