基于WTK软件的切屑形成与折断过程虚拟现实的研究

采用虚拟现实 (VR)技术 ,以 VC++6 .0和虚拟现实软件 World Tool Kid9.0为开发平台 ,以切屑折断数学模型为理论研究基础 ,对于给定的切削参数 ,实现了三维复杂槽型刀片在车削加工时切屑形成与折断过程的虚拟现实 ,预报了切屑折断过程 ,从而可评估切削刀片槽型设计质量 ,优选槽型 ,有利于缩短刀片设计和制造周期     

A knowledge-based approach for designing effective grooved chip breakers — 2D and 3D chip flow,chip curl and chip breaking

This paper presents details of a knowledge-based approach for designing effective grooved chip breakers for two- and three-dimensional chip flow, curl and breaking. The design criterion used in formulating this new approach is effective chip breaking at minimum power consumption. This work was aimed at achieving the optimum groove parameters and the best utilisation of groove profile under varying machining conditions. A systematic knowledge-pool was established from a series of well-designed machining experiments which form four knowledge databases (reference database, grooved chip breaker database, natural contact length database and 3D chip flow database). This paper shows how the chip breaker design parameters can be estimated for effective chip breaking at reduced power consumption. The basic tool design strategy presented in the paper also includes some guidelines, for cutting tool designers, highlighting the need for implementing a scientific approach for designing a chip breaker against the current practice of try and see methods.     

超精密车削切屑形成过程的试验研究

超精密车削中的各种物理现象，如切削力、刀具磨损以及加工表面质量等问题，都是以切屑形成为基础的。而生产实践中出现的许多问题，如振动、卷屑和断屑等，又都与超精密切削过程密切相关。选用的材料种类和切削条件不同，可生成不同形态的切屑。文章提出了一种研究切屑形成过程新的试验方法，利用该方法能够得到金刚石车削时高清晰的金属材料塑性流动图像。     

Investigation of the direction of chip motion in diamond turning

Management of the chips generated in diamond turning is often critical since contact between chips and the workpiece can result in superficial damage to the finished surface. Controlling chip motion is not a trivial process as the proper positioning of an oil or an air stream requires an understanding of the dynamics of a diamond turned chip and the machining parameters that affect it. Previous work [1] introduced the chip curvature parameter, χ, which is useful in predicting chip radius of curvature over a wide range of cutting speeds, depths of cut, tool geometries and workpiece material properties. To control chip motion, however, an understanding of the direction chips leave the tool/workpiece interface must also be obtained. Cutting experiments were performed investigating the influence of cutting speed, depth of cut, feed rate, tool path angle, tool geometry and tool orientation on the directional characteristics of the motion of diamond turned chips. Flow angle measurements obtained during cutting were found to remain within ± 10° of predictions from a simple geometrical model originally proposed for conventional machining.     

高速铣削淬硬钢时切削载荷平稳化研究

和传统的铣削加工相比,高速铣削淬硬钢更需要稳定的切削载荷,以尽可能减少刀具碎裂和过度磨损。本研究借助三向压电石英测力仪,使用TiAlN涂层球形端铣刀,在13500 r/min的转速下,对淬火45#钢(47HRC~48HRC)进行了高速铣削试验,建立了高速铣削下的多项式切削力试验模型,模拟了以恒定切削力为目标、优化进给率的加工实例。结果显示,稳定的切削载荷能有效地提高加工效率,避免刀具剧烈磨损。     

基于人工神经网络的车削切屑形态预测动态建模及实时仿真

针对数控加工中切屑形成过程的监控问题,在基于实时工况智能监控平台上,通过研究切屑形态预测的神经网络动态建模方法,建立了切屑形态预测仿真动态模型.并根据切屑空间运动轨迹的数学模型,建立了切屑三维造型模型,在虚拟现实环境中实现车削过程的切屑实时动态仿真.     

聚晶金刚石刀具的断屑槽尺寸参数设计

为解决聚晶金刚石(PCD)刀具在铝合金材料切削过程中的切屑缠绕问题,在PCD刀具的前刀面上设计了断屑槽.通过对切屑受力过程和断屑槽断屑机理的分析、切削几何关系的推导和有限元切削仿真实验,提取了5个PCD刀具断屑槽参数,即棱带宽度、倾角、反屑角、槽宽和反屑面转角.建立了PCD刀具断屑槽棱带宽度和反屑角的计算公式;改进了槽...     

Parametric tool wear estimation solution of HSC appropriate machining

New strategies are used in manufacturing enterprises due to global competition. High-speed cutting offers a very appropriate opportunity to reduce run times since the high cutting speeds and feed rates involved permit the reduction of production times and minimise rework. There are, however, difficulties in judging tool wear [1]. This paper analyses the formation mechanism of tool wear and presents a complete solution to calculate wear using a ball end cutter for high-speed cutting. Chip geometry generated to calculate tool wear is affected by machining conditions such as turning speed, cutting depth and geometries of tool and work piece which in turn determine the key parameters of chip sections such as length of cut and mean chip thickness. An improved algorithm and a knowledge-based decision model developed to calculate effective tool contact are also discussed to help reduce calculation time and improve calculation efficiency. The calculation results include output form and a 3D wear model showing wear data distributed on the tool contour.     

Chip Formation Mechanism of Inconel 718:A Review of Models and Approaches

Inconel 718,a nickel,chrome and iron alloy,has special advantages,such as high-temperature strength,thermal resistance and corrosion resistance,which facilitate wide usage in the aerospace industry,especially in the hot sec-tions of gas turbine engines.However,machining this alloy is correlated closely with the material's inherent properties such as excellent combination of strength,hardness and toughness,low thermal conductivity and the tendency to adhere to cutting tools.This nickel alloy also contains inclusions of hard abrasive carbide particles that lead to work-hardening of the workpiece material and thus abrasive wear of the cutting tool.That is,the machining of Inconel 718 is always influenced by high mechanical and thermal loads.This article reviews the chip formation mechanism of Inconel 718.One of the main characteristics in machining of Inconel 718 is that it will produce serrated or segmented chips in a wide range of cutting speeds and feeds.Existing studies show that the chip serration or segmentation by shear localization affects the machined surface integrity,and also contributes to the chip's evacuation and the auto-mation of machining operations.Thus,research conclusion indicates that the serrated or segmented chip phenom-enon is desirable in reducing the level of cutting force,and detailed analysis of models and approaches to understand the chip formation mechanism of Inconel 718 is vital for machining this alloy effectively and efficiently.Therefore,this article presents some summaries on the models and approaches on the chip formation in machining of Inconel 718.     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

Prediction of chip flow angle in orthogonal turning of mild steel by neural network approach

Improvement of chip control is a necessity for automated machining. Chip control is closely related to chip flow and it plays also a predominant role in the effective control of chip formation and chip breaking for the easy and safe disposal of chips, as well as for protecting the surface-integrity of the workpiece. Although several ways to predict the chip flow angle (CFA) have been subjected in some researches, a good approximation has not been achieved yet. In this study, using different indexable inserts and cutting conditions for turning of mild steel, the chip flow angles were measured and some of the collected data from this experimental study were used for training with a two hidden layered backpropagation neural network algorithm. A group was formed from randomly selected data for testing. The chip flow angle values found from multiple regression, neural network (NN) and studies of previous researchers under the same turning conditions of the present study were compared. It has been seen that the best prediction was obtained by neural network approach.     

车铣复合加工的切屑形态分析

通过对车铣复合加工高强度钢的不同切屑形态分析表明,随轴向进给量和切削深度的增加,切屑变长.在建立车铣切削变形模型的基础上,分析了车铣切屑的形成机理.切削层金属裂纹的周期破裂和形成是车铣切屑形成的根本原因.     

高温合金振动钻削断屑实验研究及机理分析

对振动钻削理论进行了分析,建立了振动钻削时断屑的数学模型,利用自制的振动钻削实验装置,采用不同的振动钻削参数进行高温合金振动钻削试验,对轴向振动钻削的断屑效果以及轴向钻削力和扭矩进行了研究,分析了各加工参数对加工过程的影响,发现振动钻削力随钻削参数的变化比较平稳,在大进给量或高转速状态下,振动钻削的钻削力比普通钻削力小得多。通过比较振动钻削与普通钻削所得切屑可知:振动钻削有利于断屑,切屑体积小,排屑顺畅。     

国产常用可转位刀片断屑槽断屑性能的研究

在前人工作的基础上,对常用的可转位车刀片断屑槽的断屑性能进行了研究。文中综合考虚了加工精度和刀具寿命等问题,并且涉及到不同的刀具材料。本文研究的内容为可转位刀片断屑槽的合理选用及新型断屑槽的设计和开发提供了依据。     

Investigation and prediction of chip geometry in diamond turning

Management of the chips generated in diamond turning is often critical, because contact between chips and the workpiece can result in superficial damage to the finished surface. Controlling chip motion is not a trivial process as the proper positioning of an oil or air stream requires an understanding of the dynamics of a diamond turned chip and the machining parameters that affect it. Work has been performed to investigate the effects of cutting speed, depth of cut, tool geometry, tool wear, and workpiece material properties on chip motion and geometry. Utilizing radius of curvature data from cutting experiments, a parameter has been proposed that can be used to predict chip radius of curvature for a wide range of machining conditions. This chip curvature parameter, χ, exhibits a power law relationship with chip radius of curvature as a function of tool geometry, depth of cut, cutting speed, and both elastic and plastic properties of the workpiece material.     

基于DEFORM-3D的高速车削加工仿真

DEFORM-3D是应用有限元方法(FEM)分析三维复杂加工过程的模拟工具,它不仅鲁棒性好,而且易于使用.借助于该模拟分析环境,能够对切削过程中刀具几何参数、切削条件以及加工过程中的其他因素产生的影响进行研究.应用DEFORM自带的切削仿真模型,模拟高速车削加工中工件及刀具的温度分布、切屑流动、应力、应变和切削力等.模拟结果对减少产品试验、降低开发成本、缩短开发新产品及新工艺的时间等方面都具有重大意义.DEFORM-3D对于研究刀具几何模型、切屑形成以及切削参数控制的刀具制造者和使用者来说,是一个较理想的工具.     

SERRATED CHIP PREDICTION IN FINITE ELEMENT MODELING OF THE CHIP FORMATION PROCESS

A 2D Finite Element Model set up using the Arbitrary Lagrangian Eulerian (A.L.E) formulation proposed in Abaqus/Explicit (v6.4) is employed to predict serrated chip formation during cutting process. No artificial criterion is employed to create the chip or to initiate serrated chip formation. The sensitivity of serrated chip prediction to numerical and process parameters is analyzed in this paper. Experimental tests in orthogonal cutting conditions on machining of AISI-4140 with coated and uncoated cemented-carbide inserts were carried out to validate numerical results. They showed significant influence of cutting speed and rake angle on the serrated chip phenomena. The comparison between numerical and experimental results showed a good qualitative agreement and underlined the outstanding influence of the element dimensions employed in Finite Element Modeling (F.E.M.) tests.     

圆弧刃刀片的断屑性能

通过对新设计三种直径圆弧刃刀片的断屑槽型进行断屑性能的试验研究，得出了在不同切削条件下的断屑特点和有效断屑范围。