DE2229863C2 - Expansion anchor - Google Patents

Description

The invention relates to an expansion dowel with a screw bolt and expansion bodies in the form of Half-shells which enclose the screw bolts opposite one another and the adjacent ones Edges run obliquely to the longitudinal axis of the screw bolt form wedge surfaces, along which they are displaceable relative to each other, according to the main patent 1960 734 the half-shells in cross section approximately U-shaped and their legs through to form interlocking wedge surfaces Cutouts are designed in a sawtooth shape, the legs rest on the bolt shank and two opposite one another Edge areas of the legs are bent inward to hold it on the bolt.

In such an expansion dowel according to the main patent, the half-shells are loose on the screw bolts pushed so that for spreading at both ends of the screw bolt each an abutment for a half-shell in the form of a nut or a head must be provided. The mother must be on outer end of the screw bolt can be provided so that the screw bolt is tightened the dowel is pulled out of the drill hole a little and protrudes from the outside if the dowel is stuck, whereby this expansion anchor is not suitable for certain types of use.

The invention is based on the object of designing an expansion dowel of the type described at the outset in such a way that that it is easier to use and suitable for any type of fastening.

This is achieved according to the invention in that the inwardly curved edge regions of the Legs of a half-shell are threaded with the thread of the screw bolt is engaged.

ίο Through the thread on the inwardly bent This half-shell with the screw bolt remains in the edge areas of the half-shells even with a large spread in engagement, ^ o Uaß for the relative displacement of the two half-shells in the longitudinal direction the other

Haibschaie can rest on the head of the screw bolt. This allows the expansion anchor in one Borehole can be arranged so that only the head of the screw bolt protrudes on the outside. The Thread on the for example by punching

* o provided half-shells can, for example, be pressed in will.

From US Pat. No. 2,081,764, a Expansible dowels with half-shells are known which enclose a screw bolt opposite one another and the adjacent edges of which form wedge surfaces running at an angle to the longitudinal axis of the screw bolt, a half-shell being provided with an internal thread into which the thread tapers to a point The end of the screw bolt engages, but the thread has a different function in this embodiment. When tightening the dowel, this threaded half-shell is replaced by the type of a Wood screw formed screw bolts first from the wedge surface of the opposite half-shell lifted, whereupon they move by a sliding movement along the screw bolt due to the thread engagement is clamped between the borehole wall and the wedge surfaces of the other half-shell. Because of the required thread engagement on one half of the bolt circumference? is one of those Dowel no large expansion possible.

According to an expedient embodiment, in a manner known per se, on two opposite one another Edge areas of the legs of the half-shells each formed clamping tongues, the two clamping tongues only one half-shell has a thread on the inside. To hold the Half-shells on the bolt shank only need these clamping tongues with a small cross-section so that it is bent inside and bent back again when the dowel is spread open.

In an advantageous embodiment, the screw bolt is at the end lying in the borehole provided with a nut and at the outer end with a head, the one resting on the nut Half-shell is provided with the thread. The nut serves as a backup that prevents movement the threaded half-shell prevented in the loosening direction if, for example, by a extreme tensile force on the screw bolt the thread engagement should be loosened.

An example embodiment according to the invention is shown below with reference to the drawing explained in more detail in the

F i g. 1 shows an expansion dowel designed according to the invention in a side view;

F i g. 2 shows in perspective one of the half-shells of the expansion anchor according to FIG. 1;

F i g. 3 shows the half-shell according to FIG. 2 in a longitudinal section;

F i g. 4 shows a sectional view along the line 1-1 in Fig. 1 a screw bolt with partially spread apart Half-shells;

F i g. 5 shows an end view of a screw bolt with the half-shell pushed on.

In Fig. 1, 1 is a screw bolt with a usual hexagon head 2 shown on the opposite two in terms of shape Identically designed half-shells 3 and 4 with a U-shaped cross-section arranged as an expanding body are, with the legs of these half-shells resting on the bolt shank, as shown in FIG. 4 and 5 show. For the formation of interlocking wedge surfaces 5 the legs are sawtooth-shaped through cutouts designed.

Damii. the half-shells 3, 4 during storage and also when inserting the dowel into a borehole are held on the bolt 1 is on dom approximately in the middle of the longitudinal dimension of a Half-shell lying section in the area of the protruding beyond the center line of the screw bolt At the end of a wedge surface a recess 6 is provided in the two legs, through the clamping screws 7 trained at opposite points wer-JtMi. These clamping tongues are bent slightly inwards to hold the half-shells on the bolt, as in Fig. 2 shows. The half-shells can therefore initially not in the radial direction are lifted from the bolt while they are displaceable in the axial direction. Because of the small cross-section of these clamping tongues 7 can, even if the half-shells are made of hard Material are made, when the dowel is spread open by the bolt shank without further ado will.

The clamping tongues 7 of the half-shell 4 lying on the inside in the borehole are on the inside with provided some turns 8 of a thread that engages with the thread on the bolt 1 stands. Like F i g. 3 shows, these threads 8 only extend over the ankle area of FIG Half-shell that rests on the bolt shaft before and during expansion. The opposite half-shell 3 has no thread, so that they are easily displaced in the axial direction of the screw bolt 1 can.

When inserting this dowel into a borehole, the two half-shells 3 and 4 are arranged in such a way that that their clamping tongues 7 lie against one another, so that the diameter of the dowel is approximately that of the borehole and the dowel can be easily inserted. The half-shells 3 and 4 arrive here the borehole wall to rest. The hexagon head 2 is rotated to expand the dowel. the Half-shells 3 and 4 can be due to the frictional engagement of their relatively large outer surfaces Do not turn on the wall of the borehole. Through the engagement of the threads 8 on the half-shell with the thread on the bolt shank, this is initially relative to the two half-shells postponed. As soon as the hexagonal head 2 or one arranged between this and the half-shell 3 Spacer sleeve 9 comes to rest on the end of the half-shell 3 lying on the outside in the borehole, this is moved together with the bolt shank relative to the half-shell 4, due to the wedge surfaces 5 an expansion takes place. As the spreading increases, the clamping tongues 7 so well bent outwards that they are approximately tangential to the bolt shaft. The thread engagement of the Half-shell 4 with the bolt shank is thus retained even with an extremely large spread.

The two half-shells are centered, i.e. H. in one passing through the axis of the screw bolt I. Spread open plane without the sliding surface on the wedge surfaces 5 being significantly reduced will. The sleeve formed by the spread half-shells 3 and 4 is given an approximately oval shape or elliptical cross-sectional shape, as shown in FIG. 4 is shown. This ensures that the dowel is secured against rotation as well as against any kind of alternating load.

In the event of a tensile force acting on the bolt head 2, the half-shell 4 is due to the engagement with the bolt shank further with the half-shell 3 verao tensioned, so that there is a considerable holding force of the anchor. As tests have shown, the holding force lies of the anchor not below the permissible value even if the screw bolt, for example is only tightened with 0.5 mkp, while -the maximum holding force with a torque of 3 mkp is achieved. This safety factor is especially important for the use of the anchor in construction, for example for the attachment of facade panels and the like. Of importance.

If the provided on the inside of the clamping tongues 7 of the half-shell 4 threads 8 for If a certain tightening torque should not suffice, the one inside the borehole can be used At the end 10 of the half-shell 4, further threads are provided on the inside of the two legs

will.

Preferably, a nut 11 is provided as a safety measure, which is located on the in the borehole End of the screw bolt 1 is screwed. When inserting the dowel, the circumferential surface lies this nut 11 with friction on the borehole wall, so that it does not come with the screw bolt 1 turns. As a result, it maintains its position near the end 10 of the half-shell even during the spreading 4 at. If there is a considerable tensile force on the bolt head 2, the threads 8 on the clamping tongues tear out, this nut 11 comes to rest firmly against the half-shell 4, thereby counteracting it the half-shell 3 is clamped so that tearing of the screw bolt 1 is prevented. When in this case a slight loosening of the system of the bolt head 2 on the one to be fastened If part should occur, the dowel can be tightened again, the nut turning at the same time 55 is prevented by the bracing with the half-shell 4.

The threads 8 on the clamping tongues 7 of the half-shell 4 can also be designed so that When tightening the dowel, they only serve to brace the hands 10 of the Hulb shell 4 with the nut 11, so that it cannot rotate with it, even if there is little friction on the wall of the borehole. As soon as the Nut 11 rests firmly on the half-shell 4, need these threads 8 in the form of relatively short rips no longer match the thread on the bolt shank stay engaged.

If the half-shell 4 is now in the middle section on the clamping tongues 7 - as shown - with

a few threads 8 provided, the two half-shells 3 and 4 are opened when spreading The reason for the engagement of the clamping tongues 7 of one half-shell with the bolt shank with regard to their Longitudinal axes tilted relative to the longitudinal axis of the screw bolt, the end IO of the half-shell 4 and accordingly the end of the half-shell 3 lying on the outside in the borehole initially somewhat stronger from the Bolt shank is lifted off than the other end of the half-shells. For holding the dowel this is favorable because the outer end of the half-shell 3 claws into the borehole wall.

The half-shells are preferably designed to be identical with regard to their shape. You can punched out of a steel strip in an extremely simple manner, especially with a view to mass production and then bent accordingly. They can also be manufactured by injection molding, whereby the operation of deforming and the additional bending of the clamping tongues 7 and that Attaching the threads 8 is not necessary. The threads can be pressed in depending on the design of the anchor or also be incised.

To improve the frictional engagement of the half-shells 3.4 and the optionally provided nut 11 on the borehole wall can be on the corresponding Outer surfaces have radial approaches, for example in the form of axially extending Ribs and the like are provided.

The edges of the half-shells that form the wedge surfaces 5 can be left untreated after the punching process remain or be smoothed or sanded off. For certain uses it is too possible to manufacture the half-shells from a suitably strong plastic.

With a dowel according to the invention can with ίο a relatively small borehole diameter, the diameter corresponds to the nut 11 or the sleeve formed by the closely spaced half-shells, a very high spread can be achieved. The installation of the dowel is extremely easy and he is particularly suitable for certain applications in which only the bolt head 2 to the fastening part should protrude. For holding the half-shells on the bolt during the A nut 11 is not required for handling and storage, since the threads 8 are pulled off the half-shells from the bolt shank. Like F i g. 5 shows the legs are at the ends of the Wedge surfaces formed so long that they lias like the clamping tongues 7 over the center line of the screw protrude from bolt 1. The end sections can, as shown in FIG. 5 indicated at 12, slightly beveled will.

1 sheet of drawings

Claims (3)

Patent claims: 1. Expansion anchor with a screw bolt and expansion elements in the form of half-shells, which opposite each other enclose the screw bolts and their adjacent edges Form oblique to the longitudinal axis of the screw bolt wedge surfaces along which they are displaceable relative to one another, according to the main patent 1 960 734 the half-shells in cross section approximately U-shaped and their legs to form interlocking wedge surfaces are designed sawtooth-shaped by cutouts, the legs rest on the bolt shank and two opposite edge areas of the legs are bent inwards for holding it on the bolt are, characterized in that the inwardly curved edge regions of the legs a half-shell (4) are provided with a thread (8) that matches the thread of the screw bolt (1) is engaged. 2. Expansion dowel according to claim 1, characterized in that in a manner known per se two opposite edge areas of the legs of the half-shells (3, 4) each with clamping tongues (7) are formed, the two clamping tongues only one half-shell (4) on the inside with a thread (8) are given away. 3. Expansion dowel according to Claims 1 and 2, characterized in that the screw bolt (1) at the end lying in the borehole with a nut (11) and at the outer end with a head (2) is provided, the half-shell (4) resting against the nut with the thread is provided.