Coil handling as a fine art for demanding customers
Above: The cradle (foreground) and straightener for a Colt Automation 26-inch, 20,000-pound heavy blanking line. This equipment handles coil up to 0.40-inch thick.
Coil handling as a fine art for demanding customers
March 2016 - The automotive industry can be a stern taskmaster. It is famous—or notorious—for its high quality requirements at the lowest possible cost. Throughout the process of producing parts and components, zero defects are the norm.
Take stamping for example. In addition to repeatable tolerances, the metal surface must be blemish-free. That is especially true of Class A material used for exterior panels and closure components.
For 50 years, Colt Automation has dealt with these accuracy and surface requirements. The Mississauga, Ontario, company is a tier 2 supplier that builds and integrates automated coil feeds for stamping press lines.
Its capabilities range from low-tonnage, stand-alone presses up to the heavy hitters, including transfer presses and tandem lines. Strip widths are from 6 to 84 inches, gauges from 0.02 inch to over 0.50 inch, and a maximum weight of 30 tons. Feed lengths range from a few inches to 6 feet and up. Colt’s customers stamp components from small electrical and electronic parts to exterior body panels for automobiles, snowmobiles and personal watercraft.
The infeed end of a peeler/threader unit with a seven-roll straightener. Capacity is coils up to 48 inches wide and 30,000 pounds.
Time of transition
Producers and processors of steel products are adapting to advancements in chemistry, mechanical properties, tensile strengths and more. Commodity cold-rolled steel continues in use, but this is the era of building press feed equipment that is compatible with high-strength, low-alloy steels. Stampers are running HSLA metal in the 80- to 90-ksi range, and mills are indicating that 120- to 130-ksi materials are in the offing as vehicles shed additional weight. Press feed equipment must adapt to these materials.
“For a slow-moving industry, [automotive] is evolving relatively quickly,” says Stuart Cordrey, Colt sales manager. “The automakers are all trying to make their vehicles stronger and lighter. The metals are getting thinner, but much stronger.”
Four components make up a typical press feed: An uncoiler, straightener, threading table and feeder. Cordrey is careful to call the flattening machine it supplies a straightener. “In Europe,” he says, “all flattening devices are called ‘levelers.’ In North America, we make a distinction.”
Colt’s straighteners typically contain seven to nine work rolls. A leveler may have as many as 21 work rolls, each backed up with three to four additional rolls.
“The leveler removes coil set, edge wave, crossbow and center buckle,” Cordrey explains. “Metal to be fineblanked is usually leveled because it must be absolutely flat. Our straighteners remove coil set, edge wave and some crossbow. Coil set is the biggest problem our customers have when feeding a strip into a press.”
Colt doesn’t measure flatness in I-units; it specifies flatness per unit of length. The company claims flatness within 0.0001 inch per linear foot.
Smartest machine in the room
The feeder mechanism is integrated with the press and is the most intelligent component in the feed line. “The feed has more to do than simply supply a certain progression of metal into the press,” Cordrey notes. “The feeder also detects problems and notifies the operator.” Simulation software is built into the feeder so the operator can preview how the feeder will react in fault situations. “You can’t say the feeder is a slave to the press or the press is a slave to the feeder,” he adds. “The two work hand in hand.”
Allen-Bradley and Bosch supply some of the controllers Colt incorporates into its feed lines, but they do so with a difference. Most builders, Colt says, use a standard control package. Colt opens up the programs to offer additional features, such as press simulation.
With servo-motor drive, feeders have become extremely accurate and repeatable. Colt maintains accuracy on each feed progression of 0.003 to 0.005 inch, regardless of feed length.
Controlling movement of the coil end preserves surface condition, and aids operator safety. Process rolls in both the straightener and the feed are 52100 aviation-grade alloy steel. The rolls are cylinder ground, flame hardened and flash chromed to a Rockwell hardness of 60 to 64, to prevent pickup of metal shards that could mark the metal with each roll revolution.
The peeler/threader unit from the previous page, shown from the feeder end. In the center, between the straightener and the feeder, is a bomb-bay style threading table.
Four-fifths automotive
Eighty percent of Colt’s business is automotive, with the remaining 20 percent including battery plate manufacturing, perforated fencing and plastic erosion barriers for the construction industry.
Erosion barriers are a special application, according to Cordrey. The plastic strip feed is 72 inches wide and very high speed. “The feed has polyurethane rolls and runs at over 200 feet per minute,” he says. “The feed swings away from the press like a door when the customer wants to run parts without it.”
Another growing market is battery plates and separators, courtesy of the dynamic demand for hybrid and electric cars. And the value of the Canadian dollar is a boon to Colt. “The market is on fire,” Cordrey concludes, “and it’s going in a fantastic direction for us.” MM
