GB2326222A

GB2326222A - Obturation system for artillery weapons

Info

Publication number: GB2326222A
Application number: GB9812155A
Authority: GB
Inventors: Gert Schlenkert; Helmut Isgen; Rolf Bartolles; Seidlitz Henning Von
Original assignee: Rheinmetall Industrie AG
Current assignee: Rheinmetall Industrie AG
Priority date: 1997-06-12
Filing date: 1998-06-05
Publication date: 1998-12-16
Anticipated expiration: 2018-06-05
Also published as: ITMI981259A1; DE19724847B4; JPH1114297A; NO981487D0; DE19724847A1; GB9812155D0; NL1009393C2; NO981487L; GB2326222B

Abstract

An obturation system for artillery weapons has a barrel base ring (6), a obturator ring (4) and a breech insert (3) forming part of breech (2). To avoid escape of hot propulsion gases between the obturator ring and the breech insert even under high pressures and firing frequencies, at least the surface zones of the components (3,4,6) of the obturator system are provided with a coating (7,8 and 9) of a mechanically resistant material or a corrosion resisting and wear-proof metal or a metal alloy or ceramic.

Description

TITLE 1 Obturation System for Artillery Weapons 2326222 This invention

relates to an obturation system for artillery weapons.

this invention also relates to a method for the production of an obturator system.

An obturation system for artillery weapons is known from DE 40 06 215 Al, which mainly comprises a base ring, an obturator ring and a breach insert which is intended to ensure that the rear end of the barrel of the weapon is sealed off against the propulsive gases occurring during the firing operation. In view of the high stresses involved the components of the obturation system are usually made of steel.

In contrast to cartidged ammunition, with which the relevant cartridge case as a rule only has to seal off the rear of the barrel against propulsion gases once, the sealing in the case of artillery weapons is provided by the obturation system for a number of firing operations. As the components of the obturation system are directly exposed to the propulsion gases and residues, they are subjected to high thermal corrosive and abrasive stresses and in addition, in the case of blow through (escape of the hot propellant charge gases at certain separate places between the obturation ring and the breech insert), to erosion as a result of the gases and residues. The surfaces of the components of the obturation system thus may suffer serious corrosion and abrasion, so that within a relatively short time a pitted surface is produced to which the 1 2 charge residues, firmly adhere, making blow-through more liable to occur.

An object of this invention is to provide an obturation system for a weapon which will largely overcome surface deformation of components and thus blow-through, even under high pressures and rapid firing rates.

Another object is to provide a method for the production of such an obturation system.

According to this invention there is provided an obturation system for artillery weapons having a barrel with a base ring, an obturator ring and a breech closure insert, wherein at least one of the components of the obturation system is provided on a surface facing the barrel combustion gases, with at least one layer comprising a mechanically resistant material or a corrosion resisting and wear-proof metal or a metal alloy or ceramic.

According to this invention there is also provided a method for the production of an obturation system, in which method the coating on the relevant component of the obturation system is effected using a vapour deposition of the coating materials.

The principle on which the invention is primarily based is that the components of the obturation system, at least on their surface zones are coated with a suitable material for forming the sealing surfaces. The coating materials found suitable are mechanically resistant materials such as eh-romium nitride (CrN), titanium nitride (TiN), titanium ca"nitride (TiCN), titanium aluminium nitride or a combination of these materials.

The obturation system according to this invention offers the considerable advantage of noticeably improving the durability and 3 reliability of the system by comparison with obturation systems already known, so that the time-consuming operation of changing the base ring andlor the breech insert is very seldom necessary.

Furthermore, the relatively thin coating (2-5pLm) obviates problems connected with the fit.

Finally, it has been found that the coating of mechanically resistant material are easy to clean and suffer no abrasion from the cleaning process.

The operation of coating the surface of each part of the obturation system is advantageously performed by depositing the coating materials by a vapour method. Coating techniques of this kind are also known as PVD (physical vapour deposition) or CVID (chemical vapour deposition).

the mechanically resistant materials, metals, alloys or ceramics are deposited at temperatures of between 20011C and 6500C.

These processes known, see for example K. Reichel, "Coatings from the Vapour Phase", H.D. Steffens, and W. Brandi, "Modem Coating Processes", published by DGM 1992, pp. 225-228. Steels already hardened and tempered can be coated without hardness loss or distortion. This method involves no alteration of the base material.

In one advantageous version of the invention the relevant component of the obturation system is provided with a double coating.

For this purpose the! base material is first of all coated with CrN and Ifien with-TiN. This provides a simple means of deciding when the corresponding parts of the obturation system have to be removed and replaced; for when the gold-like TiN layer has eventually worn away the 4 chromium-coloured basic layer underneath becomes visible. Although this basic layer Will take over the function of the top layer for a certain period the advisability of removing and replacing the worn part of the obturation system, for example the obturator ring, is indicated by the 0.5 difference in colouring.

The combination of CrN and TiN coatings not only serves as a visual wear indicator but also ensures more satisfactory over-all properties. The CrN layer mainly functions to provide protection against corrosion, accompanied by a certain degree of protection against abrasion likewise. The TiN layer renders the components of the obturation system still more resistant to abrasion.

Further features and advantages of this invention are described in conjunction with examples for the performance and by reference to the drawings, wherein:

Figure I shows a longitudinal section through part of the breech end of a barrel, and Figure 2 shows an enlarged view of the circled portion 11 shown in Figure 1 Referring to the drawings, Figure 1 contains a barrel 1 on the rear end of which is mounted a breech wedge 2. The breech wedge 2 is shown in the closed position and includes a breech insert 3. The latter forms the locating surface of a rectangular shaped obturator ring 4 which is mounted in a recess 5 associated with a base ring 6 and connected in turn with the barrel 1 of the weapon. The way in which this obturation system functions is known and is described in detail in DE 40 06 215 referred to Previously.

In contrast to the obturation system disclosed in DE 40 06 215 the system according to this invention provides that the breech insert 3, the obturator ring 4 and the base ring 6 are provided with a coating 2-5gm thick and comprising chromium nitride, titanium nitride, titanium carbonitride or a combination of these. materials. The corresponding coatings are shown in broken lines in Figure 2 and are referenced 7, 8 and 9.

It has proved particularly advantageous for the coating of the surfaces of the relevant component of the obturation system to be carried out by either the PVD or the CVID method. In such processes steels already hardened and tempered can likewise be coated without hardness losses and warping and without any change in the base material.

This invention is not confined to the example described in the foregoing. It has been found advantageous for instance, to provide a double coating instead of only one coating on the obturation component concerned. For this purpose the base material in question, for example that of the obturator ring, is first provided with a CrN layer, to which a TiN layer is then added. This measure, as already explained, provides a simple means of determining the time at which the relevant component of the obturation system should be removed and replaced, because the two coatings differ in colour.

Suitable coating materials include not only mechanically resistant materials but also metals, alloys and ceramics, insofar as they ensure the protection of the components of the obturation system against corrosion 6 and wear. Examples of corrosion resisting materials are chromium, gold, tungsten, niobium, tantalum and their alloys, while the most suitable ceramics are zirconium oxide and aluminium oxide.

7

Claims

Obturation system for artillery weapons having a barrel with a base ring, an obturator ring and a breech closure insert, wherein at least one of the components of the obturation system is provided on a surface facing the barrel combustion gases, with at least one layer comprising a mechanically resistant material or a corrosion resisting and wear-proof metal or a metal alloy or ceramic.
2. Obturation system according to Claim 1, wherein the mechanically resistant material comprises chromium nitride, titanium nitride, titanium carbonithde, titanium aluminium nitride or a combination thereof.
3. Obturation system in accordance with Claim 2, wherein the relevant component of the obturation system is provided with at least two coatings, one on the other, the first coating which is nearer to the uncoated component of the obturation system comprising chromium nitride, the adjacent second or outer coating comprising titanium nitride.
4. Obturation system in accordance with any one of Claims 1 to 3, wherein the thickness of the coating provided on the relevant component of the obturation system is between 2 and 5gm.
5. Method for the production of an obturation system in accordance 25 with any one of Claims 1 to 4, in which method the coating on the relevant 8 component of the obturation system is effected using a vapour deposition of the coating materials.
6. Method in accordance with Claim 5, wherein the deposition of the mechanically resistant materials, metals, alloys or ceramics is effected at temperatures of between 2000C and 6500C.
7. An obturation system for a barrel weapon and a weapon incorporating such a system constructed and arranged to function as described herein and exemplified with reference to the drawings.
8. A method for forming or producing an obturation system for a barrel weapon as described herein and exemplified with reference to the drawings.