Device for smoothing and for applying a treatment substance

Abstract

Device for smoothing a paper or board web ( 9 ) with at least one nip ( 6 ) formed between two rolls ( 3, 4 ), wherein at least one of the rolls ( 3 ) for controlling a thickness transverse profile of the paper or board web ( 9 ) in the web transverse direction is a deflection-adjustable and zone-controlled roll ( 3 ) for setting a line load distribution over the roll width which can be selected in the at least one nip ( 6 ), wherein the at least one nip ( 6 ) is provided for smoothing the thickness transverse profile of the paper or board web ( 9 ) by means of an adjustable line load profile and simultaneously introducing a treatment medium ( 2 ) into the paper or board web ( 9 ), for which purpose at least one coater ( 1 ) having a delivery nozzle ( 8 ) for applying application medium ( 2 ), in particular starch, is arranged in such a way that the application of the treatment medium ( 2 ) to at least one of the two rolls ( 3, 4 ) of the nip ( 6 ) is provided and is designed for indirect application of the treatment medium ( 2 ) to at least one side of the running paper or board web ( 9 ) and the at least one coater ( 1 ) has at least one delivery nozzle ( 8 ) with a device ( 13 ) for cross-profile adjustment of a volume flow of the treatment medium ( 2 ) which can be adjusted zone by zone over the web width.

1 . Device for smoothing a paper or board web, having at least one nip which is formed between two rolls, at least one of the rolls being a deflection-adjustable and zone-controlled roll for controlling a thickness transverse profile of the paper or board web in the web transverse direction in order to set a line load distribution over the roll width which can be selected in the at least one nip, wherein the at least one nip is provided for surfacing the thickness transverse profile of the paper or board web by means of an adjustable line load profile and simultaneously bringing a treatment substance into the paper or board web, for which purpose at least one coater having a delivery nozzle for applying a treatment substance, in particular starch, is arranged in such a way that the application of the treatment substance to at least one of the two rolls of the nip is provided and is designed for indirect applying of the treatment substance to at least one side of the running paper or board web and the at least one coater has at least one delivery nozzle with a device for cross-profile adjustment of a volume flow of the treatment substance which can be adjusted zone by zone over the web width. 
     
     
         2 . Device for smoothing according to  claim 1 , wherein the at least one deflection-adjustable and zone-controlled roll, by means of which the line load distribution in the at least one nip is controlled, is adjustable for calibrating the paper or board web in the transverse web direction. 
     
     
         3 . Device for smoothing according to  claim 1 , wherein the coater is a curtain application unit or a free jet application unit. 
     
     
         4 . Device for smoothing according to  claim 1 , wherein the at least one deflection-adjustable and zone-controlled roll is a hydrostatically supported roll with zone-by-zone control of elements along the width of the roll, each zone being designed to be controlled in groups or by individual elements. 
     
     
         5 . Device for smoothing according to  claim 1 , wherein sensor means are provided which scan and/or detect the paper or board web on one or both sides in the transverse direction of the web for adjusting the amount of pressure to be applied, depending on the surface quality and/or the thickness of the paper or board web in the transverse direction. 
     
     
         6 . Device for smoothing according to  claim 1 , wherein the cross-profile setting of the volume flow of the treatment substance, which can be set zone by zone over the web width, is controlled as a function of an area-related mass distribution of the paper or board web in the transverse direction of the web. 
     
     
         7 . Device for smoothing according to  claim 1 , wherein the consistency of a pulp suspension in the outlet of the headbox, which defines the basis weight produced, is selected as input variable for the amount of treatment substance supplied zone by zone in each case. 
     
     
         8 . Device for smoothing according to  claim 1 , wherein consistency sensors are provided with which a consistency transverse and longitudinal profile of a fibrous stock suspension in the outlet of the headbox can be measured in the resolution of an actuator division, which profile is selected as input variable of a control loop for the amount of treatment substance supplied zone by zone in each case. 
     
     
         9 . Device for smoothing according to  claim 1 , wherein the at least one nip is designed for line loads in a range from 20 to 200 kN/m. 
     
     
         10 . Device for smoothing according to  claim 1 , wherein the at least one nip is designed as a hard nip or soft nip. 
     
     
         11 . Device for smoothing according to  claim 1 , wherein the delivery nozzle comprises a plurality of slot nozzles each having an outlet slot with an accuracy in the range±2.5 μm to ±10 μm in slot length at a slot width of 100 to 2000 μm. 
     
     
         12 . Device for smoothing according to  claim 1 , wherein the space arrangement of the at least one coater relative to the nip is adjustable for an arrangement for indirect applying of the treatment substance and control of a dwell time of the treatment substance on the one of the two rolls ( 3 ,  4 ) which is simultaneously an applicator roll. 
     
     
         13 . Device for smoothing according to  claim 1 , wherein the coater is designed to control the solids content of the treatment substance in at least one layer from 6% to 55%. 
     
     
         14 . Device for smoothing according to  claim 1 , wherein the coater is designed to form a multilayer curtain. 
     
     
         15 . Device for smoothing according to  claim 1 , wherein zone widths of the profile adjustment at a slot nozzle of the delivery nozzle and/or the hydrostatically supported elements for profile correction are 50 to 300 mm, in particular 150 to 280 mm. 
     
     
         16 . Device for smoothing according to  claim 1 , wherein at least one roller of the at least one nip is designed as a heatable applicator roller and is designed for a temperature of the roller surface of 60° C. to 160° C. 
     
     
         17 . Device for smoothing according to  claim 1 , wherein the rolls of the at least one nip have coatings with less than 30 P&J. 
     
     
         18 . Device for smoothing according to  claim 1 , wherein an angle α for an impact point of the treatment substance on an application roller of the press nip is between −90° and +45°. 
     
     
         19 . Device for smoothing according to  claim 1 , wherein the adjustable line load distribution and the adjustable quantitative application of treatment substance can be matched to one another by means of a control system in such a way that a compacted paper or compacted board with a leveled surface having selectable strength properties (CMT, SCT, RCT) in the transverse direction of the web can be produced. 
     
     
         20 . Device for smoothing according to  claim 1 , wherein a volume flow profile at the coater is adjustable by offline measurement of paper/board web samples.