A Self Drilling Anti-Removal Screw and Tool

Field of the Invention.

This invention is directed to a self drilling fastener (typically a self drilling or self tapping screw), and which has a particular head configuration which prevents unauthorised removal of the screw. The invention is also directed to a specially designed tool that can be used by an authorised person to remove the screw if this is required. While the invention will be described with reference to a self drilling fastener, it is envisaged that the particular head configuration and the tool may also be used on other types of fasteners such as bolts and the like which may not be self drilling. The invention may also be directed to a particular method by which the screw or fastener can be removed.

Background Art.

There are many circumstances where it is desirable to have fasteners which cannot be tampered with by being removed. As an example, outdoor sheds are often assembled using self drilling screws or nuts and bolts. If the screws could be removed, it would be easy to enter the shed simply by removing the screws, and removing a wall panel.

Sometimes, this difficulty does not present itself as the panels can be attached using welding or nails, but there are many circumstances (particularly with all metal construction but using thin wall metal members) where welding and nailing cannot be done and self tapping screws or nuts and bolts are required.

There are many types of fasteners (particularly screws and bolts) which have a special design to allow the screws to be rotated in one direction (the fastening direction) but not the other direction (the un-fastening direction). These fasteners are often called

"one-way" fasteners or "tamper evident" fasteners, or "security" fasteners and the like. However, these fasteners have a number of disadvantages.

One type of security fastener comprises a screw or a bolt containing a head. The head contains a socket, and the socket has a particular internal profile to enable a tool to rotate the fastener in one way but not the other way. One disadvantage with this type of arrangement is that the head needs to be quite large to accommodate the socket. If the head is relatively small, the socket is either so small that it cannot function properly, or if the socket is made larger, the amount of remaining head portion is so small that the head can be quite easily destroyed upon over rotation (especially with electric drills and the like). Also, the socket can quite easily fill with debris and grime making rotation of the fastener difficult. Thus, security fasteners containing recesses or sockets in the head are generally not desirable.

An early type of security fastener used a head having a particular design and the tool was a flat blade screwdriver . These fasteners were quite difficult to fasten as the screwdriver blade would often slip during use and therefore this type of fastener is also generally not desirable.

Another type of security fastener again comprises a head portion but this time, instead of the head portion containing a socket, the head portion has a particular design to engage with a (often specially designed) tool in one direction (the tightening direction) but not the other direction. The present invention is generally directed to this type of security fastener but with improvements in the design of the head portion.

Existing security fasteners of this general type suffer from some disadvantages. One disadvantage is that the configuration of the head is often quite complicated which adds to the cost of the manufacture of the fastener. Sometimes , the head contains a complicated arrangement of projections and profiles (often more than four or six), and this makes each projection quite small and therefore susceptible to damage. Once such a projection is damaged, it is often the case that the tool can no longer tighten the fastener.

Another disadvantage with several types of security fasteners is that the fastener contains a threaded shank portion and a head portion with the head portion being about the same size as the shank portion. This makes it difficult to provide a properly

designed profile on the head to enable the fastener to be rotated in one direction but not the other direction, basically because the head is not large enough. Simply making a larger head without any other design considerations can result in the head snapping of the shank portion which is undesirable.

Another disadvantage with most fasteners is that the head is designed such that it can be rotated in the other direction providing that a special differently designed tool is used. Thus, the head needed to have a design that enabled it to be fastened using a conventional or available type tool, but also needed to have the design that would enable another tool (usually a tool with restricted circulation) to fit the head and to enable the head to be rotated in the other way. These complicated design requirements resulted in the fasteners being expensive to manufacture and having head portions that could be quite easily made useless with rough handling, slight damage and the like.

The present invention is directed to a "one-way" type fastener having a particular head design.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Object of the Invention.

It is an object of the invention to provide a one-way fastener which may overcome at least some of the above-mentioned disadvantages or provide a useful or commercial choice, or a method for attaching and removing a security fastener.

hi one form, the invention resides in a method for attaching and removing a one-way fastener from a member to which the fastener is attached, the method comprising providing a fastener having a shank portion which may be threaded, the shank portion comprising tool engagement means to allow the fastener to be loosened, the fastener further comprising a head portion, the head portion having a configuration that

enables a tool to rotate the head portion in one direction but prevents or restricts rotation of the head in the other direction, drilling the fastener through the member (for instance sheet steel), typically by attaching a tool to the head portion of the fastener and rotating the tool to rotate the head portion thereby drilling the fastener through the member, a portion of the shank of the fastener extending through the member, the tool engagement means able to attach to parts of the shank of the fastener and able to rotate the fastener in the opposite direction thereby un-screwing the fastener from the member.

hi this particular method, the head of the fastener may be designed such that it can be rotated in the tightening direction but cannot be rotated (via the head portion) in the other direction. Thus, it need not be necessary to design the head portion in such a manner that another type tool can engage the head portion to unscrew the fastener.

Instead, and in this particular method, the arrangement is that the length of the fastener is greater than the thickness of material such that the front of the shank projects through the material in the inside of the building ( for example). The projecting part has some profile or something that allows a tool to engage with the projecting part and rotation of the tool in the other direction causes the fastener to unscrew from the inside of the building.

In a particularly preferred form of the method, the fastener is a self drilling fastener and therefore contains some form of cutting head on the tip of the shank. The cutting head typically comprises a profile which is ideal for attachment to the " unscrewing" tool. Usually, the cutting head comprises a pair of opposed cutting edges and these present a purchase to allow a tool with a corresponding slot or recess to extend over or at least partially over the cutting head such that rotation of the tool in the other direction causes the fastener to become unscrewed. Thus, the fastener can be unscrewed from the "inside" but not from the "outside".

The tool to assist in loosening of the fastener may be known as the "unscrewing" or "screw removing tool" or the " loosening tool". This tool will typically be of the type that can be attached to a drill or other type of device, although there may be instances

where the tool is provided with a head portion to allow to be used manually.

The tool may comprise a "socket " type member having a rear end formed with a opening to accommodate a drive bit from a drill. Alternatively, the rear end may be provided with a "bit" to enable it to be fastened directly to the chuck of the drill. It is preferred that the loosening and the tightening tool have the same configuration for the drill.

The other end of the tool will typically comprise some form of opening or something else to engage with the tip of the screw to allow the screw to be removed. The screw can then be removed at least partially and it may then be possible to rotate the other end of the screw (that is the head) manually to remove the screw entirely from the member.

However, in another form, the "loosening" or screw removing tool, may contain a shank portion which approximates the diameter of the shank portion of the fastener such that when the tool engages with the fastener (typically the cutting tip, if a cutting tip is provided) the tool can rotate the fastener all the way out of the drilled hole, as the shank portion of the tool will be able to pass through the drilled hole.

How the tool is attached to the fastener can vary and will depend on the particular profile of the tip portion of the fastener. If the fastener is a self drilling or self tapping fastener having a cutting head, it is envisaged that the front of the shank portion of the tool will contain an opening or slot which can engage with the cutting tip in such a manner that rotation of the tool will cause rotation of the fastener.

In another form, the invention resides in a fastener which can be rotated in one direction using a particular tool but not in the other direction, the fastener comprising a shank portion typically containing threads and a cutting tip, a collar portion and a head portion ( which may be formed together), the collar portion being below the head portion and supporting part of the head portion, the head portion having a configuration to enable the tool to rotate the fastener in one direction but not the other direction.

In another more particular form, the invention resides in a fastener which can be rotated in one direction using a particular tool but not in the other direction, the fastener comprising a shank portion, a collar portion, and a head portion, the collar portion being positioned immediately below the head portion and providing support for part of the head portion, the head portion having a central raised portion and a pair of opposed shoulder portions, each shoulder portion extending from the central raised portion and towards a peripheral edge of the collar portion, each shoulder portion having a tool engaging face on one side of the shoulder portion and a tool sliding face on the other side of the shoulder portion the construction and arrangement of this being to enable a tool to engage with the engaging face on each shoulder portion to enable the fastener to be tightened, unable to engage with the head portion and/or shoulder portions when rotated in the other direction thereby preventing the fastener from being loosened.

The advantage of providing the collar portion is that this enables the head portion to be made much larger while still providing support for the head portion.

The fastener may comprise a screw fastener a bolt, or something else. It is preferred that the fastener comprises a screw fastener. The shank portion of the fastener may be of any convenient length and it is envisaged that the length will be between 10-200 mm although it is not envisaged that any particular limitation should be placed on the invention with these lengths. Similarly, the thickness of the shank portion may vary to suit and it is envisaged that a suitable thickness will be between 2-10 mm.

The fastener is usually made of metal such as steel although there may be situations where the fastener needs to be made of other materials.

The shank portion may be provided with threads either entirely along the shank portion or along parts of the shank portion.

The shank portion may terminate with a cutting tip to enable the fastener to be a self drilling or self tapping fastener. It is envisaged that conventional cutting tips may be

used. These conventional cutting tips may be sharpened or hardened ( for instance by being coated with hard facing material and the like).

The fastener may contain a collar portion which may comprise a disk or something similar. The collar portion is typically rigidly attached to the shank and this can be carried out by a spot weld or by some form of integral machining or other means. The collar portion will typically be provided adjacent the other end of the shank portion and typically immediately below the head. The size of the collar portion may vary but it is considered that the collar portion will have a diameter or cross-section of between 5-30 mm and typically between 10-20 mm. The collar portion will typically be circular but there may be circumstances where the collar portion may be rectangular, oval, triangular or have other shapes. The thickness of the collar portion may vary but it is envisaged that the collar portion will have a thickness of between 0.5-2 mm if the collar portion is made of metal.

The collar portion may be formed integrally with the head portion in which case the collar portion may comprise a bottom face of the head portion.

One function of the collar portion is to provide a larger "platform" for the particularly profiled head portion.

The head portion has a particular configuration to enable "one-way" fastening to occur. In one form, the head portion comprises a substantially integrated construction which means that the head portion does not comprise separated portions (which may suffer from weakness and easy damage). Thus, it is preferred that the head portion has a central raised portion which is solid and a pair of opposed shoulder portions which are also solid. These shoulder portions may extend oppositely from each other.

One function of the collar portion is to provide support for these shoulder portions which may otherwise be quite easily damaged if not supported. Another function of the collar portion is to provide a relatively large platform such that the shoulder portions can be made larger than may otherwise be possible (and therefore less susceptible to damage).

There may be circumstances where more than a pair of shoulder portions may be provided such as three shoulder portions or four shoulder portions. However, it seems that a pair of shoulder portions provides a quite functional product and therefore it is not considered that more than a pair of shoulder portions would usually be required.

Each shoulder portion will typically have a tool engaging face and it is considered convenient that the tool engaging face is on one side or edge of the shoulder portion. The tool engaging face may comprise a face which is substantially at 90° from the plane of the collar portion.

Brief Description of the Drawings.

An embodiment of the invention will be described with reference to the following drawings in which:.

Figure 1. Illustrates a fastener according to an embodiment of the invention.

Figure 2. Illustrates the same fastener from a different angle. Figure 3. Illustrates the head portion of the fastener on top of the collar portion.

Figure 4. Illustrates the head portion from a different angle.

Figure 5. Illustrates the head portion from a different angle again.

Figure 6. Illustrates a tool that can be used to tighten the fastener.

Figure 7. Illustrates a top view of the tool of figure 6. Figure 8. Illustrates the screw removal tool.

Best Mode.

Referring to the illustrations and initially to figures 1-4, there is illustrated a self drilling screw 10 comprising a shank 11 having a lower threaded portion 12 and a cutting tip 13. The other end of screw 10 contains a specially designed head portion 14 and a collar portion 15.

Referring to figures 3-4, collar portion 15 provides a support platform for the specially designed head portion 14 ( collar portion and head portion being formed together). Head portion 14 has a central raised portion 17 which is solid, and a pair of opposed shoulder portions 18, 19 which extend from head portion 18 and towards (but somewhat inwardly from) the periphery of collar portion 15.

Each shoulder portion is somewhat wedge shaped having a narrower portion adjacent central portion 17 and a broader portion adjacent the periphery of collar portion 15. This arrangement can provide strength to the entire head portion to enable a driving tool (see for instance figure 6-7) to properly drive the fastener through a material (such as sheetmetal). Each shoulder portion 18, 19 contains an abrupt face 20, 21 on one side which functions as a "tool engaging face" to engage with the driving tool which will be described in greater detail below.

The other side of each shoulder portion does not have an abrupt face and instead is deliberately rounded 22, 23 which means that there is no "grip" or "purchase" on the head if counter rotation of the screw is attempted from the head end of the screw.

Figures 6-7 illustrates the "working end" of a driving tool 24. Driving tool 24 contains an end face formed with a recess 25. Recess 25 contains a pair of abrupt faces 26, 27 which are adapted to engage with the similar abrupt faces on the head portion of the screw to allow the screw to be rotated in the "tightening" direction.

The other side of each abrupt face 26, 27 in the driving tool (these faces being identified with reference numerals 28, 29 are not abrupt, but instead are deliberately angled or rounded or made shallow such that this area can not readily engage with any part of the head of the screw.

The driving tool can be fitted to a cordless drill or something else and placed over the top of the screw to readily drill the screws through sheetmetal or other members.

It is preferred that the screw has a length which is greater than the thickness of the

metal such that the tip portion 13 of the screw projects from the "inside" of the material. This allows the screw to be removed if required.

To do so, a second tool (figure 8) is provided. This tool 31 (the screw removing tool) comprises a cylindrical member formed with an opening 30 in the front face which is adapted to grip the cutting tip 13 of screw 10 and in such a manner that the screw cannot rotate relative to this tool. This tool can also contain a bit 32 to enable it to be fitted to a chuck of a drill. Rotation of this tool in the opposite direction will cause the screw to be screwed out of the material until the front of the tool 31 hits the material. By this time, the screw will have been removed by a few millimetres and sufficiently loosened to allow a person to grip the other end of the screw (the head end) and continue to rotate and remove the screw from the material.

The usual rubber/plastic seal may be provided below the collar portion.

Throughout the specification and the claims (if present), unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.