GB2158910A

GB2158910A - Fixing elements and driving tools

Info

Publication number: GB2158910A
Application number: GB08409204A
Authority: GB
Inventors: Robert Horrace Seba Montefiore; Ross Harrison
Original assignee: CLERKENWELL SCREWS Ltd
Current assignee: CLERKENWELL SCREWS Ltd
Priority date: 1984-04-10
Filing date: 1984-04-10
Publication date: 1985-11-20
Also published as: GB8409204D0

Abstract

Fixing elements having a shank and a head (3) are provided in which the head periphery so shaped as to be difficult to turn using conventional tools the head (3) (Fig. 1) viewed along the axis of the shank having a generally circular periphery provided with one or more flat, indented or protruding portions (4), the or each flat indented or protruding portion being diametrically opposed by a convex portion; alternatively, the head (3) (Fig. 5) is frusto-conical and formed with indentations (10). <IMAGE>

Description

SPECIFICATION Fixing elements and tools The present invention relates to fixing elements having a shank and a head and designed to be engaged and released by turning the head and to tools for turning the head of such fixing elements.

Conventional wood screws, machine screws, bolts and similar fixing elements have a shank and a head adapted to be turned by one of a variety of commonly available tools.

Because the tools by means of which such fixing elements can be removed are commonly available, these fixing elements provide no security against tampering or theft.

There is therefore a continuing need for fixing elements so designed that they can only be released or removed by the use of a special tool and cannot be removed by the use of conventional tools, or at least not without considerably difficulty.

There are a number of fixing elements of the nature of screws available having heads containing one or more bores so shaped as to engage protrusions on a tool, eg square or star shaped bores. Such fixing elements can often be removed by using an ordinary screw driver blade so sized as to jam in the shaped bore of the fixing element or by some other improvisation using conventional tools.

Furthermore, the appearance of these known fixing elements is often somewhat unattractive. It will be appreciated that fixing elements of this nature are often used to secure items of particular value and it is therefore undesirable that the overall appearance of the items of value be spoilt by unattractive fixings.

The present invention provides fixing elements of various designs and special tools adapted for their fixing and release, and in particular fixing elements having a head and a shank, with the head periphery being so shaped as to be difficult to turn using conventional tools.

In a first embodiment, the present invention provides a fixing element having a head and a shank bearing fixing means adapted to be engaged and released by turning, wherein the head viewed along the axis of the shank has a generally circular periphery having one or a few flat, indented or protruding portions, the or each flat indented or protruding portion being diametrically opposed by a convex portion.

The flat, indented or protruding portions enable a correspondingly shaped tool to grip the head. Preferably, these portions are flat or indented.

In a second embodiment according to the invention, there is provided a fixing element having a head and a shank bearing fixing means engaged and released by turning the head, wherein the head viewed along the axis of the shank has a periphery provided with a multitude of small indentations or protrusions and viewed from the side of the fixing element the edge of the head is inclined to the axis of the fixing element.

With reference to the first embodiment of the invention, the head preferably has a single flat. The flat preferably subtends an angle at the axis of the shank of from 30 to 90t, eg.

60".

The head may be provided with a pair of flats so situated that they are not opposite each other but are each opposed by a curved portion of the head.

In a particularly preferred aspect, the invention provides a fixing element having a head and a shank bearing fixing means adapted to be engaged and released by turning, wherein the head viewed along the axis of the shank has a generally circular periphery having two or more flats, none being parallel to another.

It is particularly preferred that there be two flats. Preferably the flats are separated by curved portions of the head periphery. Preferably, where there are two flats they are at an angle of 20 to 50 to one another, e.g.

about 35 .

In such an arrangement it is particularly preferred that the end of one flat is diametrically opposed to the centre of a second. This serves to steepen the convexity of the periphery of the head diametrically opposite the centre of said second flat, making it more difficult for a grip to be obtained by a pair of parallel jaws.

In an alternative arrangement according to the first embodiment of the invention, the head is provided with one or more indented portions in its periphery. Preferably, the head has a single indentation. Preferably, the or each indentation is a shallow, curved indentation.

In such an embodiment, the portion of the periphery of the head including each indentation may be serpentine in shape.

The head, viewed from the side, is preferably flat but may be of any other desired shape, eg. domed.

Fixing elements according to the second aspect of the invention are provided with a multitude of small indentations on protrusions in the periphery of the head of the fixing element. These may extend around the whole of the circumference of the fixing element head or may be restricted to certain parts of the circumference.

Preferably, viewed from the side of the fixing elements, the edge of the head is inclined to the axis of the fixing element by an angle of from 10 to 50 , e.g. 204 to 40 , most preferably 30 .

Each small indentation preferably subtends an angle of from 10 to 20 at the axis of the fixing element so that eighteen to thirty six such indentations may be arranged around the circumferance of the head.

The fixing element may a wood screw, machine screw or bolt, or a screw of any other kind. The fixing element may of any other nature designed for engagement and release by rotation.

The invention includes a fixing tool adapted for turning a fixing element of the first or the second aspect of the invention and comprising a handle member and a fixing element engaging head including a recess for receiving the head of the fixing element and having internal formations adapted to engage the head of the fixing element whereby the fixing may be rotated by the tool.

The invention also provides a fixing kit comprising a fixing tool as described and a plurality of fixing elements of corresponding type.

Preferably, the internal formations in the recess in the head of the tool are such as to substantially exactly match the shape of the head of the fixing element for which the tool is designed.

The present invention will be illustrated by the following description of preferred embodiments of fixing elements and tools according to the invention with reference to the accompanying drawings in which: Figure 1 is a view along the axis of a fixing element according to the first aspect of the invention, Figure 2 is a view from the side of the fixing element of Fig. 1, Figure 3 is a perspective view from one end of a tool for use with the fixing element of Figs. 1 and 2, Figure 4 is a view along the axis of a fixing element according to the second aspect of the invention, Figure 5 is a side view of the fixing element of Fig. 4, and Figure 6 is a perspective view of a tool for use with the fixing element of Figs. 4 and 5.

Figure 7 is a view along the axis of a second fixing element according to the first aspect of the invention.

Figure 8 is a view along the axis of a third fixing element according to the invention.

As shown in Figs. 1 and 2, a fixing element 1 comprises a shank 2 and a head 3. As seen in plan view of Fig. 1, the head is circular in shape except for a flat 4 subtending an angle of approximately 60 at the centre of the head. The shank 2 is formed as a conventional wood screw shank but would equally well be any other kind of screw shank.

As shown in Fig. 3, a tool for screwing in and removing the fixing element shown in Figs. 1 and 2 comprises a handle 5 of a conventional nature bearing a shaft 6 extending co-axially therefrom. A head 7 mounted on one end of the shaft 6 has a cup-shaped recess 8 which is generally of circular crosssection matching the diameter of the head 3 of the fixing element but has a flat 9 obstructing the circular bore of the recess 8. The flat 9 is matches the flat 4 and provides engagement for rotation when the tool is applied to the head of the fixing element 1.

As shown in Figs. 4 and 5, an embodiment according to the second aspect of the invention is provided by a fixing element 1 having a shank 2, only the part of which adjacent the head is shown, the remainder being of a conventional type for a wood screw. The fixing element has a head 3 provided with a multitude of small indentations 10 so that the head is effectively coarsely knurled. Viewed from the side as seen in Fig. 5, the sides of the head are angled with respect to the shaft at an angle of approximately 30 , making it more difficult to obtain a grip on the head by means of tools such as pliers.

The tool shown in Fig. 6 for use with the fixing element of Figs. 4 and 5 is generally similar to that shown in Fig. 3 except that the recess 8 in the head 7 is provided with formations complimentary to the numerous indentations 10 on the fixing element. The numerous protrusions 11 in the recess are adapted to lock with the indentations 10. It will be appreciated that since the indentations 10 are so closely spaced, the formations on the head of the fixing element can in the alternative be considered as numerous protrusions from the head and the formations in the tool can be viewed as numerous indentations.

As shown in Fig. 7, the head of a second fixing element according to the first aspect of the invention has an indentation 4a. The portion of the periphery of the head involved in the indentation is serpentine in shape, such that the indentation is steeper at the more clockwise end of the indentation.

As shown in Fig. 8, the head of a further fixing element according to the invention has a pair of flats 4 disposed at an angle of 35' to one another, and such that the centre of one flat is diametrically opposite an end of the other. The length of each flat is suitably about 10 to 30% of the circumference of the head.

Thus a fixing element having a maximum head diameter of 11 mm might suitably have two 5 mm flats.

The portion of the periphery opposite each flat is rendered more steeply convex by including the junction between circular and flat positions, thus making it more difficult to get a grip using a pinching type of tool.

Each of the fixing elements illustrated has the advantage of providing an attractive and unobtrusive appearance since the head is formed without recesses or bores of any kind.

Each of these is adapted to be engaged by a special tool provided for the purpose and to be difficult to engage using common tools such as screw drivers of normal types or gripping tools such as pliers or pincers. Each can therefore advantageously be used for securing items of value against vandalism, tampering or theft whilst still allowing these items to be removed by the use of the proper tool which will not be commonly be available.

Many modifications and variations of the invention as described with reference to the specific embodiments are possible without departing from the scope of the invention.

Claims

1. A fixing element having a head and a shank bearing fixing means adapted to be engaged and released by turning, wherein the head viewed along the axis of the shank has a generally circular periphery having one or a few flat, indented or protruding portions, the or each flat indented or protruding portion being diametrically opposed by a convex portion.

2. A fixing element as claimed in Claim 1, wherein the head has a single flat.

3. A fixing element as claimed in Claim 2, wherein the flat subtends an angle at the axis of the shank of from 30 to 90 .

4. A fixing element as claimed in Claim 3, wherein the flat subtends an angle at the axis of the shank of about 60 .

5. A fixing element as claimed in Claim 1, wherein the head is provided with a pair of flats so situated that they are not opposite each other but are each opposed by a curved portion of the head.

6. A fixing element having a head and a shank bearing fixing means adapted to be engaged and released by turning, wherein the head viewed along the axis of the shank has a generally circular periphery having two or more flats, none being parallel to another.

7. A fixing element as claimed in Claim 6, wherein the head has two flats at an angle of 20 to 50 to one another.

8. A fixing element as claimed in Claim 7, wherein the two flats are at an angle of about 35 to one another.

9. A fixing element as claimed in any one of Claims 6 to 8, wherein the end of one flat is diametrically opposed to the centre of a second.

10. A fixing element as claimed in Claim 1, wherein the head is provided with a single said indented portion.

11. A fixing element as claimed in Claim 1 or Claim 10, wherein the or each indentation is a shallow, curved indentation.

1 2. A fixing element as claimed in Claim 11, wherein the portion of the periphery of the head including the or each indented portion is serpentine in shape.

1 3. A fixing element having a head and a shank bearing fixing means engaged and released by turning the head, wherein the head viewed along the axis of the shank has a periphery provided with a multitude of small indentations or protrusions and viewed from the side of the fixing element the edge of the head is inclined to the axis of the fixing element.

14. A fixing element as claimed in Claim 13, wherein viewed from the side of the fixing element, the edge of the head is inclined to the axis of the fixing element by an angle of from 10 to 50 .

1 5. A fixing element as claimed in Claim 14, wherein said angle is 20 to 40 .

16. A fixing element as claimed in any one of Claims 1 3 to 15, wherein each small indentation subtends an angle of from 10 to 20 at the axis of the fixing element.

1 7. A fixing element substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, 4 and 5, 7 or 8 of the accompanying drawings.

1 8. A fixing tool adapted for turning a fixing element as claimed in any preceding claim and comprising a handle member and a fixing element engaging head including a recess for receiving the head of the fixing element and having internal formations adapted to engage the head of the fixing element whereby the fixing may be rotated by the tool.

1 9. A fixing tool substantially as hereinbefore described with reference to and as illustrated in Figs. 3 or 6 of the accompanying drawings.

20. A fixing kit comprising a fixing tool as claimed in Claim 18, and a plurality of fixing elements of corresponding type.