JPH09260050A - Induction heating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the temperature control of roller surface by applying to an induction heating coil a magnetic guide member guiding flux generated by the induction heating coil to a secondary conductor. SOLUTION: A magnetic guide 15' is structured to have a plurality of convex magnetic poles extending radially outwardly to provide uniform temperature on the roller surface. A direct current coil is provided radially inside the convex pole, to detect jule loss generated by the convex pole by a temperature sensor mounted on the roller surface to instruct direct current control instructions from a controller to a plurality of coils located axially at both ends to control the direct current to provide homogenous temperature at the roller surface. The entire coil comprising the direct current coils located axially at both ends and the alternative current coil therebetween is instructed by the controller with alternative current instructions, a plurality of coils located axially at both ends are provided with control instructions for both direct and alternative current, the interposed coil is provided only with the alternative current instructions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating roller used in a direct drawing method for synthetic fibers, particularly at high temperature.
The present invention relates to an induction heating roller suitable for high speed.

[0002]

2. Description of the Related Art FIG. 10 shows a synthetic fiber described as prior art prior to the application in Japanese Patent Application No. 57-19516 (Japanese Utility Model Application Laid-Open No. 58-122393), which is a prior invention of the applicant. It is a sectional side view which shows the induction heating roller used for direct drawing (prior art 1). The schematic structure of this induction heating roller will be described below. The rotating roller (induction heating roller) 1 is formed in a double hollow cylinder with a bottom, and a coil 8 is inserted into this hollow portion coaxially with the shaft center (rotating shaft) 2 so that the rotating roller 1 A secondary conductor (conductive ring) 9 made of a highly conductive material is formed along the circumference. A coil 8 is wound around the hollow portion of the rotary roller 1, and locking members 6a and 6b of the coil 8 are formed at both ends of the bobbin (iron core) 6 in the axial direction. The stop member 6 a has the same outer diameter as the outer diameter of the rotating roller 1 and is arranged outside the rotating roller 1 in the axial direction. When an alternating current is passed through the coil 8, an alternating magnetic flux Φ ₀ is generated in the bobbin 6 and the rotating roller 1, and the secondary conductor 9
11, an eddy current io flows in a direction to cancel this magnetic flux Φ ₀ and the secondary conductor 9 generates heat, and the heat is transferred to the outer peripheral surface of the rotating roller 1 and heated to a predetermined temperature. It On the other hand, leakage flux Φe is generated at both ends of the coil 8,
At both ends of the secondary conductor 9, an eddy current ie flows in a direction opposite to the eddy current io in a direction of canceling the leakage magnetic flux Φe. Therefore, the current density of the eddy current io in the secondary conductor 9 is 12, the temperature of the outer peripheral surface of the rotating roller 1 also decreases at both ends as compared with the central portion as shown in FIG. 12, and further heat reduction due to heat dissipation at both ends is added to the rotating roller 1. The temperature of the outer peripheral surface is not uniform, and the thickness of the heated object such as chemical fiber cannot be made constant.

Japanese Patent Application No. 57-19516 (Japanese Utility Model Application Laid-Open No. 58-122393) is an improvement of the prior art 1 in that the surface temperature of the rotating roller is not uniform, as shown in FIG. A magnetic conducting member 15 for guiding the magnetic flux generated from the coil 8 to the secondary conductor 9 is added to both ends of the coil 8 in the axial direction. In FIGS. 13 and 14, members other than the magnetic conducting member 15 are the same as those of the conventional rotary roller 1 described above, and therefore, the same or similar reference numerals are used and duplicate description is omitted. Locking members 6d and 6c at both axial ends of the bobbin (iron core) 6 are formed integrally with the bobbin 6, and a pair of left and right conductive members formed of a material having a high magnetic permeability in a ring shape are formed on outer peripheral portions thereof in the radial direction. The magnetic members 15, 15 are locking members 6d,
6c is coaxially joined. In this configuration, in FIGS. 13 and 14, the magnetic flux Φ ₀ is generated in the path indicated by the solid arrow to generate the eddy current io, and the magnetic flux Φd indicated by the alternate long and short dash line is generated at both axial ends of the rotating roller 1. Referring to part C in FIG. 14, when the rotary roller 1 rotates in the direction of arrow F, both ends of the secondary conductor 9 cut the magnetic flux Φd, and an electromotive force corresponding to the rotation speed of the rotary roller 1 is generated in this part. ,
Due to this electromotive force, the paths D and E are provided to both ends of the secondary conductor 9.
The eddy current id shown in Fig. 12 flows and both ends of the secondary conductor 9 in the axial direction generate heat. This heat is transmitted to both ends of the outer periphery of the rotating roller 1 and the temperature rises. Is raised so as to approach parallel to the axis Z as indicated by the arrow.

Japanese Examined Patent Publication No. 52-14856 (Prior Art 2)
The problem is that the surface temperature of the rotating roller is low at both ends in the axial direction and is non-uniform, which is solved by a mechanical means of providing a jacket chamber. Japanese Patent Application No. 57-19516 (Japanese Utility Model Application Laid-Open No. 58-122393), which is the prior application of the present invention.
Are locking members 6d, 6 at both axial ends of the bobbin (iron core) 6.
This is in contrast to the case where the magnetic conducting member 15 is arranged on the outer side in the radial direction of c and the problem is solved by an electromagnetic means, but the description with the drawings is omitted. In the publication of this prior art 2,
An alternating magnetic flux generating mechanism is provided inside a rotating roller made of a magnetic material, and a thick tube (secondary conductor) having high conductivity (heat and electricity) is closely attached to the inner wall surface of the roller to insert the thick tube ( A jacket chamber consisting of a large number of through holes in which a heat medium is enclosed along the cylinder axis is provided inside the secondary conductor, and the heat medium enclosed inside this jacket chamber keeps the surface temperature of the rotating roller uniform. In addition, a protective cylinder for protecting the jacket chamber is closely attached to the inner wall surface of the jacket chamber.

Japanese Patent Publication No. 62-62431 (Prior Art 3)
Relates to a high temperature roller by induction heating for use for the same purpose of direct drawing of synthetic fiber, in which the radial outer peripheral surface of the induction magnetic flux generating mechanism is covered with a heat insulating layer, while the temperature detecting end is in the heat insulating layer or It is provided between the heat insulating layer and the induction magnetic flux generating mechanism, and the inner peripheral surface of the roller body and the temperature sensing portion at the temperature detecting end are blackened to facilitate detection of the temperature of the roller body. Further, in the claims and the embodiments of the prior art, the magnetic flux generating mechanism is divided into a plurality of sections, and the temperature detecting end is provided for each divided section, and each section is independent. It discloses a high temperature roller in which the temperature is controlled. The description of the related art 3 will also be omitted with reference to the drawings.

Japanese Patent Publication No. 62-8912 (Prior Art 4) discloses
The present invention relates to a rotary roller by induction heating for use for the same purpose, and includes an annular layered iron core leg of an induction magnetic flux generating mechanism inside the rotary roller, and a position where the iron core leg is divided into three equal parts,
It consists of annular yokes provided at both ends and windings wound on the iron core legs between the yokes, and these windings overlap each other at the adjacent portions, so that the magnetic flux generated by the windings. By superimposing and increasing the induced voltage in this portion, the surface temperature distribution of the rotating roller is averaged. The description of the related art 4 will be omitted with reference to the drawings.

[0007]

In the direct drawing system for synthetic fibers, a high winding speed is required, which causes many difficult technical problems. In the synthetic fiber drawing system, the undrawn system from the spinning cylinder is guided to the first stage and the subsequent rotary heating roller, and a large heat load is applied to the roller, which adversely affects the temperature distribution of the roller. Therefore, it has serious consequences that affect the yarn quality. Therefore, in each of the above-mentioned related arts, a structure for equalizing the roller surface temperature was also adopted, but the temperature is easily reduced structurally at both ends of the roller, and this temperature decrease cannot be compensated, so the temperature is equalized. Was not perfect.
The temperature control with respect to the variation of the load due to the state of the fiber which the induction heating roller contacts could not be adequately dealt with even by providing the magnetic conducting member or the like according to the applicant's prior application. From this point of view, it is an object of the present invention to apply a magnetic conducting member that guides the magnetic flux generated from the induction heating coil to the secondary conductor to the induction heating coil to accurately control the temperature of the roller surface.

[0008]

[Means for Solving the Problems]

1) The magnetic conducting member has a structure having a plurality of convex magnetic poles protruding outward in the radial direction to make the temperature of the roller surface uniform by Joule heat generated by the rotation of the roller, 2) Furthermore, convex A DC coil is provided radially inward of the magnetic pole, and the Joule loss generated by the convex magnetic pole is detected by the temperature sensor installed on the roller surface. A uniform temperature of the roller surface is controlled by applying a direct current. 3) An AC control command is given from the control device to the entire coil including the DC coils at both axial ends and the intermediate AC coil,
The problem has been solved by providing control commands of direct current and alternating current from the control device to the plurality of coils at both ends in the axial direction, and by providing only alternating current control commands to the intermediate coil.

[0009]

1 is a side sectional view showing a first embodiment of the present invention, and FIG. 2 is a front sectional view taken along the line AA of FIG. The first embodiment of the present invention will be described with reference to FIG. An annular secondary conductor 9 is arranged in close contact with the inner circumference of the induction heating roller 1, and locking members 6 integrally formed at both axial ends of the iron core 6 of the induction heating roller 1.
At the tips protruding outward in the radial direction of d and 6c,
As shown in FIG. 2, a first magnetic conducting member 15 'having a plurality of convex magnetic poles 15a spaced in the circumferential direction is arranged. Only the coil 8 is wound around the iron core 6. By providing the first magnetic conducting member 15 'having the plurality of convex magnetic poles (hereinafter, also referred to as convex poles) 15a, the Joule heat generated by the rotation of the roller achieves the uniformization of the roller temperature to some extent. To be done.

FIG. 3 is a side sectional view showing the second embodiment, and the first magnetic conducting member 15 'of the first embodiment.
In addition to the above, the locking members 6 at both axial ends of the iron core (bobbin) 6
A direct current magnetic flux generating coil (hereinafter, referred to as "inward" in the radial direction inward of the first magnetic conducting member 15 'in each inward axial direction of d and 6c).
DC coils 52 and 53 are provided, and these DC coils 52 and 53 are wound with an intermediate AC magnetic flux generating coil (hereinafter abbreviated as AC coil) 51 interposed therebetween.
The magnetic flux generated by the DC coil 52 is the DC coil 53 on the side opposite to the axial direction (left in the figure) on the side of the first magnetic conducting member 15 '.
If the magnetic circuit is symmetrical with respect to both ends, it is impossible to individually control the Joule heat at each end by the DC coils 52 and 53. However, in the structure shown in FIG. 3, between the axially outer end surface 6 ″ of the locking member 6c on the right side in the drawing of the iron core 6 and the inner surface of the bottom wall 1 ″ of the induction heating roller 1 of the double hollow tubular body. Since there is a gap g in the DC coil 52 and the DC coil 52 and 5
3 can be individually controlled using the temperature sensors S ₁ , S ₂ , S ₃ .

The independence of DC control is improved by increasing the leakage of DC flux Φl ₁ in the magnetic circuit formed by the DC coils 52 and 53, since the magnetic circuits at both ends in the axial direction are asymmetric. Therefore, FIG. 4 showing the third embodiment.
Then, the locking members 6d at both axial ends of the iron core 6 of FIG.
Instead of 6c, as shown in FIG. 4, the second magnetic conducting member 15d,
15c is arranged, and these second magnetic conducting members 15d, 15
The third magnetic conducting members 15f and 15e are arranged in the straight part 6'parallel to the rotation axis 2 of the iron core 6 inside each c. Thus, the second magnetic conducting member 15d and the third magnetic conducting member 15f surround the DC coil 53 at the left end in the axial direction. Similarly, on the right side, the second magnetic conducting member 15c and the third magnetic conducting member 15f are surrounded. The member 15e surrounds the DC coil 52 at the right end in the axial direction. As a result, the magnetic circuit for the DC magnetic flux generated by the DC coils 52 and 53 is formed into a convex pole shape that positively increases the leakage Φl _{1 of the} DC magnetic flux, so that the control of the DC coils 52 and 53 is independent. Improved.

FIG. 5 is a side sectional view showing a fourth embodiment, in which the magnetic flux generated by each coil independently forms a magnetic circuit. In FIG.
A fourth magnetic conducting member 15j having an inverted L-shaped cross section is provided from a position 6e which is kept inward from the locking member 6d at the axially left end of the iron core 6 by a predetermined distance. Similarly, a predetermined distance is maintained inward from the locking member 6c at the right end of the iron core 6 in the axial direction.
The fourth magnetic conducting member 15k having an inverted L-shaped cross section from the position of f
Is provided. One leg 15m of the fourth magnetic conducting member 15j extends outward in the radial direction perpendicularly to the parallel portion 6'of the iron core 6, and the other leg 15n is perpendicular to the leg 15m in parallel with the axis and in the secondary direction. The conductor 9 extends axially outward in parallel to the inner circumference of the conductor 9 to the front of the locking member 6d. One leg 15p of the fourth magnetically conductive member 15k at the right end in the axial direction is a parallel portion 6'of the iron core 6.
And the other leg 15q extends axially outward to the front of the locking member 6c in parallel with the axis and integrally with the leg 15q. ing. The locking member 6d, the parallel portion 6'of the iron core 6, and the left L in the axial direction
A DC coil 53 is wound inside the character-shaped fourth magnetic conducting member 15j, and similarly, a locking member 6 is provided at the right end in the axial direction.
c, the parallel portion 6'of the iron core 6, and the L-shaped fourth magnetic conducting member 1
A DC coil 52 is wound inside the area surrounded by 5k.

The fifth embodiment of the present invention is based on the above first embodiment.
According to the fourth embodiment, a DC coil at both ends in the axial direction and an AC coil in the middle are used together, and the controller controls the current supply to each coil. As an example, in order to use the DC coils 52 and 53 at both ends in the axial direction of FIG. 3 shown as the second embodiment and the AC coil 51 in the middle together to make it possible to supply an AC current to the DC coils 52 and 53, As shown in FIG. 6, the control device 20 is connected to form a control circuit. In FIG. 6, 20b and 20c are adjustable DC power supplies that apply DC voltage to the DC coils 52 and 53, respectively, and 20a is each coil 53, 5
It is an adjustable AC power supply that applies an AC voltage to 1, 52. The respective voltages of the DC power supplies 20b and 20c are controlled by DC control commands α ₂ and α ₁ issued by the control device 20 based on the detection signals from the temperature sensors 21a, 21b and 21c, respectively, while the AC power supply 20a is controlled. The output voltage of is output from the control device 20 based on the detection signals from the temperature sensors 21a, 21b, and 21c, and is controlled by the AC control command β ₁ . As a result, receiving the detected temperature signals from the temperature sensors 21a, 21b, 21c,
A controlled amount of alternating current is supplied to the DC coils 52 and 53 at both ends to increase Joule heat corresponding to A and B in FIG. 9 and improve nonuniformity of the roller surface temperature distribution. The control method shown in FIG. 6 can be similarly applied to the second to fourth embodiments.

Operation: In FIG. 2, a plurality of convex magnetic poles 15
The magnetic flux Φd′a passes through each of a. FIG. 7 shows FIG.
7A shows a change in magnetic flux at a point P of the secondary conductor 9 shown in FIG. 7, FIG. 7A shows a change in magnetic flux with time, FIG. 7B shows a change in magnetic flux with a rotation angle θ, and FIG. (C)
Indicates a rectified waveform. FIG. 8 shows the main magnetic flux Φ ₀ a, the side magnetic flux Φ sa, and the first magnetic flux Φ sa in the induction heating roller 1 having the structure shown in FIG.
FIG. 6 is a partial side view showing the relationship of the magnetic flux Φd′a passing through the magnetic conducting member 15 ′ of FIG. The symbol a indicates an AC magnetic flux. Φ ₀ a = Φd′a + Φsa ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (1) Φd′a ＝ Φp ＋ Φpa ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2) Φ ₀ a, Φd′a and Φsa are alternating magnetic fluxes generated by the AC coil 51 of FIG. 3, and Φp and Φpa are respectively
They are the direct current component and the alternating current component of the magnetic flux passing through the first magnetic conducting member 15 '. From (1) and (2), Φ ₀ a = Φp + Φpa + Φsa (3) Therefore, the induced voltage Vo generated by the alternating magnetic flux is Vo = −dΦ ₀ / dt = −ω ₀ (Φpa + Φsa) (4) where ω ₀ = 2πf ₀ f ₀ is the power supply frequency. Also, dΦpa / dt = 0. As shown in FIG. 8, .PHI.d'a occurs on the circumference of the convex electrode (end portion of the steel ring), so that when the roller rotates at the rotation speed N, the following voltage Ve is induced. Ve = −nωe (Φpa + Φp) where ωe = 2πN n is the number of convex poles of the convex pole 15a of the first magnetic conducting member 15 ′. FIG. 9 is a graph showing the Joule heat io generated by the induced current due to each of the above actions and the temperature distribution T on the roller surface. In the figure, the broken line (a), the two-dot chain line (b) and the one-dot chain line (c) are the Joule loss io of the roller surface, respectively.
The solid lines a, b and c show the temperature distribution T on the roller surface.
The broken line (a) is based on ωe (Φpa + Φ ₀ ), the two-dot chain line (b) is nωeΦpa added thereto, and the one-dot chain line (c) is nωeΦp added thereto. Of these, nωeΦp is the temperature sensor 20a, 20b, 20c
It is possible to make the surface temperature uniform by detecting it by controlling the DC winding.

[0015]

According to the induction heating roller of the present invention, the salient pole members, which are circumferentially spaced, are arranged at both axial ends of the secondary conductor.
In addition, the induction heating coil is entirely AC only, or both ends in the axial direction are DC coils and the middle is an AC coil to control only the DC coils at both ends. Since the coil is configured so that both orthogonal control commands are given, it has the following excellent effects. (1) The Joule heat significantly improved the uniformity of the roller surface temperature. That is, as shown in FIG. 9, regarding the homogenization of the roller surface temperature, the curve (a) (amount A) showing the generated Joule heat component, which was insufficient in the conventional technique, is represented by nωeΦpa
Is shown in curve (b) by adding (amount A + B)
Up to (amount A + B + C) shown by the curve (c) can be improved by adding nωeΦp. (2) In this case, in addition to the AC coil, DC coils are arranged at both ends, and the current of the DC coil is controlled by the detection result of the temperature sensor of the roller surface temperature.
The accuracy of homogenizing the surface temperature of the device can be further improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a front sectional view taken along the line AA of FIG.

FIG. 3 is a side sectional view showing a second embodiment of the present invention.

FIG. 4 is a side sectional view showing a third embodiment of the present invention.

FIG. 5 is a side sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a control circuit diagram showing a control method.

7A and 7B collectively show a state of magnetic flux, FIG. 7A shows a change with time, FIG. 7B shows a change with a rotation angle, and FIG. 7C shows a rectified waveform.

FIG. 8 is a partial side view showing the relationship of magnetic flux in the induction heating roller shown in FIG.

FIG. 9 is a graph showing the Joule heat generated by an induced current due to each action and the temperature distribution on the roller surface.

FIG. 10 is a side sectional view showing an induction heating roller according to the prior art.

11 is a schematic diagram showing the generation of magnetic flux in FIG.

12 is a graph showing eddy current generation and temperature change in FIG. 11. FIG.

FIG. 13 is a side sectional view of an induction heating roller improved in the related art by providing a magnetic conducting member.

FIG. 14 is a schematic diagram showing the generation of magnetic flux in FIG.

[Explanation of symbols]

1: Induction heating roller 1 ": Bottom wall of induction heating roller 2: Rotating shaft 5: Rotating shaft mounting part 6: Iron core 6 ': Parallel part of iron core 6": Outer end surface of iron core 6d, 6c: Locking member 8: Coil 8A: AC magnetic flux generating mechanism 9: Secondary conductor 15 ': First magnetic conducting member 15a: Convex magnetic poles 15d, 15c: Second magnetic conducting member 15f, 15e: Third magnetic conducting member 15j, 15k: the fourth conductive magnetic member 15,15n, 15p, 15q: leg 20a: AC power supply 20b, 20c: a DC power source 51: AC coils 52 and 53: DC coils _{S 1, S 2, S 3} : temperature sensor g: gap Φl ₁ : Leakage of DC magnetic flux

Claims (5)

[Claims] 1. A double-hollow cylindrical shape, one end of which in the axial direction is an opening, and both inner surfaces of the inner tubular body are in close contact with the rotary shaft (2) to form a rotary shaft mounting portion (5). , An induction heating roller (1) that rotates integrally with the rotating shaft (2), and the outer peripheral surface of the outer tubular body adjusts the thickness of the chemical fiber and the like.
An annular parallel portion (6 ') arranged parallel to the rotation axis (2) in a space between the outer tubular body and the inner tubular body of the induction heating roller (1), The locking member (6d, which rises outward in the radial direction from both axial ends of the portion (6 '),
An annular core (6) having 6c); this annular core (6)
AC magnetic flux which has a coil (8) wound coaxially with the induction heating roller (1) on the outer peripheral surface of the parallel portion (6 ') of the above, and is rotatable relative to the rotating shaft (2). A generating mechanism (8A); a secondary conductor (9) closely attached to the inner peripheral surface of the outer tubular body of the induction heating roller (1), and the locking member (6)
d, 6c) is disposed on the outer peripheral surface of the secondary conductor (9) with a predetermined gap, and guides the magnetic flux generated from the AC magnetic flux generating mechanism (8A) to the secondary conductor (9). In the induction heating roller (1) having members (15) and: In place of the annular magnetic conducting member (15), a predetermined distance is provided in the circumferential direction from the outer peripheral surface of the locking members (6d, 6c). A first magnetic conducting member (15 ') is provided which has a plurality of convex magnetic poles (15a) for keeping and protruding and for guiding the AC magnetic flux generated from the AC magnetic flux generating mechanism (8A) to the secondary conductor (9). An induction heating roller (1) characterized in that the roller temperature is made uniform by Joule heat generated by the rotation of the roller. 2. The induction heating roller (1) further comprises a plurality of DC coils (52, 53) arranged on the inner circumference of the first magnetic conducting member (15 ') at both axial ends, and these DC coils (52, 53). An AC coil (51) arranged in the middle of the DC coil (52, 53) in the axial direction; and an axial outer end surface (6 ″) of the locking member (6c) on the axial right side of the iron core (6), The gap (g) between the double hollow tube and the inner surface of the bottom wall (1 ″) of the induction heating roller (1) makes it asymmetrical, and the roller surface has a predetermined interval in the axial direction. A plurality of temperature sensors (S ₁ ,
S ₂ , S ₃ ), and Joule heat generated from the convex magnetic pole from the DC coil is detected by the temperature sensor (S ₁ , S ₂ , S ₃ ) installed on the roller surface, The induction heating roller (1) according to claim 1, characterized in that the roller surface temperature is made uniform by controlling the electric current to adjust the value of the Joule heat. 3. A second magnetic conducting member (15d, 15c) arranged in place of the locking member (6d, 6c) at both axial ends of the iron core (6); and these second magnetic conducting members (15d, 15c). 15
d, 15c) axially inward of each of them, a third magnetic conducting member (15f, 15e) arranged in a straight line portion (6 ') parallel to the rotation axis (2); The second magnetic conducting member (15d) and the third magnetic conducting member (15f)
Surrounds the DC coil (53) at the left end in the axial direction, and similarly surrounds the DC coil (52) at the right end in the axial direction by the second magnetic conducting member (15c) and the third magnetic conducting member (15e) on the right side. The DC coils (52, 5, 5)
3) Induction heating in which the independence of control of the DC coils (52, 53) is improved by making the magnetic circuit for the DC magnetic flux due to 3) and the convex pole shape that positively increases the leakage (Φl ₁ ) of the DC magnetic flux. Laura (1). 4. Legs (15m, 15p) standing up inwardly from the locking members (6d) at the left and right ends of the iron core (6) in the axial direction, perpendicularly to the rotating shaft (2) from a position keeping a predetermined distance.
And the locking members (6d, 6c) perpendicular to the legs (15m, 15p), parallel to the parallel part (6 ') of the iron core (6), and parallel to the inner circumference of the secondary conductor (9). ) Has legs (15n, 15q) extending axially outwardly,
Fourth magnetic conducting member (15j, 15k) having an inverted L-shaped cross section
And; in the interior surrounded by the locking members (6d, 6c) at both ends in the axial direction, the parallel portion (6 ') of the iron core, and the L-shaped fourth magnetic conducting members (15j, 15k) at both ends in the axial direction. The wound DC coil (53, 52); and the fourth magnetic conducting member (15)
j, 15k) AC heating coil (5
1) and; and the magnetic flux generated in each coil forms an independent magnetic circuit, respectively. 5. A DC power source for both terminals of a DC coil (52, 53) at one end and the other end in the axial direction of the induction heating roller (1) having the magnetic circuit according to any one of claims 2 to 4. (20b, 20c) are connected, AC power supply (2
0a) is connected between the outer terminals of both DC coils at both ends in the axial direction, and these DC coils (52, 53) are controlled by respective control units, and further, the DC coils (52, 53) at both ends in the axial direction are connected. ), The Joule heat corresponding to the alternating current is increased at both ends in the axial direction, and the temperature distribution on the roller surface is made uniform.