Lesson 27 metal-cutting process 金属切削加工 机械专业专业英语教学用书.pptVIP

Lesson 27 metal-cutting process 金属切削加工 Metal-cutting processes are extensively used in the manufacturing industry. They are characterized by the fact that the size of the original workpiece is sufficiently large that the final geometry can be circumscribed（外接）by it, and that the unwanted material is removed as chips, particles, and so on. The chips（去屑）are a necessary means（必要手段）to obtain the desired tolerances, and surfaces. The amount of scrap may vary from a few percent to 70%~80% of the volume of the original work material. Lesson 27 metal-cutting process 金属切削加工 Owing to the rather poor material utilization of the metal-cutting processes, the anticipated scarcity（预料到的短缺）of materials and energy, and increasing costs, the development in the last decade has been directed toward an increasing application of metal-forming processes, however, die cost（模具成本）and the capital cost（设备成本）of machines remain rather high; consequently, metal-cutting processes are, in many cases, the most economical, in spite of the high material waste, which only has value as scrap. ...... Lesson 27 metal-cutting process 金属切削加工 ……Therefore, it must be expected that the material removal processes will for the next few years maintain their important position in manufacturing, furthermore, the development of automated production systems has progressed more rapidly for metal-cutting processes than for metal-forming processes. Lesson 27 metal-cutting process 金属切削加工 In metal-cutting processes, the imprinting of information（信息传递）is carried out by a rigid medium of transfer (the tool刚性介质（刀具）传递实现), which is moved relative to the workpiece, and the mechanical energy is supplied through the tool. The final geometry is thus determined from the geometry of the tool and the pattern of motions of the tool and the workpiece. The basic process is mechanical: actually, a shearing action combined with fracture（剪切和断裂相结合的过程）. Lesson 27 metal-cutting process 金属切削加工 As mentioned previously the unwanted material