Patent GB-710433-A (GB)
Title: Improvements in and relating to apparatus for forming molded plastic articles with cavities
IPC: B28B7/00
Filed: 1951-10-10
Abstract: 710,433. Moulding concrete &c. blocks. ROSS, C. R. Oct. 10, 1951 [Oct 12, 1950], No. 23599/51. Class 87 (2) Apparatus for making articles from plastic material, such as concrete, comprises a mould having at least one pair of opposite walls rigidly fixed in relation to each other into which mould plastic material for the article may be poured, a withdrawable plate forming a wall of the mould and having at least one hole therein, a header positioned abreast the plate parallel thereto, a pin or pins secured to the header for the or cach plate hole extending towards the plate, and neans for moving the header towards or away from the plate to move each header pin through a corresponding plate hole into or out of the mould. In one embodiment, Figs. 2 and 3. the block is moulded between a bottom pallet board 20 and a vertically movable head 22, the boundaries of the mould being formed by end plates 25 projecting from the head 22 and headers 28 which are movable horizontally into position to form the sides of the mould. The headers may be moved by hydraulic or pneumatic means, as may also the head 22 through a connection 32 which is tubular and through which concrete may be poured into the mould. Core pins 35 project into the mould from each of the headers 28. passing freely through plates 4:3 interposed between the headers and the mould, Fig. 4. After the concrete 10 has been poured and pressed in the mould the headers and core pins are withdrawn but the plates 43 remain sticking against the side of the block and prevent dislodged particles of concrete from falling into the newly-formed holes. Preferably the plates 43 have bolts 48 projecting from them and passing through, the headers 28, of such a length that the headers move away from the mould without disturbing the plates 43 until they engage the bolt heads 51, when the plates are withdrawn. the core pins being then clear of the holes. Preferably also springs 54 may be provided on the bolts 48. housed in wells formed in the headers, for pressing the plates 43 against the surfaces of the moulded block while the core pins are being withdrawn. The core pins may be tapered to give the outer end of the holes a funnel shape, as shown, and the plates 43 may have protuberances on their inner sides surrounding the holes for the core pins to form corresponding recesses in the cast block. In another embodiment, Fig. 9, the mould 71 is divided into compartments to form blocks 10 on edge and the holes are formed by core pins 75 projecting downwards from a top header 66 and by core pins 85 projecting Upwards from a bottom header 84, which may be raised and lowered by hydraulic cylinders 89, The plunger or header 66 has projections which fit into the mould compartments as it moves downwards. A pallet 65 forming the bottom of the mould has holes through which the core pins pass freely, as in the case of the plate 43 in the first embodiment. The pallet may be moved along rails 67 against a retractable stop 68, whereby it may be accurately positioned so that the core pins 75, 85 are exactly opposite. A plate 81 is also positioned below and in contact with the pallet, 65, with slots 82 to provide clearance for the core pins, and this plate is vibrated, e.g. by cams 83. Vibrating means may be provided in the header 66, which may also have a plate corresponding to the plate 43, though it is stated that the holes formed in the top of the block are not deformed by loose particles when the upper header is raised.