| 摘要 |
1,029,895. Pressure forming sheet material. BROWN MACHINE CO. June 29, 1964 [July 10, 1963], No. 26743/64. Heading B5A. In a pressure forming machine, a sheet 10 of e.g. polystyrene, intermittently advanced by pairs of chains 34, 35, is heated by electric heaters 37 and then moulded by male and female die carriers 12 and 11, which are supported by brackets from lower and upper platens 27 and 21 respectively. The platens 27 and 21 are reciprocated to the moulding position along vertical guideways 19a, mounted on frame members 19, by means of cylinders 23 and 26 respectively, the final closing movement being furnished by piston operated toggle mechanisms (see Figs. 3 and 4, not shown), carried between the respective platen and cross-members 18 and 20 respectively. In operation, the die carrier 11 is first forwarded by cylinder 26 and then by the toggle mechanism, to contact the sheet 10. Platen 27 is then raised until clamping frame 51, carried by platen 27 and biased upwardly by air cylinders 60, 61, co-operates with the sheet (see Fig. 5). Further upward movement of the platen forces plugs 14 into cavities 13, the air being bled off by a suitable valve at the rate of its displacement by the plugs. The toggle mechanism is then actuated to further forward member 50 and clamp it against carrier 11, an airtight seal being formed by sealing ring 53. At this point air under pressure is introduced through pipe 55, and a main vacuum valve 91 (see Fig. 8, not shown) is opened to evacuate cavities 13 thus forming the sheet material against the cavity walls. A pressure sensitive switch 105 (see Fig. 9, not shown) is actuated when the pressure in member 12 has reached a predetermined value to discontinue the pressure at which time another valve is operated to open member 12 to the atmosphere. Air at atmospheric pressure is then introduced into cavities 13, the lower and then the upper platens withdrawn, the sheet indexed forward and the moulding cycle then repeated. |
