Main shaft motion inclination error compensation method and system for numerical control machine tool

Abstract

The invention discloses a spindle motion inclination error compensation method and system for a numerical control machine tool, and the method comprises the steps: determining the installation positions of a first cross section and a second cross section of the numerical control machine tool and a non-contact laser displacement sensor, and obtaining the radial error data of the numerical control machine tool; filtering, parameterizing and reconstructing the radial error data of the numerical control machine tool in sequence to obtain preprocessed radial error data of the numerical control machine tool; and according to the preprocessed radial error data of the numerically-controlled machine tool, self-adaptive compensation is carried out on the feed amount of the cutting tool of the numerically-controlled machine tool, and the compensated feed amount of the cutting tool of the numerically-controlled machine tool is obtained. By using the method, the output angle of the machine tool can be standardized, so that the part machining precision of the numerical control machine tool is improved. The spindle motion inclination error compensation method and system for the numerical control machine tool can be widely applied to the technical field of intelligent manufacturing.

Description

Technical Field

[0001] The present invention relates to the field of intelligent manufacturing technology, and in particular to a spindle motion tilt error compensation method and system for a numerically controlled machine tool. Background Art

[0002] The spindle is a key functional component of the machine tool. The spindle accuracy (the spatial position accuracy of the spindle's rotary axis) determines the machining accuracy of the CNC machine tool to a large extent. The spindle's rotary axis is the installation and positioning reference for the tool or workpiece. Its spatial position accuracy ensures that the machine tool can process relatively perfect parts. The spindle has manufacturing errors. Under the combined effect of complex working conditions, its rotary axis will inevitably deviate from the ideal position, resulting in machining errors. This makes testing and real-time compensation technology an indispensable and important means of spindle accuracy and error analysis.

[0003] Modern machine tools are mainly precision machine tools. Human factors are excluded during processing. The errors such as roundness error and end surface flatness of the processed parts are all derived from the spindle rotation error. It should be noted that if the spindle motion is an ideal rotation motion, then the spatial position of its rotation axis relative to the tool holder (specific reference object) is unchanged. However, during the actual use of the spindle, the position of its rotation axis will always change due to the influence of the machine tool itself or various external factors, that is, the rotation error always exists. And the higher the accuracy level of the machine tool, the greater the proportion of the influence of the spindle motion error. In actual scenarios, the non-standard operation behavior causes the machine tool output angle to not meet the actual requirements, thereby reducing the accuracy of the machine tool processing parts. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a spindle motion tilt error compensation method and system for CNC machine tools, which can standardize the output angle of the machine tool and thus improve the machining accuracy of the parts by the CNC machine tool.

[0005] The first technical solution adopted by the present invention is: a spindle motion tilt error compensation method for a CNC machine tool, comprising the following steps:

[0006] Determine the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtain radial error data of the CNC machine tool;

[0007] The radial error data of the CNC machine tool is filtered, parameterized and reconstructed in sequence to obtain the preprocessed radial error data of the CNC machine tool;

[0008] According to the preprocessed radial error data of the CNC machine tool, the feed rate of the CNC machine tool cutting tool is adaptively compensated to obtain the compensated feed rate of the CNC machine tool cutting tool.

[0009] Furthermore, the step of measuring the rotation axis trajectory of the CNC machine tool spindle by using the non-contact laser displacement sensor to obtain the spindle axial processing error data under the load state of the CNC machine tool specifically includes:

[0010] Determine a first cross section and a second cross section of the CNC machine tool, wherein the first cross section represents a cross section of a spindle at a far motor end of the CNC machine tool, and the second cross section represents a cross section of a spindle at a near motor end of the CNC machine tool;

[0011] The first non-contact laser displacement sensor and the second non-contact laser displacement sensor are installed at a first section of the CNC machine tool at 90°, and the third non-contact laser displacement sensor and the fourth non-contact laser displacement sensor are installed at a second section of the CNC machine tool at 90°.

[0012] Further, the step of filtering, parameterizing and reconstructing the radial error data of the CNC machine tool in sequence to obtain the preprocessed radial error data of the CNC machine tool specifically includes:

[0013] Based on the operation of the CNC machine tool in a no-load state, the radial error data of the CNC machine tool is obtained by a non-contact laser displacement sensor, wherein the radial error data of the CNC machine tool includes the installation eccentricity error of the CNC machine tool, the shape error of the spindle of the CNC machine tool, and the radial rotation error of the spindle of the CNC machine tool;

[0014] The radial error data of the CNC machine tool is filtered by the first harmonic signal filtering method to obtain the radial error data of the CNC machine tool after the eccentricity error is eliminated;

[0015] Performing parameterization processing on the CNC machine tool spindle shape error in the CNC machine tool radial error data after eliminating the eccentricity error, and obtaining the CNC machine tool spindle shape error after parameters;

[0016] The radial rotation error of the CNC machine tool spindle in the radial error data of the CNC machine tool after eliminating the eccentricity error is reconstructed by the least square circular error evaluation method to obtain the reconstructed radial rotation error of the CNC machine tool spindle;

[0017] The preprocessed CNC machine tool radial error data is obtained by combining the parameterized CNC machine tool spindle shape error and the reconstructed CNC machine tool spindle radial rotation error.

[0018] Further, the step of filtering the radial error data of the CNC machine tool by a first harmonic signal filtering method to obtain the radial error data of the CNC machine tool after eliminating the eccentricity error specifically includes:

[0019] The radial error data of the CNC machine tool is divided into intervals and the data abnormality is eliminated to obtain the pre-processed radial error data of the CNC machine tool;

[0020] According to the eccentricity of the non-contact laser displacement sensor, the residual error of the pre-processed radial error data of the CNC machine tool is obtained;

[0021] The first Fourier coefficient of the residual error of the preprocessed radial error data of the numerical control machine tool is obtained and combined with the preprocessed radial error data of the numerical control machine tool for elimination processing to obtain the radial error data of the numerical control machine tool after eliminating the eccentricity error.

[0022] Furthermore, the expression for parameterizing the shape error of the CNC machine tool spindle is:

[0023]

[0024] In the above formula, Δr k It represents the shape error of the kth sampling point of the outer contour of the measured section of the CNC machine tool spindle. It represents the mean value of all data collected by the sensor during the CNC machine tool's continuous operation of m circles under no-load condition after eliminating the installation eccentricity error. represents the mean value of the data belonging to the kth sampling point, n represents the number of sampling points, m represents the number of consecutive cycles of the CNC machine tool under no-load condition, S X Represents the first non-contact laser displacement sensor, S Xk represents the kth non-contact laser displacement sensor, S Xi represents the i-th data collected by the sensor when the spindle is in the no-load state, S X,k+n·m represents the data collected by the k-th sampling point in the j-th circle, j represents the data collected in the j-th circle (j=1, 2, ...m), and i represents the i-th data collected by all sampling points in the m-th circle (j=1, 2, ...n×m).

[0025] Further, the step of reconstructing the radial rotation error of the CNC machine tool spindle in the radial error data of the CNC machine tool after eliminating the eccentricity error by the least squares circular error evaluation method to obtain the reconstructed radial rotation error of the CNC machine tool spindle specifically includes:

[0026] Construct the absolute coordinate system of the CNC machine tool according to the average line of the CNC machine tool spindle rotation axis;

[0027] Set a vector to rotate clockwise around the X-axis and Y-axis of the absolute coordinate system of the CNC machine tool in sequence to obtain the deflection angle;

[0028] The radial rotation error of the spindle of the CNC machine tool is reconstructed according to the deflection angle to obtain the reconstructed radial rotation error of the spindle of the CNC machine tool.

[0029] Further, the step of adaptively compensating the feed rate of the CNC machine tool cutting tool according to the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed rate specifically includes:

[0030] Construct the CNC machine tool space Cartesian rectangular coordinate system according to the average line of the CNC machine tool spindle rotation axis;

[0031] Based on the CNC machine tool spatial Cartesian rectangular coordinate system, determining the mapping relationship expression of the coordinate position of the CNC machine tool cutting tool, the axis center offset of the first section and the axis center offset of the second section;

[0032] Determine the feed compensation amount of the cutting tool of the CNC machine tool according to the mapping relationship expression and preset the compensation threshold;

[0033] If the feed compensation amount of the CNC machine tool cutting tool does not meet the preset compensation threshold, no adaptive compensation is performed;

[0034] If the CNC machine tool cutting tool feed compensation amount meets the preset compensation threshold, the CNC machine tool cutting tool feed amount is adaptively compensated through the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed amount.

[0035] Furthermore, the mapping relationship expression of the coordinate position of the CNC machine tool cutting tool, the first section axis center offset and the second section axis center offset is specifically as follows:

[0036]

[0037] In the above formula, L represents the axial distance between the first section to be measured and the second section to be measured, x 刀具 -x b Indicates the axial distance between the tool position that changes in real time during the machining process and the second section being measured, Δr A and Δr B Respectively represent the radial rotation error of the first section and the second section in the X-axis direction, Δr 刀具-x Indicates the component of the adaptive compensation of the tool feed amount in the X-axis direction.

[0038] Furthermore, it also includes constructing a mapping relationship data table according to the load size of the CNC machine tool, the feed amount of the CNC machine tool cutting tool and the radial error data of the CNC machine tool to achieve self-prediction of the adaptive compensation amount of the CNC machine tool cutting tool feed amount.

[0039] The second technical solution adopted by the present invention is: a spindle motion tilt error compensation system for a CNC machine tool, comprising:

[0040] The first module is used to determine the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtain the radial error data of the CNC machine tool;

[0041] The second module is used to filter, parameterize and reconstruct the radial error data of the CNC machine tool in sequence to obtain the pre-processed radial error data of the CNC machine tool;

[0042] The third module is used to adaptively compensate the feed rate of the CNC machine tool cutting tool according to the pre-processed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed rate.

[0043] The beneficial effects of the method and system of the present invention are as follows: the present invention determines the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, thereby obtaining the radial error data of the CNC machine tool, further filtering, parameterizing and reconstructing the radial error data of the CNC machine tool in sequence, obtaining the preprocessed radial error data of the CNC machine tool, and obtaining the tilt condition of the spindle under the cutting load according to the data analysis, and reconstructing the position of the rotary axis of the CNC machine tool, thereby solving the problem of the influence of data packet loss, data mutation and non-standard output angle of the machine tool on the results in actual scenarios, and finally performing adaptive compensation for the feed amount of the CNC machine tool cutting tool according to the preprocessed radial error data of the CNC machine tool, realizing the prediction of the adaptive compensation amount of the cutting tool feed amount, and comparing it with the actual compensation amount, thereby improving the processing accuracy of the CNC machine tool on the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flowchart of the steps of a spindle motion tilt error compensation method for a CNC machine tool of the present invention;

[0045] Figure 2 It is a structural block diagram of a spindle motion tilt error compensation system for CNC machine tools of the present invention;

[0046] Figure 3 It is a schematic diagram of real-time compensation of spindle motion tilt error of a CNC machine tool provided by a specific embodiment of the present invention;

[0047] Figure 4 It is a schematic diagram of installing a laser displacement sensor based on the working principle of the measuring point method provided by a specific embodiment of the present invention;

[0048] Figure 5 It is a schematic diagram of the principle of real-time information interaction between a CNC machine tool and a sensor provided by a specific embodiment of the present invention;

[0049] Figure 6 It is a schematic diagram of the principle of a method for testing the spindle rotation trajectory of a CNC machine tool provided by a specific embodiment of the present invention;

[0050] Figure 7 It is a schematic diagram of spindle tilt error calculation provided by a specific embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0052] Reference Figure 1 The present invention provides a spindle motion tilt error compensation method for a CNC machine tool, the method comprising the following steps:

[0053] S100, determining the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtaining radial error data of the CNC machine tool;

[0054] Specifically, a first section (measuring point A) and a second section (measuring point B) of the CNC machine tool are determined, the first section represents the spindle section at the far motor end of the CNC machine tool, and the second section represents the spindle section at the near motor end of the CNC machine tool; the first non-contact laser displacement sensor and the second non-contact laser displacement sensor are installed at 90° on the first section of the CNC machine tool, and the third non-contact laser displacement sensor and the fourth non-contact laser displacement sensor are installed at 90° on the second section of the CNC machine tool.

[0055] Further, it should be noted that, in this embodiment, the real-time measurement method for first determining the machining error generated by the CNC machine tool spindle under the cutting force load is to adopt a point measurement method based on a non-contact laser displacement sensor, referring to Figure 4 The measurement principle is as follows: 4 non-contact laser displacement sensors are used: two pairs of mutually perpendicular displacement sensors are used at different cross-section positions of the spindle. The first non-contact laser displacement sensor and the second non-contact laser displacement sensor measure the spindle error of the first section (far motor end); the third non-contact laser displacement sensor and the fourth non-contact laser displacement sensor measure the spindle error of the second section (near motor end).

[0056] Furthermore, the required hardware measurement equipment and its data transmission path are determined, such as Figure 5As shown in the figure, the hardware measurement equipment includes: CNC machine tool system, programmable logic controller (PLC), network switch, non-contact laser displacement sensor, sensor bracket, power supply voltage converter, I / O module, etc. Under load, in order to achieve adaptive compensation of CNC machine tool tools, it is necessary to rely on the data collected in real time by four sensors, the axial position coordinates of the tool during work, and the angular position information of the machine tool spindle, which are three parameters that change over time. To this end, the I / O machine receives the dynamic data provided by the sensor, the tool coordinate position and spindle angular position information output by the CNC machine tool in real time, and performs real-time data processing and calculation internally, and finally obtains the compensation amount, which is fed back to the compensation interface of the CNC machine tool to optimize the processing accuracy.

[0057] Secondly, it is also necessary to determine the sensor installation method, position parameters and geometric parameters of the CNC machine tool spindle. The installation of the laser displacement sensor requires that the two sensors located on the same section be distributed at 90° while ensuring stability. In order to avoid eccentric errors in the measurement process, the intersection of the two sensors should be located at the spindle axis as much as possible. Therefore, it is necessary to design a sensor bracket that can be precisely fine-tuned in the measurement direction. The geometric parameters include the axial spacing between the two measured sections, the radius of the spindle, the spindle length and other geometric parameters and the spindle's rotation speed, rotation direction and other information.

[0058] Finally, the laser displacement sensor is used to measure the rotation axis trajectory of the CNC machine tool spindle. Figure 6 As shown in the figure, according to the analysis of the spindle spatial error, the spindle axial error is divided into radial error, axial error and tilt error in spatial distribution. The radial error of the first section can be measured by relying on the first non-contact laser displacement sensor and the second non-contact laser displacement sensor; the radial error of the second section can be measured by relying on the third non-contact laser displacement sensor and the fourth non-contact laser displacement sensor; the axial tilt error of the spindle is obtained by coupling the radial runout error of the first section and the second section; as for the axial error, it is negligible; according to the measurement principle of the machine tool spindle error of the measuring point method, the radial error measured by the sensor can be divided into four parts: the installation eccentricity error of the sensor, the shape error and radial rotation error of the measured section of the spindle, and the random error caused by external factors; the influence of the environment is weakened as much as possible, and the system errors of the installation eccentricity error of the sensor and the shape error of the measured section of the spindle are separated by using the data processing method to obtain the spindle radial rotation error that changes with time.

[0059] S200, performing filtering, parameterization and reconstruction processing on the radial error data of the CNC machine tool in sequence to obtain the pre-processed radial error data of the CNC machine tool;

[0060] S210, based on the CNC machine tool running in a no-load state, obtaining radial error data of the CNC machine tool through a non-contact laser displacement sensor, wherein the radial error data of the CNC machine tool includes an installation eccentricity error of the CNC machine tool, a shape error of a spindle of the CNC machine tool, and a radial rotation error of a spindle of the CNC machine tool;

[0061] S220, filtering the radial error data of the CNC machine tool by a first harmonic signal filtering method to obtain the radial error data of the CNC machine tool after eliminating the eccentricity error;

[0062] Specifically, the radial error data of the CNC machine tool is divided into intervals and the data anomalies are eliminated to obtain the preprocessed radial error data of the CNC machine tool; the residual error of the preprocessed radial error data of the CNC machine tool is obtained according to the eccentricity of the non-contact laser displacement sensor; the first-order Fourier coefficient of the residual error of the preprocessed radial error data of the CNC machine tool is obtained and combined with the preprocessed radial error data of the CNC machine tool for elimination processing to obtain the radial error data of the CNC machine tool after the eccentricity error is eliminated.

[0063] In this embodiment, the "first harmonic signal filtering" method is used to separate the sensor installation eccentricity error when the machine tool is in a no-load state. The preliminary data collection stage of error separation ensures that the machine tool operates in a no-load state. First, the machine tool spindle rotates continuously for m circles, and the data acquisition system reads the data at intervals of 10ms. Under this setting, theoretically, the system will collect n sets of data for each completed circle. This means that every 10ms, the AI ​​machine receives a set of comprehensive information including four sensor data, the rotation angle of the machine tool spindle, and the specific position coordinates of the cutting tool. The entire acquisition process will generate a total of n×m sets of data.

[0064] After data collection is completed, considering the packet loss during data transmission and the misalignment of the spindle rotation angles collected in each circle (theoretically, the n spindle angle information collected in each circle should correspond one to one, but this cannot be guaranteed in actual applications), reset n = max{n k}(k=1,2,...,m), and divide 360° into n intervals, divide the collected data according to these n intervals, and count the collected values ​​in the same interval as a sampling point, ensuring that each angle interval has at least one sampling point, and at the same time eliminate the data collected by the sensor that has a sudden change.

[0065] Since the sensor needs to be installed manually when measuring the spindle rotation error, manual operation will inevitably cause installation eccentricity error. However, since the installation eccentricity error is a first harmonic signal, the first harmonic can be filtered to eliminate the impact of the eccentricity error on the measurement result as much as possible. Assume that the first non-contact laser displacement sensor S located at the first section XThe measurement is performed in the X-axis direction (the tool feed direction during machine tool processing), and the data X(θ) collected by the sensor is: X(θ)=OA×cosθ.

[0066] Among them, O is the theoretical axis determined by two laser displacement sensors, A is the actual axis, and OA represents the eccentricity.

[0067] S X Taking the data collected by the sensor as an example (i = 1, 2, ..., n × m), the residual error is calculated and its expression is:

[0068]

[0069] Find the first-order Fourier coefficient, the expression is:

[0070]

[0071] Eliminate eccentricity error, the expression is:

[0072] AX′(θ i )=X(θ i )-[a1·cos(θ i )+b1·sin(θ i )]

[0073] ΔX′(θ i ) is S X The sensor’s collected data is the value after eliminating the installation eccentricity error. At this time, ΔX′(θ i ) represents the sum of the radial rotation error of the machine tool spindle and the shape error of the measured spindle section.

[0074] S230, performing parameterization processing on the CNC machine tool spindle shape error in the CNC machine tool radial error data after eliminating the eccentricity error, to obtain the parameterized CNC machine tool spindle shape error;

[0075] In this embodiment, the data collected by the sensor is processed in the no-load state of the machine tool to complete the parameterization of the shape error of the CNC machine tool spindle, and its expression is:

[0076]

[0077] In the above formula, Δr k It represents the shape error of the kth sampling point of the outer contour of the measured section of the CNC machine tool spindle. It represents the mean value of all data collected by the sensor during the CNC machine tool's continuous operation of m circles under no-load condition after eliminating the installation eccentricity error. represents the mean value of the data belonging to the kth sampling point, n represents the number of sampling points, m represents the number of consecutive cycles of the CNC machine tool under no-load condition, SX Represents the first non-contact laser displacement sensor, S Xk represents the kth non-contact laser displacement sensor, S Xi represents the i-th data collected by the sensor when the spindle is in the no-load state, S X,k+n·m represents the data collected by the k-th sampling point in the j-th circle, j represents the data collected in the j-th circle (j=1, 2, ...m), and i represents the i-th data collected by all sampling points in the m-th circle (j=1, 2, ...n×m).

[0078] By fitting the spindle shape errors and spindle radius of these n consecutive sampling points, the shape curve of the complete spindle measured section and the shape error parameters of each point can be obtained.

[0079] S240, reconstructing the radial rotation error of the CNC machine tool spindle in the radial error data of the CNC machine tool after eliminating the eccentricity error by using a least square circular error evaluation method to obtain a reconstructed radial rotation error of the CNC machine tool spindle;

[0080] Specifically, an absolute coordinate system of the CNC machine tool is constructed according to the average line of the rotation axis of the spindle of the CNC machine tool; a vector is set to rotate clockwise around the X-axis and the Y-axis of the absolute coordinate system of the CNC machine tool in sequence to obtain a deflection angle; the radial rotation error of the spindle of the CNC machine tool is reconstructed according to the deflection angle to obtain a reconstructed radial rotation error of the spindle of the CNC machine tool.

[0081] In this embodiment, according to the theory of "least square circular error evaluation method", the position reconstruction of the rotation axis of the CNC machine tool spindle is completed, such as Figure 7 As shown in the figure, according to the uniqueness of the average line of the main shaft rotation axis, the absolute coordinate system is established using the average line of the axis. The first section is selected as the reference plane, and the radial rotation error measured by this section is used as the reference. The spindle inclination rotation error can be obtained by the radial rotation error measured by the second section.

[0082] Based on the above absolute coordinate system, assuming there is a vector Assume that its starting point coordinates are (x1, y1, z1) and its end point coordinates are (x1, y1, z1+l). Then the vector First rotate φ clockwise around the X axis x , and then rotate φ clockwise around the Y axis y , after transformation, the new vector is The starting point of the coordinates is (x1, y1, z1), and the ending point is (x2, y2, z2). The new vector for:

[0083]

[0084] Where R x , Ry The coordinate transformation matrix (curl) that represents the clockwise rotation of a vector around the X and Y axes can be expressed as follows:

[0085]

[0086] The deflection angle is expressed as:

[0087]

[0088]

[0089] From the analysis, it can be seen that when l is large enough, the influence of the rotation order of the vector around the axis on the deflection angle can be ignored. The radial rotation error of the high-precision spindle is at the micron or even sub-micron level, while l is at the millimeter level. Therefore, the calculation result of the deflection angle can be simplified to:

[0090]

[0091] In the above formula, φ x Indicates the clockwise rotation angle around the X axis, φ y Indicates the clockwise rotation angle around the Y axis.

[0092] S250, combining the parameterized CNC machine tool spindle shape error and the reconstructed CNC machine tool spindle radial rotation error to obtain preprocessed CNC machine tool radial error data.

[0093] S300, adaptively compensating the feed rate of the CNC machine tool cutting tool according to the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed rate.

[0094] Specifically, a CNC machine tool space Cartesian rectangular coordinate system is constructed according to the average line of the CNC machine tool spindle rotation axis; based on the CNC machine tool space Cartesian rectangular coordinate system, the mapping relationship expression of the coordinate position of the CNC machine tool cutting tool, the first section axis center offset and the second section axis center offset is determined; according to the mapping relationship expression, the CNC machine tool cutting tool feed compensation amount is determined and a compensation threshold is preset; if the CNC machine tool cutting tool feed compensation amount does not meet the preset compensation threshold, no adaptive compensation is performed; if the CNC machine tool cutting tool feed compensation amount meets the preset compensation threshold, the CNC machine tool cutting tool feed compensation is adaptively compensated for by using the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed amount.

[0095] In this embodiment, based on the analysis of the working process of the CNC machine tool, in addition to the radial clearance at both ends of the spindle causing the axis trajectory to shift, the cutting tool will also impose a radial load on the spindle during the machining process, causing the spindle to deform radially. Therefore, the adaptive compensation amount of the tool feed rate is a function of the axial coordinate position of the cutting tool, the axis offset of the first section end being measured, and the axis offset of the second section end being measured.

[0096] A spatial Cartesian rectangular coordinate system is established based on the average line of the main shaft rotation axis, and the theoretical axis center of the second section end to be measured is taken as the origin of the coordinate system. The mapping relationship is used to obtain:

[0097]

[0098] In the above formula, L represents the axial distance between the first section to be measured and the second section to be measured, x 刀具 -x b Indicates the axial distance between the tool position that changes in real time during the machining process and the second section being measured, Δr A and Δr B Respectively represent the radial rotation error of the first section and the second section in the X-axis direction, Δr 刀具-x Indicates the component of the adaptive compensation of the tool feed amount in the X-axis direction.

[0099] According to the actual shaking analysis of the tool during operation, in addition to the projection value in the X-axis direction directly calculated above, the shaking of the spindle in the Y-axis direction will also affect the relative position of the cutting tool and the axis. Therefore, the feed compensation of the tool should also consider the influence of the radial rotation error in the Y-axis direction:

[0100]

[0101] Among them, r represents the radius of the spindle section being measured, Δy represents the radial rotation error of the cutting tool in the Y-axis direction, and Δr 刀具-y Refers to the component of the adaptive compensation of the tool feed amount in the Y-axis direction.

[0102] In the real-time axis trajectory monitoring system, when the axis trajectory deviates from the origin, it should be compensated accordingly. However, considering the response time of the system and the feed accuracy of the tool, in actual application, this method will instead cause serious consequences such as reduced machining accuracy. Therefore, it is necessary to set a threshold in the compensation accuracy range of the tool. When the trajectory exceeds the threshold, compensation is performed, otherwise it is ignored.

[0103] Finally, it should be noted that in this embodiment, a parameter mapping relationship between cutting speed, load size and tool adaptive compensation is established, and each parameter is changed by the control variable method and the parameter change of the tool compensation is recorded to establish a sample set of CNC machine tool cutting parameters; a parameter mapping relationship between cutting speed, load size and tool adaptive compensation is established, and based on the CNC machine tool cutting parameter sample set, a binary nonlinear regression equation is used to approximate the sample set data to obtain the mapping relationship between each parameter and the cutting tool adaptive compensation during the CNC machine tool cutting load processing. The mapping relationship can be used to predict the adaptive compensation of the cutting tool feed amount, and the predicted value and the actual value can be used as a comparison to diagnose the fault of the CNC machine tool.

[0104] Reference Figure 2 , a spindle motion tilt error compensation system for CNC machine tools, comprising:

[0105] The first module 201 is used to determine the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtain radial error data of the CNC machine tool;

[0106] The second module 202 is used to filter, parameterize and reconstruct the radial error data of the CNC machine tool in sequence to obtain the pre-processed radial error data of the CNC machine tool;

[0107] The third module 203 is used to adaptively compensate the feed rate of the cutting tool of the CNC machine tool according to the pre-processed radial error data of the CNC machine tool to obtain the compensated feed rate of the cutting tool of the CNC machine tool.

[0108] The contents of the above method embodiments are all applicable to the present system embodiments. The functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0109] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments, and those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention.

Claims

1. A spindle motion tilt error compensation method for CNC machine tools, characterized in that: The following steps are involved: Determine the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtain radial error data of the CNC machine tool; The radial error data of the CNC machine tool is filtered, parameterized and reconstructed in sequence to obtain the preprocessed radial error data of the CNC machine tool; According to the preprocessed radial error data of the CNC machine tool, the feed rate of the CNC machine tool cutting tool is adaptively compensated to obtain the compensated feed rate of the CNC machine tool cutting tool.

2. According to claim 1, a spindle motion tilt error compensation method for a CNC machine tool is characterized in that: The step of measuring the rotation axis trajectory of the spindle of the CNC machine tool by the point measurement method based on the non-contact laser displacement sensor to obtain the spindle axial processing error data under the load state of the CNC machine tool specifically includes: Determine a first cross section and a second cross section of the CNC machine tool, wherein the first cross section represents a cross section of a spindle at a far motor end of the CNC machine tool, and the second cross section represents a cross section of a spindle at a near motor end of the CNC machine tool; The first non-contact laser displacement sensor and the second non-contact laser displacement sensor are installed at a first section of the CNC machine tool at 90°, and the third non-contact laser displacement sensor and the fourth non-contact laser displacement sensor are installed at a second section of the CNC machine tool at 90°.

3. The spindle motion tilt error compensation method for a CNC machine tool according to claim 2, characterized in that: The step of filtering, parameterizing and reconstructing the radial error data of the CNC machine tool in sequence to obtain the preprocessed radial error data of the CNC machine tool specifically includes: Based on the operation of the CNC machine tool in a no-load state, the radial error data of the CNC machine tool is obtained by a non-contact laser displacement sensor, wherein the radial error data of the CNC machine tool includes the installation eccentricity error of the CNC machine tool, the shape error of the spindle of the CNC machine tool, and the radial rotation error of the spindle of the CNC machine tool; The radial error data of the CNC machine tool is filtered by the first harmonic signal filtering method to obtain the radial error data of the CNC machine tool after the eccentricity error is eliminated; Performing parameterization processing on the CNC machine tool spindle shape error in the CNC machine tool radial error data after eliminating the eccentricity error, and obtaining the CNC machine tool spindle shape error after parameters; The radial rotation error of the CNC machine tool spindle in the radial error data of the CNC machine tool after eliminating the eccentricity error is reconstructed by the least square circular error evaluation method to obtain the reconstructed radial rotation error of the CNC machine tool spindle; The preprocessed CNC machine tool radial error data is obtained by combining the parameterized CNC machine tool spindle shape error and the reconstructed CNC machine tool spindle radial rotation error.

4. The spindle motion tilt error compensation method for a CNC machine tool according to claim 3, characterized in that: The step of filtering the radial error data of the CNC machine tool by the first harmonic signal filtering method to obtain the radial error data of the CNC machine tool after eliminating the eccentricity error specifically includes: The radial error data of the CNC machine tool is divided into intervals and the data abnormality is eliminated to obtain the pre-processed radial error data of the CNC machine tool; According to the eccentricity of the non-contact laser displacement sensor, the residual error of the pre-processed radial error data of the CNC machine tool is obtained; The first Fourier coefficient of the residual error of the preprocessed radial error data of the numerical control machine tool is obtained and combined with the preprocessed radial error data of the numerical control machine tool for elimination processing to obtain the radial error data of the numerical control machine tool after eliminating the eccentricity error.

5. The spindle motion tilt error compensation method for a CNC machine tool according to claim 4, characterized in that: The expression for parameterizing the shape error of the CNC machine tool spindle is: In the above formula, Δr k It represents the shape error of the kth sampling point of the outer contour of the measured section of the CNC machine tool spindle. It represents the mean value of all data collected by the sensor during the CNC machine tool's continuous operation of m circles under no-load condition after eliminating the installation eccentricity error. represents the mean value of the data belonging to the kth sampling point, n represents the number of sampling points, m represents the number of consecutive cycles of the CNC machine tool under no-load condition, S X Represents the first non-contact laser displacement sensor, S Xk represents the kth non-contact laser displacement sensor, S Xi represents the i-th data collected by the sensor when the spindle is in the no-load state, S X,k+n·m represents the data collected by the k-th sampling point in the j-th circle, j represents the data collected in the j-th circle (j=1, 2, ...m), and i represents the i-th data collected by all sampling points in the m-th circle (j=1, 2, ...n×m).

6. The spindle motion tilt error compensation method for a CNC machine tool according to claim 5, characterized in that: The step of reconstructing the radial rotation error of the CNC machine tool spindle in the radial error data of the CNC machine tool after eliminating the eccentricity error by the least squares circular error evaluation method to obtain the reconstructed radial rotation error of the CNC machine tool spindle specifically includes: Construct the absolute coordinate system of the CNC machine tool according to the average line of the CNC machine tool spindle rotation axis; Set a vector to rotate clockwise around the X-axis and Y-axis of the absolute coordinate system of the CNC machine tool in sequence to obtain the deflection angle; The radial rotation error of the spindle of the CNC machine tool is reconstructed according to the deflection angle to obtain the reconstructed radial rotation error of the spindle of the CNC machine tool.

7. A spindle motion tilt error compensation method for a CNC machine tool according to claim 6, characterized in that: The step of adaptively compensating the feed rate of the CNC machine tool cutting tool according to the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed rate specifically includes: Construct the CNC machine tool space Cartesian rectangular coordinate system according to the average line of the CNC machine tool spindle rotation axis; Based on the CNC machine tool spatial Cartesian rectangular coordinate system, determining the mapping relationship expression of the coordinate position of the CNC machine tool cutting tool, the axis center offset of the first section and the axis center offset of the second section; Determine the feed compensation amount of the cutting tool of the CNC machine tool according to the mapping relationship expression and preset the compensation threshold; If the feed compensation amount of the CNC machine tool cutting tool does not meet the preset compensation threshold, no adaptive compensation is performed; If the CNC machine tool cutting tool feed compensation amount meets the preset compensation threshold, the CNC machine tool cutting tool feed amount is adaptively compensated through the preprocessed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed amount.

8. The spindle motion tilt error compensation method for a CNC machine tool according to claim 7, characterized in that: The mapping relationship expression of the coordinate position of the CNC machine tool cutting tool, the first section axis center offset and the second section axis center offset is specifically as follows: In the above formula, L represents the axial distance between the first section to be measured and the second section to be measured, x 刀具 -x b Indicates the axial distance between the tool position that changes in real time during the machining process and the second section being measured, Δr A and Δr B Respectively represent the radial rotation error of the first section and the second section in the X-axis direction, Δr 刀具-x Indicates the component of the adaptive compensation of the tool feed amount in the X-axis direction.

9. The spindle motion tilt error compensation method for a CNC machine tool according to claim 8, characterized in that: It also includes constructing a mapping relationship data table according to the load size of the CNC machine tool, the feed amount of the CNC machine tool cutting tool and the radial error data of the CNC machine tool, so as to realize self-prediction of the adaptive compensation amount of the CNC machine tool cutting tool feed amount.

10. A spindle motion tilt error compensation system for CNC machine tools, characterized in that: Includes the following modules: The first module is used to determine the first cross section and the second cross section of the CNC machine tool and the installation position of the non-contact laser displacement sensor, and obtain the radial error data of the CNC machine tool; The second module is used to filter, parameterize and reconstruct the radial error data of the CNC machine tool in sequence to obtain the pre-processed radial error data of the CNC machine tool; The third module is used to adaptively compensate the feed rate of the CNC machine tool cutting tool according to the pre-processed CNC machine tool radial error data to obtain the compensated CNC machine tool cutting tool feed rate.

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