Mold pin, tire mold and tire manufacturing method

• US 9,724,885 B2
• Filed: 08/14/2013
• Issued: 08/08/2017
• Est. Priority Date: 10/11/2012
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Abe, Shotaro
• Primary Examiner(s): Sultana, Nahida
• Application Number:
  US13/966,552
• Publication Number:
  US 20140103577A1
• Time in Patent Office: 1,455 Days
• Field of Search: 264326, 425 281
• CPC Class Codes: B29D 2030/0612 Means for forming recesses or protrusions in the tyres, e.g. grooves or ribs, to create the tread or sidewalls patterns
• CPC Class Codes: B29D 30/0606 Vulcanising moulds not integral with vulcanising presses for solid tyres B29D30/02
• CPC Class Codes: B29D 30/0662 Accessories, details or auxiliary operations
• CPC Class Codes: B29D 30/66 Moulding treads on to tyre casings, e.g. non-skid treads with spikes

Abstract

A mold pin fixed to a tread mold for a tire tread and forming a stud hole is disclosed. The mold pin is provided at one end of its main shaft portion with an expanded portion having a larger outer diameter. The expanded portion comprises a supporting part formed integrally with the main shaft portion, and an outer-shell part disposed on the outer surface of the supporting part to define the maximum outer diameter of the expanded portion. When a force directed from the main shaft portion toward the expanded portion is applied to the outer-shell part, the outer-shell part is moved so as to reduce the maximum outer diameter.

Claims

1. A mold pin used by being fixed to a tread mold for molding a tread of a vehicle tire to form a stud hole in the tread, comprising

a main shaft portion to be fixed at its one end to the tread mold so as to protrude from a tread molding surface of the tread mold, and

an expanded portion disposed at the other end of the main shaft portion and having an outer diameter more than the outer diameter of the main shaft portion,

wherein

the expanded portion comprises a supporting part formed integrally with the main shaft portion, and an a outer-shell part disposed on the outer surface of the supporting part to define the maximum outer diameter of the expanded portion,

the outer-shell part is movably supported by the supporting part such that when a force directed from said one end toward said other end of the main shaft portion is applied to the outer-shell part, the outer-shell part is moved so as to reduce the maximum outer diameter, and

the outer-shell part is made up of a plurality of sector shells, and a radially inside end of each sector shell is connected to the supporting part in a cantilever manner by the use of a connector made of a heat-resistant, flexible and deformable resin.

2. The mold pin according to claim 1, wherein

the supporting part is bulb-shaped,

the outer-shell part closely contacts with the outer surface of the supporting part, and

the volumetric thermal expansion coefficient P1 of the supporting part is the same as or more than the volumetric thermal expansion coefficient P2 of the outer-shell part.

3. The mold pin according to claim 2, wherein

the ratio P1/P2 of the volumetric thermal expansion coefficient P1 of the supporting part and the volumetric thermal expansion coefficient P2 of the outer-shell part is not less than 1.000 and not more than 1.015.

4. The mold pin according claim 1, wherein

the ratio D2/D1 of the maximum outer diameter D2 of the expanded portion to the outer diameter D1 of the main shaft portion is not less than 1.2 and not more than 3.0.

5. The mold pin according to claim 1,

wherein

the maximum outer diameter of the supporting part is more than the outer diameter of the main shaft portion, and

when each of the sector shells is subjected to a force directed from said one end toward said the other end, a radially outside end of said sector shell is movable about the connector as a point of support to a position inside a cylinder circumscribed with the maximum outer diameter position of the supporting part.

7. The mold pin according claim 2, wherein

the ratio D2/D1 of the maximum outer diameter D2 of the expanded portion to the outer diameter D1 of the main shaft portion is not less than 1.2 and not more than 3.0.

8. The mold pin according claim 3, wherein

the ratio D2/D1 of the maximum outer diameter D2 of the expanded portion to the outer diameter D1 of the main shaft portion is not less than 1.2 and not more than 3.0.

6. A tire mold comprising a tread mold provided with a plurality of the mold pins used by being fixed to said tread mold for molding a tread of a vehicle tire to form a stud hole in the tread, each of said mold pins comprising

a main shaft portion to be fixed at its one end to the tread mold so as to protrude from a tread molding surface of the tread mold, and

an expanded portion disposed at the other end of the main shaft portion and having an outer diameter more than the outer diameter of the main shaft portion,

wherein

the expanded portion comprises a supporting part formed integrally with the main shaft portion, and an a outer-shell part disposed on the outer surface of the supporting part to define the maximum outer diameter of the expanded portion,

the outer-shell part is movably supported by the supporting part such that when a force directed from said one end toward said other end of the main shaft portion is applied to the outer-shell part, the outer-shell part is moved so as to reduce the maximum outer diameter, and

the outer-shell part is made up of a plurality of sector shells, and a radially inside end of each sector shell is connected to the supporting part in a cantilever manner by the use of a connector made of a heat-resistant, flexible and deformable resin.

9. The tire mold as set forth in claim 6, wherein the supporting part of the mold pin is bulb-shaped, the outer-shell part of the mold pin closely contacts with the outer surface of the supporting part, and the volumetric thermal expansion coefficient P1 of said supporting part is the same as or more than the volumetric thermal expansion coefficient P2 of said outer-shell part.

10. The tire mold as set forth in claim 9, wherein the ratio P1/P2 of the volumetric thermal expansion coefficient P1 of the supporting part of the mold pin and the volumetric thermal expansion coefficient P2 of the outer-shell part of the mold pin is not less than 1.000 and not more than 1.015.

11. The tire mold as set forth in claim 6, wherein the ratio D2/D1 of the maximum outer diameter D2 of the expanded portion to the outer diameter D1 of the main shaft portion is not less than 1.2 and not more than 3.0.

12. The tire mold as set forth in claim 6,

wherein

the maximum outer diameter of the supporting part is more than the outer diameter of the main shaft portion, and

when each of the sector shells is subjected to a force directed from said one end toward said the other end, a radially outside end of said sector shell is movable about the connector as a point of support to a position inside a cylinder circumscribed with the maximum outer diameter position of the supporting part.