JPS60169758A - Method for scattering magnetic powder in magnetic powder flaw detection - Google Patents

Abstract

PURPOSE:To reduce noise caused by residual water when ultrasonic flaw detection performed in a post process without leaving a necessary amount on more of scattered water on the surface of a steel plate, by scattering water containing a magnetic powder in a mist form in performing the magnetic powder flaw detection of the surface of the steel plate. CONSTITUTION:Water containing a magnetic powder is scattered to a steel pipe 1 being a material to be subjected to flaw detection. In this case, a magnetic powder slurry (for example, containing 1-0.5g/l of a pure iron powder) is pumped up from a magnetic powder slurry tank 7 by a sprayer 4 and sprayed through a flexible pipe 3. At this time, the size and spray angle of sprayed particles are regulated by the caliber or open angle of the orifice part of a nozzle 2. Therefore, because water to be scattered is uniformly scattered in a mist form, a min amount of a water film is formed to the surface to be subjected to flaw detection in magnetic powder flaw detection and noise by residual water is generated at the time of ultrasonic flaw detection in a post-process and the reliability of flaw detection is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for dispersing magnetic particles for detecting magnetic particles on the surface of steel materials.

(B) Prior Art Conventionally, when scattering magnetic particles to perform magnetic particle flaw detection on the inner surface of the end of a tube, a so-called shower set magnetic particle scattering method has been used. According to such a method, more sprayed water than necessary remains on the inner surface of the pipe material. Therefore, in the ultrasonic flaw detection performed in the post-process, the large amount of sprayed water covers the pipe material surface as residual water, so the reflection of the flaw signal from the pipe material surface is smaller than the water film noise signal, so it is masked by the noise component. As a result, it was difficult to perform accurate flaw detection.

Therefore, conventional methods require a step to remove this residual water, which has the disadvantage of making the work complicated.

Furthermore, since the water removal device used to remove this residual water is very expensive, there is also the drawback that the cost required for flaw detection is high.

(c) Purpose The present invention has been made to eliminate the above-mentioned drawbacks, and when scattering magnetic particles for magnetic particle flaw detection on the inner surface of the end of a tube, more water than necessary is sprayed onto the inner surface of the tube. The purpose is to provide a method for dispersing magnetic particles that does not leave any residue.

Another object of the present invention is to provide a magnetic powder dispersion method that eliminates the step of removing residual water, saves work, and reduces costs.

(D) Structure The magnetic particle dispersion method for magnetic particle flaw detection according to the present invention is characterized in that magnetic particles are dispersed on the surface of a steel material by spraying spray water containing magnetic particles in the form of a mist.

(P) Embodiment FIG. 1 is an explanatory diagram for explaining an embodiment of the magnetic powder dispersion method according to the present invention, FIG. 2 is an enlarged sectional view of the nozzle 2 in FIG. 1, and FIG. FIG. 2 is an explanatory diagram schematically showing the configuration.

Reference numeral 1 denotes a pipe material to be inspected for flaws, and magnetic powder is scattered on the inner surface of the pipe material. A nozzle 2 is attached to one end of a flexible pipe 3, which will be described later, and is located on the center line of the tube material 1. A sectional view thereof is shown in FIG. In FIG. 2, the spray water disk 10 that has passed through the flexible pipe 3
Enter the central nook 12 through the small hole ll, and enter the nozzle tip 8.
is injected outward from the opening 9 of.

3 is a flexible pipe, the other end of which is attached to the sprayer main body 4. The sprayer body 4 includes a piston 42 and a chamber 43 driven by an electromagnetic device 41 to apply pressure to the spray water and deliver it to the nozzle tip. The water pressure is appropriately adjusted by varying the stroke of the piston 42. The stroke can be varied by operating the voltage regulator 45 with the lever 44 and appropriately setting the voltage applied to the electromagnetic device 41. Further, the spraying time is determined by the voltage regulator 45 ON-OFF.
The timer 47 controls the relay switch 46, which controls the relay switch 46, to arbitrarily set the timer 47. Further, 48 is a motor that rotationally drives the flexible pipe 3 connected to the sprayer main body 4 via a rotary joint 49.
The power is transmitted to the pipe 3 via the sprocket 50, chain 52, and sprocket 51. Furthermore, 53
．． 54 is a check valve for preventing backflow of sprayed water.

On the other hand, the lower end of the liquid suction hose 6 is inserted into the magnetic powder liquid connector 7 . The magnetic powder liquid tank 7 is charged with a magnetic powder liquid in which 1 to 0.5 g of magnetic powder (for example, pure iron) is mixed with water II2, and this magnetic powder liquid is constantly stirred.

Next, the operation of the embodiment having the above-described configuration will be explained.

By the operation of the electromagnetic piston in the sprayer main body 4, the spray water sucked up from the magnetic powder liquid tank 7 and given a constant pressure is sent to the nozzle tip via the flexible pipe 3. This i&cloth water is then sprayed in the form of mist at the tip of the nozzle.

On the other hand, the size of the spray particles and the spray angle can be set to appropriate values by varying the diameter and opening angle of the nozzle opening 9.

Further, since the flexible pipe 3 is rotationally driven by the motor 48, the spray water is sprayed more evenly.

In the above-mentioned embodiment, the sprayed water is made into a mist using an electromagnetic piston, but the present invention is not limited to this. A well-known air one-type atomizer that uses the pressure drop during flow to create a mist is also suitable.

It goes without saying that the material to be detected is not limited to the pipe-shaped material described in the above-described embodiments, but may also be a flat material with the same effect.

Further, the nozzle shape and the spraying direction can be changed and selected as appropriate depending on the shape of the material to be tested.

(f) Effects Since the present invention sprays spray water in the form of mist, it is possible to form the minimum amount of water film on the flaw detection surface that allows magnetic particle flaw detection.

Therefore, during ultrasonic flaw detection in the post-process, there is no noise caused by residual water, the reliability of flaw detection is improved by uniform spraying in the form of mist, and there is no need for a process to remove residual water. Moreover, the work becomes easier, and as a result, the cost required for flaw detection can be reduced, and in particular, the running cost of spray water can be reduced.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining an embodiment of the magnetic powder dispersion method according to the present invention, Fig. 2 is an enlarged sectional view of the nozzle 2 in Fig. 1, and Fig. 3 is an explanatory diagram in which the structure of the sprayer main body is abbreviated. It is. 1... Pipe material, 2... Nozzle, 3... Flexible pipe, 4... Sprayer main body, 6... Liquid suction pipe, 7... Magnetic powder liquid tank, 8°.・Nozzle tip, 9... Nozzle opening. Patent applicant Nippon Steel Corporation Shimadzu Corporation Shimadzu Metal Industries Co., Ltd. Agent Patent attorney Takaharu Ohnishi Figure 1 Figure 2

Claims (1)

[Claims] (1) A magnetic particle dispersion method for magnetic particle flaw detection, characterized in that magnetic particles are dispersed on the surface of a rope by spraying spray water containing magnetic particles in the form of a mist.