NZ734943A

NZ734943A - A screw fastener

Info

Publication number: NZ734943A
Application number: NZ734943A
Authority: NZ
Inventors: Hugh Marshall Bryan; Anthony Camilleri Mark
Original assignee: Illinois Tool Works
Priority date: 2016-08-31
Filing date: 2017-08-25
Publication date: 2023-12-22
Also published as: AU2021101732B4; AU2017101929B4; AU2021101732A4; AU2017219062A2; AU2022204548A1; AU2017101929A4; AU2017219062A1

Abstract

A screw fastener and the use of a screw fastener to fasten a post support bracket to a post comprising a head and an elongated shank extending from the head. The shank comprising a first section proximate the head, a threaded section and a tapered section connecting the first and the second sections of the shank. The first section is configured with a diameter greater than that of the threaded second section. The screw fastener also comprises one or more edges defined substantially about a perimeter of a region of the shank between the head and the threaded second section for providing a bore in the substrate corresponding to the diameter of the first section. The first section is located proximate the post support bracket and the bore in the substrate. The use of the screw fastener comprises fastening the post support bracket to the post by driving the or each of the one or more screw fasteners into the post such that the one or more edges of said fastener provide a bore whereby the first section is embedded within the post, the bore corresponding to the diameter of the first section.

Description

A Screw Fastener The invention relates to a screw fastener, and in particular, to a self-drilling screw fastener for use with timber substrates.

Self-drilling screws are known for fastening a wide variety of fittings to timber substrates.

The threaded configuration and drilling point of a conventional self-drilling screw is typically designed to be screwed into the timber with its head sitting flush against the fitting. However, conventional self-drilling screws are not designed to withstand high shear stress forces in use and are therefore not suitable for use in fastening applications in which the screws would be subjected to high shear stress forces, such as fastening post supports and stair tread brackets to timber substrates.

The applicant has determined that it would be advantageous to provide an improved screw fastener for coping with greater shear forces when installed. The present invention, in its preferred embodiments, seeks to at least in part alleviate the above-identified problem.

According to an aspect of the invention, there is provided a screw fastener, comprising a screw fastener for driving into a substrate, comprising a head and an elongated shank extending from the head, the shank comprising a first section proximate the head, a threaded second section, and a tapered portion connecting the first and the threaded second sections of the shank, wherein the first section is configured with a diameter greater than that of the second section; and one or more cutting edges defined substantially about a perimeter of a cutting region of the shank between the head and the threaded second section for providing a bore in the substrate corresponding to the diameter of the first section.

Preferably, the cutting region is defined by adjacent parts of the first section and the tapered portion.

Preferably, the screw fastener further comprises a flute extending towards the head from the one or more cutting edges.

Preferably, the first section is of substantially constant diameter along its length.

Preferably, the angle of the tapered portion with respect to the longitudinal axis of the shank is about 30 degrees.

Preferably, an end portion of the shank is configured with a self-drilling tip.

Preferably, the fastener is configured for use with timber.

According to another aspect of the present invention, there is provided a screw fastener, comprising a self-drilling screw fastener for driving into a substrate, comprising a head and an elongated shank extending from the head, the shank comprising a first section proximate the head, a threaded second section, and a tapered portion connecting the first and the second sections of the shank, wherein the first section is configured with a diameter greater than that of the second section; one or more cutting edges defined substantially about a perimeter of a cutting region of the shank between the head and the threaded second section for providing a bore in the substrate corresponding to the diameter of the first section, wherein the cutting region is located at a part of the tapered portion adjacent the first section.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a rendered front view showing a screw fastener according to an embodiment of the present invention; Figure 2 is a rendered partial close up view showing a cutting region of the screw fastener of Figure 1; Figure 3 is a rendered side perspective view showing the head and shank of the screw fastener of Figure 1; Figure 4 is a front view showing a screw fastener of Figure 1; Figure 5 is a top perspective view showing the screw fastener of Figure 1; Figure 6 is a bottom perspective view showing the screw fastener of Figure 1; Figure 7 is a rendered front view showing a screw fastener according to another embodiment of the present invention; Figure 8 is a rendered side perspective view showing the head and shank of the screw fastener of Figure 7; Figure 9 is a rendered perspective view showing a post support bracket fastened with the screw fastener of Figure 7; and Figure 10 is a rendered partial sectional view of the post support of Figure 9 showing the screw fastener of Figure 7 in use.

Figures 1 to 10 show preferred embodiments of screw fasteners 1 for use in fastening metal fittings such as brackets, post supports and stair tread brackets to timber substrates. More specifically, with reference to Figure 1, a fastener 1 comprises a head 10 and an elongated shank 20 extending from the head 10 for drilling into the substrate. The shank 20 has a first section 22 proximate the head 10 (referring to the portion of the shank 20 below the head 10), a threaded second section 26 and an intermediate portion 24 joining the first and second sections 22, 26 of the shank 20.

The first section 22 of the shank 20 is configured with a diameter that is greater than the diameter of the threaded second section 26. In some configurations, the first section 22 of the shank 20 has a substantially constant diameter through its length, while in other configurations the diameter of the first section 22 may be varied. It is understood that having a greater amount of fastener material in the first section 22 of the shank 20 (located immediately below the head 10) advantageously provides the fastener 1 with greater strength properties. In particular, the section of the shank 20 directly beneath the head 10 is subject to high concentrations of shear stress forces in use, and therefore increasing the diameter of the first section 22 would lead to improved shear stress force performance of the fastener 1 under load. In one configuration, the intermediate portion 24 connecting the two shank sections 22, 26 is a tapered portion, in which the tapered portion 24 gradually tapers, in the direction of the shank's longitudinal axis, from the larger diameter of the first section 22 to join with that of the second sections 26. In some configurations, as shown in Figure 4, the angle θ of the tapered portion with respect to the longitudinal axis of the shank is about 30 degrees. This relatively low taper angle facilitates a gradual transition between the two different-sized sections 22, 26 of the shank 20, thereby reducing the torque required to drive the fastener as well as reducing the likelihood of splitting the substrate during use. In another configuration, the connection between the tapered portion 24 and the threaded second section 26 is provided with a radial bend to reduce any sharp transitions between the said parts of the shank 20.

While a shank 20 with a larger first section 22 is designed to provide greater strength and shear force tolerance, the use of the fastener 1 with the larger first section 22, in the context of a self-drilling screw fastener (for use without pre-drilled holes), could potentially split or damage the substrate. Therefore, one or more cutting edges 32 are defined substantially about a perimeter of a cutting region 30 of the shank 20 between the head 10 and the threaded second section 26 for providing a bore in the substrate corresponding to the diameter of the first section 22 during use, so that the larger first section 22 can be embedded within the substrate with a reduced risk of splitting or damaging the substrate.

This may also advantageously assist the head 10 to self-align and seat tight against the fitting as the screw is fastened into the substrate. It is therefore to be appreciated that the larger first section 22 and the cutting edges 32 of the cutting region 30 work synergistically to provide a workable self-drilling screw fastener with greater shear force tolerance properties.

Referring to Figure 2, the cutting region 30 is defined by adjacent parts of the first section 22 and the tapered portion 24. The one or more cutting edges 32 are defined between a cavity 34 of the cutting region 30 and the outer surface of the shank 20. For a clockwise fastening screw, the cutting edges 32 are located on the right with the cavity 34 on the left side for storing displaced substrate. This configuration is reversed for an anti-clockwise fastening screw. In one configuration, a flute 36 extends from one or more of the cutting edges 32 for guiding and/or storing displaced substrate. Although the embodiment with flutes 36 is preferred for use with all suitable timber substrates, including softwood and hardwood, embodiments without flutes 36 is preferred to be used with softwood. While a preferred embodiment of the fastener is provided with four cutting edges 32 spaced equally about the perimeter of the cutting region 30 (partially shown in the Figures), it is to be appreciated that the fastener can be configured with one or any suitable numbers of cutting edges 32. In addition to the cutting edges 32 being defined by a cavity 34 of the cutting region 30, it is to be appreciated that the cutting edges 32 can be of any other suitable form, with non-limiting examples including cutting threads and teeth. In some embodiments, the cutting region can be located at a part of the tapered portion 24 adjacent the first section 22.

In further embodiments, the threaded second section 26 is provided with cutting threads 28. In one configuration, the cutting threads 28 are serrated to reduce the drilling torque required to screw the fastener during use. An end portion 29 of the shank 20 is provided with a self-drilling tip so that a pre-drilled hole is not required. The head 10 can be in the form of a flat washer, disc or of any other suitable form, and configured with a cap 12 and/or a drive recess/socket 14, for example in the form of a star drive recess/socket as depicted in Figure 3, for receiving suitable corresponding screw drivers.

Figures 7 to 8 depicts a further embodiment in which the threaded second section 26 is preceded by a length-extending portion 27 located intermediate the tapered portion 24 and the second section 26. In this embodiment, the tapered portion 24 joins the first section 22 and the extended portion 27. The extended portion 27 has a diameter smaller than the first section but greater than the threaded second section 26. A second tapered portion 27A can be provided to connect the extended portion 27 and the second section 26.

Figures 9 to 10 show screw fasteners 1 as depicted in Figures 7 to 8 being fastened to a post bracket 2 through a hardwood substrate 3. It is to be appreciated that the enlarged first section 22 of the fastener 1 is located proximate the bracket 2 and the bore hole for providing improved strength in this area under shear force loading.

It is to be noted that the above-described features of a enlarged first section 22 of the shank with a cutting region 30 are not only suitable for a self-drilling screw fastener, it is equally suitable for non-self-drilling screws, with a non-limiting example such as coach screws. Further, preferred embodiments of the fastener 1 is not only suitable for use with timber substrates as described (including softwood and hardwood), it is equally suitable for use with other construction substrates.

In the description and drawings of this embodiment, same reference numerals are used as have been used in respect of the first embodiment, to denote and refer to corresponding features.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A screw fastener for driving into a substrate, comprising: a head and an elongated shank extending from the head, 5 the shank comprising a first section proximate the head, a threaded second section, and a tapered portion connecting the first and the second sections of the shank, wherein the first section is configured with a diameter greater than that of the threaded second section; and one or more cutting edges defined substantially about a perimeter of a 10 cutting region of the shank between the head and the threaded second section for providing a bore in the substrate corresponding to the diameter of the first section.

2. A screw fastener according to claim 1, wherein the cutting region is defined by adjacent parts of the first section and the tapered portion.

3. A screw fastener according to either claim 1 or claim 2, further comprising a flute extending towards the head from the one or more cutting edges.

4. A screw fastener according to any one of preceding claims, wherein the first 20 section is of substantially constant diameter along its length.

5. A screw fastener according to any one of preceding claims, wherein the angle of the tapered portion with respect to the longitudinal axis of the shank is about 30 degrees. 25

6. A screw fastener according to any one of preceding claims, wherein an end portion of the shank is configured with a self-drilling tip.

7. A screw fastener according to any one of preceding claims, wherein the fastener is configured for use with timber. H:\azh\Interwoven\NRPortbl\DCC\AZH\15252374_1.docx-25/