Inner wall peening system for hollow spiral extension member, and method for peening a hollow spiral extension member using the same.

Abstract

The present invention discloses an inner wall peening system for a hollow helical extension member, which includes a configuration for supplying an ultrasonic transmission medium for ultrasonic cavitation to the peening target area of ​​the target object. [Solution] The inner wall peening system includes a medium tank 110 for containing an ultrasonic transmission medium, a connecting pipe 120 connected to the hollow spiral extension member E and the medium tank respectively, forming a flow path for the ultrasonic transmission medium M from the medium tank to the inside of the hollow spiral extension member, a pressure regulator 130 connected to the medium tank and configured to adjust the pressure inside the medium tank to control the flow of the ultrasonic transmission medium, and an ultrasonic generator 140 provided in the connecting pipe and configured to generate ultrasonic waves from inside the connecting pipe toward the inside of the hollow spiral extension member so that ultrasonic cavitation peening is performed on the inner wall of the hollow spiral extension member when the inside of the hollow spiral extension member is filled with an ultrasonic transmission medium.

Description

Technical Field

[0001] The present invention relates to an inner wall peening system for a hollow spiral extension member configured to perform peening on the inner wall of an object by ultrasonic cavitation, and a peening method for a hollow spiral extension member using the same. More specifically, the present invention relates to an inner wall peening system for a hollow spiral extension member, including a configuration for supplying an ultrasonic transmission medium for ultrasonic cavitation to a peening target region of an object, and a peening method for a hollow spiral extension member using the same.

Background Art

[0002] In a hollow spiral pipe, the cross-sectional area decreases by the amount of the hollow region, so weight reduction is possible. On the other hand, in the case of a hollow spiral extension member that receives a repeated load, it is necessary to achieve a fatigue strength of a certain standard or more on both the wall (outer surface) and the inner wall (inner surface). Here, in order to achieve a fatigue strength of a hollow spiral pipe at a certain level or more, a peening operation can be performed.

[0003] The peening operation is required, for example, for the outer wall and inner wall of a pipe in order to achieve fatigue strength because a heat exchanger in the form of a spiral pipe provided in a power generation facility receives repeated thermal stress, and is also required to reduce the tensile residual stress generated on the inner wall of various nozzles connected to a reactor pressure vessel in some cases.

[0004] Peening is a surface treatment method that improves residual stress and fatigue strength by applying plastic deformation to the surface layer of a material through impact. Shot peening, which is commonly used, is a method that improves the fatigue strength of a pipe by projecting small-diameter steel balls called shot balls onto the outer and inner surfaces of a pipe and hammering them, thereby applying compressive residual stress to the outer and inner surfaces of the shot-peened pipe. Compressive residual stress refers to the stress that remains in a material even after all external forces have been removed following plastic deformation. The compressive residual stress applied to the surface of the workpiece through the peening process can extend the fatigue life of the workpiece.

[0005] However, when the hollow cross-section formed in the pipe is extremely small, or when the pipe has a complex shape including curved sections, it is not easy to insert equipment for shot peening. In addition to shot peening, water jet peening and laser peening are also difficult to perform on the inner walls of pipes where access is restricted.

[0006] Ultrasonic cavitation peening can be applied to the inner wall of such hollow spiral pipes. Ultrasonic cavitation peening is a method in which an ultrasonic sound field is created inside the hollow spiral pipe by an ultrasonic probe inserted into the pipe, and peening is performed on the inner wall of the hollow spiral pipe through the process of ultrasonic cavity generation and explosion caused by this sound field.

[0007] On the other hand, in ultrasonic cavitation peening, it is conceivable to develop a method for more efficiently supplying the ultrasonic transmission medium, which generates the aforementioned cavities in the object to be peened using ultrasound, to the object to be peened. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] One object of the present invention is to provide an inner wall peening system for a hollow helical extension member that can more efficiently supply an ultrasonic transmission medium for ultrasonic cavitation to the inside of an object to be peened, and a method for peening a hollow helical extension member using the same.

[0009] Another object of the present invention is to provide an inner wall peening system for a hollow spiral extension member, and a peening method for a hollow spiral extension member using the same, which minimizes unwanted cavitation phenomena (i.e., weakens the generated ultrasonic intensity) that occur around the excitation probe by superimposing ultrasonic waves generated by multiple ultrasonic probes in phase synchronization inside the waveguide without excessively increasing the excitation displacement of the ultrasonic probe in ultrasonic cavitation peening, thereby minimizing the phenomenon of ultrasonic intensity reduction due to cavitation interference when the ultrasonic waves pass through the cavitation region, and thereby enabling ultrasonic waves with a constant intensity to reach the part of the object to be peened.

[0010] Another object of the present invention is to provide an inner wall peening system for a hollow spiral extension member, and a method for peening a hollow spiral extension member using the same, which can prevent the phenomenon in which the propagation of ultrasonic waves is restricted or blocked and the peening efficiency is reduced, by smoothly discharging macrobubbles generated in the process of peening the inner wall of a vertical tube using ultrasonic cavitation to the outside. [Means for solving the problem]

[0011] To achieve the object of the present invention, an inner wall peening system for a hollow helical extension member according to one embodiment of the present invention includes: a medium tank for containing an ultrasonic transmission medium; a connecting pipe having one end connected to a hollow helical extension member and the other end connected to the medium tank, forming a flow path for the ultrasonic transmission medium from the medium tank to the interior of the hollow helical extension member; a pressure regulator connected to the medium tank and configured to control the flow of the ultrasonic transmission medium by adjusting the pressure inside the medium tank; and an ultrasonic generator provided in the connecting pipe and configured to generate ultrasonic waves from inside the connecting pipe toward the interior of the hollow helical extension member so that ultrasonic cavitation peening is performed on the inner wall of the hollow helical extension member when the interior of the hollow helical extension member is filled with the ultrasonic transmission medium.

[0012] According to one example of the present invention, one end of the connecting pipe may be provided with a connecting tube that is detachably connected to the lower end of the hollow spiral extension member.

[0013] According to one example of the present invention, the ultrasonic probe that generates ultrasonic waves in the ultrasonic generator may be positioned toward the opening of the connecting tube.

[0014] According to one example of the present invention, when the pressure is released while the ultrasonic transmission medium is filled inside the hollow spiral extension member by the pressurization of the pressure regulator, the upper end of the medium tank may be positioned lower than the connecting tube, and the other end of the connecting pipe may be connected to the bottom of the medium tank, so that when the pressurization is released, the ultrasonic transmission medium is completely discharged from the hollow spiral extension member by gravity.

[0015] According to one example of the present invention, the invention may further include an extension tube that is detachably coupled to the upper end of the hollow spiral extension member and extends upward, such that the ultrasonic transmission medium is completely filled inside the hollow spiral extension member and stable position control of the pressure antinode is possible throughout the entire interior of the hollow spiral extension member.

[0016] According to one example of the present invention, the pressure regulator may be configured to adjust the water level of the ultrasonic transmission medium in the extension tube by adjusting the pressure.

[0017] According to one example of the present invention, the pressure regulator may be configured to adjust the filling water level of the ultrasonic transmission medium so that ultrasonic cavitation peening is performed on the inner wall of the hollow spiral extension member when the water level of the ultrasonic transmission medium in the extension tube exceeds the end surface of the extension tube and the ultrasonic transmission medium leaks out to the outside.

[0018] According to one example of the present invention, the ultrasonic probe that generates ultrasonic waves in the ultrasonic generator is configured to penetrate the connecting tube and at least a portion of it is located inside the connecting tube, and the portion of the connecting tube through which the ultrasonic probe penetrates is provided with a sealing member for sealing and a coating member made of a metal or non-metallic material to protect the surface of one end of the ultrasonic probe and to be coated on the surface of one end of the ultrasonic probe, and the sealing member may be positioned at the pressure anti-node of the ultrasonic probe where the vibration displacement is zero when ultrasonic waves are generated.

[0019] According to one example of the present invention, the hollow spiral extension member is a hollow coil spring, and the inner wall peening system of the hollow spiral extension member may further include a pressurizing jig configured to support the lower side of the hollow coil spring and pressurize the upper side downward so as to maintain the hollow coil spring in a compressed state during the ultrasonic cavitation peening process.

[0020] According to one example of the present invention, the present invention further includes an extension tube connected between one end and the other end, having a plurality of openings, to which an ultrasonic probe may be attached.

[0021] According to one example of the present invention, the extension pipe includes a branching section that branches a communication section, which has a single opening communicating with the connecting pipe, into a plurality of openings, and the branching section may be located at an equidistant distance from each of the plurality of openings such that ultrasonic waves incident on each of the plurality of openings overlap at the branching section.

[0022] According to one example of the present invention, the present invention further includes an extension pipe connected between one end and the other end, the extension pipe may include a communication portion communicating with the connecting pipe, an ultrasonic probe mounting portion forming a space for mounting an ultrasonic probe configured to generate ultrasonic waves toward the communication portion, and a bubble discharge portion extending in a branching manner from between the communication portion and the ultrasonic probe mounting portion so that bubbles generated during peening by the ultrasonic probe rise and are discharged by buoyancy.

[0023] A peening method for a hollow spiral extension member using the inner wall peening system according to another embodiment of the present invention includes the steps of: connecting the lower end of the hollow spiral extension member to the connecting pipe; controlling the pressure regulator to fill the inside of the hollow spiral extension member with the ultrasonic transmission medium; operating the ultrasonic generator to perform ultrasonic cavitation peening on the inner wall of the hollow spiral extension member; controlling the pressure regulator to change the position of the pressure antinode, which is the ultrasonic cavitation peening point; controlling the pressure regulator to recover the ultrasonic transmission medium filled inside the hollow spiral extension member into the medium tank; and separating the hollow spiral extension member from the connecting pipe.

[0024] The inner wall peening system of the hollow spiral extension member according to another embodiment of the present invention includes a medium supply unit configured to supply and recover an ultrasonic transmission medium, a hollow spiral extension member and a connection pipe respectively connected to the medium supply unit, the connection pipe forming a flow path for the ultrasonic transmission medium to move from the medium supply unit into the hollow spiral extension member, an ultrasonic probe for generating ultrasonic waves provided to penetrate the connection pipe, and an ultrasonic generator configured to generate ultrasonic waves from the inside of the connection pipe toward the inside of the hollow spiral extension member so that ultrasonic cavitation peening is performed on the inner wall of the hollow spiral extension member in a state where the hollow spiral extension member is filled with the ultrasonic transmission medium, and a seal member provided at a portion of the connection pipe through which the ultrasonic probe penetrates, wherein the seal member is disposed at the position of the pressure anti-node of the ultrasonic probe where the vibration displacement becomes zero during ultrasonic wave generation.

[0025] According to an example of the present invention, the connection pipe is connected to the lower end of the hollow spiral extension member, and the inner wall peening system of the hollow spiral extension member may further include an extension tube detachably coupled to the upper end of the hollow spiral extension member and extending upward so that the ultrasonic transmission medium completely fills the inside of the hollow spiral extension member and stable position control of the pressure anti-node is possible throughout the inside of the hollow spiral extension member.

Effects of the Invention

[0026] The effects of the present invention obtained by the above-described solution are as follows.

[0027] First, the inner wall peening system of the hollow spiral extension member includes a media tank for accommodating an ultrasonic transmission medium, a connecting pipe connected to the hollow spiral extension member and the media tank respectively to form a moving flow path of the ultrasonic transmission medium, a pressure regulator for adjusting the pressure inside the media tank to control the flow rate of the ultrasonic transmission medium, and an ultrasonic generator for generating ultrasonic waves in a state where the inside of the hollow spiral extension member is filled with the media and generating ultrasonic cavitation peening on the inner wall of the hollow spiral extension member by generating ultrasonic waves from the inside of the connecting pipe toward the inside of the hollow spiral extension member.

[0028] According to the configuration of such an inner wall peening system of the hollow spiral extension member, the filling level of the ultrasonic transmission medium supplied to the inside of the hollow spiral extension member can be easily controlled using the pressure regulator, and the supply and recovery of the ultrasonic transmission medium are performed more stably, so that an inner wall peening system of the hollow spiral extension member capable of improving the efficiency of the peening operation can be provided.

[0029] Second, the inner wall peening system of the hollow spiral extension member includes a connecting pipe having a first side portion having a single opening communicating with the hollow spiral extension member and the media tank, a second side portion, and a third side portion branched between the first side portion and the second side portion and having a plurality of openings. By controlling a plurality of ultrasonic probes in the same phase without excessively increasing the vibration displacement of the ultrasonic probes, after propagating the same distance without ultrasonic intensity loss inside the connecting pipe, they overlap with each other in the same phase at the branch portion, and can reach the hollow spiral extension member in a state where the vibration displacement increases at the branch portion. Thereby, while suppressing unnecessary cavitation formed around the probe, the intensity of the sound field in the target region can be increased and the cavitation efficiency can be improved.

[0030] Thirdly, the inner wall peening system of the hollow spiral extension member is provided with a bubble discharge section branched between the first and second sides of the connecting pipe and the third side extending from it, allowing bubbles generated during the ultrasonic peening process to rise naturally due to buoyancy and be discharged to the outside. This effectively prevents the scattering and blocking of ultrasonic waves by macrobubbles accumulated in the object being peened and the waveguide, maintaining a constant effective acoustic intensity inside the object being peened and ensuring stable peening efficiency. [Brief explanation of the drawing]

[0031] [Figure 1] This is a conceptual diagram showing the configuration of an inner wall peening system for a hollow spiral extension member according to one embodiment of the present invention. [Figure 2] Figure 1 is a conceptual diagram showing the hollow spiral extension member connected to the connecting pipe. [Figure 3] Figure 1 is a conceptual diagram showing the state in which the ultrasonic transmission medium is filled inside the hollow spiral extension member by controlling the pressure regulator shown in Figure 1. [Figure 4] Figure 1 is a conceptual diagram showing how ultrasonic cavitation peening is performed by operating the ultrasonic generator shown in Figure 1. [Figure 5] This is a conceptual diagram showing how the pressure regulator shown in Figure 1 controls the process of recovering the ultrasonic transmission medium filled inside the hollow spiral extension member into the medium tank. [Figure 6] Figure 1 is a conceptual diagram showing how the hollow spiral extension member is separated from the connecting pipe. [Figure 7] Figure 1 is a conceptual diagram showing another example of the interior wall peening system. [Figure 8] This is a conceptual diagram of an inner wall peening system having multiple ultrasonic probes according to another embodiment of the present invention. [Figure 9] Figure 8 is a conceptual diagram showing another example of an internal wall peening system having multiple ultrasonic probes. [Figure 10]This is a conceptual diagram of an inner wall peening system for a hollow spiral extension member having a bubble discharge section according to one embodiment of the present invention. [Figure 11] Figure 10 is a conceptual diagram showing another example of an inner wall peening system having a bubble discharge section. [Figure 12] Figure 10 is a conceptual diagram of an inner wall peening system equipped with multiple bubble discharge sections. [Figure 13] This flowchart shows a method for peening a hollow spiral extension member using an inner wall peening system according to another embodiment of the present invention. [Modes for carrying out the invention]

[0032] The inner wall peening system 100 for a hollow spiral extension member according to the present invention, and the peening method for a hollow spiral extension member E using the same, will be described in more detail below with reference to the drawings.

[0033] In this specification, even if the embodiments are different, identical and similar configurations will be given the same and similar reference numerals, and redundant descriptions thereof will be omitted.

[0034] Unless otherwise clearly indicated by the context, singular expressions include plural expressions.

[0035] Figure 1 is a conceptual diagram showing the configuration of an inner wall peening system 100 for a hollow spiral extension member according to one embodiment of the present invention. Figure 2 is a conceptual diagram showing the state in which the hollow spiral extension member E shown in Figure 1 is connected to the connecting pipe 120. Figure 3 is a conceptual diagram showing the state in which the ultrasonic transmission medium M is filled inside the hollow spiral extension member E by controlling the pressure regulator 130 shown in Figure 1. Figure 4 is a conceptual diagram showing the process of performing ultrasonic cavitation peening by operating the ultrasonic generator 140 shown in Figure 1. Figure 5 is a conceptual diagram showing the process of recovering the ultrasonic transmission medium M filled inside the hollow spiral extension member E into the medium tank 110 by controlling the pressure regulator 130 shown in Figure 1. Figure 6 is a conceptual diagram showing the process of separating the hollow spiral extension member E shown in Figure 1 from the connecting pipe 120.

[0036] Referring to Figures 1 to 6, the inner wall peening system 100 for the hollow helical extension member may be configured to perform peening work on the inner wall of the hollow helical extension member E. Peening is a surface treatment method that improves residual stress and fatigue strength by applying plastic deformation to the surface layer of a material by impact. The inner wall peening system 100 for the hollow helical extension member is configured to include a peening method using ultrasonic cavitation. Ultrasonic cavitation peening is a peening method in which an ultrasonic sound field is formed inside the hollow helical extension member E by an ultrasonic generator 140 that is arranged to communicate with the inside of the hollow helical extension member E, and peening is performed on the inner wall of the hollow helical extension member E through the process of ultrasonic cavity, i.e., pore, being generated and exploding by this sound field.

[0037] The cavity formed within the ultrasonic transmission medium M by ultrasonic waves comes into contact with the inner wall of the hollow helical extension member E, instantaneously generating pressure of several hundred atmospheres or more and high heat in a short time of several tens of milliseconds, thereby applying compressive residual stress to the inner wall surface of the hollow helical extension member E, which is the object to be treated, and enabling the inner wall of the hollow helical extension member E to be peened.

[0038] On the other hand, the hollow spiral extension member E may be formed to have a spiral exterior and a hollow interior. At least one end of the ends of the hollow spiral extension member E may be formed to be open.

[0039] The inner wall peening system 100 of the hollow spiral extension member includes a medium tank 110, a connecting pipe 120, a pressure regulator 130, and an ultrasonic generator 140.

[0040] The medium tank 110 is formed to accommodate the ultrasonic transmission medium M. The ultrasonic transmission medium M is a substance used to transmit ultrasonic waves generated by the ultrasonic generator 140 (described later) into the hollow spiral extension member E. The ultrasonic transmission medium M may be composed of, for example, water, gel, or various oils. Furthermore, since dissolved gases in the solution may reduce the intensity of cavitation, the ultrasonic transmission medium M may be configured in a degassed state in which dissolved gases are completely removed.

[0041] The connecting pipe 120 is connected to the hollow spiral extension member E and the medium tank 110, respectively, and forms a flow path for the ultrasonic transmission medium M from the medium tank 110 into the interior of the hollow spiral extension member E.

[0042] The pressure regulator 130 is connected to the medium tank 110 and is configured to regulate the pressure inside the medium tank 110 to control the filling level of the ultrasonic transmission medium M. The pressure regulator 130 may be configured to adjust the pressure inside the medium tank 110 to positive or negative pressure. For example, when the pressure inside the medium tank 110 becomes positive, the ultrasonic transmission medium M may move from the medium tank 110 to the hollow spiral extension member E, and conversely, when the pressure inside the medium tank 110 becomes negative, the ultrasonic transmission medium M may move from the hollow spiral extension member E to the medium tank 110.

[0043] Furthermore, although Figures 1 to 7 show the pressure regulator 130 connected to the upper side of the medium tank 110, the pressure regulator 130 may be connected to other parts of the medium tank 110. For example, the pressure regulator 130 may be connected to the lower side of the medium tank 110. In this case, unlike when the pressure regulator 130 is located on the upper side of the medium tank 110, at least a portion of the pressure regulator 130 may be immersed in the ultrasonic transmission medium M contained in the medium tank 110.

[0044] The ultrasonic generator 140 may be provided in the connecting pipe 120. The ultrasonic generator 140 may have an ultrasonic probe 141 that generates ultrasonic waves. The ultrasonic probe 141 may be made of titanium or aluminum. The ultrasonic probe 141 may have a probe tip 141a at one end. The ultrasonic probe tip 141a may be formed by being coupled to one end of the ultrasonic probe 141. On the other hand, the ultrasonic probe tip 141a may be manufactured integrally with the ultrasonic probe 141 and point to one end of the ultrasonic probe 141. The ultrasonic probe 141 of the ultrasonic generator 140 may be arranged to penetrate from the outside to the inside of the connecting pipe 120. The connecting pipe 120 may be provided with an ultrasonic probe mounting portion 124 for attaching the ultrasonic probe 141. The ultrasonic generator 140 may be configured to generate ultrasonic waves from inside the connecting tube toward the inside of the hollow spiral extension member E, as shown in Figure 4, so that ultrasonic cavitation peening is performed against the inner wall of the hollow spiral extension member E, with the inside of the hollow spiral extension member E filled with an ultrasonic transmission medium M. At this time, the probe tip 141a may be immersed in the medium.

[0045] Furthermore, the inner wall peening system 100 of the hollow spiral extension member may further include a coating member (not shown). The coating member may be made of a metallic or non-metallic material to protect the surface of one end of the ultrasonic probe 141, which is subjected to ultrasonic cavitation by ultrasonic waves generated by the ultrasonic generator 140, from ultrasonic cavitation, and may be formed to coat one end of the ultrasonic probe 141. For example, the coating member may be made of a metallic material such as tungsten, or a non-metallic material such as diamond. This improves the durability of the ultrasonic probe 141, allows for more stable ultrasonic wave generation, and extends the service life of the ultrasonic probe 141.

[0046] In the peening step in which a cavity is generated in the ultrasonic transmission medium M by ultrasound, the ultrasonic probe 141 of the ultrasonic generator 140 may be positioned so that at least a portion of it is immersed in the ultrasonic transmission medium M and is configured to transmit ultrasound through the ultrasonic transmission medium M.

[0047] The ultrasonic probe 141 of the ultrasonic generator 140 may be configured to generate ultrasonic waves in the ultrasonic transmission medium M by vibrating the ultrasonic transmission medium M, which is in contact with the probe tip 141a of the ultrasonic probe 141, while resonating in the axial direction of the ultrasonic probe 141. However, the ultrasonic probe 141 may be configured to generate ultrasonic waves in the ultrasonic transmission medium M by vibrating the ultrasonic transmission medium M in a non-resonant state, in addition to the vibration method by resonance.

[0048] On the other hand, if the ultrasonic probe 141 resonates in the axial direction, a standing wave may be formed in the axial direction. Furthermore, the ultrasonic probe 141 may have pressure nodes where the axial pressure is zero, and pressure anti-nodes P1, P2, and P3 where the vibrational displacement is zero. More specifically, the ultrasonic waves generated by the ultrasonic probe 141 may be totally reflected at the interface between the ultrasonic transmission medium M filled in the hollow spiral extension member E and the air in contact with it, forming a standing wave. When a standing wave is formed, high pressure is generated at the pressure anti-nodes P1, P2, and P3, causing concentrated cavitation. To prevent peening from occurring only at specific locations where the pressure anti-nodes P1, P2, and P3 are formed, it is necessary to adjust the interface with the air where total reflection occurs. This allows for adjusting the water level of the ultrasonic transmission medium M to shift the peening region where the pressure anti-nodes P1, P2, and P3 are formed, enabling uniform peening across the entire inner wall.

[0049] According to another example of the present invention, when the ultrasonic probe 141 resonates in the axial direction, traveling waves may be formed along with standing waves. If traveling waves are more dominant, pressure antinodes P1, P2, and P3 are not formed, and thus uniform inner wall peening can be achieved over the entire area without adjusting the filling water level of the ultrasonic transmission medium.

[0050] The following explanation details the case in which pressure antinodes P1, P2, and P3 are formed by standing waves.

[0051] When the ultrasonic probe 141 is vibrated at the axial resonance frequency of the ultrasonic probe 141, vibrational displacement will not occur near the point where it is (2n-1)(λ / 4) from one end of the probe tip 141a of the ultrasonic probe 141, with reference to the probe tip 141a. That is, the pressure antinodes P1, P2, and P3 can be formed near the point where it is (2n-1)(λ / 4) from the probe tip 141a. Here, n is a natural number, and λ may be the axial wavelength of the ultrasound within the ultrasonic probe 141 generated by the resonance frequency that causes the ultrasonic probe 141 to resonate in the axial direction. According to this, the first point P1 may be n=1, which is λ / 4 from the probe tip 141a; the second point P2 may be n=2, which is 3λ / 4 from the probe tip 141a; and the third point P3 may be n=3, which is 5λ / 4 from the probe tip 141a.

[0052] Theoretically, the pressure antinodes P1, P2, and P3 of the ultrasonic probe 141 are formed at a point (2n-1)(λ / 4) from the probe tip 141a. However, when the ultrasonic probe 141 is implemented as a device, various factors such as changes in vibration caused by other components coupled to the ultrasonic probe 141 may prevent the pressure antinodes P1, P2, and P3 from being formed precisely at a point (2n-1)(λ / 4) from the probe tip 141a, and instead cause them to be formed near the point where (2n-1)(λ / 4) is the correct position.

[0053] For the sake of explanation, in the following description, it will be assumed that the pressure antinodes P1, P2, and P3 of the ultrasonic probe 141 are formed at a point (2n-1)(λ / 4) from the probe tip 141a.

[0054] The pressure antinodes P1, P2, and P3 may be formed on the ultrasonic probe 141 at a first point P1, a second point P2, and a third point P3, etc. In other words, vibrational displacement, i.e., shape deformation, of the ultrasonic probe 141 does not occur at the first point P1, the second point P2, the third point P3, etc.

[0055] As a result, as shown in Figure 1, when the ultrasonic probe 141 vibrates, the pressure node where the maximum amplitude occurs is formed at the probe tip 141a. Furthermore, the first point P1, the second point P2, and the third point P3 can become pressure antinodes P1, P2, and P3, respectively, where the amplitude is 0, i.e., the vibration displacement is minimum and the pressure is maximum.

[0056] In order for the ultrasonic probe 141 to effectively generate ultrasound in the ultrasonic transmission medium M, in other words, in order to resonate the ultrasonic probe 141 during excitation, it is preferable that the probe tip 141a be the pressure node. That is, it is preferable that the length of the ultrasonic probe 141 be set so that resonance occurs depending on the excitation frequency. When the resonating ultrasonic probe 141 comes into contact with the ultrasonic transmission medium M and the ultrasonic transmission medium M is excited, ultrasound is propagated within the ultrasonic transmission medium M. Here, when the pressure node of the ultrasonic probe 141 having the maximum displacement becomes the excitation surface of the ultrasonic transmission medium M, the ultrasonic transmission medium M is excited to the maximum extent, and the propagated energy is also maximized.

[0057] Furthermore, the pressure antinodes formed in the ultrasonic transmission medium M filled inside the hollow spiral extension member E occur weekly rather than over the entire length of the hollow spiral extension member E, and peening is not performed at points that do not correspond to the pressure antinodes P1, P2, and P3. The hollow spiral extension member inner wall peening system 100 of the present invention can move the positions of the pressure antinodes P1, P2, and P3 by controlling the pressure regulator 130 to move the filling water level, which is the interface between the ultrasonic transmission medium M and air. The hollow spiral extension member inner wall peening system 100 can perform peening work on the entire inner wall of the hollow spiral extension member E by moving the positions of the pressure antinodes P1, P2, and P3 through a method of controlling the pressure regulator 130.

[0058] On the other hand, one end 121 of the connecting pipe 120 may be provided with a connecting tube 180 that is detachably connected to the lower end of the hollow spiral extension member E. The connecting tube 180 may have an opening 120a that connects to the inside of the hollow spiral extension member E. This allows the ultrasonic transmission medium M to be filled from the bottom to the top of the hollow spiral extension member E. The opening 120a may be positioned at a height H1 corresponding to the lower end of the hollow spiral extension member E.

[0059] Furthermore, the connecting tube 180 may be formed to surround one end of the hollow spiral extension member E. The connecting tube 180 can seal the portion where the connecting pipe 120 connects to the hollow spiral extension member E, thereby preventing leakage of the ultrasonic transmission medium M.

[0060] With this configuration of the hollow spiral extension member inner wall peening system 100, the ultrasonic transmission medium M can be stably supplied to the inside of the hollow spiral extension member E by filling it from the bottom to the top. When the inside of the hollow spiral extension member E is filled with the ultrasonic transmission medium M, the peening area can be controlled by adjusting the filling water level of the ultrasonic transmission medium M using the pressure regulator 130. Furthermore, after ultrasonic cavitation peening of the inner wall of the hollow spiral extension member E is completed, the ultrasonic transmission medium M can be stably recovered into the medium tank 110 via the connecting pipe 120.

[0061] On the other hand, the height H2 of the upper end of the media tank 110 may be lower than the height H1 where the connecting tube 180 is formed. This allows the ultrasonic transmission medium M to be completely discharged from the hollow spiral extension member E by gravity when the pressure is released while the inside of the hollow spiral extension member E is filled with ultrasonic transmission medium M by the pressurization of the pressure regulator 130.

[0062] With this structure, when the media tank 110 and connecting pipe 120 are under atmospheric pressure, the ultrasonic transmission medium M filled inside the hollow spiral extension member E can be recovered into the media tank 110 by gravity. At this time, the height H1 of the opening 120a formed in the connecting tube 180 may be higher than the height H2 of the upper end of the media tank 110, and the ultrasonic transmission medium M may form a water level lower than the opening 120a. This prevents the ultrasonic transmission medium M from overflowing to the outside through the connecting tube 180.

[0063] On the other hand, when recovering the ultrasonic transmission medium M filled inside the hollow spiral extension member E, a method may be used in which the operation of the pressure regulator 130 is stopped and atmospheric pressure is formed inside the medium tank 110 and connecting pipe 120. However, during the process of recovering the ultrasonic transmission medium M, the system may be configured not to maintain atmospheric pressure inside the medium tank 110 and connecting pipe 120 through the operation of the pressure regulator 130. That is, the system may be configured to recover the ultrasonic transmission medium M inside the medium tank 110 by forming negative pressure inside the medium tank 110. However, the method of recovering the ultrasonic transmission medium M by forming atmospheric pressure inside the medium tank 110 and connecting pipe 120 has the advantage of reducing energy consumption due to the operation of the pressure regulator 130 and simplifying the peening operation, as it does not require the operation of the pressure regulator 130.

[0064] On the other hand, the other end 122 of the connecting pipe 120 may be connected to the bottom of the medium tank 110. This allows the ultrasonic transmission medium M contained in the medium tank 110 to be smoothly discharged from the bottom of the medium tank 110 through the other end 122 of the connecting pipe 120 to the outside of the medium tank 110. In the drawings of the present invention, the other end 122 of the connecting pipe 120 is shown to extend vertically downward, but it may extend downward at a certain angle rather than vertically.

[0065] The connecting pipe 120 may have extensions 123 at both ends that connect to the other end 122 and one end 121 of the connecting pipe 120, respectively. As shown in the drawings of the present invention, the other end 122 and extension 123 of the connecting pipe 120 may be formed in a "U" shape. Although not shown in the drawings of the present invention, the other end 122 and extension 123 of the connecting pipe 120 may also be formed in a "U" shape instead of a "U" shape.

[0066] Furthermore, the ultrasonic probe 141 of the ultrasonic generator 140 may be positioned to face the opening 120a of the connecting tube 180. With such a structure for the ultrasonic probe 141, there is no structure that interferes with the propagation of ultrasonic waves within the connecting tube 120 until the generated ultrasonic waves pass through the connecting tube 180 and move into the hollow spiral extension member E. This reduces interference in the ultrasonic transmission section and minimizes energy loss. As a result, the quality of ultrasonic cavitation peening can be further improved.

[0067] Furthermore, the ultrasonic probe 141 may be configured to penetrate the connecting pipe 120 and be positioned at least partially within the connecting pipe 120. Here, the inner wall peening system 100 of the hollow spiral extension member may further include a sealing member 150.

[0068] The sealing member 150 may be positioned on the length portion of the ultrasonic probe 141 at locations corresponding to pressure antinodes P1, P2, and P3 where vibration displacement is zero during ultrasonic generation. For example, the sealing member 150 may be formed at the third point P3, which is one of the pressure antinodes P1, P2, and P3 shown in Figure 1. This prevents vibration from occurring in the sealing member 150 and the portion sealed by the sealing member 150, and allows for a more stable sealing effect between the tapered portion 125 and the outer surface of the ultrasonic probe 141.

[0069] Furthermore, the sealing member 150 may be provided at one end of the ultrasonic probe 141, i.e., at the pressure antinode near the bottom surface. This minimizes the contact area and thus minimizes energy loss due to contact friction.

[0070] In contrast, the sealing member 150 may be provided not on the ultrasonic probe 141 but on the portion through which the ultrasonic generator 140 penetrates the connecting pipe 120, provided that the ultrasonic generator 140 is installed so as to penetrate the connecting pipe 120. However, as shown in the drawings of the present invention, when the sealing member 150 is provided on the ultrasonic probe 141 instead of the ultrasonic generator 140, the contact area with the ultrasonic transmission medium M is reduced compared to when it is provided on the ultrasonic generator 140, thereby reducing energy loss due to friction with the ultrasonic transmission medium M. In other words, the structure in which the sealing member 150 is provided on the ultrasonic probe 141 minimizes energy loss compared to when the sealing member 150 is provided on the main body of the ultrasonic generator 140.

[0071] Furthermore, in the connecting pipe 120, a tapered portion 125 may be provided in the portion through which the ultrasonic probe 141 passes, formed to slope from the inside outwards. Here, the sealing member 150 may be placed in a recess 126 formed between the tapered portion 125 and the outer surface of the ultrasonic probe 141, and may be formed to seal the portion of the connecting pipe 120 through which the ultrasonic probe 141 passes. With such a structure for the sealing member 150, as the pressure inside the connecting pipe 120 increases due to the pressure regulator 130, it is pushed outwards, i.e., to the right with respect to Figure 1, and is configured to fit more tightly against the tapered portion 125. As a result, the sealing force of the portion of the connecting pipe 120 through which the ultrasonic probe 141 passes can be further improved. The sealing member 150 may be formed from an elastically deformable material.

[0072] On the other hand, the inner wall peening system 100 of the hollow spiral extension member may further include a cooler 160.

[0073] The cooler 160 may be provided in the medium tank 110 to suppress the inflow of vapor from the ultrasonic transmission medium M into the cavity, and may be configured to maintain the temperature of the ultrasonic transmission medium M contained in the medium tank 110 at or below a preset temperature.

[0074] The cavity generated by ultrasound bursts, generating a shock wave, which peens the surface. Therefore, a larger shock wave is advantageous for enhancing the peening effect. However, if the temperature of the ultrasonic transmission medium M is high, a large amount of water vapor will fill the cavity. In this state, when the cavity bursts, the water vapor present inside absorbs the shock, reducing the amount of shock. The inner wall peening system 100 of the present invention can provide a more stable peening effect by lowering the temperature of the ultrasonic transmission medium M with the cooler 160.

[0075] On the other hand, the inner wall peening system 100 of the hollow spiral extension member may further include an extension tube 170.

[0076] The extension tube 170 may be detachably coupled to the upper end of the hollow spiral extension member E and extend upward so that the ultrasonic transmission medium M can be completely filled inside the hollow spiral extension member E.

[0077] The structure of the extension tube 170 allows for more stable control of the water level of the ultrasonic transmission medium M formed horizontally. The water level of the ultrasonic transmission medium M may be measured by an electronic level sensor or visually. The extension tube 170 may be made of a light-transmitting material to observe the water level of the ultrasonic transmission medium M.

[0078] The extension tube 170 can serve two functions: measuring the water level of the ultrasonic transmission medium M, and closing the other end of the hollow spiral extension member E to guide the ultrasonic transmission medium M to be completely filled up to the other end of the hollow spiral extension member E.

[0079] Furthermore, the extension tube 170 may be formed perpendicular to the ground such that the angle between the inner wall of the extension tube 170 and the water surface of the ultrasonic transmission medium M is perpendicular. With such a structure for the extension tube 170, the water surface forming the interface with the outside air and the inner wall of the extension tube 170 form a right angle, standing waves are formed one-dimensionally inside the hollow spiral extension member E, and pressure antinodes can be formed at equal intervals throughout the entire area including the upper end of the hollow spiral extension member E. As a result, the peening position corresponding to the position of the pressure antinodes can be stably controlled. In contrast, if the extension tube 170 is not used, the inner wall of the upper end of the hollow spiral extension member E is not perpendicular to the water surface, or even if the extension tube 170 is used, if the extension tube 170 is not formed perpendicular to the ground, that is, if the water surface and the inner wall of the extension tube 170 do not form a right angle, some of the pressure antinodes formed at the end of the hollow spiral extension member E adjacent to the extension tube 170 may be formed irregularly and not at equal intervals.

[0080] Furthermore, the pressure regulator 130 may be configured to adjust the filling water level of the ultrasonic transmission medium M in the extension tube 170 by adjusting the pressure. The pressure regulator 130 can adjust the filling water level so that the water level of the ultrasonic transmission medium M in the extension tube 170 leaks to the outside above the end surface of the extension tube 170 by adjusting the pressure of the pressure regulator 130. By adjusting the leveling of the ultrasonic transmission medium M in the extension tube 170 by adjusting the pressure of the pressure regulator 130, the positions of the pressure antinodes P1, P2, and P3 can be adjusted to achieve uniform peening.

[0081] On the other hand, the inner wall peening system 100 of the hollow spiral extension member may include a medium supply unit, a connecting pipe 120, an ultrasonic generator 140, and a sealing member 150.

[0082] The media supply unit may be configured to supply and collect the ultrasonic transmission medium M.

[0083] The connecting pipe 120 is connected to the hollow spiral extension member E and the medium supply unit, respectively, and forms a flow path for the ultrasonic transmission medium M from the medium supply unit to the inside of the hollow spiral extension member E. The connecting pipe 120 may also be connected to the lower end of the hollow spiral extension member E.

[0084] The ultrasonic generator 140 may be provided such that an ultrasonic probe 141 for generating ultrasonic waves penetrates the connecting pipe 120. The ultrasonic generator 140 is configured to generate ultrasonic waves from inside the connecting pipe 120 toward the inside of the hollow spiral extension member E, so that ultrasonic cavitation peening is performed against the inner wall of the hollow spiral extension member E, with the inside of the hollow spiral extension member E filled with an ultrasonic transmission medium M.

[0085] The sealing member 150 may be provided in the connecting pipe 120 at the portion through which the ultrasonic probe 141 passes. Here, the sealing member 150 may be positioned at the pressure anti-node of the ultrasonic probe 141, where the vibration displacement is zero when ultrasonic waves are generated by the ultrasonic probe 141.

[0086] In contrast, although not shown in the drawings of the present invention, the sealing member 150 may be provided not on the ultrasonic probe 141 but on the portion through which the ultrasonic generator 140 penetrates the connecting pipe 120, provided that the ultrasonic generator 140 is installed so as to penetrate the connecting pipe 120. However, when the sealing member 150 is provided on the ultrasonic probe 141 instead of the ultrasonic generator 140, the contact area with the ultrasonic transmission medium M is reduced compared to when it is provided on the ultrasonic generator 140, thereby reducing energy loss due to friction with the ultrasonic transmission medium M. In other words, the structure in which the sealing member 150 is provided on the ultrasonic probe 141 minimizes energy loss compared to when the sealing member 150 is provided on the main body of the ultrasonic generator 140.

[0087] Furthermore, the inner wall peening system 100 of the hollow spiral extension member may further include an extension tube 170.

[0088] The extension tube 170 may be detachably coupled to the upper end of the hollow spiral extension member E so that the inside of the hollow spiral extension member E can be completely filled with an ultrasonic transmission medium.

[0089] Furthermore, the medium supply unit may be configured to adjust the filling water level of the ultrasonic transmission medium in the extension tube. For example, the medium supply unit may be configured to adjust the pressure formed in the movement path of the ultrasonic transmission medium M to positive or negative pressure in order to control the flow of the ultrasonic transmission medium.

[0090] According to the configuration of the hollow spiral extension member inner wall peening system 100 described above, the water level of the ultrasonic transmission medium M supplied to the inside of the hollow spiral extension member E can be easily controlled using the pressure regulator 130, and the supply and recovery of the ultrasonic transmission medium M can be performed more stably, thereby improving the efficiency of the peening work.

[0091] Hereinafter, an inner wall peening system 100 for a hollow spiral extension member according to another example of the present invention will be described with reference to Figure 7.

[0092] Figure 7 is a conceptual diagram showing another example of the interior wall peening system 100 shown in Figure 1.

[0093] Referring to Figure 7, the hollow spiral extension member E may be a hollow coil spring. The hollow coil spring is characterized by being compressed when a physical force greater than a predetermined magnitude is applied, and by elasticity when the applied force is removed.

[0094] The pressurizing jig 210 may be configured to support the lower side of the hollow coil spring and apply pressure to the upper side downwards in order to maintain the hollow coil spring in a compressed state during the ultrasonic cavitation peening process. For example, the pressurizing jig 210 may be configured to apply pressure to the hollow coil spring in the vertical direction up to the yield stress of the hollow coil spring in order to induce plastic deformation of the hollow coil spring.

[0095] With this configuration of the pressurizing jig 210, by applying stress to the hollow coil spring in advance and performing ultrasonic cavitation peening while the stress value is close to the yield stress, the peening effect on the inner wall of the hollow coil spring can be further enhanced.

[0096] For reference, if the yield stress of a material is high, the material will remain within the elastic region even if peening is performed, and the peening effect will not be fully realized. In the present invention, the hollow coil spring is compressed by the pressurizing jig 210, and the stress of the hollow coil spring is raised to the yield stress, thereby creating a stress level just before plastic deformation occurs in the hollow coil spring, and the peening effect can be greatly improved.

[0097] Figure 8 is a conceptual diagram of an inner wall peening system 100 having a plurality of ultrasonic probes 141 according to another embodiment of the present invention, and Figure 9 is a conceptual diagram showing another example of the inner wall peening system 100 having a plurality of ultrasonic probes 141 shown in Figure 8.

[0098] Referring to Figures 8 and 9, the inner wall peening system 100 of the hollow spiral extension member E may further include an extension tube 190 having multiple openings, connected between one end 121 and the other end 122.

[0099] The extension pipe 190 may be configured to branch off from the connecting pipe 120 in the side wall section via a connecting section 191. Here, the connecting section 191 refers to a connection area formed so that the internal flow path of the connecting pipe 120 and the internal flow path of the extension pipe 190 communicate with each other. The central axis of the extension pipe 190 may be perpendicular to the central axis of the connecting pipe 120, but is not limited to this, and may be acute, obtuse, or horizontal.

[0100] If the central axis of the extension tube 190 and the central axis of the connecting tube 120 are horizontal, the ultrasonic transmission medium M may easily flow out along the gap between the ultrasonic probe 141 and the multiple openings of the extension tube 190 in the direction of gravity. Therefore, each of the multiple openings may be provided with a sealing member 150 to prevent leakage of the ultrasonic transmission medium M.

[0101] An ultrasonic probe 141 may be attached to each of the multiple openings of the extension tube 190. Each of the multiple openings may be called an ultrasonic probe mounting section 124. Multiple ultrasonic probes 141 attached to each of the multiple ultrasonic probe mounting sections 124 can generate ultrasonic waves with the same phase.

[0102] Depending on the application and manufacturability, the extension tube 190 may be formed integrally with the connecting tube 120, or it may be connected to the connecting tube 120 as a separate tubular component at a connecting portion 191. When it is connected to the connecting tube 120, depending on the shape, seal, and reinforcing structure of the connecting portion 191, leakage prevention, reduction of flow loss, and improvement of structural durability can be achieved. The extension tube 190 may be formed from a material whose acoustic impedance difference with the ultrasonic transmission medium M is greater than or equal to a predetermined value in order to block the emission of ultrasonic waves to the outside of the extension tube 190. For example, the extension tube 190 may be formed from metal or glass material, but is not limited to these.

[0103] The extension pipe 190 may include a branching section 192 that branches a communication section 191, which has a single opening communicating with the connecting pipe 120, into a plurality of openings. The branching section 192 may be positioned equidistant from each of the plurality of openings such that the ultrasonic waves incident on each of the plurality of openings overlap at the branching section 192. The plurality of openings may be called ultrasonic probe mounting sections 124 to which the ultrasonic probe 141 is attached.

[0104] The ultrasonic probe mounting portion 124 of the extension tube 190 may be formed in two parts. In this case, each of the ultrasonic probe mounting portions 124 may be positioned to face each other with respect to the branching portion 192. More specifically, each of the multiple ultrasonic probe mounting portions 124 may be located at the same distance from the branching portion 192 such that the ultrasonic waves incident on each of them overlap at the branching portion 192 in the same phase. As described above, the extension tube 190 may be formed in a "Y" shape, a partially bent "Y" shape, or a curved shape.

[0105] The extension tube 190 may have three or more ultrasonic probe mounting portions 124. Each ultrasonic probe mounting portion 124 may be arranged at equal intervals so as to lie on the same radius with respect to the branching portion 192. The center of each ultrasonic probe mounting portion 124 may maintain the same radius from the center of the branching portion 192, and the same angle θ may be formed between the centerlines of adjacent ultrasonic probe mounting portions 124. As a result, the multiple ultrasonic probe mounting portions 124 have a shape arranged at equal intervals on the circumference, and the centers of each ultrasonic probe mounting portion 124 can be uniformly distributed along the circumference. For example, if there are three ultrasonic probe mounting portions 124, the angle θ is preferably formed at 120°, and if there are four ultrasonic probe mounting portions 124, the angle θ is preferably formed at 90°.

[0106] As the number of ultrasonic probe mounting sections 124 increases, the number of ultrasonic probes 141 attached to each ultrasonic probe mounting section 124 also increases, and the total energy of the overlapping ultrasonic waves inside the extension tube 190 can become even greater.

[0107] Figure 10 is a conceptual diagram of an inner wall peening system 100 of a hollow spiral extension member E having a bubble discharge section 193 according to one embodiment of the present invention, and Figure 11 is a conceptual diagram showing another example of the inner wall peening system 100 having the bubble discharge section 193 shown in Figure 10.

[0108] Referring to Figures 10 and 11, the inner wall peening system 100 of the hollow spiral extension member E may further include an extension tube 190 having multiple openings, connected between one end 121 and the other end 122.

[0109] The extension pipe 190 may include a communication section 191 that communicates with the connecting pipe, an ultrasonic probe mounting section 124 that forms a space for mounting an ultrasonic probe 141 configured to generate ultrasonic waves toward the communication section 191, and a bubble discharge section 193.

[0110] The extension pipe 190 may be configured to branch off from the connecting pipe 120 via a connecting section 191 in the side wall section. Here, the connecting section 191 refers to a connection area formed so that the internal flow path of the connecting pipe 120 and the internal flow path of the extension pipe 190 communicate with each other. The central axis of the extension pipe 190 may be perpendicular to the central axis of the connecting pipe 120, but is not limited to this, and may be acute or obtuse.

[0111] The bubble discharge section 193 may extend from a branching section 192 located between the communication section 191 and the ultrasonic probe mounting section 124. The bubble discharge section 193 may be formed to protrude integrally from the branching section 192, or it may be formed by connecting a separate tube. The bubble discharge section 193 may extend upward so that macrobubbles B generated during ultrasonic peening rise due to buoyancy and are discharged to the outside. The bubble discharge section 193 may be formed as a cylindrical tube, and may be formed with different diameters depending on the size of the macrobubbles B. In this invention, macrobubbles B refer to bubbles formed to occupy 5% or more of the cross-sectional area of ​​the bubble discharge section 193. The bubble discharge section 193 branching from the extension tube 190 may be formed so that the length from the branching section 192 to the outlet from which the bubbles are discharged is greater than the height of the hollow spiral extension member E. In this case, the entire interior of the bubble discharge section 193 is not filled with the ultrasonic transmission medium M, and a portion of the section near the outlet may be formed to be in contact with the atmosphere.

[0112] On the other hand, the length of the bubble discharge section 193 may be formed to be lower than the height of the hollow spiral extension member E. In this case, a separation membrane 194 may be provided inside the bubble discharge section 193, which is formed to allow gas to pass through but restrict the passage of the ultrasonic transmission medium M. The separation membrane 194 can smoothly discharge bubbles generated during the peening process to the outside, and also suppress the unnecessary outflow of the ultrasonic transmission medium M inside the bubble discharge section 193 to the outside.

[0113] During peening, the macrobubbles B generated move to the upper side of the extension tube 190 due to buoyancy. At the ultrasonic probe mounting section 124, the ultrasonic probe 141 irradiates ultrasonic waves toward the hollow spiral extension member E. Therefore, bubbles moving directly toward the ultrasonic probe mounting section 124 may have their progress suppressed or inhibited by the pressure gradient and flow caused by the acoustic radiation of the ultrasonic waves. As a result, the macrobubbles B cannot flow from the branching section 192 into the ultrasonic probe mounting section 124 and can be guided to the bubble discharge section 193, which has relatively less resistance, and discharged to the outside.

[0114] According to one embodiment of the present invention, the ultrasonic probe mounting portion 124 may be formed to be located above the communication portion 191 in a vertical direction. More specifically, the communication portion 191 and the ultrasonic probe mounting portion 124 may be arranged in a straight line with respect to each other, and a linear flow path may be formed between them. A bubble discharge portion 193 may be provided so as to branch off from the side wall of the flow path. The bubble discharge portion 193 may branch off from the branching portion 192 and be arranged at an upward inclination with respect to the vertical direction of the flow path. The closer the bubble discharge portion 193 is formed to the vertical direction, the greater the buoyancy that acts, and the efficiency of discharging the macrobubbles B can be improved.

[0115] According to yet another embodiment of the present invention, the bubble discharge section 193 may be formed to be positioned above the communication section 191 in a vertical direction. The ultrasonic probe mounting section 124 may be positioned above the communication section 191, offset laterally. In this case, the flow path connecting the ultrasonic probe mounting section 124 and the communication section 191 may be formed in a shape that bends at a certain angle. Even if the macrobubbles B generated during the ultrasonic peening process rise upward due to buoyancy, the refraction structure formed between the ultrasonic probe mounting section 124 and the communication section 191 makes it difficult for them to flow directly into the ultrasonic probe mounting section 124, and they can be guided to the bubble discharge section 193 branched from the branching section 192 and discharged to the outside.

[0116] Figure 12 is a conceptual diagram of an inner wall peening system 100, which is provided with multiple bubble discharge sections 193 as shown in Figure 10.

[0117] Referring to Figure 12, the bubble discharge section 193 in another embodiment of the present invention may be formed to branch out from multiple different positions on the extension pipe 190.

[0118] The bubble discharge section 193 may include a first discharge section 193a located at a specific position on the extension tube 190 for discharging microbubbles B', and a second discharge section 193b located at a different position on the extension tube 190 from the first discharge section 193a for discharging macrobubbles B. The second discharge section 193b may also be arranged in a different direction from the first discharge section 193a. For example, the first discharge section 193a and the second discharge section 193b may be arranged on either side of the central axis of the extension tube 190, respectively. In the present invention, microbubbles B' refer to bubbles that have a relatively small diameter compared to macrobubbles B, but are large enough to cause scattering and absorption effects during the propagation of ultrasound, thereby reducing the transmission efficiency of ultrasound.

[0119] The first discharge section 193a is located at the lower end of the extension pipe 190, that is, in the region adjacent to the communication section 191, and can perform the function of discharging relatively small microbubbles B' to the outside. The second discharge section 193b is located above the first discharge section 193a and can perform the function of discharging relatively large macrobubbles B.

[0120] According to one embodiment, the first discharge section 193a and the second discharge section 193b may be formed with different inner diameters to selectively discharge bubbles according to their size. The second discharge section 193b is located above the first discharge section 193a and is formed to discharge relatively large macrobubbles B, so it may be formed with a larger inner diameter than the first discharge section 193a.

[0121] The bubble discharge section 193 is not limited to the first discharge section 193a and the second discharge section 193b, and may branch into two or more from different positions on the extension pipe 190 as needed. For example, multiple bubble discharge sections 193 may be arranged in stages depending on the length of the extension pipe 190. Each bubble discharge section 193 may be formed with a different inner diameter and designed to discharge bubbles of different sizes in stages.

[0122] On the other hand, the extension pipe 190 may branch into multiple flow paths from the branching section 192, with some being formed as a bubble discharge section 193 and the remainder as an ultrasonic probe mounting section 124. An ultrasonic probe 141 is provided in each of the multiple openings of the ultrasonic probe mounting section 124, and the ultrasonic waves generated by each ultrasonic probe 141 overlap at the branching section 192, thereby improving the efficiency of ultrasonic peening.

[0123] For example, if the flow path branches into three from the branching section 192, the flow paths located on both sides may connect to the ultrasonic probe mounting section 124, and the flow path located in the center may constitute the bubble discharge section 193. The ultrasonic probe mounting section 124 may be formed with an upward inclination in the lateral direction relative to the branching section 192, and the bubble discharge section 193 may be located above the branching section 192 in a vertical direction.

[0124] Hereinafter, a method for peening a hollow spiral extension member E using an inner wall peening system 100 according to another embodiment of the present invention will be described with reference to Figure 13.

[0125] Figure 13 is a flowchart showing a method for peening a hollow spiral extension member E using an inner wall peening system 100 according to another embodiment of the present invention.

[0126] Referring to Figure 13, the peening method using the inner wall peening system 100 for the hollow spiral extension member includes the steps of: connecting the hollow spiral extension member E to the connecting pipe 120 (S101); filling the inside of the hollow spiral extension member E with an ultrasonic transmission medium M (S102); operating the ultrasonic generator 140 to perform peening (S103); recovering the ultrasonic transmission medium M into the medium tank 110 (S104); and separating the hollow spiral extension member E from the connecting pipe 120 (S105).

[0127] First, in the step of connecting the hollow spiral extension member E to the connecting pipe 120 (S101), as shown in Figures 1 and 2, one end 121 of the hollow spiral extension member E is connected to the opening 120a of the connecting pipe 120. At this time, the pressure inside the medium tank 110 and the connecting pipe 120 may be atmospheric pressure. In addition, a connecting tube 180 may be provided at one end of the connecting pipe, which is detachably connected to the lower end of the hollow spiral extension member. Here, the water level of the ultrasonic transmission medium M may be set lower than the opening 120a of the connecting tube 180 so that the ultrasonic transmission medium M does not overflow through the opening 120a of the connecting tube 180. The pressure inside the medium tank 110 and the connecting pipe 120 can be adjusted by a pressure regulator 130.

[0128] Next, in the step (S102) of filling the hollow spiral extension member E with ultrasonic transmission medium M, as shown in Figure 3, the pressure regulator 130 is controlled to fill the hollow spiral extension member E with ultrasonic transmission medium M.

[0129] Next, in the step of activating the ultrasonic generator 140 to perform peening (S103), as shown in Figure 4, the ultrasonic generator 140 is activated to perform ultrasonic cavitation peening on the inner wall of the hollow spiral extension member E.

[0130] Next, in the step of recovering the ultrasonic transmission medium M into the medium tank 110 (S104), as shown in Figure 5, the pressure regulator 130 is controlled to recover the ultrasonic transmission medium M filled inside the hollow spiral extension member E into the medium tank 110. For example, the ultrasonic transmission medium M can be recovered by stopping the operation of the pressure regulator 130, creating atmospheric pressure inside the medium tank 110 and the connecting pipe 120, and allowing gravity to discharge the ultrasonic transmission medium M from inside the hollow spiral extension member E. Alternatively, as another method of recovering the ultrasonic transmission medium M, the pressure regulator 130 can be used to create negative pressure inside the medium tank 110, thereby discharging the ultrasonic transmission medium M from inside the hollow spiral extension member E. In such a recovery method for the ultrasonic transmission medium M, no constraints arise regarding the relative height difference between the medium tank 110 and the connecting tube 180. In other words, when constructing the inner wall peening system 100 of the hollow spiral extension member, the relative height difference between the medium tank 110 and the connecting tube 180 can be freely set.

[0131] Finally, the step of separating the hollow spiral extension member E from the connecting pipe 120 (S105) involves removing one end of the hollow spiral extension member E connected to the opening 120a of the connecting pipe 120 from the connecting pipe 120, as shown in Figure 6.

[0132] On the other hand, the step of operating the ultrasonic generator 140 to perform peening (S103) may include the step of controlling the position of the pressure anti-node (S103a) and the step of performing peening with the positions of the pressure anti-nodes P1, P2, and P3 changed (S103b).

[0133] Step S103a, which controls the position of the pressure anti-nodes, involves controlling the pressure regulator 130 to change the positions of the pressure anti-nodes P1, P2, and P3, which are ultrasonic cavitation peening points. At this time, the positional changes of the pressure anti-nodes P1, P2, and P3 can be performed by controlling the pressure regulator 130 to adjust the filling water level of the ultrasonic transmission medium M filled in the hollow spiral extension member E.

[0134] Step S103b, in which peening is performed with the position of the pressure antinode changed, involves operating the ultrasonic generator 140 with the filling water level of the ultrasonic transmission medium M filled in the hollow spiral extension member E adjusted, thereby performing ultrasonic cavitation peening on the inner wall of the hollow spiral extension member E at the position of the pressure antinode.

[0135] This method of peening a hollow spiral extension member E using such an internal wall peening system 100 allows for the stable supply and recovery of an ultrasonic transmission medium M for ultrasonic cavitation peening inside the hollow spiral extension member E. By adjusting the filling water level of the ultrasonic transmission medium M while it is supplied inside the hollow spiral extension member E, the position of the pressure antinode, which is the peening point, is changed, thereby controlling the peening region of the inner wall of the hollow spiral extension member E. This method makes the peening work on the inner wall of the hollow spiral extension member E easier.

[0136] The above descriptions are merely illustrative and do not deviate from the scope and technical concept of the described embodiments. Various modifications can be made by persons with ordinary skill in the art to which the present invention pertains. The above embodiments can be implemented individually or in any combination. [Explanation of symbols]

[0137] 100, 200: Inner wall peening system for hollow spiral extension members 110: Media Tank 120: Connecting pipe 120a:Aperture 121:One end 122:Other end 123: Extension part 124: Ultrasonic probe mounting section 125: Tapered section 126: Recess 130: Pressure regulator 140: Ultrasonic generator 141: Ultrasound probe 141a: Probe tip 150: Sealing material 160: Cooler 170: Extension tube 180: Connecting tube 190: Extension tube 191:Communication part 192: Branching point 193: Bubble discharge section 193a: 1st discharge section 193b:Second discharge section 194: Separation membrane 210: Pressurizing jig E: Hollow spiral extension member M: Ultrasonic transmission medium P1, P2, P3: Pressure antinodes

Claims

1. A medium tank for containing an ultrasonic transmission medium, A connecting pipe having one end connected to a hollow spiral extension member and the other end connected to the medium tank, forming a flow path for the ultrasonic transmission medium from the medium tank to the inside of the hollow spiral extension member, A pressure regulator connected to the media tank and configured to control the flow of the ultrasonic transmission medium by adjusting the pressure inside the media tank, A system for peening the inner wall of a hollow spiral extension member, comprising: an ultrasonic generator provided in the connecting pipe and configured to generate ultrasonic waves from the inside of the connecting pipe toward the inside of the hollow spiral extension member so that ultrasonic cavitation peening is performed on the inner wall of the hollow spiral extension member with the inside of the hollow spiral extension member filled with the ultrasonic transmission medium.

2. The inner wall peening system for a hollow spiral extension member according to claim 1, characterized in that one end of the connecting pipe is provided with a connecting tube that is detachably connected to the lower end of the hollow spiral extension member.

3. The inner wall peening system for a hollow spiral extension member according to claim 2, characterized in that the ultrasonic probe that generates ultrasonic waves in the ultrasonic generator is positioned toward the opening of the connecting tube.

4. When the pressure is released while the ultrasonic transmission medium is filled inside the hollow spiral extension member due to the pressurization of the pressure regulator, the upper end of the medium tank is positioned lower than the connecting tube so that the ultrasonic transmission medium is completely discharged from the hollow spiral extension member by gravity. The inner wall peening system for a hollow spiral extension member according to claim 2, characterized in that the other end of the connecting pipe is connected to the bottom of the medium tank.

5. The inner wall peening system for a hollow helical extension member according to claim 1, further comprising an extension tube detachably coupled to the upper end of the hollow helical extension member and extending upward, such that the inside of the hollow helical extension member is completely filled with the ultrasonic transmission medium and stable position control of the pressure antinode is possible throughout the entire interior of the hollow helical extension member.

6. The inner wall peening system for a hollow spiral extension member according to claim 5, characterized in that the pressure regulator is configured to adjust the water level of the ultrasonic transmission medium in the extension tube by adjusting the pressure.

7. The hollow spiral extension member inner wall peening system according to claim 6, characterized in that the pressure regulator is configured to adjust the filling water level of the ultrasonic transmission medium so that ultrasonic cavitation peening is performed on the inner wall of the hollow spiral extension member when the water level of the ultrasonic transmission medium in the extension tube exceeds the end surface of the extension tube and the ultrasonic transmission medium leaks out to the outside.

8. In the ultrasonic generator, the ultrasonic probe that generates ultrasonic waves is configured to penetrate the connecting tube and be positioned inside the connecting tube, In the connecting pipe, the portion through which the ultrasonic probe passes is provided with a sealing member for sealing, A coating member is provided, which is made of a metal or non-metallic material and is formed to be coated on the surface of one end of the ultrasonic probe, so as to protect the surface of one end of the ultrasonic probe. The inner wall peening system for a hollow spiral extension member according to claim 1, characterized in that the sealing member is positioned at the pressure antinode of the ultrasonic probe where the vibration displacement becomes zero when ultrasonic waves are generated.

9. The aforementioned hollow spiral extension member is a hollow coil spring. The inner wall peening system for a hollow spiral extension member according to claim 1, further comprising a pressurizing jig configured to support the lower side of the hollow coil spring and apply downward pressure to the upper side so as to maintain the hollow coil spring in a compressed state during the ultrasonic cavitation peening process.

10. The present invention further includes an extension tube connected between the one end and the other end, having a plurality of openings, The inner wall peening system for a hollow spiral extension member according to claim 1, characterized in that an ultrasonic probe is attached to each of the plurality of openings.

11. The extension pipe includes a branching section that branches a communication section, which has a single opening communicating with the connecting pipe, into a plurality of openings. The inner wall peening system for a hollow spiral extension member according to claim 10, characterized in that the branching portion is located equidistant from each of the multiple openings such that ultrasonic waves incident on each of the multiple openings overlap at the branching portion.

12. The present invention further includes an extension pipe connected between the one end and the other end, The extension pipe is A connecting section that communicates with the aforementioned connecting pipe, An ultrasonic probe mounting section is provided, which forms a space for mounting an ultrasonic probe configured to generate ultrasonic waves toward the aforementioned communication section, The inner wall peening system for a hollow spiral extension member according to claim 1, characterized in that it includes a bubble discharge section extending in a branching manner from between the communication section and the ultrasonic probe mounting section, such that bubbles generated during peening with the ultrasonic probe rise and are discharged by buoyancy.

13. A method for peening a hollow spiral extension member using the inner wall peening system described in claim 1, The steps include connecting the lower end of the hollow spiral extension member to the connecting pipe, The steps include controlling the pressure regulator to fill the inside of the hollow spiral extension member with the ultrasonic transmission medium, The steps include: operating the ultrasonic generator to perform ultrasonic cavitation peening on the inner wall of the hollow spiral extension member; The steps include controlling the pressure regulator to change the position of the pressure antinode, which is the ultrasonic cavitation peening point, The steps include controlling the pressure regulator to recover the ultrasonic transmission medium filled inside the hollow spiral extension member into the medium tank, A method for peening a hollow helical extension member, comprising the step of separating the hollow helical extension member from the connecting pipe.

14. A medium supply unit is formed to supply and collect an ultrasonic transmission medium, A connecting pipe is connected to the hollow spiral extension member and the medium supply unit, respectively, and forms a flow path for the ultrasonic transmission medium from the medium supply unit to the inside of the hollow spiral extension member. An ultrasonic generator is provided such that an ultrasonic probe for generating ultrasonic waves is provided so as to penetrate the connecting tube, and the inside of the hollow spiral extension member is filled with the ultrasonic transmission medium, and ultrasonic waves are generated from the inside of the connecting tube toward the inside of the hollow spiral extension member so as to perform ultrasonic cavitation peening against the inner wall of the hollow spiral extension member. The connecting pipe includes a sealing member provided in the portion through which the ultrasonic probe penetrates, The inner wall peening system for a hollow spiral extension member is characterized in that the sealing member is positioned at the pressure antinode of the ultrasonic probe, where the vibration displacement becomes zero when ultrasonic waves are generated.

15. The connecting pipe is connected to the lower end of the hollow spiral extension member, The inner wall peening system for a hollow helical extension member according to claim 14, further comprising an extension tube detachably coupled to the upper end of the hollow helical extension member and extending upward, such that the inside of the hollow helical extension member is completely filled with the ultrasonic transmission medium and stable position control of the pressure antinode is possible throughout the entire interior of the hollow helical extension member.

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