采用国产数控系统进行机床再制造

我国普通机床保有量在300万台左右,如果按照每台再制造花费6万元计算,就意味着一个1800亿元的改造市场．即便不是每台普通机床都有改造的价值,但市场前景很广阔。     

浅谈普通钻床的数控改装

据资料介绍,我国拥有400多万台机床,绝大部分都是多年累积生产的普通机床。这些机床自动化程度不高,加工精度低,要想在短时期内用自动化程度高的设备大量更新,替代现有的机床,无论从资金还是从我国机床制造厂的生产能力都是不可行的。但尽快将我国现有的部分普通机床实现自动化和精密化改造又势在必行。为此,如何改造就成了我国现有设备技术改造迫切要求解决的重要课题。[1]分析　　(1)技术在过去的几十年里,金属切削机床的基本动作原理变化不大,但社会生产力特别是微电子技术、计算机技术的应用发展很快。反映到机床控制系统上,…     

普通车床的数控化改造

随着科学技术的发展,普通机床越来越不能满足市场的需求,其劳动强度大,危险性高,且不能满足现代科学的批量生产需要,越来越多的企业将普通机床逐渐转向数控化,因为数控机床可弥补普通机床的许多缺点,可实现加工精度高,多工序的集中化,自动报警,自动补偿及自动监控的功能。以车床的数控改造为例,介绍了机床数控改造的方法,包括其结构的改造设计,性能与精度的选择以及最后改造方案的确定。     

X62W铣床数控化改造——滚珠丝杠的选择

论文介绍X62W普通万能铣床改造成简易的数控铣床,由于普通机床是由齿轮传动,加工精度、稳定性比较差。因此,将机床原有的齿轮传动改为滚珠丝杠,并说明了滚珠丝杠选择方法以及计算过程。使数控化的X62W铣床的定位精度和重复定位精度明显提高,获得了明显的经济效益。     

CA6140车床的经济型数控改造

一、数控改造的实际意义 目前,各企业一般都有不少普通车床,完全用数控车床加以替换根本不可能。解决这个问题,必须走普通车床数控改造之路。日本大企业中有26％的机床经过数控化改造,而中小企业则占74％;美国有许多数控专业化公司为用户提供数控改造服务。我国拥有300万台机床,其中大量的是通用车床。因此,普通车床的数控改造,大有可为。 数控改造一般是指对普通车床某些部位作一定的改造,配上数控装置,从而使车床具有数控加工能力。     

充分发挥数显在传统制造技术改造和提升中的作用

中国在近代曾多次失去经济腾飞的机会,如果在21世纪再次失去,恐怕以后就没有机会了。我们的任务极其艰巨,而我国工业基础又相对薄弱,基础之一的制造业亟需进行改造和提升,其中机床行业作为装备工业(母机工业)的现状更是令人担忧。 我国机床拥有量占世界第一,其中劳动密集型的普通机床占96％以上,数控机床占1.9％;年产新机床12万台     

CA6140车床横向进给系统闭环控制设计

对现有的存在的大量的普通车床进行了数控化改造,并重新设计了进给、换刀和主轴传动系统,对进给系统的床鞍部分进行了改进,以适应现代化的车床加工要求。对原有繁琐的主轴传动系统,对比现有的小型数控机床,进行了整合与重新加工,尽可能的适应老式机床的改进。经过论证,数控化改造是可以实施并加以推广,对我国现存的大量老式机床有重要的参考意义。     

普通铣床的数控改造

利用微机改造普通机床，是目前设备改连急需解决的问题。文中介绍了采用JWK-15T型单片机系统改造普通铣床，改造后的普通铣床能保证加工零件的质量精度要求，特别是对复杂零件的加工，效果更为显著。     

如何选用数控机床及华亚数控机床性能

数控机床与传统普通机床的主要区别在于，它能够自动完成各种零件（不论是简单还是复杂）的机械加工；在操作上，数控机床对操作者的要求也比普通机床要来得低；由于数控机床采用现代数字控制技术，其生产效率远高于普通机床。由于数控机床的诸多优点，现在，数控机床在制造业的应用越来越广泛。     

试论普通机床加工轴的工艺设计

一般情况下,普通机床会采用轴传递扭矩、承受载荷,并支撑传动零部件,促使其处于相对位置。因此,根据轴的受力特点不同,主要通过阶梯轴结构,才能够进一步满足相关要求。在普通的机床轴进行加工时,效率都比较低,而且精度也很难满足设计要求。据此,本文主要对普通机床加工轴的工艺设计进行了深入探究。     

数控机床误差补偿技术及应用——几何误差补偿技术

利用多体系统运动学理论,通过分析低序体阵列、变换矩阵和运动方程,在相邻体之间引入位置误差和位移误差,建立了机床空间定位误差通用计算模型。基于激光测量提出机床的２１项几何误差参数辨识模型。在ＸＨ７１５加工中心上,对机床的空间几何误差进行理论计算,并进行补偿前后的对比实验,结果表明机床空间定位误差减小５０％以上,同时也表明利用误差补偿技术提高机床加工精度是有效的。     

Post-Processor Development for a Six Degree-of-Freedom Parallel-Link Machine Tool

A coordinate system with multiple non-orthogonal axes, defined for a parallel-link machine tool is very different from that for a conventional serial-type machine. Therefore, a special post-processor that can automatically transfer the cutter location data (CL-data) into machine specific NC commands is essential for real machining applications of a parallel-link machine tool. Parallel-link machine tools have been investigated by many previous workers. However, work on the theory of post-processors for this machine tool is very sparse, and most is focused on the orthogonal serial motion. The potential benefits of the parallel-link machine tools make work necessary and urgent on the transformation of the CL-data from a CAD/CAM system into NC commands for special parallel-link machine tools. A six degrees-of-freedom (DOF) parallel-link machine tool constructed as a 6-3-3 mechanism was selected in this work to investigate the theory of post-processing, and the effects of the cutter shapes and the machine construction on it. The parametric representations of different cutter shapes defined by the DIN standard were adopted in the work, increasing the usefulness of the post-processor theory developed. Specific parameters must be modified in the post-processor for different tools applied for real cutting. The tilt angle and yaw angle of the cutter, relative to the normal direction of the cutting surface, is also included in the theory. Finally, the NC code is generated using LabVIEW software, and simulations were performed to investigate the correctness based on several designed tool paths.     

A novel dynamic model for multiple configurations of machine tools using a coordinate transformation method

Virtual machine tools have been used widely for simulating designs in computer environments to determine optimal design parameters without the need for manufacturing prototypes. Machine tools include different multiple configurations that are designed to be suitable for the differing requirements of production. To date, studies on dynamic analysis have been limited to a few-axis machine tools of a specific configuration, such as a 3-axis milling machine or a 4-axis grinding machine. Here, we propose a novel method to focus on the dynamic analyses of multi-axis machines with differing multiple configurations. The motion equations for multiple degrees of freedom of linear and rotary axes are established by a Lagrange energy method, equilibrium equations, and Newton’s second law. This technique formulates the motion equations for each axis, and then further develops them for a multi-axis machine through a combination process and a transformation matrix. The library includes five dynamic model components, built to simulate 1236 different configurations of a machine tool. A dynamic analysis was applied to a control system to simulate the control signals of a virtual machine, which include stepped, ramped, curved, sinusoidal, and circular responses, and frequency response functions. The simulated and experimental results demonstrated that the method has high accuracy and reliability for one-, two-, and four-axis machine tools. Thus, this method can simulate the dynamic analyses of multi-axis machines and different multi-configurations without the need to build a specific configuration for each machine. It is recommended for selecting optimal motors, design parameters, and control parameters of the multiple configurations in a machine tool.     

数控机床的外观演进及其特征研究

对影响数控机床外观的各类因素予以归纳分析,提出建立数控机床外观演进图库的研究方法,在此基础上研究数控机床外观演进的过程,并予以概括梳理。以数控车床防护罩侧轮廓为例,进行了特征元素轮廓演进图的绘制与分析。最后总结了目前的数控机床外观设计与制造的发展特点。     

Dynamic Feedforward Control of a Novel 3-PSP 3-DOF Parallel Manipulator

Parallel manipulators with less than six degrees of freedom (DOF) have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that is particularly significant when these manipulators are used in high-speed machine tools. However, normal kinematic control method cannot satisfy the requirements of the control system. Many researchers use model-based dynamic control methods, such as the dynamic feedforward control method. However, these methods are rarely used in hybrid machine tools because of the complex dynamic model of the parallel manipulator. In order to study the dynamic control method of parallel manipulators, the dynamic feedforward control method is used in the dynamic control system of a 3-PSP (prismatic-spherical-prismatic) 3-DOF spatial parallel manipulator used as a spindle head in a high-speed hybrid machine tool. Using kinematic analysis as basis and the Newton-Euler method, we derive the dynamic model of the parallel manipulator. Furthermore, a model-based dynamic feedforward control system consisting of both kinematic control and dynamic control subsystems is established. The dynamic control subsystem consists of two modules. One is used to eliminate the influence of the dynamic characteristics of high-speed movement, and the other is used to eliminate the dynamic disturbances in the milling process. Finally, the simulation model of the dynamic feedforward control system of the 3-PSP parallel manipulator is constructed in Matlab/Simulink. The simulations of the control system eliminating the influence of the dynamic characteristics and dynamic disturbances are conducted. A comparative study between the simulations and the normal kinematic control method is also presented.The simulations prove that the dynamic feedforward control method effectively eliminates the influence of the dynamic disturbances and dynamic characteristics of the parallel manipulator on high-speed machine tools, and significantly improves the trajectory accuracy. This is the first attempt to introduce the dynamic feedfordward control method into the 3-PSP spatial parallel manipulator whose dynamic model is complex and provides a study basis for the real-time dynamic control of the high-speed hybrid machine tools.     

虚拟轴机床数控加工后置处理

在分析研究了虚拟轴机床的结构和坐标转换关系的基础上,针对清华大学研制的6-PSS型虚拟轴机床,提出了刀位后处理计算方法,包括刀轴矢量与机床坐标夹角的计算和NC数据的计算;为编制虚拟轴机床数控后处理程序提供一条捷径.     

五轴联动加减速控制软件研究

五轴五联动数控机床主要应用于自由曲面的加工。但五轴联动所涉及的加减速就目前所见资料而言，未能得到很好解决。本文重点分析了刀轴有两个旋转自由度(如B、C)的五轴联动的加减速问题。结果表明经研制的加减速模块在南京四开电子企业有限公司的五轴五联动数控机床上得到较好应用。     

Diagnosing the cause of operational faults in machine tools with an open architecture CNC

The conventional computerized numerical controller (CNC) of machine tools has been increasingly replaced by a PC-based open architecture CNC (OAC) that is independent of a CNC vendor. The OAC and machine tools with an OAC have led to a convenient environment in which user-defined applications can be efficiently implemented within a CNC. This paper proposes a method of diagnosing the cause of operational faults. The method is based on the status of a programmable logic controller in machine tools with an OAC. An operational fault is defined as a disability that occurs during the normal operation of machine tools. Operational faults constitute more than 70 percent of all faults and are also unpredictable because most of them occur without any warning. To quickly and correctly diagnose the cause of an operational fault, two diagnostic models are proposed: the switching function and the step switching function. The cause of the fault is logically diagnosed through a fault diagnosis system using diagnostic models. A suitable interface environment between a CNC and developed application modules is constructed to implement the diagnostic functions in the CNC domain. The results of the diagnosis were displayed on a CNC monitor for machine operators and transmitted to a remote site through a Web browser. The proposed diagnostic method and its results were useful to unskilled machine operators and reduced the machine downtime.     

数控机床位置误差建模与补偿

基于空间机构的分析与综合,利用机器人运动学中的齐次变换,提出了数控机床几何误差的一般模型,并针对一台立式加工中心,验证了模型的正确性。所提出的模型和结论,可推广应用于多轴数控机床的误差建模与补偿。     

Developing a postprocessor for three types of five-axis machine tools

This paper presents a postprocessor capable of converting cutter location (CL) data to machine control data for three typical five-axis machine tools to establish an interface between computer-aided manufacturing (CAM) systems and numerically controlled (NC) machines. The analytical equations for NC data are obtained using the homogeneous coordinate transformation matrix and inverse kinematics. In addition, the developed postprocessor method is implemented through a trial-cut on a five-axis machine and verified on the coordinate measurement machine. Experimental results confirmed the effectiveness of the proposed postprocessor method which can be used to integrate the various five-axis machine tools employed in manufacturing systems.