Patent GB-845009-A (GB)
Title: Improvements in or relating to apparatus adapted for use in producing coherent moulded articles from powder
IPC: B29C33/00
Filed: 1956-12-20
Abstract: 845,009. Moulding powder into coherentarticles. BRITISH UNITED SHOE MACHINERY CO. Ltd. Dec. 20, 1956 [Dec. 21, 1955], No. 38787/56. Class 87(2). Apparatus for moulding powder into coherent articles comprises a charging hopper for depositing powder in a cavity in a mould assembly provided with heating means and mounted on a conveyor adapted to carry the assembly from the hopper to a pressure applying station, at which means are provided for compressing the powder in the cavity, and locking parts of the mould assembly together, and means at a discharge station for releasing a moulded article from the mould assembly. In apparatus for moulding insoles of synthetic resin, e.g. polyvinyl chloride with plasticizer and pigment, a mould assembly comprises a plate 30, Fig. 1, having a shape corresponding to a pair of insoles joined together, and forming the base of a mould cavity having a wall formed by an apertured plate 32, and is supported on a carriage having side members 40 secured to an endless conveyer 38. The latter is mounted on sprockets 98, Fig. 5, and 100, Fig. 7, and carries the mould assembly beneath a hopper 106 from which the moulding cavity is filled with synthetic resin powder, and thence carries the assembly beneath a doctor blade 108 which levels the material in the cavity. From the blade 108 the mould assembly is carried to a station 110 where an operator manually positions a cover 34 on the plate 32, and thence into an oven enclosed by insulating panels 260 and containing electric heating elements (not shown). Within the oven the cover 34 is depressed at a station 116 to reduce the depth of the mould cavity, and the cover is locked in its depressed condition. On leaving the station 116 the mould assembly passes beneath a roll 314 which is just cleared by the cover 34, unless the latter is not properly depressed so that it engages the roll 314 to operate a microswitch 322 to stop the electric motor driving the conveyor. If the cover 34 is properly depressed the assembly passes out of the oven to a discharge station 104 where means is provided for releasing the cover 34 from the carriage. Feeding the moulding material. The moulding powder is supplied to the hopper 106 from a hopper 120, Fig. 19, in which agitator blades are rotatably oscillated by an electric motor 138. The latter also drives a feed screw which conveys the powder to a blower 126 connected by a pipe 128 to a filter bag 132 through which the air passes whilst the powder falls into the hopper 106. The latter is supported by pairs of arms 152, 156, Fig. 5, pivotally connected to the hopper and to standards 154, and springs 158 acting between the arms 152 and brackets 160 urge the hopper 106 upwardly. Thus the hopper 106 may be lowered by a predetermined weight of powder therein so that an arm 152 operates a microswitch 162 to stop the electric motor 138, whereby the supply of powder to the hopper 106 ceases until the latter may again be lifted by the springs 158 to disengage the arm 152 from the microswitch 162. A screen 166, Fig. 9, covering the outlet of the hopper 106 is sufficiently fine to prevent flow of powder therethrough unless a rotary brush 168 sweeps the inner surface thereof. The brush 168 is driven by chains 186,192,Fig. 5, from an electric motor 198 controlled by a mioroswitch 202. The latter is actuated by a rail on the mould carriage so that the brush is operated only whilst the carriage is passing beneath the hopper 106. The doctor blade 108, is resiliently mounted and vertically adjustable, and lifts excess powder for removal through a suction nozzle 218. Powder on the margins of the plate 32 is removed through suction nozzles 240, and excess powder also falls into a bin 250 to be returned to the hopper 120 via an air blower and filter bag. Pressing the moulding material. The cover 34 is depressed at the station 116 by pressure rollers 268, Fig. 17, carried by a cylinder 264 slidably mounted on a fixed piston 266 and supported by springs 280. The cylinder 264 is moved downwardly by pressure fluid supplied through a tube 286 (not shown), from a tank 290, Fig. 7, upon closing of a solenoid valve 295 when a microswitch 298 is operated by the raising of a rod 302 by a rail 310 on the mould carriage. Whilst the cover 34 is depressed a roll 74 mounted on the carriage engages a fixed cam 78 and rotates to operate a lever 64 to push the mould assembly relatively to the carriage, so that blocks 60 (not shown), on the cover are locked in engagement with gibs 46 (not shown), screwed to the sides 40 of the carriage. Delivering the moulded, article. At the discharge station 104 the cover 34 engages a fixed abutment member (not shown), whilst the carriage continues to move thereby disengaging the gibs from the blocks and releasing the cover. The latter then falls together with the moulded article on to a conveyer belt 118 to be received by an operator. The surfaces of the mould cavity are pre-treated with polytetrafluoroethylene to facilitate release of the moulded article. Specification 679,549 is referred to.