The Method of Calculating Optimal Recovery Parameters for Internal Broaches

This article proposes a method for recovery of internal broaches, which will help to increase operating time and decrease costs. The method is based upon an established and analytically described dependence between permissible values of the rounded cutting edge radius and the linear wear along the rear face of an internal breach’s tooth. Recommendations for calculating values of grinding of teeth’s front surfaces have been developed, taking into account the principle of equal stability of the roughing and finishing teeth. This makes it possible to carry out their controlled sharpening. The total number of resharpening cycles is justified taking into account the strength of the roughing teeth, the tolerance for the machined surface, and ensuring the specified roughness of the machined surface throughout the entire life of the tool. The proposed recommendations for designating operating and recovery parameters of broaches may help to increase the tool’s service life by 1.25–1.4 times, decrease the tool’s consumption rate per batch by up to 20%, and decrease the cost of broaching by 25–30%. The method has been automated using MS Excel. The system of interconnected spreadsheets contains input data, such as the parameters of a processed surface, design and geometric parameters of a broach; values of grinding-off from the front surfaces of the broaching teeth; and the number of permissible resharpenings. Testing of this method in industrial conditions has shown that it efficiently and effectively chooses tooth profile parameters and tool operation modes during the design stage, with recovery parameters taken into account.