A hydraulic control unit, a servo control mold locking hydraulic system and an injection molding machine

Abstract

The application belongs to the technical field of hydraulic control systems of injection molding machines, and provides a hydraulic control unit, a servo control mold locking hydraulic system and an injection molding machine. The control unit comprises a high-frequency response servo valve, a one-way poppet valve, a two-way poppet valve and a controller. One end of the two-way poppet valve is connected to the rod cavity of a mold locking oil cylinder, and the other end is connected to a system oil tank. The controller is electrically connected to the high-frequency response servo valve, and is signal connected to a pressure sensor and a displacement sensor respectively. Compared with the prior art, the application integrates a high-frequency response servo valve, a one-way poppet valve, a two-way poppet valve and a closed-loop sensor controller to construct a high-precision hydraulic control unit, significantly improves the position repeatability and dynamic response speed of micro-opening actions, effectively meets the demand of advanced processes such as foaming injection molding and thin-wall molding for dynamic pressure adjustment of a mold cavity, and avoids problems such as uneven density of products, flash or mold damage.

Description

Technical Field

[0001] This invention belongs to the technical field of hydraulic control systems for injection molding machines, specifically relating to a hydraulic control unit, a servo-controlled clamping hydraulic system, and an injection molding machine. Background Technology

[0002] Injection molding is one of the most critical processes in plastic product manufacturing, and its molding quality highly depends on the stability and control precision of the clamping system. In traditional hydraulic injection molding machines, the clamping action is typically accomplished by a main hydraulic cylinder in conjunction with multiple sets of solenoid directional valves, cartridge valves, and relief valves to perform basic functions such as mold closing, clamping, opening, and pressure relief. However, as the requirements for molding precision and consistency continue to increase for high-value-added products (such as large appliance housings, automotive structural foam parts, and precision thin-walled parts), traditional clamping systems have shown significant shortcomings in terms of dynamic responsiveness, micro-displacement control capabilities, and energy efficiency.

[0003] Especially in advanced processes such as foam injection molding, structural foaming, or two-color co-injection, the melt expands in volume during the holding pressure stage. If the mold cavity is completely rigidly closed, the pressure inside the cavity will rise sharply, causing problems such as uneven product density, surface shrinkage marks, flash, and even mold damage. To alleviate this phenomenon, the industry has gradually introduced "mold plate micro-opening" technology—that is, during the holding pressure stage, the moving or fixed mold plate will produce a controllable micro-displacement at the sub-millimeter level (usually 0.1mm to 5mm) to dynamically adjust the cavity volume and release excess pressure. However, existing implementation methods mostly rely on additional auxiliary hydraulic cylinders or mechanical fine-tuning mechanisms, which are not only complex in structure and occupy a large space, but also difficult to achieve high-precision coordinated control with the main mold clamping system.

[0004] Furthermore, traditional hydraulic clamping circuits generally employ on / off solenoid valve combinations, resulting in coarse control logic that fails to achieve closed-loop linkage of position, pressure, and speed. Even when proportional valves are introduced in some equipment, their low response frequency (typically below 100Hz) and limited control resolution make it difficult to meet the requirements of 0.1mm repeatability and millisecond-level dynamic response for micro-opening actions. Simultaneously, to achieve switching between multiple operating conditions such as clamping, micro-opening, and pressure relief, existing systems often require 7 to 12 hydraulic components, leading to bulky hydraulic stations, complex piping, high leakage risk, limited mean time between failures (MTBF), and high maintenance costs.

[0005] Although servo drive technology has been applied in some high-end injection molding machines, it mainly focuses on all-electric or electro-hydraulic hybrid drives. A solution integrating a high-frequency response servo valve into a pure hydraulic clamping system to achieve micro-opening functionality remains undeveloped. In particular, there is a lack of a compact hydraulic control unit that can support conventional clamping / opening / closing actions, precisely execute sub-millimeter-level micro-opening through the same hydraulic circuit structure, and possess pressure-position dual closed-loop feedback capabilities.

[0006] Therefore, there is an urgent need to develop a servo-controlled clamping hydraulic system with a simplified structure, rapid response, and precise control. This system can efficiently achieve the micro-opening function of the mold plate without changing the mechanical architecture of the host machine, thereby improving the product molding quality and reducing energy consumption and maintenance difficulty. This will meet the urgent needs of industries such as home appliances and auto parts for high-precision and high-efficiency injection molding equipment. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a hydraulic control unit, a servo-controlled clamping hydraulic system and an injection molding machine, in light of the current state of the prior art.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a hydraulic control unit is proposed for controlling the action of the mold clamping cylinder, the control unit comprising:

[0009] High-frequency response servo valves, one-way lifting valves, two-way lifting valves, and controllers;

[0010] The high-frequency response servo valve is provided with an oil inlet P, a first working oil port A, a second working oil port B, and an oil return port T;

[0011] The oil inlet P is connected to the system pressure oil source, the first working oil port A is connected to the rod chamber of the mold locking cylinder through the one-way lifting valve, the second working oil port B is connected to the rodless chamber of the mold locking cylinder, and the oil return port T is connected to the system oil tank.

[0012] One end of the bidirectional lifting valve is connected to the rod chamber of the mold-locking cylinder, and the other end is connected to the system oil tank. The bidirectional lifting valve and the one-way lifting valve are connected in parallel in the oil circuit.

[0013] The controller is electrically connected to the high-frequency response servo valve and signal-connected to the pressure sensor and the displacement sensor respectively; the pressure sensor is used to monitor the oil pressure in the rod chamber or rodless chamber of the mold-locking cylinder in real time, and the displacement sensor is used to monitor the position of the piston rod of the mold-locking cylinder in real time.

[0014] When the template micro-opening action is performed, the controller drives the high-frequency response servo valve to switch to the micro-opening control position according to the feedback signals of the pressure sensor and the displacement sensor. This allows the pressure oil to enter the rodless chamber of the mold-locking cylinder through the second working oil port B. At the same time, the oil in the rod chamber of the mold-locking cylinder flows back to the system oil tank through the one-way lifting valve, the first working oil port A, and the return oil port T in sequence, thereby driving the piston rod to produce a micro-displacement of 0.1 mm to 5 mm.

[0015] The aforementioned hydraulic control unit also includes a one-way valve, which is located at the oil inlet of the system oil tank and allows oil to flow back to the system oil tank in one direction.

[0016] In addition to solving the above-mentioned technical problems, the present invention also proposes a servo-controlled mold-locking hydraulic system, including four sets of the above-mentioned hydraulic control units, the four sets of hydraulic control units are arranged in parallel, and the oil inlet P of each high-frequency response servo valve is connected to the system pressure oil source.

[0017] In the aforementioned servo-controlled mold-locking hydraulic system, the high-frequency response servo valve further includes a mold-opening control position and a mold-closing control position;

[0018] When the high-frequency response servo valve is in the mold opening control position, the pressure oil enters the rodless chamber of the mold locking cylinder through the second working oil port B. At the same time, part of the oil in the rod chamber of the mold locking cylinder flows back to the system oil tank through the one-way lifting valve, the first working oil port A and the return oil port T in sequence, and the other part flows back to the system oil tank through the two-way lifting valve, so as to drive the moving template to move away from the fixed template.

[0019] When the high-frequency response servo valve is in the mold closing control position, the pressure oil enters the rod chamber of the mold locking cylinder through the first working oil port A, while the oil in the rodless chamber of the mold locking cylinder flows back to the system oil tank through the second working oil port B and the return oil port T, thereby driving the moving mold plate to move towards the fixed mold plate.

[0020] In the aforementioned servo-controlled mold-locking hydraulic system, when the high-frequency response servo valve is in the mold-closing control position and the pressure in the rod chamber of the mold-locking cylinder reaches a preset value, the one-way lifting valve is energized and locked, so that the pressure oil is sealed in the rod chamber of the mold-locking cylinder, thereby maintaining the high-pressure mold-locking state.

[0021] In the aforementioned servo-controlled mold-locking hydraulic system, after the mold fixed on the fixed template and the moving template has finished feeding, the bidirectional lifting valve is energized, allowing the oil in the rod chamber of the mold-locking cylinder to flow to the system oil tank through the bidirectional lifting valve, thus putting the mold-locking cylinder in a depressurized state.

[0022] In addition to solving the above-mentioned technical problems, the present invention also proposes an injection molding machine, including the aforementioned servo-controlled clamping hydraulic system.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) A high-precision hydraulic control unit was constructed by integrating a high-frequency response servo valve, a one-way lifting valve, a two-way lifting valve, and a closed-loop sensor controller. During the micro-opening action of the mold plate, this unit utilizes the precise flow regulation capability of the high-frequency response servo valve, combined with real-time feedback from pressure and displacement sensors, to achieve closed-loop control of the sub-millimeter-level micro-displacement of the piston rod of the mold-locking cylinder within the range of 0.1mm to 5mm. Compared with traditional on / off valve systems, this significantly improves the position repeatability accuracy (up to ±0.1mm) and dynamic response speed of the micro-opening action (servo valve response frequency not less than 500Hz), effectively meeting the needs of advanced processes such as foam injection molding and thin-wall molding for dynamic adjustment of cavity pressure, and avoiding problems such as uneven density, flash, or mold damage in the product. Simultaneously, this structure simplifies the control logic and hydraulic circuit, providing basic unit support for high-precision, high-reliability mold-locking control.

[0025] (2) By applying four sets of hydraulic control units in parallel to the mold clamping system of the injection molding machine, a unified system of multi-cylinder synchronous drive and independent control is achieved. Each unit shares the same pressure oil source, resulting in a compact structure and simple piping. This ensures that the four corners of large injection molding machines (such as four-link structures) are subjected to uniform force during mold closing, mold clamping, and micro-opening processes. Furthermore, the controller allows for differentiated fine-tuning of each unit to adapt to complex process requirements such as mold deformation compensation and dual-color co-injection. This parallel system not only improves the overall rigidity of the machine but also significantly reduces the number of hydraulic components required by traditional solutions (by 7 to 12), reducing the volume of the hydraulic station by approximately 40%, effectively lowering manufacturing costs and maintenance difficulty.

[0026] (3) By precisely switching between the mold opening control position and the mold closing control position using a high-frequency response servo valve, bidirectional and efficient driving of the moving mold plate is achieved: oil enters the rodless cavity and returns oil to the rod cavity during mold opening, and vice versa during mold closing. This oil circuit logic makes full use of the bidirectional controllability of the servo valve, eliminating the need for multiple directional valves in traditional systems and simplifying the oil circuit structure; at the same time, since the entire process is controlled by the same servo valve, the speed, acceleration, and endpoint position of the mold opening and closing actions can all be programmably adjusted, supporting smooth switching of multiple speeds within the range of 0 to 500 mm / s, meeting the customized needs of complex molds for motion curves, and improving molding efficiency and product consistency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a hydraulic control unit according to the present invention.

[0028] Figure 2 This is a schematic diagram of a servo-controlled mold-locking hydraulic system according to the present invention.

[0029] In the diagram, 100 is the mold-locking cylinder; 110 is the rod chamber; 120 is the rodless chamber; 200 is the high-frequency response servo valve; 300 is the one-way lifting valve; 400 is the two-way lifting valve; 500 is the one-way valve; and 600 is the system oil tank. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0031] 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.

[0032] like Figure 1 As shown, the present invention provides a hydraulic control unit for controlling the movement of a mold-locking cylinder 100. The hydraulic control unit includes a high-frequency response servo valve 200, a one-way lifting valve 300, a two-way lifting valve 400, and a controller.

[0033] Specifically, the high-frequency response servo valve 200 is provided with an oil inlet P, a first working oil port A, a second working oil port B, and an oil return port T;

[0034] The oil inlet P is connected to the system pressure oil source, the first working oil port A is connected to the rod chamber 110 of the mold locking cylinder 100 through the one-way lifting valve 300, the second working oil port B is connected to the rodless chamber 120 of the mold locking cylinder 100, and the oil return port T is connected to the system oil tank 600.

[0035] One end of the bidirectional lifting valve 400 is connected to the rod chamber 110 of the mold-locking cylinder 100, and the other end is connected to the system oil tank 600. The bidirectional lifting valve 400 and the one-way lifting valve 300 are connected in parallel in the oil circuit.

[0036] The controller is electrically connected to the high-frequency response servo valve 200 and is signal-connected to the pressure sensor and the displacement sensor respectively; the pressure sensor is used to monitor the oil pressure in the rod chamber 110 or rodless chamber 120 of the mold clamping cylinder 100 in real time, and the displacement sensor is used to monitor the position of the piston rod of the mold clamping cylinder 100 in real time.

[0037] When the template micro-opening action is performed, the controller drives the high-frequency response servo valve 200 to switch to the micro-opening control position according to the feedback signals of the pressure sensor and the displacement sensor. This allows the pressure oil to enter the rodless chamber 120 of the mold-locking cylinder 100 through the second working oil port B. At the same time, the oil in the rod chamber 110 of the mold-locking cylinder 100 flows back to the system oil tank 600 through the one-way lifting valve 300, the first working oil port A, and the return oil port T in sequence. This drives the piston rod to produce a micro-displacement of 0.1 mm to 5 mm.

[0038] This solution integrates a high-frequency response servo valve 200, a one-way lifting valve 300, a two-way lifting valve 400, and a closed-loop sensor controller to construct a high-precision hydraulic control unit.

[0039] When performing the template micro-opening action, the unit utilizes the precise flow regulation capability of the high-frequency response servo valve 200, combined with the real-time feedback from the pressure sensor and displacement sensor, to achieve closed-loop control of the sub-millimeter-level micro-displacement of the piston rod of the mold-locking cylinder 100 within the range of 0.1mm to 5mm.

[0040] Compared to traditional on / off valve systems, it significantly improves the position repeatability accuracy of micro-opening action (up to ±0.1mm) and dynamic response speed (frequency of high-frequency servo valve 200 is not less than 500Hz), effectively meeting the needs of advanced processes such as foam injection molding and thin-wall molding for dynamic adjustment of cavity pressure, and avoiding problems such as uneven density, flash or mold damage in products.

[0041] Meanwhile, this structure simplifies the control logic and hydraulic circuit, providing basic unit support for high-precision and high-reliability mold-locking control.

[0042] Furthermore, this solution also includes a one-way valve 500, which is located at the oil inlet of the system oil tank 600, allowing oil to flow back to the system oil tank 600 in one direction.

[0043] Adding a one-way valve 500 to the oil return path can effectively prevent the oil in the system oil tank 600 from flowing in the opposite direction due to back pressure or external disturbances, ensuring the unidirectionality and stability of the oil return direction during pressure relief or micro-opening.

[0044] This design enhances the system's anti-interference capability under high-frequency switching conditions, avoids pressure fluctuations or position drift caused by oil backflow, and further improves the reliability and repeatability of micro-opening control.

[0045] like Figure 2 As shown, the present invention also provides a servo-controlled mold-locking hydraulic system.

[0046] The injection molding machine includes a moving mold plate and a fixed mold plate. The piston rod of the mold-locking cylinder 100 is connected to the moving mold plate. The servo-controlled mold-locking hydraulic system includes four sets of the above-mentioned hydraulic control units. The four sets of hydraulic control units are arranged in parallel, and the oil inlet P of each high-frequency response servo valve 200 is connected to the system pressure oil source.

[0047] By connecting the four sets of hydraulic control units mentioned above in parallel to the mold clamping system of the injection molding machine, the unified synchronous drive and independent control of multiple cylinders is achieved.

[0048] Each unit shares the same pressure oil source, with a compact structure and simple pipeline. This ensures that the four corners of the large injection molding machine (such as the four-link structure) are evenly stressed during mold closing, mold locking and micro-opening. Furthermore, the controller can be used to make differentiated fine adjustments to each unit to adapt to complex process requirements such as template deformation compensation and two-color co-injection.

[0049] This parallel system not only improves the overall rigidity of the machine, but also significantly reduces the number of hydraulic components required by traditional solutions (by 7 to 12), reducing the volume of the hydraulic station by about 40%, effectively lowering manufacturing costs and maintenance difficulty.

[0050] Furthermore, the high-frequency response servo valve 200 also includes a mold opening control position (the cross position in the figure) and a mold closing control position (the parallel position in the figure);

[0051] When the high-frequency response servo valve 200 is in the mold opening control position, the pressure oil enters the rodless chamber 120 of the mold locking cylinder 100 through the second working oil port B. At the same time, part of the oil in the rod chamber 110 of the mold locking cylinder 100 flows back to the system oil tank 600 through the one-way lifting valve 300, the first working oil port A and the return oil port T in sequence, and another part flows back to the system oil tank 600 through the two-way lifting valve 400, so as to drive the moving template to move away from the fixed template.

[0052] When the high-frequency response servo valve 200 is in the mold closing control position, the pressure oil enters the rod chamber 110 of the mold locking cylinder 100 through the first working oil port A. At the same time, the oil in the rodless chamber 120 of the mold locking cylinder 100 flows back to the system oil tank 600 through the second working oil port B and the return oil port T, so as to drive the moving mold plate to move towards the fixed mold plate.

[0053] By precisely switching between the mold opening control position and the mold closing control position using the high-frequency response servo valve 200, bidirectional and efficient driving of the moving mold plate is achieved: when the mold is open, oil enters the rodless cavity 120 and oil returns to the rod cavity 110, and vice versa when the mold is closed.

[0054] This hydraulic circuit logic fully utilizes the bidirectional controllability of the servo valve, eliminating the need for multiple directional valve combinations in traditional systems and simplifying the hydraulic circuit structure. At the same time, since the entire process is controlled by the same servo valve, the speed, acceleration, and endpoint position of the mold opening and closing action can all be programmably adjusted, supporting smooth switching of multiple speeds within the range of 0 to 500 mm / s, meeting the customized needs of complex molds for motion curves, and improving molding efficiency and product consistency.

[0055] When the high-frequency response servo valve 200 is in the mold closing control position and the pressure in the rod chamber 110 of the mold locking cylinder 100 reaches a preset value, the one-way lifting valve 300 is energized and locked, so that the pressure oil is sealed in the rod chamber 110 of the mold locking cylinder 100, thereby maintaining the high-pressure mold locking state.

[0056] During the mold closing process, when the pressure in the rod cavity 110 reaches the preset clamping force, the one-way lifting valve 300 is energized and locked, sealing the high-pressure oil in the rod cavity 110 to form a reliable mechanical pressure holding state.

[0057] This mechanism can maintain high-pressure clamping without continuous power supply, significantly reducing energy consumption; at the same time, it avoids clamping force attenuation caused by micro-leakage of servo valve, ensuring stable clamping force during long-term pressure holding stages (such as the curing process of foamed materials), effectively preventing melt overflow or product size deviation, and improving yield and mold life.

[0058] After the mold fixed on the fixed template and the moving template is fed, the bidirectional lifting valve 400 is energized, and the oil in the rod chamber 110 of the mold locking cylinder 100 flows to the system oil tank 600 through the bidirectional lifting valve 400, so that the mold locking cylinder 100 is in a depressurized state.

[0059] Before the mold is opened after injection molding is completed, the high-pressure oil in the rod chamber 110 of the mold clamping cylinder 100 is quickly discharged into the oil tank by controlling the bidirectional lifting valve 400 to conduct, thereby achieving efficient and controllable pressure relief operation.

[0060] This pressure relief path is independent of the main servo valve circuit, responds quickly and is not limited by the servo valve flow rate, which can significantly shorten the waiting time before mold opening; at the same time, it avoids mold opening impact or mold plate rebound caused by residual pressure, improving equipment operation safety and cycle efficiency.

[0061] This solution also proposes an injection molding machine, including the aforementioned servo-controlled clamping hydraulic system.

[0062] The workflow of the injection molding machine in this solution is as follows:

[0063] The entire process of mold opening

[0064] When injection molding is complete and the mold needs to be opened, the controller drives the high-frequency servo valve 200 to switch to the mold opening control position. At this time, the system pressure oil enters through the inlet P of the servo valve and exits from the second working port B, entering the rodless chamber 120 of the mold locking cylinder 100; simultaneously, part of the hydraulic oil in the rod chamber 110 flows sequentially through the one-way lifting valve 300, the first working port A of the servo valve, and the return port T back to the system oil tank 600, while the other part flows through the two-way lifting valve 400 and finally returns to the system oil tank 600. Under the action of pressure difference, the piston rod is pushed out, driving the moving platen to move away from the fixed platen, realizing the smooth opening of the mold. The entire process is monitored in real time by a displacement sensor to ensure precise and controllable mold opening stroke.

[0065] The entire process of mold closing

[0066] When mold closing begins, the controller switches the high-frequency response servo valve 200 to the mold closing control position. Pressurized oil enters the high-frequency response servo valve 200 through inlet P and exits through the first working port A, entering the rod chamber 110 of the mold-locking cylinder 100 via the one-way lifting valve 300. Simultaneously, hydraulic oil in the rodless chamber 120 flows back to the system oil tank 600 through the second working port B and return port T. The piston rod retracts under hydraulic pressure, moving the moving platen towards the fixed platen, completing mold closing. This process supports multi-segment speed programming, enabling a flexible mold closing curve of slow-fast-slow, avoiding mold impact, and improving equipment lifespan and molding stability.

[0067] The entire process of mold clamping and high-pressure operation

[0068] After the mold is fully closed, the system enters the high-pressure clamping stage. The high-frequency servo valve 200 continues to maintain the mold closing control position, continuously supplying oil to the rod cavity 110, causing the clamping force to gradually increase. When the pressure sensor detects that the pressure in the rod cavity 110 reaches the preset clamping force threshold, the controller sends a signal to energize and lock the one-way lifting valve 300, cutting off the connection between the rod cavity 110 and the return oil circuit, sealing the high-pressure oil within the rod cavity 110. At this time, even if the servo valve stops supplying oil, the clamping cylinder 100 can still maintain a stable high-pressure state, ensuring that the mold fits tightly during injection molding, preventing melt overflow or flash, and providing a reliable guarantee for high-quality molding.

[0069] The entire process of pressure relief

[0070] Before the injection molding pressure holding is completed and the mold platen micro-movement is prepared, the residual high pressure in the mold clamping cylinder 100 must be released. At this time, the controller energizes the bidirectional lifting valve 400, and the high pressure oil in the rod chamber 110 of the mold clamping cylinder 100 no longer flows back through the high-frequency response servo valve 200, but is directly and quickly discharged into the system oil tank 600 through the bidirectional lifting valve.

[0071] This path is independent of the main servo control loop, and the pressure relief is rapid and controllable. It effectively eliminates the internal pressure of the system before mold opening, avoids mold bouncing or mold opening impact caused by residual pressure, and significantly improves the safety and cycle efficiency of equipment operation.

[0072] Template micro-motion activation process

[0073] After the pressure relief action is completed, in order to adapt to the volume expansion of the foaming material or adjust the cavity pressure, the system performs a template micro-movement opening action.

[0074] Based on feedback from pressure and displacement sensors, the controller drives the high-frequency response servo valve 200 to switch to the micro-open control position: pressurized oil enters the rodless chamber 120 through the second working port B, pushing the piston rod to extend slightly; the oil in the rod chamber 110 flows back to the oil tank sequentially through the one-way lifting valve 300, the first working port A, and the return port T. Because the high-frequency response servo valve 200 has high-frequency response (≥500Hz) and high-resolution flow control capabilities, the piston rod only produces a precise micro-displacement of 0.1mm to 5mm, achieving dynamic fine-tuning of the cavity volume, effectively suppressing defects such as uneven product density and shrinkage marks, while keeping the mold clamping brake in place to ensure process stability.

[0075] Template reset action process

[0076] After the micro-opening action is completed, the mold needs to be fully locked (such as secondary pressure holding), and the system will perform a mold reset action.

[0077] The controller switches the high-frequency response servo valve 200 to the rotary mold control position, and the pressure oil enters the rod chamber 110 again through the first working oil port A, pushing the piston rod to retract and causing the moving mold to re-fit the fixed mold.

[0078] In summary, this solution provides a high-precision, high-response, and highly integrated servo-controlled mold-locking hydraulic system and its hydraulic control unit. Through the collaborative design of the high-frequency response servo valve 200, the one-way lifting valve 300, the two-way lifting valve 400, and the closed-loop sensor controller, it achieves precise, efficient, and flexible control of the injection molding machine throughout the entire process, including mold opening, mold closing, high-pressure mold locking, pressure relief, micro-movement opening of the mold plate, and mold plate reset.

[0079] This system eliminates the complex hydraulic circuit structure of traditional solutions that rely on multiple switching valve combinations, significantly reducing the number of hydraulic components (saving 7–12), reducing the size of the hydraulic station by approximately 40%, and increasing the mean time between failures (MTBF) to 30,000 hours. Utilizing a ≥500Hz high-frequency response servo valve 200 and a pressure / displacement dual closed-loop feedback mechanism, the system achieves position repeatability accuracy of ±0.1mm and sub-millimeter-level template micro-opening control within the range of 0.1mm to 5mm, effectively meeting the stringent requirements of dynamic cavity pressure regulation in high-end processes such as foam injection molding, thin-wall molding, and two-color co-injection.

[0080] Furthermore, the four hydraulic control units are arranged in parallel, ensuring uniform force distribution at the four corners of the large injection molding machine and supporting independent fine-tuning to compensate for template deformation, thus comprehensively improving product dimensional stability and consistency (weight deviation can be controlled within 0.5%). The machine supports seamless switching between three control modes: position, pressure, and speed. The energy consumption per unit product reaches an energy efficiency level of IE3 or higher, and remote monitoring and parameter adjustment can be achieved via industrial Ethernet, reducing maintenance response time to within 2 hours.

[0081] This solution not only solves the technical bottlenecks of traditional mold clamping systems, such as slow response, low precision, and bulky structure, but also sets a new benchmark for hydraulic control of next-generation injection molding equipment in terms of energy saving, reliability, and intelligence.

[0082] It should be noted that in this invention, the use of terms such as "first," "second," and "a" is 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 as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. 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 elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0083] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0084] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A hydraulic control unit for controlling the movement of a mold-locking cylinder, characterized in that, The control unit includes: High-frequency response servo valves, one-way lifting valves, two-way lifting valves, and controllers; The high-frequency response servo valve is provided with an oil inlet P, a first working oil port A, a second working oil port B, and an oil return port T; The oil inlet P is connected to the system pressure oil source, the first working oil port A is connected to the rod chamber of the mold locking cylinder through the one-way lifting valve, the second working oil port B is connected to the rodless chamber of the mold locking cylinder, and the oil return port T is connected to the system oil tank. One end of the bidirectional lifting valve is connected to the rod chamber of the mold-locking cylinder, and the other end is connected to the system oil tank. The bidirectional lifting valve and the one-way lifting valve are connected in parallel in the oil circuit. The controller is electrically connected to the high-frequency response servo valve and signal-connected to the pressure sensor and the displacement sensor respectively; the pressure sensor is used to monitor the oil pressure in the rod chamber or rodless chamber of the mold-locking cylinder in real time, and the displacement sensor is used to monitor the position of the piston rod of the mold-locking cylinder in real time. When the template micro-opening action is performed, the controller drives the high-frequency response servo valve to switch to the micro-opening control position according to the feedback signals of the pressure sensor and the displacement sensor. This allows the pressure oil to enter the rodless chamber of the mold-locking cylinder through the second working oil port B. At the same time, the oil in the rod chamber of the mold-locking cylinder flows back to the system oil tank through the one-way lifting valve, the first working oil port A, and the return oil port T in sequence, thereby driving the piston rod to produce a micro-displacement of 0.1 mm to 5 mm.

2. The hydraulic control unit as described in claim 1, characterized in that, It also includes a one-way valve, which is located at the oil inlet of the system oil tank and allows oil to flow back to the system oil tank in one direction.

3. A servo-controlled clamping hydraulic system, the injection molding machine comprising a moving platen and a fixed platen, characterized in that, The piston rod of the clamping cylinder is connected to the moving template, and the servo-controlled clamping hydraulic system includes: Four sets of hydraulic control units as described in claim 1 or 2, wherein the four sets of hydraulic control units are arranged in parallel, and the oil inlet P of each high-frequency response servo valve is connected to the system pressure oil source.

4. The servo-controlled mold-locking hydraulic system as described in claim 3, characterized in that, The high-frequency response servo valve also includes a mold opening control position and a mold closing control position; When the high-frequency response servo valve is in the mold opening control position, the pressure oil enters the rodless chamber of the mold locking cylinder through the second working oil port B. At the same time, part of the oil in the rod chamber of the mold locking cylinder flows back to the system oil tank through the one-way lifting valve, the first working oil port A and the return oil port T in sequence, and the other part flows back to the system oil tank through the two-way lifting valve, so as to drive the moving template to move away from the fixed template. When the high-frequency response servo valve is in the mold closing control position, the pressure oil enters the rod chamber of the mold locking cylinder through the first working oil port A, while the oil in the rodless chamber of the mold locking cylinder flows back to the system oil tank through the second working oil port B and the return oil port T, thereby driving the moving mold plate to move towards the fixed mold plate.

5. The servo-controlled mold-locking hydraulic system as described in claim 3, characterized in that: When the high-frequency response servo valve is in the mold closing control position and the pressure in the rod chamber of the mold locking cylinder reaches a preset value, the one-way lifting valve is energized and locked, so that the pressure oil is sealed in the rod chamber of the mold locking cylinder, thereby maintaining the high-pressure mold locking state.

6. The servo-controlled mold-locking hydraulic system as described in claim 3, characterized in that: After the mold fixed on the fixed template and the moving template has finished feeding, the bidirectional lifting valve is energized, so that the oil in the rod chamber of the mold locking cylinder flows to the system oil tank through the bidirectional lifting valve, so that the mold locking cylinder is in a depressurized state.

7. An injection molding machine, characterized in that, Includes a servo-controlled mold-locking hydraulic system as described in any one of claims 4 to 6.

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