Gang,
I have sent some pictures to the dropbox to reference a problem I'm
having where I work. We use a grinder to "flatten" the cutting edges
of 4-winged knives used in a meat grinder (to make hamburger). The
machine being used has a 7" circular magnetic chuck, 90Vdc with
concentric rings. The knife is placed in the center of the round
chuck with the cutting edges up, and the stone (8" x 3") is spinning
and lowered down to flatten the cutting edges (some of which are
stellite) and then the knife is taken to another grinder to "relieve"
the flattened portion to product a cutting edge which will press flat
against a circular disk with holes in it for the hamburger to press
through.
The problem we are having is that there is not enough metal on the
backside of the knife for the mag chuck to get a good grip onto - and
the knife will sometimes slide away from the center of the mag chuck.
This causes problems with the grind - and also sometimes the knife
will just fling off the chuck and hit the side wall of the grinder.
As the center of the mag chuck is "probably" the weakest point of the
mag chuck (which is fed the 90vdc through slip rings under the coolant
box) I was wondering if a round magnetic chuck with parallel
laminations would be stronger magnetically than what we currently are
using. I have cleaned the slip rings, checked the voltages and the
brushes and everything is about as good as I can get it. Many times
we will grind the back side of the knife to get a better magnetic grip
on the knife. A gig such as a plate with a square post sticking up
would probably also work, but there are about 6 different sizes and we
would have to make/have made 6 different "post plates" - we are trying
to avoid having to do that.... Any suggestions?
The links to the pictures in the dropbox a
http://www.metalworking.com/dropbox/magchuck.txt
http://www.metalworking.com/dropbox/magchuck1.jpg
http://www.metalworking.com/dropbox/magchuck2.jpg
http://www.metalworking.com/dropbox/magchuck3.jpg
Thanks for any suggestions.
Ken.