GB1374858A - Process and apparatus for the manufacture of tiles - Google Patents

Abstract

1374858 Moulding plastic substances, &c. INTEROPTIK HANDELSANSTALT 24 Feb 1972 [1 March 1971] 8667/72 Heading B5A [Also in Division F2] Tiles 5 are formed by extrusion of clay, Fig. 1, between a plurality of relatively adjustably spaced die blades 2 of a die 1, into a plurality of vertically juxtaposed layers 3 between which, as the layers move into contact at 8 on leaving the die, a powdered release agent is injected and to the upper and lower exterior surfaces of which is applied impermeable sheets 39, 40, which act to prevent excess evaporation from these surfaces and consequent warpage of the exterior layers; during drying subsequent to the cutting of the layers by a knife 4 to form stacks of juxtaposed tiles 5. The sheets 39, 40 preferably comprise aluminium, oiled paper, or regenerated cellulose and are removed by combustion during baking of the tiles, together with the release agent, e.g. comprising polyvinyl acetate and polyvinyl alcohol powder, which, after drying, acts to temporarily adhere the layers to facilitate transportation. The die 1, Fig. 3 is provided with upper and lower members 12 which are of adjustable inclination, by screws 13, to regulate the lateral flow of the clay between the blades 2. The spacing between the blades 2 is fixed at their downstream ends by steps 15 of the blades 2 locating in notches 14 of the die outlet. The adjustment of the blade spacing, to ensure the same flow between all blades 24-27, is effected at their upstream ends, by engagement of nuts 33-35, Fig. 4, carried by the blades 25-27, on both sides of the central blade 24, with threads 30-32 of concentrically arranged shafts which are simultaneously or independently manually rotatable from the exterior of the die. The shafts on both sides of the central blade 24 are engaged at 36 with the central blade 24, and the threads 30, 31, 32 are of progressively increasing pitch, e.g., in the ratio 1 : 2 : 3 to provide a progressively decreasing adjustment towards the central blade 24 upon simultaneous rotation of the shafts. The nuts 33-35 are mounted within blade notches 37, Fig. 3, by clips (38), Figs. 5 and 6 (not shown), which are of U-section in planes parallel and transverse to the blades.