Ram structure integrated with line laser scanning and in-situ measurement and compensation machining method

Abstract

The present application discloses a ram structure integrated with line laser scanning and an in-situ measurement and compensation machining method, and belongs to the technical field of machining equipment. In view of the low offline measurement accuracy in the prior art, the ram structure integrated with line laser scanning integrates a line laser measurement system in the ram body, and the workpiece can complete the closed loop of "machining-in-situ measurement-compensation re-machining" in one clamping, eliminating the positioning error of secondary clamping. The synchronous trigger module triggers collection according to the grating displacement signal, so that the image strictly corresponds to the actual position of the ram body. Based on the mechanical micro-displacement vector, double-frame rigid mapping is performed and transient noise is removed, high signal-to-noise ratio profile data is obtained under complex working conditions, compensation instructions are automatically generated after comparing the actual measurement point cloud with the CAD model to drive fine machining, and the cycle is executed until the product is qualified.

Description

Technical Field

[0001] This invention relates to the field of machining equipment technology, and in particular to a slide ram structure with integrated line laser scanning and its in-situ measurement and compensation machining method. Background Technology

[0002] In the CNC machining of large, heavy, or high-precision parts, the workpieces are typically characterized by large dimensions, complex curved surfaces, long clamping times, and uneven distribution of machining allowances. To ensure the final dimensional accuracy, existing processes often require multiple cycles of "machining-measurement-remachining".

[0003] If the workpiece is removed from the machine tool for off-machine measurement, it will not only increase the time for hoisting, transportation and secondary clamping, but may also cause workpiece damage, deformation or loss of reference during the process, thereby affecting the machining accuracy and production efficiency.

[0004] To overcome the shortcomings of external measurement, in-situ measurement technology is gradually being applied to CNC machine tools. Common solutions include contact probe measurement and external laser measurement. Although contact probes have a mature structure, their measurement efficiency is low, they are difficult to obtain complex curved surface contours at high density, and there is a risk of scratching the finished surface. External laser measurement devices have the advantages of being non-contact and highly efficient, but they are usually installed protruding in the machine tool's machining space, which can easily occupy the travel and interfere with tools, fixtures, or workpieces. At the same time, these devices are exposed to cutting fluid, oil mist, dust, and random reflections for a long time, resulting in high imaging noise, significant calibration drift, and insufficient measurement stability.

[0005] Therefore, a mechanism is needed to solve the problems of the above-mentioned in-situ measuring devices occupying processing space, being difficult to protect, being unstable due to on-site interference, and the difficulty in directly forming closed-loop compensation processing from the measurement results. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a sliding ram structure for integrated line laser scanning and its in-situ measurement and compensation processing method, so as to improve the above-mentioned problems.

[0007] This invention provides a sliding bolster structure for integrated line laser scanning, comprising: The slide body is slidably mounted on the machine tool, which has a CNC system. The slide body has a vertical receiving cavity inside, and the lower end of the receiving cavity has a measuring window facing the workpiece area. The measuring assembly includes a line laser and an industrial camera respectively disposed in a receiving cavity, wherein the line laser and the lens of the industrial camera are both facing the measuring window; A protective cover is provided at the measurement window and the protective cover can be opened and closed; The synchronous triggering module is independently externally deployed and is communicatively connected to the displacement feedback end of the CNC system of the machine tool and the industrial camera. The synchronous triggering module can respond to the real-time displacement feedback signal of the machine tool feed axis and synchronously trigger the industrial camera to acquire laser stripe images. The data processing module is independently externally deployed and communicates with the industrial camera and the CNC system of the machine tool. The data processing module can output machining compensation amount or compensation command to the CNC system of the machine tool according to the pre-stored calibration parameters and the actual displacement of the slide body.

[0008] The present invention also provides an in-situ measurement and compensation processing method for the above-mentioned ram structure, comprising the following steps: S1. Initial system calibration: Control the slide body to move at known small step sizes and acquire images of standard parts, establish the calibration relationship between image pixel coordinates, camera coordinates and machine tool physical coordinates, and pre-store the calibration parameters in the data processing module to provide a reference for the spatial positioning of all subsequent images; S2. Pre-measurement rapid calibration: Using the standard parts set on the machine tool worktable as a reference, make minor corrections to the calibration relationship established in S1 to compensate for systematic errors caused by temperature drift, thermal deformation of the slide body, or installation offset, and ensure the accuracy of the calibration relationship during formal measurement. S3. Synchronous motion scanning: Based on the calibration relationship after slight correction, the slide body is controlled to drive the measuring component to move relative to the workpiece along the preset scanning path. During this process, the synchronous trigger module obtains the actual displacement feedback signal of the machine tool feed axis in real time. Whenever the slide body moves a preset displacement interval, the industrial camera is synchronously triggered to collect a frame of laser stripe image, so that the image acquisition time strictly corresponds to the actual physical position of the slide body, thereby collecting a continuous frame sequence. S4. Extract mechanical micro-displacement vector: Combine the continuous frame sequence with the displacement feedback data of the machine tool's CNC system to calculate the actual relative displacement of the slide body during the acquisition of two adjacent frames. S5, Dual-Frame Rigid Mapping and Denoising: Based on the actual relative displacement and the slightly corrected calibration relationship established by S2, adjacent frame images are mapped to the same spatial reference system, and noise points that do not conform to the rigid motion law are removed to eliminate interference introduced by cutting fluid splashing, oil mist scattering and random surface reflection, and obtain the contour features of each frame. S6. Data Reconstruction and Deviation Identification: The contour features of each frame are spliced ​​together in the order of actual displacement to reconstruct a three-dimensional point cloud model of the workpiece in place. The point cloud model is then compared with the CAD design model of the workpiece to determine the distribution of dimensional deviations and calculate the machining compensation amount. S7. Closed-loop execution compensation machining: The machining compensation amount is converted into CNC execution instructions, and the CNC system of the machine tool drives the machine tool to perform subsequent compensation machining until the workpiece size meets the design requirements, thus completing the in-situ measurement and compensation machining.

[0009] As a further improvement of the present invention, in S5, the determination criteria for the dual-frame pixel rigid mapping and denoising are as follows: During the point cloud data acquisition process, let two adjacent frames in the image sequence be... ,in This indicates the pixel coordinates of the Nth frame image. The original grayscale value at that location. The known displacement vector fed back by the machine tool's CNC system. The pixel rigid mapping transformation T established with the calibration will transform the pixels in the Nth frame. Theoretical predicted position mapped to the N+1th frame image plane The expression is:

[0010] Calculate the absolute grayscale difference between two frames after mapping and alignment. The expression is:

[0011] The system presets a grayscale tolerance threshold ε, which characterizes the normal grayscale fluctuation space caused by sensor imaging noise or minor geometric shifts. To reduce false positives, a local neighborhood consistency check is introduced: if more than 70% of the neighboring points within a 3×3 area around a pixel also satisfy the condition that the grayscale difference is less than ε, then it is determined to be a reliable feature. The logic for executing the judgment criterion is as follows: If satisfied If ≤ε and the local neighborhood consistency requirement is met, then the pixel is determined to be... The grayscale evolution pattern in the two consecutive frames conforms to the rigid displacement process, confirming it as the true contour feature of the workpiece surface, and thus it is retained. If satisfied If the ε or local neighborhood consistency requirement is not met, then the pixel is determined to be... The sudden change in grayscale does not conform to the grayscale evolution law during rigid displacement, confirming it as interference caused by cutting fluid droplets, dust, or random reflections. The system marks this point as noise and removes it, excluding it from subsequent point cloud 3D reconstruction.

[0012] Compared with the prior art, the present invention has at least the following advantages: 1. Achieve strict synchronization between image acquisition and the physical position of the slide body: The displacement feedback signal of the machine tool feed axis is obtained in real time through the synchronization trigger module. Whenever the slide body moves at a preset displacement interval, the industrial camera is triggered to acquire a frame of laser stripe image, so that the image acquisition time strictly corresponds to the actual physical position of the slide body. This fundamentally eliminates the problem of inconsistent frame spacing caused by uneven speed during the acceleration and deceleration phase of the slide body in the traditional timed trigger method, and provides a reliable data foundation for subsequent high-precision 3D reconstruction.

[0013] 2. Eliminate cumulative errors in 3D stitching: By calculating the actual relative displacement of the slide body during the acquisition of two adjacent frames based on the displacement feedback data of the machine tool's CNC system, and performing frame stitching with the actual displacement rather than the preset value, the deformation of the 3D model caused by the accumulation of small deviations between the preset displacement interval and the actual displacement frame by frame is avoided, which significantly improves the overall accuracy of in-situ measurement.

[0014] 3. Effective removal of noise interference in the in-situ measurement environment: By using the rigid motion law between adjacent frame images and the gray-scale difference value and neighborhood consistency condition to determine feature points, it can accurately distinguish between real feature points and noise points introduced by cutting fluid splash, oil mist scattering and random surface reflection. High-reliability noise reduction is achieved without relying on additional hardware filtering devices, ensuring the purity of measurement data in complex processing environments.

[0015] 4. Balancing calibration accuracy and measurement efficiency: A complete coordinate mapping relationship is established through initial system calibration. Before formal measurement, the calibration relationship is slightly corrected using standard parts to compensate for system errors caused by temperature drift, thermal deformation of the slide body, or installation offset. This ensures calibration accuracy while avoiding the time loss caused by performing a complete calibration process before each measurement, thus achieving a balance between accuracy and efficiency.

[0016] 5. Achieve closed-loop integration of measurement and compensation machining: By comparing the reconstructed in-situ 3D point cloud model with the workpiece CAD design model, the distribution of dimensional deviations is determined and the machining compensation amount is calculated. Then, the compensation amount is converted into CNC execution instructions to drive the machine tool to perform subsequent compensation machining, forming a complete closed loop of "measurement-analysis-compensation". There is no need to disassemble the workpiece and transfer it to the coordinate measuring machine, which shortens the machining cycle and improves machining consistency. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram showing the overall structural layout of the present invention; Figure 2 This is a perspective view of the measuring component of the present invention; Figure 3 This is a cross-sectional view of the measuring component of the present invention; Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle; Figure 5 This is a diagram showing the optical path arrangement for the measurement in this invention; Figure 6 This is a flowchart of the closed-loop control for in-situ measurement and compensation processing of the present invention. Figure 7 This is a block diagram showing the hardware connection and signal flow of the control system of the present invention.

[0019] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: Workbench 1; Workpiece 2; Measuring component 3; Slide 4; Slide body 5; Crossbeam 6; Column 7; CNC system 8; Measurement control terminal 9; Data processing module 10; Synchronous triggering module 11; Grating ruler 12; Line laser 13; Transparent protective window 14; Spindle 15; Industrial camera 16; Mounting base 17; Protective cover 18. Detailed Implementation

[0020] The technical solutions of the 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 of 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.

[0021] Example 1 like Figure 1 As shown, this embodiment provides a sliding ram structure for integrated line laser scanning, including: The slide body 5 is slidably mounted on the machine tool, which has a CNC system 8. The slide body 5 has a vertical receiving cavity inside, and the lower part of the receiving cavity has a measuring window facing the workpiece 2 area. The measuring component 3 includes a line laser 13 and an industrial camera 16 respectively disposed in the receiving cavity, wherein the lenses of the line laser 13 and the industrial camera 16 are both facing the measuring window; A protective cover 18 is provided at the measurement window and the protective cover 18 is openable and closable. The synchronous trigger module 11 is independently externally deployed and is communicatively connected to the displacement feedback end of the CNC system 8 of the machine tool and the industrial camera 16. The synchronous trigger module 11 can respond to the real-time displacement feedback signal of the machine tool feed axis and synchronously trigger the industrial camera 16 to acquire laser stripe images. The data processing module 10 is independently externally deployed and is communicatively connected to the industrial camera 16 and the CNC system 8 of the machine tool.

[0022] The data processing module 10 is used to compare the reconstructed in-situ 3D point cloud model of workpiece 2 with the CAD design model, calculate the dimensional deviation distribution, and convert the dimensional deviation distribution into tool compensation amount, local allowance correction amount, or subsequent finishing path correction amount. The data processing module 10 stores camera intrinsic parameters, distortion coefficients, laser plane parameters, hand-eye calibration matrix between the camera coordinate system and the machine tool coordinate system, and displacement-pixel mapping parameters. The data processing module 10 can perform rigid mapping, denoising, contour extraction, and point cloud reconstruction on the acquired laser image based on the pre-stored calibration parameters and the actual displacement during adjacent frame acquisition, and output machining compensation amount or compensation command to the CNC system of the machine tool.

[0023] As a preferred embodiment of the present invention, such as Figures 2-4 As shown, the protective cover 18 is detachably installed on the measuring window by means of threaded engagement. The protective cover 18 has a manually rotating opening and closing structure. Under the cutting and machining conditions, it is screwed tightly closed to form a full-seal protection for the optical devices in the cavity. Before entering the measurement process, it is screwed open to expose the measuring window.

[0024] As a preferred embodiment of the present invention, such as Figures 2-4 As shown, a transparent protective window 14 is also provided in the receiving cavity. The transparent protective window 14 is located above the protective cover 18. The transparent protective window 14 is made of wear-resistant transparent material. The transparent protective window 14 is embedded in the measuring window and is sealed to the receiving cavity to prevent cutting fluid and dust from entering the receiving cavity.

[0025] As a preferred embodiment of the present invention, such as Figures 2-5 As shown, it also includes a mounting base 17. The line laser 13 and the industrial camera 16 are respectively fixed in the receiving cavity by the mounting base 17. The mounting base 17 is a rigid block. The line laser 13 and the industrial camera 16 are each fixed on the mounting base 17 to ensure that their relative postures are fixed. The laser plane of the line laser 13 and the imaging optical axis of the industrial camera 16 form a 30° fixed triangulation angle, which constitutes the line laser triangulation measurement optical path. The fixed distance between the line laser 13 and the industrial camera 16 is the baseline.

[0026] As a preferred embodiment of the present invention, such as Figure 7 As shown, the synchronous triggering module 11 includes a displacement feedback acquisition unit, a trigger control unit, and a camera exposure output unit. The displacement feedback acquisition unit can acquire feedback signals from the grating ruler 12 or servo encoders. The trigger control unit can generate trigger signals according to preset displacement intervals or preset scanning paths. The camera exposure output unit can output exposure trigger signals to the industrial camera 16. The feed axis of the ram body 5 is equipped with a high-precision closed grating ruler 12. The grating ruler 12 acquires the feed displacement of the ram body 5 in real time and transmits the displacement pulse signals to the CNC system 8 of the machine tool. The CNC system 8 of the machine tool establishes a communication connection with the synchronous triggering module 11. The synchronous triggering module 11 receives the feedback signals from the grating ruler 12 in real time and generates trigger commands according to preset displacement intervals or scanning paths. When the ram body 5 moves to the specified scanning position, the synchronous triggering module 11 outputs an exposure trigger signal to the industrial camera 16, realizing the synchronous linkage of displacement signals, laser emission, and image acquisition.

[0027] This section provides supplementary explanations of the components and connections involved in this embodiment. The components mainly include a worktable 1, a measuring component 3, a slide block 4, a ram body 5, a crossbeam 6, a column 7, a CNC system 8, a measurement control terminal 9, and a spindle 15. The column 7 is fixedly mounted on the worktable 1, the crossbeam 6 is fixedly mounted on the side of the column 7, the slide block 4 is slidably mounted on the side of the crossbeam 6, the ram body 5 is slidably mounted on the slide block 4, and the measuring component 3 and the spindle 15 are both located at the bottom of the ram body 5. The measurement control terminal 9 is an independently external device and establishes a communication connection with the CNC system 8.

[0028] Example 2 like Figure 6 As shown, this embodiment provides an operation method for a ram structure, including the following steps: S1. Initial system calibration: Control the slide body 5 to move at known small step size and collect images of standard parts, establish the calibration relationship between image pixel coordinates, camera coordinates and machine tool physical coordinates, and pre-store the calibration parameters in the data processing module 10 to provide a reference for the spatial positioning of all subsequent images. S2. Pre-measurement rapid calibration: Before the formal measurement, the calibration relationship established in S1 is slightly corrected using the standard parts set on the machine tool worktable 1 to compensate for systematic errors caused by temperature drift, thermal deformation of the slide body 5 or installation offset, and to ensure the accuracy of the calibration relationship during the formal measurement. S3. Synchronous motion scanning: Based on the system after calibration of S1 and S2, the slide body 5 is controlled to drive the measuring component 3 to move relative to the workpiece 2 along the preset scanning path. During this process, the synchronous trigger module 11 obtains the actual displacement feedback signal of the machine tool feed axis in real time. Whenever the slide body 5 moves a preset displacement interval, the industrial camera 16 is synchronously triggered to collect a frame of laser stripe image, so that the image acquisition time strictly corresponds to the actual physical position of the slide body 5. S4. Extract mechanical micro-displacement vector: For the continuous frame sequence acquired in S3, calculate the actual relative displacement of the slide body 5 during the acquisition of two adjacent frames based on the displacement feedback data of the CNC system 8 of the machine tool. S5, Dual-Frame Rigid Mapping and Denoising: Based on the actual relative displacement obtained in S4 and the calibration relationship established in S1, adjacent frame images are mapped to the same spatial reference system, and noise points that do not conform to the rigid motion law are removed to eliminate interference introduced by cutting fluid splashing, oil mist scattering and random surface reflection. S6. Data Reconstruction and Deviation Identification: Based on the frame-by-frame denoising and alignment completed in S5, the contour features of each frame are spliced ​​together according to the actual displacement order to reconstruct the in-situ three-dimensional point cloud model of workpiece 2. Then, the point cloud model is compared with the CAD design model of workpiece 2 to determine the distribution of dimensional deviations and calculate the processing compensation amount. S7. Closed-loop execution compensation machining: The machining compensation amount obtained in S6 is converted into CNC execution instructions, and the CNC system 8 of the machine tool drives the machine tool to perform subsequent compensation machining until the dimensions of workpiece 2 meet the design requirements.

[0029] In a preferred embodiment of the present invention, in S1, the process of establishing the calibration relationship includes: performing intrinsic parameter calibration and distortion correction on the industrial camera 16 to obtain the camera intrinsic parameter matrix and distortion coefficients; calibrating the spatial equation of the laser plane formed by the projection of the line laser 13 in the camera coordinate system; performing hand-eye calibration on the camera coordinate system and the machine tool coordinate system to obtain the hand-eye calibration matrix; controlling the slide body 5 to move at a known small step size and acquiring images of standard parts to establish a displacement-pixel mapping relationship; verifying the above calibration results using standard parts, and if the verification deviation exceeds a preset threshold, re-performing the corresponding calibration operation until the verification deviation meets the requirements.

[0030] In a preferred embodiment of the present invention, in S2, the standard component is a standard step block, a standard ball, or a standard gauge block; the micro-correction method is as follows: the data processing module 10 compares the measured size of the standard component with its theoretical size to obtain the deviation, and corrects the deviation based on the hand-eye calibration matrix or displacement-pixel mapping parameters.

[0031] In a preferred embodiment of the present invention, in S5, the criteria for determining noise removal are as follows: extract the grayscale value of the target pixel in the previous frame image, and determine the predicted position of the target pixel in the next frame image according to the rigid motion law. Extract the grayscale value at the predicted position, calculate the difference between the two grayscale values. If the grayscale difference is within the preset threshold tolerance range, and the neighborhood consistency condition is met in the local neighborhood centered on the predicted position, then the point is determined to conform to the rigid motion law and is a real feature point, and is retained. If the grayscale difference exceeds the preset threshold tolerance range, or does not meet the neighborhood consistency condition, then the point is determined to be a noise point and is removed.

[0032] In a preferred embodiment of the present invention, the local neighborhood is a 3×3 pixel neighborhood, and the neighborhood consistency condition is: the proportion of pixels whose grayscale difference values ​​within the local neighborhood meet the preset threshold tolerance range is not less than a preset ratio, and the preset ratio is adaptively adjusted according to the surface reflection characteristics of the workpiece 2.

[0033] Working Principle: This system performs a complete system calibration only once after the initial installation of the equipment, replacement of optical components, or major overhaul. First, a standard checkerboard calibration plate is fixed on the worktable 1. The slide body 5 is controlled to change multiple poses to acquire images, completing the intrinsic parameter calibration and distortion correction of the industrial camera 16. Then, standard spheres and standard step blocks are used to complete laser plane calibration. Combined with the machine tool's standard displacement stroke, hand-eye calibration between the camera and the machine tool is completed. Simultaneously, based on baseline B, 30° optical angle, and other inherent geometric parameters, a mapping relationship between displacement and pixels is established. After calibration, standard parts are used for accuracy verification. If the deviation exceeds a preset threshold, recalibration is performed. All qualified calibration parameters are uniformly stored in the data processing module 10. During mass production, the entire calibration process does not need to be repeated. After the workpiece completes rough machining on the machine, the machine tool is stopped, and the operator manually unscrews the protective cover 18 to initiate the pre-measurement rapid calibration process. Using standard step blocks, standard balls, or standard gauge blocks fixed on the machine tool worktable 1 as calibration benchmarks, the data processing module 10 compares the theoretical and measured dimensions of the standard parts, and makes minor corrections to the hand-eye calibration matrix and displacement-pixel mapping parameters to compensate for systematic errors caused by environmental temperature drift, thermal deformation of the slide body 5, and installation offset. After calibration, the CNC system 8 controls the slide body 5 to drive the measuring component 3 to move at a constant speed relative to the workpiece 2 along a preset scanning path. The synchronous trigger module 11 continuously triggers the industrial camera 16 to acquire images based on the real-time displacement signal of the grating ruler 12, obtaining multiple laser images with adjacent time frames. Based on the operating data, the CNC system 8 accurately calculates the mechanical micro-displacement vector between the slide body 5 and the workpiece during the acquisition of two adjacent image frames. The data processing module 10 combines the pre-stored calibration parameters and the measured micro-displacement vector to perform dual-frame pixel rigid mapping and noise reduction processing on adjacent image frames. First, the theoretical position of the pixel in adjacent images is calculated based on the rigid motion relationship. Then, the brightness difference value is calculated pixel by pixel, and the discrimination is completed by combining the 3×3 pixel neighborhood consistency rule: when the pixel brightness difference is within the preset threshold range, and no less than 70% of the pixels in the neighborhood meet the consistency requirements, the pixel is determined to be the real laser contour of the workpiece surface and is retained; for pixels with excessive brightness difference or discontinuous neighborhood features, they are determined to be transient noise generated by cutting fluid, oil mist, dust, or random reflection of the workpiece and are removed. This method uses the actual mechanical displacement of the machine tool as a constraint, and compared with the traditional image filtering method, it has stronger anti-interference ability under complex processing conditions. After the denoising process is completed, the data processing module 10 stitches the extracted effective contour features in sequence to reconstruct the in-situ three-dimensional point cloud model of the workpiece 2, and compares the measured point cloud model with the workpiece CAD design model to calculate the overall and local dimensional deviation distribution of the workpiece, and then converts the deviation data into tool compensation amount, local allowance correction amount, or finishing path correction amount.The system executes closed-loop control based on the dimensional judgment results: if the workpiece dimensional deviation is within the drawing tolerance range, the system automatically stores the measurement data and outputs an inspection report, and the entire process ends; if the workpiece has dimensional deviations, the data processing module 10 sends a compensation command to the CNC system 8, and the machine tool drives the spindle 15 to carry the tool to perform compensation finishing. After finishing, the rapid calibration, scanning measurement, and deviation judgment process is repeated again, and the cycle is executed until the workpiece dimensions are qualified. The entire process realizes a closed-loop operation of "machining-measurement-compensation-remachining" without disassembly or secondary clamping of the workpiece.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sliding ram structure for integrated line laser scanning, characterized in that, include: The slide body (5) is slidably mounted on the machine tool, which has a numerical control system (8). The slide body (5) has a vertical accommodating cavity inside, and the lower end of the accommodating cavity has a measuring window facing the workpiece (2) area. The measuring component (3) includes a line laser (13) and an industrial camera (16) respectively disposed in the receiving cavity, wherein the lenses of the line laser (13) and the industrial camera (16) are both facing the measuring window; A protective cover (18) is provided at the measurement window and the protective cover (18) can be opened and closed; The synchronous trigger module (11) is independently externally deployed and is connected to the displacement feedback end of the CNC system (8) of the machine tool and the industrial camera (16) respectively. The synchronous trigger module (11) can respond to the real-time displacement feedback signal of the machine tool feed axis and synchronously trigger the industrial camera (16) to collect laser stripe images. The data processing module (10) is independently externally deployed and communicates with the industrial camera (16) and the CNC system (8) of the machine tool. The data processing module (10) can output machining compensation amount or compensation command to the CNC system (8) of the machine tool according to the pre-stored calibration parameters and the actual displacement of the slide body (5). It also includes a mounting base (17), the line laser (13) and the industrial camera (16) are respectively fixed in the receiving cavity by the mounting base (17), and the laser plane of the line laser (13) forms a pre-angle with the imaging optical axis of the industrial camera (16); It also includes a grating ruler (12) disposed below the slide body (5), and the synchronous trigger module (11) includes a displacement feedback acquisition unit, a trigger control unit and a camera exposure output unit; the displacement feedback acquisition unit can acquire the feedback signal of the grating ruler (12) or the feedback signal of the servo encoder, the trigger control unit can generate a trigger signal according to a preset displacement interval or a preset scanning path, and the camera exposure output unit can output an exposure trigger signal to the industrial camera (16).

2. The ram structure according to claim 1, characterized in that, The protective cover (18) is detachably installed on the measuring window by means of threaded engagement.

3. The ram structure according to claim 1, characterized in that, The cavity is also provided with a transparent protective window (14), which is located above the protective cover (18) and is made of wear-resistant transparent material.

4. A method for in-situ measurement and compensation processing of a ram structure according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Initial system calibration: Control the slide body (5) to move according to known small step size and collect standard part images, establish the calibration relationship between image pixel coordinates, camera coordinates and machine tool physical coordinates, and store the calibration parameters in the data processing module (10) to provide a reference for the spatial positioning of all subsequent images; S2. Pre-measurement quick calibration: The calibration relationship established in S1 is slightly corrected based on the standard parts set on the machine tool worktable (1) to compensate for systematic errors caused by temperature drift, thermal deformation of the slide body (5) or installation offset, and to ensure the accuracy of the calibration relationship during formal measurement. S3, Synchronous motion scanning: Based on the calibration relationship after slight correction, the slide body (5) is controlled to drive the measuring component (3) to move relative to the workpiece (2) along the preset scanning path. During this process, the synchronous trigger module (11) obtains the actual displacement feedback signal of the machine tool feed axis in real time. Whenever the slide body (5) moves at a preset displacement interval, the industrial camera (16) is synchronously triggered to collect a frame of laser stripe image, so that the image acquisition time strictly corresponds to the actual physical position of the slide body (5), thereby collecting a continuous frame sequence. S4. Extract mechanical micro-displacement vector: Combine the continuous frame sequence with the displacement feedback data of the CNC system (8) of the machine tool to calculate the actual relative displacement of the slide body (5) during the acquisition of two adjacent frames; S5, Dual-Frame Rigid Mapping and Denoising: Based on the actual relative displacement and the slightly corrected calibration relationship established by S2, adjacent frame images are mapped to the same spatial reference system, and noise points that do not conform to the rigid motion law are removed to eliminate interference introduced by cutting fluid splashing, oil mist scattering and random surface reflection, and obtain the contour features of each frame. S6. Data reconstruction and deviation identification: The contour features of each frame are spliced ​​together in the order of actual displacement to reconstruct the in-situ three-dimensional point cloud model of the workpiece (2). The point cloud model is then compared with the CAD design model of the workpiece (2) to determine the distribution of dimensional deviations and calculate the processing compensation amount. S7. Closed-loop execution compensation machining: The machining compensation amount is converted into CNC execution instructions, and the CNC system (8) of the machine tool drives the machine tool to perform subsequent compensation machining until the workpiece (2) size meets the design requirements, that is, the in-situ measurement and compensation machining are completed.

5. The in-situ measurement and compensation processing method according to claim 4, characterized in that, In S1, the process of establishing the calibration relationship includes: performing intrinsic parameter calibration and distortion correction on the industrial camera (16) to obtain the camera intrinsic parameter matrix and distortion coefficient; calibrating the spatial equation of the laser plane formed by the projection of the line laser (13) in the camera coordinate system; performing hand-eye calibration on the camera coordinate system and the machine tool coordinate system to obtain the hand-eye calibration matrix; controlling the slide body (5) to move according to a known small step size and acquiring standard part images to establish a displacement-pixel mapping relationship; using the standard part to verify the above calibration results. If the verification deviation exceeds the preset threshold, the corresponding calibration operation is re-executed until the verification deviation meets the requirements.

6. The in-situ measurement and compensation processing method according to claim 4, characterized in that, In S2, the standard part is a standard step block, a standard ball, or a standard gauge block; the micro-correction method is: the data processing module (10) compares the measured size of the standard part with its theoretical size to obtain the deviation, and corrects it according to the deviation using the hand-eye calibration matrix or displacement-pixel mapping parameters.

7. The in-situ measurement and compensation processing method according to claim 4, characterized in that, In S5, the criteria for noise point removal are as follows: Extract the grayscale value of the target pixel in the previous frame image, and determine the predicted position of the target pixel in the next frame image according to the rigid motion law. Extract the grayscale value at the predicted position, calculate the difference between the two grayscale values. If the difference is within the preset threshold tolerance range, and the neighborhood consistency condition is met in the local neighborhood centered on the predicted position, then the point is determined to conform to the rigid motion law and is a real feature point, and is retained. If the difference exceeds the preset threshold tolerance range, or does not meet the neighborhood consistency condition, then the point is determined to be a noise point and is removed.

8. The in-situ measurement and compensation processing method according to claim 7, characterized in that, The local neighborhood is a 3×3 pixel neighborhood. The neighborhood consistency condition is that the proportion of pixels whose gray value difference within the local neighborhood meets the preset threshold tolerance range is not less than a preset ratio. The preset ratio is determined by the surface reflection characteristics of the workpiece (2).

Images