Production technologies for double-walled-sheets

We have a world wide unique know how to produce double-walled-sheets.

1. Improvements of the conventional process

1.1 Double wall sheet dies with MEMBRANES and SUPERFLEX LIPS for a more precise fine tuning of the local melt streams and thus of the thickness distribution across the width of the outer walls of the sheets. These dies give rise to a die controlling with the help of small geared adjusting motors and the measurement of the wall thicknessí with the help of our wall thickness measurement system (see 1.2). Wall thickness tolerances less than 5 % are reachable!

1.2 Wall thickness measurement for the upper and lower wall of the sheet. The mechanical behaviour of a sheet is that of itís thinnest part. By avoiding thin parts in the sheet you save a lot of money. The only problem is that with conventional equipment it takes you a long time to adjust the die. This is because you have always to wait a long time after an adjustment until you are able to cross cut and to measure the thickness distribution of the sheet walls. Positioning the thickness measurement directly behind the calibrator gives you a very quick and precise (accuracy 0.01 mm) information on the thickness distribution. This shortens the start up times for the lines extremely. In combination with our new membrane type die with superflexible lips you can produce closer tolerances and thus run your process more economic.

2. Our process to produce a new quality of double walled sheets

2.1 Process to produce conventional double walled sheets with absolute flat surfaces (no depressions on top of the ribs) and improved surfaces qualities (no scratches resulting from the calibrator).

We are speaking of a totally new way to produce double walled sheets. According to our knowledge it should be possible to reach a world wide patent for this technology. This new process which we have partly tested on a pilot line results in an new quality of double walled sheets. Such sheets are up to now not available on the market. The conventional light-weighted double skin sheet is not at all suitable for all applications where an absolute flat surface is afforded. The new process avoids the depressions in the surfaces on top of the rips which are characteristic for all conventional double walled sheets. Additional the resulting sheets have no longer any scratches resulting from the calibrator. At least it can be forecast that compared to the conventional process the new process should be more economic, as higher production speeds should be reachable.

2.2 Process to produce double walled sheets with waved rips to improve the sheets general stiffness and especially its stiffness perpendicular to the rips.

We have performed first trials to establish a technology to produce extreme stiff and light weighted double skin sheets again with absolute flat surfaces. In direction of the extrusion the rips have a sinusoidal waved geometry which gives the sheet a much higher stiffness compared to conventional sheets with straight rips. Waved rips are much less sensitive to bending. These sheets are a little bit comparable to honeycomb sandwich sheets with the advantage that they are produced in a very economic continuous extrusion process. We are looking for companies who are interested to establish such an extrusion line.