Skimming over the water at up to 110 mph, Diamondback airboats can cut through miles of water rapidly. Made from aircraft grade aluminum welded and riveted together, the boats need to be ruggedly built and designed to handle these top speeds. Diamondback Airboats (Cocoa, FL) has its own hull design, using different grades of T6 aluminum depending on the application.
"We started the company in November of 1989," said president Bobby Fleckinger. "Diamondback Airboats started out with just me, my mom, and dad. The first year we hired one employee -- now we have 50."
Located not far from the Kennedy Space Center and Disney World, the company now produces about 240 aluminum airboats per year in a 19,000 sq ft shop, to which an 8,000 sq ft addition was built in 2004. Previously, Diamondback''s productivity was limited by their old facility''s smaller size and the capabilities of the fabricating equipment. To produce their larger 30 ft airboats, they had to bend the hull in two pieces, then seam weld it together, which took 4-5 hours.
Once in the larger building, a search began for equipment to boost productivity and quality. A larger press brake was an important addition for the shop, according to Fleckinger.
"We checked many different brake companies," Fleckinger said. "We reviewed 4 different companies'' machines for capabilities, service, and pricing. After we analyzed all this information, we chose a Pacific Press Technologies, L.P. Fabri-K, 400 ton press brake with a 22 ft bed length."
With this new press brake, they were able to eliminate approximately 4-5 hours of welding for their larger airboats. But the press brake also gave them greater flexibility: the company also does custom fabrication work for airboats, boats, and swamp buggies.
Building An Airboat
Airboat hulls start out as a single sheet of aluminum (bigger boats require bigger raw material sizes). The piece is first trimmed to a net shape and prepared for bending. Bends are then made on both edges to produce the airboat''s topsides. Using 10 deg bends, a radius is formed that produces the hull shape and, by design, significant strength. After the brake bending work, and depending on the type of airboat ordered, stringers, ribs, transom, and decking are added to finish the hull. Next, the engine, electrical components, fuel tank, seats, and any other options are added.
With the new press brake and larger facility, Fleckinger said the company can grow without feeling squeezed again. "We actually tripled our size since we moved into this building. We just got a contract with Ski Nautique, for their fiberglass boat ski towers," he said.
Bending Versatility and Productivity
Pacific''s Fabri-K press brake is CNC controlled. "We put the airboat''s model number in the computer and the brake''s back gauge automatically moves the aluminum sheet around for bending. This makes it very user-friendly and easy to program," said Fleckinger.
Their Fabri-K press brake provides 400 tons of forming pressure and 264 tons of punching pressure. The ram and bed length is 22 ft with a 10 in. platen width. Throat depth is 10 in. and the height is 15 in. Maximum stroke, which is fully variable, is 12 in., and maximum open height is 20 in. Ram speeds in inches per minute are: rapid, 146 in.; normal, 25 in.; and fast return, 146 in. The ram''s repeatability and parallelism is +/- 0.001 in.
For control, the press brake uses an Electronic Servo Level and Depth Control System. Y1/Y2 ram axes are controlled through bed-referenced, high-precision optical linear scales. The distance between the ram and bed is monitored by the DNC operator control and measured on each side with a precision of 0.0004 in. This measurement is fully independent of the machine load, both on-center and off-center loads.
An Anti-Whip Circuit is also integrated to the press brake''s operation at Diamondback. When bending long pieces, "whip-up" can be very dangerous to operators and the resulting back bend can deform the boat hull. This circuit will decrease the speed of the ram to approximately 1/4 the normal pressing speed, thereby reducing the tip velocity of hull parts when forming. This prevents buckling due to inertia of the part, which often results in permanent set or reverse bend on the material. The anti-whip circuit is automatically activated during the last 1/8 in. of stroke or a selector switch is provided on the control panel to select the anti-whip feature instead of normal press.
Diamondback''s Fabri-K brake uses a pendant-mounted DNC 60 Control. It offers easy programming and high reliability, with LCD text display; automatic calculation of ram position, bending force, speed change points, and pinch point; programmable vertical and horizontal gauge finger movement (X & R axis capability); inch/metric programming; and a tooling library with 30 dies and 20 punches. Along with tooling nomenclature, the programmer can set safety zones and tonnage limits. It also utilizes automatic tonnage calculation and regulation based on tensile strength, vee die openings, material thickness, and bend length.