Plastic foam moulding and method and apparatus for its production.

摘要

The component (2) with a cellular structure and a covering layer on at least one face comprises particles of foam (11) esp flexible foam, within a plastic foam and has different densities in specific areas according to requirements. The average density in each part of the component is the same after introducing the foam particle mixture. Densities of elements of the component may be equal after compression of the foam mixture from an initial volume or the densities of the elements may vary depending on the amount of compression in each area. In a prodn process, foam particles, esp from recycled foam, of given size and hardness are mixed with liquid polymer components to coat the surfaces, fed into a closed tool cavity (28) with gas vents and the polymer is reacted and expanded using either temp and pressure or steam. Component (2) densities are maintained within close limits by feeding 3-15%, pref 5-10% more particle and polymer mixture to a balance which releases the precise amount for filling the tool cavity (28) to a conveyor supplying the tool. Process plant includes containers for foam, pelletising appts for prodn of foam particles, a balance with an outlet to a mixer also fed with the liquid polymer binder components. A following intermediate storage tank feeds a further balance connected to a conveyor, eg a blower or a screw with an outlet into a blower feeding the tool cavity (28).