Lay flat packages - made of a cellular resin with fold lines of locally crushed material in a single unit

摘要

Packages comprising a series of panels made of a cellular material, such as expanded polystyrene, sheet are integrally linked by hinges of crushed structure. Pref. the hinge zones are made by pre-expanding the material in an oversize mould cavity contg. inserts comprising a ramped or stepped profile which almost bridges the mould cavity when the mould is closed. Alt. the hinge zones may be crushed to an adjustable degree after mould closure by mobile blades intersecting the cavity. Allows packs to be made in one piece from materials thick enough to offer e.g. stiffness impact resistance or to permit tongue and groove alignment or assembly without buckling due to excess thickness at the fold zones.