Investigation of performance characters of tooth surfaces with involute profile concave-convex cylindrical and rack gears

This study has been made in order to model a cylindrical gear with concave-convex threads and its rack by a method different from the ones included in the literature by using CATIA CAD-CAM software and then to set manufacturing codes and enter these codes into 5-axis CNC milling machine.For the purpose of determining the performance characteristics of these gears, spur gears and herringbone gears of the same size have been manufactured and compared and thus their advantages and disadvantages to each other have been determined.This type of gears started to be manufactured in 1970s. However, it has been observed that little research was conducted on them later on. In existing manufacturing methods in the industry, thread profile can not be obtained as evolving as required. Furthermore, a separate special machine is used for manufacturing these gears and separate tool holders and cutters are used for each thread. Such imperatives have prevented the use of these gears in the industry.It has been determined that the most important design parameter of this type of gears in terms of performance characteristics is radius of thread curvature and it has been demonstrated that all modules and thread numbers of this type of gears can be threaded by the computer software which has been developed accordingly.The results obtained from the performance test conducted for these gears are better than the spur gears but worse than the herringbone gears projected in the group. It has been revealed that this type of gears may have many significant areas of use in the industry, especially oil pumps, if their manufacturing is simplified.Keywords: Curved involute profile gears, manufacturing methods, CNC milling machines, finite element, CATIA, ANSYS.