The press manufacturer Schuler is working on new technologies to cut energy consumption in half at an automobile stamping plant. Achieving similar potential savings in overall car-body manufacturing has turned out to be more difficult.

 

The new, five-stage servo press line at the Leipzig BMW stamping plant transforms sheet steel into pressed parts that are later assembled into the shell of the BMW 1 Series. The auto manufacturer is investing 70 million euros in plant equipment from Göppingen-based press manufacturer Schuler, which already built the first press line at the Leipzig plant four years ago. Equipment like this is not just about power, precision and speed, but increasingly comes down to using the lowest possible amount of energy.

Even the first press line was equipped with a pause mode. When the equipment is stopped for a longer period of time it turns off the unnecessary power guzzlers – the aggregates for hydraulics, lubrication and cooling. An additional energy-saving function is the regenerative braking of drive motors, allowing the braking energy of individual presses to be recovered. This happens when the press slides are decelerated. The energy obtained can be used to drive other presses.

Most of the electricity in a press line, however, is used by the hydraulic drawing cushion during the first stage of operation. The sheet metal to be reshaped is held by the drawing cushion with a precisely measured force, determining how much material flows into the mold. Schuler experts have meanwhile developed an energy-saving drawing cushion, which thanks to improved construction drastically reduces the electricity consumption of the drawing cushion, by 57 percent.

The BMW plant in Leipzig, whose second press line has already implemented the energy-saving drawing cushion, is expected to profit from this development too. What’s more, Schuler is already working on new technologies to enable further economies. The press manufacturer has estimated that overall energy savings in a car-body stamping plant with conventional equipment could reach 50 percent.

Fifty-percent savings – this was also the aim of the Innocat Innovation Alliance “Green Carbody Technologies” launched in 2010 with the participation of Schuler. This collaborative research project included 60 partners from the automobile industry, the steel and supplier industry, as well as the Fraunhofer-Gesellschaft, working together on solutions to make the production of vehicle bodies more environmentally friendly and resource-efficient than it has been to date.

The project, completed in 2012, only resulted in potential energy savings of 10 percent, however. One possible reason for this is that of the 60 subprojects originally planned only 30 were carried out with funding and published with the results. The results of the remaining projects, conducted by the industry without financial backing, are unknown.

A number of Innocat approaches can be found in a long-term Fraunhofer future project: energy- and resource-efficient production in a largely emission-neutral factory with the ergonomic integration of humans. Researchers hope this “E3 factory” will help overcome previous technological barriers, creating new production systems and forms of organization. This will require the optimization or even replacement of many manufacturing processes.


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