(19)
(11) EP 0 357 382 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.11.1990 Bulletin 1990/47

(43) Date of publication A2:
07.03.1990 Bulletin 1990/10

(21) Application number: 89308735.3

(22) Date of filing: 30.08.1989
(51) International Patent Classification (IPC)5: D21D 5/16
(84) Designated Contracting States:
AT DE FR GB SE

(30) Priority: 31.08.1988 FI 884001

(71) Applicant: A. AHLSTROM CORPORATION
29600 Noormarkku (FI)

(72) Inventor:
  • Lassila, Jouko
    SF-02270 Espoo (FI)

(74) Representative: Gilmour, David Cedric Franklyn et al
POTTS, KERR & CO. 15 Hamilton Square
Birkenhead Merseyside L41 6BR
Birkenhead Merseyside L41 6BR (GB)


(56) References cited: : 
   
       


    (54) Screen cylinder and method of manufacture


    (57) The present invention relates to a screen cylinder (1) and a method of manufacturing thereof. The method and the screen cylinder according to the invention are especially suitable for treating fiber suspensions of the pulp and paper industry.
    Screen plates of the prior art are mainly manufactured by manual welding, whereby the dimensional accuracy of the cylinders has been low and, because of the welding method used, the cylinder has had to be finish machined after assembly.
    The method of the invention is characterized in that the screen cylinder (1) is assembled into a single package comprising cylindrical screening sections (2-4), clamping rings (7) and end rings (8,9), which are ready finished as to their dimensional accuracy and surface quality, said parts being then compressed by means of a special tool and welded together, preferably by a laser welding method, in one working stage.







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