Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – Presses or press platen structures – per se
Reexamination Certificate
1999-04-23
2001-12-25
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
Presses or press platen structures, per se
C156S581000, C156S094000, C029S023510
Reexamination Certificate
active
06332490
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to repair of a strip of material bonded to an article surface, and more particularly, in one form, to the repair of a strip of wear resistant material bonded to the surface of a gas turbine engine blade.
The manufacture of gas turbine engine blades includes manufacture of composite blades incorporating fibrous or filament type materials, typically including a matrix and a reinforcing material. Cooler operating blades in such an engine include fan or compressor blades frequently made of stacked or laid-up plies of a reinforced polymeric material. Such blades are described in a variety of publications including U.S. Pat. No. 3,883,267—Baudier et al., patented May 13, 1975; and U.S. Pat. No. 5,573,377—Bond et al., patented Nov. 12, 1996.
The surface of certain composite blades is relatively soft compared with a metal surface with which it might interact. Therefore, it has been a practice to bond a wear resistant material to a composite blade surface which is subject to a rubbing or fretting type wear as a result of contact with a cooperating member during engine operation. One form of wear resistant material used in a gas turbine engine is a low friction wear coat on the dovetail of a composite blade as shown at
38
in
FIGS. 4 and 5
of the above identified Bond et al. patent. Another type of such a wear resistant material is in the form of a strip of material, such as pre-impregnated glass and Teflon fiber hybrid cloth, bonded with an adhesive to composite blade surfaces as the dovetail, airfoil, etc. Such a wear strip has various edges which can be damaged, including a lengthwise edge, end edges, the edge of a corner at the juncture of a lengthwise edge and an end edge, etc. Such damage can result from operation, mishandling, etc., which has caused fraying or loosening of fibers of the strip, or disbonding of the adhesive bonding the wear strip to the blade surface.
A current practice specifies complete removal of a damaged wear strip and its adhesive, followed by replacement of the strip using a curing cycle at about 300° F. and the application of pressure, for example in an autoclave. Removal of the entire wear strip and complete replacement by processing at such a temperature and pressure is time consuming and requires use of relatively costly apparatus, adding to the cost of repair. However, frequently damage to the wear strip is in a relatively small area and is localized, for example a discrete disbanding or fraying of a portion along a lengthwise edge of the wear strip.
BRIEF SUMMARY OF THE INVENTION
The present invention, in one form, provides a method for repairing a discrete damaged part of a strip bonded to an article surface, including applying a first removable masking member to the article surface along and adjacent to the discrete damaged part of the strip and separated from an edge of the strip connected with the damaged part by a gap of at least 0.005″; and applying a second removable masking member to an outer surface of the strip at least over the discrete damaged part and portions bordering the discrete damaged part. A repair adhesive, which can be cured at a curing temperature less than a higher temperature which can result in damage to properties of the article, is applied to the discrete damaged part at the edge of the strip, beneath the second masking member and the wear strip. The repair adhesive is cured at the curing temperature and the first and second masking members are removed.
In another form, the present invention provides apparatus for use in bonding the strip to an article surface at an end portion of an article, the end portion including an article first surface having a first surface profile, and an article second surface spaced apart from the article first surface and having a second surface profile. The article first and second surfaces are disposed with respect one to the other at a relative spatial position. The apparatus comprises a body having there through a body channel to receive the end portion of the article. The channel is defined by a plurality of inwardly facing body surfaces which include first and second support surfaces spaced apart and positioned relative one to the other substantially to coincide with the relative spatial position respectively of the article first and second surfaces. The first support surface is shaped substantially to reproduce the first surface profile and to receive and register with the article first surface; and the second support surface is shaped substantially to reproduce the second surface profile and to receive and register with the article second surface.
REFERENCES:
patent: 819259 (1906-05-01), White
patent: 2108077 (1938-02-01), Robinson
patent: 4254946 (1981-03-01), Kerr et al.
patent: 4659525 (1987-04-01), Speer
patent: 5156383 (1992-10-01), Williams
patent: 5573377 (1996-11-01), Bond et al.
patent: 5814174 (1998-09-01), Fong
patent: 5863035 (1999-01-01), Howell
Ball Michael W.
General Electric Company
Hess Andrew C.
Narciso David L.
Piazza Gladys
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