TWI668376B - Concrete screw - Google Patents

Abstract

The present invention relates to a concrete screw (1) comprising: a head portion (3) comprising a head member (5) adapted to cooperate with a mounting tool; a first a shaft (7), the first shaft (7) being substantially uniform in shape and having a substantially uniform first diameter (d1); and a second shaft (9), the second shaft ( 9) is substantially uniform in shape and has a substantially uniform second diameter (d2). The concrete screw (1) further comprises: a front section (11), the front section (11) comprising an outer surface (13) and a front end (15); and a thread (17), the threads ( 17) having a substantially uniform third diameter (d3), and wherein the threads (17) are disposed on the second shaft (9) and the front section (11). The outer surface (13) of the front section (11) has a fourth diameter (d4) smaller than the first diameter, the second diameter, and the third diameter (d1, d2, d3), and wherein The equal thread (17) maintains its third diameter (d3) on the smaller fourth diameter (d4) of the front section (11).

Description

Concrete screw

The present invention relates to a concrete screw adapted for mounting a building element to concrete.

Metal dilators or special concrete screws can be used when mounting architectural elements such as guardrails, pipes and other support structures to concrete pedestals. Since concrete is an extremely hard material, conventional screws such as wood screws cannot be used because they cannot be cut into concrete as they can be cut into wood. Typically, the boreholes are pre-drilled in the concrete and the bores are sized to allow only the threads of the concrete screws to be cut into the surrounding concrete. These pre-drilled holes need to be sized to ensure a firm anchorage in the concrete and to ensure that the concrete screws can be inserted into the material without the use of excessive force. There are many problems to be overcome when installing building elements to concrete, such as hitting steel bars, pre-drilled holes that are too tight for screws, or pre-drilled with excessive debris due to pre-drilling. Drill holes out.

On larger building sites, there may be hundreds or even thousands of holes to be pre-drilled for future installation of building elements to concrete. This can result in situations where the individual drill holes do not wish to spend more time than absolutely necessary to drill out each hole. If the pre-drilled hole is too tight for the concrete screw or if there is too much debris left in the hole due to the hole (which produces the same effect), the screw may not be fully inserted into the hole, so Proof that the installation of concrete screws is difficult or even unsafe. If the person performing the installation attempts to solve the problem by applying excessive force to the screw, it may degrade the material properties of the screw, thereby making the installation potentially dangerous.

If the pre-drilled hole is not fully fitted to the concrete screw, then these problems will be noticed first and will have the greatest impact at the tip of the screw hitting the bottom of the hole, especially when drilling down the hole. Significantly, this is because there is a risk of excessive debris remaining at the bottom of the borehole due to the borehole. Tightly packed concrete debris can function in the same way as drilled shallow holes. A common way to handle concrete debris is to apply pressurized air or a vacuum cleaner or the like to the borehole to ensure removal of debris. However, this operation is time consuming and therefore a costly process.

There are also several concrete screws on the market that have been adapted to widen the cutting tip portion of the borehole. With this cutting tip portion, if the fit between the screw and the borehole is initially too tight, the over-tightening of the borehole is not a problem since the cutting tip portion will automatically widen the borehole. If the debris is scattered on the wall of the borehole, this also applies to the problem of debris.

WO 2014131615 A1 discloses a concrete screw comprising at least one slit groove for widening a borehole. The groove extends in the threaded base at least in a plurality of sections without interrupting the threaded coil. If the pre-drilled hole is too shallow, the concrete screw can thus be deeper into the concrete base.

However, the problem with this type of concrete screw may be that the widening of the borehole may not always be acceptable because it creates the risk of weakening the concrete structure. Since the widening of the borehole occurs when the concrete screw is installed into its final position, it is not possible to detect the state of the borehole when the concrete screw fills the borehole. Remove the screw for testing before reinstalling it again This means adding extra steps to the installer, which will be time consuming and therefore costly. In addition, this type of concrete screw can be used to widen the borehole, but it cannot be used in shallow boreholes to automatically make the borehole deeper, so the depth of the borehole and the presence of potential debris at the bottom of the borehole are still important. And can be problematic when the fit is not appropriate for the applied screw.

Therefore, there is a need for an improved concrete screw for mounting building elements to concrete that eliminates the disadvantages of the prior art. In addition, there is a need for concrete screws that are easy to use without adding extra steps to the installation program. It is also necessary to achieve reproducible and good results of concrete screws even if the pre-drilled holes are not adequately cleaned of potential debris.

Concrete screws in accordance with example embodiments of the present invention are intended for use in pre-drilled boreholes rather than being screwed directly into the material. Thus, the concrete screws used for the pre-drilled holes are generally different from the screws intended to be individually advanced into the material (i.e., without the need to pre-drill holes for receiving the screws).

The object of the invention relates to a concrete screw as defined in the prior art of the first variant and further defined by the features of the characterizing part of the technical solution 1.

The object of the present invention is directed to a concrete screw that is adapted to be insertable into a borehole in which debris is present after pre-drilling the borehole without having to be forced to drill the borehole deeper than necessary. It is further an object of the present invention to create a space for the debris without reducing the grip between the concrete screw and the pre-drilled bore. Therefore, the concrete screw is particularly useful for debris that is already present in the pre-drilled holes (i.e., debris located directly below the tip end portion of the concrete screw).

Concrete screws according to specific examples are intended for pre-drilled holes hole. The concrete screw includes a head portion including a head member adapted to cooperate with a mounting tool, a first shaft that is substantially uniform in shape, the first shaft having a substantially uniform first diameter; And a second shaft that is substantially uniform in shape, the second shaft having a substantially uniform second diameter. The concrete screw further includes a front section including an outer surface and a front end, and a thread having a substantially uniform third outer diameter, wherein the thread is disposed on the second shaft and the front section. The concrete screw is characterized in that the outer surface of the front section has a fourth diameter smaller than the first diameter, the second diameter and the third diameter, and wherein the threads maintain the third outer diameter in the front section Smaller on the fourth diameter.

This situation has the advantage that the debris remaining in the bore after pre-drilling the bore for inserting the concrete screw does not have to be removed before the concrete screw is inserted. This is because the fourth diameter of the front section is smaller than the diameter of the first shaft, the second shaft and the thread, respectively. This smaller fourth diameter creates a space for debris to fill. However, due to the smaller fourth diameter, the grip of the concrete screw is not reduced because the thread retains its outer diameter and thus maintains its grip on the borehole. In addition, when contacting the threads of the front section, the potential debris will move up the threads in the space between the concrete screw and the bore.

According to one aspect of the invention, the front section is formed as a substantially uniform shaped rod, wherein the fourth diameter is a substantially uniform diameter.

This situation has the advantage that the concrete screw will be stable and easy to manufacture, and has a large space for debris to be filled. A substantially uniform shaped rod will provide equal support for the threads on the front section, making it a mechanically strong device.

According to another aspect of the invention, the front section is formed as a truncated cone, wherein the fourth diameter of the front section is a decreasing diameter, wherein the fourth diameter decreases in a direction toward the front end.

This situation has the advantage that the concrete screw will have a large space for debris filling and the debris can be easily repositioned in the space due to the truncated cone shape. When contacting the threads of the front section, the debris will move up the thread in the space between the concrete screw and the borehole. The shape of the truncated cone near the bottom of the bore creates a larger volume of space that will reduce the amount of force required to relocate the debris up the thread, due to the close accumulation of debris at the bottom of the borehole. There will be less pressure on the chips.

According to another aspect of the invention, the outer surface of the front section includes at least one groove adapted to move debris in the borehole as the screw is inserted. Thereby, the debris moves in a direction from the front side toward the head portion of the concrete screw.

This situation has the advantage that the risk of stacking the debris in the borehole against the bottom of the borehole will be reduced, since at least one of the grooves will increase the space for debris to be repositioned and filled. The at least one groove will also help to move the debris along the length of the concrete screw to avoid pushing and pressing it between the front end of the concrete screw and the bottom of the borehole. For this purpose, the front section of the screw including the groove will be drilled into the debris at the bottom of the pre-drilled hole and the debris is moved away from the bottom by means of at least one groove. Therefore, the need to clean the pre-drilled holes prior to inserting the concrete screws into the holes is removed.

In accordance with still another aspect of the present invention, at least one of the grooves has a semi-circular surface, wherein the intersection of the semi-circular surface and the front end of the front section forms an acute angle.

This situation has the advantage that the groove will act like a blade and lift debris from the bottom of the borehole in an efficient manner. The acute angle at which the semi-circular surface intersects the front end of the front section will create a thin first contact edge towards the debris, thereby lifting the debris from the bottom of the borehole as the concrete screw rotates downwardly in the bore. Another advantage of having a groove in a semi-circular shape is Thus, making the groove will be easy and therefore cost effective because the grinding disk can simply be rotated against the concrete screw to achieve the desired shape.

According to a further aspect of the invention, the at least one groove has an inclined surface, wherein the intersection of the inclined surface with the front end of the front section forms an acute angle.

This situation has the advantage that the groove will act like a blade and lift debris from the bottom of the borehole in an efficient manner. The acute angle at which the inclined surface intersects the front end of the front section will create a thin first contact edge towards the debris, thereby lifting the debris from the bottom of the borehole as the concrete screw rotates downwardly in the bore. Another advantage of a groove having an inclined surface is that debris on the slope of the groove can be easily moved upwards and transported to adjacent threaded portions and continues to be moved away from the bottom of the borehole in an efficient manner by the threads.

According to yet another aspect of the invention, the length of the front section is in the range of from about 12% up to about 30% of the length of the threaded portion of the concrete screw.

This situation has the advantage that a sufficiently large portion of the concrete screw contains a smaller diameter front section that creates an equally large enough space for concrete debris to fill when the concrete screw is installed into the borehole.

According to one aspect of the invention, the length of the front section is in the range of from about 20% up to about 25% of the length of the threaded portion of the concrete screw.

This situation has the advantage that a sufficiently large portion of the concrete screw contains a smaller diameter front section that creates an equally large enough space for concrete debris to fill when the concrete screw is installed into the borehole.

1‧‧‧Concrete screws

3‧‧‧ head part

5‧‧‧ head components

7‧‧‧First shaft

9‧‧‧Second shaft

11‧‧‧Front section

13‧‧‧ outer surface

15‧‧‧ front end

17‧‧‧ thread

19‧‧‧ Groove

21‧‧‧Semicircular surface

23‧‧‧Sloping surface

25‧‧‧ deformation indicator

C‧‧‧ Center

D‧‧‧Distance

D1‧‧‧first diameter

D2‧‧‧second diameter

D3‧‧‧ third diameter

D4‧‧‧fourth diameter

R‧‧‧ Radius

‧‧‧‧ acute angle

''‧‧‧ acute angle

Preferred embodiments of the present invention will be further described with reference to the accompanying drawings.

Figure 1a shows a perspective view of a concrete screw in accordance with a first embodiment of the present invention.

Figure 1b shows a perspective view of a concrete screw in accordance with a second embodiment of the present invention.

Figure 2 shows a side view of a concrete screw in accordance with a third embodiment of the present invention.

Figure 3 shows a side view of a concrete screw according to a fourth embodiment of the present invention.

Figure 4 shows a side view of a front section of a concrete screw in accordance with a first embodiment of the present invention.

Figures 5a to 5c show different side views of a front section of a concrete screw in accordance with a second embodiment of the present invention.

Figure 6 shows a side view of a concrete screw according to a fifth embodiment of the present invention.

Herein, specific examples of the present invention will be described in detail with reference to the accompanying drawings. It will be appreciated that the invention may be modified in various ways without departing from the scope of the invention. Accordingly, the drawings are considered as illustrative in nature and not restrictive. All drawings may not be made to scale.

Figure 1a shows a perspective view of a concrete screw 1 according to a first embodiment of the invention. The concrete screw is intended for use in pre-drilled boreholes. The concrete screw 1 is adapted for mounting building elements to concrete articles or pedestals without the need to adequately clean potential concrete debris from pre-drilled holes in such concrete objects or pedestals. The concrete screw 1 is further adapted to be able to be installed in the uncleaned concrete borehole and still achieve a firm anchoring of the building elements being installed. The concrete screw 1 comprises: a head portion 3 comprising a head member 5 adapted to cooperate with a mounting tool; a first shaft 7, which is substantially uniform in shape, the first shaft having a substantially uniform first a diameter d1; and a second shaft 9, which is substantially uniform in shape, the second axis The rod has a substantially uniform second diameter d2. The concrete screw 1 further comprises: a front section 11 comprising an outer surface 13 and a front end 15; and a thread 17 having a substantially uniform third diameter d3, wherein the thread 17 is disposed in the second shaft 9 and the front section On segment 11. The outer surface 13 of the front section 11 has a fourth diameter d4 smaller than the first diameter d1, the second diameter d2, and the third diameter d3, and the thread 17 has its third diameter d3 kept smaller in the front section 11 The fourth diameter is d4. In this particular embodiment of the invention, the outer surface 13 of the front section 11 further comprises a recess 19 adapted to move debris in the borehole as the screw 1 is inserted, whereby the debris is at the front end 15 moves in the initial direction toward the head portion 3 of the concrete screw 1.

The groove 19 of this specific example has a semi-circular surface 21 in which the intersection of the semi-circular surface 21 and the front end 15 of the front section 11 forms an acute angle. The intersection of the semi-circular surface 21 forming the acute angle with the front end 15 of the front section 11 will act as a blade when the front end 15 of the concrete screw 1 engages the potential debris at the bottom of the borehole into which the concrete screw 1 is being installed. . The acute angle of the semi-circular surface 21 is positioned toward the head portion of the concrete screw 1 relative to the front end 15 of the concrete screw by centering the perceived circle (by which the grinding disc or the like forms a semi-circular surface 21) 3, but is achieved from the front end 15 not farther than the radius of the perceived circle (from the semicircular surface 21 from which the groove 19 is formed) (see Figure 4 and the accompanying description for more details).

The reduction in the diameter of the front section 11 relative to the first shaft 7 and the second shaft 9 of the concrete screw 1 creates a space for the concrete debris of the borehole to fill, and the appropriate semi-circular surface 21 of the front section 11 The relocation of debris from the front end 15 of the concrete screw 1 to the space around the front section 11 is assisted. In other words, the space for the debris is the volume between the side of the borehole for mounting the concrete screw and the outer surface 13 of the front section 11 of the concrete screw 1. Since the debris in the borehole can be repositioned to this volume, there is no need to clean the debris and there is no need to pre-drill the ratio The deeper depth of the hole necessary for the length of the thread 17 of the concrete screw 1 is a major factor with regard to how much load the concrete screw 1 can withstand when installed. Even if the fourth diameter d4 of the front section 11 is smaller than the threaded second shaft 9 of the concrete screw 1, the thread 17 of the front section 11 holding the outer third diameter d3 thereof gives the same bearing property to the concrete screw 1. As with the concrete screw 1, there will be no reduction in diameter. These combined features also give good bearing properties to the concrete screw 1 while typically eliminating the time consuming work of cleaning debris in the borehole prior to mounting the screw 1. The pre-drilling process is also more efficient because it does not need to be drilled deeper than necessary to create a space for debris as an alternative to not cleaning the debris. The specific examples described herein may have more than one groove 19; the two grooves 19 may be optimally disposed on opposite sides of the concrete screw 1 to enhance the debris movement effect of the present invention. The grooves can also have other shapes, for example as described with respect to Figure 1b.

Figure 1b shows a perspective view of a concrete screw in accordance with a second embodiment of the present invention. This second embodiment of the invention is similar to the first embodiment depicted in Figure 1, except that the shape of the recess 19 is excluded. In this particular embodiment of the invention, the recess 19 has an inclined surface 23, wherein the intersection of the inclined surface 23 with the front end 15 of the front section 11 forms an acute angle. This inclined surface 23, which also intersects the front end 15 of the concrete screw 1, will act as a blade in the same manner as the semicircular surface 21 of the groove 19 of the first embodiment. However, in this particular example, when the acute angle of the groove 19 engages the debris, the debris will be pushed up along the inclined surface 23 and pushed onto the thread 17 behind the inclined surface 23. The width of the groove can vary, but the inclined surface 23 of the groove will always intersect the front end 15 of the concrete screw 1 to achieve the desired effect of moving the debris away from the bottom of the borehole. Preferably, the width of the recess 19 will not be wider than the distance between the threads 17 on the same side of the concrete screw 1 in order to maintain the load bearing properties of the screw 1.

In both the first embodiment and the second embodiment, respectively depicted in Figures 1a and 1b, the length of the front section is about 20% of the length of the threaded portion of the concrete screw 1, the threaded portion It is the front section 11 together with the second shaft 9. The length of the first shaft 7 is based on the preferred thickness of the building element to be mounted to the concrete and typically not inserted into the borehole. The threaded portion of the concrete screw 1 is therefore a factor in determining the load carrying capacity of the concrete screw 1. The length of the front section 11 may vary from about 12% up to about 30% of the length of the threaded portion of the concrete screw 1, and more preferably about 20% of the length of the threaded portion of the concrete screw 1. It varies up to about 25%. This section is a sufficiently large portion of the desired space for the debris in the borehole, but does not significantly weaken the mechanical properties of the entire concrete screw 1 in a significant manner. The grooves 19 depicted in Figures 1a and 1b intersect the front end 15 of the concrete screw 1. This situation causes the groove 19 to interact with debris located below the screw 1. This interaction helps to ensure that the groove 19 can act as a blade for relocating debris. This situation is typically applicable regardless of the shape of the groove.

Figure 2 shows a side view of a concrete screw 1 according to a third embodiment of the present invention. In this particular embodiment of the invention, the front section 11 is formed as a rod of substantially uniform shape. The uniformly shaped rod has a fourth diameter d4 that is a substantially uniform diameter. In this view, it is easy to see that this fourth diameter d4 of the front section 11 is significantly smaller than the first shaft 7 and the second shaft 9 of the concrete screw 1, thereby creating a supply of warp when the screw is inserted into the borehole. Relocate the space filled with debris. The threads 17 of the concrete screw 1 disposed on the second shaft 9 and the front section 11 have substantially the same outer diameter d3 along the length of the screw 1. However, the arrangement of the threads 17 has a geometrical shape that decreases in width and thickness at the end portion of the outer surface 13 of the front section 11 and the front end 15 of the front section 13, because the thread 17 is oriented toward the concrete screw. 1 The front end 15 is elongated. This decreasing volume due to the smaller thickness and width is only around the entire circumference of the periphery of the concrete screw 1. About 40% up to about 80% range. Compared to the case where the threads 17 extend in the radial direction at different diameters d2, d4 of different sizes from the different portions of the screw 1, the concrete having substantially the same outer diameter d3 along the threaded region of the screw 1 The thread 17 of the screw 1 produces a longer effective load length. This situation produces a concrete screw 1 with a space for debris but which does not reduce the load bearing properties of the screw 1.

Figure 3 shows a side view of a concrete screw 1 according to a fourth specific example of the present invention. In this embodiment of the invention, the front section 11 is formed as a truncated cone, wherein the fourth diameter d4 of the front section 11 is a decreasing diameter. The fourth diameter d4 is decremented in the direction toward the front end 15. This specific example of the invention is similar to the embodiment of the invention depicted in Figure 2 except that the front section 11 is formed in the shape of a truncated cone rather than a rod. This situation creates a larger space for debris to fill and also reduces the area of the front end 15 of the concrete screw 1. The reduction in the area of the front end 15 also reduces the risk that debris that has not moved beneath the concrete screw when the concrete screw 1 is inserted is trapped and pressed between the front end and the concrete screw in the same process.

Figure 4 shows a side view of a front section 11 of a concrete screw 1 according to a first embodiment of the invention. The characteristics and functionality of this first specific example are the same as those described in the description of Figure 1a. However, in this view of the first specific example, it is easier to see the semicircular shape of the groove 19 of the concrete screw 1 and the second diameter d2 of the second shaft 9, the third diameter d3 of the thread 17, and the front portion. The width of the fourth diameter d4 of the segment 11. The acute angle α at which the semicircular surface 21 of the screw 1 intersects the front end 15 is also readily visible in this side view of the front section 11 of the first embodiment of the invention. This angle α can be changed by changing the radius R of the semicircular surface 21 of the groove 19 or moving the circle C (from which the semicircular surface 21 is obtained) along the length of the screw 1. In order to achieve the intersection between the semicircular surface 21 of the groove 19 and the front end 15 of the front section 11, the front end The distance D between 15 and the center C of the circle from which the semicircular surface 21 is obtained must be the same or shorter than the radius R of the circle. This distance D and/or radius can be modified within the scope of the invention to achieve a concrete screw 1 having a modified nature with respect to the angle a of the intersection of the semi-circular surface 21 of the groove 19 with the front end 15 and the concrete screw 1 Mechanical properties. The intersection of the semicircular recess 21 with the front end 15 causes the recess 21 to interact with debris located below the screw 1. This situation ensures that the groove 19 can act as a blade for relocating debris.

Figures 5a to 5c show different rotational side views of the front section 11 of the concrete screw 1 according to a second embodiment of the invention. The characteristics of this second embodiment are the same as those described in the description of Figure 1b. However, in such views of the second embodiment, the shape of the recess 19 and the inclined surface 23 of the recess 19 are shown in more nearsighted detail. The inclined surface 23 of the groove 19 and the acute angle α' of the intersection of the surface 23 with the front end 15 of the front section 11 are clearly visible and act as a function between the lower thread 17 when the concrete screw 1 is rotated by its insertional rotation. The inclined surface 23 of the blade can be easily understood after viewing the figures in the order of Figures 5a to 5c.

Figure 6 shows a side view of a concrete screw according to a fifth embodiment of the present invention. The nature and functionality of this particular example is the same as that described in the description of Figure 2, but with the added features of a plurality of deformation indicators 25 disposed on the periphery of the first shaft of the concrete screw. The deformation indicator 25 extends in a substantially longitudinal direction along the first shaft 7 of the concrete screw 1. This particular example is adapted for reuse in multiple installations of building elements, with no use, except that it is not necessary to remove debris in such boreholes prior to installing the concrete screws in the borehole in accordance with the specific examples described above. The risk of degrading mechanical properties of concrete screws 1 . If the concrete screw 1 is new and the force has not yet been applied to the screw 1, the direction of the deformation indicator 25 will be parallel to the outer circumference of the first shaft 7. However, if the concrete screw 1 has been used in the previous installation procedure (where concrete In the case that the screw has been exposed to the momentum/torque which is sufficiently large for the material of the concrete screw 1 to plastically deform it, the direction of the deformation indicator 25 will not be parallel with respect to the outer circumference of the first shaft 7 due to mechanical deformation. . Depending on the amount of deformation, when the deformation indicator 25 is compared with the outer circumference of the first shaft 7, its direction and distribution will be inclined or distorted in appearance, giving a clear view of the mechanical deformation of the material of the concrete screw 1. And a valid indication. Thus, the user will see and know that the concrete screw 1 has been mechanically deformed and it will not be able to maintain the same amount of load as before the deformation. The concrete screw 1 can then be properly disposed of and the new screw 1 should be used in its position. The deformation indicator 25 will thus give a clear visual indication of the mechanical properties of the concrete screw 1. The deformation indicator 25 can be provided as a plurality as described above, but other variations are also possible. A single deformation indicator 25, or two deformation indicators 25 arranged in pairs, or a plurality or more pairs of deformation indicators 25 may also be used. The deformation indicator 25 may be formed as a protrusion on the circumference of the first shaft 7 of the concrete screw 1, or as a groove, or a combination of both. The protrusions and grooves may have different shapes, such as triangular, cubic, polygonal or circular shapes. The one or more deformation indicators 25 may also be formed by surface treatment methods such as painting, applying a rotating wire brush, polishing, stamping, or other methods.

The invention is not limited to the specific embodiments presented. Combinations of features between different specific examples are possible. Accordingly, the drawings and description are to be considered as illustrative rather

Claims (9)

A concrete screw (1) for pre-drilled borehole, comprising: a head portion (3) comprising a head member (5) adapted to cooperate with a mounting tool, a first shaft a rod (7) having a substantially uniform rod shape, the first shaft having a substantially uniform first diameter (d1) and a second shaft (9) having a substantially uniform rod shape, the first The two shafts have a substantially uniform second diameter (d2), a front section (11) comprising an outer surface (13) and a front end (15), and a thread (17) having substantially a uniform third diameter (d3), wherein the threads (17) are disposed on the second shaft (9) and the front section (11), characterized by the front section (11) The outer surface (13) has a fourth diameter (d4) smaller than the first diameter, the second diameter, and the third diameter (d1, d2, d3), and wherein the threads (17) make it third The diameter (d3) is maintained on the smaller fourth diameter (d4) of the front section (11). A concrete screw (1) according to claim 1 wherein the front section (11) is formed as a substantially uniform shaped rod, wherein the fourth diameter (d4) is a substantially uniform diameter. The concrete screw (1) of claim 1, wherein the front section (11) is formed as a truncated cone, wherein the fourth diameter (d4) of the front section (11) is a decreasing Diameter, wherein the fourth diameter (d4) decreases in a direction toward one of the front sections (11). A concrete screw (1) according to any one of the preceding claims, wherein the front section (11) The outer surface (13) comprises at least one groove (19) adapted to move debris in a borehole when the concrete screw (1) is inserted, whereby the debris is The front end (15) is moved in the direction of one of the head portions (3) of the concrete screw (1). A concrete screw (1) according to claim 4, wherein the groove intersects the front end (15) of the concrete screw (1). A concrete screw (1) according to claim 5, wherein the at least one groove (19) has a semicircular surface (21), wherein the semicircular surface (21) and the front section (11) The intersection of the front ends (15) forms an acute angle (α). A concrete screw (1) according to claim 5, wherein the at least one groove (19) has an inclined surface (23), wherein the inclined surface (23) and the front end of the front section (11) The intersection of (15) forms an acute angle (α'). The concrete screw (1) of any one of claims 1 to 3, wherein the length of the front section (11) is about 12% of the length of the threaded portion of the concrete screw (1) to About 30% of the range. The concrete screw (1) of any one of claims 1 to 3, wherein the length of the front section (11) is about the length of the threaded portion of the concrete screw (1) From 20% to about 25%.