Put the Brakes on Proprietary Controls

AT A GLANCE

Faster, more open controls

PC-based flexibility

EtherCat Ethernet protocol

You don’t have to be a Fortune 500 CEO to know that few companies with “take it or leave it” strategies can succeed. As the number-one press brake manufacturer by machine volume in North America, Accurpress understands customer needs and isn’t afraid to make changes including to its control platform.

Accurpress has nearly 9,000 presses operating in the field, covering applications in the automotive, aerospace, and metalworking industries. At its design facility in Surrey, British Columbia, Canada, design engineers sought an open controls platform. The market, they say, is heavily saturated with “proprietary, as-is solutions.”

This line of press brakes includes three major offerings. The original Accurpress can achieve repeat press accuracies of

PC upgrades, circa ’01

In 2001, Accurpress R&D team leader, Alex Kvyatkovski—along with colleagues Alex Kapulnik and Oleg Voytkov—began a long-term initiative to upgrade the company’s high-end Accell machine line. At the time, Accell used a proprietary controller made by a company specializing in controls press brakes. While performance was considered acceptable, high cost and limited programming flexibility were seen as significant obstacles to maintaining a competitive edge, the company says.

“Most of the competition Accurpress sees in the high-end area comes from Europe,” Kvyatkovski says. “That led us to continue to look closely at European controls providers and do thorough research on emerging trends that fit the Accurpress vision.”

At the time, no press brake manufacturers were using open, PC-based controls. However, this is exactly the direction that seemed the most promising to Kvyatkovski. “Essentially, we were pioneers in uncharted territory when Accurpress decided to go PC-based. Some of our competitors in Europe ultimately followed suit, but Accurpress had no proper point of reference” about where to begin, he says.

After Gerd Hoppe from Beckhoff Automation gave a presentation on PC-based control architectures and that company’s TwinCat software, Kvyatkovski and his team decided to use industrial PCs for controls. Kvyatkovski liked how “one CPU could do everything—the entire machine’s motion control and run the HMI software. This was much cleaner and more cost-effective than the multiple-hardware PLC route. The system was also significantly less expensive than the original Accell third-party controller.”

Flexibility adds features

The Accurpress Accell design features a Beckhoff C6240 Control Cabinet PC with a 2.4 GHz Intel Pentium 4 processor and 256 MB of DDR-RAM and TwinCat NC PTP software for point-to-point axis positioning. Positioning is executed by TwinCat with an advanced algorithm, in which profiles are generated with jerk limitation and pre-control of speed and acceleration to minimize errors. TwinCat also is compliant with IEC 61131-3 from PLCopen. That global standard gives users five languages in which to write code. Accell features Beckhoff CP7037 Control Panels for the HMI hardware, with flat-screen, TFT displays and housings milled from blocks of aluminum.

Until recently, Accell machines had used Beckhoff Lightbus as the fieldbus network. “Because it uses fiber-optic cabling, Lightbus is very noise-tolerant and provides fast I/O processing,” Kvyatkovski says. Lightbus protocol has a compact telegram structure that permits user information data transfer rate up to 2.5 Mbits/s.

With a custom application that required faster response times than conventional fieldbus technology could handle, Kvyatkovski says Accurpress moved beyond Lightbus to the industrial Ethernet-based protocol, EtherCat. “Since EtherCat uses off-the-shelf, standard Ethernet hardware and cables, we’re confident this approach will be the most cost-effective. It will also help make our Accell machines even more repeatable by significantly reducing cycle times.”

EtherCat protocol is said to process 1,000 distributed I/O signals in 30

A recently added feature on Accell press brakes is the Sheet Follower system. This device, mounted at the front of the machine, handles materials too heavy for an operator to lift. Via an electronic axis, TwinCat synchronizes motion with the press and allows Sheet Follower to lift and lower heavy materials safely without slamming into stationary supports.

Accell also features an active angle measurement system, which measures material spring-back in the press brakes while the press operates.

CPU centralization is said to save Accurpress money and provide a clean and flexible architecture. Kvyatkovski says, “We’re able to customize according to almost anything a customer asks of us, something a lot of our competitors may not want to do.”

Today, Accurpress quickly, easily, and cost-efficiently develops custom features for customers using TwinCat software, often at the same time the company sells them. Shorter lead time (as little as two to three months for major customization) tops its competitors, Accurpress says. “With an off-the-shelf controller from a third-party vendor, this simply would not be possible and several lucrative machine orders would be lost as a result,” Kvyatkovski says.

“I know we made the right decision in the move to PC-based controls,” Kvyatkovski says; “We find that press brake users are seeking synchronized presses like ours, while traditional PLCs and proprietary designs are quickly losing favor.”

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