Page 16 - MetalForming Magazine April 2023

Tooling by Design
Pilot-release timing offers another consideration. Servo- feed units relying on pneumatic cylinders to lift and close the feed rolls or grippers also must consider the delay time from when the signal is sent to open the feed and the actual time it takes to open. The time required to charge solenoids, activate switches, exhaust air from the pneumatic cylinder and pressurize the opposite side to lift or close the feed roll is quite small, about 35 msec, but can impact pilot-release timing significantly.
A press running at 55 strokes/min. takes an average of 3.1 msec for the crank to turn 1 deg. A lag time of 35 msec equates to 11.3 deg. of lag time, meaning that the pilot- release signal from the controller must be initiated at 11.3 deg. before the required roll-lift angle. Increasing speed to 65 strokes/min. means that only 2.6 msec is required for the crank to turn 1 deg., thus increasing lag time to 13.6 deg., which requires a corresponding signal change from the press control.
Increased press speeds can produce unexpected ineffi- ciencies when punches begin to chip due to high impact, when sensor faults allow the die to close on the strip, or when pilot pins do not position the coil strip accurately or distort pilot holes. Clearly, increasing efficiency involves much more than simply turning up the speed. MF
Protecting dies. Increasing uptime.
Sensors for
Modern Metalforming
■ Prevent die crashes by detecting faults before the die closes
■ Eliminate productivity loss due to maintenance/repairs and bad-part sorting
■ Verify work pieces, holding tools, stripper plates, pilot holes,
and more
■ Plan for the future with the help of an industry-leading IIoT expert
www.metalformingmagazine.com
MetalForming/April 2023 13