JP3143651B2 - Manufacturing method of alumina grindstone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an alumina grindstone. More specifically, a method of manufacturing an alumina grindstone used for grinding, cutting, grooving, polishing, etc. of a magnetic disk substrate, a semiconductor substrate such as Si or GaAs, a thin film magnetic hard substrate, a single crystal material, a ceramic glass, etc. About.

[0002]

2. Description of the Related Art At present, with the progress of industries such as optics, electronics and optoelectronics, semiconductor substrates,
The demands on the processing of oxide single crystals, glass, metals, etc. have also become severe, and for grinding, cutting, and grooving, diamond grinders mainly use surface grinders or cylindrical grinders,
Processing mainly with a diamond grinder or the like. Further, there is a grindstone in which plate-like alumina particles are oriented at right angles or parallel to a surface to be processed in order to obtain high efficiency and high quality grinding and polishing. As a method of orienting, there is a method of pressing a mixture of a binder resin and plate-like alumina particles by a doctor blade method, a wet or dry press method or a roll forming method (FIGS. 12 and 13).

However, the production of a grindstone by this method is complicated, and the orientation of plate-like alumina particles is unstable and it is difficult to make it uniform with respect to thick and large-diameter alumina particles. It did not fully exploit the grinding and polishing capabilities it possesses.

[0004]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a method of manufacturing an alumina grindstone which is easy to manufacture and can perform high quality processing.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventor has been able to satisfy all of the above-mentioned problems by rotating a grindstone raw material at a high speed in a grindstone manufacturing process, and it has been difficult to manufacture it until now. The inventor has found that a grinding wheel having a large thickness and a large grinding wheel can also be manufactured, and the present invention has been completed.

That is, the present invention provides: (1) rotating a mixture (abrasive grain concentration: 30 to 90%) of a mixture of a binder resin and plate-like alumina particles having a particle diameter of 0.1 to 50 μm and an aspect ratio of 5 to 20 ; Then, the plate-like alumina particles are oriented by centrifugal force and molded.
(2) a mixture of a binder resin and plate-like alumina particles having a particle diameter of 0.1 to 50 μm and an aspect ratio of 5 to 20 (abrasive grain concentration). (30-90%) is rotated at a high speed to orient the plate-like alumina particles by centrifugal force to form a cylindrical grindstone, and then cut, and further baked at 1000-1300 ° C. A method for producing a porous alumina grindstone is the gist of the invention.

According to the present invention, a mixture of plate-like alumina particles as abrasive grains and a binder resin is rotated at high speed, and the plate-like alumina particles are oriented by centrifugal force to form a grindstone to form a grindstone. It is. When a mixture of abrasive grains and a binder is placed in a mold and the mold is rotated at high speed, plate-like alumina particles having a large specific gravity are oriented in the circumferential direction by centrifugal force. Also,
Centrifugal molding into a wide cylindrical shape, calcination and cutting to the required width,
A firing method is also effective. By controlling the number of rotations, it is also possible to change the centrifugal force and adjust the degree of orientation.

The alumina particles have a particle size of 0.1 to 100 μm.
m, plate-like α-alumina particles having an aspect ratio of 5 to 20, preferably a particle size of 0.5 to 50 μm, and an aspect ratio of 5 to 20.
However, it must be selected according to the requirements of the material of the workpiece and the finished surface. The binder material is a two-component curable urethane resin, a one-component curable urethane resin, an epoxy resin,
Polyamide resins, unsaturated polyester resins, and the like, and thermoplastic resins depending on applications are also possible. In the present invention, when the grinding wheel is in a form in which a grinding layer is formed on a substrate, the substrate supporting the plate-like alumina particle grinding layer can be used in the form of a film, tape, sheet, disk, or the like. These can be composed of polyethylene terephthalate, polyimide, polycarbonate and the like, and those obtained by surface-treating them, and other materials such as synthetic paper and nonwoven fabric.

[0009] According to experiments, when the abrasive grain concentration in the grinding layer of the plate-like alumina grindstone used is less than 30%, the grinding efficiency becomes poor, and when it exceeds 90%, the ratio of the binder resin decreases. During the grinding, the abrasive grains fall off quickly, and the appropriate abrasive grain concentration is in the range of 30 to 90%.

[0010] As an application example, a grinding wheel surface in which plate-like alumina particles are oriented at a right angle is one that brings out the excellent grinding ability of alumina by grinding a workpiece at the edge of the plate-like alumina, and the grinding ability is high. For precision grinding, which requires a large, high-quality finished surface, and a grinding wheel surface with plate-like alumina particles oriented in parallel, polishing the work piece at the edge or / and plane of plate-like alumina Not only is it possible to draw out excellent polishing ability but the processing speed is high, but also a high-quality polished surface can be obtained, which is suitable for polishing and the like that require mirror finishing.

In the method for producing an alumina grindstone of the present invention, the plate-like alumina particles can be sintered by centrifugal molding and then firing at 1000 to 1300 ° C. The sintering further strengthens the alumina grindstone and improves the grinding ability. Also, in this case, the binder resin in the grinding layer is burned off, and the alumina-based grindstone becomes porous.However, this void can retain grinding waste generated at the time of grinding or polishing. It can contribute to prevention. Also, it is desirable that abrasive grains worn out by use be detached from the grinding layer, but the porous structure facilitates the detachment.

The method for producing an alumina grindstone of the present invention will be described with reference to the drawings. 1 to 4 are explanatory views of an apparatus for a method for producing an alumina grindstone of the present invention.

When the centrifugal apparatus shown in FIG. 1 is used, hydrothermal treatment is performed to obtain fine plate-like alumina (α-Al ₂ O ₃ ) powder, which is mixed with a binder resin (binder). The mixture is heated so that the binder resin is in a molten state, and the melt is supplied from a supply unit. During supply, the lower mold is rotating with respect to the upper mold.
According to FIG. 1, a base is provided between the upper mold and the lower mold, but the base does not necessarily have to be arranged as shown in the figure. The melt supplied from the fixed upper mold supply section is
It is supplied to the gap formed between the base and the upper die, and forcibly collides with the inner peripheral surface side of the lower die by centrifugal force due to the rotation of the lower die. By this collision, the alumina powder in the melt is oriented in the vertical direction in the drawing.

Cooling water is supplied to a cooling section provided in the lower mold, which collides with the inner peripheral surface of the lower mold to solidify the oriented alumina powder sequentially with a binder resin as a melt. It is. Next, the case where the centrifugal apparatus of FIG. 2 is used will be described. Basically, it is the same as the centrifugal apparatus shown in FIG. 1, but by using the apparatus shown in FIG. 2, the thickness of the grinding surface of the grindstone can be freely changed according to the supply amount from the nozzle. By using the centrifugal apparatus shown in FIGS. 1 and 2, the width in the vertical direction in the figure can be freely changed by changing the shape of the mold.

For example, a columnar grindstone is manufactured, and polishing can be performed on this surface (curved surface). Further, a grindstone can be prepared by producing a columnar grindstone and slicing it before firing, and using this, grinding and polishing can be performed (FIG. 5). In this case, the shape is determined by the purpose of use and the like. However, in this case, plate-like surfaces of alumina are arranged in a thin portion (thickness direction), and thickness surfaces of alumina are arranged in a thick portion (width direction) (FIG. 6). The sliced whetstone can be used by being appropriately attached to the polishing surface of a number polishing machine.

In the centrifugal molding machine shown in FIGS. 3 and 4, a mixture of plate-like alumina particles and a binder is filled by a gutter penetrated into a mold, and the plate-like particle surface is parallel to the workpiece. Form a whetstone. In FIG. 4, the width of the grindstone for forming the lid attached to the mold as a variable mold can be adjusted. When the centrifugal molding machine shown in FIGS. 1 to 4 is used, the grindstone raw material is preferably filled while rotating the mold.

FIG. 5 is an explanatory view for manufacturing a grindstone by cutting a cylindrical forming grindstone obtained according to the present invention, and FIG.
7 is a schematic diagram illustrating the orientation state of plate-like alumina in a grindstone manufactured by the apparatuses of FIGS. 4 to 4, FIG. 7 is a schematic diagram illustrating a cross section of FIG. 6, and FIGS. FIG. FIG. 10-b is a partially enlarged view of FIG. 10-a, and A shown in these figures indicates each ground layer, in which the plate-like alumina powder is oriented. In the figure, the line in the portion A schematically shows the direction in which the plate-like alumina powder is oriented.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Example 1 A slurry was prepared from a predetermined amount of an aqueous alkali solution prepared by adjusting the particle size of aluminum hydroxide by the Bayer method to a center diameter of 0.7 μm by a ball mill, and the slurry was filled in an autoclave, at a temperature of 600 ° C. and a pressure of 200 atm. For 2 hours. The treated product is washed with water, filtered,
The alumina powder obtained by drying is a fine plate-like alumina (α) having a uniform particle size of 1.0 μm, a thickness of 0.1 μm, a hexagonal crystal form, and a specific crystal plane growing flat.
To obtain a powder -Al ₂ O ₃₎ particles.

The obtained powder was used as abrasive grains, and a thermosetting resin (two-component curable urethane resin) was added thereto as a binder resin (binder) in the same amount, and these were mixed. This was heated to a temperature at which the binder resin was brought into a molten state to obtain a melt. On the other hand, the molding mold of the centrifugal molding machine shown in FIG. 2 was rotated at a high speed of 3200 rpm,
An appropriate amount of this melt is dropped into a molding mold, and centrifugal molding is performed. Next, after drying and intermediate finishing,
It was baked at 0 ° C. to produce a grindstone.

For comparison, plate-like alumina particles having a uniform particle size of 1.0 μm and a thickness of 0.1 μm obtained by the above-mentioned production method were used as abrasive grains, and the mold was left standing without rotating. To make a whetstone.

The end faces of the obtained grindstones (that is,
(The grindstone of the present invention has a plate-like particle surface perpendicular to the workpiece, and the comparative grindstone has a random plate-like particle.)
Was used to grind a cemented carbide having a grinding thickness of 0.5 mm.

As a result, the grinding speed of the grindstone of the present invention was 120% higher than that of the comparative grindstone.
The amount of wear of the grindstone was smaller than that of the comparative grindstone, and the life of the grindstone was long. Furthermore, when the grinding of the cemented carbide was performed using the circumferential surface of each grindstone, when the grindstone of the present invention was used, the polishing speed was slower than that of the comparative grindstone, but the surface roughness was 10 nm. A high quality mirror surface could be obtained.

[0023]

According to the present invention, the grinding wheel is formed by reliably orienting the plate-like alumina particles by centrifugal force, so that the distribution of the plate-like particles is uniform, the sharpness of the grinding wheel is good, and the surface roughness is good.
A polishing wheel can be easily manufactured. In addition, because of the centrifugal molding, the holding force (coupling force) of the grindstone is high, the shape of the grindstone can be maintained with high accuracy, and a thick or large grindstone can be provided at a low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a centrifugal apparatus for carrying out the present invention.

FIG. 2 is an explanatory view of another centrifugal apparatus.

FIG. 3 is an explanatory view of still another centrifugal apparatus.

FIG. 4 is an explanatory view of still another centrifugal apparatus.

FIG. 5 is an explanatory view of a method of manufacturing a grindstone by forming a cylindrical grindstone and cutting the same according to the present invention.

FIG. 6 is a schematic diagram illustrating the orientation of plate-like alumina particles of a grindstone obtained according to the present invention.

FIG. 7 is a schematic view showing a cross section of the grindstone shown in FIG. 6;

FIG. 8 is an explanatory view of a grindstone obtained by the present invention.

FIG. 9 is an explanatory view of another whetstone.

FIG. 10 is an explanatory view of still another grindstone.

FIG. 11 is a flowchart of an embodiment.

FIG. 12 is an explanatory view of manufacturing a grindstone by a doctor blade method.

FIG. 13 is an explanatory view of the above.

Continuation of the front page (72) Inventor Yoshitaka Nagai 1069-2 Examiner, Tsukiyama, Asahi-machi, Shimoshinagawa-gun, Toyama Prefecture Toru Nomura (56) References JP-A-2-30471 (JP, A) JP-A-48-18188 (JP) , B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) B24D 3/00, 3/28

Claims (2)

(57) [Claims] 1. A binder resin having a particle diameter of 0.1 to 50 μm.
m, a mixture with plate-like alumina particles having an aspect ratio of 5 to 20 (abrasive grain concentration: 30 to 90%) is rotated at a high speed to orient the plate-like alumina particles by centrifugal force, and then molded.
A method for producing a porous alumina-based grindstone, characterized by firing at 0 to 1300 ° C. 2. A binder resin having a particle diameter of 0.1 to 50 μm.
m, a mixture with plate-like alumina particles having an aspect ratio of 5 to 20 (abrasive concentration: 30 to 90%) is rotated at high speed to orient the plate-like alumina particles by centrifugal force to form a cylindrical grindstone material. , And firing at 1000 to 1300 ° C.