JPH0934444A - Frame unit of acoustic piano and its fitting construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen the degree of freebom for selection of assembling process and attain weight reduction and cost reduction by providing hitch pins with which chords can be stretched between tuning pins and themselves, on the surface of a frame. SOLUTION: A frame unit is formed so that a pin board 3 projectingly provided with tuning pins 21 can be fitted to the back, and when the pin board 3 is fitted to the frame unit, it is provided with a frame 1 having an opening part to which the tuning pins 21 face, and hitch pins 22 provided on the surface of the frame 1 and with which chords can be stretched between the tuning pins 21 and themselves. When the pin board 3 projectingly provided with the tuning pins 21 is fitted to the frame unit FU, the tuning pins face from the opening part of the frame 1, hence a flat plate part having tuning pin holes for penetrating the tuning pins 21 becomes dispensable, and curtailment of material cost and weight reduction for the frame can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame unit for an acoustic piano and its mounting structure.

[0002]

2. Description of the Related Art FIG. 9 is an assembly process drawing of a conventional acoustic piano. In the drawing, "GP only" shows a grand piano only process, and "UP only" shows an upright piano only process. Assembling in the case of an upright piano has been generally performed by the following procedure (see FIG. 10 (a)). Even in the case of a grand piano, basically the same procedure is used for assembly. First, the column assembly 104 is assembled from the base 2, the column 4, the column 40, the box 41, and the column attachment 42. After mounting a batting 9 having an inclination on the front side to give a sound to the soundboard 12, the strut assembly 104 is attached.
The sound board 12 to which the sound stick 13 and the piece 16 are adhered, and the pin board 103
And attach. Next, the tuning pin hole 1 is formed on the flat plate portion 126 on the upper side.
21 is formed and a hitch pin 22 is provided on the lower surface of the frame 101 (see FIG. 11).
The string S is attached to the pillar assembly 104 in a state of being adhered to the front surface of the, and the tuning pin 21 is embedded in the pin plate 103 through the tuning pin hole 121 of the frame 101, and then the string S is stretched between the hitch pin 22. Next, attach the main board and shelf board, place the keyboard and attach actions, perform tuning and tuning, install the roof, attach case materials such as upper front board and lower front board, and perform sound adjustment finishing and inspection. After that, the assembly is completed (see FIG. 10A).

In this case, in the step of burying the tuning pin 21 in the above, as shown in FIG.
Pin plate 1 in the tuning pin hole 121 of the frame 101
03, a pin bush 124 made of the same material as that of 03 is punched, a hole for the tuning pin 21 is made in the pin plate 103 by using this pin bush 124 as a guide, and then the tuning pin 21 is punched in the hole, so that the tuning pin 21 is a frame. It penetrates 101 and is embedded in the pin plate 103.

[0004]

However, in such a conventional assembling method, the strut assembly 104 is used as a base.
The individual components, namely the sound board 12, the pin board 103,
Since the frame 101, the string S, the parent board, the shelf board, the keyboard, the action, etc. must be mounted in sequence, normally,
All of these assemblies are done in the same place. as a result,
Since a vast space for storing and assembling parts and large-scale production equipment are required, the degree of freedom in choosing the assembly location is narrowed, and the lack of mobility in production makes it suitable for small-to-medium-volume production and overseas production. However, there is a drawback that it cannot be easily handled. Further, since most of all the steps are performed after the end of the previous step, there is a drawback that the period required for all the steps from the start of the pillar assembly to the inspection becomes long.

By the way, in the case of the above-mentioned assembly method, since the frame 101, from frame casting to frame painting, is carried out independently of the other steps, the preceding production by demand forecasting, expansion of the scale of production equipment, or production Decentralization of bases,
For example, the delivery time can be shortened by outsourcing production overseas. However, after the completion of the frame alone, it is gathered together with the other parts in the same assembly place as described above, and the completion of the steps from the pillar assembly to the attachment of the pin plate 103 (in the assembly step) is waited for. I can't proceed with the process. Therefore, even if the frame alone is completed first, the time required for all the processes cannot be shortened, and some of the processes cannot be performed at a place different from the final assembly place. That is, the problem of not being able to obtain the freedom of choice of place and the maneuverability of production cannot be solved.

There is a step of embedding the tuning pin 21 before the stringing step after the frame 101 is attached. As described above, one tuning pin 2 is used.
Even if only 1 is buried, complicated work such as driving the pin bush, drilling the tuning pin into the pin plate and driving the tuning pin is required, and the number of the tuning pins 21 is enormous. However, this burying process takes time, and this burying process is one of the causes for prolonging the period required for all the processes.

The present invention has been made to solve such a problem, and the tuning pin burying process can be independently carried out without waiting for the completion of other processes such as supporting column assembly. It is an object of the present invention to provide a frame unit of an acoustic piano and a mounting structure thereof, which can widen the degree of freedom in selection of an assembly procedure and can reduce weight and cost.

[0008]

In order to achieve the above object, in the frame unit of an acoustic piano according to claim 1 of the present invention, a pin plate on which a tuning pin is projected is formed so that it can be attached to the back surface, A frame having an opening through which the tuning pin faces when the pin plate is attached, and a hitch pin that is provided on the surface of the frame and is capable of stringing between the tuning pin and the tuning pin. And

In this acoustic piano frame unit, when the tuning pin is exposed from the opening of the frame when the pin plate with the tuning pin projecting is attached, the tuning pin is penetrated into the frame. Since the flat plate portion having the pin hole is not necessary, the material cost and the weight of the frame can be reduced. Further, as a result, since the tuning pin can be directly embedded in the pin plate, the above-mentioned processing work required for embedding the tuning pin, that is, driving the pin bush into the tuning pin hole of the frame, Using this pin bush as a guide, a tuning pin hole is opened in the pin plate, the tuning pin is driven into that hole, and the work of penetrating the frame and embedding it in the pin plate is unnecessary, resulting in a reduction in the processing cost. In addition, the period required for the frame processing step can be shortened.

The acoustic piano frame unit according to a second aspect of the present invention is the acoustic piano frame unit according to the first aspect, further comprising a pin plate attached to the back surface of the frame and in which tuning pins are embedded and fixed. It is characterized by having.

In this acoustic piano frame unit, a pin plate provided with a tuning pin is attached to the back surface of the frame as a part of the frame unit in advance, so that a part of the front step of the frame attachment, that is, the pin plate attachment is performed. Can be performed independently of the other steps at the frame assembling place, so that the steps at the final assembling place can be reduced. In addition, since the frame unit having this configuration has both the tuning pin and the hitch pin, the string can be stretched between the tuning pin and the hitch pin, which is conventionally a post process of frame mounting. Part of the stringing process can be performed in advance.

Furthermore, the mounting structure of the frame unit of the acoustic piano of claim 3 is based on a base, a pillar vertically fixed to the base, a strut mounted on the front surface of the strut, and a front surface of the strut. The frame unit according to claim 1 or 2 is fixed to a front surface side of a supporting column unit including a soundboard attached to the frame unit.

According to the mounting structure of the frame unit of the acoustic piano, after the tuning pin burying step in the pin plate, the frame unit processing step, and the supporting column unit assembling step are carried out independently and in parallel, These subsequent assembly procedures can be freely selected. That is, a method of attaching a pin plate that has completed the tuning pin burying step to a column unit and then attaching a frame unit, and attaching the pin plate to the frame unit to form the frame unit according to claim 2, and then the column unit. Or after attaching the frame unit to the column unit,
Since any one of the methods of attaching the pin plate can be freely selected, the degree of freedom in selecting the assembly procedure can be expanded. In addition, this makes it possible to select independent and parallel processes according to the overall production plan and progress of each process, and as a result,
For example, it is possible to widen the degree of freedom in selecting an assembly place such as which process is performed at which place, and to secure the maneuverability of production, which facilitates small-to-medium-volume production and overseas production.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, elements or parts given the same reference numerals have the same configurations and functions unless otherwise specified, and duplicate explanations are omitted.

FIG. 1 shows a frame unit of an upright piano according to a first embodiment of the present invention together with a pin plate connected to the frame unit.

As shown in the drawing, the pin plate 3 has a tuning pin region portion 26 in which the tuning pin 21 is embedded.
And a frame joining region 27 having a fixing bolt hole 28 for joining with the frame 1. The pin plate 3 is made of a hard wood material such as maple wood, beech wood or plywood thereof, and a tuning pin 21 is embedded in the surface of the wood material. The tuning pin 21 is a pin made of a material such as high-grade carbon steel,
It is formed by cutting a fine spiral groove for increasing the rotational friction force and strengthening the holding force, and the upper part is processed into a quadrangle so that a tuning hammer can be inserted, and a hole into which a string is inserted is opened. Since the step of burying the tuning pin 21 is performed by directly driving the tuning pin 21 into a predetermined position of the tuning pin region portion 26, the period required for the step of burying the tuning pin 21 can be significantly reduced as compared with the conventional case. You can At the boundary between the tuning pin area portion 26 and the frame joining area portion 27, a reference line for alignment at the time of joining with the frame unit FU described below may be drawn, or the tuning pin area portion 26 may be a frame joining area portion. It is also possible to add a step projecting forward from 27.

The frame unit FU includes a frame 1 and a hitch pin 2 provided on the lower surface of the frame 1.
And 2. The frame 1 is a high-quality acoustic member containing rare metals and carbon as components, and is composed of a flat plate portion having a wall thickness of about 8 mm to 15 mm and 4 to 7 skeleton portions having a wall thickness of about 20 mm. It is a cast member. The frame 1 is a pin plate 3 after the above-mentioned tuning pin burying process.
(Hereinafter, the pin plate 3 in this state is abbreviated as “pin block PB”) is fixed to the fixing bolt hole 18 by the fixing bolt 8.
Also, it can be attached to the upper part of the back surface of the frame 1 through the fixing bolt hole 28 described above. Also, frame 1
Has an opening 6 opened upwards, and has a pin block PB.
With the attached (see Fig. 2), the tuning pin 2
1 faces the opening 6 from the back surface side. Further, the frame 1 has a fixing bolt hole 19 to be attached to a support plate 7 of a post unit PU described later by a fixing bolt (not shown).

FIG. 5 shows the frame unit F of this embodiment.
FIG. 3 is an assembly process drawing of an upright piano using U, and FIG. 3 shows a mounting structure after the frame mounting process. The assembly procedure of this embodiment will be described below with reference to both drawings.

As shown in FIG. 5, in the assembly process using the frame unit FU of the present invention, first, the following process 1 is performed.
---, 2- and 3- are performed independently and in parallel. That is, 1-A support assembly is assembled from the base 2, support 4, support 40, box 41, support 42, and support plate 7. 1- After mounting the batting 9 on this strut assembly, the sound board 12 to which the sound bar 13 and the piece 16 are adhered is attached to complete the strut unit PU. Step 2-casting the frame 1 and providing the hitch pins 22 and then painting to complete the frame unit FU described above (see FIG. 1B). Step of 3-, drive the tuning pin 21 into the pin plate 3,
The above-mentioned pin block PB is completed (see FIG. 1A). And the process of 1. are performed independently and in parallel.

After that, the following steps are performed by the procedure for connecting (A)-(A) in FIG. Attach the pin block PB to the column unit PU. Next, on the front surface of the pillar unit PU, the pin block P
The frame unit FU is attached so as to sandwich B. Then, the string S is stretched between the tuning pin 21 and the hitch pin 22 via the piece pin 23 (see FIG. 3).

After that, the upright piano is completed by the following steps similar to the above-mentioned conventional assembling step. Next, attach the main board and shelf board, place the keyboard and attach actions, perform tuning and tuning, install the roof, attach case materials such as upper front board and lower front board, and perform sound adjustment finishing and inspection. After that, the assembly is completed (see FIG. 10A).

As described above, in the frame unit FU and its mounting structure according to the first embodiment of the present invention, the frame unit FU has the tuning pin 21 from the opening 6 when the pin block PB is mounted. By facing, the flat plate portion having the tuning pin hole is not necessary in the frame 1, and the material cost and the weight of the frame 1 can be reduced. Further, as a result, since the tuning pin can be directly embedded in the pin plate, the above-mentioned processing work for embedding the tuning pin, which is conventionally required, becomes unnecessary, and the processing cost of the frame 1 can be reduced as compared with the conventional one. In addition to being able to reduce the number, it is possible to shorten the period required for the processing step of the frame 1.

Further, this tuning pin burying step,
That is, the assembly process of the pin block PB (the above-mentioned 3-
Process) and the assembly process of the frame unit FU (2 above)
-Process) and the process of assembling the pillar unit PU (1 above)
Since the steps (1) to (4) can be performed independently and in parallel, there is an effect that the period required for all the steps from the start of column assembly to the inspection can be shortened.
In addition, since each process can be carried out in different places and necessary members can be distributed to each assembly place, the space required for assembly, production equipment,
Also, it has an effect that it becomes easy to secure a storage place for members and the like.

Further, the frame unit FU of this embodiment
Can also be used to select the procedure for connecting (C)-(C) in FIG. 5, and FIG. 4 shows the mounting structure of the frame unit after the frame mounting step at that time.

In the assembling process in this case, (A)-
(A) The procedure of connecting between and the steps of and are reversed,
It looks like this: The other steps are the same as those in the above case. The frame unit FU is attached to the front surface of the column unit PU (see FIG. 4). Next, the pin block PB is inserted and attached between the column unit PU and the frame unit FU from above.

As described above, according to this mounting structure, the frame unit FU is first mounted to the column unit PU,
Then, the pin block PB is attached between the column unit PU and the frame unit FU. The frame unit FU is attached to the front surface of the support plate 7 instead of the pin plate 3 via the fixing bolt hole 19 described above by a fixing bolt. In this case, in the frame unit FU of the present embodiment, as described above, since the frame 1 has the opening 6 that opens upward (see FIG. 1B), after mounting the frame unit FU. However, it is possible to insert the pin block PB from above and attach it between the column unit FU and the frame unit FU by the fixing bolt 8 described above. Also, as shown in the figure,
If the string S is attached to the tuning pin 21 of the pin block PB in advance, the period required for the stringing process after the pin block PB is attached can be shortened.

As described above, if the mounting structure of the frame unit FU is adopted, the step of burying and fixing the tuning pin 21 in the pin plate 3, that is, the step of assembling the pin block PB (the above-mentioned 3- Process),
Steps from the above-mentioned pillar assembly to frame mounting (the above 1-
~, The above 2- and the above) can be independently and in parallel progressed. As a result, since the number of tuning pins is large, it takes time to bury them, and the frame mounting process is performed without waiting for the completion of the tuning pin burying process, which is a factor that prolongs the period required for all processes. By attaching the pin plate that has completed the tuning pin burying process, it is possible to shorten the period required for all the processes from the start of pillar assembly to the inspection.

FIG. 2 is a front view of a frame unit according to the second embodiment of the present invention.

As shown in the figure, the frame unit FU2 is composed of the frame 1 of the frame unit FU of the above-described first embodiment and the pin block PB attached to the upper rear surface thereof. Pin block P
As described above, B is attached by the fixing bolt 8 through the fixing bolt hole 18 and the fixing bolt hole 28. With this configuration, the frame unit FU2 has both the tuning pin 21 and the hitch pin 22, and the tuning pin 21 and the hitch pin 2 are included.
Since the string S can be stretched between the two, it is possible to carry out a part of the process of stringing, which is a post process of mounting the frame in the past. Further, a part of the conventional pre-frame mounting process, that is, the pin plate mounting, can be carried out at the frame assembly place independently of other processes, so that the process at the final assembly place can be reduced. .

In the assembling process using this frame unit FU2, the assembling process of the above-mentioned frame unit FU (the above-mentioned 2) is carried out by the procedure of connecting (B)-(B) in FIG.
-Process) and the assembly process of the pin block PB (3 above)
(-)) Independently and in parallel, and then the process of attaching the pin block PB to the frame unit FU, and the process of assembling the support unit PU (1-
Can be performed independently and in parallel with the steps (1) to (3). In other words, by omitting the above-mentioned machining work for embedding the tuning pin, a process for shortening the period is added to the frame side machining process, and the mounting process for the pin plate that completed the above-mentioned time-consuming tuning pin embedding process is added. By performing the frame attaching step, it becomes possible to balance the period between the assembling step of the column unit PU, which has many constituent members, which easily takes time to assemble, and the frame processing step. Since the period can be adjusted, it becomes possible to shorten the period required for all the steps from the start of the pillar assembly to the inspection.

Furthermore, as described above, the frame units FU, FU2, of the first and second embodiments of the present invention,
If these and their mounting structures are used, the above-mentioned procedure for connecting (A)-(A), (B)-(B), or (C)-(C) shown in FIG. Since it is possible to freely select the procedure for connecting the steps, it is possible to increase the degree of freedom in selection of the assembly procedure and facilitate selection of independent and parallel steps. As a result, for example, total production volume, delivery time, equipment / technical capabilities of each production base, man-hours / skills / labor cost of workers,
Or, considering the convenience of procuring materials / parts, etc., the place of assembly, such as which process among the assembly processes of the above-mentioned pin block PB, frame unit FU, support unit PU, etc. Since it is possible to select relatively freely, it is easy to select and produce these most advantageous regions and countries, and it is also easy to adopt a method such as final assembly in a region close to the consumption region. It is also possible to reduce labor costs and transportation costs. Further, as a result of improving the mobility of production in this way, it is possible to easily cope with small-to-medium-volume production and overseas production.

FIG. 6 is a side sectional view showing an application example of the mounting structure of the frame unit of the present invention when the supporting unit PU2 having a structure different from that of the above-mentioned supporting unit PU is used.

As shown in this figure, the column unit PU2
Then, the girder 40, the box 41, and the girder sticking 42 are omitted from the above-mentioned strut unit PU, and the strut assembly constituting the strut unit PU is composed of only the base 2, the strut 4, and the support plate 7. The assembling process in the case of using this strut assembly is as follows, corresponding to 1- to the assembling process of the strut unit PU described above. The other steps are the same as in the above case. 1- Assemble the pillar assembly from the base 2, the pillar 4, and the support plate 7. 1- After mounting the batting 9 on the strut assembly, the sound board 12 to which the sound bar 13 and the piece 16 are adhered is attached to complete the strut unit PU2.

FIG. 7 is a side sectional view showing a mounting structure similar to that of FIG. 4 when the column unit PU2 is used.

As shown in this figure, according to this mounting structure, the frame unit F is inserted from the front of the column unit PU2.
U or the following frame unit FU3 is attached first, and then the pin block PB is attached from above or behind the column unit PU2. That is, in the case of this mounting structure, the pin block PB can be mounted not only from above as in the above-described mounting structure, but also from the rear because the rear is open. As a result, if the frame 1 has the opening 6 where the tuning pin 21 faces from the back surface side, the pin block may be applied from the rear side after the frame attaching process even if the upper portion is not opened (see FIG. 8B). PB can be attached. Therefore, the above-mentioned frame unit FU
It is possible to use the frame unit FU3 shown in FIG.

In the mounting structure using the column unit PU2 described above, in addition to the effect obtained when the column unit PU is used, the girder 40, the box 41 and the girder stick 42 are provided.
As a result, the number of constituent parts can be reduced, the material cost and the processing cost can be reduced, and the number of joints between members, which are apt to be a weak point in strength, can be reduced. Further, the joint surface between the strut unit PU2 and the pin block PB is the lower surface of the pin plate 3, and in the case of the upright piano, the tension of the strings S acts in the vertical direction, so that the joint surface is horizontal, It is structurally advantageous over Further, even if the pin plate 3 is formed to have a sufficient thickness to fix and support the tuning pin 21, it can be offset by the thickness of the support column 4 and the distance between the string S and the support column 4 can be shortened. As a result, since the thickness of the batting 9 can be set to the minimum necessary thickness for giving a sound to the soundboard 12, a thick material is not required, the material cost can be reduced, and the support 4 Even if a thickness giving sufficient strength is secured, the overall thickness can be made smaller than the conventional one, and the depth dimension of the piano, that is, the installation area can be reduced.
Since the pin block PB can be attached from the rear side as described above, there is an advantage that the frame unit FU3 in which the upper portion of the frame unit FU is reinforced by the upper skeleton portion 17 can be used.

The present invention is not limited to the embodiment described above, and can be implemented in various modes. For example, the target acoustic piano is
Not only an upright piano, but a grand piano is also acceptable. That is, by using the same frame 1 as shown in FIG. 1 (b) or FIG. 8 (b), when a pin block is attached to the back surface, the frame has an opening from which the tuning pin faces from the back surface side. A frame unit similar to the frame unit FU or the frame unit FU2 described above can be used. In particular, in the case of a grand piano, since the strut assembly composed of loading and the like and the pin plate are separated, there is no need to specially devise as a strut unit, which is advantageous over the upright piano. In addition, the support unit is replaced by the frame 1 instead of the support plate 7.
The supporting plate 7 can be dispensed with if the joint portion of is extended and attached directly to the box 41 or the like (see FIG. 3).
And FIG. 4). Further, the mounting method between the frame unit and the pin block is not limited to the fixing bolt shown in the embodiment, but may be a method using an adhesive,
You may use them together. Furthermore, between the column unit and the pin block, in addition to fixing bolts, adhesives, their combined use, etc., depending on the required strength, various joint construction methods such as nails, other joint metal parts, and combinations thereof are selected. Can be joined together. In addition, the detailed configuration, the mounting method, and the like are appropriately set without departing from the spirit of the present invention.
It is possible to change.

[0038]

As described above in detail, the frame unit for an acoustic piano and the mounting structure thereof according to the present invention do not require a flat plate portion having a tuning pin hole for penetrating a tuning pin in the frame, so that There is an effect that the material cost can be reduced and the weight can be reduced. In addition, since the frame machining process does not require a machining work for embedding the tuning pin, the machining cost can be reduced and the period required for the frame machining process can be shortened. Furthermore, the steps of burying tuning pins can be performed independently and in parallel without waiting for the completion of other steps such as strut assembly, which has the effect of increasing the degree of freedom in selecting assembly procedures. ing. Also, with these, it is possible to shorten the period required for the entire process from the start of pillar assembly to inspection, and since the assembly locations can be distributed, the space required for assembly, production equipment, and the storage location for parts It has the effect of making it easier to secure such items.

[Brief description of drawings]

1A is a front view of a pin plate after a tuning pin burying step according to an embodiment of the present invention, and FIG. 1B is a front view of a frame unit according to a first embodiment of the present invention.

FIG. 2 is a front view of a frame unit according to a second embodiment of the present invention.

FIG. 3 (a) is a side sectional view showing an example of an upright piano as an example of a frame unit mounting structure of the present invention, and FIG. 3 (b) is a side showing a state in which a tuning pin is embedded at that time. FIG.

FIG. 4 is a side sectional view showing a mounting structure of a frame unit after a frame mounting step in the case of a procedure for connecting between (C) and (C) in FIG.

FIG. 5 shows a case where the frame unit of the present invention is used,
It is an assembly process drawing of an acoustic piano.

6 is a side cross-sectional view similar to FIG. 3 when a strut unit having a configuration different from that of FIG. 3 is used.

7 is a side sectional view similar to FIG. 4, when the strut unit of FIG. 6 is used.

8 is a front view similar to FIG. 1 in the case of a frame unit in which the upper portion of the frame unit of FIG. 1 (b) is reinforced.

FIG. 9 is an assembly process diagram of a conventional acoustic piano.

FIG. 10 (a) is a side sectional view of a conventional upright piano after assembly, and FIG. 10 (b) is a side sectional view showing a state in which a tuning pin is embedded at that time.

FIG. 11 is a front view of a frame unit of a conventional upright piano.

[Explanation of symbols]

 FU frame unit FU2 frame unit FU3 frame unit PU struts unit PU2 struts unit 1 frame 2 base 3 pin board 4 struts 6 openings 9 turning 12 soundboard 21 tuning pin 22 hitch pin

Claims (3)

[Claims] 1. A frame having a pin plate on which a tuning pin is projectingly formed so as to be attachable to a back surface thereof, the frame having an opening facing the tuning pin from the back surface side when the pin plate is attached, and the frame. A frame unit for an acoustic piano, which is provided on the surface of the and has a hitch pin capable of stringing between the tuning pin and the tuning pin. 2. Attached to the back surface of the frame,
The frame unit for an acoustic piano according to claim 1, further comprising a pin plate in which a tuning pin is embedded and fixed. 3. A front surface of a pillar unit comprising a base, a pillar vertically fixed to the base, a batting attached to a front surface of the pillar, and a soundboard attached to a front surface of the batting. A frame unit mounting structure for an acoustic piano, wherein the frame unit according to claim 1 or 2 is fixed to the side.