Bumper foaming forming deformation control method based on artificial intelligence

Abstract

This invention relates to the field of injection molding control technology, and more particularly to an artificial intelligence-based method for controlling the deformation of foamed bumper molding. The method includes determining whether the initial injection pressure exceeds the normal range required to suppress foaming; employing segmented control or predicting whether there is a risk of runaway flow in the foamed melt; adopting corresponding adjustment strategies based on the runaway risk value and the weighting coefficients corresponding to several gates to obtain the injection speed adjustment or reduce the initial mold temperature; calculating and predicting whether there will be material shortage and uneven foaming at the end of the cavity based on the injection speed and weighting coefficients of several gates, and using the material shortage risk to reflect whether the adjustment degree of the initial injection speed and mold temperature is reasonable; determining the degree of foaming of the foamed melt in the inspection mold based on the material shortage risk, or reducing the adjustment range of the initial injection speed or initial mold temperature and adjusting the actual cavity pressure in the mold to compensate for the adjustment range. This invention improves bumper performance through foam molding technology.

Description

Technical Field

[0001] This invention relates to the field of injection molding control technology, and in particular to an artificial intelligence-based method for controlling the deformation during the foaming process of a bumper. Background Technology

[0002] Car bumpers are safety devices that absorb and mitigate external impacts, protecting the front and rear of the vehicle. Previously, car bumpers were primarily made of metal, using steel plates at least 3 mm thick stamped into U-shaped channels, chrome-plated, and riveted or welded to the chassis longitudinal beams, leaving a significant gap between them and the body. With the development of the automotive industry, car bumpers, as an important safety device, have undergone innovation. Today's car bumpers, in addition to maintaining their original protective function, strive for harmony and unity with the vehicle's styling, and are also lightweight. To achieve this, car bumpers are now made of plastic, known as plastic bumpers. Plastic bumpers consist of three parts: an outer panel, a buffer material, and a crossbeam. The outer panel and buffer material are made of plastic, while the crossbeam is made of cold-rolled sheet metal approximately 1.5 mm thick, stamped into a U-shaped channel. The outer panel and buffer material are attached to the crossbeam, which is bolted to the chassis longitudinal beams and can be easily removed. The plastics used in these bumpers are primarily polyester-based and polypropylene-based, manufactured using injection molding. Plastic bumpers offer strength, rigidity, and aesthetic appeal. From a safety perspective, they act as a buffer in the event of a collision, protecting the front and rear of the vehicle. From an aesthetic standpoint, they blend seamlessly with the car body, creating a unified whole and serving as an important component in enhancing the car's exterior design.

[0003] Chinese Patent Publication No. CN106476198A discloses an injection molding process for an automotive bumper assembly. The process includes: using PP+EPDM as the injection molding raw material and talc powder with an ash content of 10-20‰ as filler; using mold shrinkage rate as a reference value for the material shrinkage rate, with an intermediate value of 1.0%. Control of process parameters during injection molding includes using multi-gate sequential injection: the gates are evenly distributed at equal intervals on both the upper and lower surfaces of the bumper, and a maximum limit is set for the injection volume of the gate at the middle position on the upper and lower surfaces; the injection process control includes speed control and pressure control; using a chiller to maintain a constant mold temperature; and dividing the barrel into multiple sections with a higher temperature in the middle and decreasing temperature at both ends. Therefore, the aforementioned injection molding process for the automotive bumper assembly has the following problems:

[0004] After the bumper is foamed and molded, it may deform, resulting in problems such as uneven internal air bubbles and dimensional shrinkage. Summary of the Invention

[0005] To address this, the present invention provides an artificial intelligence-based method for controlling the deformation of foamed bumpers, thereby overcoming the problems of deformation, uneven internal air bubbles, and dimensional shrinkage that may occur after the foaming of bumpers in the prior art.

[0006] To achieve the above objectives, the present invention provides an artificial intelligence-based method for controlling the deformation of bumper foam molding, comprising:

[0007] Polystyrene is used as a base material and is added to an injection molding machine along with chemical foaming agents and additives. The mixture is heated and sheared to obtain a foamed melt.

[0008] The foamed melt is injected into the bumper mold using injection molding, and different initial injection pressures are set according to the bumper areas corresponding to several gates.

[0009] Based on the pressure ratio of the initial injection pressure to the foam suppression pressure at any gate, it is determined whether the initial injection pressure exceeds the normal range required to suppress foaming, and segmented control or prediction is adopted to determine whether there is a risk of runaway flow of the foamed melt.

[0010] Based on the melt density of the foamed melt, the estimated injection speed is predicted at the current initial injection pressure. Based on the estimated injection speed at the current foaming agent content, the runaway risk value of the foamed melt is predicted, and it is determined whether there is a risk of runaway flow.

[0011] Based on the runaway risk value and the weight coefficients corresponding to several gates, corresponding adjustment strategies are adopted to dynamically adjust the initial injection speed to obtain the injection adjustment speed, or to reduce the initial mold temperature.

[0012] Based on the injection speed and weighting coefficient of several gates, it is predicted whether there will be material shortage or uneven foaming at the end of the cavity. The material shortage risk reflects whether the adjustment of the initial injection speed and mold temperature is reasonable.

[0013] Determine the degree of foaming of the foamed melt in the mold based on the risk of material shortage, or reduce the adjustment range of the initial injection speed or initial mold temperature and adjust the actual cavity pressure in the mold to compensate for the adjustment range.

[0014] Determine whether the foaming degree at the inner edge of the mold is insufficient based on the foaming pressure and the rate of change of the foaming pressure, and adjust the initial injection volume of the corresponding gate.

[0015] Furthermore, the process of determining whether the initial injection pressure exceeds the normal range required to inhibit foaming includes:

[0016] If the ratio of the initial injection pressure to the foam suppression pressure at any gate is greater than the first standard ratio, it is determined that the initial injection pressure exceeds the normal range required to suppress foaming, and segmented control is adopted.

[0017] When the ratio of the initial injection pressure to the pressure suppressing foaming at any gate is less than or equal to the first standard ratio and greater than or equal to the second standard ratio, the rationality of setting the initial injection pressure of the corresponding gate is judged, and the risk of runaway flow of the foamed melt is predicted under the set initial injection pressure of the corresponding gate.

[0018] Furthermore, the process of predicting whether there is a risk of liquidity spiraling out of control includes:

[0019] The melt density and apparent viscosity of the foamed melt after adding foaming agent into the injection molding machine are detected to predict the estimated injection speed under the current initial injection pressure.

[0020] Based on the estimated injection speed at the current foaming agent content, the runaway risk value is predicted. When the runaway risk value is less than or equal to the critical risk value, it is predicted that there is no risk of runaway flow.

[0021] When the risk of loss of control exceeds the critical risk value, it is predicted that there is a risk of loss of control over liquidity, and corresponding adjustment strategies are adopted according to the weight coefficient corresponding to the gate.

[0022] Furthermore, the corresponding weighting coefficient of the gate is calculated based on the cross-sectional area of ​​the gate and the distance between the gate and the end of the cavity.

[0023] Furthermore, the process of adopting corresponding regulatory strategies includes:

[0024] When the weight coefficient corresponding to the gate is less than or equal to the standard coefficient, the opening of the proportional valve set for the corresponding gate is reduced according to the runaway risk value, thereby reducing the initial injection speed of the gate. The adjusted initial injection speed is the injection adjustment speed.

[0025] When the weighting coefficient corresponding to the gate is greater than the standard coefficient, the initial mold temperature of the mold area corresponding to the gate is reduced according to the ratio of the critical risk value to the runaway risk value.

[0026] Furthermore, the process of predicting whether there will be insufficient material or uneven foaming at the end of the cavity includes:

[0027] When performing foamed melt injection molding, the material shortage risk value is calculated based on the weight coefficient of the injection area corresponding to the gate, the actual melt temperature detected in real time in the mold, and the pressure difference at the gate end to predict whether there will be material shortage or uneven foaming at the end of the cavity.

[0028] Furthermore, when the material shortage risk value is less than or equal to the first standard risk value, it is determined that there is no material shortage risk when the foamed melt is injected according to the adjusted initial injection speed or initial mold temperature;

[0029] When the material shortage risk value is greater than the first standard risk value and less than the second standard risk value, it is determined that the degree of foaming of the foamed melt in the mold needs to be checked when the foamed melt is injected according to the adjusted initial injection speed or initial mold temperature.

[0030] When the material shortage risk value is greater than or equal to the second standard risk value, it is determined that there is a material shortage risk when performing foamed melt injection molding according to the adjusted initial injection speed or initial mold temperature.

[0031] Furthermore, when it is determined that there is a risk of material shortage during foamed melt injection molding, the adjustment range of the initial injection speed or the initial mold temperature is reduced according to the ratio of the first standard risk value to the material shortage risk value. At the same time, the actual cavity pressure in the mold is reduced through the pressure relief port of the cavity according to the reduction ratio of the adjustment range.

[0032] Furthermore, the process of inspecting the degree of foaming of the foamed melt inside the mold includes detecting the foaming pressure using a strain sensor installed inside the mold;

[0033] When the actual difference between the foaming pressure and the standard pressure is less than or equal to the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold meets the molding requirements, and pressure holding and curing are carried out.

[0034] When the actual difference between the foaming pressure and the standard pressure is greater than the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold does not meet the molding requirements. The foaming process of the foamed melt is determined according to the rate of change of the foaming pressure at the edge of the mold.

[0035] Furthermore, when the rate of change of foaming pressure is greater than or equal to the critical rate, it is determined that the inner edge of the mold is in the foaming process, and the foaming pressure is monitored further.

[0036] When the rate of change of foaming pressure is less than the critical rate, it is determined that the degree of foaming at the inner edge of the mold is insufficient, and the initial injection volume of the corresponding gate is increased.

[0037] Compared with existing technologies, the advantages of this invention lie in the fact that the bumper foam molding technology adopts a microporous foaming process to form a sandwich structure of "dense skin layer + foamed core layer + dense skin layer". The process advantages include low density of the foamed material reducing component weight, excellent cushioning performance improving collision safety, the ability to mold complex structures, reduced material usage, and reduced mold wear. However, due to the shape changes caused by the foaming melt, foam deformation control is necessary during the foam molding process of the bumper injection molding.

[0038] Furthermore, the initial injection pressure and the size complexity of the bumper area to be filled by the corresponding gate are related to the viscosity of the foamed melt. The foamed melt needs sufficient pressure (usually 50-150MPa) to resist the flow channel friction resistance (proportional to the melt viscosity η) and the back pressure of the vent at the end of the cavity. Injection pressure, which needs to meet the complexity requirements of the injection mold cavity, is generally much greater than the pressure required to suppress foaming. However, if the injection pressure (e.g., 150 MPa) is directly selected as the injection pressure, it far exceeds the requirement for suppressing foaming (only 12 bar is needed), leading to excessive suppression and insufficient foaming (high density), which conflicts with the goal of making the bumper as light as possible. Moreover, excessively high pressure may cause melt shear overheating (a sudden drop in viscosity leading to uncontrolled flow), which can cause asymmetric deformation. This method judges the rationality of the initial injection pressure setting of the corresponding gate by the pressure ratio of the initial injection pressure of any gate to the pressure required to suppress foaming, determines whether the initial injection pressure exceeds the normal range required to suppress foaming, and optimizes the degree to which the injection pressure exceeds the pressure required to suppress foaming. Subsequently, corresponding measures are taken to control the deformation of the foamed bumper based on the degree of foam suppression.

[0039] Furthermore, in the application scenario of this embodiment, the conflict point in the foam molding of the bumper lies in the fact that higher complexity or weighting coefficients require higher pressure, but higher pressure inhibits foaming. At the same time, the complexity of the injection areas corresponding to the various gates of the bumper varies. This method predicts the injection speed by combining the current initial injection pressure with the melt flow resistance to determine whether local temperature rise will occur due to shear heat generation. Since changing the mold temperature affects the degree of foaming, the injection pressure / speed and the degree of foaming need to work together to meet the complexity requirements of different gates. Therefore, this method reacts to the complexity based on the degree of runaway risk and the weighting coefficient of the bumper. According to the weighting coefficient corresponding to the gate, it adopts the corresponding adjustment strategy to determine whether to adjust the injection speed or adjust the initial mold temperature to reduce fluidity. At the same time, reducing the injection speed will affect the injection efficiency. Therefore, this method determines the adjustment strategy according to the complexity. When the complexity is high, the injection speed is adjusted by increasing the valve opening while keeping the injection pressure constant. When the complexity is low, the mold temperature is adjusted first to reduce fluidity and avoid runaway fluidity. This increases the flexibility of the adjustment strategy when there is a risk of runaway fluidity in the foamed melt and reduces the impact of the injection pressure inhibiting the foaming pressure on the control of the bumper foam molding.

[0040] Furthermore, this method reflects the different complexities of different injection parts of the bumper by using the corresponding weight coefficients of several injection areas of the bumper, and calculates the material shortage risk value (SRI) based on several injection parameters of the foamed melt to determine whether there will be material shortage at the end of the cavity during the foamed melt injection after adjustment. The material shortage risk reflects whether the previous adjustment of the injection speed and mold temperature is reasonable. When there is a material shortage risk, the adjustment of the injection speed and mold temperature is reduced according to the magnitude of the material shortage risk. In addition, the actual cavity pressure in the mold is reduced through the pressure relief port of the cavity to promote foaming to compensate for the reduced adjustment amount. This improves the flexibility and adaptability of detecting and adjusting the deformation control of the bumper foaming molding according to the complexity of different areas.

[0041] Furthermore, since the foaming ratio in areas far from the gate (1.8 times) may be 50% higher than that near the gate (1.2 times), the more complex the injection area, the more difficult it is to achieve uniform foaming. In this method, when the predicted material shortage risk reflects the reasonableness of the previous adjustments to injection speed and mold temperature, and the reasonableness of the predicted material shortage risk value is unclear, the foaming pressure is used to determine whether the foaming degree of the melt in the mold meets the molding requirements, and to determine the timing of pressure holding and curing. Furthermore, the rate of change of foaming pressure is used to verify the edge foaming degree to determine whether the melt is still foaming, avoiding misjudgment of the foaming degree of the melt in the mold. When the edge foaming degree in the mold is insufficient, the initial injection volume of the corresponding gate is supplemented accordingly, increasing the injection volume in the corresponding area for dynamic foaming control. This improves the adaptability and accuracy of judging the reasonableness of the adjustments to injection speed and mold temperature during bumper foaming molding deformation control, thus enabling compensatory adjustments. Attached Figure Description

[0042] Figure 1 This is a flowchart illustrating the artificial intelligence-based deformation control method for bumper foaming molding in an embodiment of the present invention.

[0043] Figure 2 This is a schematic diagram of the bumper structure in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the process for determining whether the initial injection pressure exceeds the normal range required to inhibit foaming in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram illustrating the process for determining whether there is a risk of liquidity spiraling out of control in an embodiment of the present invention;

[0046] In the picture: 1-Bumper, 2-Injection port. Detailed Implementation

[0047] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0048] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0049] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0050] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] Please see Figures 1-4 As shown, Figure 1 This is a flowchart illustrating the artificial intelligence-based deformation control method for bumper foaming molding in an embodiment of the present invention. Figure 2 This is a schematic diagram of the bumper structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the process for determining whether the initial injection pressure exceeds the normal range required to inhibit foaming in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the process for determining whether there is a risk of liquidity spiraling out of control in an embodiment of the present invention.

[0052] This invention provides an artificial intelligence-based method for controlling the deformation during the foaming process of a bumper, comprising:

[0053] Step S1: Polystyrene, as the base material, is added to an injection molding machine along with chemical foaming agents and additives, and heated and sheared to obtain foamed melt;

[0054] Step S2: The foamed melt is injected into the bumper mold using injection molding, and different initial injection pressures are set according to the bumper areas corresponding to several gates.

[0055] Step S3: Determine whether the initial injection pressure exceeds the normal range required to suppress foaming based on the pressure ratio of the initial injection pressure to the foaming suppression pressure at any gate, and use segmented control or predict whether there is a risk of runaway flow of the foamed melt.

[0056] Step S4: Based on the melt density of the foamed melt, predict the estimated injection speed at the current initial injection pressure; based on the estimated injection speed at the current foaming agent content, predict the runaway risk value of the foamed melt; and determine whether there is a risk of runaway flow.

[0057] Step S5: Based on the runaway risk value and the weighting coefficients corresponding to several gates, adopt corresponding adjustment strategies to dynamically adjust the initial injection speed to obtain the injection adjustment speed or reduce the initial mold temperature.

[0058] Step S6: When injecting foamed melt after adjusting the initial injection speed or initial mold temperature, calculate and predict whether there will be material shortage or uneven foaming at the end of the cavity based on the injection speed and weight coefficient of several gates, check the degree of foaming of the foamed melt in the mold, or reduce the adjustment range of the initial injection speed or initial mold temperature.

[0059] Step S7: Determine whether the foaming degree at the inner edge of the mold is insufficient based on the foaming pressure and the rate of change of the foaming pressure, and adjust the initial injection volume of the corresponding gate.

[0060] In this embodiment, polystyrene (EPP) is used as the foaming material, and a chemical foaming agent is used as the foaming agent. Polymers such as polystyrene (EPP) are used as the base material, and chemical foaming agents (such as azodicarbonamide) and other additives are added.

[0061] like Figure 2 As shown in the figure, the dotted lines divide the bumper into 5 injection molding areas, each corresponding to a gate, and the injection molding areas have different complexity levels.

[0062] After adding a chemical foaming agent, heating and stirring cause the foaming agent to release gas, and the material expands to form a microporous structure.

[0063] The foaming timing of the foamed melt is during or after injection molding, and the initial foaming occurs. Before injection molding, the chemical foaming agent (such as AC foaming agent) is mixed into the polystyrene (EPP) raw material in granular form and has not decomposed. During injection molding, the high temperature of the barrel (170-200℃) causes the foaming agent to decompose and release gas (N2 / CO2), but the high pressure inhibits foaming. After injection molding, the pressure decreases after the melt enters the mold cavity, and the gas expands and foams (continues until the initial cooling stage).

[0064] Unfoamed foamed melt is injected into a mold through injection molding. The molded part is shaped into the required shape by controlling the pressure and temperature. The molded part needs to be cooled and solidified to maintain its shape and structure.

[0065] Specifically, the bumper foam molding technology employs a microporous foaming process to form a sandwich structure of "dense skin layer + foamed core layer + dense skin layer". The advantages of this process include low foam material density reducing component weight, excellent cushioning performance improving collision safety, the ability to mold complex structures, reduced material usage, and lower mold wear. However, due to the shape changes caused by the foaming melt, foam deformation control is necessary during the bumper injection molding process.

[0066] In this embodiment, multi-gate sequential injection is used, with 5 gates distributed on the top of the bumper, and the bumper has an asymmetrical structure.

[0067] In practice, due to the different complexities of the injection areas of the bumpers corresponding to the various gates, the initial injection pressures of the various gates are set differently.

[0068] Specifically, the injection areas corresponding to several gates are divided into three complexity levels according to weighting coefficients, including first complexity, second complexity and third complexity;

[0069] The first gate has the first complexity, the second and third gates have the second complexity, and the fourth and fifth gates have the third complexity.

[0070] In practice, the first complexity is less than the second complexity, which is less than the third complexity.

[0071] Set the initial injection pressure corresponding to several gates, and determine the foaming suppression pressure according to the foaming agent content added to the foamed melt;

[0072] If the ratio of the initial injection pressure to the foam suppression pressure at any gate is greater than the first standard ratio, it is determined that the initial injection pressure exceeds the normal range required to suppress foaming, and segmented control is adopted.

[0073] Specifically, the segmented control is divided into two stages: Stage 1 (90% filling) uses high pressure and high speed (e.g., 120MPa, 200mm / s) to ensure filling; Stage 2 (end) uses reduced pressure and speed (e.g., 80MPa, 50mm / s) to promote foaming.

[0074] When the ratio of the initial injection pressure to the pressure suppressing foaming at any gate is less than or equal to the first standard ratio and greater than or equal to the second standard ratio, the rationality of setting the initial injection pressure of the corresponding gate is judged, and the risk of runaway flow of the foamed melt is predicted under the set initial injection pressure of the corresponding gate.

[0075] If the ratio of the initial injection pressure to the foam suppression pressure at any gate is less than the second standard ratio, it is determined that the initial injection pressure has not exceeded the normal range required to suppress foaming, and multi-gate sequential injection is performed.

[0076] Wherein, the first standard ratio and the second standard ratio are preset values ​​set based on the historical data of the suppressed foaming pressure.

[0077] Specifically, the initial injection pressure is related to the size complexity of the bumper area to be filled by the corresponding gate and the viscosity of the foamed melt. The foamed melt needs sufficient pressure (usually 50-150MPa) to resist the flow channel friction resistance (proportional to the melt viscosity η) and the back pressure of the vent at the end of the cavity. Injection pressure, which needs to meet the complexity requirements of the injection mold cavity, is generally much greater than the pressure required to suppress foaming. However, if the injection pressure (e.g., 150 MPa) is directly selected as the injection pressure, it far exceeds the requirement for suppressing foaming (only 12 bar is needed), leading to excessive suppression and insufficient foaming (high density), which conflicts with the goal of making the bumper as light as possible. Moreover, excessively high pressure may cause melt shear overheating (a sudden drop in viscosity leading to uncontrolled flow), which can cause asymmetric deformation. This method judges the rationality of the initial injection pressure setting of the corresponding gate by the pressure ratio of the initial injection pressure of any gate to the pressure required to suppress foaming, determines whether the initial injection pressure exceeds the normal range required to suppress foaming, and optimizes the degree to which the injection pressure exceeds the pressure required to suppress foaming. Subsequently, corresponding measures are taken to control the deformation of the foamed bumper based on the degree of foam suppression.

[0078] The injection speed is determined by the initial injection pressure, melt flow resistance, and runner radius and length. The opening of the proportional valve can adjust the injection speed.

[0079] The melt density and apparent viscosity of the foamed melt after adding foaming agent in the injection molding machine are detected to predict the estimated injection speed under the current initial injection pressure.

[0080] Estimated injection speed = In the formula, P is the initial injection pressure, ρ is the melt density, R is the flow channel radius, L is the flow channel length, and η is the melt apparent viscosity.

[0081] Predict the runaway risk value R based on the estimated injection speed at the current foaming agent content, and control the flow front balance;

[0082] The flow index Fi = Vi - Va for the i-th gate, and the flow balance index Fc is the absolute value of the maximum difference between the estimated injection speed Vi of the i-th gate and the average speed Va of the estimated injection speed of all gates. The flow balance index Fc = max(|Vi ​​- Va|).

[0083] The runaway risk value R is predicted based on historical melt temperatures and estimated injection speeds. In the formula, Tm is the historical melt temperature, and Pi is the initial injection pressure of the i-th gate;

[0084] When the risk value R is less than or equal to the critical risk value, it is predicted that there is no risk of liquidity running out of control.

[0085] When the risk value R of out-of-control is greater than the critical risk value, it is predicted that there is a risk of out-of-control liquidity, and corresponding adjustment strategies are adopted according to the weight coefficient of the gate.

[0086] Considering the weight of the gate's influence on the flow, which is related to the gate's cross-sectional area Ai and the distance Li to the end of the cavity, the corresponding weight coefficient Wi of the gate is calculated.

[0087] The weighting coefficient corresponding to the i-th gate The corresponding average weighting coefficient is calculated. ;

[0088] When the weighting coefficient corresponding to the i-th gate is less than or equal to the standard coefficient, the initial injection speed of the i-th gate is reduced according to the runaway risk value R, and the injection speed is dynamically adjusted. ;

[0089] Specifically, the initial injection speed is reduced by decreasing the opening of the proportional valve set at the corresponding gate;

[0090] When the weight coefficient corresponding to the i-th gate is greater than the standard coefficient, the initial mold temperature of the mold area corresponding to the i-th gate is reduced according to the ratio of the critical risk value to the runaway risk value R.

[0091] The critical risk value is 20, and the standard coefficient is 0.5.

[0092] Specifically, in the application scenario of this embodiment, the conflict in bumper foam molding lies in the fact that higher complexity or weighting coefficients require higher pressure, but higher pressure inhibits foaming. Furthermore, the complexity of the injection areas corresponding to the various gates of the bumper varies. This method predicts the injection speed by combining the current initial injection pressure with melt flow resistance to determine whether local temperature rise will occur due to shear heat. Since changing the mold temperature affects the degree of foaming, the injection pressure / speed and the degree of foaming need to work together to meet the complexity requirements of different gates. Therefore, this method considers the degree of runaway risk in conjunction with the weighting coefficient of the bumper to reflect complexity. Based on the weighting coefficient corresponding to the gate, it adopts corresponding adjustment strategies to determine whether to adjust the injection speed or adjust the initial mold temperature to reduce fluidity. At the same time, reducing the injection speed will affect injection efficiency. Therefore, this method determines the adjustment strategy based on the complexity. When the complexity is high, the injection speed is adjusted by increasing the valve opening while keeping the injection pressure constant. When the complexity is low, the mold temperature is adjusted first to reduce fluidity and avoid runaway fluidity. This increases the flexibility of the adjustment strategy when there is a risk of runaway fluidity in the foamed melt and reduces the impact of injection pressure inhibiting foaming pressure on the control of bumper foam molding.

[0093] When performing foamed melt injection molding, the weight coefficient of the injection area corresponding to the gate of the bumper, the injection adjustment speed and the mold temperature, as well as the actual melt temperature and the pressure difference at the end of the gate detected in real time in the mold, are used to predict whether there will be a shortage of material or uneven foaming at the end of the cavity.

[0094] In practice, the pressure difference ΔP at the gate end is detected and calculated by pressure sensors installed at the mold gate and the end of the cavity, and the actual mold temperature and the actual melt temperature are detected by temperature sensors installed in the mold.

[0095] Specifically, the risk value of material shortage In the formula, Wi is the weighting coefficient corresponding to the injection area of ​​several gates, Vi1 is the adjusted injection speed, T1 is the actual melt temperature, T2 is the actual mold temperature, ΔP is the pressure difference at the end of the gate, and Pc is the critical flow pressure of the material. In this embodiment, Pc is 80MPa.

[0096] When the material shortage risk value SRI is less than or equal to the first standard risk value, it is determined that there is no material shortage risk when foamed melt is injected according to the adjusted initial injection speed or initial mold temperature.

[0097] When the material shortage risk value SRI is greater than the first standard risk value and less than the second standard risk value, it is determined that the degree of foaming of the foamed melt in the mold needs to be checked when the foamed melt is injected according to the adjusted initial injection speed or initial mold temperature.

[0098] When the material shortage risk value SRI is greater than or equal to the second standard risk value, it is determined that there is a material shortage risk when foamed melt is injected according to the adjusted initial injection speed or initial mold temperature, and the adjustment range of the initial injection speed or initial mold temperature is reduced.

[0099] Specifically, when it is determined that there is a risk of material shortage during foamed melt injection molding, the adjustment range of the initial injection speed or the initial mold temperature is reduced according to the ratio of the first standard risk value to the material shortage risk value SRI, and the actual cavity pressure in the mold is reduced according to the reduction ratio of the adjustment range.

[0100] During implementation, the actual cavity pressure inside the mold is reduced through the pressure relief port of the cavity.

[0101] The first standard risk value is 0.8, and the second standard risk value is 1.5.

[0102] Specifically, this method reflects the different complexities of different injection parts of the bumper by using the corresponding weight coefficients of several injection areas. It also calculates the short-material risk value (SRI) based on several injection parameters of the foamed melt to determine whether there will be a short-material risk at the end of the cavity during the foamed melt injection after adjustment. The short-material risk reflects whether the previous adjustments to the injection speed and mold temperature are reasonable. When there is a short-material risk, the adjustment of the injection speed and mold temperature is reduced according to the magnitude of the short-material risk. Furthermore, the actual cavity pressure in the mold is reduced through the cavity pressure relief port to promote foaming and compensate for the reduced adjustment amount. This improves the flexibility and adaptability of detecting and adjusting the deformation control of the bumper foaming molding according to the complexity of different areas.

[0103] The bumper is injected sequentially through multiple gates. The change in the amount of glue at each gate directly leads to local dimensional fluctuations. Therefore, a limit is set on the amount of glue injected at the gate located in the middle of the upper and lower surfaces.

[0104] The process of inspecting the degree of foaming of the foamed melt in the mold includes:

[0105] After the foamed melt stream is injected according to the adjusted injection speed or initial mold temperature, the foaming pressure is detected by the strain sensor installed in the mold.

[0106] The degree of foaming of the foamed melt in the mold is reflected by the foaming pressure, and whether the injection volume meets the molding requirements is determined by the rate of change of the foaming pressure.

[0107] When the actual difference between the foaming pressure and the standard pressure is less than or equal to the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold meets the molding requirements, and pressure holding and curing are carried out.

[0108] When the actual difference between the foaming pressure and the standard pressure is greater than the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold does not meet the molding requirements. The foaming process of the foamed melt is determined according to the rate of change of the foaming pressure at the edge of the mold.

[0109] Specifically, when the rate of change of foaming pressure is greater than or equal to the critical rate, it is determined that the inner edge of the mold is in the foaming process, and the foaming pressure is monitored.

[0110] When the rate of change of foaming pressure is less than the critical rate, it is determined that the degree of foaming at the inner edge of the mold is insufficient, and the initial injection volume of the corresponding gate is increased.

[0111] The standard pressure is a preset value set based on the historical curing data of the foamed melt, the difference evaluation value is 0.8 MPa, and the critical rate is a preset value set based on the historical data of the rate of change of foaming pressure.

[0112] Specifically, since the foaming ratio in areas far from the gate (1.8 times) may be 50% higher than that near the gate (1.2 times), the more complex the injection area, the more difficult it is to achieve uniform foaming. This method, in the process of reflecting the rationality of the previous adjustments to injection speed and mold temperature through the material shortage risk, when the predicted material shortage risk value is unclear in reflecting rationality, uses foaming pressure to determine whether the foaming degree of the foamed melt in the mold meets the molding requirements, determines the timing of pressure holding and curing, and further verifies the edge foaming degree based on the rate of change of foaming pressure to determine whether the foamed melt is still in the foaming process, avoiding misjudgment of the foaming degree of the foamed melt in the mold. When the foaming degree at the edge of the mold is insufficient, the initial injection volume of the corresponding gate is supplemented accordingly, increasing the injection volume in the corresponding area for dynamic foaming control. This improves the adaptability and accuracy of judging the rationality of the adjustments to injection speed and mold temperature during bumper foaming molding deformation control, thus enabling compensatory adjustments.

[0113] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the deformation during foam molding of a bumper based on artificial intelligence, characterized in that, include: Polystyrene is used as a base material and is added to an injection molding machine along with chemical foaming agents and additives. The mixture is heated and sheared to obtain a foamed melt. The foamed melt is injected into the bumper mold using injection molding, and different initial injection pressures are set according to the bumper areas corresponding to several gates. Based on the pressure ratio of the initial injection pressure to the foam suppression pressure at any gate, it is determined whether the initial injection pressure exceeds the normal range required to suppress foaming, and segmented control or prediction is adopted to determine whether there is a risk of runaway flow of the foamed melt. Based on the melt density of the foamed melt, the estimated injection speed is predicted at the current initial injection pressure. Based on the estimated injection speed at the current foaming agent content, the runaway risk value of the foamed melt is predicted, and it is determined whether there is a risk of runaway flow. Based on the runaway risk value and the weight coefficients corresponding to several gates, corresponding adjustment strategies are adopted to dynamically adjust the initial injection speed to obtain the injection adjustment speed, or to reduce the initial mold temperature. Based on the injection speed and weighting coefficient of several gates, it is predicted whether there will be material shortage or uneven foaming at the end of the cavity. The material shortage risk value reflects whether the adjustment of the initial injection speed and mold temperature is reasonable. The degree of foaming of the foamed melt in the test mold is determined based on the material shortage risk value, or the adjustment range of the initial injection speed or the initial mold temperature is reduced and the adjustment range is compensated by adjusting the actual cavity pressure in the mold. Determine whether the foaming degree at the inner edge of the mold is insufficient based on the foaming pressure and the rate of change of the foaming pressure, and adjust the initial injection volume of the corresponding gate.

2. The artificial intelligence-based bumper foam molding deformation control method according to claim 1, characterized in that, The process of determining whether the initial injection pressure exceeds the normal range required to inhibit foaming includes: If the ratio of the initial injection pressure to the foam suppression pressure at any gate is greater than the first standard ratio, it is determined that the initial injection pressure exceeds the normal range required to suppress foaming, and segmented control is adopted. When the ratio of the initial injection pressure to the pressure suppressing foaming at any gate is less than or equal to the first standard ratio and greater than or equal to the second standard ratio, the rationality of setting the initial injection pressure of the corresponding gate is judged, and the risk of runaway flow of the foamed melt is predicted under the set initial injection pressure of the corresponding gate.

3. The artificial intelligence-based bumper foam molding deformation control method according to claim 2, characterized in that, The process of predicting whether liquidity is at risk of spiraling out of control includes: The melt density and apparent viscosity of the foamed melt after adding foaming agent into the injection molding machine are detected to predict the estimated injection speed under the current initial injection pressure. Based on the estimated injection speed at the current foaming agent content, the runaway risk value is predicted. When the runaway risk value is less than or equal to the critical risk value, it is predicted that there is no risk of runaway flow. When the risk of loss of control exceeds the critical risk value, it is predicted that there is a risk of loss of control over liquidity, and corresponding adjustment strategies are adopted according to the weight coefficient corresponding to the gate.

4. The artificial intelligence-based bumper foam molding deformation control method according to claim 3, characterized in that, The weighting coefficient of the gate is calculated based on the cross-sectional area of ​​the gate and the distance between the gate and the end of the cavity.

5. The artificial intelligence-based bumper foam molding deformation control method according to claim 4, characterized in that, The process of adopting corresponding adjustment strategies includes: When the weight coefficient corresponding to the gate is less than or equal to the standard coefficient, the opening of the proportional valve set for the corresponding gate is reduced according to the runaway risk value, thereby reducing the initial injection speed of the gate. The adjusted initial injection speed is the injection adjustment speed. When the weighting coefficient corresponding to the gate is greater than the standard coefficient, the initial mold temperature of the mold area corresponding to the gate is reduced according to the ratio of the critical risk value to the runaway risk value.

6. The artificial intelligence-based bumper foam molding deformation control method according to claim 5, characterized in that, The process of predicting whether there will be insufficient material or uneven foaming at the end of the cavity includes: When performing foamed melt injection molding, the material shortage risk value is calculated based on the weight coefficient of the injection area corresponding to the gate, the actual melt temperature detected in real time in the mold, and the pressure difference at the gate end to predict whether there will be material shortage or uneven foaming at the end of the cavity.

7. The artificial intelligence-based bumper foam molding deformation control method according to claim 6, characterized in that, When the material shortage risk value is less than or equal to the first standard risk value, it is determined that there is no material shortage risk when foamed melt is injected according to the adjusted initial injection speed or initial mold temperature. When the material shortage risk value is greater than the first standard risk value and less than the second standard risk value, it is determined that the degree of foaming of the foamed melt in the mold needs to be checked when the foamed melt is injected according to the adjusted initial injection speed or initial mold temperature. When the material shortage risk value is greater than or equal to the second standard risk value, it is determined that there is a material shortage risk when performing foamed melt injection molding according to the adjusted initial injection speed or initial mold temperature.

8. The artificial intelligence-based bumper foam molding deformation control method according to claim 7, characterized in that, When it is determined that there is a risk of material shortage during foamed melt injection molding, the adjustment range of the initial injection speed or the initial mold temperature is reduced according to the ratio of the first standard risk value to the material shortage risk value. At the same time, the actual cavity pressure in the mold is reduced through the pressure relief port of the cavity according to the reduction ratio of the adjustment range.

9. The artificial intelligence-based bumper foam molding deformation control method according to claim 8, characterized in that, The process of inspecting the degree of foaming of the foamed melt in the mold includes detecting the foaming pressure using a strain sensor installed inside the mold. When the actual difference between the foaming pressure and the standard pressure is less than or equal to the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold meets the molding requirements, and pressure holding and curing are carried out. When the actual difference between the foaming pressure and the standard pressure is greater than the difference evaluation value, it is determined that the degree of foaming of the foamed melt in the mold does not meet the molding requirements. The foaming process of the foamed melt is determined according to the rate of change of the foaming pressure at the edge of the mold.

10. The artificial intelligence-based bumper foam molding deformation control method according to claim 9, characterized in that, When the rate of change of foaming pressure is greater than or equal to the critical rate, it is determined that the inner edge of the mold is in the foaming process, and the foaming pressure is monitored. When the rate of change of foaming pressure is less than the critical rate, it is determined that the degree of foaming at the inner edge of the mold is insufficient, and the initial injection volume of the corresponding gate is increased.

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