A closed tube beam mixed material integrally formed instrument transom, mold and preparation method thereof

Abstract

The present application relates to a kind of closed tube beam mixed material integrated forming instrument crossbeam, mould and preparation method thereof, belong to the light weight manufacturing technical field of automotive interior parts, and instrument crossbeam includes closed hollow metal tube beam, vehicle body mounting bracket and functional support;Closed hollow metal tube beam is three-dimensional twisted tube beam, its surface is often warm phosphorus-free silane tao form nanometer organic hybrid film by treatment.Forming instrument crossbeam by using integrated composite mould, adopt constant pressure gas expansion shaping and sectional type gradient pressure injection filling combination, rely on the double-system closed-loop linkage of constant pressure gas expansion gas supply system and sectional type injection constant pressure control system, vehicle body mounting bracket and functional support and closed hollow metal tube beam are realized integrated injection molding.The present application omits additional tooling and drying process, production cost is low, equipment failure rate is small, the size precision of forming product is high, steel-plastic interface bonding strength is excellent, the stability of the mechanical properties of finished product is stable, can satisfy C-NCAP five-star crash load working condition requirement.

Description

Technical Field

[0001] This invention relates to the field of lightweight manufacturing technology for automotive interior parts, specifically to an integrated instrument crossbeam made of a closed tubular beam composite material, a mold, and a method for its preparation. Background Technology

[0002] The instrument panel crossbeam (CCB) is a crucial core safety load-bearing component of a vehicle, primarily responsible for key functions such as integrated installation of the instrument panel, fixed support of the steering column, transfer of vehicle loads, and energy absorption and buffering during collisions. The forming precision, overall structural rigidity, and mechanical stability of this component directly determine the assembly precision of the vehicle's interior and the stability of driving operations, while also profoundly affecting the vehicle's collision safety rating. It is a core component ensuring the passive safety of the entire vehicle and the quality of its interior assembly.

[0003] Currently, most mainstream traditional CCB tube beams in the industry are single straight beam structures. This structure has limited spatial freedom and cannot achieve three-dimensional irregular torsion forming. It is difficult to adapt to the differentiated and complex engine compartment layout and driving space design requirements of different models. It has problems such as poor vehicle adaptability and low degree of universality. As a result, car companies develop a variety of molds, and the cost of each R&D and mass production is high, which is not conducive to platform-based and large-scale production applications.

[0004] Currently, steel-plastic composite CCBs generally employ a separate, dual-mold, independent production process. The core process consists of two steps: first, the metal tube beam is shaped using a water-based medium through an independent internal high-pressure forming mold; second, the shaped metal tube beam is transferred, dried at high temperature, and precisely positioned a second time before being fed into a dedicated injection mold to complete the surface plastic coating. This traditional separate production process has many inherent technical defects, severely restricting improvements in product quality, production efficiency, and safety performance. Specific defects are as follows:

[0005] First, the tooling investment is high, and the product forming accuracy and assembly consistency are poor. Traditional split-type processes require two sets of independent forming molds and corresponding production equipment, doubling the mold development and maintenance costs. Simultaneously, after the metal tube beams are formed, they need to undergo multiple transfers and secondary clamping and positioning. Too many intermediate steps in the production process easily cause surface damage to the tube beams, and multiple positioning will generate cumulative dimensional errors, resulting in large dimensional dispersion in mass-produced CCB products. This makes it difficult to guarantee the subsequent assembly accuracy of the vehicle interior, leading to poor product assembly consistency.

[0006] Secondly, the forming process suffers from poor adaptability, cumbersome procedures, and high energy and environmental costs. Traditional high-pressure forming in water-based media easily leads to corrosion of the inner wall of the steel pipe. Therefore, a high-temperature drying and dehydration process must be added after the steel pipe is formed, which not only increases investment in dedicated drying equipment but also lengthens the production cycle and increases energy consumption. Even though the aluminum tube substrate itself has a natural anodized anti-corrosion layer and is less affected by water-based corrosion, existing production lines still require drying equipment, making it impossible to streamline redundant processes and resulting in a serious waste of equipment resources and energy. Furthermore, traditional pipe beam surface pretreatment commonly uses sandblasting and phosphating processes, which generate large amounts of phosphorus-containing wastewater and heavy metal sludge during production. Pollutant treatment is difficult and environmental governance costs are high, failing to meet the requirements of green production development.

[0007] Secondly, the molding stability of irregularly shaped pre-twisted tubes is poor, resulting in a low product yield. Irregularly shaped CCB tubes have a non-standard structure with uneven thickness. Traditional air-expansion molding processes can only use a single constant pressure for molding, failing to adapt the pressure to accommodate the wall thickness differences in different areas of the tube. During subsequent injection melt lateral extrusion molding, thin-walled areas of the tube are prone to molding defects such as dents, bulges, and deformation, leading to unstable product quality, difficulty in improving yield, and hindering mass production efficiency.

[0008] Furthermore, traditional product structures have safety shortcomings, insufficient process adaptability, and inadequate quality control. Traditional CCB tube beams are mostly smooth structures without mechanical locking mechanisms, and the steel-plastic interface relies solely on adhesive bonding. Under the complex conditions of long-term vehicle vibration and alternating high and low temperatures, the steel-plastic interface is prone to delamination, cracking, and detachment, severely impacting product lifespan and safety. Simultaneously, traditional structures require independent welded steel supports, which are heavy and prone to stress concentration at weld points. Under full-vehicle collision loads, they are susceptible to brittle fracture, failing to reliably perform their safety functions of collision energy absorption and load transfer.

[0009] Finally, traditional manufacturing processes lack online real-time monitoring mechanisms, relying solely on offline sampling inspections to control product quality. This makes it impossible to monitor and correct process deviations in real time, hindering the continuous and stable compliance with the stringent requirements of the C-NCAP five-star crash safety regulations. Furthermore, traditional injection molding processes are only compatible with single modified plastic materials, resulting in a narrow range of material compatibility and making it impossible to achieve mass production adaptation of multiple material systems. This makes it difficult to meet the differentiated performance requirements of different vehicle models and configurations. Summary of the Invention

[0010] Addressing the industry's technical pain points such as high cost of existing split-mold processes, easy corrosion of steel pipes in water-based media, significant pollution from traditional phosphating processes, difficulty in adapting to differences in wall thickness of irregularly shaped pipes with single pressure molding, easy deformation during molding, lack of real-time quality control during molding, easy delamination of steel-plastic interfaces, easy failure of steel welded supports due to collisions, and narrow range of applicable injection molding materials, this invention provides a one-piece molding process for instrument crossbeams made of hybrid materials with closed tube beams, a mold, and its preparation method. It adopts a single set of integrated composite molds, first using nitrogen constant pressure gas expansion for shaping, and then using segmented gradient injection molding pressure compensation. This integrated process enables the one-piece injection molding of hybrid materials for pre-torsion closed tube beam instrument crossbeams (CCB) that are compatible with both steel and aluminum. The product surface undergoes environmentally friendly phosphorus-free pretreatment. Real-time online monitoring and correction of process deviations are performed during the molding process. Under the premise of simplifying the mold structure, this invention completely solves the deformation defects in the molding of irregularly shaped pre-torsion tubes, improving the mechanical properties and mass production stability of the product.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A closed-loop composite material instrument beam is characterized in that the instrument beam comprises a closed hollow metal tube beam, a vehicle body mounting bracket, and a functional bracket.

[0013] The closed hollow metal tube beam is a three-dimensional torsion tube beam with a three-dimensional torsion spatial structure along the X, Y, and Z axes. The surface of the closed hollow metal tube beam has a nano-organic hybrid film. The two vehicle body mounting brackets are respectively located at both ends of the closed hollow metal tube beam, and at least one functional bracket is arranged along the length of the closed hollow metal tube beam. The vehicle body mounting bracket and the functional bracket are integrally injection molded and connected to the closed hollow metal tube beam using glass fiber reinforced composite material.

[0014] Furthermore, the closed hollow metal tube beam has flat covering sections at both ends, and the vehicle body mounting bracket covers the outside of the flat covering sections; the cross-section of the closed hollow metal tube beam is circular, square or elliptical.

[0015] Furthermore, the entire outer surface of the closed hollow metal tube beam is provided with an outer wall knurling structure, and the knurling pattern is continuously arranged in both the axial and circumferential directions along the closed hollow metal tube beam.

[0016] Furthermore, the functional support is provided with a metal insert.

[0017] The present invention also discloses an integrated composite mold for manufacturing the instrument crossbeam described in any one of the above, characterized in that the mold is composed of upper and lower half molds that are locked together, and has a cavity inside; a tube beam cavity is provided in the middle of the cavity along the axial direction, and a plurality of functional support cavities communicating with the tube beam cavity are provided above and below the tube beam cavity; bidirectional sealing nozzles are integrated at both ends of the mold along the axial direction, and the inner port of the bidirectional sealing nozzle faces the tube beam cavity;

[0018] The mold has an axially arranged air supply pipe at the middle of one end, which is connected to the constant pressure air expansion supply system. The air supply pipe is connected to the two bidirectional sealing air nozzles.

[0019] The cavity sidewall is provided with a plurality of injection holes corresponding one-to-one with the functional support cavity. The plurality of injection holes are respectively connected to the main injection pipe of the segmented injection constant pressure control system through branch pipes. The constant pressure air expansion supply system and the segmented injection constant pressure control system interact with each other through an industrial bus. The branch pipe is provided with a melt pressure regulating valve electrically connected to the segmented injection constant pressure control system for controlling the injection pressure of the injection holes.

[0020] An online detection module is embedded on the parting surface of the upper and lower halves of the mold. The online detection module consists of multiple sets of cavity pressure detection modules and multiple sets of laser ranging modules arranged in pairs.

[0021] This invention also discloses a method for preparing an instrument crossbeam integrally molded from a closed-loop tube beam composite material, characterized in that the preparation method is achieved through the integrated composite mold described above, and the steps are as follows:

[0022] S1. Prepare pre-torsional tubular beams;

[0023] According to the layout of the vehicle's engine compartment, the closed metal tube is subjected to three-dimensional torsion shaping along the X, Y, and Z axes to form a pre-torsion tube beam; the outer wall knurling structure is fully distributed on the outer surface of the pre-torsion tube beam, and the surface of the pre-torsion tube beam is pretreated by a room temperature phosphorus-free silane ceramic coating process to generate a nano-organic hybrid film.

[0024] S2, Pre-installed pre-torsional tube beams, metal inserts and mold positioning;

[0025] The pre-torsion tube beam obtained in step S1 is placed in the tube beam cavity in the middle of the mold, and a uniform expansion gap is reserved between it and the inner wall of the tube beam cavity; the bidirectional sealing air nozzles at both ends of the mold seal the pipe openings at both ends of the pre-torsion tube beam in a bidirectional pressing manner, and the two bidirectional sealing air nozzles are connected to the constant pressure air expansion supply system through air supply pipes; multiple metal inserts are pre-installed one by one into the corresponding positioning slots in the cavity of the functional bracket that matches the required functional bracket; after the pre-installation is completed, the mold is closed and locked, and the laser ranging module and cavity pressure detection module corresponding to the functional bracket in the mold are activated to complete the equipment signal docking and parameter initialization, and the equipment enters the real-time monitoring standby state;

[0026] S3. The pre-torsion tube beam is shaped by constant pressure air expansion;

[0027] The constant pressure air expansion supply system supplies dry gas bidirectionally and synchronously into the inner cavity of the pre-torsion tube beam through the gas supply pipe and the two bidirectional sealing nozzles until the pressure inside the pre-torsion tube beam rises to the predetermined constant pressure, and the constant pressure is located in a single constant pressure range throughout the air expansion and shaping process.

[0028] S4, segmented gradient pressure injection filling + dual-system closed-loop linkage

[0029] Under the condition of constant pressure without pressure release and complete shape stabilization of the pre-torsion tube beam cavity, the segmented injection constant pressure control system is activated. Based on the differences in structural wall thickness in different areas of the pre-torsion tube beam and the required functional support, the filling logic of thin-walled low-pressure shaping and thick-walled high-pressure glue filling is adopted to implement zoned differentiated gradient pressure injection filling of glass fiber reinforced composite material in the functional support cavity.

[0030] The constant pressure air expansion supply system and the segmented injection molding constant pressure control system synchronously collect data and perform data interaction once at predetermined time intervals. The constant pressure air expansion supply system collects the pressure inside the pre-torsion tube beam, and the segmented injection molding constant pressure control system collects the injection melt pressure of the functional support cavity and the outer diameter deformation data of the pre-torsion tube beam. The segmented injection molding constant pressure control system dynamically adjusts the injection melt pressure parameters of the functional support cavity in each region according to the outer diameter deformation data and the pressure inside the pre-torsion tube beam, while the constant pressure air expansion supply system maintains the pressure inside the pre-torsion tube beam constant.

[0031] S5. Synchronous pressure holding and cooling of pre-torsion tube beam and functional support with adaptive parameter correction;

[0032] After injection molding and filling, pressure holding and shrinkage compensation are performed; the constant pressure air expansion supply system continuously maintains the constant pressure and shape preservation state of the pre-torsion tube beam cavity; the segmented injection molding constant pressure control system continuously holds pressure and cools according to the preset gradient pressure for a predetermined holding time;

[0033] The built-in laser ranging module and cavity pressure detection module of the mold collect the outer diameter and pressure data of the CCB assembly in real time, identify dimensional deviations, pressure fluctuations and local deformation, and transmit the detection data to the segmented injection constant pressure control system. The segmented injection constant pressure control system compares the detection data with the preset threshold and adjusts the injection pressure parameters of the corresponding area according to the comparison result.

[0034] S6. Staged pressure relief demolding and online finished product performance testing;

[0035] After the plastic melt is completely cooled and solidified, the segmented injection constant pressure control system gradually and smoothly reduces the segmented pressure holding pressure of each functional bracket cavity. The constant pressure air expansion supply system then slowly and uniformly releases the high-pressure gas inside the pre-torsion tube beam. After the air pressure inside and outside the pre-torsion tube beam is completely balanced, the mold is opened, the CCB assembly is taken out, and the instrument crossbeam described in any of the above-mentioned descriptions is obtained.

[0036] During the depressurization process, the laser ranging module scans the overall outline of the CCB assembly, the support wall thickness, and the deformation of the tube beam in real time, while the cavity pressure detection module verifies the bonding pressure of the steel-plastic interface.

[0037] Furthermore, in step S4, the zoned differential gradient pressure injection filling is performed as follows: for thin-walled areas of the tube beam that are curved or have large torsion, a low-pressure slow injection mode is used for filling; for straight thick-walled areas of the tube beam, a high-pressure fast injection mode is used for filling.

[0038] The overall injection molding melt pressure range is controlled at 60~110MPa, and the segmented holding pressure range is controlled at 20~45MPa.

[0039] Furthermore, during the injection molding process in step S4, the constant pressure air expansion supply system transmits the internal pressure of the pre-torsion tube beam to the segmented injection constant pressure control system, and the segmented injection constant pressure control system transmits the outer diameter deformation data of the pre-torsion tube beam to the constant pressure air expansion supply system.

[0040] Further, the pretreatment process in step S1 is as follows: First, the surface of the pre-torsional tube beam is cleaned with a room temperature hydrocarbon degreasing agent for a preset time to thoroughly remove surface oil and oxidized impurities; then, a room temperature silane ceramic film formation treatment is performed for a preset time to generate a nano-organic hybrid film on the metal surface of the pre-torsional tube beam; finally, a room temperature cold air treatment is used for a preset time to complete the drying.

[0041] Furthermore, the gas used in step S3 is nitrogen.

[0042] The beneficial effects of this invention are:

[0043] This invention discloses a closed-loop composite material instrument crossbeam, mold, and its preparation method. It employs an integrated composite mold combining air expansion molding and composite injection molding functions. Through a step-by-step molding logic of constant pressure air expansion molding and segmented gradient pressure injection filling, it achieves the integrated injection molding of a pre-torsional three-dimensional torsion crossbeam and several functional supports. This solves problems such as high cost of existing split-mold processes, easy corrosion of steel pipes in water-based media, significant pollution from traditional phosphating processes, difficulty in adapting to differences in wall thickness of irregularly shaped pipes with single pressure molding, easy deformation during molding, lack of real-time quality control during molding, easy delamination of the steel-plastic interface, easy failure of steel welded supports upon collision, and narrow applicability of injection molding materials. The mold structure of this invention is simple, with low equipment investment and low failure rate. The molded products have high dimensional accuracy, good steel-plastic interface bonding strength, and stable mechanical properties, meeting the C-NCAP five-star collision stiffness, impact resistance, and modal performance requirements, and are suitable for the mass production needs of both fuel-powered and new energy vehicles.

[0044] The mold of this invention integrates a bidirectional sealing nozzle, injection hole, and online detection module, and is equipped with a dual closed-loop linkage system of a constant pressure air expansion supply system and a segmented injection molding constant pressure control system. It eliminates the need for two independent molding dies required by traditional split-type processes. Instead, the tube is pre-shaped in three dimensions using an independent bending fixture outside the mold, eliminating the need for multi-zone hot runners and simplifying the mold's air, oil, and electrical circuit layout. This significantly reduces mold development, processing, and maintenance costs, and results in a low equipment failure rate.

[0045] The entire molding process of this invention is completed step by step within the same set of molds, eliminating the need for pipe beam transfer and secondary clamping, completely eliminating transfer bumps and cumulative positioning errors, significantly improving the dimensional consistency of batch products, and reducing tooling investment by more than 45%.

[0046] To address the uneven wall thickness of the pre-torsional irregular-shaped tube beam, characterized by thin walls in the curved sections and thick walls in the straight sections, this invention employs a segmented gradient pressure compensation process to optimize and compensate for the injection melt pressure. This solves the defects caused by single-pressure air expansion molding. Based on the structural characteristics of different areas of the pre-torsional tube beam, a multi-segment gradient pressure filling logic of "low-pressure shaping for thin walls and high-pressure filling for thick walls" is adopted. By dynamically matching the injection melt pressure of each area, the extrusion deformation defects caused by the difference in wall thickness of the irregular tube are precisely offset. This stabilizes the knurled outer wall of the tube beam and the Z-shaped pre-embedded metal inserts, completely eliminating the problems of depressions, bulges, and deformation in the thin-walled curved sections. This ensures the molding accuracy of the CCB assembly, improves the stability of mass production, and reduces maintenance costs. The air expansion molding process of this invention uses a single constant pressure throughout, continuously stabilizing the pressure until the pre-torsional tube beam's dimensions are completely shaped, stable, and free from springback deformation. This ensures the overall basic shaping accuracy of the tube beam. The mold air circuit structure is extremely simple and requires no pressure adjustment components.

[0047] This invention uses dry constant pressure air expansion to replace water expansion process, with no moisture residue throughout the process. Neither steel nor aluminum pipes will rust, completely solving the problem of steel pipe corrosion. The drying process can be directly eliminated, shortening the production cycle by 25% to 30%, significantly reducing production energy consumption and equipment investment, and is suitable for mass production of steel and aluminum dual-material pipe beams.

[0048] The mold of this invention uses a single universal mainstream runner to complete the overall injection filling. It has a simple structure and strong process controllability. It uniformly uses glass fiber reinforced composite material, which can be adapted to a variety of mainstream modified plastics such as glass fiber reinforced PP and glass fiber reinforced PA6. The material can be flexibly selected according to the vehicle cost and performance requirements, avoiding the defects of poor adaptability of mass production of a single material.

[0049] This invention significantly improves the bond strength between steel and plastic by using a knurled structure throughout the pipe beam and plastic-coated area, relying on physical and mechanical interlocking instead of the traditional single adhesive bonding method. This ensures that the steel-plastic bond surface remains free from delamination and cracking under high and low temperature alternation and long-term vibration conditions. The assembly areas of each functional support are pre-embedded with 1 / 2 scaled-down Z-shaped metal inserts, which, compared to traditional straight inserts, provide stronger coverage, more even stress distribution, and higher assembly accuracy and connection stability.

[0050] This invention employs a room-temperature, phosphorus-free silane coating process to replace the traditional, high-pollution, high-energy-consumption pretreatment process of sandblasting + high-temperature phosphating + high-temperature drying. It requires only three steps: room-temperature degreasing, silane film formation, and natural air drying. This eliminates the need for high-temperature heating, produces no phosphorus-containing wastewater, and generates no heavy metal sludge, significantly improving production efficiency and reducing environmental treatment costs. The nano-organic hybrid film formed on the pipe beam surface further enhances the adhesion between the metal and plastic, improving product durability.

[0051] This invention embeds a laser ranging module and a cavity pressure detection module into the parting surface of the upper and lower molds. Data is collected in real time throughout the entire process of air expansion molding, injection filling, and pressure holding curing. The data is fed back to the constant pressure air expansion supply system and the segmented injection constant pressure control system in real time. Under the dual closed-loop linkage, the injection pressure parameters of each segment are adaptively corrected, reducing the risk of tube beam deformation. Moreover, it does not rely on offline sampling inspection, can provide real-time early warning of molding abnormalities, and controls the mechanical property dispersion of batch products within ±2%, ensuring molding consistency.

[0052] The instrument crossbeam of this invention features a single injection-molded glass fiber reinforced composite material for all functional supports, eliminating steel welding structures, segmented welding stress, and a single-step molding process. This eliminates secondary assembly gaps, and the full-area knurling achieves complete mechanical coupling between the metal and plastic, allowing impact loads to be evenly distributed throughout the assembly without stress concentration points. The entire process is supported by constant nitrogen pressure, eliminating local buckling weak points in the tubing and removing steel welding joints, thus completely eliminating the risk of impact fracture due to welding stress. Simulation and bench testing have verified that the finished product has a bending stiffness ≥8200 N / mm and a first-order torsional mode ≥52 Hz; the maximum deformation in a 50 km / h frontal rigid wall impact is ≤3.2 mm, and the support remains intact without fracture in a 25 km / h side column impact; the strength attenuation rate after 500 hours of high and low temperature vibration is ≤3.5%, far superior to the 12% attenuation rate of traditional processes, and can stably meet the C-NCAP five-star frontal and side impact regulations. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the overall isometric structure of the instrument crossbeam integrally formed from a closed tube beam and hybrid material according to the present invention.

[0054] Figure 2 This is a partially enlarged schematic diagram of the knurling on the outer wall of the closed tube beam in this invention;

[0055] Figure 3 This is a schematic diagram of the integrated molding composite mold and dual-linkage control system of the present invention.

[0056] Among them: 1-closed hollow metal tube beam, 1.1-flat covering section, 2-body mounting bracket, 3-IP bracket, 4-steering column mounting bracket, 5-front bracket, 6-center channel bracket, 7-outer wall knurled structure, 8-metal insert, 9-cavity, 10-expansion gap, 11-pre-torsion tube beam, 12-constant pressure air expansion supply system, 13-segmented injection molding constant pressure control system, 14-laser ranging module, 15-two-way sealing nozzle. Detailed Implementation

[0057] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0058] The terms used in this application, such as top, bottom, left, right, inside, outside, front end, rear end, head, and tail, are based on the orientations or positional relationships shown in the accompanying drawings. Different drawings may result in different positional relationships, therefore they should not be construed as limiting the scope of protection.

[0059] In this invention, the terms "installation," "connection," "interlocking," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, or a connection that allows communication between components. They can also refer to a direct connection or an indirect connection through an intermediate medium. Furthermore, they can refer to the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0060] This embodiment describes an instrument crossbeam integrally molded from a closed-loop tube beam composite material, such as... Figure 1 As shown, the instrument crossbeam includes a closed hollow metal tube beam 1, a body mounting bracket 2, and functional brackets. Two body mounting brackets 2 are respectively installed at both ends of the closed hollow metal tube beam 1. At least one functional bracket is installed along the length of the closed hollow metal tube beam 1.

[0061] In this embodiment, the closed hollow metal tube beam 1 is a three-dimensional torsion tube beam with a three-dimensional torsion space structure of X, Y, and Z axes. It can be, but is not limited to, closed hollow steel tubes or closed hollow aluminum tubes, and its cross-section is a closed structure such as a circle, square, or ellipse.

[0062] like Figure 2 As shown, the closed hollow metal tube beam 1 has flat covered sections 1.1 at both ends. The vehicle body mounting bracket 2 is injection molded and covers the outside of the flat covered sections 1.1. The flat covered sections 1.1 can increase the bonding area between the metal and the plastic, and improve the supporting stiffness of the ends of the closed hollow metal tube beam 1.

[0063] The outer surface of the closed hollow metal tube beam 1 is fully covered with an outer wall knurling structure 7. The knurling pattern is continuously arranged in both the axial and circumferential directions along the closed hollow metal tube beam 1, completely covering the bonding area between the closed hollow metal tube beam 1 and the plastic. This allows the surface of the closed hollow metal tube beam 1 to form a mechanical interlock with the plastic during injection molding, increasing the mechanical bonding friction between the metal matrix and the injection-molded plastic, thereby significantly improving the bonding strength of the metal-plastic composite interface. The outer wall knurling structure 7 can be, but is not limited to, continuous spiral knurling or dot knurling. Preferably, the knurling depth is 0.2~0.25mm to ensure a mechanical locking effect.

[0064] In addition, the surface of the closed hollow metal tube beam 1 has a nano-organic hybrid film to effectively improve the bonding performance between metal and plastic.

[0065] Several functional supports are arranged sequentially and at intervals along the length of the closed hollow metal tube beam 1. These functional supports include the front support 5, IP support 3, central channel support 6, and steering column mounting support 4. Each functional support can be integrally injection molded from various glass fiber reinforced composite materials. The glass fiber reinforced composite materials can be various mainstream modified plastics such as glass fiber reinforced PP and glass fiber reinforced PA6. Each functional support contains a metal insert 8, which is a Z-shaped nut positioning insert with a size reduced to half the traditional specification.

[0066] This embodiment uses an integrated composite mold that combines air expansion molding and composite injection molding functions to fabricate the aforementioned instrument crossbeam as a whole. Figure 3 As shown, the integrated composite mold used consists of upper and lower mold halves that are locked together, and has a cavity 9 inside. A tube beam cavity is provided axially in the middle of cavity 9, and several functional support cavities are provided above and below the tube beam cavity, with the functional support cavities communicating with the tube beam cavity. Two-way sealing air nozzles 15 are integrated at both axial ends of the mold, with their inner ports facing the tube beam cavity, used to cooperate with the pre-torsional tube beam 11 to be injected to form a closed air passage. An air supply pipe is provided axially at one end of cavity 9, connecting to the two-way sealing air nozzles 15 at both ends of the mold. The constant pressure air expansion supply system 12 inputs high-pressure gas at a constant pressure into the pre-torsional tube beam 11 to be injected into the tube beam cavity through the air supply pipe. Multiple independent injection holes, each corresponding to a functional support cavity, are provided on the side wall of cavity 9. These injection holes are connected via branch pipes to the main injection pipe of the segmented injection constant pressure control system 13 located at the other end of cavity 9. The constant pressure air expansion supply system 12 and the segmented injection molding constant pressure control system 13 achieve data interaction through an industrial bus to realize closed-loop linkage.

[0067] A pneumatic control valve is installed on the gas supply pipe to control the gas supply pressure and flow rate. The pneumatic control valve is electrically connected to the constant pressure air expansion supply system 12. The constant pressure air expansion supply system 12 controls the pneumatic control valve to set the gas supply pressure and adjust the gas supply flow rate. A melt pressure regulating valve is installed on the branch pipe to control the injection pressure of the injection hole. The melt pressure regulating valve is electrically connected to the segmented injection molding constant pressure control system 13. The segmented injection molding constant pressure control system 13 controls the melt pressure regulating valve to adjust the injection pressure of the corresponding branch, thereby adjusting the injection melt pressure injected into the mold cavity 9.

[0068] An online detection module is embedded on the parting surface of the upper and lower halves of the integrated composite mold. The online detection module consists of multiple sets of cavity pressure detection modules and multiple sets of laser ranging modules 14 arranged in pairs. Multiple first cavity pressure detection modules are embedded at multiple points around each injection hole and in the functional support cavity to monitor the injection melt pressure in each area in real time and upload it to the segmented injection constant pressure control system 13. In addition, a second cavity pressure detection module is embedded on the parting surface of the tube beam cavity to monitor the pressure inside the pre-torsion tube beam 11 in real time and upload the pressure data to the constant pressure air expansion supply system 12. The constant pressure air expansion supply system 12 exchanges the pressure data with the segmented injection constant pressure control system 13 so that the segmented injection constant pressure control system 13 can dynamically match the zonal injection and segmented pressure holding parameters. Laser ranging modules 14 are arranged in pairs on the parting surfaces of the bending section, thin-walled section, and torsion section of the pre-torsion tube beam 11. They monitor the minute deformation of the outer diameter of the tube beam in real time during the injection filling and pressure holding stages. For example, if the thin-walled section is squeezed inward by the melt (outer diameter shrinks), the segmented injection constant pressure control system 13 will promptly fine-tune the injection pressure and injection speed of the corresponding injection hole. The segmented injection constant pressure control system 13 will feed back the outer diameter deformation data of the tube beam to the constant pressure air expansion supply system 12 through data interaction. The constant pressure air expansion supply system 12 can fine-tune the gas flow rate input into the pre-torsion tube beam 11 according to the outer diameter deformation data of the tube beam so that the pressure inside the pre-torsion tube beam 11 remains constant.

[0069] The instrument beam of this embodiment is prepared using the aforementioned integrated composite mold. The entire preparation process follows an integrated molding logic of "external pre-torsion → constant pressure air expansion and shaping → staged gradient pressure injection molding and encapsulation → synchronous pressure holding and cooling adaptive correction → graded pressure release and demolding + online detection." The entire process requires no separate transport or secondary clamping and positioning, thus producing a closed-loop pipe-beam hybrid material instrument beam in one piece. The specific preparation steps are as follows:

[0070] 1. Fabrication of pre-torsion tubular beams

[0071] The pre-torsion tube beam 11 is a semi-finished product before the final shaping of the closed hollow metal tube beam 1. Its preparation process is as follows: First, a uniformly sized closed metal tube is selected as the base material. The cross-section of the closed metal tube is a closed structure such as circular, square, or elliptical. The tube diameter can be selected, but is not limited to φ40mm~φ42mm, and is uniformly cut to a predetermined length (e.g., 1450mm). Burrs and sharp edges on the cut closed metal tube openings are removed to ensure that the two ends of the closed metal tube are flat and smooth. Second, the closed metal tube is subjected to three-dimensional torsion shaping along the X, Y, and Z axes using an independent bending fixture, processing it into a three-dimensional irregularly shaped pre-torsion tube beam 11 adapted to the layout of the vehicle's engine compartment, thus achieving the pre-forming of the closed hollow metal tube beam 1. Third, an outer wall knurling structure 7 is continuously arranged along the axial and circumferential directions on the outer surface of the pre-torsion tube beam 11. The outer wall knurling structure 7 can be continuous spiral knurling or dotted knurling, with a knurling depth of 0.2~0.25mm. Finally, the surface pretreatment of the pre-torsion tube beam 11 was completed using a room-temperature phosphorus-free silane ceramic coating process.

[0072] The specific pretreatment process is as follows: First, the surface of the pre-torsional tube beam 11 is cleaned with a room-temperature hydrocarbon degreasing agent for a preset treatment time (usually 3-5 minutes, preferably 3 minutes) to thoroughly remove surface oil, oxide impurities, and other contaminants. Then, a room-temperature silane ceramic film formation treatment is performed for a preset treatment time (usually 3-5 minutes, preferably 4 minutes) to generate a nano-organic hybrid film (i.e., a nanoscale organic-inorganic hybrid film) on the metal surface of the pre-torsional tube beam 11, effectively improving the adhesion between the metal and plastic while also providing protection. Finally, drying is completed using room-temperature cold air for a preset time (usually 2-5 minutes, preferably 2 minutes). This pretreatment process requires no high-temperature heating, produces no phosphorus-containing wastewater or heavy metal sludge, is streamlined, environmentally friendly, and effectively improves the interfacial bonding strength between the metal substrate and the plastic.

[0073] 2. Pre-installation of pre-torsion tube beams, metal inserts, and mold positioning.

[0074] Clean the cavity of the integrated composite mold, open the upper and lower mold halves, and precisely place the pre-torsed tube beam 11, which has undergone three-dimensional pre-torsification, knurling, and pretreatment, into the tube beam cavity in the middle of the composite mold. A uniform expansion gap 10 of 0.8~1.5mm is reserved between the outer wall of the pre-torsed tube beam 11 and the inner wall of the tube beam cavity to provide sufficient space for subsequent air expansion deformation of the tube beam. Two bidirectional sealing nozzles 15 seal the ends of the pre-torsed tube beam 11 with a bidirectional tightening method, forming a sealed and pressure-stabilized air passage within the cavity of the pre-torsed tube beam 11. The two bidirectional sealing nozzles 15 are connected to the air supply pipes respectively.

[0075] Multiple U-shaped metal inserts 8, reduced to half the size of traditional ones, are precisely pre-installed one by one into the corresponding positioning slots within the cavity of the functional bracket that matches the required functional bracket. This ensures that the metal inserts 8 are accurately positioned, securely fixed, and free from offset or wobbling, providing a structural foundation for the subsequent one-piece injection molding of the high-strength functional support. After pre-installation, the mold is closed and locked. The laser ranging module 14 and the cavity pressure detection module corresponding to the functional bracket within the mold are activated to complete the equipment signal docking and parameter initialization. The equipment then enters real-time monitoring standby mode.

[0076] 3. The pre-torsion tube beam 11 is shaped by constant pressure air expansion.

[0077] The constant pressure gas expansion supply system 12 is activated, and dry gas is simultaneously input bidirectionally into the inner cavity of the pre-torsion tube beam 11 through the gas delivery pipe and the bidirectional sealing nozzles 15 at both ends of the mold. Gas supply continues until the second cavity pressure detection module detects that the pressure inside the pre-torsion tube beam 11 has risen to the predetermined constant stabilizing pressure, at which point the constant pressure gas expansion supply system 12 stops supplying gas. The gas used in this embodiment is, but is not limited to, nitrogen. The predetermined constant stabilizing pressure is matched according to the material of the sealed metal tube, such as 80~140MPa for steel tubes and 60~90MPa for aluminum tubes. Furthermore, the constant stabilizing pressure during gas expansion and shaping remains within a single constant stabilizing range throughout the entire process.

[0078] This step employs a single, constant pressure stabilization mode throughout the entire process, eliminating the need for segmented or zoned pressure adjustments. The pre-torsion tube beam 11 is supported and shaped as a whole by a uniform and stable single constant pressure stabilization range throughout the pipe, effectively correcting micro-springback and deformation errors after pre-torsion forming. Pressure stabilization continues until the overall shape and spatial configuration of the pre-torsion tube beam 11 are completely stable, achieving a high-precision shaping effect with no deformation, no springback, and consistent dimensions.

[0079] 4. Segmented gradient pressure injection filling + dual-system closed-loop linkage

[0080] Under constant nitrogen pressure without depressurization within the pre-torsion tube beam 11 and with its shape fully stabilized, the segmented injection molding constant pressure control system 13 is activated. Based on the differences in wall thickness across different areas of the pre-torsion tube beam 11 and the required functional supports, a multi-segment gradient pressure filling logic is employed, using low-pressure shaping for thin-walled sections and high-pressure filling for thick-walled sections. This allows for differentiated gradient pressure injection molding filling of the functional support cavity in different zones. For example, for thin-walled areas with bending and large torsion in the tube beam, a low-pressure, slow-speed injection mode is used to fill with glass fiber reinforced composite material, effectively reducing the lateral extrusion load on the plastic melt and avoiding pressure-induced indentation and deformation defects in the thin-walled tube. For straight, thick-walled areas of the tube beam, a high-pressure, fast-injection mode is used to fill with glass fiber reinforced composite material, ensuring rapid melt filling of the cavity and completely eliminating molding defects such as shrinkage marks, material shortages, and voids. In this embodiment, based on the injection requirements of each region of the pre-torsion tube beam 11, the injection pressure of each branch injection hole is preset, that is, the reference pressure of the branch. For example, the reference pressure of the branch corresponding to the thin-walled region of the tube beam bending and large torsion is set to 50~75MPa, and the reference pressure of the branch corresponding to the straight thick-walled region of the tube beam is set to 75~110MPa.

[0081] The overall injection melt pressure range of this gradient pressure injection molding process is controlled at 60~110MPa, and the segmented holding pressure range is controlled at 20~45MPa. During the injection molding process, the constant pressure air supply system 12 and the segmented injection constant pressure control system 13 synchronously collect data at predetermined time intervals and complete a data exchange through the industrial bus. For example, in this embodiment, the two systems synchronously collect data every 10ms. The constant pressure air supply system 12 collects the pressure inside the pre-torsion tube beam 11 in real time through the second cavity pressure detection module, and the segmented injection constant pressure control system 13 collects the real-time injection melt pressure inside the functional support cavity through the first cavity pressure detection module. The laser ranging module 14 collects the deformation data of the outer diameter of the pre-torsion tube beam 11 at the corresponding position in real time, and identifies the deformation trend of the tube being squeezed inward by the melt (i.e., the outer diameter becomes smaller) or squeezed outward (i.e., the outer diameter becomes larger). The constant pressure air supply system 12 and the segmented injection molding constant pressure control system 13 interact with each other. The constant pressure air supply system 12 transmits the internal pressure of the pre-torsion tube beam 11 to the segmented injection molding constant pressure control system 13, and the segmented injection molding constant pressure control system 13 transmits the outer diameter deformation data of the pre-torsion tube beam 11 to the constant pressure air supply system 12. The segmented injection molding constant pressure control system 13 dynamically fine-tunes the injection melt pressure parameters of each functional support cavity based on the outer diameter deformation data and the internal pressure of the pre-torsion tube beam 11.

[0082] For example, when the thin-walled section of the pre-torsion tube beam 11 is detected to show an inward concavity trend, the segmented injection constant pressure control system 13 receives the outer diameter deformation signal and outputs a control signal to the melt pressure regulating valve of the branch pipe in that area: reduce the injection pressure and injection speed of the branch pipe. This reduces the lateral extrusion pressure of the melt, reduces the extrusion load of the melt on the thin-walled outer wall of the pre-torsion tube beam 11, and prevents the tube from concave further inward. Meanwhile, the branch pipes corresponding to the other unaffected thick-walled straight areas continue to maintain the previous high injection pressure and injection speed to ensure that the corresponding functional bracket cavity is fully filled and avoid defects such as material shortage and shrinkage marks. When the cavity pressure detection module detects that the corresponding functional bracket cavity pressure is low, but the outer diameter of the pre-torsion tube beam 11 has not decreased, there is a risk of insufficient filling and shrinkage marks. The segmented injection constant pressure control system 13 outputs a signal: appropriately increase the injection pressure and injection speed of the branch pipe, increase the melt filling flow rate, and ensure that the functional bracket cavity is fully filled. Meanwhile, the segmented injection constant pressure control system 13 continuously reads the outer diameter deformation data detected in real time by the laser ranging module 14. Once the pre-torsion tube beam 11 is detected to show a deformation trend, the injection pressure of the branch pipe is immediately controlled to drop to prevent the pipe from being crushed.

[0083] The constant pressure air expansion supply system 12 adjusts the gas flow rate input into the pre-torsion tube beam 11 according to the outer diameter deformation data, and controls it in coordination with the injection melt pressure to keep the pressure in the pre-torsion tube beam 11 at the preset pressure. This completely offsets the risk of tube deformation caused by the lateral extrusion of the melt, and ensures that the plastic melt completely covers the knurled structure 7 and the pre-embedded metal insert 8 on the outer wall of the tube beam, resulting in full molding and dense and defect-free interface bonding.

[0084] During the injection molding process, the two ends of the pre-torsion tube beam 11 are controlled by air expansion extrusion and injection extrusion in a coordinated manner, and are extruded into a flat covering section 1.1, so that the vehicle body mounting bracket 2 is completely injection molded to cover the outside of the flat covering section 1.1, increasing the bonding area between metal and plastic, and improving the end support stiffness and structural stability.

[0085] 5. Synchronous pressure holding and cooling with adaptive parameter correction for pre-torsion tube beam 11 and functional support.

[0086] After injection molding and filling, the pressure holding and shrinkage compensation stage begins. During this stage, the constant pressure air supply system 12 continuously maintains a constant pressure and shape-preserving state within the pre-torsional tube beam 11. The segmented injection molding constant pressure control system 13 continuously holds pressure and cools according to a preset gradient pressure for a specified duration (e.g., 35-45 seconds), with a preferred duration of 40 seconds. The preset gradient pressure is gradually reduced in three stages: high pressure shrinkage compensation → medium pressure stabilization → low pressure stress relief, to compensate for plastic cooling shrinkage, balance internal stress in the product, and prevent cracking, shrinkage marks, and flash at the gate. Throughout the cooling and solidification stage, the pre-torsional tube beam 11 maintains a constant high-pressure nitrogen support state, fundamentally eliminating molding defects such as thin-walled tube beam cooling springback, local depressions, and bulges, until the plastic melt inside the functional support cavity is completely and uniformly cooled and solidified.

[0087] The built-in laser ranging module 14 and cavity pressure detection module monitor the molding status in real time throughout the process, and collect the outer diameter dimensions of the CCB assembly (such as contour, support wall thickness, tube beam deformation, etc.) and pressure data in real time. It identifies abnormal working conditions such as dimensional deviation, pressure fluctuation, and local deformation, and transmits the detection data to the segmented injection constant pressure control system 13. The segmented injection constant pressure control system 13 automatically fine-tunes the injection pressure parameters of the corresponding area based on the comparison between the detection data and the preset threshold. For example, when the outer radial shrinkage of the thin-walled area of ​​the pre-torsion tube beam 11 reaches the 0.10-0.15mm indentation risk threshold, it is determined that the tube in this area has a tendency to be squeezed inward by the melt. The segmented injection constant pressure control system 13 sends a control signal to the melt pressure regulating valve on the corresponding branch pipe of this area, reducing the injection pressure of this branch pipe by 15-30MPa and the injection speed to 30%-60% of the original set value, thereby reducing the lateral extrusion force of the melt on the pre-torsion tube beam 11. When the cavity pressure detection module detects that the melt pressure in the corresponding cavity is 10-20 MPa lower than the corresponding branch reference pressure, and the laser ranging module 14 detects that the pre-torsion tube beam 11 has no risk of inward deformation, the injection pressure of the branch tube is increased by 8-15 MPa, the injection speed is appropriately increased, and the cavity is fully filled. The segmented injection constant pressure control system 13 realizes closed-loop adaptive correction of the molding process, which greatly improves the molding consistency and dimensional stability of batch products.

[0088] 6. Staged pressure relief demolding and online finished product performance testing

[0089] After the plastic melt in cavity 9 has completely cooled and solidified, a stepped pressure reduction process is used for pressure relief. First, the segmented injection molding constant pressure control system 13 gradually and smoothly reduces the segmented pressure holding pressure of each functional support cavity. Then, the constant pressure air expansion supply system 12 slowly and uniformly releases the high-pressure nitrogen gas inside the pre-torsion tube beam 11. In this embodiment, the internal stress of the pre-torsion tube beam 11 is balanced by the pressure relief method inside and outside the tube, avoiding product deformation caused by instantaneous pressure relief. After the internal and external pressure of the pre-torsion tube beam 11 is completely balanced, the mold is opened and the CCB assembly (i.e., the instrument crossbeam) is removed. The structure of the pre-torsion tube beam 11 after complete shaping in the CCB assembly is the closed hollow metal tube beam 13 of the instrument crossbeam, and the injection-molded parts are functional supports.

[0090] During the depressurization process, the laser ranging module 14 integrated into the mold is used to scan key dimensional parameters such as the overall outline of the CCB assembly, the support wall thickness, and the deformation of the tube beam in real time. This is combined with the cavity pressure detection module to verify the bonding pressure at the steel-plastic interface, quickly determining the product's dimensional qualification rate. After demolding, the finished product is obtained through manual deburring. Mechanical property tests, including bending stiffness, torsional mode, impact resistance, and durability, are conducted through manual sampling. The tests show that the CCB assembly prepared in this embodiment fully meets all load conditions requirements for a C-NCAP five-star crash test. Compared to traditional steel CCBs, the assembly achieves a weight reduction of over 30%, and the production cycle time is shortened by 25% to 30% compared to traditional split-type molding processes. The product batch dimensional dispersion is ≤±2%, demonstrating excellent mass production stability and consistency.

[0091] Although the principles of the present invention have been described in detail above with reference to preferred embodiments, those skilled in the art should understand that the above embodiments are merely illustrative explanations of the implementation of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Any obvious changes, such as equivalent transformations or simple substitutions, based on the technical solutions of the present invention without departing from the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A closed-loop pipe beam integrally molded instrument crossbeam of mixed materials, characterized in that, The instrument crossbeam includes a closed hollow metal tube beam (1), a vehicle body mounting bracket (2), and a functional bracket; The closed hollow metal tube beam (1) is a three-dimensional torsion tube beam with a three-dimensional torsion space structure of X, Y, and Z axes. The surface of the closed hollow metal tube beam (1) has a nano-organic hybrid film. Two vehicle body mounting brackets (2) are respectively located at both ends of the closed hollow metal tube beam (1), and at least one functional bracket is arranged along the length direction of the closed hollow metal tube beam (1). The vehicle body mounting bracket (2) and the functional bracket are integrally injection molded with the closed hollow metal tube beam (1) using glass fiber reinforced composite material.

2. The instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 1, characterized in that, The closed hollow metal tube beam (1) has flat covering sections (1.1) at both ends, and the vehicle body mounting bracket (2) covers the outside of the flat covering sections (1.1); the cross-section of the closed hollow metal tube beam (1) is circular, square or elliptical.

3. The instrument crossbeam integrally formed from a closed tubular beam composite material according to claim 1, characterized in that, The outer surface of the closed hollow metal tube beam (1) is provided with an outer wall knurling structure (7), and the knurling pattern is continuously arranged in both the axial and circumferential directions along the closed hollow metal tube beam (1).

4. The instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 1, characterized in that, The functional support is provided with a metal insert (8).

5. An integrated composite mold for manufacturing the instrument crossbeam according to any one of claims 1 to 4, characterized in that, The mold is composed of upper and lower half molds that are locked together, and has a cavity (9) inside; a tube beam cavity is provided in the middle of the cavity (9) along the axial direction, and several functional support cavities communicating with the tube beam cavity are provided above and below the tube beam cavity; a two-way sealing air nozzle (15) is integrated at both ends of the mold along the axial direction, and the inner port of the two-way sealing air nozzle (15) faces the tube beam cavity; The mold has an axially connected gas supply pipe at one end of the middle, which is connected to the constant pressure gas expansion supply system (12). The gas supply pipe is connected to the two bidirectional sealing gas nozzles (15) pipelines. The cavity (9) has multiple injection holes on its sidewall that correspond one-to-one with the functional support cavity. The multiple injection holes are connected to the main injection pipe of the segmented injection constant pressure control system (13) through branch pipes. The constant pressure air expansion supply system (12) and the segmented injection constant pressure control system (13) interact with each other through an industrial bus. The branch pipe is equipped with a melt pressure regulating valve that is electrically connected to the segmented injection constant pressure control system (13) to control the injection pressure of the injection holes. The upper and lower half of the mold are fitted with an online detection module. The online detection module consists of multiple sets of cavity pressure detection modules and multiple sets of laser ranging modules (14) arranged in pairs.

6. A method for preparing an instrument crossbeam integrally molded from a closed-loop tube beam composite material, characterized in that, The preparation method is achieved using the integrated composite mold described in claim 5, and the steps are as follows: S1. Prepare pre-torsional tubular beams; According to the layout of the vehicle engine compartment, the closed metal tube is subjected to three-dimensional torsion shaping along the X, Y, and Z axes to form a pre-torsion tube beam (11); the outer wall knurling structure (7) is fully distributed on the outer surface of the pre-torsion tube beam (11), and the surface of the pre-torsion tube beam (11) is pretreated by a room temperature phosphorus-free silane ceramic process to generate a nano-organic hybrid film. S2, Pre-installed pre-torsional tube beams, metal inserts and mold positioning; The pre-torsion tube beam (11) obtained in step S1 is placed in the tube beam cavity in the middle of the mold, and a uniform expansion gap (10) is reserved between it and the inner wall of the tube beam cavity; the bidirectional sealing air nozzles (15) at both ends of the mold are sealed to the pipe openings at both ends of the pre-torsion tube beam (11) in a bidirectional pressing manner, and the two bidirectional sealing air nozzles (15) are connected to the constant pressure air expansion supply system (12) through the air supply pipe; multiple metal inserts (8) are pre-installed one by one into the corresponding positioning slots in the cavity of the functional bracket that matches the required functional bracket; after the pre-installation is completed, the mold is closed and locked, and the laser ranging module (14) and cavity pressure detection module corresponding to the functional bracket in the mold are started to complete the equipment signal docking and parameter initialization, and the equipment enters the real-time monitoring standby state; S3, the pre-torsion tube beam (11) is shaped by constant pressure air expansion; The constant pressure gas expansion supply system (12) supplies dry gas bidirectionally and synchronously into the cavity of the pre-torsion tube beam (11) through the gas supply pipe and the two bidirectional sealing gas nozzles (15) until the pressure inside the pre-torsion tube beam (11) rises to the predetermined constant pressure, and the constant pressure is located in a single constant pressure range throughout the entire gas expansion shaping process. S4, segmented gradient pressure injection filling + dual-system closed-loop linkage Under the condition that the inner cavity of the pre-torsion tube beam (11) is under constant pressure and the shape is completely fixed and stable, the segmented injection constant pressure control system (13) is started. According to the difference in structural wall thickness in different areas of the pre-torsion tube beam (11) and the required functional support, the filling logic of thin-walled low-pressure shaping and thick-walled high-pressure glue filling is adopted to implement zoned differential gradient pressure injection filling of glass fiber reinforced composite material in the cavity of the functional support. The constant pressure air expansion supply system (12) and the segmented injection molding constant pressure control system (13) synchronously collect data and perform data interaction at predetermined time intervals. The constant pressure air expansion supply system (12) collects the pressure inside the pre-torsion tube beam (11), and the segmented injection molding constant pressure control system (13) collects the injection melt pressure of the functional support cavity and the outer diameter deformation data of the pre-torsion tube beam (11). The segmented injection molding constant pressure control system (13) dynamically adjusts the injection melt pressure parameters of the functional support cavity in each region according to the outer diameter deformation data and the pressure inside the pre-torsion tube beam (11). The constant pressure air expansion supply system (12) maintains the pressure inside the pre-torsion tube beam (11) unchanged. S5, pre-torsion tube beam (11) and functional support synchronous pressure holding cooling and adaptive parameter correction; After injection molding and filling, pressure holding and shrinkage compensation are performed; the constant pressure air expansion supply system (12) continuously maintains the constant pressure and shape preservation state of the inner cavity of the pre-torsional tube beam (11); the segmented injection molding constant pressure control system (13) continuously holds pressure and cools for a predetermined holding time according to the preset gradient pressure; The laser ranging module (14) built into the mold and the cavity pressure detection module collect the outer diameter and pressure data of the CCB assembly in real time, identify dimensional deviations, pressure fluctuations and local deformations, and transmit the detection data to the segmented injection constant pressure control system (13). The segmented injection constant pressure control system (13) adjusts the injection pressure parameters of the corresponding area according to the comparison between the detection data and the preset threshold. S6. Staged pressure relief demolding and online finished product performance testing; After the plastic melt is completely cooled and solidified, the pressure of each functional bracket cavity is gradually reduced by the segmented injection constant pressure control system (13). Then, the constant pressure air expansion supply system (12) slowly and uniformly releases the high-pressure gas inside the pre-torsion tube beam (11). After the internal and external air pressure of the pre-torsion tube beam (11) is completely balanced, the mold is opened and the CCB assembly is taken out to obtain the instrument beam according to any one of claims 1 to 4. During the depressurization process, the laser ranging module (14) scans the overall outline of the CCB assembly, the wall thickness of the support, and the deformation of the pipe beam in real time, while the cavity pressure detection module verifies the bonding pressure of the steel-plastic interface.

7. The method for preparing the instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 6, characterized in that, In step S4, the zoned differential gradient pressure injection filling is carried out as follows: for thin-walled areas of the tube beam that are curved or have large torsion, a low-pressure slow injection mode is used for filling; for straight thick-walled areas of the tube beam, a high-pressure fast injection mode is used for filling. The overall injection molding melt pressure range is controlled at 60~110MPa, and the segmented holding pressure range is controlled at 20~45MPa.

8. The method for preparing the instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 6, characterized in that, During the injection molding process in step S4, the constant pressure air expansion supply system (12) transmits the internal pressure of the pre-torsion tube beam (11) to the segmented injection constant pressure control system (13), and the segmented injection constant pressure control system (13) transmits the outer diameter deformation data of the pre-torsion tube beam (11) to the constant pressure air expansion supply system (12).

9. The method for preparing the instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 6, characterized in that, The pretreatment process in step S1 is as follows: First, the surface of the pre-torsional tube beam (11) is cleaned with a room temperature hydrocarbon degreasing agent for a preset time to thoroughly remove surface oil and oxidized impurities; then, a room temperature silane ceramic film formation treatment is performed for a preset time to generate a nano-organic hybrid film on the metal surface of the pre-torsional tube beam (11); finally, a room temperature cold air treatment is used for a preset time to complete the drying.

10. The method for preparing the instrument crossbeam integrally molded from a closed tubular beam composite material according to claim 6, characterized in that, The gas used in step S3 is nitrogen.

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