JP5103117B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating apparatus used for heat treatment such as quenching.

Parts made of carbon steel are quenched to increase the surface hardness. When quenching shafts, rails, etc., induction hardening is often performed by induction heating.
In the induction hardening, an induction heating coil is brought close to a work and an induction current is generated in the work to raise the temperature.
As a quenching apparatus that performs quenching using induction heating, the one disclosed in Patent Document 1 is known.

JP 2003-317913 A

In the induction hardening, an induction heating coil is energized with a high frequency current to generate a magnetic field and an induction current is generated in the work. Therefore, the induction heating coil and the work must always be in a non-contact state.
That is, when the induction heating coil and the workpiece come into contact with each other, large electricity flows directly from the induction heating coil to the workpiece, and the contact portion melts. For this reason, when the induction heating coil and the workpiece come into contact with each other, it is necessary to immediately issue a warning for notifying the worker of this or stop the apparatus.

As a circuit for knowing that the induction heating coil and the workpiece are in contact with each other, for example, a circuit as shown in FIG.
The detection circuit shown in FIG. 7 includes a low voltage supply circuit 100 and applies a low voltage between the induction heating coil 10 and the ground via the transformer 101 from the low voltage supply circuit 100. In the conventional detection circuit, a relay 103 is inserted in the low voltage supply circuit 100 (primary side of the transformer 101). When a certain current or more is supplied to the coil, the relay 103 is turned on or off by operating a contact (not shown).

In the detection circuit shown in FIG. 7, when the induction heating coil 10 and the work contact, the secondary side of the transformer 101 is short-circuited via the induction heating coil 10 and the work. As a result, the impedance on the primary side of the transformer 101 decreases and a large current flows on the primary side of the transformer. As a result, the relay 103 is driven, the contact is turned on or off, and a predetermined measure such as an alarm is displayed.

However, according to the detection circuit shown in FIG. 7, when the induction heating coil 10 and the work come into contact with each other, a high-frequency current flowing through the induction heating coil 10 flows through the transformer 101 of the low voltage supply circuit 100. Therefore, the transformer 101 may generate heat, and in a severe case, the transformer 101 may be burned out.

  Then, this invention proposes the new policy which detects the contact of an induction heating coil and a workpiece | work, and makes it a subject to provide the induction heating apparatus with few failures.

The invention according to claim 1, which is provided to solve the above-described problem, is an induction heating apparatus including an induction heating coil for induction heating of an object to be processed, wherein the induction heating coil is an object to be processed during heat treatment. a heating unit that is disposed at a position facing the object, definitive in the circuits supplying power to the induction heating coil or induction heating coils, on both sides of the heating unit, provided each current sensing means, said The induction heating apparatus is characterized in that the current detected by each of the current detection means is constantly monitored, and a predetermined treatment is performed when an abnormality of a certain level or more occurs in both.

According to a second aspect of the present invention, in the induction heating apparatus provided with an induction heating coil for induction heating the object to be processed, the induction heating coil is arranged at a position facing the object to be processed during the heat treatment. a heating unit, definitive in the circuits supplying power to the induction heating coil or induction heating coils, on both sides of the heating unit, provided each current detector, current sensed by said each current sensing means constantly monitors the an inductive heating device, characterized in that the predetermined treatment is performed when more than a predetermined difference occurs in both.

The induction heating apparatus of the present invention, the induction heating coil, a heating unit that is disposed at a position facing the processing object at the time of heat treatment, definitive in the circuits supplying power to the induction heating coil or induction heating coils, Current detection means are provided on both sides of the heat treatment unit, and the current detected by each current detection means is constantly monitored. Here, since two or more current detection means are provided on both sides of the heat treatment unit in the induction heating coil or the circuit for supplying power to the induction heating coil , the same current value should be detected. . That is, the two ammeters shown in FIG. 6 show the same value. Since high frequency current is supplied to the induction heating coil, basically the same current flows. For example, if the work and the induction heating coil are not in contact with each other, the same current Ic flows through the current detection means CT1 and CT2.
However, when the workpiece and the induction heating coil come into contact with each other, the current Ic flows through one part (the part of the current detecting means CT1), but the other part (the part of the current detecting means CT2) sandwiching the contact point is grounded. Since the current IL also flows, the current detected by the current detection means CT2 becomes (Ic−IL), and there is a difference that is an abnormal value between the two.
In the present invention, if the abnormal value or the difference is equal to or greater than a certain value, a predetermined treatment is performed.

  The invention according to claim 3 is the induction heating apparatus according to claim 1 or 2, wherein the predetermined treatment is an indication of abnormality.

  According to a fourth aspect of the present invention, the induction heating coil has a heat treatment part disposed at a position facing the object to be treated during the heat treatment, and a conduction part electrically connected to the heat treatment part. , Two conductive parts electrically connected to the heat treatment part across the heat treatment part, each of the two conductive parts is provided with a current detection means, the current detection means is a core made of a magnetic material The induction heating device according to claim 1, wherein the portion is attached via an insulator, and a current detection coil is provided in the core portion.

In the induction heating coil employed in the present invention, a core portion made of a magnetic material is disposed at a position adjacent to the conduction portion, and a current detection coil is attached thereto. Therefore, when the induction heating coil of the present invention is energized to perform the quenching process, an induction current flows through the current detection coil wound around the core portion.
That is, since a high-frequency current is passed through the induction heating coil, a varying magnetic field is generated around the conducting portion, and the core is exposed to the varying magnetic field. As a result, the core is penetrated by the changing magnetic flux, and an induced current is generated in the current detection coil wound around the core portion.
Therefore, the induction heating coil of the present invention can detect the energization state to the induction heating coil by detecting the induction current flowing through the current detection coil.
In the induction heating coil of the present invention, it is assumed that an induction current having a magnitude reflecting the magnitude of the current flowing through the heat treatment portion flows through the current detection coil. Therefore, when performing induction heating and quenching using the induction heating coil of the present invention, it is possible to monitor the transition of the current value flowing through the heat treatment unit by monitoring the induction current value.
Furthermore, since the present invention detects the current by picking up the magnetic flux leaking from the induction heating coil, the inductance of the induction heating coil itself does not change. Therefore, there is no loss in the current flowing through the induction heating coil.
Further, in the present invention, the core portion because that is attached to the induction heating coil via the insulator, the core portion is insulated from the induction heating coil. Therefore, even if there is an insulation failure in the current detection coil, an excessive current does not flow to the measuring instrument side.

  According to the induction heating device of the present invention, it is possible to reliably detect contact between the induction heating coil and the workpiece.

Next, the induction heating device 1 and the induction heating coil 10 according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit configuration diagram of an induction heating apparatus according to an embodiment of the present invention. FIG. 2 is a conceptual diagram of the induction heating coil according to the embodiment of the present invention. 3 is a perspective view and an exploded perspective view of a core portion of the induction heating coil of FIG. FIG. 4 is a perspective view of the core portion of the induction heating coil in another embodiment.
As shown in FIG. 1, the induction heating device 1 (hereinafter also referred to as a quenching device 1) includes a high-frequency power source 2, a heating unit 3, and a control device 5.

  The high-frequency power source 2 can receive high-frequency power on the secondary side by receiving power from an AC power source AC (not shown) electrically connected to the primary side. A heating unit 3 is connected to the secondary side of the high frequency power source 2 so that the high frequency power generated by the high frequency power source 2 can be supplied to the heating unit 3. The heating unit 3 includes an induction heating coil 10 and a current transformer 11.

  A secondary side of the current transformer 11 constitutes a heating circuit unit 30. The heating circuit unit 30 is a portion connected to the secondary side of the current transformer 11 described above, and is configured around the induction heating coil 10. The heating circuit unit 30 is provided with a voltmeter 34 for detecting the voltage applied to the induction heating coil 10.

The induction heating coil 10 is a coil provided for induction heating of a processing object to be quenched. The induction heating coil 10 is a circular coil as shown in FIG.
The induction heating coil 10 includes a heat treatment unit 31 disposed on the outer peripheral side of the object to be treated during the quenching process, and an energization unit 32 connected to the secondary side of the current transformer 11.
The two energization parts 32 are in a position sandwiching the heat treatment part 31.

As shown in FIG. 2 and FIG. 3, current detection means 50 and 51 are provided in the two energization portions 32 of the induction heating coil 10, respectively.
Since the two current detection means 50 and 51 have the same structure, the structure will be described by taking one current detection means 50 as an example. In the present embodiment, the current detection means 50 includes a core member 35 (core portion), an insulator 39, and a current detection coil 38.
A core member 35 (core part) constituting the current detection means 50 is attached to the energization part 32 via an insulator 39. The insulator 39 is a thin plate made of resin, mica, or the like.
The core member 35 is made of a magnetic material and has a substantially “B” -shaped appearance. That is, the core member 35 is a frame that forms a rectangular closed loop, and the core member 35 is attached to the energizing portion 32 in a cantilever manner as shown in FIG.

More specifically, the core member 35 includes a fixing portion 37 that is fixed to the energization portion 32 of the induction heating coil 10 and a core portion 36 that is in a positional relationship substantially parallel thereto. There is a space 41 between the fixed portion 37 and the core portion 36.
The aforementioned insulator 39 is interposed between the fixed portion 37 and the energizing portion 32, and the fixed portion 37 and the energizing portion 32 are electrically insulated. In the present embodiment, the mounting posture of the core member 35 is a posture in which the fixed portion 37 and the core portion 36 are parallel to the current flow direction of the energizing portion 32 as shown in FIGS. As shown, the fixed portion 37 and the core portion 36 may be attached in a posture orthogonal to the current flow direction.

  A current detection coil 38 is wound around the core portion 36. The current detection coil 38 is constituted by a conductive linear conductor or a covered electric wire, and is not in direct contact with the secondary side electric system 33 or the induction heating coil 10. That is, the current detection coil 38 is present at a position adjacent to the energization portion 32 of the induction heating coil 10.

An ammeter 40 (current detection means) is connected to the current detection coil 38. Therefore, when electric power is supplied to the secondary side of the current transformer 11, the current Ic flows through the induction heating coil 10, and the current value that flows through the induction heating coil 10 through the current detection coil 38 wound around the core portion 36. An induced current Iy having a corresponding magnitude flows, and this is detected by the ammeter 40.
The signals of the current detection coils 38 of the two current detection means 50 and 51 are input to the control device 5 and monitored.

  The control device 5 monitors the magnitude of the electric power supplied to the induction heating coil 10 based on the voltage value detected by the voltmeter 34 provided in the heating unit 3 and the current value detected by the ammeter 40. ing. Further, the control device 5 determines the degree of quenching of the object to be processed in which the application state of the electric power to the induction heating coil 10 is subjected to the quenching process based on the voltage value or the current value detected by the voltmeter 34 or the ammeter 40. Adjustment is made so as to obtain an optimum state for the predetermined state. That is, the control device 5 adjusts the power applied to the induction heating coil 10 based on the voltage value, current value, and the like detected by the voltmeter 34 and the ammeter 40.

In the quenching apparatus 1 of the present embodiment, the core member 35 is attached in the middle of the conduction portion 32 that constitutes the induction heating coil 10, and the core portion 36 of the core member 35 is energized as the induction heating coil 10 is energized. An induced current Iy corresponding to the amount of current supplied to the induction heating coil 10 flows through the attached current detection coil 38. The induced current Iy can be detected by the ammeter 40. Therefore, if the quenching process is performed by the quenching apparatus 1, the current value of the induction current Iy detected by the ammeter 40 provided in the heating circuit unit 30 is monitored to thereby determine the magnitude of the current flowing through the induction heating coil 10. It can be accurately grasped.

  In the quenching apparatus 1 of the present embodiment, the magnitude of the current value flowing by energization for each induction heating coil 10 can be grasped, and the voltage value acting on the induction heating coil 10 can be grasped by the voltmeter 34. Therefore, the quenching apparatus 1 can monitor the magnitude of the power applied to the induction heating coil 10 and make the power supply state suitable for the quenching process.

Furthermore, in the hardening apparatus 1 of this embodiment, the signals of the current detection coils 38 of the two current detection means 50 and 51 are input to the control device 5 and are constantly monitored and compared. When the difference between the two exceeds a certain value, an alarm signal is issued from the control device 5.
That is, since the current detection means 50 and 51 are connected in series, both currents should be the same.
However, if the induction heating coil 10 and the workpiece come into contact with each other, a current flows from the induction heating coil 10 to the workpiece, the equilibrium relationship is lost, and the current values detected by the current detection means 50 and 51 differ. Therefore, the present invention constantly monitors and compares the signals of the current detection coils 38 of the two current detection means 50 and 51, and if the difference between the two exceeds a certain value, the induction heating coil 10 and the workpiece are in contact with each other. Judgment and issue an alarm.

The induction heating coil 10 employed in the quenching apparatus 1 is provided with a core member 35 at a position away from the heat treatment unit 31 that becomes extremely high when energized, specifically, the energization unit 12. That is, the core member 35 is provided to avoid a portion that becomes excessively hot when energized. Therefore, according to the above-described configuration, adverse effects due to the high temperature of the core member 35, such as the current detection coil 38 being melted, are unlikely to occur.

The induction heating coil 10 is provided with a core member 35 at a position away from the heat treatment unit 31 , and a current detection coil 38 is present at a position away from the position where the object to be treated is disposed during the quenching process. Yes. Therefore, when performing the quenching process using the induction heating coil 10, the core member 35 and the induction heating coil 10 do not interfere with the quenching process. Moreover, since the core apparatus 35 and the induction heating coil 10 are provided in the position where the hardening member 1 does not interfere with the quenching process, the induction heating coil 10 can be arranged at a high density according to the object to be processed. it can.

In the embodiment described above, a circular shape is exemplified as the coil shape, but the present invention can also be applied to coils having other shapes.
FIG. 5 is a conceptual diagram of an induction heating coil according to another embodiment of the present invention.
An induction heating coil 53 shown in FIG. 5 is a so-called open-type saddle coil formed by, for example, bending a pipe having a square cross section in a complicated manner. If it demonstrates in detail, the induction heating coil 53 is made into a series from the one end side (end part 10a) to the other end side (end part 10b). In addition, the induction heating coil 53 communicates over the entire section from the end 10a to the end 10b with respect to the liquid passage 45 formed therein.

  The induction heating coil 53 includes a heat treatment unit 31 located on the lower side and a conduction unit 32 located on the upper side in the state shown in FIG.

In the state shown in FIG. 5, the conduction part 32 is located above the heat treatment part 31, and has a first conduction part 32a, a second conduction part 32b, and an intermediate conduction part 32c. The 1st conduction | electrical_connection part 32a is a part from the edge part 10b side to the heat processing part 31, and is connected with the horizontal part 82 located in the upper side in the 1st heat processing part 31a . Moreover, the 2nd conduction | electrical_connection part 32b is a part from the edge part 10a side to the heat processing part 31, and is connected with the horizontal part 88 located in the downward side in the 2nd heat processing part 31b . A slight gap is provided between the first and second conducting portions 32a and 32b, and the two are insulated.

  As shown in FIG. 5, the core member 35 is attached to the first conduction portion 32a in a cantilever manner by welding or the like. An insulator (not shown) is interposed between the core member 35 and the first conduction portion 32a, and the core member 35 and the first conduction portion 32a are electrically insulated. Further, a current detection coil 38 is attached to the core portion 36 of the core member 35.

  Similarly, the core member 35 is attached to the first conduction portion 32b in a cantilever manner by welding or the like. An insulator (not shown) is interposed between the core member 35 and the first conduction portion 32a, and the core member 35 and the first conduction portion 32a are electrically insulated. A current detection coil 38 is attached to the core portion 36 of the core member 35.

  Therefore, as in the previous embodiment, the current Ic flows through the induction heating coil 53, and the induction current Iy having a magnitude corresponding to the current value flowing through the induction heating coil 10 flows through the current detection coil 38 wound around the core portion 36. This is detected by the ammeter 40.

The control device 5 monitors the induction current Iy flowing in the current detection coil 38 attached to the core member 35 of each induction heating coil 10 by the ammeter 40 provided for each coil unit 60. Based on the voltage value detected by the voltmeter 34 and the current value detected by the ammeter 40, the control device 5 confirms whether or not a conduction failure has occurred in each induction heating coil 10, and each induction heating coil. The power supply amount to 10 is appropriately adjusted.

  Further, the control device 5 compares the signals of the current detection coils 38 of the two current detection means 50 and 51, and if the difference between the two exceeds a certain value, it is considered that the induction heating coil 10 is in contact with the workpiece and an alarm signal is received. To emit.

It is a circuit block diagram of the induction heating apparatus concerning one Embodiment of this invention. It is a conceptual diagram of the induction heating coil of embodiment of this invention. It is the perspective view (a) and exploded perspective view (b) of the core part of the induction heating coil of FIG. It is a perspective view of the core part of the induction heating coil in other embodiment. It is a conceptual diagram of the induction heating coil of other embodiment of this invention. It is a conceptual diagram which shows the principle of the induction heating apparatus of this invention. It is a conceptual diagram which shows the principle of the hardening apparatus provided with the other contact detection circuit.

1 Induction heating device (quenching device)
2 High-frequency power supply 3 Heating unit 10 Induction heating coil 11 Current transformer 31 Heat treatment part 32 Conducting part 35 Core member (core part)
39 Insulator 38 Current detection coil 40 Ammeter (current detection means)
50, 51 Current detection means

Claims (4)

In the induction heating apparatus provided with the induction heating coil for induction heating the object to be treated, the induction heating coil has a heat treatment part arranged at a position facing the object to be treated at the time of the heat treatment, and the induction heating coil or induction definitive circuit supplying the heating coil power, the heat treatment unit opposite sides of the provided each current sensing means, said constantly monitors the current sensed by the current sensing means, both above a certain An induction heating apparatus, wherein a predetermined treatment is performed when an abnormality occurs. In the induction heating apparatus provided with the induction heating coil for induction heating the object to be treated, the induction heating coil has a heat treatment part arranged at a position facing the object to be treated at the time of the heat treatment, and the induction heating coil or induction definitive circuit supplying the heating coil power, the heat treatment unit opposite sides of the provided each current sensing means, said constantly monitors the current sensed by the current sensing means, both above a certain An induction heating apparatus, wherein a predetermined treatment is performed when a difference occurs.   The induction heating apparatus according to claim 1 or 2, wherein the predetermined treatment is a display of an abnormality.   The induction heating coil has a heat treatment unit disposed at a position facing the object to be treated at the time of the heat treatment, and a conduction unit electrically connected to the heat treatment unit, and the heat treatment is performed with the heat treatment unit interposed therebetween. Each of the two conducting portions is provided with a current detecting means, and the current detecting means has a core portion made of a magnetic material attached via an insulator. The induction heating apparatus according to claim 1, wherein a current detection coil is provided in the core portion.

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