Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Patent
1989-07-26
1991-12-24
Ball, Michael W.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
156 87, 156125, 2643283, 264315, 425 46, 425812, 425 281, 249141, B28B 716
Patent
active
050750674
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. The arch-vent stubs, when viewed in the radial direction towards the center of the tire, are so unobtrusive as to be cosmetically acceptable in a finished tire. The upper surface of the arch-vent is close to the inner surface of the tread ring and essentially horizontal, while the lower surface of each arch-vent is inclined at an angle in the range from 30.degree.-50.degree. to the horizontal plane, but in opposite directions. An angle in this range provides surprising strength in the base area of the arch-vent stub so that, upon stripping the tire from the mold, the arch-vent bridge of cured rubber breaks cleanly and reliably at the narrowest and weakest point in the bridge.
REFERENCES:
patent: 1880430 (1932-10-01), Furnas
patent: 3467989 (1969-09-01), Youngblood et al.
patent: 4023268 (1977-05-01), Momchilov
patent: 4881881 (1989-11-01), Rockarts et al.
Bartley Donald R.
Rockarts Rene L.
Ball Michael W.
Csontos Alan A.
Lobo Alfred D.
Lorin Francis J.
The Uniroyal Goodrich Tire Company
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