FI118435B - Arrangement for balancing the roll of a fiber web machine - Google Patents

Description

118435 Arrangement for balancing a roll of a fiber web machine

The invention relates to an arrangement for balancing a roll of a fiber web machine in which the center of mass distribution, i.e. the center of mass, of the mass distribution relative to the axis of rotation of the roll is changed to obtain a true center of mass at a desired distance from the center of rotation.

To observe the mass distribution, the roll can be subdivided from the center of rotation into n into a sector where n * da is 360 °. At a portion of the roll rotation angle, at a distance da, there is a mass dm that is at a distance dr from the center of rotation of the roll. The mass dm and and the distance dr of the mass dr from the center of rotation 10 may not be the same in all sectors Dai, da2, ... dan. The center of mass of a roll cross section is obtained when all sectors of the roll are considered together. Said predominant mass distribution is generated or caused to the roll, for example, as a result of the manufacture of the roll, the roll being in the fiber web machine due to changes in conditions, or a corresponding change in some parameter affecting the roll, such as wear.

The peripheral speed of rolls used in fiber web machines such as paper machines, paper finishing machines, calendars, winders and the like typically corresponds to the speed of the fiber web being produced. Fiber web production speeds vary considerably but the trend is towards higher production speeds 20 and, for example, 3000 m / min or 50 m / s fiber web speeds are no longer unusual • · ·: · *, especially in nonwovens. The diameter of the roll determines the speed of rotation, which, for example, would then be about 53 l / s or 3183 "** · 1 / min on a 300 mm diameter roll. When rotating at such a speed, the roll, if unbalanced, causes vibration that strains and rolls itself: 25 machine structures, including buildings, and the fiber produced ···: ***: At least, there is unwanted vibration when a single roller vibrates, but nip, As the forming roll oscillates, the fiber web is also subjected to uneven compression, • at its worst, it causes a marked change in the thickness and wedge *: ** 30 to and even breaking of the web.

• · • · * * ··. ···! To solve this problem, the rolls of nonwoven machines are rebalanced to the accuracy required for each precision position • · "S position. Conventionally, the reels of nonwoven machines are rebalanced at the manufacturing or maintenance stage" **: disconnected from the weaving machine. The work is performed on a separate balancing machine 35 or on a roll lathe which includes balancing means. However, the operating conditions of the roller may be significantly different from those of the roller workshop. There is usually a significant difference between the environmental conditions affecting the roll and the temperature. In industrial use, for example, the temperature of a 1500 mm diameter thermal roller acting on the fibrous web by heat can be 250 ° C. If the bearing spacing on such a roller is, for example, 12 meters, at 250 ° C the bearing spacing is almost 30 mm longer and the diameter nearly 4 mm larger than what the roller spindle at 25 ° C. This will of course have some effect on the balancing of the roll and the distance of the true center of mass from the actual center or axis of rotation of the roll. Typically, balancing is accomplished by adding mass, such as a metal bar, to the main working area of the rolls. The insertion is made at such positions that the displacement of the center of mass relative to the center of rotation caused by factors in the roll structure can be compensated. The roll is a rotating body about its axis, so that it can advantageously be viewed as a function of the roll rotation angle.

15 Rolls used in fiber web machines are typically made of metal, such as steel or cast iron, and the latest developments are various cellular metal rolls. Rolls of plastic composite construction are also commonly used in fiber web machines. The requirements of modern fiber web machines for rolls are that one of the almost indispensable work stages of roll manufacture 20 prior to roll-in is the balancing process, although manufacturing methods are constantly being developed with the aim of more balanced and improved roll blanks.

As an example, a conventional steel sheet "I" *. Bend, which after turning is turned to the correct wall thickness and circular. This turning is problematic for balancing. ··· * 25 step, especially in the form of external turning, to initially change the wall thickness of a sheet of material of constant thickness.

· · ·

The accuracy of the geometry provided by the bending of the blank preform depends on how large the thickness variations become in the turned roll shell. These thickness variations: besides geometric errors, are the most common factors causing roll imbalances: ***: 30. Turning such a sheet-bent roll blank also on the inside ···. ·. the problem can be reduced. Due to setup accuracy and other similar sources of error, · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Similar phenomena occur in casting rolls: then the quality of the molds and mold installation is crucial.

··· # 35 The varying material thicknesses described above cause changes in equilibrium even when the temperature changes between the temperature of 118435 3 at the manufacturing or equilibration stage and the operating temperature. Changes in temperature also affect the stress state of the roll, which may cause changes in equilibrium, for example due to creep.

Patent FI 98404B discloses a method for compensating for measured or calculated bending-stiffness or unbalance of a roll by making longitudinal grooves or pockets of the roll in the roll body.

It is an object of the invention to provide an arrangement for balancing the roll, whereby the balancing of the roll is maintained within the target values under various operating conditions, in particular as the temperature changes. Particularly, an arrangement is provided which allows the balancing of the roll to be altered without removing it from the fiber web machine. It is also an object to enable the roll of a fiber web machine to be balanced at various speeds of the fiber web so that the balancing state can be easily changed according to the desired speed range while still maintaining a sufficiently low vibration level. It would also be advantageous that this could be done during a change of condition, for example during the ramp-up sequence of a fiber web machine, while simultaneously changing the production speed or temperature of the fiber web machine or both.

The invention is characterized in that at least one end of the roll has at least one balancing element which is rotatable about an axis of rotation and whose center of mass is displaceable in the radial direction of the roll.

By means of the invention, the object of the invention is achieved, the balancing of the roll can be adjusted to *: · possibly meet the changed need without being removed from the fiber web machine.

· · · «*: ·· · Similarly, the driving characteristics of the roller are easily adapted to the conditions.

. * ··. An example of such a possible change is the different types of fiber web machine • ·. . ·. process changes such as changes in roll temperature or running speed.

The invention may be implemented by one or two or more balancing elements. If one balancing element is used, i.e. the number of balancing elements is one, the center of mass of the balancing element is rotatable about the axis of rotation and displaceable in the direction of the roll radius. The invention ·· *. according to another embodiment, when the number of balancing elements is *; ./ 30, two or more balancing elements are centered at the center of mass and are rotatable about the axis of rotation. Thus, in the latter embodiment, it is sufficient that the balancing elements are twisted ·: ··; rotatable around the axis of rotation. Of course, radial displacement can also be accomplished in this case, but even without it, the common center of mass of the balancing elements can be displaced to the desired position.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a simplified diagram of the vibration behavior of two rolls, Fig. 2a is a cross-sectional view of the roll, illustrating the operation of the balancing elements in one setting, Fig. 2b 2a relative to the situation, and FIG. 3 shows a conventional way of performing roll balancing.

Figure 1 shows the peripheral speed of the roll on the horizontal axis and the force or amplitude caused by vibration on the vertical axis. Rolls A and B are balanced for different design speeds, roll A for speed vi and roll B for speed V2. The horizontal line G represents the maximum permissible oscillation of the roll, that is, in practice, the maximum value of the balancing factor of the rolls in question. Roller B with a higher design speed V2 does not meet criterion G during ramp-up. Such a situation may cause problems during ramp-up or when driving production at a speed lower than the design speed, such as when producing the heaviest types of non-woven fiber that can be produced by the fiber machine. The arrangement according to the invention provides a solution to this problem, since the balancing of the roll is adjustable due to the need for modification. as required by the changed circumstances. Such conditions may include, in addition to a change in the basis weight of the fibrous web produced, a change in the operating temperature, for example. The velocity affects the equilibrium mentioned in ... *, that at different speeds the characteristic female oscillation of the cylindrical long roll • 25 is slightly different and the mass distribution may not be exactly the same. It is preferable that the position of the center of mass * · · 50 of the roll 1 is measured directly or indirectly. Suitable means for this purpose include, for example, acceleration or force sensors and the like.

«• · · 1 · *

Fig. 2a shows a situation in which the rotation angle β between the balancing element 10 and the balancing element 20 is 180 °, whereby the center of mass 30 of the balancing elements * · is not changed from the geometric center of rotation 40 of the roll.

The center of mass 11 of the balancing element 10, the mass: * ·, the center 21 and the center or axis of rotation of the roller and the unbalanced · · 't \ center of mass 50 of the roller 1 are on the same straight line. rotation axis 40 of roll 1.

118435 5

Fig. 2b, in turn, shows a situation where the unbalanced center of mass 50 of roll 1 is in the direction a + 180 ° from the rotation center 40 of roll 1. Any point on the roll can be selected as a zero. In order to balance the mass center 50 of the roll 1 5, i.e. displace it to the same position as the rotation center 40, the balancing element 10 and the balancing element 20 are set to compensate for this deviation. The balancing element 10 and the balancing element 20 are at a rotation angle β of 90 degrees with respect to each other, whereby the center of mass 30 of the balancing elements 10, 20 is at a distance? based on the oscillation information, programmatically adjusts the rotation center 40 or the desired distance from the actual rotation center or axis. Thus, by varying the rotation angle β of the balancing elements and by changing the rotation angle α between the balancing elements and the roll, the eccentric balancing elements are oriented in a freely selectable direction around the roll circumference while the desired center of mass distance from the axis of rotation is obtained.

Figure 3 illustrates one prior art method of balancing roll 1. 20 There are four fixing points 9 of the balancing element or mass at the end of the roll 1, at which, at the balancing machine, suitable masses 10 are fitted to compensate for any imbalance.

• - «" **. According to one embodiment of the invention, it is also advantageous for said balancing element 10, 20 to be movable with respect to the axis of rotation 40 while the roller 1 · · ** · · 25 is rotating, particularly preferably during the ramping and production run of the fiber web machine.

* ··· ** This software adjustment of the balancing elements requires the use of a suitable actuator to change the position of the elements. Such actuators suitable for this purpose include, but are not limited to, stepper motors, spindle motors and the like, which are capable of precise adjustment. The required positioning accuracy is a foot-30 rose range of 0.5 ° depending on the subject, meaning in some applications this ··· J. a better solution, but somewhere else, coarser resolution will suffice. The balancing elements are also preferably lockable in their selected position independently of said actuator. In this case, the misalignment of the set adjustments is likely to be very small ····· 35 Because fiber rollers today easily have roller lengths of more than ten meters, the center of rotation or axis of the cross-section is not necessarily a “118435 geometric straight curve. In such cases, the balancing may well be facilitated by an arrangement in which, in addition to the balancing elements 10, 20 at each end of the roll 1, such balancing elements according to the invention and their adjustment means 5 are provided. In the context of this invention, about a% of the length of the roll shell from the end is considered to be the end region and the region between them is considered to be the middle region.

·· 1 • »• · • ·» 2 3 ···· • ** «• · * · · · · · · · · · · · · · · · · · · · ··· aa «* 1 • 1 • · a • · • · i · 1 • · • 1 1 • · • · 2 • · * • 1 • · · · 3 · 118435 7

Reference numerals and symbols used in the drawings: 1. roll 9. attachment point of the balancing element at the end of the roll 10. balancing element 5 11. center of mass of balancing element 20. center of mass 21 of balancing element 30. common center of rotation 10 or center of rotation 50 of balancing elements 10 and 20 unbalanced center of mass e of roll 1 distance between points 30 and 40 f distance between points 40 and 50 a direction of rotation of common center of mass of balancing elements 10 and 20 15 β rotation angle of balancing elements 10 and 20 ··· · · · · · · · · · · ········································································ · · · · · · · · • · ♦ • ·· • · ··········································································· · · ·

Claims (9)

An arrangement for balancing a roller (1) a fiber web machine, in which arrangement the center of gravity (50) of gravity (50) relative to the axis of rotation (40), i.e. mass center (bary center) (50) is changed to obtain an actual mass center at the desired distance from the center of rotation (40), characterized in that at least at one end of the roller there is at least one balancing element (10, 20) which can be rotated about the axis of rotation (40) and whose center of mass (11,21,30) can be moved in the radial direction of the roller (1). Arrangement according to claim 1, characterized in that when the number of balancing elements is one, the center of mass (11) of the balancing element (10) can be rotated around the axis of rotation (40) and moved in the radial direction of the roller (1). 3. Arrangement according to claim 1, characterized in that if the number of balancing elements is two or more, the balancing elements (10, 20) with respect to their center of mass (11, 21, 30) are eccentric relative to the axis of rotation (40) and can be rotated about the axis of rotation ( 40). Γ \: Arrangement according to claim 1, characterized in that said balancing element (10, 20) can be moved relative to the axis of rotation (40) while the:: ··: roller (1) rotates, advantageously when raising the fiber web machine and below. production operation. »* · Arrangement according to claim 1, characterized in that there are balancing elements (10, 20) at each end of the roller (1). ·. 25 Arrangement according to claim 1, characterized in that said balancing element (10, 20) can be rotated 0 - 360 ° about the axis of rotation of the roller (1) (40). • · • · · • · · * «· ·. ···. Arrangement according to claim 1, characterized in that the position of the center of mass of the roll (50) is measured directly or indirectly. • · • · ··· ·: · ♦ · 30 Arrangement according to claim 1, characterized in that in addition to the end zone of the roller (1), balancing elements (10, 20) are in the middle zone of the length of the roller (1). 118435 Arrangement according to claim 1, characterized in that the eccentric balancing elements can be directed by changing the angle of rotation (β) between the balancing elements (10, 20) and by changing the angle of rotation (a) between the balancing elements (10, 20) and the roller (1). (10, 20) in a freely selectable direction on the mantle surface of the roller (1) at the same time as the distance of the center of mass (30) from the axis of rotation can be freely determined. · ♦ • · · · · · · · - · «« ·· • · ··· • · · · · ♦ ♦ • · · · · · · · 1 · 1 «• · • · •« · • 1 • · • · ♦ * ♦ · 1 · · · · · · · · · · · ♦ · · · 1 · · · · · · ♦