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Two bending processes, two directions, four tooling sets, one machine

Fabricator invests in rotary/roll machine that makes left-, right-hand bends

If you bought a new car recently, you’re aware that the digital revolution is making more inroads into more areas every day. The technology that changed the way we listen to music, watch movies, take photographs, talk on the telephone, buy products, and dozens of other activities is changing the way we drive. It shows up in onboard cameras, collision-avoidance systems, and self-parking sensors. Using the Internet has become such an integral part of modern life that Wi-Fi is available on many models these days, even midrange cars and trucks.

Computing power and new technology are changing the options for tube fabricators in much the same way. Digital technology brought computer numeric controls (CNC) to manufacturing a generation ago, but the original CNCs are veritable dinosaurs already. Progress is swift and relentless in the hardware and software that run the modern world.

Meanwhile, as engineers’ tools become more complex, the products they conceive become more complex. Whether developing a bicycle or a motorcycle, a golf club or a golf cart, handrails or handlebars, designers strive to set their products apart from those of the competition, and one way to do it is with an eye-catching design. In today’s competitive market, tube fabricators are challenged by difficult design requests, and as always, they need to find ways to manufacture them efficiently. This is where new options driven by computing power and new technology come into play on the fabrication floor.

Over the last few years, Superior Tube Products Inc., Davenport, Iowa, noticed that requests for quote were becoming increasingly complex. A contract manufacturer that specializes in fabricated tubular parts and welded assemblies, Superior has decades of tube bending experience, so it knows a new trend when it sees one. Some of the more challenging designs these days go beyond merely making an assembly work.

“We think a lot of people are designing more for form instead of just function,” said Gus Griffin, tube bending supervisor. In other words, the aesthetic appearance is playing a larger role these days. In many cases, a component or an assembly has to fulfill a role and it has to look good.

Eventually company management realized that it would need to rethink its bending capability.

Bend, Bend, Bend, Crash

As part length and complexity increase, the process of making the part successfully becomes a greater challenge. In some cases, solving a problem is just a matter of changing the program that runs the bender. If a 180-degree rotation will cause a left-facing leg of a bent tube to strike the floor, bending that leg to the right in the first place will cause the leg to swing through the air, missing the floor and solving that problem. However, in some cases, careful programming isn’t enough. Depending on the machine, a part might be impossible to bend.

“In terms of being able to bend a symmetrical part, we were running into a lot of parts with a very narrow open-end width,” said Keith Niebur, the company’s general manager.

“In other words, when we tried to make the last bend or the last two bends, we’d encounter interference at the machine. The end of the tube would strike the bend head because we couldn’t swing underneath it,” he said.

“The ever-increasing part complexity requirements from our customers exposed the limits of our machines.”

The main limit was the bending direction. Conventional machines bend in just one direction, so avoiding an interference with the machine often requires the programmers to visualize the part in two separate bending sequences.

“On one particular 10-bend part, we’d make eight bends, then change the setup, switching it over to make the last two bends,” Niebur said.

Sometimes even this didn’t work. Superior found that a machine capable of bending in both directions, commonly called a right-left bender, opens up new possibilities.

“The bend head rotates, which changes the configuration of the machine,” Niebur continued. “It allows us to miss the previous bends that are already in the part ahead of the bend we’re trying to form.”

Draw It or Roll It?

Draw bending uses a draw die set with a clamp and a follower, and it bends the tube by wrapping it around the bend die. The die’s radius is the bend radius, so making a bend with a larger radius requires a larger bend die, but this has a practical limit. Eventually the bend die becomes too big and too expensive to manufacture. For such applications, fabricators turn to roll bending machines, which use three roll tools. They’re not suitable for small-radius bends, but excel in making gentle, sweeping bends. They also can make multiradius bends.

Large- and multiradius bends often are the basis for making aesthetically pleasing products and a critical element in staying in the bending game these days. The rub is that one component often needs a combination of small- and large-radius bends. What’s a fabricator to do? Making some of the bends on one machine, then transferring the part to a different machine for a bend or two, and perhaps going back to the first machine for the last few bends is a sure way to send the cycle time through the roof and drive the accuracy and the consistency into the basement.

Fortunately, Superior found a machine that handles both processes. It purchased two Soco model SB 32 9A 2Su CNC benders from Tube Forming Solutions LLC.

“These machines allow us to mount both sets of tooling on them simultaneously so we can actually do parts that have both types of bends in them without having to remove the part from the machine,” said Jeff Otten, another of the company’s tube bending supervisors. Changing from an interrupted process to a single process lowers the cycle time, improves the tolerances, and improves the consistency. It’s also safer. Less material handling means less risk of an accident.

Uptime Improvements

Modern tube benders have a few more tricks up their proverbial sleeve, many of which improve the machines’ uptime.

“The particular machines we have are two-stack machines,” Otten said. “You can actually stack two different sets of tooling on top of each other. Of course, this is a right-left bender, so each of the bending heads can hold two sets of tooling, for a total of four tooling sets on the machine at any given time.

“Often when you need the right-left capability, the bend radii are consistent so you’ll have identical tooling on opposite sides of the machine,” Otten continued. “However, if we don’t need that capability and we’re running parts that don’t have interference issues, we could have four radiuses in a single part and switch between tool sets seamlessly.

“The nice thing about having four different ones [is that if] the manager comes out and says we need this part right now, and it’s one of those sets, all we have to do is walk over to the controls, hit three buttons, and we’re ready to run that part,” he said.

“For a lot of our high-volume parts, the tooling remains in the machine if we don’t need to take it out. It’s just a matter of pulling up a program and loading it. It’s ready to go,” he said.

“The left- and right-hand benders are all electric, which makes them extremely repeatable,” Griffin said. “In terms of accuracy, throughout the day we are making no adjustments.”

The company uses some older hydraulic benders that have less sophisticated control technology, so any change in the process—a change in the hydraulic fluid temperature or finishing one batch of tube and starting another—requires an adjustment to the bender. Electric machines have servo-driven axes that have position monitors, so the adjustments are automatic.

“We can [also] hold tighter tolerances, which is a big deal to our customers,” Niebur said.

Finally, digital technology has the ability to interface with a network. When a problem arises, a technician can log in from a remote location to troubleshoot, make adjustments, and in some cases fix a machine without making a site visit. It also allows the company to back up all of its programs. Recovering from a controller failure is just a matter of installing a new controller and downloading the programs from the network.

About the Author
FMA Communications Inc.

Eric Lundin

2135 Point Blvd

Elgin, IL 60123

815-227-8262

Eric Lundin worked on The Tube & Pipe Journal from 2000 to 2022.