Method of producing a toroidal road vehicle tire carcass

Abstract: A toroidal road vehicle tire carcass (1) having two annular beads (2) connected by a toroidal reticulated structure (4) defined by a number of elongated reinforcing elements located between and extending substantially radially in relation to the beads (2) is formed from a single continuous cord (5) for forming a succession of substantially identical groups (6) of elongated reinforcing elements, wherein each group (6) is defined by a first (7) and second (8) U-shaped loop having respective open ends (10) and respective closed ends (11) arranged along an annular interconnection line (9) extending centrally in relation to the beads (2); each loop (7, 8) being wound about a respective bead (2), and having an open end (10) engaging the closed end (11) of the other loop (8, 7).

Description: The present invention relates to a method of producing a toroidal road vehicle tire carcass. More specifically, the present invention relates to a straightforward, low-cost method of producing a toroidal radial tire carcass comprising two annular beads connected by a toroidal reticulated structure in turn comprising a number of elongated reinforcing elements connecting and extending substantially radially in relation to the beads. According to EP-A-0 549 869, which is considered herein under the terms of Article 54(3) EPC, a road vehicle tire carcass, comprising two annular beads connected by a toroidal reticulated structure defined by a number of elongated reinforcing elements extending between and substantially radially in relation to the beads, is produced by using at least one continuous cord for forming a continuous series of oppositely orientated U-shaped loops, the loops in both series being so connected as to weave a substantially tubular structure enclosing the two beads. According to the present invention, there is provided a method of producing a toroidal road vehicle tire carcass comprising two parallel annular beads, and a toroidal reticulated structure connecting the two beads and comprising a number of elongated reinforcing elements located between and extending substantially radially in relation to the beads; said elongated reinforcing elements being formed from a single 7 continuous cord wound in such a manner as to form a succession of substantially identical groups of elongated reinforcing elements, wherein each group is defined by a first and second U-shaped loop having respective open ends and respective closed ends arranged side by side along an annular interconnection line lying substantially in a plane between the bead planes; each loop being wound about a respective said bead, and having the open end engaging the closed end of the other loop. The present invention will now 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 carcass formed using the method according to the present invention; Fig.2 shows a spreadout view of the Fig.1 carcass portion. Number 1 in Fig.1 indicates a toroidal road vehicle tire carcass. Carcass 1 comprises two annular beads 2 with respective 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 single continuous cord 5 wound in such a manner as to form a succession of substantially identical groups 6 of said reinforcing elements, wherein each group 6 is defined by a first and second U-shaped loop 7 and 8 oppositely oriented in relation to annular interconnection line 9. Line 9 lies substantially in a plane between the planes of beads 2, and, as in the example shown, loops 7 and 8 are preferably of the same length, so that line 9 is located substantially halfway between the planes of beads 2. Each loop 7, 8 presents an open end 10 and a closed end 11, and is wound about respective bead 2 and filler 3 so as to form a respective tubular annular structure 12 enclosing respective bead 2 and defining substantially half of structure 4. More specifically, each loop 7, 8 is arranged with both ends 10 and 11 along line 9, and with open end 10 engaging closed end 11 of the other loop 8, 7, so as to connect tubular structures 12 by means of a succession of interconnections 13 along line 9. Carcass 1 as described above is preferably formed on a supporting frame 14 comprising an inner portion 15 defined by beads 2 and forming the skeleton of carcass 1; and a removable auxiliary outer portion 16 defined by two rings 17, each consisting, in known manner not shown, of a number of releasably-connected curved segments. Portion 16 is located between and radially outwards in relation to beads 2, so as to define, with beads 2, two annular openings 18. When forming structure 4, frame 14 is preferably rotated about its axis, and structure 4 is woven about beads 2 and outwards of portion 16. More specifically, each loop 7, 8 presents an intermediate portion wound about respective bead 2, while respective open end 10 and closed end 11 extend respectively outwards of frame 14 and through respective opening 18 up to respective interconnections 13 outwards of portion 16.

Claims: A method of producing a toroidal road vehicle tire carcass (1) comprising two parallel annular beads (2), and a toroidal reticulated structure (4) connecting the two beads (2) and comprising a number of elongated reinforcing elements located between and extending substantially radially in relation to the beads (2); said elongated reinforcing elements being formed from a single continuous cord (5) wound in such a manner as to form a succession of substantially identical groups (6) of elongated reinforcing elements, wherein each group (6) is defined by a first (7) and second (8) U-shaped loop having respective open ends (10) and respective closed ends (11) arranged side by side along an annular interconnection line (9) lying substantially in a plane between the bead planes; each loop (7, 8) being wound about a respective said bead (2), and having the open end (10) engaging the closed end (11) of the other loop (8, 7). A method as claimed in Claim 1, characterized by the fact that said continuous cord (5) is so wound that the loops (7, 8) in each said group (6) are substantially the same length, and so that said interconnection line (9) is located substantially centrally in relation to the bead planes. A method as claimed in Claim 1 or 2, characterized by the fact that it comprises an initial stage consisting in forming a supporting frame (14) for the carcass (1); said frame (14) comprising an inner portion (15) defined by the two beads (2) and forming the skeleton of said carcass (1), and a removable auxiliary outer portion (16) located between and radially outwards in relation to the beads (2); said reticulated structure (4) being woven about the beads (2) and outwards of the auxiliary outer portion (16). A method as claimed in Claim 3, characterized by the fact that each said loop (7, 8) is wound about a respective bead (2), and the open and closed ends (10, 11) are drawn towards the interconnection line (9) for forming, with the other loops (7)(8) of the same type in the other said groups (6), a tubular structure (12) woven about the respective bead (2) and connected to the tubular structure (12) of the other bead (2) along said interconnection line (9). A method as claimed in Claim 4, characterized by the fact that said inner and outer portions (15, 16) define two annular openings (18); each said loop (7, 8) comprising an intermediate portion wound about a respective bead (2), the open and closed ends (10, 11) of said loop (7, 8) being wound respectively outwards and through a respective said opening (18).

Inventors: SIEGENTHALER KARL J, SIEGENTHALER, KARL J.
Applicants: BRIDGESTONE CORP, BRIDGESTONE CORPORATION
Application year: 1993
Main classification: B29D30
IPC codes: B60C9, B29K105, B29D30