809 Каталог GUHRING 2016 Режущий инструмент для обработки наружной и внутренней резьбы Стр.797

Каталог GUHRING 2016 Режущий инструмент для резьбы Стр. 797 0809 Lab2u

GENERAL INFORMATION THREAD FORMING Definitions, angles, centres, thread tolerances and fits Thread portion driving square without oil grooves with oil grooves Types of centres (standard, to DIN 2197/DIN 2175) on cutting section on shank solid cone XI chamfer internal centre (form A or R to DIN 322 acc. to manufact. specification) Centre on cutting section Thread dia. range with chamfer forms with chamfer form Centre on shank mm A, C, D, E B < 5.6 O O O O O > 5.6 12.8 CD O O O O O O O O > 12.8 O O Thread tolerances 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. 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. 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. 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. S (Short) = short screw-in length N (Normal) = normal screw-in length L (Long) = long screw-in length GUHRING 797 Technical section