工作中有时象图1那样的锥形管件的内壁需要加工。但是在图纸上往往仅给出管中段圆弧半径r;圆弧中心到管端面的距离l;管中间内径d;管端内径D。为了求出α角我们采用了以下的步骤: 1.根据已知条件作出几何图(见图2)(1)作管件中心线MN;(2)在M N上取QP=l,过P、Q作M N垂线,截取AQ=BQ,使AQ+BQ=D;CP=DP,使CP+DP=d;(3)取OD=r,以O为圆心,r为半径画圆,并由O向BA之延长线作垂线,交于H; Sometimes the inner wall of the tapered pipe like the one in Figure 1 needs to be machined. However, the drawings are often given only the middle radius of the pipe r; arc center to the pipe end distance l; pipe inner diameter d; In order to find the α angle, we have adopted the following steps: 1. According to the known conditions to make the geometry (see Figure 2) (1) for the pipe center line MN; (2) MN in QP = l, over P, Q Make MN vertical line, intercept AQ = BQ, make AQ + BQ = D; CP = DP, make CP + DP = d; (3) Take OD = r, take O as the center of the circle, To the extension of BA for vertical, to H;