Mechanism synthesis for the needle motion of an unconventional pile fabric machine

An unconventional pile fabric process has been invented and developed in the Mechanical Engineering Department of Loughborough University of Technology. The process uses two opposing rows of sewing-type needles and loopers to insert pile loops into a pre-formed base fabric. The needles describe a planar orbit, and in an industrial application of the novel technique, a cam mechanism is used to generate this orbit. The aim of this research is to synthesise a linkage mechanism to replace the cam mechanism for needle actuation. The inclination of the needle to the fabric is required to be controlled during much of the orbit. In addition, there is a limited area in which the mechanism may be located. In order to satisfy both these conditions without limiting the choice of possible orbit shapes, it was decided to generate the motion by means of a six-bar parallel-motion mechanism. The dimensions of the six-bar linkage are derived from the dimensions of a four-bar linkage which generates a suitable orbit. [Continues.]