A Generic Kinematic Model for Three Main Types of Five-axis Machine Tools

Material removal is one of the most used processes in manufacturing. Five-axis CNC machines are believed to be the best tools in sculptured surface machining. In this study, a generic and unified kinematic model was developed as a viable alternative to the particular solutions that are only applicable to individual machine configurations. This versatile model is then used to verify the feasibility of the two rotational joints within the kinematic chain of three main types of a five-axis machine-tool. This versatile model is very useful applied to the design of five-axis machine tools.

基于激光跟踪仪的数控机床加工误差控制研究

数控机床使用时间延长,会使加工轨迹与实际轨迹轮廓之间偏离出现加工误差,同时存在加工效率差等缺陷,为了获得理想的数控机床加工效果,提出了基于激光跟踪仪的数控机床加工误差控制方法。首先采用激光跟踪仪确定数控机床加工轨迹,引入叉耦合控制器,计算数控机床加工过程中轨迹误差估计值,然后根据误差分配结果确定加工轨迹轮廓误差补偿控制量,并根据插补值进行数控机床加工控制,最后进行仿真测试,结果表明,本方法降低了数控机床加工误差,提升了数控机床加工精度,具有较高的实际应用价值。

CNC-2150立式龙门加工中心第四轴的改造

为了解决三轴CNC-2150立式龙门加工中心实现四轴联动的问题,将在机床上增加第四轴的改造技术应用到数控机床功能扩展中。开展了系统配置的分析,建立了A轴电气控制与PMC控制程序之间的关系,提出了A轴PMC控制程序嵌入原系统程序的方法。进行了A轴精度检验和产品加工的试验。试验结果表明:A轴的精度达到了行业标准,产品质量合格,机床实现了四轴联动。通过设置、调试A轴参数和控制程序,使A轴稳定可靠运行并可以和原机床一起四轴联动。

基于VERICUT的5轴数控铣床虚拟仿真系统设计

5轴联动切削运动要比普通3轴数控铣床复杂,它释放了刀具相对工件的转动自由度,且更容易遇到刀具干涉问题的。为减少零部件试切,检验数控工艺合理性,因此,复杂零件5轴联动铣削加工前,有必要对其加工过程进行虚拟仿真。为此,本项目首先对5轴数控转动自由度原理进行了详细分析,并基于VERICUT设计一台虚拟仿真5轴数控铣床。然后以一个典型空间曲面零件作为虚拟仿真加工任务,来验证5轴联动数控加工工艺的合理性和正确性。

数控5轴联动技术在复杂曲面加工中的应用研究

随着现代制造业对于复杂曲面零件需求量的不断增加,数控5轴联动技术以其提高加工精度、缩短加工周期和扩大加工范围的特点,它已经成为复杂曲面进行高效,高精度处理的关键技术。对数控5轴联动技术加工复杂曲面的价值、关键技术、具体应用策略进行深入探究,通过对5轴联动数控系统结构进行优化设计,对加工轨迹进行准确规划及优化,并对误差进行有效建模及补偿,使数控5轴联动技术在复杂曲面加工质量及效率方面得到显著提高,为创新发展现代制造业提供强大技术支撑。

An Open CAM System for Dentistry on the Basis of China-made 5-axis Simultaneous Contouring CNC Machine Tool and Industrial CAM Software

China-made 5-axis simultaneous contouring CNC machine tool and domestically developed industrial computer-aided manufacture （CAM） technology were used for full crown fabrication and measurement of crown accuracy, with an attempt to establish an open CAM system for dental processing and to promote the introduction of domestic dental computer-aided design （CAD）/CAM system. Commercially available scanning equipment was used to make a basic digital tooth model after preparation of crown, and CAD software that comes with the scanning device was employed to design the crown by using domestic industrial CAM software to process the crown data in order to generate a solid model for machining purpose, and then China-made 5-axis simultaneous contouring CNC machine tool was used to complete machining of the whole crown and the internal accuracy of the crown internal was measured by using 3D-MicroCT. The results showed that China-made 5-axis simultaneous contouring CNC machine tool in combination with domestic industrial CAM technology can be used for crown making and the crown was well positioned in die. The internal accuracy was successfully measured by using 3D-MicroCT. It is concluded that an open CAM system for den-tistry on the basis of China-made 5-axis simultaneous contouring CNC machine tool and domestic industrial CAM software has been established, and development of the system will promote the introduction of domestically-produced dental CAD/CAM system.

数控连杆机构式机器人的平衡特性及优化

为了提升数控连杆机构式机器人的平衡特性,以一种数控连杆机构式机器人机构为研究对象,首先计算总质心坐标,采用倾覆力矩和惯性力作为机器人静态及动态平衡性评价指标;其次构建去除支链的传统机器人,将该机器人与数控连杆式机器人进行对比,对比结果表明,数控连杆机构式机器人的平均倾覆力矩比传统串联机器人减小了96.31%;在负载为10 kg的情况下,x方向和y方向的惯性力比传统机器人分别减少了20.76%、34.88%;为进一步提升机器人平衡性,以支链杆长为设计变量,总惯性力最小为目标函数,支链杆长之和为约束条件,运用遗传算法,求出其杆长最优解。优化结果表明,优化后的机器人总惯性力相比优化前减小21.67%,从而验证了杆件优化的有效性。

数控多轴联动加工赛项技术解析

全国数控铣技能大赛旨在提高数控加工技术水平和促进行业发展,复杂部件“数控多轴联动加工”为其典型赛项。对于该赛项技术解析,利于参赛选手的技术训练和准备。基于多次指导学生参加全国职业院校技能大赛高职组复杂部件“数控多轴联动加工”赛项的经验,通过对数控技能大赛技术问题深入解析,分析加工特点和难点,总结训练经验和参赛技巧,提出针对性技术措施,为选手提供实用建议,并为类似数控实际加工操作提供借鉴。

数控机床多轴联动铣削加工轨迹快速跟踪研究

数控机床多轴联动铣削加工运动学参数变化较大,导致加工轨迹跟踪误差与用时增加。提出新的数控机床多轴联动铣削加工轨迹快速跟踪方法。构建数控机床多轴联动铣削刀具和加工工件瞬时坐标系,实现二者之间的转换,根据坐标系转换结果建立数控机床多轴联动铣削加工运动学模型,结合运动学模型和强跟踪卡尔曼滤波轨迹跟踪方法实现铣削加工过程中运动轨迹的快速跟踪。实验结果表明:该方法可实现铣削刀刃上任意目标点的轨迹跟踪,轨迹跟踪误差低于0.1μm,跟踪平均用时低于1.2 ms,可快速实现高精度的铣削加工轨迹跟踪,为提升铣削加工质量提供保障。

基于PID控制的多轴联动数控机床运动误差补偿

为了降低多轴数控机床在运动过程中产生的误差,提高数控机床的控制精度,提出多轴联动的数控机床运动误差补偿方法。构建多轴联动数控机床在工作状态下的运动轨迹方程,在机床运动轨迹方程的基础上计算多轴联动数控机床的运动误差。采用粒子群优化算法优化PID控制器中的关键参数,将上述计算得到的运动误差输入优化后的PID控制器中,完成多轴联动数控机床运动误差的补偿。实验结果表明,所提方法可高精度地完成椭圆控制和螺旋旋转体控制,且运动误差补偿结果不受多轴联动数控机床运动速度的影响,具有良好的适应性。

Design and implementation of five-axis transformation function in CNC system

To implement five-axis functions in CNC system, based on domestic system Lan Tian series, an improved design method for the system software structure is proposed in this paper. The numerical control kernel of CNC system is divided into the task layer and the motion layer. A five-axis transformation unit is integrated into the motion layer. After classifying five-axis machines into different types and analyzing their geometry information, the five-axis kinematic library is designed according to the abstract factory pattern. Furthermore, by taking CA spindle- tilting machine as an example, the forward and the inverse kinematic transformations are deduced. Based on the new software architecture and the five-axis kinematic library, algorithms of RTCP （rotation tool center point control） and 3D radius compensation for end-milling are designed and realized. The milling results show that, with five-axis functions based on such software struc- ture, the instructions with respect to the cutter＇s position and orientation can be directly carried out in the CNC system.

A TOOL PATH CORRECTION AND COMPRESSION ALGORITHM FOR FIVE-AXIS CNC MACHINING

A novel approach is proposed for correcting command points and compressing discrete axis commands into a C2 continuous curve.The relationship between values of rotation angles and tool posture errors is firstly analyzed.A segmentation method based on values of rotation angles and lengths of adjacent points is then used to subdivide these command points into accuracy regions and smoothness regions.Since tool center points generated by CAD/CAM system are usually lying in the space that is apart from the desired curve within a tolerance distance,and the corresponding tool orientation vector may change a lot while the trajectory length of the tool center point is quite small,directly machining with such points will lead to problems of coarse working shape and long machining time.A correction method for command points is implemented so that good processing effectiveness can be achieved.Also,the quintic spline is used for compressing discrete command points into a C2 continuous smooth curve.The machining experiment is finally conducted to demonstrate the effectiveness of the proposed algorithm.

TOOL ORIENTATION PLANNING FOR FIVE-AXIS CNC MACHINING OF OPEN FREE-FORM SURFACES

For the geometry characteristics of open free-form surfaces,it is hard to consider global interference during the planning of feasible domains.Therefore,the optimal kinematic orientation of tool axis will no longer be confined to the boundary of feasible domains.In this paper,according to the principle demanding that the tool should be fitted to a surface as close as possible and relevant processing parameters,a feasible domain of tool orientation for each cutter contact is planned in the local feed coordinates system.Then,these feasible domains of the tool orientation are transformed into the same coordinates system of the machine tool by the inverse kinematics transformation.The linear equations based feasible domain method and Rosen gradient projection algorithm are used to improve the optimization process in precision and efficiency of the algorithm.It constructs the variation of tool orientation optimization model and ensures the smoothness of tool orientation globally.Simulation and analysis of examples show that the proposed method has good kinematics performance and greatly improves the efficiency.

基于模糊反馈的六轴五联动数控加工进给速度控制方法

为解决在数控机床实际加工中存在进给速度与设定速度不一致的一系列问题,现提出基于模糊反馈的六轴五联动数控加工进给速度控制方法。首先,基于模糊反馈控制机床旋转角度,解决机床加工的盲区问题;其次控制转动轴速度,对数控加工过程进行规划;最后,控制机床旋转位置,得到进给速度的完整控制方法。通过实验分析对此方法进行验证,实验结果表明:此基于模糊反馈的六轴五联动数控加工进给速度控制方法在零件加工时间要优于传统方法与恒定值法,加工控制所用的时间少于传统方法5.16min,少于恒定值法2.43min。

五轴联动数控机床的后置处理方法

后置处理是数控编程的重要环节 ,它的作用是将 CAM系统生成的刀轨文件转化为机床的加工代码。五轴联动的后置处理涉及到刀位文件的转角计算和坐标变换计算 ,坐标转换关系比较复杂 ,本文研究了立卧两种状态的五轴联动数控机床的后置处理 ,在分析了机床坐标系和工件坐标系关系的基础上 ,推导了坐标变换公式 ,并开发出了相应的后置处理软件 。

5轴数控机床坐标系统的一个特例及其后置处理方法

介绍了一个包含倾斜转动轴的 5轴数控机床坐标系统及其在该转动轴与主轴成 4 5°角情况下的运动特点。通过对该系统中机床运动坐标系与工件坐标系关系的分析 ,给出了 5轴联动时刀轨数据的后置处理方法 ,包括工作台转角的计算和主轴运动坐标计算。

一种新型五轴联动数控系统的研究

在目前的五轴数控加工中,编程人员需针对不同类型的五轴数控机床编制不同的加工程序.针对这一问题,本文研究并设计一种新型五轴联动数控系统.详细描述了该五轴联动数控系统的结构,对其中的RTCP模块和基于四元数的空间运动学变换模块进行了重点探讨,并对该数控系统进行了测试.实验结果表明该数控系统具备一个工作程序在不同结构的机床进行加工的功能.

五轴联动并联机床数控系统研究

分析并联机床数控系统特点,研究并联机床数控系统涉及的几项关键技术。在此基础上,以Delta Tau公司的PMAC运动控制卡为核心部件,基于工业控制计算机构建五轴联动并联机床的数控系统,然后在W indows平台上开发了该数控系统的数控软件系统,并对系统的软、硬件结构及其实现进行详细的介绍。

螺旋锥齿轮机床五轴联动数学模型创成算法

研究螺旋锥齿轮机床五轴联动数学模型创成新算法;通过空间运动等效转换,得到准双曲面齿轮加工由机械型机床向五轴联动机床转换的解析解公式;用麦克劳林级数拟合机床各轴的非线性运动方程,推导出螺旋锥齿轮制造最复杂的工艺方法即HFT(Hypoid format tilt)加工方法下螺旋锥齿轮机床五轴联动数学模型。由五轴联动运动方程在机床坐标系下虚拟制造准双曲面齿轮齿面与GLEASON公司的理论齿面进行比较,通过对比验证五轴联动数学模型的准确性与精度。研究结果表明:本文提出的螺旋锥齿轮机床五轴联动数学模型创成新算法原理正确,转换精度高。

六轴五联动数控加工非线性误差的分析与控制

多轴联动数控加工中数控系统线性插补和实际刀具轨迹的不一致性,导致了非线性误差的产生。通过建立非线性误差模型,预测了最大非线性误差的位置;通过分析曲线拟合度并采用抛物线函数法进一步完善误差模型,分析非线性误差的影响因素;通过自适应线性化法将超差程序段控制在误差允值范围内。以圆盘刀六轴五联动数控加工叶片曲面为例,对其刀位文件进行仿真分析,控制后采样程序段的非线性误差得到明显改善,最大非线性误差的标准差降低近84.5%,验证了该控制方法的有效性。