JP2002127003A - Precision machining device with attitude control device and attitude control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precision machining device with an attitude control device and its attitude control method for machining articles including a silicon wafer, requiring extremely precise shaping accuracy and finished surface roughness. SOLUTION: The precision machining device with the attitude control device comprises a grinding wheel and its rotating device and a work and its rotating device placed on individually independent tables and a grinding wheel spindle and a work spindle arranged to be coaxially opposed to each other, wherein an attitude control plate is provided one of the two tables, the attitude control plate being simultaneously rotatable around a contact C as a supporting point at a minute angle toward any space and the attitude control plate having minute-angle rotation utilizing the minute displacement of a super magnetostrictive actuator. In attitude control, a control system employing a hysteresis model is used to compensate for the hysteresis characteristic of a super magnetostrictive element of the super magnetostrictive actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing an article requiring extremely precise shape accuracy and surface roughness, such as a silicon wafer, a semiconductor device, a magnetic disk substrate or a crystal oscillator substrate. More specifically, the present invention relates to an apparatus for adjusting a relative position (alignment) between a work (workpiece) and a processing means such as a grindstone, and controlling a mutual posture, and a control method therefor. .

[0002]

2. Description of the Related Art In recent years, there has been a need for downsizing, high performance, high productivity, and low price of so-called electronic devices such as computers, and ICs, Ls, which occupy an important part thereof,
There is an urgent need to increase storage capacity and reliability and reduce production costs for SI and VLSI, and also to urgently demand labor and energy savings as a whole industry. Under these circumstances, the dimensional accuracy and / or surface area of the silicon wafer, semiconductor device, magnetic disk substrate or quartz oscillator substrate, etc., which are the raw materials of these elements and the parts supporting the periphery, are processed. There is a significant demand for improved roughness. On the other hand, there is also a need to respond to demands for lowering the cost of the processing process and dramatically improving productivity, and therefore, it is necessary to develop processing methods and equipment based on completely new ideas. I have.

In particular, silicon wafers, which are raw materials for ICs, LSIs, and VLSIs, are required to have uniform thickness, improved dimensional stability, and improved surface roughness at the processing stage. The processing conditions in the polishing process for obtaining the wafer and the demands on the accuracy and stability of the apparatus itself have become much more severe. That is, specifically, accuracy at the level of nm (nanometer) is required. Further, the diameter (diameter) of the wafer is also being improved for the purpose of improving the yield in all processes from the wafer to the product and improving the productivity, specifically, 300 mm.
Production of (12 inch) diameter silicon wafers has also begun on a trial basis.

Electronic parts such as ICs, LSIs and VLSIs are manufactured by mirror-finishing a wafer obtained by slicing a single crystal ingot of silicon or another compound semiconductor, and then writing and dividing a large number of fine electric circuits into small parts. It is manufactured based on flake-shaped semiconductor element chips,
The mirror-finished silicon wafer was generally manufactured through the following series of manufacturing processes. That is, after performing the outer peripheral grinding of the silicon single crystal ingot manufactured by the single crystal pulling method, for example, performing orientation flat processing for positioning in the crystal direction, slicing with an inner peripheral blade saw or a wire saw, and as-cutting. Obtain a wafer. After the as-cut wafer is chamfered at the outer peripheral portion by beveling, the wafer is finished to have uniform thickness, parallelism, flatness, straightness, and a certain surface roughness by double-sided lapping. The obtained wrapped wafer is subjected to an etching process with an acid or an alkali to remove a processing damage layer generated by the lapping, and then a mirror finish by pre-polishing and polishing. The mirror wafer obtained here must have excellent surface roughness and shape accuracy. The surface roughness Ra of the final mirror-finished surface of a φ300 mm (12 inch) wafer is desirably 1 nm or less, the flatness is 0.2 μm / 300 mm or less, and the total processing amount from the as-cut wafer to the final mirror-finished wafer is 6
It is about 0 μm.

Conventionally, the operation of each of the above-mentioned main steps of lapping, pre-polishing or polishing is as follows.
In general, a large-sized processing machine provided for each process is used to simultaneously process a plurality of workpieces. However, as the size of wafers has become larger and larger,
Due to the handling characteristics, the size of the equipment has become limited, and it is difficult to increase the precision at the same time as the equipment is enlarged. Many studies have been made on a so-called single-wafer method in which processing is performed one by one, and a method in which processing is performed in an integrated manner.

The grinding method using these diamond grindstones has three main movements: rotation of the grindstone, feed of a spindle supporting the grindstone, and positioning of the work. It is possible to perform precision machining by controlling these with high precision.However, in order to perform consistently from rough machining to machining in the ultra-precision area with one device and machine, one of the major movements described above In addition, it is necessary to control the feed of the spindle in a wide range with extremely high accuracy. Conventionally, for the feed control of this spindle in general cutting or grinding, for example, a method that applies feed by a precision screw, servo motor or piezoelectric actuator is often used, but from the purpose of covering a wide range with high accuracy. It is not enough, and it is hard to say that it is sufficient for machining in an ultra-precision machining region in which the attitude (alignment) control of the fine feed under a large load is extremely precise. Furthermore, the thermal displacement caused by the mechanical body and the base supporting each part due to the heat generated by friction due to the mechanical factors involved in the processing leads to a delicate misalignment between the work axis and the axis of the grinding wheel axis. It has been pointed out that it adversely affects the accuracy of high flatness and flatness required for processing a larger diameter wafer.

The present inventors have already disclosed in Japanese Patent Application No. 2000-152833, in order to solve the above-mentioned problems.
Using a cup-type precision diamond grindstone, the processing method is a form in which infeed (feeding) cutting is performed. The grindstone and the work are placed on independent tables, respectively, and the grindstone axis and the work axis oppose each other in the horizontal direction. And the positioning is performed using both a superprecision lap screw and a giant magnetostrictive actuator, and the attitude control (alignment) between the grinding wheel axis and the work axis is always performed using the giant magnetostrictive actuator.
We have proposed a precision processing device characterized by performing. The attitude control referred to here means that the thermal displacement of the machine body and the base supporting each part caused by the heat generated by the mechanical factors and the friction caused by the processing causes the minute and complicated movement between the grinding wheel axis and the work axis. This is performed in order to correct the deviation, leading to the deviation. That is, the correction must be performed in real time with extremely high responsiveness.
The characteristic required of this attitude control device is that, for example, a table on which an article with a large load in the ton order is minutely displaced in real time with nanometer accuracy, and a giant magnetostrictive actuator is used as a driving force for the minute displacement. Is used. However, the giant magnetostrictive element of the giant magnetostrictive actuator has a hysteresis characteristic, and is thermally expanded and deformed by Joule heat generated when the giant magnetostrictive actuator is operated and heat generated by eddy current loss. In the case of performing control by ordinary linear control using a giant magnetostrictive actuator, there are the following problems, and improvements have been demanded.

The rod-shaped magnetostrictive element of a giant magnetostrictive actuator undergoes a dimensional change by applying a magnetic field and is displaced, and the magnitude of the displacement value changes depending on the strength of the magnetic field. This phenomenon is applied to the actuator. -ing In a concrete use, a deviation of the posture between the grinding wheel axis and the work axis is constantly detected during the machining operation, and the numerical value of the detected deviation is converted into a current value to be input to the coil of the giant magnetostrictive actuator using a microcomputer.
By continuously changing the current value in response to the fluctuating shift and changing the magnetic field, the magnetostrictive element is continuously displaced and drives the attitude control plate. That is, the most important point of this device is that the giant magnetostrictive actuator operates in real time to move the attitude control plate in response to a deviation from the detected set value. However, since the magnetostrictive element of the giant magnetostrictive actuator has a hysteresis characteristic, as is well known, it is undeniable that a slight deviation occurs in terms of following a continuous change of the magnetic field. The deviation caused by the hysteresis characteristic is extremely small and is not so large as to be taken up as a problem in the processing of a silicon wafer of a conventional size. Is becoming a problem.

In order to apply a magnetic field to the rod-shaped magnetostrictive element of the giant magnetostrictive actuator to cause a dimensional change,
This is performed by passing a current of a predetermined current value through a cylindrical driving coil disposed around the magnetostrictive element. On the other hand, however, the flow of electric current causes the drive coil to generate heat due to the Joule effect, and the heat is transmitted to the rod-shaped magnetostrictive element, causing thermal expansion, which significantly reduces the accuracy of attitude control. Let me know. Furthermore, when an electric current is applied to the driving coil, an eddy current is generated, and the eddy current loss leads to heat generation of the magnetostrictive element, which also causes a reduction in the accuracy of the attitude control.
That is, the attitude control function of detecting the deviation between the grinding wheel axis and the work axis, accurately following the deviation, and correcting the deviation in real time becomes insufficient. Giant magnetostrictive actuator
If a permanent magnet is built in besides the driving coil, it is not necessary to apply a magnetic bias by an offset current, and it is possible to suppress the Joule heat by that much. This is not enough for applications requiring precise control.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have conducted intensive studies and have studied a device for controlling the attitude of a large-load article very precisely and accurately by using a giant magnetostrictive actuator. As a result, the control system that compensates for the delay and deviation of the response caused by the hysteresis characteristic of the magnetostrictive element is incorporated, and the decrease in accuracy caused by the Joule heat generated from the coil of the giant magnetostrictive actuator and the heat generated by the eddy current loss is reduced. The incorporation of the means for solving the problem has revealed that the use of a giant magnetostrictive actuator significantly improves the responsiveness and accuracy of the attitude control device, and has completed the present invention. It is an object of the present invention to provide a precision machining device with an attitude control device provided with an accurate attitude control mechanism system. Still another object of the present invention is to provide a control method therefor.

[0011]

An object of the present invention is to provide a grinding wheel and its rotating device and a work and its rotating device which are mounted on independent tables, respectively, so that the grinding wheel shaft and the work shaft coaxially oppose each other. In one of the two tables, one of the two tables is provided with an attitude control plate, and the attitude control plate is provided with a contact C as a fulcrum at a small angle in an arbitrary direction around the contact point. It is possible to achieve simultaneous rotation, and minute rotation of the attitude control plate is achieved by using a minute displacement of a giant magnetostrictive actuator.

Further, another object of the present invention is to dispose the grindstone and its rotating device and the work and its rotating device on independent tables, respectively, so that the grindstone shaft and the work shaft are coaxially opposed to each other. In the precision machining apparatus arranged, one of the two tables is provided with an attitude control plate, and the attitude control plate is formed at a small angle in a direction of an arbitrary space around the contact C as a fulcrum. Simultaneous rotation is possible, and the micro-rotation of the attitude control plate is performed using the micro-displacement of the giant magnetostrictive actuator.In a precision machining device with an attitude control device, a control system applying a hysteresis model, Achieved by controlling the attitude control plate, which compensates for the hysteresis characteristics of the giant magnetostrictive element of the giant magnetostrictive actuator It is. In the above control method,
The giant magnetostrictive actuator that drives the attitude control plate
By a control system using an inverse model based on the Priesach model, to compensate for the hysteresis characteristics of the giant magnetostrictive element, further, the giant magnetostrictive actuator, by flowing a fluid around the drive coil, It is characterized in that the giant magnetostrictive element of the giant magnetostrictive actuator is maintained at a constant temperature. The eddy current loss is minimized by making the giant magnetostrictive element a thin cylindrical shape.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view showing the external appearance of a precision machining apparatus main body with an attitude control device according to the present invention, FIG. 2 is an external view of an attitude control plate, FIG. Fig. 2 shows a side view. Attitude control plate 5 used in the present invention
Is mounted on one of the tables 3 and 4 on which the grindstone 6 and its rotating device 7 or the work 8 and its rotating device 9 are mounted, and is generated by mechanical factors and friction accompanying the processing. This is for correcting a slight deviation of the posture of the axis of the work axis and the axis of the grindstone axis caused by the displacement caused by heat or vibration. The slight deviation of the attitude between the axes of both axes is always detected, and the detected deviation is numerically processed by a microcomputer, and the required displacement value of each giant magnetostrictive actuator is applied to each giant magnetostrictive actuator. Input, and angles (θx, θy and θ
up to z), with the contact C of the attitude control plate as a fulcrum,
A minute rotation about the Z axis and a minute rotation about the X axis passing through the contact point C are performed. The above-described detection of the deviation between the axes is always performed continuously during the machining operation, and the processing of the numerical values, the command to the giant magnetostrictive actuator, and the operation are performed instantaneously in real time. It is characterized by.

The hysteresis characteristic of the giant magnetostrictive element is as follows.
After applying a magnetic field to cause a dimensional change in the giant magnetostrictive element (rod), the phenomenon does not return to the original state when the magnetic field is removed. When a giant magnetostrictive actuator is used as the driving force of the attitude control plate as in the present invention, the hysteresis characteristic leads to a difference between an input value (command value) corresponding to a target displacement value and an actual output value, and deteriorates accuracy. Therefore, it is necessary to predict in advance of the recovery due to the hysteresis characteristic and to incorporate a control system for compensating for it.

In the present invention, as a control system for compensating the above-mentioned hysteresis characteristics, a hysteresis model described by a mathematical function (a straight line, an arc, a spline, etc.), preferably an inverse model based on a Prisach model is used. Features. The Preisach model is for predicting changes in the magnetization state of a magnetic material,
The present invention is characterized in that the present invention is applied to a simulation of a phenomenon showing a hysteresis characteristic of a giant magnetostrictive material. That is, one actuator is regarded as a set of hysteresis elements that minimizes hysteresis, and a table relating to the distribution of hysteresis elements is created. Since a current input value for outputting a target displacement amount of the actuator can be calculated from this table, a prescribed displacement path can be taught by canceling the hysteresis characteristic. That is, this makes it possible to deal with the same handling as simple linear control. FIG. 6 shows the concept of hysteresis compensation by the Preisach model. That is, it is considered that the plant P is regarded as a product of the hysteresis H and the linear plant P ₀ , and this is multiplied by an inverse function of the hysteresis to cancel the hysteresis. If N is exactly the inverse function of the hysteresis, the hysteresis characteristic can be canceled and the characteristic of the plant can be treated as linear. u is an input value and y is an output value. By using a control model based on an inverse model to which this Priesach model is applied as a control model of three giant magnetostrictive actuators attached to the attitude control plate of the present invention, X, Y,
At the same time, the three axes of Z are angled in units of 1/100 second (θx, θy
And θz), posture control that responds accurately and in real time is possible.

Further, in the present invention, in order to prevent the influence of the Joule heat generated from the driving coil 11 of the giant magnetostrictive actuator and the thermal expansion of the giant magnetostrictive element due to the heat generated by the eddy current loss, the temperature is controlled. Is performed. As described above, in order to displace and drive the giant magnetostrictive element of the giant magnetostrictive actuator, it is necessary to supply a current to the drive coil to generate a magnetic field. Generally, a coil for generating a magnetic field generates Joule heat by passing an electric current, and the heat is transmitted to the giant magnetostrictive element to cause the element to thermally expand. Furthermore, an eddy current is generated by passing an electric current through the coil, and the eddy current loss causes heat generation of the magnetostrictive element, which also leads to thermal expansion of the giant magnetostrictive element, which significantly lowers the accuracy of the attitude control plate. In order to avoid such an undesired phenomenon, the coil portion 11 is generally forcibly cooled with a fluid having a high heat capacity such as water. In the present invention, however, a certain level is used instead of the active cooling. The flow of the fluid controlled in step (1) is caused to flow through the jacket 13 provided around the coil for a certain period of time to bring the coil to an equilibrium temperature, and the main point is to maintain the equilibrium temperature during processing.

By adopting such a system, it is possible to use water as a cooling fluid, and it is also possible to use air or the like without employing a liquid cooling system which is complicated and requires heavy equipment. It is possible to sufficiently follow the temperature adjustment by the gas. That is, after allowing a certain degree of thermal expansion of the giant magnetostrictive element due to Joule heat or eddy current loss, the temperature is raised to a certain constant temperature (equilibrium temperature), and accurate temperature maintenance at the equilibrium temperature is performed. Specifically, for example,
Temperature controlled compressed air can be used. By allowing air to flow around the coil that generates heat, particularly between the giant magnetostrictive materials, accurate temperature maintenance can be achieved. For example, when the giant magnetostrictive actuator used in the present invention is continuously operated at an average current value and compressed air whose temperature is controlled at 20 ° C. is flowed at a flow rate of 100 L / min, the giant magnetostrictive element is about 5 ° C. It was confirmed that the temperature reached an equilibrium state by the temperature rise, and thereafter, the temperature was maintained at a temperature accuracy of ± 0.2 ° C.

An embodiment of the attitude control plate constituting the precision machining apparatus with the attitude control apparatus according to the present invention will be specifically described with reference to FIG. In the drawing, the attitude control plate 5 is composed of two plates A and B, and the plates A and B are connected at a contact point C. There is a narrow gap F between the upper plate A and the lower plate B so as to avoid direct contact between the plates A and B. In actual use, the plate material B is fixed to the grindstone table 3 or the work table 4, and the grindstone 6 and its rotating device 7 or the work 8 are placed on the plate material A.
And its rotating device 9 are mounted. Of the upper plate material A,
One end perpendicular to the side where the joining point C is located, a tip rod D1a
A giant magnetostrictive actuator D1 is disposed so as to abut. Further, giant magnetostrictive actuators D2 and D3 are arranged below the side of the plate A opposite to the side where the joining point C is located. The tip rods D2a and D3a of each giant magnetostrictive actuator are configured to abut the lower surface of the upper plate A. It is important that at least the joint point C of the attitude control plate constituting the present invention is made of a material that can be elastically deformed.

The tip rod D of the giant magnetostrictive actuator D1
Due to the linear motion 1a in the X-axis direction, the upper plate material A can be slightly rotated and displaced around the joint C by a minute angle (Δθy) around the Y-axis in units of 1/100 second. As described above, since the material forming the joint point C is a material that undergoes elastic deformation, it is displaced when a preload is applied by a giant magnetostrictive actuator, and returns to its original position when the preload is removed. is there. Further, the upper plate material A moves in the Y-axis direction around the X-axis passing through the joint C by the linear action of the tip rods D2a and D3a of the giant magnetostrictive actuators D2 and D3 with the same displacement amount in the Y-axis direction. A minute tilt displacement at a minute angle (Δθx) in units of / 100 seconds is possible. That is, by the action of the giant magnetostrictive actuators D2 and D3, the upper plate material A can be displaced so as to open and close the gap F up and down with the side having the joint point C as an axis (X axis). Further, by changing the amount of displacement of the tip rods D2a and D3a of the giant magnetostrictive actuators D2 and D3 in the Y axis direction, the upper plate material A
A minute rotational displacement at a minute angle (Δθz) in units of / 100 seconds is possible. That is, by controlling the movements of the three giant magnetostrictive actuators, a small deviation (deviation) between the grinding wheel axis and the work axis aligned along the Z axis is corrected in a three-dimensional space. Posture control can be performed.

As a specific correction means, an accurate position of the grindstone axis and the work axis is set in advance, and the position is used as a reference point. Detected by a displacement sensor (not shown) in each attached direction and required Δθx, Δθ by computer
It converts y and Δθz into magnetic field command values, instructs each giant magnetostrictive actuator, activates each giant magnetostrictive actuator, and controls the attitude of the apparatus. Here, each displacement sensor may be arranged at a position where displacement information of the three giant magnetostrictive actuators D1, D2, and D3 can be obtained. The type of the displacement sensor is not particularly limited, but it is particularly preferable to use a capacitance type displacement sensor as one used for such a precise and precise application. In the present invention, when converting the value of the displacement detected by the displacement sensor into a command value to the giant magnetostrictive actuator, the above-described control system based on the inverse model for canceling the hysteresis characteristic is used.

The material of the material for the attitude control plate constituting the present invention is not particularly limited.
As described above, since it is required to be structurally tough and high in rigidity, to have a preferable elastic deformation, and to exhibit spring elasticity and to be less deformed by heat, specifically, a steel material, Specific examples that are more realistic and preferable are those that minimize deformation due to heat,
For example, austenitic steel and the like can be mentioned. As a specific practical example, for example, there can be exemplified a method in which a gap F is inserted into a central portion of a steel plate which can be integrally elastically deformable by using electric discharge machining or the like and a part thereof is left as a joint point C. It is preferable that the material of the other structural parts of the device of the present invention is also structurally tough, high in rigidity, and less deformed by heat.

The giant magnetostrictive actuator referred to in the present invention is:
For example, as disclosed in JP-A-64-34631, a polycrystal or single crystal of an alloy in a specific ratio of a specific rare earth element and an iron group element composed of nickel, cobalt, iron and the like, A giant magnetostrictive material that causes a strong dimensional change when a magnetic field is applied is applied as a magnetostrictive element. Usually, a rod Da made of a giant magnetostrictive material is placed at the center, and its periphery is surrounded by a driving coil 11.
An arrangement in which permanent magnets 12 are arranged above and below is preferably used as an arrangement in which Joule heat is hardly generated. The giant magnetostrictive actuator of the present invention comprises a grindstone table 3 and a work table 4.
In order to displace the distance of ± several μm with nanometer accuracy in a state where an article with a large load is placed, it is required to minimize the deviation of the displacement amount due to Joule heating, It is preferable to use one having a built-in permanent magnet.

The precision machining apparatus with the attitude control device of the present invention
As described above, it can be used for precision machining of a work requiring extremely high finished surface roughness and shape accuracy, for example, a silicon wafer having a large diameter exceeding 300 mmφ. The grindstone to be used is not particularly limited, but it is particularly preferable to use a diamond grindstone which is superior in rigidity and grinding ability, since the infeed (feeding) cut is performed as described above. The shape is preferably a cup shape. The diamond cup type grindstone here means a diamond fine powder as abrasive grains, a hard resin such as phenol, a special alloy, a ceramic or the like as a binder, or a material fixed by means of electrodeposition or the like. In this case, it is a ring shape, and the edge-shaped side surface is used. The size (count) of the diamond abrasive grains to be used is not particularly limited, but for the purpose of precision machining, at least JI
200 in the standard of S-R6001 (particle size of abrasive)
Finer than No. 0, that is, dv-50 value is 6.7 ± 0.6
It is preferable to use one having a size of μm or less. With the above specifications, if applied to such a purpose, for example, lapping, etching, pre-polishing, polishing, etc., can shorten the processing steps over several stages, and can be continuously performed with only one processing device and one grinding wheel. And efficient processing can be performed.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

[0025]

EXAMPLE A silicon wafer having a size of 300 mm was processed using the apparatus shown in FIG. The as-cut wafer sliced from the ingot was set to a certain degree of parallel by rough lapping, and a workpiece close to the finished dimensions and having a degree of parallelism was used as a workpiece. As a grindstone, a cup-shaped resin bond grindstone using fine diamond powder was used. Using water as a processing liquid, processing was performed for about 10 minutes. As a result, a surface having a surface roughness of 0.8 nmRa could be obtained. The allowance during that time was about 2 μm, and the flatness could achieve 0.20 μm or less for a diameter of φ300 mm. That is, if it is performed in the usual way, lapping, etching, pre-polishing,
Polishing required several steps of processing, and a total of steps of about 30 minutes could be performed in only one step without replacing one grindstone in the middle and in only about 10 minutes.

[0026]

As described above, by using the precision processing apparatus according to the present invention, it is possible to carry out finishing processing of a silicon wafer, which has conventionally been performed in several steps, in one step, and to achieve a large diameter of φ300 mm. And a flatness of 0.20 μm or less with respect to the silicon wafer. This not only made it possible to deal with large-diameter wafers, which was a major problem in the past, but also made it possible to drastically shorten the process itself and significantly improve accuracy.
The processing object is not limited to silicon wafers,
For example, it is possible to process difficult-to-cut materials such as ceramics or composite materials, and the effect on the industry is extremely large.

[Brief description of the drawings]

FIG. 1 is a side view showing an external appearance of a main body of a precision processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing an embodiment of a posture control plate.

FIG. 3 is a front view showing an embodiment of a posture control plate.

FIG. 4 is a side view showing an embodiment of a posture control plate.

FIG. 5 is a sectional view of a giant magnetostrictive actuator used in the present invention.

FIG. 6 is an explanatory diagram showing the concept of hysteresis compensation using the Preisach model.

[Explanation of symbols]

1, 1 ': Ultraprecision lap screw, 2, 2': Static pressure air guide, 3: Grinding stone table, 4: Work table, 5: Attitude control plate, 6: Grinding stone, 7: Grinding stone rotating device, 8: Work, 9: Work rotating device, 10: Bed, 11: Coil, 12: Permanent magnet, 13: Jacket, 14, 1
4 ': temperature sensor, A: upper plate, B: lower plate,
C: contact point, D, D1, D2, D3: giant magnetostrictive actuator, Da, D1a, D2a, D3a: rod of giant magnetostrictive actuator, F: gap,

Continued on the front page (71) Applicant 000233332 Hitachi Via Mechanics Co., Ltd. 2100, Kamiimaizumi, Ebina-shi, Kanagawa (72) Inventor Hiroshi Eda 1477-1 Otacho, Tomobe-cho, Nishi-Ibaraki-gun, Ibaraki Pref. 6--9 Ayukawacho, Hitachi B-403 (72) Inventor Ryo Kondo 6-9-9 Ayukawacho, Hitachi, Ibaraki A-102 (72) Inventor Takuji Tajima 2100 Kamimaizumi, Ebina-shi, Kanagawa Hitachi Hitachi, Ltd. (72) Inventor Kazu Watanabe 2100 Kamiimaizumi, Ebina-shi, Kanagawa Prefecture F-term in Hitachi Via Mechanics Co., Ltd. (reference) 3C029 EE02 3C034 AA08 CA12 CA13 CB08

Claims (4)

[Claims] 1. A precision machining apparatus in which a grindstone and its rotating device, and a work and its rotating device are mounted on independent tables, respectively, and a grindstone shaft and a work shaft are coaxially opposed to each other. In one of the two tables, an attitude control plate is provided, and the attitude control plate is capable of simultaneously rotating at a small angle in the direction of an arbitrary space around the contact C as a fulcrum, A precision machining apparatus with a posture control device, wherein minute rotation of the posture control plate is performed using minute displacement of a giant magnetostrictive actuator. 2. The attitude control plate has a structure in which two plate members A and B are vertically connected via a contact point C, and the material forming the contact point C is a material that undergoes elastic deformation, and is located upward. The giant magnetostrictive actuator D1 is arranged so that the tip rod abuts on one side of the plate material A that is orthogonal to the side of the contact C, and the tip rod is located below the side opposite to the side of the contact C. 2. The precision machining apparatus according to claim 1, wherein giant magnetostrictive actuators D2 and D3 are arranged so as to abut on a lower part of A. 3. A precision machining apparatus in which a grindstone and its rotating device, and a work and its rotating device are mounted on independent tables, respectively, and a grindstone shaft and a work shaft are coaxially opposed to each other. In one of the two tables, an attitude control plate is provided, and the attitude control plate is capable of simultaneously rotating at a small angle in the direction of an arbitrary space around the contact C as a fulcrum, In addition, the micro-rotation of the attitude control plate is performed by using the micro displacement of the giant magnetostrictive actuator. In the precision machining equipment with the attitude control device, the giant magnetostrictive element of the giant magnetostrictive actuator is controlled by a control system applying a hysteresis model. A method for controlling a posture control plate, wherein the hysteresis characteristic of the plate is compensated. 4. The control method for an attitude control plate according to claim 3, wherein the super magnetostrictive element of the giant magnetostrictive actuator is maintained at a constant temperature by flowing a fluid through the giant magnetostrictive actuator.