Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2000-02-14
2001-12-18
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S040700, C073S049000
Reexamination Certificate
active
06330821
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for inspecting for evidence of leakage of an expansion vessel, and more particularly, to a method for inspecting for evidence of a pinhole leak in an expansion vessel.
BACKGROUND ART
Many curing devices for molded products use an expansion vessel, also known as a curing bladder. In a curing device, most expansion vessels are pressurized with a fluid heat source, such as steam. The fluid heat source causes the expansion vessel to expand, pushing the product tightly against the mold. Further, the heat from the fluid heat source helps to at least partially cure the molded product.
Problems occur when a defect, such as a pinhole leak, forms in the expansion vessel. In the tire industry, pinhole leaks in expansion vessels on curing devices are one of the industry's largest causes of tire scrap. Pinhole leaks hi expansion vessels cost tire manufacturers millions of dollars per year. A pinhole leak allows high temperature steam to contact the innerliner of the tire. One possible result from this contact is an undercured area in the innerliner. Another possible result is the permeation of steam into the ply area of the tire causing a blister that can result in the separation of the plies. Currently, the first inspection of a tire for the effects of pinhole leaks occurs in the final finish area of the tire plant, minutes after the tire leaves the curing device. If a tire in final finish is found to be defective as a result of a pinhole leak, then up to ten additional tires may have been cured with the same defective expansion vessel prior to discovery of the problem. Generally, all of these tires must be scrapped.
In order to reduce scrap caused by defective expansion vessels, the expansion vessels are changed after a set number of cycles. However, this preventative measure does not always prevent scrap because a pinhole leak may develop prior to this set number of cycles. Additionally, this preventive measure may change out some expansion vessels that still have many more cycles in their effective life. Thus, scrap tires may still result, money is lost by not utilizing the full life of the expansion vessel, and additional labor (costs arise due to more frequent expansion vessel changes.
Curing device manufacturers have attempted to limit scrap products caused by pinhole leaks in expansion vessels by incorporating a monitoring system into the curing device. Before a product to be cured is placed into the curing device, the expansion vessel of the curing device is pressurized. The pressurized expansion vessel is isolated by closing the valves in the supply and discharge lines. The monitoring system monitors the pressure in the expansion vessel to determine if a leak is present
U.S. Pat. No. 5,417,900 entitled “VACUUM LEAK DETECTOR FOR A TIRE CURING PRESS” discloses a device and a method for detecting a leak in an inflatable elastomeric bladder of a curing press. The spent curing fluid is pumped through an exhaust line in which a venturi ejector is located. The venturi ejector causes a vacuum to be created as the fluid is being removed. A vacuum sensor monitors this vacuum. If a predetermined vacuum strength is not reached in a predetermined time, a leak is assumed to exist.
These prior art systems work well when a leak occurs at the coupling attaching the expansion vessel to the curing device. However, these systems are not adequate for detecting a pinhole leak in an expansion vessel. Since the quantity of fluid lost through a pinhole leak is small, relative to a coupling leak, determining the presence of such a leak using pressure and/or vacuum sensors is very difficult. These devices are also ineffective because they can also signal leaks in bladder seals, thus producing false positive responses.
SUMMARY OF THE INVENTION
This invention provides a method for detecting leakage of an expansion vessel that, in an inflated form, occupies or has occupied at least a portion of a cavity of an elastomeric article. The method includes the step of: adding a tracer gas to a pressurized fluid The pressurized fluid is used to inflate the expansion vessel. The tracer gas is added prior to the expansion vessel's withdrawal from the cavity of the elastomeric article.
The method is characterized by the step of examining the atmosphere within the cavity of the elastomeric article, and not within the expansion vessel, for evidence indicating that a portion of the tracer gas has escaped from the expansion vessel.
DEFINITIONS
For ease of understanding this disclosure, the following terms are defined.
“Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards, and chafers, to fit a design rim. The beads are associated with holding the tire to the wheel rim.
“Curing” means the process of heating or otherwise treating a rubber or plastic compound to convert it from a thermoplastic or fluid material into a solid, relatively heat-resistant state by causing cross-linking of the compound. When heating is employed, the process is called vulcanization.
“Elastomer” means a resilient material capable of recovering size and shape after deformation.
“Elastomeric article” is an article that is at least partially made from an elastomer.
“Innerliner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.
“Pneumatic tire” means a laminated Mechanical device of generally toroidal shape, usually an open torus, having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire, through its tread, provides traction and contains the fluid that sustains the vehicle load.
“Radial” and “radially” are used to mean directions toward or away from the axis of rotation of the tire.
REFERENCES:
patent: 3175390 (1965-03-01), McConkie
patent: 3721117 (1973-03-01), Ford et al.
patent: 3942922 (1976-03-01), Cole et al.
patent: 4188818 (1980-02-01), Garrison
patent: 4221124 (1980-09-01), Jones
patent: 4754638 (1988-07-01), Brayman et al.
patent: 4785666 (1988-11-01), Bergquist
patent: 4791805 (1988-12-01), Gates
patent: 4862731 (1989-09-01), Gates
patent: 4893497 (1990-01-01), Danielson
patent: 4920785 (1990-05-01), Etess
patent: 5172583 (1992-12-01), Tallon
patent: 5417900 (1995-05-01), Martin, Sr.
patent: 5618991 (1997-04-01), Levinrad
Arnold William Allen
Incavo Joseph Alan
The Goodyear Tire & Rubber Company
Wheeler David E
Wiggins David J.
Williams Hezron
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