problem with relative rotation

[xLOGANx]

Good afternoon to all! ! !
I write to ask you for help, a hand, to solve a problem. Forgive the image very rough, but I had little time to prepare it. :tongue:
in the figure is represented a lifting group of a plan (in section obviously). the fixed plate, at the bottom, has a circular pocket inside which is inserted this tube called inner column. There is then a welding cord that keeps everything. the plate is then connected to a mobile frame that is represented here.
inside this column, there is an oleodynamic piston that will help to lift the floor I told you. the external column, that is the second tube, flows on the inner column due to the effect of the piston: The bushings, visible in the photo, are used to ensure linear operation. the piston rod acts on the push cylinder (a cylinder obtained from the full for turning), allowing the lifting of the structure above.
In principle, this is the description of the system sto. the problem that I put to you concerns the relative rotation of the outer tube compared to the inner tube, which must not be absolutely there. the only movement to be ensured is the simple translation of the outer tube compared to the internal one.
would you have to recommend me some solutions?? I would have found one, but it seems too turkey (if you want I also place the image of my solution). I'm convinced there's something easier... but I can't see it.
also because, everything must be inexpensive and removable; My solution, on the other hand, makes the replacement of the piston uneasy.
thank you all, girl!!! !

 

[xLOGANx]

:frown: 134 visits....and not one answer:frown:

raga....but it's an exposition problem (you can see what I wrote)....or really there are no solutions??

 

[MFT]

:frown: 134 visits....and not one answer:frown:

raga....but it's an exposition problem (you can see what I wrote)....or really there are no solutions??

you can put a fixed driving rod down and a bushing that runs us axially fixed to the translating pipe.

Mar

 

[pecos]

I would try to hypothesize a square welded outside the inner tube, with sunshades on the sliding bushings......

 

[Fulvio Romano]

or make square columns. . .

 

[xLOGANx]

already.... but the square section tubes did not want them, as well as the elliptical section tubes (which also solved the problem). :frown:
I hope, later, to post the image with the solution I had imagined.
Anyway, thank you for the tips. :finger:

 

[scalva]

put an external stem
or do a milling in the tubes and put a guide pin

Can you give us some size x evaluate better?

 

[xLOGANx]

So, guys, put two pictures about the solution that came to my mind. the groove of the tube, resulting in a "dented" bushing, had been proposed to the client at the time: Unfortunately, the idea was rejected because too "holy" in terms of time spent.

the first image, shows the view in section of the two sliding columns in each other, the piston, the upper plate and then the bushings. appears, however, a square tube inside the outer column. Figure 2, always in section, perhaps is slightly more explanatory. you see the outer column (circular seat) and this inner tube with square section. There is also a window for the positioning of the key that controls the piston. Obviously, the flangeed bushing has a square central hole. the bushing is inserted, as shown in Figure 3.

I keep thinking that it is very artificial as a solution.

thanks raga:wink:

 

[Fulvio Romano]

If the components that rotate the system are not too large, you might think of an external structure.
imagine a pin outside the outer column, at the bottom end. This slides into a guide fixed at the bottom of the inner column and that, as a swing, embraces the whole outside column.
then for symmetry put a second at 180°.

Unclear, right?

 

[vale61]

provided that they do not know: rotation efforts, tolerance allowed on rotation, diameters (therefore useful thicknesses) of guide columns.

I would also do as already proposed, one/(two 180° radial plugs) to the internal (or external) driving column that flow into a passing quarry performed in the external (or internal) driving column, of course that if the allowed tolerances on rotation are "street" it is necessary to move to more precise/ expensive solutions.

Bye-bye.

 

[xLOGANx]

the idea of the milling of the pipes to create grooves, within which to stay one or two pins was presented at its time. is simple and clean: Despite this, it was not accepted because... I quote "you see the grooves from the outside and, instead, from outside you must not see anything".

I keep thinking about it!!!! of course... thank you!!! :biggrin:

 

[stefanobruno]

from outside must not see anything."

You do the groove inside and you put the pins out.
I honestly didn't understand your pattern well, did you go further?

 

[xLOGANx]

boys...you place 2 pictures: I hope I understand. the problem of this solution lies in the size: the outer column has an east diameter of 50 mm and an int of 47 mm. while, the inner tube has an external diameter of 45 mm (of course, these are the tubes they had available).
for this reason, the groove could have a depth of 0.75 - 0.8 mm which, frankly, seems a little bit to me.
Secondly, we should also channel the bushing that lies down...otherwise it does not fit.... and this means we can not buy bushings that are commercial. :frown:

I hope I have not sung in understanding:

Hi.

 

[cacciatorino]

boys...you place 2 pictures: I hope I understand. the problem of this solution lies in the size: the outer column has an east diameter of 50 mm and an int of 47 mm. while, the inner tube has an external diameter of 45 mm (of course, these are the tubes they had available).
for this reason, the groove could have a depth of 0.75 - 0.8 mm which, frankly, seems a little bit to me.
Secondly, we should also channel the bushing that lies down...otherwise it does not fit.... and this means we can not buy bushings that are commercial. :frown:

I hope I have not sung in understanding:

Hi.

consider one thing:

even if your guide was very precise, a small corner game, given the proximity to the center on which the anti-rotation mechanism is located, would certainly cause a discreet linear osillation at the extreme points of your suspended structure.

try to see if you can use a preloaded ball mechanism, for example:
http://it.misumi-ec.com/eu/ecsearchview.html?kw=rgpfsor if you have little precision necessities a component like a bosch slider on aluminum profile:
http://www.boschrexroth.com/is-bin/...catalog=de_mtn&bridgepageid=node6920767574620

 

[xLOGANx]

excuse the delay in the answer (bad influence ). However, I try to see these two mechanisms reported by hunter. I didn't think so. for the problem related to the angle game... yes, actually it is a present problem. Fortunately, the guide does not need precision pushed as, as mentioned at the beginning, the system must lift a plan on which other elements rest. I'll let you know.
as always thanks:finger: