【正文】 是因為這個原因。目前注塑機的發(fā)展主要集中在： 提高制品尺寸精度和穩(wěn)定性 提高速度、縮短成型周期 生產(chǎn)過程的自動化和省力
但所采用的技術(shù)手段，都離不開以計算機技術(shù)為基礎(chǔ)的自控技術(shù)。注射裝置一般由塑化部件（溶膠筒、螺缸、噴嘴等）、料斗、計量裝置、螺桿傳動裝載及注射油缸和射移油缸等組成。 注塑成型是一個循環(huán)的過程，每一周期主要包括：定量加料——熔融塑化——施壓注射——充模冷卻——啟模取件。 頂杠的頂出與復位頂出電磁閥得電后，頂杠在油壓的推動下將模具內(nèi)的產(chǎn)品頂出。
功能強、弱適當
對于開關(guān)量控制的工程項目，若控制速度要求不高，一般選用抵擋的PLC。一般大型的控制系統(tǒng)都使用模塊式結(jié)構(gòu)，這樣功能易擴展，比整體式靈活。PLC容量的選擇除滿足控制要求外，還應(yīng)留有適當?shù)脑Ａ?，以做備用。根?jù)被控對象的輸入和輸出信號的總點數(shù)，并考慮到今后的調(diào)整和擴充，通常I/O點數(shù)按實際需要的10%～15%考慮備用量。根據(jù)實際需要，PLC相應(yīng)有許多種I/O接口模塊，包括開關(guān)量輸入模塊、開關(guān)量輸出模塊、模擬量輸入及模擬量輸出模塊，可以根據(jù)實際需要進行選擇使用。如果系統(tǒng)的輸出信號變化不是很頻繁，選用繼電器型。
輸出設(shè)備——由PLC的輸出信號驅(qū)動的執(zhí)行元件，如繼電器、接觸器、電磁閥、指示燈等。當射膠時間到達設(shè)定值時，射膠電磁閥斷電自復位，預(yù)塑電磁閥得電，預(yù)塑液壓馬達完成預(yù)塑的同時，螺杠退回原來的位置。如按照該機的中間繼電器的控制線路來編制PLC控制梯 形圖，既繁瑣復雜，又給PLC的程序編制帶來一定的難度，所以對該機PLC控制系統(tǒng)選用SFC（順序功能圖）的程序設(shè)計方法，可以很容易編制程序，達到合理安全的控制目的。 （XX4）上串聯(lián)有常閉的復位開關(guān)X2，當X2為“0”時， 系統(tǒng)不復位，X2為“1”時，注塑機回到初始狀態(tài)（YYYYY6分別為“0”，）。自動啟動開關(guān)X4為“1”，信號轉(zhuǎn)移到S0，順序控制程序完成，返回（RET）主程序，完成一個工作周期。熱電偶是一種感溫元件, 它能將溫度信號轉(zhuǎn)換成熱電勢信號, 通過與電氣測量儀表的配合, 就能測量出被測的溫度。經(jīng)過比較，決定對液壓控制閥的選擇如下： 24EOB6HT型二位四通換向閥3個， AHa10L型單向閥1個，YFL8H1S型溢流閥。它們的主要特點是轉(zhuǎn)速較高、轉(zhuǎn)動慣量小，便于啟動和制動，調(diào)節(jié)(調(diào)速及換向)靈敏度高。 熱繼電器是利用電流的熱效應(yīng)原理工作的保護電器，在電路中作電動機的過載保護。 觸摸屏 觸摸屏作為一種新的電腦輸入設(shè)備，是目前最簡單的、方便、自然的一種人機交互方式，它可以用來監(jiān)控系統(tǒng)的運行情況、發(fā)出相關(guān)命令、顯示設(shè)定比例、實際流量等，這里考慮到與三菱系列PLC的通信，應(yīng)選用三菱F940GOT觸摸屏，它是用RS422連接器與PLC進行通信，完成數(shù)據(jù)的傳送。當線圈斷電時，電磁吸力消失，銜鐵在釋放彈簧的作用下釋放，使觸頭復原：常閉觸頭閉合；常開觸頭斷開。 注塑機正在向高速、高效、節(jié)能方向發(fā)展，一些新的電氣控制設(shè)備以及先進的控制思想在注塑機上的應(yīng)用，將極為有效地幫助注塑機達到這個目的。 eightyfourth project, was the result. Bedford Associates started a new pany dedicated to developing, manufacturing, selling, and servicing this new product: Modicum, which stood for Modular Digital Controllers. One of the people who worked on that project was Dick Morley, who is considered to be the father of the PLC. The Modicum 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 Modicum’s headquarters in North Andover, Massachusetts. It was presented to Modicum by GM, 2when the unit was retired after nearly twenty years of uninterrupted service. Modicum used the 84 moniker at the end of its product range until the 984 made its appearance. The automotive industry is still one of the largest users of PLC. Development Early PLC was designed to replace relay logic systems. These PLC were programmed in ladder logic, which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLC used a form of instruction list programming, based on a stackbased logic solver. Modern PLC can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very highlevel programming language designed to program PLC based on state transition diagrams. Many early PLC did not have acpanying programming terminals that were capable of graphical representation of the logic, and so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra. As programming terminals evolved, it became more mon for ladder logic to be used, for the aforementioned reasons. Newer formats such as State Logic and Function Block (which is similar to the way logic is depicted when using digital integrated logic circuits) exist, but they are still not as popular as ladder logic. A primary reason for this is that PLC solve the logic in a predictable and repeating sequence, and ladder logic allows the programmer (the person writing the logic) to see any issues with the timing of the logic sequence more easily than would be possible in other formats. Programming Early PLC, up to the mid1980s, were programmed using proprietary programming panels or specialpurpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldest PLC used nonvolatile magnetic core memory. More recently, PLC are programmed using application software on personal puters. The puter is connected to the PLC through Ethernet, RS232, RS485 or RS422 cabling. The programming software allows entry and editing of the 3ladderstyle logic. Generally the software provides functions for debugging and troubleshooting the PLC software, for example, by highlighting portions of the logic to show current status during operation or via simulation. The software will upload and download the PLC program, for backup and restoration purposes. In some models of programmable controller, the program is transferred from a personal puter to the PLC though a programming board which writes the program into a removable chip such as an EEPROM or EPROM. The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and munication capabilities of some modern PLC are approximately equivalent to desktop puters. PLClike programming bined with remote I/O hardware, allow a generalpurpose desktop puter to overlap some PLC in certain applications. Regarding the practicality of these desktop puter based logic controllers, it is important to note that they have not been generally accepted in heavy industry because the desktop puters run on less stable operating systems than do PLC, and because the desktop puter hardware is typically not designed to the same levels of tolerance to temperature, humidity, vibration, and longevity as the processors used in PLC. In addition to the hardware limitations of desktop based logic, operating systems such as Windows do not lend themselves to deterministic logic execution, with the result that the logic may not always respond to changes in logic state or input status with the extreme consistency in