JPH0495385A - Induction heating device - Google Patents

Abstract

PURPOSE:To eliminate a contacter for exclusive use of separating a capacitor, and reduce a dimension of a device by connecting each end of a heating coil and a capacitor, of which the other end is connected to each fixed contact point of a switch, to the other end of a power source respectively. CONSTITUTION:In a switch, a first fixed contact point 10 and a fixed contact point 11 are fitted to an insulating plate 12, and one end of a low temperature side coil 2A and the fixed contact point 10 are connected to each other, and the other end of the low temperature side coil 2A and the fixed contact point 11 are connected to each other. A second and a third fixed contact points 15, 16 and a fixed contact point 17 are fitted to an insulating plate 18, and one end of a low temperature side capacitor 4A and the fixed contact point 15 are connected to each other, and one end of a high frequency power source 1 and the fixed contact point 16 are connected to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an induction heating device used in the forging industry and the like, and particularly relates to a technique for switching connections between a plurality of heating coils, etc.

[Conventional technology]

FIG. 4 is a circuit diagram showing a schematic configuration of an induction heating device using a conventional heating coil connecting device disclosed in, for example, Japanese Utility Model Application Publication No. 57-11709.6.

In the figure, (1) is a high-frequency power supply that uses a transistor inverter, etc., and its output frequency is determined by the frequency because the current concentration due to the skin effect, which is determined by the frequency, affects the heating efficiency and the temperature distribution of the heated material. The frequency is set to a predetermined frequency that provides optimum characteristics. (2I is an arrow (3)
A heating coil that inductively heats a material to be heated that is transported in the direction of , and is composed of a low-temperature side coil (2A) and a high-temperature side coil (2B).

(2) is a capacitor connected in parallel with the heating coil (2). Similar to the heating coil [with], the low temperature side capacitor (4) is connected in parallel with the heating coil (2).
A) and a high temperature side capacitor (4B).

As shown in the figure, each capacitor is constructed by connecting a required number of unit capacitors in parallel. Then, the low temperature side coil (2A) and the low temperature side capacitor (4A)
) form a one-to-one pair, and the values of the former inductance and the latter capacitance are set so that they resonate at the output frequency of the high-frequency power source (1). The same applies to the pair of high temperature side coil (2B) and high temperature side capacitor (4B). (5) is a switch that connects and disconnects the low temperature side coil (2A) to the high frequency power source (1); (6)
is a contactor that connects and disconnects the low temperature side capacitor (4A) to and from the high frequency power source (1). The low-temperature side capacitor (4A), the high-temperature side capacitor (4B), and the contactor (6) are housed together in a capacitor board m.

Next, the operation will be explained. First, when the amount of heat treatment of the material to be heated (expressed, for example, by the number or weight of the material to be heated per unit time) is equal to or greater than a predetermined lower limit value, the switch (51) and the contactor ( 6) are closed, that is, all coils (2A) (2B) and all capacitors (4A) (4B) are connected to the high frequency power supply (1). 2
In the process of passing through the inside of the coil in the order of A)→high temperature side coil (2B), eddy current loss occurs due to electromagnetic induction, and the temperature is raised to about 1250° C., which is suitable for forging.

Then, the material to be heated is transferred to the heating coil (2) at a predetermined processing speed.
The length and power distribution of the heating coil (2) are set so that when the heating coil (2) travels inside, the temperature increases as the distance travels, and the temperature difference between the periphery and the center decreases.

By the way, in a forging forming machine, there are cases where, immediately after changing the forming die, several heated materials are forged as a test run, and the dimensions of the heated materials are inspected in the formed state. in this case,
As the processing speed of the heated material becomes slower, the relationship between the same position of the heating coil U and the temperature transition changes, and if the temperature is set at 1250°C on the outlet side, a high temperature part such as 1300°C will occur in the middle, causing problems such as welding of the heated material. occurs.

In order to solve this problem, the heating coil (2) is divided into two parts, and when the amount of heat processed becomes less than about 70% of the rated operation, the switch (5) is opened and only the high temperature side coil (2B) is opened. Heating is performed with In this case, if the connection of the capacitor (4) is left as is, the resonance frequency determined by the inductance of the heating coil will shift.
A) is separated from the circuit.

In addition, the low temperature side coil (2 people) and the low temperature side capacitor (4A
) is permanently connected, and if the circuit configuration is such that they both turn on and off the high frequency power supply (1) as one, the switch (51) and contactor (6
) can be shared, simplifying the circuit, but in this case, the low temperature side coil (2A) and the low temperature side capacitor (4A) are in a resonant relationship, so the electrical energy retained at the time of disconnection causes the circuit to become High voltage may be generated in the low temperature side coil (2A), which is unfavorable in terms of insulation design and work handling.

[Problem to be solved by the invention]

Since the conventional induction heating apparatus that switches the connection of the heating coil etc. according to the amount of heat treatment is configured as described above, it is necessary to disconnect the capacitor as well as the heating coil. For this reason, in addition to the switch (51), the contactor (6)
There was a problem in that the size of the capacitor panel opening increased accordingly.

This invention was made to solve the above-mentioned problems, and aims to reduce the size of the device by eliminating a contactor dedicated to disconnecting the capacitor.

[Means to solve the problem]

The induction heating device according to the present invention has a first fixed contact connected to one end of the heating coil, a second fixed contact connected to one end of the capacitor paired with the heating coil, and one end of the power source. The switch includes a third fixed contact, and a movable contact that can simultaneously connect and separate from the first to third fixed contacts.

[Effect]

The other ends of the heating coil and the capacitor connected to each fixed contact of the switch according to the present invention are respectively connected to the other end of the power source. When the switch is closed in this state, the heating coil and the capacitor are simultaneously connected to the power source in parallel.

Furthermore, when the switch is opened to separate the movable contacts from the fixed contacts, the heating coil and the capacitor are simultaneously disconnected from the power source and are also isolated from each other.

〔Example〕

FIG. 1 is a circuit diagram showing a schematic configuration of an induction heating device according to an embodiment of the present invention. In the figure, (11(2A)
(2B) (4A) (4B) is the same as the conventional one, but the device in this figure is usually called a two-line heating device.
Heating coil <2A) In addition to (2B), heating coil (9A
) (9B) is provided. The heating coils (2A) (2B) and (9A) (9B) of both series heat materials of different sizes, and a coil moving device (not shown) allows the heating coils to be moved in a short time. It is now possible to switch.

(8A) is the main part of this invention, and is a conventional switch (9A).
This switch has the functions of a contactor (6) and a contactor (6), the details of which will be described later based on FIGS. 2 and 3. (8B
) is a switch that connects and disconnects the high-temperature side coil (2B) to the high-frequency power source (1). For safety reasons during work, it is necessary to completely disconnect the unused heating coils from the high-frequency power source (1). It is intended to cut off the situation.

Next, details of the switch (8A) will be explained with reference to FIGS. 2 and 3. FIG. 2 is a configuration diagram showing the entire mechanism of the switch (8A), and FIG. 3 is a perspective view showing the fixed contact portion thereof.

In the figure, the first fixed contact is the fixed contact (11).
It is also attached to an insulating plate (12). (13)
and (14) are conductors that connect one end of the low temperature side coil (2A) and the fixed contact αO), and the other end of the low temperature side coil (2A) and the fixed contact (11), respectively. Note that the conductor is attached to the fixed contact by, for example, bolting using a tapped hole provided in the former. (
15] and (16) are the second and third fixed contacts,
It is attached to the insulating plate (18) together with the fixed contact (17).

(19) and (20) are conductors that connect one end of the low-temperature side capacitor (4A) and the fixed contact (+5), and one end of the high-frequency power supply (1) and the fixed contact (16), respectively;
(21) is the high frequency power supply (1) and the low temperature side capacitor (
4A) and the fixed contact (17). (22) and (23) are fixed contacts 0α(15) (16> and fixed contacts (l 1
) (+7) and its chevron-shaped part are movable contacts configured to be able to connect and separate at the same time. Although detailed illustrations are omitted, cooling water passages are formed by drilling holes in each of the fixed contacts 00), and cooling water is supplied through a hose (not shown) made of Tetron or the like. Further, a cooling vibrator is properly fixed to the conductor (13) etc. by brazing or the like, and cooling water is supplied into the cooling vibrator.

(24) is a hydraulic cylinder, which is connected to a movable contact (2) via a lever (26) rotatably supported by a support (25).
2) and (23) in their forward and backward directions. (2
7) is a disc spring for applying a predetermined adhesive pressure between the fixed and movable contacts.

Next, the operation will be explained. When the series of heating coils (2) is used and the amount of heat treatment is at a high level, the switch (8A) is closed together with the switch (8B). That is,
The switch (8A) is in the state shown in Figure 2. In this case, the fixed contact and the fixed contact (
15)<16), and the fixed contact (II) and the fixed contact (17) are in contact with each other via the movable contact (23). As a result, the low temperature side coil (2A) and low temperature side capacitor (4A) are connected in parallel to the high frequency power supply (
1). Here, a reliable contact state with sufficient precision can be obtained between the movable and fixed contacts mainly by controlling the parallelism and surface accuracy of the fixed contacts and the insulating plate.

Although the detailed structure of the switch (8B) is omitted, its structure is similar to that of the switch (8A), and its closing operation connects the high temperature side coil (2B) to the high frequency power source (1). That will happen.

Next, when the amount of heat treatment decreases and the switch (8A) is opened, operate the hydraulic cylinder (24) to open the lever (26).
) towards you. As a result, the movable contacts (22) and (23) both retreat and separate from the fixed contacts with which they were in contact. When the fixed contacts (15) and (16) separate from the movable contact (22), the connection between the phase tiles is also broken. Therefore, the low temperature side coil (2A)
and the low temperature side capacitor (4A) are both connected to the high frequency power supply (1A).
), and the parallel connection between them is also released.

In addition, in the above embodiment, by symmetrically arranging the parts where the current flows in opposite directions on the front and back sides of the insulating plate (12), etc., it is possible to suppress the increase in impedance and further suppress the local heat generation of the surrounding metal due to leakage magnetic flux. However, the present invention is not necessarily limited to the structure shown in FIG. 2 and the like.

For example, the movable contact may be of a semi-fixed configuration by tightening bolts, or may be a combination of a single-pole opening/closing type instead of the two-pole opening/closing type as described above.

Furthermore, although the above embodiment has been described with reference to two lines of heating coils, the present invention can be similarly applied to a heating coil with one line or three or more lines, and the same effect can be obtained.

Further, in the above embodiment, the heating coil is divided into two parts in the direction of progress of the process, but it may be divided into three or more parts.

〔Effect of the invention〕

Since this invention is configured as described above, a contactor dedicated to disconnecting the capacitor is not required, and the separation 1
The amount of space required within the system is reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of an induction heating device according to an embodiment of the present invention, FIGS. 2 and 3 are an overall configuration diagram and a partial perspective view showing details of a switch thereof, and FIG.
The figure is a circuit diagram showing a conventional induction heating device. In the figure, (1) is a high frequency power supply, (21 (2A) (2
B) is the heating coil, (41 (4A) (4B) is the capacitor, (8A) is the switch, 001, (+5) O and (1
6) C first, second and third fixed contacts, (
22) is a movable contact. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Figure 2 Figure 1 Figure 1, High School 1'' Separate power supply 2.2A, 2s: tJo-Y+Rule 4.4A, 4B: Container V each / Interval IvI Aoi 4th doctor

Claims (1)

[Scope of Claims] A plurality of sets each consisting of a power source, a heating coil for inductively heating a material to be heated, and a capacitor paired with the heating coil and having a capacitance that resonates with the inductance of the heating coil at the output frequency of the power source. a first fixed contact connected to one end of the heating coil; and a capacitor paired with the heating coil. A switch comprising a second fixed contact connected to one end, a third fixed contact connected to one end of the power source, and a movable contact that can simultaneously connect and disconnect from the first to third fixed contacts. An induction heating device characterized in that the number of sets is changed by operating the switch.