Page 19 - MetalForming February 2011

compared to the more typical 12 to 15 strokes/min. Our engineers worked with Linear Transfer’s very accommo- dating engineering team to make it happen.”
As explained by Clark and corporate sales manager Terry Soanes, to allow the transfer press to run 50 percent faster than other transfer systems would have been able to run, Linear modified the cooling system used to prevent drives from overheating. Heavier-duty chillers were added to the control cab- inets, and “together, our engineering teams developed a counterbalance sys- tem to reduce the working load on the transfer system,” adds Clarke.
The counterbalance, now standard on certain Linear Transfer systems, is used on the lift axes to reduce motor RMS-torque requirements and extend ballscrew service life, which exponen- tially increases as load decrease. The pneumatic counterbalance-system pressure is monitored electronically and provides a warning for the opera- tor should the system move outside its set points.
Adding flexibility to the new transfer press, Linear designed a high-speed blank-destacking system for one end of the press to allow blank feeding. The design allows for coil-feeding operations from the opposite end, thanks to the ability of the destacker to accommodate part movement through a passthrough tunnel.
“We only blank feed about five per- cent of the time,” says Clarke, “to run odd-shaped parts such as boomerang- shaped control arms where the scrap rate would be too high with coil feed. For these jobs, we custom-blank inhouse and use the destacker to feed the transfer press.”
Two Transfer Presses, Three Bolsters
The second transfer press installed at Tillsonburg, in mid-2005, is a 2000- ton Eagle, also 96 by 256 in., rated to 22 strokes/min. The added tonnage allows the press to tackle the plant’s toughest task—a rear suspension frame of dual- phase 780 advanced high-strength steel
In mid-2008, Fleetwood installed this 1500-ton 96-by-256-in. setup transfer press rated to a whopping 60-in. pitch. The press boasts Linear Transfer’s newer transfer-system design, without the nose-cone structure (of the press on the previous page.) The new design drives the feed rails with belts attached directly to the rail.
www.metalformingmagazine.com
MetalForming/February 2011 17
(AHSS). Parts are 3 mm thick, 60 in. long and 20 in. wide, “and it takes every bit of 1600 tons to run that die,” says Clarke.
The two presses share three bolsters to enable quick changeover. The press- es face each other with a T-shaped floor-rail formation in between to accommodate bolster travel. The staged bolster, prepared with a die for entry into one of the two presses, also carries a set of transfer rails. As part of the die-change process—which occurs an average of twice per press per day— the operator installs the required set of transfer tools onto the rails. Once the bolster has moved into position at the press, the transfer system’s automatic coupling and decoupling feature enables quick and hassle-free trans- fer-arm installation. Also automated with each die change is shut-height adjustment. Die changes average 20 min. from last part to first part.
“One of the keys to efficient change- overs,” notes Clarke, “is the system we developed to quickly change the trans- fer tooling from job to job.” The firm purchases transfer tooling from the Pressroom Gripper Series (PGS) man- ufactured by Norgren (formerly Syron). The tools for each job mount perma- nently to a subplate. A series of holes drilled into the subplate allow the oper- ator to quickly locate it onto the trans-
fer rails by sliding the holes over per- manent dowels attached to the rails.
PGS grippers are available with reg- ular, chisel, flange, shovel and needle- nose jaw configurations, and feature (according to Norgren literature) one- bolt assembly to enable 1-min. recon- figuration. Fleetwood uses Norgren’s flange-jaw grippers when parts require a firm grip; otherwise, it uses its own inhouse-designed and fabricated shov- el-style tools.
Transfer Press Number Three
In mid-2006 the plant’s transfer- press lineup grew from duo to trio with the addition of a 1000-ton 84-by-210 in. Eagle press with a 48-in. adjustable pitch. This press is designed to tackle smaller dies that run at up to 30 strokes/min., stamping a variety of parts including sills, rear parcel shelves and flat floor parts.
“We designed this press similarly to the other two (with T-shaped floor rail to accommodate rolling bolsters), to be part of a two-press three-bolster cell,” says Soanes. “So, as our business continues to grow we can readily accommodate another press.”
In all, the plant runs about 70 trans- fer dies, each of which stays in the press long enough to run one week’s worth of parts. Run time averages three to four shifts to stamp parts for more