Method for controlling extrusion of aluminum profiles

Abstract

The application discloses an extrusion forming control method of aluminum profile, which comprises the following steps: homogenizing heat treatment of aluminum blank and determination of process parameters; placing the aluminum blank into a ingot cylinder provided with at least three independent heating zones with gradient heating along the extrusion direction; performing variable pressure extrusion with low-speed constant-speed deceleration in stages, and applying radial ultrasonic vibration to the ingot cylinder during the extrusion process; after extrusion, gradient quenching is performed by using water mist with decreasing strength along the extrusion direction; and finally, the finished product is obtained through stretching straightening including pre-stretching and multi-pass fine straightening. The application improves the metal flow uniformity, reduces the size deviation and shape defects by coupling ultrasonic vibration through gradient heating and segmented extrusion, and improves the profile surface quality by combining gradient quenching and multi-stage straightening.

Description

Technical Field

[0001] This invention relates to the field of aluminum profile manufacturing technology, and specifically to a method for controlling the extrusion molding of aluminum profiles. Background Technology

[0002] Aluminum profiles, as an engineering material that combines lightweight, high strength, corrosion resistance, and excellent processing performance, have been widely used in construction, transportation, electronics, industrial automation, and new energy equipment.

[0003] The production of aluminum profiles mainly relies on extrusion molding, which uses a die to plastically deform heated aluminum billets. First, the aluminum alloy ingot is sawn and subjected to homogenization heat treatment to form a billet. The billet is then heated to a plastic temperature range of approximately 400-500°C and placed in the billet cylinder of an extruder. Under pressure, the billet flows through the die orifice, forming a continuous profile with a specific cross-sectional shape. The extruded profile undergoes processes such as traction straightening, online quenching and cooling, length sawing, aging treatment, and anodizing or spraying to finally obtain the corresponding product.

[0004] However, due to factors such as uneven metal flow, elastic deformation, and temperature fluctuations, extruded aluminum profiles are prone to shape defects such as dimensional deviations, bending, and twisting, especially for thin-walled or complex cross-section products. Surface scratches, lines, and even microcracks are easily generated, affecting appearance and durability, and hindering subsequent anodizing processes.

[0005] Therefore, it is necessary to improve and optimize the extrusion molding method for aluminum profiles. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for controlling the extrusion molding of aluminum profiles with higher product quality.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows.

[0008] A method for controlling the extrusion molding of aluminum profiles, comprising the following steps: S01. Obtain the aluminum profile blank, perform homogenization heat treatment on it to bring it to the plastic temperature range, and determine the extrusion process parameters according to the cross-sectional shape and size specifications of the target profile. S02. Place the billet into the billet holder of the extruder. The billet holder is provided with at least three independently temperature-controlled heating zones along the extrusion direction. The temperature of each heating zone increases gradually from the feed end to the discharge end. S03. Start the extruder and extrude the billet in stages. In the initial stage, a first pressure is used for low-speed extrusion. In the stable stage, the pressure is increased to a second pressure for constant-speed extrusion. In the final stage, the pressure is reduced to a third pressure for deceleration extrusion. S04. During the staged extrusion process, the billet cylinder is subjected to ultrasonic vibration; S05. After the profile is extruded, it is subjected to water mist cooling quenching, and the cooling intensity of the water mist cooling gradually decreases along the extrusion direction. S06. After cooling, the profile is stretched and straightened, then sawn to a fixed length and aged to obtain the finished aluminum profile.

[0009] As a preferred technical solution, in step S01, the components of the aluminum profile blank, by mass percentage, include: Si, 0.4-0.8%; Mg, 0.6-1.2%; Zr, 0.05-0.25%; Fe≤0.35%; Cu≤0.10%; Mn≤0.15%; Cr≤0.05%; Zn≤0.10%; Ti0.01-0.05%, with the balance being Al and unavoidable impurities.

[0010] As a preferred technical solution, in step S01, determining the extrusion process parameters based on the cross-sectional shape and size specifications of the target profile includes: for complex profiles with a wall thickness difference greater than 5mm or an asymmetrical cross-sectional shape, the first pressure is set to 60%-70% of the rated pressure of the extruder, the second pressure is set to 85%-95%, and the third pressure is set to 40%-50%. For symmetrical profiles with uniform wall thickness, the first pressure is 55%-65% of the rated pressure, the second pressure is 80%-90%, and the third pressure is 45%-55%.

[0011] As a preferred technical solution, in step S02, the temperature gradient configuration of the heating zone of the billet cylinder includes setting the temperature of the first zone at the feeding end to 400±10℃ and setting the temperature of the last zone at the discharging end to the upper limit of the target plastic temperature of the billet.

[0012] As a preferred technical solution, in step S03, the pressure and speed of the staged extrusion include: in the initial low-speed extrusion stage, the extrusion speed is controlled at 0.5-2 mm / s; in the stable constant-speed extrusion stage, the extrusion speed is increased to 3-8 mm / s; and in the final deceleration extrusion stage, the extrusion speed is reduced to 0.5-1.5 mm / s.

[0013] As a preferred technical solution, in step S04, the direction of the ultrasonic vibration is radial to the ingot container, and the vibration frequency is 15-22kHz.

[0014] As a preferred technical solution, in step S04, the amplitude of ultrasonic vibration is related to the extrusion speed in step S03. When the extrusion speed is in the range of 3-5 mm / s, the ultrasonic amplitude is controlled at 8-12 μm; when the extrusion speed is greater than 5 mm / s, the ultrasonic amplitude is controlled at 12-18 μm.

[0015] As a preferred technical solution, in step S05, the profile immediately enters the quenching zone composed of multiple independent spray sections after demolding; along the extrusion direction, the flow rate of cooling water mist in the first spray section decreases progressively towards each subsequent section, with a decrease ratio of 10%-20% for each spray section; the water mist temperature in the first spray section is not higher than 30°C, and the water mist temperature in the final spray section is not higher than 60°C.

[0016] As a preferred technical solution, in step S06, the stretching and straightening includes a pre-stretching stage and a fine straightening stage; The pre-stretching stage applies a stretching rate of 0.3%-0.8%; The fine straightening stage involves using multiple sets of staggered straightening rollers to repeatedly bend and straighten the profile through multiple passes, with the relative bending deformation in each pass controlled within the range of 0.5%-1.5%.

[0017] As a preferred technical solution, the extruder ingot cylinder includes a cylinder body and an electromagnetic heating coil arranged sequentially from the inside to the outside; multiple independent electromagnetic heating coils divide the cylinder body into at least three independently temperature-controlled heating zones along the extrusion direction; multiple sets of axially extending resonant cavities are uniformly opened circumferentially in the wall thickness direction of the cylinder body, the axial length of the resonant cavity is 1 / 4 or 1 / 2 of the wavelength of the ultrasonic treatment sound wave, and the thickness of the resonant cavity is 1 / 3 to 2 / 3 of the sleeve wall thickness.

[0018] The advantages and beneficial effects of this invention are as follows: By using gradient heating, step pressurization and ultrasonic vibration, the plastic deformation process of the metal is precisely controlled, so that the aluminum profile billet forms a reasonable temperature field and plastic gradient in the extrusion direction, thereby allowing the billet to flow smoothly; corresponding pressures are matched for different extrusion stages; the radially applied ultrasonic vibration not only reduces the friction between the billet and the cylinder wall, but also induces beneficial micro-plastic deformation and dynamic recrystallization inside the material at specific frequency and amplitude parameters, alleviating the problem of internal stress concentration caused by non-uniform phase transformation.

[0019] Traditional aluminum alloy composition design primarily focuses on the mechanical and corrosion resistance properties of the final product. However, this invention specifically adds 0.05-0.25% zirconium to the billet. During the homogenization heat treatment, Zr precipitates as a fine Al3Zr dispersed phase. This phase acts as a vibration energy transfer node, promoting uniform softening of the overall material and refining the grain structure after dynamic recrystallization. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the extruder ingot holder shown in this invention.

[0021] Figure label: 1-Cylinder, 2-Electromagnetic heating coil, 3-Resonant cavity. Detailed Implementation

[0022] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] This invention provides a method for controlling the extrusion molding of aluminum profiles. Through a series of control measures, it solves problems such as uneven metal flow, temperature fluctuations, stress concentration, and subsequent cooling deformation that occur during the aluminum profile extrusion molding process, thereby improving the dimensional accuracy, shape stability, surface quality, and mechanical properties of the product. The method specifically includes the following steps: S01. Obtain aluminum profile blanks, perform homogenization heat treatment on them to bring them to the plastic temperature range, and determine the extrusion process parameters according to the cross-sectional shape and size specifications of the target profile. S02. The billet is placed into the billet cylinder of the extruder. The billet cylinder is provided with at least three independently temperature-controlled heating zones along the extrusion direction. The temperature of each heating zone increases in a gradient from the feed end to the discharge end. S03. Start the extruder and extrude the billet in stages. In the initial stage, the first pressure is used for low-speed extrusion. In the stable stage, the pressure is increased to the second pressure for constant-speed extrusion. In the final stage, the pressure is reduced to the third pressure for deceleration extrusion. S04. During the staged extrusion process, ultrasonic vibration is applied to the ingot container. S05. After the profile is extruded, it is subjected to water mist cooling quenching, and the cooling intensity gradually decreases along the extrusion direction. S06. After cooling, the profile is stretched, straightened, cut to length, and aged to obtain the finished aluminum profile.

[0026] This method first involves sawing the aluminum alloy ingot to obtain a billet of specified dimensions, followed by a homogenization heat treatment. The purpose of homogenization is to eliminate dendritic segregation and low-melting-point eutectic phases within the ingot, ensuring that alloying elements (especially Mg, Si, Zr, etc.) are fully dissolved and uniformly distributed, thereby improving the plasticity uniformity of the billet during subsequent heating and extrusion processes. The heat treatment temperature is typically set slightly below the alloy solidus, approximately 530-580℃, and held for a sufficient time, approximately 3-5 hours.

[0027] This invention specifically selects the alloy composition of the billet, which, by mass percentage, comprises: Si 0.4-0.8%, Mg 0.6-1.2%, Zr 0.05-0.25%, Fe ≤0.35%, Cu ≤0.10%, Mn ≤0.15%, Cr ≤0.05%, Zn ≤0.10%, Ti 0.01-0.05%, with the balance being Al and unavoidable impurities. During the homogenization process, Zr can precipitate as a nano- or submicron-sized Al3Zr dispersed phase. These Al3Zr particles, in the subsequent plastic deformation process, can act as pinning points for dislocation movement, refining the dynamically recrystallized grains. Furthermore, in the ultrasonic vibration field applied in step S04, these hard dispersed phases can serve as efficient energy transfer nodes and reflection sources, promoting the uniform absorption and dissipation of vibration energy within the billet, inducing more uniform micro-plastic deformation within the material, thereby further improving the uniformity of metal flow at the microscopic level and alleviating stress concentration.

[0028] The homogenized billet is heated to its plasticity temperature range. Within this range, aluminum alloys exhibit optimal plastic deformation capacity and relatively low deformation resistance. It is necessary to comprehensively consider the complexity of the target profile's cross-sectional shape, wall thickness uniformity, dimensional specifications (such as circumscribed circle diameter and minimum wall thickness), and extrusion ratio. This invention emphasizes pre-setting staged pressure and speed parameters based on the profile characteristics. Improper parameter settings, such as excessively high initial pressure or excessively high speed, may lead to bulging or incomplete filling at the front end of the billet; while improper parameters in the final stage may cause tail-end shrinkage or surface cracks in the profile.

[0029] For complex profiles with asymmetrical cross-sections and uneven wall thicknesses, the differences in metal flow resistance are significant. To prevent incomplete filling or tearing of thin-walled sections, extrusion process parameters should be controlled as follows: the extrusion ratio should not exceed 35; the initial stage pressure should be set at a relatively high level (e.g., 65%-70% of the rated pressure); and the speed should be slowed down (e.g., 1.0-2.0 mm / s) to ensure that the metal can smoothly and fully fill all corners of the die. In the final stage, the pressure needs to be significantly reduced to a lower level (e.g., 40%-45% of the rated pressure) to smoothly conclude the process and prevent tail-end shrinkage due to material shortage.

[0030] For simple profiles with symmetrical and thick walls, the metal flow is relatively uniform. To improve efficiency, the extrusion ratio can be increased to over 45. More balanced parameters can be adopted for the pressure and speed in the initial and steady stages (e.g., initial pressure 60%, speed 1.5-2.5 mm / s; steady stage pressure 85%, speed 4-6 mm / s).

[0031] This invention employs an extruder billet cylinder with at least three independently temperature-controlled heating zones. Preferably, the temperature of the first zone at the feed end is set at 400±10℃, while the temperature of the last zone at the discharge end is set to the upper limit of the target plasticity temperature of the billet (e.g., 480-500℃). In the initial stage of extrusion, the lower temperature at the feed end softens the surface of the billet while maintaining relatively high strength in the core, helping to form a stable "cushion" under pressure and preventing metal turbulence. As extrusion progresses, the billet moves towards the higher temperature zone, the overall temperature gradually increases, plasticity further improves, and deformation resistance decreases, ensuring that the metal flows smoothly and continuously through the die. This compensates for the uneven temperature rise caused by deformation heat and frictional heat during extrusion, maintaining a relatively ideal and stable plastic state for the billet throughout the entire extrusion stroke.

[0032] In this invention, the extrusion process is divided into three stages: initial, stable, and final, with each stage matched with different pressures and speeds.

[0033] During the initial low-speed extrusion stage, the extrusion speed is controlled at 0.5-2 mm / s. The main purpose is to allow the billet to slowly and fully fill the front space of the billet cylinder and begin to flow through the die guide holes. Low speed helps to observe and adjust the filling state, avoiding gas entrapment or incomplete filling due to excessive speed. The first pressure is set at 55%-70% of the rated pressure, providing sufficient driving force to initiate deformation while avoiding excessive impact loads.

[0034] During the stable, constant-speed extrusion stage, once the billet is fully filled and the flow reaches a steady state, the extrusion speed is increased to 3-8 mm / s, and the pressure is raised to the second pressure level to control the forming of the profile body. The relatively high constant speed ensures production efficiency, while the high pressure ensures that the metal can overcome die resistance and flow out continuously and stably, resulting in a dense and uniform microstructure. Excessive speed may lead to uncontrolled metal flow and excessively high surface temperature, causing hot cracks; insufficient speed results in low production efficiency and may cause the billet to remain in the billet cylinder for too long, leading to overheating.

[0035] In the final deceleration extrusion stage, as the remaining portion of the billet passes through the die, the speed is reduced to 0.5-1.5 mm / s, and the pressure is lowered to the third pressure, resulting in a smooth finish. At this point, the billet volume decreases, and the boundary conditions for metal flow change. Deceleration and pressure reduction can effectively prevent defects such as tail-end shrinkage and splitting caused by the back-pull effect.

[0036] During the staged extrusion process, this invention applies radial high-frequency micro-amplitude vibration to the billet cylinder, which is transmitted to the surface of the billet through the cylinder wall. This reduces the friction between the billet and the cylinder wall, making the friction state tend towards a "stick-slip" or fluid lubrication state. On the one hand, it reduces the deformation force required for extrusion (approximately 5%-15%), and improves the uniformity of metal surface flow, reducing surface scratches and dead zones.

[0037] When ultrasonic energy is transmitted into the blank, it can also cause changes in the periodic stress and dislocation density of the material. Vibration energy promotes dislocation disengagement and movement, which is equivalent to reducing the yield strength of the material, allowing the metal to deform under less pressure. At specific frequencies and amplitudes, the accumulation of vibration energy can induce grain boundary migration and recrystallization nucleation, thereby refining the recrystallized grains during the extrusion process and improving the uniformity of the mechanical properties of the profile.

[0038] The amplitude of ultrasonic vibration needs to be dynamically matched with the extrusion speed. During stable extrusion, the metal flow is relatively smooth, and a smaller amplitude of 8-12 μm is sufficient to effectively reduce friction and soften the metal, avoiding excessive flow disturbance. During high-speed extrusion, the metal flow is intense, and frictional and deformation heat increases. A larger amplitude of 12-18 μm can inject more energy, which helps to counteract the adverse thermal effects and flow instability caused by high speed, ensuring the full effectiveness of the vibration.

[0039] To achieve effective ultrasonic induction and precise gradient temperature control, the ingot container can employ a structure consisting of a cylinder 1 arranged sequentially from the inside out and multiple independent electromagnetic heating coils 2. The electromagnetic heating coils are arranged in axial segments, each segment corresponding to a heating zone, and controlled in a closed-loop manner by an independent temperature control system. Multiple sets of axially extending resonant cavities 3 are uniformly formed circumferentially along the wall thickness direction of the ingot container. The axial length of the resonant cavity should be designed to be 1 / 4 or 1 / 2 (approximately 5-10 mm) of the wavelength of the ultrasonic wave used in the ultrasonic treatment, and the thickness should be 1 / 3 to 2 / 3 (approximately 2-4 mm) of the cylinder wall thickness. This makes the cylinder itself a highly efficient ultrasonic resonator, capable of converting the longitudinal vibration generated by the ultrasonic transducer into radial vibration acting on the billet and reducing energy loss within the cylinder.

[0040] The ultrasonic unit shown in this invention includes a bushing that is wound around the outer periphery of the resonant cavity. The outer side of the bushing is connected to the ultrasonic transducer. Preferably, the electrical system of the ultrasonic device is implemented using high-temperature resistant cables at a distance of more than two meters from the electromagnetic coil. The connection between the resonant cavity and the bushing can be made of rigid heat-resistant materials, such as ceramics, for vibration transmission, so as to keep the ultrasonic unit working normally.

[0041] After the profile is extruded through the die, its temperature remains as high as approximately 500°C, requiring rapid cooling (quenching) to fix the high-temperature solution state. Traditional water cooling or forced air cooling is prone to uneven cooling, leading to inconsistent shrinkage in different parts of the profile, resulting in bending, twisting, or significant residual stress. This invention employs water mist quenching with gradually decreasing cooling intensity along the extrusion direction.

[0042] Specifically, immediately after the profile exits the mold, it enters a quenching zone consisting of multiple independent spray sections. Along the extrusion direction (i.e., the profile's forward direction), the first spray section (closest to the mold) has the highest cooling water mist flow rate and impact force, with a water temperature not exceeding 30°C, to achieve rapid "sudden cooling" of the high-temperature profile and quickly pass through the quenching-sensitive zone. The flow rate of each subsequent spray section decreases progressively, preferably by 10%-20% per section, and the water mist temperature of the final spray section does not exceed 60°C.

[0043] During the extrusion process, the head of the profile exits the mold first and cools first, while the tail exits later and cools later, resulting in a natural time and temperature difference. If uniform, rapid cooling is used, the tail may enter the cooling zone while the head has already cooled to a lower temperature, leading to significant thermal stress due to this large temperature difference. Gradient cooling, on the other hand, creates a relatively gentle temperature drop curve along the length of the profile, reducing the amount of temperature change along the length. This reduces longitudinal bending stress and transverse torsional deformation caused by uneven shrinkage, thus improving the straightness of the profile.

[0044] After quenching, the profiles still need to be straightened. This invention first applies a tensile treatment of 0.3%-0.8% to the profile. Through this overall micro-stretching, the fibers in various parts of the profile are straightened, eliminating or reducing macroscopic longitudinal bending, and making the residual stress distribution more symmetrical and uniform. Too low a stretching rate has little effect; too high a rate may lead to profile cross-section deformation or the generation of new uneven plastic deformation.

[0045] After pre-stretching, multiple sets of staggered straightening rollers are used to repeatedly bend and straighten the profile in multiple passes. Each set of straightening rollers applies a reverse bending moment to the profile. Through repeated bending with multiple passes and small deformations, minor local bends and unevenness of the profile can be corrected gradually and precisely, and micro-stress can be further homogenized.

[0046] The profiles, after being stretched and straightened, are then cut to a fixed length and then subjected to aging treatment (for example, for 6061 alloy, they are usually held at around 175°C for 8 hours).

[0047] The present invention will be further explained and illustrated below with reference to the embodiments.

[0048] Example 1 This embodiment provides a method for controlling the extrusion molding of aluminum profiles, and the specific steps are as follows: S01. Obtain 6061 series aluminum alloy billet, whose composition by mass percentage is: Si 0.6%, Mg 0.9%, Zr 0.12%, Fe 0.25%, Cu 0.05%, Mn 0.10%, Cr 0.02%, Zn 0.05%, Ti 0.03%, with the balance being Al and unavoidable impurities. The billet undergoes homogenization heat treatment: held at 540℃ for 4 hours, then cooled in the furnace. It is then heated to the plastic temperature range of 480℃.

[0049] S02. The heated billet is placed into the billet holder of the extruder. The billet holder is equipped with five independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient is configured as follows: Zone 1 at the feed end: 405℃, Zone 2: 435℃, Zone 3: 455℃, Zone 4: 470℃, and Zone 5 at the discharge end: 490℃.

[0050] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (68% of the rated pressure) and control the extrusion speed at 1.2 mm / s.

[0051] Stable constant speed extrusion stage: The pressure is increased to the second pressure (92% of the rated pressure), and the extrusion speed is increased to 6.5 mm / s.

[0052] Final deceleration extrusion stage: The pressure is reduced to the third pressure (48% of the rated pressure), and the extrusion speed is reduced to 1.0 mm / s.

[0053] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 18 kHz. The ultrasonic amplitude is controlled at 15 μm.

[0054] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of four independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 28℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 15%; the water mist temperature of the final fourth spray section is 55℃.

[0055] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.5%.

[0056] Fine straightening stage: The profile is repeatedly bent and straightened in three passes by seven sets of staggered straightening rollers, with the relative bending deformation in each pass controlled at 1.0%.

[0057] Finally, the aluminum profiles are cut to a fixed length and then artificially aged at 175°C for 8 hours to obtain the finished aluminum profiles.

[0058] The profile produced in this embodiment has a smooth appearance, free from visible twisting, wavy lines, scratches, and cracks. Dimensional tolerances meet the high-precision requirements of GB / T 14846-2014. Tests show its yield strength is 295 MPa, tensile strength is 325 MPa, and elongation at break is 11.5%.

[0059] Example 2 This example provides a method for controlling the extrusion molding of aluminum profiles. The specific steps are as follows: S01. Obtain 6082 series aluminum alloy billet, whose composition by mass percentage is: Si 0.7%, Mg 1.0%, Zr 0.08%, Fe 0.20%, Cu 0.08%, Mn 0.12%, Cr 0.03%, Zn 0.08%, Ti 0.02%, with the balance being Al and unavoidable impurities. The billet undergoes homogenization heat treatment: held at 550℃ for 5 hours, then cooled in the furnace. It is then heated to the plastic temperature range of 460℃.

[0060] S02. The heated billet is placed into the billet holder of the extruder. The billet holder is equipped with four independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient is configured as follows: Zone 1 at the feed end: 410℃, Zone 2: 440℃, Zone 3: 460℃, and Zone 4 at the discharge end: 480℃.

[0061] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (60% of the rated pressure) and control the extrusion speed at 1.5 mm / s.

[0062] Stable constant speed extrusion stage: The pressure is increased to the second pressure (85% of the rated pressure), and the extrusion speed is increased to 4.0 mm / s.

[0063] Final deceleration extrusion stage: The pressure is reduced to the third pressure (50% of the rated pressure), and the extrusion speed is reduced to 1.2 mm / s.

[0064] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 16 kHz. The ultrasonic amplitude is controlled at 10 μm.

[0065] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of three independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 26℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 12%; the water mist temperature of the final third spray section is 52℃.

[0066] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.6%.

[0067] Fine straightening stage: The profile is repeatedly bent and straightened in two passes using five sets of staggered straightening rollers, with the relative bending deformation controlled at 0.8% in each pass. Finally, it is cut to length and artificially aged at 180℃ for 6 hours to obtain the finished aluminum profile.

[0068] The profile produced in this embodiment has a smooth and flat surface, free from visible bending, twisting, and surface defects. Its straightness reaches 0.8 mm / m, meeting the requirements of GB / T 14846-2014 for ordinary grade. Tests show its yield strength is 285 MPa, tensile strength is 315 MPa, and elongation at break is 12.0%.

[0069] Example 3 This example provides a method for controlling the extrusion molding of aluminum profiles. The specific steps are as follows: S01. Obtain 6005A series aluminum alloy billet, whose composition by mass percentage is: Si 0.5%, Mg 0.8%, Zr 0.18%, Fe 0.30%, Cu 0.03%, Mn 0.08%, Cr 0.04%, Zn 0.06%, Ti 0.04%, with the balance being Al and unavoidable impurities. The billet undergoes homogenization heat treatment: holding at 535℃ for 4.5 hours, followed by furnace cooling. Then, it is heated to the plastic temperature range of 470℃.

[0070] S02. The heated billet is placed into the billet holder of the extruder. The billet holder is equipped with six independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient is configured as follows: Zone 1 at the feed end: 400℃, Zone 2: 425℃, Zone 3: 445℃, Zone 4: 460℃, Zone 5: 475℃, and Zone 6 at the discharge end: 485℃.

[0071] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (66% of the rated pressure) and control the extrusion speed at 1.0 mm / s.

[0072] Stable constant speed extrusion stage: The pressure is increased to the second pressure (90% of the rated pressure), and the extrusion speed is increased to 5.5 mm / s.

[0073] Final deceleration extrusion stage: The pressure is reduced to the third pressure (46% of the rated pressure), and the extrusion speed is reduced to 0.8 mm / s.

[0074] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 20 kHz. Based on the velocity during the steady-state phase, the ultrasonic amplitude is controlled at 13 μm.

[0075] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of five independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 24℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 18%; the water mist temperature of the fifth spray section at the end is 58℃.

[0076] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.4%.

[0077] Fine straightening stage: The profile is repeatedly bent and straightened in three passes using six sets of staggered straightening rollers, with the relative bending deformation controlled at 1.1% in each pass. Finally, it is cut to length and artificially aged at 170℃ for 10 hours to obtain the finished aluminum profile.

[0078] The profile produced in this embodiment has high dimensional accuracy, with wall thickness tolerance controlled within ±0.08mm, and a smooth, scratch-free surface. Testing showed that its yield strength is 290 MPa, tensile strength is 320 MPa, and elongation at break is 11.0%.

[0079] Example 4 This example provides a method for controlling the extrusion molding of aluminum profiles. The specific steps are as follows: S01. Obtain 6063 series aluminum alloy billet, whose composition by mass percentage is: Si 0.4%, Mg 0.7%, Zr 0.22%, Fe 0.15%, Cu 0.10%, Mn 0.05%, Cr 0.05%, Zn 0.10%, Ti 0.01%, with the balance being Al and unavoidable impurities. The billet undergoes homogenization heat treatment: holding at 520℃ for 6 hours, followed by furnace cooling. Then, it is heated to the plastic temperature range of 490℃.

[0080] S02. The heated billet is placed into the billet holder of the extruder. The billet holder is equipped with three independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient is configured as follows: Zone 1 at the feed end 398℃, Zone 2 450℃, and Zone 3 at the discharge end 495℃.

[0081] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (62% of the rated pressure) and control the extrusion speed at 1.8 mm / s.

[0082] Stable constant speed extrusion stage: The pressure is increased to the second pressure (88% of the rated pressure), and the extrusion speed is increased to 7.0 mm / s.

[0083] Final deceleration extrusion stage: The pressure is reduced to the third pressure (52% of the rated pressure), and the extrusion speed is reduced to 1.4 mm / s.

[0084] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 17 kHz. Based on the velocity during the steady-state phase, the ultrasonic amplitude is controlled at 16 μm.

[0085] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of four independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 29℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 11%; the water mist temperature of the final fourth spray section is 59℃.

[0086] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.7%.

[0087] Fine straightening stage: The profile is repeatedly bent and straightened in two passes using four sets of staggered straightening rollers, with the relative bending deformation controlled at 0.9% in each pass. Finally, it is cut to length and artificially aged at 185℃ for 5 hours to obtain the finished aluminum profile.

[0088] The profile produced in this embodiment has a dense macrostructure and is free from defects such as shrinkage and splitting. Testing showed that its yield strength was 280 MPa, tensile strength was 305 MPa, and elongation at break was 13.5%.

[0089] Example 5 This example provides a method for controlling the extrusion molding of aluminum profiles. The specific steps are as follows: S01. Obtain 7075 series aluminum alloy billet, whose composition by mass percentage is: Si 0.10%, Mg 2.5%, Zr 0.25%, Fe 0.18%, Cu 1.6%, Mn 0.03%, Cr 0.20%, Zn 5.8%, Ti 0.05%, with the balance being Al and unavoidable impurities. The billet undergoes homogenization heat treatment: holding at 465℃ for 24 hours, followed by cooling to room temperature at a rate of 30℃ / hour. Then, it is heated to the plastic temperature range of 430℃. S02. Place the heated billet into the billet holder of the extrusion press. This billet holder has five independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient configuration is: zone 1 at the feed end 420℃, zone 2 425℃, zone 3 430℃, zone 4 432℃, and zone 5 at the discharge end 435℃.

[0090] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (70% of the rated pressure) and control the extrusion speed at 0.8 mm / s.

[0091] Stable constant speed extrusion stage: The pressure is increased to the second pressure (95% of the rated pressure), and the extrusion speed is increased to 3.5 mm / s.

[0092] Final deceleration extrusion stage: The pressure is reduced to the third pressure (55% of the rated pressure), and the extrusion speed is reduced to 0.7 mm / s.

[0093] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 22 kHz. The ultrasonic amplitude is controlled at 9 μm.

[0094] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of four independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 20℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 15%; the water mist temperature of the final fourth spray section is 45℃.

[0095] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.3% (to prevent fracture of high-strength alloys).

[0096] Fine straightening stage: The profile is repeatedly bent and straightened in multiple passes (four passes) using multiple sets of staggered straightening rollers, with the relative bending deformation controlled at 0.5% in each pass. Finally, it is cut to length and subjected to T6 aging treatment (held at 120℃ for 24 hours) to obtain the finished aluminum profile.

[0097] The profile produced in this embodiment exhibits extremely high strength. Tests showed a yield strength of 510 MPa, a tensile strength of 570 MPa, and an elongation at break of 8%.

[0098] Example 6 This example provides a method for controlling the extrusion molding of aluminum profiles. The specific steps are as follows: S01. Obtain 1050 series pure aluminum billet, whose composition by mass percentage is: Si 0.10%, Fe 0.30%, Cu 0.02%, Mn 0.02%, Zr 0.05%, Mg 0.02%, Cr 0.01%, Zn 0.03%, Ti 0.02%, with the balance being Al. Perform homogenization heat treatment on the billet: hold at 600℃ for 2 hours, then cool with the furnace. Then heat it to the plastic temperature range of 500℃.

[0099] S02. The heated billet is placed into the billet holder of the extruder. The billet holder is equipped with three independently temperature-controlled electromagnetic heating zones along the extrusion direction. The temperature gradient is configured as follows: 400°C in the first zone at the feed end, 460°C in the second zone, and 500°C in the third zone at the discharge end.

[0100] S03. Start the extruder for staged extrusion: Initial low-speed extrusion stage: Use the first pressure (55% of the rated pressure) and control the extrusion speed at 0.5 mm / s.

[0101] Stable constant speed extrusion stage: The pressure is increased to the second pressure (80% of the rated pressure), and the extrusion speed is increased to 3.0 mm / s.

[0102] Final deceleration extrusion stage: The pressure is reduced to the third pressure (45% of the rated pressure), and the extrusion speed is reduced to 0.5 mm / s.

[0103] S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder at a frequency of 15 kHz. The ultrasonic amplitude is controlled at 8 μm.

[0104] S05. After the profile is extruded through the die, it immediately enters the quenching zone consisting of three independent spray sections for water mist cooling quenching. The cooling intensity gradually decreases along the extrusion direction: the first spray section has the largest water mist flow rate and the water temperature is 30℃; the flow rate of each subsequent section decreases progressively, with each section decreasing by 10%; the water mist temperature of the final third spray section is 60℃.

[0105] S06. Stretch and straighten the cooled profile: Pre-stretching stage: Apply a stretching rate of 0.3%.

[0106] Fine straightening stage: The profile is repeatedly bent and straightened by three sets of staggered straightening rollers, with the relative bending deformation controlled within 0.5%. Finally, it is cut to length and subjected to low-temperature stress-relieving annealing (150℃ for 1 hour) to obtain the finished aluminum profile.

[0107] The pure aluminum round bar obtained in this embodiment has a bright surface and good straightness. Tests showed that its yield strength was 35 MPa, tensile strength was 85 MPa, and elongation at break was 35%.

[0108] Comparative Example 1 This comparative example uses a traditional extrusion process, and the specific steps are as follows: S01. Obtain 6061 aluminum alloy billet with the same composition and state as in Example 1, and heat it to 480°C. Use constant extrusion process parameters: pressure is 80% of the rated pressure, and speed is constant at 5 mm / s. S02. Use a single-zone constant-temperature (480°C) billet container. S03. Start the extruder for constant-pressure and constant-speed extrusion, without staged control. S04. Do not apply any ultrasonic vibration. S05. After extrusion, directly immerse the profile in a high-pressure circulating water bath (water temperature 25°C) for uniform quenching. S06. Perform a large-deformation tensile straightening (2% elongation) on the profile, then saw it and age it.

[0109] The resulting profile has obvious friction scratches and striations on its surface, and a tail-reduction defect of approximately 120mm in length appears at the end. The cross-sectional dimensions are uneven, with deviations exceeding the tolerance by approximately 0.15mm at the thin-walled sections. The yield strength is 265 MPa, and the elongation at break is 9%.

[0110] Comparative Example 2 The only difference between this comparative example and Example 1 is the cooling method in step S05: After the profile is extruded through the die, it is quenched in a strong and uniform immersion water bath at a constant water temperature of 25°C without any gradient change. The remaining steps S01-S04 and S06 are exactly the same as in Example 1.

[0111] The surface quality of the resulting profile was similar to that of Example 1. However, the profile exhibited significant arc bending, with a straightness of 3.2 mm / m. Residual stress testing revealed that its internal longitudinal residual stress level was approximately 45% higher than that of the product in Example 1. After a week of subsequent storage, slight shape rebound deformation occurred.

[0112] Comparative Example 3 The only difference between this comparative example and Example 2 is the equipment structure of the ultrasonic vibration system: S04. Throughout the extrusion process, radial ultrasonic vibration is applied to the billet cylinder with the same parameters as in Example 2 (16 kHz, 10 μm). However, the billet cylinder used does not have a resonant cavity, and the ultrasonic transducer is directly coupled to the cylinder wall.

[0113] The surface quality of the resulting profile was improved compared to Comparative Example 1, but not as smooth as in Example 2, and still showed slight friction marks. During the actual extrusion process, the equipment displayed the same input power, but the actual vibration energy acting on the billet was weaker, and the extrusion pressure was approximately 10% higher than in Example 2. The yield strength of the profile was 278 MPa.

[0114] Comparative Example 4 The only difference between this comparative example and Example 1 is that the billet composition does not contain Zr: S01. Obtain a 6061 series aluminum alloy billet with the following composition by mass percentage: Si 0.6%, Mg 0.9%, Fe 0.25%, Cu 0.05%, Mn 0.10%, Cr 0.02%, Zn 0.05%, Ti 0.03%, excluding Zr, with the balance being Al and unavoidable impurities. The heat treatment and subsequent heating processes are the same as in Example 1. The preset extrusion process parameters are the same as in Example 1. The remaining steps S02-S06 are exactly the same as in Example 1.

[0115] The resulting product profile had acceptable appearance and dimensional accuracy, but its surface finish was slightly inferior to that of Example 1. Testing showed its yield strength to be 282 MPa, approximately 13 MPa lower than that of Example 1. Microstructural analysis revealed that the average size of its dynamically recrystallized grains was approximately 25 μm, significantly larger than that of Example 1 (approximately 18 μm).

[0116] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for controlling the extrusion molding of aluminum profiles, characterized in that, Includes the following steps: S01. Obtain aluminum profile blanks and perform homogenization heat treatment on them to bring them to the plastic temperature range. Determine the extrusion process parameters according to the cross-sectional shape and size specifications of the target profile. The components of the aluminum profile blanks, by mass percentage, include: Si 0.4-0.8%, Mg 0.6-1.2%, Zr 0.05-0.25%, Fe ≤ 0.35%, Cu ≤ 0.10%, Mn ≤ 0.15%, Cr ≤ 0.05%, Zn ≤ 0.10%, Ti 0.01-0.05%, with the balance being Al and unavoidable impurities. S02. The billet is placed into the billet cylinder of the extruder. The billet cylinder is provided with at least three independently temperature-controlled heating zones along the extrusion direction. The temperature of each heating zone increases in a gradient from the feed end to the discharge end. S03. Start the extruder and extrude the billet in stages. In the initial stage, the first pressure is used for low-speed extrusion. In the stable stage, the pressure is increased to the second pressure for constant-speed extrusion. In the final stage, the pressure is reduced to the third pressure for deceleration extrusion. S04. During the staged extrusion process, ultrasonic vibration is applied to the billet cylinder. The direction of the ultrasonic vibration is radial to the billet cylinder, the vibration frequency is 15-22kHz, and the amplitude of the ultrasonic vibration is related to the extrusion speed: when the extrusion speed is 3-5mm / s, the ultrasonic amplitude is 8-12μm; when the extrusion speed is greater than 5mm / s, the ultrasonic amplitude is 12-18μm. S05. After the profile is extruded, it is subjected to water mist cooling quenching, and the cooling intensity gradually decreases along the extrusion direction. S06. After cooling, the profile is stretched, straightened, cut to length, and aged to obtain the finished aluminum profile. The extruder ingot cylinder includes a cylinder body and an electromagnetic heating coil arranged sequentially from the inside to the outside. Multiple independent electromagnetic heating coils divide the cylinder body into at least three independently temperature-controlled heating zones along the extrusion direction. Multiple sets of axially extending resonant cavities are uniformly opened circumferentially in the wall thickness direction of the cylinder body. The axial length of the resonant cavity is 1 / 4 or 1 / 2 of the wavelength of the ultrasonic treatment sound wave, and the thickness of the resonant cavity is 1 / 3 to 2 / 3 of the cylinder body wall thickness.

2. The method according to claim 1, characterized in that, In step S01, determining the extrusion process parameters based on the cross-sectional shape and size specifications of the target profile includes: for complex profiles with a wall thickness difference greater than 5mm or an asymmetrical cross-sectional shape, the first pressure is 60%-70% of the rated pressure of the extruder, the second pressure is 85%-95%, and the third pressure is 40%-50%; for symmetrical profiles with uniform wall thickness, the first pressure is 55%-65% of the rated pressure, the second pressure is 80%-90%, and the third pressure is 45%-55%.

3. The method according to claim 1, characterized in that, In step S02, the temperature gradient configuration of the heating zone of the billet cylinder includes: the temperature of the first zone at the feeding end is 400±10℃, and the temperature of the last zone at the discharging end is the upper limit of the target plastic temperature of the billet.

4. The method according to claim 1, characterized in that, In step S03, in the initial stage, the extrusion speed of low-speed extrusion is 0.5-2 mm / s; in the stable stage, the extrusion speed of constant-speed extrusion is 3-8 mm / s; and in the final stage, the extrusion speed of deceleration extrusion is 0.5-1.5 mm / s.

5. The method according to claim 1, characterized in that, In step S05, the water mist cooling quenching is carried out in a quenching zone composed of multiple independent spray sections. Along the extrusion direction, the cooling water mist flow rate of the first spray section is the largest, and the flow rate of each subsequent section decreases progressively, with each section decreasing by 10%-20%. The water mist temperature of the first spray section is not higher than 30°C, and the water mist temperature of the final spray section is not higher than 60°C.

6. The method according to claim 1, characterized in that, In step S06, the stretching and straightening includes a pre-stretching stage and a fine straightening stage: the pre-stretching stage applies a stretching rate of 0.3%-0.8%; the fine straightening stage uses multiple sets of staggered straightening rollers to perform multiple passes of repeated bending and straightening on the profile, with the relative bending deformation of each pass controlled within the range of 0.5%-1.5%.

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