Schuler Automation supplied a complete automated blanking line to Shanghai Volkswagen that can process either aluminum or steel coils.

Schuler Automation has developed a new, automated blanking line that allows Shanghai Volkswagen in China to process both aluminum and steel coils on the same line. The installation marks the first time Schuler has supplied a complete blanking line to Shanghai Volkswagen. In addition to a mechanical 630-t (695-ton) press, the line consists of various automated components including a washing unit, straightener, a coil-loading device, coil feed, cropping shears, and blank unloading.

Preliminary trials took place in April at the Schuler plant in Hessdorf, Germany. The system was then put into operation in China under the guidance of Schuler Automation's project management and start-up teams. The blanking line can process coil widths from 400 to 2000 mm (16 to 79 in) with thicknesses of 0.5 to 2.8 mm (0.02 to 0.11 in), and maximum coil weights of 30 t (33 ton).

Schular's line has an overall length of 55 m (180 ft). It is 17 m (55 ft) wide, and 8.3 m (27 ft) high. The system's coil-loading device features two assembly positions where coils are prepared for changeovers, and narrow-band coils on its front truck are supported by safety bars. The stacker at the end of the line has numerous switchboxes, and the system's top-mounted wiring assembly contains the blanking line's electrical and hydraulic cables.

The line has a blank washer that can be raised above the line by a lifting table when not needed, (e.g., when processing aluminum). Other features include a fully automated cassette changeover system for the straightener, as well as a stacking system design that accommodates additional vacuum belts to transport and release aluminum blanks.

The system's fully automated coil loading and thread-up from over or under includes clean and dirty rolls for processing the outer wraps. This prevents dirt from being transferred from the start of the coil to the rest of the steel coil by the rollers. A cropping shear separates the dirty or damaged leading edge of the coil. Dirt is removed from the coil material in the strip-washing unit, where a predefined quantity of oil is added. This increases the edge life of the cutting tool, since dirt transfers from the coil to the tool. When using aluminum, the washing unit is not needed, and the aluminum sheet is transported via a roller table located below the washing unit and fed to the straightener.

The straightener, with its topochrome-coated straightening rollers, uses the "12+1" system developed by Schuler. An optional, adjustable 13th bending roller gives the blanks a slight concave or convex tendency, contributing to manufacturing safety and simplifying movement of the blanks in the blanking press die.

In addition to the feed's two topochrome-coated rollers, there is optical as well as inductive weld recognition. With a length of 100 to 4000 mm (4 to 158 in), the feed works with an accuracy of ± 0.1 mm (0.004 in). The stroking rate of the blanking press is between 60 strokes per min for 100 mm (4 in) and 21 strokes per min for 4000 mm (158 in). The move-in oscillating shear produces rectangles, parallelograms, and trapezoids at a cutting angle of ± 30°.

The cut blanks are transported from the press/shear via telescopic conveyors, which are adjustable for length and width. Steel blanks are transferred to hanging transport by magnets. Vacuum cup conveyor belts are fitted to the stacker for aluminum. The blanks are finally stacked on pallets in two stacking positions, and the positioning system's rear stops can be arranged as individually programmed to ensure precise stacking.

Another technical highlight is the visualization program developed by Schuler Automation on the basis of WinCC (Siemens' visualization product running under Windows NT). This user-friendly program uses graphics along with pictures to monitor requirements when changing tools for new parts. The program operates faster through an interface to a Siemens S7 control module.

Jean L. Broge

AEI October 2000