Control device of injection molding machine

Abstract

Provided is a technique whereby a relationship between heat transfer and shear heat generation can be easily obtained as an index of molding conditions in an injection molding machine. A control device (10) of an injection molding machine (1) is provided with: an operation information acquisition unit (11) that acquires operation information relating to the operation of heaters (24a-24d) and a screw (23); a characteristic information acquisition unit (12) that acquires characteristic information relating to characteristics of the injection molding machine (1); a heater calorific value calculation unit (13) that calculates the calorific values of the heaters (24a-24d) on the basis of the acquired operation information and characteristic information; a heater heat transfer amount calculation unit (14) that calculates the amount of heat transferred from the heaters (24a-24d) to the resin on the basis of the amount of heat generated by the heaters (24a-24d) when molding is performed in a state in which the cylinder (22) is maintained at a predetermined set temperature and the amount of heat generated by the heaters (24a-24d) when molding is stopped in a state in which the cylinder (22) is maintained at the predetermined set temperature; a shear heat generation amount calculation unit (15) that calculates a shear heat generation amount generated by the rotation of the screw (23); a plasticization index calculation unit (16) for calculating an index relating to plasticization on the basis of the heat transfer amount calculated by the heater heat transfer amount calculation unit (14) and the shear heat generation amount calculated by the shear heat generation amount calculation unit (15); and an output unit (20) that outputs the calculation result of the plasticizing index calculation unit (16).

Description

Technical Field

[0001] The present disclosure relates to a control device for an injection molding machine. Background Art

[0002] Conventionally, an injection molding machine is known that melts particles placed in a hopper in a barrel and then injects them into a mold. A heater is disposed on the outer periphery of the barrel of the injection molding machine. By heating the barrel with the heater, the particles (molding material) are melted. Further, by rotating a screw disposed in the barrel, the molding material is kneaded and plasticized. In this way, the molding material is plasticized by heat transfer from the heater and shear heat generated by the shear action when the screw rotates.

[0003] As a control method for such an injection molding machine, a method has been proposed in which a temperature difference between the temperature of the heated barrel and a previously measured barrel temperature in the heat of the heater is detected as temperature information based on shear heat (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-225372 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In addition, the ratio of heat transfer to shear heat in the heat applied to the molding material is closely related to the molten state (quality) of the plasticized molding material. Generally, if plasticization is mainly performed by heat transfer, a molding material with good quality can be obtained. On the other hand, in the case where plasticization is mainly performed by shear, plasticization can be performed efficiently.

[0009] In Patent Document 1, the energies of heat transfer and shear heat are not specifically calculated. Therefore, it is difficult to use heat transfer and shear heat to assist in determining molding conditions. Since the relationship between heat transfer and shear heat is a trade-off relationship between quality and efficiency, it is preferable if the relationship between heat transfer and shear heat can be easily obtained as an index of molding conditions.

[0010] The present disclosure has been made in view of the above problems, and an object thereof is to provide a technique capable of easily obtaining the relationship between heat transfer and shear heat as an index of molding conditions in an injection molding machine.

[0011] Means for Solving the Problems

[0012] The present disclosure relates to a control device for an injection molding machine. The injection molding machine includes a barrel, a heater disposed around the barrel, and a screw disposed inside the barrel. The control device of the injection molding machine includes: an operation information acquisition unit that acquires operation information related to the operations of the heater and the screw; a characteristic information acquisition unit that acquires characteristic information related to the characteristics of the injection molding machine; a heater heat generation amount calculation unit that calculates the heat generation amount of the heater based on the acquired operation information and characteristic information; a heater heat transfer amount calculation unit that calculates the heat transfer amount from the heater to the resin based on the heat generation amount of the heater during molding execution in a state where the barrel is maintained at a specified set temperature and the heat generation amount of the heater during molding stop in a state where the barrel is maintained at the specified set temperature; a shear heat generation amount calculation unit that calculates the shear heat generation amount generated by the rotation of the screw; a plasticization index calculation unit that calculates an index related to plasticization based on the heat transfer amount calculated by the heater heat transfer amount calculation unit and the shear heat generation amount calculated by the shear heat generation amount calculation unit; and an output unit that outputs the calculation result of the plasticization index calculation unit.

[0013] Effects of the Invention

[0014] According to the present disclosure, a technique can be provided in which the relationship between heat transfer and shear heat generation can be easily obtained as an index of molding conditions in an injection molding machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram showing the structure of an injection molding machine according to the first embodiment.

[0016] Figure 2 It is a perspective view showing a heater disposed on a barrel according to the first embodiment.

[0017] Figure 3 It is a functional block diagram of a control device for an injection molding machine according to the first embodiment.

[0018] Figure 4 It is a schematic diagram for explaining the heat balance during molding execution in the first embodiment.

[0019] Figure 5 It is a schematic diagram for explaining the heat balance during molding stop in the first embodiment.

[0020] Figure 6 It is a schematic diagram for explaining the energy balance around the barrel.

[0021] Figure 7 It is a flowchart showing an example of the process performed by the control device for an injection molding machine according to the first embodiment.

[0022] Figure 8 It is a schematic diagram showing the heat balance during molding execution of the second embodiment.

[0023] Figure 9 It is a schematic diagram showing the heat balance when molding stops in the second embodiment.

[0024] Figure 10 It is a functional block diagram of the control device of the injection molding machine according to the second embodiment.

[0025] Figure 11 It is a flowchart showing an example of the process performed by the control device of the injection molding machine according to the second embodiment.

[0026] Figure 12 It is a functional block diagram of the control device of the injection molding machine according to the third embodiment. Detailed Embodiments

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the description after the second embodiment, the same reference numerals are given to the structures common to the first embodiment, and the description thereof is appropriately omitted.

[0028] [First Embodiment]

[0029] Figure 1 It is a schematic diagram showing the structure of the injection molding machine 1 according to the first embodiment. Figure 2 It is a perspective view showing the heaters 24a to 24d of the barrel 22 disposed in the injection molding machine 1 according to the first embodiment. The injection molding machine 1 of the present embodiment includes an injection unit 2, a mold clamping unit 3, a control device 10, and a display device 6.

[0030] The injection unit 2 is an injection device including a hopper 21, a barrel 22, a screw 23, and a cooling jacket 26. The barrel 22 is, for example, a cylindrical body. Resin stored in the hopper 21 is supplied to the barrel 22. The screw 23 is disposed inside the barrel 22 and conveys the resin to the front end of the barrel 22 by rotation. The cooling jacket 26 is a device for cooling the inside of the barrel 22 (for example, a portion on the root side inside the barrel 22), and cooling water circulates in the cooling jacket 26.

[0031] As Figure 2 shown, for example, a plurality of heaters 24a to 24d are arranged along the axial direction of the barrel 22. Specifically, a plurality of heaters 24a to 24d are arranged from the nozzle portion 25 at the front end in the axial direction of the barrel 22 to the base end. In addition, the number of heaters 24a to 24d is not particularly limited.

[0032] In the present embodiment, four heaters 24a to 24d are arranged along the axial direction so as to cover the outer periphery of the barrel 22. The heater 24a is one of the front-end side heaters disposed at the front end side of the nozzle portion 25. The heaters 24b to 24d are located at positions upstream of the nozzle portion 25 in the conveying direction of the particles. The heater 24b is one of the front-end side heaters located closest to the nozzle portion 25. The heater 24d is located at the position farthest from the nozzle portion 25, and the heater 24c is located between the heater 24b and the heater 24d.

[0033] By heating the barrel 22 with the heaters 24a to 24d, the particles are melted. The melted particles are conveyed toward the nozzle portion 25 by the screw 23 and injected into the mold 5.

[0034] The mold clamping unit 3 is a device for clamping the mold 5. The molded product is formed by clamping the mold 5 by the mold clamping unit 3.

[0035] Next, the control device 10 will be described. Figure 3 It is a functional block diagram of the control device 10 of the injection molding machine 1 according to the first embodiment. The control device 10 of the injection molding machine 1 according to the first embodiment is configured by using a computer, for example, and the computer includes memories such as a ROM (read only memory) and a RAM (random access memory) that are interconnected via a bus, a CPU (control processing unit), and a communication control unit. The functions and operations of the respective functional units of the control device 10 described below are achieved by the cooperation of the CPU, the memory, and the control program stored in the memory mounted on the above computer.

[0036] The control device 10 includes an operation information acquisition unit 11, a characteristic information acquisition unit 12, a heater heat generation amount calculation unit 13, a heater heat transfer amount calculation unit 14, a shear heat generation amount calculation unit 15, a plasticization index calculation unit 16, and an output unit 20 as functional units.

[0037] The operation information acquisition unit 11 acquires operation information related to the operations of the heaters 24a to 24d. The operation information related to the heaters 24a to 24d in the present embodiment is the operation rate of each of the heaters 24a to 24d. The operation rate is an index of the operation state expressed by 0% to 100%, for example. The operation rate is determined based on the outputs such as the voltages of the heaters 24a to 24d, for example.

[0038] In addition, the operation information acquisition unit 11 also acquires information related to the operation of the screw 23 as operation information. The information related to the operation of the screw 23 is, for example, the motor current during metering, the rotational angular velocity of the screw 23, and the like.

[0039] The characteristic information acquisition unit 12 acquires characteristic information indicating the characteristics of the injection molding machine 1. The characteristic information is, for example, the capacity of the heaters 24a to 24d. The capacity of the heaters 24a to 24d mentioned here is the rated capacity such as 1500 W at 200 V.

[0040] In addition, the characteristic information acquisition unit 12 also acquires information related to the characteristics of the screw 23 as characteristic information. Information related to the characteristics of the screw 23 is, for example, the reduction ratio between the screw 23 and the motor that rotates the screw 23, the mechanical efficiency, the torque constant of the rotation motor that rotates the screw 23, and the like.

[0041] The heater heat generation amount calculation unit 13 calculates the heat generation amounts of the heaters 24a to 24d based on the acquired operation information and characteristic information. The heater heat generation amount calculation unit 13, for example, calculates the heat generation amounts of the heaters 24a to 24d within a specified time in a state where the cylinder 22 is maintained at a preset set temperature. The heater heat generation amount calculation unit 13 may also perform correction based on the difference between the rated voltage of the heaters 24a to 24d and the power supply voltage of the actual injection molding machine 1, and then calculate the heat generation amount.

[0042] An example of the calculation method of the heat generation amount performed by the heater heat generation amount calculation unit 13 will be described. For example, the heat generation amount can be calculated by the following formula (1). In addition, E in formula (1) Hi represents the heat generation amount, t 1 represents the start time of calculation, t 2 represents the end time of calculation, W i represents the heater capacity, and r i represents the heater operation rate.

[0043] [Equation 1]

[0044]

[0045] The heater heat transfer amount calculation unit 14 calculates the heat transfer amounts from the heaters 24a to 24d to the resin based on the calculation results of the heater heat generation amount calculation unit 13. An example of the calculation method for the heater heat transfer amount calculation unit 14 to calculate the heat transfer amount will be described. Let the heat transfer amounts from the heaters 24a to 24d to the resin be E Ti . When the heat generation amount during molding while maintaining the cylinder 22 at a specified set temperature is set as E Hi and the heat generation amount when molding is stopped while maintaining the cylinder 22 at a specified set temperature is set as E' Hi , the heat transfer amount has the relationship of the following formula (2). As shown in the following formula (2), the heat transfer amount can be obtained by the heat generation amount E Hi during molding execution and the heat generation amount E' when molding is stoppedHi Calculate the heat transfer amount E by the difference Ti .

[0046] [Number 2]

[0047] E Ti =E Hi -E' Hi Equation (2)

[0048] Refer to Figure 4 and Figure 5 to explain Equation (2). Figure 4 is a schematic diagram explaining the heat balance during molding execution. Figure 5 is a schematic diagram explaining the heat balance during molding stop. As Figure 4 shown, when considering the heat balance during molding execution, it can be considered that the heat generation amount E during molding execution that maintains the barrel 22 at the set temperature Hi is obtained by adding various heat dissipations to the heat transfer amount E Ti . Here, the various heat dissipations are the sum of the heat transfer amount to the front (nozzle part 25 side), the heat transfer amount to the rear (the opposite side of the nozzle part 25), and the heat dissipation amount from the surface of the heater 24b among the heat applied to the heater 24b.

[0049] On the other hand, when considering the heat balance during molding stop, different from during molding execution, the inside of the barrel 22 becomes a stagnant state where the screw 23 stops and the resin does not flow. In this state, it can be considered that the resin temperature becomes the same as the temperature of the barrel 22, so the heat generation amount of the heater 24b is not transferred to the resin. Thus, as Figure 5 shown, it can be considered that the heat generation amount E' during molding stop that maintains the barrel 22 at the set temperature Hi is equal to the various heat dissipations. It can be considered that the various heat dissipations are also the same as during molding execution, so by subtracting the heat generation amount E' Hi from the heat generation amount E Hi , the various heat dissipations are offset, and thus the heat transfer amount E Ti can be obtained.

[0050] The heater heat transfer amount calculation unit 14 of the present embodiment calculates the total heat transfer amount, which is the sum of the heat transfer amounts of the respective heaters 24a to 24d, based on the above idea. Let the sum of the heat transfer amounts from the heaters 24a to 24d to the resin be the total heat transfer amount E T . When the heat generation amounts of the respective heaters 24a to 24d during molding execution while maintaining the barrel 22 at the specified set temperature are set as E Hi and the heat generation amounts of the respective heaters 24a to 24d when molding is stopped while maintaining the barrel 22 at the specified set temperature are set as E' HiWhen it is possible to express the total heat transfer amount as shown in the following formula (3). In formula (3), i = 0, 1, 2... k.

[0051] [Equation 3]

[0052]

[0053] Next, the shear heat generation amount calculation unit 15 will be described. The shear heat generation amount calculation unit 15 calculates the shear heat generation amount generated by the rotation of the screw 23 based on the operation information acquired by the operation information acquisition unit 11 and the characteristic information acquired by the characteristic information acquisition unit 12. The shear heat generation amount is the heat generation amount caused by the shear performed by the rotation of the screw 23.

[0054] An example of the calculation method for calculating the shear heat generation amount by the shear heat generation amount calculation unit 15 will be described. For example, the shear heat generation amount can be calculated by the following formula (4). In addition, E in formula (4) S represents the shear heat generation amount of the screw, K T represents the torque constant of the rotation motor that rotates the screw, r represents the motor current during metering, R represents the reduction ratio between the motor and the screw, ω represents the rotational angular velocity of the screw, and η represents the mechanical efficiency.

[0055] [Equation 4]

[0056]

[0057] Next, the plasticization index calculation unit 16 will be described. The plasticization index calculation unit 16 calculates the total heat transfer amount of the entire barrel 22, and calculates indexes related to plasticization such as the overall plasticization state (quality) and energy efficiency inside the barrel 22 by using this total heat transfer amount.

[0058] Figure 6 is a schematic diagram showing the energy balance around the barrel 22. As Figure 6 shown, when the total heat received by the resin material is set to E M , it is possible to use the total heat transfer amount E T and the shear heat generation amount E S to express the total heat amount E as shown in the following formula (5) M .

[0059] [Equation 5]

[0060] E M = E T + E S Equation (5)

[0061] Regarding the heat dissipation amount to the surrounding environment, as long as the heat dissipation amount E to the air Ri and the heat taken away by the cooling water flowing inside the cooling jacket 26 are consideredW 、 the heat E dissipated to the machine body 0 That's all. As described above, when the calorific values of the equipment heaters 24a to 24d are E Hi , the total heat transfer amount E of all the heaters 24a to 24d can be expressed as shown in the following formula (6) T .

[0062] [Equation 6]

[0063]

[0064] Here, the index indicating the plasticization state will be described. E T ∶E S is the ratio of the heat transfer amount to the shear heat generation amount, which is the details of the total heat amount E received as the resin material. Under the condition of a ratio mainly based on the heat transfer amount, the energy efficiency is poor, but the melting quality of the resin is good. On the other hand, under the condition of a ratio mainly based on the shear heat generation amount, the energy efficiency is good, but the melting quality is poor. If the total heat transfer amount E from the heaters 24a to 24d to the resin described above can be calculated M , the ratio of the heat transfer amount to the shear heat generation amount can also be calculated. Therefore, E T ∶E T ∶E S becomes an index indicating the plasticization state.

[0065] The plasticization index calculation unit 16 of the present embodiment calculates the ratio of the heat transfer amount to the shear heat generation amount (E T ∶E S ) as an index related to plasticization based on the information of the total heat transfer amount E calculated by the heater heat transfer amount calculation unit 14 and the shear heat generation amount E calculated by the shear heat generation amount calculation unit 15. In addition, the plasticization index calculation unit 16 can also calculate the energy efficiency related to plasticization using the heater heat transfer amount. T ∶E S )

[0066] The output unit 20 will be described. The output unit 20 outputs the index related to plasticization calculated by the plasticization index calculation unit 16. In the present embodiment, the process of causing the display device 6 of the injection molding machine 1 to display the "ratio of the heat transfer amount to the shear heat generation amount (E T ∶E S )" and the "energy efficiency", which are the calculation results of the plasticization index calculation unit 16, is executed. In addition, the output unit 20 can also be configured to output the determination result of the plasticization index calculation unit 16 to a computer external to the injection molding machine 1 that is different from the display device 6 of the injection molding machine 1.

[0067] The display device 6 is an output device such as a liquid crystal display or a touch panel display. In addition, the structure may be such that, instead of the display device 6, the calculation result of the plasticization index calculation unit 16 is output by a sound output device that outputs sound.

[0068] Next, with reference to Figure 7 the process for calculating the heat transfer amount E Ti will be described. Figure 7 FIG. is a flowchart showing an example of the process performed by the control device 10 of the injection molding machine 1 according to the first embodiment.

[0069] When the process for calculating the heat transfer amount E Ti starts, the characteristic information acquisition unit 12 acquires characteristic information indicating the characteristics of the injection molding machine 1 (step S10), and the operation information acquisition unit 11 acquires the operation rate related to the operation of the heaters 24a to 24d as operation information (step S11). The operation information and the characteristic information are acquired from various sensors, a storage unit (not shown) of the control device 10, an external computer (not shown), etc., for example.

[0070] The heater heat generation amount calculation unit 13 calculates the heat generation amounts of the heaters 24a to 24d based on the acquired operation information and characteristic information (step S12). The heater heat generation amount calculation unit 13 calculates the heat generation amounts of the heaters 24a to 24d in a state where the barrel 22 is maintained at a prescribed set temperature based on the operation rates and the capacities of the heaters 24a to 24d, for example.

[0071] Next, the heater heat transfer amount calculation unit 14 calculates the heat transfer amount from the heaters 24a to 24d to the resin (step S13). The heater heat transfer amount calculation unit 14 substitutes, for example, the heat generation amount E Hi of the heaters 24a to 24d during molding execution and the heat generation amount E' Hi of the heaters 24a to 24d when molding stops into the above formula (2) to calculate the heat transfer amount E Ti from the heaters 24a to 24d to the resin. Further, the heater heat transfer amount calculation unit 14 calculates the total heat transfer amount E T of all the heaters 24a to 24d as shown in formula (3).

[0072] Next, the shear heat generation amount calculation unit 15 acquires the shear heat generation amount based on the operation information acquired by the operation information acquisition unit 11 and the characteristic information acquired by the characteristic information acquisition unit 12 (step S14).

[0073] Next, the plasticization index calculation unit 16 based on the total heat transfer amount E calculated by the heater heat transfer amount calculation unit 14 Tand the shearing heat generation amount E calculated by the shearing heat generation amount calculation unit 15 S , to calculate an index indicating the plasticization state (step S15).

[0074] When the calculation result of the plasticization index calculation unit 16 is output, the output unit 20 outputs the calculation result (step S16). The output unit 20 performs, for example, a process of causing the display device 6 to display the calculation result of the plasticization index calculation unit 16 in the form of numerical values, characters, symbols, charts, patterns, or a combination thereof.

[0075] After the process by the output unit 20 in step S15, when the control device 10 continues the molding process, the process returns to step S11, and the processes after step S11 are executed again (step S17; "Yes"). On the other hand, when the control device 10 detects the stop of the molding process, it executes a process for stopping the molding and ends the process (step S17; "No"). In addition, the continuation or stop of the molding process is determined by the control device 10 based on, for example, a user operation, whether the plasticization state satisfies a predetermined condition, and the like.

[0076] According to the control device 10 of the injection molding machine 1 according to the first embodiment described above, the following effects are achieved. That is, the injection molding machine 1 includes a barrel 22, heaters 24a to 24d disposed around the barrel 22, and a screw 23 disposed inside the barrel 22. Moreover, the control device 10 of the injection molding machine 1 includes: an operation information acquisition unit 11 that acquires operation information related to the operations of the heaters 24a to 24d and the screw 23; a characteristic information acquisition unit 12 that acquires characteristic information related to the characteristics of the injection molding machine 1; a heater heat generation amount calculation unit 13 that calculates the heat generation amounts of the heaters 24a to 24d based on the acquired operation information and characteristic information; a heater heat transfer amount calculation unit 14 that calculates the heat transfer amount from the heaters 24a to 24d to the resin based on the heat generation amounts of the heaters 24a to 24d during molding execution when the barrel 22 is maintained at a specified set temperature and the heat generation amounts of the heaters 24a to 24d when molding is stopped while the barrel 22 is maintained at the specified set temperature; a shear heat generation amount calculation unit 15 that calculates the shear heat generation amount generated by the rotation of the screw 23; a plasticization index calculation unit 16 that calculates an index related to plasticization based on the heat transfer amount calculated by the heater heat transfer amount calculation unit 14 and the shear heat generation amount calculated by the shear heat generation amount calculation unit 15; and an output unit 20 that outputs the calculation result of the plasticization index calculation unit 16. Thereby, an index indicating the plasticization state of the resin considering the shear heat generation generated by the rotation of the screw 23 can be obtained, so that the relationship between heat transfer and shear heat generation can be easily obtained as an index of molding conditions, and appropriate and efficient molding conditions can be set based on this index. In addition, since the index related to plasticization is output by the output unit 20, even during continuous molding, the user can accurately grasp the plasticization state of the resin without a special sensor. In addition, the information output by the output unit 20 can also be used in the case of finding the cause when molding defects occur.

[0077] In addition, according to the control device 10 of the injection molding machine 1 according to the present embodiment, the plasticization index calculation unit 16 calculates the ratio of the heat transfer amount from the heaters 24a to 24d to the resin to the shear heat generation amount as an index related to plasticization. Thereby, the user can grasp the plasticization quality of the resin based on the ratio of the heat transfer amount to the shear heat generation amount. For example, if the ratio of heat transfer is high, it can be known that the energy efficiency is low but the melting state of the resin is good. On the other hand, if the ratio of shear is high conversely, it can be known that the energy efficiency is high but the melting state cannot be said to be good.

[0078] [Second Embodiment]

[0079] In the second embodiment, control considering the heat dissipation of the heaters 24a to 24d is performed. Refer to Figure 8 and Figure 9, the heat balance considering the heat dissipation amount in the second embodiment will be described. Figure 8 It is a schematic diagram showing the heat balance during the molding execution in the second embodiment, Figure 9 It is a schematic diagram showing the heat balance when the molding in the second embodiment stops.

[0080] Even when the cylinder 22 is maintained at a specified set temperature, the operation rates indicating the operation states of the heaters 24a to 24d are different during the molding execution and when the molding stops. If the operation rates of the heaters 24a to 24d are different, the surface temperatures of the heaters 24a to 24d are also different, and the heat dissipation amounts from the surfaces of the heaters 24a to 24d are also different. For example, Figure 8 The heat dissipation amount E during the molding execution shown in Ri and Figure 9 The heat dissipation amount E' when the molding stops shown in Ri are different (heat dissipation amount E Ri ≠ heat dissipation amount E' Ri ). Therefore, if the difference in the heat dissipation amounts of the heaters 24a to 24d between the molding execution and when the molding stops is corrected, the heat transfer amount can be calculated more accurately.

[0081] As Figure 8 shown, it can be considered that the heat generation amount E during the molding execution Hi is obtained by adding the heat transfer amount E Ti to the heat dissipation amount E Ri and other heat dissipations obtained by removing the heat dissipation amount E Ri from various heat dissipations. Here, the other heat dissipations are the heat transfer amount in the forward direction (towards the nozzle portion 25 side) and the heat transfer amount in the backward direction (opposite side of the nozzle portion 25) in the heat transfer amount applied to the heater 24b.

[0082] The heat dissipation from the heater surface is divided into two types: convection and radiation, and the heat dissipation amount can be calculated by their total. In the second embodiment, the heater surface area, heat transfer rate, emissivity, and Stefan-Boltzmann coefficient obtained by the characteristic information acquisition unit 12 are used together with the heater surface temperature and the atmosphere temperature obtained by the operation information acquisition unit 11 to calculate the heat dissipation amount. In this calculation, the cylinder 22 can also be assumed to be a simple cylindrical shape for calculation. The atmosphere temperature and the temperature of the heater surface are obtained, for example, by using the detection values of temperature sensors (not shown) or by estimating them through a specified function.

[0083] An example of the calculation method of the heat dissipation amount will be described. For example, the following formula (7) can be used to calculate the heater convective heat dissipation amount. In addition, for example, the following formula (8) can be used to calculate the heater radiative heat dissipation amount. Furthermore, E in the formula rci represents the heater convective heat dissipation amount, and T HiRepresents the surface temperature of the heater, T C Represents the atmosphere temperature, Ai represents the surface area of the heater, h represents the heat transfer rate, E Rri Represents the radiant heat dissipation of the heater, ε represents the emissivity, σ represents the Stefan - Boltzmann coefficient.

[0084] [Number 7]

[0085]

[0086] [Number 8]

[0087]

[0088] Regarding the heat transfer amount to adjacent regions such as the front and rear in the axial direction of the cylinder 22 in a certain heater 24, it is considered that if the set temperature of the cylinder 22 is the same, the heat transfer amount hardly changes. In Figure 8 , Figure 9 's example, the heat transfer amounts to the regions of the heater 24a and the heater 24c adjacent to the region of the heater 24b do not change. Thus, it can be considered that the other heat dissipation after removing E Ri is equal to the other heat dissipation after removing E' Ri from the various heat dissipations during molding stop. In the second embodiment, the following formula (9) is used to calculate the heat transfer amount.

[0089] [Number 9]

[0090]

[0091] Based on the above idea, the total heat transfer amount, which is the sum of the heat transfer amounts of each heater 24a - 24d, is calculated. Let the sum of the heat transfer amounts from the heaters 24a - 24d to the resin be the total heat transfer amount E T . In the state where the cylinder 22 is maintained at a specified set temperature, let the heat generation amount of each heater 24a - 24d during molding execution be E Hi , and the heat dissipation amount be E Ri . In addition, in the state where the cylinder 22 is maintained at a specified set temperature, let the heat generation amount of each heater 24a - 24d when molding is stopped be E' Hi , and the heat dissipation amount be E' Ri . Then, the total heat transfer amount can be expressed as the following formula (10).

[0092] [Number 10]

[0093]

[0094] Next, a specific example of the control device 10a of the second embodiment will be described. Figure 10This is a functional block diagram of the control device 10a of the injection molding machine 1 according to the second embodiment. Figure 11 This is a flowchart showing an example of the process performed by the control device 10a of the injection molding machine 1 according to the second embodiment.

[0095] As Figure 10 shown, compared with the control device 10 of the injection molding machine 1 according to the first embodiment, the control device 10a according to the second embodiment is different in that it further includes a heater heat dissipation amount calculation unit 17 and a unit for calculating the heat transfer amount E Ti in terms of processing these, and other structures are the same as those of the first embodiment.

[0096] When the process for calculating the heat transfer amount E Ti starts, as Figure 11 shown, the characteristic information acquisition unit 12 acquires, as characteristic information, not only the capacities of the heaters 24a to 24d and the information related to the screw 23, but also the shapes of the heaters 24a to 24d and the constants related to the heat dissipation of the heaters 24a to 24d (step S20).

[0097] In addition, the operation information acquisition unit 11 acquires, as operation information, not only the operation rates of the heaters 24a to 24d and the information related to the screw 23, but also the surface temperature of the heaters and the atmosphere temperature (step S21). The constants related to heat dissipation are, for example, the heat transfer rate, the emissivity, the Stefan - Boltzmann coefficient, etc.

[0098] In addition, the heater heat generation amount calculation unit 13 calculates the heat generation amounts of the heaters 24a to 24d based on the acquired operation information and characteristic information in the same manner as in the first embodiment (step S22).

[0099] The heater heat dissipation amount calculation unit 17 calculates the heat dissipation amounts of the respective heaters 24a to 24d based on the operation information acquired by the operation information acquisition unit 11 and the characteristic information acquired by the characteristic information acquisition unit 12 (step S23). The heat dissipation amounts of the respective heaters 24a to 24d are the heat dissipation amounts in the state where the barrel 22 is maintained at a specified set temperature.

[0100] After the operation process for calculating the heat dissipation amount by the heater heat dissipation amount calculation unit 17, the heater heat transfer amount calculation unit 14 calculates the heat transfer amount E Ti from the heaters 24a to 24d to the resin (step S24). The heater heat transfer amount calculation unit 14, for example, calculates the heat generation amount E Hi and the heat dissipation amount E Ri of the heaters 24a to 24d during molding execution, and the heat generation amount E' Hi and the heat dissipation amount E' RiSubstitute into the above formula (9) to calculate the heat transfer amount E from the heaters 24a to 24d to the resin Ti Then, the heater heat transfer amount calculation unit 14 uses the calculation results of the respective heaters 24a to 24d to calculate the total heat transfer amount E of all the heaters 24a to 24d as shown in formula (10) T .

[0101] The shear heat generation amount calculation unit 15 obtains the shear heat generation amount based on the operation information obtained by the operation information acquisition unit 11 and the characteristic information obtained by the characteristic information acquisition unit 12 (step S25).

[0102] The plasticization index calculation unit 16 is based on the total heat transfer amount E calculated by the heater heat transfer amount calculation unit 14 T and the shear heat generation amount E calculated by the shear heat generation amount calculation unit 15 S , to calculate an index indicating the plasticization state (step S26). The output unit 20 performs output processing based on the calculation result of the plasticization index calculation unit 16 (step S27). The processing of step S28 is the same as that of Figure 7 step S17 of

[0103] According to the control device 10a of the injection molding machine 1 according to the second embodiment described above, the following effects are achieved.

[0104] The control device 10a of the injection molding machine 1 according to the present embodiment further includes a heater heat dissipation amount calculation unit 17 that calculates the heat dissipation amounts of the heaters 24a to 24d based on the operation information and the characteristic information. The heater heat transfer amount calculation unit 14 calculates the heat transfer amount from the heaters 24a to 24d to the resin based on the heat generation amounts of the heaters 24a to 24d during molding execution and the heat dissipation amounts calculated by the heater heat dissipation amount calculation unit 17, and the heat generation amounts of the heaters 24a to 24d during molding stop and the heat dissipation amounts calculated by the heater heat dissipation amount calculation unit 17. Thus, the heat dissipation amount from the surfaces of the heaters 24a to 24d, which has a large difference between during molding execution and during molding stop and thus has a large influence on the calculation of the heat transfer amount, is corrected, so that the heat transfer amount can be calculated more efficiently and accurately.

[0105] [Third Embodiment]

[0106] Figure 12 is a functional block diagram of the control device 10b of the injection molding machine 1 according to the third embodiment. As Figure 12 shown, compared with the control device 10 of the injection molding machine 1 according to the first embodiment, the control device 10b according to the third embodiment is different in that it further includes a cooling water heat amount calculation unit 18 and the processing for calculating the heat transfer amount E Ti , and other structures are the same as those of the first embodiment.

[0107] In the third embodiment, the operation information acquisition unit 11 acquires, as operation information, the flow rate, inlet temperature, and outlet temperature of the cooling water of the cooling jacket 26 in addition to the operation rates of the heaters 24a to 24d. In addition, the characteristic information acquisition unit 12 acquires, as characteristic information, the density and specific heat of the cooling water flowing through the cooling jacket in addition to the capacities of the heaters 24a to 24d.

[0108] The cooling water heat calculation unit 18 calculates the heat taken away by the cooling water as the increase in the internal energy of the cooling water based on the operation information acquired by the operation information acquisition unit 11 and the characteristic information acquired by the characteristic information acquisition unit 12. An example of the calculation method for calculating the heat taken away by the cooling water by the cooling water heat calculation unit 18 will be described. For example, the heat taken away by the cooling water can be calculated by the following formula (11). In addition, E in formula (11) W represents the heat taken away by the cooling water, ρ represents the density of the cooling water, c represents the specific heat of the cooling water, Q represents the flow rate of the cooling water, and T in represents the inlet temperature of the cooling water, and T out represents the outlet temperature of the cooling water.

[0109] [Equation 11]

[0110]

[0111] The heater heat transfer amount calculation unit 14 calculates the heat transfer amount from the heaters 24a to 24d to the resin based on the total heat generation amount calculated by the heater heat generation amount calculation unit 13 and the heat taken away by the cooling water calculated by the cooling water heat calculation unit 18. In a state where the barrel 22 is maintained at a specified set temperature, the heat generation amount of each of the heaters 24a to 24d during molding is set to E Hi , and the heat taken away by the cooling water is set to E w . In addition, in a state where the barrel 22 is maintained at a specified set temperature, the heat generation amount of each of the heaters 24a to 24d when molding is stopped is set to E′ Hi , and the heat taken away by the cooling water is set to E′ w . Then, the total heat transfer amount E T can be calculated using the following formula (12).

[0112] [Equation 12]

[0113]

[0114] According to the control device 10 of the injection molding machine 1 according to the third embodiment described above, the following effects are achieved. In the present embodiment, the control device 10 further includes a cooling water heat calculation unit 18 that calculates the heat taken away by the cooling water of the cooling jacket 26 based on the operation information and characteristic information including information related to the cooling jacket 26 provided in the injection molding machine 1. The heater heat transfer calculation unit 14 calculates the heat transfer amount from the heaters 24a to 24d to the resin based on the calorific value of the heaters 24a to 24d during molding execution, the heat taken away by the cooling water calculated by the cooling water heat calculation unit 18, the calorific value of the heaters 24a to 24d when molding is stopped, and the heat taken away by the cooling water calculated by the cooling water heat calculation unit 18. Even when the barrel 22 is maintained at a specified set temperature, the operating state of the cooling jacket 26 is different during molding execution and when molding is stopped. In this regard, according to the structure of the third embodiment, the difference in the cooling water heat between during molding execution and when molding is stopped is corrected, so that the heat transfer amount can be calculated more accurately.

[0115] [Fourth Embodiment]

[0116] The structure of the control device 10 according to the fourth embodiment is the same as the structure of the control device 10 of the injection molding machine 1 according to the first embodiment. In the fourth embodiment, the calculation process of the plasticization index calculation unit 16 is different from that of the first embodiment.

[0117] In the fourth embodiment, the plasticization index calculation unit 16 calculates the ratio of the sum of the calorific values of the heaters 24a to 24d and the shear calorific value to the sum of the heater heat transfer amount and the shear calorific value. Further, the plasticization index calculation unit 16 further calculates the ratio of the calorific value of the heaters 24a to 24d to the heat transfer amount of the heaters 24a to 24d to obtain the energy efficiency.

[0118] The output unit 20 outputs to the display device 6 the ratio of the sum of the calorific values of the heaters 24a to 24d and the shear calorific value to the sum of the heater heat transfer amount and the shear calorific value, and the ratio of the calorific value of the heaters 24a to 24d to the heat transfer amount, as an index related to plasticization.

[0119] According to the control device 10 of the injection molding machine 1 according to the fourth embodiment, the plasticization index calculation unit 16 calculates the ratio of the sum of the calorific values of the heaters 24a to 24d and the shear calorific value to the sum of the heat transfer amount of the heaters 24a to 24d and the shear calorific value as an index related to plasticization. Thus, the plasticization energy efficiency indicating how much energy in the energy input for plasticizing the resin by the injection molding machine 1 is transferred to the resin is calculated. Therefore, the user can determine the molding conditions based on judging the quality of the efficiency using the plasticization energy efficiency.

[0120] In addition, in the fourth embodiment, the plasticization index calculation unit 16 calculates the ratio of the calorific value of the heaters 24a to 24d to the heat transfer amount of the heaters 24a to 24d as an index related to plasticization. Thus, the energy efficiency of the heaters 24a to 24d, which indicates how much of the calorific value of the heaters is transferred to the resin, is calculated. Therefore, the user can determine the molding conditions based on the energy efficiency of the heaters 24a to 24d to judge the quality of the efficiency.

[0121] [Fifth Embodiment]

[0122] The structure of the control device 10 according to the fifth embodiment is the same as the structure of the control device 10 of the injection molding machine 1 according to the first embodiment. In the fifth embodiment, the method for calculating the heat transfer amount of the heater heat transfer amount calculation unit 14 is different from that of the first embodiment.

[0123] In the fifth embodiment, the operation information acquisition unit 11 acquires the set temperature of each control point of the cylinder 22 as operation information. It is also possible to acquire the measured temperature at each control point. In addition, the characteristic information acquisition unit 12 acquires a preset regression formula together with the capacities of the heaters 24a to 24d as characteristic information. The regression formula is obtained, for example, from a storage unit (not shown) of the control device 10.

[0124] The heater heat transfer amount calculation unit 14 calculates the calorific value required for the heaters 24a to 24d to maintain the cylinder 22 at the set temperature without using the calculation result of the heater calorific value calculation unit 13. The calorific value in the molding stop state is the heat required to maintain the cylinder 22 at the set temperature. Therefore, the heat transfer amount in the molding stop state can be uniquely determined according to the set temperature of the control points of the cylinder 22 in the molding stop state.

[0125] In the fifth embodiment, the calorific value is estimated using a regression formula that represents the relationship between the set temperature of the cylinder 22 and the calorific value, which has been obtained in advance. Thus, the effort of obtaining the calorific value through actual measurement every time the set temperature of the cylinder 22 changes can be saved. In addition, when the set temperatures of the adjacent heaters 24a to 24d are different, heat moves axially. Therefore, it is desirable to use not only the value of the target heater but also the values of the adjacent heaters in the explanatory variables of the regression formula. And in the fifth embodiment, the ambient temperature around the cylinder 22 can also be added to the explanatory variables.

[0126] [Sixth Embodiment]

[0127] The structure of the control device 10 according to the sixth embodiment is the same as that of the control device 10a of the injection molding machine 1 according to the second embodiment. In the sixth embodiment, the method for calculating the heat transfer amount by the heater heat transfer amount calculation unit 14 is different from that in the first embodiment.

[0128] In the sixth embodiment, the operation information acquisition unit 11 acquires the set temperature of each control point of the cylinder 22 as operation information. It is also possible to acquire the measured temperature at each control point. In addition, the characteristic information acquisition unit 12 acquires a preset regression formula together with the capacities of the heaters 24a to 24d as characteristic information. The regression formula is obtained from a storage unit (not shown) of the control device 10, for example.

[0129] The surface temperatures of the heaters 24a to 24d in the molding stop state are uniquely determined according to the set temperature of the cylinder. Therefore, in the ninth embodiment, based on the regression formula representing the relationship between the temperature of the cylinder 22 and the surface temperatures of the heaters 24a to 24d, the surface temperatures of the heaters 24a to 24d are estimated, and the heat dissipation amount in the molding stop state is calculated. Thus, it is possible to save the effort of obtaining the heat dissipation amount by actual measurement every time the set temperature of the cylinder 22 changes. In addition, the ambient temperature around the cylinder may be added as an explanatory variable of the regression formula.

[0130] The present disclosure has been described in detail, but the present disclosure is not limited to the above-described respective embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. within the scope not departing from the gist of the present disclosure, or within the scope not departing from the gist of the present disclosure derived from the content described in the claims and its equivalents. In addition, these embodiments can also be implemented in a combined manner. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as an example and are not limited thereto. In addition, the same applies to the cases where numerical values or mathematical formulas are used in the description of the above-described embodiments.

[0131] Regarding the above-described embodiments and modification examples, the following appended notes are also disclosed.

[0132] (Appended Note 1)

[0133] A control device (10, 10a, 10b) of an injection molding machine (1), the injection molding machine (1) including a cylinder (22), heaters (24a to 24d) disposed around the cylinder (22), and a screw (23) disposed inside the cylinder (22), the control device (10, 10a, 10b) of the injection molding machine (1) including:

[0134] An operation information acquisition unit (11) that acquires operation information related to the operations of the heaters (24a to 24d) and the screw (23);

[0135] A characteristic information acquisition unit (12) that acquires characteristic information related to the characteristics of the injection molding machine (1);

[0136] A heater heat generation amount calculation unit (13) that calculates the heat generation amount of the heaters (24a to 24d) based on the acquired operation information and characteristic information;

[0137] A heater heat transfer amount calculation unit (14) that calculates the heat transfer amount from the heaters (24a to 24d) to the resin based on the heat generation amount of the heaters (24a to 24d) during molding execution in a state where the barrel (22) is maintained at a specified set temperature and the heat generation amount of the heaters (24a to 24d) when molding is stopped in a state where the barrel (22) is maintained at the specified set temperature;

[0138] A shear heat generation amount calculation unit (15) that calculates the shear heat generation amount generated by the rotation of the screw (23);

[0139] A plasticization index calculation unit (16) that calculates an index related to plasticization based on the heat transfer amount calculated by the heater heat transfer amount calculation unit (14) and the shear heat generation amount calculated by the shear heat generation amount calculation unit (15); and

[0140] An output unit (20) that outputs the calculation result of the plasticization index calculation unit (16).

[0141] (Supplementary Note 2)

[0142] In the control devices (10, 10a, 10b) of the above injection molding machine (1),

[0143] It further includes a heater heat dissipation amount calculation unit (17), and the heater heat dissipation amount calculation unit (17) calculates the heat dissipation amount of the heaters (24a to 24d) based on the operation information and the characteristic information,

[0144] The heater heat transfer amount calculation unit (14) calculates the heat transfer amount from the heaters (24a to 24d) to the resin based on the heat generation amount of the heaters (24a to 24d) during molding execution and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit (17), and the heat generation amount of the heaters (24a to 24d) when molding is stopped and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit (17).

[0145] (Supplementary Note 3)

[0146] In the control devices (10, 10a, 10b) of the above injection molding machine (1),

[0147] It also has a cooling water heat calculation unit (18), and the cooling water heat calculation unit (18) calculates the heat taken away by the cooling water of the cooling jacket based on the operation information and the characteristic information including information related to the cooling jacket provided in the injection molding machine (1).

[0148] The heater heat transfer amount calculation unit (14) calculates the heat transfer amount from the heaters (24a to 24d) to the resin based on the heat generation amount of the heaters (24a to 24d) during molding execution, the heat taken away by the cooling water calculated by the cooling water heat calculation unit (18), the heat generation amount of the heaters (24a to 24d) when molding stops, and the heat taken away by the cooling water calculated by the cooling water heat calculation unit (18).

[0149] (Supplementary Note 4)

[0150] In the control devices (10, 10a, 10b) of the above injection molding machine (1),

[0151] The plasticization index calculation unit (16) calculates the ratio of the heat transfer amount from the heaters (24a to 24d) to the resin to the shear heat generation amount as the index related to plasticization.

[0152] (Supplementary Note 5)

[0153] In the control devices (10, 10a, 10b) of the above injection molding machine (1),

[0154] The plasticization index calculation unit (16) calculates the ratio of the sum of the heat generation amount of the heaters (24a to 24d) and the shear heat generation amount to the sum of the heat transfer amount of the heaters and the shear heat generation amount as the index related to plasticization.

[0155] (Supplementary Note 6)

[0156] In the control devices (10, 10a, 10b) of the above injection molding machine (1),

[0157] The plasticization index calculation unit (16) calculates the ratio of the heat generation amount of the heaters (24a to 24d) to the heat transfer amount of the heaters (24a to 24d) as the index related to plasticization.

[0158] Explanation of Reference Numerals

[0159] 1: Injection molding machine; 10, 10a, 10b: Control devices; 11: Motion information acquisition unit; 12: Characteristic information acquisition unit; 13: Heater heat generation amount calculation unit; 14: Heater heat transfer amount calculation unit; 15: Shear heat generation amount calculation unit; 16: Plasticization index calculation unit; 17: Heater heat dissipation amount calculation unit; 18: Cooling water heat amount calculation unit; 20: Output unit.

Claims

1. A control device for an injection molding machine, the injection molding machine including a barrel, a heater disposed around the barrel, and a screw disposed inside the barrel, the control device for the injection molding machine comprising: An operation information acquisition unit that acquires operation information related to the operations of the heater and the screw; A characteristic information acquisition unit that acquires characteristic information related to the characteristics of the injection molding machine; A heater heat generation amount calculation unit that calculates the heat generation amount of the heater based on the acquired operation information and characteristic information; A heater heat transfer amount calculation unit that calculates the heat transfer amount from the heater to the resin based on the heat generation amount of the heater during molding execution in a state where the barrel is maintained at a specified set temperature and the heat generation amount of the heater during molding stop in a state where the barrel is maintained at the specified set temperature; A shear heat generation amount calculation unit that calculates the shear heat generation amount generated by the rotation of the screw; A plasticization index calculation unit that calculates an index related to plasticization based on the heat transfer amount calculated by the heater heat transfer amount calculation unit and the shear heat generation amount calculated by the shear heat generation amount calculation unit; and An output unit that outputs the calculation result of the plasticization index calculation unit.

2. The control device for an injection molding machine according to claim 1, wherein, it further includes a heater heat dissipation amount calculation unit that calculates the heat dissipation amount of the heater based on the operation information and the characteristic information, and the heater heat transfer amount calculation unit calculates the heat transfer amount from the heater to the resin based on the heat generation amount of the heater during molding execution and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit, and the heat generation amount of the heater during molding stop and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit.

3. The control device for an injection molding machine according to claim 1, wherein, it further includes a cooling water heat amount calculation unit that calculates the heat taken away by the cooling water of the cooling jacket based on the operation information and the characteristic information including information related to the cooling jacket provided in the injection molding machine, and the heater heat transfer amount calculation unit calculates the heat transfer amount from the heater to the resin based on the heat generation amount of the heater during molding execution and the heat taken away by the cooling water calculated by the cooling water heat amount calculation unit, and the heat generation amount of the heater during molding stop and the heat taken away by the cooling water calculated by the cooling water heat amount calculation unit.

4. The control device for an injection molding machine according to any one of claims 1 to 3, wherein, the plasticization index calculation unit calculates the ratio of the heat transfer amount from the heater to the resin to the shear heat generation amount as the index related to plasticization.

5. The control device for an injection molding machine according to any one of claims 1 to 3, wherein, the plasticization index calculation unit calculates the ratio of the sum of the heat generation amount of the heater and the shear heat generation amount to the sum of the heat transfer amount of the heater and the shear heat generation amount as the index related to plasticization.

6. The control device of an injection molding machine according to claim 5, wherein, the plasticization index calculation unit calculates the ratio of the calorific value of the heater to the heat transfer amount of the heater as the index related to plasticization.

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