US3805662A

US3805662A - Piano hammer

Info

Publication number: US3805662A
Application number: US00276170A
Authority: US
Inventors: F Nishimura; K Yamada
Original assignee: Nippon Gakki Co Ltd
Current assignee: Nippon Gakki Co Ltd
Priority date: 1971-08-04
Filing date: 1972-07-28
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: JPS4825514A; DE2238298A1; GB1366586A

Abstract

Piano hammer having a felt member which has been impregnated with vinyl monomer or a dilute solution thereof with solvent and then subjected to heat or radiation to polymerize and cure said monomer within said felt is disclosed. The polymerized and cured vinyl monomer not only makes the hammer felt durable, strengthening the resistance to wear thereof without becoming any cause of noise generation itself, but also protects the felt member from being affected by moisture, since the fibers of the felt member are covered, or bonded together, by the polymerized vinyl monomer.

Description

United States Patent 1191 Nishimura et a1.

1111 3,805,662 Apr. 23, 1974 1 PIANO HAMMER [75] Inventors: Fumiyoshi Nishimura; Koichi Yamada, both of Hamamatsu, Japan [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsu-shi, Japan [22] Filed: July 28, 1972 [21] Appl. No.: 276,170

[30] Foreign Application Priority Data Aug. 4, 1971 Japan 46-58249 [52 us. c1. 84/254, 84/452 F, 156/250 51 Int. Cl G106 3/18 [58] Field of Search 84/254, 452 P; 156/250;

[56] References Cited UNITED STATES PATENTS 1,374,974 4/1921 Wrozina 84/254 2,357,392 9/1944 Francis 264/6 2,817,574 12/1957 Boeddinghaus 117/140 R 3,296,023 l/l967 Leaderman 1 17/140 R 3,487,429 l2/l969 Johnson 84/254 3,616,031 10/1971 Fleissner 28/73 UX Primary Examiner-Richard B. Wilkinson Assistant Examiner-John F. Gonzales Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT Piano hammer having a felt member which has been impregnated with vinyl monomer or a dilute solution thereof with solvent and then subjected to heat or radiation to polymerize and cure said monomer within said felt is disclosed.

The polymerized and cured vinyl monomer not only makes the hammer felt durable, strengthening the resistance to wear thereof without becoming any cause of noise generation itself, but also protects the felt member from being affected by moisture, since the fibers of the felt member are covered, or bonded together, by the polymerized vinyl monomer.

5 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION The present invention relates to a piano hammer which is long-lasting and non-susceptible to influences from environmental conditions, especially from moisture, and capable of making a sound having constant tone quality and volume.

The tone quality and volume of piano are delicately affected by conditions of string, hammer and sound board. Particularly, the influence from hammer is important. Therefore, the piano hammer should have an excellent structure having high resistance to wear but nevertheless generating no noises, which otherwise might be'when a string is struck by the hammer, and being non-susceptible to influences from environmental conditions. The non-susceptibility to such influences is an indispensable requirement, for avoiding changes of tone quality and volume.

The piano hammer is composed of a hammer head of wood and a striking member of felt (usually high quality woolen felt) securely attached to the hammer head. In the prior art, in order to increase the resistance to wear of the striking member of felt, a solution of thermoplastic polymer (for example, nitrocellulose lacquer, urethane resin and the like) with solvent is applied to the felt member after the felt is attached to the hammer head wooden plate member and before the plate member is cut to each piano hammer. Such a method according to the prior art, however, has the following drawbacks.

First, the use of the above resinous solution requires a great deal of skill for the application of the solution to the felt. The selections of an amount of the solution and a portion of the hammer to which the solution is applied, depending on the tone region to which the hammer is assigned, are difficult and their fluctuation influences the tone quality and volume of piano.

Secondly, the felt member of the prior-art hammer is greatly influenced by the influences from environmental conditions, especially from moisture, and the hardness of the felt striking member, previously adjusted to a predetermined value, becomes changed first at the outer surface thereof and then gradually toward the inner portion thereof, with the result that the tone quality and volume of the piano are adversely influenced.

Thirdly, the prevailing application technique is not efficient.

Fourthly, the most detrimental drawback is that when conventional resinous solution is applied, it is difficult to make the solution penetrate into the inside of the felt due to high molecular weight of resin (high viscosity of the resinous solution) resulting in an unbalance of hardness in the felt is detrimental to the tone quality of piano, That is, the resin applied to the felt is mostly concentrated on the outer surface of the felt, and the hardness at the outer surface becomes too hard, although the overall hardness or durability of the striking member of felt is insufficient. Such concentration of the resin on the outer surface becomes a cause of generating undesirable noises when the hammer strikes the string.

An object of the present invention is to provide a piano hammer which does not have above drawbacks and a method of producing the same.

DESCRIPTION OF THE INVENTION According to the present invention, there is provided a piano hammer having a felt member which has been impregnated with vinyl monomer or a dilute solution thereof with solvent and then subjected to heat or radiation to polymerize and cure said monomer with said felt.

Furthermore, according to the present invention, there is provided a method of producing the above piano hammer in which, after or before each piece of piano hammer is cut out, the felt is impregnated with vinyl monomer or a dilute solution thereof with solvent and then subjected to heat or radiation to polymerize and cure the monomer inside of the felt.

The present method of producing the piano hammer is very efficient and does not require a great deal of skill. Above all, the aforementioned most detrimental drawback, that is the uniform penetration of the resinous material can easily be overcome since the impregnation can be uniformly effected. This is attributed to the use of monomer instead of resin in the impregnating step and to the subsequent polymerization and cure. In the drawing:

FIG. 1 shows a structure of a hammer head plate member and a long felt strip attached to the plate member, the structure being afterwards cut into pieces of piano hammers; and

FIG. 2 is a side elevational view showing a piece of finished piano hammer.

Referring now to the drawing, a long felt strip 1 of wool is first bonded to a hammer head plate member 2 of wood, so that a plurality of piano hammers can be obtained therefrom. The bonded structure of the felt strip 1 and plate member 2 is thereafter cut into plural pieces of piano hammers along the dotted lines 3 shown in FIG. 1.

Each piano hammer 4, as shown in FIG. 2, comprises a hammer head 5 of wood and a striking member 6 of felt such as woolen felt securely connected to the hammer head. The piano hammer 4 is mounted on the end of a shank 7.

According to the present invention, the long felt strip 1 or the striking member 6 of felt is dipped or soaked into a vinyl monomer solution, so that the vinyl monomer can bepolymerized therein. Any vinyl monomer compounds which are liquid at room temperature and- /or soluble in usual solvent may be used in the present invention. Preferred examples are esters of ethylenic unsaturated lower fatty acid such as methacrylic acid ester and methylmethacrylate, and vinylic aromatic hydrocarbon such as styrene and vinyltoluene.

The impregnation with vinyl monomer, and the polymerization and cure of said monomer may be effected by any of the methods well known in the art. For example, the polymerization may be either thermal polymerization, photopolymerization, or radiation-induced polymerization.

- EXAMPLE The hammer felt strip 1, which was attached to the hammer head plate member 2 but not cut to each piano hammer piece as above, was dipped or soaked in the vinyl monomer solution for l to minutes and immediately thereafter subjected to a treatment for preventing the evaporation of the monomer (e.g. enveloping the felt strip in an aluminum foil) and then heated in a hot air dryer at a temperature of 90i5C for 5 hours to polymerize the monomer contained in the hammer felt strip.

After the above treatment, the resulting structure of the felt strip and the hammer head plate member was cut to each piano hammer piece by a well known method.

Unlike the above-described example, the bonded structure of the hammer felt strip 1 and the hammer head plate member 2 may be beforehand cut into a plurality of piano hammer pieces and then such piano hammer pieces may be dipped or soaked in the vinyl monomer solution. However, the first mentioned procedure is more efficient in the mass production of the piano hammers.

The piano hammer thus obtained .was found to contain the polymer uniformly distributed inside of the felt. It was further found that the uniformly distributed polymer greatly elevated the over-all durability of the striking member 6, and that the polymer, which did not concentrate on the outer surface of the striking member as in the prior-art one, did not become a cause of noise generation when the piano hammer struck the string. It was still further found that the striking member containing the polymer was superior in the prevention of the striking member from being affected by moisture. This was because the fibers of the felt were covered or bonded together at the contact points thereof by the polymerized vinyl monomer, that is, the resultant polymer. Repeated quality tests-with the articles produced by the above production method did not show any fluctuation of quality.

Furthermore, weathering tests or tests on weatherresistance (resistances to moisture and dry conditions) were carried out and the tone quality and volume of the piano hammer according to the present invention were compared with those of the prior art. As a result, it was established that the piano hammers of the present invention are superior to those produced by applying resinous material to the outer surface of the piano hammer striking member as in the prior art.

We claim:

1. An improved piano hammer comprising a hammer head and a striking member fastened to said hammer head, said striking member composed of felt fibers bonded together at their points of contact with a vinyl polymer, said vinyl polymer being uniformly distributed throughout said felt fibers, said striking member being substantially moisture resistant. I

2. A piano hammer according to claim 1' in which said vinyl polymer is selected fromv esters of ethylenic unsaturated lower fatty acid and vinylic aromatic hydrocarbon.

3. A piano hammer according to claim 2 in which one of said esters of ethylenic unsaturated lower fatty acid is methacrylic acid ester and said vinylic aromatic hydrocarbon is styrene.

4. In a piano hammer comprising a hammer head and a felt striking member securely attached to the hammer, the improvement wherein said striking member is composed of felt fibers as the sole fibers present, said felt fibers secured and bonded to each other by a vinyl polymer distributed uniformly throughout said felt fibers.

5. A piano hammer according to claim 4 wherein said vinyl polymer is selected from the group consisting of methyl methacrylate, styrene and vinyl toluene.

Claims

2. A piano hammer according to claim 1 in which said vinyl polymer is selected from esters of ethylenic unsaturated lower fatty acid and vinylic aromatic hydrocarbon.
3. A piano hammer according to claim 2 in which one of said esters of ethylenic unsaturated lower fatty acid is methacrylic acid ester and said vinylic aromatic hydrocarbon is styrene.
4. In a piano hammer comprising a hammer head and a felt striking member securely attached to the hammer, the improvement wherein said striking member is composed of felt fibers as the sole fibers present, said felt fibers secured and bonded to each other by a vinyl polymer distributed uniformly throughout said felt fibers.
5. A piano hammer according to claim 4 wherein said vinyl polymer is selected from the group consisting of methyl methacrylate, styrene and vinyl toluene.