EP3992569B1 - Protective plate - Google Patents

Description

The invention relates to a protective plate according to the preamble of the first patent claim.

Such protective plates are used, for example, as ballistic protection, for example in special protection vehicles such as armored cars, military vehicles and personal protection equipment.

For conventional body components, especially those with high pedestrian protection requirements, methods for generating a regular

Vault structure used by rolling, embossing or hydroforming. Such components are mainly used in the front area of passenger cars (e.g. bonnet) to support the smooth outer structure. These should improve the flexural rigidity of the component through the spatial structure and contribute to a defined deformation in the event of an accident.

These processes are used exclusively for the production of thin sheet metal parts with low strength. DE 199 28 370 A1 discloses a protective panel according to the preamble of claim 1.

From the pamphlet DE 103 39 069 A1 a press-hardened component with a vault structure is known, which is in particular a structural component of a vehicle body which is intended to have increased local rigidity. In order to achieve high component strength, the component is made of high-strength steel. A hot forming process is used to form the three-dimensional component shape, during which the component is hardened. During this hot forming process, a local stiffness-increasing deformation structure is formed into the component, which consists of a periodic lattice of adjacent cells. In this solution, the deformation structure preferably consists of a periodic pattern of flat hexagonal bumps, which are provided with fillets in their edge regions where they border on adjacent bumps. At least locally, the component has tensile strength values of >900 MPa, preferably >1200 MPa. No statement is made about the dimensioning of the deformation structure and the size of the fillets.

This component is obviously also made of thin sheet metal and is not intended for bulletproof vehicles.

For bullet-proof vehicles, mostly flat, unstructured plates made of armored steel with a large sheet thickness are used as protective plates behind the body components, but they are very heavy. With such flat, unstructured panels, the elastic waves introduced into the material by the load are reflected on the back and run back in the sheet metal. This leads to increased constructive interference of the waves running back and forth, which results in excessive local material stress and ultimately in material failure (see Fig figure 1 According to the state of the art). In order to nevertheless prevent a bullet being shot through, the material thickness is typically selected (increased) in such a way that no failure occurs despite the locally occurring excessive loads due to interference.

The object of the invention is to design a protective plate made of sheet metal materials, in particular for special protection vehicles, in particular for armored cars, in such a way that there is little or no interference in the event of highly dynamic or sudden loads from gunfire, explosion (blast) or accident scenarios (crash). of the elastic waves occur and thus component failure can be prevented, whereby these structured protective plates should be able to be manufactured with a more homogeneous material structure and reproducible, low-distortion compared to unstructured plates and compared to flat, unstructured protective plates due to the increased ballistic holding power a lower weight have lower material thicknesses.

This object is solved by the characterizing features of the first claim.

Advantageous refinements result from the dependent claims.

The protective plate for special protection vehicles consists of bullet-resistant steel and, according to the invention, has a spatial structure which, in the event of an impact load, reflects waves introduced in the material of the protective plate at an angle deviating from 90° within the material of the protective plate.

From the introduced wave and the reflected wave, a resulting wave is created, which is greatly reduced.

This significantly reduces the penetrating power of the projectile.

The protective plate consists of bullet-resistant steel and has a spatial structure, the structure consisting of a regular arrangement of elevations extending in the X and Y directions on a front side of the protective plate and between them and adjacent depressions and where the Protective plate is formed in the area of their structuring over the entire sheet thickness.

The elevations are preferably formed like segments of a sphere and have a first radius. The indentations are preferably also formed like segments of a sphere and have a second radius.

The first radius is 6 to 20 times, in particular 10 to 20 times, the sheet thickness. The second radius is advantageously 2 to 8 times the value of the sheet metal thickness, in particular 3 to 8 times the value.

In an advantageous embodiment, the first radius has a value that is 3 to 5 times greater than the second radius.

The first radius and the second radius particularly preferably merge into one another tangentially.

The depth of the elevations preferably corresponds to 0.5 to 1.5 times the sheet metal thickness of the protective plate. Furthermore or alternatively, the depth of the indentations can also correspond to 0.5 to 1.5 times the sheet metal thickness of the protective plate.

Each elevation of the structure has a center point, with the centers of three adjacent elevations on a plane forming an equilateral triangle with an edge length and this triangle forming a smallest repeating structural building block.

Particularly preferably, each recess of the structure has a center, with the centers of three adjacent recesses on one plane also forming an equilateral triangle with a further edge length, this formed triangle forming a smallest repeating structural component.

The protective plate consists in particular of thick sheet metal and has a plate thickness or sheet metal thickness of 2 mm and more.

In order to ensure the bullet-resistant properties of the protective plate, it consists in particular of ballistic steel or heat-treated steel.

The protective plate is structured by hot forming in a cooled tool (press hardening) or by cold forming.

The invention ensures possible weight savings in the case of thick sheet metal protective plates produced by forming with a sheet metal thickness of more than 2.0 mm with a spatial structure for bombardment and explosion loads.

Experiments have shown that protective plates with the "spherical segment structure" produced by press hardening in particular have a significantly higher bullet resistance than flat protective plates made of the same material and with the same sheet thickness.

This enabled a sheet thickness reduction of approx. 1 to 3 mm (e.g. from 9.5 mm to 7.4 mm for the tested protection plates), which means that a considerable weight saving can be achieved.

The thick sheets used have a sheet thickness (plate thickness) of over 2.0 mm.

Sheets (thick sheets) made of bulletproof material in the form of ballistic steel, such as tempered steel, or steel with good ballistic properties, such as hard manganese steel, are preferably used.

Figur 1

Reflektion der durch ein Projektil erzeugten Wellen in einer ebenen unstrukturierten Schutzplatte nach dem Stand der Technik,

Figur 2

erfindungsgemäße Schutzplatte in der Draufsicht,

Figur 3

Schnitt A-A gemäß Figur 2,

Figur 4

Reflektion der durch ein Projektil erzeugten Wellen in einer strukturierten Schutzplatte nach der erfindungsgemäßen Lösung.

The invention is explained in more detail below using an exemplary embodiment and associated drawings. Show it:

figure 1

Reflection of the waves generated by a projectile in a prior art planar unstructured protective plate,

figure 2

protective plate according to the invention in plan view,

figure 3

Section AA according to figure 2 ,

figure 4

Reflection of the waves generated by a projectile in a structured protective plate according to the solution according to the invention.

figure 1 shows the cross section of a flat, unstructured protective plate 1 according to the prior art, in which the propagation of the waves when a projectile P strikes is shown as a schematic representation.

When the projectile P hits, the elastic waves W1 introduced into the material by the load are reflected at the back and travel back as reflected waves W2 in the metal sheet. This leads to increased constructive interference of the waves W1, W2 running back and forth, which result in excessive local material stress and ultimately in material failure, which is represented by wave W3 as the resultant wave with constructive interference. In order to nevertheless prevent a bullet being shot through, the material thickness b is typically selected (increased) in such a way that no failure occurs despite the locally occurring excessive loads due to interference.

In figure 2 the solution according to the invention is shown in plan view as a schematic diagram.

The protective plate 1 has a spatial structure 2 made up of a regular arrangement of elevations 3 . Between these elevations 3 adjoining depressions 4 are arranged, with the protective plate being deformed over the entire sheet thickness in the area of its structuring.

The center points M of the elevations 3 form an equilateral triangle with an edge length a on one level, which represents the smallest repeating structural component. On another level, the centers M1 of the depressions 4 form an equilateral triangle with an edge length a1, which represents the smallest repeating structural component.

The elevations 3 preferably have a radius R1 of about 20 mm to 250 mm and are rounded from the direction of a first side 5 of the protective plate 1 with a radius R1 and on the second side 6 facing away therefrom with a smaller radius R2. The Radius R1 merges tangentially into radius R2 and radius R2 merges tangentially into radius R1. The first side 5 is preferably the outward-facing side of the protective plate 1, the second side 6 is the inward-facing side in the direction of the vehicle interior. The increases 3 have the largest radius, the radius R1 to the outside. The indentations 4, which are formed by the radius R2, form smaller elevations on the second side 6.

The arrangement is such that the depth t of the elevations corresponds to 0.5 to 1.5 times the panel thickness b1. According to figure 3 the depth corresponds approximately to the plate thickness b1 of protective plate 1.

This geometry can be created by hot forging in a chilled tool or by cold forging. In any case, production always takes place with an upper and lower tool with a defined active surface.

Significantly smaller material thicknesses are possible with these thick sheet protective plates produced by forming with a three-dimensional structure when used as bulletproof protective plates for bullet and explosion loads, which has been confirmed by numerous ballistic tests.

The advantage of this arrangement of the elevations 3 is also a comparatively very small thinning of the material of the protective plate 1, with thinning values of less than 10% typically being able to be achieved.

In figure 4 shows a reflection of the waves generated by a projectile in a structured protective plate 1 according to the solution according to the invention. From this it can be seen that a resulting wave W3 arises from the introduced wave W1 and the reflected wave W2, which is greatly reduced.

The curved spherical segment-like geometry thus causes the elastic waves in the material to be reflected at an angle that deviates from 90°, which means that there can be little or no interference.

Accordingly, if the interference of the two waves can be prevented or reduced, it is possible to use significantly small plate thicknesses P1 for the protective plate 1 according to the invention, which withstand the load without interference.

The plate thickness b1 of the protective plate 1 according to the invention with structuring 2 can therefore be significantly reduced in comparison to a plate thickness b in the prior art.

In addition, the structuring 2 offers locally increased resistance moments against bending, which has a positive effect on the component rigidity. This locally increased rigidity also makes an important contribution to the improved performance of the structured panels under various impact loads.

With the solution according to the invention, smaller wall thicknesses can be used for certain load cases, which leads to a significant reduction in weight. Example: for 7.62x51 FMJ/PB/HC, P80 CBC at 820 m/s from a distance of 10 m on the material Inkas 7.3 (ballistic steel for press hardening - in-house development IndiKar with tensile strength of 2100 MPa) reduction from 9.2 mm to 8.0 mm sheet thickness 13%.

The protective plates are arranged in a known manner under an essentially conventional vehicle outer skin in the direction of the vehicle interior and thus offer the people in the vehicle reliable protection against fire up to fire class 10 according to VPAM PM 2007, Version 2.

The protective plates are used, for example, in special protection vehicles such as armored cars, military vehicles and personal protection equipment.

Reference List

1

protective plate

2

structuring

3

increase

4

deepening

5

first page

6

second page

a

edge length

a1

edge length

b

State-of-the-art plate thickness

b1

plate thickness

t

drawing depth

M

center elevation

M1

center deepening

P

projectile

R

Radius of a segment of a sphere

R1

first radius

R2

second radius

T

equilateral triangle

T1

equilateral triangle

w1

initiated waves

W2

reflected waves

W3

resulting waves

Claims (9)

1. Protective plate, in particular for special protective vehicles, wherein the protective plate (1) consists of bullet-resistant steel and has a spatial structuring (2), wherein the structuring (2) consists of a regular arrangement, extending in the X and Y directions, of elevations (3) on a front side of the protective plate (1) and of depressions (4) arranged between and adjoining these elevations (3), and wherein the protective plate (1) is formed over the entire sheet thickness (b1) in the region of its structuring (2),
   characterized in that
   the elevations (3) are designed in the manner of spherical segments and have a first radius (R1), and in that the depressions (4) are formed in the manner of spherical segments and have a second radius (R2), wherein the first radius (R1) and the second radius (R2) merge tangentially into one another and the outwardly facing elevations (3) form the larger radius (R1) and the depressions (4), which are formed by the radius (R2), are rounded with a smaller radius on the second side (6) facing the vehicle interior, and wherein the depth (t) of the elevations (3) and/or of the depressions correspond to 0.5 to 1.5 times the sheet thickness (b1) of the protective plate (1).
2. Protective plate according to claim 1, characterized in that the first radius (R1) is 6 to 20 times the sheet thickness (b1).
3. Protective plate according to claim 1, characterized in that the second radius (R2) is 2 to 8 times the sheet thickness (b1).
4. Protective plate according to claim 1, characterized in that the first radius (R1) is three to five times the second radius (R2).
5. Protective plate according to one of claims 1 to 4, characterized in that each elevation (3) of the structuring (2) has a center point (M), wherein the center points (M) of three adjacent elevations (3) form on a plane an equilateral triangle (T) with an edge length (a), wherein the triangle (T) forms a smallest repeating structural component.
6. Protective plate according to one of claims 1 to 5, characterized in that each depression (4) of the structuring (2) has a midpoint (M1), wherein the midpoints (M1) of three adjacent depressions (4) form on a plane an equilateral triangle (T1) with an edge length (a1), wherein the triangle (T1) forms a smallest repeating structural component.
7. Protective plate according to one of claims 1 to 6, characterized in that the protective plate (1) consists of a thick sheet and has a plate thickness (b1) from 2 mm and above.
8. Protective plate according to one of claims 1 to 7, characterized in that the protective plate (1) consists of ballistic steel or heat-treated steel.
9. Protective plate according to one of claims 1 to 8, characterized in that the structuring (2) is produced by hot forming in a cooled tool (press hardening) or by cold forming.

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