RU2406589C1 - Method of producing splitter shell with band - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of ammunition. Hollow cup- or tube-like billet is successively reduced. Grids of spiral grooves are made on the billet inner surface. Billet is pre-arranged on the mandrel with spiral ledges made in opposite directions. Hollow billet made from structural steel is used, steel carbon content making up to 0.4 %. Billet reduction is performed using liquid or solid lubricant. Billet OD exceeds bend diametre by allowance. Reduction is performed with strain that provides for hardness not over 250 HV. Groove depth makes 0.215-0.249 of the hollow billet wall thickness. Billet is removed from the mandrel. Now, the billet is machined to produce the band.

EFFECT: longer life of tool, better fragmentation of shell.

6 cl, 5 dwg

Description

The invention relates to a method for the manufacture of ammunition, and more particularly fragmentation shells stabilized by rotation and having a shell with notches in the form of spiral grooves inside pipes pressed through dies.

In the patent RU No. 2248514, IPC F42B 12/22, a method for manufacturing an artillery shell body is described. According to this method, the shell of the projectile is made of two parts: a cylindrical shell of the "tube" type with a diamond-shaped fragmentation mesh and an aerodynamic shaft with a vacuum chamber. At the same time, the semi-finished product of the shank is obtained from the bar stock for two hot stamping transitions (draft and flashing) on the press, and a measured tube is used as a blank for the casing shell, in which the right and then left spiral riffles are sequentially performed by pressing operations on hydraulic presses. After hard joining with the use of sealant of a semi-finished shank with a pipe billet, a copper lead belt is pressed into or welded into a special groove at their joint point, and then the final machining is performed by cutting the surface of the body and the lead belt. To increase the fragmentation of the tail of the housing on the side wall of the vacuum chamber perform radial slots.

The disadvantage of this method is the presence of labor-intensive technological operations associated with the implementation of the leading belt as a separate structural element, which significantly increases the cost of manufacturing the shell body as a whole. As shown by fragmentation tests, the presence of only cracks on the side wall of the rarefaction chamber is insufficient for efficient crushing of the tail of the projectile into fragments of acceptable mass.

A known method of manufacturing shells with a rhomboid fragmentation grid according to patent SU No. 473335, IPC VC 37/20, publ. 06/05/75 in bull. 22, the applicant is the Japanese company Sumitomo Metal Industries Limited. This method contains sequential reduction operations by pulling a pipe through a smaller diameter two dies of different diameters: from the workpiece to the semi-finished product and then to the caliber of the finished product. In this case, the tubular billet and the semi-finished product for the second operation of drawing through the dies are mounted on the spiral protrusions of short mandrels. During reduction, the dies fixed in the clips of the equipment bed are stationary, and the mandrel rotates freely, since their bearing rod is connected to the rotation mechanism. When dragging the grippers, the pipe is crimped in the die, rotating the mandrel, while spiral grooves — corrugations — are formed inside the pipe on its spiral projections. The presence of significant axial traction during radial flow of metal on the crimp of the pipe leads to crushing of the side surfaces of the formed corrugations and the appearance of burrs on their tops in the gap between the inner diameter of the workpiece and the outer diameter of the mandrel protrusions. Increased abrasive wear of the mandrels from the dynamic friction of the protrusions on the metal of the pipe pressed onto the mandrel during drawing increases the cost of production and the consumer cost of ammunition.

The closest analogue to the claimed invention is a method of manufacturing a shell of fragmentation ammunition according to patent RU No. 2171445, IPC F42B 12/24, B21K 21/06, B21C 37/20, publ. 07/27/2001.

This method includes performing on the inner surface of the shell semi-finished fragments of a rhombic profile by applying a grid of corrugations. This is ensured by successive operations of processing the metal of the shell by pressure in the cold state. In this case, before the reduction operation, the tubular workpiece is mounted on evenly spaced spiral protrusions of the central tool rod, having the opposite direction. The process of crimping the workpiece is carried out according to the scheme of the free radial flow of metal without a mandrel with a slightly variable wall thickness of the tubular workpiece.

Due to the fact that the reduction of the workpiece is carried out with a decrease in its diameter, its length inevitably increases. This operation proceeds with the gradual and “dry” enveloping of the spiral protrusions by the plastically deformable metal of the workpiece and the formation of a peculiar screw pair at the end of the technological cycle, in which the spiral protrusions of the tool bar and the workpiece are combined with an interference fit, the value of which is determined by the degree of deformation of the metal and the friction force of the contacting elements.

By virtue of the latter circumstance, the workpiece is screwed up from spiral protrusions under the action of great efforts, and, consequently, energy consumption. In addition, the dry relative sliding of the workpiece and the spiral protrusions during their separation causes longitudinal deformation of the lateral surfaces of the spiral grooves. This reduces the geometric accuracy and shape quality of the corrugations that perform the function of a gas wedge for detonation products, and worsens the crushing of the shell into a given number of fragments of the required mass. Dry dynamic insertion of spiral protrusions into the workpiece during the reduction process, as well as subsequent dry dynamic separation of the workpiece and spiral protrusions, reduces the life of expensive tool rods.

A disadvantage of this method is the fact that the blanks obtained with it with corrugations with a depth of 0.25-0.55 of its thickness are suitable only for the manufacture of fragmentation shells of rockets and mines, as well as ammunition with a stuffed or floating lead belt. In addition, as the results of the blasting of the hulls show, the mere depth of the riffles of the rhombic fragmentation mesh does not guarantee their planned crushing. An important factor for this is the mechanical properties of the body metal, in particular its hardness.

The task underlying the proposed invention is to develop a method for manufacturing a shell of a fragmentation shell from inexpensive and non-deficient steel with a lead belt directly made of its material, increase the durability of the tool to form a fragmentation mesh on the inner surface of the case, and improve its fragmentation during explosion.

The required technical result is achieved due to the fact that in the known method of manufacturing a shell of a fragmentation projectile with a leading belt, which includes cold reduction operations of a hollow workpiece such as a glass or pipe, which are carried out sequentially with the formation of spiral reefs on the inner surface of the workpiece by forcing the workpiece pre-installed removed on the tool rod with spiral projections of the opposite direction, through dies of different diameters the preform from the tool bar and its machining with the leading belt, new according to the invention is that a hollow preform of structural steel with a carbon content of up to 0.4% is used, the reduction of the preform is carried out using liquid or grease and creating around tool rod of an annular oil bath with a volume providing lubrication of the spiral protrusions of the tool rod gradually introduced into the workpiece, with the final opera The reduction is carried out to obtain a workpiece with an outer diameter exceeding the diameter of the leading girdle of the shell body by the amount of allowance for subsequent machining. Reduction is carried out with a degree of deformation that ensures the hardness of the outer layer of the workpiece after it is machined to the size of the driving belt - not more than 250 HV, and form corrugations with a depth of 0.215-0.249 of the wall thickness of the hollow workpiece.

The pipe-type billet reduction operations are carried out using an o-ring at the front end of the tool rod.

The workpiece after the first operation or the second reduction operation or the location on the workpiece of the drive belt before it is performed, or the drive belt is annealed.

Simultaneously with the reduction of a glass-type preform, fracture localizers are applied to its bottom.

In the manufacture of a shell for a fragmentation projectile with a rarefaction chamber, a stepped two-chamber blank of the glass type is used, in which the outer diameter of the stage forming the rarefaction chamber is not more than the diameter of the die used in the second reduction operation.

In the second step of reducing the workpiece, a tool bar is used, in which the angle at the apex of the spiral protrusions is less than the same angle of the tool bar used in the first step of reduction.

The invention is illustrated by drawings, which schematically depict:

- figure 1 - reduction of the workpiece type "glass";

- figure 2 - reduction of the workpiece type "pipe";

- figure 3 is a monolithic shell fragmentation shells with a rarefaction chamber in the context;

- figure 4 is a combined tool rod for the simultaneous formation of a fragmentation mesh in the shell and the bottom of the housing:

- figure 5 is a view of the front end of the combined tool rod.

In the proposed method, a blank 1 of the “glass” type (FIG. 1) or of the “pipe” type (FIG. 2) is used, made of structural steel with a carbon content of up to 0.4%. The manufacture of fragmentation shell blanks from these blanks begins with two operations of cold metal forming on a broaching machine, the tool assembly of which is schematically represented in FIGS. 1 and 2.

In the clip 2 of this assembly, a matrix 3 is fixed with a die 4 calibrated to the outside diameter of the machined tubular billet 4. The central tool rod 5 has conical spiral projections 6 of an estimated height on the lateral surface, which makes it possible to obtain the required jumper 7 in the blank 1 after reduction.

When reducing the workpiece 1 of the "glass" type (Fig. 1), the pusher 8 acts on the workpiece 1 through the tool rod 5. To reduce the workpiece 1 of the "pipe" type, an elastic ring 10 is installed on the front end 9 of the tool rod 5, and the axial force of the forcing is transmitted directly workpiece 1 from the pusher 11.

Before the deformation of the workpiece 1 of the "glass" or "pipe" type begins, liquid or grease 13 is supplied to its large chamber 12, the volume of which is determined from the condition of guaranteed lubrication of the spiral protrusions 6 introduced gradually into the workpiece 1.

In the vertical version of the tool assembly of the broaching machine, both liquid and grease are used, and in the horizontal version, grease is used. It is allowed to apply grease in two versions of the tool assembly of the broaching machine directly to the tool bar 5 before it is introduced into the cavity 12 of the workpiece 1.

The proposed method for manufacturing a shell of a fragmentation projectile (Fig. 3) with a leading belt 14 and a fragmentation mesh of a rhombic profile 15 formed by spiral flutes 16 of the opposite direction is carried out sequentially for two reduction operations in matrices 4 having different diameters and using different tool rods 5 with spiral projections 6. Moreover, after the second reduction, the diameter of the workpiece 1 exceeds the diameter of the leading belt 14 of the projectile by the amount of allowance for the last machining, and the depth 17 of the flutes 16 is 0.190-0.249 of the wall thickness 18 of the workpiece 1 after being crimped.

Depending on the carbon content in the workpiece, the degree of its deformation is chosen to ensure the hardness of the outer layer after machining to the size of the drive belt - not more than 250 HV. This ensures the planned destruction of the hull during detonation of the explosive, as well as barrel wear comparable to similar wear when firing shells with a copper lead belt.

The compression process of the workpiece 1 in the matrices 4 is accompanied by a gradual displacement of the lubricant 13 from the deformation zone to meet the forcing force and plentiful lubrication of the spiral protrusions introduced into the workpiece 6. Upon completion of the plastic deformation of the workpiece 1, the spiral protrusions 6 are immersed along the entire length in the oil bath 13. This the circumstance reduces the wear of the tool 5 both in the process of reducing the workpiece 1, and during its makeup from the spiral ledges 6, which means that the energy costs of the technology are reduced matic cycle. It also reduces the deformation of the side surfaces of the formed and formed corrugations 16, which increases the geometric accuracy of the fragmentation mesh 15, and therefore provides better conditions for stable destruction of the body during an explosion.

For fragmentation of the bottom into pieces of acceptable mass and size in the bottom lintel 19 of the billet 1 of the "glass" type, after the second reduction with a separate tool, the depressions 20 are made by direct pressing (Fig. 3). In order to increase labor productivity, these operations are combined using a combined tool (Fig. 4), equipped with both conical spiral protrusions 6 on the side surface of the tool rod 5 and inverted recesses 20 of the protrusions 21 on the front end 22 of the tool rod 5, for example, in the form of conical protrusions (figure 5).

In order to increase the ductility of the drive belt 14 and reduce wear of the barrel bore, the location of the drive belt 14 in the preform 1 or the lead belt 14 itself after its manufacture on the body or the preform 1 as a whole after its first or second reduction is subjected to additional annealing.

For the manufacture of a monolithic fragmentation shell with reduced aerodynamic drag, a stepped two-chamber blank of the “glass” type 1 is used (FIG. 1), in which the outer diameter 22 of the chamber 23 does not exceed the diameter of the die 4 for the second reduction. Compression of the workpiece 1 only in its larger diameter 24 reduces the force of failure through the die 4 and minimizes energy consumption.

The use of a tool rod 5 for the second reduction, in which the spiral protrusions 6 at the apex have an angle 25 smaller than the same angle at the first tool rod 5 by the “collapse” of the first riffles during the second reduction, allows to obtain a fragmentation mesh with equal left - and right-of-way localizers of destruction 16, performing the functions of a gas wedge for explosion products. This reduces the formation of fragments that are asymmetric, and consequently, fragments of various masses and poor aerodynamics, when the hull is destroyed.

Currently, using the proposed method, a fragmentation case for a full-time 30-mm grenade launcher GPD-30 is mass-produced. The body of this shot is performed by turning from a two-chamber billet of steel 20 with a carbon content of up to 0.24%. The workpiece with a fragmentation mesh has an outer diameter of 32 mm, which makes it possible to make a lead belt with a diameter of 31.05 mm on a 30 mm case, that is, with the smallest possible machining allowance. In this case, the blank shell has on the inner surface of the corrugation 1.15 mm deep and a wall 4.75 mm thick, that is, it is made with a ratio of these values as 0.242. After turning the workpiece, the size to the size of the drive belt, the hardness of its surface layer is not more than 250 HV. To reduce distortion of the fragmentation mesh during the reduction process, both liquid and grease are used. In the bottom of the workpiece by the method of plastic deformation, recesses are made.

The explosions in the armored chamber of the hulls obtained in accordance with the proposed method confirmed their destruction into fragments of the planned shape and mass. Firing tests also showed that the transition to a steel lead belt, that is, a belt made directly from the material of the grenade body and having a hardness not higher than 250 HV, does not reduce the barrel bore survivability compared to the copper lead belt previously used in grenade. In addition, this eliminated the scarce and expensive copper from the design, increased the load capacity of the leading belt, which is important for normal functioning in a worn barrel. The execution of the steel body directly with the leading belt reduced the complexity of its manufacture by ~ 12%.

An experimental verification of the proposed method with similar results was carried out on a 57-millimeter grenade high-explosive fragmentation VOF-57, the body of which was tested in two versions: structural steel 20 and structural alloy steel 30KhGSA (carbon content up to 0.34%).

The positive results of comprehensive research and full-scale testing of grenades in the caliber of 30- and 57-mm allow to guarantee the application of the proposed method in other calibers.

Information sources

1. Patent RU No. 2248514, IPC F41B 12/22.

2. Patent SU No. 473335, IPC V21C 37/20, publ. 06/05/1975.

3. Patent RU No. 2171445, IPC F12 / 24, V21K 21/06, V21C 37/20, publ. 07/27/2001 - a prototype.

Claims (6)

1. A method of manufacturing a shell of a fragmentation projectile with a leading belt, including cold reduction of a hollow workpiece such as a glass or pipe, which is carried out sequentially with the formation on the inner surface of the workpiece of a grid of spiral riffles by forcing the workpiece pre-installed on the tool rod with spiral protrusions in the opposite direction through dies of different diameters, removing the workpiece from the tool bar and machining it with a leading belt, characterized in that a hollow billet of structural steel with a carbon content of up to 0.4% is used, the reduction of the billet is carried out using liquid or grease and with the creation of a ring-shaped oil bath around the tool rod with a volume that lubricates the gradually introduced into the billet spiral protrusions of the tool rod, while the final reduction operation is carried out to obtain a workpiece with an outer diameter exceeding the diameter of traveling belt of the shell of the projectile by the amount of allowance for subsequent machining, reduction is carried out with a degree of deformation that ensures the hardness of the outer layer of the workpiece after it is machined to the size of the driving belt - not more than 250 HV, and form corrugations with a depth of 0.215-0.249 from the wall thickness of the hollow workpiece. 2. The method according to claim 1, characterized in that the operation of reducing the billet type pipe is carried out using a sealing ring at the front end of the tool rod. 3. The method according to claim 1, characterized in that the preform after the first operation or the second reduction operation or the location on the preform of the drive belt before it is executed, or the drive belt is annealed. 4. The method according to claim 1, characterized in that at the same time as reducing the billet type glass, fracture locators are applied to its bottom. 5. The method according to claim 1, characterized in that in the manufacture of the shell of the fragmentation projectile with the rarefaction chamber, a two-chamber stepped billet type is used, in which the outer diameter of the stage forming the rarefaction chamber is not more than the diameter of the die used in the second reduction operation. 6. The method according to claim 1, characterized in that in the second step of reducing the workpiece, a tool rod is used, the angle at the apex of the spiral protrusions is less than the same angle of the tool rod used in the first reduction operation.

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