I am attempting to model a weld chain in order to then assemble it in an assembly.
As you know, a chain has a fixed lenght and fixed number & size of its links: I would ambitiously like that when I assemble it, I can position it by making its ends (first and last link points) coincident to two points on the guesting assembly, and then the chain, conveniently designed for the purpose, adjusts its shape in assuming a parabolic (or parabolic-wise) structure as subject to the gravity.
anyone has ever done it and/or has some suggestions on how to?
(I know that for sure it is necessary to use flexibility.)
l have searched my notes about chains and found following.
- Roller chain --- is attached
- Welded chain --- is attached
Chain model with Pro/ENGINEER - YouTube ---- in my opinion it´s the best solution
Sprocket mechanism with Pro/E WildFire 4.0 - YouTube --- l like this video .
Hope all attached files are freeware.
The only way I can think to do this is
(1) Get a good understanding of the mathematical definition of a hanging chain (a catenary). It's not a parabola; here's a possible source of info: Catenary -- from Wolfram MathWorld .
(2) Use the mathematical equations to define a curve that will "drape" between your two connection points.
(3) Define points along the catenary curve you've defined to position the chain links.
(4) Assemble the links onto the points.
As Frank stated, this is a very "tall order". You are going to have to arrange things so you end up with an integral number of links. Assembling the links will probably not be an easy task either, since they have to alternate as you go along. It'd be a fun project, if it was my job to do it.
I've been thinking about this as a fun little aside. You didn't mention orientation of the sprockets, horizontal I take it? How accurate do you NEED (not want) it to be? I might do one for fun, and see if I can't mechanize it with sprockets. For the trajectory, I'd simply use a conic top and bottom to connect the arcs on the left and right, and use a perimeter dimension equal to pitch X number of links to control it. Adjust the rho values to get the sag you expect. Would sag be PARAbolic, or HYPERbolic? An ellipse maybe? Whatever it would truly be from a math standpoint, the rho value could do it.
Oh, are you thinking it's a drive chain? I was thinking it was a welded chain, like on an anchor, or a safety chain. Drive chain would be fun and you might be able to assume minimal or no sag due to the chain being under tension. Although, that is not reality.
It's not parabolic, but defined by a catenary curve. I put a link above for the equations.
thanks a lot for your suggestions and your files, I have downloaded them and they will be extremely useful.
My problem however, (I have not pointed it out clearly maybe) is not much how to do the chain (in my case it is a weld chain this time, but I will certainly have to build a roller chain too in the future), because I already have an idea how to do it (that is quite much what Kenneth wrote in the next post and how reported on your pdf instruction and part).
My problem is that I would like the first and the end links of the chain to be assembled to two whichever points on the guesting assembly and make the chain adapt to those two points, whichever relative position these two points have from each other. I know that this may be done by flexibility, but how exactly shoud I have to do it I don't know, because with flexibility you can adapt a dimension of your flexible component to a length/distance/angle in the guesting assembly, but not directly adapt two points to two points on the guesting assembly. (I hope to have been sufficiently clear).
At this point I am wondering whether may I use the cables application too to do this.
thanks for your suggestions and your link, yes indeed I was wrong it is not a parabola but a catenary.
As I wrote to Milan indeed I already have an idea (and I realized it also) of how to perform the steps 1-4 you mentioned, the main issue is in fact the assembly of the points.
Probably with a fixed point and an axis leading to the other point, with the distance and the angle of the axis as parameters of flexibility.
Yes it's intriguing, even if very much time consuming as I imagine!
Indeed it is a weld chain that I am trying to make, and the main problem is the assembly of the two first and end points, to the guesting assembly. Concerning the equation, it would be a catenary as Kenneth said.
by the way, I cannot open gph files as I have Creo Parametric 2.0, do you know how to convert them into .prt or .asm or could you kindly provide them (as a .stp too at most, just to see them) ?.