METHOD AND DEVICE IN THE REELING OF PAPER

Abstract: The web (W) is reeled by supporting the roll (30) from its outer circumference by means of at least two supporting units (10,20), of which the first one, in the direction of arrival of the web (W), is a carrier roll (10) provided with a mechanical rotating drive (10a), over which the web (W) is passed to reeling. The carrier roll (10) forms a reeling nip (10/30) supporting the roll (30) from below. Above the roll (30), a press roll (21) is used, by means of which the roll (30) is kept stably in its reeling position. The roll (30) is grown around a core (31) under a nip support between the carrier roll (30), a belt roll (12) and the upper press roll (21). When the roll (30) grows and becomes larger, the reeling goes on further under the nip support between the carrier roll (10) and the upper press member (21) and, in addition to this supporting, on a belt supporting zone placed as a direct extension of the nip support zone of the belt roll (12). The final stages of the reeling are carried out up to full roll (30) by extending the belt support zone and, at the same time, by adjusting the tensioning (T) of the support belt or belts (15) so that the linear loads in the various supporting nips of the roll (30) remain within suitable limit values in view of the progress of reeling and of quality of roll (30).

Description: The invention concerns a reeling device for paper web and a method using this reeling device. In respect of the prior art related to the invention, reference is made to the following patent literature: US Patents Nos. 3 098 619, 3 346 209, 4 456 190, 4 485 979, 4 485 980, GB Patent Appl. No. 2 142 909, DE-A-3 121 039, Finnish Patent Nos. 49,276 and Finnish Patent Applications Nos. 843184 and 844652. In the making of paper rolls reeled while supporting the paper rolls by the circumference, a problem consists of internal damage in the large and heavy paper rolls. Damage is produced in particular underneath the surface layer. Some of the commonest damage consists of crêpe wrinkles in the transverse direction of the web and of web cracking. The main cause of the damage has been ascertained to be an excessively high nip pressure between the paper roll and the carrier roll, resulting from the weight of the paper roll or from an excessive press-roll load. In order that a paper roll of good quality could be obtained by means of a carrier-roll reel-up, it has been noticed that the linear load between the paper roll and the carrier roll shall be about 1 to 4 kN/m. Within this range of linear load, it is, as a rule, possible to accomplish the desired distribution of tension in the paper roll. When a carrier roll of a short radius is used, with large paper rolls the above range of linear load is exceeded at the final stage of the reeling, whereby the contact pressure rises to a level higher than that tolerated by a printing-paper roll, which results from the narrow nip area between the paper roll and the carrier roll. In a way known in prior art, attempts have been made to eliminate this problem by making the carrier roll larger, which increases the costs of manufacture and operation of the reel-up. From the Finnish Patent Application No. 843184 a soft-faced carrier roll is known, in which the nip face becomes larger, but a drawback is the dynamic problem of formation of two faces as well as the generation of heat during the reeling. Attempts have also been made to solve said problems by dividing the load on carrier rolls of different sizes or on inclined carrier rolls. Distribution of the load between rolls does not reduce the maximum pressure, but it increases the pressure between one of the carrier rolls and the paper roll, depending on the diameters and on the inclination. The most uniform distribution of the roll pressure is obtained with equally large carrier rolls placed symmetrically underneath the paper roll by using the construction known from the US Patent No. 4 456 190 or DE-A-2 757 247. The last document corresponds to the preamble of independent claims 1 and 6. The main object of the present invention is to provide such a method in a reel-up with support by the circumference by means of which a paper roll as good a possible is obtained, i.e. a paper roll with no reeling defects and with a desired distribution of density as a function of the paper roll diameter. A further object of the present invention is to provide such a reeling method and reeling device by whose means the diameter and the weight of the paper rolls to be made can be increased, if necessary, as compared with paper rolls made by means of prior-art reel-ups with support by the circumference. In view of achieving the objectives given above and those that will come out later, the device and the method according to the invention are disclosed in independent claims 1 and 6. By means of a reel-up in accordance with the invention, it is possible to produce a paper roll of higher quality, which has no defects and whose density is as desired, e.g. invariable. These advantages of the invention are achieved substantially by means of the novel method and belt-supporting device, wherein the support of the paper roll from underneath is regulated by adjusting the tension of the belts. Said adjustment of tension is carried out in such a way that it does not have a disturbing effect on the length of the support zone in the belt-supporting unit or on the distribution of the support pressure. In the following, the invention will be described in detail with reference to some exemplifying embodiments of the invention illustrated in the figures in the accompanying drawing, the invention being by no means strictly confined to the details of said embodiments. Figure 1A is a side view of a reel-up in accordance with the invention at the initial stage of reeling. Figure 1B is a schematical illustration of a reel-up in accordance with the invention and of a control method for same at the final stage of reeling. Figure 2A, 2B and 2C show different stages of the method of the invention with different web roll diameters. Figure 3 illustrates essential quantities related to the geometry and statics of the reel-up and of the support of the web roll. Figure 4 is a graphic and schematical illustration of the distribution of the pressures in the different support nips in the direction of the circumference of the web roll. Figures 1A and 1B are schematical side views of some advantageous exemplifying embodiments of the reel-up of the invention. The reel-ups shown in Figs. 1A and 1B comprise a rear carrier roll 10, which is provided with a mechanical rotating drive 10a. The carrier roll 10 is mounted by its axle journals on bearing supports 11, which are attached to the frame part 40 of the device, which is shown only schematically. The reel-up further comprises a press roll 21, which may be provided with a drive 21a. The press roll is attached to arms 22, which are linked to the frame part 40 of the device permanently at the articulation point 23. The press roll 21 is loaded by cylinders 24, which are, at their articulation points 25, attached to the frame part 40. The piston rods 24a of the cylinders 24 are attached to the arms 22 at the articulation points 24b. Besides by the carrier roll 10, the web roll 30 that is being formed is also supported from underneath by a belt support unit 20, and therein directly by the upper run of the carrier belt 15, which runs between the belt rolls 12 and 13. The first belt roll 12 is provided with a rotating drive 12a. The roll 12 is mounted by its axle journals on supports 14a, which are attached to a first intermediate part 16. The first intermediate part 16 is, by the intermediate of the articulated joint 20a, attached to the part 16a, which is supported on the frame part 40. The supports 14a and the first intermediate part 16 are pivoted around the articulated joints 20a by the hydraulic cylinders 17. The second belt roll 13 is mounted by its axle journals on supports 14b, which are fitted in connection with a second intermediate part 18. The intermediate parts 16 and 18 are interconnected by the arm 19, which is attached to said intermediate parts 16 and 18 by means of horizontal articulated joints 20a and 20b. To the upper ends of the intermediate parts 16 and 18, bearing supports 14a and 14b are attached, on which the belt rolls 12 and 13 are journalled. To the upper parts of the bearing supports 14a and 14b, flange parts 32a and 32b are attached, between which the hydraulic cylinder 26 and its piston rod 26a are arranged by means of link pins 33a and 33b. By means of a pair of hydraulic cylinders 26, the tension T of the belts 15 is adjusted. The intermediate parts 16 and 18, the arms 19 and the hydraulic cylinders 26, form a pair of rhomboids, which is provided with the hydraulic cylinders the articulation points 20a, 20b, 20c and 20d. When the belt 15 is tensioned by extending the cylinders 26, 26a pivoting takes place around the articulation points 20b and 20c, as the articulated joint 20a is immobilized by the cylinders 17. The positions of the belt rolls 12 and 13 are substantially fixed, and the position of the belt roll 13 is altered in the direction of the runs of the belt 15 between the belt rolls 12 and 13, by the effect of the cylinders 26, only to the extent that is necessary in order to adjust the tensioning T of the belt 15 and to replace the belt 15. Figures 1A and 1B are schematical side views, and it is understood that for the support of the various rolls 10, 12, 13, 21 there are corresponding axle journals, supports, arms 22, cylinders 17, 24, 26 and 28, etc. also at the opposite side of the device. The radious R KT of the carrier roll 10 must be chosen in accordance with the width and the running speed of the machine. As a rule, R KT = 500 to 1000 mm, preferably 500 to 850 mm. The bending of the belt 15 and the durability of the bearings determine the radius R HT1 of the belt roll 12. As a rule, R HT1 ≈ 300 to 600 mm, preferably about 400 mm. The radius of the second belt roll 13 may be the same as R HT1 . The radius R PT of the press roll 21 is determined by the radius of the core 31 and by R KT and R HT1 , and R PT ≈ 100 to 500 mm, preferably 200 to 300 mm. The articulation point x, y of the press roll 21 and the length L of its arm are determined so that it is possible to load and to support the web roll 30. The distance D₁ between the carrier roll 10 and the belt roll 12 is determined in accordance with the core 31, with said rolls 10, 12, and with the press roll 21 so that it is possible to load the core 31 ( 90), and D₁ ≈ 10 to 50 mm, preferably about 30 mm. The angle a₁ of the belt roll 12 relative to the carrier roll 10 determines the diameter with which the belt 15 starts supporting the web roll 30. A large positive angle a₁ causes a high nip load at the carrier roll 10 (the weight of the web roll tilts rearwards). A large negative angle a₁ causes a necessity to load too much be means of the press roll 21. The angle a₁ is within the range of -20° < a₁ < 20°. The angle a₂ of the belt roll 13 relative the belt roll 12, together with D₂, determines the maximum diameter 2R o of the web roll 30. If the belt roll 13 is shifted during running, a₂ also affects the direction of the supporting force of the belt 15 during running and, consequently, the form of the tension function. Figs. 1A and 2A show the start of reeling. The core 31, onto which the web roll 30 i reeled, has been brought by means of the core lock 31a into the space between the rolls 10, 12 and 21 so that these rolls form the supporting nips for the core and for the web roll 30 that is about to start its growth. As is shown in Fig. 2B, the diameter 2 x R k of the web roll 30 has grown to about 400 to 700 mm. Thereat the distribution of the nip pressure in the nip 10/30 in the direction S of the circumference of the web roll 30 is P kt2 (Fig. 4), and the nip pressure in the extended nip 30/12, 15 is P ht2 + P h2 (Fig. 4), so that the belt 15 has, on its portion S h2 , started carrying the web roll 30 from below, and the length of this nip in the direction S of the circumference has increased. The length of the nip 10/30 has also increased from the length S k1 on the initial situation to the length S k2 , at the same time as the peak pressure P maxk1 has gone down to the pressure value P maxk2 . As is shown in Fig. 2C, the web roll 30 has grown to its full diameter 2 x R o , whereby the length of the nip 10/30 has increased, in accordance with Fig. 4, owing to the increase in the radius of the web roll 30, to the length S k3 and the peak pressure has gone down to the pressure P maxk3 . At the same time, the length of the supporting zone of the belt unit 12, 15, 13 has increased to its full length S h3 , and the distribution of pressure P h3 is evenly flat. It should be emphasized that Fig. 4 is an illustration of principle concerning the distribution of pressures and does not necessarily show the different distributions, pressure values or the lengths S of supporting nips in compliance with reality. In the following, with reference to the denotations in Fig. 1, the geometry and statics of the reeling in accordance with the invention will be described. In a static examination, the web roll weight G and the vertical component of the linear load F pt of the press roll 21 are carried by the vertical components of the linear load F kt of the carrier-roll nip 10/30, of the linear load F ht of the first belt roll 12, and of the linear load F h caused by the tensioning T (N/m) of the belt 15. The web roll 30 and the second belt roll 13 do not necessarily have a loaded nip. A corresponding static equilibrium prevails in respect of the horizontal components of the linear loads F kt , F ht , F h and F pt . The geometry and statics of the system as well as the linear loads optimal in view of the reeling keep changing all the time as the radius R of the web roll 30 increases. The distribution of density of the web roll 30 as a function of the radius R is determined mainly by the distribution F kt (R) of the linear load of the rear carrier roll 10. This is above all due to the fact that the web W in is introduced onto the web roll 30 exactly via the carrier roll nip 10/30. As a rule, what is aimed at is an invariable density of the web roll 30 as a function of the radius R. Thereat, the linear load F kt in the nip 10/30 must be slowly rising along with the growth of the radius. With different paper qualities, the linear load F kt in the nip 10/30 must be at different levels, and the steepness of the change as a function of the radius R is preferably variable. The linear loads F pt and F ht of the press roll 21, which contacts the web roll 30 directly, and of the first belt roll 12, which contacts the web roll 30 through the belt 15, must be within certain limits, of which the lower limit is determined by the fact that the web roll 30 must be supported adequately and stably during the reeling, and the upper limit by the fact that the rolls 12 and 21 must not sink into the web roll 30 to a disturbing extent. The bearing supports 14a and 14b of the belt rolls 12 and 13 are interconnected by means of a pair of hydraulic cylinders 26, whose direction of movement is parallel to the direction of the run of the belt 15 between the belt rolls 12 and 13. By passing a controlled pressure p t into the cylinders 26, it is possible to adjust the tension T of the belt 15. The pressure load caused by the tension T on the outer circumference of the web roll 30 in the radial direction of the web roll 30 can, in principle, be calculated from the formula p = T/R , so that this pressure load is also affected by the radius R of the web roll 30, in addition to the effects of changes in the geometry of the support. The control of the reeling is governed by the measurement of the radius R of the web roll 30 or of any other, equivalent quantity, because the geometry and the statics of the support and formation of the web roll 30 depend on the radius R or equivalent. According to Fig. 1B, the radius R is measured by means of a revcounter 120 of the carrier roll 10 and by means of a revcounter 130 of the core lock 31a, whose signals r₁ and r₂ are passed to the central unit 100. From the signals r₁ and r₂, the weight G of the web roll 30 can also be derived directly if the grammage of the web W to be reeled has been fed to the system 100. In order to ensure the operation, the radius R of the web roll 30 is also measured by means of measurement of the angle a of the loading arms 22 of the press roll 21, taking place in the unit 110, from which measurement it is possible to calculate the radius R of the web roll 30, the corresponding signal a being passed to the central unit 100. The central unit 100 is either a controllable logic unit or a computer, in which the values of the adjustment quantities p k and p t of the system, as a function of the radius R of the web roll 30 or equivalent, such as weight or the like, have been stored as tables or as functions separately for each of the different quality groups and for the invidivual qualities in the groups as modified, e.g. by means of correction factors. In the following a table is given, wherein the web roll weight, the linear loads F pt , F kt , F ht and F h , the pressure p t , and the belt tension T are given at the values of 100 to 1500 mm of the web roll diameters 2R with steps of 100 mm. The objective of said table is to illustrate a preferred exemplifying embodiment of the invention. The web W to be reeled is a SC or LWC paper of a density of 1200 kg/cm³, and the length of the web roll is 3.6 m. The data given in Table 1 are stored in the memory of the programmable logic unit or computer included in the central unit 100 as a table or as functions. When the species is changed, new tables or functions stored in the memory can be taken into use, or the values of the preceding tables or functions can be modified by means of certain correction factors, which are obtained either from the program or from the unit 100. 2R G F pt F kt F ht F h P k P t T mm kg/3,6 m kN/m kN/m kN/m kN/m bar bar kN/m 100 34 1,20 1,46 1,29 0,00 41,88 95,49 20,00 200 136 1,45 1,55 1,18 0,00 32,37 95,49 20,00 300 305 1,40 1,59 1,35 0,00 32,75 95,49 20,00 400 543 1,45 1,65 1,81 0,00 33,30 95,49 20,00 500 848 1,45 1,70 1,96 0,56 33,82 95,49 20,00 600 1221 1,45 1,77 1,41 2,03 32,27 100,27 21,00 700 1663 1,45 1,85 1,29 3,27 30,65 100,27 21,00 800 2171 1,43 1,89 1,40 4,49 30,38 102,65 21,50 900 2748 1,40 1,90 1,62 5,79 31,27 107,43 22,50 1000 3393 1,40 1,95 1,83 7,30 29,00 114,59 24,00 1100 4105 1,30 2,00 1,85 9,12 28,71 124,14 26,00 1200 4886 1,10 2,03 1,94 10,97 32,88 131,30 27,50 1300 5734 0,65 2,08 1,82 12,99 41,99 137,03 28,70 1400 6650 0,01 2,12 2,20 14,53 52,30 133,69 28,00 1500 7634 0,01 3,34 2,35 16,25 49,80 123,19 25,80 From the above Table 1 as well as from Fig. 4 the following can be noticed. The weight G of the web roll 30 increases naturally in proportion to the second power of the radius R. As can be concluded from the column F kt , the linear load F kt is increased substantially evenly as the radius grows. What is aimed at hereby is an invariable distribution of the density in the web roll 30. The tension T of the carrier belt 15 has a certain upper limit, in consideration of the strength of the belt 15, which upper limit is not permitted by the control system to be exceeded in any situation. The linear load F pt of the press roll 21 dominates the web roll control with smaller radii R, and with larger radii R the linear load F pt of the press roll 21 is lowered, because the weight G of the web roll 30 is increasing. According to the invention, when the tension T of the belt 15 is used as the principal control quantity with larger web roll diameters of 2R > 500 mm, the linear load F kt can be controlled and the linear loads F ht and F pt be kept within the permitted limits, which are determined by the geometry of the reel-up and by the web W to be reeled. A further advantage is that thereat, when a sufficiently long (S h3 , Fig. 4) nip sector between the belt rolls 12 and 13 is used, the surface pressure (P h3max , Fig. 4) caused by the linear load F h between the outer circumference of the web roll 30 and the tensioned belt 15 never becomres higher than permitted, but in respect of this surface pressure it is always possible to operate within an advantageous and safe area. In the following, the patent claims will be given, whereat the various details of the invention may show variation within the scope of the inventive idea defined in said claims and differ from the details described above for the sake of example only.

Claims: Reeling device for paper web including at least two supporting units (10, 20), of which the first one, in the direction of arrival (W in ) of said web, is a carrier roll (10), which is provided with a mechanical rotating drive (10a), over whose sector (b) said web is passed for reeling and which forms a reeling nip (10/30) supporting the web roll (30) from below, and further including a press member unit, preferably a press roll unit (21, 21a, 22, 23, 24, 25), which keeps the web roll (30) stably in its reeling position, characterized in that the second supporting unit in the direction of arrival (W in ) of said web is a belt support unit (20), which supports the web roll (30) from below together with said carrier roll (10), which belt support unit (20) includes belt rolls (12, 13) around which carrier belts (15) or belt are fitted, whose upper run supports the web roll (30) from below at least in the final stages of the reeling with larger roll radii (R), and which belt support unit (20) includes a power unit arrangement (26, 26a, 32a, 33a, 32b, 33b) connected to be effective between said belt rolls (12, 13) substantially in the direction situated in a plane placed through the axes of rotation of said belt rolls (12, 13) to adjust the tensioning of said belt or belts (15). Reeling device as claimed in claim 1, characterized in that the first belt roll (12) of said belt support unit (20) placed next to said carrier roll (10), is a driven roll journalled on a first intermediate part (16), the second belt roll (13) is attached to a second intermediate part (18), which is attached to said first intermediate part (16) by articulated joints (20a, 20b) and arms (19), the first end of said power unit arrangement (26), preferably a pair of hydraulic cylinders, is attached to said first intermediate part (16) or to a first part (14a, 32a) attached to said first intermediate part (16) and the other end of said power unit arrangement (26) is attached to said second intermediate part (18) or to a second part (14b, 32b) attached to said second intermediate part (18). Reeling device as claimed in claim 1 or 2, characterized in that said belt support unit (20) has several belts (15) placed side by side. Reeling device as claimed in claim 2 characterized in that said arms (19) included in the side frames of said belt support unit (20) are attached to the lower part of said first intermediate part (16) pivotably by horizontal joints (20a) and that said arms (19) are supported on the frame (40) or foundation (50) of the machine by support arms (16a, 28), preferably for one (28) of said support arms (16a, 28) by support power units, especially by support hydraulic cylinders, which enable said second belt roll (13) to be displaced. Reeling device as claimed in any of the claims 1 to 4, characterized in that the belt support unit (20) comprises only two belt rolls (12, 13), between which there is said power unit arrangement (26), preferably said pair of hydraulic cylinders, arranged in such a way that adjustment of the tensioning (T) of the belt or belts (15) has no substantial effect on the length of the support zone of said belt support unit (20) or on the form of the distribution of the support pressure. Method for reeling a paper web using the reeling device as claimed in claims 1-5, wherein said web is reeled by supporting the web roll (30) to be formed onto a core (31) or equivalent from its circular cylindrical outer circumference by at least two supporting units (10, 20), of which the first one, in the direction of arrival (W in ) of said web, is a carrier roll (10), which is provided with a mechanical rotating drive (10a), over whose sector (b) said web is passed for reeling and which carrier roll (10) forms a reeeling nip (10/30) supporting the web roll (30) from below, and a press member, preferably a press roll (21), is used above said web roll (30) to keep said web roll (30) stably in its reeling position, characterized by the following steps: (a) said web roll (30) is grown around said core (31) or equivalent under a nip support between said carrier roll (10), a belt roll (12), and said press member, preferably said press roll (21) (Fig. 2A); (b) when said web roll (30) grows and becomes larger than a certain radius (R k ), the reeling goes on further under a nip support between said carrier roll (10), said press member (21) and a belt support unit (20) placed as a direct extension of the nip support of said belt roll (12) (Fig. 2B); (c) the final stages of the reeling are carried out up to full radius (R o ) of said web roll (30) in accordance with the preceding step (b) as said web roll (30) radius (R) is increased and extends said belt support unit (20) and, at the same time, adjusting of the tensioning (T) of the support belt or belts (15) take place, so that the linear loads in the various supporting nips of said web roll (30) remain with suitable limit values in view of the progress of reeling and of quality of said web roll (30). Method as claimed in claim 6, characterized in that in said final stages of the reeling, with those radii of said web roll (30) that are close to the radius (R o ) of complete roll, said web roll (30) is supported by means of said belt support unit (20) in such a way that the outer circumference of the web roll (30) is placed close to said outer belt roll (13) or forms a nip of a low linear load with said belt roll (13). Method as claimed in claim 6 or 7, characterized in that the tensioning (T) of the belt or parallel belts (15) in said belt support unit (20) are adjusted by shifting the opposite belt rolls (12, 13) relative each other by means of a power unit arrangement (26), whose direction of effect is substantially parallel to the main direction of the runs of said belt (15) between said belt rolls (12, 13). Method as claimed in claim 8, characterized in that said belt rolls (12, 13) are shifted for the purpose of adjusting the tensioning (T) of the belt in a plane which forms an angle a₂ with the horizontal plane and said angle a₂ is within the range of 0° to 45°, preferably 5° to 20°. Method as claimed in any of the claims 6 to 9, characterized in that the radius (R) of said web roll (30) being formed is measured by revolution detectors (120, 130) of said carrier roll (10) and of the core lock (31a) and/or by a detector (110) of the position of the support arms (22) of said press roll (21) or of a part attached to said arms (22), and that the signals (r₁, r₂, a) of said detectors (120, 130, 110) are passed to the control system (100), the tensioning (T) of said belt or belts, and preferably also the pressure (p k ) in the relieving cylinders (24) of said press roll (21), being adjusted on the basis of tables and/or functions stored in the memory of said control system (100).

Inventors: RAUDASKOSKI, VESA, SAUKKONEN, SEPPO, TOMMA, KAUKO
Applicants: VALMET PAPER MACHINERY INC.
Application year: 1988
Main classification: B65H18
IPC codes: B65H18