EP2962000A1

EP2962000A1 - Concrete screw

Info

Publication number: EP2962000A1
Application number: EP14704138.8A
Authority: EP
Inventors: Tobias Neumaier; Mark Winkler; Guenter Domani; Corinna Achleitner
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2013-02-26
Filing date: 2014-02-12
Publication date: 2016-01-06
Also published as: DE102013203151A1; WO2014131615A1; TW201447118A; US20160003284A1; CN105008730A

Abstract

The invention relates to a concrete screw having a shaft (31) and a screw thread (33) arranged on the shaft and a threaded coil (13) and a threaded base (14). According to the invention, in the end area (41) of the shaft, inside the shaft, at least one cut-out recess (36) for widening a borehole is provided, said recess extending, at least in sections, inside the thread base without interrupting the threaded coil. The invention also relates to a flat die for producing said type of concrete screw. The invention further relates to a method for producing a concrete screw.

Description

concrete screw

The invention relates to a concrete screw according to the preamble of claim 1. Such a concrete screw is equipped with a shaft and a shaft arranged on the thread with a thread and a thread root. The invention further relates to a rolling die for producing a concrete screw according to the preamble of claim 1 1 with a plurality of grooves for rolling a thread. The invention also relates to a manufacturing method according to claim 14 for a concrete screw according to the invention.

A generic concrete screw is known for example from EP 2 233 757 A2. This document teaches to provide cutting recesses in the lateral surface of the shank of the concrete screw which are bounded by sharp edges. These edges can serve as cutting edges that can widen a non-ideal cylindrical hole when screwing in the screw. Therefore, concrete screws with relatively large core diameter can be set with relatively low insertion torque due to the cutting recesses, so that relatively high loads can be achieved. A manufacturing method for a concrete screw with cutting recesses is known from US 2011274516 A. According to US 201 1274516 A, a thread is first formed on the screw shaft. Then, notches are cut out of the shank and the thread by means of inclined cutting wheels, which form the cutting recesses.

From EP 1 738 844 A1 a rolling jaw for screws with drill bit and scraping groove is known, wherein the scraping groove is rolled by means of the rolling die in a single operation during rolling of the thread. For this purpose, the rolling die of EP 1 738 844 A1 has projections for introducing the cockroach groove. The screws with drill bit known from EP 1 738 844 A1 are not intended for a concrete substrate.

DE 38 23 834 A1 describes a wood screw provided on the cylinder core of the thread, generated in the screw production points of engagement of drivers, which over the greater part of the length of the screw thread at regular intervals distributed on the cylinder core are arranged.

The object of the invention is to provide a concrete screw with which particularly good load values can be achieved with a particularly low production cost and good settability, and to provide a tool and a method for producing such a screw.

The object is achieved by a concrete screw with the features of claim 1, a rolling die with the features of claim 1 1 and a manufacturing method having the features of claim 14. Preferred embodiments are given in the respective dependent claims.

A concrete screw according to the invention is characterized in that at least one cutting recess for expanding a borehole is provided in the tip region of the shaft in the shaft, which extends at least partially within the thread root, without interrupting the thread turn.

The invention has recognized on the one hand that an axial superimposition of the cutting recesses with the thread often brings advantages in concrete screws. On the one hand, the cutting edges can cut the path for the shaft particularly efficiently when they are arranged at the tip region of the screw. On the other hand, it may be advantageous in view of the payloads to make the thread helix as long as possible and preferably also to lead them into the tip area. Because when the thread turns deep into the hole, loads are placed deep into the concrete, so that premature breakage of the screw is prevented. However, the invention has now further recognized that the axial interference of the cutting recesses with the thread may also be disadvantageous under certain circumstances and in certain applications. For if, due to this superimposition, the thread helix in the tip region is interrupted by the cutting recess, this can entail that the undercut surface is reduced and / or the supporting surface precisely in the area which is substantially responsible for the deep load transfer into the concrete and thus for the removal loads Thread coil is weakened. Building on this knowledge, the invention proposes to extend the cutting recess into the thread without, however, interrupting the thread helix with the cutting recess. As a result, the benefits can be realized, resulting from an overlap of thread and cutting recess, without the disadvantages set by a break in the thread helix under certain Circumstances can result. In particular, thus, a concrete screw can be provided with the good settability particularly good extraction loads can be achieved. In addition, cutting recesses that do not break the thread, as explained in more detail below can be made in a very simple manner in one and the same process step, so that a particularly low production cost is given.

The invention relates to a concrete screw, ie a screw with a self-tapping thread turn, which can be screwed to form a counter-thread in a concrete structure. The cutting recess has, expediently at its edge, at least one cutting edge with which a concrete building body can be cut to widen the borehole. The cutting recess forms a recess in the lateral surface of the shaft, which can absorb accumulating concrete flour during expansion, and thus can ensure a continuous cutting action.

Under the tip of the shaft, in particular, the end of the shaft can be understood, which is introduced in the intended use of the screw first in the wellbore in the building and / or the end, which is opposite to an optionally existing screw head. The tip region may be understood to mean a contiguous region that runs near the tip and / or includes the tip. In particular, under the tip region, a region can be understood in which the self-tapping thread helix begins. In a concrete screw, the tip is often not pointed, but has a flat face, since concrete screws are usually self-tapping, but not self-drilling.

Under the thread root according to the invention can be understood in particular the area which is enclosed by the thread spiral, that is, the region of the thread, which, viewed in the longitudinal direction of the thread and / or the shaft, is bounded on two opposite sides by the thread helix. According to the invention, the thread root, as typical for a concrete screw, viewed in the longitudinal direction of the thread and / or the screw can be significantly wider than the thread helix, preferably by at least a factor of 2, 3 or 4 wider. Additionally or alternatively, the thread root, as typical for a concrete screw, viewed in the longitudinal section of the screw at least approximately flat. The thread root, which can also be referred to as a thread groove, can be formed in particular by the lateral surface of the shaft. The thread root and / or the helical thread is or are suitably made spirally. Expediently, the shaft has at least in some areas a cylindrical guide. on the surface. Preferably, the thread according to the invention is completely continuous, so nowhere interrupted.

An advantageous embodiment of the invention is that the cutting recess is interrupted at least once by the thread helix of the thread. According to this embodiment, the cutting recess has at least two partial regions, which are separated from one another by the thread helix. The two subregions are preferably aligned with one another, in particular they may lie on a straight line. According to this embodiment, a cutting recess that is particularly extended in the longitudinal direction of the screw and thus effective can be realized.

In principle, the cutting recess can run completely within the thread root without interrupting the thread turn. However, it is particularly preferred that the cutting recess extends in regions outside the thread root. Accordingly, the cutting recess extends in regions outside the thread, that is to say also into a region of the skirt surface which, viewed in the longitudinal direction of the shank, is limited only on one side by the thread turn. This makes it possible to guide the cutting recess particularly close to the tip of the screw, so that the well can be widened particularly effective. As a result, inter alia, a taper of the shaft at the tip area can be dispensed without the settability suffers.

In particular, it can be provided that the cutting recess is open towards the end side of the shaft. Preferably, according to this embodiment, the cutting recess is visible in a plan view of the tip viewed in the longitudinal direction of the shaft. This embodiment can further improve the settability, on the one hand because the cutting action hereby already occurs directly at the top, and on the other hand because a removal of concrete flour from the cutting recesses is particularly easy hereby possible.

Furthermore, it is preferred that the cutting recess runs at least in regions within the first turn of the thread root starting from the thread beginning. This also makes it possible to realize a cutting action close to the tip and thus a particularly good settability. Under the thread beginning can be understood in the usual way, the end of the thread, which cuts into the concrete structure when screwing the screw first. In particular, the first 360 ° of the circulation path of the thread root around the longitudinal axis of the shaft can be understood as the first wall of the thread root. An advantageous embodiment is that the depth of the cutting recess is at least 0.05 times, preferably at least 0.1, times the shaft diameter. Such relatively deep cutting recesses can absorb the concrete flour accumulating during the expansion of the borehole particularly well. The depth can be measured in particular in the radial direction of the shaft.

Another advantageous embodiment is that the cutting recess viewed in cross-section of the shaft is asymmetrical. In particular, the cutting recess may be asymmetrical with respect to the radial direction of the shaft. As a result of the asymmetrical design, the deformation resistance during molding of the cutting recess can be reduced without the screw losing any significant function.

It is particularly expedient that viewed in the screwing-in direction of the thread helix flank of the cutting recess viewed in the cross-section of the shank, viewed more flatly with respect to the shell surface of the shank, runs as a flank of the cutting recess following in the screwing-in direction. The trailing edge in the screwing direction is the flank which cuts the concrete during screwing in the finished concrete screw. On this flank, a steep angle is advantageous for a good cutting action. The opposite, in the screwing of the thread helical leading edge of the cutting recess, however, has at most a subordinate cutting function. This flank is preferably made flat, since hereby the cutting recess can be configured with a large surface, so that the cutting recess can absorb concrete flour particularly reliably. A flat flank profile can be understood in particular to mean that said flank, viewed in the cross-section of the shank, only encloses a small angle with a tangent to the lateral surface of the shank, which arises at the transition of the lateral surface into said flank.

A further advantageous embodiment consists in that at least one further cutting recess is provided in the shank, which lies for the free cutting of the thread helix in the continuation of the thread helix. Such a further cutting recess, which lies in the continuation, that is to say in the fictitious extension of the helical thread turn, can cut free the area of the thread turn and thus further simplify the setting of the screw.

In particular, it can be provided that in the tip region of the shaft in the shaft a plurality of cutting recesses are provided for expanding the borehole, which run at least partially within the thread root, without interrupting the thread helix. Due to the large number of similar cutting recesses distributed over the circumference of the screw and thus particularly uniform cutting action can be achieved, which can further support the setting process

It can preferably be provided at least one Zusatzgewindewendel which extends at least partially in the thread root, in particular on the opposite side of the tip region of the thread. Such a Zusatzgewindewendel can serve, for example, for centering and / or form an additional safeguard against unscrewing the screw. Suitably, the auxiliary helix has a smaller number of turns than the helix and / or the pitch of the helix is less than or equal to the helix height. In a multi-start thread, the Zusatzgewindewendel can also serve for cutting into the concrete and have similar dimensions as the thread helix.

It is particularly expedient that the screw has a widened compared to the shaft screw head. This screw head can serve for rotationally fixed coupling with a setting tool. The screw head can for non-rotatable coupling with a setting tool, for example, a polygon structure, preferably a hexagon, have.

The invention can be used in particular in connection with concrete screws with a relatively thick shaft, so for example in such screws in which the ratio of the outer diameter of the thread to the core diameter of the shaft 1, 1 to 1, 4. In such screws, the cutting edges formed on the cutting recesses can be particularly effective. The screw is preferably made of a metal material.

An inventive rolling jaw for producing a concrete screw, preferably for producing a concrete screw described in this text, is formed with a plurality of grooves for rolling a thread. It is characterized in that it comprises at least one projection for rolling a cutting recess, which does not interrupt the grooves for rolling the thread. With such a rolling jaw screws can be made with Schneidausnehmungen in a particularly simple manner, which leave the threaded helices of the screw thread intact. As already explained above, particularly good extraction loads can be achieved with good setting properties. In order to the grooves are suitable for rolling a thread, they preferably form a thread counter profile. Preferably, the projection of at least one of the grooves is interrupted.

The rolling jaw is preferably a flat-rolled jaw, that is to say in particular a rolling jaw with a substantially flat working surface, which is preferably moved exclusively linearly in the rolling process.

It is particularly preferred that the rolling jaw has at least one projection set consisting of a plurality of projections for multi-stage rolling one and the same cutting recess. Thus, there are provided a plurality of projections which act on one and the same cutting recess successively and reshape. These projections form a projection set. According to this embodiment, even deep cutting recesses can be rolled with particularly good thread quality. If the screw has a plurality of cutting recess, a plurality of projection sets may be present, each of which transform one of the cutting recesses step by step. In particular, the various projection sets can intermesh and form an interdigital structure.

For a good rolling result, it is particularly advantageous that the height of the projections of the projection set at least partially increases in the working direction of the rolling die. Under the working direction can be understood in particular the direction in which the workpiece moves during rolling on the rolling die.

In a method for producing a concrete screw according to the invention, both the thread helix and the cutting recess are formed in the same thread rolling process, preferably by means of a rolling jaw according to the invention. Accordingly, the cutting edge production in the forming manufacturing process for the thread is integrated, so that a particularly simple and fast production is given.

It is particularly preferred that the cutting recess is formed by a plurality of projections which are arranged one behind the other on one and the same rolling die. According to this embodiment also deep cutting recesses can be rolled with particularly good thread quality.

Suitably, the optionally existing screw head of the screw is upset before the thread rolling process. The screw according to the invention can also have engagement points of drivers on the shank, except for the cutting recess or the cutting recesses, which are arranged on the rolling jaw according to the invention. These However, engagement points are not intended, in particular because of their geometry, to widen a borehole as a rule.

The invention will be explained in more detail below with reference to preferred embodiments, which are shown schematically in the accompanying figures, wherein individual features of the embodiments shown below within the scope of the invention can be implemented individually or in any combination. In the figures show schematically:

Figure 1: an embodiment of an inventive concrete screw in

Side view;

Figure 2: the screw of Figure 1 in cross-sectional view;

Figure 3: the screw of Figure 1 in perspective view;

Figures 4 to 6: a workpiece in various successive stages during the manufacturing sequence of a first embodiment of a method according to the invention for producing a concrete screw;

FIG. 7 is a perspective view of the rolling die arrangement according to the invention from FIG. 6, wherein the screw head is not shown for the sake of clarity; and

FIG. 8 shows the rolling-jaw arrangement from FIG. 6 in a side view, wherein again the screw head is not shown for the sake of clarity.

An embodiment of a concrete screw according to the invention is shown in FIGS. 1 to 3. The screw has a cylindrical shank 31, at one end of which a screw head 39 is formed, which has a polygonal structure designed as an external hexagon for positively rotationally fixed coupling to a setting tool, for example an impact wrench. At its opposite end, ie in the region of the tip, which is first introduced into the borehole, the shank of the concrete screw has a substantially flat end face 43.

On the lateral surface of the shaft 31, a thread 33 is formed which has a helical thread turn 13 and a spiral thread root 14 delimited by the thread turn 13. Under the thread root 14, in particular the surface Chen region of the shaft 31 are understood, which is limited in the longitudinal direction of the shaft 31 viewed on two axially opposite sides of the threaded coil 13.

The beginning of the thread turn 13 is in the region of the tip of the concrete screw, that is in the tip region 41. In the region of the threaded end, ie on the opposite side of the thread 33 of the tip portion 41 a Zusatzgewindewendel 15 is formed centrally in the thread root 14. While the thread helix 13 preferably has at least four turns, the auxiliary helix 15 comprises only about one turn. The threaded coil 13 preferably begins directly on the end face 43, but can also be spaced a distance from this. The concrete screw can be screwed self-tapping into a borehole in a concrete structure in the direction indicated in Figures 2 and 3 with an arrow screwing 81 of the thread 33.

In the tip region 41, the concrete screw on a plurality of cutting recesses, in the illustrated embodiment six, which are introduced into the lateral surface of the shaft 31, wherein one of the six cutting recesses is exemplified by the reference numeral 36. The cutting recesses have at their edges at the transition to the cylindrical lateral surface of the shaft 31 cutting edges, which can serve to widen a not ideal cylindrical and / or too narrow hole when screwing the screw. The resulting concrete flour can be at least partially absorbed and / or carried away by the cutting recesses. In the illustrated embodiment, the cutting recesses extend parallel to each other and parallel to the longitudinal direction of the shaft 31. In principle, the cutting recesses could also be arranged at an angle to each other and / or to the longitudinal axis.

1 and 3, the cutting recess 36 is formed in two parts with two partial regions 36 'and 36 ".The two partial regions 36' and 36" of the cutting recess 36 are aligned with one another, ie the first partial region 36 'lies in the extension of the second portion 36 ", wherein the two portions 36 ', 36" are separated by the thread turn 13. The first portion 36 'is completely within the thread root 14, whereas the second portion 36 "outside the thread root 14, that is in a range that is so close to the tip of the screw that he viewed in the longitudinal direction of the shaft 31 only on one side is bounded by the thread turn 13. As shown particularly in FIG. 3, the cutting recess 36 extends at its second portion 36 "as far as the end face 43 of the shaft 31 so that the cutting recess 36 is open towards the end face 43. The thread turn 13 is completely continuous, that is none of the cutting recesses interrupts the thread turn 13.

As FIG. 2 shows, the cutting recess 36 in the shell of the shaft 31 can be formed asymmetrically in the cross section of the shaft 31. In particular, that edge 18, which travels in the direction defined by the threaded coil 13 and marked in Figures 1 and 3 with an arrow screwing 81, be made steeper than the opposite leading edge 19. Thus, that edge 18, when screwing the finished screw acts against the surrounding concrete to develop a good cutting action, with a large access surface is given in the cutting recess 36 due to the flat design of the second edge 19, which may allow a particularly reliable material transport of concrete flour into the cutting recess 36. The screwing-in direction 81 of the threaded helix 13 or of the thread 33, which is indicated by an arrow in FIGS. 1 and 3, may in particular be directed counter to the workpiece rolling direction of rotation 84 during thread rolling, which is indicated by an arrow in FIGS. 6 and 7.

FIGS. 4 to 8 illustrate an exemplary embodiment of a method for producing a screw according to the invention, wherein FIGS. 4 to 6 show a sequence of stages starting from an unprocessed piece of wire.

As FIG. 4 shows, the method begins with the provision of a straight piece of metal wire as the workpiece 11.

In the following method step, which may comprise a plurality of individual forming steps, the screw head 39 with an external hexagonal structure is upset at one end of the workpiece 11, thereby obtaining the preliminary product shown in FIG.

Then, the workpiece 11, as shown in FIGS. 6 to 8, is introduced between two rolling dies 61 and 62 according to the invention, which are designed in particular as flat-rolled jaws. In the illustrated embodiment, the first rolling jaw 61 is stationary, whereas the second rolling jaw 62 is linearly moved in the direction of movement 86. As a result of the movement of the rolling jaws 61 and 62 relative to one another, the workpiece 11 is rotated in the workpiece rolling direction of rotation 84 and moved relative to the second rolling jaw 62 in the working direction 88 of the second rolling jaw 62. An analogous movement is given relative to the first rolling jaw 61. In the rolling process shown in FIGS. 6 to 8, on the one hand, the thread 33 with the threaded helix 13 is rolled onto the lateral surface of the shank 31 and, on the other hand, the cutting recesses 36 are rolled into the lateral surface of the shank 31. As the final product, the screw of Figures 1 to 3 is obtained.

As shown in FIGS. 6 to 8, the rolling jaw 62 according to the invention has, at its working surface parallel to the plane of the drawing, a multiplicity of mutually parallel grooves 64 which serve to form the threaded helix 13 and which, as such, form a counter-shape of the thread 33 exhibit. In addition, rolling jaw 62 has a plurality of projections 66 which press the cutting recesses 36 into the shaft 31.

The rolling jaw 62 consists of a main part 68 and a replaceable plate 69 which is detachably connected by screws to the main part 68. The working surface of the rolling jaw 62 extends over both the main part 68 and the exchangeable plate 69. All projections 66 for the cutting recesses 36, but at least a subset thereof, are preferably arranged on the exchangeable plate 69. The grooves 64 for the thread 33 extend both on the main part 68 and on the exchangeable plate 69th

The projections 66 for the cutting recesses 36 extend transversely to the working direction 88 considered offset to the grooves 64 and do not interrupt the course of the grooves 64. Each of the cutting recesses 36 is not formed by a projection 66 alone, but gradually by a plurality of successively arranged in the direction of 88 projections 66, that is, for forming a cutting recess 36, a portion of the shaft 31 of a plurality of projections 66 acted upon successively. The totality of all the protrusions 66 that transform one of the cutting recesses 36 form a protrusion set, wherein two different protrusion sets 67 'and 67 "are shown by way of example for two different cutting recesses 36. It is particularly preferred that the height of the protrusions 66 of a Projecting set 67 at least partially along the working direction 88 increases, so that the corresponding cutting recess is formed successively deeper.

The first rolling jaw 61 is formed analogously to the second rolling jaw 62 with grooves and projections, possibly also with projection sets, main part and / or exchangeable plate.

Claims

1. Concrete screw with

a shaft (31) and

a thread (33) arranged on the shank (31) with a thread turn (13) and a thread root (14),

characterized,

that in the tip region (41) of the shaft (31) in the shank (31) at least one cutting recess (36) is provided for expanding a borehole, which extends at least partially within the thread root (14), without interrupting the threaded helix (13).

2. concrete screw according to claim 1,

characterized,

the cutting recess (36) is interrupted at least once by the thread turn (13) of the thread (33).

3. Concrete screw according to one of the preceding claims,

characterized,

the cutting recess (36) extends in regions outside the thread root (14),

wherein preferably the cutting recess (36) to the end face (43) of the shaft (31) is open.

4. Concrete screw according to one of the preceding claims,

characterized,

the cutting recess (36) runs at least in regions within the first turn of the thread base (14) starting from the thread beginning.

5. concrete screw according to one of the preceding claims,

characterized,

the depth of the cutting recess (36) is at least 0.05 times, preferably at least 0.1 times, the diameter of the shank (31).

6. Concrete screw according to one of the preceding claims,

characterized,

that the cutting recess (36) in the cross section of the shaft (31) viewed asymmetrical, viewed in the screwing (81) of the threaded helix (13) leading edge (19) of the cutting recess (36) in the cross section of the shaft (31) viewed in relation to the The lateral surface of the shaft (31) extends as an edge trailing in the screwing direction (18) of the cutting recess (36).

7. concrete screw according to one of the preceding claims,

characterized,

in that at least one further cutting recess (36) is provided in the shank (31) which is located in the continuation of the thread helix (13) for free cutting of the thread helix (13).

8. concrete screw according to one of the preceding claims,

characterized,

that in the tip region (41) of the shaft (31) in the shank (31) a plurality of cutting recesses (36) are provided for expanding the borehole, which extend at least partially within the thread root (14), without interrupting the threaded helix (13).

9. Concrete screw according to one of the preceding claims,

characterized,

in that at least one additional threaded spiral (15) is provided which extends at least partially in the thread root (14), in particular on the side of the thread (33) opposite the tip region (41).

10. Concrete screw according to one of the preceding claims,

characterized,

in that it has a worm head (39) widened in relation to the shank (31).

11. rolling jaw (61, 62) for producing a concrete screw, preferably a concrete screw according to one of the preceding claims, with

a plurality of grooves (64) for rolling a thread (33), characterized,

in that the rolling jaw (61, 62) has at least one projection (66) for rolling a cutting recess (36) which does not interrupt the grooves (64) for rolling the thread (33).

12. rolling die (61, 62) according to claim 11,

characterized,

in that the rolling jaw (61, 62) has at least one projection set (67) consisting of a plurality of projections (66) for multi-stage rolling of one and the same cutting recess.

13. rolling die (61, 62) according to claim 12,

characterized,

the height of the projections (66) of the projection set (67) increases at least in regions in the working direction (88) of the rolling jaw (62).

14. A method for producing a concrete screw according to one of claims 1 to 10 in which both the thread helix (13) and the cutting recess (36) are formed in the same thread rolling process, preferably by means of a rolling die (61, 62) according to any one of claims 11 to 13th

15. The method according to claim 14,

characterized,

in that the cutting recess (36) is formed by a plurality of projections (66) which are arranged one behind the other on one and the same rolling die (61, 62).