Rotary fan feeder machine design delivers high speed, small batch accuracy
As one of the world’s largest producers of adhesive bandages and suppliers of wound care products in both the medical and retail markets, Aso, LLC (Sarasota, FL) can now box up bandages faster than ever with a new rotary fan feeder machine designed by the company’s in-house engineering group. They also have the flexibility to run small batches of product with the same quality and accuracy as larger batches, and at the same high speeds.
|Aso’s rotary fan feeder runs so well it allowed the company to remove unnecessary equipment from its packaging line. Source: Bosch Rexroth|
Aso set out to design a rotary fan feeder machine to increase the speed at which bandages are cut, or “burst,” and then boxed. Essentially, the rotary fan feeder design they created is a high-speed die-cutting machine.
An operator threads a perforated roll of sealed bandages into the feed station and onto a large reel where they are registered and then cut into groupings based on the recipe data for the packaging requirement. The cut bandages are dropped into the cartoner machine conveyor from the fan feeder. The cartoner machine then puts the bandages into a carton or box. Small batch counts can range from 20 to 60 bandages per drop carton. Bandage sizes range from 3 to 3
In addition to running different bandage styles, the fan feeder can group and separate the bandages in different numbers. What varies is the batch count, which is the total number of bandages that are dispensed into each box. For example, if there is a batch count of 12 bandages, the operator would run a six-double configuration. If there is a batch count of 30 bandages, the operator would run a 15-double, and so on.
Biggest challenge was support for high speed
|The VCP 25 compact operator terminal is a touchscreen HMI that displays product recipes, machine status, and set up parameters for the batch and bursting action. Source: Bosch Rexroth|
Previously, the “bursting” section of the line would feed the cut bandages into an indexing machine used for packaging assorted orders and then move on to cartoning. Now, the indexing machine can be removed entirely from the line because the bursting speed of the servo-driven fan feeder can keep pace with the speed of the cartoning portion down the line.
The fan feeder operates 30% faster than the original machines. Now Aso can produce short batch runs more efficiently for various customer requirements. They can also run assorted packs about 20% faster than before, and the non-assorted even faster.
The speed at which this machine operates was very challenging for Aso. From an automation standpoint, the machine consists of two axes driven by Rexroth IndraDrives with MSK motors, a Rexroth power PC (PPC) running VisualMotion software, and an IndraControl VCP operator interface. Rexroth engineers worked closely with Aso and Gulf Controls to size the servo motors according to the move profile, as well as to develop the move profile itself. Sizing for the application was particularly important due to the incredibly high speeds needed.
“The move profiles they wanted were on the order of 26 ms per move,” said Chris Cooper, Rexroth sales engineer. “Most of the competitive products Aso had considered used up a majority of that 26 ms just for communications. After receiving Aso’s desired move profile, we went through several calculations and sized the motor for optimal performance in the application.”
Today, run rates are so high that Aso will not stop the line during production. In fact, the fan feeder runs constantly through two shifts. Instead of stopping the machine for errors, the machine simply rejects the bad section of the roll marked during a previous process, and the rejected product is dispensed into a chute along the side of the machine.
Working together, Rexroth and Gulf Controls enabled Aso to commission the fan feeder in a very short period of time. Programming, setup and testing of the machine required about 10 days for the first machine and two days for a second machine. Using Rexroth IndraLogic along with the IndraDrives also permitted Aso to reuse certain portions of their tested PLC/motion code for other applications, thereby further reducing the development time.
To design their new rotary fan feeder machine, Aso engineers used application support from the Bosch Rexroth Corporation Electric Drives and Controls unit and their distributor partner Gulf Controls (Tampa, FL). Aso used Rexroth components along with a critical motion profile to give the machine lightning speed.
The fan feeder’s building blocks
The Aso fan feeder measures a 52 in. deep by 36 in. wide by 60 in. high. The Rexroth IndraDrives on the fan feeder provide a power range from 1.5 to 75 kW with maximum currents from 11 to 210 A and a direct mains connection up to 500 V. The MSK servo motors also feature compact construction with increased torque density. The VisualMotion system supplies the control and drive requirements using an open-architecture control structure providing support for standardized busses to integrate into Aso’s existing systems. Centralized logic functions with analog and digital periphery take the place of an additional PLC. Instead, the PPC functions as the PLC to provide motion and logic control.
The VCP 25 compact operator terminal is used to initiate specific functions in the machine. For example, the HMI displays product recipes, machine status, and set up for the batch and bursting action. From the touch screen HMI using VisualMotion, the operator selects the recipe for the current product being run for the work order and loads the new roll onto the feeder. Maintenance and engineering personnel can also make adjustments as needed or set up a new product with new recipe parameters for the bursting action. The only other requirements for the operator are occasional side guide changes for certain recipes.
– Edited by Renee Robbins , senior editor
Control Engineering News Desk
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