GB1386978A - Covered die closing unit for injection moulding machine - Google Patents

Abstract

1386978 Machinery safety devices K HEHL 5 Sept 1972 [15 Sept 1971 19 April 1972] 41146/72, Heading F2J A guard for enclosing the moving parts of an injection moulding machine comprises two axially movable telescoped covers 23, 17, the first cover 23 of which is slidable relative, i.e. over, cover 17 between an open position and a closed or safe position in which it covers the fixed and movable dies 2, 5 of the machine, and the other cover 17 of which is similarly slidable relative, i.e. under, cover 23 between an open position and a closed position in which it covers the hydraulically actuated die-operating driving toggle linkage 7, 8, 9. The covers 23, 17, when in their normal jointly closed positions (Fig. 1), centrally overlap such that a pair of microswitches 21, 22 on cover 17 engage cam surfaces 25 of a rod 24 on cover 23 (Figs. 1 and 2) whereby the electrical main circuit of the die-closing unit is interrupted whenever one of the two covers is moved out of its closed position (Figs. 3 and 4). Additionally, the cover 23 has an axially projecting link 29 formed with an inclined cam slot 31 which co-operates with a central pin 32 of a shut-off valve unit 30-33 to block the hydraulic circuit of the die-closing unit whenever the die cover 23 is removed from its closed position. The covers 23, 17 are of inverted "U" section, to cover both the top and sides of the relevant working spaces, and are respectively carried by roller pairs 26, 27 and eye brackets 18, 19 on parallel guide rods 13, 14. When the power mechanism linkage is exposed by opening cover 17 and the electrical main circuit is interrupted, a machine setter may still operate the machine for testing and adjustment purposes following a change of dies &c., by a shunt switch in the main circuit which by-passes the electrical safety interlock, the hydraulic circuit remaining functional whilst the cover 23 is closed. A similar arrangement is illustrated in Figs. 9 to 12 (not shown), in which opening and closing of the telescoped covers 23, 17 is effected by a pneumatic piston/cylinder drive mechanism (34-38) arranged therebetween and manually operated by a three-way valve (42). The covers 17 and 23 may be locked in their closed positions, wing nuts 15 securing cover 17 and a lock pin (not shown) through link 29, of cover 23, engaging a bore (49) on die mount 2 (Fig. 11, not shown).