Workpiece in-place detection device and method based on numerical control machine tool

Abstract

The invention belongs to the technical field of workpiece detection, and discloses a workpiece in-place detection device and method based on a numerical control machine tool, the workpiece in-place detection device is integrated on the numerical control machine tool, the workpiece in-place detection device and a grinding shaft are installed on the X axis of the numerical control machine tool together, and it is guaranteed that a measuring shaft and the grinding shaft are equal in height and parallel; the workpiece spindle is installed on the Z axis of the numerical control machine tool, and it is guaranteed that the workpiece spindle, the measuring shaft and the grinding shaft are coplanar. Point-by-point measurement of the surface of the workpiece is achieved through the workpiece in-place detection device on the numerical control machine tool in combination with three-axis movement of the numerical control machine tool, and therefore contour information of the workpiece is accurately obtained. The method has the advantages of high measurement precision, high measurement speed, simplicity and convenience in operation and the like, and is suitable for detecting workpieces with various shapes and sizes. Through verification of specific embodiments, the technical scheme of the invention achieves a good effect in practical application, and provides an efficient and accurate means for online monitoring and quality control of workpiece processing quality.

Description

Technical Field

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

[0002] In modern manufacturing, the accuracy of workpiece contour is one of the important criteria for measuring product quality. Traditional workpiece contour detection methods mostly use offline measurement methods, that is, the workpiece is removed from the CNC machine tool and inspected by equipment such as a coordinate measuring machine. However, this method is not only time-consuming and labor-intensive, but also easily introduces secondary errors, affecting measurement accuracy.

[0003] Among various measuring instruments, coordinate measuring machines equipped with trigger / scanning probes are still the most widely used instruments in the industrial field, especially when measuring large-scale high-precision free-form surfaces. Ren et al. showed in their study “ACurveNetwork Sampling Strategy for Measurement of Freeform Surfaces on CoordinateMeasuring Machines” that the measurement process often hopes to use the least samples to achieve a given sampling accuracy level in order to save time costs and improve work efficiency. On the other hand, SDPhillips et al. showed in “The estimation of measurement uncertainty of small circular features measured by coordinatemeasuring machines” that insufficient sampling may cause deviations in the measurement of machined surface shape errors and may become the main factor in measurement uncertainty. R.Wilhelm et al.’s study “Task specific uncertainty incoordinate measurement” also found that this becomes more stringent when it comes to the accuracy level required for high-precision free-form surfaces from micron to sub-micron levels.

[0004] Although there have been some attempts at in-situ detection technologies, most of these technologies have limitations. The review "Review on grinding wheel wear measurement methods" shows that in-situ detection can be achieved by traditional methods such as copying, acoustic emission, projection or eddy current methods, but these methods either have low detection accuracy or are only applicable to specific types of workpieces and tools, and cannot meet the needs of complex contours and high-precision detection. Wang et al. showed in "On-Machine Precision Form Truing and In-Situ Measurement of Resin-Bonded Spherical Diamond Wheel" that contour detection can be performed using non-contact methods such as laser displacement sensors, but these methods require a complex drive mechanism to be set between the sensor and the workpiece, which increases the complexity of the detection device and is easily affected by the surface roughness of the workpiece, resulting in a decrease in detection accuracy. Yin et al. also showed in "Dependant Gaussian processes regression for intelligent sampling of freeform and structured surfaces" that the workpiece surface is uniformly or randomly sampled and measured without considering geometric features. When the data acquisition cost is high, the efficiency of blind sampling measurement is relatively low, and there is an important trade-off between sampling accuracy and detection 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 on-site intelligent detection device and method for workpiece contour, which realizes point-by-point measurement of the workpiece surface through a single-point probe on a CNC machine tool in combination with the three-axis motion of the CNC machine tool, 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 based on a numerically controlled machine tool comprises a workpiece in-position detection device integrated on the numerically controlled machine tool. The workpiece in-position detection device is installed on the X-axis of the numerically controlled machine tool together with a grinding axis, and ensures that the measuring axis and the grinding axis are at 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.

[0008] Furthermore, the workpiece in-situ monitoring device comprises 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 the measurement data of the single-point probe and process and analyze it.

[0009] Furthermore, the workpiece in-place detection component includes a workpiece in-place measurement probe, a workpiece in-place measurement probe, 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 plane. 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 workpiece in-place measurement device reference plane.

[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 installed on the workpiece in-place measurement turntable, and the workpiece in-place measurement turntable can adjust the workpiece in-place measurement probe angle. The workpiece in-place measurement turntable is installed on the workpiece in-place measurement turntable adapter plate through the workpiece in-place measurement turntable support platform, and the workpiece in-place measurement turntable adapter plate is connected to the X-axis of the CNC machine tool by bolts.

[0012] A workpiece in-situ detection method based on a CNC machine tool includes the following five steps:

[0013] Step 1: Device calibration and positioning

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

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

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

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

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

[0019] According to the shape and size of the workpiece, as well as the measurement accuracy requirements, the measurement path planning is carried out in the data processing system. The measurement path planning should ensure that the probe can cover all key parts of the workpiece surface while avoiding collision with the workpiece. After the planning is completed, the measurement path is imported into the control system of the CNC machine tool.

[0020] Through the three-axis motion of the CNC machine tool, the probe is moved along the predetermined path, and the actual coordinates of the probe at each position are recorded. The actual coordinates are compared with the theoretical coordinates, and the extension length and measurement angle of the probe are adjusted until the deviation between the actual coordinates and the 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 CNC machine tool to move along three axes, so that the probe contacts the workpiece surface point by point for measurement according to the planned measurement path. During the measurement process, the single-point 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.

[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 the integrity and accuracy of the data.

[0027] Step 4: Data processing and contour reconstruction

[0028] The data processing system processes and analyzes the received measurement data. First, the measurement data is filtered and denoised to improve the accuracy and reliability of the data. Then, the contour model of the workpiece is reconstructed based on the measurement data. Contour reconstruction can use mathematical methods such as interpolation algorithms and fitting algorithms to generate continuous contour curves or surfaces based on the coordinate information of the measurement points.

[0029] During data processing and contour reconstruction, the following points should 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: Test result output and evaluation

[0034] The processed measurement data and reconstructed contour model are output to the specified output device or storage medium for users to view and analyze. At the same time, the contour accuracy of the workpiece 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] In the process of outputting and evaluating the test results, the following points should be noted:

[0036] The choice 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 numerically controlled machine tool. Through 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. The method has the advantages of high measurement accuracy, fast measurement speed, and simple operation, and is suitable for workpiece detection of various shapes and sizes. Through verification of specific embodiments, the technical solution of the present invention has achieved good results in practical applications, and provides an efficient and accurate means for online monitoring and quality control of workpiece processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0042] Figure 2 It 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-situ 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.

[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 is 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. spindle of workpiece; 3. workpiece; 4. grinding axis; 5. workpiece in-place detection device; 6. X-axis of CNC machine tool; 7. grinding wheel; 8. support table of workpiece in-place measuring device, 9. reference surface of workpiece in-place measuring device; 51. workpiece in-place measuring probe; 52. workpiece in-place measuring probe; 53. Y-axis fine-tuning knob of workpiece in-place measuring device; 54. X-axis fine-tuning knob of workpiece in-place measuring device; 55. Z-axis adjustment knob of workpiece in-place measuring device; 56. Z-axis fine-tuning knob of workpiece in-place measuring device; 57. adapter plate of workpiece in-place measuring turntable; 58. workpiece in-place measuring turntable; 59. support table of workpiece in-place 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 ball with a diameter of 25mm and a roundness of no more than 25nm.

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

[0052] Then, according to the shape and size of the workpiece, the measurement path is planned in the data processing system. In this embodiment, a standard ball with a diameter of 25 mm is selected, and the surface of the standard ball is divided into a measurement path every 15°, and 50 measurement points are equidistantly planned for each measurement path. After the planning is completed, the measurement path is imported into the control system of the CNC machine tool.

[0053] Next, the control system controls the CNC machine tool to perform three-axis motion, so that the probe contacts the workpiece surface point by point for measurement according to the planned measurement path. During the measurement process, the workpiece in-situ 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 users to view and analyze. 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 15.503274 mm. Workpiece in-situ measurement probe diameter Therefore, the theoretically measured radius is:

[0060] 252+62=15.5 (3)

[0061] The measurement error is about 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. At the same time, the technical solution of the present invention can be further optimized and improved according to actual needs to meet the needs of different fields and different workpieces.

Claims

1. A workpiece in-situ detection device based on a CNC machine tool, characterized in that: The workpiece in-position detection device is integrated on a 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 workpiece spindle, the measuring axis and the grinding axis are ensured to be coplanar. The workpiece in-situ detection device comprises 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 process and analyze it; The workpiece in-place detection component comprises a workpiece in-place measurement probe, a workpiece in-place measurement probe, a Y-axis fine-tuning knob of a workpiece in-place measurement device, an X-axis fine-tuning knob of a workpiece in-place measurement device, a Z-axis adjustment knob of a workpiece in-place measurement device, a Z-axis fine-tuning knob of a workpiece in-place measurement device, an adapter plate of a workpiece in-place measurement turntable, a workpiece in-place measurement turntable support table and a reference plane of a workpiece in-place measurement device; 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, and the workpiece in-place measurement turntable support table. 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 to adjust the plane space distance; 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-situ measurement probe to ensure that the workpiece in-situ measurement probe is properly connected to the control system of the CNC machine tool, and the extension length and measurement angle of the workpiece in-situ measurement probe are adjusted according to the shape and size of the workpiece; through the positioning function of the CNC machine tool, ensure that the relative position of the workpiece and the workpiece in-situ 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 According to the shape, size and measurement accuracy requirements of the workpiece, measurement path planning is carried out in the data processing system; measurement path planning ensures that the workpiece 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; Through the three-axis motion of the CNC machine tool, the workpiece in-situ measurement probe is moved according to the predetermined measurement path, and the actual coordinates of the workpiece in-situ measurement probe at each position are recorded at the same time; the actual coordinates are compared with the theoretical coordinates, and the extension length and measurement angle of the workpiece in-situ measurement probe are adjusted until the deviation between the actual coordinates and the 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 for measurement according to the planned measurement path; 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, the measurement data is filtered and denoised to improve the accuracy and reliability of the data; then, the contour model of the workpiece is reconstructed based on the measurement data; a continuous contour curve or surface is generated based on the coordinate information of the measurement points; Step 5: Test result output and evaluation The processed measurement data and reconstructed contour model are output to the specified output device or storage medium for users to view and analyze; at the same time, the contour accuracy of the workpiece is evaluated based on the measurement data and comparative analysis results.

Images