JPH0813372A - Press part for papermachine - Google Patents

Abstract

PURPOSE:To increase press dehydrating efficiency, to prevent rewetting in operation, to reduce the radius of a center roll and to drop a cost. CONSTITUTION:In a press part of a paper machine of double felt suction press roll arrangement in which a pair of suction rolls and a grooved roll (press bottom roll 8) form a press nip and wet paper 2 is dehydrated through two sheets of felts 4 and 6, the grooved roll 8 is made of a rubber layer having hardness sufficiently lower than that of a rubber-coated roll 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press part of a paper machine.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show an example of a conventional press arrangement including a double felt press, and FIG. 6 shows details of the double felt nip portion and its nip pressure profile. 4 and 5 are commonly called a tray event press and a tri-nip press, respectively, and are widely and generally applied as a printing paper press. In these press arrangements, the first press usually has a high dewatering load, and in order to obtain the symmetry of the paper quality, the double felt that dewaters by the nip pressure with the wet paper 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 letting water out of the felt is used as a partner roll forming a nip with the suction roll. The conventional press arrangement will be described below with reference to FIGS. 4, 5 and 6.

In FIG. 4, a wet paper web (indicated by a dotted line) 2 having a paper layer formed in the previous step (wire part) is peeled off from the wire 1 by a suction pickup roll 3 and runs along with a pickup felt 4 to form a No. 1 press section 5
-2. No. In the 1st press section, as shown in FIG. The wet paper web 2 sandwiched between the 1st press bottom felt 6 is a suction press roll 7, 7 ″ and a No. 1 press bottom grooved roll 8 ′.
Is pressurized by. At this time, the normal suction roll hardness is JIS 95 ° (for rubber winding roll), No. Since the hardness of 1 grooved roll 8'is as high as JIS 99 °, the rubber layer on the grooved roll side is not deformed so much and the nip width is not so wide. Therefore, with the nip pressure profile as shown in FIG. 6, a high dehydration pressure P ′ acts for a short time t ′, and the pickup felt 4 and No. 1 press bottom felt 6
Both sides are dehydrated through. Then, the wet paper web 2 is sucked and held by the pickup felt 4 side by the vacuum force applied to the suction press rolls 7 and 7 ″ and transported around the suction rolls.
3 Press section 13 and further dehydrated, center roll 15
It is peeled off and sent to the next step through the paper roll 16. In addition, No. In order to ensure the transfer of the wet paper web 2 to the pickup felt 4 side after 1 press, No. The felt roll 9'is arranged so that the 1-press bottom felt 6 is held to the suction roll 7 side for a short time (usually θ = 5 to 8 °) after the nip.

No. 1 press section 5-2 and No. 1 press section 5-2. A steam box 10 is usually arranged between the two press sections 11 so as to face the suction roll 7 for the purpose of humidifying the wet paper web 2 and correcting the moisture profile. Further, a wet paper stripping doctor 17 is provided below the center roll 15. Next, the case of the tri-nip press arrangement shown in FIG. The structure and operation up to passing through the first press section 5-3 are the same as those of the tray event press of FIG. However, in the tri-nip press, N
o. Since the 2 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 narrower than that of the tray event press. There is not enough space for the steam box 10 and the doctor 17. Therefore, the suction roll 7 "and the center roll 15 'can be made larger than in the case of the tiger event press,
No. In the present situation, the space is secured by lowering the position of the felt roll 9 ″ on the exit side of the 1st press section 5-3.

[0005]

[Problems to be Solved by the Invention] No. 1 in the press parts 5-2 and 5-3. Since 1 grooved roll 8 ″ has a high rubber hardness, the nip width is narrow, and the pressure density of the outer layer of the wet paper is high due to the rapid dewatering action, and the dewatering efficiency in the subsequent press is poor. Vacuum chamber is Hi (-500mmHg), Low
From (-250mmHg) 2 chambers, Mid (-380mmHg)
No. 1 in order to obtain a reliable transfer of the wet paper because the degree of vacuum is low when passing the paper without the wet paper. 1 Bottom felt 6 needs to be held in the suction roll.
However, during operation, the bottom felt moisture returned to the wet paper due to the vacuum force and was re-wet. Further, in the tri-nip press, in order to obtain a space for disposing the steam box 10 and the doctor 17 for the center roll, it is necessary to increase the diameter of the suction roll and the center roll, which causes a problem of high cost. INDUSTRIAL APPLICABILITY The present invention provides a slow dehydration form having a long dehydration time, increases press dehydration efficiency, and prevents rewetting during operation,
In addition, it is intended to provide a press part of a paper machine that can reduce costs.

[0006]

For this reason, the present invention is directed to a double felt suction press roll arrangement in which a pair of suction rolls and grooved rolls form a press nip and dehydration is performed from a wet paper web through two felts. In the press part of the paper machine, the grooved roll is a rubber-coated roll, the rubber hardness of which is formed of a rubber layer sufficiently lower than the mating suction roll hardness, and at the exit side of the press roll nip. The felt roll that guides the felt on the grooved roll side supports its position variably, and there is no felt roll, and the felt on the grooved roll side can be wound around the grooved roll at the nip exit side. It is made by running, and these are used as means for solving the problems.

[0007]

In the present invention, in No. By making the rubber hardness of the 1-grooved roll (grooved roll) sufficiently lower than that of the mating suction roll, the nip width becomes wider (l> l ').
At the same time, the peak value of nip pressure becomes lower (P <P '),
A mild dehydration form can be obtained. Dehydration over time at such a low unit pressure increases dewatering in a place where the water content is high, and prevents consolidation of the paper layer due to a rapid pressure gradient, thereby increasing the dewatering efficiency in the subsequent press.

In a tray event press having a single vacuum chamber, No. 1 The felt roll position on the exit side of the press nip is made variable, and No. 1 By setting the bottom felt to the suction roll so that it is held in the suction roll, the wet paper can be reliably transferred to the pickup felt side even when the vacuum level is low, and it is set to the lower position during operation. As a result, N immediately after the nip
o. No. 1 bottom felt is separated from the wet paper, so no. 1 There is no risk of rewetting due to the water in the bottom felt returning to the wet paper.

Furthermore, in a tray event press having two Hi-Low vacuum chambers or a Hi-Low-Hi tri-nip press, the degree of vacuum required for transfer of wet paper during paper passage is obtained, so that at the nip exit side. Even if the bottom felt is not held on the suction roll, the wet paper moves to the pickup felt side. Therefore, the felt roll can be eliminated, and rewetting during operation can be prevented as in the above case. In the tri-nip press, a space for installing a doctor and a steam box can be widened, and even if the suction roll and the center roll have the same diameter as that of the tiger event, the cost can be reduced without any problem.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIG. 1 to FIG.
Is a front view of a tray event type and a tri-nip type press part adopting a press mechanism arrangement, and FIG. 1 shows a detailed view of a press nip portion. In FIGS. 1 and 2, the wet paper 2 having a paper layer formed by the wire part, which is the previous step, is stripped from the wire 1 by the pickup roll 3,
No. with pickup felt 4 1 Enter the press nip portion 5 or 5-1 (FIG. 3). Here, the wet paper 2 is
Pickup felt 4 and No. No. 1 bottom felt 6 and the suction press roll 7 or 7 ′ and No. 1 bottom felt 6. It is dehydrated by a press nip formed by 1 grooved roll (grooved roll) 8. At this time, No. The surface of the 1-grooved roll 8 has low hardness (JIS 88 °
(The following is preferable) Since it is formed of a rubber layer, it is easily deformed, the nip width (l) is widened, and even with the same pressing force, the peak pressure P is low, the dehydration is gentle, and the dehydration time t is long.

No. Since the wet paper 2 contains a large amount of water in one press nip, a high pressure is not required for dehydration, and the dehydration time becomes long, so that dehydration can be increased. On the other hand, since the dehydration pressure gradient is also small, it is possible to prevent the outer layer from being consolidated, and the dehydration resistance at the time of pressing in the subsequent stage is reduced, so that the dehydration efficiency is increased. It was found that the problem of peeling of the rubber layer (Japanese Patent Application No. 5-44366) due to the heat generated by lowering the rubber hardness can be sufficiently put to practical use by increasing the roll diameter. Further, the blockage of the groove for discharging the dehydrated water through the felt can be dealt with by widening it in consideration of deformation.

Next, No. 1 The operation of the embodiment of the present invention on the exit side of the press nip will be described. In the double-felt type press, a suction roll is used to transfer the wet paper web to the next-stage press. For the purpose of simplification and high dehydration, Hi-Lo 2 chamber type (Tra-event press), Hi-Lo-Hi 3 chamber, where the conventional dehydration zone is high vacuum (Hi) and the wet paper web holding zone is low vacuum (Lo) From the type (Tri-nip press) to the first half of the Hi-Lo2 chamber, the medium vacuum (Mi
d) The standard type is one room. In the case of such a suction roll type, it is necessary to achieve a reliable transfer of the wet paper web to the suction roll side during paper passing.

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 can be changed, and setting the felt roll 9 to the raised position (shown by the alternate long and short dash line) when passing the paper. The bottom felt 6 can be held by the suction roll 7, and the wet paper 2 can be surely placed on the side of the nip. 2 The press nip 11 is moved to, the felt roll 9 is set to the lowered position during operation, and the bottom felt 6 is immediately after the nip.
Considering that it can be prevented from re-wetting by moving it away from. Further, in the case of the trinip having the conventional suction roll type, as shown in FIG. By removing the felt roll on the exit side of the 1st press nip 5-1, the bottom felt 6 runs along the bottom roll 8, so that the space on the exit side of the nip becomes wider. Therefore, even if the suction roll 7'and the center roll 15 have the same diameter as in the case of the tray event press, there is no problem in installing the steam box 10 and the doctor 17,
Cost can be reduced.

[0014]

As described in detail above, according to the present invention, by lowering the rubber winding hardness of the grooved roll in the double felt press, a dewatering mode with a gentle and long dewatering time can be obtained, and the press dewatering efficiency can be increased. Can be planned. Further, by supporting the felt roll on the exit side of the double felt nip so that its position is variable, rewetting during operation can be prevented. Further, by removing the felt roll, the diameter of the suction roll and the center roll in the tri-nip press can be reduced, and the cost can be reduced.

[Brief description of 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 an N according to the first and second embodiments of FIGS. 1 and 2;
o. It is a detailed sectional view of one press nip portion.

FIG. 4 is a front view showing an example of a conventional tray event press.

FIG. 5 is a front view showing an example of a conventional tri-nip press.

FIG. 6 is a detailed sectional view showing a press nip portion in FIGS. 4 and 5 of the related art.

[Explanation of symbols]

 1 wire 2 wet paper 3 pickup roll 4 pickup felt 5,5-1 No. 1 Press nip 6 No. 1 Bottom felt 7,7 'Suction press roll 8 No. 1 grooved roll (grooved roll) 9 felt roll 10 steam box 11 No. 2 Press nip 15 Center roll 17 Doctor

Claims (3)

[Claims] 1. A pair of suction rolls and a grooved roll form a press nip, and in a press part of a paper machine having a double felt suction press roll arrangement for dehydrating a wet paper web through two felts, a grooved groove is formed. A press part of a paper machine, wherein the roll is a rubber-coated roll, and the rubber layer is formed of a rubber layer having a rubber hardness sufficiently lower than the hardness of a counterpart suction roll. 2. The paper machine according to claim 1, wherein a felt roll for guiding the felt on the grooved roll side is variably supported on the exit side of the press roll nip. Press part. 3. The press part of a paper machine according to claim 1, wherein the felt roll is provided without the felt roll and the felt on the grooved roll side is wound around the grooved roll at the nip exit side. .