JP5555417B2 - Wood member for musical instrument and method for manufacturing the same - Google Patents

Description

  The present invention relates to a wooden member for musical instruments such as keys, scissors, hammer shanks and the like used for pianos and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, as a wooden member for musical instruments (hereinafter simply referred to as “wood member”) and a manufacturing method thereof, for example, those described in Patent Document 1 are known. In this manufacturing method, a wood material (hereinafter simply referred to as “wood material”), which is a raw material of a wood member after being processed or molded, is used as high-pressure steam at a temperature of 120 to 200 ° C. and a pressure of 0.2 to 1.6 MPa. The wood member is manufactured by leaving it in an autoclave filled with 1 to 60 minutes. By such high-pressure steam treatment, the wood material is modified, and a deep color tone is imparted to the wood member. As a result, a unique texture and depth not found in a wood member not subjected to high-pressure steam treatment are obtained, and the painting process is shortened.

  However, in general, a wood material is easily damaged by cracks and the like because fine scratches existing near the outer surface grow due to tensile stress. On the other hand, since the above-mentioned conventional wooden member is only modified by the high-temperature steam treatment, the wooden member cannot be prevented from being damaged due to the above cause. As a result, the generated damage may adversely affect the operation and appearance of the instrument.

  The present invention has been made to solve such a problem, and by preventing damage such as cracking of a wooden member, it ensures a smooth and stable operation of the musical instrument and provides a good appearance of the musical instrument. An object of the present invention is to provide a wooden member for musical instruments that can be maintained over a long period of time and a method for producing the same.

Japanese Patent No. 3562517

In order to achieve this object, the invention according to claim 1 is a wood member for musical instruments, wherein the wood member is heated in advance until the wood member is completely dry with a moisture content of 0%. By performing the treatment, the cooling treatment, and the humidity conditioning treatment, at least the compression internal stress remains in the vicinity of the outer surface.

  This wooden member for musical instruments is preliminarily heat-treated, cooled and conditioned. By this heat treatment, the crystallinity of cellulose constituting the wood member increases, so that the Young's modulus increases, the equilibrium moisture content decreases, and the hygroscopicity decreases. As a result, the degree of expansion / contraction of the wooden member with respect to the wet and dry conditions (hereinafter referred to as “expansion / shrinkage ratio”) is reduced, and as a result, the dimensional stability of the wooden member due to the wet and dry conditions can be improved.

In addition, the wood member is preliminarily dried to a moisture content of 0% by heat treatment, and after the wood material is cooled, the moisture content is adjusted to a moisture content according to the usage environment. Yes. With this humidity conditioning treatment, moisture enters from the surface of the wooden member, but does not become uniform up to the inside. Therefore, a moisture gradient is generated inside the wooden member, and the expansion rate varies depending on the moisture gradient. Therefore, an internal stress of compression remains at least near the outer surface of the wooden member. Such compression internal stress prevents fine scratches existing near the outer surface of the wooden member from growing due to tensile stress, and makes the wooden member difficult to break. As a result, it is possible to ensure a smooth and stable operation of the musical instrument and to maintain a good appearance of the musical instrument over a long period of time as compared with a conventional wooden member. As a result, the maintenance cost of the musical instrument can be reduced.

In order to achieve the above object, the invention according to claim 2 is a method for producing a wooden member for musical instruments, wherein the wooden member used as the material of the wooden member is completely dried with a moisture content of 0%. A heating step of heating at a predetermined temperature, a cooling step of cooling the heated wooden material, and an internal stress of compressing the cooled wooden material at least near the outer surface of the wooden material until a state is reached. And a humidity control step for adjusting the humidity.

According to this manufacturing method, first, the wood material that is the material of the wood member is heated until it is in a completely dry state with a moisture content of 0% . Thereby, as above-mentioned, the expansion-contraction rate by the wet and dry of a wooden member reduces, and a dimensional change is suppressed. As a result, the yield at the time of manufacturing the wooden member is improved, and the manufacturing cost can be reduced.

  Moreover, the wood material in a completely dry state is cooled by heat treatment. Thereafter, the wood material in a completely dry state is conditioned so as to have a moisture content according to the use environment. At this time, moisture enters from the surface of the wooden material, but does not become uniform up to the inside. Therefore, a moisture gradient is generated inside the wooden material, and the expansion coefficient varies depending on the moisture gradient. Therefore, an internal stress of compression is generated at least near the outer surface of the wooden material. Due to the internal stress of the compression, the fine scratches existing near the outer surface of the wood material are prevented from growing due to the tensile stress, and the wood material is hardly broken. As a result, as compared with the wood material manufactured by the conventional manufacturing method, the influence of damage is eliminated, so that a smooth and stable operation of the musical instrument can be ensured and a good appearance of the musical instrument can be maintained.

  The invention according to claim 3 is the method for producing a wooden member for musical instrument according to claim 2, wherein the humidity adjusting step is a drying step of drying the cooled wooden material so that its moisture content is in an equilibrium state. It is characterized by including.

  According to this manufacturing method, by drying the cooled wood material, the wood material absorbs moisture in the atmosphere, and the moisture content is in an equilibrium state. Thereby, since it becomes difficult to perform moisture absorption / release in the wood material, it is possible to further suppress the dimensional change and deformation due to the wet and dry of the wood member.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a key 1 of a grand piano according to an embodiment of the present invention. The key 1 is composed of a plurality of white keys 1a and a plurality of black keys 1b (only one is shown in FIG. 1). As shown in FIG. 2A, each white key 1a includes a key body 2a as a wooden member, a white key cover 3a attached to the front portion of the upper surface of the key body 2a, and the like. As shown in FIG. 2B, each black key 1b includes a key body 2b, a black key cover 3b attached to the front portion of the upper surface of the key body 2b, and the like.

  The key body 2a of the white key 1a and the key body 2b of the black key 1b (hereinafter collectively referred to as “key body 2”) are made of a solid plate material made of spruce or the like and have a rectangular cross section. And extends in the front-rear direction. A center seat plate 4 having a balance pin hole 4a formed at the center in the front-rear direction of the upper surface of the key body 2, and a capstan seat plate 5 to which a capstan screw (not shown) is attached on the rear side, A back check seat plate 6 to which a back check (not shown) is attached is bonded to the rear end portion.

  The white key cover 3a is made of cellulose acetate resin or the like and has an L-shaped side surface shape (see FIG. 2A).

  The black key cover 3b is made of a synthetic resin such as a phenol resin, and is formed in a hollow shape that extends in the front-rear direction and opens downward (see FIG. 2B).

  Next, a method for manufacturing the key 1 having the above-described configuration will be described in detail. FIG. 3 shows the overall flow of the manufacturing process.

  In the first step 1 (illustrated as “S1”, the same applies hereinafter), a plurality of wood materials 11 which are materials of the key body 2 are preliminarily conditioned (preliminary humidity adjusting step). As shown in FIG. 4, each wooden material 11 has a long shape with a standard length L = 500 mm, a width W = 50 to 150 mm, and a thickness T = 25 mm, for example.

  Preliminary humidity control of the wood material 11 is performed by cutting a raw wood such as spruce into a plate shape, and then putting it in a preliminary humidity control chamber (not shown), with a predetermined temperature (for example, 50-100 ° C.) and humidity (for example, 30-30). 90%) forcibly drying. As a result, the wood material 11 is adjusted to a predetermined moisture content (for example, 8%).

  Next, in step 2, the plurality of wood materials 11 subjected to the preconditioning process in step 1 are heated by the heating device 21 shown in FIGS. 5 and 6 (heating process).

  The heating device 21 includes a flat box-shaped heating chamber 22, a mesh belt 23 provided horizontally in the heating chamber 22 on which the wooden material 11 is placed, a plurality of first heaters 24 a that heat the wooden material 11, and A plurality of second heaters 24b, a first temperature sensor 25a and a second temperature sensor 25b for detecting a surface temperature T1 and a back surface temperature T2 of the wood material, respectively, and a control device 26 for controlling the first and second heaters 24a and 24b. It has.

  The plurality of first and second heaters 24a and 24b are arranged at equal intervals above and below the mesh belt 23 so as to be spaced apart from each other and aligned along the length direction thereof. The 1st and 2nd heaters 24a and 24b are comprised by the far-infrared heater which act | operates by ON / OFF, for example.

  The first and second temperature sensors 25a and 25b are directly attached to the center of the front and back surfaces of each wooden material 11. Each of the first and second temperature sensors 25 a and 25 b is constituted by, for example, a thermocouple, detects the surface temperature T 1 and the back surface temperature T 2 of the wood material 11, and outputs detection signals to the control device 26.

  The control device 26 is configured by a microcomputer including a CPU, ROM, RAM, and input / output circuit. As shown in FIG. 6, the control device 26 will describe the first and second heaters 24 a and 24 b later according to the surface temperature T1 and the back surface temperature T2 output from the first and second temperature sensors 25 a and 25 b. To control.

  In this heating step, a plurality of wood materials 11 (only one is shown in FIG. 5) are meshed so that the length direction thereof matches the arrangement direction of the plurality of first and second heaters 24a and 24b. After the heating chamber 22 is closed, the first and second heaters 24a and 24b are heated for a predetermined time. This predetermined time is, for example, 30 minutes to 30 hours, and is set to 25 hours in the present embodiment.

  FIG. 7 is a flowchart showing a heating control process executed by the control device 26 in order to control heating by the first and second heats 24a and 24b. This process is repeatedly executed every predetermined time (for example, 0.1 second). In this process, first, the first heater 24a is controlled in steps 11-14.

  In step 11, the surface temperature T1 detected by the first sensor 25a is a temperature obtained by subtracting a predetermined value ΔT (for example, 2 °) corresponding to hysteresis from the first predetermined temperature TREF1 (for example, 105 to 200 ° C.). It is determined whether it is lower than ΔT). When the determination result is YES, after the first heater 24a is operated (ON) (step 12), the process proceeds to step 15 described later.

  On the other hand, when the determination result in step 11 is NO, in step 13, it is determined whether or not the surface temperature T1 is higher than a temperature obtained by adding a predetermined value ΔT to the first predetermined temperature TREF1 (TREF1 + ΔT). When the determination result is YES, the first heater 24a is stopped (OFF) (step 14), and then the process proceeds to step 15.

  When the determination result of step 13 is NO, the process directly proceeds to step 15.

  By controlling the first heater 24a as described above, the surface temperature T1 detected by the first temperature sensor 25a is controlled to be the first predetermined temperature TREF1.

  Further, when the surface temperature T1 is in the range of (TREF1−ΔT) ≦ T1 ≦ (TREF1 + ΔT) (step 13: NO), the first heater 5a is maintained in the ON / OFF state immediately before the first heater 5a. The frequent switching of ON / OFF of 24a is prevented.

  Next, in steps 15-18, the second heater 5b is controlled.

  In step 15, it is determined whether the back surface temperature T2 detected by the second sensor 25b is lower than a temperature (TREF2-ΔT) obtained by subtracting a predetermined value ΔT from a second predetermined temperature TREF2 (for example, 105 to 200 ° C.). Determine. When the determination result is YES, the second heater 24b is operated (step 16), and then this process is terminated.

  On the other hand, when the determination result in step 15 is NO, it is determined in step 17 whether or not the back surface temperature T2 is higher than a temperature (TREF2 + ΔT) obtained by adding a predetermined value ΔT to the second predetermined temperature TREF2. When the determination result is YES, the second heater 24b is stopped (step 18), and then this process is terminated.

  When the determination result of step 17 is NO, this process is ended as it is.

  By controlling the second heater 24b as described above, the back surface temperature T2 detected by the second temperature sensor 25b is controlled to be the second predetermined temperature TREF2.

  When the back surface temperature T2 is in the range of (TREF2−ΔT) ≦ T2 ≦ (TREF2 + ΔT) (step 17: NO), the ON / OFF state immediately before the second heater 24b is maintained, whereby the second heater The frequent switching of ON / OFF of 24b is prevented.

  Returning to FIG. 3, in step 3, a plurality of heat-treated wood materials 11 are put into a cooling chamber (not shown) and rapidly cooled under conditions of a predetermined temperature (for example, 20 ° C.) and humidity (for example, 50%). (Cooling process). The plurality of woody materials 11 are in a so-called completely dry state in which the moisture content is 0% by the heat treatment described above.

  Next, in step 4, the cooled wood material 11 is placed in a drying chamber (not shown) and dried under conditions of a predetermined temperature (for example, 20 ° C.) and humidity (for example, 60%) (drying process). By such a drying process, the wood material 11 absorbs moisture in the drying chamber, and the moisture content becomes an equilibrium state. However, although moisture enters from the surface of the wooden material 11, it does not become uniform up to the inside. Accordingly, a moisture gradient is generated inside the wooden material 11 and the vicinity of the outer surface of each wooden material 11 expands due to moisture absorption, while the other inner portions are substantially maintained in a completely dry state, so that the shrinkage is still maintained. try to. As a result, due to the difference in expansion, expansion near the outer surface is constrained by the inner portion, so that compressive internal stress remains in the vicinity of the outer surface, and tensile internal stress remains in the inner portion.

  Next, in step 5, a plurality of wood materials 11 that have been dried are assembled (assembly process). Specifically, after a plurality of wooden materials 11 are joined together by width separation (see FIG. 8), the white key cover 3a and the black key cover 3b are bonded to predetermined positions on the front portion of the key body 2a for one piano. At the same time, a belt-like middle seat plate 4A, a capstan seat plate 5A, and a back check seat plate 6A for one piano are bonded to a predetermined position on the rear side (see FIG. 9). The white key cover 3a is formed of a molding unit for one octave.

  Finally, in step 6, the plurality of wood members 11 assembled as described above are cut into strips as shown in FIG. 10 using a grinder (not shown) (cutting step). Thereby, the key 1 shown in FIG. 1 is completed.

  As described above, according to the present embodiment, since the wooden member 11 that is the material of the key 1 is heat-treated as described above, the crystallinity of cellulose constituting the wooden material 11 is increased. The expansion / contraction rate due to the wet and dry of the wooden material 11 can be reduced, and the dimensional change and deformation due to the wet and dry of the key body 2 can be suppressed. As a result, the touch feeling of the key 1 can be stably maintained, and noise caused by touching other adjacent keys can be prevented.

  Moreover, since the dimensional change of the key main body 2 is suppressed, the yield at the time of manufacturing the key 1 can be improved, and the manufacturing cost can be reduced.

  Further, when the wood material 11 is heat-treated, the first and second heaters 24a and 24b are set so that the detected surface temperature T1 and back surface temperature T2 become the first predetermined temperature TREF1 and the second predetermined temperature TREF2, respectively. Control independently of each other. Thereby, the surface temperature T1 and the back surface temperature T2 of the wood material 11 can be finely controlled, and therefore the wood material 11 having desired physical properties modified by the heat treatment can be manufactured with high accuracy.

  Further, since the heat-treated wood material 11 is cooled and conditioned, the fine scratches present near the outer surface of the wood material 11 are pulled by the compressive internal stress remaining near the outer surface of the wood material 11. Growth due to stress is prevented, and the key body 2 is less likely to break. As a result, as compared with the conventional key, it is possible to ensure a smooth and stable operation, maintain a good appearance over a long period of time, and reduce maintenance costs.

   In addition, the sound board 11 is dried after the cooling process, so that the moisture content is in an equilibrium state. Thereby, moisture absorption / release in the wood material 11 is difficult to be performed, so that dimensional change and deformation due to dry / wet of the key body 2 can be further suppressed.

  In addition, this invention can be implemented in various aspects, without being limited to the embodiment described above. For example, in the embodiment, by the rapid cooling / humidifying treatment after the heat treatment, the compression internal stress remains in the vicinity of the outer surface of the wooden material 11 and the tensile internal stress remains in the inner portion. However, compression internal stress may remain in the entire wood material 11.

  In the embodiment, the wooden member for a musical instrument is an example of a key of a grand piano. However, the present invention is not limited to this, and the wooden member for any musical instrument, for example, a grand piano and an upright piano is used. It is possible to apply it to cocoons and hammer shanks. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

It is a perspective view which shows the key of the grand piano to which this invention is applied. (A) The longitudinal cross-sectional view of a white key, (b) The longitudinal cross-sectional view of a black key. It is a figure which shows the flow of the manufacturing process of a key. It is a perspective view of a wooden material. It is a figure which shows a heating apparatus typically. It is a figure which shows the structure of the control relationship of a heating apparatus. It is a flowchart which shows the heating control process performed with the control apparatus of FIG. It is a perspective view of the state where a plurality of wood materials were joined by width-separation. It is a perspective view of a state where a white key cover or the like is bonded to a plurality of wood materials that have been width-bonded. It is a perspective view of a state where a plurality of wood materials to which a white key cover or the like is bonded are ground.

Explanation of symbols

1 Key 2 Key body (wooden material)
2a Key body of white key (wooden member)
2b Black key body (wooden member)

Claims (3)

A wooden member for musical instruments,
The wood member is preliminarily subjected to heat treatment, cooling treatment, and humidity control treatment for heating the wood member until the moisture content becomes 0%, so that an internal stress of compression is at least near the outer surface. A wooden member for musical instruments, characterized in that it remains. A method for manufacturing a wooden member for musical instruments,
A heating step of heating the wood material, which is a material of the wood member, at a predetermined temperature until the moisture content is 0% in a completely dry state ;
A cooling step for cooling the heated wood material;
A humidity conditioning step for conditioning the cooled wood material so that compression internal stress is generated at least near the outer surface of the wood material;
A method for producing a wooden member for musical instruments, comprising:   The method for producing a wooden member for a musical instrument according to claim 2, wherein the humidity adjusting step includes a drying step of drying the cooled wood material so that the moisture content thereof is in an equilibrium state. .

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