Automobile door lock component machining process

Abstract

The application discloses a kind of automobile door lock parts processing technology, belong to precision stamping processing technical field, to solve the problem of traditional process forming lock tongue collapse, engagement difference, easy to cause ejector pin slip off, door lock function failure, driving abnormal sound and safety hazard.This application adopts hierarchical fine forming core scheme, by adding profile pre-cutting edge station and profile half-precision punching forming station cooperate processing, with small blanking gap, low-speed blanking, three-stage stamping mode of stable voltage, lock tongue collapse depth is stably controlled within 15% of material thickness.At the same time, supporting substrate pretreatment, multi-station stress release and integrated post-processing procedure, guarantee the size accuracy and structural performance of workpiece.The application effectively improves the engagement precision of lock tongue and ejector pin, eliminates the problem of ejector pin loosening and door lock failure from the root, significantly improves the forming quality, reliability and durability of the product, and is suitable for high-precision automobile door lock tongue batch production.

Description

Technical Field

[0002] This application relates to the technical field of precision stamping, and in particular to a processing technology for automotive door lock parts. Background Technology

[0004] The car door lock tongue is the core load-bearing and engaging component of the car door lock mechanism. Through precise cooperation with the door lock pin and the latch, it realizes the locking, limiting and anti-disengagement functions of the car door. Its molding precision, cross-sectional quality and dimensional stability directly determine the smoothness of the car door opening and closing, the reliability of locking and the safety of the whole vehicle.

[0005] In related technologies, the bolts of mass-produced car door locks in the industry are generally processed and formed using a traditional progressive die distribution stamping process. Due to the limitations of conventional stamping process control standards, the collapse angle of the rear face of the bolt stamping is generally controlled within a tolerance range of 30% of the material thickness. This process is a common and conventional processing method that does not require changes to the product structure or mold structure and can complete mass production by relying solely on conventional stamping parameters.

[0006] The problem with this technology is that the existing 30% corner collapse processing technology has significant functional defects and durability failure risks during actual mass production and vehicle assembly. Specifically, the large corner collapse structure of the latch cross-section leads to a significant reduction in the effective engagement contact area between the latch and the door lock pin. The latch engagement forms a sloping transition structure, which cannot achieve a flat and tight surface fit and limit with the pin. Under conditions such as vehicle bumps, repeated door opening and closing impacts, and vehicle vibration, the pin is continuously subjected to lateral force and sliding external force, which can easily lead to force deviation and limit failure, ultimately causing the door lock pin to loosen and pop out, directly resulting in a loose door lock. This leads to poor locking, abnormal noises from the vehicle door, and in severe cases, the safety hazard of the door opening unexpectedly, reducing the reliability and durability of the car door lock. Summary of the Invention

[0008] In order to accurately reduce the collapse angle of the latch and reduce the probability of the door lock pin falling off and failing, this application provides a processing technology for automotive door lock parts.

[0009] The technical solution for processing automotive door lock components provided in this application is as follows:

[0010] A processing technology for automotive door lock parts, S1. Selecting fine-stamped steel as the base material, and performing standardized pretreatment on the steel strip to make the strip thickness uniform, the base material plastic structure uniform and stable and without residual processing stress, thereby obtaining a shaped base material;

[0011] S2. The pre-treated strip is formed in steps using a continuous stamping die; along the strip feed direction, the die forming section is sequentially set with upper and lower double-sided chamfering station, precision punching station, outer pre-cutting station, and outer semi-precision stamping forming station.

[0012] During the pre-cutting and semi-finishing of the outer shape, the single-sided punching gap between the two stations is reduced, while the stamping rate is reduced and the plastic deformation time of the material is extended. This suppresses the tearing and corner collapse defects of the stamping section and controls the corner collapse depth of the workpiece to within 15% of the material thickness. After the coordinated continuous operation of each station, the semi-finished product of the locking tongue is obtained.

[0013] The pre-cutting station uses a sharp, straight cutting edge without rounded corners to perform shallow pre-cutting. The semi-finished blanking station is equipped with an elastic pressure structure and adopts a three-stage stamping mode of fast advance, low-speed blanking, and stable pressure to maintain shape, and controls the workpiece collapse corner accuracy through graded forming.

[0014] S3. Perform integrated post-processing on the semi-finished bolt stamping product, simultaneously completing deburring, substrate structure stabilization, surface anti-corrosion modification, and external adhesive reinforcement to obtain the finished bolt.

[0015] Optionally, in step S2, a pre-punching station with a guide hole is set at the foremost end of the mold forming section and the material feeding direction; a unified processing benchmark is established through the pre-punching guide hole to ensure the step pitch accuracy of continuous stamping and reduce the deviation of the workpiece forming size.

[0016] Optionally, in step S2, the mold is sequentially provided with an elastic pusher and a scrap cutting station downstream of the semi-finish stamping station.

[0017] The elastic ejector station uses a uniform ejection method to demold the semi-finished product, ensuring smooth ejection and no workpiece deformation during stamping; the waste cutting station simultaneously cuts off excess waste from the strip, facilitating waste collection.

[0018] Optionally, the mold is provided with several empty stations. Some empty stations are arranged between the guide hole pre-punching station and the upper and lower double-sided chamfering station, and the remaining empty stations are arranged between the precision punching station and the outer shape pre-cutting station, and between the outer shape pre-cutting station and the outer shape semi-precision punching station. The empty stations serve as buffer sections for the strip to release the residual stress of the strip rolling and the accumulated stress of continuous feeding.

[0019] Optionally, the standardized pretreatment in step S1 includes thickness finishing, straightening and leveling, degreasing and cleaning, and spheroidizing treatment sub-processes in sequence; the thickness finishing controls the thickness tolerance of the strip within ±0.02mm, and the overall spheroidization rate of the substrate is ≥95% after spheroidizing treatment.

[0020] Optionally, in step S2, the complete arrangement of the die stations along the material feed direction is as follows: guide hole pre-punching station, upper chamfering station, precision punching station, outer shape pre-cutting station, lower chamfering station, multiple sets of buffer empty station stations, outer shape semi-finish blanking forming station, elastic push blanking station, and scrap cutting station; the multiple sets of buffer empty station stations are distributed between the chamfering and punching process and the outer shape fine blanking forming process, and between the forming station and the blanking cutting station, for material strip buffering and stress release, to ensure the dimensional stability of continuous stamping.

[0021] Optionally, the single-sided punching gap between the pre-cut edge of the outer shape and the semi-finished blanking forming station is controlled at 0.01 to 0.03 mm, the punching speed in the low-speed punching stage is controlled at 80 to 150 mm / s, and the holding time in the stabilizing and shaping stage is not less than 0.5 s.

[0022] Optionally, the integrated post-processing step S3 includes rolling grinding, tempering heat treatment, Delta composite anti-corrosion coating surface treatment, plasma surface activation, full-circumferential coating molding, and full inspection packaging sub-process.

[0023] The hardness of the workpiece after tempering heat treatment is controlled at 420±70HV30; the Delta composite anti-corrosion coating is composed of a zinc layer and a chromate passivation layer, and the total thickness of the coating is controlled at 6~12μm.

[0024] In summary, this application includes at least one of the following beneficial technical effects:

[0025] 1. Through a dual-station graded forming process of pre-cutting and semi-finishing, the first step is to perform shallow pre-cutting at the pre-cutting station using a sharp, straight, and non-rounded cutting edge. This releases the material's punching stress in advance, leaves forming allowance, and avoids corner collapse defects caused by single punching. Then, the independent semi-finishing station performs finishing forming. Through an elastic pressure structure and a three-stage punching mode of fast-forward-low-speed punching-stable pressure and shape preservation, the single-side punching gap at both stations is reduced to 0.01-0.03mm, reducing the punching speed and extending the plastic deformation time. This allows the material to flow fully and uniformly, ultimately achieving a stable control of the latch tongue collapse depth within 15% of the material thickness. The formed latch tongue can achieve a complete surface fit with the door lock pin, with uniform meshing force and no lateral slippage, avoiding problems such as false locking, incomplete locking, and pin failure caused by large collapse angles. Detailed Implementation

[0027] The technical solution of this application will be further described in detail below with reference to the embodiments of the present invention. It should be noted that the following preferred embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. The core of the present invention lies in the use of a dual-station graded fine blanking process that combines pre-cutting of the outer edge with semi-fine blanking of the outer edge, which solves the technical problems of excessive collapse angle and insufficient meshing accuracy of traditional one-piece stamping forming of the lock tongue, which easily leads to slippage and detachment of the ejector pin and failure of the door lock function. Through the matching substrate pretreatment, multi-station continuous stamping and integrated post-processing, the forming accuracy and reliability of the automotive door lock lock tongue are significantly improved.

[0028] In the substrate pretreatment process, this invention selects precision-stamped steel coils suitable for high-precision precision stamping as the processing substrate. The continuous steel strip undergoes sequential thickness finishing, straightening and leveling, degreasing and cleaning, and spheroidizing treatments to achieve standardized control over the strip's dimensional accuracy, surface flatness, surface cleanliness, and metallographic structure. Specifically, the steel strip is first finished using precision rolling equipment to correct uneven thickness and localized dimensional deviations in the raw material, stabilizing the overall thickness tolerance of the strip within ±0.02mm. This ensures uniform thickness throughout the entire coil and eliminates dimensional errors in subsequent continuous stamping.

[0029] Subsequently, multiple sets of straightening rollers are used to continuously straighten the finished strip, correcting warping, bending, and local deformation defects that occurred during the rolling, storage, and transfer of the strip. This ensures a flat strip surface and smooth feed, effectively avoiding problems such as station misalignment and dimensional fluctuations caused by strip deformation during continuous stamping. After straightening, a combined cleaning process of solvent washing, high-pressure air shower, and drying thoroughly removes rolling oil, dust particles, and surface oxide impurities from the strip surface. This ensures a clean and foreign-free processing surface, preventing residual impurities from affecting stamping quality and damaging the mold cavity. It also avoids defects such as poor bonding in subsequent plating and coating processes.

[0030] Finally, the cleaned strip is subjected to isothermal spheroidizing heat treatment to optimize the internal metallographic structure of the steel, promote the full spheroidization and dispersion of lamellar carbides inside the steel, effectively eliminate residual stress from the rolling of the substrate, and obtain a fine blanking substrate with uniform plasticity, excellent toughness and high forming stability. It can be fully adapted to the subsequent low-speed, stable pressure and long-time plastic fine blanking forming process, avoid forming defects such as fine blanking cracking and cross-sectional tearing from the raw material end, and provide a reliable material basis for high-precision lock tongue forming.

[0031] After the substrate pretreatment is completed, the strip is fed into a continuous progressive stamping die to perform multi-station continuous graded fine stamping forming operations. The die is arranged along the strip feed direction with a pre-punching station for guide holes, a chamfering station, a precision punching station, a pre-trimming station for the outer shape, multiple buffer stations, a semi-fine stamping station for the outer shape, a flexible push-out station, and a scrap cutting station. These stations work together to complete the continuous forming of the latch. During processing, a positioning guide hole is first punched at the strip reference position through the front-end guide hole pre-punching station. This guide hole serves as a unified processing reference throughout the entire process, accurately locking the continuous stamping step distance, effectively suppressing the cumulative dimensional deviations caused by multi-stage segmented forming, and ensuring the dimensional consistency of batch products.

[0032] The strip material then sequentially passes through the upper chamfering station, the precision punching station, and the lower chamfering station to complete the precision punching of the latch mounting hole and the double-sided chamfering of the upper and lower end faces, achieving pre-forming of the latch assembly structure and ensuring the fitting accuracy of subsequent component assembly. Multiple sets of buffer stations are arranged between the functional stations. Utilizing the static buffering effect of the buffer stations, the residual rolling stress of the strip material and the accumulated stress from continuous feed tension are released in stages, avoiding warping, misalignment, and poor forming problems caused by local stress concentration in the strip material, further improving the stability of continuous stamping forming.

[0033] The strip material then enters the core forming station of this invention, where it sequentially completes the graded fine blanking operations of pre-cutting the outer edge and semi-finish blanking of the outer shape. This is a key technical means for this invention to improve the collapse corner defect of the latch and prevent the failure of the ejector pin falling off. Among them, the pre-cutting station adopts a sharp and straight cutting edge structure without rounded corners to perform shallow pre-cutting processing on the outer contour of the latch, removing excess machining allowance on the outer periphery of the workpiece in advance and pre-forming the basic contour, releasing concentrated blanking stress in advance, avoiding the defects of instantaneous material fracture, large-area collapse corner, and cross-sectional tearing that exist in the traditional single-piece blanking process, and reserving a uniform and stable plastic deformation allowance for subsequent high-precision semi-finish blanking.

[0034] After pre-cutting and forming, the strip enters the semi-finish blanking forming station. This station is equipped with a full-area elastic pressure structure, which clamps and positions the workpiece throughout the forming process, effectively preventing material slippage and warping. This station adopts a three-stage exclusive stamping forming mode of rapid approach, low-speed fine blanking, and stable pressure to maintain shape. By reducing the blanking gap, decreasing the stamping rate, and extending the plastic deformation time, it promotes full and uniform plastic flow of steel material, replacing the traditional instantaneous brittle fracture forming method. This fundamentally suppresses forming defects such as corner collapse, tearing, and burrs, and precisely controls the forming quality of the locking tongue engagement end face.

[0035] After the core forming process is completed, the semi-finished latch enters the downstream station for demolding and waste disposal. The semi-finished product is smoothly demolded using a uniform, multi-point ejection method at the elastic push-out station, eliminating workpiece deformation and warping caused by single-point ejection and ensuring the overall shape accuracy of the latch. Simultaneously, the waste cutting station continuously cuts off excess connecting waste strips, achieving automatic separation of finished product and waste, ensuring continuous and stable operation of the production line, and ultimately obtaining a high-precision, low-collapse, and deformation-free stamped semi-finished latch.

[0036] After stamping, the semi-finished latch undergoes integrated post-processing, including rolling grinding, tempering heat treatment, Delta composite anti-corrosion coating, plasma surface activation, full-circumferential rubber coating, and full-inspection packaging. This process comprehensively improves the latch's surface quality, structural strength, corrosion resistance, and assembly stability. First, precision rolling grinding equipment is used to thoroughly grind the overall contour, stamped cross-section, and hole edges of the latch, completely removing residual burrs, sharp edges, and cross-sectional debris. This ensures a smooth and regular workpiece contour, preventing subsequent assembly jamming, surface scratches, and abnormal meshing clearances.

[0037] After grinding, the latch tongue undergoes constant-temperature tempering heat treatment to optimize the internal metallographic structure of the workpiece, completely eliminate residual stress from stamping, and significantly improve the overall structural strength and wear resistance of the latch tongue. This effectively avoids deformation and loosening caused by long-term repeated meshing and wear. After heat treatment, a zinc layer and a chromate passivation layer are sequentially laminated onto the metal surface of the latch tongue to form a uniform and dense Delta composite anti-corrosion coating. The coating is free of pinholes and peeling, significantly improving the latch tongue's resistance to rust, salt spray, and moisture, making it suitable for the complex high and low temperature and alternating wet and dry service environments of vehicles.

[0038] Next, plasma surface activation modification treatment is applied to the latch tongue area to break the passivation film on the metal surface, improve the surface roughness and surface activity of the substrate, and effectively enhance the adhesion between the subsequent plastic coating layer and the metal substrate, preventing peeling and detachment of the coating layer. After activation treatment, circumferential coating is completed around the latch tongue engagement area and its outer perimeter to form a uniform buffer plastic protective layer, which can effectively buffer the impact of door opening and closing, reduce abnormal noises during driving, and further protect the metal substrate, improving product durability. Finally, the finished latch tongue's dimensions, corner accuracy, surface hardness, coating thickness, and coating adhesion strength are comprehensively tested. Qualified products are selected for dustproof storage and neat packaging, completing the finished product preparation.

[0039] The present invention provides two preferred embodiments with different parameters, which are respectively adapted to conventional mass production and high-end, demanding production conditions, and can be flexibly selected according to the product's precision and performance requirements.

[0040] As a preferred embodiment for mass production of the present invention, this embodiment is suitable for the mass production of door lock tongues in ordinary passenger vehicles. It features strong adaptability of process parameters, high production stability, and excellent mass production yield. In this embodiment, the thickness tolerance of the material strip is controlled within ±0.02mm and the spheroidization rate of the steel is controlled at 95% during the substrate pretreatment stage. During the stamping stage, the single-sided blanking gap between the pre-cutting station and the semi-finishing station is set to 0.02mm. The stamping speed in the low-speed blanking stage is selected as 120mm / s, and the stabilization and shaping time is controlled at 0.5s. After forming, the workpiece collapse depth is stably controlled within 15% of the material thickness. In the post-processing stage, the tempering hardness of the lock tongue is controlled at 420HV30, and the total thickness of the Delta composite anti-corrosion coating is selected as 8μm. This can stably produce lock tongue products with qualified dimensional accuracy, controllable collapse defects, and qualified performance, meeting the needs of mass assembly and use in conventional vehicle models.

[0041] As a preferred embodiment of the present invention for high-precision and demanding working conditions, this embodiment is suitable for the production of door lock tongues for high-end models with high durability and high reliability requirements, resulting in higher forming precision and better product durability. In this embodiment, the thickness tolerance of the strip is also controlled within ±0.02mm during the substrate pretreatment stage, the spheroidization rate of the steel is increased to 98%, and the plasticity uniformity and forming stability of the substrate are better. During the stamping stage, the single-sided blanking gap between the pre-cutting station and the semi-finishing station is reduced to 0.01mm, the stamping speed is selected at 90mm / s during the low-speed blanking stage, and the pressure stabilization and shaping time is extended to 0.8s. After forming, the workpiece collapse depth is stably controlled within the range of 12% to 15% of the material thickness, and the flatness of the meshing end face is significantly improved. In the post-treatment stage, the tempering hardness of the lock tongue is controlled at 450HV30, and the total thickness of the Delta composite anti-corrosion coating is selected at 10μm. The wear resistance, corrosion resistance, and fatigue resistance of the product are further improved, which can meet the demanding working conditions of long-term and high-frequency use in high-end models.

[0042] Both preferred embodiments employ the core graded fine blanking process of this invention, which combines pre-cutting and shallow pre-cutting with semi-fine blanking and low-speed stable pressure forming. This process can strictly control the collapse angle depth of the latch tongue to within 15% of the material thickness, significantly optimizing the forming quality compared to the 30% collapse angle limit of the traditional one-piece stamping process. The latch tongue engagement end face formed by this invention is flat and bright, forming a complete surface fit and limit with the door lock pin, completely eliminating the slippage gap caused by the traditional large collapse angle structure. This fundamentally prevents problems such as pin offset, loosening, and falling off, effectively solving safety hazards such as door lock mis-locking, abnormal noises during driving, locking failure, and accidental opening of the door.

[0043] Among them, the conventional mass production embodiment is adapted to large-scale industrial production, with high production efficiency, controllable process costs, and good consistency of batch products. The high-precision and demanding working condition embodiment further improves the proportion of bright band and dimensional accuracy of the stamped section by reducing the blanking gap, reducing the stamping speed, and extending the holding time. The product has better wear resistance, corrosion resistance, fatigue resistance, and durability, and is suitable for the high reliability requirements of high-end vehicle models. The two sets of embodiments combine refined substrate pretreatment, multi-station stress release, and integrated composite post-processing technology to produce lock tongues with significantly better overall quality than products made by traditional processes. They can fully meet the requirements of high precision, long durability, and high security for mass production assembly and long-term use of automotive door locks.

[0044] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A processing technology for automotive door lock components, characterized in that, Includes the following steps: S1. Select fine stamping steel as the base material, and perform standardized pretreatment on the steel strip to make the strip thickness uniform, the plastic structure of the base material uniform and stable, and without residual processing stress, so as to obtain the shaped base material. S2. The pre-treated strip is formed in steps using a continuous stamping die; along the strip feed direction, the die forming section is sequentially set with upper and lower double-sided chamfering station, precision punching station, outer pre-cutting station, and outer semi-precision stamping forming station. During the pre-cutting and semi-finishing of the outer shape, the single-sided punching gap between the two stations is reduced, while the stamping rate is reduced and the plastic deformation time of the material is extended. This suppresses the tearing and corner collapse defects of the stamping section and controls the corner collapse depth of the workpiece to within 15% of the material thickness. After the coordinated continuous operation of each station, the semi-finished product of the locking tongue is obtained. The pre-cutting station uses a sharp, straight cutting edge without rounded corners to perform shallow pre-cutting. The semi-finished blanking station is equipped with an elastic pressure structure and adopts a three-stage stamping mode of fast advance, low-speed blanking, and stable pressure to maintain shape, and controls the workpiece collapse corner accuracy through graded forming. S3. Perform integrated post-processing on the semi-finished bolt stamping product, simultaneously completing deburring, substrate structure stabilization, surface anti-corrosion modification, and external adhesive reinforcement to obtain the finished bolt.

2. The processing technology for automotive door lock components according to claim 1, characterized in that, In step S2, a pre-punching station with a guide hole is set at the foremost end of the mold forming section and the material feeding direction; a unified processing benchmark is established through the pre-punching guide hole to ensure the step pitch accuracy of continuous stamping and reduce the deviation of the workpiece forming size.

3. The processing technology for automotive door lock components according to claim 1, characterized in that, In step S2, the mold is sequentially set with an elastic pusher and a scrap cutting station downstream of the semi-finish stamping station. The elastic ejector station uses a uniform ejection method to demold the semi-finished product, ensuring smooth ejection and no workpiece deformation during stamping; the waste cutting station simultaneously cuts off excess waste from the strip, facilitating waste collection.

4. The processing technology for automotive door lock components according to claim 2, characterized in that, The mold is equipped with several empty stations. Some empty stations are arranged between the guide hole pre-punching station and the upper and lower double-sided chamfering station. The remaining empty stations are arranged between the precision punching station and the outer shape pre-cutting station, and between the outer shape pre-cutting station and the outer shape semi-precision punching station. The empty stations serve as buffer sections for the strip, releasing the residual stress of the strip rolling and the accumulated stress of continuous feeding.

5. The processing technology for automotive door lock components according to claim 1, characterized in that, The standardized pretreatment in step S1 includes thickness finishing, straightening and leveling, degreasing and cleaning, and spheroidizing treatment sub-processes in sequence; the thickness finishing controls the thickness tolerance of the strip within ±0.02mm, and the overall spheroidization rate of the substrate is ≥95% after spheroidizing treatment.

6. The processing technology for automotive door lock components according to claim 5, characterized in that, In step S2, the complete station arrangement of the mold along the material feed direction is as follows: guide hole pre-punching station, upper chamfering station, precision punching station, outer shape pre-cutting station, lower chamfering station, multiple sets of buffer empty station stations, outer shape semi-fine blanking forming station, elastic push blanking station and scrap cutting station; the multiple sets of buffer empty station stations are distributed between the chamfering and punching process and the outer shape fine blanking forming process, and between the forming station and the blanking cutting station, for material strip buffering and stress release, to ensure the dimensional stability of continuous stamping.

7. The processing technology for automotive door lock components according to claim 1, characterized in that, The single-sided punching gap between the pre-cut edge of the outer shape and the semi-finished blanking forming station is controlled at 0.01 to 0.03 mm. The punching speed in the low-speed punching stage is controlled at 80 to 150 mm / s. The holding time in the stabilizing and shaping stage is not less than 0.5 s.

8. The processing technology for automotive door lock components according to claim 1, characterized in that, The integrated post-processing step S3 includes rolling grinding, tempering heat treatment, Delta composite anti-corrosion coating surface treatment, plasma surface activation, full-circumferential coating molding, and full inspection and packaging processes. The hardness of the workpiece after tempering heat treatment is controlled at 420±70HV30; the Delta composite anti-corrosion coating is composed of a zinc layer and a chromate passivation layer, and the total thickness of the coating is controlled at 6~12μm.