Perimeter

[ledo]

I draw involute spur gear and in tutorial icame across term "perimeter".


I google it and found definition.


http://en.wikipedia.org/wiki/Perimeter


But i dont know still what is the purpose of perimeter in proe and how to made one.


I attach the picture from tutorial and draw a red elipse around the perimeter. And why does some values have "var" after the number?

 

[vlad1979]

It's for dimensioning the length of a curve.


In WF2 / in sketch mode select the curve then go to edit / convert to perimeter and then click on a dimension you want to convert it to perimeter. And that dimension will become "var"=variable it will change automatically when you enter a new value for the perimeter.
Edited by: vlad1979

 

[ledo]

Thanx i found it.


But i have one more problem regarding the picture. How do i make a angular dimension on the picture to apply perimeter to it.





I have only the dimension L4.375000 in the picture and dont know how to add the angular dimension 14.733200 so i could apply perimeter to it.

 

[ledo]

Nobody knows?

 

[jeff4136]

That's also in Help under
... / Creating Major Dimension Types / To Create an Angle Dimension for an Arc:
Pick each end of the arc, then pick the curve itself and MMB to place the dimension.

 

[ledo]

Thanx now i found it.

 

[AHA-D]

Perimeter is an excellent tool to simulate bending. The perimeter conversion isn't limited to one part of geometry, you can select a string of objects also. As long as it can be mathematically solved of course.


But in the case of the flat bending it works as follows. You know that a flat spring has a neutral fibre. This is the part that keeps it length while deforming. Start with an arc with a large radius to represent the neutral fibre. When you connect it tangent to a bit of vertical or horizontal line you know for sure that you start out flat. Now create the wall thickness around this neutral fibre but make sure that geometry can follow. So beware of "hard" horizontal or vertical constraints in what you attach. Better to use parallel, orthogonal and so on.


To bend our part we will give a dimension that steers the deflection (top of the arc) in relation to the flat part. You can also give a radius value. Now convert the neutral fibre to perimeter. ProE will ask what variable it can change to keep the perimeter. Give it the radius value. You can now set the deflection minimal, enter the length of the spring as it should be and ProE does the rest. Make it deflect more and you'll see that the radius gets amended to keep the total arc+straight length the same.


There's only one limitation : you can't make the spring flat because that would mean a radius beyond the internal numerical limit.


Alex

 

[ledo]

Thanx for detailed answer.

 

[dasiddiqui]

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