A method and system for testing and benchmarking miter saws

Abstract

The present application is a method and system for testing and benchmarking a miter saw and numerical calculations, which belongs to the field of cutting tool detection. In view of the problem that the existing technology can no longer meet the strict requirements for cutting accuracy in industrial production, a method for testing and benchmarking a miter saw and numerical calculations is provided, including: constructing a test data processing model, using the constructed test data processing model to perform static testing of the miter saw to obtain static test data; using the constructed test data processing model to perform dynamic testing of the miter saw to obtain dynamic simulation data; obtaining comprehensive miter saw physical test data; constructing a miter saw finite element analysis model to obtain analysis data; benchmarking the miter saw physical test data and analysis data to determine whether the two meet the benchmarking conditions, and if not, returning to modify the parameters of the miter saw finite element analysis model until the benchmarking conditions are met. The present application can improve the accuracy of the test data and can also predict the offset of the miter saw.

Description

Technical Field

[0001] The invention belongs to the field of cutting tool detection, and in particular relates to a method and system for testing and numerically calculating a miter saw. Background Art

[0002] In the current industrial manufacturing field, miter saws are a key power tool, and their precision in cutting operations is crucial. However, miter saws often encounter problems with substandard cutting accuracy during actual operation, mainly because the saw blade cannot accurately maintain the set angle with the work surface during cutting, resulting in a deviation in the cutting result. This angle deviation not only affects the processing quality of the product, but may also lead to material waste and error accumulation in the subsequent assembly process.

[0003] Faced with this challenge, engineers usually use physical tests to measure the offset of the miter saw blade during operation and formulate improvement measures accordingly. Currently, a single digital dial indicator is usually used in conjunction with a parallelism detection instrument to measure the fluctuating offset distance of the saw blade during movement. However, the defects of this method are mainly reflected in:

[0004] 1. Due to the limitations of the test tools, it is impossible to obtain ideal results when testing data:

[0005] Limitations of data acquisition: The digital dial indicator can only provide a maximum offset distance, but cannot record the continuous offset of the saw blade during the entire movement process, which means that it is impossible to fully understand the dynamic stability and accuracy of the saw blade, making it difficult to accurately evaluate the performance of the saw blade.

[0006] Insufficient test auxiliary devices: Due to the lack of well-designed test auxiliary devices, the digital display is difficult to effectively capture the extreme deviation of the saw blade during each test. The mobility of the saw blade during the test increases the difficulty of measurement, making data acquisition unstable and affecting the accuracy and reliability of the test results.

[0007] 2. Due to the single data processing method, the display and prediction effect of saw blade deflection is insufficient:

[0008] Lack of detailed breakdown: The existing methods do not break down the offset angle in detail and only provide the offset distance in a single direction. Such data is difficult to accurately reflect the deflection angle of the saw blade in complex movements, making it impossible to accurately calibrate the accuracy of the saw blade.

[0009] Insufficient prediction and detection capabilities: Existing methods have difficulty in effectively predicting and detecting the main problem components and error sources of product equipment. This is crucial for quickly locating problems and making targeted improvements, but traditional testing methods are clearly insufficient in this regard.

[0010] In summary, the existing testing methods for miter saws can no longer meet the strict requirements for cutting accuracy in industrial production. Engineers need a new testing method that can provide continuous and comprehensive saw blade offset data to finely split the deflection angle and have high-precision measurement capabilities to ensure the cutting accuracy of the miter saw during operation and meet the high standards of modern manufacturing. Summary of the invention

[0011] In view of the problem that the existing technology can no longer meet the strict requirements for cutting accuracy in industrial production, the present application provides a method and system for testing and numerically calculating a miter saw. By setting a static test model and a dynamic test model, continuous and comprehensive saw blade offset and deflection data are provided. By setting a miter saw finite element analysis model, the offset and deflection errors of the saw blade during the cutting process can be effectively predicted and analyzed, thereby ensuring the cutting accuracy of the miter saw during operation.

[0012] The technical solution adopted by the present invention is as follows: a method for testing and numerically calculating a miter saw comprises the following steps:

[0013] S1, constructing a test data processing model: using two-point eddy current induction electrical signals to collect displacement data about the miter saw, and converting the data of the two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around the coordinate axis;

[0014] S2, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data;

[0015] S3, using the constructed test data processing model to perform a dynamic test of the miter saw to obtain dynamic test data;

[0016] S4, supplementing the static data with the dynamic data to obtain comprehensive physical test data of the miter saw, so as to obtain continuous and relatively accurate test data;

[0017] S5, constructing a finite element analysis model of the miter saw, including pre-processing settings of boundary constraints and load application of the digital three-dimensional model of the miter saw in accordance with the physical test conditions, and obtaining finite element analysis result data through finite element solution;

[0018] S6, benchmarking the physical test data of the miter saw and the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, returning to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met to improve the reliability of the finite element analysis results.

[0019] The original test method does not consider the detailed deflection angle, and only provides the deflection distance in a single direction. In order to make the collected data more accurately reflect the deflection angle of the saw blade in complex motion, a two-point eddy current signal acquisition method is used here to complete the deflection deflection at each angle with the minimum test cost. This processing method can improve the accuracy of the test data.

[0020] This application can improve the accuracy of test data and predict the offset of the miter saw. It not only uses a high-precision measurement method, but also combines numerical calculation results for benchmarking to ensure the accuracy and reliability of the test method. In this way, the angular offset problem of the miter saw during operation can be more accurately identified and its structure can be continuously improved in the future.

[0021] Furthermore, constructing the test data processing model includes the following steps:

[0022] Using two-point eddy current induction electric signals to obtain distance data about the miter saw;

[0023] Construct the X-axis, Y-axis and Z-axis directions in the space and determine the corresponding displacement data in each axis: set the direction parallel to the standard gravity direction of the detection point as the Z-axis, set the direction perpendicular to the standard gravity direction and along the slide bar of the miter saw as the X-axis, and determine the Y-axis of the coordinate system based on the directions of the X-axis and Z-axis according to the right-hand rule;

[0024] Construct a method for calculating the deflection angle of the coordinate system rotating around the X-axis, Y-axis and Z-axis: convert the displacement offset components of the two test points in the Z-axis direction on the ZY plane into the deflection angle around the X-axis; convert the displacement offset components of the two points in the X-axis direction on the XY plane into the deflection angle around the Z axis; and convert the displacement offset components of the two points in the X-axis direction on the XZ plane into the deflection angle around the Y axis.

[0025] In view of the problem that when obtaining the offset distance of the miter saw through the digital display dial indicator, only an offset limit distance can be provided, and the continuous offset of the saw blade during the entire movement process cannot be recorded, the electrical signal data acquisition method is first introduced here to obtain comprehensive and continuous collection data, in preparation for subsequent data processing and analysis. In this application, the eddy current induction method of collecting electrical signals is used to replace the mechanical digital display dial indicator to accurately measure the displacement change of the miter saw equipment under actual operation. In view of the problem that the existing method does not consider the detailed decomposition of the offset angle in the original test process and only provides a single direction offset distance, in order to make the collected data more accurately reflect the deflection angle of the saw blade in complex motion, a two-point eddy current signal acquisition method is adopted here. The reason for adopting the two-point method is that this method can complete the decomposition of each angle deflection here with the minimum testing cost. Specifically, the measuring point is decomposed into displacement deflection around the X-axis, around the Y-axis and around the Z-axis by vertically (determined as the z-axis) and horizontally (determined as the X-axis) (the definition of the axial direction is shown in the coordinate system on the upper right side of the figure below).

[0026] Furthermore, the specific method of using two-point eddy current induction electrical signals to obtain displacement data about the miter saw is as follows:

[0027] The real-time electrical signal is collected by eddy current, and the frequency and distribution of the electrical signal (sine harmonics of different frequencies) are obtained by using the fast Fourier transform (FFT) algorithm; the formula for Fourier transform is:

[0028]

[0029] in, is the time domain signal, is its Fourier transform, j is the imaginary unit, is the angular frequency;

[0030] Based on the frequency and distribution of the electrical signal (sine harmonics of different frequencies), the phase is extracted according to the phase demodulation method; the frequency component and phase information of the signal can be obtained through Fourier transform. The phase demodulation technology relies on the analysis of this phase information. The formula for phase extraction can be expressed as:

[0031]

[0032] in, is the frequency component The phase angle at , arg represents the phase of the complex number.

[0033] According to the phase changes at different time points, the extreme value and difference of displacement are calculated, and the displacement change The calculation formula is:

[0034]

[0035] in, and At time t 1 and t 2 The phase of It is the frequency component related to the displacement change. Based on this, the extreme value and difference of the displacement are obtained, thereby realizing the accurate measurement of the displacement deflection of the miter saw.

[0036] The working mechanism of collecting real-time electrical signals through eddy current is based on the eddy current effect. It uses high-frequency current signals to be transmitted to the probe end through the cable and generate an alternating magnetic field around it. If there is no metal conductor material close to the magnetic field range, then all the energy emitted into this range will be released. However, if there is a metal conductor material close to the probe end, the alternating magnetic field will generate an eddy current field on the surface of the conductor, and the eddy current field will also generate an alternating magnetic field in the opposite direction. This interaction will change the amplitude and phase of the high-frequency current in the coil of the probe head, that is, change the effective impedance of the coil. By monitoring this impedance change, the corresponding current signal can be obtained, and then the output electrical signal is Fourier transformed. The measurement signal can be understood as a set of sinusoidal harmonics of different frequencies. The different frequency components and distribution contained in the signal can be quickly analyzed through the fast Fourier transform (FFT) algorithm.

[0037] By means of the above method, the accuracy of measuring the displacement deflection of the miter saw is improved.

[0038] Taking the X-axis as an example, the calculation formula for the deflection angle of the miter saw blade around the X-axis is:

[0039]

[0040] Specifically, is the deflection angle of the miter saw blade around the x-axis, and is the axial displacement.

[0041] Furthermore, the static test process is as follows:

[0042] S2.1, construct a static test model: use a saw blade replacement to increase the effective detection distance when the saw blade moves. The saw blade replacement is consistent with the center fixing hole and diameter position and size of the original saw blade; set the parameters of the static test model, including the operator's height, weight, and arm extension angle;

[0043] S2.2, based on the constructed test data processing model, test and process the data under different static tests, obtain the offset and deflection angle of the miter saw under different working conditions of the static test, and calculate the center of gravity position of the operator using the moment synthesis method;

[0044] S2.3, obtain the center of gravity change curves under different static tests, and determine whether the change in accuracy is caused by the center of gravity shift by describing the influence of the center of gravity shift on the accuracy of the miter saw.

[0045] During the static testing phase, the goal is to obtain the overall deflection caused by the movement of the saw head with the saw blade stationary.

[0046] The probe ends required for data collection via eddy current electrical signals are fixed to the scaffold and maintained in the corresponding axial directions of the Y and Z axes as specified in the test plan. Since the saw blade of the miter saw is circular and serrated, this poses a challenge to measurement because such a shape makes it difficult to form effective measurement conditions. Due to the lack of a well-designed test auxiliary device, the probe that collects data during each test is difficult to effectively capture the offset during the complete movement of the saw blade. Not only does the mobility of the saw blade during the test increase the difficulty of measurement, making data acquisition unstable, but because of its shape, the probe cannot be effectively and completely measured when positioning the saw blade, which affects the accuracy and reliability of the test results.

[0047] In order to ensure the stability of the test and the accuracy of the measured offset, the entire measurement environment must remain stable and reliable. The probe ends required for collecting data through eddy current electrical signals are fixed on the scaffolding and maintain the corresponding axial directions in the Y and Z axes specified in the test plan.

[0048] The circular serrations of the miter saw blades present a challenge as the shape makes it difficult to create effective measurement conditions. Due to the lack of a properly designed test aid, the probe that collects data during each test is unable to effectively capture the deflection of the saw blade during its complete motion. Not only does the mobility of the saw blade during the test make the measurement more difficult, making data acquisition unstable, but its shape also makes it difficult to effectively and completely measure the movement of the saw blade while the probe is positioned, which affects the accuracy and reliability of the test results. The original saw blade was replaced during the static test to ensure that the eddy current sensor can effectively detect the entire movement. The measurement conditions for the eddy current probe electrical signal acquisition require the detection distance between the probe and the metal to be maintained at approximately 20mm, so the use of this replacement part is necessary.

[0049] Furthermore, the static test includes a left-hand pull test, a left-hand push test, a right-hand pull test, a right-hand push test, a double-hand pull test, a double-hand push test, and a double-hand (motor support) test. When performing these tests, a test data processing model is used to collect and process data, collect single-number data and perform mean processing to obtain corresponding test data.

[0050] The purpose of these tests is to examine the influence of force direction on deflection and the influence of the center of gravity of the human body on the working state.

[0051] Furthermore, the formula for calculating the center of gravity coordinates includes:

[0052]

[0053] in, is the mass of each body part, and are the coordinates of each part, and M is the total mass. Next, by comparing the changes in the center of gravity when the left and right hands are operated, the effect on the stability of the miter saw operation is analyzed.

[0054] In the static test phase, the goal is to simulate the overall deflection caused by the movement of the saw head when the saw blade is stationary. In order to ensure the stability of the test and the accuracy of the measured deflection, the entire measurement environment must remain stable and reliable.

[0055] Furthermore, the dynamic test process is as follows:

[0056] S3.1, build a dynamic test model: build a dynamic test model: set key points and patch processing at the key points, and use external clamps to fix the test equipment, and set the specific working conditions of the miter saw test, including the cutting angle, saw blade material, and the length and thickness of the cut wood; through the test key point data, the rigid deformation degree of the overall structure of the saw head can be obtained;

[0057] S3.2, based on the constructed test data processing model, the rigid deformation degree of the overall structure of the miter saw head is obtained by testing the key point data, and the dynamic offset and deflection angle of the miter saw under different variables are obtained.

[0058] When constructing the dynamic test model, the measurement points corresponding to the simulation key probe points were selected for patch processing to correspond to the probe effect, and the corresponding fixed scaffolding was set for the patches under each set of measurement conditions. In addition, horizontal metal patches were set at the top of the saw head and the top of the back seat to test the rigid deformation of the overall structure of the saw head. When constructing the dynamic test model, the cutting angle of the miter saw, the material of the saw blade, and the length and thickness of the cut wood were grouped as variables for testing to comprehensively evaluate the offset under different conditions.

[0059] Furthermore, constructing the finite element analysis model of the miter saw specifically includes:

[0060] S5.1, determine the main structural parts that affect the overall strength, and build a digital three-dimensional model of the miter saw based on the finite element analysis model;

[0061] S5.2, determining the type of mesh setting in the finite element analysis model and using an unstructured mesh generation algorithm to automatically adjust the mesh size according to the size change of the digitized three-dimensional model;

[0062] S5.3, input the pre-processing settings of boundary constraints and load application of the benchmark physical test conditions, and obtain the finite element analysis result data through finite element solution.

[0063] Furthermore, the main structural parts that affect the overall strength include a saw head, a sliding rod, a turntable and a base, wherein the saw head includes a motor, a handle, a housing, a saw blade protective shell and a saw blade, the front end of the sliding rod is connected to the saw head, the rear end of the sliding rod is connected to the sliding rod rear seat, and is connected to the rocker arm through a sliding bearing, and the turntable is connected to the base and the rocker arm.

[0064] When constructing the finite element analysis model of the miter saw, in addition to model simplification, the reasonable form of each contact pair is defined, and the reasonable mesh division is completed. When constructing the finite element analysis model of the miter saw, the core of data processing lies in the logic of mesh division, that is, automatically adjusting the mesh type and size according to the change of the volume of the structural part. This process follows the principle of adaptive mesh technology, and its basic idea is to dynamically change the mesh structure in the calculation area to adapt to the needs of physical quantity changes. In areas where physical quantities change dramatically, such as stress concentration areas, the mesh is automatically refined to improve the calculation accuracy; while in areas where the changes are gentle, the mesh is relatively sparse to maintain calculation efficiency. Specifically, mesh division can be controlled by the following formula:

[0065]

[0066] Where h is the grid size, h 0 is the initial grid size, e target is the target error, e current is the current error, and n is the order of mesh refinement. By dynamically adjusting the mesh size, you can ensure more accurate simulation results in critical areas while maintaining a reasonable computational load in other areas.

[0067] Furthermore, unstructured grid generation algorithms, including the Delaunay method and the Advancing-Front method (wavefront method), are used to ensure that the grid properties can be dynamically adjusted during the generation process, with good controllability and good quality of the final generated grid.

[0068] The Delaunay triangulation used is a triangulation method based on the Delaunay condition, that is, for any triangle in the triangulation, its circumscribed circle should not contain any other points. This method can ensure that the generated triangles are as close to equilateral triangles as possible, thereby improving the quality of the mesh.

[0069] The Advancing-Front method is a layer-by-layer mesh generation method that starts from an initial boundary and gradually expands inward to form new mesh units.

[0070] Furthermore, the benchmarking conditions are as follows: the static data and dynamic data corresponding to each test point are compared with the data of the corresponding position in the finite element analysis results, and whether they are benchmarked is determined based on the absolute value and trend of the deformation.

[0071] The benchmarking process involves comparing the analytical values ​​obtained from the finite element analysis model of the miter saw with the test data to ensure the accuracy and effectiveness of the simulation. In addition to the connection relationship between the above-mentioned major components corresponding to the actual situation, data benchmarking also requires the benchmarking and design of the numerical calculation probe position and the actual test position. Some probe points are set on the miter saw equipment, which are the three key deformation nodes of the horizontal plane of the slide bar rear seat, the top of the saw head and the horizontal plane of the connector.

[0072] A system for testing and numerically calculating a miter saw, comprising:

[0073] The data processing module constructs a test data processing model, uses two-point eddy current induction electrical signals to collect displacement data about the miter saw, and converts the data of the two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around the coordinate axis;

[0074] A static test module, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data;

[0075] A dynamic test module uses the constructed test data processing model to perform a dynamic test of the miter saw to obtain dynamic test data;

[0076] The benchmarking module combines and analyzes static and dynamic data to obtain comprehensive physical test data of miter saws;

[0077] Prediction analysis module, builds the finite element analysis model of the miter saw and obtains the finite element analysis result data;

[0078] The correction module compares the physical test data of the miter saw with the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, it returns to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met.

[0079] The beneficial effects of the present invention are as follows: The present application is a method and system for testing and benchmarking miter saws, which improves the accuracy of detection data by constructing a test data processing model, obtains relatively accurate and continuous miter saw test data by constructing a static test model and a dynamic test model, and predicts the cutting deviation of the miter saw by establishing a miter saw finite element analysis model to ensure cutting accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 A flow chart of the method for testing and numerically calculating the benchmarking of a miter saw according to Example 1;

[0081] Figure 2 A flowchart of obtaining physical test data of a miter saw according to Example 1;

[0082] Figure 3 This is a schematic diagram of the saw blade replacement structure;

[0083] Figure 4 This is a schematic diagram comparing the saw blade replacement and the original saw blade;

[0084] Figure 5 Schematic diagram of data processing for testing data processing model. DETAILED DESCRIPTION

[0085] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0086] Example 1

[0087] A method for testing and benchmarking miter saws, the flow chart is as follows Figure 1 As shown, the following steps are included:

[0088] S1, build a test data processing model, the flow chart is as follows Figure 2 As shown: using two-point eddy current induction electrical signals to collect displacement data about a miter saw, and converting the data of two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around a coordinate axis; including the following steps:

[0089] The distance data of the miter saw is obtained by using two-point eddy current induction electrical signals; the specific method is as follows:

[0090] The real-time electrical signal is collected by eddy current, and the frequency and distribution of the electrical signal (sine harmonics of different frequencies) are obtained by using the fast Fourier transform (FFT) algorithm; the formula for Fourier transform is:

[0091]

[0092] in, is the time domain signal, is its Fourier transform, j is the imaginary unit, is the angular frequency;

[0093] Based on the frequency and distribution of the electrical signal (sine harmonics of different frequencies), the phase is extracted according to the phase demodulation method; the frequency component and phase information of the signal can be obtained through Fourier transform. The phase demodulation technology relies on the analysis of this phase information. The formula for phase extraction can be expressed as:

[0094]

[0095] in, is the frequency component The phase angle at , arg represents the phase of the complex number.

[0096] According to the phase changes at different time points, the extreme value and difference of displacement are calculated, and the displacement change The calculation formula is:

[0097]

[0098] in, and At time t 1 and t 2 The phase of It is the frequency component related to the displacement change. Based on this, the extreme value and difference of the displacement are obtained, thereby realizing the accurate measurement of the displacement deflection of the miter saw.

[0099] Construct the X-axis, Y-axis and Z-axis directions in the space and determine the corresponding displacement data in each axis: set the direction parallel to the standard gravity direction of the detection point as the Z-axis, set the direction perpendicular to the standard gravity direction and along the slide bar of the miter saw as the X-axis, and determine the Y-axis of the coordinate system based on the directions of the X-axis and Z-axis according to the right-hand rule;

[0100] Construct the calculation method of the deflection angle of the coordinate system rotating around the X-axis, Y-axis and Z-axis: convert the displacement offset components of the two test points in the Z-axis direction on the ZY plane into the deflection angle around the X-axis; convert the displacement offset components of the two points in the X-axis direction on the XY plane into the deflection angle around the Z axis; convert the displacement offset components of the two points in the X-axis direction on the XZ plane into the deflection angle around the Y axis. Taking the X-axis as an example, the calculation formula for the deflection angle is:

[0101]

[0102] Specifically, is the deflection angle of the miter saw blade around the x-axis, and is the axial displacement.

[0103] S2, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data; the static test process is as follows:

[0104] S2.1, build a static test model: use a saw blade replacement to increase the effective detection distance when the saw blade moves. The saw blade replacement is consistent with the center fixing hole and diameter position and size of the original saw blade; set the parameters of the static test model, which include the operator's height, weight, and arm extension angle; in order to solve this problem, a measurement replacement is used here, that is, a saw blade replacement with a long measurement distance is used to increase the effective detection distance when the saw blade moves. Figure 3 and Figure 4 As shown, taking an eight-inch saw blade with a diameter of 210 mm (i.e., the diameter H1 shown in the figure) as an example, the size of the center fixing hole (diameter H2) of the original saw blade is restored during the replacement design process to maintain a reasonable assembly relationship with the miter saw.

[0105] To reserve enough detection space, 1 / 2 radius (i.e. H3) below the bottom of the saw blade. ) to 400mm (i.e., length H4) to meet the overall cutting saw distance. Specifically, the original saw blade is replaced in the static test phase to ensure that the eddy current sensor can effectively detect during the entire movement process. The measurement conditions for eddy current probe electrical signal acquisition require that the detection distance between the probe and the metal be maintained at approximately 20mm, so the use of this replacement part is necessary.

[0106] In order to ensure the feasibility of processing, the tangential position of the saw blade is extended without affecting the effective measurement space of the saw blade replacement. The actual processing diagram is shown in the figure.

[0107] S2.2, based on the constructed test data processing model, test and process the data under different static tests, obtain the offset and deflection angle of the miter saw under different working conditions of the static test, and use the torque synthesis method to calculate the center of gravity position of the operator; the static test includes left-hand pull test, left-hand push test, right-hand pull test, right-hand push test, two-hand pull test, two-hand push test and two-hand (motor support) test. When doing these tests, the test data processing model is used to collect and process the data, collect single-number data and perform mean processing to obtain the corresponding test data.

[0108] The formulas for calculating the barycentric coordinates include:

[0109]

[0110] in, is the mass of each body part, and are the coordinates of each part, and M is the total mass. Next, by comparing the changes in the center of gravity when the left and right hands are operated, the effect on the stability of the miter saw operation is analyzed.

[0111] S2.3, obtain the center of gravity change curves under different static tests, and determine whether the change in accuracy is caused by the center of gravity shift by describing the influence of the center of gravity shift on the accuracy of the miter saw.

[0112] S3, using the constructed test data processing model to perform dynamic testing of the miter saw to obtain dynamic test data; the process is:

[0113] S3.1, build a dynamic test model: set key points and patch processing at the key points, and use external fixtures to fix the test equipment, and set the specific working conditions of the miter saw test, including the cutting angle, saw blade material, and the variables of the length and thickness of the cut wood;

[0114] S3.2, based on the constructed test data processing model, the rigid deformation degree of the overall structure of the miter saw head is obtained by testing the key point data, and the dynamic offset and deflection angle of the miter saw under different variables are obtained.

[0115] S4, supplementing the static data with the dynamic data to obtain comprehensive physical test data of the miter saw, so as to obtain continuous and relatively accurate test data;

[0116] Taking the horizontal deflection of 90° as an example, Table 1 is a summary of the static test data and the dynamic test data. The schematic diagram of the test data processing model is as follows: Figure 5 When the existing technology is used for testing, only absolute displacement data can be obtained. It can be seen from this that the solution of the present application can obtain more comprehensive and accurate data.

[0117] Table 1

[0118]

[0119] S5, constructing a finite element analysis model of the miter saw, including pre-processing settings of boundary constraints and load application of the digital three-dimensional model of the miter saw in accordance with the physical test conditions, and obtaining finite element analysis result data through finite element solution; specifically including:

[0120] S5.1, determine the main structural parts that affect the overall strength, and construct a digital three-dimensional model of the miter saw based on the finite element analysis model; the main structural parts that affect the overall strength include a saw head, a slide bar, a turntable and a base, wherein the saw head includes a motor, a handle, a housing, a saw blade protective shell and a saw blade, the front end of the slide bar is connected to the saw head, the rear end of the slide bar is connected to the slide bar rear seat, and is connected to the rocker arm through a sliding bearing, and the turntable is connected to the base and the rocker arm.

[0121] S5.2, determine the type of mesh setting in the finite element analysis model, and use an unstructured mesh generation algorithm to automatically adjust the mesh size according to the size change of the digital three-dimensional model; the logic of mesh division is to automatically adjust the mesh type and size according to the volume of the structural part. The overall mesh scale and mesh quality of the model should be appropriate. The mesh should be encrypted in the key verification area, and the mesh size can be appropriately increased in the non-important area. It is recommended to use high-order units to divide the model; for local areas with high stress states and large stress gradient changes, the mesh should be subdivided to pursue high-quality meshes. Some thin-walled and rounded corner features are divided into at least three layers of units. In this process, unstructured mesh generation algorithms, including the Delaunay method and the Advancing-Front method (wavefront method), are used to ensure that the mesh properties can be dynamically adjusted during the generation process, with good controllability and good quality of the final generated mesh.

[0122] The Delaunay triangulation used is a triangulation method based on the Delaunay condition, that is, for any triangle in the triangulation, its circumscribed circle should not contain any other points. This method can ensure that the generated triangle is as close to an equilateral triangle as possible, thereby improving the quality of the mesh.

[0123] Algorithm steps:

[0124] 1. Start with a large triangle that contains all the points.

[0125] 2. Insert the points into the triangulation one by one. Each time you insert a point, check whether the point is within the circumcircle of the existing triangle.

[0126] 3. If the point is within the circumcircle of a triangle, split the triangle into three new triangles so that the new point becomes the vertex of one of the triangles.

[0127] 4. Repeat the above steps until all points have been inserted.

[0128] The Advancing-Front method is a layer-by-layer mesh generation method that starts from an initial boundary and gradually expands inward to form new mesh units. Algorithm steps:

[0129] 1. Define an initial boundary, usually the geometric boundary of the problem.

[0130] 2. Select a point on the boundary as the vertex of the new triangle.

[0131] 3. Select an edge from the border and connect it with the new vertex to form a new triangle.

[0132] 4. Update the boundary and add the opposite side of the newly formed triangle to the boundary.

[0133] 5. Repeat the above steps until all areas are meshed.

[0134] The connection between the turntable and the rocker arm is realized through the central axis bolt. This connection state is set as a fixed connection between the geometric bodies, with the turntable as the fixed target and the rocker arm as the contact target, and a coordinate system based on the central axis of the two is automatically generated. This involves determining the position and direction of the connection point. The following formula can be used to define the origin and direction of the coordinate system:

[0135]

[0136]

[0137] in, is the position vector of the origin of the coordinate system, is a unit vector along the medial axis; is the position vector of the center of gravity of the turntable geometry, It is the position vector of the center of gravity of the rocker arm geometry.

[0138] This logic algorithm is set up to release the freedom of the rocker arm's rotation, taking into account the actual rotation trend of the components rather than direct binding. In the connection between the turntable and the base, it is also set as a fixed connection between geometric bodies, with the base as the fixed target and the turntable as the contact target, and automatically generates a coordinate system based on the center axis of the bolt hole to release the freedom of the turntable's rotation.

[0139] The mechanical principles of stiffness analysis in statics are based on the basic concepts of structural mechanics. The formulas for calculating stress, strain and displacement in structural mechanics during numerical calculations are as follows:

[0140]

[0141] Solve for the displacement, where K is the global stiffness matrix. The stiffness matrix K is a square matrix whose size depends on the number of degrees of freedom of the system. For a system with n degrees of freedom, the stiffness matrix is ​​an n×n matrix. The stiffness matrix represents the relationship between the degrees of freedom of the structure, through which it can describe the force response of the structure under unit displacement. It is assembled from the stiffness matrices of all units; is the node displacement vector, which represents the displacement of all nodes. In this application, a 3D modeling method is adopted, and each node will correspond to 6 degrees of freedom, that is, it contains n×6 values; is the external nodal force vector, where the node The values ​​are distributed according to the above non-uniform load formula. Here, each node corresponds to the force and torque along the three axes of the rectangular coordinate system, totaling n×6 values. By introducing the boundary conditions of displacement and force, a certain set of linear equations can be obtained, and then the node displacement is solved by numerical methods. After obtaining the node displacement, the strain inside the unit is calculated according to the node displacement:

[0142]

[0143] in: is the strain vector, and B is the strain-displacement matrix. After obtaining the strain vector, according to the stress-strain formula:

[0144]

[0145] Calculate the stress, where is the stress vector, is the material elastic matrix.

[0146] S5.3, input the pre-processing settings of boundary constraints and load application of the benchmark physical test conditions, and obtain the finite element analysis result data through finite element solution.

[0147] S6, benchmarking the physical test data of the miter saw and the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, returning to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met to improve the reliability of the finite element analysis results.

[0148] Example 2

[0149] A system for testing and numerically calculating a miter saw, comprising:

[0150] The data processing module constructs a test data processing model, uses two-point eddy current induction electrical signals to collect displacement data about the miter saw, and converts the data of the two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around the coordinate axis;

[0151] A static test module, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data;

[0152] A dynamic test module uses the constructed test data processing model to perform a dynamic test of the miter saw to obtain dynamic test data;

[0153] The benchmarking module combines and analyzes static and dynamic data to obtain comprehensive physical test data of miter saws;

[0154] Prediction analysis module, builds the finite element analysis model of the miter saw and obtains the finite element analysis result data;

[0155] The correction module compares the physical test data of the miter saw with the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, it returns to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention with equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for testing and benchmarking a miter saw, characterized in that: The steps include: S1, constructing a test data processing model: using two-point eddy current induction electrical signals to collect displacement data about the miter saw, and converting the data of the two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around the coordinate axis; S2, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data; S3, using the constructed test data processing model to perform a dynamic test of the miter saw to obtain dynamic test data; S4, supplementing the static data with the dynamic data to obtain comprehensive physical test data of the miter saw; S5, constructing a finite element analysis model of the miter saw, including pre-processing settings of boundary constraints and load application of the digital three-dimensional model of the miter saw in accordance with the physical test conditions, and obtaining finite element analysis result data through finite element solution; S6, benchmarking the physical test data of the miter saw and the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, returning to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met.

2. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: Constructing the test data processing model includes the following steps: Using two-point eddy current induction electric signals to obtain distance data about the miter saw; Construct the X-axis, Y-axis and Z-axis directions in the space and determine the corresponding displacement data in each axis: set the direction parallel to the standard gravity direction of the detection point as the Z-axis, set the direction perpendicular to the standard gravity direction and along the slide bar of the miter saw as the X-axis, and determine the Y-axis of the coordinate system based on the directions of the X-axis and Z-axis according to the right-hand rule; Construct a method for calculating the deflection angle of the coordinate system rotating around the X-axis, Y-axis and Z-axis: convert the displacement offset components of the two test points in the Z-axis direction on the ZY plane into the deflection angle around the X-axis; convert the displacement offset components of the two points in the X-axis direction on the XY plane into the deflection angle around the Z axis; and convert the displacement offset components of the two points in the X-axis direction on the XZ plane into the deflection angle around the Y axis.

3. The method for testing and benchmarking a miter saw according to claim 2, characterized in that: The specific method of using two-point eddy current induction electrical signals to obtain displacement data about the miter saw is as follows: The real-time electrical signal is collected by eddy current, and the frequency and distribution of the electrical signal are obtained by using the fast Fourier transform algorithm; the formula of Fourier transform is: in, is the time domain signal, is its Fourier transform, j is the imaginary unit, is the angular frequency; Based on the frequency and distribution of the electrical signal, the phase is extracted according to the phase demodulation method; the frequency component and phase information of the signal can be obtained through Fourier transform. The phase demodulation technology relies on the analysis of this phase information. The formula for phase extraction can be expressed as: in, is the frequency component The phase angle at, arg represents the phase of the complex number; According to the phase changes at different time points, the extreme value and difference of displacement, displacement change value The calculation formula is: in, and are the phases at time t1 and t2, is the frequency component associated with the displacement change.

4. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: The static test process is as follows: S2.1, construct a static test model: use a saw blade replacement to increase the effective detection distance when the saw blade moves. The saw blade replacement has the same position and size as the center fixing hole and diameter of the original saw blade; set the parameters of the static test model; S2.2, based on the constructed test data processing model, test and process the data under different static tests, obtain the offset and deflection angle of the miter saw under different working conditions of the static test, and calculate the center of gravity position of the operator using the moment synthesis method; S2.3, obtain the center of gravity change curves under different static tests, and determine whether the change in accuracy is caused by the center of gravity shift by describing the influence of the center of gravity shift on the accuracy of the miter saw.

5. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: The dynamic test process is as follows: S3.1, build a dynamic test model: set key points and patch processing at the key points, and use external fixtures to fix the test equipment, and set the specific working conditions of the miter saw test, including the cutting angle, saw blade material, and the variables of the length and thickness of the cut wood; S3.2, based on the constructed test data processing model, the rigid deformation degree of the overall structure of the miter saw head is obtained by testing the key point data, and the dynamic offset and deflection angle of the miter saw under different variables are obtained.

6. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: The static tests include a left-hand pull test, a left-hand push test, a right-hand pull test, a right-hand push test, a two-hand pull test, a two-hand push test, and a two-hand motor support test.

7. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: Construct a finite element analysis model of a miter saw, including: S5.1, determine the main structural parts that affect the overall strength, and build a digital three-dimensional model of the miter saw based on the finite element analysis model; S5.2, determining the type of mesh setting in the finite element analysis model and using an unstructured mesh generation algorithm to automatically adjust the mesh size according to the size change of the digitized three-dimensional model; S5.3, input the pre-processing settings of boundary constraints and load application of the benchmark physical test conditions, and obtain the finite element analysis result data through finite element solution.

8. The method for testing and benchmarking a miter saw according to claim 7, characterized in that: Unstructured grid generation algorithms are used, including the Delaunay method and the Advancing-Front method.

9. The method for testing and benchmarking a miter saw according to claim 1, characterized in that: Benchmarking conditions: The data of each probe point in the physical test is compared with the data of the corresponding position in the finite element analysis results, and whether it is aligned is determined based on the absolute value and trend of the deformation.

10. A system for testing and numerically calculating a miter saw, comprising: The data processing module constructs a test data processing model, uses two-point eddy current induction electrical signals to collect displacement data about the miter saw, and converts the data of the two detection points into relative offset data based on a three-dimensional coordinate system and deflection angle data around the coordinate axis; A static test module, using the constructed test data processing model to perform a static test on the miter saw to obtain static test data; A dynamic test module uses the constructed test data processing model to perform a dynamic test of the miter saw to obtain dynamic test data; The benchmarking module combines and analyzes static and dynamic data to obtain comprehensive physical test data of miter saws; Prediction analysis module, builds the finite element analysis model of the miter saw and obtains the finite element analysis result data; The correction module compares the physical test data of the miter saw with the finite element analysis result data to determine whether the two meet the benchmarking conditions. If not, it returns to modify the parameters of the finite element analysis model of the miter saw until the benchmarking conditions are met.

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