JP2007506051A - Braking arrangement for damping mechanical vibrations in rolls in paper or paperboard forming machines - Google Patents

Abstract

  The present invention relates to a braking structure for damping mechanical peripheral vibrations and beam-like vibrations in a roll in a paper or paperboard forming machine. The roll (1) comprises an essentially rigid shell (2). The braking structure additionally includes an inner shell (3) and a braking structure (4) arranged between the shell (1) and the inner shell (3). During the period of roll (1) vibration, the force caused by the difference in motion between the shell (2) and the inner shell (3) is converted into a shear force in the production structure, which is applied to the braking structure (4). Disappears in nature.

Description

  The present invention relates to a braking structure for mechanical peripheral and beam-like vibrations in a roll in a paper or paperboard forming machine, the roll comprising an essentially rigid shell.

  Today, mechanical vibrations of rolls that occur at frequencies below 200 Hz are becoming increasingly problematic in paper or board forming machines. This is mainly due to the continuous speed increase of the paper forming machine. Specifically, problems caused by vibration in the tangential direction of the outer periphery of the roll, that is, so-called peripheral vibration, increase as the speed of the machine increases. Peripheral vibration is therefore a serious problem with the operability of paper or paperboard machines, as well as mechanical vibrations of other types of rolls, ie the longitudinal beam vibrations of the roll.

  Vibration significantly impedes the production of paper and paperboard, thus limiting the increase in machine speed. The vibration problem increases exponentially with increasing speed. Vibration is more severe than before, especially at the roll nip. At present, the obstacle in many paper and board forming machines is the vibrating roll. It is simply necessary to run the paper and board forming machine slowly so that the vibration does not increase to harmful levels.

  Today, roll shells of paper and paperboard forming machines are manufactured by casting or bending steel sheets. The shell is rounded by machining and, if necessary, it is provided with a machined groove and covered. However, the roll lacks special braking against vibrations and instead the braking is simply based on the inherent properties of steel or casting.

  The composition on the roll surface is not included in the damping, but damping is done elsewhere. If it is desired to minimize vibration, especially in the nip, the surface material of the roll has virtually no significance.

  In practice, especially elastic materials such as rubber and the like tend to generate vibrations on the outer surface of the roll rather.

  It is an object of the present invention to provide a braking arrangement which can generate efficient braking especially for the two mechanical roll vibration types mentioned above, namely the beam vibration of the roll and the peripheral vibration of the roll.

  The invention provides that the braking arrangement additionally comprises at least one essentially rigid inner shell and a braking structure disposed between the shell and the inner shell, the inner shell being spaced from the inner surface of the shell. Arranged radially in the roll and essentially coaxial with the shell, the outermost surface of the brake structure being arranged immovably relative to the inner surface of the shell, and the innermost surface of the brake structure being By being placed stationary with respect to the outer surface, the forces caused by the difference in motion between the shell and the inner shell during the roll vibration period are converted into shear forces in the braking structure, which are in the braking structure. It is characterized by being essentially extinguished.

  Preferred embodiments of the invention are described in the dependent claims.

  Thus, the braking arrangement according to the invention comprises two essentially rigid shells and a damping structure arranged between them. As a result, the difference in motion generated due to the bending of the two rigid shells is converted into shear forces, which are then extinguished within the manufacturing structure. The braking structure can be composed of a damping material, whose stiffness characteristics are essentially lower than the stiffness characteristics of the roll shell and the inner shell. When a rapidly returning stress is introduced into this type of flexible material with high internal friction, the stress essentially disappears. On the other hand, it is possible to use intermediate structures that convert as much stress as possible into shear forces.

  According to the present braking arrangement, preferably a braking element is first formed which comprises an essentially rigid inner shell and a damping braking layer arranged on the outer surface of the inner shell, and this braking element Can be mounted inside the roll to be totally braked. An important feature of the solution according to the invention is the stiffness difference between the roll shell and the inner shell, such that the maximum possible stiffness of the roll shell and the inner shell and the stiffness of the shell is higher than the stiffness of the inner shell. This provides the maximum shear force between the shells for shell motion. Thus, according to the invention, the inner surface of the braking element, i.e. in this case the inner shell, is also rigid and continuous. Thus, the inner shell should be rigid so that deflection occurs particularly in the damping material. It is the work of the damping material, not the work of the shell, to create and extinguish the shear stress.

  Another important feature of the present invention is the maximum thickness of the braking layer. In other words, it is the maximum possible distance in the roll radial direction between the targeted shell and the inner shell. That is, it has been discovered that the thickness of the braking layer directly correlates with the damping capacity of the braking element. This is due in particular to the fact that the greater the mutual distance between the shells in the roll radial direction, the greater the motion difference between them during the roll oscillation period. When the motion difference is large, the mechanical stress also increases between the shells connected through the damping layer. The stress again generates a shear stress in the damping layer. Within the braking layer, these rapidly returning shear forces are extinguished, and thus the vibratory motion of the roll is braked.

  Essentially, the braking properties are directed to the braking layer so that maximum braking is achieved in the longitudinal direction of the roll and in the tangential direction around the roll. More specifically, the damping material has a maximum stiffness both in the longitudinal direction of the roll and in the tangential direction around the roll.

  In practice, rubber has been found to be the best possible braking material in the braking layer. However, other materials can also be applied to the solution according to the invention. For example, polyurethane having a light weight and high internal friction is also applicable as a material for the braking layer. Various elastomers can also be used.

  Other advantages are also achieved using the solution according to the invention. First, it is applicable to both current and new roles. In other words, the braking element can be suitably and completely formed even before it is brought into the roll to be braked. The braking layer is first mounted on the outer surface of the inner shell, the outer surface of the braking layer is exposed to processing for fastening to the inner surface of the outer shell, and finally the braking element thus formed is rolled Guided inside, where the outer surface of the braking layer is attached to the inner surface of the shell.

  In this way, the braking element can be fitted directly to the inner surface of the shell as a finished product. The braking arrangement according to the invention can easily be adapted for various sized rolls. This type of modular construction is particularly advantageous for older rolls. On the other hand, this arrangement can be adapted to all nip rolls and processing rolls.

  Because of the structure, it is also possible to avoid additional transverse seams, thus improving the durability and strength of the structure. In addition, it is possible to fit several adjacent braking elements within a single roll, each extending only for a part of the distance in the longitudinal direction of the roll.

  The invention will now be described with reference to the accompanying drawings, which illustrate some embodiments of the invention.

  FIG. 1 is a cross-sectional view of a roll 1 in which damping is performed using a braking structure 4 formed by an inner shell 3 and a braking layer 4 ′. The braking structure is a braking element 13 that conforms to the dimensions of the roll 1 to be braked and can be guided entirely inside the roll 1. The outer surface of the braking layer 4 ′ is pressed against the inner wall 10 of the shell 2 by applying a sufficient force for fastening, for example, using the turnbuckle screw 6 shown in FIG. 1. This is better illustrated by the cross section of the roll 1 shown in FIG. The surfaces of the braking layer and the inner shell 3 are fixedly attached to each other. The surface can be attached by adhesion or vulcanization. After stretching of the inner shell, it is formally locked, for example by means of a longitudinal weld 7.

  The deflection of both the shell 2 and the inner shell 3 should be as small as possible. During the vibration period of the roll 1, the shell 2 and the inner shell 3 tend to bend in response to the vibration, but bend in various ways because of their different structure. As a result, the shear forces generated by the stresses caused by the differences in motion are transmitted to the braking structure 4, where they are removed and thus damped. Damping of the roll 1 is best when the distance between the shell 2 and the inner shell 3 in the radial direction of the roll and thus their mutual motion difference is as large as possible.

  Thus, what is essential for braking is the thickness of the braking layer, whose maximization is targeted. This is exactly to achieve a large motion difference between the shell 2 and the inner shell 3. The ratio of the thickness of the braking layer 4 ′ to the thickness of the shell 2 is preferably 6 to 60%, more preferably 30 to 50%. In the embodiment of FIG. 1, the optimized thickness of the braking layer 4 ′ is 50 mm.

  Another important feature in the braking structure is the high stiffness of the shell and the inner shell, and the stiffness difference between the shell and the inner shell. When the roll tends to vibrate, this results in maximum shear between the shells. The ratio of the thickness of the inner shell 3 and the shell 2 is 1-10% grade, preferably 3-6% grade. In one embodiment of the invention according to FIG. 1, the thickness of the shell 2 is configured to 120 mm and the thickness of the inner shell 3 is configured to 5 mm.

  In the solution according to the invention, the goal is to preferably optimize the braking characteristics of the braking layer 4 'for both ambient and beam-like vibrations. This is also taken into account when forming possible holes or openings in the damping layer. In this case, a net-like structure is targeted for the braking layer. The holes are configured such that, with respect to their shape and size, the damping layer has a maximum stiffness in the longitudinal direction of the roll and in the tangential direction around the roll. This makes it possible to maximize the capacity of the braking layer for damping in these directions.

  In FIG. 1, the rubber mat forming the braking layer 4 'is provided with holes 5, which in this embodiment extend throughout the braking layer 4'. The actual purpose of the hole 5 is to reduce the mass of the braking layer. It should be noted that the mass of the braking material has no significance with respect to the braking efficiency itself.

  If only one continuous braking element is placed in the roll, it should essentially extend the entire length of the roll, as shown in FIG. This provides efficient vibration control. In addition, it should be noted that the inner shell 3 is open at both ends and is separated from the head component of the roll 1. However, it is also possible to use two or more separate braking elements that extend only over some distance in the longitudinal direction of the roll inside one roll. In this case, braking is particularly directed to ambient vibrations. If several elements are used that extend only part of the distance in the longitudinal direction of the roll and are essentially separated from each other, each element will dampen within a certain frequency range. Thus, if desired, each element can be arranged to accurately brake within a specific frequency range. Of course, in this case, the braking is also directed to the beam-like vibration of the roll, but the braking is not efficient. If it is desired to achieve efficient braking of beam-like vibrations when using several braking elements within one roll, the elements must be configured in series with each other.

  Specifically, if the material used for the braking layer is polyurethane according to one embodiment of the present invention, the braking element can be easily injected into the shell, even at the mounting location. It should be noted that with the arrangement according to the invention, the attachment of the braking layer and the inner shell inside the roll can be accomplished naturally even at completely different stages.

  According to another further embodiment of the invention, the balancing is performed by arranging balancing elements on both sides of the braking element instead of the balancing ring commonly used in roll balancing. It is also possible to do.

  On the other hand, in so-called tube rolls, balancing is now performed using polyurethane compositions. The polyurethane composition is injected on the inner surface of the roll shell every quarter of the roll at a time using a net grid. According to another further embodiment of the invention, the balancing net and polyurethane composition can be replaced, for example, with two braking elements, and a separate balancing element can be positioned in relation to the braking element.

  FIG. 3 shows a cross-sectional view of a roll 1 having two braking elements 13 according to the invention. Both braking elements 13 have the above-described inner shell 3 and braking structure 4. Here, however, the braking structure 4 consists of an intermediate structure 8 connected to the inner surface 10 of the shell 10 and / or the outer surface 11 of the inner shell 3 using a braking component 9 made of braking material. The intermediate structure is used to convert stress into shear force, which is effectively damped in the braking component. In the left braking element 13, a ring-shaped braking component 9 and an intermediate structure 8 are used. Functionally similar elements are referenced using the same reference numbers. The ring-shaped component is easy to manufacture and install. In addition, they provide the roll with good hardened steel, but braking is reduced primarily due to the reduced amount of braking material and shear forces. A longitudinal intermediate structure can be used to add the damping material, which is shown on the right side of FIG. Here, the braking element 13 is disposed at a point at a distance of a quarter length of the shell from both ends of the shell 2. This positioning provides excellent braking against beam-like vibration with a relatively small braking element. According to the invention, the length of the inner shell 3 is in this case 500 to 2000 mm, more preferably 1000 to 1500 mm. Similar braking elements can also be used in non-rotating structures such as doctor beams.

  4a is a cross-sectional view of FIG. According to the invention, the intermediate structure 8 consists of one or more profile components 12. In addition, the profile component 12 includes at least one portion that deviates from the radial direction of the roll 1. This structure converts more than 90% of the stress caused by the motion difference into a shear force. Thus, the braking material works optimally and provides good braking. At the same time, a thin braking component that reduces the total mass of the braking structure can also be used. According to the invention, the thickness of the braking component is 5-30% between the shell and the inner shell, more preferably 10-20%.

  FIG. 4b shows a partially enlarged view of FIG. 4a. Here, two different thicknesses of braking components are used. The outermost braking component is primarily intended to attach the profile component 12 to the inner surface 10 of the shell 2. Instead, the innermost braking component is thick to provide sufficient braking. In addition, the profile component has an inclined section, so that the stress caused by the mutual movement of the shell is converted into the shear force of the braking component. In this embodiment, the inclined section forms an angle of 45 ° with the roll radius. In addition, the thickness of the shell and inner shell is 90 mm and 5 mm, respectively. The innermost braking component is 10 mm thick. The braking component is preferably an elongated section attached to the profile component. On the other hand, the braking component may be, for example, square pieces placed at appropriate intervals in the longitudinal direction of the profile component. Other forms of braking components can also be used.

  Thus, the inner shell can be formed from a sheet material. In addition, according to the invention, only one profile component is used which is likewise formed from a sheet material. In this case, for example, laser cutting or welding can be used to achieve dimensional and profile accuracy of the inner shell and profile components. In the proposed embodiment, the thickness of the profile component is 2 mm. The plate and material thickness are dimensioned based on requirements and application. In the proposed embodiment, the longitudinal cells are formed into a roll and can conduct media therethrough to adjust the roll temperature. On the other hand, the medium can act as a damping material as far as it is concerned.

  In the braking structure according to FIGS. 5 a and 5 b, compared to the solution illustrated in FIGS. 4 a and 4 b, there are additional hardening rings 16 and tension screws 15, each tension screw being a rib 16 included in the hardening ring 16. 'Installed in. Again, the intermediate structure 8 couples the inner shell 3 to the shell 2. The braking component 9 is fastened, bonded, or screwed to the inner and outer surfaces of the corrugated plate included in the intermediate structure 8. The braking component is made of elastomer or rubber, for example, and its layer pressure is about 10 mm. The corrugated plate with the braking component is stretched with respect to the outer shell using, for example, the above-described curing ring. Thereafter, the corrugated plate of the intermediate structure 8 is integrally welded in the longitudinal direction.

  Next, the blank of the inner shell 3 is brought into the intermediate structure 8 and the blank is stretched in place using the tension ring 15 located on the curing ring 16 and the rib 16 'of the curing ring. The inner shell 3 is also welded to produce a continuous form. The tension screw 15 is used to pull and center the braking structure at a predetermined position, and the entire structure is held at a predetermined position by using a tension screw pre-tension system. Adhesion can also be used if desired. This structure makes it possible, for example, to circulate water inside the roll. The distance between the curing rings is about 35% (± 10%) of the inner shell diameter.

  The above-described structure provides better braking than just a braking layer (FIG. 1), both computationally and on field tests. In general, good braking requires both a successful mechanism and a good braking medium. In this embodiment, the mechanism can convert as much as 96% of the roll vibration into an elastomeric shear force. For example, rubber has a good braking ability.

  The manufacturing method of the inner shell 3 is clear from FIG. 6, and both ends of the blank bent into a cylindrical shape are provided with finger joints. The blank of the inner shell 3 has cuts 18 or protrusions 19 that alternate over the seam length at both ends of the periphery. Unlike a straight abutment joint, when both ends can move relative to each other, this provides a reasonable tolerance for the dimensional accuracy of the blank. As soon as the blank of the inner shell 3 is stretched in place, welding the projection 19 to the notch 18 at the opposite end can provide a seam that joins the ends.

  The braking structure according to the present invention is easy to implement and can be used with various rolls. In addition, it is possible to produce special braking elements that can even be retrofitted to existing rolls. Furthermore, it is possible to utilize a thin plate technique that simplifies the production of the production structure according to the invention. However, what is essential is the formation of motion differences between structures and the conversion of stresses caused by them into shear forces, which are extinguished in the damping material. The rolls according to the invention can be used, inter alia, as nip rolls such as, for example, application rolls, calendar rolls, cutter king rolls. Non-nip applications are, for example, calendar diffusion rolls and shrink rolls.

It is sectional drawing which shows a roll provided with the braking structure according to this invention. It is sectional drawing of the roll of FIG. 1 which follows the cutting line AA. It is sectional drawing which shows the other embodiment of a roll provided with the braking structure according to this invention. It is sectional drawing of the roll of FIG. 3 which follows the cutting line BB. FIG. 4b is a partially enlarged view of FIG. 4a. FIG. 4b is a partial cross-sectional view showing a modification of the braking structure of FIG. 4a. FIG. 5b is a partial cross-sectional view showing the structure of FIG. 5a. It is the schematic which shows the manufacturing method of the inner shell of the roll according to this invention.

Claims (16)

A braking arrangement for damping mechanical peripheral vibrations and beam-like vibrations of a roll comprising an essentially rigid shell in a paper or paperboard forming machine,
At least one essentially rigid inner shell and a braking structure disposed between the shell and the inner shell;
The inner shell is spaced apart from the inner surface of the shell and arranged in the radial direction of the roll, and is essentially coaxial with the shell;
The outer surface of the braking structure is disposed immovably with respect to the inner surface of the shell, and the inner surface of the braking structure is disposed invariably with respect to the outer surface of the inner shell,
During the vibration period of the roll, the force caused by the difference in motion between the shell and the inner shell is converted into a shear force in the braking structure, which essentially disappears in the braking structure. Brake arrangement characterized by being made.   The braking arrangement according to claim 1, characterized in that the braking structure comprises a braking layer made at least partly of a damping material.   The braking arrangement according to claim 1, characterized in that the braking structure comprises an intermediate structure connected to the inner surface of the shell and / or the outer surface of the inner shell by a braking component made of a damping material.   4. Braking arrangement according to claim 2 or 3, wherein the damping material is rubber, polyurethane or the like.   In order to brake peripheral vibrations and / or beam-like vibrations, the braking characteristics of the braking structure are optimized in the tangential direction around the roll and / or in the longitudinal direction of the roll, The braking arrangement according to any one of claims 1 to 4.   The braking arrangement according to claim 2, wherein the braking layer has an opening or a through hole in order to reduce its mass.   The ratio of the thickness of the braking structure to the thickness of the shell is 6 to 60%, more preferably 30 to 50%, according to any one of the preceding claims. Braking arrangement.   The brake layer and the brake component are attached to the inner surface of the shell and the outer surface of the inner shell by adhesion, vulcanization, or a similar method. Braking arrangement as described in   Braking arrangement according to any one of the preceding claims, characterized in that the thickness of the inner shell is 1-10%, more preferably 3-6% of the thickness of the shell.   4. Braking arrangement according to claim 3, characterized in that the intermediate structure consists of one or more profile components including at least one component deviating from the radial direction of the roll.   4. Braking arrangement according to claim 3, characterized in that the thickness of the braking component is 5-30%, more preferably 10-20% of the distance between the shell and the inner shell.   12. Braking arrangement according to any one of the preceding claims, characterized in that the braking arrangement is formed over essentially the entire length of the shell.   The braking arrangement according to any one of claims 1 to 11, wherein the braking arrangement is formed at two or more points spaced apart from each other in the longitudinal direction of the roll.   14. Braking arrangement according to claim 13, characterized in that the point is essentially a distance of one quarter of the length of the shell from both ends of the shell.   15. Braking arrangement according to claim 13 or 14, characterized in that, at the point, the length of the inner shell is between 500 and 2000 mm, more preferably between 1000 and 1500 mm.   In the braking arrangement, the inner shell and the braking structure are arranged as a retrofitting braking element, and the retrofitting braking element is configured to be fastened to the inner surface of the shell. The braking arrangement according to any one of the preceding claims.

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