Research On Symmetrical Deep Hole Machining Tool System Based On The Hydrodynamic Lubrication Mechanism

At present,most deep hole cutting tools are guided by guide block,but the asymmetric structure of tool,unbalance of centrifugal force and radial force will make the tool vibrate.The heat generated by friction between the guide block and the hole wall will also worsen the working environment of the tool and reduce the service life of the tool.When machining a deep hole,it is easy to bend and deform because of the slender and long drill pipe,which results in a large cross-section angle at the edge of the tool and poor guidance,which leads to the deterioration of the surface quality and straightness of the machined hole.In order to solve these problems,a new guiding structure based on hydrodynamic lubrication is designed,in which the wedge is machined on the drill pipe for guiding.When the cutting fluid enters the small gap from the large gap,the corresponding oil film pressure is produced.When the drill pipe is not eccentric,the oil film pressure produced by the cuneiform is balanced,and the drill pipe is fixed on the ideal axis to realize self-centering.When the drill pipe is eccentric,the corresponding oil film pressure will be generated between the wedge and the machined hole wall.The force of oil film pressure will push the drill pipe close to the ideal axis to achieve the purpose of self-correcting and guiding.Between the drill pipes,the drill pipe and the tool,even the clamping device of the drill pipe and the drill pipe are connected and fixed by thread.Multiple cuneiform structures can be set up to form multi-fulcrum support guidance and improve the stiffness of drill pipe system.In order to avoid friction between guide block and machined hole wall and vibration caused by asymmetry of tool,a new double-edge symmetrical tool is designed on the basis of the guide structure instead of guide block guidance.Because of the use of double-edge drilling,a new kind of double-edge symmetrical tool is designed,which can avoid the friction betweenthe guide block and the machined hole wall.It can improve the feed of the tool and the machining efficiency of deep hole.The concrete structure is similar to the form of BTA drill,through the combination of step axial chip separation and small sleeve material,the drilling is completed.Based on the comparison of the existing deep hole machining systems,a suitable DF deep hole machining system is recommended according to the guiding structure,the tool structure and the demand for chip removal.According to the simple analysis of the mechanism of negative pressure chip extraction,it is concluded that the chip removal capacity of the system can be improved by increasing the pressure and flow rate of cutting fluid.Finally,the double fulcrum guiding structure is simulated and analyzed by using Fluent software,and the guiding ability of the guiding structure in machining deep holes is verified.