Drilling Performance Of Gas-bearing Coal And Development Of Core-while-drilling System

Coal seam gas content is an important basic parameter to prevent and control coal mine gas disaster.In view of the enterprise core drill process takes long,working strength higher,and as the "prevention and cure of coal and gas outburst rules" formally implemented,measuring gas content at the time of the working face effect inspection station to increase the number of half,how to quickly drill down coal core as the leading factor of restricting the efficient coal mine safety in production,this paper puts forward a while drilling coring in situ determination of coal seam gas content of technology and equipment,to perfect and abundant coal bed gas content measurement sampling work study,to ensure the safety of coal mine production.This paper in Sihe coal mine gas occurrence law and based on the mechanical properties of coal and rock,based on the theory of coal and rock mechanics properties and broken,with gas of coal gas occurrence conditions of coal or rock related to discuss the influence of rock mechanics properties,and by using the simulation software of ABAQUS drill core process is simulated.According to the simulation results of drilling cores,the stress zone on the coal and rock mass is obviously larger than that on the high speed drilling,and the stress on the coal and rock mass decreases with the increase of the distance from the cutting position of the bit.The larger the weight on bit,the greater the drilling depth per unit time,and the smaller displacement fluctuation when the weight on bit is higher.When the cutting Angle is15°,the high stress area of the bit cutter is smaller than that when the cutting Angle is10° and 20°,so when the bit is designed,the cutting Angle of 15° is beneficial to prolong the bit life.In the process of drilling,the speed and weight on bit can be increased appropriately,so as to ensure the rapidity of coring while reducing the force on the bit.The core components of the coring equipment designed and developed in this paper include a hinged block with a return torsion spring,an open-close drill bit and a coring bit integration.The cutting teeth of the drill bit are polycrystal diamond,and the integration of the coring bit contains a high and low pressure converter.The coring process method is to start the high and low pressure converter through high pressure water during the coring process,which acts on the coring barrel to push out the coring barrel,open the bit block,and drill the progressive core with the drill bit.When the length of the coring barrel is drilled,it is converted into low pressure water,the coring barrel redraws to obtain the coal core,the block closes the drill bit,and the coal core can be extracted by drilling out.The simulation test of core-taking was carried out on the ground to prepare test blocks of coal-like similar materials,and the core was drilled with core-taking equipment.The results of core-taking showed that the samples obtained could basically fill the core-taking barrel,the length of samples was11 mm ? 54 mm,and generally greater than 10 mm,and the core mass of the longest section was 163 g ? 252 g.The integrity of the sample is very high,keeping the complete columnar shape consistent with the core tube.At present,it takes more than four hours to extract a coal core from the depth of a 100 m bedding hole in Sihe Mine.Theoretically,core-while-drilling can save 1/3 ? 1/4 of the time.There are 59 figures,21 tables and 88 references in this paper.