View Single Post
  #10   Spotlight this post!  
Unread 24-06-2002, 00:05
archiver archiver is offline
Forum Archival System
#0047 (ChiefDelphi)
 
Join Date: May 2001
Location: Pontiac, MI
Posts: 21,214
archiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond repute
Welding with chain as the ground path...

Posted by Joe Johnson at 2/9/2001 10:38 PM EST


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.


In Reply to: Re: POST YOU WAR WOUNDS HERE
Posted by Matt Ryan on 2/9/2001 7:59 PM EST:



Late one night last year we were keeping our welder
busy with tons of last minute tabs and brackets to weld
on to our machine.

We had been welding on "the clam" for a hour our so
(not continuously) when without thinking much about it
we repositioned our arm to let Woody (our master
welder) get a better angle on some gusset or other.

Before we knew what was happening, smoke started coming
out of our van door motors and out of our boom chain.

Again, without thinking, I felt them motors. They were
not hot. Then I put my hand across the chain. I was
instantly branded! That chain was HOT.

Here is what happened:

The ground path for the weld was a good one when the
robot was upright because the boom was touching the
chassis (where Woody had clamped his ground lead).
When we tipped the robot arm down, we broke that
electical connection. As it turns out, our pivot was
not electically conductive. So the only path to ground
from the clam on the arm was through the motor shafts
and through the chain.

The smoke from the motor was from the oil in the
bushing that supports the output shaft.

The smoke from the chain was from teh oil in the roller
chain joints.

The smell was from the skin that was vaporized on
contact ;-)

Now I know what not to do when I see something smoking!

Joe J.



__________________
This message was archived from an earlier forum system. Some information may have been left out. Start new discussion in the current forums, and refer back to these threads when necessary.