GB2143309A - Fixing means for armoured panels - Google Patents

Abstract

An armoured, eg. bullet-resistant, panel 1 is secured in to struts 2, 3 a vehicle door by means of four fixing members 5-8. The fixing members each have a steel bolt 12 with an enlarged head 22 having a recess 23 which receives a disc 25 of a hard, penetration-resistant, brittle material eg. a ceramic material. The edge of the head 22 is rolled over the disc 25 to retain it in position. The floor of the recess 23 has a groove 24 around its periphery, and a layer 27 of resilient material under the disc. A hard rubber washer 30 is positioned between the head 22 and the panel 1. The shank 20 of the bolt 12 passes through the panel 1 and is screw threaded to receive a nut 10. Alternatively (Figure 5), the disc 25 is secured entirely by means of an adhesive (50). <IMAGE>

Description

SPECIFICATION Fixing members This invention relates to fixing members.

The invention is more particularly concerned with impact resisting fixing members for use in supporting armoured panels, such as in vehicles.

Armoured panels, such as of steel or ceramic composites, are secured in position by means of one or more bolts that extend through holes in the panel.

The bolts potentially provide a weak spot in the armour and are preferably designed to withstand the same impact threat as the armoured panel itself. The bolt also should be designed such that when its head is hit by a bullet or similar missile, the shank of the bolt does not shear from the head to produce a secondary projectile.

One form of conventional bolt is made from a single piece of steel, the head being of conical shape so that, on impact, the bullet is deflected away from the bolt. Whilst such bolts can provide a secure mounting they can increase the risk of damage caused by ricochet. Because the head of such bolts must project a significant distance from the armoured panel it can make installation difficult in confined spaces. Another way of supporting armoured panels is to locate the head of the bolt on the side of the panel opposite the impact and to use at least two nuts on the side of the panel facing the impact. This, however, also leads to an increase in the overall thickness of the armour.

It is an object of the present invention to provide a fixing member that can be used substantially to alleviate the disadvantages of previous fixing members.

According to one aspect of the present invention there is provided a fixing member having a bolt member with a shank portion and an enlarged head portion at one end, said fixing member including a member of a hard, penetration-resistant, brittle material secured with the head portion of said bolt member.

Impact with the head of the fixing member, such as by a bullet, causes the energy of the bullet to be dissipated in fracturing the brittle material. In this way the risk of ricochet is substantially reduced.

When hit by an armour piercing round, the brittle material breaks up the armour piercing core of the round. The head of the fixing member can be slim, thereby facilitating installation.

The brittle material may be a ceramic material and may be of disc shape. The bolt member may be of steel and its head portion may have a recess within which said member of a brittle material is received.

The floor of the recess may have a groove around its periphery. The member of brittle material may be secured with said head portion by folding over a part of said head portion to overlap the member or brittle material. The circumference of the head portion may be flared. A layer of resilient material may be included between the head portion and the member of brittle material. The other end of the shank portion may be formed with a screw-thread which may be externally around the shank portion or internally in the shank portion. The fixing member may include a washer of energy absorbing material which encompasses the shaft, adjacent the head.

According to another aspect of the present invention there is provided a protective assembly comprising a penetration-resistant panel having one or more mounting apertures therein, and one or more fixing members according to the said one aspect of the present invention that are arranged to extend through the one or more mounting apertures to mount the panel.

The panel may include a layer of ceramic material.

A fixing member and a protective assembly including such a fixing member, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a protective assembly as installed in the door of a vehicle; Figure 2 is a sectional view of the fixing member; Figure 3 is a plan view of the fixing member of Figure 2; Figures 4 and 5 illustrate two alternative fixing members.

With reference to Figure 1 there is shown a bullet-resistant panel 1 that is secured to two upright struts 2 and 3 in a vehicle door 4 (only the inner part of which is shown) by means of four fixing members 5 to 8. The panel 1 is of conventional construction and may, for example, have a ceramic layer backed with layers of aramic fibre, or have a metal layer such as of steel or aluminium. The front surface 9 of the panel 1 faces outwardly of the vehicle, that is, towards the threat. Each fixing member 5 5O 8 includes a bolt that pasesthrough respective holes in the panel 1 and the struts 2 and 3. The front end of each bolt has a bullet-resistant head (to be described in detail later) that protects the bolt, whilst the rear end projects from the rear of the struts 2 and 3 and is secured by a nut 10.

With reference now to Figures 2 and 3, each fixing member has a bolt 12 formed from a single piece of steel and comprises a cylindrical shank 20 about 41 mm long and 12mm in diameterthat projects through a hole 100 in the panel 1. The rear end 21 of the shank 20 is screw threaded to receive the nut 10.

At the forward end of the bolt 12 is a circular head 22 about 39mm in diameter. The outside of the head 22 is tapered forwardly to a smaller diameter and may be provided with flutes (not shown) around its edge to enable the head to be gripped by a spanner. The tapered head provides it with greater strength.

Centrally of the head 22 there is a circular recess 23 about 32mm in diameter, the floor of which is formed with a shallow groove 24 around the periphery. Within the recess 23 is located a circular disc 25 of a brittle, penetration-resistant material, such as, an alumina ceramic, for example, Sintox (Registered Trade Mark of Smiths Industries Public Limited Company). The disc 25 is about 6mm thick, the front edge 26 being chamfered. A thin layer 27 of a resilient material, such as silicone rubber, is placed between the floor of the recess 23 and the disc 25, the groove 24 ensures that contact of the disc with the floor of the recess is not localised at the edge.

The front edge 28 of the head 22 is rolled inwardly to overlap the chamfered edge 26 of the disc 25 and to retain it securely in the recess 23. The layer 27 allows some displacement of the disc 25, during the rolling operating so as to reduce the risk of damage to the disc.

Between the front face 9 of the panel 1 and the rear of the head 22 there is positioned a washer 30 that is the same diameter as the head 22 and is about 4mm thick. The washer 30 is of a high energy absorbing material having a Shore hardness between 40-80 degrees and, in this respect a polyurethane rubber having a 60 degree Shore hardness may be used. A steel washer 31 is interposed between the nut 10 and the back of the strut 2, 3 to which the panel 1 is secured.

The fixing member is thightened about the panel 1 and the strut 2,3 by means of a torque wrench, to a maximum torque of about 1 Oftt1 b. The nut 10 is then secured in position by means of a screw-thread sealing compound.

When the front surface of the fixing member 5 to 8 is hit by a projectile, such as a bullet, the energy of the bullet is dissipated by fracturing the ceramic disc 25, the bullet then has only little residual energy for penetrating the fixing member. Any ricochet will also have very low energy. The ceramic disc 25 can also be effective in breaking up the steel core of armour piercing rounds.

Various alternative fixing members are also possible. For example, with reference to Figure 4, the shank 201 of the fixing member bolt may have an internal screw thread 202 that is engaged by an externally threaded screw 203. This enables the shank to be made shorter than is possible with the arrangement shown in Figure 2 since the rear of the shank does not have to project from the rear face of the panel. This can have advantages in making installation of the panel easier.

The ceramic disc 25 need not be secured in the same way as described with reference to Figure 2.

Instead of bending over the entire front edge 28 of the head 22 to retain the disc, the head could be provided with separate fingers that are folded over the disc. The head 22 could also be heat shrunk about the disc such that the disc is held in compression. This can give the ceramic greater strength but requires accurate machining to ensure a close fit within the head and to prevent undue stress. Alternatively, as shown in Figure 5, the disc 25 could be secured entirely by means of an adhesive 50.

It will be appreciated that the invention is not restricted to fixing members for bullet-resistant panels but can be used for other panels resistant to impact from other bodies or particles.

Claims (20)

1. Afixing member having a bolt member with a shank portion and an enlarged head portion at one end, wherein said fixing member includes a member of a hard, penetration-resistant, brittle material secured with the head portion of said bolt member.

2. Afixing member according to Claim 1,wherein said brittle material is a ceramic material.

3. Afixing member according to Claim 1 or 2, wherein said member of brittle material is of disc shape.

4. A fixing member according to any one of the preceding claims, wherein the bolt member is of a steel.

5. A fixing member according to any one of the preceding claims, wherein said head portion has a recess within which said member of brittle material is received.

6. A fixing member according to Claim 5, wherein the floor of said recess has a groove around its periphery.

7. Afixing member according to any one of the preceding claims, wherein said member of brittle material is secured with said head portion by folding a part of said head portion to overlap the member of brittle material.

8. Afixing member according to any one of the preceding claims, wherein the circumference of the head portion is flared.

9. A fixing member according to any one of the preceding claims including a layer of resilient material between the head portion and the member of brittle material.

10. Afixing member according to any one of the preceding claims, wherein the other end of said shank portion is formed with a screw thread.

11. A fixing member according to Claim 10, wherein the screw thread is formed externally around the shank portion.

12. Afixing member according to Claim 10, wherein the screw thread is formed internally in the other end of the shank portion.

13. Afixing member according to any one ofthe preceding claims including a washer of energy absorbing material which encompasses said shaft, adjacent the head.

14. Afixing member substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

15. Afixing membersubstantially as hereinbefore described with reference to Figures 1 and 4 of the accompanying drawings.

16. Afixing membersubstantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.

17. A protective assembly comprising a penetration-resistant panel having one or more mounting apertures therein, and one or more fixing members according to any one of the preceding claims that is or are arranged to extend through said one or more mounting apertures to mount said panel.

18. A protective assembly according to Claim 17, wherein said panel includes a layer of ceramic material.

19. A protective assembly substantially as hereinbefore described with reference to Figure 1 and Figures 2 and 3, or Figures 4 or 5.

20. Any novel feature or combination of features as hereinbefore described.