Sumitomo Rubber Industries Limited

Naoki Sugiyama

Tomoyuki Kujime

Hiroshi Ito

Minoru Nishi

Hiroki Takahashi

Kei Kohara

Masanori Takahashi

Hiroshi Okagawa

Yuichi Takeuchi

Kosuke Nakano

Yuichi Nakano

Tomoharu Torii

Makoto Ohkoshi

Hirotoshi Ohtsuki

The present invention has an object of providing a pneumatic tire that exhibits better uniformity by improving the wire wound body for constituting the bead core. The pneumatic tirecomprises a bead corecomprising a wire wound bodyin which one bead wireis spirally wound in a continuous around a tire rotational axis CL so that a plurality of layers of the bead wire are formed in a radial direction of the tire. The wire wound bodycomprises a first partand a second part. The first partcomprises a plurality of layers of the bead wireeach circumferentially extending with a constant radius from the tire rotational axis CL. The second part comprises a plurality of layers of the bead wireeach circumferentially extending while changing its radius from the tire rotational axis CL.

Pneumatic tire and manufacturing method therefor

A run-flat tire comprises a tread portion, sidewall portions, bead portions, and a carcass ply extending between the bead portions. The sidewall portions are each provided therein with a sidewall reinforcing rubber layer having a crescent-shaped cross sectional shape and disposed on the axially inside of the carcass ply. The sidewall portions are each provided in the axially outer surface thereof with a rim protector which projects radially outward most on the radially outside of the radially inner edge of the sidewall reinforcing rubber layer. The bead portions are each provided therein with an axially inside core and an axially outside core between which each radially inner edge portion of the carcass ply is secured. When measured along a normal line drawn normally to the carcass ply from an apex of the rim protector, the thickness of the sidewall reinforcing rubber layer is in a range of from 29% to 35% of the thickness of the tire.

Run-flat tire

Provided are: vent pieces, which can easily be added later and with which the occurrence of spew can be suppressed without restriction in the locations where the vent pieces can be orderly arranged in vulcanized molding of a pneumatic tire; and a manufacturing method for pneumatic tire in which vulcanization molding of a raw cover is performed by using a vulcanization mold in which said vent piece has been embedded. A vent piece, which is used by being embedded in a prepared hole for air vent provided on the inner surface of a pneumatic tire vulcanization mold, is a cylinder without a hole in the axial direction and is configured to perform air vent from a gap formed between the vent piece and the side surface of the prepared hole. A vent piece has a saw cut extending in the axial direction formed on the side surface of the cylinder.

Vent piece and manufacturing method for pneumatic tire

It is a run-flat tireprovided with a carcassextending from a tread portionthrough a sidewall portionto a bead corein a bead portion, and a side-reinforcement rubber layerdisposed inside the carcassin the sidewall portionand having a substantially crescent-shaped cross-section. In a tire meridian cross section including the tire rotational axis under a normal state such that the tire is mounted on a normal rim, inflated to a normal internal pressure and loaded with no load, the tire inner-cavity surfaceincludes a side inner-cavity surface. A distance in the tire radial direction of the side inner-cavity surfacefrom a bead toeof the bead portionis in a range of 0.4 times to 0.9 times the length H in the tire radial direction of the tire inner-cavity surface. The side inner-cavity surfaceincludes a smooth surfacewhich does not have unevenness, and the total surface area of the smooth surfaceis more than 90% of the total area of the side inner-cavity surface

Tire including: a tread; a pair of sidewalls extending substantially inward radially from ends of the tread; a pair of beads positioned substantially radially inwardly of the sidewalls; and a clinch portion extending from the sidewalls to the beads. A concave curved surface extends on an outer surface of the clinch portion in a circumferential direction. A convex curved surface formed on a radially outer side end of a rim flange is engageable with the concave curved surface. A ratio R/R of curvature radius Rof the concave curved surface to a curvature radius R of the convex curved surface of the rim flange satisfies 1.7&#x2264;R/R&#x2264;2.5. The curvature radii Rand R of the concave and convex curved surfaces, respectively, are each a radius of curvature of an arc on a cross-section taken along a plane including a tire center axis.

Heavy duty pneumatic tire

To prevent rubber from becoming membrane-like mold flash between mating faces and being adhered. It is a rigid core for forming a tire which comprises an annular core main body provided in an outer surface thereof with a tire molding surface for forming a raw tire. The core main body is composed of a plurality of core segments which are divided in a circumferential direction, and each of the core segments has both circumferential end surfaces as mating faces, and the mating faces adjacent to each other in the circumferential direction are butted to each other so as to form the core main body. Each of the mating faces is provided with a border recess extending along an outer peripheral edge of the mating face and formed by cutting away a corner between the tire molding surface and the mating face.

Rigid core for forming tire and tire manufacturing method using the same

A pneumatic tire is provided with a carcass configured from at least one carcass ply. The carcass ply is formed by arranging, in the tire circumferential direction, rectangular sheet-shaped ply pieces, each having a radial direction length larger than a tire circumferential direction length. In each of the ply pieces, carcass cords are arranged parallel to each other in the longitudinal direction, and adjacent ply pieces at least partially overlap with each other in the tire circumferential direction, and in each of the ply pieces, the distance (Pe) between the carcass cords in at least one side edge portion in the circumferential direction of the ply piece, is larger than the distance (Pc) between the carcass cords in a central portion of the ply piece.

Pneumatic tire with rectangle-sheet-shaped carcass ply pieces

The method for molding a bead portion for a green tire includes a bead core supporting step for supporting the bead core through a carcass ply upon expanding a diameter of a bead core supporter including a seating surface for supporting a radially inner surface of the bead core. Since the bead core supporter comprises an outer piece outside of the seating surface in a tire axial direction that rises up towards outside in the radial direction with a clearance between the same and the bead core, that is larger than the thickness of the carcass ply, it is possible to flip a carcass outer region up, that is outside in the tire axial direction than a sandwiched region of the carcass ply, sandwiched and held between the seating surface and the bead core, and to deform the carcass outer region into an outer inclined piece that is inclined and extended towards radially outside without including any partially bent portions. It further includes a curving step of pressing the outer inclined piece inward in the tire axial direction by using a ply winding ring for curving the same towards the outside surface and the radially outer surface of the bead core, and a pressing step of pressing a tip end portion of the curved outer inclined piece towards the radially outer surface of the bead core by using a pressing roller.

Method for molding bead portion of green tire and bead portion molding device

A heavy duty pneumatic radial tire includes a carcass ply, in which a ply folding portion folding a bead core is successively disposed in a ply body. The ply folding portion includes a main portion folded along the bead core, and a winding-up portion extending continuously to the main portion and apart from the bead core. The winding-up portion extends with an inclination of an angle &#x3b8; in a direction in which a diameter is increased inward in the tire axial direction, the angle &#x3b8; being set to 20 to 65 degrees with respect to an upper surface in the radial direction of the bead core, a distance La from the upper surface in the radial direction of the bead core at the inner end point of the winding-up portion being set to 5 mm to 15 mm, and a distance Lb between the inner end point of the winding-up portion and the ply body being set to 1 mm to 5 mm.

Growing community of inventors

Kobe, Japan

Naoki Sugiyama