Monitoring feed magazines for carton blanks

One of the beer market’s most successful container sizes is the six pack, whether it comes in the form of the classic six rings and cardboard sleeve with a top clip or as a tray with a carrying handle. To enable systems such as wraparound machines to create these multipacks, blanks magazines provide a supply of flat carton blanks, which are extracted from their stack by a rotating collector or a vacuum gripper element, eg, before being singulated and set up in the machine.

Protecting the blank infeed against the risk of accidents

From a safety perspective, maintaining a sufficient quantity of carton blanks in the magazine provides a physical guard, as this blocks the opening between the blanks magazine and the actual packaging process, thus preventing the operator from having to reach directly into the moving mechanical parts of the machine. If the blanks magazine becomes empty, however, this area of the machine finds itself without protection and becomes accessible. Reaching into the parts of a machine while they are moving and therefore dangerous — during a material change or troubleshooting, for instance — poses a serious risk of injury. This must be prevented using appropriate safety-related measures. This is especially important given that standard EN 415-7, ‘Safety of packaging machines’, requires protection for the kinds of openings in physical guards that are created by factors such as empty blanks magazines.

Safety without ergonomics or flexibility reduces productivity

To date, many applications have provided a protective function in the form of mechanical tunnels that are used to maintain the required minimum distance from the hazardous point. An alternative design involves positioning the magazine at a height that in some cases can only be reached using climbing aids. However, not only do both strategies offer little in the way of ergonomics, they also complicate the routine process of filling the magazine and make it extremely time-consuming. What’s more, they require significant additional work on the mechanical elements, need a large amount of space and offer little or no flexibility when changing carton formats.

Safe magazine monitoring

In recent years, intelligent sensor and control solutions have made it possible to achieve both productivity and safety. SICK’s Safeguard Detector is a TÜV-certified safety system for detecting residual stacks of carton blanks in feed magazines used in machinery such as carton erectors, tray packers or wraparound packers. It ensures that there is always a sufficient quantity of blanks available in the magazine, eliminating the need for operators to intervene in the machine’s extraction and set-up mechanisms.

The system solution consists of two MultiPulse photoelectric proximity sensors plus a modular Flexi Soft safety controller. As a certified system, Safeguard Detector meets criteria up to SILCL2 in accordance with EN 62061 as well as PL d in accordance with EN ISO 13849.

The MultiPulse sensors identify carton blanks in the blanks magazine and are able to detect both very light and very dark colors and surfaces on the blanks. The two sensors are connected to a modular Flexi Soft safety controller, which evaluates the MultiPulse sensor signals using certified function blocks. As soon as the photoelectric proximity sensors detect that the residual stack quantity is at a critical level, the Flexi Soft outputs are switched off and the machine stops safely. It then cannot be restarted until the blanks magazine has been refilled to a sufficient level.

Productivity and safety

Whether it is part of a new set of machinery or being retrofitted, the Safeguard Detector has sensor and control technology that is easy to integrate. The system ensures reliable monitoring of the required minimum quantity available in the blanks magazine, thus ensuring optimum availability and productivity of carton erectors and wraparound packers.

Due to the small sensor housing, the proximity sensors require very little installation space. In contrast to tunnel systems, it is possible to keep the distances to the hazardous point short, which in turn ensures a small machine footprint.

When a format change takes place, there is no need for any alterations in the layout of the safety-related equipment, as the side guides of the carton magazine consistently maintain the same distance from the contour of the format blanks. This monitoring method makes carton magazines easier to access and more user-friendly.

Prepared to handle overarching safety functions

The Flexi Soft safety controller can be custom-programmed with the configuration software, which allows the system to be operated in a network with other safety applications. Sensor cascades can be connected as part of a control solution, providing an efficient way to monitor aspects of packaging plants such as doors, protective flaps and covers, with minimum wiring. Optional fieldbus gateways offer numerous integration and diagnostics options.