JPS6288566A - Precision polishing method - Google Patents

Abstract

PURPOSE:To reduce working cost by arranging a polisher provided on the front layer of an electrode board and a workpiece moved relatively to said polisher in polishing liquid to attract and hold abrasives to the surface of the polisher by cataphoresis under the influence of electric field. CONSTITUTION:A polisher provided on the front surface of a turnable electrode board 10 with a fine nap material 9 and a workpiece 8 pressed against the surface of the polisher by predetermined pressure to be relatively moved are arranged in polishing liquid 13 suspending fine abrasive grains 11. An electrode plate 12 is provided in the polishing liquid 13 opposedly to the electrode 10. Under the influence of electric field between both electrodes 10, 12 the fine abrasive grains 11 in the polishing liquid 13 are concentrated on the surface of polisher by the cataphoresis to promote polishing so that extremely high speed working can be carried out without losing advantages of non-contact polishing method and mass productivity improved while a satisfactory finished polished surface can be efficiently attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a precision polishing method for hard and brittle materials such as St wafers, crystalline ferrites, optical glasses, etc.

Conventional technology Conventionally, hard and brittle materials have been processed by grinding with a diamond grindstone or the like, lapping with cast iron or the like using free abrasive grains such as SiC or AI 203, and further polishing methods. is Cu, Sn as polisher.
Polishing is performed using soft metals such as 2 artificial leather, polyurethane, pitch, etc.

However, the above-mentioned polishing and lapping are all destructive processes accompanied by the activation of dislocations and cracks in the material due to a large stress field.

Since processing is based on plastic deformation, the phenomenon accuracy of plastic deformation is the finished surface accuracy. Therefore, a large processing-affected layer such as microcracks remains under the surface formed by brittle fracture.

Further, in the borizing, the brittle fracture may occur on a considerably small scale, or a plastic flow phenomenon may occur due to heat or the like. Therefore, the surface layer of the workpiece becomes a deteriorated layer, and the residual stress becomes considerably large.

For electronic component materials or high-precision optical components, it is necessary to perform polishing without changing the properties of the material itself, and to ensure a highly accurate shape, and processing methods to achieve this are necessary. Various precision polishing methods have been proposed for some time, and some of them have been put into practical use. but,
These polishing methods, which are referred to as non-contact polishing methods, have extremely slow polishing speeds because they are non-contact, and are currently used only for special purposes. In order to improve this low workability, a polishing method using an electromagnetic field has been proposed.

When fine abrasive grains are suspended in a liquid, the particles are naturally charged based on the difference in dielectric constant between the two. When an electrode is inserted into this polishing liquid and a voltage is applied, the particles move toward the electrode depending on the charged state. That is, the particles undergo electrophoresis. A precision polishing method utilizing this phenomenon was investigated (Kurobe, Imanaka et al., Proceedings of the 1986 Spring Conference of the Japan Society of Fine Arts, p.
777).

As a polishing apparatus, two methods shown in FIGS. 4 and 5 have been developed, and are respectively called apparatus I and polishing apparatus.

In the apparatus I shown in FIG. 4, 1 is a machining fluid, 2 is a polisher that rotates while being supported by a lower rotating shaft 2a, 3 is a workpiece, 4 is a brush, and 5 is rotating while being supported by an upper rotating shaft 6a. The workpiece holder 6 is a polishing tank. This device l is
In this method, polishing is performed by immersing the upper rotating shaft covered with the material to be polished and the lower rotating shaft forming the counter electrode in a polishing tank and moving them relative to each other. Polishing is performed in a concentrated manner.

In the apparatus ■ shown in FIG. 5, 5C is a workpiece holder;
7 is an electrode. This device (2) has the workpiece and the electrode set separately in the liquid, and has the feature that a number of workpieces can be immersed in the liquid depending on the size of the polishing tank.

Problems to be Solved by the Invention However, the polishing apparatus described above has the following problems.

In the case of apparatus I and apparatus II, it is necessary to keep the gap between the workpiece and the polisher 2, which is the counter electrode, uniform and at an appropriate distance. If the gap has a slope, the polishing condition may be uneven. Therefore, this polishing method necessarily requires a high-precision and expensive machine. Furthermore, although both Device I and Device II have improved processing speeds compared to conventional non-contact polishing methods,
It is considerably slower than the contact delirium method, and it can be said that it still has problems from the perspective of mass production. Furthermore, in view of the polishing principle, this polishing method has the aspect that it is limited to flat surface polishing. Many mass-produced parts, such as electronic component materials and optical component materials such as lenses, have curved surfaces, and this polishing method does not seem to be very effective for these components.

Means for Solving the Problems In order to solve the above problems, the precision polishing method of the present invention includes:
A polisher with a soft porous material or fine hair material provided on the surface of the electrode plate, and a workpiece that is pressed against the polisher with a predetermined low surface pressure and moves relative to each other are combined using a polishing solution containing an abrasive suspended in a liquid. Further, an electrode plate is provided in the polishing liquid opposite to the electrode plate, and under the influence of an electric field, the polishing agent in the polishing liquid is electrophoretically attracted and concentrated on the surface layer of the polisher. It is held and applied to the surface of the workpiece.

The process consists of an electrode plate with a working polisher on its surface, an electrode plate facing the electrode plate in the polishing liquid around the workpiece, and a voltage applied between these two electrodes. Under the influence of an electric field, the fine abrasive particles in the polishing liquid are concentrated and held on the surface of the polisher by electrophoresis, and in this state are fed to the part where the workpiece is installed and pressed with a predetermined low surface pressure. Since this process acts on the workpiece and polishing progresses, the advantages of the non-contact polishing method are not lost, and processing can be performed at extremely high speeds, improving mass productivity and efficiently achieving a good polished surface.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the processing principle of the present invention. 8 is a workpiece, 9 is a soft fine hair material, 1o is an electrode plate, and the electrode plate 10 and the soft fine hair material 9 constitute a polisher. Still, 11 is a fine abrasive, 12 is an electrode plate,
13 is a polishing liquid. Here, the polisher side is used as an anode, and a DC voltage is applied between it and the electrode plate 12 to provide an electric field. As a result, the fine abrasive particles undergo electrophoresis, and the fine abrasive particles are attracted to and held on the surface of the soft fine hair material 9, and are applied to the workpiece 8 to perform polishing. At this time, the workpiece 8 is pressed against the soft fine hair material 9 with an extremely low load.

FIG. 2 shows an embodiment of a polishing apparatus for carrying out the precision polishing method of the present invention. In FIG. 2, 8 is a workpiece such as Si single crystal or optical glass, 14 is a holder for attaching the workpiece, and 15 is a bearing member that supports the attaching holder 14 and is attached to the attaching holder 14 to rotate. The attachment holder 14 can freely slide in the axial direction with respect to the bearing member 15. This bearing member 16 is driven by a drive motor 16 through a belt 17 at a speed of 10 rpm -50 Orp.
Rotates at m. 1st is a rotary table, driven by a drive motor 19 through a bell) 20 from 10 to 600 rpm
Rotate at m. 21 is an electrode plate made of a material that does not easily cause ionization, such as platinum or stainless steel. This electrode plate 21 and rotary table 18 are insulated via a non-conductive film 22. A soft fine hairy artificial leather 23 was provided on the surface layer of the electrode plate 21. Note that instead of the soft fine hair artificial leather 23, a foamed polyurethane sheet that is a soft porous material can also be used. The polishing liquid 24 is A12Q3.
An abrasive having a diameter of about 0.1 μm, such as Cechi, was suspended in alcohol or water. Reference numeral 26 denotes an electrode that forms an electric field between it and the electrode plate 21. 26 is a brush, 27 is a voltmeter, and 28 is an ammeter, which applies ○ to 5ooV.

However, 29 is a polishing machine body pace, and 30 is a weight that applies a predetermined pressing load to the workpiece.

The operation of the polishing apparatus configured as described above will be explained below.

First, the workpiece 8 is adhesively attached to the attachment holder 14, and pre-processed by grinding or lapping.
Set it on the bearing member 16. At this time, a weight 3Q is set to press the workpiece against the polisher with a predetermined pressure. Furthermore, in order to form an electric field during polishing@24, a predetermined voltage is applied between the electrode plate 21 and the electrode 26 using the electrode plate 21 as an anode. With this electric field, A4°03. Fine abrasive grains such as CeO2 are caused to undergo electrophoresis and are attracted to and held on the surface of the soft, fine hairy artificial leather 23. In this state, the rotary table 18 and the workpiece 8 are rotated at predetermined rotational speeds to perform polishing.

FIG. 3 shows the results of polishing optical glass BK-7 with a diameter of 8 o using this polishing machine. In Fig. 3, 31 is polished without applying voltage, and the pressing pressure is 172.
/cr1i is the rotation speed of the polisher.

The rotational speed of each workpiece was 60 rpm.

B has the same polishing result as A, but the pressing pressure is 35? /c
This is the case for rA. C and D are the cases where a voltage of 130 V was applied between the electrodes under the same conditions as A and B, respectively, and it can be seen that a very large effect was obtained.

As described above, according to this embodiment, R, nax○, α million μ
A good polished surface of less than m can be easily obtained, the polishing speed becomes extremely high, and polishing can be carried out efficiently.

Note that although the above example is about surface polishing,
In the polishing method of the present invention, the physical mechanism in which abrasive grains act on the workpiece during processing is basically the same as that in the contact polishing method, so it can be applied to polishing curved surfaces and the same effects can be obtained. Needless to say.

Effects of the Invention As described above, the present invention comprises a polisher in which a soft porous material or a fine hair material is provided on the surface layer of an electrode plate, and a workpiece that is pressed against the polisher with a predetermined low surface pressure and moves relative to the polisher. is placed in a polishing liquid in which an abrasive is suspended in a liquid,
Furthermore, an electrode plate is provided in this polishing liquid opposite to the electrode plate, and under the influence of an electric field, the polishing agent being polished is attracted and concentrated on the surface of the polisher by electrophoresis, and is held and By applying the abrasive to the surface of the workpiece, the advantages of non-contact polishing methods are not lost, and the effective action of the abrasive on the workpiece significantly increases the polishing speed, improving mass productivity and reducing processing costs. Can be easily reduced. In addition, in the polishing method of the present invention, the physical mechanism by which abrasive grains act on the workpiece during processing is basically the same as that in the contact polishing method, so it can also be applied to polishing curved surfaces.
A similar effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the processing principle of the present invention, and FIG. 2 is a perspective view of a polishing device for performing normal polishing, showing an embodiment of the polishing device using the present invention. 13.24... Polishing liquid, 8... Workpiece, 10°21... Electrode plate, 9,23...
... Soft fine hair material, 12.26 ... Electrode plate, 11 ... Fine abrasive.

Claims (1)

[Claims] A polisher in which a soft porous material or fine hair material is provided on the surface layer of a rotatable electromagnetic disc and a workpiece that is pressed against the surface of the polisher and moves relative to each other with a predetermined low surface pressure are heated using an abrasive. The polisher is placed in a suspended polishing liquid, and further, an electrode plate is provided in this polishing liquid opposite to the electrode plate, and under the influence of an electric field, the polishing agent in the polishing liquid is electrically applied to the surface of the polisher. A precision polishing method characterized by attracting and holding by electrophoresis and applying it to the surface of the workpiece.