| 摘要 |
<p>The system produces a hollow component, a hardening material being sprayed onto a formwork core so as to leave a hole. After the item is hard enough to retain its shape, the core is removed through the hole. The core has two opposite walls movable to and from each other, and one or more sheets whose edges are secured to those of the walls. The latter are moved apart so as to tauten the sheets, after which the material is sprayed on walls and sheets. After hardening, the sheets are released and the walls together again, and finally walls, sheets and actuating mechanism removed through the hole. The sheets can be tautened by gas under pressure, and can be secured to the walls over their entire periphery, forming a closed chamber for filling with the gas.</p> |
