| 摘要 |
925,422. Stamping; making cylinders; sizing and restoring shape of articles. AEROJET-GENERAL CORPORATION. July 12, 1960 [July 27, 1959], No. 24303/60. Classes 83 (2) and 83 (4). A method of fabricating a metal member includes the steps of arranging a metal blank so that it faces the contoured surface of a die, submerging the blank and die in a fluid body and detonating an explosive charge submerged in the fluid body. Apparatus for carrying out the method comprises a frame 4 mounted on supports 6 and carrying a die 8 embedded in concrete or lead 12. A steel blank 20 is clamped to the die in a fluid-tight manner by a hold-down ring 24. An explosive charge 32 is suspended above the blank on a member 34 attached to the frame 4. The die cavity 9 is evacuated through a vacuum line 10 and the apparatus is placed on the bottom of a tank 16 which is set in the ground and filled with water 14. The explosive charge is then fired to deform the blanks into the die cavity. A watersoluble lubricant is used on the die to assist the cupping operation and to facilitate removal of the formed blank from the die. The products of detonation form an oscillating gas bubble which aids in the cupping operation by producing a hammering effect on the blank. In another embodiment a cylinder 42 is sized by placing it in a split die 38. The air in the cavity surrounding the cylinder and the die is evacuated through a pipe 45, a string explosive charge 46 is suspended in the cylinder which is then filled with water or oil and the unit submerged in a tank of water as in the previous embodiment. To eliminate spring-back when explosive forming high strength metals, e.g. nickel, chrome and vanadium steels, the die is lined with a resilient material 58, e.g. rubber, Fig. 5. Alternatively, the liner is glued to the underside of the blank. Where a progressive draw is desired the use of an additional die is eliminated by first forming the blank with the liner in position and then reforming the blank with the liner removed. To prevent buckling and wrinkling the blank is sandwiched between upper and lower metal blanks and the assemble glued or otherwise bonded together to form a composite blank. After the explosive forming the blanks are separated and then individually trued to a final contour. In a further embodiment the explosive impulse is utilized as a hold-down on the blank by providing above the explosive charge a reflector 100 suspended from a holding member 98 arranged across the top of the tank 78, Fig. 7. By varying the thickness of the explosive charge in a radial direction the amplitude of the hold-down shock is controlled. Large blanks comprising a plurality of small blanks welded together can be formed according to the invention without weld failure. In a further embodiment, a male die 118 is used to form the blank into a domed configuration, Fig. 10. To achieve a uniform thickness in the formed article the initial blank is shaped as shown in Fig. 11a U.S.A. Specification 2,895,405 is referred to. |
