WO2022090659A1

WO2022090659A1 - Part made of mineral and/or composite material with a sharp re-entrant angle

Info

Publication number: WO2022090659A1
Application number: PCT/FR2021/051870
Authority: WO
Inventors: Julien BADINANT; Olivier Gomet
Original assignee: Gomet Granit
Priority date: 2020-11-02
Filing date: 2021-10-25
Publication date: 2022-05-05
Also published as: FR3115722A1; FR3115722B1

Abstract

The invention relates to a part (1) made of mineral or composite material having a re-entrant angle cut-out defining two contiguous sections (2a, 2b). According to the invention, the two sections (2a, 2b) belong to a same one-piece portion (2) of the part (1), the two sections (2a, 2b) are connected together by a curve (4) replacing a sharp re-entrant angle so as to prevent incipient ruptures in the material, and the part (1) comprises an added element (3) having, on the one hand, an internal portion that fills a space corresponding to the curve (4) and, on the other hand, an external portion defining a sharp edge of the re-entrant angle.

Description

Part in mineral and/or composite material with sharp re-entrant angle

Technical area

The invention relates to the technical field of the manufacture of objects in mineral material, or in composite material.

In general, the invention relates to the manufacture of parts based on any type of mineral material, such as granite, marble, glass, ceramics, etc. or in composite material with or without mineral filler, or in non-metallic and inorganic material, or more generally in any material in which a sharp re-entrant corner cutout creates incipient fractures.

Prior art

It is known in the field of the manufacture of objects in mineral or composite material from mineral material that it is necessary to avoid producing a one-piece part having a sharp re-entrant angle, that is to say an angle whose measurement on the side of the material is more than 180° and whose edge is not rounded by a fillet.

Indeed, such a zone is a zone of stress concentration and corresponds to a zone of fragility of the part where incipient fractures can be created which can lead to the ruin of the part.

In the particular case of worktops, coming for example to equip a kitchen, when the top has a re-entrant shape, such as an "L" or "U" shape, it is not possible to achieve this shape of "L" or "U" by cutting within a single plate. An “L” shape, for example, is therefore conventionally obtained by assembling two plates. The re-entrant angle of the “L” shape is obtained by assembling these two plates, which then presents a sharp edge. In the case of a sink, it is an "O" shape.

However, this method is not satisfactory because the work plan obtained has an edge between the two plates which is visible and unsightly.

It can be envisaged to make a simple fillet, that is to say an outgoing curve, at the level of the edge of the re-entrant angle, but the aesthetics of the part is degraded because the goal to be achieved is to present a re-entrant angle whose edge is sharp. Disclosure of Invention

One of the aims of the invention is to provide a part made of mineral or composite material from mineral material, having a re-entrant angle in a one-piece part, for example a right angle, without creating any incipient fracture at the level of the vertex of the re-entrant angle.

For this purpose, a part made of mineral or composite material has been developed with two contiguous sides defining between them a re-entrant angle.

According to the invention, the two sides belong to the same one-piece part of the part and are connected to each other by a cutout according to a curve replacing a sharp angle. The part also comprises an added element having, on the one hand, an internal portion which fills a space corresponding to the curve and, on the other hand, an external portion defining a sharp edge of the re-entrant angle.

In this way, the curve replaces the sharp re-entrant angle of the two sides, and therefore eliminates the stress concentration zone of the part. The incipient fractures in the material are therefore minimized. The part then has a re-entrant angle made in a single piece, but the apex of the angle is in fact made without a sharp angle, but rather via a curve. The added element includes the sharp corner and thus gives the illusion of a real sharp re-entrant corner cutout of the one-piece part.

The sharp corner may be present in the added element, but its small size relative to that of the part prevents it from presenting the same fragility and the same disadvantages.

According to a first embodiment, the added element is in a single part. Thus the assembly of the added element on the part is easy.

According to a second embodiment, the one-piece part of the part is in the form of a plate and comprises one or two added overhangs defining a sharp edge of the re-entrant angle, each fixed along a side, not parallel to the plate, that is to say inclined or orthogonal with respect to the plate. In particular, the part can comprise two inserts attached in contact with one another and defining between them a sharp edge of the re-entrant angle. Fallout can be used to achieve a part that looks like a thick part, while achieving savings in mass or material cost. The fallout can also be used to create edges on the sides of the re-entrant angle. The two overhangs define between them a sharp edge of the re-entrant angle, which corresponds to the desired aesthetic. A single fallout can define a sharp edge of the re-entrant angle, for example with the other face of the one-piece part. Possibly contact faces between the sides and the fallout are machined and have an assembly profile, such as a bevel or a rabbet, so as to increase their contact surface and guarantee the solidity and aesthetics of their assembly, or offer more favorable assembly possibilities. The assembly profile can also be a straight cut.

Possibly contact faces between the part at the level of the curve and the added element are machined and present an assembly profile for the same reasons.

In this second embodiment, the insert is preferably in two parts each forming an integral part of one of the fallouts, so as to have only three parts to be assembled instead of four.

In either embodiment, the insert may be in the form of a cured resin or glue, or may be made of the same material as the part. If it is resin or hardened glue, the manufacture of the elements of the part is facilitated since it is not necessary to use machines with several axes or numerical control. If it is an element made of the same material as the part, then the visual uniformity of the assembly is guaranteed.

With the aim of simplifying manufacture, the curve is of the circular, oval or elliptical type and has a radius of between 0.3 mm and 400 mm, and preferably between 0.5 mm and 200 mm.

More specifically, the material is granite, or marble, or glass, or ceramic or even a composite material with or without mineral filler.

The part has an external edge at its inside corner. Preferably, this external edge is machined according to a finishing profile measuring at least 0.5 mm. This not only makes it possible to have a non-cutting edge for the user, but above all to conceal the joint between the one-piece part of the part and the added element.

Advantageously, the finishing profile follows the profile of the curve, so that the one-piece part of the part has absolutely no sharp corners.

The invention also relates to a process for preparing a part according to the invention, with a view to the manufacture of this part, comprising the cutting of a one-piece part with two contiguous sides defining a re-entrant angle, the two sides being connected to each other by a curve replacing a sharp re-entrant angle, and defining a space intended to be filled by an added element in the room.

This preparation process can also comprise the cutting of an added element configured to be assembled on the part, the added element having, on the one hand, a portion internal configured to fill a space corresponding to the curve of the one-piece part and, on the other hand, an outer portion configured to define a sharp edge of the re-entrant angle between the two contiguous sides of the one-piece part of the part.

The invention also relates to a method for manufacturing a part according to the invention, comprising the preparation of the part as mentioned above, followed by the filling of the space corresponding to the curve of the one-piece part between its two sides contiguous by an added element, the added element having, on the one hand, an internal portion configured to fill a space corresponding to the curve of the one-piece part and, on the other hand, an external portion defining a sharp edge of the re-entrant angle between the two contiguous sides of the one-piece part of the part. Typically, the filling of the space corresponding to the curve is done by assembling the added element with the one-piece part.

Brief description of the drawings

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which must be read in conjunction with the appended drawings in which:

- Figure 1 is a perspective view, seen from above, of a part according to one embodiment of the invention;

- Figure 2 is a rear view of a one-piece tray according to the embodiment of Figure 1;

- Figure 3 is a detail view similar to Figure 1;

- Figure 4 is another detail view of a part similar to Figure 1;

- Figure 5 is a detail view of a fallout;

- Figure 6 is a detail view of a part according to another embodiment;

- Figure 7 is a perspective view, seen from above, of a part according to another embodiment;

- Figure 8 is a perspective view, seen from above, of a part according to another embodiment;

- Figure 9 is a perspective view, seen from above, of a part according to another embodiment;

- Figure 10 is a perspective view, top view, of the elements of a part before assembly, according to a possible embodiment of the invention;

- Figure 11 is a perspective view, top view, of the part of Figure 10 after assembly, according to a possible embodiment of the invention; - Figure 12 is a perspective view, top view, of the elements of a part before assembly, according to a possible embodiment of the invention;

- Figure 13 is a perspective view, top view, of the part of Figure 12 after assembly, according to a possible embodiment of the invention.

Detailed description of the invention

Figure 1 illustrates a part 1 in mineral material according to the invention, and in the particular case where it is a worktop. Part 1 can be of any shape or application, it can for example be a vertical panel covering a facade, or any other solid object that the designer wishes to create.

In the particular embodiment illustrated in FIG. 1, part 1 is an “L”-shaped worktop having two contiguous sides 2a, 2b, the two sides 2a, 2b here forming a right re-entrant angle. In this case, the one-piece part 2 is a plate. In the rest of the document, reference will be made to the plate 2 without this limiting the possible embodiments of the one-piece part 2. Thanks to the invention, the work plan is one-piece and has no cutout in the extension of one of the two sides 2a, 2b.

The mineral material can be granite, marble, ceramic or even glass. It can also be a composite material that may or may not include a mineral filler. Composite materials generally consist of a resin ensuring the cohesion of the material, and can be loaded with mineral particles giving part 1 its appearance, as well as improved mechanical properties.

It is recalled that the invention is not limited to re-entrant angles exclusively as right angles, but to all re-entrant angles, i.e. angles whose measurement on the side of the material is more than 180°.

The sharp re-entrant edges constitute stress concentration zones in the material. These areas weaken part 1, and it is common for incipient breaks or cracks to occur at this location, degrading part 1 and possibly leading to its ruin.

Also, part 1 has, at the junction between the two sides 2a, 2b, a re-entrant curve 4, that is to say on the side of the material. This re-entrant curve 4 connects the two sides 2a, 2b, thus eliminating the sharp edge of the re-entrant corner of part 1, and thus prevents the aforementioned drawbacks.

This curve 4 can be circular with a constant radius for example between 0.3 and 400 mm, preferably between 0.5 and 200 mm, and more preferably between 1 mm and 50 mm, such as for example 8 mm. A small radius makes it possible to have a more discreet curve 4 and thus that can be integrated into the chamfer of the edge of the two sides. In the case where the curve 4 is oval or elliptical, its radius varies but its minimum radius is then between 0.3 mm and 400 mm, and preferably between 0.5 mm and 200 mm.

In the case where part 1 is a work surface, it then comprises a plate 2. It may be envisaged to add fallout 5 to it along each side 2a, 2b.

These fallouts 5 are longitudinal elements attached in a non-parallel manner, to the surface of the plate 2, and can be arranged according to two objectives to be achieved.

A first objective is to give part 1 a much greater visual depth. Preferably, the fallouts are fixed orthogonally, but they can also be fixed at an angle, for example of 30° or even 45°, so as to form a slope inclined with respect to the plate 2. However, the use of the fallouts 5 saves material during the manufacture of part 1. Its mass is also limited. This solution is particularly indicated in the case of ceramic-type materials, where the thickness of the plates is limited. The thickness of fallout 5 is not necessarily equal to that of plate 2.

A second objective is that the fallouts 5 constitute the edges of the plate 2. Thus, at the level of the re-entrant angle, said fallouts 5 are in contact with each other and define between them a sharp edge of the re-entrant angle. In this case, the height of the fallouts 5 is generally equal to the thickness of the plate 2. Depending on the desired configuration, the height of the fallouts 5 may be different from the thickness of the plate 2, for example the fallouts 5 may exceed slightly the upper surface of the plate 2, in order to create a water retention zone for example. The thickness of fallout 5 is not necessarily equal to that of plate 2.

Attachment 3 can be part of a single spinoff 5, or be in two parts each forming an integral part of one of the spinoffs 5.

Conventionally, the fallouts 5 are fixed by gluing to the part 1. For this purpose, it is possible to machine, for example in the form of a bevel, the contact surfaces between the faces 2a, 2b and the fallouts 5, as illustrated in Figures 2 and 3. Without departing from the scope of the invention, this machining can take the form of any assembly profile, such as a tab, a rebate or a molding. The contact surfaces between the fallouts 5 themselves can also be machined and have an assembly profile.

A finishing profile 8 such as a chamfer or a rounding can also be made on the external edge of the part 1. This finishing profile 8 measuring at least 0.5 mm makes it possible to "break the angle" external to the part 1, which avoids both having a cutting angle which could injure the user; and which makes it possible to reduce the fragility of the outer edge during the life of the part 1. This finishing profile 8 also makes it possible to remove the bonding burrs, and possibly to conceal the bonding joint linked to the radius of the curve 4. In addition, if bas-relief moldings are present on the overhangs 5, then the moldings are connected to the finishing profile 8 so that there are no discontinuities between them.

At the edge of the re-entrant corner, this finishing profile 8 can be joined in different ways illustrated in figures 4 and 6:

- or by following the radius of curve 4 as shown in figure 6. Thus, the finishing profile 8 does not have a sharp re-entrant corner. This solution is the most reassuring with respect to the stress concentrations, but can be considered as being a defect in the appearance of part 1;

- either by including a sharp corner edge as shown in figure 4. The sharp re-entrant corner is only present at the level of the finishing profile 8, that is to say on a limited portion of the part 1. Thus, the stress concentrations remain limited, which does not harm the strength of part 1, and the aesthetics of part 1 is improved.

FIG. 4 illustrates that for aesthetic purposes, and in order to give the illusion of a sharp-edged cutout, the re-entrant curve 4 is filled by an added element 3. This added element 3 can be of different natures and of different designs. , in one part or in several parts.

It can first be simply a glue or a resin, if possible having a similar appearance to the material of part 1 once hardened. In this way, it is not necessary to first manufacture an additional element, the geometry of which is complex. In this case, it may be judicious to produce a re-entrant curve 4 with a small radius, for example with a radius of 8 mm or less. Thus, the volume to be filled by the glue is limited.

As illustrated in Figures 7, 8, 9, and 10, the added element 3 can also be a kind of key, for example in the shape of a % of round or any other solid of revolution such as a cylinder. This solution is particularly suitable in cases where the part 1 does not have fallout and is of limited thickness, for example less than 50mm; as well as in cases where the fallouts 5 are assembled to the plate 2 with an assembly profile which is a rabbet. It is obvious that even if the profile of the internal portion of the added element 3 must correspond to that of the curve 4, it is not necessarily identical so that a functional play allows the assembly of the added element 3 , and leaves plenty of room for glue. In the case where the part 1 comprises fallouts 5, the added element 3 can also be an integral part of a single fallout or of both fallouts 5. It can be part either of only one of the fallouts 5, or be in two parts each of which is an integral part of one of the two spin-offs 5.

In the preferred embodiment where Part 1:

- includes a tray 2;

- includes spinoffs 5;

- That the contact surfaces between the sections 2a, 2b and the fallout 5 are bevelled;

- that at the re-entrant curve 4, the contact surfaces between the one-piece part 2 and the insert 3 are also bevelled;

- and that the added element 3 is in two parts each forming part of a fallout 5; then said fallouts 5 have the form illustrated in Figure 5.

It can be seen that the fallout 5 comprises a first bevel 6 intended to bear against a homologous bevel of a face 2a or 2b of part 1; as well as a second bevel 7, of curved shape and similar to that of the re-entrant curve 4, so that the assembly of the two fallouts 5 with the part 1 leaves only a minimum of space between the parts, which is particularly visible in Figure 4.

Thanks to the bevels, the contact surfaces between the parts are increased, which allows a better resistance of the assembly by gluing. Note, however, that it is not always necessary to form an assembly profile. In particular, when a mortar holds the one-piece piece 2 and the added element 3, it is not necessary to improve the contact between the one-piece piece 2 and the added element 3. This is particularly the case when the piece 1 is a tile or cobblestone, typically to form a floor or wall covering, the added element 3 is only assembled to the one-piece part to fill the space corresponding to the curve 4 and to define a sharp edge of the angle falling between the two sides. The assembly is then ensured by the mortar.

We see in Figure 2 that the presence of the assembly profiles on the plate 2, here bevels, is mainly visible on the underside of the part 1. Logically, in the case of a bevel for example at 45 ° , the radius of the bevel on the underside of the plate 2 corresponds to the radius of the re-entrant curve 4 plus the thickness of the plate 2.

With preferred values of a re-entrant curve 4 with a radius of 8mm, a plate thickness 2 of 12 mm and in the case of a 45° bevel, then the radius of the bevel on the underside of the plate 2 is 20 mm . However, the upper face of plate 2 does not present a re-entrant curve 4 of only 8 mm, which does not unduly impact the visual appearance of the re-entrant angle of the part 1 and further promotes the illusion of a sharp re-entrant angle.

Figure 7 illustrates an embodiment in which there are no fallouts 5. The added element 3 is a key which fits into the curve 4.

FIG. 8 illustrates an embodiment where the assembly profile between the overhangs 5 and the plate 2 is a rebate made so that the external edge of the part 1 is that of the plate 2. The assembly profile between the two fallouts 5 is a bevel. In the mode illustrated, the added element 3 is not integrated with the spin-offs 5 and here takes the form of a key, which is assembled by gluing with the plate 2 and the spin-offs 5.

FIG. 9 illustrates another embodiment, in which the assembly profile between the overhangs 5 and the plate 2 is a rebate made in the other direction than that shown in FIG. 8. Here, the external edge of the part 1 is that of the fallouts 5 and of the added element 3. In this particular embodiment, the curve 4 is not inward but outward and takes the form of a fillet. However, the assembly between the plate 2, the drops 5 and the added element 3 will give part 1 the appearance of a sharp angle, without part 1 being weakened.

Furthermore, part 1 can be shaped differently from Figures 1 to 9 without departing from the scope of the invention, which is defined by the claims. In particular, part 1 can be shaped differently from a worktop, and can be of any type suitable for the present application. Curve 4 can be inward or outward, depending on the assemblies and finishes provided.

In addition, the technical characteristics of the various embodiments and variants mentioned above can be, in whole or for some of them, combined with each other. Thus, part 1 can be adapted in terms of cost, functionality and performance.

A description will now be given of examples of the process for manufacturing part 1 and its constituents. A first step consists in preparing the elements of the part 1, which includes the cutting of a one-piece part 2 with two contiguous sides 2a, 2b defining a re-entrant angle, the two sides 2a, 2b being connected to one another. another by a curve 4 replacing a sharp re-entrant angle. The one-piece part 2 is obtained by cutting out a larger part, for example a plate or a slice, in mineral or composite material, so as to define at least two contiguous sections 2a, 2b connected by the curve 4. cuts out any operation allowing to separate two solid portions of the same solid material, as well as its result. The term cutting can therefore also mean sawing, machining, cutting, slicing, etc., and is opposed to operations such as molding. When cutting the one-piece part 2, the faces 2a, 2b of said one-piece part 2 can be cut by following a machining profile such as bevel, chamfer, straight, rebate, etc., the machining profile having a curve 4 connecting the two sections 2a, 2b, in the angle formed by the junction of the two contiguous sections 2a, 2b. Preferably, the contiguous sections 2a, 2b are rectilinear. The edge of the one-piece part 2 can also have a machining profile as mentioned at the level of the curve 4, different or similar to the machining profile of the sections 2a, 2b or the fallouts.

If the part 1 includes one or more fallouts 5, these are also cut out in the same way as the one-piece part 2. The fallouts are cut out with a machining profile compatible with the machining profile of the sections 2a, 2b and optionally with the machining profile of spoke 4. Drops 5 can also be machined to be mutually compatible, at their contact zone, to define between them a sharp edge of the re-entrant angle. For example, the fallouts 5 can be bevelled at their contact.

Fallouts 5 can be cut so as to present an internal portion filling a space corresponding to curve 4 and, on the other hand, an external portion defining a sharp edge of the re-entrant angle. In other words, spinoff 5 can include topper 3, especially with a portion of topper 3 on every topper 5.

Added element 3 can be distinct from fallout 5, especially in the absence of the latter. The added element 3 is then cut according to the same methods as the one-piece part 2. In all cases, the added element 3 is cut so that its cutting profiles (of the bevel, chamfer, straight, etc.) allow assembly with the one-piece part 2 and/or the fallouts 5 so as to obtain the desired part 1. On the one hand, the machining profile of the added element 3 must marry the zone of the one-piece part 2 having a curve 4, and on the other create the sharp edge of the re-entrant angle which connects the sections 2a , 2b. It should be noted that this sharp edge can also be created in a second step after assembly and gluing of the elements of part 1 together, for example during the shaping of the finishing profile 8 and/or the machining of the edges. If there are dropouts 5, the profiles of the cutouts of the added element 3 must also be compatible with the dropouts 5.

It is recalled that the added element 3 can be in the form of a resin or a hardened glue. In this case, there may be no cutting to obtain the added element 3, but a formation of said added element 3 directly against the curve 4, the material coming to fill the space corresponding to the curve 4, and then being shaped to present an outer portion defining a sharp edge of the re-entrant angle.

Once the elements of the part 1 have been obtained during the preparation, including at least the one-piece part 2, the space corresponding to the curve 4 is filled by adding the added element 3. In particular, the insert 3 can be assembled to the part monobloc 2 and/or to the fallouts 5. The assembly of the part 1 can be carried out by any method making it possible to carry out a definitive fixing of the elements together, in particular by gluing the elements together. He can then proceed with the production of a finishing profile 8 to remove the excess glue, and improve the concealment of the presence of the added element 3.

Figures 10 to 13 illustrate examples supplementing those already illustrated by the other figures, and are used to give non-limiting examples of manufacture. The details given in one embodiment can be applied to the other embodiments if they are technically relevant. The dimensions are given for information only.

In the example of figure 10, part 1 comprises the one-piece part 2, an added element 3, and drop-offs 5, assembled with rebate and bevel. The preparation of part 1 therefore includes obtaining these elements. In a slice or a plate of any shape made of mineral and/or composite material, the sections 2a, 2b are cut following a machining profile of the straight type (90°) with a radius of curvature 4 of 8 mm on the upper and visible part of the plate, returning 2.7 mm on a first side 2a and 2.7 mm on a second side 2b, in the angle formed by the junction of the two contiguous sides 2a, 2b. In curve 4 with a radius of 8 mm, the cut is also made with a 90° straight type machining profile. If in this example, the rabbets 9 are made with a straight-type machining profile, it can also be considered to make rabbets 9 with a non-straight profile, for example curved or inclined, in order to minimize the onset of breakage in the material.

The sides 2a, 2b are machined following a rebate type machining profile 9 of a width corresponding to the thickness of the fallouts 5 plus 1mm and of a depth that can allow 4 mm of material to be left in this zone for a finishing profile 8. In the machined part of the rebate 9 (not visible) at the junction of the two sides 2a, 2b, the rebate is preferably machined always of the same thickness along a radius which corresponds to 1.55 times the fallout thickness plus 1 mm.

Fallouts 5 are prepared by cutting them out of a slice or plate of mineral and/or composite material. Fallouts 5 are cut with a machining profile 6 of the bevel type, for example at 46°. The contact face between the two overhangs 5 can also be cut according to a bevel type assembly profile.

The preparation of the added element 3 comprises the cutting, in a slice or plate, of any shape in mineral and/or composite material, in a single part in the form of a cylinder 15.9 mm in diameter , from which we subtract a volume of square section with a side of 14 mm and whose center of this square is displaced by 1.7 mm with respect to the center of the cylinder along the axes of the sides 2a, 2b, which allows on one side to follow the curve of the one-piece part 2, and on the other creates the sharp edge of the re-entrant angle which connects the sides 2a, 2b. It is also possible to subtract the excess volume when making the finishing profile 8.

The one-piece part 2, the added element 3, and the fallouts 5 are assembled to obtain the part, as illustrated in FIG. 11, by gluing or any other process making it possible to obtain a definitive fixing of the elements between them.

In the example of Figure 12, the part 1 comprises the one-piece part 2 and fallouts 5 integrating the insert 3, assembled in a bevel. Preparing Exhibit 1 therefore includes first obtaining these elements. In a slice or a plate of any shape made of mineral and/or composite material, the sections 2a, 2b are cut following a machining profile of the 46° bevel type with a curve 4 of the outgoing type of radius 8 mm, in the angle formed by the junction of the two contiguous sections 2a, 2b. In curve 4 of 8 mm, the cut is also made with a 57° bevel type machining profile.

Fallouts 5 are prepared by cutting them out of a slice or plate of mineral and/or composite material. Fallouts 5 are cut with a machining profile 6 of the bevel type, for example at 46°. The contact face between the two overhangs 5 can also be cut according to a bevel type assembly profile. In this example, the added element 3 is an integral part of the fallouts 5. Before the assembly between them of the two fallouts 5, the added element 3 is in two parts, one for each fallout 5, and which are joined during the 'assembly. To form the added element 3, the upper angle of the fallouts 5 is rounded to match the curve 4 on the internal side, while the external side defines, between the fallouts 5, a sharp edge of the re-entrant angle between the two sides 2a, 2b contiguous to the one-piece part 2.

The one-piece part 2 and the fallouts 5 including the added element 3 are assembled to obtain the part 1, by gluing or any other method making it possible to obtain a definitive fixing of the elements together, as illustrated in FIG. 13. During the assembly, the bevels of the fallouts 5 are assembled against the bevels of the faces 2a, 2b of the one-piece part 2, so that the bevels of the fallouts 5 protrude from the upper surface of the one-piece part 2 by 2.7 mm, ensuring the covering the upper part of the sections 2a, 2b, as well as the curve 4. Once the assembly has been carried out, a finishing profile 8 of the chamfer type of 2.7 mm (i.e. 2.7 mm by 2.7 mm) minimum is carried out on the edges of the bevels of the fallouts 5, in order to remove the material protruding from the upper surface of the one-piece part 2 beyond the sections 2a, 2b. The invention is not limited to the embodiment described and shown in the appended figures. Modifications remain possible, in particular from the point of view of the constitution of the various technical characteristics or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

Claims

1. Part (1) in mineral or composite material having a re-entrant angle cut defining two contiguous sides (2a, 2b), characterized in that the two sides (2a, 2b) belong to the same one-piece part (2) of the piece (1), the two sides (2a, 2b) are connected to each other by a curve (4) replacing a sharp re-entrant angle so as to avoid incipient fractures in the material, and in that the part (1) comprises an added element (3) having, on the one hand, an internal portion coming to fill a space corresponding to the curve (4) and, on the other hand, an external portion defining a sharp edge of the angle returning.

2. Part (1) according to claim 1, wherein the insert (3) is in a single part or the insert (3) is in several parts.

3. Part (1) according to any one of the preceding claims, in which the one-piece part (2) is in the form of a plate and the part (1) comprises one or two added drops (5) defining an edge sharp of the re-entrant angle, each fixed along a side (2a, 2b), and inclined or orthogonal with respect to the plate (2).

4. Part (1) according to any one of the preceding claims, wherein:

- contact faces between the part (1) at the level of the curve (4) and the added element (3) are machined and have an assembly profile, such as a bevel, a rabbet, or a straight cut , and or

- the part (1) comprises one or two added overhangs (5) defining a sharp edge of the re-entrant angle, each fixed along a face (2a, 2b), and inclined or orthogonal with respect to the plate (2) , and the contact faces between the sections (2a, 2b) and the drops (5) are machined and have an assembly profile, such as a bevel, a rabbet, or a straight cut.

5. Part (1) according to any one of claims 3 to 4, wherein the part (1) comprises two inserts (5) attached being in contact with one another and defining between them a sharp edge of the re-entrant angle.

6. Part (1) according to any one of claims 3 to 5, wherein the insert (3) is in two parts each forming an integral part of one of the fallouts (5), or the insert ( 3) is in a single part and is an integral part of a single fallout (5).

7. Part (1) according to any one of the preceding claims, in which the added element (3) is a resin or a hardened glue, or is made of the same material as that of the part (1).

8. Part (1) according to any one of the preceding claims, in which the curve (4) is of the circular, oval or elliptical type and has a radius of between 0.3 mm and 400 mm.

9. Part (1) according to any one of the preceding claims, in which the material is of the mineral type, such as a ceramic, or the material is of the composite type.

10. Part (1) according to any one of the preceding claims, said part having an outer edge at its inside corner, the outer edge is machined according to a finishing profile (8) measuring at least 0.5 mm.

11. Part (1) according to any one of the preceding claims, wherein the finishing profile (8) follows the profile of the curve (4).

12. Part (1) according to any one of the preceding claims, in which the curve (4) is of the outgoing type or of the reentrant type.

13. A method of preparing a part (1) according to any one of the preceding claims, comprising the cutting of a one-piece part (2) with two contiguous sides (2a, 2b) defining a re-entrant angle, the two sides ( 2a, 2b) being connected to each other by a curve (4) replacing a sharp re-entrant angle, and defining a space intended to be filled by an added element (3) in the part (1).

14. Preparation process according to the preceding claim, further comprising the cutting of an added element (3) configured to be assembled on the part (1), the added element (3) having, on the one hand, a portion internal configured to fill a space corresponding to the curve (4) of the one-piece part (2) and, on the other hand, an external portion configured to define a sharp edge of the re-entrant angle between the two contiguous sections (2a, 2b ) of the one-piece part (2) of the part (1).

15. A method of manufacturing a part according to any one of claims 1 to 12, comprising the preparation of the part (1) according to any one of the two preceding claims, followed by the filling of the space corresponding to the curve (4) of the one-piece part (2) between its two contiguous sides by an added element (3), the added element (3) having, on the one hand, an internal portion configured to fill a space corresponding to the curve (4) of the one-piece part (2) and, on the other hand, an outer portion defining a sharp edge of the re-entrant angle between the two contiguous sides (2a, 2b) of the one-piece part (2) of the part ( 1).