Graphite workpiece rotary machining lathe

Abstract

The invention relates to a graphite workpiece rotary machining lathe which comprises a truss robot used for automatic feeding, a first machine tool, a second machine tool, a processing unit, an execution unit and a plurality of image acquisition modules. The processing unit obtains edge contour information of the graphite workpiece based on the image data so as to calculate edge points of the graphite workpiece, and the gravity center position of the graphite workpiece is obtained through curve fitting of the edge points. And based on the association of the edge contour information and the gravity center position of the graphite workpiece and based on the mass of the graphite workpiece, the clamping point location and the clamping force of the graphite workpiece are calculated and judged, so that a control instruction is sent to an execution unit. According to the method, corresponding optimization of clamping point positions and clamping force is carried out in three stages, namely before working procedure machining, during working procedure machining and after working procedure machining, so that machining damage caused by particularity of materials of the graphite workpiece is avoided.

Description

Technical Field

[0001] This invention relates to the field of graphite processing, and more particularly to a rotary lathe for machining graphite workpieces. Background Technology

[0002] Graphite materials, due to their high temperature resistance, good electrical conductivity, and strong chemical stability, are widely used in high-end manufacturing fields such as aerospace, semiconductors, and new energy. With the development of industrial technology, higher requirements are placed on the processing accuracy, surface quality, and structural integrity of graphite workpieces, especially in rotary machining, where multi-stage cutting is required to achieve precise shaping of complex contours.

[0003] However, graphite is a typical brittle heterogeneous material with distinctive mechanical properties: low shear strength and high brittleness, making it prone to fracture when subjected to external impact or local stress concentration; poor heat resistance, and during continuous processing, the accumulation of cutting heat can lead to a local temperature increase in the workpiece, further reducing the material strength. If the clamping method is improper, it can easily cause workpiece deformation, cracks, or even breakage.

[0004] In existing technologies, rotary lathes for machining graphite workpieces generally suffer from the following problems:

[0005] Blindly selecting clamping points: Traditional lathes often use fixed-point clamping without considering the contour features, center of gravity, and thickness distribution of graphite workpieces. Clamping points are often set in the weak areas of the workpiece or the high-temperature processing area of ​​the previous process, which leads to stress concentration during clamping and causes workpiece damage.

[0006] Rigid clamping force control: Clamping force parameters are mostly preset fixed values, without dynamic adjustment based on workpiece quality, gripping contact area, and processing stage. When the clamping force is too large, it can easily crush brittle graphite; when it is too small, processing stability cannot be guaranteed, leading to workpiece displacement and affecting processing accuracy.

[0007] Insufficient adaptability to multiple processes: In multi-process machining, the contour, center of gravity and mass of graphite workpieces will change dynamically with the machining process. Existing technologies are unable to capture these changes in real time and optimize the clamping strategy in sync, resulting in cumulative errors due to improper clamping during process changeover, and even scrap.

[0008] Inappropriate clamping method: Most lathes use linear loading to apply clamping force, resulting in large instantaneous acceleration impact, which can easily cause micro-cracks in brittle graphite materials and reduce the mechanical properties of the workpiece.

[0009] Therefore, considering the characteristics of graphite materials, the requirements for rotary machining, and the above-mentioned problems, this invention proposes an automated lathe that can dynamically optimize clamping points and clamping forces and adapt to multi-process machining.

[0010] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a rotary lathe for machining graphite workpieces, comprising a gantry robot for automated loading, a first machine tool, and a second machine tool. The lathe also includes a processing unit, an execution unit, and several image acquisition modules positioned at various stages requiring clamping, flipping, or sequential processing to acquire image data of the graphite workpiece to be processed. The processing unit acquires the edge contour information of the graphite workpiece based on the acquired image data related to the workpiece, calculates the edge points, and obtains the center of gravity position of the workpiece through curve fitting. Then, based on the correlation between the edge contour information and the center of gravity position, and based on the mass of the workpiece, it calculates and determines the clamping point and clamping force, and sends control commands to the execution unit. An increase in the number of processing operations can lead to a temperature rise in the graphite workpiece within a short period due to repeated processing, further resulting in potential deformation or cracks during clamping. After processing, changes in the graphite workpiece's outer contour, center of gravity, and mass necessitate corresponding adjustments to the clamping point and clamping force. The method of the present invention can accurately match the shape characteristics and physical properties of graphite workpieces, avoid workpiece breakage and deformation caused by unreasonable clamping points or improper clamping force, and provide a stable clamping foundation for subsequent processing, especially suitable for the brittle characteristics of graphite materials.

[0012] According to a preferred embodiment, the processing unit optimizes the clamping points and clamping forces of the graphite workpiece based on the number of processes required for the workpiece to be processed and the stress-bearing parts of the workpiece corresponding to several processes. The processing unit compares the edge contour curve of the graphite workpiece after processing with the edge contour curve before processing to calculate the change in the outer contour of the graphite workpiece. Based on a pre-set target process, the processing unit determines whether the change in the outer contour of the graphite workpiece meets the process standard, and if it does, calculates the current center of gravity offset of the graphite workpiece to adjust the clamping points. This invention optimizes the clamping points and clamping forces in three stages: before, during, and after processing the graphite workpiece, avoiding processing damage caused by the special properties of the graphite workpiece material.

[0013] According to a preferred embodiment, the processing unit selects clamping points for the next process by avoiding the processing area of ​​the graphite workpiece in the previous process. Since processing the graphite workpiece causes the temperature of its stressed parts to rise, and graphite has poor heat resistance, excessively high temperatures can easily lead to a decline in its performance. Clamping under such conditions may result in deformation or cracking. Therefore, this invention, after one process, sets the clamping points in a relatively low-temperature region to avoid the area of ​​temperature rise, thus preventing damage to the graphite workpiece caused by clamping in high-temperature areas. Therefore, this invention ensures that the gantry robot clamps the graphite workpiece at a location with high strength for each process.

[0014] According to a preferred embodiment, the processing unit adjusts the clamping force parameters of the gantry robot's gripper based on the contact area between the gripper and the graphite workpiece at several selected clamping points and the mass of the graphite workpiece. Furthermore, the processing unit sets the control command for the clamping force using a gradient loading method. Since a larger contact area between the gantry robot's gripper and the graphite workpiece requires a smaller clamping force, and a larger mass of the graphite workpiece requires a larger clamping force, this application adjusts the clamping force parameters based on the contact area and workpiece mass, and employs a gradient loading method to achieve dynamic matching between the clamping force and the workpiece characteristics. A larger contact area and smaller mass result in a smaller clamping force, and vice versa, preventing excessive clamping force from crushing the workpiece or insufficient clamping force from causing loosening. The gradient loading method reduces instantaneous force impact, making it particularly suitable for brittle materials such as graphite, and lowering the risk of workpiece breakage caused by rigid loading.

[0015] According to a preferred embodiment, the processing unit performs a Boolean intersection operation between the model of the gantry robot's gripper and the edge contour curve of the graphite workpiece to generate a polygonal boundary of the contact area, and obtains the area of ​​the polygonal boundary as the contact area. This invention accurately calculates the contact area between the gripper and the workpiece through Boolean intersection operations, providing high-precision data support for clamping force adjustment. Accurate contact area data ensures the scientific validity of the clamping force parameter calculation, avoiding insufficient or overloaded clamping force due to errors in contact area estimation, and further improving the reliability of the clamping scheme.

[0016] According to a preferred embodiment, the processing unit generates control commands for gradient loading clamping force based on the adjustment results of the clamping force parameters. The processing unit generates a force change process that causes the gripper to smoothly start, then move at a constant speed, and finally smoothly finish. Gradient loading refers to a curved force change process where the execution unit controls the gripping speed to increase and then decrease. Gradient loading clamping force control (curved force change with initial increase and subsequent decrease) avoids the instantaneous acceleration impact of linear loading. The constant acceleration of linear loading easily leads to stress concentration and cracking in brittle materials, while the smooth start-constant speed-smooth finish force change process allows the clamping force to be evenly transmitted to the workpiece, reducing local stress peaks and effectively protecting the structural integrity of the graphite workpiece.

[0017] According to a preferred embodiment, the processing unit dynamically adjusts the clamping force based on the clamping points of the machine tool and the graphite workpiece, and based on the machining stage. When the graphite workpiece is in the roughing stage, the processing unit maintains clamping stability by increasing the clamping force at at least three clamping points with relatively large graphite workpiece thickness among the clamping points of the machine tool and the graphite workpiece. When the graphite workpiece is in the finishing stage, the processing unit reduces the clamping force by using at least two clamping points with relatively small graphite workpiece thickness among the clamping points of the machine tool and the graphite workpiece to avoid elastic deformation of the workpiece. Dynamically adjusting the clamping force and clamping points based on the machining stage (roughing / finishing) achieves clamping optimization under different machining requirements. During roughing, increasing the clamping force at thicker points resists large cutting forces, ensuring clamping stability and preventing workpiece displacement; during finishing, reducing the clamping force at thinner points reduces elastic deformation of the workpiece, improves surface finish accuracy, and balances machining efficiency and quality.

[0018] According to a preferred embodiment, after the gripper contacts the graphite workpiece, the processing unit adjusts the duration and magnitude of the clamping force based on the workpiece thickness to form a three-stage clamping. Adjusting the duration and magnitude of the clamping force based on the workpiece thickness to form a three-stage clamping (pre-tightening-relaxation-target force) effectively releases localized stress caused by assembly gaps and allows for stress redistribution within the workpiece. This solution is particularly suitable for clamping different thickness regions of graphite workpieces, avoiding stress concentration in a single clamping mode and further reducing the risk of workpiece deformation.

[0019] According to a preferred embodiment, the processing unit preprocesses the acquired image data to obtain a clear image of the graphite workpiece. The processing unit performs thresholding on the preprocessed image data to obtain the edge contour information of the graphite workpiece. The processing unit then fits several boundary points within the edge contour information using a Hough transform to obtain a continuous edge contour curve of the graphite workpiece after edge detection. Through image preprocessing (denoising and brightness equalization), thresholding, and Hough transform fitting of the continuous edge contour curve, the clarity and accuracy of the edge contour information are significantly improved. High-quality edge contour data provides a precise basis for subsequent center-of-gravity calculation and clamping point selection, improving the scientific nature of the clamping scheme from the source and reducing clamping deviations caused by image errors.

[0020] According to a preferred embodiment, the processing unit calculates the centroid coordinates of the region enclosed by the edge contour curve of the graphite workpiece based on pre-stored graphite workpiece density parameters and the continuous edge contour curve of the graphite workpiece to determine the center of gravity position of the graphite workpiece. The processing unit then obtains the thickness distribution of the graphite workpiece at the center of gravity position based on the determined center of gravity position and the edge contour curve at that position. The processing unit filters out regions near the center of gravity position where the thickness is greater than a preset threshold, and performs secondary filtering of these regions based on the curvature of the edge contour curve to select several candidate clamping points. The processing unit performs finite element simulation on the graphite workpiece based on the edge contour to simulate the stress on the candidate clamping points, and selects the region where the maximum stress is less than the compressive strength of graphite as the final clamping point based on the stress simulation results. This invention calculates the center of gravity position by combining density parameters, filters candidate points with acceptable thickness and suitable curvature, and verifies stress safety through finite element simulation to ensure that the strength of the final clamping point meets the requirements (maximum stress less than the compressive strength of graphite). This solution selects points based on both physical characteristics and mechanical properties, completely avoiding workpiece damage during processing due to insufficient point strength, and significantly improving clamping reliability and processing safety. Attached Figure Description

[0021] Figure 1 This is a simplified hardware topology diagram of a graphite workpiece rotary machining lathe according to a preferred embodiment of the present invention;

[0022] Figure 2 This is a simplified structural diagram of a gantry robot according to a preferred embodiment of the present invention;

[0023] Figure 3 This is a simplified structural diagram of a first or second machine tool according to a preferred embodiment of the present invention.

[0024] List of reference numerals

[0025] 100: Processing unit; 200: Execution unit; 310: Gantry robot; 320: First machine tool; 330: Second machine tool; 340: Image acquisition module. Detailed Implementation

[0026] The following is a detailed explanation with reference to the accompanying drawings.

[0027] Example 1

[0028] This invention provides a rotary lathe for machining graphite workpieces, which can be used for the automated rotary machining of workpieces, especially for the automated rotary machining of graphite workpieces. This invention focuses on the imperfections of existing lathe automation solutions and the unique characteristics of graphite machining in automated lathes, particularly considering the properties of graphite materials. Starting from the overall lathe structure design, and combining calculations from multiple dimensions such as lathe cutting efficiency, robotic arm efficiency, loading and unloading methods, and graphite workpiece data, a rotary lathe for machining graphite workpieces is constructed.

[0029] In the field of lathe machining, common problems include precise positioning, workpiece fit and positioning, and improving automation efficiency. With the continuous development of existing lathe technology and the constant innovation of equipment in various processes of automated machining, a mismatch has emerged between advanced equipment technology and outdated automation control methods. This is especially true in the machining of graphite workpieces. Because graphite is a brittle material with a heterogeneous structure, the clamping method and positions need to be carefully adjusted during multiple machining operations to prevent deformation or damage to the graphite workpiece.

[0030] Specifically, during the clamping process of graphite workpieces, it is necessary to ensure the clamping accuracy of the fixture to avoid workpiece breakage during the machining of the internal and external contours of the graphite. The clamping points must ensure that the force-bearing parts being machined are always located in the thickest and strongest positions of the graphite workpiece. In particular, during multi-process machining of graphite workpieces, it is essential to ensure the appropriateness of the clamping points and clamping force to prevent deformation or cracking of the graphite workpiece due to the increased temperature caused by multiple processing steps.

[0031] This embodiment relates to a rotary lathe for machining graphite workpieces. Preferably, the lathe includes a first machine tool 320, a second machine tool 330, and a gantry robot 310. The gantry robot 310 is used for loading and unloading materials from the first machine tool 320 and the second machine tool 330. Figure 3 As shown, the first machine tool 320 is used to perform a single operation on the graphite workpiece. The second machine tool 330 is used to perform a second operation on the graphite workpiece. Figure 2As shown, the gantry robot 310 includes an X-axis guide rail structure, a Y-axis guide rail structure, a Z-axis guide rail structure, and a servo system. The servo system is controlled by a system panel / handwheel. In manual mode, the operator operates the servo system using the axis selection, magnification, axial up / down, and left / right buttons on the system panel. In pulse mode, the operator operates the servo system using the axis selection and magnification buttons on the handwheel, and via a pulse transmitter. A material tray is provided between the first machine tool 320 and the second machine tool 330. The gantry robot 310 can clamp graphite workpieces from the material tray for transport to the corresponding machine tool. The process sequence is explained using the example of graphite workpieces needing to be processed in both the first machine tool 320 and the second machine tool 330.

[0032] A1: The gantry robot 310 clamps graphite workpieces from the tray to transport them to the first machine tool 320 of the corresponding process;

[0033] A2: The fixed clamp inside the first machine tool 320 secures the graphite workpiece and performs processing on the graphite workpiece;

[0034] A3: The gantry robot 310 picks up the graphite workpiece after one process and flips it over;

[0035] A4: The gantry robot 310 transports the graphite workpiece to the second machine tool 330 of the corresponding process;

[0036] A5: The fixed clamp inside the second machine tool 330 secures the graphite workpiece and performs processing on the graphite workpiece;

[0037] A6: The gantry robot 310 picks up the graphite workpiece after secondary processing and places it into the finished product tray.

[0038] In this invention, the gantry robot 310 is a Cartesian coordinate robot manipulator used for automated loading and unloading of CNC machine tools. The first machine tool 320, the second machine tool 330, and the gantry robot 310 are automated devices in industrial applications that are capable of automatic control, reprogrammable, multifunctional, multi-degree-of-freedom, and whose degrees of freedom are spatially perpendicular. This invention combines the gantry robot 310 with a CNC machine tool to achieve automatic gripping, loading, unloading, clamping, shifting and flipping of graphite workpieces, and process sequence transitions for all technological processes.

[0039] Preferably, such as Figure 1As shown, the lathe also includes a processing unit 100 and an execution unit 200. The execution unit 200 controls the movement of the gantry robot 310, the first machine tool 320, the second machine tool 330, automated equipment, and / or other industrial equipment. The execution unit 200 processes and executes instructions sent by the processing unit 100, and controls the movement of the gantry robot 310, sensors, actuators, and other components. The execution unit 200 utilizes a real-time operating system and real-time control technology to ensure high reliability and accuracy in the movement and control of the gantry robot 310. Preferably, the execution unit 200 is communicatively connected to the processing unit 100 for data transmission and exchange. The processing unit 100 can be a PLC (Programmable Logic Controller) for use in industrial automation control systems. It is understood that the processing unit 100 can also employ other hardware capable of implementing various control algorithms through programming to control and manage various equipment in industrial production.

[0040] Preferably, the lathe further includes several image acquisition modules 340. The several image acquisition modules 340 can be set at the positions where clamping, flipping, or switching of processing is required in each process to acquire image data of the graphite workpiece to be processed.

[0041] Preferably, the processing unit 100 acquires the edge contour information of the graphite workpiece based on the acquired image data related to the graphite workpiece to be processed, calculates the edge points of the graphite workpiece, and obtains the center of gravity position of the graphite workpiece by curve fitting of the edge points. Then, based on the correlation between the edge contour information and the center of gravity position of the graphite workpiece and the mass of the graphite workpiece, the clamping point and clamping force of the graphite workpiece are calculated and determined, so as to send control commands to the execution unit 200. More preferably, the processing unit 100 optimizes the clamping point and clamping force of the graphite workpiece based on the number of processes required for the graphite workpiece to be processed and the stress parts of the graphite workpiece corresponding to several processes. An increase in the number of processes will cause the temperature of the graphite workpiece to rise due to multiple processing in a short period of time, which may lead to deformation or cracks during clamping. After the graphite workpiece is processed, the changes in its outer contour, center of gravity, and mass will require corresponding adjustments to the clamping point and clamping force of the graphite workpiece. Therefore, this invention optimizes the clamping points and clamping forces in three stages: before, during, and after the processing of graphite workpieces, to avoid processing damage caused by the special properties of the graphite workpiece material itself.

[0042] To achieve precise image data acquisition, several image acquisition modules 340 employ high-precision industrial cameras paired with light sources to effectively eliminate image distortion and suppress surface reflection on the graphite workpiece. These image acquisition modules 340 are deployed at the clamping stations of the first machine tool 320, the second machine tool 330, and the grasping path nodes of the gantry robot 310, forming a three-dimensional stereoscopic vision monitoring network. During image acquisition, multiple images of the graphite workpiece are acquired through simultaneous multi-camera shooting and integrated into image data. More preferably, the image acquisition modules 340 can acquire image data from the X-axis and Y-axis of the graphite workpiece placement, respectively, and the image data acquired by the image acquisition modules 340 is based on the coordinate system of the gantry robot 310 or the machine tool. In this invention, the image data of the image acquisition modules 340 is acquired using the gantry robot 310 or the machine tool as the coordinate system, which facilitates the processing unit 100 in obtaining the offset between the graphite workpiece and the clamping station from the image data, thereby enabling subsequent edge contour information acquisition.

[0043] Preferably, the processing unit 100 preprocesses the acquired image data to obtain a clear image of the graphite workpiece. The processing unit 100 performs noise removal on the acquired image data based on a filtering method and performs brightness equalization on several images based on histogram equalization. Since image data contains various types of random noise, such as the influence of the equipment itself, the processing environment, and data transmission, the presence of noise is unavoidable and can lead to distortion of details in the image data. Therefore, the processing unit 100 of this invention can use a filtering method to remove random noise. In this invention, the filtering method can be median filtering or mean filtering, which will not be elaborated further. Furthermore, due to differences in parameters and shooting angles among the several image acquisition modules 340, uneven brightness may occur among the acquired images. Therefore, the processing unit 100 adjusts the brightness and contrast among the several images based on the image histogram to equalize the brightness.

[0044] The above image data preprocessing process improves the accuracy of the processing unit 100 in acquiring subsequent edge contour information, ensuring that multiple images in the image data will not have significant differences due to different angles or lighting conditions, thus providing a high-precision data foundation.

[0045] Preferably, the processing unit 100 performs threshold segmentation on the preprocessed image data to obtain the edge contour information of the graphite workpiece. More preferably, the processing unit 100 binarizes the grayscale values ​​in the image data based on the maximum inter-class variance method to obtain the edge contour information of the graphite workpiece. Specifically, the processing unit 100 divides the grayscale values ​​in the image data into two parts according to grayscale levels. These grayscale levels are calculated by the processing unit 100 using variance. Specifically, the processing unit 100 normalizes all pixels in each image, where the grayscale value of each pixel in each image is represented as [1, 2, ..., H], the grayscale level of the image is H, and the number of pixels with a pixel value of h is n. h Therefore, the processing unit 100 can divide all pixels of the image into two parts, C1 and C2, using the gray value G as the boundary. C1 contains pixels with gray values ​​of [1, 2, ..., G], and C2 contains pixels with gray values ​​of [G+1, ..., H]. Preferably, the processing unit 100 uses the quotient of the cumulative average of the pixel gray values ​​up to the gray value G and the probability that the pixel is assigned to C1 as the average gray value assigned to the C1 pixel, and uses this to calculate the average gray value assigned to the C2 pixel. The above calculation formula is as follows:

[0046]

[0047] Where D1 represents the average gray value assigned to pixel C1, D2 represents the average gray value assigned to pixel C2, and D(G) represents the cumulative average of the pixel's gray values ​​up to gray value G. H Let C1 represent the average gray level of the original image, and K(G) represent the probability that a pixel is assigned to C1.

[0048] It is understood that in this invention, the processing unit 100 should divide the image into a background and a workpiece body. Therefore, C1 represents the grayscale value of the background pixel in the image, and C2 represents the grayscale value of the workpiece body pixel in the image. To obtain the optimal threshold for the grayscale value G, the processing unit 100 performs binarized thresholding segmentation of the image based on the maximum inter-class variance method by introducing a variance parameter. The formula for the variance parameter is:

[0049]

[0050] in, Represented as between-class variance, This is expressed as the global variance. Therefore, the inter-class variance... The calculation formula is as follows:

[0051]

[0052] Based on the calculation formulas for the average gray value D1 of pixel C1 and the average gray value D2 of pixel C2, the above formula can be simplified to:

[0053]

[0054] Therefore, the greater the difference between the average gray value D1 and the average gray value D2, the greater the inter-class variance. The larger the value, the better. Since the average gray values ​​D1 and D2 are constants, maximizing the variance parameter is equivalent to maximizing the inter-class variance. This is equivalent to calculating the grayscale value G to maximize the variance parameter. The processing unit 100 calculates the grayscale value in a way that maximizes the variance parameter, and uses this grayscale value as the optimal threshold to perform binarized thresholding segmentation on the original image, thereby obtaining the edge contour information of the graphite workpiece.

[0055] The edge contour information obtained above consists of several contour boundary points on the image of the graphite workpiece. Preferably, the processing unit 100 fits the several boundary points within the edge contour information based on the Hough transform to obtain a continuous edge contour curve of the graphite workpiece after edge detection. It should be noted that the application of the Hough transform in image processing is already widely used, and this invention will not elaborate on it.

[0056] Preferably, the processing unit 100 calculates the centroid coordinates of the region enclosed by the edge contour curve of the graphite workpiece based on the pre-stored density parameters of the graphite workpiece and the continuous edge contour curve of the graphite workpiece to determine the position of the center of gravity of the graphite workpiece. More preferably, the processing unit 100 obtains the thickness distribution of the graphite workpiece at the center of gravity position based on the determined position of the center of gravity and the edge contour curve at the center of gravity position. Preferably, the processing unit 100 filters out regions near the center of gravity position of the graphite workpiece with a thickness greater than a preset threshold, and performs secondary filtering of the region based on the curvature of the edge contour curve to traverse and select several candidate clamping points. The curvature of the edge contour curve can reflect the clamping convenience of the candidate clamping points, making the stress on the stressed part more uniform and reducing local stress concentration. Further, the processing unit 100 filters out regions with an edge contour curvature of less than 5% as candidate clamping points. The processing unit 100 can use several of these candidate clamping points as clamping points of the gantry robot 310, and the processing unit 100 can also perform stress analysis on them to further filter the clamping points. Specifically, the processing unit 100 performs finite element simulation on the graphite workpiece based on its edge contour to simulate the stress on several candidate clamping points. During the finite element simulation, the processing unit 100 inputs at least the material parameters of the graphite workpiece (such as compressive strength, elastic modulus, etc.) and the cutting force parameters that may be encountered during processing. Based on the stress simulation results, the processing unit 100 selects the region where the maximum stress is less than the graphite compressive strength as the final clamping point. Further, based on the stress simulation results, the processing unit 100 selects the region where the maximum stress is less than 80% of the graphite compressive strength as the final clamping point. Therefore, the clamping points selected by the processing unit 100 can ensure that the graphite workpiece can withstand the stress during processing, avoiding workpiece damage during processing.

[0057] In the multi-process conversion stage, the processing unit 100 drives the image acquisition module 340 to acquire images of the graphite workpiece after the previous processing to obtain a new edge contour curve. More preferably, the processing unit 100 compares the edge contour curve after the previous processing with the edge contour curve before processing to calculate the change in the outer contour of the graphite workpiece. The processing unit 100 determines whether the change in the outer contour of the graphite workpiece meets the process standard based on a pre-set target process, and if it does, calculates the current center of gravity offset of the graphite workpiece to adjust the clamping point. More preferably, the processing unit 100 selects the clamping point to avoid the processing area of ​​the previous process of the graphite workpiece as the clamping point for the next process. Since processing the graphite workpiece will cause the temperature of its stressed parts to rise, and graphite has poor heat resistance, excessively high temperatures can easily lead to a decline in its performance. Clamping under such conditions may result in deformation or cracks. Therefore, this invention, after one process, sets the clamping point in a relatively low-temperature area to avoid the area of ​​temperature rise, thus preventing damage to the graphite workpiece caused by clamping in a high-temperature area. Therefore, the present invention can ensure that the clamping point of the gantry robot 310 for each graphite workpiece is located at a position where the graphite workpiece itself has high strength.

[0058] Preferably, the processing unit 100 adjusts the clamping force parameters of the gantry robot 310's gripper based on the contact area between the gripper and the graphite workpiece at several selected clamping points and the mass of the graphite workpiece. The processing unit 100 also sets the control command for the clamping force using a gradient loading method. Since the edge contours and masses of graphite workpieces required in different batches are different, the clamping points corresponding to the graphite workpieces are also different. The main factor affecting the clamping stability of the graphite workpiece is the relationship between its own mass and the clamping force parameters, particularly the contact area between the gripper of the gantry robot 310 and the graphite workpiece, as well as the mass of the graphite workpiece. Preferably, the processing unit 100 obtains the mass of the graphite workpiece based on preset graphite workpiece parameters. Preferably, the processing unit 100 performs a Boolean intersection operation between the model of the gripper of the gantry robot 310 and the edge contour curve of the graphite workpiece to generate a polygonal boundary of the contact area, and obtains the area of ​​this polygonal boundary as the contact area. For irregular contours, the processing unit 100 divides the sample into several sampling points to verify the contact stability between the gripper of the gantry robot 310 and the graphite workpiece, and eliminates clamping points with low contact areas. Since a larger contact area between the gripper of the gantry robot 310 and the graphite workpiece requires a smaller clamping force, and a larger mass of the graphite workpiece requires a larger clamping force, this application adjusts the clamping force parameters of the gripper of the gantry robot 310 based on the relationship between the maximum clamping force for graphite workpieces without deformation and stress concentration, and the contact area and mass, to avoid workpiece damage.

[0059] Preferably, the processing unit 100 generates a control command for gradient loading clamping force based on the adjustment result of the clamping force parameters. The aforementioned gradient loading refers to the execution unit 200 controlling the clamping loading rate to increase and then decrease in an S-shaped curve force change process to avoid the instantaneous acceleration impact of linear loading (linear loading has a constant acceleration value, which easily leads to cracking of brittle materials). Preferably, the processing unit 100 generates a force change process based on the adjustment result of the clamping force parameters, causing the clamping to smoothly start, reach a constant speed, and then gradually end. The time of each stage in this force change process is determined by the thickness of the graphite workpiece. Furthermore, the time of each stage in this force change process can be finely adjusted by the operator using a handwheel.

[0060] More preferably, the processing unit 100 dynamically adjusts the clamping force based on the clamping points of the machine tool and the graphite workpiece and based on the machining stage. During the roughing stage of the graphite workpiece, due to the large cutting force, it is necessary to increase the clamping force to resist the cutting torque and ensure that the graphite workpiece does not experience clamping displacement, thus meeting the positioning accuracy requirements of roughing. Preferably, when the graphite workpiece is in the roughing stage, the processing unit 100 maintains clamping stability by increasing the clamping force at at least three clamping points with relatively large graphite workpiece thickness among the clamping points of the machine tool and the graphite workpiece. During the finishing stage of the graphite workpiece, due to the reduced cutting force of finishing, reducing the clamping force can reduce elastic deformation of the workpiece and improve surface roughness. Preferably, when the graphite workpiece is in the finishing stage, the processing unit 100 avoids elastic deformation of the workpiece by reducing the clamping force at at least two clamping points with relatively small graphite workpiece thickness among the clamping points of the machine tool and the graphite workpiece. The terms "relatively large graphite workpiece thickness" and "relatively small graphite workpiece thickness" refer to comparisons with clamping points at other locations. The reason for dynamically adjusting the clamping force at at least three clamping points during the roughing stage and at least two clamping points during the finishing stage is due to the inherent characteristics of the clamping point selection. Increasing the clamping force at at least three clamping points located on the thicker side of the graphite workpiece ensures that the internal stress change of the graphite workpiece affected by the clamping force is relatively small. The change in clamping force at at least three clamping points ensures that the amount of stress change acts near the center of mass of the graphite workpiece. The more clamping points where the clamping force is adjusted, the smaller the impact of uneven stress on the graphite workpiece. If the clamping force is adjusted at only one or two clamping points, uneven clamping force may occur due to mismatched angles, leading to uneven stress on the graphite workpiece. Reducing the clamping force at at least two clamping points located on the thinner side of the graphite workpiece effectively reduces the deformation impact on the thinner side of the graphite workpiece while preventing stress shift towards that clamping point caused by a reduction in the clamping force at a single clamping point.

[0061] Preferably, after the gripper contacts the graphite workpiece, the processing unit 100 adjusts the duration and magnitude of the clamping force based on the thickness of the graphite workpiece to form a three-stage clamping. This addresses the contradiction that thinner sections of the graphite workpiece will deform if the clamping force is too large, and slip if it is too small. The three-stage clamping refers to the following: In the first clamping force application pre-tightening stage after the gripper contacts the graphite workpiece, the processing unit 100 applies a portion of the target clamping force to initially fit the graphite workpiece against the fixture, releasing localized stress caused by assembly gaps; in the second clamping force application stage, the processing unit 100 reduces the clamping force to allow for stress redistribution within the workpiece; and in the third clamping force application stage, the processing unit 100 slowly applies the clamping force to increase it to the target clamping force, ensuring that stress is evenly distributed throughout the contact area. In this invention, the clamping force applied in the first clamping force application pre-tightening stage can be 50% of the target clamping force; the clamping force applied in the second clamping force application stage can be 30% of the target clamping force, thereby maintaining the workpiece position unchanged and providing stress release space. Under a 30% clamping force, the graphite workpiece has a high stress attenuation, which is sufficient to eliminate the local stress peak in the first clamping force application pre-tightening stage; in the third clamping force application stage, the applied clamping force is gradually increased to the target clamping force to avoid secondary impact.

[0062] It should be noted that the aforementioned dynamic adjustment of clamping force, gradient loading method, and three-stage clamping adjustment do not operate independently, but rather achieve parameter linkage through the coordinated control of the processing unit 100. In other words, the correction of the clamping force can be applied to each of the above stages. Through this multi-dimensional collaborative design, the processing unit 100 achieves full-scenario coverage from basic clamping to special working conditions.

[0063] Therefore, the processing unit 100 of this invention performs correlation analysis between the clamping points and clamping force parameters, and calculates the corresponding required clamping force from a number of determined clamping points. Furthermore, when the processing unit 100 adjusts the clamping points according to the process, it recalculates the appropriate clamping force based on the strength characteristics of the new points. For example, when the clamping point is adjusted to a thicker area, the processing unit 100 will appropriately increase the clamping force to ensure clamping stability. The clamping points and clamping force are interdependent; a suitable clamping point requires a matching appropriate clamping force to achieve the best clamping effect. If the point strength is high, the clamping force can be appropriately increased to ensure stability; if the point strength is relatively low, the clamping force needs to be reduced to avoid damaging the workpiece. This synergistic optimization fully adapts to the characteristics of graphite workpieces, ensuring the stability and safety of the processing.

[0064] The optimization of clamping points and clamping forces by the processing unit 100 creates multi-dimensional technical advantages tailored to the characteristics and processing requirements of graphite workpieces. Its beneficial effects are reflected in multiple aspects, including processing quality, production efficiency, cost control, and the level of intelligence. In terms of processing quality stability, this optimization strategy completely solves the problems of breakage, deformation, and cracking of graphite workpieces caused by improper clamping. Because the processing unit 100 accurately selects high-strength clamping areas through edge contour curve calculations and combines finite element simulation to ensure that the stress at the clamping point is always lower than the material's compressive strength, the local breakage rate of graphite workpieces caused by concentrated clamping forces during processing is reduced. Regarding improved production efficiency, the intelligent clamping solution significantly shortens process changeover time and reduces scrap disposal costs. Especially for graphite workpieces with complex contours, the processing unit 100 avoids multiple trial fittings and adjustments through curve fitting and dynamic calculation of the center of gravity, shortening the preparation time for single-piece processing and reducing the overall production cycle, thus meeting the rapid delivery requirements of high-end graphite products. From the perspective of equipment wear and operational safety, the optimized clamping strategy significantly reduces the wear and maintenance frequency of machine tool fixtures, avoids the impact of traditional rigid clamping on the fixtures, not only protects the graphite workpieces but also reduces the vibration of the machine tool spindle caused by force fluctuations. For operators, the automated clamping process replaces manual adjustment, avoids direct contact with brittle graphite workpieces, and reduces the incidence of work-related injuries caused by workpiece breakage to zero.

[0065] Through the above-mentioned multi-dimensional clamping optimization strategies, this invention addresses the characteristics of graphite materials, such as high brittleness and poor heat resistance, and achieves intelligent control of the entire process from pre-processing prediction and dynamic adjustment during processing to post-processing feedback. This effectively improves the pass rate of graphite workpiece processing, shortens the single-piece processing cycle, and significantly enhances the quality stability and production efficiency of graphite workpiece rotary machining.

[0066] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and do not constitute a limitation on the claims. The scope of protection of this invention is defined by the claims and their equivalents. This specification contains multiple inventive concepts; phrases such as "preferred" or "according to a preferred embodiment" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept. Throughout the text, the feature introduced by "preferred" is only an optional mode and should not be construed as mandatory. Therefore, the applicant reserves the right to abandon or delete relevant preferred features at any time.

Claims

1. A rotary lathe for machining graphite workpieces, comprising a gantry robot (310) for automated loading, a first machine tool (320), and a second machine tool (330), characterized in that, It also includes a processing unit (100), an execution unit (200), and several image acquisition modules (340) located at positions where clamping, flipping, or sequential processing is required in each process to acquire image data of the graphite workpiece to be processed. The processing unit (100) obtains the edge contour information of the graphite workpiece based on the acquired image data related to the graphite workpiece to be processed, calculates the edge points of the graphite workpiece, and obtains the center of gravity position of the graphite workpiece by curve fitting of the edge points. Then, based on the correlation between the edge contour information of the graphite workpiece and the center of gravity position, and based on the mass of the graphite workpiece, it calculates and determines the clamping point and clamping force of the graphite workpiece, so as to send control commands to the execution unit (200).

2. The graphite workpiece rotary machining lathe according to claim 1, characterized in that, The processing unit (100) optimizes the clamping point and clamping force of the graphite workpiece based on the number of processes required for the graphite workpiece to be processed and the stress-bearing parts of the graphite workpiece corresponding to several processes. The processing unit (100) compares the edge contour curve of the graphite workpiece after processing with the edge contour curve before processing to calculate the change in the outer contour of the graphite workpiece. The processing unit (100) determines whether the change in the outer contour of the graphite workpiece meets the process standard based on the preset target process, and calculates the current center of gravity offset of the graphite workpiece to adjust the clamping point if it meets the process standard.

3. The graphite workpiece rotary machining lathe according to claim 2, characterized in that, The processing unit (100) selects the clamping point in a manner that avoids the processing area of ​​the previous process of the graphite workpiece as the clamping point for the next process.

4. The graphite workpiece rotary machining lathe according to claim 3, characterized in that, The processing unit (100) adjusts the clamping force parameters of the gantry robot (310) based on the contact area between the gantry robot (310) and the graphite workpiece at a number of selected clamping points and the mass of the graphite workpiece, and the processing unit (100) sets the control command of the clamping force in a gradient loading manner.

5. The graphite workpiece rotary machining lathe according to claim 4, characterized in that, The processing unit (100) performs a Boolean intersection operation on the model of the gripper of the gantry robot (310) and the edge contour curve of the graphite workpiece to generate a polygonal boundary of the contact area and obtain the area of ​​the polygonal boundary as the contact area.

6. The graphite workpiece rotary machining lathe according to claim 5, characterized in that, The processing unit (100) generates a control command for the gradient loading clamping force based on the adjustment result of the clamping force parameters, wherein, The processing unit (100) generates a force change process based on the adjustment result of the clamping force parameter, which causes the gripper to start smoothly, move at a constant speed, and then end gently. The gradient loading refers to the force change process of the execution unit (200) controlling the gripper speed to increase first and then decrease.

7. The graphite workpiece rotary machining lathe according to claim 6, characterized in that, The processing unit (100) dynamically adjusts the clamping force based on the clamping points of the machine tool and the graphite workpiece and based on the machining stage, wherein, When the graphite workpiece is in the roughing stage, the processing unit (100) maintains clamping stability by increasing the clamping force at at least three of the clamping points between the machine tool and the graphite workpiece where the graphite workpiece has a relatively large thickness. When the graphite workpiece is in the finishing stage, the processing unit (100) avoids elastic deformation of the workpiece by reducing the clamping force based on at least two of the clamping points of the machine tool and the graphite workpiece where the thickness of the graphite workpiece is relatively small.

8. The graphite workpiece rotary machining lathe according to claim 7, characterized in that, After the gripper contacts the graphite workpiece, the processing unit (100) adjusts the duration and magnitude of the clamping force based on the thickness of the graphite workpiece to form a three-segment clamping.

9. The graphite workpiece rotary machining lathe according to claim 8, characterized in that, The processing unit (100) preprocesses the acquired image data to obtain a clear image of the graphite workpiece. The processing unit (100) performs threshold segmentation on the preprocessed image data to obtain the edge contour information of the graphite workpiece. The processing unit (100) fits several boundary points within the edge contour information based on the Hough transform to obtain the continuous edge contour curve of the graphite workpiece after edge detection.

10. The graphite workpiece rotary machining lathe according to claim 9, characterized in that, The processing unit (100) calculates the centroid coordinates of the region enclosed by the edge contour based on the pre-stored graphite workpiece density parameters and the continuous edge contour curve of the graphite workpiece to determine the centroid position of the graphite workpiece. Furthermore, the processing unit (100) obtains the thickness distribution of the graphite workpiece at the centroid position based on the determined centroid position and the edge contour curve at the centroid position. The processing unit (100) filters out regions near the center of gravity of the graphite workpiece whose thickness is greater than a preset threshold, and performs secondary filtering of these regions based on the curvature of the edge contour curve to select several candidate clamping points. The processing unit (100) performs finite element simulation on the graphite workpiece based on the edge contour of the graphite workpiece to simulate the stress on several candidate clamping points, and selects the region with the maximum stress less than the compressive strength of graphite as the final clamping point based on the stress simulation results.

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