Structural Optimization And Experimental Research Of Rotary-Percussion-Compact Hammer

The Rotary-Percussion-Compact Drilling technology is high efficiency in soil layer drilling, make the bit crush soil using the impact force produced by high-speed motion of hammer piston and make the soil Squeeze into the out tube surrouding, forming drilling hole at last.At the same time, the bit get some vibrate force beneficial to drill hole, which can make soil liquefy and destory the soil original structure. Comparing with other common drilling method, this technology incorporate superiority of compact drilling,air drilling and vibrationg drilling, and have many ascendency such as high drilling efficiency, quick speed of construction, little pollution to environment and stable borehole wall. The Rotary-Percussion-Compact Drilling technology has a wide application and broad prospects for development in shallow geothermal energy exploitation, trenchless and geotechnical anchoring engineering.Bionic engineering is a subject which cross and comprehensive life science and engineering science.The diversity of biological system provides a greet treasure-house for technich research of engineering science.The technich of bionic has become the source for the creation of engineering technology gradually.Bionic nonsmooth surface can reduce the frictionalresistance and adhesion from the soil.The technich of nonsmooth has all ready applied for agriculture machinery and engineering construction machinery successfully and has got good effects. The tangential adhesion and friction is larger because Contact area of the out tube and soil is large dulling Rotary-Percussion-Compact Drilling, and it will be reduced effective after appliance of the bionic nonsmooth technology to out tube. Analysis of the size and distribution of tangential resistance on different surface forms of out tube, the distribution of internal stress of soil, study the performance and variation of bionic nonsmooth out tube when suffering impact load, is important for rational design of bionic nonsmooth out tube, improve the energy efficiency and and drilling efficiency of Rotary-Percussion-Compact Drilling technology, further perfect Rotary-Percussion-Compact Drilling technology.This Paper is rely on scientific project supported by technology department of JiLin province.Analyse research and FEM Simulation analysis the mechanism of reducing friction and adhesion of bionic nonsmooth out tube model in the soil.The emphasis is the simulation test with bionic nonsmooth out tube model outdoor,research the founction of bionic nonsmooth surface reduce resistance and adhesion in the circumstance of impact load.Bionic nonsmooth surface can reduce the contact area with the soil effectively, destory the water membrane of contact interface produced by soil water, so it can reduce the adhesion and friction on Soil-engaging components Substantially. The soil in out tube surrouding is compressed under the action of drill bit, because of soil resilience the out tube suffer large earth pressure; the soil water can form water membrance on surface of out tube, so the out tube suffer large adhesion and friction from soil during drilling.According to bionic nonsmooth surface design bionic nonsmooth out tube, which can reduce the adhesion and friction on out tube from soil effective, improve energy efficiency of the hammer and drilling efficiency of Rotary-Percussion-Compact Drilling technologyBase on the thoery of contact high nonlinear,considering the material nonlinear and geometrical non-linearity when the outer tube injecting into the soil. With the help of ANSYS setting up two-dimension finite element analysis model.The way of contact between out tube and soil is "rigid-befotmarble "contact of face to face, the process of out tube into the soil is simulated by infliction displacement load using the basic Kulun friction law and ostiole expand thoery. The simulated result shows:the smooth out tube and soil are in stable contact and glide condition,the tangential resistance can be the maximum, the contact between the groove-shaped out tube and the soil can be discontinuous obviously.the groove part doesn't contact with the soil,other parts' tangential resistance can be lesser; the convex hull under surface of the convex-shaped put tube contact with the soil so tangential resistance is large,and the convex hull become a cutting piont of the compacted soil, not conducive to the full use of impact energy.Design bionic nonsmooth out tube model and make the outdoor experiment according to existing research data of bionic nonsmooth surface and finite element anlysis: groove-shaped and concave-shaped bionic nonsmooth out tube can reduce the adhesion and friction on out tube produced by soil, for instance, impingement height is 80cm, embedded depth between 20cm to 30cm, the impact energy consumption of groove-shaped out tube can reduce 44.4% compared with smooth out tube. The founction of bionic nonsmooth out tube improvement when the number of nonsmooth unit body increasing, and have increasing trend with the impact energy increasing. Compared with concave-shaped bionic nonsmooth out tube, the founction of groove-shaped bionic nonsmooth out tube is better, and groove-shaped bionic nonsmooth surface is more easy machining on out tube, so groove-shaped bionic nonsmooth surface is More suitable for Structural Optimization of out tube of Rotary-Percussion-Compact Hammer.