JP2006047909A - Keyboard of keyboard instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a keyboard of a keyboard instrument with which the shape of a keyboard weight can be surely fixed by changing a shape of a projection (edge) of the conventional keyboard weight indentation press, thereby changing the shape so as to protrude toward the outside of the weight even with the smallest possible pressure. <P>SOLUTION: The keyboard weight composed of a simple substance metal other than harmful metals, such as lead and mercury, or a plurality of metal alloys, is fitted into a prescribed keyboard weight embedment hole and is plastically deformed by a pressurizing means from both side faces of keyboard faces by force plungers provided with a plurality of the projections having gentle inclinations on the faces heading more toward the outer side than in the central part direction and is thereby fixed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a keyboard of a keyboard instrument, and more particularly to a shape of a press die that prevents a weight used for adjusting the weight of a keyboard touch from falling out of a keyboard embedding hole even if the weight is a material other than lead.

In general, in keyboard instruments such as pianos, the weight of the key is an important factor that affects the performance of the touch, which is subtly affected by the performer. The number (1 to 3) and the embedding position are predetermined in advance.

As the keyboard material, generally coniferous wood is used. In the case of an upright piano, as shown in FIG. 1, through-holes 2-1 and 2-2 having a diameter of about 10 mm that penetrate from the pivoting fulcrum of the key 1 (the bottom of the balance pin 3) to a predetermined location on the side of the rear keyboard. The weights 2a and 2b are made of lead. (Example diagram with two weights) The grand piano is more in front of the pivot point.

As shown in FIGS. 2, 3 and 4, the conventional lead weights 2a and 2b are fitted into the through holes, and then subjected to plastic deformation from both sides of the keyboard by the pressing means (pressing die 4) shown in FIG. And fix the keyboard weight so that it does not fall off easily. Since lead is a relatively soft material, the shape of the die has a protrusion with a simple draft as shown in FIG. 4, and it was able to cause sufficient plastic deformation and not fall off. Thus, the weight of the keyboard for many years is inexpensive and the specific gravity is as large as 11.3, and lead has been used for its convenience.

この表の銅，鉄，亜鉛は比較的安価で鉛の比重には及ばないが、鉛錘の代替材料としてコスト的に要望があるが，前述のように銅、亜鉛は鉛よりも硬く鉄はさらに硬いので圧力の小さな小型のプレスでしかも従来の押型では塑性変形が困難であった。錫は若干高価で合金の一成分としての利用が考えられる。又錘の大きさについては，たとえば銅の場合、鉛錘１２φが銅錘１３．５φにしてほぼ同じ重さになる。重さのバランスは埋設位置の若干の変更などでも対応できるものである。
特開2003-177740 特開2003-162279 However, since lead is a heavy metal and harmful to the human body and the natural environment, various proposals have been made for lead removal, such as JP2003-177740 and JP2003-162279, from the viewpoint of environmental conservation. There are many proposals for the former made of iron and the latter made by mixing synthetic resin and high specific gravity metal powder such as tungsten. In the case of iron, there was a problem because the current press die was hard and did not deform. Resin mixed molded products with high specific gravity materials are expensive, and the bit (pressing die) must be heated to automatically adjust the temperature to plastically deform it. There is a problem that uniform heating deformation cannot be obtained unless the control means is added. As a result of experiments, copper and copper alloys could not be sufficiently plastically deformed, and a lead-free keyboard weight could not be realized. The following table shows the specific gravity of well-known materials that can compete with relatively inexpensive lead weights.

Although copper, iron, and zinc in this table are relatively inexpensive and do not reach the specific gravity of lead, there is a demand for cost as an alternative material for lead weight, but as mentioned above, copper and zinc are harder than lead and iron is Further, since it is hard, it is difficult to plastically deform with a small press with a small pressure and with a conventional die. Tin is slightly expensive and can be used as a component of the alloy. As for the size of the weight, for example, in the case of copper, the lead weight 12φ is set to the copper weight 13.5φ, and the weight is almost the same. The balance of weight can be dealt with even by a slight change in the buried position.
JP2003-177740 JP2003-162279

The problem to be solved is to use the current production equipment (keyboard weight press machine) to process a keyboard weight made of a relatively inexpensive single or multiple alloys such as copper, copper-iron alloy, and zinc. Therefore, it is intended to provide a press die that is embedded in the keyboard embedding hole and does not fall off.

Even if the metal or alloy is somewhat harder than lead, the shape of the pressing die is more than the direction of the center of the pressing die (the surfaces ib, ic and id in FIG. 12 and the surfaces lb and roc in FIG. 13). This is a pressing die with a gentle slope on the outer surfaces (Ia in FIG. 12 and Loa surface in FIG. 13). By pressing as shown in FIG. 5, the outer surface of the weight is plastically deformed further outward. Is possible. FIG. 6 is an enlarged plan view and an elevational view of the pressing mold of FIG. 5, and FIG. 12 shows an example of four protrusions (blades) (A), and FIG. FIGS. 8 and 9 are examples of four and eight locations, respectively, in the shape of the pressing projection (blade) (b) of FIG. In order to produce such a pressing projection (blade), after chamfering a steel bar with a lathe as shown in FIG. 10, the center is excavated as shown in FIG. Then, cutting is performed so that the required number is left, and a portion of the protrusion (blade) or its vicinity is subjected to hardening treatment such as quenching. Alternatively, there is also a method of simply brazing a carbide tip to a round bar.

According to the present invention, the keyboard weight can be fixed to the keyboard without fear of dropping by a press method similar to that of the conventional lead.

Usually, the keyboard weight has a cylindrical shape with a diameter of 12 mm to 14 mm and a length of 10 mm to 11 mm. As shown in Fig.5, in fact, it is deformed so as to produce a so-called burr on the outside by pressing and bending outward, so the tip of the pressing projection (blade) is preferably located 1mm to 2mm inside the outer circumference. The harder the material, the harder it is to deform if there is no position closer to the outside. In addition, the shape of the pressing projection is more preferably perpendicular to the pressing direction of the elevations of (b), (c), and (d) in FIG. Similarly, the low b and low c planes of FIG. 13 are preferably vertical. The number of protrusions is usually preferably 8 or more.

In the future, the industry will have to move forward in the direction of not using harmful substances, so it is expected to be used as an alternative material for various other types of caulking lead components.

It is explanatory drawing which shows the fixing method of the keyboard and keyboard weight of an upright piano. Conventional example of A-A 'cross section after inserting keyboard weight 2b into buried hole 2-2 The conventional example of the A-A 'cross section after inserting the keyboard weight 2b into the through-hole 2-2 and pressing it with a press die. Conventional example of a pressing die (blade). In order to simplify the drawing, a + mark is used, but there are a rice mark and a chrysanthemum pattern. 1 is a vertical cross-sectional view taken along the line A-A 'in FIG. 1 showing the weight 2b deformed and fixed in the keyboard insertion hole in the embodiment of the present invention. There are four examples of stamping projections (blades). There are eight examples of stamping protrusions (blades). Examples of push projections (blades) with 4 locations (b) Examples of push-shaped projections (blades) with 8 examples (b) Procedure 1 is an example of the manufacturing process of the pressing projection (blade). Procedure 2 with an example of the manufacturing process of the die projection (blade) Is a partial perspective view of the embodiment (A) of the shape of the pressing projection (blade) Is a partial perspective view of the embodiment (b) of the shape of the pressing projection (blade)

Explanation of symbols

1 keyboard
2 Keyboard weight burial holes (2-1, 2-2)
2a, 2b Keyboard weight 3 Balance pin 4 Press stamping die a a surface facing the outside of the stamping die a a surface facing the outside of the stamping die

Claims (1)

A keyboard weight made of a single metal other than harmful metals such as lead and mercury, or an alloy of a plurality of selected metals is fitted into a predetermined keyboard weight embedding hole, and the surface that faces outward from the center is gently inclined A keyboard of a keyboard instrument that can be fixed by being deformed plastically by pressing means from both sides of the keyboard with a press die provided with a plurality of protrusions

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