IE47825B1 - Process and apparatus for the manufacture of a band or boards of plaster - Google Patents

Abstract

La présente invention se rapporte à la coulée d'un produit évolutif fluide, tel qu'un mélange de plâtre et d'eau. L'invention propose un procédé de fabrication de plaques par coulée, sur une sole mobile d'un mélange de plâtre et d'eau, contenu dans une réserve en charge par rapport à la sole de coulée, au travers d'une fente transversale, parallèle et adjacente à la sole de coulée, dans lequel on introduit en continu du produit de renouvellement dans la réserve par une pluralité de jets immergés dans la masse du produit de la réserve. L'invention propose également un dispositif pour mettre en oeuvre ce procédé et des produits fabriqués par ce procédé. L'invention est applicable à la fabrication de plaques de plâtre.

Description

This invention relates to the manufacture of a band or boards of plaster.

The invention provides a process for the manufacture of a band or boards of plaster by casting on a movable casting bed travelling at uniform velocity a mixture essentially of plaster and water contained in a reservoir placed directly over the casting bed at a pressure head with respect to said casting bed, said mixture being cast through a transverse slot which is parallel and adjacent to the casting bed and formed under the downstream wall of said reservoir, in which replacement mixture is continuously introduced in liquid form into the reservoir by a plurality of jets immersed in the mass of mixture already in the reservoir, which jets are spaced apart in such a manner and have such force that they produce in the mixture of the reservoir an agitation the flow lines of which are visible over the whole surface of the reservoir.

The invention also provides apparatus for the ; manufacture; of a band or boards of plaster by casting a mixture essentially containing water and plaster, comprising a bottomless trough resting on a movable casting bed and having :an opening bounded by said casting bed and by the lower edge of the plate which forms the downstream wall of the - 2 47825 trough, in which said downstream plate is equipped with a plurality of feed tubes for mixture, which tubes are distributed over the whole length of said downstream plate on the outside of the trough and pass through the downstream plate to open into the interior of said trough and are connected to devices which supply energy to the mixture of plaster and water.

The invention also provides construction elements containing plaster, in which the plaster is employed according to the process of the invention.

The invention will now be described more particularly, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic drawing of a complete plaster board manufacturing line; Figure 2 is a sketch representation of plaster pouring apparatus; Figure 3 is a view of a receiving container in which the mixture runs when coming out of the mixer; Ficrure 4 is a multiple outlet distributor which distributes the mixture to several manufacturing lines or to various places on one line: Figure 5 is a pouring head; Figure 6 shows the detail of a pouring head front plate.

Figure 7 shows the detail of a pouring head back plate; Figure 8 shows various reinforcement placing modes; Figure 9 illustrates a multiple pouring head; Figure 10 is a side elevation partially broken away of a plaster board of the invention; Figure 11 is a side, elevation partially broken away of a plaster board of the invention having three layers of different densities; qo Figure 12 is a side, elevation partially broken away of a plaster board of the invention having three layers of different densities and reinforcement between adjacent layers; Figure 13 is a side elevation partially broken away of a plaster board in accordance with the invention having a q5 reinforcement embedded therein; Figure 14 is a side elevation partially broken away of a plaster board in accordance with the invention having a panel of glass wool fibers secured to one face of a plaster board; Figure 15 is a side view partially broken away of a three layer reinforced plaster board in accordance with the invention; Figure 16 is a view of ah alternative embodiment of the receiving container of Figure 3; Figure 17 shows another reinforcement placing mode; Figure 18 is a side elevation partly broken away of a plaster board reinforced by a continuous filament mat encased between two layers of glass fiber netting; Figure 19 shows a plaster board with a reinforced layer of chopped glass fibers; and Figure 20 is a view in side elevation of plaster hoard attached to a glass wool insulating pad.

Detailed Description of the Invention Figure 1 shows a manufacturing facility for making plaster board building components reinforced for instance with fiber glass. This facility includes plaster and water mixture production means, and means which are objectives of the present application, making it possible to pour the mixture in a continuous process upon a moving conveyor and to eventually reinforce it.

Plaster powder contained in a hopper 1 is distributed on a weight-sensitive conveyor belt 2 set beforehand for a determined flow rate P of plaster powder and then brought to a vibrating pouring spout 3 through which it falls into a mixer M. A water feed regulator 4 having a valve 4A and a flow meter 4B introduces water in mixer M at flow rate W. Mixer M is a mixer with a turbine 5, cylindrical, vertical container 6, with a tapering lower section wall 6A. An intermediate trough bottom 7A is constituted by the top surface of a solid of revolution core 7, tapering downwardly and placed inside also tapering casing constituted by the container 6 lower section wall 6A. This core 7 is centered on the container 6 axis and its dimensions are such that a ringshaped space remains around it between it and wall 6A to allow mixture runoff. In a certain type of construction, trough 6 lower section is conical and core 7 is a cone placed inside it, tip downward, its flat base forming the intermediate bottom. The mixture coming out of the mixer M is received ih an ejection device 8 comprising a conical casing 9 placed with its tip upward and with a plane base 10. A collector pipe 11 comes out of ejector device 8 flush with base 10 tangentially to receiving container 9 and extends in the direction of rotation of mixer turbine 5. The mixture outcoming flow rate is regulated by a valve 12 mounted on collector pipe 11. This valve comprises a rigid cylindrical housing 13, an inner elastic sleeve 14 and a fluid intake pipe 15 in communication with the space between rigid housing 13 and sleeve 14. This fluid intake pipe 15 is connected to a fluid (generally air) supply; the fluid pressure is adjusted in order to bring about a desired compression of elastic sleeve 14 resulting in a certain closing setting of valve 12.

In order to prevent any plaster deposit in the narrow 8 2 5 channel created by the valve, a modulation of the fluid pressure controlling opening of said valve 12 is provided to constantly change the shape of sleeve 14.

It will be beneficial to provide this modulation 5 with a regulating escape type pneumatic mechanism associated with a balance of force beam 16 supporting mixer M on one side, and on the other side gauging .the escape of the pneumatic circuit supplying the valve, the escape taking place between beam end 16A and a nozzle 18 in a line 18A connect to pressure supply line 17 which is also connected to fluid intake line 15. Small motions of beam 16, induced by vibrations of mixer M resulting from turbine 5 motion, are picked up and transformed into signals through vibrations of beam 16 relative to nozzle 18. These vibrating signals modulate the regulating fluid15 pressure supplied to valve 12. This results in constantly varying the shape of elastic sleeve 14 of valve 12,' which prevents any plaster stagnation and therefore any setting of the mixture in the narrow channel of the valve.

In order to have a continuous process production of a liquid plaster/water mixture, with a determined fluidity Fo, one proceeds as follows. First a mixture ratio p2. giving a fluidity Fo is selected, Wo being water flow rate, Po being plaster powder flow rate, and is introduced into mixer M, Fo being a value expressed in mm (millimeters) given by F.L.S. test. This FLS test is frequently used fc}7 plaster manufacturers and it indicates plaster performance when poured. Xt consists in filling a hollow cylinder with a diameter of 60 mm (2.36 in.) and height of 59 mm (2.32 in.), placed vertically in the center of a polished metal or glass plate, with plaster mixed with water. At time t set in relation to time to of first contact between plaster and water, the cylinder is lifted thus freeing plaster which spreads on plate and forms a disc whose diameter is measured. The size of this diameter constitutes fluidity F parameter for time t.

Plaster powder and water supply flow rates in mixer M are set at Po and Wo. A time is selected of the stay To of 47823 nixed plaster in mixer M. The mixer outlet is closed.

Turbine 5 of mixer M is set in motion. Water is introduced in mixer M at flow rate Wo for time To, and then plaster is introduced at flow rate Po also for a length of time To starting with the shutoff of water supply. Then after mixing, at the same time the mixer water supply is set at flow rate Wo, and the plaster powder supply is set at flow rate Po, and the mixer outlet is opened to allow the mixture to run off, valve 12 being set for a run off flow rate so that the amount of product in mixer trough remains constant. Valve control fluid pressure modulation is provided by vibrations from the mixer M. Thus, a permanent running range is reached. A liquid mixture of plaster powder and water with a set fluidity FLS, measured at t = 1 minute 15 seconds, and which can be selected at a value as low as 120, can be used in the pouring facility of the invention to be described below. For more detail, reference may be had to our aforesaid copending applications.

The continuous process pouring facility, shown as a whole in Figures 1 and 2 includes mixture distribution components D, a pouring head C which makes it possible to spread out the plaster on the moving conveyor, and reinforcement introduction means R. Mixture distribution components D, placed after valve 12 below mixer M, include a receiving container 19 constructed as shown in Figures 3 or 16, a pump 20, a distributor 21 constructed as shown in Figure 4, and pipes 22 (Figure 1). Receiving container 19 creates a load break at the output of valve 12 and isolates the mixer from the downstream part of the facility so as to make it possible to weigh said mixer free of apparatus downstream of tube 23.

It is made with two vertical tubes 23 and 24, which are apart and placed on the same axis. Tube 23 passes freely through top 25A of case 25 and tube 24 forms a connection with bottom 26. The space between these two tubes 23 and 24 is enclosed in a case 25. Lower tube 24 penetrates into said case 24 above its bottom 26. A water intake pipe 27 ending in a .47025 spray nozzle 28 enters case 25 to wash out any plaster splashes. The lower part of bottom 26 of case 25 is provided with drain-off openings 29 for this wash water. Lower tube 24 brings the mixture to pump 20. Pump 20 is a pump able to operate without a load, capable of absorbing all flow from mixer M, compatible with a certain amount of accidental air circulation and capable of transmitting sufficient energy to the mixture in order to prevent mass setting inside the pipes in the system and able to work the load whatever it may be.

Thus it will be convenient to use a rotative pump with gears or cams, or a plastic pipe pump, whose pipe is compressed by rollers or by an eccentric cam pushing the mixture out to said pump output openings.

Pump 20 may be directly connected with pouring head C through a pipe 22. However, inasmuch as several pouring heads C (Figure 2) are supplied from one sole mixing uni-t and inasmuch as pump flow is always constant, a distributor 21 is placed at the outlet of pump 20 to regularize the flow and divide the mixture stream provided by pump 20 into many smaller and identical streams. Distributor 21 (Figure 4) is funnel shaped, connected through its smaller end to the outlet of pump 20, and with its wider end closed by a cover 31, with radial outlet or distributor tubes 32 starting from the top section of funnel wall, near cover 31. Preferably, in order to obtain identical divided streams, distributor tubes 32 are arranged symmetrically relatively to the funnel axis and the distributor is mounted with its axis vertical. In order to allow for more space, distributor tubes 32 are slanted down. A pipe 22 is connected to each arid every distributor tube 32 to bring the mixture to pouring head (or heads) C.

A typical multiple outlet distributor 21 for a flow rate of 60 Kg/mn has a funnel having a top diameter of 40 mm and a bottom diameter of 14 mm, and has 4 outlets each of a diameter of 8 mm. These outlets are slanted at 15° to the vertical.

The funnel is 40 mm high, and the outlet pipes are connected to the funnel at 10 mm lower than the enlarged top 31.

Figure 5 shows in detail pouring head C mounted above conveyor S; pouring head C and pouring bed S moving in relaticn to one another. For convenience, it is preferable to keep pouring head C and all its supply pipes stationary, and hence conveyor S is a moving conveyor. Conveyor S is made from, for example, a stainless metal strip or a rubber strip.

A pair of lateral strips 33 (Figure 2) with same movement as conveyor S are mounted vertically on either side of conveyor S.

Pouring head C (Figure 5) includes essentially two 10 obstructing plates 34 and 35 forming, with conveyor S and lateral strips 33, a reservoir in the form of a small trough 34A placed transversely in relation to the direction of motion of conveyor S, plate 34 being the downstream one and plate 35 being an upstream counter-plate, upstream and downstream being defined according to conveyor progress.

Downstream plate 34 is equipped, on its outward face with a series of supply tubes 36 distributed along all its width and passing through it to open into small trough 34A.

Each one of these supply tubes 36 is connected with a distributor tube 32, either one distributor tube 32 being connected with only one supply tube 36, or one distributor tube 32 linked through a Y connection 37 (Figure 5) to two supply tubes. Two distributor tubes 32 may be linked with only one supply tube 36. Preferably, the supply tubes 36 should be horizontally flared as they pass through obstructing upstream plate 34 to form distribution nozzles 36A. The height at which tubes 36 reach downstream plate 34, and their spacing in regard to one another are functions of operating conditions: mixture flow rate, mixture fluidity, and level of mixture inside the trough; in the same way, the distance between both plates 34 and 35 are a function of operating conditions. Downstream plate 34 is raised in relation to conveyor S in order to provide a slit whose height, adjustable, is at most equal to the projected plaster run thickness. Both plates are provided with lateral rubber flaps 38, which touch moving lateral strips 33. Upstream plate 35 has a gasket 39 in its lower part in order to insure tightness with conveyor S. Each plate 34 and 35 has a vibrator 40 mounted on its top, for instance a pneumatic vibrator, creating a vibration vertically at a right angle to the direction of motion of conveyor S. Each of the two plates 34 or 35 is secured by machine screws (not shown) through two fixed lateral grooves 41A on clamps 41 mounted on general facility frame (not shown). Either plate 34 or 35 can be moved at will along these two retaining grooves, independently from each other. Plates 34 and 35 are secured to brackets 41 through vertical elongated openings 43 in brackets 41 by screws 42A with.elastic stops 42 interposed between the plates and the brackets. Elongated holes 43 in the vertical portion of securing clamps 41 make it possible to adjust each of plates 34 and 35 in height, Downstream plate 34 may be fitted with a guide plate 44 (Figure 5) approximately at right angles with plane of plate 34 outside of the small trough 34A constituted by both plates and 35. Preferably this guide plate 44 is set at a low angle, about 7 degrees (°), divergent upwardly in relation with the direction of movement of conveyor S. Upstream plate may be equipped with a reinforcement plate 46 (Figure 5) making it possible to guide the introduction of a reinforcement 45 inside of or on top of plaster panels (Figure 2).

This plate 46 may be a flange (Figures 2 and 8A) on a slant mounted outside of the small trough, transversely in relation to conveyor S and linked with upstream obstructing plate 35 at the level of its lower rim. Thus, this guide 46 may be slanted about 45° in relation to conveyor S, depending on the reinforcement location in relation to obstructing plates. Reinforcement 45 could be available in rolls.

Another way to facilitate the introduction of a reinforcement may comprise a rounded padding shown at 47 (Figure 8B) covering the lower rim of upstream obstructing plate 35. An identical padding, shown at 47' on Figures 8C and 8G can be put on the lower rim of the downstream plate 34. One of independent reinforcement guides 46A, 48, 48A, 50, 49, 51 or 48 shown respectively in Figure 8 at D, E, F, Η, I, J and K 4783S respectively and not secured to the upstream plate 35 may be used. An independent guide, as the one shown at 49 in Figure 2 and 81 may include a curved slanted upstream section 49A identical to guide 46 mounted on upstream plate 35 of a pouring head C, a horizontal part 49B and a guide portion 49C with a very narrow upward angle of about 7° in relation to conveyor S and identical to guide plate 44 of a pouring head G.

In the case of the embodiment of Figure 8G, the reinforcement 45 is introduced tangentially to the rounded padding 47' and in this manner cleans it, thus keeping the opening between the padding 47' which forms the lower edge of the downstream plate and the conveyor constant.

An independent guide may be a sole slanted plate 50 (Figure 8H), curved, identical to plate 46 mounted on hack plate of a pouring head. An independent guide may also comprise a rounded padding 51 (Figure 8J) parallel to the conveyor and at a right angle in relation to its direction of progress either mounted on a plate 51A whose plane is parallel with the one of pouring head C as shown in Figure 8J, or by itself, made from a simple bar held at a distance from the conveyor equal to the height at which the introduction of the reinforcement within the manufactured products is desired as shown at 48, 48A and 48B in Figures 8E, 8F and 8K, respectively. Several guides of the above described types can be used at the same time to introduce several reinforcements at various levels into a plaster layer poured through one single pouring head. In addition, several pouring heads, with each of which one or several guides can he combined, can follow one another one on the same building panel manufacturing line; then, each pouring head C may be independent, as shown in Figure 2, or on the contrary dependent on ones following it, as shown in Figure 9, with the downstream plate of one pouring head constituting the upstream plate for the next head. Thus, it is possible to have one single pouring head C for building panels, or several successive pouring heads C each pouring a strip of a certain thickness, the first one directly on conveyor S, the next ones above the plaster strip already poured by the preceding head or heads. 8 25 The operation is as described below.

A fluid plaster mixture is obtained in mixer M, and its runnoff flow rate is regulated by regulating valve 12.

The mixture runs off through receiving container 19. Spray nozzle 28 throws water in order to wash away any plaster splashes from inside receiving container 19. This wash water drains off through drain openings.29. Since lower tube 24 opening is above bottom 26 inside of case 25, this wash water cannot mix with the mixture and does not cause any alteration of mixture proportions. In order to facilitate starting operations of plaster mixture preparation station, a phase during which slight variations of plaster fluidity can he recorded, it may then be desirable to drain off mixture away from the manufacturing line to prevent any mass setting in any place on the said line where not scheduled. At that time, flexible tube 23 coming from valve 12 is taken out of container 19 and directed toward the outside and put back into place when fluidity has stabilized. In normal operation, the mixture having passed through receiving container 19 is introduced into pump 20. Pump 20 makes it possible to pump mixture up to various positions where'it will be used, sometimes at distances of many tens of meters. Then, as the case may be, the mixture is either taken directly to a pouring head C, or sent to multiple outlet distributor 21. Inside distributor 21, the mixture runs first up’to cover 31 and. then it enters radial distributing tubes 32 evenly and continuously. The mixture passes through tubes 22 rapidly which prevents any mass setting inside said pipes and then it comes into supply tubes 36 where it is distributed into small trough 34A delimited by plate 34, 35, conveyor S and lateral strips 33, arriving in the direction opposite to .the direction of movement of conveyor S. Distributor 21 makes it possible to supply, from one single mixing station, with the same weight distribution, all the areas dependent from one pouring head whatever their width may be, makes it possible to split a single mixture stream into many smaller streams giving same total flow rate, makes it also possible to supply several pouring heads.

The mixture piles up in small trough 34A, thus creating a homogeneous storage load. Plaster streams coming through nozzles 36A of supply tubes 36 cross the trough, hit plate 35, are projected back and stream back toward downstream plate 34 and so on until they have exhausted their energy. Thus, they create vortices which stir up mixture and prevent formation of stagnant zones. .The spacing between supply tubes 36, plaster incoming speed and the height at which said supply tubes 36 are mounted, must be selected or adjusted so that this circular motion inside of the trough between downstream plate 34 and upstream plate 35 is preferrably immersed in the mixture but nevertheless affects the surface of the mixture and so that each flow line creating a circular motion out of a supply tube 36 and induced by the back and forth motion be joined to the next circular motion line from the adjacent tube 36 with no stagnant zone between the two lines. Any lack of motion of plaster in any part of the trough would create a lack of homogeneity of mixture which would be detrimental to the quality of manufactured product, would favor a mass setting which would spread out, and would end up obstructing the whole of the pouring head.

Nozzles 36A of supply tubes 36 are flared horizontally so that streams coming out of them provide a stirring distributed over a wider area, so that depth of stirring is limited, and so that splashing is prevented.

The watertightness of upstream plate 35 combined with conveyor S in motion is achieved with gasket 39, but it is beneficial, in order to prevent formation of stagnant zones in small trough corners close to said plate to allow for a slight leak underneath the plate. Thus a round fold forms in the back, which constantly forms again owing to continuous pouring bed progress, which contributes to perfecting of watertightness. Such a fold is shown at 46B in Figure 8D. Downstream obstructing plate 34 is raised on loosening 478 as screws 42A securing it to clamps 41 in order to provide between it and conveyor S a slit of height e. The stationary load upstream from the obstruction provided by plate 34, causes the mixture to spread on conveyor S through the slit thus created.

In the case of small thickness panels, it is preferable to use plate 44; said plate 44 then facilitates retention of the load inside of trough 34A and prevents, when the level in said trough is very low, stirring which takes place therein from spreading to the downstream side of plate 34. It is beneficial, in order to prevent plaster from forming deposits or from mass setting on plates 34, 35 to subject them to vertical vibrations at right angles.with conveyor S with vibrators 40.

For the adjustment of a pouring head C, the procedure is as follows. For a given speed of conveyor-, the dimensions of the board to be manufactured determine the amount of mixture to be supplied by the mixing station and to be poured on conveyor S, and therefore the total rate of flow at the outlet of supply tubes 36, as they discharge Into trough 34A. The section of each supply tube 36, size of nozzles 36A, number of supply tubes 36 and of pipes 22 are selected in order to obtain a speed, in said tubes and pipes, which does not allow deposits, i.e., in the case of plaster, a speed above 10 centimeters (3.94 inches) per second (cm/s) (in./sec.). The mixture is received into the trough 34A.

Slit height e is provided under downstream plate 34 and the distance between upstream plate 35 and downstream plate 34 is adjusted in order to achieve a constant level in the trough, a satisfactory agitation, and.the immersion of the tubes 36 in the mixture in the trough. Agitation of the mixture in the comers of upsteam plate 35 is achieved by raising slightly said plate in order to create a round fold about 5 centimeters (2 inches) long at its middle.

The table below gives, by way of example, two series of operating parameters for a pouring head. 47835 Example 1 Example 2 Speed of conveyor in meters (feet) per minute 2.50 (3.22) 2.50 (8.22) Mixture FLS in millimeters (inches) 230 (9) 230 (9) Pouring head supply tubes diameter cm. (in.) 8 (.3) 10 (.39) 5 Nunber of supply tubes per head 4 4 . Width and height of discharge opening of supply tube nozzles 12 4 15 5 Spacing of outlets through front plate, cm (in.) 83-150-150-150-83 83-150-150-150 10 Height above conveyor at idiich these (3.27) (5.91) outlets are placed ma (in.) 13 (.51) 17 (.66) Pouring head width mm (in.) 616 (24.25) 616 (24.25) Distance between upsteam plate and dcwn- stream plate ma (in.) 90 (3.54) 110 (4.33) 15 Mixture height in small trough ma (in.) 15 (.59) 20 (.79) Height of round fold under back plate cm (in.) 2.5 (.098) 2.5 (.098) Pouring slit e height mn (in.) above conveyor 4 (.15) 8 (-31) Thickness of panels thus manufactured ma (in.) 5 (.20) 10 (.39) When there is a succession of pouring heads, as shown in Figure 2, they are adjusted separately and in the same way, inasmuch as they are independent.

With the pouring heads joined to one another, as shown in Figure 9, the most upstream pouring head is adjusted first, and then the next pouring head, the pouring slit height for one head being at the same time the round fold height for the next head, in this manner building a component 60 of, for example, a plaster board having layers 62, 64 and 66 of the same or different densities. When several pouring heads C follow one another, they may all be supplied with same product or supplied with plaster mixtures of various different densities and/or with different finely split or chopped reinforcement fibers, which are introduced at the mixing time.

One or several reinforcements 45 may be introduced in manufactured boards at various levels in their body and at various positions on the manufacturing line. Under the term reinforcement, we define all materials which can be set inside of boards or on their surface, whether they actually serve as reinforcement to increase said boards resistance to applied forces or whether they constitute either decorative or - 15 4-78 2 5 protective lagging. Not only may strip or continuous reinforcement be introduced, but also other non-continuous reinforcements, such as chopped or finely split fibers, may be introduced. Exemplary reinforcements are paper, cardboard, metallic film such as aluminum sheet, glass cloth, fabrics, non-woven organic materials, continuous threads, for example, of glass or wires, continuous·thread sheets intermixed with glass, layers of criss+crossed continuous glass threads, or others. These reinforcements,may be introduced upstream from a pouring head using independent guides as shown in Figures 8D and 8E. For instance, reinforcement material 45 supplied in rolls is stretched up to a guide, passed between said guide and conveyor S and placed underneath pouring head C.

As it is caught in the plaster it is drawn away, and a continuous pulling is exerted on the roll which thus unwinds at manufacturing line speed. In this way a reinforcement can be placed, either on the bottom face of the manufactured board panel by securing the guide very close to the conveyor, or in the body of the board by securing the guide at a distance from the conveyor equal to the height at which the reinforcement is scheduled to be placed in the board, the distance being, however, not exceeding the smallest height at which upstream plate 35 and downstream plate 34 have been raised in relation to the conveyor. Several reinforcements can similarly be introduced at various heights with several independent guides set upstream from a pouring head. Also, reinforcements may be placed on the bottom face of the board or in its body by guiding them through guides 46 and 47 secured on upstream plate 35 as shown in Figures 8A and 8B, the height of the reinforcement in the body of the board being, however, limited by the pouring slit height underneath the downstream plate. A guide 47' (Figure 8C) may also be secured to downstream plate 34 and then the reinforcement height is determined by the slit height underneath downstream plate 34.

Reinforcement may also be introduced inside of the trough between downstream 34 and upstream 35 plates. Reinforcement height can then be determined through bar shaped guide 48 as shown in Figure 8F or through round padding 47' set on the downstream plate (Figure 8G). A reinforcement introduced through this process must be the most pervious possible to plaster in order to least interfere with agitation inside of the trough.

Reinforcement may also be introduced after the plaster layer has been poured, either on the surface or in the body of the plaster, through an independent guide 50, 49, 51 or 48B set downstream from the pouring head as shown respectively in Figure 8H, I, J, K. When the reinforcement is set on the surface of a layer, it can be either porous or watertight to the plaster fluid mixture. When it is set in a plaster layer mass, it would be preferable for it to be porous to allow the fluid mixture to permeate through it; to prevent the reinforced board from tending to split along the reinforcement plane. Layers of criss-crossed continuous wires or threads may be used, in order to provide for a satisfactory distribution of reinforcement throughout the plaster mass of the board, a good cohesiveness between plaster and reinforcement, and for the reinforcement to be easily passed through by plaster at the time of its placement.

Once poured, the plaster strip progresses on the conveyor S, framed in by lateral strips 33, until the plaster has set sufficiently to be handled and cut up. Then the strip passes to another conveyor. Conveyor S and lateral strips 33 are washed off during their return travel.

As already known, it will be possible to intervene on various plaster reaction phases by adding either before or after pouring setting delaying or accelerating agents. The temperature of conveyor S can also be acted upon.

Products manufactured by the above described process and apparatus may be plaster alone, or plaster reinforced by glass fiber, for instance; they may be used by themselves or be combined with other materials to be used as a covering layer or as ornamental plates. They can be made into thin plaster panels less than 3 mm (.118 in.) thick reinforced with or without continuous fiber glass, or made into thicker panels with a reinforcement to improve resistance, or made without any reinforcement, and may be covered or not with lagging.

It is possible to pou,r a very thin plaster film down to about one millimeter (.039 in.) thick to be used to cover the bottom and sides of ceiling panels made of fiberglass. In that case, it is possible to place upon the plaster film just poured a . glass wool strip just downstream from the pouring head, the plaster itself providing for linkage with the glass wool at the time of setting, or the glass wool itself can be the pouring bed. Such a board 90 is shown in Figure 20 and includes a plaster board sheet 92 attached to a glass wool. pad 94.

Plaster boards thicker than one centimeter (.39 in.) may be used as ornamental boards to build sheath partitions.

Up to now such partitions were made with a glass wool board with an asphalt agglomerated paper vapor harrier and a reinforced plaster plate with a cardboard top layer. From now on, as an application of the invention process, a partition can be made with a glass wool panel without a vapor barrier and thus without any asphalt and a plaster plate reinforced with fiber glass without any cardboard top layer, the junction between the glass wool and plaster being provided through gluing or preferably by the plaster itself fastened to the glass fibers during its setting. Such sheath partitions offer improved fire-retardant properties compared to older partitions because they eliminate the paper cover sheets which are a fire hazard. The invention process and apparatus make it possible not only to pour plaster, but also other evolutive products, i.e., products with changing physical or chemical properties, and all non-evolutive products such as cement.

A completed plaster board panel 100 made using the process and apparatus described above is shown in Figure 10 .47825 and is suitable, for example, for use in building construction.

As shown in Figure 11, a plaster board 102 has layers 104, 106 and 108 with each layer having a density different from the densities of the other two layers. Thus, for example, the densities of layers 104, 106 and 108 may be 1000 kg/m3, 200 kg/m3, and 800 kg/m3, respectively, the 3 densities may be regulated between 150 kg/m to 2000 kg/m by adding a forming agent as known in the prior art.

Referring to Figure .12, a plaster board 112 has layers 114, 116 and 118. Each layer has a density different from either of the other two layers, for example, layers 114, 116 and 118 having densities of 800 kg/m3, 300 kg/m?, and 900 kg/m , respectively. A fabric reinforcement sheet 120 lies between layers 114 and 116. Similarly, a fabric reinforcement sheet 122 lies between layers 116 and 118. Sheets 120 and 122 are sufficiently porous so that plaster can · penetrate the interstices between the threads forming the fabrics.

A plaster board 126 shown in Figure 13 has embedded in the central portion thereof a fabric reinforcement sheet 128 of, for example, fiberglass.

Referring now to Figure 14, a panel 132 comprises a plaster board 134 and a fiberglass mat facing 136 on said board with the fibers 138 of mat 136 embedded in board 134 and shown on an enlarged scale.

In Figure 15, there is shown a plaster board 142 having layers 144, 146 and 148 of plaster with layers 144 and 148 being reinforced by thin sheets of aluminum 150 and 152 respectively.

All of the foregoing and numerous variations thereof are readily made using the apparatus and process described above and are useful, for example, as building elements.

A preferred receiving container 200 which can be substituted for receiving container 19 is shown in Figure 16. Container 200 has an open top 202 and receives discharge from tube 23 which has a valve 204 used to shut off flow from the mixer M during the start up operation, permitting the setting of valve 12 to remain undisturbed from the previous operation if manually operated or to remain connected to automatic valve setting means responsive, for example, to the weight of the mixer M. The receiving container 200, being physically disconnected from mixer M while providing for continuity of flow, permits mixer M to be weighed so as to determine the amount of material contained therein.

In the embodiment of Figure 16 tube 24 has a funnel 206 connected to its upper end to collect the discharge from tube 23. Funnel 206 insures the collection of any portions of the stream discharging from tube 23 which expand beyond the diameter of tube 23 when discharged.

As shown in Figure 17, pouring head 3 has a vertical upstream plate 220 and a curved downstream plate 222 having a rounded bottom edge 224 against which runs reinforcement 45 to keep plate 222 clean including bottom edge 224 and to keep the distance between plate 222 and conveyor 226 constant.

As shown in Figure 13, a desirable plaster board 240 has a reinforcement layer of continuous filament mat 242 with layers of glass fiber netting 244 and 246 above and below, respectively, to confine the layer 242 and restrain it from spreading apart. This plaster board is advantageous because the mat 242 makes the board very strong. ’ As shown in Figure 19, a plasterboard 250 has a reinforcement layer of chopped glass fibers 252 between an upper glass fiber netting layer 254 and a lower glass fiber netting layer 256. This board is advantageous because the chopped fibers are less expensive than mat 242 and yet give the board 250 great strength. The netting 254 and 256 confine the glass fibers 252 and prevent them from escaping from the board and from extending sideways from the side edges of the board 250. This is very important, expecially for thin board.

Claims (5)

1. A process for the manufacture of a band or boards of plaster by casting on a movable casting bed travelling at uniform velocity a mixture essentially of plaster 5 and water contained in a reservoir placed directly over the casting bed at a pressure head with respect ..to . said casting bed, said mixture being cast through a transverse slot which is parallel and adjacent to the casting bed and formed under the downstream wall of said reservoir, 10 in which replacement mixture is continuously introduced in liquid form into the reservoir by a plurality of jets immersed in the mass of mixture already in the reservoir, which jets are spaced apart in such a manner and have such force that they produce in the mixture of the 15 reservoir an agitation the flow lines of which are visible over the whole surface of the reservoir.

2. A process according to Claim 1, in which the jets are situated side by side horizontally and directed approximately horizontally in the opposite sense to that 20 of the displacement of the casting bed. .

3. A process according to any one of the preceding Claims, in which the slot is at a height at least equal to the thickness of the boards or the band. 4. 7 8 2 8 within the thickness of the boards of product produced, the front wall and rear wall of the reservoir being raised above the casting bed at distances at least equal to this height at which the reinforcement is positioned. 5 15. A process according to any one of the preceding Claims, in which at least one reinforcement is brought into the reservoir of product between the upstream wall and downstream wall of said reservoir and is introduced into the casting slot under said downstream wall, the said 10 reinforcement being carried along by the cast product in the direction of travel of the casting bed. 16. A process according to Claim 15, in which a reinforcement is introduced in contact with at least the lower edge of the front wall of the reservoir, the 15 height of the casting slot under said plate being equal to the height at which said reinforcement is positioned within the thickness of the boards of product produced. 17. A process according to Claim 16, in which the reinforcement is kept in contact with the front wall 20 so as to clean it. 18. A process according to Claim 15, in which the reinforcement is positioned inside the reservoir at a distance from the casting bed corresponding to the height at which the reinforcement is to be positioned 25 within the thickness of the boards of product produced, the height of the slot under the front wall of the reservoir being at least equal to the height at which said reinforcement is positioned within the thickness of the boards of product. 19. A process according to any one of the preceding Claims, in which another reinforcement is introduced into the layer of cast product by application of the said reinforcement to the upper surface of said layer which has already been cast and by embedding of said reinforcement within the thickness of said layer at the height at which the said other reinforcement is desired to be placed within the 'thickness of the manufactured board, said other reinforcement being carried along by the cast product in the direction of travel of the casting bed. 20. A process according to any one of the preceding Claims, in which several layers of product are oast successively on the same production line of boards or of a band, the first layer being cast directly on the casting bed while the one or more than one subsequent layer is cast on the one or more than one layer already cast, each of which layers may have one or more than one reinforcement. 21. Apparatus for the manufacture of a band or boards of plaster by casting a mixture essentially containing water and plaster, comprising a bottomless trough resting on a movable casting bed and having an opening bounded by said casting bed and by the lower edge of the plate which forms the downstream wall of the trough, 5 in which said downstream plate is eguipped with a plurality of feed tubes for mixture, which tubes are distributed over the whole length of said downstream plate on the outside of the trough and pass through the downstream plate to open into the interior of said trough 10 and are connected to devices which supply energy to the mixture of plaster and water. 22. Apparatus according to Claim 21, in which the feed tubes are parallel immediately before they pass through the downstream plate of the trough. 15 23. Apparatus according to any one of Claims 21 or 22, in which the ends of the feed tubes adjacent to the downstream plate of the trough lie in the same horizontal plane. 24. Apparatus according to any one of Claims 21 to 20 23, in which the trough is formed by two plates arranged vertically perpendicularly to the direction of travel of the casting bed, namely a downstream plate and an upstream plate and by two movable lateral belts having the same movement as the casting bed and bearing 25 against the ends of the downstream and upstream plates. 25. Apparatus according to Claim 24, in which the downstrear. plate is attached to the general structure of the installation by right-angled brackets having oblong assembly apertures for adjustment of its height. 26. Apparatus according to any one of Claims 24 to 25, in which the upstream plate is attached to the general structure of the installation by right-angled brackets having oblong assembly apertures for adjustment of its height. 27. Apparatus according to any one of Claims 24 to 26, in which the upstream plate of the trough is mounted to be adjustable in position in the direction of travel of the casting bed. 28. Apparatus according to any one of Claims 24 to 27, in which the downstream and upstream plates of the troucrh are equipped with vibrators. 29. Apparatus according to any one of Claims 24 to 28, in which the ends of the feed tubes connected to the downstream plate widen out laterally. 30. Apparatus according to any one of Claims 20 to 29, in which the downstream plate of the trough is equipped with a guide blade outside the trough, connected to said downstream plate at the level of the lower edge thereof and approximately parallel to the casting bed, the outer edge of said blade being never lower than its 4782S other, parallel edge connected to the downstream plate. 31. Apparatus according to any one of Claims 20 to 30, in which the means for supplying energy to the mixture include a pump. 5 32. Apparatus according to any one of Claims 20 to 31, in which the feed tubes are directly connected to a multiple outlet distributor in the form of a hopper connected by its narrow end to the product inlet and having a cover on its wide end and radial outlet tubes 10 situated close to the cover. 33. Apparatus according to any one of Claims 20 to 32, which comprises a plurality of troughs arranged side by side in the direction of travel of the casting bed. 34. Apparatus according to any one of Claims 20 to 15 33, provided with means for the introduction of a reinforcing material into the boards of product produced, comprising a roll of said reinforcing material and at least one positioner for the reinforcement. 35. Apparatus according to Claim 34, in which the 20 positioner is a smooth, curved plate arranged above the casting bed and inclined to said casting bed at an angle initially greater than and then approximately equal to the angle which the reinforcement makes with the casting bed when the reinforcement is stretched out between the 25 roller and the location on the casting bed where the reinforcement is introduced into the cast product. 36. Apparatus according to Claim 34, in which the positioner is a round padding fixed above the casting bed parallel to said bed and perpendicular to its direction of travel at a level such that its lower edge is situated at the height at which the reinforcement is to be positioned within the thickness of the boards of product manufactured. 37. Apparatus according to any one of Claims 35 or 36, in which the positioner is carried on the upstream plate of the trough. 38. Apparatus according to Claim 36, in which the positioner is carried on the downstream plate of the trough. 39. Apparatus according to Claim 38, in which the downstream plate of the trough is slightly curved so that the reinforcement, guided by the padding situated on the lower edge of said plate, also bears against the surface of the plate. 40. Apparatus according to any one of Claims 35 or 36, in which the positioner is independent of the plates of the trough; it is situated in front of or behind the said trough and is fixed to the lower end of a vertical wall which is perpendicular to the direction of travel of the casting bed. 41. Apparatus according to Claim 35, in which the positioner is independent of the plates of the trough and in which it is integral with a horizontal wall and with a guide blade, the positioner being upstream of the 5 horizontal wall which in turn is upstream of the guide blade, and in which said positioner is placed at a height in relation to the casting bed equal to that at which it is desired to place the reinforcement in the board of cast product. 10 42. A construction element containing plaster, in which the plaster is employed by the process according to any one of Claims 1 to 20. 43 A construction element according to Claim 42, which comprises several layers of plaster of differing 15 densities. 44. A construction element according to Claim 41, which comprises a reinforcement at the separation between two layers of different densities. 45. A construction element according to any one of 20 Claims 42 to 44, which comprises at least one reinforcement, the reinforcement occupying one of the following positions: on the upper surface of the manufactured panel, on the lower surface, close to the upper or lower surface, embedded in the thickness of the panel. 25 46. A construction element according to any one of Claims 44 or 45, in which the reinforcement is a material belonging to the group of the following materials: paper, cardboard, metal film, glass foil, woven fabric, non-woven organic fabric, continuous threads, sheet of matted continuous glass threads. 47. A construction element according to any one of Claims 42 to 46, which comprises a plaster board having a thickness less than 3 mm. 48 A construction element according to any one of Claims 42 to 47, which comprises a plaster board within the thickness of which is situated a web of matted continuous glass threads enclosed above and below by a mesh of glass threads. 49. A construction element according to any one of Claims 42 to 47, which comprises a plaster board reinforced by chopped glass fibres enclosed above and below by a mesh of glass threads. 50. A construction element according to any one of Claims 42 to 49, which is formed by at least one facing board of plaster and a board of some other material, in particular glass wool, the board of glass wool adhering to the plaster facing by the plaster setting around the fibres of the glass wool in contact with the plaster. 51. A process for the manufacture of a band or 4782S boards of plaster, substantially as herein described with reference to the accompanying drawings. 52. Apparatus for the manufacture of a band or boards of plaster, substantially as herein described with

'4. A process according to any one of the preceding 25 Claims, in which the jets arrive with such force that they produce in the mass of mixture of the reservoir an agitation along lines of flow in the form of a forward and return path. 5. A process according to Claim 4, in which the 5 space between the jets arriving in the reservoir is such that the lines of agitation produced by all the jets are contiguous. 6. A process according to any one of Claims 4 or 5, in which the height at which the jets enter the reservoir 10 is such that the lines of flow resulting from the agitation are level with the free surface of the mixture of the reservoir. 7. A process according to any one of the preceding Claims, in which the mixture contained in the reservoir 15 has a fluidity FLS greater than 120. 8. A process according to any one of the preceding Claims, in which the walls of the reservoir are subjected to vibrations. 9. A process according to Claim 8, in which the 20 vibrations to which the walls of the reservoir are subjected are perpendicular to the direction of travel of the casting bed. 10. A process according to any one of the preceding Claims, in which the upstream wall of the reservoir is 25 raised to a certain height above the casting bed to enable a heel of product to be formed at the rear of the reservoir. 11. A process according to Claim 10,in which at least one reinforcement is introduced under the upstream wall of the reservoir, in the heel of product formed at the rear of said reservoir, the said reinforcement being then entrained by the cast product in the direction of travel of the casting bed. 12. A process according to Claim 11, in which the reinforcement is introduced in contact with the rear wall of the reservoir, said wall being raised above the casting bed by an amount equal to the height to which the said reinforcement is required to be placed within the thickness of the boards of product produced. 13. A process according to Claim 11, in which the reinforcement is introduced in contact with the downstream wall of the reservoir, the height of the slot under said wall being equal to the height at which said reinforcement is positioned in the thickness of the boards of product produced and the rear wall of the reservoir being raised at least as high as the front wall. 14. A process according to Claim 11, in which the reinforcement is introduced into the heel at the rear of the reservoir at a distance from the casting bed equal to the height at which said reinforcement is positioned

5. Reference to and as shown in the accompanying drawings.