A workpiece in-situ detection device and method based on CNC machine tools

Abstract

The present invention belongs to the technical field of workpiece detection, and discloses a workpiece in-situ detection device and method based on a numerically controlled machine tool. The workpiece in-situ detection device is integrated on the numerically controlled machine tool, and the workpiece in-situ detection device is installed on the X-axis of the numerically controlled machine tool together with the grinding axis, and ensures that the measuring axis and the grinding axis are of the same height and parallel; the workpiece spindle is installed on the Z-axis of the numerically controlled machine tool, and ensures that the workpiece spindle, the measuring axis and the grinding axis are coplanar. By using the workpiece in-situ detection device on the numerically controlled machine tool, combined with the three-axis motion of the numerically controlled machine tool, point-by-point measurement of the workpiece surface is achieved, thereby accurately obtaining the workpiece contour information. This method has the advantages of high measurement accuracy, fast measurement speed, and simple operation, and is suitable for detecting workpieces of various shapes and sizes. Through verification of specific embodiments, the technical solution of the present invention has achieved good results in practical applications, providing an efficient and accurate means for online monitoring and quality control of workpiece processing quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of workpiece detection, and relates to an on-site detection device and method for workpiece contour based on a numerically controlled machine tool. Background Art

[0002] In modern manufacturing, workpiece contour accuracy is a key quality criterion. Traditional workpiece contour detection methods mostly rely on offline measurement, requiring the workpiece to be removed from the CNC machine tool and inspected using equipment such as a coordinate measuring machine. However, this method is not only time-consuming and labor-intensive, but also prone to introducing secondary errors, compromising measurement accuracy.

[0003] Among various measuring instruments currently available, coordinate measuring machines (CMMs) equipped with trigger / scanning probes remain the most widely used in industry, particularly when measuring large, high-precision freeform surfaces. Ren et al., in their study "ACurveNetwork Sampling Strategy for Measurement of Freeform Surfaces on CoordinateMeasuring Machines," demonstrated that measurement processes often aim to achieve a given level of sampling accuracy using the fewest samples possible to save time and improve efficiency. On the other hand, SD Phillips et al., in their study "The estimation of measurement uncertainty of small circular features measured by coordinate measuring machines," demonstrated that insufficient sampling can lead to deviations in the measurement of machined surface form errors and can become a major contributor to measurement uncertainty. R. Wilhelm et al., in their study "Task-specific uncertainty in coordinate measurement," also found that this becomes even more critical when it comes to the accuracy levels required for high-precision freeform surfaces in the micron to submicron range.

[0004] While some attempts have been made at in-situ inspection techniques, most have limitations. The review "Review on grinding wheel wear measurement methods" suggests that in-situ inspection can be achieved using traditional methods such as copying, acoustic emission, projection, or eddy current methods. However, these methods either suffer from low accuracy or are only suitable for specific workpiece and tool types, failing to meet the requirements for complex contours and high-precision inspection. Wang et al., in "On-Machine Precision Form Truing and In-Situ Measurement of Resin-Bonded Spherical Diamond Wheel," demonstrate that contour inspection can be performed using non-contact methods such as laser displacement sensors. However, these methods require a complex drive mechanism between the sensor and the workpiece, increasing the complexity of the inspection apparatus and being susceptible to workpiece surface roughness, resulting in reduced inspection accuracy. Yin et al., in "Dependant Gaussian processes regression for intelligent sampling of freeform and structured surfaces," also demonstrate that uniformly or randomly sampling the workpiece surface without considering geometric features can lead to low efficiency for blind sampling when data acquisition costs are high, resulting in a significant trade-off between sampling accuracy and inspection time. Therefore, it is particularly important to develop an intelligent device and method that can directly perform in-situ detection of workpiece contours on CNC machine tools. Summary of the Invention

[0005] The purpose of the present invention is to provide an intelligent on-site detection device and method for workpiece contours. By using a single-point probe on a CNC machine tool and combining it with the three-axis motion of the CNC machine tool, point-by-point measurement of the workpiece surface can be achieved, thereby accurately obtaining the workpiece contour information and providing strong support for online monitoring and quality control of the workpiece processing quality.

[0006] The technical solution of the present invention:

[0007] A workpiece in-position detection device for a CNC machine tool includes a workpiece in-position detection device integrated into the CNC machine tool. The workpiece in-position detection device is mounted on the X-axis of the CNC machine tool along with the grinding spindle, ensuring that the measuring axis and the grinding spindle are at the same height and parallel. The workpiece spindle is mounted on the Z-axis of the CNC machine tool, ensuring that the workpiece spindle, measuring axis, and grinding axis are coplanar.

[0008] Furthermore, the workpiece in-situ monitoring device includes a workpiece in-situ detection component, a control system and a corresponding data processing system. The control system is used to control the three-axis motion of the CNC machine tool, and the data processing system is used to receive, process and analyze the measurement data of the single-point probe.

[0009] Furthermore, the workpiece in-place detection component includes a workpiece in-place measurement probe, a workpiece in-place measurement probe head, a workpiece in-place measurement device Y-axis fine-tuning knob, a workpiece in-place measurement device X-axis fine-tuning knob, a workpiece in-place measurement device Z-axis adjustment knob, a workpiece in-place measurement device Z-axis fine-tuning knob, a workpiece in-place measurement turntable adapter plate, a workpiece in-place measurement turntable, a workpiece in-place measurement turntable support table, and a workpiece in-place measurement device reference surface. The workpiece in-place measurement probe is mounted on the workpiece in-place measurement probe head, and the workpiece in-place measurement probe head is mounted on the workpiece in-place measurement device reference surface.

[0010] The reference plane of the workpiece in-place measuring device is installed on the workpiece in-place measuring turntable adapter plate through the workpiece in-place measuring device Y-axis fine-tuning knob, the workpiece in-place measuring device X-axis fine-tuning knob, the workpiece in-place measuring device Z-axis adjustment knob and the workpiece in-place measuring device Z-axis fine-tuning knob. The reference plane of the workpiece in-place measuring device can adjust the plane space distance through the adjustment knob and the fine-tuning knob.

[0011] The workpiece in-place measurement turntable adapter plate is mounted on the workpiece in-place measurement turntable, which can adjust the angle of the workpiece in-place measurement probe. The workpiece in-place measurement turntable is mounted on the workpiece in-place measurement turntable adapter plate via the workpiece in-place measurement turntable support platform. The workpiece in-place measurement turntable adapter plate is connected to the X-axis of the CNC machine tool via bolts.

[0012] A method for in-situ detection of workpieces based on CNC machine tools includes the following five steps:

[0013] Step 1: Device calibration and positioning

[0014] First, adjust the spatial position of the workpiece in-situ measurement device, especially the measuring probe, to ensure proper connection between the probe and the CNC machine tool's control system. The probe's extension length and measuring angle are adjusted according to the shape and size of the workpiece. The CNC machine tool's positioning function ensures that the relative position of the workpiece and the in-situ monitoring device on the workbench is accurate and stable.

[0015] During device preparation and workpiece positioning, the following points should be noted:

[0016] The single-point probe can be made according to the material of the workpiece and the measurement accuracy requirements, ensuring that the hardness and wear resistance of the probe meet the measurement requirements.

[0017] The control system of the CNC machine tool should be preheated and calibrated to ensure measurement accuracy and stability.

[0018] Step 2: Measurement path planning and probe calibration

[0019] Based on the workpiece's shape and size, as well as the required measurement accuracy, measurement paths are planned within the data processing system. This path ensures that the probe covers all critical areas of the workpiece surface while avoiding collisions. Once planned, the measurement paths are imported into the CNC machine tool's control system.

[0020] The CNC machine tool's three-axis motion moves the probe along a predetermined path, while simultaneously recording the probe's actual coordinates at each location. The actual coordinates are compared with the theoretical coordinates, and the probe's extension length and measurement angle are adjusted until the deviation between the actual and theoretical coordinates is within the allowable range.

[0021] Step 3: Point-by-point measurement and data collection

[0022] After the probe is calibrated, the control system controls the three-axis motion of the CNC machine tool, ensuring that the probe contacts the workpiece surface point by point along the planned measurement path. During the measurement process, the single-point probe transmits the measurement data in real time to the data processing system. The data processing system then performs preliminary processing and stores the received data for subsequent analysis and processing.

[0023] During point-by-point measurement and data collection, the following points should be noted:

[0024] The movement speed of CNC machine tools should be moderate to avoid excessive speed that may cause inaccurate measurements or damage to the probe.

[0025] The measuring force of the probe should be moderate to avoid excessive force that may cause damage to the workpiece surface or inaccurate measurement.

[0026] Measurement data should be transmitted and saved in real time to ensure data integrity and accuracy.

[0027] Step 4: Data processing and contour reconstruction

[0028] The data processing system processes and analyzes the received measurement data. First, it filters and removes noise to improve accuracy and reliability. Then, it reconstructs the workpiece's contour model based on the measurement data. Contour reconstruction can use mathematical methods such as interpolation and fitting to generate a continuous contour curve or surface based on the coordinate information of the measured points.

[0029] During data processing and contour reconstruction, the following points need to be noted:

[0030] Appropriate algorithms and parameters should be selected for data filtering and denoising to avoid data distortion caused by excessive processing.

[0031] Appropriate algorithms and models should be selected for contour reconstruction to ensure the accuracy and reliability of the reconstruction results.

[0032] For complex workpiece contours, it may be necessary to combine and optimize multiple algorithms and models to improve the reconstruction effect.

[0033] Step 5: Output and evaluation of test results

[0034] The processed measurement data and reconstructed contour model are output to a designated output device or storage medium for user review and analysis. Simultaneously, the workpiece contour accuracy is evaluated based on the measurement data and comparative analysis results. The evaluation results can include indicators such as contour error and surface roughness, providing users with a reliable reference.

[0035] During the test result output and evaluation process, the following points should be noted:

[0036] The selection of output devices and storage media should meet user needs and confidentiality requirements.

[0037] The evaluation results should accurately reflect the contour accuracy and measurement error of the workpiece, providing users with a reliable reference.

[0038] For workpieces whose evaluation results do not meet the requirements, improvement suggestions should be made or re-measurement should be performed.

[0039] Beneficial effects of the present invention:

[0040] The present invention provides a workpiece in-situ detection device and method based on a CNC machine tool. By utilizing the workpiece in-situ detection device on the CNC machine tool, combined with the three-axis motion of the CNC machine tool, point-by-point measurement of the workpiece surface is achieved, thereby accurately acquiring workpiece contour information. This method offers the advantages of high measurement accuracy, fast measurement speed, and simple operation, and is suitable for detecting workpieces of various shapes and sizes. Specific examples have demonstrated that the technical solution of the present invention has achieved excellent results in practical applications, providing an efficient and accurate means for online monitoring and quality control of workpiece machining quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram of the in-situ measurement system of a workpiece implemented by the device of the present invention based on a CNC machine tool.

[0042] Figure 2 This is a schematic diagram of the height distribution of the present invention installed on a CNC machine tool, wherein the measuring axis of the workpiece in-position detection device, the grinding axis, and the workpiece spindle are in the same plane.

[0043] Figure 3The schematic diagram of the plane layout of the device of the present invention installed on a numerically controlled machine tool is shown in FIG. During measurement, the measuring axis, the grinding axis, and the workpiece spindle of the workpiece in-position detection device are parallel to each other.

[0044] Figure 4 It is a schematic diagram of the height structure of the workpiece in-situ detection device of the present invention, wherein the rotary axis is in the original position.

[0045] Figure 5 It is a schematic diagram of the horizontal structure of the workpiece in-situ detection device of the present invention, wherein the rotary axis rotates 90 degrees.

[0046] Figure 6 The measurement result of the workpiece in-situ detection device of the present invention on the standard ball. Workpiece in-situ measurement probe diameter

[0047] In the figure: 1. Z-axis of CNC machine tool; 2. Workpiece spindle; 3. Workpiece; 4. Grinding axis; 5. Workpiece in-position detection device; 6. X-axis of CNC machine tool; 7. Grinding wheel; 8. Support table of workpiece in-position measuring device, 9. Reference surface of workpiece in-position measuring device; 51. Workpiece in-position measuring probe; 52. Workpiece in-position measuring probe; 53. Y-axis fine-tuning knob of workpiece in-position measuring device; 54. X-axis fine-tuning knob of workpiece in-position measuring device; 55. Z-axis adjustment knob of workpiece in-position measuring device; 56. Z-axis fine-tuning knob of workpiece in-position measuring device; 57. Adapter plate of workpiece in-position measuring turntable; 58. Workpiece in-position measuring turntable; 59. Support table of workpiece in-position measuring turntable. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0049] Example

[0050] A three-axis CNC machine tool is used, and the workpiece in-situ measurement probe uses a sapphire probe with a measurement accuracy of 0.01mm and a probe diameter of 6mm. The workpiece to be tested is a standard sphere with a diameter of 25mm and a roundness of no more than 25nm.

[0051] First, adjust the spatial position of the workpiece in-place measurement device, especially the workpiece in-place measurement probe, and calibrate the probe to ensure the relative position of the probe and the workpiece coordinates in the machine tool coordinate system.

[0052] Next, measurement paths are planned in the data processing system based on the workpiece's shape and size. In this example, a 25mm diameter standard sphere is used. The surface of the standard sphere is divided into measurement paths every 15°, with 50 equally spaced measurement points planned for each measurement path. Once planned, the measurement paths are imported into the CNC machine tool's control system.

[0053] Next, the control system controls the three-axis motion of the CNC machine tool, allowing the probe to contact the workpiece surface point by point along the planned measurement path for measurement. During the measurement process, the workpiece in-place measurement probe transmits the measurement data to the data processing system in real time.

[0054] After the measurement is completed, the data processing system processes and analyzes the measurement data and reconstructs the contour model of the workpiece. Based on the measurement data and comparative analysis results, the contour accuracy of the workpiece is evaluated. The measured data is as follows: Figure 6 As shown, there are 24 measurement paths in total, and the spherical morphology is fitted.

[0055] Finally, the processed measurement data and the reconstructed contour model are output to the specified output device for user viewing and analysis. The reconstructed spherical contour and fitting equation are shown below:

[0056] (x-0.000421) 2 +(y-0.001166) 2 +(z-0003098) 2 =15.503274 2 (1)

[0057] The coordinates of the center of the standard sphere are

[0058] x c =0.000421,y c =0.001166,z c =0003098 (2)

[0059] The measured spherical radius is 15.503274mm. Workpiece in-situ measurement probe diameter Therefore, the theoretically measured radius is:

[0060] 252+62=15.5 (3)

[0061] The measurement error is around 3μm, and the evaluation results show that the contour accuracy of the workpiece meets the design requirements.

[0062] Next, the spherical fitting effect is analyzed. The fitting results show that the absolute fitting error is 1.3875μm and the average fitting error is -1.0742e-04μm. The measurement results are accurate and valid.

[0063] In summary, the present invention has significant technical advantages and practical application value, and is of great significance for promoting the development of the manufacturing industry and improving product quality. Furthermore, the technical solution of the present invention can be further optimized and improved according to actual needs to adapt to the requirements of different fields and different workpieces.

Claims

1. A workpiece in-place detection device based on a CNC machine tool, characterized in that: The workpiece in-position detection device is integrated into the CNC machine tool. The workpiece in-position detection device is installed together with the grinding axis on the X-axis of the CNC machine tool, and the measuring axis and the grinding axis are ensured to be at the same height and parallel. The workpiece spindle is installed on the Z-axis of the CNC machine tool, and the three axes of the workpiece spindle, measuring axis and grinding axis are ensured to be coplanar. The workpiece in-situ detection device includes a workpiece in-situ detection component, a control system and a data processing system; The control system is used to control the three-axis motion of the CNC machine tool, and the data processing system is used to receive the measurement data of the workpiece in-situ measurement probe and perform processing and analysis; The workpiece in-place detection component includes a workpiece in-place measurement probe, a workpiece in-place measurement probe, a Y-axis fine-tuning knob of the workpiece in-place measurement device, an X-axis fine-tuning knob of the workpiece in-place measurement device, a Z-axis adjustment knob of the workpiece in-place measurement device, a Z-axis fine-tuning knob of the workpiece in-place measurement device, a workpiece in-place measurement turntable adapter plate, a workpiece in-place measurement turntable, a workpiece in-place measurement turntable support table and a workpiece in-place measurement device reference plane; wherein the workpiece in-place measurement probe is mounted on the workpiece in-place measurement probe, and the workpiece in-place measurement probe is mounted on the reference plane of the workpiece in-place measurement device; the reference plane of the workpiece in-place measurement device is adjusted by the Y-axis fine-tuning knob of the workpiece in-place measurement device, the X-axis fine-tuning knob of the workpiece in-place measurement device, the workpiece in-place measurement turntable adapter plate, the workpiece in-place measurement turntable, the workpiece in-place measurement turntable support table and the workpiece in-place measurement device reference plane; wherein, the workpiece in-place measurement probe is mounted on the workpiece in-place measurement probe, and the workpiece in-place measurement probe is mounted on the reference plane of the workpiece in-place measurement device; the reference plane of the workpiece in-place measurement device is adjusted by the Y-axis fine-tuning knob of the workpiece in-place measurement device, the X-axis fine-tuning knob of the workpiece in-place measurement device, The Z-axis adjustment knob of the measuring device and the Z-axis fine-tuning knob of the workpiece-in-place measuring device are installed on the workpiece-in-place measuring turntable adapter plate. The reference plane of the workpiece-in-place measuring device is adjusted by the Y-axis fine-tuning knob of the workpiece-in-place measuring device, the X-axis fine-tuning knob of the workpiece-in-place measuring device, the Z-axis adjustment knob of the workpiece-in-place measuring device and the Z-axis fine-tuning knob of the workpiece-in-place measuring device; the workpiece-in-place measuring turntable adapter plate is installed on the workpiece-in-place measuring turntable, and the workpiece-in-place measuring turntable can adjust the angle of the workpiece-in-place measuring probe; the workpiece-in-place measuring turntable is installed on the workpiece-in-place measuring turntable adapter plate through the workpiece-in-place measuring turntable support platform, and the workpiece-in-place measuring turntable adapter plate is connected to the X-axis of the CNC machine tool by bolts.

2. A workpiece in-situ detection method based on a CNC machine tool, characterized in that: The steps include: Step 1: Calibration and positioning of the workpiece in-situ detection device First, adjust the spatial position of the workpiece in-place measurement probe to ensure that it is properly connected to the CNC machine tool's control system. The extension length and measurement angle of the workpiece in-place measurement probe are adjusted according to the shape and size of the workpiece. The positioning function of the CNC machine tool ensures that the relative position of the workpiece and the workpiece in-place detection device is accurate and stable. According to the material and measurement accuracy requirements of the workpiece, determine whether the hardness and wear resistance of the workpiece in-situ measurement probe meet the measurement requirements; The control system of the CNC machine tool is preheated and calibrated to ensure measurement accuracy and stability; Step 2: Measurement path planning and probe calibration The measurement path is planned in the data processing system based on the shape, size and measurement accuracy requirements of the workpiece. The measurement path planning ensures that the in-situ measurement probe can cover all key parts of the workpiece surface while avoiding collision with the workpiece. After planning is completed, the measurement path is imported into the control system of the CNC machine tool; The CNC machine tool's three-axis motion moves the workpiece's in-situ measurement probe along a predetermined measurement path, while simultaneously recording the actual coordinates of the workpiece's in-situ measurement probe at each position. The actual coordinates are compared with the theoretical coordinates, and the probe's extension length and measurement angle are adjusted until the deviation between the actual and theoretical coordinates is within the allowable range. Step 3: Point-by-point measurement and data collection After the workpiece in-situ measurement probe is calibrated, the control system controls the CNC machine tool to perform three-axis motion, so that the workpiece in-situ measurement probe contacts the workpiece surface point by point along the planned measurement path for measurement; During the measurement process, the workpiece in-situ measurement probe transmits the measurement data to the data processing system in real time; After receiving the measurement data, the data processing system performs preliminary processing and storage for subsequent analysis and processing; Step 4: Data processing and contour reconstruction The data processing system processes and analyzes the received measurement data. First, it filters and removes noise to improve the accuracy and reliability of the data. Then, it reconstructs the contour model of the workpiece based on the measurement data. Continuous contour curves or surfaces are generated based on the coordinate information of the measurement points. Step 5: Output and evaluation of test results The processed measurement data and reconstructed contour model are output to the designated output device or storage medium for user viewing and analysis; at the same time, the contour accuracy of the workpiece is evaluated based on the measurement data and comparative analysis results.

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