Bando Chemical Industries, Inc.

Michio Tanaka

Hiroshi Matsuoka

Susumu Onoe

Tsutomu Shioyama

Akinori Fujiwara

Osamu Sakamoto

Masayuki Kitabayashi

One end of a flexible positioning cord is fixed on one end side of a molding drum and the positioning cord is then pulled from the other end side thereby applying a tension to the positioning cord. The tensed positioning cord presses a joint of an extensible fabric into one of tooth part forming grooves to position it therein. Next, a tension member cord is wound in a spiral form and the tension applied to the positioning cord is then relieved to allow the removal of the positioning cord from the tooth part forming groove. Thereafter, an unvulcanized rubber sheet is wrapped around the extensible fabric wound with the tension member cord, and the resultant substance is then subjected to cure through the application of pressure thereby forming a cylindrical slab. The slab is cut into round pieces at specific widths thereby obtaining synchronous belts. In this manner, there is obtained the synchronous belt in which the joint of the extensible fabric is positioned in the tooth part forming groove of the molding drum so as to avoid movement and is correctly located on a tooth tip end of a tooth part.

Fabric positioning apparatus used in producing synchronous belt

A woven fabric for covering a tooth part formed on a belt body of a synchronous belt is woven with a lengthwise yarn and a widthwise yarn. The lengthwise yarn is made of a crimped yarn of synthetic fiber or a covering yarn in which a crimped yarn of synthetic fiber is wound around an elastic cord yarn. The widthwise yarn is made of a spun yarn of synthetic fiber or meta-linked type aromatic polyamide fiber. The widthwise yarn expose more to the woven fabric surface than the lengthwise yarn. Thus, the belt life is lengthened and the noise reduced.

Synchronous belt

In a toothed belt, each tooth of the belt in longitudinal cross-section has a tooth top part composed of a pair of tooth top portions and a tooth tip portions formed in circular arcs, respectively, whose radius dimensions and location of centers are predetermined by a set of equations and inequalities so that a first contact point of the belt tooth with a pulley groove approaches to a tooth center line. In a power transmission device using the abovedescribed toothed belt and a toothed pulley, a shape of each pulley groove of the pulley is predetermined by a set of equations and inequalities so that a compressive force applied to the belt tooth during engagement concentrates to the tooth center line.

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Kobe, Japan

Michio Tanaka