Apparatus and method for casting a stucco slurry layer of defined width onto a liner for production of gypsum plasterboards

Abstract

The invention concerns an apparatus for furnishing a liner with a layer of stucco slurry, comprising at least: a conveying device (24) for conveying a liner (7), said conveyor device defining a transport direction (31); a stucco slurry feeder device (26) for casting stucco slurry onto the liner (7); a stucco slurry distribution device (27) for distributing stucco slurry cast onto the liner (7); and at least one stripper device (28) for stripping stucco slurry from lateral portions of the liner. The invention further concerns a method for furnishing a liner with a layer of stucco slurry of defined width and a method for producing a gypsum plasterboard.

Claims

1. A method for furnishing a liner with a layer of stucco slurry of defined width, comprising: providing the liner and continuously conveying the liner along a transport direction; casting the layer of stucco slurry onto a surface of the liner; distributing the layer of stucco slurry across the liner; removing the layer of stucco slurry from lateral portions of the liner to obtain the liner with the layer of stucco slurry of defined width; scrubbing lateral portions of the liner after removing the layer of stucco slurry from the lateral portions of the liner; and reducing the thickness of the liner in the lateral portions during scrubbing of the lateral portions of the liner.

2. The method according to claim 1, further comprising: applying an adhesive to the lateral portions of the liner after removing the layer of stucco slurry from lateral portions of the liner.

3. The method according to claim 1, the method further comprising: casting a second layer of stucco slurry onto the layer of stucco slurry on the liner; providing a second liner and continuously conveying the second liner along a transport direction; casting a third layer of stucco slurry onto a surface of the second liner; distributing the third layer of stucco slurry across the second liner; removing the third layer of stucco slurry from lateral portions of the second liner to obtain the second liner with the third layer of stucco slurry of defined width; joint-depositing the third layer of stucco slurry onto the second layer of stucco slurry so as to join the liner and the second liner and produce a plate-like composite; and processing the plate-like composite to produce a gypsum plasterboard.

Description

(1) The invention will be explained in more detail with reference to the accompanying figures, wherein the figures show:

(2) FIG. 1: is a section through a gypsum plasterboard;

(3) FIG. 2: is a scheme of a part of a production line for producing gypsum plasterboards comprising the apparatus for furnishing a liner with a layer of stucco slurry according to the invention;

(4) FIG. 3: is a top view of the apparatus according to the invention;

(5) FIG. 4: is a view of a first embodiment of a stripper device as used according to the invention; and

(6) FIG. 5: is a perspective view of a second embodiment of a stripper device as used according to the invention.

(7) FIG. 1 shows a section through a gypsum plasterboard.

(8) Gypsum plasterboard 1 comprises a gypsum core 2. The gypsum core 2 has a layered structure comprising a first gypsum layer 3, a second gypsum layer 4, and a third gypsum layer 5. Gypsum core 2 is surrounded by a first liner 6 and a second liner 7. The first liner 6 covers the outer surface of the first gypsum layer 3 forming the visible side of gypsum plasterboard 1. The first liner 6 is folded around an outer edge of first gypsum layer 3 and is abutted on side surface portions 8 of first gypsum layer 3 and second gypsum layer 4 forming side surfaces of the gypsum plasterboard 1. First liner 6 is folded across an upper edge of second gypsum layer 4 and is fixed to an outer surface of second gypsum layer 4 with overlap portions 9. Between overlap portions 9 is arranged third gypsum layer 5. Lateral portions 10 of second liner 7 are adhered to overlap portions 9 of first liner 6 by an adhesive layer 11. The outer surface of the third gypsum layer 5 covered by second liner 7 forms the rear side of gypsum plasterboard 1.

(9) FIG. 2 schematically shows a production line for producing gypsum plasterboards. A first liner 6 is continuously conveyed on a conveyor belt 13. Conveyor belt 13 has a transport direction indicated by arrow 14. First liner 6 is positioned flat on conveyor belt 13 by roller 15. A first slurry is prepared in first mixer 16 and is transported through distribution line 17 to first stucco slurry feeder 18 to be cast onto first liner 6. The first slurry is distributed across the surface of first liner 6 by a roller 19 to obtain a layer of first stucco slurry. Lateral portions of the first liner 6 are then folded upwardly by folding device 20. A second stucco slurry is prepared in second mixer 21 and transported to second slurry feeder 22 through distribution line 23. The second slurry is cast onto the first stucco slurry layer by second stucco slurry feeder device 22.

(10) A second liner 7 is continuously conveyed via a series of rollers 24. A third stucco slurry from first mixer 16 is transported through distribution line 25 to third stucco slurry feeder 26 and is cast onto to second liner 7. The first stucco slurry and the third stucco slurry can be the same. However, they also can be different, for example concerning the additives contained in the slurry. The third stucco slurry is distributed across the surface of second liner 7 by roller 27. Third stucco slurry spilled onto lateral portions of second liner 7 is removed by stripping device 28. Lateral portions of second liner 7 are then brushed by grinder 29 wherein the thickness of second liner 7 is reduced in the lateral portions. An adhesive is applied to lateral portions of the second liner 7 by adhesive feeder 30.

(11) The second liner 7 is diverted by roller 36 and its slurry coated side is contacted with the second stucco slurry layer placed on first liner 6 thereby forming a layered core stucco layer sandwiched between the first liner 6 and the second liner 7.

(12) The layered formation of first liner 6, first, second, and third stucco slurry layer and second liner 26 is then formed into a plate-like composite by a forming device (not shown).

(13) FIG. 3 shows a top view of an apparatus for furnishing a liner with a layer of stucco slurry according to the invention.

(14) A liner 7 is transported via a series of rollers (not shown) in a transport direction 31. Third gypsum slurry 32 is cast onto liner 7 by stucco slurry feeder device 26 connected to first mixer 16 (not shown). Roller 27 distributes stucco slurry 32 across liner 7 such that central portion 33 of liner 7 is covered by a layer of stucco slurry. The width of roller 27 corresponds approximately to the width of central portion 33 of liner 7. Excess stucco slurry is spilled around terminal ends of roller 17 onto lateral portions 34 of liner 7.

(15) By action of stripper devices 28 stucco slurry 32 present in lateral portion 34 of liner 7 is redirected towards central portion of liner 7. Stripper device 28 is tilted such that its side edge which is closer to the middle of the liner is arranged further downstream than its outer side edge. The stripper device 28 comprises a deflection side 35 for redirecting stucco slurry 32 spilled onto lateral portions 34 of liner 7 towards the central portion 33. A tilt angle 39 is enclosed between deflection side 35 and a plane 40 transversal to the transport direction 31. In the embodiment shown in FIG. 3 an angle of 135 is enclosed between deflection side 35 and plane 40.

(16) A round grinding belt 29 for abrading material of liner 7 to thereby reduce the thickness of liner 7 in lateral portions 34 is provided downstream of stripper device 28.

(17) An adhesive feeder comprising a nozzle 36 for ejecting adhesive onto lateral portions 34 of liner 7 and a blade 37 for distributing the adhesive across lateral portion 34 of liner 7 to obtain a trace 38 of adhesive are provided downstream of grinding belt 29.

(18) FIGS. 4a-c schematically show a first embodiment of a stripper device 28 as used according to the invention for removing stucco slurry from lateral portions of a liner. The embodiment shown in FIG. 4 has rectangularly arranged outer surfaces.

(19) FIG. 4a shows the front side of stripper device 28 corresponding to deflection side 35 of the stripper device. Deflection side 35 is formed as a rectangular flat plane. An attachment device 42 is provided for attaching the stripper device to the conveying line (not shown).

(20) FIG. 4b shows a side view of the stripper device. At the lower end of deflection side 35 is provided a lower edge 41. Lower edge 41 has a rectangular shape in the embodiment shown. However, it is also possible to provide a rounded shape to lower edge 41. Lower edge 41 is gliding on the liner (not shown). Stucco slurry provided on the liner is retained by deflection side 35 and is removed from lateral portions of the liner.

(21) FIG. 4c shows a top view of stripper device 28. Deflection side 35 is facing against the transport direction. The stripper device has an overall cuboid form with surfaces arranged to each other with rectangular angels.

(22) FIG. 5 shows a perspective view of a second embodiment of the stripper device 28 as used according to the invention. The stripper device 28 is attached to an attachment device 42, fixing the stripper device 28 to the production line. Stripper device 28 comprises an upper body 43 having a cuboid form. The upper body 43 is continued to a lower body 44. In the lower body the thickness of the stripping device is gradually reduced to a scraper lip 45 positioned at the lower end of the stripping device at a side opposite to attachment device 42. During operation of the production line according to the invention scraper lip 45 contacts the surface of the liner to push away stucco slurry present in lateral portions of the liner.

REFERENCE NUMERALS

(23) 1 Gypsum plasterboard 2 Gypsum core 3 First gypsum layer 4 Second gypsum layer 5 Third gypsum layer 6 First liner 7 Second liner 8 Edge portion 9 Overlap portion of first liner 10 Lateral portion of second liner 11 Adhesive layer 12 First slurry mixer 13 Conveyor belt 14 Transport direction 15 Roller 16 First mixer 17 Distribution line 18 First stucco slurry feeder 19 Roller 20 Feeding device 21 Second mixer 22 Second stucco slurry feeder 23 Distribution line 24 Roller 25 Distribution line 26 Third stucco slurry feeder 27 Roller 28 Stripper device 29 Grinder 30 Adhesive feeder 31 Transport direction 32 First stucco slurry 33 Central portion 34 Lateral portion 35 Deflection side 36 Roller 37 Blade 38 Adhesive trace 39 Tilt angle 40 Plane 41 Lower edge 42 Attachment device 43 Upper body 44 Lower body 45 Scraper lip