16 February 2010
The Pure-Pak PR90 machine (Figure 1) with a capacity of 9,000 cartons per hour can be used for filling milk, fruit juice, wine, soup or sauce into 1.5 litre rectangular cartons.
Non-contact safety sensorsEden E is a non-contact safety sensor designed for use in harsh environments (Figure 2). It consists of two complementary parts, called Adam E and Eva E, which are 12mm thick, 30mm wide and 60mm long.
The detecting distance is 12±2 mm which makes it easy to install them on a door, gate or hatch.
Eden has dynamic input and output signals. In contrast with mechanical or magnetic switches, Eden is active all the time, and a door requires only one sensor pair to achieve the highest safety level category 4.
Eden’s signal is monitored by a Vital safety module which can control up to 30 interlocked doors at safety category 4 according to EN 954-1. Vital can also monitor other safety devices at the same time.
Filling the cartonsThe Pure-Pak cartons are delivered to the dairy in the shape of blanks. The machine automatically forms the blanks into cartons and the cartons are then bottom sealed.
A few stations later, the cartons are filled by a servo-driven filler and lifter. The last station takes care of the top sealing of the cartons.
Depending on the type of filling machine, up to 27 Eden safety sensors are used. The E-version for harsh environment is ideally suited for high-pressure wash-down with cleaning and disinfecting foam (Figure 3). The automatic cleaning is carried out up to four times a day.
Another advantage of the electronic solution over the mechanical one is that no keys are needed, which means no mechanical deterioration. Recent tests have proven that Eden E can operate in a temperature range from -70 to +90°C.
Additional safety
Each machine is equipped with two Vital electronic safety modules (Figure 4) for reaching category 4 hatches supervision.
Vital dynamically supervises the Eden E non-contact safety devices. It has automatic or manual supervised reset, dual NO safety outputs, and an information output for reset indication and status information for programmable controllers (PLCs).
Up to 30 safety devices can be connected to each Vital. The result of the hatches supervision can be seen on a touch screen (Figure 4), where an open hatch appears as a red area.
The central emergency stop cabinet contains five safety relays with dual and monitored internal safety functions.
Lars Bengtsson, Project Engineer at Elopak, says he still remembers the time before Eden when the machine operation was interrupted at least once a week due to the failure of one of the mechanical switches. The downtimes had caused tremendous costs over months and years.
(This article adapted from a report by Anders Dieterle, Jokab Safety, and Lars Bengtsson, Elopak.)
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