Tham khảo tài liệu 'gear noise and vibration episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 220 Chapter 13 Fig Sketch of effects at a correct centre distance and b extended centre distance. Fig. shows diagrammatically the difference between two pairs of teeth meshing at correct and extended centres to give the same changeover points. The test requirement is then to decide what increase in the centre distance will give crossover points in exactly the same positions up the profiles of the gears as when handing over contact under loaded conditions. The requirement is to find the exact positions up the profiles not along the roll pressure line where handover occurs for the original contact geometry and match these to the handover points at extended centres. This is an iterative calculation and it is simplest to use a computer routine to assist the process. program for finding centre distance change for contact ratio 2 gears for TE for changeover. Work in terms of nominal module 1 phio 18 2 pi 360 design pressure angle 18 at contact ratio 2 n 1 32 number of pinion teeth n2 131 number of wheel teeth brl nl cos phio br2 n2 cos phio base radii psil tan phio 2 pi nl psi2 tan phio 2 pi n2 determine unwrap angles psi at changeover points assuming both are 1 base pitch away from pitch point these unwrap angles must be the same for extended test to be the same points on the flanks but will occur at roughly base pitches away from the pitch point Copyright Marcel Dekker Inc. All rights reserved. Marcel Dekker Inc. 270 Madison Avenue New York New York 10016 High Contact Ratio Gears 221 take first approximation to new pressure angle phil as due to centres moving 1 module apart so phil acos cos phio brl br2 brl br2 cos phio new angle then calculate distances from pitch point to changeover points divided by original base pitch rl brl psil - brl tan phil pi cos phio new pressure angle only original base radius real r2 br2 psi2 - br2 tan phil pi cos phio conratio rl r2 dispf angle rl r2 contact ratio disp phil rl r2 conratio line 18 phi2 input enter
