Barrel and method for manufacturing a barrel

Abstract

The present invention relates to a method for manufacturing barrels or barrel segments, wherein the method comprises arranging a liner comprising a groove arranged with grooves, and wherein at least two rings are arranged surrounding the liner to complete a barrel or a barrel segment. Furthermore, the invention relates to a method for manufacturing barrel, barrel, and ejection devices.

Description

[0001] BARREL AND METHOD FOR MANUFACTURING A BARREL AND

[0002] EJECTION DEVICE INCLUDING A BARREL

[0003] TECHNICAL FIELD

[0004] The present invention relates to a method for manufacturing a barrel or barrel segment, wherein the method comprises arranging a liner comprising a groove arranged with grooves, and wherein at least two rings are arranged surrounding the liner to complete a barrel or a barrel segment. Furthermore, the invention relates to a method for manufacturing barrels, barrels, and ejection devices arranged with barrels.

[0005] BACKGROUND OF THE INVENTION, PROBLEM STATEMENT AND KNOWN TECHNOLOGY

[0006] Firearm-based weapons are fired by burning gunpowder, thereby creating a gas expansion which propels a projectile in a barrel. Barrels equipped with rifling are preferably equipped with rifling with a pitch over the length of the barrel, which causes the projectile to rotate during the ejection process. Rotation of the projectile is desirable in order to achieve a rotationally stabilized projectile, i.e. the projectile rotates after it has left the barrel. As an alternative to a rotationally stabilized projectile, the projectile can be stabilized with, for example, fins. In this case, it may be desirable for the projectile not to rotate when it leaves the barrel, which is why the projectile in this case can be designed with a sliding obturator or driving band, which means that the projectile does not, or only to a certain extent, rotate during the ejection phase of the projectile when the projectile is fired from a rifled barrel. When the projectile leaves the barrel in this case, it is stabilized by fins arranged on the projectile. Alternatively, the projectile can be fired from a barrel without grooves, also known as a smoothbore barrel, which means that no rotational force is transferred to the projectile during the launch process.

[0007] Conventionally, barrels are manufactured by cutting a forged material. These manufacturing methods are costly and time-consuming and result in a barrel that is adapted to manufacturing limitations rather than functional requirements, often resulting in a relatively heavy barrel.

[0008] Conventional grooving of barrels involves several steps of cutting, including drilling, turning, honing and grooving with specially adapted equipment, which is not only costly but also limits the possibilities for changing the design of the grooves.

[0009] An example of a manufacturing method for grooved barrels is given in patent specification EP 0 339 692 A2, which describes a method for manufacturing a barrel in which an inner template is manufactured on which layers of refractory material in powder form are arranged.

[0010] An example of a manufacturing method for manufacturing barrels with a liner with an inner material and an outer material is given in patent specification US 4,747,225 A, which describes a method for manufacturing a barrel in which an inner liner is manufactured from metal powder arranged in a surrounding steel tube.

[0011] The above-mentioned known technology does not demonstrate that a liner arranged with grooves can be reinforced by arranging an additional segmented structure.

[0012] Further problems that the present invention aims to solve are apparent in connection with the following detailed description of the various embodiments.

[0013] PURPOSE OF THE INVENTION AND ITS CHARACTERISTICS

[0014] The purpose of the present invention is to provide an improved method for manufacturing an improved barrel with the possibility of adapting the weight, length, and the design of the rifling based on the technical requirements of the barrel and not based on manufacturing limitations.

[0015] The invention relates to a method for manufacturing barrel or barrel segments, wherein the method comprises the steps of: i.) a liner comprising a bore arranged with grooves is arranged, ii.) at least two rings are arranged to enclose the liner to complete a barrel or barrel segment.

[0016] According to further aspects of the method for producing barrel or barrel segments according to the invention, the following applies: t h e material thickness of the rings varies along the length of the barrel so that the rings with the greatest material thickness are arranged near the chamber and the rings with the least material thickness are arranged near the muzzle of the barrel. t h e liner comprising grooves is cooled before the rings are arranged on the liner. t h e rings are heated before the rings are arranged on the liner. t h e liner is manufactured by: i.) a capsule structure is arranged surrounding a template core, ii.) powder is arranged in the cavity between the capsule structure and the template core, where the template core is wholly or partly arranged with grooves for embossing a groove pattern on the liner, iii.) the powder is pressed using high pressure and heat, also known as hot isostatic pressing, HIP, so that the powder and capsule structure are joined together, iv.) the template core is removed for the production of a liner. t h e template core is provided with a foil or powder coating before the template core is arranged in the capsule construction. t h e liner is heat treated and hardened after hot isostatic pressing to complete a liner.

[0017] The invention further comprises a barrel.

[0018] The invention further comprises an ejection device comprising a barrel.

[0019] ADVANTAGES AND EFFECTS OF THE INVENTION

[0020] By manufacturing barrels by arranging rings on a liner manufactured with HIP with a template core, also known as mold core, an improved barrel can be manufactured with reduced weight, which results in improved barrel performance as the deformation of the barrel due to its own weight is reduced or completely avoided. Furthermore, grooving of the barrel can be performed in a simpler manner and with greater freedom to choose the grooving design compared to current manufacturing methods for grooving the barrel. Furthermore, better material performance can be achieved with regards to the inner jacket surface of the barrel, as a barrel manufactured with a liner arranged with rings is autofrettaged, i.e. the inner jacket surface is plastified locally to obtain a compressive stress state that counteracts crack growth in the inner jacket surface of the barrel.

[0021] LIST OF FIGURES

[0022] The invention will be described in more detail below with reference to the accompanying figures, where:

[0023] Fig. 1 shows a schematic diagram of the manufacture of barrel segments, according to one embodiment of the invention. Fig. 2a shows a capsule construction according to one embodiment of the invention.

[0024] Fig. 2b shows a cross-section of a capsule construction according to one embodiment of the invention.

[0025] Fig. 3 shows a barrel, according to one embodiment of the invention.

[0026] Fig. 4 shows the process steps for Hot Isostatic Pressing, HIP, in the manufacture of a liner, according to one embodiment of the invention.

[0027] Fig. 5 shows the process steps for manufacturing a barrel from a liner, according to one embodiment of the invention.

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention discloses embodiments of manufacturing methods for barrel and / or components for barrel, such as barrel segments.

[0030] A projectile device, also referred to as a cannon, howitzer, or gun, such as an artillery gun, is intended to fire a projectile using a propellant. Preferably, a propellant, such as gunpowder, is ignited in a part of the cannon, often a chamber specially adapted for this purpose. Ignition occurs through the ignition of the propellant, for example with a primer or a detonator in an ammunition unit, which is initiated by impact. Other methods of igniting the propellant include laser or electrical energy. The propellant burns at high speed and generates a large amount of gas, which creates gas pressure in the chamber that drives the projectile out of the barrel of the firing device. The propellant is designed to generate as constant pressure as possible on the projectile throughout the entire barrel, as the projectile moves through the barrel, creating a high velocity for the projectile as it leaves the muzzle.

[0031] Projectiles, such as various types of grenades, in most cases include some form of warhead and some form of fuze that initiates the warhead. Fuzes can be of various types, with impact fuzes being common for projectiles that are intended to detonate upon contact with an object, time fuzes when the projectile is intended to detonate at a predetermined time, and proximity fuzes when the projectile is intended to detonate when an object comes within a certain distance of the projectile. Proximity fuzes are primarily used in the combat of aircraft and usually for medium-calibre ammunition, such as 40 mm and 57 mm, while time fuzes and impact fuzes can be used in the combat of a large number of different objects. It is advantageous to combine different types of fuze functions in the same fuze, so that if a fuze with a zone fuze function does not detect any object, the projectile detonates after a certain time, etc.

[0032] The warhead preferably comprises some form of explosive and some form of splinter-acting casing that encloses the explosive. Furthermore, various forms of control devices, such as fins, can be arranged in the fuze or in a separate subcomponent.

[0033] In order to stabilize the projectiles after they have left the barrel, the projectiles are preferably designed with rotation or fins. In the case where the projectiles are designed with rotation, the projectiles are said to be rotationally stabilized, and in the case where the projectiles are designed with fins, the projectiles are said to be fin- stabilized. Fin-stabilized projectiles should not have rotation or low rotation when they leave the barrel.

[0034] To achieve rotation of the projectiles, grooves are preferably arranged in the barrel to which the projectile mechanically connects during the ejection process. Rifling means that the barrel of a firearm, the barrel, is provided with spiral grooves. The opposite is a smoothbore barrel. When the grooves in the barrel engage with the projectile during firing, the projectile rotates along its longitudinal axis. The rotation prevents minor irregularities or damage to the projectile from causing a deviation in its trajectory. Rotation is also necessary for an oblong (torpedo-shaped) projectile to maintain its direction after leaving the barrel and not start tumbling around; this is referred to as the projectile being rotationally stabilized. Only round (spherical) projectiles or fin-stabilized projectiles can be fired from smoothbore weapons. An elongated projectile without fins will tumble when it leaves the muzzle. Rifling is thus grooves arranged in the barrel of the firearm, and the elevation between the grooves is called lands. Usually, the rifling in small-calibre handguns consists of four right-handed grooves, while cannons, such as artillery pieces, have a larger number of grooves depending on the calibre of the launching device. In order for the rifling to engage the projectile, the projectile must either be slightly larger than the diameter between the grooves, which is common for small-calibre weapons, or be equipped with a special flange, called a driving band, which has a slightly larger diameter than the grooves, which is common in projectiles with a diameter greater than 20 mm. The driving band can be made of plastic, composite material or a soft metal, such as copper or a copper alloy. The length of the barrel over which the rifling turns a full turn is called the pitch and is usually specified in inches per turn.

[0035] Most barrels include rifling, and by designing projectiles with slipping bands, both rotation-stabilized and fin-stabilized projectiles can be fired with rifled barrels. Smoothbore barrels are used almost exclusively for weapon systems designed to combat armored combat vehicles, as the rotation of the projectile causes the directed blast effect (RSV) to be less effective because the centrifugal force causes the beam to spread out.

[0036] Hot isostatic pressing (HIP) is a manufacturing process for controlling grain size and structure in materials. HIP also enables metal, polymer, ceramic and composite powders to be compacted into a solid form. The advantages include the removal of all internal voids in metal components created by additive manufacturing methods and the improvement of mechanical properties such as fatigue resistance / fatigue strength, toughness, plasticity and impact strength. Furthermore, HIP can produce a dense material from metal, composite, polymer or ceramic powders without melting, and materials with partially different characteristics can be combined in the same component.

[0037] With HIP, a solid material with superior properties can be created from powder, as powder / powder components have a fine, uniform grain size and isotropic structure. Furthermore, by utilizing HIP, different metals can be joined without the need for temperature-limiting binders. HIP can be used to achieve multiple diffusion bonds in a single process cycle. HIP works for a large number of metal alloys, as well as polymers and ceramic materials. For example, alloys with nickel, cobalt, tungsten, titanium, molybdenum, aluminum, copper and iron, oxide and nitride ceramics, glass, intermetallic substances and polymers. HIP enables the bonding and combinations of materials that cannot otherwise be combined, i.e. composites. An example of a suitable material is the combination of tungsten carbide and iron.

[0038] Fig. 1 shows a schematic diagram of the manufacture of a liner 1 for a barrel or barrel segment, in which a template core 20 is arranged in an outer tube 11, which is part of a capsule structure, so that a void, a cavity 30, is arranged between the capsule structure and the template core 20. The template core 20 may be arranged with a foil 23 that rests on the outer surface of the template core and is arranged to follow the grooving pattern of the template core, or a powder with desirable properties may be arranged against the template core. Powder can be arranged in cavity 30 to manufacture a liner 1 using HIP. Liner 1 can be designed in one piece for the completion of a complete barrel but can also consist of components that can be assembled to complete a complete barrel. Template core 20 is preferably arranged with a first part for manufacturing rifling in barrel segment 1 and also a second part where, for example, the chamber or other part for arranging a projectile / ammunition unit can be arranged. The second part is preferably not rifled. The template core is preferably made of metal but can also be made of other materials suitable for the continued method of manufacturing the liner. A foil, also referred to as film, can be arranged on the template core 20. The foil is arranged on the template core in such a way that the foil is stretched and without air pockets, which means that the foil is alloyed in an advantageous manner during hot isostatic pressing of the barrel and / or barrel components. The foil is preferably made with a thickness exceeding 100 nm and with a width that facilitates the arrangement of the foil on the mandrel, preferably the width exceeding 200 mm. In one embodiment, tantalum foil is used, but other materials can also be used. To facilitate the tantalum foil adhering to the template core, and in cases where several layers of tantalum foil are wound on the template core, the template core / foil can be treated with an adhesive substance that facilitates the tantalum foil adhering to the template core when the foil is arranged / wound on the template core. Furthermore, the tantalum foil can be arranged against the template core in a vacuum chamber, which means that the tantalum foil can be arranged against the template core without air pockets forming. Fig. 2a shows a view of a HIP container in the form of a capsule structure 10 for manufacturing a component for a barrel. The HIP container 10 is arranged with connection devices 12, 14 for evacuating air, vacuum pumping, before and / or during the implementation of the manufacturing method, as well as a front bottom plate 16 and an outer tube 11.

[0039] Fig. 2b shows a cross-sectional view of a HIP container in the form of a capsule structure 10 for manufacturing a component for a barrel. The HIP container 10 is equipped with connection devices 12, 14 for evacuating air and vacuum pumping before and / or during the manufacturing process, as well as a front base plate 16, a rear base plate 18 and an outer tube 11. The powder is freely arranged in the HIP container in the form of the capsule construction 10 between the capsule construction 10 and, if necessary, a foil 23 arranged on the template core 20. Through continued treatment in accordance with HIP, the powder is fixed in the intended place for the production of a liner 1. The material is applicable in powder form inside a HIP container in the form of capsule construction 10, which is an enclosing component arranged to retain powder, where powder, in the form of applied material, is arranged in capsule construction 10. Through continued treatment in accordance with HIP, the powder is fixed in the intended location for the production of a liner 1. Manufacturing methods involving powder have advantages in confined manufacturing conditions, as the material being supplied must reach into spaces with small dimensions. Examples of suitable materials are the combination of tungsten carbide powder and iron powder, as well as an additional structure of steel powder. The capsule construction 10 is arranged with a connection device for evacuating air and vacuum pumping, before and / or during the implementation of the manufacturing method. Several different types of metal powder can be arranged in the capsule construction in different positions to improve the functionality of the barrel tube component. The capsule construction 10 is preferably made of a material that a person skilled in the art would recognize as suitable for the purpose. In one embodiment, the material of the capsule structure 10 is black plate, in another embodiment the material is stainless steel, which also contributes to a rust-protective function for liner 1. The subcomponents of the capsule structure can also be manufactured additively. Fig. 3 shows a barrel 60 made of a liner 1 arranged with rings 3, 3'. Fig. 3 shows two rings 3, 3', but in a first embodiment, a large number of rings are arranged along the length of liner 1. The first part of liner 1 is arranged with chambers (not shown in the figure) and placed where the barrel is arranged against the ejection device and where the projectile is arranged for ejection in the barrel 60. Liner 1 is arranged with a number of rings 3 up to the muzzle 4 of the barrel. A liner 1 is manufactured using the above-mentioned manufacturing method and arranged with rings 3 by heating the rings 3 and thereby expanding them to a state in which the rings 3 can be arranged on liner 3. Alternatively, liner 1 can be cooled and then the rings 3 can be arranged on liner 3. Furthermore, a combination of heating the rings 3 and cooling the liner 1 can be carried out, after which the rings are arranged on the liner 1. After the rings 3 are arranged on the liner 1, the barrel 60, which consists of the liner 1 arranged with the rings 3, can cool so that the rings 3 contract, thereby producing a complete barrel 60 comprising a liner 1 with rings 3 fixedly arranged around the liner 1. When a certain compressive stress is applied to liner 1 by the cooling rings 3, autofrettage is achieved on the inner surface of the barrel, which results in improved resistance to crack propagation and / or crack formation. In the event that liner 1 is cooled and rings 3 are mounted on the cooled, and thus slightly shrunk, liner 1, liner 1 will expand out to the rings and thus achieve autofrettage on the inner surface of the barrel, which results in improved resistance to crack propagation and / or crack formation. Rings could be made of steel, for example, but can also be made of aluminum and / or composite or other materials. The size and design of the rings can be adapted along the length of the barrel. For example, the forces near the chamber may be greater, which may mean that the rings are designed with a thicker wall thickness near the chamber, and similarly, the forces are less near the muzzle, which may mean that the wall thickness of the rings decreases closer to the muzzle.

[0040] Fig. 4 shows manufacturing method 100 for liner 1 with HIP. Outer tube 11, rear bottom plate 18 and front bottom plate 16 are arranged together to create a capsule structure 10 in the step Designing a capsule structure 102. A template core 20 is also arranged in the capsule structure 10. A capsule structure 10, also referred to as a HIP container, is a device in which powder is arranged to deform the powder into a HIPED body under high temperature and high pressure. Powder in the capsule construction 10 is arranged in the step Powder is arranged in the capsule construction 104 by arranging powder between the template core 20 and the outer tube 11. The template core 20 can be centred in the outer tube 11 by arranging the template core 20 to the rear bottom plate 18 and the front bottom plate 16. After the powder material has been arranged in the capsule structure 10, it is evacuated, vibrated and sealed in the capsule structure 10 to distribute the powder evenly in the capsule structure 10 in the Evacuation, vibration and sealing of the capsule structure 106 step. Hot isostatic pressing is then performed in step HIP 108, i.e. a gas is used to create isostatic pressure on the capsule structure 10 by arranging the gas to a connection device arranged on the capsule structure 60. Before the gas is arranged to the capsule structure, the capsule structure can be vacuum-pumped or otherwise evacuated of air or the filling gas / fluid arranged in the capsule structure 10 before evacuation, for example by flushing with a noble gas. The entire capsule structure 10 is then heated to create a preform or HIP body. The HIP temperature is preferably 20% below the melting temperature of the material; for martensitic stainless steels, the HIP temperature is above the phase transformation to the austenitic state (which is in the order of 80% of the melting point of the material). Any foil arranged on the template core 20 is joined in the HIP 108 step with the powder arranged in the capsule structure. After hot isostatic pressing has been carried out, the body can undergo Heat treatment / hardening 110, which means that the now joined body is heated up. After heat treatment, the material is suitable for machining, for example cutting machining, so that excess material, for example material covering the opening for the outgoing passage for gas flow and possibly parts of the HIP container, is machined away in the Machining / pickling step 112, where cutting machining such as turning or milling, but also pickling or other chemical treatment such as treatment with acid, can be performed. The template core 20 is preferably removed by a combination of mechanical machining, such as tuming / drilling, and pickling, so that the grooving performed in the barrel tube segment is revealed. Where applicable, Surface treatment 114 is also performed. The material used as powder is preferably tungsten carbide, iron or tool steel or martensitic stainless steel with high concentrations of chromium and nickel, possibly with refractory material arranged on the surface of the muzzle brake to better resist erosion from gunpowder gases or powder specially adapted for the device against the foil arranged on the template core 20 in the event that a foil is used. Fig. 5 shows manufacturing method 200 for manufacturing barrel 60 from at least one liner 1 by arranging rings 3 on liner 1. Initially, rings 3 are heated in the step Heating of rings 202. When rings 3 are heated, they expand, which means that rings 3 can be arranged on liner 1. In the step Arranging rings on liner 204, one or more rings 3, preferably several rings 3, are arranged on liner 1. After the rings have been arranged on the liner, the barrel can be cooled, which takes place in the step Cooling of barrel 206. When the liner arranged with rings has been cooled, a complete barrel 60 is finished, which can then be arranged in an ejection device. In an alternative manufacturing method, the liner can be cooled after the rings have been arranged on the liner, or alternatively, the rings can be heated and the liner cooled after the rings have been arranged on the liner. After arranging the rings on the liner, the barrel can be cooled, which takes place in step 206, Cooling of barrel. When the barrel, consisting of a liner arranged with rings, is cooled, a complete barrel 60 is finished. To finish the barrel for arrangement on an ejection device, additional steps may be taken, such as various forms of heat treatment, which takes place in step Heat treatment / hardening 208. Further processing, for example to enable the barrel to be arranged on an ejection device, takes place in the Machining step 210. As a final step, the barrel can be surface treated to adapt the barrel to the system to which the barrel is arranged, which takes place in the Surface treatment step 212.

[0041] ALTERNATIVE EMBODIMENTS

[0042] The invention is not limited to the specifically shown embodiments, but can be varied in various ways within the scope of the patent claims.

[0043] It is understood, for example, that the choice of materials, the choice of geometric shapes, the elements and details included in the barrel or barrel components are adapted to the weapon system(s), platform and other design characteristics currently available.

[0044] Furthermore, all forms of barrel and barrel components for small calibre, medium calibre and large calibre weapons are included.

Claims

PATENT CLAIMS1. Method for manufacturing a barrel or barrel segment, characterised in that the method comprises the steps of:1.) a liner (1) comprising a rifled bore is provided, ii.) at least two rings (3) are arranged to enclose the liner to complete a barrel or a barrel segment, wherein the wall thickness of the rings (3) varies along the length of the barrel in the longitudinal direction so that the rings (3) with the greatest wall thickness are arranged near the chamber and the rings (3) with the least wall thickness are arranged near the muzzle (4).

2. Method according to claim 1, characterised in that the liner (1) comprising grooves is cooled before the rings (3) are arranged on the liner (1).

3. Method according to any of requirements 1-2, characterised in that the rings (3) are heated before the rings (3) are arranged on the liner (1).

4. Method according to any of claims 1-3, characterised in that the liner (1) is manufactured by: i.) a capsule structure (10) is arranged surrounding a template core (20), ii.) powder is arranged in the cavity between the capsule structure (10) and the template core (20), where the template core (20) is wholly or partly arranged with grooves for embossing a groove pattern on the liner (1), iii.) the powder is pressed using high pressure and heat, also known as hot isostatic pressing, HIP, so that the powder and capsule structure are joined together, iv.) the template core (20) is removed for the production of the liner (1).

5. Method according to claim 4, characterised in that the template core (20) is provided with a foil or powder coating before the template core is arranged in the capsule structure (10).

6. Method according to any of claims 4-5, characterised in that the liner (1) is heat treated and hardened after hot isostatic pressing to complete a liner (1).

7. Barrel (60) manufactured according to any of requirements 1-6.

8. Ejection device arranged with a barrel according to claim 7.

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