I needed a spring that I could use as a flexible component. It is a closed spring, so the pitch is different at the ends of the spring. I could have used the helical sweep tool, but I always fight with getting the variable pitch to work correctly and I wanted a bit more control. I decided to use a variable section sweep driven from a datum graph instead.
The datum graph that I used is shown below:
The X-Axis is distance along the spring, and the Y-Axis is number of turns. The spring that I am using is 3 inches in length, has a wire diameter of 0.041 inches and has 27 turns. The spring is closed so the first and last turn each use one wire diameter (0.041 inches) of the length of the spring, while the other 25 turns take up the rest of the spring's length (2.918 inches).
I create the foundation of the spring's geometry by sweeping a line around a trajectory. To spin the swept line around the trajectory I feed (trajpar * spring_length) into the datum graph to calculate what turn I am on, which I multiply by 360 degrees to get the angle of the line (which is sd5). The relation is shown below:
number_of_turns = evalgraph('SPRING_TURN_NUMBER', trajpar*spring_length)
sd5 = number_of_turns * 360
The result initially looks great (swept feature on left, and the final spring geometry on the right):
If I highlight the the swept surface (the image on the left above) I see some really funny stuff going on:
Can anyone tell me what is going on here? The crazy going on along the axis of the spring shouldn't be there. Is this harmless visual junk that Creo is spitting out, or a symptom of an underlying problem with my relations in the Variable Section Sweep.
Any thoughts are much appreciated.
Edit: Re-Attached Broken Images