• Overview

Generating Centerline Coordinates for Deflected Springs

ASD7.14 includes the ability to export the 3D centerline coordinates to .CSV files. The coordinates are produced based on the geometry of the spring in the free condition. However, it is not difficult to change a few inputs to get centerline coordinates for deflected springs.

For this example we use an extension spring design with machine hooks based on the following inputs – 0.1” wire diameter; 1.0” coil OD; 4.0” free length; 3 tapered coils on each end resulting in a 0.25” diameter reduction. The spring is to be cycled between lengths of 5” and 8”. Inputs are in bold.

Here is the resulting plot of the centerline coordinates in the free condition. The pitch is the same as the wire diameter. We can use the new Export 3D option in the Tools menu to export these coordinates to a .CSV file.

Now suppose we want to create a second .CSV file with the coordinates of the same spring deflected to a length of 8.5”. The first step is to change the Total Coils value to an input. To do this, click in that field and then click the “Convert to Input” icon.

The value becomes bold, verifying that it is now an input.

Next, change the configuration from Close Wound to Pitched.

Blank the input for the Pitch value to allow it to be calculated. Input 0 for Hook Extension to force all the deflection to the pitch. Input 8.5 for the Free Length and blank the cycle point inputs. You should now see that the pitch is calculated and the centerline plot is updated.

Now use the Export 3D tool again and save the file with a new name reflecting the length change.

There are several things to note. The initial tension changed to 0 when the configuration was changed to Pitched. That can be ignored as the goal is simply to get the pitched coordinates. The resulting plot coordinates show the spring deflected to the desired 8.5 inches. However, it assumes that the pitch is constant for all coils and that is not quite accurate for this example or any springs with varying coil diameters. The larger body coils would deflect slightly more than the smaller end coils