数控车削加工中刀尖圆弧半径补偿有关问题

如果数控系统不具备刀具半径自动补偿功能,则只能按刀心轨迹进行编程,但当刀具磨损、重磨或换新刀而使刀具直径变化时,必须重新计算刀心轨迹,并修改程序;当数控系统具备刀具半径补偿功能时,数控程序只需按工件轮廓编写,加工时数控系统会自动计算刀心轨迹,使刀具偏离工件轮廓一个半径值,即进行刀具半径补偿.本文讲述的是车刀刀尖半径补偿问题,文章从刀尖半径的影响进行分析,根据不同功能的数控系统进行刀尖半径补偿方法等进行讨论,有较强的实用性.     

矢量法刀具半径补偿研究

传统刀具补偿方法的计算过程复杂繁琐,计算量相对较大.提出一种新的矢量法刀具半径补偿,通过分析加工线段转接点处切线矢量夹角在平面坐标系中的分布情况,判断出不同的转接类型,并在此基础上进行刀具半径补偿计算,得出各个转接点坐标.仿真实验结果表明,该方法简单实用,较传统方法计算量显著减少,尤其是对转接点的计算,矢量法的引入使得该方法较三角函数方法具有更大的优势.     

计算机数控的半径补偿

刀具半径补偿的主要目的是将轮廓轨迹转化为刀具中心轨迹。在计算机数控中常用的刀具半径补偿是采用直线过渡方式。本文主要叙述了四种不同情况时的补偿算法,即直线-直线,直线-圆弧,圆弧一直线,圆弧-圆弧。最后述及了刀具半径补偿程序编制中的一些问题。例如比例因子的引入,运算精度的提高及实时性。     

数控铣削加工中刀具半径补偿的有关问题

在数控铣床上进行工件轮廓的数控铣削加工时,由于存在刀具半径,使得刀具中心轨迹与工件轮廓(即编程轨迹)不重合.如果数控系统不具备刀具半径自动补偿功能,则只能按刀心轨迹,即在编程时给出刀具的中心轨迹,如图1所示的点划线轨迹进行编程.其计算相当复杂,尤其是当刀具磨损、重磨或换新刀而使刀具直径变化时,必须重新计算刀心轨迹,并修改程序.这样既复杂繁锁,又不易保证加工精度.当数控系统具备刀具半径补偿功能时,数控程序只需按工件轮廓编写,加工时数控系统会自动计算刀心轨迹,使刀具偏离工件轮廓一个半径值,即进行刀具半径补偿.     

刀具半径补偿在CNC编程中能错误及正确应用

在CNC编程中,合理地引入刀具半径补偿,可以使刀具轮廓轨迹的处理变得更简单。但是,由于使用刀具半径补偿要遵循很多相应法则,因此造成一些编程员刻意避开使用刀具半径补偿。本文将从以下几个方面对刀具半径补偿在实际应用中出现的错误加以分析,并给出一些有益的建议,希望能够为读者提供解决此类问题的一些基本方法和思路。     

刀补功能及宏程序在数控加工中的应用

当数控系统具备刀具半径补偿功能时,数控程序只需按工件轮廓编写,加工时数控系统会自动计算刀心轨迹.数控铣削加工中的刀具半径补偿功能使编程大大简化,给编程者带来了很大的方便.     

刀具半径补偿在CNC编程中的错误及正确应用

在CNC编程中,合理地引入刀具半径补偿,可以使刀具轮廓轨迹的处理变得更简单.但是,由于使用刀具半径补偿要遵循很多相应法则,因此造成些编程员刻意避开使用刀具半径补偿.本文将从以下几个方面对刀具半径补偿在实际应用中出现的错误加以分析,并给出一些有益的建议,希望能够为读者提供解决此类问题的一些基本方法和思路.     

对数控铣削加工中刀具补偿的探讨

合理设置刀具半径补偿值,灵活应用刀具半径补偿功能,对简化数控铣削编程有着非常重要的意义。文章分析常用的刀具半径补偿方式,以FANUCOi系统为例,探讨C刀具半径补偿。     

数控系统的刀具数据处理中减段方法(二)

本文着重阐述了为解决加工过程中所选用的刀具不适而造成过切和干涉现象发生的可靠方法——减段处理。并对此方法的数学模型和实现过程作了详细叙述。该方法使加工时选用刀具与工件特殊轮廓不相关,使CNC系统中刀具半径补偿功能在使用上更加灵活、方便、加工更加可靠。     

刀具半径补偿中的矢量法

本文采用解析几何矢量法，推导出刀具半径补偿中直线与圆弧交点，并能迅速推广到圆弧与圆弧的交点，且可避免象限讨论。     

Computer numerical control for assuring the machining accuracy of contour milling

In this paper, a software technology for improving the machining accuracy in contour milling is discussed, in which the continuous path control is thoroughly investigated from the viewpoint of system synthesis, and the computer numerical control is effectively used. It is shown that the proposed “real-time cutter path rectification” offers an effective means to overcome the serious problem of the thermal deformation of workpieces. In this case, it is necessary to take many factors into consideration; the diversity of shapes, the change of cutting conditions, the unstable thermal situation, and so on. Therefore, the adaptive control is applied to compensate the thermal displacement of the contour during the cutting process. Relating to this subject, the effective cutter radius, which depends on cutter wear, is also evaluated in real-time operation; and the cutter diameter compensation is included in the “cutter path rectification”. In order to assure the machining accuracy, a new approach to contour measurement is proposed, in which the continuous path control by CNC system is used. It is certified through some experiments that the method proposed in this paper is useful to realize the flexible automation with high machining accuracy.     

基于Web的数控曲面磨床几何误差补偿技术

以误差补偿技术的网络化应用为目的展开研究,选取SMART-CNC数控曲面磨床为研究对象,运用多体理论,建立了磨床的运动模型,获得了与精密刀具轨迹相对应的逆变刀具路线或逆变数控指令的求解方法,在此基础开发了基于网络的误差补偿软件,构建了网络化误差补偿服务系统。仿真试验结果从理论上证明了本文建模方法的正确性和网络化应用方案的可行性。     

A multi-regional computation scheme in an AR-assisted in situ CNC simulation environment

Computer numerical control (CNC) simulation systems based on 3D graphics have been well researched and developed for NC tool path verification and optimization. Although widely used in the manufacturing industries, these CNC simulation systems are usually software-centric rather than machine tool-centric. The user has to adjust himself from the 3D graphic environment to the real machining environment. Augmented reality (AR) is a technology that supplements a real world with virtual information, where virtual information is augmented on to real objects. This paper builds on previous works of integrating the AR technology with a CNC machining environment using tracking and registration methodologies, with an emphasis on in situ simulation. Specifically configured for a 3-axis CNC machine, a multi-regional computation scheme is proposed to render a cutting simulation between a real cutter and a virtual workpiece, which can be conducted in situ to provide the machinist with a familiar and comprehensive environment. A hybrid tracking method and an NC code-adaptive cutter registration method are proposed and validated with experimental results. The experiments conducted show that this in situ simulation system can enhance the operator’s understanding and inspection of the machining process as the simulations are performed on real machines. The potential application of the proposed system is in training and machining simulation before performing actual machining operations.     

Optimal barrel cutter selection for the CNC machining of blisk

Barrel cutters have been widely used in the flank milling of blisk. In this paper, a new method is proposed to select an optimal barrel cutter in the interest of the high productivity in the CNC machining of blisk. The geometric properties and location of four types of barrel cutters are firstly introduced. Then the optimal size of the tool flute with a greater barrel radius is determined. Meanwhile, the local gouges and kinematic constraints of the CNC machine tool are also taken into account. Furthermore, in order to avoid the global interferences between the tool shaft and the blade in process, the center point of circular arc generatrix is adjusted. Finally, the tool shaft diameter is optimized to improve tool rigidity and avoid the global interferences between the tool shaft and the adjacent blades. The numerical examples prove that a feasible barrel cutter with the higher productivity can be obtained by the proposed method in this paper. Therefore, this method can be directly applied in the CNC machining of blisk or centrifugal impeller.     

基于刀具空间包围体算法的数控切削仿真

采用计算刀具空间包围体和刀具旋转体的方法来对仿真过程中的有效切削计算进行判断,刀具在一般运动情况下所占空间包围体的计算公式可由刀具的长度、半径以及刀具在任意时刻的刀位点、刀轴矢量来共同推导;刀具的旋转体范围可以通过刀具在当前时刻的刀轴矢量、母线方程以及刀具的半径、长度进行计算.该方法已经成功应用到基于OpenGL的VC6.0环境下所开发的五轴数控仿真系统中,实验结果表明,该方法能够提高有效切削率和减少切削计算耗时.     

CNC系统中曲面交线加工刀具轨迹直接插补

提出并实现了在CNC系统中完成曲面交线加工刀具轨迹直接插补的构想,可极大提高 CNC系统的几何轨迹控制能力和使用性能.给出了一个适用于球头刀加工的插补算法及其 加工误差估计,证明了算法的稳定性.理论分析和实践表明,该算法精度高、计算量小且稳 定.     

A computerised minimum distance algorithm for machining of sculptured surfaces

This paper presents a unique minimum distance algorithm for machining of sculptured surfaces on computer numerical control (CNC) machines. The algorithm has been used to develop a system that graphically simulates the cutter path of the defined surfaces and generates the required CNC programs. The paper presents the experimental results of the surface roughness, tool size, and computed numerical control (NC) points for various tolerance values used on several sculptured surfaces designed by the system and actually machined on a CNC machining centre using the generated NC program from the system.     

Open-architecture of CNC system and mirror milling technology for a 5-axis hybrid robot

This paper presents an open-architecture of CNC system and mirror milling technology for a new-type 5-axis hybrid robot named TriMule. The CNC system with dual CPUs is developed first to achieve human-computer interaction and motion control. Then, three key technologies are integrated in the system for improving the control quality, including singularity avoidance, feedforward control considering joint couplings and real-time error compensation by using externally mounted encoders. Based on these control technologies for single robot system, a collaborative machining strategy on the mirror milling system that consists of two TriMule robots is proposed to control the machining wall thickness of large thin-walled structural parts. Experiments on the TriMule robot and mirror milling system verify that the acceptable machining accuracy on the NAS test part and large thin-walled structural part can be ensured by using the developed CNC system and technologies. The root mean square of wall thickness error using the collaborative machining strategy can be 41.67% lower than the case without using the strategy.