Injection molding device with auxiliary micro mold opening and glue sealing structure

Abstract

The invention discloses an injection molding device with an auxiliary mold micro-opening and glue sealing structure, and the device realizes accurate micro-opening of a movable mold plate through the synergistic effect of a mold opening and closing assembly and an auxiliary mold opening assembly, so that the micro-opening distance of the movable mold plate can be kept in a controllable range of 0.5 mm-2mm. Therefore, the uniformity of mold cavity exhaust and material flow distribution in the injection molding foaming process is effectively improved; in addition, the structure of the injection screw is optimized, and a spiral dispersing element area and a pin mixing area are sequentially arranged at the head of the injection screw, so that the gas-containing molten material can be efficiently dispersed and homogenized, and the micropore structure and the surface quality of the interior of a product are remarkably improved. Compared with the prior art, the consistency and the size precision of the product can be remarkably improved, the defective rate is reduced, and the mechanical property and the appearance quality of the foamed plastic product are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of injection molding machine device preparation, and particularly relates to an injection molding device with auxiliary micro-opening mold and glue sealing structure. BACKGROUND

[0002] With the increasing demand of modern industry for lightweight, energy saving and high-performance plastic products, the injection foaming process is gradually widely used because it can reduce the weight and material consumption while ensuring the strength of the product. However, the existing injection molding equipment generally has some technical bottlenecks that are difficult to overcome when performing microcellular foaming molding.

[0003] Firstly, in the traditional injection molding machine, the opening and closing control of the mold usually depends on a single opening and closing mold oil cylinder drive, and lacks precise adjustment means for small opening amount, which leads to unstable mold micro-opening, uneven gas discharge, and problems such as uneven distribution of internal pores, collapse or surface defects of the product in the foaming process.

[0004] Secondly, the mixing and dispersion effect of the existing injection screw is limited, and the homogenization ability of the gas-containing melt is insufficient, often causing local aggregation of gas in the melt, thereby affecting the mechanical properties and appearance quality of the product. At the same time, due to the imperfect design of the reverse stop structure at the front end of the screw, the melt is prone to backflow during plasticizing and injection, which not only affects the metering accuracy, but also causes large fluctuations in product weight.

[0005] Thirdly, in the parting surface structure of the mold, the existing technology mostly adopts a simple sealing fit form, lacks a special glue sealing area design, so that the melt is easy to leak from the parting surface during the foaming and expansion stage, not only damaging the appearance edge of the product, but also possibly causing mold wear and gas escape, thereby affecting the stability of the internal cell structure of the product.

[0006] In addition, in terms of back pressure control, the traditional injection molding machine mostly relies on mechanical back pressure or open-loop control method, which is difficult to accurately adjust the pressure at the head of the screw in the plasticizing and metering stage in real time, leading to unstable melt density and material level control, further exacerbating the fluctuations in product quality. SUMMARY

[0007] One object of the present application is to provide an injection molding device with auxiliary micro-opening mold and glue sealing structure, which significantly improves the consistency and dimensional accuracy of the product, reduces the rate of defective products, and improves the mechanical properties and appearance quality of the foamed plastic product.

[0008] To achieve the above object, the first aspect of the present application provides an injection molding device with auxiliary micro-opening mold and glue sealing structure, comprising: The movable die plate and the fixed die plate are oppositely arranged to form an injection molding mold together; The mold opening and closing assembly comprises a first mold opening and closing oil cylinder arranged on the operating side top side of the fixed mold plate and a second mold opening and closing oil cylinder arranged on the non-operating side bottom side of the fixed mold plate, and the piston rod of the mold opening and closing oil cylinder extends along the direction of the movable mold plate and is fixedly connected with the corresponding mounting hole of the movable mold plate. The auxiliary mold opening assembly comprises an auxiliary mold opening oil cylinder assembly and a ejector rod assembly arranged opposite to the auxiliary mold opening oil cylinder assembly, the auxiliary mold opening oil cylinder assembly comprises a first auxiliary mold opening oil cylinder arranged on the operating side bottom side of the movable mold plate and a second auxiliary mold opening oil cylinder arranged on the non-operating side top side of the movable mold plate, and the ejector rod assembly is fixed on the side surface of the bottom of the operating side of the fixed mold plate and the side surface of the top of the non-operating side of the fixed mold plate, respectively, and the auxiliary mold opening oil cylinder assembly and the mold opening and closing assembly are diagonally arranged in the vertical plane. The injection screw is arranged at the center of the barrel. The injection oil cylinder is connected with the injection screw and is used for driving the injection screw to realize reciprocating linear motion and rotation. The active back pressure unit is connected with the control circuit of the injection oil cylinder and is used for applying a reverse force to the injection oil cylinder after the screw plasticizing metering is completed, so as to maintain the head pressure of the injection screw stable and ensure the accuracy of the injection screw material position. The glue sealing structure is arranged on the parting surface of the injection mold formed between the movable mold plate and the fixed mold plate.

[0009] Further, the auxiliary mold opening oil cylinder comprises: The oil cylinder body is fixedly arranged on the fixed frame on one side of the movable mold plate through a screw. The hydraulic ejector rod is fixedly arranged in the oil cylinder body at one end and extends out of the surface of the oil cylinder body at the other end, and the hydraulic ejector rod can reciprocate in the oil cylinder body and is used for directly applying the thrust output by the oil cylinder body to the ejector rod assembly to realize the micro-opening of the movable mold plate. The forward limit switch and the back-off limit switch are arranged at the two ends of the top of the oil cylinder body and are connected with the control circuit, and are used for detecting the stroke limit of the piston rod and feeding back signals. The control circuit is connected with the auxiliary mold opening oil cylinder.

[0010] Further, the control circuit comprises: The hydraulic power source is connected with the system control valve block and the auxiliary mold opening oil cylinder, respectively, and is used for providing hydraulic oil for the auxiliary mold opening oil cylinder. The oil cylinder control valve block is connected with the hydraulic input end of the auxiliary mold opening oil cylinder and the forward limit switch and the back-off limit switch, respectively, and is used for controlling the oil inlet and oil return of the auxiliary mold opening oil cylinder, detecting the extension and retraction position of the piston rod in real time and feeding back to the control system. A system control valve block is connected with the oil cylinder control valve block and a hydraulic power source, and is used for adjusting the hydraulic flow and pressure entering the auxiliary mold opening oil cylinder; Position sensors, which are forward and backward limit switches, are connected with the oil cylinder control valve block, and are used for detecting the extension and retraction positions of the hydraulic top rod in real time and feeding back to the control system; A closed-loop pump flow feedback unit is connected with the hydraulic power source, and is used for monitoring the flow output of the hydraulic power source in real time and transmitting the feedback signal to the control system.

[0011] Further, the detection signal of the position sensor is input to the control system, and the control system controls the stroke and speed of the auxiliary mold opening oil cylinder, so that the micro-opening distance of the movable die plate is kept in a controllable range of 0.5-2 mm.

[0012] Further, the top rod assembly comprises: A fixed device is arranged opposite to the auxiliary mold opening oil cylinder and on the same horizontal line as the auxiliary mold opening oil cylinder, and is fixedly arranged on one side of the fixed die plate; a fixed groove is arranged at the center of the fixed device, and at least one inwardly recessed annular clamping groove is arranged on the inner surface of the fixed groove; A top rod is arranged opposite to the hydraulic top rod, and at least one protruding annular clamping buckle is arranged on the surface of one end of the top rod; the top rod is fixedly connected with the fixed device through the annular clamping buckle and the annular clamping groove; the other end of the top rod extends along the direction of the movable die plate.

[0013] Further, the injection screw comprises: A screw head is provided with a check ring at the front end, which is used for preventing the backflow of molten material during the injection process; the check ring is sequentially provided with a mixing and dispersing section and a metering section towards the direction of the screw tail; A screw tail is connected with the injection oil cylinder of the injection molding machine through a spline, so as to realize the reciprocating linear motion and rotation of the injection screw under the driving of the injection oil cylinder.

[0014] Further, the metering section mainly comprises screw ribs and screw grooves arranged along the axial direction of the injection screw.

[0015] Further, the screw ribs are helically distributed and continuously extended along the axial direction of the injection screw, and at least one screw groove is formed between the screw ribs and the injection screw body.

[0016] Further, the mixing and dispersing section of the screw head comprises, from front to back, starting from the metering section: The spiral dispersing element area is used to break up and disperse gas components during material flow and to convey initially dispersed molten material. The pin mixing zone, located after the spiral dispersing element zone, is used to further stir and homogenize the gas-containing molten material, thereby forming a homogeneous melt.

[0017] Furthermore, the surface of the spiral dispersing element region is provided with at least one shallow groove along the screw axis to maintain the spiral guiding effect when the material moves forward, avoid local stagnation, and form a stable laminar flow distribution.

[0018] Furthermore, the depth of the shallow trench is 0.2-0.4 mm.

[0019] Furthermore, a smooth transition zone is provided between the metering section and the spiral dispersing element area.

[0020] Furthermore, the length of the smooth transition zone is 0.5-1.0 times the diameter of the cross-section of the spiral dispersion element region.

[0021] Furthermore, the pin mixing zone includes at least one guide ring arranged along the screw axis, and at least three radially protruding pins are provided on the guide ring, the pins being arranged obliquely relative to the screw axis on the guide ring.

[0022] Furthermore, the screw head is connected to the locking nozzle of the injection molding machine to allow the melt to enter the injection mold cavity during the injection stage and to prevent melt backflow during the plasticizing stage.

[0023] Furthermore, the sealing structure is disposed around the parting surface of the injection mold, including: A thin-walled region, the thickness of which is 0.8-1.2 mm, is used to allow the molten plastic to cool and solidify rapidly in this region after injection. A cooling barrier zone, which is formed by extending the thin-walled zone outward from the parting surface, has a width of at least 1.5-2 times the mold foam thickness.

[0024] Furthermore, it also includes: A high-pressure hydraulic cylinder assembly, comprising four high-pressure hydraulic cylinders arranged in a rectangular symmetrical manner at the four corners of the moving template away from the fixed template; A lock-up nozzle is located between the barrel head and the injection mold gate. The lock-up nozzle is fixedly connected to the barrel via a flange. It is used to open under hydraulic drive during the injection stage to allow the melt to be injected into the mold cavity, and to close during the plasticizing and back pressure stages to ensure metering and prevent melt backflow.

[0025] The embodiments of this application have the following technical effects: (1) This application achieves precise control of the moving mold platen within a micro-opening range of 0.5mm-2mm through the synergistic action of the auxiliary mold opening cylinder and the mold opening and closing cylinder. This design significantly improves the mold opening accuracy and avoids problems such as uneven melt flow, wall thickness deviation, and ineffective gas discharge caused by uneven force during the mold micro-opening process or the need for greater mold opening force due to mold structure in traditional injection molding equipment. By precisely controlling the micro-opening distance, this application can effectively prevent surface defects of injection molded parts and improve the quality and appearance consistency of the products, especially showing unique advantages in the production of high-precision foamed and thin-walled injection molded products.

[0026] (2) The injection screw design used in this application enables sufficient gas dispersion and melt mixing during the injection process. Through the spiral barrier element and screw groove in the spiral dispersion element zone, the gas components are effectively dispersed, preventing gas aggregation and melt stagnation, resulting in a more uniform flow of molten material. Furthermore, the pin mixing zone further optimizes the uniformity of the melt, improving the dispersibility and mechanical properties of the plastic. Compared with traditional injection molding equipment, this invention significantly reduces the generation of bubbles and material defects while ensuring melt uniformity, making it particularly suitable for precision injection molded products with extremely high melt quality requirements.

[0027] (3) This application incorporates a sealing structure at the parting surface, enabling the molten plastic to cool and solidify rapidly, thereby improving the mold's cooling efficiency and production cycle. Simultaneously, the sealing structure effectively simplifies the mold structure, reduces mold complexity, prevents external cooling sources from affecting the interior of the injection molded part, ensures stable melt temperature, and avoids problems such as uneven cooling, overflow, or deformation on the mold surface due to excessively rapid cooling. This sealing structure effectively improves mold sealing, reduces defects caused by gas overflow or uneven cooling, and increases product yield and production efficiency.

[0028] (4) The active back pressure unit designed in this invention can monitor and adjust the back pressure of the injection cylinder in real time to ensure that the screw maintains a stable pressure output during the plasticizing process. Especially in the screw plasticizing and metering stages, the back pressure control system of this invention not only improves the stability of the melt and the accuracy of the material level, but also effectively reduces common defects such as uneven filling, shrinkage marks and porosity in the traditional injection molding process, thereby improving the quality and repeatability of the molded parts. Attached Figure Description

[0029] The accompanying drawings, as part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application, but do not constitute an undue limitation of this application. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of an overall device for an injection molding apparatus with an auxiliary micro-mold opening and sealing structure, as shown in some embodiments of this application. Figure 2 This is a structural diagram of an auxiliary mold-opening cylinder in an injection molding device with an auxiliary micro-mold-opening and sealing structure, as described in some embodiments of this application. Figure 3 This is a schematic diagram showing the setting position of the mold opening and closing cylinder on the fixed template in an injection molding device with an auxiliary micro-mold opening and sealing structure in some embodiments of this application; Figure 4 This is a schematic diagram showing the setting position of the auxiliary mold opening cylinder on the moving template in an injection molding device with an auxiliary micro-mold opening and sealing structure in some embodiments of this application; Figure 5 This is a schematic diagram of the sealing structure in an injection molding device with an auxiliary micro-mold opening and sealing structure in some embodiments of this application; Figure 6 This is a schematic diagram of the structure of the injection screw head in an injection molding device with an auxiliary micro-mold opening and sealing structure in some embodiments of this application; Figure 7 This is a schematic diagram of the control circuit of the auxiliary mold opening cylinder in an injection molding device with an auxiliary micro-mold opening and sealing structure in some embodiments of this application.

[0030] The components include: 1. Moving mold plate; 2. Auxiliary mold opening cylinder; 3. Mold opening and closing cylinder; 4. High-pressure cylinder; 5. Ejector rod; 6. Fixed mold plate; 7. Fixer; 8. Locking nozzle; 9. Material barrel; 10. Inlet; 11. Injection cylinder; 12-1 Second mold opening and closing cylinder; 12-2 First mold opening and closing cylinder; 13. Starting position of spiral dispersing element area; 14. Metering section; 14-1. Spiral ridge; 14-2. Spiral groove; 15. Pin mixing area; 15-1. Guide ring; 15-2. Pin; 16. Spiral dispersing element area; 16-1. Shallow groove; 17. Smooth transition area. 2-1. Hydraulic push rod; 2-2. Forward limit switch; 2-3. Reverse limit switch; 2-4. Cylinder body; 2-5. Hydraulic power source; 2-6. System control valve block; 2-7. Cylinder control valve block; 2-8. Closed-loop pump flow feedback unit; 2-9. Position sensor; 201 First auxiliary mold opening cylinder; 202 Second auxiliary mold opening cylinder. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0032] In the description of this application, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Those skilled in the art should understand that the embodiments described below are merely a part of the embodiments of this application, and not all of the embodiments of this application. These partial embodiments are intended to explain the technical principles of this application and are not intended to limit the scope of protection of this application. Based on the embodiments provided in this application, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of this application.

[0035] Please see Figure 1 The injection molding device with auxiliary micro-mold opening and sealing structure provided in this application includes: 1. a moving mold plate; 2. an auxiliary mold opening cylinder; 3. a mold opening and closing cylinder; 4. a high-pressure cylinder; 5. an ejector rod; 6. a fixed mold plate; 7. a retainer; 8. a locking nozzle; 9. a barrel; 10. a feed port; and 11. an injection cylinder.

[0036] The specific working process of this injection molding device is as follows: (1) The working process begins with the fixed template 6 and the moving template 1 working together under the cooperation of the first mold opening and closing cylinder 12-2 and the second mold opening and closing cylinder 12-1. The moving template 1 moves towards the fixed template 6 to achieve mold closing. At this time, the molds mounted on the fixed template 6 and the moving template 1 are closed to form an injection mold.

[0037] (2) The material mixed with foaming agent is then conveyed into the barrel 9 through the feed port 10 on the injection molding device. The barrel plays an important role in the entire device in terms of bearing, heating and conveying materials, and an injection screw is installed through the center of the barrel. As the injection screw rotates and retracts, the material entering the barrel is gradually pushed forward. At the same time, under the dual action of the electric heating coil outside the barrel and the rotation and shearing of the injection screw, the material gradually melts and is continuously conveyed to the metering section 14 of the injection screw. Inside the barrel 9, the gaps between the materials are compressed, and the foaming agent is evenly dispersed under the shearing action of the injection screw. The material transitions from a solid particle state to a viscous flowing melt. A check ring is provided near the head of the injection screw. During the material conveying and plasticizing process, the check ring remains open to ensure that the plasticized and metered melt is conveyed to the front section of the injection screw and metered, thereby ensuring that the material is fully compressed and evenly heated in the forward direction.

[0038] In existing technologies, most common injection screw structures follow the traditional three-section configuration: feeding section, compression section, and metering section. While this can meet the needs of general melt conveying, it has significant shortcomings when handling materials mixed with gaseous components or foaming agents. First, the distribution and mixing effect of materials in traditional screws is limited during plasticizing and conveying, especially between the compression and metering sections. Due to the simple screw channel structure, the material is prone to local temperature unevenness and pressure fluctuations, resulting in insufficient gas dispersion in the melt, producing large bubbles or gas accumulation areas. This not only affects the appearance quality of the product but also seriously weakens its mechanical properties.

[0039] Therefore, to solve the above problems, this embodiment provides an injection screw, which includes a screw head and a screw tail. For example... Figure 6 As shown, where Figure 6 The screw head structure of the injection screw is shown. This embodiment significantly improves the homogenization and mixing effect of materials before injection through a specially designed mixing and dispersing section at the screw head.

[0040] like Figure 6 As shown, the injection screw head includes a mixing and dispersing section 14 and a metering section 14. The mixing and dispersing section is composed of a spiral dispersing element area 16 and a pin mixing area 15 in sequence. Figure 6 The diagram shows that the starting position 13 of the spiral dispersion zone is located behind the metering section 14. The metering section 14 mainly consists of a spiral barrier element and a screw groove 14-2 arranged along the axial direction of the injection screw. Figure 6As can be seen, in the metering section 14 region, this embodiment achieves a smaller spacing between adjacent threads compared to existing technologies through the arrangement of the screw ridges. A smaller spacing means an increase in the number of screw channels per unit length, effectively providing more opportunities for the gradually melting material to undergo force and compressive shearing melting. When the injection screw rotates and propels the material forward, the material's movement path within the narrow screw channels is more constrained, resulting in stronger pushing and shearing effects. This not only accelerates the densification process of the particles but also enhances the heat transfer efficiency between the solid and molten phases, leading to more complete and uniform plasticization. Simultaneously, the smaller spacing improves the stability of the material during axial transport, preventing large particles or locally unmelted material from flowing back or forming dead zones, thus contributing to the continuity and homogeneity of the entire melt. For injection molding, the stability and homogeneity of the melt directly determine the dimensional stability, surface quality, and internal mechanical properties of the product. Therefore, this invention reduces the defects caused by melt inhomogeneity at the source by decreasing the screw spacing.

[0041] In contrast, existing technologies typically have larger thread pitch in the metering section, usually with only one threaded edge. This embodiment uses two threaded edges, resulting in a smaller spacing between adjacent threads in the metering section. While existing technologies may reduce processing and manufacturing difficulties in terms of design, the resulting process problems cannot be ignored. First, the larger spacing increases the cross-sectional area of ​​the screw channels, reducing the constraint on the material and leading to flow stratification or even partial backflow during transport. When the melt carries unmelted solid particles, these large-spacing screw channels often cannot form effective compression and shear, allowing the solid particles to enter the subsequent mixing and dispersion zone. This significantly increases the burden on the downstream mixing and dispersion zone, leading to the accumulation of inhomogeneities in the melt and potentially resulting in impurities or streaks in the finished product. Second, the larger spacing means fewer threaded edges per unit length, resulting in a relatively insufficient contact area between the material and the screw, weakening heat transfer and frictional heating. This makes it difficult to quickly establish a temperature field in the melt, easily leading to insufficient material temperature or localized overheating, resulting in uneven shrinkage during product molding, obvious weld lines, or even decomposition and coking. More importantly, with larger spacing, the material is less stable during transport and is prone to pulsating forward movement due to back pressure fluctuations or changes in raw material characteristics. This leads to reduced metering accuracy and fluctuations in injection volume, directly affecting the repeatability and consistency of molding.

[0042] (2-1) The material first enters the metering section area.

[0043] Specifically, such as Figure 6As shown, the metering section 14 mainly consists of screw ridges 14-1 and screw grooves 14-2 arranged along the screw axis. The screw ridges 14-1 are spirally distributed and continuously extend along the injection screw axis, and at least one screw groove 14-2 is formed between the screw ridges 14-1 and the injection screw body as the screw ridges 14-1 continuously extend along the injection screw axis. As the screw rotates, the material is forced forward along the screw grooves and is gradually compressed under the pushing of the screw ridges. Because the screw pitch of the metering section is smaller than that of the traditional design and the cross-section of the screw grooves is reduced, the looseness of the material in the channel is reduced and the packing density between solid particles is increased. This not only enhances the friction and shearing between the materials, but also accelerates the heat conduction speed between the material and the inner wall of the barrel and the screw surface, thereby effectively improving the melting efficiency.

[0044] As the material progresses along the metering section, its internal structure gradually transforms from primarily solid particles to a mixed state where solid and melt coexist. The screw ribs here not only act as a propulsion mechanism but also as shear units. Once the molten layer forms on the particle surface, the relative motion within the screw channels generates a significant shear flow field, allowing the melt to penetrate and encapsulate between the solid particles, promoting further homogenization of the plasticizer. Therefore, the metering section becomes the initial and crucial melt preparation area in the entire injection screw, ensuring that the material entering the subsequent mixing and dispersing section already possesses a high melt ratio and initial homogeneity. Without this compact conveying and compaction, the material may enter the downstream section in an excessively solid or semi-molten state, leading to decreased mixing efficiency or even molding defects.

[0045] (2-2) The material then enters the smooth transition zone 17.

[0046] In existing designs, if the melt directly enters the mixing and dispersion zone without a transition zone, it will suddenly encounter complex shearing and disturbances, easily leading to local stagnation, excessive heating, or stratification, resulting in defects such as degradation, bubble entrainment, or uneven mixing. Therefore, to avoid the problems caused by the material directly entering the mixing zone, this embodiment also sets a smooth transition zone 17 between the starting position 13 of the spiral dispersion element zone and the spiral dispersion element zone 16, with the length of the smooth transition zone 17 set to 0.5-1.0 times the diameter of the spiral dispersion element zone 16. Thus, through the buffer design of the specific length of the smooth transition zone, the spiral guide angle and flow pattern gradually change in space. During this process, the melt gradually transitions from unidirectional axial conveying to multidirectional disturbed dispersion flow, avoiding the impact caused by sudden changes in flow velocity and providing sufficient preparation for subsequent dispersion and mixing. Simultaneously, this zone also serves as a buffer for the temperature and pressure fields, allowing the melt to redistribute internal stress before entering the dispersion zone, thereby ensuring more uniform and efficient subsequent dispersion.

[0047] (2-3) The material then enters the spiral dispersion element area 16.

[0048] When the material enters the spiral dispersing element zone 16, the shallow grooves 16-1 on its surface serve to guide and stabilize the flow. When processing gas-containing or foamed materials, the design of the shallow grooves 16-1 helps to achieve a more uniform distribution of gas components in the melt. By enhancing the guiding effect of the melt, it ensures a stable distribution of gas during the flow process, avoiding bubble aggregation or uneven dispersion, thereby improving the surface quality and mechanical properties of the product. These shallow grooves 16-1, while maintaining the spiral advance of the material, also reduce the formation of local stagnation zones, preventing thermal degradation or carbonization of the melt due to retention. Simultaneously, the depth of the shallow grooves 16-1 is set to 0.2-0.4 mm. This design aims to ensure that the melt maintains a stable laminar flow state, avoiding melt retention on the screw surface, thereby reducing the risk of thermal degradation or uneven plasticization.

[0049] (2-4) Finally, the material enters the pin mixing zone 15.

[0050] By employing at least three inclined pins 15-2 arranged on the guide ring 15-1 in the pin mixing zone 15, forced shearing and disturbance are applied to the melt, achieving final homogenization of the material before injection, thereby obtaining a melt with uniform distribution and stable structure. The pins 15-2 are evenly distributed on the guide ring 15-1, with adjacent pins 15-2 forming equal angles with the center of the guide ring 15-1. This is done to ensure that the material is uniformly subjected to shearing and disturbance as it passes through the pin mixing zone 15. Specifically, the uniform distribution of pins 15-2 on the guide ring 15-1 ensures that the melt experiences the same degree of shearing and diversion as it flows through this area. If the pins are unevenly distributed, some areas of the melt will experience excessive disturbance, while others may experience insufficient shear, resulting in uneven melt flow throughout the screw head and ultimately affecting product quality and performance.

[0051] (3) After the material is processed by the screw head of the injection screw, it forms a homogeneous melt. This homogeneous melt gradually gathers at the front end of the injection screw and is compressed, stored and metered by back pressure until the preset injection screw metering stroke is reached.

[0052] Simultaneously, an active back pressure unit connected to the hydraulic circuit of the injection cylinder applies a reverse force to the tail of the injection screw after plasticizing and metering, preventing the injection screw from moving uncontrollably backward due to excessive pressure at the melt tip. By applying a stable reverse thrust, this unit ensures that the pressure at the screw tip remains within a stable range, making the screw position precise and ensuring that the melt volume measured each time is accurate.

[0053] In existing technologies, active back pressure units in injection screws are typically used to ensure stable screw head pressure, thereby maintaining uniform melt flow and precise, repeatable material level control during plasticizing and metering. Traditional screw back pressure units usually apply reverse force through mechanical devices or simple hydraulic control, stopping operation when the screw reaches the set material level during the plasticizing stroke. However, these traditional designs have several drawbacks, particularly in accurately controlling melt flow and maintaining the injection screw material level, often resulting in instability. For example, traditional back pressure units cannot operate after plasticizing to ensure a stable final plasticizing position of the screw, failing to guarantee consistency and repeatability of the screw's starting position for each injection. This non-repeatability of the material level leads to melt density deviations, thus affecting the quality of the molded product and production efficiency. Furthermore, traditional back pressure units only operate during plasticizing, especially when handling high-viscosity or foamed materials, and cannot effectively cope with changes in screw displacement driven by the high-pressure melt after plasticizing.

[0054] Therefore, to solve the above problems, this embodiment provides an active back pressure unit. Connected to the control circuit of the injection cylinder, after the injection screw has completed plasticizing and metering, the injection molding machine's control system controls the injection cylinder to apply a reverse force to the tail of the injection screw via the injection cylinder's control circuit. This reverse force acts directly on the tail of the injection screw, thereby preventing the injection screw from retracting or pushing it back to a designated position, ensuring a stable material level throughout the injection process and preventing melt backflow or uneven flow.

[0055] Specifically, after plasticizing, when the homogeneous melt gathers at the screw head, the active back pressure unit starts to work. The active back pressure unit has an independent hydraulic power source, and the hydraulic power source is directly connected to the control circuit of the injection cylinder 11. This connection allows the injection molding machine's control system to reuse the control circuit of the injection cylinder, thus ensuring that the injection screw maintains a stable material level throughout the injection process without the need to introduce an additional control circuit of the active back pressure unit.

[0056] When the active back pressure unit starts working, the injection molding machine's control system sends a command to the control circuit of the injection cylinder. Subsequently, the hydraulic power source of the active back pressure unit inputs stable high-pressure hydraulic oil into the injection cylinder, and the system control valve block of the injection cylinder adjusts the hydraulic flow and pressure according to the command issued by the control system, thereby ensuring that the actual position of the screw is consistent with the plasticizing endpoint setting position, and providing the required pressure for the melt at the injection screw head. Specifically, as plasticizing metering is gradually completed, molten material accumulates at the front end of the screw head. The screw gradually retracts until it reaches the set position of the plasticizing endpoint. At this time, the active back pressure unit plays a role, adjusting the back pressure through the feedback adjustment function of the system control valve block to ensure that the screw endpoint position is always maintained at the set value, that is, the screw position is always kept constant. In this process, the feedback adjustment function of the system control valve block is particularly critical: when there is a difference between the actual value of the screw position signal and the set position of the plasticizing endpoint, the signal will be fed back to the system control valve block in real time. The system control valve block quickly adjusts the flow rate and output pressure of the hydraulic power source of the active back pressure unit according to the preset parameters, thereby keeping the screw position consistent with the plasticizing endpoint position.

[0057] (4) When entering the injection stage, the injection cylinder 11 drives the injection screw from a stationary state to move forward rapidly in the axial direction. The check ring is closed at this time, allowing the homogeneous melt to enter the locking nozzle 8 under high pressure. The locking nozzle 8 is hydraulically opened during the injection stage, forming a channel that allows the homogeneous melt to smoothly enter the injection mold gate and fill the mold cavity. Before this, the mold mounted on the moving platen and the fixed platen has been completely closed under the action of the mold opening and closing assembly, and the mold cavity of the injection mold is tightly sealed.

[0058] Specifically, the mold opening and closing of the injection mold are achieved by a mold opening and closing assembly mounted on the fixed mold platen 6. The mold opening and closing assembly includes two mold opening and closing cylinders located on both sides of the fixed mold platen 6. Their piston rods, through axial force, drive the moving mold platen relative to the fixed mold platen. The clamping force is provided by a high-pressure cylinder group mounted on the moving mold platen 1. This high-pressure cylinder group includes four high-pressure cylinders, which are symmetrically arranged in a rectangle at the four corners of the moving mold platen on the side furthest from the fixed mold platen. These four high-pressure cylinders apply a uniform clamping force to the four corners of the moving mold platen, keeping the mold stable during high-pressure filling.

[0059] like Figure 3As shown, the mold opening and closing assembly consists of a first mold opening and closing cylinder 12-2 located on the top side of the operating side of the fixed mold plate 6, and a second mold opening and closing cylinder 12-1 located on the bottom side of the non-operating side of the fixed mold plate 6. The piston rods of both the first and second mold opening and closing cylinders 12-2 and 12-1 extend along the direction of the fixed mold plate 6 and are fixedly connected to mounting holes located on the top operating side and the bottom non-operating side of the fixed mold plate, respectively. The first and second mold opening and closing cylinders 12-2 and 12-1 are fixed at different positions on the fixed mold plate, and their piston rods extend along the direction of the moving mold plate and are reliably mechanically fixedly connected to corresponding mounting holes on the moving mold plate. Through this arrangement, the two mold opening and closing cylinders can generate thrust or pull under hydraulic power, thereby pushing the moving mold plate 1 away from or towards the fixed mold plate 6, thus realizing the mold opening and closing of the injection molding machine.

[0060] Specifically, during the mold closing process of the injection molding machine, the collaborative working process of the mold opening and closing components is as follows: During the mold closing stage, the injection molding machine's control system sends commands to the control circuits of the first and second mold opening / closing cylinders 12-2 and 12-1. The system control valve block in these control circuits first inputs high-pressure hydraulic oil into the rodless chambers of the two cylinders 12-1 and 12-2 according to the control program. This forces the pistons of the two cylinders to gradually retract inwards along the axial direction of the cylinder body, thereby driving the piston rod connected to the piston to retract towards the fixed mold plate 6. This retraction is not a simple mechanical displacement, but rather a pulling effect achieved through the rigid connection between the piston rod and the moving mold plate 1. As the piston moves backward within the cylinder cavity, it pulls the piston rod, which is coaxially fixed to it, towards the fixed mold plate 6. The free end of this piston rod is firmly connected to the mounting hole of the moving mold plate 1. Therefore, driven by the first and second mold opening / closing cylinders 12-2 and 12-1, the moving mold plate 1 is gradually pulled forward, bringing it closer to the fixed mold plate 6 until the mold contact surfaces of the two are completely closed, forming the injection mold. During this process, the control loop needs to continuously monitor pressure, stroke and speed to ensure that the mold closing action is both fast and smooth, so as not to cause violent collision between the moving platen 1 and the fixed platen 6 due to excessive speed, nor to affect the injection rhythm due to excessive speed.

[0061] (5) After the homogeneous melt is injected into the mold, it quickly fills all areas of the mold. At this time, due to the design around the parting surface of the mold, it is as follows: Figure 5 The sealing structure shown, wherein Figure 5 The left side shows the injection mold in a closed state, meaning the moving template has not yet achieved micro-opening, while the right side shows the injection mold in a micro-opening state, where the material forms a sealed boundary after being treated by the sealing structure, preventing other material from overflowing from the edge.

[0062] In existing technology, when the mold is closed and the injection stage begins, the homogeneous melt is injected into the mold cavity at extremely high speed and pressure. At this time, the mold parting surface, as the contact interface between the two mold plates, has a certain clamping force in its mechanical structure. However, when the holding pressure ends and the mold opening and foaming stage begins, the moving mold plate makes a slight opening movement. At this time, the clamping force is removed. Without a special sealing structure, the undried melt will overflow from the parting surface, resulting in product defects.

[0063] Therefore, to avoid the above problems, this embodiment provides a sealing structure for the parting surface. Through the dual design of material processing and mold structure, the parting surface, which may have been a source of defects, is transformed into an active sealing barrier. Utilizing the rapid solidification characteristics of the molten material in the thin-walled region, a "sealing line" is constructed that spontaneously forms during the filling process. This sealing line takes effect immediately upon completion of the injection holding stage, not only improving the sealing effect but also significantly reducing the dependence on mechanical clamping force, thus optimizing the equipment in terms of energy consumption, mold structure complexity, strength requirements, and cost. The sealing structure also plays an irreplaceable role in the subsequent auxiliary micro-mold opening process. When the auxiliary mold opening cylinder actuates to create a small gap of 0.5mm to 2mm between the moving and fixed mold plates, the inside of the mold cavity is still at a high temperature and a certain residual pressure. Without an effective sealing structure, molten material or gas may overflow along the micro-opening, resulting in uneven foaming or surface defects at the product edges. The curing ring and cooling barrier formed by the sealing structure can effectively maintain the seal of the mold cavity boundary, ensuring that the micro-molding only releases gas or produces a controllable foaming effect within a preset range, without damaging the edge quality of the product.

[0064] Specifically, the sealing structure is disposed around the parting surface of the injection mold, and is arranged in a ring around the parting surface. The sealing structure includes: The thin-walled zone, with a thickness of 0.8-1.2 mm, is used to allow the molten plastic to cool and solidify rapidly within this area after injection. The sealing structure is designed to quickly form a localized, high-strength sealing band around the mold parting surface after injection and before micro-foaming, ensuring that melt leakage (i.e., flash) does not occur inside the mold cavity when the foaming pressure increases, while simultaneously ensuring that the main body of the mold cavity can smoothly micro-open to achieve foaming. For this application, the thin-walled zone is its first and core active sealing mechanism. This area is designed to be extremely thin, with a thickness of 0.8-1.2 mm. When the high-temperature homogeneous melt enters the mold cavity through the injection screw and the locking nozzle and fills the periphery of the parting surface, the thin-walled zone rapidly conducts heat due to its extremely small wall thickness, causing the molten material to cool and solidify rapidly in this narrow area, forming a strong solidified ring. The solidification ring forms in an extremely short time, almost simultaneously with the filling process of the main body of the mold cavity. Therefore, it can seal and lock the edge of the mold cavity at a very early stage, essentially creating a "sealing line" for the mold. This sealing line prevents the molten material, which is still under high temperature and pressure, from leaking out of the parting surface, thus effectively preventing the appearance of flash or burrs. At the same time, this thin-walled area can also use the strength of the solidified material itself to resist the impact and expansion of the uncured molten plastic inside on the parting surface under high pressure, ensuring the stability and tightness of the mold cavity boundary.

[0065] However, relying solely on rapid cooling of the thin-walled area to form a sealing ring is insufficient for a sealing structure. If adjacent mold areas also cool at the same high rate, the resulting rigid sealing ring will transfer its stress, potentially constraining or even preventing the smooth execution of micro-opening actions, or causing the brittle area to crack during mold micro-movements. This is the fundamental reason for the existence of the "cooling barrier zone."

[0066] Specifically, as shown in the figure, the cooling barrier zone extends outward from the thin-walled region, with a width at least 1.5-2 times the mold-opening foam thickness. This mold-opening foam thickness refers to the mold-opening distance of the moving mold plate after micro-mold-opening processing, thus providing additional space for foaming. Figure 5 The image shows a 2mm cooling barrier zone. This cooling barrier zone is positioned adjacent to the thin-walled zone and serves to extend and reinforce the sealing structure. Its width is at least 1.5 to 2 times the thickness of the foam, meaning there is a relatively wide area outside the thin-walled zone. Its main function is to form an additional barrier through spatial expansion and further control of the cooling rate. During operation, the relatively large lateral dimension of the cooling barrier zone allows the molten material to rapidly cool in this extended area, even after passing through the initial cooling ring of the thin-walled zone, until it completely loses its fluidity. This design effectively prevents plastic leakage caused by minor mold opening and closing errors or high-pressure impacts.

[0067] (6) After the mold filling is completed, the pressure holding stage is entered. At this time, the injection cylinder 11 still maintains a certain pressure to compensate for the volume loss of the melt during the cooling and shrinkage process, and to ensure that the surface of the product is full and without shrinkage marks.

[0068] (7) When the product is basically formed, the device enters the auxiliary micro-mold opening stage.

[0069] In traditional injection mold opening and closing control, the moving mold platen is typically closed and opened by mold opening and closing assemblies arranged on both sides of the fixed mold platen. This structure can meet basic process requirements during large-stroke mold closing and opening actions. However, when the mold needs to open and close slightly after injection to release gas or adjust product foaming, relying solely on the mold opening and closing assemblies to drive the moving mold platen to open slightly reveals obvious defects. The mold opening and closing cylinder itself has a long stroke and large output, mainly for locking and separating the overall mold platen. Its motion inertia is large, making it difficult to achieve precise control of small distances, especially when the micro-opening stroke is only within the range of 0.5mm to 2mm. The cylinder's execution often manifests as abrupt action or uneven return. In addition, because the mold opening and closing assemblies are located at symmetrical points on the fixed mold platen, the force can be relatively balanced when driving the moving mold platen to open with a large stroke. However, in the micro-opening stage, due to the complex factors such as residual pressure inside the mold cavity, differences in product force, and mold center of gravity shift, the moving mold platen often cannot maintain uniform force. Therefore, relying solely on the mold opening and closing assembly for driving can easily cause one end of the moving mold plate to open first while the other end lags behind, resulting in uneven stress on the mold parting surface and unstable micro-opening gaps, which in turn affects the gas release path and the edge quality of the product. This uneven stress phenomenon is particularly evident in high-precision products and foaming process control, often leading to edge warping, uneven pore distribution, or flash defects, and in severe cases, it can even damage the precision mating surfaces of the mold.

[0070] Therefore, to solve the above problems, this embodiment proposes to set an auxiliary mold opening component on the moving template, which works in conjunction with the mold opening and closing component. The auxiliary mold opening component adopts a diagonally arranged structure: auxiliary mold opening cylinders are set at the bottom of the operating side and the top of the non-operating side of the moving template, and corresponding push rod components are set on the corresponding sides of the fixed template. The two cooperate with each other to form an interlaced force layout with the mold opening and closing cylinders in the vertical plane. The fundamental purpose of this design is to increase the independent source of cylinder driving force and achieve a balanced force distribution through diagonal arrangement, so that the moving template can maintain a balanced force state under multi-point drive during the micro-opening stage. Unlike relying solely on the mold opening and closing cylinders, the auxiliary mold opening cylinders have a short stroke, high control precision, and are specifically designed for micro-opening actions. Under the adjustment of the control loop, they can output stable and controllable small displacements, which helps to keep the gap generated by the moving template stably within the range of 0.5mm to 2mm. This design effectively avoids the problem of skewing or jamming caused by uneven force on the moving template, making the micro-opening action not only smooth and reliable, but also highly accurate and repeatable.

[0071] Specifically, such as Figure 4 As shown, the moving template 1 is provided with an auxiliary mold opening assembly. The auxiliary mold opening assembly includes an auxiliary mold opening cylinder assembly and a push rod assembly disposed opposite to the auxiliary mold opening cylinder assembly. The auxiliary mold opening cylinder assembly includes a first auxiliary mold opening cylinder 201 disposed on the bottom side of the operating side of the moving template 1, and a second auxiliary mold opening cylinder 202 disposed on the top side of the non-operating side of the moving template 1.

[0072] Specifically, such as Figure 2 As shown, Figure 2 The diagram shows the specific structure of the first auxiliary mold opening cylinder 201. Since the specific structure of the first auxiliary mold opening cylinder is the same as that of the second auxiliary mold opening cylinder, the only difference is the setting position of the two cylinders. Therefore, the description of the structure of the auxiliary mold opening cylinder in this embodiment takes the first auxiliary mold opening cylinder 201 as an example.

[0073] like Figure 2 As shown, the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202 both include a cylinder body 2-4, a hydraulic push rod 2-1, a forward limit switch 2-2, a backward limit switch 2-3, and a control circuit.

[0074] Specifically, in the structure of the first auxiliary mold opening cylinder 201: The cylinder body 2-4 is fixedly mounted on a bracket on one side of the moving template using screws. This mechanical mounting structure of the cylinder body 2-4 embodies the design's stability and efficient force transmission path. The screw-fixed mounting method not only ensures the rigidity of the connection, preventing loosening under frequent impact loads, but more importantly, it integrates the auxiliary mold-opening cylinder with the moving template into a single unit. This ensures that the output thrust can act directly and without loss on the subsequent ejector assembly, ultimately translating into precise displacement of the moving template.

[0075] A hydraulic push rod 2-1, with one end fixed inside the cylinder body 2-4 and the other end extending out of the surface of the cylinder body 2-4, can reciprocate within the cylinder body 2-4. It is used to directly apply the thrust output from the cylinder body 2-4 to the push rod assembly to achieve micro-opening of the moving template. In this application, the hydraulic push rod 2-1, as the actuating end, with one end placed inside the cylinder body 2-4 and the other end extending out, can reciprocate within the cylinder body 2-4. It is the core component in the entire mechanism that converts hydraulic energy into mechanical kinetic energy. Its design directly affects the smoothness of the thrust output, the response speed, and the service life.

[0076] Forward limit switch 2-2 and retraction limit switch 2-3 are respectively located at both ends of the top of the cylinder body 2-4, used to detect the stroke limit of the hydraulic push rod 2-1 and provide feedback signals. Their function is to detect whether the hydraulic push rod 2-1 has reached its physical stroke limit. This is a safety protection mechanism to prevent the hydraulic push rod 2-1 from overextending or retracting, causing mechanical damage. Simultaneously, the signals they emit can also be used for initial position calibration of the system.

[0077] Control loop, such as Figure 7 As shown, where Figure 7 The diagram shows a control circuit connected to the first auxiliary mold opening cylinder 201. However, since the control circuits of the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202 are the same, the only difference is their respective positions. Therefore, this embodiment will take the control circuit connected to the first auxiliary mold opening cylinder 201 as an example for further explanation.

[0078] like Figure 7 As shown, the control circuit connected to the first auxiliary mold opening cylinder 201 includes a hydraulic power source 2-5, a cylinder control valve block 2-7, a system control valve block 2-6, a position sensor 2-9, and a closed-loop pump flow feedback unit 2-8.

[0079] Specifically, in the control loop: Hydraulic power source 2-5, connected to system control valve block 2-6, is used to supply hydraulic oil to the first auxiliary mold opening cylinder 201. The function of hydraulic power source 2-5 is to provide a stable hydraulic oil flow to the first auxiliary mold opening cylinder 201, which is the energy basis for the system's operation; The hydraulic cylinder control valve block 2-7 is connected to the hydraulic oil input end of the first auxiliary mold opening cylinder 201 and is used to control the oil inlet and outlet of the first auxiliary mold opening cylinder 201. As a component that directly controls the first auxiliary mold opening cylinder 201, the hydraulic cylinder control valve block 2-7 is responsible for regulating the flow direction and flow rate of the hydraulic oil entering the first auxiliary mold opening cylinder 201, thereby precisely controlling the extension and retraction of the hydraulic push rod 2-1. System control valve block 2-6, connected to cylinder control valve block 2-7 and hydraulic power source 2-5, is used to regulate the hydraulic flow and pressure entering the first auxiliary mold opening cylinder 201. The function of system control valve block 2-6 is to finely regulate the hydraulic flow and pressure of the entire system. The closed-loop pump flow feedback unit 2-8 is directly connected to the hydraulic power source 2-5. Its core function is to monitor the actual flow output of the hydraulic power source 2-5 in real time and convert this key physical quantity into a feedback signal to be transmitted to the control system of the injection molding machine. Position sensor 2-9 includes a forward limit switch 2-2 and a backward limit switch 2-3. Position sensor 2-9 is connected to the hydraulic cylinder control valve block 2-7 and is used to detect the extension / retraction position of the hydraulic push rod 2-1 in real time.

[0080] like Figure 1 As shown, Figure 1 The description of the ejector assembly is based on the ejector assembly opposite to the first auxiliary mold opening cylinder 201. Since the ejector assembly opposite to the second auxiliary mold opening cylinder 202 and the ejector assembly opposite to the first auxiliary mold opening cylinder 201 have the same structure—both including an ejector and a retainer—and the structures of the ejector and retainer are identical, differing only in their placement, this embodiment will describe the ejector assembly using the one opposite to the first auxiliary mold opening cylinder 201 as an example.

[0081] Specifically, the push rod assembly includes: Top rod 5 and retainer 7.

[0082] The retainer 7 is positioned opposite the first auxiliary mold opening cylinder 201, both located on the same horizontal plane. This symmetrical layout ensures the straightness of the thrust transmission path, avoids lateral forces caused by angular deviations, thereby preventing the ejector rod from bearing unnecessary bending stress and ensuring long-term reliability.

[0083] The fixture 7 is fixedly installed on the bottom side of the operating side of the fixed template. The fixture 7 is provided with an annular fixing groove for fixing and installing the top rod 5. The inner wall surface of the annular fixing groove is provided with at least one inwardly recessed annular groove.

[0084] The ejector rod 5 is positioned opposite to the hydraulic ejector rod 2-1 of the first auxiliary mold opening cylinder 201, and at least one protruding annular buckle is provided on one end surface of the ejector rod 5, with a certain distance between two adjacent annular buckles.

[0085] The push rod assembly achieves a fixed connection between the push rod 5 and the retainer 7 by interlocking the annular buckle and the annular groove. This annular buckle and the annular groove in the retainer 7 form a classic "buckle-groove" interlocking structure. When the end of the push rod 5 with the annular buckle is inserted into the retaining groove of the retainer 7, the annular buckle will engage in the annular groove through axial pushing or slight rotation, forming a reliable mechanical connection. This connection method enables rapid assembly and disassembly, allowing for quick removal and installation while also enabling adjustment of the push rod 5's length.

[0086] In the operation of injection molding equipment, the opening, closing and locking of the moving mold plate 1 and the fixed mold plate 6 are the basic actions to ensure the normal operation of the mold and the quality of the product. The large-stroke mold closing and opening are usually undertaken by the mold opening and closing assembly. However, for the micro mold opening process that requires extremely high precision control, it is necessary to rely on the auxiliary mold opening and closing assembly and the close coordination of the mold opening and closing assembly to achieve a stable and controllable effect.

[0087] Specifically, in this embodiment, the collaborative working process of the auxiliary mold opening and closing assembly and the mold opening and closing cylinder is as follows: When gas needs to be released or foam volume controlled through micro-mold opening after injection, the injection molding machine's control system issues a command to remove the clamping force provided by the high-pressure hydraulic cylinder. Simultaneously, the mold opening and closing hydraulic cylinder on the fixed mold platen provides a locking force. This locking force precisely constrains the moving mold platen, maintaining a tight fit with the mold in the fixed mold direction, preventing the moving mold platen from completely losing its constraint. At this point, the auxiliary mold opening and closing assembly begins to operate, pushing the moving mold platen 1 to form a tiny gap under the constraint of the assembly, thus achieving micro-mold opening.

[0088] During the micro-mold opening process, the first and second mold-opening cylinders 12-2 and 12-1 provide a certain clamping force to prevent the moving mold plate 1 from shifting significantly under pressure or inertia within the mold cavity. Meanwhile, the auxiliary mold-opening assembly, under the precise control of its control circuit, transmits thrust to the fixed mold plate 6 via the ejector assembly, thereby pushing the moving mold plate 1 backward in a parallel direction to create a micro-gap. During this stage, the first and second mold-opening cylinders 12-2 and 12-1 maintain partial locking force to constrain the moving mold plate, while the auxiliary mold-opening assembly applies a controllable micro-thrust, forming a complementary relationship. The movement of the moving mold plate 1 no longer entirely depends on the large inertial motion of the mold-opening assembly, but is precisely adjusted by the auxiliary mold-opening assembly under its constraint, ensuring that the micro-gap is neither too large nor that the left and right sides are asynchronous.

[0089] Specifically, the hydraulic ejector rods of the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202 can reciprocate within the cylinder body, with one end fixed inside the piston and the other end extending out of the cylinder body surface and facing the ejector rod assembly. When hydraulic oil enters the respective cylinder bodies through the inlets of the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202, it pushes the pistons of the respective cylinders, causing the hydraulic ejector rods of the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202 to extend. As the hydraulic ejector rods gradually extend, they abut against the ejector rod assembly positioned opposite them. At this time, the ejector rod and the retainer in the ejector rod assembly ensure a stable connection through the engagement of the annular groove and the annular buckle. The gradual extension of the hydraulic ejector rods causes the moving mold plate to retract slightly under the reaction force, achieving micro-opening of the mold. The precision and speed of this extension and retraction process are entirely controlled by the control circuits of the first auxiliary mold opening cylinder 201 and the second auxiliary mold opening cylinder 202.

[0090] Specifically, taking the control circuit of the first auxiliary mold opening cylinder 201 as an example, the working process of the control circuit is as follows: First, the hydraulic power source 2-5 provides hydraulic oil at a constant pressure, which enters the first auxiliary mold opening cylinder 201 through the system control valve block 2-6. The system control valve block 2-6 dynamically adjusts the hydraulic flow and pressure according to the instructions of the control system to ensure smooth and controllable movement of the hydraulic ejector rod. The cylinder control valve block 2-6 is directly connected to the hydraulic input end of the first auxiliary mold opening cylinder 201 and the position sensors, namely the forward limit switch 2-2 and the retraction limit switch 2-3, for precise control of the oil inlet and outlet of the cylinder. As the hydraulic ejector rod of the first mold opening and closing cylinder 201 gradually extends, the position sensor 2-9 monitors the position of the hydraulic ejector rod 2-1 in real time. When the forward limit switch 2-2 in the position sensor 2-9 detects that the piston rod has reached the preset forward limit position, it immediately sends a signal to the control system to prevent the ejector rod from over-extending and causing damage to the mold; while the retraction limit switch 2-3 sends a signal when the piston rod is fully retracted to ensure that the hydraulic ejector rod 2-1 is in a safe initial position.

[0091] The closed-loop pump flow feedback unit 2-8 plays a crucial role in ensuring the stability of the hydraulic power source within the entire control loop. It continuously monitors the flow output of the hydraulic power source 2-5 and transmits the signal to the injection molding machine's control system. If the hydraulic flow fluctuates, the system control valve block 2-6 immediately compensates and adjusts, ensuring a stable and consistent flow of hydraulic oil into the auxiliary mold opening cylinder. This prevents jitter or displacement deviation of the ejector rod due to unstable flow. Through this real-time feedback and correction, the extension and retraction speed and stroke of the auxiliary mold opening cylinder can be precisely controlled, ultimately ensuring that the micro-opening gap of the moving platen remains stable within a controllable range of 0.5mm to 2mm.

[0092] Under the control loop, the auxiliary mold opening cylinder and the mold opening and closing cylinder form a mutually restrictive yet cooperative relationship. During the micro-mold opening stage, the mold opening and closing cylinder does not completely depressurize but maintains a certain locking force to prevent the moving mold plate from suddenly moving due to internal pressure or inertia. Under this constraint, the auxiliary mold opening and closing assembly slowly and precisely advances the moving mold plate. Through the simultaneous force exerted by the diagonally distributed dual cylinders, the moving mold plate 1 moves backward in parallel under the action of four force points, avoiding skewing. The forward limit switch 2-2 and the backward limit switch 2-3 continuously provide position feedback throughout the entire operation. The closed-loop pump flow feedback unit 2-8 ensures a stable hydraulic supply, while the cylinder control valve block 2-7 and the system control valve block 2-6 dynamically adjust the flow and pressure based on this feedback information.

[0093] Once the micro-mold opening process is completed, such as after gas release or foaming, the control system issues a command to slowly retract the auxiliary mold opening cylinder. Under the monitoring of the retraction limit switch 2-3, the hydraulic ejector rod 2-1 gradually retracts, disengaging from the stationary mold plate 6, and the moving mold plate 1 returns to the open state. This retraction process is also precisely controlled by the control loop to avoid impacts caused by excessively rapid oil return or stagnation caused by insufficient oil return. The entire micro-mold opening cycle is thus successfully completed, and the mold is ready to proceed to the next process.

[0094] (8) After the product has cooled and solidified, the hydraulic system drives the mold opening and closing assembly to move in the opposite direction, controlling the moving mold plate to move away from the fixed mold plate, thus realizing the mold opening. During this process, the auxiliary mold opening cylinder and the ejector rod assembly automatically reset, and the hydraulic ejector rod of the auxiliary mold opening cylinder gradually retracts under the monitoring of the return limit switch, ensuring that the moving mold plate remains stable during the large stroke mold opening.

[0095] Specifically, during the mold opening process of the injection molding machine, the coordinated working process of the mold opening and closing components is as follows: When injection molding is completed and the mold opening process begins, the directional valves of the hydraulic control valve blocks of the first mold opening / closing cylinder 12-2 and the second mold opening / closing cylinder 12-1 begin to operate. The hydraulic directional valves switch the oil circuit. At this time, the hydraulic control valve blocks control the high-pressure hydraulic oil to flow into the rod chambers of the first mold opening / closing cylinder 12-2 and the second mold opening / closing cylinder 12-1, pushing the piston towards the rodless chamber, thus causing the piston to extend outward. In this situation, the pressure direction of the hydraulic oil on the piston is opposite to that during mold closing, so the piston is forced to move in the opposite direction to the mold opening process. The piston rod gradually extends outward, driving the connected piston rod to extend forward axially, thereby pushing the moving mold platen gradually away from the fixed mold platen, completing the mold opening. During the mold opening process, the two cylinders continue to operate synchronously, applying uniform thrust to the moving mold platen from different positions above and below, ensuring a smooth and stable retraction process without any deviation or tilting.

[0096] (9) As the mold gradually separates, the product is retained on one side of the fixed or moving mold plate. At this time, the ejection mechanism operates to eject the product out of the mold cavity, completing the product removal process. After ejection, the ejector pin retracts under the action of the reset device, preparing for the next cycle.

[0097] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has disclosed the preferred embodiment as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-mentioned technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. The implementation schemes in the above embodiments can be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall still fall within the scope of this application.

Claims

1. An injection molding device with an auxiliary micro-mold opening and sealing structure, characterized in that, include: The moving template and the fixed template are set relative to each other, and together they form the injection mold. The mold opening and closing assembly includes a first mold opening and closing cylinder disposed on the top side of the operating side of the fixed mold plate and a second mold opening and closing cylinder disposed on the bottom side of the non-operating side of the fixed mold plate. The piston rod of the mold opening and closing cylinder extends along the direction of the moving mold plate and is fixedly connected to the corresponding mounting hole of the moving mold plate. An auxiliary mold opening assembly includes an auxiliary mold opening cylinder assembly and a push rod assembly disposed opposite to the auxiliary mold opening cylinder assembly; the auxiliary mold opening cylinder assembly includes a first auxiliary mold opening cylinder disposed on the bottom side of the operating side of the moving mold plate and a second auxiliary mold opening cylinder disposed on the top side of the non-operating side of the moving mold plate; the push rod assembly is fixed to the side of the bottom side of the operating side of the fixed mold plate and the side of the top side of the non-operating side of the fixed mold plate, respectively; the auxiliary mold opening cylinder assembly and the mold opening and closing assembly are arranged diagonally in a vertical plane. The injection screw is located in the center of the barrel; An injection cylinder, which is connected to the injection screw, is used to drive the injection screw to achieve reciprocating linear motion and rotation; An active back pressure unit, the hydraulic power source of which is connected to the control circuit of the injection cylinder, is used to apply a reverse force to the injection cylinder after the screw plasticizing and metering is completed, so as to maintain the stability of the pressure at the head of the injection screw and ensure the accuracy of the material level of the injection screw; The sealing structure is set on the parting surface of the injection mold formed between the moving template and the fixed template.

2. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 1, characterized in that, The auxiliary mold opening cylinder includes: The main body of the hydraulic cylinder is fixedly mounted on a bracket on one side of the moving template by screws; A hydraulic push rod has one end fixed inside the cylinder body and the other end extending out of the cylinder body surface. The hydraulic push rod can slide back and forth inside the cylinder body to directly apply the thrust output by the cylinder body to the push rod assembly to achieve micro-opening of the moving template. The forward limit switch and the reverse limit switch are respectively located at both ends of the top of the cylinder body and connected to the control circuit, used to detect the stroke limit of the piston rod and provide feedback signals; The control circuit is connected to the auxiliary mold opening cylinder.

3. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 2, characterized in that, The control loop includes: A hydraulic power source is connected to the system control valve block and the auxiliary mold opening cylinder respectively, and is used to provide hydraulic oil to the auxiliary mold opening cylinder; The hydraulic cylinder control valve block is connected to the hydraulic input end of the auxiliary mold opening cylinder and the forward limit switch and the backward limit switch, respectively. It is used to control the oil inlet and return of the auxiliary mold opening cylinder and to detect the extension and retraction position of the piston rod in real time and feed it back to the control system. The system control valve block is connected to the cylinder control valve block and to the hydraulic power source, and is used to regulate the hydraulic flow and pressure entering the auxiliary mold opening cylinder; The position sensor, which is a forward limit switch and a backward limit switch, is connected to the hydraulic cylinder control valve block and is used to detect the extension and retraction position of the hydraulic push rod in real time and feed it back to the control system. A closed-loop pump flow feedback unit is connected to the hydraulic power source and is used to monitor the flow output of the hydraulic power source in real time and transmit the feedback signal to the control system.

4. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 2, characterized in that, The detection signal from the position sensor is input to the control system, which controls the stroke and speed of the auxiliary mold opening cylinder so that the micro-opening distance of the moving mold plate is kept within a controllable range of 0.5mm-2mm.

5. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 2, characterized in that, The push rod assembly includes: A fixture is provided opposite to the auxiliary mold opening cylinder and is located on the same horizontal line as the auxiliary mold opening cylinder. The fixture is fixedly installed on one side of the fixed template. A fixing groove is provided at the center of the fixture, and at least one inwardly recessed annular groove is provided on the inner surface of the fixing groove. A push rod is disposed opposite to the hydraulic push rod. One end of the push rod has at least one protruding annular buckle. The push rod is fixedly connected to the fixture by engaging with the annular buckle and the annular groove. The other end of the push rod extends along the direction of the moving template.

6. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 1, characterized in that, The injection screw includes: The screw head has a check ring at its front end to prevent molten material from flowing back during injection; the side of the check ring facing the tail of the screw has a mixing and dispersing section and a metering section in sequence. The tail end of the screw is connected to the injection cylinder of the injection molding machine via a spline, thereby realizing the reciprocating linear motion and rotation of the injection screw under the drive of the injection cylinder.

7. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 6, characterized in that, The metering section mainly consists of screw ridges and screw grooves arranged along the axial direction of the injection screw.

8. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 7, characterized in that, The spiral edges are spirally distributed and extend continuously along the axial direction of the injection screw, and at least one spiral groove is formed between the spiral edges and the injection screw body.

9. An injection molding device with an auxiliary micro-mold opening and sealing structure according to claim 6, characterized in that, The mixing and dispersing section of the screw head, starting from the section closest to the metering section, includes, from front to back, the following: The spiral dispersing element area is used to break up and disperse gas components during material flow and to convey initially dispersed molten material. The pin mixing zone, located after the spiral dispersing element zone, is used to further stir and homogenize the gas-containing molten material, thereby forming a homogeneous melt.

10. An injection molding device with an auxiliary micro-mold opening and sealing structure according to claim 9, characterized in that, The surface of the spiral dispersing element region is provided with at least one shallow groove along the screw axis to maintain the spiral guiding effect when the material moves forward, avoid local stagnation, and form a stable laminar flow distribution.

11. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 10, characterized in that, The depth of the shallow trench is 0.2-0.4 mm.

12. An injection molding device with an auxiliary micro-mold opening and sealing structure according to claim 6, characterized in that, A smooth transition zone is also provided between the metering section and the spiral dispersing element area.

13. An injection molding device with an auxiliary micro-mold opening and sealing structure according to claim 12, characterized in that, The length of the smooth transition zone is 0.5-1.0 times the diameter of the spiral dispersion element section.

14. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 6, characterized in that, The pin mixing zone includes at least one guide ring arranged along the screw axis, and at least three radially protruding pins are provided on the guide ring, the pins being arranged obliquely relative to the screw axis on the guide ring.

15. An injection molding device with an auxiliary micro-mold opening and sealing structure according to claim 6, characterized in that, The screw head is connected to the locking nozzle of the injection molding machine to allow the melt to enter the injection mold cavity during the injection stage and to prevent the melt from flowing back during the plasticizing stage.

16. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 1, characterized in that, The sealing structure is disposed around the parting surface of the injection mold, and includes: A thin-walled region, the thickness of which is 0.8-1.2 mm, is used to allow the molten plastic to cool and solidify rapidly in this region after injection. A cooling barrier zone, which is formed by extending the thin-walled zone outward from the parting surface, has a width of at least 1.5-2 times the mold foam thickness.

17. The injection molding device with auxiliary micro-mold opening and sealing structure according to claim 1, characterized in that, Also includes: A high-pressure hydraulic cylinder assembly, comprising four high-pressure hydraulic cylinders arranged in a rectangular symmetrical manner at the four corners of the moving template away from the fixed template; A lock-up nozzle is located between the barrel head and the injection mold gate. The lock-up nozzle is fixedly connected to the barrel via a flange. It is used to open under hydraulic drive during the injection stage to allow the melt to be injected into the mold cavity, and to close during the plasticizing and back pressure stages to ensure metering and prevent melt backflow. It is used to open hydraulically during the injection stage to allow the melt to enter the mold cavity, and to close during the plasticizing and back pressure stages to prevent melt backflow.

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