Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-04-26
2003-01-28
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S297000, C428S172000, C244S119000
Reexamination Certificate
active
06511570
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a body structure composed of a stiffened panel of a fiber-reinforced composite, and a body structure produced by the method.
Fiber-reinforced composites (prepregs) are light in weight and high in strength to have been widely used for automobiles, ships, aircrafts, etc. Although most of conventional aircrafts made of the fiber-reinforced composites have a body structure composed of honeycomb sandwich panels, the body structure is preferably composed of integrally formed, stiffened panels to obtain a lighter aircraft with improved reliability. The stiffened panel, in particular, such that a skin and stiffeners are integrally formed, is the most suitable for production of lightened body structure.
FIG. 1
is a partial, schematic perspective view showing an example of the body structure composed of the stiffened panel. The body structure
1
shown in
FIG. 1
comprises a skin
2
, shorter stringers
3
placed in lengthening direction, and taller frames
4
placed in circumferential direction. The stringers
3
and the frames
4
are simply shown in a quadrangular prism shape, they often having a section of C-shape, I-shape, J-shape, T-shape, etc. in practical. Such a body structure is generally produced by the steps of: placing a skin member and stiffener members (preformed stringer members and preformed frame members) made of a fiber-reinforced composite on a forming tool; and adhesive-forming them by heating under a pressure using a pressure bag, etc.
Intersections of the preformed stringer members and the preformed frame members are appropriately worked. As shown in
FIG. 2
, a body structure for a large aircraft is generally obtained by providing an open hole
51
in a preformed frame member
41
, and by making a preformed stringer member
31
pass through the open hole
51
on a skin member
21
. However, providing such an open hole increases production cost of the body structure. Particularly, in the case of a body structure for a small aircraft, height of the preformed frame member is approximately 50 mm to secure a desired interior space in contrast with the large aircraft having a frame height of approximately 100 mm, so that it is difficult to provide the open hole in the preformed frame member, thereby increasing the production cost.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for steadily producing a body structure composed of a stiffened panel of a fiber-reinforced composite with superior quality and reduced production cost, and a body structure produced thereby.
As a result of intensive research in view of the above object, the inventor has found that a body structure of superior quality can be produced with reduced production cost if a frame member is divided into an outer frame member and an inner frame member, the outer frame member being integrally formed with a skin member and a stringer member to prepare an assembly, and the inner frame member being adhesive-formed with the assembly. The present invention has been accomplished by the finding.
Thus, in a method for producing a body structure of a fiber-reinforced composite according to the present invention, a skin member, a plurality of preformed stringer members, a plurality of preformed outer frame members and an inner frame member each made of a fiber-reinforced composite are used, and (a) the skin member is placed on a forming tool, (b) the preformed stringer members are arranged on the skin member at predetermined intervals, (c) the preformed outer frame members are arranged on the skin member to intersect the preformed stringer members, (d) the skin member, the preformed stringer members and the preformed outer frame members are integrally hardened by heating under a pressure to prepare an assembly having a skin, stringers and an outer frame, (e) the inner frame member hardened by heating under a pressure beforehand is put into contact with the outer frame, and (f) the inner frame member and the assembly are adhesive-formed by heating under a pressure.
In the method of the present invention, the preformed stringer members pass through spaces between the preformed outer frame members and the inner frame member, so that there is no need to provide the above-described open hole. Further, dimensional error of the preformed outer frame members and the inner frame member can be absorbed when they are adhesive-formed, whereby a body structure excellent in dimensional accuracy can be produced with high reliability.
The preformed outer frame members preferably have a T-shaped section, and the inner frame member preferably has an L-shaped section. The L-shaped inner frame member can be formed and placed easier than a member of C-shape, J-shape, etc., thereby reducing production cost and steadying quality of the body structure. Further, it is preferred that the inner frame member is a seamless ring in shape from the viewpoint of strength of the body structure.
The inner frame member is preferably hardened by heating at 120 to 250° C. under a pressure beforehand, the skin member, the preformed stringer members and the preformed outer frame members are preferably integrally hardened by heating at 120 to 250° C. under a pressure, and the inner frame member and the assembly are preferably adhesive-formed by heating at 120 to 180° C. under a pressure.
A body structure of the present invention can be produced by the method according to the present invention mentioned above.
REFERENCES:
patent: 5242523 (1993-09-01), Willden et al.
patent: 5451377 (1995-09-01), Asher et al.
patent: 5622733 (1997-04-01), Asher et al.
patent: 5746553 (1998-05-01), Engwall
patent: 5876546 (1999-03-01), Cloud
patent: 6364250 (2002-04-01), Brink et al.
patent: 0 650 825 (1995-05-01), None
Patent Abstracts of Japan, JP 05 008316, Jan. 19, 1993.
European Search Report for EP 01 30 3876.
Honda Giken Kogyo Kabushiki Kaisha
Sells James
LandOfFree
Method for producing body structure of fiber-reinforced... 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 for producing body structure of fiber-reinforced..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing body structure of fiber-reinforced... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3035468