NPTF螺牙检测.doc

NPTF螺牙檢測NPT螺纹,用量规检验工件基面的轴向位置来判断螺纹合格与否。外螺纹的小端端面处在量规(环规)的上下限台阶平面之间,或平台阶面为合格。内螺纹要考虑倒角,如倒角的大径小于或等于大端面内螺纹的大径,则看螺纹大端面的位置,如倒角的大径大于大端面内螺纹的大径,则看螺纹与倒角的最后接触点的位置,所看位置处在量规(塞规)的上下限台阶平面之间,或平台阶面为合格。NPTF螺纹的检测需要三支量规,L1/L2/光规或者L1/L3/光规。L1规与上述使用判断方法一致,L2(环规)或L3(塞规)与工件旋合后,基面位置相比L1应保持一致,差异量不大于1/2螺距为合格,否则不合格。光规的判断要根据L1规旋合后的基面位置,从六个台里选择要用的两个台阶,看螺纹基面是否落在这两个台阶面之内,之内合格,之外不合格。&agingInternalThreads–orIngaginginternalthreads,witheror,therearethreeagingmembersinvolved:(1)L-1threadpluggagewhichchecksthethreadelementswithinhandtightengagement;(2)L-3threadplugwhichchecksthethreadsthatwillbeengagedwhenwrenchtight;and(3)6-–orIngagingexternalthreads,eitheror,therearethreemoregagesemployed:(1)6-Stepplainringwhichchecksthemajordiameterofthemalefitting;(2)L-1(thin)ringwhichchecksthethreadelementsoverthedistanceofhandtightengagement;and(3)L-2(thick) GAGINGPRACTICES TAPERPIPETHREADGAGES(NationalTaperPipe)TogageInternaltaperpipethreads,screwthethreadplugfirmlyintotheproduct–,