CAD／CAM技術(shù)及應(yīng)用

1、試題：（注：一、二、三、四題為必做題，五、六題選做其中一題，請(qǐng)?jiān)诖痤}紙中寫(xiě)清題號(hào)。）一、以一個(gè)你熟悉的實(shí)際機(jī)械產(chǎn)品（或零件、部件）為例，進(jìn)行如下分析說(shuō)明：1)分析該產(chǎn)品的設(shè)計(jì)與制造由哪些具體環(huán)節(jié)（過(guò)程）組成（要求繪出產(chǎn)品生產(chǎn)過(guò)程的流程圖，并進(jìn)行文字說(shuō)明）。（10分）答：齒輪傳動(dòng)是機(jī)械傳動(dòng)中最重要的傳動(dòng)之一，形式很多，應(yīng)用廣泛，傳遞功率可達(dá)近十萬(wàn)千瓦，其主要特點(diǎn)：效率高、結(jié)構(gòu)緊湊、工作可靠，壽命長(zhǎng)、傳動(dòng)比穩(wěn)定。 設(shè)計(jì)的環(huán)節(jié)包括：齒輪模數(shù)和壓力角的選擇，齒輪齒數(shù)的設(shè)計(jì)，齒輪幾何尺寸計(jì)算，強(qiáng)度的計(jì)算和校核，齒輪結(jié)構(gòu)的設(shè)計(jì)，齒輪精度的設(shè)計(jì)。 制造的環(huán)節(jié)包括：下料鍛造預(yù)先熱處理粗加工最終熱處理精加工。2

2、)以你熟悉的CAD/CAM軟件系統(tǒng)(如UG)為例，具體分析說(shuō)明怎樣利用該軟件系統(tǒng)輔助完成該產(chǎn)品的哪些設(shè)計(jì)和制造工作。（20分）答：設(shè)計(jì)環(huán)節(jié)可以采用CAD、CAE單項(xiàng)技術(shù)，制造可以采用CAPP、CAM單項(xiàng)技術(shù)。 CAD系統(tǒng)解決幾何建模、工程分析、模擬仿真、工程繪圖等主要功能；CAE（Computer Aided Engineering）是用計(jì)算機(jī)輔助求解產(chǎn)品結(jié)構(gòu)強(qiáng)度、剛度、屈曲穩(wěn)定性、動(dòng)力響應(yīng)、熱傳導(dǎo)、三維多體接觸、彈塑性等力學(xué)性能的分析計(jì)算以及結(jié)構(gòu)性能的優(yōu)化設(shè)計(jì)。CAPP系統(tǒng)的解決毛坯設(shè)計(jì)、加工方法選擇、工序設(shè)計(jì)、工藝路線制定和工時(shí)定額計(jì)算等。CAM解決零件造型和加工。二、具體分析說(shuō)明有限元分

3、析包括哪三個(gè)主要階段？在每個(gè)階段各解決哪些問(wèn)題？（10分）答：有限元分析過(guò)程可以分為以下三個(gè)階段：    1.建模階段2.計(jì)算階段  3.后處理階段三、某零件的三視圖和立體圖如下所示。(1)分析指出該零件由哪些形狀特征組成(繪簡(jiǎn)圖說(shuō)明)。（10分）(2)簡(jiǎn)述用UG實(shí)現(xiàn)下圖所示零件三維造型的步驟(分步驟進(jìn)行文字說(shuō)明,并配適當(dāng)?shù)暮?jiǎn)圖說(shuō)明)。（10分） 1）、答：組成該零件的形狀特征：圓角長(zhǎng)方形底座兩個(gè)拉伸圓柱體肋板倒圓角及倒角2）、答：畫(huà)圖步驟如下：第一步：建立底座：底座草圖，拉伸建立底座；第二步：在底座上建立凸臺(tái)、孔特征：；第三步：建立第一個(gè)圓柱

4、特征：圓柱草圖，拉伸建立圓柱；第四步：建立第一組肋板特征：，并與第一個(gè)圓柱特征和底座求和；第五步：建立第二組肋板特征：肋板草圖拉伸建立肋板；第六步：建立第二個(gè)圓柱特征：拉伸建立圓柱，并與底座、第二組肋板求和；第七步：建立第二個(gè)圓柱上的孔特征：；第八步：創(chuàng)建各個(gè)倒圓角、倒角特征：；第九步：零件創(chuàng)建完成：；四、采用立式數(shù)控銑床加工下圖所示零件（從清晰性考慮，給出了兩種三維圖，尺寸自定）的曲面內(nèi)腔，使用刀具為12mm球頭銑刀，工件材料為鑄鐵。如果使用UG軟件進(jìn)行數(shù)控編程，簡(jiǎn)要敘述編制該曲面內(nèi)腔數(shù)控加工程序的步驟（分步驟進(jìn)行文字表述，并配適當(dāng)?shù)暮?jiǎn)圖說(shuō)明）。（20分） 答：第一步：用UG中的型腔銑用適合

5、尺寸的刀具對(duì)工件進(jìn)行開(kāi)粗除去工件較多的毛胚第二步：用稍微小點(diǎn)的刀具對(duì)工件進(jìn)行二次開(kāi)粗除去工件首次沒(méi)有加工到位的毛胚第三步：用12的球頭銑刀進(jìn)行對(duì)工件曲面進(jìn)行的半精加工用固定輪口銑第四步：12的球頭銑刀進(jìn)行對(duì)工件曲面進(jìn)行的精加工用固定輪口銑走刀角度為45度第五步：中心鉆對(duì)工件上的孔進(jìn)行定位加工五、下圖所示曲柄活塞機(jī)構(gòu)由活塞(零件1)、活塞銷(xiāo)(零件2)、連桿(零件3)、曲柄軸(零件4)、左曲柄(零件5)、右曲柄(零件6)六個(gè)零件組成。在UG中已完成六個(gè)零件的三維建模，如需繼續(xù)在UG中對(duì)其進(jìn)行裝配建模，得到如下圖所示的三維裝配模型，試給出建立該曲柄活塞機(jī)構(gòu)三維裝配模型的主要步驟（分步驟進(jìn)行文字說(shuō)明，

6、并配適當(dāng)?shù)暮?jiǎn)圖說(shuō)明）。（20分）654321答：六、某線圖的五個(gè)點(diǎn)如下左圖所示，各點(diǎn)坐標(biāo)如右表所示。（20分）l 如采用線性插值原理進(jìn)行線性插值，試?yán)L出實(shí)現(xiàn)插值計(jì)算的計(jì)算機(jī)程序流程圖。l 采用某種計(jì)算機(jī)編程語(yǔ)言（如C、Basic），編寫(xiě)一段程序?qū)崿F(xiàn)該線圖的線性插值計(jì)算。2.編程：xOffset = 1;if (nargin=2) | . (nargin=3 && ischar(varargin3) | . (nargin=4 && (ischar(varargin4) | strcmp(varargin4, 'extrap'); end % Pr

7、ocess Y in INTERP1(Y,.) and INTERP1(X,Y,.)y = varargin1+xOffset;siz_y = size(y);% y may be an ND array, but collapse it down to a 2D yMat. If yMat is% a vector, it is a column vector.if isvector(y) if size(y,1) = 1 % Prefer column vectors for y yMat = y.' n = siz_y(2); else yMat = y; n = siz_y(1

8、); end ds = 1; prodDs = 1;else n = siz_y(1); ds = siz_y(2:end); prodDs = prod(ds); yMat = reshape(y,n prodDs);end% Process X in INTERP1(X,Y,.), or supply default for INTERP1(Y,.)if xOffset x = vararginxOffset; if isvector(x) error('MATLAB:interp1:Xvector','X must be a vector.'); end

9、if length(x) = n if isvector(y) error('MATLAB:interp1:YInvalidNumRows', . 'X and Y must be of the same length.') else error('MATLAB:interp1:YInvalidNumRows', . 'LENGTH(X) and SIZE(Y,1) must be the same.'); end end % Prefer column vectors for x xCol = x(:);else xCol =

10、(1:n)'end % Process XI in INTERP1(Y,XI,.) and INTERP1(X,Y,XI,.)% Avoid syntax PP = INTERP1(X,Y,METHOD,'pp')if ppOutput xi = varargin2+xOffset; siz_xi = size(xi); % xi may be an ND array, but flatten it to a column vector xiCol xiCol = xi(:); % The size of the output YI if isvector(y) % Y

11、 is a vector so size(YI) = size(XI) siz_yi = siz_xi; else if isvector(xi) % Y is not a vector but XI is siz_yi = length(xi) ds; else % Both Y and XI are non-vectors siz_yi = siz_xi ds; end endend if xOffset && isreal(x) error('MATLAB:interp1:ComplexX','X should be a real vector.&

12、#39;)end if ppOutput && isreal(xi) error('MATLAB:interp1:ComplexInterpPts', . 'The interpolation points XI should be real.')end % Error check for NaN values in X and Y% check for NaN'sif xOffset && (any(isnan(xCol) error('MATLAB:interp1:NaNinX','NaN is

13、 not an appropriate value for X.');end % NANS are allowed as a value for F(X), since a function may be undefined% for a given value.if any(isnan(yMat(:) warning('MATLAB:interp1:NaNinY', . 'NaN found in Y, interpolation at undefined values nt',. ' will result in undefined valu

14、es.');end if (n < 2) if ppOutput | isempty(xi) error('MATLAB:interp1:NotEnoughPts', . 'There should be at least two data points.') else yi = zeros(siz_yi,superiorfloat(x,y,xi); varargout1 = yi; return endend % Process METHOD in% PP = INTERP1(X,Y,METHOD,'pp')% YI = INTE

15、RP1(Y,XI,METHOD,.)% YI = INTERP1(X,Y,XI,METHOD,.)% including explicit specification of the default by an empty input.if ppOutput if isempty(varargin3) method = 'linear' else method = varargin3; endelse if nargin >= 3+xOffset && isempty(varargin3+xOffset) method = varargin3+xOffset

16、;else method = 'linear' endend % The v5 option, '*method', asserts that x is equally spaced.eqsp = (method(1) = '*');if eqsp method(1) = ;end % INTERP1(X,Y,XI,METHOD,'extrap') and INTERP1(X,Y,Xi,METHOD,EXTRAPVAL)if ppOutput if nargin >= 4+xOffset extrapval = vararg

17、in4+xOffset; else switch method(1) case 's','p','c' extrapval = 'extrap' otherwise extrapval = NaN; end endend % Start the algorithm% We now have column vector xCol, column vector or 2D matrix yMat and% column vector xiCol.if xOffset if eqsp h = diff(xCol); eqsp = (no

18、rm(diff(h),Inf) <= eps(norm(xCol,Inf); if any(isfinite(xCol) eqsp = 0; % if an INF in x, x is not equally spaced end end if eqsp h = (xCol(n)-xCol(1)/(n-1); endelse h = 1; eqsp = 1;endif any(h < 0) xCol,p = sort(xCol); yMat = yMat(p,:);if eqsp h = -h; else h = diff(xCol); endendif any(h = 0) e

19、rror('MATLAB:interp1:RepeatedValuesX', . 'The values of X should be distinct.');end % PP = INTERP1(X,Y,METHOD,'pp')if nargin=4 && ischar(varargin3) && isequal('pp',varargin4) % obtain pp form of output pp = ppinterp; varargout1 = pp; returnend % Interp

20、olatenumelXi = length(xiCol);p = ;switch method(1) case 's' % 'spline' % spline is oriented opposite to interp1 yiMat = spline(xCol.',yMat.',xiCol.').' case 'c','p' % 'cubic' or 'pchip' % pchip is oriented opposite to interp1 yiMat = pc

21、hip(xCol.',yMat.',xiCol.').' otherwise % 'nearest', 'linear', 'v5cubic' yiMat = zeros(numelXi,prodDs,superiorfloat(xCol,yMat,xiCol); if eqsp && any(diff(xiCol) < 0) xiCol,p = sort(xiCol); else p = 1:numelXi; end % Find indices of subintervals, x(k)

22、<= u < x(k+1), % or u < x(1) or u >= x(m-1). if isempty(xiCol) k = xiCol; elseif eqsp k = min(max(1+floor(xiCol-xCol(1)/h),1),n-1); else ignore,k = histc(xiCol,xCol); k(xiCol<xCol(1) | isfinite(xiCol) = 1; k(xiCol>=xCol(n) = n-1; end switch method(1) case 'n' % 'nearest

23、' i = find(xiCol >= (xCol(k)+xCol(k+1)/2); k(i) = k(i)+1; yiMat(p,:) = yMat(k,:); case 'l' % 'linear' if eqsp s = (xiCol - xCol(k)/h; else s = (xiCol - xCol(k)./h(k); end for j = 1:prodDs yiMat(p,j) = yMat(k,j) + s.*(yMat(k+1,j)-yMat(k,j); end case 'v' % 'v5cubic&#

24、39; extrapval = NaN; if eqsp % Data are equally spaced s = (xiCol - xCol(k)/h; s2 = s.*s; s3 = s.*s2; % Add extra points for first and last interval yMat = 3*yMat(1,:)-3*yMat(2,:)+yMat(3,:); . yMat; . 3*yMat(n,:)-3*yMat(n-1,:)+yMat(n-2,:); for j = 1:prodDs yiMat(p,j) = (yMat(k,j).*(-s3+2*s2-s) + . y

25、Mat(k+1,j).*(3*s3-5*s2+2) + . yMat(k+2,j).*(-3*s3+4*s2+s) + . yMat(k+3,j).*(s3-s2)/2; end else % Data are not equally spaced % spline is oriented opposite to interp1 yiMat = spline(xCol.',yMat.',xiCol.').' end otherwise error('MATLAB:interp1:InvalidMethod','Invalid method

26、.') endend % Override extrapolationif isequal(extrapval,'extrap') if ischar(extrapval) error('MATLAB:interp1:InvalidExtrap', 'Invalid extrap option.') elseif isscalar(extrapval) error('MATLAB:interp1:NonScalarExtrapValue',. 'EXTRAP option must be a scalar.'

27、;) end if isempty(p) p = 1 : numelXi; end outOfBounds = xiCol<xCol(1) | xiCol>xCol(n); yiMat(p(outOfBounds),:) = extrapval;end % Reshape result, possibly to an ND arrayyi = reshape(yiMat,siz_yi);varargout1 = yi; %-% function pp = ppinterp %PPINTERP ppform interpretation. switch method(1) case

28、'n' % nearest breaks = xCol(1); . (xCol(1:end-1)+xCol(2:end)/2; . xCol(end).' coefs = yMat.' pp = mkpp(breaks,coefs,ds); case 'l' % linear breaks = xCol.' page1 = (diff(yMat)./repmat(diff(xCol),1, prodDs).' page2 = (reshape(yMat(1:end-1,:),n-1, prodDs).' coefs = c

29、at(3,page1,page2); pp = mkpp(breaks,coefs,ds); case 'p', 'c' % pchip and cubic pp = pchip(xCol.',reshape(yMat.',ds, n); case 's' % spline pp = spline(xCol.',reshape(yMat.',ds, n); case 'v' % v5cubic b = diff(xCol); if norm(diff(b),Inf) <= eps(norm(xCol,Inf) % data are equally spaced a = repmat(b,1 prodDs).' yReorg = 3*yMat(1,:)-3*yMat(2,:)+yMat(3,:); . yMat; . 3*yMat(n,:)-3*yMat(n-1,:)+yMat(n-2,:); y1 = yReorg(1:end-3,:).' y2 = yRe