ES2356163T3 - USE OF CARBON FOAM COMPOSITE MATERIAL AND PROCEDURES TO USE THE SAME. - Google Patents

Abstract

Tool for producing at least one piece of composite material, the tool comprising a carbon foam tool body (400) and said carbon foam tool body (400) supporting a tool face material (405), characterized in that the coefficient of thermal expansion of the tool face material (405) and the carbon foam tool body (400) are equivalent.

Description

Field of the Invention

This invention relates to composite tooling and methods for using it, more specifically to incorporating carbon foam in a tool body to form parts made of composite materials.

Background of the invention

In general, composite materials are prepared by embedding a reinforcing material within a matrix material. Composite materials that have high degrees of utility typically show mechanical or other properties superior to those of the individual materials from which the composite material was formed. A common example of a composite material is fiberglass. Fiberglass are glass fibers, which are the reinforcement material embedded in a cured resin, which constitutes the matrix material.

It has been found that composite materials have a high degree of utility when used as parts of structures, components, subassemblies, and the like, of assemblies such as airplanes, missiles, ships, medical equipment and sporting goods. A composite material commonly used in such applications is fiberglass. Other composite materials that have particularly high degrees of utility in such applications are those that are prepared from carbon fibers combined with a matrix material such as thermosetting resins (for example thermosetting and the like) and / or thermoplastics. Such composite materials are called carbon fiber composite materials (hereinafter referred to as CFC), or more commonly, carbon composite materials. Carbon composite materials have been used, for example, as aircraft flight surfaces, missile bodies, orthopedic supports and golf clubs. The usefulness of such carbon composite materials is usually related to their strength ratio to exceptionally high weight and to their resistance to fatigue and corrosion. In most cases, these beneficial properties outweigh those of metals or other materials substituted by the use of carbon composites. Additionally, some types of carbon fiber composite materials can be carbonized to form carbon-carbon composite materials.

Specific fiber orientations may be desired in the final composite product to confer accentuated stiffness, stiffness and / or flexibility along certain axes. In addition, composite materials, particularly carbon fiber, are relatively expensive and the amount of waste is generally discouraging. Therefore, composite materials are produced in sizes, shapes and shapes that closely match those required by the desired application. In fact, composite materials, particularly carbon fiber composite materials used in aerospace applications and many others, are routinely produced within tolerances that are very restrictive to the required size.

The formation of composite materials, including carbon composite materials, for such a level of demand in terms of size, is normally carried out by the use of mold-like devices commonly called tools. These tools encompass one or more surfaces, called tool faces, whereby the composite material is formed, shaped, molded or otherwise produced giving rise to components of predetermined sizes and conformations. Such components may include structures, parts, subassemblies and the like. The tool face is a surface normally formed such that it is a precise three-dimensional negative mirror image of a surface of the desired composite component. That is, a raised surface on the composite part will be adjusted and formed by a surface depression equivalently sized (negatively) of the tool face. Likewise, a recessed surface on the composite part will be adjusted and formed by an elevated surface sized equivalently (negatively) of the tool face. In practice, a mixture of a reinforcing material and a matrix material, for example carbon fiber and a resin, are placed on the tool face by any of several methods and are brought into close contact with that tool face. The dimensions of the tool face are such that this contact effectively molds a surface of the mixture of matrix material and reinforcement material to give rise to the desired shape and dimensions. The matrix material is then solidified, usually by curing the resin, to produce the composite component. For example, a resin-containing carbon fiber is normally cured by the application of heat to give a solid CFC component that has a surface showing the conformation and dimensions conferred by the tool face.

In addition to the tool face, a tool also comprises a tool body and usually a support structure. The tool body comprises the tool face. That is, the tool face with which the composite material is formed, for example a CFC, is a surface of the tool body. The tool body can also cover a cover that encompasses at least the tool face, or a part thereof, so that an essentially closed volume is formed between the tool face and the cover. The support structure is connected to the tool body and can be for various purposes, including but not limited to, support, orientation and transport of the body and the tool face and together with protection against damage to the body and the tool face.

Important features of the tooling include, for example, quality, weight, strength, size, cost, ease of repair and the like. Additionally, stiffness and duration are considered to be very important features of the tooling. All these characteristics depend on the design of the tool, the construction materials of the tool and the materials used to form the composite material.

A characteristic of the tooling that is very important is the coefficient of thermal expansion (hereinafter referred to as CET and CETs in the plural form) shown by the tool face. When the tool face is a surface of the tool body, the CET shown by the tool face depends on the material of which the tool body is composed. In general it is desired that the tool face shows a CET that is substantially similar or equivalent to the CET of the formed composite part. Preferably, the CET shown by the tool face should be similar or equivalent to the CET of the composite piece formed over a wide temperature range. The importance of having a substantial similarity, or more preferably an equivalence, between the CET of the piece of composite material and that shown by the tool face is related to the way in which the pieces of composite material are prepared using the tools. That is, normally, the materials used to form the composite material are placed on the tool face at room temperature. Then the temperature of the tool and the composite forming materials is increased to some elevated temperature, usually such as 138.9 ° C (250 ° F) or more, to cure the composite resin. Once the resin has cured, the resulting composite piece, for example a CFC, is rigid. After curing the resin, the tool face and the composite piece are cooled to room temperatures. Such exposure to temperatures significantly higher than room temperature is the reason why it is desired that the CET of the tooling be adjusted to that of the resulting composite piece. For example, if the CET of the composite part is significantly lower than that shown by the tool face, the composite part can be trapped or retained in the tool by relatively superior contraction of the dimensions of the tool face with the cooling Conversely, if the CET of the composite part is significantly higher than that shown by the tool face, the part may be retained again in the tool or may damage the tool face during contraction or the dimensions of the composite material Curing may differ from those of the tool face.

Normally, carbon composites have relatively low CETs while CETs for most other materials are much higher. Therefore, it is very difficult to adjust the CET shown on the tool face with the CET of a carbon composite material since there are few materials available for the construction of the tool body having sufficiently low CETs. Such available low CET materials suitable for the construction of the tool body include, for example, other carbon composite materials, INVAR® (eg, a nickel alloy and controlled expansion iron), and the like.

INVAR® is durable and has a CET that is substantially similar to carbon composite materials. However, INVAR®-based tools are usually heavy, difficult to manufacture and may require, for example, up to seventeen separate manufacturing phases. These numerous manufacturing phases can lead to an increase of approximately 140% to approximately 250% in tooling costs and a four-fold increase in waiting times, as discussed in “Fabrication and Analysis of Invar Faced Composites for Tooling Applications ”, Proceedings of Tooling Composites 93, Pasadena, California, which is incorporated herein by reference.

Similar to INVAR®-based tooling, carbon fiber composite material-based tooling can adjust the CET of CFC parts, and the like, even for example, the difficult-to-adjust CET of low CET materials. For this type of tooling, carbon fiber composite materials are used as the total tool body and / or the part of the tool body that defines the tool face. Carbon fiber composite material-based tooling is advantageous since such CFC-based tools are less expensive, lighter, have a low thermal mass and require shorter wait times for tool fabrication than those of conventional tooling such such as those based on INVAR®. However, CFC-based tools are usually prone to damage if they are not handled with care, especially when composite material is found in them. Additionally, the surface degradation of CFC-based tools may occur as a result of the repetition of the process cycle due to a combination of component adhesion, lack of adjustment of the CET and oxidative decomposition. In addition, any necessary repair of CFC-based tools leads to an increase in repair and maintenance costs. In addition, CFC-based tools are subjected to dimensional stresses due to irregular support. Therefore, due to the problems mentioned above, CFC-based tooling is not commonly used.

There are other important features of composite material tooling, particularly CFC tooling, which should also be considered. For example, in addition to being rigid, durable, strong and adjustable CET, the tooling should also be low cost and easy to produce. That is, a factor normally considered when selecting the material for a tool body is the total number of parts to be produced. This consideration includes the fact that the production of a large number of parts can more easily justify expensive tooling. However, it is generally accepted that a rigid, strong, durable and adjustable CET tooling is desired, which can be easily produced at low cost, regardless of the number of parts planned.

Carbon foams are materials with a very high carbon content that have an appreciable empty volume. In their appearance, with the exception of color, carbon foams may resemble readily available commercial plastic foams. As with plastic foams, the empty volume of carbon foams is located within numerous empty cells. The limits of these cells are defined by the carbon structure. These cells normally approximate spheres or ovoids of regular size, conformation, distribution and orientation, but not necessarily uniform. The empty volumes in these cells normally connect directly with the surrounding empty volumes. An arrangement of this type is called an open cell foam. The carbon in these foams forms a structure that is continuous in three dimensions through the material. Normally, the cells in the carbon foams are of a size that is easily visible to the naked eye. In addition, the empty volume of carbon foams is such that it normally occupies much more than half the volume of carbon foam. The regular size, conformation, distribution and orientation of the cells within the carbon foam easily distinguishes this material from other materials such as metallurgical cokes. Carbon foams have been prepared from a variety of raw materials using a variety of processes. For example, raw materials for the production of carbon foam have included, but are not limited to, breasts, coals and carbon derivatives. Likewise, the processes for the production of carbon foams from each of these raw materials have been identified. Most of these processes include exposure of the carbon foam at an elevated temperature, sometimes up to about 3000 ° C, after foam preparation.

In Kuppusamy, Arvid, Develepment of framework for rapid tool manufacturing for RIDFT process, the use of carbon foam as a material in a RIDFT procedure is described. The carbon material is described as powdery, fragile and that breaks the silicone sheets.

In Advanced Materials and Composite News, vol. 25; No. 22, 11/17/2003, p. 5-6 a C foam is reported. This document generally describes that carbon foam can be used for tooling. In addition, it is identified that the material can be used in composite tooling according to the preamble of claims 1 and 11.

Summary of the invention

Tools are disclosed for the formation of composite parts from composite materials, which have tool bodies that comprise, at least in part, carbon foam. A surface of the built-in carbon foam can define at least a part of a tool face of a tool.

The carbon foam supports a tool face material, a surface of which defines at least a part of a tool face of a tool according to claim 1. The incorporated carbon foam can be partially or completely filled with a filler material. Part of the fillers can be carbonized after filling the carbon foam. The use of fillers can provide, for example, a smoother tool face and / or cause some areas of the carbon foam to become impermeable to the passage of gases or other materials. Tool face materials may include, but are not limited to, composite materials, in particular carbon fiber composites, resins, metals, including arc-sprayed metals, ceramic materials and other materials.

The tool faces of the tools disclosed may show thermal expansion coefficients (CETs) that are relatively low. Tool faces having such low CETs can be particularly useful for the preparation of low CET composite materials such as carbon fiber composite materials (CFC). For example, a tool body comprising carbon foam, in which a surface of the carbon foam is a tool face for the production of carbon fiber composite materials (CFC) is particularly advantageous since the CET of the Carbon foam can be adjusted to that of the resulting CFC. As another example, the carbon foam of the disclosed tools can support a tool face material, such as a CFC, a surface of which provides a tool face for the production of carbon fiber composite materials (CFC). . In this example, the CET of the carbon foam fits that of the tool face material and the resulting CFC.

The tools disclosed may be lighter, more durable and less expensive to produce and / or use than conventional tools used for the production of composite parts, particularly than the tools used for the production of CFCs. Additionally, such tools can be reusable, repairable and more easily modifiable than prior art tools.

In certain embodiments, the invention may include a tool for the production of at least one piece of composite material, the tool comprising a tool body in which at least a part of the tool body is carbon foam. A surface of the tool body defines a tool face, and a part of the tool face can be at least partially a surface of the carbon foam comprising the tool body. In some embodiments, the carbon foam cells may be at least partially filled with a filler material. The filler material may be a cured resin, a pitch, a cured moldable ceramic material, a carbonized resin, or a carbonized pitch. In certain embodiments, the coefficient of thermal expansion of the tool face is substantially similar to the coefficient of thermal expansion of the piece of composite material produced on the tool face. In further embodiments, at least a part of the carbon foam comprising the tool body at least partially supports a tool face material. The tool face material may be metals, ceramic materials, a cured resin, a fiber composite, a carbon fiber composite, a particulate composite, INVAR®, silicon carbide

or zircona ceramic materials. Carbon foam can be derived at least in part from pitch, coal or a carbon derivative. In other embodiments, the tool body may have a mandrel shape. Still further, the tool may further comprise a cover placed on at least a part of the tool face and enclose at least a part of the tool face. The tool may also include a resin reservoir connection hole in vacuum communication with the enclosed part of the tool face. The resin reservoir connection hole can be adapted to connect to a resin reservoir system and provides resin transfer from the resin reservoir system to the enclosed part of the tool face when a vacuum is created in the enclosed portion of the tool face.

Certain embodiments of the invention may also include a process for producing at least one piece of composite material, as defined in claim 11. The composite forming material may include a mixture of a resin and at least one selected from the group which consists of a reinforcement material of particulate material and a fibrous reinforcement material. The method may also include the step of placing a dividing film between the composite materials and the tool face. The method may also include the step of coating at least a part of the tool face with a release agent before contacting the tool face with the composite forming material. Still further, the tool may further include a cover placed on at least a part of the tool face and enclosing at least a part of the tool face, and the composite material forming material may be placed on the enclosed part of the tool. tool face A vacuum can be achieved within the enclosed part of the tool face.

Brief description of the figures

Figure 1 illustrates a cross-sectional representation of a reusable tool comprising a mandrel comprised partly of carbon foam. Composite forming materials are then placed on the outer surface of this mandrel to form a piece of composite material.

Figure 2 illustrates a cross-sectional representation of a reusable tool comprising a tool body comprised at least in part of carbon foam in which a surface of the carbon foam has been machined or contoured or otherwise formed until giving rise to a desired configuration to serve as a tool face.

Figure 3 illustrates a cross-sectional representation of a reusable tool comprising a tool body comprised at least in part of carbon foam in which a surface of the carbon foam incorporated in the tool body supports an impermeable material of the tool face A section of this tool face material has been machined or otherwise contoured or formed to a desired configuration to serve as a tool face.

Figure 4 illustrates a cross-sectional representation of a reusable tool comprising a tool body comprised at least in part of carbon foam in which a surface of the carbon foam incorporated in the tool body supports an impermeable material of the tool face A section of this tool face material has been machined or otherwise contoured or formed to a desired configuration to serve as a tool face.

Figure 5 illustrates a cross-sectional representation of a reusable tool comprising a tool body comprised at least in part of two mutually opposite sections of carbon foam in which a mutually opposite surface of each section of carbon foam supports a material of tool face, whose surfaces serve as tool faces.

Figure 6 illustrates a cross-sectional representation of a reusable tool comprising a tool body comprised at least in part of carbon foam in which a surface of the carbon foam incorporated in the tool body has been machined or has been contoured or otherwise formed to give rise to a desired configuration to serve as a tool face.

Figure 7 illustrates a cross-sectional representation of a first half of a reusable tool body comprised at least in part of carbon foam, which has a surface on which a channel and a conformation are formed.

Detailed description of the embodiments of the invention

Tooling can be used to make parts, including pieces of composite material, of various types, shapes, sizes and materials with high dimensional accuracy. The design of the tooling normally depends on the desired conformation of the piece to be formed, the materials used to form the piece, the amount of solidity and rigidity that the tooling must have to support the materials needed to form the piece, and / or of the procedure used to provide the materials to form the piece.

Tools encompasses one or more surfaces, called tool faces, with which the material is formed, shaped, molded or otherwise produced to give rise to a part (s) that has a surface (s) (s) of predetermined sizes and conformations. Such parts may include, but are not limited to, structures, parts, subassemblies, component parts, partial components, and the like, including any solid form having a shaped surface. The tool face is a surface of the tool body, normally formed to be a precise three-dimensional negative mirror image of a desired surface of a part. That is, a raised surface on the part, for example a piece of composite material, will be adjusted and formed by a surface depression equivalently (negatively) sized of the tool face. Likewise, a recessed surface in the part will be adjusted and formed by means of a high surface dimensioned in an equivalent way (negatively) of the tool face.

In practice, materials comprising a piece of composite material can be placed on the tool face by any of several procedures. Commonly, composite materials use a resin (s) as matrix material and fiber as the reinforcing material. However, a resin (s) and a particulate material (s) can also be used as the matrix and reinforcing material, respectively. Sometimes the placement of the fiber is closely controlled so that the resulting composite piece shows a specific separation and / or orientation of fibers. The fiber and resin can be mixed or otherwise combined before the placement of the tool face. Alternatively, the fiber can be placed on the tool face and the resin can be subsequently perfused into the fiber by any of several methods. In some cases, before the placement of the materials comprising the composite material, the tool face can be covered with a thin sheet of material, sometimes referred to as a split sheet or release film, which forms closely with the tool face . Such sheets can be considered as a temporary coating on the tool face. The surface of this sheet that is not in contact with the tool face, that is, the outer surface of the sheet, effectively becomes the tool face. Such sheets can be used to protect the tool face and / or to provide easier removal or release of the formed composite part. Alternatively, it can be avoided that the materials comprising the composite material bind to the tool face by coating the tool face with a release agent. The release agents may include various polymers, including PVA and waxes, among other materials. The release films may be composed of any of several polymeric materials that do not bond with any of the materials comprising the composite material. Many types of materials, films, compounds and release agents are known in the associated techniques and can be used with the present invention.

The dimensions of the tool face can be such that a surface of the materials comprising the piece of composite material, commonly a resin-containing fiber, is effectively molded to give rise to the desired shape and dimensions. The resin (s) included in the materials comprising the piece of composite material can be subsequently cured, usually by the application of heat, to give a piece of solid composite material that has a surface of the conformation and the dimensions conferred by The tool face. It is not uncommon for such heat to be applied in an oven or autoclave. The use of an autoclave can also provide the formation of composite parts at high pressures.

In addition to the tool face, a tool comprises a tool body and usually a support structure. The tool body defines the tool face. That is, the tool face with which the composite part is formed is a surface of the tool body. The support structure, if present, is connected to the tool body and can serve several purposes, including but not limited to, support, orientation and transport of the body and the tool face together with protection against damage to the body and the tool face

Carbon foam is usually a light, strong, open-cell, durable, stable, easily machined and relatively non-reactive material. Carbon foams can also show very low thermal expansion coefficients that can be essentially equivalent to those of carbon fiber composites. The carbon foam TSC can be modified by controlling the maximum temperature at which the carbon foam is exposed during preparation or by selecting that of the raw material of the material used to prepare carbon foam.

The tools of the present invention have tool bodies that incorporate carbon foam. The tool bodies may be composed entirely or partially of carbon foam. The carbon foam of the individual tool bodies may be one or more unique pieces of carbon foam. If the individual tool bodies are composed of more than one piece of carbon foam, adhesives, resins, and the like can be used to join the multiple pieces of carbon foam. If they are partially composed of carbon foam, the tool bodies are constructed such that the CET of the tool face is substantially similar or equivalent to that of the carbon foam and the pieces of composite material (s), particularly Carbon fiber composite material (s), prepared therefrom. If the tool body is composed entirely of carbon foam, this carbon foam may have a CET substantially similar or identical to that of the composite material, particularly carbon fiber composite material, and the formed parts thereof.

The tools of the present invention can be reusable, repairable and more easily modifiable than the tools of the prior art. That is, since they are reusable, the tools of the present invention can be used to sequentially produce more than one piece of composite material. Carbon foam, comprising at least a part of the tool body of the tools of the present invention, can be joined using conventional adhesives, resins and the like, and can be machined to give rise to narrow tolerances using hand tools and / or tools. Easily available machine. As a result of these characteristics, the tools are repairable so damaged sections of carbon foam used in a composite material that forms the tool can easily be replaced by undamaged carbon foam. In addition, these characteristics of the carbon foam provide the ability to easily replace sections of carbon foam used in a composite material that forms the tool so that the sections of a tool face can be modified, as desired, without replacing all The tool face.

In the present invention, a surface of the carbon foam incorporated in the tool body serves to support other materials that define at least a part of the tool face or the entire tool face. When defining the tool face, a surface of the carbon foam or other materials has sufficient geometry or configuration to confer the desired configuration to a surface of the composite part formed therein. These other materials, referred to herein as tool face materials, have CETs substantially similar to or identical to those of the carbon foam and those of the composite part, particularly a carbon composite part, prepared therein. . The tool face materials for the production of CFC parts can be carbon composite materials.

The tool face materials can be used in an amount or form so that the observed CET of the tool face is substantially similar or equivalent to that of the carbon foam and composite piece, particularly a composite piece of carbon, prepared in it.

Both the carbonaceous foam of the tool body, and the part of the tool face of the tool body, including any tool face material, may have CETs substantially similar to or identical to the CET of the resulting composite part formed on the face of tool. In a further embodiment, at least a part of the tool body, particularly the part of the tool body that supports and / or defines the tool face, and the tool face, can be adjusted to have a low CET. The CET of the carbon foam may normally be low and substantially similar or identical to those of carbon fiber composites. Therefore, the use of the tooling of the present invention to manufacture carbon fiber composite materials, usually of controlled dimensions, is particularly favored. It should be noted that it is possible to vary the CET of the tool face by judicious selection of the tool face materials. It is also contemplated that the CET of the tool body can be varied by selecting the raw material and / or controlling the process conditions used to produce the carbon foam. Such process conditions may include, but are not limited to, the maximum temperature at which the carbon foam is exposed during foam production.

The carbon foam incorporated in the tool bodies of the present invention can be manufactured with various predetermined geometries to provide tool faces that reflect those geometries. Alternatively, a tool face material may be formed or otherwise manufactured with various predetermined geometries to provide tool faces that reflect the desired geometries. These geometries are then incorporated into a surface (s) of the composite part formed with the tooling. The tool face (s) defines at least one surface of at least one piece of composite material formed with the tooling. There can be a plurality of different tool faces arranged in the same tool body. In addition, the tooling of the present invention can be used with other types of tooling known.

The use of a dividing film is usually required to prevent the bonding of composite forming materials to carbon foam. Even with the use of a dividing film, the cell size of the carbon foam can be reflected in the possible surface modeling of the resulting composite piece. This size of this modeling can be modified by the use of carbon foams that have other cell sizes in the tool body and the resulting tool face. Carbon foams of different cell sizes can be used in a tool body. For example, a small, dense cell foam can be used to define the tool face while a lighter, large cell foam can be used to support the denser carbon foam that defines the tool face. Alternatively, a tool face can incorporate both small cell and large cell foam surfaces. The surface modeling of the resulting composite piece will then reflect the use of carbon foams of different cell sizes.

A surface modeling of this type can be minimized or eliminated by filling the cells, that is, the internal void volume of the carbon foam, with a filler material. Fillers may include, but are not limited to, cured resins, breasts, cured moldable ceramic materials, and the like. Some fillers, including but not limited to cured and breasted resins, can also be carbonized to produce a carbon filler material. The carbon foam can be filled partially or completely with the filler material. For example, only the volume of the carbon foam that is closest to the tool face can be filled with the filler material. Alternatively, a fraction of the entire internal void volume of the carbon foam can be filled. A filling of this type can be complete so that each cell is fully loaded with filler material or it can be incomplete so that each cell is only partially filled with the filler material. Partial filling of carbon foam cells will minimize modeling. However, a smoother tool face will be provided by completely filling the carbon foam cells at least on the surface tool face. Additionally, a smoother surface may provide the use of a releasing agent, instead of a dividing film, to prevent the bonding of the composite materials to the tool face. Complete filling of the carbon foam cells in a certain volume of the foam surrounding the tool face, possibly including the filling of the carbon foam cells on the surface tool face, with a filler material may be required Gas impermeable for those cases in which it is desired that there is a vacuum above the tool face. Additionally, the carbon foam cells can be partially or completely filled with a filler material to increase the mechanical properties, such as the strength, of the foam.

A carbon foam having only partially filled cells with a filler material is expected to show a CET essentially equivalent to that shown by the foam before filling the cells. It is also expected that a carbonized filler material can have very little effect on the CET of the carbon foam regardless of the degree of filling of the cells. Filling the cells with other materials may result in the foam showing different CETs before and after filling. The TSC observed after filling the cells may be between that of the carbon foam and that of the filler material. Alternatively, if the filling material of the cells is sufficiently compressible, the observed TSC may be that of the carbon foam. As described above, carbonized fillers may have CET values that are very close, or even equal, to those of the carbon foam of the tool face. In this case, the CET of the tool face would be that of the carbon foam.

In another embodiment of the present invention, the material, which may be referred to as tool face material, may be formed, deposited, coated, layered, fixed or otherwise placed on a surface of the carbon foam of the tool body, to provide at least a part of a tool face. Relatively thick or relatively thin layers of tool face material (s) may be used, depending on the properties of the tool face material and the desired uses of the surface to which the tool face material is applied. The tool face material can cover the entire tool face. The tool face material can also cover tool body surfaces that are not tool faces. Normally, covered surfaces that are not tool face may come into contact with the resin or other materials used to form the composite part. Carbon foam can be machined or contoured or otherwise formed to produce a surface that has a specific conformation before the formation and / or deposition of the tool face material. The formation or deposition of the tool face material on such a conformation can then produce a tool face having the desired configuration and dimensions. Alternatively, after formation and / or deposition of the tool face material on the carbon foam surface, this material can then be machined or formed or otherwise contoured to provide a tool face of the desired geometry. The machining of the carbon foam or tool face material can be controlled more precisely to give rise to the desired dimensions by incorporating control marks, fixing bolts, or the like, inside or on the tool body before Start of any precision machining operation.

The use of a tool face material can provide a very smooth tool face of high dimensional accuracy. The use of tool face materials can also provide easy removal of the formed composite part. Normally, split films or release agents can be used with the tool faces provided by the tool face materials. Additionally, the CET of a tool face material can be adjusted with the CET of the resulting composite part and is adjusted with the part of the tool body that supports the tool face material. Such an adjustment can guarantee the dimensional and structural accuracy and precision of the piece of composite material formed. Additionally, such an adjustment can provide subsequent cure of the parts on or in the tool, as opposed to independent curing.

The CET of the tool body, the tool face, the tool face materials and the composite part are substantially similar or equivalent. The term "substantially similar" or "equivalent" CET as used herein may refer to CET values that are sufficiently close in magnitude such that the piece of composite material produced has the desired critical dimensions and is not trapped. or retained in, or jump from, the tool by the effect of non-equivalent expansions and contractions of the piece of composite material and the tool face, or, are those that have values that are sufficiently close in magnitude so that the face of The tool is not damaged by the effect of non-equivalent expansions and contractions of the composite part and the tool face.

It is envisioned that such a case can provide a procedure that achieves a tool face CET that is not easily obtained by other procedures. It is also envisioned that the tool faces composed of thin layers of tool face materials show the CET of the underlying carbon foam. This would be expected to occur especially with very thin layers of tool face materials that have certain elastic properties.

Several different materials, alone or in combination, can be used as a tool face material as long as they meet the definition of claim 1. These materials include, for example, cured resins, including phenolic, polyimide, BMI and epoxy resins, prepreg materials, adhesive films, coatings, and the like, either alone or in combination. The tool face material can also be, for example, a composite material, including fiberglass, carbon fiber, carbon-carbon, and other similar materials including other fiber and particulate composites. Additionally, the tool face material may be INVAR®, silicon carbide, zircona ceramic materials, and other metals and ceramic materials. These types of tool face materials can be deposited on the carbon foam to form a tool face using techniques including, but not limited to, arc and flame spraying and vapor deposition. Suitable tool face materials can be essentially gas impermeable. Metals, ceramic materials and carbon composites that have low CETs are particularly useful tool face materials, especially for the tools used to produce CFCs.

A vacuum may occur within a carbon foam tool body to aid in the placement of resin tool face materials and / or resin-based composite material. Additionally, any unwanted surface porosity shown by any tool face material after placement on the tool body can be filled by coating the tool face material with a thin layer of resin. The permeation of such thin layers of resin can be aided within any surface porosity of the tool face material by producing a vacuum within the carbon foam tool body.

The tool face can also be formed so as to impart a texture to a surface of the composite part formed by tooling. An inscription can be made on the tool face with a dimensionally negative pattern so that the positive image of this pattern will be transmitted to a surface of the formed composite piece. Such patterns may include any combination of a plurality of different textures, cross-hatched, plot lines, and the like to establish the conformation and / or external texture of the composite piece. Additionally, the surface of the tool face (s) may not be homogeneous. For example, one part of the tool face (s) has a first texture while other parts of the tool face have different textures.

The geometries of the tool body can be similar to a mandrel. In this case, the tool face would then be the outer surface in this way similar to a mandrel. Then paper, textile and fiber impregnated with resin, and the like, can be placed on the surface of the mandrel (i.e., the tool face) by manual or automatic means to form a piece of composite material having a surface, usually a surface interior, whose dimensions reflect those of the outer surface of the mandrel.

In addition, the tool faces may be in the form of a male part and / or a female part having cavities and / or protrusions with opposite conformations on opposite tool faces. In the present invention, at least a part of one of the opposite tool faces is identified by the carbon foam incorporated in the tool body, or is defined by a surface of a tool face material supported at least in part by Carbon foam body tool. An empty volume between such opposing tool faces can be filled with composite forming materials. After curing these materials, the conformation of the resulting composite piece will double that of the empty volume between the male and female tool faces. It is also possible to have a single tool body that has at least one surface that provides a tool face or a surface of the walls of a cavity that serves as the tool face (s). A cover can be incorporated in the tool body. Such a cover can be a flexible cover, in which the cover can comprise an elastomeric plastic material, such as a silicone elastomeric sheet or membrane, or other material similar to a flexible sheet. The cover can be placed on the surface or cavity to form a closed volume. Then a vacuum can occur in the resulting closed volume. The force of the atmospheric pressure outside the closed volume then causes the cover to deform and come into contact with the composite forming materials. This contact forces these materials against the surface or walls of the cavity. After curing of the composite material formation materials, a piece of composite material can be produced that has the conformation of the surface or the walls of the tool body cavity.

Composite forming materials that may be suitable for forming pieces of composite material using the tools of the present invention include those materials known in the relevant techniques. Suitable matrix materials include, but are not limited to, resins, prepreg materials, vinyl esters, adhesion films and coatings. The resins can comprise any family of thermoplastic or thermostable resins and can be catalyzed. Other examples of suitable matrix materials are epoxy resins. Such resins are generally formed from low molecular weight bisphenol A diglycidyl esters. Depending on the molecular weight, such resins can range from liquid to solid resins, and can be cured with amines, polyamides, anhydrides or other catalysts. Suitable solid resins can be modified with other resins and unsaturated fatty acids. Epoxy resins may be particularly suitable since they have good adhesion to fibers and because their thermal expansion can be adapted to match that of carbon foam based tooling when combined with certain fibers. In addition, its low viscosities are effective in wetting various reinforcing materials. More specifically, resins suitable for use in the manufacture of composite parts can comprise any combination of commercially available resins, for example, Dow 330, Gougeon WEST, Gougeon XR02-099-29A, ProSet 125, ProSet 135, ProSet 145 and MGS. In addition, commercially available resins used in tooling face materials may comprise, for example, PTM & W HT2C, AirTech Toolmaster 2001, JD Lincoln L-956 and Vantico RP 4005. Additionally, composite parts can be produced in the tooling of the present invention using vinyl esters. The matrix materials useful in the present invention can also encompass catalysts, hardeners and other curing agents used to initiate polymerization or hardening of the matrix material system. For the purposes of this specification, suitable matrix materials will be collectively referred to herein as resins.

Prepreg materials are also suitable for use as composite material forming materials for the production of composite parts using the tooling of the present invention. Prepreg materials is an abbreviation of preimpregnated materials and include those reinforcement materials that are combined with an uncured matrix material before placement on the tool face. Prepreg materials can comprise any combination of felt, textile material, nonwoven material, and resin wick. Normally, these are usually cured until phase B, ready for molding. Additional examples of prepreg material include mixtures, such as, JD Lincoln L-526, epoxy resin / carbon blends, such as JD Lincoln L-956, ACG, and AirTech Toolmaster, and epoxy resin / glass blends, such as Bryte, and the like In addition, commercially available prepreg material used for tool face materials may comprise combinations of epoxy resin / carbon, for example, JD Lincoln L-956, ACG, and AirTech Toolmaster.

In addition, composite pieces can be produced in the tooling of the present invention using adhesion films. Adhesion films are a thin, dry resin film, usually a thermosetting resin, used as an interleaved sheet in the production of laminated materials such as plywood. The heat and pressure applied in the lamination process can cause the film to join both layers together. Some commercially available adhesion films include, but are not limited to, JD Lincoln L-313 Epoxy, SIA-MA-562, and SIA-PL-7771 FR.

The reinforcing materials used in the composite materials produced in the tooling of the present invention may include any of those known in the relevant techniques. Such materials may include, but are not limited to, carbons (including graphites), Kevlar, aramid, glass and the like in forms that include, for example, fibers, including unidirectional fibers and staple fibers, woven materials and nonwoven materials and cloth materials. . Particulate reinforcements can also be used.

Reinforcement structures can also be added to composite forming materials while these materials are placed on the tool face. Such reinforcing structures may, for example, reinforce the resulting composite piece and / or form the base to join the composite piece to result in an assembly. These reinforcing structures may include shapes such as bars, tubes, sheets, screens, flat pieces, plates and the like, of any specific geometric configuration. The materials of which such reinforcing structures are composed can include essentially any solid material of appreciable strength that has adequate compatibility with both the composite forming materials and with any associated curing condition. Such materials may include metals, ceramic materials, plastics, wood, glass, previously cured composite materials, and the like. In practice, the reinforcing structures can be immersed in, or placed against a surface of, the composite material forming materials on the tool face. After curing the composite materials, the reinforcing structures can be more firmly attached to the resulting composite piece by using screws, staples, adhesives, and the like if desired or required. Specifically, such reinforcing materials may have CETs that are substantially similar or identical to those of the resulting composite piece.

Various composite forming techniques can be used in conjunction with the tools of the present invention. These techniques are well known to those skilled in the associated techniques and include, but are not limited to, manual lamination, automatic lamination, manual spraying, automatic spraying, resin transfer molding (RTM), and vacuum assisted resin transfer molding ( VARTM). Additionally, any combination of such procedures can also be used.

Resin transfer molding is a process whereby liquid thermoset polymeric resins are transferred within a volume that can be confined, such as, for example, a cavity or a channel within or on a tool body or body surface of tool. Reinforcements can be distributed, such as fibers cut into the resin before distribution. Alternatively, a fiber reinforcement can be placed within the volume, particularly in the area of the volume defined by a tool face. RTM is usually implemented by transferring or injecting catalyzed resin, examples of which include polymers of epoxy resin, vinyl ester, methyl methacrylate, phenolic resin and polyester inside a tool volume defined at least partially by one ( s) tool face (s). The resins fill the volume and prefund inside the reinforcement materials that have been previously placed within the volume. Care must be taken in this procedure to avoid the run-over of gas bubbles, since gas bubbles can weaken the resulting composite. Typical reinforcements include fiberglass and carbon fibers.

A vacuum system can also be used to aid in the transfer of the resin in and through the volume of the tool. This process is called vacuum assisted resin transfer molding. With an adequate forecast, a vacuum system can be used in many composite material formation processes. It should be noted that for the purposes of this specification, a vacuum system is a system that can reduce the internal gaseous pressure of a closed volume, connected to the vacuum system, to pressures significantly below ambient atmospheric pressure. That is, a vacuum system will evacuate an enclosure, including a closed volume. Vacuum systems usually consist of a vacuum pump and are associated with pipes

or connection tubes.

Additionally, the extraction of air from composite material formation materials, during the formation of the composite part, by using a vacuum system can help ensure the dimensional and structural accuracy and precision of the composite part. formed. That is, an extraction of air of this type can reduce, or even eliminate, the formation of air bubbles in the resulting composite piece. Such bubble removal can result in stronger pieces of composite material. The extraction of air is usually practiced by producing at least a partial vacuum in a closed volume containing the composite material formation materials. Additionally, the production of a vacuum in a closed volume of this type, if that volume is defined by at least one flexible cover or wall, can result in the composite being compressed, usually by its design, against the tool face. through the action of the ambient atmospheric pressure on the roof or flexible wall.

More specifically, the closed volume can be formed, for example, by closing and sealing openings, holes and / or limits that have access to the volume. This can be done with a vacuum bag, including, for example, a sheet of flexible material, a purge cloth and a release film placed above and / or below the composite laminate in the tool, and edges of the sheet, which are sealed to create a closed volume. A vacuum system is connected to the closed volume containing the purge cloth, the release film and the composite laminate. The trapped air is mechanically expelled from the composite laminate and removed from the vacuum system. The piece of composite material is then cured over time under controlled conditions of temperature and pressure. Depending on the material to form the piece of composite material and / or the characteristics of the final product, the material to form the piece of composite material can be cured, at temperatures ranging from about room temperature to about 400ºF and vacuum pressures ranging from about 0 to about 28 in Hg. These intervals depend on the type of resins used. That is, any suitable temperature and / or pressure can be used.

Carbon foam can also be incorporated into existing composite tools to provide the benefits of the present invention. An incorporation of this type may be to improve, repair or otherwise provide any benefit of the present invention. Such an incorporation is fully incorporated within the scope of the present invention.

An embodiment of the present invention relates to a tool body comprised at least in part of carbon foam. A surface of the carbon foam, comprising at least a part of the tool body, supports a tool face material. A surface of the tool face material, which in this embodiment is a carbon fiber composite material, defines a tool face. The carbon foam is prepared or selected so that the CET of the carbon foam is substantially similar or equivalent to that of the cured composite materials that will be formed by the tool. In use, the tool face is coated with a release agent. Carbon composite forming materials are then placed on the tool face to provide essentially uniform coverage of the tool face. Composite forming materials can be pressed against the tool face. The composite materials are then cured at an elevated temperature to provide a carbon fiber composite, which is then removed from the tool.

Reference will now be made in detail to other embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Various aspects of these embodiments may be combined with the teachings of the present invention to provide additional examples that are not specifically explained. Therefore, it is intended that these embodiments be illustrative only of the present invention and not considered limiting of this invention.

Figure 1 illustrates a first exemplary embodiment of a tool and a system for manufacturing at least one piece of composite material, according to this invention. This tool uses a tool body similar to a mandrel to form a piece of composite material.

Figure 1 illustrates a cross-sectional representation of a reusable tool comprising a mandrel 100 that rotates on a shaft 110 included in a counterclockwise direction as indicated by the arrow in Figure 1. The mandrel comprises carbon foam 120. The outer surface of the carbon foam is coated with a tool face material 130 as shown in this example. The tool face material may be a carbon composite material.

Alternatively, the carbon foam cells, at least the cells on the carbon foam surface, may be filled with a filler material. The outer surface of the mandrel is the tool face 140. The tool face 140 is preferably coated with a release agent. A bundle of longitudinally arranged fibers 150, of appreciable length, is directed until it comes into tangential contact with the rotating mandrel 100 so that it is stretched from the fibers (i.e., rolled), usually under tension, around the circumference of the mandrel rotary. The fibers may be of any type known to be effective composite reinforcement materials. Such fibers may be composed, for example, of glass or carbon. The fibers are pre-fused with a resin before, during, and / or after coming into contact with the mandrel. Alternatively, a longitudinally arranged fiber prepreg material can be used as the fiber bundle. The precast fiber bundle with prepreg or resin material is stretched around the circumference of the mandrel until the desired thickness of the precast fiber with prepreg or resin material is obtained. Normally, the tangential contact of the fiber bundle with the mandrel moves parallel to the axis of rotation of the mandrel so that the fibers pre-fused with prepreg fiber or resin are positioned uniformly along the length of the mandrel. Once the desired thickness of the precast fibers with prepreg material or resin is obtained, the fiber is no longer supplied to the mandrel and the rotation of the mandrel is stopped. Then the precast fiber is cured with prepreg material or resin that covers the mandrel. Heating of the precast fiber covering the mandrel is preferred or is required for some prepreg materials and resins to cure. Heating can be carried out by using an autoclave, oven, individual heating element and / or other similar heating devices. The individual heating elements may be external to or internal to (i.e. embedded within) the tool body. Once cured, the resin precast fiber coating constitutes a piece of composite material. The piece of composite material can then be removed from the mandrel. When heat is used to cure the composite material, the relative CET values of the mandrel and composite material become important. If the CET of the composite piece is less than or essentially equivalent to that of the mandrel, the composite piece can be easily removed from the mandrel. However, the inner dimension of the composite piece may be larger than the outer diameter of the unheated mandrel. If the CET of the composite part is greater than that of the mandrel, the component part can be “locked” in the mandrel, it being difficult, if not impossible, to separate the mandrel without damage.

It should be noted that the mandrel does not have to rotate as shown in this embodiment. For example, the mandrel can rotate clockwise. Alternatively, the mandrel may be stationary while the bundle of fibers pre-fused with prepreg or resin material is directed such that it is wound around the outer circumference of the stationary mandrel.

Figure 2 illustrates a second tool and a system for manufacturing at least one piece of composite material, which is not according to this invention.

Figure 2 illustrates a cross-sectional representation of a reusable tool comprising a tool body 200 comprised at least in part of carbon foam. A surface of the carbon foam incorporated in the tool body has been machined or otherwise contoured or formed to a desired configuration and serves as the tool face 210. This tool face extends along the surface of the carbon foam from 210-A to 210-B. This surface of the tool face is covered with a non-permeable partition sheet 220. The dividing sheet covers not only the tool face but also the surfaces surrounding the tool face to avoid unwanted contact of other tool surfaces with composite forming materials. Composite forming materials 230 are placed on the dividing sheet that covers the tool face. These composite materials are placed, mechanically or manually, on the area of the dividing sheet that covers the tool face so that an essentially uniform distribution of these materials is obtained. Composite forming materials are also pressed against the dividing sheet that covers the tool face. This pressure is made to ensure that the composite formation materials adapt to the configuration of the tool face. In addition, since the tool face is unfilled carbon foam, it will confer a certain type of modeling, representative of the unfilled carbon foam cells on the tool face, to the defined surface of the tool face of the part of composite material.

The composite material formation materials are then cured to produce a piece of composite material that has the shape conferred by the tool face. Heating or heating of composite materials is preferred or required for some composite materials to cure. Heating can be carried out by using an autoclave, oven, individual heating element and / or other similar heating devices. The individual heating elements may be external to or internal to (i.e. embedded within) the tool body. As discussed above, heating will effect changes in the dimensions of all heated materials. The magnitudes of such dimensional changes depend on the CETs of the individual materials. For this, and all the examples included in this specification, the CET of the tool face and the resulting composite part are preferably similar or essentially identical, as would be the case if the resulting composite part was a CFC . If the CET of the composite part is not similar or essentially identical to that of the tool face, the size of the composite part may not adapt to the desired critical dimensions. In addition, if the CET is higher than that of the tool face, the component part may become "blocked" on the tool face, it being difficult, if not impossible, to separate the tool face without damage.

This example can be modified in various ways. According to the invention, the tool face can be a surface of a tool face material supported by carbon foam. Or, the carbon foam tool face cells can be completely filled with a filler material. For both modifications, it may be possible to replace the partition sheet with a release agent. Other modifications will be apparent to those skilled in the associated techniques.

Figure 3 illustrates a third exemplary embodiment of a tool according to this invention.

Figure 3 illustrates a cross-sectional representation of a reusable tool comprising a tool body 300 comprised at least in part of carbon foam. A surface of the carbon foam incorporated in the tool body supports an essentially gas-impermeable tool face material 310. A section of the exposed surface of the tool face material is contoured or otherwise shaped to give rise to a desired configuration to provide a tool face 320. The tool face extends from 320-A to 320-B. The surfaces of the tool body near the tool face 330 are also coated with gas impervious tool face material. A gas-impermeable cover 340 encloses the tool face, the tool body surfaces near the tool face, and the composite materials 350. The cover may be made of a flexible material, such as, for example, plastic, or of rigid material, such as, for example, carbonaceous foam, metal, and the like.

If carbon foam is used as a cover, at least the surface (s) of the carbon foam that is expected to come into contact with the composite forming materials with a tool face material, a coating can be coated. cell filling material or a dividing sheet. That is, the use of carbon foam as a cover can be practiced in much the same way as when carbon foam is incorporated into a tool body as described by the present invention. Coating of a carbon foam cover is required if that cover is going to be impermeable to the passage of gases. Additionally, any rigid material used as a cover can be contoured, formed or otherwise formed on the surface that is expected to come into contact with the composite material forming material to form a tool face on the opposite side of the forming materials. of composite material of that tool face of the tool body. This second tool face will then form a surface of the composite material formation materials. This surface will be on the opposite side of the resulting composite part than that of the surface produced by the tool face of the tool body. Division sheets and release agents can be applied to any surface, especially those that are expected to come into contact with composite forming materials.

The intersection of the tool body and the cover forms an opening 355 around the entire perimeter of the intersection. This opening can be sealed with various 360 materials as required to produce an air or gas impermeable limit. Suitable materials are those that will provide cover contact with composite materials while still providing a sealing action. For example, the opening can be sealed with adhesive tape, sealing gasket material, insulator, seal, and the like. A connection hole 370 is located in the cover of the tool body (as shown in Figure 3), or the opening such that this connection hole accesses the volume defined by the tool body, the tool face, the cover and any sealing material of the opening. A vacuum system 380 is connected to this connection hole.

If the opening and the connection hole are sealed or otherwise closed, the composite material forming materials on the tool face are therefore contained within a closed volume 390. This closed volume can be sealed essentially tightly when the surfaces of the tool body and the cover, and the opening between the tool body and the cover are sealed or otherwise made impermeable to the passage of gases.

In use, the composite forming materials are placed on the tool face and the opening between the tool body and the cover is sealed except for the connection hole. The operation of the vacuum system removes the air from the closed volume and the composite material formation materials contained within the closed volume. The operation of the vacuum system also causes the cover to be pushed towards the outer limit of the composite forming materials by the action of local atmospheric pressure. Then the cover presses these materials against the tool face. In addition, if the cover is made of a rigid material, the conformation of the cover influences the conformation of the surface (s) of the piece of composite material adjacent to an inner surface of the cover. That is, a rigid cover can function as a second tool face.

The composite material formation materials are then cured to produce a piece of composite material that has the shape conferred by the tool face. Heating or heating of composite materials is preferred or required for some composite materials to cure. The tool and cover assembly can be placed in an autoclave to apply additional pressure to the cover and / or to heat the composite formation materials to cure. Other devices such as an oven, and / or individual heating elements may be used to apply heat to the materials contained within the closed volume in order to cure the composite formation materials contained therein to result in the workpiece. composite material. If desired, the individual heating elements may be embedded within the tool body. Depending on the properties of the resin used to form the composite material, room or ambient temperature may be sufficient, for example, to cure the materials to form the composite piece.

As discussed above, heating will effect changes in the dimensions of all heated materials. The magnitudes of such dimensional changes depend on the CETs of the individual materials. Preferably, the CET of the tool face and the resulting composite part are substantially similar or equivalent, as would be the case if the resulting composite part and the tool face material were CFC.

Figure 4 illustrates a fourth exemplary embodiment of a system according to this invention.

Figure 4 illustrates a cross-sectional representation of a reusable tool comprising a tool body 400 comprised at least in part of carbon foam. A surface of the carbon foam incorporated in the tool body supports a waterproof tool face material 405. A section of the exposed surface of the tool face material is contoured or otherwise shaped to give rise to a desired configuration to provide a tool face 410. The tool face extends from 410-A to 410-B. The tool body surfaces near the tool face 415 are also coated with waterproof tool face material. A cover 420 encloses the tool face, the tool body surfaces near the tool face, and the composite reinforcement materials 425. The composite reinforcement materials may be fibers. The cover may be made of a flexible material, such as, for example, plastic or a rigid material, such as, for example, carbonaceous foam, metal, and the like.

If carbon foam is used as a cover, the surface (s) of the carbon foam that is expected to come into contact with the composite material forming materials with a tool face material, a material can be coated cell filling, or a dividing sheet. That is, the use of carbon foam as a cover can be practiced in much the same way as when carbon foam is incorporated into a tool body as described by the present invention. Coating of a carbon foam cover is required if the cover is to be impermeable to the passage of gases. Additionally, any rigid material used as a cover can be contoured, formed or otherwise formed on the surface that is expected to come into contact with the composite material forming material to form a tool face on the opposite side of the forming materials. of composite material of that tool face of the tool body. This second tool face will then form a surface of the composite material formation materials. This surface will be on the opposite side of the resulting composite part than that of the surface produced by the tool face of the tool body. Division sheets and release agents can be applied to any surface, especially those that are expected to come into contact with composite forming materials.

The intersection of the tool body and the cover forms an opening 430 around the entire perimeter of the intersection. This opening can be sealed with various materials 435 as required to produce an air or gas impermeable limit. Suitable materials are those that will provide cover contact with the material materials while still providing a sealing action. For example, the opening can be sealed with adhesive tape, sealing material, insulator, seal and the like. A first connection hole 440 is located on the cover (as shown in this example), or the opening 430 so that this connection hole accesses the volume defined by the tool body, the tool face, the cover and any sealing material of the opening. First multiple connection holes can be used. A vacuum system 445 is connected to the first connection hole (s). A second connection hole 450 is located on the cover (as shown in this example), or the opening 430 so that this connection hole accesses the volume defined by the tool body, the tool face, the cover and any sealing material of the opening. A resin tank 455, vented to the atmosphere, is connected to the second connection hole.

If the opening and the connection holes are sealed or otherwise closed, the composite forming materials on the tool face are therefore contained within a closed volume 460. This closed volume can be sealed essentially tightly when the surfaces of the tool body and the cover, and the opening between the tool body and the cover are sealed or otherwise impervious to the passage of gases.

In use, the composite reinforcement materials are placed on the tool face and the opening between the tool body and the cover is sealed except for the connection holes. The operation of the vacuum system removes the air from the closed volume and the composite reinforcement materials contained within the closed volume. The operation of the vacuum system also causes the cover to be pushed towards the outer limit of the composite reinforcement materials by the action of local atmospheric pressure. Then the cover presses these materials against the tool face. In addition, if the cover is made of a rigid material, the conformation of the cover influences the conformation of the surface (s) of the composite piece (s) adjacent to an inner surface of the cover.

The operation of the vacuum system also causes the resin in the resin tank to be transferred from the tank to the closed volume. Optionally, a pump can be used to aid in resin transfer. The resin in the closed volume then perfumes into the composite reinforcing material to result in the production of a composite forming material. The second connection hole is closed once a sufficient amount of resin has been transferred to form the desired composite composition with the reinforcing material at the closed volume.

Once the perfusion of the resin reinforcement material is finished, the composite material formation materials are then cured to produce a piece of composite material having the shape conferred by the tool face. Heating or heating of composite materials is preferred or required for some composite materials to cure. The tool and cover assembly can be placed in an autoclave to apply additional pressure to the cover and / or to heat the composite formation materials to cure. Resin transfer in an autoclave can also be implemented. Other devices such as an oven, and / or individual heating elements may be used to apply heat to the materials contained within the closed volume in order to cure the composite forming materials contained therein to result in the workpiece. composite material. If desired, the individual heating elements may be embedded within the tool body. Depending on the properties of the resin used to form the composite material, room or ambient temperature may be sufficient, for example, to cure the materials to form the composite piece.

As discussed above, heating will effect changes in the dimensions of all heated materials. The magnitudes of such dimensional changes depend on the CETs of the individual materials. In particular, the CET of the tool face and the resulting composite part are substantially similar or equivalent, as would be the case if the resulting composite part and the tool face material were CFC.

The skilled artisan can classify the tooling treated in this illustrative example as an example of VARTM (vacuum assisted resin transfer molding). Slight modifications in the teachings of this example would then produce the illustrative example of RTM (resin transfer molding). These modifications are the elimination of the vacuum system and the closed volume ventilation. Closed volume ventilation can be through the use of an open connection hole or by not sealing the opening between the cover and the tool body.

In RTM, composite reinforcement materials are placed on the tool face.

The resin in the resin tank is then transferred, usually by the action of a pump, from the tank to the closed ventilated volume. The resin in the closed volume then perfuses into the composite reinforcement material to result in the production of a composite forming material. The second connection hole is closed once enough resin has been transferred to the closed volume and / or reinforcing material.

Figure 5 illustrates a fifth exemplary embodiment of a system according to this invention.

Figure 5 illustrates a cross-sectional representation of a reusable tool comprising a tool body 500 comprised at least in part of carbon foam. This tool body is divided into two sections, an upper 500-A section and a lower 500-B section. Although not illustrated in this example, more than two sections could be used in a single tool body. The surfaces of these sections come into close contact with each other along a mutual surface, which will be called the dividing surface 505. A part of the dividing surface of each section is machined, contoured, molded or otherwise shaped to provide a tool face 510 of the desired dimensions. The tool faces of each section are placed on the dividing surfaces so that a volume 515 is defined which has the conformation and dimensions of the composite piece planned for production in the tool. Additionally, the tool faces are placed on the dividing surfaces so that the dividing surfaces of each section come into contact with each other around the perimeter of the tool faces. The contact area of the dividing surfaces can be sealed as desired or required with various materials including adhesive tape, sealing gasket material, insulator, seal and the like. In this example, the tool face of the upper tool section extends from 520-A to 520-B. The tool face of the lower tool section extends from 520-C to 520-D

For each section, a surface of the carbon foam incorporated in the tool body supports a tool face material 525. This tool face material forms the surface of the tool faces and preferably the dividing surface of each section. Preferably, this tool face material is a carbon fiber composite material. Alternatively, a surface of the carbon foam of the upper and lower tool body sections can serve as the tool faces and / or dividing surfaces. The cells of this carbon foam can be partially or completely filled. Release compounds and partition sheets may be used as desired and appropriate. These procedures can be used alone or in combination.

Axes connect the volume defined by the tool faces with the outside of the tool body. 530 ventilation shafts connect the uppermost section (s) of the volume with the atmosphere. This type of shaft (s) is formed in the most convenient way in the upper tool body. Another shaft (s) 535 is connected to a tank (s) 540 that contains a resin. This type of axis (s) is connected to the lower section (s) of the volume.

In use, composite reinforcement materials are placed in the volume defined by the tool faces. Resin is then introduced into the volume, usually by the action of a pump, from the bonded tank. The resin fills the volume and infiltrates the reinforcing materials. The introduction of the resin stops when the resin enters the axis (s) that connects the volume with the atmosphere.

The composite materials forming materials are then cured to produce a piece of composite material that has the shape conferred by the tool faces. Heating or heating of composite materials is preferred or required for some composite materials to cure. The heating can be carried out by using an autoclave, oven, individual heating elements and / or other similar heating devices. The individual heating elements may be external to, or internal to (ie, not embedded within), the tool body. As discussed above, heating will effect changes in the dimensions of all heated materials. The magnitudes of such dimensional changes depend on the CETs of the individual materials. Specifically, the CET of the tool face and the resulting composite part are similar or essentially identical, as would be the case if the resulting composite part and the tool face material were CFC.

Those skilled in the associated techniques can classify the tooling treated in this illustrative example as an example of RTM (resin transfer molding). Slight modifications in the teachings of this example would then produce the illustrative example of VARTM (vacuum assisted resin transfer molding). These modifications are the connection of the ventilation shaft (s) to a vacuum system instead of the atmosphere. It may also be necessary to more thoroughly seal the tool faces, the dividing surfaces and / or the contact area of the dividing surfaces so that they are impervious to gases.

Figure 6 illustrates a sixth exemplary embodiment of a system according to this invention.

Figure 6 illustrates a cross-sectional representation of a reusable tool comprising a tool body 600 comprised at least in part of carbon foam. A surface of the carbon foam incorporated in the tool body is contoured or otherwise shaped to give rise to a desired configuration to provide a tool face 605. In Figure 6, the tool face extends from 605-A to 605-B. The carbon foam cells that incorporate this tool face may be partially filled so that the tool face remains permeable to the passage of gases. Alternatively, the carbon foam supports a gas permeable tool face material. A section of the exposed surface of the tool face material is contoured or otherwise shaped to give rise to a desired configuration to provide a tool face. The surface area of the outer tool body, with the exception of the tool face and a connection zone 610, are sealed with a gas-impermeable material 615. A first connection hole 620 is fixed in the connection zone. This connection hole is connected to a vacuum system 625.

The surface 630 of the tool body immediately surrounding the tool face is equipped with two frames, an upper frame 635 and a lower frame 640. Each frame holds a gas-impermeable elastomeric membrane. The upper frame supports the upper membrane 645. The lower frame supports the lower membrane 650. The frames are of equivalent size and are stacked so that a first closed volume 655 is formed between the membranes. In addition, the stacked frames are placed on the surface of the tool body immediately surrounding the tool face so that a second closed volume 660 is formed between the tool face and the bottom membrane. These closed volumes can be sealed against the transfer of unwanted gas into and out of these volumes by applying shutters 665 between the frames and between the upper frame and the surface of the tool body immediately surrounding the tool face. The seals may include various materials including adhesive tape, sealing gasket material, insulator, seal and the like. A second connection hole 670 is located between the frames, or alternatively, in the upper membrane so that it provides communication between a second vacuum source 675 and the first closed volume.

In use, the composite material forming materials 680 are placed in the first closed volume. Operation of the vacuum system (s) removes air from the first closed volume and the second closed volume. It should be noted that the air removed from the second closed volume is drawn through the tool body to the first connection hole and from there to the vacuum system. The resulting volume in the first closed volume removes air from the composite forming materials. The resulting vacuum in the second closed volume causes the elastomeric membranes to flex so that the composite forming materials are pushed and placed against the tool face by the action of the ambient atmospheric pressure on the upper membrane.

Then the composite forming materials are cured to produce a piece of composite material that has the shape conferred by the tool face. Heating or heating of composite materials is preferred or required for some composite materials to cure. The tool can be placed in an autoclave to apply additional pressure to composite materials and to heat those materials to cure. Other devices such as an oven, and / or individual heating elements may be used to apply heat to the materials contained within the closed volume in order to cure the composite formation materials contained therein to result in the workpiece. composite material. If desired, the individual heating elements may be embedded within the tool body. Depending on the properties of the resin used to form the composite material, room or ambient temperature may be sufficient, for example, to cure the materials to form the composite piece.

As discussed above, heating will effect changes in the dimensions of all heated materials. The magnitudes of such dimensional changes depend on the CETs of the individual materials. Specifically, the CET of the tool face and the resulting composite part are similar or essentially identical, as would be the case if the resulting composite part and the tool face material were CFC.

Figure 7 illustrates an seventh exemplary embodiment of a system according to this invention.

Figure 7 illustrates a three-dimensional representation of a first half of a reusable tool body comprised at least in part of carbon foam. This part of the tool body 700 consists of carbon foam having a dividing surface 705 in which a conformation 710 is machined, shaped, molded or otherwise formed. In this representation, that conformation is a hemisphere. A channel 715 is also machined, shaped, molded or otherwise formed on the dividing surface of the carbon foam. This channel crosses the dividing surface of the tool body part from the conformation to an outer edge of that surface.

The second half of the reusable tool body (not shown) has a dividing surface. This second half may also have a channel and a mechanized, shaped, molded or otherwise formed conformation on the dividing surface. This channel and the conformation of the second half may reflect those of the first half. The dividing surface of the second half can be constructed such that it is a dimensional mirror image of the dividing surface of the first half. As such, a narrow fit can be obtained when the dividing surfaces of the first and second half are joined together. In particular, the second half can be constructed so that a channel, if present, crosses the surface to an edge that is essentially the mirror image of the edge that comes into contact with the channel of the first half.

The shape conferred to the halves of the tool body by the channel (s) and the conformation / conformations constitutes a tool face. These tool faces can have any shape that provides that a line can be drawn from a plane parallel to the dividing surface to each part of the tool face. The tool face material is layered on the carbon foam to provide a tool face. These tool face materials may be any of those known in the associated techniques including carbon fiber composites.

In use, the two halves of the tool body are joined together on the dividing faces. Fixing bolts or control marks can be used to ensure proper alignment of the two halves. Various methods can be used to maintain the contact of the dividing surfaces. Such procedures include, but are not limited to, fixing, screwing and fastening with strapping. Composite forming materials (such as resins containing short fiber reinforcements or particulate material) can then be poured into the channel (s). Composite forming materials are then transported through the channel to the volume defined by the tool face conformation. Alternatively, the volume defined by the tool face conformation may contain a composite reinforcement material, such as fibers. The resin introduced into the channel would then prefund in this composite reinforcing material to result in a composite forming material. If desired, the tool body can be rotated and / or rotated so that the composite forming material uniformly covers the tool face.

It is also possible to fill the shapes in the halves of the tool body with composite reinforcement materials before joining the halves in the dividing faces. Once joined, resin can be poured into the channel (s). The resin is then transported by gravity to the volume defined by the tool face conformation. Alternatively, the resin can be pumped into the volume defined by the tool face conformation. In this volume, the resin perfuses into the reinforcing materials resulting in the formation of a composite material forming material.

The composite material formation materials are then cured to produce a piece of composite material that has the shape conferred by the tool face. Heating or heating of composite materials is preferred or required for some composite materials to cure. The tool can be placed in an autoclave to apply additional pressure to composite materials and to heat those materials to cure. Other devices such as an oven, and / or individual heating elements, can be used to apply heat to the materials contained within the tool volume in order to cure the composite formation materials contained therein to result in the piece of composite material. If desired, the individual heating elements may be embedded within the tool body. Depending on the properties of the resin used to form the composite material, room or ambient temperature may be sufficient, for example, to cure the materials to form the composite piece.

Figures 8A, 8B and 8C illustrate an eighth exemplary embodiment of a system according to this invention.

Figures 8A, 8B and 8C illustrate the preparation of a reusable tool body of a composite tool according to the present invention. Referring to Figure 8A, a block 800 of carbon foam is illustrated. The carbon foam block will comprise at least a part of a tool body. The carbon foam block can be formed with any desired geometry. Additionally, this carbon foam block may be composed of two or more individual carbon foam blocks. In this illustrative example, three blocks 802, 804 and 806 of carbon foam are bonded together with an adhesive material, or the like, in order to form the block 800 of carbon foam of the tool body. The adhesive material used to bond the individual carbon foam blocks can be, for example, an adhesive film, a resin and the like. More specifically, commercially available adhesive materials can be used. For example, Graphi Bond 551, Expando and / or refractory cement can be used. In particular, the various 802, 804 and 806 carbon foam blocks are prepared so that they have a substantially similar or identical CET. Alternatively, a single block of carbon foam can be used to form the tool body 800.

A surface of the carbon foam block 800 is then formed to give a desired geometry 810. For example, a surface 812 of the carbon foam block 800 is machined to give a predetermined geometry. Normally, the dimensions of the shaped surface of the carbon block conform to the dimensions of a tool face material, in this example a formed laminated material, which will ultimately define the tool face. That is, the shaping can be performed in a slightly larger profile than if the tool face material was not planned for use.

Referring to Figure 8B, after forming, a resin laminated material 814 and reinforcement materials are arranged on the formed surface 812 of the carbon foam block 800. The laminated material will constitute a tool face material. The materials used to form the laminated material are selected so that the CET of the resulting cured laminate and the carbon foam block 800 are identical, specifically equivalent. The surface of the laminated material 814, opposite the carbon foam block, will serve as the tool face of the tool body once the curing of the laminated material is finished. Therefore, the laminated material 814 is formed to provide a surface that has the dimensions of the desired tool face. In this embodiment of the present invention, the laminated material 814 is a carbon fiber composite. In other embodiments of the present invention, any of the tool face materials discussed above may be replaced by the laminated material provided that the CET of the tool face material and the carbon foam tool body are equivalent.

The laminated material 814 is covered with a cover 816 connected to a vacuum system (not shown) so that the pressure in volume 815 between the cover and the laminated material 814 can be reduced. It may be necessary to seal the cover 816 with the laminated material 814 and / or the tool body 800. In this way, the laminated material is compressed against the formed surface 812 of the carbon foam block 800 by the action of the ambient atmospheric pressure located on the roof. The cover 816 can be a silicon membrane, an elastomer bag and the like. The laminated material is then cured.

Referring to Figure 8C, the cured laminated material 814 is temporarily removed from the carbon foam block 800. An adhesion paste 816 is applied on the surface of the carbon foam block 800 in order to bond the contact surface between the carbon foam block 800 and the laminated material 814. The cured laminated material 814 is then replaced on the carbon foam block. Once the joint is complete, the outer surface 818 of the laminated material 814 is optionally machined and / or finished to give predetermined dimensions and geometry as necessary. The assembly of the carbonaceous foam block 800 and the cured laminated material 814 now constitutes a tool body with the tool face being the outer surface of the laminated material.

As discussed above, the tool face materials can be replaced by the material 814 laminated in the tooling of the present invention. For example, an arc sprayed metal can be applied to the surface of the carbon foam block 800 to act as a tool face material and thus provide a tool face. A tool face material of this type can be machined or otherwise formed subsequently to precisely give the desired geometry by conventional metal fabrication techniques. Additionally, a resin or other tool face material may be applied on the carbon foam block 800 instead of the laminated material. In this configuration, the resin is applied to the surface 812 of the carbon foam block 800 and allowed to cure. The resin is then ground or otherwise shaped to give the desired geometry to obtain a tool face ready for use in the production of composite parts.

If desired, plot lines, cross-hatch, patterns and the like can be incorporated into the tool faces provided by any of the above procedures. These patterns, and the like, will eventually be incorporated into the tooling pieces formed with the tooling body.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. Therefore, it is intended that the present invention cover the modifications and variations of this invention provided that they are within the scope of the appended claims and their equivalents.

Claims (17)

1. Tool for the production of at least one piece of composite material, the tool comprising a body (400) of carbon foam tool and supporting said body (400) of carbon foam tool a tool face material (405), characterized in that the coefficient of thermal expansion of the tool face material (405) and the carbon foam tool body (400) are equivalent.

2.

Tool according to claim 1, wherein at least a part of the carbon foam cells are at least partially filled with a filler material.

3.

Tool according to claim 2, wherein the filler material is at least one of a cured resin, a pitch, a cured moldable ceramic material, a carbonized resin or a carbonized pitch.

Four.

Tool according to claim 1, wherein the coefficient of thermal expansion of the face

Tool (410) is substantially similar to the coefficient of thermal expansion of a piece of composite material produced on the tool face (410).

5.

Tool according to claim 1, wherein the tool face material (405) is selected from the group consisting of metals and ceramic materials.

6.

Tool according to claim 1, wherein the tool face material (405) is selected from the group consisting of a cured resin, a fiber composite material, a carbon fiber composite material, a particulate composite material, INVAR® , silicon carbide and zircona ceramic materials.

7.

Tool according to claim 1, wherein the carbon foam is derived at least in part from pitch, coal or a carbon derivative.

8.

Tool according to claim 1, wherein the tool body (400) is shaped like a mandrel.

9.

Tool according to claim 1, further comprising a cover (420) placed at least partially on the tool face (410) and enclosing at least a part of the tool face (410).

10.

Tool according to claim 9, further comprising a resin reservoir connection hole (440, 450) in vacuum communication with the enclosed part of the tool face, wherein the reservoir connection hole (440, 450) Resin is adapted to be connected to a resin reservoir system (455) and provides resin transfer from the resin reservoir system (450) to the enclosed part of the tool face when a vacuum is created in the enclosed portion of The tool face.

eleven.

Procedure for producing at least one piece of composite material, comprising the steps of:

providing a carbon foam tool body (400) having a tool face (410) and said tool face (410) comprises a tool face material (405); place composite material forming material on the tool face; Y curing the composite material forming material thereby producing the composite part, characterized in that the thermal expansion coefficient of the tool face material (405), the carbon foam tool body (400) and the material of Composite formation are equivalent.

12.

Process according to claim 11, wherein the composite forming material is a mixture of a resin and at least one selected from the group consisting of a particulate reinforcement material and a fibrous reinforcement material.

13.

Method according to claim 11, further comprising the step of placing a dividing film between the composite materials and the tool face.

14.

Method according to claim 11, further comprising the step of coating at least a part of the tool face (410) with a release agent before contacting the tool face (410) with the forming material (425) of composite material.

fifteen.

Method according to claim 11, wherein the tool face material (405) is selected from the group consisting of metals and ceramic materials.

16.

Method according to claim 11, wherein the tool face material (405) is selected from the group consisting of a cured resin, a fiber composite, a

5 carbon fiber composite material, a particulate composite material, INVAR®, silicon carbide, and INVAR® zircona ceramic materials, silicon carbide and zircona ceramic materials. 17. The method of claim 11, wherein the tool further comprises a cover (420) placed on at least a part of the tool face (410) and enclosing 10 at least a part of the tool face, and in which the composite material (425) is placed on the enclosed part of the tool face, and further comprising the step of producing a vacuum within the enclosed part of the tool face.