GB2280209A - Security bars - Google Patents

Abstract

Security bars (6) are mounted within tubes (2) on glass ball bearings (7) arranged so that an attack by hacksaw blades will cause a rotary spiralling motion of the bars. <IMAGE>

Description

SECURITY UNSAWABLE BARS This invention relates to unsawable security bars.

Security grills are more commonly known as security window bars usually comprising of mild steel rod welded to a frame to prevent entrance through doors or windows.

Security bars are relatively easy to gain entrance by sawing through and bending away, and provide more of a deterant than a prevention of access.

According to the present invention there is provided a concept of a hollow tube with a rod within mounted on glass balls which when attempts are made to saw through; the internal bar rotates together with lifting up and down in a spiral action thus preventing hacksaws engaging in a sawing effect.

A specific embodyment of the invention will be described by waxy of example with reference to the accompanying drawings in which: Figure 1 shows in section the device at rest Figure 2 shows in section the movement actioned by sawing.

Refering to the drawing the unsawable bars comprises of a central rod 3 within a tube 2 mounted over glass balls 7 supported therein by box section frame 1, 8 and 5 pre-drilled to accommodate the tube.

In order to prevent attack to the inner rod 3 by means of a hacksaw blade sufficient tolerance should be made for the rod to rotate within the tube when the outer tube 2 is sawn through.

In order to prevent diagonal attack by saw blade by means of jamming the rotation action glass balls 7 at the bottom of the rod within the tube together with a splayed angle 6 to the bottom of the rod cause a spiral up and down motion, together with the rotation motion, thus preventing engagement by blade.

To maintain flexibility of the rotation of the inner bar 3 the outer tube 2 must be supported to prevent flexing and this is done by means of intermediate channels 5.

The space 10 within the inner tube above the inner rod 3 must be of such a size to allow the spiral movement actioned by the glass balls at the bottom of the rod 6.

The glass balls 7 at the bottom inside of the tube must be such a size in ratio to the internal dimension of the tube to provide the rotation action compatible with the splay of the internal rod e.g. internal tube size l9mm, glass balls are llmm in diameter.

In addition to the glass balls 7, it is essential that the splay 6 on the bottom of the rod is of such an angle to produce the rotation action against the glass balls 260.

Claims (6)

1) Accoding to the present invention there is provided a concept of hollow tube with a rod within mounted on glass balls which when attempts are made to saw through the internal bar rotates together with lifting up and down in a spiral action thus preventing hacksaws to engage in a sawing effect.

2) Security insawable bars as in Claim 1 where in glass balls are provided to give spiral rotation to the rods must be of ratio in size to that of the hollow tube.

3) Security unsawable bars as claimed in Claim 1 or Claim 2, wherein the inner bar is splayed at bottom 260 to give spiral rotation action together with the glass balls.

4) Security unsawable bars as claims, wherein space is provided at the top of the outer tube for the inner rod to enable spiral action to operate.

5) Security unsawable bars as claimed in any preceeding claim, wherein the space between the inner bar and internal diameter of the outer tube is sufficient to allow rotation.

6) Security unsawable bars substantially as described herein with reference to figures 1-2.