Research On Stress Testing Method Of Drill Type Coal Cutter's Bit

Coal resource is the important resources in our country.The mining of coal resources mainly relies on the coal winning machine.Drill type coal winning machine is a type of coal cutter,mainly used for thin seam mining.To reduce the faults of coal winning machine is the premise of safe and reliable operation of the coal winning machine.The most common fault of mechanical parts on winning machineis is broken bit.Stress tests can discover the force of the drill bit and prevent drill fracture accident.At present,the stress testing methods of drill bit mostly can only detect surface stress.However,most of the drilling tool fracture accident is caused by large internal stress.Looking for a new stress testing method to test the bit internal stress is of great significance.To solve above problems,this article will revolve around shearer bit stress magnetic flux leakage detecting technology to carry out the research study.The main work is as follows.First of all,reviewing relative data,this paper puts forward several common stress testing method of shearer bit and detailedly analyze its detection mechanism.Its mathematical model is given.On this basis,the advantages and disadvantages of the several kinds of testing technology are compared.Secondly,this paper introduces the structure and working principle of spiral auger shearer.The main physical properties of coal and rock are detailedly elaborated and the force mathematical model of bit is built.Based on the actual case,through the simulation,this paper analyze the type of stress of drill and stress distribution.Again,this paper briefly describes the basic principle of magnetic flux leakage testing and gives the theoretical expression of Point dipole,line dipole and dipole leakage magnetic field.Then,the leakage magnetic field distribution characteristics of infinite long rectangular model,V type model and holes model are analyzed in this paper.A method which can be used to detecting the force of drill by magnetic flux leakage test is proposed.Finally,from the macroscopic thermodynamic theory,the force magnetic coupling finite element mathematical model of bit is built up.On this basis,by the electromagnetic simulation software ANSYS software,this paper gives the bit's changes of curve of the magnetic induction intensity and vecto,flux density and the magnetic field lines of internal ferromagnetic under the effect of different stress.By the experiment of drill's load,we verify the correctness of the model.The rationalityof the bit stress testing is verified by the way of magnetic flux leakage test.