| 摘要 |
<p>In a machine for the simultaneous biaxial drawing of a flat sheet, particularly of polypropylene, the edges of the sheet (1) are gripped by tongs (3) which are driven to the drawing area (9) by diverging threaded spindle (5). At least part of the drawing in the longitudinal direction is achieved simultaneously with part of the lateral drawing by means of an increasing thread of the threaded spindles (5). The increasing thread area (7) is followed, preferably at the end of the threaded spindles (5), by a decreasing thread which causes a longitudinal shrinkage of the sheet already drawn while maintaining a drawing preferably simultaneously in the lateral direction. The shrinkage takes place on 5 to 10% of the length of the spindle at a rate of 10% of the longitudinal drawing previously obtained up to the desired longitudinal drawing of the finished sheet. </p> |
