Manufacturing method of vehicle handle fixing assembly

Abstract

The invention provides a manufacturing method of a vehicle handle fixing assembly, and belongs to the technical field of fastener manufacturing. The method comprises: providing a metal wire; sequentially carrying out six cold heading procedures on the metal wire by adopting a multi-station cold heading machine so as to integrally form a blank of the fastener; carrying out thread rolling treatment on the screw rod part to form an external thread; anti-skid textures are formed on the peripheral face of the body part and are of a latticed protruding structure, and the surface roughness Ra of the anti-skid textures is larger than or equal to 1.6 micrometers. The fastener is integrally formed through six cold heading procedures, thread rolling and high-roughness anti-skid texture treatment are combined, and integrated manufacturing of the vehicle handle fixing assembly with high strength, high precision, easy assembly and good holding anti-skid performance is achieved.

Description

Technical Field

[0001] This application belongs to the field of fastener manufacturing technology, specifically relating to a method for manufacturing a vehicle handle fixing component. Background Technology

[0002] In vehicle interior systems, door handles are frequently touched functional components, and the reliability of their installation structure and assembly efficiency directly affect the overall vehicle quality and user experience. Traditional door handle assemblies lack dedicated drive structures for their fasteners, requiring non-standard tools for installation or after-sales maintenance. This is inconvenient and easily damages surrounding surfaces, severely impacting production efficiency and customer satisfaction.

[0003] In addition, traditional manufacturing processes such as machining or step-by-step stamping are difficult to efficiently form a complex fastening structure that combines internal drive holes, external anti-slip textures and high-strength threads in one piece, resulting in high costs and poor consistency. Summary of the Invention

[0004] To address at least one of the technical problems existing in the background art, this application provides a method for manufacturing vehicle handle fixing components. The fastener is integrally formed through six cold forging processes, and combined with thread rolling and high-roughness anti-slip texture treatment, thereby achieving integrated manufacturing of vehicle handle fixing components with high strength, high precision, easy assembly and good grip and anti-slip performance.

[0005] The technical solution adopted in this application is as follows: This application provides a method for manufacturing a vehicle handle fixing component. The handle fixing component includes an integrally formed fastener. The fastener includes a cover portion, a body portion, and a screw portion in sequence along the axial direction. The body portion is provided with a quincunx-shaped drive hole that extends through the screw portion along the axial direction. The outer peripheral surface of the body portion is provided with an anti-slip texture. The method for manufacturing the vehicle handle fixing component includes: S1. Provide metal wire; S2. The metal wire is subjected to six cold heading processes sequentially using a multi-station cold heading machine to integrally form the blank of the fastener, wherein: First step: Cut the metal wire and use a punch to cooperate with the strong main mold to initially form the cover part; The second step: the outer contour and internal cavity of the cover are pre-formed by using a four-cavity punch die in conjunction with a head-shaped through-hole main die; The third process: the material is compressed through the stepped through-hole main mold to form the transition section between the main body and the screw part; Fourth step: Form a chamfer or rounded corner at the end of the screw section; Fifth step: By engaging the stretching punch with the chamfering main die, a plum blossom-shaped drive hole is axially stretched inside the body. Sixth step: Complete the overall shape finishing to obtain an integral blank having the cover part, body part and screw part; S3. Perform thread rolling on the screw section to form an external thread; S4. An anti-slip texture is formed on the outer peripheral surface of the main body. The anti-slip texture is a grid-like raised structure with a surface roughness Ra≥1.6μm.

[0006] According to the vehicle handle fixing component manufacturing method provided in this application embodiment, a multi-station cold forging process is used to perform six precision cold forging processes on the metal wire, achieving integrated molding of the cover, body, and screw. This not only significantly reduces the number of parts and subsequent assembly steps but also effectively improves the overall structural strength and dimensional consistency, avoiding reliability issues caused by loose connections or detachment of the decorative cover in traditional split structures. In the fifth process, a plum blossom-shaped drive hole is axially stretched inside the body, giving the fastener a dedicated drive interface for easy installation or removal using standard tools, significantly improving production efficiency and after-sales maintenance convenience. The screw section undergoes thread rolling to form a high-precision external thread, ensuring reliable engagement with the mounting holes on the vehicle body and enhancing connection stability. Simultaneously, a grid-like raised anti-slip texture formed on the outer circumference of the main body, with a surface roughness Ra≥1.6μm, effectively increases friction when the user grips it, preventing slippage even in complex conditions such as wetness, sweat, or when wearing gloves, balancing safety and human-machine interaction. Furthermore, the entire manufacturing process is based on cold heading, resulting in high material utilization, no cutting waste, and no need for high-temperature heat treatment, making it energy-saving and environmentally friendly, suitable for mass production and high efficiency, thus significantly reducing manufacturing costs while ensuring high performance.

[0007] According to one embodiment of this application, the metal wire is carbon steel, stainless steel or alloy steel, and has a tensile strength ≥800MPa after cold heading.

[0008] According to one embodiment of this application, the cross-section of the plum blossom-shaped driving hole is a regular hexagon, a regular dodecagon, or a composite plum blossom shape.

[0009] According to one embodiment of this application, the formation of the anti-slip texture on the outer peripheral surface of the body portion specifically includes: Mechanical knurling on a lathe using double-wheel cross-knurling wheels creates a diamond or straight-lined grid; or... Using fiber laser engraving equipment, a mesh microstructure with a depth of 0.05–0.15 mm is ablated on the surface at a power of 20–50 W and a frequency of 20–50 kHz; or, Through a chemical etching process, the particles are immersed in an acidic etching solution for 5–15 seconds to form randomly distributed protruding particles; or, Electrical discharge machining is used to generate a micron-scale bump array on the outer periphery of the body.

[0010] According to one embodiment of this application, the method further includes: The cover plate is assembled to the top of the cover portion of the fastener. The cover plate is provided with a second plum blossom-shaped drive hole coaxial with the plum blossom-shaped drive hole, and the entrance of the second plum blossom-shaped drive hole is provided with a slope of 15°–45° or a rounded corner with a radius of 0.3–1.0 mm.

[0011] According to one embodiment of this application, the multi-station cold heading machine is a DBP-105S type six-station automatic cold heading machine.

[0012] According to one embodiment of this application, in the fifth step, the front end of the stretching punch is provided with a guide cone surface with a cone angle of 30°–60°.

[0013] According to one embodiment of this application, after the sixth process is completed, the blank is subjected to stress-relief annealing treatment at a temperature of 400–550°C and a holding time of 10–30 minutes.

[0014] According to one embodiment of this application, after the screw portion is subjected to thread rolling treatment, the method further includes: The external thread is tested with a thread go / no-go gauge, and the thread pitch diameter tolerance grade is not less than 6g.

[0015] According to one embodiment of this application, an elastic fastening washer is fitted onto the external thread of the screw portion, and the fastener as a whole is surface treated; The surface treatment includes any of the following methods: Electroplated zinc-nickel alloy, with a coating thickness of 8–15 μm, and a salt spray corrosion resistance of ≥500 hours; Matte black Dacromet coating, with a coating thickness of 6–12 μm; or Physical vapor deposition forms TiN or CrN decorative wear-resistant films with a film hardness ≥1500HV. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 A schematic flowchart illustrating the manufacturing method of the vehicle handle fixing component provided in this application embodiment; Figure 2 An exploded view of the vehicle handle fixing assembly provided in an embodiment of this application; Figure 3 This is a cross-sectional view of the vehicle handle fixing assembly provided in an embodiment of this application.

[0017] in, 11. Fastener; 111. Cover part; 112. Body part; 1121. Plum blossom-shaped drive hole; 1122. Anti-slip texture; 113. Screw part; 12. Cover plate; 121. Second plum blossom-shaped drive hole; 13. Elastic fastening gasket. Detailed Implementation

[0018] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0019] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0020] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0023] like Figures 1 to 3 As shown, this application provides a method for manufacturing a vehicle handle fixing component. The handle fixing component includes an integrally formed fastener 11. The fastener 11 includes a cover portion 111, a body portion 112 and a screw portion 113 in sequence along the axial direction. The body portion 112 is provided with a plum blossom-shaped drive hole 1121 that extends through to the screw portion 113 along the axial direction. The outer peripheral surface of the body portion 112 is provided with an anti-slip texture 1122. The manufacturing method of vehicle handle fixing components includes: S1. Provide metal wire.

[0024] S2. A multi-station cold heading machine is used to perform six cold heading processes on the metal wire in sequence to form a blank of fastener 11 in one piece, wherein: First step: Cut the metal wire and use a punch to cooperate with the main mold to initially form the cover part 111.

[0025] The second process involves using a four-cavity punch die in conjunction with a head-shaped through-hole main die to pre-form the outer contour and internal cavity of the cover part 111.

[0026] The third process involves compressing the material through the stepped through-hole main mold to form the transition section between the main body 112 and the screw part 113.

[0027] Fourth step: Form a chamfer or rounded corner at the end of the screw section 113.

[0028] Fifth step: By using a stretching punch to cooperate with a chamfered main die, a plum blossom-shaped drive hole 1121 is axially stretched inside the body 112.

[0029] The sixth step: complete the overall shape finishing to obtain an integral blank with a cover part 111, a body part 112 and a screw part 113.

[0030] S3. Perform thread rolling on the screw section 113 to form an external thread.

[0031] S4. An anti-slip texture 1122 is formed on the outer peripheral surface of the body 112. The anti-slip texture 1122 is a grid-like raised structure with a surface roughness Ra≥1.6μm.

[0032] Specifically, regarding the handle fixing assembly in this application embodiment, the fastener 11 is designed as an integral structure comprising a cover portion 111, a body portion 112, and a screw portion 113. A quincunx-shaped drive hole 1121 extending axially to the screw portion 113 is provided inside the body portion 112, allowing a quincunx bit tool to be directly inserted from the cover plate 12 side during installation or disassembly. Torque is applied to the entire fastener 11 through this drive hole, thereby achieving reliable connection or separation from the vehicle body. Simultaneously, the anti-slip texture 1122 on the outer circumference of the body portion 112, although not involved in the threaded connection, effectively increases the friction between the user's hand and the surrounding area of ​​the handle body during handle gripping, significantly improving operational stability and safety, especially under conditions of sweaty, wet, or gloved hands. On the one hand, the through-type plum blossom-shaped drive hole 1121 is integrated inside the fastener 11 body, avoiding the problems of unreliable torque transmission or easy damage to the cover caused by setting the drive structure only on the decorative cover in the traditional solution. It realizes the functional separation of "true fastening and false decoration", improving assembly efficiency and structural reliability. On the other hand, the anti-slip texture 1122 on the outer periphery of the body 112 serves as a functional surface treatment, which optimizes the human-computer interaction experience and enhances the practicality and quality of the product without adding extra parts.

[0033] First, in step S1, metal wire of suitable material and diameter is provided as the basic raw material for subsequent cold heading. Entering the core forming stage S2, a multi-station cold heading machine sequentially performs six cold heading processes on the metal wire: The first process completes the fixed-length cutting of the wire, and uses the combined action of the punch and the strong-binding main die to initially upset the basic shape of the cover part 111; the second process, with the cooperation of the four-cavity punch and the head-shaped through-hole main die, further precisely pre-forms the external contour and internal cavity structure of the cover part 111, laying the foundation for subsequent assembly or appearance requirements; the third process uses the stepped through-hole main die to axially compress the material, causing the metal to flow and forming a smooth transition section between the body part 112 and the screw part 113, ensuring structural strength and... The stress distribution is uniform; the fourth process is to process a chamfer or rounded corner at the end of the screw part 113 to facilitate subsequent thread rolling and smooth screwing into the threaded hole during installation, avoiding seizing damage; the fifth process is the key functional forming step, in which a plum blossom-shaped drive hole 1121 is stretched axially inside the body part 112 by the cooperation of the stretching punch and the chamfering main die. This structure can be matched with special tools to achieve efficient and reliable tightening operation; the sixth process is to refine the overall blank shape, eliminate burrs, correct dimensional deviations, and finally obtain an integrated fastener 11 blank with a complete cover part 111, body part 112 and screw part 113. Subsequently, in step S3, the screw portion 113 undergoes thread rolling to form a high-precision, high-strength external thread on its outer surface, ensuring a secure connection with the vehicle body mounting location. Finally, in step S4, a grid-like raised anti-slip texture 1122 is machined on the outer peripheral surface of the body portion 112, and its surface roughness Ra is controlled to be ≥1.6μm, significantly improving the friction and operating comfort when the user holds the grip and effectively preventing slippage. The entire manufacturing process is highly integrated, requiring no welding or assembly, and combining high efficiency and high consistency.

[0034] According to the vehicle handle fixing component manufacturing method provided in this application embodiment, a multi-station cold forging process is used to perform six precision cold forging processes on the metal wire, realizing the integrated molding of the cover part 111, the body part 112, and the screw part 113. This not only significantly reduces the number of parts and subsequent assembly steps, but also effectively improves the overall structural strength and dimensional consistency, avoiding reliability problems caused by loose connections or detachment of decorative covers in traditional split structures. In the fifth process, a plum blossom-shaped drive hole 1121 is axially stretched in the body part 112, giving the fastener 11 a dedicated drive interface, which facilitates quick installation or removal using standard tools, significantly improving production efficiency and after-sales service. Convenience of maintenance: The screw part 113 is formed with high-precision external threads through thread rolling, ensuring reliable engagement with the mounting holes on the vehicle body and enhancing connection stability; at the same time, the grid-like raised anti-slip texture 1122 formed on the outer peripheral surface of the body part 112 has a surface roughness Ra≥1.6μm, which effectively improves the friction when the user holds it, preventing slippage even in complex working conditions such as wetness, sweat, or wearing gloves, taking into account both safety and human-machine interaction experience; in addition, the entire manufacturing process is based on cold heading, which has high material utilization, no cutting waste, and no need for high-temperature heat treatment, making it energy-saving and environmentally friendly, suitable for mass production and high efficiency, thereby significantly reducing manufacturing costs while ensuring high performance.

[0035] In some embodiments of this application, the metal wire is carbon steel, stainless steel, or alloy steel, with a tensile strength ≥800MPa after cold heading. These materials possess excellent cold heading performance and mechanical strength, capable of withstanding plastic deformation at high strain rates without cracking or defects during multi-station cold heading. After being integrally formed through six cold heading processes, the internal grains of the fastener 11 are refined and densely arranged along the deformation direction, significantly improving the overall mechanical properties of the material. This ensures that the tensile strength of the final fastener 11 blank is not less than 800MPa, meeting the stringent requirements for high strength and high reliability of vehicle interior components. Simultaneously, this strength level ensures that the fastener 11 can effectively resist vibration, impact, and repeated gripping loads during long-term use, preventing breakage or plastic deformation, thereby guaranteeing the safety and durability of the handle assembly.

[0036] In addition, depending on the specific application environment (such as corrosion protection requirements or lightweight requirements), stainless steel or high-strength alloy steel can be flexibly selected to balance performance and cost.

[0037] In some embodiments of this application, the cross-section of the plum blossom-shaped drive hole 1121 is a regular hexagon, a regular dodecagon, or a composite plum blossom shape. This design significantly improves the contact area and engagement stability between the tool and the drive hole while ensuring high torque transmission capability. Compared to traditional slotted or cross-grooved structures, the aforementioned polygonal or composite plum blossom-shaped cross-sections can effectively disperse stress concentrations generated during tightening or disassembly, reducing the risk of stripping, wear, or tool slippage. Among them, the regular hexagonal structure is easy to use with standard Allen wrenches, offering strong versatility; the regular dodecagon provides a denser force distribution point, suitable for scenarios with limited space but requiring frequent operation; and the composite plum blossom shape combines high torsional resistance with anti-misoperation characteristics, further improving assembly accuracy and reliability.

[0038] The drive hole is integrally formed inside the body 112 by cold heading and stretching process, eliminating the need for subsequent machining, which ensures dimensional consistency and improves production efficiency.

[0039] like Figures 2 to 3 As shown, in some embodiments of this application, an anti-slip texture 1122 is formed on the outer peripheral surface of the body portion 112, specifically: Mechanical knurling on a lathe using double-wheel cross-knurling wheels creates a diamond or straight-lined grid; or... Using fiber laser engraving equipment, a mesh microstructure with a depth of 0.05–0.15 mm is ablated on the surface at a power of 20–50 W and a frequency of 20–50 kHz; or, Through a chemical etching process, the particles are immersed in an acidic etching solution for 5–15 seconds to form randomly distributed protruding particles; or, Electrical discharge machining is used to generate a micron-scale bump array on the outer periphery of the body 112.

[0040] Mechanical roll forming: Mechanical roll forming on a lathe using double-wheel cross knurling wheels can create diamond or straight-line grid patterns. This method is suitable for most metal materials, and the resulting texture is not only aesthetically pleasing but also provides excellent anti-slip properties.

[0041] Laser engraving: Using fiber laser engraving equipment, a mesh microstructure with a depth of 0.05–0.15 mm is ablated onto the surface under specific parameters (power 20–50W, frequency 20–50kHz). Laser engraving can provide high-precision patterns and text markings, and has a small heat-affected zone on the material, making it suitable for fine processing.

[0042] Chemical etching: This process involves immersing the sample in an acidic etching solution for 5–15 seconds to create randomly distributed raised particles. This method is suitable for applications requiring large-area processing and is relatively low-cost.

[0043] Electrical Discharge Machining (EDM): Using EDM technology, a micron-scale bump array is generated on the outer periphery of the body 112 by electrical discharge. This method is particularly suitable for materials such as cemented carbide that are difficult to machine with traditional cutting tools, and can produce a surface structure with good wear resistance and strong corrosion resistance.

[0044] like Figures 2 to 3 As shown, in some embodiments of this application, the method further includes: The cover plate 12 is assembled to the top of the cover portion 111 of the fastener 11. The cover plate 12 is provided with a second plum blossom-shaped drive hole 121 coaxial with the plum blossom-shaped drive hole 1121, and the entrance of the second plum blossom-shaped drive hole 121 is provided with a slope of 15°–45° or a rounded corner with a radius of 0.3–1.0 mm.

[0045] The cover plate 12 is provided with a second quincunx-shaped drive hole 121 that is coaxially aligned with the quincunx-shaped drive hole 1121 inside the fastener 11. This ensures that during installation or disassembly, the drive tool can pass through the second quincunx-shaped drive hole 121 on the cover plate 12 in sequence and be accurately embedded in the main drive hole inside the fastener 11 body, thereby achieving smooth and reliable torque transmission.

[0046] To improve the tolerance and ease of operation of tool insertion, the entrance of the second plum blossom-shaped drive hole 121 is specially designed with a guide slope of 15°–45° or a rounded corner structure with a radius of 0.3–1.0mm, which effectively reduces the risk of tool jamming, edge scratching or drive tooth wear caused by assembly deviation or hand tremors.

[0047] This design not only optimizes the human-computer interaction experience, but also avoids efficiency losses or component damage caused by alignment difficulties in high-frequency maintenance or emergency disassembly scenarios.

[0048] When using tools such as Phillips screwdriver bits to install or remove the handle fixing components, the front end of the tool first contacts the second Phillips-shaped drive hole 121 on the cover plate 12. Since the inlet is provided with a beveled or rounded transition structure, the end of the tool can be naturally guided into the hole, avoiding jamming, slippage or edge bumping caused by misalignment or tilting of the operating angle.

[0049] On the one hand, it significantly improves the smoothness and fault tolerance of tool insertion, especially in confined spaces or in-vehicle assembly environments with limited visibility, effectively reducing operational difficulty and improving assembly and maintenance efficiency; on the other hand, the beveled or rounded transition eliminates sharp edges or burrs at the drive hole entrance, not only protecting the tool edge from damage, but also preventing scratches on surrounding trim or user hands during frequent operations, thus enhancing the product's safety and refinement.

[0050] For example, at the entrance of the second quincunx-shaped drive hole 121 on the cover plate 12, a guide slope angle of 30° or a fillet with a radius of 0.6 mm can be selected. This effectively guides the tool to be inserted smoothly while taking into account both processing feasibility and structural strength, making it suitable for most assembly scenarios.

[0051] In some embodiments of this application, the multi-station cold heading machine is a DBP-105S type six-station automatic cold heading machine.

[0052] This equipment features high-precision feeding, stable stamping and forming capabilities, and efficient continuous operation, making it suitable for cold heading of metal wires with diameters ranging from Φ3 to Φ10mm. Its six stations can simultaneously complete processes such as cutting, pre-forming, compression, chamfering, internal hole stretching, and finishing, highly matching the six cold heading steps described in this application. The DBP-105S cold heading machine is equipped with a servo control system and a precision mold guiding mechanism, ensuring that the positioning error between each process is less than ±0.02mm, thereby guaranteeing the dimensional consistency and internal structural integrity of the fastener blank 11. It is particularly suitable for the integrated high-precision forming of complex geometric features such as the quincunx-shaped drive hole 1121, the transition section contour, and the cover cavity 111. Furthermore, this model has excellent process repeatability and production cycle time (up to 80–120 pieces per minute), meeting the needs of high-volume, high-quality, and low-cost manufacturing of automotive parts.

[0053] In some embodiments of this application, in the fifth step, the front end of the stretching punch is provided with a guide cone surface with a cone angle of 30°–60°.

[0054] For example, a midpoint of 45° can be selected as a typical implementation parameter. The function of this guide cone is to achieve smooth introduction when the punch enters the pre-drilled hole in the body part 112, reducing the off-center load and stress concentration in the initial contact stage, and avoiding material tearing or hole wall collapse. At the same time, a reasonable cone angle design helps the metal flow uniformly during axial tension, thereby ensuring that the plum blossom-shaped drive hole 1121 has a clear outline, stable dimensions, smooth inner wall, and no forming defects such as folds or microcracks. If the cone angle is too small (e.g., less than 30°), the guiding effect is insufficient, which can easily lead to punch skew; if the cone angle is too large (e.g., more than 60°), it will weaken the strength of the punch tip and may cause local over-extrusion, affecting the hole shape accuracy. Therefore, controlling the cone angle within the range of 30°–60° balances forming reliability, die life, and part quality.

[0055] In some embodiments of this application, after the sixth process is completed, the blank is subjected to stress-relief annealing treatment at a temperature of 400–550°C and a holding time of 10–30 minutes.

[0056] After the sixth process is completed and the integral fastener blank 11 is obtained, in order to further improve its dimensional stability and mechanical property consistency, this method also includes stress-relieving annealing of the blank. Specifically, the blank is placed in a controlled atmosphere heat treatment furnace and held at a temperature range of 400–550°C for 10–30 minutes (for example, typical parameters can be selected: annealing temperature 480°C, holding time 20 minutes), and then cooled in the furnace or air-cooled to room temperature.

[0057] This heat treatment process aims to effectively eliminate residual stress accumulated within the material due to severe plastic deformation during cold heading, preventing micro-deformation, cracking, or dimensional drift during subsequent thread rolling, assembly, or use. Simultaneously, because the annealing temperature is much lower than the material's recrystallization temperature (especially suitable for carbon steel or low-alloy steel), it improves the material's toughness and fatigue resistance without significantly reducing the high strength (tensile strength ≥800MPa) resulting from work hardening, ensuring that fastener 11 maintains structural reliability and functional durability under vehicle vibration, impact, and long-term holding loads.

[0058] In some embodiments of this application, after the screw portion 113 is thread-rolled, the following steps are also included: External threads are inspected using thread go / no-go gauges, and the thread pitch diameter tolerance grade is not less than 6g.

[0059] After the thread rolling process is completed on the screw section 113, to further ensure the interchangeability, assembly reliability, and fastening performance of the threaded connection, this method also includes thread go / no-go gauge testing of the formed external thread. Specifically, thread gauges conforming to national standards (such as GB / T 197 or ISO 965) are used for inspection: the "go gauge" should be able to smoothly screw into the entire effective length of the thread, while the "no-go gauge" should not screw in more than two turns, thus determining whether the thread is qualified. This test requires that the thread pitch diameter tolerance grade be no less than 6g (i.e., meeting 6g or a more precise tolerance zone, such as 4g, 5g, etc.), where "6g" is a commonly used medium precision grade for external threads, suitable for automotive structural components where both strength and assemblability are required. Through this test, the dimensional deviation, thread angle consistency, and surface integrity of the thread can be effectively controlled, avoiding problems such as assembly difficulties and seizing due to overtight threads, or insufficient preload and loose connections due to overly loose threads, thereby ensuring the reliable engagement and long-term stability of the handle fixing assembly with the body mounting holes throughout the vehicle's life cycle.

[0060] like Figures 2 to 3 As shown, in some embodiments of this application, an elastic fastening washer 13 is fitted onto the external thread of the screw portion 113, and the fastener 11 as a whole is surface treated. Surface treatment includes any of the following methods: Electroplated zinc-nickel alloy, with a coating thickness of 8–15 μm, and a salt spray corrosion resistance of ≥500 hours; Matte black Dacromet coating, with a coating thickness of 6–12 μm; or Physical vapor deposition forms TiN or CrN decorative wear-resistant films with a film hardness ≥1500HV.

[0061] When the fastener 11 is screwed into the mounting hole on the vehicle body through the screw portion 113 and tightened, the elastic fastening washer 13 is compressed between the end of the screw portion 113 and the vehicle body. Its elastic deformation capacity absorbs assembly tolerances and compensates for unevenness of the contact surface, and generates a continuous reverse elastic force under the preload. This elastic force not only enhances the axial clamping effect of the connection but also effectively suppresses the loosening tendency caused by vibration, impact, or thermal expansion and contraction during vehicle operation.

[0062] On the one hand, it significantly improves the connection reliability and durability of the handle fixing components under dynamic load environments, avoiding the risk of abnormal noise, shaking, or even detachment caused by loosening. On the other hand, the elastic buffering effect can reduce stress concentration on the body sheet metal or plastic base due to rigid contact, preventing cracking or wear in the installation area, which is especially suitable for applications using lightweight body materials (such as aluminum alloys or engineering plastics). In addition, this gasket can also play a certain role in sealing and vibration isolation, further optimizing the overall vehicle NVH performance and user-perceived quality.

[0063] Firstly, electroplated zinc-nickel alloy with a coating thickness controlled at 8–15 μm has excellent corrosion resistance. Under neutral salt spray test conditions, the corrosion resistance can reach ≥500 hours, making it suitable for vehicle interiors or semi-exposed areas with high corrosion resistance requirements, while maintaining good conductivity and compatibility with subsequent coatings. Secondly, it adopts a matte black Dacromet coating with a thickness of 6–12 μm. This chromium-free or low-chromium zinc-aluminum coating not only has excellent salt spray resistance and heat aging resistance, but also gives the fastener 11 a uniform matte black appearance, which meets the low-key and exquisite aesthetic requirements of high-end models for interior parts, and has no risk of hydrogen embrittlement, making it particularly suitable for high-strength fastener 11. Third, a TiN (titanium nitride) or CrN (chromium nitride) decorative wear-resistant film is formed on the surface of fastener 11 through physical vapor deposition. The film has a hardness of up to ≥1500 HV and combines high wear resistance, chemical inertness and metallic luster.

[0064] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0065] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0066] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for manufacturing a vehicle handle fixing component, characterized in that, The handle fixing assembly includes an integrally formed fastener, which includes a cover, a body and a screw in sequence along the axial direction. The body is provided with a quincunx-shaped drive hole that extends through the screw in the axial direction, and the outer peripheral surface of the body is provided with an anti-slip texture. The method for manufacturing the vehicle handle fixing component includes: S1. Provide metal wire; S2. The metal wire is subjected to six cold heading processes sequentially using a multi-station cold heading machine to integrally form the blank of the fastener, wherein: First step: Cut the metal wire and use a punch to cooperate with the strong main mold to initially form the cover part; The second step: the outer contour and internal cavity of the cover are pre-formed by using a four-cavity punch die in conjunction with a head-shaped through-hole main die; The third process: the material is compressed through the stepped through-hole main mold to form the transition section between the main body and the screw part; Fourth step: Form a chamfer or rounded corner at the end of the screw section; Fifth step: By engaging the stretching punch with the chamfering main die, a plum blossom-shaped drive hole is axially stretched inside the body. Sixth step: Complete the overall shape finishing to obtain an integral blank having the cover part, body part and screw part; S3. Perform thread rolling on the screw section to form an external thread; S4. An anti-slip texture is formed on the outer peripheral surface of the main body. The anti-slip texture is a grid-like raised structure with a surface roughness Ra≥1.6μm.

2. The method for manufacturing a vehicle handle fixing component according to claim 1, characterized in that, The metal wire is made of carbon steel, stainless steel or alloy steel, and has a tensile strength ≥800MPa after cold heading.

3. The method for manufacturing a vehicle handle fixing component according to claim 1, characterized in that, The cross-section of the plum blossom-shaped driving hole is a regular hexagon, a regular dodecagon, or a composite plum blossom shape.

4. The method for manufacturing a vehicle handle fixing assembly according to claim 1, characterized in that, The anti-slip texture formed on the outer peripheral surface of the body is specifically as follows: Mechanical knurling on a lathe using double-wheel cross-knurling wheels creates a diamond or straight-lined grid; or... Using fiber laser engraving equipment, a mesh microstructure with a depth of 0.05–0.15 mm is ablated on the surface at a power of 20–50 W and a frequency of 20–50 kHz; or, Through a chemical etching process, the particles are immersed in an acidic etching solution for 5–15 seconds to form randomly distributed protruding particles; or, Electrical discharge machining is used to generate a micron-scale bump array on the outer periphery of the body.

5. The method for manufacturing a vehicle handle fixing assembly according to any one of claims 1 to 4, characterized in that, The method also includes: The cover plate is assembled to the top of the cover portion of the fastener. The cover plate is provided with a second plum blossom-shaped drive hole coaxial with the plum blossom-shaped drive hole, and the entrance of the second plum blossom-shaped drive hole is provided with a slope of 15°–45° or a rounded corner with a radius of 0.3–1.0 mm.

6. The method for manufacturing a vehicle handle fixing assembly according to claim 1, characterized in that, The multi-station cold heading machine is a DBP-105S type six-station automatic cold heading machine.

7. The method for manufacturing a vehicle handle fixing component according to claim 1, characterized in that, In the fifth step, the front end of the stretching punch is provided with a guide cone surface with a cone angle of 30°–60°.

8. The method for manufacturing a vehicle handle fixing component according to claim 1, characterized in that, After the sixth process is completed, the blank is subjected to stress-relieving annealing treatment at a temperature of 400–550℃ and a holding time of 10–30 minutes.

9. The method for manufacturing a vehicle handle fixing component according to claim 1, characterized in that, After the screw section is thread-rolled, the process further includes: The external thread is tested with a thread go / no-go gauge, and the thread pitch diameter tolerance grade is not less than 6g.

10. The method for manufacturing a vehicle handle fixing assembly according to claim 1, characterized in that, An elastic fastening washer is fitted onto the external thread of the screw section, and the entire fastener is surface treated. The surface treatment includes any of the following methods: Electroplated zinc-nickel alloy, with a coating thickness of 8–15 μm, and a salt spray corrosion resistance of ≥500 hours; Matte black Dacromet coating, with a coating thickness of 6–12 μm; or Physical vapor deposition forms TiN or CrN decorative wear-resistant films with a film hardness ≥1500HV.

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