RU2760119C1 - Method for manufacturing a bullet - Google Patents

Abstract

FIELD: weapons.

SUBSTANCE: invention relates to production of weapons and can be used in manufacture of projectiles, in particular, tungsten alloy bullets. Two annular grooves are cut from a tungsten alloy on a workpiece, a galvanic nickel coating is applied to the surface of the grooves. Two rings are pre-made from a copper rod so that each ring would fit tightly into an annular groove made on the tungsten alloy workpiece and the outer diameter of each ring is greater than the diameter of the workpiece. A galvanic nickel coating is applied to the inner surface of the halves of the rings. The copper rings are installed in the grooves, pressed against the workpiece, and the rings are soldered. The outer surface of the soldered rings is then turned so that the diameter thereof is greater than the diameter of the tungsten alloy workpiece, followed by finishing turning of the workpiece for manufacture of a bullet.

EFFECT: invention provides a possibility of increasing the accuracy of firing, the range of projectiles and the operating life of the weapon barrel in repeated shooting by ensuring the integrity of the inner surface of the bore.

1 cl, 2 ex

Description

The invention relates to the production and manufacture of small arms ammunition, in particular, tungsten alloy bullets.

Tungsten alloy bullets are harder than rifled maraging steel. For this reason, when a bullet rotates and escapes from such a barrel, nadirs appear on the inner surface of the barrel bore, leading to deformation of the surface of the channel. As a result of the further use of weapons with a deformed surface of the barrel bore, the accuracy during firing and the flight range, as well as the service life of the barrel, decrease.

From patent RU 2287769 C1, 20.11.2006 (F42B 12/04), a method for manufacturing an axisymmetric bullet shell is known, including making a steel billet with a thickening in the head and thin-walled part in contact with the surface of the barrel bore. The thickened part of the shell or its separate axisymmetric section is imparted with increased strength and hardness in comparison with the strength and hardness of the thin-walled part of the shell. The surface of the shell is covered with a protective layer. This method allows you to increase the penetration capacity of the bullet, as well as the accuracy of fire and the resource of the barrel. However, this method does not provide the same results for bullets made from tungsten alloys.

The manufacture of bullets from tungsten is known, for example, from patent RU 2528483 C1, 09/20/2014 (F42B 5/02).

Closest to the proposed method of making a bullet is considered in patent RU 2112205 C1, 05/27/1998 (F42B 30/02) (Prototype). The invention relates to ammunition for small arms and can be used in the design of a universal bullet for weapons intended for shooting in air, under water, from air to water and from water to air. The bullet is made in the form of an elongated rod with a truncated cone in the front part to ensure the formation of a cavitation cavity when moving in an aqueous medium. The bullet has two parts. The front part of the bullet has a high average density, and the rear part has a lower density. The front is made of a heavy alloy, such as tungsten, and the back is made of a light alloy. The rear part has a relief, for example, in the form of caliber plumage. This method of making a bullet made it possible to solve the problem of stabilizing the flight of a bullet in different environments.

The disadvantage of the prototype is that during the rotation and departure of the bullet from the gun barrel, its deformation occurs, due to the contact of a bullet made of tungsten alloy, which has a higher hardness compared to the barrel material, nadirs appear on the inner surface of the barrel bore, which increases its wear, decreases survivability of weapons, there is a possibility of a breakthrough of powder gases. In addition, when bullets exit the bore, they acquire unacceptable nutation angles, the movement of bullets along the trajectory becomes less stable and, as a result, the external ballistic characteristics of the weapon (initial bullet velocity, firing range) deteriorate.

The tasks that the proposed invention solves are to increase the accuracy during firing and the range of bullets made of tungsten alloy, and increase the service life of the gun barrel during repeated firing by ensuring the integrity of the inner surface of the barrel bore.

To solve the set tasks, a method is proposed for manufacturing a bullet from a tungsten alloy, including cutting two annular grooves on a workpiece from a tungsten alloy. Copper rings are tightly installed in the grooves, having previously applied a galvanic nickel coating to the surface of the grooves and the inner surface of the rings. Then the rings are soldered at a temperature of 265-285 ° C. The outer surface of the soldered rings is further sharpened so that their diameter is greater than the diameter of the workpiece. After that, the final turning of the workpiece is performed to make the bullet.

The following is a detailed disclosure of the proposed invention.

In the manufacture of bullets, tungsten alloys with high density and hardness are used to make them heavier, for example, such alloys as VNZh 7-3, VD-25, VD-30, VNM 5-3. Two annular grooves 0.8-1.0 mm deep and 3 mm wide are cut on a tungsten alloy rod 50-60 mm long, intended for making a bullet. The distance between the grooves is 8-10 mm. The grooves should not have sharp corners that are stress concentrators. The surface of the grooves is subjected to degreasing, pickling and nickel plating. The remaining surfaces of the bar are insulated with varnish before nickel plating. To insulate the surfaces of the bar that are not subject to coating, you can use PVC varnish KhVL-21, epoxy varnish.

Degreasing is carried out in a solution of the following composition, g / l: caustic soda 5-10, sodium carbonate 20-40, trisodium phosphate 20-40. The processing temperature is 60-80 ° C, the current density at the cathode is 2-10 A / dm ² , the processing time is 3-10 minutes. It is also possible to carry out electrochemical degreasing in the specified solution by sequential polarity switching (cathode-anode). This eliminates the diffusion of hydrogen into the metal of the bar.

Etching of defatted workpieces for removing the oxide film from the metal is carried out in a solution of the following composition, wt. %: caustic potassium 5, potassium hexacyanoferrate 25, water 70, room temperature. The bar can also be etched in a 5-15% sodium hydroxide solution. The bar is then rinsed with water-blasted surfaces.

On the surface of the grooves, a nickel plating is then applied. The thickness of the nickel coating is 3-5 microns. To improve the adhesion of the coating to the surface of the grooves, it is desirable to carry out activation or passivation before coating. The essence of activation is the removal of the thinnest oxide films by chemical or electrochemical methods in solutions consisting of a mixture of acids. Passivation consists in the formation of a thin passive porous film on the surface of the parts, which is subsequently restored during electrolysis during the coating process and then ensures high activity of the substrate surface and strong adhesion of the coating to it.

Pre-nickel plating electrolyte composition: nickel chloride 250 g / l, hydrochloric acid 180-220 ml / l. The processing temperature is 40-50 ° C, the current density at the cathode is 5-6 A / dm. Then, a nickel coating is immediately applied to the required thickness from an electrolyte of the following composition, g / l: nickel sulfate 140-200, nickel chloride 30-40, sodium chloride 10, boric acid 25-30, sodium sulfate 60-80, pH = 5, 2-5.8. Treatment temperature 20-55 ° C, current density 0.5-0.8 A / dm. After applying the nickel coating, the workpieces are washed, dried, and the varnish is removed from the protected surfaces.

This sequence of operations ensures good adhesion during the subsequent brazing of the tungsten alloy bar with copper rings.

Rings are pre-made from a copper rod. The dimensions of the rings should be such that each ring fits snugly into the groove made on the tungsten alloy blank. In this case, the outer diameter of the ring must be greater than the diameter of the workpiece. The outer diameter of the ring is made with an allowance for its final turning. Each ring can be cut into two halves for easy insertion into the grooves of the workpiece. At the stage preceding the assembly of the workpiece with grooves and rings, a 3-5 µm thick electroplated nickel coating is also applied to the inner surface of the ring halves.

Before making the ring, the bar is annealed at a temperature of 600 ° C for 20-25 minutes. in a vacuum or inert atmosphere. This will allow obtaining a homogeneous structure of copper, increasing its ductility and relieving stress. Heating and cooling of the ring is carried out in a gentle mode in order to avoid the leash due to deformation.

Next, a 0.1 mm thick foil of PSrOSu8 solder (VPr-6, silver 8.5%) is installed in the grooves. You can also use solder PSrMO5 (VPr-9, silver 5.5%) 0.1 mm thick. These solders are made on the basis of tin and contain silver and antimony, and VPr-9 additionally copper, have high corrosion resistance and are used in all climatic conditions without protection by coatings.

On top of the solder, rings or half rings are installed and pressed against the bar. Laser welding is used to weld at the joints of the halves of the rings, ensuring tight contact of the surfaces of the welded ring with the surface of the solder on the bar. The need for tight contact between the ring and the bar is due to the provision of high-quality soldering between them.

Then the rings are soldered at a temperature of 275-285 ° C when using PSrOSu8 solder or at 265-275 ° C in the case of using PSrMO5 solder. The composition of the flux is as follows, wt. %: rosin 22, aniline hydrochloric acid 2, ethyl alcohol 76.

Soldering the rings under the indicated modes contributes to good adhesion of copper rings to the surface of the tungsten alloy, which is necessary for further machining of the bar with soldered rings in the process of the final manufacture of the bullet.

The outer surface of the brazed copper rings is further sharpened so that the final diameter of the rings is 4 ± 2 μm (0.002-0.006 mm) larger than the diameter of the tungsten alloy workpiece. The workpiece itself is then turned to make the final bullet. As a result, a bullet is obtained from a tungsten alloy with annular inserts of soldered copper rings protruding from the surface of the bullet by 2 ± 1 μm (0.001-0.003 mm).

When fired by such a bullet, its contact with the surface of the barrel bore will occur along the protruding surface of the copper ring, and not along the surface of the tungsten alloy. Since copper is a softer metal than tungsten and the steel from which the barrel is made, nadir and any other damage will not occur on the inner surface of the barrel.

The invention is supported by the following examples.

Example 1.

Two annular grooves 1 mm deep and 3 mm wide were cut on a rod made of VD-25 tungsten alloy 50 mm long, the distance between the grooves was 8 mm. The surface of the grooves was degreased, etched, and a 3–5 µm thick electroplated nickel coating was applied. The surfaces of the bar that were not to be coated were pre-insulated with epoxy varnish. Two rings were made from a copper bar in such a way that each ring fits snugly into an annular groove made on the bar. Each ring was cut into two halves, and a 3-5 µm thick electroplated nickel coating was applied to the inner surface of the ring halves. A PSrOSu8 solder foil with a thickness of 0.1 mm was installed in the grooves. On top of the solder, two halves of copper rings were installed in each groove and pressed tightly against the tungsten alloy rod. Carried out laser welding of the halves of the rings at the joints. At the same time, tight contact of the surfaces of the welded ring with the surface of the solder on the bar was ensured. Then the rings were soldered at a temperature of 275-285 ° C (280 ± 5 ° C). The outer surface of the soldered rings was further sharpened so that their diameter was 4 ± 2 μm larger than the diameter of the tungsten alloy rod. After that, the bullet was finally made by turning

Example 2.

On a rod made of tungsten alloy VNM 5-3 60 mm long, two circular grooves with a depth of 0.8 mm and a width of 3 mm were cut, the distance between the grooves was 10 mm. The surface of the grooves was degreased, etched, and a 3–5 µm thick electroplated nickel coating was applied. The surfaces of the bar that were not to be coated were pre-insulated with epoxy varnish. Two rings were made from a copper bar in such a way that each ring fits snugly into an annular groove made on the bar. Each ring was cut into two halves, and a 3-5 µm thick electroplated nickel coating was applied to the inner surface of the ring halves. A 0.1 mm thick PSrMO5 solder foil was installed in the grooves. On top of the solder, two halves of copper rings were installed in each groove and pressed tightly against the tungsten alloy rod. Carried out laser welding of the halves of the rings at the joints. At the same time, tight contact of the surfaces of the welded ring with the surface of the solder on the bar was ensured. The soldering of the rings was carried out at a temperature of 265-275 ° С (270 ± 5 ° С). The outer surface of the soldered rings was further sharpened so that their diameter was 4 ± 2 μm larger than the diameter of the tungsten alloy rod. After that, the bullet was finally made by turning.

As a result of comparative tests using bullets made in accordance with the proposed invention and conventional bullets made of tungsten alloy, it was found that in the case of using the proposed bullets on the inner surface of the barrel bore after repeated shots, no damage occurs, in contrast to the use of conventional bullets. which leads to an increase in the accuracy and range of flight when firing, as well as to an increase in the service life of the barrel with repeated firing.

Claims (1)

A method of making a bullet from a tungsten alloy, characterized in that two annular grooves are cut on a tungsten alloy workpiece, into which copper rings are tightly installed, having previously applied a galvanic nickel coating to the surface of the grooves and the inner surface of the rings, then the rings are soldered at a temperature of 265-285 ° C, the outer surface of the soldered rings is further sharpened so that their diameter is greater than the diameter of the workpiece, after which the final turning of the workpiece is performed to make a bullet.