GH4169高温合金铣削力试验研究

针对高温合金材料GH4169的切削加工性差的特点,设计了铣削力测量试验,以研究切削用量、冷却措施等因素对高温合金数控铣削过程产生的铣削力的影响。通过铣削试验分析,得到了切削参数与铣削力的变化曲线,提供了合理的切削参数;利用线性回归方法建立了铣削力经验公式,并通过了试验验证;进行了干切削与乳化液冷却的铣削力对比试验。试验表明选择合理的切削参数和冷却措施能有效抑制铣削力的产生。     

基于变形控制的薄壁结构件高速铣削参数选择

首先对国内外有关研究薄壁件铣削加工变形的文献进行了回顾。然后,对不同切削参数下铣削力变化规律以及因铣削力引起的加工变形进行了理论分析与试验研究,并以此为基础提出了薄壁件高速铣削切削参数选择原则。试验结果表明,采用优化的切削参数不仅使薄壁件加工精度得到了保证,加工效率也大大提高。     

NAK80模具钢铣削加工过程中切削力系数识别

在铣削加工过程中,切削力系数会影响加工表面质量和切削参数的选择。为了得到NAK80模具钢铣削加工切削力系数,建立了适应多种工况下的铣削力系数经验模型,通过正交铣削实验分析了立铣NAK80模具钢时各切削参数对三向铣削力系数的影响规律,并采用偏最小二乘法对铣削力系数的二次多项式经验模型进行识别。利用已建立的切削力模型和得到的铣削力系数对一组切削参数下的铣削力进行仿真分析,得出结果与实际实验对比吻合,验证铣削力模型的正确性。     

铝合金铣削力和温度场的试验研究

应用测力仪和红外热像仪对铝合金切削过程中的切削力和温度信号进行了测试,建立了硬质合金立铣刀切削铝合金的铣削力经验模型,可以有效地指导生产,合理选择切削工艺参数。研究发现,铣削温度随切削参数变化趋势与铣削力同步。切屑的长度、圆弧半径、厚度分别受切削深度、切削速度以及每齿进给量影响而使切屑呈现不同形态。立铣刀在切削铝合金时除切削作用外,还伴随较为严重的塑性变形。另外,分析了切削参数对表面质量的影响。     

淬硬钢模具型腔铣削稳定性分析

在淬硬钢模具型腔铣削加工过程中,模具型腔表面曲线曲率不断的变化会引起实际切削参数的变化,偏离程序中设定的名义参数,各刀齿铣削状态不再完全相同。针对淬硬钢模具型腔曲线铣削过程的未变形动态切削厚度,实际径向切深、刀具-工件接触区域等进行修正,并建立铣削动力学模型,运用全离散法进行铣削稳定性分析,得到铣削稳定叶瓣图;并分析模具型腔形状参数和铣削工艺参数对铣削稳定性的影响,为铣削加工时切削参数的选择,改善工件的表面质量提供依据。     

钛合金高速旋转超声椭圆振动侧铣削切屑特征和刀具磨损研究

难加工材料钛合金在采用传统铣削方式时,随着切削速度的增加,切削力和切削温度都迅速增加,使得切削条件恶化并加速刀具磨损,从而导致刀具过早失效。将超声椭圆振动加工技术引入到高速铣削中,进行了钛合金高速旋转超声椭圆振动侧铣削试验。从切屑特征以及刀具后刀面磨损两个方面研究了高速超声椭圆振动铣削参数匹配对钛合金加工的影响。首先基于高速超声椭圆振动铣削过程中刀具-工件的运动学特点推导出高速超声椭圆振动铣削加工参数与振动参数间的匹配关系,然后利用本实验室自行研制的超声椭圆振动铣削装置进行了不同参数匹配关系下的验证性切削试验。试验结果表明：合理的参数匹配使得超声椭圆振动铣削在高速条件下依然能够实现分离型断续切削加工。相比普通铣削加工,分离型的高速超声椭圆振动铣削能够获得更加微细的切屑,切削热能够被及时地带走;良好的切削条件使得刀具的后刀面磨损均匀而缓慢,从而延长刀具的使用寿命;高速超声椭圆振动铣削能够有效地提高生产效率。     

切削参数对钛合金叶片铣削力的影响分析

进行钛合金叶片加工时,切削力易导致加工变形,影响加工精度和表面质量。因此利用UG软件建立钛合金叶片和切削刀具的三维模型,采用仿真软件建立铣削仿真模型,研究分析了切削参数的变化对铣削力产生的影响。对仿真所得铣削力进行极差分析,判断切削参数对铣削力的影响情况,并通过实际铣削加工试验对比仿真数据验证其准确性和可行性,基于此仿真模型对切削参数对轴向力的影响程度进行了单因素分析。研究结果表明：铣削钛合金叶片时,切削参数对切削力的影响程度从大到小依次为切削速度、背吃刀量和每齿进给量;切削速度与轴向力成反比,每齿进给量和背吃刀量与轴向力成正比。     

铣削加工中切削参数对切削力的影响

切削力是影响零件加工质量和刀具使用寿命的重要因素,而切削力的大小又是和切削参数息息相关的,因此,研究铣削加工中切削参数各因素(切宽、切深和每齿进给量)对切削力的影响有着非常重要的意义.文中通过设计一系列的切削实验,对铣削加工过程中,影响切削力的切削参数各因素进行了分析,从而得出其中的普遍性规律,为铣削加工中切削参数的选...     

钨合金(95WNiCu)铣削参数对铣削力的影响

为研究铣削参数对钨合金工件铣削力的影响规律,设计了单因素实验与正交实验对钨合金进行铣削加工,通过实验数据对铣削力展开影响因素分析以及直观分析,并建立钨合金的铣削力公式.实验结果表明:①铣削力随着主轴转速的增加先增加后减小在增加,随着进给速度和切削深度的增加逐渐增加;②X、Y向铣削参数影响程度主次顺序为切削深度、进给速度、主轴转速;Z向铣削参数影响程度主次顺序为进给速度、切削深度、主轴转速;铣削钨合金对参数的选择应为高转速,小进给速度和小切削深度的加工方式.     

多硬度淬硬钢铣削加工的三维数值模拟

应用斜角铣削过程中的三维热-力耦合模型,对多硬度拼接淬硬钢铣削加工过程进行数值模拟,得到了铣削过程中的切削力、切削温度,在此基础上分析了切削过程中切削速度、切削深度、刃倾角对切削力变化的影响。切削过程的三维数值模拟为多硬度淬硬钢铣削加工过程的工艺参数选择及刀具几何参数的合理确定提供了参考。     

Optimization of machining parameters using genetic algorithm and experimental validation for end-milling operations

Optimization of cutting parameters is valuable in terms of providing high precision and efficient machining. Optimization of machining parameters for milling is an important step to minimize the machining time and cutting force, increase productivity and tool life and obtain better surface finish. In this work a mathematical model has been developed based on both the material behavior and the machine dynamics to determine cutting force for milling operations. The system used for optimization is based on powerful artificial intelligence called genetic algorithms (GA). The machining time is considered as the objective function and constraints are tool life, limits of feed rate, depth of cut, cutting speed, surface roughness, cutting force and amplitude of vibrations while maintaining a constant material removal rate. The result of the work shows how a complex optimization problem is handled by a genetic algorithm and converges very quickly. Experimental end milling tests have been performed on mild steel to measure surface roughness, cutting force using milling tool dynamometer and vibration using a FFT (fast Fourier transform) analyzer for the optimized cutting parameters in a Universal milling machine using an HSS cutter. From the estimated surface roughness value of 0.71 μm, the optimal cutting parameters that have given a maximum material removal rate of 6.0×10³ mm³/min with less amplitude of vibration at the work piece support 1.66 μm maximum displacement. The good agreement between the GA cutting forces and measured cutting forces clearly demonstrates the accuracy and effectiveness of the model presented and program developed. The obtained results indicate that the optimized parameters are capable of machining the work piece more efficiently with better surface finish.     

Selection of an optimal parametric combination for achieving a better surface finish in dry milling using genetic algorithms

In machining, coolants improve machinability, increase productivity by reducing tool wear and extend tool life. However, due to ecological and human health problems, manufacturing industries are now being forced to implement strategies to reduce the amount of cutting fluids used in their production lines. A trend that has emerged to solve these problems is machining without fluid – a method called dry machining – which has been made possible due to technological innovations. This paper presents an experimental investigation of the influence of tool geometry (radial rake angle and nose radius) and cutting conditions (cutting speed and feed rate) on machining performance in dry milling with four fluted solid TiAlN-coated carbide end mill cutters based on Taguchi’s experimental design method. The mathematical model, in terms of machining parameters, was developed for surface roughness prediction using response surface methodology. The optimization is then carried out with genetic algorithms using the surface roughness model developed and validated in this work. This methodology helps to determine the best possible tool geometry and cutting conditions for dry milling.     

Prediction of cutting forces in helical milling process

The prediction of cutting forces is important for the planning and optimization of machining process in order to reduce machining damage. Helical milling is a kind of hole-machining technique with a milling tool feeding on a helical path into the workpiece, and thus, both the periphery cutting edges and the bottom cutting edges all participated in the machining process. In order to investigate the characteristics of discontinuous milling resulting in the time varying undeformed chip thickness and cutting forces direction, this paper establishes a novel analytic cutting force model of the helical milling based on the helical milling principle. Dynamic cutting forces are measured and analyzed under different cutting parameters for the titanium alloy (Ti–6Al–4V). Cutting force coefficients are identified and discussed based on the experimental test. Analytical model prediction is compared with experiment testing. It is noted that the analytical results are in good agreement with the experimental data; thus, the established cutting force model can be utilized as an effective tool to predict the change of cutting forces in helical milling process under different cutting conditions.     

基于动力学约束的端面铣削工艺参数优化

工艺参数优化对提高切削过程的加工效率和加工成本具有重要意义。将铣削系统动力学作为主要约束条件,提出端面铣削工艺参数的多目标优化模型。基于铣削系统动力学分析,得到了综合切削稳定性、工件表面粗糙度、主轴转速、切削力、切削功率等约束的工艺参数多目标优化模型。通过调节权重系数实现优化方向的控制,并采用快速粒子群算法对工艺参数进行优化计算。工艺优化实例及试验表明,采用基于动力学约束的工艺参数优化方法可以获得较好的工艺参数优化结果。     

面向能量效率的数控铣削加工参数多目标优化模型

切削参数是数控加工工艺中的重要组成,切削参数的合理选择能够显著影响到机床能量效率。为提高机床能量效率,分析数控铣削加工的能耗构成特性和加工时段能耗特性,建立数控铣削加工能耗模型,并通过非线性回归拟合获取能耗模型的相关系数,建立了以最高能量效率和最小加工时间为目标的多目标优化模型,采用连续禁忌算法对模型进行优化求解。通过算法优化结果与试验结果进行对比分析,验证了能效模型的有效性。     

基于遗传算法的铣削加工参数模糊优化系统研究

优化铣削参数对于降低铣削加工成本、提高生产率有重要的作用。传统的铣削参数优化模型中，铣削参数和条件约束的匹配取值往往是通过实际加工的经验获得，这种结果具有不确定性和模糊性。文章分析了模糊参数优化的数学模型，根据模糊集合原理将模糊模型转化为一个传统的单目标模糊优化问题，借用IDEF1x方法建立了铣削参数模糊数据库模型，并运用遗传算法（GA）为优化引擎开发实现了模糊优化系统。给出的运行实例表明该优化系统对铣削参数优化具有更好的效果，同时，系统为CAPP优选铣削参数提供了支持平台。     

END MILLING SYSTEM COMPLIANCE AND MACHINING ERROR

Tool deflection resulting from cutting forces places a constraint on the achievable precision and productivity in machining. This paper presents an analytical model of machining error, in terms of part form deviation in end milling due to the elastic compliance of cutting tool. Based on the relationship of local cutting forces and chip thickness, the shear loading and bending moment on the tool cross section are presented in terms of cutter angular position. The tool deflection resulting from the bending moment is then established from the principle of virtual work. The resulting deflection of workpiece and machine tool structure is also considered through shear loading analysis. The expression for machining error is derived as a closed-form function of the machining parameters, cutting configuration, material characteristics, and machine receptance. End milling experiments were conducted to verify the analytical model under various cutting conditions. Error maps are presented to illustrate the effects of process conditions on the achievable part accuracy.     

高速铣削工艺优化研究在数控加工中的应用

以降低数控实践教学成本,提高加工效率为目标,构建了高速铣削加工参数多目标优化方案,合理设定了各类约束条件,并利用复合形法进行优化。具体分析了数控铣削加工切削要素及各类冷却加工形式,对切削速度、径向切削量、背吃刀量等较主要的切削用量的优化选择进行了探讨,为合理选择铣削加工工艺参数提供了参考依据。通过最高生产效率、最低生产成本、综合优化原则构建了最佳切削用量数学模型,为计算结果的准确性取得充实的保障。通过在实例教学中的应用,验证了优化方案的可行性,提高了加工效率,降低了实验材料成本。     

基于模糊分析方法的钛合金插铣加工切削参数优化

合理的切削参数有利于提高刀具的使用寿命和切削效率,因此,进行切削加工过程中的切削参数优化尤为重要。本文以提高钛合金插铣加工效率,减小加工过程中的切削力为目的,对钛合金TC4进行插铣试验。基于切削试验数据,选择切削速度、切削宽度和每齿进给量作为评价因子,以材料去除率与切削力作为评价指标,运用模糊分析方法对切削参数进行综合评价,得出切削参数对综合指标的影响程度从大到小依次为:切削速度、切削宽度和每齿进给量,并实现切削参数的优化,为实际生产加工提供参考依据。     

Optimization of cryogenic milling parameters for aluminum honeycomb treated by ice fixation method

This paper presents the first comprehensive investigation that aluminum honeycomb has inevitable machining defect in milling process, such as deformation, burr, and collapse. Ice fixation method was used to clamp workpieces, and inner-injection liquid nitrogen was employed for a series of cryogenic milling machining. In the machining process, the main machining parameters including in honeycomb orientation, milling width, cutting depth, cutting speed, and feed were executed experimental research. Meanwhile, the machining parameter optimization, range, and significant analysis were adopted to analyze the influence of machining parameters on the machining surface quality, as well as the optimal parameter combination and milling machining surface quality were predicted and verified. The results show that the ice fixation aluminum honeycomb method with cryogenic milling is much advanced than that of conventional ones, and many machining defects are effectively restrained. At the same time, the influence of machining parameters on machining qualities in descending order is cutting depth, cutting speed, honeycomb orientation, feed, and milling width. The minimum roughness value (Ra?=?0.356 μm) of the predicted machining surface is similar to the actual machining result (Ra?=?0.362 μm). It verifies the feasibility of the optimization method. Furthermore, it is proved that the ice fixation + liquid nitrogen cooling method has a positive effect on the high milling quality and implement efficiency for aluminum honeycomb and other difficult-to-machine materials.