Multi-material co-injection injection molding machine and time sequence cooperative injection control method thereof

Abstract

The invention discloses a multi-material co-injection injection molding machine and a time sequence cooperative injection control method thereof, and particularly relates to the technical field of injection molding.The multi-material co-injection injection molding machine comprises an injection molding machine main body, an outer screw rod main body, an inner screw rod main body and a double-screw-rod switching mechanism; the injection molding machine main body comprises a movable mold plate, a fixed mold plate, a double-screw conveying heating pipe, a parallel double-tank main body, a double-screw rod switching mechanism and a double-screw rod pusher, the side edge of the movable mold plate is in contact with the fixed mold plate in an attached manner, and one side of the fixed mold plate is connected with the double-screw conveying heating pipe in an inserted manner; a parallel double-tank main body is placed above the two sides of the tail end of the double-screw conveying heating pipe, the driving end of the double-screw conveying heating pipe is fixedly connected with a double-screw rod switching mechanism, and the side edge of the double-screw rod switching mechanism is connected with a double-screw rod pushing machine. According to the structure, the length of the double-material runner is reduced to be the shortest, so that the time sequence error of melt reaching a mold cavity caused by runner difference is fundamentally eliminated.

Description

Technical Field

[0001] This application relates to the field of injection molding technology, and more specifically, to an injection molding machine for multi-material co-injection and a method for controlling the timing of co-injection. Background Technology

[0002] Multi-material co-injection molding is a core technology for realizing the one-piece molding of composite products made of dissimilar materials. It is widely used in automotive interior parts, consumer electronics housings, medical device seals, home appliance functional parts and other fields. It can simultaneously achieve composite functions such as structural strength and soft touch on a single product, replacing the traditional secondary injection molding and bonding assembly production methods, and improving production efficiency and product reliability. Existing patent CN109939894B discloses a multi-color injection molding machine, including an extrusion box and a fixed cavity disposed within the extrusion box. The fixed cavity is equipped with a fixing device, which includes top pressure blocks disposed within the fixed cavity. Multi-colored rubber tubes are placed between the top pressure blocks. The fixed cavity is equipped with symmetrically arranged extrusion devices, each with positioning teeth. The aim is to design an injection molding machine that is portable and easy to operate. This device can also fill different colored gels by filling the rubber tubes containing the gel. In the process of developing this application, the inventors discovered the following problems with the prior art: Existing multi-material injection molding machines generally adopt a multi-injection table separate layout structure, with multiple injection units installed side by side, opposite to each other or at an angle. The material flow channels have long convergence distances and asymmetrical flow paths. Even with synchronized commands via software, there are still errors in the timing of the melt reaching the mold cavity gate. The mold cavity pressure fluctuates greatly during injection switching, making it very easy to cause molding defects such as core layer penetration through the surface layer, interface delamination, and weld lines. Meanwhile, existing coaxial nested twin-screw injection molding structures generally use dual servo motors to independently drive the inner and outer screws, which cannot achieve mechanical hard locking of the non-working screws. They rely solely on motor brakes to achieve soft locking. During high-pressure injection, circumferential slippage and axial movement are prone to occur, resulting in material flow and poor layer thickness control accuracy, which cannot meet the molding requirements of high-precision composite products. Therefore, in order to address the above problems, a multi-material co-injection injection machine and its timing-coordinated injection control method are proposed. Summary of the Invention

[0003] In order to overcome the above-mentioned defects of the prior art, this application provides a multi-material co-injection injection machine and a timing-coordinated injection control method thereof to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this application provides the following technical solution: a multi-material co-injection injection molding machine, comprising an injection molding machine body, an outer spiral rod body, an inner spiral rod body, and a double spiral rod switching mechanism. The injection molding machine body includes a moving platen, a fixed platen, a double spiral conveying heating pipe, a parallel double tank body, a double spiral rod switching mechanism, and a double spiral rod pusher. The side of the moving platen is in contact with the fixed platen. A double spiral conveying heating pipe is inserted and connected to one side of the fixed platen. The parallel double tank body is placed above both sides of the end of the double spiral conveying heating pipe. The driving end of the double spiral conveying heating pipe is fixedly connected to the double spiral rod switching mechanism. A double spiral rod pusher is connected to the side of the double spiral rod switching mechanism. The double spiral rod switching mechanism includes a rotation switching component. The double-helix conveying heating tube includes an outer helical rod body and an inner helical rod body. The center of the outer helical rod body is hollow, and the inner helical rod body is inserted into the hollow of the outer helical rod body. The front ends of the outer helical rod body and the inner helical rod body share the same coaxial nozzle.

[0005] Preferably, the double-helix conveying heating tube further includes a heating tube body and an inner feeding docking box. The outer diameter surface of the outer helical rod body is fitted with the heating tube body. The feeding ends of the outer helical rod body and the inner helical rod body are connected to the feeding docking box. The inner feeding docking box is provided with independent outer screw feeding chamber and inner screw feeding chamber, which are respectively connected to the melting chamber of the outer helical rod body and the inner helical rod body.

[0006] Preferably, the double helix switching mechanism includes a rotation switching component, a docking plate, and a drive motor. The drive end of the rotation switching component has a docking plate, and the docking plate is located above the rotation switching component and is fixedly connected to the drive motor by bolts. The drive motor provides the sole rotational power for the entire system.

[0007] Preferably, the rotation switching assembly includes a switching contact assembly, a switching trigger assembly, and a drive shaft. One side of the switching contact assembly is engaged with the switching trigger assembly, and the drive end of the switching trigger assembly is connected to the drive shaft.

[0008] Preferably, the switching contact assembly includes an outer helical spline, a first sliding sleeve, an intermediate gear body, and an inner helical spline. The first sliding sleeve is placed at one end of the outer helical spline, and the inner helical spline is fixedly connected to the end of the first sliding sleeve away from the outer helical spline. The intermediate gear body is fixedly connected to the outer diameter surface of the first sliding sleeve. The outer helical spline is coaxially slidably connected to the tail of the outer helical spline body, and the inner helical spline is coaxially corresponding to the tail of the inner helical spline body.

[0009] Preferably, the inner helical rod body is connected to the first spline through the inner cavity of the inner helical rod spline, and the inner helical rod body and the first spline are slidably connected. The first spline can transmit circumferential rotational torque, while allowing the inner helical rod body to slide freely along the axial direction.

[0010] Preferably, the switching trigger assembly includes a solenoid valve, a connecting frame, an intermediate drive gear, an outer drive gear, an inner drive gear, a second sliding sleeve, and a second spline. The push end of the solenoid valve is fixedly connected to two sets of connecting frames, and the two sets of connecting frames are connected to the second sliding sleeve. An intermediate drive gear is provided on the outer diameter surface of the second sliding sleeve. An outer drive gear and an inner drive gear are respectively placed on both sides of the intermediate drive gear. The outer drive gear, the inner drive gear, and the second sliding sleeve are fixedly connected. The drive shaft is located in the inner cavity of the second sliding sleeve and is provided with a second spline. When the solenoid valve is driven, the solenoid valve drives the second sliding sleeve to move horizontally along the second spline of the drive shaft, and drives the outer drive gear, the inner drive gear, and the intermediate drive gear to reciprocate. Simultaneously, it drives the outer drive gear, the inner drive gear, and the intermediate drive gear to move axially, thereby realizing the switching of working conditions.

[0011] Preferably, a push docking frame is fixedly connected to the outer diameter surface of both the outer and inner helical rod bodies. A helical rod body push shaft is connected through the side of the push docking frame. The helical rod body push shaft is electrically connected to the double helical rod pusher. The double helical rod pusher includes two independent servo drive units, which drive the outer and inner helical rod bodies axially forward and backward, respectively.

[0012] Preferably, the two sides of the inner feeding docking box are respectively connected to the outer screw feeding chamber and the inner screw feeding chamber. The outer screw feeding chamber and the inner screw feeding chamber are respectively connected to the two storage tanks of the parallel double tank body. The bottom ends of the outer screw feeding chamber and the inner screw feeding chamber are fixedly connected to the limit bracket. A controller is bolted to the side of the injection molding machine body. The controller is electrically connected to the drive motor, solenoid valve, double helix pusher, heating tube body, and mold cavity sensor. A release back plate is provided on the side of the moving plate. An ejector pin is connected through the plate of the release back plate. A pusher frame is fixedly connected between the release back plate and the moving plate. The drive end of the pusher frame is connected to the mold closing cylinder of the injection molding machine body.

[0013] The technical effects and advantages of this application are as follows: Compared with existing technologies, this multi-material co-injection injection molding machine and its timing-coordinated injection control method adopt a coaxial nested structure of the outer and inner helical rod bodies, with both sharing the same coaxial nozzle at their front ends, allowing the surface material and core material to converge at the nozzle outlet. Compared with the existing multi-stage discrete layout with long flow channel convergence distances and asymmetrical flow paths, this structure compresses the length of the dual material flow channels to the shortest possible, fundamentally eliminating the timing error of melt arrival in the mold cavity caused by flow channel differences. At the same time, the drive motor, as the only rotational power source of the entire system, distributes power to the outer or inner helical rod as needed through the dual helical rod switching mechanism, avoiding the problem of asynchronous speed caused by motor response differences and encoder feedback delays when the dual servo motors are driven independently. In the timing-coordinated injection control method, the controller drives the second sliding sleeve to move linearly through a solenoid valve, and synchronously adjusts the linear increase and decrease of the propulsion speed of the dual helical rod pusher during the switching process, ensuring that the total flow rate and total pressure fluctuation value of the melt in the mold cavity are always controlled within the preset safety threshold.

[0014] Compared with existing technologies, this multi-material co-injection injection molding machine and its timing-coordinated injection control method, in this application, the double helix switching mechanism drives the second sliding sleeve to move horizontally along the second spline through the solenoid valve in the switching trigger assembly, which drives the outer drive gear, intermediate drive gear and inner drive gear to move axially synchronously, realizing the rapid switching of three working conditions: independent rotation of the outer helix, independent rotation of the inner helix, and synchronous rotation of the double helix. When a certain helix is ​​in a non-working state, its corresponding drive gear and spline are completely disengaged and a reserved anti-rotation space is reserved to form a mechanical hard lock, ensuring the absolute stationary position of the non-working screw and preventing material flow. The switching trigger assembly uses a three-position five-way solenoid valve to drive the second sliding sleeve to move linearly and smoothly. During the working condition switching process, the disengagement of the outer drive gear from the outer helix spline and the engagement of the inner drive gear with the inner helix spline are carried out gradually and continuously, and the power transmission is uninterrupted. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 This is a top view of the main body of the injection molding machine of this application; Figure 3 This is a schematic diagram of the left cross-sectional structure of the main body of the injection molding machine of this application; Figure 4 This is a structural schematic diagram of the main body of the parallel dual tanks in this application; Figure 5 This is a schematic diagram of the rotation switching component of this application; Figure 6 This is a schematic diagram of the switching trigger component of this application; Figure 7 This is a schematic diagram of the structure of the drive docking frame in this application; Figure 8 This is a schematic diagram of the structure of the solenoid valve of this application; Figure 9 This is a schematic diagram of the structure of the main body of the external helical rod in this application; Figure 10 This is a cross-sectional view of the double-helix conveying heating tube of this application.

[0016] The attached figures are labeled as follows: 1. Injection molding machine body; 2. Controller; 3. Detachable backplate; 4. Ejector pin; 5. Pusher frame; 6. Moving mold plate; 7. Fixed mold plate; 8. Twin-helix conveyor heating tube; 9. Parallel dual-tank body; 10. Twin-helix switching mechanism; 11. Twin-helix pusher; 12. Outer screw feed chamber; 13. Inner screw feed chamber; 14. Limit bracket; 15. Rotation switching assembly; 16. Connecting plate; 17. Drive motor; 18. Heating tube body; 19. Outer helix body; 20. 21. Inner helical rod body; 22. Feed docking box; 23. Switching contact component; 24. Switching trigger component; 25. Drive shaft; 26. Outer helical rod spline; 27. First sliding sleeve; 28. Intermediate gear body; 29. ​​Inner helical rod spline; 30. First spline; 31. Push docking frame; 32. Helical rod body push shaft; 33. Solenoid valve; 34. Connecting frame; 35. Intermediate drive gear; 36. Outer drive gear; 37. Inner drive gear; 38. Second sliding sleeve; 39. Second spline. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Example 1 As attached Figures 1 to 10The injection molding machine shown includes a multi-material co-injection system, comprising a machine body 1, an outer helical rod body 19, an inner helical rod body 20, and a double helical rod switching mechanism 10. The machine body 1 includes a moving mold plate 6, a fixed mold plate 7, a double helical conveyor heating pipe 8, a parallel dual-tank body 9, the double helical rod switching mechanism 10, and a double helical rod pusher 11. The side of the moving mold plate 6 is in contact with the fixed mold plate 7. After the moving mold plate 6 and the fixed mold plate 7 are closed, a closed mold cavity is formed, providing a cavity for product molding. A double helical conveyor heating pipe is inserted and connected to one side of the fixed mold plate 7. The injection nozzle of the heat pipe 8 and the fixed mold plate 7 are coaxially connected. The upper sides of the ends of the heat pipe 8 are equipped with parallel double tank bodies 9. The two storage tanks of the parallel double tank bodies 9 store the surface material and the core material respectively, which can realize the drying and constant temperature conveying of the material. The drive end of the heat pipe 8 is fixedly connected to the double helix rod switching mechanism 10. The side of the double helix rod switching mechanism 10 is connected to the double helix rod pusher 11. The double helix rod switching mechanism 10 includes a rotation switching component 15. The double-helix conveying heating tube 8 includes an outer helical rod body 19 and an inner helical rod body 20. The center of the outer helical rod body 19 is hollow, and the inner helical rod body 20 is inserted into the hollow of the outer helical rod body 19. The front ends of the outer helical rod body 19 and the inner helical rod body 20 share the same coaxial nozzle, so that the two materials can converge at the nozzle outlet, the flow channel length is minimized, and there are no dead corners.

[0019] When performing multi-material injection molding on an injection molding machine, materials are injected into the outer screw feed chamber 12 and the inner screw feed chamber 13 through the parallel dual-tank body 9. The materials enter the conveying chambers of the outer screw body 19 and the inner screw body 20 respectively through connected channels. At this time, the materials are driven and conveyed by the corresponding screws within the cavities of the outer screw body 19 and the inner screw body 20. The materials are heated by the heating tube body 18, causing the cavities of the outer screw body 19 and the inner screw body 20 to simultaneously melt two types of injected materials. Then, the dual screw switching mechanism 10 is driven and operated by the drive motor 17, and the drive shaft 24 in the switching trigger component 23 of the driven rotation switching assembly 15 rotates. The intermediate drive gear 34, the outer drive gear 35, and the inner drive gear 36 rotate. Because the intermediate drive gear 34 meshes with the intermediate gear body 27, it drives the intermediate gear body 27 on the first sliding sleeve 26, which is connected to the outer helical rod body 19 and the inner helical rod body 20, to rotate. At the same time, the rotation of the intermediate gear body 27 causes the outer helical rod body 19 and the inner helical rod body 20 to rotate. When double-end injection is performed, the helical rod body push shaft 31 on the double helical rod pusher 11 drives the push docking frame 30 on the outer helical rod body 19 and the inner helical rod body 20 to move. This causes the outer helical rod body 19 and the inner helical rod body 20, which are connected to the push docking frame 30, to move forward simultaneously, thereby injecting the melt in the two chambers into the mold. When the outer spiral rod body 19 needs to transport the molten liquid while the inner spiral rod body 20 does not, the solenoid valve 32 switches and drives the second sliding sleeve 37 to move. At this time, the outer drive gear 35 on the second sliding sleeve 37 gradually meshes with the outer spiral rod spline 25, while the inner drive gear 36 is between the intermediate gear and the inner drive gear 36. At this time, the outer spiral rod body 19 rotates and is pushed to inject the molten liquid into the mold. Then the solenoid valve 32 resets and pushes towards the inner spiral rod spline 28, gradually meshing the inner drive gear 36 with the inner spiral rod spline 28, so that the inner spiral rod body 20 obtains rotational power, and is pushed by the other spiral rod body push shaft 31 of the double spiral rod pusher 11 to push and inject the molten liquid in the front end cavity of the inner spiral rod body 20, thereby realizing the injection of the front outer spiral tube and the injection of the rear inner spiral tube. If it is necessary to inject the molten liquid in the inner spiral rod body 20 before the outer spiral rod body 19, the solenoid valve 32 is first driven to connect the inner drive gear 36 with the inner spiral rod spline 28, and then reset so that the outer drive gear 35 connects with the outer spiral rod spline 25, thereby achieving the effect of the inner spiral rod body being injected first and the outer spiral rod body being injected later. Different injection effects can be achieved by switching. In addition, when the outer spiral rod body 19 or the inner spiral rod body 20 is rotated, the intermediate gear body 27 and the intermediate drive gear 34 are in a separated state.

[0020] Example 2.

[0021] Based on Example 1, the solution in Example 1 will be further described in detail below with reference to the specific working method, such as... Figures 1 to 10 As shown below, see details: In a preferred embodiment, the double-helix conveying heating tube 8 also includes a heating tube body 18 and an inner feed docking box 21. The outer diameter surface of the outer helical rod body 19 is fitted with the heating tube body 18. The heating tube body 18 can independently control the heating temperature of each section to adapt to the melting characteristics of the material. The feed ends of the outer helical rod body 19 and the inner helical rod body 20 are connected to the inner feed docking box 21. The inner feed docking box 21 is provided with independent outer screw feed chamber and inner screw feed chamber, which are respectively connected to the melting chambers of the outer helical rod body 19 and the inner helical rod body 20 to prevent the two materials from mixing during the feeding stage.

[0022] In a preferred embodiment, the double helix switching mechanism 10 includes a rotation switching assembly 15, a docking plate 16, and a drive motor 17. The drive end of the rotation switching assembly 15 is fitted with the docking plate 16, which is a steel plate box structure used to ensure that the drive motor 17 transmits power to the rotation switching assembly 15. The docking plate 16 is located above the rotation switching assembly 15 and is fixedly connected to the drive motor 17 by bolts. The drive motor 17 is a servo motor, which provides the only rotational power for the entire system, eliminating the need for dual servo drives.

[0023] In a preferred embodiment, the rotation switching assembly 15 includes a switching contact assembly 22, a switching trigger assembly 23, and a drive shaft 24. The switching contact assembly 22 is engaged with the switching trigger assembly 23 on one side, and the drive end of the switching trigger assembly 23 is connected to the drive shaft 24.

[0024] In a preferred embodiment, the switching contact assembly 22 includes an outer helical spline 25, a first sliding sleeve 26, an intermediate gear body 27, and an inner helical spline 28. The first sliding sleeve 26 is placed at one end of the outer helical spline 25, and the inner helical spline 28 is fixedly connected to the end of the first sliding sleeve 26 away from the outer helical spline 25. The intermediate gear body 27 is fixedly connected to the outer diameter surface of the first sliding sleeve 26. The outer helical spline 25 and the tail of the outer helical body 19 are coaxially slidably connected. When the outer helical body 19 is pushed by the double helical pusher 11 connected to the push docking frame 30, the outer helical body 19 and the outer helical spline 25 are connected by a spline, which realizes horizontal movement while keeping the outer helical body 19 in a rotating state. The inner helical spline 28 is coaxially corresponding to the tail of the inner helical body 20. The outer helical spline 25, the first sliding sleeve 26, and the inner helical spline 28 are arranged coaxially to ensure the coaxiality of the transmission.

[0025] In a preferred embodiment, the inner helical rod body 20 is located in the inner cavity of the inner helical rod spline 28 and is connected by a first spline 29. The inner helical rod body 20 and the first spline 29 are slidably connected. The first spline 29 can transmit circumferential rotational torque, while allowing the inner helical rod body 20 to slide freely along the axial direction, thereby decoupling the rotational transmission from the axial injection action.

[0026] In a preferred embodiment, the switching trigger assembly 23 includes a solenoid valve 32, a connecting bracket 33, an intermediate drive gear 34, an outer drive gear 35, an inner drive gear 36, a second sliding sleeve 37, and a second spline 38. The solenoid valve 32 is a three-position five-way solenoid valve. The cylinder of the solenoid valve 32 is fixed to the housing of the switching trigger assembly 23. Two sets of connecting brackets 33 are fixedly connected to the pushing end, and the ends of the two sets of connecting brackets 33 are fixedly connected to the second sliding sleeve 37. The outer diameter surface of the second sliding sleeve 37 is integrally formed with the inner drive gear 36, the intermediate drive gear 34, and the outer drive gear 35 from left to right. The drive shaft 24 is located in the inner cavity of the second sliding sleeve 37 and the second spline 38 is provided through it. The second sliding sleeve 37 meshes with the second spline 38 through the inner spline. When the solenoid valve 32 is driven, the solenoid valve 32 drives the second sliding sleeve 37 along the second spline 38 of the drive shaft 24. The key 38 moves horizontally and reciprocates, simultaneously driving the outer drive gear 35, inner drive gear 36, and intermediate drive gear 34 to move axially, thus achieving rapid switching between three working conditions. The push end of the solenoid valve 32 is fixedly connected to two sets of connecting brackets 33, and the two sets of connecting brackets 33 are connected to the second sliding sleeve 37. The outer diameter surface of the second sliding sleeve 37 is provided with the intermediate drive gear 34. The outer drive gear 35 and inner drive gear 36 are respectively placed on both sides of the intermediate drive gear 34. The outer drive gear 35, inner drive gear 36, and second sliding sleeve 37 are fixedly connected. The drive shaft 24 is located in the inner cavity of the second sliding sleeve 37 and is provided with the second spline 38. When the solenoid valve 32 is driven, the solenoid valve 32 drives the second sliding sleeve 37 to move horizontally along the second spline 38 of the drive shaft 24, and drives the outer drive gear 35, inner drive gear 36, and intermediate drive gear 34 to reciprocate.

[0027] In a preferred embodiment, a push docking frame 30 is fixedly connected to the outer diameter surface of both the outer helical rod body 19 and the inner helical rod body 20. A helical rod body push shaft 31 is connected through the side of the push docking frame 30. The helical rod body push shaft 31 is electrically connected to the double helical rod pusher 11. The double helical rod pusher 11 includes two independent servo drive units, which drive the outer helical rod body 19 and the inner helical rod body 20 to advance and retreat axially, respectively, so as to realize independent injection speed, pressure and stroke control of the two sets of screws.

[0028] In a preferred embodiment, the two sides of the inner feed docking box 21 are respectively connected to the outer screw feed chamber 12 and the inner screw feed chamber 13. The outer screw feed chamber 12 and the inner screw feed chamber 13 are respectively connected to the two storage tanks of the parallel double tank body 9. The bottom ends of the outer screw feed chamber 12 and the inner screw feed chamber 13 are fixedly connected to the limit bracket 14 to ensure the stability of the feeding structure. A controller 2 is bolted to the side of the injection molding machine body 1. The controller 2 is a PLC controller with a built-in timing collaborative control algorithm. The controller 2 is electrically connected to the drive motor 17, solenoid valve 32, double helix pusher 11, heating tube body 18, and mold cavity sensor. A release back plate 3 is provided on the side of the moving plate 6. An ejector pin 4 is connected through the plate of the release back plate 3. A pusher frame 5 is fixedly connected between the release back plate 3 and the moving plate 6. The drive end of the pusher frame 5 is connected to the mold closing cylinder of the injection molding machine body 1 to realize the mold opening, mold closing and ejection demolding actions.

[0029] The working process of this application is as follows: First, the controller 2 presets the timing coordination control parameters for the entire molding cycle based on the structural requirements of the product to be molded and the rheological characteristics of the surface material and the core material. These parameters include the working condition switching trigger threshold of the double helix switching mechanism 10, the injection speed and pressure curve of the double helix pusher 11, the holding pressure timing parameters, and the mold cavity melt state warning threshold. At the same time, the timing windows corresponding to the three basic working conditions of the double helix switching mechanism 10 are preset. Then, the controller 2 sends a command to the double helix switching mechanism 10, which drives the second sliding sleeve 37 to move horizontally along the second spline 38 of the drive shaft 24 to the intermediate position through the solenoid valve 32, so that the intermediate drive gear 34 meshes with the intermediate gear body 27. The drive motor 17 drives the outer helix spline 25 and the inner helix spline 28 to rotate synchronously, thereby driving the outer helix body 19 and the inner helix body 20 to rotate synchronously. At the same time, the controller 2 controls the double helix pusher 11, which drives the two sets of push docking frames 30 to retreat synchronously through the helix body push shaft 31, thereby establishing back pressure matching the corresponding material characteristics for the outer helix body 19 and the inner helix body 20 respectively. After the surface pre-injection timing closed-loop control pre-plasticization is completed, the controller 2 sends a command to the double helix switching mechanism 10, which drives the second sliding sleeve 37 to switch to the outer rotation and inner stop position through the solenoid valve 32, so that the outer drive gear 35 meshes with the outer helix spline 25, and the inner helix spline 28 and the inner drive gear 36 are reserved with anti-rotation space; the controller 2 controls the drive motor 17 to drive the outer helix body 19 to rotate, and at the same time controls the double helix pusher 11 to drive the outer helix body 19 to advance axially according to the preset speed curve, injecting the surface melt into the mold cavity formed by the fixed mold plate 7 and the moving mold plate 6; When the collected melt front reaches the preset switching trigger threshold, the controller 2 synchronously triggers a dual-path coordinated action: the first path controls the solenoid valve 32 to drive the second sliding sleeve 37 to move linearly and smoothly along the second spline 38, gradually disengaging the outer drive gear 35 from the outer helical spline 25 and gradually completing the engagement of the inner drive gear 36 with the inner helical spline 28; the second path controls the twin helical pusher 11 to synchronously adjust the linear decrease of the propulsion speed of the outer helical body 19 and the linear increase of the propulsion speed of the inner helical body 20; throughout the process, the total melt flow rate and total pressure fluctuation value in the mold cavity are kept within the preset safety threshold. After the smooth switching is completed, the second sliding sleeve 37 reaches the inner-to-outer stop position, the outer spiral spline 25 disengages from the outer drive gear 35, the controller 2 controls the drive motor 17 to drive the inner spiral body 20 to rotate, and at the same time controls the double spiral pusher 11 to drive the inner spiral body 20 to advance axially along the preset curve to complete the main filling of the core layer molten material; during the process, the controller 2 controls the outer spiral body 19 to maintain low pressure through the double spiral pusher 11, and monitors the pressure difference between the surface layer and the core layer interface in real time to prevent the core layer molten material from breaking through the surface layer; When the core layer melt fills to the preset sealing position threshold, the controller 2 synchronously triggers a reverse smooth switch: the control solenoid valve 32 drives the second sliding sleeve 37 to linearly retract to the outer turn inner stop position, and at the same time controls the double helical rod pusher 11 to synchronously adjust the pushing speed of the inner helical rod body 20 to decrease linearly and the pushing speed of the outer helical rod body 19 to increase linearly, maintaining constant mold cavity pressure throughout the process, and completing the seamless switch of surface sealing and filling; After the twin-screw synergistic pressure holding and timing dynamic compensation sealing and filling are completed, the controller 2 controls the twin-screw switching mechanism 10 to maintain the outer rotation and inner stop position. At the same time, according to the curing characteristics of the surface and core materials, the controller controls the twin-screw pusher 11 to output matching staged pressure holding pressure and pressure holding timing for the outer screw body 19 and the inner screw body 20 respectively. During the process, the pressure holding timing parameters are dynamically adjusted according to the real-time collected mold cavity temperature and pressure data to compensate for the molding deviation caused by material thermal shrinkage. After the cooling demolding and parameter iteration optimization holding pressure sequence are completed, the controller 2 controls the double helix switching mechanism 10 to lock the outer helix body 19 and the inner helix body 20. After the product cools to the preset demolding temperature, the controller controls the moving platen 6 to open the mold and ejects the product through the ejector pin 4. At the same time, the controller 2 synchronously iterates the melt state, molding parameters, and product quality data of this molding cycle to the parameter library and automatically optimizes the timing coordination control parameters of the next molding cycle. The above is the working principle of this multi-material co-injection injection molding machine and its timing coordination injection control method.

Claims

1. A multi-material co-injection injection molding machine, comprising an injection molding machine body (1), an outer helical rod body (19), an inner helical rod body (20), and a double helical rod switching mechanism (10), characterized in that: The injection molding machine body (1) includes a moving template (6), a fixed template (7), a double helix conveying heating tube (8), a parallel double tank body (9), a double helix switching mechanism (10), and a double helix pusher (11). The side of the moving template (6) is in contact with the fixed template (7). The side of the fixed template (7) is connected to the double helix conveying heating tube (8). The parallel double tank body (9) is placed above the two ends of the double helix conveying heating tube (8). The driving end of the double helix conveying heating tube (8) is fixedly connected to the double helix switching mechanism (10). The side of the double helix switching mechanism (10) is connected to the double helix pusher (11). The double helix switching mechanism (10) includes a rotation switching component (15). The double helix conveying heating tube (8) includes an outer helix rod body (19) and an inner helix rod body (20). The outer helix rod body (19) has a hollow center, and the inner helix rod body (20) is inserted into the hollow center of the outer helix rod body (19).

2. The injection molding machine for multi-material co-injection according to claim 1, characterized in that: The double helix conveying heating tube (8) also includes a heating tube body (18) and an inner feed docking box (21). The outer diameter surface of the outer helix rod body (19) is fitted with the heating tube body (18). The feed ends of the outer helix rod body (19) and the inner helix rod body (20) are connected to the inner feed docking box (21).

3. The injection molding machine for multi-material co-injection according to claim 1, characterized in that: The double helical switching mechanism (10) includes a rotation switching assembly (15), a docking plate (16) and a drive motor (17). The drive end of the rotation switching assembly (15) is equipped with the docking plate (16), and the docking plate (16) is located above the rotation switching assembly (15) and is fixedly connected to the drive motor (17) by bolts.

4. The injection molding machine for multi-material co-injection according to claim 1, characterized in that: The rotation switching assembly (15) includes a switching contact assembly (22), a switching trigger assembly (23) and a drive shaft (24). The switching contact assembly (22) is engaged with the switching trigger assembly (23) on one side, and the drive end of the switching trigger assembly (23) is connected to the drive shaft (24).

5. The injection molding machine for multi-material co-injection according to claim 4, characterized in that: The switching contact assembly (22) includes an outer helical spline (25), a first sliding sleeve (26), an intermediate gear body (27), and an inner helical spline (28). The first sliding sleeve (26) is placed at one end of the outer helical spline (25), and the inner helical spline (28) is fixedly connected to the end of the first sliding sleeve (26) away from the outer helical spline (25). The intermediate gear body (27) is fixedly connected to the outer diameter surface of the first sliding sleeve (26).

6. The injection molding machine for multi-material co-injection according to claim 1, characterized in that: The inner helical rod body (20) is located in the inner cavity of the inner helical rod spline (28) and is connected to the first spline (29). The inner helical rod body (20) and the first spline (29) are slidably connected.

7. The injection molding machine for multi-material co-injection according to claim 4, characterized in that: The switching trigger assembly (23) includes a solenoid valve (32), a connecting bracket (33), an intermediate drive gear (34), an outer drive gear (35), an inner drive gear (36), a second sliding sleeve (37), and a second spline (38). The push end of the solenoid valve (32) is fixedly connected to two sets of connecting brackets (33), and the two sets of connecting brackets (33) are connected to the second sliding sleeve (37). The outer diameter surface of the second sliding sleeve (37) is provided with an intermediate drive gear (34), and an outer drive gear is placed on both sides of the intermediate drive gear (34). The gear (35) and the inner drive gear (36) are fixedly connected to the outer drive gear (35), the inner drive gear (36) and the second sliding sleeve (37). The drive shaft (24) is located in the inner cavity of the second sliding sleeve (37) and is provided with a second spline (38). When the solenoid valve (32) is driven, the solenoid valve (32) drives the second sliding sleeve (37) to move horizontally along the second spline (38) of the drive shaft (24), and drives the outer drive gear (35), the inner drive gear (36) and the intermediate drive gear (34) to reciprocate.

8. The injection molding machine for multi-material co-injection according to claim 1, characterized in that: The outer diameter surfaces of the outer helical rod body (19) and the inner helical rod body (20) are fixedly connected to a push docking frame (30). The side of the push docking frame (30) is connected through a helical rod body push shaft (31). The helical rod body push shaft (31) is electrically connected to the double helical rod pusher (11).

9. The injection molding machine for multi-material co-injection according to claim 2, characterized in that: The inner feed docking box (21) is connected to the outer screw feed chamber (12) and the inner screw feed chamber (13) on both sides respectively. The bottom ends of the outer screw feed chamber (12) and the inner screw feed chamber (13) are fixedly connected to the limit bracket (14). The side of the injection molding machine body (1) is fixedly connected to a controller (2) by bolts. The side of the moving template (6) is provided with a detachment back plate (3). The plate of the detachment back plate (3) is connected through a ejector pin (4). A pusher frame (5) is fixedly connected between the detachment back plate (3) and the moving template (6).

10. A time-series coordinated injection control method for multi-material co-injection, characterized in that: The time-series coordinated injection control method includes the following steps: Step 1: First, the controller (2) presets the timing coordination control parameters for the entire molding cycle based on the structural requirements of the product to be molded and the rheological characteristics of the surface material and the core material. These parameters include the working condition switching trigger threshold of the double helix switching mechanism (10), the injection speed and pressure curve of the double helix pusher (11), the holding pressure timing parameters, and the mold cavity melt state warning threshold. At the same time, the timing windows corresponding to the three basic working conditions of the double helix switching mechanism (10) are preset. Step 2: Then the controller (2) sends a command to the double helical rod switching mechanism (10), and drives the second sliding sleeve (37) to move horizontally to the middle position along the second spline (38) of the drive shaft (24) through the solenoid valve (32), so that the middle drive gear (34) meshes with the middle gear body (27), and the drive motor (17) drives the outer helical rod spline (25) and the inner helical rod spline (28) to rotate synchronously, thereby driving the outer helical rod body (19) and the inner helical rod body (20) to rotate synchronously; at the same time, the controller (2) controls the double helical rod pusher (11), and drives the two sets of push docking frames (30) to retreat synchronously through the helical rod body push shaft (31), so as to establish back pressure matching the corresponding material characteristics for the outer helical rod body (19) and the inner helical rod body (20); Step 3: After the surface pre-injection timing closed-loop control pre-plasticization is completed, the controller (2) sends a command to the double helix switching mechanism (10), and drives the second sliding sleeve (37) to switch to the outer rotation and inner stop position through the solenoid valve (32), so that the outer drive gear (35) meshes with the outer helix spline (25), and the inner helix spline (28) and the inner drive gear (36) reserve anti-rotation space; the controller (2) controls the drive motor (17) to drive the outer helix body (19) to rotate, and at the same time controls the double helix pusher (11) to drive the outer helix body (19) to advance axially according to the preset speed curve, and inject the surface melt into the mold cavity formed by the fixed mold plate (7) and the moving mold plate (6); Step 4: When the collected melt front position reaches the preset switching trigger threshold, the controller (2) synchronously triggers dual-path coordinated action: First path, the solenoid valve (32) drives the second sliding sleeve (37) to move linearly and smoothly along the second spline (38), gradually disengaging the outer drive gear (35) from the outer spiral spline (25) and gradually completing the engagement of the inner drive gear (36) with the inner spiral spline (28); Second path, the double spiral pusher (11) synchronously adjusts the linear decrease of the propulsion speed of the outer spiral body (19) and the linear increase of the propulsion speed of the inner spiral body (20); throughout the process, the total melt flow rate and total pressure fluctuation value in the mold cavity are kept within the preset safety threshold. Step 5: After the smooth switching is completed, the second sliding sleeve (37) reaches the inner rotation and outer stop position, the outer spiral spline (25) disengages from the outer drive gear (35), the controller (2) controls the drive motor (17) to drive the inner spiral body (20) to rotate, and at the same time controls the double spiral pusher (11) to drive the inner spiral body (20) to advance axially according to the preset curve to complete the main filling of the core layer melt; during the process, the controller (2) controls the outer spiral body (19) to maintain low pressure through the double spiral pusher (11), and monitors the pressure difference between the surface layer and the core layer interface in real time to prevent the core layer melt from breaking through the surface layer; Step 6: When the core layer melt fills to the preset sealing position threshold, the controller (2) synchronously triggers the reverse smooth switching: the control solenoid valve (32) drives the second sliding sleeve (37) to linearly retract to the outer turn inner stop position, and at the same time controls the double helical rod pusher (11) to synchronously adjust the linear decrease of the inner helical rod body (20) and the linear increase of the outer helical rod body (19), keeping the mold cavity pressure constant throughout the process, and completing the seamless switching of surface sealing and filling; Step 7: After the twin-screw synergistic pressure holding and timing dynamic compensation sealing and filling are completed, the controller (2) controls the twin-screw switching mechanism (10) to maintain the outer rotation and inner stop position. At the same time, according to the curing characteristics of the surface and core materials, the controller controls the twin-screw pusher (11) to output matching staged pressure holding pressure and pressure holding timing for the outer screw body (19) and the inner screw body (20) respectively. During the process, the pressure holding timing parameters are dynamically adjusted according to the real-time collected mold cavity temperature and pressure data to compensate for the molding deviation caused by material thermal shrinkage. Step 8: Cooling, demolding and parameter iteration optimization. After the holding pressure sequence is completed, the controller (2) controls the double helix switching mechanism (10) to lock the outer helix body (19) and the inner helix body (20). After the product cools to the preset demolding temperature, the controller controls the moving template (6) to open the mold and ejects the product through the ejector pin (4). At the same time, the controller (2) synchronously iterates the melt state, molding parameters and product quality data of this molding cycle to the parameter library and automatically optimizes the timing coordination control parameters of the next molding cycle.

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