Molding machine control system, molding machine control method, and program

Abstract

A molding machine control system, a molding machine control method, and a program are provided that can reduce the occurrence of molding defects. [Solution] The resin property identifying device 6 has an AE wave information acquiring unit 611 that acquires AE wave information, a feature calculating unit 613 that calculates feature quantities based on the AE wave information, and a fluidity index identifying unit 617 that identifies the MFI based on the correlation between the injection speed and the feature quantities when the injection speed is changed when extruding the molten resin. The molding machine control device 1 has an injection speed setting unit that sets the injection speed of the molding machine based on the target viscosity and MFI of the molten resin discharged from the discharge nozzle of the molding machine, and an injection control unit that controls the injection mechanism of the molding machine to inject the molten resin at the set injection speed.

Description

[Technical Field]

[0001] The present invention relates to a molding machine control system, a molding machine control method, and a program. [Background technology]

[0002] An injection molding machine has been proposed that includes a cylinder for containing molten resin, a discharge nozzle, and a piston for discharging the molten resin from the discharge nozzle, and that calculates a target pressure for the molten resin in the cylinder based on the indicated flow rate of the molten resin discharged from the discharge nozzle, the temperature of the molten resin, and the theoretical value of the plastic viscosity of the molten resin estimated from the temperature of the molten resin, and controls the pressure of the molten resin in the cylinder to be the target pressure (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-154934 Summary of the Invention [Problem to be solved by the invention]

[0004] In injection molding machines such as those described in Patent Document 1, it has been studied to reduce the occurrence of molding defects by controlling the injection speed of the melt so that the actual plastic viscosity of the injected molten resin is maintained at a target plastic viscosity that corresponds to the nozzle diameter of the discharge nozzle, the shape and dimensions of the object to be molded, etc.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a molding machine control system, a molding machine control method, and a program that can reduce the occurrence of molding defects. [Means for solving the problem]

[0006] In order to achieve the above object, the molding machine control system according to the present invention comprises: A molding machine control system for controlling a molding machine including a cylinder that accommodates molten resin, a discharge nozzle that communicates with the cylinder, and an injection mechanism that pressurizes the molten resin in the cylinder toward the discharge nozzle, thereby injecting the molten resin from the discharge nozzle, an acoustic emission wave information acquiring unit that acquires acoustic emission wave information indicating the amplitude of an acoustic emission wave detected by an acoustic emission wave sensor that measures an acoustic emission wave generated when the molten resin is pressurized; a feature amount calculation unit that calculates a feature amount of the acoustic emission wave based on the acoustic emission wave information; a fluidity index specifying unit that specifies a fluidity index indicating the fluidity of the molten resin based on a correlation between the injection speed and the feature amount when the injection speed is changed when the molten resin is injected; a parameter setting unit that sets an injection speed when the molten resin in the cylinder is injected by the injection mechanism based on a target viscosity of the molten resin discharged from the discharge nozzle and the fluidity index; an injection control unit that controls the injection mechanism so as to extrude the molten resin in the cylinder at the set injection speed. [Effects of the Invention]

[0007] According to the present invention, the fluidity index specifying unit specifies a fluidity index that indicates the fluidity of the molten resin based on the correlation between the injection speed and the feature amount when the injection speed of the molten resin is changed. Then, the injection speed setting unit sets the injection speed when the molten resin in the cylinder is injected by the injection mechanism of the molding machine based on the target viscosity of the molten resin discharged from the discharge nozzle of the molding machine and the fluidity index. This makes it possible to set the injection speed when the molten resin is injected so that the viscosity of the molten resin becomes the target viscosity suitable for the shape, dimensions, etc. of the molding object, thereby reducing the occurrence of molding defects. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a configuration of a molding machine system according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing a configuration of a molding machine control device according to an embodiment; [Figure 3] FIG. 1 is a diagram showing the correlation between the viscosity of a molten resin and the injection speed. [Figure 4] 1 is a block diagram showing the configuration of a resin property specifying device according to an embodiment; [Figure 5] FIG. 1A is a diagram showing an example of an AE wave detected by an AE wave sensor according to an embodiment, and FIG. 1B is a diagram showing another example of an AE wave detected by an AE wave sensor according to an embodiment. [Figure 6] FIG. 10 is a diagram showing the correlation between the intensity of the AE wave detected by the AE wave sensor and the injection speed. [Figure 7] 4 is a flowchart showing an example of the flow of an injection control process executed by a molding machine control device according to an embodiment. [Figure 8] 10 is a flowchart showing an example of the flow of a resin property identification process executed by a resin property identification device according to an embodiment. [Figure 9] (A) is a diagram showing an example of an AE wave detected by an AE wave sensor, and (B) is a diagram showing the relationship between the intensity of the AE wave detected by the AE sensor and the proportion of material with an MFI of 1.1 contained in the molten resin. [Figure 10] 1A is a graph showing the relationship between the intensity of the AE wave detected by the AE sensor and the MFI of the molten resin, and FIG. 1B is a graph showing the relationship between the intensity of the AE wave detected by the AE sensor and the content ratio of PE and PP in the molten resin. [Figure 11] FIG. 10 is a diagram showing the correlation between the rise time of the AE wave and the MFI. DETAILED DESCRIPTION OF THE INVENTION

[0009] A molding machine control system according to an embodiment of the present invention will be described below with reference to the drawings. The molding machine control system according to this embodiment controls a molding machine that includes a cylinder that contains molten resin, a discharge nozzle that communicates with the cylinder, and an injection mechanism that pressurizes the molten resin in the cylinder toward the discharge nozzle, thereby discharging the molten resin from the discharge nozzle. This molding machine control system includes an acoustic emission wave information acquisition unit that acquires acoustic emission wave information indicating the amplitude of acoustic emission waves detected by an acoustic emission wave sensor that measures acoustic emission waves generated when molten resin is pressurized; a feature calculation unit that calculates a feature of the acoustic emission wave based on the acoustic emission wave information; a fluidity index identification unit that identifies a fluidity index indicating the fluidity of the molten resin based on the correlation between the flow rate and the feature when the injection speed of the molten resin is changed; an injection speed setting unit that sets the injection speed when the molten resin in the cylinder is injected by the injection mechanism based on the target viscosity of the molten resin discharged from the discharge nozzle and the fluidity index; and an injection control unit that controls the injection mechanism to inject the molten resin in the cylinder at the set injection speed.

[0010] As shown in FIG. 1, the molding machine system according to this embodiment includes a molding machine 2, a mold 3, a molding machine control device 1 that controls the operation of the molding machine 2, and a resin property identification device 6. The molding machine 2 includes a cylinder 21 that accommodates molten resin, a discharge nozzle 22 that communicates with the cylinder 21, and an injection mechanism 23 that extrudes the molten resin from the discharge nozzle 22. The cylinder 21 is cylindrical and defines a molten resin conveying space 21a and a molten resin holding space 21b, separated by a check valve 236 (described below). A funnel-shaped hopper 24 that receives the resin is provided so as to communicate with the conveying space 21a in the cylinder 21. Band-shaped heaters 25A, 25B, and 25C are wound around the outer wall of the cylinder 21. The discharge nozzle 22 has a discharge hole 22a that communicates with the holding space 21b in the cylinder 21.

[0011] The injection mechanism 23 includes a screw 231 that transports resin introduced from the hopper 24 into the transport space 21a in the cylinder 21, a check valve 236 fixed to the tip of the screw 231, a rotational drive motor 235, an axial drive motor 232, and a driver 233. The rotational drive motor 235 is connected to the base end of the screw 231 and drives the screw 231 to rotate around a central axis J1 along its longitudinal direction. The axial drive motor 232 is connected to the screw 231 and the rotational drive motor 235 via a shaft 234 and drives the screw 231 and the rotational drive motor 235 together in the direction of the central axis J1 of the screw 231. The axial drive motor 232 is equipped with a rotary encoder (not shown) and outputs a rotational angle signal reflecting the rotational angle to the driver 233. The driver 233 supplies current to the rotational drive motor 235 or the axial drive motor 232 based on a control signal input from the molding machine control device 1, thereby rotating the screw 231 and driving the screw 231 and the rotational drive motor 235 in a direction along the central axis J1. Here, the check valve 236 connects the holding space 21b to the conveying space 21a when the screw 231 moves backward along the central axis J1 in a direction toward the axial drive motor 232. On the other hand, the check valve 236 is configured to block the communication between the holding space 21b and the conveying space 21a when the screw 231 moves forward along the central axis J1 in a direction away from the axial drive motor 232. When metering the molten resin, the axial drive motor 232 drives the screw 231 to move backward, while the rotation drive motor 235 drives the screw 231 to rotate, so that the resin poured into the conveying space 21a from the hopper 24 travels along the groove of the screw 231 and is conveyed to the tip of the cylinder 21. At this time, for example, pellet-like resin travels along the groove of the screw 231 and becomes molten due to shear heat caused by rotation and heat from heaters 25A, 25B, and 25C, and is conveyed toward the tip of the cylinder 21. The resin poured into the conveying space 21a passes through the check valve 25 and flows into the holding space 21b of the cylinder 21.On the other hand, when the axial drive motor 232 drives the screw 231 to move forward during injection of the molten resin, the check valve 236 closes, and the molten resin filled in the holding space 21b of the cylinder 21 is pressurized toward the discharge nozzle 22 by the check valve 236, forcing it toward the discharge nozzle 22. At this time, the driver 233 adjusts the movement speed of the check valve 25 so that the molten resin is pressurized and forced toward the discharge nozzle 22 at an injection speed indicated by a control signal, which will be described later. As a result, the molten resin filled in the holding space 21b of the cylinder 21 is discharged from the discharge hole 22a. Then, each time the driver 233 controls the axial drive motor 232 to inject the molten resin in the holding space 21b of the cylinder 21, it outputs an injection completion notification signal to the molding machine control device 1 to notify that injection of the molten resin has been completed.

[0012] Attached to the cylinder 21 and discharge nozzle 22 of the molding machine 2 are AE wave sensors 26A and 26B that detect acoustic emission waves (hereinafter referred to as "AE waves") generated inside the cylinder 21 and discharge nozzle 22. The AE wave sensors 26A and 26B each have, for example, a piezoelectric element, and periodically generate an AE wave signal indicative of the detected AE waves and output it to the resin property identifying device 6.

[0013] Furthermore, the cylinder 21 and the discharge nozzle 22 of the molding machine 2 are provided with temperature sensors 27A and 27B for detecting the temperatures of the molten resin present inside the cylinder 21 and the discharge nozzle 22. The temperature sensors 27A and 27B each have a temperature sensor, generate a temperature detection signal indicating the temperature detected by the temperature sensor, and output the signal to the molding machine control device 1.

[0014] The mold 3 has a filling area S3 formed therein into which the molten resin is to be filled, and an introduction hole 3a for introducing the molten resin into the filling area S3 is formed in part of the peripheral wall. The mold 3 is placed in a state in which the introduction hole 3a communicates with the discharge hole 22a of the discharge nozzle 22 of the molding machine 2 during injection molding.

[0015] The molding machine control device 1 is realized, for example, by including a programmable logic controller. As shown in FIG. 2, the device includes a processing unit 101, an input unit 105, interfaces 171, 172, and 173, and a communication interface 106. The processing unit 101 includes a central processing unit (CPU), a volatile memory such as a random access memory (RAM), and a nonvolatile memory such as a semiconductor memory. The nonvolatile memory stores programs for implementing various functions of the processing unit 101. The input unit 105 includes, for example, a key input device. When operated by a user of the molding machine 2, the input unit 105 outputs operation information indicating the operation to the processing unit 101. The interface 172 converts temperature detection signals input from the temperature sensors 27A and 27B into temperature information and transfers the temperature information to the processing unit 101. The interface 173 converts control information transferred from the processing unit 101 into a control signal and transfers the control signal to a driver 233 of the molding machine 2. Furthermore, when the above-mentioned injection completion notification signal is input from the driver 233, the interface 173 converts the input injection notification signal into injection completion notification information and transfers it to the processing unit 101. The communication interface 106 has, for example, a wireless module, and communicates with the resin property identifying device 6.

[0016] In the processing unit 101, the CPU loads programs stored in the nonvolatile memory into the volatile memory and executes them, thereby functioning as a temperature information acquisition unit 113, an instruction amount acquisition unit 114, an injection speed setting unit 115, an injection control unit 116, a fluidity index acquisition unit 117, a reception unit 118, a pre-injection speed setting unit 119, and a pre-injection information notification unit 120. The non-volatile memory also includes an AE wave information storage unit 131, a temperature information storage unit 132, an instruction amount storage unit 133, a feature amount storage unit 134, an injection speed storage unit 135, a fluidity index storage unit 136, and a pre-injection speed storage unit 137. The AE wave information storage unit 131 stores AE wave information indicating the amplitude of the AE waves measured by the AE wave sensors 26A, 26B in association with sensor identification information that identifies the AE wave sensors 26A, 26B that performed the measurement. The AE wave information storage unit 131 stores, in chronological order, AE wave information indicating the amplitude values ​​of AE waves generated when injection molding is performed in the molding machine 2, as shown in FIG. 3(A), for example.

[0017] Returning to FIG. 2, the temperature information storage unit 132 stores temperature information indicating the temperature of the molten resin measured by the temperature sensors 27A and 27B in association with sensor identification information that identifies the temperature sensors 27A and 27B that performed the measurement.

[0018] The instruction amount storage unit 133 stores instruction amount information indicating the target viscosity of the molten resin to be discharged from the discharge nozzle 22, which is set by the user. Here, the user determines the target viscosity of the molten resin based on the opening diameter of the discharge hole 22a of the discharge nozzle 22 and the shape, dimensions, etc. of the molding target, i.e., the shape, dimensions, etc. of the filling region S3 of the mold 3. The fluidity index storage unit 134 stores MFI information indicating the MFI (Melt Flow Index), which is a fluidity index of the molten resin identified by the resin property identification device 6.

[0019] The injection speed storage unit 135 stores information indicating the relationship between the injection speed at which the molten resin is injected, the viscosity of the molten resin when extruded at that injection speed, the temperature of the molten resin, and the melt flow index (MFI) of the molten resin. Here, the injection speed corresponds to the speed at which the check valve 25 is moved toward the discharge nozzle 22 during injection of the molten resin. The injection speed storage unit 135 may store correlation information indicating the correlation between the viscosity of the molten resin and the injection speed for each of a plurality of preset combinations of the temperature range and MFI of the molten resin, in association with the information indicating the combination of the temperature range and MFI of the molten resin. In fact, for molten resins with MFIs of 1.1 and 0.8, the correlation between the viscosity of the molten resin and the injection speed is as shown in FIG. 3, for example.

[0020] Returning to Figure 2, the pre-injection speed memory unit 137 stores pre-injection injection speed information indicating the injection speeds of multiple types of molten resin when pre-injection is performed in which molten resin is injected as a dummy at multiple different injection speeds before the molding machine 2 repeatedly injection molds a resin product.

[0021] The temperature information acquisition unit 113 acquires the aforementioned temperature information corresponding to each of the temperature sensors 27A and 27B, and stores the acquired temperature information in the temperature information storage unit 132 in association with sensor identification information that identifies the corresponding temperature sensors 27A and 27B. Here, the temperature information acquisition unit 113 acquires the temperature information corresponding to each of the temperature sensors 27A and 27B by transmitting a temperature request signal that requests the temperature sensors 27A and 27B to transmit temperature information. Alternatively, the temperature information acquisition unit 113 may acquire temperature information obtained by converting, by the interface 172, temperature detection signals that are voluntarily and periodically transmitted from each of the temperature sensors 27A and 27B.

[0022] The receiving unit 118 receives operations performed by the user on the input unit 105. Here, when the receiving unit 118 receives an instruction amount setting operation for instructing a target viscosity by the user, the receiving unit 118 generates instruction amount information indicating the target viscosity based on the operation content of the received instruction amount setting operation, and notifies the instruction amount acquiring unit 114. When the instruction amount acquiring unit 114 is notified of the instruction amount information from the receiving unit 118, it stores the notified instruction flow information in the instruction amount storage unit 133.

[0023] When the fluidity index acquisition unit 117 acquires the fluidity index notification information described below transmitted from the resin property identification device 6, it extracts the MFI information contained in the acquired fluidity index notification information and stores the extracted MFI information in the fluidity index memory unit 134.

[0024] The injection speed setting unit 115 sets the injection speed when the molten resin in the holding space 21b of the cylinder 21 is injected by the injection mechanism 23 based on the target viscosity of the molten resin, the temperature of the molten resin, and the MFI of the molten resin. Specifically, the injection speed setting unit 115 identifies the correlation information stored in the injection speed memory unit 135, which corresponds to the combination of the MFI indicated by the MFI information stored in the fluidity index memory unit 134 and the temperature range indicated by the temperature of the molten resin indicated by the temperature information memory unit 132. The injection speed setting unit 115 also calculates the injection speed of the molten resin from the identified correlation information and the viscosity indicated by the instruction amount information stored in the instruction amount memory unit 133. The injection speed setting unit 115 then notifies the injection control unit 116 of the injection speed information indicating the calculated injection speed.

[0025] When the injection control unit 116 is notified of the injection speed information from the injection speed setting unit 115, the injection control unit 116 generates control information for controlling the injection speed at which the molten resin in the holding space 21b of the cylinder 21 is forced toward the discharge nozzle 22 by the check valve 25 during injection molding by the molding machine 2 to be the injection speed indicated by the notified injection speed information. Then, the injection control unit 116 notifies the interface 173 of the generated control information, thereby outputting a control signal corresponding to the control information to the driver 233 of the injection mechanism 23 of the molding machine 2. Furthermore, when the injection control unit 116 is notified of injection speed information indicating the injection speed of the molten resin during the pre-injection from the pre-injection speed setting unit 119, the injection control unit 116 generates control information for controlling the injection speed of the molding machine 2 to be the injection speed indicated by the notified injection speed information, and notifies the interface 173. In this case, the injection control unit 116 notifies the pre-injection information notifying unit 120 of injection start notification information that notifies that injection molding will be started by the molding machine 2. Immediately after notifying the interface 173 of the control information generated based on the injection speed information notified from the pre-injection speed setting unit 119, the injection control unit 116 receives injection completion notification information obtained by converting the above-mentioned injection completion notification signal from the interface 173, and notifies the notified injection completion notification information to the pre-injection speed setting unit 119 and the pre-injection information notifying unit 120.

[0026] The pre-injection speed setting unit 119 selects one by one from the multiple types of injection speed information stored in the pre-injection speed memory unit 137 when performing pre-injection, which involves dummy injection of molten resin into the molding machine 2, and notifies the injection control unit 116 and the pre-injection information notification unit 120. Here, the pre-injection speed setting unit 119 selects another piece of injection speed information each time injection completion notification information is notified from the injection control unit 116, and repeats this process until all of the multiple types of injection speed information have been selected. Then, when the pre-injection speed setting unit 119 has completed notifying the injection control unit 116 and the pre-injection information notification unit 120 of all of the injection speed information stored in the pre-injection speed memory unit 137, the pre-injection speed setting unit 119 notifies the pre-injection end notification information to the pre-injection information notification unit 120.

[0027] When the pre-injection information notification unit 120 is notified of the injection speed information from the pre-injection speed setting unit 119, it generates pre-injection information including the notified injection speed information and injection identification information that identifies each pre-injection, and transmits it to the resin property identifying device 6. Then, when the pre-injection information notification unit 120 is notified of the pre-injection end notification information together with the injection speed information from the pre-injection speed setting unit 119, it generates pre-injection information including the notified injection speed information, the pre-injection end notification information, and the injection identification information, and transmits the generated pre-injection information to the resin property identifying device 6 via the communication interface 106.

[0028] Returning to FIG. 1 , the resin property identifying device 6 is realized by, for example, a personal computer, and as shown in FIG. 4 , is equipped with a processing unit 601, a display unit 604, an input unit 605, an interface 671, and a communication interface 606. The processing unit 601 has a CPU, a volatile memory such as RAM, and a non-volatile memory such as a semiconductor memory. The non-volatile memory stores programs for implementing various functions of the processing unit 601. The display unit 604 has a display device such as a liquid crystal display. The interface 671 converts the AE wave signals input from the AE wave sensors 26A and 26B into AE wave information and transfers it to the processing unit 601. The communication interface 606 has, for example, a wireless module and communicates with the molding machine control device 1.

[0029] In the processing unit 601, the CPU loads programs stored in the nonvolatile memory into the volatile memory and executes them, thereby functioning as an AE wave information acquisition unit 611, a feature amount calculation unit 613, a correlation information generation unit 614, an MFI identification unit 617, an MFI notification unit 618, and a pre-injection information acquisition unit 619. The non-volatile memory also includes an AE wave information storage unit 631, a feature amount calculation unit 632, a correlation information storage unit 633, a reference correlation information storage unit 634, and a pre-injection information storage unit 635. The AE wave information storage unit 631 stores AE wave information indicating the amplitude of AE waves measured by the AE wave sensors 26A, 26B when resin is injected multiple times while the temperature of the resin in the cylinder 21 is changed in the molding machine 2, in association with injection identification information identifying each of the multiple injection processes, together with sensor identification information identifying the AE wave sensors 26A, 26B that performed the measurement. The AE wave information storage unit 631 stores, in chronological order, AE wave information indicating the amplitude values ​​of AE waves generated when injection molding is performed in the molding machine 2, as shown in FIG. 5(A), for example.

[0030] The feature amount storage unit 632 stores, in association with the injection identification information, feature amount information indicating feature amounts of the amplitude shape of the AE waves measured by the AE wave sensors 26A and 26B during at least one past injection molding operation stored in the AE wave information storage unit 131. Here, the feature amount may be the maximum amplitude Imax1, the maximum amplitude Imax2 of the first pulse train that occurs consecutively with an amplitude smaller than the amplitude of the maximum peak that occurs immediately after the maximum peak, or the maximum amplitude Imax3 of the second pulse train that occurs consecutively with an amplitude smaller than the first pulse train that occurs immediately after the first pulse train. Alternatively, the feature amount may be the average, maximum, minimum, or median of any of the maximum amplitudes Imax1, Imax2, and Imax3 of the AE waves measured during multiple past injection molding operations. Alternatively, the feature amount may be the ratio Imax1 / Imax2 of the maximum amplitude Imax1 to the maximum amplitude Imax2.

[0031] The pre-injection information storage unit 635 stores injection speed information indicating the multiple types of injection speeds employed in the pre-injection described above in association with the injection identification information.

[0032] The correlation information storage unit 633 stores correlation information indicating the correlation between the AE wave feature quantity and the injection speed for each of multiple preset resin types. Here, the correlation information indicates the coefficient values ​​of an exponential function obtained by approximating the AE wave feature quantity and the injection speed of the molten resin using an exponential approximation function. The reference correlation information storage unit 634 stores reference correlation information indicating a reference range of coefficient values ​​of the approximation function indicating the correlation between the AE wave feature quantity and the injection speed for each of multiple preset reference resin types, in association with MFI information indicating the MFI of the resin. Here, if the AE wave feature quantity is, for example, the maximum amplitude Imax1 of the waveform peak, the relationship between the feature quantity and the injection speed of resins with MFIs of "1.1" and "0.8" is represented by an approximation curve as shown by the dashed line in FIG. 6.

[0033] 4, when the AE wave information acquisition unit 611 acquires the above-mentioned AE wave information corresponding to each of the AE wave sensors 26A, 26B transferred from the interface 671, the AE wave information acquisition unit 611 associates the acquired AE wave information with sensor identification information that identifies the corresponding AE wave sensors 26A, 26B and stores the associated information in chronological order in the AE wave information storage unit 131. Here, the AE wave information acquisition unit 611 stores the AE wave information obtained when resin is injected multiple times while the injection speed is changed in the molding machine 2 in the AE wave information storage unit 631 in association with the injection identification information and sensor identification information stored in the pre-injection information storage unit 635.

[0034] The feature calculation unit 613 calculates the aforementioned feature indicating the characteristics of the detected AE wave based on the AE wave information stored in the AE wave information storage unit 631, and stores the calculated feature in the feature storage unit 632 in correspondence with the aforementioned emission identification information.

[0035] When the pre-injection information acquisition unit 619 acquires the pre-injection information transmitted from the molding machine control device 1, it extracts the injection speed information and the injection identification information included in the acquired pre-injection information, associates these pieces of extracted information with each other, and stores them in the pre-injection information storage unit 635. Furthermore, when the pre-injection information includes the pre-injection end notification information described above, the pre-injection information acquisition unit 619 notifies the correlation information generation unit 614 and the fluidity index identification unit 617 of the pre-injection end notification information.

[0036] When the pre-injection end notification information is notified from the pre-injection information acquisition unit 619, the correlation information generation unit 614 calculates at least one coefficient value of an approximation equation obtained by approximating, using a preset exponential approximation equation, the feature amount of the AE wave stored in the feature amount storage unit 632 and the injection speed information associated with the same injection identification information as the injection identification information corresponding to the AE wave information used to calculate the feature amount, stored in the pre-injection information storage unit 635. Then, the correlation information generation unit 614 stores correlation information indicating at least one coefficient value of the calculated approximation equation in the correlation information storage unit 633.

[0037] When the pre-injection end notification information is notified from the pre-injection information acquisition unit 619, the fluidity index identification unit 617 refers to the reference correlation information stored in the reference correlation information storage unit 634, and identifies MFI information corresponding to the reference range of coefficient values ​​to which at least one coefficient value indicated by the correlation information stored in the correlation information storage unit 632 belongs. Then, the fluidity index identification unit 617 notifies the fluidity index notification unit 618 of the identified MFI information. The fluidity index notification unit 618 generates fluidity index notification information including the MFI information notified from the fluidity index identification unit 617, and transmits the information to the molding machine control device 1 via the communication interface 606.

[0038] Next, a molding machine control process executed by the molding machine control device 1 according to this embodiment will be described with reference to Fig. 7. This molding machine control process is initiated when the user performs the aforementioned flow rate instruction operation to start an injection molding process using the molding machine 2 after power is applied to the molding machine control device 1. The molding machine control process shown in Fig. 5 illustrates a case in which the same resin product is repeatedly produced by using the molding machine 2 to inject molten resin into the mold 3 at the same flow rate. When the molding machine control process is initiated, the user first performs the aforementioned flow rate instruction operation, and then, before producing a resin product, performs pre-injection, in which the molding machine 2 injects molten resin as a dummy multiple times at different injection speeds, and then repeatedly injection-moldes the same resin product using the molding machine 2. Each time the AE wave information acquisition unit 111 periodically acquires the aforementioned AE wave information corresponding to each of the AE wave sensors 26A, 26B, it stores the acquired AE wave information in chronological order in the AE wave information storage unit 131 in association with sensor identification information and emission identification information that identify the corresponding AE wave sensors 26A, 26B.

[0039] First, when the user performs the above-mentioned instruction amount setting operation, the reception unit 118 receives the instruction amount setting operation, and generates instruction amount information indicating the viscosity of the molten resin instructed by the user based on the operation content of the received instruction amount setting operation, and notifies the instruction amount acquisition unit 114. Then, the instruction amount acquisition unit 114 acquires the notified instruction amount information, and stores the acquired instruction amount information in the instruction amount storage unit 133 (step S101).

[0040] Next, the pre-injection speed setting unit 119 selects one of the multiple types of injection speed information stored in the pre-injection speed memory unit 137 when performing a pre-injection in which the molding machine 2 dummy injects molten resin (step S102), and notifies the injection control unit 116 and the pre-injection information notification unit 120 of the selected injection speed information. Subsequently, the injection control unit 116 generates control information for controlling the molding machine 2 so that the injection speed of the molding machine 2 becomes the injection speed indicated by the injection speed information notified from the pre-injection speed setting unit 119, and notifies the interface 173 of the control information. As a result, a control signal corresponding to the control information is output from the interface 173 to the driver 233 of the injection mechanism 23 of the molding machine 2 (step S103). Thereafter, when the injection control unit 116 is notified of the above-mentioned injection notification completion information (step S104), it notifies the notified injection notification completion information to the pre-injection speed setting unit 119 and the pre-injection information notification unit 120. Then, when the pre-injection information notification unit 120 is notified of the injection completion notification information, it generates pre-injection information including the injection speed information and injection identification information notified by the pre-injection speed setting unit 119 and transmits it to the resin property identifying device 6 (step S105). Next, the pre-injection speed setting unit 119 determines whether or not pre-injection is completed (step S106). Here, the pre-injection speed setting unit 119 determines that pre-injection is completed if notification of all injection speed information stored in the pre-injection speed storage unit 137 to the injection control unit 116 and the pre-injection information notification unit 120 has been completed. Here, if the pre-injection speed setting unit 119 determines that pre-injection is not yet completed (step S106: No), the processing of step S103 is executed again.

[0041] On the other hand, when the pre-injection speed setting unit 119 determines that the pre-injection is completed (step S106: Yes), it notifies the pre-injection end notification information to the pre-injection information notifying unit 120. Then, the pre-injection information notifying unit 120 generates pre-injection information including the notified injection speed information, pre-injection end notification information, and injection identification information, and transmits the generated pre-injection information to the resin property identifying device 6 via the communication interface 106 (step S107).

[0042] Next, when the fluidity index acquisition unit 117 acquires the fluidity index notification information transmitted from the resin property identification device 6, it extracts the MFI information contained in the acquired fluidity index notification information and stores the extracted MFI information in the fluidity index memory unit 134 (step S108).

[0043] Thereafter, the temperature information acquisition unit 113 determines whether an injection instruction event instructing to inject molten resin has occurred (step S109). This injection instruction event may occur, for example, when a user performs an operation via the input unit 105 to inject molten resin to mold a resin product, or at a preset time interval for automatically and repeatedly molding resin products. As long as the temperature information acquisition unit 113 determines that an injection instruction event has not yet occurred (step S109: No), the process of step S109 is repeatedly executed. On the other hand, when the temperature information acquisition unit 113 determines that an injection instruction event has occurred (step S109: Yes), the temperature information acquisition unit 113 acquires the above-mentioned temperature information corresponding to each of the temperature sensors 27A and 27B, and stores the acquired temperature information in the temperature information storage unit 132 in association with sensor identification information that identifies the corresponding temperature sensors 27A and 27B (step S110).

[0044] Next, the injection speed setting unit 115 identifies the above-mentioned correlation information stored in the injection speed memory unit 135, which corresponds to the combination of the MFI indicated by the MFI information stored in the fluidity index memory unit 134 and the temperature range indicated by the temperature of the molten resin indicated by the temperature information stored in the temperature information memory unit 132. The injection speed setting unit 115 also calculates the injection speed of the molten resin from the identified correlation information and the viscosity indicated by the instruction amount information stored in the instruction amount memory unit 133. Then, the injection speed setting unit 115 sets the injection speed of the molding machine 2 to the calculated injection speed (step S111), and notifies the injection control unit 116 of injection speed information indicating the set injection speed.

[0045] The injection control unit 116 generates control information for controlling the injection speed when injecting the molten resin in the holding space 21b of the cylinder 21 during injection molding by the molding machine 2 to the injection speed indicated by the notified injection speed information, and notifies the interface 173 of the generated control information. As a result, a control signal corresponding to the control information is output from the interface 173 to the driver 233 of the injection mechanism 23 of the molding machine 2 (step S112). Thereafter, the processing of step S109 is executed again.

[0046] Next, the resin property identification process executed by the resin property identifying device 6 according to this embodiment will be described with reference to Fig. 8. This resin property identification process is started, for example, after the power to the resin property identifying device 6 is turned on, when the pre-injection information described above is acquired from the molding machine control device 1. First, when the pre-injection information acquisition unit 619 acquires the pre-injection information transmitted from the molding machine control device 1, it associates the injection speed information and the injection identification information included in the acquired pre-injection information with each other and stores them in the pre-injection information storage unit 635 (step S301).

[0047] Next, the AE wave information acquisition unit 611 acquires AE wave information corresponding to each of the AE wave sensors 26A and 26B, and stores the acquired AE wave information in chronological order in the AE wave information storage unit 131 in association with sensor identification information that identifies the corresponding AE wave sensors 26A and 26B (step S302).

[0048] Next, the feature calculation unit 613 calculates the above-mentioned feature indicating the characteristics of the detected AE wave based on the AE wave information stored in the AE wave information storage unit 631, and stores the feature information indicating the calculated feature in the feature storage unit 632 in association with the emission identification information (step S303).

[0049] Thereafter, the pre-ejection information acquisition unit 619 determines whether the acquired pre-ejection information includes the pre-ejection end notification information (step S304). If the pre-ejection information acquisition unit 619 determines that the acquired pre-ejection information does not include the pre-ejection end notification information (step S304: No), the processing of step S301 is executed again. On the other hand, if the pre-ejection information acquisition unit 619 determines that the acquired pre-ejection information includes the pre-ejection end notification information (step S304: Yes), the pre-ejection information acquisition unit 619 notifies the correlation information generation unit 614 and the liquidity index identification unit 617 of the pre-ejection notification information.

[0050] Next, when the pre-injection end notification information is notified, the correlation information generation unit 614 generates correlation information indicating the correlation between the features of the AE wave stored in the feature memory unit 632 and the injection speed indicated by the injection speed information stored in the pre-injection information memory unit 635, and stores the correlation information in the correlation information memory unit 633 (step S305).

[0051] Next, when the pre-injection end notification information is notified from the pre-injection information acquisition unit 619, the fluidity index identification unit 617 refers to the reference correlation information stored in the reference correlation information storage unit 634, and identifies MFI information corresponding to the reference range of coefficient values ​​to which at least one coefficient value indicated by the correlation information stored in the correlation information storage unit 632 belongs (step S306). Here, the fluidity index identification unit 617 notifies the fluidity index notification unit 618 of the identified MFI information. Thereafter, the fluidity index notification unit 618 generates fluidity index notification information including the MFI information notified from the fluidity index identification unit 617, and transmits it to the molding machine control device 1 via the communication interface 606 (step S307).

[0052] As described above, according to this embodiment, the fluidity index identifying unit 617 of the resin property identifying device 6 identifies the MFI, which indicates the fluidity of the molten resin, based on the correlation between the injection speed and the feature amount when the injection speed of the molten resin is changed. Then, the injection speed setting unit 115 of the molding machine control device 1 sets the injection speed when the molten resin in the holding space 21b of the cylinder 21 is extruded by the injection mechanism 23 based on the target viscosity of the molten resin discharged from the discharge nozzle of the molding machine 2 and the MFI. This makes it possible to set the injection speed when the molten resin is injected so that the viscosity of the molten resin becomes the target viscosity suitable for the shape, dimensions, etc. of the object to be molded, thereby reducing the occurrence of molding defects.

[0053] In this embodiment, the resin property identification device 6 identifies the MFI of the molten resin from the maximum intensity of the AE waves, which are characteristic quantities of the AE waves generated when the molten resin is injected, and the injection speed of the molten resin. This makes it possible to recognize when the molten resin to be injected has been switched to a molten resin with a different MFI, based on whether or not there is a change in the identified MFI. Furthermore, based on whether or not there is a change in the MFI, for example, when the lot of the resin fed into the molding machine 2 is switched, it is possible to confirm a change in the so-called grade of the resin. Therefore, for example, it is possible to quantitatively determine whether a different type of resin has been mixed into the resin used for injection molding.

[0054] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, if the molten resin contains two types of resin, the resin property identification device 6 may be equipped with a resin proportion estimation unit that estimates the proportions of each of the two types of resin contained in the molten resin based on the characteristic quantities of the molten resin. In this case, the injection speed setting unit 115 of the molding machine control device 1 sets the injection speed of the molding machine 2 based on the target viscosity determined based on the estimated proportions of the two types of resin.

[0055] For a molten resin containing a resin with an MFI of 1.1 and another with an MFI of 0.8, the maximum amplitude Imax1 of the AE wave, as shown in Figure 9(A), is used as a feature. When four types of molten resin with different proportions of MFI resin of 1.1 are injected at the same injection speed, a correlation is obtained between the feature and the proportion of MFI resin of 1.1, as shown in Figure 9(B). Furthermore, for a resin whose main component is polypropylene (random polypropylene), it has been confirmed that the maximum amplitude of the AE wave varies depending on the MFI and the ratio of polyethylene to polypropylene in the random polypropylene, as shown in Figures 10(A) and 10(B). The resin proportion estimation unit estimates the resin proportion based on this correlation.

[0056] According to this configuration, when the molten resin contains two types of resin, the target viscosity can be determined based on the respective proportions of the two types of resin contained in the molten resin, so that the injection speed can be set to suit the shape, dimensions, etc. of the object to be molded. Therefore, the occurrence of molding defects can be reduced, especially when using a molten resin containing two types of resin.

[0057] Furthermore, this configuration allows for estimation of the proportions of two types of resin in a molten resin, which is expected to be useful for quality control of molten resin in actual resin molding processes, management of manufacturing processes, and process development. In particular, the ability to manage changes in the proportions of each resin in a molten resin in real time can improve product quality.

[0058] In the embodiment, the rise time of the AE wave as shown in Fig. 5(A) may be used as the feature amount. For multiple types of resins with different fluidities, a correlation between the rise time and the FI as shown in Fig. 11, for example, may be obtained. Therefore, the fluidity index specifying unit 617 may specify the MFI based on the rise time of the AE wave.

[0059] In an embodiment, the resin property identification device 6 may be provided with a resin viscosity estimation unit that estimates the viscosity of the molten resin from the characteristic amount of the AE wave generated when the molten resin is injected (e.g., the maximum intensity of the AE wave) based on correlation information between the characteristic amount of the AE wave generated when the molten resin is injected and the viscosity of the molten resin.

[0060] This configuration makes it possible to estimate changes in the molecular weight, chemical structure (branched structure in the chemical structure, cross-linked structure at terminals, etc.) and chemical composition (e.g., the proportion of polyethylene structure contained in random polypropylene or block polypropylene) of the polymers that make up the molten resin, which are factors that can affect changes in the viscosity of the molten resin. Furthermore, if the molten resin is a polymer whose main component is a polymer to which a different polymer has been added, it is possible to estimate the addition status of the different polymer (alloy product such as a polymer blend).

[0061] In an embodiment, the resin property identification device 6 may have the function of identifying the chemical structure (e.g., copolymer structure, branched structure, etc.) of polymer compounds in general, such as polymer resins and rubber, the physical structure (crosslinked structure, gelled structure, etc.), additives (crosslinking agents, stabilizers, etc.), or the presence of foreign matter (moisture, different materials, etc.) other than the substance that is the main component of the object, based on the feature quantities of the AE wave.

[0062] Furthermore, the various functions of the molding machine control device 1 and resin property identifying device 6 according to the present invention can be realized using a normal computer system, rather than a dedicated system. For example, a program for executing the above operations may be stored on a non-transitory recording medium (such as a CD-ROM (Compact Disc Read Only Memory)) that can be read by a computer system and distributed to a computer connected to a network, and the program may be installed in the computer system to configure the molding machine control device 1 and resin property identifying device 6 that execute the above processes.

[0063] The method of providing the program to the computer is arbitrary. For example, the program may be uploaded to a bulletin board system (BBS) on a communication line and distributed to the computer via the communication line. The computer then launches the program and executes it like any other application under the control of an operating system (OS). This allows the computer to function as the molding machine control device 1 and resin property identification device 6 that execute the above-mentioned processes.

[0064] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these. The present invention includes any combination of the embodiments and modifications, and any combination to which appropriate modifications have been made. [Industrial Applicability]

[0065] The present invention is suitable as a system for controlling an injection molding machine. [Explanation of symbols]

[0066] 1: molding machine control device, 2: molding machine, 3: mold, 3a: introduction hole, 21: cylinder, 21a: conveying space, 22: discharge nozzle, 22a: discharge hole, 23: injection mechanism, 24: hopper, 25A, 25B, 25C: heater, 26A, 26B: AE wave sensor, 27A, 27B: temperature sensor, 101, 601: processing unit, 105: input unit, 106, 306: communication interface, 113: temperature information acquisition unit, 114: instruction amount acquisition unit, 115: injection speed setting unit, 116: injection control unit, 117: fluidity index acquisition unit, 118: reception unit, 119: pre-injection speed setting unit, 120: pre-injection information notification unit, 132: temperature information storage unit, 133: instruction amount storage unit, 134: fluidity index storage unit, 135: injection speed storage unit, 137: pre-injection speed storage unit, 172, 173, 671: interface, 611: AE wave information acquisition unit, 613: feature amount calculation unit, 614: correlation information generation unit, 617: fluidity index identification unit, 618: fluidity index notification unit, 619: pre-injection information acquisition unit, 631: AE wave information storage unit, 632: feature amount storage unit, 633: correlation information storage unit, 634: reference correlation information storage unit, 635: pre-injection information storage unit

Claims

1. A molding machine control system for controlling a molding machine including a cylinder that accommodates molten resin, a discharge nozzle that communicates with the cylinder, and an injection mechanism that pressurizes the molten resin in the cylinder toward the discharge nozzle, thereby injecting the molten resin from the discharge nozzle, an acoustic emission wave information acquiring unit that acquires acoustic emission wave information indicating the amplitude of an acoustic emission wave detected by an acoustic emission wave sensor that measures an acoustic emission wave generated when the molten resin is pressurized; a feature amount calculation unit that calculates a feature amount of the acoustic emission wave based on the acoustic emission wave information; a fluidity index specifying unit that specifies a fluidity index indicating the fluidity of the molten resin based on a correlation between the injection speed and the feature amount when the injection speed is changed when the molten resin is injected; an injection speed setting unit that sets an injection speed when the molten resin in the cylinder is injected by the injection mechanism based on a target viscosity of the molten resin discharged from the discharge nozzle and the fluidity index; an injection control unit that controls the injection mechanism so as to extrude the molten resin in the cylinder at the set injection speed, Molding machine control system.

2. Further, a temperature information acquisition unit is provided for acquiring the temperature of the molten resin in the cylinder, the injection speed setting unit sets the injection speed based on the target viscosity, the fluidity index, and the temperature of the molten resin. The molding machine control system according to claim 1 .

3. the acoustic emission wave sensor is attached to at least the discharge nozzle and detects acoustic emission waves transmitted to the discharge nozzle; The molding machine control system according to claim 1 or 2.

4. When the molten resin contains two types of resin, a resin proportion estimation unit is further provided that estimates a proportion of each of the two types of resin contained in the molten resin based on the feature amount, the injection speed setting unit sets the injection speed based on the target viscosity determined based on the ratio. The molding machine control system according to claim 1 or 2.

5. A molding machine control method for controlling a molding machine including a cylinder that accommodates molten resin, a discharge nozzle that communicates with the cylinder, and an injection mechanism that applies pressure to the molten resin in the cylinder toward the discharge nozzle, thereby discharging the molten resin from the discharge nozzle, comprising: acquiring acoustic emission wave information indicating the magnitude of the amplitude of an acoustic emission wave detected by an acoustic emission wave sensor that measures an acoustic emission wave generated when the molten resin is pressurized; calculating a feature amount of the acoustic emission wave based on the acoustic emission wave information; identifying a fluidity index indicating the fluidity of the molten resin based on a correlation between the injection speed and the feature amount when the injection speed is changed when the molten resin is injected; setting an injection speed when the molten resin in the cylinder is injected by the injection mechanism based on a target viscosity of the molten resin discharged from the discharge nozzle and the fluidity index; and controlling the injection mechanism so as to inject the molten resin in the cylinder at the set injection speed. Molding machine control method.

6. Computer, a molding machine including a cylinder for accommodating molten resin, a discharge nozzle communicating with the cylinder, and an injection mechanism for injecting the molten resin from the discharge nozzle by pressurizing the molten resin in the cylinder toward the discharge nozzle, the molding machine including: an acoustic emission wave information acquisition unit for acquiring acoustic emission wave information indicating the magnitude of the amplitude of an acoustic emission wave detected by an acoustic emission wave sensor that measures acoustic emission waves generated when the molten resin is pressurized; a feature amount calculation unit that calculates a feature amount of the acoustic emission wave based on the acoustic emission wave information; a fluidity index specifying unit that specifies a fluidity index indicating the fluidity of the molten resin based on a correlation between the injection speed and the feature amount when the injection speed at which the molten resin is extruded is changed; an injection speed setting unit that sets an injection speed when the molten resin in the cylinder is injected by the injection mechanism based on a target viscosity of the molten resin discharged from the discharge nozzle and the fluidity index; an injection control unit that controls the injection mechanism so as to inject the molten resin in the cylinder at the set injection speed; A program to function as a

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