This invention relates to a grinding wheel (generally inclusive of grindstone), more especially to a resinoid grinding wheel, i.e., grinding wheel in which a resinoid bond (resinous bond) is employed.
A bond used in a grinding wheel generally includes vitrified, resinoid, metal and the like. The resinoid includes resins such as phenol resin, epoxy resin, urethane resin, melamine resin, PVA (polyvinyl alcohol) resin, acrylic resin and the like. These are used depending on workpiece to be ground.
The main reason why the resinoid is used for the bond of a grinding wheel is that it can reduce the load applied on abrasive grains in the course of grinding by its low elastic modulus. By this reason, the resinoid is much used for grinding which requires comparatively high load as compared with other bonds.
Among these resinoid bonds, an epoxy resin is most used especially for grinding with a large stock removal, since its elastic modulus is lower than other resinoid bonds.
However, conventional resinoid grinding wheel has a problem that grinding resistance increases in the course of grinding and grinding burn occurs finally.
In order to solve this problem, there have been proposed such methods for changing the resinoid grinding wheel to have a rough structure by adding thereto an inorganic filler having a very low strength (or hardness) such as talc, mica and the like or inorganic spherical hollow material such as alumina bubble, glass balloon or the like.
However, these methods involve a problem that essential properties of the resinoid grinding wheel become deteriorated by applying these methods. Explaining more in detail, a property of the low elastic modulus that the resinoid grinding wheel essentially has becomes hardly exhibited, and the inorganic filler sometimes prevents grinding. As such, application of the conventional methods raises another problems. As a matter of course, any conventional method has not hitherto provided a perfect solution.
Accordingly, it is an essential object of the present invention to provide a novel resinoid grinding wheel which provides a complete solution to the above described problems that the conventional resinoid grinding wheel has.
In other words, the object of the present invention is directed to provide a resinoid grinding wheel which has low grinding resistance and capable of providing ground materials excellent in ground surface quality without causing grinding burn in the course of grinding while maintaining essential properties of the resinoid grinding wheel such as low elastic modulus and strong force for holding abrasive grains.
Other objects of the present invention will become apparent from the entire disclosure herein.
A resinoid grinding wheel of the present invention includes abrasive grains and filler dispersed in a bond. The filler includes an effective amount of organic hollow material having diameters sufficient for obtaining ground materials excellent in ground surface quality. The bond comprises a cured resin which is produced by curing a liquid resin.
The cured resin can be selected from one or more of cured epoxy resin, cured phenol resin, cured acrylic resin and cured urethane resin.
The average diameter of the organic hollow material may be in a range of 10 to 300 xcexcm.
The organic hollow material preferably includes one or more of acrylic resins and polyvinylidene chloride-based resins.
The wall thickness of the organic hollow material may be not more than 5 xcexcm.
The true specific gravity of the organic hollow material may range from 0.01 to 0.1.
The ratio U/B by volume of the organic hollow material U to the bond B may be in a range of 5/100 to 80/100.
The resinoid grinding wheel of the present invention may includes pores as its void in addition to the organic hollow-material. In this case, the ratio K/B by volume of the pores K to the bond B preferably ranges from 5/100 to 350/100.