JPH0620764A - Heater in induction heating system - Google Patents

Abstract

PURPOSE:To provide a heater of electromagnetic induction type capable of preventing over-heating which might cause remarkable drop of the lifetime of a ring-shaped object to be heated such as a bearing. CONSTITUTION:A magnetic circuit is formed from a body 1, a body core upper part 2 and a body core lower part 10 protruding from the body 1, and a rod- shaped core 3 to make communication of them like a bridge. A temp. sensor 6 is installed in a specified position on a ring-shaped object to be heated 21 such as a bearing which is mounted on a core guide cover 4 and threaded through the rod-shaped core 3, and a holding pressure for the object heated 21 is given to the temp. sensor 6 by a holding device 34 fixed to the core 3 so as to generate holding in a specified position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type heater for induction heating an annular object to be heated such as a bearing.

[0002]

2. Description of the Related Art Generally, when a bearing is mounted on a shaft in an interference fit state, the bearing is kept at about 80
Heating to a temperature as high as ℃ is performed. Since the bearing expands due to heat, it can be smoothly incorporated into the shaft without applying excessive force or impact, and it does not damage the shaft or the bearing. As a method of heating the bearing, there are a method of putting oil with a high flash point in an oil bath to make a hot water bath, a method of using a hot plate, etc., but it is possible to uniformly heat in a short time without using fire or oil, It is known to use an induction heating type heater which can perform work efficiently, safely and cleanly, and is small and easy to handle.

The induction heating type heater applies an alternating current of a commercial frequency to an exciting coil to generate an alternating magnetic flux in a bearing or the like which is an object to be heated by an electromagnetic induction action to flow an eddy current, and the object to be heated itself. Resistance is used to generate heat, and demagnetization is performed after heating to remove residual magnetism.

FIG. 10 is a perspective view of an induction heating type heater known as a conventional bearing heater, in which a main body core upper portion 2 and a main body core lower portion 10 project vertically from the main body 1 in the same direction, The main body core upper part 2 and the main body core lower part 10 are connected by a magnetic material inside the main body 1,
A magnetic closed circuit is formed by contacting a removable rod-shaped core 3 on the protruding ends of the upper main body core 2 and the lower main body core 10. An exciting coil (not shown) is wound around the magnetic body of the main body 1 in this magnetic circuit. The bearing 5, which is an annular object to be heated, is composed of a core guide cover 4 and a main body core lower portion 10 which are formed by penetrating the rod-shaped core 3 through an inner diameter hole and joined to the bottom of the protruding side end of the main body core lower portion 10 by a hinge not shown. It is held on a series of holding tables.
When not in use, the core guide cover 4 removes the rod-shaped core 3 and raises the bar-shaped core 3 upward so that the ends of the main body core upper part 2 and the lower part 10 are housed in the inner groove 22 of the core guide cover 4. Further, the main body 1 is provided with an operation switch 9 and a temperature sensor outlet 8, and the temperature sensor 6 is connected from the temperature sensor outlet 8 via a compensation lead wire 7. As shown in FIG. 11 which is an enlarged perspective view, the temperature sensor 6 is configured to have a detection end 11 formed of a thermocouple and an attraction magnet 12 for holding the bearing 5 in contact with it.

When the bearing 5 is heated, the core guide cover 4 is opened and tilted substantially horizontally to lower the main body core 10.
Together with the bearing 5 as a holding base, the bearing 5 is placed thereon, and both ends of the rod-shaped core 3 penetrating through the inner diameter hole of the bearing 5 are brought into contact with the projecting side ends of the main body core upper portion 2 and the main body core lower portion 10. Form a closed circuit. Next, the temperature sensor 6 is attached by the attraction magnet 12 so that the detection end 11 thereof contacts the inner ring of the bearing 5. After that, the operation switch 9 is operated to apply an exciting current to the exciting coil inside the main body 1, the bearing 5 is heated by electromagnetic induction, and the current is automatically detected when the temperature sensor 6 detects that the temperature has reached a preset temperature. Shut off.

When the bearing 21, which is an annular heated body, is smaller than the holding base of the core guide cover 4, FIG.
As shown in FIG. 5, an annular auxiliary base 23, which is sufficiently large with respect to the core guide cover 4 and is made of a heat-resistant non-magnetic insulating material such as a phenol laminated plate, is provided between the bearing 21 and the core guide cover 4, It is possible to prevent 21 from falling into the inner groove 22 of the core guide cover 4.

[0007]

However, in general, when a bearing is exposed to a temperature of 120 ° C. or more for a short time, its hardness is lowered and the life of the bearing is shortened remarkably, so that overheating is prevented. In addition, it is necessary to mount a temperature sensor on the annular heated body, detect the temperature of the inner ring of the annular heated body and set and limit the maximum heating temperature so as not to heat more than necessary. In the induction heating type heater, in particular, when the bearing of the annular object to be heated has a small diameter and is small as shown in FIG. 12, the mounting of the temperature sensor on the bearing becomes unstable, and the induced vibration caused by electromagnetic induction at the time of heating. Causes the bearing to move slightly on the annular auxiliary base, and the temperature sensor is disengaged from the inner ring of the bearing,
It may not be possible to accurately measure the temperature of the annular object to be heated, and heating may be carried out more than necessary to reduce the hardness, resulting in a marked decrease in the life of the bearing.

It is an object of the present invention to provide an electromagnetic induction type heater which can prevent overheating which significantly shortens the life of an annular heated object such as a bearing.

[0009]

In order to achieve the above object, the present invention has a magnetic circuit in which an exciting coil is wound, having a removable rod-shaped core penetrating an inner hole of an annular heated body, It consists of a holding base for the annular heated body, an alternating current of a commercial frequency is passed through the exciting coil, an alternating magnetic flux is generated in the annular heated body by an electromagnetic induction action, and an eddy current is passed through the annular heated body. In an induction heating type heater for generating heat, a temperature sensor that detects the temperature of a predetermined position of the annular heated body and controls energization to the exciting coil,
A holding device for pressing and holding the temperature sensor against the annular heated body is provided.

[0010]

Since the induction heating type heater according to the present invention is configured as described above, the temperature sensor can be pressed and held at a predetermined position of the annular heated body by the holding device, and induced vibration due to electromagnetic induction during heating. Therefore, the temperature sensor does not move slightly from the predetermined position due to the ring-shaped object to be slightly moved on the holding table such as the ring-shaped auxiliary table or the core guide cover, and the temperature sensor can accurately measure the ring-shaped object. Temperature can be measured to prevent overheating.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an induction heating type heater according to an embodiment of the present invention. Components equivalent to those of the conventional example shown in FIG. The temperature sensor 6 arranged at a predetermined position on the annular heated body 21 has a rod-shaped core 24.
It is held by a holding device 34 attached to the. The holding device 34 is made of a non-magnetic material or an insulating material to prevent unnecessary induction heating to this portion, and FIG. 2 and FIG. As shown in FIG. 3, a spring-like member having a curved portion 35 formed on a part thereof so as to generate a pressing force is provided, and a mounting elongated hole 37 is provided in a mounting portion 36 having one end thereof raised. The other end contacts the surface of the temperature sensor 6 with a spring force. As shown in FIG. 4 which is an enlarged front view of the main part of FIG. It is attached using the attachment nut 39. On the other hand, the temperature sensor 6 is configured such that the detection end 11 is brought into contact with the inner ring of the annular heated body 21, and then the holding device 34 is provided.
The temperature sensor 6 is elastically held by its free end, and the compensating lead wire 7 of the temperature sensor 6 is connected to the temperature sensor outlet 8 of the main body 1 as shown in FIG.

In this way, by holding the temperature sensor 6 while pressing it at a predetermined position on the annular heated body 21 by the holding device 34, the annular heated body 21 is induced to vibrate by electromagnetic induction during heating. By the core guide cover 4
The temperature sensor 6 is prevented from moving from a predetermined position of the ring-shaped heated body 21 as in the conventional case even if an attempt is made to make a slight movement on the holding base constituted by the main body core lower part 10 and the ring-shaped body 21, and the temperature sensor 6 does not move accurately. It is possible to prevent overheating by measuring the temperature of the object to be heated 21 and controlling the energization of the exciting coil when the temperature reaches a predetermined temperature.

FIG. 5 is a perspective view showing an induction heating type heater according to another embodiment of the present invention. The temperature sensor 6 arranged at a predetermined position on the annular heated body 21 is held by a holding device 44 attached to the upper portion 2 of the main body core. This holding device 44 is made of a non-magnetic material or an insulating material as in the previous embodiment to prevent unnecessary induction heating to this portion, and also an enlarged front view and a side view of a main part of FIG. As shown in FIGS. 6 and 7, the spring-shaped member is formed with a curved portion 45 in a part thereof so as to generate a pressing force, and is attached to a mounting portion 46 in which one end thereof is erected. An elongated slot 47 is provided, and the other end is brought into contact with the surface of the temperature sensor 6 with a spring force. As shown in FIG. 8 which is an enlarged front view of the main part of FIG. 5, one end of the holding device 44 is a mounting bolt 48 fixed to the upper portion 2 of the main body core.
Through the mounting oblong hole 47 of the mounting portion 46, and the mounting nut 4
It is attached using 9. On the other hand, the temperature sensor 6 is elastically moved by the free end of the holding device 44 after the detection end 11 is brought into contact with the inner ring of the annular heated body 21.
And holds the compensating lead wire 7 of the temperature sensor 6 as shown in FIG.
Is connected to the temperature sensor outlet 8 of the main body 1.

Also in this embodiment, the holding device 44 presses and holds the temperature sensor 6 at a predetermined position of the ring-shaped object to be heated 21, so that the ring-shaped object to be heated 21 is induced by electromagnetic induction during heating. Even if an attempt is made to make a slight movement on the holding table composed of the core guide cover 4 and the lower portion 10 of the main body core, the temperature sensor 6 is prevented from coming off from the predetermined position of the annular heated body 21 unlike the conventional case. ,
It is possible to accurately measure the temperature of the annular heated body 21 and prevent overheating.

FIG. 9 is a perspective view of an electromagnetic induction heater according to still another embodiment of the present invention. The temperature sensor 6 placed on the holding base constituted by the core guide cover 4 and the main body lower part 10 via the annular auxiliary base 23 is pressed and held by the holding device 54 provided separately from the main body. Has been done. The holding device 54 is made of a non-magnetic material or an insulating material as in the previous embodiment to prevent unnecessary induction heating to this portion, and the arm portion 53 is attached to the base 52. The arm portion 53 abutting on the rod-shaped core 24 is configured to have the same configuration as the holding devices 34 and 44 described in FIGS. 6 and 7 attached to the tip of the arm portion 53.
Ring-shaped object to be heated 2 due to vibration induced by electromagnetic induction during heating
Even if 1 moves slightly on the holding table, the temperature sensor 6 is not displaced from the predetermined position of the annular heated body 21 by the pressing force of the holding device 54 including the spring member.

Incidentally, the holding device 3 in the above-mentioned embodiment.
Although the springs 4, 44 and 54 are bent to generate a pressing force, they may have any shape as long as a pressing force can be obtained, and the attraction magnet provided in the temperature sensor 6 may be omitted.

[0017]

As described above, according to the present invention, since the temperature sensor is pressed and held by the holding device at the predetermined position of the ring-shaped object to be heated, the temperature sensor is moved by the slight movement generated when the ring-shaped object is heated. Therefore, it is possible to accurately measure the temperature of a predetermined position of the ring-shaped object to be heated by the temperature sensor, and it is possible to prevent overheating due to detachment of the temperature sensor as in the conventional case. .

[Brief description of drawings]

FIG. 1 is a perspective view of an electromagnetic induction heater according to an exemplary embodiment of the present invention.

FIG. 2 is an enlarged front view of a holding device in the electromagnetic induction heater shown in FIG.

FIG. 3 is an enlarged side view of a holding device in the electromagnetic induction heater shown in FIG.

FIG. 4 is an enlarged front view of a main part of the electromagnetic induction heater shown in FIG.

FIG. 5 is a perspective view of an electromagnetic induction heater according to another embodiment of the present invention.

6 is an enlarged front view of a holding device in the electromagnetic induction heater shown in FIG.

FIG. 7 is an enlarged side view of a holding device in the electromagnetic induction heater shown in FIG.

FIG. 8 is an enlarged front view of a main part of the electromagnetic induction heater shown in FIG.

FIG. 9 is a perspective view of an electromagnetic induction heater according to still another embodiment of the present invention.

FIG. 10 is a perspective view of a conventional electromagnetic induction heater.

FIG. 11 is an enlarged perspective view showing a temperature sensor.

FIG. 12 is a perspective view showing a different usage pattern of a conventional electromagnetic induction heater.

[Explanation of symbols]

 1 Main body 2 Main body core upper part 3 Rod-shaped core 4 Core guide cover 6 Temperature sensor 21 Bearing 23 Annular auxiliary stand 34,44,54 Holding device

Claims (1)

[Claims] 1. A magnetic circuit comprising an exciting coil wound around a removable rod-shaped core that penetrates an inner hole of an annular heated body, and a holder for holding the annular heated body. In the induction heating type heater, in which an alternating current is passed through the exciting coil, an alternating magnetic flux is generated in the annular heated body by an electromagnetic induction action to cause an eddy current, and the annular heated body is heated, the annular heated body A temperature sensor for detecting a temperature at a predetermined position of the excitation coil to control the energization of the exciting coil, and a holding device for holding the temperature sensor by pressing the temperature sensor against the annular heated body. Heating system heater.