GB2385906A

GB2385906A - Projectiles

Info

Publication number: GB2385906A
Application number: GB8624538A
Authority: GB
Inventors: Ronald Michael Henson
Original assignee: English Electric Co Ltd; GEC Alsthom Ltd
Current assignee: GE Power UK
Priority date: 1985-10-11
Filing date: 1986-10-10
Publication date: 2003-09-03
Anticipated expiration: 2006-10-10
Also published as: GB2385906B; GB8624538D0; SE8703070D0; GB8525090D0

Abstract

The invention concerns projectiles of the kind fired by weapons with rifled barrels, i.e. bullets, cannon shells etc. The projectile comprises a composite core which consists of a steel section 2 and a ceramic section 11 intimately connected to a soft sheath 3. Various structures are shown. An incendiary material may be included with the core. Preferred ceramics are alumina, silicon nitride, or a solid solution of the two.

Description

PROJECTILES This invention relates to projectiles of the kind fired by weapons with rifled barrels, i. e. , bullets, cannon shells etc.

Conventional bullets comprise a cartridge (usually of brass) containing the propellant explosive and detonator. The cartridge is pressed on to the rear end of the projectile which consists of a hard metal (hardened steel for example) member, sheathed in an envelope of soft'gilding metal'which usually has a substantial copper content. Incendiary bullets have a gap at the forward end within the sheath for incendiary material. Such a projectile is shown in Figure 1 of the accompanying drawings, in which the hard metal member 1 is contained by the soft metal sheath 3, the incendiary material being referenced 5.

The sheath 3 is preformed and pressed on to the core 1, the open rear end of the sheath being turned in and pressed into engagement with a lead seal 7. An indented knurled ring 9 provides a fixing position for the cartridge (not shown), and a further knurled ring (not shown) may be used for identification of the type of bullet.

In use, the soft metal sheath is deformed into the rifling grooves of the gun barrel to provide a purchase for rotation of the projectile, and the soft metal sheath also serves to seal the barrel and give maximum effect to the explosive charge.

Attempts have been made to improve the armour penetration properties of bullets by using a tungsten core, tungsten being harder, more refractory and heavier than hardened steel. The desired increased penetration is achieved but at a greatly increased cost.

According to the present invention, an axially symmetric

projectile comprising a hard core and a soft metal sheath and adapted for firing from a rifled barrel, includes a ceramic member, to which the soft metal sheath is directly or indirectly intimately bound. There is preferably included a hard metal member fixed to the ceramic member.

The ceramic member may enclose at least part or all of the hard metal member.

The ceramic member may be mounted on a circumferential recess in the hard metal member, the outer surface of the ceramic conforming to the outer surface of the core.

The ceramic member may have a cylindrical inner surface engaging a complementary surface of the hard metal member, the ceramic member extending from the position at which the recess intercepts the outer surface of the hard metal member backwards to a shoulder in the hard metal member.

The circumferential recess may be formed between two parts of the hard metal member one of the two parts having a male member extending into an axial recess in the other of the two parts, the male member being longer than the axial recess.

The ceramic member may be one of two or more ceramic members all embracing the male member, a respective metal ring conforming to the inner and outer surfaces of the ceramic members being positioned between each pair of adjacent ceramic members.

The ceramic member may extend at least partly around the back of the hard metal member.

The hard metal member may have a tapered rear portion which mates with the bore of the ceramic member, the forward end of the tapered portion terminating in a shoulder which provides an abutment for the forward end of the ceramic member.

The ceramic member may have a stepped cylindrical bore, the rearward portion of the bore being of axial length comparable with the wall thickness of the greater part of the ceramic member length.

The ceramic member may form the forward end of the projectile and may be fitted to the hard metal member by an axial male/female connection consisting of cylindrical and transverse plane surfaces.

The hard metal member may enclose part or all of the ceramic member.

The hard metal member may be mounted in a circumferential recess in the ceramic member, the outer surface of the hard metal member conforming to the outer surface of the core.

The hard metal member may have a cylindrical inner surface engaging a complementary surface of the ceramic member, the hard metal member extending from the position at which the recess intercepts the outer surface of the core backward to a shoulder in the ceramic member.

The soft metal sheath may be intimately bound to the outer surface of the hard metal member which in turn is intimately fixed to the ceramic member.

At least part of the ceramic member may be metallised and intimately bound to the soft metal sheath.

The ceramic member and the hard metal member are preferably intimately fixed together by metallising of at least part of the interengaging surfaces and brazing, soldering, shrink fitting or otherwise intimately fixing the two members together by way of this metallised part.

In a particular extreme embodiment a ceramic member is metallised over substantially its whole surface and directly intimately connected with the soft metal sheath.

A number of embodiments of projectile in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 is a sectional elevation of a conventional incendiary bullet; Figures 2 to 9 show sectional elevations of various constructions in accordance with the invention.

It will be appreciated that in all cases the projectile is axially symmetric to ensure a stable flight path.

Referring to the drawings, Figure 2 shows the core of a projectile, i. e. , without any incendiary content and without the soft metal sheath 3. If in fact there is no incendiary content a void may be left in the forward end of the sheath.

The projectile core of Figure 2 comprises a ceramic member 11 of annular, or rather, tubular, form, mounted in a circumferential recess in a hardened steel member 1. The inner surface 13 of the ceramic member is cylindrical, as is the mating surface of the

member 1. The ceramic member extends from the point 15 at which the recess intercepts the outer contour of the metal member back to a shoulder 17 of the metal member. This shoulder provides an abutment surface between the ceramic member 11 and the hard metal member 1.

The length of the ceramic member may be from near zero to the whole length of the core.

The diameter of the metal spigot 19 may be varied between zero and a value such that the ceramic member is merely a coating on the metal member.

The important requirement for successful operation of such a projectile is that the soft metal sheath, the hard metal member and the ceramic member do not become detached in the gun barrel or in flight. It is therefore necessary that there is an intimately binding connection between the sheath and the ceramic member either directly or by way of the hard metal member. The sheath can be brazed on to the metal member and if there is sufficient metal surface exposed this will provide an adequate bonding to the ceramic member if the latter is in turn fixed by bonding (brazing etc. ) or, as will be seen, by positive structural fixing, to the metal member.

In the construction shown in Figure 2 the ceramic member may be brazed to the hard metal member either at the cylindrical surface 13 or the abutment surface of the shoulder 17, or at both. In brazing the ceramic it is necessary first to'metallise'its surface, by coating it with, for example, molybdenum, to enable the braze material to'take'.

If the ceramic is to be bonded to the soft metal sheath directly, it is also necessary that its outer surface be similarly metallised.

The ceramic in question may be, for example, alumina, silicon nitride, or a solid solution of the two. Its precise formulation may be chosen to provide a good thermal match with the steel component for brazing purposes and may also be chosen to provide low thermal shock resistance. This characteristic produces a shattering of the ceramic following the heat produced on impact and penetration of armour.

The increased penetration properties of such a composite core bullet may be due to the higher rotation speeds imparted to the lighter bullet by the barrel rifling, or to the hard and abrasive

nature of the ceramic itself, or to a combination of the two.

Figures 3 (a) and 3 (b) show complementary modifications of the composite core structure.

In Figure 3 (a) the ceramic member 11 is of annular form positioned in a recess formed between the parts (21 and 23) of a two-part metal member. One of the two parts (21) has a cylindrical male member 25, i. e. , a spigot, extending into a borehole in the other part 23. The spigot is longer than the borehole so that an annular recess is formed when the spigot is pushed fully home into the borehole.

The two parts of the metal member are brazed together where they are in contact. The ceramic member may be metallised and brazed to the metal parts at its end (i. e. , transverse) surfaces or at its inner cylindrical surface, or at both.

Alternatively, since in this construction the ceramic member is positively trapped, the direct intimate bonding with the metal member may be omitted.

The soft metal sheath is of course bonded by brazing or otherwise to the outer surfaces of the metal member or the ceramic according to their extents, or to both. The diameter of the spigot 25 and the axial length of the ceramic member may be varied over substantially the full range. With zero diameter spigot the ceramic member would of course have to be brazed to the two parts of the metal member.

Figure 3 (b) shows a similar but inverted arrangement in which the male and female roles are reversed, the spigot 25 being on the rear part of the metal member. The construction is otherwise similar.

Figure 4 shows a further variation of the consruction of Figure 3 (a), in which the single ceramic member is replaced by two ceramic rings, 27 and 29 and a (sandwiched) metal ring 31. Again the two parts 21 and 23 of the metal member are brazed together but the various ceramic rings and metal ring 31 may be left un-bonded.

There may be a series of alternate ceramic and metal rings.

In each case the outer surfaces of the ceramic and metal rings conform to the contour of the core.

Figure 5 shows a construction in which the forward end of the composite core is formed by a ceramic member 32 which has an axial

male extension, i. e., spigot 33, engaging a borehole in the metal component 34. The spigot 33 has cylindrical and plane surfaces and they may be metallised and brazed to the metal member. Alernatively the plane, transverse surface of the ceramic member 32 around the spigot 33 may be metallised and brazed to the abutting surface of the metal member 34.

The diameter of the spigot 33 may be varied from zero to the full diameter of the core, these extremes producing of course the same result. The spigot length may be varied up to the length of the metal member.

Figure 6 shows a construction in which the forward end of the projectile is formed by the hard metal member 36, the rear end of the metal member forming a tapered spigot 35 the forward end or'root' of which forms an abutment shoulder for the ceramic member 37. The tapered surface of the latter member is metallised and brazed to the tapered spigot surface.

The length of the ceramic 37 may be varied and the outer surface may be metallised for bonding with the soft metal sheath depending upon the relative surface areas of the ceramic and metal members.

In Figure 7 the situation is largely reversed, the metal member 39 largely enclosing the ceramic member 41. The metal component 39 may be considered as being mounted in a (very long) circumferential recess in the ceramic member 41. Alternatively the latter comprises an inner cylindrical component with a rear end flange, the tubular metal member 39 embracing the ceramic member 41.

The metal core component extends back from the forward end to engage the shoulder formed by the ceramic flange. The thickness of the latter will determine the length of the metal component. Brazing of the two components may extend along the cylindrical surfaces or over the flange surface or both. The rear face of the flange may be metallised for bonding with the sheath.

Figures 8 and 9 show similar designs but inverted with respect to metal and ceramic components. In Figure 8, the hard metal component 43 is of full length and is encased by a ceramic member 45 with a cylindrical bore. The latter is stepped at its rear end to a smaller bore diameter. The axial extent of the rear end step is comparable with the wall thickness of the main part of the ceramic

member. The two components may be brazed together, with the necessary metallising, either along the longer cylindrical surface or the shorter rear one. Alternatively, in the cases where the hard metal surrounds the ceramic, the hard metal member may be a shrink fit on the ceramic. Where brazing is mentioned as the method of bonding the hard metal to the metallised ceramic it will be clear that soldering between the hard metal and the metallised ceramic, with an intervening 'thinning'coating, is an alternative.

The outer surface of the ceramic member 45 is metallised in this case (in which ceramic constitutes the main part of the outer surface) for bonding with the soft metal sheath.

In Figure 9 the construction is reversed. The small extent of outer ceramic surface will not warrant metallising.

Although the core is illustrated in the drawings as being a snug fit within the sheath, and without the incendiary material such as shown in Figure 1, it will be appreciated that incendiary material may be included. In fact it is contemplated that in practice the sheath may be a standard size for a particular core size and may have a forward end filling of incendiary material, non-incendiary flux material, or merely a void, as required.

The extreme versions of the above construction range from an all metal member with a ceramic coating, to an all ceramic member metallised for bonding to the sheath. In every case however, the sheath is intimately bonded to at least part of the underlying surface be it ceramic or metal.

The resulting construction provides an armour piercing projectile which is more effective than conventional steel designs while being cheaper than tungsten core designs.

Claims

CLAIMS 1. An axially symmetric projectile comprising a hard core and a soft metal sheath and adapted for firing from a rifled barrel, the hard core comprising a ceramic member to which said soft metal sheath is directly or indirectly intimately bound.
2. A projectile according to Claim 1 including a hard metal member fixed to said ceramic member.
3. A projectile according to Claim 2 wherein said ceramic member encloses at least part of said hard metal member.
4. A projectile according to Claim 3 wherein said ceramic member is mounted on a circumferential recess in the hard metal member, the outer surface of the ceramic conforming to the outer surface of the core.
5. A projectile according to Claim 4, wherein said ceramic member has a cylindrical inner surface engaging a complementary surface of said hard metal member, the ceramic member extending from the position at which the recess intercepts the outer surface of the hard metal member backwards to a shoulder in the hard metal member.
6. A projectile according to Claim 4, wherein said circumferential recess is formed between two parts of the hard metal member one of said two parts having a male member extending into an axial recess in the other of said two parts, the male member being longer than the axial recess.
7. A projectile according to Claim 6, wherein said ceramic member is one of two or more ceramic members all embracing said male member, a respective metal ring conforming to the inner and outer surfaces of the ceramic members being positioned between each pair of adjacent ceramic members.
8. A projectile according to Claim 3, wherein said ceramic member extends at least partly around the back of the hard metal member.
9. A projectile according to Claim 8, wherein said hard metal member has a tapered rear portion which mates with the bore of the ceramic member, the forward end of the tapered portion terminating in a shoulder which provides an abutment for the forward end of the ceramic member.
10. A projectile according to Claim 8, wherein said ceramic member has a stepped cylindrical bore, the rearward portion of the

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bore being of axial length comparable with the wall thickness of the greater part of the ceramic member length.
11. A projectile according to Claim 2, wherein the ceramic member forms the forward end of the projectile and is fitted to the hard metal member by an axial male/female connection consisting of cylindrical and transverse plane surfaces.
12. A projectile according to Claim 2, wherein said hard metal member encloses part or all of said ceramic member.
13. A projectile according to Claim 12, wherein said hard metal member is mounted in a circumferential recess in the ceramic member, the outer surface of the hard metal member conforming to the outer surface of the core.
14. A projectile substantially as hereinbefore described with reference to any of Figures 2 to 9 of the accompanying drawings.

14. A projectile according to Claim 12 wherein said hard metal member has a cylindrical inner surface engaging a complementary surface of said ceramic member, the hard metal member extending from the position at which the recess intercepts the outer surface of the core backwards to a shoulder in the ceramic member.

15. A projectile according to any of Claims 4 to 7 and 11 to 14, wherein said soft metal sheath is intimately bound to the outer surface of said hard metal member which in turn is intimately fixed to said ceramic member.

16. A projectile according to any of Claims 3 to 11,13 and 14, wherein at least part of the outer surface of the ceramic member is metallised and is intimately bound to said soft metal sheath.

17. A projectile according to any of Claims 2 to 16, wherein the ceramic member and the hard metal member are intimately fixed together by metallising of at least part of the interengaging surfaces and brazing, soldering, shrink fitting, or otherwise intimately fixing the two members together by way of this metallised part.

18. A projectile according to Claim 1 comprising a ceramic member metallised over substantially its whole surface and directly intimately connected with said soft metal sheath.

19. A projectile substantially as hereinbefore described with reference to any of Figures 2 to 9 of the accompanying drawings.

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Amendments to the claims have been filed as follows 1. An axially symmetric projectile comprising a hard core and a soft metal sheath and adapted for firing from a rifled barrel, the hard core comprising a ceramic member and a hard metal member, wherein the ceramic member and the hard metal member are intimately fixed together by metallising of at least part of the interengaging surfaces and brazing, soldering, shrink fitting, or otherwise intimately fixing the two members together by way of this metallised part, and wherein said soft metal sheath is intimately bound to at least one of said ceramic member and said hard metal member.

2. A projectile according to Claim 1 wherein said ceramic member encloses at least part of said hard metal member.

3. A projectile according to Claim 2 wherein said ceramic member is mounted on a circumferential recess in the hard metal member, the outer surface of the ceramic conforming to the outer surface of the core.

4. A projectile according to Claim 3, wherein said ceramic member has a cylindrical inner surface engaging a complementary surface of said hard metal member, the ceramic member extending from the position at which the recess intercepts the outer surface of the hard metal member backwards to a shoulder in the hard metal member.

5. A projectile according to Claim 3, wherein said circumferential recess is formed between two parts of the hard metal member one of said two parts having a male member extending into an axial recess in the other of said two parts, the male member being longer than the axial recess.

6. A projectile according to Claim 5, wherein said ceramic member is one of two or more ceramic members all embracing said male member, a respective metal ring conforming to the inner and outer surfaces of the ceramic members being positioned between each pair of adjacent ceramic members.

7. A projectile according to Claim 2, wherein said ceramic member extends at least partly around the back of the hard metal member.

8. A projectile according to Claim 7, wherein said hard metal member has a tapered rear portion which mates with the bore of the

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ceramic member, the forward end of the tapered portion terminating in a shoulder which provides an abutment for the forward end of the

ceramic member.

9. A projectile according to Claim 7, wherein said ceramic member has a stepped cylindrical bore, the rearward portion of the bore being of axial length comparable with the wall thickness of the greater part of the ceramic member length.

10. A projectile according to Claim 1, wherein the ceramic member forms the forward end of the projectile and is fitted to the hard metal member by an axial male/female connection consisting of cylindrical and transverse plane surfaces.

11. A projectile according to Claim 1, wherein said hard metal member encloses part or all of said ceramic member.

12. A projectile according to Claim 11, wherein said hard metal member is mounted in a circumferential recess in the ceramic member, the outer surface of the hard metal member conforming to the outer surface of the core.

13. A projectile according to Claim 11, wherein said hard metal member has a cylindrical inner surface engaging a complementary surface of said ceramic member, the hard metal member extending from the position at which the recess intercepts the outer surface of the core backwards to a shoulder in the ceramic member.