800 Каталог GUHRING 2016 Режущий инструмент для обработки наружной и внутренней резьбы Стр.788

Каталог GUHRING 2016 Режущий инструмент для резьбы Стр. 788 0800 Lab2u

Technical section GENERAL INFORMATION FOR TAPPING Taps for ISO metric threads DIN EN 22857 (extract) Thread clearances and fits Fits between internal and external threads are separated by a diagonal stroke, as for example 6H/6g (internal/external thread). The fit has to be selected in conjunction with the appropriate thread connection. The tolerance zones of the tolerance classes fine, medium and coarse are allocated to three screw-in lengths short S), normal (N) and long (L). Generally, the following rules apply for selecting a tolerance class: Fine tolerance zone (S): For precision threads, when only a small variation in the fit is permitted. Medium tolerance zone (N): General application Coarse tolerance zone (L): There are no special precision requirements and in cases where production difficulties may occur, e.g. thread production in hot-rolled rods, deep blind holes or plastic components. Screw-in lengths The quality of thread connection is also affected by the screw-in length. The ISO tolerance system was, especially as regards the pitch diameter, divided into three groups, i.e. S (Short) = short screw-in length N (Normal) = normal screw-in length L (Long) = long screw-in length The following fit should be selected for normal screw-in length N: To ensure a tighter fit of thread connections, we recommend for short screw-in lengths a narrower fit. As far as long screw-in lengths are concerned, fits with a larger tolerance must be used to compensate for pitch deviations. Thread fits with different flank clearance diameter D of internal thread diameter d of external thread Zero profile of thread fit without flank clearance (H/h-fit). diameter D of internal thread diameter d of external thread Thread fit with wide flank clearance (G/g-fit or G/e-fit) in external and internal thread. diameter D of internal thread diameter d of external thread Thread fit with narrow flank (H/g- or H/e-fit) by basic deviation of external thread. Explanation of symbols D = 0 nom. of internal thread Di = Tapping size hole 0 of internal thread D2 = Basic pitch 0 of internal thread d = 0 nom. of external thread d2 = Basic pitch 0 of external thread d3 = Tapping size hole 0 of external thread P = Pitch a = Included angle of thread H = Height of peak to peak thread profile Ao = Upper tolerance limit Au = Lower tolerance limit 788 GUHRING