Method of producing a toroidal road vehicle tire carcass, and carcass produced thereby

Abstract: A toroidal road vehicle tire carcass (1), comprising two annular beads (2) connected by a toroidal reticulated structure (4) defined by a number of elongated reinforcing elements extending between and substantially radially in relation to the beads (2), is produced using at least one continuous cord (5)(6) for forming a first and second continuous series of oppositely-oriented U-shaped loops (7, 8); the loops (7, 8) in both series being so connected as to weave a substantially tubular reticulated structure (4) enclosing the two beads (2).

Description: The present invention relates to a method of producing a toroidal road vehicle tire carcass. In general, radial tires comprise a radial carcass in turn comprising two annular beads and a toroidal reticulated structure connecting the beads to each other. The noted reticulated structure is normally defined by a number of elongated reinforcing elements connecting the beads and extending substantially radially in relation thereto. The above elongated reinforcing elements normally consist of the reinforcing wires or cords of a ply that is arranged, at the beginning, on a cylindrical surface to define e tube, on which the two beads are mounted so that an intermediate portion of the tube extends between the beads themselves, and two end portions of the tube extend outside the respective beads. Then the noted end portions are turned up about the relevant beads and, at the same time, the beads are moved toward one another to shape the ply to a substantially toroidal carcass. In general, as disclosed in Italian Patent No. 1162853, very expensive machinery is needed to turn up the end portions of the tubular ply about the beads, and to move the beads toward one another to shape the intermediate portion of the carcass; and the above machinery highly affects the manufacturing costs of a radial carcass. It is an object of the present invention to lower the above manufacturing costs by providing a straightforward, low-cost method of producing a toroidal radial tire carcass. According to the present invention, there is provided a method of producing a toroidal road vehicle tire carcass comprising two annular beads, and a toroidal reticulated structure connecting the two beads and comprising a number of elongated reinforcing elements between and extending substantially radially in relation to the beads; said method being characterized by the fact that said elongated reinforcing elements are formed using at least one continuous cord wound into a first and second continuous series of oppositely-oriented U-shaped loops, and by connecting the loops in said two series in such a manner as to weave a substantially tubular said toroidal reticulated structure enclosing the two beads. The above method preferably comprises an initial stage consisting in forming a supporting frame for the carcass; said frame comprising an inner portion defined by the two beads and forming the skeleton of the carcass; and a removable auxiliary outer portion between and radially outwards in relation to the beads; said reticulated structure being woven about the two beads and outside the auxiliary outer portion. According to a preferred embodiment of the above method, the loops in said two series are connected by inserting each loop in each series through a respective loop in the other series. In particular, each loop is preferably formed by inserting an intermediate U-shaped cord portion through a respective loop formed from another intermediate cord portion, so as to form a link between said two loops and produce a "bouclé" type reticulated structure. The present invention also relates to a carcass formed using the above method. According to the present invention, there is provided a toroidal road vehicle tire carcass comprising two annular beads, and a reticulated structure connecting the two beads and in turn comprising a number of reinforcing elements extending between and substantially radially in relation to the beads; characterized by the fact that said elongated reinforcing elements are formed from at least one continuous cord wound into a first and second continuous series of oppositely-oriented U-shaped loops, each connected to a respective loop in the other series to weave a substantially tubular said toroidal reticulated structure enclosing the two beads. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Fig.1 shows a schematic view in perspective of a portion of a preferred embodiment of the carcass according to the present invention; Fig.2 shows a plan view of the carcass portion in Fig.1. Number 1 in Fig.1 indicates a toroidal road vehicle tire carcass. Carcass 1 comprises two annular beads 2 with respective bead fillers 3; and a toroidal reticulated structure 4 connecting beads 2 and in turn comprising a number of reinforcing elements extending between and substantially radially in relation to beads 2. In the example shown, said reinforcing elements are formed from a first and second continuous cord, 5 and 6, wound so as to form a first and second continuous series of oppositely-oriented U-shaped loops 7 and 8. According to a variation not shown, cords 5 and 6 are connected to form a single continuous cord. Alternatively, according to further variations not shown, the carcass may be divided into a number of sectors, each formed using one or two cords. Each loop 7,8 is linked at 9 to a respective loop 8, 7 in the other series, to weave a substantially tubular structure 4 enclosing beads 2. Each link 9 in loops 7 and 8 is located along the inner surface of reticulated structure 4, close to respective bead 2, and is formed by inserting one of loops 7, 8 through the other loop 8, 7, so as to form a so-called "bouclé" structure 4. Each loop 7, 8 comprises a first portion 10 extending from link 9 about adjacent bead 2, and having two substantially parallel branches; and a second U-shaped end portion 11 wound towards the other bead 2. Carcass 1 as described above is formed on a supporting frame 12 comprising an inner portion 13 defined by beads 2 and forming the skeleton of carcass 1; and a removable auxiliary outer portion 14 defined by two rings 14a, each consisting of a number of curved segments connected in releasable manner (not shown). Portion 14 is located between and radially outwards in relation to beads 2, so as to define, with beads 2, two annular openings 15. During the formation of structure 4, frame 12 is preferably rotated about its axis, and structure 4 is woven about beads 2 and outside portion 14. In particular, as already stated, links 9 are arranged along the inner surface of structure 4, and the first portion 10 of each loop 7, 8 extends from a respective link 9 and is wound outwards about a respective adjacent first bead 2, while the second portion 11 is wound towards the second bead 2, outside portion 14, and through the opening 15 adjacent to second bead 2, up to a further link 9 adjacent to second bead 2. Each of loops 7 and 8 is therefore wound about a respective 2, extends over the outside of frame 12 and through opening 15 opposite respective bead 2 in relation to portion 14, so as to produce a woven tubular structure 4 enclosing beads 2. In connection with the above, it should be pointed out that, as with any bouclé structure, each loop 7, 8 is produced by winding an intermediate portion of cord into a U. In other words, structure 4 may be produced using one cord 5, 6 with one free end, and by winding a first intermediate portion of said cord 5, 6 in a U to produce a first loop 7, 8, and then winding further intermediate portions of cord 5, 6 into further loops 7, 8 on the opposite side of said first intermediate portion in relation to said free end. That is, structure 4 may be produced from a so-called "infinite" cord 5, 6, e.g. a cord 5, 6 produced continuously, as it is used up, by a die (not shown) adjacent to frame 12.

Claims: A method of producing a toroidal road vehicle tire carcass (1) comprising two annular beads (2), and a toroidal reticulated structure (4) connecting the two beads (2) and comprising a number of elongated reinforcing elements between and extending substantially radially in relation to the beads (2); said method being characterized by the fact that said elongated reinforcing elements are formed using at least one continuous cord (5, 6) wound into a first and second continuous series of oppositely-oriented U-shaped loops (7, 8), and by connecting the loops (7, 8) in said two series in such a manner as to weave a substantially tubular said toroidal reticulated structure (4) enclosing the two beads (2). A method as claimed in Claim 1, characterized by the fact that two continuous cords (5, 6) are employed; each said continuous series of loops (7, 8) being produced by winding a respective said continuous cord (5, 6). A method as claimed in Claim 1 or 2, characterized by the fact that it comprises an initial stage consisting in forming a frame (12) supporting said carcass (1); said frame (12) comprising an inner portion (13) defined by the two beads (2) and forming the skeleton of said carcass (1), and a removable auxiliary outer portion (14) between and radially outwards in relation to the beads (2); said reticulated structure (4) being woven about the two beads (2) and outside said auxiliary outer portion (14). A method as claimed in Claim 3, characterized by the fact that the loops (7, 8) in said two series are connected by inserting each loop (7, 8) in each series through a respective loop (8, 7) in the other series. A method as claimed in Claim 4, characterized by the fact that each loop (7, 8) is formed by inserting an intermediate U-shaped portion of cord (5, 6) through a respective loop (8, 7) formed from a further intermediate portion of cord (5, 6), so as to form a link (9) between said two loops (7, 8) and produce a "bouclé" type reticulated structure (4). A method as claimed in Claim 5, characterized by the fact that each said link (9) is formed inside said frame (12). A method as claimed in Claim 6, characterized by the fact that each said link (9) is formed close to a respective said bead (2). A method as claimed in any one of the foregoing Claims from 3 to 7, characterized by the fact that said inner (13) and outer (14) portions define two annular openings (15); each said loop (7, 8) comprising a first (10) and second (11) portion; said first portion (10) comprising two substantially parallel branches, and being wound, as of a respective loop (8, 7) in the other series, outwards about a respective bead (2) and outside one of said openings (15); said second portion (11) being a U-shaped end portion, which is wound towards the other bead (2) and through the other said opening (15). A toroidal road vehicle tire carcass (1) comprising two annular beads (2), and a reticulated structure (4) connecting the two beads (2) and in turn comprising a number of reinforcing elements extending between and substantially radially in relation to the beads (2); characterized by the fact that said elongated reinforcing elements are formed from at least one continuous cord (5, 6) wound into a first and second continuous series of oppositely-oriented U-shaped loops (7, 8), each connected to a respective loop (7, 8) in the other series to weave a substantially tubular said toroidal reticulated structure (4) enclosing the two beads (2). A carcass as claimed in Claim 9, characterized by the fact that said elongated reinforcing elements are formed from at least two continuous cords, each wound into a respective said continuous series of loops (7, 8). A carcass as claimed in Claim 9 or 10, characterized by the fact that each loop (7, 8) in each series is inserted through a respective loop (8, 7) in the other series. A carcass as claimed in Claim 11, characterized by the fact that said reticulated structure (4) is a "bouclé" type structure; each loop (7, 8) being defined by an intermediate U-shaped portion of cord (5, 6) and extending through a respective loop (8, 7) defined by a further intermediate portion of cord (5, 6), so as to form a link (9) between said two loops (7, 8). A carcass as claimed in Claim 12, characterized by the fact that each said link (9) is located along the inner surface of said reticulated structure (4). A carcass as claimed in Claim 12 or 13, characterized by the fact that each said link (9) is located close to a respective said bead (2).

Inventors: SIEGENTHALER KARL J, SIEGENTHALER, KARL J.
Applicants: BRIDGESTONE CORP, BRIDGESTONE CORPORATION
Application year: 1992
Main classification: B29D30
IPC codes: B60C9, B29D30