型腔拐角铣削加工参数优化与研究

在铣削模具型腔拐角时,拐角处铣削力突变是影响加工质量的重要原因。通过分析刀刃切削轨迹,提出了一种基于单刃等面积切削模型的铣削力参数优化方法。首先根据实际工况下刀刃轨迹路线,计算和分析了拐角处接触角瞬时变化情况,得到单刃等切削面积参数数学模型;然后运用有限元分析软件DEFORM对工件进行动态加工模拟,仿真结果表明:切削力能随着铣削路径实时变化,较传统参数方法该模型设置能够有效的降低拐角处50.20%与36.52%的切削力。并且在VERICUT中进行验证,结果显示优化模型使拐角更加光滑,达到了平稳过渡,为型腔拐角铣削加工工艺参数优化及仿真分析等方面的研究提供了理论依据。     

基于RBF神经网络的花岗岩加工铣削力预测研究

以花岗岩铣削加工中金刚石铣刀为研究对象,对直接导致刀具断裂影响加工效能的关键因素——铣削力进行了研究。针对花岗岩加工铣削力理论公式在实际应用中的局限性,提出了一种采用实验法和神经网络预测相结合的方法。利用实验获得神经网络铣削力预测的建模样本和验证样本以及刀具的断裂极限,利用RBF神经网络对花岗岩加工的铣削力进行了建模预测,通过实验数据验证了该模型的准确性,通过该模型预测获得优选的加工参数,并进行了应用。结果表明该方法有效地提高了刀具的加工效能。     

变截面涡旋盘外圈薄壁齿铣削参数优化及实验研究

针对变截面涡旋盘壁厚变化不均匀,涡旋齿薄壁部位加工表面质量难以控制等加工难点,利用DEFORM软件的铣削模块,建立外圈薄壁齿铣削有限元模型,模拟涡旋齿薄壁部位的三维铣削过程。通过变化模型的铣削速度和铣削深度观察仿真结果中刀具所受到的铣削力的波动情况和其数值大小的变化,对铣削速度和铣削深度进行优化,并用其优化后的铣削参数对实际零件进行加工验证,结果表明:有限元铣削仿真能够非常有效地预测外圈薄壁齿的瞬态加工情况,仿真结果中优化后的铣削速度和铣削深度的铣削力波动明显低于未优化的铣削力波动,实验证明优化后的铣削参数能够有效的改善加工品质。     

MDH80加工中心铣削稳定性研究

为了提高发动机缸体与缸盖结合面的表面加工质量,研究了铣削加工过程中的颤振稳定性问题。进行了刀具—主轴锤击模态试验和铣削力仿真实验,获得了所用刀具的低阶模态参数及铣削力系数。构建了铣削颤振的稳定性叶瓣图,用于指导切削参数的选择和优化。通过该方法可以选取合适的主轴转速和切削深度,避免加工过程中颤振的发生,提高工件表面的加工精度,并对加工刀具及机床本身有保护作用,可提高其使用寿命。     

球头铣刀曲面加工的铣削接触区域建模

机械加工中,铣削力源于刀具与工件在铣削接触区内的相互作用,因此确定铣削接触区域是研究铣削力的基础。针对球头铣刀曲面加工,提出了一种铣削接触区域建模方法。通过定义瞬时加工坐标系和瞬时刀具坐标系,参数化描述曲面加工中球头铣刀与工件之间的相对位姿关系和铣削接触状态。分析了铣削接触区域边界的形成原理,应用解析和数值的方法对边界曲线进行快速求解,建立了铣削接触区域边界曲线模型,并通过加工试验和仿真实例对模型进行验证。结果表明,铣削接触区域边界曲线模型能够高效准确地描述球头铣刀曲面加工中的铣削接触区域。     

T2纯铜高速铣削刀具磨损对表面形貌的影响

目的 满足T2纯铜与日俱增的加工需求,改善T2纯铜的加工质量,探究不同铣削速度下刀具损伤和已加工表面形貌之间的内在联系。方法 根据单因素试验结果,研究铣削速度对于刀具磨损的影响。在磨损刀具铣削力模型和已加工表面应力模型的基础上,从铣削力、刀具损伤形式以及磨损机理出发,分析刀具磨损对于已加工表面质量的影响,解析表面缺陷产生的原因,并通过光学和电子显微镜对磨损后的刀具表面形貌及已加工表面缺陷进行分类表征。结果 当铣削速度较低时,刀具严重的崩刃现象引起了系统铣削力急剧增加,这极大的破坏了铣削系统的稳定性和已加工表面的应力状态,并导致表面粗糙度增大,形成颤振波纹、表面撕裂等加工缺陷。而当铣削速度较高时,由于刀具的损伤较轻,铣削系统相对稳定,已加工表面仍然保持较好的加工质量,特别是铣削速度为600 m/min时,表面粗糙度Sa和Sq的值达到了1.80 μm和2.25 μm,在刀具磨损后仍然分别保持在2.20 μm和3.10 μm左右。结论 在T2纯铜的铣削加工中,提高铣削速度对延长刀具寿命,改善已加工表面质量有积极作用。     

PCD和HTi10刀具铣削CFRP试验研究

针对碳纤维复合材料(CFRP)难加工的特性,文中采用PCD和HTi10刀具进行了CFRP铣削试验,对加工过程中的铣削力、刀具磨损和表面粗糙度进行了分析。结果表明:PCD和HTi10刀具的铣削力和表面粗糙度变化规律一致,均随转速的增大而减小,随进给速度的增大而增大,但PCD刀具的铣削力更小,加工质量更好;与HTi10相比,PCD刀具的铣削力对刀具磨损更加敏感,更适合应用在加工环境较好的条件下。在CFRP加工过程中,粗加工时优选HTi10刀具,精加工时优选PCD刀具,宜选用高转速、低进给的切削参数。     

铣削力建模与计算机仿真

本文综合分析了切削过程中刀具几何参数对端铣铣削力的影响，对铣削力模型进行了修正，建立了适合端铣铣削力计算机仿真的铣削力模型。并对仿真结果与实际测试曲线进行了比较。     

航空薄壁件铣削加工铣削力预测方法研究

铣削加工中铣削力是导致加工变形的直接原因,而航空薄壁件加工中,加工变形是加工误差产生的主要因素.本文以航空薄壁件铣削加工过程的铣削力为研究对象,通过确定铣削力模型和切削系数参数,建立了刚性和考虑刀具工件变形耦合的柔性预测两种模型.在柔性模型中,采用预扭Timoshenko梁单元的刀具/工件独立建模的方法建立有限元模型,利用Python语言在通用有限元软件Abaqus下迭代求解.实验验证表明预测模型具有很高的准确性和有效性.     

微铣削切削力的解析模型分析

针对传统铣削模型不能较好的反映出微铣削刀具因尺寸效应而易受切削力与切削振动的影响效果的问题,建立了微铣削刀具运动轨迹和动态切削厚度模型和考虑刀具磨损的微铣削犁力模型和剪切力模型,通过Deform-2D切削仿真获得了犁力系数和剪切力系数,建立了考虑刀具磨损的微铣削切削力模型。同时通过切削力测试实验与仿真结果进行比对,检验了切削力模型与测试结果的偏差,结果表明该切削力模型预测结果可以较好的反应实际切削力值,可以利用该模型进行微铣削切削力的近似计算,进而验证了模型的正确性与可信度。     

Precise prediction of forces in milling circular corners

Pocket corner is the most typical characters of aerospace structure components. To achieve high-quality product and stable machining operation, manufacturer constantly seek to control the cutting forces in pocket corner milling process. This paper presents the cutting force in corner milling considering the precision instantaneous achievements of tool engagement angle and undeformed chip thickness. To achieve the actual milling tool engagement angle in corner milling process, the details of tool–corner engagement relationship are analyzed considering the elements of tool trajectory, tool radius, and corner radius. The actual undeformed chip thicknesses in up and down milling operations are approached on account of the trochoid paths of adjacent teeth by a presented iteration algorithm. Error analysis shows that the presented models of tool engagement angle and undeformed chip thickness have higher precision comparing with the traditional models. Combined with the cutting force coefficients fitted by a series of slot milling tests, the predicted cutting force in milling titanium pocket with different corner structure and milling parameters are achieved, and the prediction accuracy of the model was validated experimentally and the obtained predict and the experiment results were found in good agreement.     

Process simulation using finite element method — prediction of cutting forces, tool stresses and temperatures in high-speed flat end milling

End milling of die/mold steels is a highly demanding operation because of the temperatures and stresses generated on the cutting tool due to high workpiece hardness. Modeling and simulation of cutting processes have the potential for improving cutting tool designs and selecting optimum conditions, especially in advanced applications such as high-speed milling. The main objective of this study was to develop a methodology for simulating the cutting process in flat end milling operation and predicting chip flow, cutting forces, tool stresses and temperatures using finite element analysis (FEA). As an application, machining of P-20 mold steel at 30 HRC hardness using uncoated carbide tooling was investigated. Using the commercially available software DEFORM-2D™, previously developed flow stress data of the workpiece material and friction at the chip–tool contact at high deformation rates and temperatures were used. A modular representation of undeformed chip geometry was used by utilizing plane strain and axisymmetric workpiece deformation models in order to predict chip formation at the primary and secondary cutting edges of the flat end milling insert. Dry machining experiments for slot milling were conducted using single insert flat end mills with a straight cutting edge (i.e. null helix angle). Comparisons of predicted cutting forces with the measured forces showed reasonable agreement and indicate that the tool stresses and temperatures are also predicted with acceptable accuracy. The highest tool temperatures were predicted at the primary cutting edge of the flat end mill insert regardless of cutting conditions. These temperatures increase wear development at the primary cutting edge. However, the highest tool stresses were predicted at the secondary (around corner radius) cutting edge.     

骨手术中皮质骨铣削力的有限元仿真研究

骨铣削是开颅手术和骨科手术中的必要步骤,铣削力过大会导致铣刀断裂、骨组织周围发生裂纹等问题,从而导致手术过程受到影响。使用ABAQUS仿真软件对四刃立铣刀铣削皮质骨进行有限元仿真并验证模型的正确性。基于仿真模型设计中心复合实验,通过响应面法得到铣削力的二次回归方程,探究铣刀转速、进给量和铣削深度对铣削力的影响。研究结果为骨科手术中合理设定铣削参数提供参考,二次回归方程作为预测模型也为手术中控制铣削力提供可能。     

铝合金6061-T6三维铣削加工有限元仿真及实验

为了获得6061-T6铝合金材料在铣削过程中铣削参数对铣刀切削性能的影响,使用有限元软件AdvantEdge建立有限元模型,研究了铣削深度、铣削宽度和主轴转速对切削力及温度的影响。根据仿真结果分析可得,铣削参数对切削力的影响铣削深度﹥铣削宽度﹥主轴转速;对温度的影响铣削宽度﹥铣削深度﹥主轴转速。通过实验对比,发现仿真结果与实验结果误差不超过30%,且切削力的走向基本一致,说明仿真结果是可信的。     

Prediction of chatter in NC machining based on a dynamic cutting force model for ball end milling

Ball end milling is one of the most widely used cutting processes in the automotive, aerospace, die/mold, and machine parts industries, and the chatter generated under unsuitable cutting conditions is an extremely serious problem as it causes excessive tool wear, noise, tool breakage, and deterioration of the surface quality. Due to the critical nature of detecting and preventing chatter, we propose a dynamic cutting force model for ball end milling that can precisely predict the cutting force for both stable and unstable cutting states because our uncut chip thickness model considers the back-side cutting effect in unstable cutting states. Furthermore, the dynamic cutting force model considers both tool runout and the penetration effect to improve the accuracy of its predictions. We developed software for calculating the cutting configuration and predicting the dynamic cutting force in general NC machining as well as single-path cutting. The chatter in ball end milling can be detected from the calculated cutting forces and their frequency spectra. A comparison of the predicted and measured cutting forces demonstrated that the proposed method provides accurate results.     

涡轮叶片切削参数研究与仿真

为解决涡轮叶片可选加工参数较多、加工质量与效率难以保证的难题,提出一种涡轮叶片的五轴加工工艺。利用解析分析的方法建立切削力理论模型,对比验证切削力经验公式的模型精度。结合工件受力变形有限元模型,选取优化后的切削参数,并利用可视化软件实现对叶片无偏摆点铣与侧铣程序的编制与仿真。可视化仿真结果表明：该加工工艺及参数下,可获得加工精度较高的叶片表面;点铣法加工精度较高,通用性强,与侧铣法相比效率较低。铣削试验结果表明：仿真表面结果与试验表面在变化规律上吻合良好,证明了所提工艺与参数的有效性,提升了涡轮叶片的制造精度与效率。     

复合涂层刀具加工RuT500的铣削力研究及参数优化

为探究和改善蠕墨铸铁RuT500的铣削力，基于单因素试验，选用TiAlN/AlCrN、TiCN/Al₂O₃复合涂层硬质合金刀具对RuT500进行铣削加工，结合响应面探究涂层和铣削参数对RuT500铣削力的影响规律，并进行了铣削参数优化。结果表明：相比于TiAlN/AlCrN复合涂层硬质合金刀具，TiCN/Al₂O₃复合涂层硬质合金刀具铣削RuT500时会产生更大的铣削力；对蠕墨铸铁铣削力影响最显著的因素是背吃刀量，其次是进给量，铣削速度对蠕墨铸铁铣削力的影响程度相对较少；铣削参数交互作用对铣削力的影响具有一定的显著性；取较大的背吃刀量a_p、适当的进给量f和较大的铣削速度v_c时，可以获得较低的铣削力F和良好的加工效率。     

机器人铣削加工让刀误差建模与分析

在机器人切削加工工艺过程中,让刀误差是影响切削加工精度的重要因素之一。以球头铣刀铣削加工为研究对象,视其为准静态运动过程,根据机器人静弹性力学模型和球头铣刀切削力模型,建立了机器人切削过程的让刀误差数学模型。同时,提出了一种基于基因遗传算法的刀具姿态优化方法,以减小切削过程的让刀误差。最后,通过仿真分析了切削参数、刀具姿态和机器人刚度等因素对让刀误差的影响,验证了刀具姿态优化方法的可行性。     

Modelling and simulation of chatter in milling using a predictive force model

A predictive time domain chatter model is presented for the simulation and analysis of chatter in milling processes. The model is developed using a predictive milling force model, which represents the action of milling cutter by the simultaneous operations of a number of single-point cutting tools and predicts the milling forces from the fundamental workpiece material properties, tool geometry and cutting conditions. The instantaneous undeformed chip thickness is modelled to include the dynamic modulations caused by the tool vibrations so that the dynamic regeneration effect is taken into account. Runge–Kutta method is employed to solve the differential equations governing the dynamics of the milling system for accurate solutions. A Windows-based simulation system for chatter in milling is developed using the predictive model, which predicts chatter vibrations represented by the tool-work displacements and cutting force variations against cutter revolution in both numerical and graphic formats, from input of tool and workpiece material properties, cutter parameters, machine tool characteristics and cutting conditions. The system is verified with experimental results and good agreement is shown.