假肢接受腔阳模数控加工刀具的运动轨迹规划

应用表面建模方法，建立了假肢接受腔的三维数学模型。针对假肢接受腔的独特外形特征，研制了加工假肢接受腔阳模的三轴联动数控机床，该机床控制系统采用开环系统，可以运行CAD／CAM软件。对加工假肢接受腔阳模的刀具进行了运动轨迹规划，推导出了切削点的计算公式。根据三维刀具半径补偿原理，确定了刀具的刀位点运动轨迹。经过临床实例加工表明：该数控机床和刀具运动轨迹规划算法完全满足实际应用要求。     

自由曲面的CNC直接插补加工技术

在ＣＮＣ系统上直接根据曲面几何定义与加工工艺参数对多轴贡面加工的连续运动轨迹进行实时插补控制，在ＣＮＣ上直接在ＡＰＴ高级语言编程，极大地科化了零件程序，并可在线修改与补偿机床运动结构、刀具形状尺寸及加工作量等工艺参数，使曲在线曲面精加工经济而高效。在单ＣＰＵ硬件环境下实现了从一般二次曲线到复杂的参数组合曲面，从两轴加工到复杂的五轴联动功能，可采用多种加工刀具与加工方式，可实时检测与处理刀具干涉，并     

A radius compensation method of barrel tool based on macro variables in five-axis flank machining of sculptured surfaces

Barrel tool radius compensation is very important to improve the five-axis CNC machining precision and efficiency of sculptured surfaces. By combining macro variables and math function of CNC controller, a radius compensation method of barrel tool based on macro variables in five-axis flank machining of sculptured surfaces was presented. The basic principle of barrel tool radius compensation in five-axis flank machining was firstly investigated. For a specific five-axis CNC machine tool with dual rotary tables, a relationship equation between compensated cutter location (CL) data and machine control (MC) data could be derived. A post-processor with the function of five-axis barrel tool radius compensation was then developed by using the C++ language, which could generate the NC programme with macro variables of barrel tool radius compensation. Finally, the NC programme was obtained automatically by the developed post-processor for the aero-engine blade surface machining. The machining process was simulated on the software VERICUT, and machining experiments were also conducted on the five-axis machine tool. Both the simulation and experimental results showed that the proposed method could perform the function of barrel tool radius compensation in the NC programme for five-axis flank machining.     

Generating collision-free tool orientations for 5-axis NC machining with a short ball-end cutter

A novel tool orientation optimisation algorithm is proposed for 5-axis NC machining with a short ball-end cutter. It can generate collision-free and smooth tool orientations along with a safe and shortest tool length (SSTL). The use of shorter cutters without collision is a key advantage of 5-axis machining because the magnitude of tool deflection and the stability of cutting process are greatly affected by the slenderness ratio of the cutter. Existing methods can calculate the SSTL in the NC simulation process. However, the SSTL is essentially determined by the tool orientations and should be considered in the process of tool path generation. To overcome this limitation, a new tool orientation optimisation algorithm is proposed. The SSTL is determined by optimising the tool orientations under the constraints of global collision avoidance and tool orientation smoothness. The algorithm first computes the global accessibility cone and the SSTL along each accessible tool orientation. Then the tool orientations are optimised based on the discrete dynamic programming with the SSTL along the whole tool path being the optimisation objective. Finally, the tool path is generated by globally smoothing the tool orientations. Computational examples and cutting experiment are given to illustrate the validity and efficiency of the proposed algorithm.     

Interference-free tool path generation for 5-axis sculptured surface machining using rational Bézier motions of a flat-end cutter

This paper presents a new approach that uses rational Bézier motions to generate 5-axis tool path for sculptured surface machining (finish cut) with a flat-end cutter. By using dual quaternion to represent a spatial displacement, the representation of kinematic motions for the cutter bottom circle of the flat-end cutter is formulated. Based on that, a new approach for tool path generation using rational Bézier cutter motions is described, in which key issues such as interference avoidance and surface accuracy requirement are addressed. First, a set of cutter contact points on an iso-parametric curve of the designed surface is obtained based on a given fitting tolerance. The associated cutter locations (CLs) are then obtained by finding the suitable cutter orientations that avoid any gouging. The conversion from the CLs to dual quaternion representation is carried out and the rational Bézier dual quaternion curve for cutter motion is generated. The entire tool path is therefore established based on the cutter undergoing the rational Bézier motion. Next, the whole tool path is checked to find (1) if there is any interference between the cutter and the designed surface, and (2) whether the deviation between the surface generated by the cutter motion and the designed surface is larger than the given tolerance. The problematic CLs, which cause either gouging or accuracy problem, are then modified. The process of tool path checking?→?CLs modification?→?tool path regeneration continues until the whole tool path is interference-free and satisfies the accuracy requirement. Furthermore, a more accurate representation of the effective cutting shape is proposed, which is used to evaluate the scallop height between adjacent tool paths. A method for constructing the adjacent tool path has been developed by considering the allowable scallop height. Finally, computer implementation and an illustrative example are presented to demonstrate the efficacy of the approach.     

高速激光切割机床数控加工态势识别系统

当前方法设计的系统对机床数控加工态势进行识别时,没有对噪声进行回放,对切割平面度、切割定位精度、机床平稳性进行识别时,识别结果不准确,存在识别准确率低的问题。该文提出高速激光切割机床数控加工态势识别系统设计方法,首先,通过运动控制卡,伺服控制模块及加工态势识别模块构成高速激光切割机床数控加工态势识别系统的架构;其次,在加工态势识别模块中设计系统初始化、态势识别、自动诊断报警、运动控制、图形转码和G代码编译等子模块,在此基础上,通过噪音采集、噪音回放和信号分析等方法提高加工态势识别的准确率;最后,采用HMM算法构建高速激光切割机床数控加工态势识别模型,实现加工态势识别。实验结果表明,加工态势设计方法设计的系统可有效识别机床的切割平面度、切割定位精度和机床平稳性,识别准确率较高。     

A tool path patching strategy around singular point in 5-axis ball-end milling

In 5-axis high-speed milling, large incoherent movements of rotary axes around the singular point are known to be a problem. Correction methods found in the literature deal mostly with the collision that may happen between the tool and the part but not with the feedrate slowdowns which affect surface quality and machining productivity. The method proposed in this paper addresses both geometrical and productivity issues by modifying the tool axes orientation while respecting maximum velocity, acceleration and jerk of the machine tool axes. The aim is to detect these behaviours and replace the considered portion of the tool path by a patch curve respecting kinematical constraints of the machine tool. Compared to previous works, the inserted patch curve is not constrained to pass through the singularity but respect tangential constraints to ensure the monotony of the tool path and is also connected with the rest of the tool path to ensure a continuity up to the third derivative in order to fulfil jerk limitations. For that purpose, the initial articular positions of the rotary axes around the singular point are fitted with B-spline curves, modified and finally discretised for linear interpolation. Experimental investigations on a test part are carried out to show the efficiency of the method in terms of feedrate and surface quality.     

数控刀具材料的研究进展

数控刀具是数控加工技术中的重要基础装备之一,在保证制造技术的有效实施方面有着十分重要的作用。本文主要介绍数控机床刀具的分类、数控刀具材料的现状和发展趋势。     

基于曲率的曲面加工刀位轨迹生成算法

提出了一种自由曲面五轴数控加工无干涉刀位轨迹的生成算法。该方法利用曲面的曲率来确定环形刀的刀具姿态,使得刀具随被加工曲面的形状变化而倾斜,从而生成无干涉的刀位轨迹。     

The Research of CNC Machining Cutter Choice Based on CAXA

The article introduces the unique characteristics of CNC machining center cutter compared to traditional cutters,analyzes the choice of CNC machining cutter and factors of choice.Meanwhile,proved by the examples with manufacture software CAXA2004,the correct choice of CNC machining center cutter can give full play to the advantages of CNC machining and improve the economic efficiency and production levels of enterprises.     

Adaptive nonlinear tool path optimization for five-axis machining

Current tool path computation in the CAM algorithms approximates the surface by piecewise linear interpolation. In the case of three-axis machining on a CNC machine the tool will exactly reproduce this computed tool path. However in the case of five-axis simultaneous machining the real tool path on the CNC machine will not follow the linear approximation computed by the conventional CAM algorithm. A new CAM algorithm is proposed which approximates the surface to be machined by a piecewise curved approximation. This curve represents the real tool path followed on the five-axis machine. This piecewise curved approximation is further optimized by formulating the tool path computation as the generation of a grid based on a variational smoothness penalty function. This new algorithm considerably improves the accuracy and reduces the number of blocks and machining time.     

一种基于STL模型的5轴高速加工刀轨优化策略

针对线性插补刀轨不连续且插补点多的缺点,提出了一种基于STL模型的口腔修复体5轴高速铣削数控加工刀轨优化策略。以去除不必要的插补点,简化加工刀轨的数量,优化刀轴矢量包络的曲面为平滑变化的规则面,实现了一种支持HEIDENHAIN数控系统的样条插补新方法。运用该策略线性插补的G代码成功地被转换成样条代码,基于Vericut仿真器,仿真加工出了磨牙冠修复体。结果表明,该优化策略不仅能缩短切削时间、提高加工质量,而且可避免切削颤振。     

拉刀重磨数控加工系统的研究

提出了拉刀数控重磨及拉刀刃形自动测量的原理与方法，并应用这些原理与方法开发了拉刀重磨数控加工系统。所开发的系统已经成功应用于机床厂合作开发的数控拉刀磨床产品中。该产品填补了国内空白。     

Integrated method for tool path generation in five-axis sculptured surface machining

Five-axis machining allows continuous adjustment of cutter orientation along a tool pass. Unfortunately, the flexibility has not been fully exploited due to the separate consideration of tool path generation and cutter orientation in current machining methods. This paper presents an integrated method (IM) for tool path generation, which is tightly integrated with the orientation strategy, to minimise tool path length under the constraint of smooth cutter orientation. Distinctively, cutter orientation along a tool pass is optimised by balancing considerations of maximum material removal and smoothness of cutter movement. Further, the intervals between successive tool passes are maximised according to the optimised orientation. In the paper, the IM is combined with the quadric method, a recently developed cutter orientation strategy, for iso-parametric machining with a flat-end cutter. However, the method could be applied to other orientation strategies with different machining mechanisms and cutter types. Simulated examples illustrate that the IM is more efficient in machining than established methods.     

Optimal cutter size determination for 2½-axis finish machining of NURBS profile parts

A curve model of non-uniform rational B-spline (NURBS) has been widely adopted in mainstream CAD/CAM software systems to design complicated geometries of mechanical parts, for example, the curved profiles of pockets, sides, and islands. NURBS profile parts (the profiles include NURBS curves for pockets and islands) are produced in 2½-axis rough and finish machining. In rough machining of the parts, several end-mills with different sizes are employed for high cutting efficiency, and in finish machining, a single end-mill is usually used to cut along the profiles for high surface quality. To accurately produce the geometries with NURBS curves in finish machining, the cutter size should be optimised in order to eliminate gouging and save machining time. Although this topic has been a research focus for a decade, optimal cutter size determination still remains as a technical challenge. To rise to this challenge, our work proposes a new approach to determining the largest allowable size for the cutter to move along all the profiles (including NURBS curves) in 2½-axis finish machining without global and local gouging. The salient feature of this approach is that an original model of the cutter size is formulated and an effective solver–the particle swarm optimisation method–is employed to compute the largest allowable cutter size. This intelligent approach is more efficient and accurate than the conventional computational method based on the test examples in this work. It can also be applied to global and local gouging detection for NURBS profile machining. Our research work has great potential to advance CNC machining techniques.     

Three-dimensional profile curve machining on three-axis machines

Presented in this paper is a tool path generation procedure for three-dimensional profile curve machining on three-axis machines, which is essential for making dies of automotive press panels. While sculptured surface machining has received a significant amount of attention, there has been very little work on profile curve machining. The most distinctive feature of profile curve machining is that the machine operator determines the exact cutter radius at the stage of numerical control (NC) machining. For this reason, profile curve machining usually makes use of the cutter radius compensation functionality of an NC controller. In this paper, four technological requirements for the profile curve machining are identified: (1) maintaining a constant machining width; (2) avoiding controller alarms; (3) avoiding unbalanced cutter wear; and (4) retaining down-milling. To satisfy these requirements, a tool path generation procedure is proposed, implemented and tested.     

UG集成环境下数控机床虚拟样机的实现

数控机床是一种重要的技术装备。为提高数控机床的设计水平和能力,在数控机床的设计开发过程中需要引入新的技术和设计手段。为把虚拟样机技术应用到数控机床设计开发的工程实践中,基于虚拟样机的概念讨论了数控机床虚拟样机的具体实现过程,分析比较了实现该过程的分布式软件平台和UG集成软件平台的特点。以数控铣床新产品开发为例,研究了UG集成环境下数控机床虚拟样机的构建与仿真过程,包括数字模型与装配、运动仿真、结构分析以及在虚拟样机上的加工仿真,给出了相应的示例。研究表明,应用UG的各功能模块可以有效地构建数控机床的虚拟样机并对其进行全面的仿真,使所设计的数控机床得到全面优化,为数控机床的开发设计提供了一种可行的先进方法。     

数控机床校准周期的合理确定

从具体实际出发,充分分析影响机床最终加工精度的诸多因素,应用田口方法科学合理地确定数控机床的最佳校准周期,保障机床加工过程的质量控制.     

A review of numerically controlled methods for finish-sculptured-surface machining

This paper presents a mathematical review of methods and algorithms used to compute milling cutter placement for multi-axis finished-surface machining. In general, these methods and algorithms compute tool path points based on tangent-plane contact between the milling cutter and the surface while maintaining a fixed tool orientation. This tangent-plane method of tool positioning and orientation is examined by discussing its strengths and weaknesses. Errors resulting from the tangent-plane approach are typically determined using a posteriori cutter path checking and graphic visualization techniques. Although these checking techniques have proved useful in identifying the tool path errors before actual machining, the problem of generating an error-free tool path remains. In this paper, we discuss the analysis of tool path position and orientation data as they are generated. This a priori analysis method is used to show error locations along the lateral face of the tool. The conclusion is reached that additional research is needed in the area of simultaneous multi-axis tool path planning, if errors are to be eliminated and the efficiency of the milling machine is to be improved. The reader is referred to research efforts that extend beyond the traditional or computer-aided design (CAD, vendor supplied) tool path planning methods. Some of these efforts show great promise in eliminating gouging and improves machine tool efficiency.     

基于Storm流处理的数控机床运行数据监测方法的设计与实现

针对目前数控机床运行数据种类多、数量大且难以实现实时处理的问题，提出一种基于Storm流处理技术的数控机床运行数据监测方法。该方法采用实时大数据计算框架Storm作为核心，通过外置传感器和数控系统通信协议获取数控机床运行数据。使用Kafka作为消息队列将机床运行数据上传给Storm，然后在Storm框架中进行数据统计、数据异常检测等实时分析业务，之后将分析结果存储于数据库中，并实现分析结果的可视化展示。在实际生产环境中对基于Storm流处理的监测方法进行测试，实验结果表明：该方法能够实现对数控机床运行数据的实时监测与处理，具有强实时计算能力、高扩展性的优点;并且在处理相对复杂的数控机床运行数据监测业务时，该方法的优势更显著。研究结果为数控机床运行数据监测提供了新思路，该监测方法具有广阔的工程应用前景。