A control method for injection molding of a plastic spoiler of an automobile without trimming gate and a mold thereof

Abstract

The present application relates to a kind of automobile plastic spoiler free shearing gate injection molding control method and its mould, it is related to automobile parts processing technical field, it includes: in response to injection signal, obtain product information and mould structure;From mould structure, read runner parameter, cavity structure, gate position and gate size;According to cavity structure, determine the corresponding feeding component of gate position and flow distance;Based on feeding component, match corresponding demand flow rate;Combining gate size, demand flow rate and product information, determine gate demand pressure;According to runner parameter, gate demand pressure and flow distance, determine injection demand pressure;Combining product information, injection demand pressure, flow distance and demand flow rate, determine the valve needle opening degree corresponding to gate position;Integrate gate position and valve needle opening degree to determine and execute valve needle control instruction.The present application has the effect of reducing residual gate condensate after injection molding is completed.

Description

Technical Field

[0001] This invention relates to the field of automotive parts processing technology, and in particular to a method for controlling injection molding of automotive plastic spoilers without shearing the gate and its mold. Background Technology

[0002] A spoiler is an automotive component used to optimize airflow around the vehicle. Its core function is to generate downward aerodynamic pressure at high speeds through an inverted airfoil cross-section and a specific installation angle, which counteracts lift at the rear of the vehicle and simultaneously streamlines the tail vortex, reducing aerodynamic drag.

[0003] Currently, spoilers are generally produced using plastic injection molding. To further reduce processing and assembly costs, the industry typically adopts an integrated injection molding design, which involves pre-setting the functional component installation structure during the mold development stage, so that the above-mentioned functional structure and the main body of the spoiler slope are integrally injection molded, eliminating the subsequent manual assembly process and improving production efficiency.

[0004] However, the addition of the functional structure prevents the main body of the spoiler slope from being directly opposite the conventional injection port. Due to the spatial interference of the functional structure, the conventional injection port must be located far away from the main body of the spoiler slope, resulting in a long amount of solidified material remaining after injection molding, which increases the cost of manual cleaning and waste recycling. Summary of the Invention

[0005] To reduce residual sprue material after injection molding, this invention provides a method for controlling injection molding of automotive plastic spoilers without shearing the sprue and a mold thereof.

[0006] In a first aspect, this application provides a method for controlling the injection molding of automotive plastic spoilers without shearing the gate, employing the following technical solution:

[0007] A method for controlling the injection molding of automotive plastic spoilers without gate shearing includes:

[0008] S10: Responds to the injection signal and obtains product information and mold structure;

[0009] S11: Read the runner parameters, cavity structure, gate location, and gate size from the mold structure;

[0010] S12: Determine the injection quantity and flow distance corresponding to the gate location based on the cavity structure;

[0011] S13: Match the required flow rate based on the glue injection component;

[0012] S14: Determine the gate pressure requirement by combining the gate size, required flow rate, and product information;

[0013] S15: Determine the injection pressure requirement based on the runner parameters, gate pressure requirement, and flow distance;

[0014] S16: Determine the valve needle opening corresponding to the gate location by combining product information, injection molding pressure requirements, flow distance, and required flow rate;

[0015] S17: Integrate the gate position and valve needle opening determination and execute the valve needle control command.

[0016] By adopting the above technical solution, based on the cavity structure and the distance between the gate position and the injection port, the injection component, flow rate and pressure of each injection position corresponding to the gate are accurately calculated, realizing differentiated control of the valve needle opening, so that molten plastic at different positions can be uniformly injected into the cavity in the same time, ensuring the stability of injection.

[0017] Optionally, methods for determining the valve needle opening include:

[0018] S20: Read plastic viscosity from product information;

[0019] S21: Determine the actual gate pressure by combining plastic viscosity, injection molding pressure requirements, and flow distance;

[0020] S22: Determine the full-open flow rate based on the actual gate pressure, plastic viscosity, and gate size;

[0021] S23: Determine the velocity difference by combining the fully open flow rate and the required flow rate;

[0022] S24: Match valve needle opening based on flow rate difference and plastic viscosity.

[0023] By adopting the above technical solution, the injection pressure required by the same injection port is used, and the actual gate pressure and full-open flow rate corresponding to the injection position are calculated by combining different flow distances. The valve needle opening is matched according to the difference between the full-open flow rate and the required flow rate, so that the actual flow rate of each gate tends to be consistent with the required flow rate.

[0024] Optionally, methods for modifying valve needle control commands include:

[0025] S30: Determine the filling percentage corresponding to the preset filling time based on the cavity structure, required flow rate, and injection volume;

[0026] S31: Match the corresponding reduction coefficient by filling ratio;

[0027] S32: Adjust the valve needle opening based on the reduction coefficient until the filling ratio is consistent with the preset full filling ratio;

[0028] S33: Modify valve needle control command by combining filling time and its corresponding corrected valve needle opening.

[0029] By adopting the above technical solution, since the injection speed during the injection process is not constant, as the proportion of molten plastic in the cavity gradually increases, it is necessary to gradually reduce the valve needle opening to ensure molding efficiency and product quality. A closed-loop correction method for the filling ratio and valve needle opening as the filling time increases has been established.

[0030] Optionally, executing valve needle control commands may include:

[0031] S40: Collect gate measurement pressure based on filling time;

[0032] S41: Determine the gate pressure corresponding to the filling time based on the plastic viscosity, actual gate pressure, and valve needle opening.

[0033] S42: Based on the same filling time, determine the pressure deviation by measuring the pressure at the gate and the actual pressure at the gate;

[0034] S43: When the pressure deviation exceeds the preset pressure threshold, the pressure difference is determined by combining the measured pressure at the gate and the actual pressure at the gate.

[0035] S44: Match the condensate layer thickness using pressure difference;

[0036] S45: Determine the ejection distance by combining the valve needle opening and the thickness of the condensate layer;

[0037] S46: The ejection of the valve needle is preset at the end of the valve needle based on the ejection distance control.

[0038] By adopting the above technical solution, the presence of a condensation layer at the gate is determined by the pressure deviation. The corresponding condensation layer thickness is matched with the pressure difference, and then the ejector pin is controlled to puncture the condensation layer at the gate, effectively restoring the effective flow cross-sectional area of ​​the gate.

[0039] Optionally, the following steps are included before collecting the pressure at the gate:

[0040] S50: Match the flow rate threshold and wall thickness threshold according to the plastic viscosity and gate size, and match the guide distance according to the valve needle opening;

[0041] S51: Obtain the cavity wall thickness corresponding to the injection position based on the cavity structure;

[0042] S52: Define the injection position corresponding to the demand flow rate being greater than the flow rate threshold and the cavity wall thickness being less than the corrected wall thickness threshold as an abnormal position;

[0043] S53: Control the ejection of the ejector pin based on abnormal position and guide distance.

[0044] By adopting the above technical solution, the flow rate threshold and wall thickness threshold are matched with the plastic viscosity and gate size to screen out the injection position that is prone to jet flow. At the corresponding position, the ejector pin is controlled to push out to the gate connection to guide the molten plastic, reduce the probability of high-speed molten plastic forming jet flow, and improve product quality.

[0045] Optionally, the ejection of the ejector pin, based on the abnormal location and the guide distance, includes the following:

[0046] S60: Get the ejector pin size;

[0047] S61: Determine the flow area by combining the ejector pin size and the gate size;

[0048] S62: Replace the gate size in S22 to S24 with the flow area to obtain the corrected valve needle opening;

[0049] S63: Correct the guide distance based on the corrected valve needle opening.

[0050] By adopting the above technical solution, since the ejector pin in the abnormal position is always located at the gate connection, the size of the ejector pin itself obstructs the gate flow area. Therefore, it is necessary to adjust the corresponding valve pin opening to compensate for this, so that the actual injection flow rate is consistent with the required flow rate. At the same time, the guide distance is corrected so that the ejector pin is always located at the gate connection to guide the colloid.

[0051] Optional methods for determining the ejection distance include:

[0052] S70: Determines whether the glue injection position is abnormal;

[0053] S710: If it is an abnormal location, the thickness of the condensate layer will be used as the ejection distance;

[0054] S711: If it is not an abnormal location, the top-out distance is calculated by summing the flow guide distance and the condensation layer thickness.

[0055] By adopting the above technical solution, the accuracy of the ejector pin action is improved by using different ejection distance calculation logics based on whether the injection position is abnormal. Since the ejector pin in the abnormal position is already located at the gate connection, while the ejector pin in the non-abnormal position is located inside the valve pin.

[0056] Secondly, the present invention provides a no-shear gate injection molding mold for automotive plastic spoilers, which adopts the following technical solution:

[0057] A no-cut gate injection molding mold for automotive plastic spoilers, applied to the first aspect of an automotive plastic spoiler no-cut gate injection molding mold, includes a mold body with a cavity, the cavity having an inclined surface adapted to the inclined surface of the spoiler, the mold body having an injection port for injecting molten plastic into the cavity and a branch gate perpendicular to and conforming to the inclined surface, the injection port, the branch gate and the cavity being sequentially connected, and the connection between the branch gate and the inclined surface being a smooth transition.

[0058] By adopting the above technical solution, the layout of the branch gate and the inclined surface of the cavity are vertically attached, which shortens the distance between the gate and the forming surface of the cavity, reduces the space in which molten plastic stays in the gate, and reduces the amount of gate solidified material remaining after injection molding.

[0059] Optionally, a valve needle for controlling the flow rate of the glue entering the branch gate is provided inside the branch gate.

[0060] By adopting the above technical solution, the effective flow cross-sectional area of ​​the branch gate can be precisely controlled by the axial displacement of the valve needle, so as to achieve dynamic control of the injection flow rate and velocity. At the same time, the melt connection between the gate and the cavity can be completely cut off, further suppressing the formation of gate solidified material.

[0061] Optionally, multiple branch gates are provided, and a manifold plate is provided between the branch gates and the injection port to guide the molten plastic to flow into all the branch gates.

[0062] By adopting the above technical solution, the melt from the injection port is evenly distributed to multiple branch gates using a manifold. The coordinated injection of multiple gates shortens the flow distance of the molten plastic in the cavity of a single gate and reduces the amount of residue in a single gate.

[0063] In summary, the present invention has at least one of the following beneficial technical effects:

[0064] Based on the cavity structure and the distance between the gate position and the injection port, the injection component, flow rate and pressure of each injection position are accurately calculated, realizing differentiated control of the valve needle opening, so that molten plastic at different positions can be uniformly injected into the cavity in the same time, ensuring the stability of injection.

[0065] The pressure deviation is used to determine whether there is a condensation layer at the gate. The pressure difference is combined with the corresponding condensation layer thickness, and then the ejector pin is controlled to puncture the condensation layer at the gate, effectively restoring the effective flow cross-sectional area of ​​the gate.

[0066] The pressure deviation is used to determine whether there is a condensation layer at the gate. The pressure difference is combined with the corresponding condensation layer thickness, and then the ejector pin is controlled to puncture the condensation layer at the gate, effectively restoring the effective flow cross-sectional area of ​​the gate. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the structure of an injection molding mold for a car plastic spoiler without a cut gate, as per this application.

[0068] Figure 2 This is a partial schematic diagram of an injection molding die for a car plastic spoiler that does not require a cut gate, as per this application.

[0069] Figure 3 yes Figure 1 A partial sectional view at point AA.

[0070] The parts referred to by the numbers in the above attached figures are as follows: 1. Mold body; 11. Cavity; 111. Inclined surface; 12. Injection gate; 13. Runner gate; 131. Valve pin; 14. Manifold. Detailed Implementation

[0071] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0072] This invention discloses a no-cut gate injection molding mold for automotive plastic spoilers.

[0073] Reference Figure 1 and Figure 2 A car plastic spoiler injection molding mold without gate cutting includes a mold body 1 having an injection port 12 and a runner 13, and a runner plate 14 is also installed inside the mold body 1.

[0074] Reference Figure 3 The mold body 1 has a cavity 11, and the cavity 11 has an inclined surface 111. The inclined surface 111 is adapted to the inclined surface of the baffle plate. The injection port 12 is used to inject molten plastic into the cavity 11. Multiple sprue gates 13 are provided, and each sprue gate 13 is vertical and attached to the inclined surface 111. The manifold 14 is installed between the injection port 12 and the sprue gates 13 and is used to guide the molten plastic to flow into all the sprue gates 13. The injection port 12, the manifold 14, the sprue gates 13 and the cavity 11 are connected in sequence. The connection between the sprue gate 13 and the inclined surface 111 is smooth. The injection port 12 is connected to the external injection equipment.

[0075] The valve needle 131 is inserted into the runner gate 13 and slides in a direction close to or away from the cavity 11 to control the flow rate of the runner gate 13.

[0076] During injection molding, the control valve needle 131 moves away from the cavity 11 to ensure complete communication between the manifold gate 13 and the cavity 11. Molten plastic is injected through the injection port 12 via the injection equipment. The molten plastic flows along the manifold plate 14 to all manifold gates 13, and then enters the cavity 11 through the manifold gates 13. During the injection process, the flow rate is controlled by the opening of the control valve needle 131. When the cavity 11 is full of molten plastic, the control valve needle 131 moves closer to the cavity 11 to completely isolate the manifold gates 13 from the cavity 11, reducing the probability of the molten plastic in the cavity 11 flowing back to the manifold gates 13 and reducing the generation of solidified material at the gate.

[0077] Based on the same inventive concept, embodiments of the present invention provide a method for controlling injection molding of automotive plastic spoilers without shearing the gate.

[0078] A method for controlling the injection molding of automotive plastic spoilers without gate shearing includes the following steps:

[0079] S10: Responds to the injection signal to obtain product information and mold structure.

[0080] The injection signal is a command signal used to trigger the valve needle 131 to open and inject molten plastic; it is triggered by the operator through the system operation terminal, for example, by the operator pressing a physical button.

[0081] Product information refers to the collection of molding process parameters and raw material characteristic parameters of automotive plastic spoilers, specifically including plastic viscosity, etc. The viscosity values ​​of raw materials at different temperatures and shear rates are tested using a capillary rheometer. Parameters are extracted from the product design drawings and integrated with the raw material viscosity values ​​to obtain product information, which is pre-entered into the system by the operator.

[0082] Mold structure refers to the overall geometric parameters of an injection mold, including cavity structure, gate location, gate size, etc. The mold structure is obtained by reading and integrating the mold design CAD drawings and is pre-entered into the system by the operator.

[0083] S11: Read the runner parameters, cavity structure, gate location and gate size from the mold structure.

[0084] The flow channel parameters refer to the three-dimensional geometric shape and size parameters of the manifold 14, including the size of the manifold 14, the inner wall roughness, etc. The size information is extracted from the three-dimensional design model of the manifold and the inner wall roughness is measured using an internal hole roughness meter. The flow channel parameters are then integrated and pre-integrated into the mold structure by the operator. The flow channel parameters are then directly read when in use.

[0085] The cavity structure refers to the three-dimensional geometric shape and dimensional parameters of the mold cavity 11, specifically including the contour surface of the cavity 11, the cavity wall thickness, etc.; dimensional information is extracted from the three-dimensional design model of the cavity, and the wall thickness values ​​of each region are obtained through the mesh generation function of the mold CAE simulation software. The cavity structure is then integrated and pre-integrated into the mold structure by the operator, and the cavity structure is directly read when used.

[0086] The gate location refers to the coordinates and relative position of the connection between the branch gate 13 and the cavity 11. The gate location is obtained by reading the data from the mold hot runner design drawing and then calibrating the data through the three-dimensional scanning data of the mold cavity 11. The gate location is then integrated into the mold structure in advance by the operator and can be directly read when in use.

[0087] The gate size refers to the geometric parameters at the connection between the runner gate 13 and the cavity 11, including the gate inner diameter and the gate length. It is extracted from the machining drawings of the runner gate 13, and then the extracted data is corrected by measuring with instruments such as a micron-level diameter gauge to finally obtain the gate size. The operator integrates it into the mold structure in advance, and the gate size is directly read when it is used.

[0088] S12: Determine the injection quantity and flow distance corresponding to the gate position based on the cavity structure.

[0089] The injection volume refers to the volume of the cavity that a single gate is responsible for filling, i.e., the volume of melt filling corresponding to that gate. Based on the volume calculation function of the three-dimensional cavity model, the filling area corresponding to each gate is divided and the volume of the area is calculated to obtain the injection volume corresponding to the gate position.

[0090] The flow distance refers to the effective distance that the molten plastic moves from the injection port 12 through the manifold 14 to the manifold gate 13, including the equivalent length of the bending path during the movement of the molten plastic. The flow process of the molten plastic is simulated by CAE flow simulation software, and the flow path length from the injection port 12 to each manifold gate 13 is extracted. For the bending path, the equivalent distance is calculated by the path integral method, and the final flow distance is obtained by summing them.

[0091] S13: Match the required flow rate based on the glue injection component.

[0092] The required flow rate refers to the volumetric flow rate of the melt at the gate required to ensure that the cavity area corresponding to the branch gate 13 is filled synchronously and without defects such as weld lines. The larger the amount of glue injected, the larger the required flow rate. The corresponding required flow rate is found from the flow rate correspondence table according to the amount of glue injected. The flow rate correspondence table is a data table that records different amounts of glue injected and their corresponding required flow rates. It is obtained by technicians through prior testing and recording.

[0093] S14: Determine the gate pressure requirement by combining the gate size, required flow rate, and product information.

[0094] The gate pressure requirement refers to the pressure value required at the gate to allow molten plastic to pass through the branch gate 13 at the required flow rate. The gate pressure requirement is calculated based on a modified Poiseuille's law, using the plastic viscosity obtained from the product information and the gate length and inner diameter obtained from the gate dimensions. The calculation formula is: P = 8ηLQ / πr 4 Where P is the gate pressure requirement, η is the plastic viscosity, L is the gate length, Q is the required flow rate, and r is the gate inner diameter.

[0095] S15: Determine the injection pressure requirement based on the runner parameters, gate pressure requirement, and flow distance.

[0096] Injection molding demand pressure refers to the output pressure of injection port 12 required to overcome the flow resistance of molten plastic moving from injection port 12 through manifold 14 to manifold gate 13 and to meet the gate demand pressure. The inner wall roughness is read from the flow parameters, and the resistance loss during the movement of molten plastic is calculated in combination with the flow distance. The summation with the gate demand pressure yields the demand pressure corresponding to each manifold gate 13. The largest demand pressure is selected from all demand pressures as the injection molding demand pressure to ensure that the actual pressure at each manifold gate 13 is not less than its corresponding demand pressure.

[0097] S16: Determine the valve needle opening corresponding to the gate location based on product information, injection molding pressure requirements, flow distance, and required flow rate.

[0098] The valve needle opening is the ratio of the axial displacement of the valve needle 131 to the maximum stroke of the valve needle 131, which directly affects the flow rate and pressure of the molten plastic. The specific method for determining the valve needle opening will be disclosed in detail in subsequent steps and will not be repeated here.

[0099] S17: Integrate the gate position and valve needle opening determination and execute the valve needle control command.

[0100] Valve needle control commands refer to the set of commands used to control the drive mechanism of valve needle 131 to perform the opening, closing, and opening adjustment actions of valve needle 131. They are generated by the system integrating the gate position and its corresponding valve needle opening information, and the commands are converted into control signals for the drive mechanism of valve needle 131 through PLC programming.

[0101] The method for determining the valve needle opening includes the following steps:

[0102] S20: Read the plastic viscosity from the product information.

[0103] Plastic viscosity refers to the melt viscosity of the raw material used in automotive plastic spoilers, that is, the ability of the melt to resist shear deformation. The melt viscosity values ​​at different temperatures and shear rates are tested by a capillary rheometer and integrated into the product information. When in use, the value can be directly read based on the current operating temperature and shear rate.

[0104] S21: Determine the actual gate pressure by combining the plastic viscosity, injection molding required pressure, and flow distance.

[0105] The actual gate pressure refers to the expected pressure value at each branch gate 13 when the injection molding demand pressure is executed, combined with the actual working conditions of plastic viscosity and flow distance. The actual gate pressure corresponding to the injection position is calculated by correcting the fluid resistance loss formula based on plastic viscosity, injection molding demand pressure and flow distance.

[0106] S22: Determine the full-open flow rate based on the actual gate pressure, plastic viscosity, and gate size.

[0107] Full-open flow rate refers to the volumetric flow rate of molten plastic through the gate at the actual gate pressure when the valve pin 131 is at its maximum opening. Its value is determined by the gate size, the actual gate pressure, and the plastic viscosity. During the mold debugging stage, the valve pin 131 is adjusted to the fully open state, and multiple simulation tests are conducted with different actual gate pressures, plastic viscosities, and gate sizes. The actual melt volume flow rate is collected to obtain the corresponding measured full-open flow rate. This allows the construction of a data model corresponding to the actual gate pressure, plastic viscosity, gate size, and full-open flow rate. The corresponding full-open flow rate is obtained by substituting the actual gate pressure corresponding to different injection positions into the data model.

[0108] S23: Determine the velocity difference by combining the fully open flow rate and the required flow rate.

[0109] The velocity difference refers to the difference between the fully open flow velocity and the required flow velocity. Its value reflects the degree of deviation between the flow velocity when the valve needle is fully open and the target flow velocity. The velocity difference is obtained by subtracting the fully open flow velocity from the required flow velocity.

[0110] S24: Match valve needle opening based on flow rate difference and plastic viscosity.

[0111] The corresponding valve needle opening is determined by looking up the opening correspondence table based on the flow rate difference and plastic viscosity. The opening correspondence table is a data table that records different flow rate differences and plastic viscosities and their corresponding valve needle openings. It is obtained by technicians through prior testing.

[0112] The method for correcting valve needle control commands includes the following steps:

[0113] S30: Determine the filling percentage corresponding to the preset filling time based on the cavity structure, required flow rate, and injection volume.

[0114] The filling time refers to the duration from the start of molten plastic injection into cavity 11; the filling time is directly set by the system; the filling ratio under different filling times is simulated in real time through cavity CAE flow simulation.

[0115] The filling ratio refers to the ratio of the actual volume of molten plastic filling to the total volume of the cavity within a certain filling time. The filling volume is obtained by multiplying the required flow rate and the cumulative filling time. The total cavity volume is read from the cavity structure, and the filling ratio corresponding to the filling time is obtained by quotienting the filling volume and the total cavity volume.

[0116] S31: Match the corresponding reduction coefficient by filling ratio.

[0117] The reduction factor is a proportional factor used to correct the valve needle opening and injection speed. Its value is negatively correlated with the filler ratio. The reduction factor corresponding to different filler ratios is calibrated through orthogonal experiments, and a correspondence table between filler ratio and reduction factor is established. The operator pre-enters the data into the system, and the corresponding reduction factor is directly read from the table according to the filler ratio when in use.

[0118] S32: Adjust the valve needle opening based on the reduction coefficient until the filling ratio is consistent with the preset full filling ratio.

[0119] The filling percentage refers to the target volume percentage when the cavity 11 is completely filled. It is usually set to 100%. For thick-walled areas that require pressure holding and shrinkage compensation, the filling percentage can be set between 95% and 98%, which is preset by the operator and entered into the system.

[0120] The corrected valve needle opening is obtained by multiplying the reduction coefficient with the valve needle opening. At the same time, the corresponding flow rate difference is read from the opening correspondence table in reverse according to the corrected valve needle opening. Then, the injection speed corresponding to the changed valve needle opening is obtained by combining the full-open flow rate. The filling ratio corresponding to the filling time is adjusted in real time based on the injection speed.

[0121] S33: Modify valve needle control command by combining filling time and its corresponding corrected valve needle opening.

[0122] The valve needle opening corresponding to the filling time is integrated into the valve needle control command, resulting in a valve needle control command with a dynamically changing valve needle opening that follows the increase of the filling time.

[0123] The steps involved in executing the valve needle control command are as follows:

[0124] S40: Collect gate measurement pressure based on filling time.

[0125] The gate measurement pressure refers to the actual pressure value at the gate during the injection process; the gate measurement pressure is obtained in real time by a miniature pressure sensor preset on the side wall of the gate.

[0126] S41: Determine the gate pressure corresponding to the filling time based on the plastic viscosity, actual gate pressure, and valve needle opening.

[0127] The gate designation pressure refers to the theoretical gate pressure value corresponding to the filling time under standard operating conditions, based on the current valve needle opening and the actual gate pressure. It serves as the benchmark value for judging pressure deviation. The gate designation pressure value corresponding to the filling time is calculated by combining the effective flow cross-sectional area corresponding to the valve needle opening, the actual gate pressure, and the plastic viscosity through a modified Poiseuille law.

[0128] S42: Based on the same filling time, the pressure deviation is determined by measuring the pressure at the gate and the actual pressure at the gate.

[0129] Pressure deviation refers to the ratio of the relative deviation between the measured pressure at the gate and the actual pressure at the gate. The pressure deviation is obtained by calculating the difference between the measured pressure at the gate and the actual pressure at the gate, and then quotienting the result of the difference with the actual pressure at the gate.

[0130] S43: When the pressure deviation is greater than the preset pressure threshold, the pressure difference is determined by combining the measured pressure at the gate and the actual pressure at the gate.

[0131] The pressure threshold refers to the maximum allowable pressure deviation under standard operating conditions, used to determine whether abnormal operating conditions occur at the gate. It is obtained through pressure deviation experiments during the mold debugging phase and is pre-entered into the system by the operator.

[0132] If the pressure deviation exceeds the pressure threshold, it means that the actual pressure condition at the gate deviates from the theoretical calculation value, indicating a problem of gate condensate blockage, which requires triggering a correction action.

[0133] The pressure difference is the difference between the measured pressure at the gate and the actual pressure at the gate. The pressure difference is calculated by subtracting the measured pressure at the gate from the actual pressure at the gate.

[0134] S44: Match the thickness of the condensate layer by pressure difference.

[0135] The thickness of the condensate layer refers to the thickness of the thin layer of solidified molten material formed on the inner wall of the gate due to contact with the low-temperature mold. The condensate layer reduces the effective flow cross-sectional area of ​​the gate and increases the flow resistance of the melt. The larger the pressure difference, the thicker the condensate layer. The corresponding condensate layer thickness can be found in the thickness correspondence table based on the pressure difference. The thickness correspondence table is a data table that records different pressure differences and their corresponding condensate layer thicknesses. It is obtained by technicians through prior testing and recording.

[0136] S45: Determine the ejection distance by combining the valve needle opening and the thickness of the condensate layer.

[0137] The ejection distance refers to the length from the starting position of the ejector pin to the point where it breaks through the condensation layer. The ejection distance varies under different circumstances, and the specific determination method will be disclosed in detail in subsequent steps, and will not be repeated here.

[0138] S46: The ejection of the ejector pin is preset at the end of the valve needle 131 based on the ejection distance control.

[0139] The ejector pin is a needle-shaped component that is pre-set at the end of the valve needle 131 and is used to pierce the condensation layer or guide the smooth flow of molten plastic. When not in operation, the ejector pin can be completely retracted into the interior of the valve needle 131. Its material is high-temperature resistant mold steel.

[0140] Before collecting pressure samples from the gate, the following steps are required:

[0141] S50: Match the flow rate threshold and wall thickness threshold according to the plastic viscosity and gate size, and match the guide distance according to the valve needle opening.

[0142] The flow velocity threshold refers to the critical volumetric flow velocity that determines whether molten plastic will form a jet flow. By simulating the melt flow state at different flow velocities through cavity CAE flow simulation, the critical flow velocity generated by the jet flow is calibrated, and a threshold correspondence table related to plastic viscosity and gate size is established. When using it, the flow velocity threshold is obtained from the threshold correspondence table according to the plastic viscosity and gate size.

[0143] The wall thickness threshold refers to the critical wall thickness value that determines whether molten plastic will form a jet flow. The critical wall thickness generated by the jet flow is calibrated by simulating the melt flow state at different flow rates through CAE flow simulation in the cavity, and integrated into the threshold correspondence table. When using it, the wall thickness threshold is obtained from the threshold correspondence table according to the plastic viscosity and gate size.

[0144] The guide distance refers to the minimum axial displacement of the ejector pin from the end of the valve pin 131 to the gate. The current displacement of the valve pin 131 is calculated by the valve pin opening and the known maximum stroke of the valve pin 131. Since the end of the valve pin 131 is flush with the gate when the valve pin 131 is fully closed, the result obtained by subtracting the maximum stroke of the valve pin 131 from the current displacement is the guide distance.

[0145] S51: Obtain the cavity wall thickness corresponding to the injection position based on the cavity structure.

[0146] Cavity wall thickness refers to the thickness of the inner wall of cavity 11 corresponding to the injection position, which is the target wall thickness of the product. Its value varies in different areas of cavity 11. The cavity wall thickness is obtained by extracting the wall thickness value of each area from the cavity 3D design model.

[0147] S52: Define the injection position corresponding to the demand flow rate being greater than the flow rate threshold and the cavity wall thickness being less than the corrected wall thickness threshold as an abnormal position.

[0148] If the required flow rate is greater than the flow rate threshold, it means that the molten plastic enters the cavity 11 at the injection point at too high a flow rate, which will impact the cavity 11 wall and form a jet flow.

[0149] If the cavity wall thickness is less than the corrected wall thickness threshold, it means that the cavity area corresponding to the injection point is a thin-walled area, the space for molten plastic to flow is narrow, and it is easy to form a jet flow.

[0150] An abnormal location is a glue inlet that simultaneously meets two conditions: the required flow rate is greater than the flow rate threshold and the cavity wall thickness is less than the corrected wall thickness threshold. The required flow rate and cavity wall thickness corresponding to each glue inlet location are compared with the corresponding thresholds, and glue inlet locations that simultaneously meet both conditions are defined as abnormal locations.

[0151] S53: Control the ejection of the ejector pin based on abnormal position and guide distance.

[0152] Based on the abnormal position, the ejector pin at the corresponding position is controlled to eject at a guiding distance. At this time, the end of the ejector pin is located at the connection between the branch gate 13 and the cavity 11. The molten plastic will flow along the ejector pin when it moves, thus ensuring smooth flow.

[0153] After the ejector pin is ejected based on the abnormal location and the guide distance, the following steps are included:

[0154] S60: Get the pin size.

[0155] Ejector pin dimensions refer to the diameter of the ejector pin end; the ejector pin dimensions are extracted from the ejector pin machining drawings and pre-entered into the system by the operator.

[0156] S61: Determine the flow area by combining the ejector pin size and the gate size.

[0157] The flow area refers to the effective cross-sectional area of ​​molten plastic passing through the gate when the ejector pin extends. The flow area is calculated by calculating the corresponding area based on the ejector pin size and the gate size, and then subtracting the corresponding area of ​​the gate from the corresponding area of ​​the ejector pin.

[0158] S62: Replace the gate size in S22 to S24 with the flow area to obtain the corrected valve needle opening.

[0159] The valve needle opening is recalculated by replacing the gate size in S22 to S24 with the flow area, and the corrected valve needle opening is only for abnormal positions.

[0160] S63: Correct the guide distance based on the corrected valve needle opening.

[0161] Based on the calculation method of the guide distance in S50, the corrected guide distance is recalculated with the corrected valve needle opening to ensure that when the ejector pin is ejected with the guide distance, the end of the ejector pin is always located at the gate connection.

[0162] The method for determining the ejection distance includes the following steps:

[0163] S70: Determine whether the injection position is abnormal based on the glue injection location.

[0164] Determine whether each injection point is an abnormal position. Since the ejector pin at an abnormal position is already extended, the distance to continue ejecting to break through the condensation layer is calculated differently than that for ejector pins at non-abnormal positions.

[0165] S710: If it is an abnormal location, the thickness of the condensate layer will be used as the ejection distance.

[0166] Since the ejector pin tip at the abnormal position is already located at the gate connection, the ejector pin tip is in contact with the condensate layer. It is only necessary to move the condensate layer by a distance corresponding to its thickness to break through it. Therefore, the condensate layer thickness is used as the ejection distance.

[0167] S711: If it is not an abnormal location, the top-out distance is calculated by summing the flow guide distance and the condensation layer thickness.

[0168] If it is not an abnormal position, the initial position of the ejector pin is consistent with the end position of the valve needle 131. At this time, the distance required for the ejector pin to break through the condensation layer is the distance between the end of the valve needle 131 and the gate combined with the thickness of the condensation layer. Therefore, the ejection distance is calculated by summing the flow guiding distance and the thickness of the condensation layer.

[0169] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the injection molding of automotive plastic spoilers without shearing the gate, characterized in that, include: S10: Responding to the injection signal, obtain product information and mold structure; S11: Read the runner parameters, cavity structure, gate position and gate size from the mold structure; S12: Determine the injection component and flow distance corresponding to the gate position according to the cavity structure. The flow distance refers to the effective movement distance of the molten plastic from the injection port (12) through the manifold (14) to the manifold gate (13), including the equivalent length of the bending path during the movement of the molten plastic; S13: Match the corresponding required flow rate based on the injection component; S14: Determine the gate required pressure by combining the gate size, required flow rate and product information; S15: Determine the injection required pressure according to the runner parameters, gate required pressure and flow distance; S16: Determine the valve pin opening corresponding to the gate position by combining the product information, injection required pressure, flow distance and required flow rate; S17: Integrate gate location and valve needle opening determination and execute valve needle control command; Methods for determining the valve needle opening include: S20: Read the plastic viscosity from the product information; S21: Determine the actual gate pressure by combining the plastic viscosity, injection molding required pressure, and flow distance; S22: Determine the full-open flow rate based on the actual gate pressure, plastic viscosity, and gate size; S23: Determine the flow rate difference by combining the full-open flow rate and the required flow rate; S24: Match the valve needle opening based on the flow rate difference and plastic viscosity; Methods for correcting valve needle control commands include: S30: Determine the filling percentage corresponding to the preset filling time based on the cavity structure, required flow rate, and injection component; S31: Match the corresponding reduction coefficient through the filling percentage; S32: Adjust the valve needle opening based on the reduction coefficient until the filling percentage is consistent with the preset full filling percentage; S33: Adjust the valve needle control command by combining the filling time and its corresponding adjusted valve needle opening. Executing valve needle control commands includes: S40: Collect gate measurement pressure based on filling time; S41: Determine the gate pressure corresponding to the filling time based on plastic viscosity, actual gate pressure, and valve needle opening; S42: Determine the pressure deviation based on the gate measurement pressure and actual gate pressure for the same filling time; S43: When the pressure deviation is greater than the preset pressure threshold, determine the pressure difference by combining the gate measurement pressure and actual gate pressure; S44: Match the condensate layer thickness by the pressure difference; S45: Determine the ejection distance by combining the valve needle opening and condensate layer thickness; S46: Control the ejection of the ejector pin preset at the end of the valve needle (131) based on the ejection distance; Before collecting pressure samples at the gate, the following steps are required: S50: Match the flow rate threshold and wall thickness threshold according to the plastic viscosity and gate size, and match the guide distance according to the valve needle opening. The flow rate threshold refers to the critical volume flow rate for determining whether the molten plastic will form a jet flow, and the wall thickness threshold refers to the critical wall thickness value for determining whether the molten plastic will form a jet flow. The guide distance refers to the minimum axial displacement of the ejector pin from the end of the valve needle (131) to the gate. S51: Obtain the cavity wall thickness corresponding to the injection position based on the cavity structure. S52: Define the injection position corresponding to the required flow rate being greater than the flow rate threshold and the cavity wall thickness being less than the corrected wall thickness threshold as an abnormal position. S53: Control the ejector pin ejection based on the abnormal position and the guide distance. After the ejector pin is ejected based on the abnormal location and guide distance, the following is included: S60: Obtain the ejector pin size; S61: Determine the flow area by combining the ejector pin size and the gate size. The flow area refers to the effective cross-sectional area of ​​the molten plastic flowing through the gate when the ejector pin extends; S62: Replace the gate size in S22 to S24 with the flow area to obtain the corrected valve pin opening; S63: Correct the guide distance based on the corrected valve pin opening. Methods for determining the ejection distance include: S70: Determine whether the injection position is abnormal; S710: If it is an abnormal position, use the condensation layer thickness as the ejection distance; S711: If it is not an abnormal position, calculate the ejection distance by summing the flow guide distance and the condensation layer thickness.

Images