| 摘要 |
1300434 Cutting sheets of plastics material; finishing edges P SHEARD and B SHEARD 27 Aug 1971 [3 June 1970] 26690/70 Headings B5A and B5K [Also in Division D1] A web or sheet M of thermoplastic synthetic plastics material is slit longitudinally and the slit edges heat sealed by a heated rotary cutter 22 working against a backing roller 4 over which the web or sheet passes. The web or sheet may be a knitted or woven fabric, e.g. of polypropylene fibres. The cutter 22 comprises an electrically heated disc journalled in the upper limb of a cranked arm 21 pivoted at 20 on a bracket 19 secured on a split block 16 which is secured on a tubular support 13 by a screw clamp 15 so as to be adjustable therealong. The block 16 loosely engages a spline 17 so as to be angularly adjustable through a few degrees. A tension spring 23 pulls the lower limb of the arm 21 down towards a stop 27 on the block 16 but the arm 21 can be adjusted towards and away from the block 16 by a screw 24 acting on the block through a compression spring 25. Engagement of a pin 28 on the bracket 19 in a slot 29 in the arm 21 limits the movement of the arm 21. The temperature of the disc 22 is sensed by a probe carried by a finger 30 mounted by a bar 31 on the arm 21. If the roller 4 stops, a fluid-operated ram 30, Fig. 1, is automatically operated to move the support 13 angularly through a torque arm 32 to lift the disc 22 from the web or sheet M. Pressure is applied to smooth the cut edges whilst they are still soft by a freely rotatable steel roller 34 pressed against the roller 4 by a spring 38. In order to prevent the cut edges joining together again, they are diverted by leading the cut strips around a dividing roller or rollers, by drawing the strips over and/or under one or more smooth surface bars or plates or by providing a dividing plate aligned with the disc 22. Several cutting assemblies may be mounted side-by-side across the support 13 to form a number of parallel slits. |
