Monitoring and feedback methods during thread forming, extrusion thread systems and their applications

Abstract

This invention discloses a monitoring and feedback method, a thread extrusion system, and its application in the thread forming process. The method includes synchronously acquiring process signals during thread forming and generating reference information based on pitch phase mapping. It also involves real-time comparison to identify phase intervals deviating from a threshold, combining processing stage information to implement tentative disturbances and collect response data when these disturbances occur subsequently, confirming the anomaly type, and executing directional process intervention synchronized with the phase. Finally, it determines the processing quality and outputs control conditions based on the phase data after intervention. This invention enables precise state detection and closed-loop control of the thread processing process under conditions without visible light, ensuring stable thread quality and improving processing efficiency and equipment adaptability.

Description

Technical Field

[0001] This invention relates to the field of manufacturing process monitoring and closed-loop control technology, and in particular to a monitoring and feedback method, a thread extrusion system and its application in the thread forming process. Background Technology

[0002] The manufacturing industry is evolving towards a "dark factory" model, where production environments rely entirely on automated equipment, sensing systems, and control systems for processing and quality assurance, eliminating the need for manual observation under visible light. Since no one directly operates in a dark factory, there's no need for human illumination, saving energy and avoiding the interference of heat from light sources on the processing environment temperature. This also reduces maintenance workload and safety hazards associated with lighting equipment. In lit environments, the process status of thread machining is often monitored manually or with visible light cameras, such as observing chip flow, thread surface quality, and tool wear. Some systems also incorporate force sensing and acoustic emission signals for auxiliary judgment. However, in a dark environment, visible light vision becomes ineffective. During continuous machining, rapid process transitions and complex signal changes mean that failure to accurately identify the status and adjust machining parameters in real time can easily lead to fluctuations in thread accuracy or tool damage. Therefore, with the industry's shift towards "dark factories," effectively monitoring the status of tap machining in a light-free environment and implementing real-time feedback control based on the monitoring results to ensure stable thread quality has become a pressing technical challenge in this field. Summary of the Invention

[0003] This application provides a monitoring and feedback method for the thread forming process, aiming to: effectively detect the status of the thread forming process in a no-visible-light environment, and implement real-time feedback control based on the detection results, in the context of industry transformation towards fully dark factories, to ensure stable thread quality.

[0004] To achieve the above objectives, embodiments of this application provide a monitoring and feedback method for the thread forming process, including: During the thread forming process, a sampling method synchronized with the tap rotation and feed is used to acquire process signals, and the process signals are mapped according to the pitch phase to obtain a mapped phase dataset and real-time phase data for online comparison. The mapping phase dataset is used to form reference information for determining the processing status, and the real-time phase data is compared with the reference information during the processing to identify the phase intervals that deviate from the threshold. Record the timing of the occurrence of the phase interval that deviates from the threshold in subsequent processing, and apply a tentative perturbation at the timing of the occurrence, and collect the process response data after the perturbation; Based on the correspondence between the process response data and the baseline information, an abnormal phase interval is identified, and when the abnormal phase interval subsequently appears, a process intervention synchronized with the phase is performed. Based on the phase data after process intervention, output the conditions for judging processing quality or process control.

[0005] This application also proposes an extrusion thread system, which employs the monitoring and feedback method in the thread forming process described above.

[0006] The present invention also provides an application of extruded threads, wherein the application of extruded threads adopts the monitoring and feedback method in the thread forming process of the above embodiments.

[0007] The technical solution provided in this application acquires process signals during thread forming by sampling in sync with tap rotation and feed. These signals are then mapped according to pitch phase to form a mapped phase dataset reflecting the processing state corresponding to each phase. Simultaneously, real-time phase data corresponding to the current cycle is extracted. The mapped phase dataset spatially and periodically organizes the signal characteristics of each tooth position and each phase during processing, establishing a stable correspondence between the processing signals and the tap tooth sequence and pitch position. Based on this, reference information for judging the processing state is extracted from the mapped phase dataset. This reference information includes reference standards for signal amplitude, waveform shape, etc., at different phases. During processing, the real-time phase data is compared and aligned with the reference information to accurately locate the specific phase position at the moment signal fluctuations occur, identify phase intervals deviating from a set threshold, and mark these abnormal phase intervals.

[0008] In subsequent machining cycles, when the marked phase interval reappears, the system applies a tentative disturbance at that phase location. For example, it might apply a small feed or medium pressure pulsation during the extrusion stage, or a spindle speed or feed rate pulsation during the cutting stage. The process response triggered by the disturbance is collected in real time and analyzed against baseline information to confirm whether the anomaly in that phase interval is stable and its specific nature. Subsequently, in subsequent occurrences of the anomalous phase interval, a phase-synchronized directional process intervention is executed, precisely applying control adjustments to the corresponding machining stage and position. The entire process utilizes the periodic characteristics of pitch phase mapping to lock the detection, verification, and intervention stages at the specific timing and spatial location of the anomaly. This allows for precise perception of changes in the machining state and immediate response, even in complete darkness and without visible light monitoring, through multi-cycle signal comparison and disturbance verification, thereby maintaining stable thread quality. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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 the structures shown in these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of an embodiment of the monitoring and feedback method in the thread forming process according to the present invention; Figure 2 This is a schematic diagram of the structure of a tap body of an embodiment of the extrusion thread system of the present invention; Figure 3 for Figure 2 A magnified view of a portion of the tap body.

[0011] Explanation of icon numbers: 1. Connecting section; 2. Cutting section; 21. Chip removal surface; 22. Threaded surface; 23. Chip removal groove; 24. Cutting threaded section; 3. Extrusion section; 31. Extruded threaded section.

[0012] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

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

[0014] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0015] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the term "and / or" throughout the text includes three solutions; taking A and / or B as an example, it includes technical solution A, technical solution B, and a technical solution that simultaneously satisfies A and B. Furthermore, the technical solutions of various embodiments can be combined with each other, provided that they are feasible for those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0016] Specifically, the forming of threaded holes can be accomplished either using a single compound tap or by sequentially machining with multiple separate taps. The compound tap performs extrusion forming in the initial stage, using the tap's outer thread to plastically compress the hole wall material, thus forming the basic shape of the internal thread without producing chips. In the subsequent stage, it performs cutting, removing burrs or minor protrusions formed during the extrusion process, further improving the thread's dimensional accuracy and surface quality. In the process using multiple separate taps, the first extrusion tap is responsible for the plastic forming of the thread, while the second cutting tap focuses on finishing cutting; the two work together to complete a similar machining process as the compound tap. Regardless of the method, the machining process includes two stages: extrusion forming and cutting forming. The state of these two stages directly determines the accuracy and consistency of the thread forming.

[0017] The manufacturing industry is evolving towards a "dark factory" model, where production environments rely entirely on automated equipment, sensing systems, and control systems for processing and quality assurance, eliminating the need for manual observation under visible light. Since no one directly operates in a dark factory, there's no need for human illumination, saving energy and avoiding the interference of heat from light sources on the processing environment temperature. This also reduces maintenance workload and safety hazards associated with lighting equipment. In lit environments, the process status of thread machining is often monitored manually or with visible light cameras, such as observing chip flow, thread surface quality, and tool wear. Some systems also incorporate force sensing and acoustic emission signals for auxiliary judgment. However, in a dark environment, visible light vision becomes ineffective. During continuous machining, rapid process transitions and complex signal changes mean that failure to accurately identify the status and adjust machining parameters in real time can easily lead to fluctuations in thread accuracy or tool damage. Therefore, with the industry's shift towards "dark factories," effectively monitoring the status of tap machining in a light-free environment and implementing real-time feedback control based on the monitoring results to ensure stable thread quality has become a pressing technical challenge in this field.

[0018] Therefore, one embodiment of this application provides a monitoring and feedback method for the thread forming process to solve the problems existing in the background described above. Figure 1 This is a flowchart illustrating a monitoring and feedback method during the thread forming process according to an embodiment of this application. In this embodiment, the method includes: Please see Figure 1 During the thread forming process, a sampling method synchronized with the tap rotation and feed is used to acquire process signals, and the process signals are mapped according to the pitch phase to obtain a mapped phase dataset and real-time phase data for online comparison. Specifically, in thread forming, the forming process includes two stages: First, the extrusion forming stage, where the extrusion tap, through rotation and axial feed, contacts the workpiece hole wall, causing the hole wall material to plastically flow and form along the thread profile direction, creating an internal thread with a basic geometric shape. Second, the cutting forming stage, where the cutting tap removes burrs, micro-protrusions, or excess material remaining from the extrusion stage, ensuring the thread profile, dimensions, and surface roughness meet requirements. These two stages can be performed using the same composite tap (such as...). Figure 2 The process can be completed continuously on the product shown, or it can be completed in steps using multiple separate taps, for example, the first tap is a forming tap and the second tap is a cutting tap.

[0019] In this scheme, the process signal acquisition method using sampling synchronized with tap rotation and feed means that the acquisition timing of the process signal maintains a strict correspondence with the tap spindle angular position and axial feed position. This can be achieved by configuring a high-resolution rotary encoder on the machine tool spindle to acquire the spindle angle signal in real time. Combined with the feed axis position feedback signal from the CNC system, the sampling trigger point is set to occur when the spindle rotates to a specific angle and the feed position meets the pitch correspondence. This ensures that each acquired data corresponds one-to-one with the tap tooth sequence and pitch phase, guaranteeing phase alignment between different cycles. Alternatively, software interpolation can be used. The interpolation module inside the machine tool controller calculates the sampling trigger time in real time based on the current spindle speed and feed rate, achieving synchronous sampling and maintaining consistent sampling positions even when the spindle or feed rate is finely adjusted.

[0020] The process signals may include, but are not limited to, spindle current signals, feed force or torque signals, acoustic emission signals, vibration acceleration signals, and cooling medium pressure signals. Different signals can be acquired in real time by corresponding sensors. These sensors can be installed in locations such as the machine tool spindle box, tool holder, workpiece fixture, and cooling system piping to adapt to different detection requirements. For different machine tools and control systems, in addition to hardware encoders and sensor triggering methods, synchronous sampling can also be achieved through a high-frequency data acquisition card and the CNC system communication interface. Equivalent implementation schemes also include coordinating the sampling timing of the spindle and sensors on robots or dedicated machining equipment through a synchronous clock bus (such as EtherCAT, Profinet IRT, etc.), or combining a high-speed camera with a grating encoder to acquire signals in the non-visible light band (such as infrared).

[0021] By using the above methods, we can ensure that the data from each sampling not only reflects the physical state at the moment of processing, but also achieves comparability and periodicity between different cycles and different tooth positions, providing an accurate spatiotemporal reference for subsequent pitch phase mapping, benchmark comparison, and anomaly positioning.

[0022] In one embodiment of the present invention, the process signal is mapped according to pitch phase to obtain a mapped phase dataset and real-time phase data for online comparison, including: The process signals are divided into subsets related to material plastic flow and subsets related to chip generation based on signal characteristics. Pitch phase segmentation mapping is performed in combination with tap tooth sequence to obtain dual-channel phase mapping results corresponding to extrusion forming and cutting forming. A process transition window is set with the extrusion forming end phase and the cutting forming start phase as the boundary, and phase alignment and continuity constraints are performed on the dual-channel phase mapping results within the process transition window, wherein the first circle phase of the second infeed is taken as the cutting forming start phase; After phase alignment is completed, process mode labels and material response tags are attached to each phase position, and the labels are bound and stored with the process signals of the corresponding phase positions to generate a mapped phase dataset with associated object attributes. While generating the mapped phase dataset, the phase data corresponding to the current processing cycle is extracted as real-time phase data.

[0023] The following is a detailed description of the steps involved in the above embodiments: First, based on the synchronously acquired spindle angular position and axial feed position, each pitch cycle is unfolded into a 0–360° phase coordinate system, and an index is established for each tooth region along the phase axis according to the tap tooth sequence. Then, mechanism-oriented feature extraction is performed on the multi-source process signals: low-frequency and quasi-static components reflecting material plastic flow (such as slow changes in feed thrust, step-like increases in spindle current, and gradual increases in medium pressure) are extracted as subsets related to material plastic flow; high-frequency and impact characteristics reflecting chip generation (such as acoustic emission count rate, vibration envelope pulses, and serrated texture of force signals) are extracted as subsets related to chip generation. Based on the phase coordinates and tooth sequence, the two subsets are mapped to the same pitch phase axis, forming a dual-channel phase mapping result corresponding to extrusion forming and cutting forming. The significance of this is to decouple the mixed mechanism responses on the same time axis under the phase-tooth sequence coordinate system, facilitating subsequent comparison and intervention at precise phase positions. Equivalent implementation methods can be achieved by splitting the frequency bands using front-end hardware (high-frequency channel for collecting acoustic emission and vibration, and low-frequency channel for collecting force and current), or by using time-frequency analysis to divide the data based on energy concentration and impact rate, ensuring that the two subsets correspond one-to-one in the phase index.

[0024] The process transition window setting, phase alignment, and continuity constraints can be implemented as follows: The extrusion forming end phase and the cutting forming start phase serve as boundaries, defining a finite-width process transition window on the phase axis. The cutting forming start phase is defined by the phase of the first circle of the second feed, i.e., the full circle of the first stable cutting after the extrusion stage's influence has attenuated. The boundary position can be calculated based on tool geometry and feed parameters, or it can be located during trial cutting through characteristic inflection point detection (a significant rise in the high-frequency channel and periodic sawtooth patterns in the low-frequency channel indicate the start of cutting). Within this window, phase alignment is performed on the dual-channel phase curves of adjacent cycles to ensure consistent phase zeros in the transition zone. Pseudo-steps and misalignments at the switching instant are eliminated through interpolation and resampling, ensuring a continuous transition between the two channels at the boundary. Through this process, phase drift and amplitude abrupt changes caused by stage switching are normalized to the same reference frame, allowing direct comparison of the position and morphology of the same mechanism in different cycles. An equivalent implementation can set the window width to a fixed degree related to the tool-material combination, or use an adaptive window to automatically adjust the width according to the boundary uncertainty and online stability index; in addition to cross-correlation, the phase alignment algorithm can also be implemented using the anchor point peak-valley alignment method.

[0025] After phase alignment is completed, a record entry is generated for each phase position, containing four basic indices: pitch number, phase angle, tap tooth sequence, and channel identifier. Additional process mode labels (extrusion forming, within the process transition window, cutting forming) and material response markers (such as sufficient plasticity, enhanced springback, increased friction, continuous chips, segmented chips, and chip removal obstruction) are added. The multi-source process signals at the corresponding time are bound to this entry in the form of raw values ​​and extracted features, and written into the mapped phase dataset. To ensure retrieval and traceability, the timestamp and cumulative tool machining length are simultaneously recorded in the entry. This organization method gives each phase point a triple identity: location, mechanism, and signal. Subsequent comparisons and interventions can be precisely located on the corresponding teeth and phases according to the index. An equivalent implementation can refine the material response markers into numerical levels for statistical purposes, or add cooling medium status labels (pressure range, nozzle opening) to interpret chip removal-related phase characteristics, thereby improving diagnostic resolution without changing the core framework of phase-tooth sequence-channel.

[0026] The extraction and output of real-time phase data are completed synchronously with the generation of the aforementioned dataset. Using the current pitch cycle as the unit, a read-only view for that cycle is established. Each sampling point within the 0–360° range, along with its channel identifier, process mode label, and material response marker, is grouped and output to form real-time phase data, which serves as the direct input for online comparison and feedback control. To meet timeliness requirements, the data channel is set to have a maximum lag of no more than one sampling cycle. To improve alignment speed, resampling can be performed at a fixed phase resolution at the output end, or, in bandwidth-constrained situations, only feature vectors isomorphic to the mapped phase dataset can be output, while retaining the phase and tooth sequence indexes to support rapid backtracking. Through this synchronous output, online discrimination is always based on data from the latest cycle that is consistent with the historical mapping structure, thus achieving cross-cycle comparability while avoiding error accumulation caused by cross-cycle phase drift. An equivalent implementation can use a ring buffer scrolling window to manage the real-time view, or use deterministic industrial Ethernet between the CNC system and the host computer to ensure consistency between phase triggering and data transmission, ensuring real-time performance and reproducibility.

[0027] Please continue reading. Figure 1 The reference information for determining the processing status is formed based on the mapped phase dataset, and the real-time phase data is compared with the reference information during the processing to identify the phase intervals that deviate from the threshold. In one embodiment of the present invention, the step of forming reference information for determining the processing state based on the mapped phase dataset, and comparing the real-time phase data with the reference information during processing to identify phase intervals deviating from a threshold, includes: Based on the phase data corresponding to the extrusion forming stage and the cutting forming stage in the mapped phase dataset, a dual-channel reference information set is constructed, and an independent set of discrimination parameters is established in the process transition zone from the end of extrusion to the start of cutting. During the processing, the real-time phase data is aligned with the reference information of the corresponding stage according to the phase position, and the amplitude, phase difference and waveform shape are compared in the normal phase area and the process transition area respectively to determine whether it deviates from the threshold. The phase interval of real-time phase data that is determined to deviate from the threshold is located, and the phase interval deviating from the threshold and the processing mode information corresponding to the phase interval deviating from the threshold are output.

[0028] The following is a detailed description of the steps involved in the above embodiments: Several pitch cycles in a qualified state are strictly aligned with the tap tooth sequence according to their phase positions. The phase position can be obtained by synchronously sampling the angle signal output by the spindle encoder and the feed position, and uniformly mapped to the 0–360° coordinate range; the tap tooth sequence index can be established based on the number of tool teeth and the reference position of the first tooth, so that each phase sampling point has a unique tooth position identifier. Based on the alignment, reference curves of phase-amplitude are calculated on the extrusion forming channel and the cutting forming channel respectively, and a tolerance band is generated for each phase position. The tolerance band can be composed of the mean ± quantile interval of multiple cycles, or it can be represented by the median ± robust scale (such as median absolute deviation). Its phase resolution should be matched with the sampling frequency and signal characteristic width to ensure that the tolerance band can reflect the stable state and will not be misled by instantaneous fluctuations. Each phase point also records the first-order phase slope and local energy (which can be the square integral of the signal within a certain number of degrees near the phase point or the frequency domain energy) to characterize the dynamic change characteristics of the point. The extrusion forming channel emphasizes the smooth envelope and slope continuity of low-frequency and quasi-static components, while the cutting forming channel emphasizes the repeatability of periodic impacts and high-frequency energy. A separate set of discrimination parameters is established for the process transition zone from the end of extrusion to the start of cutting. These parameters include phase continuity constraints, changes in the ratio of high- and low-frequency energy between channels, the rate of change of the envelope slope, and the phase position of the characteristic peak (or high-frequency energy peak) as it transitions from the extrusion channel to the cutting channel, used to characterize the normal trajectory of stage switching. The threshold values ​​for these parameters can be set based on sensor noise levels, machine tool control resolution, and the statistical dispersion of qualified samples. An adaptive fine-tuning range can be set during online operation to compensate for baseline drift caused by gradual tool dulling or batch variations in material. In scenarios with high stability, such as aluminum alloy internal hole forming, 10–20 qualified samples are typically sufficient to generate a stable dual-channel reference information set. In scenarios with greater volatility, the number of sample cycles can be increased or the phase resolution reduced to improve statistical stability. An equivalent implementation can represent the tolerance band as a percentile envelope or confidence interval, or replace the energy index with statistical characteristics such as pulse count density, while still achieving the same benchmark constraint effect.

[0029] Next, in the online judgment phase, the real-time phase data is aligned with the corresponding stage's reference information according to phase position. The comparison process is performed separately in the regular phase zone and the process transition zone. In the regular phase zone, the amplitude deviation, phase difference, and waveform morphology similarity of the real-time phase data to the reference curve are calculated: the amplitude deviation can be directly taken as the difference or relative deviation between the real-time value and the reference value; the phase difference can be characterized by the difference in the position of characteristic peaks or the difference in the position of cross-correlation peaks to indicate the meshing timing offset; the waveform morphology similarity can be characterized by the normalized correlation coefficient, the inverse ratio of the mean square error, or the envelope shape consistency measure to indicate whether the local morphology remains stable. The three can be comprehensively judged according to a weighted strategy, and only when the comprehensive deviation exceeds the tolerance band of the corresponding phase is it judged as a deviation threshold. In the process transition zone, an independent set of discrimination parameters is used to perform composite comparison, focusing on checking whether the transfer of the high and low frequency energy ratio between channels is completed within the preset phase window, whether the envelope slope is continuous, and whether the phase positions of the transition start and end fall within the allowable range. The allowable range can be calculated based on the tool geometry and feed parameters, or determined through the statistical boundaries of qualified samples. The significance of this differentiation strategy lies in the following: in the conventional phase region, the sensitivity is improved by utilizing highly repeatable steady-state indicators; in the process transition region, the false alarms caused by fluctuations in normal operating conditions are suppressed by utilizing continuity and energy transfer characteristics, thereby maintaining stable judgment during continuous processing or parameter fine-tuning. An equivalent implementation can replace waveform morphology similarity with interval consistency criteria based on key shape features such as peak-valley spacing and pulse density, while maintaining the same composite comparison logic.

[0030] For real-time phase data deemed to deviate from the threshold, phase interval positioning and processing mode information output are performed. Phase interval positioning can be achieved by using a sliding window method to detect sampling points on the phase axis point by point. Sampling points that continuously exceed the tolerance zone are merged into candidate phase segments, and adjacent segments with an interval smaller than the set minimum phase gap are fused to obtain an abnormal interval with a clear start and end phase angle. The length of the sliding window can be determined based on the phase resolution and the minimum duration of the target anomaly. Subsequently, based on the channel where the phase interval is located and its relationship with the process transition zone, the corresponding processing mode information is output, i.e., extrusion forming, process transition zone, or cutting forming, along with the located tap tooth sequence and pitch number, forming a structured result for subsequent intervention or recording. To suppress occasional noise, two stability constraints, minimum phase width and minimum repetition count, can be set, or a confidence score method can be used, confirming the positioning result only when the score exceeds the set threshold. In scenarios where anomalies have a significant impact, such as blind hole machining of steel parts, this positioning result can pinpoint the problem to a specific tooth position and phase segment, allowing exploratory disturbances or process interventions to be implemented within the same phase coordinate system. An equivalent implementation can perform equal-interval resampling of the phase axis or extract segmented feature vectors when bandwidth is limited, and then output the results according to the same interval fusion rules, thereby maintaining the consistency between the positioning and pattern output.

[0031] Please continue reading. Figure 1 Record the timing of the occurrence of the phase interval that deviates from the threshold in subsequent processing, and apply a trial perturbation at the timing of the occurrence, and collect the process response data after the perturbation; In one embodiment of the present invention, the step of recording the occurrence timing of the phase interval deviating from the threshold in subsequent processing, applying a tentative perturbation at the occurrence timing, and collecting process response data after the perturbation includes: Based on the correspondence between the tap rotation period and the axial feed, the start and end phase positions of the phase interval that deviates from the threshold are registered, and the corresponding subsequent occurrence timing is generated. Based on the processing stage information corresponding to the phase interval that deviates from the threshold, a trial disturbance synchronized with the phase is performed within the subsequent occurrence time: when the phase interval that deviates from the threshold is in the extrusion forming stage, a micro-pulse is applied to the feed or medium pressure to elicit a material plastic or springback response; when the phase interval that deviates from the threshold is in the cutting forming stage, a micro-pulse is applied to the spindle speed or feed rate to elicit a chip generation or chip removal response. During the exploratory disturbance, disturbance response process signals are acquired within the time window corresponding to the phase interval that deviates from the threshold, and corresponding process response data are formed according to pitch phase mapping. Amplitude change features, phase delay features, or attenuation features in the process response data are extracted, and the amplitude change features, phase delay features, or attenuation features are bound and stored with the phase interval that deviates from the threshold and its corresponding processing stage information for subsequent anomaly confirmation and directional process intervention.

[0032] The following is a detailed description of the steps involved in the above embodiments: To achieve registration and subsequent occurrence timing, based on the correspondence between the tap rotation cycle and axial feed, after detecting a phase interval deviating from the threshold, the start and end phase positions (phase start and phase end) and the corresponding tap tooth sequence and pitch number are recorded. The spindle angle and feed displacement are given by the encoder and servo feedback. Within the same hole, the phase interval repeats in a fixed sequence in each pitch cycle. Therefore, the time window for the next cycle to reach the same phase interval is calculated based on the phase interval of the current cycle, and subsequent occurrence timing is generated. In the case of an integrated tap, the subsequent occurrence timing is the next cycle of the same tool pass. In the case of a split tap, the subsequent first occurrence timing of the cutting tap is aligned with the phase of the first cycle of the second tool pass. To ensure execution accuracy, a phase pre-trigger amount and phase jitter tolerance are set before the subsequent occurrence timing to schedule disturbance commands in advance and eliminate phase errors caused by small speed fine adjustments. When the number of remaining cycles at the end of the blind hole is insufficient, the subsequent occurrence timing of the phase interval is postponed to the next machining cycle and all index information is retained. This approach allows for precise binding of anomaly location results to execution times on the timeline, ensuring subsequent actions land within the target phase window. An equivalent implementation can utilize phase-locked interrupts within the controller or a host computer event queue for scheduling; as long as the synchronization constraint with the pitch phase is met, the same timing consistency can be achieved.

[0033] For exploratory disturbances synchronized with the phase, different micro-excitations are implemented based on the machining stage information corresponding to the phase interval deviating from the threshold. In the extrusion forming stage, small-amplitude, controlled-duration pulsations are applied to the feed or medium pressure at subsequent occurrences to elicit material plastic or springback responses. The feed pulsation amplitude can be 1%–3% of the current feed rate, and the pulsation duration covers 50%–100% of the phase interval, with smooth acceleration and deceleration to avoid mechanical shock. The medium pressure pulsation amplitude can be 5%–10% of the rated pressure, and the pulsations are symmetrically arranged along the center of the phase interval. In the cutting forming stage, micro-pulsations of the same magnitude are applied to the spindle speed or feed rate at subsequent occurrences to elicit chip generation or chip removal responses. The rise and fall of the speed pulsation transitions linearly or in an S-shape within the phase window, ensuring that the disturbance is only used for diagnostic purposes and does not change the tooth profile dimensions. The disturbance amplitude is limited to a small proportion because a identifiable response difference needs to be obtained without compromising the established process quality. Phase-locked execution ensures that the spatial location of the excitation and the abnormal mechanism is consistent, thereby improving the reliability of causal interpretation. An equivalent implementation can replace feed pulsations with axial micro-displacement pulsations, or rotational speed pulsations with torque-given micro-pulsations; alternatively, small-amplitude pulsations of cooling medium pressure or flow direction can be used during the cutting stage to selectively excite the chip removal state.

[0034] During the initial disturbance, disturbance response signals are continuously acquired within the time window corresponding to the phase interval deviating from the threshold, and corresponding process response data are generated by pitch-phase mapping. To ensure consistency in comparison, sampling is aligned along the phase axis to the same phase resolution as the reference information, and pitch number, phase start and end, tap tooth sequence, channel identifier, and machining stage information are retained in the record entries. Amplitude variation features (increment or relative difference relative to the reference envelope), phase delay features (phase shift relative to the reference characteristic peak, or hysteresis angle obtained by cross-correlation), and attenuation features (the rate of attenuation of envelope energy within the phase window after disturbance removal, which can be approximated by half-amplitude time or logarithmic decrease rate) are extracted from the process response data and stored in conjunction with the phase interval and its machining stage information. Amplitude variation can reflect changes in load or friction state; phase delay can reveal the hysteresis of material response or meshing timing; and attenuation features can distinguish the difference in vibration fallback after plastic springback and chip impact. The three types of features are stored in an integrated manner with phase coordinates, channel and stage information, facilitating subsequent anomaly confirmation and directional process intervention within the same reference system. An equivalent implementation can represent attenuation characteristics as frequency domain energy redistribution, spectral centroid shift, or pulse density change; when bandwidth is limited, only the above feature vectors and corresponding phase indices are output, which can also support subsequent anomaly detection and parameter adjustment.

[0035] In one embodiment of the present invention, based on the correspondence between the tap rotation period and the axial feed, the start and end phase positions of the phase interval deviating from the threshold are registered, and the corresponding subsequent occurrence timing is generated, wherein: When machining with at least two taps in sequence, the first turn of the second tap after its entry is taken as the timing of the first subsequent appearance of the cutting shape; When the phase interval that deviates from the threshold is located at the bottom of the blind hole and the remaining number of cycles is insufficient to complete the disturbance action in this processing cycle, the subsequent occurrence of the phase interval will be postponed to the next processing cycle. When a single tap is used and its machining process includes both extrusion forming and cutting forming modes, the phase interval of the deviation threshold located in the extrusion forming stage will subsequently appear at the corresponding phase position when entering the same extrusion forming stage in the next pitch cycle; the phase interval of the deviation threshold located in the cutting forming stage will subsequently appear at the corresponding phase position when entering the same cutting forming stage in the next pitch cycle.

[0036] The following is a detailed description of the steps involved in the above embodiments: In scenarios where at least two taps (the first is a forming tap, and the second is a cutting tap) are used sequentially, the second tap's feed triggers a reset of the phase coordinate system. The phase position of the first revolution after feed is registered as the initial occurrence of the subsequent cutting shape. Specifically, when the second tap begins its feed, the reference pulse and axial position of the spindle encoder are read, and this moment is set as the zero point of the cutting shape's initial phase. The phase interval from the previously identified deviation threshold is mapped to the phase axis of the second tap in the form of a pitch phase angle. Within this first revolution, the controller issues pre-arranged tentative disturbances or process intervention commands according to the phase pre-trigger amount, ensuring the action accurately lands within the target phase window. If the two taps are driven by different spindles, a phase alignment handshake is performed before the second tap's feed, ensuring the phase zero point coincides with the feed moment, and the timing consistency of the commands is guaranteed by an event queue. This setting allows deviation information identified during the extrusion forming stage to be seamlessly transmitted to the first stable phase window during the cutting forming stage, avoiding phase misalignment across tools and ensuring continuous verification of the same working condition mechanism. An equivalent implementation can use the linkage between the spindle index signal and the feed arrival signal as the definition of the phase zero point, or set the phase zero point at a fixed phase angle before the arrival of the first stable load peak of the second tap. As long as the synchronization constraint with the pitch phase is maintained, the same effect can be achieved.

[0037] When a phase interval deviating from the threshold is located at the bottom of a blind hole and the remaining number of turns is insufficient to complete the disturbance action within the current machining cycle, the system postpones the subsequent occurrence of the phase interval to the next machining cycle. In implementation, the remaining distance between the current axial position and the bottom of the hole is calculated online and compared with the pitch and safety margin. When the remaining distance is less than the sum of the axial displacement covered by the target phase interval and the safety margin, it is determined that the remaining number of turns is insufficient. At this time, the start and end phase positions, tap sequence, and machining stage information of the phase interval are retained in the data structure, and a subsequent occurrence timing marker across workpieces is generated. This allows for the scheduling of trial disturbances or process interventions according to the marker after the phase zero point is established during the next hole machining. This strategy avoids the risk of tooth profile damage or tool collision caused by applying excitation at the bottom of the hole, while maintaining the continuity and traceability of anomaly diagnosis. An equivalent implementation can push the phase interval event to the same process at the next station on a multi-spindle rotary table, or write the event into a queue in a group control system, and execute it after the next workpiece enters the same process formula and the phase zero point is established.

[0038] When using a single tap (as shown in the attached image) Figure 2When the tap body (as shown) is processed in two modes, extrusion forming and cutting forming, the generation of subsequent occurrence timing is based on the processing stage: for phase intervals that deviate from the threshold in the extrusion forming stage, the subsequent occurrence timing is the corresponding phase position in the next pitch cycle when entering the same extrusion forming stage; for phase intervals that deviate from the threshold in the cutting forming stage, the subsequent occurrence timing is the corresponding phase position in the next pitch cycle when entering the same cutting forming stage. Specifically, a process mode label is attached to each phase point in the mapped phase dataset. After online detection of deviation, the phase interval and its mode label are registered together. The phase scheduler sets a pre-trigger angle before entering the same mode segment in the next cycle, and preloads the corresponding tentative disturbance or process intervention parameters. To avoid action overshooting caused by phase jitter, a dual threshold of phase jitter tolerance and minimum phase width can be set, and a small safety advance is added to the pre-trigger angle to ensure that the excitation always falls within the interval. This method utilizes the characteristic that the tap repeats the same extrusion and cutting sequence in each cycle, keeping the operated object within the same mechanism window and ensuring causal consistency between diagnosis and intervention. An equivalent implementation can change the pre-triggering angle from a fixed angle to an adaptive lead based on the correlation peak, or use the feed coverage as the criterion for entering the segment. As long as the synchronization with the pitch phase and the consistency of the mode label are guaranteed, the same timing and positioning accuracy can be obtained.

[0039] Please continue reading. Figure 1 Based on the correspondence between the process response data and the reference information, an abnormal phase interval is identified, and when the abnormal phase interval subsequently appears, a process intervention synchronized with the phase is performed. In one embodiment of the present invention, the step of identifying an abnormal phase interval based on the correspondence between the process response data and the reference information, and performing a phase-synchronized process intervention when the abnormal phase interval subsequently appears, includes: By comparing the process response data with the corresponding position of the reference information on the pitch phase mapping, abnormal phase intervals that match the preset deviation conditions are identified and confirmed. Based on the processing stage information corresponding to the abnormal phase interval and the amplitude change, phase delay or attenuation characteristics in the process response data, the abnormality is determined to be a material plasticity abnormality, chip generation abnormality or cooling chip removal abnormality, and an intervention parameter combination matching the abnormality type is determined. When the abnormal phase interval subsequently occurs, at least one process adjustment action from the intervention parameter combination is performed in a manner synchronized with the tap rotation and axial feed. Specifically, when the material plasticity is abnormal, the feed rate or medium pressure is adjusted; when chip generation is abnormal, the spindle speed or tool displacement is adjusted; and when cooling and chip removal are abnormal, the cooling medium pressure or flow direction is adjusted.

[0040] The following is a detailed description of the steps involved in the above embodiments: When confirming anomalies, the process response data is compared one-to-one with the corresponding positions of the reference information on the pitch phase mapping. The process response data comes from the process signals collected during the trial disturbance injected into the corresponding phase window, and has been mapped to the same phase resolution and tap tooth sequence index as the reference information according to the pitch phase. To avoid phase misalignment, the response data and the reference curve are aligned to the same zero phase within the target phase window using a phase alignment method before comparison. The amplitude difference, phase difference, and shape difference are calculated in the extrusion forming channel and the cutting forming channel respectively, and combined with the tolerance band of the phase point for judgment. The preset deviation conditions are defined as any one or more exceeding the limits: the amplitude difference exceeds the upper limit of the phase tolerance band, the phase difference exceeds the allowable phase offset window, and the shape difference (e.g., envelope consistency or inverse mean square error ratio) is lower than the preset threshold. Independent criteria are enabled in the process transition zone, requiring the energy ratio and slope continuity between channels to be within the allowable range. To suppress occasional noise, stability constraints of minimum phase width and repetition frequency are introduced, and hysteresis is added to the judgment logic to prevent edge samples from repeatedly flipping in adjacent loops. This process identifies and confirms abnormal phase intervals that match preset deviation conditions, outputting structured information such as their start and end phase angles, channel type, and tap sequence. An equivalent implementation can replace the calculation of morphological differences with peak-to-valley spacing consistency or pulse density consistency, or use the difference in frequency band energy proportion as a substitute indicator. As long as the determination is still performed in the phase coordinate system in conjunction with the tolerance band, the same confirmation effect can be achieved.

[0041] After confirming the abnormal phase interval, the abnormal mechanism is determined and the intervention parameter combination is established by combining the amplitude changes, phase delays, or attenuation characteristics in the corresponding machining stage information and process response data. The criterion for abnormal material plasticity is an increased amplitude response, significant phase delay, and slow attenuation after disturbance removal in the extrusion forming channel to low-frequency loads on feed or medium pressure pulsations, indicating restricted plastic flow or enhanced springback. In this case, the intervention parameter combination preferentially includes fine-tuning of the feed rate and medium pressure to reduce the deformation rate per unit volume or enhance lubrication and cooling to reduce frictional heating. The criterion for abnormal chip generation is an abnormal increase in the instantaneous response of high-frequency energy to spindle speed or feed rate pulsations in the cutting forming channel, with an impact-type decline in attenuation and a small phase delay, indicating unstable chip separation or intermittent discharge. In this case, the intervention parameter combination selects fine-tuning of the spindle speed or tool displacement, changing the cutting speed or instantaneous axial displacement correction to make the chip morphology easier to remove. The criterion for abnormal cooling chip removal is that the high-frequency energy is not significantly affected by velocity-type pulsations during the disturbance, but is sensitive to micro-pulsations in cooling medium pressure or flow direction, and the attenuation accelerates as the medium's contact time shortens, indicating that it is mainly controlled by cooling and flow field. In this case, the intervention parameter combination is to adjust the cooling medium pressure or flow direction. To ensure consistency, the parameter amplitude is set within a small range so that the excitation is sufficient to change the local mechanism without compromising tooth profile accuracy; a parameter trajectory with upper and lower limits and slope restrictions is preferred to avoid transient impacts. An equivalent implementation can use threshold rules as the core of the judgment process, or introduce robust statistical criteria (such as the combined use of quantile interval out-of-bounds and hysteresis) to form a combined decision, while still maintaining the correspondence between the three types of features derived to the three types of anomalies and mapped to the intervention parameter combination.

[0042] When an abnormal phase interval subsequently occurs, at least one process adjustment action from the intervention parameter combination is executed in a manner synchronized with tap rotation and axial feed. For abnormal material plasticity, a slight decrease in feed rate or a slight increase in medium pressure is performed within the target phase window during the extrusion forming stage. The parameter change is completed along a smooth acceleration / deceleration or S-shaped trajectory within the phase window, returning to the nominal value at the end of the window to ensure a reduction in load peak and a decrease in springback. For abnormal chip generation, a slight increase or decrease in spindle speed is performed during the cutting forming stage, or a small correction in tool displacement is superimposed within the phase window. This alters the instantaneous cutting speed and meshing conditions to promote chip breakage and smooth removal. For abnormal cooling and chip removal, the cooling medium pressure is increased or the nozzle flow direction is switched within the phase window to remove chips from the grooves and reduce local temperature rise. Intervention execution ensures landing point accuracy with phase pre-triggering and phase jitter tolerance, and process response data within the same phase window before and after intervention are recorded for closed-loop verification and subsequent condition updates. To accommodate equipment differences, intervention commands can be issued either by directly modifying the set value through the CNC system, by applying a small input through the superposition channel of the motion controller, or by issuing them through the programmable logic controller under phase interruption. As long as the constraint of synchronization with the pitch phase is met, the same timing and positioning effect can be obtained.

[0043] Please continue reading. Figure 1 Based on the phase data after process intervention, the output conditions for judging processing quality or process control are given.

[0044] In one embodiment of the present invention, the conditions for outputting the judgment of processing quality or process control based on the phase data after process intervention include: The phase data after process intervention are normalized according to pitch phase mapping, and intervention response feature values ​​are extracted, including amplitude difference, phase offset and frequency domain distribution change. The intervention response feature value is compared with the preset quality judgment standard and historical feature data under similar working conditions to determine whether the processing result belongs to the qualified, critical or unqualified level. Based on the judgment level, the corresponding process control conditions are output. When the level is qualified, the existing process parameters are maintained. When the level is critical, the feed rate or cooling medium pressure is adjusted. When the level is unqualified, a shutdown command is issued and the abnormal information corresponding to the operating condition is recorded for subsequent process optimization.

[0045] The following is a detailed description of the steps involved in the above embodiments: To perform normalization, the phase data acquired after the intervention is aligned to 0–360° phase coordinates and phase resolution consistent with the reference information under pitch phase mapping, and amplitude and time axis normalization is performed separately for each channel: the amplitude is calculated by converting the real-time amplitude into a relative increment using the reference envelope of the same phase segment before intervention; the time axis is corrected for minute speed fluctuations using the phase zero point and tooth sequence index to ensure a one-to-one correspondence between sampling points and phase grid points. Based on this, intervention response feature values ​​are extracted: amplitude difference is used to quantify the relative change of load or energy; phase offset is used to characterize the temporal lag of characteristic peaks after phase alignment; frequency domain distribution changes are characterized by the energy redistribution between frequency bands using the in-band energy ratio, spectral centroid position, or high / low frequency energy ratio. The above features are output separately for extrusion forming and cutting forming channels, along with pitch number, phase start and end, tap tooth sequence, and machining stage information to ensure consistency in subsequent comparisons. An equivalent implementation can use envelope energy and pulse density to replace frequency domain indicators. When bandwidth is limited, only feature vectors are output and the phase index is retained, which can still complete subsequent judgments.

[0046] In the quality assessment stage, the intervention response characteristic values ​​are compared item by item with the preset quality assessment criteria and historical characteristic data under similar working conditions. The quality assessment criteria are determined by comprehensively considering the tolerance band of the benchmark information, equipment noise, and control resolution, and a hysteresis band is set to prevent edge sample flipping. The historical characteristic data comes from the qualified machining records already recorded under the same tool, material, and process parameters. The assessment strategy is a composite decision: when the amplitude difference, phase offset, and frequency domain distribution change all fall within the corresponding phase tolerance band and meet the continuity constraint, it is judged as qualified; when any indicator is close to the upper / lower threshold and appears within a limited phase width, or when only a single indicator slightly exceeds the limit without forming a continuous segment, it is judged as critical; when multiple indicators exceed the limit and appear repeatedly in adjacent cycles, or when the continuity constraint is broken in the process transition zone, it is judged as unqualified. To accommodate material batch differences and tool dulling, small and robust fine-tuning of the threshold is allowed within the sliding window, but the data used for fine-tuning is isolated from the current cycle assessment data to ensure independent assessment. An equivalent implementation method can use the combined score of normalized correlation coefficient and mean square error as a morphological consistency index, or use the quantile interval boundary rule to achieve the same grading effect.

[0047] When outputting process control conditions, control commands synchronized with the pitch phase are generated based on the judgment level. For acceptable levels, existing process parameters are maintained, and only the intervention response characteristics and judgment results for this cycle are recorded for traceability. For critical levels, minor process adjustments are performed when the next phase of the corresponding machining stage occurs: in the extrusion forming channel, the feed rate is preferentially fine-tuned by -1% to -3% or the cooling medium pressure is increased by approximately 5% to 10%, using an S-shaped trajectory within the phase window and returning to the nominal value at the end of the window; in the cutting forming channel, the spindle speed can be fine-tuned by ±1% to ±3%, or a small tool displacement can be added to improve chip breakage and removal. For unacceptable levels, a stop command is immediately issued, retaining the abnormal phase interval, channel type, characteristic boundary details, and current equipment parameters as the basis for subsequent process optimization and pre-reset verification. To ensure equipment compatibility, control commands can be directly rewritten by the CNC system, or issued via the motion controller overlay channel or programmable logic controller under phase interruption; as long as the constraint of synchronization with the pitch phase is met, the same timing and positioning effects can be obtained.

[0048] This invention provides a thread extrusion system that employs the monitoring and feedback method in the thread forming process of any of the above embodiments, and therefore has the advantages of any of the above embodiments, which will not be elaborated here.

[0049] Furthermore, refer to Figure 2 and Figure 3 The extrusion thread system includes a tap body, which includes a connecting section 1, a cutting section 2, and an extrusion section 3 connected sequentially along its length. The connecting section 1 is used to connect to the machine tool spindle; The outer peripheral wall of the cutting section 2 includes a chip removal surface 21 and a threaded surface 22. The chip removal surface 21 is recessed with a chip removal groove 23 extending along the length direction of the cutting section 2. The threaded surface 22 is provided with a cutting thread portion 24. The tooth depth of the cutting thread portion 24 is not greater than the tooth depth of the internal thread of the workpiece to be processed. The cutting section 2 is used to remove part of the material at the tooth crest of the internal thread of the workpiece to be processed after the internal thread of the workpiece to be processed is extruded and formed to form a pre-formed thread profile and achieve chip removal. The outer peripheral wall of the extrusion section 3 is provided with an extrusion thread 31. The extrusion thread 31 cooperates with the inner peripheral wall of the pre-made hole of the workpiece to be processed during the extrusion stage of thread forming, and extrudes the inner peripheral wall of the pre-made hole to the target tooth shape and size.

[0050] Specifically, the connecting section 1 is the upper structure of the tap body, with a standardized clamping interface or threaded interface machined at one axial end for reliable connection with the tool holder or chuck of the machine tool spindle, and for transmitting the spindle's rotational torque and axial feed force during machining. The geometry and interface form of the connecting section 1 can be configured according to machine tool standards (such as BT, HSK, etc.) to ensure rigid installation and precise coaxiality under different equipment conditions, thereby reducing tooth profile errors caused by runout during machining.

[0051] The cutting section 2 is located between the connecting section 1 and the extrusion section 3, and its outer peripheral wall is alternately composed of a chip removal surface 21 and a threaded surface 22. The chip removal surface 21 has a chip removal groove 23 recessed along the axial direction, which extends through the pitch direction to smoothly guide the small chips generated during the cutting process to the outside of the workpiece, preventing chips from remaining in the thread forming area and causing surface scratches. The threaded surface 22 is machined with a cutting thread portion 24, the tooth depth of which is designed not to exceed the final tooth depth of the internal thread of the target workpiece. This allows for the removal of only excess material at the tooth crest during the secondary cutting after extrusion forming to form a precise pre-formed thread profile while maintaining a good chip removal channel. The function of this section is to improve the tooth crest shape and surface roughness through light cutting without compromising the integrity of the extruded tooth profile, and to remove residual chips.

[0052] The extrusion section 3 is located at the lowest end of the tap body, and its outer peripheral wall is provided with an extrusion thread portion 31 (in some embodiments, the chip removal groove 23 of the cutting section 2 can also extend to the outer peripheral wall of the extrusion section 3). The tooth profile of this thread portion corresponds to the target thread profile. In the initial extrusion stage of processing, it enters the inner peripheral wall of the pre-drilled hole in the workpiece, and through plastic deformation, the material flows to the tooth profile gap and fills the target contour and size, achieving chipless thread forming. The top diameter of the tooth profile of the extrusion section 3 is slightly larger than the pre-drilled hole diameter to ensure sufficient extrusion force. At the same time, the plasticity and elastic recovery characteristics of the material are considered in the design to prevent the tooth profile from springback beyond the tolerance range after forming.

[0053] The extrusion threaded part 31 and the cutting threaded part 24 mentioned above are both widely used structures. Their dimensions can be adjusted according to the actual workpiece processing needs, and will not be described in detail here.

[0054] This invention employs a tap body with an integrated structure of connecting section 1, cutting section 2, and extrusion section 3, enabling the extrusion and cutting forming functions to be completed continuously within the same tool. This eliminates the tool changing steps required in traditional processes, where an extrusion tap is used first, followed by a cutting tap. It is particularly suitable for fully enclosed or low-light (e.g., complete darkness) machining environments, avoiding positioning errors during manual tool changes, time losses due to machine tool reorientation, and the risk of scrap due to inaccurate cutting position determination, thereby significantly improving machining efficiency and product consistency.

[0055] In another embodiment, the system can also employ two separate taps, namely, an independent forming tap and a cutting tap, which are automatically switched or processed sequentially at different stages through program control. This solution is also feasible when it is necessary to optimize the forming and cutting parameters for different materials separately, or when the machine tool has a highly efficient automatic tool changer system. It can flexibly cope with various working conditions while maintaining the advantages of the core monitoring and feedback method of this invention.

[0056] This invention also provides an application of extruded threads. It should be noted that any workpiece processed by the monitoring and feedback method in the above-mentioned thread forming process belongs to the application of extruded threads.

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A monitoring and feedback method for the thread forming process, characterized in that, include: During the thread forming process, a sampling method synchronized with the tap rotation and feed is used to acquire process signals, and the process signals are mapped according to the pitch phase to obtain a mapped phase dataset and real-time phase data for online comparison. The mapping phase dataset is used to form reference information for determining the processing status, and the real-time phase data is compared with the reference information during the processing to identify the phase intervals that deviate from the threshold. Record the timing of the occurrence of the phase interval that deviates from the threshold in subsequent processing, and apply a tentative perturbation at the timing of the occurrence, and collect the process response data after the perturbation; Based on the correspondence between the process response data and the reference information, an abnormal phase interval is identified, and when the abnormal phase interval subsequently appears, process intervention synchronized with the phase is performed. Specifically, this includes: comparing the corresponding positions of the process response data and the reference information on the pitch phase mapping to identify and confirm abnormal phase intervals that match preset deviation conditions; based on the processing stage information corresponding to the abnormal phase interval and the amplitude change, phase delay, or attenuation characteristics in the process response data, determining whether the abnormality belongs to material plasticity abnormality, chip generation abnormality, or cooling chip removal abnormality, and determining an intervention parameter combination that matches the abnormality type; when the abnormal phase interval subsequently appears, at least one process adjustment action in the intervention parameter combination is performed in a manner synchronized with tap rotation and axial feed, wherein, when there is a material plasticity abnormality, the feed rate or medium pressure is adjusted; when there is a chip generation abnormality, the spindle speed or tool displacement is adjusted; and when there is a cooling chip removal abnormality, the cooling medium pressure or flow direction is adjusted. Based on the phase data after process intervention, output the conditions for judging processing quality or process control.

2. The monitoring and feedback method for the thread forming process according to claim 1, characterized in that, The process signal is mapped according to pitch phase to obtain a mapped phase dataset and real-time phase data for online comparison, including: The process signals are divided into subsets related to material plastic flow and subsets related to chip generation based on signal characteristics. Pitch phase segmentation mapping is performed in combination with tap tooth sequence to obtain dual-channel phase mapping results corresponding to extrusion forming and cutting forming. A process transition window is set with the extrusion forming end phase and the cutting forming start phase as the boundary, and phase alignment and continuity constraints are performed on the dual-channel phase mapping results within the process transition window, wherein the first circle phase of the second infeed is taken as the cutting forming start phase; After phase alignment is completed, process mode labels and material response tags are attached to each phase position, and the labels are bound and stored with the process signals of the corresponding phase positions to generate a mapped phase dataset with associated object attributes. While generating the mapped phase dataset, the phase data corresponding to the current processing cycle is extracted as real-time phase data.

3. The monitoring and feedback method for the thread forming process according to claim 1, characterized in that, The step of forming reference information for determining the processing state based on the mapped phase dataset, and comparing the real-time phase data with the reference information during processing to identify phase intervals deviating from a threshold, includes: Based on the phase data corresponding to the extrusion forming stage and the cutting forming stage in the mapped phase dataset, a dual-channel reference information set is constructed, and an independent set of discrimination parameters is established in the process transition zone from the end of extrusion to the start of cutting. During the processing, the real-time phase data is aligned with the reference information of the corresponding stage according to the phase position, and the amplitude, phase difference and waveform shape are compared in the normal phase area and the process transition area respectively to determine whether it deviates from the threshold. The phase interval of real-time phase data that is determined to deviate from the threshold is located, and the phase interval deviating from the threshold and the processing mode information corresponding to the phase interval deviating from the threshold are output.

4. The monitoring and feedback method for the thread forming process according to claim 1, characterized in that, The process records the timing of the occurrence of the phase interval deviating from the threshold during subsequent processing, applies a tentative perturbation at the timing of the occurrence, and collects process response data after the perturbation, including: Based on the correspondence between the tap rotation period and the axial feed, the start and end phase positions of the phase interval that deviates from the threshold are registered, and the corresponding subsequent occurrence timing is generated. Based on the processing stage information corresponding to the phase interval that deviates from the threshold, a trial disturbance synchronized with the phase is performed within the subsequent occurrence time: when the phase interval that deviates from the threshold is in the extrusion forming stage, a micro-pulse is applied to the feed or medium pressure to elicit a material plastic or springback response; when the phase interval that deviates from the threshold is in the cutting forming stage, a micro-pulse is applied to the spindle speed or feed rate to elicit a chip generation or chip removal response. During the exploratory disturbance, disturbance response process signals are acquired within the time window corresponding to the phase interval that deviates from the threshold, and corresponding process response data are formed according to pitch phase mapping. Amplitude change features, phase delay features, or attenuation features in the process response data are extracted, and the amplitude change features, phase delay features, or attenuation features are bound and stored with the phase interval that deviates from the threshold and its corresponding processing stage information for subsequent anomaly confirmation and directional process intervention.

5. The monitoring and feedback method for the thread forming process according to claim 4, characterized in that, Based on the correspondence between the tap rotation period and the axial feed, the start and end phase positions of the phase interval deviating from the threshold are registered, and the corresponding subsequent occurrence timing is generated, wherein: When machining with at least two taps in sequence, the first turn of the second tap after its entry is taken as the timing of the first subsequent appearance of the cutting shape; When the phase interval that deviates from the threshold is located at the bottom of the blind hole and the remaining number of cycles is insufficient to complete the disturbance action in this processing cycle, the subsequent occurrence of the phase interval will be postponed to the next processing cycle. When a single tap is used and its machining process includes both extrusion forming and cutting forming modes, the phase interval of the deviation threshold located in the extrusion forming stage will subsequently appear at the corresponding phase position when entering the same extrusion forming stage in the next pitch cycle; the phase interval of the deviation threshold located in the cutting forming stage will subsequently appear at the corresponding phase position when entering the same cutting forming stage in the next pitch cycle.

6. The monitoring and feedback method for the thread forming process according to claim 1, characterized in that, The conditions for judging processing quality or controlling the process based on the phase data after process intervention include: The phase data after process intervention are normalized according to pitch phase mapping, and intervention response feature values ​​are extracted, including amplitude difference, phase offset and frequency domain distribution change. The intervention response feature value is compared with the preset quality judgment standard and historical feature data under similar working conditions to determine whether the processing result belongs to the qualified, critical or unqualified level. Based on the judgment level, the corresponding process control conditions are output. When the level is qualified, the existing process parameters are maintained. When the level is critical, the feed rate or cooling medium pressure is adjusted. When the level is unqualified, a shutdown command is issued and the abnormal information corresponding to the operating condition is recorded for subsequent process optimization.

7. A calendered thread system, characterized in that, The extrusion thread system employs the monitoring and feedback methods described in claims 1 to 6 during the thread forming process.

8. The extrusion thread system as described in claim 7, characterized in that, The extrusion thread system includes a tap body, which includes a connecting section, a cutting section, and an extrusion section connected sequentially along its length. The connecting section is used to connect to the machine tool spindle; 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 tooth depth of the cutting thread portion is not greater than the tooth depth of the internal thread of the workpiece to be processed. The cutting section is used to remove part of the material at the tooth crest of the internal thread of the workpiece to be processed after the internal thread of the workpiece to be processed is extruded and formed to form a pre-formed thread profile and achieve chip removal. The outer peripheral wall of the extrusion section is provided with an extrusion thread. The extrusion thread cooperates with the inner peripheral wall of the pre-drilled hole of the workpiece to be processed during the extrusion stage of thread forming, and extrudes the inner peripheral wall of the pre-drilled hole to the target tooth shape and size.

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