System for producing an air laid web

• US 4,640,810 A
• Filed: 06/12/1984
• Issued: 02/03/1987
• Est. Priority Date: 06/12/1984
• Status: Expired due to Fees

• Current Assignee: SCAN Web of North America Incorporated
• Original Assignee: SCAN Web of North America Incorporated
• Inventors: Mosgaard, John, Nielson, Otto V., Poland, Clark L., Laursen, Henning
• Primary Examiner(s): Czaja, Donald
• Assistant Examiner(s): THEISEN, MARY LYNN F
• Application Number:
  US06/619,946
• Time in Patent Office: 966 Days
• Field of Search: 264/121, 264/517, 264/518, 425/80.1, 425/83.1
• US Class Current: 264/518
• CPC Class Codes: D04H 1/732 by fluid current, e.g. air-lay

Abstract

A system for forming an air laid web of fibers and/or particles on a moving foraminous carrier. Fibers and/or particles are blended, and while supported in an air stream, introduced into a distributor unit. The distributor unit includes a rotatable cylinder formed with classification apertures of a predetermined shape, number, and size as specifically related to the types of fibers and/or particles utilized. A rotatable shaft with radially extending wire-like members agitates the fibers and/or particles and throws them outwardly through the apertures. Downwardly directed air flow transports the refined fibers and/or particles so as to form a homogeneous, still further refined, web on the surface of the carier. A variety of adjustments and alternations can be made to the system and its components to control the composition and thickness of the end product, and to attain maximum capacity for any combination of fibers and/or particles.

Claims

1. A process for forming an air laid web of predetermined characteristics comprising the steps of:

(1) forming a stream of roughly graded material of first loose fibers and at least one of

(a) second loose fibers

(b) particles,

(2) directly and controllably introducing said stream of material into a mixing zone with air to produce an air-borne stream of said roughly graded material;

(3) forming a recirculating air-borne stream of said roughly graded material and said stream includes some clumps of fibers, called nits;

(4) causing said nits to be removed from said recirculating stream at at least two spaced locations;

(5) introducing said air-borne stream of step (2) into said recirculating stream of step (3);

(6) causing at least a portion of said recirculating stream of roughly graded material to rotate in one direction;

(7) causing an internal portion of said recirculating stream to rotate in an opposite direction to that of step (6);

(8) removing from the perimeter of said recirculating stream roughly graded material at the general location of said contrarotation, material of a predetermined size and shape to be a first finely graded material;

((9) causing said first finely graded material to become a directionalized air-borne stream;

(10) providing a translating zone of a portion of said first finely graded material where said translation is in a direction transverse to said directionalized air-borne stream of step (9); and

(10) providing a second fine grading of said material in said air-borne stream by arresting predetermined sizes and shapes of said first finely graded material in said translating zone to provide said web of predetermined characteristics as a second finely graded material web.

2. A process as set forth in claim 1 comprising the additional step of:

(11) controlling the rate of translation of said translating zone to thereby control the thickness of said web.

3. A process as set forth in claim 1 in which said rough graded loose fibers comprise at least first and second fibers and nits thereby comprising the additional step of:

(12) controlling the ratio of said first loose fibers and said second loose fibers and said particles in said stream of roughly graded material being introduced into said mixing zone in step (2).

4. A process as set forth in claim 1 comprising the additional step of:

(13) controlling the rate of flow of said air-borne stream of step (2) introduced into said recirculating stream of step (3).

5. A process as set forth in claim 1 comprising the additional step of:

(14) controlling the speed of rotation of said portion of said recirculating stream as called for in step (6).

6. A process as set forth in claim 1 comprising the additional step of:

(15) controlling the speed of contrarotation of said internal portion of said recirculating stream as called for in step (6).

7. A process as set forth in claim 1 comprising the additional step of:

(16) controlling the rate of deposition of said second finely graded material web.

8. A process as set forth in claim 1 comprising the additional step of:

(17) adjustably positioning the contrarotation of said internal portion of said recirculating stream as called for in step (7) relative to the rotation of said portion of said recirculating stream as called for in step (6).

9. A process as set forth in claim 1 wherein the particles are composed of a filler material.

10. A process as set forth in claim 1 wherein the particles are composed of a binder material.

11. A process as set forth in claim 1 wherein the particles are composed of a superabsorbent material.

12. Apparatus for forming an air laid web of predetermined characteristics material comprising:

supply means forming a stream of roughly graded material of first loose fibers and at least one of

(a) second loose fibers

(b) particles

and for mixing the roughly graded material with air to produce an air-borne stream thereof;

distributor means forming a recirculating air-borne stream of the roughly graded material adapted to receive the air-borne stream from said supply means, said distributor means including tumbler means causing at least a portion of the recirculating stream of roughly graded material to rotate in one direction and agitating means causing an internal portion of the recirculating stream to rotate in an opposite direction to that of said tumber means, said recirculating stream to have clumps of fibers, called nits;

said tumbler means being a first fine grading means having a plurality of classification apertures extending therethrough being of a predetermined shape, number, and size as specifically related to the types of the roughly graded material desired in said webs of predetermined characteristic introduced to said distributor means;

said agitating means adapted to cause flow through the classification apertures of a first finely graded material;

a plurality of nit removal conduits communicating with said distributor means at spaced locations with reference to said recirculating air-borne stream to remove nits from said stream;

air flow producing means causing the first finely graded material to become a directionalized air-borne stream; and

a foraminous carrier movable in a direction transverse to the directionalized air-borne stream being arranged to be a second fine grade means for arresting predetermined sizes and shapes of the first finely graded material resulting in a translating arrested web of material of predetermined characteristics.

13. Apparatus as set forth in claim 12 including variable speed drive means for moving said carrier at any one of a range of preselected speeds to thereby control the thickness of the web.

14. Apparatus as set forth in claim 12 wherein said supply means includes separate means of supply of at least first and second loose fibers, said supply means also includes valve means selectively operable to control the ratio of the first loose fibers and the second loose fibers and the particles being received in the air-borne stream.

15. Apparatus as set forth in claim 12 including means for controlling the rate of flow of the air-borne stream received within said distributor means.

16. Apparatus as set forth in claim 12 wherein said distributor means is positioned above the carrier and includes an air-borne stream receiving inlet connected to said supply means, and wherein said tumbler means includes a cylindrical drum adapted to receive the air-borne stream from said inlet, said drum being rotatable about its longitudinal axis, and wherein said agitating means includes a rotatable brush roll extending within said drum and having an axis generally parallel to the axis of said drum, a plurality of wire-like members extending radially outwardly from said brush roll adapted to rotationally agitate within said drum the roughly graded material in the air-borne stream and arranged to direct flow of the first finely graded material outwardly through the classification apertures.

17. Apparatus as set forth in claim 16 including first variable speed driver means for regulating the rotational speed of said drum to control the mass flow rate of the first finely graded material passing through the classification apertures.

18. Apparatus as set forth in claim 16 including second variable speed driver means for regulating the rotational speed of said brush roll to control the mass flow rate of the first finely graded material passing through the classification apertures.

19. Apparatus as set forth in claim 16 including first variable speed driver means for regulating the speed of rotation of said drum and second variable speed driver means for regulating the speed of rotation of said brush roll, to control the mass flow rate of fibers passing through the outlet apertures.

20. Apparatus as set forth in claim 19 wherein said drum and said brush roll rotate in opposite directions.

21. Apparatus as set forth in claim 16 wherein said drum has an interior surface, and wherein said distributor means includes support means rotatably mounting said brush roll and adjustment means for selectively adjusting the position of said shaft relative to said interior surface, and including second variable speed driver means for regulating the rotational speed of said brush roll to control the mass flow rate of the first finely graded material passing through the classification apertures.

22. Apparatus as set forth in claim 14 including means for controlling the rate of deposition of the second finely graded material web.

23. Apparatus as set forth in claim 14 wherein said air flow producing means includes suction means positioned adjacent said carrier for drawing air toward and through said carrier to aid in the deposition of the second finely graded material web on said carrier, and

an air flow conductor surrounding said distributor means for directing ambient air drawn by said suction means across said distributor means and through said carrier, said conductor extending between an open enlarged end and an open reduced end spaced therefrom, said reduced end positioned adjacent said carrier.

24. Apparatus as set forth in claim 12 wherein said reduced end extends across said carrier adjacent thereto and has an edge extending transverse to the carrier at a downstream zone at which said carrier moves beyond said reduced end, said edge being generally parallel to the surface of said carrier and spaced above said carrier to thereby define an exit opening for the material web to pass through;

and means for sealing the opening to confine air flow within said conductor.

25. Apparatus as set forth in claim 24 wherein said sealing means includes a seal roll rotatably mounted about an axis generally parallel to said edge and in proximate relationship and generally coextensive with the exit opening;

means pivotally mounting said seal roll for rolling engagement with the material web as it exits on said carrier from said downstream zone.

26. Apparatus as set forth in claim 25 including counterbalance weight means operatively associated with said seal roll, said counterbalance weight means being adjustable for selectively altering the pressure of said seal roll applied against the material web.

27. Apparatus as set forth in claim 16 including a frame and wherein said distributor means includes a pair of stationary end members on said frame at the opposite ends of said drum and having cavities in communication with the interior of said drum, said drum and said end members defining a receptacle for temporarily containing the air-borne stream therein;

and wherein said drum has an interior surface, support means on said frame mounting said rush roll for rotation about an axis generally parallel to the longitudinal axis of said drum; and

fastener means releasably fixing said means to said frame for selectively repositioning said brush roll relative to said interior surface while maintaining said brush roll parallel with the axis of said drum.

28. Apparatus as set forth in claim 16 wherein said distributor means includes;

a pair of said drums in side-by-side relationship rotatable about substantially parallel longitudinal axes;

a pair of stationary end members mounted at opposite ends of each of said drums and having cavities in communication with the interior of its associated said drum; and

means connecting the cavities of associated ones of said end members positioned in side-by-side relationship enabling continuous circuitous flow of the air-borne stream through said drums and the cavities of said end members.

29. Apparatus as set forth in claim 16 wherein said distributor means includes;

a pair of said drums in side-by-side relationship rotatable about substantially parallel longitudinal axes;

a pair of stationary end members mounted at opposite ends of each of said drums and having cavities in communication with the interior of its associated said drum;

means connecting the cavities of associated ones of said end members positioned in side-by-side relationship enabling continuous circuitous flow of the air-borne stream of the roughly graded material through said drums and the cavities of said end members; and

said nit removal conduit being arrayed for returning to said supply means the roughly graded material which has not advanced through the classification apertures.

30. Apparatus as set forth in claim 29 wherein said nit removal conduit includes:

a conduit extending between one of a pair of said end members and said supply means for permitting air flow therebetween; and

flow generating means operatively associated with said conduit for drawing air-borne roughly graded material from the cavity of each of said one of a pair of end members and returning the roughly graded material to said supply means.

38. Apparatus as set forth in claim 12 wherein said distributor means is positioned above the carrier and includes an air-borne stream receiving inlet connected to said supply means, and wherein said tumbler means includes a cylindrical drum adapted to receive the air-borne stream from said inlet, said drum being rotatable about its longitudinal axis, and wherein said agitating means includes a rotatable brush roll extending within said drum and having an axis generally parallel to the axis of said drum, a rotatable brush roll extending within said drum along an axis generally parallel to the axis of said drum, a plurality of wire-like members bent into a u-shape having a pair of generally parallel spaced apart legs and bight portion connecting said legs generally midway between the ends thereof;

a plurality of elongated mounting blocks, each of said mounting blocks having a generally flat surface on one side and a longitudinal recess on an opposite side extending substantially the length thereof and a plurality of holes extending therethrough between said flat surface and said recess, adjacent pairs of the holes adapted to receive therethrough said legs of said wire-like members, said bight portion being received within said recess such that said legs extend in a direction away from said flat surface; and

fastening means for mounting said blocks on the outer peripheral surface of said roll at substantially equally spaced circumferential locations such that the longitudinal axes of said blocks are substantially parallel to the longitudinal axis of said brush roll, said legs extending generally radially outwardly from said brush roll;

said wire-like members extending radially outwardly from said brush roll adapted to rotationally agitate the air-borne stream of roughly graded material within said drum and arranged to direct the flow of first finely graded material outwardly through the classification apertures.

31. Distributor means for forming an air laid web of material having predetermined characteristics and where said means is supplied roughly graded material on a translating foraminous carrier comprising:

a pair of spaced apart cup-shaped stationary end members axially aligned and having cavities facing towards each other;

a cylindrical drum rotatably mounted between said end members, coaxial therewith, and generally having the same diameter as said end memers, said drum and said end members together defining a receptacle for temporarily containing said roughly graded material therein in an air-borne stream, said drum having a plurality of classification apertures extending therethrough around the circumference thereof to act as a first fine grading means and being of a predetermined shape, number, and size as specifically related to the types of the material introduced to said receptacle to produce said web of predetermined characteristics;

inlet means operatively associated with one of said end members for introducing the air-borne stream of roughly graded material into said receptacle;

a rotatable brush roll mounted within said receptacle and having an axis generally parallel to the axis of said drum;

a plurality of wire-like members extending radially outwardly from said brush roll adapted to rotationally agitate the air-borne stream of roughly graded material within said receptacle upon rotation of said brush roll and arranged to direct the flow of said first finely graded material through the classification apertures; and

air flow producing means causing the first finely graded material to become a directionalized air-borne stream whereby predetermined shapes and sizes of the first finely graded material are arrested on said translating carrier resulting in a second finely graded material web of predetermined characteristics.

32. A distributor unit as set forth in claim 31 wherein the outlet apertures are rectangular shaped slots located at regularly spaced intervals both axially and circumferentially.

33. A distributor unit as set forth in claim 31 wherein the outlet apertures are round holes located at regularly spaced intervals both axially and circumferentially.

34. A distributor unit as set forth in claim 31 wherein the outlet apertures are rectangular slots located at regularly spaced intervals both axially and circumferentially and having an axial dimension substantially greater than a circumferential dimension.

35. A distributor unit as set forth in claim 31 wherein the outlet apertures are rectangular slots located at regularly spaced intervals around the circumference of said drum and staggered relative to one another in the axial direction and having an axial dimension substantially greater than a circumferential dimension.

36. A distributor unit as set forth in claim 31 wherein said drum and said brush roll are rotatable in opposite directions.

37. A distributor unit as set forth in claim 31 including a stationary frame and wherein said receptacle has an inner surface;

bearing means mounted on said frame for rotatably mounting said shaft at spaced apart locations; and

fastening means for releasably mounting said bearing means to said frame to selectively position said shaft at a plurality of positions relative to said inner surface and parallel to the axis of said drum.

39. A distributor unit for forming an air laid web of material having predetermined characteristics and where said means is supplied roughly graded material on a translating foraminous carrier comprising:

first and second pairs of spaced apart cup-shaped stationary end members, each of said pairs being axially aligned and each of said end members having a cavity facing towards the cavity of the other of said end members, said first and second pairs being disposed along parallel axes, one of said end members being an upstream end member and one of said end members being a downstream end member, said upstream end member of said first pair positioned adjacent said downstream end member of said second pair, said downstream end member of said first pair positioned adjacent said upstream end member of said second pair;

first and second cylindrical drums rotatably mounted, respectively, between said first and second pairs of end members, coaxial therewith, and generally having the same diameter as said end members, said drums and said end members defining, respectively, first and second receptacles for temporarily containing roughly graded material supported therein in an air-borne stream, each of said drums having a plurality of classification apertures extending therethrough around the circumference thereof being of a predetermined shape, number, and size as specifically related to the types of fibers and/or particles introduced to said respective receptacle, said receptacles enclosing upper regions and lower regions;

inlet means operatively associated with said upstream end member for each of said pairs thereof for introducing an air-borne stream of the roughly graded material into said respective receptacle for flow towards said downstream end member;

a rotatable brush roll mounted within each of said first and second receptacles and having an axis generally parallel to the axis of said respective drum;

a plurality of wire-like members extending radially outwardly from each of said brush rolls adapted to rotationally agitate the fibers within said first and second receptacles upon rotation of each said respective brush roll and arranged to direct the flow of first finely graded material through the classification apertures;

a first chute member connecting the upper regions within said first receptacle at said downstream end member of said first pair thereof with the lower regions within said second receptacle at said upstream end member of said second pair thereof;

a second chute member connecting the upper regions within said second receptacle at said downstream end member of said second pair thereof with the lower regions within said first receptacle at said upstream member of said first pair thereof; and

said first and second chute members enabling continuous circuitous flow of the air-borne stream of roughly graded material through said first and second receptacles.

40. A distributor unit as set forth in claim 39 including a nit removal means operatively associated with each of said downstream end members for removing from said first and second receptacles roughly graded material which has not advanced through the classification apertures.

41. In combination with a distributor unit as set forth in claim 40:

supply means for introducing into said inlet means an air-borne stream of roughly graded material and wherein said withdrawal means includes;

a conduit extending between each of said downstream end members and said supply means for permitting air flow therebetween; and

flow generating means operatively associated with said conduit for drawing roughly graded material from the cavity of each of said downstream end members and returning them to said supply means.

42. Blending apparatus for mixing roughly graded material of at least one of first and second types of loose fibers and particles into a homogeneous mixture in preparation for introducing the roughly graded material to air forming apparatus comprising:

a cylindrical container for confining a stream of air flowing between an inlet end and an outlet end;

a pair of inlet ducts communicating with said container for introducing the roughly graded material into said container, said inlet ducts being angularly disposed relative to said container so as to direct flow of the roughly graded material toward said outlet end;

a cone shaped container having major and minor ends and integrally mounted at its major end to said outlet end for receiving and homogeneously mixing the roughly graded material in the stream of air; and

blower means mounted to said minor end of said conical shaped container to receive therefrom for further mixing the air supported mixture of the roughly graded material and for conveying the air supported mixture of the roughly graded material to the air forming apparatus.

43. In apparatus for producing an air laid web of material having predetermined characteristics comprising:

a translating foraminous carrier;

a distributor unit positioned above the carrier having inlet means for receiving an air-borne stream of roughly graded material and outlet means for directing flow of the air-borne stream outwardly thereof;

means for redirecting portions of the air-borne stream which flow outwardly of said distributor unit to cause them to flow downwardly onto the surface of the carrier to form a homogeneous web of material;

an air flow conductor surrounding said distributor unit for directing ambient air across said distributor unit and through said carrier, said conductor extending between an open enlarged end and an open reduced end, said reduced end extending across said carrier adjacent thereto and having an edge extending transverse to said carrier at a downstream zone at which said carrier moves beyond said reduced end, said edge being generally parallel to the surface of said carrier and spaced above said carrier by a sufficient distance to thereby define an exit opening for the web of material to pass through;

the improvement comprising;

a cylindrical seal roll extending transverse to the direction of movement of said carrier and generally coextensive with and proximate to the exit opening for confining air flow within said conductor;

means rotatably mounting said seal roll about an axis generally parallel to said edge; and

journal means pivotally mounting said seal roll for movement transverse of said carrier; and

adjustable biasing means for controlling the pressure applied by said seal roll against the web of material formed on said carrier proximate to said edge.

44. Apparatus as set forth in claim 43 wherein said biasing means includes adjustable counterbalance means for selectively adjusting the pressure of said seal roll on the web of material.