Abstract: A split tire mold having a tread ring in which provision is made for venting air circumferentially across the inner surface of the tread ring so that the air escapes from the parting line of the mold halves, dispenses with widely used, conventional, radially protruding vent stubs. The air is vented through "butterfly-shaped" or "double-wedge-shaped" arch-vents which provide passage for trapped air above each tread block of the tread as it is moved against the inner surface of the tread ring. The shape of the arch-vent passages and the angulation of the wedges is critical to the effectiveness of the arch-vent which forms an arch-vent bridge of cured rubber in a cured tire. The configuration of the bridge allows as cured tire to be easily removed from the mold cavity without leaving a broken-off piece of the rubber bridge to plug the arch-vents. This arch-vent design leaves unobtrusive flat-sided, narrow wedge-shaped pieces of rubber as the arch-vent stubs, tapered in two directions.

Abstract: A split tire mold having a tread ring having arch-vents for venting air circumferentially across the inner surface of the tread ring so that air escapes from the parting line of the mold halves. The "dougle-wedge-shaped" arch-vents provide passage for trapped air above each tread block of the tread as it is moved against the inner surface of the tread ring. The shape of the arch-vent passages and the angulation of the wedges is critical to the effectiveness of the arch-vent which forms an arch-vent bridge of cured rubber in a cured tire. The configuration of the bridge allows a cured tire to be easily removed from the mold cavity without leaving a broken-off piece of the rubber bridge to plug the arch-vents. This arch-vent design leaves flat-sided, narrow wedge-shaped pieces of rubber as the arch-vent stubs, tapered in two directions. The arch-vent stubs, viewed in the radial direction are so unobtrusive as to be cosmetically acceptable in a finished tire.

Abstract: The quality and useful life of curing bladders used in standard "Bag-O-Matic" tire vulcanizing presses is greatly improved by replacing the standard split two-piece core of the bladder mold with a unitary core which forms a disc-like rubber diaphragm below the core and integral with the rubber curing bladder at the periphery of the core. A unique base plate fits in the lower mold half below the core and has a grooved upper surface to hold the diaphragm in place so that the core can be removed manually or automatically with the assistance of internal air pressure.