WO1983003895A1

WO1983003895A1 - Armouring plate, particularly for lightened armouring

Info

Publication number: WO1983003895A1
Application number: PCT/FR1983/000085
Authority: WO
Inventors: Michel Pequignot
Original assignee: Michel Pequignot
Priority date: 1982-05-04
Filing date: 1983-05-02
Publication date: 1983-11-10
Also published as: DE3342776T1; FR2526535A1

Abstract

The armouring plate, having a metal weft (11), comprises at least one alveole (12) wherein a ceramic element (13) is arranged under sintering stress. Application to armouring, particularly lightened armouring, for the individual protection and protection of certain equipments.

Description

Armor plate, especially for light armor.

The present invention relates generally to the shielding, intended to protect projectiles or any other means of perforation, such as high temperature flames or plasmas for example, and it is aimed more particularly at the shielding plates usually used for the constitution of a lightened shielding.

It can be as well armor plates intended for the reinforcement of certain materials, and in particular certain aircraft, helicopters for example, for the protection of essential organs thereof, as well as those intended for the constitution of individual equipment, for example bullet-proof vests, for the protection of service personnel. These armor plates are traditionally made of metal, and more recently of ceramic. It is most often steel.

But, despite its price, which is higher, and lower mechanical characteristics, in particular with regard to the elastic limit, titanium is also frequently used, owing to the fact that, its density being much lower, almost half, compared to steel, it advantageously allows a significant gain in weight. As a corollary, and in particular for equipment for protection against small arms projectiles, res, it has already been proposed to use ceramic shielding plates.

By ceramic is meant here, in the usual way, a material compacted and sintered at high temperature. It can be, for example, alumina.

To date, such ceramic shielding plates are implemented individually, by simply being juxtaposed with each other, in the manner of the scales of a chain mail, for example within a support frame made of material. synthetic.

The use of ceramic for such shielding plates finds its justification in the fact that, in addition to a density lower than that of steel, and therefore a lesser weight, the ceramic has a high hardness, suitable for leading to a deflection. advantageous of the projectiles as well as of a crushing of these so as to reduce their perforation capacity. But in return, the ceramic is relatively fragile and brittle ”

Under the effects of a strong shock, a ceramic shielding plate can therefore dislocate, and therefore no longer offer any protection against a subsequent shock.

This is the reason why, as mentioned above, its application is in practice limited to protection with regard to small arms projectiles. The present invention, which is based on the observation that, when the ceramic is under stress, its brittleness is very significantly reduced, has for its object an armor plate advantageously making it possible to reconcile the advantages of metal and ceramic.

The armor plate according to the invention, which is made of metal, is generally characterized in that it comprises at least one cell in which a ceramic element is placed under hoop stress.

In practice, several ceramic elements are provided, which are distributed in one or more rows, in the manner of a mosaic, and / or in one or more layers, according to any network, for example alternated from one row to a other, and / or from one layer to another, the corresponding cells being either open, opening to the outside in full section or in reduced section on at least one of the faces of the plate, and possibly on the 'and both of them, be closed.

Together, the ceramic elements used have any configuration, and are for example cylindrical, conical or spherical. Anyway, being, according to the invention, under hoop stress, they have a high impact resistance, and are therefore advantageously free from the brittleness usually inherent in the ceramic which constitutes them. In other words, the metal frame in which they are located advantageously prevents their dislocation and their bursting in the event of an impact, because of the hoop stress that it applies to them. The armor plate according to the invention, of which, on the surface, the relative ceramic density can for example be of the order of 30 to 6θ%, therefore advantageously combines the mechanical characteristics of the metal which forms the screen with the qualities hardness, and lightness, ceramic enclosed in this frame, without being affected by the fragility of it.

In addition, taking into account that steel has an elastic limit higher than that of titanium, and that it is on this elastic limit on which depends in particular the maximum shrinking stress that it is possible to apply to the elements of ceramic implemented, it is advantageously possible, according to the invention, with a given hooping constraint, to implement, for the constitution of the metal frame suitable for receiving the ceramic elements, no longer titanium, but, if desired , steel.

Indeed, at a given hoop stress, and the other conditions being equal, the quantities of metal to be used are then less in steel than in titanium, and, as a result, the overall saving in material thus produced. at least to some extent compensates for the effects of higher density for steel than for titanium.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which: FIG. 1 is an elevation view of a shielding plate according to the invention. invention; Figure 2 is a cross-sectional view along the line II-II of Figure 1; Figure 3 shows, on a larger scale, a part of Figure 2 identified by an insert III thereon; Figures 4A, 4B are cross-sectional views, which, similar to that of Figure 3, illustrate a possible embodiment of the plate shielding according to the invention; Figures 5, 6, 7 are views similar to those of Figures 4 and each relate respectively to other possible embodiments for the armor plate according to the invention; Figures 8, 9, 10 and 11 are partial views similar to that of Figure 2 and each relate respectively to various alternative embodiments of the armor plate according to the invention; Figures 12A, 12B are views which, similar to those of Figures 4, relate to a possible embodiment for the armor plate shown in Figure 11; Figure 13 partially reproduces Figure 12B and relates to an alternative embodiment; FIG. 14 is a view similar to that of FIG. 1, for another alternative embodiment of the armor plate according to the invention ”

In general, and as illustrated in these figures, a shielding plate 10 according to the invention has a metal frame 11 and comprises, within this frame 11, at least one cell 12 in which is placed under hooping stress a ceramic element 13. In the embodiment more particularly shown in FIGS. 1 and 2, this armor plate 10 has a hexagonal contour, and it comprises several ceramic elements 13 distributed, in a single layer, according to several rows parallel to its sides, said ceramic elements 13 being alternated from one of these rows to the other.

A total of nineteen ceramic elements 13 are thus used in this embodiment " As a result, on the surface, in the mean median plane of the shielding plate 10 parallel to its faces, a ceramic density of between 30 and 6θ%, and for example close to 50%. In practice, in the embodiment more particularly shown in Figures 1 and 2, the ceramic elements 16 are cylindrical, and their cross section is circular.

Jointly, the cells 12 of the metal frame 11 in which they are arranged are also cylindrical, and of circular cross section, and these are open cells, said cells opening to the outside with full section on one and the other of the faces of the armor plate 10 which comprise them.

The metal frame 11 of the shielding plate 10 is preferably made of titanium.

But it could also be made of steel or any other metal or alloy having suitable mechanical characteristics.

Its cells 12 can be produced by machining, or by stamping for example.

Together, the ceramic elements 13 are preferably made of alumina, that is to say of aluminum oxide, but any other ceramic material may as well be envisaged.

They are preferably shaped in advance to their final geometry, even when they are pressed. As illustrated in FIGS. 4A, 4B, the positioning of the ceramic elements 13 in the cells 12 of the metal frame 11, and obtaining a hoop stress for these ceramic elements 13 "can be insured in the following manner, below, with reference to only one of these ceramic elements 13:

Initially, when cold, the cell 12 concerned has a diameter D1 slightly less than the diameter D2 of the corresponding ceramic element 13.

The difference in diameters can for example be between 0.1 and 1%.

The metal frame is then heated, to a temperature of the order of 600 to 900 ° C. for example, sufficient, in any case, so that, due to the thermal expansion which results therefrom, the diameter D'l of the cell 12 is then at least equal to that D2 of the ceramic element 13, and preferably very slightly higher, while, jointly, this is preferably left at ordinary temperature "

The ceramic element 13 is then introduced, for example by the press, into the cell 12, FIG. 4B, and the assembly is cooled. Due to the shrinkage of the metal on cooling, joined to the fact that the metal has a coefficient of thermal expansion greater than that of ceramic, and for information it will be specified here that the coefficient of thermal expansion of titanium is of the order of 0 , 84 x 10 ^-5 / 0 ° C, that of steel of the order of 1.7 x 10 ^-5 and that of ceramic of the order of 0.65 x 10 ^-5 , the element in ceramic 13 is, upon cooling, the subject of an annular hoop stress on the part of the metal frame 11 which encloses it. This hooping stress, which will preferably be as high as possible with regard to the material used, depends in particular on the elastic limit of the metal constituting the frame 11, and on the annular clearance which has allowed the introduction of the element into ceramic 13 in the cell 12 after heating of the metal frame 11.

By leaving this ceramic element 13 cold during this introduction, advantage is taken of the differences existing between the coefficients of thermal expansion of the ceramic and of the metal. Of course, the above process can be applied individually to each of the ceramic elements 13 to be used, or, simultaneously, to all or part of them.

According to a variant embodiment not shown, these ceramic elements 13, instead of being strictly cylindrical, are slightly frustoconical. Besides that, after their pressing, their demolding is facilitated, their positioning in the cells 12 is also advantageously facilitated, the corresponding adjustment being able to be made less precisely. According to the variant of implementation illustrated in FIG. 5, obtaining a hoop stress can be ensured by hot brazing.

In such a case, and as shown, each ceramic element 13 is cold in the corresponding cell 12 of the metal frame 11 itself left cold, a sufficient annular clearance being provided for this purpose between such an element ceramic 13 and such a cell 12, and, in the form for example of a ring, the solder 15 is placed on the metal frame 11, in line with said annular clearance.

The assembly is then brought to hot, which, by fusion, leads the solder 15 to fill the annular clearance between the ceramic element 13 and the cell 12, clearance which, due to the differences between the coefficients corresponding thermal expansion, has increased compared to what it was cold.

On cooling, a brazing metal sheath is annularly interposed in a rigid and rigid manner between the ceramic element 13 and its cell 12, so that, as before, due to the differences between the coefficients of thermal expansion of the two materials in question, the ceramic element 13 is the object, through said sheath, of an annular hoop stress on the part of the metal frame 11 which encloses it.

According to an implementation variant not shown, the positioning of the ceramic element 13 in the cell 12 can also, as previously, be done cold, and after, as previously, the assembly has been brought to a suitable temperature, the cell 12 in which the ceramic element 13 is located is closed annularly thereon, by pressing and / or stamping, until it comes into intimate contact with this ceramic element 13.

As before, on cooling, this is therefore subject to an annular hoop stress.

According to the variant of implementation illustrated in FIG. 6, the ceramic element 13 is put into place in the metal frame 11 by force, by press forging of this metal frame 11 carried for this purpose at a sufficient temperature, the ceramic element 13, which is cold, playing in this respect the role of a punch and forming itself, as it penetrates into the metal frame 11, the cell 12 in which it must be placed "

Upon cooling, and as before, it is therefore subject to an annular fretta constraint ge.

According to the variant of implementation illustrated by FIG. 7, the ceramic element 13 forms, in a mold 18, an insert around which the metal frame 11 is overmolded.

In the embodiment more particularly represented in FIGS. 1 and 2, the height of a ceramic element 13 _", that is to say its dimension perpendicular to the faces of the armor plate 10, which, in this embodiment, is equal to the thickness of the corresponding metal frame 11, is of the order of magnitude of its diameter "

As a variant, in FIG. 8, it can be very much less than this diameter.

According to the variant of FIG. 9, the cells 12 are blind, these cells opening to the outside only on one of the faces of the corresponding shielding plate 10. According to the variant embodiment illustrated in FIG. 10, two layers of ceramic element 13 are provided, the corresponding cells 12 each opening out respectively on the corresponding face of the shielding plate 10 concerned. According to the variant embodiment illustrated in FIG. 11, the cells 12 can be completely closed.

As illustrated in FIG. 12A, these cells 12 can initially be blind cells, into which the ceramic elements 13 are introduced, and which, then, are closed by forming and / or stamping, as illustrated by the arrows F in Figure 12B.

As shown in Figure 11, the closing of alveoli 12 thus insured may be total "

As a variant, in Figure 13, it can leave an opening 19, so that the cells 12 then open to the outside in a reduced section. Preferably, and as illustrated in FIG. 11, from one layer to another, the ceramic elements 13 are alternated, so that, perpendicular to the faces of the shielding plate 10 concerned, there is in projection at least one ceramic element that 13 and at any point of this armor plate 10 "In the embodiment shown in FIGS. 11 to 13, the ceramic elements 13 used are spherical and therefore take the form simple marbles. But, as before, they might as well be cylindrical or slightly tapered.

The geometric configuration of the ceramic elements 13 is, moreover, arbitrary, this configuration being able to be provided so as to ensure, if possible, a deflection of the incoming projectiles, for diversion of these on a neighboring ceramic element 13.

From this point of view, a spherical or frustoconical shape is particularly advantageous. Likewise, the network according to which the various ceramic elements 13 used within a single layer are distributed may be arbitrary.

As illustrated for example in FIG. 14, which relates to a shielding plate 10 of rectangular outline, this network can itself be an orthogonal network.

The present invention is moreover not limited to the various embodiments shown, nor to the various embodiments described and illustrated, but extends to any variant.

Claims

CLAIMS 1. Metal shielding plate, characterized in that it comprises at least one cell (12) in which a ceramic element (13) is arranged under hoop stress.

2. Armor plate according to claim 1, characterized in that it comprises several ceramic elements (13) distributed in at least one row and / or in at least one layer ”

3. Armor plate according to claim 2, characterized in that it comprises several rows and / or several layers of ceramic elements (13).

4. Armor plate according to claim 3, characterized in that the ceramic elements (13) are alternated from one row to another and / or from one layer to another.

5. Armor plate according to any one of claims l to 4, characterized in that the ceramic elements (13) are cylindrical and have for example a circular cross section.

6. Armor plate according to any one of claims 1 to 4, characterized in that the ceramic elements (13) are spherical.

7 »armor plate according to any one of claims 1 to 6, characterized in that at least one of the cells (12) is open, said cell opening to the outside on at least one of the faces of the plate.

8. Armor plate according to claim 7, characterized in that at least one of the cells (12) opens out onto one and the other of the faces of the plate.

9. Armor plate according to any one of claims 7, 8, characterized in that at least one of the cells (12) is cylindrical and the opening through which it opens to the outside on one face of the plate is full section.

10. Armor plate according to any one of claims 1 to 6, characterized in that at least one of the cells (12) is closed.