形成过程.doc

编号： 毕业设计(论文)外文翻译 （原文） 学 院： 机电工程学院 专 业：机械设计制造及其制动化 学生姓名： 学 号： 指导教师单位： 机电工程学院 姓 名： 周定礼 职 称： 工程师 2012年 5 月 15 日  Forming Processes Charles W. Beardsley Abstract: Forming can be defined as a process in which the desired size and shape are ob-tained through the plastic deformations of a material. The stresses induced during the process are greater than the yield strength, but less than the fracture strength, of the material. The type of loading may be tensile, compressive, bending, or shearing, or a combination of these. This is a very economical process as the desired shape, size, and finish can be obtained without any significant loss of material. Moreover, a part of the input energy is fruitfully utilized in improving the strength of the product through strain hardening. Keywords: Forming Rolling Forging Extrusion 1.1 Forming The forming processes can be grouped under two broad categories, namely, cold forming, and hot forming. If the working temperature is higher than the recrystalliza-tion temperature of the material, then the process is called hot forming. Otherwise the process is termed as cold forming. The flow stress behavior of a material is entirely different above and below its recrystallization temperature. During hot working, a large amount of plastic deformation can be imparted without significant strain hard-ening. This is important because a large amount of strain hardening renders the mate-rial brittle. The frictional characteristics of the two forming processes are also entirely different. For example, the coefficient of friction in cold forming is generally of the order of 0.1, whereas that in hot forming can be as high as 0. 6. Further, hot forming lowers down the material strength so that a machine with a reasonable capacity can be used even for a product having large dimensions. The typical forming processes are