JP2018005159A - Looseness stopper of drum head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a looseness stopper of a drum head capable of preventing the looseness of a lag bolt at a low cost with a simple structure, capable of being mounted without removing the lag bolt, small in contact area to the lag bolt and a hoop, and suppressing the influence to an acoustic performance.SOLUTION: A looseness stopper of a drum head includes: a body plate part 22 having a rotation stop hole 21 pushed into an angle head part 8a of a lag bolt 8; a support plate part 25 having a gap 24 communicating a support hole 23 in contact with an axis part 8b of the lag bolt 8 and an outside and an inside of the support hole 23; and a center plate part 26 connecting the support plate part 25 and the body plate part 22. The body plate part 22, the center plate part 26, and the support plate part 25 are integrally formed from a resin plate material having flexibility. The rotation stop hole 21 is pushed into the angle head part 8a of the lag bolt 8. The gap 24 is extended by the twisting of the center plate part 26 so that the support plate part 25 is spread in a J letter shape, and the spread part of the support hole 23 is tied up by the axis part 8b of the lag bolt 8.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a drum head locking device for suppressing loosening of a drum head mounted as a vibrating membrane in an opening of a cylindrical drum shell.

  FIG. 1 is a perspective view of a drum (snare drum) 1, and FIG. 2B is a partial side sectional view of the drum 1. As shown in the figure, the drum 1 includes a cylindrical drum shell 2, a drum head 3 as a vibration film that covers the opening of the drum shell 2, and an annular hoop 4 that holds the drum head 3 on the drum shell 2. I have. The drum 1 includes a tom tom and a floor tom in addition to the snare drum.

  A lug (bolt fixing device) 5 is provided at a side portion of the drum shell 2 at intervals in the circumferential direction, and a lug nut 6 is attached to the lug 5. An annular head frame 3 a is provided on the outer periphery of the drum head 3. A rim portion 4a is formed on the outer peripheral portion of the hoop 4, and bolt insertion holes 7 are provided in the rim portion 4a at intervals in the circumferential direction. A lug bolt (tension bolt) 8 is inserted into the bolt insertion hole 7, and the lug bolt 8 is screwed into the lug nut 6. By this screwing, the head frame 3 a is pressed against the hoop 4, the drum head 3 is pressed against the opening of the drum shell 2, and tension is applied to the drum head 3.

  A square head 8 a is formed on the head of the lug bolt 8. By adjusting the degree of screwing of the lug bolt 8 to the lug nut 6 by rotating the square head 8a with a dedicated tool (tuning key), the tension of the drum head 3 is changed and the pitch of the drum head 3 is adjusted (tuning) )I do. The pitch once tuned is held by the thread of the lug bolt 8 being pressed against the screw hole of the lug nut 6 in the bolt axial direction by the tension of the drum head 3.

  By the way, the drum head 3 is hit with a stick or the like during performance. When the impact or vibration due to the hit is transmitted to the hoop 4 or the drum shell 2, the lag bolt 8 vibrates slightly in the bolt axial direction, and the lag bolt 8 Gradually loosens and the pitch of the tuned pitch drops. In particular, the stronger the striking force, the greater the vibration, the more easily the lag bolt 8 loosens, and the lower the pitch.

  In addition, unlike a normal head shot in which only the drum head 3 is hit, in an open rim shot in which the drum head 3 and the hoop 4 are simultaneously hit with a stick, the hoop 4 sinks at the moment the hoop 4 is hit, At that moment, since the lug bolt 8 is in a free state, the looseness of the lug bolt 8 becomes remarkable.

  In this way, when the lag bolt 8 is loosened by the impact and the pitch of the drum head 3 once tuned is lowered (pitched down), the pitch of the drum 1 as a constituent sound with respect to the entire music is disturbed, resulting in incongruity.

  Conventionally, various inventions have been proposed to prevent loosening of the lug bolt 8. For example, in Patent Document 1, the lug bolt 8 has a hollow structure in which a hole along the axial direction is formed inside, a slit is formed in the bolt shaft portion in the axial direction, and a rod-shaped metal core is inserted into the hole. The drum head fixing mechanism in which the slit is widened and the thread of the shaft portion of the lug bolt 8 is pressed against the screw hole of the lug nut 6 to prevent the lug bolt 8 from loosening is disclosed.

JP 2014-190989 A

  By the way, the drum head fixing mechanism disclosed in Patent Document 1 uses a rug bolt having a complicated and special structure, and there are a large number of parts that require high accuracy, and an increase in cost is inevitable. To explain this point, for example, in the case of a snare drum, the drum head 3 is usually attached to the opening of the cylindrical drum shell 2 by lug bolts of about 8 to 10 on one side and about 16 to 20 on both sides in total. Is done. In the case of a tom tom, usually about 4 to 8 lug bolts are used on one side, and in the case of a floor tom, about 6 to 8 lug bolts are usually used on one side. For this reason, a large number of expensive lug bolts having a complicated and special structure must be used for one drum 1, and a large cost is required. Therefore, development of an inexpensive locking device that can prevent loosening of the lug bolt 8 with a simple structure is desired.

  As shown in FIG. 2 (a), as a lug bolt 9 for a lug bolt 8 which has a simple structure and reduced cost, a pair of rubber plates 9a having a thickness of about 1.5 mm are spaced apart by a distance of about 9 mm. A device in which holes 9b and 9c are formed (Drum Bolt Stop manufactured by The Hand Company EU) is known. As shown in FIG. 2 (b), the locking device 9 is tuned by rotating the square head 8 a of the lug bolt 8 with one hole 9 b of the rubber plate 9 a inserted through the shaft portion of the lug bolt 8. Thereafter, the rubber plate 9a is pulled to push the other hole 9c into the corner head 8a of the lug bolt 8, and the outer periphery of the rim portion 4a of the hoop 4 is pressed between the hole 9b and the hole 9c of the rubber plate 9a. The rotation of the corner head 8a of the lug bolt 8 is prevented.

  However, since the hole 9c that is pushed into the corner head 8a of the lug bolt 8 is formed in the rubber plate 9a, the loose stop 9 can stop the rotation that instantaneously occurs in the lug bolt 8 when the drum head 3 is hit. Inability to do so can result in poor tuning. In addition, a rubber plate (rubber plate 9a), which is a material having high vibration absorption, is in contact with a wide area so as to cover the corner head 8a and the shaft portion of the lug bolt 8 and the outer periphery of the rim portion 4a of the hoop 4. The vibration of the drum 1 as a musical instrument is suppressed, and the acoustic performance is impaired. Further, in order to insert the hole 9b of the rubber plate 9a into the shaft portion of the lug bolt 8, the lug bolt 8 must be removed from the lug nut 6. Therefore, it cannot be said that the mountability is good. Need to retune.

  If a cut (slit) 9d that communicates the inside and outside of the hole 9b is formed in the rubber plate 9a, the slit 9d can be inserted into the shaft portion of the lug bolt 8 without removing the lug bolt 8, but the lug bolt 8 If the other hole 9c is attached to the square head 8a while the rubber plate 9a is pulled to such an extent that the square head 8a can be prevented from rotating, the shaft portion of the lug bolt 8 will come off from the slit 9d, which is technically established. do not do.

  The purpose of the present invention, which was created in view of the above circumstances, is to prevent the loosening of the lug bolts with a simple structure and at low cost, can be mounted without removing the lug bolts, and the contact area to the lug bolts and hoops is small, leading to acoustic performance. An object of the present invention is to provide a drum head locking device that suppresses the influence of the above.

  According to the present invention created to achieve the above object, a cylindrical drum shell, a drum head that covers the opening of the drum shell, an annular hoop that holds the drum head on the drum shell, and a hoop are formed. Bolt insertion holes, lug nuts supported on the side of the drum shell, lug bolts that are inserted into the bolt insertion holes and screwed into the lug nuts to press the drum head against the drum shell opening via the hoop, and lug bolts A drum head locking device for a drum having a corner head formed on the head of the lug bolt, and a main body plate portion having a stop hole to be pushed into the corner head of the lug bolt, and a shaft portion of the lug bolt A support plate having a break that communicates the inside and outside of the support hole and the support hole, and a central plate that connects the support plate and the main plate, the main plate, the central plate, and the support plate, It is integrally formed from a flexible resin plate, and the outer edge of the cut is located between the stop hole and the support hole, and the stop hole of the main body plate part is relative to the corner head of the lug bolt. In a state where it is pushed non-rotatably, at least one of the central plate portion and the support plate portion is twisted, so that the cut is widened and the support plate portion is developed in a J shape, and the support hole portion of the developed support plate portion The drum head is characterized in that the shaft portion of the lug bolt is entangled with the shaft portion of the lug bolt and the tanged support hole portion is pressed against the shaft portion of the lag bolt by the restoring force of torsion. A locking device is provided.

  In the drum head locking device according to the present invention, the support plate portion is integrally provided with a claw plate portion formed so as to protrude on the same plane, and the claw plate portion includes the central plate portion and the support plate. It may be pressed against the shaft portion of the lug bolt by the restoring force of torsion generated by twisting at least one of the portions.

  In the drum head locking device according to the present invention, the main body plate portion is provided with a mark indicating an appropriate mounting angle of the main body plate portion with respect to the hoop when the rotation hole of the main body plate portion is pushed into the corner head of the lug bolt. May be.

According to the drum head locking device of the present invention, the following effects can be exhibited.
(1) Since the main body plate portion, the central plate portion, and the support plate portion are integrally formed from a flexible resin plate material, the structure is extremely simple and low cost by punching or the like. Can be manufactured.
(2) With the rotation hole of the main body plate portion pushed into the corner head of the lug bolt, at least one of the central plate portion and the support plate portion is twisted, so that the break of the support hole is widened and the support plate portion is J Since the portion of the support hole of the support plate portion that is developed in a letter shape is entangled with the shaft portion of the lug bolt, it can be mounted without removing the lug bolt.
(3) The outer end of the cut is located between the rotation stop hole and the support hole, and the cut is caused by the restoring force of the twist generated by twisting at least one of the resin center plate and the support plate. Since the portion of the support hole developed from is pressed against the shaft portion of the lug bolt, it is possible to prevent the shaft portion of the lug bolt from coming off from the cut.
(4) The rotation hole of the resin-made main body plate portion was pushed into the corner head of the lug bolt so as not to be relatively rotatable, and the support hole portion of the support plate portion developed from the cut was entangled with the shaft portion of the lug bolt. In this state, since the central plate portion is brought into contact with the hoop, loosening of the lug bolt can be suppressed.
(5) Since at least one of the resin center plate portion and the support plate portion is twisted, the planar locking device is three-dimensionalized, and the three-dimensional center plate portion comes into contact with the hoop. The contact area can be made as small as possible, and since the material is a resin harder than rubber, the influence on the acoustic performance can be suppressed.
(6) In summary, according to the drum head locking device of the present invention, the lug bolt can be prevented from loosening with a simple structure at low cost, and can be mounted without removing the lug bolt, and the contact area to the lug bolt and hoop is increased. The influence on the acoustic performance can be suppressed small.

It is a perspective view which shows the outline | summary of a drum (snare drum). (A) is a top view which shows the conventional locking device, (b) is a fragmentary sectional side view of the drum with which the locking device was mounted | worn. It is a partial sectional side view of the drum equipped with the loose fastener for press hoops according to the first embodiment of the present invention and the loose fastener for die cast hoops according to the second embodiment. It is a top view of the loose stop for press hoops concerning a 1st embodiment of the present invention. It is a perspective view which shows the 1st process of mounting | wearing the drum with the said locking device. It is a perspective view which shows the following 2nd process. It is a perspective view which shows the 3rd process (mounting completion) which follows. It is the perspective view which looked at FIG. 7 from the other side. It is a top view of the loosening stop tool for die-casting hoops concerning a 2nd embodiment of the present invention. It is a perspective view which shows the 1st process of mounting | wearing the drum with the said locking device. It is a perspective view which shows the following 2nd process. It is a perspective view which shows the 3rd process which continues. It is a perspective view which shows the 4th process (mounting completion) which follows.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Outline of drum 1)
FIG. 1 is a perspective view of a drum (snare drum) 1, and FIG. 3 is a partial side sectional view of the drum 1. As shown in the figure, the drum 1 includes a cylindrical drum shell 2, a drum head 3 as a vibration film that covers the opening of the drum shell 2, and an annular hoop 4 that holds the drum head 3 on the drum shell 2. I have. The drum 1 includes a tom tom and a floor tom in addition to the snare drum.

  As shown in FIG. 3, lugs (bolt fixing devices) 5 are attached to the side portions of the drum shell 2 with screws 10 at intervals in the circumferential direction, and lug nuts 6 are attached to the lugs 5. An annular head frame 3 a is provided on the outer periphery of the drum head 3. A rim portion 4a is formed on the outer peripheral portion of the hoop 4, and bolt insertion holes 7 are provided in the rim portion 4a at intervals in the circumferential direction. A lug bolt (tension bolt) 8 is inserted into the bolt insertion hole 7 via a washer 11, and the lug bolt 8 is screwed into the lug nut 6. By this screwing, the head frame 3 a of the drum head 3 is pressed against the hoop 4, the drum head 3 is pressed against the opening of the drum shell 2, and tension is applied to the drum head 3. The head of the lug bolt 8 is formed with a square head 8 a for adjusting the degree of screwing to the lug nut 6 and adjusting (tuning) the pitch of the drum head 3.

  In the drum 1 shown in FIGS. 1 and 3, a press hoop 4 x is used for the upper hoop 4, and a die cast hoop 4 y is used for the lower hoop 4. The press hoop 4x is the most common hoop made of press-formed steel, and the dimension of the rim portion 4a where the lug bolt 8 is inserted is smaller than that of the die-cast hoop 4y. As the press hoop 4x, a “drum head locking device” 20 according to a first embodiment to be described later is used. On the other hand, the die-cast hoop 4y is a die-cast hoop, and is made of zinc, aluminum, brass (brass), etc., and the dimension of the rim portion 4a where the lug bolt 8 is inserted is larger than that of the press hoop 4x. Is also big. As the die cast hoop 4a, a “drum head loosening stop” 30 according to a second embodiment to be described later is used.

(First Embodiment: Loosening Stopper 20 of Drum Head 3)
The “drum head loosening stop” 20 according to the first embodiment of the present invention will be described with reference to FIGS. The locking device 20 is used for a press hoop 4x (upper hoop in FIG. 3). As shown in FIG. 4, the locking device 20 according to the first embodiment includes a main body plate portion 22 having a rotation stop 21 that is pushed into the corner head portion 8 a of the lug bolt 8, and a support that contacts the shaft portion 8 b of the lug bolt 8. A support plate portion 25 having a slit (slit) 24 that communicates the inside and outside of the hole 23 and the support hole 23, and a central plate portion 26 that connects the support plate portion 25 and the main body plate portion 22. The center plate portion 26 and the support plate portion 25 are integrally formed from a plate material made of a flexible resin (for example, polyethylene, polyvinyl chloride, polypropylene, etc.). The width of the cut (slit) 24 may be about 1 mm.

  A mark (arrow) 27 for indicating the mounting angle of the main body plate portion 22 with respect to the hoop 4 (press hoop 4x) when the rotation stop hole 21 is pushed into the corner head portion 8a of the lug bolt 8 is provided on the main body plate portion 22. It is provided along the radial direction of the stop hole 21. The outer end 24a of the cut 24 is located in a region between the rotation hole 21 and the support hole 23, and at least one of the center plate portion 26 and the support plate portion 25 is twisted to widen the cut 24. When this occurs, the support plate portion 25 is developed in a J-shape. The above-mentioned region where the outer end 24a of the cut 24 is located is a line connecting the center of the rotation hole 21 and the center of the support hole 23, and a line passing through the center of the rotation hole 21 perpendicular to the line A. B, where C is a line orthogonal to the line A and passing through the center of the support hole 23, it is an area between the line B and the line C.

  The cut 24 is formed in a curved shape so as to be smoothly connected to the inner peripheral surface of the support hole 23 and to make the width of the central plate portion 26 constant. As shown in FIGS. 5 to 8, the central plate portion 26 is formed. When at least one of the support plate portion 25 is twisted and the cut 24 is widened, the central plate portion 26 is brought into contact with the outer peripheral end of the rim portion 4a of the hoop 4 by the restoring force of the torsion. Specifically, the central plate portion 26 is formed in a curved shape, and the plate thickness portion 26a on the inner surface side of the curve is brought into contact with the outer peripheral end of the rim portion 4a of the hoop 4 by the restoring force of the torsion. The support plate portion 25 is integrally provided with a claw plate portion 28 formed so as to protrude on the same plane. The claw plate portion 28 is pressed against the shaft portion 8b of the lug bolt 8 by a torsional restoring force generated by twisting at least one of the central plate portion 26 and the support plate portion 25.

  The inner diameter of the stop hole 21 shown in FIG. 4 is determined according to the size of the corner head 8a of the lug bolt 8, but is 5.5 mm in this embodiment. The inner diameter of the support hole 23 is determined according to the diameter of the shaft portion 8b of the lug bolt 8, but is 5.5 mm in this embodiment. Further, the distance between the center of the rotation hole 21 and the center of the support hole 23 is 20 mm, the lateral width of the central plate portion 26 is 3.5 mm, the lateral width of the main body plate portion 22 is 14.5 mm, and the lateral width of the support plate portion 25 is 13. .5 mm, the overall length of the locking device 20 is 33.5 mm, and the plate thickness is 1.5 mm. The line A connecting the center of the rotation hole 21 and the center of the support hole 23 and the center of the nail plate portion 28 The angle with the line connecting with the center of the support hole 23 is 55 degrees. These numerical values are illustrative and are not limited.

(Installed)
The loose fastener 20 according to the first embodiment shown in FIG. 4 is attached to the upper hoop 4 (press hoop 4x) shown in FIG. 3 as described below. First, as shown in FIG. 5, the rotation stop 21 of the resin main body plate portion 22 is pushed into the corner head 8 a of the lug bolt 8 so as not to be relatively rotatable. At this time, the mounting angle of the main body plate portion 22 with respect to the hoop 4 is set to an appropriate angle by directing the mark (arrow) 27 of the main body plate portion 22 toward the center of the hoop 4. As shown in FIG. 8, the appropriate angle here means that the central plate portion 26 hits the outer peripheral end of the rim portion 4 a of the hoop 4 (press hoop 4 x) after the mounting of the locking device 20 is completed, and the corner head This is an angle at which 8a can be prevented from rotating in the loosening direction (counterclockwise).

  Next, as shown in FIG. 6, the support plate portion 25 is picked and the central plate portion 26 is twisted rightward. Thereby, the cut | interruption 24 spreads, the support plate part 25 is expand | deployed by J shape, and the planar slow stop 20 is three-dimensionalized. Thereafter, as shown in FIG. 7, the central plate portion 26 and the support plate portion 25 are further twisted, and the portion of the support hole 23 of the developed support plate portion 25 is bound to the shaft portion 8 b of the lug bolt 8 from the back side. The Then, the entangled portions of the support holes 23 are pressed against the shaft portion 8b of the lug bolt 8 by the restoring force of torsion, and the plate thickness portion 26a inside the curved central plate portion 26 is formed into the hoop 4. The rim portion 4a is in contact with the outer peripheral end. At this time, as shown in FIG. 8, the claw plate portion 28 is inserted into the bolt insertion hole 28 of the rim portion 4 a, and is applied to the shaft portion 8 b of the lug bolt 8 by the torsional restoring force of the center plate portion 26 and the support plate portion 25. Pressed. Note that the hole diameter of the bolt insertion hole 28 varies depending on the drum manufacturer. When the hole diameter is small, the claw plate portion 28 is not inserted into the bolt insertion hole 28.

(Action / Effect)
According to the locking device 20 according to the first embodiment, as shown in FIG. 4, the main body plate portion 22, the central plate portion 26, the support plate portion 25, and the claw plate portion 28 are made of a resin having flexibility. Since it is integrally formed from a plate material, it has an extremely simple structure and can be manufactured at a low cost by punching a resin plate or the like.

  As shown in FIG. 5, the center plate portion 26 and the support plate portion 25, as shown in FIGS. 6 to 8, with the rotation stop 21 of the main body plate portion 22 being pushed into the corner head 8 a of the lug bolt 8. By twisting at least one of them, the cut 24 of the support hole 23 is expanded and the support plate portion 25 is developed in a J-shape, and the portion of the support hole 23 of the developed support plate portion 25 becomes the shaft portion 8b of the lug bolt 8. Since it is entangled, the lug bolt 8 can be mounted without removing it from the lug nut 6.

  As shown in FIG. 5, the outer end 24a of the cut 24 is located between the rotation stop hole 21 and the support hole 23. As shown in FIGS. 6 to 8, the resin center plate 26 and the support are provided. Since the torsional restoring force (repulsive force) generated by twisting at least one of the plate portions 25, the portion of the support hole 23 developed in a J shape from the cut 24 is pressed against the shaft portion 8b of the lug bolt 8. The mounting posture of the locking device 20 is stabilized, and the situation where the shaft portion b of the lug bolt 8 is removed from the cut 24 due to vibration generated during performance can be prevented.

  As shown in FIGS. 7 and 8, the rotation hole 21 of the resin-made main body plate portion 22 is pushed into the corner head portion 8a of the lug bolt 8 so as not to rotate relative to the support plate, and is expanded from the cut 24 into a J shape. Since the central plate portion 26 is brought into contact with the outer peripheral end of the rim portion 4a of the hoop 4 in a state where the portion of the support hole 23 of the portion 25 is entangled with the shaft portion 8b of the lug bolt 8, the corner portion of the lug bolt 8 The rotation of 8a in the loosening direction (counterclockwise) can be suppressed, and the lug bolt 8 can be prevented from loosening. Thereby, the fall of tuning of the drum head 3 can be prevented.

  As shown in FIGS. 7 and 8, at least one of the center plate portion 26 and the support plate portion 25 is twisted, so that the planar locking device (part) 20 shown in FIG. 4 is three-dimensionalized and three-dimensionalized. The plate thickness portion 26a of the central plate portion 26 is brought into contact (point contact) with the rim portion 4a of the hoop 4 and the plate thickness portion of the support hole 23 of the support plate portion 25 is brought into contact with the shaft portion 8b of the lug bolt 8. . Therefore, the contact area of the locking device 20 with the hoop 4 can be made as small as possible, and the acoustic performance of the drum 1 can be improved due to the fact that the material of the locking device 20 is a resin harder than rubber. The influence of can be suppressed.

  As shown in FIG. 8, the claw plate portion 28 is pressed against the shaft portion 8 b of the lug bolt 8 by a torsional restoring force (repulsive force) generated by twisting at least one of the central plate portion 26 and the support plate portion 25. It is done. The claw plate portion 28 further stabilizes the mounting posture of the locking device 20 and can accurately prevent the locking device 20 from falling off due to vibration generated by hitting the drum head 3 with a stick during performance.

  In short, according to the locking device 20 of the drum head 3 according to the first embodiment, the lug bolt 8 can be prevented from loosening with a simple structure and at low cost, and can be mounted without removing the lug bolt 8, and the lug bolt 8 and the hoop 4 can be mounted. The contact area with (press hoop 4x) is small, and the influence on the acoustic performance can be suppressed.

(Second Embodiment: Drum Head 3 Loosening Stopper 30)
A “drum head loosening stop” 30 according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 13. The locking device 30 is used for the die-cast hoop 4y (lower hoop in FIG. 3). The die stop hoop (second embodiment) 30 for the die cast hoop 4y shown in FIG. 9 is more die-cast than the above-described loose stop tool (first embodiment) 20 for the press hoop 4x shown in FIG. Based on the difference in shape between 4y and the press hoop 4x, the shape, twist direction, etc. of each component differ, but it is basically composed of similar elements.

  As shown in FIG. 9, the locking device 30 according to the second embodiment includes a main body plate portion 22 having a stop hole 21 to be pushed into the corner head portion 8 a of the lug bolt 8, and a support in contact with the shaft portion 8 b of the lug bolt 8. A support plate portion 25 having a slit (slit) 24 that communicates the inside and outside of the hole 23 and the support hole 23, and a central plate portion 26 that connects the support plate portion 25 and the main body plate portion 22. The center plate portion 26 and the support plate portion 25 are integrally formed from a plate material made of a flexible resin (for example, polyethylene, polyvinyl chloride, polypropylene, etc.). The width of the slit (slit) 24 may be about 1 mm.

  A mark (arrow) 27 for indicating the mounting angle of the main body plate portion 22 with respect to the hoop 4 (die-cast hoop 4y) when the rotation stop 21 is pushed into the corner head portion 8a of the lug bolt 8 on the main body plate portion 22, It is provided along the radial direction of the rotation stop hole 21. The outer end 24a of the cut 24 is located in a region between the rotation hole 21 and the support hole 23, and at least one of the center plate portion 26 and the support plate portion 25 is twisted to widen the cut 24. When this occurs, the support plate portion 25 is developed in a J-shape. The above-mentioned region where the outer end 24a of the cut 24 is located is a line connecting the center of the rotation hole 21 and the center of the support hole 23, and a line passing through the center of the rotation hole 21 perpendicular to the line A. B, where C is a line orthogonal to the line A and passing through the center of the support hole 23, it is an area between the line B and the line C.

  The cut 24 is formed in a curved shape so as to be smoothly connected to the inner peripheral surface of the support hole 23. When the cut 24 is widened by twisting at least one of the central plate portion 26 and the support plate portion 25, the cut 24 is cut. The portion developed along 24 is brought into contact with the outer peripheral end of the rim portion 4a of the hoop 4 by the restoring force of the torsion (see FIGS. 11 to 13). The support plate portion 25 is integrally provided with a claw plate portion 28 formed so as to protrude on the same plane. The claw plate portion 28 is pressed against the shaft portion 8b of the lug bolt 8 by a torsional restoring force generated by twisting at least one of the central plate portion 26 and the support plate portion 25.

  The inner diameter of the stop hole 21 shown in FIG. 9 is determined according to the size of the corner head 8a of the lug bolt 8, but is 5.5 mm in this embodiment. The support hole 23 is substantially elliptical when the cut 24 is widened and the support plate portion 25 is developed in a J shape, so that the support hole 23 is substantially elliptical and has a short diameter. The major axis is 5.5 mm and the major axis is 7 mm. Other dimensions are equivalent to the dimensions of the first embodiment. These numerical values are illustrative and are not limited.

(Installed)
The loose stop 30 according to the second embodiment shown in FIG. 9 is attached to the lower hoop 4 (die-cast hoop 4y) shown in FIG. 3 as described below. First, as shown in FIG. 10, the rotation stop hole 21 of the resin main body plate portion 22 is pushed into the corner head 8 a of the lug bolt 8 so as not to be relatively rotatable. At this time, the mounting angle of the main body plate portion 22 with respect to the hoop 4 is set to an appropriate angle by directing the mark (arrow) 27 of the main body plate portion 22 toward the center of the hoop 4. As shown in FIG. 13, the appropriate angle here means that the center plate portion 26 hits the outer peripheral portion of the rim portion 4 a of the hoop 4 (die-cast hoop 4 y) after the attachment of the locking device 30 is completed, This is an angle at which the portion 8a can be prevented from rotating in the loosening direction (counterclockwise).

  Next, as shown in FIG. 11, the support plate portion 25 is picked and the center plate portion 26 is twisted outward. Thereby, the cut | interruption 24 spreads, the support plate part 25 is expand | deployed by J shape, and the planar slow stop 30 is three-dimensionalized. Then, as shown in FIG. 12, the central plate portion 26 and the support plate portion 25 are further twisted, and the portion of the support hole 23 of the developed support plate portion 25 is moved to the axis of the lug bolt 8 as shown in FIG. The part 8b is bound from the left side. Then, the entangled portion of the support hole 23 is pressed against the shaft portion 8b of the lug bolt 8 by the restoring force of torsion, and the portion of the central plate portion 26 is brought into contact with the outer peripheral portion of the rim portion 4a of the hoop 4. At this time, the claw plate portion 28 is inserted into the inner surface of the rim portion 4a of the hoop 4 (die-cast hoop 4y), and is applied to the shaft portion 8b of the lug bolt 8 by the torsional restoring force of the center plate portion 26 and the support plate portion 25. Pressed.

(Action / Effect)
The action and effect of the locking device 30 according to the second embodiment is basically the same as that of the locking device 20 of the first embodiment, as will be described below. First, as shown in FIG. 9, the main body plate portion 22, the central plate portion 26, the support plate portion 25, and the claw plate portion 28 are integrally formed from a flexible resin plate material. It has a simple structure and can be manufactured at low cost by punching a resin plate.

  As shown in FIG. 10, the center plate portion 26 and the support plate portion 25, as shown in FIGS. 11 to 13, in a state where the rotation stop hole 21 of the main body plate portion 22 is pushed into the corner head 8 a of the lug bolt 8. By twisting at least one of them, the cut 24 of the support hole 23 is expanded and the support plate portion 25 is developed in a J-shape, and the portion of the support hole 23 of the developed support plate portion 25 becomes the shaft portion 8b of the lug bolt 8. Since it is entangled, the lug bolt 8 can be mounted without removing it from the lug nut 6.

  As shown in FIG. 10, the outer end 24a of the cut 24 is located between the rotation stop hole 21 and the support hole 23. As shown in FIG. 11 to FIG. Since the torsional restoring force (repulsive force) generated by twisting at least one of the plate portions 25, the portion of the support hole 23 developed in a J shape from the cut 24 is pressed against the shaft portion 8b of the lug bolt 8. The mounting posture of the looseness stop 30 is stabilized, and the situation where the shaft portion 8b of the lug bolt 8 is detached from the cut 24 due to vibration generated during performance can be prevented.

  As shown in FIG. 13, the rotation stop 21 of the resin-made main body plate portion 22 is pushed into the corner head portion 8 a of the lug bolt 8 so as not to be relatively rotatable, and the support plate portion 25 developed in a J shape from the cut 24. Since the central plate portion 26 is brought into contact with the outer peripheral end of the rim portion 4a of the hoop 4 in a state where the portion of the support hole 23 is entangled with the shaft portion 8b of the lug bolt 8, the corner head portion 8a of the lug bolt 8 is loosened. Rotation in the direction (counterclockwise) is suppressed, and loosening of the lug bolt 8 can be prevented. Thereby, the fall of tuning of the drum head 3 can be prevented.

  As shown in FIGS. 11 to 13, at least one of the center plate portion 26 and the support plate portion 25 is twisted, so that the planar locking device (part) 30 shown in FIG. 9 is three-dimensionalized and three-dimensionalized. The central plate portion 26 is brought into contact (point contact) with the rim portion 4a of the hoop 4 (die-cast hoop 4y), and the plate thickness portion of the support hole 23 of the support plate portion 25 is brought into contact with the shaft portion 8b of the lug bolt 8. The Therefore, the contact area of the locking device 30 with respect to the hoop 4 can be made as small as possible, and the acoustic performance of the drum 1 can be improved due to the fact that the material of the locking device 30 is a resin harder than rubber. The influence of can be suppressed.

  As shown in FIGS. 11 to 13, the claw plate portion 28 has a shaft portion of the lug bolt 8 due to a torsional restoring force (repulsive force) generated by twisting at least one of the center plate portion 26 and the support plate portion 25. 8b. The nail plate portion 28 further stabilizes the mounting posture of the locking device 30 and can accurately prevent the locking device 30 from falling off due to vibration generated when the drum head 3 is hit with a stick during performance.

  In short, according to the loosening stop 30 of the drum head 3 according to the second embodiment, the lug bolt 8 can be prevented from loosening with a simple structure and at low cost, and can be attached without removing the lug bolt 8, and the lug bolt 8 and the hoop 4 can be attached. The contact area with (die-cast hoop 4y) is small, and the influence on the acoustic performance can be suppressed.

  The present invention can be used for the loosening fasteners 20 and 30 of the drum head 3 for suppressing loosening of the drum head 3 mounted as a vibration film in the opening of the cylindrical drum shell 2.

DESCRIPTION OF SYMBOLS 1 Drum 2 Drum shell 3 Drum head 3a Head frame 4 Hoop 4a Rim part 4x Press hoop 4y Die-cast hoop 6 Lug nut 7 Bolt insertion hole 8 Lug bolt 8a Square head 8b Shaft part 20 Stopper 21 Stop hole 22 Main body plate part 23 Support hole 24 Cut 24a Outer end 25 of cut 25 Support plate 26 Central plate 27 Mark 28 Claw plate 30 Loose stop

Claims (3)

A cylindrical drum shell, a drum head that covers the opening of the drum shell, an annular hoop that holds the drum head on the drum shell, a bolt insertion hole formed in the hoop, and a side of the drum shell A lug nut supported by a portion, a lug bolt that is inserted into the bolt insertion hole and screwed into the lug nut to press the drum head against the opening of the drum shell via the hoop, and a head of the lug bolt A drum head locking device for a drum having a formed angular head,
A main body plate portion having a rotation hole to be pushed into a corner head of the lug bolt, a support hole in contact with the shaft portion of the lug bolt, a support plate portion having a notch communicating between the inside and outside of the support hole, the support plate portion, A central plate connecting the main plate and the main plate, the central plate, and the support plate are integrally formed from a flexible resin plate, An end is located between the rotation hole and the support hole,
In the state where the rotation stop hole of the main body plate portion is pushed into the corner head of the lug bolt so as not to be relatively rotatable, at least one of the central plate portion and the support plate portion is twisted to widen the cut and to support the support plate. The plate part is developed in a J-shape, the part of the support hole of the developed support plate part is entangled with the shaft part of the lug bolt, and the part of the entangled support hole is Pressed against the shaft, the central plate abuts against the hoop,
Drum head loosening stop characterized by the above.   A claw plate portion formed so as to protrude on the same plane is integrally provided on the support plate portion, and the claw plate portion is formed by twisting at least one of the central plate portion and the support plate portion. The drum head locking device according to claim 1, wherein the drum head is pressed against a shaft portion of the lug bolt by a restoring force of the generated torsion.   The main body plate portion is provided with a mark indicating an appropriate mounting angle of the main body plate portion with respect to the hoop when the rotation hole of the main body plate portion is pushed into the corner head of the lug bolt. 3. Drum head loosening device according to 1 or 2 below.

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