Method and device for manufacturing a plasterboard

Abstract

In manufacturing a plasterboard, it is known to provide a facer (7) and move it in a production direction (P), and to supply a gypsum slurry (6) to the facer (7) for covering it. In order to promote spread of the gypsum slurry (6) on the facer (7), it is proposed to vary over time in a width direction (W) transverse to the production direction (P) an emission position from which the gypsum slurry (6) is emitted to the facer (7) and to vary over time relative to the production direction (P) an emission direction in which the gypsum slurry (6) is emitted to the facer (7). Thus, among other things, a practical way of using gypsum slurry (6) of low fluidity (high viscosity) is provided. Both a method and a device for manufacturing a plasterboard are claimed.

Description

[0001] The invention relates to a method for manufacturing a plasterboard, wherein a facer of the plasterboard is supplied and made to move in a production direction, and wherein a gypsum slurry is supplied to the facer for covering the facer.

[0002] The invention also relates to a plasterboard manufacturing device comprising a conveyor configured to support a facer of the plasterboard and to move the facer in a production direction, and a gypsum slurry supplying arrangement configured to supply gypsum slurry to the facer when the facer is moved in the production direction.

[0003] The invention further relates to a plasterboard having a length and a width, comprising a gypsum core sandwiched between two facers.

[0004] The invention is applicable to the field of plasterboards, particularly the field of manufacturing a plasterboard. Generally speaking, manufacturing plasterboard involves supplying a first facer, depositing a gypsum slurry on it, and then placing a second facer on top of the gypsum slurry that is on the first facer. In this way, a plasterboard in the form of an entirety of two facers and a gypsum core sandwiched between the two facers is obtained. The facers are also referred to as cover sheets or as facing and backing, and may comprise any suitable material such as paper material for covering the gypsum core.

[0005] Usually, manufacturing a plasterboard is performed as a continuous process in which the first facer and the second facer are taken from respective rolls, and in which the first facer is supported on a conveyor. A gypsum slurry supplying arrangement is used to supply gypsum slurry to the first facer as the first facer is moved by means of the conveyor, at a position in the plasterboard manufacturing device where the gypsum slurry can be freely received by the first facer, which is a position upstream of a position in the plasterboard manufacturing device where the second facer is moved to encounter with the first facer and the gypsum slurry resting on the first facer.

[0006] Various embodiments of the gypsum slurry supplying arrangement are known in the art. For example, the gypsum slurry supplying arrangement may comprise a feeder and at least one boot coupled to and extending from the feeder. Usually the feeder is a mixer wherein a slurry comprising the solid and the liquid components, essentially calcined gypsum, water and additives, is first produced . The slurry is optionally foamed mechanically or chemically in the field of manufacturing a plasterboard, realizing spread of the gypsum slurry to a sufficient extent across a width of the plasterboard, i.e. in a direction perpendicular to a production direction in which the first facer advances during a plasterboard manufacturing process, poses a challenge. One solution to promote spread of the gypsum slurry on the first facer is found in using gypsum slurry of high fluidity (low viscosity). However, a notable drawback of this solution is that compared to using gypsum slurry of lower fluidity (higher viscosity), drying the plasterboard takes more time and requires more energy. Also, this solution blocks an option of manufacturing a plasterboard comprising high density gypsum. Another solution to promote spread of the gypsum slurry on the first facer is adapting the design of the plasterboard manufacturing device, such as by increasing the number of boots. However, a notable drawback of this solution is that complexity and costs of the plasterboard manufacturing device are increased as well.

[0007] US20178 / 0297233 A1 describes a solution to avoid the flushing of layer initially uniformly deposited.

[0008] US2010 / 0136259 A1 describes a process involving mixing water and calcium sulphate hemihydrate to form a slurry, adding an accelerator, and applying ultrasonic energy to the mixture to reduce setting time and density of the final product. The slurry passes through the conduit where ultrasonic energy is imparted as it forms the slurry stream on the paper.

[0009] JP2000296512 describes plasterboard process wherein a slurry outlet slides over the width direction of the production line.

[0010] CN109927152 describes a high speed production equipment for fiber gypsum board. The use of the lateral spring, in conjunction with vibration motor 1104, ensures that the discharge flexible pipes 1101 maintain vibration, allowing the gypsum slurry inside the pipes to flow out quickly. The vibration of the outlet does not change the emission direction

[0011] It is an object of the invention to provide yet another solution to promote spread of the gypsum slurry on the first facer. The solution is found in providing a method for manufacturing a plasterboard, wherein: a facer of the plasterboard is supplied and made to move in a production direction, a gypsum slurry having a slump diameter < 130 mm, preferably < 110 mm and more preferably <100 mm is supplied to the facer for covering the facer, and an emission position from which the gypsum slurry is emitted to the facer is varied over time in a width direction being a direction transverse to the production direction and an emission direction in which the gypsum slurry is emitted to the facer is varied over time relative to the production direction. The slump diameter being measured Schmidt ring of 60 mm width and 50 mm height. The slump diameter is a standard technique used widely in the gypsum plant. It consists in collecting a sample of slurry from the mixer, filling the Schmidt ring vertically on a flat and non-absorbent surface, leveling off the excess slurry. Then Lift the ring vertically in one motion to let the slurry spread and measure the slump diameter after the flow stops. If irregular, average two perpendicular measurements.

[0012] Likewise, the invention provides a plasterboard manufacturing device comprising: a conveyor configured to support a facer of the plasterboard and to move the facer in a production direction, a gypsum slurry supplying arrangement configured to supply gypsum slurry to the facer when the facer is moved in the production direction, and a gypsum spreading mechanism configured to vary over time in a width direction being a direction transverse to the production direction an emission position from which the slurry supplying arrangement emits the gypsum slurry to the facer and to vary over time relative to the production direction an emission direction in which the gypsum slurry supplying arrangement emits the gypsum slurry to the facer.

[0013] It follows from the foregoing definitions of the method and the device according to the invention that putting the invention in practice involves varying over time at least one of an emission position in the width direction and an emission direction relative to the production direction. In the practical case that the gypsum slurry is supplied to the facer from a mixer through at least one boot coupled to and extending from the feeder, two basic ways of realizing the variation of the emission position in the width direction and the emission direction relative to the production direction are available, namely, varying over time a direction relative to the boot at which the gypsum slurry is emitted from the boot through an outlet of the boot, and varying over time an orientation position relative to the production direction of at least an end portion of the boot including the outlet of the boot. In any case, the measure according to the invention promotes spread of the gypsum slurry over the width of the facer. This implies that the invention provides a practical possibility to make a plasterboard of increased density if so desired, and / or further helps to reduce the energy needed to manufacture the plasterboard. Also, the invention adds a range of possibilities to the field of manufacturing a plasterboard, following from the fact that the invention enables depositing the gypsum slurry on the facer in a track of which the position in the width direction varies along the length of the facer and thus along the length of the final plasterboard.

[0014] The invention covers any possible time pattern of varying the emission position in the width direction and varying the emission direction relative to the production direction, and also any possible way of controlling components of the plasterboard manufacturing device involved in setting the emission position and the emission direction. A feasible possibility which exists in the context of the invention is a possibility of continually varying the emission position in the width direction and continually varying the emission direction relative to the production direction, either in a continuous fashion or a stepwise fashion. The invention varies the emission position back and forth through a range of positions and varying the emission direction back and forth through a range of directions. The range of directions as mentioned may include the production direction and optionally has the production direction as a central direction. The range of directions spans at least 45°, more de 60°, more than 90° and more than 120°. It is further possible to set a speed at which the emission position is varied back and forth through the range of positions and / or a speed at which the emission direction is varied back and forth through the range of directions, wherein also a size of the range of positions is adjustable and / or a size of the range of directions is adjustable. The production direction is normally a non-variable and linear direction, in conformity with what is known in the art.

[0015] In one embodiment, emission position (Ep) and the emission direction (Ed) is not varied over time by ultrasonic energy.

[0016] As mentioned in the foregoing, assuming that the gypsum slurry is supplied to the facer from a feeder through at least one boot coupled to and extending from the mixer, one basic way of realizing the variation of the emission direction involves varying over time an orientation relative to the production direction of at least an end portion of the boot including the outlet of the boot. In this respect, the invention covers an embodiment of the plasterboard manufacturing device in which at least the end portion of the boot is movable relative to a position where the boot is coupled to the feeder, and the gypsum spreading mechanism comprises a movably arranged element coupled to the end portion of the boot. In that case, it is practical if the gypsum spreading mechanism comprises a driving system coupled to the movably arranged element and configured to impose motion on the movably arranged element. For example, the driving system comprises an arm which is coupled to the movably arranged element at one end and which is pivotable about a pivot axis at another end. In this way, the end portion of the boot can be made to follow a circularly curved path about the pivot axis of the arm. The movably arranged element may be a rod, for example, coupled at one end to the arm and at another end to the end portion of the boot.

[0017] The invention covers an advantageous option of providing the gypsum spreading mechanism in the form of components which are suitable to be added to an existing plasterboard manufacturing device, so that an existing plasterboard manufacturing device can easily be adapted to become a plasterboard manufacturing device according to the invention. The above-mentioned combination of a movably arranged element and a driving system is a practical example of such add-on components.

[0018] In conformity with what is known in the art, the plasterboard manufacturing device may comprise a foam injector for the purpose of injecting foam into the mixed gypsum slurry.

[0019] Numerous track patterns of gypsum slurry on the facer can be realized by means of the invention. For example, in the case that the emission position is varied back and forth through a range of positions and the emission direction is varied back and forth through a range of directions, a kind of zig-zag track of gypsum slurry is obtained. In the context of the invention, it is possible to have a number of such zig-zag tracks, crossing each other, wherein the respective zig-zag tracks may comprise gypsum of different density if so desired. Also, it is possible to combine one or more zig-zag tracks with one or more linear tracks, wherein the latter track or tracks can be deposited on the facer in a conventional way. This means that the invention covers an option of having an embodiment of the plasterboard manufacturing device in which the gypsum slurry supplying arrangement comprises at least one boot which is under the influence of the gypsum spreading mechanism and used to emit gypsum slurry from different width positions and / or in different directions at different points in time, and at least one further boot which is outside of the influence of the gypsum spreading mechanism and practically stationary relative to the mixer.

[0020] In view of the foregoing, the invention also provides a plasterboard having a length and a width, comprising a gypsum core sandwiched between two facers, wherein the gypsum core has at least one higher density zone where gypsum is present at increased density, and wherein, as seen in a longitudinal direction of the plasterboard, the higher density zone is located between longitudinal edges of the plasterboard, at a position which changes in a zig-zag fashion preferably on the entire width of the plasterboard. Thus, the higher density zone covers the entire width of the plasterboard between the longitudinal edges. Advantages of having a higher density zone in the plasterboard relate to acoustic properties of the plasterboard, and also to strength properties of the plasterboard.

[0021] In a comparable yet reversed fashion, the invention also provides a plasterboard having a length and a width, comprising a gypsum core sandwiched between two facers, wherein the gypsum core has at least one lower density zone where gypsum is present at decreased density, and wherein, as seen in a longitudinal direction of the plasterboard, the lower density zone is located between longitudinal edges of the plasterboard, at a position which changes in a zig-zag fashion, preferably on the entire width of the plasterboard.

[0022] The present invention will be further explained on the basis of the following description, wherein reference will be made to the figures, in which equal reference signs indicate equal or similar components, and in which: figure 1 diagrammatically shows components of a conventional plasterboard manufacturing device, including respective supplying arrangements of gypsum slurry and two facers; figure 2 diagrammatically shows components of a plasterboard manufacturing device according to the invention, including respective supplying arrangements of gypsum slurry and two facers; figure 3 diagrammatically shows three different positions of an arm which is part of a gypsum spreading mechanism of the plasterboard manufacturing device according to the invention; figure 4 illustrates an option of having two boots in the gypsum slurry supplying arrangement of the plasterboard manufacturing device according to the invention; figure 5 illustrates an option of having three boots in the gypsum slurry supplying arrangement of the plasterboard manufacturing device according to the invention; figure 6 illustrates how the gypsum slurry spreads over the same width of a first facer in a conventional case and a case according to the invention, respectively; and figure 7 illustrates the presence in a plasterboard of a higher density zone where gypsum is present at a higher density than in the remainder of the plasterboard.

[0023] The invention is in the field of manufacturing a plasterboard 1, and figure 1 diagrammatically shows components of a conventional plasterboard manufacturing device 2, including respective supplying arrangements 3, 4, 5 of gypsum slurry 6 and two facers 7, 8. One of the facers 7, 8 is referred to as first facer 7 and is supported by a conveyor 9 during a plasterboard manufacturing process, which conveyor 9 further serves to move the first facer 7 in a production direction P. The plasterboard manufacturing process involves depositing the gypsum slurry 6 on the moving first facer 7 and covering the entirety of the first facer 7 and the gypsum slurry 6 as present on top of the first facer 7 by means of the other facer 8, which is referred to as second facer 8. In the process, the second facer 8 is also moved in the production direction P.

[0024] The plasterboard manufacturing process is a continuous process in which large lengths of the facers 7, 8 are supplied and made to perform a similar movement in the production direction P. Both facers 7, 8 are wound off rolls 10, 11 while moving in the production direction P. The facers 7, 8 have a length and a width, and the movement in the production direction P of the facers 7, 8 is a movement in a longitudinal direction of the facers 7, 8. The facers 7, 8 may comprise any suitable material or combination of materials, such as paper material, non-woven facer or coated glass mats. The plasterboard 1 which is obtained as a final product of the plasterboard manufacturing process is an entirety of a gypsum core 12 sandwiched between the two facers 7, 8. The plasterboard manufacturing device 2 comprises a cutting arrangement (not shown) which serves to cut useful lengths of the plasterboard 1 from the large length at some point after the gypsum slurry 6 has been deposited on the first facer 7 and the second facer 8 has been put in place on the gypsum slurry 6. Practical examples of the width of the plasterboard 1 are 600 mm, 900 mm and 1,200 mm.

[0025] The gypsum slurry 6 is supplied to the moving first facer 7 by means of a gypsum slurry supplying arrangement 3 which comprises a a mixer 13 and at least one boot 14 coupled to and extending from the mixer13. The invention relates to the way in which the supply of the gypsum slurry 6 to the moving first facer 7 takes place. Generally speaking, in the conventional situation, the supply of the gypsum slurry 6 to the moving first facer 7 takes place in such a way that the gypsum slurry 6 ends up on the first facer 7 in a predefined fashion, practically without variation over time. Hence, at any time during the plasterboard manufacturing process, the way in which the gypsum slurry 6 is supplied to the moving first facer 7 looks the same. However, according to the invention, the way in which the gypsum slurry 6 is supplied to the moving first facer 7 is varied over time. In particular, an emission position E p from which the gypsum slurry 6 is supplied to the moving first facer 7 is varied over time in a width direction W being a direction transverse to the production direction P and an emission direction E d in which the gypsum slurry 6 is supplied to the moving first facer 7 is varied over time relative to the production direction P, as seen in a plane parallel to the first facer 7, which is normally a horizontally oriented plane.

[0026] Various ways of realizing the intended variation of the emission position E p and the emission direction E d exist. A practical way is now explained with reference to figures 2 and 3, which relate to a plasterboard manufacturing device 15 according to the invention and illustrate the use of a mechanism in the plasterboard manufacturing device 15 which is added relative to the conventional plasterboard manufacturing device 2, namely, a gypsum spreading mechanism 16. In the present example, the gypsum spreading mechanism 16 is configured to vary the emission position E p back and forth through a range of positions and the emission direction E d back and forth through a range of directions. A line representative of both ranges is depicted in figure 3 as a dash-and-dot line R. As can be seen in figure 3, the gypsum spreading mechanism 16 comprises an assembly of an arm 17 and a piston-cylinder device 18, arranged on the mixer 13. The arm 17 is arranged to perform a swinging movement in a plane parallel to the first facer 7, about a pivot axis A. The piston-cylinder device 18 engages on the arm 17 for the purpose of bringing about the swinging movement by extending and retracting. A practical way of controlling the piston-cylinder device 18 is bringing about repeating cycles of extension and retraction of the piston-cylinder device 18, so that the arm 17 is continually made to swing between one extreme position, which is a position in which the arm 17 points from the pivot axis A towards one longitudinal edge of the first facer 7 to another extreme position, which is a position in which the arm 17 points from the pivot axis A towards the other longitudinal edge of the first facer 7. Figure 3 shows from left to right a position of the arm 17 in which the arm 17 extends in the production direction P, an extreme position of the arm 17 to the one side and an extreme position of the arm 17 to the other side.

[0027] At a position which is at a distance from the pivot axis A, the arm 17 is coupled to an end portion of the boot 14 including the outlet 19 of the boot 14 through a rod 20 as shown in figure 2. For example, the rod 20 may be designed with a hook-shaped end portion in which the end portion of the boot 14 is held. As the arm 17 is moved under the influence of the extensions and retractions of the piston-cylinder device 18, the rod 20 is displaced and so is the end portion of the boot 14. In this way, the position of the end portion of the boot 14 is continually varied in the width direction W and the orientation of the end portion of the boot 14 is continually varied relative to the production direction P, which means that the emission position E p is continually varied in the width direction W and the emission direction E d is continually varied relative to the production direction P. For example, the boot 14 is made of flexible material, so that the end portion of the boot 14 can easily move along with the arm 17 and the rod 20.

[0028] Varying the emission position E p and the emission direction E d is a way to promote spread of the gypsum slurry 6 on the first facer 7. In the present case in which the emission position E p is continually varied back and forth through a range of positions and the emission direction E d is continually varied back and forth through a range of directions, the gypsum slurry 6 ends up on the first facer 7 more or less in a zig-zag track. In this respect, reference is made to figures 4 and 5, which illustrate a use of boots 14 of which an end portion is continually moved, as indicated by means of double-headed arrows, so that the emission position E p and the emission direction E d continually change. Figure 4 illustrates a use of two boots 14 in a mirrored arrangement relative to the production direction P, which results in two crossing zig-zag tracks of the gypsum slurry 6 on the first facer 7. Figure 5 illustrates a use of an additional centrally arranged boot 14, which results in three crossing zig-zag tracks of the gypsum slurry 6 on the first facer 7.

[0029] Figure 6 illustrates that compared to a conventional situation as shown at the top side of the figure, the gypsum slurry 6 reaches the longitudinal edges of the first facer 7 much faster, i.e. over a much shorter distance d in the production direction P, when the invention is applied, as shown at the bottom side of the figure. In a conventional situation with one boot 14, both the emission position E p and the emission direction E d are fixed, wherein the emission direction E d is the same as the production direction P, and wherein the gypsum slurry 6 needs to spread from a position on the first facer 7 which is central as seen in the width direction W towards the longitudinal edges of the first facer 7. In the situation of the invention, the emission position E p and the emission direction E d are varied so that the gypsum slurry 6 is not only emitted at a central width position and in the production direction P but also at positions closer towards the longitudinal edges of the first facer 7 and in respective directions towards the longitudinal edges of the first facer 7. Hence, in the situation of the invention, the gypsum slurry 6 is enabled to reach the longitudinal edges of the first facer 7 much faster, as gypsum slurry 6 is present over a larger portion of the width of the first facer 7 to start with. This effect is all the more notable in case the gypsum slurry 6 is a high density slurry which does not spread so easily as a low density slurry or actually does not spread at all. The high density of the slurry meaning the low fluidity of the slurry is measured by the slump diameter measured with the Schmidt ring. It has to be noticed that a slump of at least 160 mm is usually sought by the skilled person.

[0030] The fact is that the invention offers a practical possibility to manufacture a plasterboard 1 with a gypsum core 12 which is at least partially of high density. Advantages of such a plasterboard 1 are improved constructional strength and improved acoustic properties. It is noted that in the context of the invention, the density of the gypsum can be increased to values of 1,000 kg / m 2< and higher, even higher than 1,100 kg / m 2< , or even higher than 1,200 kg / m 2< .

[0031] Another advantage of the invention is to produce boards of a common density of 0.7-.9 using a ratio water / stucco which can be decreased. The amount of water to be evaporate being lower, energy is saved.

[0032] Figure 7 illustrates the presence in a plasterboard 1 of a higher density zone 21, i.e., a zone where gypsum is present at a higher density than in the remainder of the plasterboard 1. The plasterboard 1 with the higher density zone 21 can very well be manufactured by means of the process according the invention. In fact, figure 7 diagrammatically shows three sections through the plasterboard 1 taken along the width of the plasterboard 1, at different longitudinal positions. It can be seen that the position of the higher density zone 21 in the width direction W is dependent on the longitudinal position. In conformity with what has already been explained in the foregoing, it can particularly be so that the higher density zone 21 follows a zig-zag pattern as seen in a longitudinal direction of the plasterboard 1, namely, when an orientation of an end portion of the respective boot 14 has been reciprocated during the plasterboard manufacturing process. Due to the relatively high density of the gypsum, the gypsum slurry 6 emitted by the respective boot 14 has not spread, or has spread to a minimal extent only, over the first facer 7 after having been deposited on the first facer 7.

[0033] It is to be noted that a reversed embodiment of the plasterboard 1 is feasible as well, i.e., an embodiment including a lower density zone, i.e., a zone where gypsum is present at a lower density than in the remainder of the plasterboard 1, wherein the lower density zone follows a zig-zag pattern as seen in a longitudinal direction of the plasterboard 1.

[0034] It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims.

[0035] Notable aspects of the invention are summarized as follows. In the field of manufacturing a plasterboard 1, it is known to perform actions of providing a facer 7 of the plasterboard 1 and making the facer 7 move in a production direction P, and supplying a gypsum slurry 6 to the facer 7 for covering the facer 7. In order to promote spread of the gypsum slurry 6 on the facer 7, it is proposed to vary over time in a width direction W being a direction transverse to the production direction P an emission position E p from which the gypsum slurry 6 is emitted to the facer 7 and to vary over time relative to the production direction P an emission direction E d in which the gypsum slurry 6 is emitted to the facer 7. Among other things, a practical way of using gypsum slurry 6 of low fluidity (high viscosity) is provided, which involves a possibility of manufacturing a plasterboard 1 including high density gypsum, i.e., gypsum having a density of 1,000 kg / m 2< or higher.Reference list:

[0036] 1plasterboard 2manufacturing device 3supply arrangement of the slurry 4supply arrangement of the facer 5supply arrangement of the facer 6gypsum slurry 7facer 8facer 9conveyor 10facer roll 11facer roll 12gypsum core 13mixer 14boot 15manufacturing device 16spreading mechanism 17arm 18piston-cylinder device 19outlet 20rod 21higher density zone Pproduction direction E d emission direction E p emission position Rrange Wwidth direction ddistance for the slurry to reach the longitudinal edges of the future plasterboard

Claims

1. A method for manufacturing a plasterboard (1), wherein: - a facer (7) of the plasterboard (1) is provided and made to move in a production direction (P), - a gypsum slurry (6) having a slump diameter < 130 mm, preferably < 110 mm and more preferably <100 mm is supplied to the facer (7) for covering the facer (7), said slump diameter being measured Schmidt ring of 60 mm width and 50 mm height and - an emission position (Ep) from which the gypsum slurry (6) is emitted to the facer (7) is varied over time in a width direction (W) being a direction transverse to the production direction (P) and an emission direction (Ed) in which the gypsum slurry (6) is emitted to the facer (7) is varied over time relative to the production direction (P) wherein said emission position (Ep) is varied back and forth through a range of positions and the emission direction (Ed) is varied back and forth through a range of directions2. The method as claimed in claim 1, wherein the emission position (Ep) is continually varied in the width direction (W) and / or the emission direction (Ed) is continually varied relative to the production direction (P).

3. The method as claimed in claim 1 or 2, wherein the range of directions spans at least 45°, more de 60°, more than 90° and more than 120°.

4. The method as claimed in claim 3, wherein a speed at which the emission position (Ep) is varied back and forth through the range of positions is adjustable and / or a speed at which the emission direction (Ed) is varied back and forth through the range of directions is adjustable.

5. The method as claimed in claim 3 or 4, wherein a size of the range of positions is adjustable and / or a size of the range of directions is adjustable.

6. The method as claimed in any of claims 1-5, wherein: - the gypsum slurry (6) is emitted to the facer (7) from a mixer (13) through at least one boot (14) coupled to and extending from the mixer (13), and - a direction relative to the boot (14) at which the gypsum slurry (6) is emitted from the boot (14) through an outlet (19) of the boot (14) is varied over time and / or an orientation relative to the production direction (P) of at least an end portion of the boot (14) including the outlet (19) of the boot (14) is varied over time.

7. A plasterboard manufacturing device (15) comprising: - a conveyor (9) configured to support a facer (7) of the plasterboard (1) and to move the facer (7) in a production direction (P), - a gypsum slurry supplying arrangement (3) configured to supply gypsum slurry (6) to the facer (7) when the facer (7) is moved in the production direction (P), and - a gypsum spreading mechanism (16) configured to vary over time in a width direction (W) being a direction transverse to the production direction (P) an emission position (Ep) from which the slurry supplying arrangement (3) emits the gypsum slurry (6) to the facer (7) and to vary over time relative to the production direction (P) an emission direction (Ed) in which the gypsum slurry supplying arrangement (3) emits the gypsum slurry (6) to the facer (7) and wherein the gypsum spreading mechanism (16) is configured to vary the emission position (Ep) back and forth through a range of positions and / or to vary the emission direction (Ed) back and forth through a range of directions8. The plasterboard manufacturing device (15) as claimed in claim 7, wherein the gypsum spreading mechanism (16) is configured to continually vary the emission position (Ep) in the width direction (W) and / or to continually vary the emission direction (Ed) relative to the production direction (P).

9. The plasterboard manufacturing device (15) as claimed in claim 7 or 8,wherein the range of directions spans at least 45°, more de 60°, more than 90° and more than 120°.

10. The plasterboard manufacturing device (15) as claimed in any of claims 7-9, wherein: - the gypsum slurry supplying arrangement (3) comprises a mixer (13) and at least one boot (14) coupled to and extending from the mixer (13), and - the gypsum spreading mechanism (16) is configured to vary over time a direction relative to the boot (14) at which the gypsum slurry (6) is emitted from the boot (14) through an outlet (19) of the boot (14) and an orientation relative to the production direction (P) of at least an end portion of the boot (14) including the outlet (19) of the boot (14).

11. The plasterboard manufacturing device (15) as claimed in claim 10, wherein: - at least the end portion of the boot (14) is movable relative to a position where the boot (14) is coupled to the mixer (13), and - the gypsum spreading mechanism (16) comprises a movably arranged element (20) coupled to the end portion of the boot (14).

12. The plasterboard manufacturing device (15) as claimed in claim 11, wherein the gypsum spreading mechanism (16) comprises a driving system (17, 18) coupled to the movably arranged element (20) and configured to impose motion on the movably arranged element (20).

13. The plasterboard manufacturing device (15) as claimed in claim 12, wherein the driving system comprises an arm (17) which is coupled to the movably arranged element (20) at one end and which is pivotable about a pivot axis (A) at another end.

14. The plasterboard manufacturing device (15) as claimed in any of claims 10-13, wherein the gypsum slurry supplying arrangement (3) comprises at least one further boot (14) coupled to and extending from the mixer (13), which further boot (14) is outside of the influence of the gypsum spreading mechanism (3) and practically stationary relative to the mixer (13).

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