GB2251666A - "Screws for roofing sheets" - Google Patents

"Screws for roofing sheets" Download PDF

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Publication number
GB2251666A
GB2251666A GB9122612A GB9122612A GB2251666A GB 2251666 A GB2251666 A GB 2251666A GB 9122612 A GB9122612 A GB 9122612A GB 9122612 A GB9122612 A GB 9122612A GB 2251666 A GB2251666 A GB 2251666A
Authority
GB
United Kingdom
Prior art keywords
threaded portion
screw
pitch
roof
length
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9122612A
Other versions
GB9122612D0 (en
Inventor
Nicolaas Hendrik Arnold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Council of Scientific and Industrial Research CSIR
Original Assignee
Council of Scientific and Industrial Research CSIR
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Council of Scientific and Industrial Research CSIR filed Critical Council of Scientific and Industrial Research CSIR
Publication of GB9122612D0 publication Critical patent/GB9122612D0/en
Publication of GB2251666A publication Critical patent/GB2251666A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
    • F16B25/0042—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw
    • F16B25/0073—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw characterised by its pitch, e.g. a varying pitch
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04D—ROOF COVERINGS; SKY-LIGHTS; GUTTERS; ROOF-WORKING TOOLS
    • E04D3/00—Roof covering by making use of flat or curved slabs or stiff sheets
    • E04D3/36—Connecting; Fastening
    • E04D3/3605—Connecting; Fastening of roof covering supported directly by the roof structure
    • E04D3/3606—Connecting; Fastening of roof covering supported directly by the roof structure the fastening means being screws or nails
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/001—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed
    • F16B25/0031—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed the screw being designed to be screwed into different materials, e.g. a layered structure or through metallic and wooden parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
    • F16B25/0042—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw
    • F16B25/0057—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw the screw having distinct axial zones, e.g. multiple axial thread sections with different pitch or thread cross-sections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/10—Screws performing an additional function to thread-forming, e.g. drill screws or self-piercing screws
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B5/00—Joining sheets or plates, e.g. panels, to one another or to strips or bars parallel to them
    • F16B5/02—Joining sheets or plates, e.g. panels, to one another or to strips or bars parallel to them by means of fastening members using screw-thread
    • F16B5/0275—Joining sheets or plates, e.g. panels, to one another or to strips or bars parallel to them by means of fastening members using screw-thread the screw-threaded element having at least two axially separated threaded portions

Abstract

A screw 10 comprises a head 20, a first thread 12 having a first pitch 14, a second thread 18 having a second pitch 18 which is greater than the first pitch 14, and a first unthreaded portion 24, in order to improve securing and thus sealing of roof shoots 30, 32, 34, 36 to an underlying wooden or metal beam 38. The second pitch 18 is between 1.01 and 4 times the first pitch 14, and the length of the first thread 12 is between 1.01 and 4 times the length of the second thread 18. A cylindrical spacer 28 is provided to engage a flexible seal (not shown). <IMAGE>

Description

FIELD OF INVENTION This invention relates to fasteners. Nore particularly, the invention relates to a screw suitable for securing one object to another.
BACKGROUND OF THE INVENTION Water penetration past conventional roof fasteners and metal roofing sheets is a problem in the building industry. Various screws and seals and combinations thereof are used for fixing roof sheeting in such a way as to attempt to prevent the entry of rain water. However, many of the prior art seals still allow water penetration.
A large proportion of this water penetration could be prevented if the screw was designed in such a manner that the roofing sheets, sealing washer and screw head were mounted in permanent contact with one another and thus in a sealed condition for the life of the roof.
In the process of driving the roof screws through the roof sheets, the sheets are bent and/or dented particularly the bottom sheet(s) in areas where they overlap and, because the screws are normally only driven through the ridges of the corrugated iron sheets, where they are unsupported in their immediate vicinity, small valleys are formed around the screws in the regions where they are driven through the roof sheets. Gaps usually also exist between the roof screws and the surrounding roof sheet material. In the absence of effective sealing means around the roof screws, these valleys or indentations may contibute to rain water passing through the gaps, some of which could penetrate the timber into which the roof screws are secured, causing the timber to swell and eventually to decay with a result that the roof screws become loose.
There accordingly exists a need for a fastener which either totally prevents or at least partially reduces the possibility of leakages from occurring through a gap between the fastener and the surrounding roof sheet material.
SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a substantially cylindrically shaped screw comprising a head at one end thereof, a first threaded portion having a first pitch at the opposite end thereof, a second threaded portion having a second pitch which is greater than the first pitch and which is located intermediate the first threaded portion and the head, and a first unthreaded portion intermediate the head and the second threaded portion. The end opposite the head is preferably pointed, so as to facilitate its penetration through a roof sheet and into a support means. In addition or as an alternative, the end may be provided with one or more and/or self-tapping cutting edges, to facilitate its entry into hard substances such as iron or steel.
Thus the screw may be driven or screwed through the roof sheet by means of respectively a hammer or a screw driver or similar tool.
The second pitch may vary from about 1,01 times to about 4 times, more preferably from about 1,25 times to about 2,0 times the first pitch.
In a preferred embodiment of the invention, the second pitch is about 1,5 times the first pitch.
In the context of a roof screw, i.e. a screw to be used for securing a roof plate to a support means, the first pitch is preferably about 3,5mm and the second pitch is preferably about 5,25mm.
The length of the first threaded portion may vary from about 1,01 times the length of the second threaded portion, to about 4 times the length of the second threaded portion.
In one embodiment of the invention, the length of the first threaded portion only just exceeds 1,5 times the length of the second threaded portion. However, the length of the first threaded portion should preferably still be long enough for proper securing of the roof sheet into the support means.
Alternatively, the lengths of the first and second threaded portions may be selected such as to suit the conditions of a specific profile and of a specific material to which the roof sheet is to be secured.
For example, in a case where South African pine is to be used as a support for the roof sheet, it has been found that a length of + 50mum for the first threaded portion yields good results (to firmly anchor the roof sheet in the wood). For a single IBR sheet having a crown height of + 38mm, a length for the second threaded portion of from a minimum of about 20mm to a maximum of about 36mm (i.e. slightly less than the crown height) is required to ensure that, even if the IBR sheet is badly bent down when the roof screw is screwed therethrough, the second threaded portion will still lift the IBR sheet to approximately its original position. The length of the first threaded portion preferably exceeds the ratio which the first pitch forms to the second pitch multiplied by the crown height of the roof sheet.
The crown height is the distance between the crowns or ridges and the valleys of the roof sheet.
In order to facilitate manufacture of the screw, it may also comprise a second unthreaded portion located between the first threaded portion and the second threaded portion.
Conveniently, the minor diameter of the first threaded portion is the same as that of the second threaded portion, the first unthreaded portion and the second unthreaded portion. In the context of a roof screw, the minor diameter is preferably about 6mm, but may vary between about 1,Omm and about 20mm.
The crest or major diameter of the first threaded portion may be the same as or different from that of the second threaded portion.
In the context of a roof screw, this diameter is preferably about 8mm but may vary between about 1,5mm and about 35mm.
Also according to the invention, the screw may comprise a cylindrically shaped spacer portion located between the head and the first unthreaded portion, the diameter of the spacer portion being larger than that of the minor diameter, preferably even slightly larger than the major diameter of the first threaded portion and that of the second threaded portion so that the spacer portion may serve as a shoulder against which the roof sheet or roof sheets may be pushed once the screw has been screwed into the support means.
The length of the spacer portion is preferably selected such that it is only slightly less than the thickness or height of a flexible seal so that the seal will be compressed when the screw is screwed down into the support means. On the other hand, the flexible seal should not be compressed too much, because excessive deformation may give rise to leakage which could either happen as a result of such excessive deformation that the seal leaks ab initio or as a result of rapid deterioration of the seal after installation.
Depending on the material of construction and the geometry of the seal, we have found that the length of the spacer portion may be varied from about 20% of the thickness or height of the seal, to about 100% thereof, more preferably from about 40% to about 98% thereof and still more preferably from about 45% to about 95% thereof.
The length of the first unthreaded portion may vary widely from close to 0, say O,1mm, to several times the diameter of the screw.
Conveniently, its length is such as to accommodate at least one, preferably at least two and more preferably, at least four roof sheets. In this context, allowance should be made for the fact that the roof sheets often are deformed when the screw is driven therethrough, so that the space taken up by a single roof sheet may be as much as up to three to four times its thickness, and even more.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings in which: - Figure 1 shows a part sectional elevational view of a screw in accordance with the invention, the lower part of which is partly screwed into a wooden beam; and - Figure 2 shows the screw of Figure 1 in a position in which it has been fully screwed down.
DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings, reference numeral 10 generally indicates the screw.
The screw 10 comprises a first threaded portion 12 having a first pitch 14 and a second threaded portion 16 having a second pitch 18, which is 1,5 times the first pitch 14.
As appears from the drawings, the screw 10 is of a substantially cylindrical shape and comprises a head 20 at its one end and a pointed tip 22 at its other end.
The first threaded portion 12 extends from the tip 22 to a position intermediate the tip 22 and the head 20 and the second threaded portion 16 is located between the first threaded portion 12 and the head 20.
The screw 10 further comprises a first unthreaded portion 24 located between the second threaded portion 16 and the head 20, as well as a second unthreaded portion 26 located between the first threaded portion 12 and the second threaded portion 16.
Both the minor diameter and the crest or major diameter of the first threaded portion 12 is the same as that of the second threaded portion 16. In addition, in order to avoid excessive stresses on the transition from a threaded portion to an unthreaded portion and vice versa, the minor diameters of the first and second threaded portions are the same as the diameter of the first and second unthreaded portions.
The screw 10 further comprises a cylindrical spacer portion 28 located between the head 20 and the second unthreaded portion 16, for locating a seal (not shown) and for preventing excessive compression thereof.
As is shown in the drawings, the screw 10 extends through roof sheets 30, 32, 34, 36 into a beam 38.
In Figure 1, the screw 10 is shown as having penetrated the roof sheets 30, 32, 34, 36 and it is beginning to enter the wooden beam 38, whilst in Figure 2, the screw 10 has been screwed down fully.
In use, a pilot hole is drilled through the ridge or ridges of one, two or four roof sheets in a position in which they are to be secured to an underlying wooden or metal beam, such as the wooden beam 38. As a result of the drilling action, the bottom most roof sheet 30 could be bent such that its free end 30.1 is spaced from the roof sheet 32, as is shown in Figure 1. If sufficient pressure is exerted when the pilot hole is drilled (or sometimes even punched) or when the screw 10 is driven through the roof sheets 30 to 36 by means of a hammer, the sheets 32, 34 and 36 may be dented and/or bent in the region of the hole such as to form localised valleys.
The first threaded portion 12 of the screw 10 is then screwed into the hole until it eventually engages with the beam 38, as is shown in Figure 1. Soon afterwards, the trailing end of the first threaded portion disengages with the roof sheets 30 to 36 whereafter the leading end of the second threaded portion begins to engage with them. Upon further turning of the screw 10, the second threaded portion 16 begins to lift the roof sheets 30 to 36, because the pitch 18 of the second threaded portion 16 is greater than the pitch 14 of the first threaded portion 12. The roof sheets 30 to 36 are lifted one by one until eventually they disengage with the trailing end of the second threaded portion 16 and are "stored" in the region of the first unthreaded portion 24 (see Figure 2). As can also be seen from Figure 2, the end 30.1 of the roof sheet 30 has now been urged back against the sheet 32.
Conveniently, the length of the first unthreaded portion 24 is selected such that it can accommodate four roof sheets 30 to 36.
In order to time the disengagement of the roof sheets 30 to 36 from the second threaded portion 16, the length of the second threaded portion 16 is conveniently selected such as to be somewhat less than the crown height of the roof sheets 30, 32, 34 and 36.
The length of the first threaded portion 12 is selected such as to slightly exceed the distance between the crest of the top roof sheet 36 and the top of the beam 38.
The claims which follow are to be considered an integral part of the disclosure.

Claims (10)

1. A substantially cylindrically shaped screw comprising a head at one end thereof, a first threaded portion having a first pitch at the opposite end thereof, a second threaded portion having a second pitch which is greater than the first pitch and which is located intermediate the first threaded portion and the head, and a first unthreaded portion intermediate the head and the second threaded portion.
2. A screw as claimed in claim 1, in which the end opposite the head is pointed so as to facilitate its penetration through a roof sheet and into a support means.
3. A screw as claimed in claim 2, in which the end is provided with a cutting edge.
4. A screw as claimed in claim 1, in which the second pitch varies from about 1,01 times to about 4 times the first pitch.
5. A screw as claimed in claim 1, in which the length of the first threaded portion varies from about 1,01 times the length of the second threaded portion, to about 4 times the length of the second threaded portion.
6. A screw as claimed in claim 2, in which the length of the first threaded portion exceeds the ratio which the first pitch forms to the second pitch multiplied by the crown height of the roof sheet.
7. A screw as claimed in claim 1, comprising a second unthreaded portion located between the first threaded portion and the second threaded portion.
8. A screw as claimed in claim 7, in which the minor diameter of the first threaded portion is the same as that of the second threaded portion, the first unthreaded portion and the second unthreaded portion.
9. A screw as claimed in claim 1, in which the major diameter of the first threaded portion is the same as that of the second threaded portion.
10. A screw as claimed in claim 8, comprising a cylindrically shaped spacer portion located between the head and the first unthreaded portion, the diameter of the spacer portion being larger than that of the minor diameter.
GB9122612A 1990-11-02 1991-10-24 "Screws for roofing sheets" Withdrawn GB2251666A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ZA908791 1990-11-02

Publications (2)

Publication Number Publication Date
GB9122612D0 GB9122612D0 (en) 1991-12-04
GB2251666A true GB2251666A (en) 1992-07-15

Family

ID=25580371

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9122612A Withdrawn GB2251666A (en) 1990-11-02 1991-10-24 "Screws for roofing sheets"

Country Status (2)

Country Link
AU (1) AU649736B2 (en)
GB (1) GB2251666A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996022472A1 (en) * 1995-01-18 1996-07-25 Grk Canada Ltd. A screw
EP0849474A1 (en) * 1996-12-17 1998-06-24 MiTek Industries GmbH Drill screw
WO1999015796A1 (en) * 1997-09-22 1999-04-01 Sfs Industrie Holding Ag Screw for fixing wooden laths on a roof substructure or a wall foundation
DE29805784U1 (en) * 1998-03-30 1999-08-05 Sfs Ind Holding Ag Screw for fastening wooden slats to a roof or wall substructure
DE20003705U1 (en) * 2000-02-29 2001-07-12 Sfs Ind Holding Ag Heerbrugg Connection of two wooden beams that adjoin one another at least approximately at right angles
GB2397105A (en) * 2003-01-07 2004-07-14 Altenloh Brinck & Co Self tapping screw having two threads of differing pitch
GB2428761A (en) * 2005-08-01 2007-02-07 Michael Wilkinson Screw
US7255523B2 (en) 2005-12-22 2007-08-14 Prime Source Building Products, Inc. Dual threaded screw for composite materials
DE102012215645B4 (en) * 2012-06-15 2016-08-18 Reisser Schraubentechnik Gmbh Screw and its use
JP2019002564A (en) * 2017-06-15 2019-01-10 エス・エフ・エス・インテク・ホルディング・アクチエンゲゼルシヤフト Screw having multiple-thread neck lower screw part
JP2019078153A (en) * 2017-10-25 2019-05-23 ヒロテツ工業株式会社 Drill screw for folded-plate roof and folded-plate roof method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1277044A (en) * 1968-09-09 1972-06-07 Illinois Tool Works Screw-type fasteners
GB2169051A (en) * 1984-12-21 1986-07-02 Sfs Stadler Ag Screws for fastening roof or wall liners

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1277044A (en) * 1968-09-09 1972-06-07 Illinois Tool Works Screw-type fasteners
GB2169051A (en) * 1984-12-21 1986-07-02 Sfs Stadler Ag Screws for fastening roof or wall liners

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996022472A1 (en) * 1995-01-18 1996-07-25 Grk Canada Ltd. A screw
US5919020A (en) * 1995-01-18 1999-07-06 Walther; Uli Screw
EP0849474A1 (en) * 1996-12-17 1998-06-24 MiTek Industries GmbH Drill screw
WO1999015796A1 (en) * 1997-09-22 1999-04-01 Sfs Industrie Holding Ag Screw for fixing wooden laths on a roof substructure or a wall foundation
US6325583B1 (en) 1997-09-22 2001-12-04 Sfs Industrie Holding Ag Screw for fixing wooden laths on a roof substructure or a wall foundation
DE29805784U1 (en) * 1998-03-30 1999-08-05 Sfs Ind Holding Ag Screw for fastening wooden slats to a roof or wall substructure
DE20003705U1 (en) * 2000-02-29 2001-07-12 Sfs Ind Holding Ag Heerbrugg Connection of two wooden beams that adjoin one another at least approximately at right angles
GB2397105B (en) * 2003-01-07 2005-03-02 Altenloh Brinck & Co Self-tapping screw for composite materials
GB2397105A (en) * 2003-01-07 2004-07-14 Altenloh Brinck & Co Self tapping screw having two threads of differing pitch
GB2428761A (en) * 2005-08-01 2007-02-07 Michael Wilkinson Screw
GB2428761B (en) * 2005-08-01 2008-04-09 Michael Wilkinson Universal screw
US7255523B2 (en) 2005-12-22 2007-08-14 Prime Source Building Products, Inc. Dual threaded screw for composite materials
DE102012215645B4 (en) * 2012-06-15 2016-08-18 Reisser Schraubentechnik Gmbh Screw and its use
DE102012215645C5 (en) 2012-06-15 2021-10-28 Reisser Schraubentechnik Gmbh Screw and its uses
JP2019002564A (en) * 2017-06-15 2019-01-10 エス・エフ・エス・インテク・ホルディング・アクチエンゲゼルシヤフト Screw having multiple-thread neck lower screw part
JP2019078153A (en) * 2017-10-25 2019-05-23 ヒロテツ工業株式会社 Drill screw for folded-plate roof and folded-plate roof method

Also Published As

Publication number Publication date
GB9122612D0 (en) 1991-12-04
AU8684191A (en) 1992-05-07
AU649736B2 (en) 1994-06-02

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