基于特征的数控加工刀具路径参数化设计

为了实现刀具路径高效的设计,对一种基于特征的数控加工刀具路径参数化设计方法进行了研究。首先对特征进行分类和参数化描述,然后为每一类特征设计其刀具轨迹通用模型,实际应用时,通过具体的特征参数生成对应的刀具轨迹。文中以槽特征为例,说明了参数化设计的思路和方法,采用Visual C++及OpenGL编程语言,实现了其参数化设计,并通过仿真验证了方法的正确性。     

基于WEB的刀具参数化图形系统设计与实现

应用面向对象技术的项目管理方案,结合刀具的参数化设计的基本思想,重点阐述了系统数据库设计、基本模块设计,并给出刀具参数化设计过程的一个简单应用实例,开发了基于WEB的刀具参数化图形系统,实现DWG图形文件的在线生成和显示,同时,提高了设计人员设计效率.     

复杂螺旋曲面铣削加工刀具的廓形设计

针对螺杆压缩机第三代型线的特点,研究用于螺旋曲面加工的铣削刀具的廓形设计.文章依据刀具回转面与螺旋曲面的包络原理,以用于螺旋曲面加工的铣削加工刀具--盘形铣刀的设计为研究对象,采用微分几何曲线曲面的构建方式,首先建立了螺旋曲面的特性方程,然后根据刀具与工件的接触条件建立接触线方程;提出了加工螺旋面用盘形刀具廓形设计的基本理论和方法,并通过实例验证了盘形刀具设计的理论计算公式.结果表明,铣削加工螺旋曲面的盘形刀具截形设计的关键是建立接触线方程,借助Matlab软件进行数值运算而求出刀具廓形的坐标是精确的,且能够满足产品设计要求.     

包络法数控加工螺杆的刀具轨迹计算方法

针对目前包络法数控加工螺杆的数控编程序系统采用平面包络计算方法存在理论误差这一现状,提出从空间啮合原理出发生成刀具运动轨迹的新方法。在建立刀具和工件模型找 ,推出计算刀位点的方程,从而得到刀具运动轨迹的计算式。只要给定工件端截面参数方程,就可采用该方法生成刀具运动轨迹。该方法适用于各种截面廓形为一阶连续可微曲线的定螺距圆柱面螺杆。对于截面廓形由多段曲线组合成的螺杆,可以分段处理。     

圆体成形车刀廓形的计算机辅助设计

本文通过建立圆体成形车刀廓形设计的数学模型，利用计算机编制出了求解刀具廓形上各半径数值表的源程序及其相应表格，比起传的设计方法有很大的改进，对工厂设计人员有重要参考价值。     

面向绿色产品制造技术的新型数控刀具材料研究分析

随着环境问题的日益严重,要求制造技术的发展必须与自然资源和环境相结合,推行绿色制造技术给机械工业带来了新的发展机遇;本文探讨面向绿色产品制造技术的新型数控刀具材料发展方向,进一步分析数控刀具材料的合理选用;为数控刀具参数化设计提供理论依据.     

基于Matlab的双螺杆泵螺杆成型铣刀廓形求解

根据双螺杆泵螺杆转子端面型线方程,建立基本的铣刀刀刃廓形方程,利用Matlab软件对设计刀具过程中的三角超越方程等非线性方程进行求解,得到一系列有效的廓形离散点数据。对于铣刀廓形求解过程中,因工件廓形尖点的存在而导致铣刀廓形出现刃形分离现象进行研究,以准确求解铣刀刃形。     

高精度棱体成形车刀的CAD/CAM系统

研究了高精度棱体成形车刀优化设计的数学模型,介绍了用VB语言开发的高精度棱体成形车刀的CAD/CAM子系统的构成及其主要模块的功能.该系统可由工件零件图直接生成加工该工件的高精度圆体成形车刀的零件图及刀具廓形的数控线切割加工程序,同时还能通过仿真检验所设计的刀具廓形及其加工程序代码的正确性.     

双螺杆泵螺杆成型铣刀廓形设计与研究

根据螺杆螺旋曲面方程,利用成形铣削原理和坐标变换理论,从成形铣刀与螺杆工件的相对运动关系出发,建立了基本的铣刀刀刃廓形方程。应用Matlab对接触方程进行快速准确的求解,得到一系列有效的廓形离散点数据,再利用Pro—E准确地绘制出刀具的三维模型图。该方法能方便、快捷、准确的完成螺杆型面铣削刀具设计。     

复杂螺旋曲面加工刀具参数的优化设计

在螺旋曲面铣削加工过程中,刀具参数对所形成的螺旋面精度有很大的影响,为了满足其精度的需要,文章针对双螺杆混输泵转子截面廓形的几何特点,依据空间圆弧逼近原理,对转子螺旋曲面的加工刀具进行了参数优化设计,并通过计算实例验证了该优化方法的可行性。     

基于有限元法的镗孔专用机床床身分析

机床床身是机床的核心部件,对提高机床本身机加工精度有着非常重大的意义与影响力。以泵车水箱加工的镗孔专用机床为研究对象,利用Solidworks软件进行床身及相关零件的三维造型,再把实体模型导入ANSYS Workbench中进行静力学和动力学分析。通过不同筋板形式床身的比较,确定合适的筋板布局形式,进而对选定筋板形式的床身结构进行优化分析,最终确定床身的结构。     

Experimental investigation and simulation of machining thin-walled workpieces

An enhanced simulation model is presented in this paper to predict form deviations in end milling processes of thin-walled structures. The calculation of tool engagement is based on level curves representing surface geometry of the workpiece and the NC code driven sweep volume. To consider influences of force-induced deflections resulting in static form errors on machined surface of the workpiece, a model for superposed stresses is enclosed. Derived from the tool engagement, the cutting force is predicted using a parametric force model. The experimental investigations within the measuring of static and dynamic form errors during processing and afterwards are shown and measurement results are compared with results of the cutting simulation to verify the proposed method. The presented achievements are deduced from research activities aiming at an increased understanding of shape deviation induced by interactions between tool, workpiece and clamping device during machining.     

The form error prediction in side wall machining considering tool deflection

In this research, an effective method for the form error prediction in side wall machining with a flat end mill is suggested. The form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. The developed model can predict the surface form error accurately about 300 times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.     

CAD orientated mathematical model for determination of profile helical surfaces

A mathematical model is developed for the determination of the profile of the helical surface when the profile of the initial tool surface profile and the parameters determining the tool orientation towards the blank are specified. It also encompasses the cases when the tool is inclined towards the vertical line. The specification of the tool surface profile is discrete (by coordinates). There are no limits for the application of this method and the complexity and variety of the form of the specified tool profile. The developed mathematical model for solving the reverse task is CAD orientated and may be used as a basic part of a specialized CAD system.     

Development of an analytical scheme to predict the need for tool regrinding in shearing processes

This paper describes an analytical scheme for the prediction of the tool wear and the need for tool regrinding in the sheet metal shearing process. The finite element program developed is used for the analysis of the shearing process in this study. In order to predict tool wear, Archard's wear model is reformulated in an incremental form and then the wear depth on the tool is calculated at each step in the deformation using the result of finite element analysis, taking consideration of the sliding velocity and normal pressure over the contact area. In general, the need for regrinding of the shearing tool is determined on the basis of allowable burr height on the final product. Therefore, based on this criterion, the analysis of the shearing process is iteratively performed using the worn profile on the tool in order to predict the need for tool regrinding. To analyze the quantitative wear of the tool, the parameters included in the wear model are determined by the result using a wear test, such as a pin-on-disk wear test for the material of the shearing tool and sheet metal. The effectiveness of the proposed scheme is verified by comparison with experimental results. It is shown that the simulation results are in good agreement with those obtained experimentally and the need for regrinding of the shearing tool can be determined for an allowable burr height.     

An analysis of the volumetric error uncertainty of a three-axis machine tool by beta distribution

This paper addresses the stochastic nature of the volumetric error of a machine tool in 3-dimensional workspace, and proposes a new model helping the prediction of the tolerances of products caused by uncertainties of a machine tool without going through very costly and time-consuming production evaluation. The probability of the volumetric error within the prescribed tolerance in the case of a vertical type 3-axis machine tool is obtained in 3-dimensional graphical form and the beta distribution is adopted to obtain a distribution that can better approximate the real distribution of the sum of the variables. The direction of approach of a tool/workpiece is considered when the stochastic error parts of a machine tool are evaluated. In addition, we verified experimentally that the stochastic parts of the volumetric error are also affected by the direction of approach of a tool/workpiece.     

Macroscopic simulation of the liner honing process

The form quality, the roughness and the surface appearance produced by honing minimizes the friction of the piston in the liner. The process is however mechanically complex and the selection of the process parameters is currently based on empirical methods. The aim of this paper is thus to develop a macroscopic simulation environment of complete real honing cycles, which will help end-users during the setting-up. This virtual tool is based on a space–time discretization and a macroscopic cutting model taking into account local contacts between the workpiece and the abrasive tool. The space–time discretization allows representing the machine environment with the tool, the workpiece and the kinematics. Simulation results are finally validated by comparison with industrial experiments.     

Simulation of milling tool vibration trajectories along changing engagement conditions

This paper presents a simulation system, which is able to model engagement conditions as a syntactical geometric model along arbitrary NC-programs. This modeling approach allows the feedback of tool deflections into the model of the chip form, which enables the simulation of regenerative tool vibrations along changing engagement conditions. Methods from the field of computer graphics allow a fast analysis of the chip forms as well as a fast cutting force calculation, which is essential to speed up this time-domain simulation system. Experiments show a good agreement of calculated and measured tool trajectories even along sudden changes of the radial immersion. Furthermore, a geometric model of the workpiece is applied, which is able to represent the surface structure resulting from a vibrating cutting tool. Thereby, chatter marks as well as the effects that occur along changing engagement conditions can be modelled and rendered realistically.     

搅拌摩擦焊接偏心挤压流动模型

提出了一种偏心挤压流动模型,该模型认为搅拌头对软化材料的偏心挤压作用是形成接头的主要因素.基于该模型,设计并进行了偏心搅拌摩擦焊接试验.结果表明,搅拌摩擦焊接过程中,接头是由搅拌头偏心挤压材料形成的;搅拌头的偏心量越大,形成的接头核心区也将越大;在搅拌针附近的金属流动将使焊接接头形成在行进方向的层状结构;在接头表面将形成弧形纹,形成的弧形纹不是沿板材对接面对称的,而是偏向后退侧的,弧纹在后退侧形成的弧纹夹角比前进侧形成的弧纹夹角大;行进方向的层状结构和接头表面的弧形纹有对应关系.     

New observations on tool wear mechanism in dry machining Inconel718

Tool wear is a problem in machining nickel-based alloy Inconel718, and it is thus of great importance to understand tool wear. Tool wear mechanism in dry machining Inconel718 with coated cemented carbide tools was analyzed in this paper. CCD and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS) were used to study tool wear mechanism. The results show that the main reason which causes cutting tool wear was that the tool materials fall off from the tool substrate in the form of wear debris. In addition,, element diffusion between tool and workpiece and oxidation reaction all accelerate the formation and the peeling of the wear debris. According to analysis of tool wear mechanism, tool flank wear model was established. The optimal temperature in machining Inconel718 with PVD-coated (TiAlN) tool was obtained through the established model. Excellent experimental agreement was achieved in optimal temperature calculated by the established model.