JP2020129471A - Induction heating apparatus - Google Patents

Abstract

To prevent temperature distribution of a heated body from getting worse due to heat storage in a grip member by heat conduction from the heated body, in continuous production, when a thick adiabator is used as a grip member of the heated body, in induction heating.SOLUTION: An induction heating apparatus comprising an induction heating coil 100 having a cylindrical heated body placed inside, and assistance backing materials 111a, 111b placed in the induction heating coil, and generating heat by producing an eddy current, further includes grip members 110a, 110b interposing between a heated body 120 and the assistance backing materials and supporting the heated body. The induction heating apparatus can support a first heated body, and a second heated body having an outer diameter larger than that of the first heated body. The grip members 110a, 110b support the heated body so that the distance between one end of the first heated body and the assistance backing material becomes longer than the distance between one end of the second heated body and the assistance backing material when the second heated body is placed in the induction heating coil, and is composed of a non-magnetic material.SELECTED DRAWING: Figure 1

Description

The present invention relates to a device for induction heating a cylindrical object to be heated.

An electrophotographic photosensitive member (hereinafter also referred to as a photosensitive drum) mounted on an electrophotographic apparatus generally has a cylindrical metal base layer on which a photosensitive layer is formed. Further, a method is known in which a protective layer is formed on the surface of the photosensitive layer, and the protective layer is cured by electron beam irradiation and heating to improve the durability of the photosensitive drum. At this time, there is a demand for a heating device capable of uniformly heating the photosensitive drum for the purpose of reducing the hardness variation of the protective layer.

A method using hot air heating, light heating, or induction heating has been tried to heat the photosensitive drum. In particular, the method using induction heating is effective because it can be heated in a short time. Induction heating is a heating method in which when a magnetic field changes across a conductive material, an eddy current is generated near the surface of the conductive material, and the object to be heated is heated by its Joule heat generation. At this time, an eddy current flowing in the conductive material generates a magnetic field that prevents the change of the magnetic field. In the induction heating, only the conductive material is heated, and if the material has sufficiently low electric conductivity, it is not heated even in the magnetic field generation region.

Further, the amount of heat generated by the heated body differs depending on the relative magnetic permeability of the heated body. If the object to be heated is a material having a high relative magnetic permeability (ferromagnetic material) such as iron or nickel, a large amount of eddy current will be generated even with a slight change in the magnetic field, and the amount of heat generated will increase. On the contrary, if the object to be heated is a material (nonmagnetic material) having a low relative magnetic permeability such as aluminum or copper, the amount of eddy current generated is small, and the amount of heat generated is smaller than that of a ferromagnetic material. Furthermore, the amount of heat generated by the cylindrical object to be heated also differs depending on the outer diameter of the object to be heated. The larger the outer diameter of the object to be heated, the more eddy current is generated and the larger the amount of heat generation.

A spiral induction heating coil is often used to heat a cylindrical object to be heated, such as a photosensitive drum. Further, when heating a plurality of types of objects to be heated having different lengths and diameters with a common induction heating coil, the magnetic field generation region generated by the induction heating coil and the length of the longest object to be heated may match. It is common to use induction heating coils. However, when a short length of the object to be heated is heated by using the induction heating coil, there is a problem that the end portion of the object to be heated generates excessive heat as compared with other portions. This is because at the end of the heated body, eddy currents are generated both near the surface of the outer surface of the heated body and near the surface of the end surface of the heated body, and the amount of heat generated at the end becomes larger than at other parts. This is because this phenomenon is called the edge effect.

As a means for solving the excessive heating of the end portion due to the edge effect, Patent Document 1 discloses a means of disposing a conductive auxiliary base material at the end portion of the object to be heated. Further, Patent Document 2 discloses means for interposing a heat insulating member between the auxiliary base material and the object to be heated in order to suppress the influence of heat generation of the auxiliary base material on the temperature uniformity of the object to be heated. ing.

JP, 2014-56197, A JP, 2018-32511, A

When the outer diameter of the object to be heated is smaller than the outer diameter of the auxiliary substrate, the magnetic flux density in the vicinity of the end of the object to be heated becomes smaller because more eddy current flows in the auxiliary substrate than the object to be heated, The temperature of the end of the heated object becomes low. At that time, the temperature uniformity of the object to be heated can be maintained by increasing the magnetic flux density near the end of the object to be heated by separating the distance between the auxiliary base material and the object to be heated. In the induction heating method described in Patent Document 2, it is possible to increase the distance between the auxiliary base material and the object to be heated by increasing the thickness of the heat insulating member, but in continuous production, there is a problem of heat storage of the heat insulating member. appear. In continuous production, in order to stably realize temperature uniformity of the object to be heated, it is necessary to suppress the heat insulating material in contact with the object to be heated within a predetermined temperature range. However, especially when the heating temperature of the object to be heated is high and the production is performed in a short cycle time, the heat insulating member heated by heat conduction from the object to be heated during heating the object to be heated is not heated until the next object to be heated. It is difficult to recover the initial temperature during, and gradually accumulate heat in continuous production. As a result, the heat insulating material exceeds a predetermined temperature, and the temperature uniformity of the object to be heated is reduced.
The present invention has been made in view of the above problems, and even if the outer diameter of the object to be heated is small or large, the object to be heated can be heated in a short cycle time without replacing the induction heating coil or the gripping mechanism. It is an object of the present invention to provide an induction heating device capable of heating uniformly.

An induction heating apparatus comprising: an induction heating coil in which a cylindrical object to be heated is disposed; and an auxiliary base material disposed inside the induction heating coil and generating an eddy current by the induction heating coil to generate heat. And
When the object to be heated is placed inside the induction heating coil, the object further includes a gripping member interposed between the object to be heated and the auxiliary base material to support the object to be heated,
The induction heating device is capable of supporting a first heated body and a second heated body having an outer diameter larger than that of the first heated body,
The gripping member is
The distance between the one end of the first object to be heated and the auxiliary base material when the first object is placed inside the induction heating coil is the second object to be heated by the induction heating. The object to be heated is supported so as to be longer than the distance between one end of the second object to be heated and the auxiliary base material when arranged inside the coil, and
It is made of non-magnetic material,
The contact portion of the gripping member with the object to be heated is made of a material whose thermal conductivity in the thickness direction is 1.0 W/(m·K) or less,
Induction heating, wherein the thermal conductivity from the contact portion of the gripping member with the object to be heated to the contact portion with the auxiliary base material is 3.5 W/(m·K) or more. A device is provided.

According to the present invention, it is possible to suppress the escape of heat from the object to be heated to the auxiliary base material while heating the object to be heated, and it is possible to uniformly heat the object to be heated. At the same time, since it is possible to suppress the heat storage of the gripping member even in the continuous production, it is possible to provide an induction heating device that stably ensures uniform heating of the object to be heated for a long period of time.

It is a figure which shows the apparatus outline|summary of the induction heating apparatus of this invention. It is a schematic diagram for demonstrating the principle of this invention. It is a sectional view of a grasping member concerning Example 1 of the present invention. It is a figure which shows the outline of a structure of the induction heating apparatus which concerns on a prior art. It is a top view and a sectional view of a grasping member concerning modification 1 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.
FIG. 1 is a diagram showing an outline of the induction heating apparatus of the present invention.

The spiral induction heating coil 100 is fixed by a coil supporting member 101 and attached to a pedestal 102. The induction heating coil 100 is connected to a high frequency power supply 104 via a matching unit 103. The high-frequency power source 104 is connected to the control unit 115, and heats the object 120 to be heated arranged inside the induction heating coil by passing a high-frequency current according to an output command from the control unit 115 to the induction heating coil 100. You can

The auxiliary base materials 111a and 111b are held by the bearing portions 112a and 112b, and attached to the elevating mechanisms 114a and 114b. The elevating mechanisms 114a and 114b are connected to the control unit 115 and can operate in response to a position movement command from the control unit. When arranging the heated body 120 inside the induction heating coil 100, the heated body 120 can be contact-held by sandwiching the heated body 120 with gripping members 110a and 110b connected to the auxiliary base materials 111a and 111b. Is. The gripping member 110a is interposed between the heated object 120 and the auxiliary base material 111a, and the gripping member 110b is interposed between the heated object 120 and the auxiliary base material 111b.

At least one of the gripping members 110a and 110b is connected to the rotating mechanism 113, and has a structure in which the heated object 120 gripped can be rotated. In the example shown in FIG. 1, the gripping member 110a is rotated by the rotating mechanism 113 together with the auxiliary base material 111a. Then, the heated body 120, the grip member 110b, and the auxiliary base material 111b are rotated by the auxiliary base material 111a. The rotational symmetry axis of the induction heating coil 100 and the rotational axis of the heated object 120 can be adjusted substantially coaxially by an adjusting mechanism (not shown).

FIG. 2 is a schematic diagram for explaining the principle of the present invention.
The length of the induction heating coil 100 (L in FIG. 2) is in a range in which eddy current is generated not only in the heated object 120 by flowing a high frequency current in the induction heating coil 100, but also in the auxiliary base materials 111a and 111b. Is the length.

The auxiliary base materials 111a and 111b are made of a conductive material. An eddy current flows through the auxiliary base materials 111a and 111b, and a magnetic field is generated in a direction in which the magnetic field generated by the induction heating coil 100 is weakened, thereby adjusting the magnetic flux density near the end of the heated object 120 and excess of the end. It is possible to suppress excessive heat generation. The vicinity of the end of the heated body 120 means the vicinity of the upper end of the heated body 120 (the vicinity of the end near the gripping member 110a) and the lower end of the heated body 120 (the end near the gripping member 110b). Neighborhood) is meant.

The auxiliary base materials 111a and 111b have a cylindrical shape or a cylindrical shape, and have the same diameter as the outer diameter of the heated body 120 or an outer diameter larger than the outer diameter of the heated body 120. That is, the auxiliary base materials 111a and 111b of the induction heating device according to the present invention have an outer diameter that is equal to or larger than the outer diameter of the heated object having the largest outer diameter.
The induction heating device according to the present invention can support the first heated object and the second heated object having an outer diameter larger than that of the first heated object.

The grip members 110a and 110b are made of at least two kinds of non-magnetic materials that do not generate heat. This is because it does not affect the magnetic field generated by the induction heating coil 100 and the auxiliary base materials 111a and 111b.

The outer shape of each of the gripping members 110a and 110b is such that the diameter of the gripping members 110a and 110b is reduced as the distance from the auxiliary base materials 111a and 111b increases. You can change the distance between and. When the outer diameter of the object 120 to be heated is smaller than the outer diameter of the auxiliary base materials 111a and 111b, the distance between the auxiliary base materials 111a and 111b and one end of the object 120 to be heated is increased, so that the object having the smaller outer diameter is This is to prevent the temperature in the vicinity of the end portion from decreasing even when the heating body is heated.

In order to stably adjust the magnetic flux density near the ends, the auxiliary base materials 111a and 111b are preferably made of a material having a relative magnetic permeability similar to that of the heated body 120. When the auxiliary base materials 111a and 111b have a cylindrical shape, the thickness of the auxiliary base materials 111a and 111b is preferably 5 times or more the skin depth of the auxiliary base materials 111a and 111b. The "thickness of the auxiliary base material" is {(outer diameter of the auxiliary base material-inner diameter of the auxiliary base material)/2}. The "skin depth" is the "depth at which the electromagnetic field incident on a certain substance is attenuated to 1/e (≈1/2.718)".

FIG. 3 is a cross-sectional view of gripping members 110a and 110b according to Example 1 described later. As shown in FIG. 3, the gripping member 110a according to the first embodiment is composed of two kinds of materials, a first member 150a and a second member 151a, and the gripping member 110b also includes the first member 150b and the second member 151a. The member 151b is made of two kinds of materials.
The first members 150a and 150b located on the side of the object to be heated are made of a material having a thermal conductivity in the thickness direction of 1.0 W/(m·K) or less.
In addition, the second member 151a located on the auxiliary base material side has a thermal conductivity from the contact portion of the first member 150a with the object to be heated to the contact portion with the auxiliary base material 111a between the materials. In consideration of the decrease in thermal conductivity at 3, the material should be 3.5 W/(m·K) or more.
Similarly, the second member 151b located on the auxiliary base material side has a thermal conductivity of 3.5 W from the contact portion of the first member 150b with the body to be heated to the contact portion with the auxiliary base material 111b. Use a material that exceeds /(m·K).

When the object to be heated is heated, the escape of heat from the object to be heated to the auxiliary base material is suppressed, and after heating, the temperature of the gripping member is quickly restored to a predetermined temperature, thereby heating with a uniform temperature distribution. This is because it is possible to realize continuously.
The numerical values shown in FIG. 3 indicate sizes when used in Examples described later, and these numerical values do not limit the technical scope of the present invention.

Since the auxiliary base materials 111a and 111b are also heated by induction heating together with the object to be heated, it hinders temperature recovery of the gripping member during continuous heating. Therefore, it is preferable that the auxiliary base materials 111a and 111b have a cooling mechanism and be controlled within a predetermined temperature range.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
<Example 1>
A continuous heating test was performed using the induction heating device shown in FIG.
Table 1 shows the outer diameter, the inner diameter, and the length of the object 120 to be heated used in this example. Although the present invention can be applied to a plurality of objects having a plurality of outer diameters, the kind of the object to be heated is selected so that the conditions for continuous heating become more severe.
The base layer of the body to be heated 120 is made of an aluminum alloy and has a relative magnetic permeability of about 1.0. A protective layer having a thickness of about 5.0 μm is formed on the outermost layer of the object to be heated 120.

As the induction heating coil 100, a linear 8 mm copper tube was bent to form a spiral shape. The induction heating coil 100 had a total length (L in FIG. 2) of 450 mm, an outer diameter (D in FIG. 2) of 88 mm, and a winding number of 23 turns. Cooling water was supplied to the inside of the copper tube for cooling. The induction heating coil 100 was fixed to a coil supporting member 101 made of bakelite.

The induction heating coil 100 was connected to a high frequency power source 104 via a matching unit 103. In addition, the temperature at the longitudinal center position of the object to be heated 120 is measured by a radiation thermometer (not shown), and the measured temperature is input to the control unit 115 to perform heating by feedback control.
The heating is performed by applying a high frequency current to the induction heating coil 100 by the high frequency power supply 104. The initial temperature was set to 23° C. and the target temperature was set to 117° C. in 10 seconds.

The auxiliary base materials 111a and 111b are made of an aluminum alloy, which is the same material as the base layer of the object 120 to be heated, and have a columnar shape with an outer diameter of 30 mm. This is approximately the same diameter as the heated body having the largest outer diameter among the heated bodies having a plurality of outer diameters. Further, the rotary joints 141a and 141b were connected to the auxiliary base materials 111a and 111b, and cooling water was supplied from the cooling water circulation mechanism 142 to perform cooling.

FIG. 3 shows cross-sectional shapes of the gripping members 110a and 110b. A channel 140 for circulating cooling water is provided inside the auxiliary base material. The contact portion with the object 120 to be heated has a tapered shape in which the diameter is reduced as the distance from the auxiliary base materials 111a and 111b increases. When the gripping members 110a and 110b contact and grip the object 120 to be heated, the distance between one end of the object 120 to be heated and the auxiliary base materials 111a and 111b is set to the value shown in Table 1 obtained by performing a heating experiment in advance. .. "The distance between one end of the heated body 120 and the auxiliary base materials 111a and 111b" means "the distance between the upper end of the heated body 120 and the lower end of the auxiliary base material 111a" and "the lower end of the heated body 120 and the auxiliary base". “Distance from the upper end of the material 111b”.

The gripping members 110a and 110b are formed by laminating two kinds of materials.
As the first member 150 on the heated body 120 side, a PEEK (polyetheretherketone) material having a thermal conductivity of 0.9 W/(m·K) was used.
That is, as shown in Table 1, the contact portion of the gripping member with the object to be heated has a thermal conductivity in the thickness direction of 0.9 W/(m·K).
As the second member 151 on the side of the auxiliary base materials 111a and 111b, aluminum nitride having a thermal conductivity of 160 W/(m·K) was used.
That is, the order of materials from the auxiliary base material to the first member is as follows.
・Aluminum alloy (auxiliary substrate 111)
-Aluminum nitride (second member 151)
・PEEK (first member 150)
Further, in order to suppress a decrease in heat transfer due to a minute air layer between PEEK and aluminum nitride or between aluminum nitride and the auxiliary base material, the following epoxy adhesive is filled between the respective parts. Then, the auxiliary base materials 111a and 111b were fixed with bolts (not shown).
-Epoxy adhesive Araldite (registered trademark) manufactured by Huntsman Advanced Materials Co., Ltd. Thus, an adhesive layer was formed between the first member and the second member.

The material of the gripping members 110a and 110b on the heated body 120 side must be softer than the aluminum alloy of the base layer of the heated body 120 so as not to damage the heated body 120. In the present embodiment, by using a PEEK material that is softer than an aluminum alloy, it is possible to achieve both suppression of scratches on the heated object 120 and realization of desired thermal conductivity.

The thermal conductivity from the contact portion of the gripping member 110a and the gripping member 110b that contacts the heated object 120 to the auxiliary base materials 111a and 111b, which are configured by the above-described members, is generally known as a method for measuring the thermal conductivity. It was calculated using a known heat flow meter method. The heat flow meter method is a method of calculating the thermal conductivity by measuring the temperature gradient of a sample whose thermal conductivity is desired to be measured, one side being high temperature and the other side being low temperature. In this example, the measurement was performed by reproducing a measurement configuration close to the configuration of this example. The measurement configuration and measurement results are shown below.

The measurement configuration was such that the low temperature source was a cooling block through which cooling water was passed and the high temperature source was a heating block with a built-in heater. Then, from the low temperature side to the high temperature side, a total of 5 parts were laminated in the order of aluminum alloy, aluminum nitride and PEEK so as to have the same structure as that of the present embodiment. That is, the order of materials in the measurement configuration is as follows.
・Cooling block (low temperature side)
・Aluminum alloy・Aluminum nitride・PEEK
・Heating block (high temperature side)

In order to measure the temperature gradient, thermocouples were installed at three locations between the cooling block and the aluminum alloy, between the aluminum alloy and aluminum nitride, and between the PEEK and the heating block. Further, an epoxy adhesive Araldite (registered trademark) was filled between the aluminum alloy-aluminum nitride and between the aluminum nitride-PEEK, and the cooling block and the heating block were sandwiched from both sides and fixed by pressure welding. All five parts had a square shape of 100 mm in length and 100 mm in width, and the thickness was 5 mm for the cooling block, aluminum alloy, and heating block, 7 mm for aluminum nitride, and 2 mm for PEEK. Further, the outer periphery of the five parts was covered with a heat insulating material to suppress heat exchange between parts other than each part.
Based on this configuration, the calculated thermal conductivity from the PEEK surface on the heating block side to the aluminum nitride surface on the aluminum alloy side is calculated from the contact portion of the holding member 110a with the heated body 120 to the contact portion of the auxiliary base material 111a. It shows the thermal conductivity up to.
Similarly, the calculated thermal conductivity indicates the thermal conductivity from the contact portion of the holding member 110b with the heated body 120 to the contact portion with the auxiliary base material 111b.

Based on the above measurement configuration, the thermocouple values between the respective parts were measured when the cooling block was set to 25° C. with cooling water and the heating block was set to 120° C. with a heater. The results are shown below.
・Temperature between cooling block and aluminum alloy: 26℃
・Temperature between aluminum alloy and aluminum nitride: 27.5℃
・PEEK-heating block temperature: 119℃
The amount of heat passing through the aluminum alloy matches the amount of heat passing through the aluminum nitride and PEEK, and the thermal conductivity of the aluminum alloy is known.
Therefore, the thermal conductivity from the PEEK surface on the heating block side (the contact portion of the gripping member with the heated body) to the aluminum nitride surface on the aluminum alloy side (the contact portion of the gripping member with the auxiliary base material) is calculated. it can. As a result of the calculation, the thermal conductivity was 3.5 W/(m·K).
That is, as shown in Table 1, the thermal conductivity from the contact portion of the gripping member with the body to be heated to the contact portion with the auxiliary base material is 3.5 W/(m·K).

The auxiliary base material 111a was held by the bearing portion 112a, and the bearing portion 112a was attached to the elevating mechanism 114a. The auxiliary base material 111b was held by the bearing 112b, and the bearing 112b was attached to the elevating mechanism 114b. The elevating mechanisms 114a and 114b are configured by a single-axis robot and a controller, are connected to a control unit 115 configured by a PLC (Programmable Logic Controller), and position of each operation according to a position movement command from the control unit 115. Allowed to move to coordinates.

The vertical position of the heated object 120 is controlled by the raised position of the elevating mechanism 114b. The object 120 to be heated is placed inside the induction heating coil 100 by lowering the elevating mechanism 114b, placing the object 120 to be heated on the gripping member 110b, and then elevating the object elevating mechanism 114b.

A pressing mechanism (not shown) having a spring was provided between the elevating mechanism 114a and the bearing 112a. The position of the lifting mechanism 114a is determined according to the raised position of the lifting mechanism 114b and the length of the heated object 120. In this embodiment, the ascending position of the elevating mechanism 114b is the position where the longitudinal center of the object 120 to be heated and the longitudinal center of the induction heating coil 100 coincide with each other, and the elevating mechanism 114a is located at the position to be heated. The position where 120 can be sandwiched by the force of 10 to 20 N is set.

At least one of the gripping members 110a and 110b is connected to the rotating mechanism 113, and the heated object 120 gripped has a rotatable structure, and the rotation speed is set to about 100 rpm.
Since the gripping members 110a and 110b and the heated object 120 are pressed with a force of 10 to 20 N, the gripping members 110a and 110b and the heated object 120 can rotate at the same speed without slipping. By rotating the heated body 120 during heating, it is possible to suppress temperature unevenness in the circumferential direction of the heated body.

A thermoviewer was used to measure the temperature of the object to be heated 120 and the gripping members 110a and 110b after heating.

Next, the procedure of the continuous heating experiment performed in Example 1 will be described.
First, the object 120 to be heated is placed on the gripping member 111b with the elevating mechanism 114b being lowered. After that, the elevating mechanism 114b is raised, the object to be heated is inserted into the induction heating coil 100, and the object to be heated 120 is sandwiched between the gripping members 110a and 110b from above and below.

When the grasping of the heated body 120 is completed, rotation and heating of the heated body 120 are started.
After about 10 seconds, when the longitudinal center temperature of the object to be heated 120 reaches the target temperature of 117° C., heating and rotation are stopped.

After heating and rotation are stopped, the object 120 to be heated is lowered below the induction heating coil 100 by the elevating mechanism 114b, and the object 120 to be heated is taken out.

This procedure was repeated 10 cycles with a cycle time of 14 seconds.

Table 2 shows the transition of the following temperature and the transition of the temperature difference after the heating, which was measured by a thermoviewer.
-Surface temperature of the gripping member 110a-Temperature of the central part of the heated object 120 (longitudinal center position of the heated object 120)-Upper temperature (position 10 mm below the upper end of the heated object 120)-Central part and upper part The temperature change of the gripping member 110a was extremely small, and the temperature change of the upper part of the object to be heated was 1° C. or less.
In this experiment, the structure is vertically symmetrical, the surface temperature of the gripping member 110b is the same as the surface temperature of the gripping member 110a, and the temperature of the lower part of the heated object 120 is the upper temperature of the heated object 120. Was the same as Therefore, the description of the surface temperature of the grip member 110b and the temperature of the lower portion of the heated object 120 is omitted.
In addition, in the present embodiment, the contact portions of the gripping members 110a and 110b with the object 120 to be heated are tapered all around. When it is desired to suppress heat transfer between the heated body 120 and the gripping members 110a and 110b when heating the heated body 120, unevenness or a groove is formed on the contact surface of the gripping members 110a and 110b with the heated body 120. Alternatively, the contact area with the heated object 120 may be reduced.

FIG. 5 shows a plan view and a sectional view of the holding member according to the first modification. FIG. 5 shows an example of unevenness formed on the contact surface of the gripping member 110b with the heated object 120 in order to reduce the contact area between the gripping member and the heated object. The heated object 120 is not shown in FIG.
FIG. 5 is an example in which convex portions 501b and concave portions 502b having substantially the same shape and size are provided radially and alternately on the side surface of the truncated cone-shaped gripping member 110b. When the contact surface of the gripping member 110b with the heated object 120 has an uneven shape as shown in FIG. 5, the convex portion 501b contacts the heated object 120, but the recessed portion 502b does not contact the heated object 120. .. Therefore, the contact area between the gripping member 110b and the body 120 to be heated is reduced to almost half the contact area when the projections 501b and the recesses 502b are not formed on the gripping member 110b.

<Comparative example>
Using the gripping member shown in FIG. 4, the same heating test as in Example 1 was performed.
The gripping members 410a and 410b shown in FIG. 4 are made of PEEK bulk and have the same outer shape as the gripping members 110a and 110b used in the first embodiment. The same conditions as in Example 1 were used except that the gripping member 410a was used instead of the gripping member 110a, and the gripping member 410b was used instead of the gripping member 110b.

Table 3 shows the transition of the following temperature and the transition of the temperature difference after the heating, which was measured by the thermoviewer.
-Surface temperature of the gripping member 410a-Temperature of the central part of the heated object 120 (longitudinal center position of the heated object 120)-Upper temperature (position 10 mm below the upper end of the heated object 120)-Central part and upper part The temperature difference between the gripping members 410a and 410b was large, and the temperature difference between the objects to be heated 120 was 2.5°C.

100 Induction heating coil 101 Coil support member 102 Coil pedestal 103 Matching device 104 High frequency power supply 110 Gripping member 111 Auxiliary base material 112 Bearing 113 Rotating mechanism 114 Elevating mechanism 115 Control part 120 Heated object 130 Position adjusting means 140 Cooling water circulation flow path 141 rotary joint 142 cooling water circulation mechanism 150 first member 151 second member 210 information storage unit

Claims (4)

An induction heating apparatus comprising: an induction heating coil in which a cylindrical object to be heated is disposed; and an auxiliary base material disposed inside the induction heating coil and generating an eddy current by the induction heating coil to generate heat. And
When the object to be heated is placed inside the induction heating coil, the object further includes a gripping member interposed between the object to be heated and the auxiliary base material to support the object to be heated,
The induction heating device is capable of supporting a first heated body and a second heated body having an outer diameter larger than that of the first heated body,
The gripping member is
The distance between the one end of the first object to be heated and the auxiliary base material when the first object is placed inside the induction heating coil is the second object to be heated by the induction heating. The object to be heated is supported so as to be longer than the distance between one end of the second object to be heated and the auxiliary base material when arranged inside the coil, and
It is made of non-magnetic material,
The contact portion of the gripping member with the object to be heated is made of a material whose thermal conductivity in the thickness direction is 1.0 W/(m·K) or less,
Induction heating, wherein the thermal conductivity from the contact portion of the gripping member with the object to be heated to the contact portion with the auxiliary base material is 3.5 W/(m·K) or more. apparatus. The gripping member includes a first member that constitutes a contact portion of the object to be heated, and a second member that is located closer to the auxiliary base material side than the first member,
The first member is made of polyetheretherketone (PEEK),
The induction heating device according to claim 1, wherein the second member is made of aluminum nitride. The induction heating device according to claim 2, further comprising an adhesive layer between the first member and the second member. The induction heating device according to claim 3, wherein the adhesive layer is made of an epoxy adhesive.