| 摘要 |
<p>A method of heating glass in a hole-punching operation in a piece of glass, e.g. a sheet, comprises the steps of axially aligning a pair of electrodes on opposite sides of a pre-heated piece of glass, supported on a table, in the vicinity of the area to be punched, applying a high frequency electrical pulse current having an on/off ratio much less than unity, e.g. 1: 10 across the electrodes until the glass becomes locally heated to a molten state by the passage of current therethrough. As disclosed, the electrodes are then moved together such that the upper one punches a hole through the molten area of the glass. After punching a shearing tool may be wiped across the surface of the glass to break off any protrusions, the edges of the hole adjacent the broken off protrusion finally being fire-polished.</p> |
