【機(jī)械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】數(shù)控機(jī)床開環(huán)控制伺服系統(tǒng)
【機(jī)械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】數(shù)控機(jī)床開環(huán)控制伺服系統(tǒng),機(jī)械類畢業(yè)論文中英文對照文獻(xiàn)翻譯,機(jī)械類,畢業(yè)論文,中英文,對照,對比,比照,文獻(xiàn),翻譯,數(shù)控機(jī)床,開環(huán),控制,節(jié)制,伺服系統(tǒng)
The open system merit of Computer Numerical Control
The open system merit is the system simple, the cost low, but the shortcoming is the precision is low. The reverse gap, the guide screw pitch error, stop inferiorly can affect the pointing accuracy by mistake. Following several kind of improvements measure may cause the pointing accuracy distinct improvement.
1. reverse gap error compensates
The numerical control engine bed processing cutting tool and the work piece relative motion is depends upon the drive impetus gear,the guide screw rotation, thus the impetus work floor and so on moves the part to produce moves realizes. As traditional part gear, guide screw although the manufacture precision is very high, but always unavoidably has the gap. As a result of this kind of gap existence, when movement direction change, starts the section time to be able to cause inevitably actuates the part wasting time, appears the instruction pulse to push the motionless functional element the aspect. This has affected the engine bed processing precision, namely the instruction pulse and actual enters for the step does not tally,has the processing error therefore, the split-ring numerical control system all establishes generally has the reverse gap error compensatory function, with by makes up which wastes time the step reverse gap difference compensates is first actual reverse enters for the error, converts the pulse equivalent number it, compensates the subroutine as the gap the output, when the computer judgment appears when instruction for counter motion, transfers the gap to compensate the subroutine immediately, compensates the pulse after the output to eliminate the reverse gap to carry on again normally inserts makes up the movement.
2. often the value systematic characteristic position error compensates
A kind of storehouse by transfers for the designer. Like this in the components design stage, the designer only must input the characteristic the parameter, the system direct production characteristic example model: We must save the related characteristic class in the database the structure information, the database table collection are use in saving this part of related information. According to the characteristic type definition need, we defined the characteristic class code table, the characteristic class edition information have outstanding shown the characteristic type; Defined the characteristic class structure outstanding to reach the characteristic class the structure; And relates through the components characteristic disposition table and the components characteristic level information. The characteristic level data sheet collection is this components model database design core, has recorded characteristic example information and so on model design, craft. The characteristic structure table has recorded the characteristic geometry structure; The characteristic size table, the characteristic shape position table of limits, the characteristic surface roughness table has recorded the characteristic project semantics quotation; The size table, the shape position table of limits, the surface roughness table saved all components characteristic data message. In the characteristic level, using characteristic ID, geometry principal linkage and so on essential factor ID, size ID, common difference ID, roughness ID carries on the data retrieval. We apply this components information model database under the factory environment some module CAD in the AM integrative system, has realized CAD and the CAPP characteristic information sharing well. Main use ready-made CAD/the CAM software (Unigra phics 1I) carries on the product design and the NC programming in this system, and through carries on two times of developments gains components to this software the size information; At the same time uses the dialogue window which develops voluntarily, lets design the personnel to input other characteristic information alternately, realizes this software and the system sharing database connection. When assistance technological design, the technological design personnel through the procedure inquiry function, inquires the components information from the sharing database which needs, carries on the interactive technological design. Thus has facilitated the CAPP components information acquisition, enhanced the technological design efficiency. When carries on the NC programming using UG, may from the sharing database gain the craft and the manufacture information which needs, carries on various working procedures the knife axle design and the processing simulation establishes an absolute zero spot on the numerical control engine bed, the actual various coordinate axes syzygy completely position error, makes the curve in order to determined compensates the spot. Attempts l to show is an actual position error curve, (error) carries on this curve y-coordinate take the pulse equivalent as the unit the division, makes the horizontal line, each horizontal line and the curve point of intersection namely compensates the spot for the goal. Chart 1 the center 1 to 6 o'clock place position errors for, needs to do reduces the pulse to compensate; But needs to carry on 6 to 9 adds the pulse to compensate in the chart the shadow partially for to compensate the area. Compensates the range of points these to become the error
The calibration corrections stores the computer, when work table by zero displacement in position, installs sends out the absolute zero point localization signal in the absolute zero point micros witch, later computer as necessary will send out the goal to compensate to compensate the signal, will carry on the position error to the engine bed to compensate. The cosine generator assigns slide guage initiation signal a electricity and by step of transmission.
3. feedbacks compensates the open-loop control
Chart 2 has produced this kind of system schematic diagram. This system surveys two parts by the open-loop control and the induction synchromesh direct position to be composed. Here position examination does not serve as the position the feedback, but is compensates the feedback as the position error. Its cardinal principle is: Installs the instruction pulse by the engine bed numerical control which CNC sends out, on the one hand the supplies open system, the control step-by-steps the electrical machinery according to the instruction revolution, and the direct drive platen moves, constitutes the open-loop control; On the other hand this instruction pulse supplies the induction synchromesh the measurement system (namely digitally, cosine generator), as position demand signal a by. The work in the warning way induction synchromesh this time not only is the position sensor, also is the comparator, it by, The cosine generator assigns slide guage initiation signal a electricity and by step of transmission.
4. conclusions
Under the CIMS environment the technology which develops unceasingly based on characteristic components information modeling, how enhances the components order of complexity which the characteristic design can complete; How causes question and so on request which the characteristic design adoption trick recognition, the characteristic semantics transforms also to wait for the people to solve. This article introduced the characteristic technology in the components information modeling application, describes this components data model database realization with emphasis; Establishes the components information database system may satisfy the CIMS system well to the letter.
Reference:
[1].Zhang Huashu under. parallel environment based on characteristic components definition model [J]. mechanical science with technology, 1,999, 18 (1): 14l 144.
[2].forest morning star, Du full text, Xu Jianxin. characteristic and (',M)/CAPP/CAM integrative system [J]. the computer-aided design and makes, 1998, 28 (5): 5155.
[3].Zeng Hui E, Zhou Qingzhong. studied J based on the characteristic mechanical product modelling ]. the machinery to suppose Counts with the manufacture [ the regulation, 1,999, 28 (2): 12 ~ l4.
數(shù)控機(jī)床開環(huán)控制伺服系統(tǒng)
開環(huán)系統(tǒng)的優(yōu)點(diǎn)是系統(tǒng)簡單、成本低，但缺點(diǎn)是精度不高。反向間隙、絲杠螺距誤差、起停誤差等都會(huì)影響定位精度。下面幾種改進(jìn)措施可以使定位精度明顯改善。
1 反向間隙誤差補(bǔ)償
數(shù)控機(jī)床加工刀具與工件的相對運(yùn)動(dòng)是依靠驅(qū)動(dòng)裝置帶動(dòng)齒輪、絲杠轉(zhuǎn)動(dòng)，從而推動(dòng)工作臺(tái)面等移動(dòng)部件產(chǎn)生位移來實(shí)現(xiàn)的。作為傳統(tǒng)元件的齒輪、絲杠盡管制造精度很高，但總免不了存在間隙。由于這種間隙存在，當(dāng)運(yùn)動(dòng)的方向改變時(shí)，開始段時(shí)間必然會(huì)引起驅(qū)動(dòng)元件的空走，出現(xiàn)指令脈沖推不動(dòng)執(zhí)行元件的局面。這就影響了機(jī)床的加工精度，即指令脈沖與實(shí)際進(jìn)給步數(shù)不相符合，產(chǎn)生加工誤差 因此，開環(huán)數(shù)控系統(tǒng)一般都設(shè)置有反向間隙誤差補(bǔ)償功能，用以補(bǔ)足空走的步數(shù)反向間隙差補(bǔ)償就是首先實(shí)測反向進(jìn)給的誤差，把它折算成脈沖當(dāng)量數(shù)，作為間隙補(bǔ)償子程序的輸出量，當(dāng)計(jì)算機(jī)判斷出現(xiàn)的指令為反向運(yùn)動(dòng)時(shí)，隨即調(diào)用間隙補(bǔ)償子程序，通過輸出補(bǔ)償脈沖消除反向間隙后再進(jìn)行正常的插補(bǔ)運(yùn)行。
2 常值系統(tǒng)性定位誤差補(bǔ)償
類庫以供設(shè)計(jì)者調(diào)用。這樣在零件的設(shè)計(jì)階段，設(shè)計(jì)者只需輸入特征的參數(shù)，系統(tǒng)直接生成特征的實(shí)例模型：在數(shù)據(jù)庫中我們必須存儲(chǔ)相關(guān)的特征類的結(jié)構(gòu)信息，數(shù)據(jù)庫表集就是用于存儲(chǔ)這一部分的相關(guān)信息。根據(jù)特征類型定義的需要，我們定義了特征類編碼表、特征類版本信息表表示特征類型；定義了特征類構(gòu)造表表達(dá)特征類的結(jié)構(gòu)；并通過零件特征配置表與零件的特征層信息聯(lián)系起來。特征層數(shù)據(jù)表集是本零件模型數(shù)據(jù)庫設(shè)計(jì)的核心，記錄了特征實(shí)例模型的設(shè)計(jì)、工藝等信息。特征構(gòu)造表記錄了特征的幾何結(jié)構(gòu)；特征尺寸表、特征形位公差表、特征表面粗糙度表記錄了特征的工程語義引用；尺寸表、形位公差表、表面粗糙度表存儲(chǔ)了所有零件特征的數(shù)據(jù)信息。在特征層，利用特征ID、幾何要素ID、尺寸ID、公差I(lǐng)D、粗糙度ID等主鍵進(jìn)行數(shù)據(jù)檢索。我們將該零件信息模型的數(shù)據(jù)庫應(yīng)用于工廠環(huán)境下某型組件的CAD AM 集成系統(tǒng)中，較好地實(shí)現(xiàn)了CAD與CAPP的特征信息共享。在該系統(tǒng)中主要使用現(xiàn)成的CAD／CAM 軟件(Unigraphics 1I)進(jìn)行產(chǎn)品設(shè)計(jì)和NC編程，并通過對該軟件進(jìn)行二次開發(fā)獲取零件的尺寸信息；同時(shí)利用自行開發(fā)的對話窗體，讓設(shè)計(jì)人員交互輸入其它特征信息，實(shí)現(xiàn)該軟件與系統(tǒng)的共享數(shù)據(jù)庫的連接。在輔助工藝設(shè)計(jì)時(shí)，工藝設(shè)計(jì)人員通過程序的查詢功能，從共享數(shù)據(jù)庫中查詢所需的零件信息，進(jìn)行交互工藝設(shè)計(jì)。從而方便了CAPP的零件信息獲取，提高了工藝設(shè)計(jì)的效率。在利用UG進(jìn)行NC編程時(shí)，可以從共享數(shù)據(jù)庫中獲取所需的工藝及制造信息，進(jìn)行各工序的刀軌設(shè)計(jì)與加工仿真在數(shù)控機(jī)床上建立一個(gè)絕對零點(diǎn)，實(shí)測出各坐標(biāo)軸相對點(diǎn)的全部定位誤差，做出曲線以便確定補(bǔ)償點(diǎn)。圖l所示是一個(gè)實(shí)測的定位誤差曲線，把這個(gè)曲線的縱坐標(biāo)(誤差)以脈沖當(dāng)量為單位進(jìn)行分割，作出橫線，每個(gè)橫線與曲線的交點(diǎn)即為目標(biāo)補(bǔ)償點(diǎn)。圖1中的1到6點(diǎn)處的定位誤差為正，需要作減脈沖補(bǔ)償；而6至9處需要進(jìn)行加脈沖補(bǔ)償圖中陰影部分為補(bǔ)償區(qū)。把這些補(bǔ)償點(diǎn)列成誤差.修正表存入計(jì)算機(jī)，當(dāng)工作臺(tái)由零點(diǎn)位置移動(dòng)時(shí)，安裝在絕對原點(diǎn)處的微動(dòng)開關(guān)發(fā)出絕對原點(diǎn)定位信號，以后計(jì)算機(jī)將隨時(shí)發(fā)出目標(biāo)補(bǔ)償點(diǎn)的補(bǔ)償信號，對機(jī)床進(jìn)行定位誤差補(bǔ)償。
3 反饋補(bǔ)償開環(huán)控制
該系統(tǒng)由開環(huán)控制和感應(yīng)同步器直接位置測量兩個(gè)部分組成。這里的位置檢測不用作位置的反饋，而是作為位置誤差的補(bǔ)償反饋。其基本的原理是：由機(jī)床數(shù)控裝置CNC發(fā)出的指令脈沖，一方面供給開環(huán)系統(tǒng)，控制步進(jìn)電機(jī)按指令運(yùn)轉(zhuǎn)，并直接驅(qū)動(dòng)機(jī)床工作臺(tái)移動(dòng)，構(gòu)成開環(huán)控制；另一方面該指令脈沖又供給感應(yīng)同步器的測量系統(tǒng)(即數(shù)字式正、余弦發(fā)生器)，作為位置給定信號。工作在鑒幅方式的感應(yīng)同步器此時(shí)既是位置檢測器，又是比較器，它把由正、余弦發(fā)生器給定的滑尺激磁信號傳送給步進(jìn)電機(jī)。
4 結(jié) 論
CIMS環(huán)境下基于特征的零件信息建模還是一門不斷發(fā)展的技術(shù)，怎樣提高特征設(shè)計(jì)所能完成的零件復(fù)雜度；如何使特征設(shè)計(jì)適應(yīng)特征識(shí)別、特征語義轉(zhuǎn)換的要求等問題還有待人們?nèi)ソ鉀Q。本文介紹了特征技術(shù)在零件信息建模中的應(yīng)用，重點(diǎn)描述該零件數(shù)據(jù)模型的數(shù)據(jù)庫實(shí)現(xiàn)；所建立的零件信息數(shù)據(jù)庫系統(tǒng)可以較好地滿足CIMS系統(tǒng)對信。
參考文獻(xiàn)：
[1]. 張華書．并行環(huán)境下基于特征的零件定義模型 [J]．機(jī)械科學(xué)與技術(shù)，1999，18(1)：14l 144．
[2]. 林曉星，杜全文，許建新．特征與(M)／CAPP／CAM 集成系統(tǒng) [J]．計(jì)算機(jī)輔助設(shè)計(jì)與制造，1998，28(5)：51 55．
[3]. 曾慧娥，周慶忠．基于特征的機(jī)械產(chǎn)品造型研究 [J]．機(jī)械設(shè)計(jì)與制造 [程，1999，28(2)：1 2～l4．
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