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Company Document number：WTUT-WT88Y-W8BBGB-BWYTT-19998
Relays
The Programmable Logic Controller
Early machines were controlled by mechanical means using cams, gears, levers and other basic mechanical devices. As the complexity grew, so
did the need for a more sophisticated control system. This system contained wired relay and switch control elements. These elements were wired as required to provide the control logic necessary for the particular type of machine operation. This was acceptable for a machine that never needed to be changed or modified, but as manufacturing techniques improved and plant changeover to new products became more desirable and necessary, a more versatile means of controlling this equipment had to be developed. Hardwired relay and switch logic was cumbersome and time consuming to modify. Wiring had to be removed and replaced to provide for the new control scheme required. This modification was difficult and time consuming to design and install and any small "bug" in the design could be a major problem to correct since that also required rewiring of the system. A new means to modify control circuitry was needed. The development and testing ground for this new means was the . auto industry. The time period was the late 1960's and early 1970's and the result was the programmable logic controller, or PLC. Automotive plants were confronted with a change in manufacturing techniques every time a model changed and, in some cases, for changes on the same model if improvements had to be made during the model year. The PLC provided an easy way to reprogram the wiring rather than actually rewiring the control system.
The PLC that was developed during this time was not very easy to program. The language was cumbersome to write and required highly trained programmers. These early devices were merely relay replacements and could do very little else. The PLC has at first gradually, and in recent years rapidly developed into a sophisticated and highly versatile control system component. Units today are capable of performing complex math functions including numerical integration and differentiation and operate at the fast microprocessor speeds now available. Older PLCs were capable of only handling discrete inputs and
outputs (that is, on-off type signals), while today's systems can accept and generate analog voltages
and currents as well as a wide range of voltage levels and pulsed signals. PLCs are also designed to be rugged. Unlike their personal computer cousin, they can typically withstand vibration, shock, elevated temperatures, and electrical noise to which manufacturing equipment is exposed.
As more manufacturers become involved in PLC production and development, and PLC capabilities expand, the programming language is also expanding. This is necessary to allow the programming of these advanced capabilities. Also, manufacturers tend to develop their own versions of ladder logic language (the language used to program PLCs). This complicates learning to program PLC's in general since one language cannot be learned that is applicable to all types. However, as with other computer languages, once the basics of PLC operation and programming in ladder logic are learned, adapting to the various manufacturers’ devices is not a complicated process. Most system designers eventually settle on one particular manufacturer that produces a PLC that is personally comfortable to program and has the capabilities suited to his or her area of applications.
It should be noted that in usage, a programmable logic controller is generally referred to as a “PLC” or “programmable controller”. Although the term “programmable controller” is generally accepted, it is not abbreviated “PC” because the abbreviation“PC” is usually used in reference to a personal computer. As we will see in this chapter, a PLC is by no means a personal computer.
Programmable controllers (the shortened name used for programmable logic controllers) are much like personal computers in that the user can be overwhelmed by the vast array of options and configurations available. Also, like personal computers, the best teacher of which one to select is experience. As one gains experience with the various options and configurations available, it becomes less confusing to be able to select the unit that will best perform in a particular application.
The typical system components for a modularized PLC are:
1. Processor.
The processor (sometimes call a CPU), as in the self contained units, is generally specified according to memory required for the program to be In the rmodularizeversions,
capability can also be a factor. This includes features such as highe math functions, PID control loops and optional programming commands. The processor consists of the microprocessor, system memory, serial communication ports for printer, PLC LAN link and external programming device and, in some cases, the system power supply to power the processor and I/O modules.
2. Mounting rack.
This is usually a metal framework with a printed circuit board backplane which provides means for mounting the PLC input/output (I/O) modules and processor. Mounting racks are specified according to the number of modules required to implement the system. The mounting rack provides data and power connections to the processor and modules via the backplane. For CPUs that do not contain a power supply, the rack also holds the modular power supply. There are systems in which the processor is mounted separately and connected by cable to the rack. The mounting rack can be available to mount directly to a panel or can be installed in a standard 19" wide equipment cabinet. Mounting racks are cascadable so several may be interconnected to allow a system to accommodate a large number of I/O modules.
3. Input and output modules.
Input and output (I/O) modules are specified according to the input and output signals associated with the particular application. These modules fall into the categories of discrete, analog, high speed counter or register types.
Discrete I/O modules are generally capable of handling 8 or 16 and, in some cases 32, on-off type inputs or outputs per module. Modules are specified as input or output but generally not both although some manufacturers now offer modules that can be configured with both input and output points in the same unit. The module can be specified as AC only, DC only or AC/DC along with the voltage values for which it is designed.
Analog input and output modules are available and are specified according to the desired resolution and voltage or current range. As with discrete modules, these are generally input or output; however some manufacturers provide analog input and output in
the same module. Analog modules are also available which can directly accept thermocouple inputs for temperature measurement and monitoring by the PLC.
Pulsed inputs to the PLC can be accepted using a high speed countermodule. This module can be capable of measuring the frequency of an inputsignal from a tachometer or other frequency generating device. These modules can also count the incoming pulses if desired. Generally, both frequency and count are available from the same module at the same time if both are required in the application.
Register input and output modules transfer 8 or 16 bit words of information to and from the PLC. These words are generally numbers (BCD or Binary) which are generated from thumbwheel switches or encoder systems for input or data to be output to a display device by the PLC.
Other types of modules may be available depending upon the manufacturer of the PLC and it's capabilities. These include specialized communication modules to allow for the transfer of information from one controller to another. One new development is an I/O Module which allows the serial transfer of information to remote I/O units that can be as far as 12,000 feet away.
4. Power supply.
The power supply specified depends upon the manufacturer's PLC being utilized in the application. As stated above, in some cases a power supply capable of delivering all required power for the system is furnished as part of the processor module. If the power supply is a separate module, it must be capable of delivering a current greater than the sum of all the currents needed by the other modules. For systems with the power supply inside the CPU module, there may be some modules in the system which require excessive power not available from the processor either because of voltage or current requirements that can only be achieved through the addition of a second power source. This is generally true if analog or external communication modules are present since these require ± DC supplies which, in the case of analog modules, must be well regulated.
5. Programming unit.
The programming unit allows the engineer or technician to enter and edit the program to be executed. In it's simplest form it can be a hand held device with a keypad for program entry and a display device (LED or LCD) for viewing program steps or functions, as shown. More advanced systems employ a separate personal computer which allows the programmer to write, view, edit and download the program to the PLC. This is accomplished with proprietary software available from the PLC manufacturer. This software also allows the programmer or engineer to monitor the PLC as it is running the program. With this monitoring system, such things as internal coils, registers, timers and other items not visible externally can be monitored to determine proper operation. Also, internal register data can be altered if required to fine tune program operation. This can be advantageous when debugging the program. Communication with the programmable controller with this system is via a cable connected to a special programming port on the controller. Connection to the personal computer can be through a serial port or from a dedicated card installed in the computer.
A Programmable Controller is a specialized computer. Since it is a computer, it has all the basic component parts that any other computer has; a Central Processing Unit, Memory, Input Interfacing and Output Interfacing.
The Central Processing Unit (CPU) is the control portion of the PLC. It interprets the program commands retrieved from memory and acts on those commands. In present day PLC's this unit is a microprocessor based system. The CPU is housed in the processor module of modularized systems.
Memory in the system is generally of two types; ROM and RAM. The ROM memory contains the program information that allows the CPU to interpret and act on the Ladder Logic program stored in the RAM memory. RAM memory is generally kept alive with an on-board battery so that ladder programming is not lost when the system power is removed. This battery can be a standard dry cell or rechargeable nickel-cadmium type. Newer PLC units are now available with Electrically Erasable Programmable Read Only Memory (EEPROM) which does not require a battery. Memory is also housed in the processor module in modular systems.
Input units can be any of several different types depending on input signals expected as described above. The input section can accept discrete or analog signals of various voltage and current levels. Present day controllers offer discrete signal inputs of both AC and DC voltages from TTL to 250 VDC and from 5 to 250 VAC. Analog input units can accept input levels such as ±10 VDC, ±5 VDC and 4-20 ma. current loop values. Discrete input units present each input to the CPU as a single 1 or 0 while analog input units contain analog to digital conversion circuitry and present the input voltage to the CPU as binary number normalized to the maximum count available from the unit. The number of bits representing the input voltage or current depends upon the resolution of the unit. This number generally contains a defined number of magnitude bits and a sign bit. Register input units present the word input to the CPU as it is received (Binary or BCD).
Output units operate much the same as the input units with the exception that the unit is either sinking (supplying a ground) or sourcing (providing a voltage) discrete voltages or sourcing analog voltage or current. These output signals are presented as directed by the CPU. The output circuit of discrete units can be transistors for TTL and higher DC voltage or Triacs for AC voltage outputs. For higher current applications and situations where a physical contact closure is required, mechanical relay contacts are available. These higher currents, however, are generally limited to about 2-3 amperes. The analog output units have internal circuitry which performs the digital to analog conversion and generates the variable voltage or current output.
The first thing the PLC does when it begins to function is update I/O. This means that all discrete input states are recorded from the input unit and all discrete states to be output are transferred to the output unit. Register data generally has specific addresses associated with it for both input and output data referred to as input and output registers. These registers are available to the input and output modules requiring them and are updated with the discrete data. Since this is input/output updating, it is referred to as I/O Update. The updating of discrete input and output information is accomplished with the use of input and output image registers set aside in the PLC memory. Each discrete input point has associated with it one bit of an input image register. Likewise, each discrete output point
has one bit of an output image register associated with it. When I/O updating occurs, each input point that is ON at that time will cause a 1 to be set at the bit address associated with that particular input. If the input is off, a 0 will be set into the bit address. Memory in today's PLC's is generally configured in 16 bit words. This means that one word of memory can store the states of 16 discrete input points. Therefore, there may be a number of words of memory set aside as the input and output image registers. At I/O update, the status of the input image register is set according to the state of all discrete inputs and the status of the output image register is transferred to the output unit. This transfer of information typically only occurs at I/O update. It may be forced to occur at other times in PLC's which have an Immediate I/O Update command. This command will force the PLC to update the I/O at other times although this would be a special case.
Before a study of PLC programming can begin, it is important to gain a fundamental understanding of the various types of PLCs available, the advantages and disadvantages of each, and the way in which a PLC executes a program. The open frame, shoebox, and modular PLCs are each best suited to specific types of applications based on the environmental conditions, number of inputs and outputs, ease of expansion, and method of entering and monitoring the program. Additionally, programming requires a prior knowledge of the manner in which a PLC receives input information, executes a program, and sends output information. With this information, we are now prepared to begin a study of PLC programming techniques.
When writing programs for PLCs, it is beneficial to have a background in ladder diagramming for machine controls. This is basically the material that was covered in Chapter 1 of this text. The reason for this is that at a fundamental level, ladder logic programs for PLCs are very similar to electrical ladder diagrams. This is no engineers that developed the PLC programming language were sensitive to the fact that most engineers, technicians and electricians who work with electrical machines on a day-to-day basis will be familiar with this method of representing control logic. This would allow someone new to PLCs, but familiar with control diagrams, to be able to adapt very quickly to the
programming language. It is likely that PLC programming language is one of the easiest programming languages to learn.
可编程序控制器
早期的机器用机械的方法采用凸轮控制、齿轮、杠杆和其他基本机械设备。增长的复杂性,因此需要一种更了复杂的控制系统。该系统包含有线继电器和开关控制元素。这些元素,要求提供有线控制逻辑的必要特定类型的机器上运行。这是一台机器,不接受需要变更或修改,但作为制造技术改进和植物转换为新产品变得更加理想的和必要的,一个更加多才多艺该设备具有控制手段,发展。继电器和开关特性的逻辑是笨重,费时要修改。线路必须拆卸和更换提供新的控制方案的要求。这个修改是针对设计、安装、消费的设需要正确接线系统。一个新的方式修改控制电路是需要的。开发和测试基地为这个新的方法美国的汽车工业。晚的时间是1960年代至1970年代初,结果是采用可编程序控制器PLC。面对汽车需要改变生产工艺改变每一次模型,在某些情况下,改善同一模型是在做了模型的一年。PLC提供一个简单的方法来重组接线,而不是实际电路重组的控制系统。
开发了PLC,在这段时间里是不太容易计划的。这PLC语言是难于书写和需要受过高度训练的程序员。这些早期的仅仅是传递装置,可以随心所欲的做很少就可以完成预先的任务。PLC在近年来迅速发展成为一种具有非常高的通用性控制系统的组成部分。今天已经能够执行复杂的运算功能包括数值积分的分化与已开放操作快速处理器的速度。曾经的PLC可只处理离散输入输出(即开关式信号),而今天的系统能够接受并产生模拟的电压和电流以及广泛的电压水平和脉冲信号。PLC设计的目的也是非常明确的。不像个人电脑,它们可以典型地操作振动、冲击、高温、电子噪声、生产设备暴露等。
随着越来越多的厂商卷入了可编程序控制器(PLC)的生产和开发,以及可编程序控制器(PLC)能力的拓展,编程语言也就随之增强了。需要这些先进的编程能力是有必要
的。同时,制造商往往发展自己版本的使用于语言程序(PLC)的梯形逻辑语言。这个复杂可编程逻辑控制器(PLC)在学习编程的时候,既然一个可适用于所有的类型语言不能完全做到了解。然而,就像其他的计算机语言一样,可编程序控制器(PLC)的基本操作和编程逻辑是有学习阶段，去适应不同厂家的设备，这不是一个复杂的过程。大多数的系统设计师最终在一个特定的制造厂商自己产生一个可编程序控制器(PLC)的程序并具备适合它的地区性的应用能力。
应该指出的是,使用一个可编程逻辑控制器,普遍被称为“PLC”或“可编程控制器”。虽然术语“可编程控制器”已被普遍接受,但它并不是缩写“PC”，因为简称的“PC”通常用于个人电脑。正如我们所看到的, PLC控制绝不是一台个人电脑。
可编程控制器(缩短名字用于可编程逻辑控制器)像个人电脑用户可以做出了巨量的选择和配置。来到使用者面前,就像个人电脑，是最好老师的一个很好的选择。考虑到不同的收益和配置的选择,它就可以选择单位，使其变得能够将最好地履行在一个特定的应用。
典型的系统部件模块化可编程序控制器(PLC)是:
1、处理器
处理器(有时叫一个CPU),就像在独立控制单元,通常是根据指定的内存需求为程序是什么实施。在模块化的版本,能力也可以是一个重要的因素。这包括高等数学功能等特点,采用PID控制回路可编程的命令。处理器构成的微处理器、系统内存,串行通讯港口打印机,可编程序控制器(PLC)局域网连接装置和外部编程,在某些情况下,该系统供电电源处理器和I / O模块。
2、安装架
这通常是金属框架,印刷电路板提供用于安装底板意味着PLC输入/输出(I / O)模块和处理器。指定安装架是根据模块的数量必须执行系统。安装架提供数据和电力连接处理器与模块通过底板。对于cpu,它不包含一个电源、架子上也成立这种模块化的电力供应。有系统处理器安装连接电缆单独架子上。安装架能可直接向山面板或者可以安装在标准19“宽设备内阁。cascadable安装架是这么多允许一个系统互连来容纳大量I / O模块。
3。输入和输出模块
输入和输出(I / O)模块根据输入指定输出信号与之关联的特定应用程序。这些模块秋天分成离散、模拟、高速计数器或注册类型。
离散I / O模块一般都是有能力处理8和16,在某些情况下,开关类型的输入和输出一个模块。模块指定为输入或输出,但一般虽然一些制造商们提供了模块可配置和输入输出点在同一单元内。
模拟输入和输出模块都是可行的,适用于在合同中规定的预期的分辨率和电压或电流范围。随着这些都是一般离散输入或输出模块,一些制造商就在相同的模块提供模拟的输入和输出。PLC模拟模块也可以输入可直接接受热电偶的温度测量和监测。
脉冲输入与可编程序控制器(PLC)可以接受使用高速计数器模块。这一个模块能够从一个转速或其他频率产生装置测量频率的一个输入信号。这些模块也可以计算想要的脉冲计数。一般来说, 如果双方都需要应用程序，在同一时间内，两个频率和计数可从相同的模块执行。
输入和输出模块寄存器从PLC传递8和16位字信息。这些就是一般编号(BCD码或二进制), 由PLC产生复开关或编码器系统的数据输入或输出显示于设备。提供的其他类型的模块也可以根据可编程序控制器(PLC)的制造商的能力而定。这些包括专
业通信模块,以允许转让信息从一个控制器到另一个地方。一个新的发展是一个I/O
模块允许串行传输远程I/O信息,可以到12000英尺远的地方。
4、电力供应
电源指定取决于厂商的可编程序控制器(PLC)中所使用的应用程序。如前所述,在某些情况下一分力量供应能力提供所需的电力系统布置处理模块的一部分。如果电源是一个独立的模块,它提供的电流必须能大于所需的其它模块的总和电流。系统是在CPU模块供电, 因为电压或电流的要求有一些模块的实现不可以从处理器获得过多的能量,只能通过增加第二电源，一般来说这是事实。如果模拟外部通信模块,目前由于这些要求在直流供应的情况下,在模拟模块必须进行调整。
5、编程单元
编程单位允许工程师或技术员编辑要执行的程序。编程的最简单的形式可以是一种手握设备键盘程序输入和显示设备(LED或LCD)来观看程序步骤或功能。更多的先进的系统是使用一个单独的个人电脑, 可编程序控制器(PLC)允许程序员写、查看、编辑和下载程序，这是制造商提供了从可编程序控制器(PLC) 的专有软件。该软件还可以让程序或工程师监控PLC来运行这个程序。这个监测系统,诸如可以被监控的内部线圈、寄存器、定时器和其看不见的外部来确定适当的操作。同时如果需要微调的程序操作, 可以改变内部注册数据，有利的程序可以调试。该系统可编程控制器的沟通是通过电缆连接到一个专门的编程接口控制器。这台计算机可以通过串行口或安装在一个专门的卡片连接到个人计算机。
一个可编程控制器是一个专门的计算机。因为它是一台电脑所有的基本组成部分,任何其他计算机都具有中央处理器、存储器和输入和输出接口。
中央处理器(CPU)是可编程序控制器(PLC)控制的重要部分。它可以直接从记忆和行为对那些命令解释相同的程序的命令。在当前的可编程序控制器(PLC)的这个单位是一个以微处理器为基础的系统。中央处理器(CPU)在系统模块的处理器模块。
记忆系统通常是两种类型的,只读存储器和随机存储器。ROM的记忆包含程序信息，允许中央处理器解释和行为的梯形逻辑程序存储在RAM记忆。RAM记忆通常为了不失去梯形编程系统功率的移除。这种电池可以是一个标准的干电池充电nickel-cadmium或类型。现在可更新的可编程序控制器(PLC)单位与电可擦可编程只读存储器(EEPROM)不需要电池。记忆也在模块化系统的处理器模块。
任何不同的类型的输入单位可以取决于预期的输入信号。输入一段可以接受离散的模拟信号。今天的控制器提供两种离散信号的输入交流和直流电压TTL 250 VDC,从5到250 VAC。模拟输入单位可以接受输入水平线,比如±10伏直流电、±5伏直流电和4电流环值。每CPU作为一个单一的1或0在模拟输入单元的内容模拟/数字转换电路和现在的输入电压到中央处理器，离散输入单元输入到现在以二进制规格化以最大字数数目进行传输。位的数字取决于该决议的单位，代表输入电压或电流。通常有一个定义数量的大小和数量位符号位。现在登记这个词输入单元输入到中央处理器,因为它是得到了二进制或BCD码)。
操作相同的输出单元和输入单元的除外，要么单位提供一个地或采购(提供一个电压)离散电压或采购模拟电压或电流。在输出信号的引导下,提出了中央处理器。不连续的输出电流可以为TTL和较高的直流电压或Triacs AC电压输出。为更大的电流的应用在关闭时使中间继电器接点可用。这些更大的电流一般限于2到3安培。电路输出的数字模拟的模拟模块转换生成可变电压或电流输出。
第一次使用可编程序控制器(PLC)时,它就开始了更新I/O的功能。这意味着所有离散输入状态记录从输入单元把所有离散的状态输出转移到输出单元。注册数据一般都有特定的地址和与之相关的输入输出数据，都称为输入和输出寄存器。这些调试寄存器是输入、输出模块,要求他们与离散数据一同更新。由于这是输入/输出更新,它被称为I/O更新。更新离散输入和输出信息是完成使用图像的输入和输出寄存器来搁置PLC的记忆。每一个离散输入登记相关的输入图。也就是说,每个离散输出点有一个小的输出图像登记与它联合起来。当I/O更新发生,每一个输入点,就是在那时会导致的第一个被设定的地址伴随着那个特定的输入。如果输入是关闭的,将会把一个0送到地址。今天的PLC内存中配置的通常是16位字。这意味着一个词可储存记忆的状态离散输入16。因此,有可能数量的内存留出的是图像输入与输出寄存器。I/O更新的情况是按设定输入图像登记的离散状态，从输入和输出的图像状态寄存器转移到输出单元。通常只有传输信息发生时在I/O更新。它可能被迫发生在其他可编程序控制器(PLC)的时代有很明显的I/O更新的命令。这个命令在其他时候将迫使PLC更新I/O,尽管这是一个特殊例子。
在研究的开始,PLC编程可以是很重要的一个模块。获得了解各种类型的plc,以及可编程序控制器(PLC)怎样执行一个程序。开放的框架和模块化的plc都适合在特定类型的基础上的应用环境条件,数量的输入和输出的扩张和进入监控程序。此外,编程需要优先接收输入信息、执行PLC程序,并输出信息。根据这些信息,我们开始研究PLC程序设计。
当写程序时,梯形图控制机器。其原因是,在一个基本的标准的逻辑plc程序是非常相似的电气图，这不是巧合。工程师们对发展PLC编程语言很敏感，大多数工程师、技术员和电工电气机械工作人员每天将熟悉这种方法的控制逻辑,代表这将允许
更新,只有熟悉plc控制图,能够适应非常迅速的编程语言。PLC编程语言是一个最简单的编程语言学习。
快速外文文献翻译 在科研过程中阅读翻译外文文献是一个非常重要的环节，许多领域高水平的文献都是外文文献，借鉴一些外文文献翻译的经验是非常必要的。由于特殊原因我翻译外文文献的机会比较多，慢慢地就发现了外文文献翻译过程中的三大利器：Google“翻译”频道、金山词霸（完整版本）和CNKI“翻译助手"。 具体操作过程如下： 1.先打开金山词霸自动取词功能，然后阅读文献； 2.遇到无法理解的长句时，可以交给Google处理，处理后的结果猛一看，不堪入目，可是经过大脑的再处理后句子的意思基本就明了了； 3.如果通过Google仍然无法理解，感觉就是不同，那肯定是对其中某个“常用单词”理解有误，因为某些单词看似很简单，但是在文献中有特殊的意思，这时就可以通过CNKI的“翻译助手”来查询相关单词的意思，由于CNKI的单词意思都是来源与大量的文献，所以它的吻合率很高。 另外，在翻译过程中最好以“段落”或者“长句”作为翻译的基本单位，这样才不会造成“只见树木，不见森林”的误导。 注： 1、Google翻译：https://www.doczj.com/doc/df5625411.html,/language_tools google，众所周知，谷歌里面的英文文献和资料还算是比较详实的。我利用它是这样的。一方面可以用它查询英文论文，当然这方面的帖子很多，大家可以搜索，在此不赘述。回到我自己说的翻译上来。下面给大家举个例子来说明如何用吧比如说“电磁感应透明效应”这个词汇你不知道他怎么翻译， 首先你可以在CNKI里查中文的，根据它们的关键词中英文对照来做，一般比较准确。 在此主要是说在google里怎么知道这个翻译意思。大家应该都有词典吧，按中国人的办法，把一个一个词分着查出来，敲到google里，你的这种翻译一般不太准，当然你需要验证是否准确了，这下看着吧，把你的那支离破碎的翻译在google里搜索，你能看到许多相关的文献或资料，大家都不是笨蛋，看看，也就能找到最精确的翻译了，纯西式的！我就是这么用的。 2、CNKI翻译：https://www.doczj.com/doc/df5625411.html, CNKI翻译助手，这个网站不需要介绍太多，可能有些人也知道的。主要说说它的有点，你进去看看就能发现：搜索的肯定是专业词汇，而且它翻译结果下面有文章与之对应（因为它是CNKI检索提供的，它的翻译是从文献里抽出来的），很实用的一个网站。估计别的写文章的人不是傻子吧，它们的东西我们可以直接拿来用，当然省事了。网址告诉大家，有兴趣的进去看看，你们就会发现其乐无穷！还是很值得用的。https://www.doczj.com/doc/df5625411.html, 3、网路版金山词霸（不到1M）：https://www.doczj.com/doc/df5625411.html,/6946901637944806 翻译时的速度： 这里我谈的是电子版和打印版的翻译速度，按个人翻译速度看，打印版的快些，因为看电子版本一是费眼睛，二是如果我们用电脑，可能还经常时不时玩点游戏，或者整点别的，导致最终SPPEED变慢，再之电脑上一些词典（金山词霸等）在专业翻译方面也不是特别好，所以翻译效果不佳。在此本人建议大家购买清华大
Programmable logic controller A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result. 1.History The PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire each and every relay. In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner. One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84
前言 在目前激烈的市场竞争中，产品投入市场的迟早往往是成败的关键。模具是高质量、高效率的产品生产工具，模具开发周期占整个产品开发周期的主要部分。因此客户对模具开发周期要求越来越短，不少客户把模具的交货期放在第一位置，然后才是质量和价格。因此，如何在保证质量、控制成本的前提下加工模具是值得认真考虑的问题。模具加工工艺是一项先进的制造工艺，已成为重要发展方向，在航空航天、汽车、机械等各行业得到越来越广泛的应用。模具加工技术，可以提高制造业的综合效益和竞争力。研究和建立模具工艺数据库，为生产企业提供迫切需要的高速切削加工数据，对推广高速切削加工技术具有非常重要的意义。本文的主要目标就是构建一个冲压模具工艺过程，将模具制造企业在实际生产中结合刀具、工件、机床与企业自身的实际情况积累得高速切削加工实例、工艺参数和经验等数据有选择地存储到高速切削数据库中，不但可以节省大量的人力、物力、财力，而且可以指导高速加工生产实践，达到提高加工效率，降低刀具费用，获得更高的经济效益。 1.冲压的概念、特点及应用 冲压是利用安装在冲压设备（主要是压力机）上的模具对材料施加压力，使其产生分离或塑性变形，从而获得所需零件（俗称冲压或冲压件）的一种压力加工方法。冲压通常是在常温下对材料进行冷变形加工，且主要采用板料来加工成所需零件，所以也叫冷冲压或板料冲压。冲压是材料压力加工或塑性加工的主要方法之一，隶属于材料成型工程术。 冲压所使用的模具称为冲压模具，简称冲模。冲模是将材料（金属或非金属）批量加工成所需冲件的专用工具。冲模在冲压中至关重要，没有符合要求的冲模，批量冲压生产就难以进行；没有先进的冲模，先进的冲压工艺就无法实现。冲压工艺与模具、冲压设备和冲压材料构成冲压加工的三要素，只有它们相互结合才能得出冲压件。 与机械加工及塑性加工的其它方法相比，冲压加工无论在技术方面还是经济方面都具有许多独特的优点，主要表现如下； (1) 冲压加工的生产效率高，且操作方便，易于实现机械化与自动化。这是
中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。
Injection Molding The basic concept of injection molding revolves around the ability of a thermoplastic material to be softened by heat and to harden when cooled .In most operations ,granular material (the plastic resin) is fed into one end of the cylinder (usually through a feeding device known as a hopper ),heated, and softened(plasticized or plasticized),forced out the other end of the cylinder, while it is still in the form of a melt, through a nozzle into a relatively cool mold held closed under pressure.Here,the melt cools and hardens until fully set-up. The mold is then opened, the piece ejected, and the sequence repeated. Thus, the significant elements of an injection molding machine become: 1) the way in which the melt is plasticized (softened) and forced into the mold (called the injection unit); 2) the system for opening the mold and closing it under pressure (called the clamping unit);3) the type of mold used;4) the machine controls. The part of an injection-molding machine, which converts a plastic material from a sold phase to homogeneous seni-liguid phase by raising its temperature .This unit maintains the material at a present temperature and force it through the injection unit nozzle into a mold .The plunger is a combination of the injection and plasticizing device in which a heating chamber is mounted between the plunger and mold. This chamber heats the plastic material by conduction .The plunger, on each stroke; pushes unbelted plastic material into the chamber, which in turn forces plastic melt at the front of the chamber out through the nozzle The part of an injection molding machine in which the mold is mounted, and which provides the motion and force to open and close the mold and to hold the mold close with force during injection .This unit can also provide other features necessary for the effective functioning of the molding operation .Moving
五分钟搞定5000字－外文文献翻译 在科研过程中阅读翻译外文文献是一个非常重要的环节，许多领域高水平的文献都是外文文献，借鉴一些外文文献翻译的经验是非常必要的。由于特殊原因我翻译外文文献的机会比较多，慢慢地就发现了外文文献翻译过程中的三大利器：Google“翻译”频道、金山词霸（完整版本）和CNKI“翻译助手"。 具体操作过程如下： 1.先打开金山词霸自动取词功能，然后阅读文献； 2.遇到无法理解的长句时，可以交给Google处理，处理后的结果猛一看，不堪入目，可是经过大脑的再处理后句子的意思基本就明了了； 3.如果通过Google仍然无法理解，感觉就是不同，那肯定是对其中某个“常用单词”理解有误，因为某些单词看似很简单，但是在文献中有特殊的意思，这时就可以通过CNKI的“翻译助手”来查询相关单词的意思，由于CNKI的单词意思都是来源与大量的文献，所以它的吻合率很高。 另外，在翻译过程中最好以“段落”或者“长句”作为翻译的基本单位，这样才不会造成“只见树木，不见森林”的误导。 注： 1、Google翻译：https://www.doczj.com/doc/df5625411.html,/language_tools google，众所周知，谷歌里面的英文文献和资料还算是比较详实的。我利用它是这样的。一方面可以用它查询英文论文，当然这方面的帖子很多，大家可以搜索，在此不赘述。回到我自己说的翻译上来。下面给大家举个例子来说明如何用吧 比如说“电磁感应透明效应”这个词汇你不知道他怎么翻译， 首先你可以在CNKI里查中文的，根据它们的关键词中英文对照来做，一般比较准确。
在此主要是说在google里怎么知道这个翻译意思。大家应该都有词典吧，按中国人的办法，把一个一个词分着查出来，敲到google里，你的这种翻译一般不太准，当然你需要验证是否准确了，这下看着吧，把你的那支离破碎的翻译在google里搜索，你能看到许多相关的文献或资料，大家都不是笨蛋，看看，也就能找到最精确的翻译了，纯西式的！我就是这么用的。 2、CNKI翻译：https://www.doczj.com/doc/df5625411.html, CNKI翻译助手，这个网站不需要介绍太多，可能有些人也知道的。主要说说它的有点，你进去看看就能发现：搜索的肯定是专业词汇，而且它翻译结果下面有文章与之对应（因为它是CNKI检索提供的，它的翻译是从文献里抽出来的），很实用的一个网站。估计别的写文章的人不是傻子吧，它们的东西我们可以直接拿来用，当然省事了。网址告诉大家，有兴趣的进去看看，你们就会发现其乐无穷！还是很值得用的。https://www.doczj.com/doc/df5625411.html, 3、网路版金山词霸（不到1M）：https://www.doczj.com/doc/df5625411.html,/6946901637944806 翻译时的速度： 这里我谈的是电子版和打印版的翻译速度，按个人翻译速度看，打印版的快些，因为看电子版本一是费眼睛，二是如果我们用电脑，可能还经常时不时玩点游戏，或者整点别的，导致最终SPPEED变慢，再之电脑上一些词典（金山词霸等）在专业翻译方面也不是特别好，所以翻译效果不佳。在此本人建议大家购买清华大学编写的好像是国防工业出版社的那本《英汉科学技术词典》，基本上挺好用。再加上网站如：google CNKI翻译助手，这样我们的翻译速度会提高不少。 具体翻译时的一些技巧（主要是写论文和看论文方面） 大家大概都应预先清楚明白自己专业方向的国内牛人，在这里我强烈建议大家仔
Application of PLC PLC is one kind specially for the digital operation operation electronic installation which applies under the industry environment designs. It uses may the coding memory, uses for in its internal memory operation and so on actuating logic operation, sequence operation, time, counting and arithmetic operation instructions, and can through digital or the simulation-like input and the output, controls each type the machinery or the production process. PLC and the related auxiliary equipment should according to form a whole easy with the industrial control system, easy to expand its function the principle to design.” In the 1970s the last stage, the programmable controller entered the practical application development phase, the computer technology has introduced in comprehensively the programmable controller, causes its function to have the leap. The higher operating speed, the subminiature volume, the more reliable industry antijamming design, the simulation quantity operation, the PID function and the extremely high performance-to-price ratio has established it in the modern industry status. In the early-1980s, the programmable controller has obtained the widespread application in the advanced industrial nation. This time programmable controller develops the characteristic is large-scale, the high velocity, the high performance, the product seriation. This stage's another characteristic is in the world produces the programmable controller's country to increase day by day, the output rises day by day. This symbolizes that the programmable controller marched into the mature stage. The 20th century last stage, the programmable controller's development characteristic was even more adapts in the modern industry need. From the control scale, this time has developed the large-scale machinery and subminiature machine; From the control, was born various special function unit, used in the pressure, the temperature, the rotational speed, the displacement and so on all kinds of control situation; From product necessary ability, has produced each kind of man-machine contact surface unit, the correspondence unit, caused to apply the programmable controller's industrial control equipment necessary to be easier. At present, the programmable controller in domain and so on machine manufacture, petroleum chemical industry, metallurgy steel and iron, automobile, light industry applications obtained the considerable development.
(此文档为word格式，下载后您可任意编辑修改！) 冷冲模具使用寿命的影响及对策 冲压模具概述 冲压模具--在冷冲压加工中，将材料(金属或非金属)加工成零件(或半成品)的一种特殊工艺装备，称为冷冲压模具(俗称冷冲模)。冲压--是在室温下，利用安装在压力机上的模具对材料施加压力，使其产生分离或塑性变形，从而获得所需零件的一种压力加工方法。 冲压模具的形式很多，一般可按以下几个主要特征分类： 1?根据工艺性质分类 (1)冲裁模沿封闭或敞开的轮廓线使材料产生分离的模具。如落料模、冲孔模、切断模、切口模、切边模、剖切模等。 (2)弯曲模使板料毛坯或其他坯料沿着直线(弯曲线)产生弯曲变形，从而获得一定角度和形状的工件的模具。 (3)拉深模是把板料毛坯制成开口空心件，或使空心件进一步改变形状和尺寸的模具。 (4)成形模是将毛坯或半成品工件按图凸、凹模的形状直接复制成形，而材料本身仅产生局部塑性变形的模具。如胀形模、缩口模、扩口模、起伏成形模、翻边模、整形模等。2?根据工序组合程度分类 (1)单工序模在压力机的一次行程中，只完成一道冲压工序的模具。 (2)复合模只有一个工位，在压力机的一次行程中，在同一工位上同时完成两道或两道以上冲压工序的模具。 (3)级进模(也称连续模) 在毛坯的送进方向上，具有两个或更多的工位，在压力机的一次行程中，在不同的工位上逐次完成两道或两道以上冲压工序的模具。 冲冷冲模全称为冷冲压模具。 冷冲压模具是一种应用于模具行业冷冲压模具及其配件所需高性能结构陶瓷材料的制备方法，高性能陶瓷模具及其配件材料由氧化锆、氧化钇粉中加铝、错元素构成，制备工艺是将氧化锆溶液、氧化钇溶液、氧化错溶液、氧化铝溶液按一定比例混合配成母液，滴入碳酸氢铵，采用共沉淀方法合成模具及其配件陶瓷材料所需的原材料，反应生成的沉淀经滤水、干燥，煅烧得到高性能陶瓷模具及其配件材料超微粉，再经过成型、烧结、精加工，便得到高性能陶瓷模具及其配件材料。本发明的优点是本发明制成的冷冲压模具及其配件使用寿命长，在冲压过程中未出现模具及其配件与冲压件产生粘结现象，冲压件表面光滑、无毛刺，完全可以替代传统高速钢、钨钢材料。 冷冲模具主要零件冷冲模具是冲压加工的主要工艺装备，冲压制件就是靠上、下模具的相对运动来完成的。 加工时由于上、下模具之间不断地分合，如果操作工人的手指不断进入或停留在模具闭合区，便会对其人身安全带来严重威胁。 1
1 Bit Logic Instructions 1.1 Overview of Bit Logic Instructions 1.1.1 Description Bit logic instructions work with two digits, 1 and 0. These two digits form the base of a number system called the binary system. The two digits 1 and 0 are called binary digits or bits. In the world of contacts and coils, a 1 indicates activated or energized, and a 0 indicates not activated or not energized. The bit logic instructions interpret signal states of 1 and 0 and combine them according to Boolean logic. These combinations produce a result of 1 or 0 that is called the “result of logic operation” (RLO). The logic operations that are triggered by the bit logic instructions perform a variety of functions. There are bit logic instructions to perform the following functions: ---| |--- Normally Open Contact (Address) ---| / |--- Normally Closed Contact (Address) ---(SAVE) Save RLO into BR Memory XOR Bit Exclusive OR ---( ) Output Coil ---( # )--- Midline Output ---|NOT|--- Invert Power Flow The following instructions react to an RLO of 1: ---( S ) Set Coil ---( R ) Reset Coil SR Set-Reset Flip Flop RS Reset-Set Flip Flop Other instructions react to a positive or negative edge transition to perform the following functions: ---(N)--- Negative RLO Edge Detection ---(P)--- Positive RLO Edge Detection NEG Address Negative Edge Detection POS Address Positive Edge Detection
模具工业是国民经济的基础工业，是国际上公认的关键工业，工业发达国家称之为“工业之母”。模具成型具有效率高，质量好，节省原材料，降低产品成本等优点。采用模具制造产品零件已成为当今工业的重要工艺手段。模具在机械，电子，轻工，纺织，航空，航天等工业领域里，已成为使用最广泛的工业化生产的主要工艺装备，它承担了这些工业领域中60%--80%产品零件，组件和部件的加工生产。“模具就是产品质量”，“模具就是经济效益”的观念已被越来越多的人所认识和接受。在中国，人们已经认识到模具在制造业中的重要基础地位，认识更新换代的速度，新产品的开发能力，进而决定企业的应变能力和市场竞争能力。在目前用薄钢板制造发动机罩盖的传统还是会持续相当一段时间，所以有必要在钢板的基础上通过利用计算机软件的功能分析零件的工艺性能（结构合理，受力，是否容易冲出破面、、、），发现现有零件的不足之处，讨论并确定改进这些不足之处，进而改善模具的设计，改良冲裁方式；最终实现产品的改良，改善产品的力学性能，外观，使用效果，和造价等等。冲压加工是通过模具来实现的，从模具角度来看，模具生产技术水平的高低，已成为衡量一个国家产品制造水平高低的重要标志，因为模具在很大程度上决定着产品的质量、效益和新产品的开发能力。“模具是工业生产的基础工艺装备”也已经取得了共识。据统计，在电子、汽车、电机、电器、仪器、仪表、家电和通信等产品中，60%～80%的零部件都要依靠模具成形。用模具生产制件所具备的高精度、高复杂程度、高一致性、高生产率和低消耗，是其他加工制造方法所不能比拟的。同时，冲压加工也创造了巨大的价值增值，模具是“效益放大器”，用模具生产的最终产品的价值，往往是模具自身价值的几十倍、上百倍。目前全世界模具年产值约为600亿美元，日、美等工业发达国家的模具工业产值已超过机床工业，从1997年开始，我国模具工业产值也超过了机床工业产值。其中冲压模具在所有模具（锻造模、压铸模、注塑模等）中，无论从数量、重量或者是从价值上都位居榜首。 由此可见，板料冲压加工及其模具制造技术对国民经济的发展已经并将继续作出重大的贡献。随着我国经济的发展，对这种生产技术的发展及专业技术人才的需求将与日俱增。因此，加强对板料冲压加工及其模具制造技术的研究，具有重要的意义。 现状和发展趋势：经过了100多年的发展,目前小型汽车发动机的罩壳的设计技术已经相当成熟的了，但是随着各式各样的小型发动机的开发，发动机的前后罩也做了很大的改进。现在，对小型汽车发动机的罩壳的改进主要表现在对其构造材料的改进；例如用树脂基复合材料替代传统的薄钢板，用 RTM制造发动机水箱、隔热罩、发动机罩等等，由于用复合材料来取代原有金属的发动机壳体类零件，重量会有所减轻，且成本也将大大降低，对制造商而言，这个改进创造了很大了利润空间，所以这方面的技术进步还会持续相当长一段时间。就目前而言，我国冲压模具还存在许多问题，其中模具生产周期、质量和数量仍旧是关键。与国际水平相比，一般来说，我国冲压模具生产周期要比国外先进水平长、寿命约
Analysis on the Chinese Enterprise Financing Abstract:The main sources of financing for small and medium sized enterprises (SMEs) are equity, trade credit paid on time, long and short term bank credits, delayed payment on trade credit a nd other debt. The marginal costs of each financing instrument are driven by asymmetric informatio n and transactions costs associated with nonpayment. According to the Pecking Order Theory, firms will choose the cheapest source in terms of cost. In the case of the static trade-off theory, firms cho ose finance so that the marginal costs across financing sources are all equal, thus an additional Euro of financing is obtained from all the sources whereas under the Pecking Order Theory the source is determined by how far down the Pecking Order the firm is presently located. In this paper, we argue that both of these theories miss the point that the marginal costs are dependent of the use of the fun ds, and the asset side of the balance sheet primarily determines the financing source for an additiona l Euro. An empirical analysis on a unique dataset of Portuguese SMEs confirms that the compositio n of the asset side of the balance sheet has an impact of the type of financing used and the Pecking Order Theory and the traditional Static Trade-off theory are rejected. For SME the main sources of financing are equity (internally generated cash), trade credit, ban k credit and other debt. The choice of financing is driven by the costs of the sources which is primar ily determined by costs of solving the asymmetric information problem and the expected costs assoc iated with non-payment of debt. Asymmetric information costs arise from collecting and analysing i nformation to support the decision of extending credit, and the non-payment costs are from collectin g the collateral and selling it to recover the debt. Since SMEs’ management and shareholders are oft en the same person, equity and internally generated funds have no asymmetric information costs an d equity is therefor e the cheapest source. 1 Asset side theory of SME financing In the previous section we have suggested that SME’s in Portugal are financed using internal g enerated cash, cheap trade credits, long and short-term bank loans and expensive trade credits and o ther loans. In this section the motives behind the different types of financing are discussed. 1.1 Cheap Trade credits The first external financing source we will discuss is trade-credits. Trade credits are interesting
毕业设计论文外文翻译
模具的发展 1模具在工业生产中的地位 模具是大批量生产同形产品的工具，是工业生产的主要工艺装备。 采用模具生产零部件，具有生产效率高、质量好、成本低、节约能源和原材料等一系列优点，用模具生产制件所具备的高精度、高复杂程度、高一致性、高生产率和低消耗，是其他加工制造方法所不能比拟的。已成为当代工业生产的重要手段和工艺发展方向。现代经济的基础工业。现代工业品的发展和技术水平的提高，很大程度上取决于模具工业的发展水平，因此模具工业对国民经济和社会发展将起越来越大的作用。1989年3月国务院颁布的《关于当前产业政策要点的决定》中，把模具列为机械工业技术改造序列的第一位、生产和基本建设序列的第二位(仅次于大型发电设备及相应的输变电设备)，确立模具工业在国民经济中的重要地位。1997年以来，又相继把模具及其加工技术和设备列入了《当前国家重点鼓励发展的产业、产品和技术目录》和《鼓励外商投资产业目录》。经国务院批准，从1997年到2000年，对80多家国有专业模具厂实行增值税返还70%的优惠政策，以扶植模具工业的发展。所有这些，都充分体现了国务院和国家有关部门对发展模具工业的重视和支持。目前全世界模具年产值约为600亿美元，日、美等工业发达国家的模具工业产值已超过机床工业，从1997年开始，我国模具工业产值也超过了机床工业产值。 据统计，在家电、玩具等轻工行业，近90％的零件是综筷具生产的；在飞机、汽车、农机和无线电行业，这个比例也超过60％。例如飞机制造业，某型战斗机模具使用量超过三万套，其中主机八千套、发动机二千套、辅机二万套。从产值看，80年代以来，美、日等工业发达国家模具行业的产值已超过机床行业，并又有继续增长的趋势。据国际生产技术协会预测，到2000年，产品尽件粗加工的75%、精加工的50％将由模具完成；金属、塑料、陶瓷、橡胶、建材等工业制品大部分将由模具完成，50％以上的金属板材、80％以上的塑料都特通过模具转化成制品。