self-drilling bolt

Abstract

The invention relates to a self-drilling bolt (100) comprising a self-drilling screw (1) and a nut (200) capable of being mounted on the self-drilling screw (1), said self-drilling screw (1) comprising a body (2) having at least one threaded area and extended by a drill point (3) provided with a smooth end (4) and of pointed shape. According to the invention, the drill point (3) comprises a thread (6) capable of receiving the nut (200) so that said nut (200) can be screwed around said drill point (3). Figure No. 1

Description

Title of the invention: self-drilling bolt

[0001] The present invention relates to a self-drilling bolt. In order to remove any ambiguity, such a bolt combines a self-drilling screw and a nut capable of being mounted around said screw.

[0002] For the rest of the text, the expressions “bolt” and “self-piercing bolt” are equivalent.

[0003] A self-drilling screw is very often used to make a hole directly in a material which may for example be metal or wood, without having to carry out other prior operations of preparation of said material or pre-drilling of it, and therefore without having to use other tools. A self-drilling screw differs from other categories of screws thanks to its drill-shaped tip, and a helical thread.

[0004] Patent application FR 1462009 relates to screws capable of receiving a nut, and capable of drilling and / or tapping a sheet of significant thickness without the thread intended for the nut being damaged, which means that it is possible to: -easily drive the screw through sheet metal parts without the need to drill or tap them first, -easily apply a nut to fix the parts in their assembly position.

[0005] However, a disadvantage linked to the screws described in this document is the limitation of the thickness of the supports to be assembled. Indeed, these screws have been designed to drill and / or tap thin sheets exclusively, due to the geometry of the portion of continuous solid threads. In addition, these screws are not intended for wooden supports, or more generally for supports made of materials other than sheets.

[0006] A self-drilling bolt according to the invention overcomes the main drawbacks encountered with bolts of the state of the art.

[0007] The subject of the invention is a self-drilling bolt comprising a self-drilling screw and a nut capable of being mounted on the self-drilling screw, said self-drilling screw comprising a body having at least one threaded zone and extended by a drill point provided with a smooth end and of pointed shape.

[0008] According to the invention, the drill bit tip has a thread that can accommodate the nut so that said nut can be screwed around the drill bit tip. The main original feature of a self-drilling bolt according to the invention is that the drill bit tip has a thread onto which a nut can be screwed. The screw has a pointed end, which is smooth and which can for example be conical or pyramidal in shape, allowing it to be self-drilling. The thread of the drill bit tip can be well marked, moderately marked or weakly marked. It is sufficient for it to be marked to allow the nut to be screwed around this drill tip. The smooth end preferably has cutting lips formed from grooves to facilitate the drilling function of the bolt. Advantageously, the self-drilling screw has a drive means placed at one end of the screw which is opposite to that having the pointed and smooth end. This drive means has a geometry and / or reliefs which are intended to interact with a rotation member of a portable electric machine, such as for example a drill or a drill. This rotation member can for example consist of a rotating bit.

[0009] According to a possible characteristic of the invention, the threaded body and the drill tip each have an identical thread, said threaded body and said drill tip having equal internal diameters. For this configuration, the thread of the body and the thread of the drill tip are identical, only the smooth and conical end of the screw contributing to the drilling of the hard material. In this way, such a screw will only be able to drill thicknesses of hard material, for example less than 1 mm.

[0010] According to a possible characteristic of the invention, the threaded body has a formed thread and the drill tip has a moderately formed thread, said threaded body and said drill tip having equal internal diameters. For this configuration, the external diameter of the thread of the drill tip is less than the external diameter of the thread of the screw body, with the consequence that the smooth and conical end and a part of the drill tip will contribute to the drilling of the hard material. In this way, such a screw will only be able to drill thicknesses of hard material less than 2.5 mm.

[0011] According to a possible characteristic of the invention, the threaded body has a formed thread and the drill tip has a weakly formed thread, said threaded body and said drill tip having an identical internal diameter. For this configuration, the external diameter of the thread of the drill tip is much smaller than the external diameter of the thread of the body of the screw, with the consequence that the smooth tip and a large part of the drill tip will contribute to the drilling of the hard material. In this way, such a screw will be able to drill thicknesses of hard material greater than 2.5 mm.

[0012] According to a possible characteristic of the invention, the drill tip has at least one groove extending over the entire length of said tip and of the end, said groove originating at the periphery of a first end of the drill tip in contact with the threaded body and extending to a second end corresponding to the end of the end. The groove of the screw of a bolt according to the invention is equivalent to a fictitious removal of material from the drill tip and of the end. This groove has a variable depth, which increases progressively from the first end of the drill tip to the second end corresponding to the end of the smooth and conical end. The depth of the groove corresponds to its dimension considered along of a radial axis of the screw. This groove acts as a groove allowing in particular the evacuation of the material into which it is screwed, when it is fixed in said material at high speed by means for example of a motorized drill.

[0013] Advantageously, this groove is delimited by cutting edges, constituting cutting lips making it possible to promote the drilling of the material in which it will be fixed. The screw of a self-drilling bolt according to the invention may have two grooves promoting the evacuation of the material in which it has been fixed and also promoting the drilling of said material. The smooth pointed end of the screw will also participate in the drilling of the material, and can be configured to be able to drill said material more or less deeply.

[0014] Indeed: -the drill tip can be threaded and can be a perfect extension of the threaded body without any difference being made between said body and said drill tip. For this configuration, the bolt will only be able to drill small thicknesses of hard material such as for example steel or wood.

[0015] - the drill tip may have a moderately formed thread, and in this case the thickness of hard materials that the bolt can pierce will be greater. -the drill tip may have a weakly formed thread (less formed than the medium formed thread), and in this case the bolt will be able to drill through greater material thicknesses.

[0016] The presence of the groove is intended to: - make the drill tip of the screw more tapered than those of existing self-drilling screws, so as to facilitate drilling through a thickness of material, -to evacuate part of the material in which the screw is inserted, when the latter pivots around its axis of revolution to carry out the drilling operation, -to facilitate the drilling of a material thanks to the presence of cutting edges delimiting said groove.

[0017] According to a possible characteristic of the invention, the end of the screw comprises a conical wall and the angle of inclination of said wall defining this end with respect to the axis of revolution of the screw is between 10° and 85°. This angle of inclination is the angle that a generatrix of the smooth conical tip makes with the axis of revolution of said conical tip. This angle is chosen according to the characteristics of the material to be drilled and the thickness thereof. The smaller this angle, the more efficient the screw will be in drilling a material.

[0018] According to a possible characteristic of the invention, the edges of said at least one groove in the end are sharp, so that said end defines cutting lips which will promote the drilling of a thickness of material. These cutting lips will improve the drilling conditions, while the volume of the groove will contribute to the evacuation of the material dug by said screw.

[0019] According to a possible characteristic of the invention, the screw has two grooves arranged diametrically opposite each other, said two grooves being separated from each other by being distinct. These two grooves are separated from each other by thicknesses of the material constituting the screw. The presence of these two grooves will accentuate the effects produced by a single groove which are: -favor the drilling operation of the material in which the screw is intended to be fixed, - promote the evacuation of the material which will have been cut during the rotational driving of the tip of the screw into said hard material, - make the drill tip of the self-drilling screw more tapered.

[0020] According to a possible characteristic of the invention, the end of the screw comprises a widened frustoconical base extended by a conical section ending in a point, the angle of inclination of the frustoconical base relative to the axis of revolution of said end being less than that of the conical section relative to said axis. For this configuration, the smooth end of the screw comprises cutting lips with two angles, one corresponding to the widened base and the other corresponding to the conical section. In this way, drilling a hard material such as for example a metal will be easier, the cutting lips formed by the conical section ensuring good penetration of the smooth end into said hard material and the cutting lips formed by the widened base ensuring good cutting of this hard material.

[0021] According to a possible characteristic of the invention, the end of the screw comprises a widened frustoconical base extended by a conical section ending in a point, the angle of inclination of the frustoconical base relative to the axis of revolution of said end being greater than that of the conical section relative to said axis.

[0022] According to a possible characteristic of the invention, the self-drilling screw comprises a breaking groove so that said screw can be broken at said breaking groove and can therefore no longer constitute a harmful protuberance. Indeed, in certain configurations, the screw of a self-drilling bolt according to the invention can protrude very markedly behind a thickness of material that it has pierced, and can then constitute: -a hanging element, or -a dangerous point, or - an element of bulk that could hinder the installation of other objects in the immediate environment of the screw.

[0023] The breaking groove thus provides the possibility of breaking the screw in order to limit or even eliminate its protruding section.

[0024] According to a possible characteristic of the invention, the breaking groove is placed between the threaded body of the self-drilling screw and the drill point. This is a particularly suitable location of the breaking groove in a self-drilling bolt according to the invention, but is in no way limiting.

[0025] According to a possible characteristic of the invention, the self-drilling screw comprises at least one widening element projecting from an external surface of said screw and intended to widen a hole that said screw will have previously created. Such a widening element may for example consist of a fin, a tooth or a rib. When the self-drilling screw is rotated it will create a hole and when the widening element reaches the level of said hole, it will widen said hole by being rotated by said screw. This screw may have several widening elements distributed over its entire length, and / or distributed over its circumference.

[0026] A detailed description of several preferred embodiments of a screw according to the invention is given below, with reference to the following figures:

[0027] [Fig-1] [Fig. 1] is a side view of a first embodiment of a self-drilling bolt according to the invention,

[0028] [Fig.2] [Fig.2] is a side view of a second embodiment of a self-drilling bolt according to the invention,

[0029] [Fig.3] [Fig.3] is a side view of a third embodiment of a bolt self-piercing device according to the invention,

[0030] [Fig.4] [Fig.4] is a sectional view of the first embodiment of [Fig.l],

[0031] [Fig.5] [Fig.5] is a sectional view of the second embodiment of [Fig.2]

[0032] [Fig.6] [Fig.6] is a sectional view of the third embodiment of [Fig.3]

[0033] [Fig.7] [Fig.7] is a sectional view of a cylindrical drill bit of a screw according to the invention,

[0034] [Fig.8] [Fig.8] is a sectional view of a conical drill bit of a screw according to the invention,

[0035] [Fig.9] [Fig.9] is a top view of a screw according to the invention,

[0036] [Fig. 10] [Fig. 10] is a schematic side view of an outline of a drill tip of a screw according to the invention for which the tip is weakly marked,

[0037] [Fig. 11] [Fig. 11] is a schematic side view of an outline of a drill point of a screw of a bolt according to the invention for which the point is strongly marked,

[0038] [Fig. 12] [Fig. 12] is a schematic side view of an outline of a drill point of a screw of a bolt according to the invention, having two distinct parts,

[0039] [Fig.l2bis] [Fig.l2bis] is a schematic side view of an outline of a drill tip of a screw of a bolt according to the invention, having two distinct parts in an embodiment which is different from that illustrated in [Fig. 12],

[0040] [Fig. 13] [Fig. 13] is a side view of a fourth embodiment of a screw of a bolt according to the invention, showing a bolt body with two threaded parts separated by a smooth part

[0041] [Fig. 14] [Fig. 14] is a side view of a fifth embodiment of a screw or bolt according to the invention, showing the bolt with a separate threaded head for rotational drive.

[0042] [Fig. 15] [Fig. 15] is a side view of a sixth embodiment of a screw or bolt according to the invention, showing the bolt with a separate threaded head mounted thereon.

[0043] [Fig. 16] [Fig. 16] is a side view of a seventh embodiment of a screw of a bolt according to the invention, showing a drive indentation inside the body of the bolt

[0044] [Fig. 17] [Fig. 17] is a side view of an eighth embodiment of a screw of a bolt according to the invention, showing a drive tip in the extension of the body of the bolt

[0045] [Fig. 18] [Fig. 18] is a view showing the blank of a bolt with a drive tip in the extension before threading

[0046] [Fig. 19] [Fig. 19] is the view of [Fig. 18] after final machining, showing that the drive end is also threaded.

[0047] [Fig.20] [Fig.20] is a side view of a ninth embodiment of a screw of a bolt according to the invention and of a stop on the body of the bolt,

[0048] [Fig.21] [Fig.21] is a side view of a tenth embodiment of a screw of a bolt according to the invention and two parallel thicknesses of hard material into which the screw is intended to be inserted, said screw not yet having penetrated one of said two thicknesses,

[0049] [Fig.22] [Fig.22] is the view of [Fig.21], the screw acting as a spacer,

[0050] [Fig.23] [Fig.23] is a side view of an eleventh embodiment of a screw of a bolt according to the invention, showing boring fins between the drill tip and the body of the bolt

[0051] [Fig.24] [Fig.24] is a side view of a twelfth embodiment of a screw of a bolt according to the invention, showing boring fins on the body of the bolt,

[0052] [Fig.25] [Fig.25] is a side view of a thirteenth embodiment of a screw of a bolt according to the invention, showing a weakly threaded portion between the drill point and the threaded body of the bolt,

[0053] [Fig.26] [Fig.26] is a side view of a fourteenth embodiment of a screw of a bolt according to the invention, showing a breaking groove between the drill point and the body of the bolt,

[0054] [Fig.27] [Fig.27] is a side view of the fourteenth embodiment of the [Fig.29], showing the bolt with the drill point broken at the fracture groove,

[0055] [Fig.28] [Fig.28] is a side view of a fifteenth embodiment of a screw of a bolt according to the invention,

[0056] [Fig.29] [Fig.29] is a side view of a sixteenth embodiment of a screw according to the invention, which is inserted into a thickness of hard material,

[0057] [Fig.30] [Fig.30] is a side view of a seventeenth embodiment of a screw according to the invention, which is inserted into a thickness of medium-hard material, showing the nut screwed onto the drill tip once the assembly has been completed.

[0058] A self-drilling bolt 100 according to the invention comprises a self-drilling screw 1 and a nut 200 intended to be screwed onto said self-drilling screw 1. The self-drilling screw 1 comprises an elongated body 2 which is extended by a threaded drill point 3, ending in a smooth and conical end 4. In other words, the drill point 3 is inserted between the body 2 of the screw 1 and the smooth end 4. The term "smooth end" means that said end 4 is devoid of relief and therefore of a thread. The nut 200 is a common nut on the market, having a round tapped hole made in the usual manner.

[0059] The originality of a self-drilling bolt 100 according to the invention is that the nut 200 can be screwed around the threaded drill point 3. Generally, the body 2 of the screw 1 is cylindrical and comprises, at least over part of its length, a well-formed thread 5 around which a nut 200 is intended to be screwed. The end 4 of the screw 1 is conical in shape. The drill point 3 can be available in different configurations: -it can have a well-formed thread and constitute a perfect extension of the threaded body 2 without any difference being made between said body 2 and said drill tip 3, as illustrated in Figures 1 and 4. For this configuration, the internal diameter of the body 2 and the internal diameter of the drill tip 3 are equal. Similarly, the external diameter of the thread 5 of the body 2 and the external diameter of the thread 6 of the drill tip 3 are equal. With this type of geometry, the screw 1 will only be able to drill small thicknesses, typically less than 1 mm, of a hard material such as, for example, steel, since only the conical end 4 will participate in this drilling, - it may have a moderately formed thread, as illustrated in figures 2 and 5. For this configuration, the inner diameter of the body 2 and the inner diameter of the drill tip 3 are equal. On the other hand, the outer diameter of the thread 5 of the body 2 is greater than the outer diameter of the thread 6 of the drill tip 3. The teeth of the thread 6 of the drill tip 3 are less formed than the teeth of the thread 5 of the cylindrical body 2. With this type of geometry, the screw 1 can drill a thickness of a hard material which can for example reach 2.5 mm since a small part of the drill tip 3 which extends the conical end 4 will also participate in drilling the material, -it may have a weakly formed thread 6, i.e. less formed than the moderately formed thread of the previous configuration, as illustrated in figures 3 and 6. For this configuration, the inner diameter of the body 2 and the inner diameter of the drill tip 3 are equal. On the other hand, the outer diameter of the thread 5 of the body 2 is significantly greater than the outer diameter of the thread 6 of the drill tip 3. The teeth of the thread 6 of the drill tip 3 are much less formed than the teeth of the thread 5 of the cylindrical body 2, and in this case, the screw 1 can pierce a thickness of a hard material, for example greater than 2.5 mm, since a large part of the drill tip 3 which extends the conical end 4 will also participate in the drilling of the hard material.

[0060] Referring to [Fig.7], the drill tip 3 can be strictly cylindrical in shape over its entire length.

[0061] Referring to [Fig.8], according to another embodiment, the drill tip 3 may be of slightly frustoconical shape, the external diameter of said drill tip 3 gradually decreasing from one end of said drill tip 3 which is in contact with the cylindrical body 2, to one end thereof which is in contact with the smooth end 4 of conical shape.

[0062] Referring to Figures 1 to 3, 7, and 8, a screw 1 of a self-drilling bolt 100 according to the invention, is that it has two grooves 7, 8 extending from the periphery of a first end of drill tip 3 which is in contact with the cylindrical body 2, to a second end corresponding to the tip of the smooth and conical end 4. In this way, each groove 7, 8 extends over the entire length of the drill tip 3 and over the entire length of the conical end 4. Each groove 7, 8 has a variable depth, increasing regularly from the first end of the tip 3 to the second end of said drill tip 3, the depth constituting the dimension of the groove 7, 8 considered along a radial axis of the drill tip 3.Similarly, the width of each groove 7, 8 increases regularly from the first end of the drill tip 3 to the second end of said drill tip 3, the width constituting the dimension of the groove 7, 8 considered along the circumference of the drill tip 3. Schematically, each groove 7, 8 is delimited by two walls 9, 10 connected to each other by an intersection line extending along a longitudinal axis of the screw 1 and connecting the periphery of the first end of the drill tip 3 to the second end of said drill tip 3, said intersection line materializing the depth of the groove 7, 8 in the screw 1.

[0063] The two grooves 7, 8 are arranged on the screw 1 being diametrically opposed and perfectly separated from each other by thicknesses of material 14, 15. Each of the grooves 7, 8 has a cutting edge 16, 17 in the conical end 4, each of said two edges 16, 17 playing the role of cutting lips intended to promote the drilling of the hard material in which the screw 1 is intended to be fixed.

[0064] The grooves 7, 8 created in the drill tip 3 and in the conical end 4 of the screw 1 of a self-drilling bolt 100 according to the invention, have a triple function: - make the drill tip 3 of screw 1 more tapered, so as to facilitate drilling through a thickness of material, - evacuate part of the material into which the screw 1 is inserted, when the latter pivots around its axis of revolution at high speed to carry out the drilling operation, - promote the drilling of a material thanks to the presence of the cutting lips 16, 17 delimiting said groove 7,8.

[0065] The cutting lips 16, 17 created when making the two grooves 7, 8 in the screw 1, act like a conventional drilling bit, found on current self-drilling screws. It is important to remember that the smooth end 4 is devoid of thread. The cutting lips 16, 17 make it possible to cut and drill the thicknesses of material in which the self-drilling bolts 100 according to the invention will be installed.

[0066] Referring to Figures 10 and 11, the conical end 4 has a variable angle of inclination a depending in particular on the thickness of the hard material to be drilled. This angle a is between 20° and 170°. With a more pointed smooth end 4, corresponding for example to an angle a close to 20°, it will be easier to drill through greater thicknesses of hard material.

[0067] The tip of the screw has cutting lips forming an angle alpha a of between 20° and 170°.

[0068] Referring to [Fig. 12], according to another embodiment of a self-drilling bolt according to the invention, the smooth end 4 comprises a widened frustoconical base 18 extended by a conical section 19 ending in a point. The angle of inclination of the frustoconical base 18 relative to the axis of revolution of the smooth end 4 is less than the angle of inclination a of the conical section 19 relative to said axis of revolution. The angles co and a appearing in [Fig. 12] respectively represent twice these angles. For this embodiment, the angle co is less than the angle a. Indeed, for easier drilling of a metal, it is preferable to have an end 4 that is not too pointed, in order to have an end 4 having good penetration with the least closed angle a, and a good cut with the most closed angle co.

[0069] Referring to [Fig.l2bis], according to another embodiment of a self-drilling bolt according to the invention, the smooth end 4 comprises a truncated conical base 18 widened extended by a conical section 19 ending in a point. The angle of inclination of the truncated conical base 18 relative to the axis of revolution of the smooth end 4 is greater than the angle of inclination a of the conical section 19 relative to said axis of revolution. The angles co and a appearing in [Fig. 12] respectively represent twice these angles. For this embodiment, the angle co is greater than the angle a.

[0070] Referring to [Fig.13], according to an alternative embodiment of a self-drilling bolt 100 according to the invention, the body 2 of the screw 1 is partially threaded, so that an unthreaded zone 20 of said body 2 is framed by two threaded zones 21, 22 thereof, a nut 200 being mounted on each of said two threaded zones 21, 22.

[0071] Referring to [Fig.14], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the body 2 is fully threaded and a nut 200 is mounted on said body 2, said nut 200 having a separate threaded head for rotational drive.

[0072] Referring to [Fig.15], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the body 2 is entirely threaded and a nut 200 is mounted on said body 2. For this embodiment, a blind nut 26 is screwed to one end of the body 2 which is opposite the drill tip 3, having the two grooves 7, 8, allowing the screw 1 to be driven in rotation, for drilling and tightening.

[0073] Referring to [Fig.16], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the body 2 is entirely threaded and has at one of its ends which is opposite to that having the two grooves 7, 8, a hollow drive imprint 27 included in said body 2 and intended to receive the tip of a tool designed to rotate the screw 1 around its axis of revolution. A nut 200 is mounted on the threaded body 2 of the screw 1.

[0074] Referring to [Fig. 17], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the body 2 is entirely threaded and has at one of its ends which is opposite to that having the two grooves 7, 8, a projecting drive end piece 28 by means of which the screw 1 will be driven in rotation around its axis of revolution. A nut 200 is mounted on the threaded body 2 of the screw 1.

[0075] Referring to [Fig. 19], it is possible, from a blank of screw 1 having a smooth cylindrical body 2 and a drive end piece 29, for example of parallelepipedal shape and projecting from said smooth body 2, as illustrated in [Fig. 18], to manufacture simply and during the same operation, a screw 1 having a fully threaded body 2 and an end piece 29 only threaded at its apexes. In this way, a nut 200 can then be screwed onto the drive end piece 29 threaded at its apexes. This perspective is interesting, because for good rotational training or for good maintenance of the drive sleeve, the size of the drive tip 29 must not be too small, especially for long screw lengths 1.

[0076] Referring to [Fig.20], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the screw 1 has a stop 30. More precisely, the body 2 of the screw 1 has a smooth segment 31 and a threaded segment 32 extended by the drill point 3 and the smooth end 4 provided with the two grooves 7, 8, the external diameter of said smooth segment 31 being greater than that of said threaded segment 32. The stop 30 is constituted by the shoulder created by this difference in diameter. The thickness 33 of material to be drilled is thus wedged between said stop 30 and a nut 200 which will have been screwed onto the threaded segment 32 of the body 2.

[0077] Referring to Figures 21 and 22, according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the screw 1 may comprise a stop 35 having two functions: - a drilling function, for example to drill a first sheet 36, as illustrated in [Fig.2] 1, - a stop function against a second sheet 37 to stop the travel of the screw 1 once said stop 35 has pierced the first sheet 36, as illustrated in [Fig.2] 2.

[0078] In this way, the screw 1 of a self-drilling bolt 100 according to the invention makes it possible to fix the first sheet 36 to the second sheet 37, said two sheets 36, 37 being parallel and separated and said screw 1 extending perpendicular to said two sheets 36, 37.

[0079] Referring to Figures 23 and 24, according to two other variant embodiments of a self-drilling bolt 100 according to the invention, said screw 1 comprises a body 2 having a smooth segment 31 and a threaded segment 32 extended by the drill point 3 and the smooth end 4 provided with the two grooves 7, 8. The specificity of these screws 1 is that they comprise projecting fins 40, 41, which can be placed on the smooth segment 31 near the threaded segment 32 as illustrated in [Fig.24], or in an area located between the threaded segment 32 and the drill point 3, as illustrated in [Fig.23]. These fins 40, 41 make it possible to bore a first element which may for example be wood, so as not to burn the wood and / or the screw, when the smooth end 4 comes into contact with the metal support which it must then pierce, especially for significant thicknesses of metal. The fins 40 are designed to break upon contact with said metal support.

[0080] Referring to [Fig.25], according to another alternative embodiment of a self-drilling bolt 100 according to the invention, the screw 1 comprises a groove 38 between the threaded drill point 3 provided with the two grooves 7, 8 and a threaded segment 32 of the body 2 of the screw 1. The drill point 3 and the threaded segment 32 have the same external diameter while the groove 38 has an outside diameter which is smaller than that of said drill tip 3 and said threaded segment 32.

[0081] Referring to Figures 26 and 27, according to an alternative embodiment of a self-drilling bolt 100 according to the invention, the screw 1 comprises a breaking groove 39, which is placed between the threaded body 2 and the drill point 3 comprising the two grooves 7, 8. This groove 39 has the particularity of being of a small diameter compared to that of said threaded body 2 and that of said drill point 3 as illustrated in [Fig.26]. Referring to [Fig.27], once the screw 1 is in its final position in the thickness of material that it has just pierced, said screw 1 can be broken at the breaking groove 39 in order to remove the drill point 3 as well as the smooth end 4. Indeed, said drill point 3 and said smooth end 4 protrude from said thickness of material, and can constitute elements likely to cause injuries.Thanks to the presence of this breaking groove 39, these two elements 3, 4 can be easily removed.

[0082] Referring to [Fig.28], according to another alternative embodiment of a screw according to the invention, the screw 1 comprises a threaded sleeve 42 which is screwed onto the threaded body 2 of said screw 1. In this way, once the screw 1 has pierced the thickness 43 of hard material, said thickness 43 is caught between a nut 200 which is screwed onto the threaded body 2 and said sleeve 42, said nut 44 and said sleeve 42 then being able to exert a clamping pressure on said thickness 43 of hard material. It should be noted that the body 2 emerging from the thickness 43 of hard material is different from that of the threaded body 2 located inside said thickness 43. The sleeve 42 forms the junction between said two bodies 2.

[0083] Referring to [Fig.29], once the screw 1 has pierced a thickness of hard material, an enlarged head 45 of said screw 1 bears against a first face 46 of said thickness, and a nut 200 which is screwed onto the threaded body 2 of said screw 1 bears against a second face 48 of this thickness which is parallel to said first face 46. In this way, a part of the threaded body 2, the drill point 3 and the smooth end 4 protrude from the nut 200.

[0084] Referring to [Fig.30], compared to the configuration described above, as the drill tip 3 is threaded, it is possible, whatever the length of the screw 1, and the thickness of the materials to be drilled, to screw the nut 200 onto the drill tip 3 and to tighten the assembly even though the nut 200 is on the threaded drill tip 3.

[0085] The enlarged head 45 of the screw 1 is always in abutment against the first face 46 of the thickness of material, and the nut 200 which is screwed onto the drill tip 3 of said screw 1 comes into abutment against the second face 48 of this thickness. In this way, only the smooth and conical end 4 of the screw 1 emerges from the nut 200.

[0086] A method of manufacturing a screw 1 of a self-drilling bolt 100 according to the invention comprises the following main steps: - a step of providing a screw blank 1 comprising an enlarged head and a smooth cylindrical shank, - a step of stamping the end of the smooth cylindrical rod to obtain a smooth conical end 4 and the two grooves 7, 8, - a rolling step to obtain a thread on the smooth cylindrical rod to form the threaded drill point 3.

[0087] Such a method may also include a deburring step.

Claims

Claims

1. Self-drilling bolt (100) comprising a self-drilling screw (1) and a nut (200) capable of being mounted on the self-drilling screw (1), said self-drilling screw (1) comprising a body (2) having at least one threaded zone and extended by a drill point (3) provided with a smooth end (4) and of pointed shape, characterized in that the drill point (3) comprises a thread (6) capable of receiving the nut (200) so that said nut (200) can be screwed around said drill point (3).

2. Self-drilling bolt according to claim 1, characterized in that the threaded body (2) and the drill point (3) each have an identical thread (5, 6), said threaded body (2) and said drill point (3) having equal internal diameters.

3. Self-drilling bolt according to claim 1, characterized in that the threaded body (2) has a formed thread (5) and the drill point (3) has a moderately formed thread (6), said threaded body (2) and said drill point (3) having equal internal diameters.

4. Self-drilling bolt according to claim 1, characterized in that the threaded body (2) has a formed thread (5) and the drill point (3) has a weakly formed thread (6), said threaded body (2) and said drill point (3) having an identical internal diameter.

5. Self-drilling bolt according to any one of claims 1 to 4, characterized in that the drill point (3) has at least one groove (7, 8) extending over the entire length of said point (3) and of the end (4), and in that said groove (7, 8) originates at the periphery of a first end of the drill point (3) in contact with the threaded body (2) and extends to a second end corresponding to the end of the end (4).

6. Self-drilling bolt according to claim 5, characterized in that the end (4) of the screw (1) comprises a conical wall and the angle of inclination of said wall defining this end (4) relative to the axis of revolution of the screw (1) is between 10° and 85°.

7. Self-drilling bolt according to any one of claims 5 or 6, characterized in that the edges of said at least one groove (7, 8) in the end (4) are sharp, so that said end (4) defines cutting lips (16, 17) which will promote the drilling of a thickness of material.

8. A self-drilling bolt according to any one of claims 5 to 7, characterized in that the screw (1) has two grooves (7, 8) arranged diametrically opposite each other, and in that said two grooves (7, 8) are separated from each other by being distinct.

9. Self-drilling bolt according to claim 1, characterized in that the end (4) of the screw (1) comprises a widened frustoconical base (18) extended by a conical section (19) ending in a point, and in that the angle of inclination of the frustoconical base (18) relative to the axis of revolution of said end (4) is less than that of the conical section (19) relative to said axis.

10. Self-drilling bolt according to claim 1, characterized in that the end (4) of the screw (1) comprises a widened frustoconical base (18) extended by a conical section (19) ending in a point, and in that the angle of inclination of the frustoconical base (18) relative to the axis of revolution of said end (4) is greater than that of the conical section (19) relative to said axis.

11. Self-drilling bolt according to any one of claims 1 to 10, characterized in that the self-drilling screw (1) comprises a breaking groove (39) so that said screw (1) can be broken at said breaking groove (39) and can no longer constitute a harmful protrusion.

12. Self-drilling bolt according to claim 11, characterized in that the breaking groove (39) is placed between the threaded body (2) of the self-drilling screw (1) and the drill point (3).

13. Self-drilling bolt according to any one of claims 1 to 12, characterized in that the self-drilling screw (1) comprises at least one widening element (40, 41) projecting from an external surface of said screw (1) and intended to widen a hole that said screw (1) will have previously created.

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