公开(公告)号：JPH1158551A

公开(公告)日：1999-03-02

申请号：JP22454097

申请日：1997-08-21

Applicant: BRIDGESTONE CORP

Inventor： SHIMADA NORIHIRO

IPC: B60C15/04 ,  B29D30/48

Abstract: PROBLEM TO BE SOLVED: To provide a method for manufacturing a bead core for a pneumatic tire tapered at 15 deg. for setting a tapered angle of an inside contour line of a circumscribing contour line of a beam core section of the tire by holding satisfactory rim assemblage. SOLUTION: The method for manufacturing a bead core for a pneumatic tire having the step of supplying one or more continuous steel wires to a rotatably drivable mold forming part of a bead core molding machine to manufacture the core having a plurality of number of winding rows and a plurality of number of winding stages by spirally winding steel wires in close contact with each other comprises the steps of setting a taper of an angle θ of 13.0 to 14.5 deg. to a side of a plurality of steel wires and a rotating axial center X of a mold forming part at an outer peripheral surface of the forming part for forming a first stage of the spiral winding in the close contact with each other, spirally winding the wires plural times in close contact with each other on its outer peripheral surface S1 to form steel wire rows ω11 to ω16 of the first stage, and spirally winding the wires ω31 to ω76 after the second stage ω21 to ω27 and following stages on upper parts of the rows ω11 to ω16 of the first stage, and sequentially repeating the steps.

公开(公告)号：JPH03125605A

公开(公告)日：1991-05-29

申请号：JP26371789

申请日：1989-10-09

Applicant: BRIDGESTONE CORP

Inventor： SHIMADA NORIHIRO

IPC: B60C11/00 ,  B60C11/04 ,  B60C11/12

Abstract: PURPOSE:To prevent the partial wear or the like of circumferential grooves due to the partial wear of a first rubber by setting the repulsive elasticity of a second rubber which forms the inside portion of a tread in the radial direction of a tire lower than that of the first rubber which likely forms the outside portion. CONSTITUTION:A tire used in a new traffic vehicle such as monorail is provided with a large number of circumferential grooves 24 along the circumferential direction of the tire on the tread portion of a tread 18 and also a large number of narrow grooves 29 crossing to an equatorial face 27 at a given angle and at given intervals in the circumferential direction of the tire. In the abovementioned structure, the tread 18 is formed, as a two layer structure, by a first rubber 32 which is located at the outside portion in the radial direction of the tire and likely a second rubber 34 which is located at the inside portion. The repulsive elasticity of the second rubber 34 is set lower than that of the first rubber 32. The growth of a partial wear generated on the first rubber 32 is restrained by the second rubber 34 so that only one part of the circumferential grooves becoming shallow is prevented.

公开(公告)号：JPH0310906A

公开(公告)日：1991-01-18

申请号：JP14418889

申请日：1989-06-08

Applicant: BRIDGESTONE CORP

Inventor： SHIMADA NORIHIRO

IPC: B60C11/00 ,  B60C11/04 ,  B60C11/12

Abstract: PURPOSE:To prevent generation and growth of cracks from the bottoms of sipes by forming a tread rubber with two layers of a wear resistant rubber layer and a crack grow resistant rubber layer while specifying the cut depth of sipes in the crack grow resistant rubber layer. CONSTITUTION:A tire is provided with numerous sipes 4 formed in the tread part 3 having numerous ribs 2 divided by numerous main grooves 1 in peripheral direction while both ends of respective sipes 4 are opened to buttress parts 5. In the above mentioned constitution, a tread rubber 6 for forming the tread part 3 is formed with a wear resistant rubber layer 7 positioned on the surface side of the tread part 3 and a crack grow resistant rubber layer 8 positioned on at least side end parts of the tread part 3 and stuck to a belt 9. The cut depth of respective sipes 4 mentioned above in the crack grow resistant rubber layer 8 is set 10% or more of full depthes of respective sipes 4. Generation and growth of cracks from the bottoms of respective sipes are prevented thereby.

公开(公告)号：JPS63291705A

公开(公告)日：1988-11-29

申请号：JP12527287

申请日：1987-05-22

Applicant: BRIDGESTONE CORP

Inventor： TANAKA MAKOTO ,  MIYAMOTO KENJI ,  SHIMADA NORIHIRO

IPC: B60C11/04 ,  B60C11/12

Abstract: PURPOSE:To make rigidity in the vicinity of open sipes on the end parts of ribs uniform and prevent lopsided abrasion by restricting the amplitude of the zigzag form of a main groove and its groove pitch with respect to the pitch of open sipes which cross a tread having plural ribs. CONSTITUTION:A tire has a tread 15 having plural wide main grooves 12 which extend zigzag in the peripheral direction and plural ribs 13 partitioned by the main grooves 12. And, open sipes 16 are cut across the tread 15 between both tread ends 15a. In this case, the sipe pitch Ps of the open sipes 16 with respect to the peripheral direction C of tire is set at 10-40 mm. Also, the amplitude V12 of the zigzag form of the main groove 12 with respect to the width of tire is set at 1-10 mm. And, the ratio of the groove pitch PG with respect to the peripheral direction C of tire of the main groove 12 to the sipe pitch Ps of the open sipes 16 is set within the range of 1.5-20.

公开(公告)号：JPS63279905A

公开(公告)日：1988-11-17

申请号：JP11544887

申请日：1987-05-11

Applicant: BRIDGESTONE CORP

Inventor： MIYAMOTO KENJI ,  TANAKA MAKOTO ,  SHIMADA NORIHIRO

IPC: B60C11/04 ,  B60C11/12

Abstract: PURPOSE:To prevent the occurrence of deviated wear by a method wherein, in a flat tyre for a vehicle, a plurality of ribs are formed by a plurality of wide main grooves, and a number of shallow cuts, cut down in short of the main groove, are formed at equal distances in a rib next to the outermost rib in an axial direction. CONSTITUTION:Five ribs 25 are formed in a wide main groove 24 in a meandering shape in a tread 22. A width W24 of the main groove 24 is set to approximate 2-10% of a tread width W22. A number of shallow cuts 27 are formed at equal intervals in a rib 25B, being next to an outermost rib in the axial direction of a tyre, and in a central part 25a in an axial direction of the rib 25B away from the main groove 24. In the shallow cut 27, a projection length W27 in the axial direction of a tyre is set to 10-70% of a rib width W25B, a depth to 30-100% of the depth of the outermost main groove 24A, an angle with an axial direction to approximate 15 deg., and a circumferential interval to 3-20mm. This constitution enables prevention of the occurrence of deviated wear.