JP2003279300A - Dimple bb bullet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce polishing time, and to enhance a distance and hit accuracy by determining a shallow water glass-like recess arrangeable even on a BB bullet having a diameter of 6 mm, that is, the number of dimples, an arranging position, and a shape, and improving straightness of a trajectory by increasing a specific gravity, while maintaining sphericity. <P>SOLUTION: A dimple arranging toy BB bullet is characterized in that a large number of dimples are arranged in a position for equalizing surface arranging density in a three-dimensional symmetrical position to the spherical center on a sphere surface. In the dimple BB bullet, the three-dimensional symmetrical and arranging density equal position is a position of the respective apexes of a regular polyhedron inscribed in a sphere, for example, a position of the respective apexes of an inscribed regular icosahedron. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dimple BB bullet.

[Prior art]

The BB bullet is a plastic spherical bullet used for an air gun. It is so called because it has a spherical shape of steel for ball bearings. Air guns include handguns, long guns, and SMGs. Gas pressure and air pressure of CFC gas 134a are used as power sources for firing bullets, and there are a gas blowback system and an air cocking system for operating these power sources. We will not violate the gun sword method, except for those with powers beyond common sense and those that are prohibited from selling. Therefore, I do not have to worry about the amount of commercially available products that I use, and they are widely used in survival games and shooting competitions.

A BB bullet having a spherical steel shape for ball bearings has a smooth spherical surface, and the BB bullet itself is not subjected to any work. HO at the upper part of the barrel of the air gun, near the drug chamber
With the PUP system device attached, a rotational force is applied by the BB bullets coming into contact with the tip of the BB bullets while passing through the barrel, and the BB bullets rotate upward and fly out of the muzzle. However, even if an upward rotation is given, lift is not increased due to spherical smoothness, range is not extended, and accuracy cannot be expected to increase.

On the other hand, the dimples provided on the surface of the golf ball are not ornaments but play an important role in determining the flight distance, and there is no golf ball without dimples. Dimples on a golf ball increase lift and help air wrap around behind the ball,
It is a known fact to prevent the reduction of air pressure behind the ball and reduce the air resistance. The golf ball has a mass of about 46 gr,
The diameter is about 43 mm and the mass-to-volume ratio is about 1.1, while the BB shell has a mass of 0.12 gr to 0.4.
3 gr, diameter about 6 mm, mass ratio about 1. Initial speed is BB
Approximately 70 m / s for a bullet and 3 yards for a 200 yard golf ball
It is estimated that it will have a similar initial velocity from the place where it will fly in about 4 seconds. Therefore, the Reynolds number, which is the ratio of the inertial force of the flying object and the kinematic viscosity coefficient of air that is a fluid, has the same dimension value, and the theory that applies to golf balls should also apply to BB bullets.

However, since the golf ball has the dimensions as described above, it is possible to dispose 400 to 500 dimples, but in the case of a BB bullet having a diameter of 6 mm, there is no room to form such a large number of dimples. , I haven't seen it until now.

[0006]

Therefore, the number and position of dimples that can be arranged on a BB bullet having a diameter of 6 mm,
It is an object of the present invention to provide a BB bullet whose shape is determined, its specific gravity is increased while maintaining the accuracy of a true sphere to improve the straightness of the trajectory, and the flight distance and the accuracy of hit are improved. .

[0007]

In order to achieve this object, the invention according to claim 1 arranges the dimples in a position symmetrical with respect to the center of the sphere on the surface of the sphere and at a position where the surface arrangement density is uniform. It is configured to be.

In order to achieve this object, the invention according to claim 2 is such that the positions of the three-dimensional symmetry and the uniform arrangement density are the positions of the vertices of a regular polyhedron inscribed in the sphere, for example, the positions of the vertices of a regular icosahedron. It is configured such that dimples are provided in the recess.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of the dimple BB bullet (1), and FIG. 2 is a side view of the same. Since the BB bullet has a diameter of 6 mm as described above, the shape and number of the dimples (2) recessed in the BB bullet must be adapted to the shape. FIG. 1 shows a BB bullet in which twelve watch glass-shaped dimples (2) having a diameter of 0.5 mmφ and a depth of 0.2 mm are recessed on a spherical surface having a diameter of 6 mmφ.
In order to position the 12 dimples (2) recessed portions on the spherical surface, it is sufficient to select the contact point with the apex of the regular icosahedron inscribed in the sphere.

In order to set the number of dimples (2) to 20 on the spherical surface, the dimples (2) are recessed at 20 contact points of a regular dodecahedron inscribed in the sphere. The following is a convenient method that approximates this. That is, an arc of a semicircle is drawn with the diameter of the sphere as an axis, three points that divide the arc into four are defined, and 18 points obtained by rotating the arc of the semicircle once every 60 degrees and both ends of the diameter. A total of 20 points may be selected by adding the above two points. Ideally, the position of three-dimensional symmetry and the uniform spherical arrangement is located at the center position of each surface of the regular icosahedron circumscribing the sphere, but the above procedure approximates this. Uneven dimples (2)
If is placed, the balance of rotation will be lost and the linearity of the flight trajectory will deteriorate. In the embodiment in which the number of dimples (2) is 12 as shown in FIGS. 1 and 2, the dimples (2) are arranged at concave positions such that the 12 vertices of the regular icosahedron circumscribing the sphere are three-dimensional. Both conditions are symmetric and the spherical arrangement density is uniform.

As an example of further increasing the number of dimples (2), 12 centers and 15 vertices of each surface of a regular dodecahedron.
A total of 27 dimples (2) can be arranged, and a total of 32 dimples (2) including 20 centers and 12 vertices of each face of the regular icosahedron can be arranged. Next, it is also possible to draw concentric circles at equal intervals around one point on the spherical surface and arrange them on the line. Further, it may be spirally arranged from one point on the spherical surface. In this embodiment, the diameter is 0.
Clock plate-shaped dimples (2) with a depth of 5 mm and a depth of 0.2 mm
However, the dimension can be arbitrarily set according to the number, and the elastic weight can also be arbitrarily set by selecting a filler (hereinafter referred to as filler). A flat surface may be used instead of the dimple (2). As described above, in addition to the method of reproducing the dimple shape on the surface of the BB bullet in the shape of the mold, granular (diameter 0.4 mm to 1 mm or so)
BB of metal or hard material with grinding power at high speed
By uniformly striking the entire surface of the bullet, it is possible to reproduce extremely small dents or concave scratches on the surface of the BB bullet almost uniformly. As an example, B without dimple processing
Use bullet B and use a shot blasting machine for Keisand (1
The particles were struck at a high speed. As a result, a depression having a depth of about 0.01 mm could be reproduced as a whole.

To improve the straightness of the BB bullet, it is effective to increase the sphericity. Ideally, the same dimensions are obtained no matter which part is measured, but there are various restrictions. Since a general BB bullet manufacturing method is injection molding of a resin, even if a precision mold is manufactured, it is affected by shrinkage, and a parting line and a gate remain, so that a polishing step is required. A simple polishing that considers the cost inevitably results in a compromise that leaves an error of about 5/100 mm. If you take the cost out of consideration, you can get the same precision as an industrial bearing, but this requires an expensive manufacturing line, and loses price competitiveness as a toy gun bullet, resulting in a fall. To improve the accuracy within a realistic range, it is necessary to improve the polishing method, add sorting work, or fundamentally improve the manufacturing method. However, these will increase the cost, so it will be about 5/100 mm as a toy bullet. The error is within the compromise range. There are other causes that impair straightness. When the resin is produced alone, the specific gravity required for the product cannot be obtained. Therefore, a filler of particles or fibrous substances having a larger specific gravity than the resin is kneaded to obtain a larger specific gravity than the resin alone.
If the distribution of the filler is uniform, the specific gravity of each part of the bullet becomes equal, the vibration during flight decreases, and the straightness increases. However, in order to uniformly disperse the filler in the resin, it is necessary to devise a kneading work method or increase the number of times and the time, which also leads to an increase in cost. Therefore, the current situation is to make a compromise as a product commensurate with the cost without causing problems.

When a dimensional error occurs in the BB bullet in the diametrical direction or a partial difference in specific gravity occurs, the center of gravity shifts, the bullet vibrates while flying, and the straightness is impaired. Therefore, by providing a dent on the surface, the surface layer volume corresponding to the depth of the dent on the outermost surface decreases, and the weight density approaches the center.Therefore, errors due to sphericity and non-uniformity of the specific gravity of the molding material Is reduced, and deflection during flight is reduced, which improves straightness.

In the production of BB bullets by the injection molding method, a polishing step is required to remove the parting line and the gate, and to increase the accuracy of the true sphere. Only the polishing area is reduced and the polishing time is shortened. To reduce the polishing time, use a coarse-grained media such as a polishing stone or compound with strong grinding power,
The surface becomes rough. Since a glossy finish is preferred as a product, the particles forming the mediar are gradually made finer and the surface of the BB bullet is gradually polished. The finer the particles of the media in the first polishing, the less the number of polishing required for gloss finish. However, media with finer particles have a weaker grinding force than those with coarser particles, and thus require a longer polishing time. As a result of recessing the dimples (2), the polishing time is shortened if the polishing area is reduced, and when polishing is performed in the same time as the conventional one, a finer media can be used as compared with the case without the dimples (2). . As a result, the number of times of polishing required for glossy finish is reduced, which contributes to cost reduction. Since the diameter of the BB bullet is 6 mm and the depth of the dimple (2) is 0.2 mm, the surface area of the sphere without the dimple (2) is about 90 square mm, whereas the surface area of the BB bullet without the dimple is about 113 square mm. As a result, the dimple (2) recess results in a reduction in the polished area of about 20%. The reduction of the polishing area leads to shortening the polishing time.

A mixed raw material of powdery polystyrene resin (hereinafter referred to as PS resin) 30%, calcium carbonate powder and zinc oxide fine powder is melted in an injection molding machine and injected from a nozzle to pass through a sprue, a runner and a gate. It is poured to the molding die. Since the specific gravity of PS resin is 0.95 and that of calcium carbonate is 2.5, the specific gravity of the product is larger than 1. Zinc oxide fine powder is added to improve the flow. The multi-cavity plastic molding die has a large number of cavities, and the number of semi-spherical convex portions for forming dimples increases. In particular, when there is a convex portion for dimple formation on the parting line, careful work is required. After solidifying and releasing, spherical barrel polishing with a barrel machine requires a shorter working time due to the reduction of the polishing area due to the arrangement of dimples.

The polishing time required for BB bullets was compared by the presence or absence of dimples (2). In dry polishing with a rotating barrel, powdered alumina No. 240 was used as the polishing medium. The time taken for the diameter to change from 5.98 mm to 5.95 mm was measured for both dimple bullets and non-dimple bullets that had the same resin composition and specific gravity produced under the same conditions. The ideal diameter for a BB bullet for a toy is 5.95 mm. The measurement was performed 10 times at a rotation speed of 200 rpm. As a result, the dimple-free bullet took 2 hours and 20 minutes, while the dimple-shot took 1 hour and 10 minutes.

At present, many manufacturers manufacture toy bullets as game bullets. Most products are white or milky white for visibility. The shape of the bullet is spherical,
Since the diameter is about 6 mm, there is almost no apparent difference, and it is difficult to distinguish them. Although the packaging is inevitably appealing to consumers, the dimple shell itself is easy to use and can be easily identified, which has the effect of increasing demand.

[0018]

[Table 1]

Table 1 is a result table of elasticity test. A rifle-type air cocking toy gun that urges a piston with a spring to compress air and then fires a bullet with the air pressure is used. A toy gun without a HOPUP mechanism that gives reverse rotation to the bullet is used. The test bullets were compared by using a 6 mm diameter dimple-free bullet manufactured by Company A and a toy bullet with a 6 mm diameter 6 mm diameter and 12 mm deep dimples arranged on 12 sphere surfaces. The weight of each sample is 0.2 gr. The test is conducted indoors, the target is placed at a distance of 5 m from the muzzle, 10 shots each, 10 times in total.
00 shots were fired and the spread of the landing position was observed. The target was to use a plate-like clay, select the two shots that were most offset from the center, and measure the center-to-center distance of the bullet hole depression. When 10 times are averaged, 45.2 mm of the dimple-free bullet is 35.2 mm for the dimple-placed bullet, which clearly improves the elasticity.

[0020]

[Table 2]

[0021]

[Table 3]

Table 2 is a flight distance test result table. Like the above elasticity test, HO with a rifle type air cocking toy gun
A toy gun without a PUP mechanism was used. On the other hand, Table 3
Is a flight distance test result table when a toy gun with a HOPUP mechanism is used. Similar to the above collection test, the test bullets were made by Company A with a diameter of 6 mm and without dimples, and by our company with a diameter of 6 mm, 1
Comparison was made using two-position dimple placement bullets. The weight of each sample is 0.2 gr. Outside, it was leveled with a leveler so that the center of the muzzle was 1.5 m above the ground, and fixed with a vise. A total of 100 shots were tested 10 times each in an environment of a wind speed of 2 m.

According to Table 2, when comparing using a toy gun without a HOPUP mechanism, the average of 10 test results is 41.85 m without dimples, 52.95 m with 12 dimples arranged, Flying distance about 27%
Will increase. Similarly, in the flight distance test using the toy gun with the HOPUP mechanism shown in Table 3, the average of 10 times is 54.9 m without dimples, 62.0 m with 12 dimple placement bullets, and a 13% increase in flight distance. Becomes

[0024]

【The invention's effect】

The dimple arrangement BB according to the invention of claim 1
According to the bullet (1), the polishing time in manufacturing is shortened, the straightness of the flight trajectory can be secured, the elasticity is improved, the flight distance is extended, and the demand can be expected to increase.

The dimple arrangement BB according to the invention of claim 2
According to the bullet (1), the pressure resistance during flight of the bullet is reduced to increase the flight distance, the polishing time is shortened in manufacturing, the straightness of the flight trajectory can be secured, the elasticity is improved, and the demand is increased. Also has the expected effect.

[Brief description of drawings]

FIG. 1 is a front view of a BB bullet (1) provided with dimples.

FIG. 2 is a side view of a BB bullet (1) provided with dimples.

[Explanation of symbols]

BB bullet with 1 dimple 2 dimples

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kentaro Yoshida             1-3-4 Nishiki-cho, Warabi-shi, Saitama Prefecture

Claims (2)

[Claims] 1. A large number of shallow, watch-glass-shaped depressions (hereinafter referred to as "dimples") are arranged at three-dimensionally symmetrical positions with respect to the center of the sphere on the sphere surface and at positions where the surface arrangement density is uniform. A dimple placement toy BB bullet (hereinafter referred to as a dimple BB bullet). 2. The dimple BB according to claim 1, wherein the position of the three-dimensional symmetry and the uniform arrangement density is the position of each vertex of a regular polyhedron inscribed in a sphere, for example, the position of each vertex of an inscribed regular icosahedron. Bullet.