AU2005201731B2

AU2005201731B2 - A screw with a double thread and a recess in the side of the shank

Info

Publication number: AU2005201731B2
Application number: AU2005201731A
Authority: AU
Inventors: Morten Friis Buhl
Original assignee: ITW Construction Products ApS
Current assignee: ITW Construction Products ApS
Priority date: 2005-04-26
Filing date: 2005-04-26
Publication date: 2007-08-09
Anticipated expiration: 2025-04-26
Also published as: AU2005201731A1

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S):: ITW Construction Products ApS ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Nicholson Street,Melbourne, 3000, Australia INVENTION TITLE: A screw with a double thread and a recess in the side of the shank The following statement is a full description of this invention, including the best method of performring it known to me/us:- APR,.2005 13:30 CHAS HUDE PATENT NO. 1262--P. la Techical Field Te invention relates to a screw with. a double thread and a recess I h ieo h shank.i hesd o h l34AcRundArt It is a well-known fact that screws have a tendency to spread the wood fibres instead of sa d woo fib es epecially w hen said screw s ae Used close t i e o piee wodandacordinigly said screws have a tendency to split said wood on b oth sides, of the Screw. As a result, not only the wood is destroyed, but the tighteninggri ofth scew n he oodismuch too Poor. When the fibres are not cut UP dringtheInsertion of the screw, said fibres are arranged as a bow surrounding the core 0'the screw, As a result,'the screw is subjected to an intense pressure which intur liv~ves'a high frictIon cOUftmrtJg the screwing movemenL In addition, it is known to provide screws withareeslvngapronfth cre wihou theas arld eitendiug into the shank of. said screw. Such a single re- cess does,,not s the: necessay cutting up of the WOOd fibres during the screwing Disclosure of Invention The object of the invention is to Provide a screw which efficientyct ptewo fibr s d rin th sc e wi~ g ov e ml en t and w h ich av oid s a sp littin g of said w ood d uring the screwing rnoveneint PI:OPERUPMI 2602390 1spa dcL0A712007 -2- In accordance with one aspect of the present invention there is provided a screw comprising: a double thread; and two recesses arranged diametrically opposite one another on a radial side portion of a shank of the screw, each of the two recesses being shaped as two plane segments extending substantially parallel to an axis of the screw and along a portion of the shank and located (ti so that a portion of the double thread in which the recesses are formed divides the remainder of the double thread into first and second uninterrupted portions one of which extends from the recess to a tip of the screw.

In accordance with another aspect of the present invention there is provided a screw comprising: a double thread; and recess means arranged diametrically opposite one another on a radial side portion of a shank of the screw at a distance distal from a tip of the screw shank for forming wood cutting edges which are configured to cut wood fibers and for providing a space wherein wood fibers can nestle in a manner that attenuates a tendency for the wood, into which the screw is screwed, to split.

As a result two cut surfaces are provided, where the two cutting edges thereof are arranged diagonally opposite one another while a clearance is simultaneously established, said clearance being positioned ahead of the cutting edges during the screwing movement. As a result, the wood fibres have a tendency to nestle against the plane surfaces of the recesses between the thread-cutting edges prior to meeting the succeeding two cutting edges which efficiently cut up the wood fibres in such a manner that the risk of a splitting of the wood has been minimized. The recesses are suitably of such a length that they extend from the tapering portion of the screw and a short distance over a portion where the root diameter of the screw presents the same size everywhere. A double thread renders it possible to keep the length of the recess relatively short in such a manner that the strength and retaining force of the screw are not significantly reduced.

P %OPERUPM1260239D spa docIOA7I2)7 -3- According to a particularly advantageous embodiment of the invention, each recess can cut off from approximately 0.15 mm to approximately 0.5 mm of the core diameter extending perpendicular to the plane side of the recess farthest away from the tapered end of the screw.

Finally, the recesses may extend up to a distance of from approximately 6.0 mm to approximately 14.0 from the tapered end of the screw, whereby it is ensured that a suitably good result is obtained in connection with most screw dimensions.

Brief Description of the Drawings The invention is explained in detail below with reference to the drawings, in which FIG. 1 is a front view of a portion of a screw according to the invention, and FIG. 2 is a side view of the portion of FIG. 1.

Best Mode for Carrying out the Invention The screw shown in the drawing includes two threads 1 and 2 extending in parallel and around the core 3 of the screw from a tapered end 4.

A plane recess 5, 6 is provided on each side of the screw, said recesses extending parallel to one another and parallel to the axis of the core. The recesses extend at such a distance from the axis of the core 3 that a segment of the core is cut off, said segment being of a maximum height a in the range of from approximately 0.15 mm to approximately 0.5 mm.

The plane recesses 5 and 6 extend from the tapered area of the screw in such a manner that the end adjacent the tapered end 4 also extends through the portions of the threads 1 and 2 within this area. Subsequently, the recesses 5 and 6 extend upwards to a length b of from approximately 6.0 mm to approximately 14.0 mm from the tapered end of the screw. As a result, two threaded cutting edges 7, 7 are provided along the sides of the recesses 5 and 6, P \OPERUPAIZM62390 Il. doc.-lO/7f2(X)7 -4said threaded cutting edges cutting up the wood fibres during the screwing movement of the screw.

The above ranges of the lengths a and b depend on the dimension of each screw, as two 5 threaded cutting edges 7 and 8 should, if possible, always be provided along the rim of the recess.

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.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

1. Screw comprising: a double thread; and 5 two recesses arranged diametrically opposite one another on a radial side portion of a shank of the screw, each of the two recesses being shaped as two plane segments extending substantially parallel to an axis of the screw and along a portion of the shank and located so that a portion of the double thread in which the recesses are formed divides the remainder of the double thread into first and second uninterrupted portions one of which extends from the recess to a tip of the screw.

2. A screw according to claim 1, wherein a depth of each of the two recesses is approximately 0.15 mm to approximately 0.5 mm taken along a core diameter of the screw shank.

3. A screw according to claim 1, wherein each of the two recesses extend along the screw shank to a location which is approximately 6.0 mm to approximately 14.0 from the tip of the screw.

4. A screw according to claim 2, wherein each of the recesses extend along the screw shank to a location which is approximately 6.0 mm to approximately 14.0 from the tip of the screw.

A screw according to claim 1, wherein the screw has a tapered shank portion and a non-tapered shank portion, the tapered shank portion extending from the tip of the screw to the non-tapered shank portion, and wherein the recesses are formed in at least the non- tapered shank portion so that a root diameter of the screw presents the same size along the non-tapered portion of the shank in which the two recesses are formed.

6. A screw according to claim 1, wherein the screw comprises a wood screw. P AOPERUVPM12602390 I pl doc- I )7/207 -6- c-

7. A screw according to claim 1, wherein the two recesses interrupt the double screw thread in a manner wherein a plurality of cutting edges, which are configured to cut wood fibers, are formed on the interrupted portion of the double screw thread and which provides a space in which wood fibers can nestle against plane surfaces of the two recesses in a 5 manner that attenuates a tendency for the wood into which the screw is screwed, to split.

8. Screw comprising: N, a double thread; and recess means arranged diametrically opposite one another on a radial side portion of a shank of the screw at a distance distal from a tip of the screw shank for forming wood cutting edges which are configured to cut wood fibers and for providing a space wherein wood fibers can nestle in a manner that attenuates a tendency for the wood, into which the screw is screwed, to split.

9. A screw, substantially as hereinbefore described with reference to the accompanying drawings.