JP3540368B2 - Press part of paper machine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a press part of a paper machine.
[0002]
[Prior art]
4 and 5 show examples of a conventional press arrangement including a double felt press, and FIG. 6 shows details of the double felt nip portion and a nip pressure profile thereof. FIGS. 4 and 5 are generally referred to as a traverse press and a trinip press, respectively, and are widely and generally applied as printing paper presses. In these press arrangements, the first press usually has a high dewatering load, and in order to obtain symmetry in paper quality, a double felt is used for dewatering with a nip pressure in a state where wet paper is sandwiched between two felts. A press mechanism is used. In this double nip press mechanism, a suction roll is used on the side where the wet paper web is transferred to the next-stage press, and a grooved roll having a groove for allowing felt water to escape is used as a mating roll forming a nip with the suction roll. Hereinafter, a conventional press arrangement will be described with reference to FIGS.
[0003]
In FIG. 4, the wet paper web (indicated by a dotted line) 2 on which the paper layer is formed in the previous step (wire part) is peeled off from the wire 1 by the suction pickup roll 3, accompanies the pickup felt 4, and 1 Press section 5-2 is entered.
No. In the first press section, as shown in FIG. The wet paper web 2 sandwiched between the press bottom felts 6 is pressed by the suction press rolls 7, 7 "and the No. 1 press bottom grooved roll 8 '. At this time, the normal suction roll hardness is JIS 95 ° (rubber roll). In the case of a roll), the hardness of the No. 1 grooved roll 8 'is as high as JIS99 °, so that the rubber layer on the grooved roll side has little deformation and the nip width is not very wide.
Accordingly, with the nip pressure profile as shown in FIG. It is dewatered on both sides through one press bottom felt 6. Thereafter, the wet paper web 2 is sucked and held by the pick-up felt 4 side by the vacuum force applied to the suction press rolls 7, 7 ", and is transported around the suction rolls. The paper web 16 is further dewatered, peeled off from the center roll 15, and sent to the next process via the paper roll 16. In order to ensure the transfer of the wet paper web 2 to the pick-up felt 4 side after the No. 1 press, The felt roll 9 'is arranged so that the No. 1 press bottom felt 6 is slightly held (usually θ = 5 to 8 °) on the suction roll 7 side after the nip.
[0004]
No. No. 1 press section 5-2 and No. 1 In general, a steam box 10 is arranged between the two press sections 11 so as to oppose the suction roll 7 for the purpose of humidifying the wet paper 2 and correcting the moisture profile. Further, a doctor 17 for removing the wet paper web is provided below the center roll 15.
Next, the case of the trinip press arrangement of FIG. The configuration and operation up to passing through one press section 5-3 are the same as those of the traffic press of FIG. However, in the Trinip press, No. Since the press nip 11 'is formed by the suction roll 7 "and the center roll 15', the space formed by the No. 1 bottom felt 6, the suction roll 7" and the center roll 15 'is smaller than that of the traverse press. There is not much space for the arrangement of the steam box 10 and the doctor 17. Therefore, the suction roll 7 "and the center roll 15 'are made larger than in the case of the traverse press, and the position of the felt roll 9" on the exit side of the No. 1 press section 5-3 is lowered to secure a space. Is the current situation.
[0005]
[Problems to be solved by the invention]
Conventional No. No. 1 in the press sections 5-2 and 5-3. Since the rubber hardness of one grooved roll 8 ″ was high, the nip width was narrow, and the pressure density of the outer layer of the wet paper was increased due to rapid dewatering action, resulting in poor dewatering efficiency in the subsequent press.
Recently, in the standard traverse press, the vacuum chamber has been changed from two chambers of Hi (-500 mmHg) and Low (-250 mmHg) to one chamber of Mid (-380 mmHg). Since the degree of vacuum is low, in order to reliably transfer wet paper, It is necessary to hold one bottom felt 6 on a suction roll. However, during operation, there was a problem that the bottom felt moisture returned to the wet paper due to the vacuum force and re-wet (rewet).
Further, in the trinip press, there is a problem that the diameter of the suction roll or the center roll needs to be increased in order to obtain a space for disposing the steam box 10 and the doctor 17 of the center roll, thereby increasing the cost.
The present invention intends to provide a press part of a paper machine capable of obtaining a dewatered form with a slow and long dewatering time, increasing press dewatering efficiency, preventing rewetting during operation, and reducing costs. is there.
[0006]
[Means for Solving the Problems]
For this reason, the present invention relates to a press part of a paper machine having a first press and a second press disposed downstream of the first press, wherein the first press comprises a pair of suction rolls and grooved rolls . the press nip formed from the wet paper through the two felt a press with double felt suction press roll to perform dehydration, the grooved roll is a rubber covered roll, a rubber hardness of the suction roll that In a press part of a paper machine having a first press and a second press arranged downstream of the first press , the first press is formed by a rubber layer sufficiently lower than the hardness. Double felt for dewatering from wet paper web through two felts by a press nip formed by a pair of suction rolls and grooved rolls A press having a traction press roll, wherein the grooved roll is a rubber-coated roll, the rubber hardness of which is formed of a rubber layer having a JIS of 88 ° or less, and further comprising the rubber of the grooved roll. are those capable of reducing the dehydration resistance in the second press the layer positioned on the downstream side of the first press to prevent compaction of the wet paper, there further delivery side of the press nip, the grooved roll those felt roll guiding the felt side is its position variably supported, formed by further traveling to the felt of the grooved roll side is wound on the grooved roll in the press nip exit side These are used as means for solving the problems.
[0007]
[Action]
In the present invention, By making the rubber hardness of one grooved roll (grooved roll) sufficiently lower than that of the mating suction roll, the nip width is increased (l> l ') and the peak value of the nip pressure is reduced (P <P'), A gentle dehydration form can be obtained. Such dehydration over time at a low unit pressure increases dehydration in a place with a large amount of moisture, prevents the paper layer from being densified by a steep pressure gradient, and increases dehydration efficiency in a subsequent press.
[0008]
In the case of a vacuum press having one vacuum chamber, No. The felt roll position on the exit side of the press nip is made variable. By setting the bottom felt to the suction roll so that it is held by the suction roll, the wet paper can be reliably transferred to the pickup felt side even when the degree of vacuum is low, and set to the lowered position during operation. As a result, no. No. 1 bottom felt is separated from the wet paper web. There is no danger of rewetting due to the return of the moisture of one bottom felt to the wet paper.
[0009]
Furthermore, in a traverse press having two Hi-Low vacuum chambers or a tri-nip press of Hi-Low-Hi, the bottom felt can be obtained at the nip exit side because a vacuum degree necessary for transferring wet paper is obtained at the time of paper passing. Even without being held by the suction roll, the wet paper web moves to the pickup felt side. Therefore, the felt roll can be omitted, and the re-wetting during operation can be prevented as described above. In the trinip press, the space for installing the doctor and the steam box can be widened, and the cost can be reduced without any problem even if the suction roll and center roll diameters are the same as those of the tiger event.
[0010]
【Example】
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the embodiments of the drawings. FIGS. 1 to 3 show embodiments of the present invention, and FIGS. 1 and 2 are front views of a traverse type and a trinip type press part employing a press mechanism arrangement. , FIG. FIG. 3 shows a detailed view of one press nip portion. 1 and 2, the wet paper web 2 in which the paper layer is formed in the wire part in the previous process is peeled off from the wire 1 by the pickup roll 3, and the wet paper web 2 is formed with the pickup felt 4 together with the pickup felt 4. 1. Enter the press nip portion 5 or 5-1 (FIG. 3).
Here, the wet paper 2 is made up of the pickup felt 4 and the No. 1 with suction press roll 7 or 7 ′ sandwiched between bottom felts 6. Dewatering is performed by a press nip formed by one grooved roll (grooved roll) 8. At this time, No. Since the surface of the one grooved roll 8 is formed of a rubber layer having a low hardness (JIS 88 ° or less is preferable), the surface is easily deformed, the nip width (l) is widened, and a gentle dehydration having a low peak pressure P even at the same pressure. And the dehydration time t also becomes longer.
[0011]
No. In one press nip, since the moisture in the wet paper web 2 is large, so high pressure is not required for dehydration, and the dehydration time becomes longer, so that dehydration is increased. On the other hand, since the dewatering pressure gradient is small, it is possible to prevent the outer layer from being consolidated, and the dewatering resistance at the time of the subsequent pressing is reduced, and the dewatering efficiency is increased. It has been found that the problem of peeling of the rubber layer (Japanese Patent Application No. 5-44366) can be sufficiently put to practical use by increasing the roll diameter due to the heat generated by lowering the rubber hardness. The blockage of the groove for draining the dewatered water through the felt can be dealt with by widening in consideration of deformation.
[0012]
Next, No. The operation of the embodiment of the present invention at the exit of one press nip will be described. In a double felt type press, suction rolls are used to transfer wet paper to the next press. For the purpose of simplification and high dehydration, the conventional dehydration zone has a high vacuum (Hi), and the wet paper web holding zone has a low vacuum (Lo), a Hi-Lo two-chamber type (travent press), a Hi-Lo-Hi three chamber. The type in which the first half of the Hi-Lo chamber from the type (trinip press) is a medium vacuum (Mid) chamber is standard. In the case of such a suction roll type, it is necessary to achieve a reliable transfer of the wet paper to the suction roll side at the time of paper passing.
[0013]
In the present invention, as shown in FIG. No. 1 is set by supporting the felt roll 9 on the exit side of the press nip so that its position is variable, and setting the felt roll 9 to the ascending position (indicated by a dashed line) during paper passing. No. 1 bottom felt 6 can be held by the suction roll 7, and the wet paper web 2 is surely no. The operation is shifted to the press nip 11 and the felt roll 9 is set to the lowered position during operation, and the bottom felt 6 is separated from the wet paper 2 immediately after the nip so that rewetting can be prevented. I have.
Further, in the case of a conventional nip having a suction roll type, as shown in FIG. By removing the felt roll on the one press nip 5-1 exit side, the bottom felt 6 runs along the bottom roll 8, so that the space on the nip exit side is widened. Therefore, even if the suction roll 7 'and the center roll 15 have the same diameter as in the case of the traverse press, the cost can be reduced without any problem in installing the steam box 10 and the doctor 17.
[0014]
【The invention's effect】
As described above in detail, according to the present invention, by reducing the rubber roll hardness of the grooved roll in the double felt press, a dewatering mode that is slow and has a long dewatering time can be obtained, and the press dewatering efficiency can be increased.
Further, by supporting the felt roll on the exit side of the double felt nip so that its position is variable, it is possible to prevent rewetting during operation. Further, by eliminating the felt roll, the diameter of the suction roll and the center roll in the trinip press can be reduced, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a front view of a press arrangement in a press part of a paper machine according to a first embodiment of the present invention.
FIG. 2 is a front view of a press arrangement in a paper machine press part according to a second embodiment of the present invention.
FIG. 3 is a diagram showing a No. 1 according to the first and second embodiments of FIGS. It is a detailed sectional view of one press nip part.
FIG. 4 is a front view showing an example of a conventional tiger event press.
FIG. 5 is a front view showing an example of a conventional trinip press.
FIG. 6 is a detailed sectional view showing a conventional press nip portion in FIGS. 4 and 5;
[Explanation of symbols]
1 wire 2 wet paper 3 pickup roll 4 pickup felt 5, 5-1 No. 1 No. 1 press nip 6 No. No. 1 bottom felt 7, 7 'suction press roll 8 No. 1 1 grooved roll (grooved roll)
9 Felt roll 10 Steam box 11 No. 2 press nip 15 center roll 17 doctor

Claims (5)

In the press part of a paper machine having a second press which is disposed downstream of the first press and the first press, the first press by a press nip formed by a pair of suction roll and grooved roll a press with a double felt suction press roll to perform dehydration from the wet paper through the two felts, the a grooved roll rubber covered rolls, sufficiently lower rubber layer than the hardness of the rubber hardness the suction roll A press part for a paper machine, characterized by being formed of: In a press part of a paper machine having a first press and a second press arranged downstream of the first press, the first press is formed by a press nip formed by a pair of suction rolls and grooved rolls. A press having a double felt suction press roll for dewatering wet paper via two felts, wherein the grooved roll is a rubber-coated roll, the rubber hardness of which is formed by a rubber layer having a JIS of 88 ° or less. A press part for a paper machine. The papermaking machine according to claim 1, wherein the rubber layer of the grooved roll prevents the wet paper from consolidating, and can reduce dewatering resistance in the second press located downstream of the first press. 4. Press part of the machine. In the delivery side of the press nip, the press part of claim 1 or 2, wherein the paper machine felt roll for guiding the felt of the grooved roll side, characterized in that it is supported the position variable . Paper machine press part according to claim 1, wherein the felt of the grooved roll side, characterized in that the running to be wound around the grooved roll in the press nip exit side.

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