【作者】 李鑫；

【导师】 张俊杰；

【作者基本信息】 哈尔滨工业大学 ， 机械工程， 2023， 硕士

【摘要】 轴承钢具有高硬度、高断裂韧性、低热导率等特点,被广泛用于制备航空航天、汽车和能源等产业等领域的精密零部件。在工业生产中通常采用PcBN刀具车削加工制备轴承钢零部件。然而,轴承钢的PcBN刀具车削过程中存在切削力大、刀具磨损严重等问题,制约了轴承钢加工质量和效率的提升。离位激光辅助车削通过在刀具前方施加高能量激光束来软化工件材料,从而有效降低切削力、抑制刀具磨损,可以显著地提升难加工材料的车削加工性能。然而,当前未见PcBN刀具离位激光辅助车削轴承钢的工作报道。首先,激光与轴承钢的相互作用特性未见报道,离位激光辅助车削条件下轴承钢材料的去除特性尚不清楚。其次,当前PcBN刀具车削加工轴承钢的有限元仿真中均将PcBN刀具设为刚体,无法体现刀具内部组织结构、表征其内部应力状态及变化。再次,激光辅助车削工艺参数和PcBN刀具内部组织结构对轴承钢加工质量以及刀具磨损的影响规律未见报道。因此,本文建立了非刚体PcBN刀具离位激光辅助车削轴承钢的有限元模型,结合有限元仿真与实验分析了刀具内部组织结构参数、激光辅助参数对切削力、刀具磨损等的影响规律,具体研究内容如下:首先,建立了非刚体PcBN刀具离位激光辅助车削轴承钢的有限元仿真模型。基于维诺图以及内聚力单元建立了非刚体PcBN刀具,针对传统的非刚体刀具仿真中出现的切削力异常问题进行改进。使用Fortran语言编写高斯光源激光子程序,根据实验条件定义仿真中激光的功率、吸收率、扫描速度等。通过激光预热模型,将不规则的温度场导入车削模型,解决了非刚体PcBN刀具导致的仿真不收敛问题,实现了非刚体PcBN刀具激光辅助车削的有限元仿真。结合不同激光功率下激光加热实验与有限元仿真,标定了轴承钢对实验所用1064nm波长激光的吸收率。其次,研究了PcBN刀具离位激光辅助车削轴承钢的材料去除特性。搭建了PcBN刀具激光辅助车削轴承钢实验平台,开展了激光辅助车削与常规车削的实验对比。通过对比两种不同车削过程中的切削力、刀具磨损、切屑形态以及加工表面质量,证明了激光辅助车削能够有效地改善轴承钢的车削加工性能。通过PcBN刀具车削激光辅助轴承钢有限元车削模型,研究了轴承钢在激光辅助车削条件下的材料去除特性以及切屑形成过程,发现了不同激光参数下切屑形貌的变化趋势,研究了激光参数对切削力、刀具应力的影响规律。最后,研究了PcBN刀具离位激光辅助车削轴承钢的参数影响规律。通过有限元仿真开展了正交试验,研究了激光光斑半径、激光功率和激光扫描速度对轴承钢工件温度场特性的影响规律。通过单因素车削实验,研究了不同激光辅助车削参数对切削力、切屑形貌、刀具磨损的影响规律。开展了不同内部组织结构PcBN刀具的车削实验与有限元仿真,分析了PcBN刀具内部组织结构对切削力、表面质量、刀具磨损等的影响规律。基于优化加工参数实现了表面粗糙度为0.582μm的高质量轴承钢表面。更多还原

【Abstract】 Due to its high hardness,high fracture toughness,low thermal conductivity bearing steel is widely used in the manufacturing of precision components for aerospace,automotive,and energy industries.PcBN tools are commonly used in the industrial process of machining bearing steel.However,PcBN tools face problems such as high cutting forces and severe tool wear during its machining process,which limits the improvement of quality and efficiency of bearing steel machining.Ex-suit laser-assisted turning,which applies a high-energy laser beam to soften the workpiece material in front of cutting tool,offers significant enhancements in cutting performance for difficult-to-machine materials by effectively reducing cutting forces and suppressing tool wear.However,there is no report on the ex-suit laser-assisted turning of bearing steel using PcBN cutting tools.Firstly,the interaction characteristics between laser and bearing steel have not been thoroughly investigated,and the material removal mechanisms of bearing steel under laser-assisted turning conditions are not well understood.Secondly,current finite element(FE)simulations of PcBN cutting tool turning processes for bearing steel treat the PcBN tool as a rigid body,without the consideration of its internal structural composition and internal stress state evolution.Furthermore,there is a lack of research on the effects of laser-assisted turning process parameters and the internal tool structure of PcBN cutting tools on machining quality and tool wear for bearing steel.Therefore,this thesis aims to establish a FE model for laser-assisted turning of bearing steel with a non-rigid PcBN cutting tool.By combining FE simulations and experiments,this research analyzes the impact of laser-assisted parameters and internal tool structure parameters on cutting forces,and tool wear.The main research contents are listed as follows:Firstly,a FE simulation model is established to explore the ex-suit laserassisted turning of bearing steel with a non-rigid PcBN cutting tool.The non-rigid PcBN cutting tool is developed based on the Voronoi and cohesive zone elements,addressing the issue of abnormal cutting forces encounters in conventional nonrigid tool simulations.In order to define the laser power,absorption rate,scanning speed,and other parameters in the FE simulation,a Fortran subroutine for implementing a Gaussian laser in the FE model is established.By integrating the laser pre-heating model,the turning model is able to incorporate an irregular temperature field,resolving the convergence challenges arising from the non-rigid PcBN tool,and enabling the FE simulation for laser-assisted turning with nonrigid PcBN tool.The absorption rate of bearing steel for the 1064 nm wavelength laser used in the experiments is calibrated by combining laser heating experiments under different laser powers and FE simulations.Secondly,the material removal characteristics of bearing steel during ex-suit laser-assisted turning with PcBN cutting tools were investigated.An experimental platform is set up to perform laser-assisted turning of bearing steel with PcBN cutting tools,and comparative experiments are conducted between laser-assisted turning and conventional turning.A comprehensive analysis of cutting forces,tool wear,chip morphology and surface quality is carried out to evaluate the performance of both turning processes.The results clearly demonstrate the significant enhancement in the machining performance of bearing steel achieved through laser-assisted turning.The material removal characteristics and chip formation process under laser-assisted turning conditions are examined by using the FE model of laser-assisted turning with PcBN cutting tools on bearing steel.The study identifies the variation trends in chip morphology,cutting forces and tool stresses under different laser parameters.Finally,the influence of parameters in the ex-suit laser-assisted turning with PcBN cutting tools on bearing steel is investigated.FE simulations are carried out to investigate the effects of laser radius,laser power,and laser scanning speed on the temperature field under the design of orthogonal experiments.Single-factor turning experiments are performed to investigate the effects of different laserassisted turning parameters on cutting forces,chip morphology and tool wear.Turning experiments and FE simulations using PcBN cutting tools with different internal structures were carried out to analyze the influence of internal tool structure on cutting forces,surface quality and tool wear.A high quality machined surface of bearing steel with a surface roughness of 0.582μm is achieved by using the optimized parameter in the ex-suit laser-assisted turning with PcBN cutting tools.更多还原