JPH09106897A - Processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain processing with its high-precision efficiency for a surface such as optical lens by removing a surface layer with its uniform thickness while the shape precision of a processing face of a material to be processed is maintained by means of radial reaction generated by means of plasma. SOLUTION: A spherical face lens 10 is placed on a work table 1 of a lens processing device. A chamber 9 is closed, and the chamber 9 is temporarily de-pressurized by means of a gas discharge system 5. A reaction gas is supplied by means of a gas supply system, the pressure in the chamber is set to a specified pressure. A plasma generating unit of a processing electrode 2 is made close to a predetermined distance from the surface of a processed lens 10. High- frequency power is applied to the processing electrode 2 by means of a power supply system 3. An arc-shaped local plasma is generated along the plasma generating unit of the processing electrode 2, and radical of reaction gas is generated by means of this plasma. The radical of the reaction gas and the processed lens 10 react, the processed lens 10 reacts, and the surface of the processed lens is processed. The generated gas is discharged by means of the gas discharge system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing a shape of an article, and more particularly to an apparatus suitable for manufacturing a lens used for optical products such as a camera, a microscope, a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art A glass lens is mainly used for an optical system of an optical product such as a camera, a microscope, and a semiconductor manufacturing apparatus. Conventionally, a glass lens is manufactured through the following steps.

Pressing step: A step of forming a glass block by press-forming from molten glass.

Grinding step: a step of manufacturing a rough lens having a desired curvature by grinding a glass block with a grinding machine.

Smoothing step: a step of removing a scratch or a crack layer on the surface of the rough surface lens by moving a metal dish on which diamond pellets are attached on a work. In some cases, instead of the diamond pellets, abrasive grains having a large grain size may be supplied between the metal dish and the work for processing. Also called sanding process.

Polishing step: A step of polishing a rough surface lens with a polishing polisher to further remove scratches and crack layers and to correct a shape error generated in the grinding step.

The polishing process is performed for the purpose of removing scratches and crack layers generated in the grinding process and the smoothing process. However, like the smoothing process, the polishing process is also a machining process that utilizes plastic deformation and brittle fracture, so the surface of the workpiece is
A work-affected layer may be generated due to fine cracks and strains. This becomes a problem when high optical performance is required.

On the other hand, a strain-free processing method utilizing a radical reaction is described in JP-A-1-125829. In this processing method, the one using plasma is particularly called plasma CVM (Mori et al., Proceedings of the Spring Meeting of the Precision Engineering Society Spring Conference P. 637 1992). The plasma CVM is based on the following principle. That is, under high pressure, plasma is generated by the processing electrode installed near the workpiece. A reaction gas having a high electronegativity such as halogen is supplied to this plasma. As a result, the reaction gas is dissociated, radicals rich in reactivity are generated, and the radicals react with the surface of the workpiece. The surface of the work piece is processed by continuously vaporizing the product generated by the reaction. In addition, as the reaction gas, a gas having a property of reacting with the workpiece and vaporizing the product is selected and used.

According to this processing method, since plasma is generated under high pressure, it is possible to generate a high concentration of radicals which has never been obtained. Therefore, a high processing speed comparable to machining can be obtained. Further, because of the high pressure, it is possible to generate the localized plasma only in the area around the processing electrode where the electric field strength is high.
As a result, the processing region can be limited to the vicinity of the processing electrode, and processing with extremely high spatial resolution depending on the shape of the processing electrode can be achieved. Furthermore, since mechanical processing uses physical phenomena such as plastic deformation and brittle fracture to damage the machined surface, plasma CVM chemically processes the machined surface, so that the machined surface has defects and defects. There is no distortion layer and there is no strain.

In the plasma CVM, there is a correlation between the processing time and the processing amount. Therefore, the machining amount can be controlled by moving the machining electrode and the workpiece relative to each other at a predetermined time or speed according to the required removal amount. From this characteristic, by using numerical control as disclosed in JP-A-4-246184, an insulator such as glass or ceramics, a semiconductor such as silicon single crystal, and a conductor can be processed with high precision.

[0011]

However, when an optical lens is processed by using the plasma CVM, it is difficult to perform the processing with high accuracy and efficiency.

The present invention is a processing apparatus for processing by the reaction of radicals generated by plasma, and can remove a surface layer having a uniform thickness while maintaining the shape accuracy of the processed surface of the workpiece. It is an object of the present invention to provide an apparatus suitable for removing the work-affected layer on the surface and improving the surface roughness.

[0013]

In order to achieve the above object, according to the present invention, a support portion for mounting a workpiece, a gas supply portion for supplying gas, and a local An electrode for generating plasma, and a moving means for moving the electrode relative to the work piece, and a portion of the electrode facing the work piece is formed in the longitudinal direction after the work piece is processed. The moving means has a shape corresponding to the desired shape in, and the workpiece facing portion, which is a portion of the electrode facing the workpiece, faces the workpiece, and the electrode moves the workpiece. A processing apparatus is provided which moves the electrode relative to the workpiece in a direction perpendicular to the longitudinal direction while aligning with the normal line of the surface of the workpiece.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A lens processing apparatus according to an embodiment of the present invention will be described with reference to FIG.

The lens processing apparatus of the present invention uniformly removes a work-affected layer generated on the surface of a spherical lens by mechanical processing while maintaining the surface accuracy of the spherical lens formed by mechanical processing. This is a device for improving the surface roughness. A work table 1 for mounting a lens 10 to be processed and a processing electrode 2 for locally generating plasma on the surface of the lens 10 to be processed are provided inside a chamber 9.

The machining electrode 2 is shown in FIGS. 5 (a), 5 (b) and 6
As described above, the portion facing the lens to be processed is an arc-shaped blade-shaped electrode. The length of the processing electrode 2 in the longitudinal direction is set to a length that can cover the maximum diameter portion of the lens 10 to be processed. In addition, the radius of curvature of the arc of the portion of the processing electrode 2 facing the lens to be processed is the lens 1 to be processed.
The radius of curvature of the spherical surface after processing of 0 is set to the length obtained by adding the interval (gap length) between the processing electrode 2 and the lens 10 to be processed. Therefore, the lens 10 to be processed of the processing electrode 2
As shown in FIG. 5A, the portion opposed to is positioned along the surface of the lens to be processed 10 with a constant distance from the lens to be processed 10.

The portion of the processing electrode 2 facing the lens to be processed is a plasma generating portion for generating local plasma. In the processed electrode 2 shown in FIGS. 5A and 5B, the plasma generation unit is a flat surface as shown in FIG. 7A, but the plasma generation unit is not limited to the flat surface and the plasma is generated as shown in FIG. 7B. It is also possible to use a linear machining electrode having a single generation part or a machining electrode having a triangular surface on the plasma generation part.

The processing electrode 2 has an electrode inclination for inclining the processing electrode 2 so that the surface including the arc of the plasma generating portion of the processing electrode coincides with the normal line of the portion to be processed on the surface of the lens 10 to be processed. Unit 8 is attached.
The electrode tilting unit 8 has a roller and a drive source for rotating the roller. The machining electrode 2 is
It is mounted parallel to the axis of rotation on the outer surface of the roller. The drive source rotates the roller to incline the surface including the arc of the plasma generating portion of the processing electrode 2 by the inclination angle θ required to match the normal line of the portion to be processed of the lens 10 to be processed. (Fig. 5 (b)).

Further, in order to make the plasma generating portion of the electrode 2 to be processed face the portion of the lens 10 to be processed at a desired interval on the work table 1, the lens 10 to be processed is rotated in the xyz direction and rotated. A positioning unit 6 for moving is attached. Work table 1 is
It is made of a conductive material.

Further, the machining electrode 2 and the work table 1 are connected to a power supply system 3 which applies a voltage between the machining electrode 2 and the work table 1 for generating plasma and supplies electric power. .

Electrode tilting unit 8 and positioning unit 6
A control unit 7 for controlling these operations is connected to and.

Further, the chamber 9 is provided with a gas supply system 4 for supplying a reaction gas in the vicinity of the processing electrode 2 and a gas exhaust system 5 for exhausting a gas generated by the reaction between the reaction gas and the lens 2 to be processed. It is installed.

Next, using the lens processing apparatus of FIG.
A method of manufacturing a spherical lens will be described.

First, a spherical lens having a desired radius of curvature is manufactured from a glass block by conventional machining. At this time, as a machining method to be used, the user arbitrarily selects which of the processing steps of grinding, smoothing, and polishing. When a spherical lens that has been subjected to polishing is used as the lens 10 to be processed, the processing apparatus of the present embodiment uniformly removes the work-affected layer of the surface caused by machining from the surface, and a spherical lens having no distortion. It is possible to manufacture When a spherical lens that has been subjected to grinding processing or smoothing is used as the lens to be processed 10, distortion is caused by the processing apparatus according to the present embodiment while removing the work-affected layer caused by grinding processing or smoothing. The surface can be processed smoothly without being processed.

This spherical lens is set on the work table 1 of the lens processing apparatus shown in FIG. Then, the chamber 9 is closed, and the gas exhaust system 5 temporarily depressurizes the chamber 9. After that, the reaction gas is supplied by the gas supply system 4 to set the pressure in the chamber to a predetermined pressure (several hundred torr).
To

The plasma generating portion of the processing electrode 2 is shown in FIG.
As shown in (a), the lens 10 to be processed is brought close to a predetermined distance. A high frequency power is applied to the processing electrode 2 by the power supply system 3. This allows
An arc-shaped local plasma is generated along the plasma generating portion of the processing electrode 2, and the radical of the reaction gas is generated by this plasma.

The control unit 7 includes an arc of the plasma generating unit so that the point 2a of the processing electrode 2 where the plasma generating unit is located moves on the arc 10a which is separated from the lens 10 to be processed by a predetermined gap length. A movement amount for moving the lens 10 to be processed is obtained in the direction perpendicular to the surface and the vertical direction. The movement range of the processing electrode 2 is the lens 1 to be processed.
It is from the end point 10c of 0 to the end point 10d (FIG. 5).
(B)).

At the same time, the control section 7 controls the machining electrode 2 so that the surface of the machining electrode 2 including the arc of the plasma generating section includes the normal line of the surface of the lens 10 to be processed which the plasma generating section faces. The electrode tilting unit 8 is instructed to tilt the tilting amount. The inclination amount is determined based on the normal line of the lens to be processed 19 obtained from the shape data of the lens to be processed 10 before being processed.

When the electrode tilting unit 8 tilts the working electrode 2, the plasma generating portion of the working electrode rotates about the rotation axis of the roller of the electrode tilting unit 8.
The control unit 7 adds the amount of movement of the plasma generation unit caused by the inclination of the processing electrode 2 to the amount of movement described above, and instructs the positioning unit 6 to move the lens 10 to be processed.

Thus, the surface of the machining electrode 2 including the arc of the plasma generating portion is always inclined so as to include the normal line of the lens 10 to be processed, while the plasma generating portion of the processing electrode 2 is
The lens 10 to be processed can be reciprocated with a constant gap length.

By moving the processing electrode 2 in this manner, local plasma generated along the arc of the plasma generation surface of the processing electrode 2 moves along the spherical surface of the lens 10 to be processed. Then, the radicals of the reaction gas generated by the plasma react with the lens 10 to be processed, and the surface of the lens 10 to be processed is processed. The gas generated by the reaction is exhausted by the gas exhaust system 5.

At this time, by adopting the moving method of the processing electrode 2 as described above, it is possible to equalize the time that all points on the lens 10 to be processed are exposed to the plasma generated by the processing electrode 2. The processing amount of all points on the lens 10 to be processed becomes constant. Therefore, the layer of scratches and cracks on the surface of the lens 10 to be processed can be uniformly and rapidly removed while maintaining the curvature of the lens 10 to be processed before being processed by the present processing apparatus.

Further, in the present embodiment, the surface including the arc of the plasma generating portion of the processing electrode 2 is made to coincide with the normal line of the lens 10 to be processed, so that the plasma generating portion of the processing electrode 2 is shown in FIG. ), The plasma generation surface is always located parallel to the tangential plane of the lens 10 to be processed. This makes it possible to make the processing amount of the portion of the lens 10 to be processed facing the plasma generation surface substantially uniform. This is because when one end of the plasma generation surface of the processing electrode 2 is closer to the lens 10 to be processed than the other end, the plasma has an intensity distribution or the plasma does not contact the lens 301 to be processed. It is thought that some parts will occur. 4 (a) and 4 (b) schematically show this phenomenon. As shown in FIGS. 4A and 4B, the plasma region 303 in the portion where the processing electrode 2 is closer to the lens 10 to be processed is more than the plasma region 304 in the portion where the processing electrode 2 is far from the lens 10 to be processed. Plasma intensity is high. The portion in contact with the region 303 having high plasma intensity is the lens 1 to be processed.
Since the machining speed of 0 is high, the depth of the machining mark becomes deep.
Therefore, it becomes difficult to process the lens 10 to be processed into a desired shape with high accuracy. On the other hand, in the present invention, since the plasma generation surface is parallel to the tangential plane of the lens 10 to be processed, it is possible to equalize the processing amount of the portion where the plasma generation surface is opposed, and perform the processing with high accuracy. It can be carried out.

As described above, by using the processing apparatus of the present invention, even if the surface of the object to be processed is a spherical surface such as an optical lens, processing can be performed with high accuracy. Further, even if the lens to be processed is an aspherical lens,
When the amount of aspherical surface is not so large, the aspherical shape before processing can be maintained and an aspherical lens can be manufactured.

In the above embodiment, the machining electrode 2 is used.
Since it reciprocates, streaks may occur in the reciprocating direction. This mainly occurs when the reaction gas is not uniformly supplied to the working electrode. When streaks occur, the processed electrode rotates the processed lens by a predetermined angle each time after passing through the processed lens once,
Since the scratches can be made minute and minute scratches can be randomly scattered on the entire surface of the lens to be processed, an optical lens having no practical problem can be manufactured.

In the processing electrode 2 shown in FIG. 5, the surface (plasma generation surface) facing the lens to be processed has an arc shape along the longitudinal direction, but the plasma generation surface can be spherical. is there. In addition, when unevenness is formed on the plasma generation surface, plasma is easily generated. For example, in the processing electrode shown in FIG. 8, the plasma generation surface has a spherical shape and a groove is formed on the plasma generation surface. Also,
The processed electrode shown in FIGS. 9A and 9B is one in which a rectangular convex portion is provided on the plasma generation surface.

Further, the processing electrode is not limited to one made of one member, but may be made of a plurality of members as shown in FIGS. The electrode shown in FIG. 10 is one in which three electrodes shown in FIG. 5 are arranged at regular intervals and are arranged as one electrode. The processing electrode shown in FIG. 11 is formed by arranging a plurality of pipes so that the cut ends form an arc.

By widening the plasma generating surface as shown in FIGS. 10 and 11, the lens to be processed can be processed in a large area at one time.

Further, as shown in FIG. 12, it is possible to use the wire 301 bent in an arc shape as a processing electrode.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens processing apparatus according to an embodiment of the present invention will be described with reference to FIG. The parts corresponding to those of the processing apparatus according to the embodiment of FIG. 1 are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted.

The chamber 9 has two chambers 9a and 9b.
Is divided into The chamber 9a that houses the lens 10 to be processed and the work table 1 is made of stainless steel and has a diameter of about 600 mm and a height of about 300 mm. Positioning unit 6
Is stored in a chamber 9b independent of the chamber 9a,
The positioning unit 6 was prevented from being exposed to the reaction gas and corroding. Chamber 9b that houses the positioning unit 6
Was made of stainless steel having a diameter of about 1500 mm and a height of 1000 mm. A stainless bellows 9c was connected between the chambers 9a and 9b via a partition wall 9d. The connecting rod 101 connecting the work table 1 and the positioning unit 6 was fixed to the partition wall 9d on the bottom surface of the bellows 9c. Work table 1
Was made of stainless steel with a diameter of 400 mm.

The processing electrode 2 has a thickness of 0.5 mm and a length of 1
It was made of SUS with 50 mm and one side cut with a radius of curvature of 150.4 mm. The gap between the lens to be processed and the electrode 2 was 0.4 mm. Further, not only this working electrode but also a working electrode having a thickness of 1/10 to several mm and a length of 10 to 400 mm can be attached.

The power supply system 3 includes a high frequency power source 31 having a maximum output of 1 kW at 130 MHz and a matching circuit 32.
Composed by and. The matching circuit 32 is provided for impedance matching between the chamber 9a side and the high frequency power supply 31.

The gas supply system 4 is composed of a mass flow controller and a valve for controlling the flow rate of the reaction gas. The reaction gas whose flow rate is controlled by the gas supply system 4 is supplied to the vicinity of the processing electrode 2.

The gas exhaust system 5 is composed of a dry pump, an adsorption device, and a valve. With this configuration, the gas generated by the reaction is sucked by the dry pump and discharged to the outside of the chamber 9a. Further, the produced gas, which is toxic to the human body, is adsorbed by the adsorption device, and then a harmless gas is released to the atmosphere.

The positioning unit 6 for moving the lens 10 to be processed and the work table 1 has the degree of freedom of linear movement and rotation in the three axial directions of X, Y and Z. X and Y are about 150 each
mm and Z had a stroke of 50 mm.

A connecting rod 101 is attached to the work table 1. The partition wall 9d is provided with a through hole. The connecting rod 101 penetrates the through hole in an airtight state and is fixed to the partition wall 9d. Therefore, when the connecting rod 101 is displaced, the partition wall 9d is displaced within the degree of freedom of the bellows 9c. The positioning unit 6 is connected to the end of the connecting rod 101.

Next, the electrode tilting unit 8 will be described with reference to FIG.
Will be described. As shown in FIG. 3, in this embodiment, the electrode 2 is fixed to the roller 81 and the roller 8 is fixed.
The structure in which the shaft 82 fixedly attached to the No. 1 is supported by the support portion 83 is used. The shaft rod 82 was connected to a driving power source 85 installed outside the chamber 9a. The shaft rod 82 is made of ceramics. In this way, by driving the driving power source 85 and rotating the shaft rod 82, the electrode 2 is tilted, and the surface including the arc of the electrode 2 at the arbitrary position of the lens 10 to be processed is processed by the method of the lens 10 to be processed. Can be oriented in a line direction. Further, since the driving power source 85 is installed outside the chamber, it will not be corroded by the reaction gas.

The control unit 7 controls the positioning unit 6 and the driving power source 85 of the electrode tilting unit 8 so that the surface of the electrode 2 including the arc is aligned with the normal line of the lens 10 to be processed and the electrode 2 is covered. The processing lens 10 is relatively scanned.

Using the apparatus having the above construction, φ150 m
m, spherical lens with 100 mm radius of curvature (made of quartz glass)
The creation process of the lens to be processed 10 is performed by the following procedure.

First, the lens to be processed is set on the work table 1. Next, the chamber 9a is closed and the chamber 9
Exhaust the inside of a.

A reaction gas supply system 4 supplies a reaction gas containing He mixed with several percent of SF ₆ to the chamber 9a at a constant flow rate, and a valve keeps the reaction gas at 700 torr.
If the electrode 2 has a geometrical shape as in this embodiment, 100
By applying a high frequency of about W, plasma can be generated only at the tip of the electrode. The radicals of the reaction gas are generated by this plasma. Here, it is considered that the quartz glass and the reaction gas react as follows, and the removal processing proceeds. Note that He does not contribute to the reaction.

SF ₆ → S + 6F ^* 3SiO ₂ + 2SF ₆ → 3SiF ₄ + 3O ₂ + 2S As described above, scanning is performed while aligning the processing electrode 2 with the normal line of the lens 10 to be processed, thereby making a desired scan. A spherical lens can be manufactured.

As described above, according to the present invention, the grinding step,
Since the scratch or crack layer can be uniformly removed from the work surface at a high speed while maintaining the shape accuracy of the smoothing or polishing process, a high-performance optical lens can be formed. The present invention is mainly effective for spherical lenses, but the processed surface may be an aspherical surface unless the aspherical amount is too large. Further, it may be applied to processing of an optical member having a toric surface or processing of an optical member having a flat surface such as a prism or a flat substrate glass.

[0055]

As described above, according to the present invention, it is possible to provide a processing apparatus for processing by the reaction of radicals generated by plasma, which is suitable for processing a curved surface such as an optical lens.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a lens processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a lens processing apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of an electrode tilting unit of the lens processing apparatus of FIG.

4A and 4B are explanatory views showing a state of an electrode 2 and plasma.

5 (a) and 5 (b) are explanatory views showing the operation of the electrodes in the apparatus of FIG.

6 is a perspective view showing an electrode shape of the device of FIG.

FIG. 7 is a cross-sectional view showing the shapes of electrodes that can be used in the lens processing apparatus according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing the shapes of electrodes that can be used in the lens processing apparatus according to the embodiment of the present invention.

FIG. 9A is a top view showing the shape of an electrode that can be used in the lens processing apparatus according to the embodiment of the present invention, and FIG.
Sectional view.

FIG. 10 is a perspective view showing the shapes of electrodes that can be used in the lens processing apparatus according to the embodiment of the present invention.

FIG. 11 is a perspective view showing the shape of an electrode that can be used in the lens processing apparatus according to the embodiment of the present invention.

FIG. 12 is a perspective view showing the shapes of electrodes that can be used in the lens processing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Work table, 2 ... Processing electrode, 3 ...
Power supply system, 4 ... Gas supply system, 5 ...
・ Gas exhaust system, 6 ・ ・ ・ Positioning unit, 7 ・
..Control unit, 8 ... Electrode tilting unit, 9 ... Chamber.

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[Procedure amendment]

[Submission date] February 6, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

[Figure 5]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Teruki Kobayashi Teruyuki Kobayashi 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon (72) Inventor Norio Shibata 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Ceremony Company Nikon

Claims (10)

[Claims] 1. A support part for mounting a work piece, a gas supply part for supplying gas, an electrode for generating local plasma, and a relative part to the work piece. A portion of the electrode facing the workpiece, the portion having a shape corresponding to a desired shape after processing the workpiece in the longitudinal direction. A direction perpendicular to the longitudinal direction while the workpiece facing portion that is a portion facing the workpiece is opposed to the workpiece, and the electrodes are aligned with the normal line of the surface of the workpiece. A processing apparatus, wherein the electrode is moved relative to the workpiece. 2. The machining apparatus according to claim 1, wherein a portion of the electrode facing the workpiece has an arc shape in a longitudinal direction. 3. The processing apparatus according to claim 1, wherein the length of the electrode in the longitudinal direction is longer than the maximum diameter of the workpiece. 4. The moving means includes a surface of the workpiece,
2. The electrode is moved relative to the workpiece so that a surface of a portion of the electrode facing the workpiece is kept at a substantially constant interval. The processing device according to 2 or 3. 5. The work piece is a spherical lens, and a shape of a portion of the electrode facing the work piece is an arc shape, and a radius of curvature of the arc shape is a desired radius of curvature of the spherical lens. The processing apparatus according to claim 1, 2, 3 or 4, wherein a distance between the workpiece and the electrode is added. 6. The moving means causes a workpiece facing portion, which is a portion of the electrode facing the workpiece, to face the workpiece, and causes the electrode to be a normal line of a surface of the workpiece. The processing apparatus according to any one of claims 1 to 5, further comprising an electrode tilting member that tilts the electrode so as to match with. 7. The processing according to claim 6, wherein the electrode tilting member has a rotating body provided with the electrode on an outer peripheral portion, and a rotation driving means for rotating the rotating body by an arbitrary angle. apparatus. 8. The electrode tilting member further comprises control means for instructing the rotation driving means of the amount of rotation of the electrode, wherein the control means uses the shape data of the workpiece to be machined before machining. Find the normal of the part to be processed of the workpiece,
8. The processing apparatus according to claim 7, wherein the rotation driving means is instructed to rotate the rotation angle so that the normal line coincides with a portion of the electrode facing the workpiece. 9. A rotating means for rotating the workpiece relative to the electrode in a state where the electrode and the workpiece are opposed to each other.
The processing apparatus according to any one of items 1 to 8. 10. The processing apparatus according to claim 1, wherein the gas supply unit supplies a reaction gas.