EP0357382A2 - Tamis cylindrique et son procédé de fabrication - Google Patents

Tamis cylindrique et son procédé de fabrication Download PDF

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Publication number
EP0357382A2
EP0357382A2 EP89308735A EP89308735A EP0357382A2 EP 0357382 A2 EP0357382 A2 EP 0357382A2 EP 89308735 A EP89308735 A EP 89308735A EP 89308735 A EP89308735 A EP 89308735A EP 0357382 A2 EP0357382 A2 EP 0357382A2
Authority
EP
European Patent Office
Prior art keywords
screen cylinder
cylinder
screen
tool
rings
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.)
Withdrawn
Application number
EP89308735A
Other languages
German (de)
English (en)
Other versions
EP0357382A3 (fr
Inventor
Jouko Lassila
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.)
Ahlstrom Corp
Original Assignee
Ahlstrom Corp
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 Ahlstrom Corp filed Critical Ahlstrom Corp
Publication of EP0357382A2 publication Critical patent/EP0357382A2/fr
Publication of EP0357382A3 publication Critical patent/EP0357382A3/fr
Withdrawn legal-status Critical Current

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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

Definitions

  • the present invention relates to a screen cylinder and especially to a method of manufacturing thereof.
  • the screen cylinder manufactured by the method according to the invention is especially suitable for screening fiber suspensions of the pulp and paper industry.
  • US patent specification 2,850,165 discloses a screen cylinder comprising a great number of axial rods with screening slots therebetween, both ends of said rods being supported in grooves, thereby enabling adjusting of the distance between the rods, i.e. the slot width.
  • the radial support is secured by arranging a few clamping rings equally spaced inwardly from said rods, against which rings the rods are clamped by means of strips outside the rods.
  • the manufacturing process of such screen cylinders is very slow and complicated and consequently also expensive. Furthermore, the complicated support structure makes them unnecessarily heavy and their strength does not meet today's requirements.
  • DE patent application 30 15 370 discloses a structure of a screen drum assembled by piling a great number of rings, made by winding a wire of a certain cross-sectional shape, on top of each other leaving a slot of a certain dimension therebetween, said slot being formed by intermediate members and being relatively easy to adjust to a desired dimension with said intermediate members.
  • the manufacture of the drum is, however, not even in this case very simple because the drum is composed of a great number of separate parts, which have to be assembled and fixed together tightly.
  • the prior art also includes a number of screen cylinder arrangements, in which the screen surface itself is a flat plate, which is expediently bent to form the screen cylinder.
  • the most common way of manufacturing screen plates and cylinders therefrom is such that the plate is perforated and finished to the maximum prior to bending thereof, whereby it is easy to give the desired direction and shape to the perforations or slots to be machined unless the deformations caused by bending of the plate are counted. Hitherto, it was common to assemble a screen cylinder from a number of relatively small, bowed pieces of plate. In such cases, a separate screen body was usually needed to which the bowed pieces of plate were attached by welding, riveting or by some other appropriate manner.
  • the screen drum is composed of only one plate, which most usually is ready machined in the form of a plate, then bent to a cylindrical shape and the edges welded together into a form of a drum.
  • the screen surfaces should be as thin as possible, which results in the strength of the drum being not adequate and the drum has to be provided with reinforcements.
  • a corresponding screen drum is also disclosed in US patent specification 4,264,438, in which the drum comprises at least two cylindrical screening sections, with a stiffening ring, and more specifically a flange-like protrusion of the stiffening ring therebetween, said cylindrical screening sections being welded to said stiffening ring, nowadays with either MIG or TIG welding method.
  • attachment by welding especially with the above-mentioned welding methods, has drawbacks because the heat transferring to the piece during welding causes deformations and consequently, the finished cylinder in most cases has to go through a finishing-up treatment, where in most cases the rings thereof are turned and polished to their final dimensions.
  • the stiffening rings have to be supported well in place and be bridged separately prior to actual tacking.
  • the object of the invention is especially to rationalize the manufacture of screen cylinders in such a way that the end rings and clamping rings of the screen cylinder can be attached to the cylinder exactly where desired without prior bridging or setting, and also be fixed reliably without a risk of deformation of the cylinder due to excessive heat transfer.
  • the latter problem has been solved by taking laser welding into use.
  • the heat amount transferring through the weld seam to the piece being welded only ranges from a fifth to a tenth of the heat amount transferring in the MIG and TIG welding.
  • the laser welding brings about a problem to the existing method of manufacture.
  • the method and apparatus according to the present invention has been developed to eliminate or minimize the drawbacks described above and to optimize the manufacture of screen cylinders.
  • the method according to the invention is characterized in that the exact disposition of the clamping rings on the cylinder surface is secured by assembling the cylinder of several cylindrical sections wherebetween the clamping rings are inserted.
  • the wear of the cylinder material can be better controlled because the cylinder is assembled of smaller cylindrical sections and, on the other hand, the clamping rings are disposed exactly in place at once, not being necessary to be separately bridged in place prior to final welding, which was compulsory when the claimping rings were fixed around a finished, plain cylinder or alternatively inside thereof.
  • the laser welding gives a higher manufacturing accuracy than the earlier methods because, firstly, the heat transferring to the piece during welding does not deform the piece and, secondly, the laser itself requires a high accuracy in alignment of the pieces to be welded.
  • the width of the air slot between the pieces shall be 0.2 mm at most, otherwise the pieces are not hit by the laser beam at all.
  • the disposition accuracy of the laser is about 0.3 mm.
  • a still further advantage achieved by the present invention is that the screen cylinder can be assembled of sections that have been ready machined to the final surface quality and dimensional accuracy, whereby the ordinary procedure of finishing-up machining after welding can be avoided.
  • the method of the invention is further characterized in that the screen cylinder is assembled by arranging cylindrical screening sections and clamping rings one after another in turn and by providing the cylinder ends with end rings as to receive a desired length of the screen cylinder, whereafter the parts of the screen cylinder are compressed and welded together in one working stage.
  • a tool used in the method of the invention is characterized in that it comprises a piece provided with a surface of substantially rotational symmetry, said surface being arranged with steps whereupon the end ring of the screen cylinder lies during the manufacture of said screen cylinder.
  • a preferred embodiment of the screen cylinder manufactured by the method according to the invention is characterized in that the height of the flange of the clamping ring substantially equals the thickness of the screen plate.
  • a screen cylinder 1 manufactured by the method of the invention comprises a plurality of cylindrical sections 2 - 4 disposed one after another, the screening openings 6 of which may be either similar to or different from one another.
  • the method according to the invention it is possible either to fix clamping rings 7 of the screen cylinder simply and reliably between cylindrical sections similar to each other or to unite, by means of said clamping rings, cylindrical sections that are different from each other as to their contour or perforation.
  • the method of the invention enables accurate and simple attachment of the end rings 8 and 9 within the area of the ends of the screen cylinder 1.
  • Fig. 2 illustrates some preferred embodiments for manufacturing a screen cylinder by uniting the cylindrical sections 3 and 4 with a clamping ring 7.
  • the clamping ring shown in Fig. 2 a more or less corresponds to the embodiment disclosed in US patent 4,264,438, where welding may be effected from either the flange 10 of the clamping ring 7, the height of which flange, unlike in said US patent, substantially corresponds to the thickness of the screen plate, to the end levels of the cylindrical sections 3 and 4 or from the clamping ring itself to the sides of the end faces of the cylindrical sections.
  • Fig. 2 b illustrates an embodiment in which the flange 10 of the clamping ring 7 is lower than the thickness of the screen plate. Consequently, the clamping ring can be welded on from either the slot between the cylindrical sections 3 and 4, whereby the cylindrical sections will also be welded together, or from the clamping ring itself to the sides of the end faces of the cylindrical sections.
  • Fig. 2 c illustrates a further embodiment, in which the cross section of the flange 10 of the clamping ring 7 is triangular, whereby the end faces of the cylindrical sections 3 and 4 need only to be bevelled correspondingly to ensure a good fit. Fixing is effected as in the embodiment of Fig. 2 b. It is also noteworthy that the clamping rings described above are applicable both inside and outside of the drum.
  • Fig. 3 illustrates various alternatives of disposing the end rings of the screen cylinder.
  • a corner of the end ring 8 is provided with a notch 11 for the screen cylinder 1, said notch abutting against the cylinder both axially and radially.
  • the end of the cylinder 1 has a notch 12 and the end ring has a corresponding flange 13, whereby both axial and radial support are provided.
  • a side of an end face of the cylinder 1 has a cut-out 12, in which the end ring 8 is disposed.
  • both axial and radial support is provided.
  • Fig. 4 illustrates a tool 15, by which the cylinder is compressed from the opposite ends thereof.
  • the tool 15 mainly comprises a tapered piece, the tapered surface of which is provided with steps.
  • the piece is axially rotatable for welding.
  • the steps of the tool sum to a diameter of three millimeters so that, with three pairs of tools, it is possible to fabricate a series of cylinders the diameters of which grow by one millimeter step by step.
  • the end section of the screen cylinder according to the embodiment of Fig. 3 a is shown by a dash line. It can be seen that the cylinder is supported at its end ring by a tool, whereby locking into a fixed form is provided already at the end rings.
  • the clamping rings are also disposed according to corresponding lockings into fixed forms respective to the cylindrical screening sections.
  • the screen cylinder is so fabricated that on top of the tool is disposed an end ring of the desired dimension, said end ring matching the step of the tool exactly.
  • Onto the end ring there is disposed a desired number of cylindrical sections and clamping rings one on top of the other in turn, and when the cylinder length meets the requirement, the other end of the cylinder will also be provided with an end ring and a tool on top thereof.
  • the tools are tightened towards one another, a laser welding device is focused on its starting point, and the assembly welding of the screen cylinder will be effected automatically.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
EP19890308735 1988-08-31 1989-08-30 Tamis cylindrique et son procédé de fabrication Withdrawn EP0357382A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI884001 1988-08-31
FI884001A FI80916C (fi) 1988-08-31 1988-08-31 Siltrumma och foerfarande foer framstaellning daerav.

Publications (2)

Publication Number Publication Date
EP0357382A2 true EP0357382A2 (fr) 1990-03-07
EP0357382A3 EP0357382A3 (fr) 1990-11-22

Family

ID=8526978

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890308735 Withdrawn EP0357382A3 (fr) 1988-08-31 1989-08-30 Tamis cylindrique et son procédé de fabrication

Country Status (2)

Country Link
EP (1) EP0357382A3 (fr)
FI (1) FI80916C (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997034045A1 (fr) * 1996-03-11 1997-09-18 Beloit Technologies, Inc. Cylindre d'epurateur de pate a papier
WO1998006893A1 (fr) * 1996-08-09 1998-02-19 Sunds Defibrator Industries Ab Panneau de criblage et son procede de fabrication
WO1999024663A1 (fr) * 1997-11-07 1999-05-20 Valmet Fibertech Ab Platine d'epuration
EP1273696A1 (fr) * 2001-07-05 2003-01-08 Aikawa Iron Works Co., Ltd. Tamis cylindrique
US7506767B2 (en) 2003-08-22 2009-03-24 Metso Paper, Inc. Method for manufacturing screen cylinder and screen cylinder
CN105339545B (zh) * 2013-07-01 2017-10-13 安德里兹·菲德勒有限责任公司 筛分装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI57986C (fi) * 1979-02-28 1980-11-10 Ahlstroem Oy Siltrumma och saett att tillverka denna

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997034045A1 (fr) * 1996-03-11 1997-09-18 Beloit Technologies, Inc. Cylindre d'epurateur de pate a papier
US5791495A (en) * 1996-03-11 1998-08-11 Beloit Technologies, Inc. Paper pulp screen cylinder
WO1998006893A1 (fr) * 1996-08-09 1998-02-19 Sunds Defibrator Industries Ab Panneau de criblage et son procede de fabrication
US6216877B1 (en) 1996-08-09 2001-04-17 Valmet Fibertech Aktiebolag Screen panel and method of its manufacture
WO1999024663A1 (fr) * 1997-11-07 1999-05-20 Valmet Fibertech Ab Platine d'epuration
US6257413B1 (en) 1997-11-07 2001-07-10 Valmet Fibertech Ab Screen panel
EP1273696A1 (fr) * 2001-07-05 2003-01-08 Aikawa Iron Works Co., Ltd. Tamis cylindrique
US7506767B2 (en) 2003-08-22 2009-03-24 Metso Paper, Inc. Method for manufacturing screen cylinder and screen cylinder
CN105339545B (zh) * 2013-07-01 2017-10-13 安德里兹·菲德勒有限责任公司 筛分装置

Also Published As

Publication number Publication date
EP0357382A3 (fr) 1990-11-22
FI80916C (fi) 1990-08-10
FI884001A7 (fi) 1990-03-01
FI884001A0 (fi) 1988-08-31
FI80916B (fi) 1990-04-30

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