JPS5871070A - Manufacture of porous elastic grinding wheel - Google Patents

Abstract

PURPOSE:To prepare a grinding wheel in the method of manufacture with very excellent productivity, in preparation of the porous elastic wheel, by using ethylene-acetic vinyl saponified co-polymer for a bonding material. CONSTITUTION:A porous elastic grinding wheel, used for grinding and polishing metal, glass, synthetic resin or leather and the like, can be easily prepared by uniformly mixing an abrasive grain with saponified powder of ethylene-acetic vinyl copolymer, filling to a mold frame, heating under normal, reduced or increased pressure, and sintering in accordance with the normal method of resin sintering. Though sintering temperature is selected in accordance with size, shape, distribution of grain size, proportion of blending and kind of molding of the abrasive grain and saponified particle of ethylene-acetic vinyl copolymer, temperature of 90-150 deg.C is normally preferably. In this way, as compared with a conventional bonded wheel, porous communication is overwhelmingly increased further with a uniform void, and elasticity and radiation of heat are excellent, further productivity can be remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an elastic grindstone. More specifically, the present invention provides a method for producing a porous elastic grindstone with improved quality and extremely high productivity, using saponified wood FIAIi ethylene-vinyl acetate copolymer as a pound material.

Conventionally, so-called elastic grindstones, such as rubber grindstones and resinoid grindstones, have been used for grinding and polishing metals, glass, synthetic resins, leather, etc., in which abrasive grains are solidified using various elastic substances as binders in order to increase their efficiency. has been heavily used. Among them, porous elastic grindstones made of polyvinyl formal resin as a bond material prevent damage to the finished surface and clogging due to chips during grinding and polishing, and prevent overheating by easily dissipating friction heat during grinding and polishing. It is currently the most widely used method as it has extremely excellent effects and also enables polishing of curved surfaces to a certain extent.

However, even though the polyvinyl formal elastic grindstone has the above-mentioned advantages, it also has various drawbacks. Polyvinyl formal elastic grinding wheels are used to process an aqueous solution consisting of polyvinyl alcohol, aldehyde (formalin, acetaldehyde, butyraldehyde, etc.) and mineral acids (e.g. hydrochloric acid and sulfuric acid) by mechanical stirring, carbon dioxide gas, nitrogen gas, air, etc. The abrasive grains are foamed by blowing gas into the mixture, and then heated to a temperature of usually 40 to 70°C for 10 minutes.
It is prepared by holding for ~20 hours to acetalize, thoroughly washing the acetalized product to remove formalin and acid, and drying.

As described above, the manufacturing process of polyvinyl formal elastic grinding wheels is complicated and takes a long time, resulting in low productivity, and the resulting product also has a porous form, i.e., the distribution of external pores is not necessarily uniform. There is a concern that an increase in the air bubble content reduces the mechanical strength of the abrasive and reduces the adhesion between the abrasive grains and the binder.Therefore, this type of whetstone has traditionally been used with a grinding wheel of over 40Of. It is also considered impossible to manufacture a large grindstone.

The present invention aims to provide a method for easily manufacturing an elastic grindstone of excellent quality free from such drawbacks, by mixing a saponified product of ethylene-vinyl acetate copolymer and abrasive grains,
It is characterized by being formed by sintering.

The abrasive grains used in the present invention are powdery or granular natural or synthetic solid substances that have properties such as polishing, grinding, cutting, and polishing. For example, diamond, diamond sand, corundum, emery, garnet, pumice, crystal, iron sand, silica earth, clay, magnetite, alumina, silicon carbide, boron carbide, silicon nitride, boron nitride, metal powder, glass powder, metal oxide. etc. and natural or synthetic polishing agents. These may be used alone or in combination of two or more.

The saponified ethylene-vinyl acetate copolymer used in the present invention is a product obtained by homogeneously or heterogeneously hydrolyzing the acetyl group contained in the ethylene-vinyl acetate copolymer using an alkali or acid as a catalyst. However, a particularly preferred one for the present invention has an ethylene content of 9.
5 to 50 mol%, and the saponification rate of acetyl group is 10% or more. If the ethylene content is too low, the softening point and melting point will be low, the pore retention rate of the porous material will be reduced, and the elastic layer and the dissipation of polishing heat will be poor. On the other hand, if the saponification rate is too low, the adhesion to the abrasive grains may be a little insufficient, making it easy to wear out and lose shape during grinding and polishing. The particle size and particle size distribution of the saponified ethylene-vinyl acetate copolymer can be freely determined depending on the shape of the grinding wheel, the purpose of use, the type of abrasive grains, the relationship with the shape, etc., and the relationship with the porosity of the grinding wheel. There is no particular limit, but preferably 30 to 250 meshes, and the smaller the distribution is, the better.

The porous elastic grindstone of the present invention is prepared by uniformly mixing abrasive grains and saponified ethylene-vinyl acetate copolymer powder, filling a mold, heating under normal pressure, reduced pressure, or pressurization, and performing usual resin sintering. It can be easily obtained by sintering according to the method. Although the sintering temperature depends on the size, shape, particle size distribution, blending ratio, and type of molding of the abrasive grains and saponified ethylene-vinyl acetate copolymer particles, a temperature of 90 to 150°C is usually preferred.

As mentioned above, the porous elastic grindstone of the present invention can be easily prepared in a short time with a simple device, and compared to conventional bonded grindstones, the porous content is overwhelmingly open and the pores are uniform. Because of this, it has excellent elasticity and heat dissipation, and wear and deformation are significantly reduced. Therefore, the productivity is 10 to 20 times higher than that of conventional polyvinyl formal bonded grindstones, and it has become possible to easily prepare large-sized grindstones with a temperature of 400° C. or higher. In addition, in the manufacturing process, there is no use of water, and there is no washing with acid or formalin, so there are great benefits such as energy savings and no pollution (no waste water).

Example 1 Ethylene content 70 mol%, saponification rate of acetyl group 90
% of saponified ethylene-vinyl acetate copolymer 70-1
40 parts by weight of 50 mesh powder and 100 parts by weight of legalized silicon powder as abrasive grains were thoroughly mixed, molded at 200 KFI/d, and sintered at a temperature of 110° C. in coarse-grained silica stone.

A highly elastic product that maintained good porous morphology was obtained. When a copper roll was polished with this grindstone at a circumferential speed of 1500 rrL/mfn, the same effect as that of a polyvinyl formal bond grindstone was obtained, and the roll did not lose its shape.

Example 2 30 parts by weight of S-grade product of SuE IJink DR-55 (saponified ethylene-vinyl acetate copolymer manufactured by Sumitomo Chemical Co., Ltd.), 5 parts by weight of liquid phenol resin, and 100 parts by weight of alundum powder. Mix evenly and weigh 200Kg.
/i and sintered in the same manner as in Example 1, a product with good porous elasticity was obtained.

A polishing test similar to that in Example 1 was conducted using the obtained grindstone, and the same effects as in Example 1 were obtained.

Example 3 15 parts of SM grade product of SuE IJink DR-150 (saponified ethylene-vinyl acetate copolymer manufactured by Sumitomo Chemical Co., Ltd.), 5 parts by weight of liquid phenol resin, 0.5 parts by weight of carbon, CaOO, 5 parts by weight and 10 parts by weight of silicon carbide
0 parts by weight were mixed together, molded at 200 kg/-, and sintered in the same manner as in Example 1 to obtain a product with good porousness and high elasticity.

A polishing test similar to that in Example 1 was conducted using the obtained grindstone, and the same results as in Example 1 were obtained.

Patent applicant: Taoka Chemical Industry Co., Ltd. Patent applicant: Osaka Kongo Seito Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a porous elastic grindstone, which comprises mixing saponified ethylene-vinyl acetate copolymer powder and abrasive grains and sintering the mixture.