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Bending/Folding

Complex bending

By Lynn Stanley

Keech Steel Corp. pairs bending experience and technology to grow its fabrication business

September 2011 - Iron ore harvested from mines and other underground sources is melted at high temperatures then poured into molds or extruded to form the steel sheets and plates consumed by contract and job shops. Transforming the hard alloy into high-quality goods can take years of skill and practice.

Jim C. Keech and his sons, Kevin and Jim Scott Keech, pooled nearly 90 years of experience with the metal and its derivatives and opened Keech Steel Corp., Salt Lake City, in 2005. The fabricator rolls, bends, welds and machines carbon steel, 300 and 400 series stainless steel, and aluminum into superior products for the mining and water purification industries and nearly every market in between.

In 2010, the trio matched their knowledge about steel with a JMT AD-S series 4-axis, 440-ton press brake to bring bending operations in-house to improve quality and control over delivery further. Technology features like a CNC-controlled backgauge and crowning system have helped escalate the company’s growth by allowing it to perform complex bending of large parts and unique shapes.

JMT, Salt Lake City, offers new fabricating and sheet metal equipment. The company’s in-house service and parts departments have more than 100 years of combined experience for repair and tooling needs.

Understanding steel
In addition to fabricating its own products, Keech Steel performs bending operations for other customers. Able to form nearly any geometric shape in material up to 11⁄4 in. thick, the fabricator primarily uses air bending with some bottom bending.

Understanding the characteristics of steel is an important first step. “Steel is like people. Each is a little different,” says Jim Keech, president of Keech Steel. “Different grades of steel can contain variations that include things like soft and hard spots. Our job is to adapt to the material to make it as uniform as possible and then monitor the metal to make sure it’s being processed correctly.”Understanding how the material reacts under pressure and how it will impact dies is also important.

The tensile strength and yield for carbon and stainless steel tells the operator how much tonnage is required to bend a part as well as the degree of bend. Plugging those and other critical parameters into the press brake’s Delem CNC control completes the equation, making it possible for the operator to perform complex bends.

Since installing the press brake, Keech Steel has used its technology to aid in the shaping of parts like the propeller shafts and blades found in powerhouses used for water purification. The 80-ft.-long shaft is made from steel pipe 1 in. thick, 20 in. in diameter and weighing 209 lbs. per foot. Keech Steel takes 1-in.-thick steel plate measuring 6 ft. by 8 ft. to bend and shape curved blades that look like the beaters for a mixer. Flat steel plate is loaded into the press brake at a skewed angle. The machine’s backgauge system positions the metal as the operator presses both a fade and a cone shape into the material at the same time. Multiple bends are required to complete the propeller, with the backgauge moving automatically between bends to check and control the position of the piece.

Accurate, quality parts
“The repeatability of the machine is unbelievable,” says Jim Scott Keech, vice president of Keech Steel. “It’s difficult to get a precise bend with thick plate. Our ability to make a quality part that is accurate is driven by the accuracy and quality of the press brake’s valves and cylinders along with support from the control.” Equipped with optical sensors, the control provides the operator with real-time data about the bending angle during the bend cycle, allowing the operator to make adjustments during the bending process.

The machine’s cylinders are designed to operate independently. The left cylinder functions on a Y1 axis and the right cylinder on a Y2 axis, making it possible for the operator to perform stage bending, cones, fades and transitions. The backgauge is equipped with an R and Z axis that allows the operator to gauge off difficult shapes like flanges. Once steel is cut to length, the flat shape is placed on the bed of the press. Backgauge fingers move up and down keeping the material steady by intersecting the shape at the best possible position.

CNC-controlled crowning also aids in bending long, heavy steel sheets or plate. “CNC crowning controls ram deflection,” says Matt Moore, national sales manager for JMT. “When you are bending long, heavy steel sheets, the ram, located in the middle of the machine between the two cylinders, deflects. CNC crowning counteracts this deflection by allowing the bottom of the machine to move up or crown as the ram deflects so that the bend shape is maintained. This feature also supports a fabricator’s ability to bend as many different shapes as possible in a variety of materials, a key factor in making bending operations profitable.”

Tanks, another bending operation that requires accuracy and repeatability, represent one of the most complex jobs for a fabrication shop, according to Moore. Typically, the product requires three cylindrical shapes, formed through bending and rolling, stacked and capped by a cone. During assembly, each level has to match perfectly. If the bending is off even a degree, the sections won’t line up during welding and the product could be scrapped. “It’s a one-time shot,” says Jim Scott Keech. “You have to be accurate the first time.”

Bending a cone shape for a tank or other application requires a precise backgauge and ram depth. To create the shape from flat steel plate, one side of the ram must penetrate deeper than the other side. If one side of the cone is 12 ft. long and one side is 4 ft. long, making a 360-degree circumference requires 10 36-degree bends. “It takes years of experience to bend a cone shape properly and quickly,” says Jim Scott Keech. “With the machine’s control, I can program the press and just keep hitting the stop. The machine automatically moves allowing me to perform any angle or number of bends a customer requires.”

The control gives the operator the ability to draw a shape or part while it calculates bend radius, stretch out, blank length and other parameters. “We’ve basically eliminated the need for a drafter, an engineer and a mathematician,” says Moore. “The control performs the trigonometry and bending calculations.”

Training on how to use the control has optimized Keech Steel’s ability to take on a wider range of complex bending. “The training and support we received from JMT has allowed us to pursue very difficult jobs and produce good parts efficiently,” Jim Scott Keech says.

Since installing the press brake in 2011, Keech Steel continues to marry its knowledge about steel with its press brake technology to perform difficult bend profiles for products that meet customer specifications. “In the last six years, Keech Steel has grown in ways that are unbelievable,” says Moore. “The jobs Keech Steel performs are very specialized. Not just any manufacturer can handle that type of work. The company is one of the most respected facilities in the western U.S. and the main reason for that is people know they can count on Keech Steel to turn out a great product. One of the ways they do that is they are willing to make the investment in very high-quality machine tools.” FFJ

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Sources

  • Keech Steel Corp.
    Salt Lake City
    phone: 801/270-5415
    fax: 801/270-5771
    www.keechsteel.com
  • JMT
    Salt Lake City
    phone: 801/493-0151
    www.jorgensonmachinetools
    .com

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