304不锈钢超声辅助切削研究

通过霍普金森杆试验确定304不锈钢的本构模型,在ANSYS软件中建立工件和刀具模型,设置切削加工参数和超声参数,进行超声辅助车削仿真试验得到相应切削力,并与理论模型进行比对,确定仿真试验的正确性。分析仿真数据,利用单因素分析法研究超声辅助切削过程中超声振幅、切削速度、切削深度和进给量对切削力的影响。结果表明:在相同切削参数下,相比于传统车削,超声辅助切削304不锈钢可有效降低切削力;随着超声振幅的增大,切削力先变小后变大;超声振幅A=23μm时,切削力最小。在给定的车削加工参数范围内、保证加工效率和工件质量的前提下,超声辅助车削304不锈钢最优车削加工参数为:超声振幅A=23μm,切削速度v_c=21m/min,切削深度a_p=0.1mm,进给量f=0.08mm/r。     

AISI 304不锈钢的车削加工

针对AISI 304奥氏体不锈钢的特点,分析了AISI 304不锈钢材料的物理性能和切削加工性能,从刀具材料、切削用量和冷却液的选择等方面研究了AISI 304不锈钢车削加工的影响因素,通过合理选择和优化相关参数等方法有效解决了AISI 304不锈钢的加工难题,获得了较好的车削加工效果,提高了生产效率。     

车削AISI420不锈钢切削力预测模型构建

为了进一步研究AISI420不锈钢的切削机制,在Third Wave Advant Edge中建立车削有限元模型,进行车削加工仿真模拟,并对实验数据进行回归分析,得到三向切削力的预测模型。结果表明:车削力预测模型拟合度较好,回归分析效果显著,有较高的置信度,可为AISI420不锈钢的切削研究提供理论参考。     

基于DEFORM的304不锈钢铣削数值模拟

针对不锈钢材料的难加工性,为进一步研究切削机理,建立了一个简化的铣削模型。利用DEFORM有限元仿真软件对304不锈钢的铣削加工过程进行了仿真,通过径向切深、轴向切深、每齿进给量及切削速度的正交化参数条件模拟了铣削力的大小分布,并将模拟结果与实验结果进行了比较分析。结果表明仿真值与实验值较为相符,此模型能够很好地预测铣削力,为研究铣削力的影响因素、优化加工参数及不锈钢材料切削机理奠定了基础。     

铝合金7075车削温度的有限元研究

切削温度对切削加工有很大的影响。在Deform-3D中建立了铝合金7075的车削有限元模型,以切削用量为因素设计了正交试验方案,对车削加工进行仿真研究。通过数据处理,得到了切削用量对切削温度的影响程度、最优水平组合及影响的显著性。依据正交试验结果,建立了车削温度预测模型并进行了拟合优度和回归显著性检验,结果表明:车削温度预测模型和实验数据的拟合优度非常好,回归方程效果显著。     

大型薄壁回转结构件加工变形预测研究

针对大型薄壁回转体车削过程中加工变形大,影响发动机安装和使役性能的突出问题,基于ABAQUS软件有限元仿真及其二次开发技术,开发了具有切削力载荷动态施加、依次卸载关键功能的有限元仿真辅助软件,实现了大型薄壁回转结构件全尺寸、完整结构的车削加工变形有限元仿真预测;并针对两种径向辅助支撑方式,分析了切削力对工件内、外圆跳动误差的影响规律;通过仿真计算结果和试验结果对比,验证了加工变形有限元预测的准确性;论文提出的相关技术为控制大型薄壁回转体加工变形、优化装夹方式提供了技术支持。     

车削钛合金切削参数对切屑形态的影响

钛合金材料具有塑性好、屈服强度高、耐高温、耐腐蚀等特点,在兵器装备、医疗器械、航空航天、核电设备等领域都有着广泛应用,同时钛合金也是一种难加工材料,这是由于钛合金材料的导热性差,弹性模量小,使它本身的加工性能特别差。由于钛合金材料的优良特性,钛合金材料在各领域得到广泛应用。为了改善钛合金材料难加工的特点,更好地推动钛合金材料的发展,研究车削加工钛合金的切削特性是非常必要的。通过ABAQUS有限元仿真软件对钛合金TC4进行有限元仿真,对车削钛合金进行加工,通过结果分析切屑形态,再利用车削加工试验进行验证,采用与仿真相同的试验参数进行试验,得出试验结果:应选择较大的刀具前角和后角、适中的切削速度以及较小的进给量。     

钻削加工的三维建模及可视化

基于金属切削加工的有限元仿真和可视化技术,结合奥氏体不锈钢的钻削试验,对钻削加工过程进行了三维建模,对钻削条件、刀具参数与切削力、切削温度的关系进行了有限元仿真分析,并将仿真预测结果与钻削试验的实测结果进行了比较。     

高强度材料车削机械断屑器设计分析

针对304奥氏体不锈钢为代表的典型高强度、车削加工难断屑材料,设计了一种具有主动机械动力的切屑二次折断装置.断屑装置由直流电机提供动力,在切屑流向断屑器时,通过旋转的内断屑刀和固定的外断屑刀共同作用折断切屑.实验和仿真对比,分析了304奥氏体不锈钢在不同切削用量下使用该断屑器辅助车削和干切削时切屑形态,以及在各切削用量下使用断屑器辅助车削的优化效果,并得出断屑器取得良好断屑效果及最大程度降低前刀面温度的优化切削参数.验证了其在不同切削用量下均能够稳定可靠地断屑,避免了切屑缠绕问题,降低了刀具车削时前刀面的温度并提高了生产效率.     

水蒸气冷却润滑切削304不锈钢的试验研究

为实现304不锈钢的绿色切削,以过热水蒸气作冷却润滑介质,用Al2O3-TiC复相陶瓷刀具对304不锈钢进行单因素切削试验.试验结果表明:与干切削相比,用过热水蒸气冷却润滑切削时主切削力减小了6％ ～17％,加工表面硬化程度降低了3％～6％,并具有较高的加工表面质量.根据试验结果和冷却润滑作用机理分析可知,过热水蒸气具有较好的冷却润滑作用,且廉价无污染,有望实现304不锈钢的绿色切削.     

Experimental investigation of surface roughness and cutting ratio in a spraying cryogenic turning process

Abstract

Surface roughness is one of the most common criteria indicating the surface finish of the part, which depends on various factors including cutting parameters, geometry of the tool, and cutting fluid. One of the goals of using cutting fluids in machining processes is to achieve improved surface finish. In addition to high costs, commonly used cutting fluids cause dermal and respiratory problems to the operators as well as environmental pollution. The present article aims at investigating the effect of spray cryogenic cooling via liquid nitrogen on surface roughness and cutting ratio in turning process of AISI 304 stainless steel. Through conducting experimental tests, the effects of cutting speed, feed rate, and depth of cut on surface roughness and cutting ratio have been compared in dry and cryogenic turning. A total number of 72 tests have been carried out. Results show that cryogenic turning of AISI 304 stainless steel reduces surface roughness 1%–27% (13% on the average), compared to dry turning. The obtained results showed that the cutting ratio in cryogenic turning is averagely increased by 32% in comparison with dry turning, also that chip breakage is improved in cryogenic turning.     

A formability index for the deep drawing of stainless steel rectangular cups

The effects of process parameters on the formability of the deep drawing of rectangular cups made of SUS304 stainless steel were investigated by both the finite element analysis method and the experimental approach. A statistical analysis was employed to construct an orthogonal chart which reflects the effects of the process parameters and their interactions on the formability of rectangular cup drawing. The material properties and the forming limit diagram (FLD) of SUS304 stainless steel were obtained from the experiments conducted in the present study and were employed by the finite element simulations. In the finite element analysis, the strain path that led to fracture in the drawing process was examined and the failure modes caused by different process parameters were also identified. With the help of statistical analysis, a formability index for the deep drawing of SUS304 stainless steel rectangular cups was constructed and the critical value of the formability index was determined from the finite element simulation results. The actual drawing processes of rectangular cups were also performed in the present study. The validity of the finite element simulations and the formability index were confirmed by the good agreement between the simulation results and the experimental data. The formability index proposed in the present study provides a convenient design rule for the deep drawing of SUS304 stainless steel rectangular cups.     

基于黏结-滑移摩擦模型的304不锈钢切削力仿真研究*

通过预测加工304不锈钢时产生的切削力,从而对切削参数和刀具几何参数进行优化,是提高304不锈钢的加工精度、切屑控制及保障刀具寿命的基础。建立304不锈钢切削仿真模型,为提高模型的精确性,选择Johnson-Cook本构方程和黏结-滑移摩擦模型。结果表明：采用黏结-滑移摩擦模型的切削力预测结果更为准确,表明相对于纯剪切摩擦与库仑摩擦模型,黏结-滑移摩擦模型能更准确地描述刀-屑摩擦特性。展开不同参数下的切削力研究,研究发现：切削力随着刀具前角、后角和切削速度的增大而减小,随切削刃钝圆半径和切削厚度、宽度的增大而增大,其中切削宽度、厚度及前角对切削力大小影响较大。研究结果为304不锈钢切削效率的提高和切削机制的研究提供了理论依据。     

304不锈钢紧凑拉伸裂尖应力强度因子有限元分析

304不锈钢结构在工程应用中经常发生疲劳断裂.利用有限元数值模拟方法对304不锈钢制成的紧凑拉伸试样进行二维分析,通过J积分计算应力强度因子.使问题满足平面应力条件,通过对数据处理,分析载荷大小和裂纹长度对应力强度因子的影响.把有限元计算的结果和经验公式对比,分析误差及有限元方法的可行性.     

Analysis of pulsed Nd:YAG laser welding of AISI 304 steel

Pulsed laser welding of AISI 304 stainless steel plate was simulated using commercial finite element software to determine the optimal welding conditions. Due to geometric symmetry, only one plate was modeled to reduce the simulation computation time. User subroutines were created to account for a moving three-dimensional heat source and to apply boundary conditions. The material properties such as conductivity, specific heat, and mass density were determined as functions of temperature. The latent heat was considered within the given temperature range. The three-dimensional heat source model for pulsed laser beam butt welding was designed by comparing the finite element analysis results and experimental data. This successful simulation of pulsed Nd:YAG laser welding for AISI 304 stainless steel will prove useful for determining optimal welding conditions.     

Prediction of surface roughness and cutting zone temperature in dry turning processes of AISI304 stainless steel using ANFIS with PSO learning

This paper presents an approach for modeling and prediction of both surface roughness and cutting zone temperature in turning of AISI304 austenitic stainless steel using multi-layer coated (TiCN?+?TiC?+?TiCN?+?TiN) tungsten carbide tools. The proposed approach is based on an adaptive neuro-fuzzy inference system (ANFIS) with particle swarm optimization (PSO) learning. AISI304 stainless steel bars are machined at different cutting speeds and feedrates without cutting fluid while depth of cut is kept constant. ANFIS for prediction of surface roughness and cutting zone temperature has been trained using cutting speed, feedrate, and cutting force data obtained during experiments. ANFIS architecture consisting of 12 fuzzy rules has three inputs and two outputs. Gaussian membership function is used during the training process of the ANFIS. The surface roughness and cutting zone temperature values predicted by the PSO-based ANFIS model are compared with the measured values derived from testing data set. Testing results indicate that the predicted surface roughness and cutting zone temperature are in good agreement with measured roughness and temperature.     

Study of Residual Stress Distribution in the Machined Stainless Steel Components

The demand for high quality and fully automated production, coupled with advances in alloy development, focuses attention on the surface condition of products, especially the residual stresses on the machined surface because of its effect on component performance, longevity, and reliability. Although stainless steel is an important, material with wide application, it is not easy to obtain favorable surface condition, due to its sensitivity to thermal and mechanical operations. In order to obtain favorable surface conditions in a stainless steel component, it is necessary to have practical data which include information concerning tool wear, surface roughness and surface residual stress. In the research toward developing a machinability chart which can provide suitable cutting parameters for the high production rate and good quality surface, and can be used in computer controlled machining tools, surface residual stress distributions in the turning process for stainless steel were studied. Austenitic 304 stainless steel bars were selected as the workpieces and uncoated carbide tools were used in the tests. The obtained results will show residual stress conditions on the machined stainless steel components varying according to cutting conditions.     

大进给铣削沉淀硬化不锈钢刀具失效分析及切削参数优化

针对大进给硬质合金刀具铣削沉淀硬化不锈钢（05Cr17Ni4Cu4Nb）寿命短、效率低的问题,采用单因素法和正交试验法开展刀具磨损试验,并进行回归分析,得到了刀具寿命经验公式。利用有限元仿真方法获得了切削力、刀具切削刃温度和应力场分布情况,结合磨损测量结果及磨损形貌分析了刀具的失效机理。根据有限元仿真结果和刀具寿命经验公式,综合考虑切削效率和刀具磨损,运用等寿命-效率曲面响应法进行切削参数优化,得到了刀具的最佳切削参数及在该切削参数下刀具的寿命。     

Analytical modelling of microstructure changes in the machining of 304 stainless steel

In the machining of hard machined materials, microstructure changes in the machined surface must be taken into account to improve product performance. Therefore, a large number of experimental and finite element method investigations have been carried out to investigate these microstructure changes. However, until now, only a few studies have reported the analytical modelling of microstructure changes. This paper presents a hardness-based analytical model that accounts for both mechanical and thermal effects in predicting microstructure changes during the machining of 304 stainless steel. The model was also validated for a range of cutting speeds, feed rates, and wear widths. The predicted results are in good agreement with the experimentally measured results. Thus, with the analytical model, an accurate prediction of microstructure changes is achieved, which reduces experimental expense and finite element method computational time.