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Monday, November 30, 2020

How precise is COPRA® RF DTM?

Technical Information

To answer this question, the software has been compared to theoretical and practical experiments (cold forming of steel sections with wire strain gauges) conducted at the Institute of Manufacturing and Forming Machines (PTU) of the Technical University of Darmstadt, Germany. The experiments were within a research project on behalf of the Studiengesellschaft für Stahlanwendung at Duesseldorf, Germany and was financially supported by data M and roll forming companies.

At this point it should be mentioned, that COPRA® RF, too, was developed on the basis of a project supported by above mentioned research association - the Studiengesellschaft at Duesseldorf. The project was completed in 1987. Since then, data M has been in touch with both the research association and scientific institutes involved in cold rollforming. In the meantime, the managing director Mr. Albert Sedlmaier has proposed and prepared further projects. Other members of data M Sheet Metal Solutions GmbH have been participating in project-related workgroups.

FEA-Simulation and Rollforming Experiment

In the frame of project P219 of the reasearch group for steel applications (Studiengesellschaft) a cold rollforming experiment was conducted at the Institute of Manufacturing and Forming Machines (PTU) of the Technical University of Darmstadt.
The special feature of the experiment was the sampling of material strains with the help of wire strain gauges. 

Description of the Experiment:

  • Profile: U75/100/75 x 4 mm
  • Forming: 30-degree steps, i.e. 0°, 30°, 60° and 90°
  • Machine: experimental machine of the study group at the Technical University of Darmstadt, Germany
  • Tool diameter: Bottom roll: 180 mm; Top roll 420 mm;
  • Tool diameter: Side rolls: approx. 180 mm
  • Distance of stands:  450 mm

Results of practical experiment:

Illustrated are changes in longitudinal strain (which, according to the latest technological developments are the reason of undesired deformations).

The chart shows the strain values of the material which are due to the forming curves imposed by the tools.

Results of the COPRA® RF DTM calculation:

The same parameters were specified. The formula according to Hauschild used an exponent of 1,3 which is equal to the value recommended for this shape and dimension.

Of special interest is the almost identical quality of the strain course. Even the numerical results are within the same range as the curves obtained by the DMS experiment.
It cannot be said with certainty, whether the values behave in the same way with complex profile geometries.
But our customer´s feedback has proved in many cases that COPRA® RF DTM is able to increase your products quality.
However, this much is certain: COPRA® RF DTM provides excellent results within a short calculation time (up to 5 seconds).

Designers therefore have a handy tool at hand that helps them identifying weak points and mistakes early.