Open-end bladder for vulcanization of pneumatic tire

• US 4,776,781 A
• Filed: 10/06/1987
• Issued: 10/11/1988
• Est. Priority Date: 10/06/1987
• Status: Expired due to Term

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Sakai, Nobuhiro
• Primary Examiner(s): Nozick, Bernard
• Application Number:
  US07/105,060
• Time in Patent Office: 371 Days
• Field of Search: 425/35, 425/36, 425/48, 425/49, 425/51, 425/52, 425/58, 425/53
• US Class Current: 425/48
• CPC Class Codes: B29C 43/104 the mould cavity lying totally outside the axis of symmetry, e.g. toroidal moulds
• CPC Class Codes: B29C 43/3642 Bags, bleeder sheets or cauls for isostatic pressing
• CPC Class Codes: B29D 2030/0655 Constructional or chemical features of the flexible cores
• CPC Class Codes: B29D 30/0654 Flexible cores therefor, e.g. bladders, bags, membranes, diaphragms elastic cores or mandrels for shaping of plastics B29C33/505; bags for isostatic pressing in compression moulding B29C43/12, B29C43/3642
• CPC Class Codes: B29D 30/0662 Accessories, details or auxiliary operations
• CPC Class Codes: B29L 2022/025 Bladders

Abstract

An open-end bladder for vulcanizing a pneumatic tire. The bladder has an annular form and a pair of opening extending through the bladder in the axial direction of the bladder. A pressure fluid is introduced into the bladder to bring it into pressure contact with the still unvulcanized tire to preshape it and to support the tire on the inside surface of the tire at the same time of the vulcanization. The bladder comprises corners extending outward from both metal-clamped end portions having the openings, first oblique portions curved and extending outward from the corners, second oblique portions extending outward from the first oblique portions, and a convex portion curved and extending outward from the second oblique portions to the maximum-diameter cross section of the bladder to couple the upper and lower halves of the bladder to each other. The thickness of the bladder is gradually decreased from the portions of the bladder, which correspond to the beads of the still unvulcanized tire, to the portion of the bladder, which corresponds to the tread of the still unvulcanized tire.

Claims

1. An open-end bladder for vulcanizing a pneumatic tire, which has an annular form and a pair of openings extending through said bladder in the axial direction thereof and into which a pressure fluid is introduced to bring said bladder into pressure contact with the still unvulcanized tire to preshape said tire and to support said tire on the inside surface thereof at the time of said vulcanization, characterized in that said bladder comprises corners extending outward from both metal-clamped end portions having said openings, first oblique portions curved and extending outward from said corners, second oblique portions extending outward from said first oblique portions, and a convex portion curved and extending outward from said second oblique portions to the maximum-diameter cross section of said bladder to couple the upper and lower halves of said bladder to each other;

and the thickness of said bladder is gradually decreased from the portions of said bladder, which correspond to the beads of said still unvulcanized tire, to the portion of said bladder, which corresponds to the tread of said still unvulcanized tire.

2. An open-end bladder according to the claim 1, in which the center of curvature of a curved portion which is the joint of the corner and the first oblique portion is located inside said bladder;

the center of curvature of a curved portion which is the joint of said first oblique portion and the second oblique portion is located outside said bladder; and

the center of curvature of the convex portion curved and extending outward from the second oblique portions and constituting the maximum-diameter portion of said bladder is located inside said bladder.