Extrusion forming control method of automobile luggage rack profile and automobile luggage rack profile

Abstract

The invention relates to the field of aluminum alloy extrusion control, and provides an automobile luggage rack profile extrusion forming control method and an automobile luggage rack profile. Mold cavity structure parameters, profile section function partition parameters and historical normal batch process data are obtained; the radial preheating zone temperature reference values of different radial positions of the bar, the axial heating zone temperature reference values of different axial positions and the initial extrusion speed are determined, the position, close to the surface layer, of the bar in the radial direction corresponds to the higher preheating temperature, the bar is used for extruding a thick-wall area of a profile, the position close to the core part is lower in temperature, and the bar is used for extruding a thin-wall area; collecting radial and axial actual temperatures in real time in the extrusion process and the metal flow velocity of a discharge port corresponding to each section function zone, calculating the difference value of the maximum flow velocity and the minimum flow velocity, namely the discharge flow velocity difference extreme value, and if the difference value is between a first threshold value and a second threshold value, adjusting the preheating temperature of the corresponding zone and reducing the extrusion speed; effective quality control of the thick and thin wall area of the luggage rack profile can be achieved.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy extrusion control technology, and more specifically, to an extrusion molding control method for automotive roof rack profiles and automotive roof rack profiles. Background Technology

[0002] Car roof rack profiles typically contain both thin-walled and thick-walled regions. Current technology primarily utilizes extrusion molding to manufacture car roof racks. This involves applying external force to a bar stock through an extrusion die, causing it to flow through the die's forming cavity to obtain a roof rack profile with the corresponding cross-sectional shape. The extrusion die is a core component in this process; its cavity structure and flow channel design directly determine the dimensional accuracy and appearance quality of the extruded profile. Existing conventional extrusion dies are generally capable of meeting the forming requirements for profiles with uniform wall thickness and have therefore been widely used in the mass production of various aluminum and alloy profiles for a long time.

[0003] In existing roof rack profile extrusion processes, the overall preheating temperature of the bar stock is often kept constant. Due to differences in metal flow resistance across different wall thicknesses, the billet flow rate in thin-walled areas may be significantly lower than in thick-walled areas. This can lead to incomplete filling and insufficient thickness in both thin-walled and thick-walled areas, or overfilling in thick-walled areas resulting in surface bulges and dimensional defects. Furthermore, the different cooling and shrinkage rates of thin-walled and thick-walled areas, when using the same preheating temperature, can cause uneven internal stress distribution after demolding, leading to overall warping and deformation of the profile, severely impacting the structural strength and assembly accuracy of the car roof rack. Therefore, existing extrusion dies cannot effectively control the quality of both thin-walled and thick-walled areas of the car roof rack profile. Summary of the Invention

[0004] The purpose of this application is to provide a method for controlling the extrusion molding of automotive roof rack profiles and the automotive roof rack profile itself. This method solves the technical problem that existing extrusion dies cannot effectively control the quality of thin-walled and thick-walled areas of automotive roof rack profiles, and achieves the technical effect of effectively controlling the quality of both thin-walled and thick-walled areas of automotive roof rack profiles.

[0005] In a first aspect, embodiments of this application provide a method for controlling the extrusion molding of automotive roof rack profiles. The method includes: acquiring mold cavity structure parameters, profile cross-sectional functional zoning parameters, and historical normal batch process data; determining, based on the mold cavity structure parameters, multiple profile cross-sectional functional zoning parameters, and historical normal batch process data, the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed of the bar stock at different radial positions; and before feeding the bar stock, starting the preheating system and the extrusion feeding mechanism based on the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed at different axial positions. The multiple profile cross-sectional functional zoning includes thin-walled and thick-walled regions. A higher preheating zone temperature reference value corresponds to a position of the bar stock radially closer to the surface, a position of the bar stock radially closer to the bar stock surface is used for extruding and molding the thick-walled section of the profile, and a position of the bar stock radially closer to the core corresponds to a lower temperature reference value. The preheating zone temperature reference value is used for the extrusion molding of thin-walled sections of the profile at the radial position of the bar stock near the core. During extrusion, the actual temperature of the radial preheating zone at different radial positions and the actual temperature of the axial heating zone at different axial positions of the bar stock are obtained. The metal flow velocities of multiple outlets corresponding to multiple functional zones of the profile section are obtained, and the maximum and minimum flow velocities among the multiple outlet metal flow velocities are determined. The difference between the maximum and minimum flow velocities is determined as the extreme value of the discharge flow rate difference. When the extreme value of the discharge flow rate difference is less than the first extreme value of the flow rate difference, the radial preheating zone temperature reference value at different radial positions remains unchanged. When the extreme value of the discharge flow rate difference is greater than the first extreme value of the flow rate difference and less than the second extreme value of the flow rate difference, the first temperature increment and the first extrusion speed reduction are obtained. Low flow rate section regions and high flow rate section regions are determined. The first temperature increment is increased in the radial preheating zone corresponding to the low flow rate section region, and the first temperature increment is decreased in the radial preheating zone corresponding to the high flow rate section region. The first extrusion speed reduction is decreased.

[0006] In one possible implementation, determining the low-velocity cross-sectional region and the high-velocity cross-sectional region includes: obtaining the thick-walled cross-sectional area and the bar cross-sectional area corresponding to the thick-walled section; determining the preheating zone factor of the thick-walled cross-sectional area and the bar cross-sectional area corresponding to the thick-walled section; determining the product of the bar radius and the preheating zone factor as the high-velocity cross-sectional radius; determining the annular region corresponding to the high-velocity cross-sectional radius from the surface of the bar to the center of the bar as the high-velocity cross-sectional region; and determining the region of the bar cross-section other than the high-velocity cross-sectional region as the low-velocity cross-sectional region.

[0007] In another possible implementation, the method further includes: increasing the temperature increment of the radial preheating zone corresponding to the low flow rate section region, decreasing the temperature increment of the radial preheating zone corresponding to the high flow rate section region, and decreasing the extrusion speed by a first extrusion speed reduction, and then obtaining the adjusted extreme value of the adjusted discharge flow rate difference; when the extreme value of the adjusted discharge flow rate difference is greater than the first extreme value of the flow rate difference and less than the second extreme value of the flow rate difference, increasing the preset preheating zone factor of the preheating zone factor to obtain the adjusted preheating zone factor; redetermining the low flow rate section region and the high flow rate section region based on the adjusted preheating zone factor; increasing the temperature increment of the radial preheating zone corresponding to the low flow rate section region, decreasing the temperature increment of the radial preheating zone corresponding to the high flow rate section region, and decreasing the extrusion speed by a first extrusion speed reduction.

[0008] In another possible implementation, the method further includes: obtaining a supplementary preheating power factor and a supplementary preheating time factor; obtaining the preheating power of the radial preheating zone corresponding to the high flow rate section region as the initial preheating power; obtaining the preheating time of the radial preheating zone corresponding to the high flow rate section region as the initial preheating time; determining the product of the supplementary preheating power factor and the initial preheating power as the supplementary preheating power; determining the product of the supplementary preheating time factor and the initial preheating time as the supplementary preheating time; when the adjusted discharge flow rate difference extreme value is greater than the first flow rate difference extreme value and less than the second flow rate difference extreme value, supplementary preheating is performed on the radial preheating zone corresponding to the high flow rate section region according to the supplementary preheating power and the supplementary preheating time to improve the surface fluidity of the high flow rate section region.

[0009] In another possible implementation, the method further includes: when supplementing preheating the radial preheating zone corresponding to the high flow rate section region according to the supplementary preheating power and supplementary preheating time, the extrusion speed at different stages is simultaneously reduced by the supplementary extrusion speed reduction.

[0010] In another possible implementation, the method further includes: supplementing the preheating power factor to 1.2 to 1.5; supplementing the preheating time factor to 0.1 to 0.2; and supplementing the extrusion speed reduction to 0.05 to 0.1.

[0011] In another possible implementation, the method further includes: when the extreme value of the discharge flow rate difference is greater than the extreme value of the second flow rate difference, obtaining a second temperature increment and a second extrusion speed reduction; determining a low flow rate section region and a high flow rate section region, increasing the second temperature increment for the radial preheating zone corresponding to the low flow rate section region, decreasing the second temperature increment for the radial preheating zone corresponding to the high flow rate section region, and simultaneously decreasing the second extrusion speed reduction until the extreme value of the discharge flow rate difference falls back to less than the extreme value of the first flow rate difference; wherein, the second temperature increment is greater than the first temperature increment, and the second extrusion speed reduction is greater than the first extrusion speed reduction.

[0012] In another possible implementation, the method further includes: determining the difference between the metal flow rates at multiple outlets at adjacent times as the absolute flow rate difference; determining the difference between the metal flow rates at multiple outlets and the metal flow rate reference value as the reference flow rate difference; when the absolute flow rate difference is greater than the preset absolute flow rate difference, or when the reference flow rate difference is greater than the preset reference flow rate difference, simultaneously increasing the first temperature reference value for the radial preheating zone temperature reference value of the bar stock at different radial positions, and decreasing the second temperature reference value for the axial heating zone temperature reference value at different axial positions.

[0013] In another possible implementation, the method further includes: simultaneously increasing the first temperature reference value of the radial preheating zone temperature reference value of the bar stock at different radial positions, and decreasing the second temperature reference value of the axial heating zone temperature reference value at different axial positions; after reducing the extrusion speed by the first extrusion speed reduction, obtaining the absolute difference in flow rate as the adjusted absolute difference in flow rate, and obtaining the reference flow rate difference as the adjusted reference flow rate difference; when the adjusted absolute difference in flow rate is greater than the preset absolute difference in flow rate, or when the adjusted reference flow rate difference is greater than the preset reference flow rate difference, increasing the initial extrusion speed by the preset initial extrusion speed.

[0014] Secondly, embodiments of this application provide a car roof rack profile, manufactured using the aforementioned extrusion molding control method for car roof rack profiles.

[0015] The beneficial effects of the embodiments in this application compared with the prior art are:

[0016] This application provides a method for controlling the extrusion molding of automotive roof rack profiles. The method includes: determining the baseline temperature values ​​of the radial preheating zone at different radial positions of the bar stock, the baseline temperature values ​​of the axial heating zone at different axial positions of the bar stock, and the initial extrusion speed; during the extrusion process, acquiring the actual temperature of the radial preheating zone at different radial positions of the bar stock and the actual temperature of the axial heating zone at different axial positions of the bar stock; acquiring the metal flow velocities of multiple outlets corresponding to multiple functional zones of the profile cross-section, and determining the maximum and minimum flow velocities among the multiple outlet metal flow velocities; determining the difference between the maximum and minimum flow velocities as the extreme value of the outlet flow rate difference; when the extreme value of the outlet flow rate difference is greater than the first extreme value of the flow rate difference and less than the second extreme value of the flow rate difference, acquiring the first temperature increment and the first extrusion speed reduction; determining the low flow rate cross-section region and the high flow rate cross-section region, increasing the first temperature increment in the radial preheating zone corresponding to the low flow rate cross-section region, decreasing the first temperature increment in the radial preheating zone corresponding to the high flow rate cross-section region, and decreasing the first extrusion speed reduction. In this embodiment, the temperature of the radial preheating zone at different radial positions can be controlled to improve the extrusion molding effect of the thin-walled and thick-walled areas of the car roof rack profile. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating the first method for controlling the extrusion molding of a car roof rack profile provided in this application embodiment;

[0019] Figure 2 A schematic diagram illustrating the workflow of the first extrusion molding control method for automobile roof rack profiles provided in this application embodiment;

[0020] Figure 3 A flowchart illustrating the extrusion molding control method for a second type of automotive roof rack profile provided in this application embodiment;

[0021] Figure 4 A schematic diagram illustrating the workflow of the second extrusion molding control method for automotive roof rack profiles provided in this application embodiment;

[0022] Figure 5 A flowchart illustrating the third method for controlling the extrusion molding of a car roof rack profile provided in this application embodiment;

[0023] Figure 6 A schematic diagram illustrating the workflow of the third method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment;

[0024] Figure 7 A flowchart illustrating the fourth method for controlling the extrusion molding of a car roof rack profile provided in this application embodiment;

[0025] Figure 8 A schematic diagram illustrating the workflow of the fourth method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment;

[0026] Figure 9 A flowchart illustrating the fifth method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment;

[0027] Figure 10 A schematic diagram of the workflow for the fifth extrusion molding control method for automobile roof rack profiles provided in this application embodiment;

[0028] Figure 11 This is a flowchart illustrating the sixth method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment. Detailed Implementation

[0029] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0030] It should be noted that when a component or structure is referred to as being "fixed to" or "set on" another component or structure, it can be directly on or indirectly on the other component or structure. When a component or structure is referred to as being "connected to" another component or structure, it can be directly connected to or indirectly connected to the other component or structure.

[0031] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device, component, or structure referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] Existing extrusion dies cannot achieve effective quality control for both thin-walled and thick-walled areas of automotive roof rack profiles.

[0034] Based on the above reasons, this application provides a method for controlling the extrusion molding of automotive roof rack profiles. The method includes: acquiring mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data; determining the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed of the bar stock at different radial positions based on the mold cavity structure parameters, multiple profile cross-section functional zoning parameters, and historical normal batch process data; before feeding the bar stock, starting the preheating system and extrusion feeding mechanism based on the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed; during the extrusion process, acquiring the actual temperature of the bar stock in the radial preheating zone at different radial positions, the actual temperature of the bar stock in the axial heating zone at different axial positions, and the initial extrusion speed. The actual temperature of the axial heating range at the location is measured; the metal flow rate of multiple outlets corresponding to multiple functional zones of the profile cross-section is obtained, and the maximum and minimum flow rates among the multiple outlet metal flow rates are determined; the difference between the maximum and minimum flow rates is determined as the extreme value of the outlet flow rate difference; when the extreme value of the outlet flow rate difference is less than the first extreme value of the flow rate difference, the baseline temperature value of the radial preheating zone at different radial positions remains unchanged; when the extreme value of the outlet flow rate difference is greater than the first extreme value of the flow rate difference and less than the second extreme value of the flow rate difference, a first temperature increment and a first extrusion speed reduction are obtained; low flow rate cross-section regions and high flow rate cross-section regions are determined, the first temperature increment is increased for the radial preheating zone corresponding to the low flow rate cross-section region, the first temperature increment is decreased for the radial preheating zone corresponding to the high flow rate cross-section region, and the first extrusion speed reduction is decreased. In this embodiment, the temperature of the radial preheating zone at different radial positions can be controlled to improve the extrusion molding effect of thin-walled and thick-walled regions of the automotive roof rack profile.

[0035] In some scenarios, the extrusion molding control method for car roof rack profiles according to the present application can be applied to the mass production of roof racks for family SUVs, precisely controlling the curvature and wall thickness uniformity of the profiles, reducing the defect rate in mass production, and adapting to the appearance assembly requirements of different models.

[0036] The following describes in detail, with specific examples, a method for controlling the extrusion molding of automotive roof rack profiles provided in this application.

[0037] Figure 1 A flowchart illustrating the first method for controlling the extrusion molding of a car roof rack profile provided in this application embodiment is shown below. Figure 1 As shown in the embodiment of this application, an extrusion molding control method for automobile roof rack profiles is provided. The method further includes steps S110 to S130, which will be described in detail below.

[0038] S110. Obtain the mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data. Based on the mold cavity structure parameters, multiple profile cross-section functional zoning parameters, and historical normal batch process data, determine the radial preheating zone temperature reference values ​​for the bar stock at different radial positions, the axial heating zone temperature reference values ​​for the bar stock at different axial positions, and the initial extrusion speed. Before feeding the bar stock, start the preheating system and extrusion feeding mechanism based on the radial preheating zone temperature reference values ​​for different radial positions, the axial heating zone temperature reference values ​​for different axial positions, and the initial extrusion speed. The multiple profile cross-section functional zoning includes thin-walled and thick-walled regions. The position of the bar stock radially closer to the surface corresponds to a higher preheating zone temperature reference value; the position of the bar stock radially closer to the surface is used for extruding and forming the thick-walled section of the profile; the position of the bar stock radially closer to the core corresponds to a lower preheating zone temperature reference value; and the position of the bar stock radially closer to the core is used for extruding and forming the thin-walled section of the profile.

[0039] Figure 2 A schematic diagram of the workflow for the extrusion molding control method of the first type of automobile roof rack profile provided in this application embodiment is shown below. Figure 2 As shown, in this implementation, the mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data can be obtained through the supporting process parameter acquisition terminal. The three types of parameters collected can be stored in the parameter database of the process control platform to provide data support for the determination of subsequent process benchmark values.

[0040] It should be noted that the mold cavity structure parameters are a set of parameters that describe the shape and size attributes of the mold forming cavity. Different parameters will directly affect the metal flow path and forming resistance during the bar extrusion process.

[0041] For example, the mold cavity structure parameters may include the overall forming length of the cavity, the radius of the cavity inlet fillet, the draft angle of the cavity, the surface roughness of the cavity, and the cross-sectional dimensions of the cavity outlet.

[0042] It should be noted that the functional zoning parameters of the profile section are parameters that characterize the functional requirements and forming requirements of different cross-sectional areas of the profile. The parameter differences in different areas determine the direction of preheating and extrusion process adjustment for the corresponding positions of the bar stock.

[0043] For example, the functional zoning parameters of the profile section may include the nominal thickness of each zone, the profile dimensions of each zone, the geometric tolerance requirements of each zone, the surface quality grade requirements of each zone, and the mechanical performance requirements of each zone.

[0044] It should be noted that the historical normal batch process data is the full-process process data recorded when producing qualified profiles in the past, which can provide a reference for determining the process parameters of the current batch.

[0045] For example, historical normal batch process data may include the preheating temperature range of bars of the same specification, the extrusion speed range of the same die, the process parameters corresponding to the forming qualification rate of the same type of profile, the equipment operation parameter records during the production process, and the process parameter thresholds corresponding to the finished product inspection qualification.

[0046] In this implementation, the parameter matching module of the process control platform can be invoked. Inputting mold cavity structure parameters, functional zone parameters for multiple profile sections, and historical normal batch process data, the module determines the radial preheating zone temperature reference values ​​for the bar stock at different radial positions, the axial heating zone temperature reference values ​​for the bar stock at different axial positions, and the initial extrusion speed through preset parameter matching logic. The determined reference values ​​and speed parameters can then be synchronized to the control units of the preheating system and the extrusion feeding mechanism, providing an operational basis for subsequent equipment startup.

[0047] It should be noted that the different radial positions of the bar stock are different regions divided outward from the core as the origin, according to the radial direction of the bar stock. The metal in different regions corresponds to different cross-sectional positions of the formed profile during extrusion, so different preheating temperatures are required.

[0048] For example, the bar stock can be divided into three radial regions based on its radius, with the center of the bar stock as the origin: the core region with a radius of 0 to 1 / 3 of the bar stock radius, the middle region with a radius of 1 / 3 to 2 / 3 of the bar stock radius, and the surface region with a radius of 2 / 3 to the outer edge of the bar stock.

[0049] It should be noted that the radial preheating zone temperature reference value is the standard preheating temperature value that needs to be achieved at different radial positions of the bar stock. The temperature setting needs to match the fluidity requirements of the bar stock at the corresponding position during forming.

[0050] For example, the temperature reference value of the radial preheating zone can be set to a range of 380 degrees Celsius to 520 degrees Celsius, wherein the temperature reference value for the core region is 380 degrees Celsius to 420 degrees Celsius, the temperature reference value for the middle region is 420 degrees Celsius to 470 degrees Celsius, and the temperature reference value for the surface region is 470 degrees Celsius to 520 degrees Celsius.

[0051] It should be noted that the different axial positions of the bar stock are defined according to the feeding direction of the bar stock, starting from the end face that first enters the die. The heating requirements of different regions are matched with the forming requirements of different stages in the extrusion process.

[0052] For example, the bar stock can be divided into three axial positions according to its length, starting from the feed end: the front end region from 0 to 1 / 4 of the bar stock length, the middle section region from 1 / 4 to 3 / 4 of the bar stock length, and the rear end region from 3 / 4 to the tail end of the bar stock.

[0053] It should be noted that the reference value for the axial heating range is the standard value of the temperature range that the bar stock needs to reach in the preheating stage at different axial positions. The temperature setting is adapted to the forming temperature requirements of different feeding stages in the extrusion process.

[0054] It should be noted that the initial extrusion speed is the standard feed speed when the bar stock first enters the die for extrusion. The speed setting needs to match the initial state of the bar stock and the initial resistance of the die forming to ensure the forming stability in the early stage of extrusion.

[0055] For example, the initial extrusion speed can be set to a range of 0.8 mm / s to 2.5 mm / s, wherein the initial extrusion speed range for profiles with a high proportion of thin walls is 0.8 mm / s to 1.5 mm / s, and the initial extrusion speed range for profiles with a high proportion of thick walls is 1.5 mm / s to 2.5 mm / s.

[0056] It should be noted that the empirical value table is a pre-compiled table of process baseline values ​​corresponding to different combinations of parameters. It is built based on a large amount of data from past production verification and can quickly complete the matching and determination of parameters.

[0057] For example, an empirical value table containing different mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data combinations can be pre-constructed. After inputting the three types of parameters for the current batch, the historical parameter combination with the highest similarity can be matched in the empirical value table, and the corresponding radial preheating zone temperature reference value, axial heating zone temperature reference value, and initial extrusion speed can be extracted as parameters for the current batch.

[0058] It should be noted that the thickness classification standard for thin-walled and thick-walled regions of profiles is a criterion for distinguishing the thickness attributes of different regions of the profile cross-section, and is set based on the overall thickness range and forming requirements of the profile.

[0059] For example, taking aluminum alloy profiles as an example, the area with a cross-sectional thickness of less than or equal to 2mm can be divided into the thin-walled area of ​​the profile, and the area with a cross-sectional thickness of greater than or equal to 5mm can be divided into the thick-walled area of ​​the profile. The area with a thickness between 2mm and 5mm can be assigned to the corresponding zone according to the mechanical performance requirements of the product.

[0060] In this implementation, before the bar stock is fed, the determined radial preheating zone temperature reference values ​​at different radial positions and the axial heating zone temperature reference values ​​at different axial positions are sent to the control terminal of the preheating system. The initial extrusion speed is also sent to the control terminal of the extrusion feeding mechanism, triggering the preheating system and the extrusion feeding mechanism to start operation according to the corresponding parameters. After the equipment starts, actual operating parameters can be collected in real time and compared with the reference values ​​to ensure the accuracy of process execution.

[0061] It should be noted that the specific radius range of the bar stock near the surface and near the core is a radial region range determined based on the overall radius of the bar stock, corresponding to different thickness cross-sectional areas of the formed profile.

[0062] For example, for a bar stock with a diameter of 120 mm, an annular region 0 mm to 20 mm from the outer edge of the bar stock can be defined as a radially upward position close to the surface, and a circular region 0 mm to 30 mm from the center of the bar stock can be defined as a radially upward position close to the core.

[0063] S120. During the extrusion process, obtain the actual temperature of the radial preheating zone of the bar stock at different radial positions and the actual temperature of the axial heating zone of the bar stock at different axial positions. Obtain the metal flow rate at multiple outlets corresponding to multiple profile cross-section functional zones, and determine the maximum and minimum flow rates among the multiple outlet metal flow rates. Determine the difference between the maximum and minimum flow rates as the extreme value of the outlet flow rate difference.

[0064] In this implementation, during the extrusion process, multiple temperature acquisition units pre-positioned in the preheating zone can collect the actual temperature of the bar stock in the radial preheating zone at different radial positions and the actual temperature of the bar stock in the axial heating zone at different axial positions. The collected actual temperature data can be uploaded to the process control platform in real time, providing real-time data support for the dynamic adjustment of subsequent process parameters.

[0065] It should be noted that the actual temperature of the radial preheating zone is the real-time temperature of the bar stock at different radial positions during the extrusion process. The data acquisition method needs to be adapted to the distribution characteristics of the radial region, and the numerical range needs to match the preheating reference value requirements of the corresponding radial region.

[0066] For example, embedded thermocouples can be arranged at different radial positions of the preheating equipment to collect the bar temperature at each radial position through a non-contact temperature sensing method. The actual temperature range of the radial preheating zone is 380 degrees Celsius to 520 degrees Celsius.

[0067] It should be noted that the actual temperature in the axial heating range is the real-time temperature of the bar stock at different axial positions during the extrusion process. The acquisition method needs to be adapted to the axial feeding characteristics of the bar stock, and the numerical range needs to match the heating reference value requirements of the corresponding axial region.

[0068] For example, infrared temperature sensors can be arranged at different nodes along the axial direction of the preheating equipment to collect the temperature of the bar at the corresponding axial position as the bar feed progresses. The actual temperature range of the axial heating range is 400 degrees Celsius to 550 degrees Celsius.

[0069] In this implementation, a flow rate detection device positioned on the mold's discharge side can collect the metal flow rates from multiple discharge ports corresponding to multiple functional zones of the profile cross-section. The collected metal flow rate data from each discharge port can be aggregated into a flow rate analysis module, where a preset numerical comparison logic determines the maximum and minimum flow rates among the multiple discharge ports. The determined maximum and minimum flow rates can then be stored in a process data record library, providing foundational data for subsequent flow rate difference calculations.

[0070] It should be noted that the multiple discharge ports corresponding to the multiple functional zones of the profile cross-section are the discharge channel positions set on the mold and the different functional zones of the profile, and their distribution corresponds one-to-one with the functional zone layout of the profile cross-section.

[0071] For example, the discharge port corresponding to the thin-walled area of ​​the profile can be located on the inner side of the discharge end of the mold cavity, and the discharge port corresponding to the thick-walled area of ​​the profile can be located on the outer side of the discharge end of the mold cavity, with the outline of each discharge port matching the cross-sectional outline of the corresponding functional area.

[0072] It should be noted that the discharge port metal flow rate is the real-time speed at which metal flows out of the corresponding discharge port during the extrusion process. The detection method needs to be adapted to the flow characteristics of high-temperature metal, and the value range needs to match the set range of the initial extrusion speed.

[0073] For example, the metal flow velocity at each outlet can be detected non-contactly using a laser Doppler velocimeter, with the metal flow velocity at the outlet ranging from 0.8 mm / s to 2.5 mm / s.

[0074] It should be noted that the specific rules for determining the maximum and minimum flow rates from multiple outlet metal flow rates are based on the execution logic of comparing multiple real-time flow rate data to ensure the accuracy of flow rate extreme value determination.

[0075] For example, all the metal flow rate data collected from the outlet within the same sampling period can be sorted in ascending order according to their numerical values, and the first value after sorting can be taken as the minimum flow rate, and the last value after sorting can be taken as the maximum flow rate.

[0076] In this implementation, the flow rate difference calculation module can be called, the determined maximum and minimum flow rates can be input into the calculation logic, the difference between the maximum and minimum flow rates can be obtained through difference calculation, and the difference can be determined as the extreme value of the discharge flow rate difference.

[0077] It should be noted that the extreme value of the discharge flow rate difference is the core indicator reflecting the uniformity of metal flow at each discharge port. Its calculation process is based on the extreme value of the flow rate at the same moment, and the common value range matches the complexity of the profile cross-section.

[0078] For example, the maximum flow rate of 2.1 mm / s detected at the same time point can be subtracted from the minimum flow rate of 1.2 mm / s to obtain the extreme value of the discharge flow rate difference of 0.9 mm / s. The common range of extreme values ​​of the discharge flow rate difference is 0.1 mm / s to 1.2 mm / s.

[0079] S130. When the extreme value of the discharge flow rate difference is less than the first extreme value of the flow rate difference, the baseline temperature value of the radial preheating zone at different radial positions remains unchanged. When the extreme value of the discharge flow rate difference is greater than the first extreme value of the flow rate difference but less than the second extreme value of the flow rate difference, the first temperature increment and the first extrusion speed reduction are obtained. Low-flow-rate cross-sectional areas and high-flow-rate cross-sectional areas are determined. For the radial preheating zone corresponding to the low-flow-rate cross-sectional area, the first temperature increment is increased; for the radial preheating zone corresponding to the high-flow-rate cross-sectional area, the first temperature increment is decreased; and for the extrusion speed, the first extrusion speed reduction is decreased.

[0080] In this implementation, the calculated extreme value of the discharge flow rate difference can be compared with a preset first extreme value of the flow rate difference. When the extreme value of the discharge flow rate difference is less than the first extreme value of the flow rate difference, a maintenance command can be sent to the control unit of the preheating system to keep the temperature reference value of the radial preheating zone at different radial positions unchanged. The current extreme value of the discharge flow rate difference and the temperature reference value can be recorded synchronously and stored in the process operation log.

[0081] For example, the numerical range of the first flow rate difference extreme value can be set from 0.1 mm / s to 0.3 mm / s. The setting basis can refer to the fluctuation range of the discharge flow rate difference of qualified batches of the same type of profile to ensure that the flow rate deviation will not affect the forming quality of the profile.

[0082] In this implementation, the extreme value of the discharge flow rate difference can be compared with a preset second extreme value. When the extreme value of the discharge flow rate difference is greater than the first extreme value but less than the second extreme value, the process parameter adjustment library can be called to obtain the first temperature increment and the first extrusion speed reduction that match the current operating conditions. The obtained adjustment parameters can be synchronized to the parameter adjustment execution module to provide a basis for subsequent temperature and speed adjustments.

[0083] For example, the numerical range of the second flow rate difference extreme value can be set from 0.8 mm / s to 1.2 mm / s. The setting basis can refer to the critical value of the flow rate difference corresponding to the forming defects that occur during the bar extrusion process, so as to avoid the profile being unqualified due to excessive flow rate deviation.

[0084] It should be noted that the first temperature increment is the single adjustment step size when adjusting the temperature of the radial preheating zone. Its value range needs to be adapted to the temperature sensitivity of the bar stock to avoid excessive temperature adjustment that could cause drastic changes in the metal flow characteristics.

[0085] For example, the numerical range of the first temperature increment can be set to 5 degrees Celsius to 15 degrees Celsius, and the specific value can be determined according to the material properties of the current bar stock and the range of the preheating temperature reference value.

[0086] It should be noted that the first reduction in extrusion speed is the single adjustment range when adjusting the extrusion speed. Its value range needs to be adapted to the operating characteristics of the extrusion feed mechanism to avoid excessive speed adjustment range affecting the stability of the extrusion process.

[0087] For example, the numerical range of the first extrusion speed reduction can be set from 0.1 mm / s to 0.3 mm / s, and the specific value can be determined according to the magnitude of the current initial extrusion speed and the complexity of the profile cross-section.

[0088] In this implementation, low-velocity and high-velocity cross-sectional areas can be determined based on the metal flow rate detection results at each discharge port using a preset partitioning logic. The radial preheating zones corresponding to the two types of areas can be matched according to a pre-established mapping relationship between the cross-sectional areas and the radial preheating zones. A temperature adjustment command can be sent to the preheating system to increase the first temperature increment in the radial preheating zone corresponding to the low-velocity cross-sectional area and decrease the first temperature increment in the radial preheating zone corresponding to the high-velocity cross-sectional area. A speed adjustment command can be sent to the extrusion feed mechanism to decrease the first extrusion speed reduction.

[0089] For example, the thick-walled region of the profile corresponds to the high-flow-rate section region, which can be mapped to the radial preheating zone near the surface of the bar stock. The bar stock metal in this zone fills the forming position of the thick-walled region of the profile during extrusion.

[0090] It should be noted that the mapping relationship between the high flow velocity section region and the corresponding radial preheating zone is a pre-established correspondence between the section region and the radial preheating zone of the bar stock, determined based on the path matching relationship of metal extrusion flow.

[0091] For example, the thick-walled region of the profile corresponds to the high-flow-rate section region, which can be mapped to the radial preheating zone near the core of the bar stock in the radial direction. The bar stock metal in this region fills the forming position of the thick-walled region of the profile stock during extrusion.

[0092] It should be noted that the operation of increasing the first temperature increment in the radial preheating zone corresponding to the low flow rate section is a process of adjusting the temperature reference value of the corresponding preheating zone based on the mapping relationship, which is used to improve the metal flowability of the bar stock at the corresponding position.

[0093] For example, if the current temperature reference value of the radial preheating zone corresponding to the low flow rate section is 470 degrees Celsius and the first temperature increment is 10 degrees Celsius, the temperature reference value of the radial preheating zone can be adjusted to 480 degrees Celsius, and the preheating system can be controlled to operate according to the adjusted temperature reference value.

[0094] It should be noted that the operation of reducing the first temperature increment of the radial preheating zone temperature corresponding to the low flow rate section region is a process of adjusting the temperature reference value of the corresponding preheating zone based on the mapping relationship, which is used to reduce the metal flowability of the bar stock at the corresponding position.

[0095] For example, if the current temperature reference value of the radial preheating zone corresponding to the low flow rate section is 400 degrees Celsius and the first temperature increment is 10 degrees Celsius, the temperature reference value of the radial preheating zone can be lowered to 390 degrees Celsius, and the preheating system can be controlled to operate according to the adjusted temperature reference value.

[0096] It should be noted that the thick-walled area of ​​the profile corresponds to the high-flow-rate section area, which can be mapped to the radial preheating zone near the surface of the bar stock. The bar stock can be preheated by a ring coil. Due to the skin effect of the eddy current effect, by reasonably controlling the preheating temperature and preheating power, a higher preheating temperature can be ensured for the thick-walled area of ​​the profile stock surface.

[0097] It should be noted that the thin-walled area of ​​the profile corresponds to the low flow velocity section area, which can be mapped to the radial preheating zone near the core of the bar stock. The bar stock can be preheated by a ring coil. Due to the skin effect of the eddy current effect, by reasonably controlling the preheating temperature and preheating power, the preheating temperature of the thick-walled area of ​​the profile core of the bar stock can be kept lower.

[0098] It should be noted that reducing the extrusion speed by the first extrusion speed reduction is a process of lowering the operating speed of the extrusion feed mechanism, which is used to slow down the overall metal flow speed and reduce the flow speed difference in different areas.

[0099] For example, if the current extrusion speed is 2.0 mm / s and the first extrusion speed reduction is 0.2 mm / s, the operating speed of the extrusion feed mechanism can be reduced to 1.8 mm / s, and the extrusion feed mechanism can be controlled to run at the adjusted speed.

[0100] This method first determines the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed at different radial positions of the bar stock based on the mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data. Then, the preheating system and extrusion feeding mechanism are started accordingly. The area with higher radial surface temperature corresponds to the thick-walled section of the extruded profile, while the area with lower core temperature corresponds to the thin-walled section of the extruded profile. This method can match the different metal flow rate requirements for forming different wall thickness areas of automotive roof rack profiles.

[0101] This method allows for real-time acquisition of the actual temperature of the radial preheating zone at different radial positions and the actual temperature of the axial heating zone at different axial positions of the bar stock during the extrusion process. Simultaneously, it acquires the metal flow velocity at the discharge port corresponding to multiple functional zones of the profile cross-section. The difference between the maximum and minimum flow velocities is calculated as the extreme value of the discharge flow velocity difference, which can accurately capture the problem of uneven flow velocity during the extrusion process and provide an accurate basis for subsequent parameter adjustments.

[0102] This implementation maintains the radial preheating zone temperature baseline value unchanged when the extreme value of the discharge flow rate difference is less than the first extreme value of the flow rate difference. When the extreme value of the discharge flow rate difference is between the first and second extreme values ​​of the flow rate difference, the first temperature increment is increased in the radial preheating zone corresponding to the low flow rate section area, and the first temperature increment is decreased in the radial preheating zone corresponding to the high flow rate section area. At the same time, the extrusion speed is reduced by the first extrusion speed reduction. This can dynamically balance the discharge flow rate of each section, reduce the forming defects of the automotive roof rack profile, and improve the yield of profile forming.

[0103] Figure 3 A flowchart illustrating the extrusion molding control method for a second type of automotive roof rack profile provided in this application embodiment is shown below. Figure 3 As shown, in some implementations, in the above-mentioned S130, the determination of the low velocity cross-section region and the high velocity cross-section region also includes S131 to S132, which will be specifically explained below.

[0104] S131. Obtain the thick-walled cross-sectional area and bar cross-sectional area corresponding to the thick-walled section. Determine the preheating zone factor for the thick-walled cross-sectional area and bar cross-sectional area corresponding to the thick-walled section. Determine the product of the bar radius and the preheating zone factor as the high-velocity section radius.

[0105] Figure 4 A schematic diagram of the workflow for the extrusion molding control method of the second type of automobile roof rack profile provided in this application embodiment is shown below. Figure 4 As shown, in this implementation, the cross-sectional contour data of the thick-walled region of the profile can be extracted using a 3D modeling tool, and the corresponding thick-walled cross-sectional area can be calculated. The specification parameter database of the bar stock can be accessed to match the cross-sectional area of ​​the current batch of bar stock. Both types of area data can be synchronized to the process calculation module, providing basic data for the subsequent calculation of the preheating zone factor.

[0106] It should be noted that the thick-walled cross-sectional area is the projected area of ​​the thick-walled region of the profile. The calculation method is based on the outline dimensions of the thick-walled region, and the numerical range matches the overall specifications of the profile and the proportion of the thick-walled region.

[0107] For example, the outline of the region with a thickness of 5 mm or more in the profile section can be identified by 3D modeling software, and the thick-walled cross-sectional area can be obtained by calling the software's built-in area calculation function. The value range of the thick-walled cross-sectional area is 300 square millimeters to 2000 square millimeters.

[0108] It should be noted that the cross-sectional area of ​​the bar stock is the cross-sectional area of ​​the bar stock currently in use. The value is based on the nominal diameter parameter of the bar stock, and the common value range is matched with the processing capacity of the extrusion equipment.

[0109] For example, the cross-sectional area of ​​the bar stock can be calculated using the formula for calculating the area of ​​a circle, based on the nominal diameter parameter of the bar stock. The common range of values ​​for the cross-sectional area of ​​the bar stock is 7,000 square millimeters to 13,000 square millimeters.

[0110] In this implementation, the preheating zone factor calculation logic can be invoked, taking into account the thick-walled cross-sectional area and the bar cross-sectional area corresponding to the thick-walled section. The preheating zone factor is then determined according to preset calculation rules. The obtained preheating zone factor can be stored in the process parameter library, providing intermediate parameters for subsequent calculations of high-flow-rate cross-sectional radii.

[0111] It should be noted that the preheating zone factor is a parameter that reflects the proportion of the thick-walled region to the overall cross-section of the bar stock. It is obtained by calculating the cross-sectional area of ​​the thick-walled region and the cross-sectional area of ​​the bar stock, and is used to determine the radial boundary of the corresponding high-velocity region in the bar stock.

[0112] For example, the specific formula for calculating the preheating zone factor can be: preheating zone factor = 1 - (thick wall cross-sectional area / bar cross-sectional area). If the thick wall cross-sectional area is 1200 square millimeters and the bar cross-sectional area is 10000 square millimeters, the calculated preheating zone factor is 0.88.

[0113] It should be noted that the numerical range of the preheating zone factor is determined by the ratio of the thick-wall cross-sectional area to the cross-sectional area of ​​the bar stock. Different profiles with different thick-wall ratios correspond to different preheating zone factor values.

[0114] For example, the common value range of the preheating zone factor is 0.6 to 0.95. When the proportion of the thick wall area of ​​the profile is larger, the value of the preheating zone factor is smaller; when the proportion of the thick wall area of ​​the profile is smaller, the value of the preheating zone factor is larger.

[0115] In this implementation, the specification parameters of the current batch of bar stock can be retrieved to obtain the corresponding bar stock radius. The high-velocity section radius calculation logic can be invoked, taking the bar stock radius and preheating zone factor as input, and multiplying them to obtain their product, which is then determined as the high-velocity section radius. The obtained high-velocity section radius can be synchronized to the control unit of the preheating system, providing boundary parameters for the division of the radial preheating zone.

[0116] It should be noted that the bar radius is the cross-sectional radius of the bar currently in use, and the value is based on the nominal diameter parameter of the bar, with common value ranges and matching the clamping specifications of the extrusion equipment.

[0117] For example, the nominal diameter of the bar stock can be taken as half as the bar stock radius, and the common value range of bar stock radius is 30 mm to 80 mm.

[0118] It should be noted that the high-velocity section radius is the radial boundary radius of the corresponding high-velocity region in the bar stock. It is calculated by multiplying the bar stock radius and the preheating zone factor, and is used to distinguish between the high-velocity region and the low-velocity region in the radial direction of the bar stock.

[0119] For example, if the bar stock radius is 50 mm and the preheating zone factor is 0.88, the high-velocity section radius is 44 mm by multiplying 50 mm by 0.88. That is, the region in the bar stock with a radius less than or equal to 44 mm is the radial region corresponding to the high-velocity section.

[0120] For example, the common numerical range of the high flow rate section radius is 20 mm to 70 mm. The area inside the bar stock corresponding to this radius corresponds to the thin-walled area of ​​the formed profile during extrusion, which is usually the radial area corresponding to the high flow rate section.

[0121] S132. Determine the annular region corresponding to the radius of the high-velocity section from the surface of the bar stock to the center of the bar stock, as the high-velocity section region. Determine the region of the bar stock cross-section other than the high-velocity section region, as the low-velocity section region.

[0122] In this implementation, the pre-calculated high-velocity section radius parameters can be retrieved. Combined with the radial distribution characteristics of the bar stock, a ring-shaped region corresponding to the high-velocity section radius from the bar stock surface to the center is determined and marked as the high-velocity section region. The boundary parameters of the high-velocity section region can be synchronized to the preheating system control unit, providing a locational basis for setting the preheating temperature of this region.

[0123] It should be noted that the annular region corresponding to the high-velocity section radius from the surface of the bar stock to the center of the bar stock is a radial region defined based on the numerical relationship between the radial coordinates of the bar stock and the high-velocity section radius, corresponding to the part of the bar stock with a higher metal flow rate during the extrusion process.

[0124] For example, if the bar stock radius is 50 mm and the high-velocity section radius is 20 mm, the annular region with radial coordinates between 20 mm and 50 mm can be defined as the corresponding annular region, which is the annular portion of the bar stock near the surface.

[0125] It should be noted that the common range of the high flow velocity section region is determined by the combined values ​​of the overall radius of the bar stock and the radius of the high flow velocity section. Different profile structures and bar stock specifications correspond to different ranges.

[0126] For example, a common range of high flow rate section regions is an annular region extending 10 mm to 30 mm inward from the surface of the bar stock. During extrusion, the bar stock metal in this region typically corresponds to the thick-walled section of the filler profile, and the flow rate is relatively high to form the thicker area of ​​the profile.

[0127] In this implementation, after dividing the high-velocity section region, the remaining area of ​​the bar stock cross-section can be defined to identify the area outside the high-velocity section region, which is then marked as the low-velocity section region. The boundary parameters of the low-velocity section region can be synchronized to the preheating system control unit, providing a location basis for setting the preheating temperature of this region.

[0128] For example, if the bar stock radius is 50 mm and the high flow rate section region is an annular region with a radial coordinate of 44 mm to 50 mm, the circular region with a radial coordinate of less than or equal to 44 mm can be defined as the low flow rate section region, which is the part of the bar stock near the core.

[0129] For example, a common range of low flow rate section regions is a circular area extending outward from the bar core to a distance of 10 mm to 30 mm from the surface. During extrusion, the bar metal in this region typically corresponds to the thin-walled section of the filling profile, and the flow rate is relatively low to form the thinner area of ​​the profile.

[0130] This implementation method obtains the thick-walled cross-sectional area and bar cross-sectional area corresponding to the thick-walled section, calculates the preheating zone factor of the two, and then determines the high-velocity section radius by multiplying the bar radius and the preheating zone factor. This can accurately delineate the velocity-related region boundary and avoid subjective errors in region division.

[0131] By using this method, the annular region corresponding to the radius of the high-flow-rate section from the surface of the bar stock is defined as the high-flow-rate section region. This can directly correspond to the forming feed position of the thick-walled section of the profile, match the feed flow characteristics during the forming of the thick-walled region, and reduce the matching error of subsequent temperature adjustment.

[0132] This implementation method defines the portion of the bar stock cross-section other than the high-velocity section region as the low-velocity section region, which corresponds to the forming feed position of the thin-walled section, achieving a clear division of different flow rate regions and providing an accurate target for subsequent zoned temperature adjustment.

[0133] Figure 5 A flowchart illustrating the third method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment is shown below. Figure 5 As shown, in some implementations, the above method also includes S140 to S150, which will be described in detail below.

[0134] S140. Increase the first temperature increment in the radial preheating zone corresponding to the low flow rate section area, decrease the first temperature increment in the radial preheating zone corresponding to the high flow rate section area, and decrease the first extrusion speed reduction in the extrusion speed to obtain the extreme value of the adjusted discharge flow rate difference.

[0135] Figure 6 A schematic diagram of the workflow for the extrusion molding control method of the third type of automobile roof rack profile provided in this application embodiment is shown below. Figure 6 As shown, in this implementation, after adjusting the temperature of the radial preheating zone corresponding to the low flow rate section, lowering the temperature of the radial preheating zone corresponding to the high flow rate section, and lowering the extrusion speed, a preset process stabilization period can be waited for to ensure that the effects of temperature and speed adjustments are transmitted to the discharge end. The metal flow rate at each discharge port can be re-acquired using a flow rate detection device, and the adjusted discharge flow rate difference extreme value can be calculated. This adjusted discharge flow rate difference extreme value can be synchronized to the process analysis module for evaluating the effect of this parameter adjustment.

[0136] It should be noted that the adjusted radial preheating zone temperature is the actual operating temperature of each radial preheating zone after the parameter adjustment is completed. The value range fluctuates based on the first temperature increment on the basis of the original benchmark value to adapt to the adjusted metal fluidity requirements.

[0137] For example, if the original temperature reference value of the radial preheating zone corresponding to the low flow velocity section region is 470 degrees Celsius, and the first temperature increment is 10 degrees Celsius, the adjusted radial preheating zone temperature of this region is 480 degrees Celsius; if the original temperature reference value of the high flow velocity section region is 400 degrees Celsius, the adjusted radial preheating zone temperature of this region is 390 degrees Celsius, and the adjusted radial preheating zone temperature range is from 370 degrees Celsius to 530 degrees Celsius.

[0138] It should be noted that the adjusted extrusion speed is the actual operating speed of the extrusion feed mechanism after the parameter adjustment is completed. The value range is adjusted based on the original speed and the reduction of the first extrusion speed to adapt to the overall metal flow rate requirements after adjustment.

[0139] For example, if the original extrusion speed is 2.0 mm / s, the first extrusion speed reduction is 0.2 mm / s, the adjusted extrusion speed is 1.8 mm / s, and the range of the adjusted extrusion speed is 0.5 mm / s to 2.2 mm / s.

[0140] It should be noted that the extreme value of the discharge flow rate difference is the difference between the maximum and minimum flow rates of the metal flow rate at each discharge port after the parameter adjustment is completed. The method of obtaining it is the same as the method of obtaining the extreme value of the discharge flow rate difference before the adjustment, and it is used to verify the adjustment effect.

[0141] For example, after the parameters are adjusted and the system has been running stably for 30 seconds, the metal flow rate of all outlets within the same sampling period can be collected using a laser Doppler velocimeter. The maximum and minimum flow rates can be extracted, and the difference between them can be calculated to obtain the extreme value of the adjusted outlet flow rate difference.

[0142] It should be noted that the common range of values ​​for adjusting the extreme values ​​of the discharge flow rate difference reflects the level of flow rate uniformity after parameter adjustment. It is usually lower than the extreme values ​​of the discharge flow rate difference before adjustment, which is suitable for the uniformity requirements of profile forming.

[0143] For example, the common range of values ​​for adjusting the extreme value of the discharge flow rate difference is 0.1 mm / s to 0.7 mm / s. If the adjusted value is less than the first extreme value of the flow rate difference, it means that the parameter adjustment has achieved the expected effect and there is no need to continue adjusting the parameters.

[0144] S150. When the extreme value of the adjusted discharge flow rate difference is greater than the first extreme value but less than the second extreme value, the preset preheating zone factor is increased to obtain the adjusted preheating zone factor. The low-flow-rate section region and the high-flow-rate section region are redefined based on the adjusted preheating zone factor. The first temperature increment is increased in the radial preheating zone corresponding to the low-flow-rate section region, the first temperature increment is decreased in the radial preheating zone corresponding to the high-flow-rate section region, and the first extrusion speed reduction is decreased.

[0145] In this implementation, the calculated extreme value of the adjusted discharge flow rate difference can be compared with the first and second extreme values ​​of the flow rate difference, respectively. When the extreme value of the adjusted discharge flow rate difference is greater than the first extreme value but less than the second extreme value, a preset parameter adjustment rule can be invoked to obtain a preset preheating zone factor. The original preheating zone factor and the preset preheating zone factor can be added together to obtain the adjusted preheating zone factor, providing a calculation basis for the subsequent re-division of the cross-sectional area.

[0146] It should be noted that the preset preheating zone factor is the single adjustment step size when adjusting the preheating zone factor. Its setting is based on the thickness ratio of the reference profile section and the effect of the initial flow rate adjustment. The numerical range is adapted to the adjustment accuracy requirements of the zone division.

[0147] For example, the preset preheating zone factor can be set to a value range of 0.02 to 0.08. The setting can be based on the decrease in flow rate difference after the first parameter adjustment, so as to avoid large changes in the zone division due to excessive adjustment step size.

[0148] It should be noted that the calculation process of increasing the preheating zone factor to obtain the adjusted preheating zone factor is an incremental adjustment process based on the original preheating zone factor, used to adapt to the adjusted flow rate balance requirements.

[0149] For example, if the original preheating zone factor is 0.88 and the preset preheating zone factor is 0.05, the preheating zone factor can be adjusted to 0.93 by adding 0.88 to 0.05, thus completing the adjustment calculation of the preheating zone factor.

[0150] It should be noted that the common range of values ​​for adjusting the preheating zone factor is determined by both the original preheating zone factor value and the preset preheating zone factor value, and is usually slightly larger than the original preheating zone factor to adapt to the optimization requirements of flow rate deviation.

[0151] For example, the common range of values ​​for the preheating zone factor is 0.62 to 0.98, and its value must be less than 1 to ensure that the subsequent division of the high-velocity section region is within a reasonable radial range.

[0152] In this implementation, the obtained preheating zone adjustment factor can be substituted into the calculation formula for the high-velocity section radius to obtain new high-velocity section radius parameters. Based on the new high-velocity section radius, the high-velocity section region and low-velocity section region in the radial direction of the bar stock can be redefined. The boundary parameters of the two types of regions after redefined division can be synchronized to the preheating system control unit to provide a positional basis for subsequent temperature adjustments.

[0153] It should be noted that the specific process of redetermining the low-velocity and high-velocity cross-sectional areas based on the adjusted preheating zone factor is a process of re-executing the zone division logic based on the updated parameters to adapt to the adjusted process requirements.

[0154] For example, if the bar stock radius is 50 mm, and the preheating zone factor is adjusted to 0.93, the new high-velocity section radius is calculated to be 46.5 mm. The annular region with a radial diameter of 46.5 mm to 50 mm can be defined as the new high-velocity section region, and the circular region with a radial diameter less than or equal to 46.5 mm can be defined as the new low-velocity section region.

[0155] In this implementation, a corresponding radial preheating zone can be matched based on the newly determined low-velocity and high-velocity cross-sectional regions. A temperature adjustment command can be sent to the preheating system to increase the first temperature increment in the radial preheating zone corresponding to the low-velocity cross-sectional region and decrease the first temperature increment in the radial preheating zone corresponding to the high-velocity cross-sectional region. A speed adjustment command can be sent to the extrusion feed mechanism to decrease the extrusion speed by a first extrusion speed reduction, thus completing the adjustment operation of the process parameters for this round.

[0156] This implementation method, after completing the first round of temperature and extrusion speed adjustments, collects the extreme values ​​of the difference in discharge flow rate and uses them as the basis for judging the effect of flow rate adjustment. This can accurately identify the improvement of the flow rate unevenness problem and avoid ineffective parameter adjustments.

[0157] With this implementation, if the adjusted discharge flow rate difference extreme value is still between the first flow rate difference extreme value and the second flow rate difference extreme value, the preheating zone factor is increased by the preset preheating zone factor to obtain the adjusted preheating zone factor, and the high flow rate section region and the low flow rate section region are re-divided. This can adapt to the scenario where the flow rate difference does not meet the standard, and make the region division more in line with the actual molding state.

[0158] By adjusting the temperature and extrusion speed again based on the newly determined low-flow-rate section region and high-flow-rate section region, the flow rate difference between each outlet can be further reduced, thereby improving the molding uniformity of the automotive roof rack profile.

[0159] Figure 7 A flowchart illustrating the fourth method for controlling the extrusion molding of automotive roof rack profiles provided in this application is shown below. Figure 7 As shown, in some implementations, the above method also includes S210 to S220, which will be described in detail below.

[0160] S210. Obtain the supplementary preheating power factor and the supplementary preheating time factor. Obtain the preheating power of the radial preheating zone corresponding to the high-velocity section region as the initial preheating power. Obtain the preheating time of the radial preheating zone corresponding to the high-velocity section region as the initial preheating time. Determine the product of the supplementary preheating power factor and the initial preheating power as the supplementary preheating power. Determine the product of the supplementary preheating time factor and the initial preheating time as the supplementary preheating time.

[0161] Figure 8 A schematic diagram of the workflow for the fourth extrusion molding control method for automotive roof rack profiles provided in this application embodiment is shown below. Figure 8 As shown, in this implementation, the process parameter adjustment library can be called to match the supplementary preheating power factor and supplementary preheating time factor corresponding to the current extrusion condition. The operating parameters of the radial preheating zone corresponding to the high-velocity section can be retrieved to obtain the current preheating power of that zone as the initial preheating power, and the currently set preheating time of that zone as the initial preheating time. These two types of factors and their corresponding initial parameters can be synchronized to the supplementary process calculation module, providing data support for the subsequent calculation of supplementary preheating parameters.

[0162] It should be noted that the supplementary preheating power factor is a proportional coefficient for calculating the supplementary heating power in the radial preheating zone of the high flow rate section. Its setting is based on the magnitude of the extreme value of the discharge flow rate difference and the adjustment requirements of metal flowability, and its numerical range is adapted to the adjustment accuracy of the heating power.

[0163] For example, the numerical range of the supplementary preheating power factor can be set to 0.1 to 0.3. The setting can be based on the difference between the current extreme value of the discharge flow rate difference and the first extreme value of the flow rate difference. The larger the difference, the higher the corresponding value of the supplementary preheating power factor.

[0164] It should be noted that the supplementary preheating time factor is a proportional coefficient used to calculate the supplementary heating time of the radial preheating zone in the high flow rate section area. Its setting is based on the material properties and temperature conduction rate of the reference bar stock, and the numerical range is adapted to the adjustment range of the preheating time.

[0165] For example, the numerical range of the supplementary preheating time factor can be set from 0.05 to 0.15. The setting can be based on the thermal conductivity of the bar stock. The lower the thermal conductivity, the higher the corresponding supplementary preheating time factor value.

[0166] It should be noted that the initial preheating power of the radial preheating zone corresponding to the high flow velocity section is the heating power that was set in that zone before adjustment. The common value range and the power specifications of the preheating equipment are matched with the preheating requirements of the bar stock.

[0167] For example, the common range of initial preheating power for the radial preheating zone corresponding to the high flow velocity section region is 15kW to 35kW, and the specific value is determined by the difference between the radial preheating zone temperature reference value and the current actual temperature.

[0168] It should be noted that the initial preheating time of the radial preheating zone corresponding to the high flow rate section is the total heating time that was set for this zone before adjustment, and the common value range matches the specifications and preheating temperature requirements of the bar stock.

[0169] For example, the common range of initial preheating time for the radial preheating zone corresponding to the high flow rate section region is 10 min to 30 min, and the specific value is determined by the diameter of the bar stock and the target preheating temperature.

[0170] In this implementation, the supplementary preheating power calculation logic can be invoked. The supplementary preheating power factor and the initial preheating power are input, and their product is obtained through multiplication. This product is then determined as the supplementary preheating power. The supplementary preheating power can be synchronized to the control unit of the preheating system, providing a basis for power adjustment in the radial preheating zone corresponding to the high-velocity cross-section region.

[0171] It should be noted that the process of calculating the supplementary preheating power based on the supplementary preheating power factor and the initial preheating power is a process of determining the additional heating power through a proportional coefficient, which is used to increase the temperature of the bar stock in the high flow rate section area and adjust its metal fluidity.

[0172] For example, if the initial preheating power is 25kW and the supplementary preheating power factor is 0.2, the supplementary preheating power is 5kW by multiplying 25kW by 0.2. That is, an additional 5kW of heating power needs to be added on the basis of the initial preheating power.

[0173] It should be noted that the common range of values ​​for supplementary preheating power is determined by the values ​​of the initial preheating power and the supplementary preheating power factor, adapting to the temperature adjustment requirements of high flow rate cross-section areas.

[0174] For example, the common range of values ​​for supplemental preheating power is 1.5kW to 10.5kW, and the specific value must ensure that the total preheating power after adjustment does not exceed the rated power limit of the preheating equipment.

[0175] In this implementation, the supplementary preheating time calculation logic can be invoked. The supplementary preheating time factor and the initial preheating time are input, and their product is obtained through multiplication. This product is then determined as the supplementary preheating time. The supplementary preheating time can be synchronized to the control unit of the preheating system, providing a basis for adjusting the duration of the radial preheating zone corresponding to the high-velocity cross-section region.

[0176] It should be noted that the process of calculating the supplementary preheating time based on the supplementary preheating time factor and the initial preheating time is a process of determining the additional heating time through a proportional coefficient, which is used to ensure the temperature rise effect of the corresponding bar stock position in the high flow rate section area.

[0177] For example, if the initial preheating time is 20 minutes and the supplementary preheating time factor is 0.1, the supplementary preheating time is 2 minutes by multiplying 20 minutes by 0.1. That is, an additional 2 minutes of heating time needs to be added on the basis of the initial preheating time.

[0178] It should be noted that the common range of values ​​for supplementary preheating time is determined by the values ​​of the initial preheating time and the supplementary preheating time factor, adapting to the temperature conduction requirements of high flow rate cross-section areas.

[0179] For example, the common range for supplementary preheating time is 0.5 min to 4.5 min, and the specific value must ensure that the adjusted total preheating time matches the overall production cycle.

[0180] S220. When the extreme value of the discharge flow rate difference is greater than the first extreme value and less than the second extreme value, the radial preheating zone corresponding to the high flow rate section area is preheated with supplementary preheating power and supplementary preheating time to improve the surface fluidity of the high flow rate section area.

[0181] In this implementation, the calculated extreme value of the adjusted discharge flow rate difference can be compared with the first and second extreme values ​​of the flow rate difference. When the extreme value of the adjusted discharge flow rate difference is greater than the first extreme value but less than the second extreme value, a supplementary preheating command can be sent to the control unit of the preheating system, carrying the calculated supplementary preheating power and supplementary preheating time parameters. The radial preheating zone corresponding to the high flow rate section can be controlled to perform supplementary preheating operation according to the parameters, thereby adjusting the surface flowability of the high flow rate section.

[0182] It should be noted that the specific operation procedure for supplementing the radial preheating zone corresponding to the high flow velocity section area with supplementary preheating power and supplementary preheating time is an additional heating process that is added on the basis of the original preheating process, and it needs to be matched with the feed progress of the bar stock.

[0183] For example, during the dwell stage after the bar stock has completed its initial preheating and before entering the extrusion die, the heating power of the radial preheating zone corresponding to the high flow rate section area can be increased by adding supplementary preheating power on the basis of the original power. After the supplementary preheating time is continuously run, the additional heating is stopped, and the supplementary preheating operation is completed.

[0184] It should be noted that after supplemental preheating, the surface temperature of the high-flow-rate section will be increased based on the original preheating temperature. The temperature change range is matched with the values ​​of supplemental preheating power and supplemental preheating time to adapt to the flow adjustment requirements.

[0185] For example, if the surface temperature of the high-velocity section region is 400 degrees Celsius before supplemental preheating, the surface temperature of the region changes from 410 degrees Celsius to 425 degrees Celsius after supplemental preheating. The temperature increase is positively correlated with the parameter settings of the supplemental preheating.

[0186] This implementation method obtains the supplementary preheating power factor, the supplementary preheating time factor, and the initial preheating power and initial preheating time of the radial preheating zone corresponding to the high flow velocity section region. The supplementary preheating power and supplementary preheating time are calculated respectively, which can clearly define the execution parameters of supplementary preheating and avoid the arbitrariness of preheating adjustment.

[0187] With this implementation, when the extreme value of the discharge flow rate difference is still between the first and second extreme values, supplementary preheating is performed on the radial preheating zone corresponding to the high flow rate section area according to the supplementary preheating power and supplementary preheating time. This can specifically improve the material flowability in this area and adapt to the advanced requirements of flow rate adjustment.

[0188] By utilizing this method, the surface fluidity of the high-flow-rate section area is improved through supplementary preheating, which can further reduce the flow rate difference between each outlet, reduce molding defects, and improve the molding quality stability of automotive roof rack profiles.

[0189] In some implementations, the above method further includes: when supplementing preheating the radial preheating zone corresponding to the high flow velocity section region according to the supplementary preheating power and supplementary preheating time, the extrusion speed at different stages is simultaneously reduced by the supplementary extrusion speed reduction.

[0190] In this implementation, while issuing supplementary preheating commands to the radial preheating zone corresponding to the high-velocity section, the extrusion speed adjustment module can be invoked to obtain the supplementary extrusion speed reduction to match the current operating conditions. Based on the different stages of the extrusion process, a synchronous speed adjustment command can be issued to the extrusion feed mechanism to synchronously reduce the supplementary extrusion speed reduction at different stages throughout the entire supplementary preheating cycle. The adjusted extrusion speed parameters can be recorded and stored in the process operation log.

[0191] It should be noted that the reduction in the supplementary extrusion speed is the adjustment range of the extrusion speed during the supplementary preheating stage. Its setting is based on the temperature increase during supplementary preheating and the degree of change in metal fluidity, and the numerical range is adapted to the stability requirements of the extrusion process.

[0192] For example, the range of the supplementary extrusion speed reduction can be set from 0.05 mm / s to 0.2 mm / s. The setting can be based on the temperature rise in the high flow rate section area after supplementary preheating. The greater the temperature rise, the higher the corresponding supplementary extrusion speed reduction value.

[0193] It should be noted that the different extrusion stages in the supplementary preheating process are divided into different operating stages according to the bar feed progress and the preheating execution node, and each stage corresponds to different extrusion process requirements.

[0194] For example, the supplementary preheating process can be divided into three extrusion stages: the bar stock feeding stage at the initial stage of supplementary preheating, the bar stock initial entry stage during the middle stage of supplementary preheating, and the bar stock full entry stage before the end of supplementary preheating.

[0195] For example, if the extrusion speed before preheating is 1.8 mm / s and the extrusion speed is reduced by 0.1 mm / s, the common range of the adjusted extrusion speed is 1.6 mm / s to 1.75 mm / s. The adjusted speed must be higher than the minimum operating speed threshold of the extrusion feed mechanism.

[0196] It should be noted that the timing requirements for the simultaneous adjustment of preheating and extrusion speed are time node rules to ensure that the effects of the two types of adjustments match, and to avoid the expansion of flow rate deviation caused by asynchronous parameter adjustments.

[0197] For example, at the same time that the supplementary preheating power output is started in the radial preheating zone corresponding to the high flow rate section region, a speed adjustment command can be sent to the extrusion feed mechanism to simultaneously perform the speed reduction operation, and the end time of the two types of adjustments is consistent.

[0198] By implementing this method, during the process of supplementing preheating in the radial preheating zone corresponding to the high flow velocity section region according to the supplementary preheating power and supplementary preheating time, the extrusion speed at different stages is simultaneously reduced by the supplementary extrusion speed reduction. This allows the extrusion feed rhythm to match the material flow characteristics after supplementary preheating, avoiding the problem of asynchronous flow rate adjustment.

[0199] This implementation method adopts a mode of linkage adjustment of preheating parameters and extrusion speed, which eliminates the need to adjust the two types of parameters separately, thereby shortening the response time of overall flow rate adjustment and improving the adjustment efficiency of the extrusion process.

[0200] Through this implementation method, the synchronous adjustment of the two types of parameters can further balance the metal flow rate at each outlet, reduce the risk of temporary flow rate fluctuations caused by asynchronous parameter adjustments, ensure the stability of the molding process of automotive roof rack profiles, and reduce molding defects.

[0201] In some implementations, the above method further includes: a supplementary preheating power factor of 1.2 to 1.5; a supplementary preheating time factor of 0.1 to 0.2; and a supplementary extrusion speed reduction of 0.05 to 0.1.

[0202] In this implementation, an appropriate supplementary preheating power factor can be selected within the range of 1.2 to 1.5 based on parameters such as the flow rate deviation and bar material properties under the current extrusion conditions. The selected supplementary preheating power factor can be substituted into the calculation formula for supplementary preheating power to obtain the supplementary preheating power parameters for the corresponding scenario, providing a basis for adjusting the preheating power in high-flow-rate cross-section areas.

[0203] It should be noted that the specific value of the supplementary preheating power factor in the range of 1.2 to 1.5 is positively correlated with the magnitude of the extreme value of the discharge flow rate difference. The larger the flow rate difference, the higher the value should be, to ensure that the temperature adjustment range matches the flow rate balance requirement.

[0204] For example, when the extreme value of the discharge flow rate difference is adjusted to 0.3 mm / s, which is close to the first extreme value of the flow rate difference, 1.2 can be selected as the supplementary preheating power factor; when the extreme value of the discharge flow rate difference is adjusted to 0.7 mm / s, which is close to the second extreme value of the flow rate difference, 1.5 can be selected as the supplementary preheating power factor.

[0205] In this implementation, an appropriate supplementary preheating time factor can be selected within the range of 0.1 to 0.2 based on parameters such as the thermal conductivity of the bar stock and the heating efficiency of the preheating equipment. The selected supplementary preheating time factor can be substituted into the calculation formula for the supplementary preheating time to obtain the supplementary preheating time parameter for the corresponding scenario, providing a basis for adjusting the preheating time in high-velocity cross-section regions.

[0206] It should be noted that the specific value of the supplementary preheating time factor in the range of 0.1 to 0.2 is negatively correlated with the thermal conductivity of the bar stock. The lower the thermal conductivity, the higher the value should be, to ensure that the surface of the bar stock can reach the target preheating temperature.

[0207] For example, when the bar stock is a 6-series aluminum alloy with good thermal conductivity, 0.1 can be selected as the supplementary preheating time factor; when the bar stock is a 7-series aluminum alloy with poor thermal conductivity, 0.2 can be selected as the supplementary preheating time factor.

[0208] In this implementation, an appropriate supplementary extrusion speed reduction can be selected within the range of 0.05 to 0.1, based on parameters such as the operational stability of the extrusion equipment and the forming accuracy requirements of the profile. The selected supplementary extrusion speed reduction can be synchronized to the control unit of the extrusion feed mechanism, providing a basis for adjusting the extrusion speed during the supplementary preheating stage.

[0209] It should be noted that the specific value of the supplementary extrusion speed reduction in the range of 0.05 to 0.1 is positively correlated with the form and position tolerance requirements of the profile. The higher the precision requirement, the higher the value should be selected to ensure the uniformity of the flow rate during the extrusion process.

[0210] By setting the supplementary preheating power factor to 1.2 to 1.5, the radial preheating zone corresponding to the high flow rate section area can obtain sufficient supplementary heat to improve the material flowability. Setting the supplementary preheating time factor to 0.1 to 0.2 can control the supplementary preheating time within a reasonable range, which allows the heat to fully penetrate into the bar stock in the high flow rate section area without affecting the bar stock preheating temperature in the low flow rate section area.

[0211] By setting the supplementary extrusion speed reduction to 0.05 to 0.1, the material flow characteristics after supplementary preheating can be matched. This can help reduce the difference in discharge flow rate without causing a significant slowdown in production pace due to excessive extrusion speed reduction, thus ensuring molding quality while taking into account production efficiency.

[0212] In some implementations, the above method further includes: when the extreme value of the discharge flow rate difference is greater than the second extreme value of the flow rate difference, obtaining a second temperature increment and a second extrusion speed reduction. A low-flow-rate section region and a high-flow-rate section region are determined. For the radial preheating zone corresponding to the low-flow-rate section region, the second temperature increment is increased; for the radial preheating zone corresponding to the high-flow-rate section region, the second temperature increment is decreased. Simultaneously, the extrusion speed is reduced by the second extrusion speed reduction until the extreme value of the discharge flow rate difference falls back to less than the first extreme value of the flow rate difference. Wherein, the second temperature increment is greater than the first temperature increment, and the second extrusion speed reduction is greater than the first extrusion speed reduction.

[0213] In this implementation, the calculated extreme value of the discharge flow rate difference can be compared with a preset second extreme value. When the extreme value of the discharge flow rate difference is greater than the second extreme value, the process parameter adjustment library can be called to obtain the second temperature increment and the second extrusion speed reduction that match the current large flow rate deviation scenario. These two types of adjustment parameters can be synchronized to the execution control module, providing a basis for subsequent temperature and speed adjustments.

[0214] It should be noted that the second temperature increment is the temperature adjustment step size for scenarios with large flow rate deviations. Its value range is larger than that of the first temperature increment, which adapts to the temperature adjustment needs when the flow rate deviation is large, and ensures that the flow rate differences in various regions are quickly reduced.

[0215] For example, the numerical range of the second temperature increment can be set to 15 degrees Celsius to 25 degrees Celsius. If the first temperature increment is 10 degrees Celsius, the second temperature increment can be 20 degrees Celsius, which is higher than the first temperature increment, to meet the need for rapid adjustment in scenarios with large deviations.

[0216] It should be noted that the second extrusion speed reduction is a speed adjustment step size for scenarios with large flow rate deviations. Its value range is larger than that of the first extrusion speed reduction, which adapts to the speed adjustment needs when the flow rate deviation is large, and ensures that the overall flow rate quickly stabilizes.

[0217] For example, the numerical range of the second extrusion speed reduction can be set from 0.3 mm / s to 0.5 mm / s. If the first extrusion speed reduction is 0.2 mm / s, the second extrusion speed reduction can be 0.4 mm / s, which is higher than the first extrusion speed reduction, thus meeting the need for rapid adjustment in scenarios with large deviations.

[0218] In this implementation, low-velocity and high-velocity cross-sectional areas can be determined based on the current metal flow rate detection results at each discharge port through a preset partitioning logic. The radial preheating zones corresponding to the two types of areas can be matched according to a pre-established mapping relationship between the cross-sectional areas and the radial preheating zones. Adjustment commands can be simultaneously issued to the preheating system and the extrusion feeding mechanism, increasing the second temperature increment in the radial preheating zone corresponding to the low-velocity cross-sectional area and decreasing the second temperature increment in the radial preheating zone corresponding to the high-velocity cross-sectional area, while simultaneously decreasing the second extrusion speed reduction. The extreme values ​​of the adjusted discharge velocity difference can be collected in real time, and the adjustment operation can be continuously executed until the extreme value of the discharge velocity difference falls back to less than the first extreme value.

[0219] It should be noted that the rules for determining the low-velocity section region and the high-velocity section region in the scenario where the extreme value of the discharge velocity difference is greater than the extreme value of the second velocity difference are based on the deviation range of the flow velocity and the average flow velocity at each discharge port. The deviation range threshold is higher than the judgment threshold for the small velocity deviation scenario.

[0220] For example, the average value of the metal flow velocity at all outlets can be calculated, and the cross-sectional area with a flow velocity more than 20% lower than the average value can be defined as a low flow velocity cross-sectional area, and the cross-sectional area with a flow velocity more than 20% higher than the average value can be defined as a high flow velocity cross-sectional area.

[0221] It should be noted that the operation of increasing the second temperature increment in the radial preheating zone corresponding to the low flow rate section is a temperature adjustment process for scenarios with large flow rate deviations. The adjustment range is higher than that in conventional adjustment scenarios, which quickly improves the metal fluidity in the low flow rate region.

[0222] For example, if the current temperature reference value of the radial preheating zone corresponding to the low flow rate section is 470 degrees Celsius and the second temperature increment is 20 degrees Celsius, the temperature reference value of the radial preheating zone can be adjusted to 490 degrees Celsius, and the preheating system can be controlled to operate according to the adjusted temperature reference value.

[0223] It should be noted that the operation of reducing the second temperature increment of the radial preheating zone corresponding to the high flow rate section is a temperature adjustment process for scenarios with large flow rate deviations. The adjustment range is higher than that of conventional adjustment scenarios, which quickly reduces the metal fluidity in the high flow rate region.

[0224] For example, if the current temperature reference value of the radial preheating zone corresponding to the high flow rate section is 400 degrees Celsius and the second temperature increment is 20 degrees Celsius, the temperature reference value of the radial preheating zone can be lowered to 380 degrees Celsius, and the preheating system can be controlled to operate according to the adjusted temperature reference value.

[0225] With this implementation, when the extreme value of the discharge flow rate difference is greater than the extreme value of the second flow rate difference, the second temperature increment and the second extrusion speed reduction are used for adjustment. The second temperature increment is greater than the first temperature increment, and the second extrusion speed reduction is greater than the first extrusion speed reduction. This can provide stronger adjustment for scenarios with excessive flow rate differences and quickly reduce flow rate deviation.

[0226] Figure 9 A flowchart illustrating the fifth method for controlling the extrusion molding of automotive roof rack profiles provided in this application is shown below. Figure 9 As shown, in some implementations, the above method also includes S310 to S320, which will be described in detail below.

[0227] S310. Determine the difference in metal flow velocity at multiple outlets at adjacent moments, as the absolute flow velocity difference. Determine the difference between the metal flow velocity at multiple outlets and the metal flow velocity reference value, as the reference flow velocity difference.

[0228] Figure 10 A schematic diagram of the workflow for the fifth type of extrusion molding control method for automotive roof rack profiles provided in this application embodiment is shown below. Figure 10 As shown, in this implementation, the metal flow rate of each outlet can be collected according to a preset sampling period, the flow rate data of the same outlet at two adjacent sampling times can be extracted, the difference between the two can be calculated, and the difference can be determined as the absolute difference of flow rate.

[0229] It should be noted that the time interval between adjacent moments is the time difference between two flow rate samples. It is set based on the flow rate fluctuation frequency of the reference extrusion process and the sampling accuracy of the detection equipment to ensure that abnormal changes in flow rate can be captured in a timely manner.

[0230] For example, the time interval between adjacent moments can be set to 1 to 5 seconds. When the extrusion speed is high and the profile cross-section is complex, a time interval of 1 second can be selected; when the extrusion speed is low and the profile cross-section structure is simple, a time interval of 5 seconds can be selected.

[0231] It should be noted that the absolute difference in flow rate is an indicator that reflects the degree of fluctuation in the metal flow rate at the same outlet over time. It is obtained by subtracting the flow rates at adjacent moments, and its value is directly related to the stability of the flow rate.

[0232] For example, if the metal flow rate at a certain outlet is 1.8 mm / s at time t1 and 1.9 mm / s at the adjacent time t2, the difference between the two is calculated to be 0.1 mm / s. This value is the absolute difference in flow rate, and the common range of absolute difference in flow rate is 0.02 mm / s to 0.3 mm / s.

[0233] In this implementation, a preset metal flow rate reference value can be retrieved, and the difference between the real-time metal flow rate of each outlet and the reference value can be calculated. The resulting difference is then determined as the reference flow rate difference.

[0234] It should be noted that the metal flow rate benchmark value is a preset standard value for the metal flow rate at the outlet. It is determined by referring to the process data of historical qualified batches and the current forming requirements of the profile. It serves as a reference for judging whether the flow rate is within the normal range.

[0235] For example, the metal flow rate reference value can be determined based on the average discharge flow rate of the same type of material in a historical normal batch, or it can be calculated based on the initial extrusion speed and the shrinkage rate of the die cavity. The common range of the metal flow rate reference value is 0.8 mm / s to 2.5 mm / s.

[0236] It should be noted that the reference flow rate difference is an indicator reflecting the degree of deviation between the real-time metal flow rate and the standard value. It is obtained by subtracting the reference metal flow rate from the real-time flow rate. The sign and magnitude of the value reflect the direction and degree of deviation, respectively.

[0237] For example, if the reference metal flow rate is 1.7 mm / s and the real-time metal flow rate at a certain outlet is 1.9 mm / s, the difference between the two is calculated to be 0.2 mm / s. This value is the reference flow rate difference. The common range of the reference flow rate difference is -0.4 mm / s to 0.4 mm / s.

[0238] S320. When the absolute difference in flow rate is greater than the preset absolute difference in flow rate, or when the reference flow rate difference is greater than the preset reference flow rate difference, the first temperature reference value is increased synchronously for the radial preheating zone temperature reference value of the bar stock at different radial positions, and the second temperature reference value is decreased for the axial heating zone temperature reference value at different axial positions.

[0239] In this implementation, the calculated absolute flow rate difference can be compared with a preset absolute flow rate difference, and the reference flow rate difference can be compared with a preset reference flow rate difference. When the absolute flow rate difference is greater than the preset absolute flow rate difference, or the reference flow rate difference is greater than the preset reference flow rate difference, the temperature reference value adjustment logic can be invoked to obtain the corresponding first and second temperature reference values. An adjustment command can be issued to the control unit of the preheating system to synchronously increase the first temperature reference value for the radial preheating zone at different radial positions of the bar stock, and decrease the second temperature reference value for the axial heating zone at different axial positions.

[0240] It should be noted that the preset absolute difference in flow rate is a threshold for determining whether the flow rate fluctuation over time exceeds the normal range. Its setting is based on the stability requirements of the extrusion process and the flow rate fluctuation data in historical production, and the value range is adapted to different profile forming accuracy requirements.

[0241] For example, the numerical range of the preset absolute flow rate difference can be set from 0.1 mm / s to 0.2 mm / s. For profiles with high form and position tolerance requirements, 0.1 mm / s is selected as the preset absolute flow rate difference; for profiles with ordinary precision requirements, 0.2 mm / s is selected as the preset absolute flow rate difference.

[0242] It should be noted that the preset reference flow rate difference is a threshold for determining whether the deviation between the real-time flow rate and the standard value exceeds the normal range. Its setting is based on the quality requirements of the reference profile forming and the allowable flow rate deviation range of historical qualified batches. The numerical range is adapted to different process stability requirements.

[0243] For example, the range of the preset reference flow rate difference can be set from 0.15 mm / s to 0.3 mm / s. For profiles with high mechanical performance requirements, 0.15 mm / s is selected as the preset reference flow rate difference; for profiles used in general applications, 0.3 mm / s is selected as the preset reference flow rate difference.

[0244] It should be noted that the first temperature reference value is the upward adjustment step of the radial preheating zone temperature reference value. Its value range is adapted to the overall radial temperature adjustment needs, so as to avoid drastic changes in metal fluidity caused by excessive temperature adjustment.

[0245] For example, the numerical range of the first temperature reference value can be set to 3 degrees Celsius to 8 degrees Celsius. The specific value can be selected according to the magnitude of the flow rate deviation. The larger the deviation, the higher the selected first temperature reference value.

[0246] It should be noted that the second temperature reference value is the downward adjustment step size of the temperature reference value in the axial heating range. Its value range is adapted to the overall axial temperature adjustment needs, so as to avoid excessive axial temperature fluctuations affecting the overall heating uniformity of the bar stock.

[0247] For example, the numerical range of the second temperature reference value can be set to 5 degrees Celsius to 10 degrees Celsius. The specific value can be selected according to the magnitude of the flow rate deviation. The larger the deviation, the higher the selected second temperature reference value.

[0248] It should be noted that the operation of simultaneously increasing the first temperature reference value of the radial preheating zone temperature reference value at different radial positions is a process of uniformly raising the temperature reference value of all radial preheating zones, which is used to improve the temperature of each radial region of the bar stock as a whole and improve the overall fluidity.

[0249] For example, if the temperature reference value of the radial core region of the bar stock is 390 degrees Celsius, the middle region is 440 degrees Celsius, and the surface region is 490 degrees Celsius, and the first temperature reference value is 5 degrees Celsius, the temperature reference values ​​of the three regions can be adjusted to 395 degrees Celsius, 445 degrees Celsius, and 495 degrees Celsius respectively, and the temperature adjustment of all radial preheating zones can be completed simultaneously.

[0250] It should be noted that reducing the second temperature reference value for the axial heating range at different axial positions is a process of uniformly lowering the temperature reference value for all axial heating ranges. This is used to smooth the axial heating gradient of the bar stock and reduce the difference in axial flow velocity.

[0251] For example, if the temperature reference value for the front end region of the bar stock is 440 degrees Celsius, the middle region is 470 degrees Celsius, and the rear end region is 510 degrees Celsius, and the second temperature reference value is 8 degrees Celsius, the temperature reference values ​​for the three regions can be lowered to 432 degrees Celsius, 462 degrees Celsius, and 502 degrees Celsius respectively, and the temperature adjustment of all axial heating ranges can be completed simultaneously.

[0252] It should be noted that the two judgment conditions, the absolute difference in flow rate and the difference in reference flow rate, are OR-triggered and have no priority difference. The subsequent temperature reference value adjustment operation can be triggered when either condition is met.

[0253] This implementation calculates the difference in metal flow velocity at multiple outlets at adjacent moments as the absolute flow velocity difference, and simultaneously calculates the difference between the metal flow velocity at multiple outlets and the metal flow velocity reference value as the reference flow velocity difference. When the absolute flow velocity difference is greater than the preset absolute flow velocity difference or the reference flow velocity difference is greater than the preset reference flow velocity difference, the first temperature reference value is increased synchronously for the radial preheating zone temperature reference value at different radial positions. This can raise the overall radial base temperature of the bar stock, accelerate the material flow rate in high-flow velocity and low-flow velocity regions, and improve the flow velocity balance in extrusion molding.

[0254] By simultaneously reducing the second temperature reference value of the axial heating range at different axial positions, the problem of excessive flow caused by excessive axial heating of the bar stock can be avoided. By adjusting the temperature reference in both radial and axial directions, the discharge flow rate can be quickly brought back to a stable range, ensuring a smooth molding process.

[0255] Figure 11 A flowchart illustrating the sixth method for controlling the extrusion molding of automotive roof rack profiles provided in this application embodiment is shown below. Figure 11 As shown, in some implementations, the above method also includes S330 to S340, which will be described in detail below.

[0256] S330. The first temperature reference value is increased synchronously for the radial preheating zone temperature reference value of the bar stock at different radial positions, and the second temperature reference value is decreased for the axial heating zone temperature reference value at different axial positions. After the extrusion speed is reduced by the first extrusion speed reduction, the absolute difference in flow rate is obtained as the adjustment absolute difference in flow rate, and the reference flow rate difference is obtained as the adjustment reference flow rate difference.

[0257] In this implementation, after adjusting the temperature baseline values ​​of all radial preheating zones, lowering the temperature baseline values ​​of all axial heating zones, and reducing the extrusion speed, a preset process stabilization period can be waited for to ensure that the effects of temperature and speed adjustments are transmitted to the discharge end. Metal flow velocity data at each discharge port can be re-acquired using a flow velocity detection device. The absolute difference in flow velocity between adjacent moments can be calculated to obtain the adjusted flow velocity, and the difference between the real-time flow velocity and the metal flow velocity baseline value can be calculated to obtain the adjusted baseline flow velocity difference. These two types of adjusted differences can be synchronized to the process analysis module for evaluating the effectiveness of the parameter adjustments.

[0258] It should be noted that the adjusted radial preheating zone temperature reference value is the operating reference temperature of each radial preheating zone after the parameter adjustment is completed. The value range is based on the original reference value and is increased based on the first temperature reference value to adapt to the overall flow improvement needs.

[0259] For example, if the temperature reference value of the radial core region before adjustment is 390 degrees Celsius, the temperature reference value of the middle region is 440 degrees Celsius, the temperature reference value of the surface region is 490 degrees Celsius, and the temperature reference value of the first temperature reference value is 5 degrees Celsius, the temperature reference values ​​of the radial preheating zone after adjustment are 395 degrees Celsius, 445 degrees Celsius, and 495 degrees Celsius, respectively, with a value range of 370 degrees Celsius to 535 degrees Celsius.

[0260] It should be noted that the adjusted axial heating range temperature reference value is the operating reference temperature of each axial heating range after the parameter adjustment is completed. The value range is based on the original reference value and is adjusted downward based on the second temperature reference value to adapt to the requirement of a gentle axial heating gradient.

[0261] For example, if the temperature reference value of the axial front end region before adjustment is 440 degrees Celsius, the middle region is 470 degrees Celsius, and the rear end region is 510 degrees Celsius, and the second temperature reference value is 8 degrees Celsius, the temperature reference values ​​of the axial heating range after adjustment are 432 degrees Celsius, 462 degrees Celsius, and 502 degrees Celsius, respectively, with a value range of 395 degrees Celsius to 515 degrees Celsius.

[0262] It should be noted that the adjusted extrusion speed is the actual operating speed of the extrusion feed mechanism after the parameter adjustment is completed. The value range is adjusted based on the original speed and the reduction of the first extrusion speed to adapt to the adjusted metal flow characteristics.

[0263] For example, if the extrusion speed before adjustment is 2.0 mm / s, the first extrusion speed reduction is 0.2 mm / s, the extrusion speed after adjustment is 1.8 mm / s, and the range of the adjusted extrusion speed value is from 0.5 mm / s to 2.2 mm / s.

[0264] It should be noted that the adjusted absolute difference in flow rate is the difference in metal flow rate at adjacent moments at the same outlet after the parameter adjustment is completed. The method of obtaining it is the same as that of the absolute difference in flow rate before adjustment, and it is used to verify the improvement effect of flow rate fluctuation.

[0265] For example, after the parameters are adjusted and the system has been running stably for three sampling cycles, two consecutive flow rate data points can be collected from each outlet. The difference between the two data points can be calculated to obtain the absolute difference in the adjusted flow rate. The common range of these values ​​is 0.02 mm / s to 0.15 mm / s.

[0266] It should be noted that the adjusted reference flow rate difference is the difference between the real-time metal flow rate and the reference metal flow rate after the parameter adjustment is completed. The method of obtaining the difference is the same as that of the reference flow rate difference before adjustment, and it is used to verify the improvement effect of the flow rate deviation.

[0267] For example, after the parameters are adjusted and three sampling cycles are run stably, the real-time flow rate data of each outlet can be collected, and the preset metal flow rate reference value can be subtracted to obtain the adjustment reference flow rate difference. The common value range is -0.2mm / s to 0.2mm / s.

[0268] S340. When the absolute difference of the adjusted flow rate is greater than the preset absolute difference of the flow rate, or when the difference of the adjusted reference flow rate is greater than the preset reference flow rate difference, the preset initial extrusion speed is increased.

[0269] In this implementation, the calculated absolute difference in adjusted flow rate is compared with the preset absolute difference in flow rate, and the difference in adjusted reference flow rate is also compared with the preset reference flow rate difference. When the absolute difference in adjusted flow rate is greater than the absolute difference in preset flow rate, or when the difference in adjusted reference flow rate is greater than the preset reference flow rate difference, the initial extrusion speed adjustment logic can be invoked to obtain the corresponding preset initial extrusion speed increment. The original initial extrusion speed and the preset initial extrusion speed can be added together to obtain the adjusted initial extrusion speed, which is then synchronized to the control unit of the extrusion feed mechanism, providing updated parameter data for setting the extrusion speed of subsequent batches of bars.

[0270] It should be noted that the preset initial extrusion speed is the step size for adjusting the initial extrusion speed. Its setting is based on the magnitude of the current flow rate deviation and the operating capacity of the extrusion equipment. The value range is adapted to the adjustment accuracy requirements of the initial extrusion speed to avoid excessive speed adjustment affecting the extrusion stability.

[0271] For example, the preset initial extrusion speed can be set to a range of 0.1 mm / s to 0.3 mm / s. The setting can be based on the difference between the adjusted flow rate difference and the threshold value. The larger the difference, the higher the preset initial extrusion speed value.

[0272] It should be noted that the common range of values ​​for the increased initial extrusion speed is determined by the values ​​of the original initial extrusion speed and the preset initial extrusion speed, and must be lower than the maximum rated extrusion speed of the extrusion equipment to ensure the safe operation of the equipment.

[0273] For example, the common range of values ​​for the increased initial extrusion speed is 0.9 mm / s to 2.8 mm / s. The specific value needs to be confirmed in conjunction with the forming requirements of the profile and the operating threshold of the equipment to avoid exceeding the speed range allowed by the process.

[0274] By using this method, after completing the radial and axial temperature reference adjustment and the extrusion speed adjustment, the absolute difference of the adjusted flow rate and the difference of the adjusted reference flow rate are collected as the basis for judgment. This can accurately verify the effect of the first round of parameter adjustment and provide a reliable reference for subsequent secondary adjustments.

[0275] With this implementation, if the adjusted absolute flow rate difference is still greater than the preset absolute flow rate difference, or if the adjusted reference flow rate difference is still greater than the preset reference flow rate difference, the initial extrusion speed is increased by the preset initial extrusion speed. This can adapt to the material flow characteristics after temperature adjustment and further match the flow rate requirements of each outlet. By adopting a progressive adjustment logic for temperature and extrusion speed, large fluctuations in flow rate and deviations from the reference value can be quickly eliminated, ensuring the stability of the extrusion process and reducing the probability of molding defects in automotive roof rack profiles.

[0276] This application also provides an automotive roof rack profile, manufactured using the extrusion molding control method for automotive roof rack profiles described above.

[0277] The car roof rack profile in this embodiment is manufactured using the aforementioned extrusion molding control method for car roof rack profiles. During the production process, the molding feeding requirements of thin-walled and thick-walled areas of the profile can be matched in a targeted manner to ensure uniform discharge flow rate in each area, reduce problems such as uneven wall thickness and deformation during molding, and improve the structural consistency of the finished product. The resulting car roof rack profile has more uniform molding density in each area and higher structural strength and stability, which can better meet the load-bearing and impact resistance requirements of the roof rack and extend the service life of the product.

[0278] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for controlling the extrusion molding of automotive roof rack profiles, characterized in that, The method includes: Obtain mold cavity structure parameters, profile cross-section functional zoning parameters, and historical normal batch process data; based on the mold cavity structure parameters, multiple profile cross-section functional zoning parameters, and historical normal batch process data, determine the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed of the bar stock at different radial positions; before feeding the bar stock, start the preheating system and extrusion feeding mechanism according to the radial preheating zone temperature reference value, the axial heating zone temperature reference value, and the initial extrusion speed; among them, multiple profile cross-section functional zoning includes thin-walled and thick-walled regions of the profile. The position of the bar stock closer to the surface in the radial direction corresponds to a higher preheating zone temperature reference value, the position of the bar stock closer to the surface in the radial direction is used for extruding and forming the thick-walled section of the profile, the position of the bar stock closer to the core in the radial direction corresponds to a lower preheating zone temperature reference value, and the position of the bar stock closer to the core in the radial direction is used for extruding and forming the thin-walled section of the profile; During the extrusion process, the actual temperature of the radial preheating zone of the bar stock at different radial positions and the actual temperature of the axial heating zone of the bar stock at different axial positions are obtained; the metal flow rate of multiple outlets corresponding to multiple profile cross-section functional zones is obtained, and the maximum and minimum flow rates among the multiple outlet metal flow rates are determined; the difference between the maximum and minimum flow rates is determined as the extreme value of the outlet flow rate difference. When the extreme value of the discharge flow rate difference is less than the first extreme value of the flow rate difference, the temperature reference value of the radial preheating zone at different radial positions remains unchanged; when the extreme value of the discharge flow rate difference is greater than the first extreme value of the flow rate difference but less than the second extreme value of the flow rate difference, the first temperature increment and the first extrusion speed reduction are obtained; the low flow rate section region and the high flow rate section region are determined, the first temperature increment is increased for the radial preheating zone corresponding to the low flow rate section region, the first temperature increment is decreased for the radial preheating zone corresponding to the high flow rate section region, and the first extrusion speed reduction is decreased for the extrusion speed.

2. The method according to claim 1, characterized in that, Determine the low-velocity and high-velocity cross-sectional regions, including: Obtain the thick-walled cross-sectional area and bar cross-sectional area corresponding to the thick-walled section; determine the preheating zone factor of the thick-walled cross-sectional area and bar cross-sectional area corresponding to the thick-walled section; determine the product of the bar radius and the preheating zone factor as the high-velocity section radius; The annular region corresponding to the radius of the high-velocity section from the surface of the bar stock to the center of the bar stock is defined as the high-velocity section region; the region of the bar stock cross section other than the high-velocity section region is defined as the low-velocity section region.

3. The method according to claim 2, characterized in that, The method further includes: Increase the first temperature increment in the radial preheating zone corresponding to the low flow rate section area, decrease the first temperature increment in the radial preheating zone corresponding to the high flow rate section area, and decrease the first extrusion speed reduction in the extrusion speed to obtain the extreme value of the adjusted discharge flow rate difference. When the extreme value of the adjusted discharge flow rate difference is greater than the first flow rate difference extreme value but less than the second flow rate difference extreme value, the preset preheating zone factor is increased to obtain the adjusted preheating zone factor; the low flow rate section region and the high flow rate section region are re-determined based on the adjusted preheating zone factor; the first temperature increment is increased for the radial preheating zone corresponding to the low flow rate section region, the first temperature increment is decreased for the radial preheating zone corresponding to the high flow rate section region, and the first extrusion speed reduction is decreased for the extrusion speed.

4. The method according to claim 3, characterized in that, The method further includes: Obtain the supplementary preheating power factor and the supplementary preheating time factor; obtain the preheating power of the radial preheating zone corresponding to the high flow velocity section region as the initial preheating power; obtain the preheating time of the radial preheating zone corresponding to the high flow velocity section region as the initial preheating time; determine the product of the supplementary preheating power factor and the initial preheating power as the supplementary preheating power; determine the product of the supplementary preheating time factor and the initial preheating time as the supplementary preheating time. When the extreme value of the discharge velocity difference is greater than the first extreme value but less than the second extreme value, the radial preheating zone corresponding to the high velocity section area is preheated with supplementary preheating power and supplementary preheating time to improve the surface fluidity of the high velocity section area.

5. The method according to claim 4, characterized in that, The method further includes: When supplementing preheating in the radial preheating zone corresponding to the high flow velocity section region according to the supplementary preheating power and supplementary preheating time, the extrusion speed at different stages is reduced simultaneously by the supplementary extrusion speed reduction.

6. The method according to claim 5, characterized in that, The method further includes: The supplementary preheating power factor is 1.2 to 1.5; the supplementary preheating time factor is 0.1 to 0.2; and the supplementary extrusion speed reduction is 0.05 to 0.

1.

7. The method according to claim 6, characterized in that, The method further includes: When the extreme value of the discharge flow rate difference is greater than the extreme value of the second flow rate difference, the second temperature increment and the second extrusion speed reduction are obtained; the low flow rate section region and the high flow rate section region are determined, the second temperature increment is increased in the radial preheating zone corresponding to the low flow rate section region, and the second temperature increment is decreased in the radial preheating zone corresponding to the high flow rate section region, and the second extrusion speed reduction is decreased simultaneously, until the extreme value of the discharge flow rate difference falls back to less than the extreme value of the first flow rate difference; wherein, the second temperature increment is greater than the first temperature increment, and the second extrusion speed reduction is greater than the first extrusion speed reduction.

8. The method according to claim 7, characterized in that, The method further includes: The difference between the metal flow velocities at multiple outlets at adjacent moments is determined as the absolute flow velocity difference; the difference between the metal flow velocities at multiple outlets and the metal flow velocity reference value is determined as the reference flow velocity difference. When the absolute difference in flow rate is greater than the preset absolute difference in flow rate, or when the reference flow rate difference is greater than the preset reference flow rate difference, the first temperature reference value is increased synchronously for the radial preheating zone temperature reference value of the bar stock at different radial positions, and the second temperature reference value is decreased for the axial heating zone temperature reference value at different axial positions.

9. The method according to claim 8, characterized in that, The method further includes: The first temperature reference value is increased synchronously for the radial preheating zone temperature reference value of the bar stock at different radial positions, and the second temperature reference value is decreased for the axial heating zone temperature reference value at different axial positions. After the extrusion speed is reduced by the first extrusion speed reduction, the absolute difference of flow rate is obtained as the adjustment absolute difference of flow rate, and the reference flow rate difference is obtained as the adjustment reference flow rate difference. When the absolute difference in the adjusted flow rate is greater than the preset absolute difference in the flow rate, or when the difference in the adjusted reference flow rate is greater than the preset reference flow rate difference, the preset initial extrusion speed is increased.

10. A car roof rack profile, characterized in that, It is manufactured using the extrusion molding control method for the automobile roof rack profile as described in any one of claims 1 to 9.

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