Molding material behavior detection device

Abstract

To provide a molding material behavior detection device capable of improving detection accuracy of molding material behavior within a cavity.SOLUTION: A molding material behavior detection device according to the present invention comprises a waveform generation unit, an ultrasonic sensor, and an output processing unit. The ultrasonic sensor is a propagation medium including a first portion located outside a mold and a second portion located in a through hole penetrating the mold, which includes: a propagation body capable of propagating a guided wave extending longitudinally from the first part to the second part; a transmission coil, located in the first portion, which propagates the guided wave through the propagation body in response to an input voltage from the waveform generation unit; and a reception coil, located in the first portion, which generates an output voltage waveform in response to the guided wave propagating within the propagation body. The output processing unit processes the output voltage waveform to generate a detection result. The second portion includes a tip surface exposed to a cavity, and the tip surface is located on the same plane as the inner surface of the mold, or is located inside the cavity relative to the inner surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molding material behavior detection device. [Background technology]

[0002] Molded products made by casting or injection molding are made by filling the cavity of a metal mold, sand mold, or other mold with molten molding material (metal material, resin material, or ceramic material). The molded product is produced when the filled molding material solidifies and is then removed from the mold.

[0003] Simulations are sometimes performed to confirm the behavior of molding materials within a mold cavity. Appropriate adjustment of parameters is effective for improving the accuracy of the simulation. To achieve this, it is effective to understand in advance the behavior of the molding material, including the flow of the molten molding material within the cavity and the timing of its solidification. For example, methods for detecting the solidification process and temperature change of molding materials are known (see Patent Documents 1 and 2).

[0004] However, the ultrasonic transducers used for detection in these documents are attached to the outside of the mold, which makes it difficult to improve the detection accuracy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-74499 [Patent Document 2] Special Publication No. 2007-212358 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above points, and has an object to provide a molding material behavior detection device that can improve the accuracy of detecting the behavior of the molding material in the cavity. [Means for solving the problem]

[0007] [1] The present invention provides A molding material behavior detection device that detects the behavior of a molding material in a mold cavity during molding, a waveform generating unit that generates a waveform of an input voltage at a predetermined frequency; an ultrasonic sensor that generates an ultrasonic guided wave; an output processing unit; Equipped with The ultrasonic sensor a propagating body including a first portion located outside the mold and a second portion located in a through-hole penetrating the mold, the propagating body being capable of propagating the guided wave extending in a longitudinal direction from the first portion to the second portion; a transmitting coil located in the first portion, the transmitting coil generating an input magnetic field in response to the input voltage to propagate the guided wave to the propagating body; a receiving coil located in the first portion, which generates an output voltage waveform in response to an output magnetic field generated based on the guided wave propagating through the propagating body; Including, the output processing unit processes the waveform of the output voltage to generate a detection result; the second portion includes a tip surface exposed to the cavity, The tip surface is located on the same plane as the inner surface of the mold, or is located more inward of the cavity than the inner surface. It may also be a molding material behavior detection device.

[0008] [2] The present invention is The ultrasonic sensor further includes a magnetostrictive body formed of a magnetostrictive material and positioned at the first portion of the propagating body, the magnetostrictive body receiving the input magnetic field from the transmitting coil to propagate the guided wave in the propagating body, and receiving the guided wave propagating in the propagating body to generate the output magnetic field toward the receiving coil. The molding material behavior detection device may be the one described in [1].

[0009] [3] The present invention provides The propagating body is formed of a metal material. The molding material behavior detection device may be the one described in [1] or [2].

[0010] [4] The present invention provides The transmitter coil and the receiver coil are located at a base end of the first portion opposite to the second portion. The molding material behavior detection device may be the molding material behavior detection device according to any one of [1] to [3].

[0011] [5] The present invention provides The ultrasonic sensor further includes a permanent magnet attached to the propagating body, the permanent magnet is located on the opposite side of the second portion from the transmitting coil and the receiving coil. The molding material behavior detection device may be the one described in any one of [1] to [4].

[0012] [6] The present invention provides the waveform generating unit generates the input voltage at a resonant frequency of the propagating body; the output processing unit generates a detection result including a determination result of whether or not the molding material is in contact with the second portion of the propagating body based on a change in the waveform of the output voltage. The molding material behavior detection device may be the molding material behavior detection device described in any one of [1] to [5].

[0013] [7] The present invention provides The output processing unit includes a Fourier transform unit that performs a Fourier transform on the waveform of the output voltage to create a frequency spectrum; an amplitude calculation unit that calculates an amplitude A at the resonance frequency from the frequency spectrum; an amplitude change calculation unit that calculates an amplitude change ΔA that is the difference between a reference amplitude A0, which is the amplitude at the resonance frequency obtained from the waveform of the output voltage when the molding material is not present in the cavity, and the amplitude A; a determination unit that determines whether the molding material is in contact with the second portion of the propagating body based on the amplitude change ΔA; and a result creation unit that creates the detection result including the determination result by the determination unit. [6] The molding material behavior detection device may be the one described above.

[0014] [8] The present invention provides The output processing unit calculates an envelope of the waveform of the output voltage by:

number

[0015] [9] The present invention provides The output processing unit includes a Fourier transform unit that performs a Fourier transform on the waveform of the output voltage to create a frequency spectrum; an amplitude calculation unit that calculates an amplitude A at the resonance frequency from the frequency spectrum; an amplitude change calculation unit that calculates an amplitude change ΔA that is the difference between a reference amplitude A0, which is the amplitude at the resonance frequency obtained from the waveform of the output voltage when the molding material is not present in the cavity, and the amplitude A; a heat transfer coefficient calculation unit that calculates a heat transfer coefficient between the molding material and the mold based on the amplitude change ΔA; and a result creation unit that creates the detection result including the heat transfer coefficient. [6] The molding material behavior detection device may be the one described above. [Effects of the Invention]

[0016] According to the present invention, it is possible to improve the accuracy of detecting the behavior of the molding material in the cavity. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a molding material behavior detection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of a waveform of an input voltage input to the transmission coil shown in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of a waveform of an output voltage output from the receiving coil shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of the output processing unit illustrated in FIG. [Figure 5] FIG. 5 is a schematic diagram showing an example of a frequency spectrum calculated in the output processing unit shown in FIG. [Figure 6] FIG. 6 is a schematic diagram showing an example of a time transition of the amplitude calculated in the output processing unit shown in FIG. [Figure 7] FIG. 7 is a diagram showing a modified example of the configuration of the output processing unit shown in FIG. [Figure 8]FIG. 8 is a schematic diagram showing an example of an envelope of the waveform of the output voltage output from the receiving coil in the output processing unit shown in FIG. [Figure 9] FIG. 9 is a schematic diagram showing an example of the time transition of the coefficients calculated in the output processing unit shown in FIG. [Figure 10] FIG. 10 is a schematic cross-sectional view showing another modified example of the molding material behavior detection device shown in FIG. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of an output processing unit in a molding material behavior detection device according to the second embodiment of the present invention. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a casting experiment device used in the examples of the present invention. [Figure 13] FIG. 13(a) is a schematic cross-sectional view showing the planar positions of thermocouples in the casting experimental apparatus shown in FIG. 9, and FIG. 13(b) is a schematic cross-sectional view showing the height positions of the thermocouples. [Figure 14] FIG. 14 is a diagram for explaining the relationship between the thermocouples shown in FIGS. 13(a) and 13(b). [Figure 15] FIG. 15(a) is a graph showing the temperature measurement results when the mold preheating temperature was 160°C, and FIG. 15(b) is a graph showing the relationship between the amplitude change ΔA and the heat transfer coefficient h at that time. [Figure 16] FIG. 16(a) is a graph showing the temperature measurement results when the mold preheating temperature was 270°C, and FIG. 16(b) is a graph showing the relationship between the amplitude change ΔA and the heat transfer coefficient h at that time. [Figure 17] FIG. 17 is a graph summarizing the relationship between the amplitude change ΔA and the heat transfer coefficient h shown in FIG. 15(b) and FIG. 16(b). [Figure 18] FIG. 18 is a diagram showing a compression test of the ultrasonic sensor shown in FIG. [Figure 19] FIG. 19 is a graph showing the relationship between the compression load and the amplitude change amount obtained in the compression test shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] (First embodiment) 1 to 10, a molding material behavior detection device 10 according to an embodiment of the present invention will be described. The molding material behavior detection device 10 is a device for detecting the behavior of a molding material M in a cavity 4 of a mold 1 during molding. The molding material behavior detection device 10 is intended to detect the behavior of the material in the process from when the molten molding material M is injected into the cavity 4 until it solidifies, and therefore the term "molding material" is used as a concept that encompasses both the molten material and the solidified material.

[0020] As shown in FIG. 1, the molding material behavior detection device 10 includes a waveform generating unit 11, an input amplifier 12, an ultrasonic sensor 13, an output amplifier 14, an output processing unit 15, and a display unit 16.

[0021] The waveform generating unit 11 is configured to generate an input voltage waveform at a predetermined frequency. The waveform generating unit 11 may generate an input voltage waveform at the resonant frequency of a propagating body 20, which will be described later. The waveform generating unit 11 may be configured to be able to adjust the frequency of the input voltage waveform to be generated. For example, if the length of a propagating body 20, which will be described later, is L, the frequency may be adjusted so that the wavelength is 2 / n times the length L (n is an integer equal to or greater than 1).

[0022] As shown in FIG. 2, the input voltage waveform generated by the waveform generating unit 11 may be a burst wave waveform including multiple guided waves. The guided wave is composed of multiple waves at resonant frequencies. t1 shown in FIG. 2 is the time interval between guided waves, and t2 is the time width for generating one guided wave. The waveform generating unit 11 generates an input voltage with such a burst wave waveform.

[0023] 1, input amplifier 12 is configured to amplify the waveform of the input voltage generated by waveform generating unit 11. If there is no need to amplify the waveform of the input voltage generated by waveform generating unit 11, input amplifier 12 may be omitted.

[0024] The ultrasonic sensor 13 is a magnetostrictive sensor that generates ultrasonic guided waves. The generated guided waves correspond to the waveform of the input voltage generated by the waveform generating unit 11 described above. In this embodiment, an example in which the ultrasonic sensor 13 is attached to a mold 1 (an example of a mold) will be described. The material of the molded product may be a metal material, a resin material, or a ceramic material. Molten metal obtained by melting a metal material is also called molten metal. The ultrasonic sensor 13 includes a propagating body 20, a transmitting coil 30, a magnetostrictive body 31, and a receiving coil 32.

[0025] The propagating body 20 includes a first portion 20a and a second portion 20b. The first portion 20a is a portion located outside the mold 1. The second portion 20b is a portion located in a through-hole 2 penetrating the mold 1 and inserted into the through-hole 2. The propagating body 20 extends in the longitudinal direction from the first portion 20a to the second portion 20b.

[0026] The first portion 20a includes a base end portion 21 of the propagating body 20. The base end portion 21 is an end portion of the first portion 20a located on the opposite side to the second portion 20b. The second portion 20b includes a tip end portion 22. The tip end portion 22 is an end portion of the second portion 20b located on the opposite side to the first portion 20a. The propagating body 20 extends in the longitudinal direction from the base end portion 21 to the tip end portion 22, with the base end portion 21 being located outside the mold 1 and the tip end portion 22 being located in the through-hole 2.

[0027] The propagating body 20 may be formed in a rod shape. The propagating body 20 may be formed in a solid rod shape (for example, a cylindrical shape) or a hollow rod shape (for example, a cylindrical shape). The propagating body 20 according to this embodiment is formed in a cylindrical shape. In this case, the outer circumferential surface of the propagating body 20 is formed in a circular shape when viewed in cross section. However, the outer circumferential surface of the propagating body 20 may be formed in an arbitrary polygonal shape such as a quadrangle when viewed in cross section.

[0028] The second portion 20b of the propagating body 20 includes a tip surface 23 of the propagating body 20 exposed to the cavity 4. The tip surface 23 is located at the very tip of the tip portion 22. When the propagating body 20 is formed in a cylindrical shape as in this embodiment, a member constituting the tip surface 23 may be joined to the tip of a cylindrical rod by welding or the like.

[0029] The tip surface 23 may be located on the same plane as the inner surface 3 of the mold 1. On the same plane means that the inner surface 3 of the mold 1 and the tip surface 23 of the propagating body 20 form a continuous surface. However, without being bound by the strict meaning, it is permissible for a minute step to be formed between the inner surface 3 of the mold 1 and the tip surface 23 of the propagating body 20, as long as it does not substantially affect the outer shape of the molded product.

[0030] The propagating body 20 is configured to be able to propagate ultrasonic guided waves. The propagating body 20 may be formed of a metal material. The propagating body 20 may be formed of a magnetic material. Examples of materials for the propagating body 20 include steel materials. Furthermore, the propagating body 20 may be made of a material that does not react with the molding material during molding. This prevents the molding material from adhering to the propagating body 20 and prevents the propagating body 20 from melting.

[0031] The transmitting coil 30 generates an input magnetic field based on the waveform of the input voltage generated by the waveform generating unit 11, thereby propagating a guided wave in the propagating body 20. The waveform of the input magnetic field generated by the transmitting coil 30 corresponds to the waveform of the input voltage amplified by the input amplifier 12 described above. The transmitting coil 30 is located on the first portion 20a of the propagating body 20. The transmitting coil 30 is wound around the outer peripheral surface of a magnetostrictive body 31, which will be described later. The transmitting coil 30 and the magnetostrictive body 31 may be located at the base end 21 of the propagating body 20.

[0032] The magnetostrictive body 31 is located in the first portion 20a of the propagating body 20. The magnetostrictive body 31 may be located in the base end portion 21 of the propagating body 20. The magnetostrictive body 31 is joined to the propagating body 20, and ultrasonic vibrations generated in the magnetostrictive body 31 are propagated to the propagating body 20. The magnetostrictive body 31 may be formed in a cylindrical shape on the outer circumferential surface of the propagating body 20.

[0033] The magnetostrictive body 31 is made of a magnetostrictive material. The magnetostrictive body 31 may be made of a material that can exhibit a magnetostrictive effect. An example of such a material is nickel. The magnetostrictive body 31 may be formed by nickel plating the base end 21 of the transmitting body 20.

[0034] The magnetostrictive body 31 receives the input magnetic field generated by the transmitting coil 30 and propagates an ultrasonic guided wave to the propagation body 20. The magnetostrictive body 31 receives the input magnetic field and generates an ultrasonic guided wave due to the magnetostrictive effect. The generated guided wave propagates to the propagation body 20. The waveform of the ultrasonic wave generated by the magnetostrictive body 31 corresponds to the waveform of the input voltage, and may be a waveform of a burst wave including multiple guided waves.

[0035] The magnetostrictive body 31 generates an output magnetic field by receiving the guided wave propagating inside the propagating body 20 due to the inverse magnetostrictive effect. The magnetostrictive body 31 generates an output magnetic field by receiving the guided wave that has reached the portion of the propagating body 20 facing the receiving coil 32 (the inner portion of the receiving coil 32). The waveform of the guided wave propagating inside the propagating body 20 can attenuate depending on changes in ambient conditions, such as whether or not the molding material M is in contact with the tip end surface 23. The waveform of the output magnetic field generated by the magnetostrictive body 31 corresponds to the waveform of the ultrasonic wave propagating inside the propagating body 20.

[0036] The receiving coil 32 generates an output voltage waveform according to the output magnetic field generated based on the guided wave propagating through the propagating body 20. In this embodiment, the output magnetic field is generated by the magnetostrictive body 31. The waveform of the output voltage corresponds to the waveform of the output magnetic field and may be a waveform of a burst wave including multiple guided waves. The waveform of the output voltage may differ from the waveform of the input voltage shown in FIG. 2 depending on the surrounding conditions of the tip end surface 23 of the propagating body 20. In the example shown in FIG. 3, each guided wave of the output voltage is attenuated relative to each guided wave of the input voltage, but the third guided wave shown in FIG. 3 is attenuated relatively greatly. This means that the tip end surface 23 has come into contact with the molding material M that has arrived.

[0037] 1, the receiving coil 32 is located at the first portion 20a of the propagating body 20. The receiving coil 32 is wound around the outer peripheral surface of the magnetostrictive body 31. The receiving coil 32 and the magnetostrictive body 31 may be located at the base end portion 21 of the propagating body 20. The receiving coil 32 may be located closer to the second portion 20b of the propagating body 20 than the transmitting coil 30. However, the receiving coil 32 may be located on the opposite side of the transmitting coil 30 from the second portion 20b.

[0038] The ultrasonic sensor 13 according to this embodiment may further include a permanent magnet 33 attached to the propagating body 20. The permanent magnet 33 may be located on the opposite side of the second portion 20b from the transmitting coil 30 and the receiving coil 32. In this case, a bias magnetic field can be added by the permanent magnet 33 to the input magnetic field generated by the transmitting coil 30. This allows the magnetostrictive body 31 to vibrate more strongly, thereby improving the transmission efficiency of the guided wave. Similarly, by adding a bias magnetic field to the receiving coil 32 using the permanent magnet 33, the output magnetic field generated by the magnetostrictive body 31 in response to the arrival of the guided wave can be further strengthened, thereby improving the reception efficiency of the guided wave. However, the ultrasonic sensor 13 does not necessarily include such a permanent magnet 33.

[0039] The output amplifier 14 is configured to amplify the waveform of the output voltage generated by the above-described receiving coil 32. If there is no need to amplify the waveform of the output voltage generated by the receiving coil 32, the output amplifier 14 may be omitted.

[0040] The output processing unit 15 processes the waveform of the output voltage generated by the receiving coil 32 described above to create a detection result. The output processing unit 15 may create a detection result by receiving the waveform of the output voltage amplified by the output amplifier 14 described above. Specific examples of the detection result are not particularly limited. For example, the detection result may include the waveform of the output voltage, but the following description will be given of an example in which a detection result is created that includes a determination result of whether or not the molding material M is in contact with the tip surface 23 of the propagating body 20.

[0041] The output processing unit 15 according to this embodiment is configured to determine whether the molding material M is in contact with the tip surface 23 of the propagating body 20 based on a change in the waveform of the output voltage, and to create a detection result including the determination result. More specifically, the output processing unit 15 makes the determination based on a change in the amplitude of the output voltage at the resonance frequency.

[0042] As shown in FIG. 4, the output processing unit 15 may include an acquisition unit 40, a Fourier transform unit 41, an amplitude calculation unit 42, an amplitude change amount calculation unit 43, a determination unit 44, a result creation unit 45, and a memory unit 46.

[0043] The acquiring unit 40 acquires the waveform of the amplified output voltage from the output amplifier 14. The acquiring unit 40 may be connected to the output amplifier 14 by wire or wirelessly. When the output amplifier 14 is not used, the acquiring unit 40 may be connected to the receiving coil 32 by wire or wirelessly.

[0044] The Fourier transform unit 41 performs a Fourier transform on the waveform of the output voltage acquired by the acquisition unit 40. More specifically, the Fourier transform unit 41 performs a Fourier transform on the waveform of the output voltage generated by the receiving coil 32 to create a frequency spectrum as shown in Fig. 5. The frequency spectrum indicates the frequency components of the waveform of the output voltage. A frequency spectrum is created for each guide.

[0045] The amplitude calculation unit 42 calculates the amplitude A at the resonant frequency from the frequency spectrum created by the Fourier transform unit 41. In the frequency spectrum shown in FIG. 5, the amplitude at the resonant frequency f0 is shown as amplitude A1 as an example. The amplitude calculation unit 42 calculates the amplitude A for each guided wave. As a result, the time transition of the amplitude A is obtained, an example of which is shown in FIG. 6.

[0046] The reference amplitude A0 shown in Fig. 6 is the amplitude at the resonant frequency obtained from the waveform of the output voltage when the molding material M is not present in the cavity 4 of the mold 1. More specifically, similar to the process for calculating the amplitude A described above, the waveform of the output voltage when the molding material M is not present in the cavity 4 is Fourier transformed, and the amplitude at the resonant frequency is calculated as the reference amplitude A0. The reference amplitude A0 may be obtained in advance when the molding material M is not present in the cavity 4 and stored in the storage unit 46 described later. The amplitude A1 shown in Fig. 6 represents the amplitude when the molding material M is in contact with the tip end surface 23.

[0047] The amplitude change amount calculation unit 43 calculates the amplitude change amount ΔA. The amplitude change amount ΔA is the difference between the reference amplitude A0 described above and the amplitude A calculated by the amplitude calculation unit 42, and is expressed as ΔA=A0−A. The amplitude change amount calculation unit 43 calculates the amplitude change amount ΔA for each guided wave. As a result, the time transition of the amplitude change amount ΔA is obtained, examples of which are shown in Fig. 15(b) and Fig. 16(b) described later.

[0048] The determination unit 44 determines whether the molding material M is in contact with the tip surface 23 of the propagating body 20. More specifically, the determination unit 44 determines whether the molding material M is in contact with the tip surface 23 based on the amplitude change amount ΔA calculated by the amplitude change amount calculation unit 43. The determination unit 44 may make the determination based on whether the amplitude change amount ΔA is greater than an amplitude change amount threshold. For example, if the amplitude change amount ΔA is greater than the amplitude change amount threshold, it is determined that the molding material M is in contact with the tip surface 23. On the other hand, if the amplitude change amount ΔA is equal to or less than the amplitude change amount threshold, it is determined that the molding material M is not in contact with the tip surface 23. The determination unit 44 makes the determination by comparing the amplitude change amount ΔA with the amplitude change amount threshold for each guided wave. The amplitude change amount threshold can be any value as long as it can be set as a threshold for determining whether the molding material M is in contact with the tip surface 23 of the propagating body 20.

[0049] The result creation unit 45 creates a detection result by processing the waveform of the output voltage from the receiving coil 32. The detection result created by the result creation unit 45 in this embodiment includes the determination result of the determination unit 44. When a determination result is obtained for each guided wave, each determination result is associated with the time from the start of injection of the molding material M. This makes it possible to know from the detection result the time from the start of injection of the molding material M until the molding material M reaches and contacts the tip surface 23 of the propagating body 20, as well as the time when the molding material M solidifies and separates from the tip surface 23. The detection result created by the result creation unit 45 is displayed on the display unit 16, which will be described later.

[0050] The storage unit 46 is configured to store any information and may be configured as, for example, a memory or a storage. For example, the storage unit 46 may store the above-mentioned amplitude A, reference amplitude A0, amplitude change amount ΔA, amplitude change amount threshold, and determination result. The storage unit 46 may also store a computer program for realizing the function of the output processing unit 15.

[0051] The display unit 16 displays the detection results created by the output processing unit 15. The display unit 16 may be configured with a display. The display unit 16 according to this embodiment displays the detection results including the determination results by the determination unit 44 described above. The display unit 16 may also display the amplitude change amount ΔA calculated by the amplitude change amount calculation unit 43 and the waveform of the output voltage.

[0052] Next, a molding material behavior detection method using the molding material behavior detection device 10 according to this embodiment configured as described above will be described.

[0053] First, an input voltage waveform is generated by the waveform generating unit 11 shown in Fig. 1. The input voltage waveform may be a waveform whose frequency is the resonant frequency of the propagating body 20 of the ultrasonic sensor 13. The input voltage waveform may be a waveform of a burst wave including multiple guided waves. The input voltage waveform is amplified by the input amplifier 12 and input to the transmitting coil 30 of the ultrasonic sensor 13.

[0054] In the transmitting coil 30, an input magnetic field is generated in accordance with the waveform of the input voltage, and is applied to the magnetostrictive body 31. The magnetostrictive body 31 vibrates ultrasonically due to the magnetostrictive effect. As a result, an ultrasonic guided wave is generated in accordance with the waveform of the input voltage, and propagates to the propagating body 20.

[0055] The guided wave propagates within the propagating body 20. The magnetostrictive body 31 receives the guided wave that has propagated within the propagating body 20 and reached the portion facing the receiving coil 32 due to the inverse magnetostrictive effect, and generates an output magnetic field. The generated magnetic field is applied to the receiving coil 32.

[0056] In the receiving coil 32, an output voltage waveform is generated in accordance with the output magnetic field generated in the magnetostrictive body 31. The output voltage waveform is processed in the output processing unit 15.

[0057] More specifically, the acquisition unit 40 of the output processing unit 15 acquires the waveform of the output voltage generated in the receiving coil 32. The Fourier transform unit 41 performs Fourier transform on the waveform of the output voltage to create a frequency spectrum for each guided wave. The amplitude calculation unit 42 calculates the amplitude A at the resonance frequency from the frequency spectrum, and the amplitude change amount ΔA, which is the difference between the reference amplitude A0 and the amplitude A, is calculated by the amplitude change amount calculation unit 43. Based on the amplitude change amount ΔA, the determination unit 44 determines whether or not the molding material M is in contact with the tip surface 23 of the propagating body 20. Thereafter, the result creation unit 45 creates a detection result including the determination result by the determination unit 44 and displays it on the display unit 16.

[0058] From the start of injection of the molding material M into the cavity 4 until the molding material M reaches and contacts the tip surface 23, the resonant state of the guided wave is maintained, and the amplitude of the output voltage waveform at the resonant frequency does not change substantially. As a result, the amplitude A calculated by the amplitude calculation unit 42 becomes the same as or close to the reference amplitude A0. Therefore, the amplitude change amount ΔA becomes equal to or less than the amplitude change amount threshold, and the determination unit 44 determines that the molding material M is not in contact with the tip surface 23 of the propagating body 20.

[0059] When the molding material M reaches and contacts the tip surface 23, the ultrasonic waves propagating to the tip surface 23 leak into the molding material M, and the guided wave deviates from the resonant state. As a result, the guided wave propagating within the propagating body 20 is attenuated, and the amplitude A calculated by the amplitude calculation unit 42 becomes smaller than the reference amplitude A0. Therefore, when the amplitude change amount ΔA becomes larger than the amplitude change amount threshold, the determination unit 44 determines that the molding material M is in contact with the tip surface 23 of the propagating body 20.

[0060] When the molding material M in contact with the tip surface 23 solidifies, the molding material M may shrink and be peeled off and separated from the tip surface 23. In this case, the resonant frequency of the propagating body 20 substantially returns to the state before the molding material M contacted the tip surface 23, and the amplitude A becomes the same as or close to the reference amplitude A0. Therefore, the amplitude change amount ΔA becomes equal to or less than the amplitude change amount threshold, and the determining unit 44 determines that the molding material M is not in contact with the tip surface 23 of the propagating body 20.

[0061] In this way, a judgment result is obtained for each guided wave. The judgment result for each guided wave is associated with the time from the start of injection of the molding material M, constitutes the detection result of the output processing unit 15, and is displayed on the display unit 16.

[0062] The operator can check the detection results displayed on the display unit 16 to know the time when the molding material M reaches and contacts the tip surface 23 of the propagating body 20, as well as the time when the molding material M solidifies and separates from the tip surface 23. By comparing these times with the calculation results of the molding process simulation, it can be confirmed whether the simulation is consistent with the actual molding process. If the calculation results do not match the actual molding process, the accuracy of the simulation can be improved by adjusting the simulation parameters, etc.

[0063] As described above, according to this embodiment, the tip surface 23 of the propagating body 20 of the ultrasonic sensor 13 is located on the same plane as the inner surface 3 of the mold 1. As a result, when the molding material M reaches the position of the tip surface 23, the molding material M can come into direct contact with the tip surface 23. This makes it possible to change the resonant frequency of the propagating body 20, and to accurately detect the arrival time of the molding material M. As a result, the accuracy of detecting the behavior of the molding material M in the cavity 4 can be improved.

[0064] For example, when an ultrasonic vibrator is attached to the outer surface of the mold 1 and ultrasonic waves are irradiated toward the cavity 4, the ultrasonic waves are diffused within the mold 1, making it difficult to improve detection accuracy. Another reason for the difficulty in improving detection accuracy is that the molding material M does not come into direct contact with the ultrasonic vibrator. However, according to this embodiment, the tip surface 23 of the propagating body 20 is located on the same plane as the inner surface 3 of the mold 1, so that when the molding material M arrives, it can come into direct contact with the tip surface 23, thereby improving detection accuracy.

[0065] Furthermore, when an ultrasonic vibrator is configured with a piezoelectric element, the piezoelectric element has a problem with high-temperature resistance. However, according to the present embodiment, the ultrasonic sensor 13 does not use a piezoelectric element, so the high-temperature resistance of the ultrasonic sensor 13 can be improved and it can withstand the high temperature of the molten molding material M. Furthermore, in the ultrasonic sensor 13 according to the present embodiment, the transmitting coil 30 and the receiving coil 32 are located in the first portion 20a of the propagating body 20 located outside the mold 1. Therefore, the transmitting coil 30 and the receiving coil 32 can be kept away from the high-temperature molding material M, which also improves the high-temperature resistance of the ultrasonic sensor 13.

[0066] The ultrasonic sensor 13 according to this embodiment can also be applied to sand molds. That is, it is difficult to attach a piezoelectric element to the outer surface of a sand mold. In contrast, according to this embodiment, the transmitting body 20 of the ultrasonic sensor 13 can be placed at a desired position on the wooden mold (core) when the sand mold is made. Therefore, the transmitting body 20 can be placed so as to penetrate the made sand mold, and the molding material behavior detection device 10 according to this embodiment can also be easily applied to sand molds.

[0067] Furthermore, according to this embodiment, no piezoelectric element is used in the ultrasonic sensor 13. Generally, piezoelectric elements that are resistant to high temperatures are expensive, but because the ultrasonic sensor 13 according to this embodiment is a magnetostrictive type, the cost of the ultrasonic sensor 13 can be reduced.

[0068] According to the present embodiment, the ultrasonic sensor 13 includes a magnetostrictive body 31 located in the first portion 20a of the propagating body 20. The magnetostrictive body 31 receives an input magnetic field generated by the transmitting coil 30 to propagate a guided wave in the propagating body 20, and also receives a guided wave that propagates through the propagating body 20 and reaches a portion facing the receiving coil 32 to generate an output magnetic field. This allows the magnetostrictive effect to be utilized to effectively generate a guided wave in the propagating body 20, and the inverse magnetostrictive effect to effectively generate an output magnetic field. The magnetostrictive body 31 can be formed by plating the propagating body 20, which further reduces the cost of the ultrasonic sensor 13. Forming the magnetostrictive body 31 by plating can strengthen the bond between the propagating body 20 and the magnetostrictive body 31, thereby improving the propagation efficiency of the guided wave between the propagating body 20 and the magnetostrictive body 31. This improves the detection accuracy of the behavior of the molding material M.

[0069] Furthermore, according to this embodiment, the propagating body 20 is made of a metal material, which can improve the high temperature resistance of the ultrasonic sensor 13. For example, compared to a resin material, the use of a metal material can improve high temperature resistance and toughness.

[0070] Furthermore, according to this embodiment, the transmitting coil 30 and the receiving coil 32 are located at the base end of the first portion 20a of the propagating body 20, which is located on the opposite side to the second portion 20b. This allows the transmitting coil 30 and the receiving coil 32 to be kept away from the high-temperature molding material M and also from the mold 1. This improves the high-temperature resistance of the ultrasonic sensor 13.

[0071] Furthermore, according to this embodiment, when the propagating body 20 of the ultrasonic sensor 13 is provided with a permanent magnet 33 located on the opposite side of the transmitting coil 30 from the second portion 20b, the input magnetic field generated by the transmitting coil 30 can be strengthened, and the output magnetic field applied to the receiving coil 32 can be strengthened. This increases the S / N ratio and reduces the influence of noise. This further improves the detection accuracy.

[0072] Furthermore, according to this embodiment, the waveform generating unit 11 generates an input voltage at the resonant frequency of the propagating body 20. The output processing unit 15 generates a detection result including a determination result as to whether or not the molding material M is in contact with the tip surface 23 of the propagating body 20 based on a change in the waveform of the output voltage. This makes it possible to accurately detect, from the waveform of the output voltage, that the molding material M has reached the tip surface 23 of the propagating body 20. This further improves the detection accuracy of the behavior of the molding material M in the cavity 4.

[0073] Furthermore, according to this embodiment, the output processing unit 15 performs a Fourier transform on the waveform of the output voltage to calculate the amplitude A at the resonance frequency, and calculates an amplitude change amount ΔA, which is the difference between the reference amplitude A0 and the amplitude A. A detection result including a determination result as to whether or not the molding material M is in contact with the tip surface 23 of the propagating body 20 is output based on the amplitude change amount ΔA. As a result, by utilizing the fact that the amplitude of the guided wave is maximum at the resonance frequency of the propagating body 20, it is possible to accurately detect from the waveform of the output voltage that the molding material M has reached the tip surface 23 of the propagating body 20. This makes it possible to further improve the accuracy of detecting the behavior of the molding material M in the cavity 4.

[0074] In the above-described embodiment, the output processing unit 15 performs the determination based on the change in the amplitude of the output voltage at the resonant frequency. However, the configuration of the output processing unit 15 is arbitrary. For example, the output processing unit 15 may perform the determination based on the change in the waveform of the output voltage.

[0075] 7, the output processing unit 15 may include an acquisition unit 40, a coefficient calculation unit 50, a coefficient change amount calculation unit 51, a determination unit 52, a result creation unit 53, and a storage unit 46. The acquisition unit 40 and the storage unit 46 may be configured similarly to the acquisition unit 40 shown in FIG.

[0076] The coefficient calculation unit 50 calculates a coefficient a when the envelope of the waveform of the output voltage acquired by the acquisition unit 40 is expressed by the following equation (1), where t is time and b is a constant.

number

[0077] 9 is a coefficient obtained from the waveform of the output voltage when the molding material M is not present in the cavity 4. More specifically, it is calculated in the same manner as the process for calculating the coefficient a described above. The reference coefficient a0 may be obtained in advance when the molding material M is not present in the cavity 4 and stored in the storage unit 46.

[0078] When the molding material M reaches and contacts the tip surface 23 of the propagating body 20, the resonant frequency of the propagating body 20 changes. While the molding material M is in contact with the tip surface 23, the attenuation of the guided wave is strong, and the coefficient a calculated by the coefficient calculation unit 50 becomes larger than the reference coefficient a0. The coefficient a in this case is shown as coefficient a1 in FIG. 9. However, when the contacting molding material M solidifies and shrinks, the solidified material may peel off and separate from the tip surface 23. In this case, as shown in FIG. 9, the resonant frequency of the propagating body 20 substantially returns to its original state, and the coefficient a returns to the reference coefficient a0 or becomes a value close to the reference coefficient a0.

[0079] The coefficient change amount calculation unit 51 calculates the coefficient change amount Δa. The coefficient change amount Δa is the difference between the reference coefficient a0 and the coefficient a calculated by the coefficient calculation unit 50. The coefficient change amount calculation unit 51 calculates the coefficient change amount Δa for each guide wave. As a result, the time transition of the coefficient change amount Δa is obtained.

[0080] The determination unit 52 determines whether the molding material M is in contact with the tip surface 23 of the propagating body 20. More specifically, the determination unit 52 determines whether the molding material M is in contact with the tip surface 23 based on the coefficient change amount Δa calculated by the coefficient change amount calculation unit 51. The determination unit 52 may make the determination depending on whether the coefficient change amount Δa is greater than a coefficient change amount threshold. For example, if the coefficient change amount Δa is greater than the coefficient change amount threshold, the determination unit 52 determines that the molding material M is in contact with the tip surface 23. On the other hand, if the coefficient change amount Δa is equal to or less than the coefficient change amount threshold, the determination unit 52 determines that the molding material M is not in contact with the tip surface 23. The determination unit 52 makes the determination by comparing the coefficient change amount Δa with the coefficient change amount threshold for each guided wave. The coefficient change amount threshold can be any value as long as it can be set as a threshold for determining whether the molding material M is in contact with the tip surface 23.

[0081] The result creation unit 53 creates a detection result by processing the waveform of the output voltage from the receiving coil 32. The detection result created by the result creation unit 53 in this embodiment includes the determination result of the determination unit 52. When a determination result is obtained for each guided wave, each determination result is associated with the time from the start of injection of the molding material M. This makes it possible to know from the detection result the time from the start of injection of the molding material M until the molding material M reaches and contacts the tip surface 23 of the propagating body 20, as well as the time when the molding material M solidifies and separates from the tip surface 23. The detection result created by the result creation unit 53 is displayed on the display unit 16.

[0082] 7 to 9, the output processing unit 15 calculates the coefficient a when the envelope of the waveform of the output voltage is expressed by the above formula (1), and calculates the coefficient change amount Δa, which is the difference between the reference coefficient a0 and the coefficient a. Based on the coefficient change amount Δa, a detection result including a determination result as to whether or not the molding material M is in contact with the tip surface 23 of the propagating body 20 is output. This makes it possible to accurately detect, from the waveform of the output voltage, that the molding material M has reached the tip surface 23 of the propagating body 20. This further improves the accuracy of detecting the behavior of the molding material M in the cavity 4.

[0083] In the above-described embodiment, the tip surface 23 of the propagating body 20 is located on the same plane as the inner surface 3 of the mold 1. However, the embodiment is not limited to this. For example, as shown in FIG. 10 , the tip surface 23 of the propagating body 20 may be located closer to the cavity 4 than the inner surface 3 of the mold 1. The tip portion 22 of the propagating body 20 may protrude further inward than the inner surface 3. Even in this case, the molding material M that has reached the tip surface 23 of the propagating body 20 comes into contact with the tip surface 23, thereby changing the resonant frequency of the propagating body 20. This attenuates the guided wave propagating within the propagating body 20, making it possible to determine whether the molding material M is in contact with the tip portion 22 of the propagating body 20. Furthermore, even when the molding material M is in contact with the outer peripheral surface 24 of the tip portion 22 that protrudes from the inner surface 3, the same determination can be made.

[0084] In the above-described embodiment, the magnetostrictive body 31 is formed by nickel plating the base end portion 21 of the propagating body 20. However, as long as the magnetostrictive body 31 is joined to the base end portion 21, it may be bonded to the base end portion 21 using an adhesive or may be brazed.

[0085] In the above-described embodiment, the magnetostrictive body 31 is formed on the base end portion 21 of the propagating body 20. However, if the propagating body 20 is made of a magnetic material, the magnetostrictive body 31 may not be formed.

[0086] In the above-described embodiment, the propagating body 20 is made of a metal material. However, the propagating body 20 may be made of a resin material or a ceramic material. In this case, the magnetostrictive body 31 may be bonded to the base end portion 21 of the propagating body 20 with an adhesive or may be brazed.

[0087] In the above-described embodiment, the example has been described in which the transmitting coil 30, the magnetostrictive body 31, and the receiving coil 32 are located at the base end 21 of the propagating body 20. However, the transmitting coil 30, the magnetostrictive body 31, and the receiving coil 32 are not limited to being located at the base end 21 as long as they are located at the first portion 20a located outside the mold 1.

[0088] (Second embodiment) Next, a molding material behavior detection device according to a second embodiment will be described with reference to FIG.

[0089] The second embodiment shown in Fig. 11 differs mainly in that a detection result including a heat transfer coefficient calculated based on the amplitude change amount ΔA is created, and other configurations are substantially the same as those of the first embodiment shown in Fig. 1 to Fig. 10. In Fig. 11, the same parts as those of the first embodiment shown in Fig. 1 to Fig. 10 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0090] 11, output processing unit 15 according to this embodiment calculates an amplitude change amount based on the amplitude of the output voltage at the resonant frequency, and calculates a heat transfer coefficient based on the amplitude change amount. In this case, output processing unit 15 may include an acquisition unit 40, a Fourier transform unit 41, an amplitude calculation unit 42, an amplitude change amount calculation unit 43, a heat transfer coefficient calculation unit 60, a result creation unit 61, and a storage unit 46. The acquisition unit 40, the Fourier transform unit 41, the amplitude calculation unit 42, the amplitude change amount calculation unit 43, and the storage unit 46 may be configured similarly to the acquisition unit 40, the Fourier transform unit 41, the amplitude calculation unit 42, the amplitude change amount calculation unit 43, and the storage unit 46 shown in FIG.

[0091] The heat transfer coefficient calculation unit 60 calculates the heat transfer coefficient h based on the amplitude change amount ΔA calculated by the amplitude change amount calculation unit 43. For example, the heat transfer coefficient h may be calculated using the following formula (2). The details of formula (2) will be described later, but formula (2) is an example for calculating the heat transfer coefficient h. The formula is set arbitrarily depending on the shape and type of the mold 1.

number

[0092] The heat transfer coefficient calculation unit 60 calculates the heat transfer coefficient h for each guide wave. As a result, the time transition of the heat transfer coefficient h is obtained, examples of which are shown in Fig. 15(b) and Fig. 16(b) described later.

[0093] The result creation unit 61 creates a detection result including the heat transfer coefficient h calculated by the heat transfer coefficient calculation unit 60. The detection result created by the result creation unit 61 according to this embodiment includes the heat transfer coefficient h. When the heat transfer coefficient is obtained for each guided wave, each heat transfer coefficient is associated with the time since the start of injection of the molding material M. The detection result created by the result creation unit 61 may be a graph showing the relationship between the heat transfer coefficient h and time, as shown in FIG. 15(b) and FIG. 16(b). The detection result created by the result creation unit 61 is displayed on the display unit 16.

[0094] As described above, according to this embodiment, the output processing unit 15 performs a Fourier transform on the waveform of the output voltage to calculate the amplitude A at the resonance frequency, and calculates the amplitude change amount ΔA, which is the difference between the reference amplitude A0 and the amplitude A. Based on the amplitude change amount ΔA, a detection result including the heat transfer coefficient h between the molding material M and the mold 1 is output. This makes it possible to obtain the heat transfer coefficient h between the molding material M and the mold 1. The obtained heat transfer coefficient h can be used as a parameter for simulating the molding process. This improves the accuracy of the simulation. [Example]

[0095] A casting experiment was conducted using a molding experimental device simulating the molding material behavior detection device 10 according to the embodiment described above. This casting experiment will be described below with reference to Figs. 12 to 19. In the experiment, molten aluminum alloy as molding material M was poured into cavity 73 of experimental mold 70 to be molded. During molding, the waveform of the output voltage from ultrasonic sensor 13 was acquired, and the temperatures shown below were measured. As a result, the relationship between the amplitude change ΔA and the heat transfer coefficient h shown in the above formula (1) was obtained.

[0096] First, the molding experiment equipment will be described.

[0097] As shown in FIG. 12 , a casting mold 70 was fabricated by combining a steel plate (SKD61: hot work tool steel) 71 and an insulating plate 72. The insulating plate 72 was made of Lumiboard (registered trademark) manufactured by Nichias Corporation, which is primarily made of calcium silicate. The steel plate 71 was 15 mm thick, and the insulating plate 72 was 15 mm thick. The cavity 73 of the mold 70 was formed in a rectangular column shape with a thickness of 15 mm, a depth of 20 mm, and a height of 100 mm. A through hole 74 was formed in the steel plate 71, and the transmitting body 20 of the ultrasonic sensor 13 was inserted into the through hole 74, with the tip surface 23 of the transmitting body 20 being flush with the inner surface 75 of the steel plate 71.

[0098] The ultrasonic sensor 13 will now be described in detail. A φ6 mm solid round bar made of steel (general structural rolled steel) was used for the propagating body 20. The outer circumferential surface of the base end portion 21 was plated with Ni to a thickness of approximately 50 μm to form the magnetostrictive body 31. A transmitting coil 30 and a receiving coil 32 were wound around the outer circumferential surface of the magnetostrictive body 31.

[0099] As shown in Figures 13(a) and 13(b), a thermocouple 81 was installed in the mold 70 to measure temperature changes inside the molten metal during casting. Thermocouples 82 and 83 were attached to the transmitter 20 of the ultrasonic sensor 13 to measure temperature changes in the transmitter 20. Thermocouples 81-83 were 0.5 mm diameter sheathed thermocouples with the wire only exposed at the tip. As shown in Figure 13(b), the tip of thermocouple 81 was installed 1-2 mm inside the cavity 73 from the inner surface 75 of the steel plate 71. After the molten metal was poured, this thermocouple 81 was cast into the molten metal, allowing temperature changes inside the molten metal to be measured. To determine the exact measurement position, the casting (molded product) was cut after casting to confirm the tip position of thermocouple 81, and this was reflected in the calculation of the heat transfer coefficient described below. A thermocouple 82 was welded to the tip 22 of the propagating body 20 at a position 2 mm from the tip surface 23, and a thermocouple 83 was welded to the tip 22 at a position 6 mm from the tip surface 23. As shown in Figure 13(a), the measurement position of the thermocouple 81 inside the molten metal and the measurement positions of the two thermocouples 82 and 83 attached to the tip 22 of the propagating body 20 were set so as to be positioned on a straight line.

[0100] Next, an experimental method using the above-mentioned molding experimental apparatus will be described.

[0101] After preheating the steel plate 71 and the heat insulating plate 72 to a predetermined temperature (two levels: 160°C and 270°C), molten metal (ADC12: aluminum alloy) at 750°C was poured into the cavity 73 from the top of the mold 70 and allowed to solidify. The preheat temperature of the mold 70 was changed because it was thought that the time required for the molten metal to solidify would change, allowing differences in the contact state to be confirmed. During casting, the contact between the molten metal and the tip surface 23 of the propagating body 20 was checked with an ultrasonic sensor 13, and temperature changes inside the molten metal and the propagating body 20 were checked with a thermocouple 81 installed in the cavity 73 and thermocouples 82 and 83 attached to the propagating body 20.

[0102] During casting, a burst signal containing multiple high-frequency (42.3 kHz) guided waves was input to the transmitting coil 30 at 0.1-second intervals (corresponding to t1 in Figure 2), causing the magnetostrictive body 31 to vibrate due to its magnetostrictive effect, generating ultrasonic guided waves. The frequency of the guided waves was adjusted to bring the guided waves into a resonant state. The output voltage generated by the receiving coil 32 was then acquired, and the amplitude change ΔA described above was calculated as a parameter representing the change in the amplitude of the output voltage waveform. Figure 15(b) shows the results when the preheating temperature was 160°C, and Figure 16(b) shows the results when the preheating temperature was 270°C.

[0103] Meanwhile, the heat transfer coefficient h between the molten metal and the steel plate 71 of the mold 70 was determined from the temperature measurement results of a thermocouple 81 installed inside the molten metal and thermocouples 82 and 83 attached to the tip 22 of the propagator 20.

[0104] More specifically, as shown in FIG. 14, the temperature measurement positions by thermocouples 81, 82, and 83 were designated as X1, X2, and X3, respectively, and the respective temperatures were designated as T1, T2, and T3.

[0105] Mold 70 combines steel plate 71 and heat insulating plate 72, and it is considered that the heat of the molten metal is transferred to the outside mainly only through steel plate 71. For this reason, it is assumed that the heat transfer from the molten metal to the steel plate 71 side including the propagator 20 is one-dimensional unsteady heat conduction. In this case, from temperatures T1, T2, and T3 measured at a certain time n, temperature T2 at time n+1 Δt seconds later can be calculated by the following equation (3), which is a discrete expression of the one-dimensional unsteady heat conduction equation.

number

[0106] Here, the superscripts n and n+1 of the temperature T represent time. m and λ m are the heat capacity and thermal conductivity of the propagating body 20, and x1 and x2 are the distance between the position X1 and the position X2 and the distance between the position X2 and the position X3, respectively, as shown in FIG. cm is the thermal conductivity between X1 and X2, and the thermal conductivity of the molten metal λc and the thermal conductivity λ of the propagating body 20 m and the heat transfer coefficient h of the interface where the molten metal and the propagating body 20 come into contact, and the distance x3 between the interface and X1, which is expressed by the following formula (4).

number

[0107] Temperature T1 at time n n , T2 n and T3 n Based on the temperature T2 at the next time n+1 n+1’ was calculated from the above equations (3) and (4). In this case, the calculation was repeated by changing the heat transfer coefficient h, and the temperature T2 obtained by the calculation n+1’ is the measured temperature T (2,mes) n+1 The heat transfer coefficient h at time n+1 was calculated as the value closest to h. The results when the preheating temperature was 160°C are shown in Figure 15(b), and the results when the preheating temperature was 270°C are shown in Figure 16(b).

[0108] Figure 15(a) shows the changes over time in temperatures T1, T2, and T3 of thermocouples 81, 82, and 83 when the preheating temperature is 160°C, and Figure 16(a) shows the changes over time in temperatures T1, T2, and T3 of thermocouples 81, 82, and 83 when the preheating temperature is 270°C. After the molten metal is poured, the molten metal comes into contact with thermocouple 81, and temperature T1 rises sharply. Temperatures T2 and T3 of thermocouples 82 and 83 also rise after pouring, but temperature T2, which is closer to the molten metal, is higher.

[0109] Figure 15(b) shows the time change in amplitude change ΔA of the output voltage waveform generated in the receiving coil 32 of the ultrasonic sensor 13 and the heat transfer coefficient h when the preheating temperature was 160°C. The horizontal axis, time, is shown on the same scale in Figures 15(a), (b) and 16(a), (b). As shown in Figures 15(b) and 16(b), in both cases, the amplitude change ΔA increases when the molten metal contacts the thermocouple 81, as described above, and it can be seen that contact of the molten metal with the tip end surface 23 was detected. After that, over approximately 10 seconds, the amplitude change ΔA decreases to approximately the same value as before the molten metal contacted the tip end surface 23, suggesting that the molten metal separated from the tip end surface 23. Meanwhile, looking at the change in the heat transfer coefficient h, similar to the amplitude change ΔA, the heat transfer coefficient h increased sharply when the molten metal contacted the thermocouple 81. Then, over approximately 10 seconds, the heat transfer coefficient h decreased. Inferring from the change in amplitude ΔA and the change in heat transfer coefficient h that the state of the contact interface between the molten metal and the inner surface 75 of the steel plate 71 (corresponding to the tip surface 23 of the propagator 20) changed, it is believed that after the molten metal was poured, the molten metal came into contact with the inner surface 75, which allowed for good heat transfer, resulting in a high heat transfer coefficient h. However, after that, within a few seconds, the molten metal physically separated from the inner surface 75, which reduced heat transfer and lowered the heat transfer coefficient h.

[0110] In the casting process, the molten metal solidifies when it comes into contact with the mold and cools. It is well known that the solidification shrinkage (volume shrinkage) that occurs during this process physically separates the mold from the formed casting (molded product) that is formed by the solidification of the molten metal, creating a gap and reducing heat transfer (a decrease in the heat transfer coefficient h). Similarly, the results of the above experiment are thought to indicate that the solidification caused the casting to separate from the inner surface 75 of the steel plate 71, resulting in a decrease in the heat transfer coefficient h.

[0111] From Figures 15(b) and 16(b), it is apparent that the time-varying behavior of the amplitude change ΔA and the heat transfer coefficient h is similar, and it is predicted that there is a correlation between them. Figure 17 shows the relationship between the amplitude change ΔA and the heat transfer coefficient h. In Figure 17, data from two preheating temperatures of 160°C and 270°C are plotted on a single graph. The vertical axis showing the heat transfer coefficient in Figure 17 uses a logarithmic scale. As shown in Figure 17, there is a correlation between the amplitude change ΔA and the heat transfer coefficient h, and the heat transfer coefficient h can be approximated by the exponential function shown in Equation (5) below. Equation (5) is the same as Equation (2) above.

number

[0112] The reason for approximating with an exponential function as shown in equation (5) will be explained. Generally, when two objects come into complete contact and become one, the heat transfer coefficient at the contact interface between the two objects becomes infinite. In other words, the thermal resistance (equivalent to the reciprocal of the heat transfer coefficient) at the contact interface becomes zero. This is expected to cause the heat transfer coefficient to rise sharply in a region where there is a change in amplitude ΔA. For this reason, it is believed that approximating with an exponential function can appropriately represent the relationship between the change in amplitude ΔA and the heat transfer coefficient.

[0113] The amplitude change amount ΔA when the preheating temperature was 160°C was substituted into the above formula (5) to find the converted value of the heat transfer coefficient h. The accuracy of the approximation was confirmed from this converted value and the measured value of the heat transfer coefficient h obtained from the above-mentioned experiment. The accuracy of the approximation was also confirmed in the same way when the preheating temperature was 270°C. More specifically, |Converted value-Measured value| / Measured value When the relative average error is defined as the relative average error, the overall relative average error including the two preheating temperature conditions shown in Figure 17 was 21%. The average value of |Converted value-Measured value| was 3282 W / m 2 It was K.

[0114] The reason why there is a correlation between the amplitude change amount ΔA and the heat transfer coefficient h will be further explained below.

[0115] The inventors have reported that the heat transfer coefficient between the molten metal and the mold during the casting process is approximately linearly related to the pressure exerted by the molten metal when it comes into contact with the inner surface of the mold (see References 1 and 2). Reference 1 is "Terayama, Fuyama, Tsutsumoto, Shiga, Kobe, Okane, Yoshida, "Effect of Contact Pressure on the Heat Transfer Coefficient Between Molten Metal and the Mold in Aluminum Alloys," Japan Foundry Engineering Society, 180th National Conference Lecture Abstracts (2022) 110," and Reference 2 is JP 2022-151646 A.

[0116] Therefore, a compression experiment was carried out to examine the relationship between the pressure that the tip surface 23 of the propagating body 20 of the ultrasonic sensor 13 receives from the molten metal when it comes into contact with the molten metal and the amplitude change amount ΔA.

[0117] Figure 18 shows a schematic diagram of the compression experiment equipment. A 10.5 mm diameter cylindrical pipe was used as the propagating body 20 of the ultrasonic sensor 13. The cylindrical pipe was made of general structural rolled steel. The tip of the pipe was sealed with a 1 mm thick plate to form the tip surface 23. The propagating body 20 was placed vertically with the tip surface 23 facing upward. A graphite sheet 77 was placed between the lower surface and the stage 76 to stabilize the position of the ultrasonic sensor 13. Clay 78 was placed on the upper surface (tip surface 23) of the propagating body 20. A downward compressive load was applied from above through the clay 78 using a universal testing machine 79. While the compressive load was being applied, a burst signal containing multiple 41.9 kHz high-frequency guided waves was input to the transmitting coil 30 of the ultrasonic sensor 13, generating a resonant ultrasonic guided wave. The change in amplitude ΔA was calculated from the waveform of the output voltage generated by the receiving coil.

[0118] Figure 19 shows the relationship between the compressive load P and the amplitude change ΔA. Figure 19 shows that as the compressive load P increases, the amplitude change ΔA increases, and once the compressive load P reaches a certain level, the amplitude change ΔA remains almost constant. The load applied in this compression test is applied to the propagating body 20 of the ultrasonic sensor 13 through the clay 78. For this reason, the compressive load P can be considered as the pressure applied to the contact interface where the clay 78 and the ultrasonic sensor 13 are in contact.

[0119] From the above, it was found that the pressure received from an object in contact with the tip surface 23 of the ultrasonic sensor 13 changes exponentially with respect to changes in the amplitude change amount ΔA. On the other hand, as shown in the above-mentioned References 1 and 2, the heat transfer coefficient h between the molten metal and the mold in the casting process is linearly related to the pressure the mold receives from the molten metal in contact with the inner surface of the mold. As a result, it is thought that the heat transfer coefficient h between the molten metal and the mold in the casting process also changes exponentially with changes in the amplitude change amount ΔA, and that there is a correlation between the amplitude change amount ΔA and the heat transfer coefficient h.

[0120] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining the multiple components disclosed in the above-described embodiments. Some components may be omitted from all the components shown in each embodiment. [Explanation of symbols]

[0121] 1. Mold 2 through holes 3. Inner Surface 4 cavities 10 Molding material behavior detection device 11 Waveform generator 13 Ultrasonic Sensor 15 Output Processing Section 20 Propagation 21 Proximal end 22 Tip 23 Tip surface 30 Transmitting coil 31 Magnetostrictive body 32 receiving coil 33 Permanent magnets 41 Fourier transform section 42 Amplitude calculation section 43 Amplitude change amount calculation unit 44 Judgment section 45 Results Creation Department 50 Coefficient calculation section 51 Coefficient change amount calculation unit 52 Judgment section 53 Results Creation Department 60 Heat transfer coefficient calculation section 61 Results Creation Department

Claims

1. A molding material behavior detection device that detects the behavior of a molding material in a mold cavity during molding, a waveform generating unit that generates a waveform of an input voltage at a predetermined frequency; an ultrasonic sensor that generates an ultrasonic guided wave; an output processing unit; Equipped with The ultrasonic sensor includes a propagating body including a first portion located outside the mold and a second portion located in a through-hole that penetrates the mold, the propagating body being capable of propagating the guided wave that extends in a longitudinal direction from the first portion to the second portion; a transmitting coil located in the first portion, the transmitting coil generating an input magnetic field in response to the input voltage to propagate the guided wave to the propagating body; a receiving coil located in the first portion, the receiving coil generating an output voltage waveform in response to an output magnetic field generated based on the guided wave propagating through the propagating body; Including, the output processing unit processes the waveform of the output voltage to generate a detection result; the second portion includes a tip surface exposed to the cavity, The tip surface is located on the same plane as the inner surface of the mold, or is located more inward of the cavity than the inner surface. Molding material behavior detection device.

2. the ultrasonic sensor further includes a magnetostrictive body formed of a magnetostrictive material and located at the first portion of the propagating body, the magnetostrictive body receiving the input magnetic field from the transmitting coil to propagate the guided wave in the propagating body, and receiving the guided wave propagating within the propagating body to generate the output magnetic field toward the receiving coil. The molding material behavior detection device according to claim 1 .

3. The propagating body is formed of a metal material. The molding material behavior detection device according to claim 1 or 2.

4. the transmitting coil and the receiving coil are located at a base end of the first portion opposite to the second portion; The molding material behavior detection device according to claim 1 or 2.

5. The ultrasonic sensor further includes a permanent magnet attached to the propagating body, the permanent magnet is located on the opposite side of the second portion from the transmitting coil and the receiving coil; The molding material behavior detection device according to claim 1 or 2.

6. the waveform generating unit generates the input voltage at a resonant frequency of the propagating body; the output processing unit generates a detection result including a determination result of whether or not the molding material is in contact with the second portion of the propagating body based on a change in the waveform of the output voltage. The molding material behavior detection device according to claim 1 or 2.

7. The output processing unit includes a Fourier transform unit that Fourier transforms the waveform of the output voltage to create a frequency spectrum, an amplitude calculation unit that calculates an amplitude A at the resonance frequency from the frequency spectrum, and a reference amplitude A that is an amplitude at the resonance frequency obtained from the waveform of the output voltage when the molding material is not present in the cavity. ０ and the amplitude A, a determination unit that determines whether the molding material is in contact with the second portion of the propagating body based on the amplitude change ΔA; and a result creation unit that creates the detection result including the determination result by the determination unit. The molding material behavior detection device according to claim 6.

8. The output processing unit calculates an envelope of the waveform of the output voltage by: [Equation 1] a coefficient calculation unit that calculates the coefficient a when the molding material is not present in the cavity; ０ a coefficient change amount calculation unit that calculates a coefficient change amount Δa which is a difference between the coefficient a and the coefficient a; a determination unit that determines whether the molding material is in contact with the second portion of the propagating body based on the coefficient change amount Δa; and a result creation unit that creates the detection result including the determination result by the determination unit. The molding material behavior detection device according to claim 6.

9. The output processing unit includes a Fourier transform unit that Fourier transforms the waveform of the output voltage to create a frequency spectrum, an amplitude calculation unit that calculates an amplitude A at the resonance frequency from the frequency spectrum, and a reference amplitude A that is an amplitude at the resonance frequency obtained from the waveform of the output voltage when the molding material is not present in the cavity. ０ and the amplitude A, a heat transfer coefficient calculation unit that calculates a heat transfer coefficient between the molding material and the mold based on the amplitude change ΔA, and a result creation unit that creates the detection result including the heat transfer coefficient. The molding material behavior detection device according to claim 6.

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