Mfg. elastomeric strip with variable section lip - using two movable, opposing needles on die ring to cut into extrudate lip before vulcanisation

摘要

The process involves (i) extruding the strip (3) at the max cross-section; (ii) cutting grooves in the extrudate lip (12) with two opposing needles (10,11), the operating level of which can be progressively varied by a cam (5); (iii) removing the excess material after extrudate vulcanisation. The appts. includes an adjuster (4) in front of the extruder die ring (1) with metal needles (10,11) inclined relative to one another. The adjuster is spring-tensioned (7) against a plunger (6) in contact with the cam (5) the profile of which corresponds to the change in lip contour height. Raised projections on the cam (5) surface cause the needles (10,11) to make vertical cuts in the lip at the predetermined strip length. USE/ADVANTAGE - For mfg. profiled elastomeric strips of defined length, having a lip with varying cross-section along the length. The cutting action does not cause any further deformation of the unvulcanised lip and a clean cut edge is obtained.