Rock and Soil Mechanics ›› 2022, Vol. 43 ›› Issue (11): 3036-3046.doi: 10.16285/j.rsm.2022.5008

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Rock cutting characteristics with single pick and prediction of cutting force based on force chain

DONG Lei1, 2, ZHANG Hua1, LÜ Ji-shuang2, 3, SHI Rui-min1, 2   

  1. 1. School of Mechanical and Power Engineering, North University of China, Taiyuan, Shanxi 030051, China 2. National Engineering Laboratory of Coal Mining Machinery and Equipment, Taiyuan, Shanxi 030032, China 3. Taiyuan Institution, China Coal Technology and Engineering Group, Taiyuan, Shanxi 030006, China
  • Online:2022-11-23 Published:2023-01-15
  • Contact: SHI Rui-min, female, born in 1983, PhD, Reader, mainly engaged in the research on coal mine machinery dynamics and load identification. E-mail:
  • About author:DONG Lei, male, born in 1982, PhD, Associate Professor, mainly engaged in coal mine machinery design and rock failure mechanism research.
  • Supported by:
    the National Natural Science Foundation of China (51875152), the Natural Science Foundation of Shanxi Province (20210302123065) and the Key Projects of Tiandi Science and Technology Co., Ltd. (KY202054).

Abstract: The pick is the main load-bearing object of the mining machinery for cutting coal. Prediction of the cutting force from the working condition is essential to reduce the wear of the pick. The rock was considered as a granular material for single pick cutting simulation using the particle flow code (PFC2D). The influence of the contact state on the cutting force of the single pick was discussed based on the characteristics of the force chain between particles during rock cutting. The cutting force test was carried out with a single pick cutting test equipment. The variation laws of the cutting normal and tangential forces with cutting parameters and the characteristics of falling fragments were obtained. The research results show that the relationship between the number and length of force chains for cutting rock particles with a single pick is consistent with the results of uniaxial compression test in laboratory, demonstrating that the discrete element method can be used to simulate the cutting state of the single pick. The force chain network spreads and extends along the point contact direction, which is related to the cutting angle. The average normal force direction is "peanut"-shaped whereas the tangential force direction is "petal"-shaped. The number of force chains decreases with the decrease of cutting angle and the increase of cutting depth. The length of force chains increases with the increase of cutting distance. The maximum average length is about 8 times the particle size. When the cutting angle is larger, it is easier to form a force chain. The normal and tangential forces of single pick cutting of natural sandstone decrease with the increase of the cutting angle and the decrease of the cutting depth. The coefficient of determination for linear correlation between the size of the cutting fragments and the cutting tangential force is 0.87. Compared with the Evans model, the cutting force prediction model based on the length of force chain improves the accuracy of the normal force by 17.6% and the accuracy of the tangential force by 16.9%. The research results could lay a certain research foundation for the design of cutting pick, mining machinery cutting system and the optimization of cutting technology.

Key words: granular material, single pick cutting, force chain, force prediction