JP3613950B2 - Inductor for induction heating - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating inductor, and more particularly, to an induction heating inductor having excellent heat resistance and a structure for blocking radiant heat from a material to be heated.
[0002]
[Prior art]
For example, the outer ring (cylinder) is expanded by heating at a high temperature, and the outer ring (cylinder) is fitted to the inner ring (cylinder) or shaft and contracted by cooling to room temperature to obtain a strong bond between the two. Processing is known. In this shrink fitting process, induction heating is used to heat the outer ring (cylinder), which is a material to be heated, at a high temperature.
[0003]
As already known, induction heating generates an alternating magnetic field by passing an alternating current through a coil, and heats the heated material by eddy current loss and hysteresis loss generated in the heated material placed in the alternating magnetic field. It is something to be made. Induction heating includes low-frequency induction heating using a current of 50/60 Hz and high-frequency induction heating using a current higher than this, depending on the material to be heated.
[0004]
FIG. 3 is a main part structural diagram for explaining a conventional low-frequency induction heating coil, FIG. 4 is a main part structural diagram for explaining a conventional inductor, and FIG. It is a graph explaining the relationship of fitting temperature.
In FIG. 3, 8 is a double glass copper wire, 9 is a glass cloth tape, and these are vacuum-impregnated. In FIG. 4, 6 is an iron core, 7 is a material to be heated (workpiece), 10 is a heating coil assembly, and H is radiant heat. Further, in FIG. 5, the horizontal axis represents the shrinkage allowance (μm), and the vertical axis represents the shrinkage fitting temperature (° C.).
[0005]
As shown in FIG. 3, the conventional low-frequency induction heating coil is, for example, a double glass-wound copper wire 8 wound in a cylindrical shape with a predetermined dimension, and then wound into a spiral with a glass cloth tape 9 and fixed. It has a structure in which the entire coil is fixed by a vacuum impregnation treatment with an F-type varnish or the like.
In this low frequency induction heating coil, the heating coil can be made small because the coil can be arranged close to the material to be heated due to its structure, but the heating coil is radiated from the surface of the material 7 to be heated as shown in FIG. As assembly 10 is heated, the temperature rises. Further, when the heating temperature of the material to be heated 7 becomes high, the temperature of the heating coil assembly 10 exceeds the heat resistance temperature of the heating coil insulating film due to the radiant heat H from the material 7 to be heated, the insulating film burns out, and the heating coil There is a risk that it will become unusable.
[0006]
Thus, since the heat resistant temperatures of the low-frequency induction heating coil, such as the double glass-wrapped copper wire 8, the glass cloth tape 9, and the F-type varnish impregnation treatment, are low, the conventional low-frequency induction heating coil is as shown in FIG. In general, the shrink fitting temperature is about 300 ° C. or less.
However, recently, in order to improve the quality of products such as shrink fit strength, products that have a large allowance for shrink fit have increased. Therefore, it is necessary to increase the shrink fitting temperature so as to be about 500 ° C. or higher, and it is necessary to improve the heat resistance of the low frequency induction heating coil.
[0007]
[Problems to be solved by the invention]
As described above, in shrink fitting, in order to improve the quality of products such as shrink fitting strength, if a large shrinkage allowance is required, it is necessary to increase the shrink fitting temperature as shown in FIG. However, in the current low-frequency induction heating coil, the heating coil may be burned by radiant heat from the material to be heated, and it is actually difficult to use it as a heating coil for production equipment.
[0008]
As a countermeasure, there is a method of using a ceramic copper wire excellent in heat resistance, but even if the heat resistance of the ceramic copper wire itself is improved, a glass cloth tape for fixing the heating coil, F-type varnish, etc. Due to a problem with the heat-resistant temperature, it has been difficult to use as a heating coil for production equipment.
Accordingly, an object of the present invention is to provide an induction heating coil that is excellent in heat resistance and resistant to radiant heat. Specifically, it is to provide a low-frequency induction heating coil that can improve the heat-resistant temperature of the low-frequency induction heating coil and improve the shrink-fitting processing quality, and the heating temperature of the material to be heated is 500 °. An object of the present invention is to provide a low-frequency induction heating coil capable of induction heating without burning the insulating film of the coil even at a high temperature of C or higher.
[0009]
[Means for Solving the Problems]
According to the invention of claim 1 , in an induction heating inductor for heating a material to be heated which is an outer ring for shrink fitting by induction heating in order to obtain a bond with an inner ring, the induction heating inductor has heat resistance and heat. reportedly hard material, by winding a ceramic insulating coating copper wire, especially to a ceramic bobbin, since it is configured induction heating coil containing a material to be heated inside the ceramic bobbin, radiant heat from the material to be heated that is heated ceramic Since the copper wire is not directly heated by being blocked by the bobbin, it is possible to prevent the copper wire from reaching a high temperature.
Moreover, the temperature of a to-be-heated material can be 500 degreeC or more by making the insulating film of a copper wire into a ceramic.
[0010]
According to the invention of claim 2, the copper wire can be easily wound around the bobbin by providing the collar portion on the cylindrical ceramic bobbin.
Further, since the induction heating is intermittently used, by cooling the inner surface of the ceramic bobbin when not in use, it is possible to suppress the temperature rise of the induction heating coil, it is possible to extend the results coil life .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a main part structural diagram for explaining a low frequency induction heating coil as one embodiment of the present invention, in which the right side is a cross section and the left side is an external view. FIG. 2 is a main part structural diagram for explaining the inductor for low frequency induction heating according to the present invention.
In FIG. 1, 1 is a low-frequency induction heating coil, and 2 is a ceramic bobbin made of a ceramic core. As shown in the drawing, the cross section has a U shape and has a collar portion 2 '. 3 is a glass cloth tape having heat resistance and insulation for fixing and holding the copper wire 4, and 4 is a ceramic insulating coated copper wire in which the insulating coating is made of ceramics.
[0012]
In FIG. 2, 5 is an inductor, 6 is an iron core through which magnetic flux generated from a heating coil passes, and 7 is a material to be heated (workpiece). H indicates radiant heat radiated from the material 7 to be heated.
In such a configuration, a ceramic insulating coated copper wire 4 having a high softening temperature, for example, a softening temperature of 500 ° C. or more, is attached to the outer peripheral portion of the cylindrical portion of the ceramic core 2 which is a bobbin having a flange portion 2 ′. The ceramic insulating coated copper wire 4 is fixed and held on the ceramic core 2 by winding the outer periphery of the ceramic insulating coated copper wire 4 with the glass cloth tape 3 after winding up around the letter-shaped cylindrical portion many times. The low frequency induction heating coil 1 is completed by the above steps. Further, the completed heating coil 1 is incorporated into the iron core 6 as shown in FIG.
[0013]
In order to perform induction heating, first, the material to be heated 7 is positioned, and a low-frequency current is passed through the ceramic insulating coated copper wire 4 to generate an induced current inside the material to be heated 7. The material 7 is heated.
Radiant heat H is radiated from the surface of the heated material 7 heated to a high temperature of 500 ° C. or higher toward the heating coil as indicated by the dotted line. The radiant heat H is blocked (and absorbed and radiated) by the ceramic core 2 and further attenuated and uniformized. As a result, the overall temperature rise and local temperature rise of the ceramic insulating coated copper wire 4 can be suppressed, and thermal damage can be reduced. Therefore, the heated material 7 can be heated to a high temperature (that is, the shrink fitting temperature can be increased to 300 ° C. or higher), and the product quality such as shrink fitting strength can be improved.
[0014]
Thereby, the induction heating coil 1 can be prevented from being used beyond the heat resistance temperature of the insulating coating by the radiant heat H from the material 7 to be heated.
In the present embodiment, the ceramic bobbin has been described. However, the same effect can be obtained with other members having heat resistance and heat non-conductivity.
Moreover, it is also possible to use the conventional double glass winding copper wire by considering the shape (thickness etc.) of the ceramic core 2 and an appropriate cooling method.
[0015]
Moreover, since the ceramic core 2 is heated by the radiant heat H, it can prevent that the whole becomes high temperature by cooling a bobbin.
Furthermore, although the low-frequency induction heating has been described in the present embodiment, it can be applied to high-frequency induction heating with a small number of copper wire windings.
[Brief description of the drawings]
FIG. 1 is a main part structural diagram for explaining a low-frequency induction heating coil as one embodiment of the present invention.
FIG. 2 is a structural diagram of a main part for explaining an inductor for low-frequency induction heating according to the present invention.
FIG. 3 is a main part structural diagram for explaining a conventional low frequency induction heating coil;
FIG. 4 is a structural diagram of a main part for explaining a conventional inductor.
FIG. 5 is a graph for explaining the relationship between shrink fitting temperature and shrink fitting allowance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Induction heating coil 2 ... Ceramic bobbin 3 ... Glass cloth tape 4 ... Ceramic insulation coating copper wire 5 ... Inductor 6 ... Iron core 7 ... Heated material 8 ... Double glass copper wire 9 ... Glass cloth tape 10 ... Heating coil Assembly H ... Radiant heat

Claims (3)

In an induction heating inductor that has at least an induction heating coil and an iron core that wraps the induction heating coil, and heats a material to be heated that is an outer ring for shrink fitting by induction heating in order to obtain a bond with the inner ring . ,
Comprising a non-conductive member of the heat having arranged heat resistance between the said induction heating coil the material to be heated,
The non-conductive member is a ceramic bobbin,
The induction heating coil includes at least a copper wire wound around an outer periphery of the ceramic bobbin, and a heat-resistant and insulating tape wound around the copper wire and fixing and holding the wound copper wire. ,
The copper wire is a ceramic insulating coated copper wire,
The induction heating inductor, wherein the material to be heated is accommodated inside the ceramic bobbin . The induction heating inductor according to claim 1, wherein the ceramic bobbin is cylindrical and has flanges at both ends. The induction heating inductor according to claim 1, wherein the induction heating coil is a low frequency induction heating coil.

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