Vibration identification and trajectory correction method for milling of large-size parts

Abstract

The application discloses a vibration identification and track correction method for milling of large-size parts, and relates to the technical field of numerical control machining control, which comprises the following steps: correcting the local dynamic compliance of the reference according to the vibration propagation degree by using the dynamic state parameters of the tool position, determining the local dynamic compliance along the continuous tool positions which have not been machined, determining the expected tool relief from the local dynamic compliances and converting the expected tool relief into the target track offset, determining the track offset disturbance degree by combining the difference of the target track offset of the adjacent tool positions and the tool position spacing, determining the allowed disturbance range according to the local dynamic compliance, when the track offset disturbance degree exceeds the allowed disturbance range, distributing the target track offset which exceeds the allowed disturbance range along the continuous tool positions which have not been machined step by step until the track offset disturbance degrees of the adjacent tool positions are all within the allowed disturbance range, and generating the local correction track of the unprocessed tool position. The application realizes the distributed correction of the over-limit track offset of the industrial control system.

Description

Technical Field

[0001] This invention relates to the field of CNC machining control technology, and in particular to a vibration identification and trajectory correction method for milling large-size parts. Background Technology

[0002] With the increasing demand for high-precision, large-size parts machining in aerospace, energy equipment, and large mold industries, the milling of large-size parts is gradually developing towards higher material removal rates and higher machining accuracy. These parts exhibit significant local stiffness differences and continuously changing material removal states, making them prone to vibration, tool deflection, and localized machining errors during milling. Existing industrial control systems typically identify abnormal vibrations through vibration signals and adjust the spindle speed, feed rate, or depth of cut. Simultaneously, they set trajectory compensation amounts based on tool deformation, workpiece deformation, or machining errors to locally correct the tool's motion trajectory.

[0003] During continuous milling of large parts, material removal causes changes in the local structural state and vibration propagation state. Existing industrial control systems, which use fixed dynamic parameters or single vibration characteristics, struggle to accurately characterize the local dynamic response at different tool positions. Current trajectory compensation methods typically rely on offset or geometric continuity for amplitude limiting and smoothing, failing to adequately consider the dynamic excitation caused by trajectory offset changes and differences in local dynamic compliance. When the offset changes too rapidly between adjacent tool positions, local vibrations can be exacerbated. Furthermore, for trajectory offsets exceeding the allowable disturbance range, there is a lack of methods to redistribute them along unprocessed continuous tool positions, making it difficult to balance tool deflection compensation with milling stability. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a vibration identification and trajectory correction method for milling large-size parts, which solves the problems of inaccurate characterization of local dynamic states and easy vibration caused by trajectory offset changes during the milling process of large-size parts.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a vibration identification and trajectory correction method for milling large-size parts, comprising: acquiring actual tool position and vibration signal; determining the material removal range based on the actual tool position and establishing a correlation to form tool position machining correlation information; determining the reference local dynamic compliance of the current tool position based on the material removal range, and obtaining the vibration propagation degree from the vibration signal to obtain tool position dynamic state parameters; using the tool position dynamic state parameters, correcting the reference local dynamic compliance according to the vibration propagation degree, and determining the local dynamic compliance along the unprocessed continuous tool positions; determining the expected tool deflection amount from each local dynamic compliance and converting it into a target trajectory offset. The quantity is then combined with the difference in the target trajectory offset of adjacent tool positions and the tool position spacing to determine the degree of trajectory offset disturbance. The allowable disturbance range is determined according to the local dynamic compliance. When the degree of trajectory offset disturbance exceeds the allowable disturbance range, the target trajectory offset amount exceeding the allowable disturbance range is distributed step by step along the continuous tool positions that have not yet been processed until the degree of trajectory offset disturbance of each adjacent tool position is within the allowable disturbance range, generating the local correction trajectory of the unprocessed tool position. The tool position is controlled to mill according to the local correction trajectory of the unprocessed tool position, and the material removal range is updated according to the actual execution position and then written into the tool position processing association information to form the updated tool position processing association information.

[0008] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps of determining the material removal range and establishing the correlation to form tool position machining correlation information are as follows:

[0009] Collect actual tool position and vibration signal, match each vibration sampling point to the actual tool position at the corresponding time according to the collection time, and determine the vibration signal of each actual tool position;

[0010] The tool sweep range is determined by the continuous movement segment of the actual tool position, and compared with the range of material that has not yet been removed to determine the material removal range. Then, the material removal range is correlated with the vibration signal to form tool position machining correlation information.

[0011] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps for determining the reference local dynamic compliance of the current tool position and obtaining the vibration propagation degree from the vibration signal to obtain the tool position dynamic state parameters are as follows:

[0012] Based on the material removal range, determine the local material action area of ​​the current tool position, calculate the percentage of unremoved material to obtain the material retention degree, then determine the initial local dynamic compliance degree before machining at the current tool position, and correct it according to the material retention degree to obtain the baseline local dynamic compliance degree;

[0013] The vibration amplitudes of the spindle-side vibration and the workpiece-side vibration within the same characteristic frequency band are extracted from the vibration signal. The vibration amplitude changes are compared to determine the degree of vibration propagation. Then, the vibration amplitudes are aggregated with the reference local dynamic compliance according to the current tool position to obtain the tool position dynamic state parameters.

[0014] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps of correcting the reference local dynamic compliance according to the degree of vibration propagation and determining the local dynamic compliance along the unprocessed continuous tool path are as follows:

[0015] By using the dynamic state parameters of the tool position, the vibration propagation degree of the previous adjacent tool position is obtained and compared with the vibration propagation degree of the current tool position to obtain the propagation deviation. Then, the reference local dynamic compliance is corrected according to the magnitude and direction of the propagation deviation to obtain the tool position compliance.

[0016] Using the tool position compliance as the starting value, the spatial overlap area of ​​adjacent local material action areas is compared along the unprocessed continuous tool positions. The difference between the tool position compliance and the reference local dynamic compliance is gradually reduced according to the spatial overlap area and superimposed on the reference local dynamic compliance of each continuous tool position to form the local dynamic compliance.

[0017] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps of determining the expected tool deflection amount from each local dynamic compliance and converting it into the target trajectory offset amount are as follows:

[0018] Based on the change in vibration amplitude at the current tool position, and combined with the local dynamic compliance of each consecutive tool position, the corresponding displacement response is obtained, and each displacement response is converted into the expected deflection amount for each consecutive tool position.

[0019] The expected deflection amount of each consecutive tool position is matched with the direction of the largest vibration amplitude in the vibration signal and used as the expected deflection direction. Then, the expected deflection amount is mapped to the machining trajectory of the tool position in the opposite direction of the expected deflection direction to obtain the target trajectory offset amount of each consecutive tool position.

[0020] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps for determining the degree of trajectory offset disturbance by combining the difference in the target trajectory offset of adjacent tool positions with the tool position spacing are as follows:

[0021] Compare the target trajectory offsets of each consecutive tool position, calculate the difference in target trajectory offsets between adjacent tool positions, and determine the offset change between adjacent tool positions by combining the spacing of adjacent tool positions along the machining trajectory. Then, record each offset change according to the order of the tool positions in the machining trajectory to obtain the trajectory offset change.

[0022] Based on the trajectory offset change, the offset change between adjacent tool positions is compared according to the tool position arrangement order in the machining trajectory. Tool positions with continuously increasing or sudden increases in offset change are identified as disturbed tool positions. The difference in offset change between the disturbed tool position and its adjacent tool positions is calculated to determine the degree of trajectory offset disturbance.

[0023] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the specific steps for determining the allowable disturbance range based on local dynamic compliance are as follows:

[0024] By utilizing the degree of trajectory offset disturbance, and based on the actual feed rate of each disturbed tool position and the distance from the disturbed tool position to the adjacent tool position along the machining trajectory, the frequency of the trajectory offset change per unit time is determined, and the equivalent excitation frequency of each disturbed tool position is obtained.

[0025] The equivalent excitation frequency of each disturbed tool position is matched with the degree of trajectory offset disturbance. The equivalent excitation frequency is used to characterize the speed of trajectory offset change, and the degree of trajectory offset disturbance is used to characterize the strength of offset change between adjacent tool positions. Then, the correlation is established according to the corresponding tool positions to obtain the trajectory correction excitation.

[0026] The excitation position of each disturbed tool position is corrected along the trajectory. The equivalent excitation frequency and the degree of vibration propagation are correlated. Combined with the local dynamic compliance of the corresponding tool position, the influence of the trajectory offset change on the vibration response of each tool position is calculated.

[0027] The baseline allowable upper limit of the trajectory offset disturbance is adjusted according to the influence of vibration response and local dynamic compliance. When the influence of vibration response increases, the baseline allowable upper limit is reduced. When local dynamic compliance increases, the adjusted allowable upper limit is further reduced. The allowable disturbance range of each tool position is determined by the final allowable upper limit.

[0028] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts described in this invention, when the trajectory offset disturbance exceeds the allowable disturbance range, the target trajectory offset amount exceeding the allowable disturbance range is distributed step-by-step along the unprocessed continuous tool positions. The specific steps are as follows:

[0029] According to the arrangement order of tool positions in the machining trajectory, the trajectory offset disturbance degree of each disturbed tool position is compared with the allowable disturbance range item by item. Tool positions whose trajectory offset disturbance degree exceeds the allowable disturbance range are screened out, and the segments that exceed the allowable disturbance range are identified. Then, the segments that exceed the allowable disturbance range are associated with the target trajectory offset amount, and the corresponding tool positions are identified as risk tool positions, thus obtaining the trajectory offset risk.

[0030] Locate each risk tool position from the trajectory offset risk, compare the target trajectory offset of the risk tool position with that of the adjacent tool position, extract the offset difference value that causes the trajectory offset disturbance to exceed the allowable disturbance range, and use the offset difference value as the offset amount to be released to be allocated step by step along the machining direction.

[0031] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts according to the present invention, the step of generating a locally corrected trajectory for the unmachined tool position, where the trajectory offset disturbance of each adjacent tool position is within the allowable disturbance range, is as follows:

[0032] Distribute the amount of offset to be released from near to far along the continuous tool positions that have not yet been processed. Take the maximum offset amount that each tool position can accept as the single-level distribution amount, and continue to transfer the remaining offset amount to the next tool position until all the offset amounts to be released are distributed and the degree of trajectory offset disturbance is within the allowable disturbance range, thus obtaining the restricted trajectory offset.

[0033] Based on the restricted trajectory offset, the redistributed trajectory offset is applied to the continuous tool positions that have not yet been machined, and the coordinates of the corresponding original tool positions are corrected in the opposite direction of the expected tool deflection direction. Then, each corrected tool position is connected according to the tool position arrangement order in the machining trajectory, and the two ends of the correction range are continuously connected with the adjacent uncorrected tool positions to generate a local correction trajectory for the unmachined tool positions.

[0034] As a preferred embodiment of the vibration identification and trajectory correction method for milling large-size parts described in this invention, the steps of controlling the tool position milling according to the locally corrected trajectory of the unmachined tool position, updating the material removal range based on the actual execution position, and then writing the updated tool position machining association information to form updated tool position machining association information are as follows:

[0035] Milling is performed according to the local correction trajectory of the unprocessed tool position. The actual position of the feed axis is continuously read and converted into the actual execution position of the tool. It is then matched with the corresponding tool position in the local correction trajectory of the unprocessed tool position. Adjacent actual execution positions are then connected to form the actual movement path of the tool, and the tool sweep range is redefined.

[0036] The new material removal range is determined by using the actual tool sweep range, and then the new material removal range is merged and updated with the existing material removal range. Finally, the tool position machining association information is written according to the actual execution position to form the updated tool position machining association information.

[0037] The beneficial effects of this invention are as follows: By combining the degree of trajectory offset disturbance, equivalent excitation frequency, vibration propagation degree, and local dynamic compliance to determine the vibration response influence, and adjusting the allowable disturbance range in the industrial control system accordingly, trajectory correction and tool position dynamic state matching are achieved, reducing the risk of local vibration caused by trajectory offset changes; by using the offset difference of the disturbance exceeding the limit as the offset to be released, and distributing it step by step along the continuous tool positions that have not yet been machined according to the maximum allowable offset, the industrial control system achieves decentralized correction of the over-limit trajectory offset, improving the continuity of tool deflection compensation and milling stability. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart for a vibration identification and trajectory correction method for milling large-size parts.

[0040] Figure 2 A flowchart for determining the dynamic state parameters of the tool position.

[0041] Figure 3 A flowchart for determining the degree of trajectory bias disturbance.

[0042] Figure 4 A flowchart for generating locally corrected machining trajectories. Detailed Implementation

[0043] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0045] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0046] Reference Figures 1-4This is one embodiment of the present invention, which provides a vibration identification and trajectory correction method for milling large-size parts, including the following steps:

[0047] S1. Collect actual tool position and vibration signal, determine the material removal range based on actual tool position and establish correlation to form tool position machining correlation information.

[0048] The actual tool position and vibration signal are collected, and each vibration sampling point is matched to the actual tool position at the corresponding time according to the collection time to determine the vibration signal of each actual tool position.

[0049] The specific process includes continuously acquiring the tool's position coordinates during machining from the feed axis position feedback information of the CNC machine tool, determining the actual tool position according to the machining trajectory, and simultaneously acquiring vibration signals from vibration sensors arranged on the spindle side and the workpiece side at a unified acquisition time. The acquisition time recorded at each vibration sampling point is compared with the actual tool position time item by item. Vibration sampling points with the same acquisition time or within the corresponding actual tool position time range are matched to the actual tool position. Then, the matched vibration sampling points are collected according to the actual tool position to determine the vibration signal of each actual tool position.

[0050] It should be noted that vibration signal refers to the continuous signal of spindle-side vibration and workpiece-side vibration collected during the milling process of large-size parts, which changes over time. The vibration signal includes the acquisition time, vibration amplitude, vibration direction, and corresponding frequency components of each vibration sampling point.

[0051] The tool sweep range is determined by the continuous movement segment of the actual tool position, and compared with the range of material that has not yet been removed to determine the material removal range. Then, the material removal range is correlated with the vibration signal to form tool position machining correlation information.

[0052] The specific process includes connecting adjacent actual tool positions according to their arrangement order, determining the range of positions traversed by the tool based on the positional changes between adjacent actual tool positions, sequentially connecting the positional ranges of each adjacent actual tool position to obtain the spatial range covered by the continuous movement segment of the tool along the actual tool position, and determining the covered spatial range as the tool sweep range. Then, the tool sweep range is compared position by position with the range of material that has not yet been removed, and the overlapping ranges are determined as the material removal range. The material removal range is associated with the corresponding vibration signal according to the actual tool position, and the corresponding content between the actual tool position, the material removal range, and the vibration signal is recorded to form tool position machining association information.

[0053] It should be noted that the tool position machining association information refers to the information formed by collecting the material removal range and vibration signal correspondence according to the actual tool position. Specifically, it includes each actual tool position, the vibration signal corresponding to each actual tool position, the material removal range corresponding to each actual tool position, the correspondence between the actual tool position and the vibration signal according to the acquisition time, and the positional correspondence between the actual tool position and the material removal range. It is used to characterize the material removal state and vibration state under different actual tool positions.

[0054] S2. Determine the reference local dynamic compliance of the current tool position based on the material removal range, and obtain the vibration propagation degree from the vibration signal to obtain the dynamic state parameters of the tool position.

[0055] Based on the material removal range, the local material action area of ​​the current tool position is determined. The percentage of unremoved material is counted to obtain the material retention degree. Then, the initial local dynamic compliance degree before machining at the current tool position is determined and corrected according to the material retention degree to obtain the baseline local dynamic compliance degree.

[0056] The specific process includes locating the material position corresponding to the current tool position based on the material removal range, determining the local material action area based on the area covered by the unremoved material near the current tool position, comparing the area of ​​unremoved material within the local material action area with the local material action area, determining the material retention degree according to the proportion of unremoved material, determining the initial local dynamic compliance degree before machining at the current tool position based on the pre-calibrated correspondence between the workpiece geometry, material properties, and local dynamic compliance degree, and then using the initial local dynamic compliance degree corresponding to the current tool position before machining as a benchmark, adjusting the initial local dynamic compliance degree according to the relationship that the displacement response of the local structure to external forces increases when the material retention degree decreases. The lower the material retention degree, the higher the initial local dynamic compliance degree, and the higher the material retention degree, the lower the adjustment range, thus obtaining the benchmark local dynamic compliance degree.

[0057] It should be noted that the baseline local dynamic compliance is used to characterize the ability of the local material action area to generate displacement response under the current material retention state, and serves as the basic parameter for determining the tool position compliance in conjunction with the degree of vibration propagation, and subsequently determining the expected tool deflection amount and the allowable disturbance range.

[0058] The vibration amplitudes of the spindle-side vibration and the workpiece-side vibration within the same characteristic frequency band are extracted from the vibration signal. The vibration amplitude changes are compared to determine the degree of vibration propagation. Then, the vibration amplitudes are aggregated with the reference local dynamic compliance according to the current tool position to obtain the tool position dynamic state parameters.

[0059] The specific process includes: determining the frequency range covered by the spindle-side vibration and workpiece-side vibration according to the vibration signal corresponding to the current tool position; defining the frequency range shared by the spindle-side vibration and workpiece-side vibration as the same characteristic frequency band; acquiring the vibration amplitude of the spindle-side vibration and the vibration amplitude of the workpiece-side vibration according to the frequency position within the same characteristic frequency band; comparing the spindle-side vibration amplitude and the workpiece-side vibration amplitude at the same frequency position to determine the change in the workpiece-side vibration amplitude relative to the spindle-side vibration amplitude; then, collecting the amplitude retention after the vibration is transmitted from the spindle side to the workpiece side according to the amplitude changes at each frequency position within the same characteristic frequency band; determining the degree of vibration propagation by the retention ratio of the workpiece-side vibration amplitude relative to the spindle-side vibration amplitude; a higher vibration amplitude retention ratio corresponds to a greater degree of vibration propagation, and a lower vibration amplitude retention ratio corresponds to a smaller degree of vibration propagation; finally, collecting the degree of vibration propagation and the reference local dynamic compliance according to the current tool position; recording the vibration propagation degree and the reference local dynamic compliance corresponding to the current tool position to obtain the tool position dynamic state parameters.

[0060] It should be noted that the vibration propagation degree is used to characterize the retention of vibration amplitude after it is transmitted from the spindle side to the workpiece side. The greater the vibration propagation degree, the smaller the attenuation of the vibration after it is transmitted from the spindle side to the workpiece side, and the stronger the vibration influence on the area corresponding to the current tool position. It is used to characterize the dynamic state of the current tool position in conjunction with the reference local dynamic compliance, and to provide a basis for correcting the reference local dynamic compliance, determining the tool position compliance, and the local dynamic compliance. The tool position dynamic state parameters refer to the set of parameters formed by aggregating the vibration propagation degree and the reference local dynamic compliance according to the current tool position. Specifically, it includes the vibration propagation degree and the reference local dynamic compliance corresponding to the current tool position. It is used to jointly characterize the dynamic response characteristics of the current tool position under the existing material retention state and vibration transmission state, and to serve as the basis for correcting the reference local dynamic compliance, determining the tool position compliance, and determining the local dynamic compliance along the unprocessed continuous tool positions.

[0061] S3. Using the dynamic state parameters of the tool position, the local dynamic compliance of the reference is corrected according to the degree of vibration propagation, and the local dynamic compliance is determined along the continuous tool positions that have not yet been machined. The expected tool deflection amount is determined by each local dynamic compliance and converted into the target trajectory offset amount. Then, the trajectory offset disturbance degree is determined by combining the difference of the target trajectory offset amount of adjacent tool positions with the tool position spacing. The allowable disturbance range is determined according to the local dynamic compliance. When the trajectory offset disturbance degree exceeds the allowable disturbance range, the target trajectory offset amount that exceeds the allowable disturbance range is distributed step by step along the continuous tool positions that have not yet been machined until the trajectory offset disturbance degree of each adjacent tool position is within the allowable disturbance range, thus generating the local corrected trajectory of the unmachined tool position.

[0062] By using the dynamic state parameters of the tool position, the vibration propagation degree of the previous adjacent tool position is obtained and compared with the vibration propagation degree of the current tool position to obtain the propagation deviation. Then, the reference local dynamic compliance is corrected according to the magnitude and direction of the propagation deviation to obtain the tool position compliance.

[0063] The specific process includes: using the tool position dynamic state parameters, comparing the vibration propagation degree of the current tool position with that of the previous adjacent tool position; subtracting the vibration propagation degree of the previous adjacent tool position from the current tool position's vibration propagation degree to obtain the propagation deviation; when the current tool position is the first tool position in the machining trajectory or the initial tool position that has not yet been machined, the previous adjacent tool position does not exist, and the vibration propagation degree of the current tool position is determined as the vibration propagation degree of the previous adjacent tool position, making the propagation deviation zero; determining the change amplitude of vibration propagation state between adjacent tool positions based on the absolute value of the propagation deviation; and obtaining the correlation between the absolute value of the propagation deviation calibrated in the historical milling test and the reference local dynamic compliance adjustment amount. Based on the corresponding relationship, the absolute value of the propagation deviation is substituted into the corresponding relationship, and the adjustment amount of the reference local dynamic compliance is calculated by linear interpolation. The direction of change of the vibration propagation degree is determined according to the sign of the propagation deviation. When the propagation deviation is positive, it indicates that the vibration propagation degree of the current tool position is increased relative to the previous adjacent tool position, and the reference local dynamic compliance is increased accordingly according to the adjustment amount. When the propagation deviation is negative, it indicates that the vibration propagation degree of the current tool position is decreased relative to the previous adjacent tool position, and the reference local dynamic compliance is decreased accordingly according to the adjustment amount. The larger the absolute value of the propagation deviation, the larger the adjustment amount of the reference local dynamic compliance. The adjusted reference local dynamic compliance is determined as the tool position compliance of the current tool position.

[0064] It should be noted that tool position compliance refers to a dynamic response parameter obtained by correcting the baseline local dynamic compliance after considering the changes in vibration propagation degree between the current tool position and the previous adjacent tool position. It is used to characterize the ability of the current tool position to generate a displacement response when subjected to external forces under actual vibration propagation conditions. The larger the tool position compliance, the easier it is for the current tool position to generate a displacement response.

[0065] Using the tool position compliance as the starting value, the spatial overlap area of ​​adjacent local material action areas is compared along the unprocessed continuous tool positions. The difference between the tool position compliance and the reference local dynamic compliance is gradually reduced according to the spatial overlap area and superimposed on the reference local dynamic compliance of each continuous tool position to form the local dynamic compliance.

[0066] The specific process includes: using the tool position compliance as the starting value for determining the local dynamic compliance of the unprocessed continuous tool positions; comparing the local material action areas corresponding to adjacent tool positions according to the tool position arrangement order in the machining trajectory; determining the part covered by the adjacent local material action areas as the spatial overlap area; determining the attenuation amplitude of the difference between the tool position compliance and the reference local dynamic compliance based on the size of the spatial overlap area; the larger the spatial overlap area, the smaller the attenuation amplitude of the difference; the smaller the spatial overlap area, the larger the attenuation amplitude of the difference; superimposing the attenuated difference to the reference local dynamic compliance of the next tool position to obtain the local dynamic compliance of the next tool position; continuing to attenuate the difference according to the spatial overlap area of ​​the next adjacent local material action area and superimposing it to the reference local dynamic compliance of the corresponding continuous tool position; processing sequentially along the unprocessed continuous tool positions to form the local dynamic compliance of each continuous tool position.

[0067] Based on the change in vibration amplitude at the current tool position, and combined with the local dynamic compliance of each consecutive tool position, the corresponding displacement response is obtained, and each displacement response is converted into the expected deflection amount for each consecutive tool position.

[0068] The specific process includes determining the magnitude of the vibration effect based on the change in vibration amplitude of the current tool position, and corresponding each tool position in the machining trajectory with the local dynamic compliance of each consecutive tool position. Based on the relationship that the displacement response generated by the same vibration amplitude change increases when the local dynamic compliance increases and decreases when the local dynamic compliance decreases, the displacement response generated by the same vibration amplitude change is determined when the vibration amplitude change acts on each consecutive tool position. The displacement amount corresponding to the displacement response of each consecutive tool position is taken as the expected deflection displacement of each consecutive tool position, and the expected deflection amount of each consecutive tool position is obtained.

[0069] It should be noted that the expected deflection amount refers to the expected displacement determined based on the change in vibration amplitude of the current tool position and the local dynamic compliance of each consecutive tool position. It is used to characterize the deflection displacement that each consecutive tool position may produce under the current vibration. The expected deflection amount serves as the basis for determining the target trajectory offset amount and is used to compensate for possible tool position offsets in advance, thereby reducing the impact of deflection on the machining trajectory accuracy.

[0070] The expected deflection amount of each consecutive tool position is matched with the direction of the largest vibration amplitude in the vibration signal and used as the expected deflection direction. Then, the expected deflection amount is mapped to the machining trajectory of the tool position in the opposite direction of the expected deflection direction to obtain the target trajectory offset amount of each consecutive tool position.

[0071] The specific process includes matching the expected deflection amount of each consecutive tool position with the vibration signal according to the corresponding tool position, comparing the vibration amplitude corresponding to different vibration directions in the vibration signal, determining the direction with the largest vibration amplitude as the expected deflection direction of each consecutive tool position, determining the spatial displacement direction of the expected deflection amount according to the expected deflection direction, using the reverse of the expected deflection direction as the trajectory correction direction, and then projecting the expected deflection amount along the trajectory correction direction onto the machining trajectory of the corresponding tool position according to the position of each consecutive tool position in the machining trajectory. The projected displacement is used as the trajectory offset that needs to be adjusted for the corresponding tool position. The trajectory offset is determined item by item according to the arrangement order of each consecutive tool position to obtain the target trajectory offset amount of each consecutive tool position.

[0072] It should be noted that the target trajectory offset refers to the trajectory correction displacement determined on the machining trajectory of the corresponding tool position based on the expected deflection amount and expected deflection direction of each consecutive tool position. It is used to characterize the amount of compensation that each consecutive tool position needs to perform in the opposite direction of the expected deflection direction. The target trajectory offset serves as the basis for judging the trajectory offset change and trajectory offset disturbance degree of adjacent tool positions, and is used to form the local correction trajectory of the unmachined tool position.

[0073] Compare the target trajectory offsets of each consecutive tool position, calculate the difference in target trajectory offsets between adjacent tool positions, and determine the offset changes between adjacent tool positions by combining the spacing of adjacent tool positions along the machining trajectory. Then, record each offset change according to the order of the tool positions in the machining trajectory to obtain the trajectory offset changes.

[0074] The specific process includes: according to the tool position arrangement order in the machining trajectory, comparing the target trajectory offset of each consecutive tool position with the target trajectory offset of the next adjacent tool position item by item; obtaining the difference in target trajectory offset between adjacent tool positions by using the magnitude of the change in target trajectory offset; then combining the difference in target trajectory offset between adjacent tool positions with the distance between adjacent tool positions along the machining trajectory; using the change in target trajectory offset corresponding to a unit tool position distance to characterize the offset change between adjacent tool positions; when the difference in target trajectory offset between adjacent tool positions increases or the distance between adjacent tool positions along the machining trajectory decreases, the offset change between adjacent tool positions increases accordingly; when the difference in target trajectory offset between adjacent tool positions decreases or the distance between adjacent tool positions along the machining trajectory increases, the offset change between adjacent tool positions decreases accordingly; and finally, recording the offset change between each adjacent tool position in sequence according to the tool position arrangement order in the machining trajectory to obtain the trajectory offset change.

[0075] The expression for calculating the difference in target trajectory offset between adjacent tool positions is:

[0076] ;

[0077] in, For the first The tool position and the first The difference in target trajectory offset between each tool position; For the first Target trajectory offset for each tool position; For the first Target trajectory offset for each tool position; This refers to the tool position number in the machining trajectory; This is the bias change correction factor; This is the bias correction value.

[0078] It should be noted that, It is determined based on the correspondence between the difference in target trajectory offset and the actual vibration response in historical milling tests, and is used to adjust the correction intensity of relative offset change, with an exemplary range of 0.2 to 0.8. It is determined based on the minimum effective resolution of the target trajectory offset or the minimum stable change value of the offset in historical processing, in order to avoid the correction ratio being abnormal due to the denominator being too small. An exemplary range is 0.001 to 0.01 mm.

[0079] Furthermore, before calculating the difference in target trajectory offset between adjacent tool positions, the target trajectory offset of each consecutive tool position is uniformly converted into a physical quantity in millimeters. The offset correction value is determined based on the minimum effective resolution of the target trajectory offset or the minimum stable change value of the offset in historical machining. The offset correction value is used to standardize the target trajectory offset to avoid the correction ratio being abnormal due to an excessively small denominator, thus ensuring that the parameters involved in calculating the difference in target trajectory offset between adjacent tool positions have a uniform physical dimension.

[0080] Based on the trajectory offset change, the offset change between adjacent tool positions is compared according to the tool position arrangement order in the machining trajectory. Tool positions with continuously increasing or sudden increases in offset change are identified as disturbed tool positions. The difference in offset change between the disturbed tool position and its adjacent tool positions is calculated to determine the degree of trajectory offset disturbance.

[0081] The specific process includes comparing the offset changes between adjacent tool positions one by one according to the tool position arrangement order in the machining trajectory, based on the trajectory offset change. When the number of tool positions with gradually increasing offset changes between adjacent tool positions reaches a preset consecutive tool position number threshold, the gradually increasing offset changes between multiple consecutive adjacent tool positions are determined as a continuously increasing state. When the increase in the offset change between a certain adjacent tool position relative to the offset change between the previous adjacent tool positions reaches a preset offset change increase threshold, the significantly increased offset change between a certain adjacent tool position relative to the previous adjacent tool position is determined as a sudden increase state, and the corresponding tool position is determined as a disturbed tool position. Then, the offset change corresponding to the disturbed tool position is compared with the offset change corresponding to the previous adjacent tool position to obtain the offset change difference. The magnitude of the offset change difference characterizes the strength of the sudden change in trajectory offset change at the disturbed tool position. The larger the offset change difference, the greater the degree of trajectory offset disturbance; the smaller the offset change difference, the smaller the degree of trajectory offset disturbance. The degree of trajectory offset disturbance is thus determined.

[0082] It should be noted that the trajectory offset disturbance degree refers to the parameter used to characterize the strength of the abrupt change in trajectory offset when the offset change between adjacent tool positions continuously increases or suddenly increases. The greater the trajectory offset disturbance degree, the more drastic the trajectory offset change between adjacent tool positions, and the easier it is to form a strong dynamic excitation during tool position movement. The trajectory offset disturbance degree is used to compare with the allowable disturbance range to determine whether the target trajectory offset amount needs to be redistributed, and serves as the basis for determining risky tool positions and generating local correction trajectories for unprocessed tool positions.

[0083] The expression for calculating the difference in offset change between the disturbed tool position and its adjacent tool positions is as follows:

[0084] ;

[0085] in, For the first The difference in offset change corresponding to each disturbed tool position; For the first The offset change between the perturbation tool position and the next adjacent tool position; The previous adjacent tool position and the first The offset change between the perturbation tool positions; This is the bias mutation correction coefficient.

[0086] It should be noted that, It is calibrated based on the correspondence between the difference in offset change and the actual vibration response in historical milling tests, and is used to adjust the enhancement amplitude of the mutation term, with an exemplary range of 0.1 to 0.6.

[0087] Furthermore, before calculating the offset variation difference between the disturbed tool position and its adjacent tool positions, the offset variation between each disturbed tool position and its adjacent tool positions is uniformly converted into a physical quantity in millimeters. The offset variation correction value is determined based on the minimum effective resolution of the offset variation or the minimum stable variation value of the offset variation in historical machining. The offset variation is standardized using the offset variation correction value to avoid the correction ratio being abnormal due to an excessively small denominator, thus ensuring that the parameters involved in calculating the offset variation difference between the disturbed tool position and its adjacent tool positions have a uniform physical dimension.

[0088] By utilizing the degree of trajectory offset disturbance, and based on the actual feed rate of each disturbed tool position and the distance from the disturbed tool position to the adjacent tool position along the machining trajectory, the frequency of the trajectory offset change per unit time is determined, thus obtaining the equivalent excitation frequency of each disturbed tool position.

[0089] The specific process includes locating each disturbed tool position using the degree of trajectory offset disturbance, determining the speed at which the tool position moves along the machining trajectory according to the actual feed rate of each disturbed tool position, and determining the time corresponding to the tool passing through the adjacent tool position by combining the distance between the disturbed tool position and the adjacent tool position along the machining trajectory. One trajectory offset change between adjacent tool positions is taken as one action process. The action frequency of trajectory offset change is determined according to the number of times the trajectory offset change occurs per unit time. The action frequency increases when the actual feed rate increases or the distance between the disturbed tool position and the adjacent tool position along the machining trajectory decreases, and decreases when the actual feed rate decreases or the distance between the disturbed tool position and the adjacent tool position along the machining trajectory increases. The action frequency is then determined as the equivalent excitation frequency of each disturbed tool position.

[0090] It should be noted that the equivalent excitation frequency refers to the number of times the trajectory offset change acts on the tool-workpiece system per unit time during the actual tool feed process, and is used to characterize the speed of the trajectory offset change.

[0091] The equivalent excitation frequency of each disturbed tool position is matched with the degree of trajectory offset disturbance. The equivalent excitation frequency is used to characterize the speed of trajectory offset change, and the degree of trajectory offset disturbance is used to characterize the strength of offset change between adjacent tool positions. Then, the correlation is established according to the corresponding tool positions to obtain the trajectory correction excitation.

[0092] The specific process includes: locating each disturbed tool position using the degree of trajectory offset disturbance; determining the speed at which each disturbed tool position moves along the machining trajectory based on its actual feed rate; determining the time corresponding to the tool passing through adjacent tool positions by combining the distance between each disturbed tool position and the adjacent tool position along the machining trajectory; taking one trajectory offset change between adjacent tool positions as one action process; determining the action frequency of trajectory offset change based on the number of trajectory offset changes per unit time; increasing the action frequency when the actual feed rate increases or the distance between each disturbed tool position and the adjacent tool position along the machining trajectory decreases, and decreasing the action frequency when the actual feed rate decreases or the distance between each disturbed tool position and the adjacent tool position along the machining trajectory increases; determining the action frequency as the equivalent excitation frequency of each disturbed tool position; matching the equivalent excitation frequency of each disturbed tool position with the degree of trajectory offset disturbance; using the equivalent excitation frequency to characterize the speed of trajectory offset change; using the degree of trajectory offset disturbance to characterize the strength of offset change between adjacent tool positions; and establishing a correlation according to the corresponding tool positions to obtain the trajectory correction excitation.

[0093] The excitation position of each disturbed tool position is corrected along the trajectory. The equivalent excitation frequency and the degree of vibration propagation are correlated. Combined with the local dynamic compliance of the corresponding tool position, the influence of trajectory offset change on the vibration response of each tool position is calculated.

[0094] The specific process includes: locating each disturbed tool position along the trajectory correction excitation; obtaining the vibration propagation degree and equivalent excitation frequency corresponding to each disturbed tool position from the vibration signal; establishing a correspondence according to the corresponding tool positions; simultaneously obtaining the local dynamic compliance degree corresponding to each disturbed tool position; averaging the initial local dynamic compliance degrees of each reference tool position before machining to obtain the local dynamic compliance benchmark value; calibrating and determining the frequency influence correction coefficient based on the correspondence between the change in equivalent excitation frequency and the change in vibration response influence in historical milling tests; averaging the equivalent excitation frequencies of each reference tool position under historical stable milling conditions to obtain the equivalent excitation frequency benchmark value; multiplying the vibration propagation degree of each disturbed tool position by the ratio of the local dynamic compliance degree to the local dynamic compliance benchmark value; and then combining the product of the frequency influence correction coefficient and the ratio of the equivalent excitation frequency to the equivalent excitation frequency benchmark value to obtain the influence of trajectory offset change on the vibration response of each tool position.

[0095] The expression for the influence of trajectory offset change on the vibration response of each tool position is:

[0096] ;

[0097] in, For the first The impact of vibration response on each tool position; For the first The degree of vibration propagation corresponding to each tool position; For the first Local dynamic compliance corresponding to each tool position; This serves as the baseline value for local dynamic compliance. This is a correction factor for the frequency effect; For the first The equivalent excitation frequency corresponding to each disturbed tool position; This is the equivalent excitation frequency reference value.

[0098] It should be noted that, It is obtained by averaging the initial local dynamic compliance of each reference tool position before machining, and serves as a unified benchmark for local dynamic compliance; It is determined based on the correspondence between the changes in the effective excitation frequency and the changes in the influence of vibration response in historical milling tests, and is used to adjust the intensity of the frequency term. An exemplary range is 0.1 to 0.5. It is determined by taking the average value of the equivalent excitation frequency of each reference tool position under historical stable milling conditions, and serves as a unified benchmark for the equivalent excitation frequency.

[0099] Furthermore, before calculating the impact of trajectory offset changes on the vibration response of each tool position, the vibration propagation degree, local dynamic compliance, local dynamic compliance benchmark value, equivalent excitation frequency, and equivalent excitation frequency benchmark value corresponding to each tool position are uniformly converted into standard physical dimensions. The local dynamic compliance is dimensionlessly processed using the local dynamic compliance benchmark value to obtain the compliance ratio, and the equivalent excitation frequency is dimensionlessly processed using the equivalent excitation frequency benchmark value to obtain the frequency ratio. This ensures that all parameters involved in calculating the impact of trajectory offset changes on the vibration response of each tool position have unified physical dimensions.

[0100] The baseline allowable upper limit of the trajectory offset disturbance is adjusted according to the influence of vibration response and local dynamic compliance. When the influence of vibration response increases, the baseline allowable upper limit is reduced. When local dynamic compliance increases, the adjusted allowable upper limit is further reduced. The allowable disturbance range of each tool position is determined by the final allowable upper limit.

[0101] The specific process includes: obtaining the baseline allowable upper limit of the maximum trajectory offset disturbance degree from historical milling tests; adjusting the baseline allowable upper limit of the trajectory offset disturbance degree using the influence of the vibration response corresponding to each tool position and the local dynamic compliance corresponding to each tool position; analyzing the changes in the influence of the vibration response corresponding to each tool position; when the influence of the vibration response increases, reducing the baseline allowable upper limit of the trajectory offset disturbance degree according to the increase in the influence of the vibration response to obtain the adjusted allowable upper limit; analyzing the changes in the local dynamic compliance corresponding to each tool position; when the local dynamic compliance increases, further reducing the adjusted allowable upper limit based on the increase in the local dynamic compliance to obtain the final allowable upper limit; and determining the allowable disturbance range of each tool position using the final allowable upper limit.

[0102] It should be noted that the upper limit of the baseline is an initial allowable value determined based on the maximum trajectory offset disturbance level calibrated in historical milling tests. It is used as a baseline for adjusting the allowable disturbance range of each tool position by combining the influence of vibration response and local dynamic compliance.

[0103] According to the arrangement order of tool positions in the machining trajectory, the trajectory offset disturbance degree of each disturbed tool position is compared with the allowable disturbance range item by item. Tool positions whose trajectory offset disturbance degree exceeds the allowable disturbance range are screened out, and the segments exceeding the allowable disturbance range are identified. Then, the segments exceeding the allowable disturbance range are associated with the target trajectory offset amount, and the corresponding tool positions are identified as risk tool positions, thus obtaining the trajectory offset risk.

[0104] The specific process includes comparing the trajectory offset disturbance degree of each disturbed tool position with the corresponding allowable disturbance range according to the tool position arrangement order in the machining trajectory. When the trajectory offset disturbance degree of the disturbed tool position is greater than the allowable disturbance range, it is determined that the trajectory offset disturbance degree of the disturbed tool position exceeds the allowable disturbance range. Disturbed tool positions with trajectory offset disturbance degrees exceeding the allowable disturbance range are selected. The machining trajectory positions corresponding to the disturbed tool positions with trajectory offset disturbance degrees exceeding the allowable disturbance range are determined as segments exceeding the allowable disturbance range. The target trajectory offset amount corresponding to the segments exceeding the allowable disturbance range is obtained. The segments exceeding the allowable disturbance range are associated with the corresponding target trajectory offset amounts. Disturbed tool positions with trajectory offset disturbance degrees exceeding the allowable disturbance range are determined as risk tool positions. The correlation between each risk tool position, the corresponding segments exceeding the allowable disturbance range, and the target trajectory offset amount is summarized to obtain the trajectory offset risk.

[0105] It should be noted that trajectory bias risk refers to the set of risk information formed when the degree of trajectory bias disturbance exceeds the allowable disturbance range, including the correlation between the risk position, the corresponding over-limit section, and the target trajectory bias amount corresponding to the section.

[0106] Locate each risk tool position from the trajectory offset risk, compare the target trajectory offset of the risk tool position with that of the adjacent tool position, extract the offset difference value that causes the trajectory offset disturbance to exceed the allowable disturbance range, and use the offset difference value as the offset amount to be released to be allocated step by step along the machining direction.

[0107] The specific process includes locating each risk tool position from the trajectory offset risk, comparing the target trajectory offset of each risk tool position with the target trajectory offset of its adjacent tool positions in the machining trajectory according to the tool position arrangement order in the machining trajectory, obtaining the offset difference value, determining whether the offset difference value causes the trajectory offset disturbance to exceed the allowable disturbance range of each risk tool position, and extracting the offset difference value that causes the trajectory offset disturbance to exceed the allowable disturbance range of each risk tool position when the offset difference value causes the trajectory offset disturbance to exceed the allowable disturbance range of each risk tool position. The extracted offset difference value is determined as the offset to be released, and the offset to be released is used as the offset to be released to be allocated step by step along the machining direction.

[0108] It should be noted that the offset to be released is the offset difference that causes the trajectory offset disturbance to exceed the allowable disturbance range. It is used to distribute the excess trajectory offset step by step along the continuous tool positions that have not yet been machined in order to disperse the excess trajectory offset, thereby realizing the dispersed correction of the excess trajectory offset and improving the continuity of tool deflection compensation and milling stability.

[0109] Distribute the amount of offset to be released from near to far along the continuous tool positions that have not yet been processed. Take the maximum offset amount that each tool position can accept as the single-level distribution amount, and continue to transfer the remaining offset amount to the next tool position until all the amount of offset to be released is distributed and the degree of trajectory offset disturbance is within the allowable disturbance range, thus obtaining the restricted trajectory offset.

[0110] The specific process includes: determining the allocation order of unprocessed consecutive tool positions from near to far according to the tool position arrangement order in the machining trajectory; obtaining the maximum allowable offset amount for each tool position from the offset amount to be released; using the maximum allowable offset amount for each tool position as the single-stage allocation amount; comparing the offset amount to be released with the single-stage allocation amount; when the offset amount to be released is greater than the single-stage allocation amount, allocating the single-stage allocation amount to the current tool position; obtaining the remaining offset amount by the difference between the offset amount to be released and the single-stage allocation amount; and continuing to pass the remaining offset amount to the next tool position. The process of comparing the offset to be released with the single-level allocation amount is repeated for the current tool position until all the offset to be released is allocated. When the offset to be released is less than or equal to the single-level allocation amount, all the offset to be released is allocated to the current tool position. During the allocation process, the trajectory offset disturbance degree of each tool position is obtained. It is determined whether the trajectory offset disturbance degree of each tool position is within the allowable disturbance range. When the trajectory offset disturbance degree of each tool position is within the allowable disturbance range, the allocation stops. The offset to be released obtained from the allocation of each tool position is summarized to obtain the restricted trajectory offset.

[0111] Based on the restricted trajectory offset, the redistributed trajectory offset is applied to the continuous tool positions that have not yet been machined, and the coordinates of the corresponding original tool positions are corrected in the opposite direction of the expected tool deflection direction. Then, each corrected tool position is connected according to the tool position arrangement order in the machining trajectory, and the two ends of the correction range are continuously connected with the adjacent uncorrected tool positions to generate a local correction trajectory for the unmachined tool positions.

[0112] The specific process includes: obtaining the redistributed trajectory offset based on the restricted trajectory offset; applying the redistributed trajectory offset to the unprocessed continuous tool positions; comparing the vibration amplitudes corresponding to different vibration directions from the vibration signal; determining the direction with the largest vibration amplitude as the expected deflection direction for the unprocessed continuous tool positions; determining the trajectory correction direction along the opposite direction of the expected deflection direction; applying the redistributed trajectory offset along the trajectory correction direction to the original tool position coordinates of the unprocessed continuous tool positions to obtain the corrected tool position coordinates; determining the tool position with the corrected tool position coordinates as the corrected tool position; connecting each corrected tool position according to the tool position arrangement order in the machining trajectory to form a correction range; obtaining the endpoint positions at both ends of the correction range; obtaining the adjacent uncorrected tool positions corresponding to the endpoint positions; and continuously connecting the two ends of the correction range with the adjacent uncorrected tool positions to generate a local correction trajectory for the unprocessed tool positions.

[0113] S4. Control the tool position milling according to the local correction trajectory of the unprocessed tool position, update the material removal range according to the actual execution position, and then write the tool position machining association information to form the updated tool position machining association information.

[0114] Milling is performed according to the local correction trajectory of the unprocessed tool position. The actual position of the feed axis is continuously read and converted into the actual execution position of the tool. It is then matched with the corresponding tool position in the local correction trajectory of the unprocessed tool position, and adjacent actual execution positions are connected to form the actual movement path of the tool. The tool sweep range is then redefined.

[0115] The specific process includes: controlling the tool to move along the local correction trajectory of the unprocessed tool position for milling according to the arrangement order of each correction tool position in the local correction trajectory of the unprocessed tool position; continuously reading the actual position of the feed axis from the feed axis position feedback information of the CNC machine tool according to the acquisition time; converting the actual position of the feed axis to machine tool kinematic coordinates to obtain the actual execution position of the tool tip in the workpiece coordinate system; matching the actual execution position of the tool with the corresponding tool position in the local correction trajectory of the unprocessed tool position item by item according to the acquisition time to determine the tool position in the local correction trajectory of the unprocessed tool position corresponding to each actual execution position of the tool; connecting adjacent actual execution positions of the tool according to the acquisition time order to form the actual movement path of the tool; determining the position range traversed by the tool according to the position change between adjacent actual execution positions of the tool in the actual movement path; sequentially connecting the position ranges corresponding to each adjacent actual execution position of the tool to obtain the spatial range covered by the actual movement path of the tool; and redefining the covered spatial range as the tool sweep range.

[0116] The new material removal range is determined by using the actual tool sweep range, and then the new material removal range is merged and updated with the existing material removal range. Finally, the tool position machining association information is written according to the actual execution position to form the updated tool position machining association information.

[0117] The specific process includes: obtaining the area of ​​material that has not yet been removed using the actual tool sweeping range; comparing the actual tool sweeping range with the area of ​​material that has not yet been removed position by position according to spatial location to determine whether there is spatial overlap between the actual tool sweeping range and the area of ​​material that has not yet been removed; determining the spatial range where the actual tool sweeping range and the area of ​​material that has not yet been removed overlap as the new material removal range; obtaining the existing material removal range from the tool position machining association information; spatially aggregating the new material removal range and the existing material removal range to obtain the updated material removal range; associating the updated material removal range with each actual execution position and the corresponding vibration signal; and summarizing the correspondence between each actual execution position and the updated material removal range and the corresponding vibration signal to form the updated tool position machining association information.

[0118] In summary, this invention achieves trajectory correction and tool position dynamic state matching by: determining the vibration response influence amount by combining the trajectory offset disturbance degree, equivalent excitation frequency, vibration propagation degree, and local dynamic compliance, and adjusting the allowable disturbance range in the industrial control system accordingly, thereby reducing the risk of local vibration caused by trajectory offset changes; and by using the offset difference of the disturbance exceeding the limit as the offset amount to be released, and distributing it step by step along the unprocessed continuous tool positions according to the maximum allowable offset amount, the industrial control system achieves decentralized correction of the over-limit trajectory offset, improving the continuity of tool deflection compensation and milling stability.

[0119] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A vibration identification and trajectory correction method for milling large-size parts, characterized in that, include: Collect actual tool position and vibration signal, determine the material removal range based on actual tool position and establish correlation to form tool position machining correlation information; The reference local dynamic compliance of the current tool position is determined based on the material removal range, and the degree of vibration propagation is obtained from the vibration signal to obtain the dynamic state parameters of the tool position. Using the dynamic state parameters of the tool position, the baseline local dynamic compliance is corrected according to the degree of vibration propagation, and the local dynamic compliance is determined along the continuous tool positions that have not yet been machined. The expected tool deflection amount is determined by each local dynamic compliance and converted into the target trajectory offset amount. Then, the trajectory offset disturbance degree is determined by combining the difference of the target trajectory offset amount of adjacent tool positions with the tool position spacing. The allowable disturbance range is determined according to the local dynamic compliance. When the trajectory offset disturbance degree exceeds the allowable disturbance range, the target trajectory offset amount that exceeds the allowable disturbance range is distributed step by step along the continuous tool positions that have not yet been machined until the trajectory offset disturbance degree of each adjacent tool position is within the allowable disturbance range, thus generating the local corrected trajectory of the unmachined tool position. The tool position is controlled for milling according to the local correction trajectory of the unprocessed tool position, and the material removal range is updated according to the actual execution position and then written into the tool position machining association information to form the updated tool position machining association information.

2. The vibration identification and trajectory correction method for milling large-size parts as described in claim 1, characterized in that, The specific steps for determining the material removal range and establishing correlation relationships to form tool position machining correlation information are as follows: Collect actual tool position and vibration signal, match each vibration sampling point to the actual tool position at the corresponding time according to the collection time, and determine the vibration signal of each actual tool position; The tool sweep range is determined by the continuous movement segment of the actual tool position, and compared with the range of material that has not yet been removed to determine the material removal range. Then, the material removal range is correlated with the vibration signal to form tool position machining correlation information.

3. The vibration identification and trajectory correction method for milling large-size parts as described in claim 1 or 2, characterized in that, The specific steps for determining the reference local dynamic compliance of the current tool position and obtaining the vibration propagation degree from the vibration signal to obtain the dynamic state parameters of the tool position are as follows: Based on the material removal range, determine the local material action area of ​​the current tool position, calculate the percentage of unremoved material to obtain the material retention degree, then determine the initial local dynamic compliance degree before machining at the current tool position, and correct it according to the material retention degree to obtain the baseline local dynamic compliance degree; The vibration amplitudes of the spindle-side vibration and the workpiece-side vibration within the same characteristic frequency band are extracted from the vibration signal. The vibration amplitude changes are compared to determine the degree of vibration propagation. Then, the vibration amplitudes are aggregated with the reference local dynamic compliance according to the current tool position to obtain the tool position dynamic state parameters.

4. The vibration identification and trajectory correction method for milling large-size parts as described in claim 3, characterized in that, The specific steps for correcting the baseline local dynamic compliance according to the degree of vibration propagation and determining the local dynamic compliance along the unprocessed continuous tool path are as follows: By using the dynamic state parameters of the tool position, the vibration propagation degree of the previous adjacent tool position is obtained and compared with the vibration propagation degree of the current tool position to obtain the propagation deviation. Then, the reference local dynamic compliance is corrected according to the magnitude and direction of the propagation deviation to obtain the tool position compliance. Using the tool position compliance as the starting value, the spatial overlap area of ​​adjacent local material action areas is compared along the unprocessed continuous tool positions. The difference between the tool position compliance and the reference local dynamic compliance is gradually reduced according to the spatial overlap area and superimposed on the reference local dynamic compliance of each continuous tool position to form the local dynamic compliance.

5. The vibration identification and trajectory correction method for milling large-size parts as described in claim 1 or 4, characterized in that, The specific steps for determining the expected tool deflection amount from each local dynamic compliance and converting it into the target trajectory offset are as follows: Based on the change in vibration amplitude at the current tool position, and combined with the local dynamic compliance of each consecutive tool position, the corresponding displacement response is obtained, and each displacement response is converted into the expected deflection amount for each consecutive tool position. The expected deflection amount of each consecutive tool position is matched with the direction of the largest vibration amplitude in the vibration signal and used as the expected deflection direction. Then, the expected deflection amount is mapped to the machining trajectory of the tool position in the opposite direction of the expected deflection direction to obtain the target trajectory offset amount of each consecutive tool position.

6. The vibration identification and trajectory correction method for milling large-size parts as described in claim 5, characterized in that, The determination of the trajectory offset disturbance level by combining the difference in target trajectory offset between adjacent tool positions with the tool position spacing involves the following specific steps: Compare the target trajectory offsets of each consecutive tool position, calculate the difference in target trajectory offsets between adjacent tool positions, and determine the offset change between adjacent tool positions by combining the spacing of adjacent tool positions along the machining trajectory. Then, record each offset change according to the order of the tool positions in the machining trajectory to obtain the trajectory offset change. Based on the trajectory offset change, the offset change between adjacent tool positions is compared according to the tool position arrangement order in the machining trajectory. Tool positions with continuously increasing or sudden increases in offset change are identified as disturbed tool positions. The difference in offset change between the disturbed tool position and its adjacent tool positions is calculated to determine the degree of trajectory offset disturbance.

7. The vibration identification and trajectory correction method for milling large-size parts as described in claim 6, characterized in that, The specific steps for determining the allowable disturbance range based on local dynamic compliance are as follows: By utilizing the degree of trajectory offset disturbance, and based on the actual feed rate of each disturbed tool position and the distance from the disturbed tool position to the adjacent tool position along the machining trajectory, the frequency of the trajectory offset change per unit time is determined, and the equivalent excitation frequency of each disturbed tool position is obtained. The equivalent excitation frequency of each disturbed tool position is matched with the degree of trajectory offset disturbance. The equivalent excitation frequency is used to characterize the speed of trajectory offset change, and the degree of trajectory offset disturbance is used to characterize the strength of offset change between adjacent tool positions. Then, the correlation is established according to the corresponding tool positions to obtain the trajectory correction excitation. The excitation position of each disturbed tool position is corrected along the trajectory. The equivalent excitation frequency and the degree of vibration propagation are correlated. Combined with the local dynamic compliance of the corresponding tool position, the influence of the trajectory offset change on the vibration response of each tool position is calculated. The baseline allowable upper limit of the trajectory offset disturbance is adjusted according to the influence of vibration response and local dynamic compliance. When the influence of vibration response increases, the baseline allowable upper limit is reduced. When local dynamic compliance increases, the adjusted allowable upper limit is further reduced. The allowable disturbance range of each tool position is determined by the final allowable upper limit.

8. The vibration identification and trajectory correction method for milling large-size parts as described in claim 6 or 7, characterized in that, When the trajectory offset disturbance exceeds the allowable disturbance range, the target trajectory offset amount exceeding the allowable disturbance range is distributed step by step along the continuous tool positions that have not yet been processed. The specific steps are as follows: According to the arrangement order of tool positions in the machining trajectory, the trajectory offset disturbance degree of each disturbed tool position is compared with the allowable disturbance range item by item. Tool positions whose trajectory offset disturbance degree exceeds the allowable disturbance range are screened out, and the segments that exceed the allowable disturbance range are identified. Then, the segments that exceed the allowable disturbance range are associated with the target trajectory offset amount, and the corresponding tool positions are identified as risk tool positions, thus obtaining the trajectory offset risk. Locate each risk tool position from the trajectory offset risk, compare the target trajectory offset of the risk tool position with that of the adjacent tool position, extract the offset difference value that causes the trajectory offset disturbance to exceed the allowable disturbance range, and use the offset difference value as the offset amount to be released to be allocated step by step along the machining direction.

9. The vibration identification and trajectory correction method for milling large-size parts as described in claim 8, characterized in that, The process continues until the trajectory offset disturbance of each adjacent tool position is within the allowable disturbance range, generating a locally corrected trajectory for the unmachined tool position. The specific steps are as follows: Distribute the amount of offset to be released from near to far along the continuous tool positions that have not yet been processed. Take the maximum offset amount that each tool position can accept as the single-level distribution amount, and continue to transfer the remaining offset amount to the next tool position until all the amount of offset to be released is distributed and the degree of trajectory offset disturbance is within the allowable disturbance range, thus obtaining the restricted trajectory offset. Based on the restricted trajectory offset, the redistributed trajectory offset is applied to the continuous tool positions that have not yet been machined, and the coordinates of the corresponding original tool positions are corrected in the opposite direction of the expected tool deflection direction. Then, each corrected tool position is connected according to the tool position arrangement order in the machining trajectory, and the two ends of the correction range are continuously connected with the adjacent uncorrected tool positions to generate a local correction trajectory for the unmachined tool positions.

10. The vibration identification and trajectory correction method for milling large-size parts as described in claim 9, characterized in that, The steps for controlling the tool position milling according to the local correction trajectory of the unprocessed tool position, updating the material removal range based on the actual execution position, and then writing the updated tool position machining association information are as follows: Milling is performed according to the local correction trajectory of the unprocessed tool position. The actual position of the feed axis is continuously read and converted into the actual execution position of the tool. It is then matched with the corresponding tool position in the local correction trajectory of the unprocessed tool position. Adjacent actual execution positions are then connected to form the actual movement path of the tool, and the tool sweep range is redefined. The new material removal range is determined by using the actual tool sweep range, and then the new material removal range is merged and updated with the existing material removal range. Finally, the tool position machining association information is written according to the actual execution position to form the updated tool position machining association information.

Images