Storage & Handling: Robotics Move Palletizing into High Gear

When it comes to in-line palletizing and depalletizing, many smaller packagers steer clear of automating, because it can be expensive, especially the more complex robotic equipment that requires on-staff specialists. But that’s precisely the niche market Automated Motion (AMI) is successfully developing, with its GP Series gantry-style robot. Incorporating a motion-and-logic control package, the system is affordable yet designed to help smaller packaging operations automate the pallet-building process. Or it can assist larger users that may run several stockkeeping units at slower rates or want to reduce robot training costs.

The servo gantry palletizers utilize a combination of Bosch Rexroth’s PPC-R motion control, a programmable logic control package and VisualMotion 10 software to simplify and facilitate pallet-building control and programming. As a result, the systems require less training by operators and maintenance staff to run, maintain and troubleshoot effectively. And it puts automated palletizing within reach for many of AMI’s customers who want to replace hand palletizing.

AMI designs and builds robot systems in both a gantry style and with six-axis, articulated-arm manipulation. The GP Series can be operated by manufacturers without the need for specialized robotic programmers. Explains sales manager Jeff Ayotte, “The advantage of using gantries is that they require a lower level of operator training than what’s needed to run a full six-axis robot.”

Incorporating the PPC-R controller (the R stands for rack-mounted), AMI’s gantry palletizers efficiently palletize, depalletize and handle cases, cans, bags, boxes or other packages with a minimum of setup time. The gantry’s five axes of motion include left and right motion, forward and backward motion, up and down motion, 360-degree rotation and 90-degree tilt capability.

“Typically, a gantry can handle heavier payloads than an articulated arm,” Ayotte explains. “Both styles can usually perform twelve picks a minute, if not more. Running a larger number of stockkeeping units at slower volumes—say one to two cases per minute—the advantage of a gantry is that it can cover more pallet positions with one system. It’s not a matter of one technology being superior; it’s a matter of the requirements of the application. With robotics, you can palletize as many as the reach allows. A gantry can be designed to span a much larger area, and thus cover more [production] lines and pallet stations than can an articulated arm. The limit really depends on what the customer wants.” Ayotte goes on to say that the standard model of GP Series robotic palletizer gantries may represent only two-thirds of the cost of other robots, mainly because of the simple operation. “With dropdown recipe menus, a touchscreen operator interface and error diagnostic screens, the front-end control really makes it easier for the operator to learn. “Larger companies also like the Bosch Rexroth PPC controller, he says, because it provides open communication, allowing information-sharing using industry-standard protocols. “This saves time and improves performance across the entire line,” adds Ayotte. The PPC-R’s teach function employs icon-based programming with standard ladder logic, which makes it easy to use in end-of-line applications, according to AMI. Its middle-of-the-road approach bridges the gap between operations that want to replace hand palletizing but can’t or don’t need to make the full leap to articulatedarm robotics. Says Ayotte, “It can also serve larger operations that want a cost-effective, work-horse machine for palletizing as many as twelve different products in one system.” At the heart of the control package is the PPC-R, a compact controller from Bosch Rexroth’s Electric Drives and Controls technology group. Its platform works as a PLC and as a motion controller, depending on the application and software. It can solve complex automation tasks by grouping multiple PPC controls and masters and can manage up to two cascading masters and a maximum of 40 slave axes in a SERCOS ring. According to Bosch Rexroth sales engineer Peter Caldwell, who helped Ayotte design the control system for AMI, users may connect up to 32 PPCs to each other using a cross-communication interface, which allows the assignment of the master positions to the slave axes in various SERCOS rings. “AMI hasn’t used this feature yet, but the idea is that one of its palletizers can be married to someone else’s cartoner that uses a PPC, and the two machines can share position data to synchronize the positions,” says Caldwell. The number of synchronized drives is almost unlimited, and it becomes possible to separate the machines into independent sections. “We selected the PPC-R because it represents the latest generation of technology for combining motion control and PLC logic into one package,” notes Ayotte. “An operator can run the entire machine with one package of software, and we don’t need a separate PLC and motion controller.” Complementing the PPC is Bosch Rexroth’s EcoDrive Cs, a compact servo drive in the low power range from 100 to 750 W. The compact drive works on single-phase and three-phase supply systems with input voltages up to 230 V. Among the most compact servo drives available, most units are just 55 mm wide, 182 mm high and 170 mm deep. The EcoDrive Cs provides industry-standard interfaces, including SERCOS, DeviceNet, CANopen or PROFIBUS-DP. It is suitable for use in systems with interconnected, multi-axis configurations, or as intelligent single-axis drives on a standardized fieldbus. Bosch Rexroth says the EcoDrive Cs firmware embodies process-oriented technologies, including electronic gearing, cam tables and fast registration inputs, making it a suitable choice for packagehandling systems. User programming is simplified with intuitive, Windows-based commissioning software called DriveTop. The 16 Mbit/sec SERCOS interface also can be used with Bosch Rexroth’s motion control solutions like the PPC-R, as well as third-party control systems.