Automation drives efficiency, lowers cost
Ever since Fernando Serpa began making end-of-line packaging machinery in 1981 for Serpa Packaging Solutions (www.serpapackaging.com), the company’s philosophy has been to improve upon its existing products. So when Serpa reintroduced its signature P200 balcony case packer, it turned to Bosch Rexroth Corp.
Jack Mans, Plant Operations Editor, Packaging Digest
Ever since Fernando Serpa began making end-of-line packaging machinery in 1981 for Serpa Packaging Solutions ( www.serpapackaging.com ), the company’s philosophy has been to improve upon its existing products. So when Serpa reintroduced its signature P200 balcony case packer, it turned to Bosch Rexroth Corp. ( www.boschrexroth-us.com ) to provide the product expertise and applications support for an integrated electric drives and control and linear-motion solution.
To help reduce costs and improve machine efficiency, Serpa also collaborated with local automation distributor Applied International Motion ( www.aimotion.com ) to specify and implement the Bosch Rexroth motion- and servo-control system.
Machine runs cases and trays
According to Serpa, the P200 is the first case packer to be able to run cases and trays on the same machine. The machine collates the product to achieve the correct pattern, loads the product into the case or tray and seals and discharges it. The servo-controlled erector motion has two camshaft profile axes that drive a parallel-link arm. The arm picks up the case and erects it in the same area where the loading takes place. Because the loading and case erection occur in the same area, it reduces the overall footprint and maximizes the speed of the P200.
Using Rexroth servos helped simplify the overall design for easy access and a smaller footprint. For the P200, Serpa opted for Rexroth’s IndraDrive intelligent digital servo drives, IndraDyn servo motors, and a linear Ball Rail
Instead of a mechanical drive, Serpa used Rexroth’s servo system to create an electronic line shaft with cam-profile movement. The P200 uses multiaxis synchronization with the ability to change motion profiles on the fly. Of the seven axes, four are synchronized using electronic cam shafts and three are point-to-point axes.
To achieve proper forming of the case, the erector and walking beam motion are tightly synchronized through SERCOS III communication with the Rexroth IndraDrives. The drives use cross-communication linking, with only one drive needing a field bus interface. The other drives use SERCOS to communicate to the PLC from the master drive.
Servo drives offer many features
The powerful and cost-effective IndraDrive servo drives offer many advanced features, including distributed intelligence, to close all the loops in each drive. The drives also provide 230 to 480 volt ac auto-ranging input voltage, absolute feedbacks to eliminate homing and a built in personality module or SD memory card for laptop-free replacement in minutes. The drives can store up to eight electronic cam profiles of 1,024 points each.
The IndraDrive servo drive’s internal virtual- master axis and precise synchronization allow smooth motion, even while the machine is running at high speeds. This reduces the loads placed on the mechanical parts of the machine, which, in turn, provides a high level of reliability. All motion and programmable limit switch outputs are based on a virtual master axis.
Serpa also used Rexroth IndraDyn synchronous motors, which offer scalability and compact construction with increased torque density, absolute encoders and high-resolution resolvers.
Control saves time and money
Rich James, Serpa’s director of marketing, said Bosch Rexroth components helped them develop a precise machine that offers scalability, straightforward programming, easy startup and the versatility to operate using an internal controller or in combination with any external PLC .
“Other servos did not solve our automation needs as efficiently or as cost-effectively as Bosch Rexroth,” explains James. “Bosch Rexroth has supplied a solution for our machines that is not only easy to program and start up, but saves time and money.”
By opting for a Rexroth drive and control system over other controls suppliers, James said Serpa reduced its installation and startup times by 30 to 35 percent. Serpa also was able to use 25 percent fewer parts on the P200 compared to their previous model, because it now uses fewer drive components and cables.
“Besides reducing the part count, another advantage Rexroth provided was helping with rapid changeover,” says James. “We can do a rapid, no-tools changeover in five minutes or less. Overall, with Bosch Rexroth, our hardware costs per machine are almost 40 percent less than with other brands we’ve used at Serpa. “We’re very happy with the final machine and the benefits of the control and linear-motion system.”
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