| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase edge strength by nearly uniformly imparting specific surface compressive stresses over the entire surface of the sheet glass subjected to a thermal tempering treatment over the entire surface. SOLUTION: The surface compressive stress of 17 to 25kgf/mm<2> is imparted nearly uniformly over the entire surface of the sheet glass 3. More preferably, the surface max. ruggedness of the end face apart 3a of the sheet glass 3 is finished to <=0.05mm and the boundary parts 3c of the end face part 3a and the front and rear plane parts 3b of the sheet glass 3 are finished to the surface max. ruggedness of <=0.007mm. Consequently, the stress concentration to the end edges is averted. The end face part 3a is preferably subjected to the polishing treatment along its longitudinal direction. Namely, the stripes (flaws) accompanying the polishing are formed along the longitudinal direction of the end face apart 3a and the concentration of the thermal destruction force, etc., acting on the plate surface of the sheet glass 3 is averted.</p> |
