STUCCO PAPER SCREEN ASSEMBLY

Abstract

A screen assembly includes a housing defining a material flow chamber and having an inlet end and an outlet end, and a stucco discharge opening being located in the chamber between the inlet end and the outlet end. An auger shaft is located in the housing for axial rotation and having at least one first helical flight arranged in a flight pattern oriented so that material engaging the first helical flight is conveyed from the inlet end to the outlet end. A screen surrounds the at least one first helical flight for common rotation and extends generally from the inlet end to the outlet end. At least one second helical flight is disposed on an exterior surface of the screen and is arranged in a flight pattern oriented so that material engaging the second helical flight is conveyed in a direction from the outlet end.

Claims

1. A screen assembly, comprising: a housing defining a material flow chamber and having an inlet end and an outlet end; a stucco discharge opening being located in said chamber between said inlet end and said outlet end; an auger shaft located in said housing for axial rotation and having at least one first helical flight arranged in a flight pattern oriented so that material engaging said first helical flight is conveyed from said inlet end to said outlet end; a screen surrounding said at least one first helical flight for common rotation and extending generally from said inlet end to said outlet end; and at least one second helical flight disposed on an exterior surface of said screen and arranged in a flight pattern oriented so that material engaging said second helical flight is conveyed in a direction to said stucco discharge opening.

2. The screen assembly of claim 1, wherein said second helical flight is constructed and arranged so that the material conveyed is directed toward said stucco discharge opening.

3. The screen assembly of claim 1, wherein said stucco discharge opening is located closer to said inlet than to said outlet.

4. The screen assembly of claim 1, wherein said screen is fabricated from perforated sheet material.

5. The screen assembly of claim 4, wherein said screen is provided in a plurality of semi-cylindrical segments individually attachable to said at least one first flight.

6. The screen assembly of claim 1, further including at least one air knife constructed and arranged for directing jets of compressed air to said screen for dislodging material caught on an interior surface of said screen.

7. The screen assembly of claim 6, further including a plurality of said at least one air knife disposed so that an entire length of said screen is exposed to said air jets.

8. The screen assembly of claim 7, wherein said plurality of air knives includes a first plurality of knives at a first height in operational relationship to said exterior surface of said screen, and a second plurality of knives at a second height in operational relationship to an outer edge of said at least one second flight.

9. The screen assembly of claim 6, further including a control unit and at least one valve connected to said at least one knife for emitting periodic pulses of compressed air through said at least one knife.

10. The screen assembly of claim 1, further including a power unit and a power transmission system connected to said power unit for rotating in common said shaft, said at least one first flight, said screen and said at least one second flight.

11. The screen assembly of claim 1, further including an oversize material discharge chute connected to said outlet end at one end and to a collection bin at an opposite end for collecting material held within said screen and conveyed by said at least one first flight to said outlet end.

12. The screen assembly of claim 11, further including a rotary valve in fluid communication with said chute.

13. A screen assembly, comprising: a housing defining a material flow chamber and having an inlet end and an outlet end; a stucco discharge opening being located in said chamber between said inlet end and said outlet end; an auger shaft located in said housing for axial rotation and having at least one first helical flight arranged in a flight pattern oriented so that material engaging said first helical flight is conveyed from said inlet end to said outlet end; a screen surrounding said at least one first helical flight for common rotation and extending generally from said inlet end to said outlet end, said screen is fabricated from perforated sheet material, said screen is provided in a plurality of semi-cylindrical segments individually attachable to said at least one first flight; at least one second helical flight disposed on an exterior surface of said screen and arranged in a flight pattern oriented so that material engaging said second helical flight is conveyed in a direction from said outlet end toward said stucco discharge opening; and at least one air knife constructed and arranged for directing compressed air to said screen for dislodging material caught on an interior surface of said screen.

14. The screen assembly of claim 13, further including a plurality of said at least one air knife disposed so that an entire length of said screen is exposed to said compressed air.

15. The screen assembly of claim 14, wherein said plurality of air knives includes a first plurality of knives at a first height in operational relationship to said exterior surface of said screen, and a second plurality of knives at a second height in operational relationship to an outer edge of said at least one second flight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic view of the present stucco paper screen assembly;

[0014] FIG. 2 is a fragmentary vertical cross-section of the present screen assembly;

[0015] FIG. 3 is a cross-section taken along the line 3-3 of FIG. 2 and in the direction generally indicated;

[0016] FIG. 4 is a cross-section taken along the line 4-4 of FIG. 2 and in the direction generally indicated;

[0017] FIG. 5 is a vertical section taken along the line 5-5 of FIG. 2 and in the direction generally indicated;

[0018] FIG. 6 is an enlarged fragmentary view of the present perforated screen with inner and outer flights;

[0019] FIG. 7 is a schematic vertical cross-section of the present screen assembly;

[0020] FIG. 8 is a fragmentary top perspective view of the present screen assembly with a section of the top cover removed; and

[0021] FIG. 9 is a fragmentary enlarged top perspective view of the screen assembly of FIG. 8.

DETAILED DESCRIPTION

[0022] Referring now to FIG. 1, the present screen assembly is generally designated 10, and includes a support frame 12, preferably made of steel or other structurally strong and durable material as known in the art. A hopper 14 is supported by the frame 12 and is constructed and arranged for receiving and retaining via gravity flow a supply of powdered stucco 16, obtained from recycling discarded wallboard panels, fragments of such panels, or other wallboard scraps created in the wallboard panel manufacturing process.

[0023] A main conveyor 18 featuring an axially rotating helical auger 20 conveys the comminuted or chopped up wallboard fragments from a source area (not shown) for separation of the desired ground stucco 16 from unwanted paper scraps 22. As is known in the art, the paper scraps 22 were originally used to form face or backing surfaces of the wallboard panels. Since the used paper 22 has less recyclable value than the stucco, and impedes the quality of the stucco, it needs to be separated for efficient reuse of the stucco. Stucco powder 16 falls from the conveyor 18 into the hopper 14 through a stucco discharge opening 24.

[0024] Referring now to FIGS. 1 and 2, the present paper removing apparatus, generally designated 30, is part of the screen assembly 10 and provides an improved system for more effectively separating the undesirable paper scraps 22 from the desired ground stucco 16. Included in the apparatus 30 is an elongate housing 32 defining a material flow chamber 34. The housing 32 has an inlet end 36 which is in fluid communication with the main conveyor 18, and preferably receives an end 38 or portion of the auger 20, which projects into the material flow chamber 34. Opposite the inlet end 36 of the housing 32 is an outlet end 40 which is in fluid communication with, and connected to a collected oversize material discharge chute 42 at a tube end 44. It is preferred that the stucco discharge opening 24 is located in the housing 32 between the inlet end 36 and the outlet end 40, and especially preferably closer to the inlet end.

[0025] The material discharge chute 42 is preferably oriented generally vertically. An opposite end 46 of the chute 42 is connected to a collection bin 48 for collecting material, namely the paper scraps 22, separated out from the discarded wallboard by the present paper separating apparatus 30. In the preferred embodiment, the collection bin 48 is provided with a protective cover 50, since the bin is typically located outside and exposed to the elements. In the preferred embodiment, to promote the vertically downward flow of paper scraps 22 through the collected oversize material discharge chute 42 to the collection bin 48, against ambient air currents, a rotary valve 52 is connected to, and in fluid communication with, the tube as is known in the art.

[0026] Referring now to FIGS. 1 and 2, and returning to the inlet end 36 of the housing 32, the auger 20 rotates axially and conveys fragmented wallboard panels into the material flow chamber 32 located within the housing. The present paper separating apparatus 30 features an auger shaft 54, which is actually an extension of the auger 20 that is located in the housing 32 for axial rotation. At one end 56, the shaft 54 is supported in a bearing 58, and at the opposite, driven end 60, the shaft is supported by another bearing 62 and is connected to a motor drive system 64. Included in the motor drive system 64, in the preferred embodiment, a motor 66 is operatively connected to a pulley and belt drive 68 which is connected to a gear-reducing transmission 70. The auger shaft 54 is connected to the gear-reducing transmission 70 as is known in the art, so that the motor 66 causes the shaft to rotate axially.

[0027] Referring now to FIGS. 2-7, also included on the shaft 54 is at least one first helical flight 72 arranged in a flight pattern, including flight radius and density per linear foot, and is oriented so that material engaging the flight is conveyed from the inlet end 36 to the outlet end 40 of the housing 32. It will be seen that, in the preferred embodiment, the first helical flight 72 has the same flight pattern as the auger 20, however other patterns are contemplated. An outer peripheral edge 74 of the first helical flight 72 provides a mounting reference point for a screen 76 which surrounds the first helical flight for common rotation. It is preferred that the screen 76 extends generally from the inlet end 36 to the outlet end 40 of the housing 32.

[0028] A common problem of prior paper separating devices, which typically employed screens made of woven wire filaments, is that paper scraps often became caught or lodged in the wire screen, thus inadvertently blinding the screen to the flow of powdered stucco. To prevent this problem, the present screen 76 is preferably a sheet or plate of steel or similar material in which a plurality of holes 78 (FIGS. 8 and 9) are formed by drilling, stamping or the like. After the screen 76 is perforated, it is preferably formed in an arc or semi-cylindrical shape to complement the outer peripheral edge 74 of the first helical flight 72. For facilitating maintenance of the apparatus 30, it is preferred that the screen 76 is provided in a plurality of arcuate, perforated segments 76a (FIG. 6), each separately attachable to the first helical flight 72.

[0029] Referring now to FIGS. 2, 4 and 6-9, another feature of the apparatus 30 is at least one second helical flight 80 disposed on an exterior surface 82 of the screen 76 and arranged in a flight pattern oriented so that material engaging the second helical flight is conveyed in a direction to the stucco discharge opening 24. In the preferred embodiment, the second helical flight 80 conveys collected material from the outlet end 40 to the stucco discharge opening 24. Thus, the preferred direction of material flow directed by the second helical flight 80 is opposite or reverse to that of the first helical flight 72, however, co-current direction is also contemplated, depending on the location of the stucco discharge opening. Where the first helical flight 72 directs material to the oversize material discharge chute 42 shown by the arrows A, the second helical flight 80 directs material to the stucco discharge opening 24, shown by the arrows B (FIG. 2). A radius of the second helical flight 80 is such that a peripheral edge 84 of the flight is enclosed within the chamber 34 of the housing 32 with sufficient clearance to accommodate rotation of the shaft 54, the first flight 72, the screen 76 and the second flight 80, all of which rotate as a unit under power generated by the motor 66. Also, referring again to FIG. 2, it will be noted that in the preferred embodiment, the second flight 80 does not extend the full length of the screen 76, but extends only from the outlet end 40 to a first edge of the stucco discharge opening 24. It is also contemplated that the first or inner flight 72 extends a longer distance than the second or outer flight 80.

[0030] The apparatus 30 is constructed and arranged so that mixed stucco 16, scrap paper 22 and chunks of discarded wallboard panels are conveyed by the conveyor 18 into the material flow chamber 34. Ideally, the screen holes 78 creating the perforations are dimensioned so that the paper scraps 22 are retained within the screen on the side of the first helical flight 72, which conveys the collected scraps to the outlet end 40 and ultimately, through the chute 42 to the collection bin 48.

[0031] At the same time, the stucco powder 16 is preferably of a relatively small particle size compared to the paper scraps 22, and has a granular or powdery consistency that readily passes through the screen holes 78 into the chamber 34, where the particles are collected by the second helical flight 80 and conveyed towards the inlet end 36, more specifically toward the stucco discharge opening 24.

[0032] Referring now to FIGS. 7-9, another feature of the present assembly 10, and more specifically the present paper separating apparatus 30, is at least one air knife, generally designated 90, which is constructed and arranged for directing jets of compressed air to the screen for dislodging material caught on an interior surface 92 of the screen. It is preferred that the jets of compressed air are directed at the exterior surface 82 of the screen 76 so that the compressed air blows any trapped paper scraps 22 towards the interior of the screen. As such, the action of the at least one air knife 90 is to dislodge the paper scraps 22 from the screen 76 and free them up for being conveyed by the first flights toward the chute 42, where they are conveyed to the collection bin 48.

[0033] In the preferred embodiment, there are a plurality of the air knives 90 disposed in spaced, linear arrangement so that an entire length of the screen 76 is exposed to compressed air jets. It is preferred that the screen 76 extends almost the full length of the housing 32, with appropriate clearance to promote free rotation of the combined screen and flights 72, 80.

[0034] As seen in FIGS. 7-9, each air knife 90 is connected by a piping system 94 to a source of compressed air 96. In the preferred embodiment, the source of air 96 is the same as used by the gypsum plant, however a dedicated compressor, or other source of compressed air is also contemplated. The air knives 90 are supplied compressed air from the existing factory air supply, optionally at 80-100 psi but variable as to specific plant location and provide jets of compressed air that are sufficiently strong pulses for dislodging paper scraps from the screen. Free ends 98 of the air knives 90 are preferably provided with nozzles 100 for directing the air more forcefully at a desired location as is known in the art. A regulator 101 is connected to the piping system 94 for adjusting the pressure of the compressed air applied to the air knives 90 as desired. In one embodiment, the regulated air pressure is 70 psi, but this is contemplated as varying to suit the application. As seen in FIG. 8, the nozzle 100 takes the form of a linearly arranged chute that generates a line of forced air along an axis that is parallel to the axis of rotation of the screen 76. Alternately, as seen in FIG. 7, the nozzles 100 are also contemplated as being fan-type, as is known in the art.

[0035] Referring to FIGS. 7 and 8, another feature of the present air knife 90 is that there is a first plurality of such knives 90a at a first height in operational relationship to the exterior surface 82 of the screen, and a second plurality of knives 90b at a second height in operational relationship to the outer or peripheral edge 84 of the at least one second flight 80. As such, the second plurality of knives 90b rotationally accommodates the movement of the combined screen 76 and flights 72, 80.

[0036] To conserve the compressed air, a control unit 102, preferably including a processor and associated circuitry that is connected to a distribution manifold 104. The manifold 104 is part of the piping system 94 and includes at least one valve 106, and under the control of the control unit 102, is provided to generate periodic pulses of compressed air from the knives 90a, 90b. The result is a periodic flushing or dislodgement of trapped scrap paper 22 from the screen 76 with a more efficient use of compressed air.

[0037] Referring again to FIG. 2, the housing 32 is preferably provided with a cover 108 to protect the recycled stucco, as well as the components of the assembly 30 from the elements. In addition, a user access port 110 is also provided in the cover 108.

[0038] While a particular embodiment of the present stucco paper screen assembly has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.