JP2745101B2 - High frequency heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high frequency current oscillated by a single high frequency oscillation circuit having a frequency of 20 kHz or more, which is supplied through an air-core transformer (transformer having no core such as a silicon steel plate). Multiple (three or more)
When a plurality of (three or more) same workpieces are simultaneously heated by a high-frequency heating coil (hereinafter, the high-frequency heating coil is also simply referred to as a heating coil), an abnormality caused by a change in the impedance of any one of the heating coils may occur. High easily detectable
It relates to a frequency heating device .

[0002]

2. Description of the Related Art Conventionally, a high-frequency current of a relatively high frequency (usually 20 kHz or more) oscillated by a high-frequency oscillation circuit using a vacuum tube or the like is supplied to a plurality of heating coils via an air-core transformer, and the plurality of heating coils are supplied. In a high-frequency heating apparatus in which a heating coil simultaneously quenches and heats a plurality of works, for example, as a test, a plurality of works are simultaneously quenched by the plurality of heating coils, and then each work is subjected to destructive inspection. After measuring the specifications such as depth and hardness of the formed hardened layer, and confirming that the quenching heating and cooling of the work have been properly performed, mass production quenching is performed.

[0003]

However, since it is not possible to confirm whether or not the quenching of mass-produced quenched workpieces has been properly performed, the quenching quality of each of the quenched workpieces can be reduced. The above concerns remain. This is because, in a high-frequency heating apparatus that includes a plurality of heating coils and simultaneously heats a plurality of workpieces, for example, by quenching, often (1) short-circuit or ground fault occurs in one of the heating coils. (2) An abnormality may occur such that one of the heating coils is not accurately moved to the heating position, that is, the position of any one of the heating coils relative to the work is slightly different. Since the probability that an abnormality occurs simultaneously in two or more heating coils is extremely low, it is assumed that an abnormality occurs in only one heating coil.

[0004] If the work is heated in a state where such an abnormality has occurred in the heating coil, the work cannot be heated to a predetermined temperature, depth, and range. Means that a predetermined hardened layer is not formed after cooling the work. However, short-circuiting of any one of a plurality of heating coils for simultaneously heating a plurality of works by receiving a high-frequency current from the high-frequency power supply through an air-core transformer, occurrence of a ground fault, and slight displacement of the position with respect to the work are described. It was difficult to detect such a disorder.

[0005] The reason is that the power factor of the heating coil is generally about 0.2, for example, and the power factor when the air core transformer having the heating coil connected to the secondary side is viewed from the primary side is even lower, for example.
Since it is about 0.03 to 0.04, the heating coil connected to the secondary side of the air-core transformer has the short-circuit and ground fault as described above, and furthermore, the position of the heating coil on the secondary side of the air-core transformer due to misalignment with respect to the work. Even if there is a change in impedance, this change is very rarely transmitted to the primary side of the air-core transformer, so that no change is observed in the anode current, grid current, or anode voltage of the high-frequency oscillation circuit, for example, a vacuum tube. Therefore, it has been difficult to detect the above-described abnormality of a plurality of heating coils connected to an air-core transformer and heating a plurality of workpieces at the same time only by a meter provided in a conventional high-frequency oscillation circuit.

The present invention has been made in view of such circumstances, and has a relatively high frequency (usually 20 kHz) at which one high-frequency oscillation circuit having a primary coil of an air-core transformer as an oscillation circuit element oscillates. Above)
Provided is a high-frequency heating device capable of easily detecting an abnormality accompanying a change in impedance of a heating coil when an air-core transformer is supplied to a plurality of heating coils and the plurality of heating coils simultaneously heat a workpiece. The purpose is.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problem, a high-frequency heating apparatus according to the first aspect of the present invention comprises:
The air core transformer and the primary coil of the air core transformer are oscillated.
One vacuum tube type high frequency oscillation circuit
When connected in series between the secondary coils of the air core transformer,
The high-frequency oscillator oscillated by the high-frequency oscillation circuit
High frequency current is supplied through the primary and secondary coils.
And three or more high-frequency heating coils,
With the high frequency heating coil above, three or more similar workpieces
In a high-frequency heating device that simultaneously heats each,
Between each coil end of three or more high-frequency heating coils
3 connected to detect the AC voltage between both ends of each coil
Equipped with the above AC voltmeter, the three or more AC voltmeter
Compare the magnitudes of the detected AC voltages
As a result, it is detected that the magnitude of the AC voltage between both ends of any one of the high-frequency heating coils in which an abnormality accompanied by an impedance change is different from that of the other high-frequency heating coils. And one of the high
Is configured to detect the occurrence of abnormalities in the frequency heating coil.
It is characterized by having .

[0008] In order to solve the above problem, the high frequency heating apparatus according to the second aspect of the present invention comprises three or more air core transformers.
And three or more air-core transformers connected in series or in parallel
Equipped with three or more primary coils as oscillation circuits
Two vacuum-tube high-frequency oscillation circuits and three or more air cores
Connected to the secondary coil of the transformer
The high frequency of the high frequency oscillated by the high frequency oscillation circuit
Current flows through the primary and secondary coils of each of the air core transformers.
And three or more high-frequency heating coils supplied as
And three or more high-frequency heating coils,
A high-frequency heating device that simultaneously heats the same type of work
In addition, each coil of the three or more high-frequency heating coils
The AC voltage between both ends of each coil
Equipped with 31 or more AC voltmeters to detect, and 3 or more
Of the AC voltage detected by each AC voltmeter
By comparing the magnitudes, the magnitude of the AC voltage between both ends of any one of the high-frequency heating coils in which an abnormality involving impedance change has occurred is different from the magnitude of the AC voltage between both ends of the other high-frequency heating coil. Detect that
Detects the occurrence of an error in one of the high-frequency heating coils
It is characterized by having such a configuration .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view of an embodiment of the invention described in claim 1, and FIGS. 2 and 3 are explanatory views of first and second embodiments of the invention described in claim 2, respectively.

First, an embodiment of the present invention will be described. As shown in FIG. 1, three heating coils 11 to
A high-frequency current transmitted using a vacuum tube (which can be a semiconductor element) VT is a single air-core transformer T.
0 to simultaneously heat three identical workpieces (not shown).

More specifically, a high-frequency oscillation circuit HF
The GA includes a DC power supply DCS, a switch SW for turning on and off the DC power supply DCS, a three-pole vacuum tube VT supplied with a DC voltage from the DC power supply DCS, and a block for preventing a high-frequency current from flowing into the DC power supply DCS. High-frequency choke coil RFC and capacitor C1 that bypasses high-frequency current to DC power supply DCS
A coil Lg for detecting a resonance voltage, one end of which is connected to the lattice of the vacuum tube VT, a coil Lp for applying a voltage to the coil Lg, and a primary coil 11 of a transformer 10 connected in series to the coil Lp. A blocking capacitor C2 for blocking the direct current from the DC power supply DCS from flowing through the coil Lp and the primary coil 11 of the transformer 10, and a resonance capacitor C3 connected in parallel with the coil Lp and the primary coil 11 of the transformer 10. And the lattice bypass capacitor C of the vacuum tube VT
4, a grid resistor R2 connected to the other end of the coil Lg,
It includes a DC anode voltmeter Ep, an instrument resistor R1, a DC anode ammeter Ip, and a DC grid ammeter Ig.

Three heating coils 11 for heating three same works are provided between both ends of the secondary coil T02 of the air-core transformer T0.
To 13 are connected in series. The details of each heating coil will be described taking the heating coil 11 as an example.
A pair of lead conductors 11b, 11c and these lead conductors 11b
, 11c connected between the ends of the heating conductor 11a for heating the work. Then, the lead conductors 11b and 11c
A pair of connecting members K for connecting the heating coil 11 to the secondary coil T02 so as to be able to contact and separate from the base end thereof, and a lead conductor 11b.
, 11c are provided with an AC voltmeter V connected between them. The other heating coils 12 and 13 are provided with the same lead conductor, heating conductor, connecting member K, and AC voltmeter V as the heating coil 11.

Next, a case where a plurality of works are simultaneously quenched and heated by the heating coils 11 to 13 will be described. When the switch SW of the high-frequency oscillation circuit HFGA is turned on, high-frequency oscillation (oscillation voltage is 3 kV or more) is started by the vacuum tube VT, and the oscillated high-frequency current (frequency is usually 20 kHz or more) is applied to the primary coil T01 of the air-core transformer T0. Flows. Accordingly, a high-frequency current is induced in the secondary coil T02 of the air-core transformer T0,
This high-frequency current flows through the heating coils 11 to 13 and simultaneously heats the three works. After the switch SW is turned off, the heating coils 11 to 13 are separated from the three works, and then the three works are separated. Upon cooling, a hardened layer is formed on these works.

If there is no abnormality in any of the heating coils during energization of the heating coils 11 to 13, the indicated values of the AC voltmeter V of the heating coils 11 to 13 are equal. However, if the heating coils 11 to 13 are energized while the position of the heating coil 11 with respect to the workpiece is slightly different, or
If, for example, a short circuit or ground fault occurs in the heating coil 11 during energization of the heating coil 11, the impedance of the heating coil 11 changes, so that the magnitude of the current flowing through the heating coils 11 to 13 changes. As a result, the indicated value of the AC voltmeter V between both ends of the heating coil 11 differs from the indicated value of the AC voltmeter V of the heating coils 12 and 13 where no abnormality has occurred. Therefore, by monitoring the three AC voltmeters V, it is easily understood that an abnormality has occurred in the heating coil 11.

Next, a first embodiment of the present invention will be described. In this embodiment, an air core transformer is provided for each heating coil. As shown in FIG. 2, the high-frequency oscillation circuit HFGB is almost the same as the high-frequency oscillation circuit HFGA described in the above embodiment, except that the coil Lp, the air-core transformer T1
Primary coil T11, primary coil T2 of air-core transformer T2
1 in that the primary coil T31 of the air-core transformer T3 is connected in series. Then, secondary coils T12, T3 of three air-core transformers T1, T2, and T3
Heating coils 21 to 23 are connected to both ends of the heating coils 22 and T32 via a pair of connecting members K, respectively. An AC voltmeter V is connected between both ends of the heating coils 21 to 23. It is connected.

When the three coils are simultaneously heated by the heating coils 21 to 23 and an abnormality accompanied by the impedance change occurs in any one of the heating coils, the AC voltage of the heating coil is changed in the same manner as in the first embodiment. The indicated value of the meter V differs from the indicated value of the AC voltmeter V of the other heating coils. Therefore, when monitoring three AC voltmeters V,
The occurrence of an abnormality in the heating coil can be easily recognized.

A second embodiment of the present invention will be described. Also in this embodiment, an air core transformer is provided for each heating coil. As shown in FIG.
The difference is that the primary coils T11, T21, and T31 of the air-core transformers T1, T2, and T3 are connected in parallel to the coil Lp, respectively, as compared with the high-frequency oscillation circuit HFGB. . Air core transformer T1, T2, T
The heating coils 31 to 33 and the AC voltmeter V are connected to the secondary coils T12, T22, and T32 through a pair of connecting members K, respectively, as in the first embodiment described with reference to FIG. It is connected. Also in the present embodiment, when an abnormality occurs in any one of the heating coils 31 to 33, the indication value of the AC voltmeter V of the heating coil is changed to the other heating coil as in the previous embodiment. It differs from the indicated value of the AC voltmeter V. Therefore, when monitoring three AC voltmeters V,
The occurrence of an abnormality in the heating coil can be easily recognized.

In the above-mentioned three embodiments, the case where the number of the heating coils is three has been described. However, the number of the heating coils is not limited to three and may be an arbitrary number of three or more.

[0019]

As described above, the high-frequency heating device according to the first aspect of the present invention provides a single vacuum-tube high-frequency oscillation circuit.
Using one air-core transformer driven by
When simultaneously heating the same kind of work with high frequency, one piece
Is connected in series between both ends of the secondary coil of the air core transformer
The AC voltage across each of the three or more high-frequency heating coils
Detect and compare the magnitude of the detected AC voltage
More, the magnitude of the AC voltage across any one of the high-frequency heating coil abnormality with the impedance change has occurred, and detects that is different from the magnitude of the AC voltage across the other high frequency heating coil So the air core transformer
Any one without being affected by changes in force over time
The occurrence of abnormalities in the high-frequency heating coil
Wear.

The high-frequency heating device according to the second aspect of the present invention.
Is driven by one vacuum tube type high frequency oscillation circuit.
Using three or more air core transformers, three or more
3 or more air cores
Three or more lances connected between both ends of each secondary coil
Detects and detects the AC voltage across each end of the high-frequency heating coil
By comparing the magnitudes of the applied AC voltages, the magnitude of the AC voltage between both ends of any one of the high-frequency heating coils in which an abnormality involving impedance change has occurred is determined by comparing the magnitude of the AC voltage between both ends of the other high-frequency heating coil. and detects that it is different from the magnitude of the voltage, a time of output of the air-core transformer
High frequency heating of any one without being affected by change
The occurrence of a coil abnormality can be accurately known.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the invention described in claim 1;

FIG. 2 is an explanatory diagram of a first embodiment of the invention described in claim 2;

FIG. 3 is an explanatory view of a second embodiment of the invention described in claim 2;

[Explanation of symbols]

 11-13, 21-23, 31-33 Heating coil HFGA, HFGB, HFGC High frequency oscillation circuit T0, T1, T2, T3 Air core transformer T01, T11, T21, T31 Primary coil T02, T12, T22, T32 Secondary Coil V AC voltmeter

Claims (2)

(57) [Claims] 1. An air-core transformer and said air-core transformer
One vacuum tube type equipped with a primary coil as an oscillation circuit
Between the high frequency oscillation circuit and the secondary coil of the air core transformer
Connected in series and by the high frequency oscillation circuit
The oscillated high frequency high-frequency current is the primary and secondary
Three or more high-frequency heating coils supplied via coils
And the three or more high-frequency heating coils
High-frequency heating for heating at least
In the heating device, the heat is applied between both ends of the three or more high-frequency heating coils.
Connected to detect AC voltage across each coil
It has three or more AC voltmeters, and the three or more AC voltmeters
The magnitude of the AC voltage detected by the
By doing so, the magnitude of the AC voltage between both ends of one of the high-frequency heating coils in which an abnormality involving impedance change has occurred is different from the magnitude of the AC voltage between both ends of the other high-frequency heating coil. Detect and one of them
Configured to detect the occurrence of abnormalities in the high-frequency heating coil
High frequency heating apparatus characterized by being. 2. An air-core transformer having three or more cores and three or more air-core transformers
Three or more air core transformers connected in series or in parallel
One vacuum tube type equipped with a primary coil as an oscillation circuit
High frequency oscillation circuit and secondary of three or more air core transformers
Connected to the coil and the high-frequency oscillation circuit.
The high-frequency high-frequency current oscillated by the
Supplied via primary and secondary coils of core transformer
And three or more high-frequency heating coils.
High frequency heating coil removes three or more similar workpieces
In a high-frequency heating device that heats each of the three or more high-frequency heating coils at the same time,
Connected to detect AC voltage across each coil
It has three or more AC voltmeters, and the three or more AC voltmeters
The magnitude of the AC voltage detected by the
As a result, the magnitude of the AC voltage between both ends of any one of the high-frequency heating coils in which an abnormality involving impedance change has occurred is different from the magnitude of the AC voltage between the re-ends of the other high-frequency heating coils And one of them
Configured to detect the occurrence of abnormalities in the high-frequency heating coil
High frequency heating apparatus characterized by being.