Research On Chip Morphology Control And Fracture Morphology Of 50 Steel Internal Chip Removal Deep Hole Drilling

Deep-hole processing technology occupies an important position in the equipment manufacturing industry.With the development of science and technology,deep-hole processing technology is no longer limited to the military industry,but is more used in civilian manufacturing.Deep hole machining mainly solves the problem of chip breaking and chip removal.The range of existing main processing parameters has been obtained through a large number of experiments.To change the tool parameters or workpiece material,it is necessary to re-explore the value range of processing parameters,which lacks theoretical analysis and prediction.This article takes Ti N cemented carbide BTA drill(Beisner internal chip removal deep hole drill)drilling 50~#steel as the research object,and analyzes in detail the chip fracture morphology and chip morphology of the side teeth,intermediate teeth and center teeth under different process parameters.content include:Based on the basic cutting theory,two-dimensional and three-dimensional curling models of chips in deep hole machining are constructed.The data shows that the model can be used to analyze the spiral outer diameter changes of spiral chips in three-dimensional crimping under different processing parameters;analyze the spiral trajectory of free crimping chips and the formation process of hole bottom obstacle chips;analyze the three factors of hole bottom obstacle chips The force characteristics of a typical cross-section,and five breaking methods for chip breaking are predicted.Through the deep hole cutting test,the changes of post-processing parameters such as chip breaking rate,chip width,chip length,chip compression rate and so on are analyzed in detail.The test found that the chip width is basically unchanged during the cutting process;when the chip compression ratio CCR<10,the cutting energy consumption is significantly reduced;when the chip breaking rate CFR<10,the chip can be broken smoothly.According to the chip fracture morphology,the fracture form of each tooth chip is analyzed in detail.The test found that the chip fracture morphology in deep hole machining can be clearly divided into three areas;The inside of the chip undergoes a compression unloading and stretching process,while the outside of the chip undergoes a stretching unloading and compression process.Shear slip occupies an important position in the entire chip formation process.The cutting speed increases,causing small cracks in the middle area to converge;As the feed rate increases,the fracture morphology transitions from dimple fracture to quasi-cleavage fracture.Preliminarily determined the reasonable value range of the processing parameters of deep hole:rotation speed is 200～380r/min;side tooth and middle tooth feed rate is 0.18mm/r～0.20mm/r;center tooth is 0.15mm/r～0.18mm/r.In summary,the way of chip curling and breaking in deep hole machining is different from ordinary machining.The ideal chip crimping and breaking process in deep hole machining is free crimping,chip breaker obstruction,spiral crimping,and hole bottom obstruction type breaking.Based on the"adiabatic shear model"and"preload-unload-reload model"of sawtooth-shaped chips in high-speed cutting,this paper proposes a ductile shear model and systematically analyzes the chip fracture surface characteristics of deep hole machining.