JP2009090443A - Surface reformer and surface reforming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface reforming technique for a member to be reformed such as a metal, particularly, a surface reformer for imparting a peening effect to the member to be reformed arranged at a specified interval from the reformer without applying an excessive pressure and also provide a surface reforming method. <P>SOLUTION: This surface reformer 1 comprises: a high-frequency oscillation generating means 2 for generating high-frequency oscillation; a high-frequency oscillation means 2e connected to the high-frequency oscillation generating means and performing high-frequency oscillation; a supporting means 3 for supporting the reformed surface 9a of the member to be reformed 9 and the end 2f of the high-frequency oscillation means with a gap interposed therebetween; a pressure water supply means 6 for supplying pressure water 7a to a jet generating means 5; and a liquid holding means 11 for interposing a liquid 11a at least in the gap between the end 5b of the jet generating means 5 and the member to be reformed 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface modification technique for a material to be reformed such as metal, and in particular, a surface reforming apparatus for imparting a peening effect to a material to be reformed having a certain distance using a low-pressure jet and a modification thereof. On quality methods.

  Conventionally, there has been proposed a water jet peening apparatus and a water jet peening method for improving a residual stress of an underwater object by colliding a high-speed underwater jet accompanied by cavitation bubbles with the surface of a work (see Patent Document 1). According to this, cavitation bubbles are generated in a jet of a large amount of high-pressure water pressurized to a high pressure by a pump in order to obtain an underwater high-speed jet. Furthermore, this high pressure water was sprayed from the nozzle, and the cavitation bubble contained in this high pressure water collided with the surface of a construction object, and the shock wave generated by collapsing was irradiated, and the peening effect was provided.

A surface modification method and apparatus for generating cavitation bubbles generated by high-frequency vibration of a diaphragm have also been proposed (see Patent Document 2). According to this, a peening effect is imparted by irradiating a shock wave generated by the collapse of the cavitation bubbles on the surface of the work piece disposed opposite to the diaphragm.
JP 7-328858 A JP 2003-220523 A

  Since the water jet peening apparatus and the water jet peening method shown in Patent Document 1 generate and transport cavitation bubbles using a high-speed jet, there is no need to maintain the distance from the outlet to the material to be modified with high accuracy. It was. However, since a large amount of high-pressure water of several tens of MPa is used to obtain a high-speed submerged jet, the flow of the impinging jet differs depending on the shape of the material to be reformed, and the generation of cavitation bubbles is processed under a certain condition that is optimal for processing. It was difficult to maintain. In addition, it is difficult to effectively process a curved surface that changes in a complicated manner and to apply a compressive residual stress having a uniform and constant depth to the curved surface. Furthermore, it is difficult to control the jet flow, and it is difficult to construct a narrow space such as a hole or a cylindrical inner surface. Furthermore, since high-pressure water is used, there is an adverse effect that an excessive pressure load other than the construction surface acts.

  Further, the surface modification method and apparatus shown in Patent Document 2 are effective and effective in that high pressure water is not required because cavitation bubbles are generated by a diaphragm that vibrates at high frequency. However, in order to generate a shock wave of several hundred MPa by collapse of cavitation bubbles generated from the diaphragm, it is necessary to generate cavitation bubbles in a high density state. Along with this, the distance between the diaphragm and the material to be reformed must be accurately maintained at a fine distance of 10 mm or less, preferably 0.1 mm to several mm. In addition, it is difficult to apply the material to be reformed having a distance of 10 mm or more from the diaphragm, for example, about 20 mm or 30 mm.

  For this reason, the jet which is the characteristic of the water jet peening apparatus and the water jet peening method disclosed in Patent Document 1, while utilizing the controllability of the shock wave to the material to be modified which is the characteristic of the surface modification method and apparatus disclosed in Patent Document 2. There has been a need for a peening technique that has the ability to transport cavitation bubbles to the material to be reformed using slag.

  The present invention has been made in view of such circumstances, and provides a surface reforming apparatus and a method for reforming the same that give a peening effect to a material to be reformed having a certain distance using a low-pressure jet. The purpose is to do.

  In order to solve the above-described problems, a surface modification apparatus according to the present invention includes a high-frequency vibration generating unit that generates high-frequency vibrations, a high-frequency vibration unit that is connected to the high-frequency vibration generating unit, and that performs high-frequency vibrations; A support means for supporting the construction surface of the material and the tip portion of the high-frequency vibration means with a gap therebetween, a jet generating means held on at least the outer surface of the high-frequency vibration means, and the jet flow The generating means includes pressure water supplying means for supplying pressure water, and liquid holding means for interposing liquid in at least a gap between the tip of the jet generating means and the material to be reformed.

  In addition, in order to solve the above-described problems, the surface modification method according to the present invention generates cavitation bubbles by a high-frequency vibration generation step that generates high-frequency vibration and the high-frequency vibration generated in the high-frequency vibration generation step. And a mixing step of supplying and mixing pressure water to the cavitation bubbles generated in the step of generating the cavitation bubbles, and a construction of the material to be modified using the pressure water mixed with the cavitation bubbles in the mixing step. And a step of generating a shock wave by applying a peening effect by ejecting to the surface and collapsing the cavitation bubbles.

  The surface modification apparatus and the modification method according to the present invention can impart a peening effect to a material to be modified having a certain distance using a low-pressure jet.

  Embodiments of a surface modification apparatus and a modification method thereof according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
This surface modification device irradiates the surface of a material to be reformed such as metal with a shock wave generated by the collapse of cavitation bubbles, and imparts a peening effect. To improve fatigue strength.

  The peening effect is an effect of improving surface fatigue strength, wear resistance, stress corrosion resistance, and the like by applying compressive stress to the surface of the material to be modified.

  FIG. 1 is a configuration diagram illustrating an example of a surface modification apparatus according to the present embodiment.

  The main structure of the surface modification apparatus 1 in FIG. 1 is a high-frequency power supply device 2 as high-frequency vibration generating means, a piezoelectric element 2a as a vibrating portion, a horn 2e as high-frequency vibration means, and a nozzle holder 5 as jet generating means. The nozzle holder 5 includes a nozzle 5b and a water tank 11 in which the material to be modified 9 is immersed in fresh water 11a. Moreover, it is a pressure water supply means, Comprising: The supply pump 6 which supplies the fresh water 7a which is a pressure water to the nozzle holder 5 from the fresh water supply port 5c provided in the nozzle holder 5, the water tank 7 which stores the fresh water 7a, etc. .

  The high frequency power supply device 2 supplies a high frequency alternating current to the piezoelectric element 2a connected by the cable 2d. The piezoelectric element 2a is made of a giant magnetostrictive material or a piezoelectric ceramic material, and generates high-frequency vibration by a high-frequency current supplied from the high-frequency power supply device 2. The piezoelectric element 2a is fixed to the shaft 2c by a fastening body 2b.

  The horn 2e is fixed to the shaft 2c by the mounting flange 2h, and vibrates in the vertical direction (y-axis direction) perpendicular to the construction surface 9a of the material 9 to be reformed by transmitting the vibration of the piezoelectric element 2a. It is supposed to be. The horn 2e generates cavitation bubbles 8a at the horn tip 2f by performing high-frequency vibration. The horn tip 2f is made of a high hardness material such as cemented carbide or ceramics in order to prevent erosion due to the cavitation bubbles 8a.

  Here, the frequency of the high-frequency vibration is, for example, 500 Hz or more, and preferably 20 kHz to 80 kHz which is an ultrasonic region.

  The mounting flange 2h is provided at a nodal point (axial vibration node) in the shaft 2c. The mounting flange 2 h is connected to the mounting arm 3 by a bolt 3 a and is fixed to the stationary portion 4. Moreover, these are comprised so that the clearance gap may be provided in the position which opposes the construction surface 9a of the to-be-modified material 9, and the horn front-end | tip part 2f, and functions as a support means.

  The nozzle holder 5 is installed so as to cover the periphery of the horn 2e, and has a function of generating a cavitation jet 8 including cavitation bubbles 8a generated from the horn tip 2f. The nozzle holder 5 is held on the outer surface of the horn 2e, and is configured in a non-contact state with the horn 2e in the present embodiment.

  At the upper end of the nozzle holder 5, a seal portion 5a that is a minute gap with the horn 2e is provided. A nozzle 5 b is provided at the lower end of the nozzle holder 5, and a jet 8 d is jetted from the nozzle 5 b toward the material to be reformed 9. Also, the nozzle holder 5 has a throat-like shape from the space 5d formed at the lower part of the horn tip 2f to the jet outlet 5b, and can effectively generate the jet 8d. .

  The nozzle holder 5 is provided with pressure water supply means. This pressure water supply means pressurizes the fresh water 7a from the water tank 7 for storing the fresh water 7a as the pressure water, passes the supply pipe 6a, and supplies the fresh water 7a as the pressure water from the fresh water supply port 5c to the nozzle holder 5. The supply pump 6 is configured.

The fresh water 7a as pressure water which is pressurized by the supply pump 6 and supplied from the fresh water supply port 5c to the nozzle holder 5 is low-pressure water of about 1 to several tens kgf / cm ² . In the conventional water jet peening method, since a high-pressure jet was generated using high-pressure water, a large amount of fresh water was required. On the other hand, the surface reformer in this embodiment uses low-pressure water. This is effective in that the amount of fresh water can be reduced.

  The nozzle holder 5 includes a cavitation generating portion 12 formed by a range where the cavitation bubbles 8a generated from the horn tip portion 2f are constantly present. In the cavitation generator 12, the cavitation bubbles 8a generated from the horn tip 2f and the fresh water 7a supplied as low-pressure water by the supply pump 6 are mixed and stirred. At the horn tip 2f, a pressure wave is generated by the high frequency vibration of the horn 2e as well as the cavitation bubbles 8a. The mixed and stirred cavitation bubbles 8a and fresh water 7a become a cavitation jet 8 due to the influence of this pressure wave, and are jetted from the outlet 5b of the nozzle holder 5 to the construction surface 9a of the material 9 to be reformed in a low pressure state. It has become so.

  The water tank 11 as a liquid holding means is provided below the jet outlet 5 b of the nozzle holder 5. Fresh water 11 a is stored in the water tank 11, and a fluid is interposed in the gap between the material to be reformed 9 and the nozzle holder 5 installed at the bottom of the water tank 11, for example.

  Next, the operation of the surface modification device 1 will be described.

  FIG. 2 is an enlarged view when the jet flow 8 d ejected from the ejection port 5 b of the nozzle holder 5 in the surface modification device 1 acts on the construction surface 9 a of the material 9 to be reformed. The construction surface 9 a that is the material to be modified 9 is immersed and fixed in the fresh water 9 stored in the water tank 11.

  The jet 8d in FIG. 2 is generated when the cavitation jet 8 generated in the cavitation generator 12 is jetted from the nozzle outlet of the nozzle holder 5. This jet 8d is jetted in a state where clean water 7a as low-pressure water and a large amount of cavitation bubbles 8a are mixed and stirred, and collides with the construction surface 9a. When it collides with the construction surface 9a, the cavitation bubbles 8a included in the jet 8d are collapsed by impact, and a shock wave is instantaneously generated by this collapse, and a peening effect is given to the construction surface 9a.

  FIG. 3 is a diagram illustrating a peening effect that acts on the construction surface 9a in the surface modification device 1. FIG.

  When the jet flow 8d containing a large amount of cavitation bubbles 8a collides with the construction surface 9a, the cavitation bubbles 8a collapse on the construction surface 9a due to the surrounding pressure action and burst as collapsed bubbles 8b. The collapsed bubbles 8b instantaneously generate a large shock wave 8c of several hundred MPa toward the periphery of the collapsed bubbles 8b. When the cavitation bubble 8a in the vicinity of the construction surface 9a collapses, a part of these shock waves 8c acts directly on the construction surface 9a to give a cavitation effect.

  The generation time of the shock wave 8c generated in one cavitation bubble 8a is a very short time of several microseconds, but by continuously collapsing a large amount of cavitation bubbles 8a in a high density state, It becomes possible to make the shock wave 8c act continuously.

  The shock wave 8a generated by the collapse of the cavitation bubble 8a is applied to the work surface 9a, thereby hardening the work surface 9a and applying compressive residual stress to the surface of the material 9 to be modified. The fatigue strength, wear resistance, stress corrosion resistance and the like of the modifier 9 can be improved.

  According to this surface modification apparatus and surface modification method, the flat work surface can be obtained without using a high-pressure jet that lacks controllability as in the prior art by providing the nozzle holder 5 and generating the jet 8d. Of course, cavitation bubbles 8a can be transported by a low-pressure jet to a complicated construction, and a peening effect can be imparted.

  In addition, since the low-pressure jet is irradiated onto the construction surface 9a, a high-speed flow does not occur as in the conventional case, and it is possible to irradiate the complicated construction surface with the secondary flow of the high-pressure jet. There is no adverse effect such as excessive pressure load on structures other than materials.

  Further, in order to convey and collapse the cavitation bubbles 8a to the construction surface 9a of the material 9 to be reformed using the jet 8d, the nozzle holder 5 and the construction surface as in the surface modification method and apparatus shown in Patent Document 2. The distance from 9a does not need to maintain a minute gap with high accuracy. For this reason, even if this distance changes somewhat, it does not have a big influence on a peening effect, and it is effective at the point which can give a peening effect even if it has a fixed distance, for example, a distance of about 20 mm-30 mm. .

[Second Embodiment]
In the second embodiment, a surface modifying device capable of irradiating a material to be reformed with a higher density of shock waves by causing a larger amount of cavitation bubbles contained in a jet generated from the surface modifying device to exist, and its The reforming method will be described.

  FIG. 4 is a configuration diagram of the surface modification apparatus 1 in the second embodiment.

  In addition, about the structure and part corresponding to 1st Embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In addition to the configuration of the surface modification apparatus 1 in the first embodiment shown in FIG. 1, the surface modification apparatus 1 in FIG. 4 is provided with air mixing means in the pressure water supply means. Specifically, an air mixing device 10 and an intake pipe 10a are further provided in the supply pump 6 and the water tank 7 which are pressure supply means.

  The air mixing device 10 is provided to mix the air sucked from the intake pipe 10 a and the fresh water 7 a pressurized from the water tank 7 by the supply pump 6. The fresh water 7a primarily mixed with air in the air mixing device 10 generates a gas-liquid two-phase flow and is supplied to the nozzle holder 5 from the fresh water supply port 5c.

  Fresh water 7a as pressure water that is in a gas-liquid two-phase flow supplied to the nozzle holder 5 is generated by the cavitation generator 12 as finer cavitation bubbles 8a. For this reason, the cavitation jet 8 contains a larger amount of cavitation bubbles 8a. As a result, a large amount of cavitation bubbles 8a can also be included in the jet flow 8d acting on the construction surface 9a of the material 9 to be modified, and the shock waves 8c in a high density state are applied to the construction surface by the collapse of the large amount of cavitation bubbles 8a. It becomes possible to irradiate 9a.

  Since the operation of the surface modification apparatus 1 is the same as that of the first embodiment, the description thereof is omitted.

  According to this surface reforming apparatus and its reforming method, in addition to the effects produced in the first embodiment, a larger amount of cavitation bubbles 8a can be generated by providing air mixing means in the pressure water supply means. The construction surface can be irradiated with shock waves in a high density state. As a result, the peening effect can be applied more effectively to the material to be modified, and the fatigue strength, abrasion resistance, stress corrosion resistance, etc. of the surface of the material to be modified can be further improved. .

The block diagram which shows the surface modification apparatus in 1st Embodiment. The enlarged view at the time of the jet flow ejected from the jet nozzle of the nozzle holder acting on the construction surface of the material to be reformed. The figure explaining the peening effect which acts on the construction surface in a surface modification apparatus. The block diagram which shows the surface modification apparatus in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface modification apparatus 2 High frequency power supply apparatus 2a Piezoelectric element 2c Shaft 2e Horn 2f Horn tip part 3 Mounting arm 3a Bolt 4 Stationary part 5 Nozzle holder 5a Seal part 5b Spout 5c Fresh water supply port 6 Supply pump 7 Water tank 7a Fresh water 8 Cavitation Jet 8a Cavitation bubble 8b Collapsed bubble 8c Shock wave 8d Jet 9 Reformed material 9a Construction surface 10 Air mixing device 10a Intake pipe 11 Water tank 11a Fresh water 12 Cavitation generation part

Claims (8)

High-frequency vibration generating means for generating high-frequency vibration;
High-frequency vibration means coupled to the high-frequency vibration generating means for performing high-frequency vibration;
A supporting means for supporting the construction surface of the material to be modified and the tip of the high-frequency vibration means by providing a gap at a position facing each other;
Jet generation means held on the outer surface of at least the tip of the high-frequency vibration means;
Pressure water supply means for supplying pressure water to the jet flow generating means;
A surface reforming apparatus comprising: a liquid holding unit for interposing a liquid in at least a gap between the tip of the jet generating unit and the material to be reformed. The surface modification apparatus according to claim 1, wherein the high-frequency vibration generating means generates vibration in an ultrasonic region. ^2. The surface reforming apparatus according to claim 1, wherein the pressure water supplied to the jet generating means by the pressure water supplying means is 1 to several tens kgf / cm < ² >. 2. The surface reforming apparatus according to claim 1, wherein the pressure water supply means further includes an air mixing means for mixing air with the pressure water in order to make the pressure water into a gas-liquid two-phase flow. The surface reforming apparatus according to claim 1, wherein the jet outlet of the jet generating means is configured in a throat shape. 2. The surface modification apparatus according to claim 1, wherein the high-frequency vibration generating means includes a vibration part made of a giant magnetostrictive material or a piezoelectric ceramic material. 2. The surface modification apparatus according to claim 1, wherein the tip of the high-frequency vibration means is made of a high hardness material. A high-frequency vibration generating step for generating high-frequency vibration;
A step of generating cavitation bubbles by the high-frequency vibration generated in the high-frequency vibration generation step;
A mixing step of supplying pressure water to the cavitation bubbles generated in the step of generating the cavitation bubbles and mixing them;
And jetting the pressure water mixed with the cavitation bubbles in the mixing step onto a construction surface of the material to be reformed, generating a shock wave by collapsing the cavitation bubbles, and providing a peening effect. A characteristic surface modification method.

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