The present invention relates to a drum with a head adjusting device.
Drums such as bass drums and snare drums include head adjusting devices located around its body for adjusting the tension of a drumhead (for example, Japanese Laid-Open Patent Publication No. 05-307383).
As shown in
A head adjusting device 23 for adjusting the tension of the upper head 3 includes a lug 7, which is secured to the periphery of the body 2, a lug nut 8, which is located at the upper end of the lug 7, and a lug bolt 9, which couples the lug nut 8 to the upper hoop 6. The lug bolt 9 is inserted through the upper hoop 6 from above the drum 22 and is threaded into the lug nut 8 at its distal end. When adjusting the tension of the upper head 3, the lug bolt 9 is selectively tightened or loosened with respect to the lug nut 8 so that the upper head frame 5 is shifted along the axial direction via the upper hoop 6.
When playing the drum 22, the lug bolt 9 might be loosened by strong vibration of the upper head 3, and the drum 22 might go out of tune. Therefore, several structures have been proposed to prevent undesirable loosening of the lug bolt 9. For example, a head adjusting device 23 has been proposed that has a thin rubber sheet 11 below the lug nut 8. An oval hole 12 is formed in the rubber sheet 11 to permit the distal end of the lug bolt 9 to be inserted therethrough (see
However, since the rubber sheet 11 has high elasticity and flexibility, although the rubber sheet 11 is press-fitted to the root of the threaded portion 9b of the lug bolt 9, the vibration of the upper head 3 might not be suppressed sufficiently. Furthermore, when continuously playing the drum 22 for a long period, there is a high possibility that the lug bolt 9 will be gradually loosened regardless of the player's intention.
Another structure (not shown) for preventing loosening of the lug bolt 9 has been proposed that uses an annular member made of nylon instead of the rubber sheet 11. A bore, which has a slightly smaller diameter than the outer diameter of the lug bolt 9, is formed in the annular member. Since the lug bolt 9 is threaded into the bore, great frictional force is generated between the annular member and the threaded portion 9b of the lug bolt 9. As a result, the lug bolt 9 is prevented from undesirably rotating by shocks and vibration. On this point, the structure prevents the lug bolt 9 from being loosened even if the drum 22 is played for a long time, more reliably than the case where the rubber sheet 11 is provided. However, in this case, the torque required for tightening the lug bolt 9 is increased and a special tuning key must be used. As a result, the tuning process becomes troublesome. Also, the annular member will deform after a long period of usage and the frictional force will be reduced. This might gradually cause undesirable loosening between the annular member and the lug bolt 9.
As other structure for preventing undesirable loosening, a structure in which another lock nut is provided on the lug bolt 9 above the lug nut 8 to doubly couple the lug nut 8 and a structure in which a thin plate-like member made of plastic is provided between the head of the lug bolt 9 and the upper hoop 6 to prevent unintentional rotation have been proposed. However, in these cases, the lock nut must be loosened or the thin plate-like member must be removed every time the drum 22 is tuned. Therefore, the tuning process is complicated.
Accordingly, it is an objective of the present invention to provide a drum that facilitates a tuning process and easily prevents undesirable loosening of a coupling bolt caused by vibration during a performance.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, a drum including a cylindrical body, a head, a cylindrical head frame, a hoop, a plurality of fasteners, a plurality of coupling bots, and a plurality of loosening prevention structures is provided. The cylindrical body has an opening, an outer circumference, and axial direction. The head covers the opening of the body. The head includes a rim and an outer circumference. The cylindrical head frame is fitted to the outer circumference of the body. The head frame retains the rim of the head and is movable along the axial direction of the body. The hoop is provided at the outer circumference of the head. The hoop abuts against the head frame to press the head frame along the axial direction of the body so that tension is applied to the head. The hoop includes a plurality of mounting holes. The fasteners are located at the outer circumference of the body. Each fastener is located opposite to the hoop with the head frame located in between, and each fastener includes a nut. The coupling bolts extend along the axial direction of the body. Each coupling bolt includes a head, with the head located opposite to the nut of one of the fasteners with the hoop located in between. Each coupling bolt is inserted in one of the mounting holes and threaded to said nut so that the hoop is coupled to the fastener. Each loosening prevention structure is located between the head of one of the coupling bolts and the hoop, and includes an annular elastic body through which said one of the coupling bolts is inserted and a deformation restricting member, which restricts deformation of the elastic body along said axial direction.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
a) is a partial cross-sectional view illustrating a prior art drum; and
b) is a cross-sectional view of the drum taken along line 6b-6b of
A drum 1 according to one embodiment of the present invention will now be described. Like or the same reference numerals are given to those components that are like or the same as the corresponding components of the prior art shown in
Each head adjusting device 4 for adjusting the tension of the upper head 3 includes a fastener, which is a lug 7 in this embodiment, a lug nut 8, and a lug bolt 9. The lug 7 is secured to the outer circumference of the body 2. The lug nut 8 is located at the upper end of the lug 7. The lug bolt 9 couples the lug nut 8 to the upper hoop 6. The lug 7 is secured to the body 2 with two screws 18 inserted from the inside of the body 2 with one side of the lug 7 in close contact with the outer circumferential surface of the body 2. The lower portion of the lug nut 8 is located inside the lug 7 and the upper end of the lug nut 8 projects upward from the upper surface of the lug 7. A rubber sheet 11 is located below the lug nut 8. The rubber sheet 11 contacts the lower surface of the lug nut 8 and prevents the lug nut 8 from undesirably rotating while screwing the lug bolt 9 into the lug nut 8. An oval hole 12 (see
The lug bolt 9 is inserted into a mounting hole 13 formed in the upper hoop 6 from above the drum 1. A threaded portion 9b is formed at the distal end of the lug bolt 9 for threadably engaging the lug nut 8. The threaded portion 9b is inserted through the lug nut 8 and the hole 12 of the rubber sheet 11. At this time, the rubber sheet 11 is press-fitted to the root of the threaded portion 9b to prevent undesirable rotation of the lug bolt 9.
A loosening prevention structure is located between a head 9a of the lug bolt 9 and the upper hoop 6. The loosening prevention structure is constituted by a washer 16 with rubber inserted between the lower surface of the head 9a, which is for rotating the lug bolt 9, and the upper surface of the upper hoop 6. The washer 16 with rubber includes an annular elastic body 15 made of rubber and a bowl-shaped cover 14, which covers the elastic body 15. As show in
The inner diameter of the insertion hole 14c of the annular portion 14a is slightly greater than the outer diameter of the lug bolt 9. Since the axial thickness of the elastic body 15 is greater than the height of the cylindrical portion 14b, the lower end of the elastic body 15 projects downward from the lower end of the cylindrical portion 14b. With this structure, when the washer 16 with rubber is attached to the lug bolt 9, the elastic body 15 applies inward force to the lug bolt 9 to eliminate elastic deformation so that its shape is restored to the state before being attached to the lug bolt 9. Therefore, the washer 16 with rubber is secured to the lug bolt 9. Therefore, when the lug bolt 9 is detached from the drum 1 when exchanging the upper head 3, the washer 16 with rubber is prevented from falling off the lug bolt 9.
As shown in
In the state shown in
When tuning up the drum 1, the head 9a of the lug bolt 9 is rotated to adjust the length of the lug bolt 9 threaded into the lug nut 8. The tension of the upper head 3 is adjusted accordingly. More specifically, when tuning the upper head 3 to increase the tension, the head 9a of the lug bolt 9 is rotated clockwise C from the state shown in
Prevention of loosening of the lug bolt 9 due to vibration during a performance will now be described in relation to the washer 16 with rubber. Vibration caused during a performance is described below. In
However, since the lug bolt 9 and the washer 16 with rubber move down slightly later than the upper head frame 5 due to inertia, the space S1 between the lower surface of the head 9a of the lug bolt 9 and the upper hoop 6 is instantaneously widened. The space S1 might instantaneously become wider than the space S2 between the lower surface of the head 9a of the lug bolt 9 and the upper hoop 6 in the state shown in
As described above, when the lug bolt 9 moves along the axial direction with respect to the upper hoop 6 by vibration, since the elastic body 15 is compressed along the axial direction by the length corresponding to the space S in advance, the elastic body 15 keeps applying force to the lower surface of the head 9a of the lug bolt 9 and the upper surface of the upper hoop 6. Therefore, since the vibration caused by playing the drum 1 is absorbed by the elastic body 15, a gap is not formed between the lower surface of the head 9a of the lug bolt 9 and the upper surface of the annular portion 14a and between the lower end of the elastic body 15 and the upper surface of the upper hoop 6. Since the lug bolt 9 is prevented from undesirably rotating and loosening of the lug bolt 9 is suppressed, the drum 1 does not go out of tune during a performance. The elastic body 15 according to the preferred embodiment does not deform excessively since the deformation restricting member, which is the cylindrical portion 14b, keeps the length of the elastic body 15 compressed along the axial direction constant (that is, the length corresponding to the space S). As a result, the elastic body 15 can exert constant force for a long period.
Also, the elastic body 15 according to the preferred embodiment has an inner diameter that is slightly smaller than the outer diameter of the lug bolt 9 and is suppressed from being deformed outward by the inner surface of the cylindrical portion 14b. Therefore, the elastic body 15 always tightens the outer circumferential surface of the lug bolt 9. Therefore, strong frictional force acts between the elastic body 15 and the lug bolt 9, and the lug bolt 9 is further prevented from being loosened.
When screwing the lug bolt 9 of the preferred embodiment into the lug nut 8, torque required for rotating the lug bolt 9 is small until the lower end of the elastic body 15 abuts against the upper surface of the upper hoop 6. Therefore, the lug bolt 9 can be rotated by hand without using a special tuning key. The head adjusting devices 4 for adjusting the tension of the lower head each employ the loosening prevention structure that is the same as the head adjusting devices 4 for adjusting the tension of the upper head 3.
The preferred embodiment has the following advantages.
(1) The washer 16 with rubber, which includes the elastic body 15 and the cover 14, is inserted between the head 9a of the lug bolt 9 and the upper hoop 6. The elastic body 15 deforms to absorb vibration caused by playing the drum 1. Therefore, a gap is not formed between the head 9a of the lug bolt 9 and the cover 14 and between the elastic body 15 and the upper hoop 6. This prevents the lug bolt 9 from undesirably rotating and suppresses loosening of the lug bolt 9. As a result, the drum 1 is prevented from going out of tune due to vibration caused during a performance.
(2) The washer 16 with rubber includes the elastic body 15 made of rubber and the cylindrical portion 14b, which covers the outer circumference of the elastic body 15. Therefore, while being prevented from deforming outward by the abutment against the inner surface of the cylindrical portion 14b, the elastic body 15 deforms inward thereby tightening the lug bolt 9. Therefore, strong frictional force acts between the elastic body 15 and the lug bolt 9, and the lug bolt 9 is further prevented from loosening.
(3) The drum 1 includes the deformation restricting member, that is, the cover 14 for maintaining the axial deformation length of the elastic body 15 to be constant. The deformation restricting member forms the space S between the lower end of the cylindrical portion 14b and the upper surface of the upper hoop 6 when the elastic body 15 is not axially deformed. Therefore, when the lug bolt 9 is threaded into the lug nut 8, the elastic body 15 is prevented from being excessively deformed. Thus, the life of the elastic body 15 is easily extended.
(4) Since the inner diameter of the elastic body 15 before being attached to the lug bolt 9 is slightly smaller than the outer diameter of the lug bolt 9, the elastic body 15 applies inward force to the lug bolt 9 when being attached to the lug bolt 9. Therefore, when the lug bolt 9 is detached from the drum 1, the washer 16 with rubber does not fall off the lug bolt 9. Therefore, the possibility of losing the washer 16 with rubber is reduced.
It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.
As shown in
When using the flat washer 17 made of resin, ribs 21 (see
As shown in
When attaching the washer 16 with rubber to the drum 1, the washer 16 with rubber may be arranged such that the annular portion 14a contacts the upper hoop 6. In this case, advantages are provided that are the same as the preferred embodiment described above. The flat washer 17 may be located between the lower surface of the head 9a of the lug bolt 9 and the washer 16 with rubber.
The annular portion 14a of the cover 14 may be omitted. That is, the cover 14 may be formed with only the cylindrical portion 14b. In this case also, corresponding operation and advantages as the deformation restricting member are obtained in the same manner as the preferred embodiment described above.
A predetermined gap may be formed between the inner surface of the cylindrical portion 14b and the outer circumferential surface of the elastic body 15 within a range in which the lug bolt 9 is sufficiently prevented from loosening by vibration caused during a performance.
A spring washer or a conical disk spring may be used instead of the washer 16 with rubber.
The loosening prevention structure (the washer 16 with rubber) of the preferred embodiment may be applied to a head adjusting device that includes a tension pipe. The tension pipe is provided instead of the pair of lugs 7 located along the axial direction of the body 2. That is, the tension pipe is a cylinder having upper and lower openings and extends along the axial direction of the body 2 at a position separate from the outer circumference of the body 2. The upper and lower ends of the tension pipe are provided with a pair of nuts to be threaded on to the threaded portion 9b of the lug bolt 9 located at the upper end of the drum 1 and a threaded portion (not shown) of a lug bolt located at the lower end of the drum 1.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
Number | Date | Country | Kind |
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2004-211724 | Jul 2004 | JP | national |
Number | Name | Date | Kind |
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4875818 | Reinwall | Oct 1989 | A |
5193960 | Fukushima et al. | Mar 1993 | A |
5208412 | Hoshino | May 1993 | A |
6048150 | Clarke | Apr 2000 | A |
6231286 | Bogatz et al. | May 2001 | B1 |
6686527 | Hagiwara | Feb 2004 | B2 |
6828495 | Ishimatsu | Dec 2004 | B2 |
Number | Date | Country |
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05-307383 | Nov 1993 | JP |
Number | Date | Country | |
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20060016319 A1 | Jan 2006 | US |