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DZ242电火花线切割机电气控制系统的设计,毕业设计
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电 火 花 线 切 割 机 电气系统设计 姓 名：刘洪义 专 业：自动化 指导教师：白文峰 nts# 1.本文研究的目的和意义 从老式的电火花线切割机到此时的数控电火花线切割机，不论从走丝方式还是控制方式上都得到了很大的改进，最重要的就是数字程序控制取代了过去的模仿形控制和光电跟踪控制。 当电火花线切割机生产工艺要求的提高，原有的线切割机电气系统将不能满足生产工艺的要求。而设计的电气控制系统的好坏将直接影响到整台切割机的生产工艺系数。 nts# 电火花线切割机工作原理 电火花线切割加工的工作过程主要包括以下三个部分 1.电极丝与工件之间的脉冲放电。 2.电极丝沿其轴向（垂直或 z方向）做走丝运动。 3.工件对于电极丝在 X.Y平面内做数控运动。 nts# 2.电火花线切割机电气系统的设计 1.根据电火花线切割的工作原理，采用微型计算机来控制步进电机，使电极丝按照事先所编订好的程序图形做运动。系统具有自动显示功能，由键盘控制系统启、停及选择需要程序图形等功能。 2.主要几项技术指标 : （ 1）加工轨迹：任意平面曲线及直线 （ 2）加工精度：轮廓线 - 0.01毫米 圆弧随圆度 - 0.02毫米 nts# 3. 系统结构框图 矩 阵 式键 盘 输 入A T 8 9 C 5 56 位 L E D动 态 显 示并 行 接 口 电 路 驱 动 电 路步 进 电 机位 置 检 测 反 馈 装 置nts# 4.控制单元的设计 nts# 5.系统主电路的设计 系统的主电路主要是由芯片 CH250 和步进电机组成，步进电机在驱动脉冲的作用下，实现其功能， CH250输出双三拍，单六拍等脉冲信号，供不同性能步进电机驱动需要，适当施加有关引出端的电平，可控制步进电机正转和反转。当CPU给定 CH250以驱动信号， CH250将信号分配给电机驱动电路 nts# nts# 6.位置检测反馈装置 （ 1） 光栅传感器的选择 QH-200型光栅尺实物图 光栅传感器输出两路相位相差为 90的方波信号 A和 B nts# （ 2） .四倍频电路 nts# 采用 10MB晶振产生全局时钟 CLK，假设信号 A超前于B时代表指示光栅朝某一方向移动， A滞后于 B时表示光栅的反方向移动。 A， B信号分别经第一级 D触发器后变为 A， B信号，再经过第二级 D触发器后变为 A ， B 信号。 D触发器对信号进行整形，消除了输入信号中的尖脉冲影响，在后续倍频电路中不再使用原始信号 A， B，因而提高了系统的抗干扰性能。在四倍频辨向电路中，采用组合时序逻辑器件对 A A ， B B 信号进行逻辑组合得到两路输出脉冲：当 A超前于 B时， ADD为加计数脉冲，MIMUS保持高电平；反之，当 A滞后于 B时， ADD保持高电平 ,MINUS为减计数脉冲 nts# 7.外围电路的设计 （ 1）矩阵式键盘和 6LED显示电路 8279是一种管理键盘和 LED显示器的专用可编程控制芯片。它能对 8位共阴极 LED显示器或64个 LED发光管进行管理和驱动，同时能对多达 8又 8的键盘矩阵的按键情况进行监视，具有自动消除键抖动并识别按键代码的功能，从而可以提高 CPU工作的效率。因此，在微型控制器、智能仪表、控制面板和家用电器等领域中日益获得广泛的应用。 nts# (2)显示电路硬件图 nts# 8.软件设计 出错 Y 系统上电复位 系统初始化 工作状态选择 编辑？ 空运行 ? 自动？ 手动？ 回零？ 对刀？ 编辑处理 空运行处理 手动处理 回零处理 对刀处理 调入零件程序对零件程序进行编码 查阅键盘 启动并运行差补控制程序 启动键按下否 差补程序执行完 Y Y Y Y Y Y Y N N N N N N N N nts# -X向直线闭环调节 确定运动方向速度行程 Nx 行程 电机沿 -X向输出一步延时，采样，得 -X向移动量负 修改行程 Nx Nx+正 -负 返回 Nx ? N Y 闭环调节子程序程序 ： nts# 第一象限直线差补运算程序流程图： 开始 取线性代码（ LCD） 判其它线型 +Y进给 +X进给 置偏差初值（ FM=0） 停止 判线型是 L1? FM0? =0? FM FM-Ye FM FM+Xe I -1 N N Y Y N Y nts# 全文总结 经过三个月的毕业设计 ， 使我对电火花线切割机的电气部分有了初步的认识 ，对本专业又有了更进一步的了解 。 由于本人能力有限 ， 本文所介绍的电火花电气系统还不够完善 ， 还有很多不足之处 ， 希望大家能多提宝贵意见 ， 来慢慢完善这个系统 。 nts# 谢谢各位老师四年来对我们的教育和培养！ 祝各位老师在以后的工作中 一帆风顺，万事如意！ nts摘 要 随着数控线切割机床应用的不断扩大，机床本身也 得 到了不断的发展。十多年前，“负旦型”数控线切割机床首先应用 于实际生产，最早控制台是由晶体管分离元件组装而成，逐渐 采用集成电路，现在正向采用微型计算机控制的方向发展，因此本 论文设计的“电火花线切割机的 电气控制系统 ”是以 89C55 单片机作为控制核心，步进电机作为驱动电机，光栅作为位移 检测元件而构成的一个闭环控制系统。 电火花线切割机的核心技术就是控制位移量的精度。本文采用了 QH-200 型 光栅尺 传感器来检测位移量，通过 ATMEL 公司的 89C55 作为控制元件， 输出的两路方波，送入单片机，通过 CH250 来驱动电机，控制电机移动， 完成 想要的 工件 图形。 本文设计的 电火花电气系统，控制 精度及 检测 精度都能达到 0.01 毫米 。 系统具有 加工状态 自动显示功能，由键盘控制系统启、停以及对 位移量 进行设定。 关键词 ： 电火花 线切割 单片机 步进电机 ntsAbstract Along with the numerical control line cutting engine bed application unceasing expansion, engine bed itself also arrived the unceasing development. More than ten years ago, “the negative day” the numerical control line cutting engine bed first applies and the actual production, starts the control bench is uses the transistor separative element assembly to become, after but uses the integrated circuit, now to is using the direction which the microcomputer controls to develop, Therefore this definition design “the electrical fire colored thread cutter automatic control” is by 8031 shrapnel machine took the control core, step-by-steps the electrical machinery achievement to actuate the electrical machinery, the diffraction grating a closed-loop control system which constitutes as the position examination part. WEDM the core technology is to control the accuracy of displacement. In this paper, the QH-200-foot grating sensors to detect displacement through ATMELs 89C55 as a control device, the output of two-way square, into the microcontroller, through CH250 to drive motor, control motor movement, would like to complete To the workpiece graphics. In this paper, the design of the EDM electrical system, control accuracy and precision of detection to achieve 0.01 MM. State system has automatically display processing functions from the keyboard control system Kai, stopped and the displacement of a set. KeyWord： electrical sparkle linear cutting microcomputer Stepper motor ntsIn the frequency changer movement process exists question and countermeasure This paper analyzed the problem of harmonic wave, matching of load and calorification for inverters in running, and made the relativelythe measure. Keywords: inverter harmonic wave loading calorification 1 foreword has entered the Chinese market since the 80s general frequency changers, obtained the extremely widespread application in the short several year time.At present, the general frequency changer by its merits and so on intellectualization, digitization, network more and more receives peoples favor.Along with the general frequency changer application scope expansion, the question which exposes more and more are also many, mainly has following several aspects: Overtone question Frequency changer matching of load question Gave off heat above the question these questions already to cause the related control section and the factory and mine attention and has formulated the related technical standard.If the overtone question, our country and in 1993 passed “the electrical power system overtone management temporary provisions” in 1984 and the GB/T-14549-93 standard, with limits the power supply system and the current collector overtone pollution. In view of the above question, this article carried on has analyzed and proposed the solution and the countermeasure. 2 overtone questions and the countermeasure general frequency changer main circuit form is composed generally by three parts: Rectification part, contravariant part and filter part.The rectification part for the three-phase bridge type uncontrolled rectifier, the invertor part is the IGBT three-phase bridge type invertor, also the output is the PWM profile.Regarding the bipolarity modulation frequency ntschanger. because the general frequency changer rectification part uses the diode uncontrolled bridge type leveling circuit, the middle filter part uses the big electric capacity to take the filter, therefore the rectifier input current in fact is the capacitor charging current, assumes a higher more and precipitous pulse wave, its harmonic component is big.For the harmonic cancellation, may use following countermeasure: Increase frequency changer electric power supply internal resistance In the usual situation, the power equipment internal resistance may play the cushion frequency changer cocurrent filter electric capacity reactive power role.This kind of internal resistance is the transformer short-circuit impedance.When power source capacity relative frequency changer capacity hour, then internal resistance value relative bigger, the harmonic content is smaller; When the power source capacity relative frequency changer capacity is bigger, then internal resistance value relative bigger, the harmonic content is bigger. Regarding Mitsubishi FR-F540 series frequency changer, when internal resistance is 4%, may play the very good harmonic suppression role .Therefore time choice frequency changer electric power supply transformer, best choice short-circuit impedance big transformer. (2) Installs the reactor to install the reactor in fact from exterior increase frequency changer electric power supply internal resistance. Installs the direct current reactor in the frequency changer exchange side installment exchange reactor or in the frequency changer direct current side, or also installs, suppression harmonic current. The table as soon as listed the Mitsubishi FR-A540 frequency changer to install the reactor and not to install the reactor the content comparative table. (3) The transformer heterogeneity movement general frequency changer rectification part is six pulse waves rectifiers, therefore produces the overtone is bigger. If applies the transformer the heterogeneity movement, causes mutually to miss 30 like Y- , - the combination two transformers constitution is equal to 12 pulse waves effects may reduce the harmonic current 28%, played the very good harmonic suppression role. nts(4) Adjusts the frequency changer the carrier compared to from (1), (2), (3) the formula may see, so long as the carrier enough is bigger than, comparatively 低次 the overtone may effectively suppress, specially the reference wave peak-to-peak value and the carrier peak-to-peak value are smaller than 1 oclock, 13 below odd number overtone no longer appears. (5) Special-purpose filter this special-purpose filter uses in to examine the frequency changer harmonic current the peak-to-peak value and the phase, and produces to be same also the phase just right opposite electric current with the harmonic current peak-to-peak value, passes through in the frequency changer, thus may extremely effectively absorb the harmonic current. 3 matchings of load question and its the countermeasure produce machinery the type to be many, performance and technological requirement respectively different, its torque characteristics is complex, roughly divides into three kind of types: The permanent torque loading, the air blower pump a kind of load and the permanent power load. In view of the different load type, should choose the different type the frequency changer. (1) The permanent torque loading permanent torque loading is refers to the load moment to have nothing to do with with the rotational speed, under any rotational speed, the torque maintains constantly. The permanent torque loading divides into the friction class load and the potential energy type load. About friction class load starting moment general request nominal torque 150%, about brake torque general request nominal torque 100%, therefore the frequency changer should choose these to have the constant torque characteristics, and starts and the brake torque all quite big, the overload time is long and the overload capacity big frequency changer. If Mitsubishi frequency changer FR-A540 series. The potential energy type load generally requests the big starting moment and the energy back coupling function, can fast realize is reversing, the frequency changer should choose has four quadrants running ability the frequency changer. If Mitsubishi frequency changer FR-A241 series. (2) air blower pumps the kind of load air blower to pump a kind of load is present industry field application most ntsequipment, although pumps the gentle breeze machine characteristic many and varied, but mainly by the centrifugal pump and the centrifugal air blower application primarily, the general frequency changer are most in this kind of load application. The air blower pumps a kind of load is one square torque loading, its rotational speed n and current capacity Q. May see from the previous type, the air blower load system rotation inertia computation is wants extremely again. When frequency changer concrete design, presses down the type computed result, carries on the suitable revision, starts when the frequency changer in the situation which does not have the class to trip decelerates with the frequency changer when does not occur 过电压 trips, choice shortest time. Pumps a kind of load in the actual movement process, is easy to have the buzz, the build the pressure and the water hangs the effect, therefore time frequency changer shaping, must choose is suitable for to pump a kind of load the frequency changer also the frequency changer when the function hypothesis must aim at the above question to carry on alone establishes: Buzz: Surveys easily to have the buzz frequency spot, jumps the frequency through the hypothesis and the width, avoids the phylogeny resonance effect. Build the pressure: Pumps a kind of load when the low speed movement, causes the current capacity as a result of the system build the pressure is zero, thus creates pumps burn outs. When frequency changer function hypothesis, through defines the frequency changer the most low frequency, but had defined pumps the current capacity the critical point place system lowest rotational speed, this has avoided this kind of phenomenon occurrence. The water hangs the effect: Pumps a kind of load when the sudden power failure, as a result of pumps in the pipeline the liquid gravity to flow backwards. If the check valve is lax or does not have the check valve, will cause the electrical machinery reverse, will cause the frequency changer because of the electrical machinery electricity generation to break down to report to the police burn outs. When frequency changer system design, should cause the frequency changer to stop according to the deceleration curve, separates the main circuit electricity again after electrical machinery dead stop, or the ntshypothesis the power failure decelerates stops the function, has like this avoided this phenomenon occurrence. (3) The permanent power load permanent power load is refers to the torque roughly with to transfer the intensive inverse ratio the load, like coiler, opening a book machine and so on. Actuates the permanent power load when using the frequency changer, should be, the usual consideration which speaking of the certain speed change scope below some rotational speed selects the permanent torque velocity modulation method, but when is higher than this rotational speed only then selects the permanent power velocity modulation method. We usually are called this rotational speed spot the base frequency, this point correspondence voltage for frequency changer output rated voltage. Theoretically speaking, must want to realize in the true significance permanent power control, Frequency changer output frequency f and output voltage U must follow the U2/f=const coordination control, but this is does not permit in the actual frequency changer movement process, because above the base frequency, the frequency changer output voltage cannot increase along with its output frequency, only can maintain the rated voltage,therefore only can be in one kind of approximate significance permanent power control. 4 gives off heat the question and its the countermeasure Frequency changer giving off heat is produces by the internal loss. In the frequency changer in each part of losses mainly by the main circuit primarily, approximately composes 98%, the control circuit accounts for 2%. In order to guarantee the frequency changer normal reliable movement, must carry on the radiation to the frequency changer, usually uses following method: (1) Uses the ventilator radiation: The frequency changer internal installation ventilator may carry off the frequency changer box body interior radiation, if the ventilator cannot the normal work, be supposed to stop the frequency changer movement immediately. (2) Reduces installs the ambient temperature: Because the frequency changer is the electronic installation, content electron Yuan, electrolysis ntselectric capacity and so on, therefore the temperature quite is big to its life influence. The general frequency changer environment operating temperature generally requests -10 -50 , if can take the measure to reduce the frequency changer operating temperature as far as possible, then the frequency changer service life lengthens, the performance quite is also stable. We adopt two methods: One method is the construction independent frequency changer low pressure, the interior installs the air conditioning, the maintenance low pressure the temperature in +15 +20 between. Another method is the frequency changer installment space needs to satisfy the frequency changer instruction for use the request. Above talks about the frequency changer gives off heat is refers to the frequency changer in the fixed scope the normal operation loss. When the frequency changer has the unusual movement (for example class, crosses pressure, the loss which overload and so on) produces must avoid this kind of phenomenon through the normal shaping the occurrence. Pumps a kind of load regarding the air blower, when we choose Mitsubishi frequency changer FR-F540, its overload can be 1.20%/6 million second, its overload cycle is 300 seconds, in other words, when the frequency changer is opposite to its rated load 120% overload, it the duration is 60 seconds, and does not allow within 300 seconds to appear the second overload. When the frequency changer appears the overload, the power unit because it has flowed the excess current elevates temperature, causes the frequency changer heat, by now had to cause its temperature decrease to cause the frequency changer the hot protection movement as soon as possible to eliminate, this undercooling was the frequency changer overload cycle. The different frequency changer, its overload multiple, the overload time and the overload cycle are not same, and its overload multiple bigger,the overload time is shorter, Electrical machinery actuates which regarding the frequency changer, may divide into two kinds according to its working condition: Long lasting work ntssystem and repetition short-term operation system. The long lasting work system electrical machinery may according to its name brand stipulation data long-term movement. In view of this kind of load, the frequency changer may carry on the shaping according to the electrical machinery data plate data, like continuous running oil pump, if its electrical machinery power is time 22kW, may choose the FR-F540-22k frequency changer then. The repetition short-term operation system electrical machinery, its characteristic is the duplication and the short time, namely the electrical machinery operating time and the idle time time carry on in turn, moreover quite is all short, sum of the two, according to the country stipulated does not have to surpass for 60 seconds. The repetition short-term operation system electrical machinery permits its overload also has certainly certainly Temperature elevation. This time, if chooses the frequency changer according to the electrical machinery data plate data, inevitably will create the frequency changer the damage. In view of this kind of load, the frequency changer in the reference electrical machinery data plate data situation must according to the electrical machinery load diagram and the frequency changer overload multiple, the overload time, the overload cycle comes the shaping. If duplicates the short-time movement the elevator, its electrical machinery power is 18.5kW, may choose the FR-A540-22k frequency changer. 5 conclusions this article through has the problem to the general frequency changer movement process in the analysis, proposed solves these questions actual countermeasures, along with the new technology and the new theory unceasingly on the frequency changer application, these questions which the frequency changer exists hopefully and compensates through the frequency changer itself function solves. Unceasingly enhance along with the industry scene and the social environment to the frequency changer request, meets the actual needs the falsehood the green the frequency changer also to be able soon to appear on the market. nts6 references (1) Han Anrong General frequency changer and its application Beijing: Mechanical industry publishing house, 2,000 (2)Mitsubishi frequency conversion velometer FR-A500 users manual (3)Mitsubishi frequency conversion velometer FR-F500 users manual nts 在频率变 运行过程中 存在的疑问和对策 本文针对变频器运行过程中存在的谐波问题、负载匹配问题和发热问题，进行了分析，并提出了相对应的解决方案 自从 80 年代以来频 率变进入中国市场 , 在那短好几年时间获得广泛的应用。目前，通用变频器以其智能化、数字化、网络化等优点 得到 越来越受到人们 好评 。随着通用变频器应用范围的扩大，暴露出来的问题也越来越多，主要有以下几方面 : 偕波问题 频率变负荷相配问题 发热问题 以上问题已经引起那相关的控制区段和工厂矿的注意而且制定那相关的技术上的标准。如偕波问题 , 我们的国家和以 1993 年 电力系统偕波问题管理暂时的规定 在 1984 年 GB/T-14549-93标准 , 与极限力量补给系统和现在的搜集家泛音污染。 对于以上的 问题 , 本 文章 进行了分析和提出 解决和对策。 2 谐波问题 和对策 通用变频器的主电路形式一般由三部分组成 :整流部分、逆变部分和滤波部分。整流部分为三相桥式不可控整流器，逆变器部分为 IGBT三相桥式逆变器，且输出为 PWM波形。通用变频器的输出电压中确实含有除基波以外的其他谐波。较低次谐波通常对电机负载影响较大，引起转矩脉动，而较高的谐波又使变频器输出电缆的漏电流增加，使电机出力不足，故变频器输出的高低次谐波都必须抑制。 因为一般的 通用变频器的整流部分采用二极管不可控桥式整流电路 , 中间滤波部分采用大电容作为滤 波器，所以整流器的输入电流实际上是电容器的充电电流，呈较为陡峻的脉冲波，其谐波分量较大。为了消除谐波，可采用以下对策 : 增加 变频器 电 源 内在的 阻抗 在平常的情形中 , 电源 设备内在的抵抗可能 起到缓冲变频器直流滤波电容的无功功率的 角色。这种内 阻 抗是变压器 发生短路阻抗的 。 当电源容量相对变频器容量越小时，则内阻抗值相对越大，谐 波含量越小；电源容量相对变频器容量越大时，则内阻抗值相对越大，谐波含量越大。对于三菱 FR-F540系列变频器，当电源内nts阻为 4%时，可以起到很好的谐波抑制作用。所以选择变频器供电电源变压器时，最好选择短路阻抗大的变压器。 安装电抗器 安装电抗器实际上从外部增加变频器供电电源的内阻抗。在变频器的交流侧安装交流电抗器或在变频器的直流侧安装直流电抗器，或同时安装，抑制谐波电流。表一列出了三菱 FR-A540变频器安装电抗器和不安装电抗器的含量对照表。 变压器多相运行 通用变频器的整流部 分是六脉波整流器，所以产生的谐波较大。如果应用变压器的多相运行，使相位角互差 30 如 Y- 、 - 组合的两个变压器构成相当于 12脉波的效果则可减小低次谐波电流 28%，起到了很好的谐波抑制作用。 调节变频器的载波比 只要载波比足够大，较低次谐波就可以被有效地抑制，特别是参考波幅值与载波幅值小于 1时， 13次以下的奇数谐波不再出现。 专用滤波器 该专用滤波器用于检测变频器谐波电流的幅值和相位，并产生一个与谐波电流幅值相同且相位正好相反的电流，通到变频器中，从而可以非常有效地 吸收谐波电流。 3 负载匹配问题及其对策 生产机械的种类繁多，性能和工艺要求各异，其转矩特性是复杂的，大体分为三种类型 :恒转矩负载、风机泵类负载和恒功率负载。针对不同的负载类型，应选择不同类型的变频器。 恒转矩负载 恒转矩负载是指负载转矩与转速无关，任何转速下，转矩均保持恒定。恒转矩负载又分为摩擦类负载和位能式负载。 摩擦类负载的起动转矩一般要求额定转矩的 150%左右，制动转矩一般要求额定转矩的 100%左右，所
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