AU2006207873B2

AU2006207873B2 - Metal cutting screw

Info

Publication number: AU2006207873B2
Application number: AU2006207873A
Authority: AU
Inventors: To Ha Loi
Original assignee: Loi & Tran Pty Ltd
Current assignee: Loi & Tran Pty Ltd
Priority date: 2005-09-07
Filing date: 2006-09-07
Publication date: 2011-06-16
Anticipated expiration: 2026-09-07
Also published as: AU2006207873A1

Description

Regulation 3.2 -1 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT APPLICANT: Loi & Tran Pty. Limited Invention Title: METAL CUTTING SCREW The following statement is a full description of this invention, including the best method of performing it known to me/us: -2 METAL CUTTING SCREW Technical Area This invention relates to a cutting screw and, in particular, to a screw which is adapted to connect panels to battens, studs, or the like, and specifically to connection of roof panels to battens. The invention will be described in relation to such screws without limiting the generality of the use of the screw. Background to the Invention There have previously been proposed screws, such as that illustrated in our previous Patent Co-operation Treaty application PCT/AU2001/01485 and in British Specification 2159745 of SFS Stadlerag screws which are specifically adapted for use with plastics or fibreglass sheeting and which include means whereby the hole formed through the sheeting by the screw is enlarged, either by cutting, as in our previous specification, or by abrasion, as in the British specification, so that the hole in the sheeting is of a larger diameter than the diameter of the screw. The reason for this is that where the panel, or for that matter, the batten to which the panel is connected, if this is of steel, is heated or cooled, there is a change in the dimensions of this and if the hole through the panel is effectively the same diameter as the screw, then there can be cracking Y:\SPECXLoj & Tran Metal Cutting Screw CAP 040906.wpd AT/CM 4/9/06 -3 and breakage of the panel. Such screws, whilst satisfactory in their application, have not been able to be used with steel or other metal panels. It is an object of the present invention to provide a screw which can be used to 5 connect metal panels to other members and which form, in the metal panel, a hole of a diameter larger than the diameter of the screw body, Outline of the Invention The invention provides a screw having an elongated cylindrical body, a cutting tip formed on one end of said body, a head on the other end of said body 10 whereby said screw is able to be rotated, and threads formed over a substantial part of the length of said body from adjacent said cutting tip, said threads being adapted to advance said screw into a sheet of material when said screw is rotated in a predetermined direction of rotation, characterised in that on said body between said threads and said head there is located a pair of wings which 15 extend from said body, and in thatthe radially outwardly-extending edge of each of said pair of wings has an inturned portion forming a cutting edge, said cutting edge extending towards said predetermined direction of rotation, Y:\Alfred\John C\LoI & Tran Metal Cutting Screw Amended Spec 11-05-04.wpd AT/CM 4/511 -4 The wings are preferably formed integrally from the body of the screw, although they could be attached thereto. Also, the tip of the screw could be designed specifically for use with wooden battens or the like, steel battens or may be a hybrid tip which can be used in either application. In use, there is normally a cupped washer or the like fitted above the wings and below the head to make a sealing contact with the aperture formed in the metal sheet. Description of an Embodiment of the Invention In order that the invention may be more readily understood, we shall describe one particular form of screw made in accordance with the invention in relation to the accompanying drawings, in which: Fig 1 is a perspective view of the screw from above; Fig 2 is an enlarged view of the wing of the screw; Fig 3 is a section through the screw just above the upper surface of the wing; Fig 4 is a view of the screw at the wing is about to effect enlargement of a sheet; and Fig 5 is a view similar to Fig 4 which the screw fully engaged. In general terms, the screw can be considered to be made in a conventional Y:\SPEC\Loi & Tran Metal Cutting Screw CAP 040906.wpd AT/CM 49/08 -5 manner, that is, by formation from a rod-stock which is rolled to have a thread 51 formed thereon, which can have a tip 53 manufactured by various processes to either be tapered, with the thread extending to the end thereof, or having a drill tip, as illustrated, which has cut-out portion and a head 52 at the end away from the drill tip. The head 52 is adapted to receive driving means and would normally be hexagonal adapted to be driven by a socket, spanner or the like, although it could, if necessary, be driven by Phillips-type indentations therein or in any other way is formed on the other end of the screw. Such screws are quite conventional and have been used in the industry for many years. In the screw of the invention, above the thread, we form a pair of effectively triangular wings 54. These can be formed by deformation out of the material of the screw. The wings are formed so that the apex of the triangle is downwardly-directed and they are diametrically opposite on the body. The hypotenuse 55 of each triangle is deformed slightly at 56 in the direction of rotation of the screw so there is, at the edge, an outwardly-directed relatively sharp tip, directed towards the direction of rotation of the screw. This tip, as illustrated, is small compared to the size of the triangle. YASPEC\Loi & Tran Metal Cutting Screw CAP 040906.wpd AT/CM 4/9/06 -6 Fitted over the screw and beneath the head of the screw, there can be a cupped washer 60 or the like, which extends downwardly and outwardly from the underside of the head of the screw. The screw of the invention is particularly useful with metal sheets, but it can also readily be used with polycarbonate or fibreglass sheets. The use of the screw of the invention is very similar to that of the conventional screws which provide an enlarged hole through the sheet 70 being fastened and that is, that the cutting tip, which would normally be a drill-point where the sheets are metal, is initially brought into contact with the sheet and on downward pressure, drills a hole therethrough. Further downward pressure will tend to cause the drill to move through the sheet and this would normally be facilitated by the thread 51 on the drill tending to pull the screw down, although if the sheet is thin, it may well be that the screw can simply be passed therethrough, until the drill-tip 53 reaches the batten to which the sheet is to be connected and, if this is a hollow metal batten, it will drill through the batten and again the screw will start to pull into the batten or, alternatively, if it is a wooden batten, the screw-point will simply pass into the batten and again, a thread will be formed on the aperture provided in the batten. This continues until the first part of the triangular wings 54 strike the top of the YASPEC\Loi & Tran Metal Cutting Screw CAP 040906.wpd AT/CM 4/9/M6 -7 sheet 70, which is the situation shown in Fig 4. It will be seen that the in-turned ends 56 of the wings provide a cutting surface which contacts the periphery of the hole already formed through the sheet and tends to cut away the material adjacent the hole and whilst doing this, of course, the wings are moving downwardly relative to the hole, so the hole is enlarged. It will be seen that the cutting edges 56, which were mentioned previously as being relatively small, are only in contact with the edge of the hole for a very short time, so they do not have to be extremely robust and there will generally be effectively a ribbon of material cut as the wings move downwardly through the aperture until the widest portion of the wing passes therethrough, at which time there is no further resistance by the wings acting against the sheet, the screw will continue its downward movement until the lower portion of the cup washer strikes the sheet being connected, and the screw is thus completely driven, which is the situation shown in Fig 5. Returning to the cutting action, it will be appreciated that this will be effected during only a small number of rotations of the screw, as the screw will be moving through the hole at a rate equivalent to the pitch of the thread on the screw. Also, to reinforce what was said, because of this downward movement, the cutting tip formed on the sides of the wings do not have to be hardened or treated in any other way as there is a continuous downward movement of the Y:\SPEC\Loi & Tran Metal Cutting Screw CAP 040906.wpd ATICM 4/9/06 -8 wings and thus the portion of the cutting edge which is in contact with the panel as the screw passes therethrough. It has been found that this form of screw works equally well with plastic and fibreglass sheeting as metal and has the advantage of working effectively with metal which has not been the case with previous screws of this general type. Whilst we have described the wings as being triangular and diametrically opposed on the screw body, it is to be understood that the shape of these can, if required, vary somewhat, but, generally, they have to increase in diameter towards their upper ends. The triangular shape appears to be the most satisfactory as there is a linear change in the size of the hole being cut as the screw moves downwardly. There may be some applications where, say, an arcuate outer edge may be of use which enables the cutting of the sheet to be commenced at a rate more slowly than the later removal period after the sheet has already been broached. All such variations and modifications are deemed to be within the scope of the invention and it can also be appreciated from- what has been said, the actual form of the screw, the form and method of formation of the thread can vary, the cutting tip can be of different types and the head of the screw can take different shapes or types, depending upon the application and the driving tool to be used. Y:\SPEC\Loi & Tran Metal CuLting Screw CAP 040906.wpd AT/CM 419/06

Claims

1. A screw having an elongated cylindrical body, a cutting tip formed on one end of said body, a head on the other end of said body whereby said screw is able to be rotated, and threads formed over a substantial part of the length of said body from adjacent said cutting tip, said threads being 5 adapted to advance said screw into a sheet of material when said screw is rotated in a predetermined direction of rotation, characterised in that on said body between said threads and said head there is located a pair of wings which extend from said body, and in that the radially outwardly extending edge of each of said pair of wings has an inturned portion 10 forming a cutting edge, said cutting edge extending towards said predetermined direction of rotation,

2. A screw as claimed in claim 1, characterised in that each of said pair of wings is triangular in form.

3. A screw as claimed in claim 2, characterised in that the apex of said 15 triangular form is downwardly-directed towards said cutting tip.

4. A screw as claimed in claim 1, characterised in that said radially outwardly extending edge is arcuate in form. Y;Alfred\John C\LoI & Tran Metal Cutting Screw Amended Spec 11-05-04.wpd AT/CM 415111 -10

5. A screw as claimed in any preceding claim, characterised in that each of said pair of wings is formed integrally with the body of the screw.

6. A screw as claimed in any one of claims 1 to 4, characterised in that each of said pair of the wings is formed separately and attached to said body. 5

7. A screw as claimed in any preceding claim, characterised in that said body and said pair of wings are formed of mild steel.

8. A screw as claimed in any preceding claim, characterised in that said tip is a drill point tip.

9. A screw as claimed in any one of claims 1 to 7, characterised in that said 10 tip is a tapered screw tip.

10. A screw as claimed in any preceding claim, characterised in that there is a cupped washer fitted above said pair of wings and below said head to make sealing contact with an aperture formed in said sheet of material.

11. A screw substantially as hereinbefore described with reference to the 15 accompanying drawings. Y:WAItredJohn C\Lol & Tran Metal Cutting Screw Amended Spec 11-05-04.wpd AT/CM 4/5/11 -11 DATED this 4 th day of May 2011 Loi & Tran Pty. Limited By its Patent Attorneys A TATLOCK & ASSOCIATES Y:wlfred\John C\Lol & Tran Metal Cutting Screw Amended Spec 11-OS-04.wpd AT/CM 4/6/11