HK1014998B - Rotary needling process for making needled fibrous structures - Google Patents

Description

Rotary needling process for making needled fibrous structures

The present invention relates to the field of needle punching for producing fibrous structures. More particularly, the present invention relates to rotary needling wherein a plurality of forked or barbed needles are repeatedly driven into a fibrous structure disposed on a bed plate, which fibrous structure rotates about an axis of rotation.

Rotary needling and machinery are well known in the textile industry. According to one of the prior art methods, a plurality of fork or hook needles are repeatedly driven into a fiber structure provided on a plane of a needle-penetrable support, which support is rotated about an axis of rotation perpendicular to the plane of the support, as is described in us 5,217,770 and 4,955,123 and german patent application DE2911762a 1. This particular rotary needling process can be used to make both round and annular fiber structures and has been found to be useful in the manufacture of aircraft brake disc preforms which are suitable for further processing into composite aircraft brake discs, including infiltration into a bonding matrix according to various methods known in the pertinent industry.

According to the state of the art, needle-penetrable bearings have a needle-penetrable medium (e.g. plastic, elastomer, foam or elastomer, or bristles of a brush) forming a plane on which fibrous material can be deposited, while the needle-penetrable bearing rotates about an axis of rotation perpendicular to the plane. Typically, the fibrous material deposited on the flat surface is first attached with a needle-penetratable media to move the fibrous material with the needle support, and then additional fibrous material is added until an attached fibrous structure having the desired final thickness is produced. The fibrous structure must then be separated from the needle-penetratable medium by peeling, prying or cutting to remove the fibrous structure from the support. Stripping fiber structures from needle-penetrable media is not good for certain thick fiber structures such as aircraft brake disc preforms because it can distort and often damage the fiber structure. If distortion and damage are to be considered, the fibrous structure may be cut from a needle-penetratable medium. The latter method, however, leaves residual fibrous material on the needle-penetratable medium that must be removed before the next fibrous structure can be made, which is cumbersome and time-consuming.

In some methods of this type, this has been done, in which additional fibre layers are added and needled, but the needles are not driven into the media that can be penetrated by the needles, i.e. the needle penetrates the fibre material deposited on the support to the full extent. Certain methods of manufacturing aircraft brake disc preforms take advantage of this feature. The fibrous structures so produced are susceptible to breaking apart from the needle-penetratable medium when the fibrous structure is not yet completed. One way to address this problem is to increase the bonding between the fibrous structure and the needle-penetratable media by increasing the number of fibers fed into the needle-penetratable media. This solution is not good for two reasons: first, such fiber structure is even more difficult to remove, and second, such that even more fibers are left in the needle-penetrable medium to be removed later.

It is therefore an object of the present invention to provide a needling method and support in which the fibrous material deposited on the support is held on the support with sufficient strength until the fibrous structure is completed. It is another object of the present invention to allow the fibrous structure to be easily removed from the needle-penetratable media after completion, leaving little residual fibrous material in the needle-penetratable media.

According to one aspect of the present invention, there is provided a rotary needling method comprising the steps of:

removably securing a needle-penetrable mat (card clothing) to a rotating needling support such that the rotating needling support defines a surface underlying a plurality of felting needles and has a needle-penetrable region, the needle-penetrable mat (card clothing) overlying the surface and being secured to the rotating needling support outside the surface;

rotating a needle-penetratable shim about an axis of rotation;

depositing at least a first layer of fibers on a needle-penetrable mat;

repeatedly driving a plurality of felting needles into the first fibrous layer and the needle-penetrable mat to bond them together;

after the first fibrous layer and the needle-penetratable mat are bonded together, the first fibrous layer and the needle-penetratable mat are removed from the rotating needle bearing.

The invention also provides a rotary needling method, which comprises the following steps: overlaying a needle-penetrable shim over a needle-penetrable medium attached to the base, said needle-penetrable medium forming a planar surface exposed below the plurality of felting needles; removably securing said needle-penetrable insert to said base outside of said planar surface; rotating said base about an axis of rotation perpendicular to said planar surface; depositing at least a first fibrous layer on said needle-penetrable mat; repeatedly driving said plurality of felting needles into said first fibrous layer and said needle-penetrable mat to bond them together; removing said first fibrous layer and said needle-penetratable spacer from said needle-penetratable medium after said first fibrous layer and said needle-penetratable spacer have been joined.

The invention also provides a rotary needling method, which comprises the following steps: stacking a fibrous mat on a needle-penetratable media mounted on a base, said needle-penetratable media defining a planar surface and having a plurality of brush bristles; placing said fibrous mat over said plurality of pins of said base outside of said planar surface to removably secure and clamp said fibrous mat to said base outside of said planar surface; rotating said base about an axis of rotation perpendicular to said planar surface; depositing at least a first fibrous layer on said fibrous mat; repeatedly driving said plurality of felting needles into said first fibrous layer and said fibrous mat to bond them together; stacking a plurality of additional fiber layers on said first fiber layer, one or more layers being added at a time; repeatedly driving said plurality of felting needles into said first fibrous layer and said at least one additional fibrous layer to bond them together; driving said plurality of felting needles repeatedly into said plurality of additional fiber layers to bond said plurality of additional fiber layers one or more at a time without driving said plurality of felting needles into a needle-penetrable medium when only some of said additional fiber layers are bonded; after these bonds are completed, removing the fibrous mat, the first fibrous layer and the plurality of additional fibrous layers from the needle-penetratable media.

The drawings are briefly described as follows:

FIG. 1 is a top view of a rotary needling support, partially broken away, in accordance with one aspect of the present invention.

FIG. 2 is a side view of the rotary needling support of FIG. 1, partially broken away.

Fig. 3 is a side cross-sectional view of the area indicated by 3-3 in fig. 2.

FIG. 4 is a top view of a rotary needling support according to another aspect of the present invention, with portions broken away.

FIG. 5 is a side view of the rotary needling support of FIG. 4, partially broken away.

Fig. 6 is a side cross-sectional view of the area indicated by 6-6 in fig. 5.

FIG. 7 is a side cross-sectional view of a rotary needling support according to another aspect of the present invention.

Various aspects of the present invention are illustrated in fig. 1-6, which are not drawn to scale, wherein like parts are designated by like reference numerals. Referring now to fig. 1 and 2, a rotary acupuncture support 10 is provided in accordance with an aspect of the present invention. It has a base plate 11 on which a surface 18 is formed having a region which can be penetrated by a needle, and an outer base ring 26 which surrounds the surface 18, the outer base ring 26 being rotatable about an axis of rotation 14, the axis of rotation 14 preferably being perpendicular to the surface 18. The base ring 26 may be made in one piece with the base plate 11 or as a separate piece. In the embodiment of fig. 1 and 2, the needle penetrable region expands outwardly in line with surface 18, but may also occupy only a portion of surface 18. A needle-penetratable insert 22 covers the surface 18 and is attached to the outer base ring 26 such that the needle-penetratable insert 22 rotates beneath the needle-punching head 54. The needling head 54 has a plurality of felting needles 20 mounted on a needle board 24, the felting needles 20 being repeatedly driven into the needle-penetrable mat 22 and the needle-penetrable region of the surface 18 during at least a portion of the rotary needling felting process as the needle-penetrable mat 22 rotates beneath the needling head 54. As used herein, the term "felting needles" refers to those needles with tines or hooks that are repeatedly driven into a fibrous structure to increase entanglement and densification of the fibrous structure, as is well known in the art. Suitable felting needles are available from Groz-Beckert, Germany and Foster Needle, Inc., Wisconsin, USA. The needle-penetrable portion of the mat 22 is used as a carrier for the fiber layers to be deposited and bonded thereto by the plurality of felting needles 20. As is well known in the industry, the felting needle 20 is forked or hooked so that it can carry fibers within the fiber bed. The needling head may have various shapes depending on the desired needling action, but in general it extends across the entire width of the fibrous layer to be needled, this "width" being passed under the needling head 54 perpendicular to the direction of the fibrous layer. A plurality of needling heads may be employed, each having a width that corresponds to or is less than the width of the fibrous layers. Also, the needling head 54 may cover only a portion of the circumference of the surface 18 as shown in FIG. 1, or the entire circumference of the surface 18. Any such variations are to be considered within the scope of the present invention.

Two embodiments of actuating the penetrable spacers with needles are shown in fig. 1-6. In both embodiments, the piercing head 54 is reciprocated by a suitable mechanism in a manner well known in the art. The needle support may be moved up and down relative to the felting needle in a direction parallel to the axis of rotation by a suitable mechanism such as a power driven screw jack. The rotary needling support and the needling head are coupled to a frame together with a drive mechanism and a control mechanism. Rotary needling machines and methods which can be used with rotary needling supports according to the present invention are well known in the industry, examples of which are described in us patents 5,217,770 and 4,955,123 and german patent application DE2911762a 1. A detailed description of such machinery is not required here.

In the embodiment shown in fig. 1 and 2, the base plate 11 has a base 12 that is rotatable about an axis of rotation 14 during the needling process and a needle penetrable region below the plurality of felting needles 20. The area penetrable by the needles covers substantially all of the surface 18 for the base plate 11, as the entire surface passes under the plurality of felting needles 20. The area penetrable by the needles may be an array of holes (not shown) or concentric grooves (not shown) on the base 12 aligned with the felting needles 20, or the medium penetrable by needles 16 may be mounted on the base 12, the last being preferred as it may no longer be necessary to align the felting needles 20 with the holes or grooves on the base 12. In this embodiment, the needle penetrable medium 16 overlies a portion of the base 12 and forms a surface 18 that may be perpendicular to the axis of rotation 14. The surface 18 may be planar or non-planar such as concave or convex, depending on the particular needling process and the desired shape of the fibrous structure produced by the process. A needle-penetrable spacer 22 (a portion of which is split to expose surface 18) overlies the needle-penetrable medium 16 and is removably secured to the base 12 outside of the surface 18 in a manner to be described in greater detail below. According to a preferred embodiment, the base 12, the needle-penetratable medium 16, the surface 18, and the needle-penetratable spacer 22 are all circular about the axis of rotation 14, but are more preferably annular about the axis of rotation 14. If surface 18 is annular, a needle-penetratable spacer 22 may be attached to the outside of surface 18 adjacent the outer diameter of surface 18, adjacent the inner diameter of surface 18, or both. Primarily the entire surface 18 passes under the needle board 24 and is penetrated by a plurality of felting needles 20 during at least a portion of the needling process, which typically occurs at the beginning of the process.

The first fibrous layer 48 and one or more additional fibrous layers 50 are stacked on the needle-penetrable medium 16 and the needle-penetrable mat 22 and subjected to one or more needling processes, as will be described in more detail below. The fibrous layers 48 and 50 may take various forms. To produce a disc or ring, the fibrous layers may form a fan of discs or rings, or the fibrous layers may form a spiral band, as exemplified in U.S. patents 5,546,880, 5,417,138, 5,217,770 and 4,955,123. The fibrous layer may have a variety of forms of fibers including carbon fibers and ceramic fibers, and precursors of both fibers, as well as mixtures of these fibers. Polyacrylonitrile (PAN) fiber, Oxidized Polyacrylonitrile Fiber (OPF) are examples of carbon fiber precursors. The individual fiber layers 48 and 50 can be made of, without limitation, fiber bundles, yarns, woven and nonwoven fabrics, knitted fabrics, and felts. The term "fiber bundle" as used herein refers to a strand of continuous long fibers. The term "yarn" as used herein refers to continuous fibers or continuous strands of continuous staple fibers or a mixture of both. Various forms of continuous or discontinuous fibers (staple fibers) may be used to form fibrous layers 48 and 50.

In the example shown in fig. 1 and 2, a needle-penetratable shim 22 is clamped to the base 12. Preferably, an outer base ring 26 is provided which surrounds the surface 18 and is secured to the base 12. A needle-penetratable shim 22 is superimposed on the outer base ring 26. An outer retaining ring 28 overlies the outer base ring 26 and clamps the needle-penetratable spacer 22 therebetween. The outer retaining ring 28 and outer base ring 26 then hold the needle-penetratable spacer 22. As best seen in fig. 3, where corresponding parts have been shown in fig. 1 and 2, they are identified by corresponding reference numerals. A plurality of pointed pins 30 project outwardly from outer base ring 26 parallel to axis of rotation 14. A needle-penetratable shim is superimposed on the outer base ring 26 and pierced by the pin 30. When the outer retaining ring 28 is placed on the outer base ring 26, the plurality of mating holes 32 provided in the outer retaining ring 28 can be aligned with the pointed pins 30 to receive it. Preferably, there are a plurality of pins 30 and holes 32 evenly distributed around the circumference of the two rings 26 and 28. Other ways of holding a needle-penetratable spacer have been contemplated in the practice of the present invention. For example, a toothed surface on the outer retaining ring 28 and a rubber surface on the outer base ring 26, with the needle-penetratable shim 22 clamped between these two surfaces. Outer base ring 26 can be removably attached to base 12 by a plurality of threaded fasteners (not shown) passing through a plurality of holes in outer base ring 26 and engaging a plurality of mating threaded holes (not shown) in base 12, although other suitable methods are possible. It will be apparent to those skilled in the art in light of the disclosure herein that various methods of holding the needle-penetratable shim 22 outside the surface 18 can be readily made, any of which should be considered within the scope of the present invention.

An inner base ring 27 and an inner retaining ring 29 (both shown in phantom) shown in broken away in fig. 1 may be used to attach the needle penetrable shim 22 to the base 12 near the inner diameter of the surface 18, the inner base ring 27 and inner retaining ring 29 having the same characteristics as the outer base ring 26 and outer retaining ring 28 described herein. In this embodiment, the surface 18 surrounds an inner retaining ring 29 and an inner base ring 27. It is preferable to attach a needle-penetratable spacer 22 near the outer diameter. The base 12 is configured to be driven with the outer base ring 26, the two parts being driven in rotation about the axis of rotation 14 by suitable drive means (not shown) which are well known in the industry using rotary needling. It is preferable that the base 12 and outer base ring 26 be driven together because the needle-penetrable spacers are driven by frictional engagement with the base 12 and mechanical engagement with the outer base ring 26, and the outer base ring 26 reduces stress on the spacers 22 at the junction with the outer base ring 26.

The needle-penetrable medium 16 is preferably attached to the base and may be permanently affixed to the base 12. According to a preferred embodiment, the needle-penetrable medium 16 has bristles 52 of a brush affixed to the base 12, as shown in FIG. 3. The needle-penetrable medium 16 may also be a foam elastomer and/or a foam. It has been found in the practice of the present invention that nylon (polyamide) brush bristles 52 are preferred because they are more durable and recyclable. Examples of needle-penetratable media consisting of bristles, pins or needles of brushes are described in german patent applications DE2911762a1 and DE3214831a1, german patent publication 2,306,416 and us patents 3,829,939 and 4,651,393, any of which is suitable for the practice of the present invention. The base 12 is preferably a rigid body and may be made of any suitable material such as metal, plastic and fiber reinforced plastic. The outer base ring 26, outer retaining ring 28 and pin 30 are preferably made of a metal such as steel. The needle-penetrable spacer may be a fibrous sheet and is preferably a woven fibrous sheet. A preferred embodiment of the present invention for making an aircraft brake disc preform from Oxidized Polyacrylonitrile Fiber (OPF) utilizes 14.25 ounce per square yard cotton terry cloth as the needle-penetratable spacer 22, 23 ends per inch and 2.5 to 2.75 ends per inch, a material available as G1250 from Eastbank textile/Eastbank trade company of Macron, Georgia, and from Walton Monore Mills, Monroe, Georgia, USA. The batt wrap works well in the practice of the present invention because it serves as a good carrier for the fibers carried in one or more of the fiber layers 48 and 50 and has good strength against tearing when rotated. Other fibrous layers having similar properties are contemplated, including nonwoven and knit materials, although any should be considered within the scope of the present invention.

In accordance with one aspect of the invention, at least one needle-penetrable pad 22 is provided, and at least one additional needle-penetrable pad may be provided overlying the surface 18 and secured to the rotary acupuncture support 10 outside the surface 18. In this way, two, three or more needle-penetrable spacers 22 may be stacked together and attached to the base 12 outside of the surface 18. The use of stacked needle-penetrable shims 22 is clearly effective if the needle pricks too hard and can damage a single needle-penetrable shim 22. It has been found that stacking two or more shims together provides a support structure that can withstand relatively severe needle sticks. Or the weight of the available needle penetrating shims may be increased rather than using multiple stacked shims. It is appropriate to provide two or more needle-penetratable shims because only one weight of material needs to be specified and kept in stock.

The needle-penetrable shims 22 may be clamped between the outer base ring 26 and the outer retaining ring 28 in a variety of ways, including using threaded fasteners and various clamping devices known in the mechanical industry, such as spring-loaded clamps, screw-action clamps, pneumatic clamps, and hydraulic clamps. As shown in fig. 1 and 2, some embodiments employ a plurality of tabs 34 attached to the base 12. Turning to fig. 3, the function of the tab is to pull the outer retaining ring 28 toward the outer base ring 26, thereby clamping the needle-penetratable shim 22 therebetween. The tab 34 has: a tab body 36, a tab lever 38 pivotally supported on the tab body 36 by a tab pin 40, and a tab cartridge 42 pivotally supported on the tab lever 38 by a cartridge pin 44. The tab lever 38 is rotated clockwise about the tab pin 40 so that the chuck pin 44 is rotated clockwise, causing the tab chuck 42 to move upward and release the outer retaining ring 28. To grip the outer retaining ring 28, the tab lever 38 is rotated counterclockwise to move the tab cartridge downward. A gripping tab 46 is preferably provided on the outer retaining ring 28 to cooperate with the tab cartridge 42 and engage the end thereof. The clamping tabs 46 may be attached to the outer retaining ring 28 by suitable means including screws, rivets and welding. The tab 36 may be attached to the base 12 by any suitable means including screws, rivets and welding. In the example shown in fig. 3, screws 47 are used.

Referring now to fig. 4-6, a rotary acupuncture support 100 is illustrated in accordance with another aspect of the present invention. The rotary acupuncture support 100 is similar to the rotary acupuncture support 10 of fig. 1-2, and like parts in both embodiments are identified by like reference numerals in the drawings. The rotary needling support 100 has a base 111 with a base 112 having a plurality of openings 113 arranged in an array such that a surface 118 is formed on the base 112 in which the needles penetrate. In this embodiment, the area penetrable by the needles corresponds to the area penetrable by a plurality of felting needles and may be all or a portion of the surface 118, depending on the shape of the needling head 54. A plurality of felting needles 20 mounted on a needle board 24 are positioned above the array of holes 113 such that each hole is aligned with an associated needle 20. The area penetrable by the needles may also have an array of concentric grooves (not shown) or a medium penetrable by the needles, such as a brush, may be used to form the entire surface 118 or only a portion of the surface underlying the plurality of felting needles. An outer base ring 126 surrounds the surface 118 and is free to rotate relative to the base plate 111. A needle-penetratable spacer 22 covers surface 118 and is attached to outer base ring 126 in the manner previously described in connection with fig. 1-3. In the embodiment illustrated in fig. 4-6, however, the base plate 111 is fixed against rotation relative to the plurality of felting needles 20, while the needle-penetrable shims 22 are rotated by the rotation of the outer base ring 126. The needle-penetratable shim 22 slides over the surface 118 that remains stationary, while the outer base ring 126 forces the needle-penetratable shim 22 to rotate with it. In this embodiment, a stronger needle-penetratable insert 22, such as a heavier chafer, must be used to prevent the insert from tearing away from the outer base ring 126. An inner base ring may also be provided, similar in construction and operation to outer base ring 126, with the inner base ring being surrounded by surface 118. The inner base ring can be driven together with the outer base ring 126.

The outer base ring 126 (and/or the inner base ring) may be supported, for example, by bearings 156 and forced into rotation by a motor 152 mechanically coupled to the outer base ring 126 with a suitable mechanism. According to a preferred embodiment, a pulley 154 may be attached to the motor shaft, and the outer base ring 126 (and/or inner base ring) is driven by a belt 155. Alternatively, a pinion may be used to engage the inside or outside of the outer base ring (and/or inner base ring). A ring gear may be provided on the outer base ring (and/or the inner base ring) to mesh with the pinion gear. Other drive mechanisms will be apparent to those skilled in the needling machine industry, but any such variation is considered to be within the scope of the present invention.

Referring now to FIG. 7, there is shown a cross-sectional view of a portion of a rotary needling support in accordance with another aspect of the present invention. The lancing support 200 is very similar to the lancing support 10 except that the lancing support 200 has a plurality of spring-loaded collets in place of the tab 34. The spring-loaded clamp 234 has a pair of guides 236 and a clamping bar 238 received within the guides 236. The clamping bar 238 has a shaft portion 240 and a finger portion 242. The two guide frames 236 are each provided with mutually aligned apertures 244, and the shaft portion 240 is received in the apertures 244 to be vertically slidable (movable) in the guide frames 236. The shaft 236 has a spring catch 246 and a spring 248 is compressively disposed between the spring catch 246 and the upper guide 236. The spring 248 pulls the shaft portion 240 downward so that the drive fingers 242 press against the outer retaining ring 28, thus providing the clamping force necessary to clamp the available needle penetrating insert between the outer retaining ring 28 and the outer base ring 26. To release the outer retaining ring 28, the needle penetrable support 200 may be lowered. The end of the shaft portion 240 contacts a release stop 250 when the support 200 is lowered, which stops the clamping bar 238 as the support 200 continues to be lowered, allowing the outer retaining ring 28 to be removed from the fingers 242. The release catch 250 is fixed to the frame (not shown) of the needling machine. When the needle support 200 is lowered a predetermined distance, the collets 234 release the outer retaining ring 28 allowing it to be installed or removed. A spring-loaded collet 234 may be used on any of the embodiments of the present invention.

According to another aspect of the present invention, there is also provided a rotary needling process. Referring again to fig. 2, the method includes the steps of: removably securing a needle-penetrable pad 22 to a rotating needling support 10, the rotating needling support 10 defining a surface 18 underlying a plurality of felting needles 20 and having a needle-penetrable region, the needle-penetrable pad 22 overlying the surface and being secured to the rotating needling support outside the surface 18; rotating the needle-penetratable spacer 22 about an axis of rotation; depositing at least a first layer of fibers on the needle-penetrable mat 22; repeatedly driving a plurality of felting needles 20 into the first fibrous layer 48 and the needle-penetratable mat 22 to bond them together; and removing the first fibrous layer 48 and the needle-penetrable mat 22 from the rotating needle-punched support after the first fibrous layer 48 and the needle-penetrable mat are bonded together. Although the above steps are described in connection with the lancing support 10 of FIGS. 1 and 2, the above-described method can also be used with the lancing support 100 of FIGS. 4 and 5 and the lancing support 200 of FIG. 7.

Still referring to fig. 2, according to another aspect of the present invention, there is provided a method comprising the steps of: stacking a needle-penetratable shim 22 over a needle-penetratable media 16 attached to the base 12, the media defining a planar surface 18; removably securing a needle-penetratable shim 22 to the base 12 outside the planar surface 18; rotating the base 12 about an axis of rotation perpendicular to the planar surface 18; depositing at least a first layer of fibers on the needle-penetrable mat 22; driving a plurality of felting needles 20 into the first fibrous layer 48 and the needle-penetrable mat 22 to bond them together; the first fibrous layer 48 and the needle-penetrable mat 22 are removed from the needle-penetrable medium 16 after the first fibrous layer 48 and the needle-penetrable mat 22 are bonded together. Various features described above in connection with fig. 1-7 may be used in this method.

According to a preferred embodiment, the step of bonding the first fibrous layer 48 and the needle-penetrable mat 22 occurs at least a portion of the time when the plurality of felting needles 20 have penetrated into the needle-penetrable medium 16 but the needle-penetrable mat 22 and the needle-penetrable medium 16 are not bonded or, in other words, the needle-penetrable mat 22 is not adhered to the surface 18. The fibrous structure produced by this step is easily removed from the mat 11.

If the area penetrable by the needle has an array of holes 113 or an array of concentric grooves (not shown) is used, fibers carried through the needle-penetrable pad 22 into the holes 113 or grooves (not shown) will not adhere the needle-penetrable pad 22 to the surface 18 because the fibers are easily pulled out of the holes or grooves. If the brush 52 is used as the needle-penetrable medium 16, the needle-penetrable insert 22 of the above-described batt-encircling fabric would greatly impede the transport of fibers into the brush 52. Adjusting needling parameters to reduce fiber transport is generally not required because the batt wrappings can be an effective barrier to transport of fibers into the brush. After the fibrous mat 22 is removed, very little, if any, of the fibers remain in the brush 52. The finish of the surface 18 of the brush 52 does not appear to have any effect on the tendency of the needle-penetratable pad 22 to stick to the brush 52.

According to another preferred embodiment, the method further comprises the steps of: a plurality of additional fiber layers 50 are stacked on the first fiber layer 48 and a plurality of felting needles 20 are repeatedly driven into the first fiber layer 48 and the plurality of additional fiber layers 50 to combine them. When the final step is applied in conjunction with only some of the additional fiber layers 50, it may not be necessary to drive a plurality of felting needles 20 into the first fiber layer 48, or through the entirety of the plurality of additional fiber layers 50. Typically, these layers are intermediate and/or top added fiber layers 50, which are commonly encountered in relatively thick fiber structures such as aircraft brake disks. In this case, the plurality of felting needles 20 may be driven into the needle-penetratable medium 16 whenever certain fiber layers 48 and 50 are combined (typically at the beginning of the process), whereas the plurality of felting needles 20 may not be driven into the needle-penetratable medium whenever certain fiber layers 50 are combined (typically at the middle and/or end of the process). Each fibrous layer 48 or 50 may be stacked and individually needled onto a previous fibrous layer or layers, or more than one fibrous layer may be stacked on a previous fibrous layer or layers before being subjected to a single needling pass. Fibrous layer 50 may be constructed, without limitation, from a single fibrous loop, several layers of incomplete loops placed side-by-side, and/or a spiral fibrous tape (braided, woven, or knitted). The fibrous layer is preferably formed of Oxidized Polyacrylonitrile Fibers (OPF) used to make aircraft brake disc preforms, but other materials may be used depending on the desired end properties and the intended use of the final fibrous structure, including Polyacrylonitrile (PAN) fibers, carbon fibers, graphite fibers, ceramic fibers, precursors to carbon and ceramic fibers, and mixtures thereof.

According to another aspect of the present invention there is provided a method suitable for making a thick annular fibrous structure such as a composite aircraft brake disc preform comprising the steps of: (a) superposing a needle-penetrable fibrous mat 22 on a needle-penetrable medium 16 attached to the base 12, the medium defining a planar surface 18 and having a plurality of brush bristles; (b) placing the fiber mat 22 over the plurality of pins 30 of the base 12 outside of the planar surface 18 such that the fiber mat 22 is removably secured and clamped to the base 12; (c) rotating the base 12 about an axis of rotation 14 perpendicular to the planar surface 18; (d) depositing at least one first fibrous layer 48 on the fibrous mat 22; (e) repeatedly driving the plurality of felting needles 20 into the first fibrous layer 48 and the fibrous mat 22 to bond them together; (f) stacking a plurality of added fiber layers 50 on first fiber layer 48, one or more layers being added at a time; repeatedly driving the plurality of felting needles 20 into the first fiber layer 48 and the additional fiber layer 50 to bond the at least one additional fiber layer 50 and the first fiber layer 48; (g) repeatedly driving the plurality of felting needles 20 into the plurality of additional fiber layers 50 to combine the plurality of additional fiber layers 50 one or more at a time without driving the plurality of felting needles 20 into the needle-penetrable medium 16 when only some of the additional fiber layers 50 are combined; (h) after these combinations are completed, the fibrous mat 22, the first fibrous layer 48, and the plurality of additional fibrous layers 50 may be removed from the needle-penetrable media 16.

It will be apparent to those skilled in the art that various changes may be made in the invention in light of the above teachings, but any such changes are to be considered within the purview of this invention and the scope of the invention is to be defined in the appended claims.

Claims (23)

1. A rotary needling method comprising the steps of:

removably securing at least one needle-penetrable pad to a rotating needling support, the rotating needling support defining a surface underlying a plurality of felting needles and having a needle-penetrable region, the needle-penetrable pad overlying the surface and secured to the rotating needling support outside the surface;

rotating a needle-penetratable shim about an axis of rotation;

depositing at least a first layer of fibers on a needle-penetrable mat;

repeatedly driving a plurality of felting needles into the first fibrous layer and the needle-penetrable mat to bond them together;

removing said first fibrous layer and said needle-penetratable mat from said rotating needle-punching support after said first fibrous layer and said needle-penetratable mat have been bonded together.

2. The method of claim 1 wherein said needle-penetrable gasket is not adhered to said surface.

3. The method of claim 1, further comprising the steps of:

depositing a plurality of additional fibrous layers on said first fibrous layer;

repeatedly driving said plurality of felting needles into said first fibrous layer and said plurality of additional fibrous layers to bond them together.

4. The method of claim 1 wherein said rotary needling support has a base defining said surface and a needle-penetratable media attached to said base.

5. The method of claim 1, wherein said rotating needling support has a base portion forming said surface and an outer base ring surrounding said surface, said needle-penetratable spacer being attached to said outer base ring, and said needle-penetratable spacer and said base portion rotating with said outer base ring.

6. The method of claim 1 wherein said rotary needling support has a base portion defining said surface and an inner base ring surrounded by said surface, said needle-penetratable spacer being attached to said inner base ring, and said needle-penetratable spacer and said base portion rotating with said inner base ring.

7. The method of claim 1, wherein:

said rotary needling support having a base defining said surface and an outer base ring surrounding said surface, said needle-penetratable spacer being attached to said outer base ring; at the same time

Said rotary needling support having a base forming said surface and an inner base ring surrounded by said surface, said needle-penetratable shim being attached to said inner base ring, and said needle-penetratable shim and said base rotating with said outer base ring and said inner base ring.

8. The method of claim 1, wherein said rotating needling support has a base portion forming said surface and an outer base ring surrounding said surface, said needle-penetratable shim being attached to said outer base ring and being rotated by movement of said outer base ring while said base portion is fixed and not rotating relative to said plurality of felting needles.

9. The method of claim 1, wherein said rotating needling support has a base portion forming said surface and an inner base ring surrounded by said surface, said needle-penetratable shim being attached to said inner base ring and being moved in rotation by said inner base ring, and said base portion being fixed and not rotating relative to said plurality of felting needles.

10. The method according to claim 1, characterized in that,

said rotary needling support having a base defining said surface and an outer base ring surrounding said surface, said needle-penetratable spacer being attached to said outer base ring; at the same time

Said rotary needling support having a base forming said surface and an inner base ring surrounded by said surface, said needle-penetratable spacer being attached to said inner base ring; and said needle-penetratable shim is rotated by said inner base ring and said outer base ring, while said base is fixed and not rotated relative to said plurality of felting needles.

11. The method of claim 1 wherein said axis of rotation is perpendicular to said surface.

12. The method of claim 1, further comprising the steps of:

at least one additional needle-penetratable spacer covering said surface is removably secured to said rotary needling support outside said surface.

13. A rotary needling method comprising the steps of:

overlaying a needle-penetrable shim over a needle-penetrable medium attached to the base, said needle-penetrable medium forming a planar surface exposed below the plurality of felting needles;

removably securing said needle-penetrable insert to said base outside of said planar surface;

rotating said base about an axis of rotation perpendicular to said planar surface;

depositing at least a first fibrous layer on said needle-penetrable mat;

repeatedly driving said plurality of felting needles into said first fibrous layer and said needle-penetrable mat to bond them together;

removing said first fibrous layer and said needle-penetratable spacer from said needle-penetratable medium after said first fibrous layer and said needle-penetratable spacer have been joined.

14. The method of claim 13 wherein said plurality of felting needles penetrate said needle-penetrable medium at least a portion of the time during said step of bonding said first fibrous layer to said needle-penetrable mat without bonding said needle-penetrable mat to said needle-penetrable medium.

15. The method of claim 13, further comprising the steps of:

depositing a plurality of additional fibrous layers on said first fibrous layer;

repeatedly driving said plurality of felting needles into said first fibrous layer and into said plurality of additional fibrous layers to join them together.

16. The method of claim 13, further comprising the steps of:

stacking a plurality of additional fiber layers on said first fiber layer;

repeatedly driving said plurality of felting needles into said first fibrous layer and into said plurality of additional fibrous layers to join them together; when it is desired to incorporate at least some of the additional fiber layers, it is not necessary to drive the plurality of felting needles all the way through the plurality of additional fiber layers.

17. The method of claim 13 wherein said step of removably securing said needle-penetratable spacer to said base further comprises the step of clamping said needle-penetratable spacer to said base.

18. The method of claim 13 wherein said needle-penetrable medium is permanently affixed to said base.

19. The method of claim 13 wherein said needle-penetrable medium comprises bristles of a brush permanently affixed to said base.

20. The method of claim 13 wherein said needle-penetrable gasket is a fibrous gasket.

21. The method of claim 13, wherein the step of removably securing said needle-penetratable spacer to said base further comprises the step of placing said needle-penetratable spacer over a plurality of pins of said base outside of said planar surface.

22. The method of claim 13, further comprising the step of removably securing at least one additional needle-penetratable spacer overlying said surface to said rotary needling support outboard of said surface.

23. A rotary needling method comprising the steps of:

stacking a fibrous mat on a needle-penetratable media mounted on a base, said needle-penetratable media defining a planar surface and having a plurality of brush bristles;

placing said fibrous mat over said plurality of pins of said base outside of said planar surface to removably secure and clamp said fibrous mat to said base outside of said planar surface;

rotating said base about an axis of rotation perpendicular to said planar surface;

depositing at least a first fibrous layer on said fibrous mat;

repeatedly driving said plurality of felting needles into said first fibrous layer and said fibrous mat to bond them together;

stacking a plurality of additional fiber layers on said first fiber layer, one or more layers being added at a time;

repeatedly driving said plurality of felting needles into said first fibrous layer and said at least one additional fibrous layer to bond them together;

driving said plurality of felting needles repeatedly into said plurality of additional fiber layers to bond said plurality of additional fiber layers one or more at a time without driving said plurality of felting needles into a needle-penetrable medium when only some of said additional fiber layers are bonded;

after these bonds are completed, removing the fibrous mat, the first fibrous layer and the plurality of additional fibrous layers from the needle-penetratable media.