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One thing to remember is that most compression springs are closed, that is there is a flat portion at either end. What I do is to create a curve by equation and calulate the z dimension from a graph. The equation in the curve looks like this:
/* For cylindrical coordinate system, enter parametric equation
/* in terms of t (which will vary from 0 to 1) for r, theta and z
/* For example: for a circle in x-y plane, centered at origin
/* and radius = 4, the parametric equations will be:
/*&nbs p; r = 4
/* theta = t * 360
/*&nbs p; z = 0
/*---------------------------------------------------------- ---------
R=(OD-WIRE)/2
THETA=TURNS*T*360
Z=evalgraph("SPRING",(T*TURNS))
In the graph I start with a little horizontal for the flat sectionat 1/2 the wire diafrom zero to .5 turns, from .5 to 1 turn I go from 1/2 wire diameter to 1 1/2 wire diameter to represent the closed coil, then I havea line to the other end where I have a similar construction. All the values in the graph and in the curve equations are controlled by dimensions in an outline sketch of the coil and the TURNS parameter I added. After the curve is created I create a VSS for the solid.
One thing to remember is that most compression springs are closed, that is there is a flat portion at either end. What I do is to create a curve by equation and calulate the z dimension from a graph. The equation in the curve looks like this:
/* For cylindrical coordinate system, enter parametric equation
/* in terms of t (which will vary from 0 to 1) for r, theta and z
/* For example: for a circle in x-y plane, centered at origin
/* and radius = 4, the parametric equations will be:
/*& ;nbs p; r = 4
/* theta = t * 360
/*& ;nbs p; z = 0
/*---------------------------------------------------------- ---------
R=(OD-WIRE)/2
THETA=TURNS*T*360
Z=evalgraph("SPRING",(T*TURNS))
In the graph I start with a little horizontal for the flat sectionat 1/2 the wire diafrom zero to .5 turns, from .5 to 1 turn I go from 1/2 wire diameter to 1 1/2 wire diameter to represent the closed coil, then I havea line to the other end where I have a similar construction. All the values in the graph and in the curve equations are controlled by dimensions in an outline sketch of the coil and the TURNS parameter I added. After the curve is created I create a VSS for the solid.
The spring itself and curved ends are not blended, in fact there are gaps between them. I have just created trajection curve from the endpoint of the spring (helical surface) and on planes parallel and normal to that end, since I don't need exact geometry, just to order more or less standard spring and to show basic shape of the spring.
Sometime back I had created a compression spring with sqared ends. Using some basic mathematics, I had derived an equation for varaible pich between end of first closed coil and begining of third coil. I could able to generate the entire spring with just one featue that is Helical protrusion. For some strange reasons, I am controlling the free length of the spring through a paramter called "Total_length" given under paramters. Rest of the parameters are defined in "relations" window. Please feel free to coment on the modeling technique.
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