Fastening Element With a Cavity Containing an Explosive Charge

The invention relates to a fastening element having a hollow body or casing provided with a cavity containing an explosive charge for anchoring the element during explosion thereof.

Fastening elements that contain explosive charges are conventional; they involve the explosive rivets successfully utilized for the repair of airplanes at military airfields. Such explosive rivets, however, can only be utilized in the specific fields of application suitable for rivets.

The invention is based on the problem of providing an explosive fastening element which can be driven into the material without requiring a prefabricated opening. In particular, a nail element is to be created which has the effect of a rivet in the component to be attached and the effect of a nail in the component to which the first-mentioned component is to be fastened.

This problem is solved by a fastening element having the features of a rivet and of a nail. An explosive rivet-nail element is thus produced, by means of which a simultaneous riveting and nailing step is carried out. This element can be used, for example, in the fastening of facings on the outside of unfinished buildings, inner panelings in closed rooms, or when fastening clamping collars for conduits. A pre-bored opening for the novel rivet-nail element is required merely in the component which is to be attached. The novel rivet-nail element need not be especially anchored in this bore opening, although this can be done additionally. By the riveting-nailing step, the novel fastening element is anchored in the manner of a rivet in the pre-bored hole of a first component to be attached, while simultaneously the nail is driven into a secnd component to which the first component is to be attached and, by means of the fastening element, the first component to be attached is fastened to the second component. The explosive charge is ignited by heat transmitted either by thermal conduction, for example by placing a soldering iron at the end of the fastening element, or by induction heat produced with the aid of a high-frequency generator device directly in the fastening element by electric induction without contact and without heating up the non-induced surroundings of the fastening element.

To effect the connection by means of the fastening element of this invention, suitable are parts of all kinds of materials, for example, synthetic resin, wood, slate, or metal.

With the aid of one advantageous embodiment, a fastening element is provided which can be extended in the manner of a telescope and thus is capable of bridging even large distances between the component to be fastened and the component to which the first-mentioned component is to be attached.

The spacing between the component to be attached or fastened and the component to which the first-mentioned part is to be attached can be adjusted advantageously by a spacer bushing initially provided at the fastening element according to another embodiment.

The fastening element can be provided with a head at the end where the explosive charge is located so that it can be passed through the component to be fastened. It is also possible to insert the fastening element of this invention with its end adjacent to the explosive charge in a blind hole in the component to be fastened, in which the end of the fastening element on the explosive charge side is then spread apart or anchored by a riveting effect.

In case the heat of ignition is transmitted to the explosive charge by heat conduction, the sleeve and/or the material of the novel fastening element surrounding the explosive charge consists preferably of a material of high heat conductivity, such as, for example, steel, iron, aluminum, or a copper alloy.

Additional details of the invention can be seen from the following description of several embodiments with reference to the drawings wherein:

FIG. 1 shows an axial sectional view of a first embodiment of the fastening element of this invention;

FIG. 2 shows an axial sectional view of another embodiment of the fastening element of this invention wherein the explosive charge is arranged in the head of the nail;

FIG. 3 shows an axial sectional view of a another embodiment of the fastening element according to this invention wherein the element is telescopically extended during the riveting and nailing process; and

FIG. 4 shows an axial sectional view of a fourth embodiment of the fastening element according to the invention with a spacer bushing arranged thereat and showing the arrangement of the fastening element in the component to be fastened and also showing the component to which it is attached.

In the drawings, identical parts have the same reference numerals

FIG. 1 shows the basic construction of the novel fastening element. A metallic sleeve 1 is sealed at one end and contains at that point an explosive charge 3. At its other end, the sleeve 1 is folded shut or swaged, and the folded portion 7 leaves a small opening 7'. In the sleeve 1, a nail 5 is disposed having a shank 66, a tip 6a, and a head 6. The nail 5 is entirely housed within the sleeve 1; the head 6 adjoins the explosive charge 3 while the end of its tip 6a is located in the opening 7' left by the folded portion 7. The head 6 of the nail 5 is separated with respect to the explosive charge 3 by a cover layer 4 which consists of paper, for example.

The explosive charge 3 consists, for example, of a mixture of 50 to 70% by weight of a metallic powder, (e.g. iron) and the remainder a mixture of tetrazene and nitromannite. In this mixture, nitromannite can be replaced by nitrocellulose or pentaerythrol tetranitrate and iron powder can be replaced by powder of metallic aluminum, magnesium, or alloys of these metals.

At the folded portion 7 of the sleeve 1, the sleeve has a larger wall thickness. The folded portion retains the nail 5 at the lower end of its tip 6a.

The head 6 of the nail 5 is fashioned so that it can be displaced in the manner of a piston in the cavity of the sleeve 1, driven by the gases produced by the explosive charge 3 during the explosion. The shank 6b of the nail has a smaller diameter than the head 6, so that the head with the thus-formed shoulder forms a stop which is retained by the inner edge of the enlarged opening formed by the folded portion 7 during the displacement of the nail 5, and thus prevents a complete explusion of the nail 5 from the sleeve 1. To ensure this, the sleeve 1 has an enlarged wall thickness at the opening left free by the folded portion 7.

In the illustrated embodiment, the fastening element has a head 2 that is shaped to prevent a slipping of the fastening element through the pre-bored hole in the component to be fastened, in one direction.

In the embodiment of FIG. 2, the explosive charge 3 is not directly accommodated in the cavity of sleeve 1, but rather is disposed in a cavity 8 in the head 6 of nail 5. This cavity 8 is open toward the sealed end of sleeve 1 and at this aperture the explosive charge 3 is protected by a cover 4, for example, made of a paper sheet.

FIG. 3 shows an embodiment of the fastening element of this invention wherein the element is extended telescopically during the riveting and nailing step. In this case, the nail 5 is not disposed directly in the outer sleeve 1 but is seated in an intermediate sleeve 10 which, in turn, is located within the outer sleeve 1.

Analogously to the basic embodiment, the intermediate sleeve 10 has, at its end on the side of or adjacent to the explosive charge, a flange 15 displaceable in the manner of a piston in the sleeve 1 upon the explosion of the explosive charge 3. With its other end, which is rounded, the sleeve 10 is housed in a --correspondingly large --opening 7" which is left free by the folded portion 7 of sleeve 1. A shoulder 17 at the sleeve 10 takes care of an additional positioning of nail 5 by the contact of nail head 6 with this shoulder, so that the nail 5 is fixed in position until the intentional deployment of the fastening element is ensured not solely by the folded portion 12 at the tip 6a of the nail.

At the sealed end, the explosive charge 3 is seated in the sleeve 1 in a dish 8a open toward the sealed end of the sleeve 1. The bottom of dish 8a adjoins the flange 15 of sleeve 10, a paper sheet 9 is being interposed. The bottom of dish 8a is perforated by a bore, covered by the sheet 9, and also filled by the explosive charge 3.

The sleeve 10 is thin-walled and is preferably made of steel. Analogously to sleeve 1 of the heretofore described simple embodiments, this sleeve 10 has a folded portion 12 with an opening 12' left free by this portion, in which the end of the tip 6a of the nail 5 is disposed. In contrast to sleeve 1, sleeve 10 is, however, left unsealed at the end oppositely to the folded portion 12, so that it is open rather than closed. In the open end the head 6 of the nail 5 is located, namely directly in front of the bore, likewise filled with explosive, in the bottom of dish 8a. The head 6 of nail 5 is displaceable in the sleeve 10 in the same way by means of the explosion gases as in case of sleeve 1 in the simple embodiments. Thus, it will be understood that the sleeve 10 is also displaced from the outer sleeve 1 as the nail 5 is displaced from sleeve 10.

FIG. 4 shows another variation for accommodating the explosive charge 3 in the sleeve 1. As can be seen from the drawing, the explosive charge 3 is pressed into a dish 8b which is open toward the sealed end of sleeve 1. At this point, the explosive charge 3, as in the other embodiments, is protected by a cover 4. To dish 8b is fashioned separately from the head 6 of the nail 5, and the head 6 of the nail contacts the bottom of dish 8b.

In FIG. 4, another version of the present fastening element is furthermore illustrated wherein the element has a spacer bushing 11. The spacer bushing 11 is pushed over the lower section of sleeve 1 and provided with a contact flange 16 at the end of its opening by means of which it is pushed over the sleeve 1. This contact flange 16 is supported on the surface of the component 13 to be fastened. At its other end, the spacer bushing 11 has a bottom in which a bore is provided for the penetration of nail 5.

Independently of the depth of the pre-bored hole in the component 13 to be fastened, into which the fastening element including the sleeve 1 is inserted, the contact flange 16 determines the depth of such insertion. By placing the bottom of the spacer bushing 11 against part 14, to which the first-mentioned component 13 is to be attached, an exactly defined spacing is thus established between the component 13 to be fastened and the component 14.

The functioning of the fastening element according to this invention can be seen best from FIG. 4. When heating the explosive charge 3 about 160.degree. C., the explosive is ignited and drives the nail 5 from the sleeve 1 through the opening left by the folded portion 7. During this step the folded portion 7 is expanded by the wedge effect of the tip 6a of nail 5, but only to such an extent that the shank of the nail 5 will penetrate. At the same time, due to the explosion, a riveting effect is achieved in that sleeve 1 is bulged outwardly in the zone of the explosive charge 3. Thereby, the sleeve 1 is anchored in the component 13 to be fastened, as illustrated in dashed lines in FIG. 4. The head 6 of nail 5, driven in the manner of a piston by the explosion gases is stopped at the end of its stroke by the opening left by the folded portion 7, which has been widened only up to the diameter of the nail shank. The nail 5 then sits with tip and shank in component 14, to which the component 13 to be fastened was supposed to be attached.

In the embodiment according to FIG. 3, the nail 5 is advanced within the intermediate sleeve 10 to such an extent that its head 6 is stopped by the folded portion 12 of the intermediate sleeve 10. Likewise, the intermediate sleeve 10 is driven out through the folded portion 7 of sleeve 1 until its flange 15 is abuts the folded portion 7. The fastening element is thus telescopically extended in this embodiment.