Inspection method and ultrasonic inspection device
The method uses longitudinal and transverse ultrasonic waves to detect reflected waves, enabling the acquisition of multiple types of information about the inspection target, improving manufacturing conditions for molded products by determining the presence of objects and temperature distribution.
Patent Information
- Application Number
- JP2021008479
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-01-22
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2041-01-22
AI Technical Summary
Existing ultrasonic inspection methods lack the capability to acquire multiple types of information about an inspection target from outside the inspection target.
An inspection method using both longitudinal and transverse ultrasonic waves to detect reflected waves, determining first information such as the presence of an object in contact with the inner wall and second information such as temperature, allowing for the acquisition of temperature distribution and other properties of the inspection target.
Enables the acquisition of multiple types of information, including the presence of objects in contact with the inner wall and temperature distribution, facilitating more accurate manufacturing conditions for molded products.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present disclosure relates to an inspection method using ultrasound. [Background technology]
[0002] A technique is known in which ultrasonic waves are emitted from the outside of a mold with the cavity filled with molten metal toward the inside of the cavity, and the temperature and solid fraction of the molten metal are calculated based on the ultrasonic velocity calculated using multiple detected reflected waves (for example, Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2007-083275 A Summary of the Invention [Problem to be solved by the invention]
[0004] In an inspection method using ultrasound, there has been a demand for technology that can obtain a greater variety of information about an object to be inspected from outside the object to be inspected. [Means for solving the problem]
[0005] The present disclosure can be realized in the following forms. A first aspect of the present disclosure is an inspection method using ultrasonic waves, which transmits ultrasonic longitudinal waves to an inspection object including a mold having an internal space for forming a molded product and a molding material to be poured into the internal space, detects a reflected longitudinal wave that is a wave of the ultrasonic longitudinal waves reflected from the inspection object, and obtains at least one of a change in waveform of the reflected longitudinal wave and a propagation time of the ultrasonic longitudinal wave from transmission of the ultrasonic longitudinal wave to reception of the reflected longitudinal wave, and uses at least one of the change in waveform and the change in propagation time of the ultrasonic longitudinal wave to determine the interior of the mold. This inspection method involves determining first information including the presence or absence of the molding material abutting a wall, transmitting a shear wave ultrasonic wave to the object to be inspected, detecting a shear wave reflected wave that is a reflection of the shear wave ultrasonic wave from the object to be inspected, obtaining a propagation time of the shear wave ultrasonic wave from transmission to reception of the shear wave reflected wave, determining second information including temperature information of the object to be inspected using the obtained propagation time of the shear wave ultrasonic wave without using either a change in the waveform of the longitudinal wave ultrasonic wave or a change in the propagation time of the longitudinal wave ultrasonic wave, and changing the manufacturing conditions of the molded product using the first information and the second information.
[0006] (1) According to one embodiment of the present disclosure, there is provided an inspection method using ultrasonic waves, which includes transmitting a longitudinal ultrasonic wave to an inspection object capable of being filled with an object, detecting a longitudinal reflected wave that is a reflected wave of the longitudinal ultrasonic wave from the inspection object, acquiring at least one of a change in waveform of the longitudinal reflected wave and a propagation time of the longitudinal ultrasonic wave from the transmission of the longitudinal ultrasonic wave to the reception of the longitudinal reflected wave, determining first information including the presence or absence of the object abutting against an inner wall of the inspection object using at least one of the acquired change in waveform and the change in the propagation time of the longitudinal ultrasonic wave, transmitting a transverse ultrasonic wave to the inspection object, detecting a transverse reflected wave that is a reflected wave of the transverse ultrasonic wave from the inspection object, acquiring a propagation time of the transverse ultrasonic wave from the transmission of the transverse ultrasonic wave to the reception of the transverse reflected wave, and determining second information including temperature information of the inspection object using the acquired propagation time of the transverse ultrasonic wave. According to this inspection method, by acquiring at least one of the propagation time of the shear ultrasonic wave and the change in the waveform of the longitudinal reflected wave and the propagation time of the longitudinal ultrasonic wave, it is possible to acquire first information including the presence or absence of the object contacting the inner wall of the inspection object and second information including temperature information of the inspection object. Therefore, it is possible to acquire multiple types of information regarding the inspection object from outside the inspection object. (2) In the inspection method of the above aspect, the inspection object may include a mold having an internal space for forming a molded product, and a molding material flowing into the internal space. According to the inspection method of this form, it is possible to obtain multiple types of information regarding the state of the molding material in the mold used in the molding machine. (3) In the inspection method of the above aspect, the first information may further include a coating distribution of a release agent applied to an inner wall of the mold. According to the inspection method of this aspect, the application conditions of the release agent can be changed based on the state of the application distribution of the release agent during the production of the molded product. (4) In the inspection method of the above aspect, the first information may be used to observe a flow of the molding material in the internal space. According to this type of inspection method, the state in which the molding material flows within the mold when a molded product is manufactured can be grasped from outside the mold. (5) In the inspection method of the above aspect, a manufacturing condition of the molded product may be changed using the first information and the second information. According to this form of inspection method, the manufacturing conditions can be set based on the state of the molding material in the mold obtained during production, and the manufacturing conditions for the molded product can be made more optimal. The present disclosure can also be realized in various forms other than the inspection method using ultrasonic waves, for example, in the form of a manufacturing method for a molded product, a manufacturing apparatus for a molded product, an ultrasonic inspection apparatus, a control method for an ultrasonic inspection apparatus or a manufacturing apparatus for a molded product, a computer program for implementing the control method, a non-transitory recording medium on which the computer program is recorded, etc. [Brief description of the drawings]
[0007] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of an ultrasonic inspection device. [Diagram 2] FIG. 1 is an explanatory diagram showing an outline of a first experiment using an ultrasonic inspection device. [Diagram 3] 11 is a graph showing the results of changes in propagation time of longitudinal ultrasonic waves and shear ultrasonic waves obtained from a first experiment. [Figure 4] FIG. 11 is an explanatory diagram showing the results of the temperature distribution of the workpiece obtained by the first experiment. [Diagram 5] FIG. 4 is a flow diagram showing an inspection process using ultrasonic waves. [Figure 6] FIG. 13 is an explanatory diagram showing an outline of a second experiment using an ultrasonic inspection device. [Figure 7] 13 is a graph showing the results of changes in propagation time of longitudinal ultrasonic waves and shear ultrasonic waves obtained from a second experiment. [Figure 8] FIG. 11 is an explanatory diagram showing the results of the temperature distribution of the workpiece obtained by the second experiment. [Figure 9] FIG. 11 is an explanatory diagram showing the waveform of a transverse wave reflected from the bottom surface of a workpiece when no liquid water is attached. [Figure 10]FIG. 13 is an explanatory diagram showing the waveform of a shear wave reflected from the bottom surface of a workpiece with liquid water attached thereto. [Figure 11] FIG. 11 is an explanatory diagram showing the waveform of a longitudinal wave reflected from the bottom surface of a workpiece when no liquid water is attached. [Figure 12] FIG. 13 is an explanatory diagram showing the waveform of a longitudinal wave reflected from the bottom surface of a workpiece with liquid water attached thereto. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] A. First embodiment: FIG. 1 is an explanatory diagram showing a configuration of an ultrasonic inspection device 100 as a first embodiment of the present disclosure. The ultrasonic inspection device 100 includes an ultrasonic transmission / reception device 80 and a control device 90. The ultrasonic inspection device 100 is used, for example, by mounting the ultrasonic transmission / reception device 80 to a mold provided in a molding machine. A molding machine is a device that manufactures a molded product by injecting a molding material into a mold and solidifying the molding material in the mold. In this embodiment, the ultrasonic inspection device 100 is attached to a die-casting machine 200 as a molding machine. The molding material is, for example, a metal material before solidification that is in a liquid state or a solid-liquid coexistence state. The metal material before solidification is also called molten metal. The metal material includes various materials such as aluminum, aluminum alloy, zinc alloy, magnesium alloy, and copper alloy. In addition to a die-casting machine, the molding machine may include various molding machines such as an injection molding machine that uses a resin material as a molding material.
[0009] The die casting machine 200 includes a mold clamping device (not shown) including a mold 50, a mold release agent injection unit 60, and an injection unit 70. The mold 50 includes an outer wall for mounting an ultrasonic transmission / reception device 80 of the ultrasonic inspection device 100, and an inner wall of the mold 50 that defines an internal space CV. The mold clamping device opens, closes, and clamps the mold 50 under the control of a control device 90. The mold clamping device clamps the mold to form an internal space CV in the mold 50 that has substantially the same shape as the molded product. The internal space CV is also called a cavity. The mold release agent injection unit 60 applies a mold release agent 62 to the inner wall surface of the mold 50 under the control of the control device 90.
[0010] The injection device 70 injects and fills the internal space CV of the mold 50 with a metal material before solidification under the control of the control device 90. The injection device 70 has a sleeve 74 that communicates with the inside of the mold 50, a plunger 76 that can slide inside the sleeve 74, and an injection drive unit 72 that drives the plunger 76. When the mold clamping device completes clamping the mold 50, a supply device (not shown) supplies one shot of molding material PD from a supply port on the upper surface of the sleeve 74 into the sleeve 74. The plunger 76 slides inside the sleeve 74 toward the internal space CV, so that the molding material PD in the sleeve 74 is pushed out into the internal space CV of the mold 50. The molding material PD before solidification that has been filled into the internal space CV is cooled and solidified by the heat absorbed by the mold 50. As a result, a molded product is formed.
[0011] The ultrasonic transmitting / receiving device 80 includes a longitudinal wave ultrasonic sensor 82 that transmits and receives longitudinal wave ultrasonic waves, a shear wave ultrasonic sensor 84 that transmits and receives shear wave ultrasonic waves, contact media 81, 83, and a high-speed AD converter 86. The contact media 81, 83 improve ultrasonic transmission at the contact surfaces between the mold 50 and the longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84. As the contact media 81, 83, for example, water or glycerin can be used.
[0012] FIG. 1 shows a schematic diagram of the propagation direction DW of the shear wave ultrasonic wave and the longitudinal wave ultrasonic wave. The propagation direction DW is, for example, a direction substantially perpendicular to the surface of the outer wall of the mold 50 to which the longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84 are attached. The longitudinal wave ultrasonic wave is an ultrasonic wave in which a medium vibrates in the same direction as the propagation direction DW, and the shear wave ultrasonic wave is an ultrasonic wave in which a medium vibrates in a direction perpendicular to the propagation direction DW. As described later, the inspection object by the ultrasonic inspection device 100 of this embodiment includes the mold 50, the molding material PD present in the internal space CV of the mold 50, and the mold release agent 62 present in the internal space CV of the mold 50. The ultrasonic inspection device 100 may be used, for example, to obtain information such as the temperature of oil or fuel inside a cylinder block, and may be used for various inspection objects in which an object can be filled.
[0013] The longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84 are attached to the same surface of the outer wall of the mold 50. The ultrasonic inspection device 100 may include one each of the longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84, or may include a plurality of sensors. In this embodiment, from the viewpoint of widening the inspection range, a plurality of longitudinal wave ultrasonic sensors 82 and shear wave ultrasonic sensors 84 are attached to the same surface of the outer wall of the mold 50. The longitudinal wave ultrasonic sensor 82 transmits longitudinal ultrasonic waves toward the internal space CV of the mold 50. The longitudinal wave ultrasonic sensor 82 receives, for example, a longitudinal wave reflected wave that is a reflected wave reflected and returned from an end face E1 of the inner wall surface of the internal space CV of the mold 50 that is close to the position where the longitudinal wave ultrasonic sensor 82 is attached, or a longitudinal wave reflected wave that propagates through the molding material PD filled in the internal space CV and is reflected and returned from a bottom face E2 located on the opposite side of the end face E1 in the internal space CV.
[0014] The shear wave ultrasonic sensor 84 transmits shear wave ultrasonic waves toward the internal space CV of the mold 50. The shear wave ultrasonic sensor 84 receives reflected shear waves that are reflected back from an end face E1 of the inner wall surface in the internal space CV of the mold 50 that is close to the position where the shear wave ultrasonic sensor 84 is attached, and reflected shear waves that are reflected back from a bottom face E2.
[0015] Analog voltage signals having waveforms of reflected shear waves and reflected longitudinal waves are input to the high-speed AD converter 86 from the longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84. The high-speed AD converter 86 converts the input analog voltage signals into digital signals and outputs them to the control device 90. The high-speed AD converter 86 may be provided in the longitudinal wave ultrasonic sensor 82, the shear wave ultrasonic sensor 84, or the control device 90.
[0016] The control device 90 is a microcomputer equipped with a microprocessor that executes logical operations and memories such as ROM and RAM. The microprocessor controls the operation of each part of the die casting machine 200, such as the mold clamping device, the injection device 70, and the release agent injection unit 60, by executing a program stored in the memory. In this embodiment, the microprocessor functions as a propagation time acquisition unit 94, a second information acquisition unit 96, and a first information acquisition unit 98 by executing a program stored in the memory. Note that the functions of each part of the die casting machine 200, the propagation time acquisition unit 94, the second information acquisition unit 96, and the first information acquisition unit 98 may be partially or entirely realized by a hardware circuit.
[0017] The propagation time acquisition unit 94 calculates the propagation time of the longitudinal ultrasonic wave from when the longitudinal wave ultrasonic sensor 82 transmits the longitudinal ultrasonic wave to when it detects the reflected longitudinal wave, and the propagation time of the shear wave ultrasonic wave from when the shear wave ultrasonic sensor 84 transmits the shear wave to when it detects the first reflected shear wave. The propagation time acquisition unit 94 may be provided in the longitudinal wave ultrasonic sensor 82 or the shear wave ultrasonic sensor 84.
[0018] The second information acquiring unit 96 determines information about the inspection object using the propagation time of the shear wave ultrasonic wave acquired by the propagation time acquiring unit 94. Information about the inspection object obtained using the propagation time of the shear wave ultrasonic wave is also called "second information". In this embodiment, the second information acquiring unit 96 determines the temperature distribution of the inspection object as the second information based on a theoretical formula using the propagation time of the shear wave ultrasonic wave and known data about the inspection object including the thermal diffusivity of the inspection object. As a theoretical formula for calculating the temperature distribution, for example, the theoretical formula disclosed in JP 2008-70340 A can be used. The second information acquiring unit 96 may use a data table showing the relationship between the propagation time of the shear wave ultrasonic wave and the temperature of the inspection object. The second information is not limited to the temperature distribution of the inspection object, and may be various temperature information such as the temperature at an arbitrary position of the inspection object. The second information may include the progress of solidification of the material inside the inspection object.
[0019] The first information acquisition unit 98 determines the state of the inspection target using the propagation time of the longitudinal ultrasonic wave acquired by the propagation time acquisition unit 94. Information obtained using the change in the propagation time of the longitudinal ultrasonic wave is also called "first information". The first information includes, for example, the presence or absence of an object abutting the inner wall of the mold 50 that defines the internal space CV. The first information may include the presence or absence of the Leidenfrost phenomenon in the internal space CV, as described later. The Leidenfrost phenomenon refers to a phenomenon in which droplets evaporate on a solid surface at a temperature equal to or higher than their saturation temperature. Note that, like the second information acquisition unit 96, the first information acquisition unit 98 can calculate the temperature distribution of the inspection target based on a theoretical formula using the propagation time of the longitudinal ultrasonic wave and known data on the inspection target, including the thermal conductivity of the inspection target.
[0020] 2 to 4, a mechanism by which the ultrasonic inspection device 100 of this embodiment determines the first information using longitudinal ultrasonic waves will be described. FIG. 2 is an explanatory diagram showing an outline of a first experiment using the ultrasonic inspection device 100. In the first experiment, the ultrasonic inspection device 100 is attached to the surface E4 of the workpiece WK. The workpiece WK is SKD steel, which is also used as the material for the mold 50. The workpiece WK has a substantially rectangular external shape with a thickness of 30 mm in the propagation direction DW. The workpiece WK has a bottom surface E3 on the opposite side to the surface E4. An injector SY that injects liquid is disposed at a position facing the bottom surface E3 of the workpiece WK. The injector SY can inject liquid water WT1 onto the bottom surface E3 at any timing.
[0021] As shown in FIG. 2, a temperature detector 40 is attached to the workpiece WK. The temperature detector 40 is a temperature sensor having eight thermocouples T1 to T8. The temperature detection result by the temperature detector 40 is output to the control device 90. In the first experiment, the temperature detection result by the temperature detector 40 is used as a comparative example with the temperature distribution detection result using ultrasonic waves by the ultrasonic inspection device 100. The thermocouples T1 to T5 are arranged in order from the bottom surface E3 of the workpiece WK at intervals of about 1 mm, and the thermocouples T6 to T8 are arranged in order from the bottom surface E3 at intervals of about 10 mm. The thermocouple T8 is arranged on the surface E4.
[0022] 3 is a graph showing the results of changes in the propagation time of the longitudinal ultrasonic wave and the shear ultrasonic wave obtained by the first experiment. In the first experiment, the ultrasonic inspection device 100 causes the longitudinal ultrasonic sensor 82 and the shear ultrasonic sensor 84 to steadily transmit longitudinal ultrasonic wave and shear ultrasonic wave for a fixed period, such as 30 seconds. During this fixed period, the control device 90 detects the longitudinal reflected wave and the shear reflected wave from the bottom surface E3, and obtains the propagation time of the longitudinal ultrasonic wave and the propagation time of the shear ultrasonic wave. In the first experiment, liquid water WT1 from the injector SY is intermittently sprayed in multiple batches onto the bottom surface E3 of the workpiece WK, as described below.
[0023] The dashed line TTL1 shown in the graph of FIG. 3 indicates the change in the propagation time of the longitudinal ultrasonic wave. The solid line TTS1 indicates the change in the propagation time of the transverse ultrasonic wave. The solid line TT1 indicates the change in temperature near the bottom surface E3 obtained by the thermocouple T1. The horizontal axis of the graph of FIG. 3 is the time axis. The two vertical axes shown on the left side of the graph of FIG. 3 indicate the propagation time of the longitudinal ultrasonic wave and the propagation time of the transverse ultrasonic wave, respectively. In FIG. 3, from the viewpoint of facilitating the comparison between the propagation time of the longitudinal ultrasonic wave and the propagation time of the transverse ultrasonic wave, the dashed line TTL1 and the solid line TTS1 are arranged in positions close to each other by individually setting the scale of the propagation time of the longitudinal ultrasonic wave and the scale of the propagation time of the transverse ultrasonic wave. The vertical axis on the right side of the graph indicates the temperature of the thermocouple T1.
[0024] In the graph, the timing at which the liquid water WT1 is sprayed from the injector SY to the bottom surface E3 of the workpiece WK is shown typically by arrows SP1 to SP7. The propagation time of the transverse ultrasonic wave is substantially constant, as shown by the solid line TTS1 in FIG. 3. This shows that the propagation time of the transverse ultrasonic wave is not significantly affected by the adhesion of the liquid water WT1 to the bottom surface E3 of the workpiece WK. As shown by the dashed line TTL1 in FIG. 3, noise occurs in the propagation time of the longitudinal ultrasonic wave at the timings of the arrows SP1 to SP7, and the propagation time changes significantly compared to the propagation time of the transverse ultrasonic wave. This shows that the propagation time of the longitudinal ultrasonic wave is affected by the adhesion of the liquid water WT1 to the bottom surface E3 of the workpiece WK.
[0025] FIG. 4 is an explanatory diagram showing the results of the temperature distribution of the workpiece WK obtained by the first experiment. The vertical axis of the graph indicates the temperature, and the horizontal axis indicates the distance from the bottom surface E3 of the workpiece WK along the propagation direction DW. The position where the distance is 30 mm corresponds to the surface E4. The dashed line TPS1 shown in FIG. 4 indicates the results of the temperature distribution of the workpiece WK obtained using the propagation time of the shear ultrasonic wave. The dashed line TPL1 indicates the temperature distribution of the workpiece WK obtained using the propagation time of the longitudinal ultrasonic wave. The plot TP1 shown in FIG. 4 indicates the temperature at each position of the workpiece WK obtained from the thermocouples T1 to T8.
[0026] As shown by the dashed line TPS1 and the plot TP1 in FIG. 4, the temperature distribution obtained using the shear wave ultrasonic waves and the temperature distribution obtained from the thermocouples T1 to T8 are almost the same. This result shows that the temperature distribution obtained using the shear wave ultrasonic waves is stable and is not significantly affected by the adhesion of liquid water WT1 to the bottom surface E3 of the workpiece WK. As shown by the two-dot chain line TPL1, the temperature distribution obtained using the propagation time of the longitudinal wave ultrasonic waves has noise near the bottom surface E3 and is significantly different from the temperature distribution obtained using the propagation time of the shear wave ultrasonic waves. This result shows that the propagation time of the longitudinal wave ultrasonic waves is more easily affected by the adhesion of liquid water WT1 to the bottom surface E3 of the workpiece WK than the propagation time of the shear wave ultrasonic waves.
[0027] As shown in Figures 3 and 4, the results of the first experiment show that the longitudinal ultrasonic wave has a high sensitivity to the adhesion of other objects on the back surface of the object, i.e., the reflection position of the longitudinal ultrasonic wave. This is believed to be due to the fact that the longitudinal ultrasonic wave has a characteristic of easily propagating through liquid, while the shear ultrasonic wave has a characteristic of not easily propagating through liquid. Specifically, this is believed to be due to the fact that a part of the longitudinal ultrasonic wave that reaches the bottom surface E3 of the workpiece WK is transmitted to the liquid water WT1 attached to the bottom surface E3, thereby reducing the amplitude of the reflected longitudinal wave, and that the waveform of the reflected longitudinal wave is distorted by being repeatedly reflected multiple times in the liquid water WT1 attached to the bottom surface E3.
[0028] 5 is a flow diagram showing an inspection process using ultrasonic waves executed by the ultrasonic inspection device 100. This flow is started, for example, when the die-casting machine 200 starts manufacturing a molded product. This flow may be repeatedly executed for each manufacturing of a molded product.
[0029] In step S10, the control device 90 controls the mold clamping device and the injection device 70 to inject one shot of molding material PD into the internal space CV of the mold 50 that has been clamped. In step S20, a longitudinal ultrasonic wave is emitted from the longitudinal wave ultrasonic sensor 82 toward the internal space CV of the mold 50 that has been filled with the molding material PD, and a shear wave ultrasonic wave is emitted from the shear wave ultrasonic sensor 84. In this embodiment, in step S20, a longitudinal ultrasonic wave and a shear ultrasonic wave are emitted simultaneously.
[0030] In step S30, the longitudinal wave ultrasonic sensor 82 receives the reflected longitudinal wave reflected back from the end face E1 of the mold 50, and the shear wave ultrasonic sensor 84 receives the reflected shear wave. The high-speed AD converter 86 converts the analog voltage signals of the reflected longitudinal wave and the reflected shear wave input from the longitudinal wave ultrasonic sensor 82 and the shear wave ultrasonic sensor 84 into digital signals and outputs them to the control device 90. The propagation time acquisition unit 94 acquires the propagation time of the longitudinal ultrasonic wave and the propagation time of the shear ultrasonic wave using the input digital signals.
[0031] In step S40, the first information acquisition unit 98 determines the first information, and the second information acquisition unit 96 determines the second information. Specifically, the first information acquisition unit 98 detects a change (noise) in the propagation time of the longitudinal ultrasonic wave to determine the first information. The first information acquisition unit 98 can determine the presence or absence of a change (noise) in the propagation time of the longitudinal ultrasonic wave, for example, by determining whether or not the differential value of the propagation time of the longitudinal ultrasonic wave is greater than a predetermined threshold value. The first information acquisition unit 98 utilizes the fact that the longitudinal ultrasonic wave has high sensitivity to the presence or absence of the adhesion of the object FE to the end face E1 of the object FE, as shown in the results of the first experiment. In this embodiment, the first information acquisition unit 98 determines the presence or absence of a gap between the molding material PD, also called an air gap, and the mold 50 as the presence or absence of an object abutting against the inner wall of the mold 50. The first information acquisition unit 98 may acquire the application distribution of the release agent 62 adhering to the inner wall of the mold 50 before the mold 50 is filled with the molding material PD.
[0032] The second information acquiring unit 96 acquires the second information using the propagation time of the shear wave ultrasonic waves. As shown in the results of the first experiment, the second information acquiring unit 96 utilizes the fact that the shear wave ultrasonic waves can stably acquire the temperature distribution of the inspection object. In this embodiment, the second information acquiring unit 96 calculates the temperature distribution of the inspection object based on a theoretical formula using the propagation time of the shear wave ultrasonic waves and known data regarding the inspection object including the thermal diffusivity of the inspection object, and determines it as the second information. The flow from the transmission of the longitudinal wave ultrasonic waves to the determination of the first information in steps S20 to S40 and the flow from the transmission of the shear wave ultrasonic waves to the determination of the second information are not necessarily performed simultaneously. For example, the flow from the transmission of the longitudinal wave ultrasonic waves to the determination of the first information may be performed after the flow from the transmission of the longitudinal wave ultrasonic waves to the determination of the first information, or may be performed in any order such as the reverse order, and both flows may be performed in parallel after being started in any order.
[0033] In step S50, the control device 90 uses the first information determined by the first information acquisition unit 98 and the second information determined by the second information acquisition unit 96 to control each unit of the die-casting machine 200 and change the manufacturing conditions of the molded product. Specifically, the control device 90 adjusts the cooling period of the molding material PD by shortening or extending the clamping period of the mold 50 based on, for example, the temperature distribution of the molding material PD acquired by the second information acquisition unit 96. The control device 90 may adjust the flow rate and temperature of the coolant in the mold 50. The control device 90 may, for example, acquire the progress of solidification of the molding material PD from the temperature distribution of the molding material PD and adjust the operation of the ejector pin in the mold 50 and the mold opening timing of the mold 50.
[0034] The control device 90 further detects the presence or absence of an object abutting against the end surface E1 that defines the internal space CV of the mold 50 based on the first information determined by the first information acquisition unit 98. Specifically, the control device 90 detects, for example, an air gap between the molding material PD and the mold 50 using the first information as described above. When there are many air gaps, the control device 90 controls the injection device 70 to increase the injection pressure by the plunger 76 and adjust the filling speed of the molding material PD to improve the filling rate of the molding material PD into the internal space CV. When the control device 90 uses the first information to acquire the application distribution of the release agent 62 applied on the end surface E1, the control device 90 may control the release agent injection unit 60 to adjust the application amount of the release agent 62 into the internal space CV of the mold 50. For example, when the application amount of the release agent is insufficient, the control device 90 controls the release agent injection unit 60 to adjust the application amount of the release agent, the injection direction of the release agent, and the like while the mold 50 is in the open state.
[0035] The control device 90 further uses the first information obtained from the first information acquisition unit 98 to observe the flow of the molding material PD in the internal space CV, which is also called the flow of the molten metal. Specifically, the control device 90 uses a plurality of pieces of first information obtained from a plurality of longitudinal wave ultrasonic sensors 82 attached to the same surface of the outer wall of the mold 50. When the molding material PD is injected into the mold 50, the control device 90 acquires the presence or absence of the molding material PD abutting the internal space CV from each of the plurality of longitudinal wave ultrasonic sensors 82 arranged at different positions. The control device 90 acquires the result of mapping the presence or absence of the molding material PD based on the arrangement positions of the longitudinal wave ultrasonic sensors 82 as the observation result of the flow of the molten metal. The control device 90 acquires the observation result of the flow of the molten metal at every predetermined unit time, and controls the injection device 70 based on the observation result of the flow of the molten metal to adjust the injection pressure by the plunger 76 and the filling speed of the molding material PD, thereby adjusting the filling rate of the molding material PD in the internal space CV.
[0036] Another form of the first information acquired by the ultrasonic inspection device 100 of this embodiment will be described with reference to Figs. 6 to 8. Fig. 6 is an explanatory diagram showing an outline of a second experiment using the ultrasonic inspection device 100. The workpiece WK as the inspection target is the same as the workpiece WK used in the first experiment shown in Fig. 2. As in the first experiment, the temperature detector 40 is attached to the workpiece WK. The second experiment differs from the first experiment in that liquid water WT2 is attached to the bottom surface E3 of the workpiece WK, and then a high-temperature object FE is brought into contact with the bottom surface E3 with the liquid water WT2 attached thereto. In the second experiment, a rectangular piece of iron heated to about 500°C was used as the object FE.
[0037] FIG. 7 is a graph showing the results of the change in the propagation time of the longitudinal ultrasonic wave and the shear ultrasonic wave obtained by the second experiment. In the second experiment, the ultrasonic inspection device 100 causes the longitudinal ultrasonic sensor 82 and the shear ultrasonic sensor 84 to steadily transmit the longitudinal ultrasonic wave and the shear ultrasonic wave for a certain period, such as 80 seconds. The control device 90 detects the longitudinal reflected wave and the shear reflected wave from the bottom surface E3 during this certain period, and obtains the propagation time of the longitudinal ultrasonic wave and the propagation time of the shear ultrasonic wave. In the second experiment, liquid water WT2 is further attached to the bottom surface E3 of the workpiece WK at a timing of about 10 seconds after the start of the experiment, as indicated by arrows SP8 and SP9. At a timing TH 45 seconds after the start of the experiment, an object FE is brought into contact with the bottom surface E3 of the workpiece WK.
[0038] The dashed line TTL2 shown in the graph of FIG. 7 indicates the change in the propagation time of the longitudinal ultrasonic wave. The solid line TTS2 indicates the change in the propagation time of the transverse ultrasonic wave. The solid line TT2 indicates the change in temperature near the bottom surface E3 obtained by the thermocouple T1. The horizontal axis of the graph is the time axis. The vertical axis on the left side of the graph indicates the propagation time of the longitudinal ultrasonic wave and the propagation time of the transverse ultrasonic wave. The two vertical axes shown on the left side of the graph of FIG. 7 indicate the propagation time of the longitudinal ultrasonic wave and the propagation time of the transverse ultrasonic wave, respectively. In FIG. 7, from the viewpoint of facilitating the comparison between the propagation time of the longitudinal ultrasonic wave and the propagation time of the transverse ultrasonic wave, the dashed line TTL2 and the solid line TTS2 are arranged in positions close to each other by individually setting the scale of the propagation time of the longitudinal ultrasonic wave and the scale of the propagation time of the transverse ultrasonic wave. The vertical axis on the right side of the graph indicates the temperature of the thermocouple T1.
[0039] In the graph, the timing at which the liquid water WT2 is applied to the bottom surface E3 of the workpiece WK is shown typically by arrows SP8 and SP9. As shown by the solid line TTS2 in Fig. 7, the propagation time of the transverse ultrasonic wave is substantially constant, and it is understood that there is no effect of the liquid water WT2 being applied to the bottom surface E3 of the workpiece WK. As shown by the dashed line TTL2, the propagation time of the longitudinal ultrasonic wave changes significantly at the timing of the arrows SP8 and SP9.
[0040] As shown by the solid line TTS2 in FIG. 7, the propagation time of the transverse ultrasonic wave increases monotonically from the timing TH when the object FE contacts the bottom surface E3. As shown by the dashed line TTL2, the propagation time of the longitudinal ultrasonic wave increases from the timing TH. Here, the propagation time of the longitudinal ultrasonic wave has a large change (noise) including discontinuous values, as shown by the arrows LF1 and LF2. It is considered that the noise in the propagation time of the longitudinal ultrasonic wave shown by the arrows LF1 and LF2 is generated due to the influence of the Leidenfrost phenomenon in which the liquid water WT2 is evaporated instantly when the high-temperature object FE contacts the liquid water WT2. This result shows that the longitudinal ultrasonic wave has a higher sensitivity to the Leidenfrost phenomenon than the transverse ultrasonic wave. The first information acquisition unit 98 can detect the noise in the propagation time of the longitudinal ultrasonic wave by, for example, comparing the differential value of the propagation time of the longitudinal ultrasonic wave with a predetermined threshold value, and determine whether or not the Leidenfrost phenomenon occurs at the end surface E1 of the mold 50.
[0041] FIG. 8 is an explanatory diagram showing the results of the temperature distribution of the workpiece WK obtained by the second experiment. The vertical axis of the graph indicates the temperature, and the horizontal axis indicates the distance from the bottom surface E3 of the workpiece WK. The dashed line TPS2 shown in FIG. 8 indicates the results of the temperature distribution of the workpiece WK obtained using the propagation time of the transverse ultrasonic wave. The dashed line TPL2 indicates the temperature distribution of the workpiece WK obtained using the propagation time of the longitudinal ultrasonic wave. The plot TP2 shown in FIG. 8 indicates the temperature at each position of the workpiece WK obtained from the thermocouples T1 to T8.
[0042] As shown by the dashed line TPS2 and the plot TP2 in FIG. 8, the temperature distribution obtained using the shear wave ultrasonic wave and the temperature distribution obtained from the thermocouples T1 to T8 are almost the same. This result shows that the temperature distribution obtained using the shear wave ultrasonic wave is stable and is not significantly affected by the Leidenfrost phenomenon at the bottom surface E3 of the workpiece WK. As shown by the two-dot chain line TPL2, noise occurs in the temperature distribution obtained using the propagation time of the longitudinal wave ultrasonic wave, and the temperature distribution in the vicinity of the bottom surface E3 changes significantly. This result shows that the longitudinal wave ultrasonic wave has a higher sensitivity to the Leidenfrost phenomenon than the shear wave ultrasonic wave.
[0043] As shown by the results of the second experiment, the ultrasonic inspection device 100 utilizes the fact that longitudinal ultrasonic waves have high sensitivity to the occurrence of the Leidenfrost phenomenon at the end surface E1. By detecting the occurrence of the Leidenfrost phenomenon, for example, it is possible to detect the evaporation of the release agent 62 when applying the release agent 62 to the internal space CV of the mold 50. The evaporation of the release agent 62 occurs, for example, when the residual heat of the mold 50 after manufacturing a molded product is high. When the evaporation of the release agent 62 is confirmed, the control device 90 controls the release agent injection unit 60 and adjusts the application amount of the release agent and the injection position of the release agent to suppress a decrease in the application amount of the release agent 62 in the internal space CV. When the evaporation of the release agent is detected, the release agent may be changed to a release agent with a higher boiling point.
[0044] As described above, according to the ultrasonic inspection device 100 of this embodiment, the propagation time of the longitudinal reflected wave is used to obtain first information including the presence or absence of objects such as a release agent or molding material PD in contact with the end face E1 of the mold 50 and the occurrence or absence of the Leidenfrost phenomenon, and the propagation time of the shear ultrasonic wave is used to obtain second information including the temperature distribution of the molding material PD in the internal space CV of the mold 50 and the progress of solidification of the molding material PD. Therefore, multiple types of information regarding the molding material PD inside the mold 50 can be obtained from outside the mold 50.
[0045] According to the ultrasonic inspection device 100 of this embodiment, the inspection object includes the mold 50 and the molding material PD flowing into the internal space CV of the mold 50. Therefore, it is possible to obtain the ultrasonic inspection device 100 that can externally acquire multiple types of information related to the molding material PD in the mold 50 used in a molding machine such as the die-casting machine 200.
[0046] According to the ultrasonic inspection device 100 of this embodiment, the first information includes the application distribution of the release agent 62 applied to the end face E1 that defines the internal space CV of the die 50. By acquiring the application distribution of the release agent 62 from outside the die 50, it is possible to change the application conditions of the release agent 62 during the production of a molded product by the die casting machine 200, thereby reducing the variation in the application distribution of the release agent 62.
[0047] The ultrasonic inspection device 100 of this embodiment further observes the flow of the molding material PD in the internal space CV using the first information. Therefore, when a molded product is manufactured by the die-casting machine 200, the state in which the molding material PD flows within the die 50 can be grasped from the outside. Therefore, the state in which the molding material PD flows within the die 50 can be grasped more accurately than by a fluid simulation.
[0048] According to the ultrasonic inspection device 100 of this embodiment, the acquired first information and second information are further used to change the manufacturing conditions of the molded product by the die-casting machine 200. The manufacturing conditions can be set based on the state of the molding material PD in the die 50 acquired during production, and the manufacturing conditions of the molded product can be further optimized.
[0049] B. Other embodiments: (B1) In the above embodiment, as shown in Fig. 3 and Fig. 4, the ultrasonic inspection device 100 detects noise in the propagation time of the longitudinal ultrasonic wave and noise in the temperature distribution obtained using the propagation time of the longitudinal ultrasonic wave to determine the presence or absence of an object abutting the end face E1 that defines the internal space CV of the mold 50. Also, as shown in Fig. 7 and Fig. 8, the ultrasonic inspection device 100 detects noise in the propagation time of the longitudinal ultrasonic wave and noise in the temperature distribution obtained using the propagation time of the longitudinal ultrasonic wave to determine the presence or absence of the Leidenfrost phenomenon at the end face E1 of the mold 50. In contrast, the ultrasonic inspection device 100 may detect a change in the waveform of the reflected longitudinal wave to determine the presence or absence of an object abutting the end face E1 that defines the internal space CV of the mold 50 and the presence or absence of the Leidenfrost phenomenon.
[0050] Fig. 9 is an explanatory diagram showing the waveform of a shear wave reflected from the bottom surface E3 of the workpiece WK in a state where no liquid water WT1 is attached in the first experiment. Fig. 10 is an explanatory diagram showing the waveform of a shear wave reflected from the bottom surface E3 of the workpiece WK in a state where liquid water WT1 is attached in the first experiment. The waveforms shown in Fig. 9 and Fig. 10 are the results detected by the shear wave ultrasonic sensor 84. In Fig. 9 and Fig. 10, the horizontal axis represents the time axis, and the vertical axis represents the amplitude.
[0051] 9 and 10 show the difference SA1 and difference SA2 between the maximum and minimum amplitudes of the reflected shear wave. As shown in Fig. 9 and 10, the difference SA1 and the difference SA2 are approximately equal, and the waveforms of the reflected shear waves are approximately the same. This indicates that the ultrasonic shear wave is not significantly affected by the adhesion of liquid water WT1 to the bottom surface E3 of the workpiece WK.
[0052] Fig. 11 is an explanatory diagram showing the waveform of a longitudinal wave reflected from the bottom surface E3 of the workpiece WK in a state where no liquid water WT1 is attached in the first experiment. Fig. 12 is an explanatory diagram showing the waveform of a longitudinal wave reflected from the bottom surface E3 of the workpiece WK in a state where liquid water WT1 is attached in the first experiment. The waveforms shown in Fig. 11 and Fig. 12 are the results detected by the longitudinal wave ultrasonic sensor 82. In Fig. 11 and Fig. 12, the horizontal axis is the time axis, and the vertical axis is the amplitude.
[0053] As shown in Fig. 11, the longitudinal wave reflected from the bottom surface E3 of the workpiece WK in a state where liquid water WT1 is not attached has a first waveform LN11 and a second waveform LN12 that is detected after the first waveform LN11 and has a smaller amplitude than the first waveform LN11. Fig. 11 shows a difference LA1 between the maximum and minimum amplitude values of the first waveform LN11. As shown in Fig. 12, the longitudinal wave reflected from the bottom surface E3 of the workpiece WK in a state where liquid water WT1 is attached has a first waveform LN21 and a second waveform LN22 that is detected after the first waveform LN21 and has a smaller amplitude than the first waveform LN21. Fig. 12 shows a difference LA2 between the maximum and minimum amplitude values in the waveform of the longitudinal wave reflected.
[0054] The difference LA2 in the first waveform LN21 shown in Fig. 12 is smaller than the difference LA1 in the first waveform LN11 shown in Fig. 11. That is, it can be seen that the amplitude of the reflected longitudinal wave in the first waveform is smaller due to the influence of the liquid water WT1 adhering to the bottom surface E3 of the workpiece WK. This is considered to be due to the fact that, as described above, a portion of the ultrasonic longitudinal wave that reaches the bottom surface E3 of the workpiece WK is transmitted to the liquid water WT1 adhering to the bottom surface E3.
[0055] The amplitude of the second waveform LN22 shown in FIG. 12 is larger than the amplitude of the second waveform LN12 shown in FIG. 11. That is, it can be seen that the second waveform of the longitudinal reflected wave is distorted due to the influence of the liquid water WT1 adhering to the bottom surface E3 of the workpiece WK. This is considered to be due to the fact that a part of the longitudinal ultrasonic wave is repeatedly reflected multiple times in the liquid water WT1 adhering to the bottom surface E3, as described above. As described above, the presence or absence of an object abutting the end surface E1 defining the internal space CV of the mold 50 and the occurrence or absence of the Leidenfrost phenomenon can also be determined using a change in the waveform of the longitudinal reflected wave, such as the difference between the maximum and minimum values of the amplitude of the first waveform LN11 of the longitudinal reflected wave and the maximum and minimum values of the amplitude of the first waveform LN21 of the longitudinal reflected wave, or the presence or absence of the second waveform LN22, instead of or in addition to the propagation time of the longitudinal reflected wave.
[0056] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]
[0057] 40...temperature detector, 50...mold, 60...release agent injection unit, 62...release agent, 70...injection device, 72...injection drive unit, 74...sleeve, 76...plunger, 80...ultrasonic transmitter / receiver, 81, 83...coupling medium, 82...longitudinal wave ultrasonic sensor, 84...transverse wave ultrasonic sensor, 86...high-speed AD converter, 90...control device, 94...propagation time acquisition unit, 96...second information acquisition unit, 98...first information acquisition unit, 100...ultrasonic inspection device, 200...die casting machine, CV...internal space, DW...propagation direction, FE...object, PD...molding material, SY...injector, T1 to T8...thermocouple, WK...workpiece, WT1, WT2...liquid water
Claims
1. An inspection method using ultrasound, comprising: A longitudinal ultrasonic wave is transmitted to an inspection object including a mold having an internal space for forming a molded product and a molding material flowing into the internal space, and a longitudinal reflected wave that is a reflected wave of the longitudinal ultrasonic wave from the inspection object is detected, and at least one of a change in the waveform of the longitudinal reflected wave and a propagation time of the longitudinal ultrasonic wave from transmission of the longitudinal ultrasonic wave to reception of the longitudinal reflected wave is obtained; determining first information including the presence or absence of the molding material in contact with the inner wall of the mold using at least one of the acquired change in the waveform and the change in the propagation time of the longitudinal ultrasonic wave; Transmitting a shear wave ultrasonic wave to the inspection object, detecting a shear wave reflection wave that is a reflection wave of the shear wave ultrasonic wave from the inspection object, and acquiring a propagation time of the shear wave ultrasonic wave from transmission of the shear wave ultrasonic wave to reception of the shear wave reflection wave; determining second information including temperature information of the test object using the acquired propagation time of the shear ultrasonic wave without using either the change in the waveform of the longitudinal ultrasonic wave or the change in the propagation time of the longitudinal ultrasonic wave; changing the manufacturing conditions of the molded product using the first information and the second information; Testing method.
2. The inspection method according to claim 1 , wherein the first information further includes a distribution of a release agent applied to an inner wall of the mold.
3. The inspection method according to claim 1 or 2, further comprising observing a flow of the molding material in the internal space using the first information.
4. An ultrasonic inspection device using ultrasonic waves, a longitudinal wave ultrasonic sensor for transmitting longitudinal wave ultrasonic waves to an inspection object including a mold having an internal space for forming a molded product and a molding material flowing into the internal space, and receiving a longitudinal wave reflected from the inspection object; a shear wave ultrasonic sensor for transmitting a shear wave ultrasonic wave to the inspection object and receiving a shear wave reflected from the inspection object; a control device that determines first information including the presence or absence of an object abutting against an inner wall of the mold using at least one of a change in the waveform of the reflected longitudinal wave and a propagation time from transmission of the longitudinal ultrasonic wave to reception of the reflected longitudinal wave corresponding to the longitudinal ultrasonic wave, and determines second information including temperature information of the inspection object using a propagation time from transmission of the transverse ultrasonic wave to reception of the reflected transverse wave corresponding to the transverse ultrasonic wave without using either a change in the waveform of the longitudinal ultrasonic wave or a change in the propagation time of the longitudinal ultrasonic wave, The control device changes the manufacturing conditions of the molded product using the first information and the second information. Ultrasound testing equipment.
Citation Information
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