JP2018037168A - Induction heating device and induction heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating device and an induction heating method that can easily make the temperature distribution of a whole heated surface even by flattening the central portion of a temperature distribution profile vertical to a travel direction.SOLUTION: An induction heating device heats a heating object 1 by moving, without contact, the heating object 1 including a heated surface 1u relative to an induction heating coil 2 including a heating surface smaller than the heated surface 1u and having a hole 2a formed at a central portion. The induction heating device controls heating of the heating object 1 using a travel path RT1, i.e. a first travel path of the induction heating coil 2 and a travel path RT2, i.e. a second travel path of the induction heating coil 2 shifted by a prescribed distance Δd in a direction vertical to the travel path RT1 as one combination travel path. The prescribed distance Δd is a value obtained by adding or subtracting an allowable distance to/from half of a hole diameter d of the induction heating coil 2.SELECTED DRAWING: Figure 2

Description

  The present invention has a heating surface that is smaller than the surface to be heated of the object to be heated, and moves the induction heating coil having a hole formed in the central portion to raise the temperature of the object to be heated. The present invention relates to an induction heating apparatus and an induction heating method capable of easily flattening a central portion of a temperature distribution profile perpendicular to the surface to make the temperature distribution of the entire heated surface uniform.

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

  Here, when the surface to be heated is heated using the induction heating coil, the induction heating coil is moved to heat the surface to be heated evenly. As a method of moving the induction heating coil, an induction heating coil is attached to the wrist portion at the tip of the robot arm, and the induction heating coil is moved in accordance with the shape of the surface to be heated in accordance with the program of the robot.

  In Patent Document 1, when a thin plate-like object to be heated is heated using an induction heating coil, two substantially V-shaped coils are synthesized according to the width of the object to be heated. There is a description that the synthetic coil shape is made variable to reduce overheating at the edge of the object to be heated.

JP 2010-245029 A

  By the way, when the induction heating coil has a heating surface that is smaller than the surface to be heated of the object to be heated and the object to be heated is heated by using this induction heating coil, the induction heating coil is heated as described above. Move so that the heated surface of the object is evenly stroked.

  The temperature distribution generated by the movement of the induction heating coil has a bell-shaped profile with respect to the direction perpendicular to the moving direction. This temperature distribution profile is symmetrical, but has a concave shape at the center and a shape in which the temperature decreases. A concave temperature-decreasing part is formed in the central part of this temperature distribution profile. The induction heating coil is heated only in the part directly under the coil shape, and the induction heating coil forms a hole in the coil central part. This is because the portion directly below the hole is not heated.

  As a result, in the temperature distribution profile formed by the movement of the induction heating coil, a shape having a temperature difference is formed in the central portion, a uniform temperature distribution is not formed, and heating that makes the temperature distribution of the entire heated surface uniform. It becomes difficult to control.

  The present invention has been made in view of the above, and has a heating surface that is smaller than the surface to be heated of the object to be heated, and moves the induction heating coil in which a hole is formed in the center portion to be heated. Provided is an induction heating apparatus and an induction heating method capable of easily flattening the central portion of a temperature distribution profile perpendicular to the moving direction and making the temperature distribution of the entire surface to be heated uniform when heating an object by heating. The purpose is to do.

  In order to solve the above-described problems and achieve the object, an induction heating apparatus according to the present invention has a heating object having a surface to be heated and a heating surface smaller than the surface to be heated. An induction heating device that heats the object to be heated by relatively moving an induction heating coil having a hole formed in a non-contact manner, the first movement path of the induction heating coil, and the first movement Heating control of the heating object is performed using the second movement path of the induction heating coil shifted by a predetermined distance in a direction perpendicular to the path as one synthetic movement path.

  The induction heating apparatus according to the present invention is characterized in that, in the above invention, the predetermined distance is a value obtained by increasing or decreasing the allowable distance to ½ of the diameter of the hole of the induction heating coil.

  In the induction heating apparatus according to the present invention, in the above invention, the permissible distance is a second temperature path shifted by a predetermined distance from the first temperature distribution profile in a direction perpendicular to the first distance. The temperature difference in the center portion of the combined temperature distribution profile obtained by combining the second temperature distribution profiles in the direction perpendicular to the distance is a distance within a predetermined range.

  The induction heating apparatus according to the present invention is characterized in that, in the above invention, the object to be heated is a CFRP plate material in which carbon fibers are knitted into a resin.

  In addition, the induction heating method according to the present invention is a non-contact method between 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 and having a hole formed in the central portion. The induction heating method of heating the object to be heated by relatively moving the induction object, wherein the induction heating coil is shifted by a predetermined distance in a direction perpendicular to the first movement path of the induction heating coil and the first movement path. Heating control of the heating object is performed using the second moving path of the heating coil as one synthetic moving path.

  In the induction heating method according to the present invention as set forth in the invention described above, the predetermined distance is a value obtained by increasing or decreasing the allowable distance to ½ of the diameter of the hole of the induction heating coil.

  According to the present invention, the first movement path of the induction heating coil and the second movement path of the induction heating coil shifted by a predetermined distance in a direction perpendicular to the first movement path are used as one synthetic movement path. Since the heating object is controlled to be heated, the central portion of the temperature distribution profile perpendicular to the moving direction can be flattened, and the temperature distribution of the entire heated surface can be made uniform easily.

FIG. 1 is a schematic diagram showing an overall configuration of an induction heating apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a positional relationship between the first movement route and the second movement route. FIG. 3 is a diagram showing a first temperature distribution profile when heated by the first movement path, a second temperature distribution profile when heated by the second movement path, and a combined temperature distribution profile. FIG. 4 is a diagram showing a specific first temperature distribution profile and second temperature distribution profile. FIG. 5 is a diagram showing a combined temperature distribution profile when the predetermined distance is not shifted. FIG. 6 is a diagram showing a specific synthesis temperature distribution profile. FIG. 7 is a diagram showing a change in the unevenness ratio of the temperature distribution in the central portion when the hole diameter is a variable and the predetermined distance is changed.

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

(overall structure)
FIG. 1 is a schematic diagram showing an overall configuration of an induction heating apparatus according to an embodiment of the present invention. As shown in FIG. 1, the induction heating apparatus includes a robot arm 3 having an induction heating coil 2 attached to the wrist at the tip, a control unit 5, a display unit 6, an operation unit 7, and a storage unit 8.

  The induction heating coil 2 is, for example, a spiral disk coil wound in a circular shape. The position and posture of the induction heating coil 2 can be changed by the robot arm 3. The movement path, the movement speed, and the output including the position and posture of the induction heating coil 2 are controlled under the control unit 5. The induction heating coil 2 induction-heats the heating object 1 which is a flat CFRP plate material in which carbon fibers are knitted into resin. The induction heating coil 2 heats the heating object 1 while moving close to the upper surface 1 u that is the heated surface of the heating object 1.

  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 heating object 1, and heats the heating object 1 by the resistance heat. Since the upper surface 1u is larger than the size of the induction heating coil 2, the induction heating coil 2 is moved to heat the upper surface 1u so that it is evenly stroked. In this embodiment, the induction heating coil 2 is moved with respect to the upper surface 1u. However, the upper surface 1u may be moved with respect to the heating target 1 with respect to the induction heating coil 2. Further, both the induction heating coil 2 and the heating object 1 may be moved. That is, any mechanism can be used as long as the positional relationship between the upper surface 1u and the induction heating coil 2 can be relatively moved.

  The display unit 6 displays and outputs various information such as the upper surface 1 u, the movement path and movement state of the induction heating coil 2, and the temperature distribution state of the heating object 1 detected by infrared thermography (not shown).

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

(Movement path of induction heating coil)
As described above, the induction heating coil 2 heats the heating object 1 while moving so as to evenly stroke the upper surface 1u of the heating object 1. For example, as shown in FIG. 2A, the induction heating coil 2 moves on the entire upper surface 1u along a first movement path including a movement path RT1 in which the center C1 moves in the Y direction at the position d1 in the X direction. Heat. After heating by the first movement path, as shown in FIG. 2B, the induction heating coil 2 is a second movement path including a movement path RT2 in which the center C1 moves in the Y direction at the position d2 in the X direction. The entire upper surface 1u is heated while moving.

  The second movement route is a movement route shifted by a predetermined distance Δd in a direction perpendicular to the first movement route. For example, as shown in FIG. 2, the travel route RT2 is shifted from the travel route RT1 by a predetermined distance Δd in the X direction.

(Synthetic temperature distribution profile)
The temperature distribution profile perpendicular to the moving direction of the induction heating coil 2 forms a bell shape, and has a concave shape in which the temperature is lowered at the center. As shown in FIG. 2, the center portion of the induction heating coil 2 is not wound with a coil, a hole 2a having a hole diameter d is formed, and an induction is formed on the upper surface 1u of the portion directly below the hole 2a. This is because current does not flow and is not heated. For example, as shown in FIG. 3A, the first temperature distribution profile PF1 in the direction perpendicular to the movement route RT1 after passing through the movement route RT1 has a concave shape around the position d1.

  On the other hand, the second temperature distribution profile PF2 in the direction perpendicular to the movement path RT2 after passing through the movement path RT2 is also concave around the position d2. Here, since the movement path RT2 is shifted by a predetermined distance Δd with respect to the movement path RT1, the second temperature distribution profile PF2 is also shifted by a predetermined distance Δd with respect to the first temperature distribution profile PF1. Therefore, when the induction heating coil 2 passes through the movement path RT1 for the first time and the movement path RT2 for the second time, as shown in FIG. 3B, the first temperature distribution profile PF1 and the second temperature profile are obtained. A combined temperature distribution profile PF3 obtained by combining PF2 can be formed. It is assumed that the moving speed, frequency, and current amount of the induction heating coil 2 are the same. The maximum temperature indicated by the combined temperature distribution profile PF3 is about twice the maximum temperature of the first temperature distribution profile PF1 and the second temperature distribution profile PF2.

  In the central portion of the synthesized temperature distribution profile PF3, the temperature difference is canceled out and a uniform temperature distribution is formed. Accordingly, since the central portion of the synthesized temperature distribution profile PF3 is flattened, the temperature distribution of the entire heated surface 1u can be easily made uniform. That is, the control unit 5 heats the first movement path and the second movement path shifted by a predetermined distance Δd in the direction perpendicular to the first movement path as a single combined movement path. By controlling, the temperature distribution of the entire heated surface 1u can be made uniform easily. One combined movement route is treated as a movement route with a pair of the first movement route and the second movement route for control.

(Predetermined distance Δd)
Here, FIG. 4 shows a first temperature distribution profile PF11 and a second temperature distribution profile PF12 when a specific induction heating coil 2 is used. The induction heating coil 2 has a coil outer diameter D of 200 mm and a hole diameter d of 70 mm, and a predetermined distance Δd as a shift amount is set to 35 mm which is ½ of the hole diameter d. The reason why the predetermined distance Δd is ½ of the hole diameter d is that the distance between the maximum values P1 and P2 of the first temperature distribution profile PF11 and the second temperature distribution profile PF12 is almost equal to the hole diameter d. This is because the maximum value P1 portion is considered to cancel out the concave portion in the central portion.

  FIG. 5 shows the combined temperature distribution profile PF21 when the predetermined distance Δd is zero. This combined temperature distribution profile PF21 has a total temperature that is doubled, that is, the temperature ratio after synthesis with respect to that before synthesis is only doubled, the shape is not changed, and the temperature difference in the central portion is large.

  On the other hand, FIG. 6 shows the combined temperature distribution profile PF13 when the predetermined distance Δd is ½ of the hole diameter d. As shown in FIG. 6, the synthesized temperature distribution profile PF13 has a substantially flat shape with a small temperature difference at the central portion E.

  FIG. 7 shows changes in the unevenness ratio of the temperature distribution (temperature difference of the central portion E) when the coil outer diameter D is constant at 200 mm and the predetermined distance Δd changes with respect to the hole diameter d of 50 mm, 70 mm, and 90 mm. ing. The concave / convex ratio indicates the central concave amount with respect to the maximum value of the central portion E. When the concave / convex ratio is negative, a convex shape is generated at the center, and when the concave / convex ratio is positive, a concave shape is generated at the center. Indicates that From the results shown in FIG. 7, the predetermined distance Δd is 23 mm, 32 mm, and 49 mm with respect to the hole diameter d of 50 mm, 70 mm, and 90 mm, and the unevenness ratio is 0. That is, the predetermined distance Δd is approximately ½ of the hole diameter d, and the unevenness ratio is close to zero. Therefore, by setting 1/2 of the hole diameter d to the predetermined distance Δd, it is possible to obtain a combined temperature distribution profile with a small unevenness ratio of the central portion E.

  The predetermined distance Δd is not limited to ½ of the hole diameter d, and the concave / convex ratio can be reduced if the allowable distance Δα is increased or decreased, that is, within a range of (d / 2) ± Δα.

  In the above-described embodiment, the heating object 1 is described as a CFRP plate. However, the heating object 1 can be similarly applied even if it is a metal flat plate.

  In addition, when the heating target 1 is a CFRP plate material, it is efficient to heat in a state where a plurality of CFRP plate materials are overlapped. This is because the lines of magnetic force emitted from the induction heating coil 2 are easily transmitted because the main material of the CFRP plate is resin. The magnetic field lines generate an eddy current by causing an induced current to flow through the woven carbon fiber in the resin of the CFRP plate material, thereby heating the carbon fiber. The surrounding resin temperature is also raised by the heat generated by the carbon fibers. The temperature of the CFRP plate is increased until the resin softening temperature is reached. The reason for raising the temperature to the resin softening temperature is that the CFRP plate material is then subjected to a molding process such as a press process.

  In the above-described embodiment, the heating object is rectangular, but is not limited thereto, and may be various shapes such as a circle and an ellipse.

DESCRIPTION OF SYMBOLS 1 Heating object 1u Upper surface 2 Induction heating coil 2a Hole 3 Robot arm 5 Control part 6 Display part 7 Operation part 8 Storage part D Coil outer diameter d Hole diameter E Center part PF1, PF11 1st temperature distribution profile PF2, PF12 1st 2 temperature distribution profile PF3, PF13 Composite temperature distribution profile RT1, RT2 Movement path Δd Predetermined distance

Claims (6)

A heating object having a surface to be heated and an induction heating coil having a heating surface smaller than the surface to be heated and having a hole formed in a central portion thereof are relatively moved in a non-contact manner to form the heating object. An induction heating device for heating
The heating object is defined as a single combined movement path including a first movement path of the induction heating coil and a second movement path of the induction heating coil shifted by a predetermined distance in a direction perpendicular to the first movement path. An induction heating apparatus characterized by controlling heating.   The induction heating apparatus according to claim 1, wherein the predetermined distance is a value obtained by increasing or decreasing an allowable distance to ½ of a diameter of a hole of the induction heating coil.   The allowable distance is a combination of a first temperature distribution profile in a direction perpendicular to the first movement path and a second temperature distribution profile in a direction perpendicular to the second movement path shifted by the predetermined distance. The induction heating apparatus according to claim 2, wherein the temperature difference in the central portion of the temperature distribution profile is a distance within a predetermined range.   The induction heating apparatus according to any one of claims 1 to 3, wherein the heating object is a CFRP plate material in which carbon fibers are knitted into a resin. A heating object having a surface to be heated and an induction heating coil having a heating surface smaller than the surface to be heated and having a hole formed in a central portion thereof are relatively moved in a non-contact manner to form the heating object. An induction heating method for heating
The heating object is defined as a single combined movement path including a first movement path of the induction heating coil and a second movement path of the induction heating coil shifted by a predetermined distance in a direction perpendicular to the first movement path. An induction heating method characterized by controlling heating.   The induction heating method according to claim 5, wherein the predetermined distance is a value obtained by increasing or decreasing the allowable distance to ½ of the diameter of the hole of the induction heating coil.

Images