Machinery's Handbook, 31st Edition
Knurls and Knurling 1057 The term Diametral Pitch applies to the quotient obtained by dividing the total number of teeth in the circumference of the work by the basic blank diameter; in the case of the knurling tool, the diametrical pitch would be the total number of teeth in the circumference divided by the nominal diameter. In the Standard, the diametral pitch and number of teeth are always measured in a transverse plane that is perpendicular to the axis of rotation for diagonal as well as straight knurls and knurling. Cylindrical Knurling Tools.— The cylindrical type of knurling tool is comprised of a tool holder and one or more knurls. The knurl has a centrally located mounting hole and is pro vided with straight or diagonal teeth on its periphery. The knurl is used to reproduce this tooth pattern on the work blank as the knurl and work blank rotate together. * Formulas for Cylindrical Knurls
(1) (2) (3) (4) (5) (6) (7)
P = diametral pitch of knurl = N t ÷ D nt D nt = nominal diameter of knurl = N t ÷ P N t = no. of teeth on knurl = P × D nt
*P nt = circular pitch on nominal diameter = π ÷ P *P ot = circular pitch on major diameter = π D ot ÷ N t D ot = major diameter of knurl = D nt − ( N t Q ÷ π ) Q = P nt − P ot = tracking correction factor in Formula
Tracking Correction Factor Q: Use of the preferred pitches for cylindrical knurls, Table 2, results in good tracking on all fractional work-blank diameters that are multiples of 1 ⁄ 64 inch for 64 and 128 diametral pitch, and 1 ⁄ 32 inch for 96 and 160 diametral pitch; an indication of good tracking is evenness of marking on the work surface during the first revolution of the work. The many variables involved in knurling practice require that an empirical correction method be used to determine what actual circular pitch is needed at the major diameter of the knurl to produce good tracking and the required circular pitch on the workpiece. The empirical tracking correction factor, Q , in Table 2 is used in the calculation of the major diameter of the knurl, Formula (6).
P ot
h
R
F
Ψ
D ot
D nt
A
Straight
Diagonal
45° Bevel to Depth of Teeth Optional
Cylindrical Knurl * Note: For diagonal knurls, P nt and P ot are the transverse circular pitches that are measured in the plane perpendicular to the axis of rotation.
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online