EP1872021A1

EP1872021A1 - Thread-cutting masonry screw

Info

Publication number: EP1872021A1
Application number: EP06723994A
Authority: EP
Inventors: Jan-Christian Becker; Oliver Hacker; Klaus Mayer; Marc Schäffer
Original assignee: Fischerwerke Artur Fischer GmbH and Co KG
Current assignee: Fischerwerke GmbH and Co KG
Priority date: 2005-04-16
Filing date: 2006-04-04
Publication date: 2008-01-02
Also published as: CN101160471A; US20090022568A1; JP2008537989A; WO2006111267A1; DE102005017596A1; AU2006237073A1; ZA200707750B; KR20080005917A

Abstract

According to the invention, the holding force of a thread-cutting masonry screw (1 ) in a drilled hole (2) in concrete (3) may be improved, whereby the masonry screw (1) is embodied with two thread pitches (8, 9) of differing outer diameter (d1,d2), whereby, viewed from the front screw end (5), a separation (P1) of the thread pitch (8) with the smaller outer diameter (d1) to the thread pitch (9) with the larger outer diameter (d2) is less than a separation (P2) of the thread pitch (9) with the larger outer diameter to the thread pitch (8) with the smaller outer diameter. The thread pitches (8, 9) are preferably sawtooth threads.

Description

description

Thread cutting concrete screw

The invention relates to a thread-cutting concrete screw for screwing into a hole in concrete, masonry or the like.

Concrete screws are screwed without dowels or the like. In a pre-drilled hole in concrete, masonry or the like. Its thread cuts into a borehole wall. A core diameter of the concrete screw is smaller than a borehole diameter so that there is a gap between the screw core and the borehole wall. An example of such a concrete screw is disclosed in EP 623 759 B1.

The invention has for its object to provide a thread-cutting concrete screw! 0, the high holding force at an acceptable screwing or

Has screwing energy.

This object is achieved by the features of claim 1. The concrete screw according to the invention has two threads with different

! 5 outer diameters and different distances from each other in both

Axial directions of the concrete screw on. With different pitches of the threads from each other, it is meant that the distance from one thread to the other thread in one axial direction of the concrete screw is smaller than in the other axial direction. The threads are thus located outside the middle äθ two successive turns of the other thread. Of the

Borehole diameter should be smaller than an outer diameter of the smaller thread, so that also cuts the thread with the smaller outer diameter in the borehole wall and contributes to the maintenance of the concrete screw in the concrete.

55 The two threads with different outside diameters transmit the force more evenly and better distributed in the concrete than a single thread and also as two threads with the same outside diameters. Another advantage is an improved setting feeling for a user when screwing the concrete screw into the borehole, the concrete screw screws and cuts better into the borehole.

Also, the different pitches of the threads in both directions of the concrete screw improve the power transfer from the concrete screw to the concrete. The distances of the threads are chosen from each other so large that

Drill flour that has remained in the well bore after drilling and that results from cutting the threads into the borehole wall has sufficient clearance between the threads and between a core of the concrete screw and the borehole wall.

In a preferred embodiment of the invention, the distance of the thread with the smaller outer diameter of the thread with the larger outer diameter in the direction of a front screw end of the concrete screw is greater than in the direction of a rear screw end of the concrete screw. The front end of the screw is the one with which the concrete screw is screwed into the borehole in advance. The rear end of the screw usually has a screw head and is provided for attaching a rotary tool or a rotary impact tool. Seen from the thread with the larger outer diameter of the thread with the smaller outer diameter in the direction of the front end of the screw on a smaller distance than in the direction of the rear end of the screw. As a force is transferred from the concrete screw to the concrete from the threads towards the rear end of the screw to the concrete, the force from the thread having the smaller outer diameter, which cuts less deeply into the borehole wall, becomes the shorter distance toward the rear Screw end of the thread with the larger outside diameter and of the

Larger outside diameter thread, which cuts deeper into the borehole wall, is transferred to the concrete on the rear screw end longer distance to the next turn of the smaller diameter thread of the thread. The power transmission from the concrete screw to the concrete is thereby improved. In a preferred embodiment, the ratio of the outer diameter of the thread having the larger outer diameter to the outer diameter of the thread having the smaller outer diameter is about 1.03 to 1.14. The larger outer diameter may be up to about 20% larger than the smaller outer diameter. This diameter ratio of the outer diameter of the two threads has been found to be favorable for a high holding force of the concrete screw in the concrete.

The ratio of outer diameter of the thread with the larger outer diameter to a pitch of the threads of the concrete screw is in one embodiment of the invention about 0.9 to 1, 2. The slope is the axial

Distance between successive turns of a thread.

The ratio of the outer diameter of the thread having the larger outer diameter to a core diameter of the concrete screw in one embodiment of the invention is about 1.2 to 1.4, preferably about 1.25 to 1.35 and in particular 1.27 to 1.32. In particular, the latter ratio has proven to be favorable for a high holding force of the concrete screw in concrete at an acceptable screwing. Comparable good holding values and screwing moments are conceivable with the larger tolerance fields anyway.

A flank angle α of one or both threads of the concrete screw is in an embodiment of the invention about 40 ° to 50 °. The threads can be pointed threads with equal flank angles on both sides of the threads. An embodiment of the invention provides a Sägezahngewinde for one or both threads of the concrete screw, preferably those for the front

Screw end pointing thread flank steeper and pointing to the rear end of the screw thread flank is flatter. The front thread flank has an angle of, for example, about 80 ° to 90 ° to the axial direction, so it is radially or at an angle of up to about 10 ° to a radial. The flank angle between the two flanks of each thread remains unchanged between about 40 ° and 50 ° or is blunter. The greater inclination of the trailing edge of the threads in a buttress thread improves the transmission of power from the thread to the concrete.

The claim 8 is on the screwed into a hole in concrete, thread-cutting concrete screw in the above-described embodiments directed. In this case, the ratio of pitch of the threads of the concrete screw to the borehole diameter in a preferred embodiment of the invention about 1, 01 to 1, 45th The ratio of outer diameter of the thread with the smaller outer diameter to the borehole diameter is in an embodiment of the invention about 1.01 to 1.15 and the ratio of

Core diameter of the concrete screw to the borehole diameter in an embodiment of the invention about 0.95. These design rules, which can be implemented individually or in any combination in embodiments of the invention, have proven to be favorable in terms of holding the concrete screw in concrete.

In a preferred embodiment of the invention, the ratio of a distance of the threads from one another in the direction of the rear screw end of the concrete screw to a penetration depth of the respective thread into the borehole wall about 8: 1. The penetration depth is 1/2 of the difference between the outer diameter of the respective thread and the hole diameter. Since the pitch of the threads is different from each other as seen in the direction of the rear end of the screw screw, smaller in the thread with the smaller outer diameter and larger in the thread with the larger outer diameter, the specified ratio of the pitch of the threads to the penetration depth for both threads at least be realized in about. The ratio is also dependent on the concrete strength. This embodiment has proven to be favorable for a high power transmission from the threads to the concrete.

The invention will be described below with reference to a drawing

Embodiment explained in more detail. The single FIGURE shows a concrete screw according to the invention, which is screwed a little way into a borehole. The drawing is not to scale.

The illustrated in the drawing, thread-cutting according to the invention

Concrete screw 1 is provided for screwing into a borehole 2 in concrete 3, masonry or the like. The concrete screw 1 is screwed into the borehole 2 without the use of a dowel or other auxiliary means.

The concrete screw 1 has a frusto-conical taper 4 at a front

End of the screw 5 and a screw head 6 at a rear end of the screw 7. In the illustrated embodiment, the screw head 6 is a hexagonal head, this head shape is not mandatory.

The concrete screw 1 has two threads 8, 9 with different outside diameters. An outer diameter d, of the thread 8 with the smaller outer diameter d- is greater than a borehole diameter D, so that when screwing the concrete screw 1 into the borehole 2, both threads 8, 9 cut into a borehole wall 10. The threads 8, 9 are located outside of a center of the turns of the other thread 8, 9 is viewed from the front end of the screw 5, a distance P ₁ from the thread 8 with the smaller diameter Cl ₁ to the thread 9 d having the larger external diameter ₂ smaller than a distance p ₂ from the thread 9 with the larger outer diameter d ₂ to the thread 8 with the smaller outer diameter d- ,. The pitch p of the concrete screw 1 is the distance from one turn of a thread 8, 9 to the following turn of the same thread 8, 9, so the

Sum of the distances P _1, p _{2 of} the threads 8, 9 from each other.

The threads 8, 9 can be designed as a pointed thread with a flank angle of, for example, about 40 ° to 50 ° (not shown). In the illustrated and described embodiment of the invention, the threads 8, 9 than

Sawtooth thread running, with a steeper flank 11, 12 of the threads 8, 9 to the front end of the screw 5 and a flatter thread flank 13, 14 to the rear end of the screw 7 has. The front flank 11, 12 of the threads 8, 9 has an angle of about 80 ° to 90 ° to an axial direction of the concrete screw 1, in the illustrated and described embodiment, the angle is 80 °, i. the front flank 11, 12 of the threads 8, 9 is almost radially from the concrete screw 1 from. The flank angle α between the two flanks 11, 13; 12, 14 of the threads 8, 9 is 60 °, so that the rear edge 13, 14 of the threads 8, 9 is at an angle of 40 ° to the axial direction of the concrete screw 1. In particular, the inclination of the rear thread flanks 13, 14 of the

Threads 8, 9 which form a frustoconical, winding around a threaded core 15 of the concrete screw 1 surface are for a holding force of the concrete screw 1 in the concrete 3 determining or at least co-determining.

The ratio of an outer diameter d _{2 of} the thread 9 with the larger

Outer diameter to the core diameter d _κ of Gewindekems 15 is 1, 3, the Outer diameter d _{2 of} the thread 9 with the larger outer diameter d ₂ is about 10-12% larger than the outer diameter d _{1 of} the thread 8 with the smaller outer diameter di.

The ratio of the outer diameter d _{2 of} the thread 9 with the larger

Outside diameter to the pitch p of the concrete screw is 1 or a little more.

The ratio of the distances P _1, p _{2 of} the threads 8, 9 from each other, as seen from the front end of the screw 5, to the penetration depth of the respective thread 8, 9 in the borehole wall 10 is about 8: 1. Here is the penetration depth

1/2 of the difference between the respective outer diameter d _2ι d _{1 of} the threads 8, 9 and the borehole diameter D (1/2 (d ₂ - D) bzw.1 / 2 {d ^ - D)). Since the distances P ₁ , p _{2 of} the threads 8, 9 are different from each other, the said ratio, despite the different outer diameter of the threads 8, 9, at least approximately for both threads 8, 9 comply. Since the

Thread 8 with the smaller outer diameter d., A smaller depth of penetration into the borehole wall 10, the required support length in the axial direction until the next thread 9 for transmitting a pull-out force from the concrete screw 1 to the concrete 3 is smaller than the thread 9 with the larger outer diameter d ₂ . The said ratio of 8: 1 seems to give an optimal value for the transmission of force from the threads 8, 9 to the concrete 3 and thus a high holding force of the concrete screw 1 in the concrete 3 or at least to be close to the optimum value.

The ratio of the pitch p of the threads 8, 9 of the concrete screw 1 to

Diameter D of the borehole 2 is about 1, 2, the ratio of the outer diameter d of the thread 8 with the smaller outer diameter d., To the diameter D of the borehole 2 is about 1, 1. The ratio of the diameter D _{κ of} the thread core 15 of the concrete screw 1 to the hole diameter D is about 0.95, so that a gap between the

Thread core 15 and the borehole wall 10 is made. The screwing the concrete screw 1 in the hole 2 is thereby improved or even possible. In the intermediate space, drilling dust can collect from the drilling of the borehole 2 and from the cutting of the threads 8, 9 into the borehole wall 10 when the concrete screw 1 is screwed in.

Claims

claims

1, thread-cutting concrete screw for screwing into a borehole in concrete, characterized in that the concrete screw (1) has two threads (8, 9) that the threads (8, 9) different

Have outer diameter (d _{1 (} d ₂ )) and that a distance (P ₁ , p ₂ ) of the threads (8, 9) from each other in both axial directions of the concrete screw (1) is different.

2. Concrete screw according to claim 1, characterized in that the distance of the thread (8) with the smaller outer diameter (d-,) of the thread (9) with the larger outer diameter (d ₂ ) in the direction of a front screw end (5) of the concrete screw (1) is greater than in the direction of a rear screw end (6) of the concrete screw (1).

3. Concrete screw according to claim 1, characterized in that the outer diameter (d ₂ ) of the thread (9) with the larger outer diameter by up to about 20% greater than the outer diameter (d-,) of the thread (8) with the smaller outer diameter is.

4. Concrete screw according to claim 1, characterized in that the ratio of the outer diameter (d ₂ ) of the thread (9) with the larger outer diameter to the pitch (p) is about 0.9 to 1, 2.

5. concrete screw according to claim 1, characterized in that the ratio of the outer diameter (d ₂ ) of the thread (9) with the larger outer diameter to a core diameter (d _κ ) of the concrete screw (1) is about 1, 2 to 1, 4.

6. Concrete screw according to claim 1, characterized in that a thread (8, 9) of the concrete screw (1) has a flank angle (α) of about 40 ° to 60 °.

7. concrete screw according to claim 1, characterized in that a

Thread (8, 9) of the concrete screw (1) has a Sägezahngewinde.

8. In a borehole (2) in concrete (3) screwed, thread-cutting concrete screw (1), characterized in that the concrete screw (1) has two threads (8, 9) that the threads (8, 9) different

Have outer diameter (d ,, ,, ₂ ) and that a distance (P ₁ , p ₂ ) of the threads (8, 9) from each other in both axial directions of the concrete screw (1) is different.

9. In a borehole (2) in concrete (3) screwed, thread-cutting

Concrete screw according to claim 8, characterized in that the ratio of a distance (P ₁ , p ₂ ) of the threads (8, 9) from one another in the direction of a rear screw end (6) of the concrete screw (1) to a penetration depth of the thread (8, 9) into a borehole wall (10) is about 8: 1.

10. In a borehole (2) screwed in concrete (3), thread-cutting concrete screw (1) according to claim 8, characterized in that the ratio of a pitch (p) of the threads (8, 9) of the concrete screw (1) to the borehole diameter ( D) is about 1.01 to 1.45.

11. In a borehole (2) screwed into concrete (3), thread-cutting concrete screw (1) according to claim 8, characterized in that the ratio of the outer diameter (d.,) Of the thread (8) with the. smaller outer diameter to the borehole diameter (D) is about 1, 01 to 1, 15.

12. In a borehole (2) in concrete (3) screwed, thread-cutting concrete screw (1) according to claim 8, characterized in that the ratio of the core diameter (d _κ ) of the concrete screw (1) for

Borehole diameter (D) is about 0.95.