JPH0160911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an induction heating device for the surface of a roll used in a paper manufacturing process.

[Conventional technology]

In the paper manufacturing process, caliper (paper thickness) and hardness (hardness) greatly affect the main quality characteristics of paper, such as tactile, visual, and chemical properties, so their control is of great importance. Calipers and hardness in the width direction of paper sheets are uneven on the micron scale due to variations in factors such as paper basis weight, moisture content, and temperature. The nip pressure of the calendar stack is changed partially to compensate for unevenness.

The method of changing the roll diameter used to be by blowing cold air onto the roll surface to cool it, but in recent years, devices that use induction heating, which has excellent response speed, have come into use. Ta. FIG. 5 is a schematic diagram of a calendar stack. The paper 3 is wound around a roll, flows in the direction of the arrow, and is wound up. A plurality of heating coils 2 are arranged in a row in the width direction of the bottom roll 1 at the lowest stage and are attached to the outer peripheral surface of the roll 1 with a slight gap. The closer the heating coil 2 is to the roll surface, the greater the power induced in the roll and the higher the temperature rise value, but when the roll 1 is brought into contact with it,
Since the heating coil 2 may be damaged and the rolls may be scratched, causing serious defects in papermaking, a gap of about 2 to 3 mm is usually provided. The width of the 21 heating coils should be as narrow as possible in order to more precisely correct the unevenness of the paper 3, but due to manufacturing constraints of the heating coil 2 and the range where unevenness occurs, a width of about 100 mm is appropriate, and it is usually effective for rolls. Approximately 20 units will be installed with a width of 2 meters.

FIG. 6 shows a conventional roll surface induction heating device. In the figure, 1 is a roll, 2 is a plurality of heating coils arranged in the axial direction at a predetermined distance from the outer peripheral surface of the roll 1, 4 is a coaxial cable each having one end connected to the heating coil 2, and 5 is a coaxial cable. A high frequency generator is connected to the other end of each coaxial cable 4, 6 is a power supply panel, 7 is a power cable connecting the high frequency generator 5 and the power supply panel 6, and the power supply panel 6 is connected to a power supply (not shown). Connected.

Next, the operation will be explained. A power supply panel 6 receives a commercial frequency power supply, and a high frequency generator 5 for heating the rolls.
is supplied as the specified power source. Therefore, although not shown, depending on the receiving voltage, if a transformer is built in or a plurality of high frequency generators 5 are used, a branch no-fuse breaker or the like may be required. In order to shorten the heating time and cooling time of the roll 1 and improve responsiveness, a high frequency power source is used in which the current penetration depth induced in the roll 1 is small and the heat generating portion is concentrated in the surface layer. Commercial frequency alternating current power supplied through the power cable 6 is converted into high frequency power by the high frequency generator 5, and the power is supplied to the heating coil 2 via the coaxial cable 4.
When the load is an inductive load, this high frequency generator 5
Thyristors are used on both the forward and reverse conversion sides to generate high frequency power. For this reason, the high frequency generator 5
The shape is larger and compared to heating coil 2,
Because it was much larger, it had to be placed separately. Since the power up to the heating coil 2 is high-frequency power, it was connected using a coaxial cable 4 in order to reduce cable loss and to reduce the occurrence of surrounding metal loss.

[Problem that the invention seeks to solve]

Since the conventional induction heating device for the roll surface is constructed as described above, there are problems in that the high frequency generator is large and the number of wirings is large.

This invention was made to solve the above-mentioned problems, and is intended to reduce the size of the induction heating device.

[Means for solving problems]

The roll surface induction heating device according to the present invention includes:
A heating coil is formed by molding a conductor wound with a specified synthetic resin so as to face the surface of the roll at a specified distance, and a driving device for driving this heating coil is connected to a backing plate made of a magnetic material. It is connected to the heating coil via the heating coil.

[Effect]

The roll surface induction heating device according to the present invention can be made smaller and the number of wires can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, numerals 1, 6, and 8 are the same as the conventional one. Reference numeral 9 denotes a heating coil, and as shown in FIG. A pair of terminals 9c each connected to a wound conductor 9a is molded from a predetermined synthetic resin 9b so that the other end is substantially flat.
is provided so that it can be connected to the outside. Reference numeral 10 denotes a drive device that converts the supplied power into a predetermined frequency to drive the heating coil 9, and is configured as shown in the single line circuit diagram of FIG. In the figure, 10a
is a circuit breaker that opens and closes the power supply, 10b is a current transformer that detects current, 10c is an ammeter that displays the current detected by current transformer 10b, 10e is a reactor, 10f is a smoothing capacitor, 10g is an inverse conversion circuit, 10h is a parallel capacitor, 10i is an oscillation control circuit, and 10j is a photocoupler. In this way, each element forming the drive device 10 is attached to a predetermined container 1.
The container 10k has an output terminal 10 connected to each terminal 9c of the heating coil 9.
l, 10l and input terminal 1 connected to power supply panel 6
0m and a signal terminal 10n are provided.

As shown in FIG. 4, the heating coil 9 and the drive device 10 configured in this manner are mechanically connected by a predetermined attachment device 12 via a contact plate 11 made of a magnetic material. Thereby, each terminal 9c, 9c and 10l, 10l are electrically connected.

Next, the operation will be explained. In FIGS. 1 and 3, when commercial frequency power is supplied from the power cable 8 and the circuit breaker 10a is turned on, the supplied commercial power passes through the power circuit breaker 10a and the current transformation path 10b. The current is guided to the forward conversion circuit 10d, and the ammeter 10c displays the current value, that is, the input current. The voltage and current full-wave rectified by the forward conversion circuit 10d are converted into a substantially constant DC voltage with pulsating current smoothed by the rush current suppression reactor 10e and the smoothing capacitor 10f, and then converted to the inverse conversion circuit 10g.
guided by. In this state, external control signal terminal 10n
When a signal for operating the drive device 10 is inputted from the oscillation control circuit 10i, the oscillation control circuit 10i starts operating in an electrically insulated state by the photocoupler 10j. This oscillation control circuit 1
In order to give a conductive/non-conductive base drive signal to the transistor of the inverse conversion circuit 10g from 0i, current is supplied to the parallel capacitor 10h and the induction heating coil 9, and the parallel resonance frequency f of the parallel capacitor 10h and the heating coil 9 is increased. Oscillation starts at =1/2π√LC.

Incidentally, in synchronization with this oscillation state, at an appropriate timing, the transistor of the inverse conversion circuit 10g is turned on.
A voltage detection feedback circuit or the like is provided for non-conduction.

In the above embodiment, a case has been described in which the driving device 10 drives the heating coil 9 with high frequency. In this case, good results can be obtained if the wound conductor 9a is composed of a plurality of twisted conductors. Furthermore, the heating coil 9 is
This prevents the generated magnetic flux from shadowing the drive device 10.

In addition, in the induction heating device for the roll surface, the heating coil 9 and the drive device 10 have almost the same width in the longitudinal direction of the roll, and if this width is configured in the range of 80 to 130 mm, the roll surface will be heated by the calender roll of the paper making line. It is possible to control the temperature to a predetermined value.

Further, in the above embodiment, the case where the present invention is used in a paper manufacturing line has been described, but the same operation as in the above embodiment can be expected even when used in a metal foil production line.

〔Effect of the invention〕

As described above, according to the present invention, a heating coil is formed by molding a conductor wound with a predetermined synthetic resin so as to face the surface of a roll at a predetermined distance, and this heating coil is driven. Since the driving device is attached to the heating coil via the patch plate made of a magnetic material, the mounting space for the driving device can be reduced and the number of wiring lines can be reduced.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an induction heating device for a roll surface according to an embodiment of the present invention, Fig. 2 is a configuration diagram of a heating coil, Fig. 3 is a drive circuit diagram, Fig. 4 is an installation diagram, and Fig. 5 is the configuration diagram of the calendar roll stack,
FIG. 6 is a configuration diagram showing a conventional one. In the figure, 1 is a heated roll, 9 is a heating coil, and 10 is a drive device. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A heating coil molded of synthetic resin so as to face the surface of the heated roll at a predetermined distance; Induction heating of the surface of a roll, characterized in that a driving device whose width facing the longitudinal direction of the heated roll is almost the same as that of the heating coil is integrally attached via a contact plate made of a magnetic material. Device. 2. The roll surface induction heating device according to claim 1, wherein the heating coil is driven by high frequency power. 3. The roll surface induction heating device according to claim 1, wherein the width of the heating coil facing the longitudinal direction of the heated roll is in the range of 80 mm to 130 mm.