FI94458C - Procedure in the rolling operation of a paper machine and plant for the process - Google Patents

Description

94458

Method in the use of a paper machine and equipment according to the method Förfarande vid valsdriften av en pappersmaskin och anläggning för förfarandet 5

The invention relates to a method for using a paper machine in a roll and to an apparatus according to the method.

10 As the speeds of the paper machine increase, the diameters of some rolls have to be increased due to the critical rotational speed of the rolls. The increase in the diameter of the rollers is again hampered by the increase in costs, the need for space increases and the natural frequency of the entire structure may enter an unfavorable area.

15 This application discloses a method and apparatus solution that can avoid running a roll at critical speeds. In the invention, the critical speed is changed by changing the mass of the roll, and / or the stiffness and / or the support point of the roll. For example, by changing the stiffness of the roll in the blink of an eye, a supercritical range can be driven. The new roll support can be left permanent or returned to the original. The same method 20 can also be used to bypass the semicritical speed.

The critical speed of the roll can be affected, for example, by changing the stiffness of the roll end plate coagulation. This can be done, for example, by means of a separate hydraulic actuator. The cylinder device presses the rigid base material against the base plate. In this case, the support of the 25 rolls is made considerably stiffer and with it the critical speed of the roll is changed.

The critical speed can also be affected by changing the mass of the roll. This can be done, for example, by pumping liquid inside the roll and vice versa.

30

The critical speed can also be affected by changing the position of the roller bearing.

2 94458

The method and apparatus according to the invention are characterized by what is stated in the claims.

The invention will now be described with reference to some preferred embodiments of the invention shown in the figures of the accompanying drawings, to which, however, the invention is not intended to be exclusively limited.

Figure 1A shows the rotational speed of the roll in the horizontal coordinate system and the oscillation amplitude of the roll in the vertical coordinate system. υ KR = critical speed (natural frequency) 10 xh υ KR = semi-critical speed (natural frequency)

Fig. 1B shows the first step of the method according to the invention, in which the speed of rotation of the roll has come close to the critical speed of the roll.

Figure 1C shows the step of the method according to the invention, in which the support of the roll has been changed and the critical speed of the roll has been calculated by the change of the support. In this way, the critical speed has been exceeded and the speed of the roller can be increased to the actual driving range.

In Figure ID, the roll support has been restored again, but the roll speed is already 20 safely above the critical roll speed.

Figure 2A shows a method according to the invention in which the position of the oscillation peak is changed permanently. Fig. 2A shows an initial situation in which an increase in vibration is observed, e.g. on the basis of a vibration measurement.

25

Figure 2B shows the change in the position of the vibration peak, where the driving range is above the semi-critical speed.

Figures 3A-3C show the dependence of the term Xj on the method of attachment and the order number of the eigenfrequency 30. In the case of Figure 3A, the beam is supported at both ends 3 94458 so that the vertical displacement of the beam is prevented but an angle change is allowed for the beam.

Fig. 3B shows a case where the attachment of one end of the beam is completely rigid and the attachment of the other end 5 allows an angular change but in which the vertical displacement of the beam is prevented.

In the case of Figure 3C, the beam is rigidly supported at both ends.

10 Figure 4A considers the effect of the support spring constant on the eigenfrequency. Figure 4A shows a support in which an angle change is allowed for both ends of the beam, but in which the end displacements of the beam are prevented when the ends of the beam are completely rigidly supported.

Figure 4B otherwise shows a case similar to Figure 4A, but the beam is resiliently supported at both ends.

Figure 5A shows the adjustment of the torsional stiffness of the beam end support with an adjusting screw.

20

Fig. 5B shows another embodiment in which tilting of the end shaft is allowed, but in which the stiffness of the tilt is adjusted by turning the screws.

Fig. 6 shows a support otherwise corresponding to Fig. 5A, but the adjustment of the spring constant 25 takes place by means of a cylinder device.

Fig. 7 shows a solution otherwise similar to Fig. 6, but the rigidity of the support is changed by means of a screw device. The screw is passed through the bearing housing cover to the base.

30 4 94458

Figure 8A shows a cross-section in a bearing comprising a resilient material between a bearing and a bearing housing. The stiffness of the bearing support can be changed from outside the bearing, for example by means of a screw device, by moving the support device. The bearing can thus be supported either by a flexible material or by more rigid movable support devices 1a.

5

Figure 8B is a section I-I in Figure 8A.

Figure 9 shows in principle an embodiment of the method according to the invention, in which the critical speed is influenced by changing the mass mj of the roll.

10

Figure 10 shows an embodiment of the invention in which the support distance of the roll is changed.

Figure 11 shows an embodiment in which the critical speed is affected by bringing a temporary support roller into contact with the roll.

15

Figure 12 shows the locking of the flexible beam to the stiffer lower beam with a separate support piece.

Figure 1A illustrates the running areas of the roll. Problems occur in driving situations when driving in zone 1 at half the critical speed (υ 1/2 KR) or when passing zone 1, ie at semi-critical speed (υ 1/2 KR). There are also problems with prior art applications when driving in zone 3, i.e. the critical speed range (υ KR) and when passing the critical speed (υ KR).

25 At present, the problems have been solved by not driving in areas 3 and 4 at all. In addition, the rollers are dimensioned large enough. Attempts have also been made to avoid problems by avoiding area 1, i.e. the semi-critical speed range. In this case, an attempt has been made to operate in area 0 or 2. This has been done by selecting the correct size roll or avoiding the semi-critical area 1. 1

The disadvantage of the above-mentioned uses is that the roll diameters become large and the construction thus becomes expensive.

5 94458 This application refers to the critical speed and semi-critical speed of a roll. One could also talk about the natural frequency of the roll and the semi-critical natural frequency. In the claims of this application, when referring to the critical speed of the roll, it generally means both, i.e. semi-critical and critical speed.

5

Figure 1B shows a roller drive according to the invention. Upon reaching the speed point Uj, the critical speed of the roll is changed, for example by changing the support of the roll. The roll support can be changed, for example, by changing the stiffness of the roll support.

Figure 1C shows the step in which the oscillation peak (υ KR) is displaced to the left in the blink of an eye, bypassing the critical speed and allowing the speed of the roll to be increased to the actual driving range. After the critical speed is exceeded, the stiffness of the support is restored. The same method can also be used to bypass the semi-critical speed.

15

In Fig. ID we are in the actual driving range and the stiffness of the support has been restored, whereby the critical speed (υ KR) is also the same as in the initial situation of Fig. IB.

Figure 2A shows another embodiment of the invention in which the driving range is at half-critical speed (υ 1/2 KR). In this case, the semi-critical speed of the roll is permanently given. As shown in Fig. 2B, during driving, the stiffness / mass / support of the roll / bearing or roll is not returned to the situation of Fig. 2A.

In the following, the eigenfrequency 25 of the bending oscillation of the roll is theoretically considered on the basis of Figs. 3A to 3C.

• *

The characteristic frequency can be calculated by the formula 6 94458 f = Xif £ 7 / <_ 2π ^ Μ £ 3 where E = modulus of elasticity of the beam I = moment of stiffness of the beam 5 M = weight of the beam L = length of the beam λϊ depends on the mounting method and the order of the characteristic frequency.

Fig. 3A shows an attachment of the beam in which an angular change is allowed at the ends 10 of the beam, but no displacement at the end of the beam, λ depending on the sequence number of the amine frequency is for the support; ^ i, 2,3 = 2π, 3ττ ^ 1,2,3 = 3,927; 7.069; 10,210 and relates to the beam attachment of Fig. 3B, in which an angle change is allowed to one end of the beam, but the other end of the beam is rigidly attached.

λ 1 2 3 = 4,730; 7,853; 10,996 relates to a beam support according to Figure 3C, in which both ends of the beam are rigidly attached.

20 Thus, stiffening the mount increases the natural frequency.

Thus, in the cases of aid described above, the natural frequency may even more than double as a result of the change in aid.

Based on Figures 4A and 4B, the effect of the support spring constant on the eigenfrequency is considered. In the case of Figure 4a, the support of the beam is rigid at both ends.

7 94458

f = J_ k_ II

2τΛ m where k is the spring constant m of the beam is an oscillating mass 5 In the case of Figure 4B, the end supports of the beam are flexible at both ends. The resultant spring constant is obtained as follows; 111

Who * 1 * 2 k2

jr = J_ * 1 * * 2 III

2π ^ (£, + k ^) m 10

That is, if kj = k ^ we get f = -L k1 '= J_ k' = -L y / 2 · - 2π \ (ifcj + fcj) m 2π ^ 2kxm 2π \ m, ie the natural frequency decreases by about 30% when equipping the ends of the roll with a flexible tuennal-15 Sat.

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The above is a very approximate representation for a roll. More accurate results are obtained, for example, by the transfer matrix method, in which the mass of the roll is divided into several points.

Figure 5A shows an apparatus solution for carrying out the invention. The spring constant of the support for the bearings 12a, 12b of the shaft 10a of the roll 10 can be varied to adjust the critical speeds (υ KR, υ ‘Λ KR) of the roll. The bearing housing 11 comprises bearings 12a, 12b, of which the second bearing 12a is supported by a flexible medium 14 arranged between the intermediate part 13 and 15. The intermediate part 15 is a wedge-shaped part which can be moved in the axial (x-axis) -10 direction of the roll by means of a screw device 16. The screw device 16 is passed through the hole P of the end 17 of the bearing housing 11. By turning the screw 16, the wedge part 15 (arrows S1 and S2) is moved and the spring constant of the medium 14 is affected. In an attempt to increase the critical speed / critical speeds, the intermediate material 14 together and in the opposite case part 15 is moved in the direction of arrow S2 direction.

15

Fig. 5B shows an implementation of a support according to the invention, in which the shaft 10a is supported by its bearings by means of an intermediate part 18 on the inner surface 22 'of the housing structure of the bearing housing 11. The intermediate part 18 comprises a spherical surface 19 supported against the housing structure 22. The intermediate part 18 is acted upon by some 20a12020a2. In the embodiment of the figure, the critical speed 20 is adjusted by means of screw devices 21 by adjusting the stiffness of the support. The screw 21 comprises threads 21aj, 21a2, one of which is right-handed and the other left-handed with respect to the center line Z of the screw. In connection with the screw 21 there are nut plates 21bj, 21b2. Thus, by turning the screw, the nut plate 21bj, 21b2 is moved in opposite directions and the springs 20aj, 20a2 are acted upon either by compressing them or vice versa. This affects the rigidity of the aid. 25

Figure 6 shows an embodiment of the invention in which the resilient element 23 is arranged between the base plate 11a of the bearing housing 11 and the body R. The cylinder device 24 is used to adjust the stiffness of the bearing. 1

As shown in Fig. 7, the stiffness of the bearing is adjusted with a screw 25.

9 94458

Figure 8A shows a resilient ring 26 built into the bearing housing. The resilient ring 26 is formed of a resilient material / structure that is compressible by means of screw devices 27a, 27b. By turning the screws 27a, 27b in the bearing housing 27c, the parts 29a, 29b in each adjusting part 5 can be moved away from each other by means of the wedges 27a, 27b in the adjusting part 5, thereby changing the rigidity of the bearing support. The shaft 30a and the bearing 10c are inside the spring ring 26.

Figure 8B is a section I-I of Figure 8A.

10

Figure 9 shows in principle an embodiment of the method according to the invention, in which the critical speed is influenced by changing the mass mj of the roll by pumping a liquid inside the roll, for example water, with a pump P and vice versa.

Fig. 10 shows an embodiment of the invention in which the critical speed of the roll is influenced by changing the position of the bearing 30 of the other end of the roll by moving the bearing 30 by the cylinder device 31 in the direction Lj.

Fig. 11 shows an embodiment in which the critical speed of the roll 20 is influenced by bringing a temporary support roller 32 in connection with the roll to rest on the roll surface 10 '.

Fig. 12 shows a solution in which the support of the roll 10 can be stiffened by means of an accessory 33. The roller 10 rests on a flexible cantilever beam 34. The accessory 33 comprises a cylindrical device 36 connected to the rigid beam 35, the piston rod 36a of which moves 25 the pivot bearing support 37 connected to the rigid beam 35 into contact with the flexible projection 34. By means of the arrangement the support of the roll 10 can be changed quickly.

Claims (17)

A method of rolling a paper machine, characterized in that, to prevent vibration of the roll at critical speeds, the location of the critical speed ranges (υ KR, υ 44 KR) of the roll is changed during the rolling of the roll. 2. A method according to claim 1, characterized in that the critical speed (υ KR, υ 14KR) of the roller is calculated and thereafter the speed of the roller is increased to the actual driving speed range. 10 3. A method according to the preceding claim, characterized in that the critical speed (υ KR, υ 'ΛKR) of the roller is then returned to the original. Method according to any of the preceding claims, characterized in that the critical speed (υ KR, υ 'ΛKR) of the roller is tilted for the time being during the driving situation of the roller. Method according to any of the preceding claims, characterized in that the critical speed (υ KR, υ '/ 4KR) of the roller is changed during the process by changing the stiffness of the support of the roller. Method according to any of the preceding claims 1-4, characterized in that the critical speed (u KR, υ '/ 4KR) of the roller is changed by changing the mass of the pulley. 25. Method according to any of the preceding claims 1-4, characterized in that the critical speed (υ KR, υ 'ΛKR) of the roller is changed by changing the location of the storage of the roller. 94458 Method according to any one of the preceding claims 1-4, characterized in that in the process the critical speed (υ KR, υ V KR KR) of the roller is changed by changing the spring constant of the storage of the roller. Plant used in a method according to any of the preceding claims 1-8, characterized in that there is a screw device (16; 21,22; 25; 27a, 27b) by means of which the flexible blank or structure is pressed together (14; 20a1,20a2; 20a1 ', 20a2,; 23,26) of the storage of the roller as it seeks to raise the critical speed of the roller and with the corresponding device, the compression condition of the blank or construction decreases as it strives to lower the critical (υ KR) , υ ViKR) speed. Installation according to the preceding claim, characterized in that there is a cylinder device (24) or a screw device (25) arranged between the lower plate (11a) of the bearing housing (11) of the roller (10) and the body (R). 11. An installation according to claim 9, characterized in that the screw device (16) or the like is arranged to move a source part (15), the flexible blank (14) or the structure being arranged between a counter source part (13) in connection with 20. the bearing (12a) of the shaft (10a) of the roller (10) and the movable wedge portion (15). Plant used in a method according to any of claims 1-8, characterized in that there is a pumping device (P), by means of which the mass of the roller (m 2 is increased to increase or decrease it), whereby The pulp mass regulates the characteristic vibration number of the drum. Plant used in a method according to any of the above claims 1-8, characterized in that there is a functional device (31) by means of which the bearing (30) of at least one end of the roller is moved to change the critical speed (self vibration number). 94458 Plant used in a method according to any of the preceding claims 1-8, characterized in that there is a movable support roller (32) by means of which the roller (10) is supported from its surface (10 ') for controlling the characteristic the vibration number of the roller. 5 Plant used in a method according to any of the preceding claims 1-8, characterized in that the roller shaft (10a) comprises a flexible ring (26) in connection with the bearing (10c) surrounding the bearing, which ring is actuated from outside with a screw device (27a, 27b). 10 Installation according to the preceding claim, characterized in that the screw device (27) is arranged to actuate parts (29a, 29b), whereby by twisting the screw in the bearing housing (27c) the parts (29b, 29a) are removed and pressed together flexible blank (26) and thus affect the stiffness of the bearing 15 by increasing it. Plant used in a method according to any of the preceding claims 1-8, characterized in that the bearing is supported against a flexible beam (34), wherein the stiffness of the flexible beam (34) is changed by a device (33) consisting of a rigid support beam (35) and a support piece (37) pivotally stored therewith, which support piece can be brought into contact with the flexible beam (34) with a functional device (36), coupling the flexible beam (34) ) at the rigid beam (35), thereby changing the rigidity of the roll support. 25