FI68280C - Device for magnetic equalization of the deflection of a rotary body, especially a calender roll - Google Patents

Description

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• (45) ^ ^ (51) Kv.lk. «/ Lnt.CI. * D 21 G 1/02 (21) Patent application - Patentansöknlng 802411 (22) Application date - Ans & knlngsdag 01, 08.80 (23) Initial cloud - Glltighetadag 01. 08.80 (41) Tullut (ulklseksl - Bllvlt off en tl ig 15.02.-81

Patent * and National Board of Registration / 441 Date of publication and publication

Patent and registration authorities '' Ansökin utltgd och utl.skrlften publlcerad. U4. 05 (32) (33) (31) Privilege requested - Begärd priority 14.08.79

Republic of Germany-Förbundsrepubliken

Tyskland (DE) P 2932857.2 Proven

Styrkt (71) Kleinewefers GmbH, Kleinewefers-Kalanderstrasse, 4150 Krefeld,

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Josef Pav, Krefeld, Hans Weidinger, Putzbrunn,

Werner Ehm, Dachau, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (74) Oy Kolster Ab (54) Device for magnetic compensation of the deflection of a rotating body, in particular a calendar roll - Anordning för magnetisk utjämning av nedböjningen hos en roterande kropp, speci

The invention relates to a device for magnetically compensating the deflection of a body of at least partially magnetizable material rotating about an axis, in particular of a calender roll, by means of a magnet-having a circumferentially circumferentially circumferential pole surface, leaving an air gap between them and the rotating body.

The bodies rotating about the axis, e.g. the calender rolls, bend due to their own weight and due to the compression pressure of the adjacent rotating bodies and the upper rollers, respectively. In the case of long and heavy calender rolls or similar press rolls for pressing a rolled or smoothed product, eg paper, films or textiles, to a uniform thickness over the entire width of the roll, this deflection may be so great that 2 68280 uniform rolling of the rolled or smoothed product is not guaranteed. In the case of such rollers, due to the deflection, the compression pressure on the rolled or smoothed product in the middle of the roll is then higher than at both ends of the roll. Correspondingly, the rolled or smoothed product becomes thinner in the middle of the roll than at the ends of the roll.

In order to achieve a uniform compression pressure and thus a uniform thickness of the rolled or smoothed product over the entire width of the roll, it is known in connection with the calender rolls to produce a hydraulic pressure field between the rotating roll jacket and this penetrating torsionally resistant support shaft. However, this results in satisfactory results only if the rotational speed of the roller is low, whereas as the rotational speed increases due to the viscosity of the hydraulic fluid, the pressure field between the shaft and the roller casing is destroyed so that deflection compensation is no longer satisfactory.

It has further been proposed in connection with the rollers of a calender having a perforating fixed support shaft to accommodate deflection on the underside of the stationary shaft in the axial direction, which raises the roll shell against the axis. However, as the roll shell rotates, large eddy current losses occur, which partially cancel out the magnetic compensating force and further lead to uncontrolled heating of the roll shell.

Furthermore, in connection with magnetic bearings for magnetic bearing of a shaft, it has been proposed to fit a magnetic body which supports electromagnets in the circumferential direction, the hub surfaces of which have a circumferentially varying polarity.

(SKF Technische Information No. 299, 12 April 1977). In principle, such a bearing would also be suitable for compensating for the deflection of rotating bodies such as calender rolls. In this case, however, in connection with the rotation of the corresponding magnetically supported bearing part, varying polarities of the hub surfaces occur, corresponding continuously in the circumferential direction to the change of direction of the field, which in turn leads to eddy current losses. Although these eddy current losses can be reduced by means of a tinned iron return barrier, this is not completely reversed.

3,68280

It is an object of the invention to provide a device for magnetic deflection equalization which is simply constructed and which operates without disturbing the rotating body with high efficiency and low eddy current losses and which can also be successfully used at high rotational speeds.

According to the invention, this object is solved in such a way that the polar surfaces running in the circumferential direction of the magnetic body in each case have the same polarity and the axially adjacent polar surfaces have opposite polarities.

Although magnetic bearings are known, as mentioned above, the device according to the invention is characterized in that there is no reversal of polarity in the circumferential direction of the hub surfaces. The pole surfaces preferably extend in the circumferential direction over the largest possible circumferential angle, so that in this case there is no change of direction of the field in connection with the rotation of the rotating body. Only relatively small eddy currents are induced, so that the rotating body also does not heat up uncontrollably. The device according to the invention functions as a device with substantially low losses for compensating the magnetic deflection with approximately the circumferentially varying polarity of the magnetic poles.

The magnetic body preferably has a stationary core with annular grooves cut in the circumferential direction, in which the windings of the electric coils are placed. The pole surfaces then always extend according to the extent of the windings in the circumferential direction over a certain maximum circumferential angle. The hub surfaces having the same polarity in the circumferential direction are preferably divided into several blocks, so that approximately the entire circumference has three hub surfaces formed by windings, each of which has a circumferential angle of 120 °. In this case, one pole surface is arranged symmetrically around a vertical plane on the underside of the magnetic body, whereby the magnets thus formed act essentially as support magnets for the rotating body to be supported. Both other pole surface parts then function essentially as side or compensating magnets, with the help of which the deformations of the rotating body can be compensated, e.g. by pressure supply. If 4 68280 calender rolls are used as the rotating body, in which the roll jacket is rotatably mounted on a stationary support shaft, then the support shaft is made into a magnetic body, whereby annular grooves are turned in the circumferential direction and the grooves The coils of electromagnets are then placed in these grooves in a conventional manner. If, as mentioned, the hub surfaces of the magnetic body are divided in the circumferential direction so that each hub surface comprises a single winding, then the windings of the individual coils can be attached to the contact points by means of a winding head holder made of magnetic material.

In order to precisely adjust the deflection compensation, it is advantageous if the coils of the magnetic body can be controlled independently of one another. This is also true for coils that form individual hub surfaces in the circumferential direction. The coils located side by side in the axial direction of the magnetic body can then be combined into groups, which as such can then be controlled separately in each case. When the axis of rotation of the rotating body and the central axis of the magnetic body coincide and a constant air gap is obtained for the entire circumference of the rotating body by magnetic deflection compensation, the lower support magnet coils must

However, the provision of a constant air gap to compensate for the deflection on the underside of the rotating body can also be supported so that the central axis of the magnetic body and the axis of rotation of the rotating body do not coincide but are mounted slightly eccentrically so that the axis of rotation of the rotating body is vertically above the central axis. In connection with the compensation of the magnetic deflection, the air gap between the magnetic body and the rotating body is then smaller on the lower or carrier side than on the upper side. In this case, the support magnets and the other side and control magnets may be activated to the same strength. Since the attraction in the sauna is proportional to the inverse of the square of the air gap in the flow, the upward attraction is consequently at the same time in connection with smaller eddy current losses in the rotating body.

68280

What the solutions of the invention mentioned so far have in common is that no or very little eddy currents are induced in the rotating body. Nevertheless, it has also been possible to induce eddy currents in a controlled rotating body to bring it to the desired temperature to be observed.

This can take place, for example, by different activation of the individual windings on the hub surfaces in the circumferential direction, so that a controlled field generation and field dissipation is achieved during the rotation of the rotating body, and this is used to heat the rotating body almost completely. Another possibility is to orient the coils in one circumferential direction of the magnetic body in opposite directions, so that a change of hub takes place in the circumferential direction and thus also a controlled change of direction of the field in connection with the rotation. In addition, said winding head holders, which act to bypass the hub surfaces belonging to the individual coil parts in the circumferential direction, may have a gap of a certain size so that the individual hub surfaces are separated from each other. Also, controlled eddy currents are thus induced in the rotating body, leading to controlled heating. The supply of coils with alternating current is also suitable for this purpose. Of course, the mentioned possibilities can also be combined. Thus, a simply adjustable heating of the rotating body can be achieved.

Other embodiments and advantages of the invention will become apparent from the subclaims, together with the following description, in which two embodiments of the invention are described in more detail in connection with the drawing. Fig. 1 shows a schematic longitudinal section of a calender roll comprising a device for preventing deflection according to the invention, Fig. 2 a cross-section along the line II-II in Fig. 1, Fig. 3 a schematic diagram and Fig. 5 is a schematic cross-section of another embodiment of a device for magnetic compensation of a rotating body according to the invention.

68280

The calender roll 1 consists of a stationary support shaft (magnetic body) 2 and a surrounding sheath 3.

This stationary shaft 2 is fastened on both sides to the bearing brackets 4, while the roller shell 3 is supported by a rotatable shaft by means of suitable bearings, e.g. rolling bearings 5. The support shaft and the roll shell are each made of suitable steel.

The axis of rotation 6 of the roll shell 3 shown in Fig. 2 does not coincide with the longitudinal central axis 7 of the stationary support axis, but is located at a small distance vertically above it. Due to this eccentric position of the support shaft and the roll shell, a circumferential gap 8 is created between them, which is narrower in the lower region of the calender roll than in the upper region.

The stationary bearing shaft 2 has annular grooves 9 with a small depth in the circumferential direction. In each case, for the angular distances of 120 °, transverse grooves 10 in the axial direction of the bearing shaft are arranged between adjacent annular grooves, connecting two adjacent annular grooves. One of these groups of transverse grooves 101 runs on the upper side of the support shaft 2, while the other, in Fig. 1 front group of transverse grooves 10 extends over the length of the shaft at angular distances of 60 ° on the other side of the vertical plane (Fig. 2). The windings 11 of the coils (magnetic bodies) 12 are placed in the annular and transverse grooves 9 and 10, respectively, so that the windings of one coil are in two adjacent annular grooves and in two adjacent transverse grooves. Thus, hub surfaces 13 ^ _3 are formed between these annular and transverse grooves, which are oriented in the circumferential direction of the carrier axis. Coils whose windings are front and between the rear cross grooves 102 and the group 10 in the ring groove 9 are hereinafter referred to as support coils 12, while coils with windings between the front group of the cross grooves 102 and the upper group of the cross grooves 10 are referred to as front side coils 122. and coils whose windings are in the annular groove between the upper group of transverse grooves 10 ^ and the rear group of transverse grooves 103 are referred to as rear side coils.

The fitting of the coils to the support shaft 2 is shown schematically in Figure 4.

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The support and side coils are supplied with voltage via a stationary support shaft, while, for example, corresponding wires are placed in the groove 22, as shown for the support coils 12.

The windings in the annular grooves 9 are covered with a groove rim 14 of magnetically permeable material, in contrast to which U-shaped coil head restraints 15 of magnetic material are arranged in the cross grooves and are screwed with the fastening shaft 2. The surface of the winding head holders is firmly fitted to the upper surface of the support shaft 2.

The support and side coils 12 ^ and 122 and 12 ^, respectively, which are in the circumferential direction are supplied with energy so that the respective pole surfaces have the same polarity and the axially adjacent groups of support and side coils all have pole poles of opposite polarity. Figure 1 shows the hub surfaces between the first two ring grooves on the left side of the support roller as south poles 5, while the adjacent hub surfaces are shown as north poles N. Axially the next hub group is again the south hub. over.

As schematically shown in Fig. 3, the support coils of the support magnets are divided into groups to be controlled separately from each other, and in this case into five groups GTn to GT1, each group having four coils. The coil groups are in each case supplied via the support magnet control devices 16 at a direct voltage, the support magnet control devices being connected to a 380 ° three-phase AC power line. The front and rear side coils are in each case controllable by means of their own side magnet control devices 17, whereby these side magnet control devices are likewise connected to the same line. Of course, it is also possible to connect the side coils to several groups and control them individually. The support magnets 16 and the side magnets 17 the same or desired desired thickness. At the same time, the side magnets are adjusted to compensate for possible deformations of the roll shell caused by pressure loads and the like. The support and side coils can also be further adapted and guided in such a way that the load on the rolling bearing 5 between the roller shell and the support shaft is reduced. In this case, the roller casing can be mounted on the support shaft even freely, in which case the rolling bearing 5 is no longer necessary.

Since the support shaft also bends under its own weight and is subjected to traction when the magnets are further connected, the shaft or roller sheath can be made into a rotation paraboloid with a concave contour, as shown by dashed line 21 in Fig. 3. When the magnets are connected, a constant gap for the entire length of the roll.

As shown in Fig. 2, the U-shaped holders 15 in cross-section can also be made of two pieces, as shown for one winding head holder 15 '. In this case, a gap is left between the individual parts of the winding head holder, which cuts off the hub surfaces of the circumferentially adjacent coils. Thus, in connection with the rotation of the roll shell, eddy currents are induced here, by means of which the roll shell can be heated. The heating of the roll shell and the control of the roll temperature can be further achieved by the above-mentioned measures, in which case the support and side coils are either activated with different intensities, polished differently or fed via magnetic control devices with alternating current.

Figure 5 schematically shows another exemplary embodiment. In this case, the rotating body 3 'is in the form of a horseshoe surrounded by a stationary magnetic body 21, the coils 12', 1221, 12 '' being produced in the grooves on the inner surface of the magnetic body in order to produce bearing and lateral forces. The support coils 12 ^ 'in this case are called the coils at the top of the drawing. The quality and fitting of the coils to the magnetic body and also the principle of operation correspond to the first embodiment described above, so that a closer description is unnecessary here.

Claims (21)

Apparatus for magnetically compensating for the deflection of a body rotating about an axis at least partially of magnetizable material, in particular a calender roll, by means of a magnetically adjacent circumferentially spaced-apart na-faces, leaving an air gap between them and the rotating body, characterized in that the magnetic body (2, 12) the circumferential pole surfaces (13) in each case have the same polarity (S, N) and the axially adjacent pole surfaces have opposite polarities. Device according to claim 1, wherein the magnetic body (2, 12) consists of a core (2) and magnetizable electric coils (12) wound thereon, characterized in that the electric coils (12) of the circumferential pole surfaces have the same polarity-generating winding direction. Device according to claim 1 or 2, wherein the magnetic body (2, 12) pierces the rotating body (roll cover (3)), characterized in that the rotating body (3) is rotatably mounted on the magnetic body (2, 12) by means of bearings (5). through. Device according to one of Claims 1 to 3, characterized in that the magnetic body (2 ', 12') completely or partially surrounds the rotating body (3 ') in the circumferential direction. Device according to one of Claims 1 to 4, characterized in that the hub surfaces (13) are formed in the circumferential direction of the magnetic body (2, (12) by a plurality of parts (13, 132, 13) which can be magnetically crosslinked by means of inner bodies (winding head holders 15). Device according to one of the preceding claims, characterized in that the magnetic body (2, 12) has circumferentially directed annular grooves (9) and transverse grooves (10) connecting them inside the electric coils (12). 10 68280 Device according to Claim 6, characterized in that the electric coils (12) of the circumferentially extending hub surfaces (13) arranged in the annular and transverse grooves (9 and 10, respectively) are in each case connected by a plurality of circumferentially connected individual coils (12 ^, 122, 12 ^). . Device according to Claim 7, characterized in that the coils (12 ^, 122, 12 ^) of one pole surface (13) adjoining one another extend their winding length in one part in a common transverse groove (10). Device according to Claim 8, characterized in that winding head holders (15) are arranged in the transverse grooves (10) between the annular grooves, which receive the winding ends of two circumferentially adjacent coils (12). 9,68280 Device according to one of Claims 6 to 9, characterized in that for each hub surface (13) there are three individual coils (12 ^, 122, 123) in the circumferential direction, one coil (support coil 12 ^) being arranged symmetrically with respect to the deflection plane and the other coils ( side coils 122, 12 ^) are fitted to both sides of the first coil in connection therewith. Device according to one of the preceding claims 6 to 10, characterized in that the coils adjacent in each case in the axial direction of the magnetic body (2, 12) are connected into groups of coils which can be controlled independently of one another. Device according to one of the preceding claims 6 to 11, characterized in that the circumferentially arranged single coils (12 ^, 122, 12 ^) and the coil groups (GT ^ - GT, -) - can be controlled independently of one another. Device according to one of Claims 10 to 12, characterized in that at least the side coils (122, 12 ') and the side coil groups, respectively, can be controlled jointly and independently of the support coils (12 ^) and the support coil groups (GT ^ - GT ^), respectively. Device according to one of Claims 6 to 13, characterized in that the coils (12 ^, 122, 12 ^) belonging to the axially adjacent hub surfaces (13 ^, 132, 133) of the magnetic body (2, 12) are controllable from one another. independently. 11 68280 Device according to one of Claims 5 to 14, characterized in that the circumferentially bridging inner parts or the winding head holders (15 ') of the hub surface parts (13, 132, 13) are cut off and separate the hub parts in the circumferential direction. Device according to one of the preceding claims, characterized in that the coils (12 ^, 122 »12 ^) belonging to one hub surface (13) in the circumferential direction can be controlled separately in order to heat the rotating body (3). Device according to Claim 16, characterized in that at least some of the coils (12 ^, 122, 12 ^) can be controlled by an alternating voltage. Device according to one of Claims 16 and 17, characterized in that the circumferential coils of the magnetic body (2, 12) can be guided in such a way that the respective pole surface parts (13, 132, 13) have different polarities in the circumferential direction. Device according to one of the preceding claims, characterized in that the axis (7) of the magnetic body (2, 12) and the axis of rotation (6) of the rotating body (3) are eccentric (£). Device according to Claim 19, characterized in that the axis of rotation (6) of the rotating body (3) extends in its plane of deflection above the axis (7) of the magnetic body (2, 12). Device according to one of the preceding claims, characterized in that one of the opposing surfaces of the magnetic body (2, 12) and the rotating body (3) is made a concave rotational paraboloid (21) so as to provide a constant air gap (8) during effective magnetic deflection compensation. between the magnetic body and the rotating body in the main area of action of the support magnets formed by the support coils (12 ^) and the support coil groups (GT ^ - GT ^), respectively. 12 68280