The Study On The Deformation And Destruction Law Of Coal Body Under The Function Of Pick Cutting

The study on the deformation and destruction law of coal body under the function of pick cutting is the important theory and actual subject in rock mechanics and coal industry. It is of a very great importance to make out the deformation and destruction law of coal body under the function of pick cutting for the improvement of mechanized degree of excavating machines and the productivity effect in coal enterprises. In this thesis, the simulation experiment, speckle test, infrared measure and numerical simulation calculating method are used to study the deformation and destruction law of coal body under the function of pick cutting. Some new results have been achieved.The simulation experiment of pick cutting course is carried on the self-made cutting laboratory bench .To change the pick type, the cutting depth etc, so as to observe their influences on the deformation and destruction law of coal body; To adopt octagonal ring dynamometry made by ourselves and signals picking up system of multi-channel, low frequency and high-accuracy so as to monitor the cutting force in coal cutting course; To adopt the high-speed photography method, so as to shoot the cutting course and analyze the law of shaping. It is found that the fluctuation state of the cutting force, side direction force and traction resistance in the same cutting depth are similar. In the same cutting depth, the force employed on the point-attack pick is bigger than that on the knife tooth. When the pick is cutting, the avalanche angle decreases with the increase of cutting depth. The cutting slot decreases with the increase of cutting depth. The coal lumpiness increases with the increase of cutting depth. the electricity exhausting per ton of coal increases with the increase of cutting depth. When the pick cuts into the coal body, the crackles appear on the contact position between coal body and point-attack pick top or knife tooth back. With the heading of pick, the crackles expand quickly. The expanding direction is relevant to the bedding and joint of coal body. At last, it falls off from the coal body.To adopt white light digital speckle correlation method, so as to observe the coal body's deformation and destruction law in pick cutting course. We carry speckle tests separately on coal sample under the function of pick and coal body in simulation experiment. From the digital correlation analysis, we obtain max shearing strain figure and displacement vector graph on coal surface. It is found that there appears a stable deformation localization strip in coal cutting course. Finally it develops into macroscopic crackle. The deformation localization strip is a slantwise strip. When the knife tooth is cutting, the deformation localization develops slowly. But after thedeformation localization, the deformation localization strip is wide and the strain value in strip is a little higher. While the point-attack pick is cutting, the deformation localization develops quickly. But after the deformation localization, the deformation localization strip is narrow and the strain value in strip is a little lower. it is found the destruction of the coal body is mainly the shearing.To make measure and research on the infrared hot image in the deformation and destruction course under the function of pick cutting in order to analyze the deformation and destruction law. To change the pick type, cutting speed, cutting depth, tooth style and measuring position, so as to measure its infrared picture. It is found that there appears a bar of high-temperature district in the direction vertical to cutting direction while knife tooth is cutting the coal. While there is a point of high-temperature district when point-attack pick cuts the coal. The faster the cutting speed is, the more obvious the heat effect will be. In the course of pick cutting, the highest temperature value in temperature field is relative to cutting depth and mechanics characters. The deeper the cutting depth is, the highest temperature is in the temperature field. The bigger the tensile strength, compression stre...