current feedthrough to rotate

I need to fit a high current feedthrough on the vacuum chamber which must be also rotate 90 without disturbing vacuum integrity (10-3 mbar).
What could be best solution ?
Is there any company offering such solution ?
Regards
Pierre
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On Thu, 8 Jan 2004 17:11:01 +0100, in sci.engr.mech "mkson"

You might give a ferrofluidic seal a look. http://www.ferrofluidics.com
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Thanks,
I have allready check their web sites
Pierre
wrote:

be
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There is a classical engineering solution to this need, which is guaranteed to be leak proof.
Place a primary winding on the ouside of the container, tightly coupled to a secondary winding inside the container. The coils axis points though the container wall. Either coil can rotate on this axis with no effect on coupling.
You will say, I expect that the high current is in fact DC. You *could* invert it however.
Brian Whatcott Altus OK

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Brian,
Thanks for reply
But i need only to be able rotate feedthrough which is watercooled.
System such you mention will induce the current also on chamber wall
No winding outside, there is only ac current Thanks
Pierre
wrote:

be
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Dear mkson:

Do you *have* to transfer current through the same feedthrough you transfer angular rotation? Couldn't you commutate it inside the chamber? Forgive me if this is a naive question...
David A. Smith
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Dear David,
Inside the chamber , i need to rotate the induction coil for pouring the molten metal.
same induction coil requires high current 200 amp. @ 250 volt thus must be cooled to avoid overheating damages.
So I have to transfer the current, water and rotary motion on the same axis and keep the vacuum integrity.
Such systems exists, for vacuum induction melting furnaces but cost a lot of money
May be I need to use high conductivity water cooled FLEXIBLE copper tubing than keep the feedthtough fixed ??
Pierre
le message de

transfer
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Dear mkson:

be
axis
of
tubing
Copper has no fatigue strength, so you'd have to replace it every few cycles.
Do you have a sketch you could post a link to, that shows what you are trying to do? Maybe it would trigger something in the "amassed minds" here.
David A. Smith
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David,
Let me know your email address than i will send you the picture
Pierre
le message de

lot
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Dar mkson:
with the appropriate substitutions from either of headers below
"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:ne
(don't want to make it too easy for spammer bots to decipher.)
When I get it, I will post it on webspace for a couple of weeks, so the crew here can take a gander.
David A. Smith
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A vacuum container wall does not have to be conductive!
You didn't like that one? There is another classical engineering response.
Visualize a fixed conductor entry which is capable of looping to the far side of the rotating piece, in line with its axis of rotation.
As the piece rotates, the conductor loops around in the opposite direction to that in which the rotor moves.
Brian W

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Dear Brian,
Vacuum container is 300 series steel thus conductor.
I could not visualize, what you means, is it possible that you send me a sketch or link.?
"fixed conductor entry capable of looping" : You means flexible conductors attached able to have a torsion. ?
Thanks
Pierre
wrote:

must
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A picture of the apparatus is at: URL:
http://members.aol.com/dlzc/feedthrough.jpeg
... in case someone has bright ideas on how to accomplish this task. (I'll host the image for a bit...)
David A. Smith
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It took a while to visualize it, but the optimal solution is quite straight-forward.
Arrange a fixed entry into the chamber for the water-cooling and electrical supply. This could be for example, a copper co-axial tube, with water in the interelectrode gap. This can be absolutely vacuum tight.
INSIDE the chamber, arrange flexible leads to depart the tube end radially. At least two for power, at least two for coolant.
Fix a stub to the rotating crucible, axially aligned with the entrance stub. Arrange the leads from the entry stub tube to loop back and enter this internal roating stub tube axially.
When the crucible rotates, the loops all move slightly, to accommmodate the rotation. No sweat!
Brian W

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Dear Brian Whatcott:

I was wondering how difficult it would be to simply rotate the vacuum chamber, and avoid all the mess...
David A. Smith
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