METHOD AND DEVICE IN THE PRESS SECTION OF A PAPER MACHINE FOR THE CONTROL OF THE NIP-PRESSURE PROFILE

摘要

A method and apparatus in the press section of a papermachine for regulating the axial linear-load profiles in its nip ornips (N1,N2,N3). The axial temperature profile(s) of the outermantle(s) of a press roll or rolls (11, 13, 16, 17) is/areregulated. Thereby, the distribution of the diameter of the pressroll in the axial direction is controlled on the basis of thermalexpansion. Also thereby, the distribution in the transversedirection of the machine of the linear load in the press nip or nips(N1,N2,N3) formed by the press roll or rolls (11, 13, 16, 17)is affected. The temperature profile of the outer mantle(s) (11',13', 17') of the press roll or rolls (11, 13, 17) is regulated by apress felt or felts (10, 14, 18) running through the press nip ornips (N1, N2, N3) formed by the roll applying a heating/coolingeffect whose profile in the axial direction of the roll is regulated,and/or by applying a set of water jets (F) directly onto the outermantle(s) of the press roll or rolls, the jets' quantity distribution(Fl...FN) and/or temperature distribution (Tl...TN) beingregulated so as to obtain the desired distribution of nip-pressureprofile.