Extrusion thread trimming self-adaptive control method, extrusion thread system and application

Abstract

The invention discloses an extrusion thread trimming self-adaptive control method, an extrusion thread system and application. The extrusion thread trimming self-adaptive control method comprises the steps that workpiece material information and extrusion force historical data are obtained, a spindle no-load power waveform is collected, energy baseline parameters are extracted, and a crest residual height initial threshold value and a hardened layer thickness initial threshold value are determined; setting a radial compensation amount according to an initial threshold value, executing micro cutting, and analyzing a cutting process power waveform to obtain energy characteristic data; crest residual height data and hardened layer thickness data are obtained from the whole circumference of the thread, correction is carried out by combining the energy characteristic data, and evaluation data are generated; executing a threshold value updating algorithm, and outputting a new threshold value and a tooth repairing instruction; and calling a tooth repairing instruction to complete segmented trace cutting or calendaring treatment, and confirming that the index meets the updated threshold value. According to the scheme, double-index accurate control and dynamic balance of the tooth crest residual height and the hardened layer thickness can be achieved, the problem that a traditional fixed parameter method cannot adapt to workpiece differences is solved, and the machining quality and consistency are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision thread machining control, and particularly relates to an extrusion thread tooth repair adaptive control method, device, equipment and storage medium. BACKGROUND

[0002] Extrusion thread is an advanced internal thread forming process. A special extrusion tap is used to apply radial extrusion force on the preformed hole wall material, so that the metal material flows plastically to form a thread tooth profile. Compared with the traditional cutting thread process, the extrusion thread does not produce cutting chips during the forming process, and the extrusion effect causes cold work hardening effect on the thread surface, forming a continuous and dense hardened layer on the tooth top and tooth side, which significantly improves the fatigue resistance and wear resistance of the thread.

[0003] However, the plastic flow characteristics of the extrusion forming process inevitably produce small burrs and metal roll-over phenomenon on the thread tooth top, which will cause the thread fitting accuracy to decrease, the assembly torque to fluctuate, and even the fitting to be stuck. The existing technology generally uses a tooth repair process to solve this problem, that is, after extrusion is completed, a cutting tap is used to cut and trim the tooth top to remove burrs and correct the thread size. However, the cutting tooth repair process will inevitably cut off part of the surface layer material, and the thickness of the hardened layer formed by extrusion is usually only a few microns to tens of microns. The traditional fixed cutting depth method can easily completely cut off the entire hardened layer, thereby losing the strengthening effect brought by the extrusion process. In addition, since the material flow during the extrusion process is random, the burr distribution and hardened layer thickness at different positions and different workpieces are significantly different, and the existing tooth repair process cannot be personalized adjusted according to the actual state of each specific workpiece, resulting in either incomplete burr removal affecting assembly quality or excessive cutting damaging the performance of the hardened layer.

[0004] Therefore, how to accurately control and dynamically balance the two micron-level key indicators of tooth top residual height and extrusion hardened layer residual thickness during the extrusion thread tooth repair process has become a core technical problem restricting the further development and application of extrusion thread technology. SUMMARY

[0005] The main purpose of the present application is to solve the following technical problem: how to simultaneously quantify the tooth top residual height and the extrusion hardened layer residual thickness online during the extrusion thread tooth repair process and adaptively adjust the tooth repair path according to the quantification result, so as to dynamically balance the two micron-level indicators which are mutually restrictive within a single piece machining window.

[0006] In a first aspect, in order to solve the above technical problem, the present application provides an extrusion thread tooth repair adaptive control method, comprising: acquiring material information and extrusion force history data of a workpiece to be machined, collecting a main shaft no-load power waveform and extracting energy baseline parameters, and determining a tooth top residual height initial threshold value and a hardened layer thickness initial threshold value; According to the initial threshold value, a radial compensation amount is set and a micro-cutting is performed, and meanwhile, a cutting process power waveform is analyzed to obtain energy characteristic data; After the micro-cutting, crest residual height data and hardening layer thickness data are obtained respectively for the whole thread, and the energy characteristic data is combined for correction to generate evaluation data containing residual height peak value, thinnest hardening layer thickness and angular position information; According to the evaluation data, a threshold value updating algorithm is executed to output a new crest residual height threshold value, a hardening layer thickness threshold value and a tooth repair instruction containing a radial compensation amount and an angular section compensation path; The tooth repair instruction is called to complete segmented micro-cutting or polishing processing, and the crest residual height data and the hardening layer thickness data are obtained again to confirm that the two indicators meet the updated threshold value.

[0007] In the second aspect, the application provides an extrusion thread system adopting the extrusion thread tooth repair adaptive control method.

[0008] In the third aspect, the application provides an application of an extrusion thread, which adopts the extrusion thread tooth repair adaptive control method.

[0009] The technical scheme provided by the embodiments of the application starts from obtaining material information and extrusion force historical data of a workpiece to be processed, and these basic information can reflect the distribution characteristics of a hardening layer and the formation rule of burrs of the workpiece in the extrusion forming process. By collecting a main shaft no-load power waveform and extracting energy baseline parameters, the system establishes an energy reference benchmark in the current machining environment, which lays a foundation for subsequent cutting state monitoring. The initial threshold values of the crest residual height and the hardening layer thickness determined in combination with these information are no longer empirical fixed values, but personalized parameters based on specific workpiece characteristics, which avoids the adaptability problem caused by the one-size-fits-all method from the source.

[0010] During the subsequent micro-cutting process, the system synchronously carries out double monitoring: on the one hand, the radial compensation amount is controlled according to the initial threshold value to control the cutting depth, and on the other hand, the power waveform change in the cutting process is analyzed in real time. The power waveform contains rich material cutting information. When the cutting edge cuts into the base material from the hardened layer, the hardness difference between the two materials will produce characteristic changes in the power signal. These energy characteristic data provide process feedback information for subsequent accurate control. After the cutting is completed, the thread top residual height data and the hardened layer thickness data are obtained respectively around the whole thread, and are corrected in combination with the aforementioned energy characteristic data. Due to the differences in extrusion states at different angular positions, simple geometric detection may have errors, and the energy signal can verify the reliability of the detection results. The evaluation data generated through multi-dimensional information fusion is more accurate and reliable. Based on these evaluation data, the system executes a threshold updating algorithm, dynamically adjusts the control target, and generates a thread repair instruction containing the radial compensation amount and the angular section compensation path. This spatially differentiated compensation strategy can accurately process different regions according to their specific conditions, avoiding local overcutting or undercutting caused by traditional uniform thread repair. The segmented micro-cutting or polishing process is completed by calling the thread repair instruction, and the data is obtained again to confirm that the indicators meet the updated threshold. The whole control process forms a closed loop, ensuring the reliability and consistency of the machining results. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Figure 1 is a schematic diagram of an embodiment of the thread extrusion thread repair adaptive control method in the embodiments of the present application; Figure 2 Figure 2 is a schematic diagram of the cutting tap structure of the thread extrusion system in the embodiments of the present application; Figure 3 Figure 3 is a schematic diagram of the thread top of the thread extrusion thread repair adaptive control method in the embodiments of the present application; Figure 2 Figure 4 is an enlarged view of A in Figure 3; Figure 4 Figure 5 is a metallographic diagram of the thread of the workpiece to be machined (the thread has not been repaired before the thread top).

[0012] BRIEF DESCRIPTION OF DRAWINGS 1, connecting section; 2, cutting section; 21, chip removal surface; 211, chip removal groove; 22, thread surface; 221, cutting thread part. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0014] Extruded thread is an advanced internal thread forming process, which forms thread profile by applying radial extrusion force on the preformed hole wall material with a special extrusion tap, so that the metal material plastically flows. The uniqueness of this forming method is that the plastic deformation in the extrusion process will refine the grain size of the thread surface material and produce work hardening effect, forming a continuous hardened layer with a thickness of only a few microns to tens of microns on the crest and flank surface. This hardened film significantly improves the fatigue resistance and wear resistance of the thread, making it irreplaceable in high-performance application fields such as aerospace and automotive manufacturing. However, the plastic flow characteristics of the material during the extrusion forming process inevitably produce small burrs and metal rollover on the thread crest, as shown in FIG. 1, which will cause the thread fit accuracy to decrease, the assembly torque to fluctuate, and even the fit to be stuck, so the burrs must be removed and the thread size must be corrected by the thread repair process. Figure 4

[0015] The prior art generally uses cutting taps to repair the thread after extrusion, but this method faces a fundamental technical contradiction: the cutting repair process will inevitably cut off part of the surface layer material, and the thickness of the hardened layer formed by extrusion is extremely thin and unevenly distributed. The traditional fixed cutting depth method can easily cut off the entire hardened layer, thereby losing the strengthening effect brought by the extrusion process. More complex is that due to the randomness and complexity of material flow during the extrusion process, the burr distribution and hardened layer thickness at different positions and different workpieces are significantly different, and the existing thread repair process lacks the ability to make individual adjustments according to the actual state of each specific workpiece, resulting in either incomplete burr removal affecting assembly quality or excessive cutting damaging the performance of the hardened layer. This technical contradiction between "hardened layer protection and burr removal" and the adaptability problem between "fixed parameters and workpiece differences" has become a key bottleneck restricting the further development and popularization of extruded thread technology, therefore, the present application proposes an extruded thread repair self-adaptive control method to solve the above problems.

[0016] The extruded thread repair self-adaptive control method of the present embodiment can specifically include: Please refer to Figure 1 , obtain the material information and extrusion force history data of the workpiece to be processed, collect the no-load power waveform of the spindle and extract the energy baseline parameters, determine the initial threshold of the crest residual height and the initial threshold of the hardened layer thickness; ​Specifically, the material information of the workpiece to be processed and the extrusion force history data are obtained by reading the process record card attached to the workpiece, which records the material grade (such as 7075 aluminum alloy), heat treatment state (such as T6 state) and peak torque data during extrusion forming of the workpiece. The extrusion torque is continuously measured by a torque sensor installed on the main shaft of the extrusion tap during the entire extrusion process, and the recorded peak torque appears at the position of the middle thread circle with the maximum extrusion resistance, which reflects the overall extrusion forming strength level of the threaded hole. Although the hardening layer thickness of different thread circles is different, the peak torque can represent the overall material deformation degree and average hardening layer formation state of the threaded hole. The main shaft no-load power waveform acquisition is to let the main shaft with the assembled tap rotate at the same speed as the subsequent tooth repair in the state of not contacting the workpiece, and continuously collect the power consumption data of the main shaft motor through the power analyzer. The energy baseline parameters are obtained by statistical analysis of the no-load power data, including the power average value (reflecting the basic load of the equipment) and the standard deviation of the power fluctuation (reflecting the system stability), which establishes the power baseline under the current equipment state. The initial threshold value is determined by matching the material properties, and the system looks up the corresponding threshold value in the preset parameter table according to the yield strength grade and extrusion torque value of the material. This parameter table is established through statistical analysis of a large number of test data under different materials and extrusion conditions, ensuring the scientificity of the threshold setting. This individualized threshold setting method based on the actual material properties and forming state of the workpiece solves the problem that the traditional fixed parameters cannot adapt to the differences in characteristics of different workpieces, ensuring the accuracy and pertinence of the double-index control in the subsequent tooth repair process.

[0017] Please continue to refer to Figure 1 , set the radial compensation amount according to the initial threshold value and perform micro cutting, while analyzing the power waveform during cutting to obtain energy characteristic data; In an embodiment of the present application, setting the radial compensation amount according to the initial threshold value and performing micro cutting, while analyzing the power waveform during cutting to obtain energy characteristic data, comprises: According to the numerical relationship between the initial threshold value of the tooth crest residual height and the initial threshold value of the hardening layer thickness, a safety margin coefficient of the radial compensation amount is calculated, and the radial compensation amount is determined based on the safety margin coefficient and micro cutting is performed, and the main shaft power waveform during cutting is synchronously collected to obtain a time domain power signal; The Hilbert transform is performed on the time domain power signal to extract an envelope curve, a material conversion feature point reflecting the change of the hardening layer cutting state in the envelope curve is identified, an envelope peak factor corresponding to the material conversion feature point is calculated, and a first energy characteristic parameter is obtained; The time domain power signal is subjected to power spectrum analysis, a power spectrum slope is calculated, and the power spectrum slope is segmented and corrected according to the material conversion feature point to obtain a second energy feature parameter. The first energy feature parameter and the second energy feature parameter are combined to generate energy feature data.

[0018] The following specifically describes the steps involved in the above embodiments: In the process of thread extrusion tooth repair, the safety margin coefficient is a safety control factor calculated according to the double threshold value relationship, which is used to prevent excessive cutting damage to the hardened layer. In specific implementation, the numerical control system reads the pre-set initial threshold value of the tooth crest residual height and the initial threshold value of the hardened layer thickness, and calculates the ratio of the two. When the ratio is small (for example, the initial threshold value of the tooth crest residual height = 2 microns, the initial threshold value of the hardened layer thickness = 12 microns, the ratio = 0.17), it indicates that the hardened layer is relatively thick, and the safety margin of burr removal is large, so the safety margin coefficient takes a larger value such as 0.8; when the ratio is large (for example, the initial threshold value of the tooth crest residual height = 4 microns, the initial threshold value of the hardened layer thickness = 8 microns, the ratio = 0.5), it indicates that the hardened layer is relatively thin, and the cutting depth needs to be controlled more carefully, so the safety margin coefficient takes a smaller value such as 0.6. The radial compensation amount is calculated by multiplying the initial threshold value of the tooth crest residual height by the safety margin coefficient, and this value is used as the basis for selecting a suitable cutting tap. The system selects a tap with a cutting depth closest to this value from the pre-set tap specification library according to the calculated radial compensation amount to perform tooth repair work. The numerical control machine tool executes feed control according to the standard cutting parameters of the selected tap to ensure the accuracy of the cutting depth. During the cutting process, the power consumption change of the spindle motor is monitored in real time by a Hall current sensor, and the sampling frequency is set to 1000 Hz to ensure that the power change details in the cutting process can be captured. The sequence of values of power change with time is recorded continuously to form a time domain power signal. This dynamic tap selection method based on the ratio relationship can determine the most suitable cutting tool according to the relative state of the hardened layer and the burr of each workpiece, avoiding the overcut or undercut problems caused by fixed specification taps.

[0019] The Hilbert transform is a mathematical method used in signal processing to extract the envelope of a signal. The envelope curve is obtained by calculating the complex modulus of the original signal and its Hilbert transform result. In the signal processing module of a numerical control system, the Hilbert transform is applied to the collected time-domain power signal point by point to obtain a smooth envelope curve that reflects the trend of power amplitude changes. The material transition feature point refers to the position where the cutting edge transitions from the extrusion hardened layer to the base material. Due to extrusion hardening, the cutting resistance of the surface layer material is significantly higher than that of the base material, resulting in a significant jump in power at the material interface. The method to identify these feature points is to perform a first-order difference operation on the envelope curve and calculate the slope change between adjacent sampling points. When the slope change amplitude exceeds a pre-set proportion of the envelope signal dynamic range, it is marked as a material transition feature point. This proportion is determined through experiments based on the hardening characteristics of the specific material. The envelope peak factor is the ratio of the envelope value at the material transition feature point to the average envelope value in the neighborhood of that point. The neighborhood range is determined based on the sampling frequency and cutting speed and is used to quantify the degree of cutting resistance mutation at the material interface. The system iterates through all the identified material transition feature points, calculates their envelope peak factors, and then takes the arithmetic mean as the first energy feature parameter. This envelope analysis-based method takes advantage of the difference in cutting resistance between the extrusion hardened layer and the base material, providing a reliable physical basis for accurately assessing the cutting state of the hardened layer.

[0020] Power spectrum analysis converts the time-domain power signal to the frequency domain through fast Fourier transform to obtain the energy distribution of the signal at different frequency components. In the signal processing software, the entire time-domain power signal is subjected to FFT transform to obtain the power spectral density function. The power spectrum slope is calculated by linear fitting of the power spectral density curve within the effective frequency band. The selection of the effective frequency band is based on the analysis of the main frequency components of the cutting process, excluding low-frequency equipment vibration and high-frequency electrical interference. Subsection correction divides the entire cutting time period into two parts: the hardened layer cutting stage and the base material cutting stage, using the time position information of the aforementioned material transition feature points. The power spectrum analysis is performed on the time-domain power signals of each stage to calculate their respective power spectrum slopes within the effective frequency band. Then, a weighted average is taken according to the time proportion of the two stages to obtain the corrected power spectrum slope as the second energy feature parameter. The generation of energy feature data is a linear combination of the first and second energy feature parameters according to pre-set weights. The weight distribution is determined based on the importance of envelope analysis in material state recognition. This subsection correction method fully considers the differences in cutting spectral characteristics between the extrusion thread hardened layer and the base material, enabling the spectral analysis results to more accurately distinguish the cutting characteristics of different material layers, providing accurate energy benchmarks for the correction of subsequent geometric detection data.

[0021] In one embodiment of the present application, the Hilbert transform is performed on the time-domain power signal to extract an envelope curve, material transition feature points reflecting changes in the cutting state of the hardened layer are identified in the envelope curve, an envelope peak factor corresponding to the material transition feature points is calculated, and a first energy characteristic parameter is obtained, including: The Hilbert transform is performed on the time-domain power signal to extract a power envelope curve, and a transition point where the power jump amplitude exceeds a preset gradient threshold is identified in the envelope curve according to the hardness difference characteristics of the extrusion hardened layer and the base material, and is marked as a material transition feature point. The ratio of the envelope peak value at each material transition feature point to the envelope mean value of the adjacent region is calculated to obtain an envelope peak factor reflecting the change in the cutting resistance of the hardened layer. Based on the angular distribution density of the material transition feature points and the numerical range of the envelope peak factor, the integrity state of the extrusion hardened layer is evaluated, and a first energy characteristic parameter is generated.

[0022] The following describes the steps involved in the above embodiment in detail: The power envelope curve is extracted by performing Hilbert transform on the time-domain power signal, which can calculate the instantaneous amplitude variation of the signal. In the signal processing module of the numerical control system, the Hilbert transform is calculated point by point for the collected time-domain power signal, the original power signal is converted into an analytic signal, and then the modulus of the analytic signal is calculated to obtain the power envelope curve. The preset gradient threshold is a power change judgment standard preset according to the hardness difference characteristics of the extrusion hardened layer and the base material. Due to the extrusion hardening, the cutting resistance of the thread surface layer material is significantly higher than that of the base material, and when the cutting edge cuts into the base material from the hardened layer, a sudden drop in power will occur. The identification of the material transition feature point is realized by calculating the slope change between adjacent data points on the envelope curve. When the power drop slope of a certain point exceeds the preset gradient threshold, the point is marked as a material transition feature point. For example, when the power drop rate of the envelope curve at a certain point reaches more than 10% per millisecond, it indicates that the cutting edge has cut into the base material from the hardened layer. This identification method based on the power gradient change can accurately capture the cutting state transition at the material interface, providing a reliable physical criterion for the indirect evaluation of the hardened layer thickness.

[0023] The envelope peak factor calculation is realized by statistically analyzing the power distribution characteristics near the material conversion characteristic points. For each identified material conversion characteristic point, the system extracts the envelope peak value at the point, and simultaneously calculates the arithmetic mean of the envelope data in a certain time window before and after the point as the envelope mean of the adjacent region. The length of the time window of the adjacent region is determined according to the cutting speed and the sampling frequency, which ensures that the power state before and after the material conversion can be fully reflected. The envelope peak factor is calculated by dividing the envelope peak value at the material conversion characteristic point by the envelope mean of the adjacent region. This ratio directly reflects the degree of change of the cutting resistance of the hardened layer relative to the matrix material. For example, when the envelope peak value at a certain material conversion characteristic point is 8 watts, and the envelope mean of the adjacent region is 6 watts, the envelope peak factor of the point is 1.33, and the larger the value, the stronger the cutting resistance of the hardened layer. This ratio calculation method eliminates the influence of the absolute power value, making the hardened layer state under different machining conditions comparable.

[0024] The integrity state evaluation of the extrusion hardened layer is realized by comprehensively analyzing the spatial distribution characteristics of the material conversion characteristic points and the numerical distribution of the envelope peak factor. The angular distribution density refers to the uniformity of the distribution of the material conversion characteristic points in the circumferential direction of the thread. The standard deviation of the distribution is obtained by counting the number of material conversion characteristic points in each angle interval. When the angular distribution density is high and uniform, it indicates that the hardened layer is well formed on the entire thread circumference. When the distribution is uneven or the density is low, it indicates that the hardened layer has local defects or insufficient thickness. The numerical range of the envelope peak factor is determined by calculating the maximum value, minimum value and average value of the envelope peak factor corresponding to all material conversion characteristic points. The stability of the numerical range reflects the consistency of the properties of the hardened layer. The system combines the angular distribution density and the numerical range of the envelope peak factor according to the preset weight, and generates the first energy feature parameter representing the integrity state of the hardened layer. This comprehensive evaluation method considers both the spatial distribution characteristics of the hardened layer and the material performance characteristics, and can fully reflect the formation quality of the extrusion thread hardened layer, providing reliable hardened layer state information for subsequent precise control strategies.

[0025] Please continue to refer to Figure 1 After the micro-cutting, the tooth crest residual height data and the hardened layer thickness data are obtained for the entire thread, and are corrected in combination with the energy feature data to generate evaluation data containing residual height peak value, thinnest hardened layer thickness and angular position information; In an embodiment of the present application, the tooth crest residual height data and the hardened layer thickness data are obtained for the entire thread, and are corrected in combination with the energy feature data to generate evaluation data containing residual height peak value, thinnest hardened layer thickness and angular position information, which includes: The thread full circle is angularly segmented, and the tooth crest residual height data and hardening layer thickness data corresponding to each angle position are obtained respectively to construct residual height distribution curve and hardening layer thickness distribution curve; According to the material conversion feature points in the energy feature data, the hardening layer cutting depth state of each angle position is identified, and the abnormal data points in the residual height distribution curve and the hardening layer thickness distribution curve are marked with confidence and corrected in value; Based on the corrected residual height distribution curve and the hardening layer thickness distribution curve, the full-circle residual height peak value and the corresponding angular position coordinates are calculated, and the full-circle thinnest hardening layer thickness and the corresponding angular position coordinates are calculated; The residual height peak value, the thinnest hardening layer thickness, the corresponding angular position coordinates and the corrected distribution curve data are structured and packaged to generate the evaluation data.

[0026] The following specifically describes the steps involved in the above embodiments: The thread full circle angular segmentation is achieved by installing the workpiece on a numerical control indexing disc, and the indexing disc is equally divided and rotated at an angle interval of 20 degrees to divide the 360-degree circle into 18 measurement positions. The tooth crest residual height data is obtained by using a contact profilometer, which is equipped with a 2mm diameter spherical probe. The probe is inserted into the thread hole along the axial direction of the thread, and the actual height of the tooth crest surface is measured at each angle position. The tooth crest residual height value is obtained by subtracting the theoretical tooth crest height at this position. The hardening layer thickness data is obtained by using a Vickers hardness tester to test the microhardness of the thread flank at each angle position. The test load is 50 grams, and the holding time is 15 seconds. According to the measured hardness value, the corresponding hardening layer thickness value is found in the pre-prepared hardness-thickness calibration table. This calibration table is prepared by testing the hardness and metallographic section thickness of 10 samples with the same material and process conditions. For every 10HV increase in hardness value, the hardening layer thickness increases by about 1 micron. The residual height distribution curve is formed by connecting the tooth crest residual height data of 18 angle positions in order with a straight line, and the hardening layer thickness distribution curve is constructed in the same way. This method based on precise indexing and contact measurement can obtain accurate geometric information of the thread full circle, avoiding the application difficulties of non-contact detection in small diameter thread holes.

[0027] The hardening layer cutting depth state recognition is realized by cross verification of the material conversion feature point density of each angle position and the geometric measurement result of the position. When the material conversion feature point density of a certain angle position is higher than the average density by more than 20%, it indicates that the hardening layer cutting of the position is sufficient; at the same time, the tooth crest residual height data of the position should be correspondingly smaller. If the material conversion feature point density is high but the tooth crest residual height data is abnormally large, the data point is marked as abnormal. The confidence marking adopts a consistency scoring method, and when the consistency of a certain data point with the expected result of the energy feature is less than 70%, the point is marked as low confidence. The numerical correction adopts a three-point weighted average method, and for the abnormal data point of low confidence, the system extracts three high-confidence data points of the previous, next and symmetric positions of the point, and performs weighted calculation according to the reciprocal of the distance. The specific calculation method is: the correction value is equal to the sum of the values of the three reference points multiplied by their corresponding weights, and the weight is the reciprocal of the angle distance between the reference point and the abnormal point divided by the sum of the three reciprocals. For example, when the position of 120 degrees is abnormal, the data of the positions of 100 degrees, 140 degrees and 300 degrees are used, and the weights are the normalized results of 1 / 20, 1 / 20 and 1 / 180 respectively. This correction method based on physical consistency ensures the rationality and accuracy of the correction result.

[0028] The full-circle extreme value calculation is realized by point-by-point numerical comparison, and the system establishes two variables to store the maximum residual height value and the minimum hardening layer thickness value found currently, and records the corresponding angle position. The algorithm starts from the position of 0 degrees, reads the corrected data of each angle position one by one, and when a larger residual height value than the current record is found, the maximum residual height value and the corresponding angle are updated; when a smaller hardening layer thickness value than the current record is found, the minimum thickness value and the corresponding angle are updated. After the traversal is completed, the residual height peak value, the minimum thickness of the hardening layer and the corresponding angle position coordinates are obtained. The system also performs a reasonableness test, and when the difference between the extreme value and the sub-extreme value exceeds 50% of the average value of the parameter, it is automatically marked as data that needs to be manually reviewed. The angle position coordinates are directly represented by angle values, and the precision is 20 degrees, which is the minimum division angle of the protractor. This exhaustive extreme value search method ensures the accuracy of the result and provides reliable position information for subsequent targeted processing.

[0029] The structured packaging of the evaluation data is implemented by using a fixed format data structure, which includes five main parts: the basic information part records the workpiece number and detection time, the extreme value information part records the numerical value and angular position coordinates of the residual height peak value, the numerical value and angular position coordinates of the thinnest thickness of the hardened layer, the distribution data part stores the corrected residual height data and hardened layer thickness data of all angular positions in the form of an 18-element array, the quality information part records the number and position of data correction points, and the metadata part records detection parameters and operation information. The data structure is organized in a key-value pair format, and each data item has a clear identifier, for example, the "residual height peak value" corresponds to a specific numerical value, and the "residual height peak value angular position" corresponds to a specific angle value. The generated evaluation data is output in JSON format, which is convenient for subsequent algorithm module parsing and processing. This structured data organization method not only ensures the integrity and readability of the data, but also meets the format requirements of automatic processing.

[0030] In an embodiment of the present application, according to the material conversion feature point in the energy feature data, the hardened layer cutting depth state of each angular position is identified, the abnormal data points in the residual height distribution curve and the hardened layer thickness distribution curve are marked with confidence and corrected in value, including: Based on the energy density difference of the material conversion feature point at each angular position, combined with the gradient decay characteristics of the extrusion hardened layer, the hardened layer cutting depth coefficient corresponding to each angular position is calculated; According to the comparison between the hardened layer cutting depth coefficient and the preset standard thickness range of the extrusion hardened layer, the angular positions exceeding the reasonable cutting range are identified, and the corresponding residual height data and hardened layer thickness data are marked as abnormal; For the data points marked as abnormal, the hardened layer cutting depth coefficient of the adjacent angular position is used for weighted interpolation correction, and the abnormal data value in the residual height distribution curve and the hardened layer thickness distribution curve is updated.

[0031] The following specifically describes the steps involved in the above embodiment: The hardening layer cutting depth coefficient calculation is based on the energy density difference of the material conversion characteristic points at each angle position and the gradient attenuation characteristics of the extrusion hardening layer. The energy density difference is obtained by calculating the average value of the envelope peak factor of the material conversion characteristic points at each angle position. For example, the average value of the envelope peak factor at 0 degree position is 1.2, and the average value of the envelope peak factor at 90 degree position is 0.8, which indicates that there is a difference in the cutting resistance of the hardening layer at different angle positions. The gradient attenuation characteristics of the extrusion hardening layer refers to the physical characteristics of the hardness gradually decreasing from the surface to the inside of the hardening layer. The surface hardness is the highest, and it decreases exponentially towards the base material. The system searches for the standard attenuation coefficient of the corresponding material according to the extrusion process parameter database, which reflects the attenuation rate of the hardness with depth. The hardening layer cutting depth coefficient is calculated by dividing the envelope peak factor at each angle position by the theoretical envelope peak factor at that position. The theoretical value is calculated based on the extrusion pressure distribution and the gradient attenuation characteristics at that angle position. For example, when the measured envelope peak factor at a certain angle position is 1.0 and the theoretical value is 1.2, the hardening layer cutting depth coefficient at that position is 0.83, which is less than 1, indicating that the cutting depth at that position exceeds the expected value. This calculation method based on the combination of energy characteristics and physical characteristics can accurately quantify the actual cutting state at each angle position, providing a reliable basis for abnormal identification.

[0032] The abnormal angle position identification is realized by comparing the hardening layer cutting depth coefficient at each angle position with the preset standard thickness range of the extrusion hardening layer. The standard thickness range of the extrusion hardening layer is determined in advance according to the material type and the extrusion process parameters. For example, the thickness range of the hardening layer of 7075 aluminum alloy T6 state under standard extrusion conditions is 8-12 microns. The system converts this thickness range into the corresponding hardening layer cutting depth coefficient range. When the hardening layer thickness is 8 microns, the upper limit of the cutting depth coefficient is 1.2, and when the thickness is 12 microns, the lower limit of the cutting depth coefficient is 0.8. For the angle positions with hardening layer cutting depth coefficients exceeding the range of 0.8-1.2, the system marks them as abnormal positions that exceed the reasonable cutting range. The abnormal marking uses a binary identification method, with normal positions marked as 0 and abnormal positions marked as 1. At the same time, the type of abnormality is recorded: cutting too deep is marked as -1, and cutting insufficiently is marked as +1. For example, when the hardening layer cutting depth coefficient at 180 degree position is 0.6, this position is marked as an abnormality of cutting too deep. This abnormality identification method based on physical constraints can accurately screen out the positions that need data correction, avoiding the subjectivity and inconsistency of manual judgment.

[0033] The abnormal data correction is achieved by weighted interpolation of the hardening layer cutting depth coefficients of the adjacent angular positions. For the data point marked as abnormal, the system first determines two normal angular positions before and after the point as reference points, totaling four reference points. The weighted interpolation adopts the distance inverse weight method, and the weight of each reference point is the inverse of the angular distance between the point and the abnormal point, and then normalization processing is performed to make the sum of all weights equal to 1. The correction calculation is performed on the residual height data and the hardening layer thickness data respectively, and the corresponding data values of the four reference points are multiplied by their weights and then added to obtain the corrected value. For example, when the 120-degree position is abnormal, the 80-degree, 100-degree, 140-degree and 160-degree positions are used as reference points, and the weights are 1 / 40, 1 / 20, 1 / 20 and 1 / 40, respectively. The normalized results are 0.125, 0.25, 0.25 and 0.125. The corrected value replaces the original abnormal data of the corresponding angular position in the residual height distribution curve and the hardening layer thickness distribution curve. The system also performs correction rationality verification, and when the difference between the corrected value and the adjacent normal data still exceeds 20%, the reference point range is expanded for re-calculation. This interpolation correction method based on the assumption of spatial continuity fully utilizes the continuity of the material properties in the circumferential direction of the thread, ensuring the physical rationality and numerical continuity of the correction results.

[0034] Please continue to refer to Figure 1 According to the evaluation data, a threshold updating algorithm is executed to output a new tooth crest residual height threshold, a hardening layer thickness threshold, and a tooth repair instruction including a radial compensation amount and an angular section compensation path. In an embodiment of the present application, the threshold updating algorithm is executed according to the evaluation data to output a new tooth crest residual height threshold, a hardening layer thickness threshold, and a tooth repair instruction including a radial compensation amount and an angular section compensation path, which includes: According to the deviation of the residual height peak value in the evaluation data from the initial tooth crest residual height threshold and the deviation of the thinnest hardening layer thickness from the initial hardening layer thickness threshold, the tooth crest residual height adjustment amount and the hardening layer thickness adjustment amount are calculated based on the double-index constraint relationship to update the new tooth crest residual height threshold and the hardening layer thickness threshold. Based on the angular position coordinates corresponding to the residual height peak value and the thinnest hardening layer thickness in the evaluation data, the angular section range that needs to be focused on is determined, the radial compensation amount of each angular section is calculated according to the new tooth crest residual height threshold and the hardening layer thickness threshold, the angular section compensation path is generated, and the tooth repair instruction is generated in combination with the updated threshold.

[0035] The following describes the steps involved in the above embodiment: The double-index threshold updating is realized by constraint optimization after calculating the residual height peak deviation and the thinnest hardening layer thickness deviation. The system reads the residual height peak data from the evaluation data, subtracts the initial threshold of the tooth top residual height to obtain the residual height deviation, and the positive value indicates that the burr is not removed enough, and the negative value indicates that the cutting is excessive. The hardening layer thickness deviation is calculated by subtracting the thinnest hardening layer thickness from the initial threshold of the hardening layer thickness, and the positive value indicates that the hardening layer is retained sufficiently, and the negative value indicates that the hardening layer is lost too much. The double-index constraint relationship is the restriction condition that the two adjustment amounts cannot change in the adverse direction at the same time. When the residual height deviation is positive and the cutting amount needs to be increased, the hardening layer thickness adjustment amount cannot be less than zero to prevent excessive cutting of the hardening layer. The tooth top residual height adjustment amount is calculated by multiplying the residual height deviation by a correction coefficient of 0.7, and the hardening layer thickness adjustment amount is calculated by multiplying the hardening layer thickness deviation by a correction coefficient of 0.8. The correction coefficient ensures the gradualness and stability of the adjustment. For example, when the residual height peak is 4 microns and the initial threshold is 3 microns, the residual height deviation is 1 micron, and the adjustment amount is 0.7 microns, and the new tooth top residual height threshold is updated to 3.7 microns. This threshold updating mechanism based on deviation feedback can dynamically adjust the control target according to the actual machining result, and realizes true adaptive control.

[0036] The angular segment range determination is realized by analyzing the spatial distribution of the angular position coordinates corresponding to the residual height peak and the thinnest hardening layer thickness. The system reads the angular position coordinates corresponding to the residual height peak and the angular position coordinates corresponding to the thinnest hardening layer thickness in the evaluation data, and sets the processing segments respectively with these two positions as the center. The 40-degree range before and after the residual height peak position is set as the burr key processing segment, and the 30-degree range before and after the thinnest hardening layer thickness position is set as the hardening layer protection key segment. When the two segments overlap, the overlapping area adopts a stricter hardening layer protection strategy. The radial compensation amount calculation adopts a segment differentiation method, and the radial compensation amount of the burr key processing segment is calculated by multiplying the new tooth top residual height threshold by a strengthening coefficient of 1.2, and the radial compensation amount of the hardening layer protection key segment is calculated by dividing the new hardening layer thickness threshold by 5 and then multiplying by a protection coefficient of 0.8. For example, when the new tooth top residual height threshold is 3.5 microns, the radial compensation amount of the burr key processing segment is 4.2 microns. The angular segment compensation path adopts segmented linear interpolation generation, and the radial compensation amount remains maximum in the key processing segment, and the compensation amount linearly decreases when the segment boundary transitions to the ordinary segment. The tooth repair instruction is generated by packaging the updated tooth top residual height threshold, hardening layer thickness threshold and angular segment compensation path into a standard data format, and the data format includes a threshold parameter field, a compensation path array field and an execution priority field. This spatially differentiated compensation strategy can realize accurate processing of different regions, and significantly improve the consistency and controllability of the tooth repair quality.

[0037] Please continue to refer to Figure 1, calling the tooth repair instruction to complete the segmented micro-cutting or burnishing processing, and again acquiring the tooth crest residual height data and the hardening layer thickness data, and confirming that the two indicators meet the updated threshold.

[0038] In an embodiment of the present application, the calling the tooth repair instruction to complete the segmented micro-cutting or burnishing processing, and again acquiring the tooth crest residual height data and the hardening layer thickness data, and confirming that the two indicators meet the updated threshold, comprises: According to the comparison of the radial compensation amount of each angular segment in the tooth repair instruction and the updated hardening layer thickness threshold, performing burnishing processing on the segment with a radial compensation amount less than the hardening layer safety margin, and performing segmented micro-cutting on the segment with a radial compensation amount greater than the hardening layer safety margin, to complete the differential processing. After the processing, the tooth crest residual height data and the hardening layer thickness data of the entire thread are re-acquired, the compliance of the processed residual height peak value with the updated tooth crest residual height threshold and the compliance of the thinnest thickness of the processed hardening layer with the updated hardening layer thickness threshold are calculated, and it is confirmed that the two indicators meet the corresponding threshold requirements at the same time.

[0039] The following specifically describes the steps involved in the above embodiment: The differential processing determines the processing method by comparing the size relationship between the radial compensation amount of each angular segment and the hardening layer safety margin. The hardening layer safety margin refers to the maximum cutting depth allowed under the premise of ensuring that the hardening layer is not completely removed, and the value is 30% of the updated hardening layer thickness threshold. The system reads the radial compensation amount data of each angular segment in the tooth repair instruction one by one, and compares the values with the hardening layer safety margin. When the radial compensation amount of a segment is less than the hardening layer safety margin, the segment adopts burnishing processing method, which means using a smooth burnishing tool to apply a certain pressure to the thread surface, and making the surface smooth by plastic deformation without removing material. When the radial compensation amount is greater than the hardening layer safety margin, the segment adopts segmented micro-cutting method, which uses a tap with a corresponding cutting depth to remove material. For example, when the radial compensation amount of an angular segment is 1.5 microns and the hardening layer safety margin is 2.0 microns, the segment performs burnishing processing; when the radial compensation amount is 3.0 microns, the segment performs segmented micro-cutting. The processing is performed by using a numerical control indexing head to control the workpiece to rotate to a specified angular position, and then selecting the corresponding tool and processing parameters according to the processing method at that position. This differential processing strategy based on safety margin judgment not only ensures the effective removal of burrs, but also maximizes the protection of the integrity of the extrusion hardened layer.

[0040] The post-processing quality verification is achieved by re-detecting the geometric parameters of the thread full circle and performing compliance evaluation with the updated threshold. The system uses the same method as the initial detection, using a contact profilometer and a Vickers hardness tester to obtain the tooth crest residual height data and hardened layer thickness data at each angle position after processing. The peak residual height after processing is obtained by finding the maximum value of the tooth crest residual height data at all angle positions, and the thinnest thickness of the hardened layer after processing is obtained by finding the minimum value of the hardened layer thickness data at all angle positions. The compliance calculation uses a percentage evaluation method, the peak residual height compliance is calculated by dividing the peak residual height after processing by the updated tooth crest residual height threshold and multiplying by 100%, when the result is less than or equal to 100%, it is determined to meet the requirements. The thinnest thickness of the hardened layer compliance is calculated by dividing the thinnest thickness of the hardened layer after processing by the updated hardened layer thickness threshold and multiplying by 100%, when the result is greater than or equal to 100%, it is determined to meet the requirements. For example, when the peak residual height after processing is 2.8 microns and the updated tooth crest residual height threshold is 3.0 microns, the compliance is 93.3%, which meets the requirement of less than or equal to 100%. The double-index confirmation requires that the peak residual height compliance after processing and the thinnest thickness of the hardened layer after processing meet their respective judgment standards at the same time, only when both indicators meet the requirements, the tooth repair process is completed. This double verification mechanism ensures the reliability of the tooth repair quality, and realizes the true balance between tooth burr removal and hardened layer protection.

[0041] With reference to Figure 2 and Figure 3 , the present application provides an extrusion thread system, which adopts the extrusion thread tooth repair self-adaptive control method of any one of the above embodiments, and therefore has the advantages of any one of the above embodiments, which will not be repeated here.

[0042] Further, the extrusion thread system comprises a cutting tap, the cutting tap comprising a connecting section 1 and a cutting section 2: The connecting section 1 is used to connect with the spindle and transmit torque; The cutting section 2 is connected with the connecting section 1, the outer peripheral wall of the cutting section 2 comprises a chip removal surface 21 and a thread surface 22, the chip removal surface 21 is concavely provided with a chip removal groove 211 extending along the length direction of the cutting section 2, and the thread surface 22 is provided with a cutting thread part 221, the depth from the tooth crest to the tooth root of the cutting thread part 221 is less than or equal to the depth from the tooth crest to the tooth root of the workpiece to be machined.

[0043] It is not difficult to understand that the connecting section 1 is the rear end part of the cutting tap, the end part thereof can adopt a standard square or hexagonal cross section design, facilitating reliable connection with the chuck of the numerical control machine tool spindle and transmitting the rotating torque of the spindle to the whole tap. The cutting section 2 is the front end working part of the cutting tap, the outer diameter thereof matches the inner diameter of the thread hole to be machined, and undertakes the actual cutting tooth repair task.

[0044] In the working process, the cutting thread part 221 plays a major role in material removal (the root position does not play a cutting role, and the root is smaller than the top size of the internal thread to be machined), and when the tap rotates into the threaded hole, the sharp edge of the cutting thread part 221 cuts the burrs and excess material on the thread top, achieving accurate trimming of the thread top. The chip groove 211 plays a key role in chip removal during cutting. The metal chips generated by cutting are guided into the chip groove 211 through spiral motion and are discharged along the longitudinal channel of the chip groove 211, preventing the accumulation of chips in the narrow threaded hole, which increases the cutting resistance or scratches the surface.

[0045] In particular, the thread top to root depth of the cutting thread part 221 is less than or equal to the design of the thread top to root depth of the workpiece to be machined, ensuring that the tap will not overcut the threaded hole. This geometric constraint provides a hardware level security for the hardening layer protection. The extrusion thread system can be configured with multiple cutting taps with different thread top to root depth sizes, forming a tap specification library, such as including taps with cutting depths of 0.05 microns, 0.1 microns, 0.15 microns, 1 micron, 1.5 microns, 2.0 microns, 2.5 microns, 3.0 microns, etc. According to the radial compensation amount calculated by the aforementioned adaptive control method, the system automatically selects the tap with the closest cutting depth from the tap specification library for the thread trimming operation, achieving the coordinated optimization of hardware configuration and software control. This multi-specification tap configuration not only improves the flexibility and accuracy of machining, but also provides personalized thread trimming solutions for threaded workpieces of different materials and different extrusion states.

[0046] Specifically, the pitch of the cutting thread part 221 is completely consistent with the standard pitch of the thread to be machined, ensuring the precise fit of the tap and the threaded hole. The width of each tooth of the cutting thread part 221 is designed to be 50-70% of the target thread top width. This ratio design not only ensures sufficient cutting ability to effectively remove the thread top burrs, but also avoids excessive cutting contact area that can damage the hardening layer.

[0047] Further, in order to enhance the performance and prolong the service life of the cutting tap, the tooth root surface of the cutting thread part 221 is deposited with a nano-composite coating, which adopts a composite structure of aluminum chromium nitride and tungsten disulfide ((Al,Cr)N+WS2), wherein the aluminum chromium nitride base layer provides excellent hardness and wear resistance, and the tungsten disulfide surface layer provides good self-lubricating performance. The coating thickness is controlled within the range of 2-5 microns, which not only ensures sufficient protection effect, but also avoids the influence of the over-thick coating on the geometric accuracy of the tool. The friction coefficient of the composite coating is controlled below 0.1, which significantly reduces the frictional resistance between the tap and the surface of the thread during cutting, reduces the generation of cutting heat, effectively prevents the performance degradation of the hardened layer due to overheating, prolongs the service life of the tap, and improves the machining quality of the thread.

[0048] The application also provides an application of the extruded thread, and it should be noted that any workpiece processed by the self-adaptive control method for thread tooth trimming of the extruded thread belongs to the application of the extruded thread.

[0049] For example, in the field of aerospace, the application is mainly aimed at the manufacturing of load-bearing components such as self-locking nuts, structural connecting rings, and key fasteners. Aviation threaded connections must meet the strict requirements of military standards such as MIL-DTL, NAS, MS, and aviation material specifications such as AS and AMS, which set extremely high thresholds for the fatigue performance, tensile strength, and environmental adaptability of threads. The cold work hardened layer and residual compressive stress generated during the extruded thread forming process are key factors for improving the fatigue performance of threads, but traditional burr removal methods often damage these beneficial microstructure features. The self-adaptive control method of the application can completely remove the burrs while maintaining the continuity and integrity of the extruded hardened layer through accurate hardened layer thickness monitoring and personalized tooth trimming parameter adjustment. This processing method preserves the continuity of the metal fiber flow lines formed during the extrusion process and maintains the cold strengthening effect of the surface material, making the threaded connection perform more excellent anti-fatigue performance under complex working conditions such as high-frequency vibration, temperature alternation, and multi-axial load. Especially when using high-performance materials such as titanium alloy and high-strength aluminum alloy, the protection of the hardened layer is crucial to ensure the long-term reliability of the thread in extreme environments.

[0050] In the field of automobile manufacturing, the application focuses on the threaded connections of key power and safety components such as engine blocks, transmission housings, suspension systems, steering mechanisms, etc. Modern automobile industry pursues lightweight design while demanding higher structural safety, which makes quality control of threaded connections crucial. The high-temperature environment in the engine compartment, corrosive media faced by chassis components, and complex load spectrum during vehicle operation all challenge the long-term stability of threaded connections. The extruded threads processed by the invented method can better resist stress concentration at the thread root by preserving the complete hardening layer structure, reducing the risk of connection failure due to micro-crack propagation. The complete preservation of the hardening layer also improves the wear resistance and corrosion resistance of the thread surface, extending the service life of threaded connections in harsh conditions. This quality advantage is particularly prominent in emerging applications such as battery pack fixation systems in electric vehicles, complex transmission mechanisms in hybrid vehicles, and precise connections in high-strength steel vehicle bodies, providing important technical support for the development of the automobile industry towards high safety and high reliability.

[0051] In the field of precision machinery manufacturing, the application widely serves key connection parts of high-precision equipment such as CNC machine tool spindle systems, industrial robot joint connections, and precision measuring instrument support structures. Precision machinery equipment has extremely strict requirements for the geometric precision and long-term stability of threaded connections, and any slight looseness or deformation will affect the machining precision or measurement accuracy of the entire machine. Machine tool spindles bear huge centrifugal force and cutting reaction force when rotating at high speed, and threaded connections must remain absolutely reliable to ensure machining quality. Industrial robots face continuous dynamic load on joint threaded connections during repeated motion, and traditional threads are prone to pre-tightening force decay and connection loosening. The invented method protects the extruded hardening layer, improves the hardness and wear resistance of the thread surface, reduces plastic deformation and wear under long-term cyclic load, and ensures the long-term stability of threaded connections. In addition, in the fields of marine engineering equipment, rail transit vehicles, and heavy engineering machinery, these devices face seawater corrosion, vibration impact, heavy load operation, etc. The complete hardening layer structure provides stronger fatigue resistance and corrosion resistance for threaded connections, significantly extending the maintenance cycle and service life of the equipment.

[0052] The above specific embodiments further illustrate the purpose, technical solutions, and benefits of the present application. It should be understood that the above description is only for specific embodiments of the present application and does not limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An adaptive control method for extruded thread trimming, characterized in that, include: Obtain material information and historical extrusion pressure data of the workpiece to be processed, collect the spindle no-load power waveform and extract energy baseline parameters, and determine the initial threshold of tooth crest residual height and the initial threshold of hardened layer thickness. The radial compensation amount is set according to the initial threshold and a micro-cut is performed. At the same time, the power waveform of the cutting process is analyzed to obtain energy characteristic data. After the micro-cutting, the residual height data of the tooth crest and the thickness data of the hardened layer are obtained for the entire circumference of the thread, and the energy characteristic data are combined for correction to generate evaluation data containing the peak residual height, the thinnest thickness of the hardened layer and angular position information. Based on the evaluation data, a threshold update algorithm is executed to output new tooth top residual height threshold, hardened layer thickness threshold, and tooth repair instructions including radial compensation amount and angular segment compensation path; The tooth repair command is invoked to complete segmented micro-cutting or calendering, and the residual tooth height and hardened layer thickness data are obtained again to confirm that the two indicators meet the updated threshold.

2. The adaptive control method for extruded thread trimming according to claim 1, characterized in that, The process involves setting a radial compensation amount according to an initial threshold and performing micro-cutting, while simultaneously analyzing the power waveform during the cutting process to obtain energy characteristic data, including: Based on the numerical relationship between the initial threshold of the residual tooth height and the initial threshold of the hardened layer thickness, the safety margin coefficient of the radial compensation amount is calculated. Based on the safety margin coefficient, the radial compensation amount is determined and micro-cutting is performed. The spindle power waveform during the cutting process is acquired simultaneously to obtain the time-domain power signal. The time-domain power signal is subjected to Hilbert transform to extract the envelope curve, the material transformation feature points in the envelope curve that reflect the changes in the cutting state of the hardened layer are identified, the envelope peak factor corresponding to the material transformation feature points is calculated, and the first energy feature parameter is obtained. Power spectrum analysis is performed on the time-domain power signal to calculate the power spectrum slope. The power spectrum slope is then segmented and corrected based on the material conversion feature points to obtain a second energy feature parameter. The first energy feature parameter and the second energy feature parameter are then combined to generate energy feature data.

3. The adaptive control method for extruded thread trimming according to claim 2, characterized in that, The process involves performing a Hilbert transform on the time-domain power signal to extract the envelope curve, identifying material transition feature points in the envelope curve that reflect changes in the cutting state of the hardened layer, calculating the envelope peak factor corresponding to the material transition feature points, and obtaining the first energy feature parameter, including: The time-domain power signal is subjected to Hilbert transform to extract the power envelope curve. Based on the hardness difference between the extruded hardened layer and the matrix material, the transition points in the envelope curve where the power jump amplitude exceeds the preset gradient threshold are identified and marked as material transition feature points. The ratio of the envelope peak value at each material transformation characteristic point to the mean envelope value of the adjacent region is calculated to obtain the envelope peak factor that reflects the change in the cutting resistance of the hardened layer. Based on the angular distribution density of the material conversion feature points and the numerical range of the envelope peak factor, the integrity state of the extrusion hardened layer is evaluated, and a first energy feature parameter is generated.

4. The adaptive control method for extruded thread trimming according to claim 1, characterized in that, The residual height data and hardened layer thickness data of the entire thread circumference are acquired separately, and corrected in combination with the energy characteristic data to generate evaluation data containing peak residual height, minimum hardened layer thickness, and angular position information, including: The thread is segmented by angle, and the residual height of the tooth crest and the thickness of the hardened layer are obtained at each angle position. The residual height distribution curve and the hardened layer thickness distribution curve are then constructed. Based on the material conversion feature points in the energy feature data, the cutting depth state of the hardened layer at each angle position is identified, and the abnormal data points in the residual height distribution curve and the hardened layer thickness distribution curve are marked with confidence and numerically corrected. Based on the corrected residual height distribution curve and hardened layer thickness distribution curve, the peak value of the residual height around the whole circumference and its corresponding angular position coordinates are calculated, and the thinnest thickness of the hardened layer around the whole circumference and its corresponding angular position coordinates are calculated. The evaluation data is generated by structurally encapsulating the residual peak value, the thinnest thickness of the hardened layer, the corresponding angular position coordinates, and the corrected distribution curve data.

5. The adaptive control method for extruded thread trimming according to claim 4, characterized in that, The step of identifying the hardened layer cutting depth state at each angular position based on the material conversion feature points in the energy characteristic data, and performing confidence marking and numerical correction on abnormal data points in the residual height distribution curve and hardened layer thickness distribution curve, includes: Based on the energy density difference of the material conversion feature points at each angular position, and combined with the gradient attenuation characteristics of the extrusion hardening layer, the cutting depth coefficient of the hardening layer at each angular position is calculated. Based on the comparison between the cutting depth coefficient of the hardened layer and the preset standard thickness range of the extruded hardened layer, the angle position that exceeds the reasonable cutting range is identified, and the corresponding residual height data and hardened layer thickness data are marked as abnormal. For data points marked as abnormal, weighted interpolation correction is performed based on the hardened layer cutting depth coefficient at adjacent angular positions to update the abnormal data values ​​in the residual height distribution curve and the hardened layer thickness distribution curve.

6. The adaptive control method for extruded thread trimming according to claim 1, characterized in that, The threshold update algorithm is executed based on the evaluation data, outputting new threshold values ​​for residual tooth height, hardened layer thickness, and restoration instructions including radial compensation and angular segmental compensation paths, including: Based on the deviation between the peak residual height and the initial threshold of residual height at the top of the tooth and the deviation between the thinnest thickness of the hardened layer and the initial threshold of the thickness of the hardened layer in the evaluation data, the adjustment amount of residual height at the top of the tooth and the adjustment amount of the thickness of the hardened layer are calculated based on the dual-index constraint relationship, and new thresholds for residual height at the top of the tooth and thickness of the hardened layer are updated. Based on the angular position coordinates corresponding to the peak residual height and the thinnest thickness of the hardened layer in the evaluation data, the range of angular segments that need to be focused on are determined. The radial compensation amount of each angular segment is calculated according to the new residual height threshold and hardened layer thickness threshold. An angular segment compensation path is generated and combined with the updated threshold to generate a tooth repair instruction.

7. The adaptive control method for extruded thread trimming according to claim 1, characterized in that, The process involves invoking the dental repair command to complete segmented micro-cutting or polishing, and then re-acquiring data on the residual tooth height and hardened layer thickness to confirm that both indicators meet the updated thresholds, including: Based on the comparison between the radial compensation amount of each angular segment in the dental repair instruction and the updated hardened layer thickness threshold, the segments with radial compensation amount less than the hardened layer safety margin are subjected to troweling, and the segments with radial compensation amount greater than the hardened layer safety margin are subjected to segmented micro-cutting to complete the differentiated processing. After machining, the residual height data of the tooth crest and the thickness data of the hardened layer are re-acquired for the entire circumference of the thread. The conformity of the peak residual height after processing with the updated residual height threshold and the conformity of the thinnest thickness of the hardened layer after processing with the updated hardened layer thickness threshold are calculated to confirm that both indicators meet the corresponding threshold requirements.

8. A threaded extrusion system, characterized in that, The extrusion thread system employs the extrusion thread trimming adaptive control method as described in claims 1 to 7.

9. The extrusion thread system as described in claim 8, characterized in that, The extrusion thread system includes a cutting tap, the cutting tap comprising: Connecting section, used to connect to the main shaft and transmit torque; The cutting section is connected to the connecting section. The outer peripheral wall of the cutting section includes a chip removal surface and a threaded surface. The chip removal surface is recessed with a chip removal groove extending along the length direction of the cutting section. The threaded surface is provided with a cutting thread portion. The depth from the crest to the root of the cutting thread portion is less than or equal to the depth from the crest to the root of the workpiece to be processed.

10. An application of extruded threads, characterized in that, The adaptive control method for extrusion thread trimming as described in any one of claims 1 to 7 is adopted.

Images