JP2008114286A - Molten metal filling condition-determining apparatus in die casting machine, and molten metal filling condition good/bad judging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine the filling condition of molten metal regarding an injection sound whose difference between the case upon a normal time and the case upon an abnormal time has been able to be caught only by an expert heretofore, by catching the difference numerically. <P>SOLUTION: The molten metal filling condition-determining apparatus 50 in a die casting machine 1 comprises: a microphone 47 capable of detecting the sound pressure of an injection sound generated when molten metal is filled into cavities Ca in a pair of dies 102; and a controller 5 where the sound pressure of the injection sound detected by the microphone 47 and the prescribed set sound pressure are compared, and whether the filling condition of the molten metal is good or not is determined. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a molten metal filling state quality determination apparatus and a molten metal filling state quality determination method for a die casting machine.

  In casting by a die casting machine, a skilled person listens to an injection sound generated when a molten metal is filled in a mold cavity and determines whether or not filling has been performed normally.

In the molding of thermoplastic resin using an injection molding machine, as a versatile monitoring method that can be easily applied to a wide variety of injection molding machines, operation sound and vibration are detected by a microphone and an acceleration sensor, and the detected values are used as a basis. A method for monitoring the molding state is disclosed in Patent Document 1. Patent Document 1 discloses a method for monitoring abnormal insertion of an insert molding by collecting operation sounds generated from a mold with a microphone and monitoring the sound pressure level with respect to the mold periphery (Patent Patent 1). It has been suggested that the occurrence of an abnormality such as cracking of a molded product at the time of mold release can be monitored (paragraph 0020 of Patent Document 1).
Japanese Patent Laid-Open No. 05-50480

  In Patent Document 1, in the case of abnormal insertion of an insert molded product, abnormal noise with an abnormally large sound pressure level is detected, so that the occurrence of abnormality can be monitored. In Patent Document 1, in the case of cracking of a molded product at the time of mold release, it only suggests that the occurrence of an abnormality can be monitored, and a specific detection method is not described, but it is similar to the abnormal insertion of an insert molded product. Presumed to be a detection method.

  That is, in Patent Document 1, it is determined that an abnormality has occurred when an abnormal sound that is not normal but is generated only when there is an abnormality and anyone who is skilled in the art hears it is abnormal is detected.

  On the other hand, the injection sound in casting with a die-casting machine occurs in both normal and abnormal cases, and only an expert can determine whether the molten metal is normal or abnormal based on the subtle difference in sound. It is difficult to make a judgment while an inexperienced operator is still working.

  The object of the present invention is that, in casting with a die casting machine, conventionally, only an expert can grasp the difference between normal and abnormal times, numerically grasp the difference, and the state of molten metal filling An object of the present invention is to provide a molten metal filling state pass / fail judgment device and a molten metal filling state pass / fail judgment method capable of judging pass / fail.

  The molten metal filling state quality determination device of the present invention includes a detector capable of detecting a sound pressure of an injection sound generated when a molten metal is filled in a cavity of a mold, and a sound pressure of the injection sound detected by the detector. And a quality determination unit that compares the predetermined set sound pressure to determine quality of the molten metal filling state.

  Preferably, an emission sound generation determination unit that determines whether or not the sound pressure detected by the detector exceeds a predetermined emission sound generation determination threshold value, the quality determination unit is configured by the emission sound generation determination unit, The sound pressure detected by the detector during a predetermined set time after it is determined that the sound pressure detected by the detector has exceeded the emission sound generation determination threshold is set as the sound pressure of the emitted sound, and the sound pressure and the sound pressure The set sound pressure is compared to determine the quality of the molten metal filling state.

  Preferably, the predetermined set time is 0.01 seconds.

  Preferably, the quality determination unit has an abnormality in the filling state of the molten metal when the number of times the sound pressure of the emitted sound detected by the detector exceeds the set sound pressure exceeds a predetermined set number of times. judge.

  Preferably, an upper limit value and a lower limit value of a predetermined allowable range are set as the set sound pressure, and the pass / fail judgment unit determines that the average of the sound pressure peak values of the emitted sound detected by the detector is When it is not within the allowable range, it is determined that an abnormality has occurred in the molten metal filling state.

  Preferably, a frequency analysis unit that calculates a sound pressure at a predetermined frequency in the audible range of the emitted sound based on a temporal change in the sound pressure of the emitted sound detected by the detector, the pass / fail determination unit, The sound pressure at the predetermined frequency calculated by the frequency analysis unit is compared with the set sound pressure to determine whether the molten metal is filled.

  Preferably, the frequency analysis unit calculates sound pressures for a plurality of frequencies in the audible range of the emitted sound, and averages sound pressures in a predetermined frequency range among the calculated sound pressures for the plurality of frequencies. The sound pressure average value in the predetermined frequency range is calculated, and the quality determination unit compares the average value calculated by the frequency analysis unit with the set sound pressure to determine quality of the molten metal filling state. To do.

  Preferably, the frequency analysis unit calculates a sound pressure for each of a plurality of frequencies in the audible range of the emitted sound, and the pass / fail determination unit calculates the sound pressure calculated by the frequency analysis unit for each of the plurality of frequencies. Is compared with the set sound pressure to determine whether or not there is an abnormality for each frequency. When the number of frequencies determined to be abnormal exceeds a predetermined set number, it is determined that an abnormality has occurred in the molten metal filling state.

  Preferably, the pass / fail judgment unit compares the sound pressure calculated by the frequency analysis unit with the set sound pressure in a frequency range of 20 to 5000 Hz, and the sound pressure calculated by the frequency analysis unit is It is determined that an abnormality has occurred when the set sound pressure is exceeded.

  Preferably, an upper limit value and a lower limit value of a predetermined allowable range are set as the set sound pressure, and the pass / fail judgment unit has a sound pressure at the predetermined frequency calculated by the frequency analysis unit within the allowable range. It is determined that an abnormality has occurred in the molten metal filling state.

  Preferably, the information processing apparatus includes a notification unit that notifies that the abnormality determination unit determines that an abnormality has occurred.

  The method of determining whether or not the molten metal is filled in the die casting machine according to the present invention is such that the detector detects the sound pressure of the injection sound generated when the molten metal is filled into the cavity of the mold, and the detected sound pressure and a predetermined set sound. The quality of the molten metal filling state is determined by comparing the pressure.

  According to the present invention, in casting with a die-casting machine, conventionally, only an expert can grasp the difference between normal and abnormal injection sounds, numerically grasp the difference, the molten metal filling state Pass / fail can be determined.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a die casting machine 1 including a determination device 50 as a molten metal filling state pass / fail determination device according to a first embodiment of the present invention. However, in FIG. 1, only the main part with high relevance with the determination apparatus 50 among the die-casting machines 1 is shown.

  The die casting machine 1 is constituted by, for example, a horizontal horizontal injection type die casting machine. The die casting machine 1 injects molten metal into a cavity Ca formed by a pair of molds 102 and a mold clamping device (not shown) that holds a pair of molds 102 including a fixed mold 100A and a movable mold 100B, for example. An injection device 3 for filling, an unillustrated extrusion device for extruding a die-cast product molded in the cavity Ca from the fixed die 100A or the moving die 100B, and a control device 5 for controlling the operation of each of these devices are provided. Yes.

  The pair of molds 102 is provided with a chill vent 104 for venting the cavity Ca. The chill vent 104 includes, for example, a fixed side block 104a provided on the dividing surface of the fixed mold 100A and a moving side block 104b provided on the dividing surface of the moving mold 100B. The fixed block 104a and the movable block 104b have saw-tooth teeth that mesh with each other when the fixed mold 100A and the movable mold 100B are closed and clamped. The cavity Ca communicates with the outside of the pair of molds 102 through a gap between the sawtooth teeth, and gas is released from the gap between the sawtooth teeth.

  The mold clamping device is not particularly shown, but a fixed die plate that holds the fixed mold 100A, a movable die plate that holds the movable mold 100B, and a mold opening direction and mold closing with respect to the fixed die plate. And a drive mechanism that moves in the direction. The mold clamping device performs mold closing, mold opening, and mold clamping of the mold 102.

  The injection device 3 includes an injection sleeve 11 that communicates with the cavity Ca, an injection plunger 13 that pushes the molten metal in the injection sleeve 11 toward the cavity Ca, an injection cylinder 17 that drives the injection plunger 13, and a pressure oil in the injection cylinder 17. And a hydraulic circuit 25 for controlling supply or discharge of the gas.

  The injection sleeve 11 is formed in a substantially cylindrical shape, for example, and is fixed to the fixed mold 100A. The injection sleeve 11 has a hot water supply port 11 a for supplying molten metal into the injection sleeve 11. The molten metal is supplied to the hot water supply port 11a by, for example, a ladle (not shown).

  The injection plunger 13 has a plunger tip 13a fitted in the injection sleeve 11, and a plunger rod 13b having the plunger tip 13a fixed to the tip. As the plunger tip 13a slides in the injection sleeve 11 toward the cavity Ca, the molten metal in the injection sleeve 11 is injected into the cavity Ca and filled.

  The injection cylinder 17 is constituted by, for example, a hydraulic cylinder. The injection cylinder 17 includes a cylinder part 18, an injection piston 21 and a pressure-increasing piston 23 slidable in the cylinder part 18, and a piston rod 19 fixed to the injection piston 21.

  The cylinder portion 18 is formed in a substantially cylindrical shape, and has an injection cylinder chamber 18a and a pressure increasing cylinder chamber 18b. The pressure increasing cylinder chamber 18b is formed with a larger diameter than the injection cylinder chamber 18a. The pressure increasing cylinder chamber 18b is adjacent to the back side of the injection cylinder chamber 18a and communicates with the injection cylinder chamber 18a.

  The injection piston 21 is slidably provided in the injection cylinder chamber 18a. The pressure-increasing piston 23 includes a small-diameter portion 23a that can slide in the back side of the injection piston 21 in the injection cylinder chamber 18a, a large-diameter portion 23b that can slide in the pressure-increasing cylinder chamber 18b, and a small-diameter portion. 23a and the rod part 23c which fixes the large diameter part 23b.

  The injection piston 21 divides the injection cylinder chamber 18a into a first cylinder chamber 18c and a second cylinder chamber 18d. The large diameter portion 23b divides the pressure increasing cylinder chamber 18b into a third cylinder chamber 18e and a fourth cylinder chamber 18f. The small diameter portion 23a has one end facing the second cylinder chamber 18d and the other end facing the third cylinder chamber 18e.

  The injection piston 21 advances to the cavity Ca side when pressure oil is supplied to the second cylinder chamber 18d, and retreats when pressure oil is supplied to the first cylinder chamber 18c. The pressure-increasing piston 23 increases the pressure in the second cylinder chamber 18d by supplying pressure oil to the fourth cylinder chamber 18f, and reduces the pressure in the second cylinder chamber 18d by supplying pressure oil to the third cylinder chamber 18e. To do.

  The piston rod 19 has one end fixed to the injection piston 21 and the other end fixed to the plunger rod 13 b via the coupling 15.

  Although not particularly shown, the hydraulic circuit 25 is capable of supplying a hydraulic pressure source and pressure oil from the hydraulic pressure source to each of the first cylinder chamber 18c, the second cylinder chamber 18d, the third cylinder chamber 18e, and the fourth cylinder chamber 18f. Including a directional control valve for controlling the supply of pressure oil from each flow path to each cylinder chamber, a directional control valve for controlling the discharge of pressure oil from each cylinder chamber, and the like. It is possible to selectively supply pressure oil at a suitable pressure to each cylinder chamber and to selectively discharge pressure oil from each cylinder chamber.

  The control device 5 is constituted by a computer, for example. That is, a CPU 27 for performing various calculations, a ROM 29 for storing programs executed by the CPU 27, a RAM 31 as a working memory for the CPU 27, and an external storage device 33 for storing various programs and data are provided.

  In addition, the control device 5 includes a monitor 35 that displays an appropriate image based on a control signal from the CPU 27. The monitor 35 is composed of, for example, a liquid crystal display or a CRT display.

  The CPU 27 outputs a control signal for controlling the operation of each part such as the mold clamping device, the injection device 3, the extrusion device, and the monitor 35 based on signals from various sensors provided in the die casting machine 1. .

  For example, the die casting machine 1 includes, as various sensors, a position sensor 41 that detects the position of the piston rod 19, a first pressure sensor 43 that detects the pressure in the first cylinder chamber 18c, and a first sensor that detects the pressure in the second cylinder chamber 18d. 2 includes a pressure sensor 45, a mold 102 and / or a microphone 47 that detects sound from the injection sleeve 11.

  The position sensor 41 is composed of an appropriate type of position sensor such as a magnetic linear sensor, for example. The position sensor 41 outputs an electrical signal corresponding to the position of the piston rod 19 to the CPU 27. Since the piston rod 19 and the injection plunger 13 are fixed to each other, the detection position of the position sensor 41 may be referred to as the position of the injection plunger 13 below. The control device 5 can calculate the speed of the injection plunger 13 by differentiating the position detected by the position sensor 41. The control device 5 controls the speed of the injection plunger 13 based on the position detected by the position sensor 41.

  The first pressure sensor 43 and the second pressure sensor 45 are constituted by pressure sensors of an appropriate type such as a diaphragm type pressure sensor, for example. The first pressure sensor 43 and the second pressure sensor 45 output an electrical signal corresponding to the pressure received from the pressure oil to the CPU 27. The control device 5 can calculate the force that the injection piston 21 receives from the pressure oil based on the pressures detected by the first pressure sensor 43 and the second pressure sensor 45. The control device 5 calculates and controls the cylinder pressure and the like based on the pressures detected by the first pressure sensor 43 and the second pressure sensor 45. The cylinder pressure is a pressure (plunger pressure) that acts on the molten metal from the plunger tip 13a, which is calculated based on the pressure oil pressure.

  The microphone 47 is composed of an appropriate type of microphone such as a dynamic microphone, a condenser microphone, or a ribbon microphone. The microphone 47 outputs an electric signal having a voltage corresponding to the sound pressure (instantaneous sound pressure) of the received sound to the CPU 27 continuously or intermittently. In addition, since the frequency of the sound received by the microphone 47 is specified based on the frequency of the electric signal from the microphone 47, the microphone 47 can be regarded as detecting the frequency of the sound.

  For example, the microphone 47 is disposed on the chill vent 104 side in the periphery of the mold 102, in other words, on the innermost side of the cavity Ca. Further, the microphone 47 is arranged with the sound collecting direction facing the mold 102. The control device 5 samples the electrical signal from the microphone 47 at a predetermined sampling period, and determines whether the molten metal is filled based on the sound pressure detected by the microphone 47. The microphone 47 and the control device 5 can detect and process sound in the audible range (20 to 20000 Hz).

  The determination device 50 includes the control device 5 and the microphone 47.

  The operation of the above die casting machine 1 will be described.

  In the die casting machine 1, a molding cycle for casting a die cast product is repeatedly executed. In each molding cycle, a pretreatment process for applying a release agent or the like to the fixed mold 100A and the moving mold 100B, a mold closing process for closing the fixed mold 100A and the movable mold 100B that have been pretreated, a mold A mold clamping process for clamping a pair of closed molds 102, an injection process for injecting and filling molten metal into the cavity Ca of the molds 102 that have been clamped, and a mold 102 is molded after the filled melt has solidified. A mold opening process for opening, an extrusion process for extruding a die-cast product from the fixed mold 100A or the moving mold 100B that has been opened, a post-processing process for cleaning the fixed mold 100A and the moving mold 100B, and the like are included.

  FIG. 2 is a flowchart showing a procedure of injection control processing executed by the control device 5 in the injection process.

  In step S1, the control device 5 outputs a control signal to the hydraulic circuit 25 so as to start low-speed injection. Thereby, the pressure oil is supplied to the second cylinder chamber 18d, and the advancement of the injection plunger 13 is started. However, the forward speed of the injection plunger 13 is controlled to be relatively low in order to prevent the molten metal in the sleeve from entraining air.

  In step S2, the control device 5 determines whether or not the injection plunger 13 has reached a predetermined high-speed switching position based on the position detected by the position sensor 41, and continues low-speed injection until it is determined that the injection plunger 13 has reached. If it is determined that the high speed switching position has been reached, a control signal is output to the hydraulic circuit 25 so as to start the high speed injection by switching the plunger speed to a high speed (step S3). That is, a control signal is output to the hydraulic circuit 25 so as to increase the amount of pressure oil supplied to the second cylinder chamber 18d.

  In step S4, the control device 5 determines whether or not the boosting start condition is satisfied, and continues high-speed injection until it is determined that the boosting start condition is satisfied. The pressure increase start condition is, for example, that the surge pressure is detected based on the pressure detected by the first pressure sensor 43 and the second pressure sensor 45, and the injection plunger 13 is at a predetermined position based on the position detected by the position sensor 41. It is detected that it has been reached.

  When determining that the boosting start condition is satisfied, the control device 5 commands the boosting start (step S5). That is, a control signal is output to the hydraulic circuit 25 so that pressure oil is supplied to the fourth cylinder chamber 18f.

  In step S6, the control device 5 determines whether or not the pressurization of the molten metal has been started. For example, it is determined whether the cylinder pressure calculated based on the pressures detected by the first pressure sensor 43 and the second pressure sensor 45 has started to rise. When determining that the boosting has started, the control device 5 starts measuring the boosting time (step S7).

  In step S8, the control device 5 determines whether or not the cylinder pressure has reached the casting pressure (final pressure), and waits until it is determined that the cylinder pressure has been reached. When it is determined that the cylinder pressure has reached the casting pressure, the control device 5 ends the measurement of the pressure increase time (step S9). In addition, the control operation is output to the hydraulic circuit 25 so as to end the pressure increasing operation and perform the pressure holding operation (step S10).

  The control device 5 manages the high-speed switching position (step S2), the high-speed speed (steps S3 to S4), the pressurization time (steps S7 and S9), and the cylinder pressure (casting pressure, step S8). Perform discrimination and feedback control. For example, the measured pressure increase time or high speed is compared with these target values, and if the difference is large, it is determined that an abnormality has occurred. In addition, the supply amount of pressure oil is controlled during the measured molding cycle or in the next molding cycle so that the measured pressurization time and high-speed speed approach these target values.

  However, the high-speed switching position, high-speed speed, pressurization time, and cylinder pressure are measured via the plunger rod 13b, and even if these are controlled to the target values, the desired pressure is actually transmitted to the molten metal. I don't know if it is. Therefore, even if an abnormality actually occurs in the mold, the control device 5 may determine that the product is a non-defective product. Further, when a temperature sensor or a pressure sensor is provided in the mold and the mold temperature and the molten metal pressure are directly measured and managed, the cost increases because the mold itself must be crafted.

  Therefore, the die casting machine 1 determines the quality of the die cast product based on the loudness (sound pressure) detected by the microphone 47. Specifically, it is as follows.

  Note that the sound pressure may be positive or negative depending on an index representing the sound pressure (for example, instantaneous sound pressure), but the absolute value of the index is related to the volume of the sound. The term “sound pressure” or “sound pressure level” may refer to the absolute value of the index.

  3 and 4 show a predetermined period before and after the molten metal is filled into the mold cavity, that is, after the high-speed injection is started (after step S3) until the pressurization is finished (step S8). It is a graph which shows the instantaneous sound pressure which the microphone 47 detected in the period. 3 and 4, the horizontal axis represents time, and the vertical axis represents sound pressure.

  3 and 4 are instantaneous sound pressures actually measured in the experiment. For reference, numerical values are described on the horizontal axis and the vertical axis, but the present invention is not limited to those in which sound pressure is measured in such a numerical range. For example, the magnitude of the instantaneous sound pressure changes depending on the distance between the microphone 47 and the mold 102.

  FIG. 3 shows a measurement result when a non-defective product is cast. FIG. 4 shows a measurement result when a defective product is cast. Specifically, FIG. 4 shows a measurement result when the chill vent 104 is closed, the gas escape is worsened, and the die-cast product is swollen.

  In FIG. 3, the sound pressure suddenly increases near the dotted line L1 and in FIG. 4 near the dotted line L1 '. This indicates that when the molten metal is filled in the cavity Ca of the mold 102, an injection sound is generated which is generated using the cavity Ca as a sound source.

  In the present application, filling does not mean a state in which the cavity Ca is filled with molten metal (a state in which there is no gas in the cavity Ca). Filling of the present application includes filling the molten metal in a vacant area except for a portion occupied by the gas when gas is poor and gas remains in the cavity Ca. Even in this case, as shown in FIG.

  It is difficult to specify the generation timing of the injection sound based on the position of the injection plunger 13 or the like due to the hot water supply error of the molten metal or the control error of the hydraulic circuit 25. However, as can be understood from FIGS. 3 and 4, whether or not the emission sound is generated can be determined by whether or not the detected sound pressure exceeds the emission sound generation determination threshold value Pt.

  The emission sound generation determination threshold value Pt represents a change in sound pressure detected by the microphone 47 during a predetermined period after the high-speed injection is started (after step S3) until the pressure increase is ended (step S8). By analyzing based on at least one of the case where a non-defective product and a defective product are cast, a range that is larger than the amplitude of the sound pressure before it suddenly increases and smaller than the amplitude of the sound pressure that suddenly increased Therefore, it may be set appropriately. The amplitude ranges from a reference sound pressure (for example, 0) to a positive or negative pole (a positive pole when a positive value such as effective sound pressure is used as an index representing the sound pressure). It is.

  When FIG. 3 is compared with FIG. 4, when a defective product is cast, the sound pressure is increased immediately after the injection sound is generated, compared to when a good product is cast. Accordingly, whether or not the filling state is good is determined by determining whether or not the sound pressure detected by the microphone 47 exceeds the predetermined set sound pressure until the predetermined set time To elapses after the emission sound is generated. Can be done.

  The set sound pressure Ps is compared with the sound pressure when a defective product is cast and the sound pressure when a non-defective product is cast after the generation of the injection sound, and from the amplitude of the sound pressure when the defective product is cast. May be set appropriately within a range that is smaller and larger than the amplitude of the sound pressure when a non-defective product is cast.

  The set time To compares the sound pressure when a defective product is cast with the sound pressure when a good product is cast after the injection sound is generated, and the amplitude of the sound pressure when the defective product is cast is good. May be set appropriately within a range that is larger than the amplitude of the sound pressure when the is cast. For example, in the measurement data of FIGS. 3 and 4, about 0.01 seconds is appropriate. After 0.01 seconds, the sound pressure starts to converge even when a defective product is cast, and there is almost no difference from the case where a good product is cast.

  FIG. 5 is a flowchart illustrating a procedure of a quality determination process executed by the control device 5 in order to realize the quality determination of the filling state based on the emission sound as described above. For example, this process is performed in real time in parallel with the injection control of FIG. 2 in each molding cycle.

  In the following processing, appropriate indicators such as instantaneous sound pressure, effective sound pressure, and sound pressure level may be used as an index representing sound pressure. However, as an example, a case where instantaneous sound pressure is used will be described.

  In step S <b> 21, the control device 5 determines whether or not an emission sound generation determination start condition is satisfied, waits until it is determined to be satisfied, and proceeds to step 22 when it is determined that it is satisfied. As described above, the control device 5 detects the occurrence of the emitted sound depending on whether or not the detected sound pressure detected by the microphone 47 exceeds the emitted sound generation determination threshold value Pt. However, there is a possibility that a sound other than the emitted sound having a high sound pressure is detected by the microphone 47 and a sound other than the emitted sound is erroneously detected as the emitted sound. Therefore, in order to eliminate such a risk, it is determined whether or not a process that may generate a sound having a higher sound pressure than the emitted sound has been completed. To start. The determination start condition for the generation of the injection sound is, for example, that the position of the injection plunger 13 detected by the position sensor 41 has reached the high speed switching position (proceeding to step S3), or that low speed injection has started (step S1). ), Mold clamping or mold closing has been completed.

  In step S22, as described above, the control device 5 determines whether or not the detected sound pressure exceeds the emission sound generation determination threshold value Pt, and waits until it is determined that it has exceeded. move on.

  In step S23, as described above, time measurement is started in order to make a pass / fail determination based on the sound pressure at the set time To from the emission sound generation, among the detected sound pressures.

  In step S24, it is determined whether or not the detected sound pressure exceeds the set sound pressure Ps. When it is determined that the detected sound pressure exceeds the set sound pressure Ps, 1 is added to the number of detections indicating that the set sound pressure Ps has been exceeded (step S25), and the process proceeds to step S26. If it is not determined that the sound pressure has exceeded the set sound pressure Ps, step S25 is skipped and the process proceeds to step S26.

  Note that the determination as to whether the detected sound pressure exceeds the set sound pressure Ps is performed for each wavelength or half wavelength. For example, the time point at which the sign of the change rate of the sound pressure is reversed is specified, the sound pressure at the specified time point is specified as the amplitude, and the specified amplitude is compared with the set sound pressure Ps. In addition, it is determined whether or not zero crossing has been performed, and determination is performed for each wavelength or half wavelength.

  In step S26, the control device 5 determines whether or not the time being measured has reached the set time To. If it is not determined that it has arrived, the process returns to step S24. If it is determined that it has arrived, the process proceeds to step S27.

  In step S27, the control device 5 determines whether or not the number of detections indicating that the detected sound pressure exceeds the set sound pressure Ps exceeds a predetermined set number. If it is determined that it has exceeded, a predetermined abnormal process is executed (step S28), and then the process ends. If it is determined that it has not exceeded, step S28 is skipped and the process is terminated.

  For example, the abnormal time process is a process for notifying a worker that an abnormality has occurred, and a die-cast product extruded from the fixed mold 100A or the moving mold 100B in the extrusion process, separately from the non-defective product. Are a process for controlling a conveyance device (not shown) and a process for stopping the molding cycle. The notification process includes, for example, a process for displaying a predetermined image indicating that an abnormality has occurred on the monitor 35, a process for outputting a predetermined notification sound indicating that an abnormality has occurred from a speaker (not shown), an abnormality This is a process of recording information indicating that the occurrence has occurred in the external storage device 33.

  Since it is determined whether or not the instantaneous sound pressure exceeds the set sound pressure Ps during the set time To, the sampling of the instantaneous sound pressure is a cycle shorter than the set time To (for example, 0.01 seconds). Needs to be done. Further, as shown in FIG. 5, when each process such as steps S21 to S26 is executed simultaneously with the measurement, each process needs to be executed in a time shorter than the set time To. The sound pressure measurement by the microphone 47 may be performed only during the minimum necessary period, that is, between step S21 and step S26, or may be performed during a wider period including that period.

  The injection sound generation determination threshold value Pt, the set sound pressure Ps, the set time To, and the set number of times may be set by the manufacturer of the die casting machine 1 (determination device 50) or can be set by the user of the die casting machine 1. Also good.

  According to the first embodiment described above, the determination device 50 of the die casting machine 1 includes the microphone 47 that can detect the sound pressure of the emitted sound that is generated when the molten metal is filled in the cavity Ca of the mold 102, and the microphone. Since the control device 5 for comparing the sound pressure of the detected injection sound 47 and the set sound pressure Ps to determine the quality of the molten metal filling state is provided, only the skilled person has been normal and abnormal in the past. It is possible to judge the quality of the molten metal filling state by numerically grasping the difference in the injection sound that can grasp the difference with time.

  The above-described determination method based on sound pressure is used as a conventional method for determining the quality of die casting products by comparing measured values such as injection plunger speed (for example, high speed speed), cylinder pressure, pressure increase time, etc. with reference values. In addition, the accuracy of product quality determination is improved.

  The control device 5 determines whether or not the sound pressure detected by the microphone 47 exceeds the emission sound generation determination threshold value Pt, and the set time after it is determined that the sound pressure detected by the microphone 47 exceeds the emission sound generation determination threshold value Pt. The sound pressure detected by the microphone 47 during To is used as the sound pressure of the emitted sound, and the quality of the molten metal is determined by comparing the sound pressure of the emitted sound with the set sound pressure Ps. Can be detected appropriately, and the influence of other sounds after the emission sound is generated can be eliminated from the detected sound pressure that contributes to pass / fail determination. Therefore, the accuracy of the quality determination based on the emission sound can be improved.

  Since the control device 5 determines that an abnormality has occurred in the molten metal filling state when the number of times that the sound pressure amplitude of the emitted sound detected by the microphone 47 exceeds the set sound pressure Ps exceeds a predetermined set number of times, It is possible to prevent a determination error that occurs when a sound other than an emitted sound with a high sound pressure is detected by the microphone 47 due to some accidental factor.

(Second Embodiment)
The mechanical configuration of the molten metal filling state pass / fail judgment device according to the second embodiment of the present invention is the same as that of the first embodiment. That is, the molten metal filling state pass / fail determination apparatus according to the second embodiment includes the control device 5 and the microphone 47 provided in the die casting machine 1 as shown in FIG. Also in the second embodiment, the die casting machine 1 performs the same molding cycle and injection process as those in the first embodiment described with reference to FIG.

  However, in the second embodiment, the control device 5 executes a pass / fail determination process different from the pass / fail determination process of the first embodiment described with reference to FIG.

  In the first embodiment, since the emitted sound becomes loud when the chill vent 104 is closed, the occurrence of abnormality is determined based on whether the emitted sound exceeds the set sound pressure Ps. However, depending on the type of abnormality, the emitted sound may be smaller than normal. Therefore, in the second embodiment, the control device 5 executes a quality determination process that can detect an abnormality in which the emission sound is smaller than normal.

6 and 7 illustrate the determination process according to the second embodiment. The time series change of the instantaneous sound pressure shown in FIGS. tolerance of _RP and negative P _{RN (hereinafter,} simply referred to as "tolerance P _R", may not distinguish between the two.) shows with.

Tolerance _{P RP} of the positive is defined by the lower limit value _{P LPD} of the positive upper limit value _{P LPU} and positive side. Negative tolerance _{P RN} is defined by the lower limit value _{P LND} upper limit _{P LNU} and the negative side of the negative side. Hereinafter, it is simply referred to as “upper limit value P _LU ” or “lower limit value P _LD ”, and the positive side and the negative side may not be distinguished.

The control device 5 is referred to as a positive-side peak value P _PP and a negative-side peak value P _PN (hereinafter simply referred to as “peak value P _P ”) of the instantaneous sound pressure of the detected emission sound, and sometimes does not distinguish between them. ). Then, the average value of the positive peak value _{PPP and} the average value of the negative peak value _PPN are calculated.

The control device 5 determines whether or not the average value of the positive peak value _PP is within the allowable range P _RP and / or whether the average value of the negative peak value P _PN is within the allowable range P _RN . Determine whether or not. Then, it is determined that the average value is not within the allowable range P _R, abnormality occurs.

The peak value P _PP of the positive is the sound pressure of the point sound pressure is switched from increase to decrease, the peak value P _PN of the negative side, the sound pressure of the point sound pressure is switched from decrease to increase is there. That is, the peak value P _P is the sound pressure at which the sign of the change rate of the detected sound pressure is reversed. However, to the sound push all may be used as the peak value P _P when the sign of the rate of change of the sound pressure is reversed, of the sound pressure when the sign of the rate of change of the sound pressure is reversed, a predetermined condition only the sound pressure may be used as the peak value P _P satisfying.

For example, the control device 5 sequentially specifies and stores the sound pressure when the sign of the rate of change of the detected sound pressure is reversed from the start of the emitted sound on each of the positive side and the negative side. Then, on each of the positive side and the negative side, after the stored number reaches the predetermined set number, the absolute value of the sound pressure when the sign of the newly detected change rate is inverted is stored. Only when the absolute value of the sound pressure is larger than the absolute value of the smallest sound pressure, the sound pressure when the sign of the newly detected change rate is inverted is stored instead of the smallest sound pressure. To do. Then, using acoustic pressure setting number being finally stored in the injection sound ends as the peak value P _P. By doing so, by suppressing the influence of the inversion of the sign of the rate of change caused by microscopic variations due to noise or the like, it can improve the detection accuracy of the peak value P _P. Other, or perform appropriate filtering may be such as to detect the peak value P _P every half wave on the basis of the zero-crossing decision.

The average value of the peak values P _P may be calculated using all the peak values P _P of the specified injection sound, appropriately selecting a plurality of peak values P _P from all the peak values P _P identified it may be calculated using the selected peak value P _P.

When calculating the average value of a plurality of peak values P _P selectively using, the selection method may as an appropriate method. For example, of all the peak values P _P identified may calculate the average value by excluding a predetermined number of peak values P _P of a predetermined number of more peak values P _P and / or smaller from the larger. Further, for example, the mean value and standard deviation of all the peak values P _P identified by one calculation, to identify the normal distribution of the peak values P _P based on the average value and standard deviation, generated based on the normal distribution probability calculating the range of the peak values P _P equal to or less than a predetermined value may be calculated again average value by excluding the peak values P _P within that range.

Upper limit value P _LU and the lower limit value P _LD tolerance P _R are included the average value of the peak values P _P when good is cast, the average value of the peak values P _P when the defective is cast You may set suitably based on experiment etc. so that it may not be included.

For example, when the good is cast, the average value of the peak value P _PP of positive calculated as described above, the reference value P _PPS of the average value of the peak value P _PN of the negative side the positive side of the allowable range P _RP , A reference value P _PNS (hereinafter, simply referred to as “reference value P _PS ”, the positive side and the negative side may not be distinguished) of the allowable range P _{RN on} the negative side, and predetermined with respect to the reference value P _PS by setting the allowable range may be set an upper limit value P _LU and the lower limit value P _LD. In this case, as the reference value P _PS, may be using the average value of the peak value P _PP in a single casting, the average value of the peak value P _PP in a single casting, averaged for a plurality of times of casting, A plurality of average values of the peak values _PPP may be used, such as using an average value of the average values. In addition, the allowable width may be set separately on the positive side, the negative side, the upper limit side, and the lower limit side, or may be set in common in any one of them. The allowable range, for example, the average value of the peak value P _PP of the positive side in a single casting when good is cast, to calculate the standard deviation of the plurality of times of casting, as appropriate to the standard deviation or standard deviation A product obtained by multiplying an appropriate correction coefficient may be used.

  FIG. 8 shows the procedure of the pass / fail determination process executed by the control device 5 to realize the pass / fail determination of the filling state based on whether or not the sound pressure of the emitted sound is within a predetermined allowable range. It is a flowchart. For example, this process is performed in real time in parallel with the injection control of FIG. 2 in each molding cycle.

  Steps S51 to S53 are the same as steps S21 to S23 in FIG. 5, and step S54 is the same as step S26 in FIG. Accordingly, in steps S51 to S54, a predetermined set time To (for example, 0.01 seconds) elapses from the time when the sound is generated (when the absolute value of the instantaneous sound pressure exceeds the sound generation determination threshold value Pt). The instantaneous sound pressure is measured.

In step S55, the controller 5 specifies the peak value P _P of the positive and / or negative side. In step S56, it calculates the average value of the peak values P _P of the positive and / or negative side. Then, in step S57, the determining whether the average value thereof calculated or within an acceptable range P _R.

The control device 5, when the average value is determined not to be within the allowable range P _R, after it proceeds to step S58, the ends the process. If the average value is determined to be within the allowable range P _R, and ends the processing skips step S58. Step S58 is the same process as step S28 of FIG.

Incidentally, an injection sound generated determination threshold Pt, _(at least one of the tolerance upper limit value defining the P _R, the lower limit value, the reference value such as a parameter), set time To allowable range P _R die casting machine 1 (determination unit 50) may be set by the manufacturer, or may be set by the user of the die casting machine 1. In addition, it is selected by the user of the die casting machine 1 whether to determine for both the positive side and the negative side or whether to determine for either the positive side or the negative side when determining only one of the positive side and the negative side It may be possible.

  According to the above 2nd Embodiment, there exists an effect similar to 1st Embodiment. That is, it is possible to determine the quality of the molten metal filling state by numerically grasping the difference in the injection sound that only a skilled person can grasp the difference between normal and abnormal.

Further, the peak value P _P is, since performing quality determination by checking the allowable range P _R in whether defined by the upper limit value P _LP and the lower limit value P _LN, not only the abnormality emitted sound increases, the injection sound Smaller abnormalities can also be detected. Peak value P _P is the allowable range P _R in determining whether or not, from doing using the average value of the peak values P _P, the effects of large or small peak value P _P, which accidentally caused by noise or the like This can be eliminated and the accuracy of pass / fail judgment is improved. By determining whether the positive side or the negative side is good or bad, more accurate determination is expected.

(Third embodiment)
The mechanical configuration of the molten metal filling state pass / fail determination apparatus according to the third embodiment of the present invention is the same as that of the first embodiment. That is, the molten metal filling state pass / fail determination apparatus according to the third embodiment includes the control device 5 and the microphone 47 provided in the die casting machine 1 as shown in FIG. Also in the third embodiment, the die casting machine 1 performs the same molding cycle and injection process as those of the first embodiment described with reference to FIG.

  However, in the third embodiment, the control device 5 executes a quality determination process different from the quality determination process of the first embodiment described with reference to FIG.

  FIG. 9 shows the measurement result of the instantaneous sound pressure of the injection sound when the non-defective product is cast, and the measurement result of the instantaneous sound pressure of the injection sound when the defective product is cast by blocking the chill vent. Is a graph showing time-series data of instantaneous sound pressures subjected to Fourier transform. That is, FIG. 4 is a graph showing 10 time series data of instantaneous sound pressure similar to FIG. 3 and 10 time series data of instantaneous sound pressure similar to FIG. The horizontal axis represents frequency (Hz), and the vertical axis represents sound pressure level (dB). FIG. 9 shows the analysis results in a range including the audible range (20 to 20000 Hz). Note that, as shown in FIGS. 3 and 4, the time range subjected to Fourier transformation is 0.01 seconds from the time when the emission sound is generated (the time when the absolute value of the instantaneous sound pressure exceeds the emission sound generation determination threshold value Pt). Until later.

  For reference, numerical values are written on the horizontal axis and the vertical axis in FIG. 9 and the like, and in the following description, for ease of understanding, the illustrated numerical values are referred to. It is not limited to a numerical range. For example, the frequency characteristics of the injection sound during good product casting and defective product casting vary depending on the shape of the cavity Ca and the like.

  As shown in FIG. 9, when viewed over the entire audible range, the sound pressure level at the time of casting good products and the sound pressure level at the time of casting defective products are generally at the same level. Therefore, it can be said that it is difficult to hear the difference unless it is an expert.

  Microscopically, when the frequency is in the range of 0 to 5000 Hz, the sound pressure level at the time of defective casting tends to be higher than the sound pressure level at the time of casting good, and in the range of 5000 to 20000 Hz, the casting is good. The sound pressure level at the time tends to be higher than the sound pressure level at the time of casting defective products. In both good casting and defective casting, the sound pressure level in the frequency range of 0 to 5000 Hz tends to be higher than the sound pressure level in the frequency range of 5000 to 20000 Hz.

  Incidentally, in the frequency range of 5000 to 20000 Hz, the raw sound pressure shown in FIGS. 3 and 4 is used even though the sound pressure level at the time of good product casting tends to be higher than the sound pressure level at the time of defective product casting. In (additional sound pressure of all frequencies), the sound pressure during defective casting is greater than that during good casting because the sound pressure level in the frequency range of 0 to 5000 Hz is in the frequency range of 5000 to 20000 Hz. This is thought to be due to the tendency to be higher than the sound pressure level.

  FIG. 10 is a diagram illustrating a frequency range of 0 to 5000 Hz among the frequency analysis results illustrated in FIG. 9. FIG. 10 shows that there is a clear difference in sound pressure level between defective casting and non-defective casting at around 1000 Hz.

  FIG. 11A is a diagram illustrating a frequency range of 900 to 1050 Hz among the frequency analysis results illustrated in FIG. 10. As shown in FIG. 11 (a), the sound pressure level at the time of non-defective product casting and the sound pressure level at the time of defective product casting have different existence ranges in a predetermined frequency range. That is, the sound pressure level when casting good products is smaller than about 60 dB, and the sound pressure level when casting defective products is larger than about 60 dB.

  FIG. 11B shows the frequency ranges (900 to 900) shown in FIG. 11A for each of the 10 measurement results at the non-defective casting shown in FIG. 11A and the 10 measurement results at the defective casting. 1050 Hz) is a graph showing an averaged sound pressure level. The horizontal axis indicates the number of measurements 20 times (10 times when casting good products, 10 times when casting defective products), and the vertical axis is the sound pressure level (dB).

  As shown in FIG. 11 (b), even when the sound pressure levels are averaged in a predetermined frequency range, the sound pressure level at the time of non-defective casting is different from the sound pressure level at the time of defective casting. Yes. Moreover, by averaging, the fluctuations in the sound pressure level with respect to the frequency as shown in FIG. 11 (a) are leveled, and the difference between the sound pressure level at the time of non-defective casting and the sound pressure level at the casting of defective products is greater. It is clear.

  As described above, whether or not the molten metal is filled is determined by comparing the detected sound pressure at a predetermined frequency of the emitted sound with the set sound pressure and determining that an abnormality has occurred when the detected sound pressure exceeds the set sound pressure. Is possible. Therefore, in the first embodiment, the sound pressure given in time series (time domain) is compared with the set sound pressure, whereas in the third embodiment, the sound pressure given in the frequency domain and the set sound pressure are compared. And compare.

  FIG. 12 is a flowchart showing the procedure of the pass / fail determination process executed by the control device 5 in order to realize the pass / fail determination of the filling state based on the detected sound pressure at the predetermined frequency of the emitted sound as described above. For example, this process is performed in real time in parallel with the injection control of FIG. 2 in each molding cycle.

  Steps S31 to S33 are the same processes as steps S21 to S23 of FIG. 5, and step S34 is the same process as step S26 of FIG. Accordingly, in steps S31 to S34, a predetermined set time To (for example, 0.01 seconds) elapses from the time when the sound is generated (when the absolute value of the instantaneous sound pressure exceeds the sound generation determination threshold value Pt). The instantaneous sound pressure is measured.

  In step S35, Fourier transformation is performed on the time-series data of the instantaneous sound pressure acquired in steps S31 to S34, and the sound pressure for each frequency is calculated. The Fourier transform is performed by, for example, FFT (Fast Fourier Transform). In the Fourier transform, various processes for improving calculation accuracy such as multiplication by a window function or various filter processes may be performed.

  The sampling of the instantaneous sound pressure needs to be performed at a cycle in which the sound pressure in a desired frequency or a desired frequency range can be calculated by Fourier transform. For example, if the sampling period of instantaneous sound pressure is Δt, the frequency range in which the sound pressure for each frequency is calculated by FFT is 0 to 1 / (2Δt), so the maximum value of the desired frequency range is 1 / ( Δt must be set to be 2Δt) or less. For example, as shown in FIG. 11A, if it is desired to calculate a sound pressure of 1050 Hz or less, Δt needs to be 1/2100 seconds (about 0.0005 seconds) or less.

  The frequency increment Δf when the sound pressure for each frequency is calculated by FFT is 1 / To. For example, if To is 0.01 seconds, Δf is 100 (Hz). Therefore, when it is desired to calculate the sound pressure for more frequencies in the desired frequency range, for example, it is necessary to lengthen To or perform interpolation calculation based on the calculated sound pressure for each frequency. Note that FFT analyzers that can calculate the sound pressure at each frequency with a frequency step Δf smaller than 1 / To by improving the FFT method or performing interpolation calculation are commercially available and well known. Various methods can be selected to make the frequency step Δf smaller than 1 / To, and even in commercially available FFT analyzers, the method differs depending on the company, but when determining the set sound pressure for pass / fail judgment, pass / fail judgment If the method is the same as when performing the above, it is considered that the determination accuracy is not lowered by interpolation calculation or the like. In the third embodiment, since the quality is determined based on the sound pressure for each frequency, even if the sound after the emitted sound is mixed with the time series data of the instantaneous sound pressure by increasing To, the emitted sound If the frequency range between the sound and the sound after the emission sound is different, the error is not expanded.

  In the Fourier transform, if the Fourier transform calculates a so-called power spectrum, the instantaneous sound pressure squared per unit time is calculated. Therefore, the square root of the calculated value is equivalent to the effective sound pressure for each frequency from the unit viewpoint. Further, 20 times the logarithm with the ratio of the effective sound pressure to the reference effective sound pressure as the base is equivalent to the sound pressure level for each frequency from the unit viewpoint. In the following processing, any of the values obtained by Fourier transform, the effective sound pressure, and the sound pressure level may be used. Therefore, these are not distinguished and are collectively referred to as sound pressure or detected sound pressure. To do.

  In step S36, the control device 5 averages the detected sound pressure for each frequency obtained in step S35 for a predetermined frequency range. For example, the detected sound pressure for each frequency of 900 to 1050 Hz shown in FIG. 11 is averaged.

  In step S37, the control device 5 determines whether or not the average of the detected sound pressures calculated in step S36 exceeds the set sound pressure. The set sound pressure is set to 65 dB, for example, based on the experimental result of FIG.

  When it is determined that the average detected sound pressure exceeds the set sound pressure, the control device 5 proceeds to step S38 and ends the process. If it is determined that it has not exceeded, step S38 is skipped and the process is terminated. Step S38 is the same process as step S28 of FIG.

  The Fourier transform may be realized by storing an FFT program in the external storage device 33 of the control device 5 or may be realized by incorporating a commercially available FFT analyzer in the control device 5.

  The emission sound generation determination threshold, the set sound pressure, the set time, and the frequency range to be averaged may be set by the manufacturer of the die casting machine 1 (determination device 50) or set by the user of the die casting machine 1. There may be.

  According to the above 3rd Embodiment, there exists an effect similar to 1st Embodiment. That is, it is possible to determine the quality of the molten metal filling state by numerically grasping the difference in the injection sound that only a skilled person can grasp the difference between normal and abnormal.

  The control device 5 calculates the sound pressure at a predetermined frequency in the audible range of the emitted sound based on the time-series change of the sound pressure of the emitted sound detected by the microphone 47, and the calculated sound pressure and the set sound at the predetermined frequency. Since the quality of the molten metal filling state is determined by comparing the pressure, it is possible to perform the quality determination by removing noise caused by the sound having a frequency characteristic different from that of the injection sound, and the accuracy of the quality determination is improved. In addition, since the sound in the audible range is targeted, it is possible to use the knowledge of the skilled person in setting the set sound pressure and the like.

  The control device 5 calculates the sound pressure for each of a plurality of frequencies in the audible range of the emitted sound, and averages the sound pressure in a predetermined frequency range (for example, 900 to 1050 Hz) among the calculated sound pressures for each of the plurality of frequencies. Since the average value of the sound pressure in a predetermined frequency range is calculated, and the calculated average value is compared with the set sound pressure to determine the quality of the molten metal filling, the error generated for each frequency is averaged. Judgment accuracy is improved.

(Fourth embodiment)
The mechanical configuration of the molten metal filling state pass / fail determination apparatus according to the fourth embodiment of the present invention is the same as that of the first embodiment. That is, the molten metal filling state pass / fail determination apparatus according to the fourth embodiment is configured to include the control device 5 and the microphone 47 provided in the die casting machine 1 as shown in FIG. Also in the fourth embodiment, the die casting machine 1 performs the same molding cycle and injection process as those of the first embodiment described with reference to FIG.

  However, in the fourth embodiment, the control device 5 executes a quality determination process different from the quality determination process of the first embodiment described with reference to FIG. In the fourth embodiment, the control device 5 performs pass / fail determination based on the sound pressure for each frequency, as in the third embodiment. However, while the third embodiment calculates and determines the average, the fourth embodiment does not calculate the average and compares the sound pressure for each frequency with the set sound pressure to determine pass / fail. I do.

  FIG. 13 is a flowchart showing the procedure of the pass / fail determination process executed by the control device 5 to realize the pass / fail determination for comparing the sound pressure for each frequency as described above with the set sound pressure. For example, this process is performed in real time in parallel with the injection control of FIG. 2 in each molding cycle.

  Steps S41 to S45 are the same as steps S31 to S35 of FIG. Therefore, in steps S41 to S45, a predetermined set time To (for example, 0.01 seconds) elapses from the time when the sound is generated (when the absolute value of the instantaneous sound pressure exceeds the sound generation determination threshold value Pt). The instantaneous sound pressure is measured, and the measured value is subjected to Fourier transform to calculate the detected sound pressure for each frequency. Note that, as in the third embodiment, the detected sound pressure may be a Fourier-transformed value, effective sound pressure, sound pressure level, or the like.

  In step S46, it is determined for each frequency whether the detected sound pressure exceeds the set sound pressure. Note that the frequency for performing the comparison determination may be appropriately selected. For example, as shown in FIG. 11, in a predetermined frequency range (for example, 900 to 1050 Hz) in which the difference in sound pressure between the good product casting and the defective product casting becomes large, comparison judgment is made for all frequencies (in increments of Δf). Alternatively, some frequencies may be extracted from the above predetermined frequency range for comparison and determination. Without being restricted by the above-mentioned predetermined frequency range, some frequencies may be appropriately extracted from the range of 0/1 / (2Δt) to make a comparative determination. A comparison may be made by extracting the frequency. For example, the frequency range (20 to 5000 Hz) in which the sound pressure during defective casting tends to be higher than the sound pressure during good casting, and the sound pressure during good casting becomes higher than the sound pressure during defective casting. Some frequencies may be extracted from the trending frequency range (5000 to 20000 Hz) for comparison and determination (however, in this case, the sound pressure during good casting is higher than the sound pressure during defective casting). In the tendency frequency range (5000 to 20000 Hz), it is determined as abnormal when the detected sound pressure does not exceed the set sound pressure.)

  The set sound pressure may be set in common for all frequencies, or may be set for each frequency. The set sound pressure is set to 60 dB, for example, based on the experimental result of FIG.

  In step S47, it is determined whether or not the number of frequencies at which the detected sound pressure exceeds the set sound pressure exceeds a predetermined set number. If it is determined that the number has been exceeded, step S48 is executed, and then the process ends. If it is determined that it has not exceeded, step S48 is skipped and the process is terminated. Step S48 is the same process as step S28 of FIG.

  It should be noted that the number of settings to be compared with the number of frequencies at which the emission sound generation determination threshold, the set sound pressure, the set time, the frequency to be compared, and the detected sound pressure exceeds the set sound pressure are the die casting machine 1 (determination device 50) It may be set by the manufacturer of the machine, or may be set by the user of the die casting machine 1.

  According to the above 4th Embodiment, there exists an effect similar to 1st Embodiment. That is, it is possible to determine the quality of the molten metal filling state by numerically grasping the difference in the injection sound that only a skilled person can grasp the difference between normal and abnormal. In addition, the same effects as those of the third embodiment are obtained. That is, the sound pressure at a predetermined frequency is compared with the set sound pressure to determine the quality of the molten metal filling state. Therefore, it is possible to determine the quality by removing noise caused by a sound with a large sound pressure other than the emitted sound. This improves the accuracy of pass / fail judgment. Since the sound in the audible range is targeted, it is possible to use the knowledge of the skilled person in setting the set sound pressure and the like.

  The control device 5 calculates the sound pressure for each of the plurality of frequencies in the audible range of the emitted sound, compares the calculated sound pressure with the set sound pressure for each of the plurality of frequencies, and the calculated sound pressure sets the set sound pressure. Since it is determined that an abnormality has occurred when the number of frequencies that exceed the specified number, even if an erroneous determination due to an error or the like occurs at a specific frequency, the erroneous determination is the final pass / fail determination. Is reduced, and the accuracy of final pass / fail judgment is improved.

  Furthermore, if the set sound pressure is set for each frequency, the determination for each frequency can be performed more accurately, and the accuracy of the final pass / fail determination is further improved. For example, in FIG. 11 (a), there is a tendency to peak at a specific frequency (near 970 Hz). Become accurate.

(Fifth embodiment)
The mechanical configuration of the molten metal filling state pass / fail determination apparatus according to the fifth embodiment of the present invention is the same as that of the first embodiment. That is, the molten metal filling state pass / fail judgment device according to the fifth embodiment is configured to include the control device 5 and the microphone 47 provided in the die casting machine 1 as shown in FIG. Also in the fifth embodiment, the die casting machine 1 performs the same molding cycle and injection process as those of the first embodiment described with reference to FIG.

  In the fifth embodiment, the control device 5 performs pass / fail determination based on the sound pressure for each frequency, as in the third and fourth embodiments. However, in the fifth embodiment, the control device 5 executes a quality determination process different from the quality determination process of the third and fourth embodiments described with reference to FIGS. 12 and 13.

  In the third and fourth embodiments, when the chill vent 104 is closed, the emitted sound becomes louder in a predetermined frequency range (for example, 0 to 5000 Hz), so the sound pressure in that frequency range exceeds the set sound pressure. Was judged abnormal. In addition, when the chill vent 104 is closed, the emission sound is reduced in a frequency range of another frequency range (for example, 5000 to 20000 Hz), so that an abnormality occurs when the sound pressure in that frequency range is smaller than the set sound pressure. The method of judging was also mentioned.

  However, depending on the type of abnormality, the emission sound at the time of abnormality is smaller than that at the normal time in a predetermined frequency range (for example, 0 to 5000 Hz), and the emission at the time of abnormality in the other frequency range (for example, 5000 to 20000 Hz). It is also conceivable that the sound is louder than the normal sound. Therefore, in the fifth embodiment, the control device 5 executes a quality determination process that can detect various abnormalities.

  FIG. 14 shows one case at the time of non-defective casting and one case at the time of defective casting out of the frequency analysis results of 10 cases at the time of good casting and 10 cases at the time of defective casting shown in FIG. FIG.

15, of the frequency analysis results of FIG. 14, with an enlarged view of a predetermined frequency range (900~1050Hz), is a diagram showing an allowable range _{P R} as a reference for quality determination.

Tolerance _{P R} is defined by the upper limit value _{P LU} and the lower limit value _{P LD.} The upper limit value _PLU and the lower limit value _PLD are set for each frequency. The control unit 5, the sound pressure at each frequency of the injection sound, determines whether it is within the set tolerance P _R that for each frequency, if not within the allowable range P _R, abnormality occurs Is determined.

Upper limit value P _LU and the lower limit value P _LD tolerance P _R are included the sound pressure of the injection sound when good is cast, so that defective products do not contain sound pressure of the injection sound when it is cast Further, it may be set appropriately based on experiments or the like.

For example, when a non-defective product is cast, the sound pressure of the emitted sound for each frequency is set as the reference value P _PS of the allowable range P _RP , and a predetermined allowable width is set for the reference value P _PS , whereby the upper limit value is set. _PLU and lower limit value _PLD may be set. In this case, as the reference value _PPS , the sound pressure of the emitted sound for each frequency in one casting may be used, or the average of the sound pressure of the emitted sound for each frequency in a plurality of castings may be used. You may use the sound pressure of the injection sound for every frequency in casting. Further, the predetermined allowable range may be set separately for the upper limit side, the lower limit side, and each frequency, or may be set in common in any one of them. For the allowable width, for example, the standard deviation in multiple castings is calculated for the sound pressure of the emitted sound at each frequency when a non-defective product is cast, and the standard deviation or the standard deviation is multiplied by an appropriate correction factor. May be used.

Figure 16 is a sound pressure for each frequency, as described above, in order to achieve a quality decision for comparing the allowable range P _R, it is a flowchart illustrating a procedure of quality judgment processing by the control unit 5 executes. For example, this process is performed in real time in parallel with the injection control of FIG. 2 in each molding cycle.

  Steps S61 to S65 are the same as steps S31 to S35 in FIG. Therefore, in steps S61 to S65, a predetermined set time To (for example, 0.01 seconds) elapses from the time when the sound is generated (when the absolute value of the instantaneous sound pressure exceeds the sound generation determination threshold value Pt). The instantaneous sound pressure is measured, and the measured value is subjected to Fourier transform to calculate the detected sound pressure for each frequency. Note that, as in the third embodiment, the detected sound pressure may be a Fourier-transformed value, effective sound pressure, sound pressure level, or the like.

At step S66, the each frequency, and determines whether the detected sound pressure tolerance P _R in either. Note that the frequency for performing the comparison determination may be appropriately selected as in step S46 of the fourth embodiment. That is, the comparison determination may be performed in a predetermined frequency range, or the comparison determination may be performed without being restricted by the predetermined frequency range. Comparison determination may be performed for all frequencies (in increments of Δf), or some frequencies may be extracted for comparison determination.

  In addition, this embodiment has an advantage that an abnormality can be detected even if the correspondence between the type of abnormality and the frequency characteristic of the emitted sound is not known in advance by setting an allowable range based on the normal frequency characteristic. one of. In other words, one of the merits is that an unexpected abnormality can be detected. Therefore, it is effective to set the frequency for comparison and determination at a predetermined interval (for example, a constant interval) with respect to the entire audible range without being restricted by the predetermined frequency.

At step S67, the number of frequencies detected sound pressure becomes a permissible range P _R out is, determines whether or not exceeds a predetermined set number. If it is determined that the number has been exceeded, step S68 is executed, and then the process ends. If it is determined that it has not exceeded, step S68 is skipped and the process is terminated. Step S68 is the same process as step S28 of FIG.

Note that _(at least one of the tolerance upper limit value defining the P _R, the lower limit value, the reference value such as a parameter) injection sound occurrence determination threshold time setting, allowable range P _R, the frequency to be compared, the detected sound pressure The set number to be compared with the number of frequencies when the value is out of the allowable range may be set by the manufacturer of the die casting machine 1 (determination device 50) or set by the user of the die casting machine 1. Also good.

  According to the above 5th Embodiment, there exists an effect similar to 1st Embodiment. That is, it is possible to determine the quality of the molten metal filling state by numerically grasping the difference in the injection sound that only a skilled person can grasp the difference between normal and abnormal. In addition, the same effects as those of the third and fourth embodiments are achieved. That is, the sound pressure at a predetermined frequency is compared with the set sound pressure to determine the quality of the molten metal filling state. Therefore, it is possible to determine the quality by removing noise caused by a sound with a large sound pressure other than the emitted sound. This improves the accuracy of pass / fail judgment. Since the sound in the audible range is targeted, it is possible to use the knowledge of the skilled person in setting the set sound pressure and the like.

  Further, in the present embodiment, since the allowable range is set based on the normal frequency characteristics, the abnormality can be detected even if the correspondence between the type of abnormality and the frequency characteristic of the emitted sound is not known in advance. In other words, an unexpected abnormality can be detected.

  In the first to fifth embodiments described above, the determination device 50 is an example of the molten metal filling state pass / fail determination device of the present invention, the microphone 47 is an example of the detector of the present invention, and the control device 5 is It is an example of the quality determination part of this invention, an emitted sound generation | occurrence | production determination part, and a frequency analysis part.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The detector is not limited to a microphone as long as it can directly or indirectly detect the sound pressure of the emitted sound. For example, the sound is vibration of air, and the vibration is generated by the vibration of an object serving as a sound source. On the other hand, the sound source of the emitted sound is at least one of a mold and a molten metal. Thus, it is possible to indirectly detect the emission sound. Moreover, the arrangement position of the detector is not limited to the vicinity of the mold chill vent. For example, even if it is arranged near the injection sleeve (on the back side of the die mounting surface of the die plate), the injection sound can be detected via the injection sleeve.

  There are various indicators for sound pressure, such as instantaneous sound pressure, effective sound pressure, sound pressure level, etc., and any of these indicators may be used to determine pass / fail. For example, in the first embodiment, the case where the determination is made based on the instantaneous sound pressure is exemplified, but it may be determined whether or not the effective sound pressure or the sound pressure level exceeds the set sound pressure at the set time To. However, in this case, the time interval for calculating the effective sound pressure and the sound pressure level needs to be equal to or shorter than the set time To.

  The pass / fail judgment based on the comparison between the detected sound pressure of the emitted sound and the set sound pressure is such that the detected sound pressure of the emitted sound exceeds the set sound pressure as in the first, third and fourth embodiments. Sometimes determined as abnormal, as in the second and fifth embodiments, determined as abnormal when the sound pressure of the detected emission sound falls outside the allowable range (first setting as an upper limit value) It is not limited to one that determines an abnormality when either the sound pressure is exceeded or the value falls below the second set sound pressure as the lower limit value. When an abnormality occurs, the sound that is emitted has a lower sound pressure than the normal sound, or when an abnormality occurs, the sound that is emitted has a higher sound pressure than the normal sound. When the comparison is made at such a frequency that the sound pressure becomes small, it may be determined that the sound is abnormal when the sound pressure of the detected emission sound does not exceed the set sound pressure. For example, in FIG. 9, when the frequency is in the range of 5000 to 20000 Hz, the sound pressure is higher during non-defective casting than during defective casting. When the threshold value is not exceeded, it can be determined as abnormal.

  The first to fifth embodiments may be implemented in combination as appropriate. For example, the control device 5 may execute two or more of the quality determination methods shown in FIG. 5 or FIG. 8, FIG. 12, FIG. In this case, the abnormality process may be performed when it is determined to be abnormal in one of the plurality of pass / fail determination methods, or the abnormality process is performed when it is determined to be more than a predetermined number of methods. May be.

  In the first embodiment, when the number of times that the detected sound pressure exceeds the set sound pressure exceeds the predetermined number of times, it is determined that there is an abnormality. Good. That is, if the detected sound pressure exceeds the set sound pressure even once, it may be determined as abnormal. In this case, since it is only necessary to determine whether or not the detected sound pressure exceeds the set sound pressure, it is not necessary to specify the amplitude of the sound pressure, and the configuration is simple because it is sufficient to sequentially compare each sampling. become. In the first embodiment, an average value such as a peak value may be calculated as in the second embodiment, and it may be determined whether or not the average value exceeds a set sound pressure.

  In the second embodiment, when the average of the peak values is outside the allowable range, it is determined as abnormal. However, as in the first embodiment, it is determined whether each peak value is within the allowable range, and the allowable range is reached. You may determine with abnormality, when the number which became outside exceeds a predetermined setting number. It may be determined whether or not each peak value is within an allowable range, and it may be determined that there is an abnormality when there is at least one out of the allowable range.

  In the third to fifth embodiments, the detected sound pressure and the set sound pressure are compared for a plurality of frequencies by comparison of average values or individual comparisons. May be determined. In the fifth embodiment, as in the fourth embodiment, it is determined whether or not the frequency is within the allowable range for each frequency, and it is determined that there is an abnormality when the number outside the allowable range exceeds a predetermined number. Similarly to the third embodiment, an average value may be calculated for a predetermined frequency range, and an abnormality may be determined when the average value is outside the allowable range.

  The method of performing final pass / fail determination based on a plurality of determinations is not limited to those shown in the first to fifth embodiments. For example, in the first embodiment, it is determined whether or not the detected sound pressure exceeds the set sound pressure at a plurality of sampling times set at constant time increments, and the number exceeds the predetermined set number of times. Sometimes, it may be finally determined as abnormal.

  Processing performed in real time in parallel with the detection of the sound pressure by the microphone shown in the first to fifth embodiments (for example, steps S22 to S26 in FIG. 5, steps S51 to S54 in FIG. 8, and FIG. 12) Steps S32 to S34, Steps S42 to 44 in FIG. 13, and Steps S61 to S64 in FIG. 16 sequentially record the sound pressure data detected by the microphone in the RAM 31 and the like, and the data for a predetermined period required for pass / fail judgment. May be performed after the data has been accumulated. In this case, since the sampling period for sampling the sound pressure detected by the microphone can be separated from the time required for each process, the sound pressure can be detected with a sampling period shorter than the time required for each process. In other words, highly accurate determination can be made without shortening the time required for each process. Therefore, determination accuracy can be improved while reducing the burden on hardware.

  The detection of the emission sound is not limited to the detection based on whether or not the detected sound pressure exceeds the emission sound generation determination threshold. For example, if the difference between the generation timing of the injection sound specified from the position of the injection plunger and the actual generation timing of the injection sound is shorter than the set time To, the generation timing of the injection sound is determined from the position of the injection plunger. The sound after the specified occurrence timing may be used as the emission sound.

  When the generation of the emission sound is specified by comparing the sound pressure with the emission sound generation determination threshold, the sound pressure for each frequency is calculated and compared for each one or a plurality of frequencies, as in the case of pass / fail determination. The average of the frequency ranges may be compared.

The figure which shows the structure of the die-casting machine provided with the molten metal filling state quality determination apparatus which concerns on the 1st Embodiment of this invention. The flowchart which shows the procedure of the injection control which the control apparatus of the die-casting machine of FIG. 1 performs. The figure which shows the time-sequential change of the injection sound when a good article is cast. The figure which shows the time-sequential change of the injection sound when inferior goods are cast. The flowchart which shows the procedure of the quality determination process which the molten metal state quality determination apparatus of FIG. 1 performs. The figure which shows the time-sequential change of the injection sound when a good article is cast with an allowable range. The figure which shows the time-sequential change of the injection sound when inferior goods are cast with an allowable range. The flowchart which shows the procedure of the quality determination process which the molten state quality determination apparatus which concerns on the 2nd Embodiment of this invention performs. The figure which shows the frequency analysis result in the audible range of an emitted sound. The figure which shows the frequency analysis result in the frequency range narrower than FIG. The figure which shows the frequency analysis result in the frequency range narrower than FIG. The flowchart which shows the procedure of the quality determination process which the molten metal state quality determination apparatus which concerns on the 3rd Embodiment of this invention performs. The flowchart which shows the procedure of the quality determination process which the molten metal state quality determination apparatus which concerns on the 4th Embodiment of this invention performs. The figure which shows the frequency analysis result of an injection sound. The figure which shows the frequency analysis result in a frequency range narrower than FIG. 14 with a tolerance | permissible_range. The flowchart which shows the procedure of the quality determination process which the molten metal state quality determination apparatus which concerns on the 5th Embodiment of this invention performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Die-casting machine, 5 ... Control apparatus (quality determination part), 47 ... Microphone, 50 ... Determination apparatus (molten metal filling state quality determination apparatus), 100A ... Fixed mold, 100B ... Moving mold, Ca ... Cavity.

Claims (12)

A detector capable of detecting the sound pressure of the injection sound generated when the molten metal is filled into the mold cavity;
A pass / fail judgment unit that judges the quality of the molten state by comparing the sound pressure of the injection sound detected by the detector with a predetermined set sound pressure;
An apparatus for determining whether or not a molten metal is filled in a die-casting machine comprising: An emission sound generation determination unit for determining whether the sound pressure detected by the detector exceeds a predetermined emission sound generation determination threshold;
The pass / fail determination unit is configured to detect the sound detected by the detector during a predetermined set time after the sound generation determination unit determines that the sound pressure detected by the detector has exceeded the emission sound generation determination threshold. The molten metal filling state pass / fail determination apparatus according to claim 1, wherein a pressure is set as a sound pressure of the injection sound, and the sound pressure is compared with the set sound pressure to determine whether the molten metal is filled. The apparatus according to claim 2, wherein the predetermined set time is 0.01 seconds. The quality determination unit determines that an abnormality has occurred in a molten metal filling state when the number of times the sound pressure of the emitted sound detected by the detector exceeds the set sound pressure exceeds a predetermined set number. The molten metal filling state quality determination apparatus for the die casting machine according to any one of 1 to 3. As the set sound pressure, an upper limit value and a lower limit value of a predetermined allowable range are set,
The quality determination unit determines that an abnormality has occurred in a molten metal filling state when an average of sound pressure peak values detected by the detector is not within the allowable range. The molten metal filling state quality determination device for a die casting machine according to claim 1. A frequency analysis unit that calculates a sound pressure at a predetermined frequency in the audible range of the emitted sound based on a temporal change in the sound pressure of the emitted sound detected by the detector;
The quality determination unit determines the quality of the molten state by comparing the sound pressure at the predetermined frequency calculated by the frequency analysis unit with the set sound pressure. The molten metal filling state pass / fail judgment device of the described die casting machine. The frequency analysis unit calculates a sound pressure for each of a plurality of frequencies in an audible range of the emitted sound, and averages a sound pressure in a predetermined frequency range among the calculated sound pressures for each of the plurality of frequencies. Calculate the average value of the sound pressure in the frequency range,
The said quality determination part determines the quality of the filling state of a molten metal by comparing the said average value calculated by the said frequency analysis part, and the said set sound pressure, The molten state filling state quality determination apparatus of the die-casting machine of Claim 6 . The frequency analysis unit calculates a sound pressure for each of a plurality of frequencies in the audible range of the emitted sound,
The pass / fail judgment unit compares the sound pressure calculated by the frequency analysis unit with the set sound pressure for each of the plurality of frequencies to determine whether there is an abnormality for each frequency, and the number of frequencies determined to be abnormal The apparatus for determining whether or not the molten metal filling state is good for the die casting machine according to claim 6, wherein when the number exceeds a predetermined number, an abnormality has occurred in the molten metal filling state. The pass / fail judgment unit compares the sound pressure calculated by the frequency analysis unit with the set sound pressure in a frequency range of 20 to 5000 Hz, and the sound pressure calculated by the frequency analysis unit calculates the set sound pressure. It is determined that an abnormality has occurred when the temperature exceeds the range. As the set sound pressure, an upper limit value and a lower limit value of a predetermined allowable range are set,
The molten metal for a die casting machine according to claim 6, wherein the quality determination unit determines that an abnormality has occurred in a molten state when the sound pressure at the predetermined frequency calculated by the frequency analysis unit is not within the allowable range. Filling state pass / fail judgment device. The molten metal filling state pass / fail determination apparatus for a die casting machine according to any one of claims 1 to 10, further comprising a notification unit that notifies that an abnormality has been determined by the pass / fail determination unit.   The detector detects the sound pressure of the emitted sound that is generated when the molten metal is filled into the mold cavity, and compares the detected sound pressure with a preset sound pressure to determine whether the molten metal is in a good state. To determine whether or not the molten state of the die casting machine is good.