英语翻译tool failure and tool lifeAs a consequence of continued

英语翻译
tool failure and tool life
As a consequence of continued use ,cuting tools fail to perform satisfactorily .unsatisfactory performance may involve loss of dimensional accuracy ,excessive surface roughness,increased power requirements,physical loss of the cutting edge,or combinations of there.the actual cutting time accumulated before failure is termed tool life and is expressed in minutes.when failure occurs,a tool must be removed and reconditioned,usually by grinding,this involves production loss from machine-down time in addition to the cost of reconditioning the tool and the concurrent loss of tool material.
although they are commonly said to become dull,the failure of tools to perform properly usually is the result of several factors.wear,in several forms,is the primary evident factor .however,heat is also a major factor,because sufficiently high temperatures can cause the tool material to lose its hardness and thus make it more subject to wear.
tool wear occurs in two areas.the major tendency for wear is due to the severe abrasion between the chip and the face of the tool,a short distance from the cutting edge.this results in a crater
being formed in the tool face.when cratering becomes excessive,the cutting edge may break from the tool.due to the section of the tool immediately behind the cutting edge being reduced.cratering is most pronounced in machining ductile materials,which form continuous chips.the second area of wear is on the flank below the cutting edge,resulting from abrasive contact with the machined surface.britle materials tend to cause excessive flank wear ,because the tool cutting edge tends to scrape over the machined surface.flank wear results in a rough machined surface.on carbide tools ,which do not crater readily,and on ceramic tools ,which virtually do not crater ,tool life is arbitrarily taken as corresponding to 0.030 inch of wear land on the flank.

刀具的失效和刀具的寿命
由于刀具持续使用的缘故,刀具失效表现为尺寸精度达不到要求,切削表面过于粗糙.切削力增加,刀刃损伤或者是几种表征的综合.在刀具失效前实际的切削时间的累计值被称作刀具寿命,以分钟表示.当失效发生时,刀具必须卸下来重新修复,一般采用磨削的方式.这里涉及的生产损失包括从机床停机附加刀具重新磨砺同时还有工具材料.
尽管他们通常被称作”变钝”.一般而言刀具的失效是几种因素的结果.几种方式的磨损是首要的明显因素,然而切削热也是一个重要因素,因为十分高的温度能够致使刀具材料降低硬度从而使其更加容易磨损.
刀具磨损的发生有两处:主要的磨损倾向是由于切屑和在离切削刃很近距离的刀面严重磨擦,这样的结果会导致在刀面上形成凹坑.当凹坑逐渐变大,由于刀具强度的瞬间减弱,刀刃就会从刀具上脱落..凹坑是最容易在加工韧性高常常产生长条不间断切屑的情况.第二个磨损的位置在刀侧低于切削刃的地方.(应该是后刀面靠近副切削刃的地方)磨损的原因是因为被加工表面和刀具侧面的摩擦.脆性材料导致更多的刀背磨损.因为副切削刃往往跟被切削表面摩擦.刀背磨损一般产生在粗加工表面的时候.采用碳化物合金刀不容易产生凹坑,采用陶瓷刀,根本不会产生凹坑.刀具的寿命也可以依照刀背磨损的程度来判断,当刀背磨损到0.03inch的时间就是刀具的寿命.,.