Pushers guide to the right destination
"We rely on the pushers to work," states Michael Feneis, Technical Manager Depot 167 DPD Worms. "That's why we rely on SEW-Eurodrive." Drive and control technology from the Bruchsal-based automation specialist was installed in the system from the very beginning, when it was put into operation in 1994. The drives of the pushers (deflectors), which guide the parcels from the steel conveyor belt in the right direction to the exit transfer bridge, were getting on in years and needed to be replaced. As part of a retrofit project, the drive and control technology along sorter line B was completely replaced in 2019: 28 pushers, whose materials and mechanics remained the same as before, were given new drives.

In addition to the synchronous motors, SEW-Eurodrive installed six control cabinets, each with a controller, a supply module and up to five axis modules. Each individual axis module controls the synchronous motor of a pusher and ensures that the packages are given a proper push at the right time and in the right place. This directs them onto the correct conveyor route to the swap body and thus to the right destination.

Conversion in a short time
The retrofit project was designed for a weekend. On Friday, after the end of the shift in the DPD hall, Gabriel Currle, Service Electronics SEW-Eurodrive and project manager of the Worms project, arrived with his team for the first preparatory work on sorter line B. Two electricians and two fitters from the mechanical service team spent Saturday dismantling the existing control cabinets, installing the new control cabinets, dismantling the old drives, installing the new drives and laying all the cables.

The configuration of the drive functions, data backup, tests and commissioning were carried out by two service engineers from the electronics service. Everything was done by the evening. "I would never have thought that it could all be done in one day," says an impressed Michael Feneis. The technical manager expressly praises the smooth running of the conversion and the SEW service: "You can really rely on them!"

Precise movement
Some of the Sorterline A pushers are equipped with technology that is over 25 years old. "It still does what it's supposed to," confirms the Head of Technology, emphasizing that this speaks for the reliability and quality of SEW products. Everything else runs smoothly at the Worms distribution center too: the parcel data is recorded at the entrance gates in the unloading station at two central scanning stations: Dimensions, volume, weight. From now on, all parcel data, including the destination address, is stored in the computer. From the scanning station, the parcels are transported to the two steel belt sorters A and B and pass through the reading station, where the destination address is detected on the label. A rotary encoder is then used to control the pusher that moves the parcel to the correct changeover bridge - over the entire surface and with pinpoint accuracy, so that the parcel makes the sudden change of direction cleanly. "The challenge is to ensure that the pusher hits exactly the right point given the variety of different parcels. Both damage and jams must be avoided at all costs," explains Michael Meitzler. Light barriers would detect a jam and stop the belt.

Equipped for the future
Parcel distribution currently works perfectly without image processing and other sensors. However, it could be upgraded: if, for example, force and position control of the pusher deflection were to be implemented at the rejection stations in order to handle the parcels individually and gently, this would already be possible today with Movi-C components: "We are prepared for this. The automation system that has now been installed could implement a control system with new sensors immediately," confirms Gabriel Currle. Michael Feneis also believes that the system is equipped for the future: "If a module fails, we can simply replace it via plug and play, without having to set new parameters. This is because the Movi-C controller takes over the complete data management of the axis system in the system. In terms of maintenance, we only have to change the filters on the control cabinet's air conditioning unit from time to time. Apart from that, we only have minimal maintenance work," confirms Feneis. Everyone involved - the technical manager, the handling manager and the service provider SEW-Eurodrive - is pleased with the interaction and the smooth operation. At 9 p.m., the central depot in Worms is actually quiet - until the next morning when the parcels arrive. Then the parcels will arrive here that have been sent on the road overnight from another DPD distribution center by long-distance transport and are now being delivered to the end customer by delivery vehicle.

(published in materialfluss 10/20)