A casting mold for a vehicle fender assembly and a casting method thereof

Abstract

This invention relates to the field of casting mold technology, specifically a casting mold and casting method for automotive baffle assemblies. The process includes: S1, mold preheating: adjusting the injection mold temperature to 40-80℃ and maintaining this temperature for 15-30 minutes; S2, mold closing and vacuuming: after mold closing, activating the vacuum pumping assembly to reduce the vacuum level in the cavity to below 30 mbar; S3, injection filling: injecting molten plastic at a low speed of 20-50 mm / s to the gate, and then switching to a high speed of 80-150 mm / s for rapid filling after the molten plastic seals the gate. The design employs a segmented temperature control system to specifically control the temperature difference between the thin-walled and thick-walled areas of the mold. Combined with a flow rate compensation mechanism for independently controlled cooling water channels, this innovative design solves the problems of insufficient filling and shrinkage deformation in unevenly thick plastic parts from the source. This allows the deformation of the plastic part to be controlled within 0.03 mm, reducing the defect rate by more than 70% compared to traditional processes.

Description

Technical Field

[0001] This invention relates to the field of casting mold technology, specifically a casting mold for automobile baffle assemblies and its casting method. Background Technology

[0002] As a core decorative and protective component of the vehicle body, the molding quality of the automotive baffle assembly directly affects the overall appearance harmony and operational safety of the vehicle. With the automotive industry moving towards lightweighting, high precision, and high integration, plastic materials such as PP, PP-modified glass fiber, and other plastic materials are gradually replacing traditional metal materials as the mainstream choice for automotive baffles due to their advantages such as light weight, good moldability, and low cost. However, plastic materials themselves have characteristics such as poor flowability, high cooling shrinkage rate, and susceptibility to internal stress. Furthermore, the automotive baffle assembly has a complex structure, typically containing both thin-walled areas (2.5~3.5mm thick) and thick-walled reinforcing rib areas (3.5~6mm thick).

[0003] Currently, the casting of automotive plastic baffles in the industry mainly adopts conventional injection molding process. Its core process is mold preheating → mold closing → injection filling → pressure holding → cooling and shaping → mold opening and part removal. The supporting molds mostly adopt linear cooling water channels and simple venting groove structures, and the process parameters and mold structure lack targeted design.

[0004] In actual production, this traditional process and mold have significant defects: First, the injection filling stage often uses a single injection speed, which easily leads to surface scratches and flow marks caused by molten material impacting the cavity wall, or problems such as material shortage in thin-walled areas and shrinkage cavities and porosity in thick-walled areas due to excessively slow filling speed. Moreover, the air remaining in the cavity after mold closing cannot be effectively discharged, resulting in air bubbles and air marks inside the plastic part, which seriously affects the density and mechanical properties of the plastic part. Second, the cooling process often uses a linear cooling water channel with a uniform temperature and flow rate, which cannot be adapted to the uneven thickness of the baffle assembly. This easily leads to slow cooling in thick-walled areas and excessively fast cooling in thin-walled areas, resulting in a large difference in cooling rate between the inside and outside of the plastic part, which in turn causes warping deformation and dimensional deviations. Furthermore, the high-temperature areas of the mold cannot be cooled in time, which can easily lead to mold deformation and accelerated wear after long-term use, shortening the mold's service life. Third, the mold venting structure relies solely on natural venting at the parting surface, resulting in low venting efficiency, which cannot meet the venting requirements of high-precision plastic parts. Moreover, molten material easily clogs the venting grooves, requiring frequent shutdowns for cleaning, which reduces production efficiency. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a casting mold for automotive baffle assemblies and a casting method thereof, in order to solve problems such as scratches during the injection filling stage and material shortage in thin-walled areas and shrinkage cavities and porosity in thick-walled areas caused by excessively slow filling speed.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a casting method for automobile baffle assembly, S1, mold preheating: adjust the temperature of the injection mold to 40~80℃ and keep it at that temperature for 15~30 minutes; S2. Mold closing and vacuuming: After the mold is closed, start the vacuum pumping component to pump the vacuum level in the cavity to below 30mbar. S3, Injection molding: Inject the molten plastic into the gate at a low speed of 20-50 mm / s. After the molten plastic seals the gate, switch to high speed of 80-150 mm / s for rapid molding. S4. Pressure Holding and Shrink Compensation: After filling, pressure holding is performed. The pressure holding pressure is 40~80MPa and the pressure holding time is 5~12 seconds. S5. Cooling and Shaping: The mold is cooled by conformal cooling water channels and high-pressure point cooling components, and the mold temperature is controlled within the range of 40~90℃, with a cooling time of 10~30 seconds; S6. Mold opening and part removal: After cooling, the mold is opened and the plastic part is ejected through the ejection mechanism; S7. Post-processing: Stress relief and trimming of the plastic parts.

[0007] Preferably, the temperature adjustment in step S1 is to perform segmented temperature adjustment on the mold so that the mold temperature in the thin-walled area of ​​the corresponding plastic baffle is 5°C to 15°C higher than the temperature in the thick-walled area. Temperature balance fluctuations are compensated by controlling the flow rate of the independently controlled cooling water circuits in each zone.

[0008] Preferably, the vacuum pumping component in S2 includes a vacuum exhaust component. When the integrated vacuum exhaust component is activated, an injection permission signal is fed back to the control system when the absolute pressure inside the cavity is lower than 30 mbar. Precision injection molding controls the molten plastic to enter the cavity at a stepped, progressively increasing rate through a multi-stage buffered pouring process, based on changes in cavity filling volume and pressure.

[0009] Preferably, during the cooling and setting process in step S5, a mold temperature controller is used to control the overall temperature of the mold. The mold temperature controller is set to 60±10℃, and the cooling water flow rate is 5~15L / min; and, The high-pressure cooling unit starts pre-cooling 0.5 to 1.0 seconds before the injection begins, continues cooling during the injection process, and stops cooling 2 to 3 seconds after the pressure holding period ends.

[0010] Preferably, after step S7, a surface treatment step is further included to polish the plastic part for 10 to 30 seconds to improve the adhesion of the plastic part surface.

[0011] A casting mold for an automotive baffle assembly, comprising a fixed mold assembly and a moving mold assembly; The fixed mold assembly includes a fixed mold frame and a fixed mold core, and the moving mold assembly includes a moving mold frame and a moving mold core; After the fixed mold core and the moving mold core are closed, a cavity is formed for molding the plastic automotive baffle assembly; and, The exhaust system includes exhaust channels for placement on the fixed mold core and the moving mold core, an air collection channel communicating with the exhaust channels, and a vacuum pumping assembly connected to the air collection channel; and, The cooling system includes conformal cooling water channels, high-pressure spot cooling components, and local heat-conducting inserts. The conformal cooling water channels are designed to conform to the wall thickness distribution of the plastic automotive baffle assembly, and the high-pressure spot cooling components are located in the local high-temperature areas of the mold.

[0012] Preferably, the conformal cooling water channel is a drilled conformal water channel with a water channel diameter of 6-12 mm, a distance of 8-15 mm between the water channel and the cavity surface, and a spacing of 15-30 mm between adjacent water channels.

[0013] Preferably, the local heat-conducting insert is set in the thick-walled area and high-temperature concentrated area of ​​the mold, and the heat-conducting insert is connected to the mold base by interference fit with an interference amount of 0.01 to 0.03 mm.

[0014] Preferably, the depth of the exhaust groove is 0.02 to 0.05 mm, and an exhaust block is provided at the end of the exhaust groove. The exhaust block is made of porous and breathable steel with a porosity of 40% to 60%.

[0015] Preferably, the vacuum pumping assembly includes a vacuum pump, a vacuum tank, and a vacuum pipeline. A shut-off valve is installed between the vacuum pipeline and the gas collection tank. The shut-off valve is automatically closed by the impact force of the flowing molten plastic.

[0016] Preferably, the inner surface of the cavity is deposited with a gradient functional material coating, which consists of an adhesive layer, a heat insulation layer and an anti-stick and wear-resistant layer from the substrate to the surface, with a total thickness of 50μm to 150μm.

[0017] Preferably, the non-stick and wear-resistant layer has a coating thickness of 20~30μm, and the coating components include polytetrafluoroethylene, ceramic micro powder and organosilicon resin.

[0018] The beneficial effects of this invention are: (1) The casting mold and casting method for automotive baffle assemblies described in this invention adopts a segmented temperature control design to specifically control the temperature difference between the thin-walled and thick-walled areas of the mold. Combined with a flow rate compensation mechanism for independently controlled cooling water channels, this design solves the problem of insufficient filling and shrinkage deformation of uneven plastic parts from the source. This innovative design controls the deformation of the plastic parts to within 0.03 mm, and the defect rate is reduced by more than 70% compared with traditional processes. At the same time, a graded buffer injection mode of low-speed sealing and step-by-step high-speed filling is adopted, combined with the pressure feedback control of the integrated vacuum exhaust component, to ensure that the vacuum degree of the cavity is stable below 30 mbar before injection, eliminating defects such as bubbles and gas lines caused by gas residue, and increasing the filling qualification rate to 99.5%.

[0019] (2) The casting mold and casting method for automotive baffle assembly described in this invention, with a porous venting steel exhaust block and an automatic shut-off valve structure, realizes the dual functions of exhaust and preventing molten material blockage, eliminating the need for frequent machine shutdowns for cleaning and reducing the mold maintenance frequency by 70%; the gradient functional material coating on the cavity surface, which integrates polytetrafluoroethylene and ceramic micro powder components, not only improves the wear resistance of the mold and increases the service life of the mold from 300,000 mold cycles to more than 500,000 mold cycles, but also solves the problem of plastic parts sticking and improves the part removal efficiency. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a three-dimensional structural diagram of the fixed mold assembly and the moving module of the present invention; Figure 3 This is a schematic diagram of the three-dimensional structure of the water pipe arrangement within the fixed mold assembly of the present invention; Figure 4 This is a schematic diagram of the three-dimensional structure of the moving mold core of the present invention; Figure 5 This is a schematic diagram of the three-dimensional structure of the fixed mold core of the present invention; Figure 6 For the present invention Figure 5 A sectional view; Figure 7 For the present invention Figure 6 Enlarged view of point A in the middle; Figure 8 This is a flowchart of a casting method for an automotive baffle assembly according to the present invention.

[0022] In the diagram: 100-fixed mold frame; 110-fixed mold core; 111-heat-conducting insert; 112-water channel; 113-material coating; 120-water pipe; 121-water pipe connector; 130-venting system; 131-gas connector; 200-moving mold frame; 210-moving mold core; 300-injection head; 310-gate; 500-guide rod. Detailed Implementation

[0023] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0024] like Figures 1 to 8 As shown, a casting method for an automotive baffle assembly according to the present invention includes the following steps: S1, mold preheating: adjusting the temperature of the injection mold to 40~80℃ and holding it at that temperature for 15~30 minutes. S2. Mold closing and vacuuming: After the mold is closed, start the vacuum pumping component to pump the vacuum level in the cavity to below 30mbar. S3, Injection filling: Inject the molten plastic into the gate 310 at a low speed of 20-50 mm / s. After the molten plastic seals the gate 310, switch to high speed of 80-150 mm / s for rapid filling. S4. Pressure Holding and Shrink Compensation: After filling, pressure holding is performed. The pressure holding pressure is 40~80MPa and the pressure holding time is 5~12 seconds. S5. Cooling and Shaping: The mold is cooled by conformal cooling water channel 112 and high-pressure point cooling component, and the mold temperature is controlled within the range of 40~90℃, with a cooling time of 10~30 seconds; S6. Mold opening and part removal: After cooling, the mold is opened and the plastic part is ejected through the ejection mechanism; S7. Post-processing: Stress relief and trimming of the plastic parts.

[0025] The materials used in automotive baffle assemblies vary depending on the car model and the company's design philosophy. The molding material in this application is a plastic melt, which can be PP and 20% glass fiber, ABS or PP / ABS alloy, etc. The melting temperature of the plastic melt is 180~240℃, and the plasticization amount of the plastic melt in the barrel is 100%~130% of the cavity volume.

[0026] The complete injection molding process, through closed-loop control of the above steps, solves problems such as residual gas in the mold cavity, uneven filling, shrinkage and deformation of the plastic part, and stress concentration during plastic injection, ensuring that the quality of the molded plastic part meets the precision requirements of automotive parts. First, the mold is preheated and kept at a constant temperature to prevent the molten plastic from cooling rapidly and obstructing filling due to a low-temperature mold. During mold closing, guide rods 500 guide the mold, and after mold closing, vacuum is applied to remove air from the cavity to prevent air bubbles. Injection is carried out through multiple injection heads 300, using a staged injection method of low-speed sealing and high-speed filling, balancing the sealing of the gate 310 and the efficiency of cavity filling, avoiding molten material splashing and insufficient filling. After filling, pressure is maintained to compensate for shrinkage during the cooling process. Targeted cooling ensures rapid and uniform temperature setting of the plastic part. Finally, post-processing eliminates internal stress and refines the appearance to ensure product quality.

[0027] Among these measures, the production process involves graded injection, precise pressure holding, and cooling control based on the characteristics of the molten plastic material. This effectively reduces defects such as shrinkage cavities, porosity, deformation, and burrs in the plastic parts, ensuring that the dimensional tolerances and shape accuracy of the automotive baffles meet assembly requirements. Reasonable preheating and cooling time settings balance molding quality and production cycle time, avoiding damage to parts due to insufficient cooling or reduced efficiency due to excessive cooling.

[0028] For the specific automotive front fender assembly: the material is PP + 20% glass fiber, with a thickness of 2.5-6mm and external dimensions of 1200mm*800mm*50mm; before production, the mold is preheated, with the injection mold temperature adjusted to 60℃ and continuously maintained at this temperature for 20 minutes using a mold temperature controller to ensure uniform temperature throughout the mold. After the fixed mold and moving mold are closed, the vacuum extraction component is activated and continuously extracted for 3 seconds to achieve a vacuum level of 25mbar in the cavity. Once the set value is reached, extraction is stopped and the vacuum state is maintained. The PP and 20% glass fiber melt at 220℃ is injected into the gate 310 at a low speed of 35mm / s. After the melt completely seals the gate 310 for approximately 1.5 seconds, the injection speed is immediately switched to 120℃. With a high speed of mm / s, the total filling time of the cavity is approximately 8 seconds. After filling, a holding pressure of 60MPa is immediately applied and maintained for 8 seconds to compensate for the volume shrinkage during the cooling process of the molten material. The mold temperature is controlled to be stable at 65℃ through the conformal cooling water channel 112 with a cooling water temperature of 50℃ and a flow rate of 10L / min and a high-pressure point cooling component. The cooling is maintained for 20 seconds to ensure that the plastic part is completely shaped and the temperature is uniform. After cooling, the mold is opened and the plastic part is smoothly ejected by the ejection mechanism. There are no scratches or deformations during the removal process. The plastic part is placed in a hot air circulating oven at 80℃ for stress relief treatment for 30 minutes. Then, a special trimming tool is used to remove 300 burrs from the injection head and trim the edges of the plastic part to ensure a smooth appearance.

[0029] In actual mass production, five out of every hundred parts are randomly selected for inspection. The dimensional tolerance of the inspected automotive front fender assemblies is controlled within ±0.1mm, with no defects such as bubbles, shrinkage cavities, or deformation, and the surface is smooth and flat. Testing shows that the plastic parts have a tensile strength ≥20MPa and an impact strength ≥5kJ / m², meeting the usage requirements for automotive fender assemblies. The production cycle time is consistently 70 seconds per piece.

[0030] As a preferred technical solution, the temperature adjustment in step S1 is to perform segmented temperature adjustment on the mold so that the mold temperature in the thin-walled area of ​​the corresponding plastic baffle is 5°C~15°C higher than the temperature in the thick-walled area. Temperature balance fluctuations are compensated by controlling the flow rate of the independently controlled cooling water circuit 112 in each zone.

[0031] The design takes into account the high temperature of the mold in the thin-walled area, which can avoid insufficient filling and surface material shortage caused by rapid cooling of the molten material. Segmented temperature regulation is adopted so that the mold temperature corresponding to the thin-walled area is 5~15℃ higher than that of the thick-walled area. The temperature difference is used to regulate the cooling rate of the molten material. The mold temperature in the thick-walled area is slightly lower, which can accelerate the cooling rate and reduce shrinkage cavities and porosity defects in the thick-walled parts. The flow rate of the independently controlled cooling water channels 112 is adjusted to compensate for temperature fluctuations in the mold in real time. For example, the flow rate of the cooling water channels 112 in the thick-walled area is increased, while the flow rate in the thin-walled area is decreased, ensuring the overall temperature of the mold and further improving the uniformity of the plastic parts molding.

[0032] As a preferred technical solution, the vacuum pumping component in S2 includes a vacuum exhaust component. When the integrated vacuum exhaust component is activated, a signal to allow injection is fed back to the control system when the absolute pressure inside the cavity is lower than 30 mbar. Precision injection molding controls the molten plastic to enter the cavity at a stepped, progressively increasing rate through a multi-stage buffered pouring process, based on changes in cavity filling volume and pressure.

[0033] An integrated vacuum exhaust assembly is used to combine exhaust and vacuuming functions. It monitors the absolute pressure inside the cavity in real time. When the pressure is below 30 mbar, it sends an injection permission signal to the control system to prevent injection from starting before the set vacuum level is reached, ensuring that there is no air residue in the cavity. Employing precision injection molding control, sensors detect changes in cavity filling volume and pressure in real time, controlling the molten plastic to enter the cavity at a stepped increasing speed through a multi-stage buffer gating system. The stepped increasing speed avoids scratches and bubbles on the surface of the plastic part caused by the molten material impacting the cavity wall, while the multi-stage buffer gating ensures that the molten material fills the cavity smoothly, reducing uneven filling problems caused by sudden changes in flow rate.

[0034] The integrated vacuum exhaust assembly includes a vacuum pump, a pressure sensor, and an exhaust channel. The pressure sensor detects the absolute pressure inside the cavity in real time. When the pressure drops to 25 mbar, it sends an injection permission signal to the control system. The control system starts the injection after a 0.5-second delay to ensure a stable vacuum. During the product testing process, the plastic parts were free of bubbles and air marks inside, and free of flow marks and weld marks on the surface. The weld strength was ≥20MPa, and the filling qualification rate reached 99.5%. Compared with the traditional injection method, the surface defect rate was reduced by 70%, and the filling stability was significantly improved.

[0035] As a preferred technical solution, during the cooling and shaping process in step S5, a mold temperature controller is used to control the overall temperature of the mold. The mold temperature controller is set to a temperature of 60±10℃, and the cooling water flow rate is 5~15L / min; and... The high-pressure cooling unit starts pre-cooling 0.5 to 1.0 seconds before the injection begins, continues cooling during the injection process, and stops cooling 2 to 3 seconds after the pressure holding period ends.

[0036] A mold temperature controller is used to control the overall mold temperature, set at 60±10℃. A stable cooling water flow rate of 5~15L / min ensures that the overall mold temperature is within a reasonable range, avoiding excessively high or low local temperatures. The working sequence of the high-pressure cooling components is precisely controlled. Pre-cooling is initiated 0.5~1.0 seconds before injection to reduce the temperature of local high-temperature areas of the mold, such as thick-walled areas and around the injection head (around 300mm), preventing overheating and degradation of the molten material upon contact with the high-temperature mold. Continuous cooling is maintained during injection to ensure uniform cooling of the molten material. Cooling is stopped 2~3 seconds after the holding pressure is completed to compensate for temperature fluctuations during the holding pressure stage, further ensuring sufficient shaping of the plastic part and reducing shrinkage deformation.

[0037] The precise temperature control of the mold temperature controller and the regulation of cooling water flow prevent excessive temperature fluctuations in the mold, ensuring uniform cooling of the plastic parts and reducing deformation. The timing control of the high-pressure spot cooling components precisely cools localized high-temperature areas of the mold, preventing molten material degradation and scorching of the plastic part surface, while also accelerating localized cooling and improving production cycle time. Pre-cooling is initiated 1 second before injection, introducing high-pressure cooling water into the thick-walled area of ​​the mold and the spot cooling channel near the injection head (300mm). Cooling continues during injection, and after the holding pressure is completed, cooling stops after a 2.5-second delay to ensure the temperature of the thick-walled area drops below 60℃ before stopping. Subsequent product testing shows that the overall mold temperature fluctuation is controlled within ±5℃, with no overheating in localized high-temperature areas. The thick-walled areas of the plastic parts are cooled uniformly, without shrinkage cavities or deformation. The dimensional stability of the plastic parts after shaping is improved; after 24 hours of storage, the deformation of the plastic parts is ≤0.03mm, far exceeding industry standards.

[0038] As a preferred technical solution, a surface treatment step is also included after step S7, in which the plastic part is polished for 10 to 30 seconds to improve the adhesion of the plastic part surface.

[0039] Grinding is a fine-tuning process for plastic parts. It removes minor burrs, flow marks, scratches, and other imperfections, while increasing surface roughness and improving adhesion. This lays the foundation for subsequent processes such as painting and bonding, including on automotive dashboards, preventing coatings and adhesives from peeling off and ensuring the dashboard's appearance and lifespan. Grinding time should be controlled between 10 and 30 seconds to achieve the desired finishing effect while avoiding over-grinding that could lead to uneven wall thickness and surface damage.

[0040] A casting mold for an automotive baffle assembly, comprising a fixed mold assembly and a moving mold assembly; The fixed mold assembly includes a fixed mold frame 100 and a fixed mold core 110, and the moving mold assembly includes a moving mold frame 200 and a moving mold core 210; After the fixed mold core 110 and the moving mold core 210 are closed, a cavity is formed for molding the plastic automotive baffle assembly; and, The exhaust system 130 includes an exhaust groove for being disposed on the fixed mold core 110 and the moving mold core 210, an air collection groove communicating with the exhaust groove, and a vacuum pumping assembly connected to the air collection groove; and, The cooling system includes a conformal cooling water channel 112, a high-pressure spot cooling component, and a local heat-conducting insert 111. The conformal cooling water channel 112 is designed to conform to the wall thickness distribution of the plastic automotive baffle assembly. The high-pressure spot cooling component is located in the local high-temperature area of ​​the mold.

[0041] After the fixed mold frame 100 and fixed mold core 110 of the fixed mold assembly are closed with the moving mold frame 200 and moving mold core 210 of the moving mold assembly, a cavity with the same shape as the automobile baffle assembly is formed for molding plastic molten material; the exhaust system 130 includes an exhaust groove and an air collection groove connected to a vacuum pumping assembly to exhaust air and gases volatilized from the molten material in the cavity. The vacuum tube of the exhaust system 130 is arranged in the receiving hole 116, which, together with the vacuuming step in the casting method, ensures that there is no gas residue in the cavity; the cooling system includes a conformal cooling water channel 112, a high-pressure spot cooling assembly, and a local heat-conducting insert. Part 111 achieves precise cooling based on the wall thickness and temperature distribution characteristics of the automotive baffle. The conformal cooling water channel 112 fits the cavity surface to ensure uniform overall cooling. The cooling water channel 112 is connected to the water pipe 120 through the water pipe connector 121. The water flow rate and pressure in the water channel 112 are controlled by multiple sets of water pipes 120. The high-pressure spot cooling component enhances cooling for local high-temperature areas. The local heat-conducting insert 111 accelerates heat conduction in thick-walled areas. Combined with the cooling and shaping steps in the casting method, the plastic part is quickly and uniformly shaped, ensuring molding quality.

[0042] As a preferred technical solution, the conformal cooling water channel 112 is a drilled conformal water channel 112 with a diameter of 6 to 12 mm, a distance of 8 to 15 mm between the water channel 112 and the surface of the cavity, and a spacing of 15 to 30 mm between adjacent water channels 112.

[0043] The mold features drilled conformal cooling channels 112 with a diameter of 6–12 mm, ensuring sufficient cooling water flow and improving heat transfer efficiency. The conformal cooling channels 112 are 8–15 mm away from the cavity surface, ensuring effective cooling while preventing insufficient cooling due to excessive distance, and also preventing the mold cavity walls from becoming too thin and lacking strength due to excessively close proximity. The spacing between adjacent cooling channels 112 is 15–30 mm, ensuring uniform cooling across all areas of the cavity surface, avoiding cooling dead zones, further improving the cooling uniformity of the plastic part, and reducing deformation.

[0044] Among them, the sufficient diameter of the conformal water channel 112 ensures the cooling water flow, quickly removes the heat from the mold, shortens the cooling time, and increases the production cycle. The reasonable distance between the water channel 112 and the cavity avoids insufficient strength of the mold cavity wall.

[0045] As a preferred technical solution, the local heat-conducting insert 111 is disposed in the thick-walled area and high-temperature concentrated area of ​​the mold, and the heat-conducting insert 111 is connected to the mold base by an interference fit with an interference amount of 0.01 to 0.03 mm.

[0046] The local heat-conducting insert 111 is placed in the thick-walled area and high-temperature concentrated area of ​​the mold, such as near the injection head 300 and the reinforcing rib. The local heat-conducting insert 111 of the mold in this application is installed near the injection head 300. The oxygen-free copper material used has a thermal conductivity of 401W / (m·K) and its shape is perfectly matched with the thick-walled area of ​​the mold.

[0047] The high thermal conductivity of the heat-conducting insert 111 is utilized to quickly conduct heat in the thick-walled area, accelerating the cooling rate of this area and compensating for the insufficient cooling of the conformal cooling water channel 112 in the thick-walled area. The heat-conducting insert 111 and the mold base adopt an interference fit with an interference of 0.01 to 0.03 mm to ensure that the insert and the base are tightly fitted without gaps, avoiding obstruction of heat conduction. At the same time, it ensures that the insert is firmly installed and does not loosen or fall off during repeated opening and closing, cooling and heating of the mold.

[0048] In actual production, the cooling time of the thick-walled area is shortened to 15 seconds. Compared with the solution without the heat-conducting insert 111, the temperature drop rate of the thick-walled area is increased by 40%, there are no shrinkage cavities or porosity defects, the cooling rate of the thick-walled area and the thin-walled area of ​​the plastic part tends to be consistent, and the overall deformation is ≤0.03mm.

[0049] As a preferred technical solution, the depth of the exhaust groove is 0.02 to 0.05 mm, and an exhaust block is provided at the end of the exhaust groove. The exhaust block is made of porous and breathable steel with a porosity of 40% to 60%.

[0050] The depth of the venting groove is 0.02 to 0.05 mm. This depth ensures that the gas in the mold cavity can be smoothly discharged and enter the gas collection groove through the venting groove. It also prevents the plastic melt from overflowing. The melt viscosity is too high to pass through the venting groove at this depth. A porous venting block made of breathable steel is set at the end of the venting groove. The porosity of the breathable steel is 40% to 60%. It can further filter the small melt particles in the gas, prevent the melt from clogging the venting groove, and improve the venting efficiency. It ensures that the gas in the mold cavity is completely discharged. In conjunction with the vacuum pumping component, it can further improve the vacuum in the mold cavity.

[0051] Reasonable venting groove depth and porous venting steel venting blocks ensure that the gas in the mold cavity is discharged quickly and completely, avoiding defects such as bubbles and air marks.

[0052] As a preferred technical solution, the vacuum pumping assembly includes a vacuum pump, a vacuum tank, and a vacuum pipeline. A shut-off valve is provided between the vacuum pipeline and the gas collection tank. The shut-off valve is automatically closed by the impact force of the flowing molten plastic material.

[0053] The vacuum pumping assembly consists of a vacuum pump, a vacuum tank, and a vacuum pipeline. The vacuum pump provides the pumping power, the vacuum tank is used to stabilize the vacuum level and avoid vacuum fluctuations during the pumping process, the vacuum pipeline connects the gas collection tank to the vacuum tank, and the pipeline of the vacuum tank is connected to the gas connector 131. A shut-off valve is installed between the vacuum pipeline and the gas collection tank. This shut-off valve is passively controlled and automatically closes due to the impact force of the flowing molten plastic.

[0054] When the molten plastic fills to the inlet of the gas collecting tank, the flow impact force of the molten material pushes the shut-off valve to close, preventing the molten material from entering the vacuum pipeline, avoiding blockage of the vacuum pipeline and damage to the vacuum pump. At the same time, it ensures that the vacuuming process is completed before the molten material is filled, so as not to affect the filling process.

[0055] The automatic shut-off function of the shut-off valve can effectively prevent molten material from entering the vacuum pipeline and vacuum pump, avoiding equipment damage and reducing equipment maintenance costs.

[0056] As a preferred technical solution, the inner surface of the cavity is deposited with a gradient functional material coating 113, which consists of an adhesive layer, a heat insulation layer and an anti-stick and wear-resistant layer from the substrate to the surface, with a total thickness of 50μm~150μm.

[0057] A gradient functional material coating 113 is deposited on the inner surface of the cavity. The coating consists of an adhesive layer, a heat insulation layer, and an anti-stick and wear-resistant layer from the mold substrate to the surface, with a total thickness controlled between 50 μm and 150 μm. The adhesive layer is used to enhance the adhesion between the coating and the mold substrate and to prevent the coating from peeling off; The heat insulation layer can reduce heat loss from the surface of the mold cavity and maintain a stable cavity temperature. Combined with the conformal cooling water channel 112, it optimizes the temperature control effect. The non-stick and wear-resistant layer can reduce the friction between the molten plastic and the cavity surface, preventing the plastic part from sticking to the cavity surface. At the same time, it can improve the wear resistance of the cavity surface, reduce mold wear, and extend the service life of the mold.

[0058] The total coating thickness is 100μm, and the thickness and material of each layer are as follows: the adhesive layer is 20μm thick, made of NiCr alloy, and is coated by plasma spraying to enhance the bonding force with the mold substrate Cr12MoV. The insulation layer is 50μm thick and made of ZrO2 ceramic, which has good thermal insulation performance and can reduce heat loss. The anti-stick and wear-resistant layer is 30μm thick and is composed of polytetrafluoroethylene, ceramic micro powder and silicone resin, and is formed by spraying process.

[0059] After coating deposition, the cavity surface is polished to ensure surface roughness Ra≤0.2μm.

[0060] During the production process, after 500,000 production cycles, the coating and mold substrate are firmly bonded, the temperature fluctuation of the cavity surface is ≤2℃, and the heat insulation effect is significant; the plastic parts are picked up smoothly without sticking, the picking time is shortened to 1.5 seconds, the mold cavity surface has no obvious wear, and the service life is extended to more than 500,000 cycles, which is 60% higher than that of uncoated molds.

[0061] As a preferred technical solution, the anti-stick and wear-resistant layer has a coating thickness of 20~30μm, and the coating components include polytetrafluoroethylene, ceramic micro powder and organosilicon resin.

[0062] The thickness of the anti-stick and wear-resistant layer is 20~30μm. This thickness ensures both anti-stick and wear-resistant effects while avoiding excessive coating thickness that could lead to dimensional deviations in the mold cavity. The coating consists of polytetrafluoroethylene (PTFE), ceramic micropowder, and silicone resin. PTFE has excellent anti-stick properties, reducing friction between the molten material and the mold cavity and preventing the plastic parts from sticking together. Ceramic micropowder enhances the wear resistance and hardness of the coating, reducing mold wear. Silicone resin strengthens the flexibility and adhesion of the coating, preventing cracking and peeling. The three components work synergistically to further improve the overall performance of the anti-stick and wear-resistant layer.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A casting method for an automotive baffle assembly, characterized in that: S1. Mold preheating: Adjust the temperature of the injection mold to 40~80℃ and keep it warm for 15~30 minutes; S2. Mold closing and vacuuming: After the mold is closed, start the vacuum pumping component to pump the vacuum level in the cavity to below 30mbar. S3, Injection molding: Inject the molten plastic into the gate at a low speed of 20-50 mm / s. After the molten plastic seals the gate, switch to high speed of 80-150 mm / s for rapid molding. S4. Pressure Holding and Shrink Compensation: After filling, pressure holding is performed. The pressure holding pressure is 40~80MPa and the pressure holding time is 5~12 seconds. S5. Cooling and Shaping: The mold is cooled by conformal cooling water channels and high-pressure point cooling components, and the mold temperature is controlled within the range of 40~90℃, with a cooling time of 10~30 seconds; S6. Mold opening and part removal: After cooling, the mold is opened and the plastic part is ejected through the ejection mechanism; S7. Post-processing: Stress relief and trimming of the plastic parts.

2. The casting method for an automotive baffle assembly according to claim 1, characterized in that: The temperature adjustment in step S1 involves segmenting the mold temperature to ensure that the mold temperature in the thin-walled area of ​​the corresponding plastic baffle is 5°C to 15°C higher than that in the thick-walled area. and / or; Temperature balance fluctuations are compensated by controlling the flow rate of the independently controlled cooling water circuits in each zone.

3. The casting method for an automotive baffle assembly according to claim 1, characterized in that: The vacuum pumping component in S2 includes a vacuum exhaust component. When the integrated vacuum exhaust component is activated, a signal to allow injection is sent to the control system when the absolute pressure inside the cavity is lower than 30 mbar. Precision injection molding controls the molten plastic to enter the cavity at a stepped, progressively increasing rate through a multi-stage buffered pouring process, based on changes in cavity filling volume and pressure.

4. A casting method for an automotive baffle assembly according to claim 2, characterized in that: During step S5, the cooling and shaping process, a mold temperature controller is used to control the overall temperature of the mold. The mold temperature controller is set to 60±10℃, and the cooling water flow rate is 5~15L / min; and, The high-pressure cooling unit starts pre-cooling 0.5 to 1.0 seconds before the injection begins, continues cooling during the injection process, and stops cooling 2 to 3 seconds after the pressure holding period ends.

5. A casting method for an automotive baffle assembly according to claim 1, characterized in that: After step S7, a surface treatment step is also included, in which the plastic part is polished for 10 to 30 seconds to improve the adhesion of the plastic part surface.

6. A casting mold for an automotive baffle assembly, the device being suitable for the above-described method, characterized in that: Includes fixed mold components and moving modules; The fixed mold assembly includes a fixed mold frame and a fixed mold core, and the moving mold assembly includes a moving mold frame and a moving mold core; After the fixed mold core and the moving mold core are closed, a cavity is formed for molding the plastic automotive baffle assembly; and, The exhaust system includes exhaust channels for placement on the fixed mold core and the moving mold core, an air collection channel communicating with the exhaust channels, and a vacuum pumping assembly connected to the air collection channel; and, The cooling system includes conformal cooling water channels, high-pressure spot cooling components, and local heat-conducting inserts. The conformal cooling water channels are designed to conform to the wall thickness distribution of the plastic automotive baffle assembly, and the high-pressure spot cooling components are located in the local high-temperature areas of the mold.

7. A casting mold for an automotive baffle assembly according to claim 6, characterized in that: The conformal cooling water channel is a drilled conformal water channel with a water channel diameter of 6-12mm, a distance of 8-15mm between the water channel and the cavity surface, and a spacing of 15-30mm between adjacent water channels.

8. A casting mold for an automotive baffle assembly according to claim 7, characterized in that: The local heat-conducting insert is installed in the thick-walled area and high-temperature concentrated area of ​​the mold. The heat-conducting insert is connected to the mold base with an interference fit, and the interference amount is 0.01 to 0.03 mm.

9. A casting mold for an automotive baffle assembly according to claim 6, characterized in that: The depth of the exhaust groove is 0.02 to 0.05 mm, and an exhaust block is provided at the end of the exhaust groove. The exhaust block is made of porous and breathable steel with a porosity of 40% to 60%.

10. A casting mold for an automotive baffle assembly according to claim 9, characterized in that: The vacuum pumping assembly includes a vacuum pump, a vacuum tank, and a vacuum pipeline. A shut-off valve is installed between the vacuum pipeline and the gas collection tank. The shut-off valve is automatically closed by the impact force of the flowing molten plastic material.

11. A casting mold for an automotive baffle assembly according to claim 7, characterized in that: The inner surface of the cavity is coated with a gradient functional material, consisting of an adhesive layer, a heat insulation layer, and an anti-stick and wear-resistant layer, with a total thickness of 50μm to 150μm, from the substrate to the surface.

12. A casting mold for an automotive baffle assembly according to claim 11, characterized in that: The anti-stick and wear-resistant layer has a coating thickness of 20~30μm, and the coating components include polytetrafluoroethylene, ceramic micro powder and organosilicon resin.

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