Automotive interior mat forming control method and system

Abstract

The application provides a kind of automobile interior pad forming control method and system, it is related to automobile accessory manufacturing technical field.The method includes the following steps: determining the optimal temperature control curve of hot pressing forming process according to the model of interior pad;In the temperature rising sub-stage, the mold cavity is heated by the main heating module, and the current maximum temperature is obtained according to the actual temperature of several monitoring points in the mold cavity;If the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module is set to constant temperature mode, and the working parameters of the auxiliary heating module are configured according to the maximum temperature and the actual temperature of each monitoring point;After the duration of the main heating module in constant temperature mode reaches the target constant temperature time, enter the next temperature control stage.The application ensures that the overall temperature of the mold cavity quickly reaches the target value and remains stable through the cooperative control of the main heating module and the auxiliary heating module, while eliminating local temperature difference, so as to balance the rapid response and steady precision of temperature in the hot pressing forming process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile accessory manufacturing, in particular to a forming control method and system for automobile interior pad. BACKGROUND

[0002] With the rapid development of the automobile industry, consumers' requirements for the quality of automobile interior parts are increasing, especially the dimensional accuracy, surface finish and forming stability of the interior pad directly affect the comfort and aesthetics of the vehicle. Hot press forming process is the key link to ensure the dimensional accuracy and surface quality of the automobile interior pad. The traditional hot press forming process relies on manual experience to control the temperature, which has low temperature control accuracy and poor forming consistency, and is prone to cause insufficient melting of the material or local overheating, affecting the product yield.

[0003] In recent years, in order to improve the hot press forming quality, the industry has gradually introduced automatic temperature control technology, such as using PID algorithm to adjust the heating power or setting temperature curve in stages, to improve the stability of the forming process. However, these methods still cannot effectively eliminate the local temperature difference in the mold cavity, and lack of dynamic adjustment capability, resulting in difficulty in balancing the rapid response and steady accuracy of the temperature. SUMMARY

[0004] The purpose of the present application is to provide a forming control method and system for automobile interior pad, which ensures that the overall temperature of the mold cavity quickly reaches the target value and remains stable through the cooperative control of the main heating module and the auxiliary heating module, while eliminating the local temperature difference, so as to balance the rapid response and steady accuracy of the temperature in the hot press forming process.

[0005] In the first aspect, the present application provides a forming control method for automobile interior pad, comprising the steps of:

[0006] determining the optimal temperature control curve of the hot press forming process according to the model of the interior pad; the optimal temperature control curve comprises several temperature control stages; the temperature control stage comprises a temperature rising sub-stage and a constant temperature sub-stage; each constant temperature sub-stage is provided with a corresponding target constant temperature and a target constant temperature time;

[0007] In the temperature rising sub-stage, the mold cavity is heated by the main heating module, and the current maximum temperature is obtained according to the actual temperature of the several monitoring points in the mold cavity;

[0008] If the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module is set to constant temperature mode, and the working parameters of the auxiliary heating module are configured according to the maximum temperature and the actual temperature of each monitoring point;

[0009] After the duration of the main heating module in the constant temperature mode reaches the target constant temperature time, the next temperature control stage is entered.

[0010] As a preferred scheme of the present application, the step of determining the optimal temperature control curve of the hot press forming process according to the trim pad model specifically comprises the steps of:

[0011] S101, determining the material thermal parameters of each layer material corresponding to the trim pad model through experiments;

[0012] S102, constructing a test temperature control curve based on the material thermal parameters of each layer material; the test temperature control curve comprises several temperature control stages and corresponding target constant temperature temperatures;

[0013] S103, constructing a three-dimensional model of the trim pad, and setting simulation parameters of the three-dimensional model according to the material thermal parameters;

[0014] S104, simulating the three-dimensional model according to the test temperature control curve to obtain temperature simulation data corresponding to several time points;

[0015] S105, obtaining a temperature standard deviation corresponding to each time point according to the temperature simulation data;

[0016] S106, if the temperature standard deviation is greater than a first uniformity threshold, adjusting the corresponding temperature control stage in the test temperature control curve according to the difference between the temperature standard deviation and the first uniformity threshold, and returning to step S104; otherwise, taking the test temperature control curve as the optimal temperature control curve.

[0017] As a preferred scheme of the present application, the step of adjusting the corresponding temperature control stage in the test temperature control curve specifically comprises the steps of: if the temperature standard deviation exceeds the standard in a temperature rising sub-stage, reducing a target temperature rising rate and prolonging a target temperature rising time; and if the temperature standard deviation exceeds the standard in a constant temperature sub-stage, increasing a target constant temperature and / or prolonging a target constant temperature time.

[0018] As a preferred scheme of the present application, the step of heating the mold cavity by the main heating module comprises the steps of:

[0019] setting a fuzzy control rule;

[0020] calculating a first temperature error and a first error change rate according to the target constant temperature and the maximum current temperature;

[0021] mapping the first temperature error and the first error change rate into a fuzzy set, and determining the output power of the main heating module according to the fuzzy set and the fuzzy control rule.

[0022] As a preferred scheme of the present application, the step of heating the mold cavity by the main heating module comprises the steps of:

[0023] setting a fuzzy control rule of the first temperature rising control mode and an optimization objective function of the second temperature rising control mode;

[0024] Calculate a first temperature error and a first error change rate according to the target constant temperature and the current temperature maximum value;

[0025] Determine a temperature rising control strategy according to the first temperature error and the first error change rate; the temperature rising control strategy comprises a first temperature rising control mode and a second temperature rising control mode;

[0026] The first temperature rising control mode is that the first temperature error and the first error change rate are mapped to a fuzzy set, and the output power of the main heating module is determined according to the fuzzy set and a fuzzy control rule;

[0027] The second temperature rising control mode is that the current temperature maximum value is substituted into an optimization target function, and the output power of the main heating module is obtained by solving.

[0028] As a preferred scheme of the present application, the temperature rising control strategy is determined according to the first temperature error and the first error change rate, specifically, when the first temperature error is greater than a first temperature error threshold or the first error change rate is greater than a first error change rate threshold, the first temperature rising control mode is selected as the temperature rising control strategy; when the first temperature error is less than or equal to the first temperature error threshold and the first error change rate is less than or equal to the first error change rate threshold, the second temperature rising control mode is selected as the temperature rising control strategy.

[0029] As a preferred scheme of the present application, the optimization target function is expressed as:

[0030] ;

[0031] Wherein, represents the target constant temperature, represents a prediction time domain, represents a control time domain, represents an input weight coefficient, represents a power change amount; represents the current temperature maximum value.

[0032] As a preferred scheme of the present application, the working parameters of the auxiliary heating module are configured according to the temperature maximum value and the actual temperatures of the monitoring points, comprising the steps that:

[0033] Real-time calculate a second temperature error of each monitoring point and the temperature maximum value;

[0034] If the second temperature error is greater than an auxiliary heating demand threshold, a second error change rate is calculated according to the difference of the second temperature errors of two adjacent time steps;

[0035] The output power of the auxiliary heating module is configured according to the second temperature error.

[0036] As a preferred scheme of the present application, the output power of the auxiliary heating module is expressed as:

[0037] ;

[0038] wherein, represents the output power of the i-th electric heating element of the auxiliary heating module; represents the second temperature error of the i-th monitoring point; is an error gain coefficient; is a differential gain; i is the number of monitoring points and electric heating elements.

[0039] In a second aspect, the present application also provides an automotive interior pad forming control system for realizing the automotive interior pad forming control method as described above, comprising a main heating module, an auxiliary heating module, a temperature monitoring module, a main heating control module and an auxiliary heating control module.

[0040] The main heating module comprises a hot oil device, a circulating pump and an oil tank.

[0041] The auxiliary heating module comprises a plurality of electric heating elements.

[0042] The temperature monitoring module is configured to obtain actual temperatures corresponding to a plurality of monitoring points in a mold cavity.

[0043] The main heating control module is configured to determine an optimal temperature control curve of the hot press forming process according to the interior pad model, control the main heating module to heat the mold cavity in a temperature rising sub-stage, obtain a current maximum temperature according to the actual temperatures corresponding to the plurality of monitoring points, and set the main heating module to a constant temperature mode when the current maximum temperature reaches a target constant temperature of the current temperature control stage.

[0044] The auxiliary heating control module is configured to configure working parameters of the auxiliary heating module according to the maximum temperature and the actual temperatures corresponding to the monitoring points.

[0045] The present application has the following advantages:

[0046] The present application realizes automatic stage switching through timing driving based on the optimal temperature control curve, guarantees sufficient melting and shaping of the material, and improves product size precision and surface quality; through the collaborative control of the main heating module and the auxiliary heating module, the overall temperature of the mold cavity is quickly ensured to reach the target value and remain stable, while local temperature difference is eliminated, so as to balance the rapid response and steady precision of the temperature in the hot press forming process.

[0047] The present application quickly approaches the target temperature through the first temperature rising control mode based on fuzzy logic, then precisely suppresses overshoot through the second temperature rising control mode based on model prediction, dynamically switches strategies based on the first temperature error and the first error change rate to balance real-time performance and control precision, so as to adapt to the application scenario of high-precision forming.

[0048] The present application establishes independent closed-loop control for each auxiliary heating element, calculates the optimal power sequence in the prediction time domain, reduces invalid energy consumption, and accurately compensates for the temperature hysteresis of the mold edge or complex profile area, thereby improving overall temperature uniformity. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0051] Figure 1 A flowchart of a car interior pad forming control method according to an embodiment of the present application;

[0052] Figure 2 A flowchart of determining the optimal temperature control curve of the hot forming process according to the type of the interior pad according to an embodiment of the present application;

[0053] Figure 3 A flowchart of heating the mold cavity by the main heating module according to an embodiment of the present application;

[0054] Figure 4 A flowchart of heating the mold cavity by the main heating module according to another embodiment of the present application. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of the present application.

[0056] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0057] In addition, the description related to "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0058] Embodiment 1

[0059] Please refer to Figure 1 The present application provides a kind of automobile interior pad forming control method, comprising the following steps:

[0060] Determine the optimal temperature control curve of hot forming process according to the model of interior pad;The optimal temperature control curve includes several temperature control stages;The temperature control stage includes temperature rising substage and constant temperature substage;

[0061] In temperature rising substage, the mold cavity is heated by main heating module, and the current maximum temperature is obtained according to the actual temperature of several monitoring points in the mold cavity;

[0062] If the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module is set to constant temperature mode, and the working parameters of auxiliary heating module are configured according to the actual temperature of each monitoring point and the maximum temperature.

[0063] After the duration of main heating module in constant temperature mode reaches the target constant temperature time, enter the next temperature control stage.

[0064] In the present application, the optimal temperature control curve is divided into multiple temperature control stages, each stage contains temperature rising substage and constant temperature substage. The main heating module executes the following operations according to the preset temperature control curve:

[0065] In temperature rising substage, the mold cavity is quickly heated to target temperature, and the temperature rising rate and time need to be controlled to avoid uneven temperature gradient.

[0066] In constant temperature substage, the target temperature is maintained stable to ensure that the material is fully melted or shaped until the preset target constant temperature time is reached. The specific implementation is that the main heating module maintains the temperature stable by PID control or fuzzy logic, while the auxiliary heating module compensates for local temperature difference (such as low temperature area at the junction of thick and thin)

[0067] In a temperature control stage, the trigger condition for switching from temperature rising substage to constant temperature substage is that the maximum surface temperature of the mold cavity reaches the target constant temperature of the current temperature control stage, and the main heating module switches to constant temperature mode.

[0068] When entering the constant temperature sub-stage, the system built-in timer records the constant temperature mode duration, and when the constant temperature mode duration is equal to or exceeds the preset target constant temperature time, it is determined that the current temperature control stage is completed. Before the current temperature control stage is completed, the parameters of the next temperature control stage are loaded according to the optimal temperature control curve, and when it is determined that the current temperature control stage is completed, it is switched from the constant temperature sub-stage of the current temperature control stage to the next temperature control stage or enters the cooling stage.

[0069] The application realizes automatic stage switching through timing driving based on the optimal temperature control curve, guarantees sufficient melting and shaping of the material, and improves the product size precision and surface quality; through the collaborative control of the main heating module and the auxiliary heating module, the overall temperature of the mold cavity is ensured to quickly reach the target value and remain stable, and local temperature difference is eliminated.

[0070] Specifically, the steps of the automobile interior pad forming control method of the embodiment of the application are described in detail as follows:

[0071] An automobile interior pad forming control method, comprising the steps of:

[0072] S1, determining the optimal temperature control curve of the hot press forming process according to the interior pad model; the optimal temperature control curve comprises a plurality of temperature control stages; the temperature control stage comprises a heating sub-stage and a constant temperature sub-stage;

[0073] Different interior pad models correspond to different material combinations, thicknesses, and contour complexities. Based on the interior pad model, the optimal temperature control curve is matched, and the optimal temperature control curve is divided into a plurality of temperature control stages, each temperature control stage comprising a plurality of heating sub-stages and constant temperature sub-stages, the heating sub-stage being provided with a corresponding target heating rate and target heating time: for example, from 30 seconds to 35 seconds, so that the temperature distribution is more uniform, and the constant temperature sub-stage being provided with a corresponding target constant temperature and target constant temperature time. For example, for PU foaming material, it can be heated to a certain temperature first, then kept at a certain target constant temperature for a certain target constant temperature time, and then heated to the final forming temperature.

[0074] In an embodiment, referring to Figure 2 , the optimal temperature control curve of the hot press forming process is determined according to the interior pad model, specifically comprising the steps of:

[0075] S101, determining the material thermal parameters of each layer of material corresponding to the interior pad model through experiments;

[0076] The material thermal data includes thermal conductivity, specific heat capacity, glass transition temperature and melting temperature. In this step, the material thermal parameters of each layer of the interior trim pad are tested and recorded. Specifically, the glass transition temperature and melting temperature of the material can be measured by a differential scanning calorimeter, and the thermal conductivity and specific heat of the material can be measured by a thermal conductivity tester. The target constant temperature time is extended, for example, from 30 seconds to 35 seconds, so that the temperature distribution is more uniform. The glass transition temperature and melting temperature are the core basis for subsequent temperature control curve design and temperature simulation. In an embodiment, the interior trim pad is a composite material formed by hot pressing a fabric layer (PET / PA), a middle skeleton layer (PE / PP / EVA) and a bottom layer (non-woven fabric).

[0077] S102, constructing a test temperature control curve based on the material thermal parameters of each layer of material; the test temperature control curve includes several temperature control stages and corresponding target constant temperature temperatures;

[0078] Based on prior knowledge, the target heating rate and target heating time of the heating sub-stage are set according to the glass transition temperature of the material thermal parameter, and the target constant temperature temperature and target constant temperature time of the constant temperature sub-stage are set according to the melting temperature.

[0079] S103, constructing a three-dimensional model of the interior trim pad, and setting simulation parameters of the three-dimensional model according to the material thermal parameters;

[0080] Specifically, a three-dimensional model of the interior trim pad mold is established using simulation software (such as COMSOL), and the three-dimensional model is divided into a layered structure according to the actual size and structural characteristics of the interior trim pad. Then, the material thermal conductivity and specific heat capacity measured in S101 are input into the three-dimensional model to define the thermal properties of the layered structure in the simulation software.

[0081] S104, simulating the three-dimensional model according to the test temperature control curve to obtain temperature simulation data corresponding to a plurality of time points;

[0082] Based on the simulation model file containing material properties and mold structure obtained through the above process,

[0083] Load the test temperature control curve, perform transient heat conduction simulation according to the set first time step (such as every 5 seconds), and extract temperature simulation data of a plurality of sampling positions on the mold surface with the first time step as the data collection interval. The sampling positions include grid points sampled uniformly, as well as the center, edge and thick-thin junction.

[0084] S105, obtaining temperature standard deviation corresponding to each time point according to the temperature simulation data;

[0085] For each sampling time point, based on the temperature simulation data of a plurality of sampling positions on the mold surface, the temperature standard deviation of the sampling time point is automatically calculated.

[0086] S106, if the temperature standard deviation is greater than the first uniformity threshold, adjusting the corresponding temperature control stage in the test temperature control curve according to the difference between the temperature standard deviation and the first uniformity threshold, and returning to step S104; otherwise, taking the test temperature control curve as the optimal temperature control curve.

[0087] The embodiment optimizes the temperature control curve by experimentally determining the thermal parameters of the material and constructing a three-dimensional simulation model, so as to guide the setting of process parameters, reduce trial and error costs, and ensure the temperature control adaptability and process stability of different interior trim pad models.

[0088] Based on the set first uniformity threshold (such as 3°C), mark the time points and the corresponding temperature control stages whose temperature standard deviation is higher than the first uniformity threshold. If the temperature standard deviation of a certain temperature control stage is higher than the first uniformity threshold, the corresponding temperature control stage in the test temperature control curve is adjusted.

[0089] In an embodiment, the adjustment of the corresponding temperature control stage in the test temperature control curve is specifically: if the temperature standard deviation exceeds the standard in the temperature rising sub-stage, the target temperature rising rate is reduced and the target temperature rising time is prolonged; if the temperature standard deviation exceeds the standard in the constant temperature sub-stage, the target constant temperature is increased and / or the target constant temperature time is prolonged.

[0090] In the present application, the main reason for the temperature standard deviation exceeding the standard in the temperature rising sub-stage is that the target temperature rising rate is too fast or the target temperature rising time is insufficient, resulting in too large temperature gradient in different areas of the mold, which can be specifically because the thick-walled area lags behind the thin-walled area in temperature rising due to large heat capacity, so it is necessary to reduce the temperature gradient, for example, from 5°C / s to 3°C / s, so that heat is more uniformly transmitted; or the complex profile area deviates from the expected local temperature due to uneven heat absorption efficiency, so it is necessary to provide more time for the thick-walled or complex area to absorb heat. The main reason for the temperature standard deviation exceeding the standard in the constant temperature sub-stage is that the target constant temperature or time is insufficient, resulting in insufficient melting of the material or unstable temperature distribution, which can be specifically because the target constant temperature of the sampling point is lower than the melting temperature of the material, resulting in incomplete melting in some areas, so it is necessary to increase the target constant temperature to ensure that the material melting requirement is met; or the target constant temperature time is too short, and heat is not fully conducted to the deep area of the mold, so it is necessary to prolong the target constant temperature time to make the temperature distribution more uniform.

[0091] The embodiment dynamically adjusts the temperature control parameters of the exceeding stage to set the target temperature rising rate, the target temperature rising time, the target constant temperature, and prolong the target constant temperature time, so as to specifically eliminate the problem of uneven temperature distribution, such as relieving the temperature lag caused by the heat capacity difference between thick and thin areas.

[0092] S2, in the temperature rising sub-stage, heating the mold cavity by the main heating module, and obtaining the current maximum temperature according to the actual temperatures of the monitoring points in the mold cavity;

[0093] At the beginning of the temperature increasing sub-stage, the main heating module is started to heat the whole mold cavity. During the heating process, the temperature data of each monitoring point in the mold cavity is monitored in real time, which is recorded as the temperature data corresponding to the monitoring point. Moreover, the maximum value of the temperature data of the monitoring point is calculated in real time. In the present application, the monitoring points are usually distributed at key positions of the mold cavity, which are usually uniformly sampled grid points, regions with uneven material thickness, or complex profile parts.

[0094] In an embodiment, the main heating module is an oil heating circulating device; the oil heating circulating device comprises a hot oil device, a circulating pump and an oil tank. The hot oil device is used to heat the heat conducting oil; the circulating pump is used to deliver the heat conducting oil from the hot oil device to the mold cavity, and then deliver the returned oil of the heat conducting oil back to the hot oil device for re-heating; and the oil tank is used to store the hot oil to ensure smooth circulation of the heat conducting oil.

[0095] In the implementation process, the heat conducting oil in the hot oil furnace is heated to a target constant temperature by electric heating or steam heating, and the target constant temperature is usually between 100°C and 300°C, depending on the requirements of the interior trim pad material. The circulating pump delivers the hot oil into the heating pipes or serpentine pipes in the mold cavity, and transmits heat to the interior trim pad material in the mold cavity through heat conduction to ensure that the overall temperature in the mold cavity can be uniformly increased.

[0096] In an embodiment, please refer to Figure 3 , the heating of the mold cavity by the main heating module comprises the steps of:

[0097] S211, setting a fuzzy control rule;

[0098] The fuzzy control rule defines that the input variable is the first temperature error and the first error change rate, and processes the first temperature error and the first error change rate by using a triangular membership function to divide 5 fuzzy levels, including negative large (NB), negative small (NS), zero (ZE), positive small (PS) and positive large (PB); and sets the fuzzy output corresponding to the fuzzy level of the first temperature error and the first error change rate (for example: “if the error is positive large and the first error change rate is positive large, then increase the power greatly”).

[0099] S212, calculating the first temperature error and the first error change rate according to the target constant temperature and the current maximum temperature;

[0100] The temperature of all monitoring points on the surface of the mold cavity is read in real time, the maximum value is taken as the current maximum temperature, then the first temperature error is obtained by subtracting the target constant temperature from the current maximum temperature, and the first error change rate is obtained by dividing the difference of the first temperature error of two adjacent time steps by the first time step.

[0101] S213, mapping the first temperature error and the first error change rate to a fuzzy set, and determining the output power of the main heating module according to the fuzzy set and a fuzzy control rule.

[0102] Based on the foregoing fuzzy levels, the first temperature error and the first error change rate are mapped to a fuzzy set (including "negative large", "negative small", "zero", "positive small", "positive large") in this step, and then a fuzzy output is obtained according to the fuzzy control rule and converted into a specific power adjustment value.

[0103] The embodiment realizes fast response through fuzzy control. Since the first temperature error and the first error change rate are mapped to a fuzzy set and the output power of the main heating module is determined according to the fuzzy control rule, an accurate mathematical model is not required to adapt to the nonlinearity of the system.

[0104] In another embodiment, referring to Figure 4 , the heating of the mold cavity by the main heating module includes the steps of:

[0105] S221, setting a fuzzy control rule of the first temperature control mode and an optimization objective function of the second temperature control mode;

[0106] The fuzzy control rule of the first temperature control mode is the same as S211 of the foregoing embodiment. The fuzzy control rule defines that the input variables are the first temperature error and the first error change rate, and the first temperature error and the first error change rate are processed by using a triangular membership function to divide five fuzzy levels, including negative large (NB), negative small (NS), zero (ZE), positive small (PS), and positive large (PB). The fuzzy control rule sets the fuzzy output corresponding to the fuzzy levels of the first temperature error and the first error change rate.

[0107] The optimization objective function of the second temperature control mode is constructed by using a first-order heat conduction model. The first-order heat conduction model is represented as follows:

[0108] ;

[0109] wherein, represents the maximum current temperature, represents the maximum temperature at the next time step, represents a first time step, represents the output power at the current time step, represents the ambient temperature, R represents the thermal resistance, and C represents the heat capacity. The values of the thermal resistance R and the heat capacity C are fitted by experiments.

[0110] The optimization objective function is represented as follows:

[0111] ;

[0112] wherein, represents a target constant temperature, represents a prediction time domain, represents a control time domain, represents an input weight coefficient, represents a power change amount, And the optimization objective function satisfies the constraint condition:

[0113] ,

[0114] wherein, is the maximum output power of the main heating module.

[0115] S222, calculating a first temperature error and a first error change rate according to the target constant temperature and the current maximum temperature;

[0116] Step S222 is the same as S212 of the foregoing embodiment, the temperature of all monitoring points on the mold cavity surface is read in real time, the maximum value is taken as the current maximum temperature, then the first temperature error is obtained by subtracting the target constant temperature from the current maximum temperature, and the first error change rate is obtained by dividing the difference between two adjacent time steps of the first temperature error by the first time step.

[0117] S223, determining a temperature rise control strategy according to the first temperature error and the first error change rate; the temperature rise control strategy includes a first temperature rise control mode and a second temperature rise control mode;

[0118] The first temperature rise control mode is: mapping the first temperature error and the first error change rate into a fuzzy set, and determining the output power of the main heating module according to the fuzzy set and a fuzzy control rule;

[0119] The second temperature rise control mode is: substituting the current maximum temperature into an optimization objective function to obtain the output power of the main heating module.

[0120] Further, the determining of the temperature rise control strategy according to the first temperature error and the first error change rate is specifically: when the first temperature error is greater than a first temperature error threshold or the first error change rate is greater than a first error change rate threshold, the first temperature rise control mode is selected as the temperature rise control strategy; when the first temperature error is less than or equal to the first temperature error threshold and the first error change rate is less than or equal to the first error change rate threshold, the second temperature rise control mode is selected as the temperature rise control strategy.

[0121] For example, the first temperature rise mode is adopted when the first temperature error is > 5°C or the first error change rate is > 2°C / s, which is used for quickly eliminating large deviation; the second temperature rise mode is adopted when the first temperature error is ≤ 5°C and the first error change rate is ≤ 2°C / s, which is used for fine-tuning.

[0122] The embodiment quickly approaches the target temperature through the fuzzy logic of the first temperature control mode, and then accurately suppresses overshoot through the model prediction of the second temperature control mode. The dynamic switching strategy based on the first temperature error and the first error change rate takes into account the real-time performance and the control accuracy, so as to adapt to the application scenarios of high-precision molding.

[0123] S3, if the current temperature maximum reaches the target constant temperature of the current temperature control stage, the main heating module is set to a constant temperature mode, and the working parameters of the auxiliary heating module are configured according to the actual temperature of each monitoring point corresponding to the temperature maximum.

[0124] After the temperature maximum reaches the target constant temperature, the main heating module switches to the constant temperature mode to maintain the current temperature stable. Specifically, after the main heating module switches to the constant temperature mode, the main heating module controls the current temperature maximum within the deviation allowed range of the target constant temperature, such as ±0.5°C. Then, the difference between the temperature maximum and the actual temperature of each monitoring point is calculated to determine the temperature deviation of each point. According to the deviations, the working parameters of the auxiliary heating module are configured to locally compensate for the temperature difference.

[0125] It should be noted that the optimal temperature control curve is generated based on the material thermal parameters and the three-dimensional simulation model, and its essence is a solution that meets the temperature standard deviation less than or equal to the first uniformity threshold, which is used to provide a theoretical basis for the control of the main heating module. However, the heat conduction characteristics of the multi-layer materials of the interior trim pad (such as the base material and the foaming layer) may have batch differences, and the heat absorption rates of complex geometric profiles or thick-thin junction areas are different, and the simulation cannot completely cover all local dynamic characteristics. The embodiment acquires temperature data in real time through monitoring points, identifies local low-temperature areas (such as edges or thick-thin junctions), and then independently adjusts the power of the auxiliary heating module according to the second temperature error and the change rate to compensate for the heat deficiency area.

[0126] In an embodiment, the auxiliary heating module includes a plurality of electric heating elements, which are installed near the monitoring points during implementation to quickly respond to and adjust the local temperature, ensuring that the temperature in the entire mold cavity is uniform and consistent, and avoiding local overheating or overcooling.

[0127] Further, the working parameters of the auxiliary heating module are configured according to the actual temperature of each monitoring point corresponding to the temperature maximum, including the steps of:

[0128] S31, the second temperature error of each monitoring point and the temperature maximum is calculated in real time;

[0129] S32, if the second temperature error is greater than the auxiliary heating demand threshold, the second error change rate is calculated according to the difference between the second temperature errors of two adjacent time steps;

[0130] The second error change rate is expressed as:

[0131] ;

[0132] wherein, represents the second error change rate of the i-th monitoring point, represents the second temperature error of the i-th monitoring point at the k-th time step, represents the second time step.

[0133] S33, configuring the output power of the auxiliary heating module according to the second temperature error.

[0134] The output power of the auxiliary heating module is represented as:

[0135] ;

[0136] wherein, represents the output power of the i-th electric heating element of the auxiliary heating module; represents the second temperature error of the i-th monitoring point; is an error gain coefficient, which is set according to the material heat capacity and heating efficiency; is a differential gain; i is the number of monitoring points and electric heating elements.

[0137] In the formula, the first term According to the difference between the current monitoring point and the maximum temperature, the heating demand intensity is directly reflected, and the second term According to the second error change rate, the heating demand intensity is further optimized to suppress temperature fluctuations in advance.

[0138] The embodiment establishes an independent closed-loop control for each auxiliary heating element, calculates the optimal power sequence in the prediction time domain, reduces invalid energy consumption, and accurately compensates for the temperature lag of the mold edge or complex contour area, thereby improving the overall temperature uniformity.

[0139] S4, monitoring the main heating module to enter the next temperature control stage after the duration of the constant temperature mode reaches the target constant temperature time.

[0140] In the present application, the temperature control curve is divided into multiple temperature control stages, each stage containing a temperature rising sub-stage and a constant temperature sub-stage. The main heating module performs the following operations according to the preset temperature control curve:

[0141] In the temperature rising sub-stage, the mold cavity is quickly heated to the target temperature, and the temperature rising rate and time need to be controlled to avoid uneven temperature gradient.

[0142] In the constant temperature sub-stage, the target temperature is maintained stable to ensure that the material is fully melted or shaped until the preset target constant temperature time is reached. The specific implementation is that the main heating module maintains the temperature stable through PID control or fuzzy logic, while the auxiliary heating module compensates for the local temperature difference (such as the low temperature area at the thick-thin junction)

[0143] In a temperature control stage, the trigger condition for switching from the temperature rising sub-stage to the constant temperature sub-stage is that when the maximum temperature of the mold cavity surface reaches the target constant temperature of the current temperature control stage, the main heating module is switched to the constant temperature mode.

[0144] When entering the constant temperature sub-stage, the system built-in timer records the constant temperature mode duration, and when the constant temperature mode duration is equal to or exceeds the preset target constant temperature time, it is determined that the current temperature control stage is completed. Before the current temperature control stage is completed, the parameters of the next temperature control stage are loaded according to the optimal temperature control curve, including the target temperature rising rate, the target temperature rising time, the target constant temperature, and the target constant temperature time of the next temperature control stage, and when the current temperature control stage is determined to be completed, it is switched from the constant temperature sub-stage of the current temperature control stage to the next temperature control stage or enters the cooling stage, and if it enters the next temperature control stage, it returns to step S2. In an embodiment, the target processing temperature curve includes a first temperature control stage, a second temperature control stage, a third temperature control stage, and a cooling stage. The automobile interior pad forming control method of the present application implements the first temperature control stage, the second temperature control stage, and the third temperature control stage by cyclically executing steps S2-S4 three times, and then executes the cooling stage. Since the cooling stage can be implemented by existing methods, this scheme will not be described in detail.

[0145] Embodiment 2

[0146] The present application also provides an automobile interior pad forming control system, which comprises a main heating module, an auxiliary heating module, a temperature monitoring module, a main heating control module, and an auxiliary heating control module.

[0147] The main heating module comprises a hot oil device, a circulating pump, and an oil tank.

[0148] The auxiliary heating module comprises a plurality of electric heating elements.

[0149] The temperature monitoring module is used to obtain the actual temperatures corresponding to a plurality of monitoring points in the mold cavity.

[0150] The main heating control module is used to determine the optimal temperature control curve of the hot press forming process according to the interior pad model, control the main heating module to heat the mold cavity in the temperature rising sub-stage, and obtain the current maximum temperature according to the actual temperatures corresponding to the plurality of monitoring points. When the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module is set to the constant temperature mode.

[0151] The auxiliary heating control module is used to configure the working parameters of the auxiliary heating module according to the maximum temperature and the actual temperatures corresponding to the monitoring points.

[0152] In the embodiments of the present application, it should be understood that the disclosed system and method can be implemented in other manners. For example, the described system embodiments are merely schematic. For example, the division of the modules is merely a logical function division. For another example, a plurality of modules or component subsets can be combined or integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be implemented by using some interfaces, and a mere combination of the modules or a result of the combination can be implemented in a physical manner, or can be implemented in other manners as long as there is no contradiction. The essential characteristics of the technical solutions of the embodiments should be maintained during the implementation.

[0153] The modules illustrated as separated components can or can not be physically separated, and the components illustrated as modules can or can not be physical modules, that is, can be located in one place, or can be distributed on a plurality of grid modules. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments.

[0154] In addition, each function module in each embodiment of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software function module.

[0155] The integrated module, if realized in the form of a software function module and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a grid device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a dynamic hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0156] The above description is merely specific embodiments of the present application, enabling a person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the molding of automotive interior trim pads, characterized in that: Including the following steps: The optimal temperature control curve for the hot pressing process is determined based on the model of the interior mat. The optimal temperature control curve includes several temperature control stages. Each temperature control stage includes a heating sub-stage and a isothermal sub-stage. Each isothermal sub-stage has a corresponding target isothermal temperature and target isothermal time. During the heating sub-stage, the mold cavity is heated by the main heating module, and the current maximum temperature is obtained based on the actual temperature corresponding to several monitoring points in the mold cavity. If the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module will be set to constant temperature mode, and the working parameters of the auxiliary heating module will be configured according to the maximum temperature and the actual temperature corresponding to each monitoring point. After the main heating module reaches the target constant temperature time in constant temperature mode, it enters the next temperature control stage. The step of determining the optimal temperature control curve for the hot pressing process based on the model of the interior mat specifically includes the following steps: S101. The thermal parameters of each layer of material corresponding to the model of the interior mat are determined by experiment. S102. Construct a test temperature control curve based on the material thermal parameters of each layer of material; the test temperature control curve includes several temperature control stages and corresponding target isothermal temperatures; S103. Construct a three-dimensional model of the interior mat and set the simulation parameters of the three-dimensional model according to the thermal parameters of the material. S104. Simulate the three-dimensional model according to the test temperature control curve to obtain temperature simulation data at several time points. S105. Obtain the temperature standard deviation at each time point based on the temperature simulation data. S106. If the temperature standard deviation is greater than the first uniformity threshold, adjust the corresponding temperature control stage in the test temperature control curve according to the difference between the temperature standard deviation and the first uniformity threshold, and return to step S104; otherwise, take the test temperature control curve as the optimal temperature control curve. Specifically, the adjustment of the temperature control stage in the test temperature control curve is as follows: if the temperature standard deviation exceeds the standard in the heating sub-stage, the target heating rate is reduced and the target heating time is extended; if the temperature standard deviation exceeds the standard in the isothermal sub-stage, the target isothermal temperature is increased and / or the target isothermal time is extended. The step of heating the mold cavity through the main heating module includes the following steps: Set fuzzy control rules; Calculate the first temperature error and the first error change rate based on the target constant temperature and the current maximum temperature. The first temperature error and the first error change rate are mapped to fuzzy sets, and the output power of the main heating module is determined according to the fuzzy sets and fuzzy control rules. The step of configuring the operating parameters of the auxiliary heating module based on the maximum temperature and the actual temperature corresponding to each monitoring point includes the following steps: Calculate the second temperature error between each monitoring point and the maximum temperature value in real time; If the second temperature error is greater than the auxiliary heating requirement threshold, the second error change rate is calculated based on the difference between the second temperature errors of two adjacent time steps. Configure the output power of the auxiliary heating module according to the second temperature error.

2. The method for controlling the molding of automotive interior mats according to claim 1, characterized in that: The heating of the mold cavity via the main heating module includes the following steps: Define the fuzzy control rules for the first heating control mode and the optimization objective function for the second heating control mode; Calculate the first temperature error and the first error change rate based on the target constant temperature and the current maximum temperature. A heating control strategy is determined based on a first temperature error and a first error change rate; the heating control strategy includes a first heating control mode and a second heating control mode. The first heating control mode is as follows: mapping the first temperature error and the first error change rate to a fuzzy set, and determining the output power of the main heating module according to the fuzzy set and fuzzy control rules; The second heating control mode is as follows: substitute the current maximum temperature into the optimization objective function, and solve to obtain the output power of the main heating module.

3. The method for controlling the molding of automotive interior mats according to claim 2, characterized in that: The method of determining the heating control strategy based on the first temperature error and the first error change rate is as follows: when the first temperature error is greater than the first temperature error threshold or the first error change rate is greater than the first error change rate threshold, the first heating control mode is selected as the heating control strategy; when the first temperature error is less than or equal to the first temperature error threshold and the first error change rate is less than or equal to the first error change rate threshold, the second heating control mode is selected as the heating control strategy.

4. A molding control system for automotive interior mats, characterized in that: The method for controlling the molding of automotive interior mats as described in any one of claims 1-3 includes a main heating module, an auxiliary heating module, a temperature monitoring module, a main heating control module, and an auxiliary heating control module. The main heating module includes a hot oil device, a circulating pump, and an oil tank; The auxiliary heating module includes several electric heating elements; The temperature monitoring module is used to obtain the actual temperature corresponding to several monitoring points inside the mold cavity; The main heating control module is used to determine the optimal temperature control curve for the hot pressing process based on the model of the interior mat; control the main heating module to heat the mold cavity during the heating sub-stage, and obtain the current maximum temperature based on the actual temperature corresponding to the several monitoring points; when the current maximum temperature reaches the target constant temperature of the current temperature control stage, the main heating module is set to constant temperature mode. The auxiliary heating control module is used to configure the operating parameters of the auxiliary heating module according to the maximum temperature and the actual temperature corresponding to each monitoring point.

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