Not knowing the uses of the forum, I hope not to commit a raincoat for my first post.
I'm on Solidworks 2016 and I'm slowly getting into Onshape.
I'm looking to draw a hollow bell cam on a cylindrical part. First of all, here's the piece: it's the circular debossed strip
the ends of the hollow
The small blue cylinders are guided on the surface of this cam to have an axial, reciprocating movement.
I have 3 pbs: 1 - Design of the guide curve: Although I have been drawing for years, I have only ever done very simple parts and my knowledge of functions is limited or even close to zero for the use of surfaces. In summary: there is a high point, a low point whose surfaces must be parallel and slopes between to connect them. I tried a circle or ellipse on an inclined plane but when I sweep, my shape does anything and follows incomprehensible trajectories. I ended up managing to draw the thing from 2 portions of a mirrored propeller with a sweep but at the low point, the surfaces are not tangent. Putting a ray is not enough for what I want to do. (if it's not clear, I'll put my piece in a picture but I don't have it on hand).
2 - From my curve, I tried to remove material by scanning, but it doesn't work. I had to create a positive sweep and add volume around it to create the room. I don't understand the pb because I modeled the same functions (scan removal) on Onshape and it works very well.
3 - Once the hollow is created, I don't know how to stress the little blue cylinders because the surface is in several parts. So I can constrain by tangency but only in a given area. I would like to be able to do a simulation of rotational motion.
After some research, I found this topic on another forum that looks very similar to what I want to do, but I don't have the software on hand and couldn't test it (and I didn't understand everything). Maybe you can tell me if it's the same principle. http://www.forum-cao-3d.fr/solidworks-design-surfaces/conception-d-une-came-cloche-t12126.html
Except for the fittings, your trajectory is either a portion of a helical (corresponding to the slope), or a portion of a circle (which apparently you have already found). From these elements, you can define a trajectory (composite curve function) With this trajectory, you can do a "volume scan material removal", using the shape of your blue cylinder.
For the constraint, Sylvain gave you the right answer, and you should be able to reuse the curve that you used for the material removal.
Thank you bcp for the answers. I don't have the software at hand and I haven't understood everything but I'll test it all on Monday at the office. I tell you again.
Personally, I think it's much simpler and cleaner to create a build surface according to the desired inclination or depth and to extrude to this surface. In any case, it will be easier to modify the races and more sure to have something correct.
I'm not saying it's not correct, but I find this method too complicated for something so simple, an inclined plane along a correctly placed axis, an extrusion and presto, it's quick, associative and easy to modify. After that, whoever wants to modify the inclination of either the extrusion or the boundary surface, is much easier to define and study a course or a depth with this method, especially if flat parts are needed at the bottom of the track.
But your method is correct, on the other hand in case of a quick modification I think that someone other than you will take more time to understand your reasoning, and make sure not to mess up.
In short, to each his own methods, I lean more like franck.ceroux
And normally, the concentricity between the surfaces should be the same along the same axis, so the track can be extruded axially to the part (material removal). Then the width of the track depends on the width of the rollers, which are cilyndric, so it should be the same everywhere with a set of works. All this would be more easily controlled with a single sketch
Ok, I get it, in fact we're not talking about the same thing. You mean that the back of the groove includes a twist that allows you to have a perpendicular support between the axis of the roller and the track during the two extreme positions? I was talking about the extrusion direction of the track, I thought there was a leave at the back of the gorge, dsl. In this case you should either do as you did, or do a sweep by specifying a twist.
Considering the head of your part, the cam path is probably made in milling: controlling the descent of a milling cutter (almost identical to your blue parts) while the plate supporting the workpiece rotates.
If so, SW now has a great feature called volume scanning:
Well I see that there is a debate, it means that this piece is not so simple.
Initially, I had used a sweep removal with a curve but I never managed to find the opsions that allowed me to keep the removed profile straight. It twisted and gave anything.
Thank you all for your answers. I'm far from having understood everything when reading the posts but I did a few extra hours and watched the gt22 part. I didn't know the functions used at all and I admit that I rowed a little. I would like to point out that there are several things that are not useful (planes, surfaces, curves) but it allowed me to really understand the principle and suddenly I arrive at a result that looks rather good to me.
I removed the elements that were not necessary, I used a material removal rather than an extrusion and here is what it looks like:
I'm going to print this out and check that everything is okay.
I will also test the other proposals during the week.
