JPH01233365A - Magnetization system for magnetic particle flaw detection of running steel material - Google Patents

Abstract

PURPOSE:To achieve a higher flaw detection performance against a bending of a steel material, by a method wherein an exciting power command value of a magnetizer is computed from an output signal of a distance measuring means and an exciting power of the magnetizer is controlled from the exciting power command value to keep a surface magnetic field of the steel material almost constant. CONSTITUTION:A distance to a steel material, namely, a billet 1 is measured with a distance sensor 3 disposed near a magnetizing coil 2 and a distance measurement signal is sent to a numerical conversion circuit 4, which computes an exciting power according to a table prepared from a distance signal to attain the intensity of a billet surface magnetic field set with a magnetic field intensity setter 6. The circuit 4 controls a power adjuster 7 by a computed value to adjust a supply power to the magnetizer 2. Thus, the intensity of a magnetic field at the billet 1 part becomes almost constant regardless of a bending thereof, thereby achieving a higher flaw detection performance against the bending of the billet 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetization system for magnetic particle flaw detection that detects surface flaws in steel materials (for example, billets) in a running state.

[Prior Art] Methods for magnetizing steel materials for magnetic particle testing include the pole spacing method, the five-through coil method, and the axial method. FIG. 2(a) illustrates the concept of the spacing method, FIG. 2(b) illustrates the through-coil method, and FIG. 2(Q) illustrates the concept of the axial passing method.

For flaw detection during running, the interpole method and through-coil method are used.

The above magnetization methods are used depending on the target surface flaw. When targeting scratches in the longitudinal direction of steel materials, the interpolation method is used.
When targeting scratches in the @ direction, the through-coil method is used. Moreover, when scratches in all directions are to be targeted, both are combined.

For flaw detection performance, it is important to maintain a constant distance between the billet and the magnetic pole or coil. In particular, the pole-to-pole type magnetizing device is
When the gap with the billet changes, the magnetic field strength on the billet surface changes significantly.

Regarding the interpolar type magnetization device, a device has been proposed in which the magnetization device mechanically follows the positional fluctuation of the steel material. FIG. 3 shows a "tracking device for a magnetizing device" disclosed in Japanese Patent Application Laid-Open No. 54-151088.

1 is a billet, 2 is an interpolar type magnetizing device, and 11a.

11b is a magnetization device 2 and a guide roller 12a.

The cylinders 12a and 12b that support and push up the billet 12b are guide rollers provided to maintain a predetermined distance between the billet 1 and the magnetization device 2.

In this follow-up device, the cylinder 11a.

When a working fluid of a predetermined pressure is supplied to 11b, the guide rollers 12a and 12b are pressed against the steel material 1, and the distance between the steel material 1 and the magnetization device 2 is kept constant.

[Problems to be Solved] However, the above-described tracking device has the following problems.

(1) Since the weight of the magnetization device is large, the tracking device becomes large and complicated.

(2) If the tracking device has a simple structure, the tracking performance will be poor and the flaw detection performance will be degraded.

The present invention aims to solve the above-mentioned problems.The present invention aims to solve the above-mentioned problems.
The purpose of this study is to obtain a magnetization system for magnetic particle testing of steel materials.

[Means for Solving the Problems] The magnetization system for magnetic particle testing of steel materials according to the present invention includes a distance measuring means that measures the distance between the steel material and the magnetization device and outputs a signal, and an output signal of the distance measuring means. The present invention is characterized in that it is provided with a numerical conversion circuit that calculates the excitation power command amount of the magnetization device based on the excitation power command amount, and a power regulator that controls the excitation power of the magnetization device based on the excitation power command amount.

[Working Coordination] Most of the bends in the steel material subjected to magnetic particle testing are at the ends, and the majority of the entire length is straight.

On the other hand, even if a magnetizing device has an iron core, a space is included in the magnetic circuit, so the design of the iron core is not critical, and the rating is determined primarily by the heat resistance of the excitation coil. Therefore,
Short-term overloads can be applied without fear of magnetic saturation.

The present invention has been made from the above point of view, and includes a means for measuring the distance between the steel material and the magnetizing device, and a numerical conversion that calculates the degree of multiplication of excitation power from the distance signal from the measuring means using a table given in advance. Depending on the circuit, for example, when the distance between the steel material magnetization devices increases, the excitation power is increased to keep the magnetic field strength on the surface of the steel material constant.

[Example] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Note that the reference numerals already mentioned indicate the same parts, and a description thereof will be omitted.

FIG. 1 is a block diagram of a magnetization system for magnetic particle testing of steel materials as an example, and 3 is a distance measuring means for measuring the distance to the steel material without contact and outputting the measured value as a signal. The sensor 4 is a numerical conversion circuit which is given the relationship between the distance signal value and the required excitation power in advance and outputs the distance signal value as an excitation power command, and when the excitation power is constant, the magnetization device 2 and the billet 1 A distance magnetic field strength conversion table 5 obtained by actually measuring how the surface magnetic field strength of the billet 1 changes due to a change in the distance between and a subtraction circuit that calculates the difference between the two.

7 is a power regulator that adjusts the AC power input value to the magnetization device 2 according to a command from the numerical conversion circuit 4, and 8 is an AC power source.

The magnetization system of this example is configured as follows,
It works like this:

With the distance sensor 3 placed near the magnetizing coil 2,
The distance to the billet 1 is measured and a distance measurement signal is sent to the numerical conversion circuit 4. Here, as the distance sensor 3, a known eddy current type or optical type can be suitably used. In the numerical conversion circuit 4, the excitation power is calculated from the distance signal using a table prepared in advance so that the billet surface magnetic field strength is set by the magnetic field strength setting device 6, and the power regulator 7 is controlled based on the calculated value. The power supplied to the magnetization device 2 is adjusted so that the magnetic field strength on the surface of the billet 1 remains approximately constant even if the billet 1 is bent.

In this manner, the magnetization system for magnetic particle testing of steel materials according to the present embodiment makes it possible to maintain good magnetic particle testing conditions by keeping the magnetic field strength of the billet portion substantially constant even if there is bending.

In this embodiment, the bending of the billet 1 in the vertical direction has been explained, but when there is a bending in the left and right directions, as shown in FIG. By providing a similar device, good flaw detection results can be obtained. In the symbols in FIG. 4, the subscript "a" indicates the left side device, the subscript "a" indicates the right side device, and the numerical part indicates the same function as the numerical symbol in FIG.

[Effects of the Invention] The magnetization system for magnetic particle testing of steel materials according to the present invention includes a distance measuring means for measuring the distance between the steel material and the magnetizing device and outputting a signal, and excitation of the magnetizing device from the output signal of the distance measuring means. A numerical conversion circuit that calculates the power command amount and a power regulator that controls the excitation power of the magnetization device based on the excitation power command amount are provided, and the steel material can be easily adjusted even if the steel material is bent without any mechanically moving parts. Since the surface magnetic field is kept almost constant, (1) the flaw detection performance for bending steel material is improved;

(2) No mechanical follow-up device is required, simplifying the equipment.

(3) Significant economic effects can be obtained due to reduced investment costs and improved operation, such as safety due to fewer moving devices near the visual observer.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a magnetization system for magnetic particle testing of steel materials as an example, Figures 2 (a) to (c) are perspective views showing the concept of the magnetization method, and Figure 3 is a conventional magnetization system. FIG. 4 is a schematic cross-sectional view of the tracking device of the apparatus, and is a block diagram of a magnetization system for magnetic particle testing of steel materials as another embodiment. 1... Billet, 2... Magnetizer, 3
・・・・・・Distance sensor as distance measuring means, 4...
... Numerical conversion circuit, 5 ... Distance magnetic field strength conversion table, 6 ... Magnetic field strength setting device, 7 ...
... Power regulator, 8... AC power supply. Patent applicant: Kobe Steel, Ltd. Representative Patent attorney: Fu Kobayashi Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a magnetization system for magnetic particle testing of steel materials in which the steel material is magnetized while running for magnetic particle testing, there is a distance measuring means for measuring the distance between the steel material and the magnetization device and outputting a signal, and a distance measuring means for measuring the distance between the steel material and the magnetization device and outputting a signal. A steel material characterized by being provided with a numerical conversion circuit that calculates the excitation power command amount of the magnetization device from the output signal of the steel material, and a power regulator that controls the excitation power of the magnetization device based on the excitation power command amount. Magnetization system for magnetic particle flaw detection while traveling.