A semi-solid magnesium alloy rheocontinuous casting injection molding device and method

Abstract

The application relates to the technical field of semi-solid forming, in particular to a semi-solid magnesium alloy rheological continuous casting and injection forming device and method, which comprises a rheological control cavity provided with a material inlet and a slurry outlet, the material inlet is used for being connected to a container containing semi-solid magnesium alloy slurry, a double-screw structure is arranged in the rheological control cavity, and the double-screw structure and a machine body form a rheological shearing cavity, one end of the rheological shearing cavity is communicated with the material inlet, and the outer wall of the rheological control cavity is further provided with an infrared heating component and a first temperature monitoring component. The application provides a short-process continuous manufacturing path integrating slurry, pressure, nucleation and forming, under the premise of reducing the dependence on subsequent plastic deformation for refining grains, magnesium alloy rods with a high solid phase rate, equiaxed spherical fine crystal organization and a low segregation degree can be continuously crystallized from semi-solid slurry.

Description

Technical Field

[0001] This invention relates to the field of metal casting and semi-solid metallurgical processing technology, and more specifically to a semi-solid magnesium alloy rheological continuous casting injection molding apparatus and method. Background Technology

[0002] The manufacture of high-performance magnesium alloy structural components relies on extruded bars with a high compression ratio and an ultra-fine, uniform equiaxed grain structure. However, the traditional approach to obtaining such bars in industrial practice presents an inherent contradiction: to obtain large-sized extruded billets, a casting solidification process is necessary; but this process introduces difficult-to-eradicate dendritic structures, macroscopic segregation, and microscopic defects into the material. These defects must then be eliminated through large plastic deformation during subsequent hot extrusion. This circuitous path of first creating defects and then eliminating them inherently determines the high energy consumption and performance limitations of this technological approach.

[0003] To overcome this predicament, semi-solid rheoforming technology offers a new approach. The core of this technology lies in modulating the alloy melt in the solid-liquid two-phase region using an external force field, directly obtaining a semi-solid slurry with a primary phase exhibiting near-spherical particle morphology and uniformly suspended in the liquid phase, which is then directly shaped. Compared to traditional deep-well casting, the semi-solid slurry preparation process skips the crucial step of ingot solidification, which forms dendritic structures and internal defects, thus avoiding the generation of material genetic defects at the source. Therefore, it is considered an ideal technological path for achieving short-process manufacturing of high-performance magnesium alloys.

[0004] For example, the system and process for direct pulping and forming without the need for semi-solid slurry transfer proposed in publication number CN111001779A firstly prepares a semi-solid slurry with a predetermined solid fraction through an independent pulping device, then transfers the slurry to a forming device, and uses a punch to push the slurry into the mold cavity with a certain pressure and speed. After cooling and solidification, the formed workpiece is obtained.

[0005] However, applying the aforementioned semi-solid rheoforming technology based on punch injection to prepare magnesium alloy rods with a high compression ratio (10:1) faces a series of engineering challenges.

[0006] To achieve the high deformation and sufficient densification required for high compression ratio extruded bars, the slurry needs to undergo a flow process with a significant reduction in cross-sectional area at the forming end. Semi-solid slurries with a solids content of up to 60% exhibit extremely high apparent viscosity and significant real-world fluid characteristics, with flow resistance far exceeding that of liquid metal. The filling pressure provided by the punch injection method is limited by the size of the injection cylinder and the power system, resulting in insufficient pressure build-up and a significant decrease in slurry filling speed when propelling high-solids slurry through high-compression-ratio channels. Furthermore, the flow behavior of high-solids slurry in the region of rapid channel cross-section contraction is extremely complex, easily leading to asynchronous flow of the solid and liquid phases. That is, the liquid phase flows preferentially under pressure, while solid particles remain or accumulate near the channel wall, resulting in incomplete filling or uneven microstructure.

[0007] Under high compression ratio forming conditions, the slurry undergoes intense shearing as it flows through the cross-sectional shrinkage region. This strong shearing, while refining the grains and improving the microstructure, also generates significant frictional heat due to viscous dissipation, leading to localized temperature increases in the slurry. This can cause some solid particles to remelt, resulting in uncontrolled changes in the solid fraction. The decrease in solid fraction weakens the thixotropic properties of the semi-solid slurry, exacerbating the tendency for solid-liquid separation and creating a vicious cycle of shearing → temperature rise → remelting → segregation. Existing punch injection forming processes typically lack mechanisms for real-time control of slurry temperature and solid fraction during the forming process. Summary of the Invention

[0008] To address the technical problems existing in the prior art, the first aspect of the present invention proposes a technical solution: a semi-solid magnesium alloy rheological continuous casting injection molding apparatus, comprising: The rheological control chamber has a material inlet for connecting to a semi-solid magnesium alloy slurry container and a slurry outlet. Inside, there is a twin-screw structure that forms a rheological shearing chamber with the machine body, which is used to shear and break up the semi-solid magnesium alloy slurry to suppress dendrite growth. The outer wall of the rheological control chamber is equipped with an infrared heating component and a first temperature monitoring component. It is also equipped with a driver to drive the twin-screw structure. A torque detection component is provided between the driver and the twin-screw structure. A flow valve, connected to the material inlet, is used to control the flow rate of the semi-solid slurry entering the rheological shear chamber; A rheological filling crystallization mold is connected to the slurry outlet; The controller is electrically connected to the driver, torque detection component, infrared heating component, first temperature monitoring component, and flow valve; The controller is configured to: maintain the twin-screw structure rotating at the target speed; use the real-time torque N collected by the torque detection component as the criterion for the apparent viscosity and phase change load of the semi-solid slurry; cascade control the opening of the flow valve and the radiation power of the infrared heating component to compensate for the temperature control lag caused by the latent heat of phase change and frictional shear heat; control the real-time temperature collected by the first temperature monitoring component within the preset semi-solid target temperature range; and continuously press the slurry into the rheological filling crystallization mold to continuously solidify and form fine-grained magnesium alloy rods.

[0009] Preferably, the rheological control chamber is divided into a suction section, a high-shear section, and a homogenization discharge section from the material inlet to the slurry outlet. The twin-screw structure is configured such that the pitch in the suction section is L1, the pitch in the high-shear section is L2, and the pitch in the homogenization discharge section is L3, where L1>L2>L3.

[0010] Preferably, the infrared heating component includes infrared heating coils arranged around the periphery of the rheological shearing chamber, wherein infrared heating coils are arranged at a first spacing P1 in the material suction section, infrared heating coils are arranged at a second spacing P2 in the high shear section, and infrared heating coils are arranged at a third spacing P3 in the homogenization discharge section, and the installation spacing of the infrared heating coils satisfies P2> P1> P3.

[0011] Preferably, the first temperature monitoring component includes a first thermocouple, a second thermocouple, and a third thermocouple embedded in the pipe walls of the suction section, the high-shear section, and the homogenization discharge section, respectively, for independently acquiring the corresponding real-time temperatures T1, T2, and T3.

[0012] Preferably, it further includes: a second temperature monitoring component for monitoring the current furnace temperature T of the semi-solid magnesium alloy slurry inside the container. 炉 ; A liquid level monitoring component is used to monitor the real-time liquid level H of the semi-solid magnesium alloy slurry inside the container; The second temperature monitoring component and the liquid level monitoring component are electrically connected to the controller, which is configured to: Obtain the furnace temperature T measured by the second temperature monitoring component. 炉 The flow valve is unlocked to allow material feeding only when the furnace temperature reaches the preset semi-solid temperature zone. The liquid level H measured by the liquid level monitoring component is obtained, and the opening of the flow valve is adjusted in the opposite direction according to the change of the liquid level H to compensate for static pressure fluctuations.

[0013] Preferably, the controller is further configured to: Based on the real-time torque N collected by the torque detection component and the real-time temperature collected by the first temperature monitoring component, flow field-thermal field coordinated control is performed, the coordinated control including: When the real-time temperature T2 in the high-shear section exceeds the first preset upper temperature threshold and the real-time torque N is lower than the preset lower torque threshold, the heating power of the infrared heating component corresponding to the high-shear section region is reduced or turned off. When the real-time temperature T3 in the homogenization discharge section is lower than the second preset lower limit threshold and the real-time torque N exceeds the first preset upper limit threshold, thermal compensation and flow regulation are performed.

[0014] Preferably, the controller's thermal compensation and flow regulation adopt a two-tiered, step-by-step coordinated rule: First-stage control: Within a set response time, the radiation power of the infrared heating component corresponding to the homogenization discharge section area is increased according to a first preset ratio, while keeping the current opening of the flow valve unchanged; Second-stage control: If the real-time torque N continues to rise and exceeds the second preset torque upper limit threshold after the first-stage control is executed, the flow valve is controlled to reduce the opening by a preset ratio to implement flow throttling and load reduction.

[0015] Preferably, the rheological filling crystallization mold has a progressively variable cross-section rheological crystallization cavity inside. The rheological crystallization cavity has a rheological shear structure for applying three-dimensional shear stress to the semi-solid magnesium alloy slurry passing through. The rheological shear structure includes a flow divider cone disposed inside the rheological crystallization cavity and rheological shear microtexture protrusions arranged in a herringbone pattern on the inner sidewall of the rheological crystallization cavity.

[0016] The second aspect of this invention provides a technical solution: a semi-solid magnesium alloy rheological continuous casting injection molding method, employing the aforementioned semi-solid magnesium alloy rheological continuous casting injection molding apparatus, comprising the following steps: Step S1: Control the flow valve through the controller to feed the temperature-controlled semi-solid magnesium alloy slurry into the rheological control chamber at a constant flow rate; Step S2: The variable pitch twin-screw structure of the rheological control cavity shears and conveys the slurry. The controller cascades and adjusts the opening of the flow valve and the power of the infrared heating component based on the real-time torque N of the torque detection component and the real-time temperature of the first temperature monitoring component. Step S3: The slurry processed in step S2 is continuously pressed into the rheological filling and crystallization mold. The rheological shear structure applies three-dimensional shear stress to the slurry, causing it to undergo in-situ secondary nucleation, and high solids magnesium alloy rods are continuously cast.

[0017] Preferably, in step S2, the cascaded control includes: When the real-time temperature T2 of the high-shear section exceeds the first preset upper temperature threshold and the real-time torque N is lower than the preset lower torque threshold, the heating power of the corresponding area is reduced or turned off; when the real-time temperature T3 of the homogenization discharge section is lower than the second preset lower temperature threshold and the real-time torque N exceeds the first preset upper torque threshold, the first step control is executed sequentially to perform external heat flow compensation and the second step control is executed to reduce the feeding amount.

[0018] Compared with the prior art, the advantages of the present invention are as follows: This invention provides a short-process continuous manufacturing path that integrates slurry, pressure, nucleation, and forming. It can directly and continuously extrude magnesium alloy rods with high solid fraction, equiaxed spherical fine grain structure, and low segregation from semi-solid slurry while reducing dependence on subsequent plastic deformation to refine grains.

[0019] This invention reads the furnace temperature and liquid level in the upstream container through a controller, executes the physical state disconnection safety interlock and static pressure self-compensation rules, and only unlocks the feeding when the slurry reaches the preset semi-solid temperature zone. This can reduce the risk of equipment damage or product scrap caused by unqualified materials entering the rheological control chamber. At the same time, by monitoring the changes in slurry liquid level in real time and adjusting the opening of the flow valve in reverse linearly, it compensates for the feed amount drift caused by static pressure fluctuations, providing more stable feeding conditions for subsequent rheological control.

[0020] This invention uses the real-time torque of the twin-screw structure as a direct criterion for characterizing the rheological state of the slurry, and performs cascaded judgment with the segmented temperature. When the risk of overcooling and crusting is detected in the homogenization discharge section, the infrared radiation power is increased first to dissolve the crusting on the wall without changing the feed rate. Only when thermal compensation is ineffective, the feed rate is reduced to protect the equipment. At the same time, in response to the risk of overheating and remelting caused by mechanical friction in the high-shear section, the external heating can be actively cut off and heat dissipation can be achieved by relying on natural convection, thereby assisting in the control of the slurry solids ratio while ensuring the continuity of the process.

[0021] This invention utilizes the high extrusion pressure and stable solid fraction provided by the rheological control cavity to provide a material source with stable pressure, uniform temperature, and controllable rheological properties for the rheological filling and crystallization mold. Through the progressive variable cross-section flow channel and rheological shear structure of the rheological filling and crystallization mold, the solid fraction is increased, which helps to improve the solid fraction and continuously extrude equiaxed spherical fine-grained magnesium alloy rods while reducing the genetic dependence on the traditional ingot structure. Attached Figure Description

[0022] The accompanying drawings are not strictly to scale. In the drawings, each identical or nearly identical component shown in the various figures can be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the overall structure of the semi-solid magnesium alloy rheological continuous casting injection molding device shown in this invention. Figure 2 This is a schematic diagram of the electrical connection of the controller shown in this invention; Figure 3 This is the control principle diagram shown in this invention; Figure 4 This is a schematic diagram of the structure of the rheological filling crystallization mold shown in this invention; Explanation of reference numerals in the attached figures: 100. Rheological control chamber; 101. Suction section; 102. High shear section; 103. Homogenization discharge section; 110. Driver; 111. Torque detection component; 120. Infrared heating component; 130. First temperature monitoring component; 200. Flow valve; 210. Second temperature monitoring component; 220. Liquid level monitoring component; 300. Rheological filling crystallization mold; 301. Inlet end; 302. Outlet end; 303. Rheological crystallization cavity; 400. Controller; 500. Fine-grained magnesium alloy rod. Detailed Implementation

[0023] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0024] {Example 1} Combination Figure 1 As shown, the first aspect of the present invention proposes a technical solution: a semi-solid magnesium alloy rheological continuous casting injection molding device, comprising a rheological control chamber 100, a flow valve 200, a rheological filling crystallization mold 300, a second temperature monitoring component 210, a liquid level monitoring component 220, and a controller 400.

[0025] The flow valve 200 is installed between the bottom outlet of the upstream container (rheology modulator) containing the semi-solid magnesium alloy slurry and the material inlet of the downstream rheology control chamber 100. It is used to control the flow rate of the semi-solid magnesium alloy slurry entering the rheology shear chamber of the rheology control chamber 100.

[0026] Optionally, the valve employs a high-temperature resistant, magnesium molten metal-resistant, high-sealing, hard-seal fluid proportioning control spool valve mechanism. Its actuator is controlled by the analog current signal output from the controller 400.

[0027] The second temperature monitoring component 210 is used to monitor the temperature of the semi-solid magnesium alloy slurry in the container, and the liquid level monitoring component 220 is used to monitor the liquid level of the semi-solid magnesium alloy slurry in the container.

[0028] In an optional embodiment, the second temperature monitoring component 210 is a dual-armored corrosion-resistant thermocouple that is vertically or obliquely inserted into the center region of the melt inside the container; the liquid level monitoring component 220 is a high-frequency non-contact radar liquid level gauge installed on the top cover of the container and whose signal output terminal is connected to the controller 400.

[0029] The controller 400 is electrically connected to the driver 110, the torque detection component 111, the infrared heating component 120, the first temperature monitoring component 130, the flow valve 200, the second temperature monitoring component 210, and the liquid level monitoring component 220.

[0030] Feeding control: Material safety interlock and static pressure self-compensation It should be understood that the rheological properties of semi-solid slurries are extremely sensitive to temperature and solid fraction. Material entering the rheological control chamber below the designated temperature range will cause a sharp increase in torque and may even damage the equipment. Furthermore, changes in the slurry level in the upstream container will lead to fluctuations in the outlet static pressure, resulting in passive changes in the feed rate and disrupting process stability. Therefore, by adjusting the flow valve opening in real-time with level compensation, these static pressure fluctuations can be actively offset, achieving constant pressure and constant feed rate, laying the foundation for subsequent precise rheological control.

[0031] Specifically, controller 400 is configured to execute the physical state disconnect safety interlock rule: Controller 400 reads the furnace temperature T. 炉 If the material does not reach the preset semi-solid temperature zone, it is determined that the material is unqualified, and the physical opening of the control flow valve 200 is set to 0% to perform a safety lockout; if the material reaches the semi-solid temperature zone, the control flow valve 200 is unlocked and enters the proportional regulation mode.

[0032] Furthermore, the controller 400 is also configured to execute a static pressure self-compensation rule: The controller 400 reads the real-time liquid level H in real time; when the height of the real-time liquid level H deviates from the reference design liquid level change ±∆H, the controller 400 drives the physical opening of the flow valve 200 to perform a reverse linear compensation adjustment of ∆K, wherein the quantized self-compensation relationship satisfies:

[0033] Where α is the fluid rheological viscosity boundary correction coefficient, and H0 is the initial design nominal liquid level height of the container, used to compensate for the flow rate loss caused by fluctuations in fluid static pressure and to maintain constant feeding.

[0034] Rheology control cavity structure Combination Figure 1As shown, the rheological control cavity 100 is provided with a material inlet and a slurry outlet. The material inlet is used to connect to a container that contains semi-solid magnesium alloy slurry. The rheological control cavity 100 is provided with a twin-screw structure, and the twin-screw structure and the machine body form a rheological shearing cavity. One end of the rheological shearing cavity is connected to the material inlet, and the other end is connected to the slurry outlet. The outer wall of the rheological control cavity 100 is also provided with an infrared heating component 120 and a first temperature monitoring component 130 for heating the semi-solid magnesium alloy slurry in the rheological shearing cavity. The rheological control cavity 100 is also provided with a driver 110 for driving the twin-screw structure to rotate. A torque detection component 111 is provided between the driver 110 and the twin-screw structure.

[0035] The semi-solid magnesium alloy slurry entering the rheological shear chamber is subjected to strong mechanical pushing by a twin-screw structure that rotates in the same direction and meshes with each other.

[0036] Furthermore, the rheological control chamber 100 is divided into a suction section 101, a high-shear section 102, and a homogenization discharge section 103 in the direction from the material inlet to the slurry outlet. The twin-screw structure is configured such that the pitch in the suction section 101 is L1, the pitch in the high-shear section 102 is L2, and the pitch in the homogenization discharge section 103 is L3, with L1>L2>L3.

[0037] In an optional embodiment, the pitch ratio of the three sections is L1: L2: L3 = 1.65: 1.25: 1. The length ratio of the suction section 101, the high-shear section 102, and the homogenizing discharge section 103 is 2:1:1.5.

[0038] Among them, the feeding section 101 is relatively long and has the largest pitch to ensure stable reception of slurry under low stress and low shear and to establish initial delivery pressure; the high-shear section 102 is the shortest in length but has a sharply reduced pitch, causing the slurry to undergo severe compression and shear strain in this area, thereby efficiently crushing the residual dendrite fragments and microsegregation networks in the slurry; the homogenization discharge section 103 adopts a medium length and the smallest pitch, aiming to establish extremely high axial pushing pressure to overcome the huge flow resistance of high-viscosity slurry at the mold inlet and force it to fill the downstream rheological filling crystallization mold 300.

[0039] Infrared heating components and temperature monitoring Furthermore, the infrared heating component 120 includes infrared heating coils arranged around the periphery of the rheological shear chamber. The suction section 101 is provided with infrared heating coils arranged at a first spacing P1, the high shear section 102 is provided with infrared heating coils arranged at a second spacing P2, and the homogenization discharge section 103 is provided with infrared heating coils arranged at a third spacing P3. The installation spacing of the infrared heating coils satisfies P2> P1> P3, which is used to provide non-uniform spatial heterogeneous thermal field compensation from the outside to the inside.

[0040] The infrared heating coils arranged at a first spacing P1 within the suction section 101 provide a conventional balanced heat flow boundary layer to maintain the reference target temperature from the upstream slurry.

[0041] In the high-shear section 102, the screw pitch is drastically reduced. As the rigid screw advances amidst the crushing of microcrystalline grains and strong shear, the microscopic viscosity dissipation of the high-solids slurry spontaneously releases nonlinear mechanical shear frictional heat. Therefore, the infrared filament arrangement in this section is designed to be the sparsest (with the largest spacing P2) and is subject to hardware low-power reference rating limitations.

[0042] In the homogenization and discharge section 103, the material is under the highest axial pressure, with extremely high viscosity and rapid heat loss, making it prone to forming a super-solidification dead zone on the steel wall of the cylinder. Therefore, the infrared heating coils arranged at the third spacing P3 are the densest, and their rated output power is more than 50% higher than that of the suction section.

[0043] Furthermore, the first temperature monitoring component 130 includes a first thermocouple, a second thermocouple, and a third thermocouple embedded in the pipe walls of the suction section 101, the high shear section 102, and the homogenization discharge section 103, respectively, which are used to independently collect the corresponding real-time temperatures T1, T2, and T3.

[0044] Among them, the temperature T2 collected by the second thermocouple is used as the direct dependent variable to determine whether the mechanical friction shear heat inside the high shear section is overloaded, and the temperature T3 collected by the third thermocouple, together with the real-time torque N, is used as a cascade independent variable to predict whether the pipe wall of the homogenization discharge section will freeze and form a crust.

[0045] Flow field-thermal field coordinated control and two-step cascade coordination It should be understood that the nonlinear frictional shear heat generated by semi-solid slurries in a strong shear flow field leads to thermal hysteresis in temperature control. Torque N is a direct reflection of the slurry's apparent viscosity and flow resistance, and can detect abrupt changes in rheological state caused by frictional heating or supercooling more quickly than embedded thermocouples.

[0046] High shear friction overheat dissipation rules: When the return temperature T2 of the second thermocouple of the first temperature monitoring component 130 is greater than T 目标 +3℃ (first preset temperature upper limit threshold) and real-time torque N <M min When the preset lower torque threshold is reached (indicating a risk of solid-phase remelting and crystal nucleus destruction caused by frictional heat), the controller 400 immediately shuts off the infrared coils in the high-shear section 102 (outputting a zero-current signal). The system stops all external heat input and relies solely on natural convection heat transfer between the metal wall of the barrel and the external air to actively dissipate and dissipate the internal mechanical shear heat, allowing the slurry solids fraction to quickly and spontaneously return to equilibrium.

[0047] Two-tiered coordination rules (for over-freezing risk): When the temperature T3 collected by the third thermocouple <T 目标 -3℃ (second preset lower temperature threshold) and the real-time torque N exceeds the preset upper temperature threshold M. max When the first preset torque upper limit threshold is reached, it is determined that the material in the homogenization discharge section 103 faces the risk of over-freezing and shaft seizure. The controller 400 then initiates the following two-stage control in cascade: First step (heat field priority countermeasure): The controller 400 makes a high-priority interlock response within ≤0.5 seconds, controls the radiation power of the dense infrared ring of the homogenization discharge section 103 to increase by 20~50% instantaneously, applies high-intensity and uniform surface heat flow compensation using a micro gap of ≤30mm, and performs surface heat flow feedforward compensation to melt the shell on the pipe wall in situ; and during this stage, the current opening of the flow valve 200 is kept unchanged to maintain a constant feed rate.

[0048] Second step (flow field load limit throttling): After the first step is executed, if the real-time torque N continues to rise (for example, within 3 consecutive sampling periods) and exceeds the preset equipment jamming limit threshold M, 极限 When the second preset torque upper limit threshold is reached, it is determined that simple thermal compensation is insufficient to eliminate the risk of freezing. The controller 400 starts the feedforward load reduction interlock and reduces the flow valve 200 opening degree A% within the set control response time (e.g., ≤0.1 seconds) to implement feedforward throttling and load reduction. The value of A% ranges from 20% to 50%.

[0049] By decoupling and linking the spatial heterogeneous thermal field and the flow field torque criterion, and by employing a two-step cascaded collaborative strategy of first thermal compensation and then reduction, the thermal hysteresis of traditional temperature control under nonlinear latent heat release can be effectively improved, and process interruption caused by premature reduction can be avoided.

[0050] Rheological filling crystallization mold and rheological shear structure Combination Figure 1 and Figure 4 As shown, the rheological filling crystallization mold 300 is connected to the slurry outlet of the rheological control cavity 100. The rheological filling crystallization mold 300 has a progressively variable cross-section rheological crystallization cavity 303 inside, and the diameter ratio of the inlet end 301 to the outlet end 302 of the rheological crystallization cavity 303 is 10:1. The rheological shear structure includes a flow divider cone 310 disposed inside the rheological crystallization cavity 303, and rheological shear microtexture protrusions 320 arranged in a herringbone pattern on the inner wall of the rheological crystallization cavity 303.

[0051] Specifically, under the high axial pushing pressure of the homogenization discharge section 103, the semi-solid magnesium alloy slurry is continuously pressed into the rheological filling crystallization mold 300. The remaining 40% of the liquid phase inside the slurry is subjected to three-dimensional non-uniform mechanical large shear stress by using the rheological shear microtextured protrusions 320 and the diameter ratio of 10:1. The fluid dynamic energy is converted in situ into the phase change thermodynamic driving force to generate pressure subcooling. The liquid phase is forced to undergo in situ instantaneous secondary nucleation and proliferation within a unit minute of flowing through the rheological shear distribution channel, so that the solid fraction of the slurry jumps to more than 80% in situ, so as to continuously extrude fine-grained magnesium alloy rods 500 in the forming and shaping zone.

[0052] {Example 2} The second aspect of this invention provides a technical solution: a method for semi-solid magnesium alloy rheological continuous casting injection molding implemented by the aforementioned semi-solid magnesium alloy rheological continuous casting injection molding apparatus, comprising the following steps: Step S1, Feeding Stage Control: The controller 400 reads the current furnace temperature T of the slurry in the container in real time. 炉 If the preset semi-solid temperature zone is not reached, the flow control valve 200 will be locked at zero opening. If the temperature zone is reached, the lockout will be released and the automatic proportional adjustment mode will be switched. At the same time, the material level H will be read in real time. As the height of the liquid level H increases or decreases, the opening of the flow control valve 200 will be linearly reduced or increased to implement static pressure loss self-compensation and provide a stable and full constant flow of material to the feed port of the rheological control chamber.

[0053] Step S2, Flow-thermal field coordinated control and double-step cascade coordination: The actuator 110 controls two rigid solid screws to rotate in the same direction at a constant theoretical linear velocity of 70~80m / min. The slurry undergoes high-intensity shearing under the drive of the variable pitch L1>L2>L3 flow field to pulverize the macroscopic segregation network; during this process, the controller 400 continuously reads the real-time torque N and the temperature of each segment: When the high shear segment temperature T2>T is detected 目标 +3℃ and real-time torque N <M min When the high shear friction overheating is detected, the infrared heating coil in the high shear section is turned off to actively dissipate heat. When the temperature T3 of the homogenization discharge section is detected <T 目标 -3℃ and real-time torque N>M max When the backend over-freeze warning is triggered, the controller 400 cascades and initiates a two-stage coordinated operation: First step: Control the infrared heating coil power of the homogenization discharge section 103 to increase by 20%~50%, execute the thermal field priority counter-current, and keep the current opening of the flow valve 200 unchanged; Second step: If, after the first step is executed, the real-time torque N continues to rise and exceeds the equipment jamming limit threshold M... 极限Then, within the set control response time (e.g., ≤0.1 seconds), the flow valve opening is reduced by 200% A% to implement feedforward throttling and load reduction, where the value of A% ranges from 20% to 50%.

[0054] Through the aforementioned coordinated control, the solid fraction of the slurry at the slurry outlet is stably controlled to a preset value, and the corresponding real-time temperature is controlled at the preset semi-solid target temperature T. 目标 Within the metastable temperature range of ±3℃.

[0055] Step S3, In-situ Secondary Nucleation and Crystallization within the Mold: Relying on the high axial pushing pressure established by the homogenizing discharge section 103, the slurry treated in step S2 is forcibly and continuously pushed into the rheological filling crystallization mold 300. Inside the rheological filling crystallization mold 300, the 10:1 diameter compression ratio forces the slurry cross-section to shrink rapidly. At the same time, the central flow divider guides the slurry to the wall surface, and together with the herringbone-shaped cross-shear microtexture protrusions on the side wall, a high-density three-dimensional mechanical stress shear is applied to the slurry. These mechanical shear forces forcibly break up any remaining coarse structures and inhibit component segregation during the crystallization and solidification process. Finally, under the combined action of continuous pushing from the rheological control cavity and continuous constraint forming of the mold, a high-performance magnesium alloy rod with an equiaxed spherical fine-grained microstructure is continuously formed and stably cast.

[0056] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A semi-solid magnesium alloy rheological continuous casting injection molding apparatus, characterized in that, include: The rheological control chamber (100) is provided with a material inlet for connecting to a semi-solid magnesium alloy slurry container and a slurry outlet. Inside, there is a twin-screw structure that forms a rheological shearing chamber with the machine body, which is used to shear and break up the semi-solid magnesium alloy slurry to suppress dendrite growth. The outer wall of the rheological control chamber (100) is provided with an infrared heating component (120) and a first temperature monitoring component (130). It is also provided with a driver (110) that drives the twin-screw structure. A torque detection component (111) is provided between the driver (110) and the twin-screw structure. A flow valve (200) is connected to the material inlet to control the flow rate of the semi-solid slurry entering the rheological shear chamber; A rheological filling crystallization mold (300) is connected to the slurry outlet; The controller (400) is electrically connected to the driver (110), torque detection component (111), infrared heating component (120), first temperature monitoring component (130), and flow valve (200); The controller (400) is configured to: maintain the twin-screw structure rotating at the target speed, use the real-time torque N collected by the torque detection component (111) as the criterion for the apparent viscosity and phase change load of the semi-solid slurry, cascade control the opening of the flow valve (200) and the radiation power of the infrared heating component (120) to compensate for the temperature control lag caused by the latent heat of phase change and frictional shear heat, so that the real-time temperature collected by the first temperature monitoring component (130) is controlled within the preset semi-solid target temperature range, and continuously press the slurry into the rheological filling crystallization mold (300) to continuously solidify and form fine-grained magnesium alloy rods (500).

2. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 1, characterized in that, The rheological control chamber (100) is divided into a suction section (101), a high shear section (102), and a homogenization discharge section (103) in the direction from the material inlet to the slurry outlet. The twin-screw structure is configured such that the pitch in the suction section (101) is L1, the pitch in the high shear section (102) is L2, and the pitch in the homogenization discharge section (103) is L3, with L1>L2>L3.

3. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 2, characterized in that, The infrared heating component (120) includes an infrared heating ring arranged around the rheological shearing chamber. The suction section (101) is provided with an infrared heating ring arranged at a first spacing P1, the high shear section (102) is provided with an infrared heating ring arranged at a second spacing P2, and the homogenization discharge section (103) is provided with an infrared heating ring arranged at a third spacing P3. The installation spacing of the infrared heating rings satisfies P2> P1> P3.

4. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 2, characterized in that, The first temperature monitoring component (130) includes a first thermocouple, a second thermocouple, and a third thermocouple embedded in the pipe walls of the suction section (101), the high shear section (102), and the homogenization discharge section (103), respectively, which are used to independently collect the corresponding real-time temperatures T1, T2, and T3.

5. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 1, characterized in that, Also includes: a second temperature monitoring component (210) for monitoring a current furnace temperature T of the semi-solid magnesium alloy slurry in the vessel 炉 ; A liquid level monitoring component (220) is used to monitor the real-time liquid level H of the semi-solid magnesium alloy slurry in the container; The second temperature monitoring component (210) and the liquid level monitoring component (220) are electrically connected to the controller (400), which is configured to: acquiring a furnace temperature T measured by the second temperature monitoring component (210) 炉 and only when the furnace temperature reaches a preset semi-solid temperature zone, unlocking the flow valve (200) to allow feeding; The liquid level H measured by the liquid level monitoring component (220) is obtained, and the opening degree of the flow valve (200) is adjusted in the opposite direction according to the change of the liquid level H to compensate for static pressure fluctuations.

6. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 4, characterized in that, The controller (400) is also configured to: Based on the real-time torque N collected by the torque detection component (111) and the real-time temperature collected by the first temperature monitoring component (130), flow field-thermal field coordinated control is performed, the coordinated control including: When the real-time temperature T2 in the high-shear section (102) exceeds the first preset upper temperature threshold and the real-time torque N is lower than the preset lower torque threshold, the heating power of the infrared heating component (120) in the region corresponding to the high-shear section (102) is reduced or turned off. When the real-time temperature T3 in the homogenization discharge section (103) is lower than the second preset lower limit threshold and the real-time torque N exceeds the first preset upper limit threshold, thermal compensation and flow regulation are performed.

7. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 6, characterized in that, The controller's thermal compensation and flow regulation adopt a two-tiered, sequential collaborative rule: First-stage control: Within a set response time, the radiation power of the infrared heating component (120) corresponding to the homogenization discharge section (103) is increased according to a first preset ratio, while the current opening of the flow valve (200) remains unchanged; Second-stage control: If the real-time torque N continues to rise and exceeds the second preset torque upper limit threshold after the first-stage control is executed, the flow valve (200) is controlled to reduce the opening of the preset ratio to implement flow throttling and load reduction.

8. The semi-solid magnesium alloy rheological continuous casting injection molding apparatus according to claim 7, characterized in that, The rheological filling crystallization mold (300) has a progressively variable cross-section rheological crystallization cavity (303) inside. The rheological crystallization cavity (303) is provided with a rheological shear structure for applying three-dimensional shear stress to the semi-solid magnesium alloy slurry passing through. The rheological shear structure includes a flow divider cone (310) disposed inside the rheological crystallization cavity (303) and rheological shear microtexture protrusions (320) arranged in a herringbone pattern on the inner wall of the rheological crystallization cavity (303).

9. A method for continuous rheological casting and injection molding of semi-solid magnesium alloy, characterized in that, The semi-solid magnesium alloy rheological continuous casting injection molding apparatus as described in claim 8 includes the following steps: Step S1: Control the flow valve (200) through the controller (400) to feed the temperature-controlled semi-solid magnesium alloy slurry into the rheological control chamber (100) at a constant flow rate; Step S2: The variable pitch twin-screw structure of the rheological control cavity (100) shears and conveys the slurry. The controller (400) adjusts the opening of the flow valve (200) and the power of the infrared heating component (120) in a cascade manner according to the real-time torque N of the torque detection component (111) and the real-time temperature of the first temperature monitoring component (130). Step S3: The slurry processed in step S2 is continuously pressed into the rheological filling and crystallization mold (300). The rheological shear structure applies three-dimensional shear stress to the slurry, causing it to undergo in-situ secondary nucleation, and high solids magnesium alloy rods are continuously cast.

10. The semi-solid magnesium alloy rheological continuous casting injection molding method according to claim 9, characterized in that, In step S2, the cascaded control includes: When the real-time temperature T2 of the high-shear section (102) exceeds the first preset upper temperature threshold and the real-time torque N is lower than the preset lower torque threshold, the heating power of the corresponding area is reduced or turned off; when the real-time temperature T3 of the homogenization discharge section (103) is lower than the second preset lower temperature threshold and the real-time torque N exceeds the first preset upper torque threshold, the first step control is executed sequentially to perform external heat flow compensation and the second step control is executed to reduce the feeding amount.

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