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1、附錄 英文原文： 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 k

2、ind 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

3、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

4、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 spl

5、it-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

6、 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 valu

7、e 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 cha

8、racteristic 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 outst

9、anding 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 c

10、ollection 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 lim

11、its, 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, geometr

12、y 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 i

13、nformation 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

14、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 th

15、e 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

16、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

17、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 compensat

18、es 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

19、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 sig

20、nal, 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 survey

21、s 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

22、 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 in

23、duction 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 el

24、ectricity 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

25、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 d

26、atabase 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 (

27、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

28、suppose Counts with the manufacture [ the regulation, 1,999, 28 (2): 12 ~ l4. 中文翻譯： 數(shù)控機床開環(huán)控制伺服系統(tǒng) 開環(huán)系統(tǒng)的優(yōu)點是系統(tǒng)簡單、成本低，但缺點是精度不高。反向間隙、絲杠螺距誤差、起停誤差等都會影響定位精度。下面幾種改進措施可以使定位精度明顯改善。 1 反向間隙誤差補償 數(shù)控機床加工刀具與工件的相對運動是依靠驅動裝置帶動齒輪、絲杠轉動，從而推動工作臺面等移動部件產(chǎn)生位移來實現(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，

29、當運動的方向改變時，開始段時間必然會引起驅動元件的空走，出現(xiàn)指令脈沖推不動執(zhí)行元件的局面。這就影響了機床的加工精度，即指令脈沖與實際進給步數(shù)不相符合，產(chǎn)生加工誤差 因此，開環(huán)數(shù)控系統(tǒng)一般都設置有反向間隙誤差補償功能，用以補足空走的步數(shù)反向間隙差補償就是首先實測反向進給的誤差，把它折算成脈沖當量數(shù)，作為間隙補償子程序的輸出量，當計算機判斷出現(xiàn)的指令為反向運動時，隨即調(diào)用間隙補償子程序，通過輸出補償脈沖消除反向間隙后再進行正常的插補運行。 2 常值系統(tǒng)性定位誤差補償 類庫以供設計者調(diào)用。這樣在零件的設計階段，設計者只需輸入特征的參數(shù)，系統(tǒng)直接生成特征的實例模型：在數(shù)據(jù)庫中我們必須存儲相

30、關的特征類的結構信息，數(shù)據(jù)庫表集就是用于存儲這一部分的相關信息。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；定義了特征類構造表表達特征類的結構；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)庫設計的核心，記錄了特征實例模型的設計、工藝等信息。特征構造表記錄了特征的幾何結構；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ID、粗糙度ID等主鍵進行數(shù)據(jù)檢索。我們將該零件信息模型的數(shù)據(jù)庫應用于工廠環(huán)

31、境下某型組件的CAD AM 集成系統(tǒng)中，較好地實現(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)進行產(chǎn)品設計和NC編程，并通過對該軟件進行二次開發(fā)獲取零件的尺寸信息；同時利用自行開發(fā)的對話窗體，讓設計人員交互輸入其它特征信息，實現(xiàn)該軟件與系統(tǒng)的共享數(shù)據(jù)庫的連接。在輔助工藝設計時，工藝設計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，進行交互工藝設計。從而方便了CAPP的零件信息獲取，提高了工藝設計的效率。在利用UG進行NC編程時，可以從共享數(shù)據(jù)庫中獲取所需的工藝及制造信息，進行各工序的刀軌設計與加工仿真在數(shù)控機床上建立

32、一個絕對零點，實測出各坐標軸相對點的全部定位誤差，做出曲線以便確定補償點。圖l所示是一個實測的定位誤差曲線，把這個曲線的縱坐標(誤差)以脈沖當量為單位進行分割，作出橫線，每個橫線與曲線的交點即為目標補償點。圖1中的1到6點處的定位誤差為正，需要作減脈沖補償；而6至9處需要進行加脈沖補償圖中陰影部分為補償區(qū)。把這些補償點列成誤差.修正表存入計算機，當工作臺由零點位置移動時，安裝在絕對原點處的微動開關發(fā)出絕對原點定位信號，以后計算機將隨時發(fā)出目標補償點的補償信號，對機床進行定位誤差補償。 3 反饋補償開環(huán)控制 該系統(tǒng)由開環(huán)控制和感應同步器直接位置測量兩個部分組成。這里的位置檢測不用作位

33、置的反饋，而是作為位置誤差的補償反饋。其基本的原理是：由機床數(shù)控裝置CNC發(fā)出的指令脈沖，一方面供給開環(huán)系統(tǒng)，控制步進電機按指令運轉，并直接驅動機床工作臺移動，構成開環(huán)控制；另一方面該指令脈沖又供給感應同步器的測量系統(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同步器此時既是位置檢測器，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電機。 4 結 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，怎樣提高特征設計所能完成的零件復雜度；如何使特征設計適應特征識別、特征語義轉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在零件信息建模中的應用，重點描述該零件數(shù)據(jù)模型的數(shù)據(jù)庫實現(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。