JP5937834B2 - Magnetizer for magnetic flaw detection - Google Patents

Description

  The present invention relates to a magnetizing device for magnetic flaw detection for inspecting, using magnetism, whether or not parts of various devices such as a power generating turbine rotor are flawed.

  In general, as described in Patent Document 1 below, a magnetizing apparatus for magnetic flaw detection includes an electromagnet having a core made of a magnetic material and a magnetizing coil wound around the core, and an alternating current for magnetizing the magnetizing coil. AC output means for magnetization for output and a changeover switch are provided. When the changeover switch is switched from the OFF state to the ON state, the magnetization AC output means outputs the magnetization AC to the magnetization coil. Then, the core material is magnetized, and the object to be inspected in contact with the core material is magnetized. Thereafter, a magnetic flaw inspection is performed. After completion of the magnetic flaw inspection, the output of the magnetizing AC to the magnetizing coil is stopped, and the electromagnet is removed from the object to be inspected.

  Residual magnetism exists in the inspection object after the magnetic flaw detection inspection. In order to demagnetize this residual magnetism, a demagnetizer is used. As described in Patent Document 2, the demagnetizer is configured to generate a magnetism that decays with time by passing a decaying alternating current through a magnetic coil of an electromagnet. The residual magnetism is demagnetized.

JP-A 63-6458 JP-A-61-34908

  When the conventional magnetic flaw detection and magnetization apparatus is used, the residual magnetism of the object to be inspected must be demagnetized by using a demagnetizer every time the magnetic flaw inspection is completed. That is, a demagnetizer is required. For this reason, there existed a problem that equipment cost increased. In addition, a demagnetizer must be installed on the object to be inspected for each magnetic flaw inspection, and there has been a problem that it takes time to install the demagnetizer.

In order to solve the above problems, the present invention provides a magnet made of a magnetic material, an electromagnet having a magnetizing coil wound around the core, and a magnetizing AC output means for outputting magnetizing AC to the magnetizing coil. And a changeover switch that can be switched between a first state and a second state, and when the changeover switch is switched from the first state to the second state, the magnetization AC output means In the magnetizing device for magnetic flaw detection that outputs a magnetizing AC to the coil, the magnetizing coil further comprises a demagnetizing AC output means for outputting a demagnetizing AC that attenuates with time, and the changeover switch is moved from the second state to the magnetizing coil. When switched to the first state, the output of the magnetizing AC from the magnetizing AC output means to the magnetizing coil is stopped, and at the same time, the magnetizing coil outputs from the magnetizing AC output means to the magnetizing coil. Is characterized in that use alternating current is output.
In this case, the magnetization AC output means has AC generation means for generating AC, the demagnetization AC output means has the AC generation means and attenuation means, and the changeover switch has the first switch. When the state is switched from the second state to the second state, the magnetization AC output means generates the magnetization AC based on the alternating current generated from the alternating-current generation means, and the changeover switch is moved from the second state. When switched to the first state, the alternating current output from the alternating current generating means is changed to an alternating current that is attenuated over time by the attenuating means, whereby the alternating current for magnetization from the alternating current output means for magnetization to the magnetizing coil. It is desirable that the demagnetizing AC is output from the demagnetizing AC output means based on the attenuated AC.

  After completion of the magnetic flaw inspection, the changeover switch is switched from the second state to the first state. Then, simultaneously with the magnetization AC output means stopping the magnetization AC output, the demagnetization AC output means outputs the demagnetization AC to the magnetization coil. As a result, magnetism that decays with time is generated in the core material. This decaying magnetism demagnetizes the residual magnetism of the object to be inspected. Therefore, according to the magnetic flaw detection magnetizing apparatus according to the present invention, it is possible to immediately demagnetize the residual magnetism of the object to be inspected without using a demagnetizer after the magnetic flaw detection. Therefore, a demagnetizer is unnecessary, and the equipment cost can be reduced accordingly. Further, the labor required for installing the demagnetizer can be saved, and the work efficiency of the magnetic flaw inspection can be improved accordingly.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the embodiment.

The best mode for carrying out the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the magnetic flaw detection magnetizing apparatus according to the present invention includes an electromagnet 1, an AC output means 2, a main switch 3, and a changeover switch 4.

  The electromagnet 1 has a core material 11 made of a magnetic material and a magnetizing coil 12 wound around the core material 11. The core material 11 has a substantially “U” shape, and both ends thereof are brought into contact with the object to be inspected. The magnetizing coil 12 is wound around an intermediate portion of the core material 11.

  The AC output means 2 includes a battery 21 such as a lead storage battery or a lithium battery. When the main switch 3 is switched from the off state to the on state, the direct current of the battery 21 is output to the booster circuit 22. The booster circuit 22 boosts the voltage of the battery 21 to a predetermined voltage. The voltage of the battery 21 is, for example, 6 to 12V, and the voltage after boosting is, for example, about 140V. The direct current boosted by the booster circuit 22 is output to the amplifier circuit 23.

  The AC output means 2 further has a sine wave AC output means 24. The sine wave AC output means 24 is composed of a microcomputer, and includes a control means 241 and a sine wave generation circuit (AC generation means) 242. When the changeover switch 4 is switched from the off state to the on state, the control unit 241 causes the sine wave generation circuit 242 to generate a sine wave alternating current (hereinafter referred to as a magnetization sine wave alternating current) having a constant output value. The sine wave alternating current for magnetization generated by the sine wave generation circuit 242 has a low current value and voltage value. For example, the current value is about 2 to 4 A, and the voltage is about 140V. Various types of sine wave generation circuit 242 are well known, and the specific configuration is not related to the present invention. Therefore, the description of the specific configuration of the sine wave generation circuit 242 is omitted.

  The magnetization sine wave alternating current output from the sine wave generation circuit 242 is output to the amplification circuit 23. The amplifying circuit 23 amplifies the magnetization sine wave alternating current with the direct current supplied from the booster circuit 22 to obtain the magnetization alternating current. The magnetizing alternating current generated by the amplifier circuit 23 is output to the magnetizing coil 12 of the electromagnet 1. As a result, the core material 11 is magnetized. Of course, both ends of the core material 11 are brought into contact with an object to be inspected (not shown). Therefore, when the core material 11 is magnetized, the device under test is magnetized.

When the changeover switch 4 is switched from the on state ( second state) to the off state ( first state), the control means 241 is a sinusoidal alternating current (hereinafter referred to as demagnetization) that attenuates to the sine wave generation circuit 242 over time. Sine wave alternating current). The demagnetizing sine wave alternating current has the same initial value as the magnetization sine wave alternating current, but the current value attenuates below a predetermined current value over time. In this embodiment, the current value is attenuated to zero.

  The demagnetizing sine wave alternating current generated in the sine wave generation circuit 242 is output to the amplification circuit 23. The amplifying circuit 23 amplifies the demagnetizing sine wave alternating current with the direct current output from the booster circuit 22 to obtain a demagnetizing alternating current. This demagnetizing alternating current attenuates with time in response to the demagnetizing sine wave alternating current being attenuated. The demagnetizing alternating current is output to the magnetizing coil 12. Therefore, when the changeover switch 4 is switched from the on state to the off state, demagnetizing alternating current that decays with time is output to the magnetizing coil 12 instead of the alternating current for magnetization having a constant output value. Of course, the demagnetizing alternating current has the same initial value as the magnetization alternating current, and decays to zero over time. Therefore, the magnetic force generated by the electromagnet 1 is attenuated to zero over time. Thereby, the residual magnetism of the object to be inspected is demagnetized.

  As is clear from the above contents, in this magnetization flaw detection magnetizing apparatus, the control means 241, the sine wave generation circuit 242 and the amplification circuit 23 when the changeover switch 4 is in the on state constitute the magnetization AC output means, The demagnetizing AC output means is constituted by the sine wave generation circuit 242 and the amplification circuit 23 after the control means 241 and the changeover switch 4 are switched from the on state to the off state.

  The magnetizing device for magnetic flaw detection having the above configuration operates based on the flowchart shown in FIG. That is, when the main switch 3 is switched from the off state to the on state, the program starts. At the same time, the battery 21 is connected to the booster circuit 22. The booster circuit 22 boosts the direct current of the battery 21 and outputs it to the amplifier circuit 23.

On the other hand, the control means 241 determines whether or not the changeover switch 4 has been switched from the off state to the on state in step S1. As long as the changeover switch 4 is in the OFF state, step S1 is repeated.

  When the changeover switch 4 is switched from the off state to the on state, the process proceeds to step S 2, where the sine wave generation circuit 242 generates a sine wave alternating current for magnetization and outputs it to the amplification circuit 23. The amplifying circuit 23 amplifies the magnetization sine wave alternating current to obtain a magnetization alternating current, and outputs this to the magnetization coil 12. As a result, the core material 11 is magnetized, and the object to be inspected in which both ends of the core material 11 are in contact is magnetized.

Thereafter, the process proceeds to step S3. In step S3, it is determined whether or not the changeover switch 4 has been switched from the on state to the off state. If the changeover switch 4 is kept on, the process returns to step S2. That is, as long as the changeover switch 4 is kept on, the magnetizing AC is continuously output to the magnetizing coil 12. Of course, during this time, a magnetic flaw inspection is performed on the object to be inspected.

If it is determined in step S3 that the changeover switch 4 has been switched from the on state to the off state, the process proceeds to step S4. In step S4, the sine wave generating circuit 242 outputs a demagnetizing sine wave alternating current. The current value A of the demagnetizing sine wave AC is obtained by the following equation.
A = B · (N−n) / N (Formula 1)
Here, B is a current value of the sine wave alternating current for magnetization, and N is a predetermined integer or an integer input from the outside. N is an integer variable, and its initial value is 0. Therefore, immediately after the changeover switch 4 switches from the on state to the off state, the sine wave generation circuit 24 outputs the same sine wave alternating current as the magnetization sine wave alternating current as the demagnetizing sine wave alternating current. This sine wave alternating current is amplified by the amplifier circuit 23 and output to the magnetizing coil 12 as a demagnetizing alternating current.

  Next, the process proceeds to step S5. In step S5, the number obtained by adding 1 to the variable n is set as a new variable n. Therefore, the variable n is incremented by 1 every time steps S4 and S5 are executed. That is, the variable n changes to 0, 1, 2,.

  Thereafter, in step S6, it is determined whether “n = N” is satisfied. If “n ≠ N”, the process returns to step S 4, Equation 1 is executed again, and the demagnetizing AC is output to the magnetizing coil 12. Here, since (n + 1 → n) is executed during the second and subsequent executions of Equation 1, the demagnetizing AC current value output to the magnetizing coil 12 decreases each time step S4 is executed. . That is, the degaussing alternating current output to the magnetizing coil 12 is attenuated over time. When steps 4 and 5 are repeated and “n = N” is established, the program ends. When “n = N” is satisfied, the current value of the degaussing sine wave is zero, and thus the current value of the demagnetizing AC is also zero.

  As is clear from the above contents, the integer N is the number of times of attenuation AC output. Therefore, the integer N is selected to be sufficient to demagnetize the residual magnetism. Further, since the variable n is increased by “1”, the demagnetizing attenuation alternating current is attenuated by 1 / N, but may be attenuated in another manner. For example, the attenuation current may be patterned in advance. Further, the output of the demagnetizing sine wave may be stopped before “n = N” is satisfied, that is, before the current value of the demagnetizing alternating current becomes zero, and becomes sufficiently small.

  According to the magnetic flaw detection magnetizing device having the above-described configuration, when the magnetic flaw detection is completed, a demagnetizing AC is immediately output instead of the magnetizing AC. And not. Therefore, the facility cost can be reduced accordingly. In addition, since it is not necessary to install a demagnetizer on the object to be inspected, the demagnetization work efficiency can be significantly improved, and as a result, the work efficiency of magnetic flaw detection can be improved.

In addition, this invention is not limited to said embodiment, A various modification is employable in the range which does not deviate from the summary.
For example, in the above embodiment, the alternating current for magnetization and the demagnetizing alternating current are generated using the direct current battery 21 as a power source. However, the battery 21 may be a power source for only the demagnetizing alternating current, Good. In that case, when the changeover switch 4 is switched from the on state to the off state, the commercial current is turned off or the magnetization AC output means and the magnetizing coil 12 are disconnected. At the same time, the demagnetizing AC may be output to the magnetizing coil 12 by the control means 241, the sine wave generation circuit and the amplification circuit 23.
Moreover, it is good also considering the commercial current as a power supply of both magnetization alternating current and demagnetizing alternating current. In this case, when the changeover switch 4 is switched from the off state to the on state, the commercial alternating current is converted into a magnetic alternating current having an appropriate frequency and current value and output to the magnetizing coil 12. When the changeover switch 4 is switched from the on state to the off state, the magnetizing alternating current is attenuated to be a demagnetizing alternating current and output to the magnetizing coil 12.
Even when commercial AC is used as the power source, the magnetization AC output circuit (magnetization AC output means) and the demagnetization AC output circuit (demagnetization AC output means) may be separate circuits. In this case, when the changeover switch 4 is switched from the on state to the off state, the magnetization AC output circuit is turned off or the magnetizing AC output circuit and the magnetizing coil 12 are disconnected and simultaneously degaussed. The demagnetizing alternating current may be output from the alternating current output circuit to the magnetizing coil 12.
As described above, the magnetization AC and the demagnetization AC may be output by any other known method instead of the above embodiment. In short, when the changeover switch 4 is switched from the on state (second state) to the off state (first state), the demagnetizing alternating current may be output from the magnetizing alternating current to the magnetizing coil 11. .
Further, the main switch 3 can be used as a changeover switch. However, in that case, when the main switch 3 is switched from the on state (second state) to the off state (first state), the current from the battery 21 to the booster circuit 22 immediately stops. The demagnetizing alternating current cannot be output to the magnetizing coil 12. Therefore, the main switch 3 remains on until the demagnetizing AC output stops after the switching operation from the on state to the off state, and the off state after the demagnetizing AC output stops. It is necessary to configure so as to switch to
Furthermore, in the above embodiment, the sine wave that is the source of the demagnetizing AC is attenuated. However, the magnetizing AC output by the amplifier circuit 23 may be attenuated over time to be a demagnetizing AC.

DESCRIPTION OF SYMBOLS 1 Electromagnet 3 Changeover switch 11 Core material 12 Magnetization coil 21 Battery 23 Amplifier circuit 241 Control means 242 Sine wave generation circuit (AC generation means)

Claims (2)

A core material made of a magnetic material, an electromagnet having a magnetizing coil wound around the core material, a magnetizing AC output means for outputting a magnetizing AC to the magnetizing coil, and a changeover switch that can be switched between an off state and an on state When the changeover switch is switched from the off state to the on state, the magnetizing AC output means outputs the magnetizing alternating current to the magnetizing coil, and the on / off state of the changeover switch and the magnetizing ac In the magnetizing apparatus for magnetic flaw detection in which a magnetic flaw inspection is performed on an object to be inspected in an output state, and the changeover switch is switched from the on state to the off state after completion of the magnetic flaw inspection .
Demagnetizing AC output means for outputting demagnetizing AC that attenuates with time to the magnetizing coil,
When the changeover switch is switched from the ON state to the OFF state, the output of the magnetizing AC from the magnetizing AC output means to the magnetizing coil is stopped , and at the same time as the magnetizing AC output is stopped , the demagnetization is performed. Magnetizing device for flaw detection, characterized in that a demagnetizing alternating current is output from the alternating current output means to the magnetizing coil. The magnetizing AC output means has AC generating means for generating AC,
The demagnetizing AC output means has the AC generating means and attenuating means,
When the changeover switch is switched from the off state to the on state, the magnetizing alternating current generating means generates the magnetizing alternating current based on the alternating current generated from the alternating current generating means,
When the changeover switch is switched to the OFF state from the ON state, alternating the AC generating means outputs is an AC you over time attenuated by said attenuating means, thereby the magnetization from the AC output means for the magnetization At the same time the output of magnetization AC to the coil is stopped, the magnetic according to claim 1, characterized in that AC degaussing based on AC which is the damping from the degaussing AC output means Ru is output Magnetizer for flaw detection.

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