Curve by equation (again)
Curve by equation (again)
(OP)
Refering to back to a previous thread regarding creating a curve by equation. After sorting out my problems with basic mathmatics I eventually got something similiar to what I was after, however I am a bit confused as to how pro is treating the values in the equations.
If I use microsoft excel to plot the curve according to a set of parameters I get one result, then i use pro with exactly the same equation and parameters I get a differnt result. It is as if the units are different.
Can any body shine any light on this matter
kind regards
Dav
If I use microsoft excel to plot the curve according to a set of parameters I get one result, then i use pro with exactly the same equation and parameters I get a differnt result. It is as if the units are different.
Can any body shine any light on this matter
kind regards
Dav
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RE: Curve by equation (again)
If you could give us a little more background on how you have this setup thus far in Pro/e. I would assume you are using a graph and trajpar to help with the curve?
Best Regards,
Heckler
Sr. Mechanical Engineer
SW2005 SP 2.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
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Do you trust your intuition or go with the flow?
RE: Curve by equation (again)
for an explanation of the shape
/* ENTER TOOL STEP OVER
SO = 0.5
/* EMPIRICAL VALUE TO CORRECT SHAPE ERROR
SF = 0.0175
/* ENTER PROFILE ALLOWANCE
PA = 0.1
/* ENTER TOOL CUTTER DIAMETER
CD = 10
/* ENTER SLOT WIDTH
SW = 12.7
/* ENTER NUMBER OF REVOLUTIONS
N = 100
A = ( ( SO * SF ) / 3.141592654 ) / 2
B = ( ( SW - ( 2 * PA ) ) - CD ) / 2
x = ( A * ( t * N * 360 )) - ( B * sin ( t * N * 360 ) )
y = ( B * cos ( t * N * 360 ))
z = 0
The curve is going to act as tool path for milling cutter to follow. If you use the same equations in Excel but remove the 'SF' term, you get what I think is the correct result, however when enter it in pro you get the wrong result. This is why I have added the 'SF' term in the equation for 'A'
Cheers
Dav
RE: Curve by equation (again)
I don't know if this will help (or if it's even correct).
/* (b > a) PROLATE CYCLOID
/* (b = a) CYCLOID
/* (b < a) CURTATE CYCLOID
/*
/* Curve originates on csys.
/* Extends +x (mainly for Prolate), +y.
/*
/* --------------------------------------------------------------------
ra = 4 /* radial segment a.
rb = 4 /* radial segment b.
/* Describe the reference circle center total translation; e.g. circumference.
c_ref = 2 * PI * ra
/* Describe the position of ref circle center as a function of t.
x_ref = t * c_ref
/* Describe reference circle, radial vector rotation at that (t) point.
ref_angle = 360 * (x_ref / c_ref)
/* Describe the angle with respect to csys.
/* (Initial vector direction is 6 o'clock ref csys.)
angle_wrt_csys = 270 - ref_angle
/* Define point rb x,y with respect to ref circle center (at t).
rbx_ref = rb * cos(angle_wrt_csys)
rby_ref = rb * sin(angle_wrt_csys)
/* Describe point with respect to csys.
rbx = x_ref + rbx_ref
rby = rb + rby_ref /* reference circle origin is x = 0, y = rb.
/* Assign the values.
x = rbx
y = rby
z = 0