EP3025325A1

EP3025325A1 - Method for creating an idiophonic percussion instrument

Info

Publication number: EP3025325A1
Application number: EP14755872.0A
Authority: EP
Inventors: Florent RECOUVREUX
Original assignee: Ederod
Current assignee: Ederod
Priority date: 2013-07-25
Filing date: 2014-07-25
Publication date: 2016-06-01
Also published as: WO2015011424A1; FR3009119A1; FR3009119B1

Abstract

Method for creating an idiophonic percussion instrument of the type consisting of a pressed steel membrane associated with a resonance chamber and divided by shaping into a number of areas, corresponding to musical notes, set in vibration using sticks or the hands, characterized by the following successive steps: - the creation, by pressing, of a steel sheet corresponding to the membrane; - the carburizing of said sheet metal; - the heat treatment of the carburized sheet metal; - the specific shaping of the resonant areas.

Description

METHOD FOR PRODUCING AN IDIOPHONE PERCUSSION INSTRUMENT

DESCRIPTION

Technical area

The present invention relates to a method for producing an idiophone percussion instrument, of the type consisting of a stamped steel membrane associated with a sound box and divided by shaping into several areas, corresponding to musical notes, set in motion. vibration by chopsticks or with the hands.

State of the art

In the prior art, the "steel drum" is known, that is to say a

"Steel drum". It is a melodic idiophone percussion instrument.

Its main structure comes from a "barrel of oil" barrel, the lower flat part of which has been stretched, stamped and worked towards the inside of the barrel, in order to obtain a convex shape.

This convex part is divided by shaping into several resonance areas, whose vibration is obtained by percussion with chopsticks.

More recently, a new family of instruments has appeared, directly inspired by the operation of the "steel drum", but unlike this one, it is designed and adapted to be played directly with the hands. An instrument of this type has been described in International Application No. PCT / EP2009 / 057466 of 16 June 2009.

This instrument has an operating principle similar to "steel drum", that is to say the vibration of a steel membrane. However, it differs in particular form.

It generally consists of an assembly of two diaphragms, made of stamped and machined steel sheet, of concave shape, assembled together. One carries the surface where the different resonance areas are shaped, and the second carries an opening in the bottom. It is assembled at the first to form a sound box.

The essential feature according to the aforementioned patent application consists of a nitriding treatment of the plates used for the constitution of the instrument after the latter have been stamped.

The nitriding treatment mainly makes it possible to considerably harden the sheets already stamped. This hardening of the sheet makes it possible to prevent the inconveniences of un-tuning, as well as to improve the acoustic qualities of said sheet, because of a higher frequency module.

But this method has the disadvantage of being expensive.

Indeed, to achieve, by nitriding treatment, to harden throughout the mass previously stamped sheets, a variable thickness of 0.7 mm to 1.25 mm, the nitriding treatment requires to be applied during a very long period of time. long life, about 100 hours for a sheet of about 1 mm thick. Nitriding treatments are generally used in the context of surface treatments very rarely exceeding 1/10 of a millimeter, because of a very slow penetration factor of nitriding treatment. To carry out more in-depth treatments, nitriding quickly becomes a very energy-intensive process, due to the extremely long exposure times to treatment.

Description of the invention

The object of the present invention is to overcome these drawbacks and concerns for this purpose a method for producing an idiophone percussion instrument, of the type consisting of a stamped steel membrane associated with a sound box and divided by forming into several areas, corresponding to musical notes, vibrated by chopsticks or with the hands, characterized by the following successive steps:

forming by stamping a sheet of steel corresponding to the membrane;

carburising said sheet;

specific shaping of the resonance areas.

The object of the present patent therefore lies in a cementation treatment of previously shaped sheets, in particular by embossing or stamping, in order to reinforce the toughness of the sheet, with two main results which are: better holding to prevent inconvenience of un-tuning the instrument, as well as significantly better acoustic qualities. Indeed, carbon is the element that has the greatest influence on the properties of steel. Increasing the carbon content increases hardness, breaking load, and yield strength.

It will be noted that the treatment of a sheet by cementation allows to obtain a carbon enrichment of the entire room. The treatment of a sheet by cementation is considered impossible by those skilled in the art, particularly because of the deformations induced by heat treatments, whether it is carburizing or subsequent heat treatments. However, in the case of the membrane of the instrument according to the invention, with a spherical cap shape, the inventor has found, against prejudices, that the shape of the membrane is little affected by the heat treatments and is usable for the manufacture of the instrument.

The cementation applied to the steel makes it possible to improve the mechanical qualities, and in particular to harden it hard.

Also, increasing the carbon content in steel decreases its ductility as well as elongation. Thus, to be sufficiently stamped, the steel sheets must not contain much carbon. These steels are said to be mild steels and have carbon levels generally less than 0.1%. This amount of carbon is not sufficient for the desired characteristics of the steel.

To overcome this contradiction, the invention provides for the use of stamped mild steel sheets, which are then cemented in order to enrich them with carbon up to 0.8%. The sheets then acquired, by carburizing, a percentage of carbon sufficient to modify the mechanical properties directly. It has been found that such a sheet has a pearlitic crystalline structure with a hardness of 300 Hv.

Treatment by carburizing is much more efficient in terms of treatment exposure time and therefore much more cost-effective. Considering a sheet thickness of 1 mm, we saw that it required about 100 hours of treatment to be fully nitrided, against only 1 hour of treatment to be fully cemented.

By way of illustration, for carburizing by solid agents, the thicknesses of the carburizing, expressed in millimeters, will be a function of the temperatures and times, of:

This, whatever the thickness of the piece to be cemented.

It should be noted that, during processing, the sheet coems on both sides at the same time. For a sheet of 1 mm thickness, it is necessary to consider a cementation time corresponding to 0.5 mm.

Furthermore, the cemented sheets become able to receive, according to a first improvement, a heat treatment, quenching and tempering, which will considerably harden the sheet and thus enhance the results described above. This is possible because in order for a steel to be able to receive a so-called quenching treatment, it is necessary that the carbon content of the steel be sufficiently high at 0.2%. The heat treatment which follows the cementation is an additional constraint compared to the known nitriding process. Nevertheless, it is generally understood and integrated directly into the carburizing process chain and thus has almost no impact on time. general treatment = cementation + heat treatment, sheet metal.

Also, the heat treatment, without affecting the processing time and its cost, has demonstrated, during the tests carried out, that the different ways of modulating it in terms of types of quenching and types of income can bring advantages concerning acoustics.

If the heat treatment is, by its nature, flexible, by changing quenching and tempering parameters, this is understood in a voluntary manner, and this does not detract from the perfectly reproducible nature of this heat treatment.

According to a second improvement, the heat treatment is obtained by a normalization operation.

Regarding the acoustic aspect, the cementation makes possible a heat treatment of the plates by quenching and tempering, or else by normalization. The manner of carrying out the heat treatment, in general, makes it possible, according to the variant embodiments, to obtain fields of both sounds and sound colors that are aesthetically surprising, new and different (multiple). This is explained by the nature of the arrangement of the different crystalline structures of steel, obtained by the effects of a heat treatment (heat treatment considered made exclusively possible to date by the prior cementation of the pressed sheets), in term presence of these structures, and proportion: cementite, perlite, troostite, bainite and finally martensite.

The presence and the proportion of these components is attributable to a way of executing said heat treatment, which is controllable.

As a result, not all possible combinations have been implemented. artwork.

One can imagine to determine the one that would offer the best results. However, concerning the sound only aspect, it should be noted that the aesthetic appreciation of a sound is a very subjective aspect. There may not be, therefore, in terms of acoustics, a type of crystalline arrangement of steel that can stand out as the best, able to produce the most beautiful sound. There would be, on the contrary, a multitude of different crystalline arrangements, in different proportions, which would produce singular and distinct sounds, whether or not to touch the sensibility of each.

However, it can already be said that a sheet having in part a crystalline structure of the martensitic type, obtained by carburizing of said sheet previously stamped, then having undergone a heat treatment consisting of quenching and tempering, makes it possible to satisfy the prevention of uncomfortable disassembly and the production of acoustic quality far superior to sheet metal that has not benefited from this treatment.

The most important influence of carbon on the mechanical properties of steel is mainly due to the fact that, by quenching, very hard constituents are obtained, such as for example martensite. Other constituents, such as troostite or bainite, can be obtained by modulating the heat treatment in terms of type of quenching and type of income performed.

These constituents also allow a high frequency module.

Cementation, including carbonitriding, is carried out by solid, gaseous or liquid agents in a bath.

Carbonitriding is a cementation for which a nitrogen supply is added. The latter facilitates the penetration of carbon and allows to slightly lower the carburizing temperature; the nitrogen supplied also facilitates the heat treatment in terms of quenchability. This treatment differs from the nitriding forms in that the hardness of the steel is obtained by the effect of carbon, unlike the nitriding in which the hardness is obtained by precipitation, solid solution and chemical combination of nitrogen compounds.

The method according to the invention therefore remains well based on cementation.

Brief description of the figures

The invention will be better understood and other features and advantages will appear on reading the description which follows, the description referring to the appended drawings among which:

Figure 1 is a sectional view of a membrane for the manufacture of an instrument according to the invention;

Figure 2 is an exploded perspective view of a mounting device for the diaphragm of Figure 1;

Figure 3 is a side view of the assembly of Figure 2.

DETAILED DESCRIPTION

A membrane according to the invention for the manufacture of an idiophone instrument is shown in Figures 1 to 3. It is formed of a substantially spherical cap-shaped sheet provided at its periphery with an annular rim. The sheet is mild steel, less than 0.1% carbon. Figures 2 and 3 illustrate the method of manufacturing the membrane. The membrane is first cut in a sheet according to a disk, and then stamped to give it the shape as shown in FIG. Two hoops are fixed on either side of the annular flange by tightening it to give it a hold for the rest of the operations. The hoops are for example ceramic. Different fixing means can be used to connect the hoops together, provided they hold in temperature. This is, for example, ceramic screwing means. This assembly, as shown in Figure 3, is put in a carburizing furnace, not shown, and maintained at a temperature for a period of time for cementation. As indicated above, the temperature is of the order of 850 to 900 ° C. Although satisfactory parts could be made without this maintenance, the hoops allow to keep the shape of the membranes closer to the stamped form despite the high temperature.

Claims

1. Method for producing an idiophone percussion instrument, of the type consisting of a stamped steel membrane associated with a sound box and divided by shaping into several areas, corresponding to musical notes, vibrated by chopsticks or with the hands, characterized by the following successive steps:

- forming by stamping a steel sheet corresponding to the membrane;

carburising said sheet;

specific shaping of the resonance areas.

2. Method according to claim 1, characterized in that one carries out a heat treatment successively to the carburizing of the sheet forming the membrane.

3. Method according to claim 2, wherein the heat treatment is obtained by a quenching operation, followed by a revenue operation.

4. Method according to one of claims 1 to 3, characterized in that the carburizing, including carbonitriding, is carried out by solid gaseous agents or by liquid agents in a bath.

5. Method according to claim 2, characterized in that the heat treatment is obtained by a normalization operation.

6. Method according to one of claims 2 to 5, characterized in that the heat treatment by quenching and tempering, or by normalization, Following a cementation operation, it is able to produce different crystalline structures of the steel, in terms of presence and proportion of cementite, perlite, troostite, bainite and martensite.

7. Method according to one of the preceding claims, wherein the membrane comprises an annular rim, and said rim is sandwiched between two hoops during the carburizing operation.