機(jī)械專業(yè)畢業(yè)設(shè)計(jì)（論文）外文翻譯圓型經(jīng)編機(jī)的偽造伺服系統(tǒng)

1、圓型經(jīng)編機(jī)的偽造伺服系統(tǒng)摘要經(jīng)編技術(shù)通常都是運(yùn)用在直絲(線性)經(jīng)編機(jī)上的。使用一種新概念的錐形針床并附上凸輪驅(qū)動(dòng)模式圓環(huán)的圓型經(jīng)編機(jī)，最近成為一種可能。這需要一個(gè)機(jī)械聯(lián)動(dòng)傳遞的凸輪運(yùn)動(dòng)模式,但很容易產(chǎn)生環(huán)振動(dòng)的不良水平。新一代的設(shè)計(jì)中取代機(jī)械凸輪和聯(lián)動(dòng)高速無(wú)刷直流伺服電機(jī)，使圖案的精確成為無(wú)限可能。經(jīng)報(bào)道，方法選擇的基于最大程度的減少了伺服電機(jī)的功率以及完成最快的運(yùn)動(dòng)要求。通過(guò)選擇最小合適的指定應(yīng)用伺服電機(jī)驅(qū)動(dòng)的方法保證了成本最小化。經(jīng)報(bào)道,一個(gè)圓型經(jīng)編機(jī)采用伺服電機(jī)以及其驅(qū)動(dòng)機(jī)器使用方法的選定設(shè)計(jì)、建造,并測(cè)試使用成功。2001科學(xué)出版社有限公司。保留所有權(quán)利。簡(jiǎn)介:模式機(jī)制概述直絲經(jīng)編機(jī)使

2、用了三個(gè)主要機(jī)制產(chǎn)生制針過(guò)程。針織機(jī)制針即是前邊垂直擺動(dòng)筒子紗的機(jī)制從前線移動(dòng)到后面的針和一個(gè)移針距機(jī)制產(chǎn)生重疊，然后和從下面露出的平面針進(jìn)行平行鋪設(shè)。這臺(tái)機(jī)器的模式在最大程度上取決于動(dòng)作的難易修改它的每個(gè)移針距形成的機(jī)理和字符串的長(zhǎng)度鏈。經(jīng)編針周期在針織機(jī)上可以被描述成六個(gè)階段(見(jiàn)圖1)。從針在他們的最高位置,有以前的循環(huán)圓自己干,在階段(1)從后面紗線擺動(dòng)到前面的針。在階段(2)下一個(gè)線程被鋪設(shè)的鉤子表演,而一針一針從側(cè)身空間到下一個(gè)的重疊。然后擺動(dòng)的紗線的回到了針的平臺(tái)(3)。然后就開(kāi)始移動(dòng)針向下,舊的環(huán)路的每一針被鎖住的,導(dǎo)致柜子的關(guān)閉。這些針繼續(xù)向下移動(dòng),直到老循環(huán)到達(dá)山頂?shù)尼?(階

3、段(4),拉動(dòng)了織物張力。在階段(5),下面織針的線程再一次,這一次后面的針重復(fù)。(階段(6),線程在鉤子上打開(kāi)柜子,成為下一個(gè)循環(huán)。在圓型經(jīng)編機(jī)上，紗線接頭都是通過(guò)非穿孔環(huán)。旋轉(zhuǎn)運(yùn)動(dòng)的成為與圖案,這些環(huán)鏈?zhǔn)怯啥喾N旋轉(zhuǎn)運(yùn)動(dòng)與圓環(huán)在同步的主要機(jī)制負(fù)責(zé)往復(fù)式針縱向(見(jiàn)圖2),戒指必須履行的兩種截然不同的輪換和兩個(gè)住在機(jī)器周期。今后的研究方向和幅值的旋轉(zhuǎn)將取決于織物結(jié)構(gòu)產(chǎn)生的吧。然而,一份重疊總是會(huì)進(jìn)行過(guò)超過(guò)一針,而一個(gè)只可在幾針并且可以因此需要一個(gè)更大的輪換的戒指。大的數(shù)目的戒指,可能性更大的模式。然而,一定數(shù)量的空間放置他們和紗線的路徑的復(fù)雜度的數(shù)量一般限制環(huán)中存在模式的機(jī)器。系統(tǒng)要求第一次設(shè)計(jì)

4、原型被用來(lái)當(dāng)作工業(yè)針織機(jī)生產(chǎn)包裝面料、長(zhǎng)統(tǒng)襪繃帶材料和其他技術(shù)紡織品。產(chǎn)品設(shè)計(jì)規(guī)格為機(jī)器覆蓋所有這些市場(chǎng)中實(shí)施,從而建立起企業(yè)終端產(chǎn)品的要求。研究發(fā)現(xiàn),大多數(shù)應(yīng)用程序不需要多于一個(gè)4倍下去針距。此外,最小規(guī)格(每英寸的針數(shù))在相關(guān)應(yīng)用四歲。氣缸的直徑是不重要的,這種情況在組網(wǎng)應(yīng)用的范圍為75100毫米的長(zhǎng)統(tǒng)襪,這完全是因人而異的應(yīng)用和廣泛的應(yīng)用于醫(yī)學(xué)應(yīng)用。為第一原型,75mm直徑缸使用。這個(gè)尺寸缸、四針空間四針每英寸相當(dāng)于38氣缸。一個(gè)4針距將可能需要的旋轉(zhuǎn)8針空間,相當(dāng)于76。這也正是決定向以及系統(tǒng)的要求,即模式機(jī)制必須能完成多達(dá)80的旋轉(zhuǎn),在一個(gè)單一的下針距。設(shè)計(jì)師可以改變織物的編織周期的

5、一部分分配給模式和企業(yè)生態(tài)位重疊動(dòng)作。在初步設(shè)計(jì)圓形的助燃機(jī),三分之一的機(jī)器周期被認(rèn)為是sucient為針的運(yùn)動(dòng)。這使得三分之二的針織周期來(lái)執(zhí)行120和重疊互相矛盾。假設(shè)的最大速度是1000轉(zhuǎn)數(shù),這臺(tái)機(jī)器單一針織循環(huán)發(fā)生在60歲的女士。這樣只剩下20 ms履行重疊和20的旋轉(zhuǎn)。機(jī)械解決辦法其專利模式機(jī)制2、5都是機(jī)械控制模式,使用兩個(gè)凸輪控制的開(kāi)放,面對(duì)環(huán)模式和有最大長(zhǎng)度的12機(jī)周期。人數(shù)限制周期是由于空間限制。較大數(shù)量的機(jī)器周期模式里需要一個(gè)更大的凸輪的空間,但在凸輪的大小是有限的。主要的進(jìn)步達(dá)到與機(jī)械方法解決建設(shè)作為本研究之部分:(1)使用封閉模式凸輪凸輪追隨者,減少?zèng)_擊和振使用開(kāi)放,面對(duì)

6、凸輪時(shí)形成的,(2)改進(jìn)的生產(chǎn)工藝模式的凸輪通過(guò)開(kāi)發(fā)一個(gè)特制的工具建立出銑削程序的模式,(3)凸輪機(jī)構(gòu)的凸輪性能提高利用擺線針輪箴les的每一個(gè)片段。擺線針輪剖面進(jìn)行已知能給你最好的結(jié)果為高速應(yīng)用3相比其他基本位移曲線,因?yàn)樗鼈兲峁┝巳N有限的衍生品的位移。給出了擺線針輪位移。唯一的缺點(diǎn),使用這種類型的職業(yè)樂(lè)為當(dāng)前的應(yīng)用是基于混球曲線的結(jié)束點(diǎn)的各運(yùn)動(dòng)。也就是說(shuō),在節(jié)點(diǎn)處上升(或收益)期間結(jié)束時(shí)期開(kāi)始和居住。這是因?yàn)榈谌N派生的位移不為零,而在終點(diǎn)的住。如果有必要,運(yùn)動(dòng)曲線可能會(huì)有進(jìn)一步的優(yōu)化利用poly-nomial檔案,來(lái)確保位移及其三個(gè)衍生物是連續(xù)貫穿始終。研制了一種特制的計(jì)算機(jī)應(yīng)用程序,

7、創(chuàng)造出一種凸輪廓線,然后再下載到一個(gè)數(shù)控銑床。一旦在針織機(jī)、凸輪運(yùn)動(dòng)中是使用高速lmed錄像機(jī)(200幀每秒)。沒(méi)有過(guò)多的振動(dòng);即使追隨者幀觀看時(shí)都已經(jīng)看到,跟隨者的沒(méi)有離開(kāi)一側(cè)的軌道上,這是滾動(dòng)。機(jī)械系統(tǒng)的作用是:將創(chuàng)造的直線移動(dòng)模式的旋轉(zhuǎn)凸輪進(jìn)一環(huán)通過(guò)模式有一定數(shù)量的樞紐和機(jī)械連接(見(jiàn)圖2)。組件和長(zhǎng)度的聯(lián)系在很大程度上取決于身體的可用空間和尺寸對(duì)機(jī)器零件的制造和銷售。例如,為了創(chuàng)造出一個(gè)長(zhǎng)循環(huán)運(yùn)動(dòng)的模式由環(huán),同時(shí)保持適當(dāng)?shù)膲毫堑耐馆?、基線半徑等一定增加。雖然凸輪機(jī)構(gòu)跑光滑,高速的視頻顯示過(guò)度振動(dòng)模式的戒指。對(duì)比的平穩(wěn)運(yùn)行和不規(guī)則的凸輪機(jī)構(gòu)從動(dòng)件運(yùn)動(dòng)圓環(huán)表明,后者是由彈性機(jī)械連接。機(jī)器的

8、速度會(huì)因此總是會(huì)受到其力學(xué)性能和尺寸的連接。證明了這種機(jī)械的設(shè)計(jì)概念的圓形經(jīng)編機(jī)制是可行的。伺服控制系統(tǒng)一種全新的方法是控制模式的機(jī)理問(wèn)題采用伺服電機(jī)的環(huán)。雖然更昂貴的解決方案,它具有潛在地產(chǎn)生模式鏈條,只是大小限制的記憶(i.e.hundreds用五機(jī)械周期而不是12個(gè)機(jī)械周期)和縮短了時(shí)間和部分從一個(gè)模式需要改變到另一個(gè)地方。此外,伺服電機(jī),會(huì)產(chǎn)生一種旋轉(zhuǎn)運(yùn)動(dòng),當(dāng)耦滑輪組可以駕駛模式環(huán)直接。沒(méi)有必要機(jī)械轉(zhuǎn)型到一個(gè)旋轉(zhuǎn)的一個(gè)直線移動(dòng),則可能是要求如果其他的電子控制線性驅(qū)動(dòng)的機(jī)械設(shè)備,使用,如線性氣動(dòng)執(zhí)行機(jī)構(gòu)。被選擇的伺服電機(jī)的步進(jìn)電機(jī)由于反應(yīng)的速度和位置控制要求給出的針織的申請(qǐng)。本文涉及的伺

9、服控制的模式機(jī)制而已。但是,主要機(jī)制,即針織負(fù)責(zé)針運(yùn)動(dòng)也可以通過(guò)伺服系統(tǒng)給予更多的控制之間的同步針和紗線。6提出一種提高動(dòng)態(tài)特性,通過(guò)控制的凸輪機(jī)構(gòu)從動(dòng)件凸輪的使用伺服電機(jī)的速度?；谥本€電機(jī)的經(jīng)編機(jī)橫移控制系統(tǒng)設(shè)計(jì)摘要 本文以三相永磁無(wú)刷直流直線電機(jī)及驅(qū)動(dòng)控制系統(tǒng)為主要研究對(duì)象，采用數(shù)字信號(hào)處理器(dsp)為控制核心對(duì)經(jīng)編機(jī)橫移機(jī)構(gòu)進(jìn)行實(shí)用設(shè)計(jì)。文中給出了系統(tǒng)的總體設(shè)計(jì)方案，闡述了該系統(tǒng)的基本結(jié)構(gòu)、工作原理、運(yùn)行特性及其設(shè)計(jì)方法。另外，文中還對(duì)各硬件模塊(直線電機(jī)驅(qū)動(dòng)電路、位置檢測(cè)電路、電流檢測(cè)等)電路設(shè)計(jì)以及各軟件模塊進(jìn)行了詳細(xì)的分析。關(guān)鍵詞：經(jīng)編機(jī)；橫移運(yùn)動(dòng)；直線電機(jī)；dsp；pwm；p

10、id1 引言經(jīng)編丁業(yè)是紡織工業(yè)的一個(gè)重要組成部分，經(jīng)編產(chǎn)業(yè)的快速發(fā)展推動(dòng)了經(jīng)編機(jī)設(shè)備制造技術(shù)的不斷更新。開(kāi)發(fā)和研制出技術(shù)含量高、生產(chǎn)效率高、可靠性高的高檔智能化經(jīng)編機(jī)，核心技術(shù)是需要經(jīng)編機(jī)梳櫛橫移精度高，因?yàn)楦呔鹊臋M移機(jī)構(gòu)在回復(fù)運(yùn)動(dòng)過(guò)程中，可以保證織針回?cái)[過(guò)相應(yīng)的導(dǎo)紗針時(shí)，一個(gè)橫移時(shí)間就完成。因此開(kāi)發(fā)和研制出智能化的高精度經(jīng)編機(jī)意義深遠(yuǎn)。2 當(dāng)前的經(jīng)編機(jī)橫移機(jī)構(gòu)控制系統(tǒng)21機(jī)械式經(jīng)編機(jī)橫移機(jī)構(gòu) 機(jī)械式多梳櫛提花經(jīng)編機(jī)是由高低尺寸不一的鏈塊縱橫排列成鏈帶，編織花型時(shí)該鏈帶循環(huán)走動(dòng)，按照花型的要求控制著梳櫛的行程以達(dá)到編織花型的目的。這種橫移機(jī)構(gòu)的缺點(diǎn)是一種花型就要一種凸輪(或花紋鏈條)，凸輪(

11、或花紋鏈條)加工成本高，花型變化品種有限，且代價(jià)昂貴。另外，由于人們對(duì)花型要求越來(lái)越高，梳櫛數(shù)進(jìn)一步增加，生產(chǎn)和改變花型已經(jīng)變得越來(lái)越困難。在多品種、小批量的買方市場(chǎng)下，用鏈條來(lái)進(jìn)行花型生產(chǎn)非常費(fèi)事、費(fèi)時(shí)，且成本很高。22新型電子橫移機(jī)構(gòu)新型的el(electronic guide baf control system)橫移機(jī)構(gòu)、su(summe blech)橫移機(jī)構(gòu)、鋼絲花梳橫移機(jī)構(gòu)、地梳和賈卡梳橫移機(jī)構(gòu)均采用伺服電機(jī)控制。el適用于連續(xù)的、快速的花型變換。機(jī)器速度受到限制。su橫移機(jī)構(gòu)借助滑動(dòng)組件來(lái)控制花梳，通過(guò)電磁元件來(lái)控制滑動(dòng)組件，從而可按照確定的路徑來(lái)形成橫移路徑距離。但是它的極限是

12、最大47針的橫移距離和每分鐘450轉(zhuǎn)的最大轉(zhuǎn)速。新型的鋼絲花梳、地梳和賈卡梳橫移機(jī)構(gòu)都采用了伺服電機(jī)控制。每個(gè)鋼絲花梳連接一個(gè)伺服電機(jī)，由伺服電機(jī)執(zhí)行橫移運(yùn)動(dòng)，鋼絲梳通過(guò)空氣壓縮機(jī)進(jìn)行回復(fù)。另一端的反向平衡裝置(氣動(dòng)張力調(diào)整器)保證鋼絲梳在整個(gè)橫移區(qū)間的張力均勻一致。導(dǎo)紗針按照花型進(jìn)行運(yùn)動(dòng)，一個(gè)方向借助壓縮空氣，另一個(gè)方向通過(guò)機(jī)械動(dòng)力，大小由伺服電機(jī)控制(如圖2)。另外，karl mayer公司新近研制出了匹艾州壓電式賈卡裝置。它是由壓電陶瓷及賈卡導(dǎo)紗針組成。壓電式賈卡導(dǎo)紗技術(shù)徹底改變了賈卡裝置，無(wú)需通絲、移位針等繁雜部件，使賈卡經(jīng)編機(jī)提花部分的機(jī)構(gòu)大大簡(jiǎn)化，有助提高速度。但是橫移距離較小。3

13、 系統(tǒng)總體結(jié)構(gòu)設(shè)計(jì)31系統(tǒng)方案的選取針對(duì)上面所闡述的當(dāng)前幾種經(jīng)編機(jī)橫移機(jī)構(gòu)，本文采用基于直線電機(jī)的橫移控制系統(tǒng)，利用直線電機(jī)取代花紋鏈塊直接驅(qū)動(dòng)導(dǎo)紗梳(如圖3)。由直線電機(jī)驅(qū)動(dòng)的傳動(dòng)裝置，不需要任何轉(zhuǎn)換裝置而直接產(chǎn)生推力，因此，它可以省去中間轉(zhuǎn)換機(jī)構(gòu)，簡(jiǎn)化了整個(gè)裝置或系統(tǒng)，保證了運(yùn)行的可靠性，提高了傳遞效率，降低了制造成本。另外，由dsp構(gòu)成的電機(jī)控制系統(tǒng)相對(duì)于單片機(jī)或微機(jī)具有更高的精度和速度，而且存儲(chǔ)量大，具有邏輯控制功能和各種中斷處理能力，豐富的數(shù)輸入輸出口、通信口、專用電機(jī)控制pwm輸出口，各種硬件集成在同一芯片中，從而簡(jiǎn)化硬件設(shè)計(jì)，提高軟件編程的靈活性。整個(gè)系統(tǒng)結(jié)構(gòu)簡(jiǎn)單、體積小、可靠性

14、高，實(shí)現(xiàn)真正意義上的機(jī)電一體化新型高精度經(jīng)編機(jī)橫移機(jī)構(gòu)控制系統(tǒng)。32系統(tǒng)總體結(jié)構(gòu)框圖本系統(tǒng)采用直線電機(jī)型號(hào)為深圳大族精密機(jī)電有限公司生產(chǎn)的lmcum20420，其最大行程為300mm，連續(xù)推力可達(dá)73n，最大電流18a?？梢院芎玫臐M足經(jīng)編機(jī)橫移的要求。控制器采用采用ti公司生產(chǎn)專用于電機(jī)控制的tms320lf2407a?；赿sp的直流直線電機(jī)控制系統(tǒng)的系統(tǒng)框圖如圖4所示，dsp負(fù)責(zé)處理采集到的數(shù)據(jù)和發(fā)送控制命令并通過(guò)捕獲單元捕捉電動(dòng)機(jī)動(dòng)子位置傳感器上的脈沖信號(hào)，判斷動(dòng)子位置，輸出合適的驅(qū)動(dòng)邏輯電平至星型全橋mosfet電路，再由mosfet功率驅(qū)動(dòng)電路驅(qū)動(dòng)電機(jī)做直線運(yùn)動(dòng)；dsp的捕獲單元根據(jù)

15、捕獲的位置傳感器脈沖信號(hào)的寬度，計(jì)算出電機(jī)的當(dāng)前轉(zhuǎn)速，與電機(jī)的設(shè)定轉(zhuǎn)速比較后，利用pid算法產(chǎn)生合適的脈寬調(diào)制信號(hào)(pwm)控制電機(jī)的轉(zhuǎn)速跟隨轉(zhuǎn)速的設(shè)定值；驅(qū)動(dòng)保護(hù)電路可完成電機(jī)的過(guò)載、欠壓、過(guò)壓等異常故障保護(hù)。4系統(tǒng)硬件電路實(shí)現(xiàn)41直線電機(jī)驅(qū)動(dòng)電路驅(qū)動(dòng)電路設(shè)計(jì)采用三相星型全橋電路。全橋逆變電路采用六個(gè)irf640搭建，在每個(gè)管子的基極和發(fā)射極之間并接一個(gè)嵌位電阻。電機(jī)前置功率管驅(qū)動(dòng)電路采用ir2130，ir2130芯片的每6路輸出控制驅(qū)動(dòng)電路的上半橋和下半橋?qū)P(guān)斷，從而控制控制電機(jī)的轉(zhuǎn)速和正反方向橫移，同時(shí)起到過(guò)載、欠壓、過(guò)壓等異常故薛保護(hù)。由ir2130和mosfet組成的電機(jī)驅(qū)動(dòng)電路如

16、圖5所示。圖5三相星型全橋式電機(jī)驅(qū)動(dòng)電路圖42位置檢測(cè)電路在直線電機(jī)的控制系統(tǒng)中，要實(shí)現(xiàn)對(duì)直線位移的精確控制，就必須通過(guò)高精度的檢測(cè)裝置對(duì)它進(jìn)行檢測(cè)，將檢測(cè)結(jié)果轉(zhuǎn)換成數(shù)字量反饋給dsp，由dsp對(duì)這些數(shù)據(jù)進(jìn)行處理。系統(tǒng)使用直線光柵傳感器進(jìn)行電機(jī)位置檢測(cè)。光柵位置檢測(cè)裝置由光源、兩塊光柵(長(zhǎng)光柵、短光柵)和光敏元件等組成。如果將指示光柵在其自身的平面內(nèi)轉(zhuǎn)過(guò)一個(gè)很小的角度0，這樣兩光柵的刻線相交，則在相交處出現(xiàn)黑色條紋，稱為莫爾條紋。由于兩塊光柵的刻線密度相等，即柵距w相等，而產(chǎn)生的莫爾條紋的方向和光柵刻線方向大致垂直，所以當(dāng)o很小時(shí)，其條紋間b和光柵柵距w及2條光柵刻線夾角關(guān)系為：當(dāng)光柵相對(duì)移動(dòng)

17、時(shí)，莫爾條紋將沿著刻線方向移動(dòng)。光柵移動(dòng)一個(gè)柵距，莫爾條紋也移動(dòng)一個(gè)間距b，同時(shí)；在指示光柵上的光敏元件接收到一次光脈沖的照射，并相應(yīng)輸出1個(gè)電脈沖。通過(guò)計(jì)數(shù)電脈沖的數(shù)目，就可以測(cè)量標(biāo)尺光柵的位移x，即： x=iw （2）43電流檢測(cè)電路采用wbl414電流傳感器作為電流檢測(cè)裝置，由于三相繞組采用的是星形連接，中點(diǎn)懸空，也就是說(shuō)，電流的3個(gè)變量不完全獨(dú)立，只要知道其中兩個(gè)，設(shè)為ia和ib，另一個(gè)變量ic就可以算出：因而實(shí)現(xiàn)電動(dòng)機(jī)相電流的精確檢測(cè)，只需兩路檢測(cè)電路，將ia和ib的電流值經(jīng)轉(zhuǎn)換后分別送往dsp的adcino和adcinl。電流檢測(cè)原理圖如圖6所示。位置檢測(cè)不但用于換向控制，而且還用

18、于產(chǎn)生速度控制量。每個(gè)周期內(nèi)有6次換相，電機(jī)的動(dòng)子每走過(guò)一塊磁鐵都有一次換相(每塊磁鐵的長(zhǎng)度15mm)，這樣測(cè)得兩次換相的時(shí)間間隔為t，就可以根據(jù)式(31)計(jì)算出兩次換相間隔期間的平均角速度。兩次換相的時(shí)間間隔t可以通過(guò)捕捉中斷發(fā)生時(shí)讀出定時(shí)器2的值來(lái)獲得。圖6 電流檢測(cè)電路圖5 dsp控制系統(tǒng)軟件實(shí)現(xiàn)主程序的主要功能足完成系統(tǒng)的初始化，如系統(tǒng)ram的映射(存儲(chǔ)空間的分配)、看門(mén)狗初始化、中斷初始化、i0引腳功能初始化、事件管理器eva的pwm，adc初始化、事件管理器evb的cap初始化、異步串行口初始化等。初始化完成后，主程序在ram中建立基準(zhǔn)正弦函數(shù)表，該正弦釃數(shù)表是對(duì)幅值為l正弦函數(shù)正

19、半周期采樣900個(gè)點(diǎn)得到的。圖7主程序流程框圖6 結(jié)論本文以tms320lf2407a作為控制器。對(duì)紡織機(jī)械電子橫移系統(tǒng)的電子凸輪機(jī)構(gòu)進(jìn)行了實(shí)用設(shè)計(jì)。系統(tǒng)充分利用直線電機(jī)的優(yōu)點(diǎn)，采用電流環(huán)、速度環(huán)的雙閉環(huán)控制電極的位置和速度，pid算法對(duì)參數(shù)進(jìn)行反復(fù)優(yōu)化，使系統(tǒng)達(dá)到預(yù)期的位移控制精度和頻率響應(yīng)，并且在經(jīng)編機(jī)電子橫移系統(tǒng)上運(yùn)行可靠。patterning servo-mechanism for a circular warp knitting machineabstractwarp knitting is always performed on flat (linear) knitting mac

20、hines. a circular warp-knitting machine is recently made possible by using a novel concept of a conical needle bed and patterning cams with enclosed cam followers to drive the patterning rings. this also requires a mechanical linkage to transmit the motion from the patterning cam to the patterning r

21、ings, which is prone to vibration at undesirable levels. a new generation design replaces the mechanical cam and linkage with high-speed ac brushless servomotors enabling limitless precision patterning possibilities. a method of selecting servomotors based on minimising the power required to perform

22、 the fastest motion required for a given application is reported. this method ensures cost minimising by selecting the smallest servomotor suitable for a given application. a circular warp-knitting machine using servomotor to drives selected using the method reported is designed, built and successfu

23、lly tested.2001 elsevier science ltd. all rights reserved.introduction: patterning mechanism overviewflat warp knitting machines employ three main mechanisms to produce stitches.namely, a knitting mechanism that reciprocates the needles vertically, a swingingmechanism to move the yarns from the fron

24、t to the back of the needles and ashogging mechanism to produce the overlaps and underlaps parallel to the plane on which the needles are laid.a pattern consists of a chain of dierent length underlaps and hence theexibilityof the machine patterning depends on the ease of modifying the movements per-

25、formed by its shogging mechanism and the length of the pattern chain.the warp knitting needle cycle for a at knitting machine can be described ascomprising six stages (see fig. 1). starting with the needles at their highest position and having the previous loops round their stem, in stage (1) the ya

26、rns are swung from the back to the front of the needles. at stage (2), the overlap, a thread is laid under the hook of the needle by performing a sideways shog from one needle space to the next. the yarns are then swung to the back of the needle in stage (3). the needles then start to move downwards

27、, the old loops are caught under each needle latch and cause the latches to close. the needles continue moving down until the old loops reach the top of the needle, are cast-o (stage (4) and pulled by fabric tension. at stage (5), theunderlap, the threads are shogged again, this time behind the need

28、les.as the needles rise again (stage (6), the threads in the hooks open the latches and become the next loops.on a circular machine, the yarns are threaded through radially perforated rings.the shogging movement becomes a rotation of these rings and a pattern chain comprises a number of rotational m

29、ovements of the rings in synchronisation with the main mechanism responsible for reciprocating the needles vertically (see fig. 2).the rings must perform two distinct rotations and two dwells during a machine cycle. the direction and amplitude of the rotations will depend upon the fabric structure b

30、eing created. however, an overlap will always be carried out over one needle only, while an underlap can be under several needles and could therefore require a larger rotation of the ring.the larger the number of rings, the greater the patterning possibilities. however,the amount of space to place t

31、hem and the complexity of the yarn paths generally restricts the number of patterning rings present in a machine.system requirementsthe first design prototype was used as an industrial knitting machine to produce packaging fabrics, stockings bandage materials and other technical textiles. a product

32、design specification for a machine to cover all these markets was carried out in order to establish the end products requirements. it was found that most applications would not require more than a 4-needle underlap. in addition, the minimum gauge (number of needles per inch) in the relevant applicat

33、ions was 4. the cylinder diameter is not critical for the netting applications; this varies in the range of 75100mm for the stockings application and it varies widely for medical applications. for the first prototype, a 75-mm diameter cylinder was used. for this size cylinder, four needle spaces at

34、four needles per inch are equivalent to 38 of the cylinder. a 4-needle underlap will probably require a rotation of 8 needle spaces, which is equivalent to 76.it was therefore decided to set as system requirement that the patterning mechanism must be able to perform a rotation of up to 80 in a singl

35、e underlap.the fabric designer can alter the portion of the knitting cycle allocated to the patterning ring movements (underlap and overlap). in the initial design of the circular warp-knitting machine, one-third of the machine cycle was deemed to be sucient for the needles movement. this leaves two

36、 thirds of the knitting cycle to perform the underlap and overlap; 120 each.assuming that the maximum speed of the machine is 1000 rpm, a single knitting cycle takes place in 60 ms. this leaves only 20 ms to perform the underlap and 20 ms for the overlap rotation.mechanical solutionthe patented patt

37、erning mechanisms 2,5 are all mechanically controlled, use two patterning rings controlled by open face cams and have a maximum pattern length of 12 machine cycles. the restriction on the number of cycles is due to space limitation.a larger number of machine cycles in a pattern would require a large

38、r cam, but the space in which the cam ts in is limited.the main progress achieved with the mechanical solution built as part of this research was: (1) the use of enclosed cam followers in the patterning cams, reducing shock and vibration eects created when using open face cams, (2) improvements of t

39、he manufacturing process of the patterning cams by developing a tailor-made tool to create the milling programs of the patterning cam, and (3) enhancement of the cam performance by using cycloidal proles for each segment. cycloidal profiles are known to give the best results for high-speed applicati

40、ons 3when compared to other basic displacement curves, because they provide three finite derivatives of displacement. the cycloidal displacement is given by:the only drawback to using this type of prole for the current application is the non-continuous jerk curve at the end points of each motion. th

41、at is, at the point where the rise (or return) period ends and the dwell period begins. this is because the third derivative of the displacement is not zero at the end point, whereas that of a dwell is. if necessary, the motion curves could be further optimised by using poly-nomial profiles to ensur

42、e that the displacement and its three derivatives are continuous throughout.a tailor-made computer application was developed to create the cam profile program, which is then downloaded into a nc milling machine. once on the knitting machine, the cam in motion was lmed using a high-speed video record

43、er (200 frames per second). there was no excessive vibration of the follower in the cam-track; even when viewed frame by frame it was seen that the follower did not leave the side of the track on which it was rolling.the mechanical system converts a translational motion created by the patterning cam

44、 into a rotation of the patterning ring by means of a number of pivots and mechanical linkages (see fig. 2). the conguration and length of the linkage components depend on the physical space available and the dimensions of the machine elements. for example, in order to create a longer pattern by cir

45、cular motion of the ring, while maintaining appropriate pressure angles in the cam, the baseline radius of the cam must increase.although the cam-follower mechanism ran smoothly, the high-speed video showed excessive vibration of the patterning rings. the contrast between the smooth running of the c

46、am follower and irregular motion of the rings suggests that the latter is created by the elasticity of the mechanical linkages. the speed of the machine would therefore always be constrained by the mechanical properties and the dimensions of the linkages.this mechanical design proved the circular wa

47、rp knitting mechanism concept to be feasible (see fig. 3). however, a design that allowed for more patterning exibility and ultimately higher operational speed was required in order to manufacture the more complex fabric designs used in the medical and stockings industries.servo-controlledsolutionan

48、 entirely new approach to the patterning mechanism problem was to control the rings using servomotors. although a more costly solution, it has the potential of creating pattern chains that are only restricted by the size of the memory of the hardware used (i.e.hundreds of machines cycles rather than

49、 12) and reducing the time and parts required to change from one pattern to another.in addition, a servomotor would produce a rotational motion, when coupled viatiming belts and pulleys could drive the patterning rings directly. there is no need for the mechanical transformation of translational mot

50、ion to a rotational one that would have been required if other electronically controlled linearly actuated mechanical devices were used, such as linear pneumatic actuators.servomotors were selected over stepper motors because of the speed of reaction and position control requirements given by the kn

51、itting application.this paper relates to the servo control of the patterning mechanism only. however, the main knitting mechanism, that is, the one responsible for the needle motion could also be servo-controlled giving further control over the synchronisation between needles and yarns. yao et al. 6

52、 propose a method to improve the motion characteristics of a cam follower by controlling the cam speed using servodrives.the design for warp knitting machine traversing control system based on dspabstract on the basis of studying warp knitting machine traversing control system in-depth,this paper de

53、signed a warp knitting machine traversing electronic control system based on digital signal processor (dsp). this system take a three-phase permanent magnet blushless linear dc motor (lpmbdcm) as main studying object and use dsp as the control center. thereby, it designed a practical electronic guid

54、e bar shogging mechanism. the emphases of this paper are explaining the hardware circuit and the system software, including linear motor driver, position detection, and speed current closed-loop detection and so on.keywords: warp knitting machine; traversing motion;linear motor; dsp; pwm; 1. introdu

55、ctionthe warp knitting industry is an important component of the textile industry, which is promoting the technology of manufacturing equipment of the warp knitting machine renovate. developing and researching a top grade intelligent warp knitting machine of high technology, high productivity, and h

56、igh reliability, the core technology needs a high precision shogging system of guide bar. because the shogging system of high precision could guarantee that guide needle can finish traversing during a shogging motion. accordingly, developing and studying an intelligent warp knitting machine of high

57、precision has extremely important practical significance.2 the existing control system of shogging motion of warp knitting machines2.1 the mechanical warp knitting machine shogging systemnowadays, the most using warp knitting machine is mechanical warp knitting machine in home. it made by different

58、dimension chain block arranged in vertical and horizontal chain belt, which control the patternitinerary to meet chlamys weaving pattern purposes when linked with the walking cycle. however, this machines disadvantage is every kind of pattern needing corresponding cam (or chain belt), which is high-cost. otherwise, producing and changing the patterns have become more and more difficult as the people requires patterns more and more high, and the number of