JP6830776B2 - Induction heating device and induction heating method - Google Patents

Description

According to the present invention, when the induction heating coil is moved relative to the surface to be heated to heat the surface to be heated, the peripheral portion of the object to be heated can be easily heated, and the object to be heated is heated. The present invention relates to an induction heating device and an induction heating method capable of easily leveling the temperature over the entire surface.

Conventionally, as a method of heating the heated surface of an object to be heated in a non-contact manner, a method of blowing a high-temperature gas and heating using heat transfer of the surface to be heated, or a heating element such as a heating wire heater is heated. A method of bringing an object close to the surface to be heated and heating it with radiant heat from a heating element, a method of applying infrared rays such as a lamp heater to the surface to be heated and heating it with radiant heat by infrared rays, and guiding to the surface to be heated using an electromagnetic induction coil. There is a method of inducing an electric current and heating the surface to be heated by the resistance heat due to the material of the object to be heated.

Here, when the surface to be heated is heated by using the induction heating coil, the induction heating coil is moved to heat the surface to be heated so as to be stroked evenly. As a method of moving the induction heating coil, the induction heating coil is attached to the wrist portion at the tip of the robot arm, and the induction heating coil is moved according to the shape of the surface to be heated according to the program of the robot.

In Patent Document 1, when an object to be heated is heated by using an induction heating coil, a synthetic coil shape formed by synthesizing two substantially V-shaped coils according to the width of the object to be heated. Is described to be variable to reduce overheating at the edge of the object to be heated.

JP-A-2010-24529

By the way, when an induction heating coil having a heating surface smaller than the surface to be heated of the object to be heated is used, the induction heating coil is moved to heat the surface to be heated so as to be evenly stroked. Here, when heating the peripheral portion of the object to be heated, a part of the induction heating coil, for example, 30% of the diameter is made to protrude outside the object to be heated so that the induced current flows through the peripheral portion of the object to be heated. Is heating.

However, if a part of the induction heating coil protrudes outside the heating object, the impedance of the heating object in the induction heating coil increases, it becomes difficult for current to flow through the induction heating coil, and the peripheral portion of the heating object is heated. It becomes difficult to do.

Further, when the induction heating coil is moved to heat the object to be heated by using a robot or the like, the induction heating coil is moved from the outside of the heated area to the inside of the heated area of the heated object. Due to the impedance, the current starts to flow in the induction heating coil after the induction heating coil has sufficiently entered the heated region of the object to be heated, so that the peripheral portion of the object to be heated cannot be sufficiently heated.

The present invention has been made in view of the above, and when the induction heating coil is moved relative to the heated surface of the object to be heated to heat the surface to be heated, the peripheral portion of the object to be heated An object of the present invention is to provide an induction heating device and an induction heating method capable of facilitating heating and easily equalizing the temperature of the entire surface to be heated of the object to be heated.

In order to solve the above-mentioned problems and achieve the object, the induction heating device according to the present invention includes an object to be heated having a surface to be heated and an induction heating coil having a heating surface smaller than the surface to be heated. Is an induction heating device that heats the surface to be heated of the object to be heated by relatively moving them in a non-contact manner, and a heating auxiliary material having the same surface as the surface to be heated is placed on the peripheral edge of the object to be heated. The heating auxiliary material is characterized in that the electric conductivity is within a predetermined range set in advance centering on the electric conductivity of the object to be heated.

Further, the induction heating device according to the present invention is characterized in that, in the above invention, the electric conductivity of the heating auxiliary material is a value equivalent to the electric conductivity of the object to be heated.

Further, the induction heating device according to the present invention is characterized in that, in the above invention, the width of the heating auxiliary material from the peripheral edge of the heating object exceeds the diameter of the induction heating coil.

Further, the induction heating device according to the present invention is characterized in that, in the above invention, the induction heating coil is a spiral disk coil.

Further, in the induction heating method according to the present invention, the heating object having a surface to be heated and the induction heating coil having a heating surface smaller than the surface to be heated are relatively moved in a non-contact manner to heat the object. In an induction heating method for heating the surface to be heated of an object, a heating auxiliary material having the same surface as the surface to be heated is arranged on the periphery of the object to be heated, and the electric conductivity of the heating auxiliary material is provided. Is within a predetermined range set in advance centering on the electric conductivity of the object to be heated.

According to the present invention, a heating auxiliary material having the same surface as the surface to be heated is arranged on the periphery of the object to be heated, and the electric conductivity of the heating auxiliary material is set in advance centering on the electric conductivity of the object to be heated. Since the object to be heated is heated within the set predetermined range, when the peripheral edge of the object to be heated is heated by the induction heating coil, the impedance to the induction heating coil does not increase and the induced current flows sufficiently. Sufficient heat generation is generated. That is, by providing the heating auxiliary material, it becomes easy to heat the peripheral portion of the object to be heated, and it is possible to easily equalize the temperature of the entire surface of the object to be heated.

FIG. 1 is a schematic view showing an overall configuration of an induction heating device according to an embodiment of the present invention. FIG. 2 is a diagram showing a state in which the induction heating coil is moved in the central portion not including the peripheral edge of the object to be heated. FIG. 3 is a diagram showing a temperature distribution in a direction perpendicular to the moving direction in the passing heating region after the movement of the induction heating coil shown in FIG. FIG. 4 is a diagram showing a state in which the induction heating coil is moved including the peripheral edge of the object to be heated. FIG. 5 is a diagram showing a temperature distribution in a direction perpendicular to the moving direction in the passing heating region after the movement of the induction heating coil shown in FIG. FIG. 6 is a diagram showing an example of arrangement of the heating auxiliary material when the object to be heated moves relative to each other in one direction.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(overall structure)
FIG. 1 is a schematic view showing an overall configuration of an induction heating device according to an embodiment of the present invention. As shown in FIG. 1, the induction heating device includes a robot arm 3 having an induction heating coil 2 attached to a wrist portion at the tip, an infrared thermography 4, a control unit 5, a display unit 6, an operation unit 7, and a storage unit 8. Has. Further, the control unit 5 includes a temperature detection unit 11, a temperature distribution calculation unit 12, and a heating control unit 13. Further, the storage unit 8 has the target surface temperature distribution information D1, the surface temperature distribution image D2, and the heating change control information D3. The induction heating coil 2, the robot arm 3, the infrared thermography 4, the display unit 6, the operation unit 7, and the storage unit 8 are connected to the control unit 5.

The induction heating coil 2 is, for example, a spiral disk coil wound in a circular shape. The position and orientation of the induction heating coil 2 can be changed by the robot arm 3. The movement path, movement speed, and output including the position and orientation of the induction heating coil 2 are controlled by the control unit 5. The induction heating coil 2 moves close to the surface to be heated 1a of the object to be heated 1 containing the conductive material, and heats the surface 1a to be heated. The induction heating coil 2 generates a magnetic field by a high-frequency current supplied from a power source (not shown), generates an eddy current in the object 1 to be heated, and heats the surface to be heated 1a by the resistance heat. Since the surface to be heated 1a is larger than the size of the induction heating coil 2, the induction heating coil 2 is moved to heat the surface to be heated 1a so as to be stroked evenly. In the present embodiment, the induction heating coil 2 is moved with respect to the surface to be heated 1a, but the surface to be heated 1a may be moved with respect to the induction heating coil 2. Further, both the induction heating coil 2 and the surface to be heated 1a may be moved. That is, any mechanism may be used as long as the positional relationship between the surface to be heated 1a and the induction heating coil 2 can be relatively moved.

Around the object to be heated 1, the object to be heated is located on the same plane as the surface to be heated 1a of the object to be heated 1 and close to the peripheral edge of the surface 1a to be heated, with a width wider than the diameter of the induction heating coil 2. The heating auxiliary material 20 is arranged so as to surround the object 1. In the heating auxiliary material 20 shown in FIG. 1, four heating auxiliary materials 21 to 24 are arranged on each side of the object 1 to be heated. The upper surfaces 21a to 24a of the heating auxiliary materials 21 to 24 form the same surface as the surface to be heated 1a. The heating auxiliary material 20 may be, for example, an integrated heating auxiliary material 21 to 24.

The material of the heating auxiliary material 20 is preferably the same as the material of the object to be heated 1. In particular, the electric conductivity of the heating auxiliary material 20 preferably has a value equivalent to the electric conductivity of the object 1 to be heated. The electric conductivity of the heating auxiliary material 20 may have a value within a predetermined range set in advance centering on the electric conductivity of the object 1 to be heated. The material of the heating auxiliary material 20 is equivalent to or similar to the material of the heating object 1, as described later, when the peripheral edge of the heating object 1 is heated, an electric current easily flows through the heating auxiliary material 20. This is because the impedance to the induction heating coil 2 does not increase, and the peripheral edge of the object 1 to be heated can be easily heated.

The infrared thermography 4 captures a surface temperature distribution image of an infrared region with respect to the surface to be heated 1a at predetermined sampling intervals. The temperature detection unit 11 acquires the surface temperature distribution image captured by the infrared thermography 4 and stores it in the storage unit 8 as the surface temperature distribution image D2.

The temperature distribution calculation unit 12 obtains the average value of each corresponding pixel in the plurality of surface temperature distribution images D2 accumulated at predetermined sampling times from the start to the end of one mobile heat treatment, and obtains the average value of the average value. Find the surface temperature distribution according to. The average value may be obtained not in units of each pixel of the surface temperature distribution image D2 but in units of preset mesh regions. The preset mesh area unit is composed of a plurality of adjacent pixels. Further, each pixel unit may be treated as a preset mesh area unit.

In the heating control unit 13, the target surface temperature distribution indicated by the target surface temperature distribution information D1 stored in the storage unit 8 and the surface temperature distribution calculated by the temperature distribution calculation unit 12 are the same (within the allowable range). Change any one or more of the movement path including the distance and orientation between the induction heating coil 2 and the surface to be heated 1a, the movement speed during the movement heating treatment, and the output of the induction heating coil 2 next. One mobile heat treatment is set, and the execution of the set one mobile heat treatment is controlled. The change of the mobile heat treatment is determined with reference to the heat change control information D3 in the storage unit 8.

The display unit 6 displays and outputs various information such as the surface to be heated 1a, the moving path and moving state of the induction heating coil 2, and the surface temperature distribution.

The operation unit 7 gives a control instruction to the control unit 5. The operation unit 7 is realized by a keyboard or a pointing device.

Next, the temperature distribution when the induction heating coil 2 is moved on the heating object 1 to heat the heating object 1 will be described. First, FIG. 2 is a diagram showing a state in which the induction heating coil 2 is moved in the A1 direction at a central portion that does not include the peripheral edge of the object 1 to be heated. Further, FIG. 3 is a diagram showing a temperature distribution in a direction perpendicular to the moving direction in the passing heating region E1 after the movement of the induction heating coil 2 shown in FIG.

The temperature distribution curve RF1 shown in FIG. 3 has a mountain-shaped shape in which the temperature rises from the periphery of the induction heating coil 2 toward the center, but the central portion RF1a has a concave shape and a small mortar shape in which the temperature drops slightly is formed. Will be done. This is because there is no coil conductor in the central hole 2a of the induction heating coil 2, no magnetic field lines are generated, no induced current flows directly under the hole 2a, and no heat is generated. In FIG. 3, the position P0 is a position corresponding to the center of the hole 2a. The maximum temperature in the temperature distribution curve RF1 shown in FIG. 3 is the temperature Ta.

FIG. 4 is a diagram showing a state in which the induction heating coil 2 is moved in the A1 direction including the peripheral edge of the object 1 to be heated. Further, FIG. 5 is a diagram showing a temperature distribution in a direction perpendicular to the moving direction in the passing heating region E2 after the movement of the induction heating coil 2 shown in FIG.

Similar to the temperature distribution curve RF1, the temperature distribution curve RF2 shown in FIG. 5 has a chevron shape having portions RF2a and RF2b in which the temperature rises from the periphery of the induction heating coil 2 toward the center, but the central portion. It decreases once in the vicinity, and in the central part corresponding to the position P0, the temperature suddenly decreases to zero. Further, the temperature of the temperature distribution curve RF2 is generally lower than the temperature of the temperature distribution curve RF1. The reason why the temperature is low at the central portion of the temperature distribution curve RF2 is that the heating object 1 and the heating auxiliary material 20 are electrically separated and an induced current does not flow. The reason why there is a rapid temperature rise near the center of the temperature distribution curve RF2 is that the induced current corresponding to the coil shape flows individually to each of the heating object 1 and the heating auxiliary material 20, and the heating object 1 and the heating auxiliary material 20 are heated. This is because the density of the induced current in the vicinity of the peripheral edge of the material 20 increases. Further, the temperature of the temperature distribution curve RF2 is generally lower than the temperature of the temperature distribution curve RF1 when the induced currents individually flow through the heating target 1 and the heating auxiliary material 20, and the heating target is heated. This is because the impedance becomes larger than the impedance when the induced current in which 1 and the heating auxiliary material 20 are integrated flows, and the induced current becomes difficult to flow.

Here, the temperature distribution curve RF3 shown in FIG. 5 shows the temperature distribution when the induction heating coil 2 is moved in the same manner as in FIG. 4 without providing the heating auxiliary material 20. When the heating auxiliary material 20 is not provided, the induced current flows only on the side of the object to be heated 1, the impedance to the induction heating coil 2 becomes very large, and as a result, the induced current becomes difficult to flow and the heat generation becomes small.

As shown in FIG. 5, when the heating auxiliary material 20 is provided, the impedance with respect to the induction heating coil 2 is reduced as compared with the case where the heating auxiliary material 20 is not provided, and is larger than when the heating auxiliary material 20 is not provided. Induced current flows and heat generation due to eddy current increases.

In the present embodiment in which the heating auxiliary material 20 is provided, the temperature is generally lower than that when the induction heating coil 2 moves without including the peripheral edge of the heating object 1, but the heating auxiliary material 20 is not provided. It is possible to obtain a sufficiently large temperature by heating as compared with the above.

That is, in the present embodiment, by providing the heating auxiliary material 20, it becomes easy to heat the peripheral portion of the object to be heated 1, and it becomes easy to equalize the temperature in the entire area of the object to be heated 1. In addition, the degree of freedom in selecting the movement path of the induction heating coil 2 is increased, and the movement path can be easily created.

When heating the peripheral edge of the object 1 to be heated, the overall temperature is lower than that when the induction heating coil 2 is heated so as not to straddle the peripheral edge of the object 1 to be heated. Therefore, for example, the induction heating coil 2 is used. The heating temperature is increased by changing the amount and frequency of the flowing current, but the change in the amount of current and frequency is smaller than when the induction heating coil 2 is heated so as not to straddle the peripheral edge of the object 1 to be heated. , The heating control of the inverter etc. does not become unstable, and stable heating control can be performed.

Further, as shown in FIG. 6, when the object to be heated 101 is relatively moved in the A2 direction, it is not necessary to provide a heating auxiliary material at the end in the A2 direction. That is, as shown in FIG. 6, the heating auxiliary materials 121 and 123 may be provided on the side surfaces of the object to be heated 101 along the relative moving direction. Also in this case, the surface to be heated 101a and the upper surfaces 121a and 123a of the object to be heated 101 are the same surface.

In the above-described embodiment, the object 1 to be heated is rectangular, but the object 1 is not limited to this, and may have various shapes such as a circular shape and an elliptical shape.

Further, the above-mentioned heating object 1 has been described on the premise of a conductive material such as metal, but the present invention is not limited to this, and for example, a composite material of a conductive fiber such as carbon and a resin, for example, CFRP (Carbon Fiber Reinforced Plastics) ) May be. A paint such as a resin that is cured by a polymerization reaction may be coated on the surface to be heated of the conductive object to be heated. The heating control in this case is to bake the paint applied to the object to be heated.

Since the magnetic field lines easily pass through a composite material such as CFRP, it is preferable to stack a plurality of CFRPs and heat them at the same time.

Here, heating of CFRP is suitable as preheating during molding of CFRP. It should be noted that this embodiment can also be applied as preheating of a mold used at the time of molding CFRP or the like. When the mold is preheated, the end portion of the mold is sufficiently heated, so that heat release at the end portion of the molding target can be prevented and high-precision molding becomes possible.

1 Object to be heated 1a, 101a Surface to be heated 2 Inductive heating coil 3 Robot arm 4 Infrared thermography 5 Control unit 6 Display unit 7 Operation unit 8 Storage unit 11 Temperature detection unit 12 Temperature distribution calculation unit 13 Heating control unit 20 to 24, 121 , 123 Heating auxiliary materials 21a to 24a, 121a, 123a Top surface D1 Target surface temperature distribution information D2 Surface temperature distribution image D3 Heating change control information P0 Position RF1 to RF3 Temperature distribution curve Ta Temperature

Claims (3)

The object to be heated and the induction heating coil, which is a spiral disk coil having a surface smaller than the surface to be heated , are relatively moved in a non-contact manner to the object to be heated. An induction heating device that heats the surface to be heated.
A heating auxiliary material having the same surface as the surface to be heated is arranged on the periphery of the heating object, and the electric conductivity of the heating auxiliary material is set in advance centering on the electric conductivity of the heating object. range der is, the width from the periphery of the heating object of the heating auxiliary material, induction heating device characterized by a diameter exceeding of the induction heating coil. The induction heating device according to claim 1, wherein the electric conductivity of the heating auxiliary material is a value equivalent to the electric conductivity of the object to be heated. The object to be heated and the induction heating coil, which is a spiral disk coil having a surface smaller than the surface to be heated , are relatively moved in a non-contact manner to the object to be heated. An induction heating method that heats the surface to be heated.
A heating auxiliary material having the same surface as the surface to be heated is arranged on the periphery of the heating object, and the electric conductivity of the heating auxiliary material is set in advance centering on the electric conductivity of the heating object. range der is, the width from the periphery of the heating object of the heating auxiliary material, induction heating method characterized by exceeding the diameter of the induction heating coil.

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