Research of digging force between excavator bucket and loose rocks
                                                                     LI Hong1, LI Guang2, NING Xiaobin3
(1.Taiyuan Heavy Industry Co.,Ltd., Mining Equipments Subco, Taiyuan 030023, China; 2.Taiyuan HeavyIndustry Co., Ltd., Technology Center,Taiyuan 030023,China; 3.School of MechanicalEngineering, Zhejiang University of Technology, Hangzhou 310014, China)

Abstract: Aiming at the calculation of nonlinear digging force produced by interaction of excavator bucket and loose rock, as well as the relation between the digging force and the size and shape distribution of loose rock, the size distribution of loose rock was measured by screening method. The shape distribution of loose rock was measured by random approach.The discrete element model（DEM） of loose rock was established. The transfer of coupling forces between the excavator mechanical mechanism and loose rock was investigated, and a coupling method of multibody dynamics model of excavator attachment and discrete element model of loose rock was proposed. Stick cylinder pressure and bucket cylinder pressure of the excavator attachment were measured by method of coupling mechanical mechanisms and loose rock, and were validated by experimental test. The results indicate that the established coupling model can be applied to calculate digging force, and the size distribution and the shape distribution of loose rock have an influence on the digging force of a hydraulic excavator, and increasing in proportion of chunks of rock and flake rock will increase the digging force.

Key words: excavator bucket; loose rocks; digging force