DE2419111A1 - Dowel for fitting in plaster walls - has self cutting thread and pocket for swarf - Google Patents

Abstract

The dowel is suitable for fitting in walls made from plaster or other slow strength materials. The dowel is provided with an axial hole in which support screws etc. can be mounted. The thread on the dowel has been partly cut away along two planes. One plane leaves sharp tips on the screw thread, the other plane is at right angles to the first plane. The sharp edges have been slightly deformed so that the face of the threaded is enlarged and the edges are proud of the sides of the thread. These edges form the cutting edges of the self-tapping thread. A deep trough is cut in the dowel near the first two cutting threads. Swarf cut by the thread can find its way into this trough.

Description

Dowels for fastening in particular in plaster walls or the like.

The invention relates to a dowel for fastening in particular in Gypsum walls, aerated concrete walls or the like material of comparatively lower load capacity with an axial cavity for receiving a fastening element.

Conventional dowels are not really suitable for plaster walls or soft materials of this kind, as they particularly damage the material under heavy loads slowly crumble along the entire adjoining borehole wall over time. In this way, an initially tight-fitting dowel can withstand the surrounding material of the borehole wall easily pulled out Heavy objects such as bookshelves, wall cabinets and sinks can therefore not be permanently attached to such walls even with large dowels be attached.

On the other hand, there has been a need for a long time, also on walls from material of comparatively low load capacity to heavy objects attach.

So far, one has for this in a complex manner, for example, continuous Screw connections attached, preferably on the opposite wall side are connected to a plate-like extension.

The object of the invention is therefore, in particular od for plaster walls. Like. To create a dowel-like fastening element, which can subsequently be easily attached as well as being firmly anchored later even with greater loads is.

To solve the problem, the invention proposes in particular a Screw-in dowel formed dowel front, the one with outwardly protruding Einohraubgewin de is provided that has at least one self-tapping edge. This screw-in dowel, briefly below Called dowel, is form-fitting in a for this purpose provided borehole can be screwed in and forms with its thread-shaped outside a large attack surface for its surrounding lightweight material.

Preferably, all edges can be along at least one longitudinal plane be designed as self-tapping edges, at least one, preferably both of a tooth flank adjacent edges axially slightly above the associated flank can protrude.

In particular, these cut edges cut into the lightweight construction material immediately insert the thread with approximately the necessary clearance. This avoids that the thread flanks a corresponding pressure on the masonry when screwing in exercise. In this way, for the area surrounding the anchor, the receiving Wall prevents it from cracking open or from being subjected to excessive pressure is.

A dowel of the above type has also been proposed, which is made of plastic and between the area of its self-tapping Edges and its axial cavity for receiving a fastening element Has breakthrough that serves to remove the machined material. Such Dowels have proven themselves in many ways in practical tests however, there are also some disadvantages. The aforementioned cavity brings for example a weakening of the entire anchor with it.

In addition, metric threads do not work well in plastic anchors incision.-On the other hand, one can use metal dowels which, in their axial cavity, have a metric Have threads or should have been cut, practically do not use them. Chippers Material od. Like. Drill dust "can and should then through this breakthrough in the axial Cavity get and interferes with such a thread connection with the metric thread quite considerably, making them partly unusable. In addition, those are earlier proposed plastic dowels are not heat-resistant enough for all cases.

In order to eliminate the aforementioned disadvantages, suggests further training of this invention that in the area of the dowel inserting one opposite the central dowel cavity closed receiving chamber provided is, the volume of which is preferably at least about so large that the thread cutting the wall material (plaster, etc.) machined from the dowel to be accommodated in this receiving chamber is.

Such a dowel can well be made of metal and in its central cavity e.g. have a metric thread The central cavity remains unaffected by the machined material when cutting the entire dowel into the wall. In addition, such a metal dowel is fire-resistant and very dimensionally stable. With greater powers can be transferred to him. He can also - compared to the corresponding Plastic dowels - to be screwed into walls that offer somewhat greater resistance.

Compared to conventional threaded screws, the outer thread diameter D the screw-in thread must be considerably larger than the dowel core outer diameter d, preferably D: d about 3: 1 to 1.8: 1. The pitch of the thread can be about 10 to 15 mm, preferably 12 mm. Tests have shown that both the aforementioned Diameter ratios as well as the pitch ratios of Thread are particularly favorable, and tests have also shown that this Diameter ratios in the scope of dowel dimensions, how to use them knows their way around lightweight construction materials, are well suited. Can advantageously in the dowel according to the invention at the outer end of its axial cavity driving grooves od. The like. Einrehhilfselemente be attached for receiving a screwing tool. The aforementioned measures make it easier to screw in, e.g. with the help of a Screwdriving 5.

Advantageously, the core piece can be reinforced at its outer end, e.g. be frustoconical. On the one hand, this has the advantage that breakout points in the plaster wall or the like. Are covered. In addition, you get a reinforced attachment of the anchor as well as a reinforcement of this anchor itself in the area of the outer In the end. The latter is i.a. for screwing in and the necessary power transmission advantageous.

In order to make screwing in the dowel much easier, the screw-in thread towards the outside End continuous in diameter gain weight.

In this way, the deeper penetrating dowel with a the resulting stronger hold maintain an almost constant screw-in force will.

The cutting surfaces of the outer threads, especially those which are in the area of the receiving chamber are opposite the adjacent longitudinal center plane set back. This gives you, among other things, a cheaper one, namely compared to 900 smaller ones Cutting angle, which makes it easier for the dowel to penetrate.

According to a further development of the invention is in the axial cavity a pre-cut thread, preferably metric or the like, comparatively fine Thread provided. Appropriately, this is not continuously formed there, but only cut into several axially directed sectors. To do this, in this cavity corresponding ribs radially inwardly. That makes the production easier of the thread and keeping this cavity clean. This means that it will be screwed in several times of fasteners favors what especially when screwing of wood screw threads in plastic dowels of a similar type associated with disadvantages is. This thread, which is only formed from several sectors, is sufficient for the ones that occur or the dowel and in particular its wall from reasonable loads.

Metal, in particular zinc, is suitable as the material for the dowel, that is processed as a die-cast.

The following is the invention with its essential details explained in more detail with reference to the drawing. It shows: FIG. 1 a dowel in perspective Representation, Fig.la a rear view of a section of the screw-in thread according to viewing direction A in Fig. 1, also in a perspective view, Fig.2 the dowel according to the section line II-II in Fig. 1, Fig. The dowel according to the section line III-III in Fig. 1, Fig.4 the dowel according to Fig. 1 in side view and partly in section, FIG. 5 shows an end view of the dowel in the viewing direction F according to FIG. 1, FIG. 6 a partial plan view of the screw-in thread with no protruding cutting edges and Fig. 7 a partial plan view of the screw-in thread with slightly axially widened protruding cutting edges.

The dowel (Fig. 1) is stronger than a screw-in dowel with an outward facing protruding screw-in thread 2 provided. Whose cutting surfaces S are through a Recess Sp created, which essentially has an open-edged cross-sectional sector separates from this screw-in thread, as particularly good in Fig. 1 and 2 can be seen. The recess Sp is namely essentially through the freely protruding cutting surfaces provided with self-cutting edges 3 and formed by cross-sectional areas 8 a of the thread 2. There are three in FIG Cutting surfaces S in a longitudinal plane L (compare FIGS. 1 and 2). Also are in the area of a receiving chamber 20 cutting surfaces S are also provided, which in a Level M lie (compare FIGS. 1 and 3). These cutting surfaces lying in the same plane are - seen in the direction of rotation - a little further compared to the longitudinal center plane G. set back.

Their cutting edges are marked with Da. Because of this center offset according to the plane L or N, more acute cutting angles α and β result. the already mentioned receiving chamber 20, hereinafter also referred to as "chamber 20" for short, which for picking up the machined material produced when screwing in the dowel, can be clearly seen in FIGS. 1, 3 and 4. The immediately in the area of this chamber 20 lying cut surfaces S, which lie in the aforementioned plane M, are located in one plane with the chamber side wall 41 adjacent to them (see FIG. 5). This not only makes production easy, but also the shredded material, below also called "drilling dust" for short, can be done without difficulty get into the chamber. According to the invention, the volume of this chamber is so large that that the chamber contains at least the drilling dust produced when cutting the external thread 2 can accommodate. In the case of a single-start thread, this essentially corresponds to this Volume of a cut thread. The chamber 20 can be a little larger than this volume, but should not be significantly larger, so that no unnecessary weakening of the anchor occurs.

The chamber 20 is located in the area of the inner insertion end 7 of the dowel, i.e. at the end> that is inserted into the wall first. there the core 11 of the dowel is designed like a bearing and stands over the first thread turn before. This way you can find the hole in the wall when you first cut the dowel in this a better hold.

In Fig. 1 you can see the self-cutting edges 3 and 3a, while with the approximately right-angled edges formed by the recess Sp 8 are designated. These edges 8 enclose the already mentioned surfaces 8a.

Figures 1 and la show a particularly clear development recognize the invention, according to which both tooth flanks 9 directly in the self-tapping Edges 5 and 3a protrude somewhat axially widened. The dashed lines in FIG Line 10 which follows directly behind these cutting edges 5 or there Tooth flank 9 of the screw-in thread 2 piping (compare also the corresponding kink edge 10 in Fig. La). In Fig. 7 is a view of the thread flank from above for clarity 9 together with the corresponding environment. You can see there well, like the self-tapping ones Edges protrude radially. For comparison, an embodiment analogous to FIG. 7 is shown in FIG shown where the self-tapping edges do not protrude laterally, so the Have an outline shape that can be obtained by machining the recess Sp in the threads without further ado. When the dowel 1 is made of metal, the result is additional advantage that the axially widened protruding self-tapping Edges), since according to Fig. 7, 1 and la are particularly fast-acting, since these f4etallkanten are also sufficiently hard and resistant to the l! Seichbauststoff. Such axially widened edges 5 respectively Since wear a layer of less Prepare in the soft building qff. This prevents the thread 2 from moving with the tooth flanks 9 apply to the surrounding wall material with pressure. Damage this not very resistant wall material can be avoided. the Edges5 or 5a or 3b remain sharp during the entire screwing-in process and have a material-removing effect. This is also done with D7ibeh made of plastic; in a particularly effective manner, however, with a dowel made of zinc, which is injection-molded can be made accordingly precisely.

In Fig. 2 and 5 can be seen with the help of the drawn tangent T, which is applied to the outer circumference of the screw-in thread 2 at point 57 and 58, respectively is that by the offset of the plane L or M with respect to the longitudinal center plane G a Reduction of the cutting angle α or β compared to 900 is present. The farther that is, such a plane L or M is removed from the corresponding longitudinal center plane G. the smaller the cutting angle 01 or

In Fig. 2, 4 and 5, the sectors 55 are for receiving the internal thread 56 or this itself is shown.

Fig. 4 shows the anchor 1 on an enlarged scale. Here will be characteristic diameter ratio of dowel core d and outer diameter D as well as the relatively large pitch of the thread is clear. The outer thread diameter In the exemplary embodiment, D is approximately twice as large as the outer diameter of the dowel core d.

But there are also ratios of D: d of about 5: 1 to 1.8: 1 proven. The distance between the individual threads is 12mm. As well usable However, there are also pitches of the thread in the order of magnitude of about 10 up to 15 mm.

Fig. 4 also shows that the outward, self-tapping Edges 3, 3a in the direction of the outer end 6 of the dowel 1 continuously in the Increase in diameter. The outer thread diameter in the vicinity of the outer end 6 D1 is therefore somewhat larger than the outer thread diameter at the insertion end 7 D. This formation of the thread course in connection with the cutting edges 3 or 3a or 3b has the advantage that the thread turns as it is screwed in further can always work firmly into the surrounding wall, on the other hand the cutting edges ensure continuous expansion in such a way that it does not have to oversized Tensions in the wall material can occur.

This gives the dowel a particularly firm fit also gentle treatment of the wall when cutting threads.

4 and 5 show that the dowel 1 at the outer end 6 is a frustoconical Has extension 12. This can be used to cover the edge of the wall hole.

At the outer end 6 at the end face 51 (compare FIGS. 1, 4 and 5) driving grooves 13 are provided. With such screwing aids for receiving a Screwing tool, e.g. a screwdriver-like blade, you can insert the dowel 1 Screw in well with the help of a drill ratchet or a hand drill.

By designing the dowel 1 with a self-tapping screw-in thread 2 results in a form-fitting> connection between the dowel and the wall. By the intended receiving chamber 20 or the like is prevented that by the drilling dust too much pressure exerted on the wall of the borehole; can be. In particular the opposite to the axial cavity H closed Chamber 20 prevents that drill dust or the like interferes there in the area of the thread 36. This drill dust od.

Like. Can also in that area of the anchor 1 where no chamber 20 more is available, can be accommodated well, namely in the area of the Recess Sp, which remains free in the area of the incised threads. try have shown that the dowel 1 according to the invention in the area of the threads 2 provided volume is sufficient for this. Such volume ratios are reliably guaranteed if the cutting surfaces S are the cross-sectional surfaces 8a stand approximately at an angle VOn of 90 according to the invention.

All in the description, the following claims and drawings The construction details and features shown are familiar both individually and in any combination with one another be essential to the invention.

- patent claims -

Claims (1)

Claims dowels for Belestigen od in particular in plaster walls. Like. Material of comparatively lower load capacity with an axial cavity To accommodate an attachment element, which is not shown e t that the dowel (1) is a screw-in dowel with an outwardly protruding screw-in thread (2) provided isç that has at least one self-tapping edge ()). 2. Dowel according to claim 1, characterized in that all edges (3) formed as self-cutting edges along at least one longitudinal plane (L) are. 5. Dowel according to claim 1 or 2, characterized in that at least one, preferably both of a tooth flank (9) adjacent edges (); 3a) axial protrude slightly over the associated flank (Fig. 7). 4. Dowel according to one or more of claims 1 to 3, characterized in that that in the area of the plug insertion end (7)> seen in the direction of rotation, immediately a receiving chamber in front of at least one cut surface (S) with self-cutting edges (3a) (20) is provided, the volume of which is preferably at least about so large that to accommodate the material machined during thread cutting in this chamber (20) is. 5. Dowel according to one or more of claims 1 to 4, characterized that the outer thread diameter (D) of the screw-in thread (2) is considerably larger as the dowel core outer diameter (d), preferably D: d is about 3: 1 to 1.8: 1. 6. Dowel according to one or more of claims 1 to 5, characterized in that that the pitch of the thread (2) is about 10 to 15 mm, preferably about 12 mm. 7. Dowel according to one or more of claims 1 to 6, characterized in that that at the outer end (6) of its axial cavity (5) Mithehmernuten (13) od. Like. Screw-in auxiliary elements for receiving a screw-in tool are attached. 8. Dowel according to one or more of claims 1 to 7, characterized in that that the internal thread (56) in axially arranged sectors (35) of the central Dowel cavity (H) are located, preferably in three or more sectors (55). 9. Dowel according to one or more of claims 1 to 8, characterized in that that the dowel is at least the greater part of its external thread (2) in Has a cross-section extending recess (Sp) beginning at the other end of the dowel (7), one flank of which from the longitudinal plane (L) and its other flank is formed by cross-sectional areas (8a) (Fig.1). 1t0. Dowel according to claim 9, characterized in that the flanks the recess (Sp) are at an angle of about 900 to each other (Fig.2). 11. Dowel according to one or more of claims 1 to 10, characterized characterized in that the ßinschraubgewinde (2) in the direction of the outer end (6) of the dowel (1) increases in diameter> preferably increases continuously. 12. Dowel according to one or more of claims 1 to 11, characterized characterized in that the self-cutting edges (5, Da, db) opposite to this parallel longitudinal center axis (G) seen in the direction of rotation, are set back (Fig. 2 and 5) 13. Dowel according to one or more of claims 1 to 12, characterized in that that the dowel core (11) is reinforced at its outer end (6), e.g. frustoconical is expanded. 14. Dowel according to one or more of claims 1 to 13, characterized characterized in that the cut surfaces lying in the region of the receiving chamber (20) (S) are set back more than the longitudinal center axis (G), preferably lie in one plane with the adjacent chamber side wall (41). 15. Dowel according to one or more of claims 1 to 14, characterized characterized> that the chamber (20) extends in the dowel longitudinal direction only over one or two threads located in the area of the plug inserting end (7) (2) extends. 16. Dowel according to one or more of claims 1 to 15, characterized characterized in that the thread turns (2) a substantially triangular, optionally have an approximately arched outline shape on the flanks (9). 17. Dowel according to one or more of claims 1 to 16, characterized characterized in that the dowel core (11) bearing-like somewhat over the first thread turns (2) as well as via the admission chamber (20) axially protrudes. 18. Dowel according to one or more of claims 1 to 17, characterized characterized in that in its axial cavity (H) pre-cut thread, preferably metric or fine thread is provided.