Fastening element and method for fastening

Description

[0001] The invention relates to a fastening element comprising a plastic dowel sleeve and an impact element for driving into the dowel sleeve, wherein the impact element expands the dowel sleeve at least partially in a radial direction when the impact element is driven into the dowel sleeve. The invention also relates to a method for fastening a workpiece to an object.

[0002] EP 1 518 056 B1 discloses a plastic expansion anchor for expansion with an expansion nail.

[0003] The invention is intended to improve a fastening element with a plastic dowel sleeve and an impact element for driving into the dowel sleeve as well as a method for fastening a workpiece to an object.

[0004] According to the invention, a fastening element is provided for this purpose with a dowel sleeve made of plastic and an impact element for driving into the dowel sleeve, in which the impact element spreads the dowel sleeve at least partially in the radial direction when the impact element is driven into the dowel sleeve, wherein the impact element has a shaft and a head, wherein the shaft is provided at least partially with a thread formation and the head with an external drive formation, wherein the head has an impact section which extends from the external drive formation to the free end of the head and wherein the impact section has a cylindrical shape and a smaller outer diameter than the external drive formation.

[0005] The fastening element according to the invention, similar to a knock-in dowel or nail dowel, is intended exclusively for the temporary fastening of workpieces with low holding force. By simply driving in the impact element, the workpiece can be quickly pre-fixed. Second fastening means, intended for the final fastening, can then be arranged after the pre-fixing. For example, the pre-fixing by means of the fastening element according to the invention can also serve to hold the workpiece until an adhesive hardens or dries. The removal of the fastening element according to the invention after the final fastening of the workpiece to the object is then very simple via the external drive formation, for example, an external hexagon.The provision of a separate impact section makes it possible to drive the fastening element according to the invention even with high impact force without fear of damaging the external drive structure. The impact section may be deformed during driving, increasing its outer diameter.

[0006] However, since the outer diameter of the impact section is smaller than the external drive formation, even with a certain deformation, the outer diameter of the impact section remains smaller than the outer diameter of the drive formation, so that the fastening element can be easily removed by unscrewing the impact element. For example, the outer diameter of the impact section is smaller than an imaginary circle of the external drive formation inscribed in the outer contour of the external drive formation, in particular 10% to 25% smaller than the inscribed circle of the external drive formation. The impact element usually has a shank in the form of a nail screw with a buttress thread. The dowel sleeve can also be matched to a nail screw. The fastening element according to the invention enables very rapid pre-fixing of a workpiece.For example, when attaching a railing to a concrete floor, the railing can be pre-fixed very quickly and with just a few hammer blows. The final attachment is then achieved by drilling holes through a floor section of the railing into the concrete floor and then securing the railing using suitable fastening anchors, such as chemical anchors that are glued into the concrete and suitable screws, or even frame anchors. After the final attachment of the railing, the fastening elements according to the invention are then removed again and, for example, second fastening elements for the final attachment are screwed into the through holes in the floor section of the railing from which the fastening elements according to the invention are unscrewed.Of course, essentially any workpiece can be pre-fixed to any object using the fastening element according to the invention, for example railings to buildings, window frames to window reveals, door frames to masonry, or the like. What is important is that the fastening elements according to the invention enable extremely rapid pre-fixing with just a few hammer blows, while the fastening force or holding force exerted by the fastening elements according to the invention is significantly smaller than the fastening force or holding force required for final fastening. For example, a railing must be fastened so securely that it does not break even if a person throws themselves against the railing. With the fastening element according to the invention, such a high holding force is not required, since the fastening element according to the invention is only intended for pre-fixing the railing.

[0007] In a further development of the invention, the fastening element has a contact section between the head and the shaft of the impact element, wherein an outer diameter of the contact section is at least three times as large as an outer diameter of the shaft of the impact element.

[0008] In this way, the contact section can be used to reliably temporarily fix a workpiece to an object. This is possible, for example, even if a through hole in the workpiece is significantly larger than the outer diameter of the fastener's shank. The contact section can then still exert a preload force on the workpiece, which then presses the workpiece against the object for preliminary fixation.

[0009] In a further development of the invention, the contact section is designed in the form of a washer threaded onto the shaft.

[0010] In this way, the system section can be implemented in a very simple manner.

[0011] In a further development of the invention, a through-hole in the washer through which the shaft extends has a diameter that is at least 10% to 100% larger than an outer diameter of the shaft.

[0012] The washer thus surrounds the shaft with a comparatively large amount of play. This allows the workpiece to still be aligned relative to the object, even after the impact element of the fastening element according to the invention has already been driven in. The head of the impact element must, of course, have a larger diameter than the through hole in the washer. The preload force applied to the workpiece by the fastening element according to the invention during pre-fixing is still so low that the workpiece can be aligned relative to the object, for example, with lateral hammer blows.

[0013] In a further development of the invention, the contact section is formed integrally with the impact element.

[0014] In a further development of the invention, the contact section has at least one groove-like formation running perpendicular to the shaft.

[0015] Using the fastening element according to the invention, structural steel bars or other cylindrical workpieces can be pre-fixed very easily and securely. For example, structural steel bars or reinforcement structures made of structural steel bars, so-called rebars, can be pre-fixed very easily using the fastening elements according to the invention before these structural steel bars are then encased in liquid concrete.

[0016] In a further development of the invention, the contact section has an anti-slip underside facing away from the head.

[0017] For example, a rubber coating or a disc made of elastic, rubber-like material is provided. For example, the support section can also have a rough underside, an underside with protruding projections or points. The anti-slip underside serves to reliably pre-fix a workpiece to an object. The anti-slip underside is advantageously matched to the material of the workpiece to be pre-fixed. An underside of the support section is referred to as anti-slip if it creates a higher coefficient of friction between the underside of the support section and the top side of the workpiece compared to a smooth metal underside of the support section.

[0018] The problem underlying the invention is also solved by a method for fastening a workpiece to an object, which method comprises the following steps: drilling a hole in the object and drilling a through-hole in the workpiece, inserting a fastening element according to the invention into the through-hole and the drilled hole, driving the driving element into the dowel sleeve and thereby temporarily fixing the workpiece to the object, wherein a first holding force with which the fastening element can be acted upon before failure is smaller than a second holding force with which a second fastening element, which is provided for a final fastening of the workpiece to the object, can be acted upon.

[0019] The fastening element according to the invention is thus intended exclusively for pre-fixing. This pre-fixing can be carried out easily and extremely quickly by simply inserting the fastening element and driving the driving element into the dowel sleeve. The holding force that the fastening element according to the invention can exert only needs to be large enough to pre-fix the workpiece so that the second fastening elements, which are intended for the final fastening, can then be attached. For example, the fastening elements according to the invention can also be used for pre-fixing the workpiece and are then removed again as soon as a material-to-material connection has been established between the workpiece and the object, for example by gluing, soldering, or welding.

[0020] In a further development of the invention, the first holding force is smaller than the second holding force by at least a factor of 5, in particular a factor of 10.

[0021] As explained, the fastening element according to the invention merely provides a pre-fixing effect. If necessary, the first holding force is so low that the workpiece can still be aligned relative to the object, for example, by lateral hammer blows. The pre-fixing effect is intended only to hold the workpiece in position so that the second fastening means can be applied and / or a material-to-material connection can be established.

[0022] In a further development of the invention, the setting of at least the second fastening element and / or the material-to-material connection of the workpiece and the object and thereby the final fixing of the workpiece to the object is provided.

[0023] In a further development of the invention, the removal of the fastening element is provided after setting at least the second fastening element and / or after the material-to-material connection.

[0024] Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. In the drawings: Fig. 1 shows a side view of a fastening element according to the invention according to a first embodiment, Fig. 2 shows a sectional view of a fastening element according to the invention according to a second embodiment, Fig. 3 shows a sectional sectional view of a fastening element according to the invention according to a third embodiment, and Fig. 4 shows several successive method steps when fastening a workpiece to an object with a fastening element according to the invention.

[0025] Fig. 1 shows a fastening element 10 according to the invention with a dowel sleeve 12 made of plastic and an impact element 14. The impact element 14 expands the dowel sleeve 12 in sections in the radial direction when the impact element 14 is driven into the dowel sleeve 12. In particular, the expansion area 16 of the dowel sleeve 12 is expanded in the radial direction and thereby anchored in an object, in particular in a drilled hole of the object, when the impact element 14 is driven into the dowel sleeve 12, in Fig. 1 i.e. moved to the right into the dowel sleeve 12.

[0026] The driving element 14 has a head 18 and a shaft 20. The shaft 20 is provided with a buttress thread 22 in sections. The buttress thread 22 is designed such that it can be driven into the dowel sleeve 12 to the right. However, the buttress thread 22 then offers greater resistance against the driving element 14 being pulled out of the dowel sleeve to the left. The driving element 14 can also be screwed into and out of the dowel sleeve 12 using the buttress thread 22. The driving element 14 can also be unscrewed from the dowel sleeve 12 again after driving in.

[0027] The head 18 has an external drive formation 24 and an impact section 26. In the illustrated embodiment, the external drive formation 24 is designed as an external hexagon. The impact section 26 has a cylindrical shape, in the illustrated embodiment a circular cylindrical shape. The impact section 26 adjoins the external drive formation 24 in the direction of the free end of the head 18, in Fig. 1 the impact section 26 is therefore arranged to the left of the external drive formation 24.

[0028] A contact section 28 is arranged between the head 18 and the shaft 20 of the impact element 14. In the illustrated embodiment, the contact section 28 is disc-shaped and formed integrally with the head 18 and the shaft 14. The contact section 28 has a significantly larger outer diameter than the shaft 20. Specifically, the outer diameter of the contact section 28 is at least three times as large as the outer diameter of the shaft 20. In the illustrated embodiment, the outer diameter of the contact section 28 is approximately five times as large as the outer diameter of the shaft 20. The contact section 28 exerts a preload force on a workpiece for pre-fixing.

[0029] To fasten a workpiece to an object, first a through-hole is formed in the workpiece and a drilled hole in the object. The drilled hole in the object, for example in a concrete floor, is usually designed as a blind hole. The fastening element 10 is then inserted through the through-hole in the workpiece and sectionally into the drilled hole in the object. This can be done so far that the Fig. 1 left end of the dowel sleeve 12 rests against the top side of the workpiece and the expansion area 16 is completely arranged within the object. Pre-fixing of the workpiece to the object, for example to a concrete floor, can then be carried out very easily by driving the impact element 14 into the dowel sleeve 12 with a hammer until the contact section 28 rests on the workpiece. With the correct dimensioning of the length of the impact element 14, the thickness of the workpiece and the length of the dowel sleeve 12, the impact element 14 then spreads open the expansion area 16 of the dowel sleeve 12 so that the fastening element is anchored in the drilled hole in the object by frictional engagement. The workpiece is then also pre-fixed to the object.

[0030] The holding force of the fastening element 10 according to the invention is significantly lower than the holding force required for final fastening of the workpiece to the object. For example, the holding force that can be applied with the fastening element 10 according to the invention is a factor of 5, in particular a factor of 10, or a factor between 5 and 10 lower than the holding force of a second fastening element, with which final fixation is then carried out. The purpose of the fastening element according to the invention is the pre-fixation of the workpiece to the object in order to be able to easily place the second fastening elements in exactly the desired position or, for example, to be able to wait for an adhesive between the workpiece and the object to harden without the workpiece having to be held in place the entire time.For example, the fastening element 10 according to the invention can also be provided to fix the workpiece to the object in order to then be able to solder or weld the workpiece to the object.

[0031] When the impact element 14 is driven into the dowel sleeve 12, the impacts are applied to the impact section 26. The impact section 26 inevitably deforms and increases its outer diameter. The impact section 26 serves as a sacrificial section. The outer diameter of the impact section 26 is smaller than the outer diameter of the external drive formation 24. Even if the impact section 26 deforms so that its outer diameter becomes larger, this does not impair the ability to unscrew the impact element 14 via the external drive formation 24. In particular, a screw socket can be inserted over the external drive formation 24 so that the impact element 14 can be unscrewed very quickly, for example using a cordless screwdriver or the like. Advantageously, the outer diameter of the impact section is 10% to 25% smaller than a circle inscribed in the outer contour of the external drive formation 24.In such a case, there is no risk that the impact section 26 will increase its diameter so much when driving in the impact element 14 that it projects beyond the outer contour of the external drive formation 24.

[0032] When unscrewing the impact element 14 from the dowel sleeve 12, the prestressing force with which the expansion section 16 is pressed radially outward against the inner wall of the drilled hole in the object is significantly reduced, and in particular reduced to a value close to zero. The dowel sleeve 12 can thus be very easily pulled out of the drilled hole and also pulled through the through hole in the workpiece. This can be done, for example, by applying a force to the contact section 28 in Fig. 1 is pulled to the left. Within the scope of the invention, it is entirely conceivable to use a special tool that engages behind the contact section in order to be able to pull the fastening element out of the workpiece and the object particularly quickly.

[0033] While the workpiece is pre-fixed to the object with the fastening element 10 according to the invention, second fastening elements are inserted to finally fasten the workpiece to the object with the prescribed holding force. After removing the fastening element 10 according to the invention, a second fastening element can then be inserted and secured, for example, into the existing through-hole and into the existing drilled hole.

[0034] The advantage of the fastening element 10 according to the invention lies in the fact that pre-fixing can be achieved very quickly by simply inserting and hammering in. The holding force of the pre-fixing only needs to be large enough to allow the final fixation of the workpiece to the object, for example, by drilling holes and using second fastening elements or by firmly bonding the workpiece to the object.

[0035] Fig. 2 shows a partial sectional view of a fastening element 30 according to a further embodiment of the invention. The dowel sleeve 12 is in Fig. 2 Not shown for the sake of simplicity. The fastening element 30 is intended to pre-fix a structural steel structure 32 to a concrete floor 36.

[0036] The impact element 34 of the fastening element 30 differs from the impact element 14 of the embodiment of the Fig. 1 only by providing a differently designed contact section 38. The impact section 26, the external drive formation 24 and the shaft 20 of the impact element 34 are designed exactly the same as the impact element 14 of the Fig. 1 and are therefore not explained again.

[0037] Annex section 38 is in Fig. 2 shown only schematically and has two groove-shaped recesses 40. The groove-shaped recesses 40 are each intended to receive and fix a section of the structural steel structure 32.

[0038] After pre-fixing the structural steel structure 32 to the concrete floor 36 with the fastening element 30 according to the invention, liquid concrete is applied to the concrete floor 36. After curing, the structural steel structure 32 is thus securely fixed. In this case, the fastening element 30 according to the invention remains in the poured concrete.

[0039] The representation of the Fig. 3 shows a fastening element 50 according to the invention according to a further embodiment in a sectional view. The dowel sleeve 12 is not shown for the sake of simplicity. An impact element 54 has a head with an impact section 26 and an external drive section 24, which are of the same design as the impact element 14 of Fig. 1 and therefore need not be explained again. The shaft 20 of the impact element 54 is also designed in the same way as the impact element 14 of the Fig. 1 The dowel sleeve not shown also corresponds to the dowel sleeve 12 of the Fig. 1 .

[0040] A contact section 58 is designed as a washer that is threaded onto the shaft 20. An outer diameter of the head on the underside of the external drive formation 24 is larger than a through-hole 60 of the washer that forms the contact section 58. An inner diameter of the through-hole 60 is significantly larger, in particular 1.5 times to 3 times, especially 2 times, as large as the outer diameter of the shaft 20. The contact section 58 can thus be moved relative to the shaft. Even when the impact element 54 has already been driven into the dowel sleeve 12 and a preload force is thereby exerted on the workpiece by the underside of the contact section 58, the workpiece can still be moved relative to the object, for example, by light hammer blows laterally against the workpiece. The contact section 58 can then be displaced together with the workpiece relative to the shaft 20.

[0041] One in Fig. 3 The underside of the contact section 58 facing the workpiece (not shown) is provided with an anti-slip design. This anti-slip design is in the form of jagged projections 62. The jagged projections 62 dig slightly into the top side of the workpiece, which may be made of wood, for example. The contact section 58 is thereby fixed relative to the workpiece. When aligning the workpiece relative to the object, the contact section 58 can then be moved together with the workpiece relative to the shaft 20 of the impact element 54 and thus relative to the object without any pre-fixing being completely removed, since a pre-tensioning force is still exerted on the workpiece by means of the fastening element 50 according to the invention.

[0042] Fig. 4 shows several steps in fastening a workpiece 70 to an object 72 with a fastening element 80 according to another embodiment of the invention. The workpiece 70 is designed, for example, as a railing or handrail section. The object 72 is a section of masonry, for example, a building wall.

[0043] In step a, a through hole is made in the workpiece 70 and after penetrating the workpiece 70, a blind hole is made in the object 72.

[0044] In step b, after cleaning the drilled hole and the through-hole, the fastening element 80 according to the invention is inserted into the through-hole in the workpiece 70 and the drilled hole in the object 72. This is symbolized by two arrows above the dowel sleeve 82 and above the impact element 84.

[0045] In step c, the dowel sleeve 82 has been inserted into the workpiece 70 and the object 72 to such an extent that a head of the dowel sleeve 82 rests on an upper side of the workpiece 70 facing away from the object 72. The expansion section of the dowel sleeve 82 lies completely within the object 72.

[0046] In this state, the impact element 84 is now driven into the dowel sleeve 82 with a few hammer blows on the impact section 26. The impact or driving of the impact element 84 continues until the state in step d is reached. A contact section 88 of the fastening element 80 now rests on the upper side of the workpiece 70, which faces away from the object 72. The impact element 84 has completely penetrated the dowel sleeve 82 and thereby spread it radially outward in the area in which the dowel sleeve 82 is arranged in the drilled hole in the object 72. The contact section 88 pre-tensions the workpiece 70 against the object 72.

[0047] The holding force exerted on the workpiece 70 by means of the fastening element 80 is substantially smaller than the holding force with which the workpiece 70 must be finally fastened to the object 72. For example, the first holding force exerted by the fastening element 80 is between a factor of 5 and a factor of 10 smaller than the second holding force with which the workpiece 70 must be held to the object 72 in the finally assembled state. The second holding force is a holding force that is applied, for example, by a single second fastening element.

[0048] The contact section 88 is designed as a sheet metal strip with a slight angle at its free ends. The contact section 88 can therefore be slightly resilient to reliably pre-fix the workpiece 70 to the object 72.

[0049] After the workpiece 70 has been pre-fixed to the object 72 in state d, the object 70 is finally fixed to the object 72. Finally, the fastening element 80 can be removed. This is done by unscrewing the impact element 84 from the dowel sleeve 82 using the external drive formation 24 at least until the impact element is completely or almost completely removed from the drilled hole in the object 72 and thus from the expansion area of ​​the dowel sleeve 82. As a result, the expansion section of the dowel sleeve 82 is no longer pushed radially outwards and the impact element 84 can be easily pulled out together with the dowel sleeve 82 from the drilled hole in the object 72 and the through-opening in the workpiece 70, in the illustration of the Fig. 4 to the left.

[0050] A second fastening element, for example a plastic dowel with a screw, can then be inserted into the drilled hole in the object 72 and the through opening in the workpiece 70.

[0051] The fastening element according to the invention and the method according to the invention enable a very simple and, above all, rapid pre-fixing of a workpiece to an object. The workpiece can thus be held in the intended final position on the object, allowing for the final fastening or fixing of the workpiece to the object. The final fixing can be achieved, for example, by second fastening elements, but also by means of a material bond, for example, by gluing, soldering, or welding.

Claims

1. Fastening element (10; 30; 50; 80) having a dowel sleeve (12) of plastics material, and an impaction element (14; 34; 54; 84) for driving into the dowel sleeve (12), wherein the impaction element expands the dowel sleeve (12) at least in portions in the radial direction when driving the impaction element into the dowel sleeve (12), wherein the impaction element (14; 34; 54; 84) has a shank (20) and a head (18), wherein the shank (20) is provided at least in portions with a thread formation and the head (18) is provided with an external drive configuration (24), wherein the head (18) has an impact portion (26) which, proceeding from the external drive configuration (24), extends to the free end of the head (18), and wherein the impact portion (26) has a cylindrical shape and a smaller external diameter than the external drive configuration (24).

2. Fastening element according to Claim 1, <b>characterized by a contact portion (28; 38; 58; 88) between the head (18) and the shank (20) of the impaction element (14; 34; 54; 84), wherein an external diameter of the contact portion (28; 38; 58; 88) is at least three times larger than an external diameter of the shank (20) of the impaction element (14; 34; 54; 84).

3. Fastening element according to Claim 2, characterized in that the contact portion is designed in the form of washer threaded onto the shank (20).

4. Fastening element according to Claim 3, characterized in that a passage opening (60) in the washer, through which the shank (20) extends, has a diameter that is at least 10% to 100% larger than an external diameter of the shank (20).

5. Fastening element according to Claim 2, characterized in that the contact portion (28) is formed integrally with the impaction element (14).

6. Fastening element according to at least one of Claims 2 to 5, characterized in that the contact portion (38) has at least one channel-type moulding (40) which extends perpendicularly to the shank (20).

7. Fastening element according to one of Claims 2 to 6, characterized in that the contact portion (58) has a non-slip lower side which faces away from the head.

8. Method for fastening a workpiece (70) to an object (72), comprising the following method steps: incorporating a drilled hole into the object (72) and incorporating a through hole into the workpiece (70); inserting a fastening element (80) according to one of the preceding claims into the through hole and the drilled hole; driving the impaction element (84) into the dowel sleeve (12) and thereby temporarily fixing the workpiece (70) to the object (72); wherein a first holding force with which the fastening element (80) can be impinged before failure is smaller than a second holding force with which a second fastening element, which is provided for a final fastening of the workpiece (70) to the object (72), can be impinged.

9. Method according to Claim 8, characterized in that the first holding force is smaller than the second holding force by at least a factor of 5, in particular a factor of 10, in particular by a factor between 5 and 10.

10. Method according to Claim 8 or 9, characterized by setting the second fastening element, or a plurality of second fastening elements, and / or by connecting the workpiece (70) and the object (72) in a materially integral manner / by a substance-to-substance bond, and thereby finally fixing the workpiece (70) to the object (72).

11. Method according to Claim 8, 9 or 10, characterized by removing the fastening element (80) after setting the second fastening element, or the plurality of second fastening elements, and / or after materially integral connecting / substance-to-substance bonding.