JP2000153458A - Flush mounting method and device of grinding wheel surface plate in double-sided work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately perform normal operation without performing running-in work and dummy operation after flush mounting by rotating a correcting grinding wheel by reversing the rotational direction after rotating the correcting grinding wheel in the prescribed direction for a specific time. SOLUTION: While bringing a correcting grinding wheel 7 or a correcting carrier into pressure contact with sandwiching between both upper/lower surface plates, rotating and revolving motion are imparted to the correcting grinding wheel 7 or the correcting carrier to correct/renew the surface of a pellet-like diamond grinding wheel 4. Rotation of the correcting grinding wheel 7 is controlled by driving the outer peripheral teeth provided in an outer peripheral part of a gripping plate 3 by a sun gear 8 and an internal gear 9 of a polishing work machine. Here, rotation of the whole motors for driving the sun gear 8, the internal gear 9, the upper surface plate 1 and the lower surface plate 2 can be simultaneously changed in either reciprocal direction without changing the rotational ratio. After polishing the grinding wheel surface by rotating the correcting grinding wheel 7 in the certain specific direction, the grinding wheel 7 is rotated in the inverse direction of the last time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for correcting a polishing surface of a grindstone surface plate for polishing a surface of glass or ceramics, so-called surface polishing. More specifically, the present invention relates to a correction method using a correction whetstone used for surfacing.

[0002]

2. Description of the Related Art In recent years, glass materials have been used in new applications related to electronic components such as magnetic disk substrates, photomasks, copy mirrors, and liquid crystal glasses, in addition to applications used for building materials, containers, decorative articles, optical lenses, and the like. In particular, in the case of a glass substrate for a magnetic disk, extremely high precision finished surface roughness and shape accuracy are required, and at the same time, improvement in productivity is also required.

Conventionally, in order to obtain a highly accurate shape of a glass material such as a glass substrate, which requires particularly high flatness and parallelism, a general lapping method is conventionally used. Although widely used, in recent years, a grinding method using a grindstone having a high grinding force, for example, a grindstone using diamond or boron nitride (CBN) as an abrasive, has been attracting attention due to its high productivity. It is increasingly being used. In particular, diamond abrasive particles have a strong processing power on glass or ceramics, and the tips of countless abrasive particles fixed on the surface of the grinding stone scratch the surface of the workpiece and promote the removal action,
It is very suitable for a grinding process for adjusting dimensions and shapes.

In order to grind a plate-like glass or ceramics with a grindstone, for example, there is a method of performing single-wafer finishing using a cup-shaped diamond grindstone. However, a disk-shaped glass substrate having a small diameter is efficiently used. To process well,
The shape of the grindstone is pellet-shaped, and it is bonded and arranged on the upper and lower platens of a double-sided processing machine to form a grindstone polishing surface, and multiple glass substrates are sandwiched between them and simultaneously processed while pressing and rotating. (See, for example, Japanese Patent Publication No. Hei 6-22790,
No. 5449). Further, a segmented grinding wheel may be used. As the pellet-shaped diamond grindstone, a metal bond grindstone in which fine diamond grains are fixed with a special alloy is often used, but a resinoid or vitrified grindstone is also used. The glass substrate that has been subjected to the grinding process is thereafter subjected to a polishing process using cerium oxide abrasive grains to finally obtain a precise mirror surface.

As described above, a recent process for processing a glass substrate includes a polishing process using a platen to which a diamond pellet grindstone is attached as a preceding process, and a polishing process using a cerium oxide slurry as a subsequent process. Each step is generally further divided into two or three steps. After removing a thickness of about 0.4 to 0.5 mm in all the steps, a surface roughness (Ra) of about 5 to 10 ° is finally obtained.

[0006] In the case of processing a workpiece such as glass using a diamond pellet-shaped grinding wheel, cylindrical diamond pellets having a diameter of about 10 to 20 mm are almost uniformly adhered to both upper and lower platens of a double-sided processing machine at an appropriate density. This is performed by a double-side processing machine using the grinding and polishing surface formed as described above. A plurality of glass substrates as workpieces are sandwiched between the upper and lower platens via a carrier plate, a processing pressure is applied by the upper platen, and the platen and the glass substrate are rotated while supplying a processing liquid to grind. Perform As the working liquid, an aqueous solution of a surfactant containing no abrasive grains or the like or an aqueous solution of a surfactant containing a small amount of abrasive grains is generally used.

[0007] A diamond grindstone has a strong polishing power and a long lasting property. However, the surface of the diamond grindstone is slightly worn out over a long period of use, and the polishing surface of the platen formed by the entire surface of the diamond pellets. The shape is unevenly changed and deformed, which adversely affects the shape accuracy of the processed workpiece. Therefore, it is common practice to modify the surface of a pellet-shaped diamond grindstone in order to correct the wear of these grindstones and the change in the shape of the polishing surface.

In order to correct the polishing surface, generally, a correction carrier made of a casting is first used, and the correction carrier is placed between the upper and lower whetstone platens, and the surface and the correction whetstone are pressed and rotated to grind the surface. The shape of the working surface that has been worn and deformed by spraying the granular slurry is corrected. Next, the surface of the diamond grindstone is polished by pressing and rotating the platen and the modified grindstone by placing the modified grindstone between the upper and lower platens. As the modified grindstone, for example, a grindstone having relatively high rigidity such as a vitrified grindstone or a resinoid grindstone is often used. When the wear deformation is remarkable, such a two-step correction is necessary,
In the case of mild, it may be done only with the correction whetstone.

The modified diamond grindstone has an extremely strong polishing force because the abrasive grains on the grindstone surface are renewed and the sharp abrasive tips are exposed on the surface. The processing resistance is high, the carrier is severely worn, and the finished surface is rough. For this reason, it is common practice to use a tougher carrier plate than usual for a while after the start-up, to carry out dummy work by so-called crushing, and to perform formal machining after the machine can be operated stably. It is. The number of dummy works required for crushing could be as large as thousands or tens of thousands, and loss in terms of time and energy was extremely large.

The present inventors have conducted intensive studies in order to analyze the above-mentioned phenomenon, that is, a phenomenon in which the polishing resistance is extremely high at the rise after surface exposure, and as a result, have found the following. is there. In other words, when the correction with the correction whetstone is performed in the above-described manner, the diamond abrasive grains exposed on the working surface of the whetstone used for the processing are inclined in the rotation direction of the correction whetstone, and the eyes of the abrasive grains in that direction. They have found that they have a directivity and that they have a strong influence on the grinding resistance.

[0011]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies in view of the above-mentioned problems and the above-mentioned factors in the conventional processing method of glass using a diamond pellet surface plate. The present invention has completed the method and apparatus of the present invention, and an object of the present invention is to provide a method for correcting a grinding wheel surface plate that can be normally operated immediately without performing a running-in operation or a dummy operation after surfacing. Is to do. Still another object of the present invention is to provide an apparatus for performing a correction of a grinding wheel surface plate.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to hold a modified whetstone between upper and lower whetstone platens of a double-sided polishing machine in which a grindstone is attached to both rotatable upper and lower platens to form a polishing surface. In the method of rotating the upper and lower whetstone platen and the correction whetstone while pressing and pressing, and correcting the polishing action surfaces of the upper and lower whetstone platen formed by the whetstone, the correction whetstone is rotated in a predetermined direction for a predetermined time. After that, the rotation direction is reversed, and the rotation is performed. In the method of the present invention, the rotation of the upper and lower stool and the correction wheel in the correction operation is controlled by rotating both the upper and lower stool and the sun wheel gear for driving the correction wheel and all the motors for driving the internal gear, either forward or reverse. A device that incorporates a system that enables automatic switching in the direction is also used.

The essential point of the present invention is that after the correction grindstone is rotated in a predetermined direction for a predetermined time (forward rotation), the rotation direction is reversed (reverse rotation), and thereby the polishing action of the grinding wheel platen used for processing is performed. The object is to correct the inclination of the abrasive grains exposed on the surface in a certain direction, so that the abrasive grains on the working surface do not incline toward one side, and all the abrasive grains stand almost vertically. In other words, by setting the state of the abrasive grains on the working surface of the processing grindstone after the surface correction to such a state having no directivity, the polishing is performed by rotating the workpiece in either direction and performing substantially the same. The polishing resistance value of

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polishing machine used in the present invention has a rotatable surface plate on both upper and lower surfaces, a gripping plate for gripping a workpiece such as glass, and imparts a planetary motion to the gripping plate. It is a so-called double-sided processing machine having a device, while holding and pressing the plate-shaped glass gripped by the gripping plate between the both platens, rotating at least one of both the platen and the gripping plate, Processing is performed. In the present invention, a large number of small pellet-shaped grindstones are arranged on both of the upper and lower stools, and a substantial polishing working surface is formed at the top of the grindstones. FIG. 1 is an explanatory cross-sectional view of a main part of a double-side processing machine used in the present invention. The plate-shaped glass 5 as the workpiece is pressed by the pellet-shaped grindstone 4 arranged on the upper stool 1 and the lower stool 2 while being held by the holding plate 3. The aqueous slurry is supplied from a supply hole 6 provided in the upper platen.

The modification of the polishing surface according to the present invention refers to FIG.
As shown in (1), while the correction whetstone 7 or the correction carrier is sandwiched between the upper and lower platens and pressed, the rotation and revolving motion are given to the correction whetstone 7 or the correction carrier to correct the surface of the pellet-shaped diamond whetstone. The rotation of the correction grindstone 7 is controlled by driving the outer peripheral teeth provided on the outer peripheral portion of the gripping plate 3 by the sun wheel 8 and the internal gear 9 of the polishing machine. That is, by appropriately changing the movement of the sun wheel 8 and the internal gear 9, the rotation direction and the rotation ratio of the correction wheel or the correction carrier can be freely controlled. In the case of the method of the present invention, the rotation of all the motors that drive the sun wheel 8, the internal gear 9, and the upper stool 1 and the lower stool 2,
It is characterized in that it can be simultaneously changed in both forward and reverse directions without changing the rotation ratio.

The object to be processed by the double-sided processing machine according to the present invention is a plate-like glass, for example, a glass substrate for a magnetic disk, a photomask, a copy mirror, and the like. The purpose is. The glass substrate for a magnetic disk referred to herein is a thin circular glass plate having a circular hole at the center and made of soda lime glass (commonly called a blue plate), aluminum silicate-based amorphous glass (commonly called a white plate) or crystallized glass. Refers to a board.

The upper and lower stools, which are formed by attaching a grindstone to form a polishing surface according to the present invention, are formed on the stool surface of an ordinary double-side polishing machine, for example, in the form of segments or pellets, for example, diamond, alumina, Although a grindstone to which abrasive grains such as silicon carbide or boron nitride are fixed is adhered, diamond abrasive grains having particularly high polishing power are often used in processing glass and the like. Examples of the binder include those using metals, resins, ceramics, and the like, and particularly preferably a metal bond grindstone using a metal as a binder is often used. The shape is preferably a pellet. That is, in the present invention, a plurality of metal-bonded pellet-shaped diamond grindstones are attached and used with emphasis on high grinding force and durability. The pellet-shaped whetstone mentioned here is a small column-shaped whetstone having a cross-sectional shape such as a circle, an ellipse, a rhombus, and a rectangle, which is adhered and fixed to a surface of a platen. As a plate-like array shape,
It is arranged so that there is no loss or unevenness of contact with the workpiece during processing, and the total area occupied by the working surface of the grinding wheel is 30 to 7 times the effective working area of each of the upper and lower platens.
It is preferably in the range of 0%. If it is less than 0%, it is easy to cause a drop or a spot in processing, and further dense arrangement is difficult geometrically. The shape of the pellet-shaped grindstone is preferably a columnar shape having a diameter of 7 to 20 mm from the viewpoint of easiness of handling and bonding.

The diamond abrasive grains constituting the pellet-shaped diamond grinding stone according to the present invention include JISR
1000 in the definition of the particle size of the abrasive defined in 6001
Finer than the turn is used. For example, if the glass material is soda lime glass (commonly known as blue plate), 3
A high count of about 000 can be used, but in the case of crystallized glass having a high hardness, a better processing result can be expected by using a glass of about 1,000 to 2,000. Furthermore, as a bonding material for fixing the abrasive grains, metals, resins,
Various materials such as ceramics can be mentioned, but a metal bond grindstone using a metal as a binder is often used.

The modified grindstone used in the present invention is not particularly limited, but is relatively rigid, specifically a resinoid or vitrified grindstone, and is used as an abrasive in accordance with JISR6001. It is preferable to use an alumina-based or silicon-carbide-based finer finer than 400 in the definition of the particle size. As the correction carrier, for example, a cast iron block is used, and a slurry-like liquid in which alumina-based or silicon carbide-based abrasive grains are dispersed in water is supplied to the block.

The essential point of the method for correcting a polishing working surface according to the present invention is that in the step of correcting the shape of the worn and deformed working surface by the action of a correction carrier, and then polishing the surface of the diamond whetstone using the correction whetstone. Another object of the present invention is to prevent a new diamond abrasive grain updated and exposed on the surface of a grinding wheel from having a directionality by controlling a rotation direction of a correction grinding wheel. Specifically, as described above, after the grinding wheel surface is polished by rotating the correction grindstone in a certain direction (this is defined as normal rotation), the grindstone is rotated (reverse rotation) in a direction opposite to the previous direction. It is. That is, the tip of the diamond abrasive grain exposed on the grinding wheel working surface is inclined in a certain direction by the correction operation only in the normal rotation, but the inclination is corrected by the reverse rotation to form a non-directional eye. Therefore, the polishing resistance does not become abnormally high even in the rising polishing immediately after the surface is exposed, and normal processing can be performed.

[0021]

EXAMPLES and COMPARATIVE EXAMPLES The method of the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not particularly limited thereby. The processing machine used in the present embodiment is a 12B-8 type double-sided machine manufactured by Speed Fam Co., Ltd. In this method, a diamond pellet grindstone of Metal Bond # 1500 is used by bonding and arranging the upper and lower platens of the double-sided processing machine. Using this processing machine, routine processing of a 2.5-inch soda lime glass magnetic disk substrate is performed. The processing pressure in this processing is set to a gauge pressure of 200 kg, and 64 workpieces are processed at one time in one processing batch.
After approximately one month of continuous processing, the working reference surface of the platen having an irregular shape was first corrected using a correction carrier made of casting. GC # 2500 using a correction carrier for the target reference plane
While supplying the abrasive grains. Thereafter, using a WA # 800 resinoid-based modified grindstone, the working surface of the grindstone was exposed under the rotation conditions of a lower platen of 10.0 rpm and an upper platen of -3.3 rpm. This state is referred to as state A (Comparative Example of the present invention).
Furthermore, the rotation directions of all the motors were reversed, and the surface was exposed for 5 minutes without changing other conditions. This state is referred to as state B (Example of the present invention).

The frictional resistance of the workpiece in the normal direction and the reverse direction in the above state was measured, and the results shown in Table 1 were obtained.

[0023]

[Table 1]

When the above-mentioned magnetic disk substrate made of soda lime glass was rotated in the positive direction in the state A to perform the processing, the polishing resistance was high and the carrier was damaged. Further, when the polishing was performed by rotating in the opposite direction, the polishing did not proceed at all, though the polishing resistance was low. In the case of state B, there is no difference in the polishing resistance in both the forward and reverse cases. When the actual processing of the magnetic disk substrate made of blue sheet glass was performed, normal processing can be performed from the first batch. 0.2 μm in Ra
The machined surface could be obtained.

[0025]

According to the present invention, the polishing surface of the grindstone surface plate modified by the conventional method has an extreme directionality, and it is necessary to flow a large amount of dummy work before the actual processing can be performed. On the other hand, a grinding wheel surface plate on which a pellet-shaped diamond grinding wheel having a grinding wheel working surface modified by the method of the present invention is attached has no directionality, and normal processing can be performed from the first first batch. It was also confirmed that the method was very economically advantageous.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a main part showing a state in which a work is mounted on a double-sided processing machine.

FIG. 2 is an explanatory sectional view of a main part showing a state in which a correction grindstone is mounted on a double-sided processing machine.

[Explanation of symbols]

1 upper surface plate 2 lower surface plate 3 gripping plate 4
Pellet-shaped whetstone 5 Glass workpiece 6 Slurry supply hole 7
Correction whetstone 8 Sun wheel 9 Internal gear

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Michiaki Tazaki 2647 Hayakawa, Ayase-shi, Kanagawa Prefecture Speed Fam Co., Ltd. F-term (reference) 3C047 AA18 AA21 BB01 EE02 3C058 AA04 AA16 AB01 AB04 BC01 CA06 CB01 DA09

Claims (5)

[Claims] 1. A grinding wheel is attached to upper and lower rotatable surfaces of a double-sided polishing machine in which a grindstone is stuck to upper and lower rotatable surfaces of a rotatable polishing machine. In the method of rotating the surface plate and the correction whetstone, and correcting the polishing action surface of the upper and lower whetstone surface plate composed of the whetstone,
A method of repairing a polishing surface of the grinding wheel surface plate, wherein the grinding wheel is rotated in a predetermined direction for a predetermined time and then rotated in a reverse direction. 2. The method according to claim 1, wherein the modified grinding wheel is a rigid grinding wheel of resinoid or vitrified type.
The method for correcting the polishing surface of the grinding wheel surface plate described in the above item. 3. The modified grinding stone as abrasive grains according to JISR6001
3. The method according to claim 1, wherein the abrasive has a finer number than 400 in the definition of the particle size of the abrasive. 4. The method of claim 1, wherein each of the upper and lower platens is formed by attaching a plurality of pellet-shaped diamond whetstones. . 5. The rotation of both motors for driving both the upper and lower stools and the sun wheel gear and the internal gear for driving the correction grindstone can be switched in both forward and reverse directions. For repairing the polishing surface of a grinding wheel surface plate.