Cable/Chain Design in SW

[MadMango]

I'm having trouble trying to design systems that utilize chains or cables that have to route around gears, rollers, sprockets or cams. I would like to know how you are accomplishing this task, in the hopes that it will turn on a few lights for me.

I am most interested in what techniques you are using in SW to simulate these types of movememnts during the design phase. Most of my design work revolves around fixed pivots, linear actuators and simple hinges. Now I have to design something similar to a chain or cable being fixed at one end, with the other attached to an eccentric cam to provide more/less movement at certain times.

I usually build a layout sketch first (skeleton?), which represents all major moving components. I drive this layout with dimensions to ensure my geometry works well, then I instert that into an assembly and start creating simplified parts in-context to the layout. Once these parts cover all major compnents, I loose the in-context relations and start to detail the subsystems into their respective components.

Thanks to all. "The attempt and not the deed confounds us."

 

[Mechanicam]

HI ,This is Mr. Hamed Pishvaei
I have read your problem.For this type of cable I use Layout scetch.I mean creating a part in the context of an assembly.I have one sample for you if you want.
Contact me for it by Mechanicam@hotmail.com

best regard

 

[MadMango]

Thank you Mechanicam, but maybe I should explain further.

I am looking for a method that will allow me to push/pull a cable/chain around sprockets/gears in my design that will allow me to see this motion accurately. "The attempt and not the deed confounds us."

 

[Stoker]

If you do this on a regular basis you may want to consider COSMOS Motion. It will simulate the mechanisms and allow you to create movie files and analyze the motion. It is integrated with SolidWorks and is your best bet if you need full-featured motion analysis.

If you only need to simulate the motion occasionally, you might be able to save yourself some money by using the API to drive the animation. You can't use Animator for this because with cable/chain you aren't dealing just with moving components. You also have the cable component which is changing shape as the mechanism moves. You need to adjust the driving dimensions/mates and rebuild the assembly repeatedly to simulate this. I have used equations to update the cable path sketch dimesions such that the total cable length stays constant as the various lengths in the path sketch change. Here is a simple example of how you might drive a mechanism and update the cable path sketch dimensions (H and V). This would be a custom job each time, but for simple mechanisms wouldn't be very difficult.

******************************************************
Option Explicit

Dim swApp As Object
Dim Part As Object
Dim start As Single

Const TotalLength = 1

Sub main()

Set swApp = CreateObject("SldWorks.Application&quot
Set Part = swApp.ActiveDoc

Do While Part.Parameter("V@Sketch1@Cable.Part&quot.SystemValue > 0.1
Part.Parameter("H@Sketch1@Cable.Part&quot.SystemValue = _
Part.Parameter ("H@Sketch1@Cable.Part&quot.SystemValue + 0.01
Part.Parameter("V@Sketch1@Cable.Part&quot.SystemValue = _
TotalLength - Part.Parameter("H@Sketch1@Cable.Part&quot.SystemValue
Part.EditRebuild
Part.GraphicsRedraw

start = Timer
Do While Timer < start + 0.01
DoEvents
Loop

Loop

End Sub

 

[Stoker]

Incrementing the driving dims and then updating the assembly will give jerky motion on the screen, even if you
go down to very small increments. While this is probably acceptable for your own use, if you want others to see the motion then it might be a good idea to write out an image of the assembly at each step and use a video editor to pull them all into an AVI file.

 

[EdDanzer]

You can simulate roller chain as an assembly, this will be time consuming and a resource hog. The cable will be similar to modeling hoses subject to movement. I have ask for the ability to do this since 1996. To date I haven't heard of any software that does this.

 

[MadMango]

Thanks to all that have replied. Stoker, you have confirmed what I was thinking, that I would have to incrementally edit lengths of my cable/chain to simulate their use in an assembly, and that there is presently no way to do simple drag motions.

Happy New Year to all. &quot;The attempt and not the deed confounds us.&quot;