Multiple plug die machine for extruding plastic nettings

摘要

A machine for extruding continuous, integral netting includes a hollow die head adapted to receive plastic material, including resinous plastics and metal alloys, under pressure and a plurality of die plugs, mounted in bearing surfaces in the die head for simultaneous and equi-angular rotation by power means about their longitudinal axes, each plug having at least one extrusion bore one end of which receives plastic material from the die head and the other end terminating at the end of the plug and discharging to the exterior of the die head, said head having a plurality of fixed extrusion passages extending from its hollow interior to its outer surface, each passage being intermittently open to the discharge end of an extrusion bore in a rotating plug. Die plugs 32 (Figs. 1, 2) having extrusion bores 33 are rotated in bearing surfaces 61 formed in the fixed, two part die head 20 having an annular channel 31 for receiving plastic material and provided with fixed extrusion passages 60. A rotary shaft 45 carries a spur gear 44 meshing with pinions 41 to continuously rotate the plugs 32 in unison whereby the discharge ends of the bores 33 and the passages 60 register intermittently to produce a welding of the strands extruded therefrom to form a tubular netting. Alternatively, the plugs may be reciprocated through 180 degrees. Alternatively (Fig. 4), adjacent plugs may be rotated in opposite directions by intermeshing gears 63 and a power driven gear 64. In an embodiment (Figs. 10, 12) for extruding flat netting, die plugs 69 having bores 68 are simultaneously reciprocated by a rack 76 and pinions 75 in the die head 65 provided with fixed extrusion passages 72. Alternatively, (Fig. 13) adjacent plugs 85 may be rotated in opposite directions by inter-meshing gears 86 and a drive gear 87. Other arrangements are described using an increased number of extrusion passages and bores and in which the bores themselves are arranged to register.