JP2887426B2 - Single axis combined motion unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-shaft combined operation unit in which a shaft is axially moved and rotated by two nuts.

[0002]

2. Description of the Related Art An orthogonal XY robot or a scalar type robot is provided with a single-axis composite operation unit for moving and rotating a chuck or a hand in the Z-axis and θ-axis directions at the tip of an arm. As this kind of uniaxial composite operation unit,
The applicant has previously constructed a motor having a spline nut and a ball screw nut as rotor portions as shown in FIG. 4 and directly drives the above-mentioned nuts to rotate directly. Suggested.

That is, in FIG. 4, a screw groove 1a is provided on the outer periphery of the shaft 1 from the substantially central portion to the upper side, and a spline groove 1b parallel to the axis is provided on the lower outer periphery of the shaft 1. , The ball screw nut 3 is engaged with the spline groove 1b, and the spline nut 2 is spaced apart from the spline groove 1b. Further, at the center of the outer periphery of the ball screw nut 3, a rotor portion 4 composed of, for example, an annular permanent magnet whose N and S poles are magnetized in the circumferential direction is disposed.
Are arranged facing each other at a predetermined interval. The upper and lower ends of the stator 5 are sandwiched by a pair of core holders 5a, and the stator 5 and the rotor 4
1 is configured.

[0004] On the other hand, a rotor portion 6 is also provided at the center of the outer periphery of the spline nut 2 and a stator 7 is arranged to face the spline nut 2. The upper and lower ends of the stator 7 are a pair of core holders 7.
a, and constitutes a motor M2 for rotating the spline nut 2 by the stator 7 and the rotor 6 described above. The stators 5 and 7 of the motors M1 and M2 are separately fixed to the inner periphery of a cylindrical housing 8 attached to the arm of the orthogonal XY robot or the SCARA robot. Support bearings 9 and 10 are disposed between the inner peripheral edges of the core holders 5 a and 7 a of the stators 5 and 7 and the ball screw nut 3 and the spline nut 2.

When the motor M1 is driven to rotate, the ball screw nut 3 integral with the motor M1 directly rotates, and the ball screw moves in the screw groove 1a, whereby the shaft 1 moves in the Z-axis direction. On the other hand, when the motor M2 is rotationally driven, the spline nut 2 rotates directly, and this engages with the spline groove 1b to rotate the shaft 1 in the θ-axis direction.

[0006]

However, with the above configuration, the dedicated nuts 2 and 3 are used to move or rotate the shaft 1 in the Z-axis direction and the θ-axis direction. When a large load is applied to the shaft 1 only in the Z-axis direction or only in the θ-axis direction, the ball screw nut 3 or the spline nut 2 receives this load individually. Therefore, in order to operate normally under a high load, each of the nuts 2 and 3 must be provided with the motors M1 and M2 having a performance capable of rotationally driving, and there is a problem that the size is inevitably increased. . When the shaft 1 is moved or rotated independently in the Z-axis direction or the θ-axis direction, one of the motors M1 or M2 must be driven and the other must be in a locked state. There is a problem of generating heat.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has a simple structure that has a large withstand load, can be reduced in size with a simple structure, and can reduce heat generation. It is an object to provide a composite operation unit.

[0008]

Means for Solving the Problems The present invention provides a single-shaft composite including a shaft provided with a spiral screw groove on the outer periphery, and a nut engaged with the screw groove to move the shaft. Operating unit smell
Te, respectively first and second thread groove leads are different are provided on one side and the other side in the shaft, to the first screw groove
A first nut, which is rotationally driven by a first motor, is engaged, and the second screw groove is rotated by a second motor.
And a second nut which is dynamic engaged, the first and second
The nuts are rotated by the first and second motors together.
In addition, axial movement without rotation or axial movement
Various operations such as rotation without movement can be provided .

[0009]

The first and second nuts, each of which is rotationally driven by a motor, are individually engaged with first and second screw grooves provided on one side and the other side of the shaft and having different leads on the other side. The shaft is moved or rotated in the Z-axis direction and the θ-axis direction by cooperatively controlling both the first and second nuts. At this time, since the load on the shaft in the Z-axis direction or the θ-axis direction is distributed to both the first and second nuts, a relatively small load-bearing nut and a motor for rotating the nut can be used. Therefore, the size can be reduced. Further, even when the shaft is moved or rotated in one of the Z-axis direction and the θ-axis direction, since the first and second motors are always rotated, heat generation due to the locked state is eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the uniaxial composite operation unit according to the present invention will be described with reference to the drawings. FIG.
In the outer periphery of the shaft 21, a first screw groove 21a and a second screw groove 21b having different leads are provided on one side and the other side with respect to the center. The first screw groove 21a provided on one side of the shaft 21 has a predetermined lead angle θ1 and the lead pitch l _1. In contrast, the second screw groove 21b provided on the other side of the shaft 21 sets a lead angle θ2 to 2 × .theta.1 with respect to the first screw groove 21a, the lead pitch l ₂ 2 × l is set to ₁ .

A first nut 22 composed of a ball screw nut is engaged with the first screw groove 21a, and a ball matching the lead angle and the lead pitch is fitted to the second screw groove 21b having a different lead. The second nut 23 made of a screw nut is disposed so as to be engaged with the second nut 23 so as to be engaged therewith.
The first nut 22 composed of a ball screw nut has a well-known configuration, and the inside of the first groove 22 surrounded by a cylindrical nut portion 22a and left and right end caps 22b has the above-described screw groove 21.
A number of balls (not shown) circulating a are provided inside, and an outer ring 22d is rotatably provided on the outer periphery of the nut portion 22a via a support bearing 22c. This outer ring 2
An attachment hole 22e is formed in 2d. Also, the second
The nut 23 is similarly configured.

As shown in FIG. 2, a first motor M1 for driving is provided next to the first nut 22 coaxially with the shaft 21, and next to the second nut 23, as shown in FIG. A second motor M2 for driving is provided side by side coaxially with the shaft 21. The first and second motors M1 and M2 are juxtaposed so as to be located between the first and second nuts 22 and 23 which are arranged apart from each other.

The first and second motors M1, M
2, a pair of rotary encoders RE1 and RE2 for accurately detecting the rotation angle of each of the nuts 22 and 23 rotationally driven by these motors,
Again, they are arranged coaxially with the shaft 21. The first motor M1 has a rotor 24, which will be described later, and the first nut 22 and the rotary encoder RE1 are connected to the shaft 2
1 is connected via a first connecting member 36 rotatably disposed on the outer periphery of the first member. Similarly, the rotor portion 27 of the second motor M2, the second nut 23, and the rotary encoder RE2 are also connected via a second connection member 37.

The first motor M1 is provided with a rotor section 24 made of, for example, an annular permanent magnet having N and S poles magnetized in the circumferential direction, integrally with the first connecting member 36. . Further, stator cores 25 are arranged on the outer periphery of the rotor section 24 so as to face each other at a predetermined interval. Stator core 2
5, a plurality of salient poles (not shown) are formed, and a driving coil 26 of each phase is wound around each salient pole. When a predetermined drive current is applied to the drive coil 26 of the stator core 25, the rotor portion 24 is rotationally urged, and the first
The first nut 22 and the rotary encoder RE1 are rotationally driven at a predetermined rotation angle via the connecting member 36 of FIG.

On the other hand, the second motor M2 is configured similarly to the first motor M1, and the second connecting member 37
A rotor unit 27 made of, for example, a permanent magnet is provided integrally with the rotor unit 27. Further, a stator core 28 is disposed on the outer periphery of the rotor portion 27 so as to face the same, and drive coils 29 of each phase are wound around a plurality of salient poles of the stator core 28. By applying a predetermined drive current to the drive coil 29, the rotor portion 27 is urged to rotate, and the second
The second nut 23 and the rotary encoder RE2 are rotationally driven at a predetermined rotation angle via the connecting member 37 of FIG.

The first nut 22 is fitted on the inner periphery of the end face of the stator core 25 of the first motor M1 , and a bolt 38
The cylindrical nut holder 30 and the side plate 31 fixed by the screw are integrally connected by a screw 32. Also,
Also on the end face of the stator core 28 of the second motor M2, the nut nut 33 is fitted on the inner periphery, and the nut holder 33 and the side plate 34 fixed by bolts 39 are integrally connected by screws 35. And nut holder 30,
33 or the side plates 31 and 34 are attached to the arm of the orthogonal XY robot or the scalar robot described above.

Next, the operation of the single-axis composite operation unit having the above configuration will be described. The first nut 22 is configured so that when a predetermined current is applied to the drive coils 26 of each phase of the motor M1, the rotor portion 24 is rotationally urged to rotate in a straight line. On the other hand, the second nut 23 is configured to rotate by Rukoto rotate biasing the rotor portion 27 by the motor M2 as well. The rotation of both the first and second nuts 22 and 23 is coordinated and controlled as a differential operation to move or rotate the shaft 21 in the Z-axis direction and the θ-axis direction.

That is, both screw grooves 21 a and 21 b of the shaft 21
Is set so that the second screw structure 21b is connected to the first screw groove 21.
Set the lead angle θ2 to 2 × .theta.1 with respect to a, because they set the lead pitch l ₂ to 2 × l _1, and the first nut 22 a rotational speed of the second nut 23 2: 1 When the shaft 21 is urged to rotate in the same direction, the shaft 21 does not rotate and moves in the axial direction. To move in the opposite direction the shaft 21 without rotating,
What is necessary is just to urge the first nut 22 and the second nut 23 in the opposite direction at the same rotational speed ratio as above.

When the first nut 22 and the second nut 23 are urged to rotate in the forward direction at the same rotation speed,
The shaft 21 does not move in the axial direction but rotates in the normal rotation direction. Shaft 21
The without axial movement, To rotate in the reverse direction,
What is necessary is just to urge the first nut 22 and the second nut 23 to rotate in the reverse direction at the same rotation speed. The above operation is performed on axis 2
This is a basic operation in which the shaft 1 is moved forward and backward, and is rotated forward and backward. However, it is possible to cause the shaft 21 to perform a complicated operation by urging the nuts 22 and 23 to rotate at an appropriate rotation speed and rotation direction. it can.

In order to obtain such an operation, the first and second motors M1 and M2 are cooperatively driven and controlled. As described above, the rotary encoders RE1 and RE2 are connected to both motors M1 and M2. Are provided, based on the rotation angle signal obtained from the first and second nuts 2.
If the rotational angles of the shafts 2 and 23 are cooperatively controlled using a microcomputer, highly accurate position control of the shaft 21 in the Z-axis and θ-axis directions can be easily achieved. Then, a chuck such as a robot fixed to the lower end of the shaft 21 can be accurately positioned or moved with respect to a work (not shown).

FIG. 3 shows another embodiment of the shaft.
On the outer periphery of the shaft 41, a first screw groove 41a having different diameters on one side and the other side with respect to the center, each having a different lead.
And a second screw groove 41b. The first screw groove 41a provided on one side of the axis 41 a smaller diameter has a predetermined lead angle θ3 and the lead pitch l _3. On the other hand, the second screw groove 41b provided on the other side of the shaft 41 having a large diameter is set at the same lead angle θ4 with respect to the first screw groove 41a, and the lead pitch is set to the same value. l ₄ is set to be different. And the first
The first and second nuts (not shown) that fit the respective lead angles and lead pitches are engaged with the screw groove 41a and the second screw groove 41b. The above-described operation can be performed even when a single-axis composite operation unit is configured using such a shaft 41.

The above-described embodiment is merely an example. The first nut is not limited to a ball screw nut, but may be a general screw and nut configuration. Various modifications can be made without departing from the present invention.

[0023]

As is apparent from the above description, according to the uniaxial combined operation unit of the present invention, the first and second screw grooves provided with different leads on one side and the other side provided on the outer periphery of the shaft. , since a structure for engaging the first and second nut which is rotationally driven by each first motor and the second motor individually, the first and second nut both the
By coordinated control at 1 and a second motor, both
The shaft can be moved or rotated in the Z-axis direction and the θ-axis direction while rotating together . At this time, the load applied to the shaft in the Z-axis direction or the θ-axis direction is caused by the first and second nuts.
Because they are rotating together, they are distributed to both the first and second nuts . As a result, a relatively small load-bearing nut and a motor for rotating the nut can be used, so that the unit can be downsized. Further, even when the shaft is moved or rotated in one of the Z-axis direction and the θ-axis direction, since the first and second motors are always rotated, there is an advantage that heat generation due to the locked state can be reduced. .

[0024]

[Brief description of the drawings]

FIG. 1 is a partially exploded side view showing an embodiment of a uniaxial composite operation unit of the present invention.

FIG. 2 is a sectional view showing the motor-driven single-axis composite operation unit.

FIG. 3 is a side view showing a configuration of a shaft.

FIG. 4 is a cross-sectional view showing a conventional motor-driven single-axis composite operation unit.

[Explanation of symbols]

Reference Signs List 21 shaft 21a first screw groove 21b second screw groove 22 first nut (ball screw nut) 23 second nut (ball screw nut) 24, 27 rotor part 25, 28 stator 36, 37 connecting member M1 First motor M2 Second motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 25/20-25/24 H02K 7/06

Claims (2)

(57) [Claims] 1. A single-shaft compound operation unit comprising a shaft provided with a helical thread groove on its outer periphery and a nut engaged with the thread groove to move the shaft, wherein the shaft has one side and the other. A first and a second thread groove having different leads are provided on each side, and the first thread groove is rotated by a first motor.
A first nut driven to rotate is engaged, a second nut rotationally driven by a second motor is engaged in the second thread groove, and the first and second nuts are First
And rotate with respect to the shaft while rotating with the second motor.
Axial movement without rotation or rotation without axial movement
A single-axis composite operation unit characterized by enabling various operations . The method according to claim 2, wherein the first and second nuts, uniaxial composite according to claim 1, characterized in that integrally connected to the rotor portion of the first and second motors for rotating the respective Operating unit.