Patent GB-772881-A (GB)
Title: A movable platen press having a toggle mechanism for opening, closing and locking the platens
IPC: B29C45/66
Filed: 1954-12-08
Abstract: 772,881. Casting-machines. MADISON-KIPP CORPORATION. Dec. 8, 1954 [Aug. 11, 1954], No. 35520/54. Class 83 (1). A movable-platen press, e.g. a die-casting machine, having a toggle-mechanism for opening, closing and locking the platens, and operated by a fluid-pressure piston 49, Fig. 1, connected to a block 54, Fig. 3, comprises fixed and movable platens 22, 27, hinge-blocks 31 carried by and transversely - slidable on the movable-platen, front togglelinks 34 and rear toggle or tumbling-links 56 between the hinge-blocks and block 54, cam-slots 58 to move the hingeblocks outwards during closing of the press, and cams 61 to initiate swinging of the frontlinks 34 to a locking position during closing of the press, racks 37 on the front links 34 engaging pinions 41. Rotation of the shafts 39, on which the pinions 41 are fixed, thus has a constant timed relationship to motion of the movable-platen and can be used to control the operation of auxiliary apparatus used in the pressing operation. At the beginning of the closing movement, Fig. 3, the hinge blocks 31 are in their inner positions and the links 56 parallel to the piston-rod 49. The pins 33, by which links 34 are pivoted to blocks 31, extend into cam-slots 58, and as the platen 27 moves forward, the cam-slots move the blocks 31 outwards. The pins 57 which join links 34, 56, extend so that, during the closing of the press, they engage the cams 61 and the links 56 are rotated outwards, causing the rear ends of the links 34 to move outwards to the Fig. 5 position. The racks 37 on the links 34 continue round their rear ends, Fig. 2, so that they continue to rotate the pinions 41 as they move outwards, and the rear ends of the links also have cam-surfaces 38 which engage cams 43 on the shafts 39, the radii of these cams being slightly greater than the pitch radii of the pinions so that the load is transferred to the cam surfaces as the links 56 reach the limit of their motion, the axis of each pin 33 and shaft 39 then lying in a common plane, with the points of the cams in contact. The holes in the lugs 36 of the links 34 are oval so that the load is carried by engagement between the ends of the bosses 32 on blocks 31 and the lugs 36. At this stage an extension 52, Fig. 5, of the piston-rod 49 strikes the block 30, in which the blocks 31 are guided, and thus augments the closing force exerted by the togglemechanism. The ram, shafts 39 and camtrack-plates 59 are fixed on a main cross-head 24 and move bodily with it, when it is adjusted relatively to the fixed-platen 22 by nuts threaded on guide-bars 26, on which the movable-platen 27 slides, whereby differentsized dies may be fitted without altering the setting of the toggle-mechanism. In a modification, Fig. 10, the hinge-blocks 131 incorporate racks 172 which engage pinions 173 on shafts carried by the platen 127. A rod 175, carried by the block 154 to which links 156 (corresponding to links 56 in Figs. 3 and 5) are pivoted, carries racks 174 which engage the pinions 173. The rod 175 has some free movement in the member 154. When the diehalves carried by the platens meet, the continuing forward movement of the racks 174 causes rotation of the pinions 173 in opposite directions, whereby the hinge blocks 131 are moved outwards. At the limit of their movement, the parts then being in the Fig. 10 position, the compression of a spring allows further movement of the piston-rod 149 to strike the guide-block 131 and augment the closing-force.