Patent GB-1444988-A (GB)
Title: Flat film extrusion die with interchangeable die lips
IPC: B29C48/08
Filed: 1973-10-19
Abstract: 1444988 Interchangeable die lips of flat film die BELOIT CORP 19 Oct 1973 [19 Oct 1972] 48849/73 Heading B5A A flat film extrusion die comprises die halves 11, Fig. 2, which are secured together, by bolts 13, on either side of divider plate 12 to define therewith a pair of outlet passages 20, each supplied by a manifold 19 from an inlet 26, or 29, and respectively connecting to an orifice 52, 70, defined between the divider and a die lip 22, or 23, comprising part of an assembly which is detachably mountable to either of the die halves 11, and includes means for transversely displacing the lip 22, or 23, to vary the depth of the orifice 52, 70. Each die lip 22, or 23 is also stepped at at least two locations, to accommodate at each end of the die at least a pair of internal deckles 50, 51 which are adjustable inwardly of the width of the passages 20. Deckles 91 are also provided, externally and at each end of the orifices 52, 70. The die lips are clamped by bolts, e.g. 34, or 44, Fig. 2, to a downstream face 24 of the die halves 11, and either or both die lips may comprise the lips 22 or 23 of Fig. 2, or the lip 71 of Fig. 4. The die lip 22 is adjustable by sliding movement along the die face 24, effected by screws 40 threadedly engaging, at differential threads, the lip 22 and either a member 37 bolted to the die half 11, of "T" head nuts 45 retained in abutment with member 37 by a retainer bar 46. The die lip 23 is adjustable by flexing movement about a slot 60, effected by screws threadedly engaging, at differential threads, a lip part 65 on one side of the slot, and either the lip part on the other side of the slot, or a "T" head nut 66 retained by a retainer bar 67. The die halves are provided with resistor heaters 16 spaced along each side and controlled from thermocouples 17, and the die lips are provided with resistor heaters 58, 64. In the Fig. 4 embodiment, the die lip 71 is adjustable by sliding movement along a surface 73, effected by a similar differential screw 81 and "T" nut 84. In the Figs. 5 and 6 modification (not shown) of the Fig. 2 lip 23, a lip (123) is provided having adjustment which is effected both by flexing movement in a manner similar to the lip (23) and by sliding movement along the die surface (24) effected by push and pull screws acting on the retainer bar (127) which secures the "T" bolts of the differential thread adjustment for flexing movement. Each external deckle pair 91, Fig. 2, is mounted to a deckle boat 55 for sliding movement in the width direction across the orifices 52, 70, the boat 55 being slidable at in turned flanges 89, along out turned flanges 53, 56 of the die lips. The sliding movement of the boat may be effected by a worm gearing, or by a manually operated rack and pinion 93, 95, Fig. 1. The internal deckles 50, 51 extend from the die through seals 104 and are secured to the boat 55 for simultaneous adjustment therewith by sleeves 105, threadedly engaging the boat 55 or 103, and internal collets 106 which clamp the internal deckles 50, 51. The sleeves 105 may be rotated to release the collets 106, permitting manual adjustment of the deckles 50, 51 independently of each other and of the boat 55. Further internal deckles may be located at the junction of the chambers 19 and passages 20. The deckles 50, 50 may comprise a section which is round, half round, or pointed. The materials extruded by the die may comprise thermoplastic resin, or hot melt adhesive.