EP1660287A2

EP1660287A2 - Hydraulic binder-based, tapered-edge boards, production method and production line therefor, and light work construction method

Info

Publication number: EP1660287A2
Application number: EP04742805A
Authority: EP
Inventors: Paul Jallon; Jean-Louis Laurent; Frédéric Peronnet; Roger Arese; Lionel Zbinden; Emmanuel Vial; Loic Martin
Original assignee: Lafarge Platres SA
Current assignee: Etex France Building Performance SA
Priority date: 2003-08-25
Filing date: 2004-05-21
Publication date: 2006-05-31
Also published as: US20090301630A1; DE202004008232U1; NL1026251A1; ITTO20040335A1; EG24290A; GB2405416A; FR2866369B1; NL1026251C2; JP2007503334A; CA2536971A1; AU2004274198B2; GB2405416B; NZ545333A; BRPI0413388A; BE1016021A3; CA2536971C; WO2005028171A3; FR2860017A1; RU2006109198A; US8257525B2

Abstract

The invention relates to a novel plasterboard and to the production methods thereof. According to the invention, the novel board is designed such that: one face comprises two first parallel tapered edges, while the other face thereof comprises two second parallel tapered edges which are perpendicular to the first; or one face comprises two first parallel tapered edges, while the same face or the other face comprises two second parallel tapered edges which are perpendicular to the first, said second parallel tapered edges having a width of between 100 and 200 mm; or, alternatively, one face comprises two first parallel tapered edges, while the same face or the other face comprises two second parallel tapered edges which are perpendicular to the first, said second parallel tapered edges having a width such that the ratio of the width thereof to the width of the first parallel tapered edges is between 1.5 and 5.

Description

HYDRAULIC BINDER PLATES WITH TINNED EDGES, METHOD FOR MANUFACTURING HYDRAULIC BINDER PLATES AND LINE FOR PRODUCING SUCH PLATES, AND METHOD FOR CONSTRUCTING SECOND WORK

The invention relates to a method for manufacturing plates based on hydraulic binder and a production line for plates based on hydraulic binder using this apparatus. The invention also relates to a new plasterboard having a particular geometry.

US Patent No. 4,781,558 describes an apparatus for the manufacture of plasterboard with recesses. It therefore proposes to produce, on a preform intended to be cut to give plasterboard, recesses by means of a drum 34 comprising bumps 36 (see in particular Figure 1 of this patent). The depth of the hollows is therefore determined by the size of the bumps. Thus, to change the depth and / or the shape of these recesses, the drum 34 should be replaced by another drum having bumps of different size and / or shape (s). This document is particularly intended for the realization of a particular surface condition of the plasterboard; there is no mention of any particular application for producing an imprint in the form of a thinned transversely with respect to the axis of the plate, on the back of the latter (namely the face here upper). In American patent n ° 2 991 824, impressions 51A, 51B are made in a preform intended to be cut to give plasterboard, by means (see in particular FIG. 1 and column 3, lines 29 to 43 of this patent ) of a band 20 rotating around two rollers 21 and comprising a protuberance 25. The preform is then cut in the middle of the indentations so as to produce plates with thinned ends or transverse thinned edges. In US Patent No. 2,246,987, impressions are made in a preform intended to be cut to give plasterboard, by means (see in particular Figures 1 and 1) of a strip 20 having a plurality of protrusions 23 38. In one embodiment, impressions are made on both sides of the plate at the same time. In this case too, to change the dimensions and / or the shape of the imprints, it would be necessary to replace the strip 20 by another strip having protuberances of different size and / or shape (s). The invention aims to solve the problem of making imprints in a preform while offering the possibility of easily and quickly changing the size and / or the shape of these imprints. The invention also aims to solve the problem of making impressions in a preform, according to a method generally of the type described in American patent n ° 2 991 824, allowing the realization of thinned ends or transverse thinned edges so satisfactory.

The invention therefore provides a new hydraulic binder plate with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and on the other face two other thinned ends or parallel transverse thinned edges (25a). perpendicular to the first. The invention also provides a new plate by hydraulic bonding with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and either on the same face or on the other face two second parallel thinned edges ( 25a) perpendicular to the first, said other parallel thinned edges (25a) having a width of between 100 and 200mm. The invention also provides a new plate by hydraulic binder with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and either on the same face or on the other face two second parallel thinned edges ( 25bis) peφendicular to the first, said second parallel tapered edges (25bis) having a width such that the width ratio of said second parallel tapered edges (25bis) to the width of said first parallel tapered edges (10) is between 1.5 and 5. L The invention also provides a method of constructing a finishing work using this plate, as well as a method and a device for manufacturing this plate. The invention also provides a method and devices for manufacturing hydraulic binder plates having four thinned edges on the same face. More specifically, the invention uses in particular an apparatus for producing an imprint or reservation on a preform based on hydraulic binder. This device therefore comprises at least: - a frame; - two first pulleys supported at a first end of the frame and two second pulleys at a second end of the frame; the first pulleys and second pulleys being in parallel planes; the pulleys facing each other being identical; - two transmission belts respectively surrounding the first pulleys and the second pulleys; - At least one wire removably attached to the belts and extending between these belts, so that its longitudinal axis is parallel to the axis of rotation of the pulleys. With this device, it therefore suffices simply to detach the removable means and to replace them with others having a different dimension and / or shape (s) to modify the dimension and / or the shape of the imprints made in the preform. In addition, the use of such an apparatus makes it possible to easily vary the spacing between two cavities and therefore the length of the plates. The invention also relates to a method of manufacturing a plate based on hydraulic binder from a preform intended to be cut, this method comprising a step during which one carries out, by means of an apparatus according to the invention, an imprint in the preform.

This method has the particular advantage of making it possible to obtain plates with thinned edges, a plate in which the transverse thinned edges can be on the same side as the conventional thinned edges or on the opposite side. Finally, the invention further relates to a production line for plates based on hydraulic binder from a preform comprising a facing material covered with a composition of hydraulic binder and supported by a conveyor belt.

(or forming strip). This production line also has the advantage of allowing the production of plates with thinned edges. Other characteristics and advantages of the invention will now be described in detail in the description which follows and which is given with reference to the figures, in which: - Figure 1 shows schematically and in perspective, the apparatus according to invention; - Figure 2 shows schematically and in section the assembly of a wire on a chain link; - Figure 3 shows schematically a wire clamp axis; - Figure 4 shows schematically and in top view a support piece mounted on a chain link; - Figure 5 shows schematically the support piece of Figure 4 in front view; - Figure 6 schematically shows a step in a method of manufacturing plates based on hydraulic binder; FIG. 7 schematically represents another step of a method for manufacturing plates based on hydraulic binder; FIG. 8 represents a plate which can be obtained with the method according to the invention; FIG. 9 shows another plate which can be obtained with the method according to the invention; FIG. 10 illustrates an optional intermediate stage of a method for manufacturing plates based on hydraulic binder; FIG. 11 shows schematically and in perspective, part of the production line for sheets based on hydraulic binder; Figure 12 shows schematically and in top view, a device for the introduction of slats in a preform based on hydraulic binder; Figure 13 shows schematically and in "side view, the device of Figure 12; Figure 14 shows schematically and in side view a variant of the device of Figure 12; Figure 15 shows schematically and in section, a detail of the device of FIG. 12 illustrating the introduction of a slat under a preform based on hydraulic binder; FIG. 16 schematically represents part of a production line for plates based on hydraulic binder according to the invention; and FIG. 17 schematically represents a secondary forming device; FIG. 18 schematically represents a variant of a secondary forming device; FIG. 19 schematically represents a plate in hydraulic binder according to the invention; FIG. 20 schematically represents the plate of FIG. 19 with a change of position of the faces. FIG. 21 schematically represents a plate in hydraulic binder according to the invention sel there is a second embodiment; FIG. 22 schematically shows in section a thinned edge of a plate according to the invention; FIGS. 23A and 23B represent a diagram of the "turning over" of the thinned edges of a plate according to a first embodiment; FIGS. 24A, 24B and 24C represent a diagram of mounting plates with four thinned edges according to the prior art; FIGS. 25A, 25B and 25C represent a diagram of mounting plates with four thinned edges according to the invention. DETAILED PRESENTATION OF THE INVENTION APPARATUS ACCORDING TO THE INVENTION The apparatus according to the invention is shown diagrammatically in FIG. 1. It comprises a frame 101 which is in the shape of an H, but to which the person skilled in the art could easily give many other forms. On this frame 101 are supported, at a first end 104, two first pulleys 102 and 103 and, at a second end 107, two second pulleys 105 and 106. The first pulleys 102,103 are in a foreground, the second pulleys 105,106 in a second plane and the first plane is parallel to the second plane. The pulley 102 and the pulley 105 are of the same dimension and located one opposite the other. The pulley 103 and the pulley 106 are also of the same dimension and located one opposite the other. The pulleys 102, 103, 105 and 106 can turn on themselves. A first transmission belt 10O surrounds the first pulleys 102,103 and a second transmission belt 109 surrounds the second pulleys 105,106. The transmission belts 108 and 109 are identical. They are connected to each other by at least one wire 111. This wire 111 is removably attached to the first and second belts

108,109 and in such a way that its longitudinal axis is parallel to the pulley rotation tax. Thus, when one of the pulleys, for example the pulley 102, turns, it drives the transmission belt 108 which itself drives the other pulley situated in the same plane as it (the pulley 103) as well as the form means elongated 110. The latter then moves along the defined path, on the one hand, by the loop constituted by the belt 108 and, on the other hand, as it is connected to the second belt 109, also by the loop constituted by this last. The symmetry of the apparatus according to the invention therefore allows the axis of the wire 111 to move along an ellipse, its axis remaining constantly parallel to that of the pulleys. It can be provided that two pulleys located one opposite the other are fixed on the same shaft. The apparatus may also comprise means for driving in rotation one at least of the pulleys. These means can possibly drive two pulleys by means of the shaft on which they are mounted. The wire 111 generally has a cylindrical shape, but it can take a large number of shapes among which mention may be made of parallelepipedic, prismatic shapes, the shape of a plate, etc. It can be fixed for example by screwing on the transmission belts so that it can be unscrewed and easily replaced by another means of elongated shape. According to a preferred embodiment of the invention, several wires 111 are arranged parallel to each other, along the transmission belts 108 and 109 (see Figure 1) and fixed in a removable manner. They are preferably spaced from each other. The pulleys are preferably toothed wheels and the transmission belts of the chains can cooperate with these toothed wheels. The wires can then be fixed as illustrated in FIG. 2. In this FIG. 2, one can see a wire 111 held on a chain link 112 by means of a support piece 113 and a wire clamp axis 114. The latter replaces, in the chain link 112, one of the roller carrying axes conventionally used. The wire clamp axis 114 is shown in detail in FIG. 3. It comprises, in order: - a threaded end 115, - a generally cylindrical and smooth part 116, capable of being introduced into the roller of the chain link 112 with a view to replacing the roller-holder axis conventionally used, a smooth part also generally cylindrical and smooth 117, of diameter generally greater than that of the part 116 and capable of being introduced into the bore 118 of the support part 113 ( see Figures 4 and 5), - a head 119, and - a central bore 120 generally machined from the head 119, which can extend to the part 116 and intended to receive the wire 111. The support piece 113 is visible in Figures 2,4 and 5. It includes the bore 118 adapted to cooperate with the corresponding part 117 of the wire clamp axis 114 and a bore 121 opening into the bore 118. This bore 121 is threaded so as to that we can screw a pre screw ssion 122 intended to compress the wire 111 present inside the bore 118 in order to hold it firmly (see FIG. 2). Thus, to fix a wire 111 on the chain link 112, the assembly of FIG. 2 is carried out. For this, it suffices to introduce the part 117 of Tax wire clamp 114 in the support piece 113, to remove Tax normal roller carrier of the link 112, to introduce in Taxe of the roller the part 116 of the thread clamp axis 114, to tighten the assembly by aiming a nut 123 on the end 115 of Tax thread clamp 114, d introduce the wire 111 into the central bore 120 of the wire clamp 114 and hold it there firmly by screwing the pressure screw 122 into the threaded bore 121 until it effectively compresses the wire 111. Of course, the wire clamp axis 114 is mounted so that its head 119 is on the inside of the chain, that is to say facing the other chain. The support piece 113 preferably comprises two pairs (hole 118, threaded bore 121), the spacing between the axes of the holes 118 corresponding to the normal spacing between the axes of the rollers of a chain link 112, so that that two wires 111 can be held on the same link 112, as can be deduced from FIGS. 4 and 5. By thus arranging several identical support pieces 113 on neighboring links, it is possible to align several wires 111 in parallel so as to constitute the elongated means. Another known device could be used for making the imprints, for example that which is the subject of US Patent No. 2,991,824.

PROCESS ACCORDING TO THE INVENTION The apparatus according to the invention can be used, in a method of manufacturing plates based on hydraulic binder, to make an imprint in the preform intended to be cut to give the plates based on hydraulic binder. The preform is then preferably cut at the level of the impression or opposite the place where this impression was made (that is to say on the other face of the preform). The apparatus according to the invention can be used in a process for manufacturing plasterboards with thinned edges. Such a process is illustrated in FIGS. 6 to 10. It comprises the following steps: 1) a hydraulic binder composition (2) is poured onto a facing material (1) supported by a conveyor belt (7) so as to obtaining a preform (5), then a batten (6,23) whose length is at least approximately equal to the width of the preform (5) is introduced under the preform (5); 2) the hydraulic setting of the hydraulic binder composition (2) is allowed to take place (2) and said slat (6,23) is removed; 3) the prefoπne (5) is cut at the level of the thinning (8) created by the slat (6,23). This method of manufacturing plates based on hydraulic binder and with thinned edges will now be described in detail with reference to FIGS. 6 to 15. Next, the use of the apparatus according to the invention in this method will be described. First of all, it is specified that by "transverse edges" is meant in the present description the edges perpendicular to the direction of movement of the conveyor belt in a production line for plates based on hydraulic binder. Such transverse edges are also called "plate ends". Referring to FIG. 6, there is seen a production line for plates produced by casting on a facing material 1 of a composition of hydraulic binder 2 and, generally, covering with a second facing material 3. The passage of the 'together under the forming plate 4 gives a preform 5. The hydraulic binder composition preferably comprises plaster. The facing materials 1 and 3 may consist of sheets of paper or cardboard, glass mats or any material known to those skilled in the art as being able to serve as facing material. After the exit of the preform 5 from under the forming plate (in English "forming plate") 4 or from under the equivalent device used in the production line (for example, a forming roller called in English "master roll") , a slat 6 is introduced between the preform 5 and the start of the conveyor belt 7. The distance between the forming plate 4 and the start of the conveyor belt 7 is such that the preform 5 has not yet had time to harden substantially and still has great plasticity. The introduction is carried out in such a way that the longitudinal axis of the slat 6 is substantially perpendicular to the direction of movement of the conveyor belt 7. The slat 6 is then driven by the conveyor belt 7, just like the preform 5. The hydraulic outlet and the hardening of the plaster composition 2 is then carried out throughout the displacement of the preform 5, designated by the arrows A. Preferably, the withdrawal of the slat 6 takes place before the cutting of the preform 5. Thus, after a certain time, to which corresponds a distance traveled by the preform 5 on the conveyor belt 7, which a person skilled in the art knows how to determine as a function of the speed of movement of the conveyor belt 7 and the setting time of the plaster composition 2 , the hardness of the preform 5 is sufficient so that the lath 6 can be removed without deforming the preform 5 and without the plaster composition 2 coming to fill the space or thinning 8 (FIG. 7) left by the removal of the batten 6. The withdrawal of the batten 6 can be carried out according to any suitable material. For example, when the length of the slat 6 is greater than the width of the preform 5, the slat 6 protrudes relative to the preform 5, and it can then be quickly removed in a direction substantially perpendicular to the direction of movement of the conveyor belt 7 and away from it. This withdrawal action is illustrated by the arrow B in Figure 6. The withdrawal of the slat 6 can also occur by the fall of this slat 6 in the space between two rollers constituting the conveyor belt system which, in general , is not continuous throughout the production line, but is formed by several belts driven by rollers between which there are free spaces. After the removal of the slat 6, the preform 5 continues to move, still driven by the conveyor belt 7 and the hardening of the plaster composition 2 continues. As can be seen in Figure 7, when the thinning 8 arrives at the cutting device generally consisting of a roller provided with a knife 9, it starts and cuts the preform 5. This gives a plate 9a, visible in FIG. 8, the length of which is defined by the distance traveled by the conveyor belt between two cutting operations, that is to say, according to the invention, by the distance traveled by the conveyor belt between two consecutive thinning operations 8. This plate 9a therefore has two thinned transverse edges 10. Preferably, the cutting device is adjusted so that the knife 9 cuts the preform 5 approximately in the middle of the thinning operation. each thinning 8 depends on the dimensions of the slat 6. The latter is generally a parallelepiped whose thickness is generally between 0.5 and 4 mm, preferably between 1.5 and 4 mm. Its width is generally between 5 and 20 cm and its length is at least approximately equal to the width of the preform 5 (possibly reduced by the width of the longitudinal "tape" bands present if necessary), but in general greater in order to be able grasp it to remove it from under the preform 5. In addition, it is desirable that the slat 6 be of a length greater than the width of the preform 5, so as to project from it, which can facilitate its removal. The material of the slats 6 does not matter, as long as it allows these slats to resist the weight of the thickness of preform 5 which is located above each slat 6. It can therefore be a plastic material, wood , metal, etc. with good wear resistance and stability over time. Preferably, the process which has just been described comes in addition to a known process for manufacturing plasterboards having two thinned longitudinal edges. The latter generally provides for the installation of a strip, generally made of plastic, generally called a "tape", on each longitudinal side of the conveyor belt 7. Such a process is described, for example, in European patent application No. 482 810. This therefore makes it possible to obtain a plate based on hydraulic binder 11 as illustrated in FIG. 9, having, in addition to its two thinned transverse edges 10, two longitudinal thinned edges 25, ie in total four thinned edges. It goes without saying that if the frequency of the cutting operations is double that of the introduction of the slats 6, plates are obtained having 3 improved edges (two longitudinal and one transverse). The length of the plasterboard produced depends, of course, on the speed of movement of the conveyor belt and the frequency of the cutting operations. The frequency of the cutting operations is generally directly related to the frequency of insertion of the slats, since it is generally sought to obtain plates having two thinned transverse edges. This process is very flexible because, to change the length of the plates produced, it is sufficient to modify the frequency of insertion of the slats.

The process which has just been described uses the apparatus according to the invention to make an imprint in the preform intended to be cut to give the plates based on hydraulic binder. Thus, according to the invention and as can be seen from FIG. 10, before introducing the slat 6, an impression 12 is made in the preform 5 opposite the place where it is planned to introduce the batten 6, or an imprint 12bis at the place where it is planned to introduce this batten 6. This makes it possible to compensate for the localized excess thicknesses which may possibly form in the preform 5, due to 'a displacement of material, when the slat 6 has a large dimension. It is also possible to provide for the presence of a straightener 4bis of the conventional type (visible in FIG. 6) downstream of the place where the slat 6 is introduced.

First Variant. According to a variant, the imprint is not used with regard to the introduction of a slat. In such a case, the imprinting device is used alone in the manufacturing line. The impression made in the preform will lead, after the setting of the hydraulic binder, to a form having traditional longitudinal thinned edges, and a depression corresponding to the impression. Depending on whether it is the imprint 12 or 12bis, this depression is located on the face opposite to that carrying the traditional longitudinal thinned edges, or on the same face. According to the first variant, it will be preferable for it to be the imprint 12, therefore on the face opposite to that carrying the traditional longitudinal thinned edges. The advantages will be described later in relation to the finishing process of construction according to the invention.

LINE FOR PRODUCING PLATES BASED ON HYDRAULIC BINDER The apparatus according to the invention can be used, in a line for producing plates based on hydraulic binder from a preform 5 comprising a facing material 1 covered with a composition of hydraulic binder 2 and supported by a conveyor belt 7. So that the device according to the invention can be used optimally on the production line of plates based on hydraulic binder, the distance between the transmission belts of this device is at least equal to the width of the preform

5. Thus, these belts and the pulleys are located on each longitudinal side of the preform. In addition, the apparatus according to the invention is suitably arranged so that, when its transmission belts rotate, its elongated means creates an imprint in the preform 5. The apparatus according to the invention can be above the preform 5, in this case, it creates the imprint 12 or under the preform 5, in which case it creates the imprint 12bis. For practical reasons, it is preferred that the device according to the invention is located above the preform 5. Of course, one could provide two (or more) devices according to the invention, one being located above and the other below the preform, so as to respectively create an imprint 12 on the top of the preform 5 and an imprint 12bis on the underside of the preform 5 (see Figure 10), the underside of the preform 5 being the side of this preform 5 which rests on the conveyor belt 7. The cutting device can be adjusted to cut the preform at the level of an imprint 12. If it is a question of an imprint 12bis produced on the underside of the preform, the cutting device can be adjusted to cut the preform opposite the place where this impression 12bis was made.

Preferably, the production line for plates based on hydraulic binder is a production line for plates with thinned edges. Such a line will now be described in detail with reference to Figures 6 to 15. Next, will be described the mother whose apparatus according to the invention is used in this line. FIG. 11 shows a part of a production line for plates based on hydraulic binder. We can therefore see a slatted magazine 20 formed of a horizontal rectangular surface 21 from the corners of which rise vertically and parallel, four angular pieces 22, in the form of an angle iron and turned towards each other, so as to frame a stack of slats 23. The dimensions of this slat store 20 are such that it can store a high number of slats 23 (see also Figures 12 and 13). The horizontal surface 21 of the slat magazine 20 is supported by feet 24. At the level of the first slat 23, that is to say the one located at the very bottom of the stack, two jacks 26 are arranged in parallel, which are oriented so as to extract the first batten 23 of the stack by pushing it and sliding it towards an inclined plane 27 consisting of a downward inclined surface 28 and a flange 29 at its lower part to retain the batten which has just been extracted and guide her later. At the transverse side 30 of the inclined plane 27, that is to say the side opposite to the conveyor belt 7, a jack 31 is arranged parallel to the longitudinal axis of the inclined plane 27, so that the actuation of this jack 31 can give an impulse to the slat which has just been extracted from the slat magazine 20. The slat thus propelled can then move by sliding parallel to the longitudinal axis of the inclined plane 27, the flange 29 of which guides it towards a second inclined plane 32 which extends the first inclined plane 27, on the transverse side opposite to the side 30. This second inclined plane

32 also consists of an inclined surface 33 provided with a rim 34 at its lower part. It further comprises a stop 35 at its end opposite to the jack 31, this stop being generally made up of a pneumatic shock absorber and being intended to stop the movement of the slat propelled by the jack 31. The flange 34 is provided with openings 36 in front of which are arranged two jacks 37 oriented so as to propel the batten positioned on the second inclined plane 32 upwards of the inclined surface 33. The first inclined plane 27 and the second inclined plane 32 are supported by feet, , respectively 38 and 39. According to a variant visible in FIG. 14, a flat surface 40 is provided parallel to the surface 23, between the latter and the first inclined plane 27 for horizontally supporting a slat extracted from the slat magazine 20 before its descent on the inclined surface 28 of the first inclined plane 27. Thus, as can be seen in FIG. 15, the height of the feet 24, 35 and 36 is chosen such that so that a slat positioned on the second inclined plane 32 is situated at a height less than that of the preform 5. In general: - the longitudinal axis of the flange 34 of the second inclined plane 32 is perpendicular to the longitudinal axis of the mat carrier ; - The means 32, 33, 34, 35 for supporting the displaced batten are located opposite the start of the conveyor belt 7; and the inclined surface 33 of the second inclined plane 32 is adjacent to the conveyor belt 7. The length of the second inclined plane 32 is at least equal to that of the slat 23, that is to say at least equal, and preferably greater , to the width of the preform 5. In this way, as can be understood with reference to FIG. 10, when the jacks 37 are actuated, the slat being on the second inclined plane 32 is pushed up the inclined surface 33, that is to say towards the conveyor belt 7 and the preform 5, and it is wedged between the latter and driven by them. The difference between the length of the slat and the width of the preform 5 makes it possible to grip the slat and remove it once the plaster composition has hardened. The production line according to the invention generally comprises electronic means which control its operation and make it possible, if necessary, to control between them the implementations of different operations. These electronic means provide that after the introduction of a slat in the preform by actuating the jacks 27, the jack 31 is actuated to introduce a new batten on the second inclined plane 32, then the jacks 26 are actuated to introduce another slat on the first inclined plane 27, and so on. The electronic means can vary the frequency of these operations to reduce or increase the length of the plasterboard with thinned edges produced. FIG. 16 represents a part of a production line produced according to a preferred embodiment of the invention. We can see in this figure that the production line includes a variant of the device according to the invention. This device, which can be seen in profile in FIG. 16, comprises four first toothed wheels 201,202,203,204 supported by a frame 205 and surrounded by a chain 206 constituted by links, some of which, the links 207 each support 2 wires, as indicated in relation to FIG. 2. This device is symmetrical with respect to a vertical plane aligned with the direction of movement of the preform 5. Thus, the wires held by the links 207 extend transversely relative to the preform 5 until a second chain, identical to chain 206, and which surrounds second toothed wheels identical to the first toothed wheels 201,202,203,204. The apparatus is provided with an electric motor 209 driving in rotation by means of a belt 211 the shaft 210 on which the wheel 203 and its symmetrical wheel are mounted. The rotation of these wheels causes that of the chain 206 in the direction indicated by the arrow D. This preform 5 is obtained in a known manner by introduction of the hydraulic binder paste according to arrow E between the first facing material 2 and the second facing material 3 and passage of the assembly between the upper trays 214 and lower 215 for forming the apparatus. The distance between the toothed wheels 201,202,203,204 and their symmetrical wheels is at least equal to that of the preform 5 so that these toothed wheels do not touch this preform 5. The apparatus according to the invention is fixed at an appropriate height so that, during the operation of the production line, the movement of the chain 206 causing that of the wires connected to the links 207, these wires pass through the forming plate, it that is to say between the plates 214 and 215 and protrude downward with respect to the upper plate 214. The space occupied by these wires between the upper plate 214 and the second facing material 3 then results in this place by a thinning of the thickness of the preform 5. It goes without saying that the operation of the motor is adjusted so that the chain 206 moves at the same speed as the preform 5 when the wires pass between the plates 214 and 215 The wires then accompany the preform 5 for a few centimeters and, when they separate from it to go up by turning around the wheel 204, they leave an imprint in the upper part of the preform 5. Since it is easy to vary the speed of movement of the chain 206 by acting on the operation of the engine, it is easy to modify the spacing between two cavities and consequently the length of the plates. The frame 205 of the device according to the invention can, as can be seen from FIG. 16, be secured to the plates 214 and 215. It follows that the device according to the invention can be used instead of a forming plate or a master roll that is conventionally used.

Second Variant. This variant corresponds to the case where the batten is introduced no longer before the first forming strip, but between the first and the second forming strip (or possibly between the second and the third forming strip, if applicable). It will be recalled here that the conveyor belt 7 is generally divided into several elements called forming bands. The forming strip 1 is the one at the top. A conventional conveyor belt generally comprises 2 or 3 or even 4 forming bands. These, as indicated above, include "tapes" so as to form the longitudinal tapered edges. The other elements remain identical (imprints 12 or 12bis, as the case may be), except that the batten is introduced at a point on the line at which the hydration of the hydraulic binder has started (see below in the section on the third variant). The other constituent elements are offset by the same amount (for example the straightener 4bis is offset at or after the first roller driving the second forming strip; in this case the straightener takes the form of a roller having a substantially identical peripheral speed to that of the conveyor belt 7). By injecting the batten (6,23) at this level, one can have a consistency of the ideal preform at the time of this secondary forming. Synchronization means can also be used as described below in the section on the third variant.

Third Variant. This variant is shown in Figure 17. In it, the impression 12 produced, in particular by the device according to the invention, is "pushed back" upwards by a device 300 located under the preform. This system is in fact opposite to that which is the subject of American patent n ° 2 991 824. Furthermore, compared to this patent, the system used to repel the impression is located downstream of the forming device. Advantageously, this reversing device is located between the bands 1 and 2 (but it is also possible to place it between the bands 2 and 3, if necessary). This device is placed at a point on the line at which the hydration of the hydraulic binder has started. Preferably, this device is located at a location corresponding to 5% to 30% of the hydration, and / or at a location located between 40 and 110m from the length of the conveyor belt 7 (for example for a line with a speed about 70 m min). This device 300 is placed between the bands 1 and 2, referenced 301 and 302, respectively. These bands are driven by rollers 303 and 304, respectively. The device 300 comprises on the one hand a secondary forming device 300a. This comprises, on a chassis (not shown), a band 305, rotating at a linear speed equal to the speed of the bands 301 and 302. This prevents slippage of the facing. On this strip 305 is fixed one or more forming slat (s) 306 coupled to this strip 305. In the following description is given with reference to a single slat but depending on the dimensions of the devices, the desired plates , etc, several slats can be used. This strip is mounted on rollers 307 and 308, at least one of which is preferably motorized. A flat sliding plate 309, for example made of marble, is disposed between the preform and the strip 305 so that the latter are in contact on a flat surface. Opposite this part is a "counter-device 300c. This comprises, on a chassis (not shown), a band 310, rotating at a linear speed equal to the speed of the bands 301 and 302, this band 310 being mounted on rollers 311 and 312, at least one of which is preferably motorized. A flat, sliding plate 313, for example made of marble, is placed opposite between the preform and the band 310 in a similar manner to the arrangement of the plate 309 and the strip 305. In operation, the forming strip 306 comes opposite the upper cavity 12 in the preform. In doing so, when the strip 306 passes at the same time as the preform between the two plates 309 and 313, the impression is "chased" on the other side of the preform. A preform arrives on the forming strip 302 which has a recess corresponding to a transverse thinned edge (on the same side of the plate as the longitudinal thinned edges). Thus, the preform passes between the two bands 305 and 310 which are preferably motorized at the speed of movement of the preform. The preform is therefore in contact only with moving elements, so that the relative movement preform / bands is zero. There is therefore no friction. The dimensions of the device (in its length) are of the order of a few meters (typically there is contact for 5 to 10m), in general sufficient to ensure secondary forming. Means for adjusting, not shown, the pressure exerted by this "counter device" may be present. They may in particular be jacks or counterweights capable of exerting an adjustable pressure on the assembly. Synchronization means ( not shown) are preferably supplied so that the secondary forming slat 306 is substantially opposite the cavity 12. It is possible to use a cutting system composed of a wheel placed on top of the preform and driven in rotation by the displacement of the latter. The wheel is graduated and coupled to a counter which actuates the desired devices. It is also possible to use a system comprising a step of marking the facing of the preform (for example a point), and the detection of this mark and actuation of the devices accordingly. Among these devices actuated by the detection of the mark, mention may be made of those for making the imprint 12 or 12bis, the introduction of e the batten (6,23) or the triggering of the rotation of the strip 305 carrying the batten 306, the cutting of the preform at the end of the forming step, etc. Another embodiment is shown in Figure 18 (the same references as in Figure 17 are not repeated). In this embodiment, the device 300 further comprises a calibration device 300c. The slat 306 is retracted when the strip 305 rotates around the roller 308; the preform then enters the calibration device 300C. This comprises, on a chassis (not shown), a band 314, rotating at a linear speed equal to the speed of the bands 301 and 302, this band 314 being mounted on rollers 315 and 316, at least one of which is preferably motorized. A flat sliding plate 317, for example made of marble, is disposed between the preform and the band 314 in a similar manner to the arrangement of the plate 309 and the band 305. A straightener of the same type as that described for the second variant can possibly be expected.

Fourth Variant. This variant corresponds to the case where the device of FIGS. 17 or 18 is reversed, namely that the forming strip 306 is arranged not to repel the impression and form the transverse thinned edges on the same side as the longitudinal thinned edges, but on the contrary to "confirm" the impression and the shape reservation. According to this embodiment, the application of the forming batten at a stage at which the hydraulic binder has started its hydration makes it possible, as above, to have a consistency of the ideal preform at the time of secondary forming. As in the case of the third variant, a plate is obtained with four thinned edges, the longitudinal and transverse edges being on one side and the other of the plate. The advantages will be described later in relation to the finishing process of construction according to the invention.

Fifth and Sixth Variation. These variants correspond to the cases where the imprint 12 is replaced in the second and third variants above by the imprint 12bis. We obtain effects which are therefore opposite.

In the above variants, the length of the slat 306 is approximately equal to the width of the preform. Furthermore, the batten used in the invention, and in particular batten 306, can have a parallelepiped profile, but also in the form of a triangle, generally isosceles, the base of which is parallel to the mat 7.

We could also have third and sixth modified variants. For the record, the third and sixth variants have in common that the imprint 12, respectively 12bis, is "repelled" by a device under the preform, respectively above the preform. In the third and sixth variants, the imprint is "pushed back" in its entirety, that is to say that the facing paper is substantially flat once the imprint has been "pushed back". It is possible to foresee that the action of pushing back the impression is only partial, namely that there remains a depression on each face of the plate, one being more pronounced than the other. For example, it is possible to adjust the device 300 so that the ratio of the depths of the depressions on each face is between 1 and 10, preferably between 2 and 5. For example, for a standard plate BA13, of thickness 12, 5mm, the depth of the depression on the "pushed back" side can be 4mm while the depression on the original side can be 1.5mm.

Second construction method; plate used in this. According to another aspect, the invention relates to a process for building a finishing work, using the plates with four thinned edges, two of which are thinned on one side while the other two are on the other face of the plate. Such plates can be obtained by the first variant (with the imprint 12) fourth and fifth variants, as well as the third and sixth modified variants. Such a plate is represented diagrammatically in FIG. 19. It can be seen there that the thinnings are arranged on each face of the plate, in an opposite manner (the thinnings on the edge are on the cream facing side (10) while the thinnings at the end are on the 'other side, gray side (25bis)). The dimensions of the thins 25bis are generally of the same order of magnitude as those of the thins 25 (which corresponds to the dimensions of the batten in the case of the fourth or fifth variant or of the elongated means 110 comprising the wires 111 in the case of the first variant for example). The thinned 25bis can therefore have a depth of between 0.5 and 4 mm, preferably between 1.5 and 4 mm. The width can be comprised of the thinned between 2 and 15cm, preferably between 5 and 10cm. The longitudinal thinnings have the standard dimensions in the art, as given by the "tapes" in a conventional manner. The construction process for the finishing work (the partition can be vertical, inclined or horizontal - false ceiling) according to the invention comprises the following steps (and which will be described in more detail below): a) the plates are arranged according to the invention (for example as shown in Figure 19) on a frame, the plates being butted at the thinned edges; b) the plates are fixed to the frame at the thinned edges; c) the plates are assembled together with at least one sealing coating; and optionally d) the joints are finished with an additional finishing coating. During step b), the transverse thinned edges, which are on the side of the plate not visible to the installer, are "turned over" or "reassembled" under the effect of fixing by screws, nails or the like, because this plate area is tightened on the frame. In doing so, they then release a thinned edge on the same side of the plate as the longitudinal thinned edges (or thinned edges). Thin edges are then obtained at each level of joining of the plates.

According to one embodiment, the transverse thinned edges (25a), namely those which are on the side of the gray facing are identified by a specific marking on the side of the cream facing so that the user (the plasterer who mounts the partition) knows that it has thinned edges on the gray facing side. When pairing the plates, the user will therefore know that he is in the presence of such thinnings, and therefore he will be able to treat the joints accordingly. The marking of these ammcis can take any suitable form, such as a repeated pattern. The presence of this marking offers an advantage when two plates according to the invention are abutted at the level of the transverse thinnings; in fact when the transverse thinned edge is terminated, for example on a wall, the marking on the cream facing of the presence of this thinned on the gray facing has no appreciable influence on the mounting or the way of treating the junction. This marking is identified in particular in FIG. 20 by the signs 26a, 26b, 26c and

26d at the thinned edges (25bis). This marking is present on the cream side and identifies the transverse thinned edge intended to be matched with a transverse edge of the same nature of a second plate according to the invention. This marking also makes it possible to identify the width of the transverse thinning (25a) and to adapt the joint treatment accordingly, in particular by using a tool or spatula of appropriate size. For example, the plasterer can simply lay the plaster, in particular finishing, at the only level of the marks and be guided by them. In addition, the marking may include repeated marks. Insofar as the valley formed by the thinned edges (25a) is obtained by "turning" during step (b), it is preferable to use a sufficient number of screws to ensure this turning over easily. For example one can use 3, preferably 5 screws as is conventional to do, but one will prefer from 6 to 10, advantageously 7 repeated marks. The number of marks will then correspond to the number of screws to be used. The plates with the marking are made as above, with the difference that the facing paper is printed before receiving the paste. You can print in situ or use a reel of paper already printed. The production line then includes appropriate printing means.

The subject of the invention is also a new plate based on hydraulic binder with four thinned edges and a process for construction of the finishing work using this plate. This plate does not have the drawbacks during their assembly, which are generally associated with plates with conventional 4 thinned edges, as indicated below. Plasterboard is known. In general, such plates include two longitudinal tapered edges. When the plates abut at the transverse edges, there is necessarily an additional thickness at the joint.

A first technique consists in shifting the rail of the framework by approximately 2mm in order to create the equivalent of a thinned. However, this technique is difficult to implement given the differences that necessarily occur. Another technique which has been proposed consists in using plates with four thinned edges. Many documents describe their preparation. These plates have in common the presentation of four tapered edges, longitudinal and transverse, so that joints using a plaster can be formed on the four sides. To date, all the plates have thinned edges that are substantially similar in terms of dimensions, the width and depth of the thinnings being substantially identical for the four edges. Although the use of four thinned edges has certain advantages, there are still disadvantages. Indeed, the thinned edge has a width generally between 40 and 80mm, typically 60mm; both current standards and practice impose these values. However, the tool used to apply the tape bonding coating (when one is used) and the plugging coating has a width generally greater than 120 mm, which necessarily causes extra thickness at the intersection of the joints during the application of the coating on the transverse joints, thus reducing the attractiveness of the plates with four thinned edges, already penalized by their higher cost. US-P-4397123 describes a plate according to two embodiments. According to the first embodiment, the plate ends comprise a removable part, which after removal of the latter gives an edge in the form of a slot. This niche, once in place, is "turned over" to form a valley intended to receive the coating. This solution is technically very complicated; no industrial manufacturing process has been described. According to a second embodiment, the plate described has a thinned out on the gray side of the plate, with a width of this thinned out of 12 inches, ie more than 30 cm. There is again no description of any method for obtaining this second embodiment.

FIG. 19 represents a plate according to a first embodiment. The plate traditionally comprises a hydraulic binder, generally plaster, between two facings. The facing materials may consist of sheets of paper or cardboard, venetian mats or any material known to those skilled in the art as being able to serve as facing material. The plate comprises on one face two first parallel thinned edges (10) and on the other face two other, second, parallel thinned edges (25a) perpendicular to the first. The thinnings are placed on each side of the plate, in an opposite manner (the thinnings on the edge are on the cream facing side (10) while the end thins are on the other side, on the "gray" side (25a)). The depth of the thinned is generally between 0.5 and 4mm, preferably between 0.5 and 3mm, more preferably between 0.6 and 2.5mm, or even between 0.6 and 1.8mm, advantageously between 0 , 8 and 1.8mm or 0.5 and 1.5mm. The width of the second thinnings (25bis) is here specific in the embodiment of the invention, and in general between 100 and 200mm, preferably between 120 and 180mm or between 150 and 200mm or between 100 and 150mm. The first longitudinal thinnings have a depth of substantially the same size, while their width is substantially smaller, for example between 40 and 80mm. In particular, the ratio of the widths between second transverse thinnings and first longitudinal thinnings is generally between 1.5 and 5, preferably between 2 and 4. In a variant, the ratio can also be reversed, the longitudinal edges then having a width greater than that of the transverse edges. In yet another variant, the four edges have large widths. FIG. 21 represents a plate according to a second embodiment, seen from above. In this case, the plate includes the four thinned edges on the same face of the plate. The dimensions given with reference to the embodiment of FIG. 1 and the other variants also exposed in relation to this FIG. 19 apply mutatis mutandis here. FIG. 22 represents a sectional view of a specific thinned edge according to the invention. In this embodiment, the thinnedness is present on both sides of the plate at the same time. In this case, the plate also comprises two third thinned edges (25ter) parallel to the second thinned edges (25bis), on the other face of the plate. The dimensions are given again here, namely: X thickness of the plate conventionally between 6 and 25mm; Y width of thinned T between 100 and 200mm, preferably between 120 and 180mm or between 150 and 200mm as above; Z '(for example depth of the second thinnings 25bis) and Z "(for example depth of the third thinnings 25ter) such that Z' + Z" is between 0.5 and 4mm, preferably between 0.5 and 3mm, more preferably between 0.6 and 2.5mm, or even between 0.6 and 1.8mm, advantageously between 0.8 and 1.8mm or 0.5 and 1.5mm. The ratio of the values Z 'and Z "or Z': Z" is for example between 1 and 10, preferably between 2 and 5. The presence of these thinnings on each side offers an additional advantage. When the thinned edges (25bis) are present on the side opposite the thinned edges (10), during installation, they are "turned over", as indicated above. It then forms a bend with a relatively large radius of curvature. The presence of the thinned edges (25ter) makes it possible to better delimit the final valley formed by the inversion of the thinned edges (25bis). We obtain a true valley of the same type as that formed by traditional thinnings (namely substantially shaped according to an isosceles triangle). This allows optimal treatment of the joint without excessive consumption of plaster and with perfect flatness.

The plates with four thinned edges can be prepared by various methods. In the case of the plate with four thinned edges on the same face, the methods are known. One can for example use the methods described for example in US-P-2991824 or US-P-2246987 or the requests in the name of the applicant for example PCT / FR03 / 01373; PCT / FR03 / 02281, PCT FR03 / 00118, PCT FR03 / 12880, PCT / FR03 / 00606. In the case of the plate with the second thinned edges (transverse) on the face opposite to that carrying the first thinnings (longitudinal), one can use: - the method described above with reference to the previous figures. - A variant of the method according to US-P-4781558, in which the drum is modified so as to carry at least one rib or bump along the axis of the drum. - A process using the forming strip according to US-P-2991824 associated with upper rollers forming the longitudinal thinnings according to US-P-1676318 or US-P-2246987. - A process in which a plate is pressed, for example in the wet state, in a suitable mold. - a process in which the transverse thinned edge is obtained by rescanning in the thickness and gluing. The construction process for the finishing work (the partition can be vertical, inclined or horizontal - false ceiling) according to the invention comprises the following steps: a) the plates according to the invention are placed (for example as shown in the figure 19 or 21) on a frame, the plates being abutted at the thinned edges; b) the plates are fixed to the frame at the ammcis edges; c) the plates are assembled together with at least one sealing coating; and optionally d) the joints are finished with an additional finishing coating. As a preliminary, it should be noted that the present process can use a tape bonding coating or not; it is in fact possible to use a strip, for example a strip of paper, made of venetian fiber fabric, self-adhesive or not. The tape bonding coating, when used, may be the same or different from the plugging coating. Likewise, this sealing coating can be identical to or different from the additional finishing coating, when such a complementary finishing coating is used. In the case of the plate with transverse thinned edges on the side opposite to that carrying the longitudinal thinned edges, during step b), the transverse thinned edges, which are on the side of the plate not visible to the installer, are "turned" or "reassembled" under the effect of fixing by screws, nails or other, because this area of the plate is tightened on the frame. In doing so, they then release a thinned edge on the same side of the plate as the longitudinal thinned edges (or thinned edges). Thin edges are then obtained at each level of joining of the plates. This is illustrated in FIGS. 23A and 23B, in which the armature (430) receives the transverse thinned edges (25bis), which are "turned over" or "reassembled" under the effect of fixing by screws, nails or the like (identified by the reference (431) in the figures). In the case of the plate with transverse thinned edges on the same side as that carrying the longitudinal thinned edges, step b) is the conventional step during installation. The invention offers a particular advantage over the plates known from the prior art with four thinned edges. This advantage will be more apparent from the figures which follow. FIGS. 24A, 24B and 24C represent the installation diagram with plates with four conventional thinned edges. FIG. 24A represents the abutted plates. FIG. 24B represents the plates of which a joint (after laying the strip in the two joints) is treated with a layer of sealing plaster. The hatched area represents the area of application of the coating. Conventionally; there is an extra thickness on the sides of this application area (at the level of the plates bordering the thinned). FIG. 24C represents the plates, the second of which a joint is treated with a layer of sealing plaster. The hatched area again represents the area of application of the coating. Conventionally; there is an additional thickness on the sides of this application area (at the level of the plates bordering the raminci). On the other hand, there is also a significant excess thickness at the joint crossing, this joint crossing being identified by the reference (411) in the figures. In fact, the first additional thickness obtained in the step shown in FIG. 24B is added to the additional thickness obtained in the step shown in FIG. 24C. Figures 25A, 25B and 25C show the installation diagram with plates with four thinned edges according to the invention. FIG. 25A represents the abutted plates, with the edges turned over if necessary. Once installed, the plates according to the invention offer thinnings on the visible face, as has been explained above. FIG. 25B represents the plates of which a joint (after laying the strip in the two joints) is treated with a layer of sealing plaster. The hatched area represents the area of application of the coating. Conventionally; there is also an extra thickness on the sides of this application area (at the level of the plates bordering the thinned). FIG. 25 C represents the plates, the second of which a joint is treated with a layer of sealing plaster. The hatched area again represents the area of application of the coating. This time, the tool being of smaller dimensions compared to the size of the thinned edges, the coating is located in the valley formed by the large thinned edges. Thus, at the joint crossing, there is no longer any additional thickness which is added to the first additional thickness obtained in the step shown in FIG. 25B. This gives a crossing of joints without extra thickness, and therefore a perfectly flat surface. A tool is preferably used whose width is greater than twice the width of said first parallel thinned edges (10) and less than or equal to twice the width of said other parallel thinned edges (25a). The invention offers yet another advantage. When laying on suspended metal frames, there is often a connection of two plates at the level of a rail. When this rail is offset, for example as a result of a deficient assembly, with conventional plates this offset is visible. Thanks to the plates according to the invention, as the thinned is relatively large, this offset is no longer visible to the eye. The invention offers yet another advantage. Insofar as the first, second, or the two thinned edges are larger, it is possible to use larger amounts of coating (for a greater thickness), in particular of capping. Thus, during a possible sanding, there is less risk of seeing the band appear (by the presence of lint or by its visible spectrum through the coating). As above, a marking can be used. It is also possible to insert the marking for a plate in which the thinned edge of wide width is on the same side as the other thinned edges, in particular when the depth is small and makes the identification of said thinned edge difficult.

The plates can be installed either with crossed joints or with aligned joints.

Claims

1. Plate in hydraulic binder with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and on the other face two second other parallel thinned edges (25bis) perpendicular to the first.

2. Plate according to claim 1, wherein said second parallel thinned edges (25bis) are transverse.

3. Plate according to claim 1 or 2, further comprising two third thinned edges (25ter) parallel to the second thinned edges (25bis), on the other face of the plate as the face comprising said second thinned edges (25bis).

4. Plate according to claim 3, in which the ratio of the depth of said second thinned edges (25bis) to the depth of said third thinned edges is between 1 and 10, preferably between 2 and 5.

5. Plate according to one of claims 1 to 4, wherein said second other parallel thinned edges (25bis) have a width between 100 and 200mm.

6. Plate according to claim 5 wherein the width of said second parallel ammcis edges (25bis) is between 120 and 180mm or between 150 and 200mm or between 100 and 150mm.

7. Plate according to one of claims 1 to 6 wherein said first (10) and second parallel thinned edges (25bis) have a substantially equal width.

8. Plate according to one of claims 1 to 7 wherein said other parallel thinned edges (25bis) have a width such that the width ratio of said second parallel thinned edges (25bis) to the width of said first parallel thinned edges (10) is included between 1.5 and 5, preferably 2 and 4.

9. Plate in hydraulic binder with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and either on the same face or on the other face, two second parallel thinned edges (25bis) peφendicular to the first, said other parallel thinned edges (25bis) having a width of between 100 and 200mm.

10. Plate according to claim 9 wherein the width of said second parallel thinned edges (25bis) is between 120 and 180mm or between 150 and 200mm or between 100 and 150mm.

11. Plate according to claim 9 or 10 wherein said first (10) and second parallel thinned edges (25bis) have a substantially equal width.

12. Plate according to claim 9 or 10 in which said other parallel thinned edges (25bis) have a width such that the width ratio of said second parallel thinned edges (25bis) over the width of said first parallel thinned edges (10) is between 1, 5 and 5, preferably 2 and 4.

13. Plate in hydraulic binder with a facing on each of its faces, comprising on one face two first parallel thinned edges (10) and either on the same face or on the other face two second parallel thinned edges (25bis) peφendicular to the first , said second parallel tapered edges (25bis) having a width such that the width ratio of said second parallel tapered edges (25bis) to the width of said first parallel tapered edges (10) is between 1.5 and 5.

14. Plate according to claim 13, in which the ratio is between 2 and 4.

15. Plate according to claim 13 or 14, wherein the width of said second parallel thinned edges (25bis) is between 100 and 200mm, preferably between 120 and 180mm or between 150 and 200mm.

16. Plate according to one of claims 9 to 15, wherein said second parallel thinned edges (25bis) are transverse.

17. Plate according to one of claims 9 to 16, further comprising two third thinned edges (25ter) parallel to the second thinned edges (25bis), on the other face of the plate as the face comprising said second thinned edges (25bis).

18. Plate according to claim 17, in which the ratio of the depth of said second thinned edges (25bis) to the depth of said third thinned edges is between 1 and 10, preferably between 2 and 5.

19. Plate according to one of claims 9 to 18, in which said second parallel thinned edges (25bis) are on the same face as said first parallel thinned edges (10).

20. Plate according to one of claims 9 to 18, wherein said second parallel thinned edges (25bis) are on the other side than the face of said first parallel thinned edges (10).

21. Plate according to one of claims 1 to 8 or 20, this plate comprising a marking (26a, 26b, 26c, 26d) on the face comprising the first two parallel thinned edges (10) and identifying the presence of the other two edges parallel thinnings (25bis) peφendicular to the first, said plate being intended to be used in cooperation with a second identical plate, a parallel thinned edge (25bis) of a first plate being joined to a parallel thinned edge (25bis) of a second plate, these thinned edges (25bis) of said plates being identified by the marking (26a, 26b, 26c, 26d) present on the face comprising the first two parallel thinned edges (10) of said plates.

22. Plate according to claim 21, in which the marking comprises more than 3, in particular more than 5 repeated marks, preferably from 6 to 10, advantageously 7 repeated marks.

23. Plate according to one of the preceding claims, in which the hydraulic binder is plaster.

24. Method of construction of the second work comprising the following steps: a) the plates according to one of claims 1 to 23 are placed on a frame, the plates being abutted at the thinned edges; b) the plates are fixed to the frame at the thinned edges; c) the plates are assembled together with at least one sealing coating; and optionally d) the joints are finished with an additional finishing coating.

25. The method of claim 24, wherein the sealing coating is applied at the joints between plates with a tool whose characteristic dimension is greater than twice the width of said first parallel thinned edges (10) and less than or equal to double the width of said other parallel thinned edges (25bis).

26. Method of construction of the second work comprising the following steps: a) the plates according to one of claims 21 or 22 are placed on a frame, the plates being abutted at the thinned edges, a parallel thinned edge (25bis) d 'a first plate being abutted to a parallel thinned edge (25bis) of a second plate, these thinned edges (25bis) of said plates being identified by the marking (26a, 26b, 26c, 26d) present on the face comprising the first two parallel thinned edges (10) of said plates; b) the plates are fixed to the frame at the thinned edges; c) the plates are assembled together with at least one sealing coating; and optionally d) the joints are finished with an additional finishing coating.

27. The construction method as claimed in claim 26, in which the sealing plaster and / or the finishing plaster is placed within the limit defined by the marking (26a, 26b, 26c, 26d) of the plate.

28. Construction method according to one of claims 24 to 27, wherein, during step c), using a strip, in particular a paper strip, of glass fiber fabric, self-adhesive or not.

29. A method of manufacturing a plate according to one of claims 1 to 8 or 20, comprising the following steps: 1) is poured on a facing material (1) supported by a conveyor belt (7) comprising at least two forming strips (301,302) provided with longitudinal tapes, a composition of hydraulic binder (2) and covered with a second facing material so as to obtain a preform (5), then an impression (12) is made in the upper part of the preform before the first forming strip; 2) the hydraulic setting of the hydraulic binder composition (2) is allowed to take place; and 3) the preform (5) is cut at the level of the thinning (8) created by the impression (12) in a plate by hydraulic binder with a facing on each of its faces, comprising on one face two first thinned edges parallel and on the other side two other thinned edges parallel peφendicular to the first.

30. A method of manufacturing a plate according to claim 21 or 22, comprising the following steps: 1) is poured onto a facing material (1) supported by a conveyor belt (7) comprising at least two forming strips (301,302 ) provided with longitudinal tapes, a hydraulic binder composition (2) and covered with a second facing material so as to obtain a preform (5), then an impression (12) is made in the upper part of the preform before the first forming tape; 2) the hydraulic setting of the hydraulic binder composition (2) is allowed to take place; and 3) the preform (5) is cut at the level of the thinning (8) created by the impression (12) in a plate by hydraulic binder with a facing on each of its faces, comprising on one face two first thinned edges parallel and on the other side two other thinned edges parallel peφendicular to the first; in which an impression is made of the facing material (1) with the marking (26a, 26b, 26c, 26d).

31. The manufacturing method according to claim 29 or 30, characterized in that the hydraulic binder comprises plaster.

32. Line for the production of plates based on hydraulic binder from a preform (5) comprising a facing material (1) covered with a composition of hydraulic binder (2) and supported by a conveyor belt (7), comprising at least two forming strips (301,302) provided with longitudinal tapes; this line further comprising a device making an impression (12) of the preform before the first forming strip, this impression being produced on the upper part of the preform.

33. Production line according to claim 32, in which the device for forming the imprint (12, 12bis) in a preform (5) based on hydraulic binder comprises at least: - a frame (101); -two first pulleys (102,103) supported at a first end (104) of the frame (101) and two second pulleys (105,106) at a second end (107) of the frame (101); the first pulleys (102,103) and second pulleys (105,106) being in parallel planes; the pulleys facing one (102,103) of the other (105,106) being identical; -two transmission boards (108,109) respectively surrounding the first pulleys (102,103) and the second pulleys (105,106); at least one wire (111) removably attached to the belts (108,109) and extending between these belts (108,109), so that its longitudinal axis is parallel to the rotation rate of the pulleys (102,103,105,106); the distance between the transmission boards (108,109,206) of this device being at least equal to the width of the preform (5) and this device being arranged in an appropriate manner so that when its transmission boards (108,109,206) rotate, its or its wire (s) (111) creates (s) an imprint (12 or 12bis) in the preform (5).

34. Production line according to claim 32 or 33, characterized in that the hydraulic binder comprises plaster.

35. A method of manufacturing a plate based on hydraulic binder from a preform (5) intended to be cut, comprising the following steps: 1) poured onto a facing material (1) supported by a conveyor belt (7) comprising at least two forming strips (301,302) provided with longitudinal tapes, a composition of hydraulic binder (2) and is covered with a second facing material so as to obtain a preform (5), then an impression is made (12,12bis) in this preform before the first forming strip; 2) the hydraulic setting of the hydraulic binder composition (2) is allowed to take place in part on at least one forming strip; 3) a slat (6,23) or (306) is introduced under the partial setting preform, opposite the place or the place where the impression (12,12bis) was made; 4) the preform (5) is cut at the level of the thinning (8) created by the slat (6,23) or (306).

36. The method of claim 35, wherein the setting according to step 2) corresponds to a hydration of between 5 and 30%.

37. The method of claim 35 or 36, wherein the batten (6,23) or (306) is introduced after the first forming strip (301).

38. Method according to one of claims 35 to 37, in which the impression (12) is made in the upper part of the preform and the slat (306) is introduced opposite the place where the impression ( 12) has been produced so as to form transverse thinned edges on the same side as the longitudinal thinned edges formed by the longitudinal tapes.

39. Method according to one of claims 35 to 38, wherein the batten (6,23) is removed after the complete hydraulic setting.

40. Method according to one of claims 35 to 39, wherein the batten (306) is removed before the complete hydraulic setting.

41. The method of claim 40, wherein the slat (306) is introduced for a time corresponding to 0.5 to 5% of the hydration.

42. The manufacturing method according to one of claims 35 to 41, characterized in that the hydraulic binder comprises plaster.

43. Line for producing sheets based on hydraulic binder from a preform (5) comprising a facing material (1) covered with a composition of hydraulic binder (2) and supported by a conveyor belt (7), comprising at least two forming strips (301,302) provided with longitudinal tapes; this line further comprising a device making an impression (12,12bis) of the preform before the first forming strip, and a device for introducing under the preform between two strips forming a batten (6,23) or ( 306), opposite the place or the place where the impression (12,12bis) was made.

44. A production line according to claim 43, in which the device for forming the imprint (12, 12bis) in a preform (5) based on hydraulic binder comprises at least: - a frame (101); -two first pulleys (102,103) supported at a first end (104) of the frame (101) and two second pulleys (105,106) at a second end (107) of the frame (101); the first pulleys (102,103) and second pulleys (105,106) being in parallel planes; the pulleys facing one (102,103) of the other (105,106) being identical; -two transmission boards (108,109) respectively surrounding the first pulleys (102,103) and the second pulleys (105,106); at least one wire (111) removably attached to the boards (108,109) and extending between these boards (108,109), so that its longitudinal axis is parallel to the axis of rotation of the pulleys (102,103,105,106); the distance between the transmission boards (108,109,206) of this device being at least equal to the width of the preform (5) and this device being arranged in an appropriate manner so that when its transmission boards (108,109,206) rotate, its or its wire (s) (111) creates (s) an imprint (12 or 12bis) in the preform (5).

45. Production line according to claim 43 or 44, wherein the device for introducing under the preform between two strips for forming a slat (6,23), opposite the place or the place where the impression (12,12bis) has been made comprises at least: - a slat store (20), - at least one slat (6,23); means (26) for extracting one slat (6,23), at a time, from the slat store (20); -means (27,28,29) for receiving the extracted slat (6,23); means (31) for moving the extracted slat (6,23) in a direction parallel to its length; means (32, 33, 34, 35) for supporting the displaced batten (6,23); and -means (37) for sliding the slat (6,23) under the facing material (1).

46. Production line according to one of claims 43 to 45, wherein the device for introducing under the preform between two forming bands of a batten (306), opposite the place or the place where the impression (12,12bis) was made comprises at least: - a device (300a) for secondary forming, said device comprising: a strip (305) supporting a forming strip (306), this strip being mounted on rollers (307,308), this strip sliding on a plate (309), preferably made of marble, and facing the other side of the preform: a counter device (300b) said counter device comprising: a strip (310) mounted on rollers (311,312), this strip sliding on a plate (313), preferably made of marble; the strips (305,310) having a linear speed substantially equal to that of the forming strips (301,302).

47. The production line according to claim 46, further comprising, downstream of the secondary forming device (300a) and also facing the counter-device: a calibration device (300c) said device comprising: a strip (314) mounted on rollers (315,316), this strip sliding on a plate (317), preferably made of marble; the strip (314) having a linear speed substantially equal to that of the forming strips (301,302).

48. Production line according to one of claims 43 to 47, characterized in that the hydraulic binder comprises plaster.