Design Optimization And Experiment Research On The Subglacial Bedrock Drilling Module

One of the most remarkable discoveries made by international scientific expeditions to Antarctica in recent years has been the unexpected discovery of a "second world" at the bottom of the ice sheet.The subglacial environment provides unique information for many natural sciences and interdisciplinary studies.It is of great significance to study the formation mechanism of the Antarctic ice sheet,study the paleoclimate change,predict the future climate evolution,explore the ancient life forms of the earth and study the subglacial geology.In this paper,the domestic and international status of deep subglacial bedrock drilling in the polar region is summarized,and the problems of subglacial bedrock drilling in the polar region are analyzed.Based on the advantages and disadvantages of subglacial bedrock drilling tools at home and abroad,a new design and experimental study of the bedrock coring module of Ice and Bedrock Electromechanical Drill is carried out.A series of studies have been carried out on the theoretical calculation of the power required by the drill,the theoretical calculation of the main structural components,the strength simulation analysis of the gear shaft of the reducer in the driving system,the construction of the motor and reducer testing stand and a series of tests for the driving system,as well as the drilling and coring test of the whole set of bedrock coring module,and the following main conclusions have been drawn.?1?The minimum power required for the drill when drilling in ice,debirs-rich ice and bedrock layers is calculated through theoretical research.In combination with the power consumed by circulating drilling fluid in the pump,the loss of drill rotation in drilling fluid and the loss of friction with the hole wall,etc.And then determine the power required by the motor components of the drill.The selection of relevant motor and the design of gear reduction units are completed,and then the design of the driving system of the bedrock module is completed.?2?Finite element simulation and Modal analysis were carried out on the gear shaft of the two designed gear reduction units through the Static Structural module and Modal module in Ansys Workbench software.By observing the mechanical response of the gear shaft under the rated power of the motor,the stress concentration position of the gear shaft was determined,and the maximum stress and maximum displacement values of the gear shaft under the applied load were obtained.According to the theory of shear strength limit and the range of maximum allowable deformation,the gear shafts are in the safe range,which proves the rationality of the design.?3?A test stand for testing the motor and reducer is designed and built.By carrying out different torque on the motor and gear reducer of the driving system,the variation of the input and output torque,input and output speed,power,efficiency value and motor current value of the reducer is obtained,so as to study the factors affecting the efficiency transmission of the driving part.The test results show that both the planetary reducer and the double-output shaft flange reducer can provide the drilling torque and rotation speed required by the subglacial bedrock drilling.But the transmission efficiency and stability of the double-output shaft flange reducer are higher than that of the planetary reducer.?4?According to the parameter index proposed by the project of the key scientific research instrument and equipment research project of China's Natural Science Foundation--the drilling equipment project of polar deep subglacial bedrock without drill pipe coring,the bedrock coring drill module was designed and processed.The drill includes cable termination,slip ring,anti-torque system,electrical pressure chamber,bedrock module driving circulation system,chips chamber,core barrel and coring bit.The total length of the drill of the subglacial bedrock coring module is 7.0 m,the total weight is 277.6 kg,and the outer diameter of the drill tool is 127 mm.?5?An outdoor laboratory stand was set up to simulate the environment under the polar conditions,which was to test the subglacial bedrock drill.The maximum average mechanical drilling speed of the drill tool is up to 1.3 m/h,and the maximum length of 720 mm granite core samples can be obtained in a single run.The reliability of its drilling ability is proved.Different drilling fluid?aviation kerosene JET-A1 and silicone oil?,different type of water pump?SPK23₂3 and SPK4₁1-11?,different types of coring tube?single coring tube and double-wall coring tube?,and different bedrock gear reducers?the planetary reducer and the double-output shaft flange reducer?were tested.At the same time,the drilling specification parameters are optimized.Through the above tests and improvements,the research and development of subglacial bedrock drilling equipment that can be used in the field of Antarctic has been completed.During the CHINARE 35 th Expedition to the Antarctic,the non-pipe coring equipment was successfully tested in Antarctica.Valuable 198 m ice core samples and 6 cm bedrock core samples were acquired,which proved the design rationality and reliability of subglacial bedrock drill.It also provides important technical support for the future investigation of polar subglacial environment in China.