Accuracy of Straight Bevel Gear by End Mill Using CNC Milling Machine

Abstract

Straight bevel gears are usually manufactured with various machines and systems, and the tooth profiles are produced by grinding or machining by means of a tool with many cutting edges. In recent years, the straight bevel gear has been manufactured by an end mill using a CNC milling machine because the use of the auxiliary apparatus, special cutters, and special machine tools are not needed. Using this method, the gear manufacturing with high accuracy is important problem. In this paper, the coordinate measurement of the straight bevel gear manufactured in this method is performed and the gear accuracy is evaluated. The tooth profiles of a straight bevel gear generated by a quasicomplementary crown gear instead of a conventional complementary crown gear is introduced. For this study, first the tooth profiles of the straight bevel gear were modeled using a 3D-CAD system and the gear was manufactured by an end mill using a CNC milling machine based on a CAM process. Afterward, the coordinates of many points on the gear tooth surfaces were measured at random using a coordinate measuring machine. This coordinate measurement provides the information about the factors relation to the gear accuracy such as pressure angle, tooth angle error, root cone angle, and apex to back and so on. Therefore, the values of the above factors were estimated and were compared with the theoretical ones, respectively.