1. Field of the Invention
This invention relates generally to wind musical instruments, more particularly to the materials and construction of lip-reed wind instruments.
2. Prior Art
The following is a tabulation of some prior art that presently appears relevant:
Jacoby, M., Chemical & Engineering News, “Composite Materials” Volume 82, Number 35 pp 34-39, Aug. 30, 2004
The present invention is directed to the materials and construction of instruments belonging to the lip-reed family of musical instruments wherein the improvements achieve an instrument having enhanced musical qualities as well as superior damage and corrosion resistance. The present invention is also directed to a method of fabrication resulting in an instrument of improved precision qualities.
Modern wind musical instruments played with a bored mouthpiece and excited using vibrations from a player's lips belong to the lip-reed family of wind instruments. The family of lip-reed instruments includes but is not limited to the trumpet, natural trumpet, clarino, bugle, flugelhorn, trombone, alto horn, French horn, baritone, euphonium and tuba.
Prior art lip-reed instruments are typically constructed of a series of interconnected brass-alloy tubular sections, both linear and curving, and may feature a number of valved extensions or a slide mechanism to extend the tubular length of the instrument. Using this arrangement some or all of the pitches of the chromatic scale can be produced allowing for extensive use in varied types of musical composition.
The main pipe of lip-reed instruments plays an important role in the production of musical pitches. The pipe's sidewall serves as a waveguide to contain acoustic waves as they travel longitudinally along the main bore. The waveguide properties of a lip-reed instrument's main pipe allows for the formation of standing waves whose natural frequencies correspond to the fundamental and harmonic tones in timbered musical pitches.
The present invention addresses the materials used to construct lip-reed instruments. As such, it is useful to describe the influence of prior art brass alloy materials on the instrument's acoustic and vibration characteristics. The brass alloy materials play a role in the modal vibration, whereby the instrument takes on a mode shape, or vibration pattern. As an example,
During pitch production, excitation of mode shapes has the potential to enhance the timbre of lip-reed instrument but generally do not because of the brass alloy materials that are typically used. The timbre is undistinguished because the significant mode shape frequencies are lower than the acoustic standing-wave natural frequencies. Hence there is limited cooperation between these two mechanisms during pitch production. A primary reason for the lower mode shape natural frequencies is the low bending stiffness of brass alloy curved sections of the main pipe. The curved sections have a bending stiffness that is lower than the bending stiffness in linear sections and is an area that is strained considerably during mode shape vibration. Another reason for the lower natural frequencies is the high mass of the brass alloy tubular sections, which are forced into motion as part of the mode shape. The high mass combined with the low stiffness of the brass alloy tubing results in an instrument that has inferior timbre qualities.
The growth of corrosion is a significant issue associated with prior art lip-reed instruments constructed of brass alloy. During play, moisture and electrolyte material are transmitted into the bore of the brass alloy tubing which remains in place until the instrument is properly cleaned. This results in corrosion scale growth that impacts the acoustic properties due to the encroachment on the bore cross sectional area. The bore cross sectional area is an important parameter affecting the acoustic standing wave pattern and standing wave natural frequencies. The impact of the corrosion is confirmed by seasoned players who observe that old instruments do not respond like new instruments free from corrosion. Corrosion can also be a structural problem for lip-reed instruments constructed of brass alloy. Brass alloy suffers from red-rot corrosion which results in deterioration of the instrument structure.
Prior art lip-reed instruments are susceptible to structural damage. During operation, instruments are occasionally subject to impact loading due to sudden contact with other objects. The use of brass alloy material renders instruments susceptible to such damage because of its high malleability and low yield stress. Instruments constructed of brass alloy require costly repairs when damage occurs. This is particularly the case for damaged curved sections which require specialized skills and tooling to repair.
Prior art brass-alloy instruments are constructed with a large degree of hand craftsmanship which lends itself to unpredictable geometric variation each time an instrument is fashioned. The construction of the brass-alloy curved sections is an area where a significant degree of production variation can be attributed. The brass-alloy curved sections are fabricated from straight tubing sections which are given the correct bore size using a drawing process. After drawing, the tubing is filled with a solid but bendable core material and the filled tubing is bent around a curved mandrel. During the bending process the core material preserves the volume of the bore. However, the cross section is distorted in an unpredictable manner resulting in acoustical irregularities. This problem is especially apparent in curved tubes with changing cross sectional dimensions as there are no additional operations available to consistently correct the irregular cross section. It is also common during the bending process to hammer the interior of the curved section to preserve a smooth sidewall. This hammering operation results in further variation by unpredictably altering the stiffness properties of the sidewall.
The inconsistent aspects of prior art brass-alloy manufacture result in two problems:
The invention will be more fully understood from the following detailed description, in conjunction with the accompanying figures. The descriptions include five embodiments and associated methods of fabrication. The description of the fabrication is focused on the composite laminate features of the embodiments because existing methods can be used to fabricate the non-laminate features.
The curved section is constructed as a single composite laminate workpiece independently of the remainder of the instrument. The curved section has a constant radius of curvature as well as a tapered bore diameter. This allows a bore mold to be easily removed from the workpiece after a composite fabrication method has been utilized and the composite laminate has cured. Using a bore mold, the curved section is constructed using the vacuum bag molding, filament winding, or resin transfer molding composite fabrication methods. Braided fiber reinforcement sleeves are used in the vacuum bagging and resin transfer molding methods. The sleeves offer a means to reinforce the curved geometry with consistent laminate thickness. After curing, the workpiece is joined with the remainder of the instrument using a butt joint bonded with adhesive.
The curved and linear sections of the second embodiment are fabricated as a single workpiece independently from the remainder of the instrument. The single workpiece construction allows for simplified construction with reduced part count. There are two approaches to manufacturing these sections as a single workpiece.
A first approach for constructing the workpiece is according to the vacuum bagging, resin transfer molding or filament winding composite fabrication methods wherein a bore mold is utilized. The bore mold is constructed of a meltable, dissolvable or otherwise disintegrable material. The bore mold must be constructed of disintegrable materials to allow removal from the workpiece. Materials for the mold include but are not limited to a plaster, a wax, or a eutectic salt. The bore mold is removed by disintegration after the workpiece has cured.
A second approach for constructing the workpiece is according to the bladder molding composite fabrication method. The bladder molding method includes:
The bight section of the third embodiment is constructed independently of the remaining components using the approach described for the first embodiment or the two approaches described for the second embodiment. The curved section is joined with the linear tubes using a butt type joint bonded with adhesive. The linear tubes of the third embodiment may be constructed of carbon fiber reinforced composite using available methods to construct linear tubing.
The curved and linear sections of the fourth embodiment are fabricated as a single workpiece independently from the remainder of the instrument. The single workpiece allows for simplified construction with reduced part count. To fabricate the workpiece, the vacuum bagging, resin transfer molding, or filament winding composite fabrication methods are utilized wherein a bore mold is covered with resinous and reinforcement material.
The subcomponents of the main pipe are each constructed as a single workpiece apart from the remainder of the instrument. The leadpipe is constructed using the vacuum bagging, resin transfer molding or filament winding composite fabrication methods using a bore mold shown in
Various embodiments of the invention beyond those described herein are contemplated. The carbon fiber reinforced composite laminate can be practically applied to almost any lip-reed instrument commonly used today and further testing is planned to apply these improvements throughout the lip-reed family. A carbon fiber reinforced laminate may be applied to the curved sections and to the main pipe of these instruments to realize improved acoustic qualities. The improvements may also be applied to instruments having no valved extensions or to instruments having a slide mechanism, such as a trombone slide, to tune predetermined pitches.
Various modifications and changes are also contemplated and may be utilized to optimize the vibro-acoustic response of the composite laminate. The stiffness and mass of the composite laminate are important parameters which affect the mode shape natural frequencies. To achieve optimal response, projection and timbre, the laminate thickness and the fiber direction of the laminate will be adjusted. Fiber angles between 0 and 90 degrees away from the bore axis and thicknesses between 0.016 and 0.500 inches will be investigated to achieve optimal vibro-acoustic response. The resins used in composite laminate are also important to the stiffness and damping of the instrument and require optimization. Investigation of several resins is currently planned as well as pre-impregnation of the reinforcement materials with resinous material.
Modifications of the materials used for the mouthpiece, tubular sections, linear tubes, valve casings, pistons, braces, valved extensions and bell are also contemplated. Depending on the outcome of testing these may be composed of a carbon fiber reinforced laminate, brass alloy or other material.
Alternative embodiments of the invention are also contemplated which exploit the benefit of reduced part count offered by the composite laminate construction. The composite laminate construction allows components which were traditionally separate workpieces to be fabricated together as a single workpiece. Of the described embodiments, it is contemplated that the mouthpiece and leadpipe, the bell and hook pipe, the linear tube and bight section, and the lower pipe and knuckle can be made as a single workpiece. Other embodiments will also have a number of components which can be fabricated as a single workpiece.
Embodiments of the present invention utilize a composite laminate having one or more layers of carbon fiber reinforcement as a material to construct the sidewall materials of the wind instrument. Use of carbon fiber reinforced material has several advantages that are explained in the following paragraphs.
Carbon fiber reinforced composite laminate has a high stiffness and a low density compared to the stiffness and mass of brass alloy used in prior art lip-reed instruments. These properties offer an improvement when considering the modal vibration characteristics and the impact on timber and projection qualities. Lip-reed instruments having a main pipe constructed of carbon fiber reinforced composite laminate have higher stiffness and lower mass than prior art brass alloy tubing. Due to this, the mode shapes occur at natural frequencies of higher value compared to a prior art instrument constructed of brass alloy tubing.
Use of carbon fiber reinforced composite laminate is particularly beneficial when applied to curved sections of the instrument's main pipe. The curved sections have inherently lower stiffness than straight sections due to their curved geometry. For this reason the mode shapes have considerable elastic deformation in the curved sections. Lip-reed instruments having curved sections constructed of carbon fiber reinforced composite laminate have significantly higher bending stiffness which results in natural frequencies of higher value compared to brass alloy curved sections. The relatively higher natural frequencies of carbon fiber reinforced instruments improve the instrument's timbre due to better cooperation with acoustic standing waves in the instrument's bore. The mode shape natural frequencies more closely match the natural frequency of the standing waves in the instrument. Due to this, the acoustic radiation coming from the mode shapes cooperates and reinforces the radiation coming from the standing waves. The result is an instrument having better projection and a brilliant timber that is more pleasing to the listener.
The use of carbon fiber reinforced composite laminate for the tubing of lip-reed instruments is superior to brass alloy in terms of corrosion properties. Laminates made of fiber material do not suffer from the galvanic corrosion of brass alloy. Hence the problems of corrosion and scale growth and the associated acoustic and structural degradation are eliminated. This property is also advantageous because it results in an instrument that requires less cleaning and maintenance.
Use of carbon fiber reinforced composite laminate together with the described fabrication methods solves the precision problems that have limited the prior art. Production of composite laminate wind instruments using precision molds achieves smaller geometric tolerances and consistent sidewall stiffness properties. This is particularly beneficial for the curved sections which have precision greatly improved over the prior art. The improvements result in little or no perceptible differences between instruments of common design as well as an enhanced ability to further optimize the instrument design beyond today's designs and standards.
Accordingly, the reader will see that the improvements of the various embodiments offer a superior lip-reed instrument with musical qualities that will be appreciated by players and listeners alike. Furthermore, the invention and associated fabrication method have the additional advantages in that:
Although certain embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims. Thus the scope of the embodiments should be determined by the appended claims and their legal equivalents, rather than by the examples given.
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