Ultrasound examination equipment

Abstract

To provide an inspection device that can inspect a high-temperature inspection object while using transverse ultrasonic waves.SOLUTION: An ultrasonic inspection device comprises: a longitudinal ultrasonic sensor which transmits and receives longitudinal ultrasonic waves; and a metallic ultrasonic conversion unit having a polyhedron shape. The ultrasonic conversion unit includes: an output surface disposed facing an inspection object; an input surface on which the longitudinal ultrasonic sensor is disposed; and a conversion surface which inclines at a predetermined angle against a surface direction of the output surface. The conversion surface converts longitudinal ultrasonic waves input from the input surface into transverse ultrasonic waves and reflects the ultrasonic waves toward the output surface. Thermal conductivity of the ultrasonic conversion unit is lower than thermal conductivity of the inspection object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic inspection device.

Background Art

[0002] An inspection device that detects the solidification state of molten metal by utilizing the fact that shear wave ultrasonic waves do not penetrate the unfrozen portion of the molten metal is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An ultrasonic sensor that transmits shear wave ultrasonic waves may have lower heat resistance than an ultrasonic sensor that transmits longitudinal wave ultrasonic waves. Therefore, an inspection device that can inspect a high-temperature inspection target while utilizing shear wave ultrasonic waves is desired.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, an ultrasonic inspection device is provided. The ultrasonic inspection device includes a longitudinal wave ultrasonic sensor that transmits and receives longitudinal wave ultrasonic waves, and a metal ultrasonic conversion unit having a polyhedral shape, the ultrasonic conversion unit having an output surface disposed to face the inspection target, an input surface on which the longitudinal wave ultrasonic sensor is disposed, and a conversion surface inclined at a predetermined angle with respect to the surface direction of the output surface, the conversion surface converting the longitudinal wave ultrasonic waves input from the input surface into shear wave ultrasonic waves and reflecting them toward the output surface. The heat conductivity of the ultrasonic conversion unit is lower than the heat conductivity of the inspection target. According to this embodiment of the ultrasonic inspection apparatus, by making the thermal conductivity of the ultrasonic converter lower than that of the object being inspected, heat transfer from the object being inspected through the ultrasonic converter can be suppressed or prevented. Therefore, an inspection apparatus capable of inspecting high-temperature objects while utilizing transverse wave ultrasound can be obtained. (2) An ultrasonic inspection apparatus of the above form, wherein the ultrasonic converter is defined as the acoustic impedance obtained by multiplying the density of an object by the velocity of sound, and the ratio of the acoustic impedance of the object to be inspected to the acoustic impedance of the ultrasonic converter may be 0.5 ± 10% or 2.0 ± 10%. This type of ultrasonic inspection device allows for a good balance between the transmission and reflection of transverse ultrasonic waves at the interface between the object being inspected and the ultrasonic converter, thereby improving the detection accuracy of reflected waves by the ultrasonic inspection device. (3) An ultrasonic inspection apparatus of the above form, wherein the thermal expansion coefficient of the ultrasonic conversion unit may be smaller than the thermal expansion coefficient of the object to be inspected. This type of ultrasonic inspection device can suppress or prevent deformation of the ultrasonic conversion unit due to heat transfer from the object being inspected. (4) An ultrasonic inspection apparatus of the above form, wherein the ultrasonic conversion unit may be made of Ti-6Al-4V alloy. With this form of ultrasonic inspection apparatus, an ultrasonic converter can be obtained by a simple method using known materials. (5) An ultrasonic inspection apparatus of the above form, wherein the object to be inspected may include a mold having an internal space for forming a molded product and a molding material flowing into the internal space. This type of ultrasonic inspection device makes it possible to obtain an ultrasonic inspection device that can acquire information about the molding material inside a mold used in a molding machine or the like. This disclosure can also be implemented in various forms other than ultrasonic inspection devices. For example, it can be implemented in the form of an ultrasonic inspection method, a method for manufacturing molded products, a molding machine, a control method for ultrasonic inspection devices and molding machines, a computer program that implements the control method, a non-temporary recording medium that stores the computer program, etc. [Brief explanation of the drawing]

[0007] [Figure 1] An explanatory diagram showing the configuration of an ultrasound examination system. [Figure 2] An explanatory diagram showing the schematic configuration of the ultrasonic conversion unit. [Figure 3] An explanatory diagram showing examples of physical properties referenced in the fabrication of the ultrasonic converter. [Figure 4] An explanatory diagram showing the first experimental results obtained using an ultrasound imaging device. [Figure 5] An explanatory diagram showing the second experimental result obtained using an ultrasound examination device. [Modes for carrying out the invention]

[0008] A. First Embodiment: Figure 1 is an explanatory diagram showing the configuration of the ultrasonic inspection system 100. The ultrasonic inspection system 100 comprises an ultrasonic inspection device 80 and a control device 90 as a first embodiment of the present disclosure. The ultrasonic inspection system 100 is used by attaching the ultrasonic inspection device 80 to a mold 50, which is provided in a molding machine such as a die-casting machine. A "molding machine" is a device that manufactures molded products by injecting a molding material 54 into the inside of the mold 50 and allowing it to solidify. A "molding material" is, for example, a metal material before solidification, which is in a liquid or solid-liquid state. The metal material before solidification is also called "molten metal". Metal materials include various materials such as aluminum, aluminum alloys, zinc alloys, magnesium alloys, and copper alloys. In this embodiment, aluminum is used as the metal material, and the temperature of the molten metal is approximately 700°C. In addition to die-casting machines, molding machines may include various other molding machines, such as injection molding machines that use resin materials as molding materials.

[0009] The mold 50 can be formed using, for example, alloy tool steel. In this embodiment, the mold 50 is formed using SKD61 (Japanese Industrial Standard JIS G 4404:2015 alloy tool steel). The mold 50 has an outer wall E1 for mounting the ultrasonic inspection device 80 of the ultrasonic inspection system 100 and an inner wall E2 that defines the internal space CV. A release agent 52 is applied to the inner wall E2 of the mold 50. The mold 50 can be opened and closed by a clamping device (not shown). Inside the mold 50, which is closed by the clamping device, an internal space CV with substantially the same shape as the molded product is formed. The internal space CV is also called a cavity. Unsolidified metal material is injected and filled into the internal space CV of the mold 50 by an injection device (not shown). The unsolidified molding material 54 filled into the internal space CV is cooled by heat being absorbed by the mold 50, etc., and solidifies. As a result, a molded product is formed.

[0010] In this embodiment, the objects to be inspected include the mold 50, the molding material 54 present in the internal space CV of the mold 50, and the release agent 52 present in the internal space CV of the mold 50. The ultrasonic inspection device 80 is not limited to the example of being used for the mold and molding material, but may also be used to acquire information about any structure and the internal state of that structure, such as the state of the oil or fuel inside a cylinder block, and their temperatures.

[0011] The ultrasonic inspection apparatus 80 comprises an adhesive layer 81, an ultrasonic converter 82, a longitudinal wave ultrasonic sensor 84, and a high-speed AD converter 86. The adhesive layer 81 adheres the mold 50 to the ultrasonic inspection apparatus 80. Silver paste or a thin metal film can be used as the adhesive layer 81. The mold 50 may be fixed to the ultrasonic inspection apparatus 80 by bolts or the like, either in place of or together with the adhesive layer 81. A coupling medium may be applied between the ultrasonic converter 82 and the ultrasonic inspection apparatus 80 to improve ultrasonic transmission at the contact surface between the ultrasonic converter 82 and the longitudinal wave ultrasonic sensor 84. As the coupling medium, for example, silver paste or a thin metal film such as gold can be used, and if the temperature of the contact surface between the ultrasonic converter 82 and the longitudinal wave ultrasonic sensor 84 is sufficiently low, water or glycerin can be used.

[0012] The longitudinal ultrasonic sensor 84 is a probe that utilizes a piezoelectric element and transmits and receives longitudinal ultrasonic waves. "Longitudinal ultrasonic waves" are ultrasonic waves in which the medium vibrates in the same direction as the propagation direction, while "transverse ultrasonic waves" are ultrasonic waves in which the medium vibrates perpendicular to the propagation direction. From the viewpoint of using the longitudinal ultrasonic sensor 84 for inspecting high-temperature inspection targets such as molds 50, it is preferable that it has high heat resistance. In this embodiment, the heat resistance temperature of the longitudinal ultrasonic sensor 84 is about 500°C, which is lower than the temperature of the molten metal. The transverse ultrasonic sensor for transmitting transverse ultrasonic waves has a heat resistance temperature of, for example, about 120°C, which is generally lower than the heat resistance temperature of the longitudinal ultrasonic sensor.

[0013] As described later, the ultrasonic converter 82 is a metal structure having a polyhedral shape. A longitudinal wave ultrasonic sensor 84 is attached to the ultrasonic converter 82. The ultrasonic converter 82 converts the longitudinal wave ultrasonic waves emitted from the longitudinal wave ultrasonic sensor 84 into transverse wave ultrasonic waves and outputs the converted transverse wave ultrasonic waves to the object to be inspected. In addition, the ultrasonic converter 82 avoids the longitudinal wave ultrasonic sensor 84 being directly attached to the object to be inspected, and suppresses or prevents direct heat transfer from the object to the longitudinal wave ultrasonic sensor 84.

[0014] The ultrasonic conversion unit 82 has three surfaces: an input surface S1, an output surface S2, and a conversion surface S3. The input surface S1 is the surface to which the longitudinal wave ultrasonic sensor 84 is attached, and longitudinal ultrasonic waves are input from the longitudinal wave ultrasonic sensor 84. From the perspective of suppressing the exposure of the longitudinal wave ultrasonic sensor 84 to a high-temperature environment, it is preferable that the longitudinal wave ultrasonic sensor 84 be attached at a position separated from the molding material 54 and the mold 50.

[0015] The output surface S2 is the surface arranged to face the mold 50. "Arranged to face the mold 50" includes a state of facing in contact with the mold 50 and a state of facing in contact with the mold 50 through a medium such as an adhesive layer 81. The conversion surface S3 converts the longitudinal ultrasonic waves input from the input surface S1 into shear ultrasonic waves and reflects them toward the output surface S2. The three surfaces of the input surface S1, the output surface S2, and the conversion surface S3 are not limited to being flat surfaces and may be curved surfaces on the premise of having each function. However, from the perspective of smoothly propagating ultrasonic waves at the interface between objects, it is preferable that they be flat surfaces.

[0016] As shown by arrow LW1 in Figure 1, longitudinal ultrasonic waves transmitted from the longitudinal ultrasonic sensor 84 to the ultrasonic converter 82 via the input surface S1 propagate toward the conversion surface S3. As shown by arrow SW1, when the longitudinal ultrasonic waves are reflected at the conversion surface S3, they are converted into transverse ultrasonic waves and propagate toward the output surface S2. A portion of the transverse ultrasonic waves that propagate toward the output surface S2 are reflected by the outer wall E1 and propagate toward the conversion surface S3. As shown by arrow LW2, the transverse ultrasonic waves reflected by the outer wall E1 are reflected at the conversion surface S3 and converted into longitudinal ultrasonic waves, which are received by the longitudinal ultrasonic sensor 84. As shown by arrow SW2, the transverse ultrasonic waves that are not reflected by the outer wall E1 and are input to the mold 50 are reflected by the inner wall E2, the release agent 52, or the molding material 54. The transverse ultrasonic waves reflected by the inner wall E2, etc., propagate through the mold 50 and are input to the ultrasonic converter 82, and propagate toward the conversion surface S3. As indicated by arrow LW2, the transverse ultrasonic waves reflected at the conversion surface S3 are converted into longitudinal ultrasonic waves and received by the longitudinal ultrasonic sensor 84. In this way, the ultrasonic inspection device 80 can convert longitudinal ultrasonic waves to transverse ultrasonic waves via the ultrasonic conversion unit 82, and can perform inspections using transverse ultrasonic waves with the longitudinal ultrasonic sensor 84.

[0017] The high-speed AD converter 86 receives an analog voltage signal corresponding to the waveform of the longitudinal ultrasonic waves output from the longitudinal ultrasonic sensor 84. The high-speed AD converter 86 converts the input analog voltage signal into a digital signal and outputs it to the control device 90. The high-speed AD converter 86 may be provided in the longitudinal ultrasonic sensor 84 or in the control device 90.

[0018] The control device 90 is a microcomputer including a microprocessor that executes logical operations and memories such as a ROM and a RAM. By executing a program pre-stored in the memory, the microprocessor can execute the functions of each part provided in the present embodiment. In the present embodiment, by executing the program stored in the memory, the microprocessor functions as the propagation time calculation unit 92 and the information acquisition unit 94. The control device 90 may further control the operations of each part of a die casting machine such as the mold 50. Part or all of the functions of each part such as the propagation time calculation unit 92 and the information acquisition unit 94 may be realized by a hardware circuit. The propagation time calculation unit 92 and the information acquisition unit 94 may be provided in the high-speed AD converter 86.

[0019] The propagation time calculation unit 92 calculates the propagation time from when the longitudinal wave ultrasonic sensor 84 transmits longitudinal waves until the longitudinal waves as reflected waves are detected. The information acquisition unit 94 acquires information regarding the inspection target using the propagation time of the ultrasonic waves acquired by the propagation time calculation unit 92. For example, the information acquisition unit 94 acquires the temperature distribution of the inspection target based on a theoretical formula using the propagation time of the ultrasonic waves and physical property values regarding the inspection target including the thermal conductivity of the inspection target. As the theoretical formula for calculating the temperature distribution, for example, the theoretical formula disclosed in Japanese Patent Application Laid-Open No. 2008-70340 can be used. Instead of the theoretical formula, the information acquisition unit 94 may use a data table showing the relationship between the propagation time of the ultrasonic waves and the temperature of the inspection target. The information acquired by the information acquisition unit 94 is not limited to the temperature distribution of the inspection target, and may include the progress of solidification of the material inside the inspection target, the presence or absence of an object contacting the inner wall E2 of the mold 50, and the presence or absence of the Leidenfrost phenomenon in the mold 50. The Leidenfrost phenomenon means a phenomenon in which droplets evaporate on a solid surface at a temperature higher than its saturation temperature.

[0020] The method for manufacturing the ultrasonic converter 82 will be explained using Figures 2 and 3. Figure 2 is an explanatory diagram showing the schematic configuration of the ultrasonic converter 82. In the example in Figure 2, the ultrasonic converter 82 has the external shape of a roughly triangular prism with an upper surface ST and a lower surface SB of a right triangle where the angle θ between the output surface S2 and the conversion surface S3 is set. The ultrasonic converter 82 can be formed, for example, by molding a metal material using a mold or by cutting a metal material. In this embodiment, the width WD is set to 50.0 mm, the depth LG to 47.4 mm, and the height HT to 24.0 mm. However, the dimensions of each side are not limited to these and may be set arbitrarily. Note that the input surface S1, the output surface S2, and the conversion surface S3 do not have to be connected to each other. The shape of the ultrasonic converter 82 is not limited to a triangular prism, but may have any polyhedron shape having three surfaces: the input surface S1, the output surface S2, and the conversion surface S3.

[0021] A longitudinal wave ultrasonic sensor 84 is attached to a portion of the input surface S1, specifically to a region SA. The propagation direction of the longitudinal wave ultrasonic waves from the longitudinal wave ultrasonic sensor 84 is set to be perpendicular to the plane direction of the input surface S1.

[0022] The angle θ shown in Figure 2 is defined by the input surface S1 and the conversion surface S3. The angle θ is set so that the input longitudinal ultrasonic waves can be converted to transverse ultrasonic waves, and the propagation direction of the converted transverse ultrasonic waves is perpendicular to the plane direction of S3. In this embodiment, it was calculated by the following equation (1).

[0023]

number

[0024] The longitudinal and transverse wave speeds used in equation (1) above were measured values ​​of the material before processing of the ultrasonic converter 82 in order to suppress the influence of individual differences in the material. In this embodiment, as will be described later, Ti-6Al-4V (JIS Class 60) was used as the material for the ultrasonic converter 82, and the measured longitudinal wave speed was 6277.7 m / s, and the measured transverse wave speed was 3175.5 m / s. The angle θ was set to 26.832 degrees, which was derived from these measured values ​​and equation (1). In addition to the measured values, other values ​​such as known material properties may be used for the longitudinal and transverse wave speeds.

[0025] Figure 3 is an explanatory diagram showing an example of physical properties referenced in the fabrication of the ultrasonic converter 82. The table in Figure 3 shows the type of metal material and the physical properties of each metal material. The physical properties of each metal material are known values, and in this embodiment, we referred to the Japan Society of Mechanical Engineers (ed.) "Handbook of Mechanical Engineering, Combined Edition β. Design Edition". Note that each physical property value is shown at room temperature, but it is not limited to this, and the temperature of the operating environment may also be used. In Figure 3, the numerical values ​​that will be of focus in the following explanation are underlined to facilitate understanding of the technology.

[0026] In the section on metal material types, the leftmost section shows SKD61, the material of the mold 50 being inspected, for comparison. To the right of that, examples of metal materials selected as candidates for the ultrasonic converter 82 are shown. The following conditions were considered when selecting the material for the ultrasonic converter 82. (1) The ability to suppress or prevent heat transfer from the object being inspected to the longitudinal wave ultrasonic sensor 84. (2) The deformation of the ultrasonic converter 82 due to heat transfer from the object being inspected can be suppressed or prevented. (3) The material must have a good balance between the transmission and reflection of transverse ultrasonic waves at the interface between the object to be inspected and the ultrasonic converter 82.

[0027] To satisfy the above condition (1), it is preferable to use a material with low thermal conductivity. In this embodiment, a material having a lower thermal conductivity than the material to be inspected (SKD61 in this embodiment) was selected. In the example in Figure 3, the materials with lower thermal conductivity than SKD61 are stainless steel (SUS304) and Ti-6Al-4V. "Ti-6Al-4V" is an α+β type titanium alloy, a titanium alloy in which 6% aluminum and 4% vanadium are added to titanium by mass fraction. In this disclosure, Ti-6Al-4V is also referred to as "64 titanium". However, the thermal conductivity of the ultrasonic conversion unit 82 is not limited to being lower than the thermal conductivity of the material to be inspected; for example, it may be 100 (W / m·K) or less, provided that heat transfer from the material to be inspected to the longitudinal ultrasonic sensor 84 is suppressed. Furthermore, the thermal conductivity of the ultrasonic converter 82 is more preferably 50 (W / m·K) or less, from the viewpoint of sufficiently suppressing heat transfer from the object being inspected to the longitudinal ultrasonic sensor 84. The thermal conductivity of the ultrasonic converter 82 may be set lower than that of common metals such as carbon steel, chromium steel, and manganese steel.

[0028] In order to satisfy the above condition (2), it is preferable to use a material with a small coefficient of thermal expansion. In this embodiment, a material having a coefficient of thermal expansion smaller than that of SKD61 was selected. In the example in Figure 3, the only material with a smaller coefficient of thermal expansion than SKD61 is 64 titanium. However, in cases where the impact of deformation of the ultrasonic converter 82 on the detection accuracy of the longitudinal ultrasonic sensor 84 is small, the coefficient of thermal expansion of the ultrasonic converter 82 is 20(x10). -6 It may be set to 12 (x10) or less. Also, the thermal expansion coefficient of the ultrasonic converter 82 is set to 12 (x10) or less from the viewpoint of further reducing the influence of deformation of the ultrasonic converter 82 on the detection accuracy of the longitudinal wave ultrasonic sensor 84. -6 It is more preferable that the coefficient of thermal expansion of the ultrasonic converter 82 be less than or equal to / K. The coefficient of thermal expansion of the ultrasonic converter 82 may be set lower than the thermal conductivity of common metals such as carbon steel, chromium steel, and manganese steel.

[0029] To satisfy the above condition (3), it is preferable that there is a suitable difference between the transverse acoustic impedance of the material to be inspected (SKD61) and the transverse acoustic impedance of the material of the ultrasonic converter 82. "Acoustic impedance" refers to a physical property value obtained by multiplying the density of an object by the speed of sound. If the difference in transverse acoustic impedance between the material to be inspected and the ultrasonic converter 82 is large, the ultrasonic waves may be more easily reflected and less easily transmitted at the surface of the material to be inspected (outer wall E1 in the example of Figure 1). If the difference in transverse acoustic impedance is small, the ultrasonic waves may be more easily transmitted to the material to be inspected but less easily reflected. In this embodiment, it has been experimentally obtained through simulation that a good balance between reflection and transmission of transverse ultrasonic waves can be obtained when the ratio of transverse acoustic impedances is about 0.5 or 2.0. The ratio of transverse acoustic impedances can be set to 0.5 ± 10% or 2.0 ± 10% to allow for variations in physical properties and measurement errors for each material. In the example shown in Figure 3, the only material whose transverse acoustic impedance ratio falls within 2.0 ± 10% is titanium 64. As described above, in this embodiment, titanium 64 was selected as the material that satisfies all of the above conditions (1)-(3) for the ultrasonic conversion unit 82.

[0030] The characteristics of the fabricated ultrasonic converter 82 will be explained using Figures 4 and 5. Figure 4 is an explanatory diagram showing the first experimental results obtained using the ultrasonic inspection device 80 with the fabricated ultrasonic converter 82. The horizontal axis of Figure 4 shows the elapsed time (in microseconds) from the time when the longitudinal ultrasonic wave was emitted, and the vertical axis shows the reflected wave (in arbitrary units). The reflected wave W1 shown in Figure 4 shows the ultrasonic wave reflected at the interface between the mold 50 and the ultrasonic converter 82, i.e., the outer wall E1 (in the example of Figure 1, the ultrasonic wave indicated by arrow SW1). The reflected wave W2 shows the ultrasonic wave that penetrated the mold 50 and was reflected at the inner wall E2 (in the example of Figure 1, the ultrasonic wave indicated by arrow SW2).

[0031] For the information acquisition unit 94 to acquire information about the object being inspected, such as the propagation time of transverse ultrasonic waves and the temperature distribution of the mold 50, it is preferable that the reflected waves W1 and W2 have sufficient amplitude or intensity. As can be seen from the detection results shown in Figure 4, it can be understood that the reflected waves W1 and W2 have sufficient amplitude. The reflected wave W3 represents the ultrasonic waves that traveled back and forth twice within the ultrasonic conversion unit 82, then passed through the mold 50 and were reflected by the inner wall E2. The reflected wave W4 represents the ultrasonic waves that traveled back and forth twice within the mold 50 after being converted into transverse ultrasonic waves within the ultrasonic conversion unit 82.

[0032] Figure 5 is an explanatory diagram showing the second experimental results obtained using the ultrasonic inspection apparatus 80 with the fabricated ultrasonic converter 82. The horizontal axis is the time axis, and the vertical axis on the right side of the graph shows the propagation time of longitudinal ultrasonic waves and the propagation time of transverse ultrasonic waves. Note that "transverse ultrasonic wave propagation time" is a convenient expression and means the propagation time of ultrasonic waves before and after conversion using the ultrasonic converter 82. The vertical axis on the left side of the graph shows the surface temperature of the outer wall E1 as measured by a thermocouple. In this experiment, the mold 50 and ultrasonic inspection system 100 shown in Figure 1 were used, and a longitudinal ultrasonic sensor similar to the longitudinal ultrasonic sensor 84 was used for comparison. The longitudinal ultrasonic sensor 84 for comparison was directly attached to the outer wall E1 of the mold 50 without using the ultrasonic converter 82. In this experiment, molten metal at approximately 150°C, which is below the heat resistance temperature, was used to prevent failure of the longitudinal ultrasonic sensor for comparison. In this embodiment, a thermocouple for obtaining the surface temperature of the mold 50 is placed on the outer wall E1.

[0033] The control device 90 controls the longitudinal wave ultrasonic sensor 84 and the comparison longitudinal wave ultrasonic sensor to continuously emit longitudinal wave ultrasonic waves for a predetermined period, such as 100 seconds. The longitudinal wave ultrasonic sensor 84 and the comparison longitudinal wave ultrasonic sensor repeatedly detect reflected waves from the inner wall E2, and the control device 90 acquires the propagation time of each reflected wave. At time T1, approximately 30 seconds after the start of the experiment, molten metal is poured into the internal space CV of the mold 50.

[0034] Figure 5 shows graph GT, which illustrates the change in surface temperature of the outer wall E1 using a thermocouple; graph GL, which illustrates the change in propagation time of longitudinal ultrasonic waves acquired using a comparative longitudinal ultrasonic sensor; and graph GS, which illustrates the propagation time of ultrasonic waves acquired using the ultrasonic inspection device 80 of this embodiment. As graphs GL and GS show, the propagation time of each ultrasonic wave increases from the time T1 when the molten metal is introduced. Here, the comparative longitudinal ultrasonic wave shown in graph GL has a large change (noise) in the propagation time, including discontinuous values, as indicated by arrow P1. In contrast, the ultrasonic waves acquired using the ultrasonic inspection device 80 of this embodiment, shown in graph GS, show that there is no large noise in the propagation time and it changes stably. This indicates that the ultrasonic waves acquired using the ultrasonic inspection device 80 of this embodiment are stable and are not significantly affected by temperature changes or the Leidenfrost phenomenon caused by the high-temperature molten metal contacting the inner wall E2 of the mold 50. In other words, it indicates that the ultrasonic waves acquired using the ultrasonic inspection device 80 of this embodiment have performance comparable to that of transverse ultrasonic waves.

[0035] As described above, the ultrasonic inspection apparatus 80 of this embodiment includes an ultrasonic conversion unit 82 having an output surface S2 positioned facing the object to be inspected, an input surface S1 on which a longitudinal wave ultrasonic sensor 84 is positioned, and a conversion surface S3 that is inclined at a predetermined angle with respect to the surface direction of the output surface S2 to reflect the longitudinal wave ultrasonic waves input from the input surface S1 toward the output surface S2 and convert them into transverse wave ultrasonic waves. A longitudinal wave ultrasonic sensor 84, which has higher heat resistance than a transverse wave ultrasonic sensor, can be used, and the heat resistance of the inspection apparatus utilizing transverse wave ultrasonic waves can be increased. Since the longitudinal wave ultrasonic sensor 84 is positioned between it and the object to be inspected via the ultrasonic conversion unit 82, the ultrasonic conversion unit 82 can be separated from the object to be inspected, and heat transfer to the longitudinal wave ultrasonic sensor 84 can be suppressed or prevented. According to the ultrasonic inspection apparatus 80 of this embodiment, by making the thermal conductivity of the ultrasonic conversion unit 82 lower than the thermal conductivity of the object to be inspected, heat transfer from the object to be inspected via the ultrasonic conversion unit 82 can be suppressed or prevented.

[0036] In the ultrasonic inspection device 80 of this embodiment, the ratio of the acoustic impedance of the mold 50 to the acoustic impedance of the ultrasonic conversion unit 82 is 2.0 ± 10%. By providing a suitable difference between the transverse wave acoustic impedance of the mold 50 material (SKD61) and the transverse wave acoustic impedance of the material of the ultrasonic conversion unit 82, a good balance between the transmission and reflection of transverse wave ultrasonic waves at the interface between the mold 50 and the ultrasonic conversion unit 82 can be achieved, and the detection accuracy of reflected waves by the ultrasonic inspection device 80 can be increased.

[0037] In the ultrasonic inspection device 80 of this embodiment, the thermal expansion coefficient of the ultrasonic converter 82 is smaller than that of the mold 50. Therefore, deformation of the ultrasonic converter 82 due to heat transfer from the mold 50 can be suppressed or prevented, and the detection accuracy of reflected waves by the ultrasonic inspection device 80 can be increased.

[0038] In the ultrasonic inspection apparatus 80 of this embodiment, the ultrasonic converter 82 is made of Ti-6Al-4V alloy. The ultrasonic converter 82 can be manufactured by a simple method using known materials.

[0039] According to the ultrasonic inspection device 80 of this embodiment, the object to be inspected includes a mold 50 having an internal space CV for forming a molded product, and a molding material 54 flowing into the internal space CV. Therefore, an ultrasonic inspection device 80 can be obtained that can acquire information about the molding material 54 in a mold 50 used in a molding machine such as a die-casting machine or an injection molding machine.

[0040] B. Other embodiments: (B1) In the first embodiment described above, an example was shown in which titanium 64 was selected as the material for the ultrasonic converter 82 as a material that satisfies all of the following conditions: (1) thermal conductivity, (2) coefficient of thermal expansion, and (3) balance between transmission and reflection of transverse ultrasonic waves at the interface between the object to be inspected and the ultrasonic converter 82. In contrast, the material does not have to satisfy all the conditions, and at least (1) the material should have a lower thermal conductivity than the object to be inspected. In the example in Figure 3, for example, SUS304, which has a lower thermal conductivity than SKD61, may be selected. In addition to the above conditions (1) to (3), (4) good ultrasonic propagation characteristics in the ultrasonic converter 82 may also be considered. As a material with good ultrasonic propagation characteristics, for example, a material with a low ultrasonic attenuation rate can be used.

[0041] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0042] 50…Mold, 52…Release agent, 54…Molding material, 80…Ultrasonic inspection device, 81…Adhesive layer, 82…Ultrasonic conversion unit, 84…Longitudinal ultrasonic sensor, 86…High-speed AD converter, 90…Control device, 92…Propagation time calculation unit, 94…Information acquisition unit, 100…Ultrasonic inspection system, CV…Internal space, E1…Outer wall, E2…Inner wall, S1…Input surface, S2…Output surface, S3…Conversion surface, SB…Bottom surface, ST…Top surface

Claims

[Claim 1] An ultrasound examination device, A longitudinal wave ultrasonic sensor that transmits and receives longitudinal wave ultrasonic waves, A metal ultrasonic converter having a polyhedral shape, The output surface is positioned facing the object being inspected, The input surface on which the longitudinal wave ultrasonic sensor is arranged, The ultrasonic conversion unit includes a conversion surface that is inclined at a predetermined angle with respect to the surface direction of the output surface, and which converts longitudinal ultrasonic waves input from the input surface into transverse ultrasonic waves and reflects them toward the output surface, The thermal conductivity of the ultrasonic conversion unit is lower than the thermal conductivity of the object being inspected. The ultrasonic conversion unit is made of Ti-6Al-4V alloy. Ultrasound examination device.

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