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Publication numberUS3916825 A
Publication typeGrant
Publication dateNov 4, 1975
Filing dateDec 17, 1973
Priority dateDec 15, 1972
Also published asDE2261598A1
Publication numberUS 3916825 A, US 3916825A, US-A-3916825, US3916825 A, US3916825A
InventorsSchnitzler Erwin, Schnitzler Ulrich
Original AssigneeSchnitzler Gmbh & Co E
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for coating fibers with binder to produce fiberboard
US 3916825 A
Abstract
An arbor having arms is rotated in a drum such that the ends of the arms sweep the inner wall of the drum and advance a mass of fibers or chips as a flowable fleece along the drum from an inlet to an outlet thereon. The inside wall of the drum is provided with at least one V-shaped baffle extending radially in from this wall and directed in the direction of displacement of the fleece so that it forms a dead-fluid region and a vortex street in the fleece. The binder is injected into the fleece at the dead-fluid region and mixes with the fibers in the vortex street. The baffle has relative to the arbor rotation axis a tangential length and a radial height both many times greater than the average fiber length.
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Description  (OCR text may contain errors)

United States Patent [191 Schnitzler et al.

[ 51 Nov. 4, 1975 1 APPARATUS FOR COATING FIBERS WITH BINDER TO PRODUCE FIBERBOARD [73] Assignee: E. Schnitzler GmbH & Co.,

Karlsruhe, Germany [22] Filed: Dec. 17, 1973 [21] Appl. No.: 425,135

[30] Foreign Application Priority Data Dec. 15, 1972 Germany 2261598 [52] US. Cl 118/303; 259/26 [51] Int. Cl. B05C 5/00 [58] Field of Search 118/303, 19, 418; 259/26, 259/25, 9; 117/109, 100 A 3,130,070 4/1964 Potters et a1 118/303 X 3,346,240 10/1967 Lavelle et a1. 259/26 3,841,262 10/1974 Groppenbacher et al. 118/19 Primary Examiner-John P. McIntosh Attorney, Agent, or Firm-Karl F. Ross; Herbert Dubno [57] ABSTRACT An arbor having arms is rotated in a drum such that the ends of the arms sweep the inner wall of the drum and advance a mass of fibers or chips as a flowable fleece along the drum from an inlet to an outlet thereon. The inside wall of the drum is provided with at least one V-shaped baffle extending radially in from this wall and directed in the direction of displacement of the fleece so that it forms a dead-fluid region and a vortex street in the fleece. The binder is injected into the fleece at the dead-fluid region and mixes with the fibers in the vortex street. The baffle has relative to the arbor rotation axis a tangential length and a radial height both many times greater than the average fiber length.

4 Claims, 6 Drawing Figures U.S. Patent Nov. 4, 1975 Sheet 1 of 2 3,916,825

BINDER (Z0 FIG. I

Sheet 2 of 2 US. Patent Nov. 4, 1975 APPARATUS FOR COATING FIBERS WITH BINDER TO. PRODUCE FIBERBOARD FIELD OF THE INVENTION BACKGROUND OF THE INVENTION The fibers, here including chips or other elongated pieces of material used in the production of construction chipboard or fiberboard (pressed board), are usually fed into a horizontal cylindrical drum at one end. This drum is rotated or an axially extending arbor in the center of the drum is rotated so that arms on this shaft displace the fibers axially toward an outlet. Binder in liquid form is injected into the drum usually through nozzles which open either radially or tangentially relative to the inner surface of the drum.

In order to prevent the fibers from being damaged, the rotationspeed is generally maintained high enough so that the mass of fibers forms a cylindrically hollow body or fleece lying against the inside of the drum, with the ends of the advancing or mixing arms serving to mix the binder with the fibers. Too slow a rotation speed causes the fibers to tumble and break. The so coated fibers are then formed into mats as discussed in the commonly assigned U.S. Pat. No. 3,655,098 of Ulrich Schnitzler. The mats are then pressed into rigid boards.

As a rule it is almost impossible to achieve a uniform binder coating over each fiber. Even though it is possible in such devices to mix the binder well with the fibers, many fibers are frequently left wholly or partially uncoated, which causes weaknesses in the finished board. Excessive mixing does little to remedy this situation, and often destroys the fibers.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved apparatus for the'coating of fibers.

Another object is the provision of an improved system which uniformly coats fibers for the production of fiberboard.

A further object is to provide a coating system which overcomes the above-given disadvantages.

SUMMARY OF THE INVENTION These objects are attained according to the present invention in a system wherein the interior of the coating drum is provided with at least one baffle which forms in the flowable fleece in the drum a dead-fluid region. A nozzle in this dead-fluid region injects binder into the flowable fleece being displaced from the inlet to the outlet of the drum by the arms of an arbor which sweep the inner wall of the drum. In this manner a vortex street is formed in back of the baffle, which according to this invention has a tangential length and a radial height which are both substantially greater than the average fiber length.

In accordance with further features of this invention the binder is injected at a rate (volume/unit time) which is between 45 and 55 percent the rate necessary to eliminate separation in back of the baffle. This principle is discussed at pages 9-28 and 9-29 of the Handbook ofFluid Dynamics edited by V. Streeter (McGraw 2 Hill: 1961). In thismanner a vortexstreet is maintained downstream in back of the baffle for best mixing of the binder and the fibers. v

, DESCRIPTION OFTl-IE DRAWING The above, and other objects, features, and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a longitudinal section partially in diagrammatic form through the apparatus according to this invention;

FIG. 2' is a cross section taken along line IlII of FIG. 1;

FIG. 3 is a view of the detail indicated by arrow III of FIG. 2;

FIG. 4 is a view in the direction of arrow IV of FIG.

FIG. 5 is a sectional view similar to FIG. 4 another form of this invention; and

FIG. 6 is a perspective view illustrating the function ing of the present invention. r

- SPECIFIC DESCRIPTION As shown in FIGS. 1 and 2 the apparatus comprises basically a cylindrical treatment drum'l formed with an inlet 2 in which fiber from a hopper 21' is fed and formed with an outlet 3 whence the coated fiber leaves. An arbor 4 extending along the axis A of the drum 1 has a plurality of axially staggered and diametrically opposed arms 5 whose ends sweep the interior of the drum as the arbor 4 is rotated about the axis A by a drive 6. This relative rotation, which could also be effected by rotating the drum concurrently with or instead of the arbor 4, forms all of the individual fibers F (FIG. 3) into a flowable fleece 9 lining the inside of the drum 1. Two injectors 7 axially between the arms 5 at the upstream end of the drum 1 are connected through a pipe 18 and a pump 19 to a source 20 of fluid binder.

FIGS. 3 and 4 show how each injector 7 is formed of a generally V-shaped baffle 10 having an apex directed indicating against the direction D of displacement of the arms t and of the fleece 9 and having front surfaces 10a extending radially to the axis A. Located between the flanks of this baffle 10 is a pair of nozzles 8 directed back in the direction D. The baffle has a length T measured tangentially to the drum 1 and a height R measured radially which are both multiples of the average length L of the fibers F. The relationship is maintained. Here R 6L, and T z 5L.

FIG. 6 shows the fleece 9 as if it were planar. Here it can be seen that a dead-fluid region 11 is formed in back of the baffle 10. A pair of vortices 16 are formed from the normally laminar flow 15 and are shed periodically to form a Karman vortex street 17 as discussed on page 9-6 of the above-cited Handbook of Fluid Dynam- An injector 13 as shown in FIG. 5 can be used in place of the injector 7 of FIG. 4. This arrangement is a single piece of metal of triangular section having a pair of sides 10' constituting the baffle and a bore l2terminating in a pair of nozzle orifices 8' opening in a back face 14 of the injector 13 in flow direction D. The sides have like but opposite inclinations, here 25, to the direction D.

EXAMPLE Fibers having a length between 1 mm and 5 mm, a width between 0.5 mm and 2 mm, and a thickness between 0.1 mm and 0.3 mm are used in fine fiberboard, the average length (L) being 3 mm. In coarser fiberboard the chips have a length between 3 mm and mm, a width between 2 mm and 8 mm, and a thickness between 0.4 mm and 0.5 mm, the average length being 10 mm. Thus the dimensions T and R of the baffle 10 and 13 lie between 30 mm and 35 mm. The flow speed in direction D is between m/sec and 35 m/sec.

We claim:

1. An apparatus for coating fibers with a binder, said apparatus comprising:

a drum having an axis and an axially spaced inlet and outlet;

an arbor extending axially in said drum and having axially spaced radially extending arms with ends adjacent the inner wall of said drum;

at least one baffle on said inner wall between axially spaced arms having a height in a radial direction and a length in a tangential direction, each many times greater than the average length of said fibers, said baffle having a pair of sides inclined to the direction of displacement of said fleece thereby and 4 terminating in a common apex pointing opposite this displacement direction;

means for relatively rotating said arbor and said drum with said ends of said arms sweeping said inner wall for displacing said fibers from said inlet to said outlet as a fluid fleece lying in a layer of limited thickness along said wall and forming a dead-fluid region in back of said baffle;

at least one nozzle on said inner wall of said drum in said dead fluid region directly in back of said baffle and between said sides; and

means for introducing binder into said drum through said nozzle, said fleece being advanced at a rate to form a vortex street in back of said dead-fluid region, said binder being injected at a volume rate per unit time equal to generally half the rate sufficient to eliminate said vortex street.

2. The apparatus defined in claim 1 wherein the radial height divided by the fiber length is greater than three and less than seven.

3. The apparatus defined in claim 1 wherein the tangential length of said baffle divided by the fiber length is greater than three and less than seven.

4. The apparatus defined in claim 1 wherein said drum is non-rotatable and said arbor and arms are totatable about said axis.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US149820 *Apr 14, 1874 wilkie
US254371 *Nov 3, 1881Feb 28, 1882 puffer
US3130070 *Aug 10, 1960Apr 21, 1964Potters RobertCoating method and apparatus
US3346240 *Jan 15, 1965Oct 10, 1967Ready T Pour IncMixing apparatus
US3841262 *Jun 7, 1972Oct 15, 1974Boehringer Mannheim GmbhApparatus for coating tablets
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3974307 *Feb 5, 1975Aug 10, 1976Bowen Michael EMethod for coating wood chips with resinous liquid
US4183676 *Dec 1, 1977Jan 15, 1980Draiswerke GmbhMethod of and apparatus for gluing wood chips
US4237814 *Mar 28, 1979Dec 9, 1980Laszlo BallaApparatus for the continuous production and coating of granulates in fluidized layer
US4402896 *Apr 26, 1982Sep 6, 1983The Celotex CorporationBlow line addition of thermosettable binder in fiberboard manufacture utilizing cooled nozzle
US4478896 *Nov 15, 1982Oct 23, 1984Macmillan, Bloedel LimitedApparatus for blending wood strands with a liquid resin
US4533436 *Aug 15, 1983Aug 6, 1985The Celotex CorporationApparatus for blow line addition of thermosettable binder in fiberboard manufacture including a cooling nozzle
US5057166 *Mar 20, 1989Oct 15, 1991Weyerhaeuser CorporationMethod of treating discontinuous fibers
US5064689 *Apr 9, 1990Nov 12, 1991Weyerhaeuser CompanyMethod of treating discontinuous fibers
US5071675 *Mar 20, 1989Dec 10, 1991Weyerhaeuser CompanyMethod of applying liquid sizing of alkyl ketene dimer in ethanol to cellulose fibers entrained in a gas stream
US5093058 *Mar 20, 1989Mar 3, 1992Medite CorporationApparatus and method of manufacturing synthetic boards
US5188785 *Mar 12, 1991Feb 23, 1993Medite CorporationApparatus and method of manufacturing synthetic boards including fire-retardant boards
US5200267 *Nov 13, 1991Apr 6, 1993Medite CorporationFire-retardant synthretic board product
US5432000 *Mar 22, 1991Jul 11, 1995Weyerhaeuser CompanyBinder coated discontinuous fibers with adhered particulate materials
US5498478 *Mar 17, 1994Mar 12, 1996Weyerhaeuser CompanyPolyethylene glycol as a binder material for fibers
US5516585 *May 25, 1993May 14, 1996Weyerhaeuser CompanyCoated fiber product with adhered super absorbent particles
US5582644 *Mar 2, 1994Dec 10, 1996Weyerhaeuser CompanyHopper blender system and method for coating fibers
US6270893Mar 7, 1994Aug 7, 2001Weyerhaeuser CompanyCoated fiber product with adhered super absorbent particles
US6551401Oct 19, 2000Apr 22, 2003Becker-Underwood, Inc.Machine for coloring landscaping material
US8663734 *Mar 17, 2008Mar 4, 2014Basf SeMethod for coating water-absorbing polymer particles
US20100104761 *Mar 17, 2008Apr 29, 2010Basf SeMethod for Coating Water-Absorbing Polymer Particles
US20100186470 *Apr 8, 2010Jul 29, 2010Agrium, Inc.Process and apparatus for coating a controlled release product in a rotating drum
US20120058267 *May 10, 2010Mar 8, 2012Basf SeCoating Process for Water-Absorbing Polymer Particles
Classifications
U.S. Classification118/303, 366/172.1
International ClassificationB01F15/02, B27N1/02, B01F7/02, B27N1/00, B01F7/04
Cooperative ClassificationB27N1/0245
European ClassificationB27N1/02D2B