Injection molding machine

Abstract

To provide an injection molding machine capable of injecting an appropriately plasticized resin into a mold.SOLUTION: There is provided an injection molding machine, comprising: a mold clamping device that performs opening, closing and mold-clamping; an injection device including a heating cylinder in which a tip communicates with a clamped mold, a screw that moves back and forth inside the heating cylinder, a hopper that supplies a granular resin to the heating cylinder, and a band heater that heats the heating cylinder; and a control device that executes an injection process in which a molten resin is injected into a cavity by forwarding the screw within the heating cylinder, a metering process in which a granular resin supplied to the heating cylinder through the hopper is plasticized by retracting the screw while rotating, and the molten resin to be subsequently injected into a space ahead of the screw of the heating cylinder is measured, and a determination process in which determination of whether or not an amount of thermal energy given to the resin in the heating cylinder is within an allowable range is performed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an injection molding machine for injecting molten resin into a mold.

Background Art

[0002] Conventionally, an injection molding machine is known that plasticizes granular pellets supplied through a hopper in a heating cylinder and injects the plasticized molten resin into a mold. In such an injection molding machine, the pellets are plasticized by supplying thermal energy to the pellets in the heating cylinder (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, if too little thermal energy is supplied to the pellets, they are injected without being sufficiently plasticized. On the other hand, if too much thermal energy is supplied to the pellets, the molten resin deteriorates in the heating cylinder. As a result, in either case, there is a possibility that defects occur in the molded product.

[0005] The present invention has been made to solve such problems of the prior art, and an object thereof is to provide an injection molding machine capable of injecting a resin that has been appropriately plasticized into a mold.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention provides an injection molding machine comprising a mold clamping device for opening and closing and clamping a mold, an injection device for injecting molten resin into a cavity of the clamped mold, and a control device for controlling the mold clamping device and the injection device. The injection device includes a heating cylinder whose tip communicates with the clamped mold, a screw that advances and retreats inside the heating cylinder, a hopper for supplying granular resin to the heating cylinder, and a band heater for heating the heating cylinder. The control device executes an injection process of injecting the molten resin into the cavity by advancing the screw in the heating cylinder, a metering process of plasticizing the granular resin supplied to the heating cylinder through the hopper by retreating the screw while rotating it, and measuring the molten resin to be injected next into the space in front of the screw in the heating cylinder, and a determination process of determining whether the amount of thermal energy applied to the resin in the heating cylinder is within an allowable range.

Advantages of the Invention

[0007] According to the present invention, an injection molding machine capable of injecting appropriately plasticized resin into a mold can be obtained.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0009] Hereinafter, the injection molding machine 10 according to the present invention will be described with reference to the drawings. The injection molding machine 10 is a device that injects a molding material measured in a mold to mold a molded product (hereinafter referred to as "injection molding").

[0010] [Configuration of Injection Molding Machine 10] FIG. 1 is a side view of the injection molding machine 10 according to the present embodiment. FIG. 2 is a hardware configuration diagram of the injection molding machine 10. As shown in FIGS. 1 and 2, the injection molding machine 10 mainly includes a mold clamping device 20, an injection device 30, and a control device 60.

[0011] The mold clamping device 20 opens, closes, and clamps the mold 21. Specifically, the mold clamping device 20 mainly includes a fixed die plate 23 that supports the fixed-side mold 22 and a movable die plate 25 that supports the movable-side mold 24. The fixed-side mold 22 and the movable-side mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the injection molding machine 10.

[0012] The movable die plate 25 moves in the left-right direction along the tie bar 27 when the driving force of the mold opening / closing motor 28 is transmitted through the toggle link mechanism 26. When the movable die plate 25 moves to the left, the fixed-side mold 22 and the movable-side mold 24 are separated. On the other hand, when the movable die plate 25 moves to the right, the fixed-side mold 22 and the movable-side mold 24 come into contact with each other, and a cavity (internal space) is formed inside the mold 21. Then, when a pressure in the direction of moving the movable die plate 25 to the right is further applied, the fixed-side mold 22 and the movable-side mold 24 are clamped.

[0013] The injection device 30 plasticizes, measures, and injects the molding material. The injection device 30 according to the present embodiment is arranged to face the mold clamping device 20 in the horizontal direction (to the right of the mold clamping device 20). The injection device 30 mainly includes a heating cylinder 31, a screw 32, a hopper 33, and a hopper block 34.

[0014] The heating cylinder 31 is a cylindrical member extending in the left - right direction of the injection molding machine 10. The heating cylinder 31 mainly includes a resin passage 35 and a nozzle 36. Further, a band heater 39 for heating the heating cylinder 31 is attached to the outer peripheral surface of the heating cylinder 31.

[0015] The resin passage 35 is a columnar space extending in the axial direction (longitudinal direction) inside the heating cylinder 31. The resin passage 35 communicates with the outside of the heating cylinder 31 (the cavity of the mold 21) through a nozzle 36 provided at the tip (front end) of the heating cylinder 31. In other words, the resin passage 35 is a space extending along the axial direction from the nozzle 36.

[0016] The screw 32 is a cylindrical member. On the outer peripheral surface of the screw 32, a groove extending spirally along the longitudinal direction of the screw 32 (hereinafter referred to as "helical groove") is formed. The screw 32 is accommodated in the internal space of the heating cylinder 31 in a state where it can move (hereinafter referred to as "advance and retreat") and rotate in the left - right direction of the injection molding machine 10. Also, the screw 32 in the heating cylinder 31 is configured to be replaceable. In other words, screws 32 with different specifications (for example, material, shape of the helical groove, volume of the helical groove) can be inserted into the heating cylinder 31.

[0017] The driving force of the injection motor 37 is transmitted to the screw 32 to cause it to advance and retreat, and the driving force of the metering motor 38 is transmitted to the screw 32 to cause it to rotate. More specifically, when the injection motor 37 rotates forward, the screw 32 moves (advances) toward the tip of the heating cylinder 31 (that is, the nozzle 36). On the other hand, when the injection motor 37 rotates in reverse, the screw 32 moves (retreats) toward the base end of the heating cylinder 31 (that is, the side opposite to the nozzle 36).

[0018] Hereinafter, among the range that the tip position of the screw 32 can reach within the heating cylinder 31, the position closest to the nozzle 36 is denoted as the "forward limit", and the position farthest from the nozzle 36 is denoted as the "retreat limit". Also, the terms "forward rotation" and "reverse rotation" of the injection motor 37 do not specify the absolute rotation direction, but only specify the relative relationship (that is, forward rotation and reverse rotation are rotations in opposite directions).

[0019] The hopper 33 is a funnel-shaped member that stores granular resin as a raw material. The hopper block 34 is a member that supports the heating cylinder 31 and the hopper 33. The hopper 33 communicates with the resin passage 35 on the base end side from the tip of the heating cylinder 31 through the hopper block 34. The granular resin stored in the hopper 33 is supplied to the resin passage 35 of the heating cylinder 31 through an opening provided at the lower end. The granular resin used in this injection molding machine 10 is, for example, a so-called "pellet" formed in a cylindrical shape.

[0020] The injection device 30 rotates the injection motor 37 in the reverse direction and rotates the metering motor 38, so that the screw 32 retreats while rotating. As a result, the pellets supplied through the hopper 33 are plasticized and filled (metered) into the resin passage 35 in front of the screw 32. Also, the injection device 30 rotates the injection motor 37 in the forward direction, so that the screw 32 advances. As a result, the plasticized resin in front of the screw 32 is injected into the cavity of the mold 21 through the nozzle 36.

[0021] The hopper 33 is supplied with resins of different types (for example, the degree of ease of plasticization) according to the molded product. Also, the particle size (grain size) of the pellets supplied to the hopper 33 varies depending on a raw material supply device (not shown) that supplies raw materials to the hopper 33. Furthermore, in addition to the pellets, recycled resin may be supplied to the hopper 33. The recycled resin refers to unnecessary parts (runners) separated from the molded product, resins discharged (purged) from the heating cylinder 31, and the like. And the ratio of the pellets and the recycled resin supplied to the hopper 33 gradually changes in the process of injection control processing described later with reference to FIG. 3.

[0022] [Configuration of the control device 60] As shown in FIG. 2, the control device 60 includes a CPU (Central Processing Unit) 61 and a memory 62. The memory 62 is composed of, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination thereof. The control device 60 realizes the processing described later by the CPU 61 reading and executing the program code stored in the ROM or HDD. The RAM is used as a work area when the CPU 61 executes the program.

[0023] However, the specific configuration of the control device 60 is not limited to this, and it may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0024] The control device 60 controls the operation of the entire injection molding machine 10. More specifically, the control device 60 controls the mold opening / closing motor 28, the injection motor 37, the metering motor 38, the band heater 39, and the communication IF (InterFace) 68 based on various signals output from the rotary encoder 64, the load cell 65 (pressure sensor), the plurality of temperature sensors 66a, 66b, 66c, and the display input device 67.

[0025] The mold opening / closing motor 28, injection motor 37, and metering motor 38 are servo motors that generate a driving force for opening and closing the mold 21, a driving force for advancing and retracting the screw 32, and a driving force for rotating the screw 32, for example, according to the control of a servo amplifier (not shown).

[0026] The rotary encoder 64 is a sensor that detects the speed and tip position of the screw 32. More specifically, the rotary encoder 64 outputs a pulse signal corresponding to the rotation of the injection motor 37 to the control device 60. Then, the control device 60 specifies the speed of the screw 32 based on the number of pulse signals output per unit time. Also, the control device 60 specifies the tip position of the screw 32 based on the cumulative value of the pulse signals.

[0027] The load cell 65 is a sensor that detects the pressure applied to the screw 32. More specifically, the load cell 65 outputs a pressure signal (voltage value) corresponding to the pressure applied to the screw 32 to the control device 60. Then, the control device 60 specifies the pressure applied to the screw 32 based on the pressure signal output from the load cell 65.

[0028] The temperature sensors 66a, 66b, and 66c detect the temperature of each region in the longitudinal direction of the heating cylinder 31 (for example, the tip region A, the intermediate region B, and the base region C), and output a temperature signal indicating the detected temperature to the control device 60. That is, the band heater 39 is configured such that the temperature of each of the tip region A, the intermediate region B, and the base region C can be individually set. Then, the temperature sensors 66a, 66b, and 66c detect the temperature of each of the tip region A, the intermediate region B, and the base region C.

[0029] The input device 67 is a user interface including a display (display device) that displays various types of information to be notified to the operator, and buttons, switches, dials, etc. (input devices) that receive input operations by the operator. The display input device 67 may include a touch panel superimposed on the display. The display input device 67 receives an input operation by the operator and outputs an input signal corresponding to the received input operation to the control device 60.

[0030] The control device 60 receives an input operation by the operator for inputting the type of the screw 32 inserted into the heating cylinder 31 and the molding conditions described later through the display input device 67. For example, every time the screw 32 is replaced, the control device 60 receives an input of the type of the new screw 32. Also, for example, every time the molded product to be molded is switched, the control device 60 receives an input of new molding conditions.

[0031] The communication IF 68 is an interface for communicating with the AI server 40 through a communication network. The communication network is composed of, for example, the Internet, a public line, a priority LAN, a wireless LAN, or a combination thereof. The control device 60 can instruct at least a part of the processing in FIG. 3 to the AI server 40 through the communication IF 68 and receive the result of the processing executed by the AI server 40 through the communication IF 68. Details of the AI server 40 will be described later with reference to FIGS. 6 and 7. Note that the functions of the AI server 40 may be implemented in the control device 60.

[0032] Also, the control device 60 may communicate with the raw material supply device through the communication IF 68. More specifically, the control device 60 may receive, through the communication IF 68, the type of the resin supplied to the hopper 33, the particle size of the pellets, and the ratio of the recycled resin from the raw material supply device. As another example, the control device 60 may receive an input operation by the operator for inputting the type of the resin supplied to the hopper 33, the particle size of the pellets, and the ratio of the recycled resin through the display input device 67.

[0033] [Information Set in the Memory 62] The memory 62 stores, in association with each other, identifiers of a plurality of screws 32 that can be inserted into the heating cylinder 31 and the specifications of the screws 32. The specifications of the screws 32 at least include the volume of the spiral grooves of the screws 32. Additionally, the specifications of the screws 32 may include the material of the screws 32, the shape of the spiral grooves, and the like.

[0034] Further, the memory 62 stores the molding conditions for injection molding. The molding conditions are the operating conditions of the injection molding machine 10 for molding a molded product. In the injection control process of FIG. 3, the control device 60 operates the injection molding machine 10 according to the molding conditions stored in the memory 62. The molding conditions according to the present embodiment include a plurality of parameters (for example, mold opening / closing speed, cooling time, ejection time, injection speed, injection stroke, heater temperatures A, B, C, screw rotation speed, pre-standby time, post-standby time). However, the parameters included in the molding conditions are not limited to these.

[0035] The parameter "mold opening / closing speed" is the speed (mm / s) at which the mold 21 switches from one of the mold open state and the mold closed state to the other. The parameter "cooling time" is the standby time (sec) from when the molten resin is injected into the mold 21 until the mold 21 is opened. The molten resin injected into the cavity of the mold 21 solidifies into a molded product during this cooling time. The parameter "ejection time" is the time (sec) required for a robot arm (not shown) to eject the molded product from the opened mold 21.

[0036] The parameter "injection speed" is the forward speed (mm / s) of the screw 32 in the injection process. The parameter "injection stroke" is the forward distance (mm) of the screw 32 in the injection process. The parameters "heater temperatures A, B, C" are the temperatures (°C) of the band heaters 39 that heat the respective regions of the heating cylinder 31 (for example, the tip region A, the middle region B, and the base region C). The parameter "screw rotation speed" is the rotation speed (rpm) of the screw 32 in the metering process. The parameter "pre-waiting time" is the waiting time (sec) from the start of the cooling process to the start of the metering. The parameter "post-waiting time" is the waiting time (sec) from the completion of the metering to the end of the cooling process. Note that at least one of the parameters "pre-waiting time" and "post-waiting time" may be 0 (sec).

[0037] Note that the parameter "screw rotation speed" is a parameter that affects the time (metering time) required to meter a predetermined amount of molten resin. More specifically, the metering time (sec) required to meter the same amount of molten resin becomes shorter as the set value of the parameter "screw rotation speed" is larger (the rotation speed of the screw 32 is faster), and becomes longer as the set value of the parameter "screw rotation speed" is smaller (the rotation speed of the screw 32 is slower). Also, the metering time refers to the time from the start of metering to the completion of metering.

[0038] [Injection Control Process] Figure 3 is a flowchart of the injection control process. The injection control process is a process of injecting the molten resin filled in the heating cylinder 31 into the cavity of the mold 21 clamped to form a molded product. The control device 60 starts the injection control process, for example, in response to the input of a molding instruction through the display input device 67. The molding instruction includes, for example, the number of molded products to be molded (hereinafter referred to as "number of moldings").

[0039] Note that at the start of the injection control process, the mold 21 is open, the molten resin to be injected next is metered in the space in front of the screw 32 of the heating cylinder 31, and it is assumed that the spiral groove of the screw 32 on the tip side from the hopper 33 is filled with resin (pellets, resin in the process of plasticization, molten resin).

[0040] First, the control device 60 closes and clamps the mold 21 by rotating the mold opening / closing motor 28 according to the molding condition "mold opening / closing speed" (S11). Thereby, a cavity is formed in the mold 21. The process of step S11 is an example of the clamping process.

[0041] Next, after the clamping process (S11) is completed, the control device 60 advances the screw 32 by rotating the injection motor 37 forward according to the molding conditions "injection speed" and "injection stroke" (S12). Thereby, the molten resin metered in the region in front of the screw 32 in the heating cylinder 31 is injected into the cavity of the mold 21. The process of step S12 is an example of the injection process.

[0042] Next, after the injection process (S12) is completed, the control device 60 cools the molten resin in the cavity according to the molding condition "cooling time" (S16). Thereby, a molded product is molded in the mold 21. At this time, the control device 60 may circulate cooling water through the cooling water channel provided in the mold 21. The process of step S16 is an example of the cooling process.

[0043] Further, after the injection process (S12) is completed, the control device 60 executes the metering process (S13 to S15) in parallel with the cooling process (S16). That is, the metering process starts simultaneously with the start of the cooling process and ends simultaneously with the end of the cooling process. The metering process is a process of plasticizing the granular resin supplied to the heating cylinder 31 through the hopper 33 while rotating and retracting the screw 32, and metering the molten resin to be next injected into the space in front of the screw 32 of the heating cylinder 31. Further, as shown in FIG. 5(A), the metering process includes at least one (more preferably, both) of the pre-waiting time from the start of the cooling process (S16) to the start of metering and the post-waiting time from the completion of metering to the end of the cooling process (S16).

[0044] More specifically, when the forming condition "pre-waiting time" has elapsed since the start of the cooling process (S16) (S13: Yes), the control device 60 reversely rotates the injection motor 37 and rotates the metering motor 38 according to the forming condition "screw rotation speed", thereby rotating and retracting the screw 32 (S14). The retraction amount of the screw 32 in the metering process coincides with the forming condition "injection stroke". Thereby, the granular resin supplied through the hopper 33 is filled (metered) into the resin passage 35 in front of the screw 32 while being plasticized. Further, the control device 60 waits until the forming condition "post-waiting time" elapses (S15).

[0045] Next, when both the cooling process (S16) and the metering process (S13 to S15) are completed (S15: Yes & S16: Yes), the control device 60 opens the mold 21 by rotating the mold opening / closing motor 28 according to the forming condition "mold opening / closing speed", and causes the robot arm to take out the molded product from the mold 21 opened according to the forming condition "take-out time" (S17). The process of step S17 is an example of the take-out process.

[0046] Next, after the weighing process (S17) is completed, the control device 60 executes a residence time control process (S18). Details of the residence time control process will be described later with reference to FIG. 4. Next, the control device 60 determines whether the number of molded products molded in the injection control process has reached the number of moldings indicated in the molding instruction (S19). Then, the control device 60 repeatedly executes the processes of steps S11 to S18 until the number of molded products molded reaches the number of moldings (S19: No). Further, when the number of molded products molded reaches the number of moldings (S19: Yes), the control device 60 ends the injection control process.

[0047] [Residence Time Control Process] FIG. 4 is a flowchart of the residence time control process. FIG. 5 is a diagram showing the relationship between the cooling process and the weighing process. The residence time control process is a process of updating the molding conditions based on the time that the resin stays in the heating cylinder 31 (hereinafter referred to as "residence time").

[0048] First, the control device 60 calculates the residence time of the resin (S21). The residence time of the resin is the time from when the resin (pellets, recycled resin) enters the heating cylinder 31 until it is injected (in other words, the time during which the resin receives thermal energy in the heating cylinder 31). First, the portion of the spiral groove of the screw 32 that is not filled with resin reaches the position facing the hopper 33 at the timing when the screw 32 advances in the injection process (S12). At this time, the resin in the hopper 33 enters the heating cylinder 31 by its own weight. Then, the resin that has entered the heating cylinder 31 gradually moves forward in the heating cylinder 31 in steps S12 to S16 that are repeatedly executed, and is injected from the heating cylinder 31 in the injection process after N (N is an integer of 1 or more) times.

[0049] The control device 60 calculates the residence time using, for example, the following (Equation 1) and (Equation 2). The number of shots is the number of times step S12 needs to be executed from when the resin enters the heating cylinder 31 until injection, and corresponds to N described above. The groove volume is the volume of the spiral groove of the screw 32 inserted into the heating cylinder 31 and is stored in the memory 62. The injection volume is the volume of the molten resin injected in one injection process and is the product of the cross-sectional area of the heating cylinder 31 and the molding condition "injection stroke". The molding cycle is the time required to execute steps S11 to S17 once. The molding cycle may be calculated from the time, speed, etc. indicated by the molding conditions, or the actual execution time may be measured.

[0050] [Number of shots] = [Groove volume] ÷ [Injection volume] ···(Equation 1) [Residence time] = [Number of shots] × [Molding cycle] ···(Equation 2)

[0051] Further, the control device 60 calculates the allowable range of the residence time of the resin (S22). The allowable range of the residence time includes at least one (preferably both) of the upper limit value and the lower limit value. The allowable range of the residence time varies based on, for example, the type of resin, the particle size of the pellets, the proportion of recycled resin, the molding conditions "heater temperatures A, B, C", etc. The control device 6 calculates the allowable range of the residence time by inputting at least one of the type of resin, the particle size of the pellets, the proportion of recycled resin, and the molding conditions "heater temperatures A, B, C" into a table or mathematical formula determined in advance by experiments or simulations.

[0052] Next, the control device 60 determines whether the residence time calculated in step S21 is within the allowable range calculated in step S22 (S23). Then, when the control device 60 determines that the residence time is outside the allowable range (S23: No), it updates the molding conditions so that the residence time falls within the allowable range (S24), and ends the residence time control process. On the other hand, when the control device 60 determines that the residence time is within the allowable range (S23: Yes), it ends the residence time control process without executing the process of step S24. The processes of steps S21 to S23 are an example of a determination process, and the process of step S24 is an example of an update process.

[0053] When the residence time is shorter than the lower limit value of the allowable range, the control device 60 may update the molding conditions so that the molding cycle becomes longer in step S24. Also, when the residence time is longer than the upper limit value of the allowable range, the control device 60 may update the molding conditions so that the molding cycle becomes shorter in step S24. The control device 60 can change the length of the molding cycle, for example, by changing at least one of the mold opening / closing speed, cooling time, take-out time, injection speed, pre-waiting time, and post-waiting time included in the molding conditions.

[0054] And as a method of changing the length of the molding cycle while maintaining the quality of the molded product (especially a method of increasing it), it is conceivable to change the length of the cooling time. Also, it is desirable to change at least one of the pre-waiting time, post-waiting time, and screw rotation speed along with changing the cooling time. That is, when the control device 60 increases the cooling time, it may increase the pre-waiting time (Fig. 5(B)), increase the post-waiting time (Fig. 5(C)), slow down the screw rotation speed (lengthen the metering time) (Fig. 5(D)), or combine these.

[0055] Then, in step S24, the control device 60 updates (overwrites with the changed molding conditions) the molding conditions stored in the memory 62. Further, after executing step S18 in FIG. 3, the control device 60 executes the processes of steps S11 to S17 according to the updated molding conditions. Note that the process of step S18 is not limited to being executed every time steps S11 to S17 are executed once, and it may be executed at the timing when the molding cycle is executed a predetermined number of times, or may be executed only once at a predetermined timing (for example, the timing when the molding cycle is stabilized) during the execution of the injection control process.

[0056] [Effects of the Embodiment] According to the above embodiment, by updating the molding conditions so that the residence time of the resin in the heating cylinder 31 falls within the allowable range, the appropriately plasticized molten resin can be injected into the mold 21. As a result, the quality of the molded product can be maintained at a high level.

[0057] Also, according to the above embodiment, by changing the cooling time in step S24, the residence time can be kept within the allowable range while maintaining the quality of the molded product. Further, by changing at least one of the pre-waiting time, the post-waiting time, and the screw rotation speed as the cooling time is changed, appropriate thermal energy can be supplied to the resin in the heating cylinder 31. As an example, when the heater temperature C in the base end region C is higher than the heater temperature A in the tip region A, the pre-waiting time may be changed. As another example, when the heater temperature A is higher than the heater temperature C, the post-waiting time may be changed.

[0058] In the above embodiment, an example of changing the length of the molding cycle to keep the residence time within the allowable range has been described. However, from the viewpoint of keeping the amount of thermal energy supplied to the resin in the heating cylinder 31 within the allowable range, at least one of the heater temperatures A to C may be changed.

[0059] In this case, the control device 60 calculates the amount of thermal energy applied to the resin in the heating cylinder 31 (S21). For example, the control device 60 calculates the amount of thermal energy by multiplying the residence time calculated by (Equation 2) by the average value of the heater temperatures A to C. Further, the control device 60 calculates an allowable range of the amount of thermal energy applied to the resin in the heating cylinder 31 (S22). The calculation method of the allowable range may be to change the output value of a table or mathematical formula determined in advance by experiments or simulations from time (sec) to the amount of thermal energy (J).

[0060] Also, the control device 60 determines whether the amount of thermal energy calculated in step S21 is within the allowable range calculated in step S22 (S23). Further, when the amount of thermal energy is outside the allowable range (S23: No), the control device 60 updates the molding conditions so that the amount of thermal energy falls within the allowable range (S24). For example, the control device 60 may change any one of the heater temperatures A to C, or may change all of the heater temperatures A to C little by little.

[0061] Furthermore, in the above embodiment, an example in which the control device 60 updates the molding conditions when the residence time (or the amount of thermal energy) is outside the allowable range has been described. However, the operator of the injection molding machine 10 may be prompted to update the molding conditions. That is, when the control device 60 determines that the residence time (or the amount of energy) is outside the allowable range (S23: No), instead of the update process (S24), it may notify the need to update the molding conditions through the display input device 67. This process is an example of a notification process. Then, when the operator updates the molding conditions through the display input device 67, the resin can be properly plasticized.

[0062] [Modification Example] Referring to FIGS. 6 and 7, the residence time control process (thermal energy amount control process) according to the modification will be described. FIG. 6 is a diagram showing a neural network included in the learned model 41. FIG. 7 is a diagram showing the relationship between the input data and the output data of the learned model 41. Note that detailed descriptions of the common points with the above-described embodiment are omitted, and the description will focus on the differences. The control device 60 according to the modification differs from the above-described embodiment in that at least a part of the determination process (S21 to S23) and the update process (S24) is executed by the learned model 41.

[0063] The AI server 40 is realized by a general-purpose computer such as a workstation or a personal computer, for example. The AI server 40 realizes an AI (Artificial Intelligence) including the learned model 41. The AI mounted on the AI server 40 is a so-called "generative AI" that processes input data to generate output data. Further, the AI mounted on the AI server 40 generates output data from the input data using, for example, the neural network shown in FIG. 6.

[0064] As shown in FIG. 6, the neural network includes an input layer L1 composed of a plurality of nodes I1, I2, I3, an intermediate layer L2 composed of a plurality of nodes H1, H2, H3, H4, and an output layer L3 composed of a plurality of nodes O1, O2, O3. In the example of FIG. 6, the number of nodes in the input layer L1 and the output layer L3 is the same, but the number of nodes in the input layer L1 and the output layer L3 may be different. Further, the neural network may have a plurality of intermediate layers L2. Furthermore, FIG. 6 shows a fully connected neural network in which a plurality of nodes constituting each of the layers L1, L2, and L3 are connected to all the nodes in the adjacent layers, but the structure of the neural network is not limited to this.

[0065] The learned model 41 is generated by inputting a plurality of learning data including input data and correct answer data into a pre-learning model (hereinafter referred to as "pre-learning model"). The input data refers to the data input into the pre-learning model. The correct answer data refers to the data that should be output when the input data is input. Then, by inputting a plurality of learning data into the pre-learning model, the neural network is optimized to become the learned model 41. This process is an example of a learning process that adjusts the weight coefficients and biases of each node so that the correct answer data is output from the output layer L3 when the input data is input to the input layer L1.

[0066] The learning data includes, for example, molding conditions in which the residence time of the resin (or the amount of thermal energy supplied to the resin) is optimized by experiments or simulations, the volume of the spiral groove (type of screw 32), the type of resin, the particle size of the pellets, the ratio of recycled resin, etc. Alternatively, a combination of molding conditions, the volume of the spiral groove (type of screw 32), the type of resin, the particle size of the pellets, the ratio of recycled resin, etc. set in the already operating injection molding machine 10 may be input into the pre-learning model as learning data.

[0067] Also, the learning process may be executed not only on the pre-learning model but also on the learned model 41. Also, the AI does not necessarily need to learn using the input data and correct answer data actually used in the present invention, and may learn using general-purpose learning data. Furthermore, the learning process executed by the AI is not limited to "supervised learning" that inputs input data and correct answer data, and may be "unsupervised learning" that does not input correct answer data, or reinforcement learning, transfer learning, etc.

[0068] Also, the AI server 40 generates and outputs output data by inputting input data into the neural network of the learned model 41. This process is an example of a generation process that generates output data by processing the input data input to the input layer L1 using the weight coefficients and biases adjusted in advance for each node and outputs the output data from the output layer L3.

[0069] As shown in FIG. 7, for example, the control device 60 according to the modified example inputs at least one of the molding conditions, the volume of the spiral groove of the screw 32, the type of resin supplied to the hopper 33, the particle size of the pellets supplied to the hopper 33, and the ratio of the recycled resin supplied to the hopper 33 to the learned model 41, and then updates the molding conditions (for example, cooling time, screw rotation speed, pre-waiting time, post-waiting time, heater temperatures A to C).

[0070] According to the modified example, by having the AI server 40 update the molding conditions, it is possible to optimize the molding conditions in which a plurality of parameters interact complexly, as compared with updating the molding conditions based on rules as in the above-described embodiment. However, it is not necessary to have the AI server 40 execute all the processes of steps S21 to S24. That is, at least a part of steps S21 to S24 may be executed by the AI server 40, and the other part may be executed by the control device 60.

[0071] The above-described embodiments are examples for explaining the present invention, and are not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the present invention in various other modes without departing from the gist of the present invention.

Explanation of Reference Numerals

[0072] 10... injection molding machine, 20... mold clamping device, 21... mold, 22... fixed-side mold, 23... fixed die plate, 24... movable-side mold, 25... movable die plate, 26... toggle link mechanism, 27... tie bar, 28... mold opening / closing motor, 30... injection device, 31... heating cylinder, 32... screw, 33... hopper, 34... hopper block, 35... resin passage, 36... nozzle, 37... injection motor, 38... metering motor, 39... band heater, 40... AI server, 41... learned model, 60... control device, 61... CPU, 62... memory, 64... rotary encoder, 65... load cell, 66a, 66b, 66c... temperature sensors, 67... display input device, 68... communication IF

Claims

1. A mold clamping device for opening, closing, and clamping a mold, an injection device for injecting molten resin into the cavity of the clamped mold, and a control device for controlling the mold clamping device and the injection device. In an injection molding machine, the injection device includes a heating cylinder whose tip communicates with the clamped mold, a screw that advances and retreats inside the heating cylinder, a hopper for supplying granular resin to the heating cylinder, and a band heater for heating the heating cylinder, and the control device performs an injection process of injecting the molten resin into the cavity by advancing the screw inside the heating cylinder, a metering process of plasticizing the granular resin supplied to the heating cylinder through the hopper by rotating and retreating the screw, and metering the molten resin to be injected next into the space in front of the screw of the heating cylinder, and a determination process of determining whether the amount of thermal energy applied to the resin in the heating cylinder is within an allowable range. An injection molding machine characterized by this is provided.

2. The control device repeatedly executes the injection process and the metering process according to molding conditions, and when it is determined in the determination process that the amount of thermal energy is outside the allowable range, an update process is executed to update the molding conditions so that the amount of thermal energy falls within the allowable range. The injection molding machine according to Claim 1 is characterized by this.

3. The control device performs a cooling process of cooling the molten resin in the cavity to form a molded product in parallel with the metering process, and in the update process, the execution time of the cooling process is updated. The injection molding machine according to Claim 2 is characterized by this.

4. The metering process includes at least one of a waiting time before starting metering from the start of the cooling process and a waiting time after ending metering until the end of the cooling process, and when the control device updates the execution time in the update process, at least one of the waiting time before, the waiting time after, and the screw rotation speed is updated. The injection molding machine according to Claim 3 is characterized by this.

5. ​ In the determination process, the control device calculates the allowable range based on at least one of the type of resin supplied to the hopper, the particle size of the granular resin supplied to the hopper, the proportion of recycled resin supplied to the hopper, and the temperature of the band heater. The injection molding machine according to claim 1, characterized in that.

6. The injection molding machine according to claim 2, characterized in that the control device causes at least a part of the determination process and the update process to be executed by a pre-trained learned model.

7. The control device is Input at least one of the molding conditions, the volume of the spiral groove of the screw, the type of resin supplied to the hopper, the particle size of the granular resin supplied to the hopper, and the proportion of recycled resin supplied to the hopper into the learned model to update the molding conditions. The injection molding machine according to claim 6, characterized in that the injection process and the metering process are executed according to the molding conditions updated by the learned model.

8. The control device is Repeatedly execute the injection process and the metering process according to the molding conditions. The injection molding machine according to claim 1, characterized in that when it is determined in the determination process that the energy amount is outside the allowable range, a notification process for notifying the necessity of updating the molding conditions is executed.

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