Device for the uniform distribution of slurries

Abstract

The invention relates to a conveyor line for the continuous production of drywall boards as well as a slurry distributing device which is used in this conveyor line. The distributing device is used for the uniform and low-speed flow distribution of slurries.

Claims

1. A slurry distributing device for preventing flushing effects in the production of gypsum plasterboards, the slurry distributing device comprising a process belt, wherein the slurry distributing device is equipped to be supplied with a gypsum slurry from at least one mixing device, to adapt a conveying speed of the gypsum slurry to a conveying device speed and to distribute the gypsum slurry uniformly over a desired width and then to deliver the distributed gypsum slurry onto a lower layer, the lower layer being the conveying device itself or a casing material lying on the conveying device, wherein the process belt actively transports the gypsum slurry in a delivery direction of the gypsum slurry and adapts the conveying speed of the gypsum slurry to the conveying device speed such that a relative speed of the gypsum slurry in the delivery direction in relation to a speed at which the lower layer is moving is approximately equal to zero, and wherein the gypsum slurry is a flowable gypsum slurry.

2. The slurry distributing device according to claim 1, wherein the slurry distributing device comprises, in addition to the process belt, a roller conveyor, wherein three or more rollers are disposed in parallel with one another in a common plane, the three or more rollers are rotatably mounted about their longitudinal axes and are disposed essentially perpendicular to the delivery direction of the gypsum slurry.

3. The slurry distributing device according to claim 2, wherein the three or more rollers are in direct contact with one another.

4. The slurry distributing device according to claim 2, wherein the three or more rollers are equipped to rotate in the delivery direction or alternately in the delivery direction and against the delivery direction.

5. The slurry distributing device according to claim 2, wherein the slurry distributing device also comprises at least one last roller in the delivery direction, which has a smaller diameter than the other rollers.

6. The slurry distributing device according to claim 5, wherein the at least one last roller is equipped to rotate against the delivery direction.

7. The slurry distributing device according to claim 5, wherein the last roller is disposed beneath the plane of the other rollers.

8. The slurry distributing device according to claim 5, wherein the last roller is pretensioned by means of a spring.

9. The slurry distributing device according to claim 2, wherein the process belt is disposed upstream of the roller conveyor.

10. The slurry distributing device according to claim 2, wherein the process belt and the roller conveyor have separate drive units.

11. A conveyor line for producing gypsum plasterboards, comprising a conveying device, at least one mixing device for mixing at least one gypsum slurry, and the slurry distributing device for preventing flushing effects in the production of gypsum plasterboards and comprising a process belt according to claim 1, wherein the slurry distributing device is disposed between a supply device for the at least one gypsum slurry and the delivery of the at least one gypsum slurry, and wherein the slurry distributing device is equipped to deliver the at least one gypsum slurry supplied from the at least one mixing device essentially uniformly onto a lower layer, wherein the lower layer is the conveying device itself or a casing material lying on the conveying device, wherein the slurry distributing device is equipped to actively transport the at least one gypsum slurry, and wherein the at least one gypsum slurry is a flowable gypsum slurry.

12. The conveyor line according to claim 11, wherein a discharge height of the flowable gypsum slurry from the slurry distributing device onto a surface of a lower layer is less than 5 cm.

13. The conveyor line according to claim 11, wherein the conveyor line comprises a plurality of the slurry distributing device, wherein the plurality of slurry distributing devices are disposed one after the other, by means of which identically or differently constituted slurries are delivered onto the lower layer.

14. The conveyor line according to claim 11, wherein a discharge height of the flowable gypsum slurry from the slurry distributing device onto a surface of a lower layer is less than 4 cm.

15. The conveyor line according to claim 11, wherein the lower layer is fed continuously with the flowable gypsum slurry.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

(1) FIG. 1: shows a plan view of a gypsum plasterboard, from which the cardboard has been removed, produced with a device from the prior art

(2) FIG. 2: shows a plan view of a gypsum plasterboard, from which the cardboard has been removed, produced with a slurry distributing device according to the invention

(3) FIG. 3: shows a diagrammatic representation of a detail of a conveyor line

(4) FIG. 4 shows a plan view of a roller conveyor

(5) FIG. 5A: shows a plan view of a belt plant with a distributing device with a conveyor belt

(6) FIG. 5B: shows a cross-sectional view of the belt plant from FIG. 5A

(7) FIG. 6A: shows a plan view of a distributing device, comprising a combination of a process belt and a roller conveyor

(8) FIG. 6B: shows a side view of the distributing device from FIG. 6A.

DETAILED DESCRIPTIONS OF THE DRAWINGS

(9) FIG. 1 shows a plan view of a gypsum plasterboard, there having been deposited on a coloured boundary layer 6 (represented shaded) a next layer of gypsum 7 by means of three hoses directly onto the boundary layer, the middle one of said hoses oscillating. The cardboard has been removed after completion of the gypsum plasterboard in order to allow the boundary layer to be seen. Straight-running regions 7 can be seen at the two longitudinal edges of the gypsum plasterboard and a meandering region 7 can be seen in the middle of the board. These regions 7 correspond to regions in which boundary layer 6 has been displaced by the flushing effect. Gypsum layer 6 lying beneath the latter is in direct contact with the cardboard (removed here). Regions 7 thus trace the regions in which the delivery hoses have delivered the gypsum slurry of the second layer onto the lower layer and washed away boundary layer 6.

(10) FIG. 2 shows a plan view of a gypsum plasterboard which has been produced with a slurry distributing device according to the invention. The surface cardboard has been removed, so that coloured boundary layer 6 (shaded), which was deposited directly onto the cardboard, can be seen. In contrast with the gypsum plasterboard that has been produced with a device according to the prior art (FIG. 1), no flushing effects can be seen here. The coloured boundary layer is present uniformly over the entire board surface.

(11) FIG. 3 shows diagrammatically a detail from conveyor line 1 according to the invention. Visible-side cardboard 2, onto which the gypsum mush or the slurry is deposited, is delivered onto a conveyor belt (not shown) via a deflection roller (not shown). Visible-side cardboard 2 is first coated with a boundary layer 6. For this purpose, a slurry 12 is delivered from boundary layer mixer 10 onto visible-side cardboard 2 and distributed by means of roller 14 over the width of the cardboard and smoothed out to the desired height.

(12) In parallel with this, rear-side cardboard 4 is coated with the aid of roller 16 with the same or a similar slurry 12 from boundary layer mixer 10.

(13) Slurry 20 for core layer 21 of the gypsum plasterboard is produced in a core layer mixer 18 and delivered via delivery hose 19 onto a slurry distributing device 22. In the present example, slurry distributing device 22 is a roller conveyor 222. Roller conveyor 222 comprises a plurality of rollers 224 of equal size and a discharge roller 226 at the end of roller conveyor 222 with a smaller diameter. Equal-sized rollers 224 of roller conveyor 222 are disposed in a plane and in this example have a diameter of approx. 60 mm, whilst the diameter of discharge roller 226 lies at approx. 25 mm. The rollers here have an average spacing of 0.008 mm from one another. The rollers are driven by two independently controlled drive units (not shown) and can rotate in different directions.

(14) The distributing device in the present case has a width of 1300 mm and is thus suitable for the production of gypsum plasterboards with a maximum width of 1250 mm. Narrower gypsum plasterboards can be produced by displacing edge plates (not shown), which limit the propagation width of gypsum slurry 20 on distributing device 22.

(15) Slurry 20 deposited onto roller conveyor 222 is first retarded by the active transport on rollers 224 and is then distributed in the width by backflows occurring in the gussets between individual rollers 224. Moreover, the conveying speed of slurry 20 is adapted to the conveying speed of the visible-face cardboard, i.e. of the conveying belt plant, so that slurry 20 has essentially the same speed as the lower layer in the conveying direction (arrow) when it is delivered onto the lower layerhere the visible-side cardboard, coated with boundary layer 6.

(16) At the end of roller conveyor 222, slurry 20 is delivered step-wise onto lower layer 6 via discharge roller 226 disposed lower down. The uppermost point of discharge roller 226 is disposed approx. 3 cm above the surface of the lower layer, here boundary layer 6, so that the drop height of slurry 20 from roller conveyor 222 onto lower layer 6 is only very small. Its impact upon striking the surface of boundary layer 6 is therefore also very small and does not trigger a flushing effect in the, in this case, boundary layer 6.

(17) After core layer 21 of slurry 20 has been deposited or delivered onto boundary layer 6 of visible-side cardboard 2, rear-side cardboard 4 with boundary layer 8 is applied onto core layer 21. The gypsum plasterboard strip is then allowed to set and is divided up into the desired board size (not shown). Drying of the boards then takes place, which removes the excess water from the gypsum plasterboards.

(18) FIG. 4 shows roller conveyor 222 once again in plan view.

(19) According to an alternative embodiment (not shown), a plurality of discharge rollers 226 can also be present. For example, four discharge rollers 226 can be provided. Discharge rollers 226 can then advantageously be disposed in an inclined plane, which continuously reduces the discharge height between roller conveyor 226 and the surface of lower layer 6, so that only a very small, i.e. less than 3 cm, specific discharge height is finally created.

(20) FIGS. 5A and 5B show in plan and in cross-section view an embodiment of the invention in which distributing device 22 is a process belt 230, more precisely a knife-edge belt. Slurry 20 of core layer 18 is delivered onto the belt via delivery hoses 19, which lie on process belt 230. Slurry 20 can be distributed actively, for example by means of a roller (not shown), over the entire width of process belt 230. If the viscosity of slurry 20 is sufficiently low, the slurry can also be distributed by simply flowing over the entire width of the belt. A vibrator can optionally be provided, which assists the flow. Process belt 230 reduces the speed of slurry 20 exiting from the delivery hoses to the speed at which the conveyor belt with visible-side cardboard 2 is running, so that there is virtually no longer any difference in speed in the conveying direction. The discharge height of slurry 20 to lower layer 6 is less than 3 cm. The discharge of slurry 20 onto the lower layer can take place by means of a stripper placed at an angle, e.g. between 40 and 50, or via the knife edge itself.

(21) The process belt can be cleaned free from adhering gypsum residues by means of a counter-rotating roller with a small diameter (20 to 45 mm diameter) disposed after the rear deflection roller (in the conveying direction), i.e. located beneath the knife edge (not shown).

(22) A distributing device 22, which comprises a combination of process belt 230 and roller conveyor 222, is shown in FIGS. 6A and 6B. In this case, slurry 20 is first delivered onto a process belt 230, where it is retarded and a first preliminary distribution of the slurry in the width takes place. Following the transfer onto roller conveyor 222, the process takes place as described in the text relating to FIG. 3.

(23) Process belt 230 is disposed in such a way that, when it circulates around the rear deflection roller (in the conveying direction), it runs directly adjacent to the first roller of roller conveyor 222. The gap between process belt 230 and the first roller of roller conveyor 222 is preferably less than 0.01 mm, so that both the belt and the first roller mutually clean one another free from adhering gypsum residues.

(24) Process belt 230 and roller conveyor 222 can be disposed in a plane and adjoining one another seamlessly. It is however also possible to dispose process belt 230 partially overlapping above of roller conveyor 222. Process belt 230 can then advantageously form an inclined plane. Slurry 20 is transferred in this case not onto the first roller of roller conveyor 222, but is deposited generally in the front part of roller conveyor 222.

(25) FIG. 6B shows a side view of an embodiment of the invention in which process belt 230 and roller conveyor 222 are disposed in a plane.

LIST OF REFERENCE NUMBERS

(26) 1 conveyor line according to the invention 2 visible-side cardboard 4 rear-side cardboard 6 lower boundary layer (lower layer) 7 region with visible flushing effect 8 upper boundary layer 10 boundary layer mixer 12 slurry for boundary layer 14 roller 16 roller 18 core layer mixer 19 delivery hose 20 slurry for core layer 21 core layer 22 slurry distributing device 222 roller conveyor 224 rollers of the roller conveyor 226 discharge roller of the roller conveyor 230 process belt