A method and apparatus for reworking a silicon carbide green body tube

Abstract

The application discloses a silicon carbide green body pipe repairing method and device, and obtains boundary teaching point coordinates of a converging area to be processed in an axial section of the green body pipe and a converging processing depth, so as to establish a target converging generatrix and form a corresponding relationship between a radial coordinate and an axial coordinate. Further, the target converging generatrix is divided according to an accumulated path length, discrete repairing position data corresponding to each divided position is determined, and a position sequence is formed. During processing, a grinding tool is controlled to move to each discrete repairing position in sequence, and the residence repairing is completed in a rotating state of the silicon carbide green body pipe. By converting the geometric change of the converging contour into the path length distribution along the target converging generatrix, the actual travel difference between adjacent repairing positions in different curvature areas can be reduced, the local material removal amount fluctuation is reduced, and a relatively balanced step-by-step repairing process of the converging arc surface is formed.

Description

Technical Field

[0001] This application relates to the field of CNC machining technology for silicon carbide ceramic green bodies, and in particular to a method and apparatus for trimming silicon carbide green body tubes. Background Technology

[0002] Silicon carbide green tubes are tubular blanks formed from silicon carbide powder but not yet sintered at high temperatures. Before sintering, it is usually necessary to remove excess material in certain areas through trimming, and to contour the inner wall, outer wall, and the converging arc surface formed by the transition from the tube wall to the bottom. Due to the low internal bonding strength and brittle nature of the green tube, large variations in the amount of material removed during processing can easily cause localized stress changes in the blank. Therefore, the machining process of the converging arc surface places high demands on the movement of the grinding tools.

[0003] Existing blank-cutting devices typically control the grinding tool to feed gradually along different directions of motion based on preset machining dimensions. For straight-walled areas, since the machining profile changes little along the feed direction, a fixed feed rate can form a relatively stable machining process. However, the profile direction of the converging area at the bottom of the tube changes continuously. When the same single-axis feed rate is applied to different profile positions, the actual travel distance of the grinding tool on the corresponding machining surface varies. As a result, the material removal status of adjacent trimming positions fluctuates with the change of the converging profile.

[0004] To reduce the aforementioned processing differences, existing technologies typically reduce the overall feed rate, decrease the feed speed, or increase the number of processing passes to moderate the changes between adjacent processing positions. However, the degree of contour change varies across different parts of the convergent arc surface. Uniformly adjusting processing parameters increases processing steps and time, and also fails to reflect the actual processing stroke corresponding to different contour positions. Therefore, in the current silicon carbide green tube trimming process, when the convergent contour changes, the actual processing stroke between adjacent trimming positions is difficult to maintain stability, easily leading to inconsistent processing amounts in different areas. Summary of the Invention

[0005] The main purpose of this application is to solve the technical problem that it is difficult to effectively reduce the difference in plating thickness at different locations in the same contact area in the existing continuous electroplating process for connector contact terminals.

[0006] To achieve this objective, the present application adopts the following technical solution: A method and apparatus for trimming silicon carbide green tubes, comprising: S1, obtain the coordinates of the boundary teaching point and the convergence depth of the convergence region to be processed in the axial section of the green tube; S2, construct the target convergence generatrix based on the boundary teaching point coordinates and convergence processing depth, and determine the relationship between the radial coordinates and axial coordinates of the target convergence generatrix; S3, divide the target convergence bus into multiple equal arc length segments according to the cumulative path length, determine the discrete blanking position data according to the division position of each equal arc length segment, and form a discrete blanking position sequence. S4, according to the discrete trimming position sequence, the grinding tool of the trimming device is controlled to move sequentially to each discrete trimming position along the radial and axial directions, and the dwell trimming is performed at each discrete trimming position in the rotating state of the silicon carbide green tube until the trimming of the area corresponding to the target convergence generatrix is ​​completed.

[0007] This application also discloses a silicon carbide green tube trimming apparatus, including a frame; The frame is provided with an X-axis crossbeam extending in the horizontal direction, and a Z-axis column extending in the vertical direction is suspended from the X-axis crossbeam. A spherical grinding head is provided at one end of the Z-axis column. A rotary mechanism is provided, which is arranged opposite to the ball grinding head along the extension direction of the Z-axis column. The rotary mechanism includes a drive mechanism, a reduction mechanism and a chuck. The drive mechanism drives the chuck through the reduction mechanism, and the silicon carbide green tube is vertically clamped in the chuck.

[0008] Compared with the prior art, this application has the following beneficial effects: This application obtains the actual boundary position and convergence depth of the convergence region to be processed, so that the constructed target convergence generatrix corresponds to the convergence profile of the silicon carbide green tube to be processed. On this basis, the radial and axial changes of different positions of the generatrix are unified into the same curve path for characterization, so that the determination of the processing position no longer depends solely on the fixed feed amount in a certain motion direction.

[0009] The segments are divided according to the cumulative path length of the target convergence generatrix, so that each segment position can change accordingly with the curvature of the convergence profile. The adjacent trimming positions are jointly defined by the actual curve path of the regions with large curvature changes and regions with small curvature changes, thereby reducing the difference in actual movement stroke of adjacent positions caused by the change of the convergence profile. The resulting discrete trimming position sequence is further transformed into the radial and axial movement positions of the grinding tool. The grinding tool arrives at each discrete trimming position in sequence and completes the corresponding position dwell trimming while the green tube is rotating, so that the position distribution determined along the convergence generatrix forms a continuous correspondence with the actual circumferential material trimming process.

[0010] In summary, this application can reduce the fluctuations in machining stroke and material removal amount caused by contour changes in different parts of the converging arc surface, so that the blanking process in the converging region has a more balanced step-by-step machining state. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0013] Figure 1 This is a schematic diagram illustrating the overall steps of the silicon carbide green tube trimming method of this application. Figure 2 This is a flowchart of a silicon carbide green tube trimming method according to one embodiment of this application; Figure 3 This is a control relationship block diagram of a silicon carbide green tube trimming device according to one embodiment of this application; Figure 4 This is a comparative schematic diagram of the step-by-step trajectory of the convergent arc surface of a silicon carbide green tube according to one embodiment of this application; Figure 5 This is a schematic diagram of the layered reciprocating repair trajectory of a straight section of a silicon carbide green billet tube according to one embodiment of this application. Figure 6 This is a cross-sectional structural schematic diagram of a silicon carbide green tube trimming apparatus according to one embodiment of this application.

[0014] Reference numerals in the attached drawings: 1. Frame; 2. X-axis crossbeam; 3. Z-axis column; 4. Spherical grinding head; 5. Rotary mechanism; 51. Drive mechanism; 52. Reduction mechanism; 53. Chuck; 6. Silicon carbide green tube. Detailed Implementation

[0015] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.

[0017] The technical solution of this application will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] refer to Figures 1 to 6 This application provides a method for trimming silicon carbide green tubes, applied to a silicon carbide green tube trimming apparatus, the trimming method comprising: S1: Obtain the coordinates of the boundary teaching point and the convergence depth of the convergence region to be processed within the axial section of the green tube; In step S1, after the silicon carbide green tube enters the converging region trimming state, teaching data describing the spatial range of this converging region is acquired. The operator controls the grinding tool to move radially and axially through the manual or automatic operation mode of the trimming device, gradually bringing the grinding tool closer to the converging region where the green tube transitions from the straight wall to the bottom. When the grinding tool moves to one side boundary position of the converging region within the axial section of the green tube, the radial and axial coordinates corresponding to that position are read and recorded as the first boundary teaching point.

[0019] The grinding tool is controlled to exit its current position and move to the other boundary of the convergence region. When the grinding tool reaches the other boundary position, the corresponding radial and axial coordinates are read again and recorded as the second boundary teaching point. In this embodiment, the convergence profile is an arc-shaped profile symmetrical about the axis of the green tube. Therefore, the two boundary teaching points are located at the same axial height, which can be represented as (X1, Z0) and (X2, Z0) respectively. The above teaching process obtains the two end positions that can limit the radial span of the convergence region, so that the workpiece position in the actual clamping state directly participates in the construction of the convergence profile.

[0020] After completing the boundary teaching, the processing depth parameters corresponding to the current convergence region are set. In this embodiment, the depth of cut per pass and the total number of layers are first determined based on the bottom dimensions of the product to be processed. The product of the total number of layers and the depth of cut per pass is then determined as the convergence processing depth H, which represents the total processing distance extending from the axial positions of the two boundary teaching points towards the bottom of the tube. For example, if the total number of layers is set to N and the depth of cut per pass is set to d, then the convergence processing depth in this embodiment satisfies H = N * d. Simultaneously, the feed rate and cutting time per step required for processing the current convergence region are entered, so that the boundary teaching point coordinates and the convergence processing depth constitute geometric data, and the feed rate, number of steps, and cutting time constitute the processing execution parameters. After completing the above data reading and parameter setting, the first boundary teaching point, the second boundary teaching point, and the convergence processing depth are associated with the current convergence region processing task of the silicon carbide green tube.

[0021] S2: Construct the target convergence generatrix based on the boundary teaching point coordinates and convergence processing depth, and determine the relationship between the radial and axial coordinates of the target convergence generatrix; In step S2, after obtaining the first boundary teaching point, the second boundary teaching point, and the convergence processing depth, the radial range of the convergence region is defined by the two boundary teaching points, and the axial range extending towards the bottom of the tube is defined by the convergence processing depth, thus establishing the target contour of the convergence region to be processed within the axial section of the green tube. In this embodiment, an elliptic curve is used to describe the target contour. The midpoint between the radial coordinates X1 of the first boundary teaching point and X2 of the second boundary teaching point is calculated, and the average of the two radial coordinates is taken as the radial coordinate C of the convergence center. x This process determines the center position of the convergence profile relative to the two boundary positions. Then, half the radial distance between the two boundary teaching points is calculated to obtain the semi-axis length *a* of the ellipse in the radial direction. Since the two boundary teaching points have the same axial coordinate Z0, this axial coordinate is used as the starting height of the convergence profile. Then, the convergence processing depth *H* obtained in step S1 is taken along the convergence direction to determine the axial coordinate Z0-H of the arc bottom position. The radial coordinate of the arc bottom corresponds to the radial coordinate of the convergence center. The convergence processing depth refers to the target processing depth extending from the axial position of the boundary teaching point towards the bottom of the tube; in this embodiment, it corresponds to the axial semi-axis dimension of the elliptical profile. The target convergence generatrix refers to the target profile curve corresponding to the convergence arc surface to be processed within the axial section of the green tube. When the green tube rotates around its own axis, this target convergence generatrix forms the corresponding convergence arc surface.

[0022] Two boundary teaching points determine the radial expansion range of the elliptical profile, and the convergence machining depth determines the axial extension range of the elliptical profile. These three factors together determine the convergence curve corresponding to the current workpiece. In specific implementation, the elliptical profile satisfying the above geometric relationship is used as the target convergence generatrix. A quarter-elliptical arc extending continuously from the corresponding boundary position to the arc base is obtained based on the actual machining side. The starting position of the target convergence generatrix corresponds to the current boundary teaching point, and the ending position corresponds to the arc base position. After the target convergence generatrix is ​​established, each position on the generatrix can be represented by radial coordinate X and axial coordinate Z. The changes in radial and axial coordinates are constrained by the same elliptical geometric relationship. For any given generatrix position, a set of corresponding radial and axial coordinates can be obtained. This coordinate relationship and the geometric parameters of the current generatrix are saved as the trajectory data of the current machining task, thereby transforming the finite boundary data obtained in S1 into a continuous target convergence profile.

[0023] S3: Divide the target convergence bus into multiple equal arc length segments according to the cumulative path length, and determine the discrete blanking position data according to the division position of each equal arc length segment to form a discrete blanking position sequence. In step S3, after the target convergence generatrix is ​​established, the cumulative path length of the target convergence generatrix from the boundary position to the arc bottom position is obtained. Specifically, the elliptical target convergence generatrix is ​​converted into a form represented by curve parameters θ, and the parameter interval corresponding to the boundary position to the arc bottom position is set to 0 to π / 2. Sufficiently dense computation nodes are set within the above parameter interval according to the numerical arc length of the curve; for example, the parameter interval is evenly subdivided into 2000 small intervals, so that each parameter value corresponds to a computation node on the target convergence generatrix. Each parameter value is substituted into the target convergence generatrix to obtain the radial and axial coordinates of the corresponding computation node.

[0024] After obtaining the coordinates of each calculation node, the straight-line distance between adjacent nodes is calculated sequentially starting from the curve's starting point. The distance between one node and the next node is determined by the radial and axial coordinate differences between the two nodes. These straight-line distances are then accumulated sequentially to form a cumulative path length array from the starting node to each calculation node. The cumulative value at the end of the array is the total arc length L of the target convergence generatrix from the boundary position to the arc base position. The number of steps N set in step S1 is called to divide the total arc length L into N segments of equal length. The target cumulative path length corresponding to the k-th segment position is Lk / N. Since the target cumulative path length is usually located between the cumulative lengths of two calculation nodes, the interval containing the target value is searched in the cumulative path length array. Then, linear interpolation is performed based on the cumulative path lengths at both ends of the interval and the corresponding curve parameters to obtain the curve parameter value corresponding to the target cumulative path length.

[0025] Substituting the obtained parameters back into the target convergence generatrix established in step S2, the radial and axial coordinates corresponding to the segmentation position can be obtained, and this set of coordinates can be recorded as a discrete trimming position data. By processing the cumulative path length from the first target to the Nth target in the same way, all discrete trimming position data arranged sequentially from the boundary of the convergence region to the bottom of the arc can be obtained, and a discrete trimming position sequence can be generated according to their order of appearance on the target convergence generatrix.

[0026] S4: According to the discrete blanking position sequence, control the grinding tool of the blanking device to move sequentially to each discrete blanking position along the radial and axial directions, and perform dwelling and dressing at each discrete blanking position while the silicon carbide green tube is rotating, until the blanking of the area corresponding to the target convergence generatrix is ​​completed. In step S4, after completing the calculation of the discrete trimming position sequence, the position sequence is used as the motion target data in the actual trimming process in the convergence region. At the start of processing, the rotational motion of the grinding tool and the slewing motion of the silicon carbide green tube are initiated, and the first set of radial and axial coordinates are read from the beginning of the discrete trimming position sequence. The trimming device generates the corresponding radial and axial motion amounts based on the coordinate difference between the current position and the target position of the grinding tool, and then drives the grinding tool to move synchronously along the radial and axial directions towards the first discrete trimming position.

[0027] In this embodiment, adjacent discrete trimming positions are moved in a linked linear motion, meaning that radial and axial movements participate in a single position transition, allowing the grinding tool to move directly from the previous position to the next. After reaching the current discrete trimming position, the grinding tool enters a dwelling and trimming stage. At this point, the radial and axial positions no longer change, and the grinding tool itself performs grinding rotation, causing the silicon carbide green tube to rotate around its own axis. Therefore, the current position of the grinding tool within the axial section of the green tube forms a corresponding circumferential trimming area as the green tube rotates. The dwell time is the pre-set cutting time in step S1, within which the circumferential material trimming corresponding to the current discrete position is completed. After the current dwell time ends, the next set of radial and axial coordinates is read from the discrete trimming position sequence, causing the grinding tool to move linkedly from the current discrete trimming position to the next discrete trimming position and re-enter the dwelling and trimming state. Dwell dressing refers to the grinding tool reaching a discrete dressing position and then temporarily ceasing to feed to the next position. It continues to cut for a preset time at that position while the silicon carbide green tube is in a rotating state, thereby completing the dressing of the corresponding circumferential area at that position before moving to the next discrete dressing position.

[0028] In the discrete blank-cutting position sequence, each set of position data undergoes position calling, linked movement, and dwelling and finishing processes in sequence, causing the grinding tool to gradually advance from the boundary position of the convergence region towards the bottom of the arc. When the last position in the sequence completes the dwelling and finishing, the grinding tool reaches the bottom of the arc of the target convergence generatrix, thus completing the blank-cutting of the entire region corresponding to the target convergence generatrix. Since each adjacent discrete position corresponds to the equal arc length segment obtained in step S3, the actual machining trajectory consists of the linked movement between multiple adjacent positions, and as the number of discrete positions increases, it forms a segmented approximation of the target convergence generatrix.

[0029] In summary, this application acquires the boundary teaching point coordinates and convergence depth of the convergence region at the start of the trimming process, enabling the actual position and dimensions of the region to be processed to be converted into calculable geometric data. Based on this geometric data, a target convergence generatrix is ​​constructed, transforming the spatial contour of the convergence arc surface into a continuous relationship between radial and axial coordinates. Then, based on the cumulative path length of the target convergence generatrix, equal arc lengths are divided, converting the continuous curve into sequentially arranged discrete trimming position data. This transforms the determination of adjacent trimming positions from a single axial feed amount to the actual path length along the target convergence generatrix. During processing, the grinding tool moves sequentially to each discrete trimming position and performs dwell trimming while the silicon carbide green tube is rotating, until the entire target convergence region is completed. The curvature changes at different positions of the convergence contour can be reflected in the spatial distribution of the discrete trimming positions, reducing the significant differences in actual processing strokes between adjacent trimming positions when using a fixed single-axis feed. This reduces fluctuations in material removal in different regions, making the step-by-step trimming process of the convergence arc surface more balanced.

[0030] It is worth noting that the "processing convergence region" referred to in this application refers to the area of ​​the silicon carbide green tube that gradually transitions from a straight wall to the bottom, forming a curved profile, and needs to be trimmed; the axial section of the green tube refers to the longitudinal section formed through the axis of the silicon carbide green tube, in which both the radial and axial movements of the grinding tool can be represented. The boundary teaching point refers to the position coordinates recorded by the trimming device after the operator controls the grinding tool to move to the characteristic boundary position of the processing convergence region.

[0031] In one embodiment, before teaching and trajectory calculation in the convergence region, the clamping and process coordinate establishment of the silicon carbide green tube are completed first. The silicon carbide green tube to be processed is vertically clamped on the rotary mechanism, so that the axis of the green tube corresponds to the rotation axis of the rotary mechanism, so that the surface to be processed can rotate around the predetermined axis when the green tube rotates. The grinding tool is moved to the starting position set by the current processing task through the manual jogging function of the blank dressing device. At this position, the radial and axial positions of the grinding tool are read, and the current positions in both directions are cleared to zero, forming the process coordinate origin corresponding to the current workpiece. A two-dimensional process coordinate system is established from this process coordinate origin. One coordinate direction reflects the radial position of the grinding tool relative to the axis of the green tube, and the other coordinate direction reflects the processing depth of the grinding tool along the axis of the green tube. During the current workpiece processing, whether it is the position of the boundary teaching point, the target convergence generatrix, or the discrete blank dressing positions obtained by calculation, they are all represented by the same coordinate origin and the same coordinate direction. For example, after the grinding tool is zeroed at the initial position, when it moves a certain distance radially and then a certain distance axially downward, the two-dimensional coordinates of that position relative to the process origin can be directly obtained, instead of reusing the machine coordinates. In this way, the aforementioned teaching coordinates, trajectory calculation coordinates, and actual motion coordinates have a unified data meaning, thus enabling them to be directly and continuously used in the same machining task.

[0032] In one embodiment, the boundary teaching points obtained in step S1 include a first boundary teaching point and a second boundary teaching point located on both sides of the convergence region to be processed. The two teaching points are at the same axial height, and therefore can be represented as (X1, Z0) and (X2, Z0) respectively. X1 and X2 are directly derived from the same boundary teaching process, and Z0 represents the common axial coordinate of the two boundary teaching points. After obtaining the above coordinates, the midpoint of the two boundary teaching points in the radial direction is calculated, and this position is defined as the convergence center, with the following radial coordinates: ; in, The radial coordinates of the convergence center are calculated to reflect the midpoint of the two boundary positions in the radial direction. For example, as an illustrative example, when the radial coordinates of the first boundary teaching point are 100 mm and the radial coordinates of the second boundary teaching point are 200 mm, the radial coordinates of the convergence center are 150 mm.

[0033] The radial half-axis length of the target convergence generatrix is ​​further determined based on the radial distance between the two boundary teaching points, and its expression is as follows: ; Where 'a' represents the radial distance from the convergence center to any boundary teaching point. Taking the above example, if the two boundary points are 100 mm apart, then the radial half-axis length is 50 mm. The convergence processing depth H has already been obtained in step S1; therefore, the axial position Z0 where the two boundary points are located, together with the convergence processing depth H, defines the axial extension range of the target convergence generatrix. In this embodiment, an elliptical contour is used to describe the convergence region, and its expression is: ； Where X and Z represent the radial and axial coordinates of the position to be determined on the target convergence generatrix, respectively. From the above relationship, it can be seen that when the position is at the boundary end, the radial coordinate relative to... The offset is close to 'a', and the axial coordinate is close to 'a'. As the position gradually moves towards the bottom of the arc, the radial coordinates gradually approach... The axial coordinates gradually move towards H changes. The expression transforms the boundary teaching points and convergence processing depth obtained in step S1 into a continuous geometric generatrix, instead of relying on manually giving the coordinates of the entire arc surface point by point.

[0034] In one embodiment, step S2 has already determined the geometry of the target convergence generatrix using the general equation of an ellipse. However, in order to calculate the cumulative path length along different positions of the generatrix, it is necessary to further transform the geometric generatrix into a parametric form that can continuously obtain the coordinates of each position. The target convergence generatrix is ​​represented by the parameter θ as follows: ; Where θ is the curve parameter of the target convergence generatrix. In this embodiment, the quarter-elliptical arc extending from the boundary position to the arc base is taken as 0≤θ≤π / 2. The positive or negative sign in the formula is determined according to the radial side being processed. After selecting the current processing side, the corresponding single branch is used in one arc segment calculation process. and The radial and axial coordinates of the target convergence generatrix position are given respectively under the same curve parameters.

[0035] In specific calculations, the parameter interval is divided into multiple consecutive smaller intervals. For example, the range from 0 to π / 2 can be subdivided into 2000 segments, thus obtaining the parameter values ​​θ0, θ2, θ3, θ4, θ5, θ6, θ7, θ8, θ9, θ1, θ2, θ1, θ2, θ3, θ4, θ5, θ6, θ7, θ8, θ 1、 θ2……θ n By substituting each parameter value into the above parameter expression, the corresponding computation node can be obtained. =( , The straight-line distance between two adjacent computation nodes is: ; in, , Let be the coordinates of the i-th computation node. , Let be the coordinates of the (i+1)th computation node. This distance is actually the chord length between two adjacent discrete nodes. Since the parameter interval is divided sufficiently, the chord length corresponding to each small segment can be used as a numerical approximation of the length of that small segment of the curve. Then, starting from the beginning of the target convergence generatrix, each chord length is sequentially accumulated. For example, the cumulative path length from the first node to the third node can be obtained by adding the distances of the first two adjacent nodes. This process continues until the bottom of the arc is reached, thus obtaining the total arc length L from the boundary to the bottom of the arc. This also establishes the corresponding data between each calculated node and its cumulative path length. It is worth noting that the above embodiment describes how the target convergence generatrix is ​​geometrically determined. This embodiment further transforms the same generatrix into a series of computable nodes and establishes the data relationship between parameter positions, coordinate positions, and cumulative path lengths, providing a numerical basis for equal arc length partitioning.

[0036] In one embodiment, the current convergence region is planned to be divided into N trimming sections. The total arc length L is divided into N equal parts, and the target cumulative path length corresponding to the k-th segment position can be determined as L*k / N. For example, as an illustrative example, when the total arc length is 120 mm and the preset number of steps is 12, each segment position corresponds to a target cumulative path length of 10 mm, 20 mm, 30 mm up to 120 mm. The calculation nodes established in the above embodiment are usually very dense, but a certain target cumulative path length may still fall between two adjacent calculation nodes. Therefore, the adjacent node interval containing the target value is searched in the cumulative path length data, and then interpolation is performed according to the cumulative path lengths at both ends of the interval and the curve parameters to obtain the curve parameters corresponding to the target cumulative path length. After obtaining the curve parameters, they are substituted back into the parameter form of the target convergence generatrix to obtain the radial and axial coordinates corresponding to the position. This set of coordinates constitutes a discrete trimming position data. The above processing is repeated for all target cumulative path lengths to form a discrete trimming position sequence arranged sequentially from the boundary of the convergence region to the bottom of the arc. The discrete blanking position is first determined by the actual cumulative length of the target generatrix, and then the coordinates of the corresponding position in the two-dimensional machining plane are calculated. This involves dividing the total arc length equally according to the total number of layers, finding the interval where the target value is located in the cumulative arc length array and performing linear interpolation, and then obtaining the coordinates of the corresponding step point.

[0037] In another embodiment, reference Figure 4 , Figure 4The left image shows a schematic diagram of the step-by-step trajectory divided equally by arc length, and the right image shows a schematic diagram of the comparison trajectory divided equally by axial depth. Taking the elliptical target convergence generatrix formed by the convergence region to be processed within the axial section of the green tube as an example, the first boundary teaching point and the second boundary teaching point are located at radial coordinates of -20 mm and 20 mm, respectively, and the axial coordinates of both boundary teaching points are 0 mm. The radial coordinate of the convergence center is determined to be 0 mm, and the radial half-axis length of the target convergence generatrix is ​​20 mm. The convergence processing depth is set to 30 mm, then the radial coordinate corresponding to the arc bottom position is 0 mm, and the axial coordinate is -30 mm. Since the target convergence generatrix is ​​symmetrical about the convergence center, this embodiment uses... Figure 4 The quarter-elliptical arc extending from the right boundary position (20, 0) to the arc bottom position (0, -30) is used as the current processing side for explanation. Based on the parameter form of the target convergence generatrix, multiple parameter values ​​are sequentially taken within the curve parameter range of 0 to π / 2. For example, this parameter range is subdivided into 2000 calculation intervals, and the radial and axial coordinates corresponding to each parameter value are calculated respectively, thus obtaining the calculation nodes continuously arranged along the target convergence generatrix. Then, the straight-line distance between adjacent calculation nodes is calculated sequentially, and accumulated segment by segment starting from the right boundary position to obtain the cumulative path length of each calculation node and the total arc length L between the right boundary position and the arc bottom position.

[0038] exist Figure 4 In the equal arc length step-by-step method shown on the left, taking the division of the target convergence generatrix into three trimming sections as an example, one-third, two-thirds, and the total arc length L are respectively determined as the target cumulative path lengths corresponding to the three segmentation positions. The adjacent calculation node intervals of each target cumulative path length are found in the cumulative path length data. Then, interpolation is performed based on the cumulative path length and curve parameters corresponding to that interval to obtain the curve parameters corresponding to the three segmentation positions. The corresponding radial and axial coordinates are then calculated based on the obtained curve parameters, thus obtaining... Figure 4 The left side shows the corresponding discrete trimming positions. The path lengths of the three adjacent segments along the target convergence generatrix are approximately 13.3 mm, 13.1 mm, and 12.8 mm, respectively. The actual travel distances of each segment are within a similar range, thus forming a sequence of discrete trimming positions that gradually converge from the boundary position to the bottom of the arc. During the actual trimming process, the grinding tool sequentially calls the above discrete trimming position data, moving gradually from the right boundary position to the corresponding position, and performing dwell trimming at each discrete trimming position.

[0039] Under the same elliptical profile and a convergence depth of 30 mm, Figure 4The right side shows a comparison process divided equally by axial depth. The 30 mm convergence depth is divided into three 10 mm depth intervals. The axial coordinates of the three intervals are -10 mm, -20 mm, and -30 mm, respectively. The radial coordinates corresponding to each axial coordinate are then determined based on the target convergence generatrix. Since the elliptical generatrix gradually flattens as it extends from the boundary towards the bottom of the arc, the same 10 mm axial change does not correspond to the same radial change. Therefore, after mapping the three depth intervals to the target convergence generatrix, the corresponding actual path lengths are approximately 10.1 mm, 10.8 mm, and 18.0 mm, respectively. Particularly in the section moving from the axial coordinate -20 mm to the bottom of the arc (-30 mm), although the axial change is still 10 mm, because this area is close to the bottom of the elliptical arc, the grinding tool needs to generate a larger radial displacement, making the actual travel distance in this section significantly greater than the previous two sections. If this step-by-step method is directly used for blank trimming, the actual transfer stroke between adjacent trimming positions will vary significantly with the change in the convergence profile.

[0040] Therefore, under the same target convergence bus and the same number of steps, Figure 4 The step-by-step method on the left uses the cumulative path length of the target convergence generatrix as the basis for segmentation, so that the segmentation position can adjust the radial and axial coordinates according to the curvature of the elliptical contour. Figure 4 The comparison method on the right uses a fixed axial depth as the segmentation basis, which significantly increases the actual curve path length near the bottom of the arc. This embodiment actually uses... Figure 4 The equal arc length step-by-step method shown on the left and the equal depth division method shown on the right serve as a comparative illustration under the same geometric conditions, thereby specifically demonstrating that the discrete blanking position described in this application is determined based on the actual cumulative path length of the target convergence generatrix.

[0041] In one embodiment, the discrete trimming position sequence is used as the position command data for the grinding tool to progressively execute the convergence region machining. After machining begins, the current position data in the discrete trimming position sequence is read, including the target radial coordinate and the target axial coordinate. The trimming device generates radial motion based on the difference between the target radial coordinate and the current radial position, and axial motion based on the difference between the target axial coordinate and the current axial position. The radial feed mechanism and the axial feed mechanism jointly drive the grinding tool to move towards the current discrete trimming position. In one embodiment, two-way linkage linear interpolation is used between two adjacent discrete trimming positions, allowing the grinding tool to directly transition from the previous position to the current target position. After the radial feed mechanism reaches the target radial coordinate and the axial feed mechanism reaches the target axial coordinate, the current position transition process ends, and the cutting timing stage begins. At this time, the grinding tool rotates, and the silicon carbide green tube rotates around its own axis. The grinding tool acts on the circumferential surface that passes through the position as the workpiece rotates at the current two-dimensional position. Once the cutting time reaches the preset time, the dwell cutting corresponding to the current discrete trimming position ends, and the next set of radial and axial coordinates is read from the discrete trimming position sequence to enter the next position transformation. This process is repeated for each discrete trimming position until the trimming is completed at the arc bottom position at the end of the sequence.

[0042] In one embodiment, a separate layered trimming process is set up for the straight sections of the silicon carbide green tube. Before starting the machining of the straight section, the axial machining termination position, axial layered feed amount, radial machining termination position, radial inter-row feed amount, and the cutting time corresponding to each layer position are input according to the machining range of the current straight section. During machining, the grinding tool is first in the current radial machining row. Under the condition that the radial position remains unchanged, it moves axially by one layered feed amount. After reaching the corresponding depth, it performs dwell cutting. After the cutting time reaches the set value, it moves axially again by one layered feed amount, thereby forming a layer-by-layer trimming within the same machining row. As an illustrative example, if the current axial machining area needs to be divided into several layers, the grinding tool continues to enter the next layer after completing the dwell cutting of each layer, until the axial machining termination position is reached. After completing all axial layers of the current machining row, the grinding tool returns to the axial starting position corresponding to that row, and then moves radially by one inter-row feed amount, thereby entering the adjacent machining row, and repeating the axial layer-by-layer trimming. The process continues until the radial position of the grinding tool reaches the set radial machining termination position, thereby covering the machining area corresponding to the current straight pipe section.

[0043] In another embodiment, reference Figure 5 , Figure 5The diagram shows the reciprocating progressive cutting trajectory for the straight pipe section, with the horizontal axis representing the X-axis radial position of the grinding tool and the vertical axis representing the Z-axis depth position. The current machining start position of the silicon carbide green pipe is set to X=0 mm and Z=0 mm, the axial machining end position is set to Z=-20 mm, the axial layer feed is set to 5 mm, the radial machining end position is set to X=30 mm, and the radial inter-row feed is set to 10 mm. Simultaneously, the cutting time at each layer position and the Z-axis return speed are set according to the state of the green pipe material. At the start of processing, the grinding tool is positioned at X=0 mm in the first processing column. It first moves from Z=0 mm to Z=-5 mm, temporarily stopping axial feed upon reaching this layering position. The silicon carbide green tube continues to rotate around its own axis, and the grinding tool performs a preset circumferential dressing at this position. After completing the cutting at this position, the grinding tool continues to move along the Z direction to Z=-10 mm, performing dwell cutting in the same manner. It then moves sequentially to Z=-15 mm and Z=-20 mm, thus completing the layer-by-layer dressing of the first processing column throughout the entire axial processing range. After completing the first processing column, the grinding tool does not move directly radially but returns from Z=-20 mm to Z=0 mm along the dotted line trajectory shown in the figure. This return stroke uses an independently set return speed, distinguishing the return process from the actual cutting feed process. After returning to Z=0 mm, the grinding tool moves again from X=0 mm to X=10 mm in the direction indicated by the arrow in the figure, thus entering the second processing column. After entering the second machining column, layered feed and dwell cutting are sequentially performed between Z=0 mm and Z=-20 mm, then returning to Z=0 mm and moving to X=20 mm; the same process continues until the end machining column corresponding to X=30 mm. In summary, the entire straight pipe section machining area is divided into multiple machining columns arranged radially, and each machining column is further divided into multiple layered finishing positions arranged axially. The grinding tool completes the finishing of the entire straight pipe section area using a cyclical motion of axial layer-by-layer machining, axial return, and radial column switching. It is worth noting that... Figure 5 The values ​​in the figure mainly represent an example of the control process in this embodiment. The actual axial termination position, layer feed amount, radial termination position and inter-row feed amount can be set according to the trimming range of silicon carbide green tubes of different specifications.

[0044] In one embodiment, the operating status of the trimming device is periodically read during the movement of the grinding tool from one discrete trimming position to another. Within each monitoring cycle, the motion control bus status, radial feed mechanism servo status, axial feed mechanism servo status, grinding tool drive status, and the duration of the current motion process are acquired and compared with the normal operating conditions of the current machining task. When the motion control bus returns to an abnormal state, the current state is identified as a bus abnormality; when the radial feed mechanism, axial feed mechanism, or grinding tool drive is no longer in a permissible servo state, the current state is identified as a servo abnormality; when the grinding tool is in a position transition process and the motion duration exceeds a set threshold without reaching the current target position, the current state is identified as a motion timeout. Upon detection of any of these abnormalities, the radial and axial feeds are stopped, and the grinding tool drive and the rotation of the silicon carbide green tube are also stopped. The target position corresponding to the occurrence of the abnormality, the current machining status, and the time already executed in this dwell-cutting process are recorded. The aforementioned recorded data serves as the basis for recovery after the anomaly is resolved, enabling the system to distinguish whether the grinding tool is in a position change process or a dwelling and dressing process when the anomaly occurs.

[0045] In one embodiment, after the abnormal state is investigated and resolved, the entire convergence region trimming process is not directly restarted. Instead, the current operating status of the grinding tool and the rotary mechanism is first checked. When the grinding tool and the rotary mechanism are in an operating state that allows for resumption of processing, the processing status and target position data saved when the abnormality occurred are read. If the abnormality occurs during the dwell trimming process, the remaining cutting time is obtained by subtracting the accumulated cutting time before the abnormality occurred from the original cutting time set at the current discrete trimming position, and the remaining cutting time is continued to be executed at the current discrete trimming position. For example, as an illustrative example, if the cutting time is set to 30 seconds at a certain position, and an abnormality occurs after 12 seconds, the process continues to execute for 18 seconds after recovery, instead of re-executing the full 30 seconds. If the abnormality occurs during the movement of the grinding tool from the previous discrete position to the target position, the target position coordinates saved before the abnormality occurred are read, and the current position when the grinding tool stopped is obtained. The current position is used as the new starting point for movement, and the grinding tool is re-controlled to move towards the original target position. After reaching the target position, the corresponding dwell trimming is then performed. The dwell phase recovers with the remaining cutting time, and the position transition phase recovers with the original target position. In both states, the data saved before the exception is called to continue cutting.

[0046] refer to Figure 6This application also discloses a silicon carbide green tube trimming device, including a frame 1. The frame 1 adopts a vertical frame structure and forms a processing area for placing the silicon carbide green tube 6 and for the movement of grinding tools. An X-axis beam 2 extending horizontally is provided on the frame 1, forming a bearing base for the radial movement of the grinding tools. A feed part that can move along its length is provided on the X-axis beam 2. A Z-axis column 3 extending vertically is suspended from the X-axis beam 2. The Z-axis column 3 changes its radial position with the movement of the X-axis direction. At the same time, the Z-axis column 3 itself provides axial movement in the vertical direction, so that the grinding tools mounted at the end of the Z-axis column 3 can change their radial and axial positions relative to the silicon carbide green tube 6 respectively. In this embodiment, the grinding tool is specifically a spherical grinding head 4. The spherical grinding head 4 is set at one end of the Z-axis column 3 facing the silicon carbide green tube 6. The spherical grinding head 4 moves axially with the Z-axis column 3 and changes position radially with the feed motion corresponding to the X-axis beam 2, thereby forming a two-dimensional motion range within the axial section of the green tube.

[0047] The frame 1 is also equipped with a rotary mechanism 5, which is arranged opposite to the ball mill head 4 along the extension direction of the Z-axis column 3, so that the clamped silicon carbide green tube 6 is within the processing range of the ball mill head 4. The rotary mechanism 5 includes a drive mechanism 51, a reduction mechanism 52, and a chuck 53. In this embodiment, the drive mechanism 51 can be a three-phase motor, the reduction mechanism 52 is a rotary reducer connected to the output end of the three-phase motor, and the chuck 53 is a three-jaw chuck 53. The rotational motion output by the three-phase motor is reduced by the rotary reducer and then transmitted to the three-jaw chuck 53, which clamps the silicon carbide green tube 6, causing the green tube to rotate around its own axis. The silicon carbide green tube 6 is clamped in a vertical position, with its axis set along the extension direction of the Z-axis column 3, and the ball mill head 4 enters the corresponding processing position from the opening side of the green tube. During processing, the rotary mechanism 5 drives the silicon carbide green tube 6 to rotate around its own axis. The feed motion corresponding to the X-axis beam 2 changes the radial distance of the spherical grinding head 4 relative to the axis of the green tube, and the feed motion corresponding to the Z-axis column 3 changes the processing position of the spherical grinding head 4 along the axis of the green tube. This allows the spherical grinding head 4 to move along a predetermined trajectory in the axial section while the green tube rotates. For straight tube sections, the spherical grinding head 4 can move axially layer by layer at a set radial position; for the tube bottom convergence region, the spherical grinding head 4 can generate a combination of radial and axial movements according to the discrete trimming position sequence, thereby enabling the above trimming method to be executed through the above mechanical structure.

[0048] In one embodiment, reference Figure 3The control unit of the silicon carbide green tube trimming device includes an industrial computer, a motion control card, a radial feed mechanism, an axial feed mechanism, a grinding tool drive mechanism, and a rotary mechanism. The industrial computer performs parameter setting, teaching data acquisition, target convergence bus construction, cumulative path length calculation, equal arc length division, and discrete trimming position generation, and sends motion commands to the motion control card. The motion control card is connected to the radial feed mechanism, axial feed mechanism, and grinding tool drive mechanism via EtherCAT (Ethernet Automation Technology) bus, and to a frequency converter via Modbus (Industrial Communication Protocol) bus. The frequency converter controls the operation of the rotary mechanism and simultaneously receives origin, limit, and running status signals.

[0049] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for trimming silicon carbide green tubes, applied to a silicon carbide green tube trimming apparatus, characterized in that, The blank trimming method includes: S1, obtain the coordinates of the boundary teaching point and the convergence depth of the convergence region to be processed in the axial section of the green tube; S2, construct the target convergence generatrix based on the boundary teaching point coordinates and convergence processing depth, and determine the relationship between the radial coordinates and axial coordinates of the target convergence generatrix; S3, divide the target convergence bus into multiple equal arc length segments according to the cumulative path length, determine the discrete blanking position data according to the division position of each equal arc length segment, and form a discrete blanking position sequence. S4, according to the discrete trimming position sequence, the grinding tool of the trimming device is controlled to move sequentially to each discrete trimming position along the radial and axial directions, and the dwell trimming is performed at each discrete trimming position in the rotating state of the silicon carbide green tube until the trimming of the area corresponding to the target convergence generatrix is ​​completed.

2. The method for trimming silicon carbide green tubes according to claim 1, characterized in that, Before the step of obtaining the coordinates of the boundary teaching points and the convergence depth of the convergence region to be processed within the axial section of the green tube, the method further includes: The silicon carbide green tube is clamped in the rotary mechanism, and the axis of the silicon carbide green tube is adjusted to correspond with the rotation axis of the rotary mechanism. Control the grinding tool to move to the preset machining start position, determine the current radial and axial positions of the grinding tool as the process coordinate origin, and establish a process coordinate system based on the process coordinate origin; The radial and axial coordinates in the target convergence generatrix and discrete blank trimming position data are both represented using the process coordinate system.

3. The method for trimming silicon carbide green tubes according to claim 1, characterized in that, The boundary teaching point coordinates include the first boundary teaching point coordinates and the second boundary teaching point coordinates, and the first boundary teaching point and the second boundary teaching point have the same axial coordinates; The expression for the radial coordinates of the center of convergence is: ； The expression for the radial half-axis length of the target convergence generatrix is: ； The expression for the target convergence bus is: ； in, Let be the radial coordinates of the first boundary teaching point. The radial coordinates of the second boundary teaching point are: Let be the axial coordinates of the first boundary teaching point and the second boundary teaching point. Let be the radial coordinate of the convergence center, a be the radial feature dimension of the target convergence generatrix, H be the convergence processing depth, X be the radial coordinate of any position on the target convergence generatrix, and Z be the axial coordinate of that any position.

4. The method for trimming silicon carbide green tubes according to claim 3, characterized in that, The target convergence bus is expressed in parametric form as follows: ； Where θ is the curve parameter of the target convergence generatrix, and 0 ≤ θ ≤ π / 2. Here are the radial coordinates corresponding to the curve parameter θ. Here is the axial coordinate corresponding to the curve parameter θ; Within the range of curve parameters, multiple parameter values ​​are selected sequentially. The coordinates of the computational nodes corresponding to each parameter value are determined according to the parameter form. The expression for the straight-line distance between adjacent computational nodes is: ； in, Let be the radial coordinate of the i-th computation node. Let be the axial coordinate of the i-th computation node. Let be the radial coordinate of the (i+1)th computation node. Let be the axial coordinate of the (i+1)th computation node. Let be the straight-line distance between the i-th computing node and the (i+1)-th computing node, where i is the sequential number of the computing node; then, the path lengths between adjacent computing nodes are accumulated sequentially to obtain the cumulative path length corresponding to each computing node and the total arc length of the target convergence bus.

5. The method for trimming silicon carbide green tubes according to claim 4, characterized in that, The step of determining the discrete blank-repairing position data based on the segmentation position of each equal arc length segment includes: The total arc length of the target convergence bus is divided equally according to the preset number of steps to obtain the target cumulative path length corresponding to each equal arc length segment. Determine the adjacent computing node intervals where the cumulative path length of each target lies from the cumulative path lengths corresponding to each computing node; Interpolation is performed based on the correspondence between the cumulative path length and curve parameters within the adjacent calculation node interval to obtain the curve parameters corresponding to the cumulative path length of each target. Substitute the obtained curve parameters into the parameter expression of the target convergence generatrix to obtain the radial and axial coordinates corresponding to each discrete trimming position. The discrete trimming position sequence is formed according to the order of each discrete trimming position on the target convergence generatrix.

6. The method for trimming silicon carbide green tubes according to claim 1, characterized in that, The step of controlling the grinding tool to move sequentially to each discrete trimming position along the radial and axial directions according to the discrete trimming position sequence includes: Obtain the radial and axial coordinates from the current discrete blanking position data. Control the radial feed mechanism to generate radial displacement based on the radial coordinates and control the axial feed mechanism to generate axial displacement based on the axial coordinates, thereby moving the grinding tool to the current discrete blanking position. When the radial feed mechanism reaches the target radial coordinate and the axial feed mechanism reaches the target axial coordinate, the radial feed and axial feed are terminated, the cutting timer corresponding to the current discrete blanking position is started, and the grinding tool is driven to rotate and the silicon carbide green tube is driven to rotate. When the cutting time reaches the set cutting time, the radial and axial coordinates in the next discrete blanking position data are obtained.

7. The method for trimming silicon carbide green tubes according to claim 6, characterized in that, Before the step of obtaining the radial and axial coordinates in the current discrete trimming position data, a straight pipe section trimming step is also included: Obtain the axial machining termination position, axial layered feed rate, radial machining termination position, radial inter-row feed rate, and cutting time of the straight pipe section; The grinding tool is controlled to feed along the axial direction layer by layer according to the axial layer feed amount, and the tool is stopped and cut at each layer position. When the axial machining termination position is reached, the grinding tool is controlled to return to the axial starting position and feed the radial inter-row feed amount radially until the radial machining termination position is reached.

8. The method for trimming silicon carbide green tubes according to claim 6, characterized in that, The step of moving the grinding tool to the current discrete blank-cutting position further includes: The motion control bus status, the servo status of the radial and axial feed mechanisms, the grinding tool drive status, and the motion duration are periodically acquired. Based on the acquired status, bus anomalies, servo anomalies, and motion timeouts are identified. In response to any anomaly, terminate radial feed, axial feed, grinding tool drive, and silicon carbide green tube rotation, and record the current target position, processing status, and elapsed cutting time.

9. The method for trimming silicon carbide green tubes according to claim 8, characterized in that, After the steps of recording the current target position, processing status, and elapsed cutting time, the method further includes: After the anomaly is resolved, check the operating status of the grinding tool and the rotary mechanism; When the processing state is the dwell and trimming state, the remaining cutting time is determined based on the set cutting time and the already executed cutting time, and the remaining cutting is performed; When the processing state is a position transition state, the current target position is called, and the grinding tool is controlled to move from the current position to the current target position to continue the dwell dressing.

10. A silicon carbide green tube trimming device, characterized in that, Including racks; The frame is provided with an X-axis crossbeam extending in the horizontal direction, and a Z-axis column extending in the vertical direction is suspended from the X-axis crossbeam. A spherical grinding head is provided at one end of the Z-axis column. A rotary mechanism is provided, which is arranged opposite to the ball grinding head along the extension direction of the Z-axis column. The rotary mechanism includes a drive mechanism, a reduction mechanism and a chuck. The drive mechanism drives the chuck through the reduction mechanism, and the silicon carbide green tube is vertically clamped in the chuck.

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