AU2015200133A1

AU2015200133A1 - A Cutting Screw

Info

Publication number: AU2015200133A1
Application number: AU2015200133A
Authority: AU
Inventors: To Ha Loi
Original assignee: Loi & Tran Pty Ltd
Current assignee: Loi & Tran Pty Ltd
Priority date: 2015-01-13
Filing date: 2015-01-13
Publication date: 2016-07-28
Also published as: AU2020201841A1; AU2022200170A1; AU2020100386A4

Abstract

There is disclosed a screw (10) comprising a shank (14) having a head (12) at one end and a cutting tip (16) at the other end. A thread (15) is formed on the shank (14) and extends at least partially between the head (12) and the cutting tip (16). At least one wing member (20) is provided on the shank (14) between the head (12) and the thread (15). The at least one wing member (20) comprises a body that extends radially from the shank (14) to terminate in a distal end face (23). The distal end face (23) of the body is configured to provide a first cutting edge (23a) that extends along a leading edge thereof. The body further comprises a second cutting edge (24a) extending along a leading edge of a lower face (24) of the body. The lower face (24) of the body extending from a lower end of the distal end face (23) to the shank (14). Fi.

Description

A CUTTING SCREW

FIELD OF INVENTION

The present invention relates generally to a screw, and in particular, to a selfdrilling and cutting screw for use in securing a sheet material to an underlying batten or support surface.

BACKGROUND OF THE INVENTION

For many building applications, particularly in roofing applications, roofing materials such as shingles, tiles, or any other form of covering, are fixed to underlying battens by way of a fixing mechanism. The fixing mechanism may include a nail, screw or a clip that functions to secure the roofing materials in position such that the integrity of the roofing is maintained.

In applications where the roofing material is in the form of a sheeting material, which may be formed from a polycarbonate material or a metal, the fixing mechanism must pass through the sheeting material so as to engage with the underlying batten or support surface. This means for fixing may be complicated where the sheet material has a size that extends between adjacent battens, as the spacing between the battens may vary based on thermal expansion of the building and the battens, especially where the underlying batten is made from a metal.

For this reason cutting screws have been developed to form a hole through the sheeting material that is greater than the hole of the screw, so as to accommodate for thermal expansion and contraction in buildings. By providing such additional clearance around the securing screw, the structure is able to undergo a degree of thermal expansion and contraction while avoiding excessive forces acting directly on the sheet material via the screw. Such forces have the tendency to cause cracking and or fracture in the sheeting material around the region immediately adjacent the screw, which can cause the sheeting material to become loose and adversely affect the ability of sheeting material to function as a roofing material and be weatherproof.

The present Applicant has previously proposed such a cutting screw for this purpose which is disclosed in granted Australian Patent No. 2002214828, the entire contents of which is incorporated herein by reference. This cutting screw comprises a drilling tip and a pair of cutting wings located below the head portion of the screw that have a pair of radially extending and downwardly directed cutting portions that, when the screw is rotated, function to cut a hole through the sheeting material that has a greater diameter than the shank of the screw. The screw also accommodates a washer element between the head and the cutting wings to form a seal about the hole to prevent the ingress of water. However, while cutting wings having such a configuration are able to simply cut through synthetic materials such as polycarbonate and other plastics, such a screw has been found to be less than effective in cutting through sheeting materials made of metal.

For this reason, the present applicant has developed a cutting screw specifically configured to cut through metal sheeting which is disclosed in Australian Patent No. 2006207873, the entire contents of which is incorporated herein by reference. In this configuration, there is provide a pair of triangular or wedge shaped cutting wings that extend from the shank of the screw to provide a cutting action as the screw rotates. Each of the wedge shaped wings has a diagonal outwardly extending cutting edge that performs the cutting action as the screw progresses through the metal sheet. A problem with such a wedge shaped cutting wing is that during the initial period of contact with the metal sheeting, namely at the point where the wedge shaped cutting wing departs from the shank of the screw, deformation of the metal sheeting may occur as the screw is forced into the metal sheeting. This can have the potential of causing the metal sheeting to fold inwardly such that as the screw progresses further the cutting wing may grip the metal and cause further deformation of the material. Such a resulting action can leave sharp edges in the material and incomplete clearance about the shank of the screw, thereby defeating the very purpose of the cutting wings.

Thus, there is a need to provide a cutting screw that is capable of being used with metal sheeting that provides an efficient cutting action as the screw passes through the metal sheeting, providing sufficient clearance about the shank of the screw and ameliorating sharp edges and deformation in the surface of the metal sheeting.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided a screw comprising: a shank having a head at one end and a cutting tip at the other end; a thread formed on the shank extending at least partially between the head and the cutting tip; and at least one wing member provided on the shank between the head and the thread, the at least one wing member comprising a body that extends radially from the shank to terminate in a distal end face, the distal end face of the body is configured to provide a first cutting edge that extends along a leading edge thereof, the body further comprising a second cutting edge extending along a leading edge of a lower face of the body, the lower face of the body extending from a lower end of the distal end face to the shank.

In one embodiment, the lower face has a substantially arcuate configuration that extends from the shank to a distal point located at the lower end of the distal end face.

The distal end face may be orientated at an angle with respect to a central axis of the shank such that the body may taper inwardly from an upper end region of the distal end face to the lower end of the distal end face.

The first cutting edge may extend substantially along a length of the distal end face.

The body may comprise a top face that extends from the shank to an upper end of the distal end face and the region of intersection between the top face and the distal end face may comprise a curved shoulder portion.

In one form, a plurality of wing members may be formed on the shank, each wing member may be equispaced about the shank.

In another form, the at least one wing member(s) may be detachable from the shank.

Accordingly, in another aspect of the invention there is provided a cutting wing for a screw comprising: a body attachable to a shank of the screw so as to extend radially from the shank, the body having an upper face, an end face extending from a distal end of the upper face in a downward direction at an angle directed towards the shank, and a lower face extending from a lower end of the end face to the shank, wherein both the end face and the lower face have cutting edges formed thereon to create a hole about the shank when the screw is driven into a sheet material.

In one embodiment of this aspect of the invention, the cutting edge formed in the end face extends substantially the length of the end face.

The lower face may have an arcuate configuration that forms a substantially concave surface and the cutting edge may be formed along a leading edge of the substantially concave surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Fig. 1 is a top perspective view of a self-drilling screw in accordance with an embodiment of the present invention;

Fig. 2 is an enlarged top perspective view of the wing member of the screw of Fig. 1; and

Fig. 3 is a side view of a screw of Fig. 1 with the cupped washer installed on the shank.

DETAIFED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

The present invention will be described below in relation to its application for securing a sheet material, in particular a sheet of metal, to an underlying support such as a joist or batten in a roofing application. However, it is to be appreciated that the type of sheet material to be used with the present invention and the specific application may vary and still fall within the spirit of the present invention.

Referring to Fig. 1, there is depicted a screw 10 in accordance with an embodiment of the present invention. The screw 10 is typically employed to secure a sheet material to an underlying support (not shown). The screw 10 generally comprises a head portion 12 which is configured to engage with a driving mechanism, such as a drill or screw driver, so as to impart a rotational force to the screw 10 to cause the screw to be driven through the sheet material and into the underlying support. Whilst not shown, the upper surface of the head portion 12 may be configured to engage with the driving mechanism through a conventional manner, including a groove or indentation to facilitate engagement with a conventional screw driver or the like.

The underside of the head portion 12 may be provided with a washer element 13 that is formed integral therewith. The washer element 13 extends radially beyond the head portion 12 and presents a substantially flat undersurface for engaging with a cupped washer 30, as is depicted in Fig. 3. The cupped washer 30 is formed from a flexible material, such as a rubber material or resilient plastic material, the purpose of which will be described in more detail below. A shank 14 extends from an underside of the head portion 12 and washer element 13, with the shank 14 having a lesser diameter than the head portion 12. A thread 15 extends in a spiral manner along a surface of the shank 14 towards the tip 16. The commencement of the thread 15 is spaced a distance from the head portion 12 so as to accommodate the cupped washer 30 as well as the cutting wings 20, as will be discussed in more detail below.

The tip 16 of the screw 10 comprises a drilling edge 17 formed therein which tapers towards an end point 18. The drilling edge 17 of the tip 16 typically comprises a pair of cutting edges that extend at an angle to the central axis ‘X’ of the screw 10. A flute 19 is associated with each cutting edge to provide a path for the removal of material being cut by the cutting edges. In this arrangement, when the screw 10 comes into contact with a surface of the sheet material and the underlying support and is rotated under action of the driving mechanism, the tip 16 functions to drill a pilot hole for itself to enable the screw to penetrate into and through the sheet material and the underlying support.

As is shown in Fig. 2, a pair of cutting wings 20 extends radially from the shank 14 in the region of the shank 14 between the head portion 12 and the commencement of the thread 15. In the embodiment depicted in Figs. 1-3, two cutting wings 20 are provided at opposing locations on the surface of the shank 14. However, it will be appreciated that in other embodiments of the present invention, there may be only one cutting wing 20 or more than two cutting wings 20 located around the circumference of the shank 14.

Each of the wings 20 comprise a substantially flat and horizontally extending top portion 22; an end portion 23 that extends from the top portion 22 at an angle with respect to the central axis ‘X’ of the shank 14; and an arcuate bottom portion 24 that extends from the bottom of the end portion 23 back to the shank 14, as is depicted in Fig. 2.

The peripheral end of the top portion 22 comprises a rounded shoulder 21 that connects the top portion 22 to the end portion 23. The rounded shoulder 21 is provided to enable the screw 10 to be removed and or replaced when required. In this regard, as the hole formed through the sheeting material by the cutting wings 20 has a radius substantially equal to the width of the cutting wings 20, the rounded shoulders 21 formed at the periphery of the top portion 22 enables the cutting wings 20 to be withdrawn through the hole, without catching on the underside of the sheeting material

The leading edge 23a of the end portion 23 has a curvature formed therein, that functions to form a first cutting face. The leading edge 23a is configured, for example by a machining process or the like, such that the material immediately behind the leading edge is removed to provide a steeper cutting gradient at the leading edge to enhance material removal. Due to the angled orientation of the end portion 23, the first cutting face formed by the curved leading edge 23 a tapers radially inward from the top portion 22 to the bottom portion 24. Hence, as the screw 10 is advanced through the sheet material, the leading edge 23a of the end portion is able to gradually remove material to create a desired hole therethrough.

Similarly the leading edge 24a of the bottom portion 24 is configured, by a machining process or the like, such that the lower edge becomes the leading edge to form a second cutting face. As is more apparent from Fig. 3, the second cutting face follows the arc of the bottom portion and meets with the end portion 23 at a cutting tip 25, which defines the lowermost portion of the wing 20.

Due to the curved configuration of both the leading edge 24a of the bottom portion 24 and the leading edge 23a of the end portion 23, the cutting tip 25 projects slightly in front of the wing 20 as the screw 10 is caused to rotate about central axis ‘X’. It will be appreciated that, in situations where the screw 10 may employ more than one cutting wing 20, the curved leading edges 23 a and 24a are provided on the same side of each of the wings 20, to accommodate the rotating action of the screw 10 such that each of the wings 20 are able to combine together to facilitate cutting of the sheet material, thereby significantly reducing the load on any one wing 20.

While not shown in the Figures, the wings 20 may be detachable from the shank 14. In such an embodiment, the cutting wings 20 may be provided on a separate sleeve member that may be threadingly engaged on the shank 14.

It will be appreciated that, prior to use, a guide hole may be formed in the metal sheeting to help aid in positioning the cutting tip 25. By applying a screwing force to the head portion 12, either through the use of an electric or pneumatic tool or via a manual force, the cutting tip 25 will cut through the metal material of the sheeting and into the underlying batten. As the screw 10 continues to be driven into the batten, the cutting tip 25 of the wings 20 will come into contact with the upper surface of the sheeting material and begin a cutting motion at the lower periphery of the wing. The leading edge 24a of the bottom portion 24 will then commence to cut the surface of the sheeting material so as to distribute the initial cutting forces across the lower edge thereof as required. This will aid in providing a cleaner cut through the sheeting material minimising the generation of sharp and jagged edges about the hole formed through the sheeting material.

As the screw 10 continues to pass through the sheeting material the leading edge 23 a of the end portions 23 function to trim the periphery of the hole formed therein to provide a hole having a clean peripheral edge formed through the sheeting material. This hole can then be sealed by the cup washer 30 as the screw 10 continues to move into the batten, thereby providing a sealed hole around the shank 14 of the screw 10 that enables for a sufficient clearance about the shank 14 to accommodate expansion and contraction of the natural materials used in the roofing application.

It will be appreciated that the screw of the present invention provides an improvement over pre-existing devices in that it employs cutting wings having cutting edges along its lower surfaces and its end surfaces. This ensures that the action of the cutting wings as they are caused to rotate and pass through the material is cutting action directed along each of the edges of the wings that contact the material. This assists in sharing the cutting forces present on the cutting wings and provides for a tidier/cleaner hole formed through the material that has less material deformation about the hole and less jagged edges formed in this region. This has significant flow-on benefits as it ensures that the hole formed in the material can be easily sealed by the cupped washer and that the installation forces required to cut through the sheeting material are lower, improving the ease of use of the screws.

Throughout the specification and claims the word “comprise” and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word “comprise” and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the screw uppermost.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1. A screw comprising: a shank having a head at one end and a cutting tip at the other end; a thread formed on the shank extending at least partially between the head and the cutting tip; and at least one wing member provided on the shank between the head and the thread, the at least one wing member comprising a body that extends radially from the shank to terminate in a distal end face, the distal end face of the body is configured to provide a first cutting edge that extends along a leading edge thereof, the body further comprising a second cutting edge extending along a leading edge of a lower face of the body, the lower face of the body extending from a lower end of the distal end face to the shank.
2. A screw according to claim 1, wherein the lower face has a substantially arcuate configuration that extends from the shank to a distal point located at the lower end of the distal end face.
3. A screw according to claim 1 of claim 2, wherein the distal end face is orientated at an angle with respect to a central axis of the shank such that the body tapers inwardly from an upper end region of the distal end face to the lower end of the distal end face.
4. A screw member according to claim 1, wherein the first cutting edge extends substantially along a length of the distal end face.
5. A screw member according to claim 1 wherein the body comprises a top face that extends from the shank to an upper end of the distal end face and the region of intersection between the top face and the distal end face comprises a curved shoulder portion.
6. A screw according to any one of the preceding claims, wherein a plurality of wing members are formed on the shank, each wing member being equispaced about the shank.
7. A screw according to any one of the preceding claims, wherein the at least one wing members is detachable from the shank.
8. A cutting wing for a screw comprising: a body attachable to a shank of the screw so as to extend radially from the shank, the body having an upper face, an end face extending from a distal end of the upper face in a downward direction at an angle directed towards the shank, and a lower face extending from a lower end of the end face to the shank, wherein both the end face and the lower face have cutting edges formed thereon to create a hole about the shank when the screw is driven into a sheet material.
9. A cutting wing according to claim 8, wherein the cutting edge formed in the end face extends substantially the length of the end face.
10. A cutting wing according to claim 8, wherein the lower face has an arcuate configuration that forms a substantially concave surface and the cutting edge is formed along a leading edge of the substantially concave surface.