Projectile with driving band and method of manufacture of driving band

Abstract

The invention relates to a method of manufacturing a driving band (100) for a projectile, wherein the driving band (1) is manufactured from a coated carrier (2) comprising the following method steps: i.) a carrier (2) in the form of a tube having an inner surface and an outer surface is arranged, ii.) the inner surface of the carrier (2) is arranged with a fixing formation, iii.) the outer surface of the carrier is arranged with a bonding formation, iv.) a driving band material is deposited on the outer surface of the carrier (2), v.) the driving band (2) in the form of the carrier (2) with deposited material (3), is arranged for mounting on a projectile body. The invention further comprises a projectile body arranged with a driving band and a projectile.

Description

[0001] PROJECTILE WITH DRIVING BAND AND METHOD OF MANUFACTURE OF DRIVING BAND

[0002] TECHNICAL AREA

[0003] The present invention relates to a method of manufacturing a driving band for a projectile, wherein the driving band is made of a coated carrier. The invention further relates to a projectile body provided with a driving band and a projectile.

[0004] THE BACKGROUND, PROBLEM AND PRIOR ART OF THE INVENTION

[0005] Driving bands are used on projectiles fired from barrels to provide both a gas seal between the projectile and the barrel and a good frictional coupling with the barrel. Preferably, projectiles are rotationally stabilized to achieve better aerodynamic properties by causing the projectile to rotate during the ejection process as a result of a rifling performed in the barrel. When the projectile equipped with a driving band is ejected from the barrel, the driving band is partially deformed by the groove and thus the driving band grips the groove and rotates the projectile with the pitch of the groove. If a steerable projectile is desired, it is advisable that the projectile does not rotate as fins are unfolded and used to stabilize the projectile instead. Since it is desirable to use the same barrel and thus ejection device for all projectiles, the steerable projectiles are made with a sliding driving band and can thus be fired from a rifled barrel.

[0006] For projectiles that are to be rotationally stabilized, it is important that the driving band is fixed to the projectile so that the driving band does not rotate relative to the projectile and that the barrel groove deforms the driving band without the driving band rotating relative to the barrel rifle s / groove. It is also important that the driving band is arranged on the projectile in such a way that the projectile, the shell body, is not damaged or otherwise affected by the mounting of the driving band on the projectile.

[0007] Patent document US 1,299,013 discloses a driving band which is arranged to a projectile with a threaded joint. The driving band is made in one piece and does not include material composition that is optimal for strength and adaptation to the barrel. Patent document US 2,922,368 discloses a driving band which is arranged to a projectile with a groove joint. The driving band is made in one piece and does not include material composition that is optimal for strength and adaptation to the barrel.

[0008] For projectiles that are to be rotationally stabilized, a driving band of a soft metal is often provided with melt deposition which negatively affects the material properties of the projectile. The use of soft metal driving bands can also lead to barrel contamination as material from previously ejected driving bands becomes trapped in the barrel with negative consequences for the performance of the barrel.

[0009] Further problems that the present invention is intended to solve will be apparent from the following detailed description of the various embodiments.

[0010] THE PURPOSE OF THE INVENTION AND ITS CHARACTERISTICS

[0011] By manufacturing the driving band by coating a carrier in the form of a tube that is then arranged on the projectile, problems related to material weakening in the projectile body can be minimized or completely avoided. Furthermore, the use of customized materials in the coating can avoid previously known problems with barrel contamination. For conventional barrels, metal residues from the driving band from previously fired projectiles can adhere to the barrel and thus cause performance degradation.

[0012] Furthermore, a manufacturing method involving coated tubes is cheaper than previously known methods.

[0013] The invention is a method of manufacturing a driving band for a projectile, wherein the driving band is manufactured from a coated carrier according to the following method steps: i.) a carrier in the form of a tube having an inner surface and an outer surface is arranged, ii.) the inner surface of the carrier is arranged with a fixing formation, iii.) the outer surface of the carrier is arranged with a bonding formation, iv.) a driving band material is deposited on the outer surface of the carrier, v.) the driving band in the form of the carrier with deposited material is arranged for mounting on a projectile body.

[0014] According to further aspects of the improved projectile driving band manufacturing method of the invention, the following applies; t h a t deposition of material takes place by any of

[0015] - welding

[0016] - laser deposition

[0017] - electron beam deposition,

[0018] - hot isostatic pressing. t h a t the driving band material is an alloy containing copper and nickel. t h a t lubricant is provided in the driving band material before deposition. t h a t the fixing formation consists of one of

[0019] - a threaded joint

[0020] - a groove joint. t h a t the bonding formation consists of one of;

[0021] - sand blasting,

[0022] - knurling,

[0023] - threading. t h a t the hot isostatic pressing material is applied by any one or a combination of;

[0024] - winding of wire on the carrier.

[0025] - arrangement of sheet metal on the carrier,

[0026] - arrangement of straps on the carrier,

[0027] - arrangement of powder on the carrier.

[0028] In addition, the invention consists of a projectile body arranged with a driving band.

[0029] In addition, the invention consists of a projectile provided with a projectile body provided with a driving band.

[0030] BENEFITS AND EFFECTS OF THE INVENTION

[0031] In the currently existing solutions for driving bands, a metal such as copper or a copper / nickel alloy is preferably used. The driving band is preferably made of a material with properties that allow deformation of the rifling in the barrel, that is, a material that can be said to be soft, while the projectile body is preferably made of a material with high mechanical performance, such as steel. Preferably, the driving band is applied to conventional projectiles by melt deposition of the driving band on the outer surface of the projectile, which results in deterioration of the material properties of the zone between the projectile body and the driving band arranged on the projectile. Melt deposition also means that only certain materials can be used, which limits the design of the driving band. The area, the zone, between the driving band and the projectile body is where the material in the projectile body and the material in the driving band mix, resulting in poorer mechanical properties and an increased risk of cracking. The zone can be referred to as HAZ - Heat Affected Zone. As performance, such as firing distance, increases for projectiles, greater demands will be placed on the strength of the projectile, which is why various weakenings on the projectile should be minimized. By arranging the driving band in the form of a tube with a deposited coating to / on the projectile, the material performance of the projectile is not affected. Furthermore, the material of the driving band support can be freely chosen.

[0032] Furthermore, bands made of copper or copper alloys can cause material from the driving band to coat the rifling in the barrel, which can reduce the firing performance of subsequent projectiles. This is known as fire tube contamination. By manufacturing the driving band from a material that includes a smaller amount of copper or other beneficial material properties, barrel fouling can be avoided or minimized.

[0033] Furthermore, the driving band can be made lighter which reduces the weight of the projectile. Furthermore, the manufacturing method means that the design of the driving band is freer to vary and thus adapt based on the properties required. Furthermore, it is possible to achieve a driving band with lubricating properties by adding lubricant to the band material, which extends the life of the barrel. Furthermore, the improved driving band results in an increased gas pressure, which leads to a higher output speed.

[0034] LIST OF FIGURES

[0035] The invention will be described in more detail below with reference to the accompanying figures:

[0036] Fig. 1 shows a driving band in cross-section according to one embodiment of the invention. Fig. 2 shows a manufacturing method according to one embodiment of the invention.

[0037] Fig. 3 shows a machine set-up for the production of driving bands.

[0038] Fig. 4 shows a projectile body with grooves for driving bands according to an embodiment of the invention.

[0039] DETAILED DESCRIPTION OF THE EXECUTION

[0040] In Fig. 1 an embodiment of a driving band 1 is shown, comprising a carrier 2 in the form of a tube, with thickness B, where the carrier is arranged with outer deposited material 3, with thickness A, where the ring 2 and deposited material 3 are made of a load-bearing and dimensionally stable material which is dimensionally stable during the trajectory of the projectile. In order to achieve sufficient load-bearing capacity during both ejection and in the trajectory of the projectile from the ejection device to the target, the carrier is preferably made of a metal, but the carrier 2 can also be made of a ceramic or polymer and be reinforced with fibers or particles, for example carbon fiber, aramid fiber or glass fiber. The driving band 1 also has a certain width C which is adapted to the characteristics of the projectile. The surface 5 between the carrier 2 and the projectile body is designed with a fixing formation so that rotation of the driving band 1 relative to the projectile body is counteracted, for example by designing various grooves and patterns that prevent the carrier 2 from being rotated relative to the projectile body and ensure that the driving band rotates the projectile body during the ejection procedure. For example, the surface is arranged with thread formation or with slots, grooves or splines. Preferably, the deposited material 3 is formed as part of the carrier 2 preferably by depositing material on the carrier 2, but other bonding methods may also occur. Deposition is preferably done by welding, laser deposition, electron beam deposition, or by hot isostatic pressing. The surface 6 between the deposited material 3 and the carrier 2 is preferably provided with a bonding formation that facilitates the adhesion of the deposited material 3 to the carrier 2.

[0041] The projectile in the deposited position is to be retained by the deformation of the groove against the driving band. The choice of material in the deposited material 3 can thus be important for the deformation against the groove to be such that the projectile is retained. If the deposited material 3 is too hard, the deformation against the groove may be incomplete and thus the projectile will not be retained in the engaged position. Similarly, if the deposited material 3 is too soft, the deformed deposited material 3 will not be able to retain the projectile in the engaged position. In addition, the deposited material 3 seals against the barrel to prevent the gases generated by the propellant charge during ejection from leaking past the projectile. Mainly, most of the gas pressure should be created and maintained behind the projectile. Thus, the choice of material in the deposited material must be tight against the gas created by the propellant charge and be able to handle both the pressure increase and the temperature increase that occurs. Examples of materials that can be used in the deposited material are various forms of Cu / Ni alloys. Preferably, the driving band 1 is manufactured in one piece and arranged on the projectile body in a position arranged on the projectile body.

[0042] In Fig. 2, a manufacturing method of driving band 100 according to one embodiment of the invention is shown. The first step A carrier is arranged 101 comprises preparing a carrier on which material can be arranged. The carrier is preferably a tube. In the next step of the method, Fixing formation is arranged on the inner surface of the carrier, 102, the fixing formation is arranged on the inner surface of the carrier. The fixing formation may for example be in the form of a threaded joint or a grooved joint. In the case that a threaded joint is used, threaded formations are arranged on both the driving band and the projectile body so that the driving band can be threaded onto the grenade / projectile body. The grenade is designed so that the driving band is retained on the grenade when the grenade is mounted, for example so that the driving band is prevented from moving longitudinally in the grenade. In the next step, bonding formation is provided on the outer surface of the carrier 103, the outer surface of the carrier is prepared so as to improve the bonding of the deposited material to the carrier. For example, the surface may be blasted, provided with a knurling or threaded. In other embodiments, the surface may be chemically treated to improve adhesion with the deposited material. In the next step of the manufacturing method, material is deposited on the outer surface of the carrier 104, and the material is added to form the outer radius of the driving band, i.e. the part of the driving band that connects to the projectile. The material can be added in powder form, wire form or as granules, fibers or other form suitable at the time of manufacture. Further, other materials may be added to improve the performance of the completed driving band or improve the method of manufacture. In the next step, the carrier, arranged with fixing formation and with material deposited on the surface, is arranged for mounting on the projectile 105, comprising preparing a driving band adapted for mounting on the projectile. In some applications, a plurality of driving bands are prepared in a tubular form where the tube is cut into segments for preparation of a driving band. Further, the driving band may be machined to remove defects from the manufacturing process. Preferably, further machining is avoided if possible. After the manufacturing method for the driving band 100 has been carried out, a driving band has been prepared for further processing.

[0043] A driving band groove is arranged around the projectile in the projectile's rotational direction and with a certain extent in the projectile's longitudinal direction. The width and depth of the driving band groove is adapted based on, among other things, the material of the driving band, the strength of the projectile body, the caliber of the projectile and several other parameters that affect the performance of the finished projectile. The groove of the driving band is preferably arranged with some kind of pattern or structure that meets the fixing formation in the driving band that allows the driving band to be effectively coupled to the projectile body after the driving band is arranged to the projectile body. In the case that the fixing formation on the driving band is in the form of threads, threads are also arranged on the projectile body. In the case that the fixing formation is in the form of groove joints, such as splines, the corresponding groove joints are also arranged on the projectile body. The deposition of material on the carrier can be done by, for example, welding, laser deposition, electron beam deposition or hot isostatic pressing.

[0044] In the case that the deposition of material on the carrier 2 is done by welding, for example MIG welding, a wire electrode comprising a copper-nickel alloy and an inert shielding gas is preferably used. Preferably, the surface of the carrier is covered with a weld seam in one or more layers.

[0045] In the case that the deposition of material on the carrier 2 is done by laser deposition, for example Direct Laser Metal Sintering, DMLS, a laser is used to deposit the material on the carrier 2. With Direct Metal Laser Sintering, DMLS, the deposition takes place by heating one or more different powder materials and spreading them out in an even layer over the carrier 2 with, for example, 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 coating.

[0046] In the case that the deposition of material on the carrier 2 is done by electron beam, for example Electron Beam Melting, EBM, an electron beam is used to deposit the material on the carrier 2. With Electron Beam Melting, EBM, the material is deposited on the carrier 2 through layer upon layer in a vacuum chamber and utilizes an electron beam to melt metal powder that is fed from a holder / cassette, and distributed / spread on the carrier 2. The electron beam then heats the metal powder and melts the metal powder for the completion of a coated carrier. Relatively high temperature is created by the electron beam which melts the metal powder at the focal 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, furthermore, several metal powders can be utilized for the creation of a part consisting of several different materials. The part is built layer by layer.

[0047] Furthermore, the deposition of material on the carrier 2 can be done by hot isostatic pressing. Hot Isostatic Pressing (HIP) is a manufacturing process to control the grain size and structure of the material. HIP also enables the packing of metal, polymer, ceramic and composite powders into solid form. Preferably, HIP is carried out with powders but can also be carried out by arranging the deposited material as a foil, a strip, or as a sheet. The benefits 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 resistance. Furthermore, HIP can produce a dense material from metal, composite, polymer or ceramic powders without melting and 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 powder / powder components have a fine, uniform grain size and isotropic structure. Furthermore, by utilizing HIP, dissimilar metals can be joined without the need for temperature limiting binders. Through HIP, multiple diffusion bonds can be achieved in a single process cycle. HIP works for a wide range of metal alloys, as well as for example polymers and ceramic materials. Examples include alloys with nickel, cobalt, tungsten, titanium, molybdenum, aluminum, copper and iron, oxide and nitride ceramics, glass, intermetallic s and polymers. HIP allows for the joining and combining of materials that cannot otherwise be combined, i.e. composites.

[0048] After material is applied to the carrier 2 by hot isostatic pressing, various forms of heat treatment can be carried out to change the mechanical properties of the driving band. After heat treatment, if necessary, fine machining can be carried out such as cutting or grinding of the part to adapt the part based on adaptation to the projectile. By subjecting the driving band to HIP, pores / inclusions / other defects present in an additively manufactured part will be sealed or closed. Material can be applied to the carrier 2 by arranging powder in a suitable enclosing vessel or for example by additive manufacturing. The additive manufacturing, 3D printing, is preferably carried out in a vacuum in a vacuum chamber or in a pressurized chamber with an added protective gas, which means that compression in hot isostatic pressing, HIP, is possible. In the event that the additive manufacturing would take place at atmospheric pressure in air, hot isostatic pressing may result in pores not being closed in the desired manner, as the air cannot be compressed in the same way as for a part manufactured in a vacuum or in a pressurized chamber with added protective gas.

[0049] In Fig. 3 a machine set 20 is shown comprising two holding devices 22, 23 holding a carrier 2 in the form of a tube on which the deposited material 3 can be arranged with a tool 21. The tool 21 could be a nozzle for MIG welding but may also be other nozzles according to the embodiments shown. Preferably, the carrier 2 can be rotated and the tool 21 moved longitudinally of the carrier to coat the carrier 2 with the deposited material 3. Once the carrier 2 is coated with the deposited material 3, the completed driving band component can be cut to the correct dimension, for example by sawing or turning or other methods to cut the driving band component to the correct size.

[0050] In Fig. 4, a projectile body 10 is shown comprising a groove 11 in which a driving band 1 can be arranged. The projectile body 10 preferably comprises a front portion 10' and a rear portion 10", which can be forged or machined from a blank to form a common body for a projectile. The front portion 10' of the projectile body is arranged to the rear portion 10" by, for example, threaded joining, adhesive joining, welding, soldering, shrink fitting or other methods of joining the two portions to each other. Preferably, the projectile body is hollow for the arrangement of a load in the projectile body, which may comprise, for example, warheads, but may also comprise explosives or other loads suitable for a projectile. The projectile body is also preferably arranged such that a fuze can be arranged on the projectile body, preferably such that a fuze can be arranged by means of a threaded connection in the front part of the projectile body. The groove 11 may be machined in the front part 10' of the projectile body or on the rear part 10" of the projectile body or otherwise arranged at the time of manufacture of the projectile body, and adapted in both depth, in the radial extent of the projectile body, and length, in the longitudinal extent of the projectile body. The size of the groove 11 is adapted based on the size of the driving band 1 to ensure, among other things, that the driving band 1 achieves the required strength so that the driving band remains attached to the projectile body during manufacture, attachment and ejection without too much material being removed from the projectile body 10 during the arrangement of the groove 11 so as not to adversely affect the strength of the projectile body 10. The surface 12 of the groove 11 may be arranged with patterns or other embodiments to allow the driving band 1 to achieve good adhesion to the projectile body 10 when the driving band 1 is arranged on the projectile body 10. For example, the surface may be provided with threads or grooves, which allow the driving band 1 disposed on the projectile body 10 to achieve good adhesion to the projectile body 10 such that torque at the time of projectile ejection, from the barrel groove, is transmitted to the driving band 1 and then the projectile body 10 without the driving band 1 becoming loose or otherwise failing to adequately adhere to the projectile body 10. Other patterns or coatings may also be provided on the surface 12 to ensure that the driving band 1 adheres to the projectile body 10. Preferably, the driving band 1 is arranged on the projectile body 10 without heating the driving band, for example by threading the driving band 1 onto the projectile body 10 or by sliding the driving band 1 on the projectile body so that grooves or splines arranged on the projectile body 10 meet sockets arranged on the driving band 1.

[0051] FUNCTION DESCRIPTION

[0052] The function and use of a projectile arranged with driving band 1 according to the invention is as follows. In the case of artillery ammunition, the projectile and the propelling charge are usually separate units and thus the launching device, often referred to as a gun or cannon, is first loaded with the projectile which is placed, also referred to as set, in the barrel, after which the propelling charge is placed behind the projectile. When the projectile is placed in the barrel, the projectile is moved forward so that the driving band 1 is partially deformed and coupled to the rifling in the barrel. The projectile is retained in the barrel by deformation of the driving band 1 against the barrel groove. Behind the projectile, propellant adapted to the firing condition is placed. The chamber is then sealed with preferably a screw or wedge. For ignition, a primer or other ignition device is used to ignite the propellant. When the propellant burns, gas is generated which, depending on the gas pressure, forces the projectile through the barrel. The gas pressure generated by the ignition of the propellant behind the projectile depends on the chemical and physical properties of the propellant, the weight of the projectile and the friction between the driving band of the projectile and the barrel. In order to rotationally stabilize projectiles, the rifling has a pitch in the barrel to rotate the driving band 1 and thus the projectile in the barrel and thus rotate and rotationally stabilize the projectile in the trajectory after the projectile has left the barrel. Alternatively, the projectile may be in the form of a cartridge ammunition round, in which case the projectile is mounted in a case enclosing a propellant, preferably in the form of gunpowder. The ammunition round preferably also includes an ignition device for initiating the propellant, often in the form of electrical ignition or mechanical ignition by impact. Cartridge ammunition is preferably used in the medium caliber range while larger projectiles, such as for artillery, preferably the projectile is separated from the propellant charge.

[0053] EXAMPLE OF EXECUTION

[0054] Examples of projectiles with driving bands are a 40 mm, 57 mm, 76 mm, 105 mm or 155 mm shell where stabilization in the shell's trajectory is achieved by rotational stabilization.

[0055] Furthermore, the projectile may also be equipped with an obturator to prevent gas leakage to the driving band during the ejection process which may affect the driving band through material consumption. The obturator is thus placed closer to the rear of the projectile relative to the driving band, if applicable.

[0056] ALTERNATIVE EMBODIMENTS

[0057] The invention is not limited to the particular embodiments shown, but can be varied in different ways within the scope of the claims

[0058] For example, it is recognized that the number, size, material and shape of the elements and details included in the driving band are adapted to the weapon system(s) and other design characteristics of the moment.

[0059] It is recognized that the manufacturing methods and projectile designs described above with a driving band may include several different dimensions and projectile types depending on the area of use and the barrel width. However, the above refers to at least the currently most common types of shells between about 20 mm - 200 mm.

Claims

PATENT CLAIMS1. Method of manufacturing a driving band (100) for a projectile, characterized in that the driving band (1) is manufactured from a coated carrier (2) according to the following method steps i.) a carrier (2) in the form of a tube with an inner surface and an outer surface is provided, ii.) the inner surface of the carrier (2) is arranged with fixing formation, iii.) the outer surface of the carrier is arranged with a bonding formation, iv.) a driving band material is deposited on the outer surface of the carrier (2), v.) driving band (1) in the form of the carrier (2) with deposited material (3) is arranged for mounting on a projectile body.

2. A method of manufacturing a driving band (100) for a projectile according to claim 1, characterized in that the deposition of material is by any of- welding,- laser deposition,- electron beam deposition,- hot isostatic pressing.

3. A method of manufacturing a driving band (100) for a projectile according to any of the preceding claims, characterized in that the driving band material is an alloy comprising copper and nickel.

4. A method of manufacturing a driving band (100) for a projectile according to any of the preceding claims, characterized in that lubricant is provided in the driving band material before deposition.

5. A method of manufacturing a driving band (100) for a projectile according to any one of the preceding claims, characterized in that the fixing formation consists of any one of- a threaded joint,- a spline joint.

6. A method of manufacturing a driving band (100) for a projectile according to any one of the preceding claims, characterized in that the bonding formation consists of any one of;- sand blasting,- knurling,- threading.

7. A method of manufacturing a driving band (100) for a projectile according to claim 2, characterized in that the material for the isostatic pressing is applied by any one or a combination of- winding of wire on carrier (2),- arrangement of sheet metal on the carrier (2),- arrangement of strip on the carrier (2),- arrangement of powder on the carrier (2).

8. A projectile body (10) provided with a driving band (1), characterized in the driving band is manufactured by the driving band manufacturing method according to any of claims 1 - 7.

9. A projectile arranged with a projectile body (10) arranged with a driving band (1), characterized in the projectile is arranged with a projectile body according to claim 8.

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