Ultrasonic treatment method and ultrasonic treatment apparatus

Abstract

To propagate ultrasonic waves more reliably to a plurality of treatment objects (S) to achieve more uniform surface treatment. A surface treatment is performed while applying ultrasonic waves to the plurality of treatment objects (S) immersed in a treatment liquid (3) filled in a treatment tank (10) equipped with an ultrasonic application mechanism (20). Each treatment object (S) is arranged to be in contact with other treatment objects (S) at least at two points. A hollow reflection vibrator (30) immersed in the treatment liquid (3) is arranged in the treatment tank (10) to be in contact with other treatment objects (S) at least at two points. A ratio Dr / Ds of a maximum value Ds of an outer diameter of the treatment object (S) to a maximum value Dr of an outer diameter of the reflection vibrator is 0.2 to 6.0, a specific acoustic impedance Zr of the reflection vibrator (30) is 1 x 10⁷ to 2 x 10⁸ kg·m-⁻²·sec⁻¹, and a hollow portion of the reflection vibrator (30) is filled with a liquid or gas having a specific acoustic impedance Zi different from the specific acoustic impedance Zr.

Description

Ultrasonic treatment method and ultrasonic treatment device

[0001] The present invention relates to an ultrasonic processing method and an ultrasonic processing apparatus.

[0002] In general, in the manufacturing process of various metal bodies such as steel plates and steel pipes, a cleaning method is widely adopted in which the metal body is immersed in a cleaning tank containing a chemical solution (e.g., an alkaline degreasing agent, a surfactant, a sulfuric acid solution, etc.), a rinse, etc., to remove dirt, scale, etc. present on the surface of the metal body. Cleaning treatment devices that perform such cleaning treatment methods include, for example, a treatment device that uses a high-pressure air jet nozzle and an ultrasonic treatment device that uses ultrasound.

[0003] Here, when performing various surface treatments, including cleaning treatments, on large materials such as steel plates and steel pipes, in order to improve the conductivity and uniformity of ultrasonic waves, ultrasonic waves are applied while moving the vibrator as in Patent Document 1 below, or an ultrasonic wave reflecting member is provided in the treatment tank as in Patent Document 2 below.

[0004] Japanese Patent Application Laid-Open No. 9-143767 International Publication No. 2018 / 169050

[0005] In order to further improve the efficiency of surface treatment, it is conceivable to group multiple workpieces into an aggregate and then perform treatment on this aggregate. In this case, it is considered that the degree of ultrasonic application to the workpieces located inside the aggregate is lower than that to the workpieces located on the outer edge of the aggregate. Therefore, even if the techniques disclosed in Patent Documents 1 and 2 are used, there is a possibility that the degree of surface treatment will differ between the workpieces located inside the aggregate and the workpieces located on the outer edge of the aggregate.

[0006] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide an ultrasonic processing device and an ultrasonic processing method that, when performing surface treatment on an assembly of multiple workpieces, can more reliably propagate ultrasonic waves to the multiple workpieces, thereby achieving even more uniform surface treatment.

[0007] In order to solve the above problems, the inventors conducted extensive research and came up with the idea of ​​providing a reflective member that reflects ultrasonic waves inside an assembly of multiple workpieces, and bringing the reflective member into contact with some of the workpieces while maintaining an appropriate gap. Based on this idea, the inventors conducted further research and were able to find the conditions for bringing the reflective member into contact with the workpieces while maintaining an appropriate gap. The gist of the present invention, which was completed based on this finding, is as follows.

[0008] (1) An ultrasonic processing method in which a processing liquid is filled in a processing tank having a major axis with a substantially identical cross-sectional shape and provided with an ultrasonic application mechanism, and a plurality of workpieces extending in a longitudinal direction are immersed in the processing liquid, and ultrasonic waves are applied to the workpieces to perform surface processing, wherein each of the workpieces is arranged so as to be in contact with one or more other workpieces at at least two points, and one or more hollow reflecting vibrators extending in the longitudinal direction are arranged in the processing tank while immersed in the processing liquid, and each of the reflecting vibrators is arranged so as to be in contact with the other workpieces at at least two points, and when the maximum value of the outer diameter in a cross section perpendicular to the longitudinal direction of the workpieces is Ds and the maximum value of the outer diameter in a cross section perpendicular to the longitudinal direction of the reflecting vibrator is Dr, an outer diameter ratio Dr / Ds is 0.2 to 6.0, and the specific acoustic impedance Zr of the reflecting vibrator is 1×10 ７ ~2 x 10 ８ kg m －２ ・sec －１ (2) The hollow portion of the reflecting vibrator is filled with a liquid or gas having a specific acoustic impedance Zi different from the specific acoustic impedance Zr. －３(3) The ultrasonic processing method according to (2), wherein the processing liquid is filled with a gas satisfying the following formula: (1) (3) The ultrasonic processing method according to (2), wherein the thickness tr of the reflecting vibrator is 0.2 to 3.0 mm. (4) The ultrasonic processing method according to (1), wherein the processing liquid has a dissolved gas amount of 80% or more of the saturated dissolved gas amount, and the hollow part of the reflecting vibrator is filled with a liquid having a dissolved gas amount of less than 50% of the saturated dissolved gas amount. (5) The ultrasonic processing method according to (1), wherein the hollow part of the reflecting vibrator is filled with the processing liquid. (6) The ultrasonic processing method according to (4) or (5), wherein the thickness tr of the reflecting vibrator is 3.0 to 20.0 mm. (7) The ultrasonic processing method according to any one of (1) to (6), wherein the length ratio Lr / Ls of the object to be processed satisfies the relationship 0.7≦Lr / Ls≦3.0, where Ls is the length of the object in the longitudinal direction and Lr is the length of the reflecting vibrator in the longitudinal direction. (8) The ultrasonic processing method according to any one of (1) to (7), wherein a flange portion is provided on the outer surface of the reflecting vibrator. (9) The ultrasonic processing method according to (8), wherein Df is the cross-sectional size of the reflecting vibrator at the portion where the flange portion is provided, and Df / Dr is the cross-sectional size ratio satisfying the relationship 1.1≦Df / Dr≦3.0. (10) The ultrasonic processing method according to (8) or (9), wherein the flange portion has a transverse elastic modulus G of 15 to 250 GPa. (11) The ultrasonic processing method according to any one of (8) to (10), wherein the thickness tf of the flange portion is 2.0 to 10.0 times the thickness tr of the reflecting vibrator. (12) The ultrasonic processing method according to any one of (8) to (11), wherein the flange portion is provided so as to come into contact with the workpiece at least at one point along the longitudinal direction of the workpiece within a range of 5 m of the length of the workpiece.(13) An ultrasonic processing apparatus comprising: a processing tank having a longitudinal axis with approximately the same cross-sectional shape, in which a plurality of workpieces extending in the longitudinal direction and a processing liquid for immersing the workpieces are accommodated; and an ultrasonic application mechanism for applying ultrasonic waves to the processing liquid, wherein each of the workpieces is arranged so as to be in contact with one or more other workpieces at at least two points; one or more hollow reflecting vibrators extending in the longitudinal direction are arranged in the processing tank while immersed in the processing liquid, and each of the reflecting vibrators is arranged so as to be in contact with the other workpieces at at least two points; when the maximum value of the outer diameter in a cross section perpendicular to the longitudinal direction of the workpieces is Ds and the maximum value of the outer diameter in a cross section perpendicular to the longitudinal direction of the reflecting vibrator is Dr, the outer diameter ratio Dr / Ds is 0.2 to 6.0, and the specific acoustic impedance Zi of the reflecting vibrator is 1 x 10. ７ ~2 x 10 ８ kg m －２ ・sec －１ and the hollow portion of the reflecting vibrator is filled with a liquid or gas having a specific acoustic impedance Zr different from the specific acoustic impedance Zi.

[0009] As described above, according to the present invention, when performing surface treatment on an assembly of multiple workpieces, ultrasonic waves can be propagated more reliably to the multiple workpieces, thereby making the surface treatment even more uniform.

[0010] FIG. 1 is an explanatory diagram schematically showing an example of the overall configuration of an ultrasonic processing device according to an embodiment of the present invention. FIG. 1 is an explanatory diagram schematically showing an example of the overall configuration of an ultrasonic processing device according to the same embodiment. FIG. 2 is an explanatory diagram for explaining an ultrasonic application mechanism in the ultrasonic processing device according to the same embodiment. FIG. 3 is an explanatory diagram for explaining an ultrasonic application mechanism in the ultrasonic processing device according to the same embodiment. FIG. 4 is a schematic diagram for explaining a reflecting vibrator according to the same embodiment. FIG. 5 is a schematic diagram for explaining a reflecting vibrator according to the same embodiment. FIG. 6 is a schematic diagram for explaining a reflecting vibrator according to the same embodiment. FIG. 7 is a schematic diagram for explaining a reflecting vibrator according to the same embodiment. FIG. 8 is an explanatory diagram showing a state in which ultrasonic processing is performed in Experimental Example 1. FIG. 9 is an explanatory diagram showing a state in which ultrasonic processing is performed in Experimental Example 1.

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0012] <Overall Configuration of Ultrasonic Processing Apparatus> First, the overall configuration of an ultrasonic processing apparatus used in an ultrasonic processing method according to an embodiment of the present invention will be briefly described with reference to Figures 1A and 1B. Figures 1A and 1B are explanatory diagrams that schematically show an example of the overall configuration of an ultrasonic processing apparatus according to this embodiment. Note that the size of each component in the diagram has been appropriately exaggerated to facilitate explanation, and does not represent the actual dimensions or ratios between components.

[0013] The ultrasonic processing apparatus 1 according to the present embodiment is an apparatus that uses ultrasonic waves in addition to a processing solution for performing a predetermined treatment on the surfaces (portions in contact with the processing solution) of a plurality of workpieces. The ultrasonic processing apparatus 1 can be used to perform various treatments, such as cleaning, on workpieces, including various metal bodies, such as steel, and various non-metal bodies, such as plastic resin components. For example, by using the ultrasonic processing apparatus 1 according to the present embodiment to treat various metal bodies extending in a predetermined longitudinal direction, such as steel pipes, structural steel, steel bars, and steel wire, these metal bodies can be subjected to pickling, degreasing, and even cleaning. The ultrasonic processing apparatus 1 according to the present embodiment can also be used to perform a water washing process after pickling.

[0014] Here, pickling refers to a process using an acidic solution to remove oxide scale formed on the surface of a metal body by heat treatment, thermal processing, or the like. Degreasing refers to a process using an organic solvent, an aqueous solution containing a surfactant, or an alkaline degreasing solution to remove oils such as lubricants and processing oils used in processing, etc. These pickling and degreasing processes are pretreatments performed on metal bodies prior to surface finishing treatments (metal coating, chemical conversion coating, painting, etc.). Pickling may also dissolve a portion of the base metal. Pickling is also used to dissolve metal bodies by etching to improve surface finish quality. In some cases, degreasing is performed prior to pickling, and the degreasing performance of the degreasing process may affect the scale removal in the subsequent pickling process. Furthermore, degreasing is also used to improve wettability, which is an oil content control index for the finish quality of the final product.

[0015] Furthermore, the ultrasonic processing device 1 according to this embodiment, which will be described in detail below, can be used not only for the cleaning process in the manufacturing line as described above, but also for cleaning used pipes and pipes that require regular or irregular removal of dirt.

[0016] As described above, the ultrasonic processing device 1 used in the ultrasonic processing method according to this embodiment can be applied to various surface treatments of workpieces such as elongated bodies extending along a predetermined longitudinal direction, and can also be used as a workpiece to be treated. Furthermore, in addition to the various intentionally formed films described above, the ultrasonic processing device 1 according to this embodiment can also be used to treat elongated bodies to which unintentional surface deposits such as oxide scale or oil are attached in the form of a film.

[0017] The following detailed description will be given of an example in which a processing tank containing a processing solution is provided, and a group of multiple elongated bodies is immersed inside the processing tank. In this case, the group of multiple elongated bodies is immersed inside the processing tank containing the processing solution by a drive mechanism (not shown) capable of vertical movement, such as a crane. The group of multiple elongated bodies may also be immersed in the processing tank in a bundled state using a wire, net, or the like (not shown).

[0018] For convenience, the following description will be provided using the coordinate systems shown in FIGS. 1A and 1B as appropriate. The ultrasonic processing apparatus 1 according to this embodiment includes a processing tank 10 that accommodates a collection of multiple elongated objects, which are examples of objects to be processed S, as illustrated in FIG. 1A , and an ultrasonic application mechanism 20. The cross-sectional shapes perpendicular to the longitudinal axis (y-axis direction) of the processing tank 10 are substantially the same. As illustrated schematically in FIG. 1A , each object to be processed S is a tubular object such as a steel pipe or a long object such as a steel bar extending along the y-axis direction, and is arranged so as to contact one or more other objects to be processed S at at least two locations. Furthermore, the ultrasonic processing apparatus 1 according to this embodiment includes one or more reflecting vibrators 30 extending longitudinally so as to contact the object to be processed S at at least two locations, as illustrated schematically in FIG. 1B .

[0019] Note that the reflecting vibrator 30 may be located inside the assembly of the objects to be treated S, as long as it is in contact with the objects to be treated S at at least two locations, or the reflecting vibrator 30 may be exposed from the assembly of the objects to be treated S, that is, located outside the assembly S. Furthermore, when there are multiple reflecting vibrators 30, some of the reflecting vibrators 30 may be located inside the assembly and some of the reflecting vibrators 30 may be located outside the assembly.

[0020] In addition, when only one workpiece S is immersed, instead of multiple workpieces S, ultrasonic waves can be propagated to the workpiece S as long as the reflecting vibrator 30 contacts the workpiece S at at least two locations. Therefore, in this embodiment, the number of workpieces S may be one. However, when there is one workpiece S and one reflecting vibrator 30, it is not easy to contact the workpieces S at two locations, and multiple reflecting vibrators 30 are often required. For this reason, it is preferable that the number of workpieces S be two or more. The more workpieces S there are, the better, and there is no particular upper limit. The upper limit of the number of workpieces S is naturally determined by the dimensions of the treatment tank 10 and the dimensions of the workpieces S. For example, the upper limit of the number of workpieces S may be 1000 or 100.

[0021] 1A , six ultrasonic application mechanisms 20 are provided on each of the inner wall surfaces of the treatment tank 10 that are approximately parallel to the y-axis direction, and two ultrasonic application mechanisms 20 are provided on each of the inner wall surfaces that are approximately parallel to the x-axis direction. However, the number and installation state of the ultrasonic application mechanisms 20 are not limited to the example shown in FIG. 1A . The number of ultrasonic application mechanisms 20 may be appropriately set depending on the shape, size, etc. of the treatment tank 10. Furthermore, various arrangement methods for the ultrasonic application mechanisms 20 can be applied depending on the shape, size, etc. of the treatment tank 10, such as installing them as symmetrically as possible or in a staggered arrangement.

[0022] 1B illustrates a case where only one reflecting vibrator 30 is provided, but there is no particular limitation on the number of reflecting vibrators 30 used. The number of reflecting vibrators 30 may be set appropriately depending on the number of workpieces S, and two or more reflecting vibrators 30 may be used.

[0023] Each component of the ultrasonic processing device 1 used in the ultrasonic processing method according to this embodiment will be described in more detail below.

[0024] <Treatment Tank 10> The treatment tank 10 has a longitudinal axis (y-axis in the case of FIG. 1A ) with a substantially uniform cross-sectional shape. It accommodates the treatment liquid 3 used to perform a predetermined treatment on the workpiece S, the workpiece S itself, and the reflecting vibrator 30. Thus, the workpiece S accommodated in the treatment tank 10 is immersed in the treatment liquid 3. The type of treatment liquid 3 held in the treatment tank 10 is not particularly limited, and various treatment liquids can be used depending on the treatment to be performed on the workpiece S. Examples of such treatment liquids 3 include pure water, distilled water, aqueous solutions containing various compounds, and various organic solvents. These treatment liquids may contain various substances and impurities removed from the workpiece S in various forms. The treatment liquid 3 may or may not be degassed to improve the ultrasonic wave propagation efficiency. Fine bubbles, which are microscopic bubbles with a diameter of 100 μm or less, may also be present in the treatment liquid 3. The presence of fine bubbles in the treatment liquid 3 increases the ultrasonic shock waves and further improves the treatment efficiency. The temperature of the treatment liquid 3 depends on the specific treatment carried out using the treatment liquid 3, but is preferably, for example, about 20°C to 85°C.

[0025] Here, "a liquid is degassed" means that the amount of dissolved gas in the liquid in question is less than 50% of the saturated dissolved gas amount determined by the temperature of the liquid, and "a liquid is not degassed" means that the amount of dissolved gas in the liquid in question is 80% or more of the saturated dissolved gas amount.

[0026] The material used to form the treatment tank 10 according to this embodiment is not particularly limited, and may be various metal materials such as iron, steel, stainless steel plate, etc., various plastic resins such as fiber reinforced plastic (FRP) and polypropylene (PP), etc., or various bricks such as acid-resistant bricks, etc. In other words, as the treatment tank 10 constituting the ultrasonic treatment apparatus 1 according to this embodiment, it is possible to prepare a new treatment tank made of the above-mentioned material, or it is also possible to use an existing treatment tank in various production lines, etc.

[0027] Furthermore, the size of the treatment tank 10 is not particularly limited, and even large treatment tanks of various shapes, such as a liquid surface depth of approximately 1 to 2 m and a total length of approximately 3 to 25 m, can be used as the treatment tank 10 of the ultrasonic treatment device 1 of this embodiment.

[0028] <Ultrasonic Wave Application Mechanism 20> The ultrasonic wave application mechanism 20 is provided in the treatment tank 10 and applies ultrasonic waves of a predetermined frequency to the treatment liquid 3, the workpiece S, and the reflecting vibrator 30 contained in the treatment tank 10. The ultrasonic wave application mechanism 20 is not particularly limited, and various known mechanisms, such as an ultrasonic vibrator connected to an ultrasonic oscillator, can be used. Although FIGS. 1A and 1B illustrate the ultrasonic wave application mechanism 20 being provided on the wall surface of the treatment tank 10, the installation position of the ultrasonic wave application mechanism 20 on the treatment tank 10 is not particularly limited, and one or more ultrasonic vibrators may be appropriately installed on the wall surface or bottom surface of the treatment tank 10. Note that, under conditions where ultrasonic waves are uniformly propagated throughout the treatment tank 10, the oscillation loads of the individual ultrasonic vibrators are balanced uniformly, and therefore, even if there are multiple ultrasonic vibrators, interference between the generated ultrasonic waves does not occur.

[0029] 2A and 2B are explanatory diagrams that schematically show an example of the configuration of the ultrasonic wave application mechanism 20 according to this embodiment.

[0030] 2A , the ultrasonic application mechanism 20 according to this embodiment may be configured, for example, with an ultrasonic oscillator 201 and an ultrasonic vibrator 203. The ultrasonic oscillator 201 is a device that supplies power to the ultrasonic vibrator 203 at a desired output. The ultrasonic vibrator 203 converts the power output from the ultrasonic oscillator 201 into vibrations, and emits ultrasonic waves of a desired frequency from its oscillation surface. By installing the ultrasonic vibrator 203 portion of the ultrasonic application mechanism 20 relative to the processing tank 10, it becomes possible to emit ultrasonic waves relative to the planned liquid level line of the processing liquid 3.

[0031] 2B , the ultrasonic application mechanism 20 according to the present embodiment may be configured, for example, with an ultrasonic oscillator 201 and a throw-in type vibrator 211. As shown in FIG. 2B , the throw-in type vibrator 211 is configured by arranging a plurality of ultrasonic vibrators 203 inside a housing 205, and then sealing the housing 205 with a member made of a predetermined material that transmits ultrasonic waves so as to cover the oscillation surface of each ultrasonic vibrator 203. In this case, the member provided so as to cover the oscillation surface of each ultrasonic vibrator 203 becomes the oscillation surface of the throw-in type vibrator 211. In the case of the throw-in type vibrator 211, the spacing and number of the ultrasonic vibrators 203 and the size of the oscillation surface are determined in consideration of the output stability and oscillation efficiency of the ultrasonic waves.

[0032] The frequency of the ultrasonic waves output from the ultrasonic application mechanism 20 is preferably, for example, 20 kHz to 200 kHz. If the frequency of the ultrasonic waves is less than 20 kHz, the propagation of the ultrasonic waves may be hindered by large bubbles generated from the surface of the workpiece S, and the effect of the ultrasonic waves in improving the processability may be reduced. The frequency of the ultrasonic waves output from the ultrasonic application mechanism 20 is more preferably 20 kHz or higher, and even more preferably 25 kHz or higher. On the other hand, if the frequency of the ultrasonic waves exceeds 200 kHz, the ultrasonic waves may propagate too linearly when processing the workpiece S, which may reduce the uniformity of the process. The frequency of the ultrasonic waves output from the ultrasonic application mechanism 20 is more preferably 150 kHz or lower, and even more preferably 100 kHz or lower.

[0033] It is preferable to select an appropriate frequency of the ultrasonic waves to be applied within the above range depending on the type of workpiece S, etc., and depending on the type of workpiece S, ultrasonic waves of two or more frequencies may be applied.

[0034] Furthermore, the ultrasonic wave application mechanism 20 may have a frequency sweep function that can apply ultrasonic waves while sweeping the frequency within a predetermined range centered on a selected ultrasonic frequency. Such a frequency sweep function makes it possible to achieve the following additional effects.

[0035] A general property of ultrasonic waves is that the transmittance of the ultrasonic waves passing through an irradiated object is maximized when the wavelength of the ultrasonic waves is ¼ of the wavelength corresponding to the thickness of the irradiated object. Therefore, by applying ultrasonic waves while sweeping the frequency within an appropriate range, for example, when the object S to be treated has a hollow portion such as a tubular body, it is possible to increase the amount of ultrasonic waves that pass into the tubular body, and it is possible to further improve the processing efficiency of the ultrasonic processing device 1 according to this embodiment.

[0036] <Reflecting Vibrator 30> The reflecting vibrator 30 according to this embodiment is immersed in the treatment liquid 3, for example, as shown in FIG. 1B , and is provided inside or outside the collection of multiple workpieces S immersed in the treatment liquid 3. Here, "inside the collection of workpieces S" does not only mean a state in which the reflecting vibrator 30 is entirely surrounded by the collection of workpieces S, but also includes a state in which at least a portion of the reflecting vibrator 30 is in contact with at least two workpieces S and is surrounded by the workpieces S. In other words, it is sufficient that at least a portion of the reflecting vibrator 30 is buried inside the collection of multiple workpieces S. Furthermore, the reflecting vibrator 30 may be located outside the collection of workpieces S, as long as it is in contact with other workpieces S at at least two locations.

[0037] The reflecting vibrator 30 is a hollow member extending in the longitudinal direction, and in the example shown in Fig. 1B, the reflecting vibrator 30 extends in the y-axis direction. The reflecting vibrator 30 is formed using a material that can reflect applied ultrasonic waves.

[0038] The reflecting vibrator 30 according to this embodiment will be described in detail below with reference to Figures 3 to 7. Figures 3 to 7 are schematic diagrams for explaining the reflecting vibrator 30 according to this embodiment.

[0039] 3, when ultrasonic waves, which are longitudinal waves, reach the surface of the reflecting vibrator 30 according to this embodiment, the ultrasonic waves are reflected by the surface of the reflecting vibrator 30. Therefore, by using the reflecting vibrator 30 according to this embodiment, ultrasonic waves that have reached the inside of an assembly of multiple workpieces S can be reflected, making it possible to apply ultrasonic waves to a larger number of workpieces S. As a result, with the ultrasonic processing apparatus 1 according to this embodiment, ultrasonic waves can be more reliably propagated to multiple workpieces S, making it possible to achieve even more uniform surface treatment.

[0040] Furthermore, when the ultrasonic waves, which are longitudinal waves, reach the surface of the reflecting vibrator 30, the reflecting vibrator 30 generates transverse waves, as shown schematically in FIG. 3 . As previously exemplified, the frequency of the ultrasonic waves applied in the ultrasonic processing device 1 according to this embodiment is, for example, in the kHz range, but the frequency of the transverse waves generated by the reflecting vibrator 30 is lower than the frequency of the ultrasonic waves, for example, on the order of several tens to several hundreds of Hz. The generated transverse waves propagate through the reflecting vibrator 30, but they also propagate to the workpiece S through the contact portion of the workpiece S. Furthermore, the transverse waves propagating through the workpiece S propagate to other workpieces S through the contact portion with other workpieces S. Due to this propagation of transverse waves, the ultrasonic processing device 1 according to this embodiment can vibrate the workpiece S using transverse waves in addition to ultrasonic cavitation. As a result, the ultrasonic processing device 1 according to this embodiment can more reliably perform various surface treatments on the workpiece S.

[0041] Here, in order to reliably reflect the ultrasonic waves that reach the reflecting vibrator 30, the reflecting vibrator 30 has a specific acoustic impedance Zr of 1×10 ７ kg m －２ ・sec －１ ~2 x 10 ８ kg m －２ ・sec －１The reflecting vibrator 30 is formed from a material having a specific acoustic impedance Zr within the above range. By forming the reflecting vibrator 30 from a material having the above-mentioned specific acoustic impedance Zr, the reflecting vibrator 30 can reliably reflect ultrasonic waves. Furthermore, by forming the reflecting vibrator 30 from a material having the above-mentioned specific acoustic impedance Zr, the hollow portion of the reflecting vibrator 30 is filled with a liquid or gas having a specific acoustic impedance Zi different from the specific acoustic impedance Zr, as will be described below.

[0042] Specific acoustic impedance is 1 x 10 ７ kg m －２ ・sec －１ ~2 x 10 ８ kg m －２ ・sec －１ Examples of materials with a specific acoustic impedance of 0.01% include various metals or metal oxides, and various ceramics including non-oxide ceramics. Specific examples of such materials include steel (with a specific acoustic impedance [unit: kg m －２ ・sec －１ ]: 4.70 x 10 ７ , below, the values ​​in parentheses similarly represent the values ​​of specific acoustic impedance.), iron (3.78×10 ７ ), nickel chromium steel (3.98 x 10 ７ ), stainless steel (SUS, 4.57 x 10 ７ ), titanium (2.73 x 10 ７ ), zinc (3.00 x 10 ７ ), Nickel (5.35 x 10 ７ ), aluminum (1.73 x 10 ７ ), brass (4.06 x 10 ７ ), duralumin (1.71 x 10 ７ ), tungsten (1.03 × 10 ８ ), glass (1.32 x 10 ７ ), quartz glass (1.27 × 10 ７ ), glass lining (1.67 x 10 ７ ), alumina (aluminum oxide, 3.84 × 10 ７ ), zirconia (zirconium oxide, 3.91 × 10 ７ ), silicon nitride (SiN, 3.15 × 10７ ), silicon carbide (SiC, 3.92 × 10 ７ ), tungsten carbide (WC, 9.18 × 10 ７ In the reflecting vibrator 30 according to this embodiment, the material used to form the reflecting vibrator 30 may be appropriately selected depending on the properties of the processing liquid 3 held in the processing tank 10, the strength required for the reflecting vibrator 30, etc., but it is preferable to use various metals or metal oxides having the specific acoustic impedance as described above.

[0043] The cross-sectional shape of the reflecting vibrator 30 (more specifically, the shape of the cross section perpendicular to the longitudinal direction of the reflecting vibrator 30) may be circular, elliptical, or polygonal, as shown in Fig. 4. However, the closer the cross-sectional shape is to a circular shape, the less anisotropy occurs in the direction of travel of the reflected wave, and the easier it is to contact the workpiece S, so it is preferable that the cross-sectional shape of the reflecting vibrator 30 is circular.

[0044] Here, the ultrasonic waves propagate through the processing liquid 3, which is the medium. Therefore, it is important that there is a gap around the reflecting vibrator 30 in order to ensure that the ultrasonic waves reach the surrounding workpiece S. On the other hand, in order to propagate the transverse waves shown in FIG. 3 to the workpiece S, it is important that at least a portion of the reflecting vibrator 30 and at least a portion of the workpiece S are in contact with each other. The inventors have thoroughly investigated the conditions for creating a gap between the reflecting vibrator 30 and the workpiece S while also achieving a contact state, and have found a condition that the cross-sectional size of the reflecting vibrator 30 must satisfy, based on the cross-sectional size of the workpiece S. Such conditions will be described below.

[0045] Focus is placed on the cross-sectional shape of the reflecting vibrator 30 (more specifically, the shape of a cross section perpendicular to the longitudinal direction) as shown in Fig. 4. Here, the maximum value of the diameter is taken as the maximum value of the diameter when the cross-sectional shape is circular as shown in the upper left of Fig. 4; the maximum value of the major axis is taken as the maximum value of the diameter when the cross-sectional shape is elliptical as shown in the upper right of Fig. 4; and the size of the longest diagonal when the cross-sectional shape is polygonal as shown in the lower left of Fig. 4. Similarly to the reflecting vibrator 30, the maximum value of the outer diameter of the workpiece S is taken as Ds. Here, when a flange portion 33 is provided on the reflecting vibrator as described below, the maximum value of the outer diameter of the portion excluding the flange portion 33 is taken as Dr.

[0046] In this case, in the ultrasonic processing device 1 according to this embodiment, the outer diameter ratio Dr / Ds of the reflecting vibrator 30 satisfies the relationship 0.2≦Dr / Ds≦6.0. When the outer diameter ratio Dr / Ds is within the above range, the reflecting vibrator 30 can create a gap between itself and the workpiece S while also achieving a contact state.

[0047] If the outer diameter ratio Dr / Ds of the reflecting vibrator 30 is less than 0.2, the gap between the reflecting vibrator 30 and the workpiece S becomes too narrow, making it impossible to propagate longitudinal waves of ultrasonic waves through the processing liquid 3, and making it impossible to apply ultrasonic waves to the workpiece S. The outer diameter ratio Dr / Ds of the reflecting vibrator 30 is preferably 0.5 or more, and more preferably 1.0 or more. By setting the outer diameter ratio Dr / Ds of the reflecting vibrator 30 within the above-mentioned preferred range, it becomes possible to more reliably create a gap between the reflecting vibrator 30 and the workpiece S while also achieving a contact state.

[0048] On the other hand, if the outer diameter ratio Dr / Ds of the reflecting vibrator 30 exceeds 6.0, the reflecting vibrator 30 becomes relatively too large, and there are cases in which it is not possible to secure enough space to process multiple workpieces S, or even if contact with the workpieces S can be maintained, ultrasonic waves cannot propagate because they are hidden by the reflecting vibrator 30. The outer diameter ratio Dr / Ds of the reflecting vibrator 30 is preferably 5.0 or less, and more preferably 4.5 or less. By setting the outer diameter ratio Dr / Ds of the reflecting vibrator 30 within the above-mentioned preferred range, it is possible to more reliably create a gap between the reflecting vibrator 30 and the workpieces S while also achieving a contact state.

[0049] 4, the thickness (wall thickness) of the reflecting vibrator 30 is represented as tr, the specific acoustic impedance of the reflecting vibrator 30 is represented as Zr, and the specific acoustic impedance of the substance inside the reflecting vibrator 30 (liquid or gas present inside the reflecting vibrator regardless of whether it is enclosed or not) is represented as Zi. In this case, in this embodiment, the ratio of the specific acoustic impedances Zi / Zr is 1×10 －３ If the ratio Zi / Zr of the specific acoustic impedance is 1×10 or less, it is preferable that the thickness t [mm] of the reflecting vibrator 30 is set to be in the range of 0.2≦t≦3.0. －３ If the thickness tr of the reflecting vibrator 30 exceeds 3.0 mm, it is preferable to set the thickness tr of the reflecting vibrator 30 within the range of 3.0 mm<t≦20.0 mm.

[0050] Here, the ratio of the specific acoustic impedances Zi / Zr is 1×10 －３ or less means that the difference between the specific acoustic impedance Zi of the material inside the hollow of the reflecting vibrator 30 and the specific acoustic impedance Zr of the reflecting vibrator 30 is large, and the ultrasonic waves are likely to be reflected at the interface between the reflecting vibrator 30 and the material inside the hollow of the reflecting vibrator 30. Furthermore, when the specific acoustic impedance Zr of the reflecting vibrator 30 is within the above range, examples of materials that can realize such a specific acoustic impedance ratio Zi / Zr include various gases (e.g., air, oxygen, nitrogen, carbon dioxide, inert gases such as helium and argon, etc.). For example, the specific acoustic impedance of air is 4.29×10 ２ kg m －２ ・sec－１ is.

[0051] In this case, by setting the thickness tr of the reflecting vibrator 30 to 0.2 mm to 3.0 mm, the time it takes for the ultrasonic waves to pass through the reflecting vibrator 30 can be shortened, and furthermore, the ultrasonic waves that have passed through and reached the inner surface of the reflecting vibrator 30 can be more efficiently reflected by the sealed gas filled in the hollow interior of the reflecting vibrator 30. If the thickness tr of the reflecting vibrator 30 is thinner than 0.2 mm, the strength of the reflecting vibrator 30 when placed inside an assembly of multiple workpieces may be weak, and the reflecting vibrator 30 may be deformed and unable to fulfill its role as the reflecting vibrator 30. When the ratio Zi / Zr of the specific acoustic impedance is 1×10 －３ When the thickness tr of the reflecting vibrator 30 is less than 3.0 mm, the thickness tr of the reflecting vibrator 30 is more preferably 0.3 mm or more. On the other hand, when the thickness tr of the reflecting vibrator 30 is greater than 3.0 mm, the ultrasonic waves are absorbed or scattered within the reflecting vibrator 30 or are reflected at the surface of the reflecting vibrator 30 before reaching the interface inside the hollow interior of the reflecting vibrator 30, resulting in attenuation of the ultrasonic waves and inefficient reflection. When the ratio of the specific acoustic impedance Zi / Zr is 1×10 －３ If the thickness t of the reflecting vibrator 30 is less than or equal to 2.0 mm, it is more preferable that the thickness t of the reflecting vibrator 30 is less than or equal to 2.0 mm.

[0052] On the other hand, the ratio of specific acoustic impedance Zi / Zr is 1×10 －３ That the specific acoustic impedance Zi / Zr is greater than 1.0×10 means that the difference between the specific acoustic impedance Zi of the material inside the hollow of the reflecting vibrator 30 and the specific acoustic impedance Zr of the reflecting vibrator 30 is small, and ultrasonic waves are easily transmitted when propagating inside the hollow of the reflecting vibrator 30. In addition, when the specific acoustic impedance Zr of the reflecting vibrator 30 is within the above range, examples of materials that can realize such a specific acoustic impedance ratio Zi / Zr include silicone rubber (specific acoustic impedance: 1.0×10 ６ kg m －２ ・sec －１ In addition to various solids such as resins such as cellulose acetate, etc., various liquids such as pure water, distilled water, aqueous solutions containing various compounds, and various organic solvents can be used.

[0053] In addition, the ratio of the specific acoustic impedance Zi / Zr is 1×10－３ When the specific acoustic impedance ratio Zi / Zr is greater than 1×10, and the treatment liquid 3 is a non-degassed liquid, the hollow portion of the reflecting vibrator 30 may be filled with a deegassed liquid and sealed. By sealing the deegassed liquid in this way, it is possible to further improve the ultrasonic wave propagation efficiency and further improve the treatment performance of the surface treatment. In addition, when the specific acoustic impedance ratio Zi / Zr is 1×10, the hollow portion of the reflecting vibrator 30 may be filled with a deegassed liquid and sealed. －３ When the specific acoustic impedance ratio Zi / Zr is greater than 1 / 2, the hollow portion of the processing liquid 3 may be filled with the processing liquid 3 itself. In order to fill the hollow portion of the processing liquid 3 with the processing liquid 3, partitions or the like for sealing the processing liquid 3 may be provided near both ends of the reflecting vibrator 30, but partitions or the like may not be provided. Note that, regardless of the magnitude of the ratio Zi / Zr of the specific acoustic impedances, when the hollow portion of the reflecting vibrator 30 is filled with a substance different from the processing liquid 3, partitions or the like for sealing the substance are provided near both ends of the reflecting vibrator 30.

[0054] The specific acoustic impedance ratio Zi / Zr is 1 x 10 －３ When the thickness tr of the reflecting vibrator 30 is greater than 3.0 mm, by setting the thickness tr of the reflecting vibrator 30 to 3.0 mm to 20.0 mm, it becomes possible to make it difficult for the ultrasonic waves that have reached the surface of the reflecting vibrator 30 to penetrate into the reflecting vibrator 30, and to more efficiently reflect them from the surface of the reflecting vibrator 30. When the thickness tr of the reflecting vibrator 30 is thinner than 3.0 mm, the ultrasonic waves pass through the reflecting vibrator 30, reducing the reflectivity at the surface, and as a result, the propagation of the ultrasonic waves to the workpiece is reduced. When the ratio Zi / Za of the specific acoustic impedance is 1×10 －３ When the thickness tr of the reflecting vibrator 30 is greater than 20.0 mm, the thickness tr of the reflecting vibrator 30 is more preferably 5.0 mm or more. On the other hand, when the thickness tr of the reflecting vibrator 30 is greater than 20.0 mm, the relationship between reflection and transmission depending on the wavelength of the ultrasonic frequency becomes significant, making it difficult to control the reflection on the surface of the reflecting vibrator 30. When the ratio Zi / Za of the specific acoustic impedance is 1×10 －３ When the thickness tr of the reflecting vibrator 30 is more than 20.0 mm, the thickness tr is more preferably 20.0 mm or less.

[0055] The longitudinal length of the workpiece S (e.g., the length in the y-axis direction shown in FIG. 5 ) is represented by Ls, and the longitudinal length of the reflecting vibrator 30 (e.g., the length in the y-axis direction shown in FIG. 5 ) is represented by Lr. In this case, when multiple workpieces S are arranged in the longitudinal direction, the following formula is satisfied for each length of the multiple workpieces S. In this case, in the reflecting vibrator 30 according to this embodiment, the length ratio Lr / Ls preferably satisfies the relationship 0.7≦Lr / Ls≦3.0. If the length ratio Lr / Ls is less than 0.7, a large portion will be out of contact with the workpiece S, and the reflection effect may not be obtained. The length ratio Lr / Ls is more preferably 0.7 or greater, even more preferably 0.8 or greater, and even more preferably 0.9 or greater. On the other hand, if the length ratio Lr / Ls is greater than 3.0, the reflection efficiency will increase in areas where there are no workpieces S, which may lead to vibrator failure. By setting the ratio Lr / Ls of the longitudinal lengths of the reflecting vibrator 30 and the workpiece S within the above range, it becomes possible to more reliably create a gap between the reflecting vibrator 30 and the workpiece S while also achieving a contact state. The ratio Lr / Ls of the longitudinal lengths of the reflecting vibrator 30 and the workpiece S is more preferably 2.0 or less, and even more preferably 1.5 or less.

[0056] 5 illustrates the reflecting vibrator 30 according to this embodiment as a single member without any seams, but the reflecting vibrator 30 according to this embodiment may have a structure in which multiple members are connected. The method for connecting and integrating the multiple members is not particularly limited, and the multiple members may be connected by welding or by using various connecting members such as nuts and bolts. The reflecting vibrator 30 is hollow, but partitions or the like may be provided near both ends of the reflecting vibrator 30. In particular, partitions or the like near both ends of the reflecting vibrator 30 are essential to fill the interior of the reflecting vibrator 30 with a substance having a specific acoustic impedance different from that of the treatment liquid 3.

[0057] In this embodiment, the end of the reflecting vibrator 30 may not be sealed, and the hollow portion of the reflecting vibrator 30 immersed in the treatment liquid 3 may be filled with the treatment liquid 3. Alternatively, the hollow portion of the reflecting vibrator 30 may be sealed and not filled with the treatment liquid 3. In this case, the sealed hollow portion of the reflecting vibrator 30 is filled with a gas (e.g., air, an inert gas, etc.) or a liquid. The reflecting vibrator 30 having such a sealed hollow structure can more reliably reflect ultrasonic waves that reach the reflecting vibrator 30. Furthermore, when the inside of the reflecting vibrator 30 is filled with gas (i.e., when the gas is sealed), it is more preferable that the sealed hollow portion of the reflecting vibrator 30 be in a reduced pressure state of approximately -100 kPa to -10 kPa below atmospheric pressure. The sealed hollow portion of the reflecting vibrator 30 in the reduced pressure state described above can more reliably reflect ultrasonic waves that reach the reflecting vibrator 30.

[0058] 6, the reflecting vibrator 30 according to this embodiment is preferably provided with a flange portion 33 on its outer surface. By providing such a flange portion 33, it becomes possible to more efficiently propagate transverse waves generated in the reflecting vibrator 30 by ultrasonic waves to the workpiece S. When the flange portion 33 is provided on the reflecting vibrator 30, the maximum outer diameter Dr described above is the maximum outer diameter of the portion other than the flange portion 33.

[0059] The flange portion 33 is preferably integrated with the reflecting vibrator 30. The means for integrating the flange portion 33 with the reflecting vibrator 30 is not particularly limited. For example, the flange portion 33 may be integrated with the reflecting vibrator 30 by welding, or may be integrated with the reflecting vibrator 30 by various connecting members such as bolts and nuts. Furthermore, the flange portion 33 may be formed to protrude from the reflecting vibrator 30 by bulging molding, or the flange portion 33 may be formed by machining the reflecting vibrator 30.

[0060] 7, the size of the cross section (cross section perpendicular to the y-axis direction) of the reflecting vibrator 30 where the flange portion 33 is provided is represented by Df, and the maximum outer diameter of the reflecting vibrator 30 where the flange portion 33 is not provided is represented by Dr. In this case, the cross-sectional size ratio Df / Dr preferably satisfies the relationship 1.1≦Df / Dr≦3.0. When the cross-sectional size ratio Df / Dr satisfies the above relationship, it becomes possible to propagate the transverse waves generated in the reflecting vibrator 30 to the workpiece S while suppressing attenuation of the strength. The cross-sectional size ratio Df / Dr is more preferably 1.2 or more or 1.4 or more and 2.0 or less or 1.6 or less.

[0061] Furthermore, it is preferable that the thickness of the flange portion 33 (thickness tf of the flange portion 33 in the y-axis direction shown in FIG. 5) is the same as or greater than the thickness tr of the reflecting vibrator 30. This makes it possible to more reliably propagate the transverse waves generated in the reflecting vibrator 30 to the workpiece S while suppressing attenuation of the strength. The thickness tf of the flange portion 33 is more preferably 2 to 10 times the thickness tr of the reflecting vibrator 30.

[0062] 6 illustrates a case where three flange portions 33 are provided on the reflecting vibrator 30, but the number of flange portions 33 provided on one reflecting vibrator 30 is not particularly limited and may be one or two, or may be four or more. The separation distance between adjacent flange portions 33 (separation distance p in FIG. 6) is also not particularly limited and may be set appropriately depending on the length of the reflecting vibrator 30 in the y-axis direction, but is preferably about 0.1 m to 5.0 m, for example.

[0063] The flange portion 33 is preferably formed using a material with a transverse elastic modulus G in the range of 15 to 250 GPa. The transverse elastic modulus (also known as the shear elastic modulus) G can be considered an index of resistance to deformation. The propagation state of transverse waves generated in the reflecting vibrator 30 by ultrasonic waves depends on the transverse elastic modulus, and the more easily the material deforms, the more the transverse waves attenuate. Transverse waves propagate in a direction perpendicular to the propagation direction of the ultrasonic waves (compression waves), causing vertical displacement and propagating the transverse wave vibrations through the solid reflecting vibrator 30. To ensure the propagation of such transverse waves, it is preferable that the transverse elastic modulus G of the material forming the flange portion 33 be large. On the other hand, if the transverse elastic modulus is too large, the difference in specific acoustic impedance with the reflecting vibrator 30 may increase, increasing the possibility of reflection at the interface between different materials, which is undesirable. From this perspective, the transverse elastic modulus G of the material forming the flange portion 33 is preferably in the range of 15 to 250 GPa. The modulus of transverse elasticity G of the material forming the flange portion 33 is more preferably 30 to 100 GPa.

[0064] Examples of materials having the above-mentioned modulus of transverse elasticity G include iron (60 GPa), stainless steel (74 GPa), titanium alloy (41 GPa), brass (37 GPa), quartz (31 GPa), magnesium alloy (17 GPa), and tungsten carbide (219 GPa).

[0065] Furthermore, if the difference in specific acoustic impedance between the flange portion 33 and the main body of the reflecting vibrator 30 becomes too large, there is a high possibility that reflection will occur at the interface between the different materials. From this perspective, the flange portion 33 is preferably formed from the same material as the reflecting vibrator 30, and more preferably, is molded integrally with the reflecting vibrator 30 by bulging or cutting.

[0066] The flange portion 33 of the reflecting vibrator 30 as described above is preferably provided so as to contact the workpiece S at at least one location at intervals of 5 m or less along the longitudinal direction of the workpiece S. By providing the reflecting vibrator 30 so as to satisfy the above-described positional relationship, ultrasonic waves can be more reliably propagated to the multiple workpieces S when performing surface treatment on an assembly of multiple workpieces S. More preferably, the flange portion 33 is provided so as to contact the workpiece S at two or more locations at intervals of 5 m or less along the longitudinal direction of the workpiece S. Furthermore, when multiple contact locations are provided, it is more preferable that the contact interval be 0.1 m or more. If the contact interval of the flange portion 33 is less than 0.1 m, the reflected ultrasonic waves may be repeatedly reflected multiple times within the closed space, resulting in attenuation at the flange portion 33.

[0067] The ultrasonic processing device 1 used in the ultrasonic processing method according to this embodiment has been described in detail above.

[0068] <Regarding the Ultrasonic Processing Method> The ultrasonic processing method according to this embodiment is realized using the ultrasonic processing device 1 described above. The ultrasonic processing method realized using the ultrasonic processing device 1 involves applying ultrasonic waves to a processing tank having a longitudinal axis with a substantially identical cross-sectional shape, filled with a processing solution, and a plurality of workpieces extending in the longitudinal direction, immersed in the processing solution. The surface of the workpieces is then processed while ultrasonic waves are applied to the workpieces. Each of the workpieces is arranged so as to contact one or more other workpieces at at least two locations. One or more hollow reflecting vibrators extending in the longitudinal direction are arranged in the processing tank while immersed in the processing solution, and each of the reflecting vibrators is arranged so as to contact the other workpieces at at least two locations. Furthermore, when the maximum outer diameter of the workpiece in a cross section perpendicular to the longitudinal direction is Ds and the maximum outer diameter of the reflecting vibrator in a cross section perpendicular to the longitudinal direction is Dr, the outer diameter ratio Dr / Ds is 0.2 to 6.0, and the specific acoustic impedance Zr of the reflecting vibrator is 1×10 ７ ~2 x 10 ８ kg m －２ ・sec －１The hollow portion of the reflecting vibrator is filled with a liquid or gas having a specific acoustic impedance Zi different from the specific acoustic impedance Zr.

[0069] Furthermore, the preferred conditions for the ultrasonic processing method according to this embodiment are as described in the description of the ultrasonic processing apparatus according to this embodiment, and detailed description thereof will be omitted below.

[0070] The ultrasonic processing method according to this embodiment has been briefly described above.

[0071] The ultrasonic treatment method and ultrasonic treatment device according to the present invention will be specifically described below with reference to examples and comparative examples. Note that the examples shown below are merely examples of the ultrasonic treatment method and ultrasonic treatment device according to the present invention, and the ultrasonic treatment method and ultrasonic treatment device according to the present invention are not limited to the examples shown below.

[0072] 8A and 8B are explanatory diagrams showing the state of ultrasonic treatment in Experimental Example 1, simulating the water washing (rinsing) of a steel pipe. The treatment tank 10 has an outer wall made of SUS, a width of 1.0 m, a length of 15.0 m, and a capacity of 9.0 m. ３ Using this treatment tank 10, verification was carried out by immersing the workpiece S (steel pipe or brass pipe) with oxide scale remaining on the inside and outside of the pipe after pickling for a predetermined period of time. The cleaning liquid functioning as the treatment liquid 3 was non-degassed water at a temperature of 20°C (specific acoustic impedance: 1.50 × 10 ６ kg m －２ ・sec －１ ) was used, and because the pickling solution was carried over, a cleaning solution with an acidic condition of pH 4 to 7 was used.

[0073] The ultrasonic oscillator of the ultrasonic application mechanism 20 had an output of 1200 W, and ten SUS throw-in type ultrasonic vibrators as shown in Figure 2B were used. The ultrasonic frequency was 35 kHz. A buffer material (not shown) was installed on the wall of the treatment tank 10 to prevent damage to the workpiece S.

[0074] The reflecting vibrator 30, which is placed in contact with the object to be treated S, was compared by changing the size, shape, length, sealed structure, and contact conditions. Here, the material used for the reflecting vibrator 30 (including the flange) was stainless steel (specific acoustic impedance Zr: 4.57×10 ７ kg m －２ / sec －１ ) Duralumin material (specific acoustic impedance Zr: 1.71 x 10 ７ kg m －２ ・sec －１ ), nickel-chromium steel (specific acoustic impedance Zr: 3.98×10 ７ kg m －２ ・sec －１ ), brass (specific acoustic impedance Zr: 4.06 × 10 ７ kg m －２ ・sec －１ ), or polyethylene (specific acoustic impedance Zr: 1.75 × 10 ７ kg m －２ ・sec －１ The flange portion 33 was made of stainless steel (modulus of transverse elasticity G: 74 GPa), quartz (G: 31 GPa), tungsten carbide (G: 219 GPa), brass (G: 37 GPa), or polystyrene (G: 1.4 GPa).

[0075] In the "Enclosed substance" column of Table 1 below, the term "degassed water" refers to water that has been deaerated. In addition, in the "Sealed or not" column of Table 1 below, the term "no" is written and the term "non-degassed water" is written in the "Enclosed substance" column, which means that there are no partitions or the like near both ends of the reflecting vibration body 30, and the inside of the reflecting vibration body 30 is filled with the treatment liquid 3 (i.e., non-degassed water).

[0076] In this experimental example, a bundle of 10 steel or brass pipes, each with an outer diameter of 50 mm and a length of 3 to 10 m, was placed in the center of the treatment tank 10 as an example of multiple objects to be treated S. A reflecting vibrator 30 was then provided so as to be in contact with the steel or brass pipes. The ultrasonic intensity and vibration acceleration were measured, and cleaning evaluation was performed according to the following criteria. Here, Lr / Ls is the ratio of the length of the reflecting vibrator to the length of the longest object to be treated S. In Comparative Example 4 described below, the steel pipes were laid flat with minimal overlap, and then the reflecting vibrator 30 was placed at the end of the bundle of steel pipes so that the reflecting vibrator 30 would contact the bundle at only one point.

[0077] Regarding ultrasonic intensity, an ultrasonic level monitor (19001D manufactured by Kaijo) was used to measure the ultrasonic intensity (mV) at one point on the workpiece S held in the treatment tank (for example, position 1 in the side view shown in Figure 8A) and at one point in the treatment tank that was not on the workpiece S (position 2 in Figure 8B), and the relative ultrasonic intensity (the relative intensity when the measurement result of Comparative Example 1, i.e., the measured ultrasonic intensity when only the steel pipe was installed without the reflecting vibrator 30, was taken as 1) was calculated, and the propagation into the workpiece S and the tank was compared.

[0078] Furthermore, a three-axis acceleration sensor (a Rorze debug scope) was used to measure the acceleration of the reflecting vibrator 30 and the workpiece S in contact with the reflecting vibrator 30. The three-axis acceleration sensor was used to measure the object to be measured by slightly raising it above the liquid surface so as not to come into contact with the liquid. In Table 1 below, "Measurement A" is the measurement result of the reflecting vibrator 30, and "Measurement B" is the measurement result of the workpiece S in contact with the reflecting vibrator 30.

[0079] In this experimental example, the removal rate of oxide scale from the inner surface of the pipe was measured, and the measured removal rate was evaluated as the water washing performance. More specifically, for each workpiece S, the area of ​​the inner surface of the pipe extending from a position 1 m from the end of the pipe to a position 5 cm inward in the axial direction of the pipe was defined as the evaluation area (evaluation area: approximately 70 cm ２) and the inner surface of the pipe was photographed before and after rinsing so that the evaluation area was included. The obtained images were binarized to obtain binarized images, from which the oxide scale removal rate was calculated. The ratio of the amount of oxide scale removed under each condition to the amount of oxide scale remaining before rinsing was taken as the oxide scale removal rate. Note that since there were two evaluation areas in one workpiece S, the average value of 2 locations x 10 pipes = 20 locations was taken as the oxide scale removal rate. The evaluation criteria for water rinsing performance are as shown below in Table 2.

[0080] Removal rate of remaining oxide scale film: A: 100% or less to 95% or more; B: Less than 95% to 90% or more; C: Less than 90% to 80% or more; D: Less than 80% to 60% or more; E: Less than 60% to 40% or more; F: Less than 40%

[0081] That is, ratings A and B indicate very good water-washing performance, rating C indicates good water-washing performance, rating D indicates some difficulty in water-washing performance, and ratings E and F indicate poor water-washing performance. Samples that received ratings A to D were considered to pass. The results are summarized in Table 1 below.

[0082]

[0083] First, looking at the comparative examples, Comparative Example 1, in which the reflecting vibrator 30 according to the present invention was not held in the treatment tank 10, and Comparative Examples 2 and 3, in which the reflecting vibrator 30 had a cross-sectional area ratio to the workpiece S of less than 0.2 or more than 6.0, showed poor water-washing performance or insufficient areas. This result is consistent with the measurement results showing that the relative ultrasonic intensity and vibration acceleration were almost unchanged from those of Comparative Example 1. This indicates that the ultrasonic reflection efficiency of the reflecting vibrator 30 of Comparative Examples 2 and 3 was not improved, and the effect of the reflecting vibrator was not fully realized. Furthermore, in Comparative Example 4, in which the reflecting vibrator 30 was brought into contact with only one steel pipe, although the vibration acceleration was propagated to the contacting steel pipe, the relative ultrasonic intensity was almost the same as that of Comparative Example 1. This indicates that the effect of the reflecting vibrator 30 was not fully realized due to the small number of contact points of the reflecting vibrator 30. Furthermore, in Comparative Example 5, in which a polyethylene reflecting vibrator was used, the vibration acceleration was not propagated to the steel pipe, and the effect of the reflecting vibrator was not fully realized.

[0084] On the other hand, it was confirmed that Examples 1 to 36, which were provided with a reflecting vibrator according to the present invention and had different shapes, cross-sectional ratios to the workpiece S, and length ratios, had good water washing performance. In particular, excellent water washing performance was confirmed in Examples 5 to 13, which had a sealed structure. Furthermore, excellent water washing performance was also confirmed in Examples 20 to 35, which were provided with flanges. A correlation was obtained between these water washing performances and the ultrasonic intensity and vibration acceleration.

[0085] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0086] REFERENCE SIGNS LIST 1 ultrasonic treatment device 3 treatment liquid 10 treatment tank 20 ultrasonic wave application mechanism 30 reflecting vibrator 33 flange portion 201 ultrasonic oscillator 203 ultrasonic vibrator 205 housing 211 throw-in type vibrator S treatment object

Claims

1. A ultrasonic treatment method for performing surface treatment on a workpiece while applying ultrasonic waves to the workpiece in a treatment tank having a major axis with a substantially identical cross-sectional shape and provided with an ultrasonic application mechanism, wherein the treatment liquid fills the treatment tank and a plurality of workpieces extending in the longitudinal direction are immersed in the treatment liquid, and each of the workpieces is arranged so as to be in contact with one or more other workpieces at at least two locations, one or more hollow reflection vibrators extending in the longitudinal direction are arranged in the treatment tank in a state of being immersed in the treatment liquid, each of the reflection vibrators is arranged so as to be in contact with other workpieces at at least two locations, when the maximum value of the outer diameter in the cross-section perpendicular to the longitudinal direction of the workpiece is Ds and the maximum value of the outer diameter in the cross-section perpendicular to the longitudinal direction of the reflection vibrator is Dr, the outer diameter ratio Dr / Ds is 0.2 to 6.0, the specific acoustic impedance Zr of the reflection vibrator is 1×10 ７ to 2×10 ８ kg·m －２ ·sec －１ and the hollow portion of the reflection vibrator is filled with a liquid or gas having a specific acoustic impedance Zi different from the specific acoustic impedance Zr.

2. The hollow portion of the reflection vibrator is filled with a gas having a ratio of the specific acoustic impedance Zi / Zr of 1×10 －３ or less. The ultrasonic processing method according to claim 1.

3. The ultrasonic treatment method according to claim 2, wherein the thickness tr of the reflection vibrator is 0.2 to 3.0 mm.

4. The ultrasonic treatment method according to claim 1, wherein the treatment liquid has a dissolved gas amount of 80% or more of the saturated dissolved gas amount, and the hollow portion of the reflection vibrator is filled with a liquid having a dissolved gas amount of less than 50% of the saturated dissolved gas amount.

5. The ultrasonic treatment method according to claim 1, wherein the hollow portion of the reflection vibrator is filled with the treatment liquid.

6. The ultrasonic treatment method according to claim 4 or 5, wherein the thickness tr of the reflection vibrator is 3.0 to 20.0 mm.

7. The ultrasonic treatment method according to any one of claims 1 to 6, wherein, when the length of the object to be treated in the longitudinal direction is Ls and the length of the reflection vibrator in the longitudinal direction is Lr, the ratio of lengths Lr / Ls satisfies the relationship 0.7 ≦ Lr / Ls ≦ 3.

0.

8. The ultrasonic treatment method according to any one of claims 1 to 7, wherein a flange portion is provided on the outer surface of the reflection vibrator.

9. The ultrasonic treatment method according to claim 8, wherein when the cross-sectional size of the reflection vibrator at the portion where the flange portion is provided is Df, the ratio of cross-sectional sizes Df / Dr satisfies the relationship 1.1 ≦ Df / Dr ≦ 3.

0.

10. The ultrasonic treatment method according to claim 8 or 9, wherein the flange portion has a transverse elastic modulus G of 15 to 250 GPa.

11. The ultrasonic treatment method according to any one of claims 8 to 10, wherein the thickness tf of the flange portion is 2.0 to 10.0 times the thickness tr of the reflection vibrator.

12. The ultrasonic treatment method according to any one of claims 8 to 11, wherein the flange portion is provided so as to be in contact with the object to be treated at least at one location within a range of 5 m of the length of the object to be treated along the longitudinal direction of the object to be treated.

13. An ultrasonic treatment apparatus comprising: a treatment tank having a long axis with a substantially identical cross-sectional shape and containing a plurality of objects to be treated extending in the longitudinal direction and a treatment liquid for immersing the objects to be treated; and an ultrasonic application mechanism for applying ultrasonic waves to the treatment liquid, wherein each of the objects to be treated is arranged so as to be in contact with one or more other objects to be treated at at least two locations, one or more hollow reflection vibration bodies extending in the longitudinal direction are arranged in the treatment tank in a state of being immersed in the treatment liquid, each of the reflection vibration bodies is arranged so as to be in contact with the other objects to be treated at at least two locations, when the maximum value of the outer diameter in the cross-section perpendicular to the longitudinal direction of the object to be treated is Ds and the maximum value of the outer diameter in the cross-section perpendicular to the longitudinal direction of the reflection vibration body is Dr, the outer diameter ratio Dr / Ds is 0.2 to 6.0, the specific acoustic impedance Zi of the reflection vibration body is 1×10 ７ to 2×10 ８ kg·m －２ ·sec －１ , and the hollow portion of the reflection vibration body is filled with a liquid or gas having a specific acoustic impedance Zr different from the specific acoustic impedance Zi.