| The ice-core of high quality obtained through the ice coring drilling Bing Xin has becomean important method and means to study the past global climatic and environmental changes.The electromechanical core drilling gained the widespread application in the polar drillingengineering because of its advantages of light weight, small energy consumption, convenienttransportation and operation. However, adopting the kind of oil drilling in high temperature ofdeep ice core has disadvantages, such as low drilling efficiency, short cycle and frequent coringdrill accidents. The reason is that the cutting heat generated by the high ice temperature and therotary drilling causes the ice to melt or in the molten state. Ice and melting molten state of theproduced water will freeze again in part of the drill, leading to poor drilling fluid circulationand complex accidents of cards and drilling holes.Based on the theory of metal cutting processing, the ice rotary drilling cutting force modelfounded analyzes and calculates the cutting heat generated in ice rotary drilling. Besides, theinfluential regularities of some factors, such as the drilling pressure, rotation speed, the shearstrength of the ice, cutting depth, bit structure parameters on cutting heat are analyzed. Theresults of calculation show that the effects of these factors on the cutting heat and the cuttingtemperature are different in degrees. The coefficient of friction ice has the greatest influenceupon ice temperature. When the coefficient of friction increases to0.3, ice temperature can beas high as10.91℃. When the temperature of ice is high enough to make ice melt and increasethe risk of the drill bit cutting, the design prefers materials low coefficient of friction. Inaddition to cutting tool rake angle, cutting depth and ice shear strength has a great influence onthe increase of ice temperatureDesign and establishment of ice rotary drilling test bench test design lays the foundation ofequipment for further research on the effects of various factors on the ice rotary drilling cuttingquantity. The test bench can test the effects of drilling pressure, rotation speed, impact drillcutting tool rake angle and low temperature drilling fluid on the cutting temperature. Theexperimental results show that the bit rotary speed increases from80rpm to 140rpm.Experimental results of different ice samples showed that the average temperature risein cutting tool. Cutting natural ice increases from2.57℃to4.27℃, cutting artificial icesamples increases from3.51℃to4.56℃, cutting tool rake angle from15°to30°, whencutting natural ice sample cutting tool decreased from4.39℃to3.36℃and when cuttingnatural ice cutting tool decreased from3.95℃to3.58℃. When comparing experimentalvalues and theoretical values of respectively speed and cutting tool rake angle on cuttingtemperature respectively, we can see that they are basically consistent. When the drillingpressure less than about450N, the experimental values are consistent with theoretical value;and when the drilling pressure increases, the cutting temperature is rising. This is because themodel ignores the effect of cutting tool flank friction heat on cutting temperature, which leadsto theoretical values different from experimental values. Drilling fluid circulation can greatlyreduce the cutting temperature. When the drilling pressure is737N, the cutting of artificial icesample cutting with average temperature is only0.66℃, while the average temperature of thecutting of natural ice samples is about0.7. |
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