WO2024100763A1

WO2024100763A1 - Control device for injection-molding machine

Info

Publication number: WO2024100763A1
Application number: PCT/JP2022/041550
Authority: WO
Inventors: 京祐中村
Original assignee: ファナック株式会社
Priority date: 2022-11-08
Filing date: 2022-11-08
Publication date: 2024-05-16

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

This disclosure relates to a control device for an injection molding machine.

　Conventionally, in a control device for an injection molding machine, the amount of heat and temperature are estimated in a technique for controlling heater output so as to maintain the control point temperature of a cylinder at a set temperature. (See, for example,

Patent Documents

1, 2, and 3.)

International Publication No. 2008/149742 International Publication No. 2019/177040 JP 2010-241034 A

Even if the heater output is controlled to maintain the control point temperature at the set temperature, the actual resin temperature may differ from the set temperature when it is measured. For example, under conditions where there is an insufficient supply of heat to the resin, the resin temperature may fall far below the set temperature, and conversely, under conditions where there is too much heat, the resin temperature may far exceed the set temperature. When the resin temperature deviates significantly from the set temperature, there is a high possibility of molding defects or damage to parts such as screws and cylinders.

From the standpoint of accuracy, it is preferable to directly control the resin temperature inside the cylinder rather than the control point temperature, but directly measuring and controlling the temperature of the molten resin requires meeting strict conditions such as cylinder strength, sensor strength, and cost. However, when a user sees 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 is at the set temperature. Conventional technology left room for improvement in terms of allowing users to properly grasp the molten state (temperature) of the resin.

This disclosure has been made in consideration of the above problems, and aims to provide a technology that allows users to properly understand the molten state of resin in an injection molding machine and effectively reduce molding defects.

The present disclosure relates to a control device for an injection molding machine that includes a cylinder, a heater disposed around the cylinder, and a screw disposed 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 the 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 a 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.

This disclosure provides a technology that allows users to properly understand the molten state of resin in an injection molding machine and effectively reduces molding defects.

1 is a schematic diagram showing a configuration of an injection molding machine according to a first embodiment. FIG. FIG. 2 is a perspective view showing a heater disposed in the cylinder according to the first embodiment. FIG. 2 is a functional block diagram of a control device for the injection molding machine according to the first embodiment. FIG. 4 is a schematic diagram illustrating a heat balance during forming according to the first embodiment. FIG. 4 is a schematic diagram illustrating a heat balance when molding is stopped in the first embodiment. 4 is a flowchart showing an example of a processing flow by a control device of the injection molding machine according to the first embodiment. FIG. 11 is a schematic diagram illustrating a heat balance during forming according to the second embodiment. FIG. 11 is a schematic diagram illustrating the heat balance when molding is stopped in the second embodiment. FIG. 11 is a functional block diagram of a control device for an injection molding machine according to a second embodiment. 10 is a flowchart showing an example of a processing flow by a control device of an injection molding machine according to a second embodiment. 11 is a graph showing the relationship between the amount of heat transfer of a measured resin and the deviation between the resin temperature and a set temperature. 11 is a diagram illustrating a threshold value for determining a relationship between a resin temperature and a set temperature set in the control device. FIG. 11 is a diagram illustrating a threshold value for determining the degree of deviation of a resin temperature set in a control device from a set temperature. FIG. 13 is a graph showing changes in the amount of heat transfer for each calculation interval. 11 is a graph showing the relationship between the amount of heat transfer of a heater and the deviation between the resin temperature and the set temperature.

The embodiments of the present disclosure will be described in detail below with reference to the drawings. In the description of the second and subsequent embodiments, the same reference numerals will be used to designate configurations common to the first embodiment, and descriptions thereof will be omitted as appropriate.

[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 section 2, a mold clamping section 3, a control device 10, and a display device 6.

The injection unit 2 is an injection device that includes 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 rotating. The cooling jacket 26 is a device that cools the inside of the cylinder 22 (for example, the part on the root side inside the cylinder 22), and cooling water circulates through it.

As shown in FIG. 2, heaters 24a to 24d are arranged, for example, in a plurality of positions along the axial direction of cylinder 22. Specifically, heaters 24a to 24d are arranged in a plurality of positions from nozzle portion 25 at the axial tip of cylinder 22 to the base end. Note that there is no particular limit to the number of heaters 24a to 24d.

In this embodiment, four heaters 24a to 24d are arranged along the axial direction 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.

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

The mold clamping unit 3 is a device that clamps the mold 5. A molded product is formed by clamping the mold 5 with the mold clamping unit 3.

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 equipped with memories such as a ROM (read only memory) and a RAM (random access memory), a CPU (control processing unit), and a communication control unit, which are connected to each other via a bus, for example. The functions and operations of each functional unit of the control device 10 described below are achieved by the cooperation of the CPU and memory mounted on the computer, and the control program stored in the memory.

The control device 10 has, 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 melting state determination unit 15, and an output unit 20.

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, for example, indicated as 0 to 100%. The operation rate is determined, for example, based on the output, such as the voltage, of the heaters 24a to 24d.

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.

The heater heat generation amount calculation unit 13 calculates the heat generation amount of the heaters 24a to 24d based on the acquired operation information and characteristic information. The heater heat generation amount calculation unit 13 calculates the heat generation amount per unit time of each heater 24a to 24d in a state in which the cylinder 22 is maintained at a preset temperature, for example. 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.

An example of a method for calculating the amount of heat generated by the heater heat generation amount calculation unit 13 will be described below. The amount of heat generated can be calculated, for example, by the following formula (1). In formula (1), P _Hi represents the amount of heat generated per unit time, t ₁ represents the calculation start time, t ₂ represents the calculation end time, W _i represents the heater capacity, and r _i represents the heater operation rate.

The heater heat transfer amount calculation unit 14 calculates the amount of heat transfer from each of the heaters 24a to 24d to the resin based on the calculation result of the heater heat transfer 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 transfer per unit time from the heaters 24a to 24d to the resin is P _Ti . In a state where the cylinder 22 is maintained at a predetermined set temperature, if the amount of heat generated per unit time when molding is being performed is P _Hi and the amount of heat generated per unit time when molding is stopped is P' _Hi , the amount of heat transfer is expressed by the following formula (2). As shown in the following formula (2), the amount of heat transfer P _Ti can be calculated from the difference between the amount of heat generated when molding is being performed P _Hi and the amount of heat generated when molding is stopped P' _Hi .

The formula (2) will be described 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 _Hi during molding to maintain the cylinder 22 at the set temperature can be considered as the sum of the heat transfer amount P _Ti and various heat dissipation. Here, the various heat dissipation is the sum of the heat amount applied to the heater 24b, the heat transfer amount to the front (the nozzle portion 25 side), the heat transfer amount to the rear (the opposite side of the nozzle portion 25), and the heat dissipation from the surface of the heater 24b.

On the other hand, when considering the heat balance when molding is stopped, unlike when molding is in progress, the screw 23 stops inside the cylinder 22 and the resin does not flow, resulting in a stagnant state. In this state, the resin temperature can be considered to be the same as the temperature of the cylinder 22, so the heat generated by the heater 24b is not transferred to the resin. Therefore, as shown in Fig. 5, the heat generation amount _P'Hi when molding is stopped and the cylinder 22 is maintained at the set temperature can be considered to be equal to the various heat dissipations. Since the various heat dissipations can be considered to be the same as when molding is in progress, the heat transfer amount _PTi can be obtained by subtracting the heat generation amount _P'Hi from the heat generation amount _PHi , which cancels out the various heat dissipations.

Next, returning to FIG. 3, the melting state determination unit 15 will be described. The melting state determination unit 15 determines the melting state of the resin inside the cylinder 22 based on the calculation results of the heater heat transfer amount calculation unit 14.

The amount of heat transfer P _Ti from the heaters 24a to 24d to the resin 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 transport direction, the resin sent to that zone will be at a lower temperature 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 amount of heat transfer P _Ti is large. Conversely, if the resin receives an excessive amount of heat upstream of a certain heater zone in the resin transport direction, the resin sent to that zone will be at a higher temperature than the set temperature of the heaters 24a to 24d, so the amount of heat transfer P _Ti is small. In other words, there is a negative correlation between the "deviation of the resin temperature from the set temperature of each heater 24a to 24d" and the "amount of heat transfer P _Ti ."

The melting state determination unit 15 of this embodiment calculates the melting state of the resin as the degree of deviation from the heater set temperature by utilizing the correlation between "the deviation of the resin temperature from the set temperature of each heater 24a to 24d" and "the amount of heat transfer P _Ti ."

The output unit 20 will now be described. The output unit 20 outputs the result of the melting state judgment made by the melting state judgment unit 15 to enable the user to grasp the melting state. In this embodiment, the output unit 20 executes a process to display the result of the judgment made by the melting state judgment unit 15 on the display device 6 of the injection molding machine 1. The output unit 20 may be configured to output the result of the judgment made by the melting state judgment 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.

The display device 6 is, for example, an output device such as a liquid crystal display or a touch panel display. Note that instead of the display device 6, the determination result of the melting state determination unit 15 may be output by a sound output device that outputs sound.

Next, a process flow for calculating the amount of heat transfer _PTi will be described with reference to Fig. 6. Fig. 6 is a flow chart showing an example of a process flow by the control device 10 of the injection molding machine 1 according to the first embodiment.

When the process for calculating the amount of heat transfer P _Ti 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 operating rates related to the operations of the heaters 24 a to 24 d 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.

The heater heat generation amount calculation unit 13 calculates the heat generation amount 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 amount per unit time of each 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 rate of the heaters 24a to 24d and the capacity of the heaters 24a to 24d.

Next, the heater heat transfer amount calculation unit 14 calculates the amount of heat transfer from the heaters 24a to 24d to the resin (step S13). The heater heat transfer amount calculation unit 14, for example, substitutes the heat generation amount P _Hi of the heaters 24a to 24d when molding is being performed and the heat generation amount P' _Hi of the heaters 24a to 24d when molding is stopped into the above formula (2) to calculate the heat transfer amount P _Ti from the heaters 24a to 24d to the resin.

Next, the melted state determination unit 15 determines the melted state based on the heat transfer amount P _Ti , which is the calculation result of the heater heat transfer amount calculation unit 14 (step S14). The melted state determination unit 15 outputs information indicating the degree of the melted state based on a preset condition, for example, by utilizing a negative correlation between "the deviation of the resin temperature from the set temperature of each heater 24a to 24d" and "the heat transfer amount P _Ti ". The information indicating the degree of the melted state may be a numerical value, or may be a character, symbol, graph, picture, or a combination thereof, which indicates a state corresponding to the numerical value.

When the molten state determination unit 15 outputs the determination result, the output unit 20 outputs the determination result (step S15). The output unit 20 executes a process to display, for example, the determination result by the molten state determination unit 15 on the display device 6, which may be a numerical value, a letter, a symbol, a graph, a picture, or a combination thereof.

After the processing by the output unit 20 in step S15, if the molding process is to be continued, the control device 10 returns the process 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 been stopped, it executes a process to stop 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, the user's operation or whether the molten state satisfies a predetermined condition.

The control device 10 of the injection molding machine 1 according to the first embodiment described above provides the following effects. That is, the injection molding machine 1 includes a cylinder 22, heaters 24a to 24d arranged around the cylinder 22, and a screw 23 disposed inside the cylinder 22. The control device 10 of the injection molding machine 1 includes 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 in a state in which the cylinder 22 is maintained at a predetermined set temperature and the heat generation amounts of the heaters 24a to 24d when molding is stopped in a state in which the cylinder 22 is 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 special sensors. Being able to grasp the melting state makes it possible to know whether the molding conditions are good or bad, and to appropriately adjust the molding conditions. 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 parts.

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

Even if 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 rates of the heaters 24a to 24d differ, the surface temperatures of the heaters 24a to 24d differ, and the amount of heat dissipated from the surfaces of the heaters 24a to 24d also differ. For example, the amount of heat dissipated per unit time P _Ri during molding as shown in FIG. 7 differs from the amount of heat dissipated per unit time P' _Ri during molding is stopped as shown in FIG. 8 (amount of heat dissipated P _Ri ≠ amount of heat dissipated P' _Ri ). Therefore, if the difference between the amount of heat dissipated by the heaters 24a to 24d during molding and when molding is stopped is corrected, the amount of heat transfer can be calculated more accurately.

The heat generation amount P _Hi during molding can be considered as the sum of the heat transfer amount P _Ti , the heat radiation amount P _Ri , and other heat radiation excluding the heat radiation amount P _Ri from various heat radiation. 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).

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 adding them together. 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 detection value of a temperature sensor (not shown) or by estimating using a predetermined function.

An example of a method for calculating the amount of heat dissipation will be described. The amount of heater convection heat dissipation can be calculated, for example, using the following formula (3). The amount of heater radiation heat dissipation can be calculated, for example, using the following formula (4). In the formula, P _rci represents the amount of heater convection heat dissipation, T _Hi represents the heater surface temperature, T _C represents the ambient temperature, A _i represents the heater surface area, h represents the heat transfer coefficient, P _Rri represents the amount of heater radiation heat dissipation, ε represents the emissivity, and σ represents the Stefan-Boltzmann coefficient.

It is considered that the amount of heat transfer from a heater 24 to adjacent zones such as the front or rear 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 transfer to the zone of heater 24a and the zone of heater 24c adjacent to the zone of heater 24b does not change. Therefore, it can be considered that the other heat dissipation excluding P _Ri from the various heat dissipation during molding is equal to the other heat dissipation excluding P' _Ri from the various heat dissipation during molding stop. In the second embodiment, the heat transfer amount is calculated using the following formula (5).

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 processing flow by the control device 10a of the injection molding machine 1 according to the second embodiment.

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 in the process for calculating the heat transfer amount _PTi , but the other configurations are common to the first embodiment.

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

In addition, the operation information acquisition 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). Constants related to heat dissipation include, for example, the heat transfer coefficient, the emissivity, the Stefan-Boltzmann coefficient, etc.

Furthermore, similar 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).

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

After the heater heat radiation amount calculation unit 17 calculates the heat radiation amount, the heater heat transfer amount calculation unit 14 calculates the heat transfer amount P _Ti from the heaters 24a to 24d to the resin (step S24). The heater heat transfer amount calculation unit 14 calculates the heat transfer amount P Ti from the heaters 24a to 24d to the resin by substituting, for example, the heat generation amount P _Hi and the heat radiation amount P _Ri of the heaters 24a to 24d when molding is being performed, and the heat generation amount P' _Hi and the heat radiation amount P' _Ri of the heaters 24a to 24d when molding is stopped, into the above formula ( ₅ ).

The melted state determination unit 15 determines the melted state based on the heat transfer amount _PTi calculated by the heater heat transfer amount calculation unit 14 (step S25), and the output unit 20 performs output processing based on the determination result of the melted state determination unit 15 (step S26). The processing of step S27 is the same as the processing of step S16 in FIG. 6.

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

The control device 10a of the injection molding machine 1 according to this embodiment further includes a heater heat dissipation calculation unit 17 that calculates the amount of heat dissipation of the heaters 24a to 24d based on the operation information and characteristic information, and the heater heat transfer calculation unit 14 calculates the amount of heat transfer from the heaters 24a to 24d to the resin based on the amounts of heat generated by the heaters 24a to 24d and the amount of heat dissipation calculated by the heater heat transfer calculation unit 17 when molding is in progress, and the amounts of heat generated by the heaters 24a to 24d and the amount of heat dissipation calculated by the heater heat transfer calculation unit 17 when molding is stopped. 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 large impact on the calculation of the amount of heat transfer, making it possible to calculate the amount of heat transfer more efficiently and accurately.

[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.

The thing that 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 heater 24b located at the tip side of the cylinder 22.

Figure 11 is a graph showing the relationship between the amount of heat transfer of the measured resin and the deviation between the resin temperature and the set temperature. In the graph of Figure 11, the horizontal axis is the amount of heat transfer of the heater 24b, and the vertical axis is the experimental result showing the degree of deviation between the resin temperature and the set temperature. This experiment was performed using the same molding machine, screw cylinder, and resin material, and various plasticization conditions were changed except for the metering stroke. The approximate straight line in Figure 11 also shows that there is a very strong negative correlation between the amount of heat transfer of the heater 24b and the deviation between the resin temperature and the set temperature. In other words, when the amount of heat transfer is very large, the supply section where the resin is supplied and the compression section where the resin is compressed do not receive a sufficient amount of heat, and resin at a temperature lower than the set temperature is measured, which may lead to deterioration of filling properties and molding defects. In addition, when the resin temperature is low, the viscosity of the resin is high, so a large load is applied to the parts at the tip of the screw 23, which may cause damage. Conversely, if the amount of heat transfer is small, too much heat may be applied, causing the metering resin to become too hot, leading to thermal degradation.

In the third embodiment, therefore, in order to accurately determine the molten state of the metered resin by utilizing this correlation in the metered resin, the object of determination by the molten state determination unit 15 is the heater 24a of the nozzle portion 25 that is closest to the metered resin or the heater 24b on the tip side of the cylinder 22.

The object to be judged may be selected, for example, based on 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, for example, based on 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 judged.

The control device 10 of the injection molding machine 1 according to the third embodiment described above has the following effects. 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 at the tip side of the cylinder 22. As a result, the amount of heat transfer is calculated based on the heater 24a or heater 24b located at 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.

[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, when the heat transfer amount of the heaters 24a to 24d is 0 or close to 0, the resin temperature is close to the set temperature. Also, if the heat transfer amount is large, the resin temperature is lower than the set temperature, and conversely, if the heat transfer amount is small, the resin temperature is higher than the set temperature. Therefore, the state of the resin can be determined by appropriately setting the threshold value for the heat transfer amount.

FIG. 12 is a diagram for explaining the threshold value for determining the relationship between the resin temperature and the set temperature set in the control device 10. The horizontal axis shown in FIG. 12 indicates 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 as a predetermined upper limit value in the + direction with 0 as a reference, and a second threshold value as a predetermined upper limit value in the - direction with 0 as a reference, are set. The first threshold value is empirically or theoretically set as a numerical value by which it can be determined that the resin temperature is below the set temperature. The second threshold value is empirically or theoretically set as a numerical value by which it can be determined that the resin temperature is above the set temperature. The first threshold value and the second threshold value are, for example, stored in a storage unit (not shown) of the control device 10 and read out by the melting state determination unit 15.

The melted state determination unit 15 of the fourth embodiment determines that the resin temperature is equal to or approximately equal to the set temperature when the heat transfer amount P _Ti , which is the calculation result of the heater heat transfer amount calculation unit 14, is between the first threshold value and the second threshold value. The melted state determination unit 15 determines that the resin temperature is higher than the set temperature when the heat transfer amount P _Ti is a numerical value lower than the second threshold value. On the other hand, the melted state determination unit 15 determines that the resin temperature is lower than the set temperature when the heat transfer amount P _Ti is a numerical value higher than the first threshold value.

The output unit 20 outputs the judgment result derived by the melting state judgment unit 15. For example, when the output unit 20 judges that the resin temperature is lower than the set temperature, it outputs "The resin temperature is lower than the set temperature" to the display device 6. When the output unit 20 judges that the resin temperature is higher than the set temperature, it outputs "The resin temperature is high" to the display device 6. When the output unit 20 judges that the resin temperature is equal to the set temperature, it 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 the position corresponding to the current calculation result added.

In the description of 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 a single threshold is set and the resin temperature is judged to be either 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.

The control device 10 of the injection molding machine 1 according to the fourth embodiment described above has the following effects. In this embodiment, the molten state determination unit 15 determines the molten 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 when molding is performed, making it even easier to understand the molten state of the resin.

[Fifth embodiment]
The control device 10 according to the fifth embodiment has a common configuration with 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 is too far from the input set temperature. For example, if the heat transfer amount of the heaters 24a to 24d is too large, the resin temperature is lower than the normal range, and conversely, if the heat transfer amount is too small, the resin temperature is higher than the normal range. If the heat transfer amount is outside the normal range in this way, it cannot be said that appropriate molding conditions are being maintained.

FIG. 13 is a diagram for explaining a threshold value for determining the deviation of the resin temperature set in the control device from the set temperature. The horizontal axis shown in FIG. 13 indicates the amount of heat transfer P _Ti . In the fifth embodiment, in order to determine whether the resin temperature is within the normal range or not, a first threshold value is set as a predetermined upper limit value in the + direction with 0 as a reference, and a second threshold value is set as a predetermined upper limit value in the - direction with 0 as a reference. 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 storage unit (not shown) of the control device 10, and are read out by the melting state determination unit 15.

The melted state determination unit 15 of the fifth embodiment determines that the resin temperature is within the normal range when the heat transfer amount P _Ti , which is the calculation result of the heater heat transfer amount calculation unit 14, is between the first threshold value and the second threshold value. The melted state determination unit 15 determines that the resin temperature is significantly higher than the set temperature and deviates from it when the heat transfer amount P _Ti is a numerical value lower than the second threshold value. On the other hand, the melted state determination unit 15 determines that the resin temperature is significantly lower than the set temperature and deviates from it when the heat transfer amount P _Ti is a numerical value higher than the first threshold value.

The output unit 20 outputs the judgment result derived by the melting state judgment unit 15. For example, if the resin temperature is outside the lower part 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 part 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.

In the description of the fifth 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, one threshold may be set, or three or more thresholds may be set to judge the melting state in more detail.

The control device 10 of the injection molding machine 1 according to the fifth embodiment described above has the following effects. 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, the molding conditions can be changed to more appropriate weighing conditions.

Sixth Embodiment
The control device 10 according to the sixth embodiment has a common configuration with 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 and determines how the resin temperature has changed. In the following description, the calculation interval is determined by the number of shots.

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

FIG. 14 is a graph showing the change in the amount of heat transfer for each calculation interval. In the graph of FIG. 14, the horizontal axis indicates the number of shots, and the vertical axis indicates the amount of heat transfer. In this example, the average amount of heat transfer in interval 1 is A, the average amount of heat transfer in interval 2 is B, and the average 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.

In the example of Figure 14, the 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 molten state determination unit 15 determines the molten 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 molten state determination unit 15 determines the molten state to be in a "temperature fall" state, indicating that the resin temperature is lower than in section 2.

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

In the description of the sixth embodiment, one of three types of judgment results is selected, but this is not limited to the above. For example, it may be determined whether or not a temperature change is occurring, or multiple thresholds may be set to select one of four or more types of judgment results.

The control device 10 of the injection molding machine 1 according to the sixth embodiment described above has the following effects. 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 result. This allows the user to easily grasp the change in resin temperature when conditions such as molding conditions or molding state change, and allows for effective adjustment of molding conditions.

[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 acquired in advance and the deviation of the resin temperature from the set temperature, and converts the heat transfer amount, which is the calculation result of the heater heat transfer amount calculation unit 14, into the deviation (relative value) between the resin temperature and the set temperature.

FIG. 15 is a graph showing the relationship between the amount of heat transfer of heaters 24a-24d and the deviation between the resin temperature and the set temperature. In the graph of FIG. 15, the horizontal axis shows the amount of heat transfer of the heaters, and the vertical axis shows 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 amount of heat transfer, the resin temperature, and the deviation between the set temperature is derived in advance, and the regression equation is stored in a memory unit (not shown) of the control device 10, etc.

The melted state determination unit 15 substitutes the amount of heat transfer into a preset regression equation and calculates the degree of deviation between the resin temperature and the set temperature. The melted state determination unit 15 may also convert the set temperatures of the heaters 24a to 24d into an absolute value for the resin temperature.

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

The control device 10 of the injection molding machine 1 according to the seventh embodiment described above has the following effects. In this embodiment, the melted state determination unit 15 outputs at least one of the amount of deviation between the resin temperature and the set temperature or the resin temperature (absolute value) calculated based on the amount of deviation as a determination result 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.

[Eighth embodiment]
The control device 10 according to the eighth embodiment has a common configuration with 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.

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. The actual temperature at each control point may also be acquired. In addition, the characteristic information acquisition unit 12 acquires a preset regression equation together with the capacity of the heaters 24a to 24d as characteristic information. The regression equation is acquired, for example, from a memory unit (not shown) of the control device 10.

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.

In the eighth embodiment, the amount of heat transfer is estimated using a regression equation that shows the relationship between the set temperature of the cylinder 22 obtained in advance and the amount of heat generated. This eliminates the need to actually measure the amount of heat transfer each time the set temperature of the cylinder 22 changes. Note that when the set temperatures of adjacent heaters 24a to 24d are different, heat moves in the axial direction, so 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.

[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.

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. The actual temperature at each control point may also be acquired. In addition, the characteristic information acquisition unit 12 acquires a preset regression equation together with the capacity of the heaters 24a to 24d as characteristic information. The regression equation is acquired, for example, from a memory unit (not shown) of the control device 10.

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 amount of heat dissipation in the molding stopped state is calculated. This eliminates the need to actually measure the amount of heat dissipation 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.

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 to these embodiments without departing from the gist of the present disclosure, or without departing from the gist of the present disclosure derived from the contents described in the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-mentioned 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 formulas are used to explain the above-mentioned embodiments.

The following supplementary notes are further disclosed regarding the above embodiment and modified examples.
(Appendix 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),
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 relating to characteristics of the injection molding machine (1);
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;
a heater heat transfer amount calculation unit (14) for calculating an amount of heat transfer from the heaters (24a to 24d) to a resin based on the amount of heat generated by the heaters (24a to 24d) during molding 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 to 24d) when molding is stopped in a state in which the cylinder (22) is maintained at a predetermined set temperature;
a melting state determination unit (15) that determines a melting state of the resin inside the cylinder based on a calculation result of the heater heat transfer amount calculation unit (14);
an output unit (20) that outputs a result of the determination by the melting state determination unit (15);
The present invention relates to a control device (10, 10a) for an injection molding machine (1).

(Appendix 2)
The control device (10, 10a) of the injection molding machine (1) further comprises a heater heat radiation amount calculation unit (17) that calculates the heat radiation amount of the heaters (24a to 24d) based on the operation information and the characteristic information,
The heater heat transfer amount calculation unit (14)
The amount of heat transferred from the heaters (24a to 24d) to the resin is calculated based on the amount of heat generated by the heaters (24a to 24d) during molding and the amount of heat dissipation calculated by the heater heat dissipation calculation unit (17), and the amount of heat generated by the heaters (24a to 24d) and the amount of heat dissipation calculated by the heater heat dissipation calculation unit (17) when molding is stopped.

(Appendix 3)
In the control device (10, 10a) of the injection molding machine (1), the melt state determination unit (15)
The melting state of the resin inside the cylinder is determined based on the calculation results of the heater heat transfer amount calculation unit (14), which calculates the heaters (24a to 24d) located on the tip side of the cylinder (22).

(Appendix 4)
In the control device (10, 10a) of the injection molding machine (1), the melt state determination unit (15)
The melting state is judged based on a threshold value, which is a criterion for judging the relationship between the resin temperature and the input set temperature, and the calculation result of the heater heat transfer amount calculation unit (14).

(Appendix 5)
In the control device (10, 10a) of the injection molding machine (1), the melt state determination unit (15)
A melting state is determined based on a threshold value, which is a criterion for determining whether or not the resin temperature is too far from the set temperature, and a calculation result of the heater heat transfer amount calculation unit (14);
The output unit (20) outputs warning information when it is determined that the resin temperature is too far away from the set temperature.

(Appendix 6)
In the control device (10, 10a) of the injection molding machine (1), the melt state determination unit (15)
The calculation results of the heater heat transfer amount calculation unit (14) in different calculation intervals are compared, and a change in the resin temperature in the calculation interval is determined based on the comparison result.

(Appendix 7)
In the control device (10, 10a) of the injection molding machine (1), the melt state determination unit (15)
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), 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 is output as a judgment result.

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

A control device for an injection molding machine including a cylinder, a heater disposed around the cylinder, and a screw disposed inside the cylinder,
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 relating to characteristics of the injection molding machine;
a heater heat generation amount calculation unit that calculates a heat generation amount of the heater based on the acquired operation information and characteristic information;
a heater heat transfer amount calculation unit that calculates an amount of heat transfer from the heater to a resin based on a heat generation amount of the heater when molding is performed in a state where the cylinder is maintained at a predetermined set temperature and a heat generation amount of the heater when molding is stopped in a state where the cylinder is maintained at a predetermined set temperature;
a melting state determination unit that determines a melting state of the resin inside the cylinder based on a calculation result of the heater heat transfer amount calculation unit;
an output unit that outputs a determination result of the melting state determination unit;
A control device for an injection molding machine comprising:
a heater heat dissipation amount calculation unit that calculates a heat dissipation amount of the heater based on the operation information and the characteristic information,
The heater heat transfer amount calculation unit is
a heat transfer amount from the heater to the resin is calculated based on the heat generation amount of the heater and the heat radiation amount calculated by the heater heat radiation amount calculation unit during the molding operation, and the heat generation amount of the heater and the heat radiation amount calculated by the heater heat radiation amount calculation unit during the molding stop time;
The control device for an injection molding machine according to claim 1.
The melting state determination unit is
3. The control device for an injection molding machine according to claim 1, further comprising: a heater disposed at a tip end of the cylinder; a heater heat transfer amount calculation unit that calculates a melting state of the resin inside the cylinder based on a calculation result of the heater heat transfer amount calculation unit.
The melting state determination unit is
A melting state is determined based on a threshold value that is a criterion for determining the relationship between the resin temperature and the input set temperature and a calculation result of the heater heat transfer amount calculation unit.
4. The control device for an injection molding machine according to claim 1.
The melting state determination unit is
determining a melting state based on a threshold value that is a criterion for determining whether or not the resin temperature is too far from the set temperature and a calculation result of the heater heat transfer amount calculation unit;
the output unit outputs warning information when it is determined that the resin temperature is too far from the set temperature.
4. The control device for an injection molding machine according to claim 1.
The melting state determination unit is
comparing the calculation results of the heater heat transfer amount calculation unit in different calculation intervals, and determining a change in the resin temperature in the calculation interval based on the comparison result;
4. The control device for an injection molding machine according to claim 1.
The melting state determination unit is
based on a regression equation for deriving a degree of deviation between the resin temperature and the set temperature in advance and a calculation result of the heater heat transfer amount calculation unit, outputting 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 judgment result;
4. The control device for an injection molding machine according to claim 1.