Có một phương pháp sử dụng H-yếu tố, trong đó "H" đại diện cho kích thước của một hạt, với P-yếu tố được sử dụng ở những nơi khác. Sự khác biệt chính là thứ tự tính toán, trật tự thấp nhất cho H-yếu tố, với các tính toán để cho P-yếu tố cao hơn. Phương pháp hội tụ Sử dụng H-yếu tố. | METAL STAMPING DIES AND THEIR FUNCTION 143 METAL STAMPING DIES AND THEIR FUNCTION FIGURE 3-58 Section view of a pillar subpress die. is immersed in the tank as well. When exposed to the shock wave the part is forced to take on the shape of its die. This process may be found useful for all tube-forming processes that alter the tube s profile and shape such as complex forming bulging and expanding. 3-4-3 Forming With Explosives Explosive forming is not really a new process but very similar to electromagnetic forming described in Sec. 3-4-1. It has been around for years with differing results. Some consider it a superb method of manufacturing others have lost their buildings to it in an explosion. It is a process in which safety cannot be overemphasized. The energy derived from explosives can be of tremendous intensity and the use of such force for forming processes is certainly tempting. During the forming process the explosive material either in pieces or encapsulated is placed in a water-filled tank alongside or within a die with the material to be formed. The charge when detonated prompts release of a great amount of steam and gas during a relatively short time interval. Such an action creates a strong shock wave in the liquid medium which affects the part to be formed by forcing it to take on the shape of the die. Objects suitable for utilization of such manufacturing process are mainly tubes which may be bulged expanded or squeezed to tight tolerances and formed into uneven shapes. Metal plates may be drawn to wildest shapes many of them unattainable otherwise. 3-4-4 Superimposed Vibrations Ultrasonic waves when applied to the molten metal promote the development of additional currents within its mass which in turn produce a more effective mixing which results in an improved homogeneity of the metal. When applied to the metal as it begins to Downloaded from Digital Engineering Library @ McGraw-Hill Copyright 2004 The McGraw-Hill
