英语翻译A very important fact of the manufacturing science is that it is almost impossible to obtain the desired basic size when processing a workpiece.This is actually caused by the inevitable,though very slight,inaccuracies inherent in the mach

英语翻译A very important fact of the manufacturing science is that it is almost impossible to obtain the desired basic size when processing a workpiece.This is actually caused by the inevitable,though very slight,inaccuracies inherent in the mach
英语翻译
A very important fact of the manufacturing science is that it is almost impossible to obtain the desired basic size when processing a workpiece.This is actually caused by the inevitable,though very slight,inaccuracies inherent in the machine tool as well as by various complicated factors like the elastic deformation and recovery of the workpiece and/or?the fixture,temperature effects during processing,and sometimes the skill of the operator.Since it is very difficult to analyze and completely eliminate the effects of these factors,it is more feasible to establish a permissible degree of inaccuracy or a permissible deviation from the nominal dimension that would not affect the proper functioning of the manufactured part in a detrimental way.The deviations from the basic size to each side ( i.e.,positive or negative)determine the high and the low limits,respectively,and the difference between those two limits of size is called the tolerance.The tolerance is an absolute value without a sign.As you may expect,the magnitude of the tolerance is dependent
upon the basic size and is designated by an alphanumeric symbol called the grade.There are eighteen standard grades of tolerance in the ISO system,and the tolerances can be obtained from the formulas or the tables published by the ISO.It is obvious that smaller tolerances require the use of high?precision machine tools in manufacturing the parts and therefore increase production costs.
Before two components are assembled together,the relationship between the dimensions of the mating surfaces must be specified.In other words,the location of the zero line to which deviations are referred must be established for each of the two mating surfaces.This actually determines the degree of tightness or freedom for relative motion between the mating surfaces.There are basically three types of fits,namely,clearance fit,transition fit,and interference fit.In all cases of clearance fit,the upper limit of the shaft is always smaller than the lower limit of the mating hole.This is not the case in interference fit,where the lower limit of the shaft is always larger than the upper limit of the hole.The transition fit,as the name suggests,is an intermediate fit.According to ISO,the internal enveloped part is always referred to as the shaft,whereas the surrounding surface is referred to as the hole.Accordingly,from the fits point of view,a key is referred to as the shaft and the keyway as the hole.
There are two ways for specifying and expressing the various types of fits,the shaft?basis?and the hole?basis?systems.The location of the tolerance zone with respect to the zero line is indicated by a letter,which is always capital for holes and lowercase for shafts,whereas the tolerance grade is indicated by a number,as previously explained.Therefore,a fit designation can be H7/h6,F6/g5,or any other similar form.

英语翻译A very important fact of the manufacturing science is that it is almost impossible to obtain the desired basic size when processing a workpiece.This is actually caused by the inevitable,though very slight,inaccuracies inherent in the mach
加工时,几乎不可能得到所要求尺寸的工件是制造科学的一个非常重要的事实.这事实上是由机床自身固有的误差所引起的,尽管非常细微,同时还有其他各种复杂的因素,如工件或固定装置的弹性变形和复位,或者加工时的温度,有时是加工操作人员的技术水平.因为很难去分析和完全排除这些因素所造成的影响,所以在不影响完工的工件正常功能的基础上,确定一个可接受的误差或偏斜度更可行.从标准尺寸到两边的偏差（正或负）分别决定了高和低的界限,两个尺寸界限之间的不同就叫做容差.容差是一个没有正负号的绝对值.像你所认为的那样,容差的等级是取决于基础尺寸并且被标为字母数字符号.在ISO系统中有18个容差等级标准,容差可以通过公式和ISO发布的运算表获得.显然,更小的容差需要在加工部件是用高精准的机床,从而提高产品成本.
在安装组合之前,两个部件相交的面积尺寸之间的关系必须被确定下来.换句话说,0线到哪个相关误差的位置必须为两个贴合面确定下来.这正决定了俩个贴合面之间相对活动的松紧程度.基本上有三种配合类型,即间歇配合,过渡配合和干涉配合.在所有的间歇配合案例里,轴的上限总是要比配合孔的下限要小.在干涉配合案例中就不是这样,轴的下限总是比配合孔的上限大.过渡配合,像它的名字所暗示的,是一种介于中间的配合方式.按照ISO标准,内部被包裹的部分总是作为轴,同时外面包围的面被认为是配合孔.因此,基于配合的方式,钥匙就是轴,而钥匙孔就是配合孔.
有两种方式可以描述配合的各种类型,即以轴为基础的系统和以配合空为基础的系统.容差区域0线的位置用一个字母来标示,大写代表配合孔,小写代表轴；同时像前文提到的,容差等级用一个数字来标示.所以,一个配合的名称可以是H7/h6, F6/g5,或任何其他更小的型号.