How to model a rope winch in NX? 3

[helperug]

I'm not the expert in Nx what to model a rope winch, and how to animate the wining process?
I thought about a helix, how to do the second layer?



sorry new in NX
regards
Erwin

 

[jerry1423]

You may wan to look into use Law Curve

 

[hudson888]

Winding, If you have only one coil maybe it shouldn't be that hard, the geometry is pretty much that of a helix. It's swapping to the second coil (i.e. in an inner or outer layer) that's liable to be tedious.

Best Regards

Hudson

www.jamb.com.au

Nil Desperandum illegitimi non carborundum

 

[Toost]

Do you want to "animate" the winding or model "several layers of wire"?
If you want to model several layers, a relatively fair workaround should be to create multiple helix-es concentric , every other in different turn directions ( Right / Left) and finally connect the "layers" with bridge curves. see attached image.

Regards,
Tomas

 

[ChaseWichert]

You can easily animate the winding of one layer, attached is the video and the file that made the video. It just takes a few expressions linked to the FrameNumber. I'll see if I can play with multiple layers. It maybe easier to do several animations and hook them together.
This is in 8.5

NX 8.5.1.3

 

[ChaseWichert]

Alright I think I figured it out. I'll post the file and animation shortly. If you don't have nx 8.5 I can put together a little thing for you to explain how to do it.

NX 8.5.1.3

 

[ChaseWichert]

The Files are attached. Basically what I did was create the helical curve which consists of bottom layer helix, top layer helix, and a bridge curve to connect them two. I then join all three of those curves together. I put a point on the joined curve that at location of a percentage that is controlled by the FrameNumber expression. I then trimmed the joined curve with the point. As you increase in FrameNumbers the trimmed curve will keep getting shorter and shorter until it reaches the end. I then put in a plane that was based on that trimming point and the Datum Axis which is used in the assembly file as a constraint which keeps the tail or the end of the cable in one position making the drum rotate around. I was going to calculate this and use an associative move object but this was easier, and probably faster. So I took the winch model and assembled it into a new model. I then constrained the Centerline of the cylinder to the datum axis in the assembly file (allows for rotation), and then the face of the cylinder to the parallel plane (keeps the cylinder from moving axially. I then did a touch constraint of the plane that was created in the component file to the last plane in the assembly file. So whenever the point moves a certain percentage, the plane will follow the point and the constraints will always snap it back to the same location it was at at the previous frame, giving the illusion that the cylinder is rotating along the axis instead of the tail rotating about the cylinder. The animation attached looks funny when it gets to the second layer, but that just happened to be because of the settings that I chose. I hope this helps.

NX 8.5.1.3

 

[Toost]

Nice work Chase !

 

[moog2]

I think you'll find a winch doesn't use a helix to wind on the rope or wire.
If you look at the cable on a winch you'll notice that the wire joggles across suddenly at a certain point.
If you wound it on along a helix in one direction, when you go the other way (on the next layer), it would never sit correctly on the layer underneath,
( I can't view your files as I've got NX8 not 8.5)......the groove needs to guide the wire in both directions equally.
(bear in mind after the first layer, the wire can only be influenced by the previous layer, not the groove underneath)
what it needs are RADIAL groove's spaced diameter distance apart, which only extend 180 degrees around the drum, then on the opposite side of the drum, they are offset by half a pitch.
then when the wire goes on, it follows the groove as far as it can before jumping over to the other groove, and so on....
then when you start the 2nd layer, it sits between the wires on the previous layer and only crosses over, across the step over sections, then it'll take on the joggle I spoke of.
If you look at a winch with many layers, you'll see it's no longer a cylindrical coil, but it's "crowned" at the joggled areas, because each layer adds less than a cable diameter, except over the joggle.
If you talk to someone who operates a winch for down hole logging or sampling etc, they'll tell you that the 1st layer on the winch is critical because any fault will get
worse and worse the bigger the reel gets.
These winches have a feeder arm arrangement which is geared to the drum to help the wire go where its supposed to.

 

[Toost]

Moog2, i knew a few bits of this , i have winched a number of boats onto trailers but apart from that my knowledge is almost zero. The impression i have from the boating winches is that it seems "Chaos-controlled", the first layer seems rather logical ( and helical), but then the second, no prediction at all, the wire jumps as a mad spider and suddenly there is three-four-five layers in the center and 1-2 on the sides.
And if there is increasing tension on the wire it will cut trough the existing layers.
- I ,lets say, "ignored" this when proposing the helix methods....
The reality seemed a bit too complex.

Regards,
Tomas

 

[ChaseWichert]

Thanks toost, I ignored this as well. I do have the first layer helix right hand and the second layer (outer) left hand. I have a feeling in his animation it doesn't need to be exactly like real world. However, I believe we have answered the spirit of the question. The method that I proposed would work if he wanted to spend the time to model the guide curve however he wanted.

NX 8.5.2.3

 

[moog2]

It's been 15 years since I worked with wjnches ..... now I remember, the joggle only happens once per rev, so the groove's should be radial, right round, with a machined away gap, at the cross over point. see model....
Toost, I think boat winches would'nt have the feeder arm, so the wire can take its own path, so as you say, a caotic wind is acceptable, and as the weight is fairly low it's no problem.
With down hole logging etc, there are miles of wire, which weigh an awful lot, and if it's not perfect, it'll snap

 

[helperug]

thank you guys for the nice examples you offered.
and discussion is interesting, too.
I'm out out of office this week may, will look at the example when I'm back.
thanks

sorry new in NX
regards
Erwin