Control device for injection-molding machine

Abstract

Provided is a technology that, in an injection-molding machine, can effectively reduce molding defects by making it possible for a user to suitably ascertain a melting state of resin. A control device 10 for an injection-molding machine 1 comprises: an operation information acquisition unit 11 that acquires operation information pertaining to operations of heaters 24a-24d; a characteristic information acquisition unit 12 that acquires characteristic information pertaining to a characteristic of the injection-molding machine 1; a heater heat generation amount calculation unit 13 that calculates the heat generation amount of the heaters 24a-24d on the basis of the acquired operation information and the acquired characteristic information; a heater heat transfer amount calculation unit 14 that calculates the heat transfer amount from the heaters 24a-24d to resin on the basis of the heat generation amount of the heaters 24a-24d at the time when molding is carried out in a state in which the cylinder 22 is maintained at a prescribed set temperature and the heat generation amount of the heaters 24a-24d at the time when the molding is stopped in the state in which the cylinder 22 is maintained at the prescribed set temperature; a melting state determination unit 15 that determines a melting state of the resin inside the cylinder 22 on the basis of a calculation result of the heater heat transfer amount calculation unit 14; and an output unit 20 that outputs a determination result of the melting state determination unit 15.

Description

Injection molding machine control device

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

[0002] Conventionally, in a control device for an injection molding machine, a technique for controlling heater output so as to maintain a control point temperature of a cylinder at a set temperature involves estimating the amount of heat and temperature (see, for example, Patent Documents 1, 2, and 3).

[0003] International Publication No. 2008 / 149742 International Publication No. 2019 / 177040 Japanese Patent Application Laid-Open No. 2010-241034

[0004] Even if the heater output is controlled to maintain the control point temperature at the set temperature, the actual measured resin temperature may differ from the set temperature. For example, if the heat supply to the resin is insufficient, the resin temperature may fall far below the set temperature. Conversely, if too much heat is supplied, the resin temperature may far exceed the set temperature. If the resin temperature deviates significantly from the set temperature, there is a high possibility of molding defects or damage to parts such as the screw and cylinder.

[0005] From the viewpoint of accuracy, it is preferable to directly control the resin temperature inside the cylinder rather than the control point temperature. However, directly measuring and controlling the temperature of the molten resin requires meeting strict conditions such as cylinder strength, sensor strength, and cost. However, when users see that the temperatures of each control point on the cylinder are maintained at a set value, they tend to assume that the resin temperature inside the cylinder has reached the set temperature. Conventional technology leaves room for improvement in terms of allowing users to properly grasp the molten state (temperature) of the resin.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that allows a user to properly understand the molten state of resin in an injection molding machine and effectively reduce molding defects.

[0007] The present disclosure relates to a control device for an injection molding machine that includes a cylinder, a heater arranged around the cylinder, and a screw arranged inside the cylinder, the control device including: an operation information acquisition unit that acquires operation information related to the operation of the heater; 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 amount of heat transfer from the heater to resin based on the heat generation amount of the heater when molding is performed with the cylinder maintained at a predetermined set temperature and the heat generation amount of the heater when molding is stopped with the cylinder maintained at the predetermined set temperature; a molten state determination unit that determines the molten state of the resin inside the cylinder based on the calculation result of the heater heat transfer amount calculation unit; and an output unit that outputs the determination result of the molten state determination unit.

[0008] According to the present disclosure, it is possible to provide a technology that allows a user to properly understand the molten state of resin in an injection molding machine and effectively reduce molding defects.

[0009] 1 is a schematic diagram showing the configuration of an injection molding machine according to a first embodiment; FIG. 2 is a perspective view showing a heater arranged in a cylinder according to the first embodiment; FIG. 3 is a functional block diagram of a control device of an injection molding machine according to the first embodiment; FIG. 4 is a schematic diagram explaining the heat balance during molding execution according to the first embodiment; FIG. 5 is a schematic diagram explaining the heat balance when molding is stopped according to the first embodiment; FIG. 6 is a flowchart showing an example of a processing flow by a control device of an injection molding machine according to the first embodiment; FIG. 7 is a schematic diagram explaining the heat balance during molding execution according to a second embodiment; FIG. 8 is a schematic diagram explaining the heat balance when molding is stopped according to the second embodiment; FIG. 9 is a functional block diagram of a control device of an injection molding machine according to a second embodiment;

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the second and subsequent embodiments, the same reference numerals will be used to designate components common to the first and second embodiments, and the description thereof will be omitted as appropriate.

[0011] [First embodiment] Fig. 1 is a schematic diagram showing the configuration of an injection molding machine 1 according to the first embodiment. Fig. 2 is a perspective view showing heaters 24a to 24d arranged in a cylinder 22 of the injection molding machine 1 according to the first embodiment. The injection molding machine 1 of this embodiment includes an injection unit 2, a mold clamping unit 3, a control device 10, and a display device 6.

[0012] The injection unit 2 is an injection device including a hopper 21, a cylinder 22, a screw 23, and a cooling jacket 26. The cylinder 22 is, for example, a cylindrical body. Resin stored in the hopper 21 is supplied to the cylinder 22. The screw 23 is disposed inside the cylinder 22 and transports the resin to the tip of the cylinder 22 by rotation. The cooling jacket 26 is a device that cools the inside of the cylinder 22 (for example, the base side portion inside the cylinder 22), and cooling water circulates through the cooling jacket 26.

[0013] 2, a plurality of heaters 24a to 24d are arranged, for example, along the axial direction of the cylinder 22. Specifically, a plurality of heaters 24a to 24d are arranged from the nozzle portion 25 at the axial tip of the cylinder 22 to the base end. The number of heaters 24a to 24d is not particularly limited.

[0014] In this embodiment, four heaters 24a to 24d are arranged along the axial direction so as to cover the outer periphery of the cylinder 22. Heater 24a is a tip heater arranged in the nozzle portion 25. Heaters 24b to 24d are located upstream of the nozzle portion 25 in the pellet conveying direction. Heater 24b is one of the tip heaters located closest to the nozzle portion 25. Heater 24d is located farthest from the nozzle portion 25, and heater 24c is located between heaters 24b and 24d.

[0015] The pellets are melted by heating the cylinder 22 with the heaters 24a to 24d. The melted pellets are transported by the screw 23 to the nozzle portion 25 side and injected into the mold 5.

[0016] The mold clamping unit 3 is a device that clamps the mold 5. When the mold clamping unit 3 clamps the mold 5, a molded product is formed.

[0017] Next, the control device 10 will be described. Fig. 3 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 using a computer including memories such as a ROM (read only memory) and a RAM (random access memory), a CPU (control processing unit), and a communication control unit, all connected to each other via a bus. The functions and operations of the functional units of the control device 10 described below are achieved by cooperation between the CPU and memory installed in the computer and the control program stored in the memory.

[0018] The control device 10 includes, as functional units, 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 melted state determination unit 15, and an output unit 20.

[0019] The operation information acquisition unit 11 acquires operation information related to the operation of the heaters 24a to 24d. In this embodiment, the operation information related to the heaters 24a to 24d is the operation rate of each of the heaters 24a to 24d. The operation rate is an index of the operation state indicated, for example, from 0 to 100%. The operation rate is determined based on the output, such as the voltage, of the heaters 24a to 24d, for example.

[0020] 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 here is a rated capacity of 1500 W at 200 V.

[0021] 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 calculates, for example, the heat generation amount per unit time of each of the heaters 24a to 24d in a state in which the cylinder 22 is maintained at a preset temperature. The heater heat generation amount calculation unit 13 may calculate the heat generation amount by making corrections based on the difference between the rated voltage of the heaters 24a to 24d and the actual power supply voltage of the injection molding machine 1.

[0022] An example of a method for calculating the heat generation amount by the heater heat generation amount calculation unit 13 will be described. The heat generation amount can be calculated, for example, by the following formula (1). Note that P Ｈｉ is the amount of heat generated per unit time, t １ is the calculation start time, t ２ is the calculation end time, W ｉ is the heater capacity, r ｉ indicates the heater operation rate.

[0023]

[0024] The heater heat transfer amount calculation unit 14 calculates the amount of heat transferred from each of the heaters 24a to 24d to the resin based on the calculation result of the heater heat generation amount calculation unit 13. An example of a method for calculating the amount of heat transfer by the heater heat transfer amount calculation unit 14 will be described. The amount of heat transferred per unit time from the heaters 24a to 24d to the resin is expressed as P Ｔｉ The heat generation amount per unit time during molding is set as P when the cylinder 22 is maintained at a predetermined set temperature. Ｈｉ The heat generation per unit time when molding is stopped is P' Ｈｉ As a result, the heat transfer amount is expressed by the following formula (2): As shown in the formula (2), the heat generation amount P Ｈｉ and the heat generation amount P' when molding stops Ｈｉ The difference between the heat transfer amount P Ｔｉ It is possible to calculate the following.

[0025]

[0026] The formula (2) will be explained with reference to Fig. 4 and Fig. 5. Fig. 4 is a schematic diagram for explaining the heat balance during molding. Fig. 5 is a schematic diagram for explaining the heat balance when molding is stopped. As shown in Fig. 4, when considering the heat balance during molding, the heat generation amount P during molding to maintain the cylinder 22 at the set temperature is Ｈｉ is the heat transfer amount P Ｔｉ Here, the various types of heat radiation are the sum of the amount of heat transferred to the heater 24b, the amount of heat transferred to the front (toward the nozzle portion 25), the amount of heat transferred to the rear (the opposite side of the nozzle portion 25), and the amount of heat radiation from the surface of the heater 24b.

[0027] On the other hand, when considering the heat balance when molding is stopped, unlike when molding is in progress, the screw 23 stops and the resin does not flow inside the cylinder 22, resulting in a stagnant state. In this state, it can be considered that the resin temperature is the same as the temperature of the cylinder 22, so the heat generated by the heater 24b is not transmitted to the resin. Therefore, as shown in Figure 5, the heat generation amount P' when molding is stopped, which maintains the cylinder 22 at the set temperature, Ｈｉ It can be considered that the heat dissipation is equal to the heat dissipation during molding. Ｈｉ From the calorific value P' Ｈｉ By subtracting the above, various heat dissipation is offset and the heat transfer amount P Ｔｉ can be obtained.

[0028] 3, the melted state determination unit 15 will be described. The melted state determination unit 15 determines the melted state of the resin inside the cylinder 22 based on the calculation result of the heater heat transfer amount calculation unit 14.

[0029] The amount of heat transferred from the heaters 24a to 24d to the resin is P Ｔｉ is closely related to the resin temperature inside the cylinder 22. For example, if the resin does not receive a sufficient amount of heat upstream of a certain heater zone in the resin conveying direction, the resin sent to that zone will be at a temperature lower than the set temperature of the heaters 24a to 24d. In this case, a large amount of heat is transferred from the heaters 24a to 24d to the resin, so the heat transfer amount P Ｔｉ Conversely, if the resin is receiving an excessive amount of heat upstream of a certain heater zone in the resin conveying direction, the resin sent to that zone will have a temperature higher than the set temperature of the heaters 24a to 24d, and the heat transfer amount P Ｔｉ That is, the difference between the resin temperature deviation from the set temperature of each of the heaters 24a to 24d and the heat transfer amount P Ｔｉ There is a negative correlation between

[0030] The melting state determination unit 15 of this embodiment determines the "deviation of the resin temperature from the set temperature of each of the heaters 24a to 24d" and the "amount of heat transfer P Ｔｉ By utilizing the correlation between the temperature and the melting point, the melting state of the resin is calculated as the degree of deviation from the heater set temperature.

[0031] The output unit 20 will now be described. The output unit 20 outputs the determination result of the melted state by the melted state determination unit 15 so that the user can understand the melted state. In this embodiment, the output unit 20 executes a process of displaying the determination result of the melted state determination unit 15 on the display device 6 of the injection molding machine 1. Note that the output unit 20 may be configured to output the determination result of the melted state determination unit 15 to an external computer connected to the injection molding machine 1 that is different from the display device 6 of the injection molding machine 1.

[0032] The display device 6 is, for example, an output device such as a liquid crystal display, a touch panel display, etc. Instead of the display device 6, the determination result of the melted state determination unit 15 may be output by a sound output device that outputs sound.

[0033] Next, referring to FIG. 6, the heat transfer amount P Ｔｉ 6 is a flowchart showing an example of the flow of processing by the control device 10 of the injection molding machine 1 according to the first embodiment.

[0034] Heat transfer amount P Ｔｉ When the process for calculating the above is started, 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 availability rates related to the operations of the heaters 24a to 24d as operation information (step S11). The operation information and characteristic information are acquired, for example, from various sensors, a storage unit (not shown) of the control device 10, an external computer (not shown), etc.

[0035] 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 per unit time of the heaters 24a to 24d in a state in which the cylinder 22 is maintained at a predetermined set temperature based on, for example, the operation rates and capacities of the heaters 24a to 24d.

[0036] Next, the heater heat transfer amount calculation unit 14 calculates the amount of heat transferred from the heaters 24a to 24d to the resin (step S13). The heater heat transfer amount calculation unit 14 calculates, for example, the heat generation amount PＨｉ and the heat generation amount P' of the heaters 24a to 24d when molding is stopped. Ｈｉ and are substituted into the above equation (2), the amount of heat transferred from the heaters 24a to 24d to the resin P Ｔｉ Calculate the following.

[0037] Next, the melting state determination unit 15 calculates the heat transfer amount P Ｔｉ The melting state determination unit 15 determines the melting state based on, for example, "the deviation of the resin temperature from the set temperature of each of the heaters 24a to 24d" and "the amount of heat transfer P Ｔｉ " is used to output information indicating the degree of melting based on preset conditions. The information indicating the degree of melting may be a numerical value, or may be a character, symbol, graph, picture, or combination thereof indicating a state corresponding to the numerical value.

[0038] When the determination result is output by the melted state determination unit 15, the output unit 20 outputs the determination result (step S15). The output unit 20 executes a process of displaying the determination result by the melted state determination unit 15 on the display device 6, for example, in the form of a numerical value, a letter, a symbol, a graph, a picture, or a combination thereof.

[0039] After the processing by the output unit 20 in step S15, if the molding process is to be continued, the control device 10 returns to step S11 and executes the processes from step S11 onwards again (step S16; Yes). On the other hand, if the control device 10 detects that the molding process has stopped, it executes a process to stop the molding and ends the flow (step S16; No). Note that the continuation or stop of the molding process is determined by the control device 10 based on, for example, whether the user's operation or the melted state satisfies predetermined conditions, etc.

[0040] The control device 10 of the injection molding machine 1 according to the first embodiment described above has the following advantages: The injection molding machine 1 includes 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 of the injection molding machine 1 comprises an operation information acquisition unit 11 that acquires operation information related to the operation of the heaters 24a to 24d, 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 amount of heat transfer from the heaters 24a to 24d to the resin based on the heat generation amounts of the heaters 24a to 24d when molding is performed with the cylinder 22 maintained at a predetermined set temperature and the heat generation amounts of the heaters 24a to 24d when molding is stopped with the cylinder 22 maintained at the predetermined set temperature, a molten state determination unit 15 that determines the molten state of the resin inside the cylinder 22 based on the calculation result of the heater heat transfer amount calculation unit 14, and an output unit 20 that outputs the determination result of the molten state determination unit 15. As a result, the information on the melting state output by the output unit 20 allows the user to accurately grasp the melting state of the resin even during continuous molding without the need for a special sensor. Being able to grasp the melting state allows the user to determine whether the molding conditions are good or bad, allowing for appropriate adjustment of the molding conditions. Furthermore, the information output by the output unit 20 can also be used to identify the cause of molding defects or damage to the screw 23 or cylinder 22.

[0041] Second Embodiment In a second embodiment, control is performed taking into consideration the amount of heat dissipation from the heaters 24a to 24d. The heat balance taking into consideration the amount of heat dissipation in the second embodiment will be described with reference to Figures 7 and 8. Figure 7 is a schematic diagram illustrating the heat balance during molding in the second embodiment, and Figure 8 is a schematic diagram illustrating the heat balance when molding is stopped in the second embodiment.

[0042] Even when the cylinder 22 is maintained at a predetermined set temperature, the operating rate indicating the operating state of the heaters 24a to 24d differs between when molding is in progress and when molding is stopped. If the operating rate of the heaters 24a to 24d differs, the surface temperature of the heaters 24a to 24d also differs, and the amount of heat radiation from the surfaces of the heaters 24a to 24d also differs. For example, the amount of heat radiation P per unit time during molding as shown in FIG. Ｒｉ and the heat dissipation amount P' per unit time when molding is stopped as shown in FIG. Ｒｉ and are different (heat dissipation amount P Ｒｉ ≠ Heat radiation amount P' Ｒｉ Therefore, if the difference in the amount of heat radiation from the heaters 24a to 24d when molding is in progress and when molding is stopped is corrected, the amount of heat transfer can be calculated more accurately.

[0043] Heat generation during molding P Ｈｉ is the heat transfer amount P Ｔｉ In contrast, the heat dissipation amount P Ｒｉ and the heat dissipation amount P Ｒｉ Here, the other heat radiation is the amount of heat transferred to the heater 24b toward the front (the nozzle portion 25 side) and the amount of heat transferred to the rear (the opposite side of the nozzle portion 25).

[0044] Heat dissipation from the heater surface can be divided into two types: convection and radiation, and the amount of heat dissipation can be calculated by summing them. In the second embodiment, the amount of heat dissipation is calculated using the heater surface temperature and ambient temperature acquired by the operation information acquisition unit 11, as well as the heater surface area, heat transfer coefficient, emissivity, and Stefan-Boltzmann coefficient acquired by the characteristic information acquisition unit 12. In this calculation, the cylinder 22 may be assumed to have a simple cylindrical shape. The ambient temperature and heater surface temperature are acquired, for example, by using the detected value of a temperature sensor (not shown) or by estimating them using a predetermined function.

[0045] An example of a method for calculating the amount of heat radiation will be described. The amount of convective heat radiation from the heater can be calculated, for example, using the following formula (3). The amount of radiative heat radiation from the heater can be calculated, for example, using the following formula (4). Note that P ｒｃｉ is the amount of heat dissipated by the heater, T Ｈｉ is the heater surface temperature, T Ｃis the ambient temperature, A ｉ is the heater surface area, h is the heat transfer coefficient, P Ｒｒｉ represents the heater radiation heat loss, ε represents the emissivity, and σ represents the Stefan-Boltzmann coefficient.

[0046]

[0047]

[0048] It is considered that the amount of heat transferred from a heater 24 to adjacent zones, such as the front or rear zone in the axial direction of the cylinder 22, hardly changes if the set temperature of the cylinder 22 is the same. In the examples of Figures 7 and 8, the amount of heat transferred to the zone of heater 24a or the zone of heater 24c adjacent to the zone of heater 24b does not change. Therefore, P Ｒｉ P' from other heat dissipation excluding P' and various heat dissipation when molding is stopped Ｒｉ In the second embodiment, the amount of heat transfer is calculated using the following equation (5):

[0049]

[0050] Next, a specific example of the control device 10a of the second embodiment will be described. Fig. 9 is a functional block diagram of the control device 10a of the injection molding machine 1 according to the second embodiment. Fig. 10 is a flowchart showing an example of the flow of processing by the control device 10a of the injection molding machine 1 according to the second embodiment.

[0051] As shown in FIG. 9, the control device 10a according to the second embodiment is different from the control device 10 of the injection molding machine 1 according to the first embodiment in that it further includes a heater heat radiation amount calculation unit 17 and a heat transfer amount P Ｔｉ The processing for calculating the above difference is different, and the other configurations are the same as those of the first embodiment.

[0052] Heat transfer amount P Ｔｉ When the process for calculating is started, as shown in FIG. 10, the characteristic information acquisition unit 12 acquires the capacity of the heaters 24a to 24d as well as the shapes of the heaters 24a to 24d and constants related to the heat dissipation of the heaters 24a to 24d as characteristic information (step S20).

[0053] The operation information acquiring unit 11 acquires the heater surface temperature and the ambient temperature as operation information in addition to the operating rates of the heaters 24a to 24d (step S21). The constants related to heat dissipation include, for example, the heat transfer coefficient, the emissivity, and the Stefan-Boltzmann coefficient.

[0054] Furthermore, similarly to the first embodiment, 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 S22).

[0055] The heater heat dissipation amount calculation unit 17 calculates the heat dissipation amount of each of the heaters 24 a to 24 d 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 amount of each of the heaters 24 a to 24 d is the heat dissipation amount per unit time when the cylinder 22 is maintained at a predetermined set temperature.

[0056] After the calculation of the heat radiation amount by the heater heat radiation amount calculation unit 17, the heater heat transfer amount calculation unit 14 calculates the heat transfer amount P Ｔｉ The heater heat transfer amount calculation unit 14 calculates, for example, the heat transfer amount P Ｈｉ and heat dissipation amount P Ｒｉ and the heat generation amount P' of the heaters 24a to 24d when molding is stopped. Ｈｉ and heat dissipation amount P' Ｒｉ and the amount of heat transferred from the heaters 24a to 24d to the resin P Ｔｉ Calculate the following.

[0057] The melting state determination unit 15 determines the heat transfer amount P Ｔｉ The output unit 20 performs output processing based on the determination result of the melted state determination unit 15 (step S26). The processing in step S27 is the same as the processing in step S16 in FIG.

[0058] The control device 10a of the injection molding machine 1 according to the second embodiment described above provides the following effects.

[0059] The control device 10a of the injection molding machine 1 according to this 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, and the heater heat transfer amount calculation unit 14 calculates the amount of heat transfer from the heaters 24a to 24d to the resin based on the heat generation amounts of the heaters 24a to 24d during molding and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit 17, and the heat generation amounts 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. This corrects the amount of heat dissipation from the surfaces of the heaters 24a to 24d, which differs greatly between when molding is in progress and when molding is stopped and has a significant impact on the calculation of the heat transfer amount, making it possible to calculate the heat transfer amount more efficiently and accurately.

[0060] [Third embodiment] The control device 10 according to the third embodiment has a common configuration with the control device 10 of the injection molding machine 1 according to the first embodiment. In the third embodiment, the determination method of the molten state determination unit 15 is different from the determination method in the first embodiment.

[0061] What interests users most is the molten state of the resin injected into the mold 5, in other words, the molten state of the metered resin. There is a negative correlation between the resin temperature of the metered resin at the tip of the screw 23 and the deviation from the set temperature of the heater 24a or 24b located on the tip side of the cylinder 22.

[0062] Figure 11 is a graph showing the relationship between the amount of heat transfer of the metered resin and the deviation between the resin temperature and the set temperature. The horizontal axis of the graph in Figure 11 represents the amount of heat transfer from the heater 24b, and the vertical axis represents the experimental results showing the degree of deviation between the resin temperature and the set temperature. This experiment was conducted using the same molding machine, screw cylinder, and resin material, with various plasticization conditions changed except for the metering stroke. The approximate line in Figure 11 also shows a very strong negative correlation between the amount of heat transfer from the heater 24b and the deviation between the resin temperature and the set temperature. In other words, if the amount of heat transfer is very large, the resin may not receive enough heat in the supply section where the resin is supplied or the compression section where the resin is compressed, resulting in the metering of resin at a temperature lower than the set temperature, which may lead to poor filling and molding defects. Furthermore, when the resin temperature is low, the resin's high viscosity places a heavy load on the parts at the tip of the screw 23, potentially causing damage. Conversely, if the heat transfer rate is low, too much heat may be applied, causing the metering resin to become too hot, which may result in thermal degradation.

[0063] Therefore, in the third embodiment, in order to accurately determine the molten state of the metered resin by utilizing this correlation in the metered resin, the object to be determined by the molten state determination unit 15 is the heater 24a of the nozzle portion 25 closest to the metered resin or the heater 24b at the tip side of the cylinder 22.

[0064] The object to be judged may be selected based on, for example, the relationship between the volume of the resin to be injected (one-shot volume) and the internal volume of the nozzle portion 25. If the volume of the resin to be injected is judged to be large in relation to the internal volume of the nozzle portion 25, the heater 24b on the cylinder 22 side is selected, and conversely, if it is judged to be small, the heater 24a of the nozzle portion 25 is selected. The size may be judged based on, for example, a threshold value that is set empirically or theoretically. In other words, only the heater located on the tip side of the cylinder 22 is subject to judgment.

[0065] The control device 10 of the injection molding machine 1 according to the third embodiment described above has the following advantages. In this embodiment, the melted state determination unit 15 determines the melted state of the resin inside the cylinder 22 based on the calculation results of the heater heat transfer amount calculation unit 14, which targets the heater 24a or heater 24b located on the tip side of the cylinder 22. As a result, the heat transfer amount is calculated based on the heater 24a or heater 24b located on the tip side of the cylinder 22, so the melted state of the metered resin can be grasped and the user can appropriately and accurately adjust the molding conditions to prevent molding defects and damage to parts.

[0066] [Fourth Embodiment] The control device 10 according to the fourth embodiment has a common configuration with the control device 10 of the injection molding machine 1 according to the first embodiment. In the fourth embodiment, the melted state determination unit 15 determines the melted state based on a threshold value for the calculation result of the heater heat transfer amount calculation unit 14. The threshold value is set to determine the relationship between the resin temperature and the input set temperature. For example, if the heat transfer amount of the heaters 24a to 24d is zero or close to zero, the resin temperature is close to the set temperature. Furthermore, if the heat transfer amount is large, the resin temperature is lower than the set temperature. Conversely, if the heat transfer amount is small, the resin temperature is higher than the set temperature. Therefore, by appropriately setting the threshold value for the heat transfer amount, the resin state can be determined.

[0067] 12 is a diagram illustrating threshold values ​​for determining the relationship between the resin temperature and the set temperature set in the control device 10. The horizontal axis in FIG. 12 represents the amount of heat transfer P Ｔｉ In the fourth embodiment, in order to determine the relationship between the resin temperature and the set temperature, a first threshold value is set as a predetermined upper limit value in the positive direction from 0 as a base, and a second threshold value is set as a predetermined upper limit value in the negative direction from 0 as a base. The first threshold value is set empirically or theoretically as a numerical value at which it can be determined that the resin temperature is below the set temperature. The second threshold value is set empirically or theoretically as a numerical value at which it can be determined that the resin temperature is above the set temperature. The first threshold value and the second threshold value are stored, for example, in a memory unit (not shown) of the control device 10, and read out by the melted state determination unit 15.

[0068] The melting state determination unit 15 of the fourth embodiment determines the heat transfer amount P Ｔｉ is between the first threshold value and the second threshold value, the melting state determination unit 15 determines that the resin temperature is equal to or approximately equal to the set temperature. Ｔｉ is lower than the second threshold value, it is determined that the resin temperature is higher than the set temperature. Ｔｉ If the value is greater than the first threshold value, it is determined that the resin temperature is lower than the set temperature.

[0069] The output unit 20 outputs the determination result derived by the melted state determination unit 15. For example, when it is determined that the resin temperature is lower than the set temperature, the output unit 20 outputs "The resin temperature is lower than the set temperature" to the display device 6. When it is determined that the resin temperature is higher than the set temperature, the output unit 20 outputs "The resin temperature is high" to the display device 6. When it is determined that the resin temperature is equal to the set temperature, the output unit 20 may display information such as "The resin temperature is equal to the set temperature" on the display device 6. The output unit 20 may also display on the display device 6 the diagram shown in FIG. 12 or an image of the diagram shown in FIG. 12 with a symbol indicating a position corresponding to the current calculation result.

[0070] In the fourth embodiment, two thresholds, a first threshold and a second threshold, are set, and three judgment results are set, but this is not limited to this. For example, a configuration may be adopted in which one threshold is used to judge whether the resin temperature is high or low. Also, a configuration may be adopted in which three or more thresholds are set to judge the melting state in more detail.

[0071] The control device 10 of the injection molding machine 1 according to the fourth embodiment described above has the following advantages. In this embodiment, the melted state determination unit 15 determines the melted state based on a threshold value, which is a criterion for determining the relationship between the resin temperature and the input set temperature, and the calculation result of the heater heat transfer amount calculation unit 14. This allows the user to understand the relationship between the resin temperature and the set temperature during molding, making it even easier to understand the melted state of the resin.

[0072] Fifth Embodiment The control device 10 according to the fifth embodiment has the same configuration as the control device 10 of the injection molding machine 1 according to the first embodiment. In the fifth embodiment, the melted state determination unit 15 determines the melted state based on a threshold value for the calculation result of the heater heat transfer amount calculation unit 14. The threshold value is set to determine whether the resin temperature deviates too much from the input set temperature. For example, if the heat transfer amount of the heaters 24a to 24d is too large, the resin temperature will be lower than the normal range. Conversely, if the heat transfer amount is too small, the resin temperature will be higher than the normal range. If the heat transfer amount is outside the normal range, it cannot be said that appropriate molding conditions are being maintained.

[0073] 13 is a diagram illustrating a threshold value for determining the deviation of the resin temperature set in the control device from the set temperature. The horizontal axis in FIG. 13 represents the amount of heat transfer P Ｔｉ In the fifth embodiment, in order to determine whether the resin temperature is within the normal range, a first threshold value is set as a predetermined upper limit value in the positive direction from 0, and a second threshold value is set as a predetermined upper limit value in the negative direction from 0. The first threshold value and the second threshold value are set empirically or theoretically as values ​​that can determine the normal range. The first threshold value and the second threshold value are stored, for example, in a memory unit (not shown) of the control device 10, and are read out by the melted state determination unit 15.

[0074] The melting state determination unit 15 of the fifth embodiment determines the heat transfer amount P Ｔｉ is between the first threshold value and the second threshold value, the melted state determination unit 15 determines that the resin temperature is within the normal range. Ｔｉ is lower than the second threshold value, it is determined that the resin temperature is significantly higher than the set temperature. Ｔｉ If the value is greater than the first threshold value, it is determined that the resin temperature is significantly lower than the set temperature and deviates from it.

[0075] The output unit 20 outputs the determination result derived by the melted state determination unit 15. For example, if the resin temperature is outside the lower limit of the normal range, the output unit 20 outputs warning information such as "The resin temperature is too low compared to the set temperature" to the display device 6. If the resin temperature is outside the upper limit of the normal range, the output unit 20 outputs warning information such as "The resin temperature is too high" to the display device 6. If the resin temperature is within the normal range, the output unit 20 may output information such as "The resin temperature is normal" to the display device 6. The output unit 20 may also display on the display device 6 the diagram shown in FIG. 13 or an image of the diagram shown in FIG. 13 with a symbol indicating the position corresponding to the current calculation result added.

[0076] In the description of the fifth embodiment, two thresholds, the first threshold and the second threshold, are provided, and three determination results are provided, but this is not limited to this. For example, one threshold may be provided, or three or more thresholds may be provided to determine the melting state in more detail.

[0077] The control device 10 of the injection molding machine 1 according to the fifth embodiment described above has the following advantages. In this embodiment, the melted state determination unit 15 determines the melted state based on a threshold value, which is a criterion for determining whether the resin temperature deviates too much from the set temperature, and the calculation result of the heater heat transfer amount calculation unit 14, and the output unit outputs a warning if it is determined that the resin temperature deviates too much from the set temperature. This allows the user to quickly and easily determine whether the melted state of the resin has become inappropriate, and if so, to change the molding conditions to more appropriate metering conditions.

[0078] Sixth Embodiment The control device 10 according to the sixth embodiment has the same configuration as the control device 10 of the injection molding machine 1 according to the first embodiment. In the sixth embodiment, the melted state determination unit 15 compares the results of the heater heat transfer amount calculation unit 14 in different calculation intervals to determine how the resin temperature has changed. In the following description, the calculation interval is determined by the number of shots.

[0079] The melting state determination unit 15 compares the heat transfer amounts calculated by the heater heat transfer amount calculation unit 14 for each interval and calculates the difference between them. Based on this difference in heat transfer amount for each interval and a preset threshold, the melting state determination unit 15 determines whether the resin temperature has changed in different calculation intervals, such as "no change," "temperature increase," or "temperature decrease." The threshold is set, for example, theoretically or empirically, and is a criterion for determining whether a change has occurred. The threshold is stored in a memory unit (not shown) of the control device 10.

[0080] Figure 14 is a graph showing changes in the amount of heat transfer for each calculation interval. In the graph of Figure 14, the horizontal axis represents the number of shots, and the vertical axis represents the amount of heat transfer. In this example, the average value of the amount of heat transfer in interval 1 is A, the average value of the amount of heat transfer in interval 2 is B, and the average value of the amount of heat transfer in interval 3 is C. A, B, and C are numerical values, with a magnitude relationship of A > C > B. Note that the average value here is, for example, a representative value of the amount of heat transfer for each shot in the same calculation interval.

[0081] In the example of Fig. 14, a change in resin temperature is determined in Section 2 and Section 3. For Section 2, A > B, which indicates a difference in the degree of change, is established, so the melted state determination unit 15 determines the melted state to be in a "temperature rise" state, indicating that the resin temperature is higher than in Section 1. For Section 3, C < B, which indicates a difference in the degree of change, is established, so the melted state determination unit 15 determines the melted state to be in a "temperature fall" state, indicating that the resin temperature is lower than in Section 2.

[0082] The output unit 20 outputs the determination result derived by the melted state determination unit 15. For example, if it is determined that the resin temperature is rising, the output unit 20 outputs information indicating "temperature rise" to the display device 6. Furthermore, if it is determined that the resin temperature is falling, the output unit 20 outputs information indicating "temperature fall" to the display device 6. Furthermore, if it is determined that the resin temperature does not exceed the threshold value and there is no change, the output unit 20 may output information such as "no change" to the display device 6. Furthermore, the output unit 20 may cause the display device 6 to display the graph shown in FIG. 14 and information indicating the calculation results.

[0083] In the sixth embodiment, one of three types of determination results is selected, but the present invention is not limited to this. For example, it may be possible to determine whether a temperature change is occurring, or to set multiple thresholds and select one of four or more types of determination results.

[0084] The control device 10 of the injection molding machine 1 according to the sixth embodiment described above has the following advantages. In this embodiment, the melted state determination unit 15 compares the calculation results of the heater heat transfer amount calculation unit 14 in different calculation intervals and determines the change in resin temperature in the calculation interval based on the comparison results. This allows the user to easily grasp the change in resin temperature when conditions such as molding conditions or molding state change, and enables effective adjustment of molding conditions.

[0085] [Seventh embodiment] The control device 10 according to the seventh embodiment has a common configuration with the control device 10 of the injection molding machine 1 according to the first embodiment. In the seventh embodiment, the melted state determination unit 15 utilizes the correlation between the heat transfer amounts of the heaters 24a to 24d, which are acquired in advance, and the deviation of the resin temperature from the set temperature, and converts the heat transfer amounts, which are the calculation results of the heater heat transfer amount calculation unit 14, into the deviation (relative value) between the resin temperature and the set temperature.

[0086] Fig. 15 is a graph showing the relationship between the heat transfer amount of heaters 24a to 24d and the deviation between the resin temperature and the set temperature. In the graph of Fig. 15, the horizontal axis represents the heat transfer amount of the heater, and the vertical axis represents the degree of deviation between the resin temperature and the set temperature. As shown in Fig. 15, a regression equation showing the relationship between the heat transfer amount and the deviation between the resin temperature and the set temperature is derived in advance, and the regression equation is stored in a memory unit (not shown) of control device 10, etc.

[0087] The melting state determination unit 15 substitutes the heat transfer amount into a preset regression equation to calculate the degree of deviation between the resin temperature and the set temperature. The melting state determination unit 15 may also convert the set temperatures of the heaters 24a to 24d into absolute values ​​of the resin temperature.

[0088] The output unit 20 outputs the determination result derived by the melted state determination unit 15. For example, the output unit 20 outputs a numerical value indicating the degree of deviation between the resin temperature and the set temperature, or a resin temperature based on the degree of deviation, as the determination result of the melted state determination unit 15. The output unit 20 may also cause the display device 6 to display the graph and regression equation shown in FIG. 15 together with information indicating the calculation result.

[0089] The control device 10 of the injection molding machine 1 according to the seventh embodiment described above has the following advantages. In this embodiment, the melted state determination unit 15 outputs, as a determination result, at least one of the deviation amount between the resin temperature and the set temperature or the resin temperature (absolute value) calculated based on the deviation amount, based on a regression equation that derives the degree of deviation between the resin temperature and the set temperature in advance and the calculation result of the heater heat transfer amount calculation unit. This allows the user to quantitatively grasp the melted state of the resin.

[0090] Eighth Embodiment The control device 10 according to the eighth embodiment has the same configuration as the control device 10 of the injection molding machine 1 according to the first embodiment. In the eighth embodiment, the method of calculating the heat transfer amount by the heater heat transfer amount calculation unit 14 is different from that in the first embodiment.

[0091] In the eighth embodiment, the operation information acquisition unit 11 acquires the set temperature of each control point of the cylinder 22 as operation information. Alternatively, the actual measured temperature at each control point may be acquired. Furthermore, the characteristic information acquisition unit 12 acquires a preset regression equation along with the capacity of the heaters 24a to 24d as characteristic information. The regression equation is acquired, for example, from a storage unit (not shown) of the control device 10.

[0092] The heater heat transfer amount calculation unit 14 calculates the amount of heat generated by the heaters 24a to 24d to maintain the cylinder 22 at the set temperature without using the calculation results of the heater heat generation amount calculation unit 13. The amount of heat generated in the molding stopped state is the amount of heat required to maintain the cylinder 22 at the set temperature. Therefore, the amount of heat generated in the molding stopped state can be uniquely determined by the set temperature of the control point of the cylinder 22 in the molding stopped state.

[0093] In the eighth embodiment, the heat transfer amount is estimated using a regression equation that shows the relationship between the set temperature of the cylinder 22 and the heat generation amount, which is obtained in advance. This eliminates the need to actually measure the heat transfer amount each time the set temperature of the cylinder 22 changes. Note that, because heat transfer occurs in the axial direction when the set temperatures of adjacent heaters 24a to 24d are different, it is desirable to use the values ​​of not only the target heater but also the adjacent heaters as explanatory variables in the regression equation. Furthermore, in the eighth embodiment, the ambient temperature around the cylinder 22 may also be added as an explanatory variable.

[0094] Ninth Embodiment The control device 10 according to the ninth embodiment has a common configuration with the control device 10a of the injection molding machine 1 according to the second embodiment. In the ninth embodiment, the method of calculating the heat transfer amount by the heater heat transfer amount calculation unit 14 is different from that in the first embodiment.

[0095] In the ninth embodiment, the operation information acquisition unit 11 acquires the set temperature of each control point of the cylinder 22 as operation information. Alternatively, the actual measured temperature at each control point may be acquired. Furthermore, the characteristic information acquisition unit 12 acquires a preset regression equation along with the capacity of the heaters 24a to 24d as characteristic information. The regression equation is acquired, for example, from a storage unit (not shown) of the control device 10.

[0096] The surface temperatures of the heaters 24a to 24d in the molding stopped state are uniquely determined by the set temperature of the cylinder. Therefore, in the ninth embodiment, the surface temperatures of the heaters 24a to 24d are estimated based on a regression equation that shows the relationship between the temperature of the cylinder 22 and the surface temperatures of the heaters 24a to 24d, and the heat dissipation amount in the molding stopped state is calculated. This eliminates the need to actually measure the heat dissipation amount each time the set temperature of the cylinder 22 changes. The ambient temperature around the cylinder may be added as an explanatory variable of the regression equation.

[0097] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0098] The following supplementary notes are further disclosed regarding the above-described embodiment and modified examples. (Supplementary Note 1) A control device (10, 10a) for an 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), comprising: an operation information acquisition unit (11) that acquires operation information related to the operation of the heaters (24a to 24d), a characteristic information acquisition unit (12) that acquires characteristic information related to the characteristics of the injection molding machine (1), and 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. The control device (10, 10a) for an injection molding machine (1) includes: a heater heat transfer amount calculation unit (14) that calculates an amount of heat transfer from the heaters (24a to 24d) to a resin based on the heat generation amount of the heaters (24a to 24d) when molding is performed with the cylinder (22) maintained at a predetermined set temperature, and the heat generation amount of the heaters (24a to 24d) when molding is stopped with the cylinder (22) maintained at a predetermined set temperature; a molten state determination unit (15) that determines the molten state of the resin inside the cylinder based on the calculation result of the heater heat transfer amount calculation unit (14); and an output unit (20) that outputs the determination result of the molten state determination unit (15).

[0099] (Supplementary Note 2) The control device (10, 10a) of the injection molding machine (1) further comprises a heater heat dissipation amount calculation unit (17) that calculates the heat dissipation amount of the heaters (24a to 24d) based on the operation information and the characteristic information, and 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) and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit (17) when the molding is performed, and the heat generation amounts of the heaters (24a to 24d) and the heat dissipation amount calculated by the heater heat dissipation amount calculation unit (17) when the molding is stopped.

[0100] (Note 3) In the control device (10, 10a) of the injection molding machine (1), the melted state determination unit (15) determines the melted state of the resin inside the cylinder based on the calculation result of the heater heat transfer amount calculation unit (14), which calculates the heaters (24a to 24d) located at the tip side of the cylinder (22).

[0101] (Note 4) In the control device (10, 10a) of the injection molding machine (1), the melted state determination unit (15) determines the melted state based on a threshold value, which is a criterion for determining the relationship between the resin temperature and the input set temperature, and the calculation result of the heater heat transfer amount calculation unit (14).

[0102] (Supplementary Note 5) In the control device (10, 10a) of the injection molding machine (1), the melted state determination unit (15) determines the melted state based on a threshold value that is a criterion for determining whether or not the resin temperature has deviated too much from the set temperature and the calculation result of the heater heat transfer amount calculation unit (14), and the output unit (20) outputs warning information when it is determined that the resin temperature has deviated too much from the set temperature.

[0103] (Note 6) In the control device (10, 10a) of the injection molding machine (1), the melted state determination unit (15) compares the calculation results of the heater heat transfer amount calculation unit (14) in different calculation intervals, and determines the change in resin temperature in the calculation interval based on the comparison result.

[0104] (Supplementary Note 7) In the control device (10, 10a) of the injection molding machine (1), the melted state determination unit (15) outputs, as a determination result, at least one of the deviation amount between the resin temperature and the set temperature or the resin temperature calculated based on the deviation amount, based on a regression equation that derives the degree of deviation between the resin temperature and the set temperature in advance and the calculation result of the heater heat transfer amount calculation unit (14).

[0105] REFERENCE SIGNS LIST 1 injection molding machine 10, 10a control device 11 operation information acquisition unit 12 characteristic information acquisition unit 13 heater heat generation amount calculation unit 14 heater heat transfer amount calculation unit 15 melted state determination unit 17 heater heat radiation amount calculation unit 20 output unit

Claims

1. A control device for an injection molding machine, comprising a cylinder, a heater disposed around the cylinder, and a screw disposed inside the cylinder, an operation information acquisition unit that acquires operation information regarding the operation of the heater, a characteristic information acquisition unit that acquires characteristic information regarding 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 cylinder is maintained at a predetermined set temperature and the heat generation amount of the heater during molding stop in a state where the cylinder is maintained at the predetermined set temperature, a melting state determination unit that determines the melting state of the resin inside the cylinder based on the calculation result of the heater heat transfer amount calculation unit, an output unit that outputs the determination result of the melting state determination unit, A control device for an injection molding machine comprising the above.

2. further comprising 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, wherein 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, The control device for an injection molding machine according to claim 1.

3. wherein the melting state determination unit determines the melting state of the resin inside the cylinder based on the calculation result of the heater heat transfer amount calculation unit, with the heater located on the tip side of the cylinder as the calculation target, The control device for an injection molding machine according to claim 1 or 2.

4. wherein the melting state determination unit determines the melting state based on a threshold value that is a criterion for determining the relationship between the resin temperature and the input set temperature and the calculation result of the heater heat transfer amount calculation unit, The control device for an injection molding machine according to claim 1 or 2.

5. wherein the melting state determination unit determines the melting state based on a threshold value that is a criterion for determining whether the resin temperature deviates too much from the set temperature and the calculation result of the heater heat transfer amount calculation unit, and when it is determined that the resin temperature deviates too much from the set temperature, the output unit outputs warning information, The control device for an injection molding machine according to claim 1 or 2.

6. wherein the melting state determination unit Compare the calculation results of the heater heat transfer amount calculation unit in different calculation intervals, and determine the change in the resin temperature in the calculation interval based on the comparison result. The control device for an injection molding machine according to claim 1 or 2.

7. The molten state determination unit Based on a regression formula for deriving the degree of deviation between the resin temperature and the set temperature in advance and the calculation result of the heater heat transfer amount calculation unit, output at least one of the deviation amount between the resin temperature and the set temperature or the resin temperature calculated based on the deviation amount as a determination result. The control device for an injection molding machine according to claim 1 or 2.