EP3775584A1 - Self-tapping screw for concrete - Google Patents
Self-tapping screw for concreteInfo
- Publication number
- EP3775584A1 EP3775584A1 EP19708764.6A EP19708764A EP3775584A1 EP 3775584 A1 EP3775584 A1 EP 3775584A1 EP 19708764 A EP19708764 A EP 19708764A EP 3775584 A1 EP3775584 A1 EP 3775584A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- screw
- thread
- axis
- extremity
- angle
- 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- Withdrawn
Links
- 239000004567 concrete Substances 0.000 title claims abstract description 23
- 238000010079 rubber tapping Methods 0.000 title claims abstract description 12
- 238000005096 rolling process Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000005553 drilling Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
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
- F16B25/001—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
- F16B25/0026—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 material being a hard non-organic material, e.g. stone, concrete or drywall
-
- 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
- F16B25/0047—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 ridge being characterised by its cross-section in the plane of the shaft axis
-
- 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
-
- 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
- F16B25/0078—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw with a shaft of non-circular cross-section or other special geometric features of the shaft
-
- 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
- F16B25/0084—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 geometric details of the tip
Definitions
- the invention relates to a self-tapping screw for concrete.
- a self-tapping screw for concrete is a fastening component which is screwed into a pre-drilled hole in concrete.
- the hole is drilled with a predetermined diameter, and the screw is configured to form a tapping in the peripheral wall of the hole as it is being screwed in.
- the invention thus proposes a self-tapping screw for concrete comprising a threaded rod, of which one extremity is free and an opposite extremity is connected to a head for driving the screw causing it to rotate about its axis by means of an appropriate tool, the threaded rod comprising a core having a diameter D1 and at least one thread which extends in a helix around the core and has an external diameter D2, said at least one thread having a generally triangular or trapezoidal form in cross section in a plane passing through said axis, comprising:
- said radius R is equal to K x (D2-D1 )/2, where K lies between 1 and 1 .5.
- the thread thus has an asymmetrical form with parameters D2/D1 , a and R which are optimized in order to impart a good performance to the screw.
- the advantages of this screw are numerous and include in particular:
- the screw according to the invention may comprise one or a plurality of the following characterizing features, taken in isolation one from the other or in combination one with the other:
- said angle a lies between 4 and 8°, and is preferably 6°
- the screw comprises a single thread
- the thread exhibits a pitch P between 0.9 x D1 and 1 .1 x D1 , and preferably between 0.95 x D1 and 1 .05 x D1 ,
- the thread has the same profile for substantially its entire length and is devoid of lead teeth at its extremity situated on the side of said free extremity
- the screw comprises at least one longitudinal flute which extends through said at least one thread and into said core, from said free extremity,
- said at least one flute has a length of more than 2 x D1 ,
- said at least one flute has the general form of a dihedron in cross section, in a plane perpendicular to said axis,
- said dihedron has an angle g between 60 and 120°, preferably between 80 and 100°, and more preferably in the order of 90°,
- said dihedron comprises a first wall extending substantially in a median longitudinal plane of said screw
- said dihedron comprises a second wall, of which a plane first portion is substantially parallel to said axis and extends from said free extremity, and of which a second portion curved inwards in a concave manner extends between the first portion and the external periphery of the threaded rod,
- said second portion has a radius F between 3 x D1 and 6 x D1 , and preferably between 4 x D1 and 5 x D1 , and
- the screw comprises a single flute.
- FIG. 1 to 3 represent a self-tapping screw for concrete according to the prior art, figures 2 and 3 being detailed views on a larger scale, - figure 4 is a schematic view in perspective of a self-tapping screw according to the invention,
- figure 7 is a schematic view from above of the screw in figure 4,
- figure 8 is a schematic view from below of the screw in figure 4,
- figure 9 is a view on a larger scale of the ringed detail in figure 6, and
- Figures 1 to 3 represent a self-tapping screw 10 for concrete according to the prior art.
- the screw 10 is designed to be screwed into a pre-drilled hole in concrete.
- the screw 10 comprises essentially two parts, these being a threaded rod 12 and a head 14 for driving the screw causing it to rotate about its axis A.
- the rod 12 includes a core 16 having a diameter D1 and a thread 18 which extends in a helix around the core 16 and has an external diameter D2.
- the thread has in cross section, in a plane passing through the axis A, a generally triangular form, of which the point forms an angle b (figure 2).
- the thread 18 comprises a flank 18a situated to the side of the free extremity of the rod 12, which forms an angle a with the aforementioned plane (figure 2).
- the opposite flank 18b of the thread 18 exhibits a radius of curvature R (figure 3).
- the relationship D2/D1 is more than or equal to 1.5, the angle a is more than 10°, and the angle b is more than or equal to 60°.
- the radius R is equal to K x (D2-D1 )/2, where K is in the order of 2.
- Figures 4 to 8 represent a self-tapping screw 1 10 for concrete according to the invention.
- the screw 1 10 is designed to be screwed into a pre-drilled hole in concrete.
- the screw 1 10 comprises a threaded rod 1 12, of which one extremity is free and an opposite extremity is connected to a head 1 14 for driving the screw causing it to rotate about its longitudinal A axis by means of an appropriate tool.
- the head in this case has a generally polygonal form, for example of type SW10, although this is in no way restrictive.
- the rod 1 12 includes a core 1 16 having a diameter D1 and at least one thread 118 which extends in a helix around the core 1 16 and has an external diameter D2.
- the thread has a generally triangular or trapezoidal form in cross section, in a plane passing through the axis A (figure 9).
- This triangular or trapezoidal form includes:
- D2/D1 is less than 1.5; and it preferably lies between 1 .3 and 1.4; - the angle a lies between 0 and 10°; it preferably lies between 4 and 8°, and more preferably it is 6°; and
- the screw 1 10 according to the invention comprises one or a plurality of the following optimized parameters:
- the angle b is measured between the lateral flanks, at the top of the point (that is to say at the radially external free extremity of the point), and is less than 60°; it is preferably more than 45°,
- the thread exhibits a pitch P between 0.9 x D1 and 1 .1 x D1 , and preferably between 0.95 x D1 and 1 .05 x D1 ,
- the point 120 exhibits a thickness e between 0.1 and 0.3 mm, and for example in the order of 0.2 mm.
- the screw 1 10 preferably comprises a single thread 1 18, which simplifies its design.
- the thread may have the same profile for substantially its entire length and is devoid of lead teeth at its extremity situated on the side of the free extremity.
- the screw in this case is relatively simple to produce, for example by stamping and rolling, these being methods that are well known to a person skilled in the art.
- the screw 1 10 thus comprises an asymmetrical thread 1 18.
- a symmetrical thread with an angle at the tip b necessarily causes stresses that are more axial than those caused by the asymmetrical thread with the same angle b. It is possible to describe the angle (b - a), which orients the stresses in a more or less radial manner.
- the radius R of the asymmetrical thread in relation to the equivalent straight thread with the same angle b reduces the interference with the concrete, which is represented schematically by the hatched area in figure 10.
- the lines T1 , T2 in figure 11 show the diameters of drills that are respectively worn, that is to say having a reduced diameter, and new, that is to say having a maximum diameter.
- the dissymmetry of the thread, with respect to the equivalent symmetrical straight thread reduces the interference with the concrete; this difference is even more important in the case of a hole drilled with a worn drill of which the external diameter would be less than D2.
- the screw may comprise inter alia a cylindrical collar 127 for connecting the threaded rod 1 12 to the head 1 14.
- the diameter D’ of this collar is preferably smaller than the diameter of the hole into which the screw 1 10 must be screwed.
- the length of the collar depends in particular on the total length of the screw. D’ is more than D1 and may be less than D2.
- This collar corresponds in general to the diameter of the cylindrical rod of the blank obtained after stamping and before rolling.
- the free extremity of the threaded rod 1 12 may be configured as a frustum of a cone and may comprise an end face perpendicular to the axis A, of which the diameter lies between 0.75 x D1 and 0.9 x D1.
- This frustum of a cone has a length between 0.2 x D1 and 0.3 x D1.
- the screw 1 10 may in addition comprise at least one longitudinal flute 128, preferably a single flute, which extends through the thread 1 18 and into the core 1 16 from the free extremity of the threaded rod.
- This flute 128 is particularly useful in situations where the concrete into which the screw is to be screwed is reinforced and contains reinforcing bars. The flute 128 would then make it easier to address these bars.
- the flute 128 is produced by machining, for example, after the rolling operation.
- This flute may comprise one or a plurality of the following characterizing features and/or optimized parameters:
- the flute 128 has a length of more than 2 x D1 ,
- the flute 128 has the general form of a dihedron 130 in cross section, in a plane perpendicular to the axis A (figure 8), - the dihedron 130 has an angle g between 60 and 120°, preferably between 80 and 100°, and more preferably in the order of 90°,
- the dihedron 130 comprises a first wall 130a extending substantially in a median longitudinal plane of said screw
- the dihedron 130 comprises a second wall 130b, of which a first portion 130ba plane is substantially parallel to the axis A and extends from the free extremity of the threaded rod, and a second portion 130bb is curved inwards in a concave manner and extends between the first portion and the external periphery of the threaded rod,
- the first portion has a length L1 between 2 x D1 and 2.5 x D1 ,
- the second portion has a radius F between 3 x D1 and 6 x D1 , and preferably between
- the flute 128 is situated at a radial distance L2 from the axis 1 , which is between 0.3 x D1 and 0.5 x D1.
- the drilling diameter of the hole in the concrete depends on the diameter of the screw.
- the diameters D1 and D2 could be in the order of 5.7 mm and 7.74 mm respectively.
- the pitch P could be 5.6 mm.
- the rod 1 12 would then have a length between 35 and 55 mm.
- the screw 1 10 is made of tempered steel, for example.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Joining Of Building Structures In Genera (AREA)
- Dowels (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1852987A FR3079891B1 (en) | 2018-04-06 | 2018-04-06 | CONCRETE SELF-TAPPING SCREW |
PCT/US2019/020312 WO2019194920A1 (en) | 2018-04-06 | 2019-03-01 | Self-tapping screw for concrete |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3775584A1 true EP3775584A1 (en) | 2021-02-17 |
Family
ID=62816744
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19708764.6A Withdrawn EP3775584A1 (en) | 2018-04-06 | 2019-03-01 | Self-tapping screw for concrete |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3775584A1 (en) |
FR (1) | FR3079891B1 (en) |
WO (1) | WO2019194920A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102021211692A1 (en) * | 2021-10-15 | 2023-04-20 | Toge Dübel Gmbh & Co. Kg | Self tapping screw |
Family Cites Families (6)
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 |
EP0625400A1 (en) * | 1993-05-04 | 1994-11-23 | LUDWIG HETTICH SCHRAUBENFABRIK GmbH & Co. | Tool for the formation of an internal thread |
WO2001001000A1 (en) * | 1999-06-28 | 2001-01-04 | Aoyama Seisakusho Co., Ltd. | Tapping screw |
DE102010028824A1 (en) * | 2010-05-10 | 2011-11-10 | Hilti Aktiengesellschaft | Thread cutting concrete screw |
DE102013108743A1 (en) * | 2013-08-13 | 2015-02-19 | Fischerwerke Gmbh & Co. Kg | concrete screw |
DE102014219116A1 (en) * | 2014-09-23 | 2016-03-24 | Toge Dübel Gmbh & Co. Kg | Self-tapping screw for screwing into a borehole in a material, arrangement with such a screw and method for screwing such a screw into a borehole |
-
2018
- 2018-04-06 FR FR1852987A patent/FR3079891B1/en not_active Expired - Fee Related
-
2019
- 2019-03-01 WO PCT/US2019/020312 patent/WO2019194920A1/en active Application Filing
- 2019-03-01 EP EP19708764.6A patent/EP3775584A1/en not_active Withdrawn
Also Published As
Publication number | Publication date |
---|---|
FR3079891A1 (en) | 2019-10-11 |
FR3079891B1 (en) | 2020-04-24 |
WO2019194920A1 (en) | 2019-10-10 |
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