應用PLC技術實現(xian)對機械手(shou)的控(kong)制，其任務是(shi)將工件從傳(chuan)送帶A搬運到傳(chuan)送帶B。采用移(yi)位指令設計順控(kong)程(cheng)序(xu)。

機(ji)械手的動作(zuo)示(shi)意圖(tu)(tu)如圖(tu)(tu)1所示(shi)，它是一(yi)個能(neng)夠產(chan)生水平/垂直位移的機(ji)械設備，用來將工件由左工作(zuo)臺(tai)搬運到右(you)工作(zuo)臺(tai)。

圖 1

1、工藝(yi)過(guo)程(cheng)與(yu)控制(zhi)要求

機(ji)械手(shou)(shou)的(de)全部動作由(you)氣缸(gang)驅動，而氣缸(gang)又由(you)相應的(de)電(dian)磁(ci)閥(fa)(fa)控制(zhi)(zhi)(zhi)。其中(zhong)，上(shang)升(sheng)(sheng)/下(xia)降(jiang)和(he)左(zuo)(zuo)轉(zhuan)/右轉(zhuan)分(fen)別由(you)雙線(xian)圈(quan)兩位電(dian)磁(ci)閥(fa)(fa)控制(zhi)(zhi)(zhi)。例如：當(dang)下(xia)降(jiang)電(dian)磁(ci)閥(fa)(fa)通(tong)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)下(xia)降(jiang)；當(dang)下(xia)降(jiang)電(dian)磁(ci)閥(fa)(fa)斷(duan)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)下(xia)降(jiang)停(ting)止(zhi)。只有當(dang)上(shang)升(sheng)(sheng)電(dian)磁(ci)閥(fa)(fa)通(tong)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)才上(shang)升(sheng)(sheng)；當(dang)上(shang)升(sheng)(sheng)電(dian)磁(ci)閥(fa)(fa)斷(duan)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)上(shang)升(sheng)(sheng)停(ting)止(zhi)。同樣，左(zuo)(zuo)轉(zhuan)/右轉(zhuan)分(fen)別由(you)左(zuo)(zuo)轉(zhuan)電(dian)磁(ci)閥(fa)(fa)和(he)右轉(zhuan)電(dian)磁(ci)閥(fa)(fa)控制(zhi)(zhi)(zhi)。機(ji)械手(shou)(shou)的(de)放松/夾(jia)(jia)緊(jin)由(you)一個(ge)單線(xian)圈(quan)兩位電(dian)磁(ci)閥(fa)(fa)(稱為夾(jia)(jia)緊(jin)電(dian)磁(ci)閥(fa)(fa))來控制(zhi)(zhi)(zhi)氣缸(gang)的(de)運動。當(dang)該線(xian)圈(quan)通(tong)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)夾(jia)(jia)緊(jin)；當(dang)該線(xian)圈(quan)斷(duan)電(dian)時(shi)(shi)(shi)(shi)，機(ji)械手(shou)(shou)放松。

當機械手右移到位并準備下降時，為了確保安全，必須在右工作臺無工件時才允許機械手下降。也就是說，若上一次搬運到右工作臺上的工件尚未搬走時，機械手應自動停止下降，用光電開關I0.5進行無工件檢測。

機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)的動(dong)作(zuo)過程如圖(tu)2所示。從(cong)原點(dian)開(kai)(kai)(kai)始，按下(xia)(xia)(xia)(xia)啟動(dong)按鈕，下(xia)(xia)(xia)(xia)降(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)下(xia)(xia)(xia)(xia)降(jiang)(jiang)。下(xia)(xia)(xia)(xia)降(jiang)(jiang)到(dao)(dao)底時(shi)(shi)，碰(peng)(peng)到(dao)(dao)下(xia)(xia)(xia)(xia)限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，下(xia)(xia)(xia)(xia)降(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，下(xia)(xia)(xia)(xia)降(jiang)(jiang)停(ting)(ting)(ting)(ting)止(zhi)；同時(shi)(shi)接(jie)(jie)通(tong)(tong)(tong)夾緊(jin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)夾緊(jin)。夾緊(jin)后，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)上(shang)(shang)(shang)升(sheng)(sheng)(sheng)。上(shang)(shang)(shang)升(sheng)(sheng)(sheng)到(dao)(dao)頂時(shi)(shi)，碰(peng)(peng)到(dao)(dao)上(shang)(shang)(shang)限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)停(ting)(ting)(ting)(ting)止(zhi)；同時(shi)(shi)接(jie)(jie)通(tong)(tong)(tong)右移電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)右移。右移到(dao)(dao)位(wei)時(shi)(shi)，碰(peng)(peng)到(dao)(dao)右限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，右移電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，右移停(ting)(ting)(ting)(ting)止(zhi)。若此時(shi)(shi)右工作(zuo)臺上(shang)(shang)(shang)無工件，則光電(dian)(dian)(dian)(dian)(dian)(dian)(dian)開(kai)(kai)(kai)關(guan)(guan)接(jie)(jie)通(tong)(tong)(tong)，下(xia)(xia)(xia)(xia)降(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)下(xia)(xia)(xia)(xia)降(jiang)(jiang)。下(xia)(xia)(xia)(xia)降(jiang)(jiang)到(dao)(dao)底時(shi)(shi)，碰(peng)(peng)到(dao)(dao)下(xia)(xia)(xia)(xia)限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，下(xia)(xia)(xia)(xia)降(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，下(xia)(xia)(xia)(xia)降(jiang)(jiang)停(ting)(ting)(ting)(ting)止(zhi)； 同時(shi)(shi)夾緊(jin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)放(fang)松。放(fang)松后，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)上(shang)(shang)(shang)升(sheng)(sheng)(sheng)。上(shang)(shang)(shang)升(sheng)(sheng)(sheng)到(dao)(dao)頂時(shi)(shi)， 碰(peng)(peng)到(dao)(dao)上(shang)(shang)(shang)限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，上(shang)(shang)(shang)升(sheng)(sheng)(sheng)停(ting)(ting)(ting)(ting)止(zhi)；同時(shi)(shi)接(jie)(jie)通(tong)(tong)(tong)左(zuo)(zuo)移電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)左(zuo)(zuo)移。左(zuo)(zuo)移到(dao)(dao)原點(dian)時(shi)(shi)，碰(peng)(peng)到(dao)(dao)左(zuo)(zuo)限(xian)位(wei)開(kai)(kai)(kai)關(guan)(guan)，左(zuo)(zuo)移電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)(ci)(ci)閥(fa)(fa)(fa)斷(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，左(zuo)(zuo)移停(ting)(ting)(ting)(ting)止(zhi)。至此，機(ji)械(xie)(xie)(xie)手(shou)(shou)(shou)經過八步動(dong)作(zuo)完成了(le)一(yi)個周(zhou)期的動(dong)作(zuo)。

圖 2

機械手的操(cao)(cao)作(zuo)(zuo)方(fang)式(shi)分為手動操(cao)(cao)作(zuo)(zuo)方(fang)式(shi)和(he)自(zi)動操(cao)(cao)作(zuo)(zuo)方(fang)式(shi)。自(zi)動操(cao)(cao)作(zuo)(zuo)方(fang)式(shi)又(you)分為步進、單周期和(he)連續操(cao)(cao)作(zuo)(zuo)三種(zhong)方(fang)式(shi)。

（1）手動(dong)(dong)操作(zuo)：就是(shi)用按(an)鈕(niu)操作(zuo)對機械手的每步運(yun)動(dong)(dong)單獨(du)進行控制。例如，當(dang)(dang)選擇(ze)(ze)上(shang)/下運(yun)動(dong)(dong)時，按(an)下啟動(dong)(dong)按(an)鈕(niu)，機械手下降；按(an)下停(ting)(ting)止(zhi)按(an)鈕(niu)，機械手上(shang)升。當(dang)(dang)選擇(ze)(ze)左/右運(yun)動(dong)(dong)時，按(an)下啟動(dong)(dong)按(an)鈕(niu)，機械手右移；按(an)下停(ting)(ting)止(zhi)按(an)鈕(niu)，機械手左移。當(dang)(dang)選擇(ze)(ze)夾緊/放松(song)運(yun)動(dong)(dong)時，按(an)下啟動(dong)(dong)按(an)鈕(niu)，機械手夾緊；按(an)下停(ting)(ting)止(zhi)按(an)鈕(niu)，機械手放松(song)。

（2）步進(jin)操(cao)作(zuo)：每按一次啟動按鈕(niu)，機械手完(wan)成一步動作(zuo)后(hou)自動停(ting)止。

（3）單周期操(cao)作：機械(xie)手(shou)從(cong)原點(dian)開始，按一(yi)下啟動(dong)按鈕，機械(xie)手(shou)自動(dong)完成一(yi)個周期的(de)動(dong)作后停止。

（4）連續(xu)操(cao)作(zuo)：機械(xie)手從(cong)原點開始，按(an)一下啟動(dong)(dong)按(an)鈕，機械(xie)手的動(dong)(dong)作(zuo)將(jiang)自(zi)動(dong)(dong)地、連續(xu)不斷(duan)地周期(qi)(qi)性(xing)循環。在工作(zuo)中若按(an)下停止按(an)鈕，則機械(xie)手將(jiang)繼續(xu)完成一個周期(qi)(qi)的動(dong)(dong)作(zuo)后(hou)，回到原點自(zi)動(dong)(dong)停止。

2、操作面板布置

圖(tu)3位操(cao)作(zuo)面板布置圖(tu)。

接通I0.7是單操作方式。按加載選擇開關的位置，用啟動/停止按鈕選擇加載操作，當加載選擇開關打到“左右”位置時，按下啟動按鈕，機械手右行;若按下停止按鈕，機械手左行。用上述操作可使機械手停在原點。

接通I1.0是步進方式。機械手在原點時，按下啟動按鈕，向前操作一步;每按啟動按鈕一次，操作一步。接通I1.1是單周期操作方式。機械手在原點時，按下啟動按鈕，自動操作一個周期。接通I1.2是連續操作方式。機械手在原點時，按下啟動按鈕，連續執行自動周期操作，當按下停止按鈕，機械手完成此周期動作后自動回到原點并不再動作。

圖 3

3、輸入/輸出(chu)端子地(di)址(zhi)分配機械手控制系統所采用的PLC是德國西門子公司生產的S7-200CPU214，圖4是S7-200 CPU214輸入/輸出端子地址分配圖。該機械手控制系統共使用了14個輸入量，6個輸出量。

圖 4

4、整體程(cheng)序結(jie)構

機械手的整體程序結構如圖5所示。若選擇單操作工作方式，I0.7斷開,接著執行單操作程序。(單操作程序可以獨立于自動操作程序，可另行設計)。

在單(dan)周(zhou)期工作方(fang)式(shi)和(he)連續操作方(fang)式(shi)下(xia)，可(ke)執(zhi)行自(zi)動(dong)(dong)操作程序(xu)。在步(bu)進(jin)工作方(fang)式(shi)，執(zhi)行步(bu)進(jin)操作程序(xu)，按(an)一下(xia)啟動(dong)(dong)按(an)鈕執(zhi)行一個動(dong)(dong)作，并(bing)按(an)規(gui)定順序(xu)進(jin)行。

在需要自動操作方式時，中間繼電器M1.0接通。步進工作方式、單操作工作方式和自動操作方式，都用同樣的輸出繼電器。