Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
The article describes a method for obtaining polygonal bores by broaching predrilled circular bores. The figure shows workpiece 1 having predrilled bore 2 which is to be reshaped to a polygonal bore. Workpiece 1 is mounted on the spindle of a lathe (not shown) and rotated at N turns per second around the lathe spindle axis. Setscrew 5 fixes broach 3 to spindle 4, rotatable on high efficiency bearings 6, with the broach axis forming an angle a with the lathe spindle axis. During broaching process, the center of the frontal cutting face of broach 3 is moved along the lathe spindle axis at a constant speed Va (mm/second), and upon engaging with the internal surface of bore 2, it is also rotated by workpiece 1 while it penetrates progressively into bore 2.