Injection molding apparatus

Abstract

To provide an injection molding device capable of determining whether or not a gate is clogged with high accuracy.SOLUTION: An injection molding device 1 includes: an injection device 20 provided with a nozzle 24 that discharges a molten resin; a metal mold 30 provided with a molded product cavity C and a resin channel P; in-mold resin pressure acquiring devices 331 to 334 that detect an in-mold resin pressure being the pressure of resin material in the molded product cavity C or the resin channel P; a discharge pressure acquiring device 27 for acquiring a discharge pressure of the molten resin discharged from the nozzle 24; and a determining unit 61 for determining whether or not a resin is clogged in the resin channel P by calculating a characteristic quantity based on the in-mold resin pressure acquired by the in-mold resin pressure acquiring devices 331 to 334 and a discharge pressure acquired by the discharge pressure acquiring device. The resin channel P includes: a plurality of gates P31-P34; a plurality of runners P2; and spools P1, wherein the in-mold resin pressure acquiring devices 331-334 are provided at positions near each of the plurality of gates P31-P34.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an injection molding apparatus. [Background technology]

[0002] Patent Document 1 describes a technique in which sensors are installed in the injection unit and mold of an injection molding machine, and the quality of a molded product is estimated by machine learning using the detection data of the sensors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-49929 Summary of the Invention [Problem to be solved by the invention]

[0004] Molds used in injection molding include a molded product cavity, which is the area where the molded product is formed, and a resin flow path (runner, spool (also called sprue), and gate) between the molded product cavity and the area that abuts against the nozzle of the injection device. For example, a gate in the resin flow path can become temporarily clogged due to cold slugs or foreign matter. When the gate becomes clogged, the molten resin cannot flow from the resin flow path to the molded product cavity, which can cause a decrease in dimensional accuracy of the molded product or an instability of dimensional accuracy.

[0005] When multiple molding cycles are performed consecutively to form a molded product, a temporary gate clog may occur, which then clears. Also, when a single molded product is being molded, a temporary gate clog may occur while molten resin is being supplied to the molded product cavity, which then clears during the molding of that molded product. As described above, gate clogs do not only occur continuously over a long period of time, but can also occur temporarily, making them difficult to detect. Furthermore, it is difficult to determine whether or not a resin flow path or molded product cavity is clogged from logging data, such as the injection pressure of the molten resin in the injection unit.

[0006] The present invention has been made in view of the above background, and aims to provide an injection molding apparatus that can determine with high accuracy whether or not a gate is clogged. [Means for solving the problem]

[0007] One aspect of the present invention is a molding machine including: an injection device having a nozzle that ejects molten resin; a mold including a molded product cavity and a resin flow path through which the molten resin discharged from the nozzle flows into the molded product cavity; an in-mold resin pressure acquisition device that detects an in-mold resin pressure, which is the pressure of the resin material in the molded product cavity or in the resin flow path; a discharge pressure acquisition device for acquiring a discharge pressure of the molten resin discharged from the nozzle; a determination unit that calculates a feature amount based on the resin pressure in the mold acquired by the resin pressure in the mold acquisition device and the discharge pressure acquired by the discharge pressure acquisition device, and determines whether or not the resin is clogged in the resin flow path based on the feature amount; Equipped with the resin flow path includes a plurality of gates connected to the molded product cavity, a plurality of runners connected to the plurality of gates, respectively, and a spool connected to the plurality of runners and the nozzle; The in-mold resin pressure acquisition device is provided in the mold near each of the plurality of gates. And, A control device for controlling the injection device is further provided, The control device includes: an injection step of injecting molten resin from the nozzle into the mold; Following the injection step, a pressure holding step is performed to apply a holding pressure to the molten resin in the molded product cavity. Execute a molding cycle including the determination unit determines whether or not the resin is clogged in the resin flow path based on a feature amount of the resin pressure in the mold and a feature amount of the discharge pressure in a later period of the injection process, which is a period from a time between a pressure peak at which the discharge pressure reaches a maximum value and an end time of the injection process to an end time of the injection process. In the injection molding machine. [Effects of the Invention]

[0008] When molding a molded product, molten resin is supplied from the injection device to the resin flow path in the mold, and then from the resin flow path to the molded product cavity. If a gate in the resin flow path in the mold becomes clogged during molding, the molten resin will not flow from the resin flow path to the molded product cavity, or will flow poorly. A clogged gate causes fluctuations in the resin pressure inside the mold, but if there are multiple gates, detecting the fluctuations in the resin pressure inside the mold near each gate makes it possible to more accurately detect whether or not each gate is clogged.

[0009] In the injection molding machine, the in-mold resin pressure acquisition device acquires the resin pressure in the mold near each gate, and the discharge pressure acquisition unit acquires the discharge pressure discharged from the nozzle of the injection machine, and the presence or absence of clogging of each gate is determined based on the feature values ​​calculated from these. This makes it possible to more accurately determine the presence or absence of clogging of each gate, making it possible to discover any deterioration in the dimensional accuracy of the molded product and stabilize the dimensional accuracy.

[0010] As described above, according to the above aspect, it is possible to provide an injection molding apparatus that can determine with high accuracy whether or not a gate is clogged. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the mechanical configuration of an injection molding device according to a first embodiment. [Figure 2]FIG. 2 is an enlarged cross-sectional view of the mold in FIG. 1 according to the first embodiment. [Figure 3] 2 is a view showing the space portion of the mold (molded product cavity and resin flow path) and the mold internal resin pressure acquisition unit in the first embodiment, and is a perspective view seen from the axial direction of the spool (a view seen from the right in FIG. 2). [Figure 4] 1 is a flowchart showing an injection molding method according to the first embodiment. [Figure 5] (a) Graph showing pressure changes during the injection process, the pressure holding process, and the cooling process when no gate clogging occurs, and (b) an enlarged view of the area surrounded by the two-dot chain line P in (a). [Figure 6] (a) Graph showing pressure changes during the injection process, the pressure holding process, and the cooling process when gate clogging occurs, and (b) an enlarged view of the area surrounded by the two-dot chain line P in (a). [Figure 7] FIG. 1 is a functional block diagram showing an injection molding apparatus according to a first embodiment. [Figure 8] FIG. 2 is a functional block diagram showing the processing of a gate clogging determination computer device that constitutes the injection molding apparatus of the first embodiment. [Figure 9] 5A and 5B are diagrams illustrating a feature map and determination criteria stored in a storage unit in the first embodiment. [Figure 10] FIG. 10 is a perspective view showing the space portion of the mold (molded product cavity and resin flow path) and the mold internal resin pressure acquisition unit in the second embodiment, as seen from the axial direction of the spool. [Figure 11] FIG. 10 is a functional block diagram showing an injection molding apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Embodiment 1] (1. Configuration of injection molding device 1) An injection molding apparatus 1 in embodiment 1 will be described with reference to Figure 1. Injection molding apparatus 1 is an apparatus for molding a resin molded product using a mold 30. Injection molding apparatus 1 mainly comprises a bed 10, an injection unit 20, a mold 30, a mold clamping unit 40, a control unit 50, and a computer unit 60 for determining gate clogging. Bed 10 is a member that is installed on an installation surface.

[0013] The injection device 20 is placed on the bed 10. The injection device 20 is a device that melts resin, which is a molding material, and applies pressure to the molten resin to supply it to the molded product cavity C of the mold 30. The injection device 20 includes a hopper 21, a cylinder 22, a screw 23, a nozzle 24, a heater 25, a drive device 26, and a discharge pressure acquisition device 27.

[0014] The hopper 21 is an inlet for resin pellets (granular molding material), which are the raw material for the molding material. The cylinder 22 stores molten resin produced by heating and melting the pellets fed into the hopper 21. The cylinder 22 is also provided so as to be movable in the axial direction of the cylinder 22 relative to the bed 10. The screw 23 is disposed inside the cylinder 22 and is provided so as to be rotatable and movable in the axial direction. The nozzle 24 is an outlet provided at the front end of the cylinder 22, and discharges the molten resin inside the cylinder 22 as the screw 23 moves forward.

[0015] The heater 25 is provided, for example, on the outer peripheral surface of the cylinder 22 or embedded inside the cylinder 22, and heats the resin inside the cylinder 22. That is, the heater 25 melts the pellets and maintains the molten resin in a molten state. The drive device 26 moves the cylinder 22 in the axial direction (forward and backward), rotates the screw 23, and moves it axially (forward and backward).

[0016] The discharge pressure acquisition device 27 is provided, for example, near the base end of the screw 23 and acquires discharge pressure, which is pressure data that the screw 23 receives from the molten resin in the cylinder 22 .

[0017] In addition to the discharge pressure acquisition device 27, the injection device 20 is also provided with sensors for acquiring the position of the cylinder 22, the position of the screw 23, the moving speed of the screw 23, the temperature of the heater 25, the state of the drive device 26, and the like.

[0018] The mold 30 includes a first mold 31, which is a fixed side, and a second mold 32, which is a movable side. The mold 30 forms a molded product cavity C between the first mold 31 and the second mold 32 by clamping the first mold 31 and the second mold 32 together. The first mold 31 and the second mold 32 include a resin flow path P between the molded product cavity C and a portion that abuts against the nozzle 24 of the injection device 20. The resin flow path P includes a spool P1, a runner P2, and a gate P3 as a flow path that guides the molten material supplied from the nozzle 24 of the injection device 20 to the molded product cavity C.

[0019] Furthermore, the mold 30 is equipped with an in-mold resin pressure acquisition device 33 that detects in-mold pressure data, which is the pressure of the resin material in the molded product cavity C or in the resin flow path P. The in-mold pressure data is pressure data that the inner wall surface of the molded product cavity C or the resin flow path P receives from the molten resin flowing inside the mold 30.

[0020] The mold clamping device 40 is disposed on the bed 10 opposite the injection device 20. The mold clamping device 40 opens and closes the attached mold 30, and also prevents the mold 30 from opening due to the pressure of the molten material injected into the molded product cavity C when the mold 30 is clamped.

[0021] The mold clamping unit 40 comprises a fixed platen 41, a movable platen 42, a diver 43, a drive unit 44, and a mold clamping unit measuring device 45. The first mold 31 is fixed to the fixed platen 41. The second mold 32 is fixed to the movable platen 42. The movable platen 42 can move towards and away from the fixed platen 41. The diver 43 supports the movement of the movable platen 42. The drive unit 44 is composed of, for example, a cylinder device, and moves the movable platen 42. The mold clamping unit measuring device 45 acquires the mold clamping force, mold temperature, the state of the drive unit 44, etc.

[0022] The control device 50 controls the drive device 26 of the injection device 20 and the drive device 44 of the mold clamping device 40. The computer device 60 for gate clogging determination determines whether or not each gate P3 (shown in FIG. 2) in the resin flow path P of the mold 30 is clogged. The computer device 60 for gate clogging determination is composed of an arithmetic unit, a storage device, etc., and performs processing by executing a computer program. The computer device 60 for gate clogging determination determines whether or not each gate P3 is clogged using, for example, control data from the control device 50, pressure data acquired by the discharge pressure acquisition device 27, the in-mold resin pressure acquisition device 33, etc.

[0023] (2. Detailed configuration of mold 30) The detailed configuration of the mold 30 will be described with reference to FIGS. 2 and 3. The mold 30 has a molded product cavity C for molding a molded product. The molded product cavity C is formed by a first mold 31 and a second mold 32. In this embodiment, the molded product cavity C is formed, for example, in a circular ring shape, but it can be formed in any shape, such as a C-shape or a U-shape. The molded product cavity C may be formed in only one location, or in multiple locations. For ease of explanation, only one molded product cavity C is shown in FIGS. 2 and 3.

[0024] The mold 30 also has a resin flow path P that connects the portion that contacts the nozzle 24 (shown in FIG. 1) with the molded product cavity C. The resin flow path P includes a spool P1 (also called a sprue), a runner P2, and a gate P3. The spool P1 is a passage through which the molten material is introduced from the nozzle 24. The spool P1 is formed, for example, in a straight line from the portion that contacts the nozzle 24.

[0025] The runner P2 is a flow path formed at an angle from the spool P1. That is, the molten resin introduced into the spool P1 flows into the runner P2. For example, as shown in FIG. 3, in this embodiment, multiple runners P2 are formed branching out radially from the spool P1 toward one molded product cavity C. Note that even when multiple molded product cavities C are formed, multiple runners P2 are formed branching out from the spool P1 toward each of the multiple molded product cavities C.

[0026] The gate P3 is located at the tip of the runner P2 and is connected to the molded product cavity C. It is a flow path that guides the molten resin from the runner P2 to the molded product cavity C. The cross-sectional area of ​​the flow path of the gate P3 is smaller than that of the runner P2. Multiple gates P3 are formed, connecting each of the multiple runners P2 to one molded product cavity C. Therefore, even if one of the multiple gates P3 becomes clogged, the molten resin will flow into the molded product cavity C from the other gates P3. The number of runners P2 and gates P3 is not limited, but in this embodiment, as shown in FIG. 3, four runners P2 and four gates P3 are formed. The four gates P3 (P31 to P34) are arranged at equal intervals in the circumferential direction based on the center of the spool P1 when viewed in the axial direction of the spool P1.

[0027] As shown in FIGS. 2 and 3, the mold 30 is provided with an in-mold resin pressure acquisition device 33. The in-mold resin pressure acquisition device 33 is provided in a position near each of the multiple gates P3. In this embodiment, four in-mold resin pressure acquisition devices 331 to 334 are provided. The position near each gate P3 refers to a position closer to one of the gates P3 than the center position P4 between adjacent gates P3 in the arrangement direction, as shown in FIG. 3. In other words, the in-mold resin pressure acquisition device 33 is provided at a position corresponding to the multiple gates P3. Each of the multiple in-mold resin pressure acquisition devices 33 is provided in a range that would be affected by clogging of the corresponding gate P3. In this embodiment, as shown in FIG. 2, the in-mold resin pressure acquisition device 33 is provided on the flat surface C1 of the molded product cavity C. The in-mold resin pressure acquisition device 33 acquires the pressure of the molten resin in the mold 30.

[0028] (3. Injection molding method) The injection molding method for a molded product using the injection molding apparatus 1 will be described with reference to Fig. 4. The injection molding method is carried out by a control device 50 of the injection molding apparatus 1.

[0029] First, before a series of multiple molding cycles, the control device 50 executes a purging step S1 in which the molten resin in the cylinder 22 is discharged from the nozzle 24 while the nozzle 24 is separated from the mold 30. The purging step S1 is performed, for example, to discharge thermally deteriorated resin or to replace it with a different resin material. In the purging step S1, the screw 23 is advanced, thereby discharging the molten resin in the cylinder 22 from the nozzle 24.

[0030] Next, the control device 50 executes a metering step S2 in which the screw 23 is retracted to a predetermined position while rotating the screw 23, thereby storing a predetermined amount of molten resin in front of the cylinder 22. In the metering step S2, the screw 23, which is located in a forward position, is rotated to move the molten resin toward the front end of the cylinder 22, and the screw 23 is retracted to a predetermined position by a reaction to the forward movement of the molten resin. In this way, a predetermined amount of molten resin is stored in the cylinder 22 between the tip of the screw 23 and the nozzle 24.

[0031] Next, the control device 50 executes a nozzle touch step S3 in which the cylinder 22 is advanced to bring the nozzle 24 into contact with the mold 30. At this time, the mold 30 is assumed to be clamped. However, the mold may be clamped after the nozzle touch step S3.

[0032] Next, the control device 50 executes the following molding cycles S4 to S11. The control device 50 executes the injection step S4, in which the screw 23 is advanced by controlling the speed of the screw 23, and molten resin is injected from the nozzle 24 into the mold 30. In the injection step S4, the molten resin flows from the nozzle 24 into the resin flow path P, and then flows from the resin flow path P into the molded product cavity C. In the injection step S4, the molten resin is supplied to most of the molded product cavity C (for example, 90 to 95%).

[0033] Following the injection step S4, the control device 50 executes a pressure holding step S5 in which it controls the pressure on the screw 23 to apply a holding pressure to the molten resin in the molded product cavity C. In the pressure holding step S5, by controlling the application of a predetermined pressure to the screw 23, the screw 23 is caused to move further forward and the molten resin is supplied from the nozzle 24 through the resin flow path P to the molded product cavity C. In the pressure holding step S5, the molded product cavity C is completely filled with the molten resin.

[0034] Next, the control device 50 executes a cooling step S6 in which the application of pressure to the screw 23 and the heating of the mold 30 are stopped, and the mold 30 is cooled to cool the molten resin inside the mold 30. In the cooling step S6, the molten resin inside the mold 30 solidifies. Following the cooling step S6, the control device 50 executes a mold release / molded product removal step S7 in which the control device 50 controls the mold clamping device 40 to separate the second mold 32 from the first mold 31 and remove the molded product. Next, the control device 50 controls the mold clamping device 40 to execute a mold clamping step S8 in which the second mold 32 is aligned with the first mold 31 and the molds are clamped.

[0035] Furthermore, after completing the pressure holding step S5, the control device 50 executes a nozzle separating step S9 in which the cylinder 22 is retracted to separate the nozzle 24 from the mold 30. Following the nozzle separating step S9, the control device 50 executes a metering step S10 in which the screw 23 located in a forward position is rotated to move the molten resin toward the front end side of the cylinder 22, and the screw 23 is retracted to a predetermined position by a reaction to the forward movement of the molten resin, thereby storing a predetermined amount of molten resin in front of the cylinder 22.

[0036] After the mold clamping step S8 and the measurement step S10 are completed, the control device 50 executes the nozzle touch step S11 in which the cylinder 22 is advanced to bring the nozzle 24 into contact with the mold 30. However, the mold clamping step S8 may be executed after the nozzle touch step S11. Then, after the nozzle touch step S11, the above-described injection step S4 is repeated again.

[0037] (4. Behavior of discharge pressure and pressure inside the mold) The behavior (change over time) of the acquired pressures of the in-mold resin pressure acquisition device 33 (331 to 334) and the discharge pressure acquisition device 27 during the injection process S4 and the pressure holding process S5 will be described with reference to FIGS. 5(a), (b) and 6(a), (b). First, a state in which there is no clogging at each gate P3 will be described with reference to FIGS. 5(a) and (b). It is assumed that the in-mold resin pressure acquisition device 331 acquires in-mold resin pressure A, the in-mold resin pressure acquisition device 332 acquires in-mold resin pressure B, the in-mold resin pressure acquisition device 333 acquires in-mold resin pressure C, and the in-mold resin pressure acquisition device 334 acquires in-mold resin pressure D.

[0038] 5(a) and 5(b), at time t1, the injection step S4 is started, causing the screw 23 to move forward and the discharge pressure to increase. After that, in this embodiment, the forward movement speed of the screw 23 is initially set to a low speed and then switched to a high speed.

[0039] As shown in Figures 5(a) and 5(b), when the forward speed of the screw 23 is switched to high, the molten resin flows into the resin flow path P of the mold 30, causing the discharge pressure and in-mold resin pressure to rise sharply. Then, as the resin flows into the molded product cavity C from the gate P3 of the resin flow path P, the discharge pressure and in-mold resin pressure drop slightly and then gradually rise. Therefore, in the injection step S4, the discharge pressure reaches its maximum value at the discharge pressure peak time t2. The time at which the injection step S4 ends is defined as t4, and the time between the discharge pressure peak time t2 and the injection step end time t4 is defined as t3. Time t3 is, for example, the midpoint between the pressure peak time t2 and the injection step end time t4, but it may also be a time shifted from the midpoint time.

[0040] 5(a), by switching from the injection process S4 to the dwelling process S5, the discharge pressure and the resin pressure in the mold decrease to near the desired dwelling pressure determined by the pressure control in the dwelling process S5. Usually, the discharge pressure and the resin pressure in the mold increase toward near the desired dwelling pressure immediately after decreasing to a pressure slightly lower than the desired dwelling pressure.

[0041] Then, as the dwelling step S5 continues, when the molded product cavity C is completely filled with molten resin, that is, at the time of filling completion t5, the discharge pressure and resin pressure in the mold increase. Because the discharge pressure is pressure-controlled, it reaches the desired dwell pressure immediately thereafter. Meanwhile, the resin pressure in the mold gradually increases after the time of filling completion t5.

[0042] Next, the case where gate P32 is clogged will be described with reference to Figures 6(a) and (b). Compared to the case of Figure 5(b) where there is no gate clogging, Figure 6(b) shows that the rise of in-mold resin pressure B acquired by in-mold resin pressure acquisition device 332 located near gate P32 in injection step S4 is delayed and the peak pressure in injection step S4 is reduced. On the other hand, the peak pressures of the other in-mold resin pressures A, C, and D in injection step S4 are slightly increased.

[0043] (6. Injection molding apparatus 1 of the first embodiment) An injection molding apparatus 1 of a first embodiment will be described with reference to Figures 7 and 8. As shown in Figure 7, the injection molding apparatus 1 includes an injection device 20, a mold 30, a mold clamping device 40, a control device 50, and a computer device 60. Figure 7 shows only some of the functional parts of the injection molding apparatus 1. The computer device 60 will be described below.

[0044] The computer device 60 includes a determination unit 61 and a storage unit 62. The determination unit 61 is configured by the arithmetic unit that constitutes the computer device 60 described above, and functions by executing a computer program. The storage unit 62 is configured by the storage device that constitutes the computer device 60 described above.

[0045] The determination unit 61 determines whether or not each gate P3 (P31-P34) is clogged based on the resin pressure in the mold acquired by the resin pressure acquisition device 33 and the discharge pressure acquired by the discharge pressure acquisition device 27. As described above, each gate P3 is located between the runner P2 and the molded product cavity C, and has a smaller flow path cross-sectional area than the runner P2. Therefore, there is a risk that the gate P3 may become clogged, for example, by cold slugs or foreign matter. The determination unit 61 determines whether or not each gate P3 is clogged. Furthermore, when the above-described molding cycle is performed multiple times in succession, a phenomenon may occur in which one of the gates P3 temporarily becomes clogged and then the gate clog is cleared. In this case, the determination unit 61 can determine whether or not the gate P3 is temporarily clogged.

[0046] Furthermore, the determination unit 61 determines whether or not each gate P3 is clogged based on the characteristic quantities of the in-mold resin pressures A to D and the characteristic quantities of the discharge pressure, rather than the in-mold resin pressures A to D and the discharge pressure themselves. Therefore, the determination unit 61 extracts the characteristic quantities from the acquired in-mold resin pressures A to D, and also extracts the characteristic quantities from the acquired discharge pressure.

[0047] In this embodiment, the determination unit 61 determines whether or not the gate P3 is clogged using the characteristic amount of the resin pressure in the mold during the injection process S4 (times t1 to t4) and the characteristic amount of the discharge pressure during the injection process S4. In particular, the determination unit 61 uses the characteristic amount of the resin pressure in the mold and the characteristic amount of the discharge pressure after the discharge pressure reaches its peak during the injection process S4, that is, the characteristic amount of the resin pressure in the mold and the characteristic amount of the discharge pressure during the injection process S4 from time t2 to t4.

[0048] More specifically, the judgment unit 61 uses the characteristic quantities of the resin pressures A to D in the mold during the rising portion of the pressure in the injection process S4, i.e., the characteristic quantities of the resin pressures A to D in the mold during the later time period (t3 to t4) of the injection process S4 closer to the pressure holding process S5, and the characteristic quantities of the discharge pressure during the later time period (t3 to t4) of the injection process S4 closer to the pressure holding process S5.

[0049] The feature amount may be, for example, the time integral value of the in-mold resin pressures A to D in the later time period (t3 to t4) and the time integral value of the discharge pressure in the later time period (t3 to t4). Note that the feature amount may also be the maximum value, minimum value, median, mean value, first quartile, third quartile, variance, standard deviation, kurtosis, skewness, etc. of the in-mold resin pressures A to D in the later time period (t3 to t4). The determination unit 61 may also use a plurality of feature amounts.

[0050] In this embodiment, the determination unit 61 applies machine learning to determine whether or not each of the gates P31 to P34 is clogged. Therefore, the determination unit 61 uses a trained model generated in advance to determine whether or not each of the gates P31 to P34 is clogged. In particular, when applying machine learning, the determination unit 61 can easily apply multiple feature amounts.

[0051] The storage unit 62 stores information used by the determination unit 61 to determine whether or not each of the gates P31 to P34 is clogged. In this embodiment, the storage unit 62 stores a trained model generated by machine learning using a training data set. The determination unit 61 uses the trained model stored in the storage unit 62.

[0052] The function of the computer device 60 when machine learning is applied will be described with reference to Fig. 8. In the learning phase, first, a training data set 63 is prepared. The training data set 63 includes a feature amount of the resin pressure inside the mold, a feature amount of the discharge pressure, and label data indicating the presence or absence of clogging at each of the gates P31 to P34.

[0053] In the learning phase, a machine learning processing unit 64 in the computer device 60 performs machine learning using a training dataset 63 to generate one trained model. The trained model is stored in the storage unit 62. In this embodiment, the trained model uses the feature amounts of the resin pressure in the mold and the feature amounts of the discharge pressure as explanatory variables, and the presence or absence of clogging in each of the gates P31 to P34 as a response variable.

[0054] Next, in the estimation phase, the determination unit 61 acquires the resin pressure in the mold and the discharge pressure as detection data 65. Then, the determination unit 61 calculates a feature amount of the resin pressure in the mold and a feature amount of the discharge pressure. Next, using the trained model stored in the storage unit 62, the determination unit 61 inputs the feature amount of the resin pressure in the mold and the feature amount of the discharge pressure, and thereby determines (outputs) whether or not each of the gates P31 to P34 is clogged.

[0055] In this embodiment, the presence or absence of clogging at each of the gates P31 to P34 is determined using a trained model. Alternatively, a determination criterion for determining the presence or absence of clogging at each of the gates P31 to P34 may be set in advance in the storage unit 62, and the determination unit 61 may compare the characteristic quantities of the in-mold resin pressure and the discharge pressure with the determination criterion to determine the presence or absence of clogging at each of the gates P31 to P34. In the example shown in FIG. 9, in a two-dimensional map of the in-mold resin pressure at each of the gates P31 to P34 acquired by the in-mold resin pressure acquisition devices 331 to 334 and the discharge pressure acquired by the discharge pressure acquisition device 27, a value below the determination criterion indicated by a straight line is determined to indicate the presence of a gate clogging, and a value above the determination criterion is determined to indicate the absence of a gate clogging. In this case as well, the presence or absence of a gate clogging at each of the gates P31 to P34 can be determined.

[0056] (7. Effects of the First Embodiment) When a molded product is formed, molten resin is supplied from the injection device 20 to the resin flow path P of the mold 30, and then from the resin flow path P to the molded product cavity C. If the gate P3 of the resin flow path P of the mold 30 becomes clogged during molding, the molten resin will not flow from the resin flow path P to the molded product cavity C, or will flow with difficulty.

[0057] Then, focusing on the fact that clogging of gate P3 causes fluctuations in the in-mold resin pressure in the resin flow path P, the judgment unit 61 of the injection molding apparatus 1 judges whether or not each of the gates P31 to P34 is clogged based on the characteristic amount of the in-mold resin pressure acquired by in-mold resin pressure acquisition devices 331 to 334 provided in the vicinity of each of the gates P31 to P34. By determining whether or not each of the gates P31 to P34 is clogged, it is possible to discover any deterioration in the dimensional accuracy of the molded product, and it is possible to stabilize the dimensional accuracy.

[0058] In particular, by providing in-mold resin pressure acquisition devices 331-334 in positions near each of the gates P31-P34, it is possible to detect changes in the in-mold resin pressure B acquired by the in-mold resin pressure acquisition device 332 provided in the vicinity of the gate P32 where gate clogging is occurring, as shown in Figures 5(b) and 6(b). Therefore, by using the feature amount of the in-mold resin pressure, it is possible to determine with high accuracy whether or not each of the gates P31-P34 is clogged.

[0059] Furthermore, the judgment unit 61 uses the feature quantity of the discharge pressure in addition to the feature quantity of the resin pressure inside the mold when judging whether or not the gate P3 is clogged. In the injection step S4, not only the resin pressure inside the mold but also the discharge pressure changes depending on whether or not the gate P3 is clogged. Therefore, by using the feature quantity of the discharge pressure in addition to the feature quantity of the resin pressure inside the mold, the judgment unit 61 can judge with higher accuracy whether or not each of the gates P31 to P3 is clogged.

[0060] Furthermore, the determination unit 61 uses data from the injection process S4 of the resin pressure in the mold and the discharge pressure. In particular, in the injection process S4, the pressure changes depending on whether or not the gate P3 is clogged. Therefore, by using the pressure data from the injection process S4, the determination unit 61 can determine with high accuracy whether or not each of the gates P31 to P34 is clogged.

[0061] In this embodiment, the multiple gates P31 to P34 are arranged in the circumferential direction, and the in-mold resin pressure acquisition devices 331 to 334 are provided in a position in the mold 30 that is closer to one of the multiple gates P31 to P34 than the center position P4 between adjacent gates P3. This ensures that the in-mold resin pressure acquisition devices 331 to 334 are positioned near the gates P31 to P34, making it possible to determine with high accuracy whether or not each of the gates P31 to P34 is clogged.

[0062] In this embodiment, the in-mold resin pressure acquisition devices 331-334 are provided on the flat surface C1 of the molded product cavity C. This further improves the accuracy of pressure detection by the in-mold resin pressure acquisition devices 331-334, making it possible to determine with high accuracy whether or not each of the gates P31-P34 is clogged.

[0063] This embodiment further includes a control device 50 that controls the injection device 20, and the control device 50 executes a molding cycle including an injection step S4 in which molten resin is injected from the nozzle 24 into the mold 30, and a holding pressure step S5 following the injection step S4 in which a holding pressure is applied to the molten resin in the molded product cavity C. The determination unit 61 then determines whether or not the resin is clogging each of the gates P31 to P34 based on the characteristic quantities of the in-mold resin pressures A to D in the injection step S4 and the characteristic quantity of the discharge pressure in the injection step S4. This makes it possible to determine with even greater accuracy whether or not the gates P31 to P34 are clogging.

[0064] In this embodiment, the determination unit 61 determines whether or not the resin is clogged in the resin flow path based on the characteristic amount of the resin pressure in the mold and the characteristic amount of the discharge pressure during the rise time period of the resin pressure in the mold during the injection process S4. As a result, during the rise time period of the resin pressure in the mold during the injection process S4, changes in the resin pressure in the mold due to gate clogging become more pronounced, and therefore, it is possible to determine with even greater accuracy whether or not each of the gates P31 to P34 is clogged.

[0065] In this embodiment, the judgment unit 61 judges whether or not each gate P31 to P34 is clogged with resin based on a trained model generated based on learning data including the correspondence between the characteristic amounts of the resin pressure inside the mold and the characteristic amounts of the discharge pressure and the presence or absence of resin clogging at the gate P3, or based on judgment criteria calculated from the learning data. When based on the trained model, it is possible to judge with high accuracy whether or not each gate P31 to P34 is clogged, even in products that are significantly affected by variations in materials and environment. When based on the judgment criteria, there is no need to prepare a trained model, which allows for cost reduction.

[0066] [Embodiment 2] In the injection molding apparatus 1 of the second embodiment, as shown in Fig. 10, the plurality of runners P21-P24 are connected to the plurality of gates P31-P32 arranged in the circumferential direction, respectively. The in-mold resin pressure acquisition devices 331-334 are provided in the mold 30 at positions closer to the gates P31-P34 to which the plurality of runners P21-P24 are connected, than the central positions P41-P44 between the gates P31-P34 and the spool P1. The other configurations are the same as those in the first embodiment, and therefore the same reference numerals as in the first embodiment are used and the description thereof will be omitted.

[0067] In the second embodiment, the in-mold resin pressure acquisition devices 331-334 are also provided in the vicinity of the gates P31-P34, so it is possible to determine with high accuracy whether or not each of the gates P31-P34 is clogged. However, since the runners P21-P24 are all substantially conical in shape or a combination of substantially conical and cylindrical shapes, the accuracy of detecting the in-mold resin pressure by the in-mold resin pressure acquisition devices 331-334 may be slightly lower than in the case of the flat surface C1 of the molded product cavity C in the first embodiment.

[0068] [Embodiment 3] 11, the injection molding apparatus 1 in the third embodiment further includes a computer device 60 for determining gate clogging, which further includes a viscosity normalization unit 66. The viscosity normalization unit 66 calculates a normalization coefficient that correlates with the current viscosity of the molten resin from the discharge pressure acquired by the discharge pressure acquisition device 27, and normalizes the discharge pressure and the resin pressure in the mold using the normalization coefficient. The viscosity normalization unit 66 does not acquire the viscosity of the molten resin, but estimates the degree of change in the viscosity of the molten resin from the change in the discharge pressure acquired by the discharge pressure acquisition device 27, and calculates the normalization coefficient that correlates with the current viscosity.

[0069] In the third embodiment, the determination unit 61 calculates the respective feature amounts using the discharge pressure and the in-mold resin pressure normalized by the viscosity normalization unit 66 as the determination data shown in Fig. 8, and determines whether or not there is clogging of the resin in each of the gates P31 to P34 based on the calculated feature amounts. The other configurations are the same as those in the first embodiment, and the same reference numerals as those in the first embodiment are used, and the description thereof will be omitted.

[0070] According to this embodiment 3, it is possible to calculate the characteristic quantities of the discharge pressure and the resin pressure inside the mold taking into account the change in viscosity of the molten material due to variations in material lot size and moisture content, thereby making it possible to determine with greater accuracy whether or not each gate P31 to P34 is clogged.

[0071] The present invention is not limited to the above-described embodiment and modified forms, and can be applied to various embodiments without departing from the spirit of the present invention. [Explanation of symbols]

[0072] 1: injection molding device, 20: injection device, 27: discharge pressure acquisition device, 30: mold, 33 (331 to 334): in-mold resin pressure acquisition device, 50: control device, 60: computer device, 61: determination unit, 62: memory unit, 66: viscosity normalization unit

Claims

1. an injection device having a nozzle for discharging molten resin; a mold including a molded product cavity and a resin flow path through which the molten resin discharged from the nozzle flows into the molded product cavity; an in-mold resin pressure acquisition device that detects an in-mold resin pressure, which is the pressure of the resin material in the molded product cavity or in the resin flow path; a discharge pressure acquisition device for acquiring a discharge pressure of the molten resin discharged from the nozzle; a determination unit that calculates a feature amount based on the resin pressure in the mold acquired by the resin pressure in the mold acquisition device and the discharge pressure acquired by the discharge pressure acquisition device, and determines whether or not the resin is clogged in the resin flow path based on the feature amount; Equipped with the resin flow path includes a plurality of gates connected to the molded product cavity, a plurality of runners connected to the plurality of gates, respectively, and a spool connected to the plurality of runners and the nozzle; the in-mold resin pressure acquisition device is provided in the mold near each of the plurality of gates, A control device for controlling the injection device is further provided. The control device includes: an injection step of injecting molten resin from the nozzle into the mold; Following the injection step, a pressure holding step is performed to apply a holding pressure to the molten resin in the molded product cavity. Execute a molding cycle including The judgment unit judges whether or not there is a blockage of resin in the resin flow path based on a characteristic quantity of the resin pressure in the mold and a characteristic quantity of the discharge pressure in a later period of the injection process, which is the period from the time between the pressure peak when the discharge pressure is at its maximum value in the injection process and the end time of the injection process to the end time of the injection process.

2. The plurality of gates are arranged in a circumferential direction, 2. The injection molding apparatus according to claim 1, wherein the in-mold resin pressure acquisition device is provided in the mold at a position closer to one of the plurality of gates than to a center position between adjacent gates.

3. The injection molding apparatus according to claim 2 , wherein the in-mold resin pressure acquisition device is provided on a flat surface of the molded product cavity.

4. the plurality of runners are connected to the plurality of gates arranged in the circumferential direction, respectively; 2. The injection molding apparatus of claim 1, wherein the in-mold resin pressure acquisition device is provided in the mold at a position closer to the gate than the center position between the gate and the spool to which the multiple runners are respectively connected.

5. The injection molding apparatus according to any one of claims 1 to 4, wherein the judgment unit judges whether or not there is a resin blockage in the resin flow path based on a trained model generated based on training data including a correspondence between the characteristic amounts of the resin pressure in the mold and the characteristic amounts of the discharge pressure and the presence or absence of resin blockage in the resin flow path, or based on a judgment criterion calculated from the training data.

6. a viscosity normalization unit that calculates a normalization coefficient that correlates with the current viscosity of the molten resin from the discharge pressure acquired by the discharge pressure acquisition device, and normalizes the discharge pressure and the in-mold resin pressure using the normalization coefficient; The injection molding apparatus according to any one of claims 1 to 4, wherein the determination unit calculates feature quantities of the discharge pressure and the resin pressure in the mold normalized by the viscosity normalization unit, and determines whether or not there is a blockage of resin in the resin flow path based on the feature quantities.

Images