JPH077885A - Direct-acting equipment - Google Patents

Abstract

PURPOSE:To provide a direct-acting equipment, excellent in maintainability and versatility and having small inertia force, by securing a rotor on one end of a threaded shaft, fitting a stator section onto this end of the threaded shaft with the rotor, and securing the stator section on the side of a base. CONSTITUTION:A ball thread mechanism 20 is provided with a base 24, which supports a threaded shaft 21 comprising the ball thread mechanism in such a way that the threaded shaft is freely rotated. A table 29 is driven by the rotation of the threaded shaft 21 and reciprocates between first and second support walls 24a and 24b in the X direction. A rotor 22 has a rotary shaft 30 whose diameter is larger than that of one end 21a of the threaded shaft 21. A hollow 30a is formed on one end face of the rotary shaft 20, and the end 21a of the threaded shaft 21 is inserted into the hollow 30a. A stator section 23 includes a cylindrical casing 35 one end of which is closed. A stator 36 is secured on the inside surface of the casing 35; the inside diameter of the stator 36 is slightly larger than the outside diameter of a permanent magnet 32 installed around the rotary shaft 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion device used for a positioning device such as an XY table.

[0002]

2. Description of the Related Art For example, an XY table device for positioning and driving a semiconductor device, a substrate or the like is a linear motion device in the X direction and a Y motion device.
Directional linear motion device. These linear motion devices are configured to feed and drive a mounting table movable in the X direction or the Y direction by a ball screw mechanism.

An example of such a linear motion device is generally shown in FIG. In the figure, 1 is a ball screw mechanism. The ball screw mechanism 1 includes a screw shaft 3 whose both ends are rotatably held by a pair of bearing devices 2 and 2, and a plurality of steel balls (not shown) in the middle of the screw shaft 3. And a mounting table 5 which is fixed to the nut 4 and is slidably guided in a direction (X direction) shown by an arrow in the drawing. Further, one end of the screw shaft 3 has a flexible coupling 6 (or a flexible joint).
Is connected on the same axis as the drive shaft 7a of the drive motor 7.

Therefore, when the driving motor 7 operates, the screw shaft 3 is rotationally driven through the coupling 6, and the nut 4 moves along the screw shaft 3, and The table 5 is reciprocally driven in the X direction.

However, with such a structure, since the drive shaft 7a of the drive motor 7 and the screw shaft 3 are connected by the coupling 6, the drive shaft 7a is connected at this portion. The mounting table 5 is eccentric due to the displacement of the shaft center between the screw shaft 3 and the screw shaft 3, and the rotation of the driving motor 7 is delayed due to the loss in the coupling 6, and the ball mechanism 1 May be transmitted to.

Further, since there is the coupling 6, the rotational inertial force is large and the responsiveness of acceleration and deceleration may be poor. In order to solve such a problem, the coupling may be eliminated and the drive shaft 7a and the screw shaft may be directly connected. As such a proposal, there is a conventional Japanese Unexamined Patent Publication
There are configurations disclosed in Japanese Patent Application Laid-Open No. 09258 and Japanese Patent Application No. 63-78739.

As shown in FIG. 5 (the structure disclosed in JP-A-1-109258), these structures have a coupling shaft 10 formed by integrally forming a screw shaft and a motor drive shaft.
It is equipped with. That is, a screw portion 10a is formed at one end of the coupling shaft 10 and a nut 12 for holding the mounting table 11 is screwed thereto, and the other end 10b is a case of the motor 13.
A rotor 16 which is housed in the casing 14 and faces a stator 15 provided in the casing 14 is formed. The middle part of the connecting shaft 10 is the case of the motor 13.
It is rotatably held by a bearing device 17 provided on the sing 14.

Therefore, according to such a structure, the problems such as the eccentricity, the time loss, the inertial force and the like which are caused by the existence of the coupling 6 in the structure shown in FIG. 4 are solved.

[0009]

By the way, the mechanism shown in FIG. 5 has the following problems. First, there is a problem in terms of maintainability. For example, if the permanent magnet of the rotor 16 is chipped or the screw portion 10a is damaged or worn during use, it is necessary to remove the coupling shaft 10 for repair.

However, when removing the connecting shaft 10, it is necessary to remove the entire connecting shaft 10.
This is troublesome because it is necessary to remove the bearing device 17 that holds the middle part of the coupling shaft 10.

Second, there is a problem in versatility. For example, when it is desired to change only the driving performance without changing the mechanism of the screw portion 10a, the nut 12 and the mounting table 11, if the structure has the coupling 6 as shown in FIG. It suffices to replace the rotor 7 with another model, but as described above, the screw portion 10a and the rotor 16 are used.
When the joint shaft 10 in which and are integrated is adopted, the whole joint shaft 10 may have to be newly formed and replaced.

Third, there is the problem of inertial force. That is,
The portion of the coupling shaft 10 where the rotor 16 is provided does not have to be solid, and if it is made hollow and light, the inertial force is reduced and the response can be improved.

However, a threaded portion 10a is provided at one end of the coupling shaft 10 and a rotational position detector (18 in FIG. 5) is provided at the other end.
It may not be possible to form this part in the hollow. Further, since the screw portion 10a is required to have wear resistance and rigidity, it may be necessary to manufacture the coupling shaft 10 using an iron-based material. Therefore, the inertial force may not be reduced as expected.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a linear motion device having good maintainability, excellent versatility, and small inertial force.

[0015]

The first means of the present invention is a base and a rotatably held by the base, and
A screw shaft whose one end projects from one side surface of the base by a predetermined amount, and a screw shaft that is slidably held on the base and screwed to the screw shaft. A movable body to be driven, a rotor portion detachably fixed to one end portion of the screw shaft, and one end of the screw shaft and the rotor portion are externally inserted and fixed to one side surface of the base. Thus, the motor is provided with the rotor portion and a stator portion that constitutes a drive motor for rotationally driving the screw shaft.

The second means is the same as the first means,
The rotor portion has a hollow portion into which one end of the screw shaft is inserted, and a yoke that is detachably fixed to the one end portion of the screw shaft and is attached to an outer surface of the yoke. And a magnetic material.

A third means is the above first means,
The rotor portion has a hollow portion into which one end of the screw shaft is inserted, and a rotary shaft fixed to one end portion of the screw shaft, and a yoke provided on an outer surface of the rotary shaft. A magnetic material is provided on the outer surface of the yoke, and the material of the rotary shaft is lighter than the material of the yoke and the screw shaft.

[0018]

According to this structure, the rotor portion is fixed to one end portion of the screw shaft, and the stator portion is externally fitted to the one end portion and the rotor portion of the screw shaft and the starter portion is attached. The linear motion device can be assembled by fixing the to the side surface of the base. In addition, the weight of the rotor can be reduced by molding the rotating shaft that constitutes the rotor with a lightweight material.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional view of a linear motion device of the present invention. As shown in the exploded view of FIG. 2, this device has a rotor screw mechanism portion 20 and a rotor portion attached to one end portion 21a of a screw shaft 21 protruding from the ball screw mechanism portion 20. 22 and a stator portion 23 which is externally inserted in the rotor portion 22 and fixed to the ball screw mechanism portion 20.

First, the ball screw mechanism portion 20 will be described. As shown in FIGS. 1 and 2, the ball screw mechanism unit 20 includes a base 24. This base 24
Are first and second support walls 24 that are erected separately in parallel.
a and 24b. A radial ball bearing 25 is provided in the middle of the first support wall 24a in the height direction, and an angular ball bearing 26 is provided in the middle of the second support wall 24b in the height direction. Has been.

On the radial ball bearing 25 and the angular ball bearing 26, a screw shaft 21 constituting a ball screw mechanism is rotatably installed with its axis being horizontal (X direction). And one end 2 of this screw shaft 21
The reference numeral 1a is derived from the angular contact bearing 26 and is provided on the outer surface side of the second support wall 24b so as to project by a predetermined size.

Further, the screw shaft 21 has the screw shaft 2
A nut 28, which constitutes a ball screw mechanism together with 1, is screwed. A mounting table 29, which is provided on the upper surface of the base 24 so as to be slidable in the X direction along the axis of the screw shaft 21, is fixed to the nut 28. Therefore, in the mounting table 29, when the screw shaft 21 is driven to rotate, the space between the first and second support walls 24a and 24b is X.
It is designed to be reciprocally driven in any direction.

Next, the rotor section 22 will be described. As shown in FIG. 2, the rotor portion 22 includes a shaft-shaped rotary shaft 30 having a diameter larger than that of the one end portion 21 a of the screw shaft 21. A hollow portion 30a into which the one end 21a of the screw shaft 21 is inserted is opened at one end surface of the rotary shaft 30. The depth of the hollow portion 30a is formed deeper than the protruding length of the one end 21a of the screw shaft 21, and even after the one end 21a of the screw shaft 21 is inserted,
A hollow portion (indicated by A in FIG. 1) is left in the middle of the longitudinal direction.

The rotating shaft 30 is the screw shaft 21.
Is formed of a ceramic material that is lighter than the material (iron) or the material (iron) of the yoke 31 described later. And
On the outer peripheral surface of the rotary shaft 30, a yoke made of a thin iron is formed.
The yoke 31 is externally fitted, and a permanent magnet 32 (magnetic material) is adhered to the outer peripheral surface of the yoke 31. Further, a step is provided on the other end side of the rotating shaft 30, and the other end 30a of the rotating shaft 30 is formed to have a small diameter.

The rotor portion 22 and the one end portion 21a of the screw shaft 21 of the ball screw mechanism portion 20 have a hollow portion 30 of the rotary shaft 30 at one end portion 21a of the screw shaft 21.
A is coaxially connected by being externally attached, and both are fixed by a push bolt 33 screwed to one end of the rotary shaft 30.

Next, the starter unit 23 will be described. As shown in FIG. 1 and FIG.
Comprises a cylindrical casing 35 having one end closed. A stator 36 having an inner diameter slightly larger than the outer diameter of the permanent magnet 32 provided on the rotating shaft 30 is fixed to the inner peripheral surface of the casing 35.

A rotary encoder 37 is attached to the outer surface of the wall that closes one end of the casing 35. The other end 30a of the rotary shaft 30 of the rotor portion is inserted into the rotor encoder 37. The rotary encoder 37 detects the rotation angle of the other end 30a of the rotary shaft 30 so that the speed and the movement amount (position) of the mounting table in the X direction can be detected. Has become.

On the opening side of the casing 35,
A flange portion 35a that comes into contact with the second support wall 24b is provided. By connecting the flange portion 35a to the second support wall 24b with the bolt 39, the stator portion is fixed to the ball screw mechanism portion 20.

In this state, the inner peripheral surface of the stator 36 provided in the stator portion 23 and the outer surface of the permanent magnet 32 provided in the rotor portion 22 face each other with a predetermined gap. The rotor section 22 is rotationally driven by supplying power to the stator section.

As a result, the screw shaft 21 connected to the rotary shaft 30 of the rotor portion 22 is rotationally driven, and the nut 28 and the mounting table 29 are driven in the X direction. Further, based on the position detection signal and the speed detection signal from the rotary encoder 37, the power supply to the stator portion 23 is controlled and the positioning of the mounting table 29 is controlled.

The outer diameter of the rotary shaft (outer diameter of the permanent magnet), the inner diameter of the stator, the number of windings, etc. are determined by the required driving force and the required positioning accuracy.
The user of the linear motion device can arbitrarily set the performance of the linear motion device by selecting the rotor portion and the starter portion as needed.

Next, the work for changing the performance of the linear motion device will be described with reference to FIG. In this case, the stator portion 23 and the rotor portion 22 are connected to the boat.
It is necessary to remove from the screw mechanism 20. For this purpose, first, the bolt 39 is loosened and the casing 35 is removed.
The (stator portion 23) is removed from the second support wall 24b. Next, the push bolt 3 screwed to the rotating shaft 30.
By loosening 3, the rotary shaft 30 (rotor portion 22) is removed from the one end portion 21a of the screw shaft 21. As a result, the linear motion device is disassembled as shown in FIG.

Next, another stator portion 23 and a rotor portion having different performance from the removed stator portion 23 and rotor portion 22 are attached to the ball screw mechanism portion 20. To do. For this purpose, the rotor portion 22 is first attached to the one end portion 2 of the screw shaft 21 by the reverse operation of the disassembling operation.
After fixing to 1a, the rotor portion 22 is connected to the stator portion 23.
Is externally attached and fixed to the second support wall 24b of the ball screw mechanism section 20.

By these things, the performance of this linear motion device can be changed. It should be noted that the same operation is performed during maintenance and parts replacement, etc.
Also, the stator portion 23 is disassembled and assembled.

According to this structure, the following effects can be obtained. First, the screw shaft 21 of the ball screw mechanism unit 20 and the rotary shaft 30 of the rotor unit 22 are not coupled by using a coupling, but the screw shaft 21 of the screw shaft 21 is provided in the rotary shaft 30. Since the one end portion 21a is fitted in a predetermined size so as to be coaxially coupled, it is possible to prevent the both from being eccentric during rotation. Further, since no coupling is used, the weight can be reduced by that amount, and there is an effect that the inertial force is prevented from increasing.

Secondly, since the connecting portion of the screw shaft 21 of the ball screw mechanism portion 20 and the rotating shaft 30 of the rotor portion 22 is located inside the stator portion 23, the structure is miniaturized. There is an effect that can be achieved.

Thirdly, in the device having the coupling shaft 10 in which the screw portion 10a and the rotor 16 are integrally formed in the conventional example (FIG. 5), the above-mentioned rotor is restricted due to structural and processing restrictions.
While it was not possible to use different materials only for the part where the data 16 was provided or to provide a hollow part inside,
According to the present invention, the inside of the rotary shaft 30 constituting the rotor portion 22 can be made hollow A, and the material of the rotary shaft 30 is different from that of the screw shaft 21 and the yoke 32. Since it is possible to use a lightweight material (for example, a ceramic material), the weight of the rotor portion 22 can be reduced. This has the effect of preventing an increase in inertial force and vibration due to the weight of the rotor portion 22.

Fourthly, in the conventional device, it is necessary to remove the motor 7 and the coupling 6 (FIG. 4) or disassemble the entire device in order to change the performance at the time of maintenance (at the time of maintenance). However, according to the present invention, such an operation is not necessary, and there is an effect that it is easy to secure accuracy during maintenance, disassembly during maintenance, and assembly.

The performance of this linear motion device can be changed by replacing only the stator portion 23 and the rotor portion 22 without changing the ball screw mechanism portion 20. There is also an effect of improving the sex.

The present invention is not limited to the above-mentioned embodiment, but can be variously modified without changing the gist of the invention. For example, the device shown in FIG.
1'is formed to have substantially the same shape as the rotating shaft 30 in the first embodiment.

That is, the yoke 31 'has a hollow portion 31'a into which the one end 21a of the screw shaft 21 is inserted.
It is equipped with. The hollow portion 31'a is formed so that the hollow portion A remains even when one end of the screw shaft 21 is inserted. A push bolt 33 is screwed onto one end of the yoke 31 ', and the one end 21 of the screw shaft 21 of the yoke 31' is fixed to each other by the push bolt 33. .

A permanent magnet 32 is fixed to the outer peripheral surface of the yoke 31 '. Therefore, this yoke 3
1'and the permanent magnet 32 constitute the rotor portion of the present invention.

According to this structure, eccentricity can be prevented as in the first embodiment, and since the hollow A is provided inside, an increase in inertial force can be effectively prevented.

Further, in the above-mentioned one embodiment, the rotating body 30
Although the material of the above is a ceramic material, the material is not limited to this, and other materials such as aluminum alloy and titanium alloy may be used as long as the material is lighter than the yoke 31 and the screw shaft. .

[0045]

As described above, according to the first structure of the present invention, the base is held rotatably on the base, and one end of the base is protruded from one side surface of the base by a predetermined amount. A screw shaft, a movable body slidably held on the base and screwed to the screw shaft, and reciprocally driven by the screw shaft being rotationally driven; and one end portion of the screw shaft. The rotor shaft, which is detachably fixed, is externally inserted to the one end portion and the rotor portion of the screw shaft, and is fixed to one side surface of the base so that the rotor shaft and the screw shaft are fixed together. And a stator portion that constitutes a drive motor for rotationally driving.

The second structure is the same as the first structure.
The rotor portion has a hollow portion into which one end of the screw shaft is inserted, and a yoke that is detachably fixed to the one end portion of the screw shaft and is attached to an outer surface of the yoke. And a magnetic material.

A third configuration is the above first means,
The rotor portion has a hollow portion into which one end of the screw shaft is inserted, and a rotary shaft fixed to one end portion of the screw shaft, and a yoke provided on an outer surface of the rotary shaft. A magnetic material is provided on the outer surface of the yoke, and the material of the rotary shaft is lighter than the material of the yoke and the screw shaft.

First, the screw shaft and the rotor portion are not coupled by using a coupling, but one end portion of the screw shaft is fitted into the rotary shaft of the rotor portion by a predetermined size. Since they are connected coaxially, they are prevented from being eccentric during rotation. Further, since no coupling is used, the weight can be reduced by that amount, and there is an effect that the inertial force is prevented from increasing.

Secondly, since the connecting portion of the screw shaft and the rotating shaft of the rotor portion is located inside the stator portion, there is an effect that the structure can be simplified and the size and weight can be reduced. Thirdly, the inside of the rotary shaft that constitutes the rotor portion can be made hollow, and the material of this rotary shaft is made of a lightweight material (for example, a ceramic material) different from that of the screw shaft and the yoke. Therefore, the weight of the rotor can be reduced. This has the effect of preventing an increase in inertial force and vibration due to the weight of the rotor portion.

Fourth, unlike the conventional device, there is no need to remove the coupling or disassemble the entire device at the time of maintenance (at the time of maintenance) or when changing the performance.
This has the effect of making it easier to ensure accuracy during maintenance, disassembly during maintenance, and assembly.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is likewise an exploded vertical sectional view.

FIG. 3 is a vertical cross-sectional view showing another embodiment.

FIG. 4 is a schematic configuration diagram showing a first conventional example.

FIG. 5 is a vertical sectional view showing a second conventional example.

[Explanation of symbols]

24 ... Base, 21 ... Screw shaft, 21a ... One end, 29 ... Mounting stand (moving body), 22 ... Rotor part, 23 ... Stater part,
30 ... Rotating body, 30a ... Hollow part, 31 ... Yoke, 32 ...
Permanent magnet (magnetic material), 31 '... Yoke, 31'a ... Hollow part.

Claims (3)

[Claims] 1. A base, a screw shaft rotatably held by the base, and a screw shaft whose one end projects from one side surface of the base by a predetermined amount, and slidably held by the base. And a rotor which is screwed to the screw shaft and is reciprocally driven by rotationally driving the screw shaft, a rotor portion detachably fixed to one end of the screw shaft, and the screw shaft. And a rotor portion which is externally inserted into one end portion and a rotor portion and fixed to one side surface of the base to constitute a drive motor for rotationally driving the screw shaft together with the rotor portion. A linear motion device comprising: 2. A rotor having a hollow portion into which one end of the screw shaft is inserted, the yoke being detachably fixed to the one end of the screw shaft, and the yoke of the yoke. The linear motion device according to claim 1, further comprising a magnetic body attached to an outer surface of the linear motion device. 3. The rotor portion has a hollow portion into which one end of the screw shaft is inserted, the rotary shaft fixed to one end portion of the screw shaft, and the outer surface of the rotary shaft. It is composed of a yoke and a magnetic material provided on an outer surface of the yoke, and the material of the rotary shaft is lighter than the material of the yoke and the screw shaft. Item 1. A linear motion device according to item 1.