flanging 26

The next item of interest on the work order is this:

work order center hole

This lets you know if the head has a center hole or not.  If there is a center hole, it lets you know what size the hole can be.  The default size is two and three-eighths inch max.  Most orders with center holes have this.  This doesn’t mean the center hole has to be this big, only that it can’t be any bigger than this.  Only the thickest heads have a two and a quarter inch center hole.  The most common size for the center hole is an inch and nine sixteenths.  Some customers require a center hole of a certain dimension.  Some customers cut out nearly all of the radius; all they want is the a ring of the icr and straight flange.  These heads are re-drilled, or cut, after they are flanged.

When heads with center holes are loaded into the machine, the center holes fit snugly around the pin in the lower center post bearing.  The upper center post bearing locks down around the pin, to hold the head in place while it is spinning.

But on this order there is no center hole in the head.  It is the dreaded no-hole.  No-hole heads can be a pain in the ass.  First, you have to line them up manually.  Since there is no center hole, you load it onto the lower center post bearing pack, eyeballing where you think the center is.   Then using the forming roll you nudge it into place as it spins, until it spins true.  Once you have the head centered, you clamp down on it with the upper center post bearing pack to lock it in place.

Lock is hardly the word.  It is easy for the head to slip off center.  While you are flanging the head you are moving it and putting a lot of pressure on it.  Also, if the metal is very thick, about a half-inch, the smaller flanging machines don’t have enough pressure to hold it in place.  These heads are constantly slipping off-center.  When that happens you have to stop what you are doing and re-center the head.  Also, in order to flange the smallest heads, you have to off-set the upper center post.  It is difficult to describe this, so I’ll try to illustrate the point.

flanging machine center post (2)

The bearing pack on the upper center post on this flanging machine is centered.  Here is a close-up view.

flanging machine center post (3)

See how the flat oblong blue plate the bearing pack is bolted to extends to the right, toward the machine controls.  For the smallest heads this machine can run, the bearing pack can be moved to the front, or the right side, of the blue plate, so the center post can fit even more snugly up against the spinning icr roll.  Now it’s difficult enough keeping no-hole heads centered when the bearing pack is centered, when the pressure exerted by the upper center post is pushing straight down on the bearing pack which is making contact with the spinning head.  But when you have to off-set the bearing pack for a small head and the center post is no longer pushing straight down, but instead is pushing down on the back edge of the bearing pack, it becomes much more difficult to keep these heads centered.  Add to that a thick head.  Add to that a poor press job.  Add to that the fact that our flanging machines aren’t the newest, are in fact pretty worn out.  And it becomes extremely difficult to run small thick badly-pressed no-hole heads.  You are constantly spinning the head, stopping to re-center it, then spinning some more, then stopping to re-center it again.  You get the point.  That is why I called it the dreaded no-hole.

But that is why we are paid a decent wage.  If anyone could walk in off the street and do this stuff, then we wouldn’t be paid as much.  There are tricks to running no-hole heads that you can only learn the hard way, by doing it over and over.  I’ve learned never to move a no-hole head while it is spinning.  I’ll spin the head, stop, move it to where I want it, then start spinning it again.  It takes more patience doing it that way, but it’s easier and faster than constantly stopping to re-center the head.

This was the kind of problem that would make Badeye take a hammer to his machine.  But I’ve learned to let it go.  Just like the song.

frozen

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