A modular assembly and dimension detection device for door frames

Abstract

The application discloses a door frame modular assembly and size detection device, and belongs to the technical field of automobile part manufacturing and detection. The device comprises a modular assembly fixture, a full-automatic detection system and a reference calibration mechanism. The modular assembly fixture is composed of a universal base and four groups of replaceable positioning modules, is adapted to four kinds of door frame models respectively, and realizes rapid disassembly and docking through a standardized quick-change interface. The full-automatic detection system comprises a 3D vision camera and a laser displacement sensor. The 3D vision camera scans the overall contour of the door frame, and the laser displacement sensor collects size data such as section, hole position and straightness. A data processing unit automatically determines and generates an electronic detection report. The reference calibration mechanism is internally provided with a calibration block consistent with the body reference, and can automatically complete double-end synchronous calibration of the fixture positioning reference and the detection system detection reference after model change.

Description

Technical Field

[0001] This invention relates to the field of automotive parts manufacturing and testing technology, specifically to a modular assembly and dimensional inspection device for door frames. Background Technology

[0002] The car door frame is an important component of the car body, and it comes in four models: front left, front right, rear left, and rear right. During assembly, the door frame needs to achieve a high-precision match with the door and body pillars, with extremely stringent dimensional tolerance standards: cross-sectional dimension tolerance is required to be ±0.2mm, and mounting hole position tolerance is required to be ±0.1mm. These stringent dimensional requirements determine the crucial role of the door frame assembly and inspection process in the entire automotive manufacturing process.

[0003] Currently, the tooling and equipment used for door frame assembly and dimensional inspection in the industry generally suffer from several intractable technical defects, as follows: The tooling is highly specialized, resulting in high changeover costs and long processing times. Existing assembly fixtures are single-model-specific, with four different door frames corresponding to four completely independent fixture systems. Each fixture requires separate design, manufacturing, and debugging, leading to high tooling procurement costs. Storage of these four independent fixtures requires significant space, resulting in high storage costs. More seriously, when a product needs to be changed for production, operators must disassemble and remove the entire tooling from the production line, install another set of tooling, and readjust the positioning accuracy. This entire disassembly, assembly, and debugging process takes over 1.5 hours, resulting in extremely low production line changeover efficiency and severely hindering the automotive manufacturing company's need for flexible, multi-variety, small-batch production.

[0004] Manual inspection is inefficient and prone to large measurement errors. Currently, critical dimensions such as door frame cross-sectional dimensions, mounting hole positions, and profile straightness are all measured manually using traditional measuring tools like calipers and micrometers. A complete inspection of a single product takes at least 15 minutes, resulting in extremely low efficiency and failing to meet the requirements of mass production. Furthermore, manual reading and recording are susceptible to visual errors and other human mistakes, leading to low reliability of measurement data and hindering stable quality control under mass production conditions. With continuously increasing automobile production, manual inspection has become a bottleneck restricting both production efficiency and product quality improvement.

[0005] The assembly datum and inspection datum are not consistent, resulting in excessive clearances in the finished product assembly. The positioning datum of the traditional assembly fixture is independent of the vehicle body assembly datum, with an inherent deviation greater than 0.3mm between the two sets of datums. This deviation stems from the fact that the design datum of the assembly fixture is derived from the individual door frame drawings, while the vehicle body assembly datum is derived from the vehicle coordinate system. There is a lack of a unified datum transfer chain between the two in the design and manufacturing stages. Due to this datum deviation, door frames assembled and inspected using traditional tooling may have clearances exceeding process requirements after actual vehicle assembly, leading to batches of defective products and extremely high rework and repair costs.

[0006] The lack of electronic storage of testing data makes quality traceability difficult. Current testing methods primarily rely on paper records, resulting in scattered and fragmented data that cannot be systematically stored and managed. When quality issues arise, it is difficult to trace the original testing data for specific batches or processes, hindering process optimization and leaving quality control reliant on experience.

[0007] In summary, existing tooling equipment cannot simultaneously meet the production needs of rapid changeover for multiple models, high-precision automated testing, standardized assembly, and data-driven quality control. There is an urgent need to design an integrated, modular, and fully automated door frame assembly and testing device to address these pain points. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a modular assembly and dimension detection device for door frames, including a modular assembly fixture. The modular assembly fixture consists of a universal base and four sets of quick-change positioning modules. The four sets of positioning modules are respectively adapted to four workpiece models: front left door frame, front right door frame, rear left door frame, and rear right door frame. The positioning modules achieve quick disassembly and assembly docking with the universal base through a standardized quick-change interface. The fully automated inspection system includes a 3D vision camera, a laser displacement sensor, and a data processing unit. The 3D vision camera is used to scan the overall outline of the door frame, and the laser displacement sensor is used to collect data on the cross-sectional dimensions of the door frame, the dimensions of the mounting holes, and the straightness of the profiles. The data processing unit receives the data collected by the 3D vision camera and the laser displacement sensor, automatically determines whether the dimensions meet the tolerance standards, and automatically generates an electronic inspection report. A reference calibration mechanism is provided, which has a built-in calibration block. The shape and position dimensions of the calibration block are consistent with the assembly reference of the vehicle body. The reference calibration mechanism is used to automatically complete the dual-end synchronous calibration of the positioning reference of the modular assembly fixture and the detection reference of the fully automatic detection system after the positioning module is replaced.

[0009] Preferably, the upper surface of the universal base is provided with the standardized quick-change interface, which includes a precision positioning hole and a locking groove; the bottom of the positioning module is provided with a positioning boss that matches the precision positioning hole and a locking hook that matches the locking groove; when the positioning boss is inserted into the precision positioning hole and the locking hook is engaged with the locking groove, the positioning module is fixedly connected to the universal base.

[0010] Preferably, each positioning module includes an adjustable positioning pin and an elastic clamping mechanism; the adjustable positioning pin is disposed on the upper surface of the positioning module, and its position can be adjusted along a preset slide groove; the adjustable positioning pin has two replaceable diameter specifications of φ8mm and φ10mm; the elastic clamping mechanism includes a clamping arm and an elastic element; one end of the clamping arm is hinged to the positioning module, and the other end is provided with a clamping head; the elastic element provides continuous pressure to the clamping arm; the positioning pin and the elastic clamping mechanism together constrain the spatial position of the door frame.

[0011] Preferably, the 3D vision camera is installed directly above the modular assembly fixture to perform a one-time complete scan of the overall outline of the door frame; the laser displacement sensor has a detection accuracy of ±0.01mm, is installed on a three-dimensional motion platform, and can move along the X-axis, Y-axis, and Z-axis to perform point-by-point high-precision measurement of the door frame cross-sectional outline, mounting hole positions, and long side of the profile.

[0012] Preferably, the data processing unit has a built-in dimensional analysis program, which includes a cross-sectional dimensional analysis module, a hole position dimensional analysis module, and a straightness analysis module. The cross-sectional dimensional analysis module is used to compare the door frame outline obtained by the 3D vision camera with a standard outline and calculate the cross-sectional dimensional deviation. The hole position dimensional analysis module is used to process the hole position data collected by the laser displacement sensor and calculate the diameter and position of the mounting holes. The straightness analysis module is used to process the data collected by the laser displacement sensor along the long side of the door frame and calculate the straightness error of the profile. The data processing unit automatically compares each dimension with a preset tolerance standard and generates an electronic inspection report.

[0013] Preferably, the machining accuracy of the calibration block is ±0.005mm, and the shape and position dimensions of the calibration block are completely consistent with the assembly datum of the A158 vehicle body. The datum calibration mechanism also includes a calibration block drive device and a calibration control system. The calibration block drive device is used to drive the calibration block to switch between a standby position and a working position. The calibration control system is used to control the automatic calibration process of the calibration block and correct the origin of the detection coordinate system of the fully automatic detection system according to the calibration results.

[0014] Preferably, when the reference calibration mechanism performs automatic calibration, the calibration block driving device drives the calibration block from the standby position to the working position, the fully automatic detection system scans and measures the calibration block, the data processing unit compares the measured data with the standard data of the calibration block and calculates the deviation value, and the calibration control system automatically corrects the origin of the detection coordinate system of the fully automatic detection system according to the deviation value, thereby completing the synchronous calibration of the positioning reference of the modular assembly fixture and the detection reference of the fully automatic detection system.

[0015] Preferably, the positioning module can be quickly disassembled and connected to the universal base through the standardized quick-change interface, and the overall product changeover time is controlled within 20 minutes; the door frame assembled by the modular assembly fixture has a basic assembly gap controlled within 0.2mm.

[0016] Preferably, the fully automatic inspection system takes no more than 3 minutes to inspect the complete dimensions of a single door frame; the laser displacement sensor has a detection accuracy of ±0.01mm; the data processing unit automatically completes data acquisition, calculation, and judgment without human intervention; the electronic inspection report includes the workpiece number, model information, production time, measured value of each dimension, deviation value, judgment result, and comprehensive judgment conclusion.

[0017] Preferably, the data processing unit further includes a database storage module, which stores the complete electronic inspection report and original collected data for each door frame; the database storage module supports data retrieval and export by workpiece number, production time period, and out-of-tolerance type for quality traceability and process optimization analysis.

[0018] The technical effects and advantages of this invention are as follows: 1. This invention adopts a modular architecture of "one universal base and four quick-change positioning modules," replacing the traditional four sets of independent dedicated fixtures. The overall number of tooling fixtures is reduced by 75%, significantly reducing storage space, tooling procurement costs, and maintenance and storage costs. Product changeover time is shortened from more than 1.5 hours to less than 20 minutes, and the efficiency of multi-model switching on the production line is improved by more than 4 times, effectively meeting the needs of automobile manufacturers for flexible production of multiple varieties and small batches.

[0019] 2. This invention eliminates the traditional manual measurement method using measuring tools, reducing the time for inspecting the complete dimensions of a single door frame from 15 minutes or more to less than 3 minutes, increasing inspection efficiency by more than 5 times. The laser displacement sensor achieves a detection accuracy of ±0.01mm, with the entire process automated, including data acquisition and calculation, completely eliminating errors from manual readings and recording, resulting in 100% accuracy. Simultaneously, automated inspection significantly reduces the manpower required for manual inspection, freeing up the labor force of inspection personnel.

[0020] 3. This invention achieves automatic synchronous calibration of the assembly fixture positioning reference and the detection system's detection reference by setting a high-precision calibration block that perfectly matches the vehicle body assembly reference. This completely solves the industry problem of inherent deviations greater than 0.3mm between the fixture positioning reference and the vehicle body assembly reference in traditional tooling. After assembly and testing by this device, the door frame's fitting clearance is stably controlled within 0.6mm, significantly reducing defective products caused by excessive assembly clearance and substantially lowering rework and repair costs.

[0021] 4. The fully automated inspection system of this invention automatically retains a complete electronic inspection report for each door frame, storing information including all original dimensional data, judgment results, production time, workpiece model, etc. The system supports the retrieval, export, and analysis of historical data, facilitating production anomaly tracing, process optimization and adjustment, and factory quality verification, fully adapting to the digital quality control needs of modern factories. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the modular assembly and dimension detection device for the door frame of the present invention; Figure 2 This describes the disassembly relationship between the base and the replaceable positioning module in the modular assembly and dimension detection device for door frames provided in this application embodiment; Figure 3 This is a schematic diagram of the reference calibration mechanism; Figure 4 This is a layout diagram of a fully automated detection system.

[0023] In the diagram: 100, Modular assembly fixture; 110, Universal base; 111, Standardized quick-change interface; 120, Positioning module; 121, Module base plate; 122, Adjustable positioning pin; 123, Elastic clamping mechanism; 200, Fully automatic detection system; 210, 3D vision camera; 220, Laser displacement sensor; 230, Data processing unit; 300, Reference calibration mechanism; 310, Calibration block; 320, Calibration block drive device; 330, Calibration control system. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose. Example 1 Please see Figures 1-4 This embodiment provides a modular assembly and dimension detection device for door frames, which includes three core components: a modular assembly fixture 100, a fully automatic detection system 200, and a benchmark calibration mechanism 300.

[0025] The modular assembly fixture 100 is located at the bottom of the device, serving as the basic support for the entire device and the execution mechanism for door frame positioning and assembly. The fully automatic detection system 200 is located above and to the side of the modular assembly fixture 100, fixed by a bracket, and its detection elements are aligned with the door frame workpiece placed on the modular assembly fixture 100. The reference calibration mechanism 300 is located on one side of the modular assembly fixture 100, maintaining signal connection and mechanical association with both the modular assembly fixture 100 and the fully automatic detection system 200.

[0026] The modular assembly fixture 100 further includes a universal base 110 and four sets of quick-change positioning modules 120. The universal base 110 is a flat plate structure, cast from high-strength cast iron, providing excellent rigidity and stability. The upper surface of the universal base 110 is provided with standardized quick-change interfaces 111, which are arrayed positioning holes and locking grooves. The bottom of the universal base 110 is provided with anchor bolt mounting holes for securing the entire assembly to the production workshop floor.

[0027] The four positioning modules 120 correspond to four workpiece models: front left door frame, front right door frame, rear left door frame, and rear right door frame. Each positioning module 120 includes a module base plate 121, an adjustable positioning pin 122, and an elastic clamping mechanism 123. The bottom surface of the module base plate 121 is provided with a mating boss and a locking hook that match the quick-change interface 111 of the universal base 110. When the positioning module 120 is installed on the universal base 110, the mating boss is inserted into the positioning hole of the quick-change interface 111, and the locking hook engages with the locking groove of the quick-change interface 111, achieving a quick and accurate mechanical connection.

[0028] An adjustable positioning pin 122 is disposed on the upper surface of the module base plate 121, and its position can be adjusted according to the reference hole position of the corresponding door frame model. The positioning pin 122 has two replaceable pin body diameter specifications of φ8mm and φ10mm, and the operator can select the appropriate pin body for installation according to the hole diameter of the reference hole of the door frame. The elastic clamping mechanism 123 includes a clamping arm and an elastic element. One end of the clamping arm is hinged to the module base plate 121, and the other end is provided with a clamping head; the elastic element is a compression spring or a gas spring, and its two ends are respectively connected to the module base plate 121 and the clamping arm, providing continuous pressure to the clamping arm.

[0029] The fully automated inspection system 200 includes a 20-megapixel 3D vision camera 210, a laser displacement sensor 220, and a data processing unit 230. The 3D vision camera 210 is an industrial-grade area scan camera with a resolution of 20 megapixels. It is mounted directly above the modular assembly fixture 100, with its lens pointing vertically downwards at the door frame workpiece. The field of view of the 3D vision camera 210 covers the entire outline of the door frame, enabling a complete scan of the entire door frame outline in a single operation.

[0030] The laser displacement sensor 220 is a high-precision point laser displacement sensor with a measurement accuracy of ±0.01mm. The laser displacement sensor 220 is mounted on a three-dimensional motion platform, which can move the laser displacement sensor 220 along the X, Y, and Z axes. During the detection process, the laser displacement sensor 220 collects high-precision dimensional data point by point along the cross-sectional contour line of the door frame, the center of the mounting holes, and the long side of the profile.

[0031] The data processing unit 230 is an industrial control computer that connects to the 3D vision camera 210 and the laser displacement sensor 220 via a data cable, receiving all raw data collected by both. The data processing unit 230 has built-in dimensional analysis software, which includes a cross-sectional dimension analysis module, a hole position dimension analysis module, and a straightness analysis module. The cross-sectional dimension analysis module compares the door frame outline scanned by the 3D vision camera 210 with a standard outline, calculating the dimensional deviations at key points of the cross-section. The hole position dimension analysis module processes the hole position data collected by the laser displacement sensor 220, calculating parameters such as the diameter and position of the mounting holes. The straightness analysis module processes the data collected by the laser displacement sensor 220 along the long side of the door frame, calculating the straightness error of the profile.

[0032] The reference calibration mechanism 300 includes a calibration block 310, a calibration block drive device 320, and a calibration control system 330. The calibration block 310 is a precision-machined standard part whose dimensions and geometric tolerances are completely consistent with the assembly reference of the A158 vehicle body, with a machining accuracy of ±0.005mm. The calibration block 310 is mounted on the output end of the calibration block drive device 320, which is either a cylinder or an electric cylinder, capable of driving the calibration block 310 to switch between a standby position and a working position.

[0033] The calibration control system 330 maintains signal connections with the positioning pin position sensor of the modular assembly fixture 100, and the camera and sensors of the fully automatic detection system 200. When benchmark calibration is required, the calibration control system 330 first controls the calibration block drive device 320 to push the calibration block 310 to the working position, and then controls the fully automatic detection system 200 to scan and measure the calibration block 310 to obtain the deviation value between the current fixture positioning benchmark and the detection system detection benchmark. Finally, based on this deviation value, the calibration control system 330 automatically adjusts the coordinate origin of the fully automatic detection system 200 to achieve synchronous calibration of the two benchmarks.

[0034] Example 2: Quick assembly method for changing multiple door frame models This embodiment describes in detail the specific operation process of using the device of the present invention for rapid replacement and assembly of multiple door frame models.

[0035] When the production schedule requires switching from one door frame model to another (e.g., from the front left door frame to the front right door frame), the operator first removes the positioning module 120 currently mounted on the universal base 110. The removal process is as follows: the operator manually releases the locking hook of the quick-change interface 111 from the locking groove on the bottom surface of the module base plate 121, and then lifts the positioning module 120 upwards, causing the mating boss on the bottom surface of the module base plate 121 to disengage from the positioning hole of the quick-change interface 111, thus completing the removal. The entire removal process takes no more than 2 minutes.

[0036] Next, the operator selects the positioning module 120 adapted to the new door frame model (in this example, the positioning module adapted to the front right door frame) and places it on top of the universal base 110, aligning the mating boss on the bottom surface of the module base plate 121 with the positioning hole of the quick-change interface 111. Then, the operator presses down on the positioning module 120, causing the mating boss to fully insert into the positioning hole, while the locking hook and locking groove automatically engage and lock. The entire installation process takes no more than 3 minutes.

[0037] After the positioning module 120 is installed, the operator adjusts the position and diameter of the adjustable positioning pin 122 according to the reference hole position and diameter specifications of the new door frame model. Specifically, the operator first loosens the locking nut of the positioning pin 122, moves the positioning pin 122 along the slide groove on the module base plate 121 to the target position, and then tightens the locking nut to fix it. If the diameter of the reference hole of the door frame is φ8mm, then a pin body with a diameter of φ8mm is selected; if the diameter is φ10mm, then a pin body with a diameter of φ10mm is selected. The replacement of the pin body is achieved through threaded connection, which is simple and quick to operate.

[0038] After the positioning pin 122 is adjusted, the operator pre-adjusts the elastic clamping mechanism 123, adjusting the initial angle of the clamping arm and the pre-tightening force of the elastic element to ensure that the clamping mechanism can apply appropriate clamping force to the door frame—ensuring that the door frame does not shift during assembly, and that the door frame does not deform due to excessive pressure.

[0039] After the installation and adjustment of the positioning module 120 are completed, the reference calibration mechanism 300 is started to perform reference calibration. The calibration control system 330 automatically controls the calibration block drive device 320 to push the calibration block 310 from the standby position to the working position. After the calibration block 310 is in place, the fully automatic detection system 200 is automatically started—the 3D vision camera 210 performs an overall contour scan of the calibration block 310, and the laser displacement sensor 220 performs precise measurements of the key dimensions of the calibration block 310. The data processing unit 230 compares the scan and measurement results with the standard dimension data of the calibration block 310 and calculates the deviation value between the fixture positioning reference and the detection system detection reference in the current state. Subsequently, the calibration control system 330 automatically corrects the coordinate origin of the fully automatic detection system 200 according to the deviation value, completing the synchronous calibration of the dual-end references. The total time for the entire changeover and calibration operation is approximately 15 minutes.

[0040] After the benchmark calibration is completed, the door frame assembly can begin. The operator places the door frame workpiece to be processed on the positioning module 120, aligning the benchmark hole of the door frame and inserting the adjustable positioning pin 122. Then, the operator or the automatic control system drives the clamping arm of the elastic clamping mechanism 123 to swing downwards, causing the clamping head to press against the upper surface of the door frame, fixing the door frame onto the positioning module 120. At this time, the door frame maintains the correct spatial position and posture under the joint constraint of the positioning pin 122 and the elastic clamping mechanism 123. Actual measurement verification shows that the basic assembly gap of the door frame assembled using the device of this invention is stably controlled within 0.2mm, fully meeting the process requirements.

[0041] Example 3: Fully Automated Dimension Inspection Process This embodiment describes in detail the specific process of using the device of the present invention to perform fully automatic dimensional inspection of the assembled door frame.

[0042] After the door frame is assembled and fixed on the modular assembly fixture 100, the operator starts the fully automatic inspection program through the human-machine interface of the data processing unit 230. Once the inspection program is started, the fully automatic inspection system 200 automatically executes the following inspection steps according to the preset inspection path and parameters: The first step is a full-area scan by the 3D vision camera 210. The 20-megapixel 3D vision camera 210 performs a complete scan of the entire outline of the door frame from directly above. The exposure time, gain, and other parameters of the 3D vision camera 210 are automatically optimized based on the surface color and reflective properties of the door frame to ensure clear image data. After scanning, the 3D vision camera 210 transmits the image data to the data processing unit 230 in real time.

[0043] The second step involves precision measurement by the laser displacement sensor 220. A three-dimensional motion platform moves the laser displacement sensor 220 along a preset detection path, sequentially acquiring high-precision dimensions of the door frame's cross-sectional contour, mounting hole positions, and the long side of the profiles. In the cross-sectional detection stage, the laser displacement sensor 220 scans point-by-point along multiple key cross-sectional contour lines of the door frame, acquiring the three-dimensional coordinate data of each measurement point. In the hole position detection stage, the laser displacement sensor 220 acquires multiple measurement points around the edge of each mounting hole, and calculates the actual diameter and center position of the mounting hole through fitting. In the straightness detection stage, the laser displacement sensor 220 acquires multiple measurement points at equal intervals along the long side of each profile of the door frame, and calculates the straightness error by calculating the deviation of each measurement point relative to the baseline. All measurement data from the laser displacement sensor 220 is transmitted to the data processing unit 230 in real time.

[0044] The third step involves automatic analysis and judgment by the data processing unit 230. After receiving all data from the 3D vision camera 210 and the laser displacement sensor 220, the built-in analysis program automatically performs the following processing: The cross-sectional dimension analysis module compares the door frame outline data obtained by the 3D vision scan with the standard CAD model, calculates the actual dimensional deviation of each key point of the cross-section, and compares it with the ±0.2mm cross-sectional tolerance standard to determine whether each item is qualified. The hole position dimension analysis module processes the hole position data collected by the laser displacement sensor 220, calculates the actual diameter and center position coordinates of each mounting hole, compares them with the standard values, and compares them with the ±0.1mm hole position tolerance standard to determine whether each item is qualified. The straightness analysis module processes the data collected by the laser displacement sensor 220 along the long side of the door frame, calculates the straightness error of each profile, and compares it with the preset straightness tolerance standard.

[0045] The fourth step is to automatically generate an electronic inspection report. After the analysis and judgment of all dimensional data are completed, the data processing unit 230 automatically generates a standardized electronic inspection report. The inspection report includes: workpiece number, model information, production time, measured value, standard value, deviation value, judgment result (pass / out of tolerance), the amount of deviation for out-of-tolerance items, and a comprehensive judgment conclusion (overall pass / fail). The inspection report is stored in a common electronic document format (such as PDF or Excel) on the hard drive of the data processing unit 230, and can also be uploaded to the enterprise's quality management system via the network.

[0046] Actual testing has verified that the device of this invention performs fully automated dimensional inspection of a single door frame in less than 3 minutes from start to report generation, which is more than 5 times more efficient than traditional manual inspection methods (≥15 minutes). The ±0.01mm detection accuracy of the laser displacement sensor ensures the accuracy and reliability of the measurement data, and the entire process requires no manual intervention, completely eliminating errors from manual reading and recording.

[0047] After the inspection is completed, qualified products are automatically released to proceed to the next process; out-of-tolerance products are automatically marked and warned, and the human-machine interface of the data processing unit 230 displays the specific location and amount of the out-of-tolerance items, prompting the operator to handle them.

[0048] Example 4: Working principle and calibration method of the reference calibration mechanism This embodiment describes in detail the structure, working principle, and specific calibration method of the reference calibration mechanism 300.

[0049] The core component of the benchmark calibration mechanism 300 is the calibration block 310. The calibration block 310 is made of high-strength alloy steel and precision-ground. Its external dimensions, positional tolerances, flatness, and perpendicularity of key features are all controlled within ±0.005mm. The dimensions of the calibration block 310 are completely consistent with the assembly benchmark of the A158 vehicle body—that is, the coordinate values ​​of key elements such as positioning features and datum surfaces on the calibration block 310 are exactly the same as the coordinate values ​​of the corresponding assembly features on the A158 vehicle body.

[0050] The calibration block 310 is mounted on the output end of the calibration block drive device 320. The calibration block drive device 320 is a precision electric cylinder with a repeatability of ±0.01mm. The calibration block drive device 320 is fixedly mounted on one side of the universal base 110, and its driving direction is horizontal. Driven by the calibration block drive device 320, the calibration block 310 can switch between a retracted standby position and an extended working position. In the standby position, the calibration block 310 retracts to one side, without affecting the assembly and inspection of the door frame; in the working position, the calibration block 310 moves above the modular assembly fixture 100, and its positioning features are within the detection coverage of the 3D vision camera 210 and the laser displacement sensor 220.

[0051] The calibration control system 330 is an independent industrial controller, which is connected to the positioning pin position sensor of the modular assembly fixture 100, the 3D vision camera 210 and laser displacement sensor 220 of the fully automatic detection system 200, the data processing unit 230 and the calibration block drive device 320 via signal lines.

[0052] The specific method for benchmark calibration is as follows: Once the door frame model change is completed and the new positioning module 120 is installed, the calibration control system 330 automatically starts the calibration program. First, the calibration control system 330 sends a control command to the calibration block drive device 320, driving the calibration block 310 to move from the standby position to the working position.

[0053] Once the calibration block 310 is in place, the calibration control system 330 sends a start signal to the fully automatic detection system 200. The 3D vision camera 210 scans the overall outline of the calibration block 310 to acquire the spatial coordinate data of each positioning feature on the calibration block 310. At the same time, the laser displacement sensor 220 performs precise measurements on the key dimensional features of the calibration block 310 (such as the diameter of the positioning hole, the flatness of the reference surface, and the relative positions between the features).

[0054] All data collected by the 3D vision camera 210 and the laser displacement sensor 220 are transmitted to the data processing unit 230 in real time. The data processing unit 230 compares and analyzes the measured data with the standard data of the calibration block 310 (pre-stored in the memory of the data processing unit 230) and calculates the following deviation values: (1) the translational and rotational deviations between the current detection coordinate system of the fully automatic detection system 200 and the standard coordinate system of the calibration block 310; (2) the deviation between the current positioning reference of the modular assembly fixture 100 and the standard reference of the calibration block 310.

[0055] Subsequently, the data processing unit 230 feeds back the calculated deviation value to the calibration control system 330. The calibration control system 330 automatically performs the following two calibration operations based on the deviation value: First, it corrects the origin of the detection coordinate system of the fully automatic detection system 200—translating and rotating the coordinate origins of the 3D vision camera 210 and the laser displacement sensor 220 as a whole, so that they completely coincide with the standard coordinate system of the calibration block 310; Second, if the deviation of the fixture positioning reference exceeds the allowable range, it adjusts the position of the positioning pin 122 or notifies the operator to manually correct it, ensuring that the fixture positioning reference is consistent with the standard reference of the calibration block 310.

[0056] After calibration, the calibration control system 330 controls the calibration block drive device 320 to return the calibration block 310 from the working position to the standby position, thus ending the entire calibration process. After calibration, the positioning reference of the modular assembly fixture 100 and the detection reference of the fully automatic detection system 200 are completely unified, and there is no longer any systematic reference offset between them.

[0057] Actual testing has verified that the integrated automatic benchmark calibration mechanism of this invention can automatically complete benchmark calibration within 2 minutes after each model change, and the residual deviation between the fixture positioning benchmark and the detection system benchmark after calibration is less than 0.01mm. Compared with the traditional process where there is an inherent deviation of more than 0.3mm between the fixture positioning benchmark and the vehicle body assembly benchmark, the benchmark calibration accuracy of this invention is improved by more than 30 times, fundamentally solving the industry problem of excessive gaps in door frame assembly.

[0058] Example 5: Mass Production Quality Traceability Method This embodiment describes in detail the specific method for achieving mass production quality traceability using the device of the present invention.

[0059] After the fully automated inspection system 200 completes dimensional inspection of each door frame and generates an electronic inspection report, the data processing unit 230 automatically stores the inspection report in its built-in database. Each inspection report contains the following complete information: workpiece number (uniquely identifying each door frame), door frame model (front left / front right / rear left / rear right), production date and time, operator's employee number, measured value, standard value, deviation value, judgment result, comprehensive judgment conclusion, and all raw data collected by the 3D vision camera 210 and laser displacement sensor 220.

[0060] Data storage adopts a structured database format, and all data is indexed according to fields such as workpiece number, production time, and model to facilitate subsequent retrieval and query.

[0061] Once a day's production is completed, quality management personnel can perform the following quality traceability operations through the human-machine interface of the data processing unit 230: Operation 1: Search by workpiece number. Quality management personnel enter the target workpiece number into the search interface, and the system automatically retrieves the complete inspection report for that workpiece from the database, displaying all dimensional data, judgment results, and original scanned images on the screen.

[0062] Operation 2: Query by time period. Quality management personnel select the start and end dates, and the system automatically lists a summary table of inspection results for all door frames produced within that time period, including statistical information such as total number, number of qualified, number of unqualified, and pass rate for each model.

[0063] Operation 3: Filter by tolerance type. Quality management personnel can select specific tolerance types (such as cross-sectional dimension tolerance, hole position offset, straightness tolerance, etc.), and the system will automatically filter out all workpieces with that type of tolerance and sort them from largest to smallest tolerance amount, making it easier to prioritize the handling of the most serious quality problems.

[0064] When a batch of door frames has quality problems such as excessive gaps or misaligned holes, quality management personnel can trace the source of the problem and optimize the process by following these steps: The first step is to retrieve the original inspection data of the defective product. Enter the workpiece number of the defective product in the query interface, and the system will display the complete inspection report and original scan data of that workpiece.

[0065] The second step is to analyze the location and amount of the deviation. By reviewing the details of the deviation items in the inspection report and the original scan data, the specific location of the deviation (such as a specific section of the door frame, a specific mounting hole, or a specific profile section) and the specific value of the deviation are determined.

[0066] The third step is to locate the problematic process. The location of the defective part that deviates from the standard procedure is compared with the position of the positioning pin 122 and the elastic clamping mechanism 123 in the assembly process to determine whether the deviation is caused by positioning error, improper clamping force, or manufacturing error of the positioning module 120. For example, if the direction of the deviation in the position of a mounting hole is consistent with the offset direction of the positioning pin 122, the problem can be determined to originate from the positional deviation of the positioning pin 122; if the cross-sectional dimensions of a certain area of ​​the door frame deviate from the standard procedure, the problem can be determined to originate from uneven pressure of the elastic clamping mechanism 123.

[0067] The fourth step is to implement process optimization. Based on the results of the problem tracing, targeted process optimization measures are taken: if the problem is a deviation in the position of the positioning pin 122, the position of the positioning pin 122 is readjusted; if the problem is an improper clamping force, the preload of the elastic clamping mechanism 123 is adjusted or the elastic element is replaced; if the problem is a manufacturing error in the positioning module 120, the positioning module 120 is repaired or replaced.

[0068] The fifth step is to verify the optimization effect. After the process optimization is completed, continuous fully automated testing is carried out on the door frames produced subsequently. The test data before and after optimization are compared to verify the effectiveness of the optimization measures.

[0069] Through the aforementioned quality traceability and closed-loop process improvement procedures, manufacturing enterprises can achieve continuous improvement in the assembly quality of door frames and reduce the defect rate to a minimum.

[0070] Example 6: Specific Structure and Parameters of Key Components This embodiment further describes in detail the specific structure and preferred parameters of several key components in the device of the present invention.

[0071] Structure and parameters of the universal base 110: The universal base 110 is cast from HT250 high-strength cast iron and precision-machined after aging treatment. The universal base 110 has external dimensions of 1200mm × 800mm × 150mm (length × width × height), and the flatness of its upper surface is controlled within 0.05mm. The upper surface of the universal base 110 is machined with a quick-change interface 111, which includes 4 precision positioning holes and 8 locking slots. The 4 precision positioning holes are arranged in a rectangular array, with a diameter of φ20mm, a hole spacing of 600mm × 400mm, and a positional tolerance of ±0.02mm. The 8 locking slots are distributed around the 4 precision positioning holes, with 2 locking slots per positioning hole. The locking slots are T-slot structures with a width of 12mm.

[0072] The universal base 110 has six anchor bolt mounting holes with a diameter of φ18mm on its bottom, used to fix the universal base 110 to the production workshop floor with anchor bolts. Lifting rings are provided at the four corners of the universal base 110 for easy handling and installation using an overhead crane.

[0073] Structure and parameters of positioning module 120: Each positioning module 120's module base plate 121 is made of 45# steel and is precision machined after heat treatment. The bottom surface of the module base plate 121 is provided with 4 positioning bosses and 8 locking hooks. The position and diameter of the positioning bosses match the precision positioning holes of the universal base 110 (φ20mm, position tolerance ±0.02mm), and the position and shape of the locking hooks match the locking grooves of the universal base 110.

[0074] The upper surface of the module base plate 121 is machined with a positioning pin mounting groove according to the reference hole position of the corresponding door frame model. The groove is a straight groove with a width of 12mm and a length of 200mm. An adjustable positioning pin 122 is installed in the groove and its position can be adjusted by sliding along the groove. The adjustment range of the positioning pin 122 covers all possible reference hole position deviations of this door frame model.

[0075] The adjustable positioning pin 122 consists of three parts: a pin seat, a pin body, and a locking nut. The pin seat is a cuboid structure with a width matching the width of the slide groove (12mm), allowing it to slide within the groove. A φ12mm mounting hole for the pin body is located at the center of the pin seat, containing an internal thread. The pin body is cylindrical, with an external thread at the lower end matching the internal thread of the mounting hole, and a positioning working surface at the upper end. The pin body is available in two diameters: φ8mm and φ10mm, corresponding to two reference hole diameters in the door frame. The locking nut is fitted onto the external thread of the pin body. After the pin body is screwed into the pin seat, tightening the locking nut locks the pin body and pin seat together as one unit.

[0076] The elastic clamping mechanism 123 includes a clamping arm, a clamping head, a hinge seat, and an elastic element. The hinge seat is fixedly mounted on the upper surface of the module base plate 121. One end of the clamping arm is hinged to the hinge seat via a pin, allowing it to swing about the pin in a vertical plane. The other end of the clamping arm has a clamping head mounting hole. The clamping head is a cylindrical component made of polyurethane material, mounted at the end of the clamping arm, and in direct contact with the upper surface of the door frame. The elastic element is a compression spring, fitted into the middle part of the clamping arm, with one end connected to the clamping arm and the other end connected to the module base plate 121, providing a downward clamping force to the clamping arm. The preload of the elastic element can be adjusted by adjusting the initial compression of the compression spring, with an adjustment range of 50N to 200N.

[0077] Specifications of the 3D Vision Camera 210: The 3D Vision Camera 210 is an industrial-grade CMOS area scan camera with a resolution of 20 megapixels (5472×3648 pixels) and a pixel size of 2.4μm×2.4μm. The camera is equipped with a 12mm focal length industrial lens with a field of view of 45°×35°. At a working distance of 800mm, the field of view coverage is approximately 660mm×500mm, sufficient to cover the overall outline of even the largest door frames. The camera operates at a frame rate of 15fps, and the exposure time is adjustable from 10μs to 10s. The camera features a ring LED light source with a color temperature of 5000K and adjustable brightness.

[0078] Parameters of laser displacement sensor 220: The 220 laser displacement sensor is a point laser triangulation displacement sensor with a measurement range of ±10mm, a reference working distance of 50mm, a measurement accuracy of ±0.01mm, and a repeatability of ±0.002mm. The laser wavelength is 655nm (red visible light), and the laser power is 1mW (Class 2 laser product). The sensor's sampling frequency is 2kHz, meaning it can acquire 2000 measurement points per second. The sensor is mounted on a 3D motion platform with an X-axis travel of 800mm, a Y-axis travel of 600mm, and a Z-axis travel of 100mm. The motion accuracy of each axis is ±0.01mm, and the motion speed is adjustable from 0-100mm / s.

[0079] Structure and parameters of calibration block 310: The calibration block 310 is made of GCr15 bearing steel, and after vacuum quenching and deep cryogenic treatment, it is precision ground to achieve a surface hardness of HRC60-62. The calibration block 310 is a cuboid with dimensions of 200mm × 150mm × 80mm. The upper and side surfaces of the calibration block 310 are precision ground to achieve a flatness of 0.002mm and a surface roughness Ra≤0.1μm.

[0080] The calibration block 310 is equipped with multiple positioning features, including: four positioning holes (diameter φ10mm, positional tolerance ±0.003mm), two positioning reference surfaces (flatness 0.002mm, positional tolerance to the corresponding positioning hole ±0.005mm), and one V-shaped reference groove (groove width 20mm, symmetry 0.003mm). The dimensions and positional relationships of all the above positioning features are completely consistent with the corresponding features of the A158 model vehicle body assembly reference.

[0081] The bottom of the calibration block 310 has a mounting interface, through which it is fixedly connected to the output end of the calibration block drive device 320. The calibration block drive device 320 is a precision electric cylinder with a stroke of 150mm, a repeatability of ±0.01mm, and a maximum thrust of 500N.

[0082] Configuration of data processing unit 230: The data processing unit 230 is an industrial control computer, equipped with an Intel Core i7 processor (8 cores, 3.6GHz), 32GB DDR4 memory, a 1TB NVMe solid-state drive, and a 23-inch touchscreen display. The computer runs Windows 10 IoT Enterprise operating system and includes built-in door frame dimension inspection and analysis software. The software adopts a modular design, including image acquisition, laser data acquisition, 3D reconstruction, dimension analysis, report generation, and database management modules. The software supports data interface with the enterprise's MES (Manufacturing Execution System) and QMS (Quality Management System) to achieve automatic uploading and sharing of inspection data.

[0083] Industrial applicability This invention provides a modular assembly and dimensional inspection device for door frames, which can be widely used on door frame production lines in automobile manufacturing enterprises. The device achieves rapid switching between four door frame models on the same tooling through a modular quick-change design; it achieves fully automated, high-precision inspection of door frame dimensions through 3D vision and laser composite inspection technology; it unifies the assembly benchmark with the vehicle benchmark through an integrated automatic benchmark calibration mechanism; and it achieves full quality traceability through electronic storage of inspection data. This invention's device has advantages such as compact structure, simple operation, high inspection accuracy, fast changeover speed, and wide applicability. It effectively solves the long-standing pain points in automobile door frame production, such as slow changeover, inefficient inspection, and inconsistent benchmarks, and has good industrial practical value and broad market application prospects.

[0084] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A modular assembly and dimensional inspection device for door frames, characterized in that, The system includes a modular assembly fixture, which consists of a universal base and four sets of quick-change positioning modules. The four sets of positioning modules are adapted to four workpiece models: front left door frame, front right door frame, rear left door frame, and rear right door frame. The positioning modules can be quickly assembled and disassembled with the universal base through standardized quick-change interfaces. The fully automated inspection system includes a 3D vision camera, a laser displacement sensor, and a data processing unit. The 3D vision camera is used to scan the overall outline of the door frame, and the laser displacement sensor is used to collect data on the cross-sectional dimensions of the door frame, the dimensions of the mounting holes, and the straightness of the profiles. The data processing unit receives the data collected by the 3D vision camera and the laser displacement sensor, automatically determines whether the dimensions meet the tolerance standards, and automatically generates an electronic inspection report. A reference calibration mechanism, wherein the reference calibration mechanism has a built-in calibration block, and the shape and size of the calibration block are consistent with the vehicle body assembly reference; The reference calibration mechanism is used to automatically perform dual-end synchronous calibration of the positioning reference of the modular assembly fixture and the detection reference of the fully automatic detection system after the positioning module is replaced.

2. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The upper surface of the universal base is provided with the standardized quick-change interface, which includes a precision positioning hole and a locking groove; the bottom of the positioning module is provided with a positioning boss that matches the precision positioning hole and a locking hook that matches the locking groove; when the positioning boss is inserted into the precision positioning hole and the locking hook is engaged with the locking groove, the positioning module is fixedly connected to the universal base.

3. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, Each positioning module includes an adjustable positioning pin and an elastic clamping mechanism. The adjustable positioning pin is located on the upper surface of the positioning module and its position can be adjusted along a preset groove. The elastic clamping mechanism includes a clamping arm and an elastic element. One end of the clamping arm is hinged to the positioning module, and the other end is provided with a clamping head. The elastic element provides continuous pressure to the clamping arm. The positioning pin and the elastic clamping mechanism together constrain the spatial position of the door frame.

4. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The 3D vision camera is mounted directly above the modular assembly fixture and is used to perform a one-time complete scan of the overall outline of the door frame; the laser displacement sensor is mounted on a three-dimensional motion platform and can move along the X-axis, Y-axis and Z-axis to perform point-by-point high-precision measurement of the door frame cross-sectional outline, mounting hole positions and profile long side.

5. The modular assembly and dimensional inspection device for a door frame according to claim 4, characterized in that, The data processing unit has a built-in dimensional analysis program, which includes a cross-sectional dimensional analysis module, a hole position dimensional analysis module, and a straightness analysis module. The cross-sectional dimensional analysis module is used to compare the door frame outline obtained by the 3D vision camera with a standard outline and calculate the cross-sectional dimensional deviation. The hole position dimensional analysis module is used to process the hole position data collected by the laser displacement sensor and calculate the diameter and position of the mounting holes. The straightness analysis module is used to process the data collected by the laser displacement sensor along the long side of the door frame and calculate the straightness error of the profile. The data processing unit automatically compares each dimension with the preset tolerance standard and generates an electronic inspection report.

6. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The reference calibration mechanism also includes a calibration block driving device and a calibration control system. The calibration block driving device is used to drive the calibration block to switch between a standby position and a working position. The calibration control system is used to control the automatic calibration process of the calibration block and correct the origin of the detection coordinate system of the fully automatic detection system according to the calibration results.

7. The modular assembly and dimensional inspection device for a door frame according to claim 6, characterized in that, When the reference calibration mechanism performs automatic calibration, the calibration block driving device drives the calibration block from the standby position to the working position. The fully automatic detection system scans and measures the calibration block. The data processing unit compares the measured data with the standard data of the calibration block and calculates the deviation value. The calibration control system automatically corrects the origin of the detection coordinate system of the fully automatic detection system according to the deviation value, thus completing the synchronous calibration of the positioning reference of the modular assembly fixture and the detection reference of the fully automatic detection system.

8. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The positioning module can be quickly disassembled and connected to the universal base through the standardized quick-change interface; the door frame is assembled by the modular assembly fixture.

9. The modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The electronic inspection report includes the workpiece number, model information, production time, measured value of each dimension, deviation value, judgment result, and comprehensive judgment conclusion.

10. A modular assembly and dimensional inspection device for a door frame according to claim 1, characterized in that, The data processing unit also includes a database storage module, which stores the complete electronic inspection report and original collected data for each door frame. The database storage module supports data retrieval and export by workpiece number, production time period, and out-of-tolerance type for quality traceability and process optimization analysis.

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