JP2008241839A - Hammer shank of piano and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hammer shank of a piano for suppressing dimensional changes between two arm parts due to wetting and drying so as to secure stable and smooth motions of a hammer. <P>SOLUTION: A hammer shank 24 of a piano supported by a flange 23 to rotate according to key touch is provided with: a shank main body 24a constituted with wood; bifurcated two arm parts 24b formed in one end part of the shank main body 24a, extended parallel to both sides of the flange 23 and facing each other, and freely rotatably supported by the flange 23; and a block 28 constituted with wood, in which a fiber direction is arranged along an opposing direction for suppressing displacement of the opposing direction of the two arm parts 24b facing each other, and stuck between roots of the two arm parts 24b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piano hammer shank that rotates in response to a key depression and a method for manufacturing the same.

  Conventionally, as a hammer of a piano having a hammer shank, for example, the one described in Patent Document 1 is known. The hammer is provided so as to correspond to each key, and is rotatably supported by a hammer shank flange (hereinafter simply referred to as “shank flange”). Each hammer is composed of an elongated rod-shaped wooden hammer shank and a hammer head fixed to the rear end of the hammer shank. At the front end of the hammer shank, two bifurcated left and right arm portions that are opposed to each other and extend in parallel to the front are formed. The shank frenzy is formed of a synthetic resin molded product and is screwed to the hammer shank rail. The rear end portion of the shank flange is provided with an engaging portion protruding rearward, and two arm portions of the hammer shank are engaged with both sides of the engaging portion. Further, a pin is passed horizontally through both the arm portion and the engaging portion, and this pin is fixed to the engaging portion, while being rotatable with respect to the both arm portions. Thereby, the hammer is rotatably supported by the shank flange via the pin integral with the shank flange. Further, both side surfaces of the engaging portion of the shank flange are formed in parallel to each other, and face the inner side surfaces of both arm portions of the hammer shank with a slight gap.

  With the above configuration, when the key is depressed, the action is activated, the hammer shank is pushed up, the hammer is rotated upward, and the hammer head strikes the string, thereby producing the piano sound. appear. Further, when the hammer is rotated, the hammer shank is guided by the both arm portions and the engaging portion of the shank flange, so that the hammer is rotated without being swayed from side to side.

  However, since the hammer shank is made of wood, it is easily affected by the environment in which the piano is used, particularly wet and dry, and there is a risk that smooth and stable rotation of the hammer cannot be obtained due to changes in dimensions between both arms. Specifically, when the size between the arms of the hammer shank is reduced due to shrinkage due to drying, there is no gap between the arms and the engaging portion, and the hammer does not rotate smoothly (below) May be called “stick”. Conversely, when the dimension between the arms increases due to expansion due to wetting, the gap between the arms and the engaging portion widens, and as a result, the hammer swings to the left or right when the hammer rotates. There is a possibility that stringing cannot be performed properly due to sticking.

  The present invention has been made to solve the above-described problems, and can suppress a change in dimensions between two arms due to the influence of dry and wet, thereby ensuring a smooth and stable operation of the hammer. It is an object of the present invention to provide a piano hammer shank and a method for manufacturing the same.

JP 2005-77455 A

  In order to achieve the above object, the invention according to claim 1 is a hammer shank of a piano that is supported by a frenzy and rotates in accordance with a key depression, and a shank body made of wood, and the shank body The two arm portions are formed of one piece of wood and are formed of wood and two bifurcated arm portions that are opposed to each other and extend in parallel to both sides of the frenzy and are rotatably supported by the frenzy. In order to suppress the displacement in the facing direction, the fiber direction is arranged along the facing direction, and a displacement suppressing member bonded between the roots of the two arm portions is provided.

  According to this configuration, two bifurcated arm portions that are opposed to each other and extend in parallel to both sides of the frenzy are formed at one end of the shank body that is made of wood, and both arm portions can be freely rotated in the frenzy. It is supported. Accordingly, the hammer shank rotates while being guided by the two arms and the frenzy as the key is pressed. In addition, the displacement suppressing member is disposed in the fiber direction so as to be opposed to each other in the opposing direction of the two arm portions of the shank body, and is bonded between the roots of both arm portions. Since this displacement suppression member is made of wood, it can be manufactured relatively easily and inexpensively, and since the adhesion to the arm part of the shank body is an adhesion between the woods, both have good adhesion Can be secured. As a result, the displacement suppressing member is firmly attached to both arm portions, and thereby it is possible to suppress the spread between the both arm portions particularly in a wet environment. In general, wood expands and contracts due to increase or decrease of moisture due to moisture, but in the fiber direction, the other direction, specifically, the tangential direction that touches the annual ring circle, and the radial direction that radiates from the tree center Compared with, the degree of expansion and contraction is extremely small, and expansion and contraction due to moisture is difficult to occur. Therefore, since the fiber direction of the displacement suppressing member is arranged along the opposing direction of both arms, the expansion and contraction of the displacement suppressing member due to dry and wet hardly occurs in the opposing direction of both arms.

  As described above, the displacement suppression member is bonded between the bases of the two arms of the shank body, so that both arms are restrained and the change in dimensions between the arms due to the influence of moisture is suppressed. can do. Thereby, the size of the gap between the both arms and the frenzy can be maintained, and as a result, generation of a stick due to dry and wet and shaking and rattling when the hammer rotates can be prevented. Therefore, it is possible to ensure a smooth and stable operation of the hammer regardless of whether it is dry or wet.

  The invention according to claim 2 provides a wooden hammer shank material in which two parallel forked arms facing each other are formed so as to extend continuously at one end, and the fibers extend in the width direction continuously. A preparation step for preparing a wooden displacement restraining member in which the direction is arranged, an attachment step for attaching the displacement restraining member between the roots of the two arm portions, and attaching them to the hammer shank material, and a displacement restraining member A cutting step of cutting a plurality of hammer shanks by cutting the hammer shank material to which the arm portion is attached at predetermined intervals in the extending direction of the arm portion along a direction orthogonal to the extending direction. And

  According to this configuration, first, the wooden hammer shank material and the displacement suppressing member are prepared. The hammer shank material has two forked arms that extend continuously to one end and are parallel to each other, while the displacement suppression member extends continuously and the fiber direction is arranged in the width direction. Has been. Next, the displacement suppression member is attached to the hammer shank material by inserting and bonding between the roots of both arms of the hammer shank material. And the hammer shank material is cut | disconnected along the direction orthogonal to an extending direction for every predetermined space | interval of the extending direction of an arm part, and a some hammer shank is cut out from a hammer shank material. Thereby, the hammer shank which attached the displacement suppression member between the roots of two arm parts, ie, the hammer shank which has the effect | action and effect described in the said Claim 1, can be obtained. In addition, since the hammer shank is cut after attaching the continuously extending displacement restraining member to the hammer shank material, the hammer shank can be manufactured more efficiently than when a displacement restraining member of the size corresponding to each hammer shank is attached. can do.

  Further, in general, in the manufacturing process of the hammer shank, the hammer shank material as described above, that is, the hammer shank material not attached with the displacement suppressing member is cut in the same manner as described above, so that the hammer shank material is removed from the hammer shank material. Cut out. Therefore, when manufacturing a hammer shank, processes other than the attachment process can use a conventional manufacturing line as it is, and can suppress an increase in manufacturing cost.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a keyboard 1, an action 2, a hammer 3, and the like of a grand piano to which a piano hammer shank according to an embodiment of the present invention is applied, in a key released state.

  The keyboard 1 is composed of a large number of keys 1a (only one is shown) arranged in the left-right direction of the grand piano. Each key 1a extends in the front-rear direction (left-right direction in FIG. 1), and is supported at the center so as to be rotatable about a balance pin (none of which is shown) erected on a shelf on the shelf. ing.

  The action 2 is provided above the rear part of the keyboard 1, and includes a whippen 11, a jack 12, a repetition lever 13, and the like for each key 1a. The whippen 11 extends in the front-rear direction, and is supported by the whippen frenzy 14 at the rear end. This whippen flange 14 extends in the vertical direction and is screwed to a whippen rail 16 passed to a plurality of brackets 15 (only one is shown in FIG. 1) arranged at intervals in the left-right direction. Yes. The upper end of the whippen frenzy 14 is provided with two left and right arm portions 14a and 14a (only the left one is shown in FIG. 1). The rear end portion of the wippen 11 is engaged between the both arm portions 14a and 14a, and the center pin 17 is horizontally passed through them. As a result, the whippen 11 is rotatably supported by the whippen flange 14 about the center pin 17. In addition, a heel portion 11 a that protrudes downward is provided at the center of the wippen 11 in the front-rear direction. The whippen 11 is placed on the capstan screw 1b provided at the rear part of the key 1a via the heel part 11a. A jack 12 is supported at the front end of the wippen 11.

  The jack 12 has an L-shaped side surface formed by a hammer push-up portion 12a extending in the vertical direction and a regulating button contact portion 12b extending forward at a substantially right angle from the lower end portion thereof. The front end of the wippen 11 is provided with two bifurcated left and right arms 11b and 11b (only the left one is shown in FIG. 1). A corner portion of the jack 12 is engaged between the both arm portions 11b and 11b, and a center pin 18 is passed horizontally through these. As a result, the jack 12 is rotatably supported by the front end portion of the wippen 11 around the center pin 18. Further, the upper end portion of the hammer push-up portion 12a engages with a jack guide hole 13a, which will be described later, of the repetition lever 13, and opposes a shank roller 26, which will be described later, placed on the repetition lever 13, with a slight gap therebetween. is doing. Further, the jack 12 is urged in a return direction (counterclockwise in FIG. 1) by a repetition spring 22 described later.

  The repetition lever 13 extends in the front-rear direction obliquely upward and is supported by a lever flange portion 21 that protrudes upward from the central portion of the wippen 11 in the front-rear direction. At the upper end portion of the lever flange portion 21, two left and right arm portions 21a and 21a (only the left one is shown in FIG. 1) are provided. Between these two arm portions 21a, 21a, the central portion of the repetition lever 13 is engaged, and the center pin 19 is passed horizontally through them. Thereby, the repetition lever 13 is rotatably supported by the upper end part of the lever flange part 21 centering on the center pin 19. Further, the repetition lever 13 is urged in the return direction (counterclockwise in FIG. 1) by a repetition spring 22 attached to the lever flange portion 21. Further, the repetition lever 13 is formed with a jack guide hole 13a penetrating in the vertical direction at the front portion thereof, and the hammer 3 is placed via a shank roller 26 contacting the vicinity of the jack guide hole 13a on the upper surface. Yes.

  FIG. 2 shows the hammer 3 and the hammer shank frenzy 23 (frenzy) that supports it. The hammer 3 has a hammer shank 24 extending in the front-rear direction and a hammer head 25 provided at the rear end thereof, and the hammer head 25 faces the string S (see FIG. 1) stretched upward. Yes. The hammer shank 24 is made of, for example, wood such as a side, and has an elongated rod-shaped shank body 24a. The hammer shank main body 24a is a plane in which the fiber direction is along the length direction, the width of the front end portion in the left-right direction is wider than the other portions, and the upper surface and the lower surface of the front end portion are parallel to each other. It consists of

  In addition, bifurcated left and right arms 24b and 24b are formed at the front end of the shank body 24a. As shown in FIG. 3, both arm portions 24b and 24b face each other at a predetermined interval in the left-right direction, and extend in parallel to the front. Each arm portion 24b is formed with a pin hole 24c penetrating in the left-right direction, and a cylindrical bearing 27 made of felt is attached to the pin hole 24c. A shank roller 26 is attached to the lower surface of the front end portion of the shank main body 24a, and a wooden block 28 (displacement suppressing member) is attached between the roots of the two arm portions 24b, 24b.

  The wooden block 28 is made of, for example, wood such as a side, and has the same horizontal width as the dimension between the left and right arms 24b and 24b of the shank main body 24a and the same height as the height of the front end of the shank main body 24a. And a block having a predetermined thickness (for example, 3 to 10 mm). Further, the wooden block 28 is configured such that the fiber direction is along the width direction. That is, in the wooden block 28 attached between the bases of the both arm portions 24b and 24b, the fiber direction is arranged along the direction in which the both arm portions 24b and 24b face each other (hereinafter referred to as “opposing direction” as appropriate). Has been.

  A hammer shank flange (hereinafter referred to as “shank flange”) 23 is made of, for example, a synthetic resin, and is screwed to the upper surface of a hammer shank rail 29 (see FIG. 1) passed between a plurality of brackets 15. ing. As shown in FIG. 3, the shank flange 23 extends in the front-rear direction and has a rectangular cross section. At the rear end of the shank flange 23, there is an engagement portion 23a that has a width slightly smaller than the dimension between both arms 24b, 24b of the hammer shank 24 and projects rearward to engage between both arms 24b, 24b. Is provided. The engaging portion 23a is formed with a pin attachment hole 23b penetrating in the left-right direction. Then, in a state where the engaging portion 23a is disposed between the both arm portions 24b and 24b with a slight gap between them, the center pin 20 is connected to the bearings 27 and 27 and the pin between them. It is passed through the mounting hole 23b. A center portion of the center pin 20 is fixed to the pin mounting hole 23b, and both end portions are rotatable with respect to the bearings 27 and 27. Thereby, the hammer 3 is rotatably supported by the shank flange 23 via the center pin 20 integrated with the shank flange 23.

  According to the above configuration, when the key 1a is pressed from the key release state shown in FIG. 1, the whippen 11 is pushed up via the capstan screw 1b and thereby pivots upward about the center pin 17 At the same time, the jack 12 and the repetition lever 13 also rotate about the center pins 18 and 19 respectively. The hammer 3 is pushed up by the jack 12 through the shank roller 26 and guided by the arms 24b and 24b of the hammer shank 24 and the engaging portion 23a of the shank flange 23, with the center pin 20 as the center. By turning clockwise 1 the string S is struck, thereby producing a piano sound.

  Next, the wet and dry test conducted on the hammer shank will be described. FIG. 4 shows a front end portion of a hammer shank subjected to a wet and dry test. (A) and (b) are the hammer shanks 24 of Examples 1 and 2, respectively. A wooden block 28 is attached between the roots of the arm portions 24b, 24b. On the other hand, (c) is a hammer shank 30 that is generally used conventionally, and unlike the first and second embodiments, the wooden block 28 is not attached to the shank body 30a. In addition, the shank main bodies 24a and 30a of the hammer shanks 24 and 30 are each configured by a side, and the fiber direction thereof is arranged along the length direction (vertical direction in FIG. 4). Furthermore, the wooden block 28 attached to the shank main body 24a of the first and second embodiments is configured with a side, and is arranged so that the fiber direction is along the opposing direction (the left-right direction in FIG. 4) of both arm portions 24b and 24b. The former thickness t is set to 3 mm, and the latter thickness t is set to 7 mm. In addition, these wooden blocks 28 are bonded between the bases of both arm portions 24b and 24b with an adhesive for wood (for example, vinyl acetate adhesive). In addition, the shank main body 24a of Examples 1 and 2 is manufactured by appropriately cutting the same one as the shank main body 30a of the conventional example between the roots of both arm portions 30b and 30b. Moreover, in the hammer shank 24 of Examples 1 and 2, the length from the tip of the arm portion 24b to the wooden block 28 is set to be substantially the same.

  The hammer shanks 24, 24 of Examples 1 and 2 having the above-described configuration and the conventional hammer shank 30 are manufactured in a normal state (for example, a temperature of 20 ° C. and a humidity of 50%). First, the hammer shanks 24, 24 and 30 was left in a test chamber under predetermined humidification conditions (temperature 23 ° C., humidity 95%) for one week. Thereafter, the dimensions between both arm portions 24b, 24b of the hammer shank 24 and between both arm portions 30b, 30b of the hammer shank 30 (hereinafter referred to as “inter-arm portion dimension W”) were measured. Next, the hammer shanks 24, 24 and 30 after humidification were left in a test chamber under predetermined drying conditions (temperature 48 ° C., humidity 30%) for 3 days. Thereafter, the inter-arm dimension W of the hammer shanks 24 and 30 was measured in the same manner as after humidification. In this dry and wet test, 20 hammer shanks 24 and 24 of Examples 1 and 2 and 20 conventional hammer shanks 30 were produced, and the inter-arm dimension W was measured. FIG. 5 shows the test results of the wet and dry test, and shows the average rate of change of the inter-arm portion dimension W, which is 100% of the conventional example. In addition, after humidification of the hammer shanks 24, 30, the distance between the arms changes so that the distance W between the arms increases, and conversely, after drying, the distance between the arms decreases and the distance between the arms increases. It changed so that W became small.

  As shown in FIG. 5, the rate of change after humidification is 100% in the conventional example, whereas 27.0% in the first example and 32.4% in the second example. From this result, by attaching the wooden block 28 between the bases of both arm portions 24b, 24b, the wooden block 28 is not attached to the spread between the both arm portions 24b, 24b of the hammer shank 24 in a wet environment. Compared with the conventional hammer shank 30, it can be seen that it can be suppressed to around 30%. Moreover, about the change rate after drying, Example 1 is 17.5% and Example 2 is 5.0%. From this result, it can be seen that, in a dry environment, the narrowing between the arms 24b, 24b of the hammer shank 24 can be suppressed to less than 20% compared to the conventional hammer shank 30. In particular, in the second embodiment in which the thickness t of the wooden block 28 is larger than that of the first embodiment, the rate of change is as extremely small as 5.0%. It turns out that the narrowing between 24b and 24b can be suppressed more effectively. Although data is omitted, it was confirmed that both the wooden blocks 28 of Examples 1 and 2 were firmly adhered to the inner side surfaces of both arm portions 24b and 24.

  As described above, in the present embodiment, the wooden block 28 is attached by bonding between the roots of the two arm portions 24b and 24b of the shank body 24a. Since the wooden block 28 is made of wood, it can be manufactured relatively easily and inexpensively. Moreover, since the adhesion of the shank body 24a to the arm portion 24b is an adhesion between the woods, both of them are good. Adhesiveness can be ensured. As a result, the wooden block 28 is firmly attached to the inner side surfaces of the both arm portions 24b, 24b, thereby suppressing the spread between the both arm portions 24b, 24b particularly in a wet environment. Further, since the fiber direction of the wooden block 28 is arranged along the opposing direction of the both arm portions 24b, 24b, the expansion and contraction of the wooden block 28 due to dry and wet occurs almost in the opposing direction of the both arm portions 24b, 24b. Absent. Therefore, when the wooden block 28 is bonded between the bases of the arms 24b and 24b of the shank body 24a, the arms 24b and 24b are constrained, and the dimensions between the arms 24b and 24b due to the influence of dry and wet conditions. Can be suppressed. Thereby, the size of the gap between the inner side surfaces of both arms 24b and 24b and the engaging portion 23a of the shank flange 23 can be maintained. As a result, generation of a stick due to dry and wet and rotation of the hammer 3 rotate. It is possible to prevent left and right shaking and rattling when doing. Therefore, the smooth and stable operation of the hammer 3 can be ensured regardless of whether it is dry or wet.

  Next, a method for manufacturing the hammer shank 24 will be described. FIG. 6 shows a part of the steps of the method for manufacturing the hammer shank 24 in order. As shown in FIG. 2A, first, a wooden hammer shank material 31 and a wooden block material 32 (displacement suppressing member) are prepared (preparation step). Specifically, a hammer shank material formed by cutting a plate material having a predetermined shape and size so that two parallel bifurcated arm portions 31a, 31a that are opposed to each other extend continuously at one end portion. Prepare 31. At the same time, a wooden block member 32 having a cross-sectional shape complementary to the roots of both arms 31a and 31a of the hammer shank member 31 and extending continuously is prepared. In this wooden block member 32, the fiber direction is arranged in the width direction. Therefore, when the wooden block member 32 is attached between the two arm portions 31 a and 31 a of the hammer shank member 31, the fiber direction is set to both arms. The portions 31a and 31a coincide with each other in the opposing direction.

  Next, after applying the same adhesive as described above to the roots of the inner side surfaces of both arm portions 31a, 31a of the hammer shank material 31, the wooden block member 32 is inserted between the roots of both arm portions 31a, 31a. Adhere (attachment process). Thereby, as shown in FIG.6 (b), the wooden block material 32 is firmly attached between the bases of both the arm parts 31a of the hammer shank material 31, and 31a. Next, as shown in FIG. 3C, the hammer shank member 31 with the wooden block member 32 attached thereto is ground at a predetermined interval T in the extending direction of the arm portion 31a along a direction orthogonal to the extending direction. Cut by splitting (cutting process). Thereby, a plurality of hammer shanks (hereinafter referred to as “half-finished hammer shanks”) substantially the same as the hammer shanks 24 to which the wooden blocks 28 are attached are cut out. Thereafter, the half-finished hammer shank is appropriately cut to obtain the above-described hammer shank 24, that is, the hammer shank 24 having the wooden block 28.

  According to this hammer shank manufacturing method, the wooden block member 32 that extends continuously is attached to the hammer shank member 31, and then the hammer shank member 31 is cut. Therefore, when the wooden block 28 is attached to each shank body 24a. In comparison, the hammer shank 24 having the wooden block 28 can be efficiently manufactured. Further, as described above, since the steps other than attaching the wooden block member 32 to the hammer shank material 31 are the same as the conventional hammer shank manufacturing steps, when manufacturing the hammer shank 24, the conventional manufacturing is performed. The line can be used as it is, and an increase in manufacturing cost can be suppressed.

  In the embodiment, a side is illustrated as the type of wood employed in the wooden block 28, but the wooden block 28 of the present invention is not limited thereto, and both arms 24b of the shank body 24a by dry and wet, Other types of wood can be used as long as the displacement between 24b can be suppressed. Further, the detailed configuration of the shank body 24a of the hammer shank 24 and the wooden block 28 shown in the embodiment are merely examples, and can be appropriately changed within the scope of the gist of the present invention.

It is a side view which shows the keyboard, action, hammer, etc. of the grand piano using the hammer shank by embodiment of this invention in a key release state. It is a perspective view which shows a hammer and a hammer shank frenzy. It is a disassembled perspective view which expands and shows the connection part of the hammer shank and hammer shank flange of FIG. It is a top view which shows the front-end part of the hammer shank which performed the wet and dry test, (a) Example 1, (b) Example 2, and (c) a prior art example are shown. It is a table | surface which shows the test result of a wet / dry test. It is explanatory drawing for demonstrating the manufacturing method of a hammer shank.

Explanation of symbols

1 Keyboard 1a Key 3 Hammer 23 Hammer Shank Frenzy (Frenzy)
24 hammer shank 24a shank main body 24b arm part 28 wooden block (displacement suppressing member)
31 Hammer Shank Material 31a Arm 32 Wooden Block Material (Displacement Suppression Member)

Claims (2)

A hammer shank of a piano that is supported by frenzy and rotates with the key press,
A shank body made of wood,
Two bifurcated arms formed on one end of the shank body, facing each other and extending in parallel on both sides of the flange, and rotatably supported by the flange.
Displacement that is made of wood and in which the fiber direction is arranged along the facing direction and is bonded between the roots of the two arm portions in order to suppress displacement of the two arm portions facing each other. A restraining member;
A piano hammer shank characterized by comprising Prepare a wooden hammer shank material formed so that two parallel forked arms facing each other extend continuously to one end,
A preparation step of preparing a wooden displacement suppressing member that continuously extends and the fiber direction is arranged in the width direction;
An attachment step of attaching the displacement suppressing member to the hammer shank material by inserting and bonding between the roots of the two arm portions;
A cutting step of cutting a plurality of hammer shanks by cutting the hammer shank material to which the displacement suppressing member is attached at predetermined intervals in the extending direction of the arm portion along a direction orthogonal to the extending direction;
A method of manufacturing a hammer shank for a piano, comprising:

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