JP4525475B2 - Surface processing method - Google Patents

Description

  The present invention relates to a surface processing method in which a high-pressure water stream containing cavitation bubbles is made to collide with the surface of a workpiece, and compressive stress is applied to the surface of the workpiece, deburring, cleaning, or the like.

When applying compressive stress to a metal material, removing burrs generated in the processed part of the metal material, or cleaning dirt adhering to the surface of the metal material, a high-pressure water stream containing cavitation bubbles is applied to the surface of the metal material. There is a way to hit. That is, it is possible to perform a process such as applying a compressive stress to the surface of the metal material by a large impact pressure generated locally when the cavitation bubbles collapse on the surface of the metal material.
And the technique which gives a compressive stress to a metallic material by injecting a high-pressure water stream toward a metallic material in the air is disclosed (refer patent document 1). In this technique, a two-layer water flow composed of a high-speed water flow and a low-speed water flow surrounding the high-speed water flow is injected in the air. As a result, cavitation bubbles are generated in the two-layer water flow due to the speed difference between the high-speed water flow and the low-speed water flow.

However, in the above technique, in order to apply a sufficient pressure to the metal material, the distance between the nozzle and the metal material needs to be relatively large. This is because cavitation bubbles are sufficiently generated at a position where a certain distance from the nozzle is secured.
As a result, it may be difficult to perform the surface processing of the metal material in a narrow space. Further, the flow of the two-layer water stream becomes unstable as it moves away from the nozzle, and it becomes difficult to concentrate the two-layer water stream at a desired position and apply the two-layer water stream. For this reason, it may be difficult to efficiently perform surface processing on necessary portions of the metal material.

Japanese Patent No. 2957976

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a surface processing method capable of efficiently performing surface processing at a desired position.

In the present invention, a two-layer nozzle having a first jet port and a second jet port surrounding the first jet port is disposed in the water,
A high-speed water stream is ejected from the first jet outlet toward the air, and a low-speed water stream slower than the high-speed water stream is jetted from the second jet outlet to the air.
A two-layer water stream composed of the high-speed water stream and the low-speed water stream surrounding the high-speed water stream includes cavitation bubbles,
The surface processing method is characterized in that the two-layer water flow is applied to the surface of a workpiece placed in the air (Claim 1).

Next, the effects of the present invention will be described.
In the surface treatment method, the two-layer nozzle is used to form a two-layer water stream composed of a high-speed water stream ejected from the first ejection port and a low-speed water stream ejected from the second ejection port. As a result, cavitation bubbles are generated in the two-layer water flow due to a speed difference and a pressure difference between the high-speed water flow and the low-speed water flow. The cavitation bubbles collapse near the surface of the workpiece. At this time, an extremely large impact pressure is locally generated, and a sufficiently large compressive stress can be applied to the surface of the workpiece. Further, if burrs are generated on the surface of the workpiece, the burrs can be removed, and if dirt is attached, the dirt can be washed.

  And in this invention, a two-layer water flow is injected from the said two-layer nozzle arrange | positioned in water. Thereby, cavitation bubbles can be generated in the two-layer water flow at an early stage, that is, cavitation collapse energy can be generated at a position close to the nozzle tip of the two-layer nozzle. Therefore, even if the distance between the workpiece and the two-layer nozzle is reduced, it is possible to sufficiently perform surface processing using cavitation bubbles (see Example 2 described later).

  As a result, it is possible to perform the surface processing of the workpiece in a narrow space. In addition, since the two-layer water flow that is close to the two-layer nozzle and has a stable flow can be applied to the surface of the workpiece, the two-layer water flow can be applied in a concentrated manner at a desired position. Therefore, surface processing can be efficiently performed on a necessary portion of the workpiece.

  As described above, according to the present invention, it is possible to provide a surface processing method that can efficiently perform surface processing at a desired position.

The surface processing method of the present invention (Claim 1), for example, applies compressive stress (peening) to the surface of the workpiece, removes burrs generated on the surface of the workpiece, This is used for cleaning dirt adhering to the surface.
The two-layer nozzle is preferably arranged at a position where the distance between the nozzle tip of the two-layer nozzle and the water surface is 15 mm or less.
In this case, the impact force when the two-layer water flow hits the surface of the workpiece can be sufficiently secured, and the surface processing of the workpiece can be performed more efficiently.

When the distance between the nozzle tip and the water surface exceeds 15 mm, it is difficult to improve the impact force exerted by the two-layer water flow on the surface of the workpiece, thereby improving the effect of the surface processing of the workpiece. May be difficult.
Further, from the viewpoint of sufficiently exerting the effect of the present invention that high processing ability can be ensured even if the distance between the two-layer nozzle and the workpiece is reduced, the distance between the nozzle tip and the water surface is, for example, 2 mm. The above is preferable.

The surface processing method may be a method of peening, deburring, or cleaning the surface of the workpiece (claim 3).
In this case, peening, deburring, or cleaning can be efficiently performed at a desired position on the workpiece.

Moreover, the said to-be-processed body shall consist of a metal, resin, or a ceramic (Claim 4).
In this case, surface processing can be efficiently performed at a desired position in the workpiece made of metal, resin, or ceramic.

Example 1
A surface processing method according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a two-layer nozzle 1 having a first outlet 11 and a second outlet 12 surrounding the first outlet 11 is disposed in water.
The high-speed water stream 21 is jetted from the first jet port 11 toward the air, and the low-speed water stream 22 that is slower than the high-speed water stream 21 is jetted from the second jet port 12 to the air.
The two-layer water stream 2 composed of the high-speed water stream 21 and the low-speed water stream 22 surrounding the high-speed water stream 21 includes cavitation bubbles 23.
The two-layer water stream 2 is applied to the surface of the workpiece 3 made of metal disposed in the air.

  The two-layer nozzle 1 has a high-pressure water nozzle 131 connected to the first jet port 11 and a low-pressure water nozzle 132 connected to the second jet port 12. The low-pressure water nozzle 132 is coaxially disposed so as to surround the high-pressure water nozzle 131. Note that the high-pressure water nozzle 131 and the low-pressure water nozzle 132 may be eccentric from each other. In this case, the distribution of cavitation decay energy can be changed.

The high-pressure water nozzle 131 is provided with an orifice 133 at the first jet port 11. In addition, a first taper portion 134 whose diameter decreases toward the tip is formed in the outer portion of the orifice 133.
The low-pressure water nozzle 132 is formed with a second taper portion 135 whose diameter decreases toward the tip at the outer portion of the first taper portion 134.
High pressure water 210 is supplied to the high pressure water nozzle 131, and low pressure water 220 is supplied to the low pressure water nozzle 132. The supply pressure of the high-pressure water 210 is, for example, 10 to 50 MPa, and the supply pressure of the low-pressure water 220 is, for example, 0.05 to 0.15 MPa.

Further, the two-layer nozzle 1 is disposed in the stored water 42 stored in the water tank 41. And the 1st spout 11 and the 2nd spout 12 have faced the vertically upper direction, and are located in the stored water 42, ie, the lower part of the water surface 421.
Specifically, the two-layer nozzle 1 is arranged at a position where the distance d between the nozzle tip 14 of the two-layer nozzle 1 and the water surface 421 is 15 mm or less.

  As shown in FIG. 2, high-pressure water 210 is supplied from the high-pressure pump 53 to the high-pressure water nozzle 131 of the two-layer nozzle 1, and low-pressure water 220 is supplied from the low-pressure pump 54 to the low-pressure water nozzle 132. The high-pressure pump 53 and the low-pressure pump 54 are arranged in supply water 52 stored in a water supply tank 51 different from the water tank 41. The supply water 52 is supplied to the two-layer nozzle 1 as high-pressure water 210 and low-pressure water 220 by a high-pressure pump 53 and a low-pressure pump 54, respectively.

Further, the workpiece 3 to be processed is disposed in the air above the two-layer nozzle 1. That is, the workpiece 3 is fixed to a fixing jig 61 disposed above the water tank 41. The fixing jig 61 and the two-layer nozzle 1 are indirectly fixed via a frame or the like of a processing apparatus (not shown). Further, a scattering prevention cover 62 for preventing scattering of water and metal scraps is disposed around the fixing jig 61 to which the workpiece 3 is fixed.
Then, the two-layer water stream 2 is applied to a desired portion of the workpiece 3 for an appropriate time. Moreover, when the part which wants to surface-treat exists continuously, the two-layer water flow 2 can be applied, moving the to-be-processed body 3 relatively with respect to the two-layer nozzle 1. FIG.

Next, the function and effect of this example will be described.
In the surface treatment method, the two-layer nozzle 1 is used to form a two-layer water stream 2 composed of a high-speed water stream 21 ejected from the first ejection port 11 and a low-speed water stream 22 ejected from the second ejection port 12. To do. As a result, cavitation bubbles 23 are generated in the two-layer water stream 2 due to a speed difference and a pressure difference between the high-speed water stream 21 and the low-speed water stream 22. The cavitation bubbles 23 collapse near the surface of the workpiece 3. At this time, an extremely large impact pressure is locally generated, and a sufficiently large compressive stress can be applied to the surface of the workpiece 3. Moreover, if the burr | flash has arisen on the surface of the to-be-processed body 3, this burr | flash can be removed, and if dirt has adhered, this dirt can be wash | cleaned.

  And in this example, the two-layer water flow 2 is injected from the said two-layer nozzle 1 arrange | positioned in water. Thereby, the cavitation bubble 23 can be generated in the two-layer water flow 2 at an early stage, that is, at a position close to the nozzle tip 14 of the two-layer nozzle 1. Therefore, even if the distance L between the workpiece 3 and the two-layer nozzle 1 is reduced, the surface processing with the cavitation bubbles 23 can be sufficiently performed (see Example 2).

  As a result, the surface processing of the workpiece 3 can be performed in a narrow space. Further, since the two-layer water stream 2 having a short distance L from the two-layer nozzle 1 and a stable flow can be applied to the surface of the workpiece 3, the two-layer water stream 2 can be applied in a concentrated manner at a desired position. . Therefore, it is possible to efficiently perform surface processing on necessary portions.

  Further, since the distance d between the nozzle tip 14 of the two-layer nozzle 1 and the water surface 421 is 15 mm or less, a sufficient impact force can be ensured when the two-layer water flow 2 collides with the surface of the workpiece 3. The surface processing of the workpiece 3 can be sufficiently performed.

  As described above, according to this example, it is possible to provide a surface processing method that can efficiently perform surface processing at a desired position.

(Example 2)
In this example, as shown in FIG. 3, the characteristics of the processing capability of the surface processing method of the present invention were evaluated.
As the surface processing method of the present invention, the method shown in Example 1 was used. In addition, as a comparative example, the same surface processing treatment was performed using the same two-layer nozzle 1 as in Example 1 in a state of being disposed in the air.

As the workpiece 3, a plate-like body made of aluminum (AL1050) was used. Moreover, the pressure of the high pressure water 210 was 30 MPa, the pressure of the low pressure water 220 was 0.06 MPa, and the two-layer water flow 2 was applied to the workpiece 3 for 180 seconds continuously. In the method of the present invention, the distance d between the nozzle tip 14 and the water surface 421 is 2 mm.
And the amount of erosion when the distance L between the nozzle tip 14 of the two-layer nozzle 1 and the workpiece 3 was changed was measured. This amount of erosion was evaluated as processing capacity. That is, it can be said that the larger the amount of erosion, the higher the processing energy by the two-layer water flow 2 including the cavitation bubbles 23 and the higher the processing capacity.

The measurement results are shown in FIG. In FIG. 3, the results plotted when the method of the present invention is used are plotted with ●, and the results when the method of the comparative example is used are plotted with ◆.
As can be seen from FIG. 3, in any of the methods, the amount of erosion decreases if the distance L is too small or too large. And, as the amount of erosion of the peak, the present invention and the comparative example are equivalent, but for the distance L between the nozzle tip 14 and the workpiece 3 at that time, the case of using the method of the present invention, It becomes about 5mm shorter.

  From this result, it can be seen that according to the present invention, the cavitation bubbles 23 can be generated in the two-layer water stream 2 at an early stage, that is, at a position close to the nozzle tip 14 of the two-layer nozzle 1. And compared with a comparative example, the distance L between the to-be-processed object 3 and the two-layer nozzle 1 can be made small, and the surface processing process by the cavitation bubble 23 can be performed efficiently.

(Example 3)
In this example, as shown in FIG. 4, the relationship between the distance d between the nozzle tip 14 and the water surface 421 and the surface processing capability is examined. Evaluation of the processing ability was performed by measuring the amount of erosion by the same method as in Example 2 above.
At this time, the distance L between the nozzle tip and the workpiece was 30 mm. And the distance d was changed to 0-20 mm, and the amount of erosion was measured. This measurement was performed three times for each level, and the average was taken.
The measurement results are shown in FIG.
As can be seen from FIG. 4, as the distance d increases, the amount of erosion decreases, that is, the surface processing capability decreases. It can also be seen that if the distance d is 15 mm or less, sufficient surface processing capability can be obtained.

Sectional explanatory drawing which shows the surface processing method in Example 1. FIG. FIG. 3 is a perspective explanatory view showing a surface processing method in the first embodiment. FIG. 6 is a diagram showing measurement results in Example 2. FIG. 6 is a diagram showing measurement results in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Two-layer nozzle 11 1st jet nozzle 12 2nd jet nozzle 14 Nozzle tip 2 Two-layer water flow 21 High-speed water flow 22 Low-speed water flow 23 Cavitation bubble 3 Work piece 41 Water tank 42 Reserved water

Claims (4)

A two-layer nozzle having a first outlet and a second outlet surrounding the first outlet is disposed in the water;
A high-speed water stream is ejected from the first jet outlet toward the air, and a low-speed water stream slower than the high-speed water stream is jetted from the second jet outlet to the air.
A two-layer water stream composed of the high-speed water stream and the low-speed water stream surrounding the high-speed water stream includes cavitation bubbles,
A surface processing method, wherein the two-layer water flow is applied to a surface of a workpiece placed in the air.   2. The surface processing method according to claim 1, wherein the two-layer nozzle is disposed at a position where a distance between a nozzle tip of the two-layer nozzle and a water surface is 15 mm or less.   3. The surface processing method according to claim 1, wherein the surface processing method is a method of peening, deburring, or cleaning the surface of the workpiece.   The surface processing method according to claim 1, wherein the workpiece is made of metal, resin, or ceramic.

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