JPH0545335A - Magnetic particle inspecting method using magnetization by pulse current - Google Patents

Abstract

PURPOSE:To shorten the inspecting time and to reduce the inspecting cost by performing magnetization in X, Y and Z axes continuously in one process during the magnetic particle inspection by a pulse current enabling detection of a minute flaw. CONSTITUTION:A work 1 to which a liquid of fluorescent magnetic particles is applied by a shower 3 is sent forward on a conveyor 2. When the work passes through an X-axial magnetic field coil 8, the work is magnetized by the magnetic field of a pulse current in the X axis direction and therefore, fluorescent magnetic particles are collected to a flaw Fx orthogonal to the X axis direction. Thereafter, the work 1 is proceeded for a time interval T to pass a Y-axial magnetic field generating coil 9 and further for a time interval T to pass through a Z-axial magnetic field generating coil 10. At this time, the work is magnetized similarly and fluorescent magnetic particles are collected to flaws Fy, Fz orthogonal to the Y, Z axes, respectively. The time interval T is generally 0.5-2.0 seconds. As the work magnetized in each of the X, Y, Z axial reaches an inspecting chamber 11, a black light 12 casts ultraviolet rays to the work, and accordingly the fluorescent magnetic particles adhered to the flaws come to appear by a fluorescent agent, which are confirmed by eyes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse magnetized magnetic powder flaw detection method for detecting fine flaws in a metal part made of a ferromagnetic material in one step.

[0002]

2. Description of the Related Art Wet magnetic particle flaw detection methods have been widely used for defect inspection of metal parts made of a ferromagnetic material. That is, if the inspected metal part (hereinafter referred to as the work) is magnetized by an appropriate method, the magnetic resistance of the flaws such as scratches and cavities inside the surface or near the surface is larger than that of other sound parts. The magnetic flux is curved at the defective portion, and a part of the magnetic flux leaks into the air to generate a leakage magnetic flux.

A defect can be detected by detecting the leakage magnetic flux. As a method for detecting the defect, a fluorescent magnetic powder liquid obtained by mixing magnetic powder in water or kerosene with a necessary fluorescent agent or rust preventive agent has been used as a detection method. When the work is magnetized in the state where it is applied by showering or dipping, the magnetic flux adheres to the defective portion of the work due to the leakage magnetic flux. A method of confirming and subsequently demagnetizing the work was performed.

As a method of magnetizing a work in the above-mentioned wet magnetic particle flaw detection method, a. Coil magnetization b. Direct current magnetization c. There are three methods of multiple alternating magnetization, and further as a magnetizing current, a. Exchange b. Single-phase half-wave c. Single-phase full wave d. Three-phase full wave e. DC f. There are 6 types of pulse current, which are selected according to the work condition.

[0005] Detection sensitivity of defects of the workpiece are large with respect to the direction of the wound to be perpendicular to the direction of the magnetic flux is magnetized, when the workpiece do not know this for certain what the direction of the wound It is desirable to perform the inspection twice or more by changing the direction of the magnetic flux, preferably three times by the magnetic flux in the X-axis direction, the Y-axis direction and the Z-axis direction.

In the case of the multiple alternating magnetization method, the magnetic fields in the X-axis, Y-axis, and Z-axis directions can be simultaneously generated by utilizing the phase shift of the input current, so that there is an advantage that the inspection can be completed in one step. The types of magnetizing current are limited to alternating current and single-phase half-wave,
The accuracy of surface flaw detection in the case of alternating current can be detected only with a flaw having a width of 10 to 30 microns and a depth of 40 microns or more, and in the case of single-phase half-wave, only a flaw larger than that in the case of alternating current can be detected. It is not suitable for detecting minute scratches.

For detection of minute scratches, pulse current magnetization by one-wave rectification or capacitor discharge capable of detecting scratches with a width of 2 to 3 microns has been conventionally performed, and this pulse current magnetization cannot change the phase. Since this is not possible, only a magnetic field in one direction is generated, and therefore flaw detection is required three times by magnetic flux in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0008]

The problem to be solved is that the flaw detection by the pulse current magnetization is performed three times by the magnetic field in the X-axis direction, the magnetic field in the Y-axis direction and the magnetic field in the Z-axis direction. Since it is necessary, it takes time and expense, and the inspection cost is high.

[0009]

According to the present invention, a workpiece coated with a magnetic powder liquid by showering or dipping is magnetized by a pulse current magnetic field in the X-axis direction and magnetized by a pulse current magnetic field in the Y-axis direction. It is a pulse magnetized magnetic particle flaw detection method in which magnetization by a pulse current magnetic field in the axial direction is performed at time intervals to inspect flaws in all directions in one step.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing the timing of pulse current magnetization in the X-axis direction, the Y-axis direction, and the Z-axis direction, FIG. 2 is a diagram showing the magnetization direction with respect to a workpiece, and FIG. 3 is a diagram of a wet magnetic particle flaw detector for implementing the present invention. It is a figure which shows an example.

In FIG. 3, (1) is a work, which is on the conveyor (2) and moves in the direction of the arrow. (3) is a shower, and the fluorescent magnetic powder solution (5) is pumped up by the shower pump (6) from the fluorescent magnetic powder solution tank (4) installed below the conveyor (2) and placed on the conveyor (2). Then, the fluorescent magnetic powder liquid (5) is applied to the workpiece (1) passing therethrough and the fluorescent magnetic powder liquid (5) is applied to the workpiece (1). The fluorescent magnetic powder liquid tank (4) is provided with a stirring pump (7) to stir the fluorescent magnetic powder liquid so that the magnetic powder does not precipitate.

(8) is an X-axis direction magnetic field generating coil, (9)
Is a Y-axis direction magnetic field generating coil, and (10) is a Z-axis direction magnetic field generating coil, and each has a pulse current (Px), (Py), (Pz) of 60 cycles with a time interval (T) as shown in FIG. After being energized for 1/120 seconds, the X-axis direction magnetic field generating coil (8) has an X-axis direction magnetic field, the Y-axis direction magnetic field generating coil (9) has a Y-axis direction magnetic field, and the Z-axis direction magnetic field generating coil (10). A magnetic field in the Z-axis direction is generated.

When the work (1) coated with the fluorescent magnetic powder (5) by the shower (3) moves on the conveyor (2) and passes through the X-axis direction magnetic field generating coil (8), as shown in FIG. It is magnetized by the magnetic field in the X-axis direction shown, and the fluorescent magnetic powder gathers in the scratch (Fx) orthogonal to the X-axis direction, and subsequently the work (1) advances for a time interval (T) to generate the next magnetic field in the Y-axis direction. Similarly, when passing through the coil (9), it is magnetized by the magnetic field in the Y-axis direction to collect the fluorescent magnetic particles on the scratch (Fy) orthogonal to the Y-axis direction, and then the work (1) is separated by the time interval (T). The next Z-axis magnetic field generating coil (1
Similarly, when it passes through 0), it is magnetized by the magnetic field in the Z-axis direction, and the fluorescent magnetic particles gather at the scratch (Fz) orthogonal to the Z-axis direction.

In this case, the time interval (T) is such that the fluorescent magnetic powder liquid does not drip from the work (2) and is uniformly attached to the surface, and the magnetization in the three directions of the X-axis, the Y-axis and the Z-axis is completed. At the same time, it is necessary to set the timing so that the fluorescent magnetic powder on the scratched part that is magnetically attached by the previous magnetization does not fall off. With the technology based on experience, the speed of the conveyor (2) or the magnetic field generation in the X-axis / Y-axis / Z-axis direction is generated. Coil (8), (9), (1
It is set by adjusting the interval of 0), and the work (1)
It is usually about 0.5 to 2.0 seconds, though it varies depending on the size and shape.

Reference numeral (11) is an examination room, and a black light (12) consisting of a dark room for irradiating ultraviolet rays is attached to the upper part, and the work (1) magnetized in each of the X-axis, Y-axis and Z-axis directions is provided. When it reaches the inspection room (11) on the conveyor (2), the black light (12) irradiates it with ultraviolet rays to expose the fluorescent magnetic powder magnetically adhered to the scratched portion due to the brightness of the fluorescent agent. Check.

Reference numeral (13) is a demagnetizing coil, and when the visual inspection is completed and the work (1) placed on the conveyor (2) and coming out of the inspection room (11) passes through the demagnetizing coil (13). It is demagnetized and the magnetic particle flaw detection is completed. After the completion, the work (1) may be dried to remove the fluorescent magnetic powder remaining on the surface. In the figure, (14) is a conveyor drive motor.

An example of a method for detecting flaws while moving a work has been described above. However, in the case of a stopped work, the X-axis direction magnetic field generating coil, the Y-axis direction magnetic field generating coil, and the Z-axis direction magnetic field generating coil are used. It is installed in combination at the same place, and each magnetic field generation coil is energized in sequence at a time interval using a timer to generate magnetic fields in the X-axis direction, Y-axis direction, and Z-axis direction for flaw detection of workpieces. is there.

[0018]

According to the pulse current magnetized magnetic powder flaw detection method according to the present invention described above, magnetic particle flaw detection by a pulse current capable of detecting fine flaws can be performed in three directions of X axis, Y axis and Z axis. By performing the process continuously in one step, the inspection time can be significantly shortened and the inspection cost can be reduced as compared with the conventional three-time process.

[Brief description of drawings]

FIG. 1 is a diagram showing a magnetization timing of the present invention.

FIG. 2 is a diagram showing a magnetization direction with respect to a work.

FIG. 3 is a schematic view showing an example of a wet magnetic particle flaw detector for practicing the present invention.

[Explanation of symbols]

 1 Workpiece (metal part to be inspected) 2 Conveyor 3 Shower 4 Fluorescent magnetic powder liquid tank 5 Fluorescent magnetic powder liquid 6 Shower pump 7 Stirring pump 8 X-axis magnetic field generating coil 9 Y-axis magnetic field generating coil 10 Z-axis magnetic field generating coil 11 Inspection room 12 Black light 13 Demagnetizing coil 14 Conveyor drive motor X, Y, Z Magnetic field direction T Time interval Px, Py, Pz Pulse current Fx, Fy, Fz Damage

Claims (1)

[Claims] 1. A metal component to be inspected coated with a magnetic powder liquid is magnetized by a pulse current magnetic field in the X-axis direction, magnetized by a pulse current magnetic field in the Y-axis direction, and magnetized by a pulse current magnetic field in the Z-axis direction. Is conducted at a time interval to inspect for flaws in all directions in one step.