Vitrified bond grinding wheel and process for producing the same

Abstract

In a vitrified bonded grinding wheel having superabrasive grains 11 such as CBN, diamond or the like bonded with a vitrified bond 12, pores 16 of the vitrified bonded grinding wheel has impregnated thereinto a resin 17 consisting of any resin selected from, e.g., unsaturated polyester, vinyl ester and allyl ester which are in a liquid state at the normal temperature and which have a thermosetting property, and being capable of radical polymerization. Thus, any separation gas or the like is not generated when the impregnated resin is hardened, whereby the strength of the grinding wheel can be enhanced.

Description

TECHNOLOGICAL FIELD[0001]The present invention relates to a vitrified bonded grinding wheel with resign impregnated into pores thereof and a process for producing such a vitrified bonded grinding wheel.BACKGROUND ART[0002]Vitrified bonded grinding wheels in which superabrasive grains such as CBN, diamond or the like are bonded with a vitrified bond are excellent in discharge capability of grinding chips and are sharp in grinding capability for the reason of numerous pores formed between the grains and hence, are advantageous in a respect that grinding can be performed with good surface roughness. In a vitrified bonded grinding wheel of this kind, the provision of much more volume of pore can enhance the sharpness of the grinding wheel, but gives rise to problems that the retaining force of abrasive grains is weakened to become liable to fall during a grinding operation and further that the grinding wheel becomes easy to reach its limit in bending strength.[0003]Japanese unexamined, ...

AI Technical Summary

Benefits of technology

[0008]According to the first invention, by impregnating the resin capable of radical polymerization into the pores of the vitrified bonded grinding wheel, any separation gases or steam is not generated, and thus, the impregnation of the resin can be performed appropriately thereby to contribute to an improvement in the bending strength of the grinding wheel. As a consequence, the falling of abrasive grains during a grinding operation can be suppressed, so that there can be attained an advantage that the wear amount of the grinding wheel can be reduced to elongate the service life of the grinding wheel.

[0010]According to the second invention, since any resin selected from unsaturated polyester, vinyl ester and allyl ester having a thermosetting property and being in a liquid state at the normal temperature is employed as the resin capable of radical polymerization, there can be attained an advantage that any resin selected from unsaturated polyester, vinyl ester and allyl ester can easily be impregnated into the pores of the vitrified bonded grinding wheel at the normal temperature.

[0012]According to the third invention, since the resin being within the range of 60-85 in hardness (Shore D) is employed as the resin capable of radical polymerization, the resin is softer in resin hardness than phenol resin, and hence, the heat generation is suppressed even upon the contact of a workpiece with the impregnated resin during a grinding operation, so that an advantage can be obtained in that it can be realized to prevent grinding burns on the workpiece, depositions on the grinding wheel and the like.

[0014]According to the fourth invention, the grinding wheel substance is formed by filling the mold with the material being a mixture of abrasive grains, bonding agent and the like and then by performing the press forming and burning, the resin capable of radical polymerization is impregnated into the pores of the grinding wheel substance by removing bubbles in a vacuum, with the grinding wheel substance being immersed in the fluid resin capable of radical polymerization, and after the setting of the resin, the resin impregnated grinding wheel substance is adhered to the grinding wheel core. Therefore, it can be reliably and easily realized to impregnate the resin capable of radical polymerization into the pores of the grinding wheel substance. In addition, since no separation gases and steam is generated at the time of setting the impregnated resin, it does not occur that such separation gases or the like cause cavities to be formed in the resin impregnated pores of the grinding wheel substance, so that the resin can be impregnated uniformly into the pores of the grinding wheel substance. Accordingly, an advantage is attained in that there can be easily obtained a vitrified bonded grinding wheel which is capable of enhancing the bending strength of the grinding wheel, of suppressing the failing of abrasive grains during a grinding operation, and of reducing the wear amount of the grinding wheel.

Problems solved by technology

In a vitrified bonded grinding wheel of this kind, the provision of much more volume of pore can enhance the sharpness of the grinding wheel, but gives rise to problems that the retaining force of abrasive grains is weakened to become liable to fall during a grinding operation and further that the grinding wheel becomes easy to reach its limit in bending strength.

However, it was verified as a result of applicant's experiences that one which has phenol resin impregnated into pores of a vitrified grinding wheel is not enhanced sufficiently in the grinding wheel strength (the bending strength of the grinding wheel).

For the reason, it is deemed that one having phenol resin impregnated into the pores of a vitrified grinding wheel is liable to have abrasive grains falling during a grinding operation, is easy to wear and is short in service life.

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