Calender for generating maximum line forces, method for operating a calender

Abstract

A calender (100) for calendering planar structures, preferably for the production of electrodes, is proposed, comprising a first roller (1) and a second roller (2), wherein the rollers (1, 2) can be displaced relative to each other along a first axial direction (A1) of the first roller (1) and / or along a second axial direction (A2) of the second roller (2), wherein the first roller (1) has a first profile (P1) and the second roller (2) has a second profile (P2), wherein the calender (100) has an interlocking means (7) for interlocking the first roller (1) and the second roller (2) about an interlocking axis (V), wherein the interlocking axis (V) is perpendicular to the first axial direction (A1) and the second axial direction (A2). Furthermore, a method for operating a calender (100) is proposed.

Description

The invention relates to a calender for calendering sheets, preferably for producing electrodes, having a first roll and a second roll. The invention further relates to a method for operating a calender.For calendering sheets, the sheets are typically fed along a fabric direction to a nip between two working rolls of a calender. The sheet passes through the nip and is pressure treated by the rolls of the calender.Modern applications of calenders require the highest precision in the operation of the calender. In particular, precise dimensioning of the roll gap is of the highest importance. Particular attention is paid here to the defined setting, in particular the constancy, of the height of the roll nip along its entire width, that is to say transversely with respect to the direction of the goods. The fact that the actual course of the height of the roll gap corresponds to the desired course of the height of the roll gap is counteracted during operation by difficulties which occur regularly and in principle. The bending of the rollers during calendering of a sheet material is problematic, for example. The bending is typically due to a deformation of the rollers when force is applied to the sheet material. During calendering, the rolls deform due to the line forces in the roll nip. However, especially when high accuracy levels are required, other effects also fall into the focus of interest. Thus, the rolls expand with increasing temperatures. Especially in the case of heated rolls, a completely homogeneous temperature distribution is not possible. Typically, in the case of heated rollers, the temperature falls at the edges, for example because of cooled bearings or because of a larger surface area, via which heat can be dissipated. The inhomogeneous temperature distribution of heated rolls leads to inhomogeneous thermal expansion and thus likewise carries undesired deviations in the gap height.From the prior art, possibilities are known for dealing with the bending of the rollers and for avoiding or compensating this. One possibility is the use of die-supported rollers, in which a device is provided in the interior of the rollers, which compensates bending of the roller shell by the introduction of mechanical forces counter to the bending.This technique becomes problematic in applications in which extremely high accuracy is required under the application of very high line forces. Thus, for example, the thin roll shells of punch-supported rolls cannot be manufactured with any desired precision. Furthermore, die-supported rollers are power-limited as regards the greatest of the line forces to be introduced. Finally, it is difficult to heat up die-supported rolls very homogeneously.A constantly growing field of tasks for calenders is the production of electrodes for battery production. In this case, current-conducting films are coated and subsequently calendered. Calendering determines the density of the electrodes, porosity, adhesion strength and with these parameters also the conductivity and finally the electrochemical performance of the electrodes. Precisions of a gap height of 1 μm with respect to the roller gap along the entire width of the roller gap are required at line forces of more than 500 N / mm up to 10,000 N / mm.In the prior art calenders are used for producing electrodes whose web width typically does not exceed 800 mm. With larger web widths, bending of the rolls occurs, which cannot be compensated for satisfactorily with conventional means. Thus, the application of a bombage to the rollers is inflexible, in particular with changing line forces. Nevertheless, larger web widths are desirable because they significantly improve the efficiency of the production of the electrodes.It is therefore an object of the present invention to provide a calender and a method for operating a calender which do not have the disadvantages of the prior art described, but rather offer the possibility of very uniform adjustment of the nip at high line forces and large web widths.This object is achieved by the features of claim 1 and of claim 8.The calender according to the invention for calendering sheets has a first roll and a second roll. Preferably, the calender is provided for calendering electrodes. The first roll and the second roll are working rolls of the calender. It is conceivable, for example, for the first roll to be an upper roll and the second roll to be a lower roll of the calender. However, it is also conceivable for the second roll to be an upper roll and the first roll to be a lower roll of the calender. Furthermore, it is possible for the first roller and the second roller to be arranged next to one another and for the sheet material to be guided from above, from below or obliquely between the first roller and the second roller. It is also conceivable for the first roller and the second roller to be inclined, that is to say for the axial directions of the rollers not to be aligned horizontally. Finally, it is conceivable that the rolls of the calender are oriented such that the nip plane in the case of non-interleaved rolls, i.e. in the case of parallel-oriented axial directions of the rolls, is inclined, i.e. in particular not vertical. The nip plane is here the plane in which the axial directions of both rollers lie in the non-interleaved state, i.e. at an interleaved angle of zero. The present invention is not limited to a calender which has only two rolls. In addition to the first roll and the second roll, the calender according to the invention can have further rolls.According to the invention, it is provided that the first roller can be displaced along a first axial direction of the first roller and / or that the second roller can be displaced along a second axial direction of the second roller. The axial directions correspond here to the respective roller axes, that is to say the axes about which the roller rotates during operation. Thus, the rollers can be displaced relative to each other.In addition, the calender according to the invention has an entanglement means for entanglement of the first roll and the second roll. In this case, at least one of the rollers is rotated about an entanglement axis which is perpendicular to the first axial direction and perpendicular to the second axial direction. The entanglement axis may be arranged centrally of the first roll and / or the second roll, but need not be.The entanglement of the rolls makes it possible to adjust the nip height at the center of the nip as well as at the outer ends of the nip. If, for example, the roll gap is smaller at the ends than in the middle, then it is possible to interlace about a centrally arranged interlace axis. This causes the rolls to move apart at the ends while the distance remains the same in the middle. If the roll gap is smaller at a first outer end than at a second outer end, then the roll gap can be interlaced about an interlace axis which is arranged at the second outer end. The rollers thus move further apart at the first outer end. The effect of the entanglement always leaves a location of the nip unchanged, namely the location through which the entanglement axis passes, and corrects the remaining areas either towards a larger nip (increase of the entanglement angle between the first axial direction and the second axial direction) or towards a smaller nip (decrease of the entanglement angle). The interleaving ensures good and simple compensation of the deflection in a first approximation. A better-resolution compensation of the deflection, i.e. a compensation which can be set much more freely with respect to the location of the compensation, cannot be achieved by the interleaving.In particular, the combination of interleaving and displacement along the axial directions also makes it possible to compensate in a targeted manner for undesired deviations in the gap height caused by inhomogeneous roller temperatures.In order to be able to achieve this better resolution of the compensation of undesired deviations of the gap height, the rollers are displaced relative to one another along the axial directions. By displacing the rollers, the course of the gap height changes. The combination of displacing the rollers along the axial directions and thus adjusting the course of the gap height via the displacement of the profiles relative to one another and the interleaving of the rollers can set the gap height with high precision and reliably even with very high line forces even in the case of very large web widths, such as 1,500 mm or more.Advantageous embodiments and developments of the invention can be derived from the dependent claims and from the description with reference to the drawings.According to a preferred embodiment of the present invention, it is provided that the first roller has a first profile. The second roller has a second profile. The profiles of the rollers are surface topographies of the circumferential surfaces of the rollers and relate to the course of the extension of the rollers orthogonally to the respective axial direction along the respective axial direction. The profiles are provided in particular for the purpose that the displacement along the axial directions produces a desired course of the gap height and in particular a uniform gap height of the roll gap between the rolls. The first profile and / or the second profile has an S-shape, a 1.5-S-shape or a double-S-shape. It is preferably provided that the first profile and / or the second profile has at least one, two or preferably three inflection points. The first and the second roller are therefore not cylindrical or frustoconical, but rather have regions of different gradient over the roller width. This results in different roller diameters along the roller widths, which have a non-linear course along the axial direction. Nonlinearly also preferably comprises a stringing of several nonparallel linear sections. Depending on the relative position of the rollers along the axial direction, the diameter deviations of the two rollers compensate each other, so that, quite according to the present need, a desired, in particular uniform, gap height can be adjusted in a targeted manner. In particular, it is provided that the profiles each have a polynomial profile, at least third degree, at least fourth or very particularly preferably fifth degree. It is conceivable for a bombage to be superimposed on the S-shape, the 1,5-S-shape and / or the double-S-shape. An S-shape has two opposing curves. A 1,5-S shape has three opposing curves. A double-S shape has four opposing curves.According to a further preferred embodiment of the present invention, it is provided that the first profile and the second profile are designed such that, in a relative position of the first or second roller, the roller nip has a desired and in particular a uniform nip height along the axial direction when the entanglement device entanglements the first and the second roller about the entanglement axis by an entanglement angle, wherein the entanglement angle is preferably not zero. In other words, the entanglement of the rolls is already taken into account in the shaping of the first profile and the second profile. This makes it possible to compensate for deviations from the desired profile of the gap height, which can be entered by the interleaving itself or cannot be compensated by the interleaving alone.According to a further preferred embodiment of the present invention, it is provided that the displacement of the first roll along the first axial direction is associated with a displacement of first roll journals of the first roll by first main bearings of the calender. In other words, at least parts of the first main bearings remain fixed when the rollers are displaced along the axial direction. In particular, it is also provided that the displacement of the second roll along the second axial direction is associated with a displacement of second roll journals of the second roll by second main bearings of the calender. It is conceivable that the calender has first axial adjusting means for displacing the first roll along the first axial direction and / or second axial adjusting means for displacing the second roll along the second axial direction.For this purpose, it is preferably provided that the first main bearings have cylindrical roller bearings, wherein the displacement of the first roller along the first axial direction causes a displacement of an inner ring of the first main bearing, wherein it is in particular provided that rolling bodies and / or an outer ring of the first main bearing are not displaced during the displacement of the first roller along the first axial direction. In this case, for example, the first axial adjusting means can bring about the displacement of the first roller journal.It is furthermore conceivable for the second main bearings to have cylindrical roller bearings, wherein the displacement of the second roller along the second axial direction causes a displacement of an inner ring of the second main bearing, wherein it is provided in particular that rolling bodies and / or an outer ring of the second main bearing are not displaced during the displacement of the second roller along the second axial direction. In this case, for example, the second axial adjusting means can bring about the displacement of the second roller journal.It is conceivable that the rolling bodies of at least one of the first main bearings and / or the second main bearings are guided only on the respective outer ring. As a result, the rolling bodies would not slide along. It is furthermore conceivable that the rolling bodies of at least one of the first main bearings and / or the second main bearings are guided only on the respective inner ring. As a result, the rolling bodies would also slide. It is furthermore conceivable that the inner ring of at least one of the first main bearings or second main bearings is formed by the first roller journal. For this purpose, the first roller journal is preferably hardened in the region of the respective bearing.Preferably, it is provided that the first roll and / or the second roll of the calender are heated. As a result, the calender is even more suitable for use in the production of electrodes. The first roller and / or the second roller can be heated, for example, electrically or inductively via induction coils. However, it is also conceivable for the first and / or the second roller to be heated with steam, which is guided, for example, through a central bore or through peripheral bores. It is preferred that the first roller and / or the second roller are provided for heating with an oil which flows through the first and second rollers via peripheral bores. Preferably, the first roll and / or the second roll are heated to at least 80° C. and very particularly preferably to at least 100° C.A further subject matter for achieving the object set forth in the introduction is a method for operating a calender, in particular a calender according to the invention, wherein a deflection of the first roll of the calender is compensated by displacing the first roll along the first axial direction and / or the second roll along the second axial direction and by interleaving the rolls such that the roll nip has a desired and in particular uniform nip height. The method according to the invention advantageously makes it possible to calender sheet-like structures, for example in the production of electrodes, with very high precision with very high line forces over a wide range. Even with web widths of significantly more than one meter, the gap height can be adjusted over the entire web width with an accuracy of 1 μm and less and simultaneously calendered with line forces of up to 10,000 N / mm.The features, details and advantages mentioned above in connection with the calender according to the invention likewise relate to the method according to the invention.Further details, features and advantages of the invention are evident from the drawings and from the following description of preferred embodiments with reference to the drawings. The drawings illustrate only exemplary embodiments of the invention, which do not restrict the concept of the invention.The following are shown: FIG. 1 : shows a schematic view of a calender according to an exemplary embodiment of the present invention for carrying out a method according to an exemplary embodiment of the present invention, FIG. 2 : shows a schematic view of the working rolls of a calender according to a further exemplary embodiment of the present invention for carrying out a method according to an exemplary embodiment of the present invention, FIG. 3 : schematic views of the first roll and the second roll of a calender according to an exemplary embodiment of the present invention in different relative positions along the axial direction, and FIGS. 4(a), (b) are schematic views of a rolling bearing of a calender according to an exemplary embodiment of the present invention.FIG. 1 shows a calender 100 according to an exemplary embodiment of the present invention in a side view. The opposite side of the calender 100 shown is constructed in mirror image to the side shown. The calender 100 is provided for calendering a sheet material, not shown here, in particular for producing electrodes. For this purpose, the calender 100 has a first roll 1 and a second roll 2, which can be heated with an oil which flows through peripheral bores (not shown for the sake of clarity) of the rolls 1, 2. The first roll 1 is mounted rotatably about a first axial direction A 1 in a calender frame 10. The second roll 2 is mounted rotatably in the calender frame 10 about a second axial direction A 2. It is conceivable for the calender 100 to have further rolls. However, in the following, the description will be limited to the first roller 1 and the second roller 2 constituting the work rollers of the illustrated embodiments. Between the first roll 1 and the second roll 2 a roll nip 9 is formed, to which the sheet material is fed in the direction of the goods W.The first roller 1 is mounted with first roller journals 3 in first main bearings 5 (see FIG. 4 ). The second roller 2 is mounted with second roller journals 4 in second main bearings. The second main bearings are not shown here, since they are formed analogously to the first main bearings 5.In calendering electrodes, a coated conductive foil is rolled to a thickness of 40 μm to 400 μm with line forces of 500 N / millimeter to 10,000 N / millimeter. The accuracy here plays an important role in the later performance of the electrode. For example, the porosity of the electrode is determined by calendering. Even in the case of deviations of the gap height from 2 μm to 3 μm, inaccuracies are achieved in the production process of the electrode, which inaccuracies can hardly be accepted. The calender 100 according to the invention and the method according to the invention make it possible to compensate for unwanted deflection with deviations of 1 μm or better.If the coated films are calendered between the first roll 1 and the second roll 2, deformations of the rolls 1, 2 inevitably occur. Likewise, the rolls 1, 2 are deformed by temperature differences occurring along the rolls. Here, temperature inhomogeneities of a few degrees Celsius can already lead to deviations of the gap height, which should be avoided. During calendering, especially with larger web widths, this leads to deviations in the nip height, which can no longer be tolerated. In order to compensate for these deviations and to achieve a desired, in particular uniform, gap height, the calender 100 has an entanglement means 7, with which the first and the second roll 1, 2 can be entangled about an entanglement axis V. The entanglement axis V is perpendicular to the first axial direction A 1 of the first roller 1 and the second axial direction A 2 of the second roller 2, and such entanglement by an entanglement angle γ is illustrated in FIG. 2.The entanglement axis V can be situated centrally of one or both rollers 1, 2 or else arranged eccentrically. In FIG. 2, at the top is a central arrangement of the entanglement axis V and at the bottom is an off-central arrangement of the entanglement axis V. The entanglement by an entanglement angle γ which is greater than zero, i.e. a non-parallel arrangement of the first axial direction A 1 and the second axial direction A 2 with respect to one another, results in the nip 9 further away from the entanglement axis V being greater than near the entanglement axis V. In the example illustrated at the top in FIG. 2, the distance of the rolls 1, 2 at the ends of the rolls 1, 2 is greater than in the middle of the rolls 1, 2.For the purpose of intermeshing the rolls 1, 2, the calender 100 is equipped with an entanglement means 7, with which one of the rolls 1, 2 or both rolls 1, 2 can be displaced relative to the calender frame 10 with a directional component perpendicular to the respective axial direction A 1, A 2 and can be rotated about the entanglement axis V. The interleaving may be effected by displacing one or more main bearings. Thus, FIG. 2 shows at the bottom an interlace in which only the first main bearing 5 (not shown) on the right-hand first roller journal 3 has been displaced upwards along the plane of the sheet. The second roller 2 is not displaced here. In the top of FIG. 2, both the first roller 1 and the second roller 2 are rotated about the entanglement axis V, which was effected by displacing all the main bearings of the rollers 1, 2.In order to be able to set the compensation for undesired deviations of the gap height in a better spatially resolved manner and in particular in order to compensate for undesired deviations introduced and introduced by the interleaving, such as overcompensations, the first roller 1 is provided with a first profile P 1 and the second roller 2 is provided with a second profile P 2. The profiles P 1, P 2 are ground into the roll barrels of the respective roll 1, 2 and are formed in such a way that different roll diameters are achieved along the axial direction A. The representations in FIGS. 2 and 3 show the profiles P 1, P 2 greatly enlarged.In the embodiment shown here, the profiles P 1, P 2 have different slopes and show three inflection points. By displacing the first roller 1 and / or the second roller 2 relative to each other along the first axial direction A 1 and / or the second axial direction A 2, the course of the height of the roller gap 9 can be adjusted as a result. This is illustrated in FIG. 3. In FIG. 3, the first roller 1 and the second roller 2 can be seen in three different relative positions. In the relative position shown at the top, the profiles P 1, P 2 run parallel to one another without loading, i.e. without calendering of a sheet material. As soon as a sheet material is calendered, this changes as a result of the application of force which arises during rolling of the sheet material. In order to compensate for this, the first roller 1 and the second roller 2 can be displaced relative to one another.In the relative position shown in the middle, the first roller 1 is displaced to the left and the second roller 2 is displaced to the right. Shown at the bottom is a relative position in which the first roller 1 is displaced to the right and the second roller 2 is displaced to the left. It can be clearly seen in the relative positions shown here how the course of the height of the roll gap 9 changes as a result of the displacement. In particular, this can influence the areas of the roll gap 9 between the outer ends and the center.FIGS. 4(a) to (d) each show a detail of a calender 100, in which one of the first main bearings 5 can be seen. The first main bearing 5 is designed here as a cylindrical roller bearing with an outer ring 5.1, an inner ring 5.2 and rolling bodies 5.3. In the embodiments shown in FIGS. 4(a) and (b), the rolling elements 5.3 are guided laterally by a rolling element guide 5.4, which is connected to the outer ring 5.1. When the roller journal 3 is displaced along the first axial direction A 1 by a first axial actuating element (not shown here), the inner ring 5.2 is also displaced, but the rolling bodies 5.3 are held in position by the rolling body guide 5.4 with respect to the first axial direction A 1 and are fixed with the outer ring 5.1. FIG. 5( c) shows an exemplary embodiment in which the rolling element guide 5.4 is fastened to the inner ring 5.2. With a displacement of the inner ring 5.2 along the first axial direction A 1, the rolling bodies 5.3 are thus also displaced. FIG. 5 (d) shows an exemplary embodiment in which the inner ring 5.2 is formed by the roller journal 3 itself. For this purpose, the roll journal 3 is edge-layer hardened. The rolling element guide 5.4 is again fastened here to the outer ring 5.1, as a result of which the rolling elements 5.4 are not moved along in the first axial direction A 1. The details of the first main bearing 5 shown here also apply to the second main bearings, the inner rings of which are displaced with or without rolling bodies.List of reference numbers:1 first roll 2 second roll 3 first roll journal 4 second roll journal 5 first main bearing 5.1 outer ring 5.2 inner ring 5.3 rolling bodies 5.4 rolling body guide 7 entanglement means 9 roll nip 10 calender frame 19 axial adjusting means 100 calender A1 first axial direction A2 second axial direction P1 first profile P2 second profile W fabric direction γ entanglement angle

Claims

Calender (100) for calendering sheets, preferably for producing electrodes, having a first roll (1) and a second roll (2), wherein the rolls (1, 2) can be displaced with respect to one another along a first axial direction (A1) of the first roll (1) and / or along a second axial direction (A2) of the second roll (2), wherein the calender (100) has an entanglement means (7) for entanglement of the first roll (1) and the second roll (2) about an entanglement axis (V), wherein the entanglement axis (V) is perpendicular to the first axial direction (A1) and the second axial direction (A2).Calender (100) according to Claim 1, characterized in that the first roll (1) has a first profile (P1) and the second roll (2) has a second profile (P2), the first profile (P1) having an S shape, preferably a 1.5-S shape, particularly preferably a double-S shape, and the second profile (P2) having an S shape, preferably a 1.5-S shape, particularly preferably a double-S shape.Calender (100) according to one of the preceding claims, characterized in that the first profile (P1) and the second profile (P2) are designed such that, in a relative position of the first and the second roll (1, 2), the roll nip (9) has a uniform nip height along the axial directions (A1, A2) when the entanglement device (7) interlaces the first and the second roll (1, 2) by an entanglement angle (γ) about the entanglement axis (V).Calender (100) according to one of the preceding claims, characterized in that the displacement of the first roll (1) along the first axial direction (A1) is associated with a displacement of first roll journals (3) of the first roll (1) by first main bearings (5) of the calender (100).Calender (100) according to Claim 4, characterized in that the first main bearings (5) have cylindrical roller bearings, wherein the displacement of the first roller (1) along the first axial direction (A1) brings about a displacement of an inner ring (5.2) of the first main bearing, wherein provision is made in particular for rolling bodies (5.3) and / or an outer ring (5.1) of the first main bearing (5) not to be displaced during the displacement of the first roller (1) along the first axial direction (A1).Calender (100) according to Claim 4 or 5, characterized in that a displacement of the second roll (2) along the second axial direction (A2) is associated with a displacement of second roll journals (4) of the second roll (2) by second main bearings (4) of the calender (100), the second main bearings (6) preferably having cylindrical roller bearings, the displacement of the second roll (2) along the second axial direction (A2) particularly preferably causing a displacement of an inner ring of the second main bearing (6), it being provided in particular that rolling bodies and / or an outer ring of the second main bearing (6) are not displaced during the displacement of the second roll (2) along the second axial direction (A2).Calender (100) according to one of the preceding claims, characterized in that the first roll (1) and / or the second roll (2) are heated.Method for operating a calender (100), in particular a calender (100) according to one of the preceding claims, wherein a deflection of the first roll (1) of the calender (100) is compensated for by displacing the first roll (1) along the first axial direction (A1) and / or the second roll (2) along the second axial direction (A2) and by interleaving the rolls (1, 2) such that the roll nip (9) has a wanted and in particular uniform nip height.

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