SIGNAL ANALYSIS OF DYNAMIC FORCES EXPERIENCED BY INDIVIDUAL NEEDLES IN HIGH-SPEED NEEDLE PUNCHING

Dynamic forces experienced by individual needles are measured and inve stigated in time and frequency domains to deduce the needle force sign al due to fiberweb resistance during penetration and withdrawal of the needles from the fiberweb. A technique developed to deduce a needle f orce signal due to fiberweb resistance for the entire needling cycle f or any number of cycles enables the determination of peak penetration force, peak stripping force, and penetration and stripping energies du e to fiberweb resistance. The force parameters are essential to loom a nd needle manufacturers for design purposes. Equally important, the fo rce parameters are related to needled fabric end use performance. This relationship can be used to produce consistent fabric properties by c ontrolling the process variables that influence needle force parameter s.