Page 21 - MetalForming February 2014

To enable NSC to change dies using a tow motor, and to run hand-fed work in addition to transfer dies, HMS designed and built its transfer system unit to lift up and out of the way with an unprecedent- ed 130 in. of lift. Further, the NSC project team requested that HMS design the system with removable parking brackets with quick-change capabilities.
has ever built. This allows us to move a tow motor in to change dies, since the standard lift proved insufficient.”
Further, the NSC project team requested that HMS design the system with removable parking brackets and 400-lb. transfer-system crossmember with quick-change capabilities. The brackets secure the 400-lb. transfer- system crossmember. Typically, the parking brackets are static, mounted either to the press bolster or the tooling subplates.
“We needed the parking brackets to be removable,” says Zifferer, “to provide optimum access to the dies and enable hand-fed operations.” The press runs 75-percent transfer work, 25-percent hand-fed work—typically large stamp-
ings such as truck fenders run in batches of 1000 or so. To ensure that the cross- member can’t be released without the parking brackets in place, HMS includ- ed an interlock system. Sensors in the brackets signal that they’re in place before the crossmember is allowed to disengage and park on the brackets.
Increases in Press Speed and OEE, with Reduced Changeover Times
Repeatable part location is a defined goal of any transfer system, and as transfer systems age “slop shows up,” says Eisenbach. “While that press is rated to 20 strokes/min., we were lim- ited by the transfer system to running at 10 strokes/min. And, press uptime was restricted, as maintenance issues related to the transfer system caused numerous unscheduled outages.”
With the new transfer system in place, transfer jobs are running full speed ahead at 20 strokes/min. “The unit puts the parts in the same place every time,” says Eisenbach. “One place, the right place, the same place every time. Before, slop in the system required us to open up the fingers and guides to allow parts to be picked up. That slop has vanished.”
Also, press uptime has increased by
50 percent, “which helps contribute to the relatively quick return on invest- ment,” continues Eisenbach. “And we’ve also seen setup time on that press (last part off to first part on) cut in half. The tooling-bar packages are simpler to mount. Since we’re mounting dies using a tow motor, we no longer have to roll out the bolster.”
Attracting New Work
It’s always nice when retrofit tech- nology allows old dies to run better and more quickly. It’s icing on the cake when added capacity attracts new work that previously could not run on a press. Such is the case at NSC, thanks to the enlarged work envelope resulting from the HMS transfer system.
“The original servo-mechanical transfer system had a 60-in. pitch, a fixed 12 in. of clamp stroke and 12 in. of lift,” says Zifferer. “We specified the new transfer with the same amount of pitch, but with 30 in. of adjustable clamp stroke and 48 in. of lift. That added capacity allowed us to recently take on stamping of a large 48- by 48- in. base pan for intermediate bulk containers. The physical constraints of the previous transfer system pro- hibited transfer stamping of parts that large.” MF
www.metalformingmagazine.com
MetalForming/February 2014 19
Transfer jobs now are running full speed ahead at 20 strokes/min., double the speed possible with the previous transfer system. And, the new transfer system features 30 in. of adjustable clamp stroke and 48 in. of lift.