GB1305630A - - Google Patents

Abstract

1305630 Mixing liquids in proportions VIKING ENG CO Ltd 12 Aug 1971 [19 Sept 1970] 44763/70 Heading B1C [Also in Division Fl] In a method and apparatus for metering and mixing polyurethane foam materials each component (as described, two) is fed from a supply 12, 12a, Fig. 1, to a metering device 11, 11a and then returned to the supply, there being means 14, 14a in each supply line to divert the components to a mixer 13 during part of the return flow. As shown in Fig. 2, an apparatus may consist of metering cylinders 20, 20a having plungers 23, 23a and connected to supply tanks 19, 19a through two-way shuttle valves 18, 18a. The valves are changed over in synchronism by a solenoid-actuated double acting pneumatic cylinder 36 to divert liquid discharged from cylinders 20, 20a to a mixing head 17. The plungers 23, 23a are reciprocated by axially restrained screwed rods 24, 24a, which are rotated in synchronism by a reversible motor 26. The motor shaft 29 is also screwed and carries a non-rotatable but axially free nut 41 which reverses the motor by cooperation with limit switches 40, 40a, the position of which controls the plunger stroke. A limit switch 43 actuates the valve solenoid to change over the valves 18, 18a to supply materials to the mixing head; the valves are then returned to their original positions, after completion of a predetermined number of rotations of the shaft 29, by an adjustable counter 44, the arrangement being such that supply to the mixing head does not take place near the beginning or end of the plunger stroke. The ratio of the components may be altered by changing the gears 25, 25a. There may be a stirrer 39.