Plug-and-play zone-control boxes from Rockwell Automation replace pneumatic clutches and their associated devices in a new motor-controlled zero-pressure accumulation (MZPA) pallet conveyor from Alba Mfg. The result is a conveyor that can operate at elevations much lower than traditionally possible, and with reduced maintenance and installation time.
Many traditional conveyors use pneumatic clutches and chains to move pallets through a plant''s production line. However, these mechanical methods are less than ideal. Pneumatic clutches require air piping and constant maintenance, multiple devices drive up field wiring and programming costs, and elevations below 18 in. are impossible because of zone chains running underneath. The MZPA conveyor solves these problems by removing the pneumatic clutches.
"We wanted to introduce a feature-rich machine that eliminated the problems associated with pneumatic conveyors, while remaining affordable," said Tom Thomas, vice president of sales at Alba, an OEM based in Fairfield, OH. "The MZPA conveyor standardizes on Allen-Bradley® controllers that require less maintenance and training time because of operator and technician familiarity with Allen-Bradley equipment. As a result, this solution helps speed installation and lowers the total cost of ownership for end users."
In zero-pressure accumulation applications, pallets are coordinated with the rest of the line, moving from one zone to the next at just the right time, preventing a buildup of pallets and alleviating pressure on the flow of items through the process.
Controlling the application is a complete Rockwell Automation® solution, including Allen-Bradley sensors, motor starters, motor protection, panel connection system with cables, KwikLink™ with flat media, and an Allen-Bradley Bulletin™ 22ZC zone control system. Each zone uses an Allen-Bradley zone control panel that controls individual zone motors, eliminating mechanical and pneumatic components. Additionally, an Allen-Bradley power supply panel provides the 24 Vdc control power and the necessary interconnecting cables. All of the devices required on each zone are preassembled and wired within the zone control panel, which also includes all of the cable and connectors needed to interconnect the zones. Allen-Bradley KwikLink and flat media serve as the 22ZC communication medium, and the panel connection system serves as the ac line power medium.
The standard MZPA conveyor package includes key features such as adjustable time delays, "sleep" mode, and signals for flow control logic, which eliminate programming costs and increase reliability. Because the chains associated with pneumatic-clutch conveyors are eliminated, the conveyor can operate at heights as low as 5.75 in., compared to the previous 18-in. minimum height limit.
To ease costs for end users, the conveyor, along with its associated photoelectric sensors and DeviceNet™ connections, are plug-and-play -- ready for immediate installation. Accumulation logic is pretested at Alba''s factory. The installer only has to bring 3-phase power to the master power box, minimizing field wiring effort and cost.
"When designing this machine, we considered several options from various component suppliers," Thomas said. "In the end, though, we realized that standardizing on Rockwell Automation control technology simplifies our ordering process and reduces our learning curve and engineering time. For our end users, an all-Allen-Bradley solution means strong support and familiarity, giving them confidence in the system''s reliability and performance."
To ease the ordering process and reduce costs for OEMs, Rockwell Automation developed a kit that includes all the necessary parts for the MZPA conveyor.
"By creating a kit, it allows OEMs to tell us the basic specs -- for example, how many zones are on the conveyor and motor horsepower -- and we can send them simple kits that contain everything they need," said Jason Koehne, Rockwell Automation account sales engineer. "They don''t have to order everything one piece at a time anymore. It saves them both time and hassle."