Aluminum alloy semi-solid die-casting forming method and system

Abstract

The invention discloses an aluminum alloy semi-solid die-casting forming method and system, relates to the technical field of metal processing, and aims at solving the problems that in an existing semi-solid die-casting technology, the slurry solid fraction fluctuation is large, the structure uniformity is poor, and die-casting control is not in place. The method comprises the following steps: preparing an aluminum alloy raw material, carrying out refining modification treatment on the aluminum alloy raw material, and carrying out dynamic stage temperature control stirring to complete preparation treatment of semi-solid slurry, so as to obtain semi-solid aluminum alloy slurry, carrying out preheating treatment on a die-casting die, transferring and injecting the semi-solid aluminum alloy slurry into a pressure chamber of the die-casting die, and constructing an automatic die-casting program. Full-period die-casting control is conducted on the semi-solid aluminum alloy slurry in the pressure chamber, solution treatment and aging heat treatment are conducted on the aluminum alloy casting subjected to full-period die-casting control, the respective treatment processes are supervised and intervened, and then the final aluminum alloy casting forming part is obtained, so that the compactness and mechanical property of the casting are effectively improved, and the casting quality is improved. And high-quality casting of castings is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal processing, and specifically to a method and system for semi-solid die casting of aluminum alloy. Background Technique

[0002] In the traditional aluminum alloy die casting process, the high-speed filling of liquid metal is likely to entrap gas, resulting in a high porosity and poor mechanical properties inside the aluminum alloy castings. Moreover, shrinkage porosity defects are likely to occur during the solidification and shrinkage of the liquid metal. The development of semi-solid die casting technology has solved this problem. However, when obtaining semi-solid slurry through mechanical stirring or electromagnetic stirring in semi-solid die casting technology, there are problems such as large fluctuations in the solid phase ratio of the slurry, poor tissue uniformity, and inadequate die casting control, which affect the stability and mechanical properties of the formed parts of aluminum alloy castings. How to solve these problems encountered in the semi-solid die casting process of aluminum alloy has become an urgent task in the field of metal processing. Summary of the Invention

[0003] In order to solve the above problems, the purpose of the present invention is to provide a method and system for semi-solid die casting of aluminum alloy.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for semi-solid die casting of aluminum alloy includes the following steps:

[0005] Step S1: Prepare aluminum alloy raw materials according to a preset formula ratio, and perform semi-solid slurry preparation treatment on the aluminum alloy raw materials through refinement modification treatment and dynamic staged temperature control stirring to obtain semi-solid aluminum alloy slurry;

[0006] Step S2: Perform preheating treatment on the die casting mold, transfer and inject the semi-solid aluminum alloy slurry into the pressure chamber of the die casting mold, construct an automated die casting program, and perform full-cycle die casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die casting program;

[0007] Step S3: Perform solution treatment and aging heat treatment on the aluminum alloy casting after full-cycle die casting control, and supervise and intervene in the treatment processes of the solution treatment and aging heat treatment to obtain the final formed part of the aluminum alloy casting.

[0008] Furthermore, the process of preparing aluminum alloy raw materials according to a preset formula ratio and performing semi-solid slurry preparation treatment on the aluminum alloy raw materials through refinement modification treatment and dynamic staged temperature control stirring to obtain semi-solid aluminum alloy slurry includes:

[0009] Based on the mechanical properties of the target casting, prepare aluminum alloy raw materials according to the preset formula ratio;

[0010] Select the types of refiners and modifiers;

[0011] The refinement modification treatment is specifically divided into a refinement operation and a modification operation;

[0012] The refinement operation is carried out on the aluminum alloy raw material by a refiner;

[0013] The modification operation is carried out on the aluminum alloy raw material after the refinement operation by a modifier;

[0014] The modification effect of the aluminum alloy material after the modification operation is evaluated. When the modification operation is successfully completed, the dynamic stage temperature control stirring is continued to obtain the final semi-solid aluminum alloy slurry.

[0015] Further, the process of the dynamic stage temperature control stirring includes:

[0016] The aluminum alloy slurry after refinement and modification is stirred by electromagnetic stirring + mechanical stirring. According to the stage of the aluminum alloy slurry, the stirring temperature and stirring parameters are dynamically changed. Among them, the stage of the aluminum alloy slurry includes the pure liquid stage and the semi-solid stage. The real-time temperature of the aluminum alloy slurry in the semi-solid stage is recorded and maintained at this real-time temperature. The solid-liquid ratio of the aluminum alloy slurry in the semi-solid stage is synchronously measured to obtain the corresponding solid phase fraction, which is denoted as G-score;

[0017] A solid phase compliance fraction is set and denoted as Db-Score;

[0018] When G-score≥Db-Score, the dynamic stage temperature control stirring is completed;

[0019] When G-score<Db-Score, a temperature control range is set. Within the temperature control range, the real-time temperature in the stirring environment of the aluminum alloy slurry is adjusted by increasing or decreasing at a fixed value, and the aluminum alloy slurry is stirred to obtain the real-time solid phase fraction of the aluminum alloy slurry until the solid phase fraction meets the expectation, and then the stirring and temperature adjustment are stopped.

[0020] Further, the process of preheating the die-casting mold and transferring the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold includes:

[0021] The three-dimensional modeling of the die-casting mold is carried out to construct the corresponding three-dimensional solid structure model, and the die-casting mold is divided into a complex structure area and a general structure area;

[0022] The preheating treatment for the general structure area of the die-casting mold is conventional preheating;

[0023] The preheating treatment for the complex structure area of the die-casting mold is gradient preheating;

[0024] The semi-solid aluminum alloy slurry is transferred through a slurry transfer tank. A transfer pipeline is constructed between the slurry transfer tank and the pressure chamber of the die-casting mold, and the transfer pipeline is heated. After heating, the temperature of the transfer pipeline needs to ensure that the aluminum alloy slurry is in the semi-solid state;

[0025] The semi-solid aluminum alloy slurry in the slurry transfer tank is transferred through the transfer pipeline and injected into the pressure chamber of the die-casting mold after preheating treatment at a preset speed range.

[0026] Furthermore, an automated die-casting program is constructed. The process of performing full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die-casting program includes:

[0027] Construct an automated die-casting program for performing full-cycle die-casting on the semi-solid aluminum alloy slurry in the pressure chamber of the die-casting mold, construct a process database, generate several sets of die-casting parameter templates according to the alloy type to be die-cast, the casting structure, and die-casting historical data, and store the die-casting parameter templates in the process database;

[0028] The die-casting parameter templates are used to record the key die-casting parameters corresponding to each die-casting stage during the full-cycle die-casting process of the semi-solid aluminum alloy slurry; the automated die-casting program reads the process parameter library and matches the die-casting parameter template corresponding to the current semi-solid aluminum alloy slurry for full-cycle die-casting. According to the key die-casting parameters of each die-casting stage recorded in the die-casting parameter template, full-cycle die-casting control is performed on the current semi-solid aluminum alloy slurry, and then a preliminary aluminum alloy casting is formed by die-casting.

[0029] Furthermore, the process of performing solution treatment and aging heat treatment on the aluminum alloy casting after full-cycle die-casting control includes:

[0030] The solution treatment includes a heating operation process, a heat preservation operation process, and a quenching and cooling process;

[0031] Perform overburn detection and cooling uniformity verification on the aluminum alloy casting after solution treatment, and then judge whether the solution treatment meets the expectations;

[0032] If both the overburn detection and the cooling uniformity verification are successfully passed, it is judged to meet the expectations;

[0033] Otherwise, it is judged not to meet the expectations and the solution treatment is performed again;

[0034] The aging heat treatment includes temperature uniformity control and heat preservation optimization.

[0035] Furthermore, the process of supervising and intervening in the treatment processes of solution treatment and aging heat treatment to obtain the final formed aluminum alloy casting includes:

[0036] Supervise the solution treatment process and the aging heat treatment process respectively, and then determine whether there are abnormal phenomena during the solution treatment process and the aging heat treatment process;

[0037] If so, analyze the root cause of the abnormal phenomenon, and take corrective measures to intervene in the solution treatment or aging heat treatment. After the intervention is completed, the final formed aluminum alloy casting is obtained;

[0038] If not, no intervention operation is performed, and the final formed aluminum alloy casting is directly obtained.

[0039] Furthermore, an aluminum alloy semi-solid die-casting forming system, the system includes:

[0040] A semi-solid slurry preparation module, which is equipped with aluminum alloy raw materials according to a preset formula ratio, and completes the semi-solid slurry preparation process for the aluminum alloy raw materials through refinement modification treatment and dynamic staged temperature control stirring, thereby obtaining semi-solid aluminum alloy slurry;

[0041] A die-casting control module, which is used to preheat the die-casting mold, transfer and inject the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold, construct an automated die-casting program, and perform full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die-casting program;

[0042] A casting improvement die-casting module, which is used to perform solution treatment and aging heat treatment on the aluminum alloy casting after full-cycle die-casting control, and supervise and intervene in the treatment processes of the solution treatment and the aging heat treatment, thereby obtaining the final formed aluminum alloy casting.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] 1. Equip aluminum alloy raw materials according to a preset formula ratio, and complete the semi-solid slurry preparation process after refinement modification treatment and dynamic staged temperature control stirring to obtain semi-solid aluminum alloy slurry. Among them, through dynamic staged temperature control stirring, it is solved that the semi-solid aluminum alloy slurry is maintained at a better solid phase rate level, and the tissue uniformity of the semi-solid aluminum alloy slurry is enhanced.

[0045] 2. Preheat the die-casting mold, transfer and inject the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold, construct an automated die-casting program to perform full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber, and perform solution treatment and aging heat treatment after full-cycle die-casting control, and supervise and intervene in their respective treatment processes to obtain the final formed aluminum alloy casting, realizing precise and effective control of the entire process cycle of the aluminum alloy casting, improving the stability and mechanical properties of the formed aluminum alloy casting to a certain extent, and realizing high-quality die-casting of the casting. Description of the Drawings

[0046] Figure 1 This is the flowchart of the present invention. Detailed implementation manners

[0047] As Figure 1 shown, a semi-solid die casting forming method for aluminum alloy includes the following steps:

[0048] Step S1: Prepare aluminum alloy raw materials according to a preset formula ratio, and perform refinement modification treatment and dynamic stage temperature control stirring on the aluminum alloy raw materials to complete the preparation of semi-solid slurry, thereby obtaining semi-solid aluminum alloy slurry;

[0049] Step S2: Preheat the die casting mold, transfer the semi-solid aluminum alloy slurry into the pressure chamber of the die casting mold, construct an automated die casting program, and perform full-cycle die casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die casting program;

[0050] Step S3: Perform solution treatment and aging heat treatment on the aluminum alloy casting after completing full-cycle die casting control, and supervise and intervene in the treatment processes of solution treatment and aging heat treatment, thereby obtaining the final formed aluminum alloy casting.

[0051] It should be further noted that in the specific implementation process, the process of preparing aluminum alloy raw materials according to a preset formula ratio and performing refinement modification treatment and dynamic stage temperature control stirring on the aluminum alloy raw materials to obtain semi-solid aluminum alloy slurry includes:

[0052] Based on the mechanical properties of the target casting, preset the formula ratio of the aluminum alloy raw materials, prepare the aluminum alloy raw materials according to the formula ratio, and the formula components corresponding to the aluminum alloy raw materials are composed of main metal material elements and trace metal material elements;

[0053] Among them, the compositions and formula ratios of the main metal material elements and the trace metal material elements are as follows:

[0054] The main metal material elements include Al, Si, and Mg, and the formula ratio of the main metal material elements is 0.65:0.25:0.1. The trace metal material elements include Fe and Cu, and the formula ratio of the trace metal material elements is 0.6:0.4. In the aluminum alloy raw materials, the element formula ratio between the main metal material elements and the trace metal material elements is 0.85:0.15;

[0055] Select the types of refiners and modifiers;

[0056] The refinement modification treatment is specifically divided into two process steps: refinement operation and modification operation;

[0057] The aluminum alloy raw materials are refined by a refining agent. The specific content of the refining operation is as follows: determine the type of aluminum alloy to be prepared, select the corresponding different refining agents according to the type of aluminum alloy. After the refining agent is selected, add the refining agent to the aluminum alloy raw materials, and synchronously control the addition temperature, maintaining the addition temperature higher than the preset liquidus temperature;

[0058] The addition amount of the refining agent is 0.1%-0.3% of the corresponding mass of the aluminum alloy raw materials;

[0059] After the refining agent is added to the aluminum alloy raw materials, electromagnetic stirring is synchronously carried out. The rotation speed of the electromagnetic stirring is set to 200-400 rpm, and the stirring time is set to 10-20 min;

[0060] The aluminum alloy raw materials after the refining operation are modified by a modifier. The specific content of the modification operation is as follows: after determining the type of modifier, add the modifier to the aluminum alloy raw materials, and control the modification temperature of the modification operation to be higher than the eutectic temperature at which the aluminum alloy raw materials react;

[0061] Record the modification temperature as Tbz;

[0062] Record the eutectic temperature as Tgj;

[0063] Set a temperature difference control threshold and record it as Tk;

[0064] The modification temperature and the eutectic temperature need to satisfy the following relationship:

[0065] Tbz > Tgj, and Tbz - Tgj < Tk;

[0066] The modification effect of the aluminum alloy material after the modification operation is evaluated, which specifically includes: observing the morphology of eutectic silicon by metallographic analysis, comparing the elongation before and after modification through mechanical property testing, and obtaining the cooling curve of the aluminum alloy material through a thermal analyzer;

[0067] When the spheroidization rate of eutectic silicon is greater than 80%, the elongation increases by more than 30%, and the cooling effect is within the expected range through the analysis of the cooling curve, the modification operation is successfully completed, and dynamic stage temperature control stirring is continued.

[0068] It should be noted that ensuring that the addition temperature of the refining agent is higher than the liquidus temperature is to ensure the full dissolution and dispersion of the refining agent. The electromagnetic stirring carried out to a certain extent avoids the sedimentation of the refining agent; ensuring that the modification temperature is slightly higher than the eutectic temperature effectively avoids the oxidation and burning loss of the modifier. It should be noted that the modification operation needs to be carried out after all the refining operations are completed, and the purpose is to prevent the reaction between the modifying elements and the refining agent.

[0069] The content of dynamic stage temperature control stirring is as follows:

[0070] The aluminum alloy slurry after refinement and modification is stirred by means of electromagnetic stirring + mechanical stirring. According to the stage of the aluminum alloy slurry, the stirring temperature and stirring parameters are dynamically changed. Among them, when the aluminum alloy slurry is above the liquidus line, it corresponds to the pure liquid stage. The stirring temperature is uniformly decreased from the initial temperature value until the aluminum alloy slurry is gradually cooled to the semi-solid stage. Record the real-time temperature of the aluminum alloy slurry in the semi-solid stage and maintain this real-time temperature;

[0071] Simultaneously measure the solid-liquid ratio of the aluminum alloy slurry in the semi-solid stage to obtain the corresponding solid fraction;

[0072] Record the solid fraction as G-score;

[0073] G-score = mass of the solid part in the aluminum alloy slurry / total mass of the aluminum alloy slurry;

[0074] Set the solid-phase compliance fraction and record it as Db-Score;

[0075] When G-score ≥ Db-Score, the dynamic staged temperature control stirring is completed, and the preparation process of the semi-solid slurry is completed to obtain the final semi-solid aluminum alloy slurry;

[0076] When G-score < Db-Score, set the temperature control range. Within the temperature control range, adjust the real-time temperature of the stirring environment where the aluminum alloy slurry is located by increasing or decreasing it at a fixed value, and stir the aluminum alloy slurry to obtain the real-time solid fraction of the aluminum alloy slurry until the solid fraction meets the expectation. Then stop stirring and temperature adjustment to obtain the final semi-solid aluminum alloy slurry.

[0077] Construct the temperature matching curves of the aluminum alloy slurry in the pure liquid stage and the semi-solid stage under ideal conditions respectively;

[0078] Divide the quality monitoring points of the aluminum alloy slurry in the pure liquid stage and the semi-solid stage respectively;

[0079] The pure liquid stage and the semi-solid stage are collectively referred to as the state stages of the aluminum alloy slurry;

[0080] Judge whether the point temperatures of the dynamic staged temperature control stirring at the respective quality monitoring points of the aluminum alloy slurry in different state stages can match the temperature matching curves. If so, do not perform any operation. If not, adjust the temperature of the aluminum alloy slurry at the corresponding quality monitoring point so that its stirring temperature matches the curve temperature corresponding to the temperature matching curve at the quality monitoring point;

[0081] By judging whether the point temperature at the quality monitoring point matches the temperature matching curve and timely adjusting the temperature when they do not match, the formation of dendrites during the stirring process of the aluminum alloy slurry is avoided, and the uniformity of the slurry is ensured to a certain extent.

[0082] It should be further noted that in the specific implementation process, the preheating treatment of the die-casting mold and the process of transferring and injecting the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold include:

[0083] Three-dimensional modeling of the die-casting mold is carried out through computer vision technology, and then a three-dimensional solid structure model corresponding to the die-casting mold is constructed. The complexity of each mold area of the die-casting mold represented by the three-dimensional solid structure model is evaluated through computer graphics technology, and then the die-casting mold is divided into a complex structure area and a general structure area;

[0084] The preheating treatment for the general structure area of the die-casting mold is conventional preheating, and the content of the conventional preheating is: directly preheating the general structure area with a heating furnace and maintaining the area temperature of the general structure area within the melting point range of the semi-solid aluminum alloy slurry;

[0085] The preheating treatment for the complex structure area of the die-casting mold is gradient preheating, and the content of the gradient preheating is: dividing the complex structure area into a cavity surface in direct contact with the high-temperature slurry, a runner for transferring the high-temperature slurry, and a mold back surface not in contact with the high-temperature slurry according to the functions corresponding to the injection of the semi-solid aluminum alloy slurry into it;

[0086] The cavity surface is preheated with a first gradient temperature, and the first gradient temperature is set to 250 - 300 °C. The purpose is to ensure that it is in the same temperature range as the semi-solid aluminum alloy slurry and prevent the slurry from solidifying;

[0087] The runner is preheated with a second gradient temperature, and the second gradient temperature is set to 200 - 250 °C. The purpose is to slow down the solidification rate of the semi-solid aluminum alloy slurry;

[0088] The mold back surface is preheated with a third gradient temperature, and the third gradient temperature is set to 150 - 200 °C. The purpose is to balance the overall thermal expansion and reduce deformation;

[0089] The semi-solid aluminum alloy slurry is transferred through a slurry transfer tank. A transfer pipeline is constructed between the slurry transfer tank and the pressure chamber of the die-casting mold, and the transfer pipeline is heated synchronously. After heating, the temperature of the transfer pipeline needs to ensure that the aluminum alloy slurry is in the semi-solid state;

[0090] The semi-solid aluminum alloy slurry in the slurry transfer tank is transferred and injected into the pressure chamber of the preheated die-casting mold through the transfer pipeline within a preset speed range.

[0091] It should be noted that the purpose of preheating the die-casting mold is to ensure that the mold maintains a certain temperature, prevent the semi-solid aluminum alloy slurry from solidifying rapidly due to the too low temperature of the mold during injection, and affect the quality of subsequent castings and the service life of the mold; at the same time, heat the slurry transfer tank and transfer pipeline, and transfer and inject the semi-solid aluminum alloy slurry into the aluminum alloy mold according to the speed range, aiming to prevent the semi-solid aluminum alloy slurry from solidifying during the transfer process. Among them, when transferring the semi-solid aluminum alloy slurry in the transfer pipeline, ensuring it within the speed range prevents defects such as pores or inclusions caused by too fast injection speed of the slurry, and also prevents premature solidification of the slurry caused by too slow injection speed of the slurry.

[0092] It should be further noted that in the specific implementation process, the process of constructing an automated die-casting program and performing full-cycle die-casting control on the semi-solid aluminum alloy slurry in the shot chamber through the automated die-casting program includes:

[0093] Construct an automated die-casting program for full-cycle die-casting of the semi-solid aluminum alloy slurry in the shot chamber corresponding to the die-casting mold, construct a process database, generate several sets of die-casting parameter templates according to the alloy type to be die-cast, the casting structure, and the die-casting historical data, and store the die-casting parameter templates in the process database;

[0094] The die-casting parameter template is used to record the key die-casting parameters corresponding to each die-casting stage of the semi-solid aluminum alloy slurry during the full-cycle die-casting process; the automated die-casting program reads the process parameter library and matches the die-casting parameter template corresponding to the current semi-solid aluminum alloy slurry for full-cycle die-casting from it, and then performs full-cycle die-casting control on the current semi-solid aluminum alloy slurry according to the key die-casting parameters of each die-casting stage recorded in the die-casting parameter template;

[0095] The die-casting stages include a slow filling stage, a high-speed boosting stage, a pressure holding stage, and a cooling and mold opening stage;

[0096] In the slow filling stage, the automated die-casting program controls the pre-configured punch to advance at a constant filling speed, and then performs die-casting filling on the semi-solid aluminum alloy slurry in the shot chamber, and real-time monitors the front-end pressure of the shot chamber corresponding to the die-casting mold, and regulates and maintains the front-end pressure below the preset target pressure;

[0097] Set the monitoring frequency and monitor the change amplitude of the front-end pressure in real time according to the monitoring frequency;

[0098] If the change amplitude exceeds the preset amplitude upper limit, it means that the pressure surges when the punch advances the semi-solid slurry, and it is determined that the semi-solid aluminum alloy slurry solidifies in advance, and synchronously triggers the boosting operation emergently, otherwise, no operation is performed;

[0099] It should be noted that the purpose of the slow filling stage is to stably fill the runner and cavity in the pressure chamber, avoid air entrainment or slurry splashing. The constant filling speed of the punch is jointly determined by the diameter of the pressure chamber and the slurry viscosity. Denote the constant filling speed as v, and the calculation formula for the constant filling speed is as follows:

[0100] v = Q / (A × ρ);

[0101] Wherein, Q is the slurry flow rate, A is the cross-sectional area of the pressure chamber, and ρ is the slurry density.

[0102] In the high-speed boosting stage, two-stage boosting is adopted. First, the punch is advanced at the first boosting speed to break through the front resistance of the slurry in the pressure chamber. After breakthrough, the punch is then switched to the second boosting speed to complete the filling of the semi-solid aluminum alloy slurry in the pressure chamber;

[0103] Among them, the first boosting speed is less than the second boosting speed;

[0104] A pressure sensor is deployed inside the cavity of the pressure chamber to monitor the cavity pressure in real time. When the cavity pressure reaches the preset end pressure value, the advancement of the punch in the pressure chamber for the semi-solid aluminum alloy slurry is synchronously stopped, and the preliminary aluminum alloy casting is die-cast;

[0105] In the pressure holding stage, pressure holding operations are performed on the die-casting mold and the aluminum alloy casting in the corresponding pressure chamber of the die-casting mold;

[0106] Set the initial pressure holding pressure, and the initial pressure holding pressure is set to 80%-90% of the boosting pressure corresponding to the second boosting speed in the high-speed boosting stage;

[0107] Adopt a stepped pressure reduction method to uniformly reduce the pressure holding pressure, thereby relieving the mold stress. For example, reduce the pressure holding pressure by 5% every 1 second;

[0108] The calculation formula for the pressure holding time corresponding to the pressure holding operation is as follows:

[0109] Pressure holding time = maximum wall thickness of the casting 2 / (4 × thermal diffusivity);

[0110] For example: For A356 aluminum alloy, the thermal diffusivity α = 8.5×10 -5 m 2 / s, the maximum wall thickness of the casting corresponding to A356 aluminum alloy is 5 mm, then the calculated pressure holding time is 7.4 s;

[0111] In the cooling and mold opening stage, inject cooling water into the die-casting mold, control the real-time flow rate of the cooling water through PID, and keep the mold temperature of the die-casting mold within the error range of the set ideal temperature value, such as an error range of ±10°C, and use high-pressure water needles to spray and cool the local thick and large areas of the die-casting mold;

[0112] Determine whether the aluminum alloy casting in the die-casting mold meets the mold-opening condition;

[0113] Monitor the surface temperature of the aluminum alloy casting through an infrared temperature measurement device. If the surface temperature drops within the preset mold-opening temperature range, it is determined that the mold-opening condition is met, and the aluminum alloy casting in the die-casting mold is demolded. Otherwise, no operation is performed.

[0114] It should be further noted that in the specific implementation process, the process of solution treatment and aging heat treatment for the aluminum alloy casting after completing the full-cycle die-casting control includes:

[0115] The solution treatment includes a heating operation process, a heat preservation operation process, and a quenching and cooling process;

[0116] Execute the heating operation process, set the corresponding heating temperature according to the type of the aluminum alloy casting, and monitor the temperature fluctuation in real time, keeping the temperature fluctuation within ±5°C to avoid overburning or insufficient dissolution of the aluminum alloy casting. Among them, the aluminum alloy casting is divided into a thin-wall area and a thick-wall area;

[0117] Set the heating rate of the corresponding heating temperature in the thin-wall area to the first rate;

[0118] The set range of the first rate is: [6, 10], unit: °C / min;

[0119] Set the heating rate of the corresponding heating temperature in the thick-wall area to the second rate;

[0120] The set range of the second rate is: [3, 5], unit: °C / min;

[0121] Execute the heat preservation operation process, calculate the heat preservation time according to the empirical formula, and the heat preservation time is calculated as follows:

[0122] Heat preservation time (h) = 1.5 × maximum wall thickness of the aluminum alloy casting (mm) / 10;

[0123] For example: the heat preservation time of an A356 aluminum alloy casting with a wall thickness of 10 mm is 1.5 hours;

[0124] Under the heat preservation time, protect the aluminum alloy casting with an inert gas and add a surface covering agent on the surface of the aluminum alloy casting to prevent the aluminum alloy casting from oxidizing;

[0125] Execute the quenching and cooling process, select a matching cooling medium according to the type of the aluminum alloy casting, set the cooling rate of the cooling medium used, set the transfer time for the aluminum alloy casting to be transferred to the quenching tank, and keep the transfer time less than or equal to the preset critical transfer duration;

[0126] Perform overburn detection and cooling uniformity verification on the solution-treated aluminum alloy castings, and then determine whether the solution treatment meets the expectations;

[0127] If both the overburn detection and the cooling uniformity verification are successfully passed, it is judged to meet the expectations;

[0128] Otherwise, it is judged not to meet the expectations and the solution treatment is carried out again;

[0129] Among them, metallographic observation and hardness test are used as means for overburn detection. Metallographic observation: If remelting balls appear at the grain boundaries of the aluminum alloy casting, it is judged as overburn; Hardness test: If the hardness of the aluminum alloy casting drops abnormally, it is judged that the aluminum alloy has overburn; For example, the hardness of A356 aluminum alloy casting after normal quenching is 80HB, but the hardness after overburn will drop to 60HB and below;

[0130] Monitor the surface temperature distribution of the aluminum alloy casting through an infrared thermal imager, and then carry out cooling uniformity verification. If the temperature difference of the surface temperature distribution is greater than or equal to the preset upper limit of the temperature difference, it is judged that the cooling uniformity verification of the current aluminum alloy casting fails; otherwise, it is judged that the verification is passed;

[0131] The aging heat treatment includes temperature uniformity control and holding optimization;

[0132] Construct the aging furnace temperature field and maintain the uniformity of the aging furnace temperature field ≤ ±3°C;

[0133] The maintenance of the temperature uniformity of the aging furnace temperature field is carried out through convection fans and multi-point thermocouple calibration, and the heating rate of the aging furnace temperature field is controlled to avoid the coarsening of the precipitation phase of the aluminum alloy casting caused by temperature shock;

[0134] Construct an optimization equation for temperature optimization. The expression of the optimization equation is as follows:

[0135]

[0136] Among them, t is the final required duration for temperature optimization, t0 is the set time, Q is the activation energy, R is the gas constant, T 实际 is the actual temperature, T 设定 is the set temperature;

[0137] Monitor and adjust the real-time casting temperature through the optimization equation, and then complete the temperature optimization of the aluminum alloy casting.

[0138] It should be further noted that in the specific implementation process, the process of supervising and intervening in the solution treatment and the aging heat treatment process to obtain the final aluminum alloy casting formed part includes:

[0139] Supervise the solution treatment process and the aging heat treatment process respectively, and then determine whether there are any abnormal phenomena during the solution treatment and the aging heat treatment processes;

[0140] If so, analyze the root cause of the abnormal phenomenon, and take corrective measures to intervene in the solution treatment or the aging heat treatment. After the intervention is completed, the final formed aluminum alloy casting is obtained;

[0141] If not, no intervention operation is performed, and the final formed aluminum alloy casting is directly obtained.

[0142] Construct a supervision and intervention chain. The form of the supervision and intervention chain is: abnormal phenomenon -> root cause -> corrective measure. The following are examples:

[0143] When the abnormal phenomenon is that the hardness of the aluminum alloy casting after solution treatment is insufficient, the corresponding root cause of the abnormal phenomenon is insufficient holding time or low temperature, and the corresponding corrective measure is: re-solution treatment, extending the holding time by 10%-20%;

[0144] When the abnormal phenomenon is that the strength is too low after aging heat treatment, the corresponding root cause of the abnormal phenomenon is over-aging caused by too high aging temperature, and the corresponding corrective measure is: adjusting the temperature to the lower limit and shortening the time;

[0145] When the abnormal phenomenon is that the aluminum alloy casting is deformed and cracked, the corresponding root cause of the abnormal phenomenon is uneven quenching cooling rate or contaminated cooling medium, and the corresponding corrective measure is: optimizing the quenching tank stirring system and replacing the cooling medium;

[0146] When the abnormal phenomenon is that the surface oxidation of the aluminum alloy casting is serious, the corresponding root cause of the abnormal phenomenon is too high oxygen content in the furnace or the covering agent fails. At this time, the corresponding corrective measure is: filling high-purity nitrogen and updating the covering agent.

[0147] The present invention also provides an aluminum alloy semi-solid die casting forming system, which includes:

[0148] A semi-solid slurry preparation module, which prepares aluminum alloy raw materials according to a preset formula ratio, and completes the semi-solid slurry preparation process for the aluminum alloy raw materials through refinement modification treatment and dynamic staged temperature control stirring, and then obtains semi-solid aluminum alloy slurry;

[0149] A die casting control module, which is used to preheat the die casting mold, transfer and inject the semi-solid aluminum alloy slurry into the pressure chamber of the die casting mold, construct an automatic die casting program, and perform full-cycle die casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automatic die casting program;

[0150] The casting improvement die-casting module is used for solution treatment and aging heat treatment of aluminum alloy castings after completing the full-cycle die-casting control, and supervising and intervening in the treatment processes of the solution treatment and the aging heat treatment, so as to obtain the final formed aluminum alloy casting.

[0151] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical method of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A semi-solid die casting forming method for aluminum alloy, characterized in that, It includes the following steps: Step S1: Prepare aluminum alloy raw materials according to a preset formula ratio, and perform refining modification treatment and dynamic stage temperature control stirring on the aluminum alloy raw materials to complete the preparation of semi-solid slurry, thereby obtaining semi-solid aluminum alloy slurry; Step S2: Preheat the die-casting mold, transfer the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold, construct an automated die-casting program, and perform full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die-casting program; Step S3: Perform solution treatment and aging heat treatment on the aluminum alloy casting after completing the full-cycle die-casting control, and supervise and intervene in the treatment process of the solution treatment and aging heat treatment, thereby obtaining the final formed aluminum alloy casting.

2. The semi-solid die casting forming method of an aluminum alloy according to claim 1, characterized in that The process of preparing semi-solid aluminum alloy slurry by preparing aluminum alloy raw materials according to a preset formula ratio and performing refining modification treatment and dynamic stage temperature control stirring on the aluminum alloy raw materials includes: Based on the mechanical properties of the target casting, prepare aluminum alloy raw materials according to the preset formula ratio; Select the types of refining agents and modification agents; The refining modification treatment is specifically divided into a refining operation and a modification operation; Perform a refining operation on the aluminum alloy raw materials with a refining agent; Perform a modification operation on the aluminum alloy raw materials after the refining operation with a modification agent; Evaluate the modification effect of the aluminum alloy material after the modification operation. When the modification operation is successfully completed, continue to perform dynamic stage temperature control stirring to obtain the final semi-solid aluminum alloy slurry.

3. A semi-solid die-casting forming method for aluminum alloy according to claim 2, characterized in that, The process of the dynamic stage temperature control stirring includes: Stir the aluminum alloy slurry after refining modification by using electromagnetic stirring + mechanical stirring, dynamically change the stirring temperature and stirring parameters according to the stage of the aluminum alloy slurry. Among them, the stage of the aluminum alloy slurry includes the pure liquid stage and the semi-solid stage. Record the real-time temperature of the aluminum alloy slurry in the semi-solid stage and maintain this real-time temperature. Synchronously measure the solid-liquid ratio of the aluminum alloy slurry in the semi-solid stage to obtain the corresponding solid phase fraction, and record it as G-score; Set the solid phase compliance fraction and record it as Db-Score; When G-score≥Db-Score, the dynamic stage temperature control stirring is completed; When G-score<Db-Score, set the temperature control range, increase or decrease the real-time temperature of the stirring environment where the aluminum alloy slurry is located at a fixed value within the temperature control range, and stir the aluminum alloy slurry to obtain the real-time solid phase fraction of the aluminum alloy slurry until the solid phase fraction meets the expectation, then stop stirring and temperature adjustment.

4. A semi-solid die casting forming method for aluminum alloy according to claim 3, characterized in that The process of preheating the die-casting mold and transferring the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold includes: Perform three-dimensional modeling on the die-casting mold to construct a corresponding three-dimensional solid structure model, and divide the die-casting mold into a complex structure area and a general structure area; The preheating treatment for the general structure area of the die-casting mold is conventional preheating; The preheating treatment for the complex structure area of the die-casting mold is gradient preheating; The semi-solid aluminum alloy slurry is transferred through a slurry transfer tank. A transfer pipeline is constructed between the slurry transfer tank and the pressure chamber of the die-casting mold, and the transfer pipeline is heated. After heating, the temperature of the transfer pipeline needs to ensure that the aluminum alloy slurry is in the semi-solid state; The semi-solid aluminum alloy slurry in the slurry transfer tank is transferred and injected into the pressure chamber of the die-casting mold that has completed preheating treatment through the transfer pipeline at a preset speed range.

5. A semi-solid die casting forming method for aluminum alloy according to claim 4, characterized in that, An automated die-casting program is constructed. The process of performing full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die-casting program includes: Construct an automated die-casting program for performing full-cycle die-casting on the semi-solid aluminum alloy slurry in the pressure chamber of the die-casting mold, construct a process database, generate several sets of die-casting parameter templates according to the alloy type to be die-cast, the casting structure, and die-casting historical data, and store the die-casting parameter templates in the process database; The die-casting parameter template is used to record the key die-casting parameters corresponding to each die-casting stage during the full-cycle die-casting process of the semi-solid aluminum alloy slurry; the automated die-casting program reads the process parameter library and matches the die-casting parameter template corresponding to the current semi-solid aluminum alloy slurry for full-cycle die-casting. According to the key die-casting parameters of each die-casting stage recorded in the die-casting parameter template, full-cycle die-casting control is performed on the current semi-solid aluminum alloy slurry, and then a preliminary aluminum alloy casting is formed by die-casting.

6. A semi-solid die casting forming method for aluminum alloy according to claim 5, characterized in that The process of performing solution treatment and aging heat treatment on the aluminum alloy casting after completing full-cycle die-casting control includes: The solution treatment includes a heating operation process, a heat preservation operation process, and a quenching and cooling process; Perform overburn detection and cooling uniformity verification on the aluminum alloy casting after solution treatment, and then judge whether the solution treatment meets the expectations; If both the overburn detection and the cooling uniformity verification are successfully passed, it is judged to meet the expectations; Otherwise, it is judged not to meet the expectations, and the solution treatment is performed again; The aging heat treatment includes temperature uniformity control and heat preservation optimization.

7. A semi-solid die casting forming method for aluminum alloy according to claim 6, characterized in that The process of supervising and intervening in the treatment processes of solution treatment and aging heat treatment to obtain the final formed aluminum alloy casting includes: Supervise the treatment processes of solution treatment and aging heat treatment respectively, and then judge whether there are abnormal phenomena in the treatment processes of solution treatment and aging heat treatment; If so, analyze the root cause of the abnormal phenomenon and take corrective measures to intervene in the solution treatment or aging heat treatment. After the intervention is completed, the final formed aluminum alloy casting is obtained; If not, no intervention operation is performed, and the final formed aluminum alloy casting is directly obtained.

8. An aluminum alloy semi-solid die casting forming system for implementing the aluminum alloy semi-solid die casting forming method according to any one of claims 1 to 7, characterized in that, The system includes: A semi-solid slurry preparation module that prepares aluminum alloy raw materials according to a preset formula ratio, and completes the semi-solid slurry preparation process for the aluminum alloy raw materials through refinement modification treatment and dynamic stage temperature control stirring, and then obtains semi-solid aluminum alloy slurry; A die-casting control module that preheats the die-casting mold, transfers and injects the semi-solid aluminum alloy slurry into the pressure chamber of the die-casting mold, constructs an automated die-casting program, and performs full-cycle die-casting control on the semi-solid aluminum alloy slurry in the pressure chamber through the automated die-casting program; The casting improvement die-casting module is used to perform solution treatment and aging heat treatment on aluminum alloy castings after completing the full-cycle die-casting control, and to supervise and intervene in the treatment processes of solution treatment and aging heat treatment, so as to obtain the final formed aluminum alloy casting.

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