JP2014170497A - Linear drive introduction unit - Google Patents

Abstract

A linear drive introducer capable of realizing a highly accurate linear motion without using a chain drive is provided.
A bellows 21 that can be stretched and held in a vacuum, a flange 22 that is attached to the stretchable end of the bellows, a plurality of linear guides 25 that are guided at equal intervals around the bellows, and the bellows A linear drive introducer comprising a plurality of moving plates 27 that are individually driven by a plurality of feed screws at equal intervals around the center, and a plurality of motors 32 that individually rotate and drive the plurality of feed screws, The flanges are attached to the plurality of moving plates, and the plurality of moving screws are individually driven to rotate by the plurality of motors, whereby the plurality of moving plates are individually driven linearly to advance and retract the flanges.
[Selection] Figure 3

Description

  The present invention relates to a transfer device for linear movement from the atmosphere side to the vacuum side, and in particular, since it can have a hollow structure, position control of detectors, optical elements, materials, etc. used in a vacuum is possible. It relates to a linear drive introducer and the like.

  A linear drive introducer is used as a transfer machine for linear movement from the atmosphere side to the vacuum side. In the prior art, a method has been used in which a bellows capable of expanding and contracting a movable plate and capable of holding a vacuum is guided by a linear guide and linearly driven by a feed screw. In this method, since the feed screw is located outside the bellows, a load due to a differential pressure is applied to the center of the moving plate, and a moment is generated between the moving plate and the feed screw. As a result, a bending reaction force is applied to the linear guide, and smooth linear driving cannot be performed.

As a conventional technique for preventing the above moment from occurring, in Patent Document 1 (Japanese Patent Laid-Open No. 60-47357), a cylindrical cam is attached to the outside of a linear guide instead of a feed screw, and the groove of the cylindrical cam is attached. By sliding a knob attached to the moving plate, the moment is not generated between the moving plate and the feed screw. As a result, smooth linear driving can be performed without applying a bending reaction force to the linear guide.
Patent Document 2 (Japanese Patent Laid-Open No. 6-163668), Patent Document 3 (Japanese Patent Laid-Open No. 10-313036), Patent Document 4 (Japanese Patent Laid-Open No. 2004-214527), Patent Document 5 (Japanese Patent No. 4981954). ) Has a structure that does not generate a moment by eliminating the pressure difference between the vacuum and the atmosphere applied to the moving plate. Specifically, a rigid fixed plate is connected to the front and rear of the moving plate with a linear guide, and the two fixed plates and the moving plate are connected to the front and rear of the moving plate with separate bellows so that no differential pressure is applied to the moving plate. It has a structure.
In addition, a linear drive introducer having a structure in which feed screws are concentrically arranged at equal intervals around a bellows in order to cancel the moment is also used as an existing technology. An example is shown in FIGS. 1 and 2 (horizontal in FIG. 1). (Cross sectional view) This linear drive linear introducer has a hollow structure and is a transfer device for linearly moving the device from the atmosphere side to the vacuum side. The linear guides 5a, 5b, and 5c and the feed screws 4a, 4b, and 4c are structured so as to be concentrically arranged at equal intervals around the bellows 3. Each feed screw is connected by a chain 9, and one feed screw is rotated by a motor 12 to simultaneously feed through sprockets 6 a, 6 b, 6 c (reference numeral 6 a is not shown) connected to the feed screw. It has a structure that drives a screw. In order to eliminate interference with the bellows, idlers 7a, 7b and 7c are incorporated in the linear guide. By incorporating feed screws at equal intervals, the moment generated between the feed screw and the bellows can be canceled. 1 is a flange, 10 is a wheel gear, 11 is a worm gear, 13 is a coupling, 14 is a worm gear mounting plate, and 15 is a motor mounting plate.

JP 60-47457 A JP-A-6-163668 Japanese Patent Laid-Open No. 10-313036 JP 2004-214527 A Japanese Patent No. 4981954

In Patent Document 1, a torsional force is generated in the linear guide due to friction between the groove in the cylindrical cam and the knob, and accurate linear movement cannot be performed. In addition, since the groove interval of the cylindrical cam cannot be reduced, high-precision linear movement cannot be performed. Furthermore, since the linear guide is incorporated outside the bellows and the outer cylindrical cam is incorporated, it is difficult to reduce the size of the apparatus.
In patent documents 2-5, in order to connect the front and back of a movable part with the bellows which can be expanded and contracted, it cannot be set as a hollow type structure. Therefore, it cannot be used as a transfer device for linearly moving the device from the atmosphere side to the vacuum side.
In the existing technology shown in FIGS. 1 and 2, the moving flange 2 is applied with a large force due to the differential pressure between the atmosphere and the vacuum. For example, a pressure difference of 0.77 kN is generated in a flange having a diameter of 100 mm. For this reason, in order to raise and lower the moving flange, a large driving torque is required for the chain 9, and the chain 9 is often deformed (elongated). When the chain 9 is deformed, a drive timing shift occurs between the feed screws. FIG. 2 is a horizontal sectional view of FIG. When the chain 9 is slack, when the chain is rotated counterclockwise, the feed screw 4a first rotates, and then the drive torque is transmitted from the sprocket 6a attached to the feed screw 4a to the chain 9 to the sprocket 6b. The screw 4b rotates, and finally, the driving torque is transmitted from the sprocket 6b attached to the feed screw 4b to the chain 9 to the sprocket 6c, and the feed screw 4c rotates. When the rotation is reversed, the feed screws 4a, 4c and 4b are driven in this order. Therefore, when the chain 9 is loose, the moving flange is shaken due to the drive screw driving deviation depending on the rotation direction of the chain 9. Although the tensioner 8 is incorporated in order to eliminate the looseness of the chain 9, continuous deformation of the chain 9 during use cannot always be removed. In addition, there is a large backlash between the chain 9 and the sprockets 6a, 6b, 6c. Therefore, highly accurate linear movement is impossible.

  In order to solve the above-described problems, in the present invention, accurate and highly accurate linear guidance is possible by driving the feed screws attached at equal intervals while synchronizing them. In order to make this possible, it is possible to solve the problem by connecting the motors to the individual feed screws and driving them while synchronizing them, instead of connecting the feed screws with a chain and simultaneously driving them by one motor.

That is, the linear drive introducer of the present invention is guided by a plurality of linear guides at equal intervals around the bellows, a bellows that can be stretched and held in a vacuum, a flange that is attached to the stretchable end of the bellows, The linear drive introducer includes a plurality of moving plates that are individually driven by a plurality of feed screws at equal intervals around the bellows, and a plurality of motors that individually rotate and drive the plurality of feed screws. The flanges are attached to the plurality of moving plates, and the plurality of moving screws are individually rotationally driven by the plurality of motors, whereby the plurality of moving plates are individually linearly driven to advance and retract the flanges. It is characterized by.
In the linear drive introducer according to the present invention, the plurality of moving plates are driven synchronously to advance and retract the flange, and the plurality of moving plates are driven independently. The inclination of the flange can be freely controlled.
Further, the present invention is characterized in that, in the linear drive introducer, the flange is mounted on the plurality of moving plates via balls and is supported in a tiltable manner.

In the linear drive introducer of the present invention, the position resolution of the lead screw depends on the lead screw lead and motor resolution. For example, when a lead screw with a lead of 2 mm and a stepping motor with a resolution of 100,000 pulses / rotation are used, the position resolution of the feed screw is 20 nm. Actually, in consideration of the rotation accuracy of the stepping motor, the position resolution of the lead screw is ± 70 nm. However, if accurate linear guidance becomes possible, an optical high-accuracy position reading device having a spatial resolution of 10 nm or less can be incorporated into the linear drive introducer. By performing position control of the position information of the optical high-accuracy position reading device to the motor, the rotation of the motor can be controlled with the theoretical resolution (20 nm) of the feed screw. The position control of the moving flange can be performed by driving each motor in synchronization.
By connecting the nut of the feed screw and the moving flange independently and driving the feed screw independently, the inclination of the moving flange can be adjusted. The inclination control of the moving flange can be performed by driving each motor independently. For example, in the case of a lead screw with a lead of 2 mm, a stepping motor with a resolution of 100,000 pulses / rotation, and a pitch circle diameter of a 250 mm feed screw, the angular resolution of the tilt angle is 0.000000045 °.

It is a general view of the linear drive introducer by the existing technology. It is a horizontal sectional view of the linear drive introducer by the existing technology. 1 is an overall view of a linear drive introducer according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the linear drive introducer which concerns on one Embodiment of this invention. It is a figure explaining the drive principle of the stepping motor by the input signal which concerns on this invention.

3 and 4 (longitudinal sectional view of FIG. 3) are examples of the linear drive introducer according to the present invention.
A bellows 23 that can be expanded and contracted and can be held in vacuum is attached to the flange 21. A flange 22 is attached to the other end of the bellows 23 so as to be movable in the expansion and contraction direction of the bellows 23. The flange 21 is provided with linear guides 25a, 25b, 25c (reference numeral 25b is not shown) and its support posts 26a, 26b, 26c (reference numeral 26b is not shown) at equal intervals concentrically around the bellows 23. It is attached. A fixed plate 30 is attached to the other end of the linear guides 25a, 25b, 25c. Further, synchronization can be achieved by driving the tapping motors 32a, 32b, 32c between the flange 21 and the fixed plate 30 with the bellows 23 as the center.
31a, 31b and 31c are stepping motor mounting plates, and 33a, 33b and 33c are couplings for connecting the stepping motor and the feed screw. Reference numeral 40 denotes a feed screw fixed side bearing, reference numeral 41 denotes a feed screw support side bearing, and reference numerals 28a, 28b and 28c (reference numeral 28b not shown) denote housings of the feed screw fixed side bearing.
In order to realize the high position resolution of the linear drive introducer, it is necessary to use a small lead screw and a high resolution stepping motor. For example, when a lead screw with a lead of 2 mm and a stepping motor with a resolution of 100,000 pulses / rotation are used, the calculated position resolution of the linear drive introducer is 20 nm / pulse. Considering the lost motion of the stepping motor (0.025 ° or less (± 0.2 N · m)), the actual position accuracy of the stepping motor is about ± 70 nm. By incorporating a high-resolution position reader having a spatial resolution of 10 nm or less into the linear drive introducer, position control can be performed with a resolution comparable to the calculated position resolution of the stepping motor.
When the flange 21 is attached to a vacuum device, the same vacuum is applied before and after the flange 21 and no differential pressure is generated. On the other hand, before and after the flange 22, there is a vacuum side and an atmosphere side, and the flange 22 applies a large pulling force to the vacuum apparatus side due to the differential pressure. Using the pulling force applied to the flange 22, the moving plates 27 a, 27 b, 27 c and the flange 22 are not securely fastened with bolts or the like, and the flange 22 is placed on the moving plates 27 a, 27 b, 27 c via the balls 29. Has a structure that can be tilted freely.

  4 is a longitudinal sectional view of FIG. The flange 22 has a structure that rides on the moving plate 27 via a ball 29. The moving plates are individually structured, and the inclination of the flange 22 can be freely controlled by individually controlling the position of the moving plate by each stepping motor. In this case, it is necessary to control the stepping motor independently.

FIG. 5 shows a driving method of the stepping motor by the input signal from the pulse generator. By synchronously driving each stepping motor with a specific input signal via a booster, the apparatus functions as a linear transfer machine. In FIG. 5, a specific input signal # 1 is input to the drivers A, B, and C from the Z terminal side via a booster to drive the stepping motors A, B, and C in synchronization.
On the other hand, when the stepping motor is driven by an input signal independent from the stepping motor, the apparatus can control the inclination. In FIG. 5, the input signal # 1, the input signal # 2, and the input signal # 3 are input from the Tilt terminal side to the drivers A, B, and C, respectively, and the stepping motors A, B, and C are driven independently.

In the above description, the stepping motor is used. However, the present invention is not limited to the stepping motor, and can be realized by other motors.
Further, by combining an XY stage with a linear drive introducer, it functions as a three-dimensional transfer device in the XYZ axial directions.

  The linear drive introducer of the present invention is a linear drive introducer that introduces a highly accurate linear motion from the atmosphere side to the vacuum side, and further has a function of allowing an inclination angle, and an optical element or material in a vacuum. It is expected to be effective for equipment that requires high-precision position control and tilt control.

1, 2, 21, 22 Flange 3,23 Bellows 4a, 4b, 4c Feed screw 5a, 5b, 5c Linear guide 6a, 6b, 6c Sprocket 7a, 7b, 7c Idler 8 Tensioner 9 Chain 10 Wheel gear 11 Worm gear 12 Motor 13 Couplings 24a, 24b, 24c Feed screws 25a, 25b, 25c Linear guides 26a, 26b, 26c Posts 27a, 27b, 27c Moving plates 28a, 28b, 28c Housing 29 Ball 30 Fixed plates 32a, 32b, 32c Stepping motors 33a, 33b 33c Coupling 40 Feed screw fixed side bearing 41 Feed screw support side bearing
(Note that reference numerals 6a, 24b, 25b, 26b, and 28b are not shown)

Claims (3)

Bellows that can be stretched and held in vacuum,
A flange attached to the expansion end of the bellows;
A plurality of moving plates guided by a plurality of linear guides at equal intervals around the bellows and individually driven by a plurality of feed screws at equal intervals around the bellows;
A linear drive introducer comprising a plurality of motors for individually rotating the plurality of feed screws,
The flanges are attached to the plurality of moving plates, and the plurality of moving screws are individually driven to rotate by the plurality of motors, whereby the plurality of moving plates are individually linearly driven to advance and retract the flanges. A linear drive introducer.   The flanges are moved forward and backward by driving the plurality of moving plates synchronously, and the inclination of the flanges can be freely controlled by driving the plurality of moving plates independently. The linear drive introducer according to claim 1, wherein   The linear drive introducer according to claim 2, wherein the flange is attached by supporting the plurality of moving plates via balls and is tiltably supported.

Images