For a study, I have to implant a screw with left and right pitch threads on the ends.
This screw must be attached to the fixed part (keeping the rotation) and must move two moving parts that are on each side of the fixed frame.
Each part will have to be written in a coordinated way but that's not my concern.
Having never made a system of this kind, I wonder how to implant this screw.
I'm thinking of making a shoulder in the center of the screw, coming to plate two bearings and closing on each side of my bore (in the fixed part of course) with flanges.
After that, all you have to do is screw the 2 elements on the sides at the same time and that's it. (to avoid bending, a second shaft will be implanted)
What do you think of this solution? Does all this seem correct to you or is there another way to implant a screw of this type?
Oh I understood, the question was about the mechanical solution!
Indeed, it is a good solution. However, in our company, we use 2 different screws for a question of cost: machining 2 opposing threads on a single screw will cost significantly more!
A central bearing with a bearing and mounted rings set or a nut with pins allows rotation.
In fact, both parts are used to compress material while hot.
There will be a kind of "funnel" made by 2 chamfers at the entrance (one chamfer on each moving part), hence the bending generated by the forces applied to the chamfers.
After that, I have a whole damping system to do...
But for the layout I will start with my idea by placing my whole set in a bore, which will play the role of protection.
For mounting the screw, it seems to be a good solution.
On the other hand, to simplify the assembly of the moving parts on the sides, it seems safer to me to put flange nuts on them (e.g. http://www.michaud-chailly.fr/ecrou-flasque-perce-vis-trapezoidale-b4-01-03-10/ ). That way, you approach an element, you adjust the position and you fix the nut and then you start again on the other side to be symmetrical. And what's more, it's easier to replace if it wears out.
On the other hand, pay attention to the subject of the shaft which must limit the bending. If I understand the system correctly, there will be forces in the axis of this tree that will not be stopped. So there is still a risk of getting stuck. Or is that what you call damping?
It may not be necessary, but pay attention to the symmetry of the positioning of the two nuts in relation to the bearing: the beginnings of the taps and threads are never oriented angularly.
