GB2562457A

GB2562457A - A screw

Info

Publication number: GB2562457A
Application number: GB1703844.9A
Authority: GB
Inventors: Rudge Arthur; Whitton Paul
Original assignee: METPRO Ltd
Current assignee: METPRO Ltd
Priority date: 2017-03-10
Filing date: 2017-03-10
Publication date: 2018-11-21
Also published as: GB201703844D0

Abstract

A screw 1 comprises a shank 2 having a regular polygonal or polylobal cross-section of six or more sides or lobes along at least a portion of the shank 2. The screw 1 may be a self-tapping or thread forming screw. The shank 2 may be hexagonal or hexalobal along at least 50% of its length.

Description

(71) Applicant(s):

MetPro Ltd (Incorporated in the United Kingdom) Unit 4, Summit Crescent Industrial Estate, Smethwick, West Midlands, B66 1BT, United Kingdom (72) Inventor(s):

Arthur Rudge

Paul Whitton (74) Agent and/or Address for Service:

Wilson Gunn

Charles House, 148/9 Great Charles Street, BIRMINGHAM, B3 3HT, United Kingdom (54) Title of the Invention: A screw

Abstract Title: Screw with polygonal or polylobal shank (57) A screw 1 comprises a shank 2 having a regular polygonal or polylobal cross-section of six or more sides or lobes along at least a portion of the shank 2. The screw 1 may be a self-tapping or thread forming screw. The shank 2 may be hexagonal or hexalobal along at least 50% of its length.

(51) INT CL:

F16B 25/00 (2006.01) (56) Documents Cited:

GB 1494015 A GB 1146377 A

WO 2006/043169 A1 (58) Field of Search:

INT CL F16B

Other: WPI, EPODOC, Patents Fulltext

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A SCREW

Technical Field of the Invention

The present invention relates to screws. In particular, the present invention relates to thread forming screws comprising a hexagonal shank.

Background to the Invention

It is known in the art to provide screws, such as thread-forming screws and thread-cutting screws, comprising a shank (sometimes called a shaft), a thread and a head. The head further comprises a drive which allows a tool, such as a screwdriver to turn the screw, in use.

Thread forming screws are rotated around their major axis in order to drive the screw into a pre-formed cavity. The thread of the thread forming screw displaces surrounding material to form a mating thread in the material it is driven into.

Most screws have a shank of circular cross-section capped by a head of circular or hexagonal cross-section (so-called “hex head” screws).

It is also known in the art to provide such thread forming screws comprising a shank having a three-lobed, or substantially triangular cross-section. The triangular cross-section of the shank may reduce the torque required to form the mating thread, and may reduce friction during forming and reduces vibrational loosening compared to a thread forming screw comprising a circular shank.

However, thread forming screws comprising a three-lobed or triangular crosssectional shank still suffer from problems, including; requiring a relatively high starting and end pressure; the three-lobed screw form does not hold in thin sheet steel due to material contact in only three areas, and three-lobed screws tend to pull through the sheet metal and strip; the starting ability of the screw may be inconsistent; chips may form inside the cavity which the screw forms due to the relatively high frictional forces generated; and a relatively high torque is still required to turn the screw, even if this may be lower than conventional screws.

It is therefore the aim of an embodiment or embodiments of the present invention to overcome or at least partially mitigate at least one problem associated with the prior art.

Summary of the Invention

According to a first aspect of the invention there is a screw comprising a shank comprising a regular polygonal or polylobal cross-section of six or more sides or lobes along at least a portion of the shank.

For the avoidance of doubt, the term “polylobal” or “multi-lobular” means having a plurality of lobes. The term polylobal also includes the synonym “multi-lobal”.

The shank may comprise a hexagonal, hexalobal, heptagonal, heptalobal. octagonal, octalobal, nonagonal, nonalobal, decagonal, decalobal, undecagonal, undecalobal, dodecagonal, dodecalobal, icosagonal or icosalobal cross-section but is preferably hexagonal or hexalobal.

The shank may comprise a polygonal or polylobal shape, preferably hexagonal or hexalobal, of any suitable dimensions. The shank may comprise a substantially constant polygonal or polylobal, preferably hexagonal or hexalobal cross-section, along the length of the shank or the cross-section may vary in size or shape along the shank. The polygonal or polylobal, preferably hexagonal or hexalobal, cross-section allows a smoother start to the thread forming process over currently preferred triangular shanks. The hexagonal or hexalobal shape also improves resistance to vibrational loosening properties compared to circular or trilobular shanks.

The shank may comprise one or more areas along the length of the shank with a cross-section not comprising a regular polygonal or polylobal cross-section of six or more sides, but preferably the shank comprises a regular polygonal or polylobal crosssection of six or more sides along at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or substantially 100% of its length.

The screw may be a thread-forming screw or a thread-cutting screw, but is preferably a thread-forming screw.

Adjacent sides of the polygonal or polylobal shank may meet at a vertex or linear edge along the shank, or may form rounded corners or vertices, such that the cross-section has a multi-lobular shape. Thus, in some embodiments there is provided a screw comprising a lobular cross-section with at least six lobes. Preferably the shank comprises a hexalobular cross-section along at least a portion of its length and preferably along at least 50%, 75% or 90% of its length.

The shank may be of any suitable length and diameter. The shank may be less than 10mm in length, or at least 10mm in length, or at least 20mm, or at least 50mm, or at least 100mm, or at least 200mm. The diameter or width of the shank may be less than 5mm, or at least 5mm, or at least 10mm, or at least 20mm.

The shank comprises an external threaded region along at least a portion of its length. The thread may comprise any suitable major and minor diameter, and may further comprise any suitable pitch. The thread may extend along the entire length of the shank, or the thread may only extend along a proportion of the shank. The thread may extend along up to or equal to 10% of the shank, or over 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% of the shank. The shank may comprise one or a plurality of regions wherein no thread is present.

The thread may comprise an ISO metric screw thread, as defined in international standard ISO 68-1 and preferred combinations of diameter and pitch are listed in international standard ISO 262. Suitable ISO metric screw thread sizes include Ml.6, M2, M2.5, M3, M4, M5, M6, M7, M8, M10, 12, ,14, M16, M18, M20, M22, M24, M27, M30, M33, M36, M39, M42, M45, M48, M52, M56, M60, M64 and M 68.

In some embodiments, the shank may comprise a tapered end region. The tapered end region may taper at any suitable angle, and may form an end of any suitable size and shape. The tapered end may comprise an end face of a different shape to a regular polygonal or polylobal cross-section of six or more sides or lobes. The end face may be circular, triangular, square or any other suitable shape. Alternatively, the tapered end may comprise an apex or cutting point. The tapered end in combination with the regular polygonal or polylobal cross-section, preferably hexagonal or hexalobal, shape of the shank allows a more positive alignment with the mating component over currently triangular cross-sectional or trilobular shanks (or indeed, regular circular cross-sectional shanks).

In some embodiments, the screw may comprise a head. The head may be of any suitable cross-sectional shape, such as substantially circular or hexagonal, for example.

The head may be a pan head, dome head, round head, button head, mushroom (truss) head, flat head, countersunk head, oval head, raised head or flanged-head, for example.

The head may comprise a drive, which may be selected from a slot, cross-head, Phillips, Pozidriv, Frearson, square, Robertson, hex, 12-point flange, hex socket (Allen), pin-in-the-hex-socket, torx, security torx, tri-wing, torq-set, spanner-head (pig nose), clutch, one-way, double-square, triple-square, polydrive, spline drive, double hex, Bristol, pentalobe or hexalobe drive, for example.

The screw, shank and head may comprise any suitable material, such as steel, for example.

According to a second aspect of the invention there is provided use of a screw of the first aspect of the invention to secure two items together. At least one item may be a metal item, such as a sheet metal item, and both items may be metal items.

According to a third aspect of the invention there is provided a method of securing two items together, using the screw of the first aspect of the invention.

The method may comprise the step of forming a hole through both items, inserting the screw into the hole one item and then forming a thread in the hole of the other item using the screw. Alternatively, the method may comprise placing both items adjacent to each other and forming a thread through both items using the screw. Alternatively, the method may comprise the step of forming a hole in one item; placing said item against the other item such that they abut; inserting the screw into said hole in said item; and forming a hole and thread in the other item using the screw. At least one item may be a metal item, such as a sheet metal item.

Detailed Description of the Invention

In order that the invention may be more clearly understood embodiments will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1 is a side view of an embodiment of the screw of the invention, showing the shank with no screw-thread shown;

Figure 2 is a perspective view of the embodiment of Figure 1 with a screwthread around the shank of the screw;

Figure 3 is a top view of the screw of Figure 1;

Figure 4 is a cross-sectional view of the screw of Figure 1 through the line AA; and

Figure 5 is a cross-sectional view of an alternative embodiment of a shank and screw thread, in which the shank has a hexalobal cross-section.

With reference, firstly to Figures 1 and 2, a screw 1 of the invention comprises a hexagonal shank 2, which has a substantially constant hexagonal cross-section and a head 4 attached to the top of the shank 2. The shank 2 extends from the head 4 to the end of the screw 10. The head 4 is substantially domed in shape, comprising a domed body and a substantially planar lower face to which the shank 2 is connected. The shank 2 comprises a tapered end region 8 extending to its free end 10. The end 10 is hexagonal in shape and substantially planar. The screw 1 further comprises a helical screw thread 6, which extends from the head 4 to the end 10.

Figure 3 illustrates a top view of the screw 1. The head 4 comprises a hexalobular drive 12 in the top surface thereof. The drive 12 allows a compatible tool to be inserted in order to assist in the turning of the screw 1.

Figure 4 illustrates a cross-sectional view of the screw 1 through the line A-A of Figure 3. This shows the hexagonal shape of the shank 2, in relation to the thread 6. The edges of the shank 2 are shown to be substantially straight, forming corners with adjacent edges.

Figure 5 illustrates a cross-sectional view of an alternative embodiment of a shank 22 and screw-thread 6, in which the shank has a hexalobal cross section.

In an alternative embodiment the thread 6 may not extend along the entire length of the shank 2; for example it may end before the tapered end region 8 or may start some way down the shank 2 from the head 4.

In other embodiments, the shank of the screws of the invention may comprise more than six sides or lobes, and so may comprise portions of the shank or the whole of the shank, which comprise 7, 8, 9, 10, 11, 12 or 20 sides or lobes, for example.

The screw 1 of the invention shown in Figures 1 to 5 may comprise an end terminated in an apex or cutting point, rather than the flat end 10 shown in the Figures.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. A screw comprising a shank comprising a regular polygonal or polylobal crosssection of six or more sides or lobes along at least a portion of the shank.

2. A screw as claimed in claim 1 wherein the shank comprises a hexagonal or hexalobal cross section.

3. A screw as claimed in claim 1 or 2 wherein the screw comprises a tapered end region.

4. A screw as claimed in any preceding claim wherein the shank comprises a polygonal or polylobal region which extends at least 50% of the length of the shank.

5. A screw as claimed in any preceding claim wherein the thread of the screw extends along at least 50% of the length of the polygonal or polylobal crosssection region of the shank.

6. A screw as claimed in any preceding claim wherein the shank comprises a polygonal or polylobal region which extends at least 75% of the length of the shank and the thread of the screw extends along at least 75% of the length of the polygonal or polylobal region.

7. Use of a screw of any one of claims 1 to 6 to secure two or more items together.

8. A method of securing two or more items together using the screw of any one of claims 1 to 6.

9. A method or use as claimed in claim 7 or 8 wherein at least one item comprises metal.

10. A method or use as claimed in claim 9, wherein the metal is sheet metal.

11. A method as claimed in claim 9 or 10, wherein the screw forms at thread at least partway through the metal.

Intellectual

Property Office

Application No: GB1703844.9