الفهرس 
GEARS OF CIRCULAR-ARC TOOTH-PROFILEOnly 14 pages are availabe for public view
 |  | from | 233 |  |  |
| | | from | 233 | | |
Abstract
The main objective of this work is to study the effect of gear geometry on the discharge and pressure of gear pumps. Gears of circular- arc tooth profile can carry loads between three and six times greater than those carried by involute gears of the same size. In this study we have used gears of circular- arc tooth profile as gear pumps and have compared between this type of gearing and spur, helical gear pumps according to discharge and pressure.
The chosen module change from 2 to 16 mm, number of teeth change from 8 to 20 teeth, pressure angle change from 10 to 30 deg, face width change from 20 to 120 mm, correction factor change from –1 to 1, helix angle change from 5 to 30 deg and radii of curvatures equal 1.4, 1.5, 2, 2.5, 2.75, and 3m are considered. We deduced that the tooth rack profile with radius of curvature equal 2.5, 2.75, 3m for all- addendum circular arc tooth and convex-concave tooth profile. We derived equations representing the tooth profile, and calculated the points of intersections between curves of tooth profile. We computed the volume of oil between adjacent teeth. Computer program has been prepared to calculate the discharge and pressure from the derived formulae with all variables for different types of pumps.
Curves showing the change of discharge with module, number of teeth, pressure angle, face width, correction factor, helix angle, and radius of curvature are presented. Also the curves for pressure change with the same variables are deduced.
The results show that:
A- Discharge
1) The discharge increases with increasing module, number of teeth, positive correction factor, face width and radius of curvature of the tooth.
2) The discharge increases with increasing pressure angle to a certain value and then decreases with further increases pressure angle.
3) The discharge decreases with increasing helix angle.
4) The convex – concave circular - arc gears gives discharge higher than all- addendum circular arc, spur, and helical gear pumps.