Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
1999-12-10
2001-08-21
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C264S334000, C425S036000, C425S044000
Reexamination Certificate
active
06277317
ABSTRACT:
RELATED APPLICATIONS
This application is related to International Application Ser. No. PCT/US97/04859 entitled PNEUMATIC TIRES WITH VULCANIZED INNERLINER AND METHOD FOR UTILIZING INNERLINER filed Mar. 25, 1997 and having a common assignor with the present application.
1. Technical Field
The present invention relates to an improved tire mold construction and to an improved method of building tires that incorporates the advantages achieved through the use of the new constructional design for the tire mold. More particularly, the present invention relates to an improved method of building tires with a tire mold for shaping and curing of tires without a tire bladder.
2. Background of the Invention
To better understand the advantages and improvements achieved with the present invention, a brief discussion of tire construction and building procedures follows. A pneumatic tire is typically constructed by applying various components, or plies of the tire as flat stock, upon a rotating tire building drum to form a hollow, toroidal shaped green or uncured tire. The order of applying the components is as follows: first, an innerliner is wrapped upon the tire building drum; the innerliner is followed by carcass plies containing tire reinforcement, the carcass plies are followed (not necessarily in the following order) by the beads, apexes, chafers, side walls, belts and tread. The components are then expanded and formed into a toroidal shaped, green tire assembly, in a manner well known in the art. The green tire assembly is then removed from the tire building drum and placed into a shaping and vulcanizing mold having the shape of the finished tire. The mold is sealed and the toroidal shaped green tire assembly is heated and expanded radially outward into the mold periphery by injecting pressurized gas or fluid into a curing bladder mounted within the mold and disposed within the green tire assembly. As the curing bladder expands, it forces the tread and sidewalls of the green tire assembly into contact with the heated mold walls to shape and vulcanize the green tire assembly into a fully vulcanized tire. During the radial expansion of the green tire assembly within the shaping and vulcanizing mold, the toroidally shaped plies expand radially outward to dimensions slightly beyond those of the original green tire assembly. Therefore, the bladder is conventionally made of an expandable elastomeric material, usually butyl rubber, for resistance to steam.
During the production of tires on an assembly line, the curing bladder within the shaping and vulcanizing mold periodically wears out or fails. This has proven to be a difficult problem to overcome because of the harsh environment and demanding operating conditions to which the elastomeric bladder is subjected, being part of an assembly line that is operating around the clock and throughout the year. For example, the bladder is located in a heated mold and is constantly being expanded and contracted for each tire built. Moreover, the bladder is being subjected to high temperature, pressurized gas or fluid, such as steam, which is used to expand the bladder.
The high paced manufacturing methods of building tires on an assembly line is limited by the time required to shape and vulcanize each green tire in the tire molds. The tire molds are very expensive and typically several tire molds are provided for each tire building drum. Still, the primary cause for downtime of the assembly line is the need to replace a defective or worn bladder in a tire mold. This fact, combined with the expense of purchasing and maintaining each of the tire molds, results in a concentrated effort by the tire industry to keep the tire molds operational. This effort is very expensive given the reduced tire production during the significant downtime that a tire mold is not operational, the labor cost for installing a new curing bladder and putting the tire mold back into operation, and the cost of manufacturing or purchasing the bladders themselves.
The tire industry has tried to eliminate the need for a curing bladder used in tire production. For example, U.S. Pat. No. 3,143,449 ('449) discloses a bladderless tire mold for curing and shaping a green tire. The green tire has an unvulcanized, barrel shaped, spliceless innerliner for completely sealing the inside of a green tire against the escape of pressurized fluid into the tire body during the vulcanizing operation in a tire vulcanizing mold. The '449 patent discloses that by eliminating the splice in the tire innerliner, the inflation fluid in a bladderless mold was unable to escape through the splice into the body of a green tire being molded and vulcanized in a tire vulcanizing mold. However, the mounting of the green tire into the mold requires a complicated mold construction that permitted the injection of inflation fluid into the tire body being molded in the bladderless mold to the desired shape.
Also pertinent to the present invention, there was disclosed in U.S. Pat. No. 4,166,883 ('883) a bladderless mold for curing tires. A bead sealing ring is inserted between the beads of the tire before the tire mold is closed, and serves as a gasket. The ring which is typically made of steel or other hard elastomeric material can include extension that are pressed inwardly by the tire as the tire mold is closed to shape the bead and form a tight seal, as illustrated in FIG. 7 of the '883 patent. The sealing ring is typically made of steel or other hard material which is flexible to the extent that it can press inwardly upon the tire to shape the bead and form a tight seal when the tire mold is closed. The problem with this tire mold construction is the degree of mechanical complexity required to insert the sealing ring between the beads of the tire after the green tire has been placed within the tire mold but before it is closed. Another significant design consideration relating to the sealing ring of the '833 patent is that the extension permit deflection of the outer surface of the member 29 from the position shown in dotted lines, to that shown in full lines, see FIG. 7 and the discussion on column 5 lines 13 through 18 of the '833 patent. Fundamentally, while the '883 patent has removed the bladder from the mold, it still requires a rather complicated mechanism for sealing the tire during the shaping and vulcanization which increases the complexity and limits the speed of the tire mold operation.
U.S. Pat. No. 4,181,483 shows an apparatus for the bellowless vulcanization of tire blanks including an elastomeric ring to seal against the tire bead.
Another design, as shown in U.S. Pat. No. 1,982,674 ('674), is the provision of a sealing ring with flexible side members that seal against the bead portions of the tire to prevent the escape of the pressurized gas or fluid. As with the '883 patent, the construction of the sealing ring disclosed in the '674 patent is cumbersome because it is mounted into the green tire prior to the placement of the green tire and sealing ring assembly into the tire mold. This assembly procedure is labor intensive and not suitable for modern, automated assembly line techniques. Also, the side members are an integral part of a rather complex sealing ring, as seen in FIG. 3, which is more prone to failure because of the harsh environment in which it is operated.
It is apparent that there is still a need to provide novel bladderless tire mold constructions and methods of operation for manufacturing tires on high speed assembly lines that reduce: a) the time and/or labor costs for mounting a green tire in a shaping and vulcanization mold; b) the downtime when a tire mold is not operational; and c) the labor and material cost for installing a new curing bladder and putting the tire mold back into operation.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a bladderless tire mold construction and method of inserting a green tire and removing a vulcanized tire from the tire mold being as defined in one or more
Rex William Allen
Stoila George Michael
Vannan, Jr. Frederick Forbes
Wolbert Harold Aloysius
Yovichin Albert James
Cohn Howard M.
The Goodyear Tire & Rubber Company
Vargot Mathieu D.
LandOfFree
Method for building pneumatic tires in an improved tire mold does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for building pneumatic tires in an improved tire mold, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for building pneumatic tires in an improved tire mold will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2458284