DE202016107016U1 - Self-tapping screw for screwing into a dowel - Google Patents

Abstract

Self-tapping screw for screwing into a dowel with a cylindrical core (9) with a core diameter (D) and with a threaded portion (A) with a cutting thread (10) for screwing the screw (2) into a dowel Shell, wherein the cutting thread (10) has a thread diameter (D) where:

Description

The invention relates to a self-tapping screw for screwing into a dowel and a connection arrangement with such a concrete screw and a dowel.

Screws are used to attach objects, for example, to a wall or ceiling. It is known to screw a self-rotating screw into a borehole.

Generic concrete screws are from the DE 10 2014 222 891 A1 and DE 10 2014 219 116 A1 known.

The invention has for its object to provide a self-tapping screw, which can be screwed reliably independent of a surrounding a wellbore material into the wellbore.

This object is solved by the features of claims 1 and 10. The essence of the invention is that a self-tapping screw is designed such that it can be screwed into a dowel. The dowel is inserted into a borehole. With the screws known from the prior art, such an arrangement is not readily possible. The known concrete screws have high thread flanks, so there is a risk that when screwing the screw, the thread flanks cut the jacket of the anchor. It has been recognized that a self-tapping screw, in particular a self-tapping concrete screw, is designed such that a self-tapping cutting thread of the screw can cut into the dowel without destroying it.

The anchor can advantageously be done for anchoring, in particular with little support bidding surrounding material around the wellbore. In particular, the height of the thread flanks is smaller than the shell thickness of the anchor. It is possible to cut the thread into the dowel without cutting through the dowel casing. The thread diameter is larger than the core diameter. The result is a low stress of the material and a low requirement of the tool, so that the self-tapping screw according to the invention is versatile. The self-tapping screw is in particular a self-tapping concrete screw.

In a screw according to claim 2, the risk of destruction of the anchor is further reduced.

A screw according to claim 3 allows a simplified screwing, so screwing the screw into the dowel with reduced torque, since the relatively sharp thread flanks cause a reduced resistance force during screwing.

In a screw according to claim 4 ensures that despite the reduced thread diameter compared to a screw known from the prior art, a sufficient holding force is made possible. The cutting thread is narrower. This results in an improved self-locking effect. The thread pitch is a maximum of 1.5 times the core diameter. As a result, a non-destructive screwing the self-tapping screw is ensured in the dowel. In particular, can be dispensed with a Anschneid element of the cutting thread.

In a screw according to claim 5, the cutting of the cutting thread is facilitated in the dowel coat.

In a screw according to claim 6 fastening of an object is ensured on the screw. The fastening unit may in particular have a one-piece integrally formed screw head, in particular a countersunk head or a flat head. The fastening unit may alternatively also have a fastening thread, in particular a metric thread, in particular a metric outer thread, with a corresponding fastening element, in particular a fastening nut. The screw is particularly suitable as a fastener for the household.

In a screw according to claim 7 screwing the screw is ensured by means of a tool. The non-circular contour is in particular a non-circular inner contour or a non-circular outer contour. A non-circular contour can be polygonal, for example, and have, for example, a triangular, square, hexagonal or octagonal contour. Also possible is a multi-round contour, in particular a six-round contour.

In a screw according to claim 8 screwing the screw is ensured by means of a conventional tool. Special tools, especially a tangential impact driver, are unnecessary.

In a screw according to claim 9 screwing the screw is further improved in a dowel.

A connection arrangement according to claim 10 enables a universal use of the screw. In particular, a screwing of the screw is ensured in a dowel with a maximum torque of 14 Nm. In particular, it is possible to screw the self-tapping screw into the dowel, wherein the cutting thread cuts into the dowel shell without destroying the dowel. By cutting the cutting thread into the dowel, it is possible to drive the screw in the dowel. The screwing in of the screw is improved. In particular, destruction of the dowel is prevented even if the screw rests with the core on the inner cylinder surface of the dowel, so if the core diameter is greater than or equal to the dowel inner diameter.

In particular, the thread diameter is less than 0.9 times the plug outer diameter, in particular less than 0.7 times the plug outer diameter, in particular less than 0.5 times the plug outer diameter. This ensures that the cutting thread cuts into a dowel shell for propulsion in the dowel without destroying it.

In a connection arrangement according to claim 11, a universal use of the connection arrangement is ensured. Regardless of the material, it is easy to screw in the screw, especially with a maximum torque of 14 Nm.

In a connection arrangement according to claim 12 ensures that the screw does not protrude beyond the length of the dowel and thus the dowel is destroyed. Advantageously, the connection arrangement can have a borehole depth of the borehole which is determined such that the borehole can end behind a reinforcement layer embedded in the material. As a result, a collision-free screwing the screw is ensured. The length of the screw is not limited by the embedded reinforcing layer.

In a connection arrangement according to claim 13 screwing the screw is further facilitated in the dowel. Depending on the material, the dowel is designed as a plastic dowel, gypsum plasterboard dowels, insulating dowels, cavity dowels, metal expansion dowels, composite anchors, undercut anchors or screw anchors. A plastic dowel is made in particular of polyamide. A plastic dowel can be produced cost-effectively in large quantities.

In a connection arrangement according to claim 14, the hold of the dowel in the borehole is improved. The fastening element can be designed in particular as a thread, expansion element, deformation element, as a profile, in particular as a sawtooth profile or the like.

In a connection arrangement according to claim 15, the screwing of the concrete screw is further facilitated in the dowel.

In a connection arrangement according to claim 16, the maintenance of the concrete screw in the dowel is further improved.

In a connection arrangement according to claim 17 it is ensured that the dowel sheath thickness is selected such that the cutting thread cuts into the dowel sheath for propulsion into the dowel without destroying the dowel sheath. The risk of the cutting thread breaking the dowel sheath is further reduced if the dowel sheath thickness is greater than or equal to the flank height of the cutting thread.

• 1 eine Schnittdarstellung einer Verbindungsanordnung mit einer erfindungsgemäßen Schraube gemäß einem ersten Ausführungsbeispiel in einem Bohrloch vorgesehenen Dübel,
• 2 einen vergrößerten Ausschnitt des Details I der Verbindungsanordnung gemäß 1,
• 3 eine Draufsicht auf die Schraube gemäß 1 und
• 4 eine Seitenansicht einer Schraube gemäß einem zweiten Ausführungsbeispiel.

Further advantageous embodiments, additional features and details of the invention will become apparent from the following description of two embodiments with reference to the 1 to 4 , These show:

• 1 a sectional view of a connection arrangement with a screw according to the invention according to a first embodiment provided in a borehole dowels,
• 2 an enlarged detail of the detail I of the connection arrangement according to 1 .
• 3 a plan view of the screw according to 1 and
• 4 a side view of a screw according to a second embodiment.

At one in the 1 to 3 shown connection arrangement 1 is a self-tapping screw 2 in a borehole 3 in one in one material 4 located dowels 5 screwed. According to the embodiment shown, the material 4 Concrete. The screw 2 is a concrete screw. The concrete screw 2 is from the tool steel 20 MnB4 made. This tool steel has the material number 1.5525. It is advantageous if the concrete screw 2 is made of a boron-alloyed steel. In principle, boron-alloyed steel materials with slightly modified chemical compositions are also suitable, the carbon content being less than 0.15 to 0.20% by weight at 17 MnB4 (material number 1.5520) and 0.20 to 0.25% by weight at 23 MnB4 (material number 1.5535) may be greater than 20 MnB4, in which the carbon content is 0.18 to 0.23 wt .-%. The dowel 5 is a plastic dowel.

The borehole 3 is designed as a blind hole. The borehole 3 has a borehole depth T _B. The borehole depth T _B is greater than 30 mm according to the embodiment shown. The downhole depth T _B is greater than a reinforcement depth T _A. As reinforcement depth T _A is the distance of a reinforcing layer 6 from a surface 7 of the material 4 designated. The reinforcing layer 6 serves to reinforce the material 4 , In concrete is the reinforcing layer 6 as a steel reinforcement, in particular in the form of steel rods, in particular in the form of profiled steel rods, as designed with, for example, an external coarse thread. If the hole depth T _{B is} greater than the reinforcement depth T _A , is through the dowel 5 ensures that the concrete screw 2 not with the reinforcing layer 6 collided. The borehole 3 also has a borehole diameter D _B. According to the embodiment shown: D _B = 6 mm.

The dowel 5 and the concrete screw 2 have a common central longitudinal axis 8th on. The concrete screw 2 has a cylindrical core 9 with a core diameter D _K and a cutting thread 10 with a thread diameter D _G on. According to the embodiment shown: D _K = 5.5 mm and D _G = 7 mm. In particular: D _G ≈ 1.27 • D _K. It is advantageous if the thread diameter D _{G has} at most 1.4 times the core diameter D _K.

The cutting thread 10 has a thread pitch S. According to the embodiment shown: S = 4.4 mm. According to the embodiment shown: S = 0.8 • D _K. It is advantageous if the thread pitch S is at most 1.5 times the core diameter D _K.

The cutting thread 10 has thread flanks 11 on, the one flank width B in the thread root, ie in the core 9 , establish. According to the embodiment shown, the edge width B is 0.7 mm. It is advantageous if the flank width B is smaller than 0.2 times the core diameter D _K. According to the embodiment shown: B = 0.1 • D _K.

The thread flanks 11 include a flank angle α. The flank angle α of the cutting thread 10 is 50 ° in the embodiment shown. It is advantageous if the flank angle α is less than 60 °.

The thread flanks 11 have a flank height H _F. The flank height H _F results from the difference between the thread diameter D _G and the core diameter D _K. According to the embodiment shown: H _F = 1.5 mm.

The concrete screw 2 has a length Ls. The length Ls extends from a free end of the concrete screw 2 up to a concrete screw head 12 , which is designed as a flat head. According to the illustrated embodiment, the length Ls is 40 mm. The concrete screw head 12 Opposite arranged free end is an introductory 13 with which the concrete screw 2 in the dowels 5 is introduced. The concrete screw 2 is with a thread length L _E in the dowel 5 screwed. The engagement length L _E is smaller than the length Ls.

At the introductory 13 is provided a thread beginning with a reduced thread diameter D _G. The thread diameter D _G can be reduced at the beginning of the thread up to the core diameter D _K.

The dowel 5 has a dowel length L _D and a dowel outer diameter D _DA and a dowel inner diameter D _DI . The plug outer diameter D _DA is smaller than the bore diameter D _B. In the embodiment shown, the thread diameter D _{G is} smaller than the plug outer diameter D _DA , wherein in particular: D _G <0.9 • D _DA , in particular D _G <0.7 • D _DA , in particular D _G <0 , 5 • D _DA .

The dowel inner diameter D _DI is greater than or equal to the core diameter D _K , where: D _DI ≥ 1.01 • D _K , in particular D _DI ≥ 1.02 • D _K , in particular D _DI ≥ 1.04 • D _K , In the embodiment shown, the dowel inner diameter D _{DI is} smaller than the thread diameter D _G , where: D _DI <0.9 • D _G , in particular D _DI <0.8 • D _G , in particular D _DI <0, 6 • D _G.

The dowel 5 also has a dowel jacket 14 on, with the cutting thread 10 for propulsion in the dowel 5 in the dowel coat 14 cuts. For this purpose, the dowel coat 14 a dowel sheath thickness M _D on. The dowel sheath thickness M _D results from the difference between the dowel outer diameter D _DA and the dowel inner diameter D _DI . The anchor coat thickness M _D is greater than the flank height H _F The following applies: M _D > 1.5 mm. In particular: M _D > 1.05 • H _F , in particular M _D > 1.2 • H _F , in particular M _D > 1.4 • H _F.

The dowel 5 has at least one not shown fastener for securing the anchor 5 in the borehole 3 on. The fastening element can be designed as a sawtooth profile formed in the dowel jacket. Alternatively or additionally, spreading elements may be provided which are along the central longitudinal axis 8th are arranged. The spreading elements may be relative to the central longitudinal axis 8th an angle of in particular 45 °, in particular 40 °, in particular 35 °.

The cutting thread 10 extends along the core 9 in a threaded section A _{G of} the concrete screw 2 , The threaded portion A _G extends along the screw-in length L _E. In the embodiment shown, the dowel length L _{D is} greater than the engagement length L _E , where: L _D > 1.1 • L _E , in particular L _D > 1.2 • L _E , in particular L _D > 1.4 • L _E.

The threaded portion A _G closes along the central longitudinal axis 8th a thread-free shank portion A _S on. The shank portion A _S has a shank diameter D _S which is enlarged relative to the core diameter D _K. In particular: D _S ≥ 1.05 • D _K. In particular, the shank diameter D _S essentially corresponds to the dowel inner diameter D _DI . In particular: D _S > D _DI , in particular D _S > 1.005 • D _DI . This ensures that the concrete screw 2 maximum with the threaded section A _G in the dowel 5 is screwed in. Unintentional screwing in the concrete screw 2 with the shaft portion A _S is reliably prevented. It also prevents the free end of the concrete screw 2 over the end of the dowel 5 protrudes and thus the dowel 5 gets destroyed. The shank portion A _S stands on the free surface 7 of the material 4 above. An object can be held on the free shaft section As.

The transition from the core diameter D _K to the shaft diameter Ds is linear, ie along a frustoconical intermediate portion. The frusto-conical intermediate portion is part of the threaded portion A _G. The intermediate portion is adjacent to the shank portion to the threaded portion As A _G arranged. The intermediate section forms the transition from the threaded section A _G to the shaft section A _S.

The shaft section As closes along the central longitudinal axis 8th a head section A _K. The head section A _K comprises the concrete screw head 12 , The concrete screw head 12 has a screw head diameter D _SK , which is 15 mm according to the embodiment shown. In particular, D _SK ≥ 2 • D _K , in particular at least D _SK ≥ 2.2 • D _K , in particular D _SK ≥ 2.5 • D _K and in particular D _SK ≥ 2.7 • D _K. The concrete screw head 12 forms a fastening unit for securing an object to the concrete screw 2 , For example, between a bottom 15 the concrete screw head 12 and the surface 7 of the material 4 a held on the shaft portion As, not shown object are clamped.

According to the embodiment shown, the head section A _{K has} a tool section 16 on. According to the embodiment shown in FIG 3 is the tool section 16 as inner contour in the concrete screw head 12 executed. The inner contour is out of round with respect to the central longitudinal axis 8th , The non-circular contour is designed as an internal hexagon. The concrete screw 2 is screwed from above by means of a tool.

The following is with reference to the 4 A second embodiment of the concrete screw according to the invention 2 described. Structurally identical parts receive the same reference numerals as in the first embodiment, to the description of which reference is hereby made. Structurally different but functionally similar parts are given the same designation with a following a.

The main difference of the concrete screw 2a according to the second embodiment is the execution of the concrete screw head 12a as a countersunk head. The maximum screw head diameter D _SK is according to the embodiment shown 13 mm. The concrete screw head 12a is frustoconical. This means that the screw head diameter D _SK along the central longitudinal axis 8th is changeable. The maximum screw head diameter D _SK is at a free end of the concrete screw head 12a So at a free end 17 the concrete screw 2 arranged. The free end 17 is the introductory one 13 arranged opposite.

With appropriate preparation of the connection arrangement 1 , in particular the borehole depth T _B and the length L _{D of} the anchor 5 by removing the concrete screw 2a can be screwed in, the concrete screw 2a flush with the surface 7 of the material 4 or in the dowel 5 be recessed, leaving the concrete screw 2a on the surface 7 of the material 4 not survive. The unthreaded shaft portion As is shortened compared to the first embodiment. The head portion A _K with the frusto-conical countersunk head is integrated into the shaft portion As. The geometry of the core 9 and in particular the cutting thread 10 is at the concrete screw 2a identical as in the first embodiment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014222891 A1 [0003]
• DE 102014219116 A1 [0003]

Claims (17)

Self-tapping screw for screwing into a dowel - with a cylindrical core (9) with a core diameter (D _K ) and - with a threaded section (A _G ) with a cutting thread (10) for screwing the screw (2) into one Dowel jacket, wherein the cutting thread (10) has a thread diameter (D _G ) where: $${\text{D}}_{\text{G}}>{\text{D}}_{\text{K}},$$

Screw after Claim 1 characterized in that D _G ≦ 1.4 • D _K , in particular D _G <1.38 • D _K , in particular D _G <1.35 • D _K , in particular D _G <1.32 • D _K , in particular D _G <1.3 • D _K , in particular D _G <1.28 • D _K and in particular D _G <1.275 • D _K. Screw after Claim 1 or 2 , characterized by a flank angle (α) of the cutting thread (10), wherein in particular: α <60 °, in particular α <58 °, in particular α <55 °, in particular α <52 ° and in particular α ≤ 50 °. Screw according to one of the preceding claims, characterized by a thread pitch (S), where: S ≤ 1.5 • D _K , in particular S ≤ 1.2 • D _K , in particular S ≤ 1.15 • D _K , in particular S ≤ 1.12 • D _K , in particular S ≤ 1.1 • D _K , in particular S ≤ 1.0 • D _K , in particular S ≤ 0.9 • D _K , in particular S ≤ 0.85 • D _K and in particular S ≤ 0.8 • D _K. Screw according to one of the preceding claims, characterized by a flank width (B) in the thread root of the cutting thread (10), wherein in particular: B <0.2 • D _K , in particular B <0.18 • D _K , in particular B < 0.15 • D _K , in particular B <0.12 • D _K and in particular B ≤ 0.1 • D _K. Screw according to one of the preceding claims, characterized by a fastening unit for fastening an object to the concrete screw (2), wherein the fastening unit in particular has a one-piece molded concrete screw head (12) or a fastening thread with a corresponding fastening element. Screw according to one of the preceding claims, characterized by a tool section with a cross-sectional surface oriented perpendicular to the central longitudinal axis (8), which has a non-circular contour relative to the central longitudinal axis (8). Screw according to one of the preceding claims, characterized by a torque for screwing the concrete screw into the borehole (3) at most 14 Nm, in particular 12 Nm, in particular 10 Nm, in particular 9 Nm, in particular 8 Nm and in particular 7.5 Nm, in particular at most 7 Nm, in particular at most 6.5 Nm and in particular at most 6 Nm. Screw according to one of the preceding claims, characterized by a flank height (H _F ), where H _{F =} D _G - D _K , where in particular: H _F ≤ 0.4 • D _K , in particular H _F ≤ 0.2 • D _K , in particular H _F ≦ 0.1 • D _K. Connecting arrangement comprising - in a material (4) arranged borehole (3) with a borehole diameter (D _B ), - in the borehole (3) insertable dowel (5) with a dowel outer diameter (D _DA ) and - a Concrete screw (2) according to one of the preceding claims, wherein: D _G <D _DA . Connecting arrangement according to Claim 10 , characterized in that the material (4) is a porous material, in particular concrete, a material with cavities, in particular a tile, or a solid material, in particular natural stone. Connecting arrangement according to Claim 10 or 11 , characterized in that the dowel (5) has a length (L _D ) and the concrete screw (2) has a Einschraublänge (L _E ), where: L _D > L _E , in particular L _D > 1.1 • L _E , in particular L _D > 1.2 • L _E , in particular L _D > 1.4 · L _E. Connecting arrangement according to one of Claims 10 to 12 , characterized in that the dowel (5) is designed as a plastic dowel. Connecting arrangement according to one of Claims 10 to 13 , characterized in that the dowel (5) has at least one fastening element for fastening the dowel (5) in the borehole (3). Connecting arrangement according to one of Claims 10 to 14 , characterized in that the dowel (5) has a dowel inner diameter (D _DI ), where: D _DI ≥ D _K , in particular D _DI ≥ 1.01 • D _K , in particular D _DI ≥ 1.02 • D _K , in particular D _DI ≥ 1.04 • D _K. Connecting arrangement according to Claim 15 , characterized in that D _DI <D _G , in particular D _DI <0.9 • D _G , in particular D _DI <0.8 • D _G , in particular D _DI <0.6 • D _G. Connecting arrangement according to Claim 15 or 16 characterized by a dowel sheath thickness (M _D ), where M _D = D _DA - D _DI , wherein in particular: M _D ≥ H _F , in particular M _D ≥ 1.1 • H _F , in particular M _D ≥ 1, 2 • H _F , in particular M _D ≥ 1.4 • H _F.

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