Patent GB-1251517-A (GB)
IPC: B29C45/06
Filed: 1968-10-31
Abstract: 1,251,517. Clamping injection moulds. L. BERTRANDI. 31 Oct., 1968 [2 Nov., 1967], No. 51765/68. Heading B5A. In an injection process wherein a plurality of annular oil seal defining mould halves 66, 68 are each successively carried to an injection station between an upper ring and lower disc 36 of an intermittently rotated turntable 34, each upper mould half 66 is fixed to a member 52 vertically slidable with lost motion on a rod 40 and each lower mould half to an upwardly displaceable piston rod 62A of a low-pressure cylinder 62 also fixed to the member 52 whereby, immediately prior to the injection station, the mould assembly is closed by the rod 62A and then at the injection station is clamped against a bracket 16 of an upstanding stationary machine frame member 12 with clamping stresses relieved from the turntable 34 as the assembly 52 is displaced along the rod 40 by the higher force of the piston rod 20A of a high-pressure cylinder 20, fixed to member 12, the rod 20A acting on a downward extension of rod 62A. The injection assembly is located on frame member 12 and comprises a cylinder 22 mounted to the lower of rigidly spaced apart members 92, 93 which are slidingly reciprocable, along a pair of rods 91, by a power cylinder 102, whereby the injection nozzle 22A may be engaged with a part 66A of mould half 66. The injection piston comprises a screw which is axially reciprocated by a power cylinder (104), Fig. 2 (not printed), fixed to member 92, and rotated by a drive from motor 96 to a reduction gear-box (100) through which it is slidable. The bracket 16 is protected against impact from the mould assembly by a hardened plate 16B. The upper mould half 66 is provided with a heating plate 58, including electrical heating resistors 58A-58D, and a plate 56 for insulating from an arm 52A of slide 52. The rubber is injected into the annular cavity 70 via a flat mould distribution passage 80 and an annular mould gate 82 of up to 10 to 15 length to thickness ratio, whereby the rubber is heated up to vulcanizing temperatures on forcing therethrough and subsequent, expansion and pressure development on vulcanizing is minimised. After the injection is completed, the rod 22A is retracted and the assembly 52 descends under gravity whereafter the turntable is advanced one step and vulcanization initiated by energizing heaters 58A-58D, with the mould remaining closed under the action of rod 62A. The vulcanization is completed at a position displaced 180 degrees from the injection station and at successive indexed positions thereof, the mould 46 is opened, the seal ejected, the mould cleaned and varnished, and metal inserts may be placed in the mould prior to the injection position. The power cylinders may be hydraulically or pneumatically actuated, or may be replaced by mechanical means, and a chain conveyer may be employed instead of a turntable. Fluid and current are respectively distributed to the cylinders 62 and heating-plates 58 via a stationary shaft 32 on which the turntable hub 35 rotates. The hydraulic circuits are controlled by microswitches actuated by cams 112, 114. It is stated that the moulds may alternatively be clamped at an angle to the axis of the injection cylinder.