JP2006239796A - Vitreous carbon machining method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vitreous carbon machining method and device, machining vitreous carbon with high accuracy without defect in the machined surface. <P>SOLUTION: The voltage is applied to a tool electrode 204 provided opposite to a workpiece 209 and an electric circuit connected to the workpiece 209 while an electrolyte solution is supplied to the vicinity of a machined part of the workpiece 209 of vitreous carbon. Thus, the workpiece 209 can be electro-chemically machined by feeding the tool electrode 204 into the workpiece 209. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for processing glassy carbon used as a glass molding mold material for optical devices such as aspherical glass lenses.

  As a method for producing an aspheric glass lens used in an optical device such as DSC and DVD, press molding using a cemented carbide mold is used. The cemented carbide mold is used after being subjected to surface treatment after being processed into an arbitrary shape using grinding. However, there is a problem in mass production such that adhesion occurs between the glass material and the cemented carbide mold surface during molding.

  In recent years, application of glassy carbon materials to glass pressing molds has been studied. Glassy carbon has low reactivity with glass, and even in an inert gas atmosphere at high temperatures. It has the characteristic that the property is stable, and is expected to be a mold material for press molding of glass lenses.

  As a conventional glassy carbon processing method, machining such as grinding as shown in FIG. 3 can be cited (for example, see Non-Patent Document 1).

In FIG. 3, a grindstone 101 is attached to a rotatable spindle and can be rotated, and a processing material 102 made of glassy carbon is installed on a rotating stage and can rotate at a constant speed. Further, the spindle for holding the grindstone and the rotary stage are installed on a processing machine stage that can be controlled simultaneously, and can be accurately positioned in an arbitrary direction. In this processing method, the grindstone 101 is processed into an arbitrary shape by cutting into the processing material 102 while rotating.
Proc. Of the Japan Society for Precision Engineering Autumn Conference, 2002 (355 pages)

  However, in the above prior art, since the processing proceeds due to the destruction of the material based on the elastic deformation and plastic deformation of the material, the load on the processing surface is large at the time of processing, and minute defects are formed on the processing surface due to the brittleness of the material. The problem that it is easy to occur arises. Further, the glassy carbon material has a problem that, when compared with the cemented carbide, the elastic modulus of the material after processing is large because the longitudinal elastic modulus is low, and it is difficult to obtain a desired shape accuracy.

  Due to the problems described above, it is difficult to apply the glassy carbon material by machining to high-precision machining for optical devices.

  This invention solves the said conventional subject, and provides the processing method and apparatus of glassy carbon which can process glassy carbon with high precision, without producing a defect in a processing surface. Objective.

  The glassy carbon processing method according to the first invention of the present application is connected to a tool electrode provided facing the workpiece and the workpiece while supplying an electrolyte solution in the vicinity of the processing of the glassy carbon workpiece. The workpiece is electrochemically processed by feeding the tool electrode to the workpiece by applying a voltage to the formed electric circuit.

  According to this processing method, when a voltage is applied between the tool electrode and the glassy carbon that is the workpiece in the electrolyte solution, the given electrical energy causes the ions in the machining fluid to be between the workpiece and the workpiece. A chemical reaction occurs and high-precision processing becomes possible.

  Further, the glassy carbon processing apparatus according to the second invention of the present application holds the supply means for supplying the electrolyte solution to the vicinity of the processing of the glassy carbon workpiece, and the tool electrode so as to be rotationally driven around its axis. A voltage can be applied between the tool electrode and the workpiece, a mandrel, holding means for holding the workpiece, a stage for moving and positioning the workpiece relative to the tool electrode, and An apparatus for processing glassy carbon provided with an electric circuit, comprising a control means for arbitrarily switching a voltage applied while monitoring a current flowing through the electric circuit to a DC voltage and a pulse voltage having an arbitrary time width. It is a feature.

  According to this processing device, it is possible to detect the amount of reaction per unit time by monitoring the current during processing, and it is possible to perform highly accurate processing by changing the energy given according to the reaction state. Become.

  As described above, according to the glassy carbon processing method of the first invention of the present application, since the workpiece is processed by an electrochemical reaction, the load on the material at the time of processing is extremely small, and on the processing surface. Processing with a highly accurate mirror surface is possible without causing brittle fracture.

  Further, according to the glassy carbon processing apparatus of the second invention of the present application, it becomes possible to detect the reaction amount per unit time by monitoring the current during processing, and change the energy given according to the reaction state. By doing so, high-precision machining of the workpiece can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
Embodiment 1 of the processing method of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic diagram of a processing apparatus according to the first embodiment. In FIG. 1, reference numeral 201 denotes a processing apparatus that can move and position in the X-axis direction and the Y-axis direction orthogonal to each other in the horizontal direction. A Z stage 203 that can be moved and positioned in the Z-axis direction perpendicular to the horizontal direction is disposed on 202. On the Z stage 203, a mandrel 205 that can be driven to rotate and holds the tool electrode 204 is held by a V bearing 206, and can be rotated by a motor 208 through an O-ring 207. Further, the processing material 209 is held on the XY stage 202.

  Further, a mandrel 205 that holds the tool electrode 204 and the work material 209 are connected so that a voltage can be applied by a power source 211 via a resistor 210. Further, the processing apparatus 201 is configured to supply the electrolyte solution through the nozzle 212 to the vicinity of the processing point where the tool electrode 204 and the processing material 209 are close to each other.

  In the above configuration, the machining material 209 is supplied with an electrolyte solution from the nozzle 212 disposed in the vicinity of the machining point where the tool electrode 204 and the machining material 209 are close to each other, and the power source 211 connects the tool electrode 204 and the machining material 209. Processing is performed by feeding the tool electrode 204 while rotating it with a motor 208 driven by a voltage applied therebetween.

  At this time, when machining the hole shape of the work material 209, the tool electrode 204 is fed in the Z direction, but the XY stage 202 is driven in synchronization with the feed of the tool electrode 204, and the tool electrode 204 is moved on the work material 209. Any shape can be processed by scanning.

  In the machining method according to the first embodiment, a voltage is applied between the tool electrode 204 and the machining material 209 to apply electrical energy, thereby reacting between ions in the machining fluid and the machining material 209. Occurs and processing proceeds. Since the processing material 209 is processed by an electrochemical reaction, a load during processing is extremely small, and a highly accurate mirror surface can be processed without causing brittle fracture on the surface of the processing material 209.

  Further, when tungsten or titanium is used as the material of the tool electrode 204, the tool material 209 is hardly consumed due to the high corrosion resistance of each material to the electrolyte solution, and the work material 209 can be processed with high accuracy.

  In addition, when deionized water is used as a working fluid, an electrochemical reaction occurs because hydrogen ions and hydroxide ions are generated by water electrolysis only in a very limited range between the tool electrode 204 and the workpiece. The range can be limited, and the processing accuracy can be improved.

  As a specific processing example, a tungsten electrode having a diameter of 50 μm is used as the tool electrode 204, deionized water is used as the electrolyte solution, and 70 V is interposed between the tool electrode 204 and the glassy carbon that is the processing material 209. As a result of applying the voltage and feeding the tool electrode 204 to the work material 209 at a feed rate of 30 μm / sec, a hole with a diameter of 64 μm and an extremely smooth work surface could be machined.

  In machining with a normal rotary tool, microscopic defects are generated on the processed surface due to brittle fracture. However, according to the processing method of the first embodiment, since the processing proceeds by an electrochemical reaction, defects on the processed surface are generated. Highly accurate machining can be realized.

(Embodiment 2)
A second embodiment of the processing method of the present invention will be described with reference to FIGS. Note that the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only differences are described.

  The second embodiment is aimed at higher-precision machining than the conventional technique, and uses a power source capable of generating a pulse voltage as the power source 211. As shown in FIG. 2, the pulse power supply 211 can generate a pulse width 301 of about several tens of nanoseconds with a set voltage 302 at a constant periodic interval 303.

  In the processing method according to the second embodiment, since the processing of the processing material 209 proceeds electrochemically, the reaction amount is determined by the voltage and time applied between the tool electrode 204 and the workpiece 209. Therefore, it is difficult to control the reaction amount in the machining method using a DC power source, and there is a problem that the machining surface of the workpiece 209 is wavy. However, the voltage applied between the tool electrode 204 and the workpiece is pulsed. Thus, the reaction amount per unit time can be reduced, and the processing accuracy can be improved.

  As a specific processing example, using a bottom surface of a cylindrical electrode having a diameter of 250 μm, in plane processing with a unit cut amount of 0.5 μm, a feed pitch of 100 μm, and a tool feed speed of 100 mm / min, Start processing using a DC power supply, change the applied voltage to 70V pulse voltage with a pulse width of 50nsec with a period of 2μsec while monitoring the current flowing through the circuit, and the final value. As a result of the cutting process performed under the above conditions, a flat surface having a mirror surface of 18 nmRz as the processed surface roughness could be processed.

  The glassy carbon processing method and apparatus according to the present invention is a technique that enables glassy carbon to be processed with high accuracy without causing defects on the processed surface, and particularly glass for optical devices such as aspherical glass lenses. It can be applied to the processing of molding mold materials.

Schematic configuration diagram showing a processing apparatus according to Embodiment 1 of the present invention. Schematic showing the voltage waveform of the pulse power supply in Embodiment 2 of the present invention Explanatory drawing of processing method by grinding of conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 201 Processing apparatus 202 XY stage 203 Z stage 204 Tool electrode 205 Mandrel 206 V bearing 207 O-ring 208 Motor 209 Work material 210 Resistance 211 Power supply 212 Nozzle

Claims (5)

The tool is applied by applying a voltage to a tool electrode provided opposite to the workpiece and an electric circuit connected to the workpiece while supplying an electrolyte solution in the vicinity of the processing of the glassy carbon workpiece. A method for processing glassy carbon, wherein the workpiece is processed electrochemically by feeding an electrode to the workpiece. 2. The glassy carbon processing method according to claim 1, wherein the tool electrode is tungsten or titanium. 3. The glassy carbon processing method according to claim 1, wherein the electrolytic solution is deionized water. The glassy carbon processing method according to claim 1, wherein a voltage having an arbitrary pulse width is applied. Supply means for supplying an electrolytic solution to the vicinity of the processing of the glassy carbon workpiece, a mandrel for holding the tool electrode so as to be rotatable about its axis, a holding means for holding the workpiece, and the tool electrode A glassy carbon processing device comprising a stage for moving and positioning a workpiece relative to the workpiece, and an electric circuit capable of applying a voltage between the tool electrode and the workpiece,
An apparatus for processing glassy carbon, comprising control means for arbitrarily switching a voltage to be applied to a DC voltage and a pulse voltage having an arbitrary time width while monitoring a current flowing through the electric circuit.

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