A structure of a spring bottom hole and a processing method thereof

Abstract

The application discloses a cartridge bottom pocket structure and a processing method thereof, and can improve cartridge stability. The cartridge bottom pocket structure comprises a body provided with a cartridge bottom pocket and a shell pulling hook. The cylindrical surface bottom of the cartridge bottom pocket is provided with a groove. The position of the groove is opposite to the position of the shell pulling hook. The groove is used for locally giving way to the cartridge shell bottom edge. The two ends of the groove and the cylindrical surface of the cartridge bottom pocket form two ridge lines. When the cartridge shell is separated from the cartridge chamber, the shell pulling hook is pushed to the groove direction under the spring force F1 of the shell pulling hook spring. The two ridge lines of the groove are in contact with the cartridge shell bottom edge, forming contact points A and B. The shell pulling hook and the cartridge shell bottom edge groove have a contact point C. The contact points A, B and C constitute three-point positioning.

Description

Technical Field

[0001] This invention relates to the field of firearms technology, and in particular to a bullet base structure and its processing method. Background Technology

[0002] In firearms employing a rigid ejection mechanism, the cartridge case is held in place by the extractor and the cartridge base located on the bolt during ejection. Once the bolt reaches the ejection position, the cartridge case rim contacts the ejector, and the forces of the extractor and ejector create a couple, ejecting the cartridge case from the firearm. However, in practical engineering, the constraint of the cartridge case on the cartridge base is not ideal. First, to ensure that cartridge cases within the upper and lower tolerance limits can enter the cartridge base, the diameter of the cartridge base must be larger than the diameter of the cartridge case rim. Therefore, there is only one contact point between the cartridge case and the cartridge base, which can easily cause swaying parallel to the ejection direction during vibration. Second, to ensure that the extractor can open smoothly and engage the cartridge case rim within the upper and lower tolerance limits, the extractor's hook distance must also be greater than the thickness of the cartridge case rim. This can also easily cause swaying perpendicular to the ejection direction during vibration. Both types of yaw affect the attitude of the cartridge case upon impact with the ejector. If the yaw is too large, the cartridge case will deviate from its designed ejection path and contact locations it shouldn't, such as the upper or lower edges of the ejection port, leading to a jamming failure. Specifically:

[0003] The cartridge base is an important structural component of firearms, typically machined on the bolt or bolt head. Traditionally, the cartridge base is a shallow, cylindrical countersunk hole. Figure 1 As shown, its main working surfaces are the mirror surface 101 and the cylindrical surface 102 of the bullet base, and the mounting hole 103 for the extractor hook is generally machined next to the bullet base.

[0004] To ensure that even cartridge cases at the upper tolerance limit (maximum diameter) can smoothly enter the cartridge base, its size must be at least equal to the maximum diameter of the cartridge rim. Considering that the bolt or bolt head cannot be perfectly coaxial with the barrel, the diameter of the cartridge base needs to be larger than the diameter of the cartridge case rim. For example, if the maximum diameter of the cartridge case rim is 10.5 mm, considering coaxiality deviation, the diameter of the cartridge base should be designed to be 10.6 mm. However, the diameter of the cartridge case rim is generally smaller than the maximum value, often concentrated around 10.4 mm. Therefore, there is generally a 0.2 mm gap between the cartridge case and the cartridge base. The actual case-clamping state is as follows... Figure 2 As shown. Because the diameter of the cartridge base is larger than the diameter of the cartridge case rim, there is only one point of contact between the cartridge base and the cartridge case rim. Figure 2 Point A in the diagram). Although the extractor can be designed to have two contact points with the cartridge case ( Figure 2Points B and C are used for positioning, but because the distance between the two hook tips of the extractor is short (the length of the line connecting points B and C), although it is a three-point positioning, the area of ​​the triangle formed is small, resulting in poor positioning. If the extractor is not machined with high symmetry, it is also very easy to form a single hook tip contact, so the cartridge case only has two contact points for positioning, making the positioning even more inaccurate.

[0005] The distance from the tip of the extractor hook to the mirror surface of the crater is called the hook distance or mirror distance. Figure 3 As shown in L1), to ensure the extractor hook smoothly returns to its original position and engages the cartridge case rim after opening, the hook distance must be greater than the cartridge case rim thickness. For example, for a cartridge case with a rim thickness of 1.5 mm, the hook distance often needs to be designed to be 1.7 mm or more. During firearm use, due to the significant force on the hook teeth, this dimension will further increase due to wear and plastic deformation. Because the distance between the two hook tips (…) Figure 3 The L2 shown is generally around 4 mm thick, therefore the cartridge case rim will have some wobble perpendicular to the ejection direction. This wobble will be particularly large when the cartridge case rim thickness is at its lower limit and the extractor hook distance is at its upper limit. Figure 3 (A1 angle shown). When the cartridge case contacts the ejector in this position, it is prone to impacting the upper or lower edge of the ejection port, causing a jamming failure.

[0006] In summary, the fact that the diameter of the cartridge base is larger than the diameter of the cartridge rim and the hook spacing is larger than the thickness of the cartridge rim determines that the traditional cartridge base structure has an inherent defect in cartridge stability. Therefore, the cartridge stability of the traditional structure is highly dependent on the spring force of the ejector hook spring.

[0007] Increasing the force of the extractor spring improves the clutch stability by increasing the clutch force. However, this method places high demands on the extractor spring. Due to structural space limitations, the extractor spring in firearms cannot be designed with a large force, and even if the force is large, it comes at the cost of lifespan. During use, as the spring force decays, the clutch stability decreases, and the failure rate of jamming increases. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a projectile base structure and its processing method, which can improve the stability of projectile holding.

[0009] The objective of this invention is achieved as follows:

[0010] A cartridge case recess structure includes a body on which the cartridge case recess structure is provided. The body has a cartridge case recess and an extractor hook adjacent to each other. The bottom of the cylindrical surface of the cartridge case recess has a groove. The position of the groove is opposite to the position of the extractor hook. The groove is used to partially make way for the bottom edge of the cartridge case. The two ends of the groove and the cylindrical surface of the cartridge case recess form two ridges. When the cartridge case is released from the constraint of the cartridge chamber, the extractor hook pushes the cartridge case towards the groove under the spring force F1 of the extractor hook spring. The two ridges of the groove contact the bottom edge of the cartridge case, forming contact points A and B. The extractor hook and the bottom edge groove of the cartridge case have a contact point C. Contact points A, B, and C constitute a three-point positioning.

[0011] Preferably, the body is a bolt or a bolt head.

[0012] Preferably, the groove is an arc-shaped groove, and the diameter of the groove is 70%-98% of the diameter of the spring base.

[0013] Preferably, a chamfer / rounded corner is provided between the groove and the upper cylindrical surface of the cartridge case, so that the bottom edge of the cartridge case can be inserted into and removed from the groove, and the height of the cylindrical surface of the groove is less than the minimum thickness of the bottom edge of the cartridge case;

[0014] Due to the presence of chamfers / rounded corners, the chamfers / rounded corners generate a supporting force F2 on the bottom edge of the cartridge case. The component of F2 towards the bottom cavity of the cartridge case causes the cartridge case to fit against the mirror surface of the bottom cavity.

[0015] When the cartridge case wobbles perpendicular to the ejection direction due to vibration, the increased contact force between the chamfer / rounded corner on the opposite side of the wobbling direction and the cartridge case creates a torque that corrects the cartridge case and improves the stability of the cartridge case.

[0016] A method for machining a projectile base structure involves using a disc milling cutter with a diameter of D, a thickness of h, and a top fillet radius of r. The cutter moves along the opposite direction of the ejection direction with an eccentricity of b, close to the mirror surface of the projectile base, to form a groove on the cylindrical surface of the projectile base. D is the diameter of the groove, and the eccentricity b is the maximum depth of the groove.

[0017] Preferably, the difference between the thickness h of the disc milling cutter and the fillet radius r is less than the minimum thickness of the cartridge case bottom edge.

[0018] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0019] This invention features a groove machined on the cartridge base opposite the extractor hook, with a rounded or chamfered corner above the groove. After the cartridge case is released from the chamber, it is pushed into the groove by the extractor hook. The rounded or chamfered corner of the groove helps to confine the cartridge case within the cartridge base, limiting its movement.

[0020] This invention improves the stability of the bolt's case-holding mechanism, effectively solving the problem of increased jamming rates caused by the weakening of the extractor spring force and excessively large extractor distance, leading to instability of the cartridge case on the bolt. It only requires adding a corresponding structure to the cartridge base, without the need for additional parts, and is characterized by its simple structure and ease of implementation. Attached Figure Description

[0021] Figure 1 This is an isometric drawing of the traditional shell base structure, 1-head, 101-shell base mirror surface, 102-shell base cylindrical surface, 103-extractor hook mounting hole;

[0022] Figure 2 This is a view of the traditional cartridge case housing structure in a clutched state, perpendicular to the cartridge case housing mirror surface. The cartridge case related structures are represented by dashed lines: 1-nose, 2-extractor, 301-cart case rim, 302-cart case rim groove.

[0023] Figure 3 This is a schematic diagram of a conventional cartridge case retainer structure where the cartridge case sways perpendicular to the ejection direction. 1-Nose, 3-Cartridge case, 201-Projection of the extractor hook teeth.

[0024] Figure 4 This is an isometric view of the bullet base structure of the present invention, 1-head, 104-groove, 105-ridge line;

[0025] Figure 5 This is a schematic diagram of the machining of the bullet base of the present invention, 1-machine head, 4-tool, 401-tool center;

[0026] Figure 6 This is a schematic diagram of the cartridge case in a state perpendicular to the bottom mirror surface of the cartridge case. The cartridge case related structures are represented by dashed lines: 1-machine head, 2-extractor, 301-cart case bottom edge, 302-cart case bottom edge groove.

[0027] Figure 7 This is a schematic diagram of the invention for limiting cartridge case sway, 1 - machine head, 104 - groove, 3 - cartridge case, 301 - cartridge case bottom edge, 302 - cartridge case bottom edge groove. Detailed Implementation

[0028] The invention will be further described below with reference to the accompanying drawings.

[0029] A cartridge base structure includes a body on which the cartridge base structure is disposed, wherein the cartridge base and an extractor are disposed adjacently on the body, and the body is a bolt or a bolt head. In this embodiment, the body is a bolt head.

[0030] This invention adds a groove to the opposite cylindrical surface of the pull-out hook, partially allowing space for it to extend. The two ends of the groove form two ridges 105 with the cylindrical surface of the spring base. Figure 4As shown. For ease of processing, the groove is designed as an arc, with its diameter slightly smaller than the diameter of the cartridge case's bottom rim. For example, for a cartridge case bottom rim with a diameter of 10.5 mm, the diameter can be 8-10 mm. The cross-sectional shape of the groove is crucial for cartridge case stability and ejection. It must be designed with a chamfered or rounded corner structure at the top. A right-angled structure will not improve cartridge case stability, and the cartridge case bottom rim will be unable to dislodge after being inserted, affecting ejection. This embodiment uses a rounded corner structure, as shown... Figure 5 As shown. When the cartridge case is extracted from the chamber by the extractor, the extractor presses the cartridge case towards the eccentric recess. The recess limits the bottom edge of the cartridge case, making it difficult for the cartridge case to wobble, thereby improving the cartridge case's holding stability and reducing the probability of jamming.

[0031] Processing method:

[0032] Using a conventional cartridge case recess structure as the machining target, a disc milling cutter with a diameter of D, a thickness of h, and a top fillet radius of r is moved eccentrically by a distance b along the mirror surface of the cartridge case recess in the opposite direction to the ejection direction (the direction of the extractor's action), forming a groove on the cylindrical surface of the cartridge case recess. It is important to note that the cutter thickness h minus the fillet radius r should be less than the minimum thickness of the cartridge case rim. For example, for a cartridge case with a minimum rim thickness of 1.35 mm, the value of h can be designed as 1.8, and the value of r as 0.5.

[0033] The following explains the principle by which this structure improves shell stability:

[0034] like Figure 6 As shown, after the cartridge case is released from the chamber, the extractor pushes it towards the groove. The two edges 105 of the groove contact the cartridge case's bottom edge 301, forming contact points A and B. Ideally, the arc diameter of the extractor's teeth should be equal to or slightly larger than the diameter of the groove on the cartridge case's bottom edge, resulting in only one contact point C between the extractor and the groove 302. The contact point of the extractor and the contact point of the groove constitute a three-point positioning system. Because the two apexes A and B of the groove are far apart, the area of ​​the triangle formed is larger than that of the traditional structure, preventing the cartridge case from translating within the plane of the cartridge case's bottom edge, thus making the positioning more stable.

[0035] like Figure 6 As shown, after the cartridge case is released from the chamber, the extractor, under the action of spring force F1, pushes the cartridge case towards the groove, causing it to partially embed into the groove and be positioned by the two cusps of the groove. Due to the presence of rounded or chamfered corners, the rounded corners generate a supporting force F2, and F2 has a component force towards the cartridge base, causing the cartridge case to adhere to the mirror surface of the cartridge base. At the same time, when the cartridge case wobbles perpendicular to the ejection direction due to vibration, the contact force between the rounded corner on the opposite side of the wobbling direction and the cartridge case increases, forming a torque that corrects the cartridge case and improves the stability of the cartridge case.

[0036] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A projectile base structure, comprising a body having the projectile base structure, wherein the body has adjacent projectile bases and extractor hooks, characterized in that: The bottom of the cylindrical surface of the cartridge case recess is provided with a groove, the position of which is opposite to the position of the extractor. The groove is used to partially make way for the bottom edge of the cartridge case. The two ends of the groove and the cylindrical surface of the cartridge case recess form two ridges. When the cartridge case is released from the constraint of the cartridge chamber, the extractor pushes the cartridge case towards the groove under the action of the spring force F1 of the extractor spring. The two ridges of the groove contact the bottom edge of the cartridge case, forming contact points A and B. The extractor and the bottom edge groove of the cartridge case have a contact point C. Contact points A, B, and C constitute three-point positioning. The main body is a bolt or bolt head; A chamfer / rounded corner is provided between the groove and the upper cylindrical surface of the cartridge case, so that the bottom edge of the cartridge case can be inserted into and removed from the groove, and the height of the cylindrical surface of the groove is less than the minimum thickness of the bottom edge of the cartridge case. Due to the presence of chamfers / rounded corners, the chamfers / rounded corners generate a supporting force F2 on the bottom edge of the cartridge case. The component of F2 towards the bottom cavity of the cartridge case causes the cartridge case to fit against the mirror surface of the bottom cavity. When the cartridge case wobbles perpendicular to the ejection direction due to vibration, the increased contact force between the chamfer / rounded corner on the opposite side of the wobbling direction and the cartridge case creates a torque that corrects the cartridge case and improves the stability of the cartridge case.

2. The projectile base structure according to claim 1, characterized in that: The groove is an arc-shaped groove, and the diameter of the groove is 70%-98% of the diameter of the spring base.

3. A method for processing the projectile base cavity structure according to claim 1, characterized in that, A disc milling cutter with diameter D, thickness h, and top fillet r moves along the opposite direction of the ejection direction with an eccentricity b, close to the mirror surface of the ejection socket, to form a groove on the cylindrical surface of the ejection socket. D is the diameter of the groove, and the eccentricity b is the deepest point of the groove.

4. The processing method of the bullet base cavity structure according to claim 3, characterized in that: The difference between the thickness h of the disc milling cutter and the fillet radius r is less than the minimum thickness of the cartridge case bottom edge.

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