JP2002212892A - Calender and method for calender treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing of a backup roll with a proper load even in the case of low linear load of a calendering nip. SOLUTION: In a calendering in which a long material passing through a nip N1 formed between a hot roll 12 and a backup roll 14 is calendered, the hot roll 12 has a recessed negative crown 23. Consequently, since a gap 27 is produced in the nip N1, in order to provide a fixed nip linear load, a press shoe 24 presses the shell 25 of the backup roll 14 toward the nip N1 more excessively than a common case. The bearings 32 and 34 are provided the reaction as a load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a calendar and a calendar processing method.

[0002]

2. Description of the Related Art Calendar processing of a long material such as paper web, rubber, asbestos, and metal foil is performed by a long nip formed between a hot roll for heating the long material and a backup roll contacting the hot roll. It is done through the shank. However, each roll is slightly curved because it is not completely rigid, creating a gap in the nip. Therefore, the linear pressure generated in the nip tends to increase at both ends of the roll and decrease at the center. Such non-uniformity of the linear pressure causes incomplete calendering and adversely affects the long material.

In order to solve such a problem, a crown roll has conventionally been used. The crown roll has an outwardly convex shape (crown) at the center of the roll, and eliminates non-uniform linear pressure. There is also a crown adjusting roll capable of adjusting the amount of crown according to the type of long material, and is described in, for example, Japanese Patent Publication No. 58-46599 and Japanese Patent Application Laid-Open No. 6-65888.

The crown adjusting roll includes, for example, a hydraulic cylinder inside the roll. The hydraulic cylinder extends radially based on the rotation axis of the roll. The tip of the cylinder is a pressing shoe that presses the inside of the outer shell of the roll. The holding shoe presses the roll shell from inside toward the nip, causing the shell to protrude outward. By using this, a desired linear pressure can be applied to the nip according to the gap of the calender nip or the type of the long material.

[0005]

However, when the linear pressure required for the nip is low, the load applied to the bearing of the crown adjusting roll becomes small as a reaction of the pressing shoe pressing the roll shell. On the other hand, the load that the bearing receives from the roll must always maintain a predetermined magnitude, and should not be less than several percent of the dynamic load rating specific to the bearing. If rotation continues under a substantially no-load condition of several percent or less of the dynamic load rating, the rolling rollers that constitute the rolling bearing of the bearing may not roll properly, or streaks may appear on the bearing case. This is because a problem such as peeling occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a calendar and a calendar processing method in which the disadvantages of the prior art are eliminated and the bearing does not fail.

[0007]

According to the present invention, there is provided a calender for calendering a long material passing through a nip formed between a backup roll and a hot roll. It has a concave crown.

According to the present invention, there is provided a calendering method for applying a predetermined nip linear pressure to a nip formed between a backup roll and a hot roll to calender a long material passing through the nip. Has a concave crown, and a calendaring method includes a step of pushing a shell of a backup roll from the inside of the roll toward the nip to apply a predetermined nip linear pressure to a nip where a gap is formed by the concave crown. And applying a load to the bearing of the backup roll by a reaction of the pushing step.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a calendar and a calendar processing method according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, elements not directly related to the present invention are omitted. The same elements are denoted by the same reference numerals. In the following embodiments, the paper web W is used as a representative of the long material, but the present invention can be applied to other long materials.

FIG. 2 is a diagram showing a calendar 10 according to the present invention. The paper web W passes through continuous calendering nips N1 and N2 in order to calender the upper and lower surfaces.
The first nip N1 is formed between a hot roll (hard surface roll) 12 disposed above and a backup roll (soft surface roll) 14 disposed below. The hot roll 12 calenders the upper surface of the paper web W by heating. The backup roll 14 has a shell made of a soft material such as rubber, and presses the paper web W against the hot roll 12. In this way, a predetermined linear pressure is provided to the nip N1 so that the upper surface of the paper web W is subjected to a sufficient calendering process. On the other hand, the hot roll 16 and the backup roll 18 that form the nip N2 are arranged in reverse to those described above. This allows the nip
At N2, a calendar process is performed on the lower surface of the paper web W.

As described above, the backup rolls 14 and 18 apply pressure to the hot rolls 12 and 16 to obtain a predetermined linear pressure. Therefore, as a reaction, the load 2 shown by the arrow in FIG.
It takes 0 and 22. Next, how these loads 20, 22 are generated will be described with reference to FIG.

FIG. 1 is a front view of each of the rolls 12, 14 forming the first nip N1 of FIG. The internal state of the backup roll 14 is shown. A feature of the present invention is that, as shown in FIG. 1, the shell of the hot roll 12 has a concave surface 23 which is depressed inward. Hereinafter, this is referred to as a negative crown. Usually, the crown means that the central portion of the roll has an outwardly convex shape, but this is because the crown is formed in the inward direction. Due to the negative crown 23, a gap 27 is intentionally generated in the nip N1. In FIG. 2, as one form of the negative crown,
Although a drum-shaped hot roll 12 is shown, any negative crown may be used as long as the effects of the present invention can be exerted.

On the other hand, the backup roll 14 includes a plurality of holding shoes 24 therein. These are arranged in the width direction, and for convenience of illustration, only a limited number is shown,
The number may be more than the illustrated number or the following number. The holding shoe 24 is in contact with the inner surface of the shell 25 of the backup roll 14. The holding shoe 24 is supported by a piston 26. The piston 26 presses the holding shoe 24 against the shell 25 by a hydraulic mechanism described later. The shell 25 of the backup roll 14 indicated by oblique lines is rotated by a driving device such as a motor (not shown). On the other hand, the fixed shaft 28
The pressing shoe 24 fixed thereto does not move even when the shell 25 rotates, and comes into contact with the shell 25 as a sliding bearing.

FIG. 3 is a sectional view of the backup roll 14 of FIG. The holding shoe 24 is driven by a hydraulic cylinder mechanism provided on the fixed shaft 28. That is, shoe 24
Is pressed against the shell 25 by a hydraulic mechanism using the fixed shaft 28 as a base. Then, the reaction is transmitted to the bearings 32 and 34 via the fixed shaft 28.

As shown in FIG. 3, in this embodiment, the holding shoes 24 are arranged in each direction which divides the circumference of the shell 25 into three equal parts. By adjusting the amount of oil 29 of the hydraulic mechanism, the piston 26 is pressed by the hydraulic pressure, and the pressing shoe 24 is pressed against the shell 25. Note that the arrangement of the holding shoe 24 and the hydraulic mechanism for driving the holding shoe 24 may be arranged in any number of directions other than the three directions, and the circumference need not necessarily be equally divided. The hydraulic mechanism should be at least nip
What is necessary is just to equip the holding shoe row arranged with respect to N1, and the other two-way shoe row does not need to have a hydraulic mechanism.

The inner surface of the shell 25 of the backup roll 14 is pressed by the pressing shoe 24, and the linear pressure of the nip N1 is adjusted. Although not shown, the nip linear pressure is controlled by a nip linear pressure control mechanism. According to this control mechanism,
The nip linear pressure is measured by the measuring means, and the feedback is fed back to operate the hydraulic mechanism of the holding shoe 24 so that a predetermined nip linear pressure is obtained.

The operation of the calendar 10 according to the present invention configured as described above will be described. In the calendar processing, in order to obtain a predetermined nip linear pressure, the hydraulic pressure level of the backup roll 14 with respect to the negative crown 23 may be increased. That is, the inner surface of the shell 25 of the backup roll 14 may be pressed against the nip N1 by the holding shoe 24. However, in the case of this example, when compared with the case of a hot roll having no crown applied,
Since the hard surface hot roll 12 has a negative crown 23, the holding shoe 24
Must press the inner surface of the shell 25 extra. Therefore, as compared with the case of a normal hot roll without a negative crown, the holding shoe 24 of the present invention is used.
The (hydraulic piston) needs to be more protruded.

The pressing shoe 24 strongly presses the inner surface of the shell 25 by the amount of extra projection. Thus, the reaction is greater than without the negative crown, and the reaction via the fixed shaft 28 places more pressure on the bearings 32, 34 than usual. Therefore,
Even if the nip linear pressure required in the nip N1 is a low linear pressure, the nip N1 can escape from the range of several percent or less of the dynamic load rating of the bearings 32 and 34. The present invention thus provides for the intentional gap 27 in the nip N1 by the negative crown 23.
And a large load is applied to the bearings 32 and 34 using the linear pressure control mechanism of the backup roll 14 as a crown adjusting roll.

The backup roll 14, that is, a soft surface roll made of a material such as rubber, may be provided with a negative crown, but in this case, polishing is required at a relatively short cycle. Therefore, in this embodiment, a negative crown is provided on the side of the metal hot roll having a long polishing cycle. The metal mentioned here is, for example, chilled cast iron.

FIG. 4 shows the linear pressure at the first nip N1 of FIG. 2 and the load 20 on the bearings 32 and 34 of the backup roll 14.
FIG. 5 is a graph showing the relationship between the linear pressure at the second nip N2 and the bearing load 22 of the backup roll 18.
6 is a graph showing a relationship with the graph. Hot rolls 12, 16 are width
3515 mm, diameter 812 mm, backup rolls 14, 18
Is 3485 mm wide and 655 mm in diameter. The size of the negative crown of the hot rolls 12, 16 is such that a difference of 0.25 mm in diameter occurs between the end and the center of the hot roll. 4 and 5, the load applied in the direction opposite to the hot rolls 12 and 16, ie, the load in the direction indicated by the arrow in FIG.
20, 22 are represented as negative loads. In FIGS. 4 and 5, the failure of the bearings of the backup rolls 14 and 18 occurs in a range of 1% or less of the dynamic load rating of 2730 kN (kilonewton).

In FIG. 4, which is a graph of the first nip N1, a straight line 40 in the case where there is no negative crown 23 is shown.
See Then, in the first nip N1, in the state A where almost no linear pressure is applied, the weight of the backup roll 14 itself is applied to the bearings 32 and 34 as a negative load. Then, as the linear pressure required in the nip N1 increases, the load on the bearings 32, 34 also increases. When the linear pressure is low, it is not included in the range B of 1% or less of the dynamic load rating, but is in a dangerous area. On the other hand, according to the straight line 42 provided with the negative crown, the linear pressure is low C
Even in this case, the load is additionally applied to the bearings 32 and 34, so that the bearing does not fail.

In FIG. 5, which is a graph of the second nip N2, reference is made to a straight line 44 in the case where there is no negative crown. Then, in the second nip N2, in the state D where almost no linear pressure is applied, the weight of the backup roll 18 itself is applied to the bearing as a positive load. In this case, since the backup roll 18 is supported by the hot roll 16, its weight is slightly reduced. Therefore, even if the same backup roll is used as the first nip N1, the absolute value of the weight is slightly smaller.
Therefore, there is a possibility that the bearing falls within the range B of 1% or less of the dynamic load rating, thereby causing a bearing failure. Then, as the linear pressure required in the nip N2 increases, the load on the bearing also increases. However, if the nip linear pressure does not increase significantly, it is impossible to escape to a safe area. On the other hand, according to the straight line 46 provided with the negative crown, even in the state E where the linear pressure is low, an additional load is applied to the bearing.
% Or less, and bearing failure does not occur.

[0023]

As described above, according to the present invention, a high load can be applied to the bearing of the backup roll even when the linear pressure of the nip of the calendar is low. as a result,
Does not cause bearing failure.

[Brief description of the drawings]

FIG. 1 is a front view of each roll forming a nip of a calendar according to the present invention.

FIG. 2 shows a calendar according to the invention.

FIG. 3 is a cross-sectional view of the backup roll of FIG. 1 viewed from a width direction.

FIG. 4 is a graph showing a relationship between a linear pressure at a first nip in FIG. 2 and a load on a bearing of a backup roll.

FIG. 5 is a graph showing a relationship between a linear pressure at a second nip in FIG. 2 and a load on a bearing of a backup roll.

[Explanation of symbols]

 10 Calendar 12, 16 Hot roll 14, 18 Backup roll 23 Negative crown 24 Holding shoe 25 Shell 32, 34 Bearing N1, N2 Nip

Claims (3)

[Claims] 1. A calender for calendering a long material passing through a nip formed between a backup roll and a hot roll, wherein the hot roll has a concave crown. 2. The calendar according to claim 1, wherein the backup roll includes a shell of the backup roll for applying a predetermined nip linear pressure to the nip having a gap formed by the concave crown of the hot roll. A calender comprising: pressing means for pressing the inside of the roll toward the nip; and a bearing which is loaded by a reaction of a force for pressing the shell toward the nip. 3. A calendar processing method for applying a predetermined nip linear pressure to a nip formed between a backup roll and a hot roll to perform a calendar process on a long material passing through the nip. Having a crown of shape, the method comprising: pushing a shell of the backup roll from inside the roll toward the nip to apply a predetermined nip linear pressure to the nip gapped by the concave crown. And a step of applying a load to a bearing of the backup roll by a reaction of the pressing step.