EP0221900B1 - A method of breaking up bundles of adherent hard fibers and an oscillating screen - Google Patents

A method of breaking up bundles of adherent hard fibers and an oscillating screen Download PDF

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Publication number
EP0221900B1
EP0221900B1 EP85903418A EP85903418A EP0221900B1 EP 0221900 B1 EP0221900 B1 EP 0221900B1 EP 85903418 A EP85903418 A EP 85903418A EP 85903418 A EP85903418 A EP 85903418A EP 0221900 B1 EP0221900 B1 EP 0221900B1
Authority
EP
European Patent Office
Prior art keywords
fibers
screen
openings
bundles
plane
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.)
Expired - Lifetime
Application number
EP85903418A
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German (de)
French (fr)
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EP0221900A1 (en
Inventor
Sven Axelsson
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Vertex International AB
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Vertex International AB
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Publication date
Application filed by Vertex International AB filed Critical Vertex International AB
Publication of EP0221900A1 publication Critical patent/EP0221900A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
    • B28C5/40—Mixing specially adapted for preparing mixtures containing fibres
    • B28C5/404—Pre-treatment of fibres

Definitions

  • This invention is concerned with a method of breaking up bundles of adherent hard fibers, especially steel fibers, and feeding said defibered or individualized fibers to a mixing device and a vibrating screen for performing said method.
  • Swedish laid open patent application No. 7508720-5 discloses a method and a device to break up the bundles of fibers by vibrating and/or tumbling on a screen and/or in a tumbler.
  • the feed rate of the fibers to the mixer is varied by an increase or decrease of the rate of motion of the screen or tumbler and/or the discharge opening of the tumbler.
  • the fibers are oriented in a plane by falling by gravity on a vibrating table and thereafter aligned by an airstream in a transport pipe.
  • DE-A-2 523 905 and DE-A-2 337 129 both disclose a method of breaking up bundles of adherent hard fibers, particularly steel fibers, and feeding said defibered or individualized fibers to a mixing device, the method comprising vibrating said bundles of adhering fibers on an oscillating screen to obtain separated fibers, passing said separated fibers through openings of said screen, and supplying by means of gravity and oscillating force said fibers to said mixing device.
  • the purpose of the present invention is to suggest a simple method of defibering fibers obtained as bundles and of supplying the individualized fibers by gravity over a large area, said area being larger than the area of the oscillating screen, and directly to a mixing device.
  • the invention also comprises a screen for performing said method.
  • the purpose of the invention is achieved by a method according to the preamble of claim 1 in that said openings being oblong and through which openings only one fiber at a time can pass, said fibers being spread over a large area, said area being larger than the area of said screen and being part of said mixing device, separated fibers are aligned in a plane parallel to the plane of said screen thus lying horizontally when passing through opening.
  • the screen for performing the method comprises an oscillating screen according to the preamble of claim 2 wherein, said openings being oblong and having a length corresponding mainly to the length of said fibers, the width of said openings being essentially less than the length of said fibers, the plane of each opening making an acute angle relative to the plane of the screening means and the line corresponding to the longest dimension of an opening being parallel to the plane of the screen.
  • Figure 1 shows a cross section through a concrete mixer station comprising a screen according to the invention and Figure 2 shows the concrete mixer station from above.
  • the concrete mixer station of Figure 1 comprises a mixing means 1 having mixing elements which are not shown, said elements being driven by a motor 2.
  • a screen 3 is arranged on the mixing means 1, said screen has a screening means 4.
  • the screening means is given an oscillating movement by a motor 5 via an eccentric member 6.
  • Said screening means 4 has oblong openings 8, e.g. rhombic openings as shown in Figure 2.
  • the screen 3 is provided with side walls 7 to retain the fibers supplied to the screen when the screening means is moving backwards and forwards.
  • the screening means 4 covers a large area of the mixing means 1.
  • the width of the screening means is about half the radius of the round mixing tank 1.
  • the screening means has such a length that all fibers fall within the mixing tank 1.
  • the screen can of course be placed nearer the center of the mixing tank and thus having both a greater length and width.
  • the openings of the screening means must be oblong and preferably have rhomboidic shape, i.e. the openings include both rectangular and rhombic shape.
  • the shape of the openings must have such a shape that only one fiber at a time can pass through one and the same opening.
  • the largest dimension of an opening must be of the same order of magnitude as the fiber and the dimension at right angle to the longest dimension must be small such that two or more fiber sticking together can not pass through the opening.
  • a practical least dimension of a rhomboidic opening is such a length that the sum of the length of two adjacent sides is slightly greater than the length of a fiber. In that case, only fibers having a longitudinal axis forming an angle against the plane of the screening means can pass.
  • a preferable practical greatest dimension of rhomboidic openings is such a length that the sum of the length of two adjacent sides is twice the length of the fiber.
  • the width of the openings must be such that in the vast majority of cases bundles of fibers of two or more cannot pass.
  • the surface of the screening means is not even but is provided with elevations and corresponding depressions (negative elevations), i.e. the level of the top surface is having regular or non-regular variations.
  • An example of a preferred screening means is a means made of expanded metal having rhombic openings.
  • the openings of an expanded metal make an acute angle with the plane of the screening means.
  • an expanded metal screen having rhombic openings is very suitable, the openings having a greatest diagonal of 25 mm and a second diagonal of 12 mm. It is understood that the size of the openings depends on the length of the fibers.
  • the fibers are supplied in the form of bundles of fibers and of course, there are single fibers.
  • Such bundles are fed to the screen 3 via an endless chain elevator 9, said screen is placed directly over said mixing tank 1.
  • Simultaneously or preferably in advance naturally moist sand is fed to the mixing means 1.
  • the sand must not be dry. Due to the fact that the fibers pass through said screening means only one fiber at a time passes through one and the same opening, over a large area, the supply of fibers comprises many fibers per unit of time over a large area. Thus many fibers can be supplied without clogging in the mixing tank. Thanks to the fact that the screen is oscillating the fibers obtain a component of movement parallel to the plane of the screening means.
  • the mixing device 1 will distribute the fibers in the concrete before they are able to clog together. Then, or possibly simultaneously with the sand other ballast material, e.g. silicon dioxide is added. Following the ballast materials cement and thereafter water is added forming the mixed concrete. This concrete can be sprayed. This spraying orients the fibers in one direction in the concrete.
  • the sand other ballast material e.g. silicon dioxide
  • the present invention is not limited to the production to reinforced concrete but can be used in the production of other masses containing fibers, e.g. asphalt, bitumen.
  • the method is not limited to the described open mixing device but can be used with other mixing devices, e.g. screw mixing devices.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)
  • Preliminary Treatment Of Fibers (AREA)

Abstract

A method of breaking up bundles of adherent hardfibers, particularly steelfibers and feeding the obtained single fibers to a mixing device. The method comprises vibrating said bundles of adhering fibers on an oscillating screen to obtain separated fibers, passing said separated fibers being aligned in a plane parallel to the plane of said screen through oblong openings of said screen, through which openings in the main only one fiber at a time can pass and supplying by means of gravity and oscillating force said individual fibers to said mixing device spread over a large area, said area being larger than the area of said screen. The screen (4) has oblong openings (8) having a length corresponding mainly to the length of the fibers and a width being essentially less than the length of said fibers.

Description

  • This invention is concerned with a method of breaking up bundles of adherent hard fibers, especially steel fibers, and feeding said defibered or individualized fibers to a mixing device and a vibrating screen for performing said method.
  • It is previously known to admix precut steel fibers with mixed concrete, thereby the fibers have been added to the concrete mix in a concrete mixer. However, such fibers can only be contained in such concrete mix up to a few percent by volume, since the fibers during mixing and transport show a tendency to clog and form clusters with ballast and cement materials.
  • It has been proposed to feed the fibers to the dry cement and ballast materials by an air stream. This method is very advantagous. However, steel and other metal fibers are sold only as precut fibers having a short length. These fibers are packed closely together and form lumps or bundles, the fibers of said bundles stick very hard together and are difficult to separate to individualized fibers.
  • Swedish laid open patent application No. 7508720-5 discloses a method and a device to break up the bundles of fibers by vibrating and/or tumbling on a screen and/or in a tumbler. The feed rate of the fibers to the mixer is varied by an increase or decrease of the rate of motion of the screen or tumbler and/or the discharge opening of the tumbler. The fibers are oriented in a plane by falling by gravity on a vibrating table and thereafter aligned by an airstream in a transport pipe.
  • DE-A-2 523 905 and DE-A-2 337 129 both disclose a method of breaking up bundles of adherent hard fibers, particularly steel fibers, and feeding said defibered or individualized fibers to a mixing device, the method comprising vibrating said bundles of adhering fibers on an oscillating screen to obtain separated fibers, passing said separated fibers through openings of said screen, and supplying by means of gravity and oscillating force said fibers to said mixing device.
  • The purpose of the present invention is to suggest a simple method of defibering fibers obtained as bundles and of supplying the individualized fibers by gravity over a large area, said area being larger than the area of the oscillating screen, and directly to a mixing device. The invention also comprises a screen for performing said method.
  • The purpose of the invention is achieved by a method according to the preamble of claim 1 in that said openings being oblong and through which openings only one fiber at a time can pass, said fibers being spread over a large area, said area being larger than the area of said screen and being part of said mixing device, separated fibers are aligned in a plane parallel to the plane of said screen thus lying horizontally when passing through opening.
  • The screen for performing the method comprises an oscillating screen according to the preamble of claim 2 wherein, said openings being oblong and having a length corresponding mainly to the length of said fibers, the width of said openings being essentially less than the length of said fibers, the plane of each opening making an acute angle relative to the plane of the screening means and the line corresponding to the longest dimension of an opening being parallel to the plane of the screen.
  • Preferred embodiments of the oscillating screen according to the invention are specified in claims 3 to 6.
  • The invention will now be described by means of the drawing.
  • Figure 1 shows a cross section through a concrete mixer station comprising a screen according to the invention and Figure 2 shows the concrete mixer station from above.
  • The concrete mixer station of Figure 1 comprises a mixing means 1 having mixing elements which are not shown, said elements being driven by a motor 2. A screen 3 is arranged on the mixing means 1, said screen has a screening means 4. The screening means is given an oscillating movement by a motor 5 via an eccentric member 6. Said screening means 4 has oblong openings 8, e.g. rhombic openings as shown in Figure 2.
  • The screen 3 is provided with side walls 7 to retain the fibers supplied to the screen when the screening means is moving backwards and forwards. The screening means 4 covers a large area of the mixing means 1. Advantageously it covers an area as large as possible. In Fig. 2 the width of the screening means is about half the radius of the round mixing tank 1. The screening means has such a length that all fibers fall within the mixing tank 1. The screen can of course be placed nearer the center of the mixing tank and thus having both a greater length and width. By varying the number of revolutions of motor 5 the velocity of said screening means can be varied and thus the amount of supplied fibers can be increased or decreased.
  • The openings of the screening means must be oblong and preferably have rhomboidic shape, i.e. the openings include both rectangular and rhombic shape. The shape of the openings must have such a shape that only one fiber at a time can pass through one and the same opening. The largest dimension of an opening must be of the same order of magnitude as the fiber and the dimension at right angle to the longest dimension must be small such that two or more fiber sticking together can not pass through the opening. A practical least dimension of a rhomboidic opening is such a length that the sum of the length of two adjacent sides is slightly greater than the length of a fiber. In that case, only fibers having a longitudinal axis forming an angle against the plane of the screening means can pass. A preferable practical greatest dimension of rhomboidic openings is such a length that the sum of the length of two adjacent sides is twice the length of the fiber. Of course the width of the openings must be such that in the vast majority of cases bundles of fibers of two or more cannot pass. Preferably the surface of the screening means is not even but is provided with elevations and corresponding depressions (negative elevations), i.e. the level of the top surface is having regular or non-regular variations.
  • An example of a preferred screening means is a means made of expanded metal having rhombic openings. The openings of an expanded metal make an acute angle with the plane of the screening means. As an example it may be mentioned that, for fibers having a length of 18 mm, an expanded metal screen having rhombic openings is very suitable, the openings having a greatest diagonal of 25 mm and a second diagonal of 12 mm. It is understood that the size of the openings depends on the length of the fibers.
  • When using the present method the fibers are supplied in the form of bundles of fibers and of course, there are single fibers. Such bundles are fed to the screen 3 via an endless chain elevator 9, said screen is placed directly over said mixing tank 1. Simultaneously or preferably in advance naturally moist sand is fed to the mixing means 1. Thus the sand must not be dry. Due to the fact that the fibers pass through said screening means only one fiber at a time passes through one and the same opening, over a large area, the supply of fibers comprises many fibers per unit of time over a large area. Thus many fibers can be supplied without clogging in the mixing tank. Thanks to the fact that the screen is oscillating the fibers obtain a component of movement parallel to the plane of the screening means. Therefore the fibers are spread over an area which is larger than the area of the screening means. The mixing device 1 will distribute the fibers in the concrete before they are able to clog together. Then, or possibly simultaneously with the sand other ballast material, e.g. silicon dioxide is added. Following the ballast materials cement and thereafter water is added forming the mixed concrete. This concrete can be sprayed. This spraying orients the fibers in one direction in the concrete.
  • The present invention is not limited to the production to reinforced concrete but can be used in the production of other masses containing fibers, e.g. asphalt, bitumen.
  • The method is not limited to the described open mixing device but can be used with other mixing devices, e.g. screw mixing devices.

Claims (6)

1. A method of breaking up bundles of adherent hard fibers, particularly steel fibers, and feeding said defibered or individualized fibers to a mixing device, the method comprising vibrating said bundles of adhering fibers on an oscillating screen to obtain separated fibers, passing said separated fibers through openings in said screen and supplying, by means of gravity and oscillating force, said fibers to said mixing device, characterized in that said openings (8) are oblong and through which openings only one fiber at a time can pass, said fibers being spread over a large area, said area being larger than the area of said screen (4) and being part of said mixing device (1) said separated fibers being aligned in a plane parallel to the plane of said screen (4) thus lying horizontally when passing through one opening (8).
2. An oscillating screen for performing the method of claim 1, the screening means (4) of said oscillating screen having openings (8) through which the separated fibers are passed, characterized in that, said openings (8) being oblong and having a length corresponding mainly to the length of said fibers and a width being essentially less than the length of said fibers, the plane of each opening (8) making an acute angle relative the plane of the screening means, the straight line corresponding to the longest dimension of an opening (8) being parallel to the plane of the screen(4).
3. The screen according to claim 2, characterized in that the openings (8) of the screening means (4) have the form of a rhomb.
4. The screen according to claims 2-3, characterized in that said screening means (4) is made of expanded metal.
5. The screen according to claim 2, characterized in that the openings (8) of the screening means (4) have the form of a rhomboid.
6. The screen according to claim 5, characterized in that the openings (8) of the screening means (4) are rectangular.
EP85903418A 1984-06-15 1985-06-10 A method of breaking up bundles of adherent hard fibers and an oscillating screen Expired - Lifetime EP0221900B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8403237A SE447080B (en) 1984-06-15 1984-06-15 SET AND DEVICE FOR SUPPLY OF FIBERS TO A MIXING DEVICE
SE8403237 1984-06-15

Publications (2)

Publication Number Publication Date
EP0221900A1 EP0221900A1 (en) 1987-05-20
EP0221900B1 true EP0221900B1 (en) 1990-08-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP85903418A Expired - Lifetime EP0221900B1 (en) 1984-06-15 1985-06-10 A method of breaking up bundles of adherent hard fibers and an oscillating screen

Country Status (7)

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EP (1) EP0221900B1 (en)
JP (1) JPS61502391A (en)
AU (1) AU4544085A (en)
DE (1) DE3579167D1 (en)
SE (1) SE447080B (en)
WO (1) WO1986000044A1 (en)
ZA (1) ZA854456B (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK164265C (en) * 1990-03-28 1992-11-02 Skako As METHOD OF DOSING FIBERS
EP0940168B1 (en) * 1998-03-06 2003-08-20 Excel Industries Limited Method and apparatus for the introduction of fibrous material into a substance
GB9804782D0 (en) * 1998-03-06 1998-04-29 Excel Ind Ltd Methods and apparatus for the introduction of fibrous material into a fibrous mixture
JP4695347B2 (en) * 2004-05-25 2011-06-08 光洋機械産業株式会社 Steel fiber supply equipment in raw concrete
JP2013255879A (en) * 2012-06-12 2013-12-26 Kureha Corp Method of sieving short carbon fiber, and the short carbon fiber
JP6902858B2 (en) * 2016-11-25 2021-07-14 株式会社Ｉｈｉ建材工業 Fiber disperser and concrete manufacturing equipment
JP6550430B2 (en) * 2017-09-01 2019-07-24 アルボルデマンサナ株式会社 Concrete mixing unit
JP7123328B1 (en) * 2021-12-24 2022-08-23 株式会社デーロス・ジャパン Apparatus for distributing short fibers for concrete reinforcement and method for distributing them
JP7083120B1 (en) * 2021-12-24 2022-06-10 株式会社デーロス・ジャパン Fiber reinforced concrete manufacturing equipment for narrow spaces and tunnel lining regeneration method under traffic operation using the equipment

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US724866A (en) * 1903-02-04 1903-04-07 Gustav J Holl Expanded-metal structure.
US2141400A (en) * 1936-01-11 1938-12-27 Cons Expanded Metal Companies Expanded metal product
GB1407035A (en) * 1972-07-22 1975-09-24 Caledonian Mining Co Ltd Apparatus for preparing and dispensing mixtures of concrete and fibres
DE2523905A1 (en) * 1975-05-30 1976-12-02 Joest Gmbh Schwingungstechnik Separating griddle for matted clumps of steel fibres - has vibrating sieve above storage box or concrete mixer

Also Published As

Publication number Publication date
JPS61502391A (en) 1986-10-23
ZA854456B (en) 1986-03-26
SE8403237D0 (en) 1984-06-15
WO1986000044A1 (en) 1986-01-03
AU4544085A (en) 1986-01-10
SE8403237L (en) 1985-12-16
DE3579167D1 (en) 1990-09-13
SE447080B (en) 1986-10-27
EP0221900A1 (en) 1987-05-20

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