Leak Detection in Vacuum Bags
AssigneeThe Boeing Company
InventorsFinley B. Miller, Michael E. Benne
Life of this patent
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Abstract
Air leaks in a vacuum bag are detected using a leak detection film covering the inside face of the bag. The film includes a gas permeable binder carrying oxygen sensitive material that changes in physical appearance at the location of an air leak. The film may be adhered to the inside face of the bag or may form a separate membrane that is placed over a layup being molded in the bag. The film may be illuminated with light having a wavelength selected to cause the film to luminesce.
Claims71
A device for indicating the location of an air leak in a vacuum bag used in processing parts, comprising:
- a film including oxygen sensitive material inside of and extending across the vacuum bag, the oxygen sensitive material changing in physical appearance at the general location of an air leak in the vacuum bag.
A vacuum bag assembly used in bonding parts together, comprising:
- a vacuum bag covering at least one of the parts and defining a space in which a vacuum may be drawn to assist in bonding the parts;
- and
- a leak detection film inside of and extending across the vacuum bag, the leak detection film including oxygen sensitive material that changes in physical appearance at the general location of an air leak in the vacuum bag.
A device for detecting an air leak in a vacuum bag used in fabricating composite parts, comprising:
- a film inside of and substantially coextensive with the area of the bag subjected to a vacuum, the film including an oxygen permeable binder and an oxygen sensitive material held in the binder, the oxygen sensitive material having at least one visual characteristic that changes in the presence of oxygen introduced into the vacuum bag by the air leak.
A vacuum molding bag, comprising:
- a flexible, substantially transparent polymer sheet having an inside face and an outside face;
- and
- a film on the inside face of the polymer sheet, the film including an oxygen permeable binder and an oxygen sensitive material held in the binder, the oxygen sensitive material exhibiting a change in physical appearance in the area of an air leak in the vacuum molding bag to indicate the location of the air leak.
A device for detecting gas leaks in a gas impermeable, transparent membrane for use in manufacturing and industrial processes, comprising:
- a film extending across the membrane for providing a visual indication of the location of a gas leak in the membrane.
A device for detecting gas leaks in a seal beneath a transparent vacuum bag, comprising:
- a film inside of the vacuum bag and disposed adjacent the seal, the film including a gas permeable binder and a gas sensitive material held in the binder, the gas sensitive material having at least one visual characteristic that changes in the presence of gas entering the vacuum bag through a leak in the seal.
A method of fabricating a vacuum process bag allowing detection of air leaks in the bag, comprising the steps of:
- forming a flexible polymer sheet;
- and,
- applying a leak detection film on one face of the flexible polymer sheet.
The method of claim 64, wherein step of applying the leak detection film on the one face of the flexible polymer sheet is performed by painting the leak detection film on the one face of the flexible polymer sheet.
The method of claim 64 further comprising the step of:
- fabricating the leak detection film by extruding an oxygen permeable binder.
The method of claim 64, wherein steps of forming the flexible polymer sheet and applying the leak detection film on the one face of the flexible polymer sheet are performed substantially simultaneously by co-extruding the flexible polymer sheet and the leak detection film.
The method of claim 64, wherein step of applying the leak detection film on the one face of the flexible polymer sheet is performed by bonding the leak detection film to the one face of the flexible polymer sheet.
The method of claim 64 further comprising the step of:
- fabricating the leak detection film by compounding an oxygen permeable binder and an oxygen sensitive material that changes in appearance when subjected to oxygen.
A vacuum process bag used to produce parts for vehicles fabricated by a process comprising:
- forming a flexible polymer sheet;
- and,
- applying a leak detection film on one face of the polymer sheet.
A vacuum process bag used to produce aircraft subassemblies fabricated by a process comprising:
- forming a flexible polymer sheet;
- and,
- applying a leak detection film on one face of the polymer sheet.
A method of infusing a preform with resin, comprising the steps of:
- forming redundant vacuum chambers about the perform such that—
- an inner vacuum chamber is disposed within an outer vacuum chamber;
- and
- if one of the vacuum chambers fails, the other vacuum chamber maintains vacuum integrity;
- evacuating the vacuum chambers such that the outer vacuum chamber has a pressure approximately equal to or greater than a pressure in the inner vacuum chamber;
- placing a leak detection film inside at least one of the inner and outer vacuum chambers;
- infusing resin into the preform while substantially maintaining the pressures in the vacuum chambers;
- and,
- detecting a leak in the at least one vacuum chamber by observing changes in the visual appearance of the leak detection film at the location of the leak.
Dependencies are inferred from the claim text.