漸開(kāi)線的公式是
+ y, W5 l0 ~) Ux=r(cos(theta)+theta*sin(theta))
% V& D# P# i8 G# P. sy=r(sin(theta)-theta*sin(theta)) & r$ _, S7 X- C$ d* P. A7 Q! x
r - 基圓半徑 ( [+ r" y2 r+ J6 ?/ G
theta - 成形角,弧度值
1 K" C# k4 ^$ B6 M; P$ h8 O在不同theta時(shí)算出x和y即可,。 9 Y# }; Z. H5 N6 g, L
我用Autolisp做了個(gè)程序,,希望對(duì)大家有用。歡迎大家討論,。這里用的極坐標(biāo),。
) l( A! j& Y3 ]% F; Z1 ?) g;************************************************************************************* ;This program is to draw a involute in AutoCAD, anyone can use it freely without permission. ;Take the risk youself, suggest you to open a new drawing and run this program first, then ;copy it to your drawing. ;Chen Xiangsong ; ;Distance Offset: means when you draw a curve rather than a standard involute. ; it starts to draw the curve not from the base circle. ; it is curtate or prolate involute. it is useful as you draw gear root. ; standard involute, enter 0 ; ;Radius of Base Circle: You have to know the meaning, or the program is useless to you ; ;Angle to go: means the length of involute you want. in degrees. it is not pressure ; angle, it is the pressure angle add involute Phi. ; ;Accurancy: the density of points you want on the curve, the smaller the more accurate. ; but will slow down your pc's speed. I normally enter 0.01 ; ;Center of Curve:  LEASE PICK A POINT ON THE SCREEN RANDOMLY, IT IS VERY IMPORTANT. ; DON'T PICK A SPECIAL POINT. That's the disadvantage of my program.
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7 S1 F1 u1 l3 n+ b& C, f(defun c:involute () (command "_undo" "be") (setq os (getvar "osmode")) (setvar "osmode" 0) (setq q 0) (setq f 0) (setq h (getreal "\nDistance Offset:")) (setq r (getreal "\nRadius of Base Circle:")) (setq t (getreal "\nAngle to go:")) (setq n (getreal "\nAccurancy:")) (setq cent (getpoint "\nCenter of Curve:")) + D ~' ~" v7 C) O
(if (= h 0) (command "pline" (list (+ 0 (car cent)) (cadr cent)) (list (+ (/ r 2) (car cent)) (cadr cent)) "" ) (command "pline" (setq trimpoint (list (+ h r (car cent)) ((if (> h 0) - +) (cadr cent) (/ r 1)))) (list (+ h r (car cent)) ((if (> h 0) - +) (cadr cent) (/ r 2))) "" ) ) . p( S: {8 l# C) ~3 c
(while (< f (* t (/ pi 180))) (setq a (atan (* r f) (+ r h))) (setq ri (/ (+ r h) (cos a))) (setq q (- f a)) (setq pt0 (polar cent q ri)) (command "pline" "" pt0 "") (setq f (+ f n)) ) (command "pedit" (entlast) "j" "all" "" "f" "") (command "circle" cent r) (setq bs (entlast)) (command "line" cent (list (+ 1 r h (car cent)) (cadr cent)) "") (setq lt (entlast)) (if (= h 0) (command "trim" bs "" cent "") (command "trim" lt "" trimpoint "") ) (command "erase" lt "")
1 W( b) T$ P8 i. f8 Y& H `(setvar "osmode" os) (command "_undo" "e") (princ) ) |