I have to make a thermoforming mold for polycarbonate, in order to get 4 cylinder sections
I want to use plywood, which is bendable for the cylindrical part and standard for the structure.
I would have liked to assemble the panels with mortises/tenons, and luckily this function exists. After a few tries here is what I get:
For the moment I have made 2 pieces because I didn't manage to put everything in a sheet metal room. The cylindrical part is modeled as follows: - Bent-base sheet -Unfold - 2nd Folded base sheet (perpendicular to the first one for making mortise tenons) - Mortise Tenon - Fold - Body delete keep (to remove the 2nd sheet)
The structure is made in 1 piece in sheet metal functions and the mortises between the cylindrical part and the structure are made with the imprint function in an assembly
My questions: - Is it possible to do everything in one room?
- mortises in the middle of a panel?
- is it possible to automatically modify the tenons and mortises to have the release of a cutter
If you make the curved piece out of wood, why not make a simple arched groove on the "cheeks"? Not sure that studs on CP is the best and most solid solution.
From a machining point of view, I don't see how you are going to proceed to make the mortises in an arc without numerical control.
Although there is the solution to use a manual milling machine like a compass in both cases (groove and mortise).
I assume that your mold is a positive mold and not a negative one.
I don't know if you have a lot of experience in thermoforming, but the PC is quite difficult to work with because it forms less well than PVC or ABS and as your mold is made you will have wrinkles (in the jargon we call these corner saddles and forming defects which will complicate your subsequent routing.
Moreover, if you make more than one piece, I don't give much of your mold without any reinforcements in the concave part. The pressure to bear is much greater than people generally imagine. Take 10 N in relation to the total surface and you will see if you also have your sides which are not perfectly square and thin at that.
In your place I would take an exotic wood and I would carve the shape of the half cylinder out of the mass. And I would add an elevation to be sure to have a thermoformed half round, which will not be the case with your mold as I see it.
Out of curiosity what will be the thickness of your PC and the size of your sheets? I assume you're doing vacuum forming! Can you post a diagram or the part you want to get because you say "in order to get 4 cylinder sections" (I have doubts ;-) )
Kind regards
PS: it's just to discuss according to my experience in the field, you can ignore my remarks I wouldn't be offended ;-) ;-) ;-)
Indeed this mold is positive or male, because the dimension to be respected is that of the inner diameter.
Not a big experience in thermoforming, but I've already made sections of dome, and that went well
Here are the scaled-down tests
the mold was actually machined in a CP stock but the shape required it, and much less developed.
I can and have thought of reinforcing the rounded part by putting a torque in the middle, I also leave a slight oversize to have the 1/4 of the cylinder I wanted
The PC to be formed is 10mm thick, 4 parts to be made, I have to leave some play between each parts, it's mounted on a metal structure
From what I see of your mold on the photo it is indeed a negative mold (the negatives are hollow or concave if you want.)
EDIT:: but your new mold with the grooves or mortise tenons is a positive mold.
In addition, you don't have a counter mold or a piece dressed with felt that would serve as one.
So you don't use vacuum forming to form your part: which means that the flat plate deforms by itself under the action of the heat of gravity but maybe you accompany it manually in one way or another.
In addition, you don't have a counter mold or a piece dressed with felt that would serve as one. Note that this would help so that when cooling the room does not tighten, which is common with the PC.
I may not have the compass in my eye anymore but on your first drawing and your photos I have the impression that you don't have 90° between each edge. It doesn't seem like you'd need at least five pieces and not 4 to make a cylinder.
I must have misunderstood the statement ;-) but as I don't retake the entrance to the polyclinic you can explain to me.
