Wave Spring

Here is one answer to the Smalley wave spring questions I've seen lately.

We went to the pro-stuff web site and downloaded a Smalley washer.

We needed springs for our application.

We modified the equation as shown below and all is well. If you find problems with it, please notify me so I can make the appropriate changes to ours.

Here is the equation for the datum curve of the washer we downloaded:

Wave Washer as downloaded from "pro-stuff" website:

/* 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:

/* r = 4

/* theta = t * 360

/* z = 0

/*-------------------------------------------------------------------

"Change these values for your washer"

catalog_dia = .705

desired_ht = .085

num_waves = 3.5

"datum curve calcs below"

r =catalog_dia/2+D17

thk = D15

amp = desired_ht-thk

theta = t*355

z = amp/2*cos(num_waves*theta)

We modified this as follows:

Smalley Spirawave Washer Equation

************************************

/* 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:

/* r = 4

/* theta = t * 360

/* z = 0

/*----------------------------------------------

"Change these values for your washer"

catalog_dia = 1

desired_ht = .1

num_waves = 3.5

"Datum Curve parameters below"

r =catalog_dia/2+D17

thk = D15

amp = desired_ht-thk

theta = t*1440

z = amp/2*sin(num_waves*theta+270)+(desired_ht/360*theta)

Smalley Nested Washer Equation

***********************************

/* 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:

/* r = 4

/* theta = t * 360

/* z = 0

/*----------------------------------------------

"Change these values for your washer"

catalog_dia = .705

desired_ht = .085

num_waves = 4

"Datum Curve parameters below"

r =catalog_dia/2+D17

thk = D15

amp = desired_ht-thk

theta = t*720

z = amp/2*sin(num_waves*theta+270)+((thk/360)*theta)

Parameters requiring your input: catalog_dia, desired_ht, thk, theta

The parameters shown are examples.

We only modified "num_waves" and "z". When "num_waves" is 3.5,

you get a Spirawave. When it is 4, you get a nested spring.

This will give you a datum curve that you can sweep a protrusion along.

D15 is the thickness of the sweep and D17 is the width of the sweep.

I made the red text for differences between the two new equations.

The 270 in the z equation was to get the spring started in the right place so a shim could be added to the top and bottom as seen in the Smalley catalogs.