Study On Friction And Wear Properties Of The Ring Of The TBM Cutter Under Laser Pre-drilling Condition

Full section rock tunnel boring machine(hereinafter referred to as TBM),because of its high construction efficiency,reliability,good safety and other advantages,is widely used in tunnel construction,national defense engineering and other important fields.And in the construction stage,often encounter "three high"(high confining pressure,high geological hardness and high quartz content of the rock)and other extreme geological conditions,make the hob rock breaking conditions are extremely bad,resulting in hob loss failure is very serious,and then lead to the entire construction process of low efficiency,high construction cost.Therefore,prolonging the wear life of TBM hob has become a key problem urgently needed to be solved in TBM field.Given that laser-assisted rock breaking technology has made a great breakthrough in the field of oil drilling,laser-assisted TBM hob rock breaking research has great research potential and economic value.At present,most researches focus on the mechanism of laser-hob coupling rock breaking,but ignore the research on the friction and wear performance of cutter ring.To this end,this paper carried out the rock breaking test and simulation of TBM cutter ring under the condition of laser pre-drilling,and studied the influence law of rock type,cutter ring penetration speed,blade width and cutter ring cutting speed on the friction and wear performance of the cutter ring.The main research contents of this paper are as follows:(1)First of all,the same scale proportional cutting ring as the engineering hob material was prepared;Secondly,the friction and wear testing machine was used to study the wear amount and friction coefficient of cutter ring material under different sliding speeds and different vertical forces,and the microscopic friction and wear mechanism of cutter ring material samples under sliding conditions was revealed.(2)Orthogonal experiments were carried out with laser focal length,laser power and laser action time as variables.Using laser hole,hole depth and volume as evaluation indexes,range analysis,comprehensive evaluation analysis and variance analysis were carried out,and the optimal combination of laser drilling parameters was obtained as laser focal length of 20 mm,laser power of 100 w and operation time of 4s.It was concluded that the significant factor affecting laser drilling effect was laser focal length.(3)According to the principle of thermodynamics,the model of laser drilling process was simplified and the problem hypothesis was made.The temperature distribution of rock samples and the process of rock fragmentation under laser heat source were studied.Then,based on the predicted laser hole size,the rock breaking process of the scaled-down proportional cutter ring under the condition of laser pre-drilling is simulated and analyzed,and the changing law of rock fracture morphology and contact stress in the process of cutter ring rock breaking is determined.(4)First,the rock breaking test of TBM cutter ring was carried out under the condition of laser pre-drilling.The influences of four factors including rock type,cutter ring penetration speed,blade width and cutter ring cutting speed on cutter ring wear,rock breaking and vertical cutting force were studied.Secondly,combined with the microscopic morphology of the blade bottom,the microscopic friction and wear mechanism of the blade ring sample under rolling condition was preliminarily revealed.Finally,an accurate measurement method for rock breakage of cutter ring based on three-dimensional coordinate scanning is proposed.The results show that the abrasion removal mechanism between the cutter ring and the rust stone is mainly furrow deformation,while the abrasion removal mechanism between the cutter ring and the rust stone is mainly brittle fracture.