| 摘要 |
<p>1,087,143. Sheet forming. UNILEVER Ltd. Nov. 18, 1965 [Nov. 18, 1964], No. 46999/64. Heading B5A. A method of moulding a hollow article comprises the steps of depositing a molten slug of thermoplastic material, e.g. PVC, into a heated die, compressing the slug into a flat preform and subsequently deep drawing or vacuum forming said preform to the final shape whilst it is still held in said die. In one embodiment (see the Figure) a slug from a withdrawable extrusion head 1 is deposited into a die 2 and is compressed into a preform by a plunger 3. The bottom 4 of the die is then lowered, the preform being retained in its position, and vacuum applied to the space below the preform to suck it into contact with the lowered bottom to form the finished article. In a second embodiment (see Figs. 2 and 3, not shown) a slug (13) is deposited into one of several dies mounted upon a rotating table (8) and the table indexed to a station at which a preform is formed by a plunger (12). A second rotating table (9) carrying vacuum moulds (14) is partially superimposed above table (8) so that the preform may be indexed under a mould (14) carried by the table 9 and vacuum formed therein. The article is retained by the mould and the table (9) indexed to bring the mould to an ejection station where the finished article is removed.</p> |
