GB1358694A - Apparatus for use in the handling of particulate material - Google Patents

Abstract

1358694 Injection or extrusion feed hopper BRITISH UNITED SHOE MACHINERY CO Ltd 22 July 1971 [23 July 1970 16 Sept 1970 19 Feb 1971] 35642/70 44107/70 and 4995/71 Heading B5A [Also in Divisions B1 and B8] Apparatus for feeding particulate material to a plastics injection or extrusion moulding machine comprises a hopper 2 with an inlet 56 for particulate material coupled to a store for such material, an outlet 8 provided with a control valve 50 movable between positions to open and close the outlet and an air entrainment device (20), Fig. 2 (not shown), comprising a Venturi funnel (22) and a nozzle (28) to withdraw air from within the hopper when the valve is closed and thereby draw particulate material from the store into the hopper. If the valve should fail to close, due to material from the previous cycle still being present at the outlet, then the air entrainment device will be unable to lower the pressure in the hopper to such a pressure to effect the drawing of the material into the hopper. The valve 50 is biased into the closed position by a spring 46 and is moved into the open position by a piston and cylinder device 40, the supply of air to which is controlled by a manual switch (not shown) in conjunction with a variable timer to control the period during which the valve is open. Air to the nozzle (28) is also controlled by the switch. In a further embodiment, Fig. 2 (not shown), the valve (140) is urged into its open position by a spring (136) and is moved into its closed position by a piston and cylinder device (130), the supply of air to which is controlled by a switch through a timer (T) and a valve (V3). Mounted on the cylinder (132) for movement therewith is a valve (V1) which when the valve (140) reaches its closed position abuts against an adjustable stop (162) and is opened thereby to supply air to the air entrainment device (150). The control switch may be associated with the injection moulding machine and is operated at certain points in the cycle of operation of the machine. In a further embodiment, Fig. 9 (not shown), the control system includes a valve (V3a) which is spring biased to a position to supply air to the cylinder (232) and via a valve (Via) mounted on the cylinder (232) to a further valve (V2a) which controls the supply of air (M<SP>1</SP>a) to the air entrainment device (250). Air is also supplied through a restrictor (r) and a reservoir (R) to act on the valve (V3a) against the spring and after a time delay, governed by the restrictor, the system is vented to open the valve (240) and stop the air supply to the air entrainment device. A further delay then occurs whilst the air in the reservoir vents to atmosphere through the restrictor (r) before the spring urges the valve back to its original position to recommence the cycle. In a further embodiment, Fig. 10 (not shown), two restrictors (r2b) and (r1b) are used to give independent control over the periods during which the valve (240) is open and closed.