JPS6353676B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an induction heating roller device.

For example, it is well known that rolls such as hot calender rolls, embossing rolls, and thermal bonding rolls are used in the continuous hot rolling process of sheet materials such as plastics, paper, cloth, nonwoven fabrics, metal foils, and web materials. There is. Usually, this type of roll has two rolls, A and A, as shown in Figure 1.
B may be combined as one set, or one roll and an opposing elastic roll may be used as one set. In any case, the web or sheet is nipped between both rolls and heated by a hot roll.

By the way, when heating with this type of hot roll, the accuracy of the heating temperature distribution of the roll is an important factor in order to apply a constant and uniform nip pressure to the material. In other words, for example, if a hot calender roll with a diameter of 500 mm has a surface temperature difference of 10°C, a difference in thermal expansion of about 0.05 mm will occur. It may seriously affect the quality of the product.
Therefore, it is required that the surface temperature of the roll be uniform and uniform. In order to solve this problem, a sealed hollow chamber is provided in the thick part of the peripheral wall of the roller, and a gas-liquid two-phase heating medium is sealed therein.
The latent heat is used to make the surface temperature distribution of the roll uniform, and it has already been put into practical use in many cases.

However, even if it is possible to equalize the surface temperature of the rolls in this way, the above-mentioned equalization of the nip pressure is still not sufficient. This is because when a load is applied to the roll to pressurize the product to be processed, the load causes the roll to deflect. This type of deflection creates a gap between the pair of rolls near the center along the axial direction of the rolls. This tendency is true for rolls A and B.
This becomes noticeable when a load is applied to each rotating shaft so that the rotating shafts C and D approach each other.

Crown rolls have been put into practical use to solve this problem. As shown in Figure 2, this is a trapezoidal or arcuate shape in which the outer diameter of the center of rolls A and B is larger than that of both ends by an amount commensurate with the amount of deflection. , this allows the deflection when a load is applied to be corrected.

Even if this makes it possible to equalize the nip pressure, in practice the outer periphery of the roll must be machined into a trapezoidal or arcuate shape depending on the amount of deflection, which is extremely troublesome. And high precision is required. In addition, the amount of deflection varies depending on the magnitude of the load, whereas the machined shape remains unchanged. Therefore, depending on the magnitude of the load, the nip pressure may be equalized in the machined shape. may become impossible.

An object of the present invention is to make the surface temperature distribution of the roller uniform and to make it possible to change the shape of the roll according to the amount of deflection of the roll.

This invention makes it possible to partially control the amount of heat generated along the axial direction of the roll, change the outer circumferential shape of the roll based on the difference in thermal expansion based on the controlled amount of heat generated, and make it possible to change the shape of the outer periphery of the roll. A feature is that the roll surface temperature distribution is made uniform by installing a hollow chamber in which a gas-liquid two-phase heating medium is sealed in the thick part.

In this invention, an induction heating mechanism is particularly used as a heating mechanism for this purpose. As is already known, this type of mechanism is mainly composed of an iron core (for example, a wound iron core) and an electromagnetic wire ring wrapped around the outer periphery of the iron core, and is used by installing this inside a rotating roller. . When the electromagnetic wire is energized by an alternating current power source, the resulting alternating magnetic flux induces a short-circuit current in the circumferential direction on the circumferential side wall of the rotating roller, causing the roller itself to generate heat by Joule heat.

The electromagnetic coil is the primary coil of the transformer, and the roller is the secondary short-circuit coil, and the voltage distribution based on the electromagnetic coupling formed between them, and therefore the heat generation distribution, are as follows:
It can be inferred that the parabolic distribution is strongest in the center along the axial direction of the electromagnetic wire ring. In this invention, in order to actively change this distribution state and control the difference in heat generation temperature, the ampere turn of each part of the electromagnetic wire ring along the axial direction of the roller can be freely controlled.

Embodiments of the present invention will be described with reference to FIG. 3 and subsequent figures. In FIG. 3, 1 is a roller made of magnetic material, both ends of which are connected to flanges 4 and 5 connected to rotating shafts 2 and 3, and when one of the rotating shafts is rotated by a rotational drive source, The roller 1 is adapted to rotate. A plurality of jacket chambers 6 are formed in the thick part of the peripheral wall of the roller 1, and a plurality of jacket chambers are arranged in parallel along the circumferential direction of the roller 1 so as to be independent from each other or communicate with each other at the ends. A gas-liquid two-phase heat medium is sealed inside.

The heat medium is evaporated by the heat generated by the roller 1,
When this comes into contact with a low-temperature part of the roller 1 (the inner wall surface of the jacket on the front side of the roller 1), it condenses and generates latent heat. This latent heat heats the lower temperature area. As a result, roller 1
surface temperature becomes uniform. The condensed heat medium evaporates when it comes into contact with a high-temperature part of the roller 1 (the inside wall surface of the jacket on the inner surface of the roller 1). Repeat this below.

Although there is a tendency for the temperature of the outer peripheral wall surface to be equalized and the temperature of the inner peripheral wall surface to be equalized at the same time due to the equalizing action of the heating medium, the heat flux of the heat generation is directed outward in the radial direction within the wall thickness of the roller. Even if the heat generation distribution curve is flattened to some extent, the temperature is not uniform to the extent that it becomes a uniform distribution.

7 is a fixed shaft passing through the rotating shafts 2 and 3; 8 is a magnetic flux generating mechanism supported by the shaft 7 and placed inside the roller 1; an iron core (for example, a wound core) 9 supported by the shaft 7; A plurality of electromagnetic wire rings 1 wound around 9
It is composed of 0, 11, and 12. Here, the central electromagnetic wire ring 10 is wound near both ends thereof so as to overlap the ends of the electromagnetic wire rings 11 and 12 on both sides. The ampere turns of each electromagnetic wire ring can be controlled independently of each other. As a specific example, the energizing current of each electromagnetic wire ring can be adjusted by, for example, a saturable reactor.

FIG. 4 shows a circuit diagram for this purpose.
Here, each electromagnetic wire is energized using a three-phase power supply, that is, electromagnetic wires 11 and 1 are provided between the U-V phase, between the V-W phase, and between the W-U phase.
0,12, saturable reactor 13,14,15
Connect via.

In this configuration, the surface temperature of the roller 1 is kept uniform, the amount of heat generated at the center of the roller 1 is made larger than the amount of heat generated at the ends, and the diameter of the center of the roller 1 is made larger than that of the ends due to the difference in thermal expansion. For this purpose, as shown in FIG. 3, a temperature sensor 16 for detecting the surface temperature of the roller 1 and a temperature sensor for detecting the temperature at the center and end portions of the inner surface of the roller 1 are installed. Install vessels 17 and 18. When each detected value of each temperature sensor 16 to 18 is θ _S , θ _H , θ _L , the detected value θ _S is constant and the difference between the detected values θ _H and θ _L is the desired amount of deflection. It is sufficient if the control is performed so that the value is determined from .

Therefore, as shown in Fig. 4, the detected value θ _S is compared with a set reference value according to the roller surface temperature to be maintained by the comparator 21, and the output is adjusted so that both values remain constant. Saturation reactor 1
3 and 15 control windings 13a and 15a,
The energizing current of the electromagnetic wire rings 11 and 12 is controlled. Furthermore, the difference between the detected values θ _H and θ _L is calculated by a subtracter 22 . The output is compared by the comparator 23 with a set reference value determined by the temperature difference according to the amount of deflection (crown amount) to be maintained, and the comparison output is used to adjust the saturable reactor 14 so that both values are constant. The control winding 14a is controlled to control the energizing current of the electromagnetic coil 10.

By energizing each electromagnetic wire, magnetic flux is induced in each portion of the roller 1 facing each electromagnetic wire. Each magnetic flux is maximum at a portion facing the center along the axial direction of each electromagnetic wire ring, and decreases toward the end. In other words, as shown in FIG. 5, when the horizontal axis is the distance in the axial direction of the roller 1, the magnetic fluxes generated by the electromagnetic wire rings 10, 11, and 12 are expressed as φ ₁ , φ ₂ , and φ ₃ , respectively. The distribution is as follows.
Since the voltage induced in the part of the roller 1 facing each electromagnetic wire ring is proportional to the amount of magnetic flux interlinked with the roller part, the voltage induced in the part where the electromagnetic wire wheels overlap and the part facing each other is also vectorial. The value is the composite value. However, the polarity of the central electromagnetic wire ring 10 is reversed.

As a result of the above, each of the magnetic fluxes φ ₁ to _{φ 3} is combined to form a chevron-shaped or arc-shaped distribution state with the maximum at the center. Therefore, the distribution of heat generation based on the magnetic flux due to such distribution also becomes mountain-shaped or arc-shaped.
There is a difference in heat generation between the central part and the end part of the roller 1, and the roller 1 has a chevron-shaped or arc-shaped shape along its axial direction.
In other words, it becomes deformed like a crown roller as shown in FIG. However, the thermal expansion in the outer diameter direction of the roller is caused by the average temperature in the radial direction of the roller wall thickness. The temperature distribution on the inner circumferential wall surface of the roller does not directly reflect the amount of crown. Needless to say, the degree of this deformation depends on the difference between the detected values θ _H and θ _L , and therefore, the set reference value of the comparator 23 may be changed as appropriate.

For example, if the energizing current of the electromagnetic wire ring 10 is increased, the magnetic flux φ ₁ in FIG. 4 becomes the magnetic flux φ' ₁ as shown by the dotted line. Therefore, the composite magnetic flux also becomes φ' ₀ , so the amount of crown of the roller 1 becomes larger than before.

Note that the temperature difference between the detected values θ _L and θ _H is a value at the inner surface of the peripheral wall of the roller 1 . Needless to say, the temperature of the surface of the roller 1 is equalized by condensation and vaporization of the heat medium in the jacket chamber 6.

FIG. 6 shows an embodiment in which the electromagnetic wire is energized using a single-phase power supply. In this case, an electromagnetic wire ring 10 is installed in the center, and an electromagnetic wire ring 11 is installed over almost the entire length of the roller 1 in the axial direction, and both electromagnetic wire wheels 10, 1
1 are connected in parallel between the lines of a single-phase electric wire via saturable reactors 14 and 13. FIG. 7 shows the magnetic flux distribution in this case, where the magnetic flux due to the electromagnetic wire 10 is φ ₁ , the magnetic flux due to the electromagnetic wire 11 is φ ₂ , and the composite magnetic flux of both magnetic fluxes is φ ₀ . As understood from the composite magnetic flux φ ₀ , this has a mountain or arc shape, and therefore the heat generation distribution of the roller 1 has almost the same shape. It is possible that the peripheral wall of the roller 1 is deformed into a mountain or arc shape due to the difference in heat generation distribution between the central portion and the end portion of the roller 1, and that the extent of the deformation depends on an increase or decrease in the energizing current of the electromagnetic coil 10. This is the same as in FIGS. 4 and 5.

In the above explanation, the ampere turn is adjusted by changing the current flowing through the electromagnetic wire.
Alternatively, the ampere turns may be adjusted by changing the voltage applied to the electromagnetic wire or by changing the number of turns.

As detailed above, according to the present invention, the non-uniformity of the nip pressure due to deflection due to the load on the roller can be solved by changing the outer peripheral shape due to the difference in thermal expansion, without requiring crowning of the roller. Therefore, it is possible to eliminate the complexity of roller machining, and it is also possible to make corrections according to the amount of deflection of the roller.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of the use of the roller device, Fig. 2 is a front view of a conventional example, Fig. 3 is a front view showing an embodiment of the present invention, with the upper half sectioned. 5 is a circuit diagram, FIG. 5 is a magnetic flux distribution curve diagram, FIG. 6 is a circuit diagram of another embodiment of the present invention, and FIG. 7 is a magnetic flux distribution curve diagram. 1... Roller, 2, 3... Rotating shaft, 6... Jacket chamber, 8... Magnetic flux generation mechanism, 9... Iron core, 1
0-12...Electromagnetic wire ring, 13-15...Saturable reactor.

Claims (1)

[Claims] 1. A jacket chamber containing a gas-liquid two-phase heat medium is provided in the peripheral wall of the rotating roller, and a magnetic flux generating mechanism consisting of an iron core and an electromagnetic wire ring is installed inside the roller, and the axial direction of the roller is An induction heating roller device in which the ampere turn of the electromagnetic wire ring can be locally controlled so that the internal circumferential surface along the radial axis has a partially different calorific value from other parts to generate a difference in thermal expansion.