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1、SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERINGUNIT SIX MANUFACTURING PROCESSES LESSON ONE MACHINING PROCESSES process 过程 工艺规程,方法The manufacturing (or production) process of a factory, in a broad sense, is the sum total of separate processes involved in the conversion of raw materials or s
2、emi-finished products into final products. As far as a factory is concerned, its products can be blanks, finished parts, mechanisms, units or end products. The raw materials or semi-finished products used for manufacturing the products are often produced and supplied by other factories. Sometimes th
3、e products of the factory need to be further processed by other factories before they become the end products.in a sense 从某种意义上说 sum total 总数 as far as 至于 blank 空白的 毛坯，坯件 part 部分，零件 mechanism 机构，机理 unit 单位，部件SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERINGThe manufacturing (production) proc
4、ess includes not only processes acting directly upon the manufactured objects, but also preparatory processes (such as production planning, process planning, production scheduling, tooling preparation, etc.) and auxiliary processes (such as equipment maintenance, inter-shop material and workpiece ha
5、ndling, cutting tool sharpening, quality inspection, production statistics, cost accounting, etc.)The processes, acting directly upon the manufactured objects, change the shape, dimensions and properties of raw materials or semi-finished products, or assemble parts into final products. These process
6、es are manufacturing (or production) processes in a narrow sense.cost accounting 成本会计， 成本核算narrow sense 狭义SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERINGThere are various manufacturing processes used for converting raw materials into finished parts. These processes include casting, forging
7、, welding, punching, forming, machining, heat- treatment, plating, coating, and so on. Among them, the machining process plays an important role in the manufacture of parts.The machining process of a part may include various machining operations, such as turning, milling, drilling, grinding, broachi
8、ng, gear-cutting, etc. depending on the required shape, dimensions, accuracy and surface quality of the part. In order to ensure the quality of a completed part, well-planned processes documents are necessary.casting 铸造 forging 锻造 welding 焊接 punching 冲压 forming 成形加工heat-treatment热处理machining 切削加工pla
9、ting 电镀 coating 油漆 operation 操作,工序 turning 车削 milling 铣削 drilling 钻削 grinding 磨削 broaching 拉削 etc.= et ceteraSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERINGAfter a new product is designed, planning the processes for its component parts is the first step of the preparatory work for manufact
10、uring. The planned process documents serve as the basis and initial data for all other preparatory work, and the rules and regulations for production operations, the quality of process plans influences directly the degree of complexity of the preparatory work for manufacturing, the time length of th
11、e preparatory stage, the quality of parts and products manufactured, the degree of complexity of production scheduling and operations sequencing, the makespan of parts and products, and the production costs. Hence process planning is of key importance to manufacturing.制造时间SCIENCE AND TECHNOLOGY ENGL
12、ISH FOR MECHANICAL ENGINEERINGOften there exist alternatives of process plans for manufacturing a part. The quality of a process plan should be evaluated from a technological as well as an economical standpoint. A good process plan not only ensures the required quality of manufactured parts, but als
13、o reduces the production cost. In process planning, a comprehensive analysis of part structure, material and technical specifications, production volume and manufacturing conditions must be made, so as to properly make all the decisions related to the planning of the process. Many decisions should b
14、e made in machining process planning. Selection of the blank and its manufacturing method. Selection of machining methods for part surfaces. Determination of operations sequence. Determination of workpiece setting method for each operation.SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERINGSel
15、ection of machining equipment and tooling for operations. Determination of operating procedure for each operation. Determination of operational dimensions and tolerances for machining operations. Selection of machining conditions and determination of time standards of each operation. Composition of
16、Machining Processes A machining process is made up of a number of operations through which raw materials or blanks are transformed into parts. The basic components of machining processes are operations. An operation is a complete portion of the machining process for cutting, grinding, or otherwise treating, a workpiece (or several workpieces simultaneously) at a single workplace. An operation is accomplished by one
