Method for making light and stiff panels and structures using natural fiber composites

Abstract

Method for making light and stiff panels and structures using natural fiber composites. An improved composite material utilized in musical instruments. Bio-based industrial fiber such as flax, cellulose, hemp, bamboo, and jute combined with a core material such as foam, aramid honeycomb, carbon fiber or balsa wood, and a resin, serves as a replacement to traditional tone wood. In another embodiment, the bio-based composite has no core material but simply layers of fabric with resin. Another embodiment finds layers of the woven bio-composite as the core between outside layers of carbon fiber or aramid. In the case of a string instrument, bio-composites can be used to make a substantially hollow unitary body, neck and head as well as soundboard. Another usage is for the bracing material of the soundboard. In fact in its various forms, bio-composite can effectively replace all the old growth wood currently used.

Claims

1. A sound board useful in association with an acoustic musical instrument, the soundboard comprising: at least one surface layer including a plurality of only unidirectional filaments made from a natural material and a resin matrix exterior, and wherein the at least one surface layer does not include any woven material; and a middle core layer.

2. The sound board of claim 1, wherein the middle core layer includes an aramid paper honeycomb core material.

3. A sound board useful in association with an acoustic musical instrument, the soundboard comprising: at least one layer of hybrid material including a plurality of only unidirectional natural fiber filaments and synthetic filaments, and wherein the at least one layer does not include any woven material; a resin matrix exterior; and a middle core material.

4. The sound board of claim 1, wherein the middle core layer includes a wood veneer core material.

5. The sound board of claim 3 and wherein the middle core layer includes a wood veneer material.

6. The sound board of claim 1, wherein filaments are continuous.

7. The sound board of claim 1, wherein the middle core layer includes a foam core material.

8. The sound board of claim 1, wherein the middle core layer includes an end-grain balsa core material.

9. A string instrument comprising: an instrument body; and a sound board including: at least one surface layer having a plurality of only unidirectional filaments made from a natural material and a resin matrix exterior, and wherein the at least one surface layer does not include any woven material; and a middle core layer.

10. The sound board of claim 1 further comprising a bracing support assembly including: a support structure having a bio-composite material; and a resin matrix.

11. The sound board of claim 10 wherein the support structure has a substantially T-shaped cross-sectional profile, and wherein the bio-composite material includes at least one of a woven material and a uni-directional material.

12. The sound board of claim 10 wherein the support structure has a substantially square cross-sectional profile, and wherein the bio-composite material includes at least one of a woven material and a uni-directional material.

13. The sound board of claim 10 wherein the support structure has a substantially rectangular cross-sectional profile, and wherein the bio-composite material includes at least one of a woven material and a uni-directional material.

14. The sound board of claim 3 wherein the middle core layer includes an aramid paper honeycomb core material.

15. The soundboard of claim 3 wherein the middle core is a foam core material.

16. The string instrument of claim 9, wherein the middle core layer includes an aramid paper honeycomb core material.

17. The string instrument of claim 9, wherein the middle core layer includes a wood veneer core material.

18. The string instrument of claim 9, wherein the middle core layer includes a foam core material.

19. The string instrument of claim 9, wherein the middle core layer includes an end-grain balsa core material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the present invention may be more clearly ascertained, some embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 is perspective view of a conventional stringed instrument;

(3) FIG. 2 is a chart showing dampening on the x axis and stiffness on the y axis;

(4) FIG. 3 is an illustration showing the effect of string vibration on the soundboard of one embodiment of the present invention;

(5) FIG. 4 is a cross-sectional view of a cylindrical structure in accordance with some embodiments of this invention;

(6) FIG. 5 is a cross-sectional view of an exemplary soundboard in accordance with some embodiments of this invention;

(7) FIG. 6 is a cross-sectional view of an alternative exemplary soundboard in accordance with other embodiments of this invention;

(8) FIG. 7 is a cross-sectional view of an exemplary string instrument body in accordance with some embodiments of this invention;

(9) FIG. 8 includes cross-sectional views of an exemplary bridge plate in accordance with some embodiments of this invention; and

(10) FIG. 9 includes cross-sectional views of alternative exemplary bracing profiles in accordance with various embodiments of this invention.

DETAILED DESCRIPTION

(11) The present invention will now be described in detail with reference to several embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well-known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. The features and advantages of the present invention may be better understood with reference to the drawings and discussions that follow.

(12) Aspects, features and advantages of exemplary embodiments of the present invention will become better understood with regard to the following description in connection with the accompanying drawing(s). It should be apparent to those skilled in the art that the described embodiments of the present invention provided herein are illustrative only and not limiting, having been presented by way of example only. All features disclosed in this description may be replaced by alternative features serving the same or similar purpose, unless expressly stated otherwise. Therefore, numerous other embodiments of the modifications thereof are contemplated as falling within the scope of the present invention as defined herein and equivalents thereto. Hence, use of absolute and/or sequential terms, such as, for example, “will,” “will not,” “shall,” “shall not,” “must,” “must not,” “first,” “initially,” “next,” “subsequently,” “before,” “after,” “lastly,” and “finally,” are not meant to limit the scope of the present invention as the embodiments disclosed herein are merely exemplary.

(13) Referring to FIG. 2, this chart illustrates notably, the high dampening qualities of both wood and natural fiber composites on one dimension and the relatively high tensile modulus of natural fiber composites as compared with wood. Carbon fiber composites have relatively low dampening and exceptionally high tensile modulus. Combined with a core material such as middle layer 530, the thickness becomes too thin to be practical in manufacturing

(14) FIG. 3, is a graphical representation of vibration damping and illustrates the effect of string vibration on soundboards of some embodiments of the present invention.

(15) Referring to the cross-sectional view of FIG. 4, in some embodiments, a cylindrical structure such as tube 400 includes top layer 410, middle layer 420, and bottom layer 430. Top layer 410 is made of one or more layers of uni-directional or bi-directional continuous natural fiber such as cotton, flax, cellulose, sisal, ramie, hemp, and Jute, approximately 0.05 mm-0.3 mm approximately 50-250 gsm. Middle layer 420 is made of a core material such as foam, balsa, cork, birch plywood, cardboard, laminate bulker, aluminum and composite honeycomb such as Nomex manufactured by DuPont of Wilmington, Del. These cores can range in thickness from approximately 2-10 mm. Tube 400 is useful for construction the soundboard of string instruments such as guitars, ukuleles, and violins. Bottom layer 430 is made of a least one layer of uni-directional and/or bi-directional bast-based fiber such as flax, hemp, and Jute, approximately 0.1 mm-0.5 mm approximately 50-250 gsm. Tube 400 can also be used to construct the shells of acoustic instruments such as drums. Other suitable natural fiber materials include recycled paper products, recycled wood products, and other suitable bio materials known to one skilled in the art.

(16) Referring to the cross-sectional view of FIG. 5, an exemplary embodiment of a soundboard includes a sandwich 500 includes top layer 510, middle layer 520, and bottom layer 530. Top layer 510 is made of one or more layers of uni-directional or bi-directional continuous natural fiber such as flax, cellulose, sisal, ramie, hemp, and Jute, approximately 0.05 mm-0.3 mm approximately 50-250 gsm. Middle layer 520 is made of a core material such as foam, balsa, cork, birch plywood, aluminum and composite honeycomb in a range of thickness approximately 1.5 mm-5 mm. Sandwich 500 is useful for construction the soundboard of string instruments such as guitars, ukuleles, and violins. Bottom layer 530 is made of a least one layer of uni-directional and/or bi-directional bast-based fiber such as flax, hemp, kenaf, sisal, ramie and Jute, approximately 0.1 mm-0.5 mm approximately 50-250 gsm. Sandwich 500 can also be used to construct the shells of acoustic instruments such as drums. In some embodiments, top layer 510 includes two uni-directional layers each about 50-250 gsm in thickness.

(17) In some embodiments, top layer and bottom layer 510 and 530 can be made of preimpregnated composite with suitable adhesive such as epoxy, bio-based epoxy, polyester, vinylester, hemicellulose, sap, sugar resin and phenolic and/or any other natural and/or synthetic compounds known.

(18) In another embodiment, top layer and bottom layer 510 and 530 can be made using suitable liquid adhesive applied directly to the dry fabric by brush injection and/or vacuum infused.

(19) In yet another embodiment, top layer and bottom layer 510 and 530 can be made using a sheet molding compound and/or film adhesive applied directly to the dry fabric. It is also possible for a top layer 510 to be prepreg and a bottom layer 530 to be a dry fabric layer with suitable adhesive.

(20) Top layer and bottom layer 510 and 530 can be adhered with the middle layer(s) 520 under compression at approximately 10-100 psi using for example a vacuum, compression press, autoclave and/or continuous lamination as well processing at a temperature range of approximately 70-250 degrees Fahrenheit (“F”).

(21) Middle core layer 520, as is known to people familiar in the art of composites, adds exponential specific tensile modulus proportional to thickness.

(22) Smaller Instruments and/or Lower String Tension

(23) In some smaller instruments such as ukuleles and classical guitars with lower tension nylon strings, thinner middle layer 520 may be used with a range in thickness of approximately 1 mm-2 mm and top layer and bottom layer 510 and 530 with a range of thickness from approximately 0.05 mm-0.2 mm.

(24) Referring to the cross-sectional view FIG. 6, in yet another embodiment of the invention, a soundboard includes a sandwich 600 includes top layer 610, middle layer 620, and bottom layer 630. Top layer 610 is made of one or more layers of uni-directional, bi-directional, and/or discontinuous and/or continuous natural fiber such as flax, cellulose, sisal, ramie, hemp, and Jute, approximately 0.05 mm-0.3 mm approximately 50-250 gsm laminated with one or more layers of uni-directional and/or bi-directional aramid, Innegra, carbon fiber, or fiberglass, approximately 0.05 mm-0.3 mm approximately 50-250 gsm. Middle layer 620 is made of a core material such as foam, balsa, cork, birch plywood, aluminum and composite honeycomb in a range of thickness approximately 1 mm-7 mm. Sandwich 600 is useful for construction the soundboard of musical instruments such as guitars, ukuleles, pianos and violins. Bottom layer 630 is made of one layer of uni-directional and/or bi-directional bast-based fiber such as flax, hemp, and Jute, approximately 0.1 mm-0.5 mm approximately 50-250 gsm and one or more layers of uni-directional and/or bi-directional aramid, Innegra, carbon fiber, or fiberglass, approximately 0.05 mm-0.3 mm approximately 50-250 gsm. Sandwich 600 can also be used to construct the shells of acoustic instruments such as drums.

(25) In some embodiments, the soundboard includes a hybrid weave with natural fibers and carbon fiber woven at about 0-90 degrees to each other. It is also possible for the hybrid weave to include natural fibers and/or synthetic fibers arranged in substantially randomized directions.

(26) In some embodiments, top layer and bottom layer 610 and 630 can be made of preimpregnated composite with suitable adhesive such as epoxy, bio-based epoxy, polyester, vinylester, hemicellulose, sugar resin and phenolic.

(27) In other embodiments, top layer and bottom layer 610 and 630 can be made using suitable liquid adhesive applied directly to the dry fabric by brush injection and/or vacuum infused.

(28) In yet another embodiment, top layer and bottom layer 610 and 630 can be made using a sheet molding compound and/or film adhesive applied directly to the dry fabric. It is also possible for a top layer 610 to be prepreg and a bottom layer 630 to be a dry fabric layer with suitable adhesive.

(29) Top layer and bottom layer 610 and 630 can be adhered with the middle layer(s) 620 under compression at approximately 10-100 psi using for example a vacuum, compression press, autoclave and/or continuous lamination as well processing at a temperature range of approximately 70-250 F.

(30) Middle core layer 620, as is known to people familiar in the art of composites, adds exponential specific tensile modulus proportional to thickness.

(31) Referring to FIG. 7 which includes cross-sectional views of an exemplary string instrument of the present invention, cross section of body 700 includes top layer 710, middle layer 720, and bottom layer 730. Top layer 710 is of one or more layers of uni-directional or bi-directional bast-based fiber such as such as flax, cellulose, sisal, ramie, hemp, and Jute, approximately 0.05 mm-0.3 mm approximately 50-250 gsm. Middle layer 720 is made of a core material such as foam, cork, balsa, honeycomb in a range of thickness approximately 0.3 mm-7 mm. Middle layer 720 can also be made of one of more layers of biocomposite Cross-section of body 700 is useful for construction of the body of string instruments such as guitars, ukuleles, and violins. Bottom layer 730 is made of a least one layer of uni-directional or bi-directional bast-based fiber such as flax, hemp, and Jute, approximately 0.3 mm-2 mm approximately 50-250 gsm.

(32) In some embodiments, top layer and bottom layer 710 and 730 can be made of pre-impregnated composite with suitable adhesive such as epoxy, bio-based epoxy, polyester, vinylester, hemicellulose, sugar resin and phenolic.

(33) In another embodiment, top layer and bottom layer 710 and 730 can be made of liquid resin applied directly to the dry fabric brush injected or infused.

(34) It is also possible for a top layer 710 to be prepreg and a bottom layer 730 to be a dry fabric layer with suitable adhesive.

(35) Top layer and bottom layer 710 and 730 are combined with middle layer(s) 720 under compression at approximately 10-100 psi using for example a vacuum, compression press, and/or continuous lamination as well processing at a temperature range of approximately 70-250 f.

(36) Referring now to FIG. 8, which includes cross-sectional views of an exemplary bridge plate in accordance with some embodiments of this invention, the bridge plate includes the top layer 810 and bottom layer 830 are comprised one or more layers of unidirectional and/or bi-directional bio-based approximately 40-300 gsm fabric. Wherein middle layer 820 is comprised of core material from approximately 1-10 mm thick.

(37) In another embodiment, the top and bottom layers are comprised one or more layers of uni-directional and/or bi-directional aramid and one or more layers of uni-directional and/or bi-directional bio-based fabric.

(38) Similarly, another embodiment, the top and bottom layers are comprised one or more layers of uni-directional and/or bi-directional carbon fiber and one or more layers of uni-directional and/or bi-directional bio-based fabric.

(39) The bridge plate 800 can be mounted to the underside of the soundboard 840 where the strings are mounted via the bridge.

(40) This arrangement adds stiffness to the structure proportional to the geometry and thickness of the bridge plate.

(41) The density of the bridge plate has impact on the timber and warmth of the acoustic tone. Biocomposite enables very low mass bridge plates and thus warm eq.

(42) FIG. 9 includes cross-sectional views of alternative exemplary bracing profiles for additional embodiments of the present invention. Referring to bracing assembly 900a, two longitudinally oriented biocomposite tubes and/or rods and/or molded and/or tube/rod subassemblies running the length of the sound box and/or entire length of body including the neck and head. Also shown, are two tubes and/or rods and/or molded components and/or tube/rod subassemblies latitudinal oriented. In other embodiments bracing assembly 900a utilizes a single to a multitude of biocomposite tubes and/or rods and/or molded bracing components and/or tube/rod subassemblies.

(43) Bracing profile cross section 900b, can be a rod made of one or more layers of biocomposite approximately 100 gsm-500 gsm and ranging in size from approximately 2-10 mm square. In another embodiment the rod is rectangular wherein length is approximately 2 mm-8 mm and width approximately 3-12 mm. Other bracing profiles would also effective including Trianglar, T-bracket, L-bracket, half-moon, elliptical, polygonal, or any other suitable profile designs known to one skilled in the mechanical arts. In addition, these bracing profiles may be perforated to further increase their strength to weight ratio. Perforations may be molded, punched, drilled, laser-cut, or otherwise created using methods known to one skilled in the art.

(44) Bracing profile cross section 900c, is a tube made of one or more layers of biocomposite approximately 100 gsm-500 gsm and ranging in size from approximately 2-10 mm square. In another embodiment the tube is rectangular wherein length is approximately 2 mm-8 mm and width approximately 3-12 mm.

(45) Bracing profile cross section 900d, is a I-beam made of one or more layers of biocomposite approximately 100 gsm-500 gsm and ranging in size from approximately 2-12 mm.

(46) Bracing profile cross section 900e, is a tube made of one or more layers of biocomposite approximately 100 gsm-500 gsm and ranging in size from approximately 2-10 mm square. In another embodiment the tube is rectangular wherein length is approximately 2 mm-8 mm and width approximately 3-12 mm.

(47) In some embodiments, cross sections 900a-900e may be tapered wherein the outer edges are substantially thinner than the center. The taper distance ranges from approximately 0-50 mm.

(48) There are various methods to manufacture these tubes, rods and assemblies including compression molding, wrap-rolling, bladder-molding, filament winding and pultrusion. In other embodiments the bracing can be molded as a substantially hollow 3D form. For example an x-brace for a steel string acoustic guitar—thereby eliminating joints, reducing weight and production complexity.

(49) Bracing profiles as shown in 900b-900c and as oriented in assembly 900a, can add substantial stiffness to the structure depending on geometry and thickness.

(50) While the above described structures and methods have been exemplified using the construction of stringed musical instruments, many of these structures and methods can be also used for the manufacture of other acoustical musical instruments such as drums. In addition, these structures and methods can also be adapted for manufacturing of other products such as furniture, hand tools, kitchen utensils and storage containers.

(51) While this invention has been described in terms of several embodiments, there are alterations, modifications, permutations, and substitute equivalents, which fall within the scope of this invention. Although sub-section titles have been provided to aid in the description of the invention, these titles are merely illustrative and are not intended to limit the scope of the present invention.

(52) It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, modifications, permutations, and substitute equivalents as fall within the true spirit and scope of the present invention.