Multi-segment tool and method for composite formation

RELATED APPLICATIONS

0001This application is a reissue application of U.S. Pat. No. 8,394,315, issued on Mar. 12, 2013 (FKA U.S. Ser. No. 13/217,709, filed on Aug. 25, 2011), entitled, “MULTI-SEGMENT TOOL AND METHOD FOR COMPOSITE FORMATION.” The '315 patent is a divisional of U.S. application Ser. No. 12/263,915 filed Nov. 3, 2008, the content of which isentitled “MULTI-SEGMENT TOOL AND METHOD FOR COMPOSITE FORMATION,” which issued as U.S. Pat. No. 8,025,499 on Sep. 27, 2011. Both of the aforementioned patents are incorporated herein by reference in itstheir entirety.

FIELD OF THE INVENTION

0002The invention is directed to a multi-segment tool and method for vacuum forming a composite part in general, and more specifically a tool and method relating to composite formation of an aircraft nacelle and related parts.

BACKGROUND

0003Aircraft structures have many components that have complex shapes with multiple curvatures. For example, various complex shapes are found in aircraft nacelle and pylon systems, thrust reversers and rocket thruster chambers, among others. Several methods are known to form complex shapes. For thermoplastic and thermoset polymers, multiple tools can be used in injection and compression molding operations to form complex shapes. Metal forming techniques have used casting plugs to facilitate the formation of metallic rocket thrust chambers having hour-glass configurations. These methods, however, are not readily adaptable for forming complex parts using vacuum bag composite techniques.

0004Vacuum bag forming is a method of composite fabrication that can be used to form complex shapes using multiple tools. In vacuum bag forming, a vacuum pulls a preform around the contours of a tool. Where multiple tools are used to form composite parts, there must be sufficient vacuum sealing between the tools. Vacuum integrity and proper tool alignment is important to achieve desired end-product form and properties. Because the vacuum pulls a preform into every contour, seam defects result if there is less than precise alignment between the tools. Mechanical fasteners such as bolts and the like have attempted to ensure alignment among multiple tools. Such systems, however, can be cumbersome, costly and inadequate to minimize seam defects. In terms of vacuum integrity, gaskets, o-rings and similar devices have been used to improve vacuum integrity between adjacent tools. These attempts often result in less than full vacuum integrity leading to possible product defects, poor resin cure and poor resin-to-matrix migration, contributing to potential product deficiencies. In response, some have attempted to use multiple vacuum barriers to ensure vacuum integrity, but such solutions increase processing complexity and cost.

0005A need has arisen for the ability to form multiple curvature composites, either integrally formed or formed with minimal sub-parts, where the seams are minimized, sufficient vacuum integrity is achieved and misalignment of tools is reduced. Further, there is a need for an efficient method of forming complex shapes while providing flexibility to accommodate changing design constraints.

BRIEF DESCRIPTION OF DRAWINGS

0006<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> show a first tool of a multi-segment tool according to a first embodiment.

0007<figref idref="DRAWINGS">FIGS. 2A, 2B and 2C</figref> show a second tool of a multi-segment tool.

0008<figref idref="DRAWINGS">FIG. 3</figref> shows a multi-segment tool.

0009<figref idref="DRAWINGS">FIGS. 4A and 4B</figref> show sections of the multi-segment tool taken along lines <b>4</b>-<b>4</b> of <figref idref="DRAWINGS">FIG. 3</figref>.

0010<figref idref="DRAWINGS">FIG. 5</figref> is a side view of a multi-segment tool with a composite placed thereon.

0011<figref idref="DRAWINGS">FIG. 6</figref> is a side view of a multi-segment tool and composite encased in an illustrative vacuum barrier.

0012<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> show removal of the second tool and composite part from the first tool.

0013<figref idref="DRAWINGS">FIG. 8</figref> is a top perspective view of a second embodiment of a first tool of a multi-segment tool.

0014<figref idref="DRAWINGS">FIG. 9</figref> is a top perspective view of a first and second tool.

0015<figref idref="DRAWINGS">FIGS. 10A and 10B</figref> show alignment features of a multi-segment tool.

0016<figref idref="DRAWINGS">FIG. 11</figref> is a top perspective assembly view of a first and second tool with a third tool being added.

0017<figref idref="DRAWINGS">FIG. 12A</figref> is an exploded perspective view of a portion of the bottom of the third tool.

0018<figref idref="DRAWINGS">FIG. 12B</figref> is an exploded perspective view of a portion of the first tool and of the third tool.

0019<figref idref="DRAWINGS">FIG. 13</figref> shows a multi-segment tool on a frame.

0020<figref idref="DRAWINGS">FIG. 14</figref> is a cut away close-up of a multi-segment tool with one fairing removed.

0021<figref idref="DRAWINGS">FIG. 15</figref> shows a multi-segment tool with a composite and illustrative vacuum barrier

0022<figref idref="DRAWINGS">FIG. 16</figref> shows a perspective assembly schematic of a multi-segment tool and composite.

SUMMARY

0023A multi-segment tool for vacuum forming a composite part can include a first tool having a first surface and a second surface. A second tool can have an opening. The second tool can be capable of receiving the first tool through the opening. A second tool can be further capable of being positioned on the first tool in a location other than the first surface or second surface. The first tool can receive at least a portion of a preform composite. The second tool can receive at least a portion of the preform composite. The first tool can have a vacuum barrier attached to the first surface and to the second surface, wherein a vacuum barrier encapsulates the preform composite and the second tool.

0024A tooling system for vacuum forming a composite part can include a first tool having a core and a base with the core extending upwards from the base. A second tool can be positioned upon the core in such a way that a portion of the core extends above the second tool. The tooling system can further include a composite formed on the first tool and the second tool, the composite having a complex shape. A vacuum barrier can be pressure sealed to the base and to the portion of the core that extends above the second tool. The vacuum barrier can be capable of forming a pressure seal that includes the composite, the first tool and the second tool.

0025A method of forming a composite part can include providing a first tool and positioning a second tool on a first tool. The second tool can have an opening capable of receiving the first tool through the opening. A method can include applying a composite preform on at least a portion of the second tool. A method can include vacuum sealing the composite preform by securing a vacuum barrier to the first tool while the preform and second tool can be encapsulated within a vacuum barrier. A method can further include curing the preform to form a composite part.

0026The foregoing and other features, aspects and advantages of the invention will be apparent from a reading of the following detailed description together with the accompanying drawings, which are described below.

Description

0027Certain exemplary embodiments of the present invention are described below and illustrated in the accompanying Figures. The embodiments described are only for purposes of illustrating embodiments of the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications and improvements of the described embodiments, will occur to those of skill in the art, and all such alternate embodiments, modifications and improvements are within the scope of the present invention.

0028The tool and method in general comprises two or more tools that can mate with one another to form a desired mold profile. Composite materials are then applied upon or laid up on the tools. The composite can be then encased within a vacuum barrier or bag, which can be sealed around the composite and secured to surfaces of one of the tools. After curing, the parts can be selectively removed, resulting in a composite structure having a complex shape. In a preferred embodiment, a 360 degree complex shape can be produced for use as, for example, a one-piece inner barrel of an aircraft engine nacelle.

0029More specifically, a first embodiment for a tool or system for vacuum forming a composite part is shown in <figref idref="DRAWINGS">FIGS. 1 through 7</figref>. <figref idref="DRAWINGS">FIG. 1A</figref> shows a first tool <b>30</b>. First tool <b>30</b> can have a top portion <b>32</b> and a bottom portion <b>36</b>. Top portion <b>32</b> has a top edge <b>34</b>, and bottom portion <b>36</b> has a bottom edge <b>38</b>. In the embodiment shown, both top edge <b>34</b> and bottom edge <b>38</b> are circular and form planes that are substantially in parallel orientation with one another. First tool <b>30</b> can be a 360 degree tool as shown. A 360 degree tool refers to a tool that can be used to mold 3-dimensional parts that have some type of void or internal open cavity therewithin. Such parts in a preferred embodiment are formed partially or completely around the tool, thereby creating a partial or extended annular opening in the part. For example, 360 degree tools can be used in the aircraft industry to produce nacelles, pylon systems, thrust reversers, rocket thruster chambers, etc. In a preferred embodiment, the 360 degree tool has an uppermost portion that has a smaller cross sectional area than portions elsewhere on the tool, thereby permitting the part to be removed upwardly along an axis substantially aligned with the annular opening formed by the tool. Thus, a 360 degree tool can be frusto-cone or frusto-pyramid to facilitate creation of such annual parts.

0030First tool <b>30</b> can have outer shape profiles designed as necessary to conform to the desired composite part and/or to mate with additional tools. Bottom portion <b>36</b> can have bottom side <b>37</b> that extends upward and inwardly from bottom edge <b>38</b>. Similarly, top portion <b>32</b> can have an alignment bevel <b>33</b> that also slopes upward and inwardly towards top edge <b>34</b>. Alignment bevel <b>33</b> can also facilitate tool alignment. To facilitate removal of tool(s) and/or composite part(s), alignment bevel <b>33</b> and bottom side <b>37</b> preferably have right (90°) or acute (less than 90°) angles θ₁, θ₂, respectively, (as shown in <figref idref="DRAWINGS">FIG. 1A</figref>) measured with respect to a line <b>31</b> orthogonal to a plane defined by bottom edge <b>38</b>.

0031First tool <b>30</b> has an alignment ridge <b>35</b> as shown, for example, in <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>. Alignment ridge <b>35</b> in this embodiment can be a lip, machined step, indentation or projection on the first tool <b>30</b>. More than one alignment ridge <b>35</b> can be present on first tool <b>30</b>, to facilitate positioning the first tool <b>30</b> with a mating tool having a complex profile, or with additional tools. Alignment ridge <b>35</b> is formed circumferentially around first tool <b>30</b>, and in parallel configuration to the plane formed by bottom edge <b>38</b>. In alternate embodiments, alignment ridge <b>35</b> can form any angle with respect to the plane formed by bottom edge <b>38</b>. Also, alignment ridge <b>35</b> can be any shape as determined by the needs of mating alignment of additional tools. A clocking pin (not shown) can be located on alignment ridge <b>35</b> to facilitate the location and alignment of additional tools.

0032<figref idref="DRAWINGS">FIG. 1B</figref> is a top view of first tool <b>30</b>, showing the bottom edge <b>38</b>, bottom side <b>37</b>, alignment ridge <b>35</b>, alignment bevel <b>33</b> and top edge <b>34</b>. Interior space <b>39</b> facilitates cooling and access to mechanical and vacuum components.

0033<figref idref="DRAWINGS">FIGS. 2A, 2B and 2C</figref> show an embodiment of a second tool <b>40</b>, which is capable of mating alignment with first tool <b>30</b>. Second tool <b>40</b> has a top <b>42</b>, bottom <b>44</b> and a second tool side <b>48</b> extending therebetween.

0034<figref idref="DRAWINGS">FIG. 2B</figref> shows a cross section, taken along lines <b>2</b>B-<b>2</b>B of <figref idref="DRAWINGS">FIG. 2A</figref>. Top <b>42</b>, bottom <b>44</b> and second tool side <b>48</b> are shown. Side <b>48</b> has a thickness T₁at the top and a thickness T₂at the bottom. Side interior wall <b>47</b> can be configured to fit atop the first tool <b>30</b> and be positioned adjacent to alignment bevel <b>33</b>. To accomplish this, wall <b>47</b> can be oriented at angle θ₂to sit flush against alignment bevel <b>33</b>, which is the same angle θ₂orientation of the alignment bevel <b>33</b> of the first tool top portion <b>32</b> (see <figref idref="DRAWINGS">FIG. 1A</figref>). Interior edge <b>43</b> located at the top <b>42</b> of second tool <b>40</b> defines an opening, or an interior cross-sectional area <b>45</b>, as shown in <figref idref="DRAWINGS">FIG. 2C</figref>.

0035<figref idref="DRAWINGS">FIG. 2C</figref> is a top view of second tool <b>40</b> shown in <figref idref="DRAWINGS">FIG. 2A</figref>, showing the cross-sectional area <b>45</b> defined by the interior edge <b>43</b>, and the top thickness T₁. This interior cross-sectional area <b>45</b> allows the second tool <b>40</b> to fit over the top portion <b>32</b> of the first tool <b>30</b>.

0036As shown in <figref idref="DRAWINGS">FIGS. 2A and 2B</figref>, an outer wall <b>49</b> of side <b>48</b> of the second tool <b>40</b> generally extends outwards from the bottom <b>44</b>, in an inverted frusto-cone shape. Other examples of a shape of a second tool include an inverted frusto pyramid, where the top perimeter also is larger than the bottom perimeter. The second tool <b>40</b> can be integrally formed, such as shown in <figref idref="DRAWINGS">FIGS. 2A, 2B and 2C</figref>, or can comprise several discrete segments (not shown) disposed radially or circumferentially to form a 360 degree part.

0037As shown in <figref idref="DRAWINGS">FIGS. 3, 4A and 4B</figref>, the second tool <b>40</b> can be lowered onto and placed atop first tool <b>30</b>. When the first tool <b>30</b> and second tool <b>40</b> are assembled, a multi-segment tool <b>10</b> is formed. Multi-segment tool <b>10</b> has an outer shape <b>12</b> that will become the form on which a composite is laid, as discussed below. The embodiments shown reflect a configuration whereby top edge <b>34</b> of first tool <b>30</b> extends above the top <b>42</b> of second tool <b>40</b>.

0038<figref idref="DRAWINGS">FIG. 4A</figref> is a cross-section taken along lines <b>4</b>-<b>4</b> of <figref idref="DRAWINGS">FIG. 3</figref>. Second tool <b>40</b> is shown placed upon the top portion <b>32</b> of the first tool <b>30</b>. <figref idref="DRAWINGS">FIG. 4B</figref> is an exploded view of the circled area shown in <figref idref="DRAWINGS">FIG. 4A</figref>, and shows the interior wall <b>47</b> of second tool <b>40</b> adjacent to the alignment bevel <b>33</b> of the first tool <b>30</b>. The bottom <b>44</b>, having a thickness T₂, of side <b>48</b> of the second tool <b>40</b> is positioned atop the alignment ridge <b>35</b> of the first tool <b>30</b>. The second tool <b>40</b> meets the alignment ridge <b>35</b> at joint <b>15</b>.

0039First and second tools <b>30</b>, <b>40</b> can be formed from a variety of non-metallic materials such as composites or metallic alloys such as, for example, aluminum, nickel, iron, steel or a substantially inexpansible alloy, such as Invar® nickel steel alloy, as needed. Selection of a tool material typically is based on forming method, composite part tolerances, number of curing and/or heating cycles, coefficient of thermal expansion of the tooling material, desired or required surface condition of the composite part, composite constituents, and cost, as is generally known in the art. In a preferred embodiment, the tools are formed of Invar® alloy.

0040<figref idref="DRAWINGS">FIGS. 5 through 7B</figref> show the addition of a composite part <b>16</b> to multi-segment tool <b>10</b>. In <figref idref="DRAWINGS">FIG. 5</figref>, composite part <b>16</b> can be laid upon the multi-segment tool <b>10</b> by known methods, including for example, laying together individual plies of a pre-impregnated composite to create the final laminated structure. In a preferred embodiment, the composite is prepared by hand lay up of pre-impregnated plies of a graphite fabric. The composite part <b>16</b> can be a complex shape due to the geometries of the first part <b>30</b> and second part <b>40</b>.

0041The composite part <b>16</b>, which sometimes is called a preform prior to curing, is typically comprised of a reinforcement and a matrix. Reinforcements can be carbon, aramid fibers, para-aramid fibers, glass fibers, silicon carbide fibers, high strength polyethylene or other composite fiber materials as is known in the art. The reinforcement material can be short or long fibers, woven, laid-up reinforcements, laminates or any combination thereof. The matrix can be a thermoset or thermoplastic polymeric resin such as polyester, vinyl ester, epoxy, phenolic, polyimide, polyamide, polypropylene, PEEK or baselimide. In a preferred embodiment, the reinforcement is graphite and the matrix is epoxy.

0042<figref idref="DRAWINGS">FIG. 6</figref> illustrates the addition of a vacuum barrier <b>20</b> that encases the composite part <b>16</b> and portions of the multi-segment tool <b>10</b>. Vacuum barrier <b>20</b> can be secured and sealed to bottom portion <b>36</b> and top portion <b>32</b> of first tool <b>30</b>, using securing methods known to those of skill in the art. In a preferred embodiment, the vacuum barrier <b>20</b> is sealed by a sealant tape. Sealed in this manner, the vacuum barrier <b>20</b> encases the composite part <b>16</b> and the second tool <b>40</b>.

0043Vacuum barrier <b>20</b> can be a flexible polymeric material, or other material as is known in the art, sufficient to withstand temperatures and pressures encountered with vacuum bag composite curing. A vacuum is drawn from the space between vacuum barrier <b>20</b> and multi-segment tool <b>10</b> using a vacuum source (not shown) such as a compressor or venturi pump as is known in the art. Pressure approaching approximately one atmosphere forces composite part <b>16</b> against the outer profile <b>12</b> of multi-segment tool <b>10</b>.

0044After securing the vacuum barrier <b>20</b> and achieving the desired pressure conditions, the composite part <b>16</b> is then cured. Cure, or curing, as used herein, refers to the process that results in cross-linking or solidification of a matrix and reinforcement. Curing can occur in pressurized vessels at elevated temperatures in devices such as an autoclave, as is known in the art. In an alternate embodiment, curing can occur at ambient temperature and/or atmospheric pressures. Multiple cures cycles can be used as the need may arise. For example, a preform can undergo a first and second cure to form composite part <b>16</b>. In one example using the tool described herein, a woven carbon fiber-epoxy composite part <b>16</b> was exposed to about 350° F. simultaneously with pressures ranging between about 35 psi to about 100 psi, preferably from about 70 to 80 psi, for about 120 minutes inside an autoclave. The particular temperature-pressure-time variable can be adjusted according to the particular reinforcement and matrix combination used in the preform, as is known in the art.

0045<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> show disassembly following cure and removal of vacuum barrier <b>20</b>. The second tool <b>40</b> can be first lifted or axially removed from the first tool <b>30</b> as shown in <figref idref="DRAWINGS">FIG. 7A</figref>. As shown in <figref idref="DRAWINGS">FIG. 7B</figref>, composite part <b>16</b>, having a complex shape, can then be removed axially from the first tool <b>30</b>.

0046A second embodiment of a tool or system for forming a composite part is shown in <figref idref="DRAWINGS">FIGS. 8 through 16</figref>.

0047Referring to <figref idref="DRAWINGS">FIG. 8</figref>, first tool <b>130</b> comprises a core <b>131</b> shown sitting atop a base <b>139</b>. Core <b>131</b> comprises top portion <b>132</b> and middle portion <b>136</b>. A ridge <b>135</b> is located between the top portion <b>132</b> and middle portion <b>136</b>. Core <b>131</b> can be positioned off-center of first tool base <b>139</b> as shown. Such an off-center placement allows for support for a non-concentric second tool <b>140</b>. In alternate embodiments, core <b>131</b> can be centered on first tool base <b>139</b> to support concentric second and third tools <b>140</b> and <b>160</b>. Alignment guides <b>154</b> can be located on the middle portion <b>136</b> of the core <b>131</b>. Guides <b>154</b> can be located intermittently in relation to each other around middle portion <b>136</b>. Preferably four (4) guides are used, and are parallel to one another and positioned circumferentially around the middle portion <b>136</b>. Although the top portion <b>132</b> of first tool <b>130</b> can be a cylinder as shown, top portion <b>132</b> can also slope inwards in a truncated conical shape (not shown). The open inner volume <b>170</b> of first tool <b>130</b> helps provide air circulation and minimize tool heat-up during subsequent curing. The base <b>139</b> has a top surface <b>151</b>.

0048<figref idref="DRAWINGS">FIG. 9</figref> shows the addition of a second tool <b>140</b> and a transport frame <b>118</b>. Second tool <b>140</b> can be positioned atop top surface <b>151</b> (not shown in <figref idref="DRAWINGS">FIG. 9</figref>) of first tool <b>130</b>. As shown also in <figref idref="DRAWINGS">FIG. 10A</figref>, recess <b>157</b> on the interior side of the second tool <b>140</b> can cooperate with guides <b>154</b> to facilitate positioning and alignment of the second tool <b>140</b> over first tool <b>130</b>. So positioned, supporting core <b>131</b> extends up through the second tool <b>140</b> leaving guides <b>154</b> partially exposed and ready to receive additional tools. Transport frame <b>118</b> can support and transport the assembled multi-segment tool as needed. Transport frame <b>118</b> can be steel or other metallic alloys.

0049Second tool <b>140</b> has a top edge <b>142</b> and bottom edge <b>144</b>. Bottom edge <b>144</b> is generally circular and planar. As shown, top edge <b>142</b> also is shown generally non-parallel to the plane formed by bottom edge <b>144</b>. The use of such a non-parallel interface, also called a spline form split line, can assist in removal of the composite from the tool following curing. In practice, various non-parallel interfaces can be used, but preferably the angle between the interfaces will be greater than about five degrees. Bottom profile <b>145</b> defines the surface to which a preform will later be partially applied, as discussed below.

0050<figref idref="DRAWINGS">FIGS. 10A and 10B</figref> show details relating to a guide <b>154</b> and recess <b>157</b>. Tongue <b>153</b> of guide <b>154</b> fits within recess <b>157</b> of the second tool <b>140</b> and assists in guiding and aligning the second tool <b>140</b> on to first tool <b>130</b>. Notches <b>155</b> permit clearance for members <b>166</b> (shown in <figref idref="DRAWINGS">FIG. 12B</figref>) of third tool through ridge <b>135</b>. A first index shoe <b>152</b>, as shown in <figref idref="DRAWINGS">FIG. 10B</figref>, is located on the interior of the second tool <b>140</b> and facilitates alignment by receiving a second index shoe <b>156</b> of third tool <b>160</b> (shown on housing <b>163</b> in <figref idref="DRAWINGS">FIG. 12A</figref>). First and second index shoes <b>152</b> and <b>156</b> can help the second and third tools <b>140</b> and <b>160</b> form a smooth joint therebetween and limit deviation between the two tools. In a preferred embodiment, index shoe <b>152</b> has a recess into which projection from index shoe <b>156</b> fits.

0051<figref idref="DRAWINGS">FIG. 11</figref> shows the addition of a third tool <b>160</b>, ready to be lowered and positioned upon first tool <b>130</b> and into contact with the second tool <b>140</b> to form a multi-segment tool. Third tool <b>160</b> comprises a station datum plane <b>168</b>, housing <b>163</b> and upper profile <b>165</b>. The station datum plane <b>168</b> allows for the planar reference for coordination and fit between the tools. Station datum plane <b>168</b> can also allow for the verification of compliance with the desired contour tolerances. Station datum plane <b>168</b> also can provide support for fairings <b>126</b> (as shown in <figref idref="DRAWINGS">FIG. 13</figref>). A bottom edge <b>164</b> of upper profile <b>165</b> cooperates and mates with top edge <b>142</b> and lower profile <b>145</b> of second tool <b>140</b>. An inner opening <b>167</b> of third tool <b>160</b> receives first tool <b>130</b>. The housing <b>163</b> can have an interior lip (not shown) that cooperates and rests upon ridge <b>135</b>. At the bottom of the housing <b>163</b>, feet <b>169</b> (also shown in <figref idref="DRAWINGS">FIG. 12A</figref>) allow the tool to be placed on a hard surface without damage to the tool when not in use.

0052<figref idref="DRAWINGS">FIGS. 12A and 12B</figref> show hardware useful for aligning first, second and third tools <b>130</b>, <b>140</b>, and <b>160</b>. A second index shoe <b>156</b> can be positioned on housing <b>163</b>. When installed, the second index shoe <b>156</b> is aligned with the first index shoe <b>152</b> on second tool <b>140</b> (as shown in <figref idref="DRAWINGS">FIG. 10B</figref>). As discussed above, the index shoes can axially engage through a tongue and groove or other suitable mechanical, electronic or magnetic linkage. Preferably, four pairs of index shoe pairs are located circumferentially on the third and second tools <b>160</b> and <b>140</b>. The guides <b>154</b> (shown in <figref idref="DRAWINGS">FIG. 12B</figref>) of first tool <b>130</b> cooperate with alignment members <b>166</b> located on housing <b>163</b> of third tool <b>160</b>. Alignment members <b>166</b> can provide a close tolerance radial index with guides <b>154</b> as shown in <figref idref="DRAWINGS">FIG. 12B</figref>. Thus, alignment members <b>166</b> can align and index first tool <b>130</b> and third tool <b>160</b>. Index shoes <b>152</b> and <b>156</b> can align and index second tool <b>140</b> and third tool <b>160</b>.

0053<figref idref="DRAWINGS">FIG. 13</figref> shows an assembled multi-segment tool <b>110</b> also having fairings <b>126</b>. Preferably four (4) fairings <b>126</b> can be positioned on top of third tool <b>160</b> and around the top portion <b>132</b> of the first tool <b>130</b>. The fairings <b>126</b> can be formed from a lightweight fiberglass material. Other composites, metals and cured plastics capable of withstanding elevated temperatures can also be used. For example, light weight metallic alloys, such as aluminum and the like, can form fairings <b>126</b>. Fairings <b>126</b> cover mechanical fasteners and lifting hardware or other high profile gaps on the station datum plane <b>168</b> (as shown in <figref idref="DRAWINGS">FIG. 11</figref>) and help prevent bag pinch around sharp objects present on the top of third tool <b>160</b>. Casters <b>182</b> attached to the transport frame <b>118</b> aid in movement of the multi-segment tool.

0054In the assembled condition, multi-segment tool <b>110</b> comprises first tool <b>130</b>, second tool <b>140</b> and third tool <b>160</b>, assembled together. Lower profile <b>145</b> is mated to upper profile <b>165</b>, and together form a surface to which a composite preform can be placed.

0055<figref idref="DRAWINGS">FIG. 14</figref> shows an exploded and partially disassembled view of the third tool <b>160</b>, station datum plane <b>168</b> and fairings <b>126</b>. Various mechanical fasteners and lifting hardware <b>169</b> on third tool <b>160</b> facilitate transport and positioning of third tool <b>160</b> around the top portion <b>132</b> of the first tool <b>130</b> and onto second tool <b>140</b>. As shown, the top portion <b>132</b> extends above the third tool <b>160</b>, and provides a surface to which a vacuum bag can be attached as discussed below.

0056<figref idref="DRAWINGS">FIG. 15</figref> shows the multi-segment tool <b>110</b> after a composite part <b>216</b> and a vacuum barrier <b>220</b> has been applied thereto. The composite part can be integrally formed in 360° or in portions thereof. As stated above, the composite may be laid upon the tool <b>110</b> by known methods, including for example laying together individual plies of pre-impregnated composite to create the final laminated structure. The composite part <b>216</b> can be a complex shape due to the geometries of the multi-segment tool <b>110</b>. The composite can be comprised of a reinforcement and a matrix, such as described with the first embodiment above. The segment of the top portion <b>132</b> that extends above the fairings <b>126</b> serves as an upper sealing surface <b>137</b> for the vacuum barrier <b>220</b>. The outer surface of the base <b>139</b> serves as a lower sealing surface <b>133</b> for the vacuum barrier <b>220</b>. The vacuum barrier <b>220</b> extends over composite <b>216</b> and first, second and third tools (not shown in <figref idref="DRAWINGS">FIG. 15</figref>). Vacuum barrier <b>220</b> is secured to upper sealing surface <b>137</b> and lower sealing surface <b>133</b> using securing methods known to those in the art. In a preferred embodiment, the vacuum barrier <b>220</b> is sealed by a breather cloth and bagging putty (not shown), as is known in the art. Further processing can occur to cure the composite part <b>216</b> in the similar manner as discussed in relation to the first embodiment above.

0057<figref idref="DRAWINGS">FIG. 16</figref> is a schematic view, illustrating how the components of the multi-segment tool <b>110</b> and composite <b>216</b> are disassembled following curing. Initially vacuum barrier <b>220</b> (not shown in <figref idref="DRAWINGS">FIG. 16</figref>), two portions <b>132</b> and fairings <b>126</b> can be removed from multi-segment tool <b>110</b>. Thereafter, third tool <b>160</b> can be axially removed from multi-segment tool <b>110</b>. Axial removal of third tool <b>160</b> initially leaves composite part <b>216</b> around second tool <b>140</b>. Composite part <b>216</b> can then be removed from first and second tools <b>130</b> and <b>140</b>. Subsequent steps can include removal of the second tool <b>140</b> for storage and/or cleaning. Following disassembly, first <b>130</b>, second <b>140</b>, third <b>160</b> tools, and fairings <b>126</b> can be used to reconstruct multi-segment tool <b>110</b> for subsequent composite part formation.

0058This invention permits more than one removable piece of tooling to be used in conjunction with other tools, without the requirement of vacuum sealing surfaces between the tools. A vacuum barrier can be sealed to a single structure, and capture any intermediate tools along with the preform or composite. This eliminates the need to have sealing surfaces between removable tools, thereby minimizing leak exposure and the number of resulting seams. This method is advantageous for 360 degree tooling applications, but also can be used in other non-360 degree applications. Since intervening pressure seals are not required, the interfaces between upper and lower parts can be made with greater mechanical tolerances.

0059In addition, the use of minimal components ensure proper alignment as described above, which often is a problem with multi-segmented bond tooling. The use of indexes helps ensure accurate mating or clocking of tool sections and profiles.

0060Embodiments of this invention provide many advantages over prior art methods. Since the vacuum barrier is attached to portions (e.g., top and bottom as shown in embodiments) of a first tool that is itself vacuum-tight, the lower profile (e.g., element <b>145</b>) and upper profile (e.g., element <b>165</b>) of the embodiments that receive the preform need not be vacuum-tight. Hence the lower profile and upper profile (when combined, sometimes called in the art a “facesheet”) can accommodate tool holes, through bushings, and other discontinuities that often are needed for mechanical assembly, tool replacement and cleaning. Hence, the facesheet can have greater tolerances for machined parts, and broader standards for welding around holes and projections that otherwise would increase tool manufacturing complexity. Such tolerances, through holes and other often minor incongruities in the facesheet have limited negative impact on vacuum integrity. This advantage simplifies overall tool construction and allows for more efficient tool turnaround and cleaning following use.

0061The above descriptions of various embodiments of the invention are intended to describe and illustrate various elements and aspects of the invention. Persons of ordinary skill in the art will recognize that certain changes and modifications can be made to the described embodiments without departing from the scope of the invention. All such changes and modifications are intended to be within the scope of the appended claims.