[Ocp-europe] RuggedPOD v2 sealing feedbacks and improvements

Benson Muite bensonrt at ruggedpod.qyshare.com
Sun Jul 5 21:43:45 UTC 2015


Hi,

One thing to do might be to increase the contact area and use a thicker
o-ring.

Another option would be to cast the top cover so that it is slightly
curved outwards, with a fixed, less deformable contact surface. A
similar type of joint to what is used in engine combustion chambers may
work:

https://en.wikipedia.org/wiki/Crankcase

Regards,
Benson

On 7/5/15 11:32 PM, Jean-Marie Verdun wrote:
>
> Hi Folks,
>
> I spent some time drawing the concept of the top sealing that we used
> for RuggedPOD v2.
>
> The sealing concept is quite easy to understand. We roughly used a 3D
> torus joint which is standing at the top of the edge of the tank. This
> joint is placed under pressure from the top cover which is bolted to
> the tank using threaded rod which have been pre-assembled into the tank.
>
> This principle is currently not working efficiently and we must find
> the root cause of the issue. The first thing we observed is that most
> of the theaded rod are getting bent or unlocked from the tank. They
> are currently based on stainless steel a strong material with a 3 mm
> diameter.
>
> We used also specific glue to lock them down into the hole which was
> threaded.
> The top surface of the tank edge has been post processed to be
> flatened as much as we could.
>
> Roughly the assembly process is the following one:-
>
> - Solder the tank side to each other
> - Solder the bottom
> - Post process the edge of the top surface of the tanke to flaten it
> - use CNC to create 3D torus joint placement area
> - Put the thread rod in place
> - Run the whole assembly
>
> Looking at some math, when we put the tank under vacuum, I believe
> that the pressure on the top cover is slightly moving to 1kg/square cm
> as the pressure inside the tank is going to 0.007 bar, which means
> about 1.4 tons for the whole cover. This pressure is transferred in
> some way to the tank edges, and stainless steel elasticity is
> exercising a strong force on the threaded rod which are breaking there
> glue link and create some small leakage.
>
> I might be totally wrong, and this is where I need your help !
>
> We urgently need to have a look to this issue, as I would like to
> upgrade asap this design flow. The following options might be explored
> and will be discussed with some of our manufacturing partners this
> week like:
>
> - Embedding the threaded rod during the panel manufacturing process
> rather than gluing them
> - Use higher diameter and longer threaded rod
> - Put one at each corner (currently there is none, and most of the
> leakage are observed in that place)
> - Put them in a Z shape around the 3D torus joint instead of a
> standard aligned position
> - Increase the number of Threaded rod
> - Use bolt with wide pressure area (we are using standard 3mm bolt,
> perhaps using 3mm hole bolt but 6mm contact diameter surface might be
> better)
> - We could also increase the thickness of the top cover, but what will
> be the right one ?
>
> I like to avoid increasing the thickness of the tank panel (which will
> increase the contact surface with the top cover), as it will lower
> heat exchange capacity.
>
> Feel free to jump into the discussion ! JJ will try to run some static
> mechanical simulation tomorrow with solidworks as to understand how
> much pressure each threaded rod have to address. But we are not expert
> in mechanical simulation and if you have some options to help us feel
> free !
>
> Jm
>
>
> -- 
>
> Â  Jean-Marie Verdun
> Â  *Splitted-Desktop Systems*
> Â  President
> Â  Batiment Aristote
> Â  Parc des Algorithmes
> Â  Route de l'orme des merisiers
> Â  91190 Saint Aubin FRANCE
>
> Â  jean-marie.verdun at splitted-desktop.com
>
> Â 
> 	Splitted-Desktop Systems is a proud member of the Open Compute Foundation
> and a Gold member till July '15. We can provide you consulting and
> engineering
> services related to any OCP hardware. We also drive RuggedPOD and Daap
> Open
> Hardware projects
>
>
>
>
>

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