Manufacturing method for air guns and their inner barrels

Abstract

To provide a new air gun and a manufacturing method of an inner barrel thereof capable of exhibiting excellent hit accuracy and extending a flying distance of a spherical bullet.SOLUTION: An air gun 100 comprises an inner barrel 10 which allows a spherical bullet BB to pass through and to be fired from its tip, and a part or the whole of the inner barrel 10 is in a cross section substantially regular triangle. Thus, a high-speed backspin state of the spherical bullet BB passing through the inner barrel 10 can be maintained, then its flying distance can be extended while preventing reduction of rotation frequency. In addition, hit accuracy is improved as the spherical bullet BB can be fired while being positioned at an axis part of the inner barrel.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an air gun that fires spherical projectiles such as BB bullets using gas pressure and a method for manufacturing its inner barrel.

Background Art

[0002] Generally, in an air gun that uses plastic spherical projectiles such as BB bullets, not only is the spherical projectile simply fired using gas pressure, but also the flight distance is extended or the hitting accuracy is improved by imparting a rotational motion to the spherical projectile during firing. For example, in Patent Document 1 below, when firing a spherical projectile, the spherical projectile is rotated in a direction around the direction of travel to give a gyroscopic effect to the flying spherical projectile, thereby stabilizing the flight trajectory during flight and improving the hitting accuracy.

[0003] Also, in Patent Document 2 below, when firing a spherical projectile, an upward rotational motion (backspin) is imparted to the spherical projectile by pressing the upper part of the spherical projectile against a rubber protrusion or a roller packing to generate lift force on the spherical projectile, thereby extending the flight distance. Further, in Patent Document 3 below, a rubber protrusion is also provided near the gun barrel in the gun body, and the upper part of the spherical projectile is sequentially brought into contact with the two rubber protrusions to maintain the backspin state and avoid a decrease in the flight distance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in order to rotate a spherical projectile in a direction with respect to its direction of travel as shown in Patent Document 1, a motor, gears, battery, and connectors are required to rotate the barrel, which increases costs and the overall weight of the air gun. Also, when the projectile stalls, its trajectory becomes irregular, reducing accuracy. Furthermore, in the methods shown in Patent Documents 2 and 3, the spherical projectile decelerates when it comes into contact with rubber protrusions or the inner surface of the barrel multiple times during firing, which may reduce its range and accuracy.

[0006] Therefore, the present invention was devised to solve these problems, and its objective is to provide a novel air gun and a method for manufacturing its inner barrel that can achieve excellent accuracy without incurring costs and can also extend the range of spherical projectiles. [Means for solving the problem]

[0007] To solve the aforementioned problems, the first invention is an air gun equipped with an inner barrel that passes a spherical bullet through and fires it from its tip, characterized in that part or all of the inner barrel has a roughly equilateral triangular cross-section. With this configuration, the high-speed backspin state of the spherical bullet passing through the inner barrel can be maintained, thus preventing a decrease in rotation speed and extending its range. In addition, since the spherical bullet can be fired while being positioned at the axis of the inner barrel, accuracy is improved. Furthermore, since these effects can be obtained simply by processing the inner barrel, the increase in cost can be kept down.

[0008] The second invention is an air gun equipped with an inner barrel that passes a spherical bullet through and fires it from its tip, characterized in that the area near the tip of the inner barrel has a roughly equilateral triangular cross-section. With this configuration, the effects of the first invention can be obtained more reliably.

[0009] The third invention is an air gun characterized in that the area near the tip of the inner barrel has a roughly triangular cross-section with one corner facing the direction of gravity. With this configuration, in addition to the effects of the first and second inventions, high-speed backspin can be imparted, thereby further extending the range of the spherical projectile.

[0010] The fourth invention is a method for manufacturing an inner barrel for an air gun according to any one of the first to third inventions, characterized by comprising the steps of: inserting a core rod with a diameter less than or equal to the diameter of the spherical bullet into a metal tube having a perfectly circular cross-section; and pressing the portion in which the core rod is inserted in the axial direction with three mold parts located around it to press it into a substantially equilateral triangle cross-section. With such a manufacturing method, an inner barrel having a substantially equilateral triangle cross-section can be easily manufactured. [Effects of the Invention]

[0011] According to the present invention, the spherical bullet can maintain a high-speed backspin state as it passes through the inner barrel, thereby preventing a decrease in rotation speed and extending its range. Furthermore, because the spherical bullet can be positioned at the axis of the inner barrel while being fired, accuracy is improved. Moreover, since these effects can be obtained simply by modifying the inner barrel, it exhibits excellent advantages such as keeping costs down. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram showing one embodiment of the air gun 100 according to the present invention. [Figure 2] This is a cross-sectional view showing the inner barrel 10. [Figure 3] Figure 2 shows an enlarged cross-sectional view along line AA. [Figure 4] Figure 2 shows an enlarged cross-sectional view of line BB. [Figure 5] This is an explanatory diagram showing the movement of a spherical bullet (BB) as it passes through the inner barrel 10. [Figure 6] This is an enlarged view of section A in Figure 5. [Figure 7] This is an explanatory diagram showing the manufacturing method of the inner barrel 10. [Modes for carrying out the invention]

[0013] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 shows one embodiment of the air gun 100 according to the present invention. Reference numeral 10 in the figure indicates an inner barrel 10 through which a spherical bullet BB passes, and an air cylinder 30 is connected to one end thereof via a chamber 13. This inner barrel 10 is covered by an outer barrel 20, and this outer barrel 20 is integrated with the gun body 90 which houses the air cylinder 30 and the like.

[0014] The air cylinder 30 houses a piston 50 that is operated by a spring 40 and is capable of reciprocating motion, and its movement is controlled by a trigger 60, sear 70, etc., which are also attached to the gun body 90. The gun body 90 is also provided with a magazine (not shown) for storing spherical bullets BBs, and the spherical bullets BBs are sequentially supplied into the chamber 13 via a supply passage 80.

[0015] Here, the method for operating the piston 50 in the air cylinder 30 can be conventionally known air cocking (manual) or electric, and the method is not particularly limited in this embodiment. Similarly, the form of the gun body 90 is not particularly limited and may be a revolver type, rifle type, handgun type, machine gun type, etc., as in the past. Furthermore, a system using vaporized gas instead of the air cylinder 30 may also be used.

[0016] The inner barrel 10 is composed of a metal tube such as brass, aluminum, or stainless steel. For example, its size is a length of 200 - 210 mm, and if the inner diameter is such that the diameter of the spherical bullet BB is 5.95 mm, it is sized to allow the bullet to pass through smoothly, for example, about 6.01 - 6.10 mm. And as shown in FIG. 2, a part of this inner barrel 10, for example, the cross-sectional shape of the vicinity of the tip P near the muzzle 11 about 20 - 40 mm is a substantially regular triangle in cross-section as shown in FIG. 3.

[0017] That is, as shown in FIG. 4, the substantially entire inner barrel 10 has a circular cross-section so that the spherical bullet BB can pass through smoothly, but only the vicinity of the tip P has a cross-section that is a substantially regular triangle (a triangular rice ball shape) with each of the three corners gently curved. And as shown in FIG. 3, the diameter d of the circle inscribed in the three inner surfaces P1, P2, and P3 of the vicinity of the tip P is slightly larger than the diameter of the spherical bullet BB, for example, about 6.00 - 6.05 mm.

[0018] Furthermore, as shown in the same figure, the vicinity of the tip P of this inner barrel 10 has a downward cross-section that is a substantially triangular shape with one corner facing the direction of gravity. Therefore, the spherical bullet BB that reaches the vicinity of the tip P passes through while contacting one of the inner surfaces of this downward cross-section that is substantially triangular, that is, either the upper surface P1 or the two side surfaces P2 and P3 that are inclined obliquely downward as shown in FIG. 3.

[0019] Next, the operation of the air gun 100 according to the present invention equipped with such an inner barrel 10 will be described as follows. As shown in FIG. 1, the spherical bullet BB supplied into the chamber 13 is vigorously passed through the inner barrel 10 by the gas pressure supplied from the air cylinder 30 that operates by the operation of the trigger NO. 60 and is fired from the muzzle 11. At this time, since a rubber upper protrusion 12 is provided above the firing end of the inner barrel 10, the spherical bullet BB passes through the inner barrel 10 while rotating upward (backspin) as its upper part contacts this upper protrusion 12.

[0020] When the spherical bullet BB passes through the inner barrel 10, if it contacts the upper surface of the inner barrel 10 as shown by the symbol S1 in Figure 5, it will maintain its upward rotation or even increase its rotational speed. Conversely, if it contacts the lower surface of the inner barrel 10 as shown by the symbol S2, a force opposite to the upward rotation will act on the spherical bullet BB, causing its upward rotational speed to decrease.

[0021] However, as mentioned above, the inner barrel 10 according to the present invention has a roughly triangular cross-section with a downward-facing tip P. As shown in Figure 3, the spherical bullet BB passing through this area will not come into contact with the lower surface of the inner barrel 10. Therefore, no force acting in the opposite direction to the upward rotation will be applied, and a high-speed backspin state can be maintained.

[0022] In other words, if the spherical bullet BB contacts only the upper surface P1 of this downward-facing, approximately triangular cross-section as it passes near the tip P, it will act in a way that maintains or enhances the upward rotation, similar to the case indicated by the symbol S1 in Figure 5. On the other hand, even if the spherical bullet BB contacts both sides P2 and P3, which are inclined diagonally downwards, as it passes near the tip P, the contact point is near the axis of rotation of the spherical bullet BB, so a large reaction force like that in the case indicated by the symbol S2 in Figure 5 does not act, thus avoiding a significant decrease in the upward rotation speed.

[0023] Furthermore, as shown in Figure 6, a large gap C is created at the bottom of the spherical bullet BB as it passes near the tip P. As gas passes through this gap with force, an upward rotational force is imparted to the spherical bullet BB. This allows the spherical bullet BB to be launched while maintaining a high-speed backspin state, thus preventing a decrease in rotational speed and further extending its range.

[0024] Furthermore, as the spherical bullet BB passes near the tip P of this downward-facing, roughly triangular cross-section, it is naturally positioned at the axis of the inner barrel 10. As shown in Figure 5, it is then fired straight out of the muzzle 11 without contacting the inner surface of the inner barrel 10, resulting in a stable trajectory during stall and a significant improvement in accuracy.

[0025] Furthermore, while it is possible to process not just a portion of the inner barrel 10, but the entire barrel into a roughly triangular cross-section, as long as at least both ends remain perfectly circular as before, the existing outer barrel 20 and chamber 13 can be used as is without having to newly manufacture or modify them. In other words, since only the inner barrel 10 needs to be replaced from the existing airsoft gun, these effects can be obtained at a low cost.

[0026] Another method for machining a portion of the inner barrel 10 into a roughly triangular cross-section involves, for example, preparing three mold parts K, K, K shaped like hydraulic chucks, as shown in Figure 7, and arranging them around a portion of the circular cross-section metal tube 10a that will become the inner barrel 10. Then, by inserting a metal spindle R into the area to be machined and then applying pressure (pressing) the mold parts K, K, K from three sides in the axial direction, only that portion can be easily machined into a roughly triangular cross-section. It is desirable that the diameter of this spindle R be the same as or less than the diameter of a spherical bullet BB, for example, around 6.0 to 5.5 mm, taking into account the rebound of the material after press working. [Explanation of symbols]

[0027] 10... Inner barrel 10a…Metal pipe 11…Muzzle 12...Top projection 13… Chamber 20... Outer barrel 30... Air cylinder 31…Nozzle 40... Spring 50... Piston 60... Trigger 70... Shea 80…Supply passage 90... Gun body 100... Airgun BB... Spherical bullet C... Gap K... Mold parts P...near the tip R…Mandrel

Claims

1. An air gun comprising an inner barrel through which a spherical projectile passes, and an upper projection that imparts upward rotation to the spherical projectile as it passes through the inner barrel during firing, An air gun characterized in that part or all of the inner barrel has a roughly equilateral triangle cross-section, and the roughly equilateral triangle cross-section is a downward-pointing triangle with one corner facing the direction of gravity.

2. An air gun comprising an inner barrel through which a spherical bullet passes, the inner barrel for firing the spherical bullet from its tip, and an upper projection for imparting upward rotation to the spherical bullet as it passes through the inner barrel during firing, An air gun characterized in that the area near the tip of the inner barrel has a roughly equilateral triangle cross-section, and that the roughly equilateral triangle cross-section is a downward-pointing triangle with one corner facing the direction of gravity.

3. A method for manufacturing an inner barrel for an air gun according to claim 1 or 2, A step of inserting a core rod, which is the same diameter as or less than the diameter of the spherical bullet, into a metal tube having a perfectly circular cross-section, A method for manufacturing an inner barrel for an air gun, comprising the steps of: pressing the metal tube, into which the core rod is inserted, in the axial direction of the metal tube with three mold components located around the metal tube to press it into a substantially equilateral triangle in cross-section.

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