Uniform wall thickness control method and system based on on-machine measurement

Abstract

The invention discloses a uniform wall thickness control method and system based on on-machine measurement, and relates to the technical field of machining precision control, and the method comprises the steps: employing an isoparametric method to plan a measurement point on a theoretical curved surface of a part, generating a path which is detected in the normal direction of the measurement point, and obtaining an actual coordinate and a wall thickness through on-machine measurement of a contact type ultrasonic measuring head; calculating a shape deviation and a wall thickness deviation, and obtaining a compensation amount and a compensation point location based on a wall thickness compensation mode or a shape-followed wall thickness compensation mode; a reconstruction curved surface is generated through the B-spline curved surface fitting compensation point location; discretizing the theoretical tool path, projecting and adjusting the tool contact to the reconstructed curved surface, and generating a self-adaptive machining program; and controlling the machine tool to execute compensation processing. According to the method, full-process automation of measurement, calculation and machining is achieved, the operation difficulty is reduced, accurate compensation can be conducted for different position deviations of the part, the wall thickness uniformity and the machining efficiency are improved, and the method is suitable for complex deformation scenes such as large aeronautical parts.

Description

A method and system for uniform wall thickness control based on in-machine measurement Technical Field

[0001] This invention relates to the field of machining precision control technology, and in particular to a method and system for uniform wall thickness control based on in-machine measurement. Background Technology

[0002] As core components of aviation equipment, the machining accuracy of large aerospace parts directly affects the overall performance and operational safety of the equipment. During the machining or forming process of these parts, various factors such as cutting forces and the release of initial residual stress can easily cause irregular deformation, leading to deviations between the actual wall thickness and the target machining wall thickness (theoretical wall thickness), as shown in Figure 1. If the preset theoretical machining program is continued, it is highly likely that the wall thickness of the part will be too thin or too thick in certain areas, failing to meet the stringent requirements for wall thickness uniformity in aerospace parts, and even causing problems such as part scrapping and operational risks to the equipment. Therefore, precise control of the workpiece wall thickness during the machining process is of crucial practical significance.

[0003] To address the aforementioned wall thickness deviation problem, two commonly used wall thickness control schemes have been developed in the existing technology. One scheme involves manually collecting wall thickness data using an ultrasonic thickness gauge. Operators then manually calculate the wall thickness deviation and compensation values ​​at various points based on the collected data, ultimately determining a unified final compensation value. This final compensation value is then used to adjust the machining process through tool compensation. The other scheme utilizes computer-aided manufacturing (CAM) software to create machining toolpaths (such as drilling cycles), converting them into measurement paths to drive the machine tool to collect wall thickness data. Subsequent compensation machining is also performed by manually calculating a single compensation value.

[0004] However, existing technical solutions have significant drawbacks and are difficult to meet the high-precision and high-efficiency wall thickness control requirements of large aerospace parts: Firstly, in the wall thickness detection process, the method of manually collecting data with a handheld ultrasonic thickness gauge relies heavily on the operator's experience and operational standardization, which not only results in low detection efficiency but also makes it easy to compromise data accuracy due to human error. Secondly, the method of converting CAM machining paths into measurement paths involves a cumbersome and complex process of generating measurement points and defining measurement paths, which places high demands on the professional skills of programmers and increases the technical application threshold and operating costs.

[0005] Secondly, in the wall thickness control and compensation stage, existing solutions all calculate a single compensation value based on limited wall thickness detection data. The determination of this compensation value is easily affected by the distribution of wall thickness deviations in the workpiece. It can only distribute the risk of over-cutting wall thickness evenly, and cannot provide targeted compensation for specific wall thickness deviations at different locations of the part. This extensive compensation method results in poor compensation effect, and is particularly difficult to adapt to the processing scenarios of large aerospace parts with complex wall thickness deformation, and cannot fundamentally solve the problem of wall thickness uniformity control.

[0006] In summary, existing wall thickness control technologies have significant shortcomings in terms of detection efficiency, data accuracy, and compensation targeting. There is an urgent need for a more efficient, accurate, and adaptable uniform wall thickness control technology to meet the processing quality requirements of large aerospace parts. Summary of the Invention

[0007] To address these issues, embodiments of the present invention provide a uniform wall thickness control method and system based on in-machine measurement, which solves the problems in the prior art where wall thickness detection relies on manual labor or cumbersome CAM path conversion processes, requires high programming skills and is difficult to guarantee accuracy and efficiency, and a single compensation value cannot provide targeted compensation for wall thickness deviations at different locations of the part and is difficult to adapt to complex deformation scenarios.

[0008] To address the aforementioned technical problems, this invention provides a method for uniform wall thickness control based on in-machine measurement. The method includes the following steps: S1: Planning multiple measurement points on the theoretical curved surface of the part to be processed, generating a measurement path and sending it to the machine tool, driving a contact ultrasonic probe mounted on the machine tool to perform in-machine measurement, and obtaining the actual coordinates and actual wall thickness of each measurement point; S2: Calculating shape deviation and wall thickness deviation based on the theoretical coordinates, actual coordinates, and actual wall thickness of each measurement point, and calculating the compensation amount for each point based on the shape deviation and / or wall thickness deviation; and calculating the compensation amount based on the theoretical coordinates, theoretical normal, and corresponding compensation amount of each measurement point. S3: Calculate the coordinates of the compensation points; S4: Use all the calculated compensation points to perform surface fitting to generate a reconstructed surface; S5: Discretize the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and the corresponding theoretical tool contact point; Project the theoretical tool contact point onto the reconstructed surface to obtain the projection point and the projection point normal; Adjust the theoretical tool contact point and the theoretical tool position point according to the projection point and the projection point normal to obtain the actual tool contact point and the actual tool position point, and reassemble the actual tool position point with the corresponding actual tool axis direction to generate an adaptive machining program; S6: Control the machine tool to perform compensation machining on the part using the adaptive machining program.

[0009] Preferably, in step S1, generating the measurement path specifically includes: automatically generating a measurement path that allows the ultrasonic probe to probe along the normal of each measurement point based on the measurement range, number of measurement points, and safety height parameters specified by the user.

[0010] Preferably, in step S1, the in-machine measurement process includes: for each measurement point, controlling the ultrasonic probe to first move to a safe point, adjusting the tool axis direction to coincide with the theoretical normal of the measurement point, then moving to an approach point, and then contacting the workpiece surface at a detection feed speed and triggering ultrasonic measurement.

[0011] Preferably, in step S1, the method of planning multiple measurement points on the theoretical curved surface of the part to be processed using the isoparametric method includes: performing isoparametric discretization on the U-direction and V-direction parameter lines of the curved surface respectively, and combining the discretized parameter values ​​to obtain a grid-like set of measurement points distributed on the curved surface.

[0012] Preferably, in step S2, the calculation of the compensation amount adopts a wall thickness-only compensation mode, and the calculation formula is: ,in, For compensation amount, For wall thickness deviation, , This is the actual wall thickness. Theoretical wall thickness.

[0013] Preferably, in step S2, the compensation amount is calculated using a conformal wall thickness compensation mode, and the calculation formula is as follows: ,in, For compensation amount, For shape deviation, , Represents the theoretical coordinates of the measured point Pointing to actual coordinates The vector, This represents the unit normal vector at the theoretical measurement point. , This is the actual wall thickness. Theoretical wall thickness.

[0014] Preferably, in step S2, the formula for calculating the coordinates of the compensation point is: ,in, To compensate for the coordinates of the points, The theoretical coordinates of the measurement point, For compensation, N represents the unit normal vector at the theoretical measurement point.

[0015] Preferably, in step S3, the surface fitting adopts the B-spline surface fitting method to fit the compensation points distributed in a grid into a smooth reconstructed surface.

[0016] Preferably, in step S4, the specific method for adjusting the theoretical tool contact point and the theoretical tool position point includes: offsetting the theoretical tool contact point along the direction of the line connecting it and the projection point, and taking the offset point as the actual tool contact point; calculating the actual tool position point based on the actual tool contact point and tool information; and taking the normal of the projection point as the actual tool axis direction corresponding to the actual tool position point.

[0017] This invention also provides a uniform wall thickness control system based on in-machine measurement. This system is used to implement the aforementioned uniform wall thickness control method based on in-machine measurement. Specifically, it includes: a measurement planning and data acquisition module, used to plan multiple measurement points on the theoretical curved surface of the part to be processed, generate a measurement path and send it to the machine tool, drive a contact ultrasonic probe mounted on the machine tool to perform in-machine measurement, and obtain the actual coordinates and actual wall thickness of each measurement point; a compensation calculation module, used to calculate the shape deviation and wall thickness deviation based on the theoretical coordinates, actual coordinates, and actual wall thickness of each measurement point, and calculate the compensation amount for each point based on the shape deviation and / or wall thickness deviation; and calculate the compensation amount for each point based on the theoretical coordinates, theoretical normal, and corresponding... The system calculates the compensation amount and obtains the coordinates of the compensation points; the surface reconstruction module is used to perform surface fitting using all the calculated compensation points to generate a reconstructed surface; the adaptive toolpath generation module is used to discretize the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and the corresponding theoretical tool contact point; the theoretical tool contact point is projected onto the reconstructed surface to obtain the projection point and the projection point normal; the theoretical tool contact point and the theoretical tool position point are adjusted according to the projection point and the projection point normal to obtain the actual tool contact point and the actual tool position point, and the actual tool position point is recombined with the corresponding actual tool axis direction to generate an adaptive machining program; the machining control module is used to control the machine tool to perform compensated machining on the part using the adaptive machining program.

[0018] As can be seen from the above technical solutions, the present invention application has the following beneficial effects: (1) The present invention adopts the isoparametric method to automatically plan grid-shaped measurement points. Users only need to specify key parameters such as measurement range, number of points and safety height to automatically generate the measurement path along the normal direction of the measurement point. There is no need for complex CAM path conversion or professional programming ability. At the same time, through contact ultrasonic on-machine measurement, the human error of manual handheld measurement is avoided, which greatly improves the efficiency and accuracy of wall thickness data acquisition and solves the problem of cumbersome detection process and difficulty in balancing accuracy and efficiency in the existing technology.

[0019] (2) This invention supports two modes: wall thickness compensation only and conformal wall thickness compensation. It calculates the exclusive compensation amount based on the actual shape deviation and wall thickness deviation of each measurement point, and then generates the reconstructed surface through B-spline surface fitting to achieve accurate adaptation to the deviation of different positions of the part. Compared with the single compensation value scheme of the prior art, it can effectively cope with complex deformation scenarios such as large aerospace parts, significantly improve the uniformity of wall thickness, and avoid processing defects of local thinness or thickness.

[0020] (3) The software realizes the entire process of measurement path generation, data acquisition, compensation calculation, surface reconstruction, adaptive toolpath generation and compensation machining. There is no need for manual intervention in key links such as compensation calculation and toolpath adjustment. This avoids the problem of errors caused by manual calculation and reduces the time spent on process connection. At the same time, the automation program is solidified to ensure the uniformity of the processing flow for different batches and different parts, and improves the stability of processing quality and production efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below. Referring to the accompanying drawings will make the features and advantages of the present invention clearer. The drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Specifically: Figure 1 is a schematic diagram of the wall thickness deviation of a part in the background art of the present invention; Figure 2 is a flowchart of a uniform wall thickness control method based on in-machine measurement provided by the present invention; Figure 3 is a schematic diagram of the in-machine ultrasonic measurement process in an embodiment of the present invention; Figure 4 is a schematic diagram of the distribution of measurement points on the isoparametric surface in an embodiment of the present invention; Figure 5 is a schematic diagram of surface measurement point planning in an embodiment of the present invention; Figure 6 is a schematic diagram of the compensation value calculation principle in an embodiment of the present invention; Figure 7 is a schematic diagram of compensation point calculation in an embodiment of the present invention; Figure 8 is a schematic diagram of the reconstructed surface in an embodiment of the present invention; Figure 9 is a schematic diagram of the toolpath mapping principle in an embodiment of the present invention; Figure 10 is a schematic diagram of parameter examples for two consecutive measurement points on the machined surface in an embodiment of the present invention; Figure 11 is a block diagram of a uniform wall thickness control system based on in-machine measurement provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: To address the problems in existing technologies where wall thickness detection relies on manual labor or CAM path conversion processes that are cumbersome, require highly skilled programmers, and struggle to guarantee accuracy and efficiency, and where a single compensation value cannot specifically compensate for wall thickness deviations at different locations on the part and is difficult to adapt to complex deformation scenarios, as shown in Figure 2, this invention proposes a uniform wall thickness control method based on in-machine measurement. This method includes the following steps: S1: Planning multiple measurement points on the theoretical curved surface of the part to be processed, generating a measurement path and sending it to the machine tool, driving the contact ultrasonic probe installed on the machine tool to perform in-machine measurement, and obtaining the actual coordinates and actual wall thickness of each measurement point; S2: Calculating the shape deviation and wall thickness deviation based on the theoretical coordinates, actual coordinates, and actual wall thickness of each measurement point, and calculating the compensation amount for each point based on the shape deviation and / or wall thickness deviation; and calculating the compensation amount based on the theoretical coordinates, theoretical normal, and corresponding compensation amount of each measurement point. S3: Calculate the coordinates of the compensation points; S4: Use all the calculated compensation points to perform surface fitting and generate a reconstructed surface; S5: Discretize the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and the corresponding theoretical tool contact point; Project the theoretical tool contact point onto the reconstructed surface to obtain the projection point and the projection point normal; Adjust the theoretical tool contact point and the theoretical tool position point according to the projection point and the projection point normal to obtain the actual tool contact point and the actual tool position point, and reassemble the actual tool position point with the corresponding actual tool axis direction to generate an adaptive machining program; S6: Control the machine tool to perform compensation machining on the part using the adaptive machining program.

[0024] As can be seen from the above technical solution, this invention proposes a uniform wall thickness control method based on in-machine measurement. First, step S1 is executed, where multiple measurement points are planned on the theoretical curved surface of the part to be processed, and a measurement path is generated. The contact ultrasonic probe mounted on the machine tool is then driven to complete the in-machine measurement, efficiently acquiring the actual coordinates and actual wall thickness of each measurement point. This reduces the operational threshold for measurement path planning and avoids human error in manual measurement, ensuring the efficiency and accuracy of data acquisition. Next, step S2 is executed, where the shape deviation and wall thickness deviation of each point are calculated based on the measured data and theoretical data. Then, the compensation amount and coordinates of each compensation point are specifically solved, breaking through the limitations of traditional coarse compensation based on a single compensation value and achieving uniform wall thickness control for zero-weighted components. The process involves several steps: First, precise adaptation to different positional deviations of the part. Second, step S3 uses all compensation points to perform surface fitting to generate a reconstructed surface, providing a precise surface model that reflects the actual deviation requirements of the part for subsequent toolpath adjustments, effectively adapting to complex deformation scenarios. Third, step S4 discretizes the theoretical toolpath, projects the theoretical tool contact points onto the reconstructed surface, and adjusts the tool contact points, tool position points, and tool axis directions to regenerate an adaptive machining program, ensuring precise matching between the toolpath and the actual deviation of the part. Finally, step S5 is executed, controlling the machine tool to complete the compensation machining according to the adaptive machining program, ultimately achieving uniform control of the part's wall thickness, significantly improving machining quality and efficiency, and perfectly solving the pain points of cumbersome inspection and poor compensation targeting in existing technologies.

[0025] The core of this invention, a uniform wall thickness control method based on in-machine measurement, lies in obtaining the wall thickness and shape deviations of a part through in-machine contact ultrasonic measurement. This is followed by compensation calculations, surface reconstruction, and toolpath adjustment to generate an adaptive machining program, ultimately achieving uniform wall thickness control. The method specifically includes steps S1 to S5, which are described in detail below with specific parameters, formulas, and operational details.

[0026] Step S1: Measurement Planning and On-Machine Data Acquisition. The core of this step is to plan measurement points on the theoretical curved surface and generate measurement paths, drive the ultrasonic probe to complete on-machine measurement, and obtain actual coordinates and actual wall thickness data.

[0027] 1. Measurement Point Planning: Measurement points are planned using the isoparametric method. The theoretical surface of the part to be processed is a parametric surface, containing parametric lines in both the U and V directions. and As shown in Figure 4, first specify the range on the U-axis parameter line. V-direction parameter line specifies the range Then, the U-direction parameter lines are discretized using equal-parameter discretization to obtain the parameter set. The parameter set is obtained by performing isoparametric discretization on the V-direction parameter line. Combine the two sets of parameters to form indivual parameter (in , Substituting these values ​​into the theoretical surface equation yields a grid-like distribution of measurement points, as shown in Figure 5.

[0028] 2. Measurement Path Generation: Users only need to specify the measurement range (i.e., the U and V directions mentioned above), the number of measurement points (n and m values), and the safety height parameter, and the system will automatically generate the measurement path. This path ensures that the ultrasonic probe probes along the theoretical normal of each measurement point, avoiding measurement errors caused by deviations in the probe direction.

[0029] 3. In-machine measurement execution: The generated measurement path is converted into an NC program through post-processing and sent to the machine tool to drive the contact ultrasonic probe installed on the machine tool to perform the measurement. As shown in Figure 3, the measurement process for a single measurement point is as follows: The ultrasonic probe moves from the previous measurement point (the first measurement point starts from the user-specified initial position) to the safety point S; the tool axis direction is adjusted to coincide with the theoretical normal of the current measurement point (e.g., the normals of the measurement point N1 and N2); it moves rapidly to the approach point A; it approaches the workpiece surface at a preset detection feed rate, and after reaching the designated position, it triggers the ultrasonic measurement signal to obtain the actual coordinates of the measurement point. and actual wall thickness After the measurement is completed, the ultrasonic probe retracts to the safety point S and enters the cycle of the next measurement point until all measurement points are completed and the measurement data is returned to the software.

[0030] Step S2: Calculation of Compensation Amount and Compensation Point Location. This step is based on the measured data obtained in step S1. The shape deviation, wall thickness deviation and compensation amount are calculated, and then the coordinates of the compensation point location are obtained.

[0031] 1. Deviation Calculation: Shape Deviation The calculation formula is: ,in Theoretical coordinates of the measurement point Pointing to actual coordinates The vector, The unit normal vector at the theoretical measurement point; wall thickness deviation. The calculation formula is: ,in This is the theoretical wall thickness at the measurement point.

[0032] 2. Compensation Calculation: Two compensation modes are provided, which users can choose according to their processing needs: Wall thickness only compensation mode: Compensation amount This method only compensates for wall thickness deviations and is suitable for scenarios with small shape deformations; conformal wall thickness compensation mode: compensation amount It combines shape deviation and wall thickness deviation for comprehensive compensation, making it suitable for scenarios with complex shape deformation.

[0033] 3. Calculation of compensation point coordinates: The calculation formula is as follows ,in To obtain the compensation point coordinates, substitute the compensation amounts corresponding to all measurement points into the formula to obtain a grid-like set of compensation points. The calculation process is illustrated in Figures 6 and 7.

[0034] Step S3: Generating the reconstructed surface. This step involves using the B-spline surface fitting method to fit the mesh-like compensation point set obtained in step S2, generating a smooth reconstructed surface. As shown in Figure 8. During the fitting process, the smoothness and approximation of the B-spline surface are utilized to ensure that the reconstructed surface can accurately reflect the deviation compensation requirements of each position of the part, providing an accurate surface model for subsequent toolpath adjustment.

[0035] Step S4: Adaptive machining program generation. This step generates an adaptive machining program through toolpath discretization, projection mapping, and parameter adjustment.

[0036] 1. Theoretical Toolpath Discretization: Obtain the theoretical toolpath from the preset theoretical machining program. This toolpath consists of tool points and the corresponding tool axis directions. Discretize the theoretical toolpath into multiple theoretical tool points. Based on the tool position point, tool axis direction, and tool parameters (such as tool radius and length), the theoretical tool contact point corresponding to each theoretical tool position point is calculated. .

[0037] 2. Tool contact point projection: Project each theoretical tool contact point onto the reconstructed surface generated in step S3. Projection, to obtain the projection point and the normal at the projection point And calculate the distance between the theoretical tool contact point and the projected point. This distance is the deviation value of the knife contact point.

[0038] 3. Adjustment of tool contact point and tool position: Calculation of actual tool contact point: The theoretical tool contact point... Along its projection point The direction of the line Offset, offset amount is To obtain the actual tool contact point Actual tool contact point calculation: based on the actual tool contact point The actual tool position point is obtained by back-calculating the tool parameters (such as tool radius and length); the actual tool axis direction is determined by: the normal of the projection point. This refers to the actual tool axis direction corresponding to the actual tool position point.

[0039] 4. Adaptive Machining Program Reassembly: All adjusted actual tool positions are reassembled with their corresponding actual tool axis directions to generate an adaptive machining program. The toolpath mapping principle is shown in Figure 9.

[0040] Step S5: Compensation machining sends the generated adaptive machining program to the machine tool, controls the machine tool to perform compensation machining, and achieves uniform wall thickness control.

[0041] The following example, using two consecutive measurement points shown in Figure 10, further illustrates the implementation process of this method: assuming a theoretical wall thickness... The parameters of the two measurement points are as follows: Point Theoretical coordinates , legal direction ; Measured coordinates Measured wall thickness ;point Theoretical coordinates , legal direction ; Measured coordinates Measured wall thickness The calculation process is as follows: 1. Shape deviation: , 2. Wall thickness deviation: , 3. Compensation Amount (Follow-Shape Mode): , 4. Compensation points: , .

[0042] After calculating all points in sequence, surface fitting and toolpath mapping are performed to finally generate an adaptive machining program.

[0043] Example 2: As shown in Figure 11, this invention provides a uniform wall thickness control system based on in-machine measurement. This system is used to implement the uniform wall thickness control method based on in-machine measurement in Example 1 above. Specifically, it includes: a measurement planning and data acquisition module 100, used to plan multiple measurement points on the theoretical surface of the part to be processed, generate measurement paths and send them to the machine tool, drive the contact ultrasonic probe installed on the machine tool to perform in-machine measurement, and obtain the actual coordinates and actual wall thickness of each measurement point; a compensation calculation module 200, used to calculate the shape deviation and wall thickness deviation according to the theoretical coordinates, actual coordinates and actual wall thickness of each measurement point, and calculate the compensation amount of each point based on the shape deviation and / or wall thickness deviation; and calculate the compensation amount of each point based on the theoretical coordinates, actual coordinates and actual wall thickness of each measurement point. The system calculates the coordinates of the compensation points based on the normal and corresponding compensation amount. A surface reconstruction module 300 uses all calculated compensation points to fit a surface and generate a reconstructed surface. An adaptive toolpath generation module 400 discretizes the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and corresponding theoretical tool contact point. The theoretical tool contact point is projected onto the reconstructed surface to obtain the projection point and its normal. Based on the projection point and its normal, the theoretical tool contact point and theoretical tool position point are adjusted to obtain the actual tool contact point and actual tool position point. The actual tool position point is then recombined with the corresponding actual tool axis direction to generate an adaptive machining program. A machining control module 500 controls the machine tool to perform compensated machining on the part using the adaptive machining program.

[0044] This embodiment provides a uniform wall thickness control system based on in-machine measurement, used to implement the aforementioned uniform wall thickness control method based on in-machine measurement. Therefore, the specific implementation of the uniform wall thickness control system based on in-machine measurement can be found in the previous section on the embodiment of the uniform wall thickness control method based on in-machine measurement. For example, the measurement planning and data acquisition module 100, the compensation calculation module 200, the surface reconstruction module 300, the adaptive toolpath generation module 400, and the machining control module 500 are respectively used to implement steps S1, S2, S3, S4, and S5 in the aforementioned uniform wall thickness control method based on in-machine measurement. Therefore, the specific implementation can be referred to the description of the corresponding embodiments. To avoid redundancy, it will not be repeated here.

[0045] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0046] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0047] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for controlling uniform wall thickness based on in-machine measurement, characterized in that, Includes the following steps: S1: Plan multiple measurement points on the theoretical curved surface of the part to be processed, generate measurement paths and send them to the machine tool, drive the contact ultrasonic probe installed on the machine tool to perform on-machine measurement, and obtain the actual coordinates and actual wall thickness of each measurement point; S2: Calculate the shape deviation and wall thickness deviation based on the theoretical coordinates, actual coordinates, and actual wall thickness of each measurement point. Calculate the compensation amount for each point based on the shape deviation and / or wall thickness deviation. Calculate the coordinates of the compensation point based on the theoretical coordinates, theoretical normal, and corresponding compensation amount of each measurement point. S3: Perform surface fitting using all calculated compensation points to generate a reconstructed surface. S4: Discretize the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and the corresponding theoretical tool contact point. Project the theoretical tool contact point onto the reconstructed surface to obtain the projection point and projection point normal. Adjust the theoretical tool contact point and theoretical tool position point based on the projection point and projection point normal to obtain the actual tool contact point and actual tool position point. Reassemble the actual tool position point with the corresponding actual tool axis direction to generate an adaptive machining program. S5: Control the machine tool to perform compensated machining on the part using the adaptive machining program.

2. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S1, generating the measurement path specifically includes: automatically generating a measurement path that allows the ultrasonic probe to probe along the normal of each measurement point based on the measurement range, number of measurement points, and safety height parameters specified by the user.

3. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S1, the in-machine measurement process includes: for each measurement point, controlling the ultrasonic probe to first move to a safe point, adjusting the tool axis direction to coincide with the theoretical normal of the measurement point, then moving to an approach point, and then contacting the workpiece surface at a detection feed speed and triggering ultrasonic measurement.

4. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S1, the method of planning multiple measurement points on the theoretical curved surface of the part to be processed using the isoparametric method includes: performing isoparametric discretization on the U-direction and V-direction parameter lines of the curved surface respectively, and combining the discretized parameter values ​​to obtain a grid-like set of measurement points distributed on the curved surface.

5. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S2, the compensation amount is calculated using a wall thickness-only compensation mode, and the calculation formula is as follows: ,in, For compensation amount, For wall thickness deviation, ， This is the actual wall thickness. Theoretical wall thickness.

6. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S2, the compensation amount is calculated using a conformal wall thickness compensation mode, and the calculation formula is as follows: ,in, For compensation amount, For shape deviation, ， Represents the theoretical coordinates of the measured point Pointing to actual coordinates The vector, This represents the unit normal vector at the theoretical measurement point. ， This is the actual wall thickness. Theoretical wall thickness.

7. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S2, the formula for calculating the coordinates of the compensation point is: ,in, To compensate for the coordinates of the points, The theoretical coordinates of the measurement point, For compensation, N represents the unit normal vector at the theoretical measurement point.

8. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S3, the surface fitting adopts the B-spline surface fitting method to fit the compensation points distributed in a grid into a smooth reconstructed surface.

9. The uniform wall thickness control method based on in-machine measurement according to claim 1, characterized in that, In step S4, the specific method for adjusting the theoretical tool contact point and the theoretical tool position point includes: offsetting the theoretical tool contact point along the line connecting it and the projection point, and taking the offset point as the actual tool contact point; calculating the actual tool position point based on the actual tool contact point and tool information; and taking the normal of the projection point as the actual tool axis direction corresponding to the actual tool position point.

10. A uniform wall thickness control system based on in-machine measurement, characterized in that, The system is used to implement the uniform wall thickness control method based on in-machine measurement as described in any one of claims 1 to 9, specifically including: a measurement planning and data acquisition module, used to plan multiple measurement points on the theoretical curved surface of the part to be processed, generate a measurement path and send it to the machine tool, drive the contact ultrasonic probe installed on the machine tool to perform in-machine measurement, and obtain the actual coordinates and actual wall thickness of each measurement point; a compensation calculation module, used to calculate the shape deviation and wall thickness deviation respectively according to the theoretical coordinates, actual coordinates and actual wall thickness of each measurement point, and calculate the compensation amount of each point based on the shape deviation and / or wall thickness deviation; and calculate the compensation amount of each point according to the theoretical coordinates, theoretical normal and corresponding compensation amount of each measurement point. The system includes: a compensation point coordinate module; a surface reconstruction module for fitting a surface using all calculated compensation points to generate a reconstructed surface; an adaptive toolpath generation module for discretizing the theoretical toolpath in the theoretical machining program to obtain the theoretical tool position point and the corresponding theoretical tool contact point; projecting the theoretical tool contact point onto the reconstructed surface to obtain the projection point and the projection point normal; adjusting the theoretical tool contact point and the theoretical tool position point according to the projection point and the projection point normal to obtain the actual tool contact point and the actual tool position point, and recombining the actual tool position point with the corresponding actual tool axis direction to generate an adaptive machining program; and a machining control module for controlling the machine tool to perform compensated machining on the part using the adaptive machining program.

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