JP4610989B2 - High frequency vibration horn and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high frequency vibration horn made of metal that is connected to a high frequency vibration generator and performs high frequency vibration in a liquid and generates cavitation bubbles on the tip side thereof to perform shot peening and the like, and a method of manufacturing the same.

  Conventionally, with respect to techniques such as shot peening, it has been generally performed to inject a steel ball or the like onto a workpiece. On the other hand, in recent years, shot peening using a cavitation technique by jet fluid injection has been proposed.

  In recent years, the applicant of the present application has proposed a technique for performing shot peening by performing high-frequency vibration, for example, ultrasonic vibration in a liquid connected to a high-frequency vibration generator and generating cavitation bubbles on the tip side thereof (for example, , See Patent Document 1). Here, a metal high-frequency vibration horn, that is, a horn of an ultrasonic transducer is applied.

  By the way, this horn is made of, for example, a metal such as a titanium alloy. However, when the tip of the horn is vibrated in a liquid, cavitation bubbles are generated at the tip of the horn, and the tip of the horn is caused by the cavitation bubbles. Easily eroded.

  As a countermeasure, a method of screwing ceramic parts or the like into the tip of the horn is applied. However, if the stroke of the horn becomes several tens to 100 μm, the ceramic portion cannot follow the extension of the horn, and thus it is damaged. Arise.

On the other hand, in the fields of sliding materials, fastening materials such as bolts and nuts, corrosion-resistant containers, eyeglass frames, and medical / dental materials, a technique for improving wear resistance by applying plasma treatment to titanium alloys has been proposed. (For example, see Patent Documents 2, 3, 4, etc.). However, in these techniques, the entire part is carburized.
JP 2003-220523 A JP-A-7-90542 JP 2001-152316 A JP 2002-88463 A

  Carburizing the entire horn made of titanium alloy or the like increases the hardness of the entire horn, changes the elastic coefficient, and inhibits vibration and elongation of the horn. That is, the stroke of the entire horn is reduced to a set value or less, and the stroke becomes smaller. For this reason, the effect of vibration of a predetermined stroke cannot be obtained.

  On the other hand, since erosion of the horn is caused by cavitation generated at the tip of the horn, it is desirable that only the tip is cured.

  The present invention has been made in view of such circumstances, and the hardened layer on the surface is difficult to peel off due to repeated expansion and contraction that occurs in the horn, and it is possible to suppress a decrease in vibration stroke due to expansion and contraction of the horn. An object of the present invention is to provide a high-frequency vibration horn and a method for manufacturing the same.

In order to achieve the above object, the invention according to claim 1 is made of a metal which is connected to a high-frequency vibration generator and performs high-frequency vibration in a liquid, and serves as a base material for generating cavitation bubbles on the tip side thereof. A horn for high-frequency vibration, in which a coating by carburizing treatment is formed on the outer peripheral surface and end surface of the tip side which is the base material, and the coating of the tip portion by this carburizing treatment has a hardness from the outer surface side toward the inner surface side A high-frequency vibration horn characterized by having an inclined structure that gradually changes to a low level and does not generate a hardness boundary surface with the base material of the horn, and the hardness of the coating is Hv 600 or more and 850 or less. provide.

If the hardness of the film is less than Hv600, the amount of erosion due to the cavitation increases, and if it exceeds 850, fine cracks are likely to occur on the carburized surface due to high-frequency vibration.

In the invention which concerns on Claim 2 , the stroke of the said horn provides the horn for high frequency vibrations which are 10 micrometers or more and 150 micrometers or less.

According to a third aspect of the present invention, there is provided a method for producing the high-frequency vibration horn according to the first aspect, wherein the front end portion of the horn is carburized by a low temperature plasma method. A manufacturing method is provided.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a high-frequency vibration horn in which masking is performed on a portion other than the tip side of the horn, and carburizing treatment is performed only on the tip side of the horn by low-temperature plasma treatment.

  According to the present invention, it is possible to reliably prevent erosion caused by cavitation generated at the horn tip. Moreover, since the boundary surface with the base material does not occur by continuously changing the hardness from the surface to the inside, the hardened layer on the surface is difficult to peel off due to repeated expansion and contraction. Furthermore, although the elastic coefficient of the horn surface changes due to surface hardening, the horn expansion and contraction is not inhibited by partially hardening the horn tip. That is, it is possible to suppress a decrease in vibration, and it is possible to maintain an effect due to a predetermined stroke vibration of the horn.

  Embodiments of a high-frequency vibration horn and a method for manufacturing the same according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a high-frequency vibration device applied to shot peening and the like, and FIG. 2 is an explanatory view showing a method for manufacturing a high-frequency vibration horn. FIG. 3 is a graph showing the effects.

  As shown in FIG. 1, the high-frequency vibration device of this embodiment is connected to a high-frequency vibration generator 2 that generates high-frequency vibration by energization from a high-frequency power source 1 and a piezoelectric ceramic vibrator 3 of the high-frequency vibration generator 2. The elongated horn 4 that vibrates at a high frequency, the support device 6 that supports the horn 4 and places the front end surface of the horn 4 parallel to the surface of the material 5 to be reformed, and the horn 4 and the material to be reformed A liquid holding device 8 including a container or the like in which the liquid 7 is interposed between the surface of the material 5 is provided. As a result, the horn 4 and the surface of the material to be modified 5 are immersed in the liquid 7.

  The vibrator 3 of the high-frequency vibration generator 2 is configured using a giant magnetostrictive material or a piezoelectric ceramic material, and the vibrator 3 is supplied with a high-frequency current from the high-frequency power source 1 and, for example, performs high-frequency vibration in the ultrasonic region. The horn 4 of the high-frequency vibration generator 2 is arranged facing the surface (upper surface) of the material 5 to be modified.

  An interval (gap) δ of, for example, 10 mm or less, preferably 0.1 to several mm (for example, 6 mm) is set between the lower surface, which is the tip of the horn 4, and the surface of the material 5 to be modified. In this state, the horn 4 reciprocates in the vertical direction (arrow a direction). The stroke of the horn 4 is set to 10 μm or more and 150 μm or less.

  When the horn 4 performs high-frequency reciprocal vibration, fine cavitation bubbles 9 are continuously generated in the liquid 7 interposed in the gap between the surface of the material 5 to be modified and the surface of the horn 4. Since the bubbles 9 are crushed one after another by the high-frequency reciprocating vibration 4, the bubbles 9 are continuously generated and collapsed.

  The surface of the horn 4 becomes below the saturated vapor pressure of the liquid, and cavitation bubbles 9 are generated. Similarly, the surface of the material to be reformed 5 facing the surface of the horn 4 becomes equal to or lower than the saturated vapor pressure of the liquid, and cavitation bubbles 9 are generated.

  Next, when the horn 4 instantaneously moves downward, the cavitation bubble 9 is crushed. When the cavitation bubble 9 is crushed, an ultrahigh pressure of several hundred megapascals is instantaneously generated and propagates around as a shock wave. This shock wave reaches the end face of the front end 4a of the horn 4 and the surface of the material 5 to be reformed, and a large shock force is applied to each of the surfaces, and the opposing surfaces are struck with a high shock wave. Thus, the impact force by cavitation can be formed on the surface of the material 5 to be reformed at high density.

  In such a configuration, a high impact force acts on the tip portion 4a of the horn 4, and there is a risk of erosion as described above. On the other hand, in the present embodiment, the outer peripheral surface 4b and the end surface 4c on the tip side of the portion that is connected to the high-frequency vibration generator 2 and performs high-frequency vibration in the liquid 7 and generates the cavitation bubbles 9 on the tip 4a side. A film 10 is formed by carburization.

  The coating 10 on the tip portion of the horn 4 by carburizing treatment has an inclined structure in which the hardness gradually decreases from the outer surface side toward the inner surface side, and no boundary surface of hardness is generated between the base material of the horn 4. Yes. And the hardness of the film | membrane 10 shall be Hv600 or more and 850 or less, for example.

  According to such a configuration, since the coating 10 is formed by carburization on the peripheral surface 4b and the end surface 4c on the tip side of the horn 4, erosion caused by cavitation occurring in this portion can be prevented. In addition, since the coating 10 is continuously changed in hardness from the surface to the inside thereof, a boundary surface with the base material of the horn 4 is not generated, and thus the hardened layer on the surface is difficult to peel off due to repeated expansion and contraction.

  Furthermore, although the elastic coefficient of the surface of the horn 4 changes due to surface hardening, the expansion and contraction of the horn 4 is not hindered because only the tip of the horn 4 is partially cured. That is, it becomes possible to suppress a decrease in vibration.

  Next, a method for manufacturing a high-frequency vibration horn and its operation will be described with reference to FIGS.

  As shown in FIG. 2, in the method of the present embodiment, a pair of electrodes 12 and 13 that are opposed to each other, for example, are provided in the vacuum furnace 11, and these electrodes 12 and 13 are connected to the plasma power supply device 14. ing.

A vacuum pump 15 and a gas supply device 16 are connected to the vacuum furnace 11 to adjust the degree of vacuum in the vacuum furnace 11 and supply reactive gases (for example, CH ₄ , C ₃ H ₈ , _{H 2} , Ar, etc.). It has come to be.

  In the vacuum furnace, the horn 4 is installed vertically on the lower electrode 13 in an upside down arrangement with respect to FIG. 1, and the tip 4 a of the upward horn 4 faces the upper electrode 12 with a predetermined distance.

  At the time of construction, the portion of the horn 4 excluding the front end 4a side is masked by the masking conductive case 17. Then, the inside of the vacuum furnace 11 is made a reactive gas atmosphere, and a high-voltage current is supplied from the plasma power supply device 14 to the electrodes 12 and 13.

  As a result, plasma 18 is generated on the surface of the tip portion 4a of the horn 4, and carburizing treatment by low temperature plasma treatment is performed only on the tip portion 4a side of the horn 4 that is not masked. That is, the carburizing process of the low temperature plasma method is performed.

  As a result, as described above, the coating 10 is formed by carburization on the outer peripheral surface 4b and the end surface 4c of the horn 4 on the front end 4a side.

  The coating 10 on the tip portion of the horn 4 by carburizing treatment has an inclined structure in which the hardness gradually decreases from the outer surface side toward the inner surface side, and no boundary surface of hardness is generated between the base material of the horn 4. Yes.

  FIG. 3 shows a test result when the carburizing treatment by the low temperature plasma method is applied to a titanium alloy horn (Ti-6Al-4V) as an example. The vertical axis of FIG. 3 represents Vickers hardness (Hvq0.245N), and the horizontal axis represents the depth (μm) from the surface.

Sample a is a case where the carburizing temperature is 850 ° C. and the processing time is 1 hour. Sample b is a case where the charcoal treatment temperature is 750 ° C. and the treatment time is 2 hours. Sample c is when the charcoal treatment is at a temperature of 810 ° C. and the treatment time is 2 hours. Sample d is a case where the charcoal treatment temperature is 690 ° C. and the treatment time is 3 hours.

Moreover, when the hardness of the film is less than Hv600, the amount of erosion due to the cavitation increases, and when it exceeds 850, it is recognized that fine cracks are likely to occur on the carburized surface due to high-frequency vibration.

  As shown in FIG. 3, each sample has a hardness of about 300 Hv in the interior of the horn 4 having a depth from the surface of 50 μm or more, like a normal titanium alloy, but the surface hardness is about 600 or more and about 850 Hv (average) It was confirmed that the surface hardness was extremely high.

  Further, the coating 10 on the tip portion of the horn 4 by carburizing treatment has an inclined structure in which the hardness gradually decreases from the outer surface side to the inner surface side, and no boundary surface of hardness is generated between the base material of the horn 4. It was confirmed that

  As a result, according to the present embodiment, erosion caused by cavitation occurring at the tip of the horn 4 can be reliably prevented. Moreover, since the boundary surface with the base material does not occur by continuously changing the hardness from the surface to the inside, it is possible to realize a material in which the cured layer on the surface is difficult to peel off due to repeated expansion and contraction.

  Furthermore, although the elastic coefficient of the surface of the horn 4 changes due to the surface hardening, according to the present embodiment, the distal end portion 4a of the horn 4 is partially hardened so that the expansion and contraction of the horn is not hindered. Can be suppressed, and unlike the case where the hardness of the entire horn 4 is increased, the vibration and elongation of the horn 4 are not hindered. That is, the stroke of the entire horn does not decrease below the set value, and the stroke does not change. Therefore, the effect by the predetermined stroke vibration of the horn 4 can be maintained.

Explanatory drawing which shows the high frequency vibration apparatus applied to shot peening etc. by embodiment of this invention. Explanatory drawing which shows the manufacturing method of the horn for high frequency vibration by embodiment of this invention. The graph which shows the effect by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency power supply 2 High frequency vibration generator 3 Vibrator 4 Horn 4a Horn tip part 4b Outer peripheral surface 4c End surface 5 Reformable material 6 Support device 7 Liquid 8 Liquid holding device 9 Cavitation bubble 10 Film 11 Vacuum furnace 12 Electrode 13 Electrode 14 Plasma power supply device 15 Vacuum pump 16 Gas supply device 17 Conductive case 18 for masking Plasma

Claims (4)

Is connected to the high frequency vibration generating device subjected to high-frequency vibrations in the liquid, a metal of a high-frequency vibration horn serving as a base material for generating cavitation bubbles at its tip side, the tip end side to be the base material A film formed by carburizing treatment is formed on the outer peripheral surface and the end surface, and the film of the tip portion by this carburizing treatment changes in hardness gradually from the outer surface side toward the inner surface side. A high-frequency vibration horn characterized by having an inclined structure that does not generate a surface and having a hardness of Hv600 or more and 850 or less . The horn for high-frequency vibration according to claim 1, wherein a stroke of the horn is 10 µm or more and 150 µm or less. 2. A method of manufacturing a high frequency vibration horn according to claim 1, wherein the surface of the tip of the horn is carburized by a low temperature plasma method. The method for manufacturing a horn for high-frequency vibration according to claim 3, wherein masking is performed on a portion excluding the tip side of the horn, and carburizing treatment is performed only on the tip side of the horn by low-temperature plasma treatment.

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