An injection unit for a two-stage venting injection molding machine to prevent material overflow.

Abstract

This invention discloses an injection unit for a two-stage venting injection molding machine with anti-overflow design, comprising a first-stage drive unit, a first-stage injection connector, a transition connector, a first-stage injection barrel and screw, a right-angle reversing head, a connecting channel, a heater, a second-stage drive unit, a second-stage injection connector, a second-stage injection barrel and plunger, a three-way valve flange, a three-way valve core assembly, a nozzle flange, and a nozzle. The three-way valve core assembly includes a two-position three-way valve core, a guide cover, a cooling connecting shaft, and a valve core drive unit. The first-stage barrel screw performs the pre-plasticizing function, while the second-stage barrel plunger performs the material storage and injection functions. Vent holes are provided on the first-stage barrel to discharge moisture and other volatiles during the pre-plasticizing process. This invention, through the designed two-position three-way valve core assembly, can precisely control the melt flow path during the pre-plasticizing and injection processes respectively. Allowing the melt to flow out from the rear of the plunger and both sides of the two-position three-way valve core not only solves the melt accumulation problem but also allows the melt to act as a lubricant.

Description

Technical Field

[0001] This invention relates to the field of injection molding machine technology, and particularly to a plasticizing and injection device for a vented injection molding machine. Background Technology

[0002] In the standard injection molding production process, to effectively reduce or completely eliminate moisture and other volatile gaseous components inside the raw materials, it is usually necessary to dry the raw materials for several hours before starting the injection molding process. This process requirement necessitates the use of auxiliary equipment such as dryers and dehumidifiers during production, which significantly increases the cost of injection molding machine accessories and also results in a high overall energy consumption level for injection molding production equipment.

[0003] The design concept of a vented injection molding machine cleverly integrates the raw material drying process into the pre-plasticizing process. During the operation of the vented injection molding machine, the shearing and stirring action of the barrel and screw, combined with the high-temperature environment inside the barrel, promotes the melting of raw materials containing moisture and other volatile components. In this process, the volatile components in the raw material form numerous tiny bubbles. As the screw channel depth changes, the melt pressure instantly changes from a high-pressure state to a low-pressure state, causing the volatile bubbles inside the melt to rapidly expand and burst, ultimately being discharged smoothly from the vent of the barrel, thus obtaining a pure melt free of gas.

[0004] However, most vented injection molding machines on the market currently use a reciprocating screw structure. Because these machines have three different pressure zones—high pressure, low pressure, and high pressure—sequentially along the material flow direction, material leakage from the vent often occurs during actual production. Once leakage occurs, regular cleaning is required. Furthermore, if the leakage accumulates over a long period, carbonization will occur. The carbonized layer is prone to detachment and mixing into the melt, resulting in black spots and defects on the surface of the injection molded products. This not only reduces the production line's efficiency but also seriously affects the quality of the finished products.

[0005] Furthermore, during the discharge process of a reciprocating screw injection molding machine, the screw undergoes a retraction motion, continuously moving in the opposite direction of material flow, while the position of the barrel vent remains fixed. This results in the venting position of the material constantly changing during actual production, causing differences in the venting effect of the material passing through the vent at different times, thus affecting the uniformity of the melt.

[0006] In view of the above problems, this invention, with its innovative thinking, proposes a plasticizing and injection device for a vented two-stage injection molding machine, aiming to effectively solve many problems existing in the current reciprocating screw vented injection molding machine and improve the efficiency of injection molding production and the quality of products. Summary of the Invention

[0007] To address the above problems, this invention innovatively proposes a plasticizing and injection device for a vented two-stage injection molding machine. It employs a screw-plasticor type injection device where the screw does not participate in the reciprocating injection motion, ensuring a fixed venting position, consistent melt uniformity, and preventing leakage, accumulation, and carbonization during the plasticizing stage. While utilizing the plunger as the injection mechanism, the plunger's structure allows the melt to penetrate from the center outwards in the injection section, preventing dead zones and accumulation in the flow channel. Simultaneously, the melt lubricates the plunger.

[0008] To achieve the above functions, the technical solution adopted by this invention is as follows: A plasticizing and injection device for a vented two-stage injection molding machine, comprising a first-stage drive device, a first-stage injection connector, a transition connector, a first-stage injection barrel and screw, a right-angle reversing head, a connecting channel, a heater, a second-stage drive device, a second-stage injection connector, a second-stage injection barrel and plunger, a three-way valve flange, a three-way valve core assembly, a nozzle flange, and a nozzle. The three-way valve core assembly includes a two-position three-way valve core, a guide cover, a cooling connecting shaft, and a valve core drive device, among other components. Its main feature is that the first-stage barrel screw performs the pre-plasticizing function, and the first-stage screw only rotates; the second-stage barrel plunger performs the material storage and injection function, and the second-stage plunger only reciprocates linearly. During production, the first-stage drive device causes the first-stage screw to rotate for pre-plasticizing. A vent is provided on the first-stage barrel, connected to an exhaust system or air, to discharge moisture and other volatiles generated during the pre-plasticizing process. The plasticized melt continues to move forward, passing through the right-angle reversing head and connecting channel downwards, entering the second-stage barrel for storage. At this time, the three-way valve core assembly is in the pre-plasticizing position, connecting only the second-stage barrel and the connecting channel. After the pre-plasticizing action is completed, the three-way valve core assembly switches to the injection position, connecting the nozzle and the second-stage barrel while closing the connecting channel. At this time, the second-stage drive device causes the second-stage plunger to move linearly to complete the injection action. Compared with ordinary vented injection molding machines, the device structure of this invention uses a two-stage barrel and screw to perform the pre-plasticizing and injection functions respectively, eliminating the relative change between the vent position and the screw, and blocking the transmission process of high melt pressure to the vent position during injection, thus improving the performance of the vented injection molding machine.

[0009] The first-stage injection unit and the second-stage injection unit are arranged vertically. The first-stage injection unit conveys, melts, and stirs the plastic raw material, and connects to the relevant exhaust system to remove moisture and other volatiles from the molten plastic raw material. The second-stage injection unit stores and injects the plastic raw material. The plastic raw material enters the second-stage injection unit for temporary storage. After storage, the three-way valve core assembly station is switched, and then the second-stage injection unit injects the molten plastic raw material into the mold for forming.

[0010] A first-stage injection molding unit for pre-plasticizing includes a first-stage drive unit, a first-stage injection connector, a first-stage injection barrel and screw, a right-angle reversing head, a connecting channel, and heaters. The first-stage drive unit connects to the first-stage injection screw, transmitting rotational power to the screw for material pre-plasticizing. The first-stage drive unit, first-stage injection barrel, and corresponding feeding equipment are all mounted on the first-stage injection connector. Several heaters are installed on the first-stage injection barrel, forming an assembly similar to the injection unit of a conventional injection molding machine. The first-stage injection screw is placed inside the first-stage injection barrel. The right-angle reversing head connects both the first-stage injection barrel and the connecting channel, guiding the melt downwards. Heaters are also installed on the connecting channel to maintain the temperature of the molten plastic material and prevent solidification.

[0011] A two-stage injection unit for material storage and injection includes a two-stage drive unit, a two-stage injection connector, a two-stage injection barrel and plunger, a three-way valve flange, a three-way valve core assembly, a nozzle flange, a nozzle, and heaters. The two-stage drive unit, connected to the two-stage injection plunger, transmits linear motion power to the plunger for material storage and injection. The two-stage drive unit and the two-stage injection barrel are mounted together on the two-stage injection connector. Several heaters are installed on the two-stage injection barrel, and the two-stage injection plunger is placed inside the barrel. The three-way valve flange is mounted on the two-stage injection barrel. The three-way valve core assembly, nozzle flange, and connecting channel are all mounted on the three-way valve flange, enabling flow channel communication control during both pre-plasticizing and injection operations. The nozzle is mounted on the nozzle flange, forming the nozzle section of a conventional injection molding machine for injection.

[0012] The first-order drive device includes a power source, a reducer, a connecting flange, a coupling, and a coupling connection. The power source is connected to the reducer, the reducer is mounted on the connecting flange, and the output shaft of the reducer is connected to the coupling connection via the coupling.

[0013] The second-stage drive device includes a hydraulic cylinder and a connecting bushing.

[0014] Furthermore, the coupling is equipped with a deep groove ball bearing, and thrust bearings and angular contact ball bearings can be added as needed to match the installation form of the injection molding machine motor seat that matches the same specification screw, so that it has good interchangeability.

[0015] Furthermore, the connecting flange is provided with an installation port and an oil injection hole. During installation, the coupling screws are tightened through the installation port, and lubricating medium is added through the oil injection hole to lubricate the bearing.

[0016] Furthermore, the first-stage injection connector is provided with cooling water channels to prevent overheating of the first-stage injection barrel feeding section.

[0017] Furthermore, the first-stage injection connector and the second-stage injection connector are installed together through a transition connector to form a two-stage injection molding machine structure with vertical distribution.

[0018] Furthermore, the connecting channel and transition connector have multiple specifications and can be replaced according to the center height of different models to jointly ensure the level of the first-order injection device.

[0019] Furthermore, a discharge port is provided below the second-stage injection barrel.

[0020] Furthermore, the second-stage injection plunger is provided with lubrication grooves arranged along its own axial direction, so that it can be lubricated by the melt itself during long-term use, avoiding damage to the internal second-stage injection barrel, and preventing the formation of a dead zone on the rear side of the plunger, which would cause material to accumulate and carbonize, affecting the quality of the product.

[0021] Furthermore, the second-stage injection plunger has five lubrication grooves, and the spacing between the lubrication grooves is consistent with the width of the screw thread of the same diameter specification.

[0022] The three-way valve core assembly includes components such as a two-position three-way valve core, a guide cover, a cooling connecting shaft, and a valve core drive device. The two-position three-way valve core has two stations. One station connects to the upper connecting channel and the second-stage injection cylinder, and the other station connects to the nozzle and the second-stage injection cylinder. The flow channel is controlled by switching the stations.

[0023] Furthermore, the two-position three-way valve core is provided with an injection channel and a pre-plasticizing channel, the injection channel connecting the front and the rear, and the pre-plasticizing channel connecting the top and the rear.

[0024] Furthermore, the two-position three-way valve core is also provided with lubrication grooves distributed along the axial direction. Since the assembly gap between the two-position three-way valve core and the valve core hole of the three-way valve flange is between 0.08 and 0.1 mm, during the long-term use of the injection molding device, a small amount of polymer melt will seep out along the assembly gap, remain briefly in the lubrication groove, play a lubricating role, and eventually continue to flow out to both sides of the two-position three-way valve core, instead of flowing back into the main channel.

[0025] Furthermore, the two-position three-way valve core has five lubrication grooves, and the total length formed by the lubrication grooves and their intervals is consistent with the maximum moving distance of the two-position three-way valve core.

[0026] Furthermore, a guide spline is provided on one side of the two-position three-way valve core, and the guide cover is installed on the flange of the three-way valve near the guide spline of the two-position three-way valve core and cooperates with it to prevent the two-position three-way valve core from rotating around its own axis of motion during reciprocating motion.

[0027] Furthermore, a discharge port is provided below the guide cover.

[0028] Furthermore, a cooling water channel is provided on the cooling connecting shaft to prevent the high temperature on one side of the barrel flange from being conducted to the valve core drive device on the other side.

[0029] The injection device is mounted entirely on the frame.

[0030] Compared with the prior art, the present invention has significant advantages, specifically in the following aspects: (1) Effectively avoids material overflow: The present invention, through its innovatively designed two-position three-way valve core assembly, can precisely control the melt flow path during the pre-plasticizing and injection processes. During injection, this assembly can effectively prevent the melt pressure from being transmitted to the low-pressure area of ​​the venting section, thereby completely avoiding the material overflow phenomenon commonly seen in existing venting injection molding machines during production, and greatly improving the stability and continuity of production.

[0031] (2) Improved melt quality consistency: The vented injection molding machine proposed in this invention has no relative movement between the vent and the screw. This unique design ensures that the material remains in the same position as it passes through the vent, thus significantly improving the consistency of the melt quality obtained from the pre-plasticized melt. At the same time, since the instability caused by relative movement is eliminated, material overflow is also greatly reduced, further ensuring the reliability of the production process.

[0032] (3) Lubrication Function: This invention allows the melt to flow out from the rear of the plunger and also from both sides of the two-position three-way valve core. This design not only effectively solves the problem of melt accumulation but also gives the melt the additional function of acting as a plunger lubricant. The distribution and structural dimensions of the lubrication grooves have been optimized. The distribution of the lubrication grooves on the plunger is based on the width of the screw thread of the same specification, and the distribution of the lubrication grooves on the two-position three-way valve core is based on the movement stroke of the valve core itself. Targeted adjustments are made when matching different machine models and processing different materials to improve performance. Through this ingenious design, not only is the frictional resistance during the plunger's movement reduced, extending the service life of the equipment, but also the maintenance cost of the equipment is lowered.

[0033] (4) Multifunctional vent design: The vent of this invention adopts an inclined arrangement. This design not only achieves stable venting but also has a variety of additional functions. On the one hand, it can serve as a visual window, allowing operators to observe the state of the melt at any time and promptly identify and resolve potential problems. On the other hand, the inclined vent also facilitates sampling operations and provides convenient conditions for the installation of other equipment, enhancing the practicality and scalability of the equipment.

[0034] (5) No Dead Zones in Melt Flow Channel: The venting injection molding machine proposed in this invention has no dead zones in the melt flow channel, especially at the two-position three-way valve core and the plunger. Through the design of reserved gaps, a very small amount of melt can flow out at these points, and a discharge port is provided for convenient and timely cleaning. At the selected gap size, this flow rate does not affect the final output of the injection molding machine and will not cause excessive material loss. The material will be continuously renewed at a slow speed at the locations where dead zones are prone to form. In this way, the long-term accumulation and scorching of melt in local areas is avoided.

[0035] (6) Good machine compatibility: The vented injection molding machine proposed in this invention can be well matched with existing models. By changing the connecting channel and transition connecting seat, the center height of the equipment can be flexibly adjusted to adapt to different production needs and working environments. This height adaptability makes the vented injection molding machine of this invention have a wider range of application prospects and can provide users with more convenient and efficient production solutions. (7) Simplified structure and reduced manufacturing difficulty: This invention abandons the relatively large injection seat and motor seat castings in traditional vented injection molding machines and adopts a simpler structural design. This improvement not only makes the overall structure of the equipment more compact and reasonable, but also significantly reduces the manufacturing difficulty and production cost. At the same time, the simplified structure is also conducive to improving the installation and maintenance efficiency of the equipment and reducing the user's operating costs.

[0036] (8) Optimized assembly dimensions and reduced space occupancy: This invention no longer adopts the dual-cylinder injection structure, but achieves a significant reduction in overall assembly dimensions through optimized design. This allows the vented injection molding machine of this invention to maintain high-efficiency performance while occupying less space. For production sites with limited space, this low space occupancy design has significant practical value, helping users to plan and utilize production space more rationally. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the injection device of a two-stage venting injection molding machine for preventing material overflow according to the present invention;

[0038] Figure 2 This is a cross-sectional view of the injection device of a two-stage venting injection molding machine for preventing material overflow, according to the present invention.

[0039] Figure 3 This is a schematic diagram of the internal structure of the first-stage drive device of the injection unit of a two-stage venting injection molding machine for preventing material overflow, according to the present invention. The viewing direction is... Figure 2 From left to right;

[0040] Figure 4 This is a schematic diagram of the key structural features of some parts of the injection device of a two-stage venting injection molding machine for preventing material overflow according to the present invention;

[0041] Figure 5 This is a schematic diagram of the key structural features of the three-way valve core assembly and some parts of the injection device of a two-stage venting injection molding machine for preventing material overflow, according to the present invention. The viewing direction is... Figure 2 From right to left;

[0042] Figure 6 This is a schematic diagram of the three-way valve flange, connecting channel, and three-way valve core assembly of the injection device of a two-stage venting injection molding machine for preventing material overflow in the pre-plasticizing state, as per the present invention. The viewing direction is... Figure 2 From left to right;

[0043] Figure 7 This is a schematic diagram of the three-way valve flange, connecting channel, and three-way valve core assembly of the injection device of a two-stage venting injection molding machine for preventing material overflow, as per the present invention, in the injection state. The viewing direction is... Figure 2 From left to right.

[0044] In the diagram: 100 - First-stage injection unit; 200 - Second-stage injection unit; 110 - First-stage drive unit; 120 - First-stage injection connector; 120a - Cooling channel for first-stage injection connector; 130 - Transition connector; 140 - First-stage injection barrel; 140a - Exhaust port for first-stage injection barrel; 150 - First-stage injection screw; 160 - Right-angle reversing head; 160a - Internal flow channel for right-angle reversing head; 170 - Connecting channel; 180 - Heater for first-stage injection unit; 210 - Second-stage drive unit; 220 - Second-stage injection connector; 230 - Second-stage injection barrel; 230a - Discharge port for second-stage injection barrel; 240 - Second-stage injection plunger; 240a - Lubrication groove for second-stage injection plunger; 250 - Three-way valve flange; 250a - Material storage channel for three-way valve flange; 250b - Pre-plasticizing channel for three-way valve flange; 250c - Three-way valve flange injection channel; 260-Three-way valve core assembly; 270-Injector flange; 280-Injector; 111-Power source; 112-Reducer; 113-Connecting flange; 113a-Connecting flange mounting port; 113b-Connecting flange oil injection hole; 114-Coupling; 115-Coupling connection; 211-Hydraulic cylinder; 212-Connecting bushing; 261-Two-position three-way valve core; 261a-Two-position three-way valve core 261b - Lubrication groove for 2-position 3-way valve core; 261c - Pre-plasticized flow channel for 2-position 3-way valve core; 261d - Injection flow channel for 2-position 3-way valve core; 262 - Guide cap; 262a - Discharge port for guide cap; 262b - Guide spline for guide cap; 263 - Cooling connecting shaft; 263a - Cooling water channel for cooling connecting shaft; 264 - Valve core drive device; 265 - Positioning plate; 266 - Connecting rod. Detailed Implementation

[0045] The present invention is further illustrated below through specific implementation examples. The following description is merely a portion of the embodiments; any other embodiments obtained by making non-inventive substitutions or modifications based on the embodiments of the present invention are within the protection scope of the present invention.

[0046] In the description of this invention, the terms “center,” “upper side,” “lower side,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “front,” and “rear,” etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, structure, or operation. Therefore, they should not be construed as limitations on this invention.

[0047] In the description of this invention, injection molding machine components or parts not included in the illustrations, such as heaters, screws, nuts, hydraulic cylinders, hoppers, valve blocks, wiring, etc., are merely simplifications and omissions made for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to does not require these additional components to perform its function in this invention, and therefore should not be construed as a limitation of this invention.

[0048] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "communication" should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. A drive device can be electrically driven or hydraulically driven. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] The present invention will be further described below with reference to the accompanying drawings:

[0050] This invention proposes a plasticizing and injection device for a vented two-stage injection molding machine, as shown in the attached figure. Figure 1 As shown in the figure. The device mainly includes a first-stage injection unit 100 and a second-stage injection unit 200. The first-stage injection unit 100 conveys and plasticizes the material, while the second-stage injection unit 200 temporarily stores and injects the material.

[0051] As attached Figure 2As shown, the first-stage injection unit 100 for pre-plasticizing includes a first-stage drive unit 110, a first-stage injection connector 120, a transition connector 130, a first-stage injection barrel 140, a screw 150, a right-angle reversing head 160, a connecting channel 170, and a heater 180. The first-stage drive unit 110 connects to the first-stage injection screw 150, transmitting rotational power to the screw 150 for material pre-plasticizing. The first-stage drive unit 110, the first-stage injection barrel 140, and corresponding feeding equipment are all mounted on the first-stage injection connector 120. Several heaters 180 are installed on the first-stage injection barrel 140, forming an assembly similar to the injection unit of a conventional injection molding machine. The first-stage injection screw 150 is placed inside the first-stage injection barrel 140. The first-stage injection barrel 140 is provided with an exhaust port 140a for discharging gases and volatiles from the melt. The right-angle reversing head 160 is connected to both the first-stage injection barrel 140 and the connecting channel 170, guiding the melt to flow downwards. A heater 180 is also installed on the connecting channel 170 to maintain the temperature of the molten plastic raw material and prevent it from solidifying.

[0052] As attached Figure 2 As shown, a two-stage injection device 200 for material storage and injection includes a two-stage drive unit 210, a two-stage injection connector 220, a two-stage injection cylinder 230 and plunger, a three-way valve flange 250, a three-way valve core assembly 260, a nozzle flange 270, a nozzle 280, and a heater 290. The two-stage drive unit 210 is connected to the two-stage injection plunger 240, transmitting linear motion power to the plunger 240 for material storage and injection. The two-stage drive unit 210 and the two-stage injection cylinder 230 are jointly mounted on the two-stage injection connector 220. Several heaters 290 are installed on the two-stage injection cylinder 230, and the two-stage injection plunger 240 is placed inside the cylinder. The two-stage injection cylinder 230 is provided with a discharge port 230a. The three-way valve flange 250 is mounted on the second-stage injection barrel 230. The three-way valve core assembly 260, nozzle flange 270, and connecting channel 170 are all mounted on the three-way valve flange 250 to achieve flow channel communication control during the pre-plasticizing and injection operations. The nozzle 280 is mounted on the nozzle flange 270, forming the conventional injection nozzle 280 section for injection.

[0053] As attached Figure 3As shown, the first-stage drive unit 110 consists of a power source 111, a reducer 112, a connecting flange 113, a coupling 114, and a coupling link 115. The reducer 112 adjusts the output torque and speed of the power source 111 to approximately the required range for the matching first-stage injection screw 150, and then controls the output of the power source 111 for real-time fine-tuning according to actual conditions. The coupling 114 is used to compensate for the concentricity error between the output shaft of the reducer 112 and the input end of the coupling link 115. A deep groove ball bearing is installed on the coupling link 115, similar to the structure of the coupling link 115 of a conventional reciprocating screw injection molding machine. Angular contact ball bearings and thrust bearings can be added according to actual needs. The connecting flange 113 has an installation port 113a and an oil injection hole 113b. During installation, the coupling 114 screws are tightened through the installation port 113a, and lubricating medium is added through the oil injection hole 113b to lubricate the internal bearings.

[0054] As attached Figure 4 As shown, a cooling water channel 120a is provided on the first-stage injection connector 120 to prevent the feeding section of the first-stage injection barrel 140 from overheating.

[0055] As attached Figure 4 As shown, the second-stage drive device 210 consists of a hydraulic cylinder 211 and a connecting bushing 212. (See attached diagram) Figure 4 As shown, the internal flow channel 160a of the right-angle reversing head is 90°, guiding the melt downward into the second-stage injection device 200.

[0056] As attached Figure 4 As shown, the second-stage injection barrel 230 is provided with a discharge port 230a, which is used to discharge and remove a small amount of overflow melt during long-term use.

[0057] As attached Figure 4 As shown, the second-stage injection plunger 240 has several lubrication grooves 240a arranged along its own axial direction, so that the melt can play a lubricating role after entering the lubrication groove 240a, thus avoiding damage to the inside of the second-stage injection barrel 230.

[0058] As attached Figure 5As shown, the three-way valve core assembly 260 consists of a two-position three-way valve core 261, a guide cover, a cooling connecting shaft 263, a valve core drive device 264, a positioning plate 265, and a connecting rod 266. The valve core drive device 264 controls the two-position three-way valve core 261 to be in either the pre-plasticizing or injection position according to actual working conditions, enabling the blocking of high injection pressures. The two-position three-way valve core 261 is provided with a lubrication groove 261a for lubricating the sliding motion between itself and the three-way valve flange 250; it also has a guide spline 261b to prevent rotation during long-term use, which could block the flow channel. The two-position three-way valve core 261 is also provided with a pre-plasticizing flow channel 261c and an injection flow channel 261d for switching functions between different positions. The guide cover also has a guide spline 262b inside, which mates with the guide spline 261b of the two-position three-way valve core 261; the guide cover also has a discharge port 262a to facilitate the discharge and cleaning of the molten plastic flowing out along the lubrication groove 261a. The cooling connecting shaft 263 has a cooling water channel 263a to prevent the high temperature of the two-position three-way valve core 261 from being transferred to the valve core drive device 264. (See attached...) Figure 6 As shown, the three-way valve flange 250 is provided with a material storage channel 250a, a pre-plasticizing channel 250b, and an injection channel 250c.

[0059] In one specific embodiment, the two-position three-way valve core 261 is initially in the pre-plasticizing position under the action of the valve core drive device 264. At this time, the first-stage injection barrel 140, the right-angle reversing head 160, and the connecting channel 170 are connected to the second-stage injection barrel 230. Under the action of the first-stage drive device 110, the first-stage injection screw 150 rotates, conveying the undried material forward to melt it. When the material moves forward to the vent port 140a, due to the change in the screw groove of the vent screw, the material melt is depressurized, the gas escapes, and it continues to move forward into the right-angle reversing head 160.

[0060] As attached Figure 2 and appendix Figure 6 As shown, after passing through the right-angle reversing head 160, the melt changes direction and enters the connecting channel 170, then enters the pre-plasticizing channel 250b of the three-way valve flange 250, then enters the pre-plasticizing channel 261c of the two-position three-way valve core 261, and finally enters the second-stage injection barrel 230 through the storage channel 250a of the three-way valve flange 250. At this time, the second-stage drive device 210 controls the second-stage injection plunger 240 to move backward, completing the storage action.

[0061] As attached Figure 2 and appendix Figure 7As shown in the embodiment, after pre-plasticization is completed, the two-position three-way valve core 261 is changed to the injection station under the action of the valve core drive device 264. At this time, the two-stage injection barrel 230, the nozzle flange 270, and the nozzle 280 are connected. Under the action of the two-stage drive device 210, the two-stage injection plunger 240 moves forward under high pressure, pushing the melt in the two-stage injection barrel 230 into the storage channel 250a of the three-way valve flange 250, then through the injection channel 250c of the two-position three-way valve core 261, and continues to move forward into the injection channel 250c of the three-way valve flange 250. Finally, it enters the mold through the nozzle flange 270 and the nozzle 280 to complete the injection action and hold the pressure.

[0062] In this embodiment, during long-term continuous production, a small amount of melt will be discharged from the guide cover discharge port 262a and the second-stage injection barrel discharge port 230a to avoid the formation of material dead zones inside the melt flow channel.

[0063] In this embodiment, different sizes of connecting channels 170 and transition connecting seats 130 can be selected according to the specifications of the screw and plunger and the size of the matching machine model to adjust the center height of the first-stage injection device 100 and the second-stage injection device 200.

[0064] Obviously, the above-described embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description, and it is neither necessary nor possible to exhaustively list all possible implementations. However, these obvious variations or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. An injection device for a two-stage venting injection molding machine with anti-overflow properties, characterized in that: The system includes a first-stage drive unit, a first-stage injection connector, a transition connector, a first-stage injection barrel and screw, a right-angle reversing head, a connecting channel, a heater, a second-stage drive unit, a second-stage injection connector, a second-stage injection barrel and plunger, a three-way valve flange, a three-way valve core assembly, a nozzle flange, and a nozzle. The three-way valve core assembly includes a two-position three-way valve core, a guide cover, a cooling connecting shaft, and valve core drive unit components. The first-stage barrel and screw perform pre-plasticizing functions, rotating only. The second-stage barrel and plunger perform material storage and injection functions, reciprocating only linearly. The first-stage drive unit rotates the first-stage screw for pre-plasticizing. An exhaust port is provided on the first-stage barrel, connected to an exhaust system or air, to remove moisture and other pollutants generated during the pre-plasticizing process. Other volatiles are discharged; the plasticized melt continues to move forward, passing through the right-angle reversing head and connecting channel downwards, entering the second-stage barrel storage; the first-stage injection unit and the second-stage injection unit are arranged vertically. The first-stage injection unit includes a first-stage drive unit, a first-stage injection connecting seat, a first-stage injection barrel and screw, a right-angle reversing head, a connecting channel, and a heater. Through the connection between the first-stage drive unit and the first-stage injection screw, rotational power is transmitted to the first-stage injection screw for material pre-plasticization; the first-stage drive unit, the first-stage injection barrel, and the corresponding feeding equipment are all installed on the first-stage injection connecting seat. Several heaters are installed on the first-stage injection barrel, and the first-stage injection screw is placed inside the first-stage injection barrel; the right-angle reversing head connects the first-stage injection barrel and the connecting channel simultaneously. The connecting channel guides the melt to flow downwards. A heater is also installed on the connecting channel to maintain the temperature of the molten plastic raw material and prevent solidification. The second-stage injection unit includes a second-stage drive unit, a second-stage injection connector, a second-stage injection barrel and plunger, a three-way valve flange, a three-way valve core assembly, a nozzle flange, a nozzle, and heaters. The second-stage drive unit connects to the second-stage injection plunger, transmitting linear motion power to the plunger for material storage and injection. The second-stage drive unit and the second-stage injection barrel are mounted together on the second-stage injection connector. Several heaters are installed on the second-stage injection barrel, and the second-stage injection plunger is placed inside the barrel. The three-way valve flange is mounted on the second-stage injection barrel. The three-way valve core assembly, nozzle flange, and connecting channel are all mounted together on... The three-way valve flange enables flow channel communication control during pre-plasticizing and injection operations. The nozzle is installed on the nozzle flange, forming the injection nozzle section of a conventional injection molding machine for injection. The two-position three-way valve core also has axially distributed lubrication grooves. The assembly clearance between the two-position three-way valve core and the valve core hole of the three-way valve flange is between 0.08 and 0.1 mm. The two-position three-way valve core has 5 lubrication grooves, and the total length formed by the lubrication grooves and their intervals is consistent with the maximum moving distance of the two-position three-way valve core. A guide spline is provided on one side of the two-position three-way valve core. The guide cover is installed on the three-way valve flange near the guide spline of the two-position three-way valve core and cooperates with it to prevent the two-position three-way valve core from rotating around its own axis of motion during reciprocating motion.

2. The injection device of the anti-overflow dual-stage venting injection molding machine according to claim 1, characterized in that: The first-stage injection connector and the second-stage injection connector are installed together through a transition connector to form a two-stage injection molding machine structure with vertical distribution; the connecting channel and the transition connector have multiple specifications and can be replaced according to the center height of different machine models to ensure that the first-stage injection device is horizontal; a discharge port is provided below the second-stage injection barrel.

3. The injection device of the anti-overflow dual-stage venting injection molding machine according to claim 1, characterized in that: The second-stage injection plunger is provided with lubrication grooves arranged along its own axial direction. There are 5 lubrication grooves on the second-stage injection plunger, and the spacing between the lubrication grooves is consistent with the width of the screw thread of the same diameter specification.

4. The injection device of a two-stage venting injection molding machine for preventing material overflow according to claim 1, characterized in that: A discharge port is provided below the guide cover, and a cooling water channel is provided on the cooling connecting shaft.

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