Hydraulic system of injection molding machine, control method, injection molding machine and storage medium

Abstract

The invention discloses a hydraulic system of an injection molding machine, a control method, the injection molding machine and a storage medium. Wherein the hydraulic system comprises an oil tank, an internal gear pump, an electromagnetic directional valve and an injection oil cylinder; an oil inlet of the internal gear pump is connected with the oil tank, an oil outlet of the internal gear pump is connected with an oil inlet of the electromagnetic directional valve, a main oil outlet of the electromagnetic directional valve is connected with the injection oil cylinder, and an auxiliary oil outlet of the electromagnetic directional valve is connected with the oil tank and used for being opened when the injection molding machine is in a pressure maintaining stage. And the rotating speed of the internal gear pump is kept stable. The hydraulic system not only can effectively reduce overflow loss and improve the energy efficiency of the whole system, but also can ensure that the rotating speed of the internal gear pump is kept stable and prevent the internal gear pump from being stuck, so that the internal gear pump always has certain oil absorption capacity, and the service life of the internal gear pump is prolonged. And the conditions of flow fluctuation of a hydraulic system, increase of operation noise and abnormal abrasion of a pump body caused by insufficient oil absorption are avoided.

Description

Technical Field

[0001] This application belongs to the field of injection molding machine control technology, and specifically relates to a hydraulic system, control method, injection molding machine, and storage medium for an injection molding machine. Background Technology

[0002] In parallel control molding and the production of thick-walled optical lenses, injection molding machines require a high-pressure, low-speed core molding process to ensure dimensional accuracy, consistency, and optical performance of the products. This process demands that the hydraulic system output stable high pressure while maintaining a low operating speed. The holding pressure stage of the injection molding machine, as a critical molding step, operates under extreme conditions of highest pressure and lowest speed, placing even more stringent requirements on the stability and oil suction capacity of the hydraulic system.

[0003] Currently, most injection molding machine hydraulic systems use internal gear pumps as their power core. However, these pumps face significant technical bottlenecks under high-pressure, low-speed conditions: reduced speed directly leads to insufficient vacuum in the suction chamber, making it difficult to overcome the increased viscosity and decreased fluidity of the oil under high pressure, resulting in insufficient suction resistance. This combination of factors easily leads to insufficient suction. Insufficient suction causes fluctuations in hydraulic system flow, increased operating noise, and abnormal pump wear. This not only reduces the efficiency and reliability of the hydraulic system but also directly affects the stability of injection molding, causing defects such as shrinkage cavities, bubbles, and weld lines in the products. It also makes it difficult to meet the high-precision synchronous requirements of parallel control molding and the high optical performance requirements of thick-walled optical lenses. The extreme conditions during the holding pressure stage further exacerbate this problem, with oil flow almost stagnating and pump lubrication and cooling conditions deteriorating, significantly increasing the risk of pump seizure.

[0004] Application content To address the aforementioned problems, this application discloses a hydraulic system, control method, injection molding machine, and storage medium for an injection molding machine, in order to overcome or at least partially solve the aforementioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application discloses a hydraulic system for an injection molding machine, the hydraulic system including an oil tank, an internal gear pump, a solenoid directional valve, and an injection cylinder; The inlet of the internal gear pump is connected to the oil tank, the outlet of the internal gear pump is connected to the inlet of the solenoid directional valve, the main outlet of the solenoid directional valve is connected to the injection cylinder, and the auxiliary outlet of the solenoid directional valve is connected to the oil tank. The auxiliary outlet of the solenoid directional valve is used to open when the injection molding machine is in the pressure holding stage to keep the speed of the internal gear pump stable.

[0006] Furthermore, the hydraulic system also includes a pressure sensor and a speed sensor; The pressure sensor is used to detect the oil pressure in the injection cylinder, and the speed sensor is used to detect the speed of the internal gear pump.

[0007] Furthermore, the hydraulic system also includes a proportional relief valve; The inlet of the proportional relief valve is connected to the pipeline between the internal gear pump and the solenoid directional valve, and the outlet of the proportional relief valve is connected to the oil tank. The proportional relief valve opens when the oil pressure in the injection cylinder is higher than a first pressure value and closes when the oil pressure in the injection cylinder is lower than a second pressure value.

[0008] Furthermore, the hydraulic system also includes an adjustable flow valve; The adjustable flow valve is connected between the oil tank and the internal gear pump, and the opening degree of the adjustable flow valve is inversely proportional to the rotational speed of the internal gear pump.

[0009] Furthermore, the electromagnetic reversing valve is integrated at the flange port of the internal gear pump.

[0010] This application also discloses a control method for the hydraulic system of an injection molding machine as described above, the control method comprising: According to the working stage of the injection molding machine, the internal meshing gear pump is controlled to pump the hydraulic oil in the oil tank into the injection cylinder through the main oil outlet of the electromagnetic reversing valve. When the oil pressure in the injection cylinder is higher than the preset upper limit of oil pressure and the rotation speed of the internal gear pump is lower than the preset speed, the opening of the electromagnetic reversing valve is controlled to open the auxiliary oil outlet of the electromagnetic reversing valve. Adjust the opening of the electromagnetic reversing valve to keep the rotational speed of the internal gear pump stable; When the oil pressure in the injection cylinder is lower than the preset lower limit of oil pressure, the opening of the electromagnetic reversing valve is controlled to close the auxiliary oil outlet.

[0011] Furthermore, the specific steps of adjusting the opening of the electromagnetic directional valve to maintain a stable rotational speed of the internal gear pump include: The opening of the electromagnetic reversing valve is adjusted according to the rotational speed of the internal gear pump and the oil pressure in the injection cylinder to keep the rotational speed of the internal gear pump stable.

[0012] Furthermore, the formula for calculating the opening degree of the electromagnetic directional valve is as follows: K=K p ·(pp 额 ) / n+K i ·∫(pp 额 )dt Where K is the opening degree of the electromagnetic directional valve, which is dimensionless; K p For proportional gain, dimensionless; K i p is the integral gain, dimensionless; p is the oil pressure in the injection cylinder, in bar; p 额 is the rated injection pressure of the injection cylinder, in bar; n is the rotational speed of the internal gear pump, in rpm.

[0013] This application further discloses an injection molding machine, said injection molding machine comprising: Processor; and Memory for storing the executable instructions of the processor; The processor executes the executable instructions to enable the injection molding machine to implement the control method described above.

[0014] The last aspect of this application discloses a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the control method described above.

[0015] The advantages and beneficial effects of this application are: In the hydraulic system of the injection molding machine of this application, an electromagnetic directional valve is installed between the internal gear pump and the injection cylinder. The main outlet of the electromagnetic directional valve is connected to the injection cylinder, and the auxiliary outlet is connected to the oil tank. The auxiliary outlet of the electromagnetic directional valve opens when the injection molding machine is in the holding pressure stage, unloading excess high-pressure oil back to the oil tank. This not only effectively reduces overflow loss and ineffective energy consumption, thereby improving the energy efficiency of the entire system, but also ensures that a certain amount of hydraulic oil always flows through the internal gear pump, maintaining a stable speed of the internal gear pump and preventing it from jamming. This gives the internal gear pump a certain oil suction capacity, avoiding the hydraulic system flow fluctuations, increased operating noise, and abnormal pump wear caused by insufficient oil suction. The hydraulic oil flow fluctuation is controlled within ±3%, significantly reducing batch-to-batch differences and surface shrinkage defects, increasing the product qualification rate from the original 95% to over 99%. Furthermore, this hydraulic system does not require an additional power source and has the advantages of fast response, low energy consumption, and compact structure. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the hydraulic system of an injection molding machine in one embodiment of this application; Figure 2This is a schematic diagram of the hydraulic system of an injection molding machine in one embodiment of this application; Figure 3 This is a schematic diagram of the hydraulic system of an injection molding machine in a preferred embodiment of this application; Figure 4 This is a diagram illustrating the implementation steps of a control method for the hydraulic system of an injection molding machine in another embodiment of this application; Figure 5 This is a schematic diagram of the structure of an injection molding machine in another embodiment of this application.

[0017] In the diagram: 1. Oil tank; 2. Internal gear pump; 3. Solenoid directional valve; 4. Injection cylinder; 5. Filter; 6. Drive motor; 7. Proportional relief valve. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0019] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or sets.

[0020] To keep the drawings concise, each drawing only schematically shows the parts relevant to this application, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of the components with the same structure or function is schematically drawn, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0021] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the specific implementation methods of this application will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without creative effort.

[0023] One embodiment of this application provides a hydraulic system for an injection molding machine, such as... Figure 1 and Figure 2 As shown, the hydraulic system includes an oil tank 1, an internal gear pump 2, a solenoid directional valve 3, an injection cylinder 4, and a drive motor 6. The oil tank 1 is used to store and supply hydraulic oil.

[0024] Specifically, the inlet of the internal gear pump 2 is connected to the oil tank 1 to draw hydraulic oil from the tank. The outlet of the internal gear pump 2 is connected to the inlet of the solenoid directional valve 3. The drive motor 6 is connected to the gear pump 2 to provide rotational driving force. The drive motor 6 is preferably a servo motor, which can achieve millisecond-level speed adjustment, accurately matching the speed requirements of high pressure and low speed, and pressure holding stages, avoiding the energy waste of fixed-speed motors. Furthermore, the smooth start-stop and speed regulation characteristics of the servo motor avoid the impact load during the start-stop of traditional motors, further reducing pump wear and the probability of jamming, and extending the overall system life. The main outlet of the solenoid directional valve 3 is connected to the injection cylinder 4, injecting hydraulic oil into the injection cylinder 4 through the main outlet. The auxiliary outlet of the solenoid directional valve 3 is connected to the oil tank 1 and is used to open when the injection molding machine is in the pressure holding stage, so that the speed of the internal gear pump 2 remains stable.

[0025] Understandably, during the pressure holding phase of the injection molding machine, the hydraulic system operates at its highest pressure and lowest speed, resulting in a very low oil volume required by the injection cylinder 4. This leads to extremely slow rotation speed of the internal gear pump 2, insufficient oil suction, large oil pressure fluctuations, and even pump jamming. In this embodiment, an electromagnetic directional valve 3 is installed between the internal gear pump 2 and the injection cylinder 4. The secondary outlet of the electromagnetic directional valve 3 opens during the pressure holding phase of the injection molding machine, allowing a portion of the hydraulic oil output by the internal gear pump 2 to drain into the oil tank 1 through the secondary outlet of the electromagnetic directional valve 3. This ensures that a certain amount of hydraulic oil always flows through the internal gear pump 2, thereby maintaining a stable rotation speed and preventing insufficient oil suction and pump jamming due to excessively low speed. This ensures continuous and stable operation of the hydraulic system and extends the overall system lifespan.

[0026] It should be noted that the main outlet of the solenoid directional valve 3 is always open. In addition, compared with the main outlet of the solenoid directional valve 3, the amount of hydraulic oil discharged from the auxiliary outlet of the solenoid directional valve 3 is smaller. When a small flow of pressure is released through the auxiliary outlet of the solenoid directional valve 3, it will not interfere with the oil pressure in the injection cylinder 4, so that the system continues to maintain high pressure.

[0027] In this embodiment, the hydraulic system also includes a pressure sensor and a speed sensor.

[0028] A pressure sensor is used to detect the oil pressure inside the injection cylinder 4, and a speed sensor is used to detect the speed of the internal gear pump 2. This allows for the adjustment of the opening degree of the solenoid directional valve 3 based on the oil pressure inside the injection cylinder 4 and the speed of the internal gear pump 2, thereby controlling the amount of oil discharged through the auxiliary outlet of the solenoid directional valve 3, compensating for pressure fluctuations, and keeping the oil pressure inside the injection cylinder 4 stable.

[0029] Furthermore, the electromagnetic directional valve 3 is integrated into the flange of the internal gear pump 2, allowing the oil outlet of the internal gear pump 2 to be directly connected to the oil inlet of the directional valve through an internal flow channel. This eliminates the need for external piping connections, reducing external pipelines and joints, and consequently reducing leakage problems caused by pipeline wear, loosening, or seal failure, thus improving the system's sealing performance and reliability. Simultaneously, the integrated design makes maintenance more convenient; during inspection and repair, only the integrated module needs to be monitored, eliminating the need to individually check numerous pipelines and valves, reducing maintenance costs and time.

[0030] In addition, such as Figure 1 and Figure 2 As shown, the hydraulic system also includes a filter 5.

[0031] Specifically, filter 5 is connected between oil tank 1 and internal gear pump 2 to filter impurities such as metal particles, dust, and rubber debris from production, wear, or external sources in the oil, preventing impurities from clogging valve ports, scratching pump gears / bearings, or damaging seals, and reducing hydraulic system pressure / flow fluctuations caused by oil contamination.

[0032] In a preferred embodiment of this application, such as Figure 3 As shown, the hydraulic system also includes a proportional relief valve 7.

[0033] The inlet of the proportional relief valve 7 is connected to the pipeline between the internal gear pump 2 and the solenoid directional valve 3, and the outlet of the proportional relief valve 7 is connected to the oil tank 1, forming a parallel connection with the solenoid directional valve 3. The proportional relief valve 7 opens when the oil pressure in the injection cylinder 4 is higher than a first pressure value, and closes when the oil pressure in the injection cylinder 4 is lower than a second pressure value. The first and second pressure values ​​are determined based on the required holding pressure provided by the injection cylinder 4, with the first pressure value being greater than the second pressure value, and the difference between the two being 0.2 Pascals (Pa).

[0034] Understandably, the pressure sensor monitors the oil pressure in injection cylinder 4 in real time. When the oil pressure in injection cylinder 4 is higher than the first pressure value, the proportional relief valve 7 is opened, allowing some hydraulic oil to flow back to the oil tank 1, thus reducing the flow of hydraulic oil into the solenoid directional valve 3. When the oil pressure in injection cylinder 4 is lower than the second pressure value, the proportional relief valve 7 is closed, reducing the diversion of hydraulic oil and allowing more hydraulic oil to enter the solenoid directional valve 3. When the pressure fluctuates, the proportional relief valve 7 opens or closes rapidly to divert or replenish the flow of hydraulic oil, thereby smoothing the pressure. The proportional relief valve 7 works in conjunction with the solenoid directional valve 3: the solenoid valve handles macroscopic flow distribution, while the proportional relief valve 7 handles microscopic pressure fluctuations, forming a dual protection for stable flow, replenishing pressure fluctuations, and improving system stability. The opening and closing of the proportional relief valve 7 is a single process, making oil pressure changes smoother and avoiding oil pressure fluctuations caused by sudden opening and closing of the relief valve.

[0035] It should be noted that the proportional relief valve 7 and the solenoid directional valve 3 are electrically connected to the same controller, which simultaneously controls both the proportional relief valve 7 and the solenoid directional valve 3. When a pressure sensor signal is input to the controller, the controller outputs two signals: one to control the opening degree of the solenoid directional valve 3, and the other to control the opening degree of the proportional relief valve 7.

[0036] In other embodiments of this application, the hydraulic system further includes an adjustable flow valve.

[0037] An adjustable flow valve is connected between the oil tank and the internal gear pump. The opening degree of the adjustable flow valve is inversely proportional to the speed of the internal gear pump.

[0038] Understandably, when the pump is running at low speed (such as during high-pressure molding and pressure holding stages), the valve opening automatically increases to increase the oil suction flow and compensate for insufficient vacuum in the oil suction chamber; when the pump speed increases, the valve opening decreases synchronously to avoid excessive oil suction, which could lead to oil turbulence or pressure fluctuations and ensure system stability.

[0039] Another embodiment of this application provides a control method for the hydraulic system of the injection molding machine described in the above embodiments, such as... Figure 4 As shown, the control method includes: Step 01: According to the working stage of the injection molding machine, control the internal gear pump to pump the hydraulic oil in the oil tank into the injection cylinder through the main oil outlet of the electromagnetic reversing valve.

[0040] Specifically, the system obtains the working stage of the injection molding machine. First, the system identifies the current working stage through the injection molding machine's controller (determined by feedback signals from the screw position sensor and pressure sensor). Then, based on the pressure / flow requirements of different working stages of the injection molding machine (injection, holding pressure, cooling, etc.), it achieves precise delivery of hydraulic oil to provide stable power for the molding process. During the standby, mold closing, sol-gel, and mold opening stages, the internal gear pump remains in standby mode and does not pump hydraulic oil into the injection cylinder, thus saving energy and protecting the pump. During the injection stage, the controller sends a speed control signal to the servo motor, driving the internal gear pump to start and put it into operation. The main outlet of the electromagnetic directional valve is fully open, while the secondary outlet remains closed, ensuring that hydraulic oil is directly pumped into the injection cylinder through the internal integrated flow channel without flow diversion loss, driving the injection cylinder pump. During injection, the flow rate at the main outlet can be monitored in real time by a flow sensor, and feedback is sent to the controller for fine-tuning to ensure that the flow rate matches the current operating conditions (e.g., flow rate ≥ 50 L / min during injection, flow rate ≤ 10 L / min during pressure holding). This achieves precise matching of operating conditions and flow rate, avoiding the energy waste caused by the "one-size-fits-all" delivery of traditional systems, and laying the foundation for pressure regulation in the subsequent pressure holding stage.

[0041] Step 02: When the oil pressure in the injection cylinder is higher than the preset upper limit of oil pressure and the speed of the internal gear pump is lower than the preset speed, control the opening of the solenoid directional valve to open the secondary oil outlet of the solenoid directional valve.

[0042] Specifically, based on the molding process requirements of injection-molded products (such as thick-walled optical lenses), a preset upper limit for oil pressure (e.g., 15MPa, corresponding to the highest pressure requirement during the holding stage) and a preset speed (e.g., 100rpm, the minimum stable speed of the pump under high-pressure conditions) are set in the controller. Oil pressure data within the injection cylinder is collected by a pressure sensor built into the injection cylinder, and the real-time speed of the internal gear pump is detected by a speed sensor, or by a speed encoder of the servo motor. The data sampling frequency is ≥10Hz to ensure timely response. When the controller simultaneously detects that "detected oil pressure > preset upper limit for oil pressure" and "pump detected speed < preset speed," it determines that the system has entered a high-pressure, low-speed condition (e.g., the holding stage). At this time, the vacuum in the oil suction chamber is insufficient, and an opening command for the secondary oil outlet is immediately triggered. After receiving the command, the electromagnetic reversing valve completes the opening action of the secondary oil outlet within 50ms, maintaining a minimum opening degree (e.g., 10%) during the initial opening to avoid a sudden pressure drop. This process can accurately capture extreme operating conditions and unload high-pressure oil by opening the auxiliary oil outlet. This reduces overflow losses and indirectly replenishes the pressure in the suction chamber through oil return, preventing pump jamming due to insufficient vacuum in the suction chamber and ensuring the normal operation of the internal gear pump. The preset upper limit of oil pressure and preset speed are determined according to the actual production scenario.

[0043] It should be noted that: Q 主 =Q 泵 ·(1-K),Q 副 =Q 泵 -Q 主 .

[0044] Among them, Q 主 Q is the main oil port flow rate of the solenoid directional valve; 副 Q represents the auxiliary oil port flow rate of the solenoid directional valve; 泵 is the output flow rate of the internal gear pump; K is the opening degree of the solenoid directional valve, with a value range of 0~30%.

[0045] Step 03: Adjust the opening of the solenoid directional valve to keep the speed of the internal gear pump stable.

[0046] Specifically, if the speed of the internal gear pump continues to decrease, it indicates that the pump load is too high, and the unloading amount needs to be increased. For example, the opening degree of the solenoid directional valve can be increased by 5% every 5ms until the speed returns to within ±2 rpm of the target value. If the speed of the internal gear pump continues to increase, it indicates that excessive unloading has led to an insufficient pump load, and the opening degree needs to be reduced. For example, the opening degree of the solenoid directional valve can be reduced by 3% every 5ms to avoid excessive speed fluctuations. In this process, closed-loop control achieves dynamic adaptive adjustment, avoiding the lag of manual adjustment, ensuring that the hydraulic oil flow fluctuation is controlled within ±3%, significantly reducing batch-to-batch differences and surface shrinkage defects, and increasing the product qualification rate from the original 95% to over 99%.

[0047] Step 04: When the oil pressure in the injection cylinder is lower than the preset lower limit of oil pressure, control the opening of the solenoid directional valve to close the auxiliary oil outlet.

[0048] Specifically, if the oil pressure in the injection cylinder is lower than the preset lower oil pressure limit (e.g., 8 MPa) for a duration of ≥1 second (excluding false pressure fluctuations), the controller determines that the pressure holding phase has ended, the system exits the high-pressure, low-speed operating condition, and sends a closing command to the solenoid directional valve. Upon receiving the closing command, the solenoid directional valve completes the closing action of the auxiliary oil outlet within 30 ms. During the closing process, a gradual closing is adopted (reducing the opening degree by 20% every 10 ms) to avoid oil circuit pressure surges. The preset lower oil pressure limit is determined based on the actual production scenario.

[0049] In this embodiment, adjusting the opening of the electromagnetic reversing valve to maintain a stable rotational speed of the internal gear pump specifically includes: The opening of the solenoid directional valve is adjusted according to the rotational speed of the internal gear pump and the oil pressure in the injection cylinder to keep the rotational speed of the internal gear pump stable.

[0050] The detailed formula for calculating the opening degree of the solenoid directional valve is as follows: K=K p ·(pp 额 ) / n+K i ·∫(pp 额 )dt Where K is the opening degree of the solenoid directional valve, which is dimensionless; K p For proportional gain, dimensionless; K i p is the integral gain, dimensionless; p is the oil pressure in the injection cylinder, in bar; p 额 K represents the rated injection pressure of the injection cylinder, in bar; n represents the rotational speed of the internal gear pump, in rpm. It should be noted that K... p (Proportional gain) and K i (Integral gain) needs to be determined during the machine debugging phase based on the system's dynamic characteristics (such as response speed and stability). Too large a gain will lead to overshoot or oscillation, while too small a gain will result in a slow response. P (oil pressure in the injection cylinder) and n (speed of the internal gear pump) are real-time measured values.

[0051] In another embodiment of this application, an injection molding machine is provided, such as... Figure 5 As shown, the injection molding machine includes: One or more processors (or processing units); may also include one or more memories coupled to the processor for storing executable instructions of the processor, and may also include a communication module coupled to the processor. The processor executes the executable instructions to cause the injection molding machine to implement the control method of the hydraulic system of the injection molding machine as described in the foregoing embodiments.

[0052] A communication module can be used to communicate with other devices or apparatuses, such as sending or receiving data and / or signals. A communication module may have at least one communication module for communication. A communication module may include any interface necessary for communicating with other devices. Exemplarily, a communication module may be a transceiver, circuit, bus, module, or other type of communication module.

[0053] The processor may include, but is not limited to, one or more of the following: a general-purpose computer, a special-purpose computer, a microcontroller, a digital signal processor (DSP), or a controller-based multi-core controller architecture. The device may have multiple processors, such as application-specific integrated circuit (ASIC) chips, which are time-dependent on a clock synchronized with the main processor.

[0054] The memory may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, at least one of the following: read-only memory (ROM), electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disc (DVD), or other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, at least one of the following: random access memory (RAM), or other volatile memories that do not persist during the duration of a power outage.

[0055] A computer program consists of computer-executable instructions that are executed by an associated processor. Programs can be stored in ROM. A processor can perform any appropriate action and processing by loading the program into RAM.

[0056] Possible implementations of this application can be achieved through a program, enabling the communication device to execute any of the processes discussed in the foregoing embodiments. Possible implementations of this application can also be achieved through hardware or a combination of software and hardware.

[0057] In some implementations, the program may be tangibly contained in a computer-readable storage medium, which may include in a device (such as in memory) or other storage device accessible by the device. The program may be loaded from the computer-readable storage medium into RAM for execution. The computer-readable storage medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc.

[0058] The last aspect of this application discloses a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the control method described above.

[0059] Embodiments of this application also provide a computer-readable storage medium having computer instructions or program code stored thereon, which, when executed by a processor, cause the processor to perform the methods and functions involved in any of the above embodiments. The computer-readable medium can be any tangible medium that contains or stores a program for or relating to an instruction execution system, apparatus, or device. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. More detailed examples of computer-readable storage media include electrical connections with one or more wires, magnetic media (e.g., disks, floppy disks, hard disks, magnetic tapes, magnetic storage devices), optical media (e.g., optical storage devices, DVDs), semiconductor media (e.g., solid-state drives), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), or any suitable combination thereof.

[0060] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. Embodiments of this application also provide at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. This computer program product includes one or more computer-executable instructions, such as instructions included in a program module, which execute in a device on a target's real or virtual processor to perform the processes, methods, and functions involved in any of the above embodiments. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means.

[0061] Embodiments of this application also propose a computer program product, including a computer program or instructions that, when run on a computer, cause the computer to perform the processes, methods, and functions described in the above embodiments. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided as needed. Machine-executable instructions for program modules can be executed locally or in a distributed device. In a distributed device, program modules can reside in both local and remote storage media.

[0062] Generally, the various embodiments of this application can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while others can be implemented in firmware or software, which can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments disclosed in this application are shown and described as block diagrams, flowcharts, or represented using some other illustration, it should be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented as, as non-limiting examples, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0063] In the hydraulic system of the injection molding machine of this application, an electromagnetic directional valve is installed between the internal gear pump and the injection cylinder. The main outlet of the electromagnetic directional valve is connected to the injection cylinder, and the auxiliary outlet is connected to the oil tank. The auxiliary outlet of the electromagnetic directional valve opens when the injection molding machine is in the holding pressure stage, unloading excess high-pressure oil back to the oil tank. This not only effectively reduces overflow loss and ineffective energy consumption, thereby improving the energy efficiency of the entire system, but also ensures that a certain amount of hydraulic oil always flows through the internal gear pump, maintaining a stable speed of the internal gear pump and preventing it from jamming. This gives the internal gear pump a certain oil suction capacity, avoiding the hydraulic system flow fluctuations, increased operating noise, and abnormal pump wear caused by insufficient oil suction. The hydraulic oil flow fluctuation is controlled within ±3%, significantly reducing batch-to-batch differences and surface shrinkage defects, increasing the product qualification rate from the original 95% to over 99%. Furthermore, this hydraulic system does not require an additional power source and has the advantages of fast response, low energy consumption, and compact structure.

[0064] The above description is merely a specific embodiment of this application. Under the guidance of the above teachings, those skilled in the art can make other improvements or modifications based on the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of this application, and the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hydraulic system for an injection molding machine, characterized by, The hydraulic system comprises an oil tank, an internal gear pump, an electromagnetic reversing valve and an injection cylinder; An oil inlet of the internal gear pump is connected with the oil tank, an oil outlet of the internal gear pump is connected with an inlet of the electromagnetic reversing valve, a main oil outlet of the electromagnetic reversing valve is connected with the injection cylinder, a secondary oil outlet of the electromagnetic reversing valve is connected with the oil tank, and the secondary oil outlet of the electromagnetic reversing valve is used to be opened when the injection molding machine is in a pressure maintaining stage, so that the rotating speed of the internal gear pump is maintained stable.

2. The hydraulic system of an injection molding machine according to claim 1, wherein, The hydraulic system further comprises a pressure sensor and a rotating speed sensor; The pressure sensor is used to detect the oil pressure in the injection cylinder, and the rotating speed sensor is used to detect the rotating speed of the internal gear pump.

3. The hydraulic system of an injection molding machine according to claim 2, wherein, The hydraulic system further comprises a proportional overflow valve; An oil inlet of the proportional overflow valve is connected with a pipeline between the internal gear pump and the electromagnetic reversing valve, an oil outlet of the proportional overflow valve is connected with the oil tank, and the proportional overflow valve is opened when the oil pressure in the injection cylinder is higher than a first pressure value, and is closed when the oil pressure in the injection cylinder is lower than a second pressure value.

4. The hydraulic system of an injection molding machine according to claim 1, wherein The hydraulic system further comprises an adjustable flow valve; The adjustable flow valve is connected between the oil tank and the internal gear pump, and the opening degree of the adjustable flow valve is inversely proportional to the rotating speed of the internal gear pump.

5. The hydraulic system of an injection molding machine according to claim 1, wherein, The electromagnetic reversing valve is integrated at a flange port of the internal gear pump.

6. A control method for a hydraulic system of an injection molding machine as defined in claim 1, characterized in that, The control method comprises: controlling the internal gear pump to pump hydraulic oil in the oil tank into the injection cylinder through the main oil outlet of the electromagnetic reversing valve according to the working stage of the injection molding machine; controlling the opening degree of the electromagnetic reversing valve when the oil pressure in the injection cylinder is higher than a preset upper limit of oil pressure and the rotating speed of the internal gear pump is lower than a preset rotating speed, so that the secondary oil outlet of the electromagnetic reversing valve is opened; adjusting the opening degree of the electromagnetic reversing valve to maintain the rotating speed of the internal gear pump stable; controlling the opening degree of the electromagnetic reversing valve when the oil pressure in the injection cylinder is lower than a preset lower limit of oil pressure, so that the secondary oil outlet is closed.

7. The control method according to claim 6, characterized by The adjusting of the opening degree of the electromagnetic reversing valve to maintain the rotating speed of the internal gear pump stable specifically comprises: adjusting the opening degree of the electromagnetic reversing valve according to the rotating speed of the internal gear pump and the oil pressure in the injection cylinder, so that the rotating speed of the internal gear pump is maintained stable.

8. The control method according to claim 7, characterized by, The calculation formula of the opening degree of the electromagnetic reversing valve is as follows: K = K p • (p - p 额 ) / n + K i • ∫(p - p 额 )dt wherein K is an opening degree of the electromagnetic directional control valve, dimensionless; K p is a proportional gain, dimensionless; K i is an integral gain, dimensionless; p is an oil pressure in the injection cylinder, bar; p 额 is a rated injection pressure of the injection cylinder, bar; n is a rotational speed of the internal gear pump, rpm.

9. An injection molding machine characterized by, The injection molding machine comprises: a processor; and a memory for storing executable instructions of the processor; wherein the processor executes the executable instructions to enable the injection molding machine to implement the control method according to any one of claims 6 to 8.

10. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, The computer program / instructions are executed by the processor to implement the control method according to any one of claims 6 to 8.

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