JP5927606B2 - Method for detecting misalignment between heating coil and workpiece - Google Patents

Description

  The present invention relates to a method for detecting misalignment between a heating coil and a workpiece when performing induction heating.

  Various heat treatments are performed to improve physical properties such as the hardness of the workpiece. Among heat treatments, an induction heating method is known as a method that can heat a workpiece to a predetermined temperature in a short time. The present applicant has developed an apparatus for determining whether induction heating is appropriately performed (for example, Patent Document 1).

  FIG. 9 is a block diagram illustrating an outline of an apparatus disclosed in Patent Document 1 (hereinafter simply referred to as “monitoring apparatus”). As shown in FIG. 9, the monitoring device 20 is attached to the high-frequency heating device 10, and the high-frequency heating device 10 is electrically connected to a high-frequency inverter 11 as a power source and an output terminal of the high-frequency inverter 11. It comprises a matching capacitor 12 connected in between, a heating coil 14 for inductively heating the workpiece 15, and a current transformer 13 interposed between the matching capacitor 12 and the heating coil 14. . Therefore, the high-frequency heating device 10 is configured such that the matching capacitor 12 and the heating coil 14 include a parallel resonance circuit in an equivalent circuit. The current transformer 13 includes a primary coil 13 a connected in parallel to the matching capacitor 12 to the high-frequency inverter 11 and a secondary coil 13 b connected in parallel to the heating coil 14.

  The monitoring device 20 includes a current sensor 21 that detects an output current of the high-frequency inverter 11 as a power source, a voltage sensor 22 that detects a voltage in the heating coil 14, a detection signal of the current sensor 21, and a detection signal of the voltage sensor 22. And a control unit 23 that performs quenching management based on the control unit 23.

  The control unit 23 includes a current detection unit 23a that receives a detection signal input from the current sensor 21, a voltage detection unit 23b that receives a detection signal input from the voltage sensor 22, and a current detection unit 23a and a voltage detection unit 23b. A signal processing unit 23c that receives the input and performs signal processing, and a determination unit 23d that receives the input of the result of signal processing by the signal processing unit 23c and determines whether the result is within a predetermined range. Yes. The determination unit 23d includes a display unit 23e that outputs the result of the signal processing performed by the signal processing unit 23c.

The signal processing unit 23c includes a current I _o which is input from the high-frequency inverter 11 capacitor 12, the circuit composed of the current transformer 13 and the heating coil 14, both ends 22a of the heating coil 14, the coil voltage V _Ciol between 22b In addition to the signal processing related to the above, signal processing for _{obtaining the} impedance is also performed using the current I _o and the coil voltage V _ciol .

When the heating coil 14 and the work 15 are at the reference position, any one or more of the current I _O , the voltage V _coil generated in the heating coil 14, and the impedance are measured and used as reference data, and the induction heating process to be monitored is performed. When performing, one or more of the current I _O , the voltage V _coil generated in the heating coil 14, and the impedance are measured to determine whether or not the determination unit 23 d is within the reference data. When the warning unit 24 receives a warning signal from the determination unit 23d, the warning unit 24 displays a warning, generates a warning sound to the outside, and supplies high-frequency power to a control unit (not shown) of the high-frequency inverter 11. Instructing the output to stop.

WO2009 / 035011A1

  The apparatus disclosed in Patent Document 1 is suitable for determining whether or not the gap between the workpiece 15 and the heating coil 14 is in an appropriate state. However, even when the work 15 and the heating coil 14 have an appropriate gap, when the facing surfaces of the work 15 and the heating coil 14 are slid and moved, a so-called lateral shift is caused. Therefore, appropriate monitoring is difficult with the monitoring device 20 disclosed in Patent Document 1. For example, assuming that the workpiece is cylindrical and the inner peripheral surface is heated in a ring shape, the heating coil is arranged in the cylinder of the workpiece, and the radial distance between the ring-shaped heating region and the heating coil is appropriate. Even in the situation where the vertical positional relationship between the ring-shaped heating region and the heating coil is not appropriate, whether or not induction heating is appropriately performed even if the monitoring device disclosed in Patent Document 1 is used. Judgment is difficult.

  Therefore, in the present invention, by monitoring the voltage generated in the heating coil and the current output from the inverter, it is possible to determine whether or not the positional relationship between the heating coil and the work is appropriate. It is an object of the present invention to provide a method for detecting a positional deviation between a workpiece and a workpiece.

In order to achieve the above object, the following measures are taken.
[1] In induction heating a work in which each heating area is symmetrically divided,
A heating coil is configured by connecting coils arranged corresponding to each heating area of the workpiece,
By providing means for detecting the positional deviation between the heating coil and the workpiece in a range covered by the magnetic field generated by the heating coil, when the positional relationship between the heating coil and the workpiece is normal, Generate a symmetric magnetic field in the space, and if the positional relationship between the heating coil and the workpiece deviates from the normal state, the heating coil breaks the symmetry of the magnetic field generated in the space ,
Each coil is arranged corresponding to each heating area of the work, a capacitor and a heating coil are connected to a power source, and power is supplied from the power source to the heating coil,
A heating coil that detects a positional shift as a change in current or a change in impedance by means for detecting a positional shift by monitoring the impedance obtained from the current flowing from the power supply to the capacitor or the voltage generated in this current and the heating coil. For detecting the displacement between the workpiece and the workpiece .

[2] In induction heating a work in which each heating region is symmetrically divided,
Configure the heating coil by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting the positional deviation between the heating coil and the workpiece is provided,
Each coil is arranged corresponding to each heating area of the workpiece, a capacitor and a heating coil are connected to the power source, and power is supplied from the power source to the heating coil.
This is a method for detecting misalignment as a change in current or a change in impedance by means for detecting misalignment by monitoring the impedance obtained from the current flowing from the power supply to the capacitor or the voltage generated in this current and the heating coil. And
As means for detecting a positional displacement, the magnetic circuit of the ring having different permeability magnetic susceptibility and the workpiece, is provided to one of areas divided in correspondence with the heating region of the workpiece, it is formed for each coil by the magnetic flux is changed by the positional deviation in the, changes the current flowing from the power source to the capacitor,
A method for detecting misalignment between a heating coil and a workpiece .

[3] In induction heating a work in which each heating region is symmetrically divided,
Configure the heating coil by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting the positional deviation between the heating coil and the workpiece is provided,
Each coil is arranged corresponding to each heating area of the workpiece, a capacitor and a heating coil are connected to the power source, and power is supplied from the power source to the heating coil.
This is a method for detecting misalignment as a change in current or a change in impedance by means for detecting misalignment by monitoring the impedance obtained from the current flowing from the power supply to the capacitor or the voltage generated in this current and the heating coil. And
As a means for detecting misalignment, a core is provided in any one of the coils, and the magnetic flux in the magnetic circuit formed for each coil changes due to misalignment, thereby changing the current flowing from the power source to the capacitor .
A method for detecting misalignment between a heating coil and a workpiece .

[4] In induction heating a work in which each heating region is symmetrically divided,
Configure the heating coil by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting the positional deviation between the heating coil and the workpiece is provided,
Each coil is arranged corresponding to each heating area of the workpiece, a capacitor and a heating coil are connected to the power source, and power is supplied from the power source to the heating coil.
This is a method for detecting misalignment as a change in current or a change in impedance by means for detecting misalignment by monitoring the impedance obtained from the current flowing from the power supply to the capacitor or the voltage generated in this current and the heating coil. And
An auxiliary coil as a means for detecting misalignment is provided on the wiring connecting the heating coil and the capacitor, and the auxiliary coil is disposed facing the heating area of the workpiece, and the auxiliary coil is disposed in the heating area of the workpiece. by arranged opposite to a site different from the, depending on whether causes eddy currents in this region by the auxiliary coil, changes the current flowing from the power source to the capacitor,
A method for detecting misalignment between a heating coil and a workpiece .

  According to the present invention, since the means for detecting the positional deviation is provided, the positional deviation between the heating coil and the workpiece is detected as a change in current by the means for detecting the positional deviation or as a change in impedance. be able to. As a result, the heating pattern does not become asymmetric and a desired heat treatment can be performed.

It is explanatory drawing in connection with embodiment of this invention for demonstrating the method to detect the position shift of a heating coil and a workpiece | work, (a) is a top view, (b) is sectional drawing. It is explanatory drawing in connection with 1st Embodiment of this invention, and is explanatory drawing for demonstrating the positional relationship of a heating coil and a workpiece | work, Comprising: (a) is a state with a normal positional relationship, (b) is a normal positional relationship. An example of a state deviating from the state is shown in (c), and another example of a state deviating from the normal state is shown. It is explanatory drawing at the time of applying the method shown in FIG. 1 to the example of FIG. It is a figure which concerns on 2nd Embodiment of this invention and shows the example of application when a workpiece | work is a gear. The application example in the case where the work has a cup portion according to the third embodiment of the present invention is shown, (a) is a bottom view, and (b) is a cross-sectional view. The result of Example 1 and the comparative example 1 is shown, (a), (b), (c) is a graph which shows the relationship between the fall width of the heating coil with respect to a workpiece | work, current change rate, impedance change rate, and voltage change rate, respectively. It is. The result of Example 2 and the comparative example 2 is shown, (a), (b), (c) is a graph which shows the relationship between the height of a level | step difference, a current change rate, an impedance change rate, and a voltage change rate, respectively. In order to verify the detection method according to an embodiment of the present invention, it is a diagram modeling the flow of magnetic flux generated by a heating coil with a gap core. It is a block block diagram of the well-known monitoring apparatus currently disclosed in patent document 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

〔concept〕
A method for detecting a positional deviation between a heating coil and a workpiece according to an embodiment of the present invention (hereinafter simply referred to as “detection method”) is performed when induction heating is performed on a workpiece in which heating regions are divided so as to be symmetrical. Used for. Now, the workpiece is divided into a plurality of heating areas according to a symmetry plane, a symmetry axis, and other symmetrical standards, and the shape and dimensions of the coil are set corresponding to each heating area, and the heating coil is configured by connecting each coil. Suppose that The entire heating area in the workpiece is a set of divided heating areas. On the other hand, the shape and size of the coil are set corresponding to the shape and size of each heating region, and the heating coil is configured by connecting the coils in series or in parallel. In order for the entire heating region of the workpiece to have symmetry, it is necessary to generate a symmetric magnetic field by the heating coil. The heating coil is designed to generate a symmetric magnetic field, and it is detected by this detection method whether or not a positional deviation between the workpiece and the heating coil has occurred.

  The concept of this detection method is that a means for detecting the positional deviation between the heating coil and the workpiece by the current sensor 21 shown in FIG. 9 (hereinafter referred to as “means for detecting the positional deviation”) is used by the heating coil. By arranging in a range where the generated magnetic field substantially extends, when the positional relationship between the heating coil and the workpiece is normal, the heating coil generates a symmetric magnetic field in the surrounding space including the workpiece, and the heating coil and the workpiece. When the positional relationship with is deviated from the normal state, the heating coil intentionally breaks the symmetry of the magnetic field generated in the space. By providing a means for detecting the positional deviation, it is possible to detect a positional deviation such as a lateral deviation between the heating coil and the workpiece, which has been difficult in the past. Conventionally, a symmetric magnetic field is generated and the eddy current flows when the positional deviation is within an allowable range, whereas an symmetric magnetic field is generated when the positional deviation occurs and the eddy current flows. Although a change occurred, it was difficult to detect as a whole because the portions where a large amount of eddy current flowed and the portions where a small amount of eddy current flowed were offset. In this detection method, a means for detecting a positional deviation is provided so as not to cancel out due to an increase or decrease in eddy current.

  As a specific detection method, as described above, means for detecting misalignment is provided, and the monitoring device 20 shown in FIG. 9 is used to interpose a capacitor 12 in the high-frequency inverter 11 as a power source. Connect the heating coil. Then, when induction heating is performed by supplying electric power from the high-frequency inverter 11, the current flowing in the wiring between the power source and the capacitor 12 is monitored, and is performed depending on whether or not the current is out of a certain range. Here, the lateral displacement does not mean that the gap between each workpiece of the heating coil is out of a predetermined range, but the coil and the opposed surface of the workpiece to be induction-heated thereby are allowed. Even if the gap between the coil and the workpiece is within the allowable range, such as when the coil slides beyond the range or when the opposing surface of the coil and the workpiece is not substantially parallel, the induction heated area loses symmetry. Means the state.

  It should be noted that a current transformer 13 is preferably interposed between the capacitor 12 and the heating coil. This is because impedance matching is achieved and power is easily transmitted from the power source to the heating coil. In this case, the capacitor 12 and the power source are connected in parallel to the primary coil 13 a of the current transformer 13, and the heating coil is connected to the secondary coil 13 b of the current transformer 13. But you may make it connect a heating coil and a capacitor | condenser (not shown) with respect to the secondary coil 13b in series. The monitoring device 20 used in the embodiment of the present invention is not limited to that shown in FIG. 9, and may be changed or improved as appropriate in the implementation, or may be the same in equivalent circuit as FIG. 9. Absent.

  FIG. 1 is an explanatory diagram for explaining a detection method according to an embodiment of the present invention, in which (a) is a plan view and (b) is a cross-sectional view. FIG. 1 shows a case where a workpiece is a cylindrical body and there is a region where induction heating is performed in a ring shape on the inner peripheral surface thereof.

  It is assumed that the work 30 is symmetric about the axis and has a cylindrical shape as shown in FIG. 1, for example, and the cylindrical inner peripheral surface is set as a heating region. In this case, since the heating region is symmetric about the axis, the heating coil 40 is also designed to generate a magnetic field that is symmetric about the axis along the heating region. When the positional relationship between the workpiece 30 and the heating coil 40 is in a normal state, the heating coil 40 generates a symmetric magnetic field, so that the heated region is also symmetric. However, even if the positional relationship between the work 30 and the heating coil 40 deviates from a normal state, the heating coil is not changed in a magnetic field including the arrangement space of the work 30 even if the space in which the heating coil 40 is arranged is changed. The total amount of eddy current generated by 40 is also difficult to change.

  Therefore, in the present detection method, by providing a means for detecting misalignment, when the positional relationship between the workpiece 30 and the heating coil 40 is out of the normal state, the magnetic field generated by the heating coil 40 is The positional relationship is different from that in the normal state to make it asymmetric, and the total amount of eddy current generated by the heating coil 40 is changed. The total amount of eddy current is changed by detecting the current flowing in the wiring between the high-frequency inverter 11 and the matching capacitor 12 using the high-frequency heating device 10 and the monitoring device 20 shown in FIG.

  This will be described more specifically assuming that the workpiece 30 has the cylindrical shape shown in FIG. In the workpiece 30 as shown in FIG. 1, it is assumed that the heating region 31 is divided into a plurality of regions such as one region 31a and the other region 31b with the symmetry surface 32 interposed therebetween as a symmetrical reference surface. . One coil 41a is formed along the shape of one region 31a, the other coil 41b is formed along the shape of the other region 31b, and the one coil 41a and the other coil 41b are connected to each other. A heating coil 40 is configured. In the heating coil 40, one coil 41a and the other coil 41b are circumferentially arranged on a coil base 44, and a symmetry plane 42 as a reference plane is equidistant from the one coil 41a and the other coil 41b. It has become. The coil 41a and the coil 41b are connected in series. A core 43a is circumferentially attached to the coil base 42 above and below one coil 41a, and a core 43b is circumferentially attached to the coil base 42 above and below the other coil 41b.

When the heating region 31 is ring-shaped and one heating region 31a and the other heating region 31b are opposed to each other with the symmetry surface 32 in between, the reference surface 32 of the heating region 31 and the symmetry surface of the heating coil 40 42 is out of the same range, that is, even if the workpiece 30 and the heating coil 40 are displaced in the axial direction, the measured values of the current I _o and impedance described with reference to FIG. There is no noticeable effect compared to.

Therefore, means 50 for detecting a positional deviation is provided in any of the divided areas of the work 30. The means 50 for detecting misalignment has a magnetic permeability different from that of the workpiece 30, for example. As this means 50, as shown in FIG. 1, a ring body 55 a made of a material different from the material of the work 30 is arranged at the upper end of a cylindrical body as the work 30. Thereby, when the symmetrical surface 32 of the workpiece | work 30 and the symmetrical surface 42 of each coil 41a, 41b of the heating coil 40 have shifted | deviated up and down, the eddy current produced by one coil 41a and the other coil 41b Is different from the eddy current generated by. That is, due to the vertical displacement between the workpiece 30 and the heating coil 40, the symmetry plane 32 of the workpiece 30 and the symmetry plane 42 of the heating coil 40 are out of the same range, and the current is detected using the monitoring device 20 shown in FIG. A displacement can be detected as a change in I ₀ .

  Here, the means 50 for detecting misalignment is not limited to the one (disturbance) provided in any of the divided areas of the workpiece 50, and is provided in any one of the coils constituting the heating coil, for example. 9 is an auxiliary coil provided on the wiring that connects the secondary coil 13b and the heating coil shown in FIG. 9 and generates eddy current in the workpiece, for example, an auxiliary coil. Also good. Details of these will be described later.

Whether the positional relationship between the heating coil and the workpiece has deviated from the normal state is determined by connecting the heating coil to the high frequency inverter 11 as a power source via a capacitor 12 as shown in FIG. When induction heating is performed by supplying power, the current I ₀ flowing from the high-frequency inverter 11 to the capacitor 12 and the heating coil is monitored. In addition, it may be performed by monitoring the impedance obtained from the coil voltage V _coil / current I ₀ .

[First Embodiment]
FIG. 2 relates to the first embodiment of the present invention, and is an explanatory diagram for explaining the positional relationship between the heating coil and the workpiece, where (a) shows a normal positional relationship and (b) shows a positional relationship. An example of a state in which the relationship is out of a normal state is shown, and (c) shows another example of a state in which the positional relationship is out of a normal state.

  In FIG. 2, as exemplified in FIG. 1, a case where the workpiece 30 is a cylindrical body and a circumferential groove 33 is provided on the inner peripheral surface of the cylindrical body is taken as an example. Two circumferential grooves 33 are formed, an upper groove 33a and a lower groove 33b, but there may be more than that. In this case, the heating region has a substantially circular arc in cross section and has a ring shape in the circumference. The heating coil 40 includes upper and lower two-stage coils 41 a and 41 b and is disposed in the hollow of the work 30.

  In a state where the positional relationship between the workpiece 30 and the heating coil 40 is normal, as shown in FIG. 2A, the cross-sectional arc of the heating coil 40 is virtually in the upper groove 33a and the lower groove 33b of the heating region of the workpiece 30, respectively. In addition, the heating coil 40 is arranged so that the upper coil 41a and the lower coil 41b are symmetrical with each other, and the upper surface 41a and the lower groove 41b are symmetrical with each other. Surface 32 is in the same range. This is a normal state.

  However, as shown in FIG. 2B, when the symmetry plane 42 of the heating region and the symmetry plane 32 of the heating coil 30 deviate from the same range and shift up and down, for example, the symmetry plane 42 becomes a symmetry plane as illustrated. When the distance is lower than the distance d by 32, the region where the upper groove 33a is heated is larger than the lower groove 33b, and the positional relationship between the workpiece 30 and the heating coil 40 deviates from the normal state. Even if the heat treatment is performed in such a situation, the magnitude of the current flowing from the high-frequency inverter as the power source to the heating coil 40 does not change significantly compared to the case of the normal positional relationship shown in FIG. No significant difference is observed in the value of the current sensor 21 of the monitoring device 20 shown in FIG.

Further, as shown in FIG. 2C, when the work 30 is slightly inclined and the symmetry plane 42 of the heating coil 40 and the symmetry plane 32 of the heating region are not substantially parallel, the upper groove 33a and the lower groove 33b are heated. The region is not uniform in the circumferential direction. Therefore, even if the heat treatment is performed, in each of the upper groove 33a and the lower groove 33b, a range around the axis of the workpiece 30, for example, a region at the central angle θ is smaller in a heated region, whereas the central angle is 180 °. The heating region becomes large at the position of + θ. However, even if the induction heating process in such a situation, the magnitude of the current I _o flowing from the high-frequency inverter as a power source is a significant change as compared with the case of the appropriate positional relationship shown in FIG. 2 (a) Therefore, there is no significant difference in the value of the current sensor 21 of the monitoring device 20 shown in FIG.

  Therefore, in the first embodiment, even if the positional relationship is not normal as shown in FIGS. 2B and 2C, a significant difference occurs in the current flowing from the high-frequency inverter as a power source. In any one of the symmetry plane 32 related to the heating region in the workpiece 30 and the symmetry plane 42 related to the heating coil 40, the eddy current induced in the workpiece 30 is slightly different from one side to the other side with respect to the symmetry plane 32. A metal ring body is arranged so that the induction magnetic field is slightly asymmetrical between the symmetry planes 32 and 42. Since this ring body can detect the positional deviation as a change in coil current or impedance, the means 50 for detecting the positional deviation is the ring body. The means 50 for detecting the displacement may be disposed in each of the divided areas of the work 30, that is, in any one of the two areas divided by the symmetry plane 32. When the desired heating region has a circumferential shape, the ring body preferably has an endless circumferential shape. This is because it is determined whether or not it is uniformly heated around the axis. It is only necessary that the metal body be disposed in any one of the two regions divided by the symmetry plane 32 at a position that affects the magnetic field generated by the heating coil 40.

  FIG. 3 is an explanatory diagram when the method shown in FIG. 1 is applied to the example of FIG. In the example of FIG. 2, a ring body 50a made of copper is used as the means 50 for detecting misalignment, and either one of the two regions divided by the symmetry planes 32 and 42, FIG. In this example, the ring body 50a is arranged at the upper end of the cylindrical workpiece 30. When the cylindrical workpiece 30 shown in the figure is induction-heated by the heating coil 40, since the lid-like workpiece pressing member 60 is conventionally placed on the upper end of the workpiece 30, the ring body 50a is attached to the upper end of the cylindrical workpiece 30. The ring body and the workpiece 30 are both pressed by the workpiece pressing member 60 from above.

[Second Embodiment]
FIG. 4 is a diagram illustrating an application example in the case where the work is a gear according to the second embodiment of the present invention. The heating area of the work 70 is a groove 73 in which a gear trough part 70 a and a crest part 70 b are continuously formed, and one area and the other area are two inclined parts 73 a and 73 b forming the groove 73. In this case, the inclined portion 73a and the inclined portion 73b are opposed to each other by a symmetry plane 72 that bisects the valley portion 70a.

When such a groove 73 is induction-heated, a heating coil 80 is one in which one coil 81a and the other coil 81b each having a portion facing the inclined portion 73a and the inclined portion 73b are connected in series. It is used. Therefore, in applying the present invention, as means 85 for detecting the positional deviation, one of the one coil 81a and the other coil 81b (the other coil 81b in the case of illustration) and the secondary coil 13b An auxiliary coil 86 is provided in the lead portion 83 connecting the two. The auxiliary coil 86 includes a wiring part 86a along the virtual inner peripheral surface of the gear, and a disturbance part 86b that can be bent from the tip of the wiring part 86a to generate an eddy current in a non-heated region of the workpiece. When a coil current flows through the disturbance part 86b via the wiring part 86a, an induced magnetic field can be generated from the disturbance part 86b to the peak part 70b. Whether the eddy current is generated by the disturbance part 86b can be determined by adjusting the dimension of the wiring part 86a according to the dimension of the groove 73 and the heating coil 80. The induction magnetic field generated by one coil 81a and the other The induced magnetic field generated by the coil 81b and the disturbance part 86 can be made different. When the position shift between the symmetry plane 72 of the workpiece section region and the symmetry plane 82 of the heating coil 80 occurs, the current I ₀ or the coil voltage is measured using the monitoring device 20 shown in FIG. A positional shift can be detected as a change in impedance obtained from V _coil / current I ₀ .

  As described above, the auxiliary coil 86 is provided as a means 85 for detecting the positional deviation on the wiring that connects the heating coil 80 and the capacitor, and is provided in a portion that generates an eddy current in the work 70.

[Third Embodiment]
FIGS. 5A and 5B relate to a third embodiment of the present invention, showing an application example in the case where the workpiece has a cup portion, where FIG. 5A is a bottom view and FIG. 5B is a cross-sectional view. The work 90 has a shaft portion 91 and a cup portion 92, and the inner peripheral surface of the cup portion 92 is a heating region. Side walls 92a, 92b, 92c are formed on the inner periphery of the cup 92 symmetrically around the axis, and the side walls 92a, 92b, 92c of each recess are induction heated. Each coil 101 is connected so that each coil 101 is disposed in each recess, thereby forming the heating coil 100. As a means 105 for detecting misalignment, a core 105 is disposed in one of the coils constituting the heating coil 100 as shown in FIG. Also in the third embodiment, since the heating region is bilaterally symmetric by the symmetry plane 93, by arranging the core 105 on one side, as in the first and second embodiments, as a change in the current _Io or impedance, The bias of the heating coil 100 can be detected.

  In this way, the workpiece 90 is divided into a plurality of regions according to the symmetry axis of the entire heating region, the symmetry plane for each heating region, or other symmetry criteria, and the heating coil 100 corresponds to each region of the workpiece 90. In the case where the terminal 101 is connected, the core 105 is provided in any one of the coils 101 as a means for detecting misalignment.

Next, the embodiment of the present invention will be described in more detail with reference to examples.
As shown in FIG. 3, the heating head is arranged in the hollow of the cylindrical workpiece 30 so that the symmetry plane 42 of the heating coil 40 and the symmetry plane 32 of the heating region of the workpiece 30 coincide with each other. Then, the copper ring body 50a was arrange | positioned at the upper end of the workpiece | work 30, and it covered with the workpiece pressing member 60 from it, and the workpiece | work 30 was suppressed.

Here, the inner diameter of the workpiece was 56.75 mm and the outer diameter was 64.25 mm. Induction heat treatment was performed at a frequency of 25 k for 2 seconds. At that time, as described with reference to FIG. 9, the current _Io output from the high-frequency inverter 11 by the current sensor 21 and flowing on the wiring and the voltage generated in the heating coil 40 by the voltage sensor 22 are measured, and signal processing is performed. The impedance was obtained by dividing the measured voltage by the current by the unit 23c.

Next, in a state where the symmetry plane 42 of the heating coil 40 is lowered by 0.2 mm from the symmetry plane 32 of the heating region of the work 30, the copper ring body 50a is arranged at the upper end of the work 30 as described above, and the work holding member. 60. In this state, induction heating was performed, and the current _Io output from the inverter 11 and the impedance were obtained using the current sensor 21 and the voltage sensor 22.

Similarly, in a state where the symmetry plane 42 of the heating coil 40 is lowered by 0.4 mm and 0.6 mm in parallel to the symmetry plane 32 of the heating region of the workpiece 30, induction heating is similarly performed and output from the inverter 11. The current I _o and the impedance were obtained.

Next, as shown in FIG. 3, the heating head is disposed in the hollow of the cylindrical workpiece 30 so that the symmetry plane 42 of the heating coil 40 and the symmetry plane 32 of the heating region of the workpiece 30 coincide with each other. A step with a height of 0.2 mm was formed on one side of the lower end of 30. Then, the copper ring body 50a was arrange | positioned at the upper end of the workpiece | work 30, and it covered with the workpiece pressing member 60 from it, and the workpiece | work 30 was suppressed. In this state, induction heating was performed, and the current _Io output from the inverter 11 and the impedance were obtained using the current sensor 21 and the voltage sensor 22.

Similarly, performs induction heating as height 0.4mm on one end of the lower end of the work 30, each step of 0.6mm occurs, a current I _o output from the inverter 11 to determine the impedance.

(Comparative Example 1 and Comparative Example 2)
In Examples 1 and 2, the current I _o output from the inverter 11 by performing induction heating without placing the copper ring body 50a on the upper end of the work 30 and covering the work pressing member 60 on the upper end of the work 30; The impedance was determined.

Table 1 is a table showing the rate of change of the current I _o output from the high-frequency inverter 11 in Examples 1 and 2 and Comparative Examples 1 and 2, impedance, and voltage V _coil of the heating coil. FIG. 6 shows the results of Example 1 and Comparative Example 1, and (a), (b), and (c) show the relationship between the width of the heating coil lowered with respect to the workpiece, the current change rate, the impedance change rate, and the voltage change rate, respectively. It is a graph which shows. FIG. 7 shows the results of Example 2 and Comparative Example 2, and (a), (b), and (c) are graphs showing the relationship between the height of the step and the current change rate, impedance change rate, and voltage change rate, respectively. is there. The vertical axis of FIGS. 6A and 7A is the current change rate, the vertical axis of FIGS. 6B and 7B is the impedance change rate, and FIGS. 6C and 7C. The vertical axis is the voltage change rate, the horizontal axis in FIGS. 6A to 6C is the width of the heating coil lowered with respect to the workpiece, and the horizontal axis in FIGS. 7A to 7C is generated at one of the lower ends of the workpiece. This is the height of the step.

  As can be seen from Table 1 and FIGS. 6A to 6C, the ring body 50 a is arranged as in the first embodiment as the symmetry plane 42 of the heating coil 40 is lowered with respect to the symmetry plane 32 of the workpiece 30. The current change rate increases linearly and the impedance change rate decreases linearly. However, when the ring body 50a is not arranged as in Comparative Example 1, the current change rate and the impedance change rate are increased. There was no significant trend. In both cases of Example 1 and Comparative Example 1, the coil voltage change rate was almost constant.

  As can be seen from Table 1 and FIGS. 7A to 7C, when the symmetry surface 32 of the workpiece 30 is inclined with respect to the symmetry surface 42 of the heating coil 40, the ring body 50 a is arranged as in the second embodiment. In this case, the current change rate increases linearly and the impedance change rate decreases linearly. However, when the ring body 50a is not arranged as in Comparative Example 2, the current change rate and the impedance change rate are There was no significant trend. In both cases of Example 2 and Comparative Example 2, the voltage change rate was almost constant.

  Therefore, by comparing Examples 1 and 2 and Comparative Examples 1 and 2, it was found that the height deviation of the work 30 can be detected as a change in current and impedance by arranging the ring body 50a. .

  Examine the reason for the change in the measured value. When performing induction heating, the copper ring body 50a also generates an eddy current with respect to the interlinkage magnetic flux. However, since the resistivity is small, the amount of heat generated by the copper ring body 50a is small. Although the ring body 50a does not have the action of collecting magnetic flux, that is, the action of drawing the lines of magnetic force, an eddy current flows through the ring body 50a. In the induction heating under the condition that the position of the heating coil 40 is lowered, the amount of magnetic flux interlinked with the copper ring body 50a is reduced according to the amount of movement of the heating coil 40 from the reference position (the amount of movement). It is presumed that the magnetic flux interlinking with the work 30 increases as much as it becomes closer and a large amount of current flows, resulting in a change in the current value.

Here, this detection method will be verified. FIG. 8 is a diagram in which the flow of magnetic flux generated by the heating coil is modeled with a gap-type magnetic core in order to verify the detection method according to the embodiment of the present invention. As shown in FIG. 8, consider a magnetic circuit comprising a magnetic path having a transmittance μ _i , a cross-sectional area S, a uniform length Li, and a gap having a transmittance μ ₀ and a length Lg (= d). When μ _i and μ ₀ are the magnetic permeability in the magnetic path and the magnetic permeability in the air, respectively, the magnetic resistance Rm of the magnetic path and the magnetic resistance Rs of the air gap are obtained by the following equations, respectively.
Rm = Li / μ _i S
Rs = Lg / μ ₀ S
Assuming that the magnetic flux in the magnetic circuit is Φ, and the current I flows when the conductor is wound in the magnetic path with N turns, the following equation is established.
RmΦ + RsΦ = NI
Therefore,
Φ = NI / (Rm + Rs)
Holds. Therefore, if the gap Lg increases, the magnetic resistance Rs of the air gap increases and the magnetic flux in the magnetic circuit decreases. For example, when this is applied to the first embodiment, the gap between the Cu ring body 50a and the heating coil 40, that is, the air gap increases when the heating coil 40 is lowered from the specified position. The generated magnetic flux is reduced and the generated eddy current is also reduced. For this reason, the influence of canceling out the magnetic flux of the heating coil 40 is reduced, and further, the amount of interlinkage magnetic flux increases as the heating coil 40 becomes closer to the workpiece 30, and the current increases. On the other hand, when the heating coil 40 is lowered from the specified position without providing the Cu ring body 50a, one coil 41a is close to the work, and the other coil 41b is moved away from the work. There is no effect. Therefore, the magnetic flux density does not change.

  As described above, in the embodiment of the present invention, the distribution of the generated magnetic flux is made slightly asymmetric during induction heating, whereby the positional relationship between the workpiece and the heating coil is obtained by the monitoring device 20 shown in FIG. In particular, it is possible to determine whether or not the degree of coupling between the workpiece and the heating coil is appropriate.

  Although the embodiments of the present invention have been described above, the present invention can be implemented with appropriate modifications within the scope of the present invention. For example, when carrying out the present invention, means for detecting misalignment is provided according to the shape of the workpiece and its heating area.

  In the present invention, the workpiece is divided into one region and the other region with the reference plane in between, and the heating coil is connected by connecting one coil and the other coil along the shape of the divided region. This is used when a heating coil is connected to a power source via a capacitor and power is supplied from the power source to the heating coil for induction heating of the workpiece. At that time, a means for detecting the bias of the heating coil, that is, a means for detecting a positional deviation is provided in either the heating coil or the workpiece or the space in which they are arranged, and the current flowing from the power source to the capacitor Alternatively, the impedance obtained from this current and the voltage generated in the heating coil is monitored. By providing means for detecting misalignment, the bias of the heating coil with respect to the heating area of the workpiece, that is, misalignment, is detected depending on whether the current and impedance to be monitored are within a certain range. .

  For example, the heating area of the workpiece is the peripheral surface of the inside or outside of the cylindrical body, and one area and the other area are vertically divided by a reference plane that intersects the hollow axis of the cylindrical body. In the case where each section has a ring shape, a metal body may be provided at the upper end of the cylindrical body as a means for detecting misalignment.

  For example, when the heating area of the workpiece is a side wall portion that forms a plurality of depressions on the inner and outer peripheral surfaces of the cup body, the core is disposed so as to face the side wall portion as a means for detecting misalignment. It may be attached to any one of the coils constituting the heating coil.

  For example, when the heating area of the workpiece is a part or all of a groove formed by continuously forming a trough and a peak of the gear, and one area and the other area are two inclined portions forming a groove. As a means for detecting misalignment, an auxiliary coil may be connected in series to one of the lead portions of one coil and the other coil. The auxiliary coil is composed of a wiring portion along the virtual inner peripheral surface of the gear and a bent portion bent from the tip of the wiring portion, that is, a disturbance portion.

30: Work 31: Heating area 31a, 31b: Area 32: Symmetrical surface 33: Groove 33a: Upper groove 33b: Lower groove 40: Heating coil 41a, 41b: Coil 42: Coil symmetrical surface 43a, 43b: Core 50: Position shift Means for detecting 50a: ring body 60: work pressing member 70: work 70a: mountain 70b: valley 72: symmetry plane 73a, 73b: inclined part 73: groove 80: heating coil 81a, 81b: coil 83: lead Portion 85: Means for detecting displacement 86: Auxiliary coil 86a: Wiring portion 86b: Disturbing portion 90: Work piece 91: Shaft portion 92: Cup portion 92a, 92b, 92c: Side wall portion 93: Symmetrical surface 100: Heating coil 101: Coil 105: Means for detecting misalignment (core)

Claims (4)

In induction heating a workpiece in which each heating area is symmetrically divided,
Configure the heating coil by connecting coils disposed to correspond to each heating region before Symbol workpiece,
A means for detecting a positional deviation between the previous SL heating coil and pre-Symbol workpiece, wherein the Rukoto provided in a range field produced spans the heating coil, the positional relationship is a normal state of the said heating coil workpiece Symmetry of the magnetic field generated by the heating coil in the space when the heating coil generates a symmetric magnetic field in a space including the workpiece and the positional relationship between the heating coil and the workpiece is out of a normal state. To break down ,
And disposed corresponding pre SL each coil in the heating region before Symbol work, power of 20 from the power source to the heating coil by connecting a capacitor and a pre-Symbol heating coil to the power source,
By monitoring the impedance obtained from the voltage generated in the current or the current and the previous SL heating coil flows Previous Symbol capacitor before SL power, as a means changes or changes in impedance of the current due to the order to detect the leading SL positional deviation to detect the previous Symbol position deviation,
A method for detecting misalignment between a heating coil and a workpiece. In induction heating a workpiece in which each heating area is symmetrically divided,
A heating coil is configured by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting a positional deviation between the heating coil and the workpiece is provided,
Each coil is disposed in correspondence with each heating region of the workpiece, a capacitor and the heating coil are connected to a power source, and power is supplied to the heating coil from the power source,
By monitoring the current flowing from the power source to the capacitor or the impedance obtained from the current and the voltage generated in the heating coil, the position shift is detected as a change in current or a change in impedance by means for detecting the position shift. A method of detecting,
A ring having a different permeability magnetic susceptibility and the work as a means to detect the positional deviation, provided in any one of areas divided in correspondence with the heating region of the workpiece,
A method for detecting misalignment between a heating coil and a workpiece, wherein a current flowing from the power source to the capacitor is changed by changing a magnetic flux in a magnetic circuit formed for each coil due to the misalignment. In induction heating a workpiece in which each heating area is symmetrically divided,
A heating coil is configured by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting a positional deviation between the heating coil and the workpiece is provided,
Each coil is disposed in correspondence with each heating region of the workpiece, a capacitor and the heating coil are connected to a power source, and power is supplied to the heating coil from the power source,
By monitoring the current flowing from the power source to the capacitor or the impedance obtained from the current and the voltage generated in the heating coil, the position shift is detected as a change in current or a change in impedance by means for detecting the position shift. A method of detecting,
A core as a means for detecting the displacement is provided in any of the coils,
A method for detecting misalignment between a heating coil and a workpiece, wherein a current flowing from the power source to the capacitor is changed by changing a magnetic flux in a magnetic circuit formed for each coil due to the misalignment. In induction heating a workpiece in which each heating area is symmetrically divided,
A heating coil is configured by connecting each coil arranged corresponding to each heating area of the workpiece,
A means for detecting a positional deviation between the heating coil and the workpiece is provided,
Each coil is disposed in correspondence with each heating region of the workpiece, a capacitor and the heating coil are connected to a power source, and power is supplied to the heating coil from the power source,
By monitoring the current flowing from the power source to the capacitor or the impedance obtained from the current and the voltage generated in the heating coil, the position shift is detected as a change in current or a change in impedance by means for detecting the position shift. A method of detecting,
An auxiliary coil as a means for detecting the displacement is provided on the wiring connecting the heating coil and the capacitor,
While disposed opposite the heating coil in the heating region of the workpiece, by arranging to face a different site from the previous SL auxiliary coil before Symbol heated region of the previous SL workpiece, said the pre-Symbol auxiliary coil depending whether cause eddy currents to the site, to change the current flowing from the power source to the capacitor, the position deviation detecting method of the heating coil and the workpiece.

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