An injection molding system and method for easy mold release

Abstract

The present application relates to injection molding technical field, disclose a kind of easy to demould injection molding system and injection molding method, by the forming surface of the core of movable mould is divided into several forming areas, and each forming area is provided with a demoulding unit, the temperature of each forming area can be accurately identified, so as to identify high holding force area, temperature pulse sequence generated by heating device can be targetedly applied, avoid weak area excessive stress, significantly reduce the demoulding damage rate.Demoulding unit includes temperature measuring device, heating device, ejector device, heat insulation layer and controllable heat conduction component, by heating device, heat insulation layer and controllable heat conduction component alternately heat and cool high holding force area, periodic thermal stress disturbance can be generated in the contact interface of finished product and the forming surface of core, actively destroy the micro adsorption of contact interface, reduce demoulding force from physical mechanism, reduce the risk of top white, strain and deformation when finished product demoulding, so that the quality of injection molding product is higher.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and in particular to an injection molding system and method that facilitates demolding. Background Technology

[0002] In injection molding of home appliances and communication equipment, product structures are becoming increasingly complex, and the number and frequency of applications of connecting structures such as snap-fit ​​devices are also increasing significantly. Home appliances such as refrigerators, washing machines, and air conditioners, communication equipment such as routers, base station housings, and 5G antennas, and consumer electronics such as mobile phones and laptops are all adopting "screwless" designs to shorten assembly time and reduce costs. This utilizes precision injection-molded snap-fit ​​and nested structures to achieve rapid assembly. Furthermore, the requirements for product appearance and texture are becoming increasingly stringent, demanding that product surfaces be free of obvious seams, screw holes, or defects. Screw holes disrupt the overall integrity and smoothness of the product's appearance, thus creating a significant demand for internal snap-fit ​​connections. Many existing home appliance panels and equipment housings employ complex irregular curved surfaces, and snap-fit ​​devices are often placed on the edges or inner sides to accommodate various complex parting surface designs. Therefore, current injection-molded products typically feature multi-curved shapes, multiple snap-fit ​​structures, and large variations in wall thickness, requiring high surface quality. However, such products are prone to defects such as whitening, tearing, and deformation during demolding.

[0003] Currently, injection molded products are typically ejected from the mold after cooling. After injection filling and holding pressure, a cooling medium is continuously circulated through the internal cooling water channels of the mold to cool the entire mold, causing the finished product to shrink. After a preset cooling time, the ejection mechanism ejects the finished product, achieving demolding. This method of overall cooling and unified ejection cannot implement differentiated demolding strategies for different structural areas of the finished product (such as the base of snap fasteners, curved transitions, and large flat areas). Difficult-to-demold areas such as snap fastener bases are treated the same as easy-to-demold areas such as flat surfaces, which can easily lead to whitening or tearing at weak points. Moreover, judging the cooling process relies on the experience of the operator to set the cooling time, which is usually conservative, resulting in a longer molding cycle; over-cooling can also cause excessive shrinkage of the finished product, which increases the demolding force. In addition, overall cooling cannot actively remove the microscopic adhesion force at the interface between the finished product and the mold, and demolding still relies on the large ejection force applied by the ejection mechanism, increasing the risk of damage to the finished product. It also lacks the ability to perceive the clamping force in each area in real time, making it impossible to accurately judge the ease or difficulty of demolding in each area before demolding, resulting in uncontrollable demolding quality. Summary of the Invention

[0004] The purpose of this invention is to provide an injection molding system and injection molding method that provides high demolding quality and easy demolding.

[0005] To achieve the above objectives, the present invention provides the following solution: In a first aspect, the present invention provides an injection molding device that is easy to demold, comprising a moving mold, a demolding system, a cooling system, and a control system. The moving mold is provided with a core, and the demolding system and the cooling system are disposed on the core. The demolding system is closer to the molding surface of the core than the cooling system. The demolding system includes several demolding units, and the molding surface of the core is divided into several molding areas. Each molding area corresponds to one demolding unit. Each demolding unit includes a temperature measuring device, a heating device, an ejection device, a heat insulation layer, and a controllable heat-conducting component. The temperature measuring device is used to detect the molding surface of the core. The temperature of the molding area is monitored by the heating device, which is used to heat the molding area. The ejector device passes through the core and is movable relative to the core. The heat insulation layer is disposed between the heating device and the cooling system. One end of the controllable heat-conducting component is connected to the cooling system, and the other end of the controllable heat-conducting component passes through the heat insulation layer and extends to the mounting location of the heating device. The controllable heat-conducting component is configured to switch between a heat-conducting connected state and a heat-conducting blocked state. The temperature measuring device, the heating device, the ejector device, and the controllable heat-conducting component are communicatively connected to the control system.

[0006] Secondly, the present invention provides an injection molding method, comprising: During the cooling stage of injection molding, the real-time temperature of each molding area on the molding surface of the moving mold core is obtained; based on the real-time temperature, geometric characteristics and material properties of each molding area, the clamping force of each molding area is estimated; and high clamping force areas are identified according to the real-time temperature, clamping force and geometric characteristics of each molding area. At the end of the cooling stage and before mold opening, a temperature pulse sequence is applied to the high clamping force area. The temperature pulse sequence includes multiple pulses arranged in chronological order. Each pulse includes a heating stage and a cooling stage. During the heating stage, the controllable heat-conducting component is in a heat-conducting blocking state, and the high clamping force area is heated by the heating device. During the cooling stage, the controllable heat-conducting component is in a heat-conducting connected state, and the heating device is turned off, allowing the residual heat of the high clamping force area to be conducted to the cooling system through the controllable heat-conducting component. After the temperature pulse sequence is applied, the mold is opened, and then the finished product is ejected by the ejection device to separate the finished product from the moving mold, thus completing the demolding.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention divides the molding surface of the moving mold core into several molding areas and provides a demolding unit for each molding area. This allows for precise temperature identification of each molding area, thereby identifying high-clamping-force areas. The heating device can then apply a targeted temperature pulse sequence, preventing excessive stress on weak areas and significantly reducing demolding damage. The demolding unit includes a temperature measuring device, a heating device, an ejection device, a heat insulation layer, and a controllable heat-conducting component. The heating device, heat insulation layer, and controllable heat-conducting component alternately heat and cool the high-clamping-force areas, generating periodic thermal stress disturbances at the contact interface between the finished product and the molding surface of the core. This actively disrupts the microscopic adsorption at the contact interface, reducing demolding force from a physical mechanism, rather than relying on overall softening or full shrinkage of the finished product. Furthermore, the invention employs a low-speed, high-speed, and medium-speed progressive ejection when ejecting the finished product. The high-clamping-force areas are first separated with a small stroke before the entire finished product is demolded, ensuring balanced stress throughout the demolding process and further reducing the risks of whitening, tearing, and deformation. In addition, the pulse parameters of the temperature pulse sequence applied to the high clamping force area are output by the pulse optimization model. The pulse optimization model will be updated according to the production record and can automatically iterate and optimize the pulse parameters, so that the injection molding equipment becomes more and more accurate with the progress of production batches. It can also adapt to changes such as mold aging through time decay weight, so that the output pulse is better. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the injection molding system according to an embodiment of the present invention; Figure 2 yes Figure 1 Enlarged view at point A; Figure 3 This is a flowchart of the injection molding method according to an embodiment of the present invention.

[0009] In the figure, 1-moving mold; 2-core; 3-cooling system; 4-temperature measuring device; 5-heating device; 6-ejection device; 7-heat insulation layer; 8-controllable heat conduction component; 801-first heat conduction component; 802-second heat conduction component; 803-movable heat conduction component; 804-electromagnetic coil; 805-reset spring. Detailed Implementation

[0010] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0011] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0012] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0013] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0014] Example 1 like Figure 1 and Figure 2As shown, a preferred embodiment of the present invention provides an easy-to-demold injection molding device, including a moving mold 1, a demolding system, a cooling system 3, and a control system. The moving mold 1 has a core 2. The demolding system and the cooling system 3 are located on the core 2. The demolding system is closer to the molding surface of the core 2 than the cooling system 3. The demolding system includes several demolding units. The molding surface of the core 2 is divided into several molding areas, and one molding area corresponds to one demolding unit. The demolding unit includes a temperature measuring device 4, a heating device 5, an ejection device 6, a heat insulation layer 7, and a controllable heat-conducting component 8. The temperature measuring device 4... The heating device 5 is used to heat the molding area for detecting the temperature of the molding area. The ejector device 6 passes through the core 2 and can move relative to the core 2. The heat insulation layer 7 is located between the heating device 5 and the cooling system 3. One end of the controllable heat-conducting component 8 is connected to the cooling system 3, and the other end of the controllable heat-conducting component 8 passes through the heat insulation layer 7 and extends to the installation location of the heating device 5. The controllable heat-conducting component 8 is configured to switch between a heat-conducting connected state and a heat-conducting blocked state. The temperature measuring device 4, the heating device 5, the ejector device 6, and the controllable heat-conducting component 8 are communicatively connected to the control system. In this embodiment, by dividing the surface of the core 2 of the moving mold 1 into several molding areas and setting a demolding unit for each molding area, the temperature of each molding area can be accurately identified, thereby identifying areas with high clamping force. This allows the temperature pulse sequence generated by the heating device 5 to be applied in a targeted manner, avoiding excessive force on weak areas and significantly reducing the demolding damage rate. The demolding unit includes a temperature measuring device 4, a heating device 5, an ejection device 6, a heat insulation layer 7, and a controllable heat-conducting component 8. The heating device 5, heat insulation layer 7, and controllable heat-conducting component 8 alternately heat and cool the high-clamping force area, generating periodic thermal stress disturbances at the contact interface between the finished product and the molding surface of the core 2. This actively disrupts the microscopic adsorption at the contact interface, reducing the demolding force from a physical mechanism, rather than relying on the overall softening or full shrinkage of the finished product. Furthermore, the speed and stroke of the ejection device 6 can be controlled by the control system, employing low-speed, high-speed, and medium-speed progressive ejection. The high-clamping force area is first separated with a small stroke, and then the entire finished product is demolded, ensuring balanced force distribution throughout the demolding process and further reducing the risks of whitening, tearing, and deformation.

[0015] Specifically, the controllable heat-conducting component 8 in this embodiment includes a first heat-conducting element 801, a second heat-conducting element 802, a movable heat-conducting element 803, and a movable driving mechanism. The first heat-conducting element 801 is connected to the cooling system 3. The second heat-conducting element 802 passes through the heat insulation layer 7 and extends to the mounting location of the heating device 5. The movable heat-conducting element 803 is located between the first heat-conducting element 801 and the second heat-conducting element 802. The movable driving mechanism is connected to the movable heat-conducting element 803 and drives the movable heat-conducting element 803 to move relative to the core 2. The controllable heat-conducting component 8 is configured to switch between a heat-conducting connected state and a heat-conducting blocked state. In the heat-conducting connected state, the controllable heat-conducting component 8 establishes a heat conduction path from the heating device 5 to the cooling system 3. In the heat-conducting blocked state, the controllable heat-conducting component 8 cuts off the heat conduction path. In this embodiment, the movable heat-conducting component 803 is moved by a movable drive mechanism. When the movable heat-conducting component 803 moves to the first position, it is in contact with both the first heat-conducting component 801 and the second heat-conducting component 802, entering a heat-conducting communication state. The residual heat of the molding area is conducted to the cooling system 3 through the second heat-conducting component 802, the movable heat-conducting component 803, and the first heat-conducting component 801 to cool the molding area. When the movable heat-conducting component 803 moves to the second position, it is not in contact with either the first heat-conducting component 801 or the second heat-conducting component 802, entering a heat-conducting blocking state. The residual heat of the molding area cannot be conducted to the cooling system 3, thereby preventing the heat generated by the heating device 5 on the molding area from being carried away. In addition, there is a heat insulation layer 7 for heat insulation, so that the heating device 5 can heat the high-clamping force area in a shorter time and with less energy consumption. After the injection molding system in this embodiment has completed the pressure holding process, during the cooling stage, the cooling system 3 continuously cools the system. The heat insulation layer 7 and the controllable heat conduction component 8 are provided to prevent the heat generated by the heating device 5 when heating the high clamping force area from being carried away, and also to prevent the heat generated by the heating device 5 from raising the temperature of the cooling system 3 and affecting the cooling effect of the non-high clamping force area.

[0016] The movable drive mechanism of this embodiment includes an electromagnetic coil 804 and a return spring 805. The core 2 is provided with an installation channel perpendicular to the straight line where the first heat-conducting element 801 and the second heat-conducting element 802 are located. The electromagnetic coil 804 and the return spring 805 are respectively located at both ends of the installation channel, so that the electromagnetic coil 804 and the return spring 805 are located on both sides of the first heat-conducting element 801. The movable heat-conducting element 803 is installed at the end of the return spring 805 near the electromagnetic coil 804. The electromagnetic coil 804 is electrically connected to the control system. In the thermally blocked state, the electromagnetic coil 804 is energized, and the movable heat-conducting component 803 moves along the direction close to the electromagnetic coil 804 until it is attracted to the electromagnetic coil 804. The return spring 805 is stretched, thereby causing the movable heat-conducting component 803 to move away. At this time, the heating device 5 can heat the high clamping force area. In the thermally connected state, the electromagnetic coil 804 is de-energized, the return spring 805 returns to its original position, and the movable heat-conducting component 803 is reset. The heat conduction of the second heat-conducting component 802, the movable heat-conducting component 803 and the first heat-conducting component 801 is connected, and the molding area is cooled.

[0017] Optionally, the cooling system 3 in this embodiment includes a cooling water channel disposed on the core 2. By introducing cooling water or other cooling media into the cooling water channel, the excess heat on the moving mold 1 can be dissipated, achieving heat dissipation and cooling. The temperature measuring device 4 includes multiple thermocouples disposed in the core 2, and the thermocouples are electrically connected to the control system. The heating device 5 includes an electric heating element embedded in the core 2, and the electric heating element is electrically connected to the control system. In this embodiment, multiple thermocouples are arranged around the electric heating element, which is located at the center of the molding area. The thermocouples and the electric heating element are staggered, so that the thermocouples measure the true temperature of the molding surface and do not produce falsely high readings due to the heating element's own heating, thus avoiding mutual obstruction of the heat transfer path. The pressing device includes a hydraulic cylinder and multiple ejector pins. The ejector pins are mounted on the core 2. The output end of the hydraulic cylinder is connected to the ejector pin. The control system is connected to the hydraulic cylinder control system, which controls the start, stop, and movement stroke of the ejector pins by controlling the hydraulic cylinder. A displacement detection device is installed on each ejector pin to detect its actual displacement, thus achieving closed-loop control. The displacement detection device uses a displacement sensor. In this embodiment, the heat insulation layer 7 is a glass fiber reinforced thermosetting composite material layer.

[0018] Furthermore, in this embodiment, the ejector device 6 is equipped with a pressure detection device at one end of the molding surface of the core 2. The end face of the ejector device 6 is flush with the molding surface of the core 2. By setting a pressure detection device on the ejector device 6, the local contact pressure between the finished product and the molding surface of the core 2 can be measured. This allows for the estimation of the clamping force in the molding area based on the measured temperature and pressure, making the clamping force assessment more accurate. Moreover, during the demolding stage, when the finished product is ejected by the ejector device 6, the pressure detection device can detect the pressure on the ejector device 6. If the pressure measured by the pressure detection device exceeds the set safety pressure threshold, it means that the clamping force in the molding area may be too large, posing a risk of damaging the finished product. The control system will immediately stop ejection and issue an alarm to prevent batch scrapping accidents. In this embodiment, the pressure sensor is a piezoelectric thin film sensor, which is electrically connected to the control system.

[0019] Example 2 like Figure 3 As shown, a preferred embodiment of the injection molding method of the present invention, based on the injection molding equipment of Embodiment 1, includes: During the cooling stage of injection molding, the real-time temperature of each molding area on the molding surface of the moving mold core is obtained; based on the real-time temperature, geometric characteristics and material properties of each molding area, the clamping force of each molding area is estimated; and high clamping force areas are identified according to the real-time temperature, clamping force and geometric characteristics of each molding area. At the end of the cooling stage and before mold opening, a temperature pulse sequence is applied to the high clamping force area. The temperature pulse sequence includes multiple pulses arranged in chronological order. Each pulse includes a heating stage and a cooling stage. During the heating stage, the controllable heat-conducting component is in a heat-conducting blocking state, and the high clamping force area is heated by the heating device. During the cooling stage, the controllable heat-conducting component is in a heat-conducting connected state, and the heating device is turned off, allowing the residual heat of the high clamping force area to be conducted to the cooling system through the controllable heat-conducting component. After the temperature pulse sequence is applied, the mold is opened, and then the finished product is ejected by the ejection device to separate the finished product from the moving mold, thus completing the demolding.

[0020] During injection molding, the clamping force of the finished product on the core of the moving mold is mainly caused by thermal shrinkage. When the high-temperature injection material enters the cavity formed by the closing of the moving and fixed molds, the plastic undergoes thermal shrinkage as the temperature drops, thus generating a clamping force on the core. Therefore, this embodiment estimates the clamping force of each molding zone based on the initial temperature, geometric characteristics, and material properties of the injection material. Based on the initial temperature, clamping force, and geometric characteristics of each molding zone, high-clamping-force zones are identified. At the end of the cooling stage and before mold opening, a series of temperature pulses are applied to these high-clamping-force zones, with heating and cooling occurring in each pulse. This process is repeated several times, causing the finished product and the molding surface to undergo periodic stress disturbance, achieving gradual dissociation and adhesion. For non-high-clamping-force zones, no pulses are applied; only normal cooling is maintained.

[0021] In one specific embodiment, the pulse parameters of the temperature pulse sequence are preset, specifically: the number of pulse cycles of the temperature pulse sequence is 3 to 8 times, the heating duration of a single pulse is 1 to 5 seconds, the cooling time is 2 to 8 seconds, the heating amplitude of a single pulse is 3 to 15°C, and the application time of the entire temperature pulse sequence is controlled within 10 to 60 seconds.

[0022] During the cooling phase, the temperature measuring device in this embodiment collects the real-time temperature of each molding area at a preset sampling frequency. Based on the real-time temperature, geometric characteristics, and material properties of the injection molding material of each molding area, the clamping force of each molding area is estimated. Simultaneously, based on the real-time temperature, clamping force, and geometric characteristics of each molding area, areas with high clamping force are identified. From the beginning of the cooling phase to the end of the cold-cutting phase, the temperature of each molding area is monitored in real-time by the temperature measuring device. Clamping force is estimated each time a new set of temperature data is collected. At the end of the cooling phase, areas with high clamping force are identified based on the latest real-time temperature, the latest estimated clamping force, and geometric characteristics.

[0023] This embodiment applies a series of temperature pulses to the high-clamping area at the end of the cooling stage and before mold opening. The end of the cooling stage, before mold opening, is determined when the real-time temperature measured in all molding areas has dropped below the heat distortion temperature (HDT) of the injection molding material. For example, if the injection molding material is ABS (Acrylonitrile Butadiene Styrene), whose HDT is approximately 105°C, the end of the cooling stage is determined when the real-time temperature measured by the temperature measuring device in all molding areas is below 105°C; or the end of the cooling stage is determined when the time elapsed in the cooling stage reaches a preset percentage of the total cooling time. Optionally, the preset percentage is 70%–80%. For example, if the preset total cooling time is 30 seconds and the preset percentage is 80%, then the end of the cooling stage begins at the 24th second. In this embodiment, the start time of the cooling stage is calculated from the end of the holding pressure and the start of the cooling timer.

[0024] Specifically, the estimation of the clamping force of each molding zone based on the real-time temperature, geometric features, and material properties of the injection molding material of each molding zone includes: The appropriate geometric coefficients are selected based on the complexity of the geometric features of each forming region; Obtain the effective contact area between each molding area and the finished product; The material properties of the injection molding material are obtained, including the coefficient of thermal expansion, solidification temperature, and elastic modulus. The shrinkage stress of each molding region is obtained based on the real-time temperature of each molding region, the coefficient of thermal expansion, the solidification temperature, and the elastic modulus. The clamping force of each molding area is obtained based on the geometric coefficient, the effective contact area, and the shrinkage stress of each molding area.

[0025] The clamping force of each molding area in this embodiment is estimated using the following formula:

[0026] in, For the force of holding; For the first Secondary clamping force prediction; The real-time temperature measured by the temperature measuring device in the forming area; These are the geometric coefficients corresponding to the forming area; For injection molding materials at temperature The coefficient of thermal expansion at that time; The effective solidification temperature of the injection molding material; This refers to the effective contact area of ​​the molding region; For injection molding materials at temperature The elastic modulus at that time.

[0027] coefficient of thermal expansion It is an inherent property of injection molding materials. Represents the temperature difference from the solidification of the injection-molded material to the current sampling time, through The shrinkage strain generated during this cooling process can be obtained. This shrinkage strain is then compared with the elastic modulus. Multiplying these yields the stress caused by thermal contraction; then, the stress is multiplied by the effective contact area. Multiplying these gives the total stress in the formed area, which is then calculated using geometric coefficients. Make corrections to estimate the clamping force of each forming area.

[0028] Based on the complexity of the geometric features of the forming area, the forming area is divided into a snap-fit ​​area, a curved transition area, and a planar area. The geometric coefficients for the snap-fit ​​area are 1.2–1.5, for the curved transition area they are 0.8–1.2, and for the planar area they are 0.5–0.8. In this embodiment, the geometric coefficient for the snap-fit ​​area is 1.3, for the curved transition area it is 1.0, and for the planar area it is 0.6.

[0029] To determine whether a molding area is a snap-fit ​​area, a curved transition area, or a planar area, this embodiment uses CAD / CAE software for analysis. Utilizing the geometric feature information integrated into the CAD model, each molding area is classified as a snap-fit ​​area, a curved transition area, or a planar area based on the complexity of its geometric features. Specifically, the 3D CAD model of the workpiece to be injection molded is imported, and the set of molding surfaces of the moving mold core is determined according to the mold opening direction. The set of molding surfaces is traversed, and based on curvature continuity and topological characteristics, the molding surfaces are divided into snap-fit ​​areas, curved transition areas, and planar areas. Finite element analysis is performed on each molding area using CAE. For the snap-fit ​​area, transient structural mechanics analysis is performed to calculate the elastic deformation and stress concentration factor during demolding. For the curved transition area, injection flow simulation analysis is performed to calculate the shear rate and pressure loss gradient of the melt flowing through this area. For the planar area, heat conduction analysis is performed to calculate the temperature field of all nodes in the planar area. The CAE analysis results of each molding area are mapped back to the CAD model to generate a visual assessment report containing area attribute labels and physical risk values. The molding areas are then reclassified based on the visual assessment report.

[0030] The process of traversing the set of forming surfaces involves dividing the forming surfaces into snap-fit ​​areas, curved transition areas, and planar areas based on curvature continuity and topological characteristics, including: Extract the undercut features from the surface of the 3D CAD model of the workpiece to be injection molded. The undercut features include depth and cantilever length. If the ratio of the undercut depth to the cantilever length is greater than or equal to the tangent function value of the allowable elastic angle of the material, it is marked as a snap-fit ​​area. In this embodiment, the undercut is detected by ray projection method. If an undercut is detected, the features of the undercut are extracted. Calculate the Gaussian curvature and average curvature of the formed surface. If the rate of change of curvature in the formed area exceeds a preset threshold, and the formed area connects two geometric surfaces with different normal vectors, it is marked as a surface transition area. Calculate the angle between the normal vector of each forming area and the mold opening direction. If the angle is less than the preset angle threshold and the curvature is close to zero, it is marked as a planar area.

[0031] The process of re-dividing the formed area based on the visual evaluation report includes: For the curved transition zone, the curved transition zone is further divided according to the shear rate change and pressure loss gradient; specifically, the area in the curved transition zone where the shear rate exceeds a preset shear threshold and the area exceeds a preset area threshold is independently defined as a forming area, and the area in the curved transition zone where the pressure loss gradient exceeds a preset gradient threshold and the area exceeds a preset area threshold is independently defined as a forming area; thus, a curved transition zone can be further divided into multiple forming areas; in this embodiment, the preset area threshold is set to ensure that the area of ​​each forming area is the minimum value, preventing the area of ​​the forming area from being too small to facilitate the setting of the demolding unit; For a planar area, the planar area is further divided according to the temperature field of all nodes in the planar area. Specifically, the global average temperature of the planar area is calculated based on the temperature field of all nodes in the planar area. The temperature difference between any node and the global average temperature is calculated. Areas with a temperature difference exceeding a preset temperature difference threshold and an area exceeding a preset area threshold are independently defined as forming areas. Thus, a planar area can be further divided into multiple forming areas.

[0032] In summary, the forming surface can be divided into multiple forming areas, and each forming area can be labeled with a corresponding area attribute label. The area attribute labels include snap-fit ​​areas, curved transition areas, and flat areas, and then the corresponding geometric coefficients can be selected for each forming area.

[0033] Furthermore, the estimation of the clamping force of each molding zone based on the real-time temperature, geometric features, and material properties of the injection molding material of each molding zone includes: Based on the real-time temperature, geometric features, and material properties of the injection molding material of each molding zone, the initial estimated clamping force of each molding zone is obtained. Obtain the local contact pressure between each molding area and the finished product; The clamping force of each molding area is obtained based on the initial estimated clamping force of each molding area and the local contact pressure between each molding area and the finished product.

[0034] This embodiment also uses local contact pressure to estimate the clamping force, which makes the clamping force estimation more accurate. A pressure detection device set at the end of the ejector device that is flush with the molding surface of the core measures the local contact pressure between each molding area and the finished product, and integrates the local contact pressure with the initial estimated clamping force to obtain a more accurate clamping force.

[0035] The step of obtaining the clamping force of each molding area based on the initial estimated clamping force of each molding area and the local contact pressure between each molding area and the finished product includes: The initial estimated clamping force of each molding area is combined with the local contact pressure between each molding area and the finished product to obtain the clamping force of each molding area. The combined expression is as follows:

[0036] in, For the initial estimated clamping force; The conversion coefficient between contact pressure and clamping force. Determined through offline calibration; This is the maximum value among the peak pressures detected by all pressure detection devices within the molding area; and Here, are the weighting coefficients, ,and As the forming area was identified as a high-clamping-force area and the temperature pulse sequence was successfully executed, the cumulative number of effective pressure data collected during the ejection process of the finished product by the ejection device gradually increased.

[0037] Specifically, weighting coefficients As the cumulative number increases, the cumulative number must meet all of the following conditions: (1) In the production cycle, the molding area is identified as a high clamping force area; (2) A temperature pulse sequence is applied to the molding area, and the temperature pulse sequence is normal and uninterrupted; (3) When the ejector device corresponding to the molding area ejects the finished product in the final demolding, the pressure detection device on the ejector device reads normally and the data is valid; (4) There is no abnormal demolding, that is, the surface quality of the finished product after demolding is qualified, and there are no defects such as whitening or tearing. The injection molding equipment in this embodiment is equipped with a vision inspection system, which is connected to the control system. After the mold is opened and the finished product is ejected and falls, the vision inspection system takes pictures of the finished product from multiple angles and transmits the pictures to the control system. The control system uses an image processing algorithm to determine the defects. The vision inspection system in this embodiment uses an industrial camera. Therefore, only when the above four conditions are met is it counted as one cumulative number. This embodiment sets multiple gradually increasing cumulative thresholds for the cumulative number. When the cumulative number reaches the preset cumulative threshold, the weight coefficient is adjusted. Adjust to the size corresponding to this cumulative threshold. Weighting coefficient. The initial value is 0.2 to 0.4, and the weighting coefficient in this embodiment is... The initial value is 0.2, and the cumulative thresholds for the number of times are 20, 50, and 100. When the cumulative number of times reaches 20, the weight coefficient is adjusted. Adjust to 0.3; when the cumulative number of times reaches 50, the weighting coefficient will be adjusted. Adjust to 0.4; when the cumulative number of times reaches 100, the weighting coefficient will be adjusted. The weighting coefficient is adjusted to 0.5. This embodiment will use this weighting coefficient. It is set to be adjustable. In the initial stage, the conversion coefficients need to be calibrated offline before the first use. However, initial measurements can be inaccurate due to factors such as instantaneous impacts and sensor drift. Therefore, in the initial stage, temperature is the primary factor, with pressure as a secondary factor. As the number of measurements increases, the pressure detection device becomes more stable and reliable, thus increasing the weight of pressure in the estimation of clamping force. It should be noted that the weighting coefficient... This is the cumulative number of batches under the current mold and injection material combination. When the mold or injection material changes, the weighting coefficient is adjusted. Reset according to preset rules, which include: weighting coefficients when the mold is changed. Reset to initial value; if only the injection molding material changes, the weighting coefficient... The weighting coefficient corresponding to the median of the cumulative threshold is used for regression. If the cumulative threshold is an even number, the weight coefficient corresponding to the smaller of the two cumulative thresholds at the middle position is taken. If the mold and injection molding material remain unchanged, but the downtime exceeds the preset number of days, the weighting coefficient will be adjusted. The calculation formula is as follows: The value is reduced by a preset ratio based on the current value. ,in, For the new weighting coefficients , Weighting coefficients before shutdown Current value, This is the daily attenuation coefficient. The value ranges from 0.005 to 0.02 in this embodiment. =0.01, This represents the number of days the machine was down.

[0038] In one specific embodiment, identifying high-clamping-force areas based on the real-time temperature, clamping force, and geometric characteristics of each molding area includes: The forming area is a high-clamping-force area if it meets one of the following conditions: The clamping force in the forming area is greater than the preset clamping force threshold. The ratio of the clamping force of the forming area to the average clamping force of all forming areas is greater than a preset ratio; The temperature difference between the real-time temperature of the molding area and the solidification temperature of the injection molding material is greater than the preset temperature difference. The geometric features of the formed area are complex.

[0039] The geometric features of the forming area are complex features, meaning that if the forming area is a snap-fit ​​area, then the forming area is directly determined to be a high-clamping area.

[0040] In addition, the process of opening the mold after the temperature pulse sequence is applied, and then ejecting the finished product through the ejection device to separate the finished product from the moving mold and complete the demolding includes: The ejection device in the high clamping force area ejects the first stroke at a low speed; The ejection device drives all forming areas to eject synchronously at high speed during the second stroke. The ejection device that drives all forming areas synchronously ejects the third stroke at medium speed.

[0041] In this embodiment, during demolding, the ejection device is driven to eject the finished product in stages, allowing the high-clamping-force area to detach first with a small stroke, and then the entire finished product to detach evenly. This ensures that the injection-molded product is subjected to balanced force throughout the demolding process, further reducing the risk of whitening, tearing, and deformation. The first stroke uses a low speed to allow the ejection device to smoothly contact the finished product, avoiding whitening or dents on the surface due to instantaneous impact. The second stroke uses a high speed to quickly eject the finished product, shortening the production cycle and improving efficiency. The third stroke uses a low speed to decelerate as the finished product is about to completely leave the mold, preventing damage from inertial impacts to the robot arm or other components.

[0042] Specifically, the ejection device that drives all forming areas to synchronously eject the second stroke at high speed includes: The criteria for determining whether a high-clamping force area has disengaged include: the clamping force of the high-clamping force area after the first stroke of the ejection device decreases by no less than 30% compared to before ejection; the reading deviation of the displacement detection device of the ejection device in the high-clamping force area does not exceed 0.1mm; and the output force of the drive device corresponding to the ejection device in the high-clamping force area drops by no less than 20% after reaching the initial peak value. If the judgment rules are met simultaneously, then the ejection devices of all forming areas are driven to eject the second stroke at high speed and synchronously. If the judgment rule is not met, a temperature pulse sequence is applied again and the ejection device in the high clamping force area is driven again to eject the first stroke at a low speed. If the judgment rule is still not met after repeating the temperature pulse sequence and the first stroke ejection, an alarm is triggered. At this time, there is a risk of unqualified finished product and damage to the mold, which must be handled manually.

[0043] The reading deviation of the displacement detection device of the ejection device in the high clamping force area does not exceed 0.1mm, which means that the difference between the actual displacement detected by the displacement detection device on the ejection device and the displacement command issued by the control system does not exceed 0.1mm.

[0044] The ejection device that drives all forming areas to eject synchronously at high speed during the second stroke also includes: The ejection device in the non-high clamping force area ejects at a low speed to the current position of the ejection device in the high clamping force area. Once the readings of the displacement detection devices in all forming areas are consistent, the ejection devices in all forming areas are driven to eject the second stroke at high speed and synchronously.

[0045] In one specific embodiment, the first stroke is 20% to 40% of the total ejection stroke, and after the second ejection stroke, the cumulative stroke of the ejection device is 80% of the total ejection stroke. The low speed is 1 to 3 mm / s, the medium speed is 3 to 8 mm / s, and the high speed is 8 to 20 mm / s.

[0046] Furthermore, the injection molding method of this embodiment also includes: Collect demolding process parameters for each injection molding cycle, including the peak demolding force of each ejection device and the surface quality grade of the finished product after demolding; The initial temperature, pulse parameters, and corresponding demolding process parameters of each molding zone in each injection molding cycle are treated as a production record and stored in the historical database. When the number of accumulated production records reaches the preset pulse optimization model update threshold, the pulse optimization model is updated with the initial temperature and pulse parameters of each molding zone as input features and a comprehensive optimization objective constructed with the peak demolding force and surface quality level as output. The updated pulse optimization model outputs the pulse parameters for the next injection molding cycle. The pulse parameters include the temperature rise amplitude and the number of pulse cycles. The pulse optimization model outputs corresponding pulse parameters based on the initial temperature applied by the temperature pulse sequence of each forming region.

[0047] In another specific embodiment, the pulse parameters of the temperature pulse sequence are not fixed, allowing the pulse parameters to be iteratively optimized. As production progresses, the pulse parameters can be automatically adjusted to continuously ensure demolding quality by adapting to mold wear.

[0048] During the first production run, initial pulse parameters need to be determined. In this embodiment, mold flow analysis is performed on the injection molding process to obtain a detailed temperature field cloud map of the core at the end of the cooling stage. The starting temperature of each molding zone is set based on this temperature field cloud map, and the corresponding initial pulse parameters are then set according to the starting temperature of each molding zone. The starting temperature mentioned in this embodiment refers to the temperature of the molding zone at the end of the cooling stage under normal production cycle time, just before the temperature pulse sequence is introduced. Since there are no production records in the historical database before the first production run, initial pulse parameters cannot be provided. Therefore, initial preset values ​​need to be set for the pulse parameters to obtain these initial pulse parameters. Only when there are sufficient production records in the historical database can the pulse optimization model be trained and optimized, allowing the use of the pulse parameters output by the pulse optimization model. Therefore, the pulse parameters are determined based on the initial preset values ​​or the pulse optimization model.

[0049] In this embodiment, the peak demolding force of each ejector device is measured during the demolding process by a pressure detection device installed at the end of the ejector device flush with the molding surface of the core. That is, it represents the maximum pressure detected during the ejection process. The surface quality grade of the demolded product is output by the vision inspection system and control system of the injection molding equipment. The vision inspection system on the injection molding equipment takes multi-angle photos of the product and transmits the images to the control system. The control system uses image processing algorithms to determine defects and outputs the corresponding surface quality grade of the demolded product.

[0050] The pulse optimization model is updated by taking the initial temperature and pulse parameters applied in the temperature pulse sequence of each molding area as input features, and a comprehensive optimization objective constructed with the peak demolding force and surface quality level as output, including: For each production record, calculate the comprehensive cost function, which is expressed as follows:

[0051] in, This is the maximum value among the peak ejection forces of the ejection devices in all molding zones; This is a preset demolding force reference value; For surface quality penalty items, the value is 0 when the surface quality grade of the finished product after demolding is no defect, C1 when it is slight whitening, and C2 when it is obvious defect, and C2 > C1 > 0. The value of C1 is 0.3 to 0.7, and the value of C2 is 1.0 to 2.0. and These are the weighting coefficients. ,and > ; The impulse optimization model minimizes the comprehensive cost function. To optimize the objective.

[0052] The preset demolding force reference value in this embodiment This data is obtained by collecting "golden batch" data during the trial molding stage. A "golden batch" refers to a specific batch in which product quality fully meets or exceeds standards during production, and the production process is extremely stable. For example, if 50 completely qualified products are produced consecutively, these 50 products are considered a "golden batch." The system automatically collects the maximum value of the peak release force measured by each ejection device during these 50 injection molding cycles, and then takes the average value as the reference benchmark value for release force. .

[0053] Specifically, the pulse optimization model in this embodiment is a Bayesian optimization model. The pulse optimization model uses a Gaussian process regression model as a surrogate model to search for recommended pulse parameters in the pulse parameter space that minimize the overall cost function, aiming to improve the acquisition function. This embodiment's pulse optimization model, employing a Bayesian optimization model, is suitable for the small amount of data in injection molding production, prevents overfitting, and has a small iterative computational load, allowing it to run in real-time on injection molding machine PLCs or edge computing devices.

[0054] During operation, upon determining that the cooling phase is nearing its end and preparing to implement the temperature pulse sequence, a temperature measuring device synchronously samples the real-time temperature of all forming areas to obtain real-time input data. Based on this data, the clamping force of each forming area is estimated, and high-clamping-force areas are identified. The real-time temperature of these high-clamping-force areas is then input into the pulse optimization model. This model searches for candidate parameter combinations within the pulse parameter space. A Gaussian process regression model iterates through all candidate parameter combinations, outputting the corresponding predicted mean and predicted variance for each combination. The predicted mean is the comprehensive cost function value. The expected improvement acquisition function calculates the expected improvement score for each candidate parameter combination based on the predicted mean and predicted variance, and outputs the candidate parameter combination with the highest expected improvement score as the final pulse parameter output by the model.

[0055] The pulse parameter space is determined in the following way: Obtain the heat distortion temperature (HDT) of the injection molding material used in the current injection molding cycle and the expected initial temperature range of the mold. and the available duration of the cooldown window. ; The heating amplitude is determined based on the heat distortion temperature and the expected starting temperature range. Safety Limit , and set Safety lower limit The temperature is 2-3℃; Based on the available time and the duration of a single pulse cycle Determine the safe upper limit of the number of pulse cycles N. ,in Provide a floor function and set a safe lower bound for N. 1 to 2 times; Therefore, the pulse parameter space is constructed as follows: , ; The pulse optimization model searches for recommended pulse parameters within the pulse parameter space to obtain several candidate parameter combinations.

[0056] Furthermore, when the number of accumulated production records reaches a preset pulse optimization model update threshold, the pulse optimization model is updated using the initial temperature of the applied temperature pulse sequence in each molding area and the pulse parameters used as input features, and a comprehensive optimization objective constructed using the peak demolding force and surface quality level as output. This update includes: When the number of accumulated production records reaches the preset pulse optimization model update threshold, a training dataset is constructed using the latest production records of the preset threshold number; a comprehensive cost function is calculated for each production record in the training dataset as the label value of that production record, and the comprehensive cost function is constructed based on the peak demolding force and surface quality level; The pulse optimization model is trained by using the initial temperature and pulse parameters applied to the temperature pulse sequence of each forming area in each production record as input features and the label value of the production record as output. After training, the updated pulse optimization model is obtained. Specifically, when training the impulse optimization model, time decay weights are assigned to the production records in the training dataset, so that the weight of recent production records is greater than that of distant production records.

[0057] This embodiment employs time-decay weights during model training, giving higher weights to recent records and lower weights to older records. Higher weights mean the model will prioritize recent data, minimizing their prediction errors. This allows the model to automatically forget outdated, no longer applicable early experiences, accurately matching the current state of the model.

[0058] In summary, this invention provides an injection molding device that divides the molding surface of the moving mold core into several molding areas and provides a demolding unit for each molding area. This allows for precise temperature identification of each molding area, thereby identifying areas with high clamping forces. The heating device can then apply a targeted temperature pulse sequence, preventing excessive stress on weak areas and significantly reducing demolding damage. The demolding unit includes a temperature measuring device, a heating device, an ejection device, a heat insulation layer, and a controllable heat-conducting component. By alternately heating and cooling the high clamping force areas through the heating device, heat insulation layer, and controllable heat-conducting component, periodic thermal stress disturbances are generated at the contact interface between the finished product and the molding surface of the core. Through repeated small-scale heating and cooling, the microscopic adsorption at the contact interface is actively disrupted, reducing the demolding force from a physical mechanism, rather than relying on the overall softening or full shrinkage of the finished product. This invention also employs a gradual ejection process using low, high, and medium speeds during the ejection of the finished product. This first separates the high-clamping-force area with a small stroke, and then the entire finished product is demolded. This ensures balanced force distribution throughout the demolding process, further reducing the risks of whitening, tearing, and deformation. Furthermore, the pulse parameters for the temperature pulse sequence applied to the high-clamping-force area are output by a pulse optimization model. This model is updated based on production records and can automatically iterate and optimize the pulse parameters, making the injection molding equipment increasingly accurate with each production batch. It can also adapt to changes such as mold aging through time decay weights, resulting in even better output pulses.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. An injection molding machine that facilitates demolding, characterized in that, The system includes a moving mold, a demolding system, a cooling system, and a control system. The moving mold has a core. The demolding system and the cooling system are located on the core. The demolding system is closer to the molding surface of the core than the cooling system. The demolding system includes several demolding units. The molding surface of the core is divided into several molding areas, and each molding area corresponds to one demolding unit. Each demolding unit includes a temperature measuring device, a heating device, an ejection device, a heat insulation layer, and a controllable heat-conducting component. The temperature measuring device is used to detect the temperature of the molding area. The heating... The device is used to heat the molding area. The ejector device passes through the core and is movable relative to the core. The heat insulation layer is disposed between the heating device and the cooling system. One end of the controllable heat-conducting component is connected to the cooling system, and the other end of the controllable heat-conducting component passes through the heat insulation layer and extends to the mounting location of the heating device. The controllable heat-conducting component is configured to switch between a heat-conducting connected state and a heat-conducting blocked state. The temperature measuring device, the heating device, the ejector device, the controllable heat-conducting component, and the control system are communicatively connected.

2. The injection molding equipment according to claim 1, characterized in that, The controllable heat-conducting component includes a first heat-conducting element, a second heat-conducting element, a movable heat-conducting element, and a movable driving mechanism. The first heat-conducting element is connected to the cooling system. The second heat-conducting element passes through the insulation layer and extends to the mounting location of the heating device. The movable heat-conducting element is located between the first heat-conducting element and the second heat-conducting element. The movable driving mechanism is connected to the movable heat-conducting element and drives the movable heat-conducting element to move relative to the core.

3. The injection molding equipment according to claim 1, characterized in that, The ejection device is equipped with a pressure detection device at one end of the molding surface of the core.

4. An injection molding method, based on the injection molding equipment according to any one of claims 1-3, characterized in that, include: S1. During the cooling stage of injection molding, obtain the real-time temperature of each molding area on the molding surface of the core of the moving mold; based on the real-time temperature, geometric characteristics and material properties of each molding area, estimate the clamping force of each molding area; identify areas with high clamping force according to the real-time temperature, clamping force and geometric characteristics of each molding area. S2. At the end of the cooling stage and before mold opening, a temperature pulse sequence is applied to the high clamping force area. The temperature pulse sequence includes multiple pulses arranged in chronological order. Each pulse includes a heating stage and a cooling stage. During the heating stage, the controllable heat-conducting component is in a heat-conducting blocking state, and the high clamping force area is heated by the heating device. During the cooling stage, the controllable heat-conducting component is in a heat-conducting connected state, and the heating device is turned off, allowing the residual heat of the high clamping force area to be conducted to the cooling system through the controllable heat-conducting component. S3. After the temperature pulse sequence is applied, the mold is opened, and then the finished product is ejected by the ejection device to separate the finished product from the moving mold and complete the demolding.

5. The injection molding method according to claim 4, characterized in that, The method of estimating the clamping force of each molding zone based on the real-time temperature, geometric characteristics, and material properties of the injection molding material of each molding zone includes: The appropriate geometric coefficients are selected based on the complexity of the geometric features of each forming region; Obtain the effective contact area between each molding area and the finished product; The material properties of the injection molding material are obtained, including the coefficient of thermal expansion, solidification temperature, and elastic modulus. The shrinkage stress of each molding region is obtained based on the real-time temperature of each molding region, the coefficient of thermal expansion, the solidification temperature, and the elastic modulus. The clamping force of each molding area is obtained based on the geometric coefficient, the effective contact area, and the shrinkage stress of each molding area.

6. The injection molding method according to claim 4, characterized in that, The method of estimating the clamping force of each molding zone based on the real-time temperature, geometric characteristics, and material properties of the injection molding material of each molding zone includes: Based on the real-time temperature, geometric features, and material properties of the injection molding material of each molding zone, the initial estimated clamping force of each molding zone is obtained. Obtain the local contact pressure between each molding area and the finished product; The clamping force of each molding area is obtained based on the initial estimated clamping force of each molding area and the local contact pressure between each molding area and the finished product.

7. The injection molding method according to claim 4, characterized in that, The step of identifying high-clamping-force areas based on the real-time temperature, clamping force, and geometric characteristics of each molding area includes: The forming area is a high-clamping-force area if it meets one of the following conditions: The clamping force in the forming area is greater than the preset clamping force threshold. The ratio of the clamping force of the forming area to the average clamping force of all forming areas is greater than a preset ratio; The temperature difference between the real-time temperature of the molding area and the solidification temperature of the injection molding material is greater than the preset temperature difference. The geometric features of the formed area are complex.

8. The injection molding method according to claim 4, characterized in that, After the temperature pulse sequence is applied, the mold is opened, and then the finished product is ejected by the ejection device to separate the finished product from the moving mold, thus completing the demolding process. This includes: The ejection device in the high clamping force area ejects the first stroke at a low speed; The ejection device in all forming areas is driven to eject synchronously at high speed during the second stroke. The ejection device that drives all forming areas synchronously ejects the third stroke at medium speed.

9. The injection molding method according to claim 4, characterized in that, Also includes: Collect demolding process parameters for each injection molding cycle, including the peak demolding force of each ejection device and the surface quality grade of the finished product after demolding; The initial temperature, pulse parameters, and corresponding demolding process parameters of each molding zone in each injection molding cycle are applied as a production record and stored in the historical database. When the number of accumulated production records reaches the preset pulse optimization model update threshold, the pulse optimization model is updated with the initial temperature and pulse parameters applied in each molding zone as input features and the comprehensive optimization target constructed with the peak demolding force and the surface quality level of the finished product after demolding as output. The pulse parameters for the next injection molding cycle are then output by the updated pulse optimization model. The pulse optimization model outputs corresponding pulse parameters based on the initial temperature applied by the temperature pulse sequence of each forming region.

10. The injection molding method according to claim 9, characterized in that, When the number of accumulated production records reaches a preset pulse optimization model update threshold, the pulse optimization model is updated using the initial temperature of the applied temperature pulse sequence in each molding area and the pulse parameters used as input features, and a comprehensive optimization objective constructed from the peak demolding force and the surface quality level of the finished product after demolding as output. This update includes: When the number of accumulated production records reaches the preset pulse optimization model update threshold, a training dataset is constructed using the latest production records of the preset threshold number; a comprehensive cost function is calculated for each production record in the training dataset, which serves as the label value for that production record. The comprehensive cost function is constructed based on the peak demolding force and the surface quality level of the finished product after demolding. The pulse optimization model is trained by using the initial temperature and pulse parameters applied to the temperature pulse sequence of each forming area in each production record as input features and the label value of the production record as output. After training, the updated pulse optimization model is obtained. Specifically, when training the impulse optimization model, time decay weights are assigned to the production records in the training dataset, so that the weight of recent production records is greater than that of distant production records.

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