Projectile with belt and belt manufacturing method

Abstract

The invention relates to a manufacturing method for an obturating ring (100) for a projectile where the obturating ring (1) is cast onto a projectile body (10) in a mold arranged on the projectile body comprising the following method steps; i.) a mold is arranged on the projectile body (10), ii.) the mold is heated, iii.) material is added to the mold, iv.) the mold cools, v.) the mold is removed. The invention further consists of a projectile body arranged with an obturating ring and a projectile.

Description

PROJECTILE WITH BELT AND BELT MANUFACTURING METHODTECHNICAL FIELD

[0001] The present invention relates to a manufacturing method for a belt for a projectile where the belt is cast onto a projectile body in a mold arranged on the projectile body comprising the following method steps; i.) a mold is arranged on the projectile body, ii.) the mold is heated, iii.) material is added to the mold, iv.) the mold cools, v.) the mold is removed. The invention further consists of a projectile body arranged with a belt and a projectile.BACKGROUND OF THE INVENTION, PROBLEM AREA AND STATE OF THE ART

[0002] Obturating rings, also known as belts, are used on projectiles fired from barrels to provide both a gas seal between the projectile and the barrel as well as an effective frictional connection against the barrel. Traditionally, projectiles are rotationally stabilized in order to achieve better aerodynamic properties by causing the projectile to rotate during the firing process as a result of rifling in the barrel. When the projectile outfitted with a belt is propelled out of the barrel, the belt is partially deformed by the rifling and thus the belt grips the rifling and rotates the projectile in a manner corresponding to the pitch of the rifling. If a steerable projectile is desired, it is advisable that the projectile does not rotate when fins are extended and are used to instead fin-stabilize the projectile. As it is desirable to use the same barrel, and thus the same launch device, for all projectiles, the construction of the steerable projectiles includes a sliding belt which allows them to be fired from a grooved barrel. The sliding belt of the steerable projectile engages the rifling in the barrel and creates a gas seal. As the projectile is propelled into the barrel, the belt rotates with the pitch of the rifling. The connection between the belt and the projectile is such that the friction is low and a slip or slide against the projectile occurs, which means that the projectile either does not rotate or rotates with a significantly smaller rotationthan in cases where a fixed mounted belt is used. As the projectile exits the barrel, the projectile rotation will be low.

[0003] For projectiles that are to be rotationally stabilized, it is important that the belt is fixed to the projectile so that the belt does not rotate relative to the projectile and that the rifling in the barrel deforms the belt without the belt rotating relative to the rifling in the barrel.

[0004] Patent document US 4,532,868 demonstrates a rotating belt comprising a rotatable outer ring of metal alloy comprising bronze / tin, which is press-fitted onto an inner ring of for example bronze or aluminium.

[0005] Rotatable, or slipable, belts are common on fin-stabilized ammunition and are often made of a softer metal, for example copper, or of a polymer or composite material. These belts are slippery against the projectile body and low friction between the belt and the projectile is necessary to get as little rotation of the projectile as possible. Rotatable belts cannot therefore be used for rotationally stabilized projectiles where the belt must instead connect to the projectile and rotate the projectile during the launch process.

[0006] For projectiles that are to be rotationally stabilized, a belt made out of a soft metal with melt deposition is often arranged, which negatively affects the material properties of the projectile. The use of belts made of soft metal can also lead to barrel contamination as material from previously extended belts gets stuck in the barrel with negative consequences for the performance of the barrel.PURPOSE AND FEATURES OF THE INVENTION

[0007] By the use of compression molding of a polymer against / on / to the projectile body, problems related to material weakening in the projectile body can be minimized or completely avoided. Furthermore, the use of a polymer can avoid previously known problems with barrel contamination when metalresidues from the belt from previously fired projectiles stick to the barrel. Furthermore, a manufacturing method including compression molding is cheaper than previously known methods.

[0008] The invention consists of a manufacturing method for an obturating ring for a projectile, where the obturating ring is cast onto a projectile body, where the projectile body is arranged with a groove for the obturating ring surrounding the projectile in the projectile's rotational direction and with an extension in the longitudinal direction of the projectile, and where the groove for the obturating ring is arranged with a pattern or structure that enables that the belt is effectively connected to the projectile body after the belt is arranged to the projectile body, in a mold arranged on the projectile body including the following method steps; i.) a mold is arranged on the projectile over the groove for the obturating ring ii.) the mold is heated, iii.) material is added to the mold, iv.) the mold cools down, v.) the mold is removed.

[0009] According to additional aspects of the improved projectile obturating ring manufacturing method of the invention include; that material is supplied to the mold under pressure. that the material consists of a polymer. that the polymer is PEEK. that the polymer is fiber reinforced.

[0010] That an elevation on the belt is angled for wedge-shaped application against the rifling of the barrel. that the length of the chamfer made for the increase constitutes 10% - 80% of the total width of the belt.

[0011] In addition, the invention consists of a projectile body arranged with an obturating ring

[0012] In addition, the invention constitutes a projectile arranged by a projectile body arranged with an obturating ring.THE ADVANTAGES AND EFFECTS OF THE INVENTION

[0013] In the currently existing solutions for belts, a metal such as copper or a copper / nickel alloy is preferably used. The belt part is preferably made of a material with properties that enable deformation of the fluting in the barrel 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 belt is applied to conventional projectiles by means of melt deposition of the belt on the outer surface of the projectile, which results in deteriorated material properties in the zone between the body of the projectile and the belt arranged on the projectile. The area, the zone, between the belt and the projectile body is mixed between the material in the projectile body and the material in the belt, which results in poorer mechanical properties and an increased risk of cracks. The zone can be termed HAZ - Heat Affected Zone. Since performance, such as firing distance, increases for projectiles, greater demands will be made regarding the strength of the projectile, which is why various weakened areas of the projectile should be minimized. By arranging the belt by means of press molding a polymer on the projectile, the material performance in the projectile is not affected.

[0014] Furthermore, belts made out of copper or copper alloys can cause material from the belt to coat the fluting in the barrel, which can result in reduced firing performance for subsequent projectiles. This is called barrel infection. By manufacturing the belt from a material that does not contain copper, barrel contamination can be avoided or minimizedLIST OF FIGURES

[0015] The invention will be described below by reference to the figures that are included there:

[0016] Fig. 1 shows a cross-section view of a wedge according to one embodiment of the invention.

[0017] Fig. 2 shows a manufacturing method according to an embodiment of the invention.

[0018] Fig. 3 shows a projectile body with a groove for a belt according to one embodiment of the invention.DETAILED DESCRIPTION OF EMBODIMENT

[0019] During typical molding, two press plates are used, between which there is a molding tool. The material is placed in the cavity of the mold, when pressed together the material fills the cavity. To be sure that the products will get the right shape, the forming press must be loaded with more material than the product requires.

[0020] Disadvantages of compression molding are that material must be arranged in the cavity of the molding tool, which takes time, and that extra material, to ensure that the entire mold is filled, must be added, which can result in a lot of beards being created, which causes wastage during manufacturing and also take time to remove.

[0021] Fig. 1 shows an embodiment of a belt 1 in a design consisting of a ring 2, with thickness B, where the belt can be made with an elevation 3, with thickness A, where the ring 2, and the elevation 3, is made of a load-bearing and dimensionally stable material which during the trajectory of the projectile is dimensionally stable.

[0022] In order to achieve sufficiently good load-bearing capacity both during launch and in the trajectory of the projectile from the launch device to the target, the inner ring 2 can be reinforced with fibers or particles, for example carbon fiber, aramid fiber or glass fiber. In order to achieve sufficiently good load-bearing capacity both during launch and in the trajectory of the projectile from the launch device to the target, the inner ring 2 can be reinforced with fibers or particles, for example carbon fiber, aramid fiber or glass fiber. The surface 5 between the inner ring 2 and the projectile body is designed so that rotation of the belt 1 relative to the projectile body is counteracted, for example by designing various grooves and patterns that prevent the ring 2 from being rotated relative to the projectile body and ensures that the belt rotates the projectile body during the launch procedure. The elevation 3 is preferably made as part of the ring 2, but can also be a separate ring which is arranged to the inner ring 2 by chemical, thermal or mechanical bonding, but other bonding methods can also occur. Examples of chemical bonding are vulcanization or gluing. An example of thermal bonding is to dimension the outer diameter of ring 2 slightly larger than the inner diameter of the elevation 3 and mount the elevation 3 in a heated, and thus in an expanded state. An example of mechanical connection is to provide the inner ring 2 with pins or nets against which the outer, possibly softer, elevation 3 is mounted and thus connected to the inner ring 2.

[0023] The elevation 3 is preferably elastic and is designed to effectively grip the fluting in the fire tube when the projectile is attached. For example, an angle, not shown in the figure, or a chamfer on the front edge of the belt may occur. The projectile must be retained in the applied position by the deformation of the belt by the ribbing. The belt part 1 can be made with a chamfer with the depth A which constitutes the height of the elevation 3.c The choice of material in the elevation 3 can thus be important for the deformation against the ribbing to be such that the projectile is retained. If the elevation 3 is too hard, the deformation against the ribbing may be incomplete and thus the projectile is not retained in the engaged position. Similarly, if the elevation3 is too soft, the deformed elevation 3 will not be able to retain the projectile in the engaged position. Additionally, the elevation 3 creates a seal against the barrel, ensuring that gases produced by the propellant charge during firing do not leak around the projectile. Mainly, most of the gas pressure must be created and maintained behind the projectile. Thus, the chosen material for the elevation 3 creates a seal 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 elevation 3 a polymer, such as an elastomer Preferably, the ring 2, possibly with an increase 3, is manufactured in one and the same material at the same time of manufacture in order to reduce the costs in the production of the belt.

[0024] Fig. 2 shows target areas for a target according to one embodiment of the invention. The first step A projectile body with a groove for a belt is completed 101 includes that a projectile body is completed including a groove for the belt. The track for the belt is arranged enclosing the projectile in the projectile's rotational direction and with a certain extension in the projectile's longitudinal direction. The width and depth of the groove for the belt is adapted based on, among other things, the material in the belt, the strength of the projectile body, the caliber of the projectile with several different parameters that affect the performance of the completed projectile. The track for the belt is preferably arranged with some form of pattern or structure that enables the belt to be effectively connected to the projectile body after the belt has been arranged to the projectile body. In the next step of the method, A rnold is placed on the projectile over the groove for a belt 102, then a mold is placed on the projectile so that the belt is enclosed. The mold is so arranged that a cavity is created over the groove for the belt so that a belt can be cast directly in place on the projectile by means of the mold. A certain seal exists between the mold and the projectile so that material can be fed into the mold to create a belt. In the next step, Heating of mold and projectile 103, the mold is heated and also, where applicable, the projectile body, heating can take place with a heat-generating device arranged in the mold,such as a heating element, or with an external heating device that supplies heat to the mold and possibly also the projectile body. In the next step in the manufacturing method, Material is added under pressure 104, the material that will make up the belt is added to the mold. Material can be supplied in liquid form, that is to say that the polymer is heated to melting point before supply to the mold, or by the material being supplied in solid form, for example as pellets, to the mold and melted in the mold. The material is preferably supplied under pressure so that it is possible to ensure that the material is distributed in the mold and that the mold is completely filled. In the next step, Setting 105, the mold and projectile body are allowed to cool to ensure that the added material returns in solid form. Cooling can be performed by waiting for the mold and projectile to cool to ambient temperature, but can also be done by actively cooling down the mold and projectile body by adding cooling. In the next step, which takes place after the belt has cooled to become completely or partially in solid form, the mold is removed 106, so the mold can be detached from the projectile body arranged with the belt. In the final step, Optional Finishing of Belt 107, the belt may be machined to remove casting defects. Preferably, further processing is avoided if possible. In the event that processing is carried out, processing takes place, for example, through cutting processing such as turning. After the manufacturing method for belt 100 has been carried out, a projectile body has been arranged with

[0025] Fig. 3 shows a projectile body 10 comprising a groove 11 where a belt can be arranged. The projectile body 10 may be forged or machined from a blank to create a body for a projectile. The projectile body 10 can be forged or machined from a blank to create a body for a projectile. The projectile body is preferably hollow for the arrangement of a load in the projectile body which can consist of, for example, combat parts but can also consist of explosives or other loads suitable for a projectile. The projectile body is also preferably arranged so that a fuze can be arranged on the projectile body, preferably so that a fuze can be arranged by means of a threaded connection in the front part of the projectile body. The groove 11 can be machined into the projectile body or arranged inother ways when the projectile body is manufactured, and adapted in both depth, in the radial extension of the projectile body, and length, in the longitudinal extension of the projectile body. The size of the groove 11 is adapted based on the size of the belt 1 in order to ensure, among other things, that the belt 1 achieves the requirements regarding strength so that the belt remains on the projectile body during manufacture, attachment and launch without too much material being removed from the projectile body 10 when arranging the groove 11 in order not to adversely affect the strength of the projectile body 10. The surface 12 of the groove 11 can be arranged with patterns or other embodiments to enable the belt 1 to achieve good adhesion to the projectile body 10 when the belt 1 is arranged on the projectile body 10. For example, the surface 12 can be lightly scratched, for example to create cross-lettering, which means that the belt 1 cast on the projectile body 10 gets good adhesion to the projectile body 10 so that torque when the projectile is ejected, from the knurling in the barrel, is transferred to the belt 1 and then the projectile body 10 without the belt 1 detaches or otherwise does not adhere to the projectile body 10 in an effective way. Other patterns or surface coatings can also be arranged on the surface 12 to ensure that the belt 1 adheres to the projectile body 10.DESCRIPTION OF FUNCTIONS

[0026] The function and use of a projectile arranged with belt 1 according to the invention is as follows. In the case of artillery ammunition, the projectile and the propellant charge are usually separate units and thus the launching device, often called a piece or cannon, is loaded first with the projectile which is placed, also called set, in the firing tube, after which the propellant charge is placed behind the projectile. When the projectile is attached, the projectile is moved forward into the firing tube so that the belt 1 is partially deformed and connected to the groove in the firing tube. The projectile is retained in the firing tube by deformation of the belt 1 against the fluting in the firing tube.

[0027] Behind the projectile is placed a propellant adapted to the firing ratio. Then the chamber is preferably closed with a screw or wedge. When igniting, an ignition cartridge or other ignition device is used which over-ignites the propellant. When the propellant burns, gas is generated which, depending on the gas pressure, pushes the projectile through the barrel. The gas pressure that occurs upon ignition of the propellant behind the projectile depends partly on the chemical and physical design of the propellant, but also on the weight of the projectile and the friction that forms between the belt (100) of the projectile 100 and the rifling of the barrel. To rotationally stabilize projectiles, the rifling has a pitch in the barrel to rotate the belt 1 and thus the projectile in the barrel and thus rotate and rotationally stabilize the projectile in the trajectory after the projectile leaves the barrel.

[0028] An alternative design of the projectile can be in the form of a cartridge ammunition shot when the projectile is mounted in a sleeve that encloses a propellant, preferably in the form of gunpowder. The ammunition round preferably also includes an ignition device for propellant initiation, often in the form of electrical ignition or mechanical ignition by impact. Cartridge ammunition is preferably used in the medium caliber range, while for coarser projectiles, such as for artillery, the projectile is preferably separated from the propellant charge.EXAMPLES OF EMBODIMENTS

[0029] An example of a projectile with a belt is a 40 mm, 57 mm, 76 mm, 105 mm or 155 mm artillery shell where stabilization in the shell's trajectory takes place through rotational stabilization.ALTERNATIVE EMBODIMENTS

[0030] The invention is not limited to the embodiments specifically shown, but can be varied in different ways within the framework of the claims.

[0031] It is understood, for example, that the number, size, material and shape of the elements and details included in the remaining sliding belt are adapted to the weapon system(s) and other design features that are currently available.

[0032] It is understood that the above-described projectile designs with a remaining sliding belt can include several different dimensions and projectile types depending on the area of use and barrel width. However, the above refers to at least the most common types of grenades today of between about 20 mm - 200 mm.

Claims

Claims1. Manufacturing method for obturating ring (100) for a projectile, characterized in that the obturating ring (100) is cast on a projectile body (10), where the projectile body (10) is arranged with a groove for the obturating ring surrounding the projectile in the rotational direction of the projectile and with an extension in the longitudinal direction of the projectile, and where the groove for the obturating ring is arranged with a pattern or structure that enables that the obturating ring is effectively connected to the projectile body after the obturating ring is arranged to the projectile body, in a mold arranged on the projectile body including the following method steps; i.) a mold is arranged on the projectile (10) over the groove for the obturating ring, ii.) the mold is heated, iii.) material is added to the mold, iv.) the mold cools down, v.) the mold is removed.

2. Manufacturing method for obturating ring (100) for a projectile according to claim 1 , characterized in that material is supplied to the mold under pressure.

3. Manufacturing method for obturating ring (100) for a projectile according to one of the above claims, characterized in that the material consists of a polymer.

4. Manufacturing method for obturating ring (100) for a projectile according to claim 3, characterized in that material is PEEK.

5. Manufacturing method for obturating ring (100) for a projectile according to claim 3, characterized in that the polymer is fiber-reinforced.

6. Manufacturing method for obturating ring (100) for a projectile according to one of the above claims, characterized in that an elevation (3) on the obturating ring (1 ) is angled for wedge-shaped engagement against the fluting of the fire tube.

7. Manufacturing method for obturating ring (100) for a projectile according to claim 6, characterized in that the length (C) of the chamfer made for the elevation (3) constitutes 10% - 80% of the total width (C) of the belt (1 ).

8. Projectile body (10) arranged with obturating ring (1 ), characterized in that the obturating ring is manufactured using an obturating ring manufacturing method according to any of claims 1 - 7.

9. Projectile arranged by projectile body (10) arranged with obturating ring (1 ), characterized in that the projectile is arranged with a projectile body according to claim 8.

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