Machining Line Planner输出STEP-NC数控程序的研究

介绍了STEP-NC的概念、数据模型及其结构特点,然后通过对比MLP(Machining Line Planner)和STEP-NC数控程序对特征和操作的不同定义方法,分析了在MLP中特征及加工工艺与STEP-NC的对应关系,探讨了在MLP中实现输出STEP-NC格式的零件加工程序的方法。

PLANNING METHOD OF TOOL ORIENTATION IN FIVE-AXIS NC MACHINING

The planning method of tool orientation in the five-axis NC machining is studied. The problem of the existing method is analyzed and a new method for generating the global smoothing tool orientation is proposed by introducing the key frame idea in the animation-making. According to the feature of the part, several key tool orientations are set without interference between the tool and the part. Then, these key tool orientations are inter- polated by the spline function. By mapping the surface parameter to the spline parameter, the spline function value is obtained and taken as the tool orientation when generating the CL file. The machining result shows that the proposed method realizes the global smoothing of the tool orientation and the continuity of the rotational speed and the rotational acceleration. It also avoids the shake of the machine tool and improves the machining quality.

Research on cubic polynomial acceleration and deceleration control model for high speed NC machining

To satisfy the need of high speed NC (numerical control) machining, an acceleration and deceleration (acc/dec) control model is proposed, and the speed curve is also constructed by the cubic polynomial. The proposed control model provides continuity of acceleration, which avoids the intense vibration in high speed NC machining. Based on the discrete characteristic of the data sampling interpolation, the acc/dec control discrete mathematical model is also set up and the discrete expression of the theoretical deceleration length is obtained furthermore. Aiming at the question of hardly predetermining the deceleration point in acc/dec control before interpolation, the adaptive acc/dec control algorithm is deduced from the expressions of the theoretical deceleration length. The experimental result proves that the acc/dec control model has the characteristic of easy implementation, stable movement and low impact. The model has been applied in multi-axes high speed micro fabrication machining successfully.

Optimization of cutter-location for 5-axis NC machining freeform surface with a flat-end cutter

axis NC machining freeform surface with a flat end cutter can theoretically improve material removal rate and surface finish, but it is very difficult to generate a gouge free cutter location. A new method of generating optimal cutter path is proposed to define the effective radius of a flat end cutter and determine the optimal step forward distance and step over distance. Thereby improving the NC machining efficiency and quality of freeform surfaces.

A non-uniform allowance allocation method based on interim state stiffness of machining features for NC programming of structural parts

For thin-walled parts,uniform allowance to each machining surface is allocated by the traditional machining method.Considering the sequence of the adjacent machining features,it may cause poor stiffness for some side walls due to a minor wall thickness,which may cause the deformation of the final formed parts to be large,or deduce machining efficiency for some machining features due to too thick remains.In order to address this issue,a non-uniform allowance allocation method based on interim state stiffness of machining features for the finishing of thin-walled structural parts is proposed in this paper.In this method,the interim state model of machining features is constructed according to the machining sequence of the parts,and the stiffness of the side wall is taken as the evaluation index to allocate reasonable allowance value to the corresponding machining surface to ensure the stiffness requirement of the parts in the machining process.According to the finite element simulation results,the non-uniform allowance allocation method proposed in this paper can effectively improve the stiffness of the parts and reduce the deformation of the parts,when compared with the traditional uniform allowance machining method.

A NURBS Fitting Optimization Method for High⁃Speed Five⁃Axis NC Machining Path Based on Curvature Smoothing Preset Point Constraint

Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of the tool path.It may cause a sudden change in the drive force of the feed axis,resulting in a large fluctuation in the feed speed.This paper proposes a new non-uniform rational B-spline(NURBS)curve fitting optimization method based on curvature smoothing preset point constraints.First,the short line segments generated by the CAM software are optimally divided into different segment regions,and then the curvature of the short line segments in each region is adjusted to make it smoother.Secondly,a set of characteristic points reflecting the change of the curvature of the fitted curve is constructed as the control apex of the fitted curve,and the curve is fitted using the NURBS curve fitting optimization method based on the curvature smoothing preset point constraint.Finally,the curve fitting error and curve volatility are analyzed with an example,which verifies that the method can significantly improve the curvature smoothness of the high-curvature tool path,reduce the fitting error,and improve the feed speed.

Study on Machining Process Simulation of Machining Center and NC Optimization Technology

This paper discusses the compiling and transferring of a NC program,then,by applyingthe concept of machining scenario,presents the process of 3-dimension dynamic graphic sim-ulation based on a NC program.This technique can be used in the simulation of NC machin-ing process carried out on a multi-axis machining center.In the end of this paper,some opti-mization principles for tool pathes and machining parameters are put forward.

NC Machining of Spiral Bevel Gear and Hypoid Gear Based on Unity Transformation Model

A unity transformation model (UTM) was presented for flexible NC machining of spiral bevel gears and hypoid gears. The model can support various machining methods for Gleason spiral bevel gears and hypoid gears, including generation machining and formation machining for wheel or pinion on a universal five-axis machining center, and then directly produce NC codes for the selected machining method. Wheel machining and pinion machining under UTM were simulated in Vericut 6.0 and tested on a five-axis machining center TDNC-W2000 with NC unit TDNC-H8. The results from simulation and real-cut verify the feasibility of gear machining under UTM as well as the correctness of NC codes.

MATHEMATICAL MODEL OF NC MACHINING NONCONVENTIONAL MILLING CUTTERS-FORMING METHOD OF RAKE FACES

How to generate rake faces of nonconventional milling cutters (NCMC) with constant spiral angled and normal rake angled edges on NC machine tools is presented by use of a blunt cup grinder or a cup milling cutter. Motion functions of the NC machining system are mathematically deduced and exam- ed by a experiment. The research will provide theoretical and practical guidance for machining noncon- ventional tools on NC machine tools.

一种基于PC-NC的免编程数控系统的CAM处理方法

基于PC-NC的新型数控系统平台,既能保证数控系统必需的稳定可靠性,又能充分利用PC机的应用普及优势,是为满足快速增长的无需编程数控系统市场需求而进行的数控技术应用创新。来源于国内各行众多小微规模工厂的各类材料的零配件、磨具数控深加工需求量巨大,针对这类需求介绍一种免数控编程的CAM处理方法,在PC端直接画图或导入异形工件图形,经过识别统一抽象解析为简单的直线和圆弧,结合用户工艺设置信息封装形成链表数据结构,经过数据分类转换、刀具路径偏移处理、工艺类型处理形成G代码,再下发到数控系统NC运行,整个处理过程用户只需选图做工艺设置,无需数控编程,提升了生产加工效率,降低了数控系统使用门槛和成本。

ADAPTIVE STRATEGIES FORNC MACHINING COMPOUND FREE-FORM SURFACES

This paper treats adaptation to the machining precision and productivity of compound free-form surfaces. The principle of a mixed NC machining method (surface direct interpolating (SDI[1])and discrete NC programming) is introduced- Three adaptive procedures are discussed : ( 1 ) adaptivedivision of the machining areas, (2) adaptive triangulation for generating interference-free tool pathsfrom compound surfaces, (3) machining along surface/surface intersection (SSI ) curves with anadaptive step length. They upgrade the intelligence of machining compound surfaces.

Image Based NC Programming of Plane Contour Machining

Simplified Hough Transform (HT) and Adaptive Including Box (AIB) approach are proposed. The size of AIB is controlled according to the precision requirement of machining. The image data of part contour is turned into a set of line segments and then NC program for machining the contour is generated .

模具高速加工的NC编程策略

文章从优化高速加工工艺过程的角度出发 ,详细阐述了模具高速加工的NC编程策略 ,包括高速加工刀具轨迹生成的基本原则及方法、适应高速加工的切削用量选择、采用高速高精度的高速加工关键控制技术、典型型面及难加工型面的高速加工策略等方面 ;并针对实际加工过程 。

基于通用五坐标数控机床螺旋锥齿轮NC加工研究

基于空间曲面共轭原理 ,确定齿轮切齿矢量关系 ,建立了螺旋锥齿轮的齿面矢量方程。利用空间坐标系的变换 ,确定出刀具相对工件的位置和姿态 ,实现刀具与工件的相对运动 ,从而将传统的螺旋锥齿轮机床加工调整参数转换为适合 NC机床加工的运动参数。进行了五轴加工的刀具扫描体计算。在计算机上 ,对螺旋锥齿轮数控加工进行了仿真 ,给出了相应的计算和实验结果。在通用五坐标数控机床上实现螺旋锥齿轮加工 ,确定出螺旋锥齿轮

五轴NC加工中刀具运动包络面的计算

在机械加工过程中,刀具的铣削在加工体表面形成沟槽,对该沟槽型面的数字化描述是精确计算表面加工残差、判断加工干涉的理论基础,进而可实现表面加工精度评估与控制及加工轨迹全过程的精确规划计算。沟槽型面是刀具刃口回转面在空间运动形成的包络面的一部分,因此推导包络面的解析方程成为解决问题的关键。结合五轴加工机床的运动特点,通过建立加工刀具刃口回转面的数学模型,推导出五轴NC加工刀具运动刃口回转面包络的解析方程。数字仿真的结果与实际完全一致,验证了方法的正确性和有效性,具有较强的理论性和实用价值。

不同类型CNC五轴工具磨床的运动参数转换原理

详细分析了CNC五轴立式砂轮平动工具磨床 (P型 )和砂轮摆动工具磨床 (B型 )的运动形式及其加工原理 ,并将之与传统机床进行了比较 ;从所要求的同一个几何参数刀具具有相同的几何本质出发 ,给出了P型和B型 2种类型CNC工具磨床的内在运动参数的转换关系。研究阐明了在刀具磨削成形的过程中 ,控制每个瞬时砂轮几何体和工件几何体在空间的相对位姿和相对运动趋势是精确成形的关键。

CMM检测路径的生成及其在NC验证环境中的仿真

讨论了坐标测量机使用触发式测头进行测量时 ,检测路径的生成方法 ,定义了和检测路径生成直接相关的一些控制参数。针对目前对数控加工过程的 NC验证研究比较多 ,而且比较成熟 ,但专门针对 CMM检测过程路径仿真的软件系统并不多的现状 ,根据球头铣刀数控加工过程与 CMM检测过程在运动上的相似性 ,利用数控加工过程的 NC验证环境有效地对

STEP-NC数控技术研究进展

为全面掌握STEP-NC标准的产生、发展与研究情况,分析和总结了近10年来相关领域的研究成果。在分析和总结过程中,将相关研究分为5个主要方向,分别总结了各个研究方向的研究情况和存在的问题,归纳出未来研究中的主要科学问题和技术难点;指出STEP-NC制造系统的核心技术;提出STEP-NC制造系统架构和STEP-NC数控系统的发展趋势。

虚拟加工中NC代码转化技术研究

在虚拟加工过程中 ,虚拟机床是由刀位文件驱动而工作的 ,为了使虚拟加工环境具有接收和检验NC代码的功能 ,需要将NC代码翻译成刀位文件。该文在对NC代码翻译成刀位文件的可行性进行研究后 ,开发出了NC翻译器。翻译器共分以下几个模块 :文件的读入与存储、错误分析与语义分析、翻译执行、数据轨迹仿真等。最后并给出了槽型凸轮的NC代码的翻译实例验证 。

自由曲面NC加工无干涉刀具轨迹生成

对自由曲面ＮＣ加工中的干涉情况和现有处理方法进行分析．以曲面模型→刀具接触点数据→无干涉刀位数据为基本求解策略，综合多种优化措施。