JPH11333724A - Method and device for peening by extra-high pressure water jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform peening of a material by moving extra-high pressure water jets on the metallic front surface until the metallic front surface to be peened is brought into contact with extra-high pressure water jets and compressed. SOLUTION: The front surface of a non-peened workpiece 1 is not applied is arranged near an extra-high pressure nozzle assembly 2. Extra-high pressure fluid is allowed to flow in the nozzle assembly 2. When extra-high pressure fluid is applied to the nozzle 2, extra-high pressure water jets 3 flow out from the nozzle 2, and the nozzle 2 is moved above the front surface of the workpiece 1. When the water jets 3 are contacted to the workpiece, the front surface 5 of the workpiece is recessed according to impact pressure of the water jets 3, and a peening surface 5 is formed. Therefore, peening force can be largely controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the processing of materials. In particular, the present invention relates to peening a surface of a material to change the properties of the material by locally compressing and consequently changing the crystal structure. The method of the present invention further includes using the vanishing particles entrained in the water stream, and an apparatus for performing the method.

[0002]

2. Description of the Related Art Conventionally, peening of a material has been performed in many ways. Peening is defined as the process of changing the surface of a material by impact. The peening process was originally developed according to the blacksmith's discovery that the metal hardened by repeatedly tapping the metal with a hammer, especially when the metal was hit without heating. If the metal is hot or if the metal is hit with a high temperature, the desired features are often lost. The process is often for this reason,
Called "cold working". The effect is somewhat similar to the phenomenon known as "work hardening". The use of peening results in increased resistance to corrosion and fatigue.

[0003] Today, peening processes typically involve air or centrifugal propelled shots to impact the surface of the material to be peened.
This is done using t). The shot may be either a metal shot or a ceramic sphere. The impact of the shot compresses the surface of the part beyond its yield strength, whereby the deep unyielded material holds the surface material in compression. Providing resistance to fatigue and corrosion is
This is the residual compressive stress of this surface. Today, peening is commonly used for a variety of metals such as iron alloys, titanium, honeycomb skins, and ISO grid panels, in addition to conventional materials. Shot peening,
It is used for shaping and processing the hardened surface of these materials. Peening is widely used in the nuclear and aviation industries.

[0004] The conventional shot peening method has several problems. Such issues include contamination, process control, and disposal of used shots. Many materials suffer from shot contamination, especially if the shot is made of metal. Small shots can block passages when used in areas such as aircraft engine parts. Shot contamination can alter the properties of the workpiece, including unwanted alloy formation and core nuclei. Process control is inherently difficult when dealing with ballistically propelled shots. Furthermore, a large shot does not reach a small radius and fillets and the like are improperly processed. Reducing the size of the shot does not always lead to a satisfactory solution. This is because small shots may not deliver enough energy to properly cold work the material, or may achieve the desired compression depth beyond the yield strength of the material to be peened. This is because they cannot. Finally, collecting used shots is often difficult, especially when the shots are made of ceramic (separation using magnetism is not possible). This problem is particularly acute when performing on-site peening of reactor components. In such a case, the waste shots may block important cooling passages and control passages. Damage to the cladding may damage the fuel bundle. Air can also cause contamination by floating metal particles in the air.

[0005] To address the above-mentioned problems with shot peening, it has been proposed to use a liquid jet to perform the peening process. One such proposal is described in U.S. Patent No. 5,305,361 to Enomoto. The Enomoto patent describes a process for peening a reactor component with a vibrating nozzle water stream. In the Enomoto patent, it is considered important to vibrate the nozzle to create a cavity in the jet. The collapse of these created cavities increases the force applied to the material to be peened. Enomoto teaches that it is not possible to use a non-oscillating jet because ultra-high pressure is required to deform the surface of the material. Obviously, Enomoto's patent is limited to the special case of peening the inner surface of a nuclear reactor that is underwater. In Enomoto's patent, at low pressures and high flow rates, the device must be fairly large and expensive to withstand the reaction forces due to flow, and the low pressure requires a fuel bundle before peening. Need to be taken out.

[0006]

It is an object of the present invention to provide a method and apparatus for peening a material by using an ultra-high pressure water stream.

[0007]

SUMMARY OF THE INVENTION The present invention is applicable to a variety of materials ranging from titanium to aluminum honeycomb. The present invention provides a method for controlling the peening force much greater than prior art methods. The present apparatus can perform peening of a shaped material that could not be peened by the conventional shot peening method. The method prevents contamination of the peened surface. Because shots are not used, there is no need to dispose of shots. The method can be implemented in a relatively inexpensive small device. There are no shots blocking small cavities.

[0008] The method uses at least one ultra-high pressure water jet nozzle. Ultra-high pressure fluid emerges from the nozzle and impacts the surface of the metal, which is separated by a small distance.
Ultra high pressure water is used to increase the velocity of the jet enough to cause the metal surface to yield directly or to accelerate particles (such as ice) in the fluid or to collapse by crushing cavity bubbles. Is required. The jet moves relative to the workpiece. This movement can be performed either by moving the workpiece in a plane or three-dimensional manner with respect to the jet, or by moving the jet itself.
One or two of the three directions can be rotated in this manner. The method further contemplates varying the speed and angle and force of such relative movement. Control of each of the above factors must be maintained to compensate for variations in any other factors.

[0009] The device of the present invention includes an ultra-high pressure water flow device.
The water flow device is provided with a suitable fluid supply device,
When using particles, a suitable particle supply device is provided. The water flow device is attached to a manipulator that can move a water flow in three directions. These dimensions are in conventional rectangular coordinate systems, depending on the application. Other applications require that the water flow be able to move on a plane, but there is no limitation on the degree of freedom of rotation. Finally, the water stream may be able to move along the line segment and has two degrees of freedom of rotation for the third type of application. In any of the three types of devices described above,
The movement of the workpiece can be replaced with the movement of the water flow, and a device for changing the peening force of the water flow during the peening operation is provided. In addition to changing the position and strength of the water flow, the relative movement speed can be continuously changed. The device controls all of these functions simultaneously and performs cold working of the material accurately.

[0010] Generally speaking, the method and apparatus of the present invention can peening a variety of materials into shapes that cannot be easily formed by conventional peening methods. Further, the method and apparatus of the present invention can perform peening in many environments not possible with conventional shot peening.

That is, the method of the present invention for peening a metal comprises the steps of generating an ultra-high pressure fluid, transporting the ultra-high pressure fluid to an ultra-high pressure water cutting nozzle, and releasing the ultra-high pressure fluid. Forming an ultra-high pressure water stream and contacting the ultra-high pressure water stream with the surface of the metal until substantially all of the surface of the metal to be peened is compressed in contact with the ultra-high pressure water stream. A step of moving the ultrahigh-pressure water stream over the surface of the metal to be peened so as to compress the water stream, and a step of stopping the operation of the water stream.

The pressure of the above fluid is 140.14 kg / cm ²
(20,000 psi) or more.

The pressure of the fluid is 3515.35 kg / cm ²
(50,000 psi) or more.

[0014] The moment of the water flow is preferably spiral.

The nozzle and the workpiece are preferably immersed in a liquid in order to enhance the effect of cavitation and the effect of peening.

The distance between the nozzle and the workpiece is
The workpiece may be selected to be sufficient to cold work the workpiece without substantially removing material from the workpiece.

In order to enhance the effectiveness of the peening process, the method preferably further includes a step of adding solid particles to the water stream.

Preferably, the solid particles disappear after completion of the peening process.

The solid particles are preferably ice.

The movement is performed by moving the water flow in a line, and then moving the water flow along an adjacent line until the entire surface of the metal to be peened is peened. Is good.

[0021] The peening machine of the present invention comprises a pump means for generating an ultra-high pressure fluid, a conduit means connected to the pump means for conveying the high pressure fluid, and a pump means for forming an ultra high pressure water flow. The ultra-high pressure water stream contacts and compresses the metal surface until substantially all of the nozzle means connected to the conduit means and the surface to be peened are compressed in contact with the water stream. like,
Converting means for moving the ultra-high pressure water stream over the surface of the metal to be peened.

The pressure of the above fluid is 140.14 kg / cm ²
(20,000 psi) or more.

The pressure of the fluid is 3515.35 kg / cm ²
(50,000 psi) or more.

[0024] The conversion means may move the water stream spirally.

In order to enhance the effect of cavitation and the effect of peening, it is preferable to further include a dipping means for dipping the nozzle and the metal in a liquid.

The distance between the nozzle and the workpiece is
The apparatus may further include a separation distance control means for adjusting the workpiece to be sufficient to cold work without substantially removing material from the workpiece.

In order to enhance the effectiveness of the peening process, it is preferable to further include an injection means for adding solid particles to the water stream.

It is preferable that the solid particles disappear after completion of the peening process.

The solid particles are preferably ice.

The conversion means moves the water stream in a line, and then moves the water stream along an adjacent line until the entire surface of the metal to be peened is peened. Good to do.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In all embodiments of the present invention, it has been found that several factors not previously considered are introduced into the process. The first of these factors is the incubation period (incubation
period). Cavitation studies have revealed the presence of an incubation period.
The incubation period is a period during which the action of the cavitation bubbles being crushed during this period is added to the material, but no material loss occurs. Ultra-high pressure water peening works during this period to cold work the workpiece without causing material loss.

The second factor is the determination and effect of the standoff in performing peening. The separation distance is a distance from the nozzle to the workpiece. The separation distance is
Determine the strength and mechanism of peening. When cutting by a water flow, it is desirable to arrange the nozzle as close as possible to the workpiece. In contrast, ultra-high pressure water jet peening requires a sufficient distance between the nozzle and the workpiece so that cavitation bubbles are formed and these bubbles collapse on the workpiece. If peening is performed only by impact pressure, the separation distance must be small. Thus, the optimum separation distance will vary according to the operating conditions.

The last factor is the effect of temperature. When the temperature of the fluid is near the boiling point, cavitation tends to occur. The present invention, in all embodiments, heats the fluid and greatly increases the cavitation and peening effects.

FIG. 1 is a front view of the method of the present invention. 1 shows an apparatus for implementing the method of the invention in its most basic form.

Workpiece 1 not subjected to peening
Is disposed near the ultra-high pressure nozzle assembly 2. The nozzle assembly 2 is provided with an ultra-high pressure fluid flow. For the purposes of the present invention, ultra-high pressure is defined as 1406.14kg / cm ² (20000psi) or more, preferably 3515.35kg / cm ² (50000
psi) or more. A suitable nozzle assembly is shown in U.S. Pat. No. 5,320,289. When an ultrahigh pressure fluid is added to the nozzle 2, an ultrahigh pressure water stream 3 exits the nozzle 2. The nozzle 2 is moved over the surface of the workpiece 1. When the water stream 3 hits the workpiece, the surface 5 of the workpiece yields according to the impact pressure of the water stream 3. As a result, the peening surface 5 is formed. The thrust load applied to the nozzle 2 is proportional to the flow rate multiplied by the square root of the pressure. For example, 421
If flow rate is per minute 9.46L (min 2.5 gallons) at a pressure of 8.42kg / cm ² (60000psi), it generates a relative thrust. The energy available for plastic deformation of the surface 1 is approximately the third power of pressure. This means that quadrupling the pressure increases the peening strength by a factor of 64. To generate this pressure and flow, 6
A pump of 600 kgm / s (88 hp) is required, and a large pump is more efficient.

In contrast, the pressure is 1054.61
The relative thrust of an oscillating pressure water stream at a pressure of (15000 psi) produces 4 relative thrusts at a flow of (20 gallons per minute). This nozzle requires a pump of 13200 kgm / s (176 hp) to generate 1/64 peening force. In order to generate sufficient peening strength in the ultra-high pressure nozzle, the high pressure oscillating nozzle requires an extremely large pump and a support structure to absorb the resistance.

FIG. 2 is a detailed perspective view of a second embodiment of the apparatus of the present invention. The embodiment shown in FIG.
Peening is applied to the inside of the. The water flow nozzle 11 is arranged in the workpiece 10. Work 1
0 is rotated 13 with respect to the nozzle 11. The rotation 13 can be performed by rotating the workpiece 10 or by rotating the nozzle 11. The water stream 12 is emitted from the nozzle 11 in close proximity to the workpiece 10. The nozzle 11 is adapted to move in a vertical direction 14 parallel to the length of the workpiece 10. In operation, the workpiece 10 is rotated along 13 and the nozzle moves in a vertical direction 14 such that the water stream 12 follows a spiral path along the entire inner surface of the workpiece 10. The peening operation is performed in the same manner as described in the detailed description of FIG.

FIG. 3 is a detailed perspective view of a third embodiment of the apparatus of the present invention. In a third embodiment, the workpiece 22 is mounted on a rotatable platter 20 and the platter 2
0 and the workpiece 22 can move in the direction of the arrow 23. The water flow nozzle 21 is arranged above and close to the workpiece 22. The water stream 25 is released from the nozzle 21 and the workpiece 2
Two hits. The nozzle 21 can move in the radial direction 24.
In operation, the workpiece 22 is rotated along 23 and the water flow 25
Moves the nozzle in a radial direction 24 so that the nozzle follows a spiral path along the entire upper surface of the workpiece 22. The peening operation is performed in the same manner as described in the detailed description of FIG.

FIG. 4 is a perspective view of an apparatus according to a third embodiment of the present invention. This device is particularly suitable for peening a surface of a material that can rotate about one axis of symmetry. Examples of such materials include disks, cylinders, cones, and spheres. The illustrated device is a prototype peening center. The components and parameters used are the same as for commercial systems. This device introduces some additional means for controlling the peening operation which are not provided in the devices of FIGS. 1, 2 and 3.

A workpiece 31 is mounted on a platter 32. In this figure, the workpiece 31 is a disk. The platter 32 is rotated by a motor 33. A water flow 36 is arranged above the workpiece 31. The water stream 36 can be moved by the traverse system 37 in the x-axis direction, that is, in the horizontal direction. The water flow 36 can be further moved by a traverse system 37 in the vertical direction, ie in the y-axis direction. The water stream 36 can be further moved in a horizontal direction, i.e., in the z-axis direction by a traverse system 37. xy
Traverse system 37, also called a -z manipulator, is a commercially available system that can move in all three orthogonal coordinates. Thus, in the illustrated device, the water flow can move in all directions along all rectangular coordinates. The workpiece 31 can move along the rotation axis of the platter 32. The illustrated apparatus is roughly the same as a milling machine capable of cold working an uneven surface in three directions. A high-pressure liquid is supplied to the water stream 36 from the ultra-high-pressure liquid pump 30 through the supply line 26. When particles such as ice and dry ice are used, they can be supplied from the hopper 31 via the metering / cutoff valve 32 and the supply line 33. Components 31, 33, 34, and 36
Is optionally contained in a water collection tank 34 which serves to contain the liquid to prevent contamination of the processing area. The operation of all components is performed by a computer 4 that interfaces with the system controller 42.
1 is controlled.

In order to operate the apparatus of FIG. 4, first, the workpiece 31 is mounted on the platter 32. In this embodiment, it is the disk that is subjected to peening. The motor 33 is started, and the rotation of the platter 32 and the workpiece 31 is started. The high pressure fluid is then supplied along with the particles from hopper 31 to water stream 36 via supply line 39. The traverse system 37 sweeps the water stream 36 over the entire upper surface of the workpiece 31. In operation, the water flow 36
Performs peening on the workpiece 31. This process is continued until the entire surface of the workpiece 31 is peened to a desired depth. When the peening has been performed to the desired extent, the pressure applied to stream 36 is reduced.

Controlling the scanning speed provides a second way to vary the degree of peening of the finished product. In this way, the center or any other part of the pocket can be peened deeper than at the edges. In another aspect, the peening speed can be controlled by changing the separation distance of the abrasive water stream 36 by the manipulator 38. This method can be used both for uniform peening and for compensating for changes in tangential speed due to the shape of the workpiece, as described above. The peening speed can also be controlled by the angle of the water stream 36 with respect to the workpiece 31. After completion of the peening process, it may be desirable to close valve 32 and remove workpiece 31. The device of FIG. 4 programs the shape of the workpiece into a computer,
It is equally applicable to peening cylindrical, conical or irregularly shaped objects.

FIG. 5 is a front sectional view of a fourth embodiment of the present invention in a nuclear reactor. As discussed above, nuclear reactors are particularly challenging environments for performing peening operations. In addition to cracks due to corrosion and cracks due to fatigue, there may be corrosion cracks due to radiation. For this reason, it has been proposed to peening the components of the reactor on site.
In this environment, shot loss and disposal are particularly problematic. Due to this problem, no on-site peening is performed today. The processes exemplified herein are applicable to boiling water reactors, pressurized water reactors, and any water moderator. The invention is illustrated for a boiling water reactor. For clarity, two identical crawlers 52 and 55 are shown.

The reactor 50 is a typical boiling water reactor having a shroud 51. Shroud 51 is typically made of austenitic stainless steel which is susceptible to intergranular stress corrosion cracking in the welded area. Clearly, cracking of the shroud 51 is undesirable. The peening process
In other applications, it has been found to be a satisfactory method for eliminating such cracks. Unfortunately,
Shot peening is not a satisfactory method due to processing problems and the above-mentioned problems with small radius fillets. Crawler vehicle
52 is provided with the ultrahigh-pressure water flow device of FIG. Returning to FIG. 5, an ultra-high pressure is applied to the crawler vehicle 52 from an ultra-high pressure pump 54 via a supply line 56. The supply line 56 is drawn into the support reel 57,
And pulled out and moved vertically. Support reel 5
7 is held on a support reel carriage 58 that can move around the shroud 52. Shroud 5
Movement of the carriage 58 around 2 is provided by drive sprockets 59 and 60. The control device 61
Information for controlling the sprockets 59 and 60 and the reel 57 is transmitted through the wire 62. A self-aligned vertical laser 63 mounted on the RPV stud is also mounted on the controller 61 and a data acquisition unit 66 provides information about the position of the vehicle 52 via wires 64 and provides feedback control of the vehicle 52. it can. Crawler 52 measures the degree of peening and returns the data to unit 66. The information is used to control the peening operation.

In operation, the crawler 52 is lowered by the reel 57 in a vertical line, and at this time, a vertical peening line is formed by activating an ultra-high pressure water flow. Next, the carriage 58 is advanced by the width of the peening line,
Repeat the work. The peening operation is performed in the same manner until the entire inner surface of the shroud 51 is peened. The operation is performed with the shroud filled with water.

In water, the working depth of the nozzle can be up to about 1
It has been found that the deeper at about 3.7 feet (45 feet), the more effective the water flow. this is,
This is probably because the effect of the collapse of the bubbles is strong. This effect disappears as the depth increases.
This is because the formation of cavitation bubbles is suppressed and
This is because it becomes the same as the air pressure near 7.43 m (90 ft).

The above-described embodiments are merely illustrative of the present invention and are defined solely by the appended claims.

[Brief description of the drawings]

FIG. 1 is a front view of the method of the present invention.

FIG. 2 is a detailed perspective view of a second embodiment of the device of the present invention.

FIG. 3 is a detailed perspective view of a third embodiment of the device of the present invention.

FIG. 4 is a perspective view of the embodiment of FIG.

FIG. 5 is a front sectional view of a fourth embodiment of the present invention used in a nuclear reactor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Workpiece 2 Ultra high pressure nozzle assembly 3 Ultra high pressure water flow 5 Peening surface

 ────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 598068666 21414-68th Ave, Kent, Washington 98032, United States of America (72) Inventor Dave Monsrad 98117, Washington, United States of America 98117, Seattle, Northwest Seventies 3026 ( 72) Inventor Dave Bothell 21414 (72) Inventor Dave Steele, United States 98032, Kent, Sixty Ace Avenue 21414 (72) Inventor John John, 98032, Kent, United States Hake Washington, USA 98103, Seattle, Bagley Avenue North 4017

Claims (20)

[Claims] 1. A method for peening a metal, comprising: generating an ultra-high pressure fluid; conveying the ultra-high pressure fluid to an ultra-high pressure water jet cutting nozzle; Forming a high pressure water stream; and contacting the ultra high pressure water stream with the metal surface until substantially all of the surface of the metal to be peened is compressed in contact with the ultra high pressure water stream. A method comprising: moving the ultra-high pressure water stream over a surface of a metal to be peened to compress; and deactivating the water stream. 2. The pressure of the fluid is 1406.14 kg / c.
is m ² (20000psi) above, the metal peening method according to claim 1. 3. The pressure of the fluid is 3515.35 kg / c.
It is m ² (50,000 psi) or more, the metal peening method according to claim 1. 4. The method according to claim 1, wherein the moment of the water stream spirals. 5. The metal peening method according to claim 1, wherein the nozzle and the workpiece are immersed in a liquid in order to enhance the effect of cavitation and increase the effect of peening. 6. The distance between the nozzle and the workpiece is selected to be sufficient to cold work the workpiece without substantially removing material from the workpiece. The metal peening method according to claim 1. 7. In order to enhance the effectiveness of the peening process,
The metal peening method according to claim 1, further comprising a step of adding solid particles to the water stream. 8. The metal peening method according to claim 7, wherein the solid particles disappear after completion of the peening process. 9. The method of claim 8, wherein the solid particles are ice. 10. The movement comprises moving the stream in a line, and then flowing the stream along an adjacent line until the entire surface of the metal to be peened is peened. The metal peening method according to claim 1, wherein the method is moving. 11. A pump means for generating an ultra-high pressure fluid, a conduit means connected to said pump means for conveying said high pressure fluid, and a conduit means connected to said conduit means for forming an ultra high pressure water flow. Nozzle means, and the ultra-high pressure water stream contacts and compresses the metal surface until substantially all of the surface to be peened is compressed in contact with the water stream. Converting means for moving the high-pressure water stream over the surface of the metal to be peened. 12. The pressure of the fluid is 1406.14 kg.
/ cm at ² (20000psi) above, peening machine according to claim 11. 13. The pressure of the fluid is 3515.35 kg.
/ cm at ² (50,000 psi) or more, peening machine according to claim 12. 14. The peening machine according to claim 11, wherein the converting means spirally moves the water stream. 15. The peening machine according to claim 11, further comprising immersion means for immersing the nozzle and the metal in a liquid in order to enhance the effect of cavitation and enhance the effect of peening. 16. A separation for adjusting a distance between the nozzle and the workpiece to be sufficient to cold work the workpiece without substantially removing material from the workpiece. The peening machine according to claim 11, further comprising a distance control unit. 17. The peening machine according to claim 11, further comprising an injection means for adding solid particles to the water stream to enhance the effectiveness of the peening process. 18. The peening machine according to claim 17, wherein the solid particles disappear after completion of the peening process. 19. The solid particles of claim 18, wherein the solid particles are ice.
The peening machine described in. 20. The conversion means moves the water stream in a line, and then moves the water stream along adjacent lines until the entire surface of the metal to be peened is peened. 19. The peening machine according to claim 18, wherein the peening machine moves.