Method for setting a screw

Abstract

A method for setting a screw, which has an external thread in a front region and a drive in a rear region for introducing a torque into the screw, in a drilled hole in a substrate of a mineral material includes producing an internal thread in the drilled hole by a threaded drill provided with a cutting thread and then introducing the screw into the drilled hole and in so doing the external thread of the screw is screwed into the internal thread, produced by the threaded drill, in the drilled hole. The external diameter of the cutting thread of the threaded drill is smaller than the external diameter of the external thread of the screw.

Claims

1. A method for setting a screw in a drilled hole in a concrete substrate, wherein the screw has an external thread in a front region and a drive in a rear region, comprising the steps of: producing an internal thread in the drilled hole in the concrete substrate by a threaded drill provided with a cutting thread; and then following the producing, inserting the screw into the drilled hole in the concrete substrate and screwing the external thread of the screw into the internal thread in the drilled hole in the concrete substrate, which internal thread has been produced by the threaded drill; wherein an external diameter of the cutting thread of the threaded drill is smaller than an external diameter of the external thread of the screw.

2. The method according to claim 1, wherein the external diameter of the cutting thread of the threaded drill is 0.85 to 0.92 times the external diameter of the external thread of the screw.

3. The method according to claim 1, wherein a thread pitch of the cutting thread of the threaded drill deviates by less than 3% of a thread pitch of the external thread of the screw.

4. The method according to claim 1, wherein a core diameter of the cutting thread of the threaded drill deviates by less than 3% of a core diameter of the external thread of the screw.

5. The method according to claim 1, wherein a thread length of the cutting thread of the threaded drill deviates by less than 3% of a thread length of the external thread of the screw.

6. The method according to claim 1, wherein during the screwing, an add-on part is simultaneously set on the concrete substrate.

7. The method according to claim 1, wherein the drive is a screw head.

8. The method according to claim 1, wherein the screwing of the external thread of the screw into the internal thread in the drilled hole in the concrete substrate radially expands the internal thread which produces loose concrete substrate particles that fall into the drilled hole in the concrete substrate and compress a shaft of the screw.

9. The method according to claim 1, wherein there is no interim step between the step of producing the internal thread in the drilled hole in the concrete substrate by the threaded drill and the steps of inserting the screw into the drilled hole in the concrete substrate and screwing the external thread of the screw into the internal thread in the drilled hole in the concrete substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 to 4 are schematic images of sequential stages in carrying out the method according to the invention;

(2) FIG. 5 is a detailed view of the threaded drill, which is used in the method according to FIGS. 1 to 4, as seen from the side;

(3) FIG. 6 is a detailed view of the screw, which is used in the method according to FIGS. 1 to 4, as seen from the side; and

(4) FIG. 7 is a schematic view of a package according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIGS. 1 to 4 depict various stages in carrying out a method according to the invention.

(6) Initially in the method, as shown in FIG. 1, a preferably at least almost cylindrical drilled hole 2 is provided in a substrate 1 of a mineral material, particularly concrete.

(7) Then, as shown in FIG. 2, a threaded drill 10 is inserted into drilled hole 2. Threaded drill 10 has a preferably at least almost cylindrical shaft 15 as well as a spiral-shaped cutting thread 16, which is arranged on shaft 15. In a rear region, threaded drill 10 has a drive 11, depicted for example purposes as a head, particularly a hexagonal head, for introducing a torque in shaft 15. Cutting thread 16 has an external diameter da.sub.S (cf. FIG. 5), which is greater than the interior diameter of drilled hole 2. Therefore, cutting thread 16 cuts its way into substrate 1 surrounding drilled hole 2 and produces an internal thread 19 in drilled hole 2. To screw in threaded drill 10 into drilled hole 2 in a particularly easy manner, core diameter dk.sub.S of cutting thread 16 of threaded drill 10 (cf. FIG. 5) may preferably be smaller than the internal diameter of drilled hole 2.

(8) In the next step, as shown in FIG. 3, threaded drill 10 is screwed back out of the drilled hole by turning in the opposite direction. Internal thread 19 is thereby left in drilled hole 2.

(9) Then, as shown in FIG. 4, an add-on part 9 is arranged in front of drilled hole 2 and a screw 20 is inserted through a recess in add-on part 9 into drilled hole 2. Screw 20 has a preferably at least almost cylindrical shaft 25 as well as a spiral-shaped external thread 26, which is arranged on shaft 25. In a rear region, screw 20 has a drive 21 depicted as a head, particularly a hexagonal head, for introducing a torque in shaft 25 and for the form-fitting holding of add-on part 9.

(10) External thread 26 of screw 20 has an external diameter da (cf. FIG. 6), which is larger than external diameter da.sub.S of cutting thread 16, and which is thus larger than the external diameter of internal thread 19 produced by cutting thread 16 in drilled hole 2. Consequently, internal thread 19 is radially expanded somewhat when screwing in screw 20. Loose substrate particles hereby fall into drilled hole 2, which can ensure a compression of shaft 25 of the screw and thus a radial support of drilled hole 2, whereby particularly good load values can be obtained for screw 20. For screwing in screw 20 in a particularly easy manner into drilled hole 2, core diameter dk of external thread 26 of screw 20 (cf. FIG. 6) may preferably be smaller than the internal diameter of drilled hole 2.

(11) As shown particularly in FIGS. 5 and 6, the following relationships apply to cutting thread 16 of threaded drill 10 and external thread 26 of screw 20, wherein the subscript S hereinafter indicates the parameter of threaded drill 10 in each case:

(12) For external diameter da.sub.S of cutting thread 16 of threaded drill 10 and external diameter da of external thread 26 of screw 20, respectively:
da.sub.S<da,
preferably da.sub.S<0.92da and/or da.sub.S>0.85da

(13) For thread length L.sub.S of cutting thread 16 of threaded drill 10 and thread length L of external thread 26 of screw 20 respectively, it is preferred that:
L.sub.S=L3%, preferably L.sub.S=L1%.

(14) For thread pitch P.sub.S of cutting thread 16 of threaded drill 10 and thread pitch P of external thread 26 of screw 20 respectively, it is preferred that:
P.sub.S=P3%, preferably P.sub.S=P1%.

(15) For core diameter dk.sub.S of cutting thread 16 of threaded drill 10 and core diameter dk of external thread 26 of screw 20 respectively, it is preferred that:
dk.sub.S=dk3%, preferably dk.sub.S=dk1%.

(16) FIG. 7 depicts a schematic view of a package 90 according to the invention, which contains a screw 20, a threaded drill 10, and operating instructions 100. Wherein operating instructions 100 describe a method according to the invention.