US20070272346A1

US20070272346A1 - System and method for consolidating dry fabric around a mandrel

Info

Publication number: US20070272346A1
Application number: US11/438,964
Authority: US
Inventors: Peter Shpik; Stan Eckert; James R. Lander; Tracey Kenneth Peters; Suzanne Looper; Robert Eric Baker
Original assignee: GKN Westland Aerospace Inc
Current assignee: GKN Westland Aerospace Inc
Priority date: 2006-05-23
Filing date: 2006-05-23
Publication date: 2007-11-29
Also published as: WO2007139623A2; EP2027049A2; JP2009538261A; WO2007139623A3; CN101479175A

Abstract

A system and method for wrapping fabric around a mandrel including providing a drum of fabric and a mandrel, removing a portion of the fabric from the drum and securing the fabric to the mandrel, rotating the mandrel such that the fabric wraps around the mandrel, and applying pressure to the fabric as the fabric is being wrapped around the mandrel to consolidate the fabric about the mandrel.

Description

BACKGROUND OF THE INVENTION

Embodiments of the present invention generally relate to a system and method for making fiber preforms by consolidating dry fiber fabric around a mandrel tool and, more particularly, to a system and method for applying an external force to dry fabric as it is consolidated in layers around a mandrel tool in order to prevent the fabric from sagging, distorting, and moving during the consolidation process.
In the composite industry, cylindrical fiber preforms made of consolidated dry fiber fabric are used in numerous applications requiring a sturdy, hollow, generally cylindrical structure, such as a plane fuselage, a nacelle, the tail cone of a helicopter, and/or a case. The fiber preforms are made by tightly wrapping a sheet of dry fiber fabric, with the option of applying or pre-applying a light adhesive/resin, around a generally cylindrical mandrel in a series of layers—not unlike a long sheet of paper towels being wrapped around a tube—until the wrapped fabric forms a generally cylindrical structure having the desired thickness, dimensions, and outer diameter for the intended application of the fiber preform. Resin is then added to the bundle of fabric and the structure is heat treated to consolidate and strengthen the fabric into a structure. The fabric may be made of any number of fiber materials such as carbon, glass, or other man-made or other natural fibers, for example.
The fabric is typically tightly wrapped about the mandrel so as to avoid any wrinkles or folds, which may compromise the overall strength of the final fiber-preform structure. This fabric may contain a small amount of resin applied thereto before or during the wrapping process. However, as the fabric is wrapped around the mandrel, and is overlapped around itself, the fabric can become loose and move, bulky in areas, and in general, not tightly wrapped around the mandrel. Therefore, periodically during the wrapping process, the wrapped fabric has to undergo a consolidation process, or a vacuum debulk process, where a solid sheet is placed over the wrapped fabric. A vacuum is then created within the solid sheet such that the fabric is pulled tight and consolidated. A heat treatment process may be applied to assist in the consolidation effort to bind and hold the structure intact. After the heat treatment process, the solid sheet is then removed and the wrapping process begins again. The vacuum debulk process is repeated several times throughout the wrapping process, typically once after about every five to seven layers are wrapped around the mandrel. Therefore, for a fiber preform requiring 42 layers of fabric wrapped around the mandrel, the process of wrapping the fabric will have to be interrupted six to seven times so that the wrapped fabric can undergo vacuum debulking and the consolidation process.
The conventional method and system of consolidating dry fabric around a mandrel to make a fiber preform suffers from several drawbacks. The process of vacuum debulking the fabric is very time consuming and costly, especially when the process is performed numerous times while making a single fiber preform. Another drawback is the application of heat treatment option, which requires time to heat and cool the fabric before the solid film may be removed. For example, due to the time required to prepare for, and perform, the process of vacuum debulking plus the option of applying heat, 30 plus days may be required to finish a preform application having 42 layers of fabric. The additional cost of the tools, labor, and energy for performing the vacuum debulking process is also considerable.
Thus, a need exists for an efficient system and method for effectively consolidating dry fabric, holding the fabric in place, preventing fabric movement and fabric distortion, and eliminating the need for the heat treatment process of the fabric wrapped around a mandrel.

BRIEF SUMMARY OF THE INVENTION

Certain embodiments of the present invention include a system for wrapping fabric around a mandrel. The system may include a sheet of fabric, a mandrel configured to receive the fabric, and at least one fiber and/or fabric tow line. The sheet of fabric is secured to the mandrel and the tow line is secured to one of the fabric and mandrel, and the mandrel rotates such that the fabric and the tow line are wrapped around the mandrel. The tow line is configured under specified tension to apply pressure to the fabric as the fabric is wrapped around the mandrel.
Certain embodiments of the present invention provide a system that may include a sheet of fabric and a mandrel configured to receive the fabric, wherein the sheet of the fabric is secured to the mandrel and the mandrel rotates such that the fabric is wrapped around the mandrel. The system may further include a roller head that has at least one spring-loaded roller attached thereto, wherein the roller head is configured to be placed into position about the mandrel such that the roller rotatably engages the fabric on the mandrel and applies pressure to the fabric as the fabric is wrapped around the mandrel.
Certain embodiments of the present invention provide a system that may include a roller assembly defining a gap configured to receive the mandrel. At least one roller support carrying at least one spring-loaded roller attached thereto is configured to be positioned about the mandrel such that the mandrel is received in the gap and such that the roller rotatably engages the fabric on the mandrel and applies pressure to the fabric as the fabric is wrapped around the mandrel.
Certain embodiments of the present invention provide a method for wrapping fabric around a mandrel. The method includes providing a drum of fabric, providing a mandrel, removing a portion of the fabric from the drum and securing the fabric to the mandrel, rotating the mandrel such that the fabric wraps around the mandrel, and applying pressure to the fabric as the fabric is being wrapped around the mandrel to consolidate the fabric about the mandrel.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates an isometric front view of a system for consolidating fabric to form a fiber preform according to an embodiment of the present invention.

FIG. 2 illustrates an isometric front view of a system for consolidating fabric to form a fiber preform according to an embodiment of the present invention.

FIG. 3 illustrates an isometric front view of a system for consolidating fabric to form a fiber preform according to an embodiment of the present invention.

FIG. 4 illustrates an isometric front view of a system for consolidating fabric to form a fiber preform according to an embodiment of the present invention.

FIG. 5 illustrates a bottom view of the roller head of FIG. 4 according to an embodiment of the present invention.

FIG. 6 illustrates an isometric front view of a system for consolidating fabric to form a fiber preform according to an embodiment of the present invention.

FIG. 7 illustrates an isometric front view of a flange according to an embodiment of the present invention.

The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an isometric front view of a system 10 for consolidating dry fiber fabric to form a fiber preform according to an embodiment of the present invention. The system 10 includes a roll 14 of dry fabric 18 wrapped around a drum or spool 22. The drum 22 is mounted to a base 24 and is configured to rotate. The fabric 18 may be pulled off of the drum 22 as a continuous sheet 26 as the drum 22 rotates in the direction of arrow A. The fabric 18 may be made of any number of materials and the sheet 26 may have any width or length. By way of example only, the fabric 18 may be made from carbon glass, or other man made or other natural fibers and/or may be a woven, braided, unidirectional, crimped or non-crimped, or wool-stitched fabric. The drum 22 may come in a variety of sizes and shapes and the fabric 18 may be fabricated with any number of orientations or constructions that provide the mechanical properties required for a particular application.
The system 10 further includes a mandrel 30 having a cylindrical body 34 formed with conical profiles 36 and rims 38. The mandrel 30 may have any number of sizes, shapes, and configurations. By way of example only, the mandrel 30 may be significantly longer and have a greater diameter and circumference than the drum 22 and may be significantly longer than the width of the sheet 26 of fabric 18. The mandrel 30 may be generally cylindrical, or may be barrel shaped, or have any number of other shapes that correspond to the desired shape of the end-product fiber preform. Optionally, the mandrel 30 may not have rims 38 such that the body 34 may taper off at its ends. The mandrel 30 may be made of any number of materials, for example, composite, plastic, or metal. The mandrel 30 is mounted to a base 42 such that the mandrel 30 is proximate the roll 14 of fabric 18 and is configured to rotate in the direction of arrow B.
The system 10 also includes spools 46 mounted to a base 47 and positioned generally above the roll 14. Each spool 46 carries wrapped thereon a tow line 50 or strand of material. The spools 46 are configured to rotate in the direction of arrow C as the tow lines 50 are pulled off of the spools 46 in the direction of arrow D. Each spool 46 may be any number of sizes in length and diameter. The tow lines 50 may be wrapped around the spools 46 in a spiral orientation like fishing line is wrapped about a fishing reel. By way of example only, the tow lines 50 may be made of fiber or fabric and may be a strand or a sheet. The tow lines 50 may be made from plastic, glass, carbon, or any other man made or other natural fibers and may have any number of different thicknesses or widths. Each spool 46 is mounted to a platform 54 having a circular tow guide 58 through which the tow line 50 extends from the spool 46. The tow guide 58 guides the tow line 50 extending from the spool 46 such that, as the tow line 50 is pulled from the spool 46, the tow line 50 extends from the tow guide 58 at a fixed angle with respect to the spool 46. The tow lines 50 extend from the tow guides 58 through a tensioning bar 62 that is positioned between the spools 46 and the mandrel 30. The tensioning bar 62 can be adjusted to control the amount of tension in each individual tow line 50 extending from a spool 46 to the mandrel 30 and fabric 18.
In operation, before the fabric 18 is first wrapped around the mandrel 30, a resin is added to the exposed body 34 and/or conical profile 36 of the mandrel 30. The fabric 18 is then pulled from the drum 22 and an end of the sheet 26 is placed on at least one of the body 34 and a conical profile 36 of the mandrel 30 over the adhesive. The tow lines 50 are then pulled from the spools 46 and ends of the tow lines 50 are placed on top of the fabric 18 on the mandrel 30 at the end of the fabric 18. The tow lines 50 are then secured to the fabric 18 or the mandrel 30 by adhesive and/or tacks. Alternatively, the tow lines 50 can be tied to the fabric 18 or mandrel 30. The tow lines 50 are positioned over the surface of the fabric 18 in such a way as to evenly distribute pressure across the fabric 18 as the fabric 18 and tow lines 50 are wrapped around the mandrel 30. The mandrel 30 is then rotated in the direction of arrow B such that the sheet 26 of fabric 18 is pulled from the drum 22 and wrapped around the body 34 and/or the conical profile 36 of the mandrel 30. Similarly, as the mandrel 30 rotates in the direction of arrow B, the tow lines 50 are pulled from the spools 46 in the direction of arrow D and wrap around the fabric 18 as the fabric 18 is wrapped around the mandrel 30. The tow lines 50 are therefore positioned between each overlapped layer of fabric 18 as the fabric 18 wraps around the mandrel 30. The spools 22 may be configured to move laterally as the tow lines 50 are wrapped around the fabric 18 and the mandrel 30 such that the tow lines 50 crisscross each other on the fabric 18 or are otherwise positioned along the fabric 18 in a manner that is not parallel to the edges of the sheet 26 of fabric 18.
As the fabric 18 and tow lines 50 are wrapped around the mandrel 30 together, the tow lines 50 are tightly pulled against the fabric 18 during the wrapping process to hold the layers of fabric 18 tightly against the mandrel 30 and each other, thereby preventing the fabric 18 from moving or forming folds. Fabrics made of different materials and having different weaves may require different amounts of pressure from the tow lines 50 to be kept in place on the mandrel 30. Moreover, different fabrics 18 may require different amounts of consolidation. Therefore, as the tow lines 50 are pulled from the spools 46 and wrapped around the fabric 18 on the mandrel 30, the tensioning bar 62 can be adjusted to increase or decrease the tension on the individual tow lines 50. The tension on the tow lines 50 may be adjusted through the tensioning bar 62 such that the tow lines 50 apply the appropriate amount of pressure on the fabric 18 to keep the fabric 18 tightly in position about the mandrel 30 as it is wrapped thereabout. Alternatively, pressure may be applied to the tow lines 50 by any number of other ways, such as by mounting the spool 46 or the mandrel 30 to a tension device such that either one can be pulled away from the other to increase tension in the tow line 50 as needed. By way of example only, a pressure of anywhere from 10 to 100 pounds may be applied by the tensioning bar 62 to the tow lines 50, and thus to the fabric 18 on the mandrel 30. The mandrel 30 is structured to withstand the pressure applied onto the fabric 18 wrapping thereabout.
During the wrapping process, resin or some other tacky substance may be added to the fabric 18 as the fabric 18 is wrapped around the mandrel 30. The fabric 18 and the resin may be heated during the wrapping process such that the overlapping layers of fabric 18 better adhere to each other and are better consolidated by the pressure applied by the tow lines 50.
After the fabric 18 has been tightly wrapped into a bundle around the mandrel 30 in enough layers so that the fiber preform has the proper thickness for the given application, the fabric 18 and tow line 50 are cut and tied to the bundle. Resin is then applied to the fiber preform bundle by any number of different methods, such as injection or infusion. The fiber preform is then further treated and pressurized in an oven or autoclave until it is appropriately consolidated and hardened. The mandrel 30 is then removed from the preform and an end-user can use the finished fiber preform for the appropriate application.
The spools 46 and tow lines 50 of FIG. 1 can have any number of different orientations to distribute the tow lines 50 across the fabric. By way of example only, the spools 46 may all be positioned along the same plane, or may be positioned with respect to each other such that the tow lines overlap and criss-cross each other on the fabric 18 and thus are more evenly and uniformly distributed across the fabric. Alternatively, instead of being stationary, the spools 46 may oscillate such that the tow lines 50 crisscross each other on the fabric 18. Alternatively, the system 10 may include any number of different spools 46 distributing tow lines 50 across the fabric 18. By way of example only, the system 10 may include anywhere from 1 to 10 spools 46 that distribute tow lines 50 that either criss-cross, or are parallel to, each other. The number and arrangement of the spools 46 may be chosen to best apply and distribute the appropriate amount of pressure on a particular kind of fabric for a particular kind of application.
FIG. 2 illustrates a front isometric view of a system 70 for consolidating dry fabric to form a fiber preform according to an embodiment of the present invention. The system 70 includes fabric 18 being fed from a drum 22 to a mandrel 30. The fabric 18 may have a weave and pattern such that the surface of the sheet 26 of fabric 18 is uneven and not generally smooth. Overlapped layers of such a pattern may be more likely to form folds or wrinkles therebetween. The system 70 includes a single spool 74 positioned above the drum 22 that includes numerous strands or tow lines 58 extending therefrom to the fabric 18 around the mandrel 30. The tow lines 58 operate in the same fashion as the tow lines 50 of the system 10 shown in FIG. 1. As the fabric 18 is wrapped around the mandrel 30, the tow lines 50 apply pressure to the fabric 18 as needed to consolidate the fabric 18 about the mandrel 30. Because the tow lines 50 all extend from the same spool 74, the pressure applied by the tow lines 50 is centralized and distributed along the fabric 18 to tightly hold uneven fabric layers down on each other and prevent folds. Alternatively, the tow lines 50 may extend from more than one spool or each tow line 50 may extend from its own spool.
FIG. 3 illustrates a front isometric view of a system 80 for consolidating dry fabric to form a fiber preform according to an embodiment of the present invention. The system 70 includes fabric 18 being fed from a drum 22 to a mandrel 30 like the embodiments of FIGS. 1 and 2. Again, the fabric 18 may have a weave and pattern such that the surface of the sheet 26 of fabric 18 is uneven and not generally smooth. The system 80 includes a single spool 84 positioned above the drum 22 that includes a single wide sheet or tow line 58 extending therefrom to the fabric 18 around the mandrel 30. The tow line 58 may be as wide as the fabric 18 and operates in the same fashion as the tow lines 50 of the systems 10 and 70 shown in FIGS. 1 and 2, respectively. By way of example only, the tow line 58 may be any type of fabric. The pressure applied by the tow line 50 as the tow line 50 and fabric 18 are wrapped around the mandrel 30 is distributed across the fabric 18 to tightly hold the uneven fabric layers down on each other and prevent folds. Alternatively, the tow line 58 may be a single netting or mesh and not a sheet of material. Alternatively, the system 80 may include multiple tow lines 50 that are thinner than the tow line 50 shown in FIG. 3 that each extend from a separate spool and are distributed across the fabric 18.
Alternatively, each embodiment shown in FIGS. 1-3 may include tow lines 50 of varying thickness. By way of example only, a tow line 50 may have a width ranging from ⅛ of an inch to 1 foot depending on factors such as the fabric and the application for the fiber preform. By way of example only, a tow line 50 may have a thickness ranging from 0.001 of an inch to 0.125 depending on factors such as the fabric, application for the fiber perform and/or the force needed to consolidate the fiber perform.
FIG. 4 illustrates an isometric front view of a system 100 for consolidating dry fabric to form a fiber preform according to an embodiment of the present invention. The system 100 includes a roll 14 of fabric 18 and a mandrel 30 with the fabric 18 partially wrapped around the mandrel 30. The system 100 also includes a roller head 104 that is mounted on a piston 108 such that the roller head 104 is positioned above the mandrel 30. Alternatively, the roller head 104 may be mounted to any number of other spring-loaded, or actuated structures. The roller head 104 includes a base 116 having a top surface 120 which is connected to the piston 108 and a bottom surface 124 from which extends roller assemblies 128. Each roller assembly 128 includes a cylindrical roller 140 rotatably mounted to a roller frame 136 that is connected to the base 116 by a spring 132. The roller assemblies 128 extend generally perpendicularly from the bottom surface 124 of the roller head 104. Two end roller assemblies 130 extend from the bottom surface 124 of the roller head 104 at a non-perpendicular angle. Alternatively, each roller assembly 128 and 130 may extend from the bottom surface 124 of the roller head 104 at any number of different angles as needed for a particular application.
FIG. 5 illustrates a bottom view of the roller head 104 of FIG. 4. The roller assemblies 128 and 130 are aligned along the bottom surface 124 of the roller head 104 in two parallel rows 144 with each roller assembly 128 in a row overlapping a gap 148 between adjacent roller assemblies 128 in the other row. Alternatively, any number of roller assemblies 128 and 130 may be aligned along the bottom surface 124 of the roller head 104 in any number of different alignments, arrays, rows, or orientations as needed for a particular application. Alternatively, the size of rollers 140 may vary. By way of example only, the roller head 104 may include at least one roller 140 that extends across the length of the bottom surface 124 from side wall 152 to side wall 152. By way of example only, the roller head 104 may include at least two rollers 140 of different sizes.
Returning to FIG. 4, in operation, the fabric 18 is attached to the mandrel 30 by a resin and then the roller head 104 is lowered in the direction of arrow E on top of the fabric 18 on the mandrel 30 such that the rollers 140 on the roller assemblies 140 engage the fabric 18 at a generally perpendicular angle and press the fabric 18 against the mandrel 30. The mandrel 30 is then rotated in the direction of arrow B such that the fabric 18 begins to wrap around the mandrel 30. As the fabric 18 passes between the mandrel 30 and the roller head 104, the rollers 140 are pushed against the fabric 18 by the springs 132 and/or the piston 108 such that the rollers 140 apply pressure to the fabric 18. The rollers 140 of the end roller assemblies 130 apply angular pressure to the fabric 18. The rollers 140 also rotate in the direction of arrow F as the fabric 18 passes under the rollers 140. Therefore, the spring-loaded rollers 140 apply a compressive force on the fabric 18 as it is wrapped around the mandrel 30 without resisting the progress of the fabric 18 in such a manner as to damage the fabric 18. The pressure applied by the rollers 140 consolidates the fabric to prevent folds or wrinkles from forming in the fabric 18 and to keep the fabric 18 tightly wrapped around the mandrel 30.
When the fabric 18 is wrapped around the mandrel 30 to the desired thickness, the fabric 18 is cut and the loose end of the fabric 18 is secured to the bundle of wrapped fabric 18 by resin and is pressurized by the rollers 140. The roller head 104 is then pulled away from the bundle of fabric 18 in the direction of arrow G. The bundle of fabric 18 may be treated with resin and heat treated to complete the fiber preform product.
The rollers 140 can be used to apply pressure to the fabric 18 regardless of the contours or textures of the fabric 18. By way of example only, the fabric 18 of FIG. 4 may have an uneven texture due to a criss-cross weave. The rollers 140 can be sized and orientated to roll along the contours of a particular fabric and apply pressure along both the “peaks” and “valleys” along the surface of the fabric. For each kind of fabric having a specific contour, a different assembly of rollers 140 having different sizes and orientations may be used to apply the appropriate amount of pressure along the surface of the particular fabric to properly consolidate the fabric. Furthermore, the pressure applied by the rollers 140 through the springs 132 and/or the piston 108 may be adjusted depending on how tight and consolidated a fabric has to be for a particular application.
Again, during the wrapping process, resin or some other tacky substance may be added to the fabric 18 as the fabric 18 is wrapped around the mandrel 30. The pressure applied by the rollers 140 helps the adhesive hold adjacent layers of fabric 18 tightly together. Additionally, the fabric 18 and the resin may be heated during the wrapping process such that overlapping layers of fabric 18 better adhere to each other and are better consolidated by the pressure applied by the rollers 140. By way of example only, the roller head 104 may include a heating unit that applies heat to the fabric 18 as the fabric 18 passes under the rollers 140.
Additionally, the system 100 of FIG. 4 may include more than one roller head 104 positioned around the mandrel 30 to apply pressure to the wrapped fabric 18 at different points along the mandrel 30. By using multiple roller heads 104, more pressure is applied to the fabric 18 for a longer period of time as the fabric 18 is wrapped around the mandrel 30 to further consolidate the fabric 18.
FIG. 6 illustrates an isometric front view of a system 200 for consolidating dry fabric to form a fiber preform according to an embodiment of the present invention. The system 200 includes a roll 14 of fabric 18 and a mandrel 30, with the fabric 18 partially wrapped around the mandrel 30. The system 200 also includes a roller assembly 204. The roller assembly 204 includes a main roller housing 208 having a semi-circular gap 212 defining a perimeter or inner contour 214 along curved side walls 216. The gap 212 is generally sized to receive a portion of the mandrel 30 within the main roller housing 208. The main roller housing 208 is mounted on rails 220 proximate the mandrel 30 such that the main roller housing 208 may be slid, or otherwise moved in relation to the mandrel 30, such that the mandrel 30 may be positioned within the gap 212. Alternatively, the main roller housing 208 may be mounted on any number of other mechanisms that can be used to move the main roller housing 208 in position about the mandrel 30.
The main roller housing 208 of the roller assembly 204 includes a series of roller supports or roller rails 222 mounted therein along the inner contour 214 of the side walls 216. Each roller rail 222 includes row of cylindrical rollers 224 rotatably mounted to roller frames 228 that are connected to the roller rail 222 by springs 232. The rollers 224 are positioned within the main roller housing 208 generally along the inner contour 214 of the side walls 216 and may extend past the side wall 216 and into the gap 212. The main roller housing 208 may include any number of roller rails 224 along the inner contour 214 of the gap 212 from a top end 236 of the main roller housing 208 to a bottom end 240. The roller rails 222 may have any number of rollers 224 of different sizes and shapes extending therefrom and positioned along the inner contour 214 of the side walls 216. The rollers 224 extend generally perpendicularly from the roller rails 222. Alternatively, each roller 224 may extend from a roller rail 222 at any number of different angles as needed for a particular application. Alternatively, any number of rollers 224 may be aligned along a roller rail 222 in any number of different alignments, arrays, rows, or orientations as needed for a particular application. Alternatively, the size of the rollers 224 may vary. By way of example only, a roller rail 222 may include at least one roller 224 that extends across the length of the roller rail 222. By way of example only, a roller rail 222 may include at least two rollers 224 of different sizes.
In operation, the fabric 18 is attached to the mandrel 30 by an adhesive and then the roller assembly 204 is slid along the rails 220 in the direction of Arrow H until the mandrel 30 is received within the gap 212 and the rollers 224 engage the mandrel 30 and the fabric 18 at a generally perpendicular angle. The mandrel 30 is then rotated in the direction of arrow B such that the fabric 18 begins to wrap around the mandrel 30 in layers. As the fabric 18 passes between the mandrel 30 and the rollers 224 on the series of roller rails 222, the rollers 224 are pushed against the fabric 18 by the springs 232 such that the rollers 224 apply pressure to the fabric 18. The rollers 224 also rotate in the direction of arrow F as the fabric 18 passes under the rollers 224. Therefore, the spring-loaded rollers 224 apply a compressive force on the fabric 18 as it is wrapped around the mandrel 30 without resisting the progress of the fabric 18 in such a manner as to damage the fabric 18. By using multiple rails 222 of rollers 224 along the gap 212 from the top end 236 to the bottom end 240 of the main roller housing 208, the fabric 18 is repeatedly pressurized as it passes on the mandrel 30 through the roller assembly 204. Such repeated pressurization consolidates the fabric tightly around the mandrel 30.
The force applied by the rollers 224 to the fabric 18 may be adjusted by moving the main roller housing 208 closer to, or further from, the mandrel 30 along the rails 220. Alternatively, the main roller housing 208 may be adjusted in other ways so as to adjust the pressure applied by the rollers 224 to the fabric 18. Alternatively, different springs 232 may be used to apply different amounts of force on the fabric 18 through the rollers 224 depending on the consolidation required for a particular fabric 18.
The pressure applied by the rollers 224 consolidates the fabric 18 to prevent folds or wrinkles from forming in the fabric 18 and to keep the fabric 18 tightly wrapped around the mandrel 30. When the fabric 18 is wrapped around the mandrel 30 to the desired thickness, the fabric 18 is cut and the loose end of the fabric 18 is secured to the bundle of wrapped fabric 18 by adhesive and is pressurized by the rollers 224. The roller assembly 204 is then slid away from the bundle of fabric 18 on the rails 220. The bundle of fabric 18 is then treated with resin and treated in the oven to complete the fiber preform product.
In an alternative embodiment, the roller assembly 204 may be configured to receive most of the mandrel 30 within a gap lined with the roller rails 222. By way of example only, the roller assembly 204 may be configured to receive generally about three-fourths of the mandrel 30 (such as by engaging generally 270 degrees of the cylindrical mandrel) at any given time. The more of the mandrel 30 that is received in the gap, the more rollers 224 that can engage the fabric 18 and consolidate the fabric 18 as it is wrapped around the mandrel 30.
FIG. 7 illustrates an isometric front view of a flange 250 according to an embodiment of the present invention. Referring to FIG. 1, in some applications, creases or contours may be added to the fabric 18 such that the fabric 18 is pre-shaped for wrapping around a particular mandrel 30. For example, where the mandrel 30 has rims 38 extending out from the body 34 and the fabric 18 is wider than the body 34, the fabric 18 may be shaped to wrap around the body 34 and along the sides of the inner rims 38 of the mandrel 30. Returning to FIG. 7, the flange 250 has a generally flat base 254 formed with side walls 258 extending therefrom. Each side walls 258 extends upward from the base 254 at an angle. In operation, the flange 250 may be used with any of the systems 10, 100, or 200 of FIGS. 1-6 to form the fabric 18 prior to the fabric 18 being fed onto the mandrel 30. That is, the flange 250 is positioned between the mandrel 30 and the roll 14 such that, as fabric 18 is fed from the drum 22 to the mandrel 30, the fabric 18 is pulled over the flange 250. The side walls 258 engage the fabric 18 to form creases along the fabric 18 such that the fabric 18 is formed to fit along the body 34 and rims 38 of a mandrel 30 as the fabric 18 is wrapped around the mandrel 30.
The embodiments of the present invention provide many benefits over conventional methods and systems for wrapping dry fabric around a mandrel to make a fiber preform. The embodiments apply pressure to, and consolidate, the fabric as the fabric is wrapped around the mandrel without a need to stop the wrapping process to vacuum debulk the bundle of fabric. Thus, the embodiments save considerable amounts of time, money, materials, energy, and labor in preparing cylindrical fiber preforms. For example, using the embodiments of the present invention, a fiber preform that would ordinarily take up to 30 days to prepare using the vacuum debulk method may only take roughly 2-3 days to prepare.
While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A system for wrapping fabric around a mandrel, comprising:

a sheet of fabric;

a mandrel configured to receive said fabric; and

at least one tow line, wherein said sheet of said fabric is secured to said mandrel and said tow line is secured to one of said fabric and mandrel, said mandrel rotating such that said fabric and said tow line are wrapped around said mandrel, said tow line being configured to apply pressure to said fabric as said fabric is wrapped around said mandrel.

2. The system of claim 1, further including a tensioning mechanism that engages said tow line and applies tension to said tow line such that said tow line applies pressure to said fabric.

3. The system of claim 1, wherein said tow line is carried on a spool and as said tow line is wrapped around said mandrel, said tow line is pulled from said spool.

4. The system of claim 1, wherein said sheet of fabric is carried on a drum and said fabric is pulled from said drum as said fabric is wrapped around said mandrel.

5. The system of claim 1, wherein said tow line is secured to said fabric by a resin.

6. The system of claim 1, wherein said tow line is one of a fiber strand and a fabric sheet.

7. The system of claim 1, further including a plurality of tow lines.

8. The system of claim 1, wherein a resin is added to said fabric to secure layers of said fabric theretogether as said fabric is wrapped around said mandrel.

9. A system for wrapping fabric around a mandrel, comprising:

a sheet of fabric;

a mandrel configured to receive said fabric, wherein said sheet of said fabric is secured to said mandrel and said mandrel rotates such that said fabric is wrapped around said mandrel; and

a roller head, said roller head including at least one spring-loaded roller attached thereto, wherein said roller head is configured to be positioned about said mandrel such that said roller rotatably engages said fabric on said mandrel and applies pressure to said fabric as said fabric is wrapped around said mandrel.

10. The system of claim 9, wherein said roller is connected to a spring.

11. The system of claim 9, wherein said roller head includes a plurality of rollers.

12. The system of claim 9, further including a plurality of said roller heads positioned about said mandrel to engage said fabric and apply pressure to said fabric.

13. The system of claim 9, wherein said roller head is mounted to a spring-loaded device.

14. A system for wrapping fabric around a mandrel, comprising:

a sheet of fabric;

a roller assembly, said roller assembly defining a gap configured to receive said mandrel and including at least one roller support along said gap, said roller support carrying at least one spring-loaded roller attached thereto, wherein said roller assembly is configured to be positioned about said mandrel such that said mandrel is received in said gap and such that said roller rotatably engages said fabric on said mandrel and applies pressure to said fabric as said fabric is wrapped around said mandrel.

15. The system of claim 14, wherein said roller support is a rail carrying a plurality of rollers.

16. The system of claim 14, wherein said roller assembly includes a plurality of roller supports carrying rollers positioned along a perimeter of said gap such that said rollers engage said fabric as said fabric is wrapped around said mandrel.

17. The system of claim 14, wherein said roller is connected to said roller support by a spring.

18. A method for wrapping fabric around a mandrel, comprising:

providing a drum of fabric;

providing a mandrel;

removing a portion of the fabric from the drum and securing the fabric to the mandrel;

rotating the mandrel such that the fabric wraps around the mandrel; and

applying pressure to the fabric as the fabric is being wrapped around the mandrel to consolidate the fabric about the mandrel.

19. The method of claim 18, wherein said applying pressure step comprises:

securing a tow line to one of the fabric and mandrel;

wrapping the tow line about the mandrel with the fabric; and

applying tension to the tow line such that the tow line applies pressure to the fabric as the fabric is being wrapped around the mandrel.

20. The method of claim 18, wherein said applying pressure step comprises:

providing at least one spring-loaded roller; and

positioned the roller about the mandrel such that the roller rotatably engages the fabric on the mandrel and applies pressure to the fabric as the fabric is wrapped around the mandrel.