Injection mold visual virtual design system

Abstract

The application discloses a kind of injection mold visual virtual design systems, it is related to the technical field of visual virtual design, the system includes: data acquisition module is used to obtain the flow position data and temperature distribution data in the injection filling process of simulating melt flow into target injection mold, flow position data includes the front position data of melt when flowing with time, temperature distribution data includes the temperature sequence data of each grid unit corresponding to target injection mold recorded according to preset time step;Data processing module is used to determine the first runner and the second runner when forming weld line in injection filling process;According to temperature distribution data, determine the temperature difference integral value between first runner and second runner;According to temperature difference integral value, determine the reason of weld line formation;Virtual design module is used to design the injection filling process of target injection mold according to forming reason.The application reduces the time required for mold design.

Description

Technical Field

[0001] This invention relates to the technical field of visual virtual design, and more particularly to a visual virtual design system for injection molds. Background Technology

[0002] Weld lines are among the most common defects in injection molded products. They occur in most injection molded parts (typically a line or V-groove), except for a few geometrically very simple parts, especially large and complex parts requiring multi-gate molds and inserts. Weld lines not only affect the appearance of the molded part but also influence its mechanical properties, such as impact strength, tensile strength, and elongation at break. Furthermore, weld lines significantly impact product design and part lifespan; therefore, they should be avoided or improved as much as possible.

[0003] In the prior art, for example, Chinese Patent No. CN104669518A discloses a CAE auxiliary device for injection mold design. The device uses the simulation analysis report as a reference to design the mold, avoiding the disadvantages of direct design, eliminating the need for repeated modifications, improving work efficiency, and reducing defects in mold design.

[0004] However, regarding the issue of weld lines, existing technology generally considers that weld lines are often caused by poor welding due to excessively low material temperature. In this regard, the temperature of the barrel and nozzle can be appropriately increased or the injection cycle can be extended to promote the rise of material temperature. At the same time, the flow rate of cooling water in the mold should be controlled and the mold temperature should be appropriately increased.

[0005] This approach requires a significant amount of time for testing and verification during mold design, relying on engineers' experience and trial and error. It is not efficient enough in resolving weld lines during the design process, resulting in a substantial time commitment for mold design.

[0006] Therefore, how to reduce the time required for mold design has become a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The technical problem solved by this invention is that mold design requires a lot of time to eliminate weld lines.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a visualization virtual design system for injection molds, comprising:

[0009] The data acquisition module is used to acquire flow position data and temperature distribution data during the injection filling process of simulated melt flowing into the target injection mold. The flow position data includes the leading edge position data of the melt as it flows over time, and the temperature distribution data includes the temperature sequence data of each grid cell corresponding to the target injection mold, recorded according to a preset time step.

[0010] The data processing module is used for:

[0011] When forming the weld line during the injection molding filling process, a first gating channel and a second gating channel for forming the weld line are determined;

[0012] The integral value of the temperature difference between the first pouring channel and the second pouring channel is determined based on the temperature distribution data;

[0013] The cause of the weld line formation is determined based on the integral value of the temperature difference;

[0014] The virtual design module is used to design the injection filling process of the target injection mold based on the formation cause.

[0015] Preferably, the system further includes a data visualization module; the data processing module is further configured to:

[0016] The cumulative heat value during the period from the start of the melt filling of the grid cell to the end of the injection filling process is determined based on the temperature sequence data of each grid cell;

[0017] The data visualization module is used for:

[0018] The grid unit is divided into a first heat grid unit and a second heat grid unit according to the magnitude of the accumulated heat value;

[0019] The positions on the cavity model corresponding to the first heat grid unit and the second heat grid unit of the target injection mold are rendered using the first color and the second color respectively to obtain the rendered model;

[0020] The virtual design module is used to design the injection filling process of the target injection mold based on the rendering model and the formation reason.

[0021] Preferably, when forming the weld line during the injection molding process, before determining the first and second gating channels for forming the weld line, the data processing module is further configured to:

[0022] Determine whether weld lines appear during the injection molding process based on the flow position data;

[0023] When forming the weld line during the injection molding process, determining the first gating channel and the second gating channel for forming the weld line includes:

[0024] If a weld line appears during the injection molding process, then the first and second merging grid units that form the weld line are identified.

[0025] The melt flows into the first gating channel of the first confluence grid unit and the melt flows into the second gating channel of the second confluence grid unit;

[0026] Determining the integral value of the temperature difference between the first gating channel and the second gating channel based on the temperature distribution data includes:

[0027] The temperature values ​​of multiple grid cells on the first pouring channel are summed at multiple moments based on the temperature sequence data to obtain the first temperature summation sequence data of the first pouring channel;

[0028] The second temperature summation sequence data of the second pouring channel is obtained by summing the temperature values ​​of multiple grid cells on the second pouring channel at multiple times based on the temperature sequence data;

[0029] Determine the integral value of the temperature difference between the first temperature summation sequence data and the second temperature summation sequence data.

[0030] Preferably, the causes of formation include path thermal memory conflict and molecular orientation conflict; the virtual design module is further used for:

[0031] When the cause of formation is the path thermal memory conflict, the gate through which the melt enters the target injection mold is determined according to the rendering model;

[0032] When the cause of formation is the molecular orientation conflict, the pouring speed sequence data of the melt being poured into the target injection mold is determined according to the rendering model.

[0033] Preferably, determining whether weld lines occur during the injection molding process based on the flow position data includes:

[0034] Based on the flow position data, determine whether the melt has multiple independent melt flow fronts;

[0035] If multiple independent melt flow fronts are identified, the area where at least two of the multiple independent melt flow fronts intersect is defined as the intersection zone;

[0036] If the junction area exists, it is determined that a weld line appears in the junction area during the injection molding process;

[0037] If a weld line appears during the injection molding process, the first and second merging mesh units that form the weld line are determined, including:

[0038] The grid cells that the first melt flow front and the second melt flow front come into contact with at the moment of their intersection are respectively defined as the first merging grid cell and the second merging grid cell.

[0039] Preferably, the data acquisition module is further configured to acquire the original gate of the injection molding filling process; determining the first gating channel where the melt flows to the first confluence grid unit and the second gating channel where the melt flows to the second confluence grid unit includes:

[0040] Starting from the first converging grid cell, the adjacent grid cells are iteratively searched along the backflow direction of the melt until the original gate is reached, thus obtaining the first search path;

[0041] Starting from the second merging grid cell, the adjacent grid cells are iteratively searched along the backflow direction of the melt until the original gate is reached, thus obtaining the second search path;

[0042] The set of multiple grid cells on the first search path is defined as the first pouring channel;

[0043] The set of multiple grid cells on the second search path is defined as the second gating channel.

[0044] The step of determining the cause of the weld line formation based on the integral value of the temperature difference includes:

[0045] If the integral value of the temperature difference is greater than the preset integral threshold of the temperature difference, then the cause of the formation is determined to be the path thermal memory conflict.

[0046] If the integral value of the temperature difference is less than or equal to the preset integral threshold of the temperature difference, then the cause of formation is determined to be the molecular orientation conflict.

[0047] Preferably, when the cause of formation is the path thermal memory conflict, determining the gate for the melt to enter the target injection mold based on the rendering model includes:

[0048] If the cause of formation is the path thermal memory conflict, then the concentrated area of ​​the first thermal grid cell is determined in the rendering model;

[0049] Determine the center coordinates of the spatial geometric center points among multiple first thermal grid units within the concentrated area in the first coordinate system of the rendered model;

[0050] Obtain the gate position coordinates of the original gate in the second coordinate system of the target injection mold;

[0051] Transform the center coordinates in the first coordinate system to the second coordinate system to obtain the center position coordinates;

[0052] The direction of the vector pointing from the center position coordinates to the gate position coordinates is determined as the offset direction;

[0053] Determine the first theoretical flow length of the first gating channel and the second theoretical flow length of the second gating channel;

[0054] The base offset is determined based on the difference between the first theoretical flow length and the second theoretical flow length;

[0055] The original gate is moved along the offset direction according to the basic offset to obtain the gate through which the melt is poured into the target injection mold.

[0056] Preferably, when the formation cause is the molecular orientation conflict, determining the pouring speed sequence data of the melt into the target injection mold based on the rendering model includes:

[0057] Obtain the injection speed curve as a function of time during the current injection molding process;

[0058] In the rendering model, the multiple mesh cells occupied by the fusion line are determined;

[0059] Determine multiple time data points at which the multiple second thermal grid cells occupied by the weld line begin to be filled by the melt;

[0060] The filling period is determined based on multiple time data points showing when the multiple second heat grid cells occupied by the fusion line begin to be filled by the melt;

[0061] Determine the injection speed curve segment corresponding to the filling time period from the injection speed curve;

[0062] Determine the velocity fluctuation amplitude in the injection velocity curve segment;

[0063] The speed fluctuation amplitude is suppressed according to a preset suppression ratio to obtain a pouring speed curve segment;

[0064] Replace the injection speed curve segment in the injection speed curve with the pouring speed curve segment to obtain the pouring speed curve.

[0065] Preferably, the step of summing the temperature values ​​of multiple grid cells on the first casting channel based on multiple moments of the temperature sequence data to obtain the first total temperature sequence data of the first casting channel includes:

[0066] The first summation start time is determined from a plurality of filling start times in which each of the plurality of grid cells on the first pouring channel begins to be filled by the melt;

[0067] The formation time of the fusion line is determined as the end time of the summation;

[0068] Based on the time step, a plurality of first reference times are determined between the first summation start time and the summation end time;

[0069] The first temperature sum sequence data is obtained by summing the temperature values ​​of multiple grid cells on the first pouring channel based on the multiple first reference times;

[0070] The step of summing the temperature values ​​of multiple grid cells on the second casting channel based on the temperature sequence data at multiple times to obtain the second temperature summation sequence data of the second casting channel includes:

[0071] The second summation start time is determined from a plurality of filling start times in which each of the plurality of grid cells on the second pouring channel begins to be filled by the melt;

[0072] Based on the time step, a plurality of second reference times are determined between the second summation start time and the summation end time;

[0073] The second temperature sum sequence data is obtained by summing the temperature values ​​of multiple grid cells on the second pouring channel based on the multiple second reference times.

[0074] Preferably, determining the integral value of the temperature difference between the first gating channel and the second gating channel based on the temperature distribution data includes:

[0075] The grid cell with the largest cumulative heat value in the first pouring channel is determined as the first representative cell;

[0076] The grid cell with the largest cumulative heat value in the second pouring channel is determined as the second representative cell;

[0077] The absolute temperature difference integral value at each time point between the temperature sequence data of the first representative unit and the temperature sequence data of the second representative unit is determined as the temperature difference integral value between the first pouring channel and the second pouring channel.

[0078] The beneficial effects of this invention are as follows: By capturing dynamic flow position data and global temperature sequence data recorded according to time steps during the injection molding process, the thermal history evolution information along the melt flow path is completely preserved, overcoming the shortcomings of traditional CAE visualization which only renders static temperature fields and discards process history data; furthermore, by identifying the specific gating channels corresponding to the weld lines and calculating the thermal differential integral values ​​between their paths... The TDIV (Temperature Difference in Quantity) quantifies the cumulative difference in thermal history between two melt streams from the gate to the junction. TDIV accurately characterizes the core mechanism causing weld line defects—the cumulative difference in molecular chain mobility. Based on this, the system can scientifically diagnose whether the root cause of weld lines is a path thermal memory conflict (reflecting uneven thermal history caused by runner length imbalance) or a molecular orientation conflict (reflecting molecular chain orientation disorder caused by abrupt changes in shear rate at the junction). This solves the problem that existing technologies cannot distinguish between structural design defects and improper process parameters. Finally, the virtual design module drives targeted optimization strategies based on the diagnosis results—if it is a path conflict, the mold structure (such as gate position and runner layout) is adjusted to balance the thermal history; if it is an orientation conflict, the process parameters (such as injection speed curve and gate sequence) are adjusted to improve the flow field dynamics, thereby fundamentally eliminating weld line defects. This significantly reduces the number of mold reworks and design correction cycles required by traditional experience-based trial and error, achieving precise and efficient virtual iteration of injection mold design. Attached Figure Description

[0079] Figure 1 This is a schematic diagram of the basic structure of a visualization virtual design system for injection molds, provided as an embodiment of the present invention. Detailed Implementation

[0080] 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. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0081] In the injection molding process of polymer materials, the core cause of weld line defects lies in the insufficient diffusion of molecular chains when two melt streams converge. Traditional technologies rely on instantaneous temperature difference detection at the convergence point (e.g., a 10°C temperature difference), but ignore the cumulative effect of the entire thermal history of the melt flowing from the gate to the convergence point. The mobility of polymer material molecular chains is dominated by a continuous temperature change process, not determined by a single point temperature. Therefore, existing systems have the following shortcomings: Although CAE systems calculate unit-level temperature time series (e.g., 0.1-second intervals), the visualization interface only renders the static temperature field at the final moment, discarding historical process data; it cannot distinguish between path design errors (differences in runner length) and improper process parameters (injection speed fluctuations); adjustments to the design scheme based on experience (e.g., uniformly offsetting the gate by 5mm) have a low success rate because they do not address the root cause of the problem, requiring a significant amount of time to revise the mold design.

[0082] The inventors of this application use the integral value of temperature difference as a criterion for the formation of weld lines, quantifying the degree of asymmetry in the thermal history of the two flow paths throughout the entire process, and reflecting the cumulative difference in the mobility of molecular chains.

[0083] The inventors of this application have discovered that the formation of fusion lines can be divided into path thermal memory conflict and molecular orientation conflict from the perspective of molecular motion.

[0084] The specific manifestation of path thermal memory conflict is as follows: In flow channels with significant length differences, the melt with a longer flow path experiences longer flow time and / or more cooling before reaching the junction, resulting in a higher average cooling rate. This significantly shortens the relaxation time of the melt molecular chains in that path, and the degree to which the molecular chain conformation is "frozen" is greater. Some melts may even prematurely enter a supercooled state or undergo local crystallization (increased crystallinity), and the mobility of molecular chains (such as diffusion capacity) is significantly reduced. Molecular chains with reduced mobility have difficulty achieving sufficient interdiffusion and entanglement with melt molecular chains from shorter paths with stronger mobility in the junction region. This results in insufficient intermolecular bonding forces at the melt interface, thus forming visible or invisible weld lines (insufficient microscopic bonding strength).

[0085] The specific manifestations of molecular orientation conflict are as follows: due to differences in inlet pressure, local cross-sectional changes, or inconsistent injection speed settings / fluctuations between the two flow channels, the two melt fronts have significantly different instantaneous flow velocities (i.e., huge differences in shear rates) at the junction point, or one melt stream collides perpendicularly with the sidewall of the other melt stream. The junction region generates drastic shear rate abrupt changes or extreme flow fields (such as stretching flow). Under strong shear or stretching flow fields, polymer chains will be highly oriented along the flow direction. When two melt streams with drastically different orientation states (e.g., one highly oriented, the other relatively random) or conflicting orientation directions (e.g., perpendicular intersection) meet, the molecular chains cannot coordinate and relax to a compatible state in a short time. This discontinuity in the orientation of the molecular chains in the interface region prevents effective mutual penetration and entanglement, thus forming weld lines (macroscopically often manifested as "V" shaped patterns or haze).

[0086] Crucially, path thermal memory conflict and molecular orientation conflict have different formation mechanisms, and therefore respond very differently to mold design and process parameter adjustments:

[0087] Path thermal memory conflict mainly reflects the cumulative difference in cooling history (temperature change history) caused by the difference in flow path length before the melt reaches the junction zone, which is essentially a design flaw. Therefore, it is necessary to modify the melt flow path itself, such as adjusting the gate position to reduce the difference between the longest and shortest runners, optimizing the cold / hot runner layout to ensure path balance, and even changing the product parting surface structure to achieve a more symmetrical filling pattern and a more balanced flow path thermal history;

[0088] Molecular orientation conflict primarily reflects the difference in kinetic energy (velocity) of the melt at the junction point and the molecular orientation disorder caused by extreme flow fields. This is more related to process control. Therefore, it is necessary to modify the melt pouring speed pattern, such as finely controlling the synchronous injection sequence and speed curves between multiple gates (e.g., matching the velocities of the two leading flows as much as possible), optimizing the holding pressure switching point to reduce the flow rate difference, and adjusting the local mold temperature (especially in the junction area) to promote molecular chain relaxation, etc.

[0089] Therefore, the key step in addressing weld line issues lies in accurately diagnosing and differentiating the causes of specific weld line defects: Is it primarily due to path thermal memory conflict, or molecular orientation conflict? Or is it a coupling of both? Then, based on the type of conflict, targeted injection mold design schemes or process parameters should be adjusted.

[0090] Based on in-depth research into the core physical quantities of the two conflict mechanisms (the cumulative difference in path thermal history and the instantaneous shear / tensile stress at the junction), the inventors of this application have discovered that path thermal memory conflict and molecular orientation conflict can be effectively distinguished by the "Thermal Differential Integral Value (TDIV)" corresponding to the junction point from the two casting channels forming the weld line (from their respective gate starting points). TDIV directly quantifies the difference in temperature change history (i.e., thermal history intensity) accumulated by the two melts throughout their entire flow path, and can well reflect the cumulative difference in molecular chain activity that leads to path thermal memory conflict. In contrast, although molecular orientation conflict is also related to temperature history to some extent (temperature affects viscosity, and thus affects shear), its core driving factor is the dynamic characteristics of the flow field at the moment of junction (abrupt shear rate change, orientation freezing). This transient characteristic is not easily captured by path accumulation quantities such as TDIV, especially when the TDIV value is small.

[0091] Furthermore, through extensive experimental verification and simulation analysis, this application establishes a quantitative criterion for distinguishing two conflict types for specific materials (taking polypropylene PP as an example).

[0092] When the temperature difference integral (TDIV) of the two channels corresponding to the polypropylene material exceeds the critical value of 8°C·s, it indicates that there is a significant inhomogeneity in the path thermal history of the two melts. The degree of difference is sufficient to ensure that the molecular diffusion depth of the longer melt path is lower than the critical value (e.g., 0.2 micrometers) required for the formation of effective molecular entanglement. At this time, the formation of the weld line will inevitably be mainly dominated by path thermal memory conflict. Specifically, this manifests as a significant cumulative difference in the mobility (diffusion capacity) of the molecular chains of the two melts caused by the difference in channel length.

[0093] When the TDIV corresponding to polypropylene material is less than or equal to 8 °C·s, the difference in the path thermal history between the two melts is small, and the cumulative effect of their path thermal history is insufficient to significantly inhibit molecular diffusion on its own. However, weld lines still appear, and their cause should be mainly attributed to molecular orientation conflict. Specifically, the mismatch in velocity or poor junction angle between the two melts at the intersection point triggers a drastic change in local shear rate, leading to abrupt changes in molecular chain orientation and disordered arrangement (such as conflict between highly oriented and randomly coiled melt interfaces), thereby preventing effective molecular chain entanglement and the formation of weld lines.

[0094] Specifically, please refer to Example 1, and refer to Figure 1 As one embodiment of the present invention, a visualization virtual design system for injection molds is provided, comprising:

[0095] The data acquisition module is used to acquire flow position data and temperature distribution data during the injection filling process of the simulated melt flowing into the target injection mold. The flow position data includes the front edge position data of the melt as it flows over time, and the temperature distribution data includes the temperature sequence data of each grid cell corresponding to the target injection mold, recorded according to a preset time step.

[0096] The data processing module is used to: determine the first and second gating channels that form the weld line during the injection molding filling process; determine the integral value of the temperature difference between the first and second gating channels based on temperature distribution data; and determine the cause of the weld line formation based on the integral value of the temperature difference.

[0097] The virtual design module is used to design the injection filling process of the target injection mold based on the cause of formation.

[0098] Preferably, the system further includes a data visualization module; a data processing module, further configured to: determine the cumulative heat value during the period from the start of melt filling of the grid cell to the end of the injection molding filling process based on the temperature sequence data of each grid cell; the data visualization module is configured to: divide the grid cell into a first heat grid cell and a second heat grid cell based on the magnitude of the cumulative heat value; render the positions on the cavity model corresponding to the first heat grid cell and the second heat grid cell respectively using a first color and a second color to obtain a rendering model; and a virtual design module is configured to design the injection molding filling process of the target injection mold based on the rendering model and the formation cause.

[0099] Preferably, before determining the first and second gating channels for forming the weld line during the injection molding process, the data processing module is further configured to: determine whether a weld line occurs during the injection molding process based on flow position data; and determine the first and second gating channels for forming the weld line during the injection molding process, including: if a weld line occurs during the injection molding process, determining the first and second merging grid units for forming the weld line; and determining the first gating channel through which the melt flows to the first merging grid unit and the second merging grid unit. The second pouring channel of the grid cell; determining the integral value of the temperature difference between the first pouring channel and the second pouring channel based on temperature distribution data, including: summing the temperature values ​​of multiple grid cells on the first pouring channel at multiple moments based on the temperature sequence data to obtain the first temperature sum sequence data of the first pouring channel; summing the temperature values ​​of multiple grid cells on the second pouring channel at multiple moments based on the temperature sequence data to obtain the second temperature sum sequence data of the second pouring channel; and determining the integral value of the temperature difference between the first temperature sum sequence data and the second temperature sum sequence data.

[0100] Preferably, the causes include path thermal memory conflict and molecular orientation conflict; the virtual design module is also used to: determine the gate of the melt into the target injection mold according to the rendering model when the cause is path thermal memory conflict; and determine the pouring speed sequence data of the melt into the target injection mold according to the rendering model when the cause is molecular orientation conflict.

[0101] Preferably, determining whether a weld line appears during the injection molding process based on flow position data includes: determining whether there are multiple independent melt flow fronts in the melt based on the flow position data; if multiple independent melt flow fronts are identified, then the area where at least two of the multiple independent melt flow fronts intersect is determined as the intersection area; if the intersection area exists, then it is determined that a weld line appears in the intersection area during the injection molding process; if a weld line appears during the injection molding process, then the first merging grid unit and the second merging grid unit forming the weld line are determined, including: the grid units that the first melt flow front and the second melt flow front that form the weld line come into contact with at the moment of intersection are respectively determined as the first merging grid unit and the second merging grid unit.

[0102] Preferably, the data acquisition module is further used to acquire the original gate of the injection molding filling process; determine the first gating channel where the melt flows to the first merging grid unit and the second gating channel where the melt flows to the second merging grid unit, including: starting from the first merging grid unit, iteratively searching adjacent grid units along the backflow direction of the melt until the original gate to obtain a first search path; starting from the second merging grid unit, iteratively searching adjacent grid units along the backflow direction of the melt until the original gate to obtain a second search path; determining the set of multiple grid units on the first search path as the first gating channel; and determining the set of multiple grid units on the second search path as the second gating channel.

[0103] The cause of the weld line is determined based on the integral value of the temperature difference, including: if the integral value of the temperature difference is greater than the preset integral threshold of the temperature difference, the cause is determined to be path thermal memory conflict; if the integral value of the temperature difference is less than or equal to the preset integral threshold of the temperature difference, the cause is determined to be molecular orientation conflict.

[0104] Preferably, when the cause of formation is path thermal memory conflict, determining the gate for the melt to enter the target injection mold according to the rendering model includes: if the cause of formation is path thermal memory conflict, determining the concentrated area of ​​the first thermal grid unit in the rendering model; determining the center coordinates of the spatial geometric center points between multiple first thermal grid units in the concentrated area in the first coordinate system of the rendering model; obtaining the gate position coordinates of the original gate in the second coordinate system of the target injection mold; transforming the center coordinates in the first coordinate system to the second coordinate system to obtain the center position coordinates; determining the vector direction from the center position coordinates to the gate position coordinates as the offset direction; determining the first theoretical flow length of the first gating channel and the second theoretical flow length of the second gating channel; determining the basic offset based on the difference between the first theoretical flow length and the second theoretical flow length; and moving the original gate along the offset direction according to the basic offset to obtain the gate for the melt to enter the target injection mold.

[0105] Preferably, when the cause is molecular orientation conflict, the pouring speed sequence data of the melt into the target injection mold is determined according to the rendering model, including: acquiring the injection speed curve of the injection speed changing with time during the current injection filling process; determining multiple grid cells occupied by the weld line in the rendering model; determining multiple time data when the multiple second heat grid cells occupied by the weld line begin to be filled by the melt; determining the filling period based on the multiple time data when the multiple second heat grid cells occupied by the weld line begin to be filled by the melt; determining the injection speed curve segment corresponding to the filling period from the injection speed curve; determining the speed fluctuation amplitude in the injection speed curve segment; suppressing the speed fluctuation amplitude according to a preset suppression ratio to obtain the pouring speed curve segment; replacing the injection speed curve segment in the injection speed curve with the pouring speed curve segment to obtain the pouring speed curve.

[0106] Preferably, the first temperature summation sequence data of the first pouring channel is obtained by summing the temperature values ​​of multiple grid cells on the first pouring channel based on multiple moments of the temperature sequence data, including: determining a first summation start time from multiple filling start times when each grid cell on the first pouring channel begins to be filled by melt; determining the formation time of the weld line as the summation end time; determining multiple first reference times between the first summation start time and the summation end time according to the time step; and summing the temperature values ​​of multiple grid cells on the first pouring channel based on the multiple first reference times. The process involves obtaining a first temperature summation sequence data; summing the temperature values ​​of multiple grid cells on the second pouring channel based on multiple moments in the temperature sequence data to obtain a second temperature summation sequence data for the second pouring channel, including: determining a second summation start time from multiple filling start times when each grid cell on the second pouring channel begins to be filled by melt; determining multiple second reference times between the second summation start time and the summation end time based on the time step; and summing the temperature values ​​of multiple grid cells on the second pouring channel based on the multiple second reference times to obtain the second temperature summation sequence data.

[0107] Preferably, determining the integral value of the temperature difference between the first and second pouring channels based on temperature distribution data includes: determining the grid cell with the largest cumulative heat value in the first pouring channel as the first representative cell; determining the grid cell with the largest cumulative heat value in the second pouring channel as the second representative cell; and determining the integral value of the absolute temperature difference between the temperature sequence data of the first representative cell and the temperature sequence data of the second representative cell at each time point as the integral value of the temperature difference between the first and second pouring channels.

[0108] This invention innovatively proposes using the Thermal Differential Integral Value (TDIV) as a quantitative criterion for the formation of weld lines. TDIV can quantify the degree of asymmetry in the thermal history of two flow paths throughout their entire course, thereby reflecting the cumulative difference in molecular chain mobility. Through in-depth research on the causes of weld line formation, it has been found that they can be divided into two types at the molecular motion level: path thermal memory conflict and molecular orientation conflict.

[0109] Path thermal memory conflict: In flow channels with significant length differences, longer-path melts experience longer flow times and / or more cooling, resulting in higher average cooling rates, shorter molecular chain relaxation times, and a greater degree of conformational "freezing." This can even lead to supercooling or localized crystallization, significantly reducing the mobility (diffusion capacity) of the molecular chains. When these less mobile molecular chains intersect with more mobile melt molecular chains from shorter paths, sufficient interdiffusion and entanglement are difficult to achieve, leading to insufficient intermolecular bonding at the melt interface and the formation of weld lines.

[0110] Molecular orientation conflict: Due to differences in inlet pressure between the two flow channels, local cross-sectional changes, or inconsistent injection speed settings / fluctuations, the two melt fronts exhibit significantly different instantaneous flow velocities (huge differences in shear rates) at the junction, or one melt stream may perpendicularly impact the sidewall of the other. This results in a drastic shear rate abrupt change or an extreme flow field (such as stretching flow) at the junction, where polymer chains are highly oriented along the flow direction under strong shear or stretching flow fields. When two melt streams with drastically different orientations or conflicting orientations meet, the molecular chains cannot quickly coordinate and relax to a compatible state. The discontinuity in orientation at the interface hinders effective interpenetration and entanglement, thus forming a weld line.

[0111] To address these two conflict mechanisms, this invention provides a visualization virtual design system for injection molds, which can accurately distinguish the causes of weld lines and make targeted mold designs or process parameter adjustments accordingly.

[0112] This system consists of the following core modules:

[0113] The data acquisition module is responsible for acquiring flow position data and temperature distribution data of the simulated melt flowing into the target injection mold during the injection filling process. Flow position data includes the leading edge position data of the melt as it flows over time, specifically obtained through CAE software simulation. It records the leading edge position information of the melt at each time step (e.g., 0.1 seconds), covering three-dimensional spatial coordinates (x, y, z) and the corresponding timestamp. For example, when simulating the injection molding of a complex plastic shell, it can record the process from the gate, where the melt leading edge gradually expands to the entire cavity over time. The leading edge position at each time point is composed of a large number of grid cells, each with a unique identifier and spatial location information. Temperature distribution data includes the temperature sequence data of each grid cell corresponding to the target injection mold, recorded according to a preset time step (e.g., 0.1 seconds). The temperature data is obtained through heat conduction calculations in the CAE simulation, and the temperature value of each grid cell at different time steps is completely recorded. For example, when simulating the injection molding of polypropylene (PP) material, the temperature values ​​of all grid cells in each 0.1-second interval are recorded from the start of melt injection to the end of filling (assuming a total duration of 5 seconds), forming a temperature matrix, where each element corresponds to the temperature of a specific grid cell at a specific time.

[0114] The data processing module undertakes crucial data analysis and causal identification tasks. When a weld line forms during the injection molding process, the module first determines the first and second gating channels that form the weld line. Specifically, it determines whether multiple independent melt flow fronts exist based on flow position data. If so, it identifies the area where at least two of these fronts intersect as the convergence zone, thereby determining the first and second merging grid units that form the weld line, as well as the corresponding gating channels. Taking a dual-gating injection mold as an example, the simulation revealed that two melt fronts converged in the middle of the cavity, forming a weld line. The data processing module analyzes the flow position data to identify the two independent melt flow fronts and determines the grid units they contact at the moment of convergence as the first and second merging grid units, respectively. Then, starting from these two merging grid units, it iteratively searches adjacent grid units along the melt's reverse flow direction until the original gating gate, obtaining the first and second search paths, thus determining the first and second gating channels.

[0115] Next, the temperature difference integral value (TDIV) between the first and second gating channels is determined based on the temperature distribution data. The specific calculation process is as follows: From multiple grid cells on the first gating channel, the filling start time of each grid cell as it begins to be filled by the melt is extracted to determine the first summation start time; the formation time of the weld line is determined as the summation end time; multiple first reference times are determined based on the time step between the first summation start time and the summation end time; the temperature values ​​of multiple grid cells on the first gating channel are summed based on the multiple first reference times to obtain the first temperature summation sequence data. Similarly, the same operation is performed on the second gating channel to obtain the second temperature summation sequence data.

[0116] Furthermore, the grid cell with the largest heat accumulation value in the first gating channel can be selected as the first representative cell, and the grid cell with the largest heat accumulation value in the second gating channel can be selected as the second representative cell. The absolute temperature difference integral value of the temperature sequence data of the first representative cell and the temperature sequence data of the second representative cell at each time point is determined as TDIV.

[0117] For example, during the simulation, the cumulative heat value (i.e., the total heat of the cell from the time it is filled to the end of the filling process) is calculated for all grid cells on the first pouring channel. The grid cell with the largest cumulative heat value is selected as the first representative cell; similarly, the second representative cell is determined. Then, the temperature values ​​of these two representative cells are compared at each time step, their absolute temperature difference is calculated, and the absolute temperature difference over all time steps is integrated to obtain the TDIV value.

[0118] Based on the preset temperature difference integral threshold (taking polypropylene PP as an example, the critical value is 8℃·second), the TDIV value is determined to determine the cause of the weld line formation: if the TDIV is greater than the preset threshold, the cause is determined to be path thermal memory conflict; if the TDIV is less than or equal to the preset threshold, the cause is determined to be molecular orientation conflict.

[0119] The data visualization module transforms complex data into intuitive visual models, facilitating analysis and understanding by technical personnel. Based on the temperature sequence data of each grid cell, the cumulative heat value is determined from the start of melt filling in that grid cell until the end of the injection molding process. According to the magnitude of the cumulative heat value, the grid cells are divided into first and second heat grid cells; for example, cells with a cumulative heat value greater than a certain threshold are designated as first heat grid cells, and the rest as second heat grid cells. Then, on the cavity model corresponding to the target injection mold, the positions corresponding to the first and second heat grid cells are rendered using a first color (e.g., red) and a second color (e.g., blue), respectively, to obtain the rendered model.

[0120] For example, in the cavity model, areas with higher heat accumulation values ​​(first heat grid cells) are displayed in red, indicating that the melt in that area has experienced more heat, which may correspond to a longer flow path or more cooling; areas with lower heat accumulation values ​​(second heat grid cells) are displayed in blue, indicating that less heat has been experienced. This intuitive color rendering helps technicians quickly locate key areas and analyze the thermal history distribution.

[0121] The virtual design module, based on the formation cause of weld lines and the rendering model, performs targeted design for the injection filling process of the target injection mold. When the formation cause is path thermal memory conflict: the concentrated area of ​​the first thermal grid cell is determined in the rendering model, which usually corresponds to the area of ​​a longer flow path; the center coordinates of the spatial geometric center points between multiple first thermal grid cells in this concentrated area are calculated in the first coordinate system of the rendering model; the gate position coordinates of the original gate in the second coordinate system of the target injection mold are obtained; the center coordinates in the first coordinate system are transformed to the second coordinate system to obtain the center position coordinates; the directional relationship between the original gate and the center position coordinates is determined as the offset direction; simultaneously, the first theoretical flow length of the first gating channel and the second theoretical flow length of the second gating channel are determined, and the basic offset is determined based on the difference between the two; finally, the original gate is moved along the offset direction according to the basic offset to obtain the optimized gate position.

[0122] For example, if the theoretical flow length of the first gating runner is 100mm and the second gating runner is 80mm, the difference is 20mm. If the base offset is set to 1mm for every 10mm difference, then the base offset is 2mm. If the center position coordinates are located directly in front of the original gate in the second coordinate system, then the original gate is moved 2mm in this direction to obtain a new gate position, thereby shortening the length of the longer runner and reducing the difference in thermal history along the path.

[0123] When the cause is molecular orientation conflict: Obtain the injection speed curve of the injection speed changing with time during the current injection molding filling process; determine the multiple grid cells occupied by the weld line in the rendering model; extract multiple time data of when these grid cells begin to be filled by the melt to determine the filling period; find the injection speed curve segment corresponding to the filling period from the injection speed curve; calculate the speed fluctuation amplitude in the segment; suppress the speed fluctuation amplitude according to the preset suppression ratio (such as suppressing 50% of the fluctuation amplitude) to obtain the pouring speed curve segment; finally, replace the corresponding segment in the original injection speed curve with the pouring speed curve segment to obtain the optimized pouring speed curve.

[0124] For example, the original injection rate curve exhibited significant fluctuations during the filling phase, with an amplitude of ±20 mm / s. Analysis of the rendering model identified the critical region for weld line formation during this phase. By suppressing the fluctuations to ±10 mm / s using a preset suppression ratio of 50%, a new injection rate curve segment was generated and replaced with the original segment. This resulted in a more stable melt flow rate in the junction zone, reducing abrupt shear rate changes and mitigating molecular orientation conflicts.

[0125] The steps in the entire technical solution are closely linked, forming a complete workflow:

[0126] 1. The data acquisition module first acquires the flow position data and temperature distribution data of the simulated melt flowing into the target injection mold during the injection filling process, providing basic data support for subsequent analysis.

[0127] 2. Based on the acquired data, the data processing module determines whether a weld line exists. If a weld line exists, it identifies the first and second pouring channels that form the weld line and calculates the temperature difference integral value (TDIV). Based on the comparison between the TDIV and a preset threshold, it accurately determines the cause of the weld line formation (path thermal memory conflict or molecular orientation conflict).

[0128] 3. The data visualization module transforms complex temperature distribution and heat accumulation data into an intuitive rendering model. It displays the heat accumulation in different areas through color differences, providing technical personnel with a visual basis to facilitate subsequent targeted design.

[0129] 4. The virtual design module optimizes the mold gate position or pouring speed based on the formation cause of weld lines and the visualization model. When the conflict is due to path thermal memory, the gate position is adjusted to shorten the runner length difference and optimize the thermal history balance of the flow path. When the conflict is due to molecular orientation, the pouring speed curve is optimized to reduce the sudden change in shear rate in the intersection zone and improve the dynamic characteristics of the flow field.

[0130] The entire process is interconnected, from data collection to problem diagnosis, then to visualization and final optimization design, forming an organic whole. It effectively solves the problems of inaccurate detection of weld line defects, unclear cause analysis, and lack of targeted optimization adjustments in existing technologies.

[0131] Compared with existing technologies, this invention overcomes the limitations of traditional instantaneous temperature difference detection by introducing Temperature Difference Integral Value (TDIV) as a quantitative criterion. This comprehensively considers the cumulative thermal history effect of the melt flowing from the gate to the junction point, accurately reflecting the cumulative differences in molecular chain mobility and enabling more scientific prediction of weld line formation risk. In terms of causal analysis, it deeply analyzes the molecular motion mechanism of weld line formation, clearly distinguishing between path thermal memory conflict and molecular orientation conflict, and establishing corresponding quantitative criteria. This allows technicians to accurately determine the specific causes of weld lines, providing a reliable basis for subsequent targeted optimization and avoiding blind adjustments due to unclear causes in traditional technologies. In terms of optimization design, it precisely optimizes different causal types from two levels: mold structure (gate position adjustment) and process parameters (pouring speed optimization). Through data-driven virtual design, intelligent adjustment of mold design schemes and process parameters is achieved, effectively improving optimization efficiency and success rate, and reducing mold correction time and costs.

[0132] Furthermore, this invention uses a data visualization module to visually display complex thermal history data, greatly enhancing technicians' understanding and analysis capabilities of melt flow and heat transfer processes, and further strengthening the scientific rigor and effectiveness of optimization design.

[0133] Through extensive experimental verification and simulation analysis, the technical solution of this invention has demonstrated remarkable effectiveness. For example, in a case of injection molding of a plastic casing, traditional techniques, unable to accurately determine the cause of weld lines, still resulted in significant weld line defects despite multiple mold modifications and process adjustments, leading to a product defect rate as high as 15%. After applying the system of this invention, the calculated TDIV value was 10°C·s (greater than the critical value of 8°C·s for polypropylene), clearly indicating that path thermal memory conflict was the dominant factor. Based on this, after optimizing the gate position, the weld line defect was significantly improved, and the product defect rate was reduced to below 3%. In another case of injection molding of electronic components, the TDIV value was 6°C·s (less than the critical value), indicating that molecular orientation conflict was the dominant factor. By optimizing the pouring speed curve, the flow rates of the two melt streams in the intersection zone were better matched, the sudden change in shear rate was effectively suppressed, the weld line defect was significantly alleviated, the product surface quality was greatly improved, and the defect rate was reduced from 12% to 2%. These real-world examples fully demonstrate the effectiveness and superiority of the technical solution of this invention, which can accurately diagnose the causes of weld lines in different injection molding scenarios and implement targeted optimization measures, significantly improving product quality and production efficiency.

[0134] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0135] 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. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A visualization virtual design system for injection molds, characterized in that, include: The data acquisition module is used to acquire flow position data and temperature distribution data during the injection filling process of simulated melt flowing into the target injection mold. The flow position data includes the leading edge position data of the melt as it flows over time, and the temperature distribution data includes the temperature sequence data of each grid cell corresponding to the target injection mold, recorded according to a preset time step. The data processing module is used for: When forming the weld line during the injection molding filling process, a first gating channel and a second gating channel for forming the weld line are determined; The integral value of the temperature difference between the first pouring channel and the second pouring channel is determined based on the temperature distribution data; The cause of the weld line formation is determined based on the integral value of the temperature difference; A virtual design module is used to design the injection filling process of the target injection mold based on the formation cause. Specifically, before determining the first and second gating channels for forming the weld line during the injection molding filling process, the data processing module is further configured to: Determine whether weld lines appear during the injection molding process based on the flow position data; When forming the weld line during the injection molding process, determining the first gating channel and the second gating channel for forming the weld line includes: If a weld line appears during the injection molding process, then the first and second merging grid units that form the weld line are identified. The melt flows into the first gating channel of the first confluence grid unit and the melt flows into the second gating channel of the second confluence grid unit; Determining the integral value of the temperature difference between the first gating channel and the second gating channel based on the temperature distribution data includes: The temperature values ​​of multiple grid cells on the first pouring channel are summed at multiple moments based on the temperature sequence data to obtain the first temperature summation sequence data of the first pouring channel; The second temperature summation sequence data of the second pouring channel is obtained by summing the temperature values ​​of multiple grid cells on the second pouring channel at multiple times based on the temperature sequence data; Determine the integral value of the temperature difference between the first temperature summation sequence data and the second temperature summation sequence data; The causes of formation include path thermal memory conflict and molecular orientation conflict; the virtual design module is also used for: When the cause of formation is the path thermal memory conflict, the gate through which the melt enters the target injection mold is determined according to the rendering model; When the cause of formation is the molecular orientation conflict, the injection speed sequence data of the melt being poured into the target injection mold is determined according to the rendering model; The step of determining the cause of the weld line formation based on the integral value of the temperature difference includes: If the integral value of the temperature difference is greater than the preset integral threshold of the temperature difference, then the cause of the formation is determined to be the path thermal memory conflict. If the integral value of the temperature difference is less than or equal to the preset integral threshold of the temperature difference, then the cause of formation is determined to be the molecular orientation conflict.

2. The system as described in claim 1, characterized in that, The system also includes a data visualization module; the data processing module is further used for: The cumulative heat value during the period from the start of the melt filling of the grid cell to the end of the injection filling process is determined based on the temperature sequence data of each grid cell; The data visualization module is used for: The grid unit is divided into a first heat grid unit and a second heat grid unit according to the magnitude of the accumulated heat value; The positions on the cavity model corresponding to the first heat grid unit and the second heat grid unit of the target injection mold are rendered using the first color and the second color respectively to obtain the rendered model; The virtual design module is used to design the injection filling process of the target injection mold based on the rendering model and the formation reason.

3. The system as described in claim 2, characterized in that, The step of determining whether weld lines occur during the injection molding process based on the flow position data includes: Based on the flow position data, determine whether the melt has multiple independent melt flow fronts; If multiple independent melt flow fronts are identified, the area where at least two of the multiple independent melt flow fronts intersect is defined as the intersection zone; If the junction area exists, it is determined that a weld line appears in the junction area during the injection molding process; If a weld line appears during the injection molding process, the first and second merging mesh units that form the weld line are determined, including: The grid cells that the first melt flow front and the second melt flow front come into contact with at the moment of their intersection are respectively defined as the first merging grid cell and the second merging grid cell.

4. The system as described in claim 3, characterized in that, The data acquisition module is also used to acquire the original gate of the injection molding filling process; determining the first gating channel where the melt flows to the first confluence grid unit and the second gating channel where the melt flows to the second confluence grid unit includes: Starting from the first converging grid cell, the adjacent grid cells are iteratively searched along the backflow direction of the melt until the original gate is reached, thus obtaining the first search path; Starting from the second merging grid cell, the adjacent grid cells are iteratively searched along the backflow direction of the melt until the original gate is reached, thus obtaining the second search path; The set of multiple grid cells on the first search path is defined as the first pouring channel; The set of multiple grid cells on the second search path is defined as the second gating channel.

5. The system as described in claim 4, characterized in that, When the cause of formation is the path thermal memory conflict, determining the gate for the melt to enter the target injection mold based on the rendering model includes: If the cause of formation is the path thermal memory conflict, then the concentrated area of ​​the first thermal grid cell is determined in the rendering model; Determine the center coordinates of the spatial geometric center points among multiple first thermal grid units within the concentrated area in the first coordinate system of the rendered model; Obtain the gate position coordinates of the original gate in the second coordinate system of the target injection mold; Transform the center coordinates in the first coordinate system to the second coordinate system to obtain the center position coordinates; The direction of the vector pointing from the center position coordinates to the gate position coordinates is determined as the offset direction; Determine the first theoretical flow length of the first gating channel and the second theoretical flow length of the second gating channel; The base offset is determined based on the difference between the first theoretical flow length and the second theoretical flow length; The original gate is moved along the offset direction according to the basic offset to obtain the gate through which the melt is poured into the target injection mold.

6. The system as described in claim 5, characterized in that, When the cause of formation is the molecular orientation conflict, the process of determining the pouring speed sequence data of the melt into the target injection mold based on the rendering model includes: Obtain the injection speed curve as a function of time during the current injection molding process; In the rendering model, the multiple mesh cells occupied by the fusion line are determined; Determine multiple time data points at which the multiple second thermal grid cells occupied by the weld line begin to be filled by the melt; The filling period is determined based on multiple time data points showing when the multiple second heat grid cells occupied by the fusion line begin to be filled by the melt; Determine the injection speed curve segment corresponding to the filling time period from the injection speed curve; Determine the velocity fluctuation amplitude in the injection velocity curve segment; The speed fluctuation amplitude is suppressed according to a preset suppression ratio to obtain a pouring speed curve segment; Replace the injection speed curve segment in the injection speed curve with the pouring speed curve segment to obtain the pouring speed curve.

7. The system as described in claim 6, characterized in that, The step of summing the temperature values ​​of multiple grid cells on the first casting channel based on the temperature sequence data at multiple times to obtain the first temperature summation sequence data of the first casting channel includes: The first summation start time is determined from a plurality of filling start times in which each of the plurality of grid cells on the first pouring channel begins to be filled by the melt; The formation time of the fusion line is determined as the end time of the summation; Based on the time step, a plurality of first reference times are determined between the first summation start time and the summation end time; The first temperature sum sequence data is obtained by summing the temperature values ​​of multiple grid cells on the first pouring channel based on the multiple first reference times; The step of summing the temperature values ​​of multiple grid cells on the second casting channel based on the temperature sequence data at multiple times to obtain the second temperature summation sequence data of the second casting channel includes: The second summation start time is determined from a plurality of filling start times in which each of the plurality of grid cells on the second pouring channel begins to be filled by the melt; Based on the time step, a plurality of second reference times are determined between the second summation start time and the summation end time; The second temperature sum sequence data is obtained by summing the temperature values ​​of multiple grid cells on the second pouring channel based on the multiple second reference times.

8. The system as described in claim 1, characterized in that, Determining the integral value of the temperature difference between the first gating channel and the second gating channel based on the temperature distribution data includes: The grid cell with the largest cumulative heat value in the first pouring channel is determined as the first representative cell; The grid cell with the largest cumulative heat value in the second pouring channel is determined as the second representative cell; The absolute temperature difference integral value at each time point between the temperature sequence data of the first representative unit and the temperature sequence data of the second representative unit is determined as the temperature difference integral value between the first pouring channel and the second pouring channel.

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