Servomotors make Kirk-Rudy tabbing machines faster and more accurate

Oct. 6, 2011
By replacing stepper-motors with servo-drive systems, Kirk-Rudy was able to boost linear speed from 350 to 500 ft/min on its new tabbing machines.

Resources:
Kirk-Rudy Inc.
Red Lion Controls
Yaskawa America Inc.

When postal regulation changes mandated the placement of a third piece of tape on mass mailings, a manufacturer of paper-handling equipment had to economically meet the new requirements quickly. A switch from stepper motors to servodrives did the trick.

Postal paper handling has changed in the past 40 years. Machines today must accommodate sample packets, CDs, plastic cards, and other items not traditionally associated with mail.

A few years ago, the USPS updated its specifications for tabbing — how tape goes on mailers such as brochures, newsletters, flyers, and so forth. Previous rules placed two tabs at the top of the mailer. The new specifications call for tabs on the leading and trailing edge of the paper to avoid jams during handling. Mailers now needed three tabs instead of two. Adding that third tab on the trailing edge of the paper made the process more difficult.

Paper being fed with an open edge for inkjet printing of the address has to be turned 90° to add the back tab. This action must be done as the mailer travels in a straight line at up to 350 fpm.

The first and most-obvious solution was to simply add another tabbing machine. However, both big and small mailing services didn’t like the idea of buying a new machine or finding the space for a table to hold it. They wanted a single, compact system that could attach the new back tab without slowing the workflow.

Paper-handling equipment maker Kirk-Rudy in Atlanta came up with the KR545T Tabber, a machine that can apply multiple tabs or labels on three sides in a single pass. The tabber needs only one transport table. It then folds it underneath while the mailer continues to move.

Earlier machines with this design used stepper motors. But attaching three tabs in a more-complicated arrangement while keeping up speed necessitated the move to servomotors. Kirk-Rudy’s first servo-equipped machine handled speeds up to 350 fpm, but even faster operation, along with greater accuracy, became the redesign target.

Another design goal was to simplify the current control system of four individual PLCs with an HMI control panel. The original design needed extensive programming.

Servos for the new design came from Yaskawa America Inc., Waukegan, Ill. The Yaskawa team had to get the label dispensing to start and stop accurately at high speeds. With that goal met, the next phase aimed at implementing the new tab kicker.

Yaskawa Sigma-5 servomotors and amplifiers implement the feed and kicker tasks. The Sigma-5 amplifier accommodates high-resolution encoders, along with advanced tuning algorithms for responsive and stable performance. These factors helped boost the machine speed by more than 20% while keeping near-perfect accuracy. The new system places and seals a 1-in. tab in just 10 msec at linear speeds up to 500 fpm.

Tolerance of tab placement also improved from 1/16th of an inch to within 1/32nd of an inch or less. In tests where the same mailer passes through the tabber several times, the new tab so closely aligns with the old that the eye sees only one tab.

To further simplify the design, the four servomotor amplifiers now connect to a single Yaskawa MP2310iec networked controller. The single controller replaced the four individual PLCs in the old design.

The Yaskawa controller uses an IEC-61131-3 programming environment. Programming time is reduced by downloading prewritten software libraries from the Internet. Minor programming changes are now a simple task.

The Yaskawa controller includes a built-in Web server, accessible via any browser, that lets programmers update programs or firmware at a distance. Alternately, customers can receive updates through e-mail.

The new HMI control panel from Red Lion Controls, York, Pa., includes a unified alarm that eliminates the need to transmit alarm information directly from the controller. All alarms now display in one spot, allowing for quick identification of the warning or fault condition. Alarms may also be accessed via the Web interface, letting Kirk-Rudy remotely identify the source of the alarm or fault and resolve it quickly without the need of a field service call.

© 2011 Penton Media, Inc.

About the Author

Robert Repas

Robert serves as Associate Editor - 6 years of service. B.S. Electrical Engineering, Cleveland State University.

Work experience: 18 years teaching electronics, industrial controls, and instrumentation systems at the Nord Advanced Technologies Center, Lorain County Community College. 5 years designing control systems for industrial and agricultural equipment. Primary editor for electrical and motion control.

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