| 摘要 |
1,213,059. Sheet forming. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 23 Dec., 1968 [26 Dec., 1967], No. 61043/68. Heading B5A. [Also in Division B3] Hollow articles are drawn from single-layered or laminated plastics, metal, or plastics-metal blanks by apparatus comprising a reciprocable plunger 14 provided at its leading end with an inflatable diaphragm 20 and a co-operating female die 13 provided at its base with a movable plate 15. In one mode of operation, the blank is clamped by piston operated levers 31 over the die and the plate 15 raised into contact with the blank. The plunger is then forwarded into proximity with the blank and the diaphragm inflated through conduit 23 so as to pre-stretch the sheet against the action of the plate 15. Finally the diaphragm is fully or partially deflated and the plunger fully inserted into the die to complete the drawing operation. Fluid may be introduced between the blank and the diaphragm and plate through conduits 25 and 17 in order to control the slippage of the sheet. In alternative arrangements, the diaphragm is inflated simultaneously with, or after, the partial penetration of the plunger into the die, full penetration to complete the forming being effected with the diaphragm partially or fully deflated as before. If desired, undercut articles may be formed using split dies. In an alternative apparatus (see Fig. 6, not shown), the plunger is provided with a cylindrical side diaphragm as well as an end diaphragm and the blank is clamped by a ring carried around the plunger. The ring also serves to cut out a blank from a continuous sheet prior to the drawing operation and carries a cylindrical sleeve which restrains the upper end of the side daphragm during its inflation. |
