GB1340200A - Unit for opening and closing moulds and to injection moulding machines incorporating same - Google Patents

Abstract

1340200 Mould closing device MASCHINEN-FABRIK UND GIESSEREI NETSTAL AG 23 Dec 1970 [23 Dec 1969] 61246/70 Heading B5A The movable platen 8 of an injection moulding press is displaceable, along the bars 2, towards and away from a fixed platen 3 over a mould closing distance a, by means of a crank connection 6b, 6a, 5b actuated by a rotary piston drive 7 within a housing 5a, and a mould clamping force is applied to the platen 8 over a distance M1 by a linearly displaceable double acting differential piston 4b which acts on the housing 5a. The piston drives 7, 4b, are of adjustable stroke. The distance M1 is set, e.g. from 0À1 to 0À2 mm., by an electrical contact E1 which is actuated by the platen 8 to cause switching from the hydraulic drive 7 to hydraulic drive of the piston 4b, and when the mould clamping force is released by retracting displacement of the piston 4b over a distance R, a switch E4 is actuated to cause switching from the hydraulic drive of piston 4b to the hydraulic drive 7 to effect mould opening displacement of platen 8. The rest position of housing 5a is determined with respect to a plane X by a pair of opposed springs 13a, 13b, mounted on a positionally adjustable rod 64, which act on a cylindrical member 11 connected to the housing 5a at an arm 9. If closing movement of the platen 8 is obstructed over the distance M1, the crank drive 6b, 6a acts to displace the housing 5a instead of the piston 5b over a distance M2 so that the spring 13a is compressed and one side of a cam 10 carried by the arm 9 halts the drives 4 and 7 by striking a locking valve 14a which also actuates a contact E2 which discontinues the supply of hydraulic fluid to the locking valve 14a. If the mould closing movement of the piston 4b occurs over too great a distance, the housing 5a is displaced around member 5b and consequential damage to the apparatus is avoided by the spring 13b being compressed, over a distance M3, so that cam 10 acts through a locking valve 14b and switch E3 to cause the hydraulic fluid supply to the drives 4 and 7 to be similarly discontinued.