Abstract: A method and apparatus are provided for forming pleats in a thermoplastic material by feeding a continuous web of sheet-like thermoplastic material to a pleat forming apparatus and subsequently drawing the web through a bonding device. The pleat forming apparatus includes a rotating drum that has a plurality of apertures and a plurality of radially extensible teeth positioned in peripheral slots. The teeth are spring-biased inwardly to a retracted position within the drum but are extendable, under the urging of an internal cam, to a position wherein a portion of each tooth protrudes outwardly from the drum. The web is carried around the drum and the teeth protrude into the web forming pleats.

Abstract: A method and apparatus are provided for forming pleats in a thermoplastic material by feeding a continuous web of sheet-like thermoplastic material to a pleat forming apparatus and subsequently drawing the web through a bonding device. The pleat forming apparatus includes a rotating drum that has a plurality of apertures and a plurality of radially extensible teeth positioned in peripheral slots. The teeth are spring-biased inwardly to a retracted position within the drum but are extendable, under the urging of an internal cam, to a position wherein a portion of each tooth protrudes outwardly from the drum. The web is carried around the drum and the teeth protrude into the web forming pleats.