Patent GB-417846-A (GB)
Title: Improvements in and relating to presses for moulding plastic substances
IPC: B28B3/02
Filed: 1933-02-08
Abstract: 417,846. Moulding concrete &c. in stationary mould machines. SMITH, W. H., The Cottage, Imber Court, East Molesey, Surrey. Feb. 8, 1933, No. 3879. [Class 87 (ii).] In a press for moulding plastic substances, particularly concrete, both the pressing and ejection of the pressed material from the mould are effected by toggle mechanism. The pressing may be effected in any direction, but as shown, the mould 5 has a bottom plate 7 connected by rods 8 to a cross-head 6 pivoted to a lever 9 connected to a link 18 having a hooked end 19 which, when the upper plate 16 is depressed into the mould, engages a bail on a lever 66 carrying the upper plate, so that, when so connected, the plate 7, 16 are moved simultaneously towards one another by the toggle 10. After pressing, the plate 16 is raised, and the crosshead 6 is moved upwards to eject the moulded material by the toggle 11. The movements of the toggles are derived from shafts 1, 2, the shaft 1 operating the toggle 10 and being called the compression shaft, and the shaft 2 operating the toggle 11 and being call ed the ejection shaft. As shown in Fig. 1, the shaft 1 is coupled with lost motion to a mutilated pinion 50, and the shaft 2 to a mutilated pinion 51. The pinions are engaged by racks 48, 49 carried by a slide operated by a crank 41 with an adjustable throw and a connecting rod 42. The pinions 50, 51 are operated in sequence by staggering the racks, and flats on the pinions engage flat parts of the racks and keep the pinions stationary at the required times. The thrust of the pinions against the racks is taken by roller bearings 153, 154. The machine is driven by a motor 25 through stepped belt cones 27, 29, the cone 29 being clutched at 86 to a shaft 28 by a coupling which is acted upon by a spring which tends to disengage it. In operation, the material is placed in the mould 5 by hand or, as shown, by a feed box 60, and the clutch is engaged by pushing the handle 104 on the rod 90 which actuates the clutch lever 85. The clutch is held in the engaged position by an abutment engaging in a recess in the rod 90. The pinions are in engagement with the toothless parts of the racks during the initial movement of the crank 41, and are not operated. During this initial movement, a star wheel 37 oscillates an arm on the shaft 1 which agitates the toggle 10 through the arms 12, 14 and thus raises and lowers the plate 7 whereby the material is vibrated prior to pressing. When the vibration is over, the rod 90 is disengaged from its lock by a rotary spring-controlled pawl, and the clutch 86 becomes disengaged. The top of the mould is then strickled by hand or by the feed box 60 ; and the levers 17, 66 carrying the top presser are depressed by hand. The depressing operates the rod 90 by contact with a bell-crank lever, and the clutch 86 is re-engaged. The continued movements of the racks 48, 49 then actuate the pinions 50, 51 in sequence ; the pinion 50 first applying the compression through the shaft 1, arms 12, 14, toggle 10, lever 9 and link 18, and, after the disconnection of the link 18 by cam means, the pinion 51 comes into operation to operate the ejecting toggle 11 by means of the shaft 2 and arms 13, 15. The material is fed to the feed box 60 from a hopper 126 at the bottom of which runs a discharge belt 122 driven by sprockets &c. 119 from a shaft 114 clutched at 113 to the motor shaft. The clutch is operated by a pedal 140 which is also connected by linkage to the feed box 60. Specification 204,414, [Class 87 (ii)], is referred to.