WO1992016311A1 - A roller screen for screening bulk material, especially wood chips - Google Patents

A roller screen for screening bulk material, especially wood chips Download PDF

Info

Publication number
WO1992016311A1
WO1992016311A1 PCT/FI1992/000038 FI9200038W WO9216311A1 WO 1992016311 A1 WO1992016311 A1 WO 1992016311A1 FI 9200038 W FI9200038 W FI 9200038W WO 9216311 A1 WO9216311 A1 WO 9216311A1
Authority
WO
WIPO (PCT)
Prior art keywords
rollers
roller
grooves
screened
teeth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI1992/000038
Other languages
French (fr)
Inventor
Mikko Jokinen
Timo Kurki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Consilium Bulk Babcock Oy
Original Assignee
Consilium Bulk Babcock Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Consilium Bulk Babcock Oy filed Critical Consilium Bulk Babcock Oy
Priority to US08/117,183 priority Critical patent/US5377848A/en
Priority to BR9205793A priority patent/BR9205793A/en
Priority to DE69211684T priority patent/DE69211684T2/en
Priority to JP4504979A priority patent/JP2527522B2/en
Priority to CS931963A priority patent/CZ196393A3/en
Priority to EP92904706A priority patent/EP0576437B1/en
Publication of WO1992016311A1 publication Critical patent/WO1992016311A1/en
Priority to NO933106A priority patent/NO180523C/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B07B1/12—Apparatus having only parallel elements
    • B07B1/14—Roller screens
    • B07B1/15—Roller screens using corrugated, grooved or ribbed rollers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/02—Pretreatment of the raw materials by chemical or physical means
    • D21B1/023—Cleaning wood chips or other raw materials

Definitions

  • the invention relates to a roller screen for separating finer and coarser material fractions of bulk material from each other, especially for separating sawdust from wood chips, the roller screen comprising a plurality of successive rollers rotating about parallel axes of rotation, the upper surfaces of the rollers providing a path for the material to be screen ⁇ ed; at least one drive means for rotating the rollers; and a means for feeding the material to be screened to the infeed end of said path.
  • the roller screen according to the invention can be used e.g. in the production of cellulose for screening wood chips used as process feed.
  • a disc screen consists of successive shafts to which discs are attached at regular intervals in such a manner that the discs on successive shafts interdigitate. The shafts rotate at the same rate and to the same direction.
  • the upper surface of the discs functions as a conveyor of the material to be screened and between the discs there is a gap determined by the grain size desired, the finer fraction falling through the screen at the gap while the coarser fraction passes on to the discharge end of the screen.
  • Previously known disc screens are described e.g. in Finnish Patent Application 780,685 and Finnish Published Specification 70,379.
  • a roller screen comprises rotating rollers in ⁇ stead of disc shafts.
  • a disc screen is ill-suited for separation of particulate sawdust of a grain size of less than 3 to 5 mm from wood chips since the particles falling between the discs may be of any length although their thickness is not greater than the gap between the discs. This results in loss of pulpwood, which is useful e.g. in a process for producing cellulose, together with the sawdust removed from wood chips.
  • the object of the present invention is to remedy the above drawbacks by improving the construction of the known roller screen.
  • This is achieved with the roller screen according to the invention, which is char ⁇ acterized in that there are radial and essentially axial grooves on the surface of the rollers, the grooves form ⁇ ing teeth onto the surface of the rollers, and that the teeth of each roller interdigitate with the radial grooves of the adjacent roller, whereby the teeth and radial grooves form slots between them for the particles of the material to be screened.
  • the invention is based on the idea that the surface of the rollers is grooved in such a manner that slots of the grain size desired are formed between the rollers, the slots "closing" momentarily when the rollers rotate in such a manner that the particles of the wrong size do not pass through the screen.
  • roller screen of the invention only the particles that are of the grain size selected or smaller than that pass through the screen at the slots that are precisely of the grain size selected. Elongated particles that are bigger than the grain size desired cannot pass through the screen.
  • the power demand of this roller screen is smaller and the wear of the screening means is not as heavy as in a disc screen since the contact surface between the screening means and the material to be screened is small.
  • the construction of the roller screen is simple and the production costs are reason ⁇ able.
  • Figure 1 shows a side view of the roller screen according to the invention
  • Figure 2 shows a top view of the roller screen according to the invention
  • Figure 3 shows a top view of interdigitation of two screening rollers that are used in the roller screen of the above Figures
  • Figure 4 shows the screening roller of Figure
  • Figure 5 shows a magnified view of the point X of Figure 3.
  • Figure 6 shows formation of particle slots between two adjacent screening rollers.
  • the roller screen according to Figures 1 and 2 comprises a framework 1, screening rollers 2 for the material to be screened, a drive means 3 for driving the screening rollers 2 and a hopper 4 for feeding the material to be screened onto the rollers 2.
  • the rollers 2 are mounted side-by-side in the horizontal direction on the upper part of the framework 1 in such a manner that they rotate about parallel axes of rotation.
  • the upper surfaces of the rollers 2 provide a path for the material to be screened, and the material to be screened is to be fed from the hopper 4 to the infeed end of said path.
  • the clearance between the teeth 7 and the grooves 5 and 6 is as small as possible, i.e. of the size that the rollers 2 can rotate without touching one another. All the rollers 2 rotate to the same direction. Most appropriately the radial grooves 5 and axial grooves 6 in the same roller 2 are equal in depth.
  • the bulk material to be screened is dropped onto the arrangement of rollers at the infeed end of the apparatus.
  • the rotating rollers 2 convey the material forward on the upper surface thereof toward the discharge end of the apparatus.
  • the small particles fitting into the tooth clearances of the rollers 2 pass on to the bottom side of the rollers, i.e. through the apparatus, at the slots 8 formed by the tooth clear- ances and the grooves 5 and 6 of the adjacent roller.
  • the particles that are bigger than the grain size desired are conveyed on top of the rollers 2 to the discharge end of the apparatus.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Combined Means For Separation Of Solids (AREA)
  • Debarking, Splitting, And Disintegration Of Timber (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)
  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Pulleys (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Feeding And Guiding Record Carriers (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)
  • Dental Preparations (AREA)

Abstract

The invention relates to an apparatus for separating finer and coarser material fractions of bulk material from each other, especially for separating sawdust from wood chips, the apparatus comprising a plurality of successive rollers (2) rotating about parallel axes of rotation, the upper surfaces of the rollers providing a path for the material to be screened; at least one drive means for rotating the rollers (2); and a means for feeding the material to be screened to the infeed end of said path. There are radial and essentially axial grooves (5, 6) on the surface of the rollers (2), the grooves forming teeth (7) onto the surface of the rollers (2), and the teeth (7) of each roller (2) interdigitate with the radial grooves (5) of the adjacent roller (2), whereby the teeth (7) and radial grooves (5) form slots (8) between them for the particles of the material to be screened. With this construction it is possible to prevent the particles that are bigger than the grain size desired from passing through the screen.

Description

A roller screen for screening bulk material, especially wood chips
The invention relates to a roller screen for separating finer and coarser material fractions of bulk material from each other, especially for separating sawdust from wood chips, the roller screen comprising a plurality of successive rollers rotating about parallel axes of rotation, the upper surfaces of the rollers providing a path for the material to be screen¬ ed; at least one drive means for rotating the rollers; and a means for feeding the material to be screened to the infeed end of said path. The roller screen according to the invention can be used e.g. in the production of cellulose for screening wood chips used as process feed.
Known apparatuses for screening bulk material include disc screens and various roller screens. A disc screen consists of successive shafts to which discs are attached at regular intervals in such a manner that the discs on successive shafts interdigitate. The shafts rotate at the same rate and to the same direction. The upper surface of the discs functions as a conveyor of the material to be screened and between the discs there is a gap determined by the grain size desired, the finer fraction falling through the screen at the gap while the coarser fraction passes on to the discharge end of the screen. Previously known disc screens are described e.g. in Finnish Patent Application 780,685 and Finnish Published Specification 70,379. A roller screen comprises rotating rollers in¬ stead of disc shafts. Between the rollers is a gap determined by the grain size desired, the finer material fraction falling through the screen at the gap while the coarser fraction passes on to the discharge end of the screen on the upper surface of the rollers. Drawbacks of disc screens are a great demand of power and heavy wear of discs, which are due to the large contact surface of the discs and the material to be screened. A disc screen is ill-suited for separation of particulate sawdust of a grain size of less than 3 to 5 mm from wood chips since the particles falling between the discs may be of any length although their thickness is not greater than the gap between the discs. This results in loss of pulpwood, which is useful e.g. in a process for producing cellulose, together with the sawdust removed from wood chips.
The same drawback is also found in known roller screens since the particles falling through the gap between the rollers may be of considerable length in the axial direction of the rollers although their thickness is not greater than the gap.
The object of the present invention is to remedy the above drawbacks by improving the construction of the known roller screen. This is achieved with the roller screen according to the invention, which is char¬ acterized in that there are radial and essentially axial grooves on the surface of the rollers, the grooves form¬ ing teeth onto the surface of the rollers, and that the teeth of each roller interdigitate with the radial grooves of the adjacent roller, whereby the teeth and radial grooves form slots between them for the particles of the material to be screened.
The invention is based on the idea that the surface of the rollers is grooved in such a manner that slots of the grain size desired are formed between the rollers, the slots "closing" momentarily when the rollers rotate in such a manner that the particles of the wrong size do not pass through the screen.
Thus, in the roller screen of the invention only the particles that are of the grain size selected or smaller than that pass through the screen at the slots that are precisely of the grain size selected. Elongated particles that are bigger than the grain size desired cannot pass through the screen. This is the most significant advantage of the roller screen of the inven¬ tion in regard to the known apparatuses. In addition, the power demand of this roller screen is smaller and the wear of the screening means is not as heavy as in a disc screen since the contact surface between the screening means and the material to be screened is small. Furthermore, the construction of the roller screen is simple and the production costs are reason¬ able.
In the following the invention will be described in greater detail by means of an advantageous embodiment by way of example with reference to the attached drawings wherein
Figure 1 shows a side view of the roller screen according to the invention, Figure 2 shows a top view of the roller screen according to the invention,
Figure 3 shows a top view of interdigitation of two screening rollers that are used in the roller screen of the above Figures, Figure 4 shows the screening roller of Figure
3 in the axial direction,
Figure 5 shows a magnified view of the point X of Figure 3, and
Figure 6 shows formation of particle slots between two adjacent screening rollers.
The roller screen according to Figures 1 and 2 comprises a framework 1, screening rollers 2 for the material to be screened, a drive means 3 for driving the screening rollers 2 and a hopper 4 for feeding the material to be screened onto the rollers 2. The rollers 2 are mounted side-by-side in the horizontal direction on the upper part of the framework 1 in such a manner that they rotate about parallel axes of rotation. The upper surfaces of the rollers 2 provide a path for the material to be screened, and the material to be screened is to be fed from the hopper 4 to the infeed end of said path.
As shown in Figures 3 to 6, there are radial and axial grooves 5 and 6 on the surface of the rollers 2, the grooves forming teeth 7 onto the surface of the rollers. The teeth 7 of each roller 2 interdigitate with the radial grooves 5 of the adjacent roller 2, whereby the teeth 7 and the radial grooves 5 form slots 8 between them for the particles of the material to be screened.
The clearance between the teeth 7 and the grooves 5 and 6 is as small as possible, i.e. of the size that the rollers 2 can rotate without touching one another. All the rollers 2 rotate to the same direction. Most appropriately the radial grooves 5 and axial grooves 6 in the same roller 2 are equal in depth.
The bulk material to be screened is dropped onto the arrangement of rollers at the infeed end of the apparatus. The rotating rollers 2 convey the material forward on the upper surface thereof toward the discharge end of the apparatus. The small particles fitting into the tooth clearances of the rollers 2 pass on to the bottom side of the rollers, i.e. through the apparatus, at the slots 8 formed by the tooth clear- ances and the grooves 5 and 6 of the adjacent roller. The particles that are bigger than the grain size desired are conveyed on top of the rollers 2 to the discharge end of the apparatus. When the rollers 2 rotate, all the slots 8 momentarily "close" each in turn, wherefore only a particle fitting into said slots can pass through the screen.
The invention has been described above only by means of one advantageous embodiment, describing a roller screen that is particularly well suited for screening of wood chips. All the slots 8 can be of the same size. Said roller screen can naturally also be used for screening other bulk material and for sorting it in accordance with the grain size, whereby the size of the slots can increase toward the discharge end of the arrangement of rollers. It is also possible for one skilled in the art to carry out other details of the invention in various ways without deviating from the scope of the invention defined by the claims.

Claims

Claims
1. A roller screen for separating finer and coarser material fractions of bulk material from each other, especially for separating sawdust from wood chips, the roller screen comprising a plurality of successive rollers (2) rotating about parallel axes of rotation, the upper surfaces of the rollers providing a path for the material to be screened; at least one drive means (3) for rotating the rollers (2); and a means (4) for feeding the material to be screened to the infeed end of said path, c h a r a c t e r i z e d in that there are radial and essentially axial grooves (5, 6) on the surface of the rollers (2), the grooves form- ing teeth (7) onto the surface of the rollers (2), and that the teeth (7) of each roller (2) interdigitate with the radial grooves (5) of the adjacent roller (2), whereby the teeth (7) and radial grooves (5) form slots (8) between them for the particles of the material to be screened.
2. A roller screen according to claim 1, c h a r a c t e r i z e d in that the radial grooves (5) and axial grooves (6) in the same roller (2) are essentially equal in depth.
3. A roller screen according to claim 1 or 2, c h a r a c t e r i z e d in that the clearance between the teeth (7) and the grooves (5, 6) is as small as possible, which enables the rollers (2) to rotate with¬ out touching one another.
PCT/FI1992/000038 1991-03-21 1992-02-12 A roller screen for screening bulk material, especially wood chips Ceased WO1992016311A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US08/117,183 US5377848A (en) 1991-03-21 1992-02-12 Roller screen for screening bulk material, especially wood chips
BR9205793A BR9205793A (en) 1991-03-21 1992-02-12 Roller sieve
DE69211684T DE69211684T2 (en) 1991-03-21 1992-02-12 ROLLER SCREEN FOR SCREENING BULK MATERIAL, IN PARTICULAR WOODCHIPS
JP4504979A JP2527522B2 (en) 1991-03-21 1992-02-12 Loras screen for separating bulk materials, especially wood chips
CS931963A CZ196393A3 (en) 1991-03-21 1992-02-12 Cylindrical screen for screening loose material, especially shavings
EP92904706A EP0576437B1 (en) 1991-03-21 1992-02-12 A roller screen for screening bulk material, especially wood chips
NO933106A NO180523C (en) 1991-03-21 1993-09-01 Rolling screen for sorting bulk material, especially wood chips

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI911383A FI88118C (en) 1991-03-21 1991-03-21 Rolling screen for sifting bulk cargo material, especially wood chopping
FI911383 1991-03-21

Publications (1)

Publication Number Publication Date
WO1992016311A1 true WO1992016311A1 (en) 1992-10-01

Family

ID=8532165

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1992/000038 Ceased WO1992016311A1 (en) 1991-03-21 1992-02-12 A roller screen for screening bulk material, especially wood chips

Country Status (13)

Country Link
US (1) US5377848A (en)
EP (1) EP0576437B1 (en)
JP (1) JP2527522B2 (en)
AT (1) ATE139467T1 (en)
AU (1) AU646931B2 (en)
BR (1) BR9205793A (en)
CA (1) CA2105176C (en)
CZ (1) CZ196393A3 (en)
DE (1) DE69211684T2 (en)
ES (1) ES2090606T3 (en)
FI (1) FI88118C (en)
NO (1) NO180523C (en)
WO (1) WO1992016311A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10111385B2 (en) 2016-06-24 2018-10-30 Jackrabbit Nut harvester with separating disks
US11432463B2 (en) 2019-02-08 2022-09-06 Jackrabbit, Inc. Nut harvester with a removable assembly and a method of replacing a removable assembly of a nut harvester

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19857498C1 (en) * 1998-12-14 2000-06-15 Siempelkamp Gmbh & Co Roller screen machine and its use
FI111055B (en) * 2001-11-23 2003-05-30 Raumaster Oy Roll screen, apparatus for screening chips and method in roll screen
CA2476194C (en) 2004-07-30 2010-06-22 Suncor Energy Inc. Sizing roller screen ore processing apparatus
US8393561B2 (en) 2005-11-09 2013-03-12 Suncor Energy Inc. Method and apparatus for creating a slurry
CA2640514A1 (en) 2008-09-18 2010-03-18 Kyle Alan Bruggencate Method and apparatus for processing an ore feed
CA2812116C (en) 2009-07-24 2013-12-24 Suncor Energy Inc. Screening disk, roller, and roller screen for screening an ore feed
CN102836828B (en) * 2011-06-21 2015-10-28 刘素华 Mould cloth garbage sorting system
US11396032B2 (en) 2016-08-18 2022-07-26 Outotec (Finland) Oy Self-cleaning roller screen

Citations (5)

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US1677838A (en) * 1926-02-03 1928-07-17 Molin Adolf Gustaf Sizing apparatus for coke or the like
US1941147A (en) * 1931-06-19 1933-12-26 Krupp Ag Grusonwerk Classifying apparatus
EP0328067A2 (en) * 1988-02-12 1989-08-16 Acrowood Corporation Machine and method for sorting out fines and over-thick wood chips
US4871073A (en) * 1987-10-02 1989-10-03 National Ecology, Inc. Disc screen separator device
US4901864A (en) * 1988-08-16 1990-02-20 International Paper Company Grooved spacer for disc screen wood chip sorter

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NL36554C (en) *
US2966267A (en) * 1958-08-21 1960-12-27 James R Dunbar Apparatus for materials classification
US3870627A (en) * 1972-11-27 1975-03-11 John W Herkes Mechanical screening device for machine-harvested sugar cane
US3817375A (en) * 1973-02-28 1974-06-18 J Herkes Separating device
US4301930A (en) * 1979-09-24 1981-11-24 Radar Companies, Inc. Disk screen, modular disk assembly and method
US4658964A (en) * 1985-09-03 1987-04-21 Williams Patent Crusher And Pulverizer Company Rotary disc screen and method of operation
US4755286A (en) * 1987-07-30 1988-07-05 Beloit Corporation Split flow `V` screen
US4903845A (en) * 1988-02-12 1990-02-27 Acrowood Corporation Machine and method for separating fines from wood chips
US4836388A (en) * 1988-04-27 1989-06-06 Beloit Corporation Apparatus for separating material by length

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1677838A (en) * 1926-02-03 1928-07-17 Molin Adolf Gustaf Sizing apparatus for coke or the like
US1941147A (en) * 1931-06-19 1933-12-26 Krupp Ag Grusonwerk Classifying apparatus
US4871073A (en) * 1987-10-02 1989-10-03 National Ecology, Inc. Disc screen separator device
EP0328067A2 (en) * 1988-02-12 1989-08-16 Acrowood Corporation Machine and method for sorting out fines and over-thick wood chips
US4901864A (en) * 1988-08-16 1990-02-20 International Paper Company Grooved spacer for disc screen wood chip sorter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10111385B2 (en) 2016-06-24 2018-10-30 Jackrabbit Nut harvester with separating disks
US11432463B2 (en) 2019-02-08 2022-09-06 Jackrabbit, Inc. Nut harvester with a removable assembly and a method of replacing a removable assembly of a nut harvester

Also Published As

Publication number Publication date
NO933106D0 (en) 1993-09-01
FI88118B (en) 1992-12-31
DE69211684D1 (en) 1996-07-25
US5377848A (en) 1995-01-03
CA2105176A1 (en) 1992-09-22
ES2090606T3 (en) 1996-10-16
BR9205793A (en) 1994-06-28
ATE139467T1 (en) 1996-07-15
EP0576437A1 (en) 1994-01-05
EP0576437B1 (en) 1996-06-19
CA2105176C (en) 1997-05-13
NO933106L (en) 1993-09-16
CZ196393A3 (en) 1994-03-16
FI911383A0 (en) 1991-03-21
JPH06501421A (en) 1994-02-17
AU646931B2 (en) 1994-03-10
FI88118C (en) 1993-04-13
FI911383A7 (en) 1992-09-22
NO180523C (en) 1997-05-14
AU1264992A (en) 1992-10-21
JP2527522B2 (en) 1996-08-28
NO180523B (en) 1997-01-27
DE69211684T2 (en) 1996-10-31

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