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Keeping Parts On The Level

Nov./Dec, 2011

Don Begneaud, president of Begneaud Manufacturing, has tried every trick he knows to keep perforated, punched-metal parts flat.

Along with developing some proprietary ways to flatten them, he’s driven over them with a forklift. Run them through a bending machine’s pinch rollers, and when all else fails, he has sent jobs out to companies with specialized equipment to make parts flat. But after all these ways to do it, he finally came upon a system that guarantees flatness every time.

At the age of 14, Begneaud started his love affair with metal forming by welding together metal sculptures. He ended up selling them at art shows throughout Louisiana. What started out in the back of a pickup truck as a one-man shop with 6,250 sq. ft., evolved into a manufacturing campus with 12 acres and several buildings encompassing 100,000 sq. ft. Equipment includes lasers, punch presses and press brakes for precision sheet-metal production.

Getting parts level

One of the jobs that Begneaud did since 1990 was perforating sheet metal on his CNC-punch presses. However, when the metal was punched, it wanted to curl up towards the punch side, because the punch was shearing the metal and caused internal stresses within it.

Begneaud explains that on the hole’s cross-section within the material, it’s tighter on the top side rather than the bottom. On the bottom side of the hole you have blow out, and the top side the hole wants to shrink back to size. Therefore, when you’re perforating metal, it wants to curl upwards.

“Since 1990 I was doing perforated metals for the oil industry,” he remarks. “But it was mostly thin metal, so we developed our own proprietary techniques to level these metals after they were perforated. This worked fine for the thinner metals. But as we started getting into perforating more of the thicker metals, we found that it’s very tough to level out these types of materials, especially stainless steel.”

Some of the tricks they use to level a part are proprietary and other tricks are right out of the metalworking book mentions Begneaud. For instance, in punching the die can be shimmed up and an oversized stripper is used.

“But there’s only so much that we can do with these techniques,” remarks Begneaud. ”They have worked relatively well with thinner metals, but when we perforated thicker metals, that’s when curling becomes a problem.

“We were at the mercy of the customer accepting this inferior product. We would do things like roll over it with a forklift, or run it through the pinch rollers on our rolling system that did help produce a level part. However, it takes a lot of craftsmanship with this equipment to get a flat part, and it’s just a lot of hard work to do. It added a lot of production time to our parts.”

Periodically Begneaud would need to send his parts out to be leveled. It was extremely expensive, because they had short run products, and the companies that could do this service were hundreds of miles away.

“I ended up shipping parts from Louisiana to Tennessee to get my parts flattened which added considerably to their expense. Whether the customer wanted it or not, I had to add this leveling cost into the price, and sometimes I would lose the bid. So this was additional transportation, and these companies tended to charge me a lot to do the leveling.”

Faster leveling

As Begneaud wanted to increase his perforated sheet-metal business for the oil industry, he began to look at what was available to level these parts.

“I knew of a company that made a leveling system. In fact the company gave me a quote for a system years ago, but it was a little too expensive at that time. They gave me the names of companies that used its equipment, so I could use them to level my parts when needed,” he remarks.

After more research, Begneaud realized that a leveler was the way to go. This equipment could level a wide range of parts with varying thickness and sizes. Begneaud purchased an ARKU FlatMaster 50.

Along with getting all types of materials flat, ARKU’s FlatMaster 50 provides fast and easy cleaning with a quick-change system for the leveling rollers, user friendly operator instructions and fast memory input. The rollers that are used to remove any coil set or stress in the metal are designed in a cassette. While some leveling machines need to be taken completely apart to change or clean the steel rollers, the ARKU Flat-Master’s rolls are held in a cassette and can be easily slid out of the machine for service. Two bolts are removed, and the entire cassette containing all the rollers slides out from the machine’s side.

Other benefits

Another benefit that Begneaud noticed is that when the company was laser cutting a cut part, sometimes it would spring up from the heat induced into the cut and tension in the steel from coil set.

When Begneaud experiences this, they’ll shut down the process and run the material through the ARKU FlatMaster to relieve any stresses before they finish cutting the parts rather than doing it afterwards. By doing it beforehand they maintain the exact size and cut quality.

Begneaud mentions that they can level material thicknesses up to about 0.325 in. on the full 65-in. width of the machine. But they can level a thicker part if the width is smaller. They can level 0.5 in. thick material by not using the full width of the bed.

How it works

Roller leveling is a bending process where an unleveled sheet is deformed using a series of alternate bends applied by rollers mentions the company. Through this process, the sheet becomes flat and nearly stress-free. Sheet metal is passed between upper and lower sets of leveling rollers that produce alternate bends. Leveling rollers are offset by half the roller spacing in the direction of the part’s travel. Therefore, the sheet metal takes a wavelike path through the part’s leveler. The wave depth is greatest at the entry of the machine and smallest at the exit. The elastic-plastic alternate bends and the steady reduction in deformation produces a flat and stress-free sheet-metal part.

The FlatMaster’s lower leveling bank is fixed, while the upper leveling bank has only two parameters set: the entry and exit heights of the rollers. The gap between the leveling rollers produced by this method is critical to the leveling result.

If the gap changes during the leveling process, poor quality leveling can result. Therefore, hydraulic parts levelers, like the FlatMaster, are equipped with a gap-control system. If the gap between the upper and lower leveling rollers changes, the precision leveler detects this and produces a counteracting force within fractions of a second. Pressure is applied by powerful hydraulic cylinders at the four corners of the machine. The result is that a constant leveling gap is achieved at all times, even when the cross-sections change.

For thick parts the FlatMaster offers an additional advantage. Compared to mechanical levelers, hydraulic adjustments allow an effective overload protection. When leveling thick plates, high forces can occur on both the leveler and the sheet metal. An improper machine adjustment can cause several components of the leveler to be overloaded. But the FlatMaster has an overload system to prevent this.

ARKU Coil-Systems Inc.

Begneaud Manufacturing Inc.,