模具數(shù)控加工計(jì)算機(jī)輔助刀具選擇研究外文文獻(xiàn)翻譯@中英文翻譯@外文翻譯

1、<p><b>　　外文翻譯</b></p><p>　　專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 </p><p>　　學(xué) 生 姓 名 陳 曦 </p><p>　　班 級 BD機(jī)制031 </p><p>　　學(xué) 號

2、 0320110129 </p><p>　　指 導(dǎo) 教 師 劉 道 標(biāo) </p><p><b>　　.</b></p><p>　　模具數(shù)控加工計(jì)算機(jī)輔助刀具選擇研究</p><p><b>　　耿鐵</b></p><p&

3、gt;<b>　　段修濤譯</b></p><p><b>　　引言</b></p><p>　　數(shù)控加工中包括刀具軌跡的產(chǎn)生和刀具選擇兩個(gè)關(guān)鍵問題。前一問題在過去的20 年里得到了廣泛而深入地研究， 發(fā)展的許多算法已在商用CAD/ CAM 系統(tǒng)中得到應(yīng)用。目前大多數(shù)CAM 系統(tǒng)能夠在用戶輸入相關(guān)參數(shù)后自動(dòng)產(chǎn)生刀具軌跡。比較而言，對以質(zhì)量、效率為

4、優(yōu)化目標(biāo)的刀具選擇問題的研究還遠(yuǎn)未成熟，當(dāng)前還沒有商用CAM 系統(tǒng)能夠提供刀具優(yōu)選的決策支持工具，因而難以實(shí)現(xiàn)CAD/ CAM 的自動(dòng)有機(jī)集成。刀具選擇通常包括刀具類型和刀具尺寸。一般來說，適合一個(gè)加工對象的刀具通常有多種，一種刀具又可完成不同的加工任務(wù)，所以僅考慮滿足基本加工要求的刀具選擇是較容易的，尤其對孔、槽等典型幾何特征。但實(shí)際上，刀具選擇通常和一定的優(yōu)化目標(biāo)相聯(lián)系，如最大切削效率、最少加工時(shí)間、最低加工成本、最長使用壽命等，因

5、此刀具選擇又是一個(gè)復(fù)雜的優(yōu)化問題。比如模具型腔類零件，由于幾何形狀復(fù)雜(通常包含自由曲面及島) ，影響刀具選擇的幾何約束在CAD 模型中不能顯式表示，需要設(shè)計(jì)相應(yīng)的算法進(jìn)行提取，因而選擇合適的刀具規(guī)格及其刀具組合，以提高數(shù)控加工的效率與質(zhì)量并非易事。 </p><p>　　模具型腔一般用數(shù)控銑的加工方法，通常包括粗加工、半精加工、精加工等工序。粗加工的原則就是盡最大可能高效率地去除多余的金屬，因而希望選擇大尺寸的

6、刀具，但刀具尺寸過大，可能導(dǎo)致未加工體積的增多;半精加工的任務(wù)主要是去除粗加工遺留下來的臺(tái)階;精加工則主要保證零件的尺寸及表面質(zhì)量?？紤]到目前完全由計(jì)算機(jī)進(jìn)行自動(dòng)選刀還存在一定困難，因而在我們開發(fā)的計(jì)算機(jī)輔助刀具選擇(Computer Aided Tool Selection ，CATS)系統(tǒng)中，立足于給用戶提供一個(gè)輔助決策工具，即粗加工、半精加工、精加工等，真正的決策權(quán)仍留給用戶，以充分發(fā)揮計(jì)算機(jī)和人的優(yōu)勢。 </p>

7、<p><b>　　1 系統(tǒng)基本結(jié)構(gòu) </b></p><p>　　CATS系統(tǒng)的輸入為CAD模型，輸出為刀具類型、刀具規(guī)格、銑削深度、進(jìn)給量、主軸轉(zhuǎn)速(切削速度) 和加工時(shí)間等六個(gè)參數(shù)(如圖1) ，包括刀具類型選擇輔助決策工具、粗加工刀具選擇輔助決策工具、半精加工刀具選擇輔助決策工具及精加工刀具選擇輔助決策工具等。 </p><p>　　圖1 計(jì)算機(jī)輔助刀

8、具選擇系統(tǒng)的輸入與輸出</p><p>　　鑒于粗加工在型腔加工中的重要地位(通常為精加工時(shí)間的5～10 倍) ，粗加工時(shí)系統(tǒng)具有刀具自動(dòng)優(yōu)化組合的功能，以提高整體加工的效率。除了上述決策工具外，系統(tǒng)還具有查看刀具詳細(xì)規(guī)范、根據(jù)刀具類型和尺寸推薦加工參數(shù)及評估加工時(shí)間等功能，最后生成總的刀具選擇結(jié)果報(bào)表(如圖2) 。系統(tǒng)所有的刀具數(shù)據(jù)及知識(shí)均由后臺(tái)數(shù)據(jù)庫做支持。</p><p>　　圖2

9、計(jì)算機(jī)輔助刀具選擇系統(tǒng)的基本功能與模塊</p><p>　　2 關(guān)鍵技術(shù)及算法 </p><p><b>　　刀具類型選擇 </b></p><p>　　根據(jù)模具型腔數(shù)控加工實(shí)踐，型腔銑加工的刀具一般分為平頭銑刀、圓角銑刀及球頭銑刀三種。設(shè)刀具直徑為D，圓角半徑為r ，當(dāng)r=0 時(shí)為平頭銑刀，0<R刀具又可分為整體式和鑲片式。對于鑲片式，

10、關(guān)鍵是選取刀片的材質(zhì)，刀片材質(zhì)的選擇取決于三個(gè)要素：被加工工件的材料、機(jī)床夾具的穩(wěn)定性以及刀具的懸臂狀態(tài)。系統(tǒng)將被加工工件的材料分為鋼、不銹鋼、鑄鐵、有色金屬、難切削材料和硬材料等六組。機(jī)床夾具的穩(wěn)定性分為很好、好、不足三個(gè)等級。刀具懸臂分為短懸臂和長懸臂兩種，系統(tǒng)根據(jù)具體情況自動(dòng)推理出刀片材質(zhì)，決策知識(shí)來源于WALTER刀具手冊，系統(tǒng)由用戶首先交互選擇刀具類型。對鑲片式刀具，基于規(guī)則自動(dòng)推理出合適的刀片材質(zhì)。例如，如果被加工工件的材料

11、為“鋼”，機(jī)床夾具的穩(wěn)定性為很好，刀具懸臂為短懸臂，則刀片材質(zhì)應(yīng)為WAP25 。 </p><p>　　粗加工刀具組合優(yōu)化 </p><p>　　型腔粗加工的目的就是最大化地去除多余的金屬，通常使用平頭銑刀，采取層切的方法。因此，3D模具型腔的粗加工過程，實(shí)際上就是對一系列2.5D模具型腔的加工。刀具優(yōu)化的目的就是要尋找一組刀具組合，使其能夠以最高的效率切除最多的金屬。刀具組合優(yōu)化的基本方

12、法如下： </p><p>　　a.以一定的步長做一組垂直于進(jìn)刀方向的搜索平面與型腔實(shí)體相交，形成搜索層。 </p><p>　　b. 求出截交輪廓。 </p><p>　　c. 計(jì)算內(nèi)外環(huán)之間或島與島之間的關(guān)鍵距離，即影響刀具選擇的幾何約束，算法流程如圖3 所示。</p><p>　　圖3 求關(guān)鍵距離算法流程</p><

13、p>　　d. 根據(jù)合并原則(相鄰關(guān)鍵距離相差小于給定閾值) 對搜索層進(jìn)行合并，確定加工平面和可行刀具集，形成加工層。 </p><p>　　e. 確定每一加工層使用的刀具，即型腔加工的刀具組合。 </p><p>　　f. 根據(jù)刀具推薦的加工參數(shù)(切削速度、銑削深度和進(jìn)給速度) ，計(jì)算材料去除.</p><p>　　g. 根據(jù)加工層實(shí)際切除的體積，計(jì)算每一加工

14、層的加工時(shí)間。 </p><p>　　h. 計(jì)算型腔總的加工時(shí)間和殘余體積。 </p><p>　　i.對該組刀具組合的總體加工效率進(jìn)行評估。 </p><p>　　j. 重復(fù)a～i，直至求出最優(yōu)的刀具組合。如以時(shí)間為目標(biāo)，即要求以整個(gè)型腔的加工時(shí)間t 最短來優(yōu)化刀具組合?；谏鲜龇椒?，可建立如下形式化的優(yōu)化模型。</p><p>　　MRR

15、i=(dicij)×(Nfz)(切割截面積乘進(jìn)給率) </p><p>　　式中： n —型腔加工層數(shù)量; m —每一加工層刀具的銑削次數(shù); l —每一加工層中的搜索層數(shù)量; q —每一加工層可行的刀具數(shù)量; h —型腔深度; cij —i 加工層第j 次銑削深度; aj —第j 切割層底面積; vi —i 加工層的銑削體積;MRRi —i 加工層的材料去除率; di —i 加工層的刀具直徑; dip

16、 —i 加工層可行刀具集合; rik —i 加工層k 搜索層的關(guān)鍵距離;e1 —控制搜索層合并的常數(shù);e2 —控制殘余體積的常數(shù);V —型腔體積;DV —?dú)堄囿w積; N —主軸轉(zhuǎn)速; f —刀具每齒進(jìn)給量; z —刀具齒數(shù)?？紤]到不同的搜索平面步長會(huì)產(chǎn)生不同的加工層，從而導(dǎo)致不同的加工時(shí)間和殘余體積，因此有時(shí)盡管總的加工時(shí)間較短，但殘余體積可能較多。由此可見，單獨(dú)以加工時(shí)間為目標(biāo)進(jìn)行優(yōu)化有時(shí)并不一定科學(xué)。為此，提出了效率系數(shù)的概念，綜合

17、考慮了加工時(shí)間和殘余體積的因素，加工時(shí)間越短，殘余體積越少，則效率系數(shù)就越高。令：</p><p>　　上式中前一項(xiàng)反映了加工單位體積的時(shí)間系數(shù)，其中k =DV/V 為殘余體積百分?jǐn)?shù)。這樣，效率系數(shù)可定義為q = 1/ Q 。 </p><p><b>　　半精加工刀具選擇 </b></p><p>　　半精加工的主要目的是去除粗加工殘留下的臺(tái)

18、階狀輪廓。為完全去除臺(tái)階，銑削深度必須大于每一臺(tái)階到零件表面的距離x。其算法步驟如下： </p><p>　　步驟1 由零件實(shí)體模型獲得兩個(gè)相鄰截面的表面積以及相應(yīng)的輪廓長度; </p><p>　　步驟2 計(jì)算平均輪廓長度; </p><p>　　步驟3 計(jì)算臺(tái)階寬度; </p><p>　　步驟4 計(jì)算臺(tái)階拐角到零件表面的法向距離x ;

19、</p><p>　　步驟5 重復(fù)步驟1～步驟4 ，決定每一臺(tái)階的銑削深度; </p><p>　　步驟6 計(jì)算刀具直徑D， 按經(jīng)驗(yàn)D=x/0.6或根據(jù)刀具手冊推薦; </p><p>　　步驟7 選擇銑削深度大于x 的最小刀具。 </p><p><b>　　精加工刀具選擇 </b></p><p&

20、gt;　　精加工刀具選擇的基本原則是：刀具半徑尺寸R 小于零件表面最小的曲率半徑一般取R=(0.8～0.9)r。其算法步驟如下： </p><p>　　步驟1 從零件實(shí)體模型計(jì)算最小曲率半徑;</p><p>　　步驟2 從刀具庫中檢索出刀具半徑小于計(jì)算所得的曲率半徑的所有刀具;</p><p>　　步驟3 選出滿足上述要求的最大刀具; </p>&l

21、t;p>　　步驟4 如果所有刀具大于最小的曲率半徑，選擇最小的作為推薦刀具。 </p><p>　　3 系統(tǒng)實(shí)施及算例 </p><p>　　CATS 系統(tǒng)在UG/OPEN API環(huán)境下應(yīng)用C語言開發(fā)而成。后臺(tái)數(shù)據(jù)庫為Oracle 8i ，利用ODBC編程實(shí)現(xiàn)UG與數(shù)據(jù)庫之間的通訊。所有的刀具數(shù)據(jù)及知識(shí)來自德國WALTER 公司的硬質(zhì)合金刀具綜合樣本。圖4為一包含島及雕塑曲面的模具型

22、腔， 根據(jù)上文提出的粗加工刀具組合的優(yōu)化方法，該模具型腔粗加工刀具的優(yōu)化組合為20，12，8，5。計(jì)算中，工件材料選定為中碳鋼，切削速度推薦值為100m/min ，銑削深度為刀具直徑的1/ 2 ，進(jìn)給量根據(jù)刀具推薦值由程序自動(dòng)修正計(jì)算。同時(shí)，假定刀具庫中現(xiàn)有平頭銑刀刀具規(guī)格為f3，f4，f5，f6，f8，f10，f12，f16，f20。同樣，根據(jù)半精加工和精加工的刀具選擇算法，得到的球頭銑刀的刀具直徑分別為4和3。</p>

23、<p>　　圖4 包含島及雕塑曲面的模具型腔</p><p><b>　　4 小結(jié)與討論 </b></p><p>　　模具型腔加工的工藝規(guī)劃通常需要很高的技術(shù)與經(jīng)驗(yàn)，準(zhǔn)備NC 數(shù)據(jù)的時(shí)間幾乎和加工時(shí)間一樣多。因此，自動(dòng)產(chǎn)生型腔加工的工藝計(jì)劃及NC加工指令的需求就顯得愈加迫切。本文系統(tǒng)研究了模具型腔工藝規(guī)劃中的刀具選擇問題，提出了模具型腔粗加工、半精加工、

24、精加工刀具選擇的原則和方法，構(gòu)造了相應(yīng)的實(shí)現(xiàn)算法，并在UG/OPEN API環(huán)境下進(jìn)行了初步編程實(shí)現(xiàn)，開發(fā)了CATS原型系統(tǒng)。在刀具類型和規(guī)格確定的基礎(chǔ)上，系統(tǒng)還可根據(jù)刀具手冊推薦加工參數(shù)(切削速度、銑削深度、進(jìn)給量等) ，對相應(yīng)的加工時(shí)間進(jìn)行評估。其最終目的是真正實(shí)現(xiàn)CAD/CAM的集成，繼而通過后處理產(chǎn)生數(shù)控加工指令。目前CATS系統(tǒng)的界面還是獨(dú)立于UG的CAM界面，CATS的策結(jié)果還需要用戶重新輸入到CAM。需要指出的是，要提高模

25、具型腔的總體加工效率，需要從粗加工、半精加工、精加工的整體上考慮，進(jìn)行多目標(biāo)組合優(yōu)化，這將是我們下一步要進(jìn)行的工作。</p><p>　　Mould&Die NC computer-aided Tool of Selection </p><p><b>　　Geng Tie</b></p><p>　　State Key Lab.of

26、 Mould&Die Technology,HuaZhong University of Science and Technology </p><p>　　Wuhan 430074 ,China</p><p>　　Introduction</p><p>　　NC machining tool path generation and tool selec

27、tion, including the two key issues. Before a problem in the past 20 years has been wide-ranging and in-depth study, Many algorithms for the development of CAD ／ CAM system has been applied in the business. Most CAM syste

28、ms to the user input parameters with automatic tool path. Comparatively speaking, the quality, efficiency and optimization tool of choice is far from mature. Currently no commercial CAM system optimization tool can provi

29、de decision </p><p>　　NC general cavity with the processing methods, including extensive and usually, semi-finishing and finishing processes. Snag is the principle of maximum extent possible the efficient re

30、moval of excess metal and therefore wish to opt for large size of the tool, But cutter size is too large, might not lead to an increase in processing volume; the main task is getting extensive and semi-finished stage lef

31、t; finished the main components of the size and surface quality assurance. Taking into account </p><p>　　1.System structure.</p><p>　　CATS system for CAD model input, output types of tools, tool

32、 specifications Milling depth, feed, Spindle Speed (Speed) and the processing time of six parameters (Figure 1). Tool types of options, including decision-support tool, tool selection decision-support tool for roughing.

33、tool selection decision-support tool for semi-finishing and finishing tool selection decision-making tools.</p><p>　　Figure 1 computer-aided tool selection of input and output </p><p>　　Given ex

34、tensive and important position in the cavity (usually 5-10 times finishing time). snag when the system is automatically optimized combination of functional tool to enhance overall processing efficiency. In addition to th

35、e above decision-making tools, the system also has a detailed standardized tools to detect, According to the recommendation of processing parameters and the size and type of tool to assess the function of processing time

36、. Tool choice of the final total returns generated (</p><p>　　Figure 2 CAD tool selection and the basic function modules </p><p>　　2 key technology and algorithms </p><p>　　1) Tools

37、 for choice </p><p>　　According die NC practice, the tool generally consists of Milling Cutter peace. Fillet cutter and the cutter ball three. Based tool diameter D, the radius r, r = 0 when the crew cutter.

38、 0<R tools can be divided into the overall style and framed chip. Tipped for the ceremony, the key is to select material blades, blade materials are determined by three factors : the workpiece material, Machine tool f

39、ixture and the stability of the cantilever. Workpiece material will be processed into steel, stain</p><p>　　2) Portfolio Optimization Tool snag </p><p>　　The objective is to maximize the cavity

40、snag in the removal of excess metal, used Ping Cutter and take all the layers. Therefore, the 3D die roughing process is actually a series of 2.5D die for processing. Optimization Tool Tool Group's goal is to find a

41、combination that will enable it to the highest removal efficiency of most metals. The basic approach is as follows : Portfolio Optimization Tool </p><p>　　To do a certain step in the direction perpendicular

42、to the feed cavity search plane and entities intersect, the formation search layer. </p><p>　　Deadline for submission of outline obtained.</p><p>　　C. Calculation link between or outside of crit

43、ical distance between the islands, the choice of tools to influence the geometric constraint, the algorithm shown in figure 3.</p><p>　　Figure 3 key demand from the algorithm.</p><p>　　D. Under

44、this principle (the distance between adjacent key difference is less than a given threshold) level of the search for a merger Plane processing and identify viable tool sets, forming layers. </p><p>　　E. Each

45、 layer processing tool used to determine that the combination of the tool cavity. </p><p>　　F. According to the recommended processing tool parameters (cutting speed, feed rate and depth of milling), materia

46、l removal rate calculation. </p><p>　　G. According to the actual removal of the layer processing volume, the processing time is calculated for each layer processing. </p><p>　　H. Calculate the t

47、otal processing time and residual volume cavity. </p><p>　　I. The overall composition of this group processing efficiency assessment tool. </p><p>　　J. A~i repeated until the optimal combination

48、 of the tool. If time goal that the processing time t required for the entire cavity tool to optimize the combination of the shortest. Based on the above methodology, we can establish the following formal optimization mo

49、del. </p><p>　　MRRi=(dicij)×(Nfz) (X cross-sectional area of cutting feed rate)</p><p>　　Where : n-layer processing cavity volume; M-layer processing each of the milling cutter number; l-pr

50、ocessing layer in the search each layer volume; q-layer processing every tool possible number; h-cavity depth; cij -i time processing layer j Milling depth; aj - j cutting area of the base layer; vi -i processing volume

51、;MRRi -i milling layer, layer of material removal; di -i layer processing tool diameter; -i processing layer dip viable tool set; rik -i processing layer k ;e1 search of the key di</p><p>　　Plane taking into

52、 account the different steps in the search process will produce different levels, resulting in the processing time and residual volume, So sometimes, even though total processing time shorter, but more likely to residual

53、 volume. This shows that the target of a separate optimization of processing time are not necessarily science. Therefore, the coefficient of efficiency of the concept, considering the processing time and the residual vol

54、ume, the processing time is shorter. less r</p><p>　　On a middle-processing unit volume reflects the time factor, k =DV/V percentage of residual volume. Thus, the efficiency coefficient defined as q = 1/ Q.

55、</p><p>　　3) Semi-finished Tool Selection </p><p>　　The main purpose is to remove semi-finished roughing the residue level contour shape. For the complete removal of height, depth milling the su

56、rface must be greater than the distance between each level of x components. Algorithm steps are as follows :</p><p>　　Step 1 model will have two parts from the adjacent section and the corresponding surface

57、contour length; </p><p>　　Step 2 calculation of the average length profile; </p><p>　　Step 3 calculating height width; </p><p>　　Step 4 Calculation of the corner to level the surfac

58、e of the parts to distance x law;</p><p>　　Step 5 Repeat steps from 1 to 4 steps, each step of the decision Milling depth; </p><p>　　Step 6 curve of the diameter D, D=x/0.6 Tools manual or recom

59、mended by experience; </p><p>　　Step 7 x greater than the minimum depth of choice milling cutter.</p><p>　　4) finished Tool Selection </p><p>　　The basic principle is : finishing to

60、ol selection tool radius R size smaller than the smallest curvature radius r surface parts. General admission R = (0.8~0.9) r. The following steps :</p><p>　　Step 1 algorithm model from the smallest radius o

61、f curvature parts entities; Step 2 retrieved from the database tool cutter radius less than the radius of curvature calculation for all tool; </p><p>　　Step 3 select the best tools to meet these requirements

62、; </p><p>　　Step 4 : If all the tools than the smallest radius of curvature. Minimum recommended as a tool of choice. </p><p>　　3 implementation of the system and examples </p><p>　

63、　CATS system in the C language environment UG/OPEN API was developed. Background for the Oracle 8i database using ODBC programming and database communications between UG. All the data and knowledge from Germany WALTER To

64、ol Company Carbide Tool integrated samples.Figure 4 contains a sculptured surface of the mold cavity and the island, according to the snag in the portfolio optimization tool, The die-extensive portfolio optimization tool

65、 for 20,12,8,5. Calculation, the workpiece material selected </p><p>　　Figure 4 contains the island and sculptured surface of the mold cavity </p><p>　　4 Summary and Discussion </p><p

66、>　　The planning process usually die of high technology and experience NC data preparation and processing almost as much time. Therefore, the automatic process planning cavity NC machining instructions and it is even m

67、ore urgent needs. We systematically studied the tool selection process planning die, the die roughing, semi-finishing. and finishing tool of choice for the method, the corresponding algorithm. UG/OPEN environment in a pr