Method of retreading pneumatic tires
AssigneeDacapo AB
InventorsJan-Eric Lennart Wulker, Gote Bertil Sivert Bohman
Life of this patent
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Abstract
A method for retreading tires using a resilient mold or matrix ring which is normally smaller than a tire body. On its inner side, this ring has an embossing pattern which applies a tread design to a vulcanizable rubber band previously attached to a tire body. The matrix ring is first expanded and then fitted over the tire body with its vulcanizable band in place. Thereafter, the matrix ring is allowed to contract responsive to its inherent tension. The matrix ring thus attached over the tread band is centered on the body while the tire rotates. This whole unit is then heated to a temperature which converts the tread band into a plastic form and embosses the tread design from the matrix ring onto the tread band, which is vulcanized and bonded to the tire body.
Claims13
A method of treading tires in which a vulcanizable camelback tread band is placed on the tread receiving surface of a tire body, said band being made of a material which has a predetermined vulcanizing temperature and which becomes plastic during vulcanization thereof, and in which a peripherally continuous, stretchable, matrix ring mold having an internal, embossing, negative tread pattern is contacted with said band to form said tread pattern thereon, said tread pattern, when said mold is unstretched, having a predetermined normal inner diameter and said mold being made of an elastic material which substantially maintains its elasticity and physical form at least at temperatures up to said vulcanizing temperature, said method comprising the steps of:
- a. placing said camelback tread band on and in contact with the tread receiving surface of a tire body, said tread band having a radial thickness such that the outer diameter thereof when placed on said tire body is greater than said normal inner diameter of said tread pattern;
- b. increasing said inner diameter of said tread pattern to a size at least equal to said outer diameter of said band by stretching and expanding said mold and placing said mold over said tread band on said tire body, the elasticity of said elastic material being sufficient to permit said stretching of said mold without exceeding the elastic limit thereof, whereby said tread pattern is urged by elastic tension to contract until it reassumes said normal inner diameter after the stretching force thereon is terminated;
- c. allowing the expanded matrix ring mold to contract, responsive to said elastic tension, at least until said pattern contacts the exterior surface of said tread band on the tire body;
- and
- d. heating the matrix ring mold, tire body and tread band to a temperature which converts the tread band into a plastic form and thereby permits said mold to further contract and emboss the tread pattern of the matrix ring mold onto the tread band, and which vulcanizes the tread band onto the
Dependencies are inferred from the claim text.