JP3320105B2 - Nozzle for cavitation jet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for modifying the surface of a metal material, and irradiates a surface of a metal material with a water jet at a subsonic speed (transonic speed, subsonic speed or lower) in water. In this method, the surface of a metallic material in which a tensile stress remains due to the collapse pressure of the cavitation bubbles generated in the process is treated so that a compressive stress acts.

[0002]

2. Description of the Related Art The residual stress of an existing structural material is subjected to peening treatment using a shot blast in which steel balls are blown by an air current, a sand blast using sand grains, a cryo blast using ice grains, and the stress is reduced in a tensile direction ( From the direction of crack propagation) to the compression direction. Such a peening technique is widely used at the time of processing various mechanical structures or parts as a measure against residual stress.

[0003] However, there are many structures which must be peened by all means even in such an environment where blasting cannot be performed. For example, the nozzle portion and the offshore structure of an aged reactor pressure vessel are both in water, and it is almost physically or economically impossible to remove and treat the water. In a reactor pressure vessel, a large amount of radioactivity is released when water is drained. Recovering the blast particles is also a difficult task. If ice particles are used, collection is unnecessary,
Economic merits are unlikely.

[0004] The use of high-speed water jets is widely known as a unique processing, mining or cleaning technique.
Attempts to utilize this for surface stress modification have been made by Westinghouse (JP-A-62-63614). Peening with a water jet also has the advantage of preventing the local temperature rise due to the effect of water cooling. However, this is an operation in the atmosphere in which the axial dynamic pressure of a water jet can be effectively used, and there is no guarantee that this technology can be directly applied as a peening technology using a submerged water jet.

FIG. 48 shows the structure of a gas-phase water jet nozzle and a jet.

In the drawing, reference numeral 1310 denotes an aerial water nozzle main body, 1311 denotes high-pressure supply water, 1312 denotes a nozzle central axis,
Reference numeral 1313 denotes a contraction portion, 1314 denotes an ejection hole, 1315 denotes a continuous liquid flow (core portion), 1316 denotes a droplet flow, and 1317 denotes an aerial water jet.

[0007] As shown in FIG. 49, the decay of the jet axial dynamic pressure is considerably rapid in water. This is because the diffusion is fast because it is in phase with the resistance of the surrounding water. In order to obtain an axial pressure equivalent to that of a gas-phase water jet in water, an ultra-high pressure generator is required, resulting in a very disadvantageous technique in terms of cost.

On the other hand, in the underwater water jet, cavitation is generated by a shearing action between the jet and the surrounding water. If the cavitation can be controlled well and the generated bubbles can be used effectively, there is a possibility that the effect equivalent to the gaseous water jet can be realized at a low injection pressure.

[0009]

FIG. 47 shows that:
It is a typical structure of a nozzle used for water jet processing. The purpose of this nozzle is to squeeze a water stream into a beam in the gas phase, and even when used as a submerged water jet, cavitation hardly occurs. The reason is that the squeezing angle θ of the contraction portion 1305 is small, and the depressurizing action here is too gentle.

In addition, the outer surface of the water jet has little turbulence, and it is difficult to generate cavitation due to shear vortices. That's why.

In the drawing, 1301 is a submerged water jet nozzle main body, 1302 is high-pressure supply water, 1303 is a parallel portion of water supply, 1304 is a nozzle center axis, 1306 is a jet hole,
307 is a submerged water jet, 1308 is a solid surface of a processing object,
Reference numeral 1309 denotes ambient water around the object to be processed.

The prior art shown in FIG.
No. 8554) is a nozzle developed for various operations in water, and the use of cavitation is declared.

In the drawing, 1401 is a nozzle body,
1402 is an orifice, 1403 is a conical opening, 14
04 is a conical hollow part, 1405 is a piping member, 1406 is a high-pressure jetting device, and 1407 is an object to be jet-processed.

The prior art shown in FIG. 51 (JP-A-61-81)
No. 84) attempts to remove attached contaminants by the action of cavitation generated in a submerged water jet.

In the figure, reference numeral 1501 denotes a water tank;
2 is a part to be cleaned, 1503 is a nozzle, 1503a is nozzle cleaning, 1503b is a jet hole, 1504 is water, 1505
Is a pipeline.

In these examples, there is a limit in terms of the structure of the nozzle even if the cavitation is actively generated. In order to promote cavitation, it is necessary to devise a strong turbulence in the water flow in the nozzle or to forcibly supply cavitation bubble nuclei.

FIGS. 52 to 54 show three examples of the structure of the self-resonant cavity phenomenon promoting nozzle. In this nozzle, the self-resonance phenomenon is generated by the cavity provided in the nozzle, and the cutting efficiency is enhanced by utilizing the cavity generated in the gaseous water jet. The problem with this nozzle is
Since the cavitation occurs in the nozzle, the nozzle is in a bubble-locked state (actually, the bubble-locked state and the phenomenon that only bubble-free water is jetted are repeated in accordance with the resonance frequency), causing an increase in pressure loss and an increase in water flow. Violently pulsates (oscillations in the cavity feed back to the upstream side and become a state of self-excited oscillation).

In these figures, 1601 is water,
Reference numeral 1602 denotes a nozzle main body, and 1603 denotes a resonance cavity.

Further, as shown in FIG.
A conventional nozzle intended to squeeze a water jet into a beam in order to process various materials in the atmosphere has a collision pressure portion generated on a collision surface as shown in FIG. Is extremely local, so peening efficiency cannot be said to be high, for example, a long time is required for construction.

In FIG. 55, 1701 is a high-pressure water injection nozzle, 1702 is high-pressure water, 1703 is a gas-phase in-water jet, 1704 is an object to be processed, 1705 is a pressure distribution,
706 is a central axis.

That is, as shown in FIGS. 57 (a) and 57 (b), the peening pressure generating portion 1909 has a trajectory 1901 in order to peening the entire area where the peening is required 1901.
The nozzle must be moved vigorously so that it looks like 5. The structure of the tip of the manipulator for mounting the nozzle will also be complicated.

When water is jetted from a conventional nozzle as shown in FIG. 50 underwater, that is, in the case of a submerged water jet, the dynamic pressure on the jet shaft attenuates very rapidly in water. FIG. 49 shows a comparison with the characteristics in the gas phase. On the other hand, in such a submerged water jet 1803, a spiral cavity 1804 due to a shear type vortex is generated on the outer periphery of the jet. FIG. 56 schematically shows such a situation. In the case of the conventional nozzle, the turbulence due to the vortex is weak, the generation of the cavitation is insufficient / unstable, and the pressure distribution 1806 caused by the collapse of the cavitation bubble is small. Around the central axis 1807.

In the figure, reference numeral 1801 denotes a water injection nozzle, 1802 denotes high-pressure water, and 1805 denotes an object to be pressurized.

As described above, the on-axis dynamic pressure of the jet is low in the water, and the pressure distribution inevitably becomes "dropout". If the generation of the cavitation bubbles is remarkably active, the bubbles on the outer periphery are entrained into the center of the jet (entrance), but the entrainment work cannot be expected with the unstable cavitation as shown in FIG. As shown in FIGS. 57 (c) and (d), the required peening location 1
In order to apply the 903 evenly, the nozzle must be traversed in a complicated manner. (A) and (c) show examples of moving the nozzle in a pendulum shape, and (b) and (d) show examples of reciprocating the nozzle.

Reference numerals 1902 and 1904 denote portions requiring peening, reference numerals 1906 to 1908 denote movement locus of the nozzle, and reference numeral 191.
0 is a peening pressure generating portion.

In the prior art shown in FIG.
An air suction pipe 2002 that uses a suction action by accelerating a water flow is provided, and outside air is sucked into high-pressure water 2004 and mixed therewith to create a two-phase jet 2005 in a gas phase containing bubbles. In this case, it is advantageous if the sucked air bubbles act as a cavitation, but if it acts as a 'cushion'-like cushioning effect, it has an adverse effect on peening. If the peening location is deep underwater, a long air suction pipe is not practical.

Reference numeral 2001 denotes an annular nozzle body;
3 is air.

An object of the present invention is to provide a nozzle for jetting cavitation, which has less adverse effects due to generation of cavitation.

[0029]

[Means for Solving the Problems]

1. In the present invention, in surface stress reforming (peening) using a water jet in water, a strong turbulence or a high-frequency turbulence having a bubble nucleus exciting action is imparted to a submerged water jet ejected from an orifice. Thus, it is intended that the cavitation be actively performed.

(1) The jet hole is a coaxial double tube type, and strong turbulence is created inside the jet water flow, which disrupts the jet structure.

(2) High-pressure water supplied from two directions is merged in the ejection hole to forcibly accelerate the water flow in the ejection hole.

(3) A flat, fan-shaped underwater jet is used to increase the shear area with the surrounding water and promote cavitation due to strong turbulence.

(4) Ultrasonic waves that can become bubble nuclei are applied to the high-pressure water supply flow path to activate the cavitation actively. Ultrasound has the function of causing defects in the molecular structure of water. This results in homogeneous nucleation and significant formation of cavitation bubbles.

2. In the present invention, the following measures are taken.

One or a plurality of annular groove-shaped cavity vibrators having a rectangular cross section are engraved around the inner wall of a jet hole for jetting high-pressure water into water. This cavitator can be replaced with a blade type for producing an adhesion type cavity in addition to the annular groove type, and this may be provided at the outlet of the ejection hole.

On the other hand, in order to effectively utilize the nuclear supply function of these cavitators, a sleeve-type outer ring is provided at the outlet of the ejection hole so as to protrude into the surrounding water, and the vortex generated in the ring acts on the outer ring. Excites bubble nuclei to develop cavitation.

3. According to the present invention, a nozzle for ejecting water in water has a structure in which the respective central axes of a conduit portion, a contraction portion, and an ejection hole on the upstream side of the nozzle body are inclined or eccentric, or a combination of both. In this way, strong turbulence occurs in the depressurized flow portion in the nozzle that is not in the conventional straight type nozzle (in the conventional type nozzle, the central axes of the conduit portion, the contraction portion, and the ejection hole are aligned in a straight line). Or cavitation bubbles are generated, and the cavitation of the submerged water jet spouted from the nozzle is remarkably promoted. By the way, in order to cause the same active cavitation as when using the nozzle according to the present invention, it is necessary to use a considerably high pressure (3000 kg) in the case of the conventional nozzle.
f / cm ² or more).

[0038]

[Action]

1. The cavitation bubbles generated by the submerged water jet collapse on the surface of the object to be processed or very near the surface to generate impact pressure. With this pressing force, the structural material is modified so that the residual tensile stress is on the compression side. The collapse of the cavitation pressure is promoted by the collision of the high-speed water stream with the surface of the workpiece, and the water pressure action caused by the collision of the high-speed water stream itself is also effective in modifying the surface stress of the structural material.

In short, the present invention seeks to make good use of the synergistic effect of the collision pressure of a high-speed water jet in water and the impact pressure generated when the cavitation bubbles collapse.

2. First, a cavity bubble nucleus is stably supplied in an annular groove-shaped cavity vibrator engraved in an ejection hole. Further, the vortex originating from the shear layer formed in the sleeve-shaped outer peripheral ring which projects into the surrounding water at the outlet of the blast hole is stably formed by the blast water flow, and the cavitation bubbles generated by the cavitator are introduced into the vortex flow. Is supplied so as to flow.
Due to the strong pressure fluctuations generated in the vortex and the presence of bubbles supplied from the cavitator, the bubble nuclei in the water are excited in a chain, and the cavitation develops. The bubbles generated in the vicinity of the nozzle outlet in this manner are dispersed (diffused) throughout the inside of the jet by the flow generated by the jet entraining the surrounding water. The result is a jet with developed cavitation from the nozzle.

3. The cavitation bubbles generated by the submerged water jet collapse on the surface of the object to be processed or very near the surface to generate impact pressure. By this pressure, the tensile residual stress of the structural material is modified so as to be on the compression side. The collapse of the cavitation pressure is promoted by the collision of the high-speed water stream with the surface of the workpiece, and the water pressure action caused by the collision of the high-speed water stream itself is also effective in modifying the surface stress of the structural material.

In short, the present invention seeks to make good use of the synergistic effect of the collision pressure of a high-speed water jet in water and the impact pressure generated when a cavity bubble collapses.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An underwater peening nozzle embodying the present invention generates a continuously active cavitation in a submerged water jet spouted from the nozzle by forcibly imparting strong turbulence to the water stream at the nozzle portion. It is based on the intent to say.

(Embodiment 1) FIG. 1 shows the structure of a coaxial injection nozzle in which water streams of different speeds are jetted and mixed coaxially with a water stream in an ejection hole to produce severe turbulence in the water stream in the nozzle. FIG.

In the nozzle body 101, the mainstream high-pressure water 104
Is guided through the main flow water conduit 102, and is jetted from the (Dj1) outlet 103 having a smaller diameter than the main flow water conduit 102 toward the underwater workpiece at a speed Uj1. The on-axis injected high-pressure water 108 passes through the on-axis injected water flow conduit 106 into the on-axis injected water flow nozzle 106 (diameter Dj) such that the outlet of the outlet is located at a position inserted by a length l ₁ into the outlet 103.
From 2), it is injected coaxially into the ejection hole 103 at the speed Uj2. The relationship between the diameter Dj1 of the ejection hole 103 and the diameter Dj2 of the on-axis injection water flow nozzle 107 is Dj2 = (1/3 to 1/6) Dj1 (1).

Also, Uj1 and Uj2 may be equal, but it is more effective to satisfy Uj2> Uj1. The water flows of both are set such that Uj2 = (1.5 to 4.0) Uj1 (2) Set the injection pressure.

As described above, mixing another flow with the flow in the orifice immediately before the jetting causes a much more intense transient turbulence than expected from the apparent Reynolds number, and The jet is also severely disturbed from the inside.

Accordingly, in a submerged water jet, a well-developed cavitation is continuously and stably generated. When there is no coaxial on-axis injection water 108, cavitation bubbles are generated in the contraction pressure reducing section near the inlet of the outlet 103, but the pressure is recovered near the outlet of the outlet and the bubbles disappear. There is. The axial injection water 108 also has the effect of forcibly pushing out such cavitation bubbles before they disappear. 105 is a central axis.

FIG. 2 shows an outline of the water supply system of this embodiment. Water is supplied from the two water supply units, the mainstream water supply unit 110 and the axial injection water supply unit 112, at respective predetermined injection pressures.

According to the present invention, since the peening effect is sufficiently exhibited even at a relatively low injection pressure, an ultra-high pressure pump is not required, and even if two injection units are used, the cost is not significantly increased. When one injection unit is used,
A pressure regulating valve is provided in the conduit to branch off as mainstream water and axial injection water.

In the drawing, reference numeral 109 denotes an object to be processed, 111 denotes a remote conduit for mainstream water, 113 denotes a remote conduit for axial injection water, and f denotes a jet.

(Embodiment 2) This example is a nozzle for artificially applying high-frequency vibration to water guided to the nozzle at high pressure.

FIG. 5 shows the structure of the nozzle, and FIG. 7 shows a schematic system of water supply. The high-pressure water 511 is supplied to the nozzle body 50.
1 is supplied from a high-pressure water conduit 502 opening to the upstream side of
Through the nozzle contraction part 513 whose diameter contracts,
Is sprayed toward the workpiece 509. A sound horn 505 is provided on the side surface of the high-pressure water conduit 502, and vibration of several KHz to several hundred KHz is directly applied to the high-pressure water. The sound horn is supplied with a signal from an oscillator 508 via an amplifier (amplifier) 507. Although the sonic horn generates heat, it is not necessary to cool the horn because the portion where the temperature tends to rise most is forcibly removed by the water flow.

Theoretically, defective vacancies in water are excited only by the frequency, or impurities (dissolved gas, dirt, ions, etc.) are excited in the same manner, and cavitation bubbles are generated. The growth of bubbles generated in this way is
The propagation of the pressure wave triggers the bubble nuclei to be excited simultaneously in a chain, and a large amount of cavitation bubbles is generated.

In the figure, 503 is a high-pressure water supply unit, 504 is a high-pressure water remote conduit, 506 is a lead wire,
Reference numeral 10 denotes water, 512 denotes a nozzle center axis, 515 denotes an enlarged orifice portion, and 516 denotes a seal ring.

(Embodiment 3) This embodiment corresponds to Embodiment-1.
It is similar to 8 and 10 show the structure of the nozzle portion and the supply system of high-pressure water, respectively. The purpose of this nozzle is to cause the water flow in the nozzle orifice to be jet-mixed from another orifice opened on the side wall surface of the nozzle, thereby creating severe turbulence in the water flow in the nozzle.

The mainstream high-pressure water 604 is supplied from a mainstream water conduit 602 opened to the upstream side of the nozzle body 601.
Long (compared to Example-1) ejection hole 603 (diameter Dj)
It is jetted at a speed Uj. On the side wall of the ejection hole 603,
The side injection water jet hole 609 is opened (diameter Dsj) at an inclination angle (confluence angle) of θm, and the side injection high-pressure water 610 is jetted at a flow rate Usj into the water flow in the jet hole 603.

The diameter Dj of the ejection hole 603 and the diameter Dsj of the side injection water ejection hole 609 are set so as to satisfy the following relationship.

Dsj = (1 / 1.5 to ４) Dj (3) Further, regarding the jet flow velocities Uj and Usj, it is assumed that Usj = (1.2 to 3.0) Uj (4).

As compared with the first embodiment, Usj for Uj
The reason for making the magnification slightly smaller is that the direction of jetting of the laterally injected high-pressure water is inclined by the merging angle θm, so that the mixing is performed more quickly than in the case of Example-1. Example-
If Usj / Uj is increased to a value equal to 1, the pressure loss becomes too large. Therefore, the side injection water supply unit 6
Therefore, the pump capacity of the thirteenth pump must be increased, which may increase the cost. It is preferable that the merging angle θm is 30 ° <θm <60 ° (5).

In the figure, reference numeral 605 denotes a central axis, and reference numeral 606 denotes
Is a side injection water flow conduit, 607 is a side injection water contraction tube, 60
8 is a side injection water shaft, 611 is a mainstream water supply unit, 61
2 is a mainstream water remote conduit, 613 is a side injection water supply unit, 614 is a side injection water remote conduit, 615 is an object to be processed, 616 is water, and g is a jet.

(Embodiment 4) This embodiment is a nozzle in which a circular ejection hole is suddenly changed in shape at the outlet thereof into a broken shape, and a flat-type cavity is ejected from the crack. FIGS. 11, 12, and 13 show the nozzle structure. 14 and 15 show a fan-shaped submerged water jet, and FIG. 16 shows a water injection supply system.

The high-pressure water 907 is supplied from a high-pressure water conduit 902 that opens to the upstream side of the fan nozzle (the so-called underwater water jet has a flattened and fan-like shape, and thus is referred to as a fan). The fuel is accelerated by the nozzle contracting portion 909, and is jetted from the crack-shaped nozzle opening 911 as a fan-shaped cavitation jet h toward the workpiece 903 through the nozzle detail 910 having a circular cross section.

In general, cavitation is likely to occur when the vortex is cut off in the vortex portion of the shear layer around the underwater jet. When a fan-shaped jet structure is used as in this embodiment, the so-called "outer surface" of the jet is increased as compared with a substantially conical normal jet, so that the shear vortex becomes more active and the generation of cavitation bubbles is also significantly amplified. Will be done. Further, when the cavitation is generated on the outer circumference, the jet flow is flat, and the turbulence due to the cavitation is likely to propagate to the inside of the jet. As a result, the entire submerged water jet is composed of intense cavitation bubbles.

This nozzle can be said to be suitable when a relatively large steel material is to be subjected to surface stress reforming by one jet irradiation.

In the figure, reference numeral 904 denotes a high-pressure water remote conduit, 905 denotes a high-pressure water supply unit, 906 denotes water, 908
Is a central axis of the nozzle, 912 is a fan-shaped underwater jet, and 913 is a location where a spiral cavitation is generated.

Next, the mutual relationship between the components will be described.

(Embodiment 1) FIGS. 3 and 4 schematically show the phenomena under both conditions when there is no axial injection water (α) and when it is provided (β).

When there is no axial injection water, the pressure is rapidly reduced at the point where the water flow contracts (a), and cavitation bubbles are generated (b). However, when the contracted water flow re-adheres to the side wall surface of the ejection hole 103, the pressure is recovered, and the cavitation bubbles disappear (c). Therefore, in the case of the structure without measures such as (α), generation of active cavitation bubbles from inside the water jet cannot be expected. It is only the cavitation caused by the vortex generated in the shear layer around the underwater jet, and it is difficult to increase the peening efficiency.

In the embodiment of the present invention, the high pressure water
By the action of 08, the cavitation bubbles (b) are forcibly ejected into the underwater jet (d) (e). This creates a submerged water jet (f) that is severely disturbed by the cavitation bubbles from inside,
At or near the surface of the workpiece 109,
A large number of bubbles collapse (g), and the action of these pressure waves changes the tensile stress remaining on the steel surface to the compression side.

(Embodiment 2) FIG. 6 schematically shows a phenomenon in the nozzle. The pressure wave applied by the acoustic horn 505 propagates in the liquid (500a) and excites the bubble nucleus (500b). The bubble nuclei are in the nozzle contraction section 5
13 or generated in the process of being depressurized in the vent 514
It grows (500c), and the inside of the ejection hole 514 becomes a developed cavitation flow (500d). Therefore, the underwater water jet spouted from the spout hole becomes a stable cavitation jet (500e), so that the steel material surface can be efficiently peened.

(Embodiment 3) FIG. 9 is a schematic diagram showing a phenomenon in a nozzle. At a place where the two high-pressure waters merge obliquely, a partially mixed and mixed part 600a is formed with separation. Such a deviation in the flow in the ejection hole 603 triggers the water jet to be violently disturbed from the inside, and the underwater water jet after the ejection has cavitation caused by the disorder of the structure inside the jet. Generates violently.

On the other hand, a vortex-type cavity caused by the vortex is generated in the shear portion outside the underwater jet (600).
b). The synergistic effect of the two types of cavitation with different generation mechanisms provides a stable cavitation jet, which allows for highly efficient peening. 600c is a cavitation caused by structural disturbance inside the jet.

Embodiment 4 As shown in FIGS. 14 and 15, the fan-shaped underwater jet 912 has
More spiral cavitations 913 are generated than in a normal substantially conical jet. This is attributable to the shape of the jet, in which the “outer surface” increases. The development of the spiral cavitation 913 also promotes the development of the cavitation inside the jet, but the flat jet structure is suitable for the development of such a chain-like cavitation. Since the flat jet cavitation according to the present invention is sufficiently developed, the peening efficiency can be improved.

FIG. 17 shows an example of the results of a verification test in which the stress in the tensile direction remaining on the inner wall surface of the tube was modified in the compressive direction. Although the conventional nozzle as shown in FIG. 50 can improve the residual stress to some extent, the coaxial water mixing type nozzle (FIG. 1) embodying the present invention can reduce the stress to the compression side to a considerable level. You can see that it was quality. All of the methods for accelerating the cavitation of a submerged water jet according to the present invention produce a predetermined peening effect at a relatively low pressure and a low jet flow velocity. Therefore, the capacity of the water injection pump can be reduced. In addition, the cost of peening can be reduced if the viewpoint is changed, for example, because special consideration for piping and the like is not required.

The application of the present invention utilizing the high-speed jet in water is not limited to the steel material of the reactor pressure vessel described in the embodiment. Generally, in the modification of the surface stress, treatment at normal temperature without applying heat, that is, without transformation of the metal structure is much more preferable. The present invention is also advantageous from this point, and can be applied to surface stress modification of a pressure-resistant member of a boiler (thermal power). Considering that the work is underwater, the present invention can be applied to marine structures and ships in seawater.

Shells, algae and other small creatures adhere to the bottom of the ship below the sea surface, causing considerable flow resistance to running. In the present invention, these adherents are removed in sea water. To be able to If the removal of attached organisms becomes possible in seawater in this way, (1) the ship is docked, (2) the seawater is pumped out of the dock, (3) the wastewater mixed with attached matter is discarded, and (4) ) Fill the dock again with seawater.

A series of operations described above is omitted altogether, and the maintenance of the ship is performed more economically. It is preferable from the viewpoint of marine environment protection if the amount of the special paint used for removing the deposits is also reduced.

(Embodiment 5) FIG. 18 shows the structure of a nozzle according to Embodiment 5 as a vertical cross-sectional view passing through the center axis 8. A high-pressure water supply channel 3 to which the high-pressure supply water 2 is supplied, a contraction section 9 for reducing the pressure and accelerating the high-pressure supply water 2 by contracting the diameter, and a jetting hole 5 for injecting water into the water are provided along a central axis 8. A nozzle body 1 having a connection opening, a sleeve-shaped outer peripheral ring 7 provided so as to protrude from the nozzle body 1 into the surrounding water, and the nozzle main body 1 and the outer peripheral ring 7
And three components of a lock nut 6 for connecting the two.

On the inner wall of the ejection hole 5, a groove-shaped cavity 4, which is a gas-liquid supply section having a rectangular cross section and is an annular groove-shaped cavity, is provided. From this cavitator,
As will be described in detail later, the cavitation bubbles are stably supplied. Groove bottom diameter dc of the channel cavity 4, the diameter dn of ejection holes 5, d _C = (1.2~1.6) relationship d _n ... (6) is a range in dimensioned to hold. Further, the width l _C of the grooved cavity 4 and the length l _n of the ejection hole 5 are set so as to satisfy the following range.

L _C = (0.15−0.40) l _n (7) The dimensions of the cavitator as described above are suitable for stable supply of the cavitating bubbles. If the cavitator is too large, the bubbles will disappear after large bubbles are released, and if the cavitator is too small, the bubbles will not release. On the other hand, the spout hole outer peripheral ring 7 has a role of creating a strong vortex between the water jet spouted into the water and the surrounding water, and amplifying the cavitation. The inner diameter d _R of the ejection hole outer ring 7 is
It is designed to be 2 to 4 times the diameter of the ejection hole 5.

That is, d _R = (2-4) d _n (8) The length l _R of the outer peripheral ring 7 of the ejection hole is set to be slightly larger than the length of the ejection hole as in the following equation.

[0083] _{l R = (1.2~2.5) l n} ... (9) ( Example -6) 19, longitudinal section through the central axis 28 of the structure of the water nozzle according to Embodiment -6 It is shown as a diagram. The configuration of this underwater nozzle is basically the same as that of Example-5. It comprises a nozzle body 21, a ceramic member 30 having an opening of the ejection hole 25, an ejection hole outer ring 27 also serving to mount the ceramic member 30, and a lock nut 26 connecting the nozzle body 21 and the ejection hole outer ring 27. The reason for using ceramics for the member engraved with the cavitator is to minimize wear.

On the inner wall of the ejection hole 25, three groove-type cavities (cavitators) 24-1 to 24-3 whose diameters and widths gradually increase toward the downstream side are engraved. From these cavitator rows, cavitation bubbles are continuously supplied. The nozzle according to this embodiment is suitable for an underwater environment in which cavitation, such as water temperature and dissolved amount of air, is unlikely to occur, as compared with Embodiment-5. 22
Is a high-pressure supply water, 23 is a high-pressure water supply channel, and 29 is a contraction part.

The groove bottom diameters d _{C 1} , d _{C 2} and d _{C 3} of the groove cavities 24-1 to 24-3 have a relationship of d _{C 1} <d _{C 2} <d _{C 3} (10). There, d _{C 1} = the diameter d _n of injection holes _{25 (1.1~1.4) d n ... (} 11) d C 2 = (1.2~1.6) d n ... (11) d _{C 3} = (1.4 to 1.8) d _n (11) Further, the width l _C1, l _{C 2} and l _{C 3} of the channel cavity 24-1～3, there is the order of _{l C 1 <l C 2 <} l C 3 ... size of (12). These are the length l of the ejection hole 25.
_{n C 1} = (0.07 to 0.25) l _n (13) l _{C 2} = (0.15 to 0.40) l _n (13) l _{C 3} = (0. 25 to 0.45) l _n (13) The inner diameter d _R of the ejection hole outer peripheral ring 27 is 2 times the diameter of the ejection hole 25 as in the following equation, as in Example-5.
Set up to 4 times.

D _R = (2-4) d _n (14) The length of the outer peripheral ring 27 may be slightly larger than the length of the outlet 25, although there may be some differences.
_{That, l R = (1.2~2.5) l} n ... (15) to (Embodiment -7) 20 and 21, the outlet of the injection holes 35, water nozzles provided Kiyabiteshiyon generation blade 34 The structure of is shown. The structure of the nozzle body 31 is basically the same as that of the embodiment shown in FIG. As shown in FIG. 25, the cavitation generating blade 34 has a role of stably generating the adhesive cavitation on the back side surface thereof, from which the cavities are slag-like (dispersed into fine bubbles later) in a submerged water jet. Of the cavitation bubbles are supplied stably.

In the figure, reference numeral 32 denotes high-pressure supply water, 3
3 is a high-pressure water supply channel, 36 is a central axis, and 37 is a contraction part.

FIG. 22 schematically shows a mechanism relating to the generation and growth of cavitation in the underwater nozzle having the structure shown in FIG. In the groove type cavity 4, gas serving as a bubble nucleus is always present as bubbles 4a trapped in the cavity. The dissolved gas in the water diffuses into the bubbles, and the bubbles grow as shown by 4b in the figure and separate from the groove-shaped cavity 4 (breakage of the cavity).

Immediately after the bubbles are ejected from the ejection holes 5, they are entrained in a vortex generated near the inner wall of the outer ring 7 of the ejection holes (4c), and are refined by the shearing action of the strong vortices (4d). The strong shearing action stimulates the bubble nuclei, which are unstable in water, so that the cavitation develops significantly here in a chain. The high-density and fine bubbles group amplified in this manner are ejected from the orifice outer peripheral ring 7 into the surrounding water (4e), and ride on the flow of the surrounding water entrained (4f) generated in the jet to form the inside of the cavitation jet. Disperse (diffuse) throughout (4h).

At the outer periphery of the underwater water jet, 4 g of cavitation bubbles derived from the shear vortex layer are generated, and these bubbles are dispersed throughout the cavitation jet similarly to the bubbles generated in the cavitator and the ring (4h). By the action as described above, a developed cavity jet suitable for peening is created.

FIG. 23 shows the behavior of bubbles in the grooved cavity 4 with respect to time [(a) → (e) →
Return to (a)]. First, there are bubbles trapped in cavities as shown in 5a. The dissolved gas in the water stream 2 diffuses into the bubbles and gradually grows (5b). The bubbles are largely deformed by the shearing action of the water stream 2 (5c), and break when the inertia force of the water stream 2 exceeds the interfacial tension, and the bubbles are separated from the grooved cavity 4 (5d). However, a part of the gas remains adhered in the groove type cavity 4 and becomes a new core. By such a cycle, the groove-type cavity 4 continuously supplies bubbles as a cavity. Groove type cavity 4
If it is too large, all gas will be removed from the cavity. On the other hand, if the groove-type cavity 4 is too small, the trapped bubbles will not grow because the interfacial tension will be dominant. Therefore, this groove-shaped cavity 4 is "disqualified" as a cavity except for the appropriate size range.
It is.

FIG. 24 schematically shows the behavior of bubbles and water flow in the underwater nozzle according to Example-6. From the groove-type cavities 24-1 to 3-3, which are the cavitators, cavitation bubbles are all generated, but they are successively united (6e), and large slag-like bubbles 6f are generated at the outlet of the ejection hole 25. This slag-like bubble 6f is deformed by the shearing action of the jet (6g). There is a strong vortex inside the orifice ring 27, and the slag-like bubbles 6f split into small bubbles in the vortex (6h). At the same time, bubble nuclei in the water are excited by the action of the vortex, and cavitation bubbles are generated in a chain.

By the same operation as described above, the cavitation bubbles are dispersed (diffused) into the jet (6i), and the developed cavitation jet 6j is realized. 6a-6c
Is the bubble trapped by the cavities, and 6d is the escape of the bubble.

FIG. 25 shows the phenomenon of cavitation in the seventh embodiment using a blade as a cavitator. On the back side of the cavitation generating blade 34, an abrupt pressure change field due to the vortex 7a is generated, giving an impression as if it is stuck at the same place in a sticky type (white appearance and "cloud" state). Cavitation occurs (7b). From this cavitation, the cavitation is broken almost continuously, and fine bubbles or slag-like bubbles are formed in the blade 3.
4 (7c). The divided cavitation bubbles are dispersed (diffused) into the cavitation jet 38 (7d), and produce the cavitation jet 38 that has developed while mixing with the water flow 7e.

FIG. 26 shows the results of an experiment for examining the effect of modifying the residual stress in the piping. In the case of using the conventional nozzle (Y), the effect of modifying the surface stress until the component in the tensile direction is almost eliminated is obtained, but the sufficient modifying effect is obtained such that the stress in the tensile direction changes to the compression side. Not.

On the other hand, it is understood that the use of the nozzle embodying the present invention has the effect of significantly improving the residual stress toward the compression side (Z). In the conventional nozzle, the development of the cavitation was insufficient, whereas in the nozzle according to the present invention, the collapse pressure of the bubbles in the developed cavitation jet was strong, so that a remarkable stress reforming effect was obtained. It is considered something. X indicates unprocessed.

(Embodiment-8) FIGS. 27 and 28 are drawings thereof.

An offset (axis shift) ε is given to both central axes of the central axis 52 of the water supply pipe parallel part and the central axis 54 of the jet hole in a parallel state without twist. In this embodiment, Di: diameter of parallel part of conduit Dj: diameter of ejection hole Lc: length of contraction portion Lj: length of ejection hole ε: offset distance of central axis Relationship. Outside of this range, problems such as reduced generation of cavitation, increased pressure loss, and difficulty in stabilizing the injection pressure occur.

Ε = (0.05 to 0.15) Lc (16-1) Dj = (0.03 to 0.15) Di (16-2) Lc = (2 to 5) Di (16) -3) Lj = (0.8-2) Dj (16-4) In the figure, 50 is a water injection nozzle main body, 51 is a parallel portion of a water supply conduit, 53 is high-pressure supply water, and 55 is a center of an ejection hole. Shaft 56 is a conduit contraction.

Embodiment 9 FIGS. 29 and 30 show the structure.

Basically, it is the same as the example shown in FIGS. 27 and 28, except that the central axis 60 of the parallel portion of the water supply conduit and the central axis 6 of the ejection hole are formed.
The offset distance of No. 5 is set to be relatively large. FIG.
As compared with the example of FIG. 28, the pressure loss is large and the injection system is somewhat uneconomical, but the cavitation occurs quite actively and the effect of surface stress modification is great. The following relations of the dimensions of each part of the nozzle are preferable in terms of performance.

Ε = (0.30-0.45) Lc (17-1) Dj = (0.03-0.15) Di ... (17-2) Lc = (2-5) Dj (17) -3) Lj = (0.8-2) Dj (17-4) In the figure, 61 is a parallel portion of the water supply conduit, 62 is a central axis of the parallel portion of the water supply conduit, 63 is high-pressure supply water, and 64 is a high-pressure supply water. An ejection hole, 66 is a conduit contraction part, 67 is a workpiece, and 68 is water.

Embodiment 10 FIGS. 31 and 32 show the structure.

Also in the nozzle of this embodiment, an offset (axis shift) of ε is provided between the central axis 72 of the water supply conduit parallel portion and the central axis 75 of the ejection hole 74. However, in Example-8,
Unlike FIG. 9, the conduit contraction portion 76 is formed axially symmetric. Therefore, the conduit contraction portion 76 and the ejection hole 74 are discontinuously connected. In the figure, it looks like there is a step at the connection on the left, but at this point the contraction occurs most rapidly,
The cavitation bubbles are actively generated. The shape of this nozzle can be expressed as follows.

Ε = (0.005 to 0.03) Lc (18-1) Dj = (0.03 to 0.15) Di (18-2) Lc = (2 to 5) Di (18) -3) Lj = (0.8-2) Dj (18-4) In the figure, 70 is a water injection nozzle main body, 71 is a water supply conduit parallel part, and 73 is high-pressure supply water.

Embodiment 11 FIGS. 33 and 34 show the structure.

In this nozzle, a conventional nozzle (FIG. 47)
On the other hand, only the ejection hole 84 is inclined at an angle θj (ejection hole inclination angle) with respect to the central axis 82 of the water supply conduit parallel portion. The water depressurized in the conduit contraction section 86 is rapidly changed its flow direction by the inclined jet holes 84, and the resulting turbulence excites the myriad of bubble nuclei inside the liquid, thereby greatly promoting the cavitation. You. In this nozzle, a jet is jetted at an angle θj from the nozzle body axis. The structure of this nozzle is as follows.

Ε = (0.005 to 0.03) Lc (19-1) Dj = (0.03 to 0.15) Di (19-2) Lc = (2 to 5) Di (19) -3) Lj = (0.8 to 2) Dj (19-4) θj ≦ 1.8 θc (19-5) where θc is the spreading angle of the conduit contraction portion 86. A nozzle body, 81 is a parallel portion of a water supply conduit, 83 is high-pressure supply water, and 85 is a central axis of the ejection hole.

Embodiment 12 FIGS. 35 and 36 show the structure.

In the nozzle of this embodiment, the conduit contraction portion 96
Is inclined by an angle θj with respect to the central axis 92 of the water supply conduit parallel portion corresponding to the axis of the nozzle body, and the central axis of the conduit contraction portion 96 is the same as the central axis 95 of the ejection hole 94. The jet is jetted at a far greater angle than the nozzle of Example-11 and at a tilt (angle θj) from the axis of the nozzle body. The structure of this nozzle is as follows.

Ε = (0.30-0.45) Lc (20-1) Dj = (0.03-0.15) Di ... (20-2) Lc = (2-5) Dj (20) -3) Lj = (0.8 to 2) Dj (20-4) θj ≦ 0.9θc ′ (20-5) where θc ′ is a double swing angle of the inclined conduit contraction portion. In the drawing, 90 is a water injection nozzle main body, 91 is a parallel portion of a water supply conduit, and 93 is high-pressure supply water.

(Embodiment 13) FIGS. 37 and 38 show the structure.

This nozzle is the same as the nozzle shown in FIGS. 27 and 28, except that the diameter of the outlet of the nozzle hole is slightly enlarged in the direction of the nozzle, that is, the nozzle is counterbore.
For the diameter Dj of the orifice 205, the orifice outlet enlarged portion 20
The maximum diameter Dd of 8 is desirably set in a relationship such as the following equation (21-5). The reason for sitting at the outlet of the orifice in this way is that cavitation occurs at the outlet of the orifice,
If the outlet is used for a long time, the outlet will be eroded and the outlet will be deformed. The shape of the orifice outlet has a non-negligible adverse effect on the state of cavitation.

Ε = (0.05-0.15) Lc (21-1) Dj = (0.03-0.15) Di ... (21-2) Lc = (2-5) Di ... (21) -3) Lj = (0.8 to 2) Dj (21-4) Dd ≦ (1.6 to 3) Dj (21-5) In the drawings, 201 denotes a water injection nozzle body, and 203
Is the central axis of the parallel part of the water supply conduit, 204 is high pressure supply water, 20
Numeral 5 denotes an orifice, 206 denotes a central axis of the orifice, and 207 denotes a conduit contraction part.

The nozzle of FIG. 40 is obtained by making the single-hole nozzle shown in FIGS. 37 and 38 porous as it is. Such a large-capacity nozzle is suitable for peening a large area portion. Of course, the injection pump also needs a correspondingly large capacity type.

In FIG. 40, reference numeral 301 denotes a water injection nozzle main body, 302 denotes a parallel portion of a water supply conduit, 303 denotes a central axis of the parallel portion of the water supply conduit, 304 denotes high-pressure supply water, 305 denotes a jet hole, and 306 denotes a jet hole center. Shaft, 307 is the conduit contraction, 30
Reference numeral 8 denotes an outlet opening enlarged portion, reference numeral 309 denotes a water injection gun, reference numeral 310 denotes a cap nut, reference numeral 311 denotes a water injection gun central axis, and reference numeral 312 denotes a water injection gun water supply pipe.

FIG. 41 shows an outline of the injection system. The high-pressure water 327 sent from the high-pressure water supply device is guided to the nozzle body 321 by the high-pressure water conduit 322, and is irradiated on the workpiece 324.

In the figure, 323 is a high-pressure water supply device, 325 is a cavitation jet, and 326 is a water environment.

Next, the operation will be described.

Here, the phenomenon and the peening effect due to the phenomenon will be described by taking the nozzle of the embodiment whose structure is shown in FIGS. 29 and 30 as an example.

FIG. 39 schematically illustrates the flow state in the nozzle. In this example, since there is an offset (axis shift) of ε between the central axis 62 of the water supply conduit parallel part and the central axis 65 of the ejection hole 64, the flow velocity in the radial direction of the conduit contraction part 66 (left and right sides in FIG. 39) is reduced. There is a big bias. In the orifice 64, abrupt contraction occurs on the side (left side in the figure) where the flow direction changes drastically at the conduit contraction part 66, and the flow separates from the inner wall of the orifice 64 (2 a). Fine bubbles (cavitation) are generated (2b).

In the orifice 64, a violent contraction was generated in part, but it did not occur (right side in the figure), and the jet was spouted into the water 68 by the action of the remarkable jet accompanied by the decompression. Active cavitation is continuously generated in the water jet. Eventually, the water jet jetted into the water from the nozzle of this embodiment becomes the submerged water jet (2c) with the developed cavitation.

The underwater water jet cavitation using the conventional nozzle (FIG. 47) without any countermeasures was intermittent, unstable, and required a large flow velocity (ie, high injection pressure). In this embodiment, even if the initial velocity at the ejection hole 64 is less than 10 m / s, a strong continuous cavitation water jet can be obtained. Numerous cavitation bubbles generated by the submerged water jet collide on or close to the solid surface, which is the workpiece 67, and collapse (crush) in a chain (2d), generating an impact pressure. I do. By this action, the residual stress in the tensile direction on the surface of the metal material is removed, and the surface is modified to the compression side.

Also in Embodiments 8 and 10 to 13, active cavitation jets are generated by an action similar to that described above. Comparing the performance of these nozzles, a general trend is that nozzles that can create a rapid contraction to activate the cavitation have a greater pressure loss. That is,
Higher injection pressure is required.

FIG. 42 shows an example of a construction test in which residual stress removal was verified. It is a measurement result in the piping part of 12 inches in diameter. It is possible to improve the tensile stress to a level of 0 with the conventional nozzle without any measures, but it can be seen that the nozzle according to the present invention is sufficiently stress-modified to the compression side. When using the nozzle according to the present invention, the irradiation time is also reduced by about 40% compared to when using the conventional nozzle.
Could be shortened.

(Embodiment 14) FIG. 43 shows the structure of a nozzle for underwater water jet as a sectional view passing through a central axis. The high-pressure water 342 is supplied through a high-pressure water conduit 344 that opens as a water supply unit on the upstream side of the nozzle body 341, and is decompressed and accelerated in the nozzle contraction unit 346.
It is sprayed into the surrounding environment water 350 from the nozzle outlet 347. At the exit of the nozzle ejection hole, a nozzle opening counterbore 348 is slightly cut. A plurality (three in this embodiment) of suction water thin tubes 349 having the other end opened on the outer surface of the nozzle body 341 are opened so as to communicate with the outlet side of the nozzle ejection hole 347.

Atmospheric water 350 is sucked into suction water capillary 349 as suction water 343 by the action of accelerating the high-speed water flow at nozzle ejection hole 347, and high-pressure water 342 supplied from the pump near the outlet of nozzle ejection hole 347 is provided. Combine and mix. In order to reduce the pressure loss at the time of suction, the diameter of the inlet portion of the suction water thin tube 349 is configured to increase as approaching the inlet portion. 345 is a nozzle center axis. FIG. 44 is an embodiment showing the opening-continuous state of the suction water capillary as a cross-sectional view perpendicular to the center axis 345 of the submerged water jet nozzle. That is, it is a nozzle in which a suction water capillary (orthogonal type) 349a and a nozzle ejection hole 347 are connected such that their central axes are orthogonal in this sectional view.

FIG. 45 is a graph showing the impact pressure distribution characteristics of the nozzle of Example 14 due to the cavitation jet.

In the nozzle embodying the present invention, the collision pressure is maximum on the jet center axis, and as described above,
It was confirmed that the cavitation was actively generated over the entire area of the cavitation jet. Also, compared with the conventional nozzle, the spread of the collision pressure is considerably wider,
The peening area by cavitation has expanded considerably,
It can be said that it is a characteristic that efficient peening can be expected.

FIG. 46 shows an experimental result obtained by examining the effect of modifying the residual stress in the piping. Even when a conventional nozzle is used, surface stress reforming until residual stress in the tensile direction disappears is obtained, but sufficient reforming effect such that the stress in the tensile direction changes to the compression side is not obtained.

On the other hand, it can be seen that the use of the nozzle embodying the present invention has the effect of significantly reducing the residual stress to the compression side. In the conventional nozzle, the development of cavitation is insufficient, whereas in the nozzle according to the present invention, the collapse pressure of bubbles in the developed cavitation jet is strong, so that a remarkable stress reforming effect is obtained. it is conceivable that.

When the nozzle according to the present invention is used for peening in shallow water, the suction water capillary 349 may be used.
Therefore, outside air may be sucked through the water surface. At this time, care must be taken because a large amount of air bubbles may fill the nozzle ejection holes 347 and cause the nozzle ejection holes 347 to be closed.

[0133]

The effects of implementing the present invention can be summarized as follows.

(1) The surface stress state of an underwater structure can be efficiently modified.

(2) Since no blast beads are used, it is not necessary to collect or discard them. The result is an economic operation.

(3) Since peening is performed in water, the temperature of the peening portion does not locally increase, so that the temperature of the target structure can be kept low and more uniform. (4) Noise can be prevented due to peening in water.

(5) As in the case of (4), since peening is performed in water, there is no need to worry about the disposition of droplets (splashing water droplets).

(6) Since the cavitation generated in the submerged water jet is effectively used, a predetermined effect can be obtained at a relatively low pressure. An ultra-high pressure water supply system (pumps, piping, valves, etc.) is not required, and equipment costs (initial costs) and operation costs (running costs) can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a nozzle.

FIG. 2 is a schematic diagram of a water supply system.

FIG. 3 is a schematic diagram showing a phenomenon in a case where there is no axial injection water.

FIG. 4 is a schematic diagram showing a phenomenon in a case where there is axial injection water.

FIG. 5 is a vertical sectional view of a nozzle.

FIG. 6 is a diagram schematically showing a phenomenon in a nozzle.

FIG. 7 is a schematic diagram of a water supply system.

FIG. 8 is a longitudinal sectional view of a nozzle.

FIG. 9 is a diagram schematically showing a phenomenon in a nozzle.

FIG. 10 is a schematic diagram of a water supply system.

FIG. 11 is a longitudinal sectional view of a nozzle.

12 is a longitudinal sectional view of the nozzle of FIG. 11 from another direction.

FIG. 13 is a plan view of the nozzle of FIG. 11;

FIG. 14 is a perspective view centered on a fan-shaped submerged water jet.

FIG. 15 is a view in the direction of arrows CC in FIG. 14;

FIG. 16 is a view showing a water injection supply system.

FIG. 17 is a diagram illustrating an example of a verification test result.

FIG. 18 is a longitudinal sectional view of a nozzle.

FIG. 19 is a vertical sectional view of a nozzle.

FIG. 20 is a longitudinal sectional view of a nozzle.

FIG. 21 is a view of the nozzle of FIG.

FIG. 22 is a diagram schematically showing a mechanism relating to generation and growth of cavitation in the nozzle of FIG. 18;

FIG. 23 is a diagram illustrating the behavior of bubbles in a grooved cavity as a change with time.

FIG. 24 is a view schematically showing the behavior of bubbles and a water flow in a nozzle.

FIG. 25 is a diagram schematically showing the phenomenon of cavitation.

FIG. 26 is a diagram showing an experimental result of examining the effect of modifying the residual stress in the pipe.

FIG. 27 is a longitudinal sectional view of a nozzle.

FIG. 28 is a plan view of the nozzle of FIG. 27.

FIG. 29 is a longitudinal sectional view of a nozzle.

FIG. 30 is a plan view of the nozzle of FIG. 29.

FIG. 31 is a longitudinal sectional view of a nozzle.

FIG. 32 is a plan view of the nozzle of FIG. 31.

FIG. 33 is a longitudinal sectional view of a nozzle.

FIG. 34 is a plan view of the nozzle of FIG. 33.

FIG. 35 is a longitudinal sectional view of a nozzle.

FIG. 36 is a plan view of the nozzle of FIG. 35.

FIG. 37 is a longitudinal sectional view of a nozzle.

FIG. 38 is a plan view of the nozzle of FIG. 37.

FIG. 39 is a view schematically showing a state of a flow in a nozzle.

FIG. 40 is a longitudinal sectional view of a nozzle.

FIG. 41 is a schematic diagram of an injection system.

FIG. 42 is a diagram showing an example of a construction test in which residual stress removal was demonstrated.

FIG. 43 is a longitudinal sectional view of a nozzle.

FIG. 44 is a diagram viewed from the line AA of FIG. 43.

FIG. 45 is a graph showing a collision pressure distribution characteristic due to a cavitation jet.

FIG. 46 is a diagram showing the results of an experiment in which the effect of modifying residual stress in a pipe was examined.

FIG. 47 is a view showing a state of ejection of a nozzle of a conventional example.

FIG. 48 is a view showing a state of ejection of a conventional nozzle.

FIG. 49 is a pressure decay characteristic diagram.

FIG. 50 is a longitudinal sectional view of a nozzle according to a conventional example.

FIG. 51 is a diagram showing a conventional structure for removing adhering contaminants.

FIG. 52 is a longitudinal sectional view of a nozzle according to a conventional example.

FIG. 53 is a longitudinal sectional view of a nozzle according to a conventional example.

FIG. 54 is a longitudinal sectional view of a nozzle according to a conventional example.

FIG. 55 is a view schematically showing a problem of the conventional example.

FIG. 56 is a view schematically showing a problem of the conventional example.

FIG. 57 is a diagram schematically showing a problem of the conventional example.

FIG. 58 is a longitudinal sectional view of a nozzle according to a conventional example.

[Explanation of symbols]

 Reference Signs List 101 Nozzle body 102 Main flow water conduit 103 Spout hole 105 Central axis 106 On-axis injection water flow pipe 107 On-axis injection water flow nozzle 108 On-axis injection high-pressure water 109 Workpiece 110 Main flow water supply unit 111 Main flow water remote conduit 112 On axis Injection water supply unit 113 On-axis injection water remote conduit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Kurosawa 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Inside the Hitachi Plant (56) References JP-A-61-146428 (JP, A) JP-A-57-41139 (JP, A) JP-A-2-222760 (JP, A) JP-A-5-195052 (JP, A) JP-A-2-145959 (JP, U) JP-A-4-54664 ( JP, U) Shokai 55-71000 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23P 17/00 B05B 1/02 C21D 7/04-7/06

Claims (4)

(57) [Claims] In a cavitation jet nozzle for improving the surface stress state of an object to be processed by jetting and impinging water in water, a second conduit is inserted into a first conduit having an ejection hole.
The nozzle of the second conduit is inserted into the outlet of the first conduit.
Inserted on the shaft to supply high-pressure water to the first conduit and the second conduit, respectively;
A second conduit is provided for the water jet in the outlet of the first conduit.
High-pressure water with different speeds is injected and mixed coaxially from the pipe nozzle.
A nozzle for jetting cavitation, characterized by being combined . 2. A method of jetting and colliding water in water.
Cavity to improve surface stress condition of workpiece
In the Yon jet nozzle, a nozzle reduction portion whose diameter gradually decreases, and the nozzle reduction portion
The smallest detail of the nozzle with a circular cross section provided at the tip of
Flat nozzle opening at the tip of the smallest nozzle
A cavity jet nozzle characterized by having a portion . 3. A method of jetting and colliding water in water.
Cavity to improve surface stress condition of workpiece
A high-pressure water supply flow path through which high-pressure water is supplied to a Yong jet nozzle;
A contracted portion having a contracted diameter provided at the tip of the flow path;
An orifice provided at the tip of the shrinking part to inject water into the water
An annular groove is formed on the inner wall of the ejection hole, and the groove bottom diameter dc of the annular groove is smaller than the diameter dn of the ejection hole.
In Te dc = (1.2~1.6) dn, wherein the width lc of the annular groove is lc = (0.15 to 0.40) ln the length ln of the ejection hole Nozzle for cavitation jet. 4. A method of causing water to impinge and collide in water.
Cavity to improve surface stress condition of workpiece
In the Yon jet nozzle, a small-diameter jet hole is provided at the tip
The central axis of the spout hole is aligned with the central axis of the water supply pipe parallel part.
And the gap between the water supply pipe parallel part and the ejection hole is inclined.
A nozzle for jetting cavitation, which is connected by a reduced portion .