八路搶答器的PLC控制設(shè)計(jì)

1、八路搶答器的PLC控制摘 要搶答器的定義，即在競(jìng)賽、文體娛樂活動(dòng)（搶答活動(dòng)）中，能準(zhǔn)確、公正、直觀地判斷出搶答者的機(jī)器。在現(xiàn)今社會(huì)里，搶答器在娛樂節(jié)目、拍賣會(huì)等場(chǎng)合越來越得到重用，它可以幫助改善工作方式，方便思想的快速交流，使工作效率得到較大的提升。只要按一下按鈕就能輕松的表達(dá)自己的想法，簡單快捷。充分利用科學(xué)技術(shù)為生活服務(wù)，是現(xiàn)代社會(huì)發(fā)展的方向。實(shí)現(xiàn)搶答器功能的方式由多種，可以采用早期的模擬電路、數(shù)字電路或模數(shù)混合電路。近年來隨著科技的飛速發(fā)展。單片機(jī)、PLC的應(yīng)用不斷地走向深入。同時(shí)帶動(dòng)傳統(tǒng)的控制檢測(cè)技術(shù)的不斷更新。現(xiàn)介紹的就是一種利用日本三菱公司生產(chǎn)的型PLC作為核心控制器的八路搶答器系

2、統(tǒng)。給出了系統(tǒng)結(jié)構(gòu)圖、梯形圖以及輸入輸出端子的分配方案。關(guān)鍵詞：PLC ，搶答器，梯形圖，設(shè)計(jì) ！所有下載了本文的注意：本論文附有CAD圖紙和完整版最終設(shè)計(jì)，凡下載了本文的讀者請(qǐng)留下你的聯(lián)系方式（QQ郵箱），或加我百度用戶名QQ，我把圖紙發(fā)給你。最后，希望此文能夠幫到你！ANSWER EIGHT-WAY PLC DEVICE CONTROLABSTRACTAnswers definition, that is, in the contest, style entertainment (Answer activities) in an accurate, fair and visually de

3、termine the machine Answer. In todays society, Answer in entertainment, the auction will be increasingly important and so on, it can help to improve the working methods to facilitate the rapid exchange of ideas, so that a greater work efficiency improved. Just click the button will be able to easily

4、 express their ideas, simple and quick. Make full use of science and technology services for the life of modern social development.Answer feature to achieve a combination of methods can be used early analog circuits, digital circuits or analog-to-digital hybrid circuits. In recent years, with the ra

5、pid development of science and technology. Single-chip, PLC applications to continue to depth. At the same time, the control of traditional detection technologies constantly updated. Are introduced is a production of Japans Mitsubishi FX2N-64MR-based PLC as the core of the eight-way controller syste

6、m Answer. The system structure diagram, ladder diagram, as well as the distribution of input and output terminal program. KEY WORDS: PLC，Answer devices，Ladder Diagram，Design目錄前言1第1章 PLC的概述21.1 PLC定義21.2 PLC發(fā)展趨勢(shì)21.3 PLC基本結(jié)構(gòu)及原理3第2章 硬件電路設(shè)計(jì)62.1 搶答器的控制要求62.2 控制特點(diǎn)分析62.3 FX2N系列PLC硬件認(rèn)識(shí)62.4 I/O口的分配及硬件接線圖8第3章

7、 軟件程序設(shè)計(jì)113.1 梯形圖設(shè)計(jì)113.2 工作過程分析11結(jié) 論19謝 辭20參考文獻(xiàn)21外文資料翻譯22前言我想對(duì)于搶答器，大家都不會(huì)陌生吧，在我們的日常生活中處處可見，和我們的生活其實(shí)已經(jīng)是密不可分了。如果我們仔細(xì)觀察的話便會(huì)發(fā)現(xiàn)，無論是在學(xué)校、工廠、軍隊(duì)還是電視節(jié)目中, 都可能會(huì)舉辦各種各樣的搶答競(jìng)賽, 甚至是選舉投票，這些都關(guān)系到我們的切身利益，譬如學(xué)校要舉辦一場(chǎng)歷史知識(shí)的競(jìng)賽，要求每個(gè)班挑選出若干個(gè)選手一起進(jìn)行比賽，勝者可以得到豐厚的獎(jiǎng)勵(lì)，校方要求參賽選手個(gè)個(gè)反映迅速，總體知識(shí)要強(qiáng)，要求選手要在短短的時(shí)間內(nèi)做出對(duì)題目的判斷，而這其中就會(huì)遇到那方選手先答題的問題，以及答題的公正性

8、，如果單靠舉手，那個(gè)爭議太大了。必然會(huì)導(dǎo)致群眾的不滿，偏向有爭議，本來有趣的比賽便會(huì)多了些不開心的因素，讓人很不爽。但是搶答器的出現(xiàn)就使得這類的問題迎刃而解，不僅如此有了搶答器比賽將會(huì)更加的精彩美妙，不用擔(dān)心比賽的公正性，我們可以放心的投入到比賽當(dāng)中，盡情的展示我們的才華，釋放出自我的激情來。而那些不和諧的聲音將不會(huì)出現(xiàn)，想知道為什么嗎，這就是搶答器的魅力，而下面的文章當(dāng)中你便會(huì)了解到，為什么搶答器會(huì)有如此的神奇效果，其實(shí)這一切并不是很難，因?yàn)槠孥E都是來自于自然，而偉大總是出自平凡。近年來隨著科技的飛速發(fā)展, 單片機(jī)、PLC 的應(yīng)用正在不斷地走向深入, 同時(shí)帶動(dòng)傳統(tǒng)的控制檢測(cè)技術(shù)的不斷更新。當(dāng)

9、然搶答器的發(fā)展也是隨著時(shí)代的前進(jìn)不斷的完善。它更加的美觀，小型化，適用更多的需求，更能滿足人們的日常生活要求。而且現(xiàn)在的搶答器精準(zhǔn)度上的能力是大大的提高了。尤其是計(jì)算機(jī)的發(fā)展，使得搶答器已從原始的實(shí)體狀態(tài)走進(jìn)了軟件化，有了更廣泛的發(fā)展空間，更加的讓人期待了。本設(shè)計(jì)利用PLC(日本三菱FX2N 64MR 型) 制作的8 路搶答器,該搶答器集搶答、聲音警示、數(shù)碼顯示和答題計(jì)時(shí)于一體,借助較少的外圍元件完成搶答器的基本功能。該設(shè)計(jì)編程簡單,容易掌握，且工作穩(wěn)定可靠，具有結(jié)構(gòu)簡單、可靠性好、經(jīng)濟(jì)省錢等特點(diǎn)。定能使得競(jìng)賽真正達(dá)到公正、公平、公開。 第1章 PLC的概述1.1 PLC定義PLC即可編程序控

10、制器是一類專門為在工業(yè)環(huán)境下應(yīng)用而設(shè)計(jì)的數(shù)字式電子系統(tǒng)，它采用了可編程序的存儲(chǔ)器，用來在其內(nèi)部進(jìn)行存儲(chǔ)執(zhí)行邏輯運(yùn)算、順序運(yùn)算、定時(shí)、記數(shù)和算術(shù)運(yùn)算等功能的面向用戶的指令，并通過數(shù)字式或模擬式的輸入或輸出，控制各種類型的機(jī)械或生產(chǎn)過程?？杀槌绦蚩刂破鳂O其相關(guān)外部設(shè)備，都應(yīng)按照易于與工業(yè)控制系統(tǒng)聯(lián)成一個(gè)整體，易于擴(kuò)展其功能的原則而設(shè)計(jì)。定義強(qiáng)調(diào)了PLC應(yīng)直接應(yīng)用與工業(yè)環(huán)境，它必須具有很強(qiáng)的抗干擾能力，廣泛的適應(yīng)能力和應(yīng)用范圍。這也是區(qū)別與一般微機(jī)控制系統(tǒng)的一個(gè)重要特征。定義還強(qiáng)調(diào)了PLC是“數(shù)字運(yùn)算操作的電子系統(tǒng)”，他也是一種計(jì)算機(jī)，它是“專為在工業(yè)環(huán)境下應(yīng)用而設(shè)計(jì)的”工業(yè)計(jì)算機(jī)。這種工業(yè)計(jì)算機(jī)采

11、用“面向用戶的指令”，因此編程方便。它能完成邏輯運(yùn)算、順序運(yùn)算、定時(shí)、記數(shù)和算術(shù)運(yùn)算等操作，它還具有“數(shù)字量和模擬量輸入和輸出”的能力，并且非常容易與“工業(yè)控制系統(tǒng)聯(lián)成一體”，易于“擴(kuò)充”。 1.2 PLC發(fā)展趨勢(shì)PLC總的發(fā)展趨勢(shì)是向高集成度、小體積、大容量、高速度、易使用、高性能方向發(fā)展。具體表現(xiàn)在以下幾個(gè)方面。1、向小型化,專用化,低成本方向發(fā)展2、向大容量,高速度方向發(fā)展3、智能型I/O模塊的發(fā)展4、基于PC的編程軟件取代編程器5、PLC編程語言的標(biāo)準(zhǔn)化6、PLC通信的易用化7、組態(tài)軟件與PLC的軟件化8、PLC與現(xiàn)場(chǎng)總線相結(jié)合9、開發(fā)新型特殊功能模塊10、 CPU的處理速度進(jìn)一步加快

12、目前，PLC的處理速度與計(jì)算機(jī)相比還比較慢，其高的CPU也不過80486，將來會(huì)全面使用64位的RISC芯片，采用多CPU進(jìn)行處理、分時(shí)處理或分任務(wù)處理方式，將各種模塊智能化，部分系統(tǒng)程序用門陣列電路固化，這樣可使PLC的處理速度達(dá)到納秒級(jí)。1.3 PLC基本結(jié)構(gòu)及原理1、PLC的系統(tǒng)結(jié)構(gòu)，目前PLC種類繁多，功能和指令系統(tǒng)也都各不相同，但都是以微處理器為核心用做工業(yè)控制的專用計(jì)算機(jī)，所以其結(jié)構(gòu)和工作原理都大致相同，硬件結(jié)構(gòu)與微機(jī)相似。主要包括中央處理單元CPU、存儲(chǔ)器RAM和ROM、輸入輸出接口電路、電源、I/O擴(kuò)展接口、外部設(shè)備接口等。其內(nèi)部也是采用總線結(jié)構(gòu)來進(jìn)行數(shù)據(jù)和指令的傳輸。如圖1-

13、1所示，PLC控制系統(tǒng)由輸入量PLC輸出量組成，外部的各種開關(guān)信號(hào)、模擬信號(hào)、傳感器檢測(cè)的各種信號(hào)均作為PLC的輸入量，它們經(jīng)PLC外部輸入端子，作為PLC的輸出量對(duì)外圍設(shè)備進(jìn)行各種控制。由此可見，PLC的基本結(jié)構(gòu)有控制部分輸入和輸出組成。圖1-1 PLC硬件結(jié)構(gòu)圖2、 PLC的工作原理，PLC采用的是循環(huán)掃描工作方式。對(duì)每個(gè)程序，CPU從第一條指令開始執(zhí)行，按指令步序號(hào)做周期性的程序循環(huán)掃描，如果無跳轉(zhuǎn)指令，則從第一條指令開始逐條順序執(zhí)行用戶程序，直至遇到結(jié)束符后又返回第一條指令，如此周而復(fù)始不斷循環(huán)，每一個(gè)循環(huán)稱為一個(gè)掃描周期。PLC的掃描全過程如圖1-2所示。(1) 輸入刷新階段在輸入刷

14、新階段，CPU掃描全部輸入端口，讀取其狀態(tài)并寫入輸入狀態(tài)寄存器。完成后關(guān)閉輸入端口，轉(zhuǎn)入程序執(zhí)行階段。(2) 程序執(zhí)行階段 在程序執(zhí)行階段，根據(jù)用戶輸入的控制程序，從第一條開始逐條執(zhí)行，并將相應(yīng)的邏輯運(yùn)算結(jié)果存入對(duì)應(yīng)的內(nèi)部輔助寄存器和輸出狀態(tài)寄存器。(3) 輸出刷新階段當(dāng)所有指令執(zhí)行完畢后，將輸出狀態(tài)寄存器中的內(nèi)容，依次送到輸出鎖存電路，并通過一定輸出方式輸出，驅(qū)動(dòng)外部相應(yīng)執(zhí)行元件工作，這才形成PLC的實(shí)際輸出。 圖1-2 PLC的掃描全過程顯然掃描周期的長短主要取決與程序的長短。掃描周期越長，響應(yīng)速度越慢。由于每一個(gè)掃描周期只進(jìn)行一次I/O刷新，即每一個(gè)掃描周期PLC只對(duì)輸入、輸出狀態(tài)寄存器

15、更新一次，故使系統(tǒng)存在輸入、輸出滯后現(xiàn)象，這在一定程度上降低了系統(tǒng)的響應(yīng)速度。由此可見，若輸入變量在I/O刷新期間狀態(tài)發(fā)生變化，則本次掃描期間輸出會(huì)相應(yīng)地發(fā)生變化。反之，若在本次刷新之后輸入變量才發(fā)生變化，則本次掃描輸出不變，而要到下一次掃描的I/O刷新期間輸出才會(huì)發(fā)生變化。第2章 硬件電路設(shè)計(jì)2.1 搶答器的控制要求1、搶答器可同時(shí)供8組選手參加比賽；2、具有違規(guī)提示功能：只有在主持人發(fā)出開始信號(hào)， 選手才能開始搶答；3、具有搶答限時(shí)功能：在無人搶答及答題超時(shí)時(shí)設(shè)置提示信號(hào)； 4、具有數(shù)碼顯示功能：能顯示搶答選手的編號(hào)及答題倒計(jì)時(shí)時(shí)間。2.2 控制特點(diǎn)分析由控制要求分析可知，首先，所設(shè)計(jì)的搶

16、答器要有8路的選擇按鈕，供8組選手用來搶答。其次，主持人擁有總控的能力，即具有開始權(quán)，而在此之前所有的搶答是不和規(guī)矩的，因此電路要有復(fù)位功能及識(shí)別功能，要能分辨出正常和違規(guī)的作用。再次，時(shí)間的概念，無人答題或答題超時(shí)要有表示，這就要求定時(shí)器的運(yùn)用以及外部音響或指示燈的選擇問題。最后，關(guān)于選手的認(rèn)定也有要求，到底時(shí)那位選手，而選手之間不能有沖突，即一號(hào)搶了別的號(hào)就不能再搶答，這就要求設(shè)計(jì)電路要有互鎖環(huán)節(jié)，要有LED顯示識(shí)別等問題。2.3 FX2N系列PLC硬件認(rèn)識(shí)1、FX2N系列PLC外部結(jié)構(gòu)，F(xiàn)X2N系列PLC的硬件結(jié)構(gòu)可以參考圖2-1帶擴(kuò)展模塊的PLC；該圖為FX2N64MR的主機(jī)外形圖，其

17、面板部件如圖中注釋。圖2-1 FX2N系列PLC外表結(jié)構(gòu)2、詳細(xì)的I/O端子編號(hào)圖圖2-2 I/O 圖4 I/O端子編號(hào)圖由圖4可知，外部接線端子包括PLC電源（，）端子，輸入用直流電源（COM）端子，輸入點(diǎn)（X），輸出點(diǎn)（Y）和機(jī)器接地端子等。它位于機(jī)器兩側(cè)可拆卸的端子板上，每個(gè)端子均有對(duì)應(yīng)的編號(hào)，主要完成電源 輸入信號(hào)和輸出信號(hào)的連接。輸出側(cè)左端4個(gè)點(diǎn)共用一個(gè)COM端，右邊多輸出點(diǎn)共用一個(gè)COM端。圖2-2 /端子編號(hào)圖3、系列型號(hào)含義，在PLC的正面，一般都有表示該P(yáng)LC型號(hào)的文字符號(hào)，通過閱讀該符號(hào)就可以獲得該P(yáng)LC的基本信息。FX系列PLC的型號(hào)命名基本格式：例如，本設(shè)計(jì)所使用的含義

18、為系列，輸入輸出點(diǎn)數(shù)為64點(diǎn)，繼電器輸出。2.4 I/O口的分配及硬件接線圖1、根據(jù)設(shè)計(jì)要求,分析得出8路搶答器控制系統(tǒng)可分為5部分:2、PLC控制系統(tǒng);3、搶答器按鈕;4、信號(hào)燈;5、音響電路;6、顯示部分它利用強(qiáng)大按鈕輸入各路的搶答信號(hào)，經(jīng)PLC處理輸出控制信號(hào)，控制數(shù)碼管和音響提示電路。PLC的I/O端子分配圖如表2-1所示。表2-1 I/O端子分配圖元件名設(shè)備及作用X0-X7八路選手搶答器（）X10復(fù)位按鈕SB10X11開始強(qiáng)答按鈕SB11X12答題記時(shí)開始按鈕SB12Y0正常搶答綠色指示燈L1Y1違規(guī)搶答紅色指示燈L2Y2無人搶答黃色指示燈L3Y3正常搶答（音響電路1）Y4違規(guī)搶答報(bào)

19、警（音響電路2）Y5無人搶答報(bào)警（音響電路3）Y6答題超時(shí)報(bào)警（音響電路4）Y10-Y16七段數(shù)碼管1（a-g）Y20-Y26七段數(shù)碼管2（a-g）Y30-Y36七段數(shù)碼管3（a-g） 2、 根據(jù)控制要求，繪出硬件接線圖，如圖2-3所示。圖2-3硬件接線圖第3章 軟件程序設(shè)計(jì)3.1 梯形圖設(shè)計(jì)我們有了硬件接線圖，然后我們需要將所有的輸入輸出口，通過一定的方式有效地聯(lián)系起來，去達(dá)到我們要求的效果。這就需要相應(yīng)的軟件程序，PLC的程序有很多種，最常用的就是梯形圖，它類似與電氣控制的線路圖，看起來很直觀，便于理解很適合一線的技術(shù)工作人員，下面就是相應(yīng)的程序控制梯形圖，程序很好的解決了我們想要達(dá)到的效

20、果。系統(tǒng)控制部分及數(shù)碼管1顯示部分梯形圖，如圖3-1，3-2，3-3，3-4，3-5所示。3.2 工作過程分析1、每當(dāng)主持人發(fā)出開始搶答指令（即按下X11按鈕）后，那組選手最先按下?lián)尨鸢粹o，則數(shù)碼管1就顯示該組的編號(hào)，同時(shí)綠色指示燈亮，音響電路1給出音響提示信號(hào)（設(shè)持續(xù)3S），以指示搶答成功，并對(duì)其后的搶答信號(hào)不再響應(yīng)，選手答題完畢后，由主持人按下復(fù)位按鈕，系統(tǒng)才能開始下一輪搶答。2、違規(guī)搶答：若選手在未開始搶答時(shí)提前搶答了，則是為違規(guī)，違規(guī)時(shí)數(shù)碼管1顯示其編號(hào)，同時(shí)紅燈亮音響電路2發(fā)出聲響。3、搶答限時(shí)：當(dāng)主持人按下開始搶答按鈕后，定時(shí)器T0開始計(jì)時(shí)（設(shè)定時(shí)10S），若10S時(shí)限時(shí)仍無人搶答

21、，則黃燈亮，音響電路3發(fā)出聲響，以示選手放棄該題。4、答題限時(shí)：在搶答成功后，主持人按下答題計(jì)時(shí)開始按鈕SB12，秒脈沖輔助繼電器開始工作，并利用響應(yīng)的指令，使數(shù)碼管2，3上顯示答題倒計(jì)時(shí)，總時(shí)間是60秒，要求有10秒的倒計(jì)時(shí)，數(shù)碼管2顯示時(shí)間十位，數(shù)碼管3顯示時(shí)間個(gè)位，選手必須在設(shè)定時(shí)間內(nèi)玩笑答題，否則，音響電路4發(fā)出答題超時(shí)報(bào)警信號(hào)。5、執(zhí)行過程分析（1）正常搶答：PLC控制部分梯形圖，當(dāng)主持人按下SB11時(shí)，X11常開觸點(diǎn)閉合，相當(dāng)與線圈的輔助繼電器M0得電，M0常開觸點(diǎn)閉合，線路形成自鎖，時(shí)間繼電器T0得電，電路開始計(jì)時(shí)，時(shí)間為十秒。這時(shí)如果一號(hào)選手按下SB0，M1得電M1常開觸點(diǎn)閉合

22、，相當(dāng)與電機(jī)的Y0得電，Y0常開觸點(diǎn)閉合，T1開始計(jì)時(shí)時(shí)間為3秒，綠燈亮，音響電路1響起，3秒后T1常閉觸點(diǎn)斷開，Y3失電音響停止，正常搶答結(jié)束。（2）違規(guī)搶答：PLC控制部分梯形圖，當(dāng)主持人沒有按下SB11時(shí)，X11常開觸點(diǎn)不動(dòng)。M0未得電，M0的常閉觸點(diǎn)仍然處于閉合狀態(tài)，這時(shí)如果一號(hào)選手按下SB0，M1得電M1常開觸點(diǎn)閉合， Y1得電，Y1常開觸點(diǎn)閉合，T2開始計(jì)時(shí)時(shí)間為3秒，紅燈亮，音響電路2響起，3秒后T2常閉觸點(diǎn)斷開，Y4失電音響停止，違規(guī)搶答結(jié)束。（3）無人搶答：PLC控制部分梯形圖，當(dāng)主持人按下SB11時(shí)，X11常開觸點(diǎn)閉合，相當(dāng)與線圈的輔助繼電器M0得電，M0常開觸點(diǎn)閉合，線路

23、形成自鎖，時(shí)間繼電器T0得電，電路開始計(jì)時(shí)，時(shí)間為十秒。這時(shí)如果沒有選手按下SB0，M1未得電M1常閉觸點(diǎn)仍然為閉合狀態(tài)，十秒之后T0常開觸點(diǎn)閉合，相當(dāng)與電機(jī)的Y2得電，Y2常開觸點(diǎn)閉合，T3開始計(jì)時(shí)時(shí)間為3秒，黃燈亮，音響電路3響起，3秒后T3常閉觸點(diǎn)斷開，Y5失電音響停止，無人搶答結(jié)束。（4）最先搶答：幾個(gè)選手幾乎同時(shí)按下按鈕，如果一號(hào)選手最先按下了按鈕，由于M1得電，M1常閉觸點(diǎn)斷開，其他的選手電路便無法導(dǎo)通了。而在這之前一號(hào)選手的電路已經(jīng)導(dǎo)通了。（5）選手號(hào)顯示：如果一號(hào)選手最先按下按鈕，線圈M10得電，M10常開觸點(diǎn)閉合，如數(shù)碼管1顯示部分梯形圖，LED燈要求顯示為“1”，要求b，c

24、處的輸出端得電，即Y11，Y12得電。我們只需要將M10的常開觸點(diǎn)與其相連即可實(shí)現(xiàn)顯示，別的選手號(hào)碼顯示同理。（6）十秒倒計(jì)時(shí)：主持人按下SB12，X12常開觸點(diǎn)閉合M2得電，M2常開觸點(diǎn)閉合，如60秒答題控制梯形圖，T4時(shí)間繼電器得電先開始了50秒的答題時(shí)間。50秒之后，T4常開觸點(diǎn)閉合T5時(shí)間繼電器得電，計(jì)時(shí)時(shí)間為一秒，M18線圈得電。我們要求數(shù)碼管2，數(shù)碼管3上要顯示出“10”的數(shù)字，表示第十秒。即數(shù)碼管2的b，c端得電，數(shù)碼管3的a，b，c，d，e端得電。只需將相應(yīng)的輸出端口與M18常開觸點(diǎn)相連即可。道理同選手號(hào)碼顯示，T5計(jì)時(shí)到后，T5常閉觸點(diǎn)斷開，M18失電T5常開觸點(diǎn)閉合，T6計(jì)

25、時(shí)器開始計(jì)時(shí)，時(shí)間為一秒。數(shù)碼管2，3要顯示“09”，道理同上。當(dāng)T14時(shí)間繼電器得電一秒后，十秒倒計(jì)時(shí)結(jié)束，T14常開觸點(diǎn)閉合,T 15得電音響電路4得電，3秒后T15常閉觸點(diǎn)斷開，影響停止答題過程結(jié)束。 圖3-1PLC控制部分梯形圖 圖3-2數(shù)碼管1顯示部分梯形圖 圖3-3 60秒答題控制梯形圖圖3-4 數(shù)碼管2顯示部分梯形圖圖3-5 數(shù)碼管3顯示部分梯形圖結(jié)論本研究結(jié)果說明了，PLC可以實(shí)現(xiàn)搶答功能，而且過程簡單，方便。能夠準(zhǔn)確，公正，直觀地判斷出搶答者的意圖。我們可以使用PLC去設(shè)計(jì)八路搶答器，還可以用PLC去設(shè)計(jì)六路搶答器，四路搶答器。其道理是一樣的，當(dāng)然，不僅僅只限于搶答器，我們也

26、可以用其基本原理去設(shè)計(jì)其他的方案。搶答器關(guān)鍵解決了在幾個(gè)選手同時(shí)搶答時(shí)，要求選手之間不能有沖突，所以設(shè)計(jì)電路要有互鎖環(huán)節(jié)。主持人有總控權(quán)，電路要配備復(fù)位功能及識(shí)別能力。在顯示選手問題及倒計(jì)時(shí)問題上，我使用了較為簡單的方法。甚至將定時(shí)器時(shí)間分解到了秒，雖然理論上簡單易懂，但是程序較長，不夠簡單，未使用高級(jí)命令。我認(rèn)為像搶答器這類常用的設(shè)備，完全可以模板化，可以將其設(shè)計(jì)的更加靈活多樣。如果要用的話，只需略微調(diào)試一下便可，這樣不僅可以省去了時(shí)間，效率也會(huì)大大提高，更加方便我們的生活。謝 辭參考文獻(xiàn)1 肖明耀，王國海可，編程控制技術(shù)，北京中國勞動(dòng)社會(huì)保障出版社20042 吳明亮，蔡夕忠，可編程控制器實(shí)

27、訓(xùn)教程，北京化學(xué)工業(yè)出版社2005.63 ISBN 987-7-5083-5211-4 范永勝，王岷，電器控制與PLC應(yīng)用，中國電力出版社，20074 ISBN 987-7-118-05872-7 王庭有等，可編程控制器原理及應(yīng)用，國防工業(yè)出版社，2008.85 何強(qiáng)，4路搶答器的PLC程序設(shè)計(jì)，安徽水利水電職業(yè)技術(shù)學(xué)院學(xué)報(bào)200.6 李祥，周海濤，PLC設(shè)計(jì)在六路搶答器中的應(yīng)用，科技咨詢導(dǎo)報(bào) 20087 劉紅， PLC在知識(shí)搶答器中的應(yīng)用，科技咨詢導(dǎo)，2007.NO.288 陳群，基于PLC的八路搶答器，電工技術(shù)2007，第12期 48-49頁9 張桂香，機(jī)電類專業(yè)畢業(yè)設(shè)計(jì)指南J，北京：機(jī)械

28、工業(yè)出版社，2005.110 瞿大中，可編程控制與實(shí)驗(yàn)P，華中科技大學(xué)出版社,2002.12.11 殷建國，工廠電氣控制技術(shù)M，北京:經(jīng)濟(jì)管理出版社,2006.9.12 齊占慶，機(jī)床電氣控制技術(shù)G，北京:機(jī)械工業(yè)出版社,2006.1.13 余雷聲， 電器控制與PLC應(yīng)用M， 北京：機(jī)械工業(yè)出版社，1996：58-6314 程周，可編程控制器技術(shù)與應(yīng)用M，北京：電子工業(yè)出版社，2002.8：99-10215 郁漢琪，郭健，可編程序控制器原理及應(yīng)用M，北京：中國電力出版社，2004：88-9016 黃凈，電氣及PLC控制技術(shù)M，北京：機(jī)械工業(yè)出版社：7217 張萬忠，孫晉，可編程控制器入門與應(yīng)用實(shí)

29、例（三菱FX2N系列）M，北京：中國電力出版社，2005：86-98外文資料翻譯MACHINABILITYThe machinability of a material usually defined in terms of four factors:1.Surface finish and integrity of the machined part;2.Tool life obtained;3.Force and power requirements;4.Chip control. Thus, good machinability good surface finish and integ

30、rity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone.Because of the complex nature of cutting operations, it is difficult to

31、establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in

32、 the example below.1 Machinability Of SteelsBecause steels are among the most important engineering materials, their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels.Resulfurized and R

33、ephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of t

34、hese inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in resulfurized steels.Phosphorus in steels has two major effects. It strengthens the ferrite, causing increased hardness. Harder st

35、eels result in better chip formation and surface finish. Note that soft steels can be difficult to machine, with built-up edge formation and poor surface finish. The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones, thereby improving mac

36、hinability.Leaded Steels. A high percentage of lead in steels solidifies at the tip of manganese sulfide inclusions. In non-resulfurized grades of steel, lead takes the form of dispersed fine particles. Lead is insoluble in iron, copper, and aluminum and their alloys. Because of its low shear streng

37、th, therefore, lead acts as a solid lubricant (Section 32.11) and is smeared over the tool-chip interface during cutting. This behavior has been verified by the presence of high concentrations of lead on the tool-side face of chips when machining leaded steels.When the temperature is sufficiently hi

38、gh-for instance, at high cutting speeds and feeds (Section 20.6)the lead melts directly in front of the tool, acting as a liquid lubricant. In addition to this effect, lead lowers the shear stress in the primary shear zone, reducing cutting forces and power consumption. Lead can be used in every gra

39、de of steel, such as 10xx, 11xx, 12xx, 41xx, etc. Leaded steels are identified by the letter L between the second and third numerals (Note that in stainless steels, similar use of the letter L means “l(fā)ow carbon,” a condition that improves their corrosion resistance.)However, because lead is a well-k

40、nown toxin and a pollutant, there are serious environmental concerns about its use in steels (estimated at 4500 tons of lead consumption every year in the production of steels). Consequently, there is a continuing trend toward eliminating the use of lead in steels (lead-free steels). Bismuth and tin

41、 are now being investigated as possible substitutes for lead in steels.Calcium-Deoxidized Steels. An important development is calcium-deoxidized steels, in which oxide flakes of calcium silicates (CaSo) are formed. These flakes, in turn, reduce the strength of the secondary shear zone, decreasing to

42、ol-chip interface and wear. Temperature is correspondingly reduced. Consequently, these steels produce less crater wear, especially at high cutting speeds.Stainless Steels. Austenitic (300 series) steels are generally difficult to machine. Chatter can be s problem, necessitating machine tools with h

43、igh stiffness. However, ferritic stainless steels (also 300 series) have good machinability. Martensitic (400 series) steels are abrasive, tend to form a built-up edge, and require tool materials with high hot hardness and crater-wear resistance. Precipitation-hardening stainless steels are strong a

44、nd abrasive, requiring hard and abrasion-resistant tool materials.The Effects of Other Elements in Steels on Machinability. The presence of aluminum and silicon in steels is always harmful because these elements combine with oxygen to form aluminum oxide and silicates, which are hard and abrasive. T

45、hese compounds increase tool wear and reduce machinability. It is essential to produce and use clean steels.Carbon and manganese have various effects on the machinability of steels, depending on their composition. Plain low-carbon steels (less than 0.15% C) can produce poor surface finish by forming

46、 a built-up edge. Cast steels are more abrasive, although their machinability is similar to that of wrought steels. Tool and die steels are very difficult to machine and usually require annealing prior to machining. Machinability of most steels is improved by cold working, which hardens the material

47、 and reduces the tendency for built-up edge formation.Other alloying elements, such as nickel, chromium, molybdenum, and vanadium, which improve the properties of steels, generally reduce machinability. The effect of boron is negligible. Gaseous elements such as hydrogen and nitrogen can have partic

48、ularly detrimental effects on the properties of steel. Oxygen has been shown to have a strong effect on the aspect ratio of the manganese sulfide inclusions; the higher the oxygen content, the lower the aspect ratio and the higher the machinability.In selecting various elements to improve machinabil

49、ity, we should consider the possible detrimental effects of these elements on the properties and strength of the machined part in service. At elevated temperatures, for example, lead causes embrittlement of steels (liquid-metal embrittlement, hot shortness), although at room temperature it has no ef

50、fect on mechanical properties.Sulfur can severely reduce the hot workability of steels, because of the formation of iron sulfide, unless sufficient manganese is present to prevent such formation. At room temperature, the mechanical properties of resulfurized steels depend on the orientation of the d

51、eformed manganese sulfide inclusions (anisotropy). Rephosphorized steels are significantly less ductile, and are produced solely to improve machinability.2 Machinability of Various Other Metals Aluminum is generally very easy to machine, although the softer grades tend to form a built-up edge, resul

52、ting in poor surface finish. High cutting speeds, high rake angles, and high relief angles are recommended. Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive; they require harder tool materials. Dimensional tolerance control may be a problem in machining alum

53、inum, since it has a high thermal coefficient of expansion and a relatively low elastic modulus.Beryllium is similar to cast irons. Because it is more abrasive and toxic, though, it requires machining in a controlled environment.Cast gray irons are generally machinable but are. Free carbides in cast

54、ings reduce their machinability and cause tool chipping or fracture, necessitating tools with high toughness. Nodular and malleable irons are machinable with hard tool materials.Cobalt-based alloys are abrasive and highly work-hardening. They require sharp, abrasion-resistant tool materials and low

55、feeds and speeds.Wrought copper can be difficult to machine because of built-up edge formation, although cast copper alloys are easy to machine. Brasses are easy to machine, especially with the addition pf lead (leaded free-machining brass). Bronzes are more difficult to machine than brass.Magnesium

56、 is very easy to machine, with good surface finish and prolonged tool life. However care should be exercised because of its high rate of oxidation and the danger of fire (the element is pyrophoric).Molybdenum is ductile and work-hardening, so it can produce poor surface finish. Sharp tools are neces

57、sary.Nickel-based alloys are work-hardening, abrasive, and strong at high temperatures. Their machinability is similar to that of stainless steels.Tantalum is very work-hardening, ductile, and soft. It produces a poor surface finish; tool wear is high.Titanium and its alloys have poor thermal conductivity (indeed, the lowest of all metals), causing significant temperature