EP0432571A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Suction roll for a paper machine and a method for producing a desired pressure profile for a suction roll
Assignee: Valmet Technologies Oy
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Filing: 1990-11-27
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Granted: —
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Expires: 2010-11-27
Abstract
Abstract The invention concerns a suction roll (10) for a paper machine, on which the paper web is pressed towards the outer face of the roll mantle. The suction roll (10) is divided, in the axial direction of the roll, into at least three vacuum spaces (A1,A2,A3). In the interior of the suction roll (10), there are at least two partition walls (17a,17b), by means of which the suction space (13) is divided into separate zones of negative pressure. The lateral vacuum spaces (A1,A3) in the suction space can be subjected to a higher negative pressure than the vacuum space (A2) in the middle area of the roll, whereby the profile of negative pressure is formed such that the negative pressure increases across the width of the roll towards the lateral areas. The invention also concerns a method for producing a desired pressure profile for a suction roll. <IMAGE>
Inventors
- 👤 Jouko Aula
- 👤 Heikki Ilvespää
- 👤 Allan Liedes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 06:41
CPC Classifications
D; D21; D21F; D21F3/00; D21F3/02; D21F3/10; D21F5/00; D21F5/02; D21F5/04; D21F5/042
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
220 words
Suction roll (10) for a paper machine, comprising a perforated roll mantle (11), a suction space (13) inside the roll mantle (11), which suction space can be subjected to negative pressure, the air flow passing through the perforations in the roll into the interior of the roll and the paper web (W) being pressed towards the outer face of the roll mantle (11), characterized in that the suction roll (10) is divided in the direction of width of the roll into at least three vacuum spaces (A₁,A₂,A₃), while the suction roll (10) comprises at least two partition walls (17a,17b) In the interior of the roll, by means of which said partition walls the suction space (13) is divided into separate zones of negative pressure, whereby the lateral vacuum spaces (A₁,A₃) in the suction space can be subjected to a higher negative pressure than the vacuum space (A₂) in the middle area of the roll, whereby the profile of negative pressure is formed such that the negative pressure increases across the width of the roll towards the lateral areas of the roll and whereby, when a roll in accordance with the invention is used, the percentage of shrinkage of the paper web (W) in the lateral areas is reduced and a favourable effect is applied to the uniformity of said shrinkage.
Claim 2
Dependent Claim
51 words
Suction roll as claimed in claim 1, characterized in that the partition-wall planes of the partition walls (17a,17b) placed in the suction space (13) in the interior of the roll mantle (11) of the suction roll (10) are placed substantially perpendicularly to the axis (X) of rotation of the roll (10).
Claim 3
Dependent Claim
87 words
Suction roll as claimed in claim 1 or 2, characterized in that in the interior of the roll (10), in the suction space (13), the vacuum spaces (A₁,A₂,A₃) are arranged symmetrically to the central axis of the roll, whereby, at the same distances from the centre line of the suction roll (10), similar vacuum spaces (A₁,A₃) are placed, into which substantially the same negative pressure is introduced, said negative pressure being higher than the negative pressure in any vacuum space between said vacuum spaces (A₁ and A₃).
Claim 4
Dependent Claim
46 words
Suction roll as claimed in any of the preceding claims, characterized in that the suction roll comprises an axle (18) of the suction roll, through whose interior ducts (18a,18b) the negative pressure is introduced into the inner vacuum and suction space (13) in the roll (10).
Claim 5
Dependent Claim
70 words
Suction roll as claimed in any of the preceding claims, characterized in that the axle (18) of the suction roll comprises two ducts (18a,18b), of which the first duct (18a) is fitted to be opened through an opening (19) placed on the surface of the axle (18) into the lateral vacuum space (A₁) between the partition wall (17a) and the end flange (27a) of the cylinder (FIG. 2B, FIG. 2C).
Claim 6
Dependent Claim
90 words
Suction roll as claimed in the preceding claim, characterized in that the duct (18a) is defined by the central transverse wall (21a) in the axle (18), by the tubular cover of the axle (18), and by the end wall (21b), whereby an air flow can be passed out of the vacuum space (A₁) placed between the partition wall (17a) and the end flange (27a) through the opening (19) provided on the axle (18) into the duct (18a) and further out of the suction space (arrow L₂) (FIG. 2B, FIG. 2C).
Claim 7
Dependent Claim
118 words
Suction roll as claimed in the preceding claim, characterized in that the suction roll includes a partition wall (17a), which is fixed permanently to the roll axle (18) and which partition-wall construction (17a) is connected with a bottom part (21c), which passes in the direction of the axis (X) of the roll towards the end flange (27a), whereby the space (A₁) is defined by the partition wall (17a) in the roll mantle (11) and by the end flange (27a) and by the bottom part (21c), a sector of negative pressure of a certain angle being formed by means of the construction to apply the suction to the paper web (W) within a desired zone (FIG. 2B, FIG. 2C).
Claim 8
Dependent Claim
113 words
Suction roll as claimed in any of the preceding claims 5, 6 or 7, characterized in that the suction roll includes a second partition wall (17b) at the other end of the roll and a vacuum space (A₂) in the middle area of the roll between the partition walls (17a and 17b), said vacuum space (A₂) being defined by the roll mantle (11), by the bottom wall (21d), and by the partition walls (17a,17b), whereby a suction flow can be passed through the perforations (23) in the roll mantle (11) into the second duct (18b) placed in the roll axle (18) through the opening (20) on the axle (18) (FIG. 2B, FIG. 2C).
Claim 9
Dependent Claim
74 words
Suction roll as claimed in any of the preceding claims, characterized in that the roll (10) comprises such vacuum spaces (A₁,A₂,A₃) in the interior of the roll in which, in the lateral vacuum spaces (A₁ and A₃), which correspond to each other in respect of their construction and dimensions, there are substantially equal negative pressures, which are higher than the negative pressure present in the space (A₂) in the middle area of the roll.
Claim 10
Dependent Claim
61 words
Suction roll as claimed in any of the preceding claims, characterized in that the partition walls (17a,17b) and the central axle (18) as well as the related wall constructions (21c,21d) are placed in stationary positions in relation to the roll mantle (11) rotated in relation to them as well as in relation to the end flanges (27a,27b) of the roll mantle.
Claim 11
Dependent Claim
70 words
Suction roll as claimed in any of the preceding claims, characterized in that the suction roll includes grooves (22) fitted in the mantle face of the roll mantle (11) and running in the direction of the circumference or as spiral shaped, perforations (23) being passed through the bottom parts of said grooves so as to direct a suction flow from outside the roll into the interior space in the roll.
Claim 12
Dependent Claim
61 words
Suction roll as claimed in claim 1, characterized in that the roll (10) comprises such vacuum spaces (A₁,A₂,A₃) in the interior of the roll in which the negative pressure is applied to the inner face (11') of the entire roll mantle (11) while the roll is not provided with a suction box or with an equivalent arrangement (FIG. 3A, FIG. 3B).
Claim 13
Dependent Claim
53 words
Suction roll as claimed in the preceding claim, characterized in that the suction roll comprises a number of holes (23) passing through the mantle (11) of the roll and from one end opening into the grooves (22) and from the other end into the interior of the cylinder (10) (FIG. 3A, FIG. 3B).
Claim 14
Dependent Claim
58 words
Suction roll as claimed in the preceding claim, characterized in that the ratio of the total cross-sectional flow area (A o ) of the holes (23) in the cylinder to the total cross-sectional flow area (A₁) of the perforated grooves (22) is in the range of 1:10...1:150, and preferably in the range of 1:50...1:110 (FIG. 3A, FIG. 3B).
Claim 15
Dependent Claim
135 words
Suction roll as claimed in the preceding claim, characterized in that the suction roll comprises such perforations (23) that the flow (Q) through the holes into the interior of the cylinder is in the range of 500...1500 m³/m/h, in which case the flow into the roll also through the area (S) free from web and felt remains within controlled limits, whereby the negative pressure in the vacuum spaces in the interior of the roll is maintained and whereby an adequate holding force (F) is achieved by means of the negative pressure to keep the paper web (W) in contact with the wire (H) or equivalent also in such roll positions in which the paper web runs outermost and, in particular, in the drying section at the beginning of the drying section (FIG. 3A, FIG. 3B).
Claim 16
Dependent Claim
79 words
Suction roll as claimed in any of the preceding claims, characterized in that the suction roll includes a separate pipe passage (24), which is passed through the hollow axle (18) of the roll, being passed through the partition wall (17b) to open itself into the space (A₂) in the middle area of the roll, whereby, through said pipe means, a suction flow (L₁) can be passed from the space (A₂) out of the roll construction (FIG. 3A, FIG. 3B).
Claim 17
Dependent Claim
125 words
Paper-machine suction roll as claimed in claim 1, characterized in that the suction roll comprises partition walls (17a and 17b), which are, at one end, defined by a bottom part (28), preferably a circular cylinder, in the interior of the roll, and that at least one partition wall (17a and/or 17b) comprises holes (29), whereby the negative pressure is produced into the space (A₂) defined by the partition walls (17a,17b), by the bottom part (28) and by the inner face (11') of the roll mantle through the holes (29), the air flowing out of the space (A₂) in the middle area of the roll into the adjoining space (A₁) in the lateral area and further out of connection with the roll (FIG. 4B, FIG. 4C).
Claim 18
Dependent Claim
53 words
Paper-machine suction roll as claimed in claim 17, characterized in that the negative pressure into the vacuum space (A₃) placed at the other end of the roll is introduced centrally through the roll through the tubular structure formed by the bottom part (28) of the circumferential zone (A₂) of negative pressure (FIG. 4C).
Claim 19
Dependent Claim
105 words
Paper-machine suction roll as claimed in claim 1, characterized in that the suction roll includes at least one partition wall (17a) that includes at least one hole or opening (29,31,34) passing through the partition wall, through which hole or opening the negative pressure is produced into the space placed at the opposite side of the partition wall (17) while the hole operates as a throttle member, whereby in the vacuum space placed at one side of the partition wall a lower negative pressure can be produced than in the space placed at the other side of the partition wall (FIG. 4C, FIG. 4D, FIG. 4E).
Claim 20
Dependent Claim
177 words
Method for the production of a desired pressure profile for a suction roll, which comprises a roll mantle (11), perforations (23) passed through said roll mantle, and a suction space (13) in the interior of the roll, which suction space can be subjected to negative pressure, characterized in that, in view of producing the desired profile of negative pressure across the width of the roll and in view of applying said profile of negative pressure to the paper web (W) to reduce the shrinkage of its lateral area and to equalize the shrink age of the paper web across the entire width of the web, negative pressure is applied to the paper web across the entire width of the paper web and so that, in the method, partition walls (17) are used, by means of which the suction space (13) in the interior of the roll is divided across the width of the roll into at least three vacuum spaces (A₁,A₂,A₃), whereby, in the method, the highest negative pressure is applied to the lateral vacuum spaces (A₁,A₃).
Claim 21
Dependent Claim
42 words
Method as claimed in the preceding claim, characterized in that in the method such partition walls (17a,17b) are used in the interior of the roll mantle (11) whose planes are placed substantially perpendicularly to the axis (X) of rotation of the roll.
Claim 22
Dependent Claim
50 words
Method as claimed in the preceding claim, characterized in that in the method substantially equally high negative pressures are produced into the vacuum spaces (A 1 , A 3 ;A 2 ,A n-1 ; A 3 ,A n-2 ...) placed at equal distances from the centre point of the roll.
Claim 23
Dependent Claim
72 words
Method as claimed in any of the preceding claims, characterized in that in the method a suction flow is produced through the perforations in the roll into the interior of the roll by pump means, and the suction is applied to the interior vacuum spaces in the roll through a separate system of ducts (18a,18b), which is passed through the roll axle (18) or which is formed into the roll axle (18).
References Cited (Backward Citations)
No citation records indexed.
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