SIPE GEOMETRY FOR IMPROVED BUFFING OF TREAD BAND
A mold for a tread layer having tread-forming side and sole-forming side, the sole-forming side having a plurality of mold elements extending there from toward the tread-forming side. Either the mold elements or the sole-forming side of the mold is configured to create a tread layer having a recessed tread element such as an incision, lateral groove, longitudinal groove or other void on the sole side of the tread layer that enables the edges of the recessed tread element to obtain full coverage when subjected to an abrasion process.
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This application claims priority to, and the benefit of, U.S. patent application Ser. No. 12/446,479 filed on Apr. 21, 2009 with the United States Patent and Trademark Office and International Application No. PCT/US06/45726 filed on Nov. 29, 2006 with the United States Receiving Office, each of which are hereby incorporated by reference.
FIELD OF THE INVENTIONThe present invention is in the field of re-treaded tires.
DESCRIPTION OF THE RELATED ARTWhen tires become worn, they can be restored with new tread band or tread layer. Large truck tires are typically retreaded as part of a routine tire-management program. The carcass of a truck tire is expected to last several hundred thousand miles and be amenable to having a new tread layer adhered to it several times. New truck tires are quite expensive and are therefore bought with the expectation that their high initial costs are offset by the long service life of the carcass and the low comparative cost of retreading.
A variety of procedures and different types of equipment are available for use in recapping or retreading pneumatic tires. One of the first steps in retreading a worn tire is to remove existing tread layer material from the tire carcass by a sanding procedure known as buffmg. Next a layer of what is known as “cushion gum” is applied to the carcass. This layer of extruded, uncured rubber may be stitched or adhesively bonded to the carcass. Next, a tread layer is applied atop the layer of cushion gum. In the cold recapping process, the tread layer is cured rubber, and has a tread pattern already impressed in its outer surface. The tire is then placed in an autoclave, and heated under pressure for an appropriate time to induce curing of the gum layer, and binding of the gum layer to the inner or sole side of the tread layer and the carcass. The term “cure” refers to the formation of cross-links between the elastomer molecules in the rubber compound. It is further noted that there are various methods of bonding the tread layer to the carcass such as the use of adhesives, bonding agents, cushion gums, etc., and that all of the methods known in the art are included when referring to the term “bonding interface”.
A common problem with tires including retreads, is that as the tire wears, the traction-providing elements also wear, until eventually the elements are substantially worn away. The result can be a significant reduction in traction for the worn tire. Efforts have been made to develop a tread layer that has tread elements cut into the sole side (the side facing the cushion gum layer) of the tread layer. The term “tread elements” refers to incisions, lateral grooves, and/or longitudinal grooves or any other void formed in the tread layer. The term “mold elements” are the parts of the mold that create the tread elements in the tread layer, such as for example a fin. Tread elements molded into the sole side of the tread layer appear as the tire wears, giving improved worn traction over the life of the retread and allowing the tire to be removed from service later in life.
SUMMARY OF THE INVENTIONA particular embodiment of the present invention includes a tread layer for a tire, the tread layer comprising: a tread layer body having a tread side and a sole side; a plurality of recessed tread elements molded from the sole side of the tread body; wherein the plurality of recessed tread elements each has a protrusion extending from a first inner surface of the recessed tread element toward an opposing surface of the tread element.
Another particular embodiment of the present invention includes a tread layer for a tire, the tread layer comprising: a tread layer body having a tread side and a sole side; a plurality of protrusions extending from the sole side of the tread layer, wherein the recessed tread elements each abut at least one of the protrusions.
Another particular embodiment of the present invention includes a method of molding a tread layer comprising the steps of: molding a tread surface on a tread side of the tread layer; molding a plurality of recessed tread elements from a sole side of the tread layer; molding a plurality of protrusions extending from the sole side of the tread layer, wherein the recessed tread elements each abut at least one of the protrusions.
Another particular embodiment of the present invention includes a mold for curing a tread layer comprising: a first side of the mold having a tread-forming surface; a second side of the mold having a sole-forming surface; wherein the second side of the mold comprises a plurality of mold elements extending from the sole-forming surface toward the first side of the mold; wherein the second side of the mold has at least one recess in the sole-forming surface abutting the at least one mold element.
Another particular embodiment of the present invention includes a mold for curing a tread layer comprising: a first side of the mold having a tread-forming surface; a second side of the mold having a sole-forming surface; wherein the second side of the mold comprises a plurality of mold elements extending therefrom toward the first side of the mold; at least a portion of at least one mold element having a variable cross-sectional thickness.
Another particular embodiment of the present invention includes a mold for curing a tread layer comprising: a first side of the mold having a tread-forming surface; a second side of the mold having a sole-forming surface; wherein the second side of the mold comprises a plurality of mold elements extending therefrom toward the first side of the mold and wherein the second side of the mold has at least one recess in the sole-forming surface abutting the at least one mold element.
These and other advantages will be apparent upon a review of the detailed description of the invention.
Referring now to
The production of the tread layer 40 is shown in
When the tread layer 40 is removed from the mold 50 as shown in
Although not shown, the sole side surface 46 is typically covered with mold release agents upon removal of the tread layer 40 from the mold 50. Accordingly, the sole side surface 46 must be treated to remove the release agents from the surface. One such treatment method involves adding a texture to the sole side surface 46.
Referring now to
The result is best shown in
In order to improve the endurance of the retreaded tire 10 the sole side of the tread layer should be completely roughened. Referring now to
Other embodiments of the mold 250, 350 and corresponding tread layer 40 are shown in
While the exemplary embodiments described and shown herein include bumps or protrusions having a rounded shape, the invention is not meant to be limited to such shapes as the shape may include any suitable shape including, for example, triangular, rectangular, oval or parts of these shapes.
In the previous embodiments, recesses were formed in the mold surface to ensure complete roughening treatment of the sole side surface having recessed tread elements. In the next embodiments of
These configurations of mold elements 456, 556, 656, 756, 856 result in blocking material as protrusions 447, 547, 647, 747, 747′, 847 in the recessed tread element inner wall that prevent an edge from deflecting (e.g., as best seen in
All shapes and geometries of the protrusions are acceptable as long as the protrusions can be pushed against an opposing wall during the abrasion process to prevent the recessed tread element edge from deflecting. As illustrated above, the opposing wall may be an opposing wall of the recessed tread element or an opposing wall of another protrusion from the recessed tread element wall, as best seen in
While this invention has been described with reference to preferred embodiments, thereof, it shall be understood that such description is by way of illustration and not by way of limitation. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.
Claims
1. A tread layer for a retreaded tire, the tread layer comprising:
- a tread layer body having a thickness defined by an outer surface and an inner surface of the tread layer body, the outer surface arranged on a tread side of the tread layer and the inner surface arranged along a sole side of the tread layer and forming an outer bonding surface of the tread layer body for bonding the tread layer body to a tire carcass, the tread side having a width that is narrower than a width of the sole side;
- a recessed tread element comprising a void formed into the sole side of the tread layer;
- a protrusion extending outwardly from the inner surface of the tread layer body and away from the tread side, wherein the protrusion is arranged along the sole side to abut the recessed tread element.
2. The tread layer of claim 1, wherein the inner surface of the tread layer is a texturized inner surface, the protrusion extending outwardly from the texturized inner surface.
3. The tread layer of claim 2, wherein the first protrusion extends outwardly from the inner surface by a distance forming a height, the height of first protrusion being at least 0.2 mm to about 5 mm.
4. The tread layer of claim 1, wherein the protrusion has a rounded cross-sectional form.
5. The tread layer of claim 1, wherein the protrusion is a first protrusion and wherein a second protrusion is arranged on the sold side of the tread layer body and in abutment with the recessed tread element, the second protrusion extending outwardly from the inner surface of the tread layer body and away from the tread side, the first protrusion and the second protrusion being arranged on opposing sides of the recessed tread element.
6. The tread layer of claim 5, wherein each of the first and second protrusions extend outwardly from the inner surface by a distance forming a height, the height of first protrusion being different than the height of the second protrusion.
7. The tread layer of claim 5, wherein the first protrusion extends outwardly from the inner surface by a distance forming a height, the height of first protrusion being at least 0.2 mm to about 5 mm.
8. The tread layer of claim 5, wherein each of the first and second protrusions has a rounded cross-sectional form.
9. The tread layer of claim 1, wherein the protrusions are formed having a height greater than 0.5 mm above the sole side of the tread body.
10. The tread layer of claim 1, wherein the recessed tread element is a sipe or incision.
11. The tread layer of claim 1 further comprising: a tire carcass, wherein the sole side of the tread layer is bonded to the tire carcass.
12. The tread layer of claim 1, wherein the recessed tread element is a sipe or an incision.
13. A method of providing a tread layer for retreading a tire comprising the steps of:
- providing a tread layer for a tire, the tread layer including: a tread layer body having a thickness defined by an outer surface and an inner surface of the tread layer body, the outer surface arranged on a tread side of the tread layer and the inner surface arranged along a sole side of the tread layer and forming an outer bonding surface of the tread layer body for bonding the tread layer body to a tire carcass, the tread side having a width that is narrower than a width of the sole side; a recessed tread element comprising a void formed into the sole side of the tread layer; and, a protrusion extending outwardly from the inner surface of the tread layer body and away from the tread side, wherein the protrusion is arranged along the sole side to abut the recessed tread element.
14. The method of claim 13, wherein the inner surface of the tread layer is a texturized inner surface, the protrusion extending outwardly from the texturized inner surface.
15. The method of claim 13, wherein the protrusion has a rounded cross-sectional form.
16. The method of claim 13, wherein the protrusion is a first protrusion and wherein a second protrusion is arranged on the sold side of the tread layer body and in abutment with the recessed tread element, the second protrusion extending outwardly from the inner surface of the tread layer body and away from the tread side, the first protrusion and the second protrusion being arranged on opposing sides of the recessed tread element.
17. The method of claim 16, wherein each of the first and second protrusions extend outwardly from the inner surface by a distance forming a height, the height of first protrusion being different than the height of the second protrusion.
18. The method of claim 16, wherein each of the first and second protrusions has a rounded cross-sectional form.
19. The method of claim 13 further comprising the step of:
- bonding the tread layer to a tire carcass to form a retreaded tire.
20. The method of claim 13, where the tread layer provided in the step of providing a tread layer is formed by a molding process.
Type: Application
Filed: Sep 14, 2012
Publication Date: Jan 24, 2013
Applicant: MICHELIN RECHERCHE ET TECHNIQUE S.A. (GRANGES-PACCOT)
Inventors: Juan-Pablo Gallego (Samut Prakan), Nathan J. Panning (Simpsonville, SC)
Application Number: 13/618,533
International Classification: B60C 11/11 (20060101); B29D 30/06 (20060101); B60C 11/12 (20060101);