JPH04190295A - Supporting structure for tuning pin - Google Patents

Abstract

PURPOSE:To facilitate the regulation of pin torque by connectedly providing a tuning pin having a tapered part fitting in a tapered hole with a fastening force adjusting section through which axial fastening force for a bush can be adjusted. CONSTITUTION:In the case of fixing a tuning pin 16 to a frame 11, a bush 13 is driven into the fitting hole of the frame 11 for fixing it, and the pin 16 is inserted from upside in an inserting hole to bring the outer wall face of its tapered part 16c into contact with the inner wall face of a tapered hole 14, and the thread part of the pin 16 is protruded below the frame 11, and then fastened by a nut 20 through a spacer 18 and a washer 19 so tight as to obtain required pin torque. Thus the pin torque can be easily regulated. One end of a string 17 is then wound round the pin 16 for supporting the string 17.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a tuning pin support structure in which a bushing with a tapered hole is fitted to a frame, and a tuning pin having a tapered portion is fitted into the bushing. By adjusting the tightening force in the fitting direction, the tuning pin torque can be adjusted without changing the frame specifications of current pianos.

<Prior Art> In the conventional tuning pin support structure, a hole is drilled in a pin plate having a laminated structure, and a tuning pin having a fine thread cut on the outer surface is driven into the hole.

The tuning pin secures a predetermined pin torque by interference fit with the pin plate, that is, by friction between the finely threaded portion and the inner wall surface of the hole in the pin plate.

In this way, the pin plate maintains the frictional force between it and the tuning pin at the required value to ensure smooth rotation of the tuning pin and sufficient torque to hold the tuned string. is required to do so. Furthermore, the support structure for this tuning pin is required to have strength that can withstand the tension of the strings.

Conventionally, the following techniques have been proposed as techniques capable of adjusting the bin torque of the tuning pin while satisfying these conditions.

That is, there is one described in Japanese Utility Model Publication No. 52-50783. In this product, a screw hole, a tapered hole, and a straight hole are provided in a metal bin plate from the back side to the front side. The tuning pin that fits into the tapered hole and the straight hole passes through the bin plate and has its tip protruding from the straight hole. Furthermore, the tuning pin is pressed from the back side by bringing the tip of a screw screwed into the tapped hole from the back side of the bin plate into contact with the tapered hole fitting portion of the tuning pin.

Also, in U.S. Patent No. 4,920,847,
Directly (without intervening bin plate) by inserting a tuning pin with a threaded part into the hole in the frame.
A technique is disclosed in which the lubricant is provided through the frame and tightened with nuts from both the front and back sides of the frame via a lubricating member.

<Problems to be Solved by the Invention> However, in the former technique, a special metal bin plate attached to the frame is required to mount the tuning pin, which requires modification of the piano. In particular, it was necessary to modify the current frame. For this reason, the ease of mounting has deteriorated.

Further, since the tuning pin and the screw that presses and biases the tuning pin are separate members and are in point contact with each other, the accuracy of holding the tuning torque (bin torque) and making fine adjustments has been reduced.

Also, considering the mounting condition when the tuning pins are installed, especially for the tuning pins in the middle part of a grand piano, the spacing between each tuning pin is narrow, and the presence of a threaded portion larger than the diameter of the tuning pin makes it difficult to install the tuning pin. It was making it difficult.

Furthermore, when providing a female thread on the bin plate, a problem has arisen in terms of mechanical strength. Due to mounting considerations, it is not possible to increase the thread diameter, and on the other hand, if the pitch of the threads on the female side is small, there is a high possibility of damage.

On the other hand, in the latter conventional technique, tightening the nuts from both the upper and lower sides of the frame required work, and it was difficult to adjust the bolt torque.

Further, since the structure was fixed with a nut via a lubricating member, it was difficult to achieve both a holding force against string tension and a tuning torque adjustment function.

That is, in a structure in which nut tightening depends only on force and the lubricating properties of the lubricating member, weather resistance (for example, resistance to changes in temperature and humidity) and reliability are reduced.

Therefore, the present invention provides a tuning pin support that allows easy adjustment of pin torque, has excellent mounting performance on a frame, improves assembly accuracy and workability, and is highly reliable even for long-term use. The purpose is to provide structure.

<Means for Solving the Problems> The present invention provides a bushing that has a tapered hole extending in the axial direction and is fitted and supported by a frame of a piano, and a tapered portion that fits into the tapered hole. It also has a tightening force adjuster that can adjust the tightening force in the axial direction to the bushing.
This is a tuning pin support structure including a tuning pin in which JfM3 are arranged in series and one end of a string stretched around the frame of the piano is wound around and supported.

<Function> Regarding the support structure of the tuning pin according to the present invention,
The tension of the string is adjusted by rotating the tuning pin relative to the bushing.

Then, when the axial tightening force on the bushing is adjusted using the tightening force adjustment section of the tuning pin, the pressing force (frictional force) that acts between the outer surface of the tapered portion of the tuning pin and the inner wall surface of the tapered hole into which it fits. ) can be adjusted. As a result, the bin torque of the tuning pin is adjusted.

<Example> Hereinafter, an example of a tuning pin support structure according to the present invention will be described with reference to the drawings.

Measure 1: Figures 1 and 2 show a tuning pin support structure according to a first embodiment of the present invention.

In these figures, reference numeral 11 denotes a piano frame, and a fitting hole 12 is formed in this frame 11.

The fitting hole 12 has a circular opening area of a constant size, and is bored in the thickness direction of the frame 11.

A bushing 13, which is a cylindrical body, is driven into the fitting hole 12, and is fitted and fixed therein. This bushing 13 is fixed to the frame 11 by tight fitting. 1
3A is a flange portion of the bushing 13 for positioning in the height direction (keeping it at a constant height).

An insertion hole into which a tuning pin is inserted is formed in the bush 13 so as to extend along the axial direction. The insertion hole has a larger opening on the upper end side in the figure, a smaller opening on the lower end side, and is generally formed in a generally tapered shape. In other words, the insertion hole is a straight hole made of a tapered hole portion 14 formed by a tapered inner wall surface and the same cross section with the same diameter as the minimum diameter portion (lower end side portion in the figure) of this tapered hole portion 14. It has a hole 15.

The angle of inclination of the tapered inner wall surface (inclined surface) of the tapered hole portion 14 with respect to the axis is set to an arbitrary angle of 1° to 10°, for example.

The tuning pin 16 is made of a hard steel wire rod, for example, and is fixed upright to the frame 11 by being fitted into the insertion hole (14° 15) of the bushing 13.

As shown in the drawing, the tuning pin 16 is formed to have a large diameter portion 16A at its upper end, a threaded portion 16B at its lower end, and a tapered portion 16C at its intermediate portion.

The large diameter portion 16A has a diameter that is the same as or slightly larger than the diameter of the upper end opening of the tapered hole portion 14 of the insertion hole, and is formed to a predetermined length, and has one end of the string 17 at that portion (cylindrical portion). is wrapped around it.

The threaded portion 16B is a male screw threaded on the outer surface of the lower end of the tuning pin 16, and is formed to have a smaller diameter than the diameter of the lower end opening of the straight hole portion 15 of the insertion hole, and when fitted, 11 by a predetermined length (see FIG. 2).

The tapered portion 16C that connects the large diameter portion 16A and the threaded portion 16B is formed at an angle of 1°, which is the same as the inner wall surface of the tapered hole 14, so that the outer wall surface fits tightly into the inner wall surface of the tapered hole 14. It is formed with an inclination of ~10°.

Note that the tapered portion 16C of these tuning pins 16
The outer wall surface of the tuning pin 16 and the inner wall surface of the tapered hole 14 of the bushing 13 are both tapered surfaces by adjusting the surface roughness or by applying or impregnating a lubricant or the like to ensure smooth rotation of the tuning pin 16. It is desirable to process it to allow movement.

The tuning pin 16 is inserted into the insertion hole, passes through it, and is fixed to the frame 11, but this fixation is achieved by applying a predetermined frictional force between the inner wall surface of the tapered hole portion 14 of the insertion hole and the tapered portion 16C. It is done so that it acts on the contact surface.

Therefore, a ring-shaped spacer 18 is attached to the threaded portion 16B.
, the first nut 20 and the second nut 21 (lock nuts) are tightened with the washer 19 in between until the required bolt torque is obtained.

The purpose of this double nut structure is to prevent the nut 20 from loosening.

However, the spacer 18 is made of a self-lubricating material, such as a resin such as Teflon or polyacetal, to ensure smooth sliding on the lower surface of the bushing 13.

These threaded portions 16B, spacers 181, and washers 19
, nuts 20 and 21 as a whole can adjust the pressing force acting on the tuning pin 16 on the sliding surfaces (the inner wall surface of the tapered hole 14 and the outer surface of the tapered portion 16C), that is, the It constitutes an adjustment mechanism that can adjust the frictional force between the members 13, 16. And screw part 1
Reference numeral 6B constitutes a tightening force adjustment portion that can adjust the axial tightening force of the tuning pin 16 against the bush 13.

Therefore, this tuning pin 16 is connected to the frame 11.
To fix it, first, the bushing 13 is driven into the fitting hole 12 of the frame 11 and fixed.

Then, the tuning pin 16 is set on the bushing 13. Specifically, the threaded portion 16 of the tuning pin 16
B is inserted into the insertion hole from above to bring the outer wall surface of the tapered portion 16C into contact with the inner wall surface of the tapered hole portion 14. Threaded part 16
B projects below the bushing 13 and frame 11.

Further, the height of the tuning pin 16 from the frame 11 is kept constant due to the sliding contact between the tapered portion 16C and the inner wall surface of the tapered hole portion 14 of the insertion hole.

Then, the threaded portion 16B is tightened using the first nut 20 via the spacer 18 and washer 19 until the required bolt torque is obtained.

When the required bottle torque is obtained, the second nut 21
is tightened onto the threaded portion 16B to prevent the nut 20 from loosening. For example, this bottle torque is ] 60 (
kg-am) is required.

After that, connect one end of the string 17 to the tuning pin 16.
The string 17 is supported by being wrapped around the large diameter portion 16A of the string 17.

To adjust the tension of the string 17 in the above condition, fit a tuning hammer (not shown) into the square part at the top of the large diameter part 16A and rotate it around the axis (arrow in Figure 2). turn. As a result, the tuning pin 16 is connected to the spacer 18.
, the washer 19, the nut 20, and the nut 21, it rotates with respect to the frame 11 and the bush 13, and can adjust the vertical position.

Note that, as described above, since the tuning pin 16 was directly implanted in the frame 11 via the bush 13, that is, the pin plate was removed, it was possible to expand the mounting space inside the piano.

Figures 3 and 4 show a second embodiment of the present invention.

In this embodiment, a bushing 13 is driven into a fitting hole 12 formed in a frame 11 from below. The other configurations are the same as those of the above embodiment.

In this embodiment, as shown in FIG. 4, the flange portion 13A of the bushing 13 does not protrude from the front side of the frame 11. Therefore, the bushing 13 can be press-fitted without damaging the surface-treated portion of the frame 11, such as gold powder coating, during processing. Also, as with current pianos, the cylindrical head of the bushing 13 is visible in the fitting hole 2 (pin hole) of the frame 1.
Its appearance is excellent. Moreover, its durability and reliability are also excellent.

Note that during maintenance, for example, in the case of a grand piano, the force for tightening the nut can be adjusted by pulling out the action.

On an upright piano, the roof can be opened and the force of tightening the nuts can be adjusted.

<Effects of the Invention> As described above, according to the present invention, the tuning pin is attached via the bushing, and the axial tightening force on the bushing is adjusted from one side by the tightening force adjusting portion of the tuning pin. Therefore, the bin torque can be easily adjusted.

Furthermore, since the tuning pin is fitted onto the bush using a tapered surface, the height of the tuning pin head can be easily adjusted. Even if the tuning pin is rotated to adjust the slack tension, the height of the head does not change. In other words, the accuracy of morning stand and its workability are improved.

In addition, there is no need to attach tuning pins through a special pin plate, etc., and there is no need to modify the frame.Furthermore, it can be directly attached to the current frame (and the pin plate can be removed), and its implementation Excellent in sex. Furthermore, by removing the pin plate, the mounting space inside the piano body can be expanded.

Additionally, since the pin plate has been removed, each tuning pin can be repaired and adjusted individually. In addition, conventional screws for adjusting the pin torque are unnecessary, and this tuning pin can be installed and adjusted even in places where the distance between the pin and the pin is narrow, such as in the middle part of a grand piano. I can do it.

Furthermore, it has excellent weather resistance and is highly reliable for long-term use. It is also possible to adjust the tension of the string over time.

[Brief explanation of the drawing]

FIG. 1 is an exploded side sectional view showing a tuning pin support structure according to a first embodiment of the present invention, FIG. 2 is a side sectional view showing a tuning pin support structure according to the first embodiment, and FIG. FIG. 4 is an exploded side sectional view showing a tuning pin support structure according to a second embodiment of the present invention, and FIG. 4 is a side sectional view showing a tuning pin support structure according to the second embodiment. 11......Frame, 12...Fitting hole (pin hole), 13...
・・・・・・・・・Bush, 14・・・・・・・・・Taber hole, 16・・・・・・
...Tuning pin, 16B...
・Threaded part OR force adjustment part), 16C...Taber part, 17......Strings. Patent Applicant: Yamaha Corporation Agent, Patent Attorney Kiyoshi Kuwai Cross section 222F-18 1 □ ] -20 21-Eco Fig. 3 Disassembled side sectional view of the 2nd circular example Fig. 4

Claims (1)

[Claims] A bush having a tapered hole extending in the axial direction and fitted and supported by the frame of the piano, and a tapered part fitting into the tapered hole, and an axis for the bush. A tuning pin characterized in that the tuning pin is provided with a tightening force adjustment section that can adjust the tightening force in the direction, and that wraps and supports one end of the string stretched on the frame of the piano. Support structure.