Modernizing a big press brake

Old iron is built to last. A new control system can help it last even longer.

A large press brake is a testament to metal fabricating’s might. These giant bending machines take on workpieces measured in fractions of an inch or even more than an inch. A lot of the work processed on these powerful devices requires multiple operators to complete the task. They are big pieces of equipment for big jobs.

A fab shop’s need for a powerful bending tool has always been a constant. That’s why you see vintage press brakes of 1,000 tons or more still in operation on shop floors. If these bending behemoths have been maintained according to the manufacturer’s specifications, they still can deliver the same forming power they were designed to produce when they were installed decades before.

As any metal fabricator knows, however, there’s always room for improvement. If that large press brake was installed within the last 30 years, it might be a candidate for modernization. A modern control upgrade can bring modern conveniences and benefits to a brake that already has the brawn.

In fact, press brakes from 350 tons and up are very good candidates for control upgrades because this type of retrofit is much more cost-effective than replacing the older brake with a new one. Smaller-tonnage press brakes aren’t as expensive, so the return on investment for a control upgrade for them isn’t as clear.

Cincinnati Incorporated faced this situation a couple of years ago with its 1,500-ton, 26-ft.-wide press brake. That giant was first installed in 1989.

Background on the Big Brake

The company uses the 1,500-ton press brake primarily to straighten plates that have been cut on the plasma cutting table. (The thermal energy introduces some distortion to the plate surface, and it needs to be flattened before it continues on to machining and welding.) The plate, which can get as thick 1 in., is fed through the center of the bending window, where the powerful ram taps the steel back into a flat state.

The brake also is used for precision bending, including a piece of 0.75-in., 22-ft.-long plate that needs to be within +/- 3 degrees of the specified bend angle—a pretty impressive feat for such a big part. In many instances, fab shops struggle with parts that large.

Accuracy is a main reason that metal fabricators should consider upgrading their large press brakes to the latest control technology. Cincinnati Incorporated shared that same desire, but modernizing the large press brake also gave the company the chance to formally work out an upgrade path from the old control technology to the latest PC version. Once that upgrade proved successful, the engineering team could reach out to the user base and offer the same modernization path for their large press brakes. If those fabricators keep their machines tuned up and lined up, they should be able to make good parts.

What else is a modern press brake control going to offer owners of a high-tonnage press brake? The shop is going to get the latest PC version of the control software, which brings all of the firewall protection that will keep the IT staff happy. (Show IT specialists a 10-year-old control and watch them cringe.) An upgrade brings the control software closer to what is being used on a shop’s other press brakes, which means that operators can fill in for each other on different brakes without wasting time trying to get used to a different type of machine control. In some instances, an upgrade means that a fabricator can finally program offline and actually store bending jobs, eliminating the need for a programmer or an engineer to recreate the job instructions each time the part is to be made.

The Retrofit Process

Cincinnati understood the benefits of upgrading the 1,500-ton press brake, but before any upgrade could begin, the team had to determine what needed to be done.

For any metal fabricator, the first step in the retrofit process is to run the machine to make note of any deficiencies. If the brake is underperforming in terms of accuracy, a technician can start troubleshooting to see if it is a control or a mechanical issue. The metal fabricator then can decide how to correct the situation.

After seeing what the brake can do, the fabricator needs to determine if it wants the brake to be able to do more. A very basic changeover to a standard PC control is possible. This provides real-time control over the bending action and some job storage.

More complex upgrades can provide for control over not only bending, but multiaxis backgauges, sheet supports, safety mechanisms, and angle measurement. The PC-based upgrades also open the door to networking, offline programming, and the ability to store jobs.

The Cincinnati team determined that a basic upgrade to the latest PC offering made sense because of the type of work the brake was mostly used for. Advanced features, such as angle measurement, aren’t yet available for these large machines, so a more basic offering made sense.

The manufacturer also updated the backgauge. This wasn’t a simple replacement of amplifiers, which are the components that will wear in a backgauge over time. This retrofit includes amplifier upgrades, new encoders, and new motors. Now there’s no doubt that the backgauge is on time and in position for the bend with the new digital control.

The large press brake had a rear plate support with rollers that also had to be addressed with the control upgrade. The support system was being looked at as a possible addition to the standard press brake design for other large Cincinnati press brakes when it was added several years ago, but that new feature was never commercialized. Nonetheless, the control did need to address those supports as well.

A new control can deliver accuracy only if the information provided to it is accurate. If a new tooling library is part of the new control package, a fabricator needs to know the actual dimensions of the tooling being used. Accurate dimensions help to turn expectations of accurate bending results into reality.

As part of this investment in the high-tonnage press brake, the company also invested in new precision-ground tooling, which has made a world of difference in delivering accurate bending results. It also forced the forming department to take a look at older tooling made by craftsmen over the years; gather the tooling’s actual dimensions; and do some maintenance, such as repairing a punch that may have lost the radius on its nose.

The End Result

As part of this entire upgrade process, Cincinnati also removed the ram from the machine and remachined the clamp to deliver a greater degree of parallelism. Now the brake has a parallel spec that is +/- 0.007 in. across the entire width.

Today the press brake is operating more efficiently than before the upgrade and producing more accurate parts. The bending department also has found a new level of productivity, with operators moving easily from one brake to another now that all the machines are using the same control technology.

With the introduction of some more complex parts, the bending department has re-established the practice of programming all the press brakes offline. The company had gotten away from that because, frankly, some of the operators were so efficient in using the old control technology to program the jobs that an engineer wasn’t needed to do the work offline. The introduction of the new control on the press brake provided an opportunity to take programming off the shop floor. This let the operators focus on bending, and the results are a tighter process and better parts.

A timely press brake upgrade, new tooling, and a more streamlined approach to programming and part production have resulted in positive results for Cincinnati. And it all started with that reliable piece of iron. It’s the same as the farmer with the 1960s-era John Deere tractor who decides that he wants to introduce a fuel injection system to it and replace the seat and steering wheel. That farmer can expect to be riding that tractor in the field for years down the road.

That retrofit package also is a foundation for another round of upgrades should the fabricator decide to add new features, such as a laser safety curtain. The latest control technology provides more opportunity for quick and easy feature additions in the future.

All in all, giving new life to an old brake might make sense for many fab shops. The three or five days it takes to follow through on such an upgrade is time well spent.