Research On The Drilling Mechanism Of Deep Hole Vibration Drilling For Oxygen-free Copper Superconducting Wire Materials

Superconducting technology is a high-tech with great strategic significance,which is widely used in electronic communication,medical treatment,aerospace,electric energy,military equipment and other fields.The application research of superconducting technology is directly affected by the properties of superconducting materials.High-performance copper-based multi-core composite conductors are one of the common superconducting wires.The oxygen-free copper matrix is one of the important parts that affect the performance of multi-core composite conductors with copper as the matrix.Oxygen-free copper substrates are mostly obtained by deep hole drilling.However,due to the characteristics of high plasticity,low hardness,large linear expansion coefficient and high thermal conductivity of oxygen-free copper,there are problems such as difficult chip breaking and poor chip removal in the deep hole drilling process of oxygen-free copper substrate.In order to achieve reliable chip breaking and smooth chip removal,this paper carried out research on deep-hole vibration drilling of oxygen-free copper superconducting wire with the help of low-frequency vibration device.In this study,a mathematical model of low-frequency vibration drilling for gun drilling was established,and the characteristics of thickening,variable speed and vibration shock were analyzed in detail.At the same time,combined with the structural characteristics of the gun drill itself,a mathematical model of cutting force is established,which provides a basis for subsequent prediction of drilling force.In addition,the mechanism of chip breaking is also discussed,and the complete geometric chip breaking and incomplete geometric chip breaking are studied respectively,and the chip length models under their respective conditions are obtained to facilitate the selection of subsequent processing parameters and chip control.Based on the ABAQUS software,the cutting model of the gun drill was established,and the accuracy of the cutting model was verified by comparing the cutting force under ordinary drilling with the mathematical model;through the orthogonal test,the cutting force was used as the evaluation index,and different processing parameters were obtained.And when the speed n=1500r/min,the feed amount is f_r=0.05 mm/r,the amplitude A=0.005mm,and the frequency f=80 Hz,the comprehensive factors are reasonable.The oxygen-free copper material was studied through the actual processing test,and the chip shape,the deviation of the axis of the hole,the surface roughness and smoothness of the inner wall of the hole were compared under ordinary drilling and vibration drilling.Factors such as cutting force,and finally determine the processing parameters and vibration parameters.These results can provide a certain reference for subsequent processing of related materials of similar materials.