US3261468A - Screen cleaning device - Google Patents

Screen cleaning device Download PDF

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Publication number
US3261468A
US3261468A US281297A US28129763A US3261468A US 3261468 A US3261468 A US 3261468A US 281297 A US281297 A US 281297A US 28129763 A US28129763 A US 28129763A US 3261468 A US3261468 A US 3261468A
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Prior art keywords
foil
screen
cleaning device
face
adjacent
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Expired - Lifetime
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US281297A
Inventor
George M Dick
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Bird Machine Co Inc
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Bird Machine Co Inc
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Publication date
Priority to DENDAT1250726D priority Critical patent/DE1250726B/en
Application filed by Bird Machine Co Inc filed Critical Bird Machine Co Inc
Priority to US281297A priority patent/US3261468A/en
Priority to FI641032A priority patent/FI42789C/en
Priority to GB20093/64A priority patent/GB1032969A/en
Priority to GB33312/65A priority patent/GB1032970A/en
Priority to SE5956/64A priority patent/SE313986B/xx
Application granted granted Critical
Publication of US3261468A publication Critical patent/US3261468A/en
Priority to SE00988/68A priority patent/SE339613B/xx
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D21D5/023—Stationary screen-drums
    • D21D5/026—Stationary screen-drums with rotating cleaning foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/114—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for inward flow filtration
    • B01D29/115—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for inward flow filtration open-ended, the arrival of the mixture to be filtered and the discharge of the concentrated mixture are situated on both opposite sides of the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/117—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration
    • B01D29/118—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration open-ended
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/13—Supported filter elements
    • B01D29/15—Supported filter elements arranged for inward flow filtration
    • B01D29/17—Supported filter elements arranged for inward flow filtration open-ended the arrival of the mixture to be filtered and the discharge of the concentrated mixture are situated on both opposite sides of the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/13—Supported filter elements
    • B01D29/23—Supported filter elements arranged for outward flow filtration
    • B01D29/25—Supported filter elements arranged for outward flow filtration open-ended the arrival of the mixture to be filtered and the discharge of the concentrated mixture are situated on both opposite sides of the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/50—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition
    • B01D29/52—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition in parallel connection
    • B01D29/54—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition in parallel connection arranged concentrically or coaxially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/76—Handling the filter cake in the filter for purposes other than for regenerating
    • B01D29/86—Retarding cake deposition on the filter during the filtration period, e.g. using stirrers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D21D5/06—Rotary screen-drums
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/28—Position of the filtering element
    • B01D2201/287—Filtering elements with a vertical or inclined rotation or symmetry axis

Definitions

  • This invention relates to fibrous pulp screening apparatus and more particularly to an improved screen cleaning device for such processing apparatus.
  • Another object of the present invention is to provide an improved screen cleaning device which provides uniform pulsing on the adjacent screen along the length of a cleaning foil.
  • Yet another object of the present invention is to provide an improved screen cleaning device which provides improved direction of undesirable material in the stock toward the reject trap.
  • Still another object of the present invention is to provide an improved screen cleaning device which provides improved direction of undesirable material in the stock from the adjacent screen.
  • a screening device for fibrous pulp having a generally cylindrical screen and means for conducting a stream of pulp across a cylindrical face of said screen, an improved screen cleaning device comprising at least one elongated foil supported adjacent one end only thereof for movement in a circular path about the axis of the screen and across a face thereof, the clearance between the foil and the adjacent screen face varying from the supported end to the free end of the foil at rest, the extent of said variation at rest being substantially equal to the extent of bending of said foil under the influence of centrifugal force under operating conditions, and means for rotating said foil about said axis to clean said screen.
  • the objects of the invention are-achieved in another embodiment of the invention by providing a screen cleaning device in which at least one elongated foil is provided which is supported adjacent one end only thereof for movement in a circular path about the axis of the screen 3,261,468 Patented July 19, 1966 and across a face thereof, the foil being hollow and filled with air or other gas so as to have minimum mass and consequently to be subject to so little stress under the influence of centrifugal force during operation that no appreciable bending occurs; consequently, the hollow foil is mounted so that the clearance between the foil and screen face is uniform along the length of the foil at rest and remains so during operation.
  • FIG. 1 is a side elevational view partially in vertical section of a fibrous pulp screening apparatus of the general type shown in US. Patent No. 2,975,899 incorporating the improved screen cleaning device of the present invention
  • FIG. 2 is an enlarged plan view of the spider taken along the line 2-2 of FIG. 1 in the direction of the arrows;
  • FIG. 3 is a side elevational view partly broken away along the line 33 of FIG. 2 in the direction of the arrows showing a foil mounting lug for mounting an outer foil;
  • FIG. 4 is a view partly in vertical section along the line 4-4 of FIG. 3 in the direction of the arrows;
  • FIG. 5 is a view along the line 55 of FIG. 2 in the direction of the arrows;
  • FIG. 6 is a view partly in vertical section along the line 6-6 of FIG. 5 in the direction of the arrows;
  • FIG. 7 is a diagrammatic side elevational view of an inclined straight foil disposed adjacent the inner surface of a screen
  • FIG. 8 is a view similar to FIG. 7 of an inclined straight foil disposed adjacent the outer surface of a screen
  • FIG. 9 is a view similar to FIG. 7 of a variant in which the screen has a conical face and the foil lies in a true cylindrical surface when at rest;
  • FIG. 10 is a side elevational view of a helical foil for improved direction of undesirable material in the stock toward the reject trap;
  • FIG. 11 is a fragmentary view in horizontal section of an outer foil of unique cross-sectional configuration for directing undesirable material in the stock away from the screen;
  • FIG. 12 is a fragmentary view in horizontal section of an inner foil of unique cross-sectional configuration for directing undesirable material in the stock away from the screen;
  • FIG. 13 is a fragmentary view corresponding to FIG. 1 showing another embodiment of the invention.
  • FIG. 14 is a view in section taken along line 14-14 of FIG. 13.
  • FIG. 1 a paper pulp screening apparatus of the general type shown in US. Patent No. 2,975,899 is indicated by the reference numeral 10.
  • This paper pulp screening apparatus 10 comprises an in ner cylindrical screen 12 and outer cylindrical screen 14-, concentrically spaced from each other.
  • Inlet means 16 introduces a stream of liquid suspension under pressure into the top of the annular chamber or fiber passageway 18 defined by the inner screen 12 and outer screen 14.
  • a screen cleaning device such as a pair of inner vanes or foils 20 (FIG. 6) and a pair of outer foils 22 of the present invention are mounted on rotatable foil mounting means, such as a rotatable spider 24, for rotational movement adjacent the inner screen 12 and outer screen 14.
  • Drive means 26 for rotating a spider shaft 28, the spider 24, and the inner foils 20 and outer foils 22 comprises the V-belt pulley 30, connected by conventional means, such as belts 32, to a conventional source of power, such as an electric motor (not shown).
  • outer foils 22 are disposed adjacent the inner face of the outer screen 14 and that the inner foils 20 are disposed adjacent the outer face of the inner screen 12. All of the foils, upon rotation of spider 24, are mounted for movement in a circular path about the axis of the screens and across their faces.
  • the liquid suspension passes through the inner screen 12 and outer screen 14 into an inner annular chamber 34 and outer annular chamber 36, respectively, and thence into delivery means 38 for withdrawing screened liquid suspension from the inner annular chamber 34 and outer annular chamber 36.
  • Reject means 40 accepts rejected material from the fiber passageway 18.
  • the spider 24 has an inner circular mounting plate 42 connected by bolts 44 (FIG. 2) to an outer ring 46 having a plurality of, for example, two inner foil mounting lugs 48 (FIGS. 2, 5, and 6), and two outer foil mounting lugs 50 (FIGS. 2-6) depending therefrom.
  • an outer foil 22 is mounted at an angle B with respect to the axis of rotation of the spider 24 by means of shims 52 disposed between the outer foil 22 and outer foil mounting lug 50.
  • Bolts 54 and a key 56 on the outer foil 22 projecting into a keyway 58 in the outer foil mounting lug 50 secure the outer foil 22 at the desired angle B with respect to the axis of rotation.
  • the outer foil 22 may be also mounted at an angle B with respect to the axis of rotation without the necessity of using shims by appropriate tapering of the contact surfaces 60, 62 of the lug or foil respectively.
  • the clearance between each foil and the adjacent screen surface, when the foil is at rest is not uniform but varies along the length of the foil, increasing toward the free end of the foil. This variation is substantially equal to the extent of distortion or bending of the foil under the influence of centrifugal force under operating conditions, i.e., when the foils are swept across the faces of the screens by rotation of spider 24 to clean the screens of any accumulated pulp.
  • faces 662 and 660 respectively arranged at an angle with respect to the screen surfaces may be provided on outer foil 220 and inner foil 200.
  • an inner foil 20 may be similarly mounted at an angle B with respect to the axis of rotation of the spider 24 by the use of shims 552, bolts 542, key 562, and keyway 582.
  • the variation in clearance decreases toward the free end of each foil.
  • angles B and B may be calculated readily in any particular case by computing the centrifugal force under intended operating conditions and the deflection caused by the force for given materials of construction and dimensions.
  • the centrifugal force F in pounds is computed as follows:
  • the deflection S in inches of the free end of the foil is computed as follows:
  • the angle B or B is a function of S and L.
  • an inclined foil such as an inner foil 20 (FIG. 10) may he formed as a portion of a helix having a steep pitch angle a with respect to the axis of rotation.
  • outer foil 250 is hollow, being made from sheet metal, e.g., austenitic stainless steel, and hermetically sealed so that it contains only air or other gas. The low mass of foil 250 so reduces stress on the foil due to centrifugal force during operation that no appreciable bending of the foil occurs and the clearance between the foil and the screen remains substantially uniform both when the foil is at rest and when it is in operation.
  • an improved screen cleaning device which eliminates the accumulation of deleterious fibrous bundles and strings in the fiber passageway adjacent the screen of a fibrous pulp screening apparatus, prevents jamming of the screen cleaning device against the screen, prevents clogging of the screen, and permits the operation of the fibrous pulp screening apparatus by a low horsepower drive means.
  • the improved screen cleaning device provides uniform pulsing on the adjacent screen.
  • such improved screen cleaning device provides improved direction of undesirable material in the stock both toward the reject trap and away from the screen.
  • an improved screen cleaning device comprising at least one elongated foil, means for supporting said foil adjacent one end only for movement in a circular path about the axis of the screen and across a face thereof and spaced from said face, the clearance between the foil and the adjacent screen face varying from the supported end to the free end of the foil at rest, the extent of said variation at rest being substantially equal to the extent of bending of said foil under the influence of centrifugal force under operating conditions, so that under operating conditions, the clearance between said foil and said screen is substantially uniform, and: means for rotating said foil about said axis to clean said screen.
  • a screening device as claimed in claim 1 in which said foil is of helical configuration.
  • a screening device as claimed in claim 2 in which said foil is mounted for movement across the inner face of said screen and the clearance increases toward the free end.
  • a screening device as claimed in claim 2 in which said foil is mounted for movement across the outer face of said screen and the clearance decreases toward the free end.
  • a screening device as claimed in claim 1 in which said screen at least in part has a slightly conical surface.
  • an improved screen cleaning device comprising at least one elongated foil supportedadjacent one end only for movement in a circular path about the axis of the screen and across a face thereof, the clearance between the foil and the adjacent screen face being uniform along the length of the foil at rest, said foil being hollow and hermetically sealed and containing essentially only a gaseous fluid in its interior to minimize its mass and the extent of bending of said foil under the influence of centrifugal force under operating conditions, and means for rotating said foil about said axis to clean said screen.

Description

July 19, 1966 G. M. DICK 3,261,468
SCREEN CLEANING DEVICE Filed May 17, 1963 4 Sheets-Sheet 1 FIG.
I IL 26 I ||l IIll| IHI l. ll h July 19, 1966 G. M. DICK SCREEN CLEANING DEVICE 4 Sheets-Sheet 2 Filed May 17, 1963 FIG. 5
July 19, 1966 mcK 3,261,468
SCREEN CLEANING DEVICE Filed May 17. 1963 4 Sheets-Sheet 3 F IG. 4 I
July 19, 1966 e. M. DICK SCREEN CLEANING DEVICE 4 Sheets-Sheet 4.
Filed May 17, 1963 United States Patent .0
3,261,468 SCREEN CLEANING DEVICE George M. Dick, Sherbrooke, Quebec, Canada, assignor to Bird Machine Company, South Walpole, Mass., a corporation of Massachusetts Filed May 17, 1963, Ser. No. 281,297 7 Claims. (Cl. 209-243) This invention relates to fibrous pulp screening apparatus and more particularly to an improved screen cleaning device for such processing apparatus.
It has previously been proposed to employ a screen cleaning device or foils mounted for movement in a circular path across the face of cylindrical screens to maintain the screens free from obstruction. However, for optimum effectiveness, the clearance between the foils and the screen surface must be quite small and must be maintained uniform along the axis of the screen. This small and uniform clearance has required additional support and reinforcement for the foils, a condition which has tended to decrease the effectiveness of the foils because of the additional turbulence produced in the pulp by movement of the reinforcement therethrough. In addition, such support and reinforcement has presented surfaces against which occasional long strings of fiber have tended to accumulate, forming clumps which produce still further turbulence and power loss.
It is the general object of the present invention to avoid and overcome the foregoing and other difficulties of and objections to prior art practices by the provision of an improved screen cleaning device which eliminates the accumulation of deleterious fibrous bundles and strings in the annular chamber or fiber passageway adjacent the screen or screens of the fibrous pulp screening apparatus; prevents jamming of the screen cleaning device against the screen or screens; prevents clogging of the screen or screens; and permits the fibrous pulp screening apparatus to be operated by a low horsepower drive means.
Another object of the present invention is to provide an improved screen cleaning device which provides uniform pulsing on the adjacent screen along the length of a cleaning foil.
Yet another object of the present invention is to provide an improved screen cleaning device which provides improved direction of undesirable material in the stock toward the reject trap.
Still another object of the present invention is to provide an improved screen cleaning device which provides improved direction of undesirable material in the stock from the adjacent screen.
The aforesaid objects of the present invention, and other objects which will become apparent as the description proceeds, are achieved by providing, in one embodiment of the invention, a screening device for fibrous pulp having a generally cylindrical screen and means for conducting a stream of pulp across a cylindrical face of said screen, an improved screen cleaning device comprising at least one elongated foil supported adjacent one end only thereof for movement in a circular path about the axis of the screen and across a face thereof, the clearance between the foil and the adjacent screen face varying from the supported end to the free end of the foil at rest, the extent of said variation at rest being substantially equal to the extent of bending of said foil under the influence of centrifugal force under operating conditions, and means for rotating said foil about said axis to clean said screen.
The objects of the invention are-achieved in another embodiment of the invention by providing a screen cleaning device in which at least one elongated foil is provided which is supported adjacent one end only thereof for movement in a circular path about the axis of the screen 3,261,468 Patented July 19, 1966 and across a face thereof, the foil being hollow and filled with air or other gas so as to have minimum mass and consequently to be subject to so little stress under the influence of centrifugal force during operation that no appreciable bending occurs; consequently, the hollow foil is mounted so that the clearance between the foil and screen face is uniform along the length of the foil at rest and remains so during operation.
For a better understanding of the present invention, reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:
FIG. 1 is a side elevational view partially in vertical section of a fibrous pulp screening apparatus of the general type shown in US. Patent No. 2,975,899 incorporating the improved screen cleaning device of the present invention; 1
FIG. 2 is an enlarged plan view of the spider taken along the line 2-2 of FIG. 1 in the direction of the arrows;
FIG. 3 is a side elevational view partly broken away along the line 33 of FIG. 2 in the direction of the arrows showing a foil mounting lug for mounting an outer foil;
FIG. 4 is a view partly in vertical section along the line 4-4 of FIG. 3 in the direction of the arrows;
FIG. 5 is a view along the line 55 of FIG. 2 in the direction of the arrows;
FIG. 6 is a view partly in vertical section along the line 6-6 of FIG. 5 in the direction of the arrows;
FIG. 7 is a diagrammatic side elevational view of an inclined straight foil disposed adjacent the inner surface of a screen;
FIG. 8 is a view similar to FIG. 7 of an inclined straight foil disposed adjacent the outer surface of a screen;
FIG. 9 is a view similar to FIG. 7 of a variant in which the screen has a conical face and the foil lies in a true cylindrical surface when at rest;
FIG. 10 is a side elevational view of a helical foil for improved direction of undesirable material in the stock toward the reject trap;
FIG. 11 is a fragmentary view in horizontal section of an outer foil of unique cross-sectional configuration for directing undesirable material in the stock away from the screen;
FIG. 12 is a fragmentary view in horizontal section of an inner foil of unique cross-sectional configuration for directing undesirable material in the stock away from the screen;
FIG. 13 is a fragmentary view corresponding to FIG. 1 showing another embodiment of the invention; and
FIG. 14 is a view in section taken along line 14-14 of FIG. 13.
Although the principles of the present invention are broadly applicable to all types of fibrous pulp screening apparatus, the present invention is particularly adapted for use in conjunction with apparatus for screening paper pulp and hence it has been so illustrated and will be so described.
With specific reference to the form of the present invention illustrated in the drawings, and referring particularly to FIG. 1, a paper pulp screening apparatus of the general type shown in US. Patent No. 2,975,899 is indicated by the reference numeral 10.
This paper pulp screening apparatus 10 comprises an in ner cylindrical screen 12 and outer cylindrical screen 14-, concentrically spaced from each other. Inlet means 16 introduces a stream of liquid suspension under pressure into the top of the annular chamber or fiber passageway 18 defined by the inner screen 12 and outer screen 14. A screen cleaning device such as a pair of inner vanes or foils 20 (FIG. 6) and a pair of outer foils 22 of the present invention are mounted on rotatable foil mounting means, such as a rotatable spider 24, for rotational movement adjacent the inner screen 12 and outer screen 14. Drive means 26 for rotating a spider shaft 28, the spider 24, and the inner foils 20 and outer foils 22 comprises the V-belt pulley 30, connected by conventional means, such as belts 32, to a conventional source of power, such as an electric motor (not shown).
It will be understood that the outer foils 22 are disposed adjacent the inner face of the outer screen 14 and that the inner foils 20 are disposed adjacent the outer face of the inner screen 12. All of the foils, upon rotation of spider 24, are mounted for movement in a circular path about the axis of the screens and across their faces.
The liquid suspension passes through the inner screen 12 and outer screen 14 into an inner annular chamber 34 and outer annular chamber 36, respectively, and thence into delivery means 38 for withdrawing screened liquid suspension from the inner annular chamber 34 and outer annular chamber 36. Reject means 40 accepts rejected material from the fiber passageway 18.
As shown in FIGS. 1 and 2, in order to facilitate removal of the screen cleaning device, the spider 24 has an inner circular mounting plate 42 connected by bolts 44 (FIG. 2) to an outer ring 46 having a plurality of, for example, two inner foil mounting lugs 48 (FIGS. 2, 5, and 6), and two outer foil mounting lugs 50 (FIGS. 2-6) depending therefrom.
Mounting of inclined outer foils 22 Referring to FIG. 4, an outer foil 22 is mounted at an angle B with respect to the axis of rotation of the spider 24 by means of shims 52 disposed between the outer foil 22 and outer foil mounting lug 50. Bolts 54 and a key 56 on the outer foil 22 projecting into a keyway 58 in the outer foil mounting lug 50 secure the outer foil 22 at the desired angle B with respect to the axis of rotation.
It will be understood by those skilled in the art that the outer foil 22 may be also mounted at an angle B with respect to the axis of rotation without the necessity of using shims by appropriate tapering of the contact surfaces 60, 62 of the lug or foil respectively. As a result of the angular mounting of the foils, the clearance between each foil and the adjacent screen surface, when the foil is at rest, is not uniform but varies along the length of the foil, increasing toward the free end of the foil. This variation is substantially equal to the extent of distortion or bending of the foil under the influence of centrifugal force under operating conditions, i.e., when the foils are swept across the faces of the screens by rotation of spider 24 to clean the screens of any accumulated pulp.
Further, so that undesirable material in the stock may be directed away from the screen, such as outer screen 14 (FIG. 11) or inner screen 12 (FIG. 12) when rotation is in the direction of the arrows, faces 662 and 660 respectively arranged at an angle with respect to the screen surfaces may be provided on outer foil 220 and inner foil 200.
Mounting 0f inclined inner foils As shown in FIG. 6, an inner foil 20 may be similarly mounted at an angle B with respect to the axis of rotation of the spider 24 by the use of shims 552, bolts 542, key 562, and keyway 582. In the case of the inner foils, the variation in clearance decreases toward the free end of each foil.
The angles B and B may be calculated readily in any particular case by computing the centrifugal force under intended operating conditions and the deflection caused by the force for given materials of construction and dimensions. The centrifugal force F in pounds is computed as follows:
where W=weight of the foil in pounds N :revolutions per minute R=radius of rotation in feet g:32.2
If for example:
The deflection S in inches of the free end of the foil is computed as follows:
=398 lbs.
If for example:
B =04. The angle B or B of course, is a function of S and L.
Operation As shown in FIG. 7 the outer foil 22 disposed at the angle B with respect to the axis of rotation is rotated at a speed suflicient to produce an area of reduced pressure between the outer screen 14 and the outer foil 22, the outer foil 22 has moved from the solid line position shown in FIG. 7 to the dotted line position shown in such figure substantially parallel to the axis of rotation, thus providing normal pulsing along the entire length of the outer screen 14.
Reference to FIG. 8 will indicate that the inner foil 20 operates in a similar manner with respect to the inner screen 12.
For the purpose of more efficiently directly undesirable material in the stock toward the reject trap, an inclined foil, such as an inner foil 20 (FIG. 10), may he formed as a portion of a helix having a steep pitch angle a with respect to the axis of rotation.
It will also be understood that the desired results can be obtained by employing a screen, the face of which is part of a conical surface, in combination with conventional foils which themselves lie in a true cylindrical surface when at rest, provided that the angle between the screen and the foil is as set forth above, as shown in FIG. 9 for the case of the outer foil.
It will be apparent from the foregoing that when the mass of the foil is reduced by constructing it of a low density material such as aluminum, titanium, or a nonmetallic synthetic plastic or by making the foil of hollow construction, the magnitude of angle B or B may be reduced. Indeed, in the case of hollow foils, the mass of the foil may be reduced to the point where angle B or B may be zero for all practical purposes. In the embodiment shown in FIGS. 13 and 14, outer foil 250 is hollow, being made from sheet metal, e.g., austenitic stainless steel, and hermetically sealed so that it contains only air or other gas. The low mass of foil 250 so reduces stress on the foil due to centrifugal force during operation that no appreciable bending of the foil occurs and the clearance between the foil and the screen remains substantially uniform both when the foil is at rest and when it is in operation.
It will be recognized by those skilled in the art that the objects of the present invention have been achieved by providing an improved screen cleaning device which eliminates the accumulation of deleterious fibrous bundles and strings in the fiber passageway adjacent the screen of a fibrous pulp screening apparatus, prevents jamming of the screen cleaning device against the screen, prevents clogging of the screen, and permits the operation of the fibrous pulp screening apparatus by a low horsepower drive means. Further, the improved screen cleaning device provides uniform pulsing on the adjacent screen. In addition, such improved screen cleaning device provides improved direction of undesirable material in the stock both toward the reject trap and away from the screen.
While in accordance with the patent statutes preferred and alternative embodiments of the present invention have been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.
What is claimed is:
1. In a screening device for fibrous pulp having a generally cylindrical screen, and means for conducting a stream of pulp across a face of said screen, an improved screen cleaning device comprising at least one elongated foil, means for supporting said foil adjacent one end only for movement in a circular path about the axis of the screen and across a face thereof and spaced from said face, the clearance between the foil and the adjacent screen face varying from the supported end to the free end of the foil at rest, the extent of said variation at rest being substantially equal to the extent of bending of said foil under the influence of centrifugal force under operating conditions, so that under operating conditions, the clearance between said foil and said screen is substantially uniform, and: means for rotating said foil about said axis to clean said screen.
2. A screening device as claimed in claim 1 in which said foil is of helical configuration.
3. A screening device as claimed in claim 2 in which said foil is mounted for movement across the inner face of said screen and the clearance increases toward the free end.
4. A screening device as claimed in claim 2 in which said foil is mounted for movement across the outer face of said screen and the clearance decreases toward the free end.
5. A screening device as claimed in claim 1 in which said screen is exactly cylindrical.
6. A screening device as claimed in claim 1 in which said screen at least in part has a slightly conical surface.
7. In a screening device for fibrous pulp having a generally cylindrical screen and means for conducting a stream of pulp across a face of said screen, an improved screen cleaning device comprising at least one elongated foil supportedadjacent one end only for movement in a circular path about the axis of the screen and across a face thereof, the clearance between the foil and the adjacent screen face being uniform along the length of the foil at rest, said foil being hollow and hermetically sealed and containing essentially only a gaseous fluid in its interior to minimize its mass and the extent of bending of said foil under the influence of centrifugal force under operating conditions, and means for rotating said foil about said axis to clean said screen.
References Cited by the Examiner UNITED STATES PATENTS 439,700 11/ 1890 Stevens 210-374 641,773 1/ 1900 Hoeschen 233-7 2,204,349 6/ 1940 F-orrest 210-415 2,247,605 7/ 1941 Casagrande 210-374 2,796,809 6/1957 Sprau 209-306 2,868,500 1/1959 Boulet 253-39.15 2,975,899 3/1961 Cannon 209-273 FOREIGN PATENTS 28,226 1 1/ 1906 Austria. 24,801 2/ 1883 Germany. 822,325 10/ 1951 Germany. 773,742 5/ 1957 Great Britain.
HARRY B. THORNTON, Primary Examiner.
R. HALPER, Assistant Examiner.

Claims (1)

1. IN A SCEENING DEVICE FOR FIBROUS PULP HAVING A GENERALLY CYLINDRICAL SCREEN, AND MEANS FOR CONDUCTING A STREAM OF PULP ACROSS A FACE OF SAID SCREEN, AN IMPROVED SCREEN CLEANING DEVICE COMPRISING AT LEAST ONE ELONGATED FOIL, MEANS FOR SUPPORTING SAID FOIL ADJACENT ONE END ONLY FOR MOVEMENT IN A CIRCULAR PATH ABOUT THE AXIS OF THE SCREEN AND ACROSS A FACE THEREOF AND SPACED FROM SAID FRAME, THE CLEARANCE BETWEEN THE FOIL AND THE ADJACENT SCREEN FACE VARYING FROM THE SUPPORT END TO THE FREE END OF THE FOIL AT REST, THE EXTENT OF SAID VARIATION AT REST BEING SUBSTANTIALLY EQUAL TO THE EXTENT OF BENDING OF SAID FOIL UNDER THE INFLUENCE OF CENTRIFUGAL FORCE UNDER OPERATING CONDITIONS, SO THAT UNDER OPER-
US281297A 1963-05-17 1963-05-17 Screen cleaning device Expired - Lifetime US3261468A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
DENDAT1250726D DE1250726B (en) 1963-05-17 Cleaning device for drum screens
US281297A US3261468A (en) 1963-05-17 1963-05-17 Screen cleaning device
FI641032A FI42789C (en) 1963-05-17 1964-05-13 Screening apparatus for screening pulp or the like
GB20093/64A GB1032969A (en) 1963-05-17 1964-05-14 Screening device
GB33312/65A GB1032970A (en) 1963-05-17 1964-05-14 Screening device
SE5956/64A SE313986B (en) 1963-05-17 1964-05-15
SE00988/68A SE339613B (en) 1963-05-17 1968-01-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US281297A US3261468A (en) 1963-05-17 1963-05-17 Screen cleaning device

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US3261468A true US3261468A (en) 1966-07-19

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US281297A Expired - Lifetime US3261468A (en) 1963-05-17 1963-05-17 Screen cleaning device

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US (1) US3261468A (en)
DE (1) DE1250726B (en)
FI (1) FI42789C (en)
GB (2) GB1032969A (en)
SE (2) SE313986B (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3387708A (en) * 1966-01-24 1968-06-11 Beloit Corp Paper machine screen
US3420373A (en) * 1966-04-01 1969-01-07 Allen Bruce Hunter Pulp screens
US3446354A (en) * 1966-12-19 1969-05-27 Celleco Ab Method for fractionating a suspension of solid particles
US3759392A (en) * 1972-02-03 1973-09-18 Yhtyneet Paperitehtaat Oy Pressure straining device
US4097374A (en) * 1977-01-26 1978-06-27 Canadian Ingersoll-Rand Co. Ltd. Screening apparatus hydrofoil
US4396502A (en) * 1982-03-18 1983-08-02 Beloit Corporation Screening apparatus for a papermaking machine
US4604193A (en) * 1983-03-25 1986-08-05 E Et M Lamort S.A. Method and apparatus for sorting out a mixture of paper pulp and contaminants
US6030531A (en) * 1997-09-02 2000-02-29 Gershenson; Moshe Filter element assembly
US6511598B2 (en) 1997-09-02 2003-01-28 Moshe Gershenson Concentrically arranged filter element assembly
US6550620B2 (en) 2000-02-04 2003-04-22 Mitsubishi Heavy Industries, Ltd. Pulp screening device
US20040124129A1 (en) * 2002-12-31 2004-07-01 H-Tech, Inc. Filter element assembly and parts therefor
US7837875B2 (en) 2005-08-31 2010-11-23 Eaton Corporation Fluid filter
DE102011086205A1 (en) 2010-11-12 2012-05-16 Metso Paper, Inc. Wing for fiber mass sorter used for manufacturing e.g. paper, has adjustable fins that are arranged at end portions of wing, to prevent ejection of fiber mass over ends of wing
CN113584923A (en) * 2021-09-01 2021-11-02 安德里茨（中国）有限公司 Pulp screening machine

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3635767A1 (en) * 1986-10-21 1988-04-28 Albert Baehr PRE-DRAINAGE LEVEL FOR DRAINING SLUDGE AND SIMILAR SUBSTANCES
DE3734974A1 (en) * 1986-10-21 1989-04-20 Baehr Albert DEVICE FOR DRAINING SLUDGE AND SIMILAR SUBSTANCES
FI80736B (en) * 1989-02-16 1990-03-30 Tampella Oy Ab FOERFARANDE FOER SORTERING AV MASSASUSPENSION OCH SORTERINGSAPPARAT.
DE29515338U1 (en) * 1995-09-25 1995-11-23 Fiedler Heinrich Gmbh Wings for sorting devices

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DE24801C (en) * H. BETCHE in Berlin, Hollmannstr. 6 pt Device for removing the suspended matter that accumulates on the walls of centrifuges for cleaning waste water
US439700A (en) * 1890-11-04 Centrifugal pulp-drier
US641773A (en) * 1899-05-13 1900-01-23 Henry Hoeschen Centrifugal machine.
AT28226B (en) * 1904-10-31 1907-04-25 Hans Stub Centrifugal sorter for wood pulp or the like.
US2204349A (en) * 1937-05-11 1940-06-11 Forrest William James Filtering or straining or like treatment of fluids
US2247605A (en) * 1937-04-15 1941-07-01 Casagrande Aldo Centrifugal drier for textile fibers
DE822325C (en) * 1950-08-20 1951-11-26 F H Schule G M B H Separating classifier with vertical classifier
GB773742A (en) * 1954-07-19 1957-05-01 Luwa Ag A thin-layer evaporator with high-speed agitating means
US2796809A (en) * 1954-07-06 1957-06-25 Nat Gypsum Co Pulp screening apparatus
US2868500A (en) * 1949-02-15 1959-01-13 Boulet George Cooling of blades in machines where blading is employed
US2975899A (en) * 1957-04-16 1961-03-21 Bird Machine Co Screening device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE24801C (en) * H. BETCHE in Berlin, Hollmannstr. 6 pt Device for removing the suspended matter that accumulates on the walls of centrifuges for cleaning waste water
US439700A (en) * 1890-11-04 Centrifugal pulp-drier
US641773A (en) * 1899-05-13 1900-01-23 Henry Hoeschen Centrifugal machine.
AT28226B (en) * 1904-10-31 1907-04-25 Hans Stub Centrifugal sorter for wood pulp or the like.
US2247605A (en) * 1937-04-15 1941-07-01 Casagrande Aldo Centrifugal drier for textile fibers
US2204349A (en) * 1937-05-11 1940-06-11 Forrest William James Filtering or straining or like treatment of fluids
US2868500A (en) * 1949-02-15 1959-01-13 Boulet George Cooling of blades in machines where blading is employed
DE822325C (en) * 1950-08-20 1951-11-26 F H Schule G M B H Separating classifier with vertical classifier
US2796809A (en) * 1954-07-06 1957-06-25 Nat Gypsum Co Pulp screening apparatus
GB773742A (en) * 1954-07-19 1957-05-01 Luwa Ag A thin-layer evaporator with high-speed agitating means
US2975899A (en) * 1957-04-16 1961-03-21 Bird Machine Co Screening device

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3387708A (en) * 1966-01-24 1968-06-11 Beloit Corp Paper machine screen
US3420373A (en) * 1966-04-01 1969-01-07 Allen Bruce Hunter Pulp screens
US3446354A (en) * 1966-12-19 1969-05-27 Celleco Ab Method for fractionating a suspension of solid particles
US3759392A (en) * 1972-02-03 1973-09-18 Yhtyneet Paperitehtaat Oy Pressure straining device
US4097374A (en) * 1977-01-26 1978-06-27 Canadian Ingersoll-Rand Co. Ltd. Screening apparatus hydrofoil
US4396502A (en) * 1982-03-18 1983-08-02 Beloit Corporation Screening apparatus for a papermaking machine
US4604193A (en) * 1983-03-25 1986-08-05 E Et M Lamort S.A. Method and apparatus for sorting out a mixture of paper pulp and contaminants
US6030531A (en) * 1997-09-02 2000-02-29 Gershenson; Moshe Filter element assembly
US6238560B1 (en) 1997-09-02 2001-05-29 Moshe Gershenson Collapsible filter element assembly
US6511598B2 (en) 1997-09-02 2003-01-28 Moshe Gershenson Concentrically arranged filter element assembly
US7001517B2 (en) 1997-09-02 2006-02-21 Moshe Gershenson Collapsible filter element
US6585893B2 (en) 1997-09-02 2003-07-01 Moshe Gershenson Concentrically-arranged, multi-sleeve bag-type filter element assembly
US6585892B2 (en) 1997-09-02 2003-07-01 Moshe Gershenson Concentrically-arranged flexible media and support basket with second stage cartridge filter
US6706198B2 (en) 1997-09-02 2004-03-16 Moshe Gershenson Liquid filtering in concentric filter sleeve assembly
US6712967B2 (en) 1997-09-02 2004-03-30 Moshe Gershenson Liquid filter assembly with concentric filter sleeves of bag-type media
US6550620B2 (en) 2000-02-04 2003-04-22 Mitsubishi Heavy Industries, Ltd. Pulp screening device
US20040124129A1 (en) * 2002-12-31 2004-07-01 H-Tech, Inc. Filter element assembly and parts therefor
US7837875B2 (en) 2005-08-31 2010-11-23 Eaton Corporation Fluid filter
DE102011086205A1 (en) 2010-11-12 2012-05-16 Metso Paper, Inc. Wing for fiber mass sorter used for manufacturing e.g. paper, has adjustable fins that are arranged at end portions of wing, to prevent ejection of fiber mass over ends of wing
CN113584923A (en) * 2021-09-01 2021-11-02 安德里茨（中国）有限公司 Pulp screening machine

Also Published As

Publication number Publication date
GB1032969A (en) 1966-06-15
SE313986B (en) 1969-08-25
FI42789B (en) 1970-06-30
GB1032970A (en) 1966-06-15
FI42789C (en) 1970-10-12
SE339613B (en) 1971-10-11
DE1250726B (en) 1967-09-21

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