WO1984002380A1 - A screw - Google Patents

A screw Download PDF

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Publication number
WO1984002380A1
WO1984002380A1 PCT/GB1983/000304 GB8300304W WO8402380A1 WO 1984002380 A1 WO1984002380 A1 WO 1984002380A1 GB 8300304 W GB8300304 W GB 8300304W WO 8402380 A1 WO8402380 A1 WO 8402380A1
Authority
WO
WIPO (PCT)
Prior art keywords
screw
thread
further characterised
head
threaded
Prior art date
Application number
PCT/GB1983/000304
Other languages
French (fr)
Inventor
James Lawrence Seymour
George Edward Hardwick
Original Assignee
Gkn Screws Fasteners Ltd
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 Gkn Screws Fasteners Ltd filed Critical Gkn Screws Fasteners Ltd
Priority to BR8307720A priority Critical patent/BR8307720A/en
Priority to AU23355/84A priority patent/AU2335584A/en
Publication of WO1984002380A1 publication Critical patent/WO1984002380A1/en
Priority to DK394584A priority patent/DK394584D0/en

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16BDEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B35/00Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16BDEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/001Screws 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
    • F16B25/0015Screws 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 material being a soft organic material, e.g. wood or plastic
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16BDEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/0036Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
    • F16B25/0042Screws 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
    • F16B25/0047Screws 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 ridge being characterised by its cross-section in the plane of the shaft axis

Definitions

  • This invention relates to a screw for use in wood, particle board, plastics or in metal.
  • screw point and screw thread configuration are of course well known in the art.
  • GB-A-1357720 It is also known from GB-A-1357720 to provide a self- tapping screw having a single or multi-start helical thread wherein the included angle of the thread profile at its crest is 40° but wherein the axis of symmetry of the thread profile is inclined towards the screw head by at least 5° from the perpendicular to the screw axis.
  • Such a type of self-tapping screw is also known to be used in chipboard and is provided with a helix angle of between 10° and 12°.
  • GB-A-1564904 Furthermore it is known from GB-A-1564904 to provide a selfr-tapping screw having a thread helix angle of between 17° and 19° and an included angle of the thread profile at its crest of between 45° and 55°. Although such a screw is said to be usable in both metal and plastics materials, it is not said to be usable as a wood screw and the specification of GB-A-1564904 teaches that the above limits on helix and thread crest angles are critical.
  • a scant shank wood screw is described in GB-A-2072781 but this specification is especially concerned with the provision of an enlarged location collar immediately under the head of the screw.
  • a hardened steel screw having a head at one end, an entry portion at the other end and a threaded shank portion extending from the entry portion towards the head characterised in that the thread profile is of helical form wherein the helix angle is 20 or more, the included angle of the thread profile at its crest is 40° or less and the thread profile is symmetrical about an axis perpendicular to the longitudinal axis of the screw.
  • the said helix angle of the thread conveniently lies between 20° and 25° and the said included angle conveniently lies between 30° and 40°.
  • the said helix angle is substantially equal to 20° and the said included angle is substantially equal to 40°.
  • the threaded shank portion may extend from the entry portion to a position closely adjacent the underside of the head or may terminate short of the head to provide an unthreaded shank portion of a smaller diameter than the thread crest diameter of the threaded portion dependent upon the overall length of the screw and the type of screw required.
  • the thread preferably comprises a two start thread and is preferably raised rapidly to the full crest diameter from the entry portion of the screw.
  • the entry portion of the screw may comprise a tapered point or may be a blunt end and the threaded portion may extend to a position adjacent the end of the entry portion.
  • a tapered entry portion may comprise a conical unthreaded point wherein the included angle of the unthreaded point is substantially equal to 30°.
  • the diameter of the shank at the base of the thread conveniently lies within the range of 60% to 70% of the crest diameter of the thread.
  • a raised unthreaded location portion, or collar, may be provided immediately below the screw head having a diameter substantially equal to the crest diameter of the thread.
  • FIGURE 1 is a side elevation of a countersunk screw in accordance with the invention, the head being provided with a driving recess;
  • FIGURE 2 is a side elevation of the head and unthreaded shank portion of a countersunk screw similar to that shown in Figure 1 but having a cross slot in the head.
  • FIGURE 3 is an enlarged cross-sectional detail of the thread profile; and FIGURE 4 is a graph showing the relationship between torsional strength and nominal screw diameter (screw gauge) for hardened and non-hardened screws.
  • the screw shown in the drawing is manufactured from a cylindrical metal blank, usually of a low carbon steel, which is itself cropped to length from wire stock and then cold headed.
  • the screw comprises an un-threaded shank portion 10 corresponding to the diameter of the headed blank adjacent to which a rolled threaded portion 12 extends towards the entry portion 14 of the screw.
  • a head 16 shown herein as a counter-sunk head and having either a driving recess ( Figure 1) or a cross-slot ( Figure 2) therein for driving engagement by a driving tool.
  • the threaded portion 12 may extend substantially up to the underside of the head 16 from the entry portion 14.
  • the entry portion 14 of the screw comprises an unthreaded conical point having an included angle substantially equal to 30° from which a rapidly raised two start helical thread extends over the threaded .portion 12 to the un-threaded portion 10 of the shank.
  • the thread profile Is provided with steeply inclined flanks 20 to define therebetween an included angle to the thread profile at its crest which is substantially equal to 40° with the edge of the thread at the crest having a maximum thickness of 0.008 inches.
  • the helix angle of the helical thread in this example, is substantially equal to 20o and the thread profile is symmetrical about an axis perpendicular to the longitudinal axis of the screw.
  • the helix angle of the thread is always 20° or greater but preferably lies within the range 20° to 25° whilst the included angle of the thread profile at its crest is always 40° or less and preferably within the range 30° to 40°. It is found that, in use, the provision of a low included angle to the crest in combination with the high helix angle of the thread greatly facilitates the insertion of the screw by reducing the insertion torque which has to be applied. Comparative tests have been carried out on 2 inch screws of Number 10 Screw Gauge driven into beech wood to a depth of 30.5mm using a pilot hole in the wood of 3.2mm diameter. All the screws used in the tests were bright zinc plated and case hardened and were not provided with any low friction coating.
  • a screw may be produced in accordance with the invention by conventional cold heading and thread rolling techniques and it will be appreciated that the screw may have a cross slot or recess in its head and that such head may be of any suitable form.
  • the screw in accordance with the present invention is preferably provided with a two start thread which thread may extend from the unthreaded shank portion 10 either to the end or to the start of the entry portion 14.
  • a two start thread which thread may extend from the unthreaded shank portion 10 either to the end or to the start of the entry portion 14.
  • entry portion comprising a conical unthreaded point
  • such entry portion may be threaded to the end thereof and may either taper to a point or may comprise a relatively blunt end.
  • the screw need not be provided with the unthreaded shank portion 10, whereby the threaded portion 12 may extend from the entry portion 14 substantially up to the underside of the head 16.
  • a raised unthreaded location portion in the form of a cylindrical or frusto-conical collar may be provided immediately below the screw head 16, such collar having a maximum diameter substantially equal to the crest diameter of the threaded portion 12.
  • the diameter of the shank at the base of the thread preferably lies within the range of 60% to 70% of the crest diameter of the thread dependant upon the Screw Gauge number as follows :-
  • Screws produced in accordance with the invention are always hardened, either case hardened or through hardened, in order to give them sufficient torsional strength for use in their various applications i.e. in both hard and soft woods, man-made board materials, plastics or metals. It is of course conventional practice to harden self-tapping screws but wood screws are not usually hardened and reference may be had to Figure 4 which shows the relationship between torsional strength and nominal screw diameter (i.e. screw gauge number) for hardened and nonhardened screws.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Geometry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Dispersion Chemistry (AREA)
  • Wood Science & Technology (AREA)
  • Connection Of Plates (AREA)
  • Joining Of Building Structures In Genera (AREA)
  • Materials For Medical Uses (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
  • Transmission Devices (AREA)

Abstract

A screw usable as either a wood screw or a self-tapping screw comprises a two start helical thread (12) having a helix angle of 20o or more with an included angle to the thread profile at its crest of 40o or less. The threads are raised rapidly from a conical un-threaded entry point (14) and the thread crest diameter is greater than that of the unthreaded shank portion (10) of the screw.

Description

A Screw
This invention relates to a screw for use in wood, particle board, plastics or in metal.
Many different designs of screw point and screw thread configuration are of course well known in the art. In particular, it is known to provide a wood screw wherein the helix angle of the thread is between 14° and 16° and wherein the included angle of the thread profile at its crest is 50°. It is known to provide such a screw with a double thread to give a twin start facilitating its initial insertion into wood.
It is also known from GB-A-1357720 to provide a self- tapping screw having a single or multi-start helical thread wherein the included angle of the thread profile at its crest is 40° but wherein the axis of symmetry of the thread profile is inclined towards the screw head by at least 5° from the perpendicular to the screw axis. Such a type of self-tapping screw is also known to be used in chipboard and is provided with a helix angle of between 10° and 12°.
Furthermore it is known from GB-A-1564904 to provide a selfr-tapping screw having a thread helix angle of between 17° and 19° and an included angle of the thread profile at its crest of between 45° and 55°. Although such a screw is said to be usable in both metal and plastics materials, it is not said to be usable as a wood screw and the specification of GB-A-1564904 teaches that the above limits on helix and thread crest angles are critical.
The traditional methods of manufacturing screws by cutting threads have been largely replaced by current production methods involving rolling a thread onto the shank of a headed cylindrical metal blank. Such a rolling operation produces a thread crest diameter greater than the diameter of the original blank so that, in order to achieve a particular thread crest diameter, one starts with a smaller blank diameter. This leaves any un-threaded portion of the shank with a smaller diameter than the thread crest diameter and such screws are known in the art as scant shank screws.
A scant shank wood screw is described in GB-A-2072781 but this specification is especially concerned with the provision of an enlarged location collar immediately under the head of the screw.
It is an object of the present invention to provide an improved screw which, by virtue of its particular thread form, will be capable of advantageous application as a wood screw for use in woods or plastics or as a self-tapping screw for use in metals.
In accordance with the invention there is provided a hardened steel screw having a head at one end, an entry portion at the other end and a threaded shank portion extending from the entry portion towards the head characterised in that the thread profile is of helical form wherein the helix angle is 20 or more, the included angle of the thread profile at its crest is 40° or less and the thread profile is symmetrical about an axis perpendicular to the longitudinal axis of the screw.
The said helix angle of the thread conveniently lies between 20° and 25° and the said included angle conveniently lies between 30° and 40°. Preferably the said helix angle is substantially equal to 20° and the said included angle is substantially equal to 40°.
The threaded shank portion may extend from the entry portion to a position closely adjacent the underside of the head or may terminate short of the head to provide an unthreaded shank portion of a smaller diameter than the thread crest diameter of the threaded portion dependent upon the overall length of the screw and the type of screw required.
The thread preferably comprises a two start thread and is preferably raised rapidly to the full crest diameter from the entry portion of the screw. The entry portion of the screw may comprise a tapered point or may be a blunt end and the threaded portion may extend to a position adjacent the end of the entry portion. A tapered entry portion may comprise a conical unthreaded point wherein the included angle of the unthreaded point is substantially equal to 30°.
The diameter of the shank at the base of the thread conveniently lies within the range of 60% to 70% of the crest diameter of the thread.
A raised unthreaded location portion, or collar, may be provided immediately below the screw head having a diameter substantially equal to the crest diameter of the thread.
Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings wherein:
FIGURE 1 is a side elevation of a countersunk screw in accordance with the invention, the head being provided with a driving recess;
FIGURE 2 is a side elevation of the head and unthreaded shank portion of a countersunk screw similar to that shown in Figure 1 but having a cross slot in the head.
FIGURE 3 is an enlarged cross-sectional detail of the thread profile; and FIGURE 4 is a graph showing the relationship between torsional strength and nominal screw diameter (screw gauge) for hardened and non-hardened screws.
The screw shown in the drawing is manufactured from a cylindrical metal blank, usually of a low carbon steel, which is itself cropped to length from wire stock and then cold headed. The screw comprises an un-threaded shank portion 10 corresponding to the diameter of the headed blank adjacent to which a rolled threaded portion 12 extends towards the entry portion 14 of the screw. At the other end of the screw there is provided a head 16, shown herein as a counter-sunk head and having either a driving recess (Figure 1) or a cross-slot (Figure 2) therein for driving engagement by a driving tool. It will be appreciated that, dependant upon length and application requirement, the threaded portion 12 may extend substantially up to the underside of the head 16 from the entry portion 14.
The entry portion 14 of the screw comprises an unthreaded conical point having an included angle substantially equal to 30° from which a rapidly raised two start helical thread extends over the threaded .portion 12 to the un-threaded portion 10 of the shank. In this example the thread profile Is provided with steeply inclined flanks 20 to define therebetween an included angle to the thread profile at its crest which is substantially equal to 40° with the edge of the thread at the crest having a maximum thickness of 0.008 inches. The helix angle of the helical thread, in this example, is substantially equal to 20º and the thread profile is symmetrical about an axis perpendicular to the longitudinal axis of the screw. In accordance with the invention the helix angle of the thread is always 20° or greater but preferably lies within the range 20° to 25° whilst the included angle of the thread profile at its crest is always 40° or less and preferably within the range 30° to 40°. It is found that, in use, the provision of a low included angle to the crest in combination with the high helix angle of the thread greatly facilitates the insertion of the screw by reducing the insertion torque which has to be applied. Comparative tests have been carried out on 2 inch screws of Number 10 Screw Gauge driven into beech wood to a depth of 30.5mm using a pilot hole in the wood of 3.2mm diameter. All the screws used in the tests were bright zinc plated and case hardened and were not provided with any low friction coating. The results of the tests are tabulated below which show that the screw according to the invention, which was provided with a two start thread having a 20° helix angle and 40° included crest angle, resulted in a substantially lower insertion torque than that required to drive the known forms of screw :-
Conventional Conventional Conventional Screw of Wood Screw Self-Tapping Two Start the Invention to BS1210 Screw to Wood Screw BS4174
Newton Newton Newton Newton Metres Metres Metres Metres insertion insertion insertion insertion torque torque torque torque
5.1 - 5.5 4.6 - 4.7 5.3 - 5.5 3.5 -4.0 Tests have also been carried out on the insertion speed of the screws described above as measured by the number of turns required to fully apply the screw, i.e. to bury the countersunk head in the wood :-
No. 10 Screw Gauge 2" Screw
Conventional Conventional Conventional Screw of the Wood Screw Self-Tapping Two Start Invention to BS1210 Screw to Wood Screw BS4174
26 turns 32 turns 15 turns 11.1 turns
No. 12 Screw Gauge 3" Screw
Conventional Conventional Conventional Screw of the Wood Screw Self-Tapping Two Start Invention to BS1210 Screw to Wood Screw BS4174
33 turns 42 turns 19.5 turns 14.3 turns
A screw may be produced in accordance with the invention by conventional cold heading and thread rolling techniques and it will be appreciated that the screw may have a cross slot or recess in its head and that such head may be of any suitable form. The screw in accordance with the present invention is preferably provided with a two start thread which thread may extend from the unthreaded shank portion 10 either to the end or to the start of the entry portion 14. Thus, although the specific example described hereinbefore is provided with an entry portion comprising a conical unthreaded point, such entry portion may be threaded to the end thereof and may either taper to a point or may comprise a relatively blunt end. As mentioned hereinbefore, the screw need not be provided with the unthreaded shank portion 10, whereby the threaded portion 12 may extend from the entry portion 14 substantially up to the underside of the head 16. Also, a raised unthreaded location portion in the form of a cylindrical or frusto-conical collar may be provided immediately below the screw head 16, such collar having a maximum diameter substantially equal to the crest diameter of the threaded portion 12.
In the screw of the present invention the diameter of the shank at the base of the thread preferably lies within the range of 60% to 70% of the crest diameter of the thread dependant upon the Screw Gauge number as follows :-
Thread Base/Thread Screw Gauge Number Crest Diameter
3 64% 4 62% 5 62% 6 68% 7 68% 8 68%
9 63% 10 63% 12 63% 14 63% Screws produced in accordance with the invention are always hardened, either case hardened or through hardened, in order to give them sufficient torsional strength for use in their various applications i.e. in both hard and soft woods, man-made board materials, plastics or metals. It is of course conventional practice to harden self-tapping screws but wood screws are not usually hardened and reference may be had to Figure 4 which shows the relationship between torsional strength and nominal screw diameter (i.e. screw gauge number) for hardened and nonhardened screws.

Claims

1. A hardened steel screw having a head (16) at one end, an entry portion (14) at the other end. and a threaded shank portion (12) extending from the entry portion towards the head, characterised in that the thread profile is of helical form wherein the helix angle is 20° or more, the included angle of the thread profile at its crest is 40° or less and the thread profile is symmetrical about an axis perpendicular to the longitudinal axis of the screw.
2. A screw as claimed in Claim 1 further characterised in that the said helix angle of the thread is between 20° and 25° and the said included angle is between 30° and 40°.
3. A screw as claimed in Claim 2 further characterised in that the said helix angle is substantially equal to 20° and the said included angle is substantially equal to 40°.
4. A screw as claimed in any one of the preceding Claims further characterised in that the thread comprises a two start thread.
5. A screw as claimed in any one of the preceding Claims further characterised in that the threaded shank portion (12) thereof extends to the end of the entry portion (14).
6. A screw as claimed in any one of Claims 1 to 4 further characterised in that the threaded shank portion (12) thereof extends to the start of the entry portion (14).
7. A screw as claimed in any one of the preceding Claims further characterised in that the entry portion (14) is tapered.
8. A screw as claimed in Claim 7 further characterised in that the thread is raised rapidly from the tapered entry portion (14) to the full thread crest diameter.
9. A screw as claimed in Claim 8 further characterised in that the tapered entry portion (14) comprises a conical unthreaded point.
10. A screw as claimed in Claim 9 further characterised in that the included angle of the conical un-threaded point is substantially equal to 30°.
11. A screw as claimed in any one of the preceding claims further characterised in that an unthreaded shank portion (10) is provided between the threaded portion (12) and the head (16), the diameter of the portion (10) being less than the crest diameter of the threaded portion (12).
12. A screw as claimed in any one of Claims 1 to 10 further characterised in that the threaded portion (12) extends from the entry portion (14) substantially up to the underside of the head (16).
13. A screw as claimed in any one of the preceding claims further characterised in that a raised unthreaded location portion is provided immediately below the head (16), said portion having a maximum diameter substantially equal to the crest diameter of the threaded portion (12).
PCT/GB1983/000304 1982-12-17 1983-11-28 A screw WO1984002380A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR8307720A BR8307720A (en) 1982-12-17 1983-11-28 HARDENED STEEL SCREW
AU23355/84A AU2335584A (en) 1982-12-17 1983-11-28 A screw
DK394584A DK394584D0 (en) 1982-12-17 1984-08-16 SCREW

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8236024 1982-12-17

Publications (1)

Publication Number Publication Date
WO1984002380A1 true WO1984002380A1 (en) 1984-06-21

Family

ID=10535066

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1983/000304 WO1984002380A1 (en) 1982-12-17 1983-11-28 A screw

Country Status (11)

Country Link
EP (1) EP0161250A1 (en)
KR (1) KR840007454A (en)
ES (1) ES285333Y (en)
GB (1) GB2131907B (en)
HK (1) HK77787A (en)
IT (2) IT8368312A0 (en)
NO (1) NO842746L (en)
NZ (1) NZ206599A (en)
SG (1) SG51387G (en)
WO (1) WO1984002380A1 (en)
ZA (1) ZA839333B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT389923B (en) * 1988-01-29 1990-02-26 Sfs Stadler Ag SELF-DRILLING AND THREADING SCREW FOR TURNING INTO GAS-CONCRETE
AU2010200536A1 (en) * 2010-02-12 2011-09-01 Illinois Tool Works Inc. Self-drilling screw

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8912483D0 (en) * 1989-05-31 1989-07-19 Unifix Ltd A fastening device
US5244327A (en) * 1992-04-29 1993-09-14 Whitesell Neil L Trailer bed fastener
GB2325288A (en) * 1997-05-14 1998-11-18 Europ Ind Services Limited Threaded fastener, and method and rolling dies for making it
US6702537B2 (en) * 2001-01-12 2004-03-09 Illinois Tool Works Inc. High profile thread forming screw
DE10228505A1 (en) * 2002-06-20 2004-01-08 Swg Schraubenwerk Gaisbach Gmbh Wood screw and method for its manufacture
ITTV20120113A1 (en) * 2012-06-12 2013-12-13 Scarpa Calzaturificio Spa SKI BOOT

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1440812A (en) * 1965-04-22 1966-06-03 Visserie Boulonnerie Japy Soc Screws in particular for panels made of reconstituted material
FR2176351A5 (en) * 1972-03-15 1973-10-26 Knipping Srl
DE3003280A1 (en) * 1980-01-30 1981-08-06 Frank 5758 Fröndenberg Knoche Enhanced grip self tapping screw - has twin threads with same pitch and different thread thickness
FR2526498A1 (en) * 1982-05-10 1983-11-10 Canalisations Ste Gle Pipe clip for friable materials - has archimedean-screwed shank for rapid fixing of base with resilient jaws

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2350346A (en) * 1943-04-14 1944-06-06 Clifford R Gaskell Self-tapping screw
GB1233175A (en) * 1967-07-10 1971-05-26
US3937119A (en) * 1974-12-23 1976-02-10 Illinois Tool Works, Inc. Masonry anchor device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1440812A (en) * 1965-04-22 1966-06-03 Visserie Boulonnerie Japy Soc Screws in particular for panels made of reconstituted material
FR2176351A5 (en) * 1972-03-15 1973-10-26 Knipping Srl
DE3003280A1 (en) * 1980-01-30 1981-08-06 Frank 5758 Fröndenberg Knoche Enhanced grip self tapping screw - has twin threads with same pitch and different thread thickness
FR2526498A1 (en) * 1982-05-10 1983-11-10 Canalisations Ste Gle Pipe clip for friable materials - has archimedean-screwed shank for rapid fixing of base with resilient jaws

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT389923B (en) * 1988-01-29 1990-02-26 Sfs Stadler Ag SELF-DRILLING AND THREADING SCREW FOR TURNING INTO GAS-CONCRETE
AU2010200536A1 (en) * 2010-02-12 2011-09-01 Illinois Tool Works Inc. Self-drilling screw

Also Published As

Publication number Publication date
KR840007454A (en) 1984-12-07
GB2131907A (en) 1984-06-27
NZ206599A (en) 1985-08-16
GB2131907B (en) 1986-10-29
GB8331727D0 (en) 1984-01-04
ES285333U (en) 1985-09-01
HK77787A (en) 1987-10-30
ZA839333B (en) 1984-08-29
NO842746L (en) 1984-07-05
ES285333Y (en) 1989-08-01
IT8354049V0 (en) 1983-12-16
EP0161250A1 (en) 1985-11-21
IT8368312A0 (en) 1983-12-16
SG51387G (en) 1987-08-28

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