JP2015056224A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating apparatus of a novel system that allows for uniform and efficient heating treatment of the surface area of a large-sized metal plate material or block material by utilizing the magnetic flux passing on the outside of a solenoid coil skillfully, and by using a small and compact induction heating coil unit.SOLUTION: A flatwise coil peripheral surface of an induction heating coil unit 1 whose cross-sectional shape is a flat profile, constituted by inserting a magnetic core 12 of a magnetic material into a solenoid coil 11 formed by winding a coil conductor in a solenoid shape, is arranged to face the surface of a heated body 3 in parallel therewith. Subsequently, while applying an AC power to the solenoid coil 11, the coil unit 1 is mounted on a scanning drive unit, e.g., an industrial robot, and moved for scanning along the heating surface area of the heated body 3, thus induction heating a wide area thereof without uneven heating.

Description

  The present invention provides a metal plate material or a metal block material to be heated, for example, for heating and drying a painted surface of a switchboard casing or a car body surface, or for preheating a molding die such as aluminum. The present invention relates to an induction heating apparatus that performs induction heating.

  Nowadays, induction heating is widely used in various industrial fields, and as its application examples, induction heating is being studied for heating and drying the painted surfaces of automobile bodies and preheating molds such as aluminum. As this type of induction heating apparatus, those shown in Patent Document 1, Patent Document 2, and the like are known.

  On the other hand, as is well known, in the induction heating method, a heated object such as a metal plate is passed through the inside of a solenoid type induction heating coil in which a coil conductor is wound into a cylindrical shape, and an alternating generated in the induction heating coil. Solenoid coil system in which magnetic flux is induction-heated along the surface of the metal plate material, and alternating magnetic flux generated in the induction heating coil by placing an induction heating coil in which the coil conductor is wound spirally facing the surface of the heated object There is a transverse system that heats by acting in the thickness direction of the metal plate material.

  The above-described induction heating devices of Patent Documents 1 and 2 employ a transverse method using an induction heating coil in which a coil conductor is wound in a spiral shape.

JP 2011-69500 A JP 2010-284714 A

  By the way, the transverse induction heating apparatus disclosed in Patent Documents 1 and 2 have the following problems in terms of uniform heating.

  That is, an induction heating coil in which a coil conductor is wound in a spiral shape has a non-uniform magnetic field strength and magnetic flux distribution generated by the coil due to the influence of the coil shape, the winding pitch of the coil conductor, and the like. Therefore, the heating area of the object to be heated facing the induction heating coil has a donut shape, causing uneven heating in the heating surface area, and it is difficult to uniformly heat the surface of the object to be heated. . In addition, when the outer periphery side of the induction heating coil is applied to the edge portion of the heated body (plate material), the induction current induced in the heated body is concentrated and flows on the edge portion of the plate material, and this portion is locally overheated. There is also a problem.

  In order to deal with such a problem, in Patent Document 2 described above, a spiral induction heating coil is moved on the surface of the heated body to generate a blind spot (corresponding to the center of the heating coil) of the magnetic field acting on the heated body. However, even if this method is employed, the uneven heating temperature of the heated object cannot be eliminated.

  On the other hand, the solenoidal induction heating coil has a substantially uniform magnetic field strength and magnetic flux distribution inside the solenoidal coil, so that the problem of uneven heating does not occur like the spiral coil described above. In order to be applied to a heated body having a large structure such as a vehicle body, a huge solenoid coil surrounding the large heated body is required, which is not practical.

  The present invention has been made in view of the above points. By skillfully utilizing the magnetic flux passing outside the solenoid coil, the surface of a large area metal plate or metal block material using a small induction heating coil unit is provided. It is an object of the present invention to provide an induction heating apparatus that can heat a region uniformly and efficiently.

  In order to achieve the above object, according to the induction heating apparatus of the present invention, the induction heating coil has an induction heating coil in which a magnetic core is inserted inside a solenoid coil in which a coil conductor is wound in a cylindrical shape. A unit is formed, and the peripheral surface of the induction heating coil unit is arranged in parallel to the surface of the heated body, and in this state, the AC power is applied to the solenoid coil, and the coil unit is heated on the heating surface area of the heated body. It is assumed that the object to be heated is inductively heated by scanning along the line (Claim 1).

The induction heating coil unit can be specifically configured in the following manner.
(1) The induction heating coil unit is configured to have an elliptical shape or a flat shape such as a rectangular shape, and the flatwise surface of the induction heating coil unit is opposed to an object to be heated.
(2) Magnetic pole pieces for guiding the magnetic flux passing through the magnetic core intensively toward the heated body are provided at both ends of the magnetic core of the induction heating coil unit.
(3) In the preceding item (2), the magnetic pole piece has a flange shape that protrudes to the side of the coil turn adjacent to the coil end of the solenoid coil.
(4) The magnetic core and pole piece magnetic body provided in the induction heating coil unit is a ferrite sintered body or a laminated body of silicon steel sheets.
(5) For the solenoid coil wound around the outer periphery of the magnetic core of the induction heating coil unit, the winding pitch of the coil conductor at both ends of the coil is set densely, and the winding pitch of the coil conductor at the center of the coil is set roughly. (Claim 6).
(6) As the scanning moving means of the induction heating coil unit, the coil unit is mounted on a scanning drive device such as an industrial robot so as to scan and move the surface of the heated object.

According to the induction heating device of the present invention having such a configuration, the following effects can be obtained.
(1) Using a small solenoid coil unit that can easily handle scanning movements, it is possible to uniformly heat a large surface area of a heated object such as a plate or block having a large area without uneven heating. is there.

  That is, when the above-mentioned solenoidal induction heating coil unit is arranged opposite to the surface of the heated object and high frequency alternating power is supplied to the solenoid coil from an external power source, the coil unit is generated by the generated magnetic field (alternating magnetic field). Magnetic flux passing from the both ends to the outer peripheral side of the coil penetrates along the surface direction of the object to be heated. In this case, by inserting the magnetic core inside the solenoid coil, the magnetic flux density generated in the coil unit can be increased compared to the air-core coil, and most of the magnetic flux has a low magnetic resistance. Is followed by a closed loop path passing through the object to be heated in the plane direction.

As a result, an induced current (eddy current) is induced in the heated object due to the magnetic flux penetrating from the coil unit, and the induced current is concentrated and flows on the surface side of the heated object (the penetration depth of the induced current is an alternating power source). The surface area of the heated object facing the coil unit (substantially rectangular area through which the magnetic flux of the coil unit penetrates) due to the Joule heating of the induced current ) Is heated uniformly. The induction heating coil unit is mounted on a scanning drive device such as an industrial robot, and the moving area of the object to be heated is sequentially scanned and controlled to uniformly guide the wide area of the object to be heated. It becomes possible to heat.
(2) Here, the induction heating coil unit has an elliptical or rectangular flat cross-sectional shape, and the flat-wise outer peripheral surface of the induction heating coil unit faces the object to be heated. Corresponding to the peripheral surface (wide flat-wise surface), the area of the surface area in which the induced current is induced in the heated object is expanded, and even a heated object with a large area can be heat-treated with high work efficiency.
(3) Further, by providing magnetic pole pieces intensively guiding the alternating magnetic flux passing through the magnetic core toward the heated body at both ends of the induction heating coil unit, the heating efficiency of the heated body is increased. The magnetic pole piece can be increased, and the magnetic pole piece has a shape that protrudes from the magnetic core to the outer peripheral side of the coil close to the coil end of the solenoid coil, thereby generating leakage magnetic flux at the solenoid coil end, Further, it is possible to effectively reduce the transient temperature rise of the coil conductor and the coil loss (copper loss) by suppressing the bias of the current distribution at the coil end due to the interference of the leakage magnetic flux.
(4) For the magnetic core of the induction heating coil unit and the pole pieces arranged at both ends thereof, the magnetic body is made of a ferrite sintered body (soft ferrite) or a laminate of silicon steel plates, thereby reducing iron loss. It can be kept low.
(5) Furthermore, the magnetic field intensity generated in the solenoid coil in which the coil conductor is uniformly wound tends to decrease at both ends as compared with the coil central part. In this respect, in addition to the magnetic pole piece described above, Winding the coil conductor from the coil unit toward the object to be heated by winding the coil conductor at the both ends of the solenoid coil of the induction heating coil unit densely and winding the coil conductor at the center of the coil coarsely. The uniformity of the distribution of the magnetic flux in the axial direction of the coil can be improved, and the heated object can be efficiently and uniformly heated.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the structure of the induction heating apparatus by Example 1 of this invention, Comprising: (a) is a perspective view of the state which has arrange | positioned the to-be-heated body the induction heating coil unit whose cross-sectional shape is elliptical, (b) is a figure showing magnetic flux distribution corresponding to (a). It is a schematic block diagram which shows the structure of the induction heating apparatus by Example 2 of this invention using the induction heating coil unit which made the cross-sectional shape flat rectangular. It is a figure showing the scanning movement path | route of the induction heating coil unit at the time of carrying out the induction heating process of the whole surface area of a to-be-heated body. It is a figure showing the use condition which mounts an induction heating coil unit in an industrial robot, and carries out scanning movement to a to-be-heated body. It is explanatory drawing showing the penetration magnetic flux distribution of the to-be-heated body corresponding to the design model I of an induction heating coil unit, Comprising: (a) is arrangement | positioning sectional drawing of a coil unit and a to-be-heated body, (b) is a magnetic flux distribution figure. . It is explanatory drawing showing the penetration magnetic flux distribution of the to-be-heated body corresponding to the design model II of the induction heating coil unit which has arrange | positioned the pole piece to the both ends of a magnetic core, Comprising: (a) is arrangement | positioning sectional drawing of a coil unit and a to-be-heated body (B) is a magnetic flux distribution diagram. It is explanatory drawing showing the penetration magnetic flux distribution of the to-be-heated body corresponding to the design model III of the induction heating coil unit which arranged the magnetic pole piece adjacent to the both ends of a solenoid coil, Comprising: (a) is a coil unit and to-be-heated body (B) is a magnetic flux distribution diagram. FIG. 5 is a schematic cross-sectional view of an induction heating coil unit in which a solenoid coil is sparsely and closely wound as an application example.

  Embodiments of the induction heating apparatus according to the present invention will be described below based on the examples shown in FIGS.

  First, as Embodiment 1 of the present invention, the structure of an induction heating coil unit having an elliptical cross-sectional shape and a flat shape, and its induction heating function will be described with reference to FIG.

  In FIGS. 1A and 1B, 1 is a solenoid induction heating coil unit, 2 is a high-frequency power source, and 3 is an object to be heated (conductive metal plate material). Here, the solenoid induction heating coil unit 1 includes a flat solenoid coil 11 in which a coil conductor is wound in an elliptical shape, and a ferrite sintered body (soft ferrite) inserted into the solenoid coil 11 or a silicon steel plate. It is comprised from the magnetic core 12 used as the laminated body of this.

  And in order to induction-heat the surface area of the to-be-heated body 3 using this induction heating coil unit 1, arrange | position the flatwise surface of the coil unit 1 in parallel with the surface of the to-be-heated body 3 like illustration, The solenoid coil 11 is connected to the high frequency power source 2 and excited. As is well known, an alternating magnetic field is generated in the solenoid coil 11 to generate a magnetic flux φ. As shown in FIG. 1B, the magnetic flux φ forms a closed loop that passes through the magnetic core 12 and passes through the outer peripheral side of the solenoid coil 11. However, a part of the magnetic flux φ passes through the object to be heated 3 along the loop path. It penetrates in the surface direction.

  As a result, an induced current (eddy current) is induced in the heated body 3 and the induced current is concentrated along the surface side of the heated body (the penetration depth of the induced current is the frequency of the alternating power source, the heated body) The surface area of the object to be heated 3 that faces the flat-wise outer peripheral surface of the coil unit 1 by the Joule heating of this induced current (substantially rectangular surface through which the magnetic flux of the coil unit penetrates) Area) is heated uniformly. Then, if this induction heating coil unit 1 is scanned and moved along the surface of the body to be heated 3 in the direction of the arrow shown (direction perpendicular to the axial direction of the coil unit 1), the heating surface area of the body to be heated 3 is increased accordingly. Since it also moves in the direction of the arrow, the surface area having a width corresponding to the axial length of the coil unit 1 is uniformly heated without occurrence of uneven heating.

  Next, FIG. 2 shows a configuration of Example 2 in which the cross-sectional shape of the induction heating coil unit 1 is rectangular and the flatwise surface thereof is opposed to the heated body 3. The distribution of the alternating magnetic flux generated in the coil unit 1 of the second embodiment and the background of the induction heating surface area of the heated body 3 due to the scanning movement of the coil unit 1 are the same as those of the first embodiment described in FIG. .

  Here, the scanning of the coil unit 1 in the case where the induction heating coil unit 1 of Example 1 and Example 2 is scanned and moved over the entire surface area of the plate surface of the heating target 3 with respect to the heating target 3 having a large area. The movement path is shown in FIG. That is, as shown in the figure, the coil unit 1 is arranged so as to be opposed to one corner of the plate surface of the heated body 3 and is sequentially scanned in a zigzag manner as indicated by the arrow along the coordinate axis XY on the surface of the heated body 1. By moving, the entire surface of the heated body 3 can be induction heated. As a scanning driving means for moving the coil unit 1 along a desired scanning path, the induction heating coil unit 1 is mounted on the robot arm of the industrial robot 4 as shown in FIG. This can be easily realized by controlling movement on the plate surface of the heating element 3.

  Next, the results of considering the magnetic flux distribution, coil loss, etc. in various design models designed by the inventors etc. for the above-described solenoid type induction heating coil unit 1 will be described below.

  First, in the induction heating coil unit 1 of the basic design model (I) shown in FIG. 5A, both ends of the magnetic core 12 inserted in the inside of the solenoid coil 11 are arranged in the axial direction from the end of the solenoid coil 11. The structure protrudes somewhat, and is arranged close to the surface of the heated body 3 (block-shaped body) in parallel.

  With respect to the coil unit of this design model (I), when the object to be heated 3 is induction-heated by passing a high-frequency alternating current through the solenoid coil 11, the surface temperature of the object to be heated 3 rises to the target temperature with a short time energization. Before the heating, the coil conductors at both ends of the solenoid coil 11 abnormally generate heat and become red hot, so that induction heating becomes difficult. Therefore, when the magnetic flux distribution of the coil unit 1 is verified by a simulation method, the magnetic flux φ passing through the magnetic core 12 moves from the end portion of the magnetic core to the end region of the solenoid coil 11 as shown in FIG. It turned out that it was curved to pass and dispersed. For this reason, a local bias occurs in the current distribution of the coil conductor at the coil end of the solenoid coil 11, and this causes an increase in loss (resistance loss) at the coil end, resulting in abnormal heat generation (Joule heating) in the coil conductor. It is inferred that this occurred.

  On the other hand, the inventors added a magnetic pole piece 13 at the end of the magnetic core 12 as shown in FIGS. 6 and 7 as means for intensively guiding the magnetic flux φ having passed through the magnetic core 12 toward the heated body 3. When the design model (II) and design model (III) were verified in the same manner as described above, it was verified that the abnormal heat generation at the coil end, which was a problem in the design model (I), could be suppressed and the loss reduced. did it.

  That is, in the induction heating coil unit of the design model (II) shown in FIGS. 6A and 6B, the tip is extended toward the heated body 3 with some spacing from the magnetic core 12 at both ends of the magnetic core 12. An existing flat pole piece 13 is attached.

  On the other hand, in the induction heating coil unit of the design model (III) shown in FIGS. 7A and 7B, the pole piece 13 is joined to both ends of the solenoid coil 11 or close to both ends of the solenoid coil 11. The flange portion of the magnetic core 12 is formed by projecting toward the outer periphery of the solenoid coil 11.

  The magnetic pole piece 13 in the design models (II) and (III) is a ferrite sintered body (soft ferrite) or a laminated body of thin silicon steel plates to prevent an increase in iron loss, like the magnetic core 12 described above. In particular, in the design model (III) (see FIG. 7), the pole piece 13 is preferably formed integrally with the magnetic core 12 of the ferrite sintered body.

  Here, with respect to the design models (I), (II), and (III), the coil loss of each coil unit obtained under the condition that the induction heating coil unit is energized with 20 kW and the object to be heated 3 is induction heated. Is shown in Table 1 below. Here, although the total number of turns of the solenoid coil of the coil unit is 12 turns, Table 1 shows from the first turn to 6 turns in the center. Data from 7 turns to 12 turns at the end of the winding are omitted because they show almost symmetrical data from 1 turn to 6 turns.

  As can be seen from Table 1 above, according to the design models (II) and (III) in which the pole piece 13 is added to the magnetic core 12 with respect to the basic design model (I), each turn of the solenoid coil 11 Loss and total coil loss are greatly reduced with respect to the basic design model (I) in which no pole piece is added, and in particular in the design model (III) in which the pole piece 13 is joined to the coil end, the coil The effect of reducing the loss is remarkable.

  Next, for the solenoid induction heating coil unit 1 of the present invention, in addition to the addition of the magnetic pole piece 13 (see FIGS. 6 and 7), the winding pitch of the solenoid coil 11 is changed as follows: FIG. 8 shows an application example improved so that the heated body 3 can be efficiently heated uniformly by increasing the magnetic field strength and uniformity of the external magnetic field generated in the coil unit.

  In this embodiment, with respect to the number of turns of the entire solenoid coil corresponding to the design specifications of the coil unit, the winding pitch p1 of the coil conductor is made denser at both ends of the solenoid coil 11 as shown in the figure, and The winding pitch p2 of the coil conductor is set to be coarser (p1 <p2) so as to increase the winding.

  That is, the generated magnetic flux density in the axial direction of the solenoid coil in which the coil conductor is uniformly wound throughout the coil tends to decrease at both ends as compared with the center of the coil, but the coil pitch is changed as shown in FIG. By making the conductor sparsely and densely wound, the uniformity of the distribution in the axial direction of the magnetic flux density from the end of the coil unit 1 toward the heated body 3 can be improved, so that the heated body can be heated efficiently and uniformly. I can do it.

1: Solenoid induction heating coil unit 11: Solenoid coil 12: Magnetic core 13: Magnetic pole piece 2: High frequency power supply 3: Heated object φ: Alternating magnetic flux

Claims (7)

  An induction heating device that heats the surface of a heated object such as a metal plate or metal block, and an induction heating coil unit is configured by inserting a magnetic core inside a solenoid coil in which a coil conductor is wound in a cylindrical shape. Then, the circumferential surface of the induction heating coil unit is arranged in parallel with the surface of the heated body, and the coil unit is scanned along the heating surface area of the heated body while applying AC power to the solenoid coil in this state. An induction heating apparatus characterized by moving and heating an object to be heated.   2. The induction heating device according to claim 1, wherein the induction heating coil unit is configured to have a flat shape such as an elliptical shape or a rectangular shape in cross section, and the flatwise surface thereof is disposed opposite to the object to be heated. A feature of the induction heating device.   The induction heating apparatus according to claim 1 or 2, wherein the magnetic pole piece for intensively guiding the alternating magnetic flux passing through the magnetic core toward the heated body is provided at both ends of the magnetic core of the induction heating coil unit. An induction heating apparatus characterized by comprising:   4. The induction heating apparatus according to claim 3, wherein the magnetic pole piece is disposed in the vicinity of both ends of the solenoid coil and has a shape projecting in the outer peripheral direction of the solenoid coil.   5. The induction heating device according to claim 1, wherein the magnetic core and pole piece magnetic body provided in the induction heating coil unit is a ferrite sintered body or a laminate of thin steel plates. Induction heating device.   In the induction heating device according to any one of claims 1 to 5, the solenoid coil wound around the outer periphery of the magnetic core of the induction heating coil unit has a tight winding pitch of the coil conductor at both ends of the coil. An induction heating apparatus characterized in that a winding pitch of a coil conductor in a central portion of the coil is set roughly.   The induction heating device according to any one of claims 1 to 6, wherein the coil unit is mounted on a scanning drive device such as an industrial robot as a scanning movement unit of the induction heating coil unit, and the surface of the object to be heated is mounted. An induction heating apparatus characterized by being moved by scanning.

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