JPH0218557Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Use This invention relates to a heater used for removing fittings such as gears and bearings that are tightly shrink-fitted to a shaft.

Prior Art Removing a gear or the like that is firmly attached to a shaft is a relatively troublesome job, and the work is usually done by heating and enlarging the inner diameter of the gear or the like that is fitted. Direct flame type heaters such as gas burners are also used as heaters in this case, but induction heaters that use electromagnetic induction are superior because there is no risk of igniting others.

As shown in FIG. 1, a conventional induction heater 1 of this type has only an excitation coil 2 as a functional part and does not have any special members such as a core. The excitation coil 2 is wound into a ring with a hole formed in the center, and is normally housed in a case. To use the heater 1, as shown in Fig. 1, the heater 1 is fitted from one side onto the shaft 4 on which the gear 3 is fitted, and brought into contact with the gear 3, and the excitation coil 2 is connected from the terminal. Apply high frequency current to. Then, a magnetic field having a distribution of magnetic lines of force 5 as shown by thin lines in the figure is generated. Since this magnetic field is alternating, the metal gear 3 is rapidly heated by Joule heat due to the eddy currents induced inside. That is, the inner diameter of the gear 3 increases due to thermal expansion due to heating, and the gear 3 becomes easier to remove.

However, in this conventional induction heater, the distribution of magnetic lines of force 5 is somewhat diffused as shown in Figure 1, and the shaft 4 is heated to the same extent as the gear 3, and the inner diameter of the gear 3 expands and expands. However, there were times when it was difficult to remove gear 3.

Problems to be Solved by the Invention The object of the present invention is to provide an improved induction heater so that the magnetic circuit generated by the excitation coil 2 intensively reaches the stuck object, that is, the gear to be removed.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2, the symbol 6 indicates the induction heater of the present invention, and its main functional parts are an excitation coil 7 and a core 8. The excitation coil 7 is wound around the core 8 in multiple layers in the circumferential direction thereof, and is formed into an annular shape. Sufficient heat-resistant insulation is provided between the coils and between the coil and the core 8 to form a heat insulating layer 9.

The core 8 is made of a magnetically conductive material such as iron or ferrite, and is usually formed in the shape of a ring or a short tube and has a slit 10 (FIG. 4) in the axial direction.
A heat insulating layer 11 is provided on the inner periphery. The cross-sectional shape of the core 8 is determined by the cross-section of the shaft 4 through which it needs to be inserted.

Although only the main functional part is shown in FIG. 2, the main functional part of the heater as a whole is housed in a case 12 as shown in FIG. Symbol 13 is a terminal section (outlet) that connects the external power supply and excitation coil 7
It is.

Now, when the highly conductive core 8 is interposed between the excitation coil 7 and the shaft 4 and put into operation as in the case of FIG. 1, the core 8 becomes part of a magnetic circuit with almost no resistance. The magnetic lines of force 11 (thin wires) generated by the excitation coil 7 directly and intensively reach the fitted object (gear 3) without being diffused elsewhere or bypassing the shaft 4. Moreover, since the reaching point is the inner diameter portion of the gear 3, this portion is rapidly heated. Furthermore, since the proportion of the shaft 4 that is heated by the alternating magnetic field is extremely small, the enlargement of the inner diameter becomes substantial and the heating efficiency is improved.

In addition, in this case, the heat generation in the core 8 due to iron loss is
The heat is suppressed by the axial slit 10 provided in the core 8, and even the slightest amount of heat generated is not transmitted to the shaft 4 by the heat insulating layer 11 on the inner periphery of the core. Since the heat insulating layers 10 and 9 are formed on the inner and outer peripheral surfaces of the core 8, the heat generated in the core 8 is transferred to the core 8.
The heat is conducted to the gear 3 from the end face of the gear 3 and is effectively used for heating the gear 3.

The core 8 may be removable or replaceable with respect to the excitation coil 7, or the core 8 may have a shape other than a ring or short tube with a hole in the center, such as a semicircle or a U-shape. be.

As described above, according to the present invention, the magnetic circuit of the excitation coil is regulated by the core so that the lines of magnetic force of the generated magnetic field are concentrated on the inner diameter of the fitted object (gear), and the heat generated in the core itself is reduced. By suppressing and effectively utilizing the slight amount of heat generation that cannot be avoided, the object to be heated by the excitation coil can be heated extremely efficiently.

[Brief explanation of the drawing]

Figure 1 is a sectional view for explaining the conventional example, Figure 2 is a sectional view for explaining the conventional example;
The figure is a sectional view for explaining the present invention, FIG. 3 is a perspective view showing an example of the external appearance of the induction heater, and FIG. 4 is a perspective view of the core. 6: induction heater, 7: excitation coil, 8: core,
10: Slit, 9, 11: Heat insulation layer.

Claims (1)

[Claims for Utility Model Registration] (1) An excitation coil is wound circumferentially around the outer periphery of a ring or short tubular core made of a good magnetic conductor and has slits formed in the axial direction, and the inner periphery of the core is insulated. An induction heater for a fitted article, which is formed by providing a layer and connecting the excitation coil to a high frequency power source. (2) The induction heater according to claim 1 of the utility model registration, wherein the core has a heat insulating layer on its outer peripheral surface and inner peripheral surface. (3) Utility model registration claim 1, characterized in that the core has a slit formed in the axial direction.
Induction heater as described in Section.