DART

Description

TECHNICAL FIELD

The present invention relates to a dart that is used as a sport plaything for competing for scores by throwing the dart to a target (dartboard) set wall, or the like.

BACKGROUND ART

Dart competitions have widely developed, and professional competitions are also held as sport competitions for competing for scores. Specifically, in dart competitions, players throw darts (arrow, dart) to a target to compete for high scores set at the center portion of the target, and the players compete for how many darts they can throw to the center portion of the target. Therefore, the dart competitions require that as many darts as possible be stuck concentratedly in the center of the target.

Conventionally, darts disclosed in Patent Literatures 1 to 3 have been known, for example. However, when such darts are thrown, the next dart is thrown consecutively, with the previously-thrown dart being stuck in the target. Therefore, there is a case where the subsequently-thrown dart collides with the dart already stuck in the target, to be flicked out, and the subsequently-thrown dart does not stick in the same position as that of the previously-thrown dart. In addition, the dart already stuck in the target is sometimes flicked out to fall off from the target.

In view of the above, the inventors of the present invention have proposed the dart disclosed in the Patent Literature 4.

CITATION LIST

Patent Literatures

• • Patent Literature 1: Japanese Patent Application Laid-Open Publication No. 2011-110413
  • Patent Literature 2: Japanese Patent No. 5432785
  • Patent Literature 3: Japanese Utility Model Registration No. 3160281
  • Patent Literature 4: Japanese Patent No. 5748345

SUMMARY OF INVENTION

Technical Problem

The proposed dart can restrain a subsequently-thrown dart from colliding with and being flicked out by a dart stuck in a target, and also can restrain the dart stuck in the target from being flicked out by the subsequently-thrown dart, compared with conventional darts. However, there is a desire for further improvements.

The present invention has been made in view of the above-described circumstance, and an object of the present invention is to provide a dart capable of restraining and even preventing a subsequently-thrown dart from colliding with and being flicked out by a dart stuck in a target, and restraining and even preventing the dart stuck in the target from being flicked out by the subsequently-thrown dart more surely than the conventional darts.

Solution to Problem

A dart according to the present invention, which meets the above-described object, includes, in sequence from a distal side to a proximal side of the dart, a tip, a barrel, and a shaft.

The shaft has a diameter which gradually decreases from a distal side toward a proximal side of the shaft, three flights are attached and fixed to the proximal side of the shaft at equiangular positions around a center axis of the shaft, and proximal sides of the flights protrude from the shaft to be connected to one another.

The shaft includes grooves, each of which is formed between the flights adjacent to each other in a circumferential direction of the shaft. Each of the grooves has an inner width which gradually increases from a side of the flights toward an axial direction center part of the shaft, and which gradually decreases from the axial direction center part of the shaft toward a side of the barrel.

Thus, the number of the flights is three, and the flights are attached and fixed to the shaft at the equiangular positions (positions at 120 degree intervals) around the center axis of the shaft, to thereby be capable of making a spacing between the flights adjacent to each other in the circumferential direction of the shaft greater than a spacing of the flights in a case where the number of flights is four (provided at the positions at 90 degree intervals). With such a configuration, when darts are thrown consecutively, a subsequently-thrown dart is less likely to collide with flights of a dart already stuck in the target.

In addition, the shaft is formed in a shape having the diameter which gradually decreases from the distal side toward the proximal side thereof, and the proximal sides of the flights protrude from the shaft to be connected to one another. With such a configuration, the subsequently-thrown dart is less likely to collide with the shaft of the dart already stuck in the target, and even in the case where the subsequently-thrown dart collides with the shaft of the dart already stuck in the target, the subsequently-thrown dart can smoothly pass through.

Furthermore, the shaft includes the grooves, each of which is formed between the flights adjacent to each other in the circumferential direction of the shaft. However, the number of the flights is three, to thereby be capable of making a cross section of each of the grooves (an area of each of the grooves on a surface orthogonal to the axial direction of the shaft) greater than that in the configuration in which the number of the flights is four. Therefore, the above-described working and effect can be further enhanced. Note that the inner width of each of the grooves gradually increases from the side of the flights and then gradually decreases toward the side of the barrel in the axial direction of the shaft. Such a configuration does not impair the strength of the shaft, and even if the distal end of the tip of the subsequently-thrown dart collides with the dart already stuck in the target, the subsequently-thrown dart can smoothly pass through.

It is preferable that the depth of each of the grooves gradually becomes deeper from the side of the flights toward the axial direction center part of the shaft, and gradually becomes shallower from the axial direction center part of the shaft toward the side of the barrel.

In addition, it is preferable that the three grooves have the same shape, and formed at the equiangular positions around the center axis of the shaft.

Furthermore, the shaft is configured to be attachable to and detachable from the barrel.

Advantageous Effects of Invention

A dart according to the present invention is configured such that, when a plurality of darts are thrown consecutively, for example, a subsequently-thrown dart is less likely to collide with flights of a dart stuck in a target, and even in a case where a distal end of a tip of the subsequently-thrown dart collides with the dart stuck in the target, the subsequently-thrown dart can smoothly pass through.

Therefore, compared with conventional darts, the present invention enables the subsequently-thrown dart to stick in the target at a position near the dart stuck in target, without being greatly flicked out by the dart stuck in the target, or the present invention is capable of restraining and even preventing the dart stuck in the target from being flicked out by the subsequently-thrown dart and falling off from the target more surely than the conventional ones. As a result, the present invention enables high scores to be obtained in competitions and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a dart according to one embodiment of the present invention.

FIG. 2 is a front view of a shaft and flights of the dart.

FIG. 3 is a bottom view of the shaft and the flights.

FIG. 4 is a right side view of the shaft and the flights.

FIG. 5 is a cross-sectional view taken along the line A-A in FIG. 2.

DESCRIPTION OF EMBODIMENTS

Next, with reference to the accompanying drawings, descriptions will be made on an embodiment which embodies the present invention, for a better understanding of the present invention.

As shown in FIGS. 1 to 4, a dart 10 according to the one embodiment of the present invention includes, in sequence from a distal side (front side) to a proximal side (back side) thereof, a tip (also referred to as a point) 11, a barrel 12, and a shaft 13, and on the proximal side of the shaft 13, flights 14 are attached and fixed. The dart 10 is configured to, when a plurality of darts 10 are thrown consecutively, be capable of restraining and even preventing a subsequently-thrown dart 10 from colliding with and being flicked out by a dart 10 which was previously thrown and has already stuck in a target (mark: not shown), as well as restraining and even preventing the dart 10 stuck in the target from being flicked out by the subsequently-thrown dart 10, compared with the conventional darts.

Hereinafter, detailed description will be made.

As shown in FIG. 1, the tip 11 is provided at a distal portion of the dart 10 in an axial direction thereof, and is a part that sticks in the target.

The tip 11 is made of metal or plastic, for example, and may be attachable to and detachable from (replaceable with respect to) the barrel 12, with a screw portion or the like (not shown).

As shown in FIG. 1, the barrel 12 is provided at a center portion of the dart 10 in the axial direction thereof. When the dart 10 is thrown, the barrel 12 is generally held.

The barrel 12 is mainly made of metal. The barrel 12 has a weight and is effective for throwing the dart 10 far. Although examples of the material of the barrel 12 include various materials such as brass, nickel alloy, tungsten alloy, and the like, the barrel made of tungsten alloy having a high specific gravity or nickel alloy can be made thinner and hardly causes interference when hitting the target.

Note that the barrel 12 varies in shape, non-slip indentations, weight, and the like.

As shown in FIGS. 1 to 5, the shaft 13 is provided at the proximal portion of the dart 10 in the axial direction thereof. The flights 14 are attached and fixed to the proximal side of the shaft 13, which are the parts exhibiting an effect for enabling the dart 10 to fly straight. In other words, the flights 14 are the parts serving as wings.

The shaft 13 has a circular cross section, and the diameter of the shaft gradually decreases from the distal side toward the proximal side in the axial direction thereof (formed in a tapered shape). The shaft 13 can be attached and fixed to (replaceable with respect to) the barrel 12 by being screwed into the proximal end portion of the barrel 12 with a screw portion (male screw) 15 provided at the distal end portion of the shaft 13. Note that the maximum diameter D (diameter of the distal end excluding the screw portion 15) of the shaft 13 is approximately 4.5 mm to 6.5 mm, for example, and the length L1 (length excluding the screw portion 15) of the shaft 13 in the axial direction is approximately 45 mm to 60 mm, for example. However, the maximum diameter and the length of the shaft 13 are not specifically limited to the above-described values.

Various materials, for example, metal, resin (plastic), polycarbonate, carbon composite, or the like can be used for the shaft 13. Although the material of the shaft 13 is not specifically limited as long as the above-described effect can be achieved, it is preferable to use polyamide-based resin as the material. The polyamide-based resin has an amide bond, and composed mainly of an amino acid, a lactam, or a diamine and a dicarboxylic acid, for example.

It is preferable to mold the shaft 13 and the flights 14 integrally (formed as integrated structure) by injection molding using a resin composed of the same material. However, the shaft and the flights can be molded separately and combined. In this case, cuttings are formed on the proximal side of the shaft, and the flights can be attached and fixed to the shaft by being inserted respectively into the cuttings. Note that the shaft and the flights may be made of the same material, or different materials.

On the proximal side of the shaft 13, three flights 14 are attached and fixed (formed) at the equiangular positions around the center axis of the shaft 13. In the present embodiment, the equiangular positions are the positions at 120 degree intervals around the center axis of the shaft 13. However, even if the positions shift within a range of approximately plus or minus 1 degree (range of 119 degrees to 121 degrees), for example, due to manufacturing errors or the like, such positions are also included in the equiangular positions.

The distal sides of the flights 14 are attached and fixed to the outer circumference of the shaft 13, so as to be located from the axial direction center part to the proximal side of the shaft 13. The proximal sides of the flights 14 protrude from the shaft 13 to the outside (rear side) of the proximal side of the shaft 13 in the axial direction and are connected to one another. Therefore, as shown in FIG. 4, when the dart 10 is viewed from the rear side thereof, the three flights 14 are arranged radially around the center axis of the dart 10.

Note that the attaching length of each of the flights 14 to the shaft 13 is, for example, approximately 50% or more and 80% or less (preferably, 60% or more) of the length L2 of each of the flights 14 along the axial direction of the shaft 13, the height H of each of the flights 14 with respect to the center axis of the shaft 13 is approximately 15 mm to 25 mm, and the length L3 of a part of the shaft 13 in the axial direction, the part not including the flights 14, is approximately 20 mm to 30 mm, but these are not specifically limited.

The three flights 14 have the same shape, and can be formed in a shape, for example, standard, shape (harrows shape), kite, teardrop, slim, or the like. As shown in FIG. 2, the outer peripheral outline of each of the flights 14 is configured by a curved surface including, from the distal side toward the proximal side, a distal side slope 16 and a proximal side slope 17 that are continuously formed in the axial direction of the shaft 13. The distal side slope 16 has a gentle sloping angle. The proximal side slope 17 has a sloping angle steeper than that of the distal side slope 16. Specifically, a radius of curvature R1 of a rising portion that constitutes the distal side slope 16 is approximately 8 mm to 13 mm. The proximal side slope 17 rises at approximately 58 degrees to 65 degrees with respect to the center axis. Radii of curvature R2, R3, and R4 from the distal side slope 16 to the proximal side slope 17 are set respectively as follows: R2 is approximately 17 mm to 21 mm; R3 is larger than R2 and is approximately 27 mm to 33 mm; and R4 is smaller than R2 and is approximately 4 mm to 7 mm. However, these radii of curvature are not specifically limited to the above-described values.

In addition, in general, the thickness of each of the flights 14 is approximately 0.3 mm to 0.5 mm, and the length L4 up to the proximal ends the flights 14, which includes the length L1 of the shaft 13, is approximately 65 mm to 75 mm, for example, but the thickness and the length are not specifically limited.

The shaft 13 is provided with grooves 18 (three in total), each of which is formed between the flight 14 and the flight 14 that are adjacent to each other in the circumferential direction of the shaft 13. The respective grooves 18 are formed at the equiangular positions around the center axis of the shaft 13. In the present embodiment, the equiangular positions are the positions at 120 degree intervals around the center axis of the shaft 13. However, even if the positions shift within a range of approximately plus or minus 1 degree (range of 119 degrees to 121 degrees), for example, due to manufacturing errors or the like, such positions are also included in the equiangular positions.

The shape, the inner width, and the depth of each of the grooves 18 are set such that the strength of the shaft 13 is not impaired and the subsequently-thrown dart 10 can smoothly pass through, even if the subsequently-thrown dart 10 collides with the dart 10 stuck in the target.

The three grooves 18 have the same shape. The inner width of each of the grooves gradually increases (inverted tapered shape) from the side of the flights 14 (position where the three flights are connected to one another) toward the axial direction center part of the shaft 13, and gradually decreases (tapered shape) from the axial direction center part of the shaft 13 toward the side of the barrel 12 (in the area where the flights 14 do not exist in the axial direction of the shaft 13). Furthermore, the depth of each of the grooves 18 gradually becomes deeper from the side of the flights 14 toward the axial direction center part of the shaft 13, and gradually becomes shallower from the axial direction center part of the shaft 13 toward the side of the barrel 12 (in the area where the flights 14 do not exist in the axial direction of the shaft 13).

A barrel 12-side end portion and a flight 14-side end portion of each of the grooves 18 are each formed in an acute angle shape (V-shape). Each of the grooves 18 has the maximum inner width at the position which is the axial direction center part of the shaft 13 and which is closer to the side of the barrel 12 (in the area where the flights 14 do not exist in the axial direction of the shaft 13). Therefore, the flight 14-side end portion of each of the grooves 18 is pointed sharper (having a more acute shape) than the barrel 12-side end portion of each of the grooves 18. Note that the maximum inner width of each of the grooves 18 is approximately 3 mm to 5 mm, for example, but not specifically limited thereto.

In addition, the bottom surface of each of the grooves 18 has an arc-shaped cross section (curve: the radius of curvature is approximately 0.4 mm to 0.6 mm, for example), as shown in FIG. 4 and FIG. 5. Each of the grooves 18 has the maximum depth at the position which is the axial direction center part of the shaft 13 and which is closer to the side of the barrel 12 (in the area where the flights 14 do not exist in the axial direction of the shaft 13).

Note that the position where the inner width of each of the grooves 18 is the maximum and the position where the depth of each of the grooves 18 is the maximum are the same position, but may be different positions.

As described above, the dart 10 is configured such that the number of the flights 14 is three, the shaft 13 has the shape having the diameter gradually decreasing from the distal side toward the proximal side thereof, and further, each of the grooves 18 having the above-described configuration is formed between the flight 14 and the flight 14 that are adjacent to each other in the circumferential direction of the shaft 13. With such a configuration, when a plurality of darts 10 are thrown consecutively, the distal end of the tip 11 of the subsequently-thrown dart 10 is prevented from colliding with the proximal end of the shaft 13 of the dart 10 stuck in the target, to thereby prevent the subsequently-thrown dart 10 from being flicked out. As a result, the subsequently-thrown dart 10 sticks near the dart 10 stuck in the target. In addition, such a configuration is capable of restraining and even preventing the dart 10 stuck in the target from being flicked out by the subsequently-thrown dart 10, compared with the conventional darts.

The present invention has been described above with reference to one embodiment, but the present invention is not limited to the configuration described in the configuration of the above-described embodiment. The present invention includes another embodiment and a modification that can be considered within a range of the subject matters recited in claims. For example, even in a case where the dart of the present invention is configured by combining a part or all of the respective actual examples described above and a modification, the dart is included in the scope of claims of the present invention.

In the above-described embodiment, description has been made on the case where the shaft is attachable to and detachable from the proximal end portion of the barrel with the screw portion provided at the distal end portion of the shaft. However, the shaft may be configured so as not to be detachable from the barrel.

INDUSTRIAL APPLICABILITY

According to the dart of the present invention, when a plurality of darts are thrown consecutively, the subsequently-thrown dart is restrained and even prevented from colliding with and being flicked out by the dart stuck in the target and the dart stuck in the target is restrained and even prevented from being flicked out by the subsequently-thrown dart, compared with the conventional darts. As a result, the dart of the present invention enables high scores to be obtained in competitions and the like. Therefore, the present invention has an industrial applicability in that it can contribute to improving the manufacturing and sales of darts, for example.

REFERENCE SIGNS LIST

• • 10: dart, 11: tip, 12: barrel, 13: shaft, 14: flight, 15: screw portion, 16: distal side slope, 17: proximal side slope, 18: groove