B24B 7/248

Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain for grinding or polishing glass {using reciprocating grinding tools high-frequency reciprocating tools, e.g. magnetically driven}