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Simulation der Schutzwirkung textilbasierter Splitterschutzvorhänge

Woodworking machine centers designed to cut wooden boards, solid wood, chip board, plywood and also these materials where these are covered with plastic laminate or edgings at highest flexibility and lowest costs are often equipped by partially encapsulated working tools. This results in hazardous risks to the operators in case of failure milling cutters by flying fragments at high speed up to 60 m/s. Therefore impact curtains of PVC-stripes to retain ejected parts of tools out of the working zone and minimize the risks were used. This curtain was tested by a test standard which reproduces the hazard of the ejection of tools parts. The testing equipment comprises a propulsion device, a standard projectile of 20 g, a support for the test object and a system that allows measuring or recording the impact speed of 70 m/s. The tendency to increase production velocity leads to higher rotational speeds of milling cutters. Now tightened test standards [1] specify 100 g projectile instead of 20 g at same test speed, with the result, that former PVC-curtains cannot achieve the retention effect without being too stiff for the application. The PCV stripes damage the sensible work pieces at their edges excessive. Because of this a new solution for encapsulating the working zone was developed using textile fabrics. Textiles do possess high strength and flexibility at same time. In a joint project of the Institute of Machine Tools, University of Stuttgart and the ITV Denkendorf [2], various textile materials and constructions of textile impact curtains were investigated and several textile solutions which fulfill the new test standard treating the work piece gently were developed. However a clear correlation between textile properties and the shooting results could not be found by comparison of experiment and test results, because textile fabrics are complex systems, where changing one parameter influence several others [9-12]. As the retention mechanism and also the textile parameters influencing the protective effect were not known, FE-simulation models of textile impact curtains were developed and ballistic impact according to the new test standard were successfully simulated by ITV, which is the subject matter of this paper.

application/pdf J-I-03.pdf — 5.3 MB