September 2012 / Volume 64 / Issue 9|
By Alan Richter, Editor
Bandsawing a structural workpiece, such as a steel H-beam, is challenging for the bandsaw blade. This is because as the blade enters the cut, it starts sawing the beam’s flanges before contacting the crossbar, or web. On average, each flange measures only about ½ " wide while the web might be 20 " wide.
Courtesy of Peddinghaus
When a bandsaw blade, typically made of HSS, cuts through significantly more material while processing one section of the workpiece than the rest of it, the feed rate must be decreased to extend blade life, according to Nick Hajewski, marketing manager for Peddinghaus Corp. The company supplies CNC bandsaw machines and other equipment for the structural steel industry. When the blade exits the area with more material, the feed rate should be increased for the remainder of the cut to enhance productivity.
To overcome this challenge, the company introduced Smart Saw bandsaw pressure-sensing technology to manipulate the feed rate without operator intervention. As the saw encounters a beam’s web, the technology almost instantaneously recognizes the increased stress the saw blade experiences. A proximity switch on the machine’s ballscrew feed system detects the increase or decrease in stress on the saw blade.
Hajewski explained that there’s a mechanical gap between the proximity switch and a pressure plate, and as pressure is applied to the plate—meaning more back pressure is exerted on the blade—the plate gets closer to the proximity switch. When the plate reaches a specific distance from the switch, the machine control receives a signal to reduce the feed. Then, when the distance increases while sawing through less material, the proximity switch is disengaged and the control restores the original feed rate.
In addition to reducing premature blade wear, Smart Saw technology minimizes blade breakage. It can take 10 to 20 minutes to change a broken blade, depending on its size, and around three or four cuts at a slow cutting speed to break-in the blade once changed, Hajewski noted. According to the company, the technology cuts blade failures in half.
Another benefit of the technology is higher cut quality. A blade that’s pushed too aggressively through a high-density section does not cut as straight and clean and the workpiece might require grinding to remove bow and burrs, Hajewski said. “Shop managers don’t want their people handling anything with jagged edges; they don’t want them cutting themselves on a section while moving it.”
For more information, contact Peddinghaus Corp., Bradley, Ill., at (815) 937-3800 or www.peddinghaus.com. CTE
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