JPH07334245A - Ultra-precision feeding device, xy table using the same and table transferring device - Google Patents

Abstract

PURPOSE:To provide a ultra-precision feeding device, an XY table using the device and a table transferring device capable of ensuring an absolute position. CONSTITUTION:This device is provided with a feeding amount detecting means S1 for detecting a feeding amount, information detecting means S2 and S3 provided inside the device so as to successively detect any one of information concerning a shape error E for each feeding position, information concerning thermal deformation caused by the temperature distribution of the device and information concerning deformation caused by external force F at least, a storage means 30 for previously storing the relation between the detected information of the information detecting means S2 and S3 and a positioning error DELTAand the relation between the shape error E at each other part of the device and the positioning error DELTA as knowledge, and a computer C for controlling an actuator A by calculating a corrected controlled variable based on the detected information successively detected by the feeding amount detecting means S1 and the information detecting means S2 and S3 and the stored information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision positioning feeder used in, for example, machine tools, robots, semiconductor manufacturing equipment, various inspection equipment, etc., and more particularly to an internal monitor feeding equipment and an XY table using the same. And a table transfer device.

[0002]

2. Description of the Related Art In recent years, there is an increasing demand for higher precision in fine processing, as represented by semiconductor technology. Since the development of NC (Numerical Control), the machining accuracy has improved dramatically due to the high rigidity and position control of each part of the machine.

In such position control, since the table position and the tool position are all determined by the product shape, the feed amount and procedure of the machining table and the tool are determined in advance, and the drive mechanism side,
That is, in most cases, the position on the sending side is controlled while being monitored by a rotary encoder or the like.

[0004]

However, what monitors the position of the sending side in this way merely estimates the position of the actually sent tool or table, and the actual position of the tool or table. The location information of does not come out.

That is, at the processing site, as shown in FIG. 13, all the components of the machine are deformed by the force N and the heat H, and even if the position of the sending side is monitored, the force N and the heat H are generated. The actual feed position changes from the target position due to the influence of deformation due to.

In a normal machine, high rigidity is used to counter the deformation caused by force, and a constant temperature environment is used to counter the heat deformation so that the machine is not affected by the deformation.
All of these are only passive measures and have limitations.

Conventionally, the position on the sending side is actually detected by a linear scale or the like to perform positioning control. However, in an actual machining site, the linear scale itself is deformed by the influence of heat or force. It does not serve as an absolute standard. Therefore, it is conceivable to monitor the feed position from the outside of the device, but it is difficult to obtain an absolute standard due to the problem of the external environment where the sensor is placed.

Therefore, in order to perform the positioning with higher accuracy, it is necessary to incorporate the idea of "intelligence of processing".

Intelligent processing means that the physical phenomenon occurring at the processing site is taken in as information by Sanse, input to a model prepared in advance, the output from that is compared with the target value determined from the design, and the The actuator is moved according to the difference, and the phenomenon itself that occurs during machining is changed in real time to perform the intended machining.

From this point of view, various attempts have been made at present to manufacture concrete machine tools in order to realize intelligent processing, and the present invention relates to an intelligent feeding device.

Further, the feeding device has the following problem in addition to the above-mentioned problem of positioning error.

That is, a piezoelectric element has been conventionally known as an actuator that realizes a minute resolution on the order of angstroms, and is used in various ultra-precision machines such as a scanning tunneling microscope and an electron beam drawing apparatus. But,
This is because the stroke is 300 [n even if the lever mechanism is used together.
The disadvantage is that it is as small as [m].

On the other hand, as an actuator capable of realizing a large stroke of about 100 mm, a mechanism utilizing a ball screw is widely used in machine tools and automatic transfer devices. However, this ball screw (for example, diameter 4
[Mm]) has a small rigidity of about 10 [N / μm], and is deformed by an external force, and the positioning error in the feed direction due to the processing accuracy when grinding and finishing this is as large as 8 [μm]. That is a drawback.

Thermal expansion often occurs in the structure for fixing these piezoelectric elements and ball screws, and the resolution of the actuator is 0.1 [μm] in a machine tool, for example.
Even if it is small, the distance between the tool and the work piece is 1 from the set value.
It is known that the positioning accuracy deteriorates due to a large deviation from 0 [μm] or more.

The present invention has been made to solve the above-mentioned problems of the prior art, and the purpose thereof is to:
Incorporating the concept of intelligent processing, a detection means for sequentially detecting various factors such as thermal deformation, force deformation, and component shape error that cause positioning error is provided, and the absolute position is determined by comprehensive control. An object of the present invention is to provide an ultra-precision feeding device that can be guaranteed, an XY table and a table transfer device using the same.

It is another object of the present invention to provide an ultra-precision feed device capable of realizing a large stroke, high resolution and precise positioning, and arbitrary rigidity, an XY table and a table transfer device using the same.

[0017]

In order to achieve the above object, according to the present invention, a driving means, a feed amount detecting means for detecting a feed amount, information on a shape error for each feed position, and an apparatus. Information regarding the thermal deformation due to the temperature distribution and the information detecting means provided inside the device for sequentially detecting at least one of the information regarding the deformation due to the external force, the information detected by the information detecting means and the positioning error. A storage unit that stores the relationship and the relationship between the shape error and the positioning error of each part of the device as knowledge in advance, the detection information sequentially detected by the feed amount detection unit and the information detection unit, and the correction control amount based on the stored information. And a control means for driving the driving means in accordance with the above-mentioned requirement.

The control means is characterized in that the relationship between the positioning error, the feed amount detecting means and the information detecting means, and the correction control amount of the driving means is learned in advance.

The learning is characterized by being performed by a distance detecting means which measures the distance from the reference position.

The drive means is composed of an actuator group in which a coarse movement mechanism and a fine movement mechanism are arranged in series, and a positioning error is corrected by the fine movement mechanism.

The force sensor is arranged in a path through which an external force inside the device is transmitted.

A deformation sensor for detecting thermal deformation is characterized by detecting axial expansion / contraction of a portion which affects a positioning error.

The coarse movement mechanism is a screw feed mechanism such as a ball screw.

The fine movement mechanism is a command for a piezoelectric element, an electrostrictive element, an actuator that expands and contracts using thermal expansion, an actuator that expands and contracts using fluid pressure, an actuator that uses a voice coil, and an actuator that uses a magnetostrictive element. It is characterized in that it is provided with a minute displacement means that expands and contracts in proportion to the value.

The fine movement mechanism is provided with a minute displacement means and an elastic member which is deformable in the displacement direction of the minute displacement means and is rigid in the direction orthogonal to the displacement direction.

The fine movement mechanism is characterized in that a deformation sensor is arranged in parallel with the fine displacement means, and the fine displacement means is controlled by feedback control.

Further, the XY table of the present invention comprises a base and
A first table movably arranged on the base in the X-axis direction via a linear motion guide mechanism, and a Y-axis orthogonal to the X-axis on the first table via the linear motion guide mechanism. A table that is movable in the direction, a feed mechanism that is provided between the base and the first table and that feeds the first table in the X-axis direction, and a table that is provided between the first table and the second table. A feed mechanism for feeding the second table in the Y-axis direction, and it is possible to correct a planar positioning error in the X-axis direction and the Y-axis direction by using the above-mentioned ultra-precision feed device as the X-, Y-axis direction feed mechanism. It is characterized by having done.

Further, the warp amount detecting means for sequentially detecting the warp amount in the Z-axis direction orthogonal to the X-axis and Y-axis of the base, the distance between the base and the first table, the first table and the second table. Distance detecting means for detecting a distance in the Z-axis direction between
In addition to the above, the linear movement guide device is provided with a minute displacement means for generating displacement in the Z-axis direction, the detection information of the warp amount detection means and the distance detection means, and the Z-axis direction for each feed position in the XY-axis direction. The relationship between the positioning errors is stored as knowledge in advance, and a correction control amount in the Z-axis direction is obtained based on the detection information and the stored information sequentially detected by the warp amount detection means and the distance detection means, and a minute amount in the Z-axis direction is obtained. It is characterized in that a control means for controlling the displacement means is provided so that a three-dimensional positioning error in the X-, Y-, and Z-axis directions can be corrected.

The table transfer device of the present invention comprises a base, a table movably disposed on the base via a linear motion guide mechanism, and a table provided between the base and the table. And a feed mechanism for driving, using the ultra-precision feeding device as a feed mechanism, while, the warp amount detection means for sequentially detecting the warp amount in the height direction orthogonal to the feed direction of the base, and the base. Distance detecting means for detecting the distance between the tables, and minute displacement generating means for generating displacement in the height direction orthogonal to the feed direction in the linear motion guiding device, and the warping amount detecting means and the distance. The relationship between the detection information of the detection means and the positioning error in the height direction for each feed position of the table is stored in advance as knowledge, and based on the detection information and the storage information sequentially detected by the warp amount detection means and the distance detection means. There characterized in that the provided control means for driving the micro-displacement generation means seeking compensation control amount in the height direction.

[0030]

According to the present invention, the relationship between the detection information of the information detecting means for detecting the error factor information such as external force and heat and the positioning error and the relationship between the shape error and the positioning error of other parts of the apparatus are stored in advance as knowledge by learning. deep.

During the feeding operation, the feeding position is successively detected by the feeding amount detecting means provided in the apparatus itself.
Further, by the information detecting means provided in the device itself, the positioning error caused by the shape error for each feed position,
At least one of a positioning error due to thermal deformation due to the temperature distribution of the device and a positioning error due to deformation due to an external force is sequentially detected.

Of course, the most effective way of detecting the error factor is to detect all of the shape error at each feed position, thermal deformation, and external force, but it is also effective to eliminate any one error. Various selections can be made according to accuracy requirements.

In the control means, the correction control amount is obtained based on the detected information and the stored information, and the driving means is controlled to correct the positioning error.

If the drive means is constituted by an actuator group in which a coarse movement mechanism and a fine movement mechanism are arranged in series, a large stroke can be realized by the coarse movement mechanism and precise positioning and high resolution can be realized by the fine movement mechanism.

Further, the XY table of the present invention can be subjected to absolute planar positioning in the X and Y axis directions by the internal monitor type feeding device.

Further, by detecting the warp amount of the base, the distance between the base and the first table, and the distance between the first table and the second table, it is possible to detect the flat feed position in each of the XY axis directions. The positioning error in the Z-axis direction can be detected, and the positioning error in the Z-axis direction can be corrected by the minute displacement means in the Z-axis direction provided in the linear motion guide mechanism, thereby enabling three-dimensional absolute positioning.

The table transfer device of the present invention can detect the positioning error in the height direction at each feed position of the table by detecting the warp amount of the base and the distance between the base and the table. By correcting the positioning error in the direction by the minute displacement means in the height direction provided in the linear motion guide mechanism, the three-dimensional absolute positioning becomes possible.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

1 to 3 show a first embodiment of an internal monitor type ultra-precision feeding device of the present invention.

FIG. 1 shows a conceptual configuration.
Shows a more concrete view. Of these, FIG. 2B is merely a conceptual view of FIG. 2A, and the configuration is exactly the same.

As shown in FIG. 1 (B), this feeding device monitors the positioning error Δ due to the influence of the shape error E, external force F, and heat H of the device. S1, a force sensor S as information detecting means for detecting information on factors affecting the positioning error.
2. A sensor group such as a thermal deformation sensor S3 or a sensor (not shown) that detects information on a shape error for each feed position, the relationship between the detection information of these sensor groups and the positioning error Δ, and other shape errors E and positioning of each part of the apparatus This is a feeding device that realizes a desired function by a computer C that stores the relationship of the error Δ as knowledge in advance and determines the correction amount by the small displacement actuator A.

The first embodiment is an example in which only the shape error E and the positioning error caused by the deformation by the force F are corrected by the internal monitor method.

The internal monitor system is a sensor attached to oneself, and is to know one's posture in process during work.

The feeding device 1 is shown in FIG. 1 (A), FIG. 2 and FIG.
As shown in FIG. 2, the coarse movement mechanism 2 and the fine movement mechanism 3 arranged in series with the coarse movement mechanism 2 are provided.
A large stroke is ensured by, and the positioning error Δ with respect to the target position O is compensated by the fine movement mechanism 3 as shown in FIG.

The coarse movement mechanism 2 is, as shown in FIG.
A ball screw shaft 4, a ball nut 5 screwed to the ball screw shaft 4, a large number of balls 6 interposed between the ball screw shaft 4 and the ball nut 5, and a motor M for rotationally driving the ball screw shaft 4. It consists of and. Ball screw shaft 4
Is rotatably supported by a bearing stand 8 standing on a base stand 7 via a bearing 9 such as an angular contact ball bearing. The motor M is supported by a motor support wall 10 provided on the base 7, and the drive shaft 11 of the motor M and the ball screw shaft 4 are operatively connected via a joint member 12.

Further, as shown in FIG. 3, the ball nut 5 is linearly guided in the axial direction of the ball screw shaft 4 via a linear motion guide mechanism 13 which supports the left and right side surfaces thereof. The linear motion guide mechanism 13 includes a linear fixed rail 14 fixed to the base 7, a movable rail 15 fixed to the ball nut 5, and a rolling rail interposed between the fixed rail 14 and the movable rail 15. It is composed of rolling elements such as balls (not shown) mounted.

The fine movement mechanism 3 comprises a fine displacement actuator 16 such as a piezoelectric element, and a displacement sensor 17 provided in parallel with the fine displacement actuator 16 for detecting a fine displacement. The displacement sensor 17 includes a parallel plate elastic member 18 provided in parallel with the micro displacement actuator 16, and a strain gauge 19 attached to the elastic member 18.
Composed of. As shown in an exaggerated manner in FIG. 2D, the elastic member 18 is deformable in the axial direction and is rigid in the directions other than the direction orthogonal to the axial direction. The strain gauge 19 detects the displacement amount of the small displacement actuator 16 and feeds it back to the fine movement control circuit 31 to accurately control the correction amount.

That is, the elastic member 18 connects the fixed portion 20 fixed to the ball nut 5, the movable portion 21 on the free end side provided apart from the fixed portion 20, and the fixed portion 20 and the movable portion 21. The strain gauge 19 is formed of a parallel plate-shaped spring portion 22 extending in a direction orthogonal to the axis, and the strain gauge 19 is attached to a base position of the fixed portion 20 and the movable portion 21 of the spring portion 22. In addition, the minute displacement actuator 16
Is mounted between the movable portion 21 and the fixed portion 20 of the elastic member 18.

As the displacement sensor of the fine movement mechanism 3, in addition to the one using the parallel plate structure as in the above embodiment, a resistance type sensor such as a strain gauge, a piezoelectric element or an electrostrictive element is used to detect the displacement as a voltage change. Various well-known sensors capable of detecting minute displacements, such as a voltage type sensor, an electromagnetic induction type sensor such as a differential transformer or an eddy current sensor, a capacitance type sensor, an optical interference type sensor using an optical fiber, etc. are used. be able to.

As the small displacement actuator 16, a piezoelectric element, an electrostrictive element, an actuator that expands and contracts by using thermal expansion, an actuator that expands and contracts by using fluid pressure, an actuator that uses a voice coil, and a magnetostrictive element are used. It is possible to use various actuators that expand and contract in proportion to the command value of the actuators.

The motor M is provided with an encoder 23 as a feed amount detecting means for detecting the feed position. As the encoder 23, a rotary encoder is used in the illustrated example. The rotary encoder may detect the rotation amount of the motor M or may detect the rotation amount of the ball screw shaft 4. A linear encoder may be used instead of the rotary encoder.

When a linear encoder is used, the feed position of the ball nut 5 or the driven part 24 may be read, or the moving amount of the moving rail 15 with respect to the fixed rail 14 of the linear motion guide device 13 may be detected. You may

On the other hand, a force sensor 25 is provided on the path through which the external force acting on the device propagates inside the device. In this embodiment, the force sensor 25 is provided in series between the movable portion 21 of the fine movement mechanism 3 and the driven portion 24 to which the fed member is attached.

As exaggeratedly shown in FIG. 2C, the force sensor 25 also includes an elastic member 26 having a parallel flat plate structure which is elastically deformable in the axial direction and rigid in the direction orthogonal to the axis, and this elastic member. And a strain gauge 27 for detecting the strain amount of the elastic member 26, and detects the axial load from the detected value of the strain amount of the elastic member 26.

Here, the elastic member 2 constituting the fine movement mechanism 3
6. The block up to the force sensor 25 and the driven part 24 is formed by one block body.

The path through which the force passes reaches the base 7 through the driven part 24, the force sensor 25, the minute actuator 16 and the elastic member 26, the ball nut 5, the ball 6, the ball screw shaft 4, the bearing 9 and the bearing base 8. It is a route. Force sensor 25
Is not between the driven part 24 and the fine movement mechanism 3, but between the fine movement mechanism 3 and the ball nut 5, the ball nut 5 itself, the bearing 9 and the bearing stand 8, the bearing stand 8 itself, the bearing stand 8 and the base stand. It can be provided at various positions as required, such as between 7 and the like.

FIG. 1A shows the control structure of this feeding device.

The control system includes a coarse movement control system of the coarse movement mechanism 2 and a fine movement control system of the fine movement mechanism 3.

In the coarse motion control system, the feed amount is input as a command value to the coarse motion control circuit 28, a drive signal for the motor M is output based on this command value, and the motor M is transmitted via the drive circuit 29.
Is rotated by a predetermined amount. This makes the ball screw shaft 4
Is rotated by a predetermined amount, the rotational movement of the ball screw shaft 4 is converted into the linear movement of the ball nut 5, and the ball screw shaft 4 is moved by a predetermined amount in the axial direction.

On the other hand, the fine movement control system shows the relationship between the pitch error and the positioning error for each feed position of the ball screw shaft 4 as the shape error of the device for each feed position, and the relationship between the detection information of the force sensor 25 and the positioning error. Learned and stored in the memory 30.

The shape error of the device that affects the positioning error of the driven part 24 is considered to be a factor in which the pitch error of the ball screw shaft 4 is large. Of course, the shape error of each part of the device that affects the positioning error is appropriately selected depending on the other device configuration. This pitch error is detected in advance and stored in the memory 30 as knowledge.

Then, the information of the external force F detected by the force sensor 25 and the feed position information from the encoder 23 are input to the fine movement control unit 31, and in the fine movement control unit 31, the external force information and the feed position information and the memory. The correction control amount of the fine movement mechanism 3 is calculated from the relationship with the positioning error stored in 30, and the correction movement amount of the fine movement mechanism 3 is controlled. This small displacement actuator 16 of this fine movement mechanism 3
Is expanded and contracted by a predetermined amount via the drive circuit 31a based on the correction control signal from the fine movement control circuit 31.

Here, an experimental example is shown.

The ball screw shaft has a diameter of 4 mm and a lead 1
In [mm], a structure was used in which two nuts were preloaded with a central leaf spring to eliminate backlash. Positioning reproducibility is 100 [nm] or less and always 3 [N ・ m]
m] friction torque is generated and heat is generated.

As the small displacement actuator 16, 5 ×
A piezoelectric element having a laminated structure with dimensions of 5 × 9 [mm] was used.
Generally, the relationship between the voltage applied to the piezoelectric element and the amount of expansion / contraction at that time is as large as about 5% both in hysteresis and non-linearity. Therefore, a parallel flat plate displacement sensor is arranged in parallel with the piezoelectric element, and a feedback circuit, that is, a computer A circuit for applying a voltage to the small displacement actuator 16 was designed so that the set value of the signal voltage to be supported is equal to the measured value output from the displacement sensor 18.

When this is used, hysteresis and non-linearity are reduced, and the reproducibility of the expansion / contraction amount of the piezoelectric element is 5 [nm].
Becomes smaller.

The force sensor 25 is the small displacement actuator 1
It is arranged in series with 6. Due to the elastic member 26 having the parallel plate structure and the strain gauge 27, the hysteresis / non-linearity is as small as 2% or less. The rated load of the force sensor 25 is 5N,
The rigidity is 1.4 [N / μm].

Further, the positioning error was measured by the laser length measuring device 32 as the distance detecting means for measuring the distance from the reference position. The laser length measuring device 32 is used for learning and evaluation of the feeding device, and does not control the minute displacement actuator 16 in-process using this information. However, the feed pitch error of the ball screw as the shape error of the device is detected and stored in the memory, and in that sense, it constitutes the information detecting means of the present invention.
This laser length measuring device may be provided outside the device or inside the device.

The positioning error was measured without controlling the internal monitor method, and the result is shown in FIG.

FIG. 4A shows a state where no external force is applied.
The difference between the position measured by the laser length-measuring device 32 and the target position O that was desired to be sent by the operation when intermittently sending a total of 5 [mm] every 1.389 [μm] is shown. 1 for pitch
There is an error of ± 3 [μm] due to machining as the cycle, and in the ball nut 5, an impact value of 0.3 [μm] is generated when the balls are inserted into the nut groove from the retainer. It takes 45 minutes to feed 5 [mm], which means that thermal expansion of 0.5 [μm] occurs.

FIG. 4 (B) shows the relationship between the magnitude of the external force F and the positioning error (change amount) Δ that varies when the external force F is applied in the feed direction while the motor M is stopped. Shows. The rigidity of 1.4 [μm / N] is almost equal to the rigidity of the force sensor 25.

As shown in FIG. 1 (B), the computer carried out preliminary experiments in advance to find the positioning error Δ and the force sensor 2
It is necessary to learn the relationship between the 5 output values and the input value of the small displacement actuator 16. The relationship between the positioning error Δ and the output signal of the encoder 23 is shown in FIG. 4 (A), and the relationship with the output signal of the force sensor 25 is shown in FIG. 4 (C). The relationship is shown in Figure 5 below.
It shows with (A).

As shown in FIGS. 4 (B) and 5 (A), both the force sensor 25 and the fine movement mechanism 5 use a parallel plate structure, so that the linearity is good.

Next, using the relationship stored in the computer, the positioning error is corrected while monitoring the input signal. The result of correcting the shape error is shown in FIG. 5 (B), and the result of correcting the external force is shown in FIG. 5 (C). FIG. 4A without correction control,
When compared with 4 (B), the positioning error due to the processing accuracy is small from ± 3 [μm] to ± 0.3 [μm],
It can be seen that the rigidity is large from 1.4 [μm / N] to 20 [μm / N], and changes by an order of magnitude.

The positioning error when no external force was applied, that is, vibration due to disturbance was ± 0.05 [μm]. Given this and the thermal effects mentioned above, it is clear that the above correction is further improved.

6 and 7 show a second embodiment of the present invention.

The second embodiment is an example in which a thermal deformation sensor 33 is added to the feeding device of the first embodiment, and the same components as those of the first embodiment are designated by the same reference numerals. The description is omitted.

That is, as shown in FIG. 6, as the error factor detecting means for detecting the positioning error due to the deformation due to the external force and the positioning error due to the thermal deformation, the same force sensor 25 as in the first embodiment is used. In addition to the above, a thermal deformation sensor 33 is provided, and as a knowledge to be learned and stored, a positioning error caused by thermal deformation is added, and information about a positioning error factor that is sequentially obtained from the force sensor 25 and the thermal deformation sensor 33 is held as knowledge. The correction control amount of the fine movement mechanism 3 is obtained based on the information of the positioning error.

In the illustrated example, the base 7 is selected as a representative portion that affects the positioning error caused by thermal deformation, and the thermal deformation sensor 33 detects the amount of thermal deformation of the base 7. A bearing base 8 is fixed to the base 7,
When the base 7 expands and contracts, the position of the ball screw shaft 4 also changes, which causes a positioning error, and is affected by the heat generation of the motor M and the temperature change of the installation environment where the base 7 is fixed.

The thermal deformation sensor 33 has a reference member 34 of substantially the same length as the base 7 arranged in parallel with the ball screw shaft 4.
And a displacement sensor 35 that detects the relative displacement of the reference member 34 and the base 7 in the axial direction. That is, one end of the reference member 34 is fixed to one end of the base 7, and the relative displacement amount between the other end of the reference member 34 and the other end of the base 7 is detected by the displacement sensor 35. By this, the amount of thermal deformation of the base 7 is detected, and the positioning error due to the thermal deformation is obtained.

As the reference member 34, it is desirable to use a material having a very small coefficient of linear expansion and a negligible amount of thermal expansion, for example, Super Invar, but if the member has a known coefficient of thermal expansion, its relative displacement amount. The temperature change can be known by.

As the displacement sensor 35, as shown in FIG. 7B, an elastic member 36 having a parallel plate structure which is deformable in the axial direction and is rigid in the direction orthogonal to the axial direction, and the elastic member 36. It is composed of a strain gauge 37 to be attached. The elastic member 36 includes a base-side fixing portion 38 fixed to the base 7 and a reference-member-side fixing portion 3 fixed to the reference member 36.
9 and a parallel plate-shaped spring portion 40 extending in a direction orthogonal to the axial direction connecting between the base-side fixing portion 38 and the reference member-side fixing portion 39, and the strain gauge 37 includes the spring portion 40.
It is attached to the base side and the base member side fixing portions 38 and 39 at the base positions.

As the displacement sensor 35, a resistance type sensor such as a strain gauge is used without using the elastic member 36, a voltage type sensor for detecting displacement as a voltage change using a piezoelectric element or an electrostrictive element, a differential transformer or a vortex. Various known sensors capable of detecting a minute displacement, such as an electromagnetic induction type sensor such as a current sensor, a capacitance type sensor, a light interference type sensor using an optical fiber or the like, can be used.

FIG. 8 shows the result of an experiment on thermal deformation under the same conditions as in the first embodiment.

FIG. 8A shows the relationship between the output of the thermal deformation sensor 33 and the positioning error Δ. FIG. 8B shows a result obtained by storing the data as knowledge and correcting the positioning error amount corresponding to the output of the thermal deformation sensor 33 by the micro displacement actuator 16. In this way, the influence of thermal deformation can be eliminated.

In this embodiment, the thermal deformation sensor 33 is provided on the side surface of the base 7. However, in the case of the ball screw shaft 4, frictional heat is generated between the ball nut 5 and the ball screw shaft 4, so that a thermal expansion positioning error occurs. It is effective to directly detect the thermal expansion of the ball screw shaft 4 in the axial direction as the part that directly affects the temperature.

In this case, for example, as shown in FIG. 9 (A), the ball screw shaft 4 has a hollow structure, and the hollow hole 4
1, the reference member 34 is inserted, one end of the reference member 34 is fixed to one end of the ball screw shaft 4, and the relative displacement between the free end of the reference member 34 and the free end of the ball screw shaft 4 is detected by the displacement sensor 35. You can do it like this.

As for the installation position of the thermal deformation sensor 33, as shown in FIGS. 9B and 9C, the ball nut 5 is installed.
May be provided on the track rail 42 of the linear motion guide mechanism for linearly guiding. The illustrated example is an example of a linear motion guide device in which a moving block 44 is mounted on a track rail 42 via rolling elements 43 such as balls so as to be movable in a linear direction. A hollow hole 45 penetrating the track rail 42 in the axial direction.
The reference member 34 may be inserted similarly to the ball screw shaft 4, and the relative displacement between the track rail 42 and the free end of the reference member 34 may be detected by the displacement sensor 35.

When the linear encoder is provided, it may be attached to the base body of the linear encoder to detect the thermal expansion amount of the linear encoder itself. That is, since the feed position is detected by the linear encoder, the correct position of the positioning error caused by the temperature change of the feed position can be determined if the thermal deformation amount of the linear encoder is known.

Further, in the above-described embodiment, the thermal deformation amount is directly detected as the information on the thermal deformation, but the thermal deformation amount corresponding to the temperature distribution is held as knowledge, and the thermal deformation is detected by detecting the temperature distribution. You may make it detect.

FIG. 10 shows a third embodiment of the present invention.

Like the second embodiment, the third embodiment is configured to eliminate the factors of thermal deformation, but the difference from the first and second embodiments is that the ball screw shaft 4 has Both ends are supported via bearings 9, 9 and a thermal deformation sensor 33 is provided between both bearing bases 8, 8. In this case, in the strict sense, the thermal deformation sensor 33 detects not only thermal deformation but also deformation due to force, but since deformation due to force is smaller than deformation due to heat, it represents thermal deformation. Can be considered.

Since the other structure and operation are the same as those of the second embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

In each of the above-mentioned embodiments, the uniaxial feed device has been described as an example.
You can also configure the table.

FIG. 11 shows an example of the XY table.

That is, the first table 52 sent in the X-axis direction is arranged on the base 51, and the first table 52 is further placed.
The second table 53 to be fed in the Y-axis direction orthogonal to the X-axis is arranged on the above.

The first table 52 has a linear motion guide mechanism 54.
The second table 53 is movably supported in the X-axis direction with respect to the base 51 via the, and the second table 53 is movably supported in the Y-axis direction by the first table 52 via the linear motion guide mechanism 55.

A feed mechanism 56 for feeding in the X-axis direction is provided between the base 51 and the first table 52, and a feed mechanism 56 for feeding in the Y-axis direction between the first table 52 and the second table 53. Mechanisms 57 are provided respectively.

The X-axis and Y-axis direction feed devices 56 and 57 have the same structure as that of the first to third embodiments, and the ball screw shaft 58 rotated by the motor M and the ball screw shaft 58. A coarse movement mechanism 60 composed of a ball nut 59 screwed through a ball to which a preload is applied,
The fine movement mechanism 61 includes a fine displacement actuator such as a piezoelectric element.

Then, the XY-axis feed mechanism 56,
The second table can be positioned in the XY directions by 57.

In this embodiment, furthermore, a minute displacement actuator 62 is provided on the moving block 54, 55 of the linear motion guide mechanism so that displacement in the Z-axis direction can be corrected and absolute positioning can be performed three-dimensionally. Is.

As shown in FIGS. 12B and 12C, the linear motion guide mechanisms 54 and 55 are movably supported by a track rail 63 and rolling balls 64 such as balls on the track rail 63. The moving block 65 is provided with the minute displacement generating actuator 62.

As shown in the figure, the micro displacement actuator 62 is constituted by combining an elastic member 66 having a flat plate structure which is deformable in the Z-axis direction and rigid in the other directions and a micro displacement actuator 67 such as a piezoelectric element. The strain gauge 68 attached to the elastic member 66 may feedback-control the displacement amount of the small displacement actuator 62,
Other piezoelectric elements, electrostrictive elements, or actuators that expand and contract using thermal expansion, actuators that expand and contract using fluid pressure, actuators that use voice coils, actuators that use magnetostrictive elements, etc. Various types of actuators that expand and contract can be used.

FIG. 12A schematically shows the control configuration of this XY table. The XY absolute position control system 72 is the same as the control system of the above-mentioned feeder, and X
The axial direction and the Y-axis direction are the same.

That is, the coarse movement mechanism 60 and the fine movement mechanism 61 are provided in both the XY-axis directions, and the coarse movement mechanism 60 has a coarse movement control circuit 69.
The fine movement mechanism 61 is controlled by the fine movement control circuit 70. In the control of the fine movement control circuit 70, the relationship between the shape error and the positioning error and the relationship between the positioning error caused by thermal deformation and force deformation are learned and stored in the memory 71 in advance.
The positioning error is determined from the detection information from the thermal deformation sensor 72 and the force sensor 73 that are sequentially input in-process and the stored information, the correction amount is obtained, and the fine movement mechanism 61 is controlled.

On the other hand, in the absolute position control system in the Z-axis direction, the small displacement actuator 62 provided in each moving block 65 of the linear motion guide mechanisms 54 and 55 is controlled by the Z-axis direction position control circuit 74. This Z-axis position control is based on X
The absolute position in the Z-axis direction at the feed position in the axis and Y-axis directions is detected, and the fine movement control section 70 in the XY-axis directions is detected.
Is controlled corresponding to.

In order to detect the displacement in the Z-axis direction, in this embodiment, two thermal deformation sensors 75 are attached to the side surface in the X-axis direction and the side surface in the Y-axis direction of the base 51 so as to be vertically spaced apart from each other. There is. The thermal deformation sensor 75 on the side surface of the base 51 is
In addition to the information for determining the positioning error of the feed position in the axis and Y-axis directions, the base 5
It is possible to know the vertical warp amount of 1 itself.

Further, the base 51 for each feed position in the XY axis directions
Between the base 51 and the first table 52 and between the first table 52 and the first table 52 in order to measure the distance in the Z-axis direction between the first table 52 and the second table 53. A distance meter 76 is provided between 52 and the second table 53 to sequentially detect the distance in the Z-axis direction. In FIG. 11, the distance meter between the base 51 and the first table 52 is not shown. The range finder 76 measures a straight line in each of the X-axis and Y-axis directions, and determines the displacement of the feed position in the X-axis direction in the Z-direction,
Since the displacement of the feed position in the Y-axis direction in the Z-direction is detected, the Z-position is detected at any feed position in the X-axis direction and the Y-axis direction.
Axial displacement can be detected, and absolute positioning in a three-dimensional space is possible.

That is, the warp amount of the base 51 is detected, the distance between the base 51 and the first table 52 is detected, the distance between the first table 52 and the second table 53 is detected, and they are calculated. Second table 5 by adding up
The positioning error in the Z-axis direction at the positioning portion in the XY directions on No. 3 is known, and the positioning error in the Z-axis direction is corrected by the micro displacement actuator 62.

In order to make this correction, the relationship between the detection information of the upper and lower two thermal deformation sensors and the Z-axis direction displacement caused by the warp is learned in advance and stored in the memory 77 as knowledge. The positioning error in the Z-axis direction may be obtained and corrected based on the information sequentially detected by the 75 and the distance meter 76. The value detected by the distance meter 76 is, after all, the deformation and shape error in the Z-axis direction of each component due to heat and force.

The above is the positioning of the XY table, but it is also applicable to the three-dimensional positioning of the uniaxial table transfer device that transfers the table to the base by the uniaxial feed device, and is exactly the same as the above XY table. Moreover, by measuring the warp of the base table and the distance between the base table and the table, it is possible to perform a three-dimensional absolute positioning.

Although not shown, only the base 51 and the first table 52 of the XY table of FIG.
A distance meter (not shown) may be provided between the first table 52 and the first table 52. The control configuration is exactly the same as the configuration shown in FIG.

[0113]

As described above, according to the present invention,
The detection means that has a mounting part inside the device sequentially detects the deformation of the device itself due to external force or heat that affects the positioning error, and learns the relationship between this detection information and the positioning error and uses the stored knowledge. Since the positioning error is calculated and corrected, it has become possible to perform positioning with ultra-high accuracy, which has never been obtained before.

Particularly, by combining the coarse movement mechanism and the fine movement mechanism, it is possible to realize a feeding device having a large stroke, high precision and high resolution.

Further, if the ultra-precision feeding device of the present invention is used for the feeding mechanism of the XY table, it is possible to carry out absolute positioning in a plane and three-dimensional positioning.

Also, when the ultra-precision feeding device of the present invention is used as a table transfer device for one axis direction, three-dimensional positioning can be performed.

[Brief description of drawings]

FIG. 1A is a control configuration diagram of an ultra-precision feeding device according to an embodiment of the present invention, and FIG. 1B is a conceptual diagram of the present invention.

2A and 2B are views showing the structure of the feeding device of FIG. 1, FIG. 2C is an exaggerated view of the deformed state of the force sensor, and FIG. It is a figure which exaggerates and shows the operating state of a mechanism.

FIG. 3 is a perspective view of a configuration example in which the feeding device of FIG. 1 is further embodied.

FIG. 4A is a diagram showing a pitch error of a ball screw shaft, FIG. 4B is a diagram showing a relationship between an external force and a positioning error,
FIG. 6C is a diagram showing the relationship between the output of the force sensor and the positioning error.

5A is a diagram showing a relationship between an input voltage and a displacement amount of a piezoelectric element, FIG. 5B is a diagram showing a state in which a pitch error is corrected, and FIG. 5C is a positioning by force deformation. It is a figure which shows the state which corrected the error.

FIG. 6A is a configuration diagram of an ultra-precision feeding device according to a second embodiment of the present invention, and FIG. 6B is a control system configuration diagram.

FIG. 7 is a diagram showing a more specific configuration example of the apparatus of FIG.

8A is a diagram showing the relationship between the output of the thermal deformation sensor of FIG. 7 and the positioning error, and FIG. 8B is a diagram in which the positioning error due to thermal deformation is corrected.

FIG. 9 is a diagram showing another configuration example of the thermal deformation sensor.

10A is a configuration diagram of an ultra-precision feeding device according to a third embodiment of the present invention, and FIG. 10B is a control system configuration diagram.

11A is a configuration diagram of an XY table of the present invention, and FIG. 11B is an external perspective view.

12A is a control configuration diagram of the XY table in FIG. 11, and FIGS. 12B and 12C are diagrams showing an example of a Z-axis direction small displacement actuator.

FIG. 13 is a diagram showing a basic physical phenomenon that occurs during machining of a machine tool.

[Explanation of symbols]

 1 Feed Device 2 Coarse Movement Mechanism 3 Fine Movement Mechanism 4 Ball Screw Shaft 5 Ball Nut 6 Ball 7 Base 8 Bearing Base 9 Bearing 10 Motor Support Wall 11 Drive Shaft 12 Joint Member 13 Linear Motion Guide Mechanism 14 Fixed Rail 15 Movable Rail 16 Micro Displacement actuator 17 Displacement sensor 18 Elastic member 19 Strain gauge 20 Fixed part 21 Movable part 22 Spring part 23 Encoder 24 Driven part 25 Force sensor 26 Elastic member 27 Strain gauge 28 Coarse control circuit 29 Drive circuit 30 Memory 31 Fine motion control circuit 32 Laser Length measuring device 33 Thermal deformation sensor 34 Reference member 35 Displacement sensor 36 Elastic member 37 Strain gauge 38 Base side fixing part 39 Reference member side fixing part 40 Spring part 51 Base 52 First table 53 Second table 54, 55 Linear motion Guide mechanism 56, 57 Feed mechanism 58 Ball screw Axis 59 Ball nut 60 Coarse movement mechanism 61 Fine movement mechanism 62 Fine movement mechanism 63 Track rail 64 Rolling element 65 Micro displacement actuator 66 Elastic member 67 Micro displacement element 68 Strain gauge 69 Coarse control circuit 70 Fine motion control circuit 71 Memory 72 Thermal deformation sensor 73 Force sensor 74 Z-axis position control circuit 75 Thermal deformation sensor 76 Distance meter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location B23Q 5/22 520 C 5/28 C 15/18 15/22 (72) Inventor Kazushi Kazushi 3-11-6 Nishigotanda, Shinagawa-ku, Tokyo Teichique-Inside

Claims (13)

[Claims] 1. A drive means, a feed amount detection means for detecting a feed amount, information about a shape error for each feed position, information about thermal deformation due to temperature distribution of an apparatus, and information about deformation due to an external force. Information detecting means provided inside the apparatus for sequentially detecting any one of them, and the relationship between the detection information of the information detecting means and the positioning error and the relationship between the shape error and the positioning error of other parts of the apparatus are stored in advance as knowledge. Storage means; and control means for driving the drive means by obtaining a correction control amount based on the detection information and the storage information sequentially detected by the feed amount detection means and the information detection means. An ultra-precision feeder that does. 2. The ultra-precision feed according to claim 1, wherein the control means learns in advance the relationship between the positioning error, the feed amount detection means and the information detection means, and the correction control amount of the drive means. apparatus. 3. The ultra-precision feeding device according to claim 2, wherein the learning is performed by a distance detecting means that measures the distance from the reference position. 4. The ultra-precision feeding device according to claim 1, wherein the driving means is constituted by an actuator group in which a coarse movement mechanism and a fine movement mechanism are arranged in series, and a positioning error is corrected by the fine movement mechanism. 5. The ultra-precision feeding device according to claim 1, wherein the force sensor is provided in a path through which the external force of the device is transmitted. 6. The ultra-precision feeding device according to claim 1, wherein the deformation sensor for detecting thermal deformation detects the amount of expansion and contraction in the feeding direction of a portion that has a great influence on the positioning error. 7. The ultra-precision feed device according to claim 1, wherein the coarse movement mechanism is a screw feed mechanism. 8. The fine movement mechanism includes a piezoelectric element, an electrostrictive element, an actuator that expands and contracts by utilizing thermal expansion, an actuator that expands and contracts by using fluid pressure, an actuator that uses a voice coil, an actuator that uses a magnetostrictive element, etc. The ultra-precision feeding device according to claim 1, further comprising a minute displacement unit that expands and contracts in proportion to the command value of. 9. The fine movement mechanism comprises a minute displacement means and an elastic member which is deformable in the displacement direction of the minute displacement means and is rigid in a direction orthogonal to the displacement direction. The ultra-precision feeding device described in 8. 10. The ultra-precision feeding device according to claim 8, wherein the fine movement mechanism has a deformation sensor arranged in parallel with the fine displacement means, and the fine displacement means is controlled by feedback control. 11. A base, a first table movably mounted on the base via a linear motion guide mechanism in the X-axis direction, and a linear table on the first table via a linear motion guide mechanism. A second table movably arranged in a Y-axis direction orthogonal to the X-axis; a feeding mechanism provided between the base and the first table to feed the first table in the X-axis direction; A feed mechanism that is provided between the first table and the second table and that feeds the second table in the Y-axis direction, and that serves as the feed mechanism in the X-axis direction and the Y-axis direction. An XY table capable of correcting a planar positioning error in the X-axis direction and the Y-axis direction by using the ultra-precision feeding device described in (3). 12. A warp amount detecting means for sequentially detecting a warp amount in a Z-axis direction orthogonal to the X-axis and the Y-axis of the base, a distance between the base and the first table, a first table and a second table. Distance detecting means for detecting a distance between the tables in the Z-axis direction,
And a minute displacement generating means for generating a displacement in the Z-axis direction in the linear motion guiding device, and the detection information of the warp amount detecting means and the distance detecting means and the X information.
The relationship between the positioning errors in the Z-axis direction for each feed position in the Y-axis direction is stored in advance as knowledge, and the Z-axis direction in the Z-axis direction is detected based on the detection information sequentially detected by the warp amount detection means and the distance detection means. A control means for determining the correction control amount and controlling the minute displacement generating means in the Z-axis direction is provided, and X,
An XY table capable of correcting a three-dimensional positioning error in the Y and Z axis directions. 13. A base, a table movably arranged on the base via a linear motion guide mechanism, and a feed mechanism provided between the base and the table for driving the table. An ultra-precision feeding device according to any one of claims 1 to 10 is used as the feeding mechanism, and on the other hand, a warping amount for sequentially detecting a warping amount in a height direction orthogonal to a feeding direction of the base. A detection means and a distance detection means for detecting a distance between the base and the table are provided, and the linear movement guide device is provided with a minute displacement generation means for generating a displacement in a height direction orthogonal to the feed direction, The relationship between the detection information of the warp amount detecting means and the distance detecting means and the positioning error in the height direction for each feed position of the table is stored in advance as knowledge, and the detection is sequentially detected by the warp amount detecting means and the distance detecting means. Information and before Table feeding apparatus characterized by based on the stored information seeking compensation control amount in the height direction is provided a control means for driving the micro-displacement generation means.