Stoughton, WI--For decades, the installation of wooden floors in semi-truck trailers has been a frantic, labor-intensive task. Crews of nine typically drill holes along chalk lines on the wood, hoping that the holes align with steel beams beneath the floor.

Unfortunately, the holes don't always align. Worse, crew members sometimes injure one another with the drills or simply cannot work in the noisy, enclosed environment of the trailer.

To solve those problems, one engineer has developed an automated truck-trailer floor drilling machine, which transforms the task of floor drilling into a simple, orderly procedure. Neil Waddell, director of automation and robotics for Stoughton Trailers Inc., designed and built the machine with the goal of drilling more consistent holes, saving on labor costs, and making the task more worker-friendly. "The manual method was crowded, hectic, and inefficient," he says. "We just wanted a method that would be completely automated."

To accomplish that, Waddell designed a system that combines sensors, drills, and driven wheels to find the steel cross beams, drill the holes, and move through the trailer. Known as the D-4 Dynamic Deck Drilling Device, it looks like a wide version of a floor waxing machine. It employs two 3.3-hp brushless Reliance Electric servo motors, a 100:1 gear reducer from Bayside Precision Gearheads, and a flexible coupling from Zero-Max to drive its two front wheels. The machine's rear wheels are driven off the same drive shaft by Gates Polychain synchronous drive belts.

During operation, the machine's drive wheels move it forward, while it employs Turck inductive proximity sensors to "look" through the wood floor and locate the steel crossmembers. When a sensor finds a crossmember, it sends an encoder count to a data register in a Control Technology Corp. Model 2600 controller. The controller, using predetermined offset values, then figures out how much farther the machine must drive to align the drills with the steel crossmember.

When the D-4 machine reaches its target, the controller signals pneumatic valves, which fire the machine's 24 drills. After the holes are drilled, the D-4 employs more inductive proximity sensors to determine the up-and-down location of the drills. When the controller "knows" that the drills are retracted, the machine advances to the next crossmember.

Waddell designed the D-4 so it can be easily transported back and forth on a powered cart between trailers on two separate assembly lines. Driven by a Baldor three-phase induction motor, the cart shuttles the machine to the next trailer, then raises it to the height of the trailer floor using a screwjack.

The resulting machine has transformed the frantic, nine-man process into a speedy procedure that requires a crew of just three. One worker controls the machine using a Quickpanel operator interface from Total Control Products, while two others install screws in the drilled holes.

For Stoughton Trailers, the technology has yielded a multitude of benefits. The firm expects to save about $1.2 million per year, mostly in labor costs. Drill bit life has also improved by a factor of 10, cycle times are shorter, and mis-drilled holes have virtually disappeared. "We have better-looking floors now, because the holes have been drilled straight and uniformly," notes Randy Gilbert, a second shift operator at Stoughton Trailers.

What's more, the system has helped create a more acceptable working environment. Peak noise level was cut from 113 to 82 dB inside the trailers, thus reducing the possibility of hearing loss or cumulative trauma disorders.

Equally important, the company's product is better. Angled and egg-shaped holes have been eliminated. "It's more accurate than the manual technique," Waddell says. "Our quality has gone up because of this machine."

Additional details...Contact Neil Waddell, Stoughton Trailers Inc., 416 S. Academy St., Stoughton, WI 53589, 608-873-2652.