| 摘要 |
A method of producing a ceramic die for use in superplastic forming includes designing a free standing generally block-shaped ceramic monolithic die base with a bottom surface on which the die rests, and a top surface, opposite to the bottom surface, in which a forming cavity is located and which is surrounded by a contact surface. The forming cavity is shaped like the desired shape of sheet metal parts to be formed by superplastic forming in the die. A die lid is designed having a horizontal cross sectional shape and size approximately equal to the die base, and having a contact surface corresponding in size and contour to the die base contact surface, so that the lid may be placed on the base with the contact surfaces aligning and in contact. A forming cavity model is produced having a shape substantially the same as the part to be formed, and a mold is built having substantially the same internal shape as the intended peripheral shape of the die and having sufficient continuity and strength to contain liquid castable ceramic material. A surface smoothing material and parting agent is applied to the mold and the model, and the model is placed within the mold at a location consistent with the desired shape of the part to be formed. A castable ceramic material for the die base is selected that provides sufficient compressive strength to resist a compressive load exerted by a press to hold the lid on the die against oppositely directed force generated by gas at superplastic forming pressures within the die, and provides sufficient tensile strength, when under pressure of compressive loads exerted by the press to resist internal bursting forces exerted by gas at superplastic forming pressures within the die. The castable ceramic material is mixed with water and is poured into the mold and allowed to set until in substantial thermal equilibrium with ambient temperature. The set die is removed from the mold and is cured at a temperature between approximately 100 DEG -211 DEG F. for a period between approximately three days and ten days. The die is then dried for a period of between two days and four days at temperatures progressing from approximately the curing temperature to approximately 200 DEG F. and back to ambient temperature.
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