Mold opening and closing control method, system, and injection molding machine

Abstract

This invention proposes a mold opening and closing control method, system, and injection molding machine. The method switches the operating mode of a hydraulic auxiliary device according to different motion stages and controls the operation of the hydraulic auxiliary device according to the determined operating mode. The operating modes include a replenishing oil mode and an assist mode. During non-critical stages of mold opening and closing, such as the initial startup or near the end point, the hydraulic auxiliary device automatically enters the replenishing oil mode. The hydraulic auxiliary device maintains or replenishes the oil pressure in the hydraulic system, ensuring that the hydraulic system can respond quickly when needed, while reducing unnecessary hydraulic energy consumption. During critical stages of mold opening and closing, such as rapid mold opening and closing or under heavy loads, the hydraulic auxiliary device quickly switches to the assist mode, providing strong hydraulic pressure to the mold closing device, ensuring that the injection molding machine can smoothly complete heavy-load operations while maintaining the smoothness and accuracy of movement.

Description

Technical Field

[0001] This invention relates to the field of injection molding machine technology, and in particular to a mold opening and closing control method, system and injection molding machine. Background Technology

[0002] Injection molding machines are core equipment for manufacturing plastic products of various shapes, mainly through the processing and molding of thermoplastic or thermosetting materials. However, in practical applications, all-motor injection molding machines suffer from insufficient output tonnage (i.e., the clamping force or injection pressure that the injection molding machine can generate) due to factors such as motor performance, structural design, or control system. Therefore, how to overcome the low output tonnage limitation of all-motor injection molding machines while retaining their energy-saving and high-efficiency advantages is a problem that needs to be solved. Summary of the Invention

[0003] The main objective of this invention is to propose a mold opening and closing control method, system, and injection molding machine, which aims to retain the energy-saving and high-efficiency advantages of all-motor injection molding machines while solving the problem of low output tonnage limitation of all-motor injection molding machines.

[0004] To address the aforementioned shortcomings, this invention proposes a mold opening and closing control method, the control method comprising: The motion phase of the injection molding machine is obtained, and the servo motor is controlled to drive the mold clamping device to move. Based on the motion phase, the working mode of the hydraulic auxiliary device is determined, and the operation of the hydraulic auxiliary device is controlled according to the determined working mode; wherein, the working mode includes a replenishing oil mode and an assist mode, and in the replenishing oil mode, the hydraulic auxiliary device stores oil; In the power-assisted mode, the hydraulic auxiliary device provides assistance to the mold-closing device.

[0005] Optionally, the motion phase includes a mold closing phase and a mold opening phase; During the mold closing stage, the hydraulic auxiliary device operates in either oil replenishment mode or power assist mode. During the mold opening stage, the hydraulic auxiliary device operates in oil replenishment mode.

[0006] Optionally, the mold closing stage includes three sub-stages: pre-mold closing, mold protection, and high-pressure mold locking; During the pre-mold closing stage in the mold closing phase, the hydraulic auxiliary device operates in oil replenishment mode; During the mold protection stage in the mold closing stage, the hydraulic auxiliary device operates in oil replenishment mode; During the high-pressure locking stage of the mold closing phase, the hydraulic auxiliary device operates in assist mode.

[0007] Optionally, the working mode also includes a mold-breaking mode; In the mold-breaking mode, the hydraulic auxiliary device provides a mold-breaking force to the mold-closing device.

[0008] Optionally, the mold-opening stage includes two sub-stages: mold breaking and final mold opening; During the mold-breaking sub-stage of the mold-opening stage, the hydraulic auxiliary device operates in mold-breaking mode; during the final mold-opening sub-stage of the mold-opening stage, the hydraulic auxiliary device operates in oil replenishment mode.

[0009] Optionally, the mold opening and closing control method further includes the following steps: The torque of the servo motor is obtained during the mold closing or mold opening stage. When the torque of the servo motor is greater than the preset torque, the hydraulic auxiliary device switches from the oil replenishment mode to the power assist mode. When the torque of the servo motor does not meet the requirement of being greater than the preset torque, the hydraulic auxiliary device operates in the oil replenishment mode.

[0010] Optionally, after the hydraulic auxiliary device switches from the replenishment mode to the power assist mode, the method further includes: After the hydraulic auxiliary device operates in the power assist mode for a preset time, the torque of the servo motor is reacquired. When the torque of the servo motor is greater than the preset torque, the system will determine to return to the oil replenishment mode in a loop until the current stage ends.

[0011] Optionally, the mold opening and closing control method further includes: During the high-pressure mold-locking sub-stage of the mold-closing phase, the hydraulic auxiliary device operates in assist mode, and the operating mode of the hydraulic auxiliary device is independent of the torque of the servo motor.

[0012] The present invention also proposes an opening and closing mold control system, comprising: Memory; The processor stores the mold opening and closing control program in the memory and executes it. When the mold opening and closing control program is executed by the processor, it implements the mold opening and closing control method as described above.

[0013] The present invention also proposes an injection molding machine, including a servo motor, a hydraulic auxiliary device, a mold closing device, and a mold opening and closing control system as described above.

[0014] This invention proposes a mold opening and closing control method. This method switches the operating mode of the hydraulic auxiliary device according to different motion stages, and controls the operation of the hydraulic auxiliary device according to the determined operating mode. During non-critical stages of mold opening and closing in the injection molding machine, such as the initial startup or near the end point, the hydraulic auxiliary device automatically enters the oil replenishment mode. The hydraulic auxiliary device maintains or replenishes the oil pressure in the hydraulic system, ensuring that the hydraulic system can respond quickly when needed, while reducing unnecessary hydraulic energy consumption. During critical stages of mold opening and closing in the injection molding machine, such as rapid mold opening and closing or under heavy loads, the hydraulic auxiliary device quickly switches to the assist mode, providing strong hydraulic pressure to the mold closing device, ensuring that the injection molding machine can smoothly complete heavy load operations while maintaining the smoothness and accuracy of the movement. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the steps of a mold opening and closing control method according to the present invention; Figure 2 This is a flowchart of an embodiment of a mold opening and closing control method according to the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0020] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0022] This invention proposes a mold opening and closing control method, the control method comprising: S100: Obtains the motion stage of the injection molding machine and controls the servo motor to drive the mold clamping device to move; S200: Determine the working mode of the hydraulic auxiliary device according to the motion stage, and control the operation of the hydraulic auxiliary device according to the determined working mode; wherein, the working mode includes oil replenishment mode and power assist mode, and in oil replenishment mode, the hydraulic auxiliary device stores oil; In the power-assisted mode, the hydraulic auxiliary device provides assistance to the mold closing device.

[0023] More specifically, injection molding machines are core equipment for manufacturing plastic products of various shapes, primarily through the processing and molding of thermoplastic or thermosetting materials. With hydraulic assistance, injection molding machines can achieve higher output tonnage, thus meeting the production needs of medium to large-sized plastic products. However, in practical applications, fully servo motor injection molding machines suffer from insufficient output tonnage (i.e., the clamping force or injection pressure that the machine can generate) due to factors such as servo motor performance, structural design, or control system limitations. Therefore, how to solve the problem of low output tonnage limitation in fully servo motor injection molding machines while retaining their energy-saving and high-efficiency advantages is a problem that needs to be addressed.

[0024] Therefore, this application proposes a mold opening and closing control method, which enables the hydraulic auxiliary device to enter different working modes according to the motion stage of the injection molding machine, so as to solve the problem of low output tonnage limitation of the all-servo motor injection molding machine and realize a high-efficiency and energy-saving injection molding process.

[0025] The method includes the following steps: In step S100, the motion stage of the injection molding machine is acquired, and the servo motor is controlled to drive the mold closing device. The motion stages of the injection molding machine typically include multiple stages such as mold closing, mold holding, mold locking, and mold opening, each of which requires different mechanical actions and parameter settings. For example, in the mold closing stage of the injection molding machine, the servo motor drives the mold closing device to perform opening and closing actions through a transmission device. The control system precisely controls the operation of the servo motor according to the preset program and parameters to achieve fast, smooth, and accurate action of the mold closing device.

[0026] More specifically, the motion phases of an injection molding machine typically include mold closing, mold holding, mold locking, and mold opening. During the mold closing phase, the mold closing device of the injection molding machine begins to close, making the mold a closed cavity, preparing for the subsequent injection of plastic. The mold closing process requires precise control to ensure that the mold is completely closed and the mold gap is uniform, avoiding plastic leakage and product quality problems.

[0027] During the molding stage, molten plastic is injected into the mold cavity under high pressure. The injection molding machine continues to apply a certain pressure to the plastic inside the mold to compensate for the shrinkage during the cooling process. This stage helps to reduce shrinkage cavities and depressions inside the product and improve the dimensional stability and surface quality of the product.

[0028] During the mold-locking stage, the mold of the mold-closing device is completely closed and locked together to ensure that the mold will not open during injection and mold protection. Therefore, a large mold-locking force is required at this stage to ensure that the mold remains tightly closed during injection and mold protection, preventing molten plastic from leaking under high pressure or the mold from being forced open, thereby ensuring the quality and dimensional stability of the product.

[0029] During the mold opening stage, the injection molding machine begins to open the mold to remove the product. The mold opening stage generally includes two motion phases: first, mold breaking, where the mold begins to separate initially under the drive of a servo motor; and second, mold opening, where the servo motor continuously provides power to push the mold further apart. Because a certain separation force is generated between the mold cavity and core during mold breaking—due to the shrinkage force formed after the plastic cools and solidifies and the elastic deformation of the mold itself—the power required for mold breaking is greater than the power required for mold opening.

[0030] The movement of an injection molding machine is a cyclical process: mold closing, mold holding, mold locking, mold opening, and then back to mold closing. The trigger condition for the injection molding machine to enter a movement phase is a pre-set position signal, that is, the movement phase of the injection molding machine is set according to the position state of the mold closing device during its operation. A position sensor is installed on the mold closing device. When the mold closing device is in the preset position, the system receives the position signal and triggers the injection molding machine to enter the corresponding movement phase.

[0031] In step S200, the working mode of the hydraulic auxiliary device is determined according to the motion stage, and the hydraulic auxiliary device is controlled to work according to the determined working mode; wherein, the working mode includes oil replenishment mode and power assist mode. In oil replenishment mode, the hydraulic auxiliary device stores oil; in power assist mode, the hydraulic auxiliary device provides power assist to the mold closing device.

[0032] To drive the hydraulic auxiliary device, this application introduces a programmable logic controller (PLC) connected to two servo drives. The PLC receives the servo motor speed and actual motor torque limits, and issues commands to servo drive 1 to control the servo motor and servo drive 2 to control the operation of the hydraulic auxiliary device, simultaneously driving the injection molding equipment to complete the system's motion phases.

[0033] By using the power source of the hydraulic auxiliary device as the auxiliary power of the servo motor, different assistance methods are provided according to the torque changes of the servo motor throughout the entire mold opening and closing process. This solves the problem of low output tonnage limitation of all-motor injection molding machines, and is suitable for medium and large-sized injection molding machines, while retaining the energy-saving and high-efficiency advantages of all-motor machines.

[0034] The hydraulic auxiliary device includes a hydraulic auxiliary cylinder, a cylinder control valve, and a buffer directional valve. The hydraulic auxiliary cylinder has a rodless chamber and a rod chamber that are interconnected. The drive end of the hydraulic auxiliary cylinder is used to connect to the mold closing device. The cylinder control valve is connected in series between the oil inlet and the hydraulic auxiliary cylinder. The buffer directional valve is connected in series between the cylinder control valve and the oil outlet.

[0035] In a hydraulic auxiliary device, hydraulic oil enters the hydraulic auxiliary cylinder from the oil tank through the inlet and then flows back to the oil tank. Since a piston rod exists in the rod chamber, if the inlet is connected to the rodless chamber of the hydraulic auxiliary cylinder, the hydraulic oil in the rodless chamber will push the piston and piston rod forward, thus generating a driving force. Similarly, if the inlet is connected to the rod chamber of the hydraulic auxiliary cylinder, the hydraulic oil in the rod chamber will push the piston and piston rod backward, thus generating a driving force in the opposite direction.

[0036] The hydraulic cylinder control valve controls the connection between the oil inlet and the rod-side or rodless chamber. The buffer directional valve diverts the hydraulic oil output from the hydraulic cylinder control valve, reducing the pressure of the hydraulic oil in the circuit. This lowers the hydraulic pressure in the hydraulic auxiliary cylinder, reducing the force required to drive the mold-closing device and thus reducing energy consumption.

[0037] The hydraulic auxiliary device has two operating modes: oil replenishment mode and power assist mode.

[0038] In the replenishment mode, the cylinder control valve is turned on, connecting the oil inlet and the rod chamber of the hydraulic auxiliary cylinder, so that the rod chamber outputs the hydraulic oil from the oil inlet to the rodless chamber, or the oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected, so that the rodless chamber outputs the hydraulic oil from the oil inlet to the rod chamber. The buffer directional valve is turned on, connecting the cylinder control valve and the oil outlet, so that the hydraulic oil output by the cylinder control valve is buffered and then output to the oil tank, so that the hydraulic auxiliary cylinder stores oil. In the power assist mode, the cylinder control valve is turned on and the buffer directional valve is turned off, connecting the control oil inlet and the rodless chamber of the hydraulic auxiliary cylinder, so that the rodless chamber outputs the hydraulic oil from the oil inlet to the rod chamber to provide power assist to the mold closing device.

[0039] During the mold closing and mold holding stages, the servo motor needs to provide a driving force to control the mold closing device to close the mold and maintain the pressure within the mold cavity. In these two stages, the injection molding machine's servo motor can provide sufficient driving force to drive the mold closing device to perform the mold closing and mold holding actions; therefore, the hydraulic auxiliary device does not need to provide assistance to the mold closing device. At this time, the hydraulic auxiliary device enters the oil replenishment mode, and the hydraulic pump or oil reservoir within the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder, ensuring stable system pressure and reserving hydraulic oil for the mold clamping stage.

[0040] During the mold-closing stage, a large clamping force is required to ensure that the mold of the mold-closing device is completely closed and locked together. At this time, it is necessary to control the hydraulic auxiliary cylinder to provide necessary assistance to the mold-closing device. The hydraulic auxiliary device is controlled to enter the assistance mode. During this process, the hydraulic auxiliary cylinder quickly pressurizes and provides power, bearing part of the load, thereby reducing the burden on the servo motor.

[0041] Because the power required for mold breaking is greater than that required for mold opening, the hydraulic auxiliary device operates in different modes when assisting the servo motor during the mold opening stage. After completing mold breaking, the servo motor provides a driving force to control the mold closing device to open the mold. The servo motor can provide sufficient driving force to drive the mold closing device to perform the mold opening action, so the hydraulic auxiliary device does not need to provide assistance to the mold closing device. At this time, the hydraulic auxiliary device enters the oil replenishment mode, and the hydraulic pump or oil reservoir in the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder to ensure stable system pressure and reserve hydraulic oil for the next stage.

[0042] This invention proposes a mold opening and closing control method. This method switches the operating mode of the hydraulic auxiliary device according to different motion stages, and controls the operation of the hydraulic auxiliary device according to the determined operating mode. During non-critical stages of mold opening and closing in the injection molding machine, such as the initial startup or near the end point, the hydraulic auxiliary device automatically enters the oil replenishment mode. The hydraulic auxiliary device maintains or replenishes the oil pressure in the hydraulic system, ensuring that the hydraulic system can respond quickly when needed, while reducing unnecessary hydraulic energy consumption. During critical stages of mold opening and closing in the injection molding machine, such as rapid mold opening and closing or under heavy loads, the hydraulic auxiliary device quickly switches to the assist mode, providing strong hydraulic pressure to the mold closing device, ensuring that the injection molding machine can smoothly complete heavy load operations while maintaining the smoothness and accuracy of the movement.

[0043] In one embodiment, the motion phase includes a mold closing phase and a mold opening phase; During the mold closing stage, the hydraulic auxiliary device operates in either oil replenishment mode or power assist mode. During the mold closing stage, the injection molding machine's mold closing device begins to close, forming a closed cavity. Molten plastic is injected into the mold cavity under high pressure. The injection molding machine continues to apply pressure to the plastic inside the mold to compensate for shrinkage during the cooling process. Afterward, the mold closing device is completely closed and locked together to ensure that the mold will not open during injection and mold protection, preventing molten plastic leakage under high pressure or the mold from being forced open, thus guaranteeing product quality and dimensional stability.

[0044] During the mold clamping process, such as when the clamping device begins to close or when molten plastic is injected into the mold cavity under high pressure, the servo motor needs to provide a driving force to control the clamping device to close the mold and maintain the pressure within the mold cavity. In these two stages, the injection molding machine's servo motor can provide sufficient driving force to drive the clamping device to perform the clamping and mold holding actions; therefore, the hydraulic auxiliary device does not need to provide assistance to the clamping device. At this time, the hydraulic auxiliary device enters the oil replenishment mode, and the hydraulic pump or oil reservoir within the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder, ensuring stable system pressure and reserving hydraulic oil for the mold clamping stage.

[0045] To ensure that the mold of the mold clamping device is completely closed and locked together, a large clamping force is required. At this time, it is necessary to control the hydraulic auxiliary cylinder to provide the necessary assistance to the mold clamping device. Control the hydraulic auxiliary device to enter the assistance mode. During this process, the hydraulic auxiliary cylinder quickly pressurizes and provides power, and undertakes part of the load, thereby reducing the burden on the servo motor.

[0046] During the mold opening stage, the hydraulic auxiliary device operates in oil replenishment mode. The mold opening stage provides a driving force to control the mold closing device to open the mold. The servo motor can provide sufficient driving force to drive the mold closing device to perform the mold opening action, therefore the hydraulic auxiliary device does not need to provide assistance to the mold closing device. At this time, the hydraulic auxiliary device enters the oil replenishment mode, and the hydraulic pump or oil reservoir within the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder, ensuring stable system pressure and reserving hydraulic oil for the next stage.

[0047] In one embodiment, such as Figure 2 As shown, the mold closing stage includes three sub-stages: pre-mold closing, mold protection, and high-pressure mold locking. During the pre-mold closing stage in the mold closing phase, the hydraulic auxiliary device operates in oil replenishment mode; During the mold protection stage in the mold closing stage, the hydraulic auxiliary device operates in oil replenishment mode; During the high-pressure locking stage of the mold closing phase, the hydraulic auxiliary device operates in assist mode.

[0048] In this embodiment, the motion stage of the injection molding machine is set according to the position state of the mold clamping device during its operation. A position sensor is installed on the mold clamping device. When the mold clamping device is in a preset position, the system receives a position signal and triggers the injection molding machine to enter the corresponding motion stage.

[0049] When the mold clamping device of the injection molding machine is in the initially set position and receives the position signal P0, the injection molding machine enters the pre-mold clamping stage in the mold clamping phase. In this stage, the servo motor provides driving force to control the mold clamping device to perform the mold clamping action. The hydraulic auxiliary device works in the oil replenishment mode. The cylinder control valve is open, the oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected, the buffer directional valve is open, the cylinder control valve and the oil outlet are connected, and the hydraulic oil output by the cylinder control valve is buffered and then output to the oil tank. The system outputs a relatively small pressure limit to the hydraulic pump in the hydraulic auxiliary device to replenish the hydraulic oil in the hydraulic auxiliary cylinder, so that the flow rate in the hydraulic auxiliary cylinder keeps up with the speed of the servo motor and is not pulled into a vacuum.

[0050] When the injection molding machine receives position signal P1, it enters the mold holding sub-stage of the mold closing process. In this stage, the molten plastic is injected into the mold cavity under high pressure. The injection molding machine continues to apply pressure to the mold closing device to compensate for the shrinkage during the plastic cooling process. Similarly, in this stage, the servo motor can provide sufficient force to the mold closing device. The hydraulic auxiliary device operates in oil replenishment mode. The cylinder control valve is open, the oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected, the buffer directional valve is open, and the cylinder control valve and the oil outlet are connected. The hydraulic oil output by the cylinder control valve is buffered and then output to the oil tank. The system control system limits the pressure and flow of the pump station. At this time, the torque of the servo motor is limited to the first set value of the mold holding force, and the pressure of the hydraulic auxiliary cylinder is limited to the second set value of the mold holding force. The hydraulic pump or oil reservoir in the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder.

[0051] When the injection molding machine receives position signal P2, it enters the high-pressure mold-locking sub-stage of the mold-closing phase. Since the distance between the start and end positions of this mold-locking stage is short, a momentary high pressure is required to complete this movement stage. The servo motor is suddenly accelerated to provide greater power, and at the same time, the hydraulic auxiliary device enters the power-assist mode. The cylinder control valve is turned on, the buffer directional valve is turned off, and the control oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected. This allows the rodless chamber to output the hydraulic oil output from the oil inlet to the rod chamber. The system outputs a relatively large pressure limit to the pump station. The hydraulic auxiliary device controls the hydraulic auxiliary cylinder to quickly pressurize and provide power to the mold-closing device, bearing part of the load, thereby reducing the burden on the servo motor.

[0052] In one embodiment, the operating mode further includes a mold-breaking mode; In the mold-breaking mode, the hydraulic auxiliary device provides a mold-breaking force to the mold-closing device.

[0053] The mold breaking occurs in the early stages of mold opening. The hydraulic auxiliary device helps the mold cavity and core to initially separate through specific actions or pressure settings. At this time, the hydraulic auxiliary device needs to enter the mold breaking mode. The cylinder control valve is turned on, the buffer directional valve is turned off, and the control oil inlet and the rod chamber of the hydraulic auxiliary cylinder are connected. This allows the rod chamber to output the hydraulic oil output from the oil inlet to the rodless chamber. At the same time, it controls the opening degree of the mold opening proportional valve and bears part of the mold opening force to assist the servo motor in opening the mold.

[0054] In this mode, the hydraulic auxiliary device applies an auxiliary breaking force to a certain part of the mold, creating a tiny gap between the mold cavity and the core. This reduces the burden on the servo motor during the initial mold opening stage, improves mold opening efficiency, and reduces wear caused by the tight fit of the mold. As the gap increases, the mold separation force gradually decreases until the breaking mode ends, entering the full mold opening stage.

[0055] In one embodiment, the mold-opening stage includes two sub-stages: mold breaking and final mold opening; During the mold-breaking sub-stage of the mold-opening stage, the hydraulic auxiliary device operates in mold-breaking mode; during the final mold-opening sub-stage of the mold-opening stage, the hydraulic auxiliary device operates in oil replenishment mode.

[0056] When the injection molding machine receives the position signal P3, it does not directly enter the mold opening stage, but triggers the mold pressing time. When the mold pressing time ends, the injection molding machine enters the mold opening stage, which includes two sub-stages: mold breaking and final mold opening.

[0057] During the mold-breaking sub-stage of the mold-opening process, the hydraulic auxiliary device operates in mold-breaking mode. The mold of the mold-closing device begins to separate initially under the drive of the servo motor. At this time, the hydraulic auxiliary device needs to control the opening of the mold-opening proportional valve to bear part of the mold-opening force and assist the servo motor in opening the mold. Because the mold experiences a momentary spring-off force during the mold-breaking stage, a thrust force in the opposite direction is needed to limit this spring-off force in order to protect the mold from being instantly ejected. The flow rate is controlled by the mold-opening proportional valve, reducing it. This causes the oil circuit to release pressure as needed, because the reduced flow rate accumulates at the pressure relief port, creating pressure – this pressure is the thrust force.

[0058] A mold opening proportional valve is a hydraulic component that continuously and proportionally controls the flow and pressure of hydraulic oil based on an input electrical signal. During the mold opening process, the control system sends corresponding electrical signals to the mold opening proportional valve according to a preset program and parameters to control its opening degree. By adjusting the opening degree of the mold opening proportional valve, the flow and pressure of the hydraulic oil can be precisely controlled, thereby achieving precise control of the mold opening force.

[0059] When the injection molding machine receives position signal P4, it enters the final mold opening sub-stage of the mold opening process. The servo motor continuously provides power, driving the mold closing device to further open the mold. The hydraulic auxiliary device operates in oil replenishment mode. The cylinder control valve is open, connecting the oil inlet and the rod chamber of the hydraulic auxiliary cylinder. The buffer directional valve is open, connecting the cylinder control valve and the oil outlet. The hydraulic oil output from the cylinder control valve is buffered and then output to the oil tank. The hydraulic pump or oil storage device within the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder. When the mold clamping device moves to the set position and triggers position signal P4, the injection molding machine receives position signal P4, the mold breaking motion is completed, the servo motor continues to provide power, pushing the mold clamping device to further open the mold, entering the fully open mold stage. At this time, the servo motor has sufficient driving force to control the action of the mold clamping device. The working state of the hydraulic auxiliary device switches from mold breaking mode to oil replenishment mode. The cylinder control valve is open, the oil inlet and the rod chamber of the hydraulic auxiliary cylinder are connected, the buffer directional valve is open, the cylinder control valve and the oil outlet are connected, and the hydraulic oil output by the cylinder control valve is buffered and output to the oil tank. The hydraulic auxiliary device controls its own hydraulic pump or oil storage device to replenish hydraulic oil to the hydraulic auxiliary cylinder to ensure stable system pressure and reserve hydraulic oil for the next stage.

[0060] It is worth noting that upon entering the mold opening stage, the hydraulic auxiliary device begins to push the piston and piston rod backward, thereby generating a driving force in the opposite direction. Therefore, during the mold opening stage, the oil inlet and the rod chamber of the hydraulic auxiliary cylinder are connected to control the retraction of the piston and piston rod.

[0061] In one embodiment, the mold opening and closing control method further includes the following steps: The torque of the servo motor is obtained during the mold closing or mold opening stage. When the injection molding machine is in the mold closing or mold opening stage, the control system will monitor the torque of the servo motor in real time. The torque data is collected by the sensor or the encoder built into the motor and transmitted to the control system.

[0062] When the servo motor's torque exceeds the preset torque, the hydraulic auxiliary device switches from replenishment mode to assist mode. When the motor's torque exceeds the preset torque, it usually means that the resistance of the mold or injection material to the motor has increased, indicating that the servo motor is currently under a high load. When the count reaches the preset value, it seems to indicate a sustained high load, meaning the servo motor has been under high load for a certain period. In this case, the hydraulic auxiliary device needs to switch from replenishment mode to assist the servo motor, thereby reducing its burden. Simultaneously, under high load conditions, hydraulic assistance ensures the smoothness and accuracy of the injection molding machine's operation, preventing system vibration or malfunctions caused by excessive load.

[0063] When the servo motor's torque is less than the preset torque, the hydraulic auxiliary device operates in oil replenishment mode. The fact that the servo motor's torque is less than the preset torque indicates that the servo motor is not under high load, and the power provided by the servo motor is sufficient for the mold clamping device to complete the current action.

[0064] This embodiment obtains the torque of the servo motor, thereby monitoring whether the servo motor is under high load, and switches the working state of the hydraulic auxiliary device to reduce the burden on the servo motor.

[0065] In one embodiment, after the hydraulic auxiliary device switches from the replenishment mode to the power assist mode, the method further includes: After the hydraulic auxiliary device operates in the power assist mode for a preset time, the torque of the servo motor is reacquired. After the hydraulic auxiliary device switches to the power assist mode, the system increases the flow rate of the hydraulic auxiliary cylinder and gives the servo motor a larger pressure limit. At this time, in order to maintain a constant mold closing force, the servo motor will rapidly reduce its torque until it reaches the maximum speed set by the motor.

[0066] When the servo motor torque exceeds a preset torque, the system determines to return to the replenishing oil mode until the current stage ends. If the servo motor torque meets the condition, the hydraulic auxiliary device returns from the assist mode to the replenishing oil mode. To reduce system errors caused by rapid switching of the hydraulic auxiliary device, a mode switching buffer time is added. During this time, the hydraulic system switches to assist mode, which continues until the buffer time ends. Afterward, the hydraulic auxiliary device will return to the replenishing oil mode again based on the actual motor torque.

[0067] In one embodiment, the mold opening and closing control method further includes: during the high-pressure mold locking sub-stage of the mold closing phase, the hydraulic auxiliary device operates in assist mode, and the operating mode of the hydraulic auxiliary device is independent of the torque of the servo motor. During the high-pressure mold locking sub-stage of the mold closing phase, the movement of this stage is triggered by a position signal P2. Since this stage requires the mold locking action, the hydraulic auxiliary device needs to provide a large auxiliary power. At this time, the hydraulic auxiliary system no longer uses the actual torque as the judgment basis and directly enters the assist mode, providing a large auxiliary power. Therefore, the operating mode of the hydraulic auxiliary device at this time is independent of the torque of the servo motor.

[0068] In one embodiment, the method further includes: In the pre-mold closing stage of the mold closing stage, the servo motor is controlled to accelerate to the set maximum speed, and after maintaining the set maximum speed for a set time, it decelerates to the first set speed. When the injection molding machine's mold clamping device is in the initially set position and receives the position signal P0, the injection molding machine enters the pre-mold clamping stage in the mold clamping phase. In this stage, the servo motor provides driving force to control the mold clamping device to perform the mold clamping action. The servo motor speed accelerates from 0. At this time, the hydraulic auxiliary device enters torque self-judgment based on the actual torque of the servo motor received by the controller. When the actual torque is less than the initially set motor torque limit, the hydraulic auxiliary device enters the oil replenishment mode. The cylinder control valve is opened, and the oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected. The buffer directional valve is opened, and the cylinder control valve and the oil outlet are connected. The hydraulic oil output by the cylinder control valve is buffered and then output to the oil tank. The system outputs a relatively small pressure limit to the hydraulic pump in the hydraulic auxiliary device to replenish the hydraulic oil in the hydraulic auxiliary cylinder until the flow rate and speed of the two cylinders are synchronized with the speed of the servo motor, so as not to create a vacuum.

[0069] As the servo motor speed increases, the actual servo motor torque gradually increases. If the actual motor torque does not exceed the set torque limit during the entire motion process, the hydraulic auxiliary device will assist the entire mold closing motion process in oil replenishment mode. When the actual torque exceeds the initial motor torque limit, the hydraulic auxiliary device enters the boost mode. In this mode, the hydraulic auxiliary device increases the flow rate in the cylinder, applying a larger pressure limit to the servo motor. To maintain a constant clamping force F, the motor reaches its preset maximum speed V1. At this point, the motor's speed / torque rapidly decreases. To reduce system errors caused by rapid mode switching in the hydraulic system, a mode switching buffer time is added. The hydraulic system switches to boost mode during this time, and this mode continues until the buffer time ends. Afterward, the hydraulic auxiliary device cycles back to the replenishment mode based on the actual motor torque. After running at the preset maximum speed V1 for a period of time, the servo motor decelerates to the set position P1 of the mold holding stage, at which point the speed is the first set speed V2.

[0070] During the mold holding stage in the mold closing stage, the servo motor is controlled to move at a constant speed at a first set speed. When the injection molding machine receives position signal P1, it enters the mold holding sub-stage of the mold closing phase. In this stage, the molten plastic is injected into the mold cavity under high pressure. The injection molding machine continues to apply pressure to the mold closing device to compensate for the shrinkage during the plastic cooling process. This process is a low-speed, uniform motion process, with the speed being the first set speed V2 set by the system. The motion cycle ends at the initial mold clamping position signal P2 set by the system. At this time, the hydraulic auxiliary device operates in oil replenishment mode to provide power because V2 is low, resulting in an actual torque lower than the set range. The hydraulic cylinder control valve is open, connecting the oil inlet and the rodless chamber of the hydraulic auxiliary cylinder. The buffer directional valve is open, connecting the hydraulic cylinder control valve and the oil outlet. The hydraulic oil output from the hydraulic cylinder control valve is buffered and then output to the oil tank. The system control system limits the pressure and flow rate of the pump station. At this time, the torque of the servo motor is limited to the first proportional value of the mold holding force, and the pressure of the hydraulic auxiliary cylinder is limited to the second proportional value of the mold holding force. The hydraulic pump or oil reservoir in the hydraulic auxiliary device replenishes hydraulic oil to the hydraulic auxiliary cylinder.

[0071] During the high-pressure mold-locking stage in the mold-closing stage, the servo motor is controlled to accelerate from a first set speed to a second set speed and then decelerate to 0. When the injection molding machine receives position signal P2, it enters the high-pressure clamping sub-stage of the mold closing phase. Because the distance between the starting and ending positions in this stage is short, a momentary high pressure is needed to complete this movement. This requires the servo motor to suddenly accelerate and provide significant power. The servo motor needs to suddenly accelerate from the first set speed V2 to the second set speed V3, and then decelerate to 0. At this time, the hydraulic auxiliary device no longer uses actual torque as the judgment criterion and directly enters the assist mode to provide a large auxiliary power. The cylinder control valve is activated, the buffer directional valve is deactivated, and the control oil inlet and the rodless chamber of the hydraulic auxiliary cylinder are connected. This allows the rodless chamber to output hydraulic oil from the inlet to the rod chamber. The system provides a relatively large pressure limit to the pump station, and the hydraulic auxiliary device controls the hydraulic auxiliary cylinder to quickly pressurize and provide power to the mold closing device, bearing part of the load and thus reducing the burden on the servo motor. Once the movement reaches position signal P3 and the speed drops to 0, it maintains a pressing time set by the system to ensure the integrity of the product molding.

[0072] During the mold breaking sub-stage of the mold opening stage, the servo motor is controlled to accelerate in the opposite direction to the third set speed. In the final mold-opening sub-stage of the mold-opening process, the servo motor is controlled to accelerate from a third set speed to a set maximum speed, and then maintain the set maximum speed for a set time before decelerating to 0.

[0073] When the injection molding machine receives position signal P3, it does not immediately enter the mold opening stage. Instead, it triggers the mold compression time. When the compression time ends, the injection molding machine enters the mold breaking sub-stage within the mold opening stage. It controls the servo motor to accelerate in the opposite direction to the third set speed V4. The mold of the mold closing device begins to separate initially under the drive of the servo motor. The system controls the opening of the mold opening proportional valve, and the hydraulic auxiliary device enters the mold breaking mode, bearing part of the mold opening force and assisting the servo motor in mold opening. When mold opening is complete and the mold breaking endpoint P4 is reached, the position signal triggers a movement that accelerates from the third set speed V4 to the set maximum speed V5, and then decelerates back to 0 after running at the set maximum speed V5 for a period of time. At this point, at the mold breaking endpoint P4, the hydraulic auxiliary device switches to oil replenishment mode to assist the motor in mold opening. At this time, the hydraulic auxiliary device operates in the same mode as in the mold closing stage. If the actual motor torque does not exceed the set torque limit during the entire movement, the hydraulic auxiliary device assists the entire mold opening movement in the oil replenishment mode. If the actual motor torque exceeds the set torque limit, the hydraulic auxiliary device switches from the oil replenishment mode during the acceleration process to the assist mode when the torque exceeds the limit. Since the assist provides a large force instantly, the motor torque will decrease instantly. To avoid the hydraulic auxiliary device switching between modes too quickly, a buffer period is set after entering the assist mode. After that, the hydraulic auxiliary device will cycle back to the oil replenishment mode according to the determination of the actual motor torque until it reaches the initial set position P0.

[0074] The present invention also proposes an opening and closing mold control system, comprising: Memory; The processor stores the mold opening and closing control program in memory and executes it. When the processor executes the mold opening and closing control program, it implements the mold opening and closing control method described above.

[0075] This invention also proposes an injection molding machine, including a servo motor, a hydraulic auxiliary device, a mold closing device, and an opening and closing control system as described above. The opening and closing control system switches the operating mode of the hydraulic auxiliary device according to different motion stages, and controls the operation of the hydraulic auxiliary device according to the determined operating mode. During non-critical stages of mold opening and closing, such as the initial startup or near the end point, the hydraulic auxiliary device automatically enters a replenishing oil mode. The hydraulic auxiliary device maintains or replenishes the oil pressure in the hydraulic system, ensuring that the hydraulic system can respond quickly when needed, while reducing unnecessary hydraulic energy consumption. During critical stages of mold opening and closing, such as rapid mold opening and closing or under heavy loads, the hydraulic auxiliary device quickly switches to an assist mode, providing strong hydraulic pressure to the mold closing device, ensuring that the injection molding machine can smoothly complete heavy-load operations while maintaining the smoothness and accuracy of movement.

[0076] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method of open-close die control, characterized by, The control method includes: The motion phase of the injection molding machine is obtained, and the servo motor is controlled to drive the mold clamping device to move. Based on the motion phase, the working mode of the hydraulic auxiliary device is determined, and the operation of the hydraulic auxiliary device is controlled according to the determined working mode; wherein, the working mode includes a replenishing oil mode and an assist mode, and in the replenishing oil mode, the hydraulic auxiliary device stores oil; In the power-assisted mode, the hydraulic auxiliary device provides assistance to the mold-closing device.

2. The mold opening and closing control method according to claim 1, characterized by, The motion phase includes the mold closing phase and the mold opening phase; During the mold closing stage, the hydraulic auxiliary device operates in either oil replenishment mode or power assist mode. During the mold opening stage, the hydraulic auxiliary device operates in oil replenishment mode.

3. The mold opening and closing control method according to claim 2, characterized by, The mold closing stage includes three sub-stages: pre-mold closing, mold protection, and high-pressure mold locking. During the pre-mold closing stage in the mold closing phase, the hydraulic auxiliary device operates in oil replenishment mode; During the mold protection stage in the mold closing stage, the hydraulic auxiliary device operates in oil replenishment mode; During the high-pressure locking stage of the mold closing phase, the hydraulic auxiliary device operates in assist mode.

4. The mold opening and closing control method according to claim 1, characterized by, The working mode also includes a mold-breaking mode; In the mold-breaking mode, the hydraulic auxiliary device provides a mold-breaking force to the mold-closing device.

5. The mold opening and closing control method according to claim 2, characterized by The mold-opening stage includes two sub-stages: mold breaking and final mold opening. During the mold-breaking sub-stage of the mold-opening stage, the hydraulic auxiliary device operates in mold-breaking mode; During the final mold-opening sub-stage of the mold-opening process, the hydraulic auxiliary device operates in oil replenishment mode.

6. The mold opening and closing control method according to claim 2, characterized by The mold opening and closing control method further includes the following steps: The torque of the servo motor is obtained during the mold closing or mold opening stage; When the torque of the servo motor is greater than the preset torque, the hydraulic auxiliary device switches from the oil replenishment mode to the power assist mode. When the torque of the servo motor does not meet the requirement of being greater than the preset torque, the hydraulic auxiliary device operates in the oil replenishment mode.

7. The mold opening and closing control method according to claim 6, characterized by, After the hydraulic auxiliary device switches from replenishment mode to power assist mode, the method further includes: After the hydraulic auxiliary device operates in the power assist mode for a preset time, the torque of the servo motor is reacquired. When the torque of the servo motor is greater than the preset torque, the system will determine to return to the oil replenishment mode in a loop until the current stage ends.

8. The mold opening and closing control method according to claim 6, characterized by, The mold opening and closing control method further includes: During the high-pressure mold-locking sub-stage of the mold-closing phase, the hydraulic auxiliary device operates in assist mode, and the operating mode of the hydraulic auxiliary device is independent of the torque of the servo motor.

9. A mold opening and closing control system characterized by comprising: include: Memory; A processor, a mold opening and closing control program stored in the memory and executed by the processor, wherein the mold opening and closing control program, when executed by the processor, implements the mold opening and closing control method as described in any one of claims 1-8.

10. An injection molding machine characterized by, It includes a servo motor, a hydraulic auxiliary device, a mold closing device, and the mold opening and closing control system as described in claim 9.

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