Access guarding on pallet magazines –
with automatic restart
The increasing automation of machinery and systems places growing demands on the necessary safety concepts. Classic concepts, such as muting, are often pushed to their limits here. Our innovative safety solutions guarantee gapless safety, efficient material flow and high availability of your system, even with automated processes.
Pallet magazines are generally loaded using manually operated corridor supply vehicles – such as forklift trucks. Access guarding at the pallet magazine must ensure material transfer that is safe for the operator. Simultaneously should reduce interruptions of the work process to a minimum. This challenge was also taken up by the standardization body of EN 415-4 (Safety of packaging machines - Part 4: Palletizers and depalletizers). The current draft of the standard describes a defi ned series of signals for initiating an automatic restart for this purpose. The safety concept of our safety solution based on the revised standard ensures optimum utilization of the pallet magazine and requires no manual operator interventions.
Requirement:
Access guarding of the pallet magazine should prevent the entry of persons and simultaneously permit the entry of pallets by a forklift truck. After the forklift truck has again left the transfer area, restart should occur automatically to minimize the interruption of the work process.
Solution:
The access area is safeguarded by a safety light curtain. In addition, induction loops are embedded in the fl oor in the areas in front of and behind the safety sensor. The safety system can thereby distinguish between forklift truck and persons.
Operating principle:
Upon triggering of the safety light curtain, the work process of the pallet magazine is interrupted – regardless of whether a person or a forklift truck interrupted the protective field. If, however, the presence of a forklift truck is detected by the induction loops installed in the floor and if this then correctly executes the specified process sequence, the safety system initiates the automatic restart of the work process.
Advantages for you
- Optimum system utilization through automatic restart of the machine without manual operator interventions
- High reliability and availability
- Low service costs
- Optimum protection against manipulation
- Simple integration in the safety circuit of the primary control
System components and safety parameters
| Safety sensor: MLC 500 safety light curtain, with device columns for floor mounting | |
| Induction-loop set with evaluation unit | |
| System control: MSI 400 safety control | |
| Leuze safety program | |
| PL d in accordance with ISO 13849-1, SILCL 2 in accordance with IEC 62061 | |
| 2-channel safety output |