數控類外文文獻翻譯--模具型腔數控加工計算機輔助刀具選擇和研究

1、<p>　　Mould type of numerical control process computer assist the cutter choose and study</p><p><b>　　Foreword</b></p><p>　　Numerical control include cutter production and cutte

2、r of orbit choose two key problems process ,. The first problem has been got and studied extensivly and deeply over the past 20 years, a lot of algorithms developed have already got application in commercial CAD/ CAM sys

3、tem. Most CAM systems can produce the cutter orbit automatically after users input relevant parameters at present. Comparatively speaking , it is still not ripe to regard quality , efficiency as the research of choosing

4、the pro</p><p>　　Mould type generally with preparation method that numerical control mill, usually including rough machining, half finish machining , precise process of processing etc.. The principle of roug

5、h machining is to spare no effort to remove the surplus metal with high efficiency, therefore hope to choose the larger cutter, but the cutter is oversized, may cause the increase of the crude volume ; Half finish machin

6、ing of tasks to remove rough machining leave over step that get off mainly; Finish machini</p><p>　　1 Basic structure of the system </p><p>　　CATS system is CAD model, output for cutter type ,

7、cutter specification , mill depth of sharpening , enter the giving amount , rotational speed of main shaft (cut the pace ) and process six parameters such as time (such as Fig. 1), including choosing the aid decision too

8、l in cutter type, rough machining cutter choose aid decision tool, half finish machining cutter choose aid decision tool and finish machining cutter choose aid decision tool ,etc.</p><p>　　Given the rough ma

9、chining in Xingqiang processing of the important position (usually rely time 5~10 times), rough machining, the system automatically optimize portfolio with cutlery functions to enhance overall processing efficiency. In a

10、ddition to the decision-making tools, the system also has a detailed look cutlery norms, based on the type and size cutlery recommended processing parameters and assess the function of processing time, the last generatio

11、n of the overall results of choice cutlery</p><p>　　Key technologies and algorithms</p><p>　　Cutlery type choice</p><p>　　According to Assistant Xingqiang digital processing practic

12、e, Xingqiang Xi state general processing cutlery into milling cutter, milling cutter radius milling cutter and the first three balls. D based cutlery diameter, radius radius r when r=0 for milling cutter, 0<R</p>

13、;<p>　　Cutlery can be divided into the overall style and embed films ceremony. For inlay film style, the key is to select the materials razor blades, razor blades materials choice depends on three elements : the p

14、rocessing of working materials, machine tools and cutlery jig stability of the state structures. Processing system will be translated into material steel, stainless steel, cast iron, nonferrous metals, materials and hard

15、 to cut materials six groups. Machine tool jig stability into good, better</p><p>　　Rough machining cutlery portfolio optimization</p><p>　　Xingqiang rough machining the aim is to maximize the r

16、emoval of excess metal normally used milling cutter, take-cutting approach. Thus, 3D mould Xingqiang the rough machining process, is actually a series of 2.5D components Xingqiang processing. Cutlery optimization is to f

17、ind a group of cutlery portfolio, allowing for maximum efficiency removal of most metals. Cutlery portfolio optimized basic methods as follows :</p><p>　　To do some long step into knife in the direction of a

18、 group of vertical and horizontal search Xingqiang another entity to form a search layer.</p><p>　　Derive closed to the contours.</p><p>　　Calculated between Central and outside the island or is

19、lands and the distance between the key that affect cutlery choice geometric constraints algorithm flow As shown in figure 3</p><p>　　According to the principle of the merger (adjacent to the critical distanc

20、e will be smaller than the difference between the threshold) to search layer merger, graphic processing and identifying viable cutlery sets, a processing layer.</p><p>　　Determine the use of each processing

21、layer cutlery, cutlery Xingqiang processing portfolio. </p><p>　　According cutlery recommended processing parameters (cutting speed, depth and into Xianxiao to speed), the calculation of material removal. &l

22、t;/p><p>　　According to the actual removal of the volume processing layer, the processing time for each processing layer. </p><p>　　Xingqiang calculating the total processing time and residual volu

23、me.</p><p>　　The overall portfolio of the Group cutlery processing efficiency assessment. </p><p>　　J . Repeat a~i until derive optimal mix of cutlery. If time is the goal, called for the entir

24、e processing time t Xingqiang shortest portfolio to optimize cutlery.</p><p>　　Semi-finished cutlery choice</p><p>　　The main purpose is to remove semi-finished rough machining residual contours

25、 of the new warrants. To completely remove height, depth must be greater than Xianxiao parts of each level to the surface distance x. Its algorithm steps are as follows :</p><p>　　Step 1:entity models from p

26、arts of two adjacent to the cross section of the surface contours and the corresponding length;</p><p>　　Step 2: The average length of contours;</p><p>　　Step 3:calculate its width;</p>&

27、lt;p>　　Step 4 : calculating height floor to the surface of parts to the law distance x;</p><p>　　Step 5 : steps 1~ repeat steps 4, each level of decision Xianxiao depth;</p><p>　　Step 6 : cal

28、culate cutlery diameter D, by or under cutlery experience D=x/0.6 manual recommended;</p><p>　　steps7 : choose Xianxiao x depth than the smallest cutlery.</p><p>　　fine cutlery choice</p>

29、<p>　　Fine cutlery choice is the basic principle : cutlery parts surface radius smaller than the smallest size R curve radius r, the general admission R= (0.8~0.9) r. Its algorithm steps are as follows :</p>

30、<p>　　Step 1 : from the smallest curve radius calculation model parts entities; </p><p>　　Step 2 : From cutlery database search radius of less than a cutlery calculated radius of the curve all cutlery;

31、 </p><p>　　Step 3 : select the best cutlery meet the above requirements; </p><p>　　Step 4 : If all cutlery than the smallest curve radius, the smallest chosen as a recommended cutlery.</p>

32、<p>　　3 summary and discussion</p><p>　　Mould type of craft of processing plan , need high technology and experience very usually, prepare NC time of data nearly and process time to be large. So pers

33、on who produce of craft of processing plan and NC process demand of the order right away seem further more urgent automatically.</p><p>　　This text system research mould type of craft cutter plan , choose pr

34、oblem, put forward mould of rough machining , half finish machining , finish machining principle and method that cutter chooses, the realization algorithm with corresponding structure , and has carried on the realization

35、 of preliminary programming under the environment of UG/OPEN API, have developed CATS prototype system. In cutter type and on the foundation that the specification is fixed, system also can recommend parameter o</p>

36、;<p>　　Need to point out , should improve the mould type totality of and process efficiency, need it from the rough machining , half finish machining , consideration on the whole of finish machining , make up and

37、optimize many targets, this will be work that we want to carry on next .</p><p>　　模具型腔數控加工計算機輔助刀具選擇和研究</p><p>　　引言 數控加工中包括刀具軌跡的產生和刀具選擇兩個關鍵問題。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)

38、中得到應用。目前大多數CAM 系統(tǒng)能夠在用戶輸入相關參數后自動產生刀具軌跡。比較而言，對以質量、效率為優(yōu)化目標的刀具選擇問題的研究還遠未成熟，當前還沒有商用CAM 系統(tǒng)能夠提供刀具優(yōu)選的決策支持工具，因而難以實現CAD/ CAM 的自動有機集成。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，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。但實際

39、上，刀具選擇通常和一定的優(yōu)化目標相聯(lián)系，如最大切削效率、最少加工時間、最低加工成本、最長使用壽命等，因此刀具選擇又是一個復雜的優(yōu)化問題。比如模具型腔類零件，由于幾何形狀復雜(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，需要設計相應的算法進行提取，因而選擇合適的刀具規(guī)格及其刀具組合，以提高數控加工的效率與質量并非易事。 模具型腔一般用數控銑的加工方法，</p><p>　

40、　鑒于粗加工在型腔加工中的重要地位(通常為精加工時間的5～10 倍) ，粗加工時系統(tǒng)具有刀具自動優(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規(guī)范、根據刀具類型和尺寸推薦加工參數及評估加工時間等功能，最后生成總的刀具選擇結果報表。系統(tǒng)所有的刀具數據及知識均由后臺數據庫做支持。 </p><p>　　2 關鍵技術及算法 2.1 刀具類型選擇 根據模具型腔數控加工實踐，型

41、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。設刀具直徑為D，圓角半徑為r ，當r=0 時為平頭銑刀，0<R 刀具又可分為整體式和鑲片式。對于鑲片式，關鍵是選取刀片的材質，刀片材質的選擇取決于三個要素：被加工工件的材料、機床夾具的穩(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。機床夾具的穩(wěn)定性分為很好、好、不足三個等級。刀具懸臂分為短懸臂和長懸臂兩種，系統(tǒng)

42、根據具體情況自動推理出刀片材質，決策知識來源于</p><p>　　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)則自動推理出合適的刀片材質。例如，如果被加工工件的材料為“鋼”，機床夾具的穩(wěn)定性為很好，刀具懸臂為短懸臂，則刀片材質應為WAP25 。 粗加工刀具組合優(yōu)化 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

43、過程，實際上就是對一系列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)化的基本方法如下： A. 以一定的步長做一組垂直于進刀方向的搜索平面與型腔實體相交，形成若干搜索層。 B. 求出截交輪廓。 C. 計算內外環(huán)之間或島與島之間的關鍵距離，即影響刀具選擇的幾何約束. </p><p>　　D. 根據合并原則(相鄰關鍵距離相差小于給定閾值) 對搜索層

44、進行合并，確定加工平面和可行刀具集，形成加工層。 E. 確定每一加工層使用的刀具，即型腔加工的刀具組合。 F. 根據刀具推薦的加工參數(切削速度、銑削深度和進給速度) ，計算材料去除率。 G. 根據加工層實際切除的體積，計算每一加工層的加工時間。 H. 計算型腔總的加工時間和殘余體積。 I. 對該組刀具組合的總體加工效率進行評估。 J. 重復a～i，直至求出最優(yōu)的刀具組合。如以時間為目標，即要求以整個型腔的加工時間t 最短來

45、優(yōu)化刀具組合。 </p><p>　　2.2半精加工刀具選擇 半精加工的主要目的是去除粗加工殘留下的臺階狀輪廓。為完全去除臺階，銑削深度必須大于每一臺階到零件表面的距離x。其算法步驟如下： 步驟1 由零件實體模型獲得兩個相鄰截面的表面積以及相應的輪廓長度; 步驟2 計算平均輪廓長度; 步驟3 計算臺階寬度; 步驟4 計算臺階拐角到零件表面的法向距離x ; 步驟5 重復步驟1～步驟4 ，決定每一臺階的銑

46、削深度; 步驟6 計算刀具直徑D， 按經驗D=x/0.6或根據刀具手冊推薦; 步驟7 選擇銑削深度大于x 的最小刀具。 </p><p>　　2.3 精加工刀具選擇 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r，一般取R=(0.8～0.9)r。其算法步驟如下： 步驟1: 從零件實體模型計算最小曲率半徑; 步驟2: 從刀具庫中檢索出刀具半徑小于計算所得的曲率半徑的所有刀具;

47、步驟3: 選出滿足上述要求的最大刀具; 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 小結與討論 模具型腔加工的工藝規(guī)劃通常需要很高的技術與經驗，準備NC 數據的時間幾乎和加工時間一樣多。因此，自動產生型腔加工的工藝計劃及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、精加工

48、刀具選擇的原則和方法，構造了相應的實現算法，并在UG/OPEN API環(huán)境下進行了初步編程實現，開發(fā)了CATS原型系統(tǒng)。在刀具類型和規(guī)格確定的基礎上，系統(tǒng)還可根據刀具手冊推薦加工參數(切削速度、銑削深度、進給量等) ，對相應的加工時間進行評估。其最終目的是真正實現CAD/CAM的集成，繼而通過后處理產生數控加工指令。目前CATS系統(tǒng)的界面還是獨立于UG的CAM界面，CATS的決策結果還需要用戶重新輸入到CAM。 需要指出的是，