| 摘要 |
<p>PCT No. PCT/GB93/01259 Sec. 371 Date Feb. 23, 1995 Sec. 102(e) Date Feb. 23, 1995 PCT Filed Jun. 17, 1993 PCT Pub. No. WO94/00278 PCT Pub. Date Jan. 6, 1994An apparatus for shaping perforations of sheet material which comprises a first mold structure at one side of the sheet material and a complementary mold structure at the other side of the sheet material to cooperate with the first mold structure wherein the structures are arranged to be reciprocated and are capable of meeting approximately half way through the sheet material whereby to shape the perforations between them. The apparatus can include a needle so that perforations are simultaneously formed and shaped, or it may be used to shape pre-formed perforations. If a needle is included it may be of the ultrasonic type or it may be heated, e.g. electrically heated. If a needle is used, one of the mold structures may be defined by an appropriate formation on the needle, or the structure may be separate.</p> |
