Process optimization method and system for pc and pmma co-extrusion composite back cover

Abstract

The present application relates to the field of plastic forming process, specifically to a PC and PMMA co-extrusion composite rear cover process optimization method and system, implement rear cover modeling analysis, determine the interface between PC melt and PMMA melt during co-extrusion pouring, so as to determine the motion attribute of PC melt and PMMA melt; according to the motion attribute and melt attribute, determine the flow difference of PC melt and PMMA melt, so as to predict the morphological difference of PC layer and PMMA layer after extrusion; numerical analysis is carried out on the morphological difference, the fluid dynamics anomaly of PC melt and PMMA melt during co-extrusion pouring is determined, and the melt driving strategy is generated; according to the melt driving strategy, the multi-conveying channel verification is carried out on PC melt and PMMA melt respectively, so as to determine the conveying channel configuration parameter. The present application determines the interface during PC and PMMA co-extrusion, so as to represent the flow difference and morphological difference of the two melts; the melt driving strategy and adaptive conveying channel configuration parameter are also generated, the co-extrusion process is optimized at the hardware and operation level, and the yield is improved.

Description

Technical Field

[0001] This invention relates to the field of plastic molding processes, and more particularly to a method and system for optimizing the process of co-extrusion composite back cover of PC and PMMA. Background Technology

[0002] As an important mobile phone accessory, the back cover plays a crucial role in protecting the internal electronic components and improving the phone's impact resistance. To reduce phone weight and improve the mechanical properties of the back cover, plastic materials such as polycarbonate (PC) and polymethyl methacrylate (PMMA) are preferred for its fabrication. However, considering the high hardness and toughness of PC and the high brittleness of PMMA, using only PC or PMMA to make the back cover cannot simultaneously meet the requirements for hardness, flexibility, and flexibility. Traditional technology co-extrudes PC melt and PMMA melt to form a composite material, thus overcoming the shortcomings of using a single material.

[0003] Co-extrusion involves heating PC and PMMA separately to form melts, then co-extruding these melts, delivered through different channels, into a back cover die using co-extrusion equipment. The resulting composite material fills the back cover die and exits. PC and PMMA have different melting temperatures and viscosities, resulting in different flow states for the PC and PMMA components in the co-extruded composite material. Synchronous flow of these two components cannot be guaranteed, leading to misalignment. Furthermore, the composite material expands after exiting the die. Due to the material differences between PC and PMMA, this expansion is inconsistent, exacerbating the misalignment defect, increasing the workload of back cover cutting / grinding, and compromising yield. Therefore, adapting to the hydrodynamic differences between PC and PMMA in their molten state and optimizing co-extrusion process parameters are crucial for improving the mechanical properties and yield of the back cover. Summary of the Invention

[0004] Considering the differences in hydrodynamics between PC and PMMA in the molten state, misalignment of different material layers and inconsistent extrusion expansion ratios may occur during co-extrusion, affecting the regularity of the shell shape and the yield rate.

[0005] To avoid this, the present invention provides an optimized process for co-extrusion composite back cover of PC and PMMA, the method comprising the following steps:

[0006] S100: Perform back cover modeling analysis to determine the interface between PC melt and PMMA melt during co-extrusion casting; determine the motion properties of PC melt and PMMA melt based on the interface;

[0007] S200: Based on the motion properties and melt properties, determine the flow difference between the PC melt and the PMMA melt, thereby predicting the morphological difference between the PC layer and the PMMA layer after extrusion;

[0008] S300: Perform numerical analysis on the morphological differences to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; generate a melt driving strategy based on the hydrodynamic anomalies.

[0009] S400: According to the melt driving strategy, perform multi-delivery channel verification on the PC melt and the PMMA melt respectively to determine the delivery channel configuration parameters.

[0010] Preferably, in S100, a back cover modeling analysis is performed to determine the interface between the PC melt and the PMMA melt during co-extrusion casting; based on the interface, the motion properties of the PC melt and the PMMA melt are determined, specifically:

[0011] The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained, and the three-dimensional structural data are subjected to mesh finite element modeling analysis to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold; wherein, the co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt.

[0012] Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the co-extrusion casting process in the back cover mold.

[0013] Using the interface as a reference, the multimodal motion parameters of the PC melt and the PMMA melt inside the rear cover mold are compared to determine the relative motion deviation between the PC melt and the PMMA melt; wherein, the multimodal motion parameters include motion direction and motion speed.

[0014] Preferably, in S200, the flow difference between the PC melt and the PMMA melt is determined based on the kinematic properties and melt properties, thereby predicting the morphological difference between the extruded PC layer and the PMMA layer, specifically as follows:

[0015] Based on the melt viscosity of the PC melt and the PMMA melt and the relative motion deviation attribute, the flow velocity gradient distribution of the PC melt and the PMMA melt in the three-dimensional space is obtained; by comparing the flow velocity gradient distribution of the PC melt and the PMMA melt, the difference in flow velocity gradient distribution between the PC melt and the PMMA melt is obtained.

[0016] The difference in flow velocity gradient distribution is converted by time integration to predict the position of the outer peripheral surface of the PC melt and the PMMA melt respectively; the outer peripheral surface positions of the PC melt and the PMMA melt are compared to determine the shape difference of the PC layer and PMMA layer formed after extrusion of the PC melt and PMMA melt; wherein, the shape difference includes the dimensional offset of the PC layer and PMMA layer due to extrusion expansion.

[0017] Preferably, in S300, the morphological differences are numerically analyzed to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; based on the hydrodynamic anomalies, a melt driving strategy is generated, specifically as follows:

[0018] The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh cells are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. The spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and the PMMA layer due to extrusion expansion.

[0019] Based on the spatiotemporal evolution characteristics, inversion processing is performed to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of the flow stagnation events of the PC melt and the PMMA melt respectively;

[0020] Based on the hydrodynamic anomaly and the respective delivery flow rates of the PC melt and the PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and the PMMA melt over time.

[0021] Preferably, in S400, according to the melt driving strategy, multi-channel verification is performed on the PC melt and the PMMA melt respectively to determine the conveying channel configuration parameters, specifically:

[0022] Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; wherein, each conveying channel has a preset channel diameter and channel direction angle;

[0023] Based on the melt driving strategy and the plurality of conveying channels, multi-conveyor channel simulation verification is performed on the PC melt and the PMMA melt respectively to obtain the conveying dynamic parameters of the PC melt and the PMMA melt in each conveying channel.

[0024] Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to the several conveying channels to determine the conveying channel structure parameters suitable for each of the PC melt and the PMMA melt.

[0025] On the other hand, the present invention provides a process optimization system for co-extrusion composite back cover of PC and PMMA, the system comprising the following modules:

[0026] The interface determination module is used to perform back cover modeling analysis and determine the interface between the PC melt and PMMA melt during co-extrusion casting.

[0027] The melt motion determination module is used to determine the motion properties of the PC melt and the PMMA melt based on the interface.

[0028] The morphology difference prediction module is used to determine the flow difference between the PC melt and the PMMA melt based on the motion properties and melt properties, thereby predicting the morphology difference between the PC layer and the PMMA layer after extrusion.

[0029] The fluid anomaly determination module is used to perform numerical analysis on the morphological differences to determine the fluid dynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting.

[0030] The strategy generation module is used to generate a melt driving strategy based on the hydrodynamic anomaly.

[0031] The verification and configuration module is used to perform multi-delivery channel verification on the PC melt and the PMMA melt respectively according to the melt driving strategy, so as to determine the delivery channel configuration parameters.

[0032] Preferably, the interface determination module is used to perform back cover modeling analysis to determine the interface between the PC melt and the PMMA melt during co-extrusion casting, specifically:

[0033] The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained, and the three-dimensional structural data are subjected to mesh finite element modeling analysis to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold; wherein, the co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt.

[0034] Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the co-extrusion casting process in the back cover mold.

[0035] The melt motion determination module is used to determine the motion properties of the PC melt and the PMMA melt based on the interface, specifically:

[0036] Using the interface as a reference, the multimodal motion parameters of the PC melt and the PMMA melt inside the rear cover mold are compared to determine the relative motion deviation between the PC melt and the PMMA melt; wherein, the multimodal motion parameters include motion direction and motion speed.

[0037] Preferably, the morphology difference prediction module is used to determine the flow difference between the PC melt and the PMMA melt based on the motion properties and melt properties, thereby predicting the morphology difference between the extruded PC layer and the PMMA layer, specifically as follows:

[0038] Based on the melt viscosity of the PC melt and the PMMA melt and the relative motion deviation attribute, the flow velocity gradient distribution of the PC melt and the PMMA melt in the three-dimensional space is obtained; by comparing the flow velocity gradient distribution of the PC melt and the PMMA melt, the difference in flow velocity gradient distribution between the PC melt and the PMMA melt is obtained.

[0039] The difference in flow velocity gradient distribution is converted by time integration to predict the position of the outer peripheral surface of the PC melt and the PMMA melt respectively; the outer peripheral surface positions of the PC melt and the PMMA melt are compared to determine the shape difference of the PC layer and PMMA layer formed after extrusion of the PC melt and PMMA melt; wherein, the shape difference includes the dimensional offset of the PC layer and PMMA layer due to extrusion expansion.

[0040] Preferably, the fluid anomaly determination module is used to perform numerical analysis on the morphological differences to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting, specifically:

[0041] The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh cells are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. The spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and the PMMA layer due to extrusion expansion.

[0042] Based on the spatiotemporal evolution characteristics, inversion processing is performed to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of the flow stagnation events of the PC melt and the PMMA melt respectively;

[0043] The strategy generation module is used to generate a melt driving strategy based on the hydrodynamic anomaly, specifically:

[0044] Based on the hydrodynamic anomaly and the respective delivery flow rates of the PC melt and the PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and the PMMA melt over time.

[0045] Preferably, the verification and configuration module is used to perform multi-delivery channel verification on the PC melt and the PMMA melt respectively according to the melt driving strategy, so as to determine the delivery channel configuration parameters, specifically:

[0046] Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; wherein, each conveying channel has a preset channel diameter and channel direction angle;

[0047] Based on the melt driving strategy and the plurality of conveying channels, multi-conveyor channel simulation verification is performed on the PC melt and the PMMA melt respectively to obtain the conveying dynamic parameters of the PC melt and the PMMA melt in each conveying channel.

[0048] Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to the several conveying channels to determine the conveying channel structure parameters suitable for each of the PC melt and the PMMA melt.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention provides a method and system for optimizing the co-extrusion composite back cover process of PC and PMMA. This involves back cover modeling and analysis to determine the interface between the PC melt and PMMA melt during co-extrusion casting, thereby determining the motion properties of the PC melt and PMMA melt. Based on the motion and melt properties, the flow differences between the PC melt and PMMA melt are determined, thereby predicting the morphological differences between the extruded PC layer and PMMA layer. Numerical analysis of the morphological differences is performed to determine the hydrodynamic anomalies of the PC melt and PMMA melt during co-extrusion casting, generating a melt driving strategy. Based on the melt driving strategy, multi-channel verification is implemented for both the PC melt and PMMA melt to determine the conveyor channel configuration parameters. Through back cover modeling and analysis, the interface between PC and PMMA during co-extrusion is determined, characterizing the flow and morphological differences between the two melts. Furthermore, a melt driving strategy and adapted conveyor channel configuration parameters are generated, optimizing the co-extrusion process at both the hardware and operational levels and improving the yield rate. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0052] Figure 1 This is a flowchart of the optimized process for the co-extrusion composite back cover of PC and PMMA provided by the present invention.

[0053] Figure 2 It is a co-extrusion finite element model of PC melt and PMMA melt.

[0054] Figure 3 It is the velocity of PC melt and PMMA melt.

[0055] Figure 4 It is the flow velocity gradient distribution of PC melt and PMMA melt.

[0056] Figure 5 It is a simulation verification of multiple delivery channels.

[0057] Figure 6 This is a structural diagram of the PC and PMMA co-extrusion composite back cover process optimization system provided by the present invention. Detailed Implementation

[0058] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and not for limiting the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all structures. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0059] The terms "comprising" and "having," and any variations thereof, used in this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0060] 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.

[0061] Please see Figure 1 As shown, this invention provides an optimized process for co-extruded composite back cover of PC and PMMA, the method comprising the following steps:

[0062] S100: Perform back cover modeling analysis to determine the interface between PC melt and PMMA melt during co-extrusion casting; based on the interface, determine the motion properties of PC melt and PMMA melt.

[0063] Furthermore, in S100, a back cover modeling analysis is performed to determine the interface between the PC melt and the PMMA melt during co-extrusion casting; based on the interface, the motion properties of the PC melt and the PMMA melt are determined, specifically:

[0064] The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained. Mesh finite element modeling analysis is performed on the three-dimensional structural data to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold. The co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt.

[0065] Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the filling process of the back cover mold during co-extrusion casting.

[0066] Using the interface as a reference, the multimodal motion parameters of PC melt and PMMA melt inside the back cover mold are compared to determine the relative motion deviation between PC melt and PMMA melt; among which, the multimodal motion parameters include motion direction and motion speed.

[0067] The process of co-extruding PC and PMMA to manufacture mobile phone back covers mainly includes two steps: material co-extrusion and material filling. In the co-extrusion step, PC and PMMA materials are heated separately into PC melt and PMMA melt, respectively. These melts are then transported to the co-extrusion channel through PC melt conveying channels and PMMA melt conveying channels, where the PC melt and PMMA melt form a composite material (i.e., co-extruded melt) inside the co-extrusion channel. Please refer to [link / reference]. Figure 2It is understood that the PC melt delivery channel and the PMMA melt delivery channel are respectively connected to the PC melt generation end and the PMMA melt generation end (not shown in the figure). The PC melt generation end and the PMMA melt generation end can independently adjust at least one of the following: the delivery flow rate, the delivery speed, and the delivery pressure of the PC melt and the PMMA melt. The material filling process involves delivering the above-mentioned composite material to the inside of the back cover mold. Under pressure, the composite material will gradually fill the inside of the back cover mold. After the composite material has completely filled the back cover mold, the solid mobile phone back cover component will be obtained through a demolding operation. In the material co-extrusion process, the structural shape of the co-extrusion equipment and the delivery drive parameters of the melt directly affect the fusion morphology of the PC melt and PMMA melt inside the composite material. The fusion morphology may include, but is not limited to, the shape and / or area of ​​the contact interface between the PC melt and the PMMA melt, thereby affecting the degree of material fusion within the composite material. Figure 2 It can be seen that by performing mesh finite element modeling analysis on the PC melt conveying channel, PMMA melt conveying channel and co-extrusion channel, the shape and / or area of ​​the contact interface between PC melt and PMMA melt in the composite material formed by the co-extrusion channel can be obtained.

[0068] As a filling and shaping mold for composite materials, the back cover mold is understood to have at least one co-extrusion melt input end, which is connected to the outlet of the co-extrusion channel to receive the co-extruded composite material. When the composite material is delivered to the back cover mold, it fills the internal space of the mold. The filling path is related to the shape, structure, and size of the mold's interior. Generally, the composite material first fills the larger areas inside the mold (such as the gap area corresponding to the back cover panel), while the smaller areas (such as the gap area corresponding to the back cover frame) are filled by the composite material in the final stage. During the filling process, the contact interface between the PC melt and PMMA melt within the composite material changes position and twists. This causes the movement direction and speed of the PC melt and PMMA melt to become inconsistent, potentially leading to separation between the two melts and affecting the tightness of the co-extrusion mixing of the two melts inside the back cover.

[0069] Therefore, it is evident that the morphological changes at the interface between the PC melt and PMMA melt in the composite material during the filling process directly affect the co-extrusion mixing density of the two melts. To ensure the stability of the co-extrusion mixing of the two melts in the composite material and to avoid the separation of different melts, a mesh finite element modeling analysis was first performed based on the three-dimensional structural data (such as three-dimensional shape and size data) of the back cover mold and all its co-extrusion melt input ends to simulate the dynamic filling path of the composite material (i.e., the co-extrusion melt) as it is transported into the back cover mold. The aforementioned dynamic filling path can be, but is not limited to, the movement path of the composite material from the initial transport into the back cover mold to the complete filling of all spaces inside the back cover mold. This movement path reflects the filling trajectory of the composite material inside the back cover mold. During the filling process of the composite material, the movement direction and speed of the PC melt and PMMA melt within the composite material will differ. This difference is related to the contact interface between the PC melt and PMMA melt. The greater the distortion of this contact interface during the filling process, the greater the difference in movement direction and speed between the PC melt and PMMA melt, and the easier it is for them to separate. Conversely, the smaller the distortion of the contact interface during the filling process (e.g., the contact interface maintains a smooth, extended state throughout the filling process), the smaller the difference in movement direction and speed between the PC melt and PMMA melt, and the less likely they are to separate. Therefore, based on the aforementioned dynamic filling path and the contact boundary between the PC melt and PMMA melt, spatial fitting is performed to determine the interface formed by the contact between the PC melt and PMMA melt during co-extrusion casting and filling inside the back cover mold. Then, using this interface as a reference, the movement direction and speed of the PC melt and PMMA melt inside the back cover mold are compared to determine the relative motion deviation attribute between the PC melt and PMMA melt. This relative motion deviation attribute can be, but is not limited to, deviations in parameters such as movement direction and / or speed between the PC melt and PMMA melt. Please refer to [link to relevant documentation]. Figure 3 The corresponding velocity distribution of PC melt and PMMA melt at positions along the direction parallel to the aforementioned interface, from Figure 3 It is evident that the movement rate of PMMA melt is always slightly lower than that of PC melt. This difference in movement rate, accumulated over a long period of time, will lead to the separation of PC melt and PMMA melt.

[0070] S200: Based on the motion and melt properties, determine the flow difference between PC melt and PMMA melt, and use this to predict the morphological difference between the extruded PC layer and PMMA layer.

[0071] Furthermore, in S200, the flow difference between PC melt and PMMA melt is determined based on kinematic and melt properties, thereby predicting the morphological difference between the extruded PC layer and PMMA layer. Specifically:

[0072] Based on the melt viscosity and relative motion deviation properties of PC melt and PMMA melt, the flow velocity gradient distribution of PC melt and PMMA melt in three-dimensional space is obtained; by comparing the flow velocity gradient distribution of PC melt and PMMA melt, the difference in flow velocity gradient distribution between PC melt and PMMA melt is obtained.

[0073] The differences in flow velocity gradient distribution are transformed by time integration to predict the positions of the outer peripheral surfaces of PC melt and PMMA melt. By comparing the positions of the outer peripheral surfaces of PC melt and PMMA melt, the shape differences of the PC layer and PMMA layer formed after extrusion are determined. The shape differences include the dimensional offsets of the PC layer and PMMA layer caused by extrusion expansion.

[0074] As described above, the PC melt and PMMA melt differ in parameters such as direction and speed of movement during the filling process inside the back cover mold. Furthermore, they also differ in material properties such as melt viscosity. These two factors combined result in a non-uniform distribution of the flow velocity gradient of the PC melt and PMMA melt within the three-dimensional space of the back cover mold. Here, the three-dimensional dimension refers to the X, Y, and Z directions corresponding to a three-dimensional coordinate system established within the back cover mold; the flow velocity gradient refers to the gradient value of the flow velocity of the PC melt and PMMA melt in the X, Y, and Z directions, reflecting the rate of change of the flow velocity of the PC melt and PMMA melt in the X, Y, and Z directions with spatial position. It can be understood that the above flow velocity gradient distribution reflects the cumulative spatial change of the flow velocity of the PC melt or PMMA melt in a specific direction (such as any one of the X, Y, or Z directions). Please refer to [link to relevant documentation]. Figure 4 The corresponding flow velocity gradient distribution of PC melt and PMMA melt in the X direction, from Figure 4 It can be seen that the flow velocity gradient along the X direction of PC melt and PMMA melt varies with different magnitudes during the flow process. This indicates that the flow velocities of PC melt and PMMA melt in the X direction cannot be kept consistent, causing PC melt and PMMA melt to deviate during the flow process.

[0075] When the mixed material is extruded from the co-extrusion channel, the PC melt and PMMA melt undergo extrusion swell. This extrusion swell is related to the material properties and flow velocity of the melts themselves. It is understood that if the PC melt and PMMA melt have the same flow velocity gradient distribution, or if the difference in their flow velocity gradient distributions is less than a preset difference threshold, the difference in extrusion swell caused solely by the difference in material properties between the PC melt and PMMA melt can be ignored. However, if the difference in flow velocity gradient distribution between the PC melt and PMMA melt is greater than or equal to the preset difference threshold, the difference in extrusion swell caused by this difference in flow velocity gradient distribution will affect the shape and dimensional consistency of the PC and PMMA layers formed after extrusion. This effect on the shape and dimensional consistency of the PC and PMMA layers may include, but is not limited to, different extrusion swell rates in the X, Y, and Z directions, resulting in inconsistent shape and size between the extruded PC and PMMA layers, leading to dimensional deviations between the PC and PMMA layers. The aforementioned size offset may include, but is not limited to, the size of the PC layer being smaller than the size of the PMMA layer, or the size of the PC layer being larger than the size of the PMMA layer. Both of these situations will cause the boundaries of the PC layer and the boundaries of the PMMA layer to be misaligned.

[0076] As shown above, the difference in flow velocity gradient distribution between PC melt and PMMA melt directly affects the degree of extrusion swell of both PC melt and PMMA melt, and this degree of swell is cumulatively related to the flow velocity gradient distribution over time. Therefore, a time-integral transformation is performed on the difference in flow velocity gradient distribution to predict the outer peripheral surface positions of the PC melt and PMMA melt. These outer peripheral surface positions determine the outer peripheral surface positions of the PC layer and PMMA layer formed after extrusion swell. By comparing the outer peripheral surface positions of the PC melt and PMMA melt, the shape differences of the PC layer and PMMA layer formed after extrusion are determined, thereby quantitatively identifying the dimensional deviations of the PC layer and PMMA layer, providing a basis for subsequent adjustments to the driving and conveying behavior of the PC melt and PMMA melt.

[0077] S300: Perform numerical analysis on morphological differences to determine the hydrodynamic anomalies of PC melt and PMMA melt during co-extrusion casting; generate melt driving strategies based on the hydrodynamic anomalies.

[0078] Furthermore, in S300, numerical analysis is performed on morphological differences to determine the hydrodynamic anomalies of PC melt and PMMA melt during co-extrusion casting; based on the hydrodynamic anomalies, a melt driving strategy is generated, specifically:

[0079] The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh elements are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. Among them, the spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and PMMA layer due to extrusion expansion.

[0080] Inversion processing is performed based on spatiotemporal evolution characteristics to determine the hydrodynamic anomalies of PC melt and PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of flow stagnation events of PC melt and PMMA melt respectively.

[0081] Based on the hydrodynamic anomalies and the respective delivery flow rates of the PC melt and PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and PMMA melt over time.

[0082] As the foregoing analysis shows, the shape difference between the PC layer and the PMMA layer is caused by the difference in the flow velocity gradient distribution between the PC melt and the PMMA melt. To suppress this shape difference, the movement rate of the PC melt and / or PMMA melt can be adjusted to ensure that the flow velocity gradient distribution of the PC melt and PMMA melt remains consistent during the filling of the internal space of the back cover mold. Specifically, the above-mentioned shape difference is mapped to three-dimensional space to obtain a three-dimensional dimensional offset distribution, which may include, but is not limited to, the dimensional deviations of the PC layer and the PMMA layer in various dimensions of three-dimensional space. The above-mentioned three-dimensional dimensional offset distribution is meshed and the mesh element numerical calculation is performed (that is, the above-mentioned three-dimensional dimensional deviation distribution is divided into mesh finite element segments and the spatiotemporal variation of the dimensional deviation direction and deviation value of each mesh element is calculated) to obtain the time and location of the boundary alignment deterioration of the PC layer and PMMA layer due to extrusion expansion; wherein the time of the boundary alignment deterioration refers to the time when the dimensional deviation of the PC layer and PMMA layer formed by PC melt and PMMA melt extrusion exceeds the preset deviation threshold; the location of the boundary alignment deterioration refers to the location where the dimensional deviation of the PC layer and PMMA layer formed by PC melt and PMMA melt extrusion exceeds the preset deviation threshold.

[0083] Given that the morphological differences between the PC and PMMA layers are caused by the difference in flow velocity gradient distribution between the PC melt and PMMA melt, a hydrodynamic model of the PC melt and PMMA melt within the back cover mold is constructed to invert the spatiotemporal evolution characteristics of these morphological differences. This allows for the determination of the occurrence time and location of flow stagnation events for both the PC melt and PMMA melt during co-extrusion casting. Specifically, a flow stagnation event refers to an event in which the actual flow velocity of both the PC melt and PMMA melt within the back cover mold along a certain direction is less than a preset velocity threshold for a duration exceeding a preset time threshold. Based on the occurrence time and location of the aforementioned flow stagnation events, as well as the respective flow rates of the PC melt and PMMA melt under preset baseline conveying conditions, pumping pressure variation configurations are generated for the PC melt and PMMA melt, respectively. By adjusting the magnitude of the melt pumping pressure change over time in the PC melt conveying channel and the PMMA melt conveying channel, dynamic adjustment of the pumping of the PC melt and PMMA melt is achieved, suppressing the flow velocity difference between the PC melt and PMMA melt, and synchronizing the flow velocities of the PC melt and PMMA melt.

[0084] S400: Based on the melt drive strategy, multiple delivery channels are verified for PC melt and PMMA melt respectively to determine the delivery channel configuration parameters.

[0085] Furthermore, in S400, based on the melt drive strategy, multi-channel verification is performed on both PC melt and PMMA melt to determine the conveyor channel configuration parameters, specifically:

[0086] Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; each conveying channel has a preset channel diameter and channel direction angle.

[0087] Based on the melt driving strategy and several conveying channels, multi-conveyor channel simulation verification was carried out on PC melt and PMMA melt respectively to obtain the conveying dynamic parameters of PC melt and PMMA melt in each conveying channel.

[0088] Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to several conveying channels to determine the appropriate conveying channel structural parameters for PC melt and PMMA melt.

[0089] It is understandable that the above melt drive configuration sets the pumping parameters for the melt from a melt hydrodynamic perspective. Based on this configuration, the pumping pressure parameters of the melt within the PC and PMMA melt delivery channels can be determined. Furthermore, the external structural parameters of the melt delivery channels (such as channel diameter and channel orientation angle) also affect the melt delivery flow velocity; that is, the melt drive configuration and the external structural parameters jointly influence the melt delivery flow velocity. To find the optimal external structural parameters of the melt delivery channels given the determined melt drive configuration, a set of delivery channels is constructed. This set includes several delivery channels, each with a preset different channel diameter and channel orientation angle. Using the above melt drive configuration as a preset condition, hydrodynamic state simulations of PC and PMMA melts are performed on each delivery channel to obtain the respective delivery dynamic parameters of PC and PMMA melts in each delivery channel (such as dynamic melt flow velocity and dynamic melt pressure). Please refer to [link to relevant documentation]. Figure 5 This demonstrates the dynamic flow velocity distribution of the melt within the conveying channels corresponding to three different channel orientation angles. Then, multi-objective optimization (e.g., through a multi-objective optimization function) is performed on the conveying dynamic parameters of all conveying channels under the conveying channel set to determine the appropriate conveying channel structural parameters for PC melt and PMMA melt (e.g., the final channel diameter and final channel orientation angle for each). Subsequently, based on the aforementioned conveying channel structural parameters and the melt driving strategy, the hardware and operational configuration for co-extruding PC and PMMA to prepare mobile phone back covers is set, effectively improving the yield rate.

[0090] Please see Figure 6 As shown, this invention provides a process optimization system for co-extruded composite back cover of PC and PMMA, which includes the following modules:

[0091] The interface determination module is used to perform back cover modeling analysis and determine the interface between the PC melt and PMMA melt during co-extrusion casting.

[0092] The melt motion determination module is used to determine the motion properties of PC melt and PMMA melt based on the interface.

[0093] The morphology difference prediction module is used to determine the flow difference between PC melt and PMMA melt based on motion properties and melt properties, thereby predicting the morphology difference between the extruded PC layer and PMMA layer.

[0094] The fluid anomaly determination module is used to perform numerical analysis on morphological differences and determine the fluid dynamic anomalies of PC melt and PMMA melt during co-extrusion casting.

[0095] The strategy generation module is used to generate melt-driving strategies based on hydrodynamic anomalies.

[0096] The verification and configuration module is used to perform multi-channel verification on PC melt and PMMA melt according to the melt driving strategy, so as to determine the configuration parameters of the conveying channels.

[0097] Furthermore, the interface determination module is used to perform back cover modeling analysis to determine the interface between the PC melt and the PMMA melt during co-extrusion casting, specifically:

[0098] The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained. Mesh finite element modeling analysis is performed on the three-dimensional structural data to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold. The co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt.

[0099] Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the filling process of the back cover mold during co-extrusion casting.

[0100] The melt motion determination module is used to determine the motion properties of PC melt and PMMA melt based on the interface, specifically:

[0101] Using the interface as a reference, the multimodal motion parameters of PC melt and PMMA melt inside the back cover mold are compared to determine the relative motion deviation between PC melt and PMMA melt; among which, the multimodal motion parameters include motion direction and motion speed.

[0102] Furthermore, the morphology difference prediction module is used to determine the flow difference between PC melt and PMMA melt based on motion properties and melt properties, thereby predicting the morphology difference between the extruded PC layer and PMMA layer, specifically:

[0103] Based on the melt viscosity and relative motion deviation properties of PC melt and PMMA melt, the flow velocity gradient distribution of PC melt and PMMA melt in three-dimensional space is obtained; by comparing the flow velocity gradient distribution of PC melt and PMMA melt, the difference in flow velocity gradient distribution between PC melt and PMMA melt is obtained.

[0104] The differences in flow velocity gradient distribution are transformed by time integration to predict the positions of the outer peripheral surfaces of PC melt and PMMA melt. By comparing the positions of the outer peripheral surfaces of PC melt and PMMA melt, the shape differences of the PC layer and PMMA layer formed after extrusion are determined. The shape differences include the dimensional offsets of the PC layer and PMMA layer caused by extrusion expansion.

[0105] Furthermore, the fluid anomaly determination module is used to perform numerical analysis of morphological differences to determine the hydrodynamic anomalies of PC melt and PMMA melt during co-extrusion casting, specifically:

[0106] The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh elements are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. Among them, the spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and PMMA layer due to extrusion expansion.

[0107] Inversion processing is performed based on spatiotemporal evolution characteristics to determine the hydrodynamic anomalies of PC melt and PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of flow stagnation events of PC melt and PMMA melt respectively.

[0108] The strategy generation module is used to generate melt-driving strategies based on hydrodynamic anomalies, specifically:

[0109] Based on the hydrodynamic anomalies and the respective delivery flow rates of the PC melt and PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and PMMA melt over time.

[0110] Furthermore, the verification and configuration module is used to perform multi-channel verification on PC melt and PMMA melt respectively according to the melt driving strategy, thereby determining the conveyor channel configuration parameters, specifically:

[0111] Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; each conveying channel has a preset channel diameter and channel direction angle.

[0112] Based on the melt driving strategy and several conveying channels, multi-conveyor channel simulation verification was carried out on PC melt and PMMA melt respectively to obtain the conveying dynamic parameters of PC melt and PMMA melt in each conveying channel.

[0113] Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to several conveying channels to determine the appropriate conveying channel structural parameters for PC melt and PMMA melt.

[0114] The PC and PMMA co-extrusion composite back cover process optimization system of the present invention has the same operation and effect as the PC and PMMA co-extrusion composite back cover process optimization method described above, and will not be described again here.

[0115] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of a necessary general-purpose hardware platform, or by a combination of hardware and software. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a computer product. The present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Other embodiments may also be used. 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 of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optimized process for co-extruded composite back cover of PC and PMMA, characterized in that, The method includes the following steps: S100: Perform back cover modeling analysis to determine the interface between PC melt and PMMA melt during co-extrusion casting; determine the motion properties of PC melt and PMMA melt based on the interface; S200: Based on the motion properties and melt properties, determine the flow difference between the PC melt and the PMMA melt, thereby predicting the morphological difference between the PC layer and the PMMA layer after extrusion; S300: Perform numerical analysis on the morphological differences to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; generate a melt driving strategy based on the hydrodynamic anomalies. S400: According to the melt driving strategy, perform multi-delivery channel verification on the PC melt and the PMMA melt respectively to determine the delivery channel configuration parameters; In S300, numerical analysis is performed on the morphological differences to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; based on the hydrodynamic anomalies, a melt driving strategy is generated, specifically: The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh cells are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. The spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and the PMMA layer due to extrusion expansion. Based on the spatiotemporal evolution characteristics, inversion processing is performed to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of the flow stagnation events of the PC melt and the PMMA melt respectively; Based on the hydrodynamic anomaly and the respective delivery flow rates of the PC melt and the PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and the PMMA melt over time. In S400, based on the melt driving strategy, multi-channel verification is performed on the PC melt and the PMMA melt respectively to determine the conveying channel configuration parameters, specifically: Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; each conveying channel has a preset channel diameter and channel direction angle. Based on the melt driving strategy and the plurality of conveying channels, multi-conveyor channel simulation verification is performed on the PC melt and the PMMA melt respectively to obtain the conveying dynamic parameters of the PC melt and the PMMA melt in each conveying channel. Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to the several conveying channels to determine the conveying channel structure parameters suitable for each of the PC melt and the PMMA melt.

2. The optimized process for co-extruded composite back cover of PC and PMMA according to claim 1, characterized in that, In S100, a back cover modeling analysis is performed to determine the interface between the PC melt and the PMMA melt during co-extrusion casting; based on the interface, the motion properties of the PC melt and the PMMA melt are determined, specifically: The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained, and the three-dimensional structural data are subjected to mesh finite element modeling analysis to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold; wherein, the co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt. Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the co-extrusion casting process in the back cover mold. Using the interface as a reference, the multimodal motion parameters of the PC melt and the PMMA melt inside the rear cover mold are compared to determine the relative motion deviation between the PC melt and the PMMA melt; wherein, the multimodal motion parameters include motion direction and motion speed.

3. The optimized process for co-extruded composite back cover of PC and PMMA according to claim 2, characterized in that, In S200, based on the kinematic properties and melt properties, the flow difference between the PC melt and the PMMA melt is determined to predict the morphological difference between the extruded PC layer and the PMMA layer, specifically: Based on the melt viscosity of the PC melt and the PMMA melt and the relative motion deviation attribute, the flow velocity gradient distribution of the PC melt and the PMMA melt in the three-dimensional space is obtained; by comparing the flow velocity gradient distribution of the PC melt and the PMMA melt, the difference in flow velocity gradient distribution between the PC melt and the PMMA melt is obtained. The difference in flow velocity gradient distribution is converted by time integration to predict the position of the outer peripheral surface of the PC melt and the PMMA melt. The outer peripheral surface positions of the PC melt and the PMMA melt are compared to determine the shape difference of the PC layer and the PMMA layer formed after extrusion. The shape difference includes the dimensional offset of the PC layer and the PMMA layer due to extrusion expansion.

4. A system for optimizing the process of co-extruding composite back cover using PC and PMMA as described in any one of claims 1-3, characterized in that, The system includes the following modules: The interface determination module is used to perform back cover modeling analysis and determine the interface between the PC melt and PMMA melt during co-extrusion casting. The melt motion determination module is used to determine the motion properties of the PC melt and the PMMA melt based on the interface. The morphology difference prediction module is used to determine the flow difference between the PC melt and the PMMA melt based on the motion properties and melt properties, thereby predicting the morphology difference between the PC layer and the PMMA layer after extrusion. The fluid anomaly determination module is used to perform numerical analysis on the morphological differences to determine the fluid dynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting. The strategy generation module is used to generate a melt driving strategy based on the hydrodynamic anomaly. The verification and configuration module is used to perform multi-delivery channel verification on the PC melt and the PMMA melt respectively according to the melt driving strategy, so as to determine the delivery channel configuration parameters.

5. The system according to claim 4, characterized in that, The interface determination module is used to perform back cover modeling analysis to determine the interface between the PC melt and PMMA melt during co-extrusion casting, specifically: The three-dimensional structural data of the back cover mold and its co-extrusion melt input end are obtained, and the three-dimensional structural data are subjected to mesh finite element modeling analysis to simulate the dynamic filling path of the co-extrusion melt inside the back cover mold; wherein, the co-extrusion melt is formed by co-extrusion of PC melt and PMMA melt. Based on the filling dynamic path and the contact boundary between PC melt and PMMA melt in the co-extrusion melt, spatial fitting is performed to determine the interface formed by the contact between PC melt and PMMA melt during the co-extrusion casting process in the back cover mold. The melt motion determination module is used to determine the motion properties of the PC melt and the PMMA melt based on the interface, specifically: Using the interface as a reference, the multimodal motion parameters of the PC melt and the PMMA melt inside the rear cover mold are compared to determine the relative motion deviation between the PC melt and the PMMA melt; wherein, the multimodal motion parameters include motion direction and motion speed.

6. The system according to claim 5, characterized in that, The morphology difference prediction module is used to determine the flow difference between the PC melt and the PMMA melt based on the motion properties and melt properties, thereby predicting the morphology difference between the extruded PC layer and the PMMA layer, specifically: Based on the melt viscosity of the PC melt and the PMMA melt and the relative motion deviation attribute, the flow velocity gradient distribution of the PC melt and the PMMA melt in the three-dimensional space is obtained; by comparing the flow velocity gradient distribution of the PC melt and the PMMA melt, the difference in flow velocity gradient distribution between the PC melt and the PMMA melt is obtained. The difference in flow velocity gradient distribution is converted by time integration to predict the position of the outer peripheral surface of the PC melt and the PMMA melt. The outer peripheral surface positions of the PC melt and the PMMA melt are compared to determine the shape difference of the PC layer and the PMMA layer formed after extrusion. The shape difference includes the dimensional offset of the PC layer and the PMMA layer due to extrusion expansion.

7. The system according to claim 6, characterized in that, The fluid anomaly determination module is used to perform numerical analysis on the morphological differences to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting, specifically: The morphological differences are mapped to form a three-dimensional size offset distribution. The three-dimensional size offset distribution is then meshed and the mesh cells are numerically calculated to obtain the spatiotemporal evolution characteristics of the morphological differences. The spatiotemporal evolution characteristics include the time and location of the boundary alignment degradation of the PC layer and the PMMA layer due to extrusion expansion. Based on the spatiotemporal evolution characteristics, inversion processing is performed to determine the hydrodynamic anomalies of the PC melt and the PMMA melt during co-extrusion casting; wherein, the hydrodynamic anomalies include the occurrence time and location of the flow stagnation events of the PC melt and the PMMA melt respectively; The strategy generation module is used to generate a melt driving strategy based on the hydrodynamic anomaly, specifically: Based on the hydrodynamic anomaly and the respective delivery flow rates of the PC melt and the PMMA melt, a melt driving strategy is generated; wherein, the melt driving strategy includes configuring the pumping pressure of the PC melt and the PMMA melt over time.

8. The system according to claim 7, characterized in that, The verification and configuration module is used to perform multi-channel verification on the PC melt and the PMMA melt respectively according to the melt driving strategy, so as to determine the conveying channel configuration parameters, specifically: Based on the position and shape of the co-extrusion melt input end of the rear cover mold, several conveying channels are constructed; wherein, each conveying channel has a preset channel diameter and channel direction angle; Based on the melt driving strategy and the plurality of conveying channels, multi-conveyor channel simulation verification is performed on the PC melt and the PMMA melt respectively to obtain the conveying dynamic parameters of the PC melt and the PMMA melt in each conveying channel. Multi-objective optimization is performed based on the conveying dynamic parameters corresponding to the several conveying channels to determine the conveying channel structure parameters suitable for each of the PC melt and the PMMA melt.

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