Основной каталог Kyocera 2021 - 2022 - страница 669

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S t L Threading Threading methods TPGB for internal threading Infeed methods Infeed methods Features • The most common threading method. The cutting edge moves toward the center of the workpiece every pass. • Suitable for relatively small pitch size threading. • V-shape chips are generated and chip control may be difficult depending on workpiece material. Radial infeed • Suitable for large pitch size threading. • The wear on the right side edge of the figure (no ap) tends to become greater. • Chips flow to one side. Flank infeed • Revised compound methods of the above flank infeed method. • No “no ap.” condition. • Chips flow to one side. 3˚~5˚ J Flank compound infeed Lead angle of thread Thread's lead angle β as shown in fig. 1 decides from the workpiece diameter“D”(Pitch dia.) And the lead“L”(In case of single-start thread, it is the same as pitch“TP”). By rolling a right-angled triangle around a cylinder and the angle ACB in fig. 2 becomes the lead angle β. The calculation formula is shown as follows. = LπD = nTPπD : Lead angle D: Pitch dia. n: Number of thread TP: PitchL: Lead (In case of single-start thread, it is equal to TP. In case of n-start thread, it is equal to n x TP.) Lead angle L A C B Fig. 1 Fig. 2 Fig. 3 Relief angle of thread Against this lead angle, the threading insert requires side relief angle . Negative type threading insert has no relief angle. When installing the insert in the toolholder, the edge inclination angle (Fig. 3) is set, and at the same time front relief angle as well as side relief angle are generated to the insert. Side relief angle is described by the following formula. (Fig. 4) = tan ×tan ( ) Table 1 A Symbol e.g.)Xα: Side relief angle Side relief angle α t PNA : Inclination angleafter installingExternal insert:10˚insertInternal insert:15˚Inserts External Internal A-A Section A Metric: 60˚PNA: Insert's threadangleTapered pipe: 55˚60˚ thread (M, UN, NPT)5˚ 49 8˚ 47 30˚ trapezoidal: 30˚ S: Insert thickness 55˚ thread (W, G, PT) 5˚ 14 7˚ 56 X 30˚ trapezoidal (Tr) 2˚ 43 5˚ 7 Fig. 4 Ref. to table 1 for the side relief angle depending on the insert type. However, the side relief angle is set for 1˚ in the traveling direction by the toolholder itself, so that the actual side relief angle becomes +1˚. J53