JPH05249083A - Flaw detection method by magnetic powder - Google Patents

Abstract

PURPOSE:To detect a flaw stably by a method wherein cobalt-based magnetic powders are used as magnetic pulverulent particles, they are sprayed on a magnetized object whose flaw is to be detected and the flaw is detected by the movement of the magnetic powders. CONSTITUTION:In a guide rail 8 as an object whose flaw is to be detected, a part near an arm 7 supporting the rail is easily cracked and damaged. A magnet 10 is attracted in advance to an anticipated part, and magnetic pulverulent particles are sprayed on the part. The magnetic pulverulent particles are composed of cobalt-based magnetic powders whose specific gravity is about 1 to 2; they are used together with an alcohol-based solvent, kerosene or the like whose specific gravity is about 1 to 2 after they have been put into a container such as a sprayer or the like. In addition, it is desirable that a fluorescent agent whose specific gravity is about 1 to 2 is put into the container and that a crack-anticipated part 9 is illuminated with a search light 11 such as ultraviolet rays or the like. When the cobalt- based magnetic powders are sprayed on the anticipated part 9, the magnetic powders are immediately distributed uniformly by means of the magnet 10 because their specific gravity is small and the particles are fine. The powders creep into a flaw part. Consequently, it is possible to detect the existence of an actual flaw by means of the movement of the cobalt- based magnetic powders or by means of the fluorescent agent which has been added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic powder flaw detection method in which magnetic powder particles are sprayed onto a flaw detection target of a magnetic material and the portion is magnetized to perform flaw detection.

[0002]

2. Description of the Related Art This type of magnetic particle flaw detection method has been used for a long time as one of the magnetic flaw detection methods. In particular, in consideration of work in a dark place, a fluorescent agent is mixed to make it easier to find a flaw. It has also been proposed to synthesize a fluorescent agent and magnetic powder particles as described in JP-B-48-14388.

[0003]

However, when the fluorescent agent and the magnetic powder particles are mixed with a solvent and enclosed in a spray can or the like, iron oxide having a specific gravity of 4 to 7 is generally used as the magnetic powder particles, and the specific gravity of the fluorescent agent is also used. Since they are 1 to 2, they are separated from each other due to the difference in their specific gravities, and when they are used without knowing them, magnetic powder particles are not supplied to the flaw detection part,
Or, if it is not sufficiently supplied, the flaw detection effect due to the movement cannot be expected stably.

An object of the present invention is to provide a magnetic particle flaw detection method capable of performing stable flaw detection.

[0005]

In order to achieve the above object, the present invention uses a cobalt-based magnetic powder as magnetic powder particles, sprays this on an object to be detected, magnetizes that portion, and moves the cobalt-based magnetic powder. The feature is that it is made to detect from.

[0006]

In the magnetic particle flaw detection method according to the present invention, as described above, the cobalt magnet powder is used to spray the flaw on the flaw detection object.
The specific gravity of this cobalt-based magnetic powder is as small as about 1 to 2, and the cobalt-based magnetic powder immediately penetrates into the existing flaws that are uniformly distributed on the surface of the flaw detection object. Therefore, when the same portion is magnetized, flaw detection can be easily performed from the movement of the cobalt-based magnetic powder, and a stable flaw detection effect can be expected.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an object to be inspected using a magnetic particle inspection method according to an embodiment of the present invention. Since the guide rail 8 which is an object to be inspected is susceptible to crack damage in the vicinity of the arm 7 that supports the guide rail 8, the magnet 10 is attracted to a portion expected in advance and magnetic powder particles are sprayed to the portion. These magnetic powder particles are mixed with a solvent in a container 1 such as a spray can or a sprayer,
As the magnetic powder particles, cobalt-based magnetic powder having a specific gravity of about 1 to 2 is used, and as the solvent, an alcohol solvent or kerosene having a specific gravity of about 1 to 2 is used. Further, in a preferred embodiment, a fluorescent agent having a specific gravity of about 1 to 2 is further mixed in the container 1, and the crack occurrence prediction part 9 is set to a search light 11 such as an ultraviolet ray.
Illuminate with.

When the cobalt-based magnetic powder is sprayed on the cracking-predicted portion 9 by the above-mentioned method, the specific gravity of the cobalt-based magnetic powder is small and the particles are fine. Invade. Therefore, it is possible to detect the presence of an actual flaw from the movement of the cobalt-based magnetic powder or the fluorescent agent mixed together.

[0009]

As described above, according to the present invention, the cobalt-based magnetic powder is used as the magnetic powder particles and is sprayed onto the flaw-detected object. Therefore, the particles are immediately uniformly distributed on the surface of the flaw-detected object and enter the flaw. Therefore, flaw detection can be performed with stable accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view of an object to be inspected using a magnetic particle inspection method according to an embodiment of the present invention.

[Explanation of symbols]

 1 Container 8 Guide Rail 9 Crack Expected Part 10 Magnet

Claims (1)

[Claims] 1. A magnetic powder flaw detection method in which magnetic powder particles are sprayed onto an object to be inspected and the portion is magnetized to detect flaws from the movement of the magnetic powder particles, wherein a cobalt-based magnetic powder is used as the magnetic powder particles. Method of flaw detection.