FI111018B - Method and apparatus for measuring and controlling the relief pressure of intermediate rollers in a calender - Google Patents

Description

♦ 111018

Method and Device for Measuring and Adjusting the Relaxation Pressure of Intermediate Rollers in a Multi-Roll Calender 5 Förfarande och anordning for mätning och regiering av mellanvalsar vid en kalander 5

The invention relates to a method for measuring and adjusting the relief pressures of intermediate rolls in a multi-roll calender comprising a calender body and a roll stack formed by a roll compensated upper roll, a deflection compensated lower roll, and intermediate rolls the intermediate rollers are mounted on the calender body by means of an oscillation of the articulated loading arms and are provided with pressure medium-operated relief cylinders to partially or completely lighten the masses of the intermediate rolls and associated auxiliaries.

15

The invention also relates to a device for measuring and adjusting the relief pressures of intermediate rolls in a multi-roll calender comprising a calender body and a roll stack formed by a roll compensated upper roll, a deflection compensated lower roll and intermediate rolls mounted on the calender body by means of articulated loading arms and fitted with pressure medium-acting relief cylinders for partially or completely relieving the masses of intermediate rolls and associated auxiliaries.

As usual, the roller of a multi-roll calender comprises a plurality of rolls which are arranged as a roll stack. The rolls are in nip contact with one another and the calenderable paper or board web or similar material web is imaged to pass through the nip rolls. The rollers are rotatably mounted on bearing housings which, in modern multi-roll calendars, are mounted on load arms that are pivotally pivoted on the calender body. In addition, the loading arms are generally provided with relief cylinders for applying to the loading arms a relief force to relieve part or all of the loads caused by the weight of the rollers and auxiliaries attached to the loading arms. For example, such calendars statistics and lightening devices are referred to, for example, in Finnish patent applications Nos. 935214,961912 and 982686.

5

In a multi-roll calender, where the intermediate rolls are mounted on the calender body by loading arms or similar levers as described above, the geometry of the levers changes with respect to the loads, according to the position of the roller, i.e. as the roller is closed. Since the geometry of the calender roll relief system is quite 10 different in the roll start situation, i.e., when the roll resting on its movement limiters is barely displaced by the action of the relief cylinders, compared to the , has nothing to do with the pressure-15 pressure of the roll relief rollers. Due to the geometry of the loading system, the need for lifting force generally decreases as the roller rises, requiring more pressure to lift the roller than to hold it in the relief position with the nipples closed. In current multi-roll calendars, the relieving pressure and accuracy of the intermediate roll lightening devices cannot be reliably determined. In particular, the lifting and lightening pressures of the roll cannot and must not be averaged.

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It is an object of the present invention to provide a novel method and apparatus for measuring and adjusting the relief pressures of intermediate rolls in a multi-roll calender. To achieve this object, the method according to the invention is essentially characterized in that the riveting intermediate roll is driven to the overhead roll and the force exerted on the overhead roll to measure the roll is measured.

The device according to the invention is essentially characterized in that the device is a measuring device with a force sensor 30, which is removably attached to the supporting structures of a measurable intermediate roll, such as a bearing housing or a loading rod, to measure the forces exerted by the roller above it.

The solution according to the invention provides a significant advantage over the prior art, since the invention enables very accurate measurement of the relief pressures. The measurement according to the invention can be carried out very simply using a simple device mounted on the calender during the measurement. Execution of the method and use of the device do not require any substantial changes to the structure of the calender itself, but the method and device of the invention are as such applicable to existing calendars. Other advantages and features of the invention will become apparent from the following detailed description of the invention.

The invention will now be described, by way of example, with reference to the figures in the accompanying drawing.

Figure 1 is a full schematic side elevational view of a multi-roll calender to which the method and apparatus of the invention is applicable.

Figure 2 shows a measuring device mounted in the calender of Figure 1.

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Figure 1 thus shows a schematic side view of a multi-roll calender in which the method and apparatus of the invention have been applied. The multi-roll calender is generally designated 10 in FIG. 1 and comprises a calender body 11 having a roll stack 12 mounted on a plurality of rolls 25 in a vertical plane. The roll stack 12 includes a top roll 13, a bottom roll 14 and a plurality of intermediate rolls 15-18, which are all tracked so that they are in nip contact with one another when running. In Figure 1, the calender roller 12 is shown in the open position, i.e. the nipples Ni to N5 open. Figure 1 shows an embodiment of the embodiment 30 having four intermediate rolls 15,16,17,18 between the upper and lower rolls 13,14, but the number of intermediate rolls may differ from that shown in the figure.

4, 111018

Preferably, the calender top roll 13 is a deflection compensated zone adjustable roll and its bearing housings 131 are mounted on a mounting frame 132 secured to the calender body 11. The lower roll 14 is similarly preferably a deflection compensated 5 a vertical slider 11a is provided on the slide 143 and on the calender body 11, on which the slide 143 is movably mounted in the direction of the slide 11a. Below the lower roll mounting frame 142 is mounted a lower cylinder 144, i.e. a lifting cylinder, by means of which the mounting frame 142 and the lower roll 14 14 mounted on it can be moved in the direction of the slider 1a. Each spacer roller 15, 16, 17,18 is mounted via its bearing housings (not shown) on the load arms 151, 161, 171, 181 pivotally pivoted on the calender body 11 by the axial axes of the intermediate rollers 152, 162, 172, 182. In the embodiment shown in FIG. each load arm 151, 161, 171, 181 comprises a double-lever with respect to its pivot axis 152, 162, 172, 182 15, provided with relief cylinders 153, 163, 173, 183, which are tracked relative to the intermediate roll 15,16,17,183. , 162, 172,182 to the opposite end of the load arm 151,161,171,181. The Keven nozzle cylinders are pressure medium driven piston-cylinder devices which are secured at one end to said load arms 151, 161, 171, 181 and opposite to the calender body 11. The pressurized medium may be a hydraulic fluid or a compressed air, most preferably a hydraulic fluid. The calender body 11 also has a motion limiter 154, 164, 174, 184 mounted on each load arm 151, 161, 171, 181, on which the load arms rest when the nipples N 1 - N s are opened, i.e. in the situation shown in Figure 1.

25

The geometry of the loading arms 151, 161, 171, 181 of the calender 10 in relation to the loads I l •. changes quite substantially as the track 12 is driven. The lifting pressure of the roll, i.e. the pressure in the relief cylinders 153 of the first intermediate roll 15, by which the roll 15 resting on its motion limiter 154 is displaced, has nothing to do with the relief pressure of the roll 15. This is due to the fact that the geometry of the roller 15 lightening system is quite different in the roll starting 5111018 from the situation where the nipples are closed. Due to the geometry of the loading system, the lifting power requirement decreases as the roller 15 rises, requiring more pressure to lift the roller than to hold it in the relief state with the nipples closed.

5

Since it is important to know the actual lifting and lowering pressures of the rolls for adjusting the rollers, it is simplest to determine them by directly measuring the pressures on the rollers 153, 163, 173, 183. The pressures are measured in a situation corresponding to the roll lifting condition and 100% relief. The pressures measured in this way still have an error due to friction, but not a geometric error. Whenever possible, back pressure must be applied to the relief cylinders during the measurements. Prior to the pressure measurements, the backpressures are adjusted so that the ends of the roll to be measured move simultaneously, i.e. the set backpressures correctly compensate for the effect of the asymmetric masses. Furthermore, during the measurements, the rolls should be crawling to prevent damage to the roll coatings.

The lifting pressures of the rolls can be measured as follows. At the start, all nipples Ni-Ns of the calender 10 are open and the intermediate rolls 15-18 are resting with their motion limiter 154, 164, 174, 184, which corresponds to the situation shown in Figure 1. The pressure in the relief cylinders 153 of the upper 20 intermediate roller 15 is slowly increased either steplessly or in small increments, preferably in steps of up to 0.5 bar. The pressure is measured and recorded as the roller 15 just moves upwards. Thereafter, the relief pressure is increased, i.e. the roller 15 is overheated so much that the top nipple Ni is practically closed. The same procedure is repeated with roll 25 at a time from top to bottom until all but the nip are closed. The lowest nipple Ns is always open and the lower roll 14 does not lift the intermediate rolls.

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The roller relief pressures can be determined as follows. In the lightening pressure determination, the starting position corresponds to the final position of the roller lifting pressure determination, i.e. at 30 initial positions all nips are closed except for the lowest nip N5. Also, when defining the relief pressures, the intermediate rolls 14 must not be lifted by the lower roller 14. When performing the specification, the rack 12 should be practically closed, but nipples Ni to N4 need not be loaded. Most preferably, the rolls are slightly overweight. The pressure in the relief cylinders is then gradually reduced, either stepwise or in small increments, preferably in increments of up to 0.5 bar. The pressure reduction is performed position-by-position starting with the relief cylinders 183 of the lowest intermediate roll 18. The pressure is determined when the roll to be measured just moves downward. The pressure on the relief cylinders 183 is further reduced such that the roll 18 eventually stops on its motion limiter 184.

However, in the measurement performed as described above, the actual reduction pressures cannot be accurately measured, but the measured values can be regarded as indicative only. As a result, special force sensing devices are used to accurately measure the relief pressures. This is further illustrated by Figure 2. For the measurement, the measuring devices are mounted on the bearing housing or the load arm of the roll 15 to be measured. Figure 1 illustrates a situation in which the measuring device 20 is fixed to the load arm 161 of the second intermediate roll 16 or to the bearing housing, respectively.

Referring to Fig. 2, the measuring device 20, more closely, comprises a force transducer 21 attached to a first mounting plate 23 by means of a height adjusting member 22. The measuring device 20 further comprises a second mounting plate 24 secured to a loading arm 161 or a bearing housing. The first fastening plate · 23 and the second fastening plate 24 are connected to one another by means of a joint 25 such that the angle between these fastening plates 23, 24 can be adjusted relative to each other. Thus, for the angle adjustment, the measuring device is further provided with an angle adjusting member 26, 25 which is most simply an adjusting screw shown in Fig. 2, for adjusting the angle between the fastening plates 23,24.

The gauge attached to the roller bearing housing or load arm measures the force exerted from above by the force sensor 21 so that the force sensor 21 corresponds to the load arm or bearing housing of the roller on the upper side. In the situation of Figure 1, the gauge 20 is mounted on the load arm 161 of the second spacer roll 16 or the bearing housing 7111018, respectively, whereby the force transducer 21 of the gauge measures its force from the load arm 151 of the first spacer roll 15. The height adjusting portion 22 of the measuring device 20 is needed because different rolls of different diameters can be used in the same calendar, whereby, due to diameter differences, the distances between the rolls 5 may also differ. Due to the variable angle of the loading arms, an angle adjustment is also required on the measuring device 20. As stated above, the measurement is made by measuring the force exerted above the roll, whereby the measuring device 20 can determine when the weight of the roll is 100% lighter. The measurement is extremely accurate and reliable as the forces are always in the same 10-direction with the production situation.

The invention has been described above by way of example with reference to the figures in the accompanying drawings. However, the invention is not limited to the example shown in the figures, but different embodiments of the invention may vary within the scope of the inventive timing as defined in the appended claims.

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B

Claims (6)

8 111018 A method for measuring and adjusting the relief pressures of intermediate rolls in a plurality of calender comprising a calender body (11) and a roll stack (12) formed of a roll stack comprising a deflection compensated upper roll (13), deflection compensated lower roll (14) and intermediate rolls 15 -18) forming calendering nipples (Ni-N5) with each other when the calender (10) is in an operative position, the intermediate rolls (15 -18) being mounted on the calender body (11) via pivotable loading arms (151,161,171,181) 10 roller cylinders (153, 163, 173,183) for partially or completely lightening the masses of intermediate rolls (15-18) and associated auxiliary devices, characterized in that the intermediate roller (16) to be measured is driven against the roller (15) above and the force exerted by the roll (15) on the measured roll (16). 15 A method for measuring and adjusting the relief pressures of intermediate rolls in a multiple calender comprising a calender body (11) and a roll stack (12) formed of a roll stack comprising a deflection compensated upper roll (13), deflection compensated lower roll (14) and intermediate rolls 15 -18) which, when the calender (10) is in the operating position, form calendering mips (N 1 - N 5) with one another, wherein the intermediate rolls (15 -18) are mounted on the calender body (11) via pivotable loading arms (151,161, 171,181) pressurized fuel-driven roller cylinders (153, 163, 173, 183) to partially or completely lighten the masses of the intermediate rolls (15-18) and associated auxiliary devices, characterized in that the measured intermediate roller (16) is driven onto the overhead roller (15) and in order to determine the relief, the force exerted from the roller (15) above is measured on the roller (16) to be measured. 15 Method according to Claim 1, characterized in that a measuring device (20) with a force transducer (121) is applied to the support structures of the measurable intermediate roll (16), such as the bearing housing or the loading arm (161). 20 Method according to Claim 1, characterized in that a measuring device (20) with a force transducer (121) is applied to the support structures of the measurable intermediate roll (16), such as a bearing housing or a load arm (161). 20 An apparatus for measuring and adjusting the relief pressures of intermediate rolls in a multi-roll calender comprising the calender body (11) and a roll stack (12) comprising a deflection compensated upper roll (13), a deflection compensated lower roll (14) and a top and intermediate rollers (15-18) disposed between the lower rollers which, when the calender (10) is in the operating position, form calendering nipples (Ni-N5) with one another, wherein the intermediate rollers (15-18) are mounted on the loading arms (151,161,171,181) and equipped with pressure-mass-driven lightening cylinders (153, 163, 173, 183) for partially or completely lightening the masses of intermediate rollers (15 -18) and associated auxiliary devices, characterized in that the device is a measuring device (20) with a force sensor (21) attachable measuring roller i - 8 111018 An apparatus for measuring and adjusting the relief pressures of intermediate rolls in a multi-roll calender comprising the calender body (11) and a roll stack (12) comprising a deflection compensated upper roll (13), a deflection compensated lower roll (14) and a top and intermediate rollers (15-18) disposed between the lower rollers which, when the calender (10) is in the operating position, form calendering nipples (Ni-Ns) with one another, wherein the intermediate rollers (15 4-18) are mounted on the loading arms (151,161,171,181) ) and equipped with pressure medium driven mixing cylinders (153, «163,173, 183) for partially or completely reducing the masses of intermediate rolls (15-18) and associated auxiliary devices, characterized in that the device is a measuring device (20) equipped with a force transducer (21). , which is removably attachable to a metering roller 10 111018