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Coil Processing
Monday | 27 October, 2014 | 1:06 pm

Coil automation: Where we stand

By J. Neiland Pennington

Above: The 32-foot stretcher section and operator’s stand at Butech Bliss’s coil line at Feralloy in Decatur, Alabama. The line runs 100-ksi steel up to 72 inches wide by 1⁄2-inch thick.

Examining the current state of computer and quick-change technologies

October 2014 - Controlling metal processing by seeing, measuring, reacting, manipulating and correcting is made easier on equipment operators via automation. One expert on coil processing equipment likens the work on automated lines to playing computer games.

Automation in the coil processing industry is nothing new. Starting some 30 years ago with programmable logic controllers, technology has progressed to microprocessor-based systems that are nearly ubiquitous today.

“We think automation makes the operator’s life easier,” says Al Waigand, vice president of sales and marketing for Butech Bliss, a coil equipment builder in Salem, Ohio. “An operator 30 years ago was pushing buttons for every function. Today, with the computer and the human/machine interfaces we use, operating a coil line is almost like a computer game.” Young people who grew up playing them are comfortable with technology and are adept at operating computerized machinery, he adds.

Waigand and Ed LeClerc, director of electrical and automation for the company, sat down to discuss the general state and nuances of automating these processes.

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Flatness detection

Butech Bliss developed a system of flatness detection and measurement trade named Hawkeye. A row of sensors across the strip takes measurements every 6 inches in increments of 0.001 inch to report flatness errors. Both ultrasonic and laser versions are available, and the Hawkeye can both display flatness data on a monitor and print out flatness reports.

Butech Bliss has a Hawkeye installation in which a sensor is mounted within a stretcher leveler. As the operator is stretching the material, he can see the change in shape. “The operator can run the stretcher automatically and monitor what the stretcher is doing. He can also run manually and stop the stretch cycle to decide how much stretching to do,” LeClerc says.

Control remains in the hands of the operator and the flatness sensors are not connected directly to the stretcher. “It’s not a closed-loop system [but] that’s a capability for future development. We need to accumulate more data on the manual installations already in operation before we have confidence in an automated system,” he says.

Six Hawkeye installations are in operation, three in full production and three in testing. Two production units are in the Southeast and one is in Mexico.

Dynamic width control

Butech Bliss builds side-trimming heads that position automatically when the strip width is changed. According to LeClerc, the operator doesn’t have to stop the line, which improves uptime and increases yield. As strip widths change, the trim knives turn in or out, and the steering of the knives is automatic. A notch or hole is punched in the strip to indicate to the knives when to adjust to a different width.

In addition to width positioning, the side-trim knives are automatically set for gap and lap. “We have the ability to set up the side trimmer because we know both the gap between the knife blades and the amount of overlap for each product,” says LeClerc. “When the operator enters the material that’s running, a program sets the knives.” 

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The program considers both the thickness and yield strength of the metal, and the operator can override the settings as necessary.

The machine builder has developed a system for calibrating roller levelers that eliminates having the operator manually insert gauging bars in the roll nest. 

The manual method is neither safe nor reliable, says Waigand. Use of a gauging bar is wholly “dependent on the fellow who’s doing the calibration and his interpretation of when the rolls are closed. With a gauging bar, you bring the rolls together against the bar and look for daylight. We have included the sensing equipment within our levelers [so] you bring the rolls together and control the amount of pressure that you have in the machine, so that anybody can calibrate and repeat the same results. 

LeClerc elaborates: “The problem with a gauging bar is that you can’t put a lot of force on it. Otherwise, you’ll bend the bar. With our system, you press a button and the rolls are brought together under a predetermined force so we have a very accurate measurement of the gap between the rolls. We use pressure transducers that monitor the calibration pressure.”

The predetermined pressure is the zero position for the sensors that measure roll penetration, and position sensors are accurate to 0.001 inch. The complete procedure requires about two minutes.

Remote technical support

No computerized system is fault-free, and the technology can create issues that not all coil processors are capable of addressing in-house. Butech Bliss’ answer is virtual private networks (VPNs) that link its technical personnel with customers’ processing lines.

“We sell our processing lines in many parts of the world,” Waigand says, “and by the time we get a technician there they’ve lost a lot of uptime. If they have an issue we can link them up with the right person 24/7 who can resolve the problem.”

There is another advantage of VPNs. “Usually, the person on the phone or online with the customer is the same person who installed and started up the line. So he’s very familiar with the system, and can diagnose a problem much quicker that someone at a remote call center. While the line is under warranty, usually a year, the service is free,” LeClerc adds. 

VPNs also facilitate preventive maintenance based on actual hours that equipment is used. Butech Bliss monitors various components and events in a line, such as the hours of hydraulic pump operation, the number of cuts a shear makes or the cycles a stacker runs. The line operator is flagged to indicate what maintenance is needed. The result: Downtime for maintenance in many cases is reduced and reliability increases.

Hand in glove with computer technology are techniques for speeding setups and changeovers on coil processing lines. One major contributor to increased uptime is levelers that include multiple work roll diameters in one cassette rather than having different cassettes with multiple roll sizes. Butch Bliss calls this new design the Synergy leveling system. The company also builds traditional hydraulic roller levelers with work rolls and backup rolls in cassettes that can be removed and replaced in as few as 10 minutes.

Each roll features individual, independent drives, with a variable speed AC motor, gear reducer and spindle for each roll. The conventional design is a single motor and a pinion stand driving all the work rolls, upper and lower. If one drive roll fails, a Butech Bliss line can continue to run until the motor is repaired or replaced.

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“The work rolls operate at slightly different speeds, LeClerc explains. “So the advantage of having individual motors is that we can accommodate these different speeds. If you have a single motor and a pinion stand, they are trying to drive the work rolls at exactly the same speed. You end up with roll slipping or windup and our system gets rid of all of that. Because we have separate variable speed drives, we create tension between each roll that aids the leveling process.”

With a single-drive motor, the work rolls could require 100 horsepower or more. But with individual drives, the requirement can be a fraction of that. A small leveler could have motors as low as 5 horsepower. Individual drive systems aren’t just for light gauges, either. Butech Bliss has levelers in the field that are running plate from 2.5 to 3 inches thick.

Adding intelligence

LeClerc likens computer technology to adding intelligence. “We are trying to put more intelligence into the control system so that it is easier for the operator,” he says. “Setting up the leveler, setting up the side trimmer, setting the knife gaps—we’re trying to make them more automatic.

“We do a lot of operator training, particularly at a greenfield site. Quite often, the people we train have very little operational experience. By having some of these features, it makes it easier for them to come up to speed.”

Consistency is an important product of automation, he concludes. “The line is always set up the same, regardless of who is operating it. A veteran of manual lines may pull out his little black setup book and run different settings. You can end up with potential quality issues. Not so with computer controls.” MM

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