PWM控制节能式线切割脉冲电源补偿网络研究

在分析脉冲电源放电电流闭环控制子电路的基础上,利用状态空间平均法建立了脉冲电源系统的开环传递函数。对脉冲电源电流采样电路补偿网络进行了PID设计,从而改善了脉冲电源放电电流的动态特性,通过实际应用,证明该脉冲电源的电能利用率可以达到70%左右,满足了脉冲电源的加工需要。     

闭环伺服系统的动态性能分析

在数控机床中 ,伺服系统是数控装置和机床的中间联接环节 ,是数控系统的重要组成部分。伺服系统接受来自伺服控制器的进给脉冲 ,经变换和放大后转化为机床工作台的位移 ,使工作台跟随指令脉冲移动。文章研究了闭环伺服系统的动态性能分析。该研究结果为伺服数控加工系统的快速响应及其加工精度提供理论基础。     

逆变式电火花加工脉冲电源的单片机控制方法

介绍了逆变式电火花加工脉冲电源的单片机控制方法，具体阐述了电源参数的键盘设定及显示、等电流脉宽加工脉冲的产生、加工电流峰值设定，并针对具有良好人机交互界面的单片机系统极端恶劣的工作环境，阐述了抗干扰的软件和硬件措施。     

数控铣床丝杆间隙对加工的影响分析

数控机床随着使用时间的增加,丝杆会出现磨损等情况,其间隙会不断增大,导致机床加工误差增大。本文详细分析数控铣床的丝杆间隙在不同加工情况下对加工精度的影响,并提出几种解决方法,以降低这种影响,提高零件的加工精度。     

简易数控直流电源的设计与制作——获’94首届全国大学生电子设计竞赛北京赛区三等奖

数控电源与常规可调电源不同,它通过数字量控制输出电压,因此其输出电压不是连续可调,而是步进增减的,按竞赛题意要求,输出电压应从0V调到9.9V,每步0.1V,总计99步。 1.设计思路要求数控电源最大能输出500mA电流,我们设想在三端可调电源LM317的基础上,通过改变其公共端对地电位的办法来调节输出电压。因为LM317的固定输出电压为 1.25V,如能使LM317公共端对输出地在不加控制脉冲时为-1.25V。     

“变脉冲当量进给”技术及其应用

本文针对我国目前常用的数控线切割机床进给控制系统所存在的不足之处，提出了改进措施，用“变脉冲当量进给”技术取代原有电火花线切割机床的控制系统，作者将这一技术成功地应用到数控线切割加工中，很方便地实现了椭圆，抛物线，阿基米德螺旋线，标准渐开线齿廓的电火花线切割加工。“变脉冲当量进给”技术在电火花线切割加工中的应用，大大地简化了高次曲线和复杂曲面线切割加工，解决了线切割机床空载时快速进给，加工后快速回退，切割时小步距离进给不能兼顾的矛盾，提高了线切割加工机床的加工稳定性，有效地扩大了线切割机床的应用范围。     

一种快速直线脉冲增量插补算法

提出了一种应用于数控加工的快速空间直线脉冲增量插补算法。该算法在插补过程中只进行整数运算,每次插补计算可以得到两个进给步的三坐标轴进给脉冲增量。提高了直线插补的运算效率,而误差小于0. 707个脉冲当量。     

基于VB.net的数控实验平台的设计与开发

数控实验平台是一套通过接收计算机控制软件发出的脉冲来实现描绘编程图形以模拟数控机床加工零件的教学实验设备.本文介绍了其设计过程,并着重对数控实验平台的软件部分进行了研究.软件部分用VB. net实现,编写实验平台的软件控制系统,系统包括人机界面、译码函数、插补函数和附加功能等.     

电火花成型机床的单片机控制

本文介绍由８０３１单片微机组成的脉冲电源控制器，用以改造现有的电火花成型机床，提高了加工产品的质量。     

数控加工仿真技术研究综述

数控加工仿真技术可以形象、直观地模拟数控加工的全过程,为验证数控加工程序的可靠性及预测切削加工过程提供了强有力的工具。介绍了数控加工仿真的关键技术——几何仿真技术、物理仿真技术和图像可视化技术,并分别对此3个数控加工仿真关键技术的研究成果进行分析评述,最后提出了数控加工仿真技术的发展趋势。     

A Z-map update method for linearly moving tools

In numerically controlled (NC) machining simulation, a Z-map has been frequently used for representing the workpiece. Since the Z-map is usually represented by a set of z-axis aligned vectors, the machining process can be simulated through calculating the intersection points between the vectors and the surface swept by a machining tool. In this paper, we present an efficient method to calculate those intersection points when automatically programmed tool-type tools move along a linear tool path. Each of the intersection points can be expressed as the solution of a system of non-linear equations. We transform this system of equations into a single-variable equation, and calculate the candidate interval in which the unique solution exists. We prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the non-linear equations within a given precision. The whole process of NC simulation is achieved by updating the Z-map properly. Our method can improve accuracy greatly while increasing processing time negligibly in comparison with previous Z-map update methods, making it possible to verify the tool path more accurately and reliably.     

An artificial immune system approach to CNC tool path generation

Reduced machining time and increased accuracy for a sculptured surface are both very important when producing complicated parts, so, the step-size and tool-path interval are essential components in high-speed and high-resolution machining. If they are too small, the machining time will increase, whereas if they are too large, rough surfaces will result. In particular, the machining time, which is a key factor in high-speed machining, is affected by the tool-path interval more than the step size. The present paper introduces a ‘system software’ developed to reduce machining time and increased accuracy for a sculptured surface with Non-Uniform Rational B-Spline (NURBS) patches. The system is mainly based on a new and a powerful artificial intelligence (AI) tool, called artificial immune systems (AIS). It is implemented using C programming language on a PC. It can be used as stand alone system or as the integrated module of a CNC machine tool. With the use of AIS, the impact and power of AI techniques have been reflected on the performance of the tool path optimization system. The methodology of the developed tool path optimization system is illustrated with practical examples in this paper.     

An exact solution to the TLP problem in an NC machine

This paper considers a job sequencing problem for a single numerical controlled machining center. It is assumed that all the considered jobs must be processed on a single machine provided with a tool magazine with C positions, that no job requires more than C tools to be completely machined and that the tools may be loaded and unloaded from the tool magazine only when the machining operations for each job are completed. The decisional problem is referred to as the tool loading problem (TLP) and it determines the jobs machining sequence as well as the tools to load in the machine tool magazine before the machining operations on each job may start. In industrial cases where the tool switching time is both significant relative to job processing time and proportional to the number of tool switches, the performance criterion is the minimization of the number of tool switches. This paper demonstrates that the TLP is a symmetric sequencing problem. The authors enrich a branch-and-bound algorithm proposed in literature for the TLP with the new symmetric formulation. Computational experiments show the significant improvement obtained by the novel symmetric formulation of the TLP.     

基于STM32微控制器的高频脉宽调制器的设计

高频脉冲电源对提高微细电解加工的工艺性有着重要的作用,而脉宽调制器经驱动电路生成IGBT控制信号决定着高频高压脉冲电源的输出频率及占空比;针对电解加工工艺的特殊性,创新性地提出基于32位微型控制器芯片STM32F103RCT6为核心的调频调占空比的方案;根据脉冲频率、占空比可调的要求,完成了脉宽调制器的软硬件设计,通过编译运行程序代码进行一系列的调频、调占空比实验并利用示波器采集两路输出的PWM波形;实验表明,自行研制的脉宽调制器能稳定地调节两路PWM控制信号的频率及占空比,验证了装置及设计的合理性。     

Dynamic visual servo control of a 4-axis joint tool to track image trajectories during machining complex shapes

A large part of the new generation of computer numerical control systems has adopted an architecture based on robotic systems. This architecture improves the implementation of many manufacturing processes in terms of flexibility, efficiency, accuracy and velocity. This paper presents a 4-axis robot tool based on a joint structure whose primary use is to perform complex machining shapes in some non-contact processes. A new dynamic visual controller is proposed in order to control the 4-axis joint structure, where image information is used in the control loop to guide the robot tool in the machining task. In addition, this controller eliminates the chaotic joint behavior which appears during tracking of the quasi-repetitive trajectories required in machining processes. Moreover, this robot tool can be coupled to a manipulator robot in order to form a multi-robot platform for complex manufacturing tasks. Therefore, the robot tool could perform a machining task using a piece grasped from the workspace by a manipulator robot. This manipulator robot could be guided by using visual information given by the robot tool, thereby obtaining an intelligent multi-robot platform controlled by only one camera.     

Batch mode micro-electro-discharge machining

This paper describes a micro-electro-discharge machining (micro-EDM) technique that uses electrode arrays to achieve high parallelism and throughput in the machining. It explores constraints in the fabrication and usage of high aspect ratio LIGA-fabricated electrode arrays, as well as the limits imposed by the pulse discharge circuits on machining rates. An array of 400 Cu electrodes with 20 μm diameter was used to machine perforations in 50-μm-thick stainless steel. To increase the spatial and temporal multiplicity of discharge pulses, arrays of electrodes with lithographically fabricated interconnect and block-wise independent pulse control resistance-capacitance (RC) circuits are used, resulting in >100× improvement in throughput compared to single electrodes. However, it was found to compromise surface smoothness. A modified pulse generation scheme that exploits the parasitic capacitance of the interconnect offers similarly high machining rates and is more amenable to integration. Stainless steel workpieces of 100 μm thickness were machined by 100 μm×100 μm square cross-section electrodes using in 85 s using an 80-V power supply. Surface smoothness was unaffected by electrode multiplicity. Using electrode arrays with four circuits, batch production of 36 WC-Co gears with 300 μm outside diameter and 70 μm thickness in 15 min is demonstrated     

Numerical analysis of the tool wear effect in the machining induced residual stresses

Machining is a dynamic process involving coupled phenomena: high strain and strain rate and high temperature. Prediction of machining induced residual stresses is an interesting objective at the manufacturing processes modelling field. Tool wear results in a change of tool geometry affecting thermo-mechanical phenomena and thus has a significant effect on residual stresses. The experimental study of the tool wear influence in residual stresses is difficult due to the need of controlling wear evolution during cutting. Also the involved phenomena make the analysis extremely difficult. On the other hand, Finite Element Analysis (FEA) is a powerful tool used to simulate cutting processes, allowing the analysis of different parameters influent on machining induced residual stresses.The aim of this work is to develop and to validate a numerical model to analyse the tool wear effect in machining induced residual stresses. Main advantages of the model presented in this work are, reduced mesh distortion, the possibility to simulate long length machined surface and time-efficiency. The model was validated with experimental tests carried out with controlled worn geometry generated by electro-discharge machining (EDM). The model was applied to predict machining induced residual stresses in AISI 316 L and reasonable agreement with experimental results were found.     

数控仿真中的实时碰撞检测算法的研究

碰撞干涉检测是数控加工仿真中的重要组成,文章提出了一种实现数控仿真加工的实时碰撞检测算法,该方法是通过测试线与刀具扫掠体包络面求交的交点来判断刀具或刀柄在加工过程中是否和夹具发生了碰撞,以及碰撞发生在哪些控制代码所对应的刀具移动上;算法的关键在于实时性,满足了数控加工过程中的实时碰撞检测,同时也给出了实例说明了算法的有效性。     

镁合金微弧氧化大功率脉冲电源的研制

介绍一种用于镁合金微弧氧化表面处理的脉冲电源数字控制系统设计.该电源采用三相半波晶闸管整流电路,I G B T进行直流斩波;根据电流电压反馈信号计算偏差,进行数字P I调节获得恒流、恒压输出特性;控制系统通过2 0 m A电流环异步串行通讯接口与人机界面交换数据.研制的样机在运行中表现出良好的稳定性和可靠性.     

Minimum void length scale control in level set topology optimization subject to machining radii

This paper presents a minimum void length scale control method for structural topology optimization. Void length scale control has been actively investigated for decades, which intends to ensure the topology design manufacturable given the machining tool access. However, only a single lower bound has been applied in existing methods, which does not fit the multi-stage rough-to-finish machining. To fix this issue, the proposed minimum void length scale control method employs double lower bounds which corresponds to the rough and finish machining operations, respectively. This method has been implemented under the level set framework. For technical details, the rough machining lower bound is satisfied by developing a signed distance-related constraint, which ensures enough space for the rough machining tool movement and thus, guarantees the machining efficiency. The finish machining lower bound is addressed through the curvature flow control, which ensures the small features manufacturable and also a good finish dimension and surface. Through a few numerical case studies, it is proven that the minimum void length scale can be effectively controlled without sacrificing much of the structural performance.