Experimental Studying On Physical Simulation Of Bit-rock Cutting Of Surface Miner

At present, surface miners are used widely in coal and soft rock mine at thedomestic, but in the hard rock it remains to be popular, for using surface miner toextraction different hard rocks rationally and efficiently, it is necessary to understandthe bit-rock cutting law of surface miner. This papers is on the basis of NationalNatural Science Foundation project “Temporal Principle Research of Fine Mining forOpen Pit Mine”. Firstly, making analysis of kinematics and mechanical on surfaceminer’s cutter drum and bit. Then using Merchant cutting model, Evans pulled failuremodel, Nishimatsu shear failure model to establish rock breaking model theoretically.Introduced stress wave damage theory, and analyzed the stress waves’s propagationand damaging effects on the internal rock. Through the static cutting test and impactcrushing test, used mine conical bits as cutting tool, studied the destruction law of therock under the bit-cutting role. The results and conclusions achieved are as follows:(1) In this simulated testing conditions, the best impact crushing parameter is1mimpacting height and20mm impacting thickness, at this time, the impacting velocityis4.83m/s, impacting energy is70J, the largest crushing volume reached12320mm3.On the impacting surface, the crack expanded to20mm from the edge, on the upsurface the crack to44mm,3/10of testing blocks, the ratio of intercept length andcutting thickness is4.2.(2) Firstly, the testing blocks were under compressive stress, and the stressreached a peak, then it gradually decreased, after that the tensile stress generated andreached a peak. By curve fitting, obtained the relationship of peak compressive stressand peak tensile stress with measuring point distance.(3) In the static pressure cutting tests, the bits intrsiving depth increasing withthe cutting thickness and then remained stable, but in the impact crushing tests, thebits intrsiving depth substantially unchanged and much smaller than the staticpressure cutting tests’ intrsiving depth. The static pressure cutting’s peak stress issmaller than wich of impact crushing.The analysis of crack size under the best impact crushing parameter can providethe basis for the prediction of impacting crush scope and determination of cutterspacing. Under the impacting action, testing blocks’ destruction is the result of joint action of tensile-compressive stress, in which the tensile stress plays a dominant role.The testing bocks’ compression-tensile strength under impacting load is significantlyhigher than the static load’s.