Novel tube bender boosts tubular part fabricator's productivity

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A rotating-head tube bender is accelerating the production of complex parts at one of the USA’s leading tube and pipe bending fabricators.

The new Unison machine is installed at Sharpe Products of Milwaukee. Its rotating head action allows it to make left-hand and right-hand bends in one continuous cycle – doing the work of two of Sharpe’s previous hydraulic tube benders, while also speeding throughput by up to five times. This performance is enabling Sharpe to reduce the lead times significantly on a wide range of complex multiple-bend jobs, as well as on parts requiring bends of widely different radii.

Unison’s North American partner Horn Machine Tools supplied the new machine to Sharpe. It increases the number of Unison machines that Sharpe operates to three, and follows Sharpe’s long-term strategy to gain control commonality across its tube fabrication operation by progressively replacing old machines with Unison’s all-electric tube bending technology.

This approach has major time and cost-saving advantages. Operators only need to be trained to use a single type of machine, and can then be deployed wherever they are most needed within the company. Sharpe is choosing to standardise on Unison tube benders because they have proved to provide the performance that the company needs to maintain its competitive edge, and because it has found Unison’s support service to be second to none.

Sharpe’s latest machine is a Unison 2-inch (50mm) Breeze-Revolution tube bender that performs both left-hand and right-hand bending. The machine has two multi-stack tool heads mounted on opposite sides of a rotating frame. After bending using one or more tools on one head, the head retracts and a combination of transverse and rotational movement then positions the other head for subsequent bending operations. Changeovers between left and right hand bending heads can be repeated as many times as needed, allowing complex shapes to be fabricated completely automatically without removing the tube or involving any other machines.

Flexibility and speed

Sharpe’s President, Paul Krickeberg, says: “The flexibility of this machine has to be seen to be believed. A lot of the parts we produce, such as exercise machine frames and architectural handrails, are manufactured from standard 1.5 to 2 inch tubing and require a mix of small and large radius right- and left-hand bends. Until now, we have used two hydraulic benders – one for right-hand bends, the other for left-hand bends – which could involve up to three separate machine cycles and easily take five or more minutes. The Unison machine creates all the bends that are needed in a single cycle, and typically in less than a minute.

“What’s more, by replacing the two hydraulic benders with a single compact machine that can handle right or left bending we have gained valuable production floor space, which is always at a premium. The configuration that we ordered is capable of roll forming as well as rotary draw bending, so we can create large radius bends or tight radius bends down to 1D without changing machines.”

All Unison tube benders use precision software-controlled servomotors for movement control and feature fully automatic set-up, enabling them to be configured for new batches very quickly. They can typically be set up in about a third of the time of a hydraulic bender and provide very tight control of the bending process, enabling parts to be manufactured right first time, or immediately after producing a single trial part.

Sharpe has extensive experience of Unison all-electric tube benders – it has used the company’s 3-inch and 5-inch (76 and 130mm) machines for many of its operations for a number of years – and is very pleased with their performance and reliability, as well as the level of support provided by Unison. The machines are also popular with the workshop staff, who find them easy to set up and operate.

All three Unison tube benders are connected to an automation network. The first trial tube of every batch undergoes detailed examination by Sharpe’s quality assurance department, using a computer-based tube inspection machine. The machine compares measurements obtained from the trial part with those of the intended design, and sends any necessary correction data to the appropriate bending machine. Sharpe also intends using the network for downloading data from its CAD systems direct to the bending machines, to further speed design-to-manufacture.

Springback measurement and correction

The 5-inch Unison tube bender is equipped with Unison’s laser-controlled springback measurement and correction system, which was fitted retrospectively in 2012. This ensures bending precision by automatically compensating for the natural tendency of metal pipes and tubes to spring back slightly after being bent.

Paul Krickeberg says: “Customers are increasingly demanding very accurate parts and very fast delivery. Unison’s springback correction system provides us with a powerful competitive advantage, by enabling us to bend to an accuracy of one-tenth of a degree. We are about to ask Unison to retrofit this system to our 3-inch bender.”

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