Bionic Research Of Soil Anti-adhesion Rotary Drilling Tools

At present,rotary drilling rig occupies an important position in the field of piling machinery,and is widely used in urban construction,highway and railway construction.As the most widely used rotary drilling tool with rotary drilling rig,rotary drilling buckets are often used in the geology with strong adhesion such as silt,dense clay and silty subclay.Soil adhesion on the drilling buckets is very common,which seriously affects the working efficiency and working quality of rotary drilling rig.Therefore,it is urgent to develop a new type of rotary digging drill bucket with the function of adhesion reduction and desorption.The application of bionics in adhesion reduction and desorption provides a new research idea for the development of the new rotary digging drill bucket.Using bionic approch,a new drill bucket part of rotary digging drill bucket was designed in this work.Based on the bionic non-smooth theory,the convex hull structure of dung beetle and the ridged structure of pangolin scales were studied,and a serial of bionic pressuire plates and a smooth plate were designed.In this work.The bionic pressure plates were designed with equal diameter convex hull,unequal diameter convex hull and ribs,respectively.The application principle of electroosmosis phenomenon in adhesion reduction and desorption of earth-touching parts was also considered in this work,and the electroosmosis enhancement tests were designed to test the adhesion reduction and desorption effect of the bionic structure pressure plate.The basic parameters of the soil sample,such as the particle size distribution,density,Poisson’s ratio and elastic modulus were determined,and the soil with different water contents were also preparaed in this research.The adhesion reduction verification tests in a soil bin of different pressure plates were carried out by MTS electronic universal testing machine.The effect of moving speed and holding time were considered in the soil bin tests.The adhesion-reducing effect of the three bionic plates and the smooth reference plate was investigated.Then,the effect of soil moisture content,electroosmotic voltage and electroosmotic action time on the adhesion-reducing result of different bionic structures was explored in the electroosmotic test.After analyzing the result of the experiment,I conclude which structure is the best and get the factors that affect the experiment.It was found that under the same test conditions,the pressure plate with equal diameter convex structure got the lowest adhesion force and had the strongest adhesion reduction effect.EDEM was used in this work to conduct discrete element simulation analysis on the soil adhesion force.JKR contact model was chosen to define the interaction between soil and tools,and the soil parameters of the model were obtained from literatures and experiments.The soil resistance on bionic pressure plate and smooth pressure plate were analyzed by using EDEM.The simulation results showed that the bionic plate with convex structure had the minimum soil resistance.Therefore,a bionic drill bucket with convex structure was designed.The simulation results showed that comparing with the smooth drill bucket,the bionic convex drill bucket had less resistance during penetrating the soil,and the soil adhesion mass was reduced by22.79%,the adhesion force was reduced by 25.7%.Thus the bionic drill bucket has better performance on soil adhesion reduction.The bionic structure which has optimal performance on soil adhesion reduction was found using simulation tests,Then the bionic convex drill bucket and smooth drill bucket were fabricated and tested in soil bin.The test results showed that comparing with the smooth drill,the soil adhesion of bionic convex drill bucket was reduced by20.18%,and the soil adhesion mass was reduced by 24.04%.Besides,the effect of adhesion reduction was greatly improved by electroosmosis.The bionic convex drill had great soil adhesion reducing effect.