JP5942293B2 - Induction heating system and method - Google Patents

Description

  The present invention relates to an induction heating system and method for supplying power of different frequencies to each of a plurality of induction heaters.

  Multiple induction heaters of different types are arranged to inductively heat the workpiece according to the shape of the workpiece and the part to be heat-treated, or according to the arrangement of the heating coil with respect to the workpiece and the support mode of the workpiece. Is done. For example, when induction heating is performed, since the penetration depth of the magnetic flux generated from the heating coil from the surface to be processed into the inside varies depending on the frequency, the frequency is selected according to the thickness of the heat treatment layer. A low frequency is used to make the heat treatment layer thick, and a high frequency is used to make the heat treatment layer shallow. Therefore, there is a system configuration in which power supplies having different output frequencies are arranged so that the workpiece is induction-heated at different frequencies, and each induction heating apparatus is connected to each power supply via a switch (for example, a patent) Reference 1).

  Furthermore, in recent years, induction heating is performed using a plurality of frequencies without performing induction heating at one frequency. For example, heat treatment is performed by simultaneously superimposing a low frequency and a high frequency.

JP-A-60-249288

  However, if a power feeding system that outputs electric power of a plurality of frequencies is arranged for one induction heater, the equipment becomes large and the induction heating system itself becomes expensive. Further, in the system disclosed in Patent Document 1, heating coils having different shapes and sizes are attached between induction heaters, and a time chart for power supply to each heating coil cannot be freely set. Moreover, assuming that the thickness of the heat treatment layer varies from work to work, or various heat treatments such as quenching and tempering are performed for each induction heater, the load impedance including the work is different for the power feeding system. It is necessary to provide a large power supply system and a matching circuit, and the induction heating system as a whole is a large facility.

  Therefore, in the present invention, to provide an induction heating system and method capable of supplying power to a plurality of induction heaters from a single power supply system and freely setting a power supply time chart for each induction heater. Objective.

  In order to achieve the above object, an induction heating system according to the present invention includes an induction heater in which each secondary side of a high frequency current transformer and a low frequency current transformer is connected in parallel to a heating coil, and each induction heater. A high-frequency input switch connected to the primary side of the high-frequency current transformer of the heater, and a low-frequency input switch connected to the primary side of the low-frequency current transformer of each induction heater; A first power source that outputs high-frequency and low-frequency power by adjusting a ratio of the high-frequency and low-frequency output times to the output cycle, and a power having a frequency different from the frequency of the power output from the first power source. A second power source for output, a first power source output switch connected to the low frequency output terminal of the output terminals of the first power source, and a second power source connected to the output terminal of the second power source. Power output switch and high frequency input switch for each induction heater At least one of the induction heaters, the first power source, and the second power source are controlled by controlling the low frequency input switch and the first power output switch and the second power output switch. A switching control unit that connects either one or both of the power supplies, and each induction heater turns on one of the first power output switch and the second power output switch A heater control unit that requests the switching control unit to turn off the other and a command to switch the high-frequency input switch and the low-frequency input switch to either ON or OFF, respectively. Have.

  In the above configuration, when the switching control unit receives a command from each induction heater, the first power supply output switcher, the second power supply output switcher, and the induction heater that outputs the command in accordance with the command The high-frequency input switch and low-frequency input switch connected to the switch are controlled, and when the switching control unit finishes the control corresponding to the command from each induction heater, a switch completion signal is sent to the induction heater. When each of the induction heaters receives the switching completion signal from the switching control unit, the induction heating machine controls the outputs of the first power source and the second power source.

  In order to achieve the above object, an induction heating method of the present invention includes a plurality of induction heaters having heating coils, and a high frequency and low frequency power by adjusting a ratio of a high frequency and a low frequency output time to an output cycle. A first power source that outputs power, a second power source that outputs power having a frequency different from the frequency of the power output from the first power source, and switching means, and one frequency from the first power source. The first switching mode for receiving the power supply having the second switching mode, the second switching mode for receiving the power supply from the second power source, and the third switching mode for receiving the power of the different frequency from the first power source in a time-sharing manner And a plurality of fourth switching modes for receiving the power having one frequency from the first power source and the power from the second power source and superimposing both powers to be supplied. Any induction heater out of induction heaters By switching the switching means to induction heating the workpiece arranged in any of the induction heater.

  According to the present invention, since the power supply system that outputs a plurality of frequencies is complete, it is possible to simultaneously output a high frequency and a low frequency from the power supply system to the induction heater or alternately. Therefore, it is possible to select a low frequency component and a high frequency component in an arbitrary ratio in the electric power supplied from the power supply system to the induction heater, and thereby the frequency output from the power supply system is, for example, f1, f2, Even if it is f3, the same effect (this will be called "frequency effect") as the induction heating by the frequency of a value different from f1, f2, f3 is acquired. In addition, since a plurality of induction heaters are powered by a single power supply system, the system can be made compact.

It is a block diagram of the induction heating system which concerns on embodiment of this invention. It is a figure which shows typically the waveform output from the 1st power supply in FIG. It is a circuit diagram between a power supply system and a heating coil in the induction heating system shown in FIG. It is another circuit diagram between a power supply system and a heating coil in the induction heating system shown in FIG. It is a figure which shows typically the signal waveform which carries out output control from the 1st power supply shown in FIG. It is a schematic side view which shows the arrangement configuration of the induction heater shown in FIG. It is a schematic side view which shows the lower support part of the induction heater shown in FIG. (A) is a partial top view which shows the base plate in the induction heater shown in FIG. 6, and the rear end vicinity of a trolley | bogie, (b) is a partial side view of a trolley | bogie. FIG. 7 is a partial rear view showing the vicinity of the rear end of the base plate and the carriage in the induction heater shown in FIG. 6. FIG. 7 is a partial side view showing the vicinity of the front end of the base plate and the carriage in the induction heater shown in FIG. 6, (a) shows a situation where a low-frequency current transformer is installed on the gantry, and (b) shows (a). (C) is a figure which shows the condition where the low frequency current transformer is mounted on the carriage plate and is carried out while the low frequency current transformer is transferred to the carriage from the state. It is a figure which shows the state which has arrange | positioned the high frequency feed path and the low frequency feed path in the flame | frame of a duct, (a) is sectional drawing, (b) is a top view. The structure of each switch in the induction heating system of FIG. 1 is shown, (a) is a top view, (b) is a front view. It is a figure which shows the sequence in which each induction heater induction-heats a workpiece | work by the induction heating system of FIG. 1, Comprising: The case where a 1st induction heater receives electric power supply from a 1st power supply by a time division system, and shows the case where it heat-processes. ing. It is a figure which shows the sequence in which each induction heater induction-heats a workpiece | work by the induction heating system of FIG. 1, Comprising: The 1st induction heater receives electric power feeding from a 1st power supply and a 2nd power supply by a superposition method, and is heat-processed Shows when to do. It is a time chart which shows how many induction heaters can be supplied using one power supply system, (a) is two induction heaters, (b) is three (C) shows the case where five induction heaters are used. The example of the condition setting screen used when setting the heating condition from each induction heater to the system control unit including the switching control unit is shown, (a) shows an example of step condition setting, and (b) shows the time. FIG. 4C is a diagram illustrating a setting table for the division method 1, FIG. 5C is a setting table for the time division method 2, and FIG. It is a figure which shows the example of an output monitoring screen. It is a figure for demonstrating the 1st output monitoring method. It is a figure for demonstrating the 2nd output monitoring method, (a) shows a DC voltage and a time change of an electric current, (b)-(e) is DT signal, low frequency integrated electric energy, and high frequency, respectively. It is a figure which shows the time change of integrated electric energy and a heating signal. It is a block block diagram of an output monitoring apparatus. It shows a case where electric power is supplied by the superposition method, and is a diagram showing in time series whether or not there is an output of the first frequency and whether or not there is an output of the second frequency.

  Hereinafter, an induction heating system according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Overall configuration of induction heating system]
FIG. 1 is a configuration diagram of an induction heating system according to an embodiment of the present invention. As shown in FIG. 1, the induction heating system 1 according to the embodiment of the present invention includes a power supply system 20 including a plurality of induction heaters 10, a first power supply 21 and a second power supply 26, and a power supply system 20. Switching means 30 that is interposed between each of the induction heaters 10 and switches the connection. The switching means 30 includes a first power output switch 31 connected to the first power supply 21, a second power output switch 32 connected to the second power supply 26, and each induction heater 10. The high-frequency input switch 33 and the low-frequency input switch 34 are connected to the input side. In FIG. 1, the plurality of induction heaters 10 are shown as three, but may be two, four or more, or one. Hereinafter, the configuration of each unit will be described taking the case of three units as an example.

[Induction heater]
In FIG. 1, the induction heater 10 includes first, second, and third induction heaters 10A, 10B, and 10C. The induction heater 10 is a high-frequency current transformer 11 and a low-frequency generator. A current transformer 12, a heating coil 13, and a heater controller 14 are provided.

  Each of the high-frequency current transformer 11 and the low-frequency current transformer 12 includes a primary winding and a secondary winding. The turn ratio differs depending on whether the induction heater 10 is for high frequency or low frequency. Both the high-frequency current transformer 11 and the low-frequency current transformer 12 may have a core such as an iron core. The high frequency current transformer 11 may be an air core without a core. Whether or not the high-frequency current transformer 11 includes a core may be different for each induction heater 10.

  The secondary windings of the high-frequency current transformer 11 and the low-frequency current transformer 12 are connected in parallel to the heating coil 13. Here, the shape and dimensions of the heating coil 13 are selected depending on the work to be induction-heated for each induction heater 10. Therefore, the inductance of the heating coil 13 is different for each heating coil 13.

[Power supply system]
The power supply system 20 includes a first power supply 21 and a second power supply 26.
The first power supply 21 outputs power of different frequencies by changing the ratio of the high frequency and low frequency output times to the output period. The first power supply 21 alternately outputs a high frequency of, for example, 200 kHz and a low frequency of, for example, 10 kHz in a short time. The first power supply 21 adjusts the output ratio between the high frequency and the low frequency between 0 and 100% during a certain time (referred to as “output cycle”) T. FIG. 2 is a diagram schematically showing a waveform output from the first power supply 21. The horizontal axis represents time, and the vertical axis represents the low frequency occupancy DT and the output intensity. As shown in FIG. 2, in an output cycle T of, for example, 100 milliseconds, a low frequency is output at time t _L and a high frequency is output at time t _H. The low frequency occupancy is the voltage and current output from the first power supply 21 in the output cycle, and when only low frequency is output, the low frequency occupancy is 100%, and only high frequency is output. Is a low frequency occupation ratio of 0%. The output period T is the sum of t _L and t _H, and the ratio t _L / T of the time t _L during which only a low frequency is output with respect to the output period T is called the output ratio, and t _L / T is set from 0. It can be arbitrarily set within the range of 1. This output ratio is a low frequency duty ratio. The high frequency duty ratio is defined as a value obtained by subtracting the low frequency duty ratio from 1. Therefore, the output ratio may be set to 0% and the first power supply 21 may output only a high frequency, or the output ratio may be set to 100% and the first power supply 21 outputs only a low frequency. May be.

  The second power supply 26 outputs power having a frequency different from the output frequency of the first power supply 21. For example, low frequency power of 3 kHz and 8.5 kHz is output. In this way, the induction heater 10 may be fed only from the second power source 26, or the high frequency is output from the first power source 21 and only the low frequency is output from the second power source 10. The heating coil may be fed with a combined wave of high and low frequencies.

  In the embodiment of the present invention, since the first power source 21 and the second power source 26 supply power to the induction heater 10 at different frequencies, it is possible to heat from the work surface to different temperatures and to different temperatures. it can. Further details will be described later.

[Switching means]
The switching means 30 switches the connection between the power supply system 20 of the first power supply 21 and the second power supply 26 and each induction heater 10 and includes a plurality of switches. The switching means 30 includes a first power output switch 31 connected to the low frequency output terminal of the first power supply 21 and a second power output switch connected to the output terminal of the second power supply 26. The high frequency input switching device 33 and the low frequency input switching device 34 in each induction heater 10 are provided, and the switching control unit 35 comprehensively controls the ON / OFF control of the switching devices 31 to 34. Do.

  In each induction heater 10, the high frequency input switch 33 is connected to the primary winding of the high frequency current transformer 11, and the low frequency input switch 34 is connected to the primary winding of the low frequency current transformer 12. The The switching control unit 35 includes a first power supply side output switch 31, a second power supply side output switch 32, and a high frequency side input switch 33 and a low frequency side input switch 34 in each induction heater 10. Control.

[Method of feeding power from the power supply system to each induction heater by switching means]
As is conventionally known, due to the skin effect, eddy current flows from the surface of the workpiece to a deep region at a low frequency, and eddy current flows only near the surface of the workpiece, that is, a shallow region at a high frequency. Based on such an effect, the depth of the hardened layer can be controlled by the difference in frequency in various induction heat treatments such as quenching and tempering. In the present specification, this effect is referred to as a frequency effect. When the induction heat treatment is actually performed, a power source that outputs an appropriate frequency so as to obtain an optimum thickness of the hardened layer is selected.

In the induction heating system shown in FIG. 1, by providing a power supply system 20 that combines two types of power supplies, that is, a first power supply 21 and a second power supply 26, only the first power supply 21 is used in a time-sharing manner. It is also possible to supply power by a so-called superposition method in which the high frequency output from the first power supply 21 and the low frequency output from the second power supply 26 are superposed and supplied to the heating coil 13. When the time division method is used, the output ratio between the high frequency f _H and the low frequency f _L output from the first power supply 21 is controlled. Therefore, the effect of induction heating by the frequency f (f _L <f <f _H ) between the high frequency f _H and the low frequency f _L (hereinafter, this effect will be referred to as “frequency effect”) is obtained. It is done. In the case of using the superposition method, the power ratio between the high frequency output from the first power supply 21 and the low frequency output from the second power supply 26 is controlled. Therefore, an induction heating effect is obtained with a frequency between a high frequency and a low frequency. That is, the single power supply system 20 has a multi-frequency power supply function regardless of the time division method or the superposition method.

  By switching on the high-frequency input switch 33 and the low-frequency input switch 34 in an arbitrary induction heater 10 among the plurality of induction heaters 10 in the switching means 30, specific induction heating is performed from the power supply system 20. The machine 10 can be powered. Therefore, the single power supply system 20 can supply power to each induction heater 10 according to the heating conditions.

  In the embodiment of the present invention, since the power supply system 20 that outputs a plurality of frequencies is provided in this way, high frequency and low frequency can be output from the power supply system 20 to the induction heater 10 simultaneously or alternately. You can also Therefore, it is possible to select a low frequency component and a high frequency component in the electric power supplied from the power supply system 20 to the induction heater 10, and to obtain a frequency effect by induction heating.

  Moreover, as shown in FIG. 1, any one or a plurality of induction heaters 10 are connected to a single power supply system 20 by connection switching by the switching control unit 35, and pass through the switching control unit 35. Then, for example, various parameters such as frequency selection, output ratio adjustment, and high and low frequency intensities are set. Therefore, induction heating can be performed so that each induction heater 10 has an optimum frequency effect. By using the single power supply system 20, the utilization rate of the power supply system 20 is improved, and space saving and efficient induction heating with an optimum frequency have an energy saving effect.

  Here, each induction heater 10 is provided with a heater controller 14, and the heater controller 14 is connected to a switching controller 35. The switching control unit 35 includes a power control unit 21x of the first power supply 21, a power control unit 26x of the second power supply 26, a first power output switch 31, a second power output switch 32, and each induction heating. The high frequency input switch 33 and the low frequency input switch 34 connected to the machine 10 are connected. Therefore, the signals of the first power supply 21 and the second power supply 26 and the heater control unit 14 of each induction heater 10 are all input to the switching control unit 35. The first power source 21, the second power source 26, the heater controller 14 of each induction heater 10, the high frequency input switch 33 and the low frequency input switch 34 connected to each induction heater 10 All the command signals are output by the switching control unit 35. Therefore, the switching control unit 35 may be called a system control unit.

[Electric circuit configuration in the induction heating system shown in FIG. 1]
Next, in the induction heating system 1 shown in FIG. 1, the switching control unit 35 turns on the first power output switch 31 and turns off the second power output switch 32, so that the first induction heater The case where the high frequency input switch 33 and the low frequency input switch 34 in 10A are turned ON, and the high frequency input switch 33 and the low frequency input switch 34 in the other induction heaters 10B and 10C are turned OFF. For example, the circuit configuration between the power supply system 20 and the heating coil 13 will be described in more detail. Even when the high-frequency input switch 33 and the low-frequency input switch 34 in a specific induction heater 10B, 10C other than the first induction heater 10A are turned on, the circuit configuration is as follows. It is the same. However, since the distance of the power supply path between the power supply system 20 and the induction heater 10 is different for each induction heater 10, the inductance of the power supply path is different, and this matter is fed to simplify the explanation. We will not touch on the difference in circuit constants.

  FIG. 3 is a circuit diagram between the power supply system 20 and the heating coil 13 in the induction heating system shown in FIG. However, it shows that the first power output switch 31 and the high frequency input switch 33 and the low frequency input switch 34 in any given induction heater are in the ON state. The first power supply 21 as the power supply system 20 includes a high frequency output terminal and a low frequency output terminal. The primary side of the high frequency current transformer 11 is connected to the high frequency output terminal. A low frequency current transformer 12 is connected to the low frequency output terminal. The heating coil 13 is connected in parallel to each secondary side of the high-frequency current transformer 11 and the low-frequency current transformer 12.

  The first power supply 21 includes a conversion unit 21a that converts commercial power supplied from the commercial power supply 2 into direct current, and an inverse conversion unit 21b that converts direct current output from the conversion unit 21a into a predetermined frequency. The conversion unit 21a and the reverse conversion unit 21b are both controlled by an inverter control unit 21c as a power supply control unit 21x. In particular, the reverse conversion unit 21b converts a direct current into a specified frequency by a control signal from the inverter control unit 21c. A high-pass filter 21d and a low-pass filter 21e are connected in parallel to the inverse conversion unit 21b, a high-frequency output terminal is provided on the output side of the high-pass filter 21d, and a low-frequency output terminal is provided on the output side of the low-pass filter 21e. Is provided.

  In the high frequency current transformer 11, a transformer is constituted by the primary winding 11a and the secondary winding 11b. In the illustrated case, the secondary winding 11b has two coils 11d and 11e connected in series. A capacitor 11c is interposed between the coil 11d and the coil 11e. The capacitor 11c has a small impedance for high frequencies and a large capacitance for the low frequency, so that the power is supplied to the coil 13 with a good balance between high frequency and low frequency. Can be thrown in.

  In the low frequency current transformer 12, a transformer is constituted by the primary winding 12a and the secondary winding 12b. In the figure, a plurality of taps 12c are attached to the primary winding 12a so that the number of turns can be adjusted. A core 12d such as an iron core is provided so that the primary winding 12a and the secondary winding 12b can be easily induced by the core 12d such as an iron core. Further, bus bars are connected to both ends of the secondary winding 12 b, and each bus bar is connected to the heating coil 13. In FIG. 3, the bus bars are shown as inductances 12e and 12f. The inductances 12e and 12f constitute a kind of filter so that no high frequency is input from the high frequency current transformer 11 to the low frequency current transformer 12.

  As described above, the high-frequency current transformer 11 and the low-frequency current transformer 12 not only have a transformer with a primary winding and a secondary winding, but also between the heating coil 13 and the power supply system 20. A matching circuit for impedance matching is provided. Further, since the high frequency current transformer 11 and the low frequency current transformer 12 are connected in parallel to the heating coil 13, even if a low frequency flows from the secondary side of the high frequency current transformer 11, the secondary winding Each filter circuit is provided so that it is not input to the secondary winding 12b even if a high frequency flows from the secondary side of the low frequency current transformer 12. Therefore, each current transformer may be called a regulation circuit including a transformer, a matching circuit, and a filter circuit.

  FIG. 4 is another circuit diagram between the power supply system 20 and the heating coil 13 in the induction heating system shown in FIG. However, the case where the second power output switch 32 and the high frequency input switch 33 and the low frequency input switch 34 in any given induction heater are in the ON state is shown.

  The circuit shown in FIG. 4 differs from the circuit shown in FIG. 3 in that the second power supply 26 is connected to the low frequency current transformer 12 via the second power supply output switch 32. For example, as shown in FIG. 4, the second power supply 26 has a circuit configuration similar to that of the first power supply 21, but a conversion unit 26 a and an inverse conversion unit by an inverter control unit 26 c serving as a power supply control unit 26 x. Among the controls of 26b, the control of the inverse converter 26b is different in that it is configured to always output power of a specific frequency.

[Arrangement of high-frequency current transformer and low-frequency current transformer]
In the system configuration shown in FIG. 1, each induction heater 10 includes a high-frequency current transformer 11 and a low-frequency current transformer 12. As described above, the high-frequency current transformer 11 does not have a core, whereas the low-frequency current transformer 12 has a core. The reason why the high-frequency current transformer 11 does not have a core is that a high-frequency transformer has a higher voltage applied to the primary side of the transformer than a low-frequency transformer, so that a cored transformer capable of withstanding the high voltage can be easily manufactured. Because it is difficult.

  Usually, since the core is composed of an iron core or the like, the low frequency current transformer 12 is heavier than the high frequency current transformer 11. Therefore, when the high-frequency current transformer 11 and the low-frequency current transformer 12 are arranged up and down, the low-frequency current transformer 12 having a core is arranged on the lower side, and the high-frequency current transformer is placed thereon. A container 11 is arranged (see FIG. 6). Thereby, the dimension in the planar view of the induction heater 10 can be made small compared with the case where the high frequency current transformer 11 and the low frequency current transformer 12 are arranged side by side. In particular, as shown in FIG. 1, when a plurality of induction heaters 10 are fed by a single power supply system 20, the distance between the power supply system 20 and the induction heater 10 is preferably as short as possible. In this way, since the connection wiring between the power supply system 20 and the induction heater 10, for example, the bus bar is short, it is less necessary to consider the influence of the inductance component due to the connection wiring. Moreover, a voltage drop can be suppressed from the power supply system 20 to the induction heater 10.

[Necessity to replace the current transformer for low frequency part 1]
In the induction heating system 1 according to the embodiment of the present invention, the heating coil 13 is designed in accordance with the shape and size of the workpiece heating region, and the heating coil 13 is installed in the induction heater 10 so that the workpiece heating conditions are satisfied. In response, select whether to combine the frequencies, the size of the frequency, etc. In addition, in order to induction-heat workpieces of different types, each induction heater 10 is provided with a heating coil 13 designed according to the heating conditions for each workpiece, and is set for each induction heater 10 by a single power supply system 20. Electric power is supplied from the power supply system 20 according to the heating conditions. Therefore, the heating coil 13 is different for each induction heater 10.

  As described above, when the high-frequency current transformer 11 includes the primary winding 11a and the secondary winding 11b but does not include a core such as an iron core, the output of the high-frequency current transformer 11 is output. A change in impedance of the heating coil 13 connected to the terminal side is hardly transmitted to the power supply system 20 side. Therefore, when the heating coil 13 has a high impedance, the load-side impedance change as seen from the power supply system 20 side does not increase.

  However, the low-frequency current transformer 12 includes a primary winding 12a and a secondary winding 12b, and a core 12d such as an iron core is provided to improve the coupling between the primary winding 12a and the secondary winding 12b. I have. Therefore, when the heating coil 13 connected to the output terminal side of the low frequency current transformer 12 is replaced, a change in impedance of the heating coil 13 is easily transmitted to the power supply system 20 side. Therefore, when the heating coil 13 has a high impedance, the impedance on the load side viewed from the power supply system 20 side becomes high, and it is difficult to achieve impedance matching.

  Therefore, when the heating coil 13 is replaced, it may be necessary to replace the low frequency current transformer 12 having a different turn ratio between the primary winding 12a and the secondary winding 12b. In this regard, in the low frequency current transformer 12, as shown in FIG. 3, it is conceivable to increase the adjustment range of the turns ratio by providing a number of taps in the primary winding 12a. However, when a large number of taps are provided in the primary winding 12a, for example, in a transformer in which taps are provided from 4T to 8T depending on the number of turns, if the work that can be matched with the 4T tap is induction-heated, the voltage applied to 4T Is twice as high as that of the 8T tap. The voltage applied to the primary winding 12a is a very high voltage of, for example, 4000 V at the maximum depending on the matching conditions. Therefore, when this voltage is applied to the 4T tap, a voltage of 8000 V is generated in the 8T tap. In addition, since the output of the first power supply 21 is very large at 600 kW at the maximum, there is a high possibility that a dielectric breakdown such as a spark will occur. Therefore, it is not practical to provide many switching taps in the primary winding of the low frequency current transformer 12.

[Necessity to replace low-frequency current transformer 2]
When a high frequency and a low frequency are alternately supplied from the power supply system 20 to the heating coil 13 in a time division manner, the low frequency may be difficult to achieve impedance matching as compared with the high frequency. FIG. 5 is a diagram schematically showing signal waveforms that are output-controlled from the first power supply 21 shown in FIG. The horizontal axis is time, and the vertical axis is signal intensity. 5, (a) is a waveform of ON / OFF of output from the first power supply 21, (b) is a waveform of low frequency occupancy, (c) is a waveform of the DC voltage Vdc in the first power supply 21, ( d) is a waveform of the direct current Idc in the first power supply 21.

  When the output from the first power supply 21 is turned ON to alternately output a low frequency and a high frequency, the DC current Idc begins to increase when the low frequency output state transitions to the high frequency output state. Conversely, when a transition is made from the high-frequency output state to the low-frequency output state, the DC current Idc begins to decrease. Regarding the impedance of the load viewed from the power supply side 20, for example, as shown in the figure, when the high frequency impedance is smaller than the low frequency impedance, that is, when the high frequency is greatly different from the low frequency, the high frequency and the low frequency are Since Idc increases and decreases as shown in the figure, it is desirable to adjust the impedances viewed from the high-frequency and low-frequency power sources to the same extent. For this adjustment, it is necessary to replace the low frequency current transformer.

[Configuration of each part of induction heater]
Therefore, in the embodiment of the present invention, a mechanism for replacing the low frequency current transformer (hereinafter, referred to as an exchange mechanism) can be provided, for example, as a retrofit. As a premise for explaining the exchange mechanism, the high-frequency current transformer 11, the low-frequency current transformer 12, the heating coil 13 in the induction heater 10, and a power supply path (hereinafter referred to as “power transmission bus bar”) The arrangement configuration etc. will be described.

[Configuration of induction heater as a whole]
FIG. 6 is a schematic side view showing the arrangement of the induction heater. In the induction heater 10, as shown in FIG. 6, the low-frequency current transformer 12 and the high-frequency current transformer 11 are placed on and supported by the gantry 80. The low-frequency current transformer 12 and the high-frequency current transformer 11 are connected to a switcher not shown in FIG. 6 via primary bus bars 81 and 83, respectively, and the heating coil 13 via the secondary bus bar 82. Are connected in parallel. Below, it demonstrates supposing the hardening machine which heats a workpiece | work and quenches rapidly.

  In FIG. 6, the frame 80 is originally not provided with a mechanism for replacing the low-frequency current transformer 12, and the low-frequency current transformer 12 disposed on the rack 80 can be replaced. An exchange mechanism 90 constructed by assembling various members retrofit is shown. As another replacement mechanism, a roller is provided at the lower ends of both side surfaces of the low-frequency current transformer 12 so that the low-frequency current transformer 12 can be pulled out backward (to the left in FIG. 6). When a guide member such as a rail for guiding the frequency current transformer 12 to the back is attached to the gantry 80, a simpler exchanging mechanism than the exchanging mechanism 90 described later with reference to FIGS. 6 to 10 is used. Assembled into.

[Heating coil]
The heating coil 13 is supported by being connected to a plate-like secondary bus bar 82 connected to the high-frequency current transformer 11 and the low-frequency current transformer 12. In the induction heater 10, a heating coil 13 having a shape and dimensions corresponding to the heating area of the workpiece can be selected and mounted. The induction heater 10 is provided with a quenching liquid spray nozzle 84 for spraying a quenching liquid after induction heating.

[Current transformer]
The high frequency current transformer 11 has a primary winding and a secondary winding as described above. The primary winding and the secondary winding of the high-frequency current transformer 11 are provided with liquid passages, respectively, so that a coolant from a coolant system (not shown) can pass therethrough.

  The low-frequency current transformer 12 has a primary winding, a secondary winding, and a core as described above. The core couples the primary and secondary windings. In the present embodiment, a plurality of low-frequency current transformers 12 having different numbers of turns of the primary winding and the secondary winding are prepared, and those satisfying the impedance matching condition corresponding to the heating coil 13 are prepared. Select and place on the gantry 80. The primary winding and the secondary winding of the low frequency current transformer 12 are also provided with a liquid passage, so that a coolant from a coolant system (not shown) can pass therethrough.

  A connecting portion 86 is provided on the rear end surface of the low frequency current transformer 12, and the primary bus bar 83 is detachably connected to the connecting portion 86. A connecting portion 87 is provided at the front end of the low frequency current transformer 12, and the secondary bus bar 82 is detachably connected to the connecting portion 87. The liquid passages of the primary winding and the secondary winding of the low frequency current transformer 12 are connected to the coolant system via a coupler and can be separated by the coupler. The coupler has a structure in which the internal valve closes the flow path when the connection is released and separated.

[Stand]
The gantry 80 is formed in a hollow three-dimensional shape using an angle steel material or the like. The gantry 80 is provided with an upper support portion 88 that supports the high-frequency current transformer 11 at the upper portion and a lower support portion 89 that supports the low-frequency current transformer 12 under the upper support portion 88. . The heating coil 13 is disposed in front of the upper support portion 88 and the lower support portion 89. The front side surfaces of the upper support portion 88 and the lower support portion 89 are covered with a cover member 91 for partitioning from the heating position. The gantry 80 is not limited to the illustrated shape as long as it has such a configuration.

[Exchange mechanism]
As described above, when a simple exchange mechanism is attached to the gantry 80, it is sufficient to use the exchange mechanism. When such a replacement mechanism is not provided in the gantry 80, the following replacement mechanism is provided.

  As shown in FIG. 7, an exchange mechanism 90 for exchanging the low frequency current transformer 12 is assembled and constructed in the lower support portion 89. Such a retrofitting replacement mechanism 90 includes a front-rear direction support portion 92 that is fixed to the gantry 80 and extends in the front-rear direction, a base plate 93 that is supported on the front-rear direction support portion 92 so as to be displaceable back and forth, and a base plate 93 is provided with a carriage 94 that can move back and forth on the running surface on 93. Originally, in the gantry 80 that is not provided with an exchange mechanism, when the low frequency current transformer 12 is arranged on the gantry 80 as shown in FIG. 10A, the pallet 80 is replaced with another low frequency current transformer. The operator inserts the base plate 93 between the low-frequency current transformer 12 and the front-rear direction support portion 92, and displaces the base plate 93 to the front side. Then, the base plate 93 rides on the inclined member 96 attached to the front side of the front base 80, and the base plate 93 slightly rises (FIG. 10B). As will be described later, the operator raises the rear end of the carriage plate 94b by the vertical movement displacement means 97, makes the carriage plate 94b horizontal, and floats the low frequency current transformer 12 from the gantry 80 to be supported by the carriage plate 94b. (FIG. 10C), the low frequency current transformer 12 is slid backward together with the carriage 94.

  The front-rear direction support portion 92 may be a member such as a frame member that constitutes the gantry 80, or may be a member such as a plate fixed to the gantry 80. The front-rear direction support portion 92 may be any member that has sufficient strength to support the low-frequency current transformer 12 and can stably support the base plate 93. The base plate 93 has a strength capable of supporting the low frequency current transformer 12, and has a running surface 93a of the carriage 94 on the upper surface as shown in FIGS. Base ribs 93c extending in the front-rear direction substantially parallel to each other are provided on the left and right side edges of the upper surface of the base plate 93. By providing the base rib 93c, the base plate 93 is ensured in strength and thinned.

  As shown in FIGS. 8 and 9, a pair of side edge guide portions 80 a are fixed to the frame 80 so as to extend in the front-rear direction along the left and right side edges of the base plate 93. Originally, the low frequency current transformer 12 is supported by a pair of side edge guide portions 80a in a gantry that is not provided with an exchange mechanism. The base plate 93 is disposed between the pair of side edge guide portions 80 a and is placed on the front-rear direction support portion 92. Since the outer surfaces of the left and right base ribs 93c can slide in opposition to the inner surface of the side edge guide portion 80a, the base rib 93c is guided by the side edge guide portion 80a and the base plate 93 is displaced back and forth. It is possible. Although not particularly limited, the base plate 93 is preferably arranged horizontally.

  Front displacement means 95 are provided on the left and right sides of the rear end side of the base plate 93. The front displacement means 95 connects the base plate 93 and the gantry 80, and the base plate 93 can be displaced back and forth with respect to the gantry 80. The front displacement means 95 includes a fixed block 95a fixed to the left and right bases 80 on the rear end side of the base plate 93, and a base projecting left and right from the rear end of the base plate 93 and facing the rear side of the fixed block 95a. The protrusion part 93b and the pushing screw part 95b fixed to the fixed block 95a and arrange | positioned through the base protrusion part 93b are provided. In the forward displacement means 95, by rotating the screwing member 95c of the pushing screw portion 95b, the base protruding portion 93b can be pressed to advance the base plate 93.

  As shown in FIG. 10, an inclined member 96 is provided and fixed on the front-rear direction support portion 92 at a position corresponding to the front end side of the base plate 93 in the gantry 80. The inclined member 96 has a gradient in which the front becomes higher. As the inclined member 96, a wedge-shaped plate extending in the entire left and right width of the lower support portion 89 is used. When the base plate 93 is advanced by the front displacement means 95, the front end side of the base plate 93 rides on the inclined member 96, and the front end side of the base plate 93 can be raised with respect to the front-rear direction support portion 92 according to the advancement amount.

  As shown in FIGS. 7 and 8, the vertical displacement means 97 is provided on the rear end side of the base plate 93, whereby the rear end side of the base plate 93 is displaced vertically with respect to the gantry 80. The vertical displacement means 97 is composed of, for example, a plurality of screw members screwed to the rear end side of the base plate 93. The base plate 93 can be raised from the front-rear direction support portion 92 of the gantry 80 by screwing each screw member.

  As shown in FIGS. 7 to 9, the carriage 94 includes a plate-like carriage plate 94b, a plurality of rollers 98 that are arranged in a row in the front-rear direction on the left and right edges of the lower surface of the carriage plate 94b, and are freely rollable. A handle 94a that protrudes from the upper surface and is fixed to the rear end side of the carriage plate 94b is provided. On the lower surface of the carriage plate 94b, a pair of carriage ribs 94c extending in the front-rear direction along the rows of the left and right rollers 98 are provided, and the carriage plate 94b is thinned by securing the strength of the carriage plate 94b. There are at least three rollers 98 on each side of the carriage 94, and preferably more rollers 98 are arranged in parallel to each other. By disposing many rollers 98, the weight of the low frequency current transformer 12 can be distributed and loaded on each roller 98. Each member of the carriage 94 is fixed with bolts and screws and is not welded. As a result, the carriage 94 is prevented from being distorted and can operate stably in a narrow space.

  The carriage plate 94b is formed in a flat plate shape, and cam followers 94d that roll in contact with the inner side surfaces of the left and right base ribs 93c are disposed on the left and right front end sides and rear end sides of the carriage plate 94b, respectively. . A number of rollers 98 roll on the running surface 93a of the base plate 93, and the cam follower 94d rolls in contact with the inner side surface of the base rib 93c. Accordingly, the carriage 94 can move back and forth along the base rib 93 c on the base plate 93.

  As shown in FIG. 8, a jig 99 for locking the front end edge of the low frequency current transformer 12 and a jig 99 for locking the rear end edge may be attached to the upper surface of the carriage plate 94b. The jigs 99 are for positioning the low-frequency current transformer 12 placed on the carriage plate 94b at predetermined positions, and are each formed in a bar shape and fixed so as to extend in the width direction of the carriage 94. On the side surface of the jig 99, a guide surface 99a for guiding the front end edge or the rear end edge of the low frequency current transformer 12 when the low frequency current transformer 12 is mounted is provided.

  The carriage plate 94b is provided with a plurality of fixing positions of the jig 99 at a plurality of positions. By selecting the fixing position and fixing the jig 99, it can be used for a plurality of low frequency current transformers 12 having different lengths in the front-rear direction. The jigs 99 are respectively fixed to the upper surface of the carriage 94 by jig fixing screws 99b. A jig fixing screw 99b of each jig 99 is eccentrically arranged on one side with respect to the center in the width direction of each jig 99, and the guide surface of each jig 99 is fixed by inverting the front and rear. The position of 99a can be changed in two ways. Thereby, the low frequency current transformer 12 having different lengths in the front-rear direction can be positioned and placed on the carriage 94 using the same jig 99.

  By moving the carriage 94 forward or backward with the low-frequency current transformer 12 positioned and mounted, the low-frequency current transformer 12 can be disposed at the connection position P1 with the heating coil 13 and moved backward. Can be arranged at the exchange position P2.

  As shown in FIGS. 10A and 10B, the gantry 80 at a position facing the front edge of the trolley 94 is provided with a trolley stopper 80 b that comes into contact with the trolley 94. The carriage stopper 80b can be arranged at the connection position with high accuracy by adjusting the protruding amount to adjust the contact position with the carriage 94.

  The cover member 91 provided on the front side of the lower support portion 89 has a size that covers the front of the lower support portion 89, and the front end surface of the low frequency current transformer 12 disposed at the connection position P1 is in contact with the cover member 91. It arrange | positions so that it may contact | adhere. In the center of the cover member 91, a connection opening 91a in which the connection portion 87 of the low frequency current transformer 12 is disposed is provided. A packing 91b surrounding the connection opening 91a is disposed around the connection opening 91a in an endless manner. By arranging the low frequency current transformer 12 at the connection position P1, the periphery of the connection portion 87 of the low frequency current transformer 12 is in close contact with the packing 91b. When the quenching liquid is sprayed at the heating position, the packing 91b can surely prevent the quenching liquid from entering the board. The crushing margin of the packing 91b is adjusted by adjusting the contact position of the carriage stopper 80b.

  Here, as shown in FIG. 6, in a state where the low frequency current transformer 12A is mounted on the gantry 80 that is not provided with an exchange mechanism, a case where the low frequency current transformer 12B is replaced with another. explain.

  In the gantry 80 not provided with the exchange mechanism, as shown in FIG. 6, the primary bus bar 83 is connected to the connection portion 86 on the rear side of the low frequency current transformer 12 </ b> A, and the secondary bus bar 82 is connected to the low frequency bus bar 82. The heating coil 13 is connected to the secondary bus bar 82, and is connected to the connecting portion 87 on the front side of the current transformer 12. The secondary winding of the high frequency current transformer 11 and the secondary winding of the low frequency current transformer 12 are connected in parallel to the heating coil 13. The primary side bus bar 83, the secondary side bus bar 82, and the primary winding and the secondary winding flow path of the low frequency current transformer 12 are connected to the coolant system by a coupler. Under such circumstances, the low frequency current transformer 12 and the primary bus bar 83 are disconnected, the low frequency current transformer 12 and the secondary bus bar 82 are disconnected, and the coupler of the coolant path is removed.

  As a result, the low-frequency current transformer 12A can be prepared for replacement. First, as shown in FIG. 10A, the inclined member 96 is arranged so as to increase from the rear toward the front near the cover member 91 on the front end side of the left and right front and rear direction support portions 92. At this time, as shown in FIG. 10A, the low-frequency current transformer 12B is supported by the angle of the gantry 80, specifically, the angle of the mounting support portion 80c at the upper end of the side edge guide portion 80a.

  Next, the base plate 93 is inserted between the low-frequency current transformer 12A and the longitudinal support portion 92, and the carriage 94 runs on the base plate 93. As shown in FIG. The carriage 94 is inserted between the low frequency current transformer 12 </ b> A and the base plate 93 until it abuts against 80. In this state, there is still a gap between the low frequency current transformer 12A and the carriage 94.

  Next, the front displacement means 95 is disposed on both the left and right sides of the rear end side of the base plate 93, and the front displacement means 95 is connected to the base plate 93 and the gantry 80. The screw member 95c of the forward displacement means 95 is rotated to displace the base plate 93 to the front side, and a large force is generated upward with a small force in the forward direction by utilizing the wedge effect due to the inclination of the inclined member 96. Thereby, when the base plate 93 is displaced to the front side, the base plate 93 gets on the inclined member 96 attached to the front side of the front base 80, and the base plate 93 is slightly raised.

  Thereafter, the rear end of the carriage plate 94b is raised by the vertical movement displacement means 97, the carriage plate 94b is leveled, and the low frequency current transformer 12A is floated from the mount 80 and supported by the carriage plate 94b (FIG. 10C). ), And slide the low frequency current transformer 12 together with the carriage 94 backward. At this time, since the extension plate 93d is disposed on the rear side of the base plate 93 so as to be smoothly continuous with the upper surface of the base plate 93, the extension plate 93d has a low frequency at an exchange position P2 that does not overlap the current transformer 11 for high frequency. The carriage 94 is moved and pulled out together with the current transformer 12A. Thereafter, with the carriage 94 stopped at the replacement position P2, the low frequency current transformer 12 is lowered from the carriage 94 by a crane (not shown), for example.

  Next, another low-frequency current transformer 12B is mounted on the carriage plate 94b using, for example, a crane (not shown), and the carriage 94 is advanced on the base plate 93. The carriage 94 is stopped by bringing the front end of the carriage plate 94b into contact with the carriage stopper 80b. Thereby, positioning in the front-rear direction is performed, and the low-frequency current transformer 12 can be arranged at the position of the connection position P1.

  Thereafter, in order to fix the carriage 94, the carriage 94 is fixed to the base plate 93 via the fixing member 94e by the fixing member 94e as shown in FIG.

  Here, the connection part 86 on the rear side of the low frequency current transformer 12B is positioned slightly higher than the primary bus bar 83 and the secondary bus bar 82 before the low frequency current transformer 12A is replaced. A connecting portion 87 on the front side of the current transformer 12B is disposed. Therefore, the positions of the primary bus bar 83 and the secondary bus bar 82 are adjusted by, for example, widening the mounting holes, and the respective bus bars are connected.

  As described above, the base plate 93, the inclined member 96, and the forward displacement means 95 can be left assembled, and the exchange mechanism 90 can be retrofitted to the gantry 80 by these and the carriage 94.

  After the retrofitting, when the low frequency current transformer 12 is replaced, it is only necessary to remove the fixing member 94e from the base plate 93 and to retract the carriage 94 on the base plate 93 and pull it out.

  Therefore, when performing the workpiece quenching process using the induction heater 10, the heating coil 13 corresponding to the workpiece and the quenching region is selected, and the low frequency current satisfying the impedance matching condition corresponding to the selected heating coil 13 is selected. The transformer 12 is selected. Even if the high frequency current transformer 11 is previously installed on the upper support portion 88 of the gantry 80, the selected low frequency current transformer 12 can be installed on the lower support portion 89.

  As shown in FIG. 6, the low frequency current transformer 12 and the high frequency current transformer 11 are arranged one above the other so that the arrangement space can be reduced. Moreover, since the low frequency current transformer 12 has a core and is heavier than the high frequency current transformer 11, the low frequency current transformer 12 is disposed under the high frequency current transformer 11. Thus, the center of gravity of the induction heater 10 can be lowered and the whole can be installed stably.

  In the induction heater 10, a low-frequency current transformer 12 and a high-frequency current transformer 11 are connected in parallel to the heating coil 13, and the low-frequency current transformer 12 and the high-frequency current transformer 11 are switched. It is connected to the power supply system 20 via a vessel. Therefore, by appropriately switching the switch, various heating effects can be realized, and appropriate heating according to the heating area of the workpiece can be realized.

  In particular, any one of a plurality of heating coils 13 having different impedances can be selected and attached to the secondary bus bar 82, and a plurality of low frequency currents having different numbers of turns of the primary winding and the secondary winding. A transformer that satisfies the impedance matching condition corresponding to the heating coil 13 can be selected. By exchanging the low frequency current transformer 12, the impedance matching condition corresponding to the heating coil 13 can be satisfied, and various heating effects corresponding to the workpiece can be efficiently realized.

  Here, the exchange mechanism 90 is not used only for each induction heater 10 in the induction heating system 1 as shown in FIG. 1, and can be used in the following cases. For example, even in the induction heater 10 having one current transformer, the current transformer cannot be attached or detached from the upper side of the apparatus because other members are disposed on the current transformer. In this case, the current transformer can be easily attached and detached by providing the exchange mechanism 90 as described above. If the current transformer breaks down, the current transformer can be pulled out from the gantry 80 for repair.

  In the induction heating system 1 shown in FIG. 1, since a single power supply system 20 supplies power to a plurality of induction heaters 10, the power supply system 20 to the induction heater 10, specifically, the induction heater 10 is attached. Power is supplied to the high frequency input switch 33 and the low frequency input switch 34 using a bus bar. Since the single power supply system 20 is not provided for each induction heater 10, the distance between each induction heater 10 and the single power supply system 20 cannot be shortened. Therefore, it is necessary to earn a distance by connecting bus bars. On the other hand, in the induction heating system 1 according to the embodiment of the present invention, the single power supply system 20 supplies high power with a high voltage on the order of several thousand volts. These points must also be taken into consideration in the way the bus bars are arranged. Hereinafter, it demonstrates in order.

[High-frequency feed line, Low-frequency feed line]
The high-frequency power supply path and the low-frequency power supply path are disposed in a duct in a case that accommodates a matching unit, a switch, a current transformer, and the like. FIGS. 11A and 11B are views showing a state where the high-frequency power supply path and the low-frequency power supply path are arranged in the duct frame, where FIG. 11A is a cross-sectional view and FIG. 11B is a plan view. The duct frame 51 is assumed to have a rectangular frame extending in the depth direction by the vertical frame 51a, the horizontal frame 51b, and the depth frame 51c. In the frame, one bus bar 52a and the other bus bar 52b are arranged with a space therebetween, whereby a high-frequency power supply path 52 is arranged, and one bus bar 53a and the other bus bar 53b are spaced apart. As a result, the low-frequency power supply path 53 is provided.

  As described above, since power is supplied to the plurality of induction heaters 10 by the single power supply system 20, the distance from the power supply system 20 to each induction heater 10 is increased. Therefore, the inductance in the bus bar pair is increased. Then, the influence of the bus bar inductance cannot be ignored in the circuit in which the power supply system 20, the current transformers 11 and 12, and the heating coil 13 are connected, and the resonance frequency is lowered. In particular, when a high frequency of about 200 kHz is supplied, reactance increases and a voltage drop increases in the supply path.

  Therefore, in the embodiment of the present invention, the bus bar is widened so that the inductance of the power transmission bus bar is as small as possible, and the distance between one bus bar 52a, 53a and the other bus bar 52b, 53b, That is, the interval between one bus bar 52a, 53a and the other bus bar 52b, 53b is reduced so as to make the gap as small as possible.

11A and 11B, a pair of high-frequency power transmission bus bars 52a and 52b and a pair of low-frequency power transmission bus bars 53a and 53b are arranged side by side between a pair of vertical frames 51a and 51a on the left and right. To do. At this time, in plan view, the interval L _H between the high-frequency power transmission bus bars 52a and 52b is larger than the interval L _L between the low-frequency power transmission bus bars, for example, L _H = 60 to 100 mm and L _L = 10 to 50 mm. . The reason _why L _H > L _L is that the high frequency voltage is larger than the low frequency voltage. In any power transmission bus bar, there are mounting hooks 52c, 52d, 53c, 53d which are called ears up and down. The power transmission bus bars 52a, 52b, 53a, 53b are fixed vertically to the horizontal frame 51b with the insulators 54 interposed between the mounting hooks 52c, 52d, 53c, 53d. One power transmission bus bar 52a, 52b, 53a, 53b is provided with mounting hooks 52c, 52d, 53c, 53d spaced apart from each other in the longitudinal direction, that is, in the arrangement direction.

In any of the power transmission bus bars 52a, 52b, 53a, and 53b, when the gaps L _L and L _H are increased, the interval between the high frequency power transmission bus bar 52b and the low frequency power transmission bus bar 53a is narrowed. Moreover, since a high voltage of several thousand volts is applied to any of the power transmission bus bars 52a, 52b, 53a, 53b, there is a possibility of causing dielectric breakdown. Accordingly, the bus bars 52b and 53a in which the pair of the high-frequency power transmission bus bars 52a and 52b and the pair of the low-frequency power transmission bus bars 53a and 53b face each other shift the mounting hooks 52d and 53c in the arrangement direction. Is provided.

  Further, any of the power transmission bus bars 52a, 52b, 53a, 53b is fixed to the horizontal frame 51b via the insulator 54, but the horizontal frame 51b is provided with an elongated hole 55 along the horizontal frame 51b. With the elongated hole 55, the interval between the horizontal frame 51b and the insulator 54, and consequently the power transmission bus bars 52a, 52b, 53a, 53b can be adjusted.

[Switcher]
In the induction heating system shown in FIG. 1, a first power output switch 31, a second power output switch 32, a high frequency input switch 33, and a low frequency input switch 34 are provided as switches. It has been. These switches have substantially the same configuration. 12 shows the configuration of each switch in the induction heating system shown in FIG. 1, (a) is a plan view, and (b) is a front view.

  In the switch 60, for example, the upstream bus bar mounting portion 61a and the downstream bus bar mounting portion 61b in one phase out of two phases of the U phase and the V phase are erected on the base plate 63, and the other The upstream bus bar mounting part 62a and the downstream bus bar mounting part 62b in the phase are erected on the base plate 63 so as to face each other. The upstream bus bar mounting portions 61a and 62a and the downstream bus bar mounting portions 61b and 62b have cooling passages (not shown) formed therein, and are connected to the cooling water inlet 64a and the cooling water discharge port 64b provided on the lower surface of the table. Communicate.

  In order to prevent dielectric breakdown between the upstream bus bar mounting portions 61a and 62a and the downstream bus bar mounting portions 61b and 62b, between the upstream bus bar mounting portions 61a and 62a and the downstream bus bar mounting portions 61b and 62b in the base plate 63. Are provided with long holes 63a and 63b to set a long creepage distance. Further, the upstream bus bar mounting portion 62a and the downstream bus bar mounting portion 61b in the base plate 63 are configured so as not to cause dielectric breakdown between the downstream bus bar mounting portion 61b of one phase and the upstream bus bar mounting portion 62a of the other phase. A long hole 63c is provided between them, and the creeping distance is set long.

  As described above, the upstream bus bar mounting portions 61a and 62a and the downstream bus bar mounting portions 61b and 62b are erected on the base plate 63 at intervals with respect to each phase. The bus bar mounting portions 61a, 61b, 62a, and 62b are brought into contact with the respective end faces, whereby the bus bar mounting portions are electrically connected to be switched between ON and OFF. For this reason, a connection block 65 is provided for each phase. As shown in the figure, the connection block 65 includes an abutment portion 65a that electrically connects the upstream busbar attachment portions 61a and 62a and the downstream busbar attachment portions 61b and 62b, and the abutment portion 65a that rotates about the vertical axis. The support portion 65b is movably supported, and the support portion 65b includes a rod 65c that extends on the opposite side of the contact portion 65a. A support block 66 is disposed on the base plate 63 so as to be displaceable to the left and right by an air cylinder 67 at positions facing the 61a and 62a and the downstream bus bar mounting portions 61b and 62b with the connection block 65 interposed therebetween. The rod 65c of the connection block 65 of each phase passes through one support block 66, and a compression spring 68 is attached to each rod 65c to urge the connection block 65. As shown in the drawing, the connection block 65 rotates around a vertical axis by a predetermined range. Therefore, when the support block 66 is displaced to one side by the air cylinder 67, each connection block 65 is displaced to one side accordingly, and each end face of the upstream bus bar mounting portions 61a, 62a and the downstream bus bar mounting portions 61b, 62b. The compression spring 68 is surely pressed against each other.

  On the base plate 63, cooling water is introduced into each connection block 65 to discharge the cooling water from the connection block 65, and air is injected into and discharged from the air cylinder 67. A solenoid valve 70 and a limit switch 71 for confirming the forward end and the reverse end of the air cylinder 67 are provided.

  A plurality of insulators 72 are attached to the lower surface of the base plate 63, and the switch 60 itself is electrically insulated. The connection block 65, the upstream bus bar mounting portions 61a and 62a, and the downstream bus bar mounting portions 61b and 62b are cooled with cooling water. For this reason, various detection sensors for detecting whether the flow rate of the cooling water exceeds a specified value or detecting an abnormality in the air cylinder or piping necessary for it are attached. When the air pressure abnormality and the cooling water flow rate abnormality are detected by the detection sensor, the switcher 60 transmits an air pressure abnormality signal and a cooling water flow rate abnormality signal to the switching control unit 35. Thereby, the switching control unit 35 instructs each induction heater or power supply system not to perform system operation.

[Method of heating multiple workpieces sequentially by induction heating system]
In the induction heating system 1 shown in FIG. 1, the induction heating system will be described in detail while explaining a method of sequentially heating the workpiece with each induction heater 10.

FIG. 13 is a diagram showing a sequence in which each induction heater 10 induction-heats a workpiece by the induction heating system 1 shown in FIG. 1, and in particular, the first induction heater 10 </ b> A is time-shared from the first power supply 21. The case where it heat-processes by receiving electric power supply is shown.
As ST <b> 1-1, the first induction heater 10 </ b> A transmits a switching request signal from OFF to ON to the switching control unit 35.
As ST1-2, when receiving the switching request signal from OFF to ON, the switching control unit 35 transmits a switching request signal from OFF to ON to the first power output switch 31.
As ST1-3, the first output switch 31 for power supply performs switching control from OFF to ON when receiving the switching request signal from OFF to ON.
As ST1-4, the first power output switch 31 transmits a switching completion signal to the switching controller 35 when the switching control from OFF to ON is completed.
As ST1-5, when the switching control unit 35 receives the switching request signal from OFF to ON, the switching control unit 35 receives the high frequency input switching unit 33 and the low frequency input switching unit 34 connected to the first induction heater 10A. Then, a request signal for switching from OFF to ON is transmitted.
As ST1-6, when the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater 10A receive the switching request signal from OFF to ON, switching control from OFF to ON is performed. I do.
As ST1-7, the high-frequency input switch 33 and the low-frequency input switch 34 connected to the first induction heater 10A transmit a switch completion signal to the switch controller 35.
As ST1-8, the switching control unit 35 starts from OFF from the first power output switch 31 and the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater 10A. When the switch completion signal to ON is received, the switch completion signal is transmitted to the first induction heater 10A.
As ST1-9, an output start signal is transmitted to the first power supply 21 when the first induction heater 10A receives the switching completion signal in ST1-8.
When receiving the output start signal in ST1-9, the first power supply 21 supplies power to the first induction heater based on the output control information received together with the output start signal. The output control information here is output control information notified to the first power supply 21, and as its item, for example, identification information on whether to output either high frequency or low frequency or only high frequency is output. When the frequency ratio can be set, the frequency value, the total output time, etc. can be mentioned.
As ST1-10, when the first power supply 21 finishes the power supply based on the output control information, the first power supply 21 transmits a power supply end signal to the first induction heater 10A.
As ST1-11, when the first induction heater 10A receives the power supply end signal, the first induction heater 10A transmits a switching request signal from ON to OFF to the switching control unit 35.
As ST1-12, when receiving the switching request signal from ON to OFF, the switching control unit 35 transmits the switching request signal from ON to OFF to the first power output switch 31. In addition, when the switching control unit 35 receives the switching request signal from ON to OFF, and the switching request signal is input from another induction heater, for example, the second induction heater 10B, the second control unit 35 According to the request of the induction heater 10B, the first power output switch 31, the second power output switch 32, the high frequency input switch 33 and the low frequency input switch 34 of the second induction heater 10B. Any one or a plurality of switches are switched. If the switching control unit 35 has not received a switching request signal from another induction heater, the state of the switch maintains the current state.
As ST1-13, when the first power output switch 31 receives a switching request signal from ON to OFF, it performs switching control from ON to OFF.
As ST1-14, the first power output switch 31 transmits a switching completion signal to the switching controller 35 when the switching control from ON to OFF is completed.
As ST1-15, when the switching control unit 35 receives the switching request signal from ON to OFF, the switching control unit 35 receives the high frequency input switching unit 33 and the low frequency input switching unit 34 connected to the first induction heater 10A. Then, a switch request signal from ON to OFF is transmitted.
As ST1-16, when the high frequency input switching device 33 and the low frequency input switching device 34 connected to the first induction heater 10A receive the switching request signal from ON to OFF, switching control from ON to OFF is performed. I do.
As ST1-17, the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater 10A transmit a switching completion signal to the switching control unit 35 when the switching is completed.
Here, ST1-2 and ST1-5 may be performed simultaneously, or time series may be mixed. ST1-12 and ST1-15 may be performed at the same time, or time series may be mixed.

In the sequence shown in FIG. 13, once the switching control unit 35 receives a switching request from the first induction heater 10 </ b> A to ON, a switching completion signal from ON to OFF in ST <b> 1-17 is received. Even if it receives a switching request signal from other induction heaters to ON until it is received, it receives a switching completion signal from ON to OFF by ST1-17 and receives a switching request signal from other induction heaters. The process which concerns on is performed.
As a result, even a single power supply system 20 can process a switching request from a plurality of induction heaters 10 without batting.

  In the sequence described with reference to FIG. 13, it is assumed that induction heating is performed using a plurality of induction heaters, but heat treatment is repeated with only one induction heater using the system shown in FIG. May be. In that case, the life of the switching device can be extended by keeping the output switching device connected to only the induction heater 10A. Note that the switch may be turned off each time there is no switching request signal from another induction heater.

The sequence shown in FIG. 13 is an example, and may be modified as follows, for example.
Instead of ST1-8 and ST1-9 in FIG. 13, the switching control unit 35 includes a first power output switch 31 and a high frequency input switch 33 and a low frequency connected to the first induction heater 10A. When a switch completion signal from OFF to ON is received from the input switch 34, an output start signal is transmitted directly to the first power supply 21. When receiving the output start signal from the switching control unit 35, the first power supply 21 supplies power to the first induction heater 10A based on the output control information received together with the output start signal. The items of the output control information are the same as described above.
In place of ST1-10 and ST1-11 in FIG. 13, when the first power supply 21 finishes the power supply based on the output control information, the switching control unit 35 turns the first power supply output switch 31 from ON to OFF. (ST1-12), and the switching control unit 35 is switched from ON to the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater 10A. An OFF switch request signal is transmitted (ST1-15).

  In FIG. 13, the first induction heater 10 </ b> A takes the initiative, and the first power supply 21, the switching control unit 35, the first power supply output switch 31, and the high frequency connected to the first induction heater. The input switching device 33 and the low frequency input switching device 34 are controlled. However, the sequence control of the induction heating system shown in FIG. 1 may be other than the sequence control shown in FIG. For example, the switching request to ON from the first induction heater 10A to the switching control unit 35 is set as a trigger, and output control information is output to the switching control unit 35 together with the switching request, and the switching control unit 35 is connected to the first power supply 21. The first power output switch 31 and the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater may be controlled. Thus, since the switching control unit 35 controls not only the ON / OFF of each switching unit but also the first power supply 21, the switching control unit 35 may be called a system control unit.

FIG. 14 shows a sequence in which each induction heater 10 induction-heats a workpiece by the induction heating system 1 shown in FIG. 1, and in particular, the first induction heater 10 </ b> A has a first power supply 21 and a second power supply 26. This shows a case where heat treatment is performed by receiving power from the superposition method. In FIG. 14, the second power output switch 32 is controlled instead of the first power output switch 31 in FIG. 13, and ST1-9 and ST1-10 are changed as follows. .
As ST2-9, instead of ST1-9, triggered by the fact that the first induction heater 10A has received the switching completion signal in ST1-8, the first power supply 21 and the second power supply 26 are respectively Send an output start signal.
When receiving the output start signal in ST2-9, the first power supply 21 and the second power supply 26 supply power to the first induction heater 10A based on the output control information received together with the output start signal. The output control information here includes, for example, identification information indicating that only a high frequency is output, output intensity, total output time, and the like as items of output control information notified to the first power supply 21. Items of the output control information notified to the second power source 26 include output intensity, the frequency value when the frequency can be selected, and the total output time.
As ST2-10, instead of ST1-10, when the first power supply 21 and the second power supply finish power supply based on the output control information, a power supply end signal is sent to the first induction heater 10A, respectively. Send.
Thereby, in ST1-11, when the first induction heater 10A receives the power supply end signal from the first power source 21 and the second power source 26, the switching control unit 35 is requested to switch from ON to OFF. Send a signal.

  The sequence shown in FIG. 14 is an example, and various changes can be made as in the case of FIG. In place of ST1-8 and ST2-9 in FIG. 14, the switching control unit 35 includes a second power output switch 32, a high frequency input switch 33 connected to the first induction heater 10A, and a low frequency. When the switching completion signal from OFF to ON is received from the input switching device 34, the switching control unit 35 transmits an output start signal to the first power source 21 and the second power source 26, respectively. When receiving the output start signal, the first power supply 21 and the second power supply 26 supply power to the first induction heater 10A based on the output control information received together with the output start signal. The items of the output control information are the same as described above.

  When the first power supply 21 and the second power supply 26 finish the power supply based on the output control information instead of ST2-10 and ST1-11 in FIG. 14, a power supply end signal is transmitted to the switching control unit 35, respectively. To do. Then, the switching control unit 35 changes from ON to OFF with respect to the second power output switch 32, the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater 10A. Switch request signal is transmitted (ST1-12, ST1-15).

  In FIG. 14, the first induction heater 10 </ b> A takes the initiative, and the first power supply 21, the second power supply 26, the switching control unit 35, the first power supply output switch 31, and the first induction The high frequency input switch 33 and the low frequency input switch 34 connected to the heater are controlled. However, the sequence control of the induction heating system shown in FIG. 1 may be other than the sequence control shown in FIG. For example, the switching request to ON from the first induction heater 10A to the switching control unit 35 is set as a trigger, and output control information is output to the switching control unit 35 together with the switching request, and the switching control unit 35 is connected to the first power supply 21. The second power source 26, the first power source output switch 31, and the high frequency input switch 33 and the low frequency input switch 34 connected to the first induction heater are controlled in sequence. Also good. As described above, the switching control unit 35 not only controls ON / OFF of each switching device but also controls the first power source 21 and the second power source 26, so that the switching control unit 35 is replaced with the system control unit. You may call it.

  With the sequence shown in FIG. 14, even with a single power supply system 20, switching requests from a plurality of induction heaters 10 can be processed without batting.

  As in the sequence control shown in FIGS. 13 and 14, a single power supply system 20, that is, a power supply device, is connected to one of the plurality of induction heaters 10, and power can be supplied from the power supply device. it can. This is because in each induction heater 10 shown in FIG. 1, the heater controller 14 and the switching controller 35 have the following functions.

  That is, the heater control unit 14 has a command to turn on one of the first power output switch 31 and the second power output switch 32 and turn the other off, and a high frequency input switch 33 and This is because the switch control unit 35 is requested to switch the low frequency input switch 34 to either ON or OFF.

  When receiving a command request from each induction heater 10, the switching control unit 35 outputs the first power output switch 31, the second power output switch 32, and the induction heating that outputs the command request according to the command request. The high frequency input switching device 33 and the low frequency input switching device 34 connected to the machine 10 are switched. When the switching control is completed, the switching control unit 35 outputs a switching completion signal to the induction heater 10. Thus, when each induction heater 10 receives a switching completion signal from the switching controller 35, the heater controller 14 controls the outputs of the first power supply 21 and the second power supply 26.

  This shows only one sequence control, and may be changed as follows, for example. That is, when receiving a command request from each induction heater 10, the switching control unit 35 outputs the first power output switch 31 and the second power output switch 32 and the command request according to the command request. The high-frequency input switch 33 and the low-frequency input switch 34 connected to the induction heater 10 are switched. After that, when the switching control is completed, the switching control unit 35 either or both of the first power supply 21 and the second power supply 26 according to the output control information received together with the above-described command request from each induction heater 10. Control the output.

Thus, according to the induction heating system 1 shown in FIG. 1, various heat treatments can be performed by the following four types of switching modes.
As the first switching mode, one frequency, that is, high-frequency power supply is received from the first power supply 21.
As the second switching mode, power is supplied from the second power source 26.
As the third switching mode, power of different frequencies is received from the first power supply 21 in a time division manner.
As a fourth switching mode, power having one frequency from the first power supply 21 and power from the second power supply 26 are received and supplied by superimposing both powers.
Therefore, according to the induction heating system 1 shown in FIG. 1, the heat processing which has a frequency effect can be performed.

  Although the method for sequentially heating a plurality of workpieces by the induction heating system 1 has been described, the induction heating system 1 shown in FIG. 1 simultaneously supplies power to two or more induction heaters 10 that are electrically symmetrical from the power supply system 20. It is also possible to do. In that case, in the switching control part 35, it is necessary to turn ON the high frequency input switch 33 and the low frequency input switch 34 which are connected to the induction heater 10 which supplies power simultaneously. Other than that, it may be changed as appropriate according to the sequence shown in FIGS.

  Moreover, the induction heating system 1 can be used in accordance with the heat treatment of the workpiece, such as quenching with one induction heater 10 and tempering with another induction heater 10.

[Supply to multiple induction heaters with one power supply system]
FIG. 15 is a time chart showing how many induction heaters can be supplied using one power supply system. FIG. 15A shows a case where two induction heaters are used. ) Shows a case where three induction heaters are used, and (c) shows a case where five induction heaters are used. Let cycle time be τ. In this time chart, it is assumed that the same heat treatment is performed by a plurality of induction heaters 10 using one power supply system 20. This time chart is applied to both the superposition method and the time division method.

  In FIG. 15, “switching processing” refers to high-frequency input switching of the first power output switch 31, the second power output switch 32, and each induction heater 10 in the induction heating system 1 shown in FIG. 1. This means switching ON / OFF of the device 33 and the low frequency input switch 34.

  In FIG. 15, “heating treatment” means a power supply system for any induction heater 10 in the induction heating system 1 shown in FIG. 1, that is, one of the first power supply 21 and the second power supply 26, or It means that electric power is supplied from one side to one induction heater 10 and the workpiece is heated by the heating coil 13 in the induction heater 10.

  In FIG. 15, “cooling treatment” refers to cooling the work by injecting a quenching liquid or a cooling liquid onto the work in the induction heating system 1 shown in FIG. 1.

  In FIG. 15, “attachment / detachment process” means that the work subjected to the induction heating process is removed from the work supporting means (not shown) in the induction heating system 1 shown in FIG. 1 and placed on the next work.

  In each induction heater 10, the switching process, the heating process, the cooling process, and the attaching / detaching process are repeated in this order. The switching time, heating time, cooling time, and attachment / detachment time are Ta, Tb, Tc, and Td, respectively. When n induction heaters 10 are used, the heating time and the cooling time are expressed as Tbn and Tcn. Note that the switching time Ta and the attachment / detachment time Td are values independent of the number of units. The cycle time τ and each time Ta, Tb, Tc, Td have a relationship of τ = Ta + Tb + Tc + Td.

  In the induction heating system 1, when two induction heaters 10 are used, as shown in FIG. 15A, the switching process of the first induction heater 10A is performed, and then the heating process is performed. When the heating process is completed, the switching process is started. The cooling process is immediately started in the first induction heater 10A, while the second induction heater 10B performs the heating process after the switching process is completed. When the cooling time Tc2 elapses in the first induction heater 10A, the attachment / detachment process is performed, but in the second induction heater 10B, the heating process is continued. When the heating time Ta2 elapses in the second induction heater 10B, the switching process is started. The cooling process is immediately started in the second induction heater 10A, while the switching process is completed in the first induction heater 10A. Wait for heat treatment. Thereafter, the first induction heater 10A repeats the same process in order, and the second induction heater 10B performs the attachment / detachment process when the cooling time Tcn elapses, and repeats the same process in the following order.

  Here, when the number of induction heaters 10 operated in the induction heating system 1 is three with the same cycle time τ, it is difficult to shorten the switching time Ta and the attachment / detachment time Td. As shown, the heating time Tb and the cooling time Tc are made different from the case of two induction heaters 10.

  Therefore, assuming that n units (n is an arbitrary integer of 2 or more) are operated in the induction heating system 1 with the same cycle time τ, as shown in FIG. 15C, each of the heating time Tbn and the cooling time Tcn. Time is obtained, and the induction heating condition and the cooling condition according to the cooling time Tcn are set according to the obtained heat treatment time Tbn.

  As described above, when a plurality of induction heaters 10 are operated with a cycle time τ using a single power supply system, a period in which the power supply system 20 is connected to each induction heater 10 and power can be supplied, that is, a heating time is obtained. In each induction heater 10, conditions such as DT ratio, selection of frequency, and power of each frequency may be set so as to satisfy predetermined heating conditions corresponding to the obtained heating time.

[Setting of control from induction heater]
In the induction heating system 1 shown in FIG. 1, a method for setting the heating conditions from each induction heater 10 to the system control unit including the switching control unit 35 will be described.

  FIG. 16 shows an example of a condition setting screen used when setting the heating conditions from each induction heater to the system control unit including the switching control unit, where (a) is an example of step condition setting; (b) is a setting table of time division method 1, (c) is a setting table of time division method 2, and (d) is a diagram showing a table of superposition method 1.

  In the table shown in FIG. 16A, each vertical item indicates the order of steps, and each horizontal item has STEP as the step number, TIMER as the time, Rotate as the number of rotations of the workpiece, and HSWTTABLE. Is the table reference destination information of the time division method, HSW2VR is the output intensity, HSW2DT is the output ratio between the high frequency and the low frequency, 2BADTABLE is the table reference destination information of the superposition method, and 2BNDVR is the second power supply 26. 2BNDFREQ is information on the frequency of the second power supply 26.

As shown in FIG. 16A, time is set in the TIMER item and the work rotation speed is set in the ROTATE item for each step.
In the case of adopting the time division method, the information of the setting table destination to be referred is set when the table heating is performed, and when the step heating is performed, the output intensity VR and the low frequency as shown in FIG. Each of the occupation ratios DT is set.
In the case of adopting the superposition method, the setting table destination information to be referred to is set when performing table heating, and the output intensity VR and the frequency are set when performing step heating. Here, setting the frequency means setting which frequency is output on the assumption that the frequency output from the second power supply 26 can be set.

Here, the step heating means that the heating condition and the heating signal whose items are the output intensity VR and the low frequency occupation ratio DT are transmitted from the induction heater to the power supply system 20 via the switching control unit 35 for each step. In this method, the power sources of the first power source 21 and the second power source 26 receive the heating condition and the heating signal to control the output to heat the workpiece.
On the other hand, with table heating, a table as shown in FIGS. 16B to 16D is transmitted in advance from the induction heater to the power supply system 20 via the switching control unit 35, and the first power supply 21 is supplied. In this method, each power source of the second power source 26 controls the output along the table to heat the workpiece.

  When step heating is employed, a signal is transmitted from the induction heater to the power source for each step to control the start and end of heating, so that an error occurs in the heating time due to transmission and reception of signals. On the other hand, when table heating is employed, since the heating start signal and the end signal are not transmitted / received from the induction heater every heating, the heating time can be accurately controlled. In the table heating, even when the heating conditions are changed in time series in one table, the heating time under each heating condition can be accurately controlled. In other words, by adopting table heating, the heating conditions are raised in advance by sending the heating conditions to the power supply in advance, and even when the heating conditions change, it is possible to output accurately with the heating time of each heating condition. Is possible.

  In each step of FIG. 16A, the item “HSWTABLE” “0” means that the first power source 21 does not perform table heating, and the item “2BANDTABLE” “0” means that the first power source 21 This means that the second power source 26 does not perform table heating. On the other hand, when the item of HSWTTABLE is “1”, it means that the first table of the time division method shown in FIG. 16B is referred to, and when the item of HSWTTABLE is “2”, it is shown in FIG. This means that the second table of the time division method is referred to, and if the item of 2BANDTABLE is “1”, it means that the first table of the superposition method shown in FIG.

  16 (b) and 16 (c), VR, DT, and HT respectively indicate output intensity, low frequency occupancy, and heating time. In FIG. 16 (d), VR, FRQ, and HT respectively indicate output intensity, Indicates the output frequency and heating time.

  In this way, the heating condition from each induction heater 10 to the system control unit including the switching control unit 35 is set.

[Settings for output monitoring]
A description will be given of how output monitoring is performed when conditions are set as in each table shown in FIG. FIG. 17 is a diagram illustrating an example of an output monitoring screen.

  In FIG. 16, power supply is performed in STEP3, STEP5, and STEP7. Therefore, as the output monitoring step, the numbers “3”, “5”, and “7” of STEP3, STEP5, and STEP7 are shown. In each of STEP3, STEP5, and STEP7, the table monitoring row is, for example, in STEP3, since HSWTABLE is “1” from the table of FIG. 16A, refer to FIG. Set whether to perform. “Monitoring mask time” means a time during which heating is not monitored after the start of heating, and “existence monitoring only” is “present” means that monitoring is performed with a value at the end of heating. In FIG. 17, the time division method and the superposition method are set, respectively, and the power P1, P2, and the direct current Idc and the direct current voltage Vdc input from the conversion units 21a, 26a to the reverse conversion units 21b, 26b in FIGS. , Frequencies F1 and F2 are set. For any parameter, an upper limit and a lower limit are set, and the measured value is displayed.

  By the way, each power supply control part 21x, 26x of the 1st power supply 21 and the 2nd power supply 26 is controlled so that direct current voltage may become constant, or is controlled so that direct current may become constant. Therefore, the output status from each power supply monitors its control object. That is, the DC voltage Vdc is monitored if each of the power supply control units 21x and 26x is DC voltage constant control, and the DC current Idc is monitored if the DC current constant control is performed.

  Therefore, in the time division method, either Vdc or Idc, which is a control target, and the frequency are continuously monitored, and the power is monitored at the value at the end of heating. On the other hand, in the superposition method, either Vdc or Idc, which is a control target, and the frequency are continuously monitored, and the power is monitored at the value at the end of heating. In FIG. 17, when “only end monitoring” is “present”, all values at the end of heating are monitored.

Next, a monitoring method will be described.
When table heating is adopted, there are the following monitoring methods.
As a first procedure, each value is set on a monitoring screen as shown in FIG.
As a second procedure, it is set which table heating at which step of condition setting is to be monitored and which of the 15 rows of the monitored table is to be monitored. FIG. 17 shows a case where three rows can be set as the table heating row to be monitored.
As a third procedure, the inverter table operation measurement data device is always read and the corresponding table row is monitored. Here, the inverter table operation measurement data device is a measurement unit described later. As will be described later, since the power is monitored by average power, the value at the end of heating is read and monitored.

  When step heating is adopted, that is, even when step output intensity VR, low frequency occupancy DT, and frequency are input, each value is set on the monitoring screen, and step heating of any step of condition setting is performed. Is monitored, the inverter table operation measurement data device is always read, and the DC voltage Vdc, DC current Idc, power at the end of heating, and frequency at the steps set as monitoring targets may be monitored.

[Equipment for monitoring power]
How to monitor power from the circuits shown in FIGS. 3 and 4 will be described in detail. As shown in FIGS. 3 and 4, the inverter control units 21c and 26c control the conversion units 21a and 26a and the inverse conversion units 21b and 26b. Therefore, the direct current Idc and voltage Vdc flowing from the conversion units 21a and 26a to the inverse conversion units 21b and 26b are measured by the current sensor 101 and the voltage sensor 102 shown in FIGS. 3 and 4 and input to the measurement unit 103. The value input to the measurement unit 103 is digitally converted and output to the processing unit 104. The measurement unit 103 is provided in each of the first power source 21 and the second power source 26, and the processing unit 104 is provided in each induction heater 10 or a management unit (not shown) that controls the induction heating system 1. .

  There are various monitoring methods for the electric power during operation of the induction heating system 1. Hereinafter, a case where power is supplied by a time division method using a DT signal will be described.

FIG. 18 is a diagram for explaining the first output monitoring method, where the horizontal axis represents time and the vertical axis represents Vdc, Idc, and DT. As a first output monitoring method, when the DT signal is ON, that is, when a low-frequency output is being made, the instantaneous values v _dc and i _dc are detected by the current sensor 101 and the voltage sensor 102. . Thereby, low frequency and high frequency electric power can be obtained from the following equation.
The low frequency power P1 (kW) is
P1 = v _dc (V) × i _dc (A) × DT (%) × 10 ⁻² × 10 ⁻³
The high frequency power P2 (kW) is
P2 = v _dc (V) × i _dc (A) × (100−DT (%)) × 10 ⁻² × 10 ⁻³

In this first output monitoring method, _vdc is relatively stable, but Idc changes with time in DT. This is because in the time-sharing method, for example, the DC voltage is output so as to be constant by the power supply control method, so that the current changes due to a change in load impedance. For this reason, the monitoring is not accurate.

Therefore, as a second monitoring method, in the present invention, the instantaneous values v _dc and i _dc are detected by the current sensor 101 and the voltage sensor 102 at predetermined intervals Δt (for example, 0.5 ms), and v _dc × i _dc That is, the product of the instantaneous value of each DC voltage and DC current is obtained every sampling time, and during each step heating period, the low frequency and the high frequency are added separately to obtain the power at the end of the step.

  FIG. 19 is a diagram for explaining a second output monitoring method, where (a) shows time variations of DC voltage and current, and (b) to (e) are DT signal and low-frequency integrated power consumption, respectively. , The high-frequency integrated electric energy and the time change of the heating signal are shown.

As shown in FIG. 19A, since the DC voltage and current change with time, instantaneous values are detected by the current sensor 101 and the voltage sensor 102 every sampling time, for example, 0.5 ms. Then, the power time product q (J) is obtained by the following equation for each sampling time.
q (J) = v _dc (V) × i _dc (A) × sampling time (s)

Next, a sum QL (J) of low-frequency time products and a sum QH (J) of high-frequency time products are respectively obtained by the following equations.
QL (J) = Σq (J) (However, addition is performed while DT is High (low frequency output).)
QH (J) = Σq (J) (However, addition is performed while DT is Low (high frequency output).)

Then, the low frequency average power P1 (kJ / s) and the high frequency average power P2 (kJ / s) are obtained by the following equations. However, HT (s) is the total heating time.
P1 (kJ / s = kW) = QL (J) / HT (s) × 10 ⁻³
P2 (kJ / s = kW) = QH (J) / HT (s) × 10 ⁻³

  In the induction heating system 1 according to the embodiment of the present invention, the output monitoring device 110 is wired to the first power supply 21 and the second power supply 26 in the power supply device 20 as the power supply system shown in FIGS. 3 and 4. Connected and attached. FIG. 20 is a block configuration diagram of the output monitoring apparatus 110. The output monitoring apparatus 110 includes a measurement unit 103 and a processing unit 104.

The measurement unit 103 measures the direct current Idc and the voltage Vdc output from the conversion units 21a and 26a shown in FIGS. 3 and 4 to the inverse conversion units 21b and 26b with the sampling time.
The processing unit 104 obtains the amount of power for each frequency from the current and voltage values measured by the measuring unit 103 for each sampling time, and obtains the average power of each frequency based on the amount of power for each frequency.

  The power supply device 120 is attached to the plurality of induction heaters 10 via the switching means 30, and the power supply device 120 controls the switching means 30 from the plurality of induction heaters 10, so that the power supply device 120 can be connected to any one induction unit. It is configured to be connectable to the heater 10. In such a configuration, the processing unit 104 is provided in each of the plurality of induction heaters 10. Thereby, the measurement data by the measurement part 103 can be acquired with respect to the electric power supply apparatus 120, and each process part 104 is consistency with the supply command which performed the average electric power of each frequency with respect to the electric power supply apparatus 120. Judging.

  As illustrated in FIG. 20, the measurement unit 103 includes a current voltage measurement unit 103 a and a frequency measurement unit 103 b so as to correspond to a method in which the power supply device 120 supplies power in a time division manner. That is, the current / voltage measuring unit 103a generates a direct current output from the conversion units 21a and 26a to the inverse conversion units 21b and 26b from the detection values input from the current sensor 101 and the voltage sensor 102 shown in FIGS. And measure the voltage at the sampling time. The frequency measuring unit 103b measures the frequency of the output current and voltage by counting the number of times per unit time that the inverse conversion units 21b and 26b are turned on / off.

  Therefore, the processing unit 104 obtains the electric power for each frequency obtained by the frequency measuring unit 103b from the values of the current and the voltage measured by the current / voltage measuring unit 103a for each sampling time, and determines each electric power based on the electric energy for each frequency. Find the average power of the frequency.

[Output monitoring method]
A method of monitoring output using the output monitoring apparatus 110 shown in FIG. 20 will be described.
As shown in FIG. 3, when the DC is turned on / off at the first frequency (for example, low frequency) and the second frequency (for example, high frequency) by the inverse conversion unit 21b and output, first, the current / voltage measurement unit 103a. However, the DC current and voltage are measured with the sampling time from the detection data input from the current sensor 101 and the voltage sensor 102.

  Next, when the inverse conversion unit 21b is turned on / off at the first frequency, the processing unit 104 receives input of the current and voltage sampled and measured by the current / voltage measurement unit 103a. The processing unit 104 obtains the average output power of the first frequency by adding the input value, that is, the product of the current and voltage for each sampling time and dividing the sum by the induction heating time that is the output time. Further, when the inverse conversion unit 21b is turned on / off at the second frequency, the processing unit 104 receives input of current and voltage sampled and measured by the current / voltage measurement unit 103a. The processing unit 104b integrates the input values, that is, current and voltage values, adds the integrated result values every sampling time, and divides by the induction heating time that is the output time, thereby obtaining the second frequency. The average output power is obtained.

  Then, the processing unit 104 displays the supplied power on the display unit (not shown) from the obtained average output power of the first frequency and the average output power of the second frequency, and so on. To monitor. It is monitored whether the average output powers of the first frequency and the second frequency are within the upper limit value and the lower limit value set by the processing unit 104. Is output and output is stopped. Thus, when a threshold value is set and the threshold value is deviated, or when an allowable range is set and deviated from the range, the output is stopped, and a workpiece that is not properly subjected to induction heating processing can be removed. .

  In this way, the output monitoring device 110 samples Vdc and Idc for the entire heating time at regular intervals and obtains the average power for each frequency, so that it can be monitored including changes such as rising of the output. it can. That is, by shortening the heating time, it is possible to monitor the transient state of the output rise.

  In the output monitoring method according to the embodiment of the present invention, the low-frequency integrated power amount is divided by the total heating time to obtain the average power, and the high-frequency integrated power amount is divided by the total heating time to obtain the average power.

  For this reason, in the processing unit 104, the DT signal that specifies switching between the first frequency and the second frequency is changed according to the change in the magnitudes of the obtained average power of the first frequency and the average power of the second frequency. Anomalies can be monitored.

  If an abnormality occurs in the DT signal and the output times of the first frequency and the second frequency change, the integrated electric energy in the output period of the first frequency and the integration of the output period of the second frequency The amount of power changes. As a result, the average power of each frequency divided by the total output time also changes. Therefore, switching between the first frequency and the second frequency can be specified by monitoring whether the average power value of the first frequency and the average power value of the second frequency change over time. The so-called DT signal abnormality can be monitored. Thus, by monitoring the average power of each frequency, the DT signal can also be monitored.

  Next, superimposition output monitoring will be described. In the system shown in FIG. 1, the average power may be obtained by accumulating DC voltage and current in the first power source 21 and the second power source 26 and dividing the sum by the total heating time. After that, output can be monitored in the same way as the time division method.

[Modification of output monitoring method]
The above-described output monitoring method is a method in the case where power is supplied by the time division method, but this monitoring method can also be applied to the case of alternately outputting a low frequency and a high frequency in a short time in the superposition method. Can do. Details will be described below. FIG. 21 is a diagram showing, in a time series, the presence / absence of the output of the first frequency and the presence / absence of the output of the second frequency when power is supplied by the superposition method.

  In the circuit configuration of the superposition method shown in FIG. 4, as shown in FIG. 21, a signal that is output by turning ON / OFF the direct current at the first frequency in the inverse conversion units 21b and 26b, and the direct current is turned on at the second frequency. Assume a case where signals are output alternately after being turned off.

  First, each measurement unit 103 shown in FIG. 4 receives detection signals from the current sensor 101 and the voltage sensor 102, and measures each DC current and voltage with a sampling time.

  Next, when the inverse conversion unit 21b is turned on / off at the first frequency, the processing unit 104 receives input of the current and voltage sampled and measured by the current / voltage measurement unit 103a. The processing unit 104 calculates the average output power of the first frequency by integrating the input values, that is, current and voltage values, adding the integrated result values every sampling time, and dividing the result by the output time. . In addition, when the inverse conversion unit 26b is turned ON / OFF at the second frequency, the processing unit 104 receives an input of current and voltage sampled and measured by the current / voltage measurement unit 103a. Then, the processing unit 104b integrates the input values, that is, current and voltage values, adds the integrated result values every sampling time, and divides by the output time, thereby obtaining the average output power of the second frequency. Ask for.

  Then, the processing unit 104 displays the supplied power on a display unit (not shown) based on the calculated average output power of the first frequency and the average output power of the second frequency. Have supervisors monitor.

  As described above, in the embodiment of the present invention, in the first power supply 21 and the second power supply 26 constituting the power supply 20, the direct current voltage and the direct current output from the conversion units 21a and 26a to the reverse conversion units 21b and 26b. The current is measured by the measuring unit 103 at every sampling time. Therefore, the power output from the first power supply 21 and the second power supply 26 can be monitored.

[Monitoring power supply to a single induction heater]
So far, the description has mainly focused on the case where one of the plurality of induction heaters 10 is connected to the power supply system 20 via the switching means 30 and power is supplied from the power supply system 20 to the induction heater 10. . However, the same applies to the case where power is supplied to one induction heater 10.

  That is, if it is set as the induction heating system 1 provided only with the induction heater 10A among FIG. 1, it will become as follows. The induction heating system 1 has only the first power source 21 or both the first power source 21 and the second power source 26 as one or a plurality of power supply devices 120. As shown in FIGS. 3 and 4, the first power supply 21 includes a conversion unit 21 a that converts alternating current into direct current, and an inverse conversion unit that outputs the direct current input from the conversion unit 21 a by turning it on / off at an arbitrary frequency. 21b. As shown in FIG. 4, the second power supply 26 includes a conversion unit 26 a that converts alternating current into direct current, an inverse conversion unit 21 b that outputs the direct current input from the conversion unit 26 a by turning it on / off at an arbitrary frequency, have. As shown in FIGS. 3 and 4, the power supply device 120 is connected to supply power to the single heating coil 13. Here, the single heating coil 13 may be a plurality of coil portions connected in series or in parallel when there are a plurality of heating regions in one work, and the plurality of coils in this case It is for calling together. One heating coil corresponds to one workpiece, and the one heating coil is referred to as a single heating coil.

  In such an induction heating system 1, an output monitoring device 110 having a measurement unit 103 and a processing unit 104 shown in FIG. 20 is provided. The measurement unit 110 measures the DC voltage and current output from the conversion units 21a and 26a to the inverse conversion units 21b and 26b at each sampling time. As described with reference to FIG. 20, the measurement unit 103 includes a current-voltage measurement unit 103a and a frequency measurement unit 103b. On the other hand, the processing unit 104 obtains the amount of power for each frequency from the current and voltage values measured by the measuring unit 103 for each sampling time, and obtains the average power of each frequency based on the amount of power for each frequency.

  When such induction heating system 1 is used to perform induction heating by switching on or off one or more direct currents at one or more frequencies, each of first power source 21 and second power source 26 The current and voltage output from the converters 21a and 26a to the inverse converters 21b and 26b are measured at each sampling time, and the product of the current and voltage measured at the sampling time is added for each frequency to obtain the average power for each frequency. Ask. As a result, the output status of the power supply device 120 can be monitored from the obtained average power for each frequency.

  In the case where the power supply device 120 supplies in a time division manner, the operation is as follows. As the power supply device 120, as shown in FIG. When the inverse conversion unit 21b of the first power supply 21 adjusts the output power of the high frequency and the low frequency as the ratio of the output time of the high frequency and the low frequency with respect to the output period, specifically, When the inverse conversion unit 21b alternately outputs a low frequency and a high frequency, the processing unit 103 causes the measurement unit 103 to perform a direct current for each sampling time based on values input from the current sensor 101 and the voltage sensor 102. The average power of the high frequency and the low frequency supplied to the heating coil 13 from the first power supply 21 as one power supply device 120 is obtained by calculating the product of the DC voltage and the DC voltage.

  That is, the high frequency as the first frequency and the low frequency as the second frequency, one direct current is distinguished by the DT signal and turned on / off, and the high frequency and the low frequency are output by time division multiplexing to perform induction heating. In doing so, one DC current and voltage is measured every sampling time. The product of the current and voltage measured when turning ON / OFF at the first frequency is added every sampling time to obtain the average power at the first frequency. Similarly, the average power of the second frequency is obtained by adding the product of the current and voltage measured when turned on / off at the second frequency for each sampling time. The output power can be monitored from the obtained average powers of the first frequency and the second frequency.

  In the case where the power supply device 120 supplies in the superposition method, the operation is as follows. As shown in FIG. 4, the power supply device 120 includes a first power supply 21 as a first power supply device and a second power supply 26 as a second power supply device. In this case, in the first power supply 21, the inverse conversion unit 21b turns on and off the direct current input from the conversion unit 21a at the first frequency and outputs the direct current. At the same time, in the second power source 26, the inverse conversion unit 26b turns on and off the direct current input from the conversion unit 21a at the second frequency and outputs it. Power is supplied to the heating coil 13 by superimposing the first frequency and the second frequency from the two power sources of the first power source 21 and the second power source 26.

  In this case, as shown in FIG. 4, the measurement unit 103 includes a first measurement unit 103 c provided in the first power supply 21 and a second measurement unit 103 d provided in the second power supply 26. The first measurement unit 103c measures the direct current and voltage output from the conversion unit 21a to the inverse conversion unit 21b in the first power supply 21 at each sampling time. The second measurement unit 103d measures the direct current and voltage output from the conversion unit 26a to the inverse conversion unit 26b in the second power supply 26 at each sampling time.

  Therefore, the processing unit 104 obtains the electric energy of the first frequency from the current and voltage sampling time values measured by the first measuring unit 103c, and samples the current and voltage measured by the second measuring unit 103d. The power amount of the second frequency is obtained from the value for each time, and the average power of the first frequency and the average power of the second frequency are obtained based on the power amount for each frequency.

  That is, the first direct current 21 is turned on / off at the first frequency and output from the first power supply 21, and the second direct current is turned on / off from the second power supply 26 at the second frequency. When the induction heating is performed by superimposing the first frequency and the second frequency, the first measurement unit 103c measures the first direct current and the voltage every sampling time and performs the second measurement. The unit 103d measures the second direct current and voltage at each sampling time. Then, the product of the first direct current and voltage measured when the processing unit 104 is turned ON / OFF at the first frequency is added every sampling time, and divided by the induction heating time, thereby obtaining the first Find the average power of the frequency. Similarly, the product of the second direct current and voltage measured when the processing unit 104 is turned on / off at the second frequency is added every sampling time, and divided by the induction heating time to obtain the second The average power of the frequency is obtained. The processing unit 104 monitors the output power from the obtained average power of the first frequency and the obtained second average power value.

  In addition, as shown in FIG. 1, since the induction heating system 1 has already been described in the case where a plurality of induction heaters are provided, it will not be necessary to repeat the description here.

  As described above, the power supply is monitored by the output monitoring device 110 in the induction heating system 1. Thereby, it is possible to monitor a load abnormality, a bus bar abnormality, and the like.

[Other monitoring]
Since the output monitoring device 110 is provided in the induction heating system 1 shown in FIG. 1, the power supplied to each induction heater 10 can be monitored. By using this output monitoring device 110, it is possible to monitor the frequency actually output and the Vdc at the time of heating for a very short time.

  For example, in the output monitoring apparatus 110, the DC voltage Vdc input to the inverse conversion units 21b and 26b can be measured and monitored constantly by the current / voltage measurement unit 103a for each sampling time. In that case, ignoring for several milliseconds immediately after the switching of the frequency, for example, the period from the value obtained by averaging a plurality of data of 4 to 6 ms to the end of the frequency is integrated for each sampling time, By dividing, the average DC voltage can be monitored.

  For example, in the output monitoring apparatus 110, the frequency can be measured by monitoring the number of times per unit time of switching by the inverse conversion units 21b and 26b shown in FIGS. 3 and 4 by the frequency measurement unit 103b. Therefore, the output frequency can be constantly monitored while the power of each frequency is output.

  For example, Vdc and frequency can be measured and monitored even in very short heating.

  In this way, even during power supply, the DC voltage and frequency to be controlled can be constantly monitored, and a guideline can be given that indicates whether induction heating is being performed appropriately.

  Although the embodiments of the present invention have been described above, the scope of the present invention includes those modified within the scope of the invention described in the claims.

1: induction heating system 2: commercial power supply 10, 10A, 10B, 10C: induction heater 11: current transformer for high frequency 11a: primary winding 11b: secondary winding 11c: capacitors 11d, 11e: coils 12, 12A, 12B: Current transformer for low frequency 12a: Primary winding 12b: Secondary winding 12c: Tap 12d: Core 12e, 12f: Reactance 13: Heating coil 14: Heater controller 20: Power supply system (power supply device)
21: 1st power supply 21a: Conversion part 21b: Inverse conversion part 21c: Inverter control part 21d: High pass filter 21e: Low pass filter 21x: Power supply control part 26: 2nd power supply 26a: Conversion part 26b: Inverse conversion part 26c: Inverter control unit 26x: power supply control unit 30: switching means 31: first power output switch 32: second power output switch 33: high frequency input switch 34: low frequency input switch 35: switching Control unit 51: Duct frame 51a: Vertical frame 51b: Horizontal frame 51c: Depth frame 52: High-frequency power supply path 53: Low-frequency power supply path 52a, 52b, 53a, 53b: Busbar (high-frequency power transmission busbar, low-frequency power transmission Busbar)
52c, 52d, 53c, 53d: Mounting hook 54: Insulator 55: Slot 60: Switch 61a, 62a: Upstream bus bar mounting portion 61b, 62b: Downstream bus bar mounting portion 63: Base plate 64a: Cooling water inlet 64b : Cooling water discharge ports 63a, 63b, 63c: Slot 65: Connection block 65a: Contact portion 65b: Support portion 65c: Rod 66: Support block 67: Air cylinder 68: Compression spring 69: Cooling pipe 70: Solenoid valve 71 : Limit switch 72: insulator 80: pedestal 80a: side edge guide portion 80b: carriage stopper 80c: mounting support portion 81, 83: primary bus bar 82: secondary bus bar 84: quenching liquid injection nozzle 86, 87: connection Part 88: Upper support part 89: Lower support part 90: Exchange mechanism 91: Cover member 91a: Connection opening 91b: Packing 92: Front / rear direction support Holding part 93: Base plate 93a: Running surface 93b: Base projecting part 93c: Base rib 93d: Extension plate 94: Carriage 94a: Handle 94b: Carriage plate 94c: Carriage rib 94d: Cam follower 94e: Fixing member 95: Forward displacement means 95a: fixing block 95b: push screw part 95c: screwing member 96: inclined member 97: vertical displacement means 98: roller 99: jig 99a: guide surface 99b: jig fixing screw 101: current sensor 102: voltage sensor 103: Measurement unit 103c: first measurement unit 103d: second measurement unit 103a: current voltage measurement unit 103b: frequency measurement unit 104: processing unit 110: output monitoring device P1: connection position P2: exchange position

Claims (3)

Each induction heater formed by connecting each secondary side of the high frequency current transformer and the low frequency current transformer to the heating coil in parallel;
Of the above induction heaters, a high frequency input switch connected to the primary side of the high frequency current transformer,
Of the above induction heaters, a low frequency input switch connected to the primary side of the low frequency current transformer,
A first power source that adjusts a ratio of a high frequency and a low frequency output time to an output cycle to output high frequency and low frequency power;
A second power source that outputs power having a frequency different from the frequency of power output from the first power source;
A first power output switch connected to a low frequency output terminal among the output terminals of the first power supply;
A second power supply output switch connected to the output terminal of the second power supply;
By controlling the high-frequency input switch and the low-frequency input switch for each induction heater, and controlling the first power output switch and the second power output switch, A switching control unit for connecting at least one of the induction heaters and one or both of the first power source and the second power source;
With
Each induction heater includes a command to turn on one of the first power output switch and the second power output switch and turn the other off, and the high frequency input switch and the low power switch. An induction heating system having a heater control unit that requests the switching control unit to switch the frequency input switching unit to either ON or OFF. When the switching control unit receives a command from each induction heater, the first power supply output switcher, the second power supply output switcher, and the induction heater that outputs the command in accordance with the command Control the high-frequency input switch and low-frequency input switch connected to the
When the switching control unit finishes the control corresponding to the command from each induction heater, it outputs a switching completion signal to the induction heater,
2. The induction heating system according to claim 1, wherein each induction heater controls an output of the first power source and the second power source when receiving a switching completion signal from the switching control unit. A plurality of induction heaters having heating coils, a first power source that outputs high-frequency and low-frequency power by adjusting a ratio of high-frequency and low-frequency output times with respect to the output cycle, and output from the first power source Using a second power source that outputs power of a frequency different from the frequency of the power to be generated, and switching means,
A first switching mode in which power having one frequency is supplied from the first power source, a second switching mode in which power is supplied from the second power source, and different frequencies in time division from the first power source The third switching mode for receiving the power supply of the fourth, the fourth switching for receiving the power having one frequency from the first power source and the power from the second power source and superimposing both powers and receiving the power An induction heating method in which the switching means is switched from an arbitrary induction heater among the plurality of induction heaters so as to be in any of the modes, and the work placed in the arbitrary induction heater is induction heated.

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