Automobile part mold area temperature control method

Abstract

The invention belongs to the technical field of mold area temperature control, and particularly relates to an automobile part mold area temperature control method, which is characterized in that a temperature control area of a mold cavity channel is finely divided based on the wall thickness and heat distribution of the mold cavity channel, so that the fine division of the temperature control area is realized; and each temperature control area is accurately adjusted by combining the planned cooling time, so that the occurrence of events of non-uniform cooling of a finished product and poorer forming quality caused by not considering the wall thickness can be avoided or reduced, the cooling uniformity is optimized, the injection molding quality is improved, and meanwhile, according to the temperature value of each temperature area and the distance between the areas, the injection molding quality is improved. According to the control method, the mode of combining independent control, grouping control and overall control is adopted for the area needing to be controlled, the defects existing in the current single temperature control mode are overcome, and therefore the preheating requirement can be rapidly met, the control time is saved, the control efficiency is improved, and energy waste is avoided.

Description

Technical Field

[0001] This invention belongs to the field of mold area temperature control technology, and more specifically, relates to a method for controlling the temperature of automotive parts mold areas. Background Technology

[0002] Automotive parts are generally produced through injection molding, and temperature control during the injection molding process directly determines the yield rate. Therefore, temperature control is particularly important in the production and processing of automotive parts.

[0003] Existing technologies, such as the Chinese invention patent application with application number 202510939620.X, disclose a cooling regulation method and system for injection molds. This method acquires real-time temperature data through temperature sensors at preset measuring points in the mold cavity, generates a heat distribution model, divides the corresponding cooling circuit into sub-cooling areas, and then generates flow regulation commands based on the temperature status of each area to control the electronically controlled valves and variable frequency water pumps to regulate the flow of cooling fluid, thereby achieving precise zonal regulation of the injection mold cooling process.

[0004] Based on the existing technology, it can be seen that the current temperature control zone is mainly based on temperature distribution, and there is insufficient attention to the details of how to adjust it. There are still several problems: 1. The influence of the difference in mold wall thickness on the final effect of temperature control is not considered during the temperature control process, which leads to inconsistent cooling or preheating of finished products, causing quality problems such as shrinkage marks, deformation or dimensional accuracy that do not meet the standard requirements.

[0005] 2. Currently, only the temperature range that needs to be controlled is identified and corresponding control is performed without considering the characteristics of the mold structure, such as differences in wall thickness or regularity of shape. This single control method is time-consuming. When there are multiple areas that need to be controlled, the current control method is difficult to meet production needs and is also difficult to guarantee the accuracy and effectiveness of control.

[0006] 3. Currently, when adjusting the temperature, the principle of individual adjustment is followed. The similarity of the adjustment values ​​and the distance between the adjustment positions are not considered when adjusting multiple points, which leads to energy waste, difficulty in completing the production plan in time, and difficulty in ensuring the consistency of temperature in each area, thus affecting the overall performance of the injection molded parts. Summary of the Invention

[0007] In view of this, in order to solve the above problems, a method for temperature control in the mold area of ​​automotive parts is proposed.

[0008] The objective of this invention can be achieved through the following technical solution: This invention provides a method for temperature control in the mold area of ​​automotive parts, the method comprising: generating a thermal image by detecting the overall cavity of the mold with a thermal imager, and obtaining temperature information by identifying the thermal image.

[0009] Based on temperature information, cavity locations that do not meet the injection molding preheating requirements are selected, and the temperature control unit in that location is activated to adjust the temperature accordingly until the injection molding preheating requirements are met before injection molding is performed.

[0010] The temperature value of the cavity after the molten injection material is injected is collected in real time by the temperature sensor built into the mold. The temperature control cavity position is determined based on the current temperature value and distribution position collected by the temperature sensor and the three-dimensional spatial coordinates of the overall cavity, and the temperature of the corresponding cavity is controlled.

[0011] After the injection molding process is completed and the pressure holding process is finished, the overall cavity is divided into several temperature control zones according to the structural characteristics of the overall cavity, and the current temperature is collected according to the temperature sensor built into each temperature control zone.

[0012] Based on the current temperature of each temperature control zone, the characteristics of the injection molding material, the characteristics of the mold material, and the planned cooling time, a preset temperature control model is matched to obtain a matching temperature adjustment strategy, and cooling control is performed according to the temperature adjustment strategy.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention refines the temperature control area of ​​the mold cavity by dividing it into smaller areas based on the wall thickness and heat distribution of the mold cavity, thereby achieving a fine division of the temperature control area. By combining the planned cooling time to accurately adjust each temperature control area, the occurrence of uneven cooling and poor molding quality of the finished product due to the lack of consideration of wall thickness can be avoided or reduced, thereby optimizing the cooling uniformity and improving the injection molding quality.

[0014] (2) The present invention makes up for the shortcomings of the current single temperature control method by adopting a combination of individual control, group control and overall control of the area to be controlled according to the temperature value of each temperature zone and the distance between the zones. This allows the preheating requirements to be met quickly and saves control time, thereby improving control efficiency and avoiding energy waste.

[0015] (3) By combining the structural characteristics of the mold cavity and the characteristics of the injection molding material, the present invention adjusts the temperature control area from three dimensions: temperature difference, wall thickness difference and regularity. When any dimension exceeds the preset threshold, the area segmentation is automatically started, avoiding the lack of specificity in the current temperature control area division. This makes the temperature control area segmentation closely related to product quality, thus having clear specificity and ensuring the injection molding quality. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall implementation process of the present invention.

[0018] Figure 2 This is a schematic diagram of the temperature control process during injection molding preheating according to the present invention.

[0019] Figure 3 This is a schematic diagram of the basic area adjustment process of the present invention.

[0020] Figure 4 This is a schematic diagram of the segmentation process according to the preset segmentation rules of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 As shown, the present invention provides a method for temperature control in the mold area of ​​automotive parts. The method includes: S1, generating a thermal image by detecting the overall cavity of the mold with a thermal imager, and obtaining temperature information by identifying the thermal image.

[0023] The process of obtaining the temperature information includes: importing a three-dimensional model of the entire cavity, correcting the distortion of the thermal image, and then establishing a mapping relationship between the pixels of the thermal image and the three-dimensional spatial coordinates of the entire cavity using the SIFT algorithm.

[0024] The thermal image is identified to obtain the temperature regions and their corresponding temperature values, and the cavity locations to which each temperature region belongs are marked.

[0025] The temperature information is composed of the temperature value corresponding to each temperature region and the location of the cavity to which it belongs.

[0026] Distortion correction is an existing image processing technique and will not be described in detail in this invention. The SIFT algorithm is an existing mapping algorithm and will not be described in detail in this invention.

[0027] S2. Based on temperature information, filter cavity locations that do not meet the injection molding preheating requirements, and activate the temperature control unit in that location to adjust the temperature accordingly until the injection molding preheating requirements are met before performing injection molding.

[0028] Among them, the injection preheating requirement is the injection preheating threshold, which can be obtained by referring to the injection temperature reference table for different materials provided by the supplier and the analysis report of past actual production cases.

[0029] The process of screening cavity locations that do not meet the injection molding preheating requirements includes: matching the preset preheating target temperature value of the corresponding temperature zone based on the cavity location belonging to each temperature zone.

[0030] The temperature values ​​corresponding to each temperature zone are compared with their preset preheating target temperature values.

[0031] If the temperature value corresponding to a certain temperature zone is lower than its preset preheating standard temperature value and the difference between the temperature value and the preset preheating standard temperature value exceeds the preset allowable range, the temperature zone is marked as a cavity location that does not meet the injection molding preheating requirements.

[0032] It should be noted that the preset preheating temperature value mentioned above can be obtained through extensive experimental calculations or by consulting injection molding process parameter reference tables. When determined by experimental calculations, the recommended mold temperature for the material can be used as the center to set 3 to 5 sets of gradient temperatures. Then, injection molding is performed at different preheating temperatures to detect product defects and find the critical temperature between no defects and defects. At the same time, under extreme conditions such as ambient temperature fluctuations and continuous production, the critical temperature between no defects and defects is tested again to find the critical temperature between no defects and defects. The lowest defect-free temperature is taken as the preset preheating temperature value for this region, thereby ensuring the applicability of the preset preheating temperature value.

[0033] Understandably, the preset preheating temperature mentioned above is the minimum preheating temperature that the mold cavity needs to reach before injection molding, to ensure that the molten material can flow and fill normally after injection and reduce defects.

[0034] It should be noted that the preset allowable range of the preheating temperature value mentioned above needs to take into account the characteristics of the mold material, the characteristics of the injection molding material, the requirements of the injection molding process, and the needs of production stability. The preset preheating temperature value can be used as a benchmark, and the setting can be made comprehensively according to the wall thickness, heat sensitivity, and impact on the quality of injection molded parts in different temperature areas. A floating range of ±3℃ to ±8℃ can be defined by default. For example, a smaller range of ±3℃ to ±5℃ can be used for thin-walled areas with high molding accuracy requirements, and a larger range of ±5℃ to ±8℃ can be used for thick-walled or non-critical areas.

[0035] Among them, the characteristics of mold materials include mechanical, thermal and processing properties. Mechanical properties such as hardness, wear resistance, compressive strength and toughness are used to withstand the high pressure and friction during injection molding. Thermal properties such as thermal conductivity and coefficient of thermal expansion affect heat transfer efficiency and mold dimensional stability. Processing properties such as machinability and polishability determine the precision and surface quality of the mold cavity.

[0036] Among them, the characteristics of injection molding materials include thermal, mechanical, flowability and chemical stability properties. Thermal properties include thermal conductivity, specific heat capacity, melting temperature and crystallization temperature. Mechanical properties include tensile strength, impact toughness, hardness and elastic modulus. Flowability includes melt flow rate and viscosity as a function of temperature or shear rate. Chemical stability includes corrosion resistance and aging resistance.

[0037] Please see Figure 2 As shown, the steps for corresponding temperature control include: marking the cavity locations that do not meet the injection molding preheating requirements as control locations, and counting the number of control locations.

[0038] When there is only one location, the difference between the temperature value corresponding to the control position and the preset preheating target temperature value is used as the control temperature value, and the temperature control unit in the control position is started to execute the heating command based on the control temperature value.

[0039] When there is more than one location, the distance between each control location is calculated.

[0040] If the maximum distance does not exceed the preset interval distance and the standard deviation of the controlled temperature value at each controlled position is less than the preset threshold, connect each controlled position to generate an overall controlled area.

[0041] The average control temperature value at each control position is taken as the control temperature value of the overall control area, and the temperature control unit in the overall control area is activated to heat the system based on the control temperature value.

[0042] If the distance between adjacent control positions exceeds the preset interval distance, or if the distance between adjacent control positions does not exceed the preset interval distance and the difference in the control temperature values ​​of the adjacent control positions exceeds the preset adjacent control temperature difference, the temperature control units in the adjacent control positions are activated for heating based on the control temperature values.

[0043] Traverse all adjacent control positions, bind and mark adjacent control positions that are less than the preset interval, and form an overall control group by combining all adjacent control positions that are continuously bound and marked.

[0044] The average control temperature value of each cavity position within the overall control group is taken as the control temperature value of the overall control group, and the temperature control unit of the overall control group is activated to execute the heating command based on the control temperature value.

[0045] It should be noted that the temperature control unit mentioned above is obtained by integrating a heating unit and a cooling unit. The heating unit can be an electric heating tube for heating small cavity areas or complex structural areas that heat up rapidly, or a medium heating tube for heating areas with high temperature uniformity requirements. The cooling unit can be a straight-through cooling medium channel, or it can be suitable for a spray cooling device. The medium can be water by default, and the spray cooling device usually adopts an industrial mold spray cooling system by default. The spray cooling system integrates multiple sets of adjustable nozzles and is used in conjunction with a temperature sensor array.

[0046] It should be noted that the preset threshold values ​​of the temperature control values ​​of each control position mentioned above need to be determined comprehensively based on the consistency of temperature control within the overall control area, the similarity of temperature requirements of each control position, the quality requirements of the injection molded parts, and the material of the injection molded parts. For example, when the finished product is a key component of the power system made of glass fiber reinforced PA, the default value is usually 2℃; when the finished product is an electronic component housing made of PC, the default value is usually 3℃; and when the finished product is an interior trim part made of ABS, the default value is usually 4℃.

[0047] Understandably, the preset thresholds for each control position mentioned above are critical values ​​for judging whether the standard deviation of the control temperature values ​​of multiple control positions is acceptable, and are used to decide whether to merge them into an overall control area.

[0048] It should be noted that the preset interval distance of each control position mentioned above is based on the effective range of the temperature control unit and the synergy of temperature control in adjacent areas. Combined with the mold structure and the thermal conductivity of the material, the maximum spatial distance that can ensure temperature uniformity when adjacent positions are combined for control is taken as the preset interval distance. It is usually set to 5mm to 15mm, and the specific value can be selected according to the specific structure and precision of the mold. The more complex the injection mold structure and the higher the precision, the smaller the value should be.

[0049] It should be noted that the preset proximity control temperature difference mentioned above represents the temperature difference value required for overall control between two adjacent control positions that meet the preset interval distance.

[0050] It should be noted that the setting of the preset adjacent temperature difference mentioned above needs to be combined with the thermal conduction characteristics of adjacent control positions, the correlation of mold structure and the quality requirements of injection molded parts. It also needs to be comprehensively determined based on the distance between the two, the thermal diffusivity of the material and the degree of influence on molding accuracy. It is usually set to 5℃~10℃, and the specific value can be selected according to the degree of influence. The degree of influence is inversely proportional to the preset adjacent temperature difference, usually presented in the form of percentage. For example, when the degree of influence is 100%, the value is 5℃, when the degree of influence is 0%, the value is 10℃, and when the degree of influence is 60%, the value is 8℃.

[0051] This invention, by combining individual control, group control, and overall control of the area to be controlled based on the temperature values ​​of each temperature zone and the distance between zones, overcomes the shortcomings of the current single temperature control method, thereby quickly achieving the preheating requirements, saving control time, improving control efficiency, and avoiding energy waste.

[0052] S3. The temperature value of the cavity after the molten injection material is injected is collected in real time by the temperature sensor built into the mold. The temperature control cavity position is determined according to the current temperature value and distribution position collected by the temperature sensor and the three-dimensional spatial coordinates of the overall cavity, and the temperature of the corresponding cavity is controlled.

[0053] The method for determining the location of the temperature control cavity in step S3 includes: comparing the distribution location of each temperature sensor with the three-dimensional spatial coordinates of the overall cavity to obtain the mapped cavity location of each temperature sensor.

[0054] The preset injection threshold corresponding to the mapped cavity position is matched based on the mapped cavity position of each temperature sensor.

[0055] The current temperature value collected by each temperature sensor is compared with the preset injection threshold of its mapped cavity position.

[0056] If the current temperature value collected by a temperature sensor is lower than the preset injection threshold of its mapped cavity position and the difference between the temperature sensor and the preset injection threshold exceeds the preset allowable range, the mapped cavity position of the temperature sensor is marked as the temperature control cavity position.

[0057] Furthermore, the specific steps for temperature control of the corresponding cavity in step S3 are as follows: the difference between the current temperature value of the temperature control cavity position and the preset injection molding threshold is used as the initial cavity control temperature value.

[0058] Based on the preliminary cavity control temperature value, the wall thickness of the temperature control cavity, and the characteristics of the cavity material, the target cavity control temperature value is calculated.

[0059] The temperature control unit that controls the position of the cavity is activated to regulate the cavity temperature according to the target temperature value corresponding to that position.

[0060] The calculation process for the target cavity temperature control value includes: calculating the comprehensive compensation coefficient based on the cavity wall thickness and material thermal properties.

[0061] The target cavity control temperature value is obtained by correcting the initial cavity control temperature value according to the comprehensive compensation coefficient, wherein the correction refers to multiplying the comprehensive compensation coefficient by the initial cavity control temperature value.

[0062] Specifically, the expression for the comprehensive compensation coefficient is as follows: ,in Due to the thick walls of the cavity, Reflects cavity wall thickness With thermal conductivity The effect of interaction on temperature compensation It can be obtained through regression fitting of temperature measurement experiments on a large number of molds with similar cavity structures made of the same material. Characterizing thermal response speed The weighting of the compensation can be calibrated based on the dynamic temperature measurement curves of different temperature control units. The correction value to compensate for the temperature difference in the mold base can be determined through a steady-state temperature measurement experiment of the empty mold. Thermal response speed refers to the time it takes for a temperature control unit to adjust from its current temperature state to the target temperature and reach a stable state after receiving a heating or cooling command, or the rate at which the temperature changes with the control command. It can be obtained through a large number of experiments.

[0063] It should be added that the specific process obtained from the large number of experiments was to start the temperature sensor in the actual injection mold or simulated temperature control environment to collect data in real time, record the time from the initial temperature to the target temperature or calculate the amount of temperature change per unit time.

[0064] The time required to rise to or fall to the target temperature is usually determined by the time it takes to reach the target temperature. The time within the stable range of 0.5℃ to 1℃ shall be used as the standard.

[0065] Use the above , and This is to ensure stable production by adapting to the complex coupling characteristics of injection molding temperature control, simplifying model engineering applications, and balancing theoretical accuracy with production robustness.

[0066] Understandably, the preset injection molding threshold corresponding to the mapped cavity location mentioned above is determined comprehensively based on the structural characteristics of the mapped cavity location, such as wall thickness, curvature, melting characteristics of the injection molding material, and molding quality requirements, combined with the functional importance of the location in the injection molded part. The default value range is usually 220℃~260℃, and the specific value can be selected based on the structural characteristics of the finished product and the thermal properties of its material. For example, when the finished product is a thick-walled, high-curvature transmission part made of PA+glass fiber, the value is 255℃; when the finished product is a precision-hole electronic housing made of PC, the value is 245℃; and when the finished product is a thin-walled, low-curvature interior part made of ABS, the value is 225℃.

[0067] The standard for defining functional importance is as follows: positions that directly affect the realization of the core functions of the injection molded part, such as transmission, sealing, and load-bearing, are of high importance, while positions that only undertake non-core functions such as decoration and auxiliary positioning are of low importance.

[0068] It should be noted that the preset injection threshold mentioned above represents the temperature at which the injection material can continue to flow smoothly through the mapped cavity during injection.

[0069] The importance of the cavity location is determined as follows: if the cavity location is a key functional area of ​​the injection molded part, such as a fluid channel cavity or a stress-bearing structure cavity, its molding quality directly affects the core indicators of the injection molded part, such as sealing performance and mechanical load-bearing capacity, and is therefore determined to be of high importance; if it is only used for process assistance, such as an exhaust cavity or a non-critical positioning cavity, and is not directly related to the core function, it is determined to be of low importance.

[0070] It should be noted that the aforementioned preset allowable range represents the maximum allowable deviation between the current temperature value of the mapped cavity location and the preset injection threshold. It can be set specifically based on the importance of the cavity location, material characteristics, and temperature control accuracy requirements.

[0071] S4. After the injection molding process is completed and the pressure holding process is finished, the overall cavity is divided into several temperature control zones according to the structural characteristics of the overall cavity, and the current temperature is collected according to the temperature sensor built into each temperature control zone.

[0072] Specifically, the method for dividing the temperature control area includes: A1. Marking each key node in the three-dimensional model of the overall cavity, using the key nodes as dividing endpoints and the connecting lines of the areas where the key nodes are located as dividing lines, dividing the overall cavity into several basic areas.

[0073] A2. Based on the structural parameters of the cavity and the thermal conductivity and specific heat capacity of the injection molding material, simulate the current heat distribution of each basic region, and obtain the maximum temperature difference and average temperature value of the basic region according to the heat distribution.

[0074] A3. Extract the three-dimensional contours of each basic region, identify the wall thickness of each cavity location point in the corresponding basic region based on the three-dimensional contours, calculate the average cavity wall thickness of each basic region, and extract the maximum wall thickness.

[0075] A4. Based on the maximum temperature difference, average temperature value, three-dimensional profile, average cavity wall thickness and maximum wall thickness of each basic region, as well as the wall thickness of each cavity location point within each basic region, the basic regions are adjusted to output the final temperature control regions.

[0076] This invention refines the temperature control area of ​​the mold cavity by dividing it based on the wall thickness and heat distribution of the mold cavity. This achieves a precise division of the temperature control area. By combining the planned cooling time to accurately adjust each temperature control area, it can avoid or reduce the occurrence of uneven cooling and poor molding quality of the finished product due to the failure to consider the wall thickness. This optimizes cooling uniformity and improves injection molding quality.

[0077] Please see Figure 3 As shown, the process of adjusting the basic region in step A4 includes: A41, identifying the three-dimensional contour of each basic region and statistically obtaining the regularity of each basic region.

[0078] It should be noted that the above-mentioned regularity calculation method includes: obtaining the projection surface contour shape of each basic region based on the three-dimensional contour; if the projection surface contour shape of a certain basic region is similar to a circle, the basic region is divided into several sets of sub-contours by fan-shaped division.

[0079] The term "similar" refers to the fact that the overlap rate between the projection surface contour and the contour of a circle or rectangle is greater than a preset overlap rate threshold, which is set based on a similarity experience threshold.

[0080] If the projection surface of a certain basic region is similar to a rectangle, the basic region is divided into multiple sets of sub-contours by planar grid.

[0081] Each sub-contour within a certain base area is grouped into two groups to obtain contour groups. The sub-contours of each contour group are compared to obtain the overlap rate of each contour group. The overlap rate is the ratio of the overlapping volume to the larger volume in the contour group.

[0082] The overlapping volume of each contour group is compared with the preset overlapping volume threshold, and the number of contour groups that are greater than the preset overlapping volume threshold is counted and recorded as the number of regular contour groups.

[0083] It should be added that the overlap volume threshold can be determined by referring to historical valid data of similar injection molded parts contour matching, combined with mold structure accuracy requirements and molding quality standards, and verified by experimental testing. Among them, historical valid data refers to the relevant records of overlap volume in the same or similar injection molded parts contour matching scenarios that have been verified in practice to ensure mold molding accuracy, avoid contour overlap defects, and meet production quality standards.

[0084] If the ratio of the number of regular contour groups to the total number of regular contour groups is 1, the final regularity is assigned a value of 1; otherwise, the minimum overlapping volume is selected, and the ratio of the minimum overlapping volume to the preset overlapping volume threshold is used as the regularity correction coefficient. The product of the regularity correction coefficient and the ratio of the number of regular contour groups to the total number of regular contour groups is used as the final regularity.

[0085] A42. Determine whether any of the following conditions are triggered in each basic area. If triggered, start the basic area adjustment command: the maximum temperature difference is greater than the preset temperature difference.

[0086] The difference between the maximum wall thickness and the average cavity wall thickness exceeds the preset wall thickness difference.

[0087] The regularity is lower than the preset high regularity threshold.

[0088] like Figure 3 As shown, trigger condition 1 corresponds to a maximum temperature difference greater than a preset temperature difference, trigger condition 2 corresponds to a difference between the maximum wall thickness and the average cavity wall thickness exceeding a preset wall thickness difference, and trigger condition 3 corresponds to a regularity lower than a preset high regularity threshold.

[0089] Understandably, the aforementioned preset temperature difference setting can be determined by taking the influence of temperature distribution uniformity within the basic area on injection molding quality as the core, and combining the material's thermal sensitivity and molding process requirements to comprehensively determine the maximum allowable temperature difference that can ensure temperature control accuracy and injection molded part quality stability in the same area. Furthermore, the specific value of the preset temperature difference can be determined according to the thermal characteristics of the finished product type and material. For example, when the finished product is a precision electronic component made of PC or ABS, the preset temperature difference is 1.5℃; when the finished product is an automotive structural component made of PP + glass fiber, the preset temperature difference is 2℃; and when the finished product is a large interior part made of ABS, the preset temperature difference is 3.5℃.

[0090] It should be noted that the above-mentioned preset temperature difference is the critical temperature difference value for determining whether the basic area needs to be divided. When the maximum temperature difference in the basic area exceeds this value, the area adjustment needs to be initiated.

[0091] It should be noted that the aforementioned preset wall thickness difference focuses on the impact of the uniformity of wall thickness within the basic area on temperature control and injection molding quality. Combining material characteristics and molding requirements, the maximum allowable wall thickness deviation that ensures temperature control consistency and injection molding stability in the same area is taken as the corresponding preset wall thickness difference, which is usually set to 0.1mm to 0.5mm. The specific value needs to be selected according to the precision requirements of the molding process. The preset wall thickness difference is inversely proportional to the precision requirements of the finished product. For example, when the finished product is a thin-walled precision part, the value is 0.1mm, and when the finished product is a medium-sized conventional structural part, the value is 0.25mm.

[0092] Thin-walled precision parts include electronic connectors made of PC, while medium-sized conventional structural parts include door interior panels made of PP.

[0093] Understandably, the aforementioned preset wall thickness difference is the critical value for determining whether the base area needs to be segmented. When the difference between the maximum wall thickness and the average cavity wall thickness in the base area exceeds this value, area adjustment needs to be initiated.

[0094] It should be noted that the preset high regularity threshold, which is the critical value of regularity for determining whether the basic region needs to be adjusted, should be set based on the degree of conformity between the three-dimensional contour of the basic region and the standard geometric shape. It can be set using empirical values ​​of similarity judgment, such as 90%.

[0095] A43. Otherwise, the basic area adjustment will not be performed.

[0096] A44. When the maximum temperature difference in a certain base area exceeds the preset temperature difference, the temperature values ​​of each heat distribution area are obtained based on the heat distribution. The absolute difference between the temperature value of each heat distribution area and the average temperature of the base area is calculated. The heat distribution area whose absolute difference exceeds the preset temperature difference is taken as the newly added segmented area.

[0097] A45. When the difference between the maximum wall thickness and the average cavity wall thickness of a certain base area exceeds the preset wall thickness difference, if the absolute value of the deviation between the wall thickness at any cavity location and the average cavity wall thickness of the base area exceeds the preset wall thickness difference, then the cavity location point is used as the new segmentation point, and a segmentation boundary line is generated along the normal direction of the new segmentation point to obtain the new segmented area.

[0098] A46. When the regularity of a certain basic region is lower than the preset high regularity threshold, if the regularity of all regions within the basic region is less than the set low regularity threshold, identify the curvature change point of the three-dimensional contour corresponding to the basic region and use it as a new segmentation point. Generate a segmentation boundary line along the new segmentation point to obtain the new segmented region.

[0099] It should be noted that the above-mentioned low regularity threshold needs to reflect the significant irregularity of the three-dimensional contour of the basic area and the large deviation of the area contour from the standard geometric shape. The value range is usually set to 0.3 to 0.6, and the specific value can be selected according to the production precision requirements of automotive parts.

[0100] Understandably, the aforementioned low regularity threshold is the critical value for judging whether the base region is generally irregular in height. When the regularity of all parts within the base region is lower than this threshold, forced segmentation is required by identifying curvature abrupt change points.

[0101] A47. If the regularity of the basic region is greater than the set low regularity threshold but less than the set high regularity threshold, the region is re-segmented according to the preset segmentation rules to obtain the newly added segmented region.

[0102] A48. Combine each basic area and the newly added subdivided areas corresponding to each basic area to form each temperature control area.

[0103] Please see Figure 4 As shown, the specific process of further segmentation according to the preset segmentation rules in step A47 is as follows: A471. Identify the three-dimensional contour of the basic region to obtain the number of deformation points and the position of each deformation point.

[0104] A472. If the number of deformation points is less than or equal to the preset deformation point threshold, no new segmentation will be performed.

[0105] A473. If the number of deformation points is greater than the preset deformation point threshold, calculate the distance between each adjacent deformation point. If the maximum distance is less than or equal to the preset distance threshold, no new segmentation is performed.

[0106] A474. If the distance between adjacent deformation points is greater than a preset distance threshold, then the center position between the adjacent deformation points is used as the dividing position, and a dividing line is generated along the normal direction of the dividing position to obtain the newly added dividing region.

[0107] It should be noted that when simulating the current heat distribution in each basic region, the structural parameters of the cavity, such as wall thickness, cavity spacing, geometry, and thermal performance parameters of the injection molding material, such as thermal conductivity and specific heat capacity, can be input first. Based on Fourier's law and the principle of energy conservation, a three-dimensional heat transfer model can be constructed. The mold can be divided into several basic region grids using Moldflow simulation software. After setting the initial temperature and boundary conditions, the energy changes of each grid unit under heat conduction, convection, and radiation are iteratively calculated, and finally the temperature values ​​of each basic region are output.

[0108] The initial temperature can be set to room temperature or the residual temperature at the end of the previous process. The boundary conditions include the heating or cooling power of the cavity and the heat exchange coefficient with the outside world. The boundary conditions can be set and adjusted according to the actual production needs of automotive parts. The Moldflow simulation software is all existing technology and will not be shown or described in detail in this invention.

[0109] It should be noted that the aforementioned preset deformation point threshold is the critical value for determining whether the basic region needs to be further subdivided based on deformation points. Its setting can be based on the deformation complexity of the three-dimensional contour of the basic region, combined with the temperature control accuracy to comprehensively determine the effectiveness of temperature control in a single region. The specific value can be selected based on the contour complexity level. The contour complexity level is inversely proportional to the preset deformation point threshold value. For example, when the contour complexity level is low, such as a planar cavity region, the value is 10; when the contour complexity level is medium, such as a cavity region containing simple curvatures, the value is 7; and when the contour complexity level is high, such as a cavity region with multiple intersecting curved surfaces, the value is 3.

[0110] Understandably, the aforementioned preset distance threshold is the critical distance value for determining whether adjacent deformation points need to be separated. When the distance between adjacent deformation points exceeds this threshold, a dividing line needs to be generated with the center of the two points as the dividing position.

[0111] It should be noted that the aforementioned preset distance threshold is determined by comprehensively considering the influence of the spatial distribution of adjacent deformation points within the basic area on the uniformity of temperature control, combined with the area size and temperature control accuracy requirements. Furthermore, by analyzing the correlation between the distance between adjacent deformation points and the temperature control effect in historical segmentation cases, the maximum allowable distance that ensures temperature control consistency within the same area can be used as the preset distance threshold. This ensures that adjacent deformation points with a distance greater than this threshold need to be separated to avoid uneven temperature control due to excessive distance.

[0112] This invention combines the structural characteristics of the mold cavity with the characteristics of the injection molding material to adjust the temperature control area from three dimensions: temperature difference, wall thickness difference, and regularity. When any dimension exceeds a preset threshold, the area segmentation is automatically initiated to avoid the current temperature control area division being untargeted. This makes the temperature control area segmentation closely related to product quality, thus having clear targeting and ensuring the quality of injection molding.

[0113] S5. Based on the current temperature of each temperature control zone, the characteristics of the injection molding material, the characteristics of the mold material, and the planned cooling time, a preset temperature control model is matched to obtain a matching temperature adjustment strategy, and cooling control is performed according to the temperature adjustment strategy.

[0114] It should be noted that the aforementioned preset temperature control model is a preset temperature control strategy table based on the injection molding process parameter specifications. This preset temperature control strategy table is a structured table formed by collecting a large amount of cooling control data under various combinations of parameters, such as current temperature in different temperature control zones, characteristics of injection molding materials and mold materials, and planned cooling time. This data is combined with heat conduction simulations and actual production verification to analyze the influence of each parameter on temperature adjustment. Effective temperature adjustment strategies, such as cooling rate and spray intensity, are associated with corresponding parameter combinations. This structured table is the preset temperature control model.

[0115] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0116] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A method for temperature control in the mold area of ​​automotive parts, characterized in that, The method includes: Thermal images are generated by detecting the overall cavity of the mold using a thermal imager, and temperature information is obtained by identifying the thermal images. Based on temperature information, cavity locations that do not meet the injection molding preheating requirements are screened, and the temperature control unit in that location is activated to adjust the temperature accordingly until the injection molding preheating requirements are met before injection molding is performed. The temperature value of the cavity after the molten injection material is injected is collected in real time by the temperature sensor built into the mold. The temperature control cavity position is determined according to the current temperature value and distribution position collected by the temperature sensor and the three-dimensional spatial coordinates of the overall cavity, and the temperature of the corresponding cavity is controlled. After the injection molding process is completed and the pressure holding process is finished, the overall cavity is divided into several temperature control zones according to the structural characteristics of the overall cavity, and the current temperature is collected according to the temperature sensor built into each temperature control zone. Based on the current temperature of each temperature control zone, the characteristics of the injection molding material, the characteristics of the mold material, and the planned cooling time, a preset temperature control model is matched to obtain a matching temperature adjustment strategy, and cooling regulation is executed according to the temperature adjustment strategy.

2. The method for temperature control in the mold area of ​​automotive parts as described in claim 1, characterized in that: The process of obtaining the temperature information includes: After importing the three-dimensional model of the entire cavity and correcting the distortion of the thermal image, the SIFT algorithm is used to establish the mapping relationship between the pixels of the thermal image and the three-dimensional spatial coordinates of the entire cavity. The thermal image is identified to obtain each temperature region and the temperature value of the corresponding temperature region, and the location of the cavity to which each temperature region belongs is marked; The temperature information is composed of the temperature value corresponding to each temperature region and the location of the cavity to which it belongs.

3. The method for temperature control in the mold area of ​​automotive parts as described in claim 2, characterized in that: The step of screening cavity locations that do not meet the injection molding preheating requirements includes: Based on the location of the cavity in each temperature zone, the preset preheating target temperature value of the corresponding temperature zone is matched; Compare the temperature values ​​corresponding to each temperature zone with their preset preheating target temperature values; If the temperature value corresponding to a certain temperature zone is lower than its preset preheating standard temperature value and the difference between the temperature value and the preset preheating standard temperature value exceeds the preset allowable range, the temperature zone is marked as a cavity location that does not meet the injection molding preheating requirements.

4. The method for temperature control in the mold area of ​​automotive parts as described in claim 1, characterized in that: The steps for performing corresponding temperature control include: The cavity locations that do not meet the injection molding preheating requirements are recorded as control locations, and the number of control locations is counted. When there is only one location, the difference between the temperature value corresponding to the control position and the preset preheating target temperature value is used as the control temperature value, and the temperature control unit in the control position is started to execute the heating command based on the control temperature value. When there is more than one location, calculate the distance between each control point; If the maximum distance does not exceed the preset interval distance and the standard deviation of the controlled temperature value at each controlled position is less than the preset threshold, connect each controlled position to generate an overall controlled area; The average control temperature value at each control position is taken as the control temperature value of the overall control area, and the temperature control unit in the overall control area is activated to heat the system based on the control temperature value. If the distance between two adjacent control positions exceeds the preset interval distance, or if the distance between two adjacent control positions does not exceed the preset interval distance and the difference in the control temperature values ​​of the two adjacent control positions exceeds the preset adjacent control temperature difference, the temperature control unit in the adjacent control position is activated to heat the device based on the control temperature value. Traverse all adjacent control positions, bind and mark adjacent control positions whose distance is less than the preset interval, and form a whole control group by combining all adjacent control positions that are continuously bound and marked. The average control temperature value of each cavity position within the overall control group is taken as the control temperature value of the overall control group, and the temperature control unit of the overall control group is activated to execute the heating command based on the control temperature value.

5. The method for temperature control in the mold area of ​​automotive parts as described in claim 2, characterized in that: The method for determining the location of the temperature control cavity includes: By comparing the distribution location of each temperature sensor with the three-dimensional spatial coordinates of the overall cavity, the mapped cavity location of each temperature sensor is obtained. The preset injection threshold corresponding to the mapped cavity position is matched based on the mapped cavity position of each temperature sensor. The current temperature value collected by each temperature sensor is compared with the preset injection threshold of its mapped cavity position; If the current temperature value collected by a temperature sensor is lower than the preset injection threshold of its mapped cavity position and the difference between the temperature sensor and the preset injection threshold exceeds the preset allowable range, the mapped cavity position of the temperature sensor is marked as the temperature control cavity position.

6. The method for temperature control in the mold area of ​​automotive parts as described in claim 5, characterized in that: The specific steps for regulating the temperature of the corresponding cavity are as follows: The difference between the current temperature value of the temperature control cavity and the preset injection threshold is used as the initial cavity control temperature value. Based on the preliminary cavity control temperature value, the wall thickness of the temperature control cavity, and the characteristics of the cavity material, the target cavity control temperature value is calculated. The temperature control unit that controls the position of the cavity is activated to regulate the cavity temperature according to the target temperature value corresponding to that position.

7. The method for temperature control in the mold area of ​​automotive parts as described in claim 6, characterized in that: The calculation process for the target cavity temperature control value includes: The comprehensive compensation coefficient is calculated based on the cavity wall thickness and the thermal properties of the material. The target cavity control temperature value is obtained by correcting the initial cavity control temperature value using the comprehensive compensation coefficient.

8. The method for temperature control in the mold area of ​​automotive parts as described in claim 6, characterized in that: The method for dividing the temperature control zone includes: Mark each key node in the three-dimensional model of the overall cavity, and divide the overall cavity into several basic regions using the key nodes as the dividing endpoints and the connecting lines of the regions where the key nodes are located as the dividing lines. Based on the structural parameters of the cavity and the thermal conductivity and specific heat capacity of the injection molding material, the current heat distribution of each basic region is simulated, and the maximum temperature difference and average temperature value of the basic region are obtained according to the heat distribution. Extract the three-dimensional contours of each basic region, identify the wall thickness of each cavity location point in the corresponding basic region based on the three-dimensional contours, calculate the average cavity wall thickness of each basic region, and extract the maximum wall thickness. The base regions are adjusted based on the maximum temperature difference, average temperature value, three-dimensional profile, average and maximum cavity wall thickness, and the wall thickness at each cavity location point within each base region, to output the final temperature control regions.

9. The method for temperature control in the mold area of ​​automotive parts as described in claim 8, characterized in that: The process of adjusting the base region includes: Identify the three-dimensional contours of each basic region and statistically determine the regularity of each basic region; Determine whether any of the following conditions are triggered in each basic region. If triggered, initiate the basic region adjustment command; otherwise, do not execute the basic region adjustment. (1) The maximum temperature difference is greater than the preset temperature difference; (2) The difference between the maximum wall thickness and the average cavity wall thickness exceeds the preset wall thickness difference; (3) The regularity is lower than the preset high regularity threshold; When the maximum temperature difference in a certain base area exceeds the preset temperature difference, the temperature values ​​of each heat distribution area are obtained based on the heat distribution. The absolute difference between the temperature value of each heat distribution area and the average temperature of the base area is calculated. Heat distribution areas whose absolute difference exceeds the preset temperature difference are added as new segmented areas. When the difference between the maximum wall thickness and the average cavity wall thickness of a certain basic region exceeds the preset wall thickness difference, if the absolute value of the deviation between the wall thickness at any cavity location and the average cavity wall thickness of the basic region exceeds the preset wall thickness difference, then the cavity location point is used as the new segmentation point, and a segmentation boundary line is generated along the new segmentation point to obtain the new segmented region. When the regularity of a certain basic region is lower than the preset high regularity threshold, if the regularity of all regions within the basic region is less than the set low regularity threshold, the curvature change point of the three-dimensional contour corresponding to the basic region is identified and used as a new segmentation point. A segmentation boundary is generated along the new segmentation point to obtain the new segmented region. If the regularity of the basic region is greater than the set low regularity threshold but less than the set high regularity threshold, the region is further segmented according to the preset segmentation rules to obtain the new segmented region. Each basic area and the newly added subdivided areas corresponding to each basic area are combined to form each temperature control zone.

10. The method for temperature control in the mold area of ​​automotive parts as described in claim 9, characterized in that: The specific process of further segmenting according to the preset segmentation rules is as follows: The number of deformation points and the location of each deformation point are obtained by identifying the three-dimensional contour of the basic region. If the number of deformation points is less than or equal to the preset deformation point threshold, no new segmentation will be performed; If the number of deformation points is greater than the preset deformation point threshold, calculate the distance between each adjacent deformation point. If the maximum distance is less than or equal to the preset distance threshold, no new segmentation is performed. If the distance between adjacent deformation points is greater than a preset distance threshold, the center position between the adjacent deformation points is used as the dividing position, and a dividing line is generated along the normal direction of the dividing position to obtain a new segmented region.

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