JPH02172672A - Grindstone for grinding ceramics - Google Patents

Abstract

PURPOSE:To grind the ceramics of the material to be ground at high grinding ratio by mixing the abrasive grain of a super hard quality and the ceramics abrasive grain in the larger grain size than that at the specific volume ratio to the respective grindstone whole body and bonding by a bonding material. CONSTITUTION:The grain diameter of an alumina abrasive grain 2 is made larger than the grain diameter of a diamond abrasive grain 1 and the volume ratio of the both 1 and 2 to the whole grindstones is made to be selected according to the working conditions. Thus as the result of the diamond abrasive grain 1 mainly acting as a cutting edge, the grinding ratio becomes higher, the control of the working dimension is facilitated as well, the grinding steak by the diamond abrasive grain 2 is removed by the alumina abrasive grain 1 and the ceramics of the material to be ground can be made in a mirror face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ceramic grinding wheel used for grinding the surface of a ceramic member.

[Prior Art] As is well known, ceramics have extremely high hardness compared to general metal materials. in this way.

In order to grind high-hardness ceramics, 1. As shown in, for example, JP-A-58-82677, JP-A-58-90466, and JP-A-60-85869, ultra-hard abrasives are used. A diamond whetstone is used that has diamond abrasive grains fixed with a binder. In addition, when processing the surface of ceramics into a smooth mirror surface, a regular grinding wheel with ceramic abrasives such as alumina abrasive grains or silicon carbide abrasive grains fixed with a binder is used, and the ceramics are ground together during the grinding process. A mirror surface can be obtained on the surface of the ceramic workpiece by friction through the grinding fluid used.

[Problems to be Solved by the Invention] By the way, when a diamond grindstone is used for grinding ceramics, it is unavoidable that grinding marks remain on the processed surface of the ceramics.

Since ceramics have high hardness but are brittle, there is a risk that cracks will form from the remaining grinding marks, and to prevent this, it is necessary to perform a separate finishing process to remove the grinding marks.

In addition, when using the above-mentioned ordinary grinding wheel to mirror-finish ceramics, since the ordinary grinding wheel uses abrasive grains that have approximately the same hardness as the ceramic work material, as described above, the depth of cut can be reduced. The grinding ratio, which is the ratio between the amount of wear on the grinding wheel and the amount of wear on the grinding wheel, is low, and the amount of wear is large. For this reason, there is a problem in that the outer diameter, which is the grinding surface of the grindstone, changes significantly during machining, making it difficult to control the machining dimensions during machining.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
To provide a grindstone for grinding ceramics which can grind ceramics at a high grinding ratio and process the ceramics to a mirror surface without leaving any grinding marks.

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises ultra-hard abrasive grains,
The grinding wheel is composed of ceramic abrasive grains having a particle size larger than the particle size of the ultra-hard abrasive grains, and a binder that mixes and fixes the ultra-hard abrasive grains and the ceramic abrasive grains at a predetermined volume ratio. Features.

[Function] By setting the particle size as described above, the wear rate of the ultra-hard abrasive grains and the wear rate of the ceramic abrasive grains become approximately the same. In other words, the cutting edge heights of both are always equal. Therefore, during grinding, the cutting edge of ultra-hard abrasive grains cuts the ceramic, and at the same time, the ceramic abrasive grains rub the surface of the ceramic workpiece through the grinding fluid, thereby creating a mirror surface.

[Example] Hereinafter, the present invention will be explained based on illustrated embodiments.

Figure 6 is an explanatory diagram of the structure of a ceramic grinding wheel according to an embodiment of the present invention, in which 1 is a diamond abrasive grain, 2
indicates alumina abrasive grains. 3 is a binder that mixes and fixes a large number of diamond abrasive grains 1 and a large number of alumina abrasive grains 2 substantially evenly. In such a configuration, the particle size of the alumina abrasive grains 2 is larger than the particle size of the diamond abrasive grains. Furthermore, the volume ratio of the diamond abrasive grains to the entire grindstone is approximately 20% to 25%.

The volume ratio of alumina abrasive grains 2 to the entire grinding wheel is 30%.
~40%, that is, 1.2 to 2 times that of diamond abrasive grains. The particle size and volume ratio of the alumina abrasive grains 2 are selected to be appropriate values depending on the surface roughness, grinding efficiency, etc. required of the grindstone.

By the way, in general, when diamond abrasive grains and alumina abrasive grains have the same particle size, alumina abrasive grains have a faster wear rate. For this reason, in this example, the particle size of the alumina abrasive grains 2 was made 1.2 to 2 times larger than the particle size of the diamond abrasive grains 1, so that the wear rates of both were made equal. When ceramics are ground with a grinding wheel having such alumina abrasive grains 2, the cutting edge of the diamond abrasive grains 1 scrapes off the ceramics, and a grinding process occurs between the alumina abrasive grains 2 and the ceramic work material. Friction is generated through the grinding fluid added to the ceramic, giving it a smooth mirror surface. S shown in the figure indicates the working surface of the grindstone, and the working surface of the cutting edge height of the diamond abrasive grain 1 and the working surface of the cutting edge height of the alumina abrasive grain 2 are approximately equal in height, as shown in the diagram. The machining efficiency of grinding is maximized when

In addition, in the Japanese Patent Application Laid-Open No. 58-90466 cited earlier, diamond abrasive grains are used as the main abrasive grains, hot-pressed silicon nitride, which is a ceramic-based abrasive grain, is used as an auxiliary abrasive grain, and both are mixed and fixed with a binder. This example describes a grinding wheel that is similar to the present example.

However, since the grain size of the auxiliary abrasive grains is said to be the same as or smaller than that of the main abrasive grains, they tend to fall off from the bonding material. Therefore, when grinding ceramics with this grinding wheel, it is difficult to There are fewer opportunities for the grains to come into contact with the ceramic work material.

Grinding marks from the main abrasive grains may remain, and a good mirror surface cannot be obtained.

Unlike such conventional grinding wheels, in this example,
The grain size of the alumina abrasive grains is made larger than the grain size of the diamond abrasive grains, and the volume ratio of both to the entire grinding wheel is selected according to the processing conditions.As a result, the diamond abrasive grains mainly act as cutting edges. In addition, the grinding ratio becomes high and the machining dimensions can be easily controlled, and the grinding scratches caused by the diamond abrasive grains are removed by the alumina abrasive grains, making it possible to make the ceramic workpiece material mirror-finished.

In the above embodiments, alumina abrasive grains are used, but silicon carbide abrasive grains, which are made of the same ceramic material, may be used instead.

[Effects of the Invention] As described above, the present invention uses ultra-hard abrasive grains and ceramic-based abrasive grains having a larger particle size.

They are mixed at a predetermined volume ratio to the entire grinding wheel and bonded with a binder, so the ultra-high quality abrasive grains can be used to grind ceramics, which is the work material, at a high grinding ratio, making it easier to control the machining dimensions, and Grinding marks caused by hard abrasive grains can be removed by ceramic abrasive grains, and the ceramic work material can be processed into a mirror surface.

[Brief explanation of the drawing]

The figure is an explanatory diagram of the structure of a grindstone for grinding ceramics according to an embodiment of the present invention. 1...Diamond abrasive grains, 2...Alumina abrasive grains, 3...Binder.

Claims (4)

[Claims] (1) A combination of ultra-hard abrasive grains, ceramic abrasive grains having a particle size larger than the ultra-hard abrasive grains, and mixing and fixing the ultra-hard abrasive grains and the ceramic abrasive grains at a predetermined volume ratio. A grindstone for grinding ceramics characterized by comprising: a grinding agent; (2) The grindstone for ceramic grinding according to claim (1), wherein the volume ratio of the ceramic abrasive grains is 1.2 to 2 times that of the ultrahard abrasive grains. (3) A grindstone for grinding ceramics according to claim (1), wherein the ceramic abrasive grains are alumina abrasive grains. (4) The grindstone for grinding ceramics according to claim (1), wherein the ceramic abrasive grains are silicon carbide abrasive grains.