Keeping Control Systems in the Family
A packaging company’s sister division designs control systems for liquid fillers.
|Bosch Rexroth’s control systems provide smooth operation for Bosch Packaging’s liquid fillers.|
Jeff Jackson, product manager for Bosch Packaging (Minneapolis), didn’t have to look very far for a new control system for the company’s liquid-filler machines. In fact, all he had to do was consult his own company directory.
That’s where he found Bosch Rexroth (Hoffman Estates, IL), a components supplier to Bosch Packaging and other pharmaceutical and medical packaging machines. The sister division to Bosch Packaging recently provided a precise control system for its FLM 2000-, 4000-, and 6000-series liquid-filler machines. The machines can perform two-fill operations at rates of 300 vials/min. and single-fill operations up to 600 vials/min.
“It was really an optimal solution,” says Jackson. “They had the technology, the parts, and the support. And the fact that they are part of our company made it the easiest choice possible.”
Jackson explains that the system for loading liquid-filled pharmaceutical vials into trays was formerly a mechanically driven four-axis ma-chine. Bosch Rexroth redesigned it and incorporated servos and an integrated motion system. The result was reduced costs and maintenance and improved reliability, according to Jackson.
Precise Control System
Bosch Rexroth’s challenge was to provide an extremely precise control system to electronically synchronize 9–28 axes of motion. The system also had to delicately handle the transport, filling, and check weigh processes of the vials at high rates.
“It now runs at speeds of 400 per minute, 25% faster than the nonservo design,” he says. The reconfigured machine uses four MKD digital servomotors from Bosch Rexroth for all four axes of motion. An infeed of a row of trays is one axis, the vertical and horizontal motions of the vial pick-and-place device make up the second and third axes, and the indexing of the vial tray comprises the fourth.
The machine’s servo controls are used to precisely synchronize the infeed star wheel, transport system, nozzle motion, In Process Control (IPC) check weigh system, pumps, stopper, outfeed starwheels, outfeed scroll, and outfeed magazine. Empty vials are entered on one end of the machine, filled, checked, stoppered, and dispensed to a handling system at the other end of the machine. “It was a big step to get this all in place,” says Jackson. “But the system was designed so well that it really made the entire process very smooth.”
The servomotor that handles the vertical axis of the pick-and-place robot uses two Bosch Rexroth ball screws to give it the required gear ratio. However, the other three use Bosch Rexroth planetary gear boxes. “If you require slow motion, the motor can still run at a speed it’s comfortable with while the gearbox delivers the gear ratio required for the slower speed,” says Jackson.
The Bosch Rexroth machine fills groups of vials in a continuous fashion. The transport carrier is the machine’s master, to which all other servos are synchronized. The machine contains an IPC weigh scale that can precisely weigh the vials and adjust the fill level automatically on a continuous basis. The filler and IPC systems use the robotic capabilities of the control system, which has kinematic capabilities to provide exact motion profiles. “The kinematic technology is complex,” says Jackson. “But it provides the best method for this system.”
Intelligent Servo Drives
Jackson admits the project’s challenge was daunting at first. “It’s an incredibly complicated process,” he says. Bosch Rexroth, however, offered what he calls a “perfect” solution: multi-axis electronic line shafting (ELS) and camming capabilities. The powerful multi-axis controller, capable of up to 40 axes of servos, allows for demanding applications to be accomplished on a single controller. The Bosch Rexroth PPC controller handles complete machine control, including logic, motion, and I/O. The controller receives help from four Bosch Rexroth Ecodrive intelligent servo drives, one for each servomotor.
“You don’t have to give the PPC controller the task of telling the servomotors all the things they have to do,” says Jackson. “They get the information they need from their drives. It really frees up processing time because there aren’t as many algorithms and calculations to perform.”
In addition, Bosch Rexroth’s use of both ELS and robotics capabilities allowed for a single control to run the entire machine. Control-based PLS and multimaster functionality were also required to synchronize and track products through the machine. Jackson explains that the control operates the infeeds, transport, stoppering, and outfeed in a mode of operation involving ELS phase synchronization. The nozzle motion, IPC, and pumps operate in ELS control cams that are built on the fly based on recipe changes made through a Human Machine Interface (HMI).
Since the distributed intelligent drives handle all time-critical functions inside, those functions also occur much faster than if they were handled in the controller, according to Jackson.
One of the main benefits of the collaboration with Bosch Rexroth was the money saved, according to Jackson. He says the integrated PPC controller means the machine is less costly to build since there is no need for separate controllers. The use of a pendant-style HMI screen, supplied by Xycom Automation (Saline, MI), also saves costs. “The old model had an HMI screen, but it was placed wherever the customer wanted it,” says Jackson. “That meant custom engineering, extra time, and extra cost. With this pendant approach, we can build the same standard machine for everybody.”
The Xycom Pro-Face HMI screen is linked with the Bosch Rexroth PPC controller through serial data communication, says Jackson. In addition, a SERCOS communications protocol is used as a motion control network. SERCOS digital communications allow for on-the-fly programming changes based on dynamic changes on the machine.
Another benefit of the Bosch Rexroth system is the use of electronic line shafting. “Along with the PPC, the shafting allows for absolute motor feedback and the ability to run all axes off a single controller,” says Jackson. “It allows for machine recovery after a jam or power outage. This way, everything stays synchronized.”
Simplified Control Architecture
Bosch Rexroth also offered Bosch Packaging simplified control architecture. “It communicates openly with all major interfaces,” says Jackson. “The FLM utilizes the Ethernet TCP/IP and ControlNet interfaces on the machine, and the control monitors each of the vials through the machine. If there is a vial missing or a vial that was determined by the IPC check weigh to not be filled properly, that vial is not stoppered and will be discarded by the reject wheel.” All of those functions are done with the use of a programmable limit-switch output from the control.
Both drive-based and control-based PLS functions control pneumatic gates and vacuum functions for the infeed gates, stoppering, and product reject removal from the outfeed starwheel, Jackson notes. Any changes in the machine recipe or timing of the machine in different areas are sent as a variable change to the controller. The PPC controller then makes changes to each of the axes. “This allows for synchronizing and unsynchronizing of various sections of the machine during normal operation,” says Jackson.
Jackson reports that Bosch Packaging is working with Bosch Rexroth on further projects. “There’s another one going on right now,” he says. It’s also likely the two divisions will work together in the future. “Their system works very openly,” says Jackson. “It was perfect for us and easy to implement and use.”
Bosch Packaging is also working with two major pharmaceutical companies, according to Jackson. Those projects involve companies changing over from a batch processing system to the Bosch Rexroth continuous-line system.
Jackson says that Bosch Rexroth also fit the bill of a supplier who offered a powerful solution that was well supported in North America, Europe, and Asia. “The support we got from them was excellent. Bosch Packaging really needed a strong worldwide support network for this project, and Bosch Rexroth provides that,” he adds. “Using a Bosch Rexroth solution was just a smart choice, especially since they’re a sister company.”