KR102645384B1 - --BMB omitted - Google Patents

Abstract

The present invention proposes a BMB clad metal structure instead of single copper or brass as a metal material for warhead cups, thereby realizing weight reduction and economic efficiency by lowering the copper content, while achieving superior heat resistance and formability than single copper or brass, and a warhead cup material with improved durability and hardness. It relates to single-column-mild steel-single-couple metal materials for warhead cups to replace single-column and brass that can be obtained.
For this purpose, the present invention includes a mild steel layer; A first monolithic layer laminated on the first side of the mild steel layer and integrally bonded; And a second single layer is laminated on the second surface of the mild steel layer in the opposite direction of the first single layer and is integrally bonded.

Description

Single acting-mild steel-single acting (BMB) metal material for warhead cups to replace single acting and brass{omitted}

The present invention relates to metal materials. More specifically, it relates to single-mild steel-single-barreled (BMB) metal materials for warhead cups to replace single-barrel and brass.

Red brass or brass is used for golden metal fittings or accessories for architecture and furniture, and because of its good cold workability, it is also used for electronic components, currency, medals, as well as warheads and shell casings.

Brass is used in various fields such as accessories, pipes, furniture, musical instruments, grills, tableware, and valves.

Brass is easy to cast and has good processability, so it is suitable for rolling and forging, and is also widely used as a material for warheads and bullet casings.

It is known that the surface of the warhead has a significant effect on the accuracy of hitting the target. If the surface of the warhead is not uniform, the accuracy may be reduced and it may be treated as a defect.

Warheads are generally manufactured at a metal processing company by processing a single brass or brass plate into a cup shape as shown in FIG. 1 using a drawing method (hereinafter referred to as 'warhead cup'), and then reprocessing it into the desired shape at the weapons manufacturer.

In the case of single-acting or brass, when processed into a warhead cup by the drawing method, an earing phenomenon may occur as shown in the left drawing of Figure 1 (the drawing on the right is a normal processed product).

Additionally, in the case of single brass or brass, when processed into a warhead cup using the drawing method, a ridging phenomenon may occur as shown in the left drawing of Figure 2 (the drawing on the right is a normal processed product). The ridging phenomenon is the formation of groove-like irregularities in one direction on the surface of the warhead cup.

Bullets can be broadly divided into ordinary bullets and tracer bullets.

Ordinary rounds are the most common combat and training rounds and are used to fire at enemy troops and unarmored targets.

Tracer bullets contain a tracer that emits light inside the warhead, and as the tracer burns, the trajectory of the warhead is visible.

Tracer bullets, like regular bullets, are made of single copper or brass. Single copper and brass have weak heat resistance and low melting points, so there is a problem in that they cannot properly perform the function of tracer bullets due to warhead shape deformation.

In addition, single copper and brass have the following problems for warheads.

First, it is vulnerable to moisture, so there is a high possibility of natural cracks occurring.

In particular, products containing more than 20% by weight of zinc are vulnerable to humidity. In addition, the ammonia component in the air causes the surface of brass products to crack, and to prevent this, surface treatments such as stress relief, painting, and plating are required.

Second, because secular changes occur, brass materials obtained by leaving brass processed materials at room temperature or by low-temperature annealing hardening have the problem that physical properties such as hardness deteriorate and durability decreases over time of use.

Third, because of its high specific gravity, lightweighting is difficult.

Lightweight is an important issue related to the ammunition's range and also affects the ammunition's portability.

Fourth, there is a disadvantage in that price competitiveness is reduced due to the increase in the price of raw materials copper and zinc, especially copper.

In the United States, plastic warheads were developed in the 2000s to replace expensive brass warheads, but commercialization failed.

In order to solve these problems, there is a need to develop technology for metal materials for warhead cups that can replace brass and improve the various physical properties mentioned above.

Prior art literature: KR Registered Patent Publication No. 1131864 (2012.03.23)

The present invention was made to solve the above problems, and in particular, the purpose is to solve the shortcomings of single copper and brass as warhead cup materials and to provide a metal material for warhead cups with excellent economic efficiency and physical properties.

The single-mild steel-single brass (BMB) metal material for warhead cups to replace single brass and brass according to the present invention invented to achieve the above object includes a mild steel layer; A first monolithic layer laminated on the first side of the mild steel layer and integrally bonded; and a second single copper layer that is laminated on the second surface of the mild steel layer in the opposite direction to the first single copper layer and is integrally bonded.

According to an embodiment of the present invention, a plate-shaped metal material in which a first single layer, a mild steel layer, and a second single layer are laminated is first processed into a cup-shaped warhead cup having an upper opening and a lower closed portion by a drawing method, Warheads are manufactured through secondary processing by adjusting the inner diameter of the warhead cup and the radius of curvature of the bottom closure according to the bullet's specifications and use. In the primary processing, a plate made of single copper or brass is used to close the top opening and bottom using a drawing method. In the case of primary processing into a cup shape with a portion, the first probability (P ₁ ) of earing phenomenon occurring due to non-uniformity of the surface and weight of each part or slip in the thickness direction, and lamination with BMB by atomic diffusion bonding. When the sheet material is first processed into a cup shape with an upper opening and a lower closing part by the drawing method, the BMB bonding interface suppresses atomic layer slip in each of the first single layer, mild steel layer, and second single copper layer, thereby forming an overall thickness direction. The relationship between the second probability (P ₂ ) of occurrence of the earing phenomenon is 0 ≤ P ₂ ＜ P ₁ ≤ even though mild steel has greater tensile strength and formability than solid steel or brass and thus causes less structural change during drawing. It is characterized by 1.

In addition, according to an embodiment of the present invention, the specific gravity is reduced by more than 7% compared to the brass metal material of the same volume and by more than 9% compared to the single copper metal material, and the thickness ratio of the first single copper layer, mild steel layer, and second single copper layer is 5 to 7: 80~90: 5~15, the weight ratio of the first single copper layer, mild steel layer, and second single copper layer is 5.5~7.7:78.1~88.9:5.5~16.4, the weight ratio of the first single copper layer, mild steel layer, and second single copper layer is 5.5~7.7:78.1~88.9:5.5~16.4. The weight ratio per square meter is 0.4400~0.6160 : 6.2800~7.0650 : 0.44~1.32, the weight ratio of single copper in the total is 11.1~21.9%, and mild steel reinforces the hardness of single copper, making it harder than single copper or brass metal of the same volume. The thermal conductivity of mild steel is lower than that of single copper or brass, and the melting point of mild steel is higher than that of single copper or brass, so it has better heat resistance and lower thermal conductivity than single copper or brass metal of the same volume, and has a lower copper content than single copper or brass metal of the same volume. It is characterized by less.

According to the present invention, by presenting a BMB clad metal structure instead of brass as the metal material for the warhead cup, it is possible to obtain a warhead cup material with improved durability and hardness, while realizing weight reduction and economic efficiency by lowering the copper content, and having superior heat resistance and formability than brass. There is an effect.

In addition, according to the present invention, when applied to ordinary bullets, there is an effect of preventing excessive penetration and securing accuracy and stopping power.

In addition, according to the present invention, when applied to tracer bullets, the thermal conductivity is low and heat resistance is excellent compared to existing single cylinders and brass, which has the effect of preventing changes in the shape of the warhead and faithfully implementing the function of the tracer bullet.

Figures 1 and 2 are conceptual diagrams for explaining the earing phenomenon and the ridging phenomenon.
Figure 3 is a vertical cross-sectional view of a single-acting-mild steel-single-acting metal material for a warhead cup to replace single-acting and brass according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. First, when adding reference signs to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted. In addition, preferred embodiments of the present invention will be described below, but the technical idea of the present invention is not limited or restricted thereto, and of course, it can be modified and implemented in various ways by those skilled in the art.

Figure 3 is a vertical cross-sectional view of a single-mild steel-single brass (BMB) metal material for a warhead cup to replace single brass and brass according to a preferred embodiment of the present invention. Hereinafter, the single-mild steel-single-column metal material will be referred to as BMB (Brass Mild steel Brass) metal material.

Referring to Figure 3, the BMB metal material for the warhead cup for replacing single-acting and brass according to a preferred embodiment of the present invention includes a mild steel layer (10), a first single-acting layer (20), and a second single-acting layer (30). It comes true.

The mild steel layer 10 is a layer made of mild steel, and has a low carbon content compared to hard steel, making it relatively ductile. Mild steel is carbon steel with a carbon content of around 0.2%.

More specifically, carbon steel is classified into ultra-soft steel with a carbon content of 0.2% or less, mild steel with a carbon content of 0.12 to 0.20%, semi-mild steel with a carbon content of 0.2 to 0.3%, radius steel with a carbon content of 0.3 to 0.4%, and light steel with a carbon content of 0.4 to 0.5%. In the present invention, Mild steel is used as a concept encompassing extremely mild steel, mild steel, semi-mild steel, and radius steel.

The specific gravity of the mild steel layer 10 is 7.8 to 7.9, and for example, one with a specific gravity of 7.85 can be used.

The tensile strength of the mild steel layer 10 is 38 kgf/㎟ or more. For example, one with a tensile strength of around 40 kgf/㎟ can be used.

The microscopic structure of the mild steel layer 10 is ferrite and pearlite in the soaked state, and as the carbon content increases, the specific gravity of pearlite increases.

The properties of the mild steel layer 10 may change at room temperature or high temperature due to quenching aging and strain aging, which is due to carbon and nitrogen dissolved in solid solution as ferrite.

As the mild steel layer 10, SPCC (Steel Plate Cold Commercial), a cold rolled steel plate, may be used, but is not limited thereto. SPCC has excellent processability to the extent that it can be rolled at room temperature and has a clean surface.

The first monolithic layer 20 is laminated on the first side of the mild steel layer 10 and is integrally bonded.

The second single copper layer 30 is laminated on the second surface of the mild steel layer 10 in the opposite direction to the first single copper layer 20 and is integrally bonded.

The mild steel layer 10, the first single layer 20, and the second single layer 30 are laminated and joined through a slitting process, surface processing process, bonding process, heat treatment process, cold rolling process, and shape correction process. You can.

The slitting process is a process of cutting raw materials to an appropriate width. In the slitting process, single and mild steel are input into the slitter line and cut in the width direction parallel to the direction of travel.

The surface processing process performs processing to expand the surface area for smooth bonding between each layer.

The joining process places the mild steel between two rotating rollers each wound with a single-acting material, so that the mild steel is pressed between the single-acting materials on both sides. In the joining process, brass and mild steel are joined only by the force acting on the surface of the roller on which both rotating single-acting materials are wound.

The heat treatment process uses one or more gases selected from hydrogen and nitrogen, followed by gradual cooling. The heat treatment process softens the structure of each raw material hardened in the joining process to lower hardness and improves processability and workability in the rolling process, which is a post-processing process. The reason for heat treatment using hydrogen and nitrogen gas in the heat treatment process is to prevent surface corrosion, improve surface condition, and uniformize the metal structure of mild steel and single copper.

The rolling process involves rolling to reduce the thickness to a preset target thickness.

The shape correction process is a process of securing flatness by applying a strong tensile force to the deformed shape through rolling and heat treatment. The shape correction process is a process of securing flatness by repeatedly bending and correcting the deformed shape through rolling and heat treatment, and applying a certain tensile force to correct the shape. The shape can be corrected by sequentially processing the flattening correction roller.

In an embodiment in which the first single layer 20 and the second single layer 30 have a specific gravity of 8.8, and the mild steel layer 10 has a specific gravity of 7.85, when the total thickness of the BMB metal material is 1 mm, the total specific gravity is 7.95, square The weight per meter is 7.950g.

In addition, the BMB metal material for warheads for replacing single-acting and brass according to the present invention has a specific gravity of 8.8 for the first single-acting layer 20 and the second single-acting layer 30, which are relatively thin, while the relatively thick mild layer has a thickness of 8.8. Since the specific gravity of the steel layer 10 is 7.85, the overall specific gravity is 7.95.

On the other hand, the specific gravity of single copper is 8.80 and the specific gravity of brass is 8.54, which is heavier than the BMB metal material for warheads to replace single copper and brass according to the present invention, so the purpose of lightening cannot be achieved in the technology behind the invention. It has been mentioned.

Lightweighting has the advantage of increasing the bullet's range and making it easier to handle.

The specific gravity of the BMB metal material compared to brass is 7.95 / 8.54 ≒ 0.93, and the specific gravity of the BMB metal material for warheads to replace brass according to the present invention is reduced by approximately 7% or more compared to the brass metal material, and compared to single-acting, the specific gravity is reduced by approximately 9% or more. products can be implemented.

The first single layer 20, the mild steel layer 10, and the second single layer 30 that make up the BMB metal material can be combined with each other at various thickness ratios and weight ratios. In addition, the first single layer 20 and the second single layer 30 are generally manufactured to the same thickness, but may be manufactured to different thicknesses.

The thickness ratio of the first single layer, the mild steel layer, and the second single layer can be implemented as 5~7:80~90:5~15. For example, the thickness ratio may be implemented as B:M:B = 5:90:5, but is not limited thereto.

The weight ratio of the first single layer, the mild steel layer, and the second single layer can be implemented as 5.5 to 7.7: 78.1 to 88.9: 5.5 to 16.4. For example, the weight ratio may be implemented as B:M:B = 5.55:88.9:5.55, but is not limited thereto.

The weight ratio per square meter of the first single layer, mild steel layer, and second single layer can be implemented as 0.4400~0.6160:6.2800~7.0650:0.44~1.32. For example, the weight ratio per square meter can be implemented as B:M:B = 0.4400 : 7.0650 : 0.4400, but is not limited to this. At this time, the weight ratio per square meter is calculated when the total thickness of the BMB metal material is 1 mm, the total specific gravity is 7.95 to 8.04, and the weight per square meter is 7.950 to 8.040, and the thickness ratio of the BMB varies.

The weight ratio of single copper in the entire BMB metal material is 11.1 to 21.9% because it is the weight of the entire BMB metal material excluding the mild steel layer. Therefore, since the content of single copper is only 11.1 to 21.9% compared to a metal material made of only single copper, BMB metal material has physical properties of single copper that are not suitable as a warhead cup, such as weight, price (copper content is less than that of single copper metal material of the same volume), and thermal conductivity. , hardness, etc. can be solved.

On the other hand, if the combined fraction (based on thickness) of the first single copper layer 20 and the second single copper layer 30 exceeds 20%, the weight increases and the cost increases considering the purpose of the present invention to replace the single copper layer. There is a problem.

If the combined fraction of the first single copper layer 20 and the second single copper layer 30 is less than 10%, there is a problem in that the mechanical stability and bonding strength of the clad cannot be sufficiently secured.

In other words, the above weight ratio was calculated experimentally by ensuring heat resistance and considering weight, as well as cost, hardness, and strength.

Additionally, mild steel reinforces the hardness of the single-acting material, making it harder than single-acting metal material of the same volume.

Since the Vickers hardness of mild steel is greater than the Vickers hardness of single-acting steel, the hardness of the BMB metal material whose base material is mild steel is greater than that of the metal material made only of single-acting material, reinforcing the hardness of the single-acting material. In reality, the hardness of BMB metal material is almost equivalent to that of mild steel. It was confirmed experimentally that it had a value.

In addition, the thermal conductivity of mild steel is lower than that of single copper or brass, and the melting point of mild steel is higher than that of single copper or brass, so BMB metal material has better heat resistance and lower thermal conductivity than single copper or brass metal material of the same volume.

For example, the thermal conductivity of single copper is 189 W/mK, the thermal conductivity of brass is 116 W/mK, the thermal conductivity of mild steel is 74 W/mK, the melting point of single copper is 1020 to 1045 degrees Celsius, and the melting point of brass is 905 to 930 degrees Celsius. If the melting point of mild steel is 1530 degrees Celsius, the BMB metal material whose base material is mild steel exhibits heat-resistant properties compared to single copper or brass.

Due to the characteristics of the BMB metal material, when applied to tracer bullets, it prevents the heat generated during firing from being directly transmitted to the tracer and prevents deformation of the warhead, making it possible to see the trajectory of the bullet with the naked eye.

Warheads are manufactured through primary and secondary processing.

In the primary processing, a plate-shaped metal material in which the first single layer, the mild steel layer, and the second single layer are laminated is processed into a cup-shaped warhead cup with an upper opening and a lower closed portion by a drawing method.

In secondary processing, the warhead is manufactured by adjusting the inner diameter of the warhead cup and the radius of curvature of the lower closure part according to the bullet's specifications and purpose.

In the primary processing, when a plate made of single copper or brass is first processed into a cup shape with an upper opening and a lower closed portion by the drawing method, the probability of the earing phenomenon occurring is called the first probability (P ₁ ), and is referred to as atomic diffusion bonding. If the second probability (P ₂ ) is the probability that the earing phenomenon occurs when a plate laminated with BMB is first processed into a cup shape with an upper opening and a lower closed portion by the drawing method, then between P ₁ and P ₂ The following relationship is established:

0 ≤ P ₂ ＜ P ₁ ≤ 1

In other words, the BMB metal material can relatively lower the probability of the earing phenomenon occurring compared to the single-acting metal material or brass metal material during primary processing into the warhead cup.

In the case of single-coupled metal or brass metal, the possibility of earing phenomenon occurring due to non-uniformity of the surface and weight of each part or slip in the thickness direction is relatively high, whereas for BMB metal, the BMB joint boundary is the first single-couple layer, mild By suppressing atomic layer slip in each of the steel layer and the second single-layer layer, slip in the overall thickness direction is suppressed.

Since the bonding interface between the single copper layer and the mild steel layer exhibits different interface characteristics from the atomic arrangement within the single copper layer or the atomic arrangement within the mild steel layer, the slip in the thickness direction inside the single copper layer is directly transmitted to the mild steel layer through the bonding interface. It cannot be done and is suppressed.

In addition, mild steel has greater tensile strength and formability than single copper or brass, showing less structural change during drawing, so the possibility of the earing phenomenon occurring can be relatively lowered.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications, changes, and substitutions can be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the attached drawings are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments and the attached drawings. . The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

10: Mild steel layer
20: first single layer
30: second single layer

Claims (3)

Mild steel layer encompassing extremely mild steel, mild steel, semi-mild steel, and radius steel;
A first monolithic layer laminated on the first side of the mild steel layer and integrally bonded; and
A second single copper layer is laminated on the second side of the mild steel layer in the opposite direction to the first single copper layer and is integrally bonded.
Including,
After first processing the plate-shaped metal material in which the first single layer, the mild steel layer, and the second single layer are laminated, into a cup-shaped warhead cup having an upper opening and a lower closed portion by a drawing method,
Warheads are manufactured through secondary processing by adjusting the inner diameter of the warhead cup and the radius of curvature of the bottom closure according to the bullet's specifications and use.
In the primary processing, when a plate made of single copper or brass is first processed into a cup shape with an upper opening and a lower closed portion by the drawing method, the surface and weight of each part may be uneven or slip in the thickness direction. The first probability that the earing phenomenon will occur (P ₁ ),
When a sheet laminated with BMB by atomic diffusion bonding is first processed into a cup shape with an upper opening and a lower closed portion by a drawing method, the BMB bonding boundary is formed by the atoms of each of the first single copper layer, mild steel layer, and second single copper layer. By suppressing layer slip, overall slip in the thickness direction is suppressed, and the relationship between the second probability (P ₂ ) of the earing phenomenon occurring even though mild steel has greater tensile strength and formability compared to single copper or brass, resulting in less structural change during drawing, is
0 ≤ P ₂ ＜ P ₁ ≤ 1
and
In the case of single-acting metal or brass metal, the possibility of earing phenomenon occurring due to non-uniformity of the surface and weight of each part or slip in the thickness direction is relatively high, whereas for BMB metal, the BMB joint interface is the first single-couple layer, mild By suppressing atomic layer slip in each of the steel layer and the second single-layer layer, slip in the overall thickness direction is suppressed,
Since the bonding interface between the single copper layer and the mild steel layer exhibits different interfacial characteristics from the atomic arrangement within the single copper layer or the atomic arrangement within the mild steel layer, the slip in the thickness direction inside the single copper layer is directly transmitted to the mild steel layer through the bonding interface. It cannot be done and is suppressed,
Mild steel has greater tensile strength and formability compared to single copper or brass, showing less structural change during drawing, so it can relatively lower the possibility of earing phenomenon.
When applied to tracer bullets, it prevents the heat generated when firing from being directly transferred to the tracer and prevents deformation of the warhead, allowing the trajectory of the bullet to be seen with the naked eye.
A single-mild steel-single copper (BMB) metal material for warhead cups to replace single copper and brass, where the combined thickness ratio of the first single layer and the second single layer is 10% to 20%. delete According to paragraph 1,
The specific gravity is reduced by more than 7% compared to brass metal material of the same volume and by more than 9% compared to single copper metal material,
The thickness ratio of the first single copper layer, the mild steel layer, and the second single copper layer is 5~7:80~90:5~15,
The weight ratio of the first single copper layer, the mild steel layer, and the second single copper layer is 5.5~7.7:78.1~88.9:5.5~16.4,
The weight ratio per square meter of the first single layer, mild steel layer, and second single layer is 0.4400~0.6160: 6.2800~7.0650: 0.44~1.32,
The weight ratio of Dandong to the total is 11.1~21.9%,
Mild steel reinforces the hardness of the single-acting material, making it harder than single-acting metal or brass metal of the same volume.
The thermal conductivity of mild steel is lower than that of single copper or brass, and the melting point of mild steel is higher than that of single copper or brass, so it has better heat resistance and lower thermal conductivity than single copper or brass metal materials of the same volume.
Single-to-mild steel-to-single brass (BMB) metal for warhead cups to replace single copper and brass, with a copper content lower than that of the same volume of single metal or brass metal.