High-consistency molding method for injection molding product

Abstract

The invention provides a high-consistency molding method of an injection molding product, and aims to solve the technical problem that a constant-pressure and pressure-maintaining mode of an existing injection molding process only depends on a single-point pressure signal and cannot sense density distribution and local shrinkage of a mold cavity in real time, so that the dimensional precision of a precise injection molding product is poor. The method comprises the steps that through CAE mold flow simulation, the optimal specific volume of a product is set with the minimum volume shrinkage standard deviation as the target; ultrasonic sensing units are mounted at a pouring gate, the middle part and a flowing tail end of a mold cavity to detect real-time sound velocity; the temperature and pressure drop of each point in the pressure maintaining process are confirmed in a CAE simulation mode; the inherent adiabatic bulk modulus of the polymer is combined to realize direct detection of the multi-point specific volume of the polymer melt; and the dwell pressure required by the equal specific volume is calculated in real time by using the corrected polymer double-domain Tit equation, so that the equal specific volume control of the melt is realized in the whole dwell stage. According to the method, on the basis that a product cavity is not changed, uniform shrinkage of all areas of the product is achieved through pressure maintaining and stepless pressure regulation, and the size precision of the product is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer material processing, specifically relating to a high-consistency molding method for injection molded products. The system is based on the online solution of the polymer PVT equation of state to obtain the holding pressure, thereby achieving a constant specific volume of the product during the molding process, reducing warpage and dimensional fluctuations, and achieving high-quality consistency of injection molded products. Background Technology

[0002] Injection molding is an important molding method for processing polymer materials. A typical process flow involves the following steps: mold closing, injection, pressure holding, cooling, plasticizing, mold opening, and ejection. During the pressure holding and cooling stage, the specific volume of the melt continuously changes as the temperature decreases and the pressure is released. The PVT (pressure-specific volume-temperature) characteristics of polymer materials determine their compression and thermal shrinkage behavior. If the specific volume of different areas of the mold cavity is different at the moment of freezing, the part is prone to warping, residual stress, and dimensional deviations. Therefore, maintaining a uniform specific volume of the melt in the mold cavity through precise pressure holding control before gate sealing is the key to obtaining products with high dimensional accuracy.

[0003] Currently, the industry commonly uses constant or segmented holding pressure before the gate is sealed to compensate for volume shrinkage. To truly minimize product warpage, the essence is to keep the specific volume of the melt constant within the mold cavity. However, as the dimensional accuracy of injection molded products continues to improve and their structures become more complex, the traditional constant pressure holding control method of injection molding machines is prone to causing large residual stress gradient differences, which cannot meet the dimensional accuracy requirements of the products.

[0004] To address this challenge, CN101234524A proposed a method and apparatus for online testing of the polymer pressure-specific volume-temperature relationship. While successful, this method suffers from several drawbacks. When the clamping force of the injection molding machine is too high, the melt filling and expansion behavior cannot be reflected on the moving mold platen, leading to a significant decrease in the accuracy of the displacement sensor. Furthermore, if the projected area of ​​the product in the mold direction is too large, the cavity pressure will be excessive, causing abnormal mold bulging. Conversely, if the projected area is too small, the displacement of the moving mold platen will be minimal, both resulting in fluctuations in the accuracy of the displacement sensor and affecting specific volume measurement. CN116353007B proposed an intelligent pressure holding control method for hydraulic injection molding machines: it uses the peak clamping force and the V / P switching point of the current cycle to predict the switching time of the next cycle, and calculates the holding pressure of the next cycle based on the injection pressure data, thereby correcting the holding pressure curve online. Although this scheme introduces cycle adaptive logic, it still relies on a single-point pressure signal in the mold cavity, cannot detect local density changes caused by temperature gradients, still requires multiple trial moldings to converge, and has limitations in the production of thick-walled or high-optical-quality parts. Summary of the Invention

[0005] This invention aims to solve the technical problem of poor dimensional accuracy in precision injection molded products caused by the inability to detect mold cavity density distribution and local shrinkage in real time due to the reliance on single-point pressure signals in existing constant pressure holding methods. The invention proposes a high-consistency molding method for injection molded products. This method directly detects the specific volume of the polymer melt at multiple points by installing ultrasonic sensing units at the mold cavity gate, middle, and flow end. It also uses a modified polymer pressure equation to calculate the holding pressure required for constant specific volume in the injection molding machine in real time, enabling constant specific volume control of the melt throughout the holding stage. This further promotes uniform shrinkage in all areas of the product, thereby improving dimensional accuracy. The implementation steps of this method are as follows:

[0006] S1: Based on the CAE simulation results of the product, and taking the minimum standard deviation of the product volume shrinkage rate during the pressure holding stage as the criterion, set the target specific volume V of the product during the pressure holding stage. tar (t).

[0007] S2: Install an ultrasonic transducer on the outside of the mold, and install ultrasonic probes at the corresponding mold cavity gate area, middle, and flow end positions; after installation, check the sensor wiring and power supply. Initialize the equipment upon startup, setting the injection molding process according to pre-defined molding parameters, including injection temperature, injection speed, V / P switching point, and holding pressure.

[0008] S3: Entering the initial data acquisition phase, the controller synchronously records the initial holding pressure P0 (MPa) and the sound velocity c at various points throughout the entire process from the melt entering the cavity to the end of cooling, with a refresh cycle of no more than 5ms. i (t)(m / s), where i=1,2,3, representing the gate area, middle section, and flow end, respectively.

[0009] S4: Using the actual mold and cooling water system as a model, perform CAE simulation analysis on the product filling behavior and record the melt temperature T at each point during the pressure holding process. i Calculate the pressure loss ΔP of the melt from the flow channel to each point based on the change in (t)(℃). ri (MPa).

[0010] S5: Based on the initial holding pressure setting P0, and taking into full account the flow channel pressure loss due to machine responsiveness, calculate the cavity pressure P inside the mold. mi，0 (MPa), the calculation formula is as follows:

[0011] P mi,0 (t)=P0-ΔP ri (1)

[0012] S6: Based on the inherent properties of polymer materials, namely the thermal bulk modulus K s (T, P) m(MPa), based on the product temperature and pressure data, ultrasonic testing is used to add information about the internal flow of the melt, thereby directly detecting the melt specific volume V at various points in the mold cavity. i (cc / g), the calculation formula is as follows:

[0013]

[0014] S7: To achieve overall pressure holding control, different weights are assigned to each region. i (∑w i =1), calculate the average specific volume And calculate the specific volume variance. The calculation formula is as follows:

[0015]

[0016]

[0017] S8: Taking into full account the increased warping caused by uneven shrinkage in local areas of the product, the two major requirements of "small overall shrinkage of the product" and "uniform local shrinkage" are integrated into a real-time controllable scalar, and a real-time dual objective function J(t)(cc / g) is constructed, the calculation formula of which is as follows:

[0018] J(t)=α|V(t)-V tar |+βσ V (t) (5)

[0019] Where α and β are adjustable weighting coefficients.

[0020] S91: Determine whether the δ temperature of each region is higher than the curing temperature T by simulating the temperature at each point. f If T i (t)>T f Then this region is the melting zone, let δ i =m(melt); if T i (t)≤T f Then the region is a solid region, δ i =s(solid)

[0021] S92: Calculate the specific volume under δ in each region to achieve the target value V. tar Local demand pressure (t) (MPa), the calculation formula is as follows:

[0022]

[0023] in, Specific volume at 0 MPa for molten / solid state; B m,s (t) represents the molten / solid Tait modulus.

[0024] If the region is a molten zone B m (t) Select the melting zone Tait coefficient;

[0025] If the region is a solid region B s (t) Select the solid-state domain Tait coefficient.

[0026] S93: By combining the local demand pressures at three points with the weights of each domain, the total cavity demand pressure P is synthesized. ff (t)(MPa), its calculation formula is as follows:

[0027]

[0028] S10: If the specific volume error is directly converted into pressure during the pressure holding stage, it will lead to insufficient compensation in the low-pressure area, overshoot oscillation in the high-pressure area, slow convergence and instability. Therefore, a local compression sensitivity S is introduced. i (t)(cc / (g·MPa)), and normalize it to convert it into the theoretical pressure compensation amount ΔP(t)(MPa) that needs to be applied. The calculation formula is as follows:

[0029]

[0030]

[0031]

[0032] This method controls the sensitivity to update in real time with temperature and pressure, automatically amplifies compensation in the low-pressure range, and automatically weakens compensation in the high-pressure range, quickly eliminating specific volume error and achieving real-time correction under various operating conditions.

[0033] S11: Considering the pressure drop from the injection molding machine screw pressure to the mold cavity, the total cavity required pressure P ff The pressure (t) and the theoretical pressure compensation ΔP(t) are combined after proportional-integral adjustment to form the current cycle injection molding machine holding pressure command P. cmd (MPa), the calculation formula is as follows:

[0034]

[0035] Among them, K p K is the pressure compensation coefficient. i K is the steady-state error coefficient; w This is the forced homogenization coefficient.

[0036] S12: If J(t) exceeds the set threshold 5 times consecutively, the controller automatically adjusts w. i K p K i Kw If the problem persists, a shutdown alarm will be issued.

[0037] Furthermore, the monitoring points of the sensing unit in step S2 are not limited to the gate, the middle, and the end of the flow; they can be extended to 5 or 7 points, as long as ∑w is guaranteed. i =1 is sufficient.

[0038] Furthermore, the weight w set for each domain in step S7 can be set based on the CAE simulation results of the product by judging the weight of different regions on the product's volume shrinkage rate and warpage deformation.

[0039] Furthermore, the total cavity demand pressure P in step S93 ff (t), if the temperature at each point is higher than the curing temperature T f Since all three points are molten zones, the calculation formula can be simplified to:

[0040]

[0041] in, The average temperature is calculated using the following formula:

[0042]

[0043] Overall, the high-consistency molding method for injection molded products conceived in this invention achieves synergistic minimization of melt average specific volume and specific volume variance by calculating specific volume at multiple points and introducing the PVT equation into the pressure holding closed loop. This significantly improves the consistency of molding dimensions and reduces warpage. Furthermore, by installing parameter sensors at various locations, key parameters can be extracted, which is beneficial for high-accuracy analysis of the injection molding process and provides reliable data for intelligent injection molding. Attached Figure Description

[0044] Figure 1 This is a flowchart of a stepless pressure-variable injection molding method for highly consistent injection molded products according to the present invention;

[0045] Figure 2 This is a schematic diagram showing the installation position of the sensing unit in the control system of the present invention;

[0046] Figure 3 This is a pressure holding curve for achieving constant volume pressure holding in an example of the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the invention described below can be combined with each other as long as they do not complement each other.

[0048] To address the technical problem that existing constant-pressure holding processes in injection molding rely solely on single-point pressure signals and cannot detect the density distribution of the mold cavity in real time, resulting in difficulty in significantly reducing warpage in thick-walled and optical-grade parts, a high-consistency molding method for injection molded products is proposed. This method achieves multi-point specific volume detection by installing ultrasonic sensing units in three regions of the mold cavity, and uses a modified polymer dual-domain Tait equation to calculate the holding pressure required for equal specific volume in real time, enabling the melt to shrink uniformly throughout the holding stage.

[0049] The present invention will now be described in detail with reference to the embodiments.

[0050] like Figure 1 As shown, a method for high-consistency injection molding of products includes the following steps:

[0051] S1: Based on the CAE mold flow simulation results of the multi-process product, and taking the minimum standard deviation of the product volume shrinkage rate during the pressure holding stage as the criterion, set the target specific volume V of the product during the pressure holding stage. tar (t).

[0052] S2: Install an ultrasonic transducer outside the mold, and install ultrasonic probes at the corresponding mold cavity gate area, middle, and flow end positions; such as Figure 2 As shown, after installation, check the sensor wiring and power supply. Power on the equipment and initialize it, setting the injection molding process according to pre-defined molding parameters, including injection temperature, injection speed, V / P switching point, and holding pressure.

[0053] S3: Start trial molding and enter the initial data acquisition stage. The controller synchronously records the initial holding pressure P0 (MPa) and the sound velocity c at various points throughout the entire process from the melt entering the cavity to the end of cooling, with a refresh cycle of no more than 5ms. i (t)(m / s), where i=1,2,3, representing the gate area, middle section, and flow end, respectively.

[0054] S4: Using the actual mold and cooling water circuit as the mold flow analysis model, CAE simulation analysis was performed on the product filling behavior, and the melt temperature T at each point during the holding pressure process was recorded. i Calculate the pressure loss ΔP of the melt from the flow channel to each point based on the change in (t)(℃). ri (MPa).

[0055] S5: Based on the initial holding pressure setting P0, and taking into full account the flow channel pressure loss due to machine responsiveness, calculate the cavity pressure P at each point within the mold. mi，0 (MPa), the calculation formula is as follows:

[0056] P mi,0 (t)=P0-ΔP ri

[0057] S6: Before the experiment, the adiabatic bulk modulus K of the polymer material under the influence of different temperatures and pressures was obtained by testing according to ISO 17744 standard. s (MPa), forming the inherent property equation of the polymer, and confirming the adiabatic bulk modulus of the current state based on the temperature and cavity pressure at each point; adding information on the internal flow of the melt through ultrasonic testing, and finally directly measuring the specific volume V based on the ultrasonic velocity and adiabatic bulk modulus. i (cc / g), the calculation formula is as follows:

[0058]

[0059] S7: To achieve overall pressure holding control and fully consider the impact of shrinkage in different regions on warping deformation, a regional weight w is set for each region. i (∑w i =1), calculate the average specific volume And calculate the specific volume variance. The calculation formula is as follows:

[0060]

[0061] S8: Taking into full account the aggravated local uneven shrinkage and warping caused by factors such as uneven wall thickness of the product, structural design, and uneven cooling of the mold, the two major requirements of "small overall shrinkage of the product" and "local uniform shrinkage" are integrated into a real-time controllable scalar, and a real-time dual objective function J(t)(cc / g) is constructed, the calculation formula of which is as follows:

[0062] J(t)=α|V(t)-V tar |+βσ V (t)

[0063] The average term controls overall dimensional shrinkage and reduces weight fluctuations; the variance term homogenizes the density within the cavity, weakening local uneven shrinkage. α and β are adjustable weighting coefficients. α adjusts the average specific volume to the target, and is commonly used with α = 1; β is used to suppress intracavity inhomogeneity, and is commonly used with β = 0.5-1.

[0064] S91: As can be seen from the two-domain Tait equation, the coefficients selected are different for molten and solid polymers. Therefore, the first step is to determine whether the δ temperature of each region is higher than the curing temperature T. f If T i (t)>T f Then this region is the melting zone, let δ i =m(melt); if T i (t)≤T f Then the region is a solid region, δ i = s(solid).

[0065] S92: To ensure the melt maintains pressure at a constant specific volume within the mold cavity, therefore, based on the current zone temperature T... i Calculate the specific volume under δ in each region to achieve the target value V tar (t) Local cavity demand pressure The calculation formula is as follows:

[0066]

[0067] in, Specific volume at 0 MPa for molten / solid state; B m,s (t) is the melt / solid Tait modulus, which can be calculated based on the polymer PVT characteristics.

[0068] If the region is a molten zone B m (t) Select the melting zone Tait coefficient;

[0069] If the region is a solid region B s (t) Select the solid-state domain Tait coefficient.

[0070] S93: By combining the local cavity demand pressure at three points with the weights of each domain, the total cavity demand pressure P is synthesized. ff (t), its calculation formula is as follows:

[0071]

[0072] S10: During the holding pressure stage, the relationship between melt specific volume and pressure follows the Tait exponential equation. If the specific volume error is directly converted into pressure, it will lead to insufficient compensation in the low-pressure zone, overshoot oscillation in the high-pressure zone, slow convergence, and instability. Therefore, a local compression sensitivity S is introduced. i (t)(cc / (g·MPa)), and normalize it to convert it into the theoretical pressure compensation amount ΔP(t)(MPa) that needs to be applied. The calculation formula is as follows:

[0073]

[0074]

[0075]

[0076] Sensitivity mapping ensures real-time matching between pressure compensation and material compressibility, as cooling progresses. i As the pressure decreases, ΔP naturally decreases, thus avoiding excessive pressure holding.

[0077] S11: Given the total cavity demand pressure and the theoretical pressure compensation, the total cavity demand pressure P ffThe pressure (t) and the theoretical pressure compensation ΔP(t) are combined through proportional-integral adjustment to form the current cycle pressure holding command pressure P. cmd The calculation formula is as follows:

[0078]

[0079] Among them, K p The pressure compensation coefficient is taken as 0.6-0.9; K i The steady-state error coefficient is used to eliminate steady-state error. K w To enforce homogenization, additional pressure is applied as variance increases, ranging from 0.5 to 1.0 MPa / (cm²). 3 ·g -1 ).

[0080] S12: If J(t) exceeds the set threshold 5 times consecutively, the controller automatically adjusts w. i K p K i K w It achieves adaptive convergence; if it still fails to converge, it issues a shutdown alarm.

[0081] Furthermore, the monitoring points of the sensing unit in step S2 are not limited to the gate, the middle, and the end of the flow; they can be extended to 5 or 7 points, as long as ∑w is guaranteed. i =1 is sufficient.

[0082] Furthermore, the weight w set for each domain in step S7 can be set based on the CAE simulation results of the product, by judging the weight of different regions on the product's volume shrinkage rate and warpage deformation.

[0083] Furthermore, the total cavity demand pressure P in step S93 ff (t), if the temperature at each point is higher than the curing temperature T f Since all three points are molten zones, the calculation formula can be simplified to:

[0084]

[0085] in, The average temperature is calculated using the following formula:

[0086] The present invention will now be described in detail with reference to the embodiments.

[0087] Example

[0088] The following example, using the constant volume pressure holding control of a thick-walled flat mold, illustrates the specific implementation measures of this invention. The injection molding machine used in this embodiment is a Changfeiya VE1200, with a cavity size of 120×90×6mm. The material selected is polycarbonate (PC). Specific process parameters and calculated process control parameters are shown in the table below:

[0089]

[0090] This embodiment takes the pressure calculation of the pressure holding command when the pressure holding time is 3 seconds as an example.

[0091] Based on a thick-walled flat mold, the filling flow simulation of the product was conducted. Through DOE simulation analysis of barrel temperatures (260℃, 270℃, 280℃), injection speeds (110cc / s, 120cc / s, 130cc / s), and holding pressures (40MPa, 45MPa, 50MPa), it was determined that the minimum standard deviation of the volume shrinkage rate was 0.0156 at a barrel temperature of 270℃, an injection speed of 120cc / s, and a holding pressure of 45MPa. Using this process parameter as the target, the target specific volume V was confirmed. tar It is 0.895cc / g.

[0092] The temperatures of each region obtained are: T G (3) = 256℃, T M (3) = 250℃, T E (3) = 235℃; Pressure: P G (3) = 42 MPa, P M (3) = 39 MPa, P E (3) = 31 MPa; the speed of sound is: c G (3) = 995.37 m / s, c M (3) = 977.61 m / s, c E (3) = 933.8 m / s;

[0093] The melt density ρ of each region of the cavity is obtained based on the formula for calculating melt density and specific volume. G (3) ρ M (3) ρ E (3), and the specific volume V of each region of the cavity G (3) V M (3) V E (3):

[0094]

[0095] Based on the CAE simulation results of the product, the warping deformation of each region of the product is L. G =0.331mm, L M =0.551mm, LE =0.220mm, therefore the weight w of each region of the cavity is set. G :w M :w E =0.3:0.5:0.2, calculate the average specific volume of the cavity. :

[0096]

[0097] And calculate the specific volume variance. :

[0098]

[0099] Constructing a real-time bi-objective function J(3):

[0100] J(3)=α|V(3)-V tar |+βσ V (3) = 0.031 cc / g

[0101] Based on the current regional temperature T G T M T E Calculate the specific volume under δ in each region to achieve the target value V tar Local demand pressure And calculate the total cavity required pressure P ff (3):

[0102]

[0103] Introducing local compression sensitivity S G (3) S M (3) S E (3), and normalize it to convert it into the theoretical pressure compensation amount ΔP(3) that needs to be applied:

[0104]

[0105] The total cavity demand pressure P ff (3) and the theoretical pressure compensation amount ΔP(3) are combined after proportional-integral adjustment to form the current cycle pressure holding command pressure P. cmd (3):

[0106]

[0107] Calculate the required pressure P at each time point during the entire pressure holding process according to the above procedure. cmd (t), such as Figure 3As shown in the figure. Actual production tests were conducted using the aforementioned pressure curves. The final product quality, compared with that obtained using the constant pressure holding method, showed the following results: overall product warpage deformation improved by 41.20%, and volume shrinkage rate improved by 26.96%.

[0108] Constant pressure holding Method of the present invention Warpage / mm 0.551 0.324 Volume shrinkage rate / % 3.527 2.576

Claims

1. A method for high-consistency molding of injection molded products, characterized in that... The steps are as follows: S1: Based on the CAE simulation results of the product, and taking the minimum standard deviation of the product volume shrinkage rate during the pressure holding stage as the criterion, set the target specific volume V of the product during the pressure holding stage. tar (t); S2: Install an ultrasonic transducer on the outside of the mold, and install ultrasonic probes at the corresponding mold cavity gate area, middle and flow end positions respectively; After installation, check the sensor wiring and power supply, power on the equipment and initialize it. Set the injection molding process according to the pre-defined molding parameters, including injection temperature, injection speed, V / P switching point, holding pressure, etc. S3: Entering the initial data acquisition phase, the controller synchronously records the initial holding pressure P0 (MPa) and the sound velocity c at various points throughout the entire process from the melt entering the cavity to the end of cooling, with a refresh cycle of no more than 5ms. i (t)(m / s), where i=1,2,3, representing the gate area, middle section, and flow end respectively; S4: Using the actual mold and cooling water system as a model, perform CAE simulation analysis on the product filling behavior and record the melt temperature T at each point during the pressure holding process. i Calculate the pressure loss ΔP of the melt from the flow channel to each point based on the change in (t)(℃). ri (MPa); S5: Based on the initial holding pressure setting P0, and taking into full account the flow channel pressure loss due to machine responsiveness, calculate the cavity pressure P inside the mold. mi，0 (MPa), the calculation formula is as follows: P mi,0 (t)=P0-ΔP ri S6: Based on the inherent properties of polymer materials and the product temperature and pressure data, ultrasonic testing is used to add information about the internal flow of the melt, thereby directly detecting the melt specific volume V at various points in the mold cavity. i (cc / g), the calculation formula is as follows: S7: To achieve overall pressure holding control, different weights are assigned to each region. i (∑w i =1), calculate the average specific volume And calculate the specific volume variance. The calculation formula is as follows: S8: Taking into full account the increased warping caused by uneven shrinkage in local areas of the product, the two major requirements of "small overall shrinkage of the product" and "uniform local shrinkage" are integrated into a real-time controllable scalar, and a real-time dual objective function J(t)(cc / g) is constructed, the calculation formula of which is as follows: J(t)=α|V(t)-V tar |+βσ V (t) Where α and β are adjustable weighting coefficients; S91: Determine whether the δ temperature of each region is higher than the curing temperature T by simulating the temperature at each point. f If T i (t)>T f Then this region is the melting zone, let δ i =m(melt); if T i (t)≤T f Then the region is a solid region, δ i = s(solid); S92: Calculate the specific volume under δ in each region to achieve the target value V. tar The local demand pressure P of (t) i ff (t)(MPa), its calculation formula is as follows: in, Specific volume at 0 MPa for molten / solid state; B m,s (t) represents the molten / solid Tait modulus; If the region is a molten zone B m (t) Select the melting zone Tait coefficient; If the region is a solid region B s (t) Select the solid-state domain Tait coefficient; S93: By combining the local demand pressures at three points with the weights of each domain, the total cavity demand pressure P is synthesized. ff (t)(MPa), its calculation formula is as follows: S10: If the specific volume error is directly converted into pressure during the pressure holding stage, it will lead to insufficient compensation in the low-pressure area, overshoot oscillation in the high-pressure area, slow convergence and instability. Therefore, a local compression sensitivity S is introduced. i (t)(cc / (g·MPa)), and normalize it to convert it into the theoretical pressure compensation amount ΔP(t)(MPa) that needs to be applied. The calculation formula is as follows: This method controls the sensitivity to update in real time with temperature and pressure, automatically amplifies compensation in the low-pressure section and automatically weakens compensation in the high-pressure section, quickly eliminates specific volume error, and achieves real-time correction for each working condition. S11: Considering the pressure drop from the injection molding machine screw pressure to the mold cavity, the total cavity required pressure P ff The pressure (t) and the theoretical pressure compensation ΔO(t) are combined through proportional-integral adjustment to form the current cycle injection molding machine holding pressure command P. cmd (MPa), the calculation formula is as follows: Among them, K p K is the pressure compensation coefficient. i K is the steady-state error coefficient; w This is the forced homogenization coefficient; S12: If J(t) exceeds the set threshold 5 times consecutively, the controller automatically adjusts w. i K p K i K w If the problem persists, a shutdown alarm will be issued.

2. The injection molding method for high consistency of injection molded products according to claim 1, characterized in that: In step S2, the number of sensing unit monitoring points is expanded to 5 or 7, and it is necessary to ensure that ∑w i =1.

3. The high-consistency molding method for injection molded products according to claim 1, characterized in that: In step S7, the weights w set for each domain are determined based on the CAE simulation results of the product by judging the weights of different regions on the product's volume shrinkage rate and warpage deformation.

4. The high-consistency molding method for injection molded products according to claim 1, characterized in that: The full cavity demand pressure P in step S93 ff (t), if the temperature at each point is higher than the curing temperature T f If all three points are in the molten zone, the calculation formula can be simplified to: in, The average temperature is calculated using the following formula:

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