Cavitation treatment device and cavitation treatment method

Abstract

Provided is a cavitation treatment device for uniformly imparting a cavitation effect (such as residual stress) to the surface and deep part of a component. This cavitation treatment device is provided with: a nozzle (2) that injects a cavitation fluid (C) onto a workpiece (W); a direction switching unit (3) that changes the flow direction of the cavitation fluid (C) branched by colliding with the workpiece (W) so that the cavitation fluid (C) is surrounded inside the direction switching unit (3); a drive device (4) having a rotating shaft (4a) and rotating the workpiece (W) together with the rotating shaft (4a); and a support part (5) that supports one end of the rotating shaft (4a).

Description

Technical Field

[0001] The invention relates to a cavitation treatment device and a cavitation treatment method for performing cavitation treatment on the surface of a component. Background Art

[0002] In the past, cavitation treatment was performed on high-function parts such as aircraft parts. By applying compressive residual stress to the surface of various parts and forming a dent shape, friction was relieved while retaining lubricating oil. Cavitation treatment is a general term for surface treatment, shot peening, cleaning, peeling, cutting, deburring, etc.

[0003] However, there are still many unexplained principles regarding cavitation using liquid (eg, water), and it is not easy to establish a method and device for stably controlling cavitation.

[0004] For example, a system is disclosed for surface treatment of the inner surface of a component, comprising: a tank in which the component can be positioned; a fluid in the tank, which can sink the component into the fluid when the component is positioned in the tank; a nozzle, which is immersed in the fluid and generates a cavitation fluid flow toward a first direction; and a deflection tool, which is immersed in the fluid and has a deflection surface for redirecting the cavitation fluid flow from the first direction to a second direction, and the first direction is away from the inner surface of the component and the second direction is toward the inner surface of the component. (For example, Japanese Patent Publication No. 2020-157470, hereinafter referred to as "Patent Document 1"). Summary of the invention

[0005] As shown in Patent Document 1, cavitation treatment can be performed inside a workpiece of a complex shape by changing the flow direction of the cavitation fluid using a deflection tool. However, there is still room for improvement in order to reliably impart cavitation at a target position of a workpiece to be cavitation treated.

[0006] For example, when the cavitation fluid is made to collide directly with the workpiece, or when the cavitation fluid is made to collide directly with the workpiece by simply changing the flow direction of the cavitation fluid, cavitation may be performed not at the target position of the workpiece but around the target position.

[0007] In addition, the cavitation fluid ejected from the nozzle in the liquid contains cavitation bubbles. It is known that the cavitation bubbles are temporarily retained in the liquid. Even if the cavitation fluid is collided with the workpiece in a state where the cavitation bubbles are dispersed, it is impossible to impart the best cavitation effect (residual stress, etc.) to the target position of the workpiece. That is, even if the cavitation fluid is collided with the workpiece in a state where the cavitation bubbles are dispersed, in order to impart the best cavitation effect, the number of treatments becomes large, and a large number of treatments and time are required.

[0008] Furthermore, in order to uniformly impart the cavitation effect to (the surface of) a cylindrical component, it is necessary to adjust the position of the workpiece, check the depth of the cavitation effect (residual stress), etc., which requires the number of treatments and time.

[0009] An object of the present invention is to provide a cavitation treatment device and a cavitation treatment method that can impart cavitation effects (residual stress, etc.) evenly to the surface and deep portion of a component.

[0010] A first aspect of the present invention is a cavitation treatment device having:

[0011] a nozzle that sprays a cavitation fluid toward a workpiece;

[0012] a direction switching portion that changes the flow direction of the cavitation fluid that has collided with the workpiece and branched off to surround the inner side of the direction switching portion;

[0013] a driving device having a rotating shaft and causing the workpiece to rotate together with the rotating shaft; and

[0014] A support portion supports one end of the rotating shaft.

[0015] A second aspect of the present invention is a cavitation treatment method, comprising:

[0016] By ejecting the cavitation fluid from the nozzle and causing it to collide with the upper surface of the workpiece, the flow direction of the cavitation fluid is branched,

[0017] By causing the branched cavitation fluid to collide with the side wall of the direction switching portion, the flow direction of the cavitation fluid is changed.

[0018] The flow direction of the cavitation fluid is changed by causing the cavitation fluid having changed its flow direction at the side wall to collide with the bottom of the direction switching portion.

[0019] The cavitation fluid having changed its flow direction at the bottom is caused to collide with the lower surface of the workpiece.

[0020] According to the cavitation treatment device and the cavitation treatment method of the present invention, it is possible to evenly impart cavitation effects (residual stress, etc.) to the surface and deep portion of a component. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a perspective view showing the cavitation treatment device according to the first embodiment.

[0022] Figure 2 It is a front view showing the cavitation treatment device according to the first embodiment.

[0023] Figure 3It is a front view showing the cavitation treatment device according to the second embodiment.

[0024] Figure 4A 3 is a diagram showing the test results of verification test 1.

[0025] Figure 4B It is a graph showing the test results of verification test 2.

[0026] Figure 4C It is a graph showing the test results of verification test 3.

[0027] Explanation of symbols

[0028] 1 Cavitation treatment device

[0029] 2 Nozzles

[0030] 3-direction switching unit

[0031] 4 Drive device

[0032] 5 Support

[0033] 6 Control device

[0034] C1~4 cavitation fluid

[0035] CA Cavitation bubbles

[0036] S stand-off distance

[0037] H1~3 height

[0038] W1~3 width

[0039] W Workpiece

[0040] T-tank DETAILED DESCRIPTION

[0041] Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[0042] The cavitation treatment device 1 of this embodiment performs cavitation treatment on the surface of high-function components used in the nuclear energy field, general metal components, etc. Figure 1 As shown, the cavitation treatment device 1 has a nozzle 2, a direction switching unit 3, a driving device 4 and a supporting unit 5. The nozzle 2 sprays the cavitation fluid C1 toward the workpiece W. The direction switching unit 3 changes the flow direction of the cavitation fluid C2 that collides with the workpiece W and branches. The driving device 4 has a rotating shaft 4a. The rotating shaft 4a has, for example, an axially symmetrical shape (a cylinder, a round rod, etc.), and is inserted and fixed in the center of the workpiece W. As the driving device 4 is driven, the rotating shaft 4a rotates. The supporting unit 5 is arranged at the front end of the rotating shaft 4a and supports the rotating shaft 4a.

[0043] The nozzle 2 ejects the cavitation fluid C1 supplied from a high-pressure fluid supply source (not shown). The cavitation fluid C1 collides with the upper surface of the workpiece W. Then, the cavitation fluid C1 branches and changes the flow direction. Here, the upper surface of the workpiece W is given a primary cavitation effect.

[0044] The cavitation fluid C1 collides with a position eccentric to the center of the workpiece W, whereby the velocity of the cavitation fluid C and the flow direction of the branched cavitation fluid C are stabilized. For example, the cavitation fluid C1 is eccentric to the center of the workpiece W by arranging the nozzle 2 so that an extension line of the nozzle 2 passes through a position deviated from the rotation center of the workpiece W, or by tilting the injection angle of the cavitation fluid C1 injected from the nozzle 2.

[0045] For example, when the cavitation fluid C1 is eccentric to either the left or right side relative to the center of the workpiece W, the amount of the cavitation fluid C2 branched to the eccentric side becomes larger, and the amount of the cavitation fluid C2 branched to the opposite side becomes smaller. If the amount of the cavitation fluid C2 is large, the influence on the flow direction is also large, and further, the diffusion of the cavitation bubbles CA contained in the cavitation fluid C2 can be suppressed. Therefore, the impact force of the cavitation fluid C2 can be maintained.

[0046] Furthermore, by adjusting the distance S (gap) from the nozzle 2 to the upper surface of the workpiece W, the impact force on the surface of the workpiece W changes.

[0047] The direction switching portion 3 changes the flow direction of the cavitation fluid C2 that branches out due to the collision with the workpiece W so as to be surrounded by the inner side of the direction switching portion 3. The direction switching portion 3 has a side wall 3a and a bottom 3b. The side wall 3a changes the flow direction of the cavitation fluid C2 that branches out due to the collision with the workpiece W twice. The bottom 3b changes the flow direction of the cavitation fluid C3 that changes its flow direction due to the collision with the side wall 3a three times. The direction switching portion 3 is preferably formed into a concave shape by the side wall 3a and the bottom 3b. However, even if it is not a concave shape, it can be a shape that surrounds the cavitation bubbles CA surrounding the cavitation fluid C generated when the cavitation fluid C1 collides with the upper surface of the workpiece W and the flow direction of the cavitation fluid C2 inside the direction switching portion 3.

[0048] like Figure 2 as well as Figure 3 As shown, the shape of the direction switching portion 3 is important to surround the cavitation bubbles CA around the cavitation fluid C generated when the cavitation fluid C1 collides with the upper surface of the workpiece W, and the flow direction of the cavitation fluid C2 inside the direction switching portion 3. The side wall 3a and the bottom 3b are, for example, flat or arc-shaped. Figure 2 An example in which the side wall 3a and the bottom 3b are planar is shown. Figure 3 The side wall 3a is flat and the bottom 3b is arc-shaped. Figure 2 and Figure 3In the embodiment, the flow direction of the cavitation fluid C inside the direction switching portion 3 and the collision position with the workpiece W are different.

[0049] When the direction switching portion 3 has a concave shape, heights H1 to H3 and widths W1 and W2 described below are important.

[0050] The height H3 is the height of the side wall 3 a. The height H2 is the height at which the cavitation fluid C collides with the workpiece W. By making the height H3 higher than the height H2, the cavitation fluid C2 that is branched when the cavitation fluid C1 collides with the workpiece W can be prevented from leaking to the outside (outside) of the direction switching portion 3 .

[0051] The width W1 is the width of the inner surface of the bottom 3b. The width W2 is the distance between the workpiece W and the side wall 3a in the horizontal direction. It is preferred that the cavitation bubbles CA and the cavitation fluid C2 surrounding the cavitation fluid C collide with the lower surface of the workpiece W by switching the flow direction multiple times. Therefore, the width W2 through which the cavitation bubbles CA surrounding the cavitation fluid C and the cavitation fluid C2 branched by colliding with the workpiece W pass is preferably less than the radius of the workpiece W. Thus, the cavitation fluid C can be more effectively surrounded.

[0052] For example, when the workpiece W is cylindrical, the cavitation processing position changes sequentially by the rotation of the rotating shaft 4a. The cavitation fluid C ejected from the nozzle 2 collides with the surface of the workpiece W, which can impart a primary cavitation effect to the surface of the workpiece W. Furthermore, as the workpiece W rotates, the surface imparted with the primary cavitation effect moves downward, and the cavitation bubbles CA and the cavitation fluid C4 surrounding the cavitation fluid C on the inner side of the direction switching portion 3 collide with the surface of the workpiece W again, which can impart a secondary cavitation effect to the surface of the workpiece W. That is, in addition to the primary cavitation effect, the cavitation effect can also be imparted to a deeper position of the workpiece W.

[0053] The support part 5 supports the rotating shaft 4a. The support part 5 has a rotation support mechanism inside so as not to stop the rotation of the rotating shaft 4a.

[0054] The cavitation treatment device 1 may also include a control device 6 for adjusting the amount of cavitation bubbles CA. For example, in a liquid, cavitation bubbles CA are affected by temperature changes. The control device 6 is, for example, a commercially available temperature adjustment device. The optimal temperature is, for example, 40 to 50° C. The control device 6 adjusts the temperature according to the environment in the liquid and the cavitation effect required for the workpiece W.

[0055] Next, the cavitation treatment process of this embodiment will be described.

[0056] First, the workpiece W is fixed on the rotating shaft 4a, and the conditions for the cavitation treatment such as the height of the nozzle 2 are determined. In addition, before or after the fixing operation of the workpiece W, the tank T is filled with liquid (for example, water). By performing the cavitation treatment in the liquid, the cavitation bubbles CA and the cavitation fluid C are stably surrounded, and the optimal amount of cavitation bubbles CA collides with the workpiece W, thereby obtaining the best cavitation effect.

[0057] Next, a high-pressure water supply source (not shown) is started, and the position of the nozzle 2 is fixed. Then, the cavitation fluid C1 is ejected from the nozzle 2 so as to collide with the upper surface of the workpiece W, thereby branching the flow direction of the cavitation fluid C1 (switching the first direction). In addition, by making the cavitation fluid C1 collide with a position eccentric to the center of the workpiece W, a better cavitation effect can be imparted.

[0058] Next, the branched cavitation fluid C2 collides with the side wall 3a of the direction switching portion 3 to change the flow direction of the cavitation fluid C2 (second direction switching). Then, the cavitation fluid C3 collides with the bottom 3b of the direction switching portion 3 to change the flow direction of the cavitation fluid C3 (third direction switching).

[0059] Finally, the cavitation fluid C4 is made to collide with the lower surface of the workpiece W. Thus, a primary cavitation effect (imparting residual stress on the surface) can be given to the upper surface of the workpiece W and a secondary cavitation effect (imparting residual stress on the deep part) can be given to the lower surface of the workpiece W in stages, and the compressive stress can be made to remain in a short time without applying excessive load to the workpiece W compared with the past.

[0060] Next, a verification test of the cavitation effect using the cavitation treatment device 1 according to the embodiment will be described.

[0061] (Verification Test 1)

[0062] The position of the nozzle 2 was fixed by the cavitation treatment device 1. The cavitation fluid C1 at 70 MPa supplied from a high-pressure water supply source (not shown) was directly collided with the upper surface of the verification workpiece W (stainless steel round bar) fixed to the rotating shaft 4a for 5 minutes.

[0063] Figure 4A This is the test result of verification test 1. Visual observation showed that the left surface of the workpiece W was thinly peeled off. The residual stress was measured using a commercially available residual stress measuring device, and as a result, a compressive stress of minus 400 MPa remained.

[0064] (Verification Test 2)

[0065] The position of the nozzle 2 is fixed by the cavitation treatment device 1. The cavitation fluid C1 of 70 MPa supplied from the high-pressure water supply source (not shown) collides with the upper surface of the verification workpiece W (stainless steel round rod) fixed on the rotating shaft 4a. Thereafter, the cavitation fluid C2 collides with the side wall 3a and the bottom 3b of the direction switching part 3, and the cavitation fluid C4 collides with the lower surface of the workpiece W through the inner side of the direction switching part 3 for 5 minutes.

[0066] Figure 4B This is the test result of verification test 2. It was visually confirmed that concave-convex dents were formed on the surface of the workpiece W. The residual stress was measured using a commercially available residual stress measuring device, and as a result, a compressive stress of minus 550 MPa remained.

[0067] In the case of comparing Verification Test 1 and Verification Test 2, it was found that more and larger dents were formed on the surface in Verification Test 2, and the value of the compressive stress was a deeper value. Therefore, it was found that there was a difference between the primary cavitation effect on the upper surface of the workpiece W and the secondary cavitation effect on the lower surface of the workpiece W.

[0068] By continuously applying the primary cavitation effect to the upper surface of the workpiece W in Verification Test 1 for a long time, it takes a considerable amount of time to reach the level of the secondary cavitation effect on the lower surface of the workpiece W in Verification Test 2. In addition, if too much time is spent, the workpiece W itself may become brittle.

[0069] (Verification Test 3)

[0070] The tests were conducted by performing both the verification test 1 and the verification test 2. Specifically, the cavitation treatment device 1 was used to rotate the rotating shaft 4a and the workpiece W by driving the driving device 4. Then, the position of the nozzle 2 was fixed, and the 70MPa cavitation fluid C1 supplied from the high-pressure water supply source (not shown) collided with the upper surface of the verification workpiece W (stainless steel round bar) fixed on the rotating shaft 4a. After that, the cavitation fluid C4 collided with the side wall 3a and the bottom 3b of the direction switching portion 3, and collided with the lower surface of the workpiece W through the inner side of the direction switching portion 3 for 19 minutes.

[0071] Figure 4C This is the test result of verification test 3. It can be seen that the left surface of the workpiece W in verification test 1 is thinly peeled and there are both concave and convex dents on the surface of the workpiece W in verification test 2. The residual stress was measured using a commercially available residual stress measuring device, and the result showed that a negative compressive stress of 550 MPa remained.

[0072] According to verification test 3, it is possible to impart a primary cavitation effect (imparting residual stress on the surface) to the upper surface of the workpiece W and a secondary cavitation effect (imparting residual stress in the deep part) to the lower surface of the workpiece W in stages, making it possible to make the compressive stress residual in a shorter time than before without applying excessive load to the workpiece W.

[0073] As mentioned above, the present invention is not limited to the above-mentioned embodiment, and it is needless to say that the present invention can be appropriately modified within the scope not departing from the gist of the present invention.

Claims

1. A cavitation treatment device, characterized in that: have: a nozzle that sprays a cavitation fluid toward a workpiece; a direction switching portion that changes the flow direction of the cavitation fluid that has collided with the workpiece and branched off to surround the inner side of the direction switching portion; a drive device having a rotation shaft and causing the workpiece to rotate together with the rotation shaft; as well as A support portion supports one end of the rotating shaft.

2. The cavitation treatment device according to claim 1, characterized in that: The direction switching unit has: a side wall that changes a flow direction of the cavitation fluid that branches off after colliding with the workpiece; and A bottom portion changes the flow direction of the cavitation fluid that collides with the side wall and changes its flow direction.

3. The cavitation treatment device according to claim 1 or 2, characterized in that: The direction switching portion is concave in shape.

4. The cavitation treatment device according to any one of claims 1 to 3, characterized in that: The nozzle sprays the cavitation fluid toward a position eccentric from the center of the workpiece to cause the cavitation fluid to collide.

5. The cavitation treatment device according to any one of claims 1 to 4, characterized in that: The side wall has a height greater than a height at which the cavitation fluid collides with the workpiece.

6. The cavitation treatment device according to any one of claims 1 to 5, characterized in that: A distance between the workpiece and the side wall in a horizontal direction is less than half of a radius of the workpiece.

7. A cavitation treatment method, characterized in that: include: By ejecting the cavitation fluid from the nozzle and causing it to collide with the upper surface of the workpiece, the flow direction of the cavitation fluid is branched, By causing the branched cavitation fluid to collide with the side wall of the direction switching portion, the flow direction of the cavitation fluid is changed. The flow direction of the cavitation fluid is changed by causing the cavitation fluid having changed its flow direction at the side wall to collide with the bottom of the direction switching portion. The cavitation fluid having changed its flow direction at the bottom is caused to collide with the lower surface of the workpiece.

8. The cavitation treatment method according to claim 7, characterized in that: The workpiece is rotated by a drive device.

9. The cavitation treatment method according to claim 7 or 8, characterized in that: The cavitation fluid ejected from the nozzle is caused to collide with a position eccentric to the center of the workpiece.

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