US1950621A - Resonant acoustical article of manufacture - Google Patents

Description

Patented Mar. 13, 1934 PATENT OFFICE.

RESONANT ACOUSTICAL ARTICLE OF MANUFACTURE Waldo G. Morse, Yonkers, N. Y.

No Drawing. Application November 20, 1930, Serial No. 497,055

10 Claims.

My invention relates to an article of manu facture or composition of matter useful in structures designed for or employed in the production, re-production, amplification, modification or perpetuation of sound, tones, tonal qualities or vibrations causing, produced by or accompanying the same and for various other uses, and the process of making the same. It has for its objects the production of such material or article of manufacture, and its employment in the structures named and in various structures where resonance or tone control is desired.

A further object is the production of articles useful for various purposes made from or out 1 of said article of manufacture, useful because of their lightness, durability, strength, ease of handling and adaptability to varying requirements as to character and appearance.

In the past problems of resonance have been treated as the result of mass vibration. As distinguished from that I have observed that properties of resonance are to a large degree dependent on molecular motion within the body of the material in conjunction with or independent of mass motion; in other words, the elastic reactions of a multitude of minute elements under tension.

I have also observed that structures comprising minute spherical or rounded particles are more likely to be highly and pleasantly resonant than angular or abrazed materials. It has been noted for example in old violins, famous for their tone, that as seen under the microscope the wood seems to have worked itself into somewhat rounded particles.

A long series of experiments along these theoretical lines have led me to devise a resonant material consisting in general of minute, hard rounded particles as the primary ingredient, With an elastic binder modified by the addition of fine flakes or splinters of fibrous material to soften the resonance to any degree desired. The molecular tensions in the ingredients and the myriad of stresses or tensions caused by the hardening or shrinking of the binder material produce unusual resonanting qualities. In any case, whatever the theoretical cause, the materials so produced have been found to give excellent results in a large number of experimental structures.

In carrying out my invention I preferably use marl to supply the minute spherical or rounded particles, oat hulls for the resilient or fibrous material, and rubber or glue for the binder.

The binder may be the common flake or ground glue of any desired quality, white French cabinet glue, casein glue, blood or albumen glue, or any other variety of glue capable of hardening sufiicicntly and which contracts upon cooling and drying or either, or rubber hardened or vulcanized by any well known means.

The marl is of the type found in nature precipitated from solution in the waters of lakes and ponds. Such marl is precipitated carbonate of lime and consists of detached minute or microscopic globes or spheres. It is preferably reduced from its plastic moist form as found in nature and caked and dried and then abraided to the form of a powder composed of its ultimate globular molecules or particles as precipitated, having the same free and unattached one from the other, all shells and other extraneous substances having been first sifted out. Where the marl is suiiiciently free from admixture or is mixed chiefly with a proportion of fine clay as sometimes is the case, it is practicable to use the material without drying or grinding. Such marl is composed of globular particles of microscopic size and is to be distinguished from materials composed of angular, irregular, prismatic or abraded structures. Most mineral or earthy substances, as Well as materials made from sea shells, such as chalk, for example, have a crystalline or angular structure. Materials commonly employed as fillers in the making of composite materials, such as sands, whiting, infusorial earth, ground rotten stone, lime-stone and the like are produced by the abrasion of massive materials or the grinding of hard solid substances. On the contrary, marl as employed by me is composed of free and uncemented spherical particles and may be softened and put into a plastic form or suspension by the use of water and without any grinding, therefore being different from baked clay or pottery. Other spherical or oval particles of microscopic or minute size and of requisite hardness are within the scope of my invention whether of animal origin as is the case with marl, or of vegetable origin as in the case of minute spores or seeds which also I employ.

The oat hulls to be employed preferably, are ground or broken up longitudinally into slivers of appreciable length and accordingly take the form of stifi pointed splinters or particles slightly curved or bowed and slightly concaveconvex and having the characteristic silicious coating upon the convex or outer sides of the hulls with the material growing softer and more fibrous as the cellulose structure of the hull grows more and more predominant toward its inner surface.

All meal, starch, gluten and the like which are found in the kernels of oats should be separated out or are eliminated and discarded before use. It is possible to use the hulls in their original form, as they are discarded in the production of meal, and without re-grinding. The hulls of wheat, rye, barley, corn, rice or other grains, may be used separately or blended with oat hulls or each other in structures of varying sizes or forms to secure diverse effects, though I prefer those of oats. Also splinters of bamboo, ivory, bone, nut shells, wood or the like comparable in size and shape to grain hulls may be used; such other materials needing not of necessity to be pointed or concavo-convex to produce their several characteristic results. The structure of corn cobs or similar material is entirely different from that of oat hulls or the hulls of other grains and from splinters as above described and ground corn cobs would be useless for the purposes indicated in this specification. Wheat and other bran likewise is too fine to accomplish the desired results and wholly unsuited to the purposes sought. Bran comes from an inner coating surrounding the kernel of grain and is distinct from the hull. The reason for employing oat hulls or other stiff, tough and resilient material is that slivers of such material furnish supports to the binding material, of such nature, that strains or tensions resulting from the contraction of the binder put both the binder and such hulls or like material under stress. The oat hulls and other specified materials are still and vibrant and in that respect serve a different purpose and perform a different function from any served or performed through the employment of a material such as flock or cotton or other soft absorbent or yielding material. The employment of such material as grain hulls and the like above described in conjunction with a binder as distinguished from a material which simply forms an inert filler constitute one phase of means employed in carrying out my invention. 7

Any stiff, fibrous or amorphous material in appreciable lengths, of size in proper relation to the size of the particles of marl or the like, and resilience of proper co-efiicient to the strain and contraction and tensile strength of the binder and sufficient to produce desired molecular tension in the mass and to which the cement or binder to be employed will adhere, may be used. Binders other than glue or rubber may be used, but it is essential that the binder and the fixed material employed be such as are in proper relation of size, strength and nature and take or adhere together as do marl, oat hulls and glue, and do not crack apart. The particular types described as preferred are found adapted to phonograph and radio reproducers and diaphragms and to violins.

The glue rubber or other similar binder is used in amounts exceeding those required to produce cardboard, papier-mtch and the like. In my construction, the binding material is so in excess, as compared with cardboard or papiermach, that as it cools or dries and contracts under atmospheric or mechanical pressure as the case may be, the whole mass will solidify without the forming of dominant air spaces or loose contacts and so will produce a resonant structure under internal tension, stress or strain by reason of the contraction of the binding material around and between the particles or pieces of material contained therein and surrounded thereby. All of the glues and other materials specified are known to shrink or contract in setting and so are adapted to produce the requisite strain or molecular tension in the solidified mass. Glues, rubbers, gums and resins possess this feature in marked degree.

In carrying out my invention employing the preferred forms of available materials as above set forth for the purposes primarily in view, that is to say, the production of a composite resonant substance under molecular internal stress or tension, the procedure is as follows:

Common glue is hydrated and dissolved in the usual manner. Marl abraded into a powder or softened into a paste by the addition of water is then added and thoroughly stirred into a un'form mixture, the entire mass being kept hot. Proportions varying from one of glue to one of marl and up to six or more of marl, dry measure, have been found available for the production of different types of the material and varying results.

Into the hot mass so formed and hydrated to about the consistency of cream, are then stirred dry re-ground or comminuted oat hulls varying from a small quantity say one-half in bulk that of the combined glue and marl to a quantity several times such bulk, according to the character of the product sought to be formed.

The material so compounded is spread upon forms or placed in molds or pressed into shape in any well known manner, and allowed to set, cool and harden, being thereafter removed for finishing and use.

It may be applied by means of a brush or knife or the like and allowed to harden under atmospheric pressure and one or more coats may be so applied, or it may be formed in molds or otherwise shaped.

When compounded the material may be reserved for use and softened by moisture and heat or may be broken up for dry pressing or forming as and when desired.

The nature and behavior of the materials during manufacture and hardening is such that the particles of marl remain rigid while the glue or rubber contracts greatly upon cooling, drying or setting. By such contraction the entire mass is put under great molecular strain or tension and a very tough, refractory, resilient and resonant product results. When the proportion of marl is small, the binder is predominant in the mixture. When larger proportions of marl are employed, the product becomes horny but remains massive, while the addition of still larger proportions of marl causes the material to set with small interstices or air spaces throughout the mass.

Such characteristic results occur and persist as to the drying binder about the particles of marl or other described equivalent in the material as combined with oat hulls or independently thereof, and are described separately for that reason.

By such means, I have formed blocks and sheets of material and have fabricated phonograph amplifiers, horns, tone arms, sound boxes and diaphragms and also radio horns all of the same in various sizes, shapes and of different di- Ill mensions and have made violins and other things.

. desirable tone. roidal, oval or rounded grains or particles are I have learned that the resulting product and the characteristic resonance of the material and the tone quality obtained through its use may be varied within wide limits through variations in the quality of the binder employed and the proportions of binder and marl used and also that further and other modifications of the character of the material or article produced and the resonance of the same may be secured through the employment of smaller or larger proportions of oat hulls or variations within certain limits in the size to which they are comminuted.

By using glue and marl hydrated, barely sufliciently to maintain fluidity when heated to the boiling point, and using a larger quantity of glue and marl in proportion to the quantity of hulls, a very hard composition may be produced characterized by a high pitch and great resonance when intonated, while by using a thinner glue or one containing a larger proportion of water, the product obtained when cooled and dried may show small interstices between the hulls or other material with a lower characteristic resonance.

Generally speaking the mixture of glue and marl set under atmospheric pressure attains its greatest refractory point when the dried and hardened glue is just suilicient to fill completely 80' the interstices among the particles of marl, say one of glue and two of marl, dry weight strength and high tonal pitch declines from that point as marl is added. When mechanical pressure is employed, smaller proportions of glue or other binder should be used. Like eiiects result from similar employment of rubber.

With a proper admixture of glue or rubber and marl, the preferred quantity of oat hulls or their said equivalents to secure such maximum 40' termination according to the sizes of the grains 45 of marl or other spherical or rounded element and the pieces of the cat hulls or other like substance or substances and the pressure applied during setting.

The essential characteristic of marl which renders it available for the uses described is the rounded or globular shape of its particles. Such characteristic as specified above is exceedingly advantageous in securing resonance and Other masses of spherical sphecapable of producing similar results and various types of tone or timbre, when the grains are of suitable small or microscopic size and adapted to coact with the slivered or like material formed into the mass as for example precipitates generally, minute seeds or grains, spores, pollen and other vegetable products natural or artificially produced single or combined and of suitable size and physical characteristics.

The characteristic tone of the completed article when vibrating, tends to be lowered and softened as the proportion of oat hulls or the like is increased and the tendency to a continuation of any resonant movement induced in the acteristics are of the greatest value, in sound producing or recording or re-producing instruments or devices.

In practice, l have stained and varnished articles produced, for the purposes of preservation and decoration, and any results desired may be obtained by such methods.

indicated, any type of glue may be employed and any temper oi the same or of gelatine glue, may be used.

I have produced similar results by the use of gum shellack, gum copal, gum and other gums, and resins, alone or in combination, having rendered the same plastic by heat, and mixed them with marl and the like and oat hulls and the like while hot and then allowed the mixture to cool.

Likewise I have produced most excellent resuits through the employment of rubber as a binder, the marl and oat hulls and their equivalent being mixed into the rubber while plastic or in the course of the production of vulcanized or hard rubber by usual methods and then the mass vulcanized by application of heat. An alternative method is to mix the marl and cat hulls or their equivalent with latex and then vulcanize the mixture by use of well known means. Also it is apparent that for certain types of vibration and resonance soft rubber is preferable. Any available commercial binder or composition be used in place of the glue gum or rubber, but the rubber is highly durable and resistant to heat and moisture. The material resulting from the use of heated gums or the like must be shaped or molded, as it cannot be applied with a brush, but these may be softened by a solvent where available, into an enamel or varnish and then spread either cold or further softened by heat, any excess of solvent being driven off thereafter if need be, by reheating. Also any commercial product or Japan may be substitute for shellack.

By cooling the material under pressure, a smaller proportion of binder and larger proportion of marl or the like and hulls or the like may be used in producing a dense material or limiting the air spaces, the pressure hold ng the marl or the like and oat hulls or their equivalent in closer relation so that a smaller quantity of glue or binder will produce a substantially dense mass when cooled and dried or hardened.

The resonant properties of the composition are due to the contraction of the glue or the like upon hardening which puts the whole mass of the material when hardened in a state of molecular tension, stress or strain, such as is always conducive to resonance in any material, while the stiffness or rigidity of the hulls or the like adds to the resonance and counteracts any tendency to warping.

It has become evident that variation in the timbre of a resonant body, such as I have described, may be secured by means of successive coatings varying in composition from clear glue or rubber or the like grading through various degrees to a mixture carrying preponderant quantities of such inert material, the same to be coated or brushed on to articles previously made from the material herein described, all in any pro-determined or desired manner.

Such additional coatings may be placed upon one or both sides of an article manufactured from the material specified, and successive layers may be added of varying composition and resonant qualities as may be desired or found in practice to yield the best tonal results for the particular purposes desired, all in any predetermined or desired manner. Also, a base of thin wood, veneer or other suitable material may be used, whereon to build up the desired coatings.

In compounding my material the elements are mixed so that they are intimately and uniformly distributed together throughout the entire mass and in practice it is possible to attain approximate uniformity of mixture. For various uses, however, it is desirable that various layers or strata of the mass should contain a greater or less proportion of one or the other of the ingredients, for example, greater proportions of oat hulls or other like material may be used in a middle layer of a sheet to be formed While greater proportions of glue or other binder and of marl or the like are employed in the mixture on either side. Or one side of a sheet may be made to vary from the other, or one section oi a sheet or portion of a block may be made to vary from another or various parts may be made to difier among themselves as desired for the accomplishment of various useful purposes of tonal quality Within the charac-.

teristics of the material described.

In accordance with the provisions of the patent statutes I have described the principle of my invention together with the material or apparatus which I now consider to represent the best embodiment thereof, but I desire it understood that my invention is not confined to the particular material or processes herein shown and described, the same being merely illustrative, and that the invention can be carried out in other ways without departing from the spirit of my invention, and therefore, I claim broadly the right to employ all equivalent compositions coming within the scope of the appended claims.

The present application is a continuation in part of Serial Number 168,230 filed February 14, 1927.

Having now described my invention, what I claim and desire to secure by Letters Patent 1. A highly resonant acoustical article of manufacture comprising minute rounded particles, slivers of resilient particles, and a binder which contrasts in setting, adhering to and occupying the space between said particles.

2. A highly resonant acoustical article of manufacture comprising minute rounded particles, slivers of resilient organic particles, and an elastic binder therebetween adhering thereto.

3. A highly resonant acoustical article of manufacture comprising marl, slivers of organic resilient particles, and a binder capable of adhering thereto.

4. A highly resonant acoustical article of manufacture comprising marl, comminuted resilient particles, and a binder which contracts in setting adhering thereto.

5. A highly resonant acoustical article of manufacture comprising marl, comminuted oat hulls, and a binder which contracts in setting, adhering thereto.

:3. A highly resonant acoustical article of manufacture comprising marl, slivers of resilient organic material, and a resilient binder.

'7. A highly resonant acoustical article of manufacture comprising marl, comminuted oat hulls, and an elastic binder which contracts in setting.

8. A highly resonant acoustical article of manufacture comprising minute rounded particles of precipitated calcium carbonate, slivers of resilient organic material, and a binder adhering thereto which contracts in setting, substantially as shown and described.

9. A highly resonant acoustical article of manufacture comprising marl, comminuted oat hulls, and a binder adhering thereto.

10. A highly resonant acoustical article of manufacture comprising marl, comminuted grain hulls, and a resilient binder adhering thereto.

WALDO G. MORSE.