机械精度设计与检测技术 (12).pdf

LIMIT GAUGESECTION 4.11.Limit Plug GaugeThe GO plug gauge is the size of the lower limit of thehole,while the No Go plug gauge corresponds to theupper limit of the hole.In use,the GO end should fullyenter the part;the NO GO end should not.GONO GOGONO GONO GOGO2.Snap GaugeThe GO snap gauge is of a size corresponding to theupper limit of the shaft,while the NO GO snap gaugecorresponds to the lower limit of the shaft.In use,the GOend should fully enter the part;the NO GO end should not.GONO GONO GOGOGONO GOTaylors PrincipleTaylors principle is the foundation of the limit gauge design.According to Taylors principle,the GOgauges shouldcheck all the possible elements of dimensions at a time(roundness,size,location etc.)and the NO GO gaugeshould check only one.To plug gauge,GO gauge must be of corresponding sectionand preferably full length of hole so that straightness of hole canalso be checked.The“NO GO gauge is relatively short and its function isdependent not only on the diameter but also on the circularity ofthe hole.DfeHoleDaDfiInscribed cylinderDfe DminDa DmaxDfeDmin,DaDmaxTaylors PrincipleTo snap gauge,GO gauge must be of corresponding sectionand preferably full length of shaft so that straightness of shaftcan also be checked.The“NO GO gauge is relatively short and its function isdependent not only on the diameter but also on the circularity ofthe shaft.External holeshaftdfedadfidfe dmaxda dmindfedmaxda dminTaylors Principle