| 摘要 |
<p>Blocks of material moulded in a cavity with opposing ribs which are sufficiently tall to overlap when the mould is closed and slaggered, to contact when the mould is closed. The resulting contact areas between opposing ribs define ventilation slits in objects moulded in the closed cavity. Esp. for moulding packs of expanded polystyrene for contg. perishable goods, e.g. foodstuffs, living creatures, plants, etc. Moulding for ventilation slits avoids a subsequent puncturing operation and the existence of displaced flaps or pieces which may reobscure the openings. The slit position and magnitude is reproducible.</p> |
