公开(公告)号：SE345216B

公开(公告)日：1972-05-23

申请号：SE1687569

申请日：1969-12-08

Applicant: IBM

Inventor： COOK J ,  RALSTON W ,  TOBEN B

IPC: B29C51/42 ,  B29C67/00 ,  C22F1/16 ,  B21D26/00 ,  B21D26/02

Abstract: 1283936 Making hollow-ware; stamping; working at specified temperatures INTERNATIONAL BUSINESS MACHINES CORP 24 Nov 1969 [13 Dec 1968] 57309/69 Headings B3A, B3Q and B3V [Also in Division C7] A method of forming an article from a blank of metal which can be conditioned to exhibit superplastic behaviour, comprises treating a selected portion or portions of the blank before the forming operation to lessen or destroy its super plasticity in the portion or portions treated. As applied to forming a sheet 22 of a superplastic stainless-steel or a 78-22 Zn-Al alloy in a die 20 by differential fluid pressure applied across the sheet, the sheet is clamped over the die by a ring 24 and screws 26. An electric heater 28, 36 is moved on to the sheet which is locally heated to a temperature high enough to destroy or reduce the effect of pretreatment for superplasticity before the heater is switched off and the sheet air-cooled to below the critical temperature for superplasticity (about 530‹ F. for the Zn-Al alloy). The heater is then raised and the whole sheet conditioned by heating to the critical temperature by means not shown before being formed by vacuum below the sheet or pressure applied from above. In the formed article, Fig. 3 (not shown), the thickness of the area (34) where the influence of pre-treatment was destroyed remained unchanged. Overheating and conditioning for superplasticity may be effected before the sheet is applied over the die. In another example, Fig. 6, after clamping the sheet it is first made superplastic by heating with hot air to 520‹ F. and then deflected against the stationary heater 28 1 by pressure within the die 20. The part in contact with the heater is raised above the critical temperature before the sheet is vacuum-formed. One or two pumps 42 1 may supply the pressure and vacuum. Some superplasticity may be allowed to remain in the overheated area by controlling the temperature and time of overheating. Heat-treatment apparatus for conditioning a 78-22 Zn-Al alloy sheet 72 which is to exhibit superplasticity in some areas when reheated to just below the critical temperature of 532‹ F., and less or no superplasticity in other areas, comprises blocks 60, 62 hinged together at 68 and pressed against the sheet by a spring 70. Electric heaters 74, 76 heat the blocks 60, 62 and the sheet 72 to above the critical temperature before they are immersed in a bath 80 of cooling liquid. Fast quenching (room temperature in 5-15 seconds), necessary if the ability to exhibit superplasticity is to be maintained, occurs at those parts of the sheet which are not in contact with the blocks 60, 62. The parts in contact quench more slowly and have a reduced or no tendency to become superplastic when re-heated. The ability to exhibit superplasticity may be reduced or destroyed in selected areas of the Al-Zn alloy sheet by electroplating these areas with copper and holding the sheet at an elevated temperature to diffuse the copper into the sheet.