Reinforced tire curing bladder

• US 5,062,781 A
• Filed: 08/07/1989
• Issued: 11/05/1991
• Est. Priority Date: 08/10/1988
• Status: Expired due to Term

• Current Assignee: Pirelli Tyre SPA (Pirelli & C SPA)
• Original Assignee: Firelli Armstrong Tire Corporation
• Inventors: Valaitis, Joseph W., Szyms, Walter
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Maki, Steven D.
• Application Number:
  US07/390,627
• Time in Patent Office: 820 Days
• Field of Search: 156/120, 156/121, 156/123, 156/133, 156/172, 156/416, 156/117, 156/178, 264/315, 264/326, 264/501, 249/65, 249/179, 425/42, 425/43, 425/44, 425/45, 425/52, 425/53, 425/389, 425/390, 425/DIG. 14, 425/33, 425/812, 425/38, 92/93, 92/103 F
• US Class Current: 425/52
• 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: B29C 53/56 Winding and joining, e.g. winding spirally winding in general B65H
• 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: Y10S 425/812 Venting

Abstract

A thin, membrane-like cylindrical rubber tire curing bladder is provided with reinforcing cords wound in parallel spiral paths at any composite angle to the longitudinal axis of the cylinder. When installed on the centerpost mechanism of a tire curing press and inflated in the curing process, the bladder length increases due to partial and reversible straightening of the spirally wound cord reinforcement. This permits optimum fit of the bladder in the tire being processed with uniform controlled growth of the membrane providing improved cured tire uniformity. Longer service life of the bladder is thereby achieved. The bladder is a good heat conductor inherent to its thin matrix, unlike previously known bladders. The bladder of the present invention also provides for a unique venting mechanism during the curing process to provide a tire having reduced potential for trapped air related anomalies.

Claims

1. A tire processing bladder comprising a hollow, tubular relatively thin member having a tubular circumference extending around a tubular axis, said tubular membrane member inflatable to provide a circular circumference greater than the tubular circumference, said tubular membrane member having included therein a plurality of parallel cords, each said cord traversing a spiral path from one end to an opposing end of said tubular membrane at an angle of inclination with respect to the tubular axis, the relative thinness of said tubular membrane member permitting said cords to protrude from said tubular membrane member when formed to have said circular circumference to create reciprocal shallow areas between said cord lengths and thus form a matrix for venting air trapped between said tubular membrane member and an uncured tire, the inclination angle of said cords limiting the circular circumference by limiting the amount said tubular membrane member may be inflated, said tubular membrane member rotating substantially in a screw manner upon inflation into relatively close engagement with an inside surface of said uncured tire.

2. The bladder of claim 1 wherein each said cord is spaced uniformly from every other adjacent cord around the tubular circumference.

3. The bladder of claim 2 wherein each said cord extends continuously from the one end to the opposing end of said tubular membrane member.

4. The bladder of claim 3 wherein said cords tend towards parallel alignment with said axis as said tubular membrane member is inflated.

5. The bladder of claim 3 comprising a pair of means for enclosing said opposing ends to form a relatively fluid impervious chamber for receiving a fluid under pressure, each said enclosing means operatively coupled to said cords at respective ends of said tubular membrane member, at least one of said enclosing means is rotatable about said axis upon inflation of said tubular membrane member.

6. The bladder of claim 5 wherein at least one of said enclosing means is movable along said axis toward the other, and wherein said tubular membrane member balloons upon inflation and as said enclosing means are so moved towards each other into a generally toroidal shape.

7. A tire processing bladder responsive to the introduction of fluid thereto under a range of fluid pressures for assuming a relatively uninflated state for insertion into a tire processing assembly and a relatively inflated state during tire processing carried out in said assembly, said bladder comprising a tubular shaped membrane of rubber formed along a tubular axis and having embedded therein a plurality of reinforcing cords traversing substantially parallel paths within said rubber in a generally spiral pattern about said tubular axis, and which cords as said bladder is inflated from said relatively uninflated towards said relatively inflated state by said introduction of fluid tend to become aligned away from said spiral pattern and more towards a longitudinal direction aligned with said tubular axis, said bladder forming a substantially toroid-shaped portion inside a tire being cured in said relatively inflated state inside said tire processing assembly, said substantially toroid-shaped portion tending to rotate into relatively close engagement with an inside surface of said tire being cured in response to said introduction of fluid, said cords protruding from said bladder when formed to have said substantially toroid-shaped portion to create reciprocal shallow areas between said cords and thus form a matrix for venting air trapped between said bladder and an uncured tire.

8. An improved tire bladder of claim 7, wherein the average thickness of said bladder is of the order of about 0.075 to about 0.40 inches.

9. An improved tire bladder of claim 7, wherein said reinforcing material comprises aramid cord.

11. An improved tire bladder according to claim 7 wherein said rubber is butyl rubber.

10. An improved tire bladder of claim 12, wherein said aramid cord has a denier in the range of about 400 to about 3500.