Patent Application
20220203485
This application claims the benefit of priority to Japanese Patent Application No. 2020-219169, filed on Dec. 28, 2020, the entire contents of which are hereby incorporated by reference.
The present invention relates to an apparatus and a cavitation processing method for cavitation processing on a component surface.
Conventionally, a cavitation processing is performed to a high performance parts such as aircraft parts to add compressive residual stress on the surface of the various parts, or to form a dimple shape for retaining lubricating oil while alleviating friction. The cavitation processing is a generic term for surface treatment, peening, cleaning, peeling, cutting, deburring, etc.
The cavitation processing utilizing liquid (e.g., water) has often not been elucidated in principle. Thus, establishing a method or equipment for stably controlling cavitation is not easy.
For example, a system for processing an internal surface of a component is disclosed. The system includes a tank, fluid, a nozzle, and a deflection tool. The tank positions a component inside. The fluid in the tank submerges the component when the component is positioned in the tank. The nozzle is submerged in the fluid to generate a flow of cavitation fluid directed in a first direction. The deflection tool submerged in the fluid having a deflection surface that redirects the flow of cavitation fluid from the first direction to a second direction. The first direction is away from the inner surface of the component, and the second direction is directed to the inner surface of the component. (See, for example, Japanese Patent Application Laid-Open No. 2020-157470, hereinafter referred to as “Patent Literature 1”).
As disclosed in Patent Literature 1, changing the flow direction of the cavitating fluid by using the deflection tool enables cavitation process inside the workpiece having a complex shape. However, there is room for improvement in order to certainly give cavitation to the target position of the workpiece to be cavitated.
For example, when the cavitation fluid is directly collided with the workpiece, or merely collided with the workpiece by changing the flow direction of the cavitation fluid, the cavitation processing around the target position of the workpiece, rather than the exact target position, may be caused.
The cavitation fluid ejected from the nozzle in the liquid contains cavitation bubbles. It is known that the cavitation bubbles temporarily stay in the liquid. Even if the cavitation fluid collides with the workpiece in a state where cavitation bubbles are dispersed, the cavitation effect (residual stress, etc.) is not properly given to the target position of the workpiece. That is, even if the cavitation fluid collides with the workpiece in a state where cavitation bubbles are dispersed, giving cavitation effect properly to the target position of the workpiece requires increased number of processing, and thus takes a long time.
An object of the present invention is to provide a cavitation processing apparatus and a cavitation processing method that give cavitation effect (residual stress, etc.) properly at desired processing position.
A cavitation processing apparatus according to the present invention includes:
a nozzle configured to eject cavitation fluid;
a direction changing member configured to change a flow direction of the cavitation fluid, the direction changing member having groove for guiding the flow direction of the cavitation fluid, the groove configured to suppress cavitation bubbles contained in the cavitation fluid from dispersing; and
a workpiece fixing member on which a workpiece is arranged.
A cavitation processing method according to the present invention includes:
ejecting cavitation fluid from a nozzle;
guiding a flow direction of the cavitation fluid ejected from the nozzle while suppressing cavitation bubbles contained in the cavitation fluid from dispersing in a groove; and causing the cavitation bubbles guided by the groove to collide with a workpiece.
According to the cavitation processing apparatus and the cavitation processing method of the present invention, the cavitation effect (residual stress, etc.) is properly given to a desired position.
Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
A cavitation processing apparatus 1 of the present embodiment performs cavitation processing to a surface of high performance parts used in nuclear power field, or to the surface of the general metal parts or the like. As shown in
The nozzle 2 ejects the cavitation fluid C1 supplied from the high-pressure fluid supply source (not shown).
The cavitation fluid C1 ejected from the nozzle 2 collides with the surface of the direction changing member 3 to change the flow direction of the cavitation fluid C1. The direction changing member 3 primarily receives the flow of the cavitation fluid C1. The surface of the direction changing member 3 is thus preferably high strength material for avoiding erodes or damage by cavitation.
The grooves 5 have shape to guide the flow direction of the cavitation fluid C1 to suppress the dispersion of cavitation bubbles C2 constituting the cavitation fluid C1.
As shown in
The grooves 5 have preferably uneven shape. This allows the cavitation bubbles C2 to enter the concave portion to suppress the cavitation bubbles C2 from dispersing, which improves the cavitation effect (residual stress, etc.). Furthermore, as the cavitation bubbles C2 are less likely to disperse, the workpiece W can be performed cavitation processing in a shorter time than before.
The shape, width, depth, number, etc. of the grooves 5 are not limited. The grooves 5 may have any shape that functions as a flow path of the cavitation fluid C1. For example, the grooves 5 may have a triangular shape shown in
The groove 5 is a flow path for guiding the cavitation fluid C1 to the workpiece W. In the case of a linear flow path, the cavitation fluid C1 directly collides with the workpiece W.
When the groove 5 has a single groove or arc shaped groove, the groove 5 having a relatively wide groove width allows the cavitation fluid C1 as a single flow to collide with the workpiece W, which results in locally higher cavitation effect.
Specifically, as shown in
The grooves 5 having a plurality of concave grooves or arc shaped grooves in parallel allows the cavitation fluid C1 as a plurality of flows to collide with the workpiece W, which results in higher cavitation effect for wide width.
Specifically, as shown in
When a plurality of flow paths of linear shape are merged at a position close to the workpiece W, the width of the cavitation process for the workpiece W is narrowed, while higher cavitation effect is obtained as the amount of cavitation bubbles C2 is increased.
The groove 5 is a flow path for guiding the cavitation fluid C1 to the workpiece W. In order to more easily guide the cavitation fluid C1, it is preferable to tilt the nozzle 2. The tilt angle of nozzle 2 is adjusted in the range of 0 to 180 degrees. Tilting the nozzle 2 suppresses the cavitation effect to be imparted to the groove 5.
In addition to the tilting the nozzle 2, as shown in
As shown in
The workpiece fixing member 6 fixes the workpiece W. For example, the workpiece fixing member 6 fixes the end portion of the workpiece W by fasteners such as a plurality of bolts, or fixes the workpiece W by sandwiching a portion of the workpiece W.
The angle adjusting unit 7 adjusts a tilt angle of the workpiece W. The angle adjusting unit 7 is connected to the workpiece fixing member 6. For example, the angle adjusting unit 7 is connected to a lower portion of the workpiece fixing member 6. The angle adjusting unit 7 performs positioning at an angle of 0 to 180 degrees, more preferably, 45 to 135 degrees, by adjusting an angle adjusting unit switch 7a. The angle adjusting unit 7 has a specific internal structure such as a sliding mechanism or a cylinder mechanism. The angle adjusting unit switch 7a may be either manual or automatic.
A lifting unit 9 may be disposed below the direction changing member 3. Adjusting a lifting unit adjusting switch 9a allows a lifting support portion 9b to expand or contract for the lifting unit 9 to adjust the height of the direction changing member 3. Specifically, the lifting unit 9 has a sliding mechanism or a cylinder mechanism. The lifting unit 9 adjusts the height of the direction changing member 3 according to the processing conditions of the cavitation. The lifting unit 9 allows the cavitation bubble C2 to collide with the target position of the workpiece W in the vertical direction to perform cavitation processing.
A second direction changing member 4 may be further provided for the flow direction of the cavitation fluid C1 changed by the direction changing member 3 to be further changed. For example, the second direction changing member 4 is fixed to the workpiece fixing member 6. The second direction changing member 4 may have a groove similarly to the direction changing member 3. In that case, the groove of the second direction changing member 4 may change the flow direction of the cavitation fluid C1 in the plane.
Adjusting the flow direction of the cavitation fluid C1 in two stages of the direction changing member 3 and the second direction changing member 4 properly adjusts the speed of the cavitation fluid C1. Further, this allows the cavitation processing for the workpiece W having a complex configuration, and to increase variations such as adjustment of the target position of the workpiece W and the collision force.
A control device 12 may be provided that can adjust the amount of cavitation bubble C2. For example, the cavitation bubble C2 is affected by a temperature change in the liquid. The control device 12 is, for example, a commercially available temperature regulating device. The proper temperature is 40 to 50° C. The control device 12 adjusts the temperature in accordance with the cavitation effect determined for the environment and the workpiece in the liquid.
As shown in
The rotation shaft of the rotation mechanism 10 may be configured to adjust a position with respect to the workpiece fixing member 6 or the workpiece W. For example, the rotation shaft of the rotation mechanism 10 arranged at the upstream of the workpiece fixing member 6 (toward direction changing portion 3) allows the cavitation fluid C1 having the flow direction guided in the groove 5 to collide with the workpiece W at a short distance. Further, the rotation shaft of the rotation mechanism 10 arranged at the downstream of the workpiece fixing member 6 (away from the direction changing member 3) allows the cavitation fluid C1 having the flow direction guided in the groove 5 to collide with the workpiece W at a long distance. The position of the rotation shaft of the rotation mechanism 10 may be appropriately selected by the relationship between the distance of the direction changing member 3 and the groove 5 from the nozzle 2.
Next, the cavitation processing step of the present embodiment will be described.
First, fixing operation of the workpiece W is performed, and the cavitation processing conditions are adjusted. The length and height of the direction changing member 3 are firstly adjusted by the collision distance adjusting unit 8 and the lifting unit 9 to fix the workpiece W to the workpiece fixing member 6. Next, the angle of the angle adjusting unit 7 is properly set and fixed to 0 to 180 degrees, more preferably 45 to 135 degrees.
Before or after the fixing operation, the tank T is filled with liquid such as water. Performing the cavitation process in the liquid leads to enclosing the cavitation bubbles C2 (aggregate) stably in groove 5. This allows the appropriate amount of cavitation bubble C2 to collide with the workpiece W for obtaining the appropriate cavitation effect.
Next, the high-pressure water supply source (not shown) is activated with the position of the nozzle 2 fixed to eject the cavitation fluid C1 from the nozzle 2 to the direction changing member 3. The ejected cavitation fluid C1 collides with the groove 5 of the direction changing member 3 to be decelerated. The cavitation fluid C1 entering the recess of the groove 5 advances toward and collides with the workpiece W to perform the cavitation processing.
The decelerated cavitation fluid C1 having a high concentration of cavitation bubbles C2 collides with the workpiece W. This suppresses the cavitation processing to be performed to the undesired portion due to high speed of the cavitation fluid C1. This also allows the cavitation processing to be performed to the target position of the workpiece W.
First, fixing operation of the workpiece W is performed, and cavitation processing conditions are adjusted. As shown in
Next, the high-pressure water supply source (not shown) is activated with the position of the nozzle 2 fixed to eject the cavitation fluid C1 from the nozzle 2 to the direction changing member 3. The ejected cavitation fluid C1 collides with the groove 5 of the direction changing member 3 to be decelerated. The cavitation fluid C1 entering the recess of the groove 5 advances toward and collides with the second direction changing member 4 to be further decelerated. The cavitation fluid C1 advances toward and collides with the workpiece W along the surface of the second direction changing member 4 to perform the cavitation processing.
The decelerated cavitation fluid C1 having a high concentration of cavitation bubbles (aggregate) collides with the workpiece W. This suppresses the cavitation processing to be performed to the undesired portion due to high speed of the cavitation fluid C1. This also allows the cavitation processing to be performed to the target position of the workpiece W.
Next, a verification test of the cavitation effect when utilizing the cavitation processing apparatus 1 of the embodiment will be described.
Two types of tests were performed: a test in which the cavitation processing apparatus 1 was not used (Comparative Example 1) and a test in which the cavitation processing apparatus 1 was used (Working Example 1).
In Comparative Example 1, without utilizing the cavitation processing apparatus 1, the cavitation fluid C1 of 40 MPa supplied from the high-pressure water supply source (not shown) was directly collided with a verification workpiece W (aluminum plate) for 15 seconds from the nozzle (the same as the nozzle 2 of the present embodiment).
In Working Example 1, using the cavitation processing apparatus 1, the position of the nozzle 2 is fixed, and the cavitation fluid C1 of 40 MPa supplied from the high-pressure water supply source (not shown) was ejected toward the direction changing member 3 from the nozzle 2. The cavitation fluid C1 flowed through the groove 5 of the direction changing member 3 to collide with the verification workpiece W for 15 seconds.
The first verification test 1 only judges the effect on the apparent surface. In the second verification test, residual stress applied to each of the workpiece W in Comparative Example 1 and Working Example 1 was measured by using a commercially available residual stress measuring apparatus.
From the results of the verification test 1 and the verification test 2, a larger cavitation effect is obtained in Working Example 1.
As described above, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified without departing from the gist thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-219169 | Dec 2020 | JP | national |
