Page 20 - MetalForming August 2011

Coil-Line Upgrades
adjusts, taking the operator out of the equation—no need to stop and make adjustments. As a result, the metal- former now has an integrated system that will perform to today’s standards, thanks to replacing the brains, not the brawn, via plug-and-play electronic upgrades.
The preceding scenario can poten- tially allow a shop to increase press capacity by 30 to 40 percent. In many
cases, we’ve seen aging feed lines limit the performance of a fixed-speed press to running 36-in. stock at 27 strokes min. However, after upgrading as described above, the same press can run 56-in. parts at the same speed, without damaging the material. The operator need only stand by the press and collect parts. And, since the line is completely synchronized, all of the action occurs above ground, eliminat-
ing looping pits and their added expenses, maintenance and safety issues.
With all of these improvements made in the support equipment, the metalformer now can invest in vari- able-speed press controls to achieve even greater performance. The end result: Increased capacity and produc- tivity and improved part quality, with existing equipment.
Controls Improve Efficiency, Quality
Current servo-feed controls use a trapezoidal feed motion, which results in quick, jerky motions that tend to cause slipping and induce strain on the die and material, and potentially damaging the part surface. During the past 40 years, several attempts have been made to develop a profile mode to allow press lines to obtain smoother feed motions, including use of mechan- ical and programmable cams. Other attempts to smooth feed motion fea- tured the use of resolvers installed on presses, and servo-feed interfaces were developed to obtain integration and synchronization.
Now it is possible to operate in the profile mode using new electronic con- trols, without the need to install a resolver on the press. The key to the control system is its use of a selectable motion profile rather than a trape- zoidal profile, to provide a smooth motion and material feed while uti- lizing the full press-feed window. Since the quick, jerky motions are eliminat- ed, minimal stress is placed on the system’s mechanics and servo drive. This prevents die jams and material buckling while improving accuracy and reducing loop whip from payout equipment.
Based on the type of material, press and die being used, the operator can select from a choice of feed profiles that utilize the full feed window of the press. Once the press stroke rate, feed angle and profile type have been select- ed, the control system minimizes the stress transferred to the material, min- imizing the potential for marking. MF
18 MetalForming/August 2011
www.metalformingmagazine.com