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Starting situation
Forming tools need machining not only for design modifications and repairs. This time, the goal was waste reduction. Shortening the size of the initial blank by a few millimeters has already significant ecological and economic advantages for a car sheet metal part produced in series. The use of an optimized sheet metal blank required milling on the forming tool, which weighs around 23 t. Picum was ideal for this task. The smaller blank required the adjustment of four guide elements (coarse guides) in the first forming stage OP20 of the tool for its safe positioning. The adjustment range of the guiding elements was already fully used beforehand and was no longer sufficient. Furthermore, two so-called fine guides had to be reinserted in the last tooling stage OP60 to ensure exact positioning of the sheet on the tool.
Procedure
To extend the adjustment range of the coarse guides in OP20, the four mounting shapes in the 13.5t bottom part were each extended by 5 mm towards the forming stage. The coarse guides dip into the upper half of the forming tool during press operation, because of their length. The corresponding clearances had to be extended by 5 mm each as well to prevent collision. The positioning of two fine guides in OP60 had several requirements regarding the machining. Pockets had to be milled that provide a large enough seating surface as well as a lateral stop to prevent rotation. Furthermore, it had to be ensured that the milled bottom surfaces were normal to the lifting direction of the tool. In addition, an M8 core hole was circularly milled and then threaded to fasten the fine guides. As in OP20, clearances at the corresponding positions of the upper half of the tool were also necessary in OP60 to avoid collision with the fine guides.
Advantages
The 12 milling segments could be changed time- and cost-efficiently as well as CO2-reduced due to the on-site machining with our mobile system and the omission of the transport of the 23t heavy forming tool to an external toolmaker. We realized time savings up to 71% and cost savings up to 45% with the new on-site machining process compared to a conventional modification process. In the described application, a transport-related CO2 quantity of 1850kg could be saved. This corresponds approximately to the average annual CO2 emissions of a medium-sized car with a kilometer reading of 15,000km. Another big advantage is that the planned deadlines for the next use of the tool could be met and the material savings due to the reduced blank size were immediately realized in production. This also saves money and valuable resources.
