17 years ago
send a project a different direction; Basically inspiration to get off
the path that things are stuck in. I believe I've asked this before but
am re-addressing the issue as nothing has been resolved yet.
Here's the situation: We need to take a long 1/2" dia CRS rod, drill
the ends 1-1/2" deep x 5/16 and insert a 3" long hardened and ground
dowel pin in the end. The pin doesn't get much tension but gets some
torque in the form of tens of thousands of cycles over it's life.
Quantity is about 1000 ends a month so it's not enough to get really
fancy or a high investement (IE induction hardening a journal on
hardenable rod instead of using the insert). Cheap and servicable is
the order of the day.
We've tried using a hydraulic compression fit (heavy press in) which
held ok but didn't like the repetative stress cycling for long enough.
We've also tried perimeter welding the joint which draws out some of
the hardness (bad) and takes a little too much time. Currently, the
procedure is to cross drill the 1/2" rod with a small hole about an inch
from the end and plug weld into the hole and to the pin. This works OK
but there is a very small (5% or so) failure rate over time.
Any thoughts on a better procedure to use off the shelf dowel pins (or
whatever) and get the cycle strength we need? Other ideas? I'm just
trying to "break out of the box" here in my thinking. Labor needs to be
in the range of a couple of bucks per end.