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机械类 翻译 cad

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Chip formation 切削成型The majority of metal-cutting operations involve the separation of small segments or chips from the workpiece to achieve the required shape and size of manufactured parts. Chip formation involves three basic requirements: (1) there must be a cutting tool that is harder and more wear-resistant than the workpiece material; (2) there must be interference between the tool and the workpiece as designated by the feed and depth of cut, and (3) there must be a relative motion or cutting velocity between the tool and the workpiece with sufficient force to overcome the resistance of the workpiece material. As long as these conditions exist, the portion of the material being machined that interferes with free passage of the tool will be displaced to create a chip.大部分金属切削操作需要从工件上切下碎片或碎屑，来获得所需工件的外形和尺寸。切削成型有三个基本需求：（1）刀具必须有比工件原材更硬更耐磨；（2）刀具和工件之间必须有设计的进刀和切削深度；（3）刀具和工件之间必须有相对运动或切削速度，有足够的压力克服工件原材的阻力。只要有这些条件，在被切削的原材上，阻碍刀具自由切削路径的部分都将变成碎屑。Many possibilities and combinations exist that may fulfill such requirements. Variations in tool material and tool geometry, feed and depth of cut, cutting velocity, and workpiece material have an effect not only upon the formation of the chip, but also upon cutting force, cutting horsepower, cutting temperatures, tool wear and tool life, dimensional stability, and the quality of the newly created surface. The interrelationship and the interdependence among these “manipulating factors” constitute the basis for study of machinability-a study which has been popularly defined as the response of a material to machining.一些可能性和组合的存在也许可以满足这些需求。刀具材料和刀具几何形状的变化，进刀和切削深度，切削速度，及工件材料的变化不仅对碎屑的形成有影响，对切削力，切削能量，切削温度，刀具磨损和刀具寿命，尺寸的稳定性和新切削出来的表面也有影响。这些“控制因素”之间的相互影响和相互依赖构成了基础的机械切削研究-一般被定义为一种材料在切削时的反应的研究Figure 3-2 illustrates the necessary relationship between cutting tool and the workpiece for chip formation in several common machining processes. Although it is apparent that different general shapes and sizes of chips may be produced by each of the basic processes, all chips regardless of process are usually classified according to their general behavior during formation.图3-2说明了在一些普通切削成型加工工艺中，切削刀具和工件之间必要的关系。常见而形状和尺寸不同的碎屑可能在每一个基本工艺中形成，这虽然看起来很明显，但在不考虑工艺时，所有的碎屑常常根据它们在成型中的主要表现分类。Tool life刀具寿命The types and mechanisms of tool failure have been previously described. It was shown that excessive cutting speeds cause a rapid failure of the cutting edge; thus, the tool can be declared to have a short life. Other criteria are sometimes used to evaluate tool life:刀具失效的类型和机能先前已经叙述过了。过高的切削速度会导致刀刃的快速失效，于是刀具的寿命就很短。其它的标准有时候被用来评估刀具的寿命。 1. Change of quality of the machined surface.切削表面质量的改变。2. Change in the magnitude of the cutting force resulting in changes in machine and workpiece deflections causing workpiece dimensions to change.切削力的大小改变，导致机器变化和工件倾斜，使工件尺寸变化。3. Change in the cutting temperature.切削温度的变化。4. Costs, including labor costs, tool costs, tool changing time (cost), etc.费用，包括人力、刀具、换刀耗时等的费用。The selection of the correct cutting speed has an important bearing on the economics of all metal cutting operations. Fortunately, the correct cutting speed can estimated with reasonable accuracy from tool-life graphs or for