CALENDER AND METHOD FOR CONTROLLING SUCH A CALENDER

Abstract

A calender includes a rotatable roller, and a belt co-acting with the roller with a determined belt pressure. At least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender. The calender also includes means for heating the fluid and/or the roller, control means for controlling the heating means and/or the belt pressure and/or the contact time, and at least one first temperature sensor for measuring the temperature of an outer periphery of the roller and at least one second temperature sensor for measuring the temperature of the fluid. The control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and the measured fluid temperature. A set with a plurality of such calenders and a method for controlling such a calender.

Claims

1. A calender, comprising: a rotatable roller, which roller is hollow and thereby defines an internal space which is configured to be filled at least partially with a heatable fluid; a belt, co-acting with the roller, with a determined belt pressure, wherein at least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender; heating means for heating the fluid and/or the roller, which heating means are disposed in the internal space; one or more control means for controlling the heating means and/or the belt pressure and/or the contact time, at least one first temperature sensor for measuring the temperature of an outer periphery of the roller, and at least one second temperature sensor for measuring the temperature of the fluid, wherein the one or more control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and the measured fluid temperature.

2. The calender according to claim 1, comprising a database in which at least one of the following data is stored, periodically: the measured outer periphery temperature of the roller; a or the measured fluid temperature; the contact time; the belt pressure; a number of revolutions of the roller since the start of a calendering process; at least one property of the at least one material being fed through the calender; at least one property of a transfer paper optionally being fed through the calender; an ambient temperature; an air humidity; which calender is used; a power of drive means of the calender; and at least one property of a belt of the calender, and wherein the control means are further configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in the database.

3. The calender according to claim 2, wherein the control means are configured to determine on the basis of at least periodically measured outer periphery temperatures and periodically measured fluid temperatures of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time must be set in order to obtain a desired outer periphery temperature in the current calendering process, and to control the heating means and/or the belt pressure and/or the contact time in the determined manner.

4. The calender according to claim 2, wherein the database and the control means are connectable to each other wirelessly or via a computer network.

5. The calender according to claim 1, wherein the at least one first temperature sensor comprises a thermocouple arranged against the outer periphery of the roller.

6. The calender according to claim 1, wherein the at least one first temperature sensor comprises an infrared sensor arranged at a distance from the roller.

7. The calender according to claim 1, comprising a plurality of first temperature sensors which are disposed distributedly over the width of the roller for measuring the temperature of an outer periphery of the roller distributed over the width of the roller.

8. The calender according to claim 1, further comprising flow influencing means for initiating and/or influencing a flow of the fluid in the internal space, wherein further control means are configured to control the flow influencing means and thereby the flow of the fluid in the internal space in freely settable manner.

9. A method for controlling a calender according to claim 1, which method comprises the following steps of: a) measuring the outer periphery temperature of the roller; b) controlling the heating means and/or the belt pressure and/or the contact time by means of the one or more control means on the basis of the outer periphery temperature measured in step a); and c) measuring the fluid temperature, wherein in step b) the control means also control the heating means and/or the belt pressure and/or the contact time on the basis of the fluid temperature measured in step c).

10. The method according to claim 9, further comprising, before step b) the step of: setting or determining a target temperature for the outer periphery of the roller; wherein in step b) the one or more control means control the heating means and/or the belt pressure and/or the contact time for the purpose of heating the outer periphery of the roller and/or keeping the roller at the target temperature up to at least roughly the desired target temperature.

11. The method according to claim 9, comprising controlling a calender, the calender comprising: a rotatable roller, which roller is hollow and thereby defines an internal space which is configured to be filled at least partially with a heatable fluid; a belt, co-acting with the roller, with a determined belt pressure, wherein at least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender; heating means for heating the fluid and/or the roller, which heating means are disposed in the internal space; one or more control means for controlling the heating means and/or the belt pressure and/or the contact time, at least one first temperature sensor for measuring the temperature of an outer periphery of the roller, and at least one second temperature sensor for measuring the temperature of the fluid, wherein the one or more control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and the measured fluid temperature; a database in which at least one of the following data is stored periodically: the measured outer periphery temperature of the roller; a or the measured fluid temperature; the contact time; the belt pressure; a power of the heating means; a number of revolutions of the roller since the start of a calendering process; at least one property of the at least one material being fed through the calender; at least one property of a transfer paper optionally being fed through the calender; an ambient temperature; an air humidity; which calender is used; a power of drive means of the calender; and at least one property of a belt of the calender, and wherein the control means are further configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in the database wherein in step b) the control means is configured to control the heating means and/or the belt pressure and/or the contact time on the basis of at least one of the data stored in the database.

12. The method according to claim 11, comprising controlling a calender, the calender comprising a rotatable roller, which roller is hollow and thereby defines an internal space which is configured to be filled at least partially with a heatable fluid; a belt, co-acting with the roller, with a determined belt pressure, wherein at least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender; heating means for heating the fluid and/or the roller, which heating means are disposed in the internal space; one or more control means for controlling the heating means and/or the belt pressure and/or the contact time, at least one first temperature sensor for measuring the temperature of an outer periphery of the roller, and at least one second temperature sensor for measuring the temperature of the fluid, wherein the one or more control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and the measured fluid temperature; a database in which at least one of the following data is stored periodically: the measured outer periphery temperature of the roller; a or the measured fluid temperature; the contact time; the belt pressure; a power of the heating means; a number of revolutions of the roller since the start of a calendering process; at least one property of the at least one material being fed through the calender; at least one property of a transfer paper optionally being fed through the calender; an ambient temperature; an air humidity; which calender is used; a power of drive means of the calender; and at least one property of a belt of the calender, wherein the control means are configured to determine on the basis of at least periodically measured outer periphery temperatures and periodically measured fluid temperatures of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time must be set in order to obtain a desired outer periphery temperature in the current calendering process, and to control the heating means and/or the belt pressure and/or the contact time in the determined manner; which method further comprising the step e) of determining by means of the control means and on the basis of at least periodically measured outer periphery temperatures and periodically measured fluid temperatures of a plurality of prior calendering processes and on the basis of at least the at least one property of the same material how the heating means and/or the belt pressure and/or the contact time must be set in order to obtain a desired outer periphery temperature in the current calendering process, and of controlling the heating means and/or the belt pressure and/or the contact time in the determined manner.

13. The method according to claim 9, comprising controlling a calender, the calender comprising: a rotatable roller, which roller is hollow and thereby defines an internal space which is configured to be filled at least partially with a heatable fluid; a belt, co-acting with the roller, with a determined belt pressure, wherein at least one material for feeding through the calender is situated between the roller and the belt for a determined contact time during throughfeed through the calender; heating means for heating the fluid and/or the roller, which heating means are disposed in the internal space; one or more control means for controlling the heating means and/or the belt pressure and/or the contact time, at least one first temperature sensor for measuring the temperature of an outer periphery of the roller, at least one second temperature sensor for measuring the temperature of the fluid, wherein the one or more control means are configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and the measured fluid temperature; and flow influencing means for initiating and/or influencing a flow of the fluid in the internal space, wherein further control means are configured to control the flow influencing means and thereby the flow of the fluid in the internal space in freely settable manner; which method further comprises the following steps of: f) setting or determining a setting of the flow influencing means; g) controlling the flow influencing means, and thereby the flow of the fluid in the internal space, by means of the control means so as to achieve the setting set or determined in step f).

14. The method according to claim 10, wherein at least steps a) and b) are performed iteratively.

15. A set with a plurality of calenders according to claim 1, wherein the control means of at least one of the calenders are configured to control the heating means and/or the belt pressure and/or the contact time of that one calender on the basis of periodically registered data of calendering processes performed with the calenders of the set.

Description

[0154] The invention will be further elucidated with reference to the accompanying figures, in which:

[0155] FIGS. 1A and 1B show schematically a calender according to a first embodiment of the invention, wherein FIG. 1A shows a vertical longitudinal section along the width of the calender and FIG. 1B shows a cross-section of the calender;

[0156] FIGS. 2A and 2B show schematically a calender according to a second embodiment of the invention, wherein FIG. 2A shows a vertical longitudinal section along the width of the calender and FIG. 2B shows a cross-section of the calender;

[0157] FIG. 3 show schematically the steps of a method according to a first embodiment of the invention.

[0158] The same elements are designated in the figures with the same reference numerals, increased by 100 for the second embodiment.

[0159] FIGS. 1A and 1B show a calender 1 according to a first embodiment of the invention. Calender 1 can be used for calendering processes, such as for instance transfer and/or fixation processes or laminating processes. Calender 1 comprises a rotatable roller 2, which roller is hollow and thereby defines an internal space 3 which in this case is filled with oil. Internal space 3 connects via a conduit 5 to an expansion tank 4 for the oil. Calender 1 comprises a drive shaft 6 for rotating driving of roller 2. Calender 1 further comprises a belt 7 co-acting with roller 2, which belt 7 is disposed via guide rollers 8 round a part of the periphery of roller 2, see FIG. 1B. For the sake of simplicity belt 7 is not shown in FIG. 1A. As is visible in FIG. 1B, a material 9 can be fed through between roller 2 and belt 7 for a determined contact time during a calendering process, wherein the contact time can particularly be the amount of time during which the material 9 is in direct or indirect contact with roller 2. The contact time can for instance depend on a rotation speed of roller 2. Disposed in this case in the internal space 3 of roller 2 are a plurality of heating elements 10, which heat the oil. Because the oil is heated, the oil can heat roller 2. A calendering process can particularly be controlled on the basis of at least one of the following three parameters, i.e. the degree of heating, which can for instance be set by setting a power of heating elements 10, a belt pressure, which can for instance be set by tightening belt 7 or arranging it more loosely, for instance using guide rollers 8, and the contact time, which can for instance be set by selecting a suitable rotation speed, i.e. number of revolutions, of roller 2. Calender 1 comprises for this purpose one or more control means, for instance in the form of a processor (not shown).

[0160] Several aspects of the invention will be elaborated further hereinbelow. The aspects can be provided alone or in combination. The elements of calender 1 further described in the context of the aspects can each be provided alone or in combination.

[0161] According to an aspect of the invention, calender 1 comprises in this first exemplary embodiment flow influencing means for initiating and/or influencing a flow of the oil in internal space 3. In this case the flow influencing means comprise a rotor 20 which is disposed in roller 2 and is rotatably drivable by a drive shaft 21. In this example rotor 20 comprises a plurality of blades 22, using which the oil can be set into motion. In this example rotor 20 comprises a cylindrical body, wherein the blades 22 extend outward from the cylindrical body, substantially in the direction of roller 2. The oil is situated between rotor 20 and roller 2. The drive shaft 6 for rotating driving of roller 2 and the drive shaft 21 for rotating driving of rotor 20 are configured to drive roller 2 and rotor 20 separately of each other. Rotor 20 can particularly be driven in a rotation direction 23, which rotation direction 23 is opposite to a rotation direction 24 of roller 2, see FIG. 1B. The flow direction of the oil can hereby be set to a direction opposite to roller 2. The rotation speed of rotor 20 can be set between 0 revolutions/s, i.e. the rotor does not rotate, and a maximum rotation speed V.sub.rotor, max, for instance expressed in revolutions/s or revolutions/min. A flow speed of the oil can hereby be set, particularly between a substantially stationary flow and a maximum flow speed V.sub.max. By selecting a suitable rotation speed for rotor 20 the flow of the oil can be laminar, i.e. for 0≤V.sub.rotor≤V.sub.rotor, laminar, or turbulent, i.e. for V.sub.rotor, laminar<V.sub.rotor≤V.sub.rotor, max. By selecting a suitable speed of the oil and/or the flow regime of the oil a heat transfer from the oil to roller 2 can be set, and particularly reduced or increased. The rotor can be controlled by the stated or further control means.

[0162] According to another aspect of the invention, in this first exemplary embodiment calender 1 comprises at least one temperature sensor 30 for measuring the temperature of an outer periphery of roller 2. Temperature sensor 30 is disposed in an area of roller 2 where the material 9 will come into contact with the roller, but at a position where material 9 is guided away from roller 2, see FIG. 1B. Temperature sensor 30 hereby measures the outer periphery temperature at a location relevant to the process, but without influencing the calendering process. FIGS. 1A and 1B show one first temperature sensor 30 but, if desired, a plurality of first temperature sensors 30 can be provided, these being disposed distributed over the width b of roller 2 for the purpose of measuring the temperature of an outer periphery of roller 2 distributed over the width b of roller 2. First temperature sensor 30 is shown schematically in FIGS. 1A and 1B as being arranged on the outer periphery of roller 2. Such a sensor 30 can for instance comprise a thermocouple. Alternatively, it is also possible to dispose the sensor at a distance from roller 2, for instance by using an infrared sensor. In this first embodiment of calender 1 the calender further comprises a second temperature sensor 31 for measuring the temperature of the oil. If desired, a plurality of second temperature sensors 31 can be provided, these being disposed distributed over the width b roller 2 for the purpose of measuring the oil temperature distributed over the width b of roller 2. Such a sensor 31 can for instance comprise a thermocouple. Said control means can be configured to control the heating means and/or the belt pressure and/or the contact time on the basis of the measured outer periphery temperature and optionally the measured oil temperature.

[0163] According to another aspect of the invention, calender 1 or a system of which the calender forms part comprises a database 40 which is wirelessly connected to calender 1 in this example. Data can be stored in database 40, wherein said control means can further be configured to control the rotor 20 and/or the heating elements 10 and/or the belt pressure and/or the contact time on the basis of at least one of the data contained in database 40. At least one of the following data can for instance, though not exclusively, be stored, optionally periodically, in database 40: [0164] the measured outer periphery temperature of roller 2; [0165] the measured fluid temperature; [0166] the contact time; [0167] the belt pressure; [0168] a power of heating elements 10; [0169] number of revolutions of roller 2 since the start of a calendering process; [0170] at least one property of the at least one material 9 being fed through calender 1; [0171] at least one property of a transfer paper optionally being fed through the calender; [0172] an ambient temperature; [0173] an air humidity; [0174] which calender is used; [0175] a power of drive means of the calender; [0176] at least one property of the belt 7 of the calender.

[0177] If desired, database 40 can also store data of other calenders 1. In this way the calender can be controlled even more accurately.

[0178] FIGS. 2A and 2B show a calender 101 according to a second embodiment of the invention. Only the differences with the calender 1 according to the first embodiment of FIGS. 1A and 1B will be described here. For a further description of calender 101 reference is made to the figure description associated with FIGS. 1A and 1B.

[0179] Calender 101 comprises a rotatable roller 102, which roller is hollow and thereby defines an internal space 103, which in this case is filled with air. In this embodiment roller 102 forms a closed system for the air. Disposed in this case in the internal space 103 of roller 102 are a plurality of heating elements 110 which both heat the air and also directly heat roller 102 by means of radiation.

[0180] In this second embodiment the flow influencing means for influencing the flow of, in this case, the air comprise two air conduits 125 with a number of openings 128 via which air can flow into the internal space 103 of roller 102. Openings 128 are formed and/or provided with orienting means such that the air flows into space 103 in a direction 123 which is opposite to the rotation direction 124 of roller 102. Air conduits 125 extend through roller 102 and are connected via an outer side of roller 102 to, in this case, two air discharge conduits 126. Air discharge conduits 126 comprise openings 129 for drawing in air. The air extracted via the air discharge conduits 126 can be supplied to roller 102 again via air conduits 125. A pump 127 is provided for the purpose of extracting and blowing in the air. Pump 127 can be set between a minimum power of 0, wherein no extraction and blowing in of the air takes place and wherein the air is substantially still, and a maximum power V.sub.pump, max whereby a maximum flow speed of the air is brought about. By selecting a suitable power for pump 127 the flow of the air can be laminar, i.e. for 0≤V.sub.pump≤V.sub.pump, laminar, or turbulent, i.e. for V.sub.pump, laminar<V.sub.pump≤V.sub.pump, max By selecting a suitable speed of the air and/or the flow regime of the air a heat transfer from the air to roller 102 can be set, and particularly reduced or increased. The pump 127 can be controlled by the stated or further control means.

[0181] Said temperature sensors 130 and/or 131 can if desired also be provided in this second embodiment.

[0182] Said database 140 can if desired also be provided in this second embodiment.

[0183] FIG. 3 shows the steps of a first embodiment of the method according to the invention.

[0184] Step 50 comprises of setting or determining a setting of the flow influencing means. Step 51 comprises of measuring the outer periphery temperature of the roller. Step 52 comprises of measuring the fluid temperature. Step 53 comprises of setting or determining a target temperature for the outer periphery of the roller. Step 54 comprises of making data from a stated or other database available. Step 55 comprises of controlling the flow influencing means and/or the heating means and/or the belt pressure and/or the contact time for the purpose of controlling a calendering process on the basis of at least one of the settings of the flow influencing means set or determined in step 50, outer periphery temperature measured in step 51, fluid temperature measured in step 52, target temperature set or determined in step 53, and data from the database made available in step 54.

[0185] Although the invention is elucidated above on the basis of a number of specific examples and embodiments, the invention is not limited thereto. The invention instead also covers the subject matter defined by the following claims.