Case erectors made quickly, flexibly and safely thanks to safety automation technology
December 6, 2019
by DIRK SCHLÜTER, PILZ GMBH & CO. KG
Cardboard trays or secondary packaging must be geared precisely to the product and its logistical requirements.
As the means of presenting the goods they should also meet the handling and design concepts of the respective customers.
The Tablomat LE from Wächter folds and glues the widest variety of formats.
The configurable safe small controller PNOZmulti 2 and the safety gate system PSENslock from Pilz Gmbh & Co. KG are responsible for a flexible operating concept, rapid implementation of format changes and a smooth operation.
End-of-line packaging is no different from the rest of the packaging sector in demanding flexibility and efficiency: Rapid changes to new formats, including the ability to adjust sensors and actuators quickly and simply are essential issues relevant to Industry 4.0 and batch size 1.
Over the years, packaging machine manufacturers have swapped relay-based hardware for more reliable, more flexible software systems that are less prone to problems.
This went hand in hand with the optimisation of safety solutions, which essentially was also software-based.
In the process of redesigning an erector machine, Wächter Packautomatik, based in Bad Wünnenberg-Haaren, Germany is dedicated to the automation of packaging processes.
There was a clear need for action because the previous model of the Tablomat LE no longer met the increased demands for performance and efficiency.
“The mechanical safety switches that we used to use on the safety gates were prone to problems and sometimes produced implausible diagnostic messages,” says Jürgen Schulte, production manager at Wächter.
“Besides, there were now convincing alternatives to intricate and complex wiring. That’s just two of several reasons that prompted us to think seriously about sustainable automation and safety concepts.”
In addition to the plant design and installation requirements, this supplier of intelligent packaging solutions set high standards for plant availability, reliability, flexibility and diagnostics.
The requirement was for the diagnostic data from the sensors to be available to the machine controller (POC) in real-time via an EtherCAT or PROFINET Gateway.
The plant operator was to have a comprehensive overview of the machine status at all times.
“We worked with Pilz to develop a solution that would best satisfy both our own needs and those of our customers,” Schulte stresses. “It was an advantage that we were able test the potential Pilz products rigorously in advance.”
The new Tablomat LE is an automated tray and case erector, which is used to manufacture secondary packaging for a wide range of products.
The machine produces up to 30 ergonomic, elegant secondary packaging items per minute, depending on the requirement.
Hot glue is used to seal the packaging.
With format cartridges that can be exchanged quickly, simple spindle adjustment and large hinged and swing gates, format changes are quick and flexible to implement.
Centralized, electronic parameter and recipe management with a memory capacity of up to 25 different product recipes guarantees the shortest setup times.
An intuitive touchscreen panel ensures a simple, clear process for handling and monitoring as well as rectifying faults.
First a tray is drawn from the magazine into the slot via a vacuum suction system.
A servo motor driven slider moves the pre-punched carton towards the tray punch.
In an intermediate station the raw product is pre-folded; as it passes through, the glue is applied for final assembly.
Finally, the punch pushes the carton through the format shaft and erects the tray for the finished secondary packaging. The risk assessment produced by Wächter resulted in performance Level PLd in accordance with EN ISO 13849-1.
The configurable safe small controller PNOZmulti 2 from Pilz is tasked with safe monitoring of the four safety gates, the installed E-STOP pushbuttons and communication of customised diagnostic data to the PLC via fieldbus module.
The narrow, 45-mm base unit PNOZ m B0 provides 20 safe inputs and four safe semiconductor outputs and is modular, flexible and expandable where necessary.
It just takes a few clicks to select the hardware and create the safety circuit via drag and drop.
The graphics-based user interface conforms to the Windows standard; all the elements in a safety circuit are available as icons or in selection menus.
As a result, certified blocks for emergency stop or safety monitoring, for example, are flexible to select and can be linked to the outputs via logic operators.
Comprehensive diagnostic options with customised diagnostic texts reduce downtimes.
If a fault occurs, features such as plain text messages with precise information on the location, clearly defined responsibilities and integrated first fault display all ensure that production is quickly restarted.
As an open control system PNOZmulti 2 can also be used flexibly and industry-wide, independently of the higher-level operational or plant control system.
It communicates with every common fieldbus and, depending on the application, meets safety requirements up to PL e and SIL CL 3.
The fieldbus modules can be exchanged without having to change the program and enable PNOZmulti 2 to be connected to the various communication networks.
The safe small controller is certified worldwide and can be used internationally for safety and automation functions, irrespective of the machine and plant type or industry. Instead of the previous mechanical safety switches that were prone to problems, the four safety gates on the Tablomat LE are now fitted with the non-contact safety gate systems PSENslock from Pilz.
These combine safety gate monitoring with a non-contact magnetic interlock in just one unit.
This combination of safe position monitoring and process guarding makes PSENslock suitable for universal use and satisfies the highest safety requirements.
Signals from the E-STOP pushbuttons and safety gate systems PSENslock are evaluated through PNOZmulti 2, with the status reliably displayed on the operator panel as part of the diagnostic function.
“Together with Pilz we have achieved all the stated objectives on the Tablomat LE: the case erector is impressive with its clear, streamlined wiring and it can be reconfigured for new tasks in the shortest possible time,” Concludes Schulte.
“The plant is enjoying virtually trouble-free operation, the operator has a comprehensive overview of the current machine status at all times.”