EP0371786A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Web forming method and apparatus
Assignee: Valmet Technologies Oy
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Filing: 1989-11-29
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Granted: —
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Expires: 2009-11-29
Abstract
Abstract A method for forming a paper or paperboard web from a fibrous material in the wire section of a paper making machine or equivalent machine comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop; wherein in the method fibre slurry coming out of the headbox (1;101) of the paper making machine is fed to the first part (2a; 102a) of the top run of said bottom wire loop (2;102), which forms the first dewatering zone after which the partly formed fibre layer is led to the second dewatering zone, in the area of which said top wire loop (10;110) moves to cover said partly formed fibre layer in such a way that water removal from the fibre layer continues it least in two stages in the area of said second dewaterlng zone, whereupon the top wire loop (10;110) is separated from the nearly formed web (W) that is led to follow the run of the bottom wire loop (2;102) forward to the next processing stages of the web (W), wherein the method is characterized in that in the single-wired dewatering zone (2a;102a), after the initial water removal is carried out through the bottom wire (2;102), water removal through the bottom wire (2;102) is prevented by means of an element group (9; 109) operating in contact with the inner surface of the horizontal top run of the bottom wires; that in said water-removal prevention area water is removed from the web (W) through the top wire in the first stage or stages of the double-wired second dewatering zone, which stages comprise a relatively long, planar wire table extending from the headbox to the forming roll (6 in Fig. 1), or from the headbox to the last supporting element (109 in Fig. 2); and that after the first dewatering stage or stages of the double-wired zone water is removed in a curved double-wired dewatering zone (b) (Fig. 1) or zones (R o , C) (Fig. 2), after which the web (W) is led to follow the bottom wire (2;102).
Inventors
- 👤 Tapio Waris
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 02:51
CPC Classifications
D; D21; D21F; D21F1/00; D21F3/00; D21F1/48; D21F9/00; D21F9/003
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
360 words
A method for forming a paper or paperboard web from a fibrous material in the wire section of a paper making machine or equivalent machine comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop; wherein in the method fibre slurry coming out of the headbox (1;101) of the paper making machine is fed to the first part (2a;102a) of the top run of said bottom wire loop (2;102), which forms the first dewatering zone after which the partly formed fibre layer is led to the second dewatering zone, in the area of which said top wire loop (10;110) moves to cover said partly formed fibre layer in such a way that water removal from the fibre layer continues at least in two stages in the area of said second dewatering zone, whereupon the top wire loop (10;110) is separated from the nearly formed web (W) that is led to follow the run of the bottom wire loop (2;102) forward to the next processing stages of the web (W), wherein the method is characterized in that in the single-wired dewatering zone (2a;102a), after the initial water removal is carried out through the bottom wire (2;102), water removal through the bottom wire (2;102) is prevented by means of an element group (9; 109) operating in contact with the inner surface of the horizontal top run of the bottom wires; that in said water-removal prevention area water is removed from the web (W) through the top wire in the first stage or stages of the double-wired second dewatering zone, which stages comprise a relatively long, planar wire table extending from the headbox to the forming roll (6 in Fig. 1), or from the headbox to the last supporting element (109 in Fig. 2); and that after the first dewatering stage or stages of the double-wired zone water is removed in a curved double-wired dewatering zone (b) (Fig. 1) or zones (R o , C) (Fig. 2), after which the web (W) is led to follow the bottom wire (2;102).
Claim 2
Independent Claim
360 words
A method for forming a paper or paperboard web from a fibrous material in the wire section of a paper making machine or equivalent machine comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop; wherein in the method fibre slurry coming out of the headbox (1;101) of the paper making machine is fed to the first part (2a;102a) of the top run of said bottom wire loop (2;102), which forms the first dewatering zone after which the partly formed fibre layer is led to the second dewatering zone, in the area of which said top wire loop (10;110) moves to cover said partly formed fibre layer in such a way that water removal from the fibre layer continues at least in two stages in the area of said second dewatering zone, whereupon the top wire loop (10;110) is separated from the nearly formed web (W) that is led to follow the run of the bottom wire loop (2;102) forward to the next processing stages of the web (W), wherein the method is characterized in that in the single-wired dewatering zone (2a;102a), after the initial water removal is carried out through the bottom wire (2;102), water removal through the bottom wire (2;102) is prevented by means of an element group (9; 109) operating in contact with the inner surface of the horizontal top run of the bottom wires; that in said water-removal prevention area water is removed from the web (W) through the top wire in the first stage or stages of the double-wired second dewatering zone, which stages comprise a relatively long, planar wire table extending from the headbox to the forming roll (6 in Fig. 1), or from the headbox to the last supporting element (109 in Fig. 2); and that after the first dewatering stage or stages of the double-wired zone water is removed in a curved double-wired dewatering zone (b) (Fig. 1) or zones (R o , C) (Fig. 2), after which the web (W) is led to follow the bottom wire (2;102).
Claim 3
Dependent Claim
85 words
A method according to claim 1, characterized in that the double-wired second dewatering zone is divided into at least two successive stages, where in the area of the first or two first stages water removal is prevented through the bottom wire (2,102) by means of self-adjusting supporting elements (9;109) placed in the plane (T-T) of the single-wired first part (2a;102a); that water removal close to said supporting elements (9;109) is performed through the top wire assisted by the suction and/or foil elements (21, 21′, 21˝).
Claim 4
Dependent Claim
53 words
A method according to claim 2, characterized in that the last water removal stage to be carried out between the two wires (2, 102, 10, 110) takes place in the double-wired zone (b,c) which curves downwards and is guided by the forming roll (6, 106) located inside the bottom wire loop (Fig. 1).
Claim 5
Dependent Claim
64 words
A method according to claim 3, characterized in that after the first water-removal preventing stage or stages of the double-wired zone said double-wired zone is led to curve (R o ) upwards by the action of the guiding elements located inside the top wire loop (110), after which the double-wired zone is led to curve downwards guided by the forming roll (106) or equivalent.
Claim 6
Independent Claim
61 words
A method according to any of claims 1-4, characterized in that the method applies a relatively short single-wired dewatering zone (2a;102a), in the area of which water is removed to such extent that the dry content of the web (W) before the double-wired dewatering zone is in the range of 1-4 per cent, the most suitable range being 2-3 per cent.
Claim 7
Dependent Claim
196 words
A web forming apparatus for carrying out a method according to any of claims 1-5, comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop, as well as a headbox (1;101) that is arranged to feed a jet (J) of fibre slurry to the single-wired first part (2a;102a) of the top run of the bottom wire loop, after which there is a double-wired forming zone that is limited between the common travels of the bottom wire (2;102) and the top wire (10, 110), and in which forming zone, inside the bottom wire loop, there are different elements and element groups (9, 6, 8 or 109, 106, 108) and inside the top wire loop respectively there are elements (12 or 112) affecting the water removal, characterized in that the double-wired second dewatering zone extends over a relatively long first planar part and as an immediate extension of the single-wired first part (2a;102a) of the wire table, and after which the double-wired zone curves over the guiding surface of the stationary and/or rotary guiding element.
Claim 8
Dependent Claim
85 words
An apparatus according to claim 6, characterized in that in said planar first stage of the double-wired dewatering zone there are devices for both water removal and water removal prevention located on the opposite sides of the wires and cooperating with another, comprising the self-adjusting supporting elements (9;109) of the bottom wire, located inside the bottom wire loop and arranged also to work as water-removal prevention members, and the suction chamber and foil elements (12;112) placed in the opposite location inside the top wire loop.
Claim 9
Dependent Claim
59 words
An apparatus according to claim 6 or 7, characterized in that the self-adjusting cross members or beams supported by the loading hoses or equivalent act as preventing members of water removal; the cross members or beams extending over two or three suction chambers (16, 17, 18) and over the foils (21, 21′, 21˝) controlling the top wire (10, 110).
Claim 10
Dependent Claim
77 words
An apparatus according to claim 8, characterized in that in connection with the front wall of the dewatering device (12,112) located inside the top wire loop (10,110) there is an auto-slice arrangement and a suction channel (16a) which is directed upwards and opens into the first suction chamber (16); and that on the inlet of said suction chamber (16a) there is a blade (22) which possibly is adjustable in height level by a device (23) (Fig. 4A).
Claim 11
Independent Claim
62 words
An apparatus according to any of claims 6-8, characterized in that the inlet part of the auto-slice channel (16a) of the first suction chamber (16) of the dewatering device (112) inside the top wire loop (10) is on its top side limited by a rotating variable speed roll (22A), the position of which can be arranged adjustable in vertical direction (Fig. 4B).
Claim 12
Independent Claim
84 words
An apparatus according to any of claims 6-10, characterized in that in the area of the last chamber (118) of the dewatering device (112) located inside the top wire loop (110) the double-wired zone is arranged to curve upwards guided by foil blades or equivalent stationary elements (Fig. 3B), after which the double-wired zone is arranged to curve downwards on the surface of a forming roll (106) or equivalent and to return to the level (T-T) of the single-wired first part (102a) (Fig. 2).
Claim 13
Independent Claim
128 words
An apparatus according to any of claims 6-10, characterized in that the dewatering device (12) inside the top wire loop (10) comprises a unit that is provided with minimum two, preferably three successive suction chambers (16, 17, 18) with the foil blades (21, 21′, 21˝) on the bottom part arranged to control the double-wired dewatering zone as an extension to the single-wired first part (21, 102); that there is a supporting beam arrangement (9) under said planar portion; and that after said dewatering device (12) the double-wired zone bends downwards over a forming roll (6) or an equivalent stationary sector (b), after which there is a planar suction box (8) inside the bottom wire loop (2) ensuring that the web (W) follows the bottom wire (2) (Fig. 1).
References Cited (Backward Citations)
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