Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2001-03-02
2003-04-08
Staicovici, Stefan (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S275000, C264S328100, C425S110000, C425S472000
Reexamination Certificate
active
06544460
ABSTRACT:
TECHNICAL FIELD
This invention relates to a fixture for disposing a material on an airfoil or in an airfoil for an axial flow rotary machine. The material is heated to liquefy the material and the material is flowed to passages in the airfoil where the material solidifies to block, for example, a coating from entering the passage or a laser beam from striking the interior of the passage as a cooling air hole is drilled through to the passage. The material is commonly referred to as “filler material” or “blocking material” and is disposed on the interior or exterior of the airfoil. More particularly, this invention relates to a fixture for disposing filler material in passages in the airfoil, such as passages in a rotor blade or a stator vane, which are the relatively large supply passages or the relatively small passages which provide conduits from the supply passage to the interior or exterior of the airfoil. Although this invention was developed in the field of axial flow rotary machines, this invention has application to other fields where a material is heated to liquefy the material and is flowed thereafter to the article where the material is disposed on or in the article.
BACKGROUND OF THE INVENTION
Airfoils for gas turbine engines are disposed in a flow path for working medium gases. Examples of such airfoils are turbine blades and turbine vanes. The airfoils are bathed in hot gases as the gases are flowed through the engine. Cooling air is flowed though main supply passages on the interior of the airfoil under operative conditions. Stator vanes are typically larger than rotor blades and the main supply passages for cooling air in a turbine vane are larger in volume than the supply passages in a rotor blade.
The cooling air is then flowed from these passages through the airfoil to keep the temperature of the airfoil within acceptable limits. Cooling air holes also extend from the interior to the exterior of the airfoil. These cooling air holes are typically called “film cooling holes.” The cooling air holes are small and may have diameters that are in a range of eleven to seventeen mils (0.011-0.017 inches). Cooling air is flowed from the passages on the interior of the airfoil through the cooling air holes the hot walls to the exterior surface of the airfoil. The cooling air provides transpiration cooling as the air passes through the wall and, after the air is discharged from the airfoil, provides film cooling with a film of air on the exterior. The film of cooling air provides a barrier between the airfoil and the hot, working medium gasses.
The holes are drilled in predetermined patterns and are contoured to ensure adequate cooling of the airfoil. One way to drill the holes uses a laser to direct a beam of coherent energy at the exterior of the airfoil. The intense radiation from the laser beam bums through the wall of the airfoil, leaving behind a hole which provides a satisfactory conduit for cooling air. As the laser beam penetrates through the airfoil wall into an interior cavity, the laser beam may strike adjacent structure on the other side of the cavity causing unacceptable damage to the airfoil. Accordingly, blocking material may be disposed in the cavity to block the laser beam from striking walls bounding the cavity after the beam penetrates through the airfoil wall.
One approach is to leave disposed within the airfoil the ceramic casting core around which the blade is poured during the manufacturing process. The ceramic core provides a suitable blocking material. The ceramic core is subsequently removed by well known leaching techniques. This approach is described in U.S. Pat. No. 5,222,617 entitled “Drilling Turbine Blades” issued to Gregore, Griffith and Stroud.
Another example of a filler material used for blocking material is wax or a wax-like material. The material is melted so that it may easily flow into interior passages, such as the leading edge passage of the airfoil. The temperature of the molten material when heated above its melting point may exceed two hundred and fifty degrees Fahrenheit (250°). The molten material may be poured by hand or injected into the cavity or may even be sprayed or painted on the surface to be protected. However, the molten material may severely scald personnel working with the material. Moreover, the operation is time consuming if such material is poured by hand into the airfoil.
One example of a wax-like blocking material which uses an additive to avoid forming voids is discussed in U.S. Pat. No. 5,049,722, issued to Corfe and Stroud, entitled “Laser Barrier Material And Method Of Laser Drilling.” In Corfe, a PTFE (polytetrafluoroethylene) wax-like material is disposed in a wax base. The PTFE helps avoid the formation of voids.
Still another approach is to use a masking agent, such as an epoxy resin, which is disposed in the airfoil in a fluid state. The epoxy resin is disposed in the airfoil by simply pouring the resin into the airfoil. The epoxy resin is at room temperature and poses no scalding hazard to personnel. The epoxy resin is further processed to harden the fluid and cause it to become a more solid material similar to the PTFE wax mentioned in U.S. Pat. No. 5,049,722. However, the resin is relatively viscous compared to molten wax and has difficulty in flowing through small connecting passages on the interior of the airfoil.
Another approach is to use a thixotropic medium that includes material for dispersing laser light. This approach is discussed in U.S. Pat. No. 4,873,414 issued to Ma and Pinder entitled “Laser Drilling of Components”. A particular advantage of this medium is that the dispersant material emits light when contacted by the laser light. Monitoring the light provides a method of detecting the presence of the laser beam as the laser beam breaks through the surface of the article and controlling the beam by using a feedback control to determine whether or not the laser beam has drilled a through hole. In addition, the viscosity of the medium is decreased by forcing the medium through a nozzle for lowering the viscosity of the medium so that the medium flows readily over an inner surface of the component.
Another approach is shown in U.S. Pat. No. 5,140,127 entitled “Laser Barrier Material” issued to Stroud and Corse. This approach uses an injectable barrier material which is a composition selected from the group consisting of a first copolymer of tetrafluoroethylene and hexfluoropropylene and a second copolymer having a polytetrafluoroethylene backbone and a least one fluorinated alkoxy side group. The material is poured or injected into the interior of the component.
Another approach is shown in U.S. Pat. No. 5,767,482 entitled “Laser Barrier Material and Method” issued to Turner. Turner uses finely divided crystalline material such as sodium chloride (salt), or other metal salts which are thermally stable and possess a high melting point. Salt may be introduced into the interior of a component by pouring or by making it a paste with water and injecting it. The salt is removed by washing the component with water.
The above art notwithstanding, scientists and engineers working under the direction of Applicants Assignee have sought to develop materials, methods, and devices for disposing a filler material in or on an article, such as for blocking a laser beam on the interior of airfoils which are useable for mass production operations and that provide for relatively easy removal from the article without performing several time consuming operations.
SUMMARY OF INVENTION
This invention is in part predicated on the recognition that fixtures used with polymer filler material that is heated to liquefy the material in mass production operations may provide significant production advantages by reducing the time needed to fill articles. The term “heated” refers to raising the temperature of the material whether by the transfer of heat or by doing work on the material, such as forcing the material through a nozzle. These fixtures may be used, for example, for filling the interiors of airfoils for g
Boucher Kenneth M.
Funk Stanley J.
Reed Gordon M.
Fleischhauer Gene D.
Staicovici Stefan
United Technologies Corporation
LandOfFree
Method and fixture for disposing filler material in an article does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and fixture for disposing filler material in an article, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and fixture for disposing filler material in an article will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3095533