如何消除精密龍門磨床？“倒拖”的影響？

精(jing)密龍門磨(mo)床(chuang)用于研磨(mo)工(gong)件平(ping)面(mian)。在(zai)檢驗(yan)(yan)過程中，除按(an)照相關規(gui)(gui)范(fan)進行檢驗(yan)(yan)外(wai)，主(zhu)要(yao)按(an)照各(ge)種產品的(de)精(jing)度(du)、制造驗(yan)(yan)收技術標準和產品質量分類規(gui)(gui)范(fan)進行檢驗(yan)(yan)，檢驗(yan)(yan)貨物的(de)精(jing)度(du)和功能的(de)重點。由于各(ge)種商品的(de)加工(gong)精(jing)度(du)、功能規(gui)(gui)定和精(jing)度(du)水(shui)平(ping)不同，檢驗(yan)(yan)項目也不同。一般檢驗(yan)(yan)項目超過10個。

由(you)于精密龍(long)門磨(mo)(mo)機加(jia)工件(jian)的直徑較小，規定的導輪(lun)(lun)(lun)轉(zhuan)(zhuan)速也相對較低，便(bian)于降低晶閘管(guan)設備(bei)的輸出電壓和(he)負載能力。在(zai)具(ju)體(ti)生(sheng)產(chan)中，由(you)于空(kong)白偏差或其他(ta)原因，單位時間內的研磨(mo)(mo)量(liang)(liang)增加(jia)。砂(sha)(sha)輪(lun)(lun)(lun)研磨(mo)(mo)工件(jian)產(chan)生(sheng)的研磨(mo)(mo)力會改變導輪(lun)(lun)(lun)轉(zhuan)(zhuan)速。這(zhe)種情況稱為(wei)“倒(dao)拖(tuo)”。因為(wei)導輪(lun)(lun)(lun)被(bei)“倒(dao)拖(tuo)”當導輪(lun)(lun)(lun)轉(zhuan)(zhuan)速調整為(wei)20r/min在(zai)加(jia)工過(guo)程中，導輪(lun)(lun)(lun)的具(ju)體(ti)轉(zhuan)(zhuan)速將隨著砂(sha)(sha)輪(lun)(lun)(lun)的研磨(mo)(mo)速度(du)提高(gao)到10r/min，砂(sha)(sha)輪(lun)(lun)(lun)撤出磨(mo)(mo)削時，導輪(lun)(lun)(lun)轉(zhuan)(zhuan)速降至0。轉(zhuan)(zhuan)速波動達200%，嚴重危害產(chan)品(pin)質量(liang)(liang)和(he)生(sheng)產(chan)安全(quan)。

經檢查，變速系統(tong)各環節工(gong)作正常，輕(qing)載時導輪轉速可持(chi)續調整(zheng)。晶(jing)閘管在研磨(mo)時關閉(bi)的原因(yin)是電(dian)(dian)(dian)機(ji)被切斷“倒拖”而轉速升高(gao)，電(dian)(dian)(dian)流降低，使(shi)晶(jing)閘管設備的電(dian)(dian)(dian)壓(ya)小(xiao)于電(dian)(dian)(dian)機(ji)端的電(dian)(dian)(dian)壓(ya)，導致(zhi)晶(jing)閘管關閉(bi)。這時，電(dian)(dian)(dian)機(ji)實際上在發電(dian)(dian)(dian)機(ji)的情(qing)況(kuang)下工(gong)作。

為清除“倒拖”影(ying)(ying)響(xiang)，一旦計劃加(jia)載(zai)設備，這就(jiu)需要在(zai)機(ji)床上添(tian)加(jia)零件，結構就(jiu)會變得復雜。經過(guo)分析可(ke)知，“倒拖”當電(dian)(dian)(dian)機(ji)在(zai)發(fa)電(dian)(dian)(dian)機(ji)運(yun)行時(shi)(shi)。如果應用可(ke)逆系統的工作原理，此時(shi)(shi)應提供(gong)電(dian)(dian)(dian)流(liu)通道，使電(dian)(dian)(dian)樞電(dian)(dian)(dian)流(liu)反(fan)轉(zhuan)。然后，電(dian)(dian)(dian)機(ji)可(ke)以在(zai)高于(yu)(yu)給(gei)定(ding)速度(du)(du)的情況下(xia)進行制(zhi)動(dong)，從(cong)而達到穩(wen)定(ding)速度(du)(du)的目(mu)的。選擇(ze)直流(liu)電(dian)(dian)(dian)機(ji)兩側并(bing)連(lian)接(jie)電(dian)(dian)(dian)阻的方式，使導輪在(zai)轉(zhuan)速高于(yu)(yu)給(gei)出轉(zhuan)速時(shi)(shi)，為發(fa)電(dian)(dian)(dian)機(ji)情況下(xia)的電(dian)(dian)(dian)機(ji)提供(gong)制(zhi)動(dong)電(dian)(dian)(dian)流(liu)，限(xian)制(zhi)轉(zhuan)速增加(jia)，有效去(qu)除電(dian)(dian)(dian)機(ji)“倒拖”影(ying)(ying)響(xiang)，保持速度(du)(du)基本(ben)穩(wen)定(ding)。另外，在(zai)電(dian)(dian)(dian)阻電(dian)(dian)(dian)路中串聯開關，確保電(dian)(dian)(dian)阻僅在(zai)導輪低(di)速研磨時(shi)(shi)連(lian)接(jie)，以防(fang)止電(dian)(dian)(dian)阻在(zai)其他(ta)時(shi)(shi)間消耗能量。