Injection molding machine, injection device, and control method for injection molding machine

Abstract

This reduces the power consumption associated with nozzle temperature control. [Solution] If the detected temperature of the injection nozzle is lower than the nozzle reference temperature (YES in step S2), the injection molding machine heats the injection nozzle using the detected temperature of the synchronization zone as the target temperature (step S6). Also, if the detected temperature of the injection nozzle is higher than the nozzle reference temperature (NO in step S2), the injection molding machine heats the injection nozzle using the nozzle set temperature as the target temperature.

Description

Technical Field

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

Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-240203 (Patent Document 1) discloses an injection molding machine. This injection molding machine controls the temperature of the nozzle and the temperature of the cylinder by feedback control.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the injection molding machine as described above, generally, the volume of the nozzle is smaller than the volume of the cylinder. Furthermore, since the material for injection is stored in the cylinder, the heat capacity of the cylinder is larger than the heat capacity of the nozzle. Therefore, when the same amount of heat is applied to the nozzle and the cylinder, the temperature rise rate of the nozzle is faster than the temperature rise rate of the cylinder.

[0005]

[0006] ​This invention was made to solve these problems, and its purpose is to suppress the power consumed when heating the nozzle. [Means for solving the problem]

[0007] In the injection molding machine according to this disclosure, the nozzle temperature is controlled so as not to exceed the cylinder temperature, based on the cylinder temperature. [Effects of the Invention]

[0008] According to this disclosure, the power consumed when heating the nozzle can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram illustrating the configuration of the injection molding machine in this embodiment. [Figure 2] This is a diagram illustrating the heating cylinder and injection nozzle. [Figure 3] This is a functional block diagram of the control unit. [Figure 4] This is a flowchart illustrating the main processes performed by the control unit. [Figure 5] This figure shows the simulation results of this embodiment. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. The same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] [Configuration of an injection molding machine] Figure 1 is a diagram illustrating the configuration of the injection molding machine 100 of this embodiment. For the sake of explanation, in Figure 1, the floor surface on which the injection molding machine 100 is placed is defined as the XY plane, and the direction perpendicular to this floor surface is defined as the Z axis direction. The positive direction of the Z axis may be referred to as the upper side or upward, and the negative direction as the lower side or downward. Although the injection molding machine 100 is shown as a horizontal injection molding machine, it is not limited to a horizontal type and may be a vertical injection molding machine.

[0012] The injection molding machine 100 comprises a mold clamping device 110 for clamping the mold, an injection device 120 for melting and injecting the injection material, an operation panel 130, and a control device 140. In Figure 1, the mold clamping device 110 is positioned on the negative side of the X-axis relative to the injection device 120.

[0013] The clamping device 110 includes a bed 111, a fixed platen 112, a clamping housing 113, a movable platen 114, a tie bar 115, a clamping mechanism 116, molds 117 and 118, and a ball screw 119. The bed 111 is positioned on the floor, and the fixed platen 112, clamping housing 113, movable platen 114, and other equipment are mounted on its upper surface.

[0014] The fixed platen 112 is fixed to the end of the bed 111 closest to the injection unit 120 (i.e., in the positive direction of the X-axis). The clamping housing 113 is located at the end of the bed 111 in the negative direction of the X-axis. The fixed platen 112 and the clamping housing 113 are connected by tie bars 115, which include multiple bars. The clamping housing 113 is movable in the X-axis direction on the bed 111.

[0015] The movable platen 114 is positioned on the bed 111 between the fixed platen 112 and the clamping housing 113. The movable platen 114 is configured to move in the X-axis direction. The clamping housing 113 and the movable platen 114 are connected by a clamping mechanism 116. The clamping mechanism 116 has a toggle mechanism. A ball screw 119 is connected to the toggle mechanism, and by driving a servo motor 151 located in the clamping housing 113 to rotate the ball screw 119, the movable platen 114 can be moved relative to the clamping housing 113 in the X-axis direction. Alternatively, a hydraulically driven linear cylinder may be used as the clamping mechanism 116.

[0016] Molds 117 and 118 are positioned on the movable platen 114 and the fixed platen 112, respectively. Molds 117 and 118 are positioned facing each other between the movable platen 114 and the fixed platen 112. By moving mold 117 in the X-axis direction using the mold clamping mechanism 116, molds 117 and 118 can be brought into close contact, or mold 117 can be separated from mold 118. In the following description, the process of transitioning molds 117 and 118 from a separated state to a close contact state will be referred to as "mold clamping". Also, the process of transitioning molds 117 and 118 from a close contact state to a separated state will be referred to as "mold opening".

[0017] In the mold clamping process, molds 117 and 118 are brought into close contact, and molten material (resin) is filled into the mold and cooled to solidify, thereby forming a product (molded product) of the desired shape. After the product is formed, in the mold opening process, mold 117 is separated from mold 118, and the molded product can be removed from mold 117 by operating an ejection mechanism (not shown) located on the movable platen 114. The ejection mechanism is driven by a servo motor 152 located on the movable platen 114. The process of removing the product using the ejection mechanism is called the "ejection" process.

[0018] The injection device 120 includes a base 121, a heating cylinder 122, an operating device 124, a hopper 125, an injection nozzle 126, a nozzle touch device 127, and a temperature sensor. The heating cylinder 122 and the injection nozzle 126 respectively correspond to the "cylinder" and "nozzle" of the present disclosure. The temperature sensors are the temperature sensors T1 to T7 in FIG. 2 described later.

[0019] The base 121 is disposed on the floor surface on the positive X-axis side of the bed 111, and the operating device 124 is mounted on its upper surface. Servo motors 153 and 154 are arranged in the operating device 124.

[0020] The operating device 124 is provided with a heating cylinder 122 extending in the X-axis direction. The heating cylinder 122 includes a heating device (heating device 18 in FIG. 2 described later) for heating the interior and a screw 123. The screw 123 is driven by a servo motor 153 in the operating device 124 and is configured to be rotatable about the X-axis direction as the rotation axis. Further, the screw 123 is driven by a servo motor 154 and is configured to be movable in the X-axis direction.

[0021] The injection nozzle 126 is disposed at the tip of the heating cylinder 122 on the side of the mold clamping device 110 (that is, the end in the negative X-axis direction). The heating cylinder 122 heats and melts the bead-shaped resin material input from the hopper 125 and kneads it using the screw 123 to generate a molten material. Thus, the process of melting the resin material is referred to as the "plasticization" process. In this plasticization process, a process of measuring the molten material used for one shot is also included.

[0022] The nozzle touch device 127 is composed of, for example, a mechanism using a hydraulic cylinder or a mechanism using a ball screw, and connects the actuator 124 to the fixed platen 112 of the clamping device 110. When the nozzle touch device 127 is composed of a mechanism using a ball screw, the nozzle touch device 127 is driven by the actuator 124, which moves the actuator 124 and the heating cylinder 122 in the X-axis direction. The nozzle touch device 127 brings the injection nozzle 126 into contact with the sprue bush of the mold 118 in the clamping device 110, and injects the molten material from the injection nozzle 126, thereby injecting the molten material into the molds 117 and 118. The molten material then fills the cavities of the molds 117 and 118. The servo motor 154 applies pressure to the molten material by moving the screw 123 in the heating cylinder 122 in the negative direction of the X axis, injecting the molten material into the molds 117 and 118, and maintaining a constant pressure of the molten material after injection.

[0023] Furthermore, the configuration of the nozzle touch mechanism is not limited to the configuration in which the entire injection device is moved by a ball screw positioned between the fixed platen 112 and the actuator 124 as described above; other configurations are also possible. For example, the device frame and the fixing member at the rear of the heating cylinder may be connected using a ball screw, and the heating cylinder itself may be moved toward the mold. Alternatively, the slide base on which the injection device is mounted may be connected to the device frame using a ball screw, and the injection device may be moved together with the slide base to bring the injection nozzle into contact with the mold.

[0024] The process of injecting molten material into molds 117 and 118 is called the "injection" process. Furthermore, the process of holding the molten material filled into molds 117 and 118 at a constant pressure and cooling it after the injection process is called the "holding pressure" process.

[0025] Once the holding pressure process is complete, the mold opening and ejection processes are performed to remove the molded product.

[0026] The injection molding machine 100 can continuously form products by cyclically repeating the processes of mold clamping, injection, holding pressure, plasticization, mold opening, and ejection.

[0027] The control device 140 is housed inside the base 121. The control device 140 includes a CPU 141, a memory 142, and a servo amplifier 143 for driving servo motors 151 to 154. The control device 140 acquires detection values ​​from various sensors located on the injection molding machine 100 and comprehensively controls the injection molding machine 100.

[0028] The control panel 130 is a device for the user to operate the injection molding machine 100, and includes a display 132 having a display area for displaying various images, and an input device such as a keyboard. The control panel 130 is connected to the control device 140 and can acquire and display the status of the injection molding machine 100, and output user operation signals from the input device to the control device 140.

[0029] The display 132 in this embodiment is a touch panel capable of displaying images and receiving user input (instructions). The control device 140 acquires user input (instructions). The operation panel 130 may be attached to the bed 111 or base 121 of the injection molding machine 100, or it may be located in a position independent of the injection molding machine 100.

[0030] [Heating cylinder and injection nozzle] Figure 2 is a diagram illustrating the heating cylinder 122 and the injection nozzle 126. The heating cylinder 122 is divided into several zones along the extension direction (the X-axis in Figure 1). In the example in Figure 2, the heating cylinder 122 is divided into five zones: zone CZ1, zone CZ2, zone CZ3, zone CZ4, and zone CZ5. Similarly, the injection nozzle 126 is also divided into several zones along the extension direction. In the example in Figure 2, the injection nozzle 126 is divided into two zones: zone NZ1 and zone NZ2.

[0031] Zone CZ1 is the zone to which the injection nozzle 126 is connected, and corresponds to the “connection zone” in this disclosure. Zone CZ2 is the zone adjacent to Zone CZ1, and corresponds to the “adjacent zone” in this disclosure.

[0032] The heating device 18 can individually heat the heating cylinder 122 and the injection nozzle 126 under the control of the control device 140. The heating device 18 includes a plurality of heaters corresponding to each heating zone. In the example in Figure 2, the heating device 18 includes heaters 181, 182, 183, 184, 185, 186, and 187. Heaters 181 to 185 heat zones CZ1 to CZ5, respectively. Heaters 186 and 187 heat zones NZ1 and NZ2, respectively.

[0033] Furthermore, the injection device 120 is equipped with temperature sensors T1, T2, T3, T4, T5, T6, and T7. Temperature sensors T1 to T7 detect the temperatures of zones CZ1 to CZ5, zone NZ1, and zone NZ2, respectively. The detected temperatures from each temperature sensor are output to the control device 140.

[0034] The control device 140 stores the set temperature for each zone. The set temperatures for each zone may be the same, or at least two of the set temperatures for each zone may be different.

[0035] The control device 140 individually controls each heater using PID (Proportional Integral Derivative) control so that the temperature detected by each temperature sensor matches the set temperature for each zone.

[0036] In this embodiment, the control device 140 simultaneously starts heating heaters 181 to 187. Then, after the detected temperature of each zone reaches the set temperature corresponding to that zone, the injection molding machine 100 starts the injection molding process.

[0037] Generally, the volume of the injection nozzle is smaller than the volume of the heating cylinder, and furthermore, since the material to be injected is stored in the heating cylinder, the heat capacity of the heating cylinder is larger than the heat capacity of the injection nozzle. Therefore, when the same amount of heat is applied to both the injection nozzle and the heating cylinder, the heating rate of the injection nozzle will be faster than the heating rate of the heating cylinder.

[0038] Therefore, when heating the injection nozzle and heating cylinder, the injection nozzle reaches its set temperature earlier than the heating cylinder reaches its set temperature. In this case, after the injection nozzle reaches its set temperature, it is necessary to continue heating the injection nozzle to maintain its temperature until the heating cylinder reaches its set temperature. Consequently, a problem may arise where power is wasted in order to maintain the injection nozzle's temperature.

[0039] Therefore, the control device 140 in this embodiment controls the temperature of the injection nozzle 126 based on the temperature of the heating cylinder 122 detected by the temperature sensor T2 (described later) so as not to exceed the temperature of the heating cylinder 122. More specifically, when heating the injection nozzle 126, the control device 140 controls the heaters of the injection nozzle 126 (heaters 186 and 187) under certain conditions, using the detected temperature of a predetermined part of the heating cylinder 122, which heats up more slowly than the injection nozzle 126, as the target temperature. By this control, the control device 140 can slow down the heating rate of the injection nozzle 126 by heating the injection nozzle 126 in synchronization with a predetermined part of the heating cylinder 122.

[0040] Therefore, the injection molding machine 100 can delay the timing at which the injection nozzle 126 reaches the set temperature. As a result, in the injection molding machine 100 of this embodiment, unnecessary power consumption for maintaining the temperature of the injection nozzle can be suppressed. Hereinafter, the zone of a predetermined portion of the heating cylinder 122 will also be referred to as the "synchronous zone".

[0041] In this embodiment, the synchronization zone is defined as the portion of the heating cylinder 122 that corresponds to a zone with a larger heat capacity than the injection nozzle 126 (i.e., a zone with a slower heating rate). Therefore, the injection molding machine 100 can delay the timing at which the detected temperature of the injection nozzle 126 reaches the set temperature, and as a result, power consumption can be suppressed.

[0042] Furthermore, in this embodiment, the synchronization zone is set to zone CZ2 of the heating cylinder 122, which has the largest heat capacity (i.e., the zone with the slowest heating rate). Therefore, the timing at which the detected temperature of zone CZ2 reaches the set temperature is the latest. Thus, the injection molding machine 100 can delay the timing at which the detected temperature of the injection nozzle 126 reaches the set temperature to the latest timing. As a result, the injection molding machine 100 can reduce wasted power more effectively compared to when the synchronization zone is set to any other zone of the heating cylinder 122.

[0043] As described above, the temperature of the synchronization zone is detected by the temperature sensor T2. The injection molding machine 100 PID controls the heater of the injection nozzle 126 based on the detected temperature of the synchronization zone. The temperature sensors T6 and T7 that detect the temperature of the injection nozzle 126 correspond to the "nozzle temperature sensor" in this disclosure. In addition, the temperature sensor T2 that detects the temperature of the synchronization zone (zone CZ2) corresponds to the "cylinder temperature sensor" in this disclosure.

[0044] [Functional block diagram of the control unit] Figure 3 is a functional block diagram of the control device 140. The control device 140 includes a setting unit 191, a subtraction unit 192, a PID control unit 193, and a memory 142. Figure 3 is a diagram illustrating the control of the heater 186 for heating zone NZ1 of the injection nozzle 126. In Figure 3, the case of heating zone NZ1 of the injection nozzle 126 is used as an example.

[0045] The control device 140 heats zone NZ1 using the detected temperature of the synchronization zone as the target temperature until the temperature detected by the temperature sensor T6 approaches the set temperature of zone NZ1. Then, when the detected temperature of zone NZ1 approaches the set temperature of zone NZ1, the control device 140 switches the target temperature to the set temperature of zone NZ1 and heats zone NZ1.

[0046] In the following explanation, "Target Temperature" refers to the target temperature in the PID control for each zone. "Set Temperature" is the final temperature that each zone will reach. "Reference Temperature" is the temperature that indicates the point at which the target temperature is switched (switching point), as described above. In other words, the reference temperature is the temperature used to determine whether the detected temperature of zone NZ1 is approaching the set temperature of zone NZ1.

[0047] Memory 142 stores the set temperature and reference temperature for each zone. In this embodiment, the reference temperature is calculated by subtracting the proportional band from the set temperature. In this embodiment, the reference temperature includes the nozzle reference temperature for zone NZ1 and the cylinder reference temperature for the synchronization zone.

[0048] The nozzle reference temperature is calculated by subtracting the proportional band of Zone NZ1 from the set temperature of Zone NZ1. The proportional band of Zone NZ1 is the reciprocal of the proportional gain used in the P control of Zone NZ1's PID control. The nozzle reference temperature is the temperature at which, during the heating of Zone NZ1, the detected temperature of Zone NZ1 approaches the set temperature of Zone NZ1.

[0049] The cylinder reference temperature is calculated by subtracting the proportional band of the synchronous zone from the set temperature of the synchronous zone. The proportional band of the synchronous zone is the reciprocal of the proportional gain used in the P control of the synchronous zone's PID control. The cylinder reference temperature is the temperature at which the detected temperature of the synchronous zone approaches the set temperature of the synchronous zone during the heating process.

[0050] The set temperature of zone NZ1 corresponds to the “nozzle set temperature” in this disclosure. The set temperature of the synchronization zone corresponds to the “cylinder set temperature” in this disclosure. The proportional band of zone NZ1 corresponds to the “predetermined nozzle temperature” in this disclosure. The proportional band of the synchronization zone corresponds to the “predetermined cylinder temperature” in this disclosure. The proportional gain of zone NZ1 corresponds to the “nozzle proportional gain” in this disclosure. The proportional gain of the synchronization zone corresponds to the “cylinder proportional gain” in this disclosure.

[0051] Furthermore, the temperature detected by the synchronization zone from temperature sensor T2 and the temperature detected by zone NZ1 from temperature sensor T6 are input to the setting unit 191. The setting unit 191 also acquires the set temperature of NZ1, the nozzle reference temperature, and the cylinder reference temperature from memory 142.

[0052] The setting unit 191 sets the detected temperature of the synchronization zone or the set temperature of zone NZ1 as the target temperature using the method described in steps S2 to S8 of Figure 4 below.

[0053] The subtraction unit 192 calculates the deviation e by subtracting the detected temperature of zone NZ1 from the set target temperature. The deviation e is input to the PID control unit 193. The PID control unit 193 calculates the manipulated amount for the heater 186 by performing a PID control calculation on the deviation e and controls the heater 186.

[0054] [Flowchart of the control device] Figure 4 is a flowchart illustrating the main processes performed by the control device 140. The control device 140 executes the processes shown in this flowchart at predetermined intervals (for example, 1 ms).

[0055] First, in step S2, the control device 140 determines whether the detected temperature of the injection nozzle 126 is lower than the nozzle reference temperature. If the detected temperature of the injection nozzle 126 is lower than the nozzle reference temperature (YES in step S2), the process proceeds to step S4.

[0056] In step S4, the control device 140 determines whether the detected temperature of the synchronization zone of the heating cylinder 122 is lower than the cylinder reference temperature. If the detected temperature of the synchronization zone is lower than the cylinder reference temperature (YES in step S4), that is, if it is the initial state after heating of the injection nozzle 126 and the heating cylinder 122 has started, the process proceeds to step S6.

[0057] In step S6, the control device 140 sets the target temperature of the injection nozzle 126 to the detected temperature of the synchronization zone of the heating cylinder 122. Therefore, the process in step S6 allows the injection molding machine 100 to synchronize the heating rate of the injection nozzle 126 with the heating rate of the synchronization zone of the heating cylinder 122 in the initial state described above. This allows the injection molding machine 100 to slow down the heating rate of the injection nozzle 126 in the initial state described above.

[0058] On the other hand, if the detected temperature of the injection nozzle 126 is higher than the nozzle reference temperature (NO in step S2), that is, if the detected temperature of the injection nozzle 126 approaches the set temperature of the injection nozzle 126, the control device 140 proceeds to step S8. Also, if the detected temperature of the synchronization zone of the heating cylinder 122 is higher than the cylinder reference temperature (NO in step S4), that is, if the synchronization zone of the heating cylinder 122 approaches the set temperature of that zone, the control device 140 proceeds to step S8.

[0059] In step S8, the control device 140 returns the target temperature of the injection nozzle 126 to the set temperature of the injection nozzle 126. As a result, when the detected temperature of the injection nozzle 126 approaches the set temperature of the injection nozzle 126, the control device 140 sets the temperature of the injection nozzle 126 to the set temperature of the injection nozzle 126, thereby ultimately heating it to the target temperature.

[0060] After the completion of the processing in step S6 or step S8, in step S10, the control device 140 performs PID control using the set target temperature of the injection nozzle 126. Note that the PID control is the processing of the subtraction unit 192 and the PID control unit 193 in Figure 3.

[0061] As described above, the control device 140 controls the detected temperature of the injection nozzle 126 based on the detected temperature of the heating cylinder 122, so as not to exceed the temperature of the heating cylinder 122. More specifically, in the initial state when the nozzle temperature is sufficiently lower than the set temperature, the control device 140 switches the target temperature of the injection nozzle 126 to the detected temperature of the synchronization zone and performs heating control, thereby slowing down the rate at which the injection nozzle 126 heats up (step S6). Then, as the heating progresses over time and the detected temperature of the injection nozzle 126 approaches the set temperature of the injection nozzle 126, the control device 140 returns the target temperature of the injection nozzle 126 to the set temperature of the injection nozzle 126 and performs heating control (step S8). Therefore, the control device 140 can heat the injection nozzle 126 to the final set temperature while delaying the timing at which the injection nozzle 126 reaches the set temperature until the timing at which the synchronization zone reaches the set temperature. Thus, the injection molding machine 100 of this embodiment can suppress the power consumed when heating the injection nozzle 126.

[0062] Furthermore, the target temperature of the injection nozzle is set by comparing the detected temperature of the injection nozzle 126 with the nozzle reference temperature, as shown in step S2 of Figure 4, and by comparing the detected temperature of the synchronization zone with the cylinder reference temperature, as shown in step S4. Therefore, the injection molding machine 100 of this embodiment can suppress power consumption in temperature control of the injection nozzle 126 with relatively simple processing without requiring complex calculations.

[0063] Furthermore, as shown in Figure 3, the reference temperature is set using a "proportional band." Therefore, the injection molding machine 100 can be set to a switching point that takes the control gain into consideration as the target temperature switching point, thus enabling a switching point that is suitable for control and achieving smooth control. Since the unit of the proportional band is temperature, the user can easily understand the switching point.

[0064] [Simulation Results] Figure 5 shows the simulation results to explain the effects of the injection molding machine 100 of this embodiment. Figure 5(A) shows the simulation results of an injection molding machine of a comparative example. The injection molding machine of the comparative example controls each heater with the set temperature corresponding to each zone as the target temperature. Figure 5(B) shows the simulation results of the injection molding machine 100 of this embodiment. The vertical axis in Figures 5(A) and 5(B) shows the temperature detected by temperature sensors T1 to T7, and the horizontal axis in Figures 5(A) and 5(B) shows time.

[0065] In Figures 5(A) and 5(B), the set temperatures for the seven zones (zones CZ1-CZ5, NZ1, and NZ2) are shown by dashed lines. In this simulation example, the set temperatures for all seven zones are set to the same value.

[0066] As mentioned above, the heating rate of the injection nozzle is faster than that of the heating cylinder. Therefore, in the comparative example, as shown in the graph of temperature sensors T6 and T7 in Figure 5(A), the timing at which the detected temperature of the injection nozzle reaches the set temperature is earlier than the timing at which the detected temperature of the heating cylinder reaches the set temperature. In this case, after the injection nozzle temperature reaches the set temperature, heating of the injection nozzle must be continued to maintain the temperature until the heating cylinder temperature reaches the set temperature, resulting in wasted power consumption.

[0067] In contrast, in FIG. 5(B) to which the control of the present embodiment is applied, the injection molding machine 100 controls the detected temperature of the injection nozzle 126 (the detected temperatures by the temperature sensors T1 to T5) so as not to exceed the temperature of the heating cylinder 122 (the detected temperatures by the temperature sensors T6 and T7). More specifically, the injection molding machine 100 can synchronize the temperature increase rate of the injection nozzle 126 with the temperature increase rate of the synchronization zone by executing the process of FIG. 4 to switch and control the control target temperature. Therefore, the timing at which the detected temperature of the injection nozzle 126 reaches the set temperature can be delayed, and as a result, the power consumed in the temperature control of the injection nozzle 126 can be suppressed.

[0068] <Other Embodiments> (1) Although an example in which the "proportional band" is used as the "predetermined temperature" for determining the switching point has been shown, the predetermined temperature does not necessarily have to coincide with the proportional band. The predetermined temperature may be set, for example, to a value within a range of plus or minus 20% with respect to the proportional band.

[0069] That is, the upper limit value of the nozzle predetermined range of the nozzle predetermined temperature is a value obtained by multiplying the nozzle proportional band by a real number A (A > 1), and the lower limit value of this nozzle predetermined range is a value obtained by multiplying the nozzle proportional band by a real number B (0 < B < 1). For example, A = 1.2 and B = 0.8.

[0070] Also, the upper limit value of the cylinder predetermined range of the cylinder predetermined temperature is a value obtained by multiplying the cylinder proportional band by a real number C (C > 1), and the lower limit value of this cylinder predetermined range is a value obtained by multiplying the cylinder proportional band by a real number D (0 < D <1). For example, C = 1.2 and D = 0.8.

[0071] (2) In the above embodiment, the synchronization zone has been described as being the zone CZ2 having the largest heat capacity among the heating cylinders 122. However, the synchronization zone may be a zone different from the zone CZ2 of the heating cylinder 122.

[0072] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of symbols]

[0073] 18 Heating device, 100 Injection molding machine, 110 Clamping device, 111 Bed, 112 Fixed platen, 113 Clamping housing, 114 Movable platen, 115 Tie bar, 116 Clamping mechanism, 117,118 Mold, 119 Ball screw, 120 Injection device, 121 Base, 122 Heating cylinder, 123 Screw, 124 Actuator, 125 Hopper, 126 Injection nozzle, 127 Nozzle touch device, 130 Control panel, 132 Display, 140 Control device, 142 Memory, 143 Servo amplifier, 151,152,153,154 Servo motor, 181~187 Heater, T1~T7 Temperature sensor.

Claims

1. Injection molding machines including the following: An injection molding device that melts and injects injection material; A clamping device for clamping the mold from which the injection material has been injected; and Control device for controlling the injection device, Here, the injection device is Cylinder and A screw is placed inside the cylinder and heats the injection material to generate a molten material, A nozzle provided at the tip of the cylinder for injecting the heated molten material into the mold, A nozzle temperature sensor for detecting the temperature of the nozzle, A cylinder temperature sensor for detecting the temperature of the cylinder, The control device controls the heating device which is capable of independently heating the nozzle and the cylinder, respectively. The temperature of the nozzle is controlled by the control device so as not to exceed the temperature of the cylinder, based on the temperature detected by the cylinder temperature sensor.

2. The cylinder temperature sensor detects the temperature of a predetermined part of the cylinder, The heating rate of the nozzle is faster than the heating rate of the predetermined portion. The control device controls the heating device so that the temperature of the nozzle reaches the nozzle set temperature. The control device, when the nozzle reference temperature is set to the nozzle set temperature minus the predetermined nozzle temperature, ensures that the temperature of the nozzle does not exceed the temperature of the cylinder. If the temperature of the nozzle is lower than the nozzle reference temperature, the nozzle is heated using the temperature of the predetermined portion measured by the cylinder temperature sensor as the target temperature. The injection molding machine according to claim 1, wherein if the temperature of the nozzle is higher than the nozzle reference temperature, the nozzle is heated to the nozzle set temperature as the target temperature.

3. The cylinder is divided into a plurality of zones along the extension direction of the cylinder, The heating device is capable of individually heating the multiple zones. The injection molding machine according to claim 2, wherein the predetermined portion is a portion of the plurality of zones that corresponds to a zone with a larger heat capacity than the nozzle.

4. The injection molding machine according to claim 3, wherein the predetermined portion is the zone with the largest heat capacity among the plurality of zones.

5. The aforementioned multiple zones are, The connection zone to which the nozzle is connected, The aforementioned connection zone includes adjacent zones, The injection molding machine according to claim 4, wherein the predetermined portion is the adjacent zone.

6. The control device uses a nozzle-proportional gain to control the heating device that heats the nozzle, The injection molding machine according to any one of claims 2 to 5, wherein the predetermined nozzle temperature is set within a predetermined range that includes the reciprocal of the nozzle proportional gain.

7. The injection molding machine according to claim 6, wherein the predetermined nozzle temperature is the reciprocal of the nozzle proportional gain.

8. The control device controls the heating device so that the temperature of the predetermined portion reaches the cylinder set temperature. The control device, when it subtracts the predetermined cylinder temperature from the cylinder set temperature, sets the cylinder reference temperature as follows: The injection molding machine according to any one of claims 2 to 5, wherein when the temperature of the nozzle is lower than the nozzle reference temperature, and the temperature of the predetermined portion is lower than the cylinder reference temperature, the nozzle is heated with the temperature of the predetermined portion as the target temperature.

9. The injection molding machine according to claim 8, wherein the control device heats the nozzle with the nozzle set temperature as the target temperature when the temperature of the nozzle is lower than the nozzle reference temperature and the temperature of the predetermined part is higher than the cylinder reference temperature.

10. The control device uses a cylinder proportional gain to control the heating device that heats the predetermined portion, The injection molding machine according to claim 8, wherein the predetermined temperature of the cylinder is set within a predetermined range that includes the reciprocal of the proportional gain of the cylinder.

11. The injection molding machine according to claim 10, wherein the predetermined cylinder temperature is the reciprocal of the cylinder proportional gain.

12. Injection devices including the following: Cylinder; A screw positioned inside the cylinder, which heats the injection material to produce a molten material; A nozzle provided at the tip of the cylinder for injecting the heated molten material into the mold; A nozzle temperature sensor for detecting the temperature of the nozzle; A cylinder temperature sensor for detecting the temperature of the cylinder; and A heating device capable of independently heating the nozzle and the cylinder, Here, the temperature of the nozzle can be controlled so as not to exceed the temperature of the cylinder, based on the temperature detected by the cylinder temperature sensor.

13. A method for controlling an injection molding machine, including the following: The injection molding machine is, An injection molding device that melts and injects the injection material, The system includes a clamping device for clamping the mold from which the injection material has been injected, The injection device is, Cylinder and A screw is placed inside the cylinder and heats the injection material to generate a molten material, The cylinder has a nozzle provided at its tip for injecting the heated molten material into the mold, (a) A step of controlling the temperature of the nozzle based on the temperature of the cylinder so as not to exceed the temperature of the cylinder.

14. The heating rate of the nozzle is faster than the heating rate of a predetermined portion of the cylinder. If the nozzle reference temperature is defined as the temperature obtained by subtracting the predetermined nozzle temperature from the nozzle set temperature of the aforementioned nozzle, To prevent the temperature of the nozzle from exceeding the temperature of the cylinder, step (a) includes the following method for controlling an injection molding machine according to claim 13: (b) If the temperature of the nozzle is lower than the nozzle reference temperature, the step of heating the nozzle with the temperature of the predetermined portion as the target temperature; (c) If the nozzle temperature is higher than the nozzle reference temperature, the nozzle is heated to the nozzle set temperature as the target temperature.

15. The cylinder is divided into a plurality of zones along the extension direction of the cylinder, The aforementioned multiple zones can be heated individually. The method for controlling an injection molding machine according to claim 14, wherein the predetermined portion is a portion of the plurality of zones that corresponds to a zone with a larger heat capacity than the nozzle.

16. The method for controlling an injection molding machine according to claim 15, wherein the predetermined portion is the zone with the largest heat capacity among the plurality of zones.

17. The aforementioned multiple zones are, The connection zone to which the nozzle is connected, The aforementioned connection zone includes adjacent zones, The method for controlling an injection molding machine according to claim 16, wherein the predetermined portion is the adjacent zone.

18. In the control method for the injection molding machine, a nozzle proportional gain is used to heat the nozzle. The method for controlling an injection molding machine according to any one of claims 14 to 17, wherein the predetermined nozzle temperature is set within a predetermined range that includes the reciprocal of the nozzle proportional gain.

19. The method for controlling an injection molding machine according to claim 18, wherein the predetermined nozzle temperature is the reciprocal of the nozzle proportional gain.

20. If the temperature obtained by subtracting the predetermined cylinder temperature from the cylinder set temperature of the predetermined portion is taken as the cylinder reference temperature, Step (a) is a control method for an injection molding machine according to any one of claims 14 to 17, which includes the following method: (e) When the temperature of the nozzle is lower than the nozzle reference temperature, and the temperature of the predetermined portion is lower than the cylinder reference temperature, the nozzle is heated with the temperature of the predetermined portion as the target temperature.

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