Moulding curved plastics printing plates - between cooperating moulds adapted to release the plates first at their edges then at their centres

摘要

Apparatus for moulding curved plastics printing plates comprises an outer female mould half and an inner male mould half comprising a centre section having diverging lateral surfaces and a pair of side sections which cooperate with the lateral surfaces of the centre section. Each side section is provided at its edge with a bar defining a hooked end of the plate. Means are provided to first withdraw the centre section of the male mould relative to its side sections to cause the side sections to move inwardly and pull the edges of the plate inwardly away from the female mould and then to withdraw all sections as a unit to pull the central section of the plate away from the female mould. Continued movement of the centre section causes the bars to release the hooked ends and finally the hooked ends to be pushed from the side sections to completely release the plate. The partial release followed by full release avoids subjecting the surfaces of shear forces and thus the surfaces remain undistorted.