Injection molding method for in-mold forming and injection molding equipment thereof

Abstract

The injection molding method comprises the following steps: (1) placing a functional membrane into a first cavity of the injection molding equipment, and injecting a first thermoplastic material to form a matrix layer; (2) the mold is opened, and the base body layer is rotated to the second cavity through rotation of the rotating mold; (3) injecting a second thermoplastic material into the second cavity to form a protective structure layer; (4) after injection is completed, the injection molding equipment executes mold opening and rotary mold rotating actions and mold closing, a functional membrane is placed in the first cavity, a first thermoplastic material is injected to form a base body layer, meanwhile, a thermosetting material is injected to the surface of the formed base body layer in the second cavity, and a second thermoplastic material is injected to the surface of the base body layer; synchronously curing the injected thermosetting material and the first thermoplastic material in the same molding period; and (5) opening the injection molding equipment to eject the product in the second cavity, and repeating the steps (2)-(5). According to the invention, multi-layer composite molding of the material can be realized in the mold, the production and processing steps are simplified, and the product quality is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, and in particular to an in-mold injection molding method and injection molding equipment. Background Technology

[0002] Currently, the common manufacturing process in the automotive lighting industry is "injection molding + subsequent painting." While this method is widely used, it also has several limitations, including high cost and high energy consumption. Because it requires separate production areas for multiple processes such as injection molding and painting, it not only occupies a significant amount of factory space but also increases equipment investment and maintenance costs. Furthermore, the multi-process manufacturing process not only consumes a lot of energy but also generates substantial carbon emissions, especially in the painting stage, where the emission of volatile organic compounds poses a risk of environmental pollution, failing to meet the requirements of modern environmentally friendly production.

[0003] Secondly, in the current automotive lighting production process, the product is typically manufactured through two different processing steps: first, injection molding, and then a secondary painting process. This traditional process is not only cumbersome and time-consuming, but also results in high defect rates, increasing production costs and time losses during process transitions. Therefore, how to combine thermoplastic and thermosetting materials in a single production process to simplify manufacturing has always been a pressing issue for the industry. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an in-mold injection molding method and injection molding equipment to solve the technical problems in the prior art, such as the inability to simultaneously complete the integrated molding of multiple thermoplastic and thermosetting materials in a single production process.

[0005] To achieve the above objectives, one aspect of the present invention provides an in-mold injection molding method, comprising the following steps: (1) Place a functional film into the first cavity of the injection molding equipment and inject a first thermoplastic material to form a matrix layer; (2) Open the mold and rotate the base layer into the second cavity by rotating the rotary mold; (3) Injecting a second thermoplastic material into the second cavity to form a protective structural layer; (4) After injection, the injection molding equipment performs mold opening and rotating mold operation and closes the mold, places the functional film into the first cavity and injects the first thermoplastic material to form the base layer, and injects thermosetting material into the surface of the already formed base layer in the second cavity, so that the injected thermosetting material and the first thermoplastic material are cured synchronously in the same molding cycle. (5) The injection molding equipment is opened to eject the product from the second cavity, and steps (2)-(5) are repeated.

[0006] Based on the above embodiments, the injection molding equipment includes a mold system, which includes a fixed mold, a rotary mold, and a moving mold. The rotary mold is located between the moving mold and the fixed mold. The moving mold and the rotary mold are used to form a first cavity, and the fixed mold and the rotary mold are used to form a second cavity.

[0007] Based on the above embodiments, the injection molding equipment includes an injection system, which includes multiple injection units for injecting different types of materials.

[0008] Based on the above embodiments, the injection molding equipment further includes an automated gripper, which is used to grip the functional mold piece into the first cavity and remove the finished product.

[0009] Based on the above embodiments, the functional template is used to bond with injected thermoplastic or thermosetting materials within the mold.

[0010] Based on the above embodiments, in step (2), the "molding" process includes the base layer being cooled and shaped within the first cavity.

[0011] Based on the above embodiments, in step (2), the rotation angle of the rotating mold is 180°.

[0012] Based on the above embodiments, in step (4), before the "mold opening", a protective structural layer is cooled and shaped in the second cavity.

[0013] Based on the above embodiments, in step (5), before the "injection molding equipment is opened", the first thermoplastic material and thermosetting material are cooled and shaped.

[0014] Based on the above embodiments, the rotating mold rotates by an angle of 180° and returns to its initial position.

[0015] Based on the above embodiments, in step (1), the first thermoplastic material and the second thermoplastic material are polycarbonate and polymethyl methacrylate materials.

[0016] Based on the above embodiments, in step (6), the thermosetting material is a polyurethane system material.

[0017] Another aspect of the present invention provides a one-step in-mold injection molding apparatus that applies the above-described in-mold injection molding method, comprising: The injection molding system includes multiple injection units for injecting different types of materials on the same injection molding equipment. A mold system for realizing multi-station injection molding of multiple cavity surfaces; The control system includes a central control module, an action switching module, and a parameter setting module. The control system is used to control the injection molding process of the mold system and the injection molding system.

[0018] Based on the above embodiments, the central control module is used to coordinate the action sequence of the injection unit and the mold system, so that thermoplastic materials and thermosetting materials are injected and molded sequentially in the same molding cycle.

[0019] Based on the above embodiments, the action switching module is used to control the action of the mold system to achieve position switching.

[0020] Based on the above embodiments, the parameter setting module is used to set the temperature, pressure, and time parameters for thermoplastic materials and thermosetting materials, respectively.

[0021] Compared with existing technologies, this invention has beneficial effects. This invention achieves the coordinated injection and synchronous curing of multiple injection molding materials within the same production cycle, and utilizes the rotating mold of the injection molding machine to enable multi-station coordinated production without significant structural changes. This invention breaks the inherent limitation of traditional injection molding equipment's "single mold, single cycle," achieving bidirectional expansion in both the time and spatial domains, and realizing parallelization of production cycle time and multiplication of molding efficiency at the process level. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of an in-mold injection molding method according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of an in-mold injection molding equipment according to an embodiment of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0027] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or end that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or ends.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] One aspect of the present invention provides an in-mold injection molding method, comprising the following steps: (1) Place a functional film into the first cavity of the injection molding equipment and inject a first thermoplastic material to form a matrix layer; (2) Open the mold and rotate the base layer into the second cavity by rotating the rotary mold; (3) Injecting a second thermoplastic material into the second cavity to form a protective structural layer; (4) After injection, the injection molding equipment performs mold opening and rotating mold operation and closes the mold, places the functional film into the first cavity and injects the first thermoplastic material to form the base layer, and injects thermosetting material into the surface of the already formed base layer in the second cavity, so that the injected thermosetting material and the first thermoplastic material are cured synchronously in the same molding cycle. (5) The injection molding equipment is opened to eject the product from the second cavity, and steps (2)-(5) are repeated.

[0031] Furthermore, the injection molding equipment includes a mold system, which includes a fixed mold, a rotary mold, and a moving mold. The moving mold and the rotary mold are combined to form a first cavity, and the fixed mold and the rotary mold are combined to form a second cavity.

[0032] Furthermore, the injection molding equipment also includes an automated gripper, which is used to grip the functional mold piece into the first cavity and remove the finished product.

[0033] This method achieves continuous production—from in-mold diaphragm embedding to two-component thermoplastic material injection molding to external protective structural layer spraying—through precise control of functional diaphragm embedding, dual-cavity synergistic injection, and rotary mold rotation switching. This ensures precise coordination of each process step, guarantees product quality stability and production efficiency, and changes the traditional segmented manufacturing model. By controlling the differentiated cavities of the mold, two thermoplastic materials (e.g., PC, PMMA, PC / ABS, PA, PBT) and one thermosetting material (e.g., polyurethane, polyurea) can be molded together on a single machine within a single cycle.

[0034] Example 1: The injection molding equipment consists of a fixed mold, a moving mold, and a rotary mold positioned between them. The rotary mold can rotate from 0° to 180° and back to 0°. The rotary mold and the moving mold close together to form a first cavity, and the rotary mold and the fixed mold close together to form a second cavity. In this example, the injection molding equipment includes three independent injection units, used for injecting a first thermoplastic material, a second thermoplastic material, and a thermosetting material, respectively.

[0035] At the beginning of production, both the first and second cavities of the injection molding equipment are open. An automated gripper picks up a functional diaphragm, which integrates patterning, optics, heating, and other functions, achieving product visual and functional integration.

[0036] The automated gripper uses vacuum adsorption to stably hold the functional diaphragm. After being gripped by the gripper, the functional diaphragm is quickly delivered into the area of ​​the first cavity. The functional diaphragm can be fixed by vacuum adsorption, electrostatic adsorption, or step limiting mechanism to ensure that the functional diaphragm is accurately positioned in the first cavity and one side is tightly attached to the surface of the rotating mold cavity, which facilitates direct contact and bonding with the injected thermoplastic material.

[0037] After the functional diaphragm is fixed, the injection molding equipment initiates the mold closing action. The moving mold moves towards the fixed mold, causing the rotating mold to close with the moving mold, thus compressing the first cavity and the second cavity to form a sealed space. After the mold closing is completed, the first injection unit begins to operate, and the first thermoplastic material (e.g., polycarbonate or polymethyl methacrylate) is injected onto the functional diaphragm in the first cavity. The first thermoplastic material flows within the cavity and adheres to the outer surface of the functional diaphragm to form a base layer.

[0038] After the first thermoplastic material has cooled, the injection molding equipment performs the mold opening action, the moving mold retracts, exposing the rotating mold and the substrate layer that has been formed in the first cavity. At this time, the substrate layer and the functional film are retained on the rotating mold as a whole. The injection molding equipment drives the rotating mold to rotate 180° around the central axis, so that the substrate layer originally located in the first cavity is moved to the position of the second cavity.

[0039] After the rotary mold reaches its position, the injection molding equipment performs the mold closing action. The second injection unit begins the injection operation. The second thermoplastic material can be a resin of the same or compatible system as the first thermoplastic material, such as polycarbonate (PC) or polymethyl methacrylate (PMMA). After the second thermoplastic material enters the second cavity, it bonds with the surface of the substrate layer to form a protective structural layer. After injection, the pressure holding and cooling stage begins, during which the temperature of the protective structural layer decreases and solidifies to form a complete double-layer structure.

[0040] After the protective structural layer is formed, the injection molding equipment performs a mold opening operation, the moving mold retracts to the set position, and the rotary mold prepares to rotate again. At this time, the product in the second cavity is a composite structure with a functional film, a substrate layer, and a protective structural layer. The injection molding equipment starts the rotary mold rotation action, and the formed double-layer product remains in the fixed mold position. After the rotary mold finishes rotating, the automated gripper sends the next functional film into the first cavity position, fixes it, and closes the mold.

[0041] At this time, the injection molding equipment performs two injection operations simultaneously: on the one hand, the first injection unit injects a first thermoplastic material into the first cavity to form a new matrix layer; on the other hand, the third injection unit injects a thermosetting material (e.g., a polyurethane system) into the surface of the functional membrane in the second cavity. The curing time of the thermosetting material is similar to the cooling time of the first thermoplastic material, allowing the two processes to be carried out synchronously within the same time period. While the first thermoplastic material is being injected and cured in the first cavity, the thermosetting material in the second cavity is also in the injection and curing stage.

[0042] After the thermosetting material and the base layer have cured, the injection molding equipment performs the mold opening action. The product is retained on the fixed mold and ejected to the part removal area. The automated gripper picks up the product and removes it from the mold area. At this point, the system automatically enters the next cycle, repeating the above steps to form a continuous automated production cycle.

[0043] The injection molding method of this invention is applicable to injection molding of the inner and outer surfaces of automotive lighting lamps, etc. Through the above steps, the method of this invention enables the continuous manufacturing of the base layer, protective structural layer, and thermosetting material layer within the same injection molding equipment, with all processes being fully automated without human intervention. Throughout the entire production cycle, the embedding of functional films, injection of thermoplastic materials, curing of thermosetting materials, and product ejection are repeated according to a predetermined program, achieving high-efficiency, low-defect production of multi-layer structural parts.

[0044] Another aspect of the present invention provides a one-step in-mold injection molding apparatus that applies the above-described in-mold injection molding method, comprising: An injection molding system comprises multiple injection units for injecting different types of materials on the same injection molding machine. The mold system is used to achieve multi-station injection molding with multiple cavity surfaces; The control system includes a central control module, an action switching module, and a parameter setting module. The control system is used to control the injection molding process of the mold system and the injection molding system.

[0045] Furthermore, the central control module is used to coordinate the action sequence of the injection unit and the mold system, so that thermoplastic materials and thermosetting materials are injected and molded sequentially in the same molding cycle.

[0046] Furthermore, the motion switching module is used to control the motion of the mold system to achieve position switching.

[0047] Furthermore, the parameter setting module is used to set the temperature, pressure, and time parameters for thermoplastic and thermosetting materials respectively.

[0048] Example 2: A one-step in-mold injection molding equipment, comprising an injection system, a mold system, and a control system. The injection system includes multiple injection units, each independently configured to inject different types of materials on the same injection machine. Each injection unit can independently set the temperature, pressure, and injection speed according to the characteristics of different materials, thereby achieving sequential injection and curing of multiple materials within the same molding cycle.

[0049] The mold system is used to achieve multi-station injection molding with multiple cavities. The mold system can complete its actions under the command of the control system, so that different injection stations correspond to different materials at different injection stages, thereby achieving multi-layer composite molding within the same mold structure.

[0050] The control system includes a central control module, an action switching module, and a parameter setting module. The control system is used to coordinate and control the injection molding process of the injection molding system and the mold system.

[0051] The central control module coordinates the operation sequence of the injection unit and the mold system, enabling thermoplastic and thermosetting materials to be injected and cured sequentially within the same molding cycle. The action switching module controls the station switching actions of the mold system, ensuring accurate and synchronized cavity position transitions. The parameter setting module allows for setting process parameters such as temperature, pressure, and time for both thermoplastic and thermosetting materials, ensuring optimal process conditions for different materials during both injection and curing stages.

[0052] With the above structural configuration, the one-step in-mold injection molding equipment of the present invention can realize the continuous injection and synchronous molding of multiple materials on the same equipment, simplifying the production process and improving molding efficiency and product quality.

[0053] This invention achieves one-step multi-material molding, revolutionizing the traditional secondary processing model. Relying on structural innovation and process optimization of through-shot injection molding equipment, it can simultaneously complete the integrated molding of two-color thermoplastic and thermosetting materials in a single production process, completely eliminating the redundant step of "secondary painting after injection molding" in traditional automotive lighting manufacturing. From a production efficiency perspective, the technical solution of this invention significantly shortens the product manufacturing cycle and reduces time and cost losses in process transitions. From an environmental and energy consumption perspective, eliminating the painting step not only avoids the use and emission of chemical solvents during painting but also reduces the additional energy consumption caused by multi-processing, significantly reducing carbon emissions and achieving green and efficient production. Secondly, the use of polyurethane materials for in-mold coating has multiple core advantages compared to traditional coating technologies.

[0054] Performance Dimensions: Polyurethane (PUR) coatings possess unique self-healing capabilities, allowing minor scratches to be repaired during long-term use, maintaining a bright and new appearance. They also exhibit excellent chemical corrosion resistance and aging resistance, effectively resisting the erosion of external chemicals, ultraviolet rays, and other factors, extending product lifespan. Furthermore, PUR materials allow for flexible adjustment of surface hardness to adapt to different application scenarios, and support diverse aesthetic effects such as high light transmittance, multi-color customization, and metallic finishes. They can also precisely replicate the microstructure texture of mold surfaces, providing greater freedom for the design and functional innovation of automotive lighting, significantly enhancing the product's premium feel and differentiated competitiveness. Environmental Dimensions: PUR material itself contains no chemical solvents and emits no volatile harmful gases during production and use, reducing environmental pollution at the source. This protective structural layer simultaneously achieves scratch resistance and stain resistance, effectively resisting ultraviolet radiation, rain erosion, and chemical corrosion, significantly slowing down the aging rate of the lampshade. It replaces the traditional UV paint spraying process after injection molding, further simplifying the process and reducing energy consumption and environmental pressure. This invention realizes a continuous production process of "in-mold functional membrane embedding—two-component thermoplastic material injection molding—out-of-mold protective structural layer spraying," ensuring precise coordination of each process link, guaranteeing product quality stability and production efficiency, and completely changing the traditional segmented manufacturing mode.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-mold injection molding method, characterized in that, Includes the following steps: (1) Place a functional film into the first cavity of the injection molding equipment and inject a first thermoplastic material to form a matrix layer; (2) Open the mold and rotate the base layer into the second cavity by rotating the rotary mold; (3) Injecting a second thermoplastic material into the second cavity to form a protective structural layer; (4) After injection, the injection molding equipment performs mold opening and rotating mold operation and closes the mold, places the functional film into the first cavity and injects the first thermoplastic material to form the base layer, and injects thermosetting material into the surface of the already formed protective structure layer in the second cavity, so that the injected thermosetting material and the first thermoplastic material are cured synchronously in the same molding cycle. (5) The injection molding equipment is opened to eject the product from the second cavity, and steps (2)-(5) are repeated.

2. The injection molding method according to claim 1, characterized in that, The injection molding equipment includes a mold system, which includes a fixed mold, a rotary mold, and a moving mold. The rotary mold is disposed between the moving mold and the fixed mold. The moving mold and the rotary mold are used to form a first cavity when they are closed, and the fixed mold and the rotary mold are used to form a second cavity.

3. The injection molding method according to claim 2, characterized in that, The injection molding equipment includes an injection system, which includes multiple injection units, each used to inject different types of materials.

4. The injection molding method according to claim 3, characterized in that, The injection molding equipment also includes an automated gripper, which is used to grip the functional film into the first cavity and remove the finished product.

5. The injection molding method according to claim 4, characterized in that, The functional membrane is used to bond with injected thermoplastic or thermosetting materials within the mold.

6. The injection molding method according to claim 1, characterized in that, In step (2), the "molding" process includes the base layer being cooled and shaped within the first cavity.

7. The injection molding method according to claim 6, characterized in that, In step (2), the rotating mold rotates by an angle of 180°.

8. The injection molding method according to claim 1, characterized in that, In step (4), the "molding" process includes a protective structural layer that is cooled and shaped within the second cavity.

9. The injection molding method according to claim 8, characterized in that, In step (4), the rotating mold rotates by 180° and returns to its initial position.

10. The injection molding method according to claim 1, characterized in that, In step (5), before the "injection molding equipment is opened", the first thermoplastic material and thermosetting material are cooled and shaped.

11. The injection molding method according to claim 1, characterized in that, In step (1), the first thermoplastic material and the second thermoplastic material are polycarbonate and polymethyl methacrylate materials.

12. The injection molding method according to claim 1, characterized in that, In step (6), the thermosetting material is a polyurethane system material.

13. A one-step in-mold injection molding equipment, characterized in that, The injection molding method using in-mold molding according to any one of claims 1-12 includes: The injection molding system includes multiple injection units for injecting different types of materials on the same injection molding equipment. A mold system for realizing multi-station injection molding of multiple cavity surfaces; The control system includes a central control module, an action switching module, and a parameter setting module. The control system is used to control the injection molding process of the mold system and the injection molding system.

14. The injection molding equipment according to claim 13, characterized in that, The central control module is used to coordinate the action sequence of the injection unit and the mold system, so that thermoplastic materials and thermosetting materials are injected and molded sequentially in the same molding cycle.

15. The injection molding equipment according to claim 14, characterized in that, The action switching module is used to control the actions of the mold system to achieve position switching.

16. The injection molding equipment according to claim 15, characterized in that, The parameter setting module is used to set the temperature, pressure, and time parameters for thermoplastic and thermosetting materials, respectively.

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