機(jī)加工（英文）加中文化對照-全文預(yù)覽
【正文】 imensional accuracy of the workpiece is improved since tolerances of 0．00025mm are possible in grinding operations．Grinding machines are classified according to the type of surface produced．Common surfaces and classifications ofgrinding machines are surface，cylindrical，and special machines．The grinding process is of extreme importance in production work for several reasons．(1)It is the most mon method for cutting hardened tool steel or other heattreated steel. Parts are first machined in the unheattreated condition，and then ground to the desired dimensions and surface finish．(2)It can provide surface finish to without extreme cost．(3)The grinding operation can assure dimensions in a relatively short time，since machines are built to provide motions in increments of ten—thousandths of all inch，instead of thousandths as is mon in other machines．(4)Extremely small and thin parts can be finished by this method，since light pressure is used and the tendency for the part to deflect away from the cutter is minimized．On a cylindrical grinding machine the depth of cut is controlled by moving the wheel head，which includes both the wheel and its drive motor．Coolants are provided to reduce heat distortion and to remove chips and abrasive dust．Material removal from ductile materials can be acplished by using a tool which is harder than the workpiece．However during World War II the widespread use of materials which were as hard or harder than cutting tools created a demand for new material—removal methods．Since then a number of processes have been developed which Can effectively remove excess material in a precise and repeatable fashion．There are two types of processes．The first type is based on electrical phenomena and is used primarily for hard materials；the second depends upon chemical dissolution．Electricdischarge machining is a process in which an electrical potential is impressed between the workpiece and the tool，and the current，emanating from a point source on the wor
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