| 摘要 |
P-2663 PROCESS AND APPARATUS FOR STRETCHING A TUBULARLY-FORMED SHEET OF A THERMOPLASTIC MATERIAL AND THE PRODUCT PRODUCED THEREBY . There is described in a preferred embodiment of the present invention, a process and apparatus for biaxially stretching a tubularly-formed sheet of thermoplastic material in a first station and a plurality of second stations wherein the first and second stations are provided with sets of rolls having generally sinosoidallyshaped grooves perpendicular and parallel, respectively, to the axis of each set of rolls to produce hags of improved strip tensile breaking strength. |
