Single-piece molded frame for a composite lay-up skin

Abstract

The invention relates to a frame (2) including at least one part that is intended to support a skin (3) for receiving a part made from a composite material to be polymerized in an autoclave, said skin (3) defining the general shape of said part. The frame (2) is characterized in that it is a single-piece foundry piece.

Claims

1. A frame, at least one portion of the frame being configured to support a skin for receiving a part made of composite material to be polymerized in an autoclave, the skin defining the shape of the part, wherein: the frame is a single-piece foundry part, wherein the single-piece foundry part comprises longitudinal segments and cross members each having a thickness in a range from 8 to 12 mm, the at least one portion of the frame configured to support the skin is formed by a portion having a shape complementary to the skin, the shape complementary to the skin having a changing profile according to the shape of the skin, wherein the changing profile includes a curvature, and the frame is made of an alloy having a linear expansion coefficient lower than 7×10.sup.−6 K.sup.−1 at 200° C.

2. The frame according to claim 1, wherein the portion having a shape complementary to the skin includes protruding elements aimed at supporting the skin.

3. The frame according to claim 1, wherein the frame includes segments comprising longitudinal ribs.

4. The frame according to claim 3, wherein the segments each have a T-shaped cross-section and the segments define three longitudinal ribs.

5. The frame according to claim 1, wherein the frame is formed of three juxtaposed annular structures interconnected by cross members, and means for gripping, means for displacing, or means for gripping and displacing.

6. The frame according to claim 5, wherein the annular structures and the cross members each have a thickness in a range from 8 to 12 mm.

7. A support jig for receiving a part made of composite material for polymerization in an autoclave, the support jig comprising: the frame according to claim 1, and a skin for receiving the part, at least a portion of the frame carrying the skin, the skin defining a general shape of the part, wherein the skin is of a material having a grade identical to a grade of a material used for the frame.

8. The support jig according to claim 7, wherein the skin is a molded skin.

9. The frame according to claim 6, wherein the thickness of the annular structures and the cross members is about 10 mm.

10. The frame according to claim 2, wherein the frame includes segments comprising longitudinal ribs.

11. The frame according to claim 2, wherein the frame includes segments comprising longitudinal ribs, the segments each have a T-shaped cross-section and the segments define three longitudinal ribs.

12. The frame according to claim 3, wherein the frame includes segments comprising longitudinal ribs, the segments each have a T-shaped cross-section and the segments define three longitudinal ribs.

13. The frame according to claim 2, wherein the frame is formed of three juxtaposed annular structures interconnected by cross members, and gripping and/or displacement means.

14. The frame according to claim 13, wherein the annular structures and the cross members each have a thickness in a range from 8 to 12 mm.

15. The frame according to claim 3, wherein the frame is formed of three juxtaposed annular structures interconnected by cross members, and gripping and/or displacement means.

16. The frame according to claim 15, wherein the annular structures and the cross members each have a thickness in a range from 8 to 12 mm.

17. The frame according to claim 4, wherein the frame is formed of three juxtaposed annular structures interconnected by cross members, and gripping and/or displacement means.

18. The frame according to claim 17, wherein the annular structures and the cross members each have a thickness in a range from 8 to 12 mm.

19. A support jig for receiving a part made of composite material for polymerization in an autoclave, the support jig comprising: the frame according to claim 2, and a skin for receiving the part, at least a portion of the frame carrying the skin, the skin defining a general shape of the part, wherein the skin is of a material having a grade identical to a grade of a material used for the frame.

20. The support jig according to claim 19, wherein the skin is a molded skin.

21. The support jig according to claim 19, wherein the portion having a shape complementary to the skin includes protruding elements, wherein the protruding elements support the skin at a constant distance from the portion having a shape complementary to the skin.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a schematic perspective view of a support jig comprising a frame according to the invention;

(2) FIG. 2 shows a schematic perspective view from another angle of the same frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) When referring to FIG. 1, we can see a support jig 1 for receiving a part, not shown, made of composite material for its polymerization in an autoclave, comprising a frame 2 according to the invention supporting a skin 3 receiving a part made from composite material to be polymerized in an autoclave.

(4) In other words, the frame 2 permits to support a skin 3 on which is laid-up a pre-impregnated fabric for the production of a part made from composite material, before a polymerization in an autoclave or an oven.

(5) The shape of the skin 3 for receiving the part made of composite material defines the general shape of the part made from composite material.

(6) More specifically, the portion of the frame 2 intended to support the skin 3 is formed by a portion 22 having a shape complementary to the skin 3, as can be seen in the figures.

(7) As shown in the figures, the portion 22 has protruding elements 40 intended to support the skin 3 and to maintain it at a constant distance from the portion 22.

(8) The elements 40 may for example consist of barbs that are an integral part of the single-piece part, which forms the frame 2.

(9) The geometry of the frame 2 is of course adapted to the shape of the skin 3 being used.

(10) According to the invention, the frame 2 is a single-piece foundry part, through a molding process with lost mold and/or fusible core, so that it has no welds.

(11) The absence of welds on the frame 2 results into preventing its cracking during the thermal cycles of polymerization in an autoclave or an oven.

(12) The single-piece nature of the frame 2 permits to prevent it from twisting due to the repetition of thermal cycles of polymerization.

(13) In addition, even in case of expansion, since the frame 2 is a single-piece one, the expansion will be uniform and homogenous.

(14) According to the invention, the frame 2 includes segments comprising longitudinal ribs.

(15) According to a particular embodiment, which can be seen in the figures, the frame 2 includes segments having a T-shaped cross-section, so as to form three longitudinal ribs.

(16) According to the particular embodiment, which can be seen in the figures, the single-piece frame 2 is formed of three juxtaposed annular structures 21 interconnected by cross members 4, and also gripping means and/or displacement means 5.

(17) These three annular structures 21 are spaced apart by a substantially constant distance, so as to create an aerated frame structure 2 capable of permitting the air to circulate.

(18) These three annular structures 21 are capable of supporting the skin 3 for receiving the composite material to be polymerized, and have the advantage of reducing as much as possible the volume of material required to produce the single-piece part forming the frame assembly 2.

(19) Advantageously, these annular structures 21 have a T-shaped cross-section in order to increase the rigidity of the single-piece part of the frame 2.

(20) According to the embodiment of these figures, the assembly of these three annular structures 21 has, in the upper portion, the portion 22 including the cross members 4 and, in the lower portion, the gripping means and/or the displacement means 5.

(21) The cross members 4 have protruding elements 40 intended to support the skin 3 and to maintain it at a constant distance from the portion 22, namely from the cross members 4.

(22) Advantageously, the distance generated by the protruding elements 40 is as small as possible in order to minimize as much as possible the volume of the frame 2. In other words, the distance between the portion 22 of the frame 2, namely between the upper portion of the annular structures 21 and the skin 3, is preferably small in order to minimize the volume of the frame 2, but sufficient for the skin 3 not to be into direct contact with the entire portion 22 of the frame 2.

(23) This configuration has the effect of aerating as much as possible the single-piece part of the frame 2 for the circulation of heat to be as easy and homogeneous as possible.

(24) Since the frame 2 is intended to be inserted into an oven or an autoclave for the polymerization of a composite material, its aerated design permits to optimize the circulation of hot or cold air, as the case may be, within the oven or the autoclave.

(25) According to this particular embodiment, the upper portions of the annular structures 21, representing the portion 22 of the frame 2, have the same curvature as the skin 3.

(26) Thus, according to the invention, the assembly of annular structures 21, cross members 4, gripping and/or displacement means 5 is part of the same molded part, the whole being a single-piece part for forming the frame 2.

(27) In addition, in order to limit the energy supply necessary for the rise in temperature within the autoclave for carrying out the polymerization of the composite material, the thickness of the annular structures 21 and cross members 4 varies between 8 and 12 mm, is preferably 10 mm.

(28) This particular thickness permits the frame 2 to quickly reach its operating temperature within the autoclave for the polymerization of the composite material and to limit as much as possible the heat losses. Thus, an energy gain as well as an economic benefit are brought about.

(29) As can be seen in the figures, the gripping and/or displacement means 5 permit for example the displacement of the frame 2 inside or outside an autoclave and/or an oven with a lift-truck type system.

(30) According to another particular embodiment, the gripping means may namely consist of lugs present on said annular structures 21 and being an integral part of the single-piece foundry part formed by the frame 2.

(31) Preferably, the skin 3 and the frame 2 are made from the same material grade, or from material grades having similar physical-chemical characteristics and properties, in order to limit the deformations due to the difference in expansion coefficient between the two materials.

(32) Even more preferably, the material grade has a low expansion coefficient, which further limits the risks of deformation.

(33) As already mentioned, it can be very advantageous to manufacture the skin 3 by a molding process with the same material grade as the one used for molding the frame 2.