Patent GB-1065072-A (GB)
Title: Friction and screw press for the manufacture of ceramic articles
IPC: B30B1/22
Filed: 1964-03-25
Abstract: 1,065,072. Compression moulding machines; screw-presses. U. WALCHHUTTER. March 25, 1964 [March 27, 1963 (2); March 17, 1964], No. 12660/64. Headings B5A and B5F. [Also in Division F2] A compression moulding machine for the production of ceramic articles comprises a vertically reciprocable die carrier 11 which is supported and reciprocated by hydraulic jacks 24, 25 and subjected to the action of a pressscrew 9 during the main compression step, the screw 9 being reciprocated by engagement of one or other of friction discs 6, 7 with a flywheel 8. The sequence of moulding operations is as follows. Filling step.-A matrix 13 is held raised by hydraulic jacks 14, 15, mould bottom plates 16, 16a are held raised level with matrix 13 by an hydraulic jack 17 and die-carrier 11 is held in its uppermost position by jacks 24, 25. In this position already formed articles, e.g. tiles, are ejected from the cavities in matrix 13 by plungers on bottom plate 16. Plates 16, 16a are lowered to the filling position by exhausting jack 17 and subsequent to filling, the plates are lowered on to base 1 by exhausting jack 18. Precompression step.-Die-carrier 11 is lowered in. a controlled manner by jacks 24, 25 to contact matrix 13 which is itself pushed downwardly against the action of jacks 14, 15 which stop or decelerate carrier 11. Preliminary compression takes place. First compression step.-Jack 27, which controls rotation of shaft 5, is activated to cause pressure on die-carrier 11 by screw 9. Further jacks (49), (50), Fig. 3 (not shown), may be provided to act as adjustable shockabsorbers during this downwards movement of the die-carrier. Air exlirusting step.-The direction of rotation of flywheel 8 is reversed to raise screw 9  and although the moulding material is held under pressure, jacks 24, 25 are still acting downwardly, the change in pressure is sufficient to allow the trapped air to escape. Second compression step.-Screw 9 is rotated to force die carrier 11 downwardly further than during the first compression step. After compression -screw 9 is moved upwardly as are plates 16, 16a, matrix 13 and carrier 11 by operation of jacks 17, 18, 14, 15 and 24, 25 respectively. A cleaning device such as a rotating brush may be positioned to clean dies 12 when carrier 11 is in its uppermost position. In the embodiment described, dies 12 do not enter the cavities in matrix 13. Alternatively, dies 12 may be smaller than these cavities and matrix 13 may be held stationary. To prevent overriding of screw 9 upwardly, a lever mechanism 26, 28 is provided which actuates jack 27 to provide a braking action. A lubricating system for screw 9 comprises an oil container (89), Fig. 5 (not shown), a conduit (90) leading to a chamber (77) at the upper end of the screw'and a conduit (91) which leads via non- return valves (93), (94) to a chamber (80) at the lower end of the screw. In operation, assuming chamber (80) to be full, the screw thread (76) decreases the volume of this chamber when screw (9) moves downwardly and oil moves upwardly around thread (76) to chamber (77). If a certain predetermined pressure is exceeded in chamber (80), valve (94) is forced open and oil returns to container (89). When the screw moves upwardly oil is drawn by suction via valve (93) into chamber (80) and oil in chamber (77) is forced back into container (89). Hydraulic systems for operation of the various jacks are also shown and described.