FI113556B - The thermo roll - Google Patents

Description

113556 *

The present invention relates to a roll used in connection with paper or similar processing, in particular a calender heated roll, i.e. a so-called roll. ter-5 motel heated by a suitable heating method. The invention also relates to a nip between the aforementioned thermal roller and its counter roll.

Heated rollers are known e.g. EP 333688, US 4,658,486 and US 4,920,623. The heating of the rolls is usually done by circulating hot steam or liquid inside and out of the roll. An arrangement is known from EP 0967324 and the corresponding DE 19828156 in which a nip is formed between a deflection compensated roll and a heated belt loop.

15 Electromagnetically heated rolls are known e.g. from F 73260 corresponding to US 4,675,487 and US 5,895,598 corresponding to DE 197 43 724. F 73260 discloses a roll which is heated by electromagnetic induction heating by applying magnetic flux to the roll casing by means of a magnetic stiffener device mounted outside the casing, and a magnetizing current of to provide a sufficiently low penetration depth of the heating effect. US 5,895,598 discloses a roll which is heated by electromagnetic induction heating such that magnet strips are mounted inside the roll casing. Roller weight: ··: 25 passages have channels with heated medium, for example; ·: water.

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The problem with known solutions is the high cost of the equipment required for recycling the heating medium. Often, processes require 30 arrangements to heat the thermal roller and cool its counter-roll or pumice-compensated roll, thereby consuming energy for both heating and cooling. In open belt rotation, it is very difficult to keep the oil inside the belt rotation, and it easily sprays outside the belt rotation. In addition, due to the thickness of the roll casing, ···. The 35 rotating mass is large, which causes vibration problems. Known heating solutions using • ♦ induction heaters are expensive and the efficiency of induction heaters located outside the roller I 1 «• · · · ♦ 1 • 4 t 2 113556 is poor. However, when using induction heaters located inside the roll, the diameter of the roll must be relatively small.

The thermal roller of the invention is an improvement over the prior art. The thermal roller according to the invention is characterized in that it comprises a sliding shoe inside the thin flexible sleeve which is arranged to contact said jacket. The nipple according to the invention is characterized in that it is formed between a flexible sheath pressed on the face of a slider of a thermal roll and a soft surface roll. As used herein, the term sliding shoe face refers to the surface of the sliding shoe that is in contact with the jacket of the thermal roller.

The thermal roller of the invention has several advantages:

The basic heat of the roll is obtained from frictional work, the losses are very well utilized, the I solution eliminates the need for expensive fluid recycling machine and tubing, 20 thermal stresses,: * 1. i - the efficiency of the induction heater is high and a liquid inside the roll can be used to cool it; ··· 25; * ··. - the bend compensation of the nip roller pair can be treated. a cheap non-compensated roll, • · '30 - a spare roll is not required, only a replaceable sheath portion is required, and vibration problems are substantially reduced as the rotating mass is significantly reduced.

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The thermal roller according to the invention is used in paper handling, in particular ···. 35 times on the calendar. The invention can be used in both on- and off-machine processes. The calender generally comprises overlapping rolls between which nipples through which the paper passes are formed. The calender may also have only one pair of rolls or two or more pairs of rolls, whereby the nip / nips 3 113556 are formed between the rolls of the pair of rolls / rolls. The purpose of calendering is to affects paper thickness and reduces thickness variations and improves surface properties such as smoothness and gloss.

The invention comprises a so-called. kenkätermotelan. The jacket of the thermal roll of the invention is a thin, tubular metal jacket. The thickness of the sheath is up to 15 mm, generally up to 10 mm, preferably 1.0 to 1.5 mm. The diaper is substantially non-compressible. The diaper is arranged to rotate about a stationary body. Due to the thinness of the jacket, the mass rotating around the run-10 goon is small.

A sliding shoe is mounted on the roll body to hold the metal sheath in its proper shape in the nip. The face of the sliding shoe is convex, so that the roll shell is not subjected to fatigue stress, which is a problem with tees having concave sliding shoes.

The sliding shoe can be loaded with a suitable nip pressure! sex with the load elements between the body and the slipper. The fluid inside the shaft, such as lubricating oil, reduces the friction between the sliding 20 shoes and the rotating metal sheath. However, there is always some friction between said surfaces and the frictional work is converted into heat which can be utilized in the solution of the invention to maintain the basic heat of the roll.

I · «« · * · •: ··: 25 The liquid inside the roll shell, such as lubricating oil, can be very heat. special durable oil. The amount of liquid inside the roll is at least. '···. 25% of the volume inside the roll, but the space inside the roll may also be completely filled with liquid. However, there must be ::: enough fluid to lubricate the roll diaper and slip shoe. ··· * 30. The heat due to the frictional work between the roll shell and the sliding shoe heats the lubricating fluid, which is not recycled to be heated outside the roll, but through the thin metal sheath to be used to heat the outer surface of the roll. The heat generated can be utilized to the full and with appropriate additional heating, such as in-! ··. 35 duct heating or electric resistors, the need for additional heat is covered.

"In this case, the power required from a heater, such as an induction heater or an electric resistor, is low because the basic heat is otherwise produced.

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It is possible that the liquid is circulated outside the roll for reasons other than heating, for example purification, such as filtration.

5 When an induction heater is mounted on the roll body as an auxiliary heater, it heats the ferromagnetic, thin metal sheath. The induction heater comes close to the nip formed by the thermal roller and its counter roll, which results in low heat losses. Heat is easily transported through the thin metal sheath to the paper web passing through the nip. The induction heater 10 comprises an electromagnetic coil (s) which is cooled by the liquid inside the roll, whereby the liquid warms up and this heat can also be utilized.

The heating capacity of the induction heater is based on the electromagnetic wheel-15 reviratory and hysteresis losses. When a variable magnetic field is applied to the conductive material, eddy current and hysteresis losses occur in the material and the material warms up. The power of eddy currents depends! about the intensity of the magnetic field and the frequency of change of the magnetic field according to the following formula 20 P = B2 f2 where P = the power of the eddy currents B = the intensity of the magnetic field f = the frequency of changing the magnetic field

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I · · ·: ··: 25 The magnetic field lines form a closed curve. Ferromag-. ·. ethical substance, the most famous of which are iron, cobalt, nickel and their. · · ·. alloys, attracts the lining. The lines then pass through a thin metal sheath of the thermal roll. The frequency of the magnetizing current is selected according to the thickness of the jacket of the thermal roll, so that the thinner the jacket · * '30 is, the higher the frequency of the magnetizing current is used.

In the following, the invention will be explained in more detail with reference to the accompanying figure, in which * ···. Figure 1 shows a pair of rolls formed by a shoe thermo roll and a polymer roll.

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As shown in Figure 1, the thermal roller 1 comprises a sheath 2, a body 3, a loading element 4, a sliding shoe 5, and an induction heater 6. The substantially cylindrical sheath 2 of the thermal roller 1 is metal, e.g. steel, and , preferably 1.0-1.5 mm. The casing 2 may be coated on its outer surface with a wear-resistant coating, for example tungsten carbide. The sheath 2 is formed of ferromagnetic material.

The shell 2 has a body 3, a loading element 4, a sliding shoe 5 and an in-10 duct heater 6. There is a convex sliding shoe 5 against the inner surface 2a of the roll shell 2, which is uniform over the entire length of the roll shell 2. The convex shape of the sliding shoe 5 ensures that the diaper 2 is not subjected to fatigue stress and therefore the diaper 2 is long-lasting. The sliding shoe 5 is a substantially uniform, solid body. Between one side 3a of the body 3 and the sliding shoe 5 is a loading element 4 for loading the sliding shoe 5 against the inner surface 2a of the sheath 2. The loading element 4, which are located several across the width of the roll, may be a known power unit 20, for example a hydraulic cylinder. The convex surface 5a of the sliding shoe 5 has a substantially cross-sectional shape similar to a portion of a circular circumference having the same diameter as the sheath 2.

·: There is lubricating oil (not shown) inside the sheath 2 of the thermal roller 1, • which lubricates the contact surface between the convex end face 5a of the sliding shoe 5 and the rotating sheath 2. Convex face 5a and rotating sheath 2, ··. contact produces frictional work which becomes heat by heating the lubricating oil. The heat of the lubricating oil is easily due to the thin metal sheath 2; through heating the outer surface of the thermo roll 1, whereby the heat can be used for '··' 30 calendering.

»·: The heat from frictional work is usually not enough to heat the thermal roller 1 * ·, but additional heating is required, for example induction heaters: · .. or electrical resistors. In Fig. 1, additional heating is provided by an induction heater 6 located near the inner surface 2a of the diaper 2, preferably in the direction of rotation of the diaper 2, shortly before the sliding shoe 5, whereby the portion of With W.

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The induction heater 6 comprises cores arranged on the other side of the shoe thermal roller 1, on the inside of the sheath 2, arranged in the same horizontal row and surrounded by a magnetizing coil. The heart is usually iron.

5 The coil may be specific to each core or may be common to multiple cores. However, the core inside the magnetization coil is not necessary, but the induction heater 6 can be formed from the magnetization coils alone. The heart affects the efficiency of the induction heater, but it also increases the cost.

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The portion with one coil can be adjusted as desired and thus, for example, zone-controlled regulation of the surface temperature of the thermal roller 1, e.g. to profile the gloss of paper.

The core and coil form an electromagnetic coil arranged to generate a magnetic field. The lines of the magnetic field form a closed curve and pass through a portion of the ferromagnetic metal sheath 2, heating it by heating the material due to eddy current and hysteresis losses in the sheath 2.

To control the axial temperature profile of the roll 1, an excitation current of variable intensity and / or frequency is applied to the core of the coil. There is a small gap between the induction heater 6 and the inner surface 2a of the sheath 2 through which the lines of the magnetic field forming the closed curve pass. The lubricating oil inside the roller 1 cools the electromagnetic coils 25, whereupon the lubricating oil warms up and the heat is applied to the roller 1. via a thin jacket 2 for use in a paper processing process.

The jacket 2 is arranged to rotate about a stationary body 3.

In this case, there is a bearing or similar arrangement between the skirt 2 and the body 3 and the ends of the body 3 are connected to a suitable support structure supporting the shoe thermo roll 1. Shoe thermo <# ·: roller 1 has actuators at one or both ends and a force intermediate! ·. through the end flanges of roll 1. The drives may also be located within 35 rollers.

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As shown in Fig. 1, a preferred embodiment of the invention is one in which the nip N is formed with a shoe thermo roll 1 by a non-bending roll 7 having, for example, a cast iron sheath 7a and a polymeric coating 7b on the outside. Hereby, the deflection compensation of the pair of rolls forming the nip N is arranged on a shoe thermo roll 1, whereby the pair of rolls forming the nip N is a cheap solution. The deflection compensation can be implemented by applying to the sliding shoe 5 with individually adjustable forces the loading elements 4.

The foregoing is not limiting of the invention, but may vary within the scope of the claims. It is possible that the jacket of the thermal roller is other than substantially cylindrical. It may be, for example, a belt rotating about two rolls, the sides of which are closed by a suitable arrangement. The induction heater may also be located outside the thermal roll casing.

15 The slipper may have discontinuities. In addition to the induction heater, there may be other heaters inside the roll, for example electrical resistors. The liquid substance inside the roll may be any suitable liquid. The thermal roll roll counter roll may also be a second shoe roll having a casing made of polymeric material, for example polyurethane, for example a shoe roll known from the OptiDwell ™ calender. In addition to paper, the invention can also handle different types of board.

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Claims (17)

1. Thermal rolls (1) used in the processing of paper or the like, in particular a thermal roll of a calender which is arranged to be heated, and which thermal roll (1) comprises liquid medium inside its jacket (2), characterized in that inside the thin, flexible manifold (2) it comprises a sliding shoe (5) which is arranged to move the meninto (2). 2. A thermal roller according to claim 1, characterized in that the end surface (5a) of the slide 10 (5) is convex. Thermal roller according to claim 1 or 2, characterized in that the sliding shoe (5) is arranged to press against the inner surface (2a) of the sheath (2) to provide a suitable nip pressure. 15 Thermo-roll according to any of the preceding claims, characterized in that the sliding shoe (5) is arranged to be loaded zonewise in the longitudinal direction of the jacket. 5. Thermal rolls according to any of the preceding claims, characterized in that the end caps (2) closed with end pieces are at least partially filled with a liquid medium. i ·. : 6. Thermal roll according to claim 5, characterized in that the liquid medium is not circulated outside the roll. * 7. Thermal roll according to any of the preceding claims, characterized in that the frictional work caused by the contact between the end surface (5a) men (2), who are ... in 'arranged to heat men' (2). «» «» ». ·! : 8. Thermo-roll according to any of the preceding claims, characterized in that the material of its jacket (2) is metal. 35 v : 9. Thermo-roll according to claim 8, characterized in that the material: * *: of male material (2) is a ferromagnetic material. 11 113556 Thermo-roller according to claim 8 or 9, characterized in that the thickness of the material of the sheath (2) is at most 15 mm, preferably 1.0 - 1.5 mm. Thermal roller according to any of the preceding claims 8-10, characterized in that the auxiliary heating of the roller is arranged with at least one induction heater (6). 12. Thermal roller according to claim 11, characterized in that the induction heating apparatus (6) is an electromagnetic coil comprising at least one magnet winding. Thermal roller according to claim 11 or 12, characterized in that the induction heater (6) is located inside the jacket (2) of the thermal roller (1). A nip (N) formed by two rollers (1, 7) of a paper processing device or the like, especially of a calender in which the nip (N) is heated at least one abutment surface, characterized in that it is formed between a flexible jacket (2) pressed by the end surface (5a) of a sliding shoe in the thermal roller (1) and a roller (7) with a soft surface. 15. A nip according to claim 14, characterized in that at least one of the contact surfaces forming the nip (N) is heated by an induction heater (6). 16. A nip according to claim 14 or 15, characterized in that the bombable roll of the nip is a thermal roll (1). * ·> · A nip according to any of the preceding claims, characterized in that the roller (7) has a soft surface of a shoe roller, the sheath of which is in a:, '': form of an elastic band which is passed over the shoe. • · • »·» I (• ·> · • I »· * 9 * ·