SE2300041A1 - Wedge - Google Patents

Abstract

The present invention relates to a method for producing a wedge (1) for an ejection device, the method comprising that a raw material for the wedge (1) is additively manufactured from at least one metal powder, after a raw material for the wedge (1) has been manufactured, the raw material is post-treated for the production of the wedge (1) by exposing the raw material for the wedge to high pressure and heat, also referred to as Hot Isostatic Pressing, HIP, for pressing and sintering the metal powders contained in the raw material. The invention further relates to a wedge and an ejection device comprising a wedge.

Description

Filed with the Swedish Patent and Registration Office 2023 -Û5~ UH WEDGE FOR AN EXPANSION DEVICE AND METHOD FOR MANUFACTURING A WEDGE FOR AN EXPANSION DEVICE TECHNICAL FIELD The present invention relates to a method for manufacturing a wedge for an ejection device, where the method comprises that a raw material for a wedge is additively manufactured from at least one metal powder, after a raw material for a wedge has been manufactured, the raw material for manufacturing the wedge is post-treated by exposing the raw material for a wedge to high pressure and heat, also known as Hot Isostatic Pressing, HIP, for pressing and sintering the metal powders contained in the raw material. The invention further relates to a wedge and to an ejection device comprising a wedge.

BACKGROUND OF THE INVENTION, PROBLEM AND PRIOR ART Firing devices, such as gunpowder-based weapons, are fired by burning gunpowder and thereby creating a gas expansion where the gas expansion moves a projectile in a gun barrel. A wedge mechanism is a common mechanism for firing devices such as a cannon, especially automatic cannons. A central component of the wedge mechanism is an almost rectangular metal block, also called a wedge, which can slide in grooves in the firing device, the breech of the piece, perpendicular to the longitudinal axis of the gun barrel. By operating the wedge perpendicular to the gun barrel, an opening to the gun barrel chamber can be created so that an ammunition unit can be arranged in the chamber, after which the wedge can be operated so that it is arranged behind the ammunition unit and thereby locks the ammunition unit in the gun barrel, after which the ammunition unit can be fired. Preferably, a firing pin is arranged in the wedge which can strike a fuse arranged in the ammunition unit which initiates the propellant charge in the ammunition unit. The wedge design makes it possible to obtain a high rate of fire, but it is not gas-tight, which means that the propellant charge must be enclosed in a sleeve. When the piece is to be loaded, the wedge is moved to the side by hand or machine power and an ammunition unit is inserted into the chamber. In a common embodiment, the sleeve on the ammunition unit strikes ejectors which are arranged on both sides of the cartridge position/chamber and this releases a latch so that the wedge is closed. After the Inkom til! Patent and registration office 202.3 -05- US ammunition unit has been fired, the wedge mechanism is opened again, usually with the help of recoil force. The mechanism is designed so that the wedge presses the ejectors rearward as it slides away so that the empty case is ejected. The process can then be initiated again so that an automatic cannon can be provided which repeatedly, in sequence, fires ammunition units. Each ammunition unit is provided with a projectile and propellant arranged in a sleeve. In the sleeve an ignition device is arranged above it comprising a primer which can ignite the propellant charge. As an alternative to a primer, the propellant charge can be ignited with, for example, an electrical pulse or with a laser.

Examples of manufacturing methods for wedges or other breech components are given in patent document CN 110893503 A which describes a method for manufacturing components by additive manufacturing methods including arc welding.

Examples of manufacturing methods involving hot isostatic pressing are given in patent specification US 2020/0230699 A1 which describes a method for manufacturing hollow components using hot isostatic pressing.

The above prior art does not demonstrate that additive manufacturing methods involving powder for manufacturing wedges are used.

Further problems that the present invention aims to solve will become apparent in connection with the following detailed description of the various embodiments.

Filed with the Swedish Patent and Registration Office 2023 -05- US PURPOSE OF THE INVENTION AND ITS FEATURES The purpose of the present invention is to provide an improved method of additively manufacturing a wedge with high tolerance (near net shape) adapted to interact with other metal components included in the ejection device.

The invention relates to a method for producing a wedge for an ejection device, where the method comprises that a raw material for the wedge is additively manufactured from at least one metal powder, after a raw material for the wedge has been manufactured, the raw material is then treated for the production of the wedge by exposing the raw material for the wedge to high pressure and heat, also known as Hot Isostatic Pressing, HIP, for pressing and sintering the metal powders contained in the raw material.

According to further aspects of the method for producing a wedge according to the invention; that additive manufacturing comprises that metal powder is melted in a vacuum chamber by an electron beam. that additive manufacturing comprises that metal powder is distributed over a surface and melted by a laser beam. that further post-treatment, after Hot Isostatic Pressing, comprises heat treatment. that further post-treatment, after Hot Isostatic Pressing and heat treatment, comprises mechanical processing of the wedge. that raw material for the wedge is manufactured from two different metal powders, a surface material and a bulk material. that the surface material preferably consists of low-alloy NiCrMo steel.

Filed with the Swedish Patent and Trademark Office 2023 -05- US A low-alloy NiCrMo steel is characterized by high strength and high hardness. The high hardness is needed as a result of abrasion that occurs during firing and high strength to resist plastic deformation. Since the surface layer has such a high strength, properties such as ductility and toughness will be affected. Instead, the material will be somewhat brittle. Therefore, a tough core is needed, as in the bulk material, of a more alloyed steel, e.g. tool steel or martensitic stainless steel.

The low-alloy NiCrMo steel has a yield strength of minimum 1200 MPa and an impact strength at -40 C of minimum 27 J. The bulk material preferably consists of stainless steel or tool steel.

The stainless steel or tool steel has higher levels of Cr and Ni than the low-alloy carbon steel used on the surface. The core, the bulk material, should consist of a more low-alloy steel, e.g. a tool steel with higher levels of Cr and Ni than the low-alloy carbon steel used on the surface. A risk with HIP is that each grain in the metal before HIP can oxidize and then lead to a reduction in toughness and fatigue properties as the oxides of each grain lead to natural crack growth paths. Therefore, steels (stainless steels/tool steels) with higher levels of Chromium are used, which form chromium oxide and counteract this. The core material should be made of stainless steel or a tool steel and be characterized by properties such as good fatigue strength, toughness and ductility. Materials that can be used are, for example: Stainless martensitic steels; X4CrNiMo16-5-1 (1_4418), Super 13 Cr (UNS S41426) Tool steel: X40CrMoV5-The stainless steel or tool steel has a yield strength of approximately 800-900 MPa and an impact strength at - 40 C of minimum 50 J.

The invention further comprises a wedge.

The invention further comprises an ejection device comprising a wedge.

Filing to the Swedish Patent and Trade Mark Office 2023 -ÛS- [ADVANTAGES AND EFFECTS OF THE INVENTION By manufacturing parts of the wedge or the entire wedge through additive manufacturing, a wedge with higher strength and toughness can be achieved compared to current technology based on cutting processing of a forging blank. For future launch systems, where both the rate of fire and the forces acting on the wedge are expected to increase, new manufacturing solutions for the wedge are required to improve the properties of the wedge. LIST OF FIGURES The invention will be described in more detail below with reference to the attached figures where: Fig. 1 shows a wedge in cross-section, according to an embodiment of the invention.

Fig. 2 shows the method steps for manufacturing a wedge, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT The present invention shows embodiments of manufacturing methods for improved wedge for ejector.

A launcher, also called a cannon, howitzer, or piece, such as an automatic cannon, is intended to fire a projectile by means of a propellant. Preferably, a propellant, such as gunpowder, is initiated in a part of the cannon, often a chamber specially adapted for this. For the automatic cannon, the propellant is preferably arranged in a sleeve. Initiation takes place by igniting the propellant, for example with a primer or a igniter in an ammunition unit, which is initiated by impact. Other methods of igniting the propellant can be by laser or electrical energy igniting the propellant. The propellant burns at high speed and with a large amount of gas evolution, which creates a gas pressure in the chamber that drives the projectile out of the firing barrel of the launcher. The propellant is adapted to generate, to the greatest extent possible, a constant pressure on the projectile throughout the entire course of the barrel, as the projectile moves in the barrel, which creates a high velocity on the projectile when the projectile leaves the muzzle of the barrel. For automatic cannons arranged to fire ammunition units, the projectile, igniter and propellant are arranged in a sleeve. By arranging the propellant in a sleeve, a simpler mechanism, often referred to as a wedge, can be used to close behind the ammunition unit when the ammunition unit is arranged in the chamber of the barrel. The wedge does not close gas-tight to the barrel, which enables a high rate of fire, i.e. ammunition units can be replaced at high speed by opening the wedge and enabling an ammunition unit to be arranged to the barrel, then moving the wedge so that it closes to the barrel, after which the projectile is fired from the ammunition unit, after which the empty case is removed, and then again arranging an ammunition unit to the barrel.

Projectiles, such as various types of grenades, in most cases include some form of action part and some form of fuse that initiates the action part. Fuses can be of different types, where impact is common for projectiles that are intended to explode upon contact with an object, time fuses when the projectile is intended to explode at a certain predetermined time, and zone fuses when the projectile is intended to explode when an object comes within a certain distance of the projectile. Zone fuses are preferably used when fighting aircraft and usually for medium-caliber ammunition, such as 40 mm and 57 mm, while time fuses and impact can be used when fighting a large number of different objects. It is advantageous to combine different types of fuse function in the same fuse, so that if a fuse with a zone fuse function does not detect any object, the projectile explodes after a certain time, etc.

The action part preferably comprises some form of explosive and some form of fragmentation casing that encloses the explosive. Furthermore, various forms of control means, such as fins, can be arranged either in the fuse or in a separate sub-component.

In order to stabilize the projectiles after they have left the barrel, the projectiles are preferably provided with rotation alternatively with fins. In the case where the projectiles are provided with rotation, the projectiles are said to be rotation stabilized and in the case where the projectiles are provided with fins, the projectiles are said to be fin stabilized.

Fin-stabilized projectiles should have no or low rotation when they leave the barrel.

Submitted to the Swedish Patent and Registration Office 2023 -05-To achieve rotation on the projectiles, rifling is often arranged in the barrel to which the projectile connects during the ejection process. Rifling means that the barrel of a firearm, the barrel, is provided with spiral grooves. The opposite is a smooth-bore barrel. When the rifling engages the projectile during firing, the projectile is rotated along its longitudinal axis. Through the rotation, minor irregularities or damage to the projectile will not cause a drift in the projectile's trajectory. Rotation is also necessary for an oblong (torpedo-shaped) projectile to maintain its direction after it leaves the barrel and not start to tumble around, this is called the projectile being rotationally stabilized. In smooth-bore weapons, only round (spherical) projectiles or fin-stabilized projectiles can be fired. An oblong projectile without fins will tumble when it leaves the muzzle.

Thus, rifling is a groove in the barrel of a firearm, and the elevation between them is called a ridge. Usually, the rifling of small-caliber firearms consists of four right-handed ridges, while cannons, such as artillery pieces, have a larger number of ridges depending on the caliber of the firing device. In order for the rifling to engage the projectile, the projectile must either be slightly larger than the diameter between the ridges, which is common for small-caliber weapons, or be provided with a special flange, called a girdle, which has a slightly larger diameter than the ridges, which is common in projectiles with a diameter of greater than 20 mm. The girdle 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 rotates one full revolution is called the pitch and is usually given in inches per revolution. Most barrels include rifling and by arranging projectiles with sliding belts, both rotationally stabilized and fin-stabilized projectiles can be fired with rifled barrels. Smooth-bore barrels are in principle only used for weapon systems intended to combat armored combat vehicles, as the rotation of the projectile means that the directed explosive effect, RSV, works less well because centrifugal force spreads the jet out.

If the wedge, or other parts of the launching system, are manufactured using HIP, materials with high resistance to shock loads can be achieved. Shock loads are part of the recoil forces that arise in a launching system when projectiles are fired from a gun barrel. It is desirable to achieve a wedge with higher strength and toughness compared to current technology. Since the wedge is part of the mechanism in a launching system, material compatibility between the components in the launching system is assumed. For example, if the wedge is changed to a different material than the other components in the launching system, there is a risk that corrosion may occur, for example if the nobleness varies between the components in the launching system. In particular, there are risks of corrosion for pieces in a marine environment when a conductive liquid, such as salt water, can act as a conductive liquid that can cause galvanic corrosion of the components included in the piece if the material/nobility between the components differs. It is therefore relevant that the surface of the improved wedge has similar material properties as the surrounding components in the launch system as the wedge will be located close to other components in the launch system and also be exposed to salt water.

By additive manufacturing a wedge where the additively manufactured wedge undergoes hot isostatic pressing, an improved wedge can be achieved. Preferably, a wedge is additively created with a specific material but can also be manufactured from two materials, one material in the core and one material in the surface layer. The additively manufactured component undergoes Hot Isostatic Pressing to eliminate pores in the part.

The raw material for the wedge is manufactured additively, preferably with 3D Printing, as the outer geometry of the wedge is too complex to manufacture as is usually done with HIP, i.e. pressing of sheet metal and welding. Additive manufacturing of the wedge means that a wedge with great precision can be manufactured, which means that subsequent machining can be avoided or reduced. The process is called manufacturing according to Near Net Shape, NNS. After the raw material for the wedge has been additively manufactured, the HIP process is started with evacuation and vibration. Hence HIP in an oven.

Hot Isostatic Pressing, HIP, is a manufacturing process for controlling grain size and structure in the material. HIP also enables the compaction of metal, polymer, ceramic and composite powders into a solid form. The advantages include that all internal voids in metal components created by additive manufacturing methods are removed and that mechanical properties, such as Inkom to Patent and Registration Office 2023 -ÛE-fatigue resistance/fatigue strength, toughness, plasticity and impact strength, are improved. Furthermore, HIP can create a dense material from metal, composite, polymer or ceramic powders without melting and that materials with partly different characteristics can be coordinated in the same component.

With HIP, a solid material with superior properties can be created from powder as the powder/powder components have a fine, uniform grain size and isotropic structure. Furthermore, by using HIP, different metals can be joined without the need for temperature-limiting adhesives. With HIP, multiple diffusion bonds can be achieved 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, intermetallics and polymers. HIP enables the bonding and combinations of materials that cannot otherwise be combined, i.e. composites.

After the raw material for the wedge has undergone hot isostatic pressing, various forms of heat treatment can be carried out to change the mechanical properties of the wedge. After heat treatment, if necessary, fine machining can be carried out such as cutting or grinding the part to adapt the part based on adaptation to the ejection system. Additive manufacturing, such as various forms of 3D printing, can be carried out where one material is selected for a surface layer and another material is selected for the core, the bulk material.

In a first embodiment, the raw material for the wedge is additively manufactured from a material. The material consists of a low-alloy steel, medium-alloy steel or a stainless steel. Medium-alloy and stainless steel reduce the risk of the grains that make up the metal powder oxidizing before the additive manufacturing and hip and then provide better toughness and fracture toughness properties. Examples of medium-alloy and stainless steel are metals alloyed with at least 5% Cr. Chromium prevents the grains from oxidizing as chromium forms chromium oxide when in contact with air. For example, from low-alloy NiCrMo carbon steel, i.e. a steel with a lower proportion of alloying elements, with the same or similar chemical composition as adjacent parts (breech and barrel). By choosing a steel grade with similar properties as other parts of the firing system Filed to the Patent and Registration Office 2023 -05-, good material compatibility can be achieved. It is important to avoid oxides on the particles/grains in the metal powder as oxides create natural paths for cracks to propagate. Build direction is also important in additive manufacturing as the structure of the metal is controlled by this. It also leads to the material becoming anisotropic, i.e. different properties in different directions. Correspondingly the same as for forging and drawing direction.

In a second embodiment, the raw material for the wedge is additively manufactured from two materials, a first material in the surface layer and another material in the core, the bulk material. The material for the surface layer preferably consists of low-alloy NiCrMo carbon steel, i.e. a steel with a lower proportion of alloying elements, with the same or similar chemical composition as adjacent parts (breech and barrel). By choosing a steel grade with similar properties as the other parts of the firing system, good material compatibility can be achieved. The core, the bulk material, can then consist of another material with other properties adapted to better withstand the forces acting on the wedge from recoil.

A number of different methods for additive manufacturing are considered relevant, such as - Electron Beam Melting (EBM) - Direct Laser Metal Sintering (DMLS).

With Electron Beam Melting, EBM, the part is manufactured layer by layer in a vacuum chamber and uses an electron beam to melt metal powder that is fed from a holder/cassette, and distributed/spread on a platform/coordinate table. The electron beam then heats the metal powder and melts the metal powder to complete a part, also called a blank. Relatively high temperatures are created by the electron beam, which melts the metal powder in the focus point of the electron beam. By distributing the material/melting the material based on a CAD model, a part with great freedom in terms of geometric structure can be created, and several metal powders can be used to create a part consisting of several different materials. The part is built layer by layer.

With Direct Metal Laser Sintering, DMLS, the part, also known as the raw material, is manufactured by heating one or more different powder materials and spreading them out in an even layer over a platform/coordinate table with a roller, after which a pulsed laser irradiates selected parts of the powder material where a cross section can be created by the powder particles, through the heat generated by the laser, adhering to each other and forming a part. The layer thickness is 0.1 mm and powder that does not become part of the part can be reused.

By the additively manufactured component undergoing HIP, pores/inclusions/other defects that are present in an additively manufactured part will be sealed or closed. The additive manufacturing, 3D printing, is preferably carried out in a vacuum in a vacuum chamber or in a pressure chamber with an added protective gas, which means that compression during hot isostatic pressing, HIP, is possible. In the case that the additive manufacturing would take place at atmospheric pressure in air, hot isostatic pressing can result in pores not being closed in a desirable way as the air cannot be compressed in the same way as for a part manufactured in a vacuum or in a pressure chamber with an added protective gas.

In Fig. 1 a wedge 1 is shown in cross-section where the wedge has a surface material 10 and a bulk material 20. In a first embodiment, the surface material 10 and the bulk material 20 are the same material. In a second embodiment, the bulk material 20 and the surface material 10 are of different types, where the bulk material 20 is preferably of stainless powder steel such as a martensitic steel and the surface material 10 is preferably of low-alloy carbon steel. The bulk material 20 preferably has material properties that result in high toughness and maintained or slightly lower strength when the stresses are highest in the surface. The contact surface between the bulk material 20 and the surface capsule 10 is a diffusion bond that is created by Hot Isostatic Pressing of the powder component/raw material. The additively manufactured component, the raw material, is arranged in an oven preferably arranged with a connection device for evacuating air, vacuum pumping, before and/or during the implementation of the manufacturing method before Hot Isostatic Pressing.

Fig. 2 shows a manufacturing method 100 for wedge 1 using HIP. Initially, a wedge blank is additively manufactured from at least a first metal powder in the step Wedge blank is additively manufactured from at least one metal powder 102. In an alternative embodiment, one metal powder is used for the surface coating of the wedge blank and another metal powder is used for the bulk material, the core, of the wedge blank. The raw material for the wedge is manufactured from powder using an additive manufacturing method, such as EBM or DMLS, but other currently available methods, and any future additive manufacturing methods, can also be used to manufacture the raw material for the wedge. In the Evacuation, vibration, sealing step 103, the raw material for the wedge can be prepared for the next step HIP. In the case that the raw material is manufactured completely additively, step 103 can be omitted so that the raw material is already prepared for HIP. Thereafter, hot isostatic pressing is carried out in the HIP step 104, i.e. a gas is used to create an isostatic pressure on the raw material by arranging the gas to a connection device on the furnace. Before the gas is arranged on the furnace, the furnace can be vacuum-pumped or otherwise evacuated with air or the filling gas/fluid that is arranged in the furnace before evacuation, for example by flushing with a noble gas. The entire blank is then heated to create a preform or HIPPAD 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). After hot isostatic pressing has been carried out, the body can undergo heat treatment/hardening 106, which means that the now joined body is heated. After heat treatment, the material is suitable for processing, for example cutting processing in the Processing step 108 where cutting processing such as turning or milling or grinding. In some cases, a Surface Treatment 110 such as phosphating or manganese phosphating is also carried out as rust protection.

ALTERNATIVE EMBODIMENTS The invention is not limited to the embodiments specifically shown but can be varied in various ways within the scope of the claims.

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

Furthermore, all forms of wedges and end pieces for both small caliber, medium caliber and large caliber are included.

Claims (1)

1. Method for producing a wedge (1) for an ejection device, characterized in that the method comprises that a raw material for the wedge (1) is additively manufactured from two different metal powders, a surface material and a bulk material, after a raw material for the wedge (1) has been manufactured, the raw material is post-treated for the production of the wedge (1) by subjecting the raw material for the wedge to high pressure and heat, also referred to as Hot Isostatic Pressing, HIP, for pressing and sintering the metal powders contained in the raw material. Method according to claim 1, characterized in that additive manufacturing comprises that metal powder is melted in a vacuum chamber by an electron beam. Method according to claim 1, characterized in that additive manufacturing comprises that metal powder is distributed over a surface and melted by a laser beam. Method according to any of the above claims, characterized in that post-treatment further, after Hot Isostatic Pressing, comprises heat treatment. Method according to claim 4, characterized in that further post-treatment, after Hot Isostatic Pressing and heat treatment, comprises mechanical processing of the wedge. Method according to any of the above claims, characterized in that the surface material preferably consists of low-alloy NiCrMo steel. Method according to any of the above claims, characterized in that the bulk material preferably consists of stainless steel or tool steel. Wedge (1) with high tolerance adapted to cooperate with other metal components included in the ejection device manufactured according to any of claims 1 - Ejection device arranged with a wedge according to claim 8.