Classifications

• • 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
  • D21D5/16—Cylinders and plates for screens
• • 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
  • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
  • B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
  • B07B1/4618—Manufacturing of screening surfaces
• • 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
  • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
  • B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
  • B07B1/4663—Multi-layer screening surfaces
• • 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
  • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
  • B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
  • B07B1/469—Perforated sheet-like material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/18—Filters characterised by the openings or pores
  • B01D2201/184—Special form, dimension of the openings, pores of the filtering elements
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining

Definitions

• the invention relates to a method for producing a screen according to the preamble of claim 1.
• Sieves made in a process according to the invention are preferably used for wet screening of pulp suspensions to remove contaminants present therein.
• they are rigid and differ from flexible endless screens used in screen presses and paper machines.
• the characteristic of such a sieve results essentially from the size, shape and number of openings located therein. These are usually kept smaller than the researchsiebenden substances.
• Such screens are advantageously used e.g. in pulpers, secondary pulpers and sorters for the treatment of paper fiber suspensions, where they have the task of retaining impurities.
• such screens should have a sorting characteristic, e.g. through round openings between 1 and 30 mm, depending on the coarseness of the materials, is achievable.
• the invention is based on the object to provide a method for the production of sieve elements, which, measured by the utility value of the sieve element, is relatively inexpensive and ensures an optimum sorting characteristic, in particular in the sorting of pulp suspensions.
• Sieves which are to be used for the treatment of pulp suspensions, must have a sufficient wall thickness (thickness) for strength reasons.
• the special design of the sieve openings seen over the course in the sieve, can be selected in the selection of a larger number of sieve layers, that is more than 3, e.g. 6 to 8 sieve layers, perform very well.
• the individual screen layers consist of thin sheets (e.g., 2 mm) which are apertured by punching, laser cutting, or other methods.
• the screen layers are e.g. made of metal, plastic, rigid foam or natural building materials.
• a combination of different materials is advantageous, e.g. particularly abrasion-resistant material in the inlet-side screening layer (upper layer) and particularly tough material in the middle layers and / or the lower layer.
• the sieve produced by the process is provided with blind holes, which of course can be achieved without much effort by the new manufacturing process by no opening is at certain points of the corresponding sieve layer.
• connection of the mesh layers with each other solvable, in order to have the ability to easily replace worn parts.
• Detachable compounds are e.g. formed by screws, rivets, clamps or positive locking, just to name these.
• these can be connected to each other in a partially releasable and partly inseparable manner, which offers the possibility of providing only the inlet-side layer (upper layer) which is particularly exposed to wear for replacement.
• the feed-side sieve layer (upper layer), which is crucial for the sieve characteristic, can be kept relatively thin, yet a sieve of high strength is produced by a correspondingly robust further layer or further layers.
• the possibility of being able to use a thin top layer also has the advantage of a lower pressure drop during operation, since only short flow paths are formed in the finished sieve within the openings of the top layer which determine the sieve character. The length of this flow path corresponds to the thickness of the upper layer. Although a conical expansion of the screen openings in the intended flow direction is required, the production is still easier than one-piece screens.
• the process serves to produce flat screens.
• a sieve may have the shape of a circular ring, which may be composed of circular ring segments.
• a screen is produced as a cylindrical screen basket in which the inlet-side screen layer is radially inward and further layers are on the outside, the inlet-side layer can be provided with the openings in the flat state. If it is then bent, as a result of the bend, the openings, viewed radially, expand from the inside to the outside. So arise by special Manufacturing process in the sorting layer conical openings by expanding the flow cross sections.
• Fig. 1 A part of a sieve produced by the method, shown in section; Fig. 2-6 different variants using the example of different screens, shown in section; Fig. 7-8 each produced by the process screen member in view of the
• Fig. 9 is a produced by the process sieve with rings of different
• FIG. 1 shows by way of a first example a screen 1 produced by the process according to the invention.
• This consists of the three surface-connected screen layers 2, 3 and 4 and screen openings 7 and 8, respectively, which pass through all the screen layers in this example.
• the screen layers are connected to each other at the contact surfaces 17, e.g. by high temperature soldering.
• the top screen 2 forms the inlet side, i. that the liquid to be filtered flows from top to bottom through the openings 7 and 8, respectively. It is seen in this flow direction of the screen, the downstream opening is larger than the respective upstream opening. That in the direction of flow of the screen, the cross sections are larger at certain points, resulting in a particularly good blockage freedom of the screen.
• the screen openings 8 drawn to the right are essentially cylindrical
• the screen openings 7 drawn on the left are composed of a combination of two cylinders and in an intermediate conical opening (screen layer 3). Even if the openings 7 and 8 are shown here in the same sieve, this is to be regarded as an exception. Usually the screen openings are equal to each other. The same applies to the other figures.
• the smallest openings on the feed side of the screen 1 ie here in the uppermost screen layer 2 compared with those in downstream screen layers. These smallest openings determine the separation characteristic, ie which parts pass through the sieve or are rejected in front of it.
• the invention it is easily possible to set not only the size, but also the shape of the smallest opening to the requirements. Such shapes can be, for example, circles, ovals, slots, rectangles, or polygons, to name just a few.
• a suitably favorably selected shape and arrangement (“screen pattern”) can be a large free area, based on the entire screen surface produce.
• the four-layered screen shown in FIG. 2 has, in the middle layers 3 and 4, oblique and in the bottom of the screened layer 5 cylindrical openings which have a lateral offset with respect to the upstream openings.
• Such a shape of the screen openings can be realized relatively easily with the aid of the method according to the invention and has the advantage that a better flow rate is possible in the case of an oblique approach to the liquid to be screened.
• the oblique flow is due to the fact that an oblique velocity direction is generated with the aid of a screen sweeper 14 (clearing rotor) moving past the screen (in the direction of the arrow), which is thus not perpendicular to the screen plane.
• the flow can impinge obliquely.
• a sieve is shown with a total of five layers, the openings 10 are made slightly conical in several cases.
• the conicity can come from the punching process, ie the introduction of the openings in the screen layers, which is known to cause the side walls are not parallel to each other, but at an acute angle. This taper is exaggerated in FIG.
• the method according to the invention also makes it very easy to provide a screen with discontinuous recesses 11, as shown in Fig. 4.
• a recess 1 1 results from the fact that the respective opening does not extend through all layers of mesh, but for example only through the inlet-side screen layer 2. It may be, for example, round or groove-shaped.
• Fig. 4 shows a strip-shaped projection, the is formed by the inclusion of a profile bar 12. This is in a matching recess, which passes through one or more screen layers (here, for example, 2 + 3) used, for example, soldered.
• Recesses or projections on the inlet side of the screen are suitable for influencing the flow of the liquid to be screened in such a way that the clogging tendency of the adjacent screen openings decreases.
• inserts 13 which have continuous screen openings 15 in their middle and are inserted into several or all screen layers 2, 3, 4.
• Such inserts 13 can be made particularly wear-resistant and may be interchangeable (see Fig. 5).
• inserts 13 with suitable sieve openings 15 are shown in Fig. 6.
• m is suitably between 0.5 and 5 mm.
• the insert 13 ' shown in the center of this Fig. 6 does not extend through all screen layers, but only through the upper screen layers 2 and 3. In this way, the wear-prone parts of the screen, so the inserts 13 ' , are kept smaller.
• the wear in the area is particularly high, where the Sieb thriftr 14 is used.
• the represented shape of the insert 13 ' extending over two sieve layers is particularly easy to replace, if it is ensured that the two sieve layers 2 and 3 can be separated without destroying them. This also applies to operations without supernatant.
• FIG. 7 shows a view of the outflow side of a screen produced according to the invention.
• This is a partial view, which in total consists of three screen layers 2, 3, 4, between which the contact surfaces 17 are located.
• the screen openings 8 shown on the left each have a cylindrical cross-section whose diameter is different in the different screen layers.
• the openings in the individual screen layers are offset from each other, so that there is an oblique flow direction.
• a similar offset also has the sieve opening 16, whose flow cross-section has the shape of a slot.
• a further advantage of the production method according to the invention lies in the possibility that at least one screen layer, in particular the inlet-side screen layer 2, is divided into a plurality of preferably concentric circular rings 18, 19 and that these circular rings 18, 19 are made of different material (FIG. 9).
• a radially outer sieve ring 19 may then be e.g. consist of a particularly high-quality wear-resistant material, while the radially inner sieve ring 18 can be made correspondingly cheaper, with the advantage that despite reduced manufacturing costs, the wear behavior of the entire sieve 1 is not worse.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Paper (AREA)
• Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
• Combined Means For Separation Of Solids (AREA)
• Filtering Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

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Family Applications Before (1)

Country Status (8)

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• 2007
  • 2007-04-30 DE DE102007020325A patent/DE102007020325B3/de not_active Expired - Fee Related
• 2008
  • 2008-01-08 EP EP10175598A patent/EP2290160A1/de not_active Withdrawn
  • 2008-01-08 JP JP2010504586A patent/JP2010525185A/ja not_active Ceased
  • 2008-01-08 CN CN200880014155A patent/CN101675192A/zh active Pending
  • 2008-01-08 WO PCT/EP2008/050128 patent/WO2008131974A1/de active Application Filing
  • 2008-01-08 KR KR1020097022805A patent/KR20100016106A/ko not_active Application Discontinuation
  • 2008-01-08 EP EP08701301A patent/EP2152961A1/de not_active Withdrawn
  • 2008-02-11 JP JP2010504587A patent/JP2010525186A/ja active Pending
  • 2008-02-11 BR BRPI0811018-2A2A patent/BRPI0811018A2/pt not_active IP Right Cessation
• 2009
  • 2009-10-29 US US12/608,133 patent/US20100059487A1/en not_active Abandoned
  • 2009-10-29 US US12/608,141 patent/US8123912B2/en not_active Expired - Fee Related
• 2011
  • 2011-10-13 US US13/272,962 patent/US8216428B2/en not_active Expired - Fee Related

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