Combining multiple machines into a single unit is a great idea -- but it results in some daunting design issues. Trying to fit everything into the smallest possible package poses unique challenges. When Miller Electric Mfg Co began development of the Miller Big Blue® Air Pak™, the company turned to RB Royal Industries of Fond du Lac, WI to help solve some of those problems.
The Big Blue® Air Pak™ is a first-of-its-kind machine that combines a welder, generator, and air compressor into a single portable unit. Fluid transfer design -- essentially, the "plumbing" of the machine -- proved particularly challenging. Size of fittings, material selection, and the actual configuration of the fluid handling system all had to be taken into consideration. To resolve these issues and help ensure that fluid handling was properly integrated with the overall machine design, Miller contacted RB Royal Industries, experts in fluid handling applications.
Multiple challenges had to be addressed. Because the unit is designed to be portable, space for fluid connections was at a premium. At the same time, the connections had to stand up to rugged use and transporting of the machine. RB Royal also had to take into account heat and vibration generated by three functions in close proximity to one another in an enclosed space. Of course, the connections also had to be practical to manufacture and economical to produce.
Working closely with Miller, RB Royal engineers made sure their solution met the constraints of the project and was compatible with the overall design of the machine. RB Royal engineers actually became an extension of the Miller design team, saving considerable time and reducing duplication of effort and excessive travel during the development process. Miller actually delivered a prototype Big Blue to RB Royal''s new 3,000 sq ft Product Development Center (PDC) -- a competitive advantage when time to market is critical. The PDC, with its dedicated equipment, allowed Miller and RB Royal engineers and technicians the opportunity to work on project modifications in real-time rather than waiting for production machinery to become available.
RB Royal approached the project by creating prototype assemblies to fit into the actual unit. The engineering team determined that custom metal tube assemblies were appropriate for fluid paths between two fixed points or on mounted components that were adjustable during assembly of the machine by Miller. This provided the rigidity, precision, and durability required by a portable, heavy-use machine. Custom metal tube assemblies also were used to protect fluid paths from high-temperature surfaces where hose assemblies could prematurely fail. Custom metal tubing assemblies were also vital in the development of a remote oil filter application to make it easier and safer to service the unit, thereby creating value -- no more reaching under or behind the engine to remove and replace the oil filter.
The end result is shown here. RB Royal''s custom-designed tube and hose assembly acts as an insulator against the engine''s vibrations. The flexibility of the hose provides relief from tolerance stack-up. Corrosion-resistant stainless steel tubing is used (upper left) to withstand the sometimes harsh environment within an enclosed engine compartment. The U-shape configuration is needed to trap the oil, preventing it from draining back into the engine. This stabilizes the level of oil in the engine, allowing the operator to get a more accurate reading of the oil level when the engine is in the stopped position.
"RB Royal became a part of our engineering team," says Joe Gitter, Miller''s project technician, Industrial Engine Driven Products. "Without their design expertise we would have had great difficulty in making our milestone dates on this project."
In applications where point-to-point tolerances were tight, RB Royal engineers determined that custom hose assemblies or hose/tubing assemblies were the best solution. Flexible hoses also were used in applications where vibration was an issue.