| 摘要 |
<p>733,122. Heating by electric arcs. ANDREWS, A. M. Aug. 7, 1953 [Oct. 21, 1952], No. 21876/53. Class 39 (3). [Also in Group VIII] A method of perforating a sheet. of heat fusible material to form therein an opening of finite size comprises puncturing the sheet, introducing the sheet between a pair of opposing electrodes, producing relative movement between the punctured part of the sheet and the electrodes in a direction parallel to the plane of the sheet, the electrodes being of extended dimensions in the direction of the said relative movement, and producing through the puncture between the electrodes an electric arc discharge which is maintained for a predetermined time which is controlled by the time the puncture is between the electrodes and which is sufficient to heat and fuse the material immediately surrounding the puncture. In the machine shown, a plastic sheet 11 is fed by means of a pair of rollers 12, 13 between a pair of rollers 25, 26 for puncturing the sheet and then between a pair of electrodes 43, 44. The electrode 43 is embedded in a table 10 so that the surface thereof lies flush with the surface of the table while the electrode 44 is mounted on a resilient arm 45 which is releasably clamped by a bar 47 and bolts 48 so that the electrode 44 can be adjusted relatively to the electrode 43 in the direction of travel of the sheet. The electrode 44 has a width greater than the lateral distance between the two outermost rows of perforations. Specification 676,709, [Group VIII], is referred to.</p> |
