Wheel orientation calculation for helical rake flank sharpening of broaching tools

Abstract

Helical rake flank is an important structure of helical broach tools. Its perfect sharpening is crucial to maintain the working performance of the tool and prolong the tool life, which is obtained via proper wheel orientation and suitable grinding processes. In practical, wheels with diverse profiles are adopted to satisfy the sharpening for various rake flanks. Therefore, wheel orientation identification methods with strong robustness are expected to deal with general helical rake flank sharpening tasks. Besides, proper grinding processes should be devoted to helical rake flank sharpening to improve the quality of broach tool. This study developed a wheel orientation calculation method that combing the specific process for helical rake flank sharpening with involving discrete enveloping. Firstly, a general model for grinding wheel is established, and the swivel-tilt-based orientation and positioning parameters of wheel are given. Then, through approximating the grinding motion as a serial of discrete wheels, the machined profile on the broach tool axial-section is expressed as the external enveloping profile of the intersection curves between the wheels and the tool axial-section. After distinguishing the enveloping profile by points along radial direction, the derivation of the instant contact line was provided. Furthermore, the mathematic model of the specific process about helical broach rake flank sharpen is established to enhance the wheel orientation identification algorithm. At last, both experiments and simulations are implemented to verify the effectiveness of this method and to investigate the influences of the process constrains via solution space.