A processing method of continuous impact forging and in-die tapping

Abstract

The application discloses a processing method for continuous punching and die-in tapping, which comprises the following steps: punching a process seam perpendicular to the feeding direction on the strip; forging and pressing the area between the two adjacent process seams on the strip to form a protruding part; punching the protruding part of the strip in a vertical punching mode; detecting whether the positioning pin hole extends into the positioning pin to determine whether the positioning of the strip is correct; if the positioning is correct, tapping the punched hole in a vertical feeding mode; continuously punching and cutting the material to form the unfolded shape of the workpiece and cut out the contour of the two sides of the U-shaped spring piece buckle nut; stamping and bending, step-by-step bending the two sides of the buckle and the U-shaped clamping structure; and separating the formed product from the strip. The method can ensure that full front detection is completed before tapping of each set of die, reduces problems such as die deflection and irregularity from the source, and avoids hidden dangers of directly entering the tapping process without detection.

Description

Technical Field

[0001] This invention relates to the field of automotive parts processing technology, and in particular to a processing method for continuous forging and in-die tapping. Background Technology

[0002] In existing technologies, snap-fit ​​nuts are a combination fastener that provides quick positioning and anti-rotation tightening. Their core value lies in solving the efficiency and reliability issues during the assembly of thin plates / profiles. To ensure reliable installation and fixing of automotive interior panels, it eliminates the need for hand-held nuts, welding / tapping, and allows for easy insertion into the square holes / grooves of the sheet metal or profiles from one side, enabling blind assembly and significantly improving assembly line efficiency. The snap-fit ​​spring automatically opens and locks, preventing it from falling off after installation, making it suitable for confined spaces and scenarios where rear-side operation is impossible. The snap-fit ​​structure prevents rotation when the bolt is tightened, avoiding nut slippage. The elastic snap-fit ​​absorbs vibration, effectively preventing thread loosening in high-frequency vibration environments such as those found in automobiles and construction machinery.

[0003] Tapping is a critical process in the production of U-shaped spring clip nut molds. Pre-tapping inspection directly determines the quality of thread processing and assembly compatibility, preventing batch scrap after tapping. Currently, problems in this stage mainly focus on three dimensions: inspection process, inspection accuracy, and inspection management, specifically as follows: 1. Incomplete or unreasonable inspection process, failing to form a closed loop; There is no clear inspection process before tapping, relying solely on operator experience. Key reference points and dimensions at the tapping station are not pre-inspected, leading directly to tapping, resulting in subsequent thread misalignment and irregular tooth profiles. 2. Disorganized inspection sequence, failing to follow the principle of "reference point inspection first, dimensions later," inspecting non-critical dimensions before tapping positioning references, causing reference deviations to go undetected, rendering subsequent dimensional inspections meaningless. 3. Lack of post-inspection anomaly handling process; after detecting mold positioning deviations and dimensional errors, production continues without timely shutdown and rectification, leading to batch tapping defects. Furthermore, the anomalies are not recorded, making it impossible to trace the root cause of the problem. II. Insufficient inspection accuracy, resulting in missed or incorrect inspections of key items; inadequate positioning benchmark inspection, failure to check the position and perpendicularity of the locating pins and slots at the tapping station of the mold, leading to misalignment between the nut hole and the thread centerline during tapping, resulting in thread tilting, stripping, and inability to properly fit the screw. Inaccurate hole diameter inspection, failure to accurately check the diameter, roundness, and burr condition of the nut mounting holes on the mold before tapping; excessively large hole diameters can lead to insufficient thread height after tapping, while excessively small hole diameters can cause tapping chipping and thread scratches; unremoved burrs will affect the smoothness of tapping. Inappropriate selection of inspection tools, failure to select inspection tools with appropriate precision according to the mold's precision requirements (such as using ordinary calipers instead of micrometers or dial indicators), leading to deviations in inspection data and inability to accurately determine whether the mold meets the tapping requirements; some inspection tools are not calibrated regularly, resulting in loss of precision and further exacerbating incorrect inspections. Key issues include: omissions in key inspection items, such as the flatness and coaxiality of the tapping station on the mold, and the relative position of the U-shaped spring and nut seat after connection. This leads to uneven force during tapping, thread deformation and breakage, or misalignment between the thread and the spring hole during assembly. Thirdly, inadequate inspection management results in inconsistent quality. Inspectors lack sufficient expertise, failing to grasp key points of pre-tapping inspection and lacking clarity on positioning benchmarks and dimensional tolerance standards, leading to misjudgments and omissions, especially regarding subtle benchmark deviations and burrs. The absence of clear inspection standards and specific parameters for pre-tapping inspection (such as locating pin position tolerance and hole diameter deviation range) results in inconsistent inspection standards among different operators, leading to significant differences in inspection results for the same batch of molds and unstable tapping quality. Incomplete inspection records, lacking detailed documentation of pre-tapping inspection data, personnel, and time for each mold, make it impossible to trace the source of tapping defects—whether it's a problem in the inspection process or the mold's manufacturing—making targeted rectification difficult. Insufficient inspection frequency during mass production, with only the first mold being inspected before tapping, and subsequent batches not being sampled or fully inspected, means that problems such as positioning wear and dimensional drift that occur during the production process cannot be detected in time, leading to the scrapping of batches of molds. Summary of the Invention

[0004] The purpose of this invention is to provide a continuous forging and in-die tapping processing method to overcome the above-mentioned defects in the prior art.

[0005] A continuous forging and in-die tapping processing method for producing U-shaped spring clip nuts includes a sheet metal continuous stamping die and a feeding device. The sheet metal continuous stamping die is divided into an upper die and a lower die. The sheet metal continuous stamping die is sequentially provided with a pre-processing station, a forging and forming station, a vertical punching station, an inspection and positioning station, a vertical tapping station, a vertical punching station, a bending and forming station, and a blanking station. The inspection and positioning station performs visual inspection of the positioning pin holes on the strip. The method also includes the following steps: Step a, feeding the strip to the pre-processing station and punching a process seam perpendicular to the feeding direction on the strip, the process seam being used to restrict the lateral flow of material during forging; Step b, at the forging and forming station, punching a process seam perpendicular to the feeding direction on the strip located at the two adjacent process seams. Step c) Forging is performed in the area between the seams to form a protrusion; Step d) At the vertical punching station, the protrusion of the strip is punched using a vertical punching method; Step d) At the detection and positioning station, it is detected whether a positioning pin is inserted into the positioning pin hole to determine whether the positioning of the strip is correct; Step e) If the positioning is correct, the punched hole is tapped using a vertical feed method at the vertical tapping station; Step f) At the vertical punching station, the material is continuously punched away to form the unfolded shape of the workpiece, and the contours of both sides of the U-shaped spring clip nut are cut out; Step g) At the bending and forming station, stamping and bending are performed, and the clips and U-shaped clamping structures on both sides are bent in steps; Step h) The formed product is separated from the strip at the blanking station.

[0006] By accurately detecting the positioning benchmark, hole diameter, and relative position, it is ensured that the nut hole and the thread centerline are concentric during tapping, thus avoiding problems such as eccentricity and uneven force.

[0007] In one embodiment, the U-shaped spring clip nut in step f has two side profiles including a base plate and symmetrically arranged limiting structures. The unfolded area of ​​the base plate is greater than the unfolded area of ​​the area where the limiting structure connects to the base plate. The limiting structure sequentially cuts out a first groove and a second groove.

[0008] In one embodiment, step g includes: step g1, sequentially bending the workpiece on the strip, bending the groove wall of the second groove near the first groove to form a first limiting part, and bending the end of the limiting structure to form a second limiting part; step g2, bending the limiting structure to form a support arm and an elastic arm, such that the connection between the support arm and the elastic arm is at a 90-degree angle; step g3, bending the elastic arm so that the first limiting part extends into the first groove; step g4, bending the support arm so that the connection between the support arm and the base plate is at a 90-degree angle; step g5, bending the support arm so that the first limiting part abuts against the nut connection hole.

[0009] In one embodiment, the vertical punching station in step c includes a vertically arranged punch and a first driving part that drives the punch to move vertically.

[0010] In one embodiment, the vertical tapping station in step e includes a vertically arranged tap and a second drive unit that drives the tap to move.

[0011] In one embodiment, step d includes image acquisition and image processing, acquiring an image containing the positioning pin hole area, the image including a target image and a background image, processing the acquired image, and identifying whether a positioning pin extends into the positioning pin hole.

[0012] In one embodiment, the image processing in step d includes: step d1, preprocessing, filtering noise from the image of the positioning pin hole region, including grayscale processing of the image of the positioning pin hole region and noise filtering operation on the grayscale processed image; step d2, image segmentation, separating the target image from the background image, selecting an appropriate threshold to divide the image of the positioning pin hole region into a target image and a background image; step d3, feature extraction, using gradient orientation histogram features to describe the features of the image of the positioning pin hole region, by dividing the image into cell units, calculating the gradient value of the cell units, grouping several cell units into blocks and normalizing the gradient within the blocks, and combining the gradient histograms of all blocks into a feature vector of the image; step d4, target recognition, performing target recognition on the image of the positioning pin hole region.

[0013] Ensure that a comprehensive pre-test is completed before tapping each mold, reducing problems such as mold skewing and irregularity from the source, and avoiding the hidden dangers of directly entering the tapping process without testing.

[0014] In one embodiment, in step e, if the positioning is detected to be incorrect, the mold is controlled to perform a repositioning operation.

[0015] In one embodiment, step h further includes visual inspection to determine whether the unloaded product is qualified. If the product is unqualified, the product is removed from the mold and guided to the waste collection area.

[0016] The above technical solution has the following advantages or beneficial effects: This continuous forging and in-die tapping processing method of the present invention ensures that a comprehensive pre-test is completed before tapping of each die set, reducing problems such as die skewing and irregularities from the source, and avoiding the hidden dangers of directly entering the tapping process without testing. Improved testing accuracy ensures thread quality and assembly compatibility, clearly defines the core testing items before tapping, and ensures that the thread processing accuracy meets requirements. It standardizes the entire process management of pre-tapping testing, improving production efficiency and product qualification rate. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the U-shaped spring clip nut according to an embodiment of the present invention.

[0018] Figure 2 This is a side view of the U-shaped spring clip nut in an embodiment of the present invention.

[0019] Figure 3 This is a schematic flowchart of a continuous forging and in-die tapping processing method according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the station structure of the sheet metal continuous stamping die on the strip in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the processing flow of the sheet metal continuous stamping die in an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the processing flow of another embodiment of the present invention.

[0023] Figure 7 This is a flowchart illustrating the bending and forming station in step g of an embodiment of the present invention.

[0024] In the diagram: 1. Base plate; 2. Limiting structure; 21. Support arm; 22. First groove; 23. First limiting part; 24. Elastic arm; 25. Second groove; 26. Second limiting part; 3. Nut sleeve; 103. Pre-treatment station; 104. Forging and forming station; 105. Vertical punching station; 106. Inspection and positioning station; 107. Vertical tapping station; 108. Vertical punching station; 109. Bending and forming station; 110. Blanking station. Detailed Implementation

[0025] The technical solutions of various embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The structural design of this device is described in detail below with reference to the accompanying drawings.

[0027] refer to Figure 3 — Figure 6A continuous forging and in-die tapping processing method for producing U-shaped spring clip nuts includes a sheet metal continuous stamping die and a feeding device. The sheet metal continuous stamping die is divided into an upper die and a lower die. The sheet metal continuous stamping die is sequentially provided with a pre-processing station 103, a forging and forming station 104, a vertical punching station 105, an inspection and positioning station 106, a vertical tapping station 107, a vertical punching and cutting station 108, a bending and forming station 109, and a blanking station 110. The inspection and positioning station 106 performs visual inspection of the positioning pin holes on the strip. The method also includes the following steps: Step a, feeding the strip into the pre-processing station 103, cutting the process seam on the strip... A narrow, long slit is punched in the material to prevent material from flowing to the sides during upsetting, thus preventing the boss from becoming eccentric and deforming to release stress, ensuring concentricity in subsequent tapping; Step b, at the forging and forming station 104, protrusions are formed in batches on the strip located between adjacent process slits. First, the boss is pre-upset (first extrusion) to locally cold-upset the threaded area, causing the material to gather upwards and initially form the boss shape. The diameter of the boss reaches 7-8.5mm. Then, the boss is precision upset (multiple extrusions) to shape it, with the diameter of the boss reaching 4.5-5.5mm and the depth reaching 5.27mm. Flatness and concentricity are then corrected; Step c, at the vertical punching station 105, The protruding part of the strip is punched using a vertical punching method. A smaller bottom hole is punched first to remove the center material, preparing for a fine hole. The fine punching reaches a standard bottom hole, resulting in a smooth, burr-free hole with high verticality. Step d: At the detection and positioning station 106, it is checked whether a positioning pin has inserted into the positioning pin hole to determine if the strip's positioning is correct. Step e: If the positioning is correct, the punched hole is tapped using a vertical feed method at the vertical tapping station 107. The in-mold tapping machine synchronously drives the extrusion tap, completing the tapping and retraction in the same stroke. Step f: At the vertical punching station 108, continuous punching removes material, forming the unfolded shape of the workpiece. The U-shaped spring clip nut has two side profiles, including a base plate and symmetrically arranged limiting structures. The unfolded area of ​​the base plate is larger than the unfolded area of ​​the area where the limiting structure connects to the base plate. The limiting structure is cut with a first groove 22 and a second groove 25 in sequence. Step g: At the bending forming station 109, the stamping and bending are performed perpendicular to the material travel direction along the center line of the protrusion. The two side clips and U-shaped clamping structures are bent in steps. The two side clips are bent in steps, with springback compensation reserved to ensure consistent clamping force. The U-shaped clamping structure is bent to ensure control of opening size and parallelism. Step h: The formed product is separated from the material at the blanking station 110.

[0028] The sheet metal progressive stamping die is a multi-station progressive die set mounted on a high-speed stamping press. The die set adopts a four-guide-pillar rolling guide structure to ensure the accuracy of the upper and lower die closing. Each station is arranged in a straight line within the same die set along the strip feeding direction. The die uses a central guide plate and side guides to guide the strip, and an automatic feeder driven by the stamping press realizes intermittent step-by-step conveying of the strip. The stamping action of each station is powered by the stamping press slide through the upper die holder, and transmitted to the workpiece through the independent punch assembly of each station. The tapping stroke is synchronized with the stamping cycle.

[0029] In another embodiment of the present invention, in step f, at the vertical punching station 108, the material is continuously punched out to form the unfolded shape of the product, and the contours of both sides of the U-shaped spring clip nut are cut out. The first groove 22 and the first limiting part 23 are punched out in sequence according to the cutting order; then the outer contour of the limiting structure 2, the second groove 25 and the second limiting part 26 are punched out, and the burrs are controlled to be ≤0.05mm.

[0030] refer to Figure 1 — Figure 2 The U-shaped spring clip nut includes a base plate 1, a nut sleeve 3, and a limiting structure 2. The base plate 1 has an opening, and the nut sleeve 3 is disposed on the base plate 1 and extends out from the surface of the base plate 1. The nut sleeve 3 has a through hole, which communicates with the opening on the base plate 1 to form a nut connection hole. At least a portion of the inner wall of the nut connection hole is threaded, and the screw and the nut connection hole are fixed to the U-shaped spring clip nut by the threaded connection. The limiting structure 2 is connected to the base plate 1 and is symmetrically arranged along the axial direction of the nut sleeve 3. The top of the limiting structure 2 is close to the axial direction of the nut sleeve 3. The limiting structure 2 includes a support arm 21 and an elastic arm 24 connected to the support arm 21. One end of the support arm 21 is connected to the base plate 1 and a first groove 22 is formed away from the connection point. The elastic arm 24 is provided with a first limiting part 23, which extends into the first groove 22 and abuts against the screw that passes through the nut connection hole.

[0031] When the screw is inserted into the automotive parts, the limiting structure is also inserted and acts as a filling and limiting mechanism, thereby increasing the connection stability between the screw and the automotive parts and effectively reducing loosening.

[0032] Preferably, the elastic arm 24 has a second groove 25, the bottom edge of which is bent at approximately 90 degrees toward the first groove 22, forming an inwardly protruding hook-shaped structure as a first limiting part 23. The end of the first limiting part 23 is an arc surface. When the screw penetrates the nut connection hole, the arc surface of the first limiting part 23, under the elastic action of the elastic arm 24, tightly adheres to the root of the external thread or the smooth part of the screw, generating a radial clamping force.

[0033] The first limiting part 23 extends into the first groove 22 and abuts against the screw. After the screw and nut are threaded together, one end is fixed with the U-shaped spring clip. The second groove 25 and the first limiting part 23 form an inwardly opening snap-fit ​​limiting. When the U-shaped spring clip nut extends into the automotive part, the screw is fixed to one end of the U-shaped spring clip nut through the nut connection hole of the nut sleeve 3. The other end of the U-shaped spring clip nut extends into the automotive part, and is fixedly connected to the automotive part by an interference fit through the second groove 25.

[0034] This design ensures that the opening distance between the two support arms 21 is smaller than the diameter of the base plate 1, and the width of the U-shaped spring opening is smaller than the width of the base plate 1, allowing the U-shaped spring clip nut to be easily inserted into the square hole / groove of the plate material. Furthermore, the height of the first groove 22 is not lower than the height of the nut sleeve 3, thereby increasing the connection stability between the insertion connecting assembly and the automotive parts, effectively reducing loosening.

[0035] Preferably, the other end of the support arm 21 is connected to one end of the elastic arm 24, and the other end of the support arm 21 is bent inward toward the first groove 22 to form the second limiting part 26. The second limiting part 26 and the first limiting part 23 form a stable support structure in the first groove 22 to prevent the elastic arm 24 from deforming and sticking to the support arm 21.

[0036] Preferably, the base plate 1 is square and its side length is greater than the length of the connection. The edge of the base plate 1 protrudes from the connection between the support arm 21 and the base plate 1, so that the U-shaped spring clip nut is fixedly connected to the automotive parts with an interference fit.

[0037] The U-shaped spring-loaded snap-fit ​​nut features an axial four-way locking structure that engages with the screw, enhancing fixing strength and reliability. The U-shaped spring-loaded snap-fit ​​nut eliminates the need for manual support, welding, or tapping; it can be easily inserted into the square hole / groove of the sheet metal from one side, enabling blind installation and significantly improving assembly line efficiency. When the nut sleeve is connected to the screw, the limiting structure 2 restricts the relative radial movement of the nut and screw. The spring clip of the limiting structure 2 automatically springs open and locks, preventing it from falling off after installation, making it suitable for confined spaces and scenarios where operation from the back is inaccessible. The snap-fit ​​nut does not rotate when the bolt is tightened, preventing slippage. When the screw is inserted into an automotive component, the limiting structure 2 also inserts and acts as a filler and limiter, increasing the connection stability between the screw and the automotive component, thus effectively reducing loosening.

[0038] refer to Figure 7Preferably, step g includes: step g1, sequentially bending the workpiece on the strip, bending the groove wall of the second groove 25 near the first groove 22 to form a first limiting part 23, and bending the end of the limiting structure to form a second limiting part 26; step g2, bending the limiting structure to form a support arm 21 and an elastic arm 24, so that the connection between the support arm 21 and the elastic arm 24 is at a 90-degree angle; step g3, bending the elastic arm 24 so that the first limiting part 23 extends into the first groove 22; step g4, bending the support arm 21 so that the connection between the support arm 21 and the base plate 1 is at a 90-degree angle; step g5, bending the support arm 21 so that the arc surface of the first limiting part 23 faces the axial direction of the nut connection hole, forming a clamping limiting structure adapted to the external thread of the screw.

[0039] Furthermore, in a preferred embodiment of the continuous forging and in-die tapping processing method of the present invention, step d includes image acquisition and image processing. An image containing the locating pin hole area is acquired, the image including a target image and a background image. The acquired image is processed to identify whether a locating pin extends into the locating pin hole. This ensures that a comprehensive pre-test is completed before tapping each set of dies, reducing problems such as die misalignment and irregularities from the source, and avoiding the potential risks of directly entering the tapping process without testing.

[0040] The detection and positioning station 106 includes a vision inspection system, which consists of an industrial camera, a ring light source, an image processing unit, and a mounting bracket. The industrial camera is fixed 500mm above the mold via the mounting bracket, with its lens optical axis perpendicular to the material plane, used to acquire images including the positioning pin holes. The ring light source is coaxially mounted around the camera lens to provide uniform illumination for image acquisition. The image processing unit is an industrial computer integrated within the mold control cabinet, connected to the industrial camera via a gigabit network cable, receiving image data and running an image processing program. The program executes the following steps: when the material moves to the detection station and is initially positioned by the mold positioning pins, the PLC sends a trigger signal to the industrial computer, which controls the industrial camera to acquire the image; subsequently, the image is grayscaled and denoised using median filtering; the Otsu method is used to automatically calculate the threshold for image segmentation, extracting the positioning pin hole area; the HOG feature vector of this area is calculated; the feature vector is input into a pre-trained SVM classifier for judgment, outputting a result of "positioning correct" or "positioning incorrect," and the result is fed back to the mold PLC control system.

[0041] Further, in a preferred embodiment of the continuous forging and in-die tapping processing method of the present invention, the image processing in step d includes: step d1, preprocessing, using median filtering to filter out noise in the image of the positioning pin hole area, including performing grayscale processing on the image of the positioning pin hole area, and performing noise filtering on the grayscale processed image. Grayscale processing is to convert a color image into a grayscale image, unifying the RGB values ​​of each pixel into a single value. The median filtering method eliminates isolated noise points by setting the median value within the neighborhood as the pixel value of the entire neighborhood. The preprocessing includes performing median filtering on the image of the positioning pin hole area. The image is converted to grayscale, and noise is filtered out. The median filtering method eliminates isolated noise points by setting the median value of the neighborhood as the pixel value of the entire neighborhood. The steps are as follows: a window of size N×N is created and moved sequentially across the image in a row-first, column-second order. After each move, the pixel values ​​within the window are reordered, and the new center position is the reordered median value. The sliding window is cyclically repeated to complete the processing of all image data. Step d2: Image segmentation. The target image is separated from the background image using a threshold segmentation method. The preprocessed image is then processed... To segment the image of the positioning pin hole area into a target image and a background image by selecting an appropriate threshold, the threshold segmentation method selects an appropriate threshold for the preprocessed image and segments the image of the positioning pin hole area into a target image and a background image. The steps are as follows: S1, Define the precision ΔT; S2, Define the initial threshold T0, which can be the grayscale mean; S3, Based on the current threshold T, group the grayscale values ​​greater than T into one group and take their average value as m1; group the grayscale values ​​less than T into another group and take their average value as m2; S4, Obtain the new threshold T = (m1 + m2) / 2; S5, Repeat steps S3 and S4 until the difference between the previous and subsequent thresholds is less than ΔT. The threshold T is a suitable threshold; Step d3, feature extraction, using gradient direction histogram features to describe the features of the image of the positioning pin hole region, by dividing the image into cell units, calculating the gradient value of the cell units, forming several cell units into blocks and normalizing the gradient within the blocks, and combining the gradient histograms of all blocks into the feature vector of the image; Step d4, target recognition, performing target recognition on the image of the positioning pin hole region.

[0042] Specifically, the input image's preset region of interest (ROI) is converted to grayscale, transforming a multi-channel color image into a single-channel grayscale image. This process removes redundant color information, simplifies subsequent feature calculations, and lays the foundation for later processing. To eliminate interference from isolated noise points in the image, median filtering is used to denoise the grayscale image. By setting a 3×3 or 5×5 neighborhood window, the median grayscale value of all pixels within the window is selected as the new value for the center pixel. This effectively suppresses noise while preserving target edge details to the greatest extent, avoiding feature loss due to edge blurring. Subsequently, thresholding is used to segment the denoised grayscale image. Combining the image's grayscale distribution characteristics, the optimal segmentation threshold is determined using the Otsu automatic thresholding method. Binarization clearly divides the image into target and background regions, achieving effective separation of the target and background, eliminating irrelevant background interference, and providing a clean target region for subsequent feature extraction, avoiding interference from background information. In the feature extraction stage, the Histogram of Oriented Gradients (HOG) is used to extract the core features of the target. First, the gradient magnitude and gradient direction in the horizontal and vertical directions of the image are calculated by the difference operator to capture the change information of the target edge. Then, the image is divided into 8×8 pixel cell units, and the gradient direction from 0° to 180° is divided into 9 intervals. The sum of the magnitudes of different gradient directions in each cell unit is counted to form a histogram of orientation gradients, which quantifies the local shape features of the target. 2×2 adjacent cell units are combined into a block region, and the feature vectors in the block are subjected to L2 normalization to eliminate feature distortion caused by changes in illumination and contrast. Finally, the normalized features of all blocks are stitched together to form a HOG high-dimensional feature vector that can accurately describe the edge and shape information of the target. This algorithm employs a Support Vector Machine (SVM) as the classifier, using the extracted HOG feature vectors as input. The SVM model is trained with labeled positive and negative samples (positive samples contain image features of the target, while negative samples contain background and interference image features). An RBF Gaussian kernel function is selected to map low-dimensional features to a high-dimensional space. An optimization problem is solved to find the optimal classification hyperplane in the high-dimensional feature space, achieving maximum margin classification between target and non-target samples, thus improving the model's generalization ability and reducing the risk of overfitting. After the image to be recognized undergoes the above steps of grayscale conversion, denoising, segmentation, and HOG feature extraction, its HOG feature vector is input into the trained SVM model. The classification decision function outputs the recognition result, ultimately completing the target recognition task. This algorithm has a clear flow and strong operability. Through parameter optimization and synergistic cooperation in each stage, it effectively improves the accuracy and robustness of target recognition, making it suitable for various simple target detection and recognition scenarios.

[0043] Improved inspection accuracy ensures thread quality and assembly compatibility. Key pre-tapping inspection items are clearly defined, comprehensively covering the positional accuracy and perpendicularity of locating pins and slots, the diameter, roundness, and burrs of the nut mounting hole, as well as the flatness and coaxiality of the tapping station, and the relative position of the U-shaped spring and nut seat. This effectively avoids problems such as thread tilting, stripping, insufficient thread height, chipping, scoring, deformation, and breakage, ensuring that thread machining accuracy meets requirements. Precise control of core benchmarks enhances assembly compatibility: By accurately inspecting the positioning benchmarks, hole diameter, and relative position, it ensures that the nut hole and thread centerline are concentric during tapping, avoiding problems such as eccentricity and uneven force. This not only improves thread machining quality but also ensures the compatibility of subsequent nuts and screws, and the assembly coordination of the U-shaped spring and nut seat, reducing assembly jamming and failure.

[0044] Furthermore, in a preferred embodiment of the continuous forging and in-die tapping processing method of the present invention, if incorrect positioning is detected in step e, the die is controlled to perform a repositioning operation. The upper and lower dies are separated, the strip is re-fixed, and step d is repeated.

[0045] This invention precisely controls the core benchmarks and improves assembly compatibility: by accurately detecting and positioning benchmarks, hole diameters and relative positions, it ensures that the nut hole and the thread centerline are concentric during tapping, avoiding problems such as eccentricity and uneven force. This not only improves the quality of thread processing, but also ensures the compatibility of subsequent nuts and screws, and the assembly coordination of U-shaped springs and nut seats, reducing problems such as assembly jamming and assembly failure.

[0046] Furthermore, in a preferred embodiment of the continuous forging and in-die tapping processing method of the present invention, step h further includes visual inspection to determine whether the blanked product is qualified. If the product is unqualified, it is removed from the mold and placed in the scrap area. The blanking station 110 integrates a product visual inspection and sorting mechanism. This mechanism includes a side-mounted industrial camera and a backlight, used to capture the contour image of the product during its free fall after blanking. The image processing unit calculates the key dimensions of the product and compares them with a preset tolerance range, while detecting whether there are defects such as burrs exceeding tolerance or bending deformation. If it is determined to be a non-qualified product, the control system triggers a high-pressure pneumatic nozzle located on one side of the blanking path to blow the non-qualified product into the scrap collection box; qualified products fall into the finished product collection container along the guide slide.

[0047] In summary, this continuous forging and in-die tapping processing method of the present invention ensures comprehensive pre-testing of each die before tapping, reducing problems such as die misalignment and irregularities from the source, and avoiding the hidden dangers of directly entering the tapping process without testing. Clear testing standards ensure consistency in batch testing, preventing excessive differences in test results within the same batch of dies, ensuring stable tapping quality, and improving the consistency of mass production. Through the above improvements, not only is the processing quality of the tapping process guaranteed from the source, reducing batch scrap after tapping, lowering production and rework costs, but the entire process management of pre-tapping testing is also standardized, improving production efficiency and product qualification rate. This further enhances the product quality and market competitiveness of U-shaped spring clip nuts.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

[0049] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects. The scope of the invention is defined by the appended claims, not by the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A continuous forging and in-die tapping processing method for producing U-shaped spring clip nuts, comprising a sheet metal continuous stamping die and a feeding device, wherein the sheet metal continuous stamping die is divided into an upper die and a lower die, characterized in that, The sheet metal continuous stamping die is sequentially provided with a pre-processing station (103), a forging and forming station (104), a vertical punching station (105), an inspection and positioning station (106), a vertical tapping station (107), a vertical punching and cutting station (108), a bending and forming station (109), and a blanking station (110); the inspection and positioning station (106) performs visual inspection of the positioning pin holes on the strip. It also includes the following steps: Step a, feed the material into the pretreatment station (103) and punch out the process seam on the strip; Step b, at the forging and forming station (104), the area on the strip located between two adjacent process seams is forged to form a protrusion; Step c, at the vertical punching station (105), the protrusion of the strip is punched in a vertical punching manner; Step d: At the detection and positioning station (106), it is detected whether a positioning pin extends into the positioning pin hole to determine whether the positioning of the strip is correct. Step e: If the detection and positioning are correct, then in the vertical tapping station (107), the punch is tapped in a vertical feed manner; Step f: At the vertical punching station (108), the material is continuously punched away to form the unfolded shape of the workpiece and cut out the contours of both sides of the U-shaped spring clip nut. Step g: At the bending and forming station (109), stamping and bending are performed, and the buckles and U-shaped clamping structures on both sides are bent in steps. In step h, the formed product is separated from the conveyor belt at the unloading station (110); Step d includes image acquisition and image processing. An image containing the positioning pin hole area is acquired. The image includes a target image and a background image. The acquired image is processed to identify whether a positioning pin is inserted into the positioning pin hole. The image processing in step d includes: Step d1, preprocessing, filtering out noise from the image containing the positioning pin hole area, including grayscale processing of the image of the positioning pin hole area and noise filtering operation on the grayscale processed image; Step d2, image segmentation, separating the target image from the background image, selecting an appropriate threshold for the preprocessed image to divide the image containing the positioning pin hole area into the target image and the background image; Step d3, feature extraction: Gradient direction histogram features are used to describe the features of the positioning pin hole area image. The image is divided into cell units, the gradient value of the cell unit is calculated, several cell units are combined into blocks and the gradient within the block is normalized, and the gradient histograms of all blocks are combined into the feature vector of the image. Step d4, target recognition: perform target recognition on the image of the positioning pin hole area.

2. The continuous forging and in-die tapping processing method as described in claim 1, characterized in that, In step f, the U-shaped spring clip nut has two side profiles including a base plate and symmetrically arranged limiting structures. The unfolded area of ​​the base plate is greater than the unfolded area of ​​the area where the limiting structure connects with the base plate. The limiting structure sequentially cuts out the first groove (22) and the second groove (25).

3. The continuous forging and in-die tapping processing method as described in claim 2, characterized in that, Step g includes: Step g1: The workpieces on the strip are bent in sequence. The wall of the second groove (25) near the first groove (22) is bent to form a first limiting part (23). The end of the limiting structure is bent to form a second limiting part (26). Step g2, the bending limiting structure forms a support arm (21) and an elastic arm (24), so that the connection between the support arm (21) and the elastic arm (24) is at a 90-degree angle; Step g3, bend the elastic arm (24) so ​​that the first limiting part (23) extends into the first groove (22); Step g4, bend the support arm (21) so that the connection between the support arm (21) and the base plate (1) is at a 90-degree angle; Step g5, bend the support arm (21) so that the arc surface of the first limiting part (23) faces the axial direction of the nut connection hole, forming a clamping and limiting structure that is compatible with the external thread of the screw.

4. The continuous forging and in-die tapping processing method as described in claim 1, characterized in that, In step c, the protruding part of the strip is punched in a vertical punching manner using a vertically set punch and a first driving part that drives the punch to move vertically.

5. The continuous forging and in-die tapping processing method as described in claim 1, characterized in that, In step e, the punch is tapped using a vertically positioned tap and a second drive unit that drives the tap to move, in a vertical feed manner.

6. The continuous forging and in-die tapping processing method as described in claim 1, characterized in that, In step e, if the positioning is detected to be incorrect, the mold is controlled to perform a repositioning operation.

7. The continuous forging and in-die tapping processing method as described in claim 1, characterized in that, Step h also includes visual inspection to determine whether the unloaded product is qualified. If the product is not qualified, the product is removed from the mold and guided to the waste collection area.

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