FR2525520A1 - Controlled hopper installation for tile mfg. plant - uses weighing machine computer to generate compensating signal for vibrators servo control loop - Google Patents

Abstract

A hopper (8) containing powdered plaster is mounted in a frame (31) of a weighing machine (37) using strain gauges. The hopper is located over a vibrating platform (9) which is inclined towards the conveyor. On the discharging edge (27) of the platform are distribution plates (30) one of which (30a) is adjustable to allow the powder to be distributed evenly when the vibrator (33) acts on the platform. The vibrator is controlled from a comparator (35) which receives an input from a probe (34) on the platform and also from a potentiometer (36) to servo control the vibrator frequency. The moisture content of the plaster and the granule size are compensated for by signals from the weighing machine processor.

Description

The present invention relates to an installation for the manufacture of elements, in particular of construction, such as plates, tiles, etc. in a curable binder such as plaster or the like.

Installations for the continuous production of elements of this kind are already known. These known installations comprise a long, endless conveyor, at an upstream point from which tempered plaster is continuously poured, possibly containing starch-based glue, as well as devices for continuously feeding strips of paper and at least one rolling and forming device with rollers. Thanks to such an arrangement, a flat continuous plaster ply is obtained coated on its faces with adherent strips of paper, thanks to the presence of glue in the plaster, this glue tending to migrate outwards as the plaster drying. This continuous rod is then, after taking the plaster, cut transversely to its direction of travel to form the desired plates or tiles. In such installations, it is necessary that the mass of tempered plaster poured onto the endless conveyor is very malleable in order can be formed by rolling. This is obtained by adding a large amount of water to the plaster powder, at the time of mixing.

In the mess of plaster, there is about a part of water for a part of powdered plaster.

This large proportion of water, very much in excess for setting the plaster, has the effect on the one hand of increasing the setting time, that is to say in reality of requiring a very long conveyor, since the cutting of the continuous sausage in individual elements can only be carried out after the plaster is set. On the other hand, the individual elements thus produced are heavily charged with water (from 75 to 100% water by weight relative to the weight of plaster) and it is necessary to expend a lot of energy to dry them (to bring the water content around 15%). Such drying is obtained by passing through a tunnel oven which is arranged downstream of said endless conveyor and whose length is close to that of the latter, despite the passage of a plurality of plates arranged frontally.

This excess water therefore results in high expenditure on equipment (long length of the endless conveyor and the presence of a long drying time) and on energy (drying of the manufactured elements). As a result, the cost price of the elements thus manufactured is high.

The object of the present invention is to remedy these drawbacks.

It makes it possible to obtain construction elements of the type mentioned above at lower cost prices, thanks to considerable reductions in expenditure on material, labor and energy. These savings in material, labor and energy are possible, because, according to the invention, it is possible to use to form the elements that a very small amount of water (from 15 to 50% by weight so that drying must remove from 0 to 35% of water), which makes it possible to remove the drying device from known installations or at least to provide it with less power, and therefore to facilitate monitoring and maintenance of the installation and lower the installation cost.

To this end, according to the invention, the installation for the continuous manufacture of elements in a hardenable binder, such as plaster, with the addition of a liquid, in which said elements are obtained by successive elementary deposits of the dry binder in powder on a movable surface, each elementary spite being followed by wetting using a wetting device and each elementary deposit being carried out by sprinkling an amount of dry binder in powder metered as a function of the speed of movement of said movable surface and delivered by a dry binder distributor, is remarkable in that each dry binder distributor comprises a vibrating plate or the like, vibrated by a vibrator whose frequency is controlled by a set point, at constant amplitude of vibration.

Thus, it is possible to control the dusting rate from the plate by controlling the vibration frequency of the vibrator.

According to the invention, it is therefore possible to obtain with precision the thickness of each elementary deposit and therefore to determine the precise quantity of water to be sprayed on the elementary deposit. It is therefore possible, thanks to the invention, to best adjust the amount of liquid used.

According to an advantageous embodiment of the invention, to take into account more possible variations in particle size and humidity of the dry binder supplied to the plates, means are provided capable of determining the mass of binder supplied to each plate by periods of determined times and act on the vibrator servo setpoint, so that the binder flow delivered by the vibrating plates remains constant.

Preferably, each vibrating plate is inclined in the direction of the movable surface and has a discharge edge transverse to the direction of movement of this movable surface. In order to counteract the possible effects of the formation of harmonics on the plates, the pouring edge of the plaster is provided with juxtaposed overflow plates, at least substantially vertical defining by their upper edges a variable pouring line, capable of standardizing the flow of the linking transversely to the direction of movement of the movable surface. Preferably, the upper edges of said plates form an at least approximately continuous line, without sharp slots between two consecutive plates.

Each uniform deposit of dry powder binder can have a thickness of between approximately 0.1 and 10 mm and is carried out by dusting, with a drop height for example at least equal to 1 cm. In addition, each wetting is preferably carried out by spraying with an initial horizontal direction, so that the particles of wetting liquid were of a low height by gravity on the elementary deposits of binder. Thus, deposits and wetting are carried out gently, which promotes the quality of the products obtained.

The installation according to the invention may include means for placing on the movable surface, a support integral with the latter in movement and intended to receive the deposits of binder for the formation of said tube and means for gluing the interface. between said deposit support and this rod. Such a support can, for example, be constituted by a strip of paper, a strip or plates of insulating material, etc. The installation according to the invention can also include means for placing a coating on the upper face of said sausage, means for gluing the interface between the coating and the sausage and means for laminating said sausage provided with its coating. Such a coating can also consist of a strip of paper, a strip or plates of insulating material, etc.

Optionally, in order to standardize the upper face of the tube, a layer of a plaster and water mess is deposited on the last elementary wet deposit.

Preferably, the deposition of said mess takes place simultaneously with the installation of the upper covering.

In addition, when it is necessary to introduce a two-component reactive product, for example a foaming agent, into the plaster rod, it is advantageous to add one of said components to the wetting liquid sprayed by the wetting devices. of odd rank and the other of said components to the wetting liquid sprayed by the wetting devices of even rank.

The figures of the appended drawing will make it clear how the invention can be implemented. They show by way of illustration and not by way of limitation particular examples of implementation of the invention.

Figure 1 schematically and partially illustrates an installation according to the invention for obtaining a smooth product on its large opposite faces.

Figure 2 schematically illustrates the dosage of the dry binder.

Figure 3 is a front view of the device of Figure 2.

In these figures, identical references designate similar elements.

The installation shown diagrammatically in FIG. 1 comprises an endless band 1, the upper strand 2 of which moves from the left to the right of said figure and serves as a mobile support surface.

A strip of paper 3, coming from a reel 4, is applied to the conveyor 2 and is forced to move with it. Before its application to the conveyor 2, the paper strip 3 is glued on its upper face opposite the conveyor 2, by a glue device 5.

Above the conveyor 2 is arranged a plurality of pairs each comprising a distributor of dry plaster powder 6 and a water spraying device 7, and arranged one after the other along the said conveyor 2 In each pair, the water spraying device 7 is located downstream (relative to the direction of advance of the conveyor) relative to the plaster distributor 6 and each spraying device 7 extends transversely to the strip. of paper 3, over its entire width and projects the water droplets substantially parallel to the strand 2 of the conveyor 1, as indicated schematically by dotted lines 7a in the figure. Each plaster distributor 6 can be constituted by example by a hopper 8 containing dry plaster and the distribution opening of which is a slit transverse to the strip 3, formed at the lower part of the hopper 8, above a vibrating plate 9, transverse to the strip 3 As will be seen below, the flow rate of the plaster distributed by the distributor 6 is adjustable by the frequency of vibration of the plate 9.

Thus, the paper strip 3 scrolling continuously under the couples 6,7 thanks to the conveyor 2, the first distributor 6 (the one which is most upstream) deposits on the paper strip 3 a first uniform elementary layer 10 of plaster dry powder, on which the first spray device 7 (the one which is most upstream, immediately after the first dispenser 6) uniformly, but indirectly, sprays simple water or additives. On the elementary plaster layer 10 thus moistened and not yet set, the second distributor 6, immediately downstream of the first spray device 7, deposits a second uniform elementary layer of dry plaster powder, so as to obtain the thicker layer 11.On this layer 11, the second spray device 7 uniformly sprays water, simple or with additives.

The same operations are repeated as above for each pair 6.7, so that downstream of all of said pairs 6.7, a thick layer 20 is obtained formed by successive deposits of layers of elementary dry plaster, deposits each of which of them is immediately followed by wetting, the alternation of deposits and wetting being such that a deposit of dry plaster powder is always carried out on a layer of wet elementary plaster not yet taken.

Then, on the upper face of the thick layer 20 is applied a strip of paper 21, coming from a reel 22 and previously glued on its face directed towards the thick layer 29 by a sizing device 23. The application of the strip of glued paper 21 on the thick layer 20 is obtained by the intermediary ~ of a pressing device 24, making it possible to flatten the upper face of the layer 20 and serving as a rolling mill for adjusting the thickness of the latter. A flat plaster strand 26 is thus obtained which sets while advancing. Optionally, preferably at the pressing device 24, a waste of plaster and water, symbolized by the arrow 25, is deposited on the thick layer 20.

As soon as the flat rod 26 has taken hold, it is cut in known manner into sections, each of which forms a construction element such as a tile, a plate, etc. these sections not always requiring passage through a device. special drying before further use.

As soon as the flange 26 or the sections obtained by cutting it have taken hold, it is possible to machine them, for example to make ribs and / or embedding grooves in their edges. Such machining can be carried out by cutting tools (not shown) arranged at a stationary position along the path of the movable table 2.

Figures 2 and 3 illustrate how the dry binder is deposited on the paper 3.

The vibrating plates 9 are inclined towards the strand 2 of the conveyor and have a discharge edge 27 transverse to said strand. On this discharge edge 27 are arranged juxtaposed overflow plates 30, the upper edge of which is oblique to form a variable overflow line 30a, making it possible to uniformly transverse the discharge of powder binder, taking account of the bellies and the nodes vibration plate 9.

Each plate 9 is connected to the frame 31 of the machine by elastic connections 32 and is vibrated by an electric, pneumatic or other vibrator 33.

The vibrator 33 is of the type in which the amplitude of vibration is adjustable, when stopped, for example by modification of weights. Thus, to a vibration amplitude and to a given vibration frequency band corresponds a plaster flow and the control of this flow to a predetermined value is obtained by means of the vibration frequency. When it is desired to change the plaster flow, the weights are changed when stopped and the flow is slaved to its new value, always by means of frequency control.

At constant vibration amplitude, a probe 34 integral in vibration with the plate 9 measures the actual vibration frequency of the latter and transforms it into an electric quantity (current, voltage), which is representative of such frequency and which is transmitted to a comparator 35. This receives
moreover, from a device 36, for example a potentiometer, a reference value representative of a reference frequency for the vibrator 33, which is controlled by the comparator output 35. Thus, the frequency of the vibrator 33, and therefore that of the plate 9, can be slaved to the set value generated by the device 36 and displayed by the latter.

In order to take account of the variations in humidity and particle size of the dry binder located in the hoppers 8, these are connected to the frame 31 of the machine by a weighing device 37, for example a device with strain gauges. The indications of the device 37 are transmitted to a calculation device 38, which determines the variation in mass AM of the content in dry binder of the hopper 8 as a function of a duration AT, for example 10 or 20 seconds. Device 38 compares the value
LT thus obtained at a desired and displayed value K and controls the device 36 via an actuator 39 to modify the set value delivered by the device 36 to the comparator 35, so that the value - remains constantly equal to K .

dP
It can thus be seen that the flow rate of dry binder is controlled both by the vibration frequency of the plate 9 and by the variation of the setpoint, causing the frequency control. Thanks to this device according to the invention, one can take into account all the parameters likely to influence the dry binder flow rate.

In the case where it is desired to incorporate a foaming agent into the flange 20, for example, CO3NaH can be added to the water of the sprayers 7 of rank 1,3,5 etc ... and
HCl with water from sprayers 7 of row 2,4,6 etc ...

Thus, CO2 is produced in a staggered manner as a foaming agent.

Of course, the present invention is not limited to the examples of implementation described above.

Although examples have been described above of implementation of the method according to the invention suggesting that the elements or tubes obtained have a flattened rectangular section, it goes without saying that the present invention is not limited to the obtaining tubes or elements having such a section. Indeed, by adjusting the support surface of the deposits and / or the distribution of the binder, as well as possibly having covers, shims, stops, etc. it is possible to obtain strands or elements of any desired section.

Claims (8)

1.- Installation for the continuous manufacture of elements made of a curable binder, such as plaster, with the addition of a liquid, in which said elements are obtained by successive elementary deposits of the dry binder powder on a mobile surface, each deposit elementary being followed by wetting using a wetting device and each elementary deposition being carried out by sprinkling with a quantity of dry binder in powder metered as a function of the speed of movement of said movable surface and delivered by a dry binder distributor, characterized in that each dry binder distributor (6) comprises a vibrating plate or the like (9), vibrated by a vibrator (33) whose frequency is controlled by a setpoint (36), with amplitude of vibration constant 2.- Installation according to claim 1, characterized in that the binding rate of each vibrating plate is determined for a vibration amplitude and a given frequency band of the corresponding vibrator, the cha Changing the value of the flow rate by changing the amplitude and controlling the value of a given flow rate by controlling the frequency. 3.- Installation according to one of claims 1 or 2, characterized in that it comprises means (38,39) capable of determining the mass of binder supplied to the plate by determined time periods and of acting on the servo setpoint (36) of the vibrator (33), so that the binder flow delivered by the vibrating plates remains constant. 4.- Installation according to one of claims 1 to 3, characterized in that each vibrating plate (9) is inclined towards the movable surface (2) and has a discharge edge (27) transverse to the direction of displacement of this mobile surface. 5.- Installation according to claim 4, characterized in that the discharge edge (27) of the plates is provided with overflow plates (30) juxtaposed at least substantially vertical, defining by their upper edges, a variable discharge line (30a ), suitable for standardizing the flow rate of the binder transversely to the direction of movement of the mobile surface (2). 6.- Installation according to claim 5, characterized in that the upper edges of said plates (30) form a line (30a) at least approximately continuous, without sharp slots between two consecutive plates. 7.- Installation according to any one of claims 1 to 6, characterized in that the wetting devices (7) emit sprays of liquids having an initial direction at least substantially parallel to said movable surface (2). 8.- Installation according to any one of claims 1 to 7, characterized in that, in order to standardize the upper face of the flange (20), is deposited at 25 on the last wet elementary deposit, a layer of a mess plaster and water. 9.- Installation according to claim 8, comprising means for placing a coating on the upper face of said tube, means for gluing the interface between the coating and the tube and means for laminating said tube provided with its coating, characterized in that the deposition of said mess takes place simultaneously with the installation of the upper covering.  10.- Installation according to any one of claims ia 9, characterized in that, when it is necessary to introduce into the plaster rod a reactive product with two components, for example a foaming agent, one adds said components to the wetting liquid sprayed by the wetting devices (7) of odd rank and the other of said components to the wetting liquid sprayed by the wetting devices of even rank.