Study on Rock Fragmentation Mechanism under Single Tooth and Shape Optimization by Indentation Test

Tooth shape is one of the key parameters influencing fragmentation efficiency of the toothed cutter. In this paper, the indentation tests of picked tooth, conical tooth, wedge tooth as well as spherical tooth were conducted, and then the issues on fragmentation mechanism by different teeth and optimization of tooth shape were investigated. The influence of tooth shape and loading force on the characteristics of loading force-penetration curve, penetration depth, fragments volume, radius of the fragmentation crater as well as the distribution characteristics of fragments were discussed. Then, the fragmentation fractal theory was adopted to optimize the tooth shape and loading force. The research results show that: with the increase of loading force, the influence of tooth shape on rock fragmentation indicators such as penetration depth, fragments volume and fragmentation crater radius increases accordingly; the fragments present fractal characteristics in particle size, and the fragmentation effect can be evaluated by combining the fragmentation fractal dimension with the fragments volume and other indicators; for granite rocks, the fragmentation fractal dimension induced by the picked tooth is the lowest, and the fragments volume, fragmentation crater radius and penetration depth are the largest, thus the pick tooth is suggested to be used for excavation of hard rocks, and 100 kN is selected as the optimized loading force.