A polishing method for precision part machining

Abstract

The present application relates to the technical field of processing and polishing, and particularly relates to a polishing method for precision part processing, which comprises the following steps: extracting flow resistance characteristic values and flow resistance change rates and flow resistance accelerations thereof based on large-hole end inlet pressure and medium real-time flow; determining medium flow state based on the flow resistance change rates and predicting flow resistance change trend combining the flow resistance accelerations; determining the flow resistance component contributed by the small-hole section based on the flow resistance contribution proportion of the small-hole section and the flow resistance characteristic values, and determining the small-hole section aperture change trend index combining the change rate of the flow resistance component, adjusting the large-hole end inlet pressure according to the polishing influence degree of the part small-hole section; obtaining the small-hole section aperture change trend index and aperture expansion rate safety threshold value, calculating threshold deviation index, adjusting the change threshold value of the flow resistance change rate. The present application predicts the flow resistance characteristic trend and combines the deterioration mechanism to understand the polishing state of the coupling hole section, realizes the polishing control of the variable-diameter micro-channel, efficiently removes the knife marks, prevents the aperture from being out of tolerance and polishing stagnation, and removes the variable-diameter step burrs.

Description

Technical Field

[0001] This invention relates to the field of machining and polishing technology, and in particular to a polishing method for machining precision parts. Background Technology

[0002] With the rapid development of thermal management technologies in aerospace, nuclear energy, and high-end electronic equipment, microchannel heat exchangers have become core components of thermal control systems due to their efficient and compact heat exchange performance. To achieve higher heat exchange efficiency and lighter weight, the internal flow channels of these heat exchangers often employ complex structural designs such as variable diameter and stacked layers. The quality of their internal surface machining directly determines flow resistance characteristics, heat exchange efficiency, and long-term service reliability. When drilling is used to machine these microchannel holes, the following prominent problems commonly exist on the internal surface: First, the spiral tool marks (tool marks) left by the tool on the hole wall surface during drilling result in high surface roughness; second, at the root of the step where the diameter abruptly changes from large to small, burrs and flanges are easily generated, severely altering the local flow area and distorting the designed flow resistance characteristics; third, due to the pushing action of the drill bit during penetration, the edge of the outlet small hole section often exhibits curling and minor chipping. If these problems are not effectively eliminated, they will not only increase flow resistance and reduce heat exchange efficiency, but the detached burrs and debris may also enter the downstream pipeline with the working medium, causing serious failures such as blockage or component wear.

[0003] For the subsequent polishing of microchannel internal pores, abrasive flow polishing is a relatively mature technology. It removes material from the inner wall by driving a viscoelastic medium containing hard abrasive particles to flow back and forth within the channel. However, existing abrasive flow polishing technologies are mainly designed for channels with constant or gradually changing cross-sections, defaulting to bidirectional symmetrical flow parameters. When dealing with variable-diameter microchannels exhibiting "end-throttling" characteristics, significant limitations exist: when the medium flows from the larger orifice to the smaller orifice, the outlet throttling effect leads to a sudden increase in velocity and a sudden drop in pressure, easily inducing cavitation at the diameter change step, generating cavitation pits and compromising the orifice diameter accuracy; conversely, when feeding material from the smaller orifice in the reverse direction, the throttling effect of the orifice inlet on the abrasive medium results in insufficient abrasive distribution in the deeper main channel, leading to low polishing efficiency in the larger orifice section. Furthermore, oxygen-free copper is relatively soft and chemically reactive, easily causing scratches and oxidation discoloration during polishing, further increasing the process difficulty.

[0004] Chinese Patent Publication No. CN101224556A discloses a magnetorheological precision polishing system and method for optical components. By changing the polishing head of different shapes and specifications according to the shape of the workpiece, and through a computer-controlled automatic control device, the viscosity and temperature of the magnetorheological liquid can be controlled. Changing factors such as the magnetic field and rotation speed can achieve different polishing efficiencies and precisions. However, the aforementioned magnetorheological precision polishing system and method for optical components has the following problems: It is impossible to simultaneously achieve efficient removal of drill marks in the straight section of the microchannel under drilling of asymmetric variable diameter structures and protection of the hole diameter accuracy of the end throttling section. During the processing, the mechanism of abrasive particle aggregation, cavitation erosion and debris geometric blockage is differentiated and controlled in real time. The polishing states of the large hole section and the small hole section are decoupled to achieve independent adjustment and closed-loop optimization of the two sections. Summary of the Invention

[0005] Therefore, the present invention provides a polishing method for precision component machining, which overcomes the problem in the prior art that it is impossible to simultaneously remove drilling marks in the straight section of an asymmetric variable diameter structure and protect the diameter accuracy of the throttling section, and to decouple the differential control of polishing states between the large and small hole sections from the mechanism of blockage abnormality in the machining process.

[0006] To achieve the above objectives, the present invention provides a polishing method for precision component machining, comprising: Based on the inlet pressure at the large orifice end and the real-time flow rate of the medium, the characteristic values ​​of flow resistance, as well as the rate of change of flow resistance and the acceleration of flow resistance are extracted. The flow state of the medium is determined based on the rate of change of flow resistance, and the trend of flow resistance change is predicted by combining the acceleration of flow resistance. In response to the trend of flow resistance change, the degree of flow resistance reduction or the temperature rise flow resistance coupling coefficient and temperature rise energy ratio are determined based on the flow resistance characteristic value. The temperature rise flow resistance coupling coefficient is determined based on the obtained medium temperature rise rate combined with the flow resistance change rate, and the temperature rise energy ratio is determined based on the outlet medium temperature combined with the real-time ultrasonic power. The trend of the change in the energy ratio of the temperature rise energy ratio is obtained, and the type of trend deterioration is determined by combining the temperature rise flow resistance coupling coefficient, and the trend deterioration is distinguished as geometric blockage and cavitation cavitation. In response to the deterioration trend, adjust the inlet pressure and ultrasonic power at the large orifice end, or obtain the long-term sliding average of the temperature based on the medium temperature at the outlet end, and determine the temperature fluctuation intensity ratio by combining the temperature fluctuation intensity to piecewise linearly map the flow resistance contribution ratio of the small orifice section. The flow resistance contribution of the small orifice section is determined by combining the proportion of flow resistance contribution of the small orifice section with the flow resistance characteristic value, and the flow resistance component is combined with the rate of change of the flow resistance component to determine the trend index of the orifice diameter change of the small orifice section, and the polishing influence of the small orifice section of the component is determined to adjust the inlet pressure of the large orifice end. The intensity of ultrasonic power fluctuation is used to determine the roughness improvement trend of the large hole section, so as to determine the degree of polishing influence of the large hole section of the component and adjust the ultrasonic power accordingly. Obtain the orifice diameter change trend index and orifice diameter expansion rate safety threshold, calculate the threshold deviation index, and adjust the change threshold of flow resistance change rate.

[0007] Furthermore, the process of determining the flow state of the medium includes: If the absolute value of the rate of change of flow resistance is less than or equal to the change threshold, the medium flow state is judged to be normal. If the absolute value of the rate of change of flow resistance is greater than the threshold value, it is determined that the change in the medium flow state is out of range, and the trend of flow resistance change is predicted by combining the flow resistance acceleration.

[0008] Furthermore, the process of predicting the trend of flow resistance changes includes: If the rate of change of flow resistance is greater than zero and the flow resistance acceleration is less than the negative acceleration threshold, then the predicted flow resistance change trend tends to stabilize, and the sampling frequency should be increased. If the rate of change of flow resistance is greater than zero and the flow resistance acceleration is greater than or equal to a negative acceleration threshold, the flow resistance change trend is predicted to worsen, indicating a risk of blockage or cavitation. When the rate of change of flow resistance is less than zero, the predicted trend of flow resistance change is relaxed, the channel resistance decreases and tends to be unobstructed, and the flow resistance characteristic value is used to determine whether the flow resistance decrease is excessive. If the flow resistance characteristic value is lower than the critical lower limit of the initially calibrated characteristic threshold, it is determined that there is a risk of excessive removal of material in the large-pore section, and the standard amplitude of the inlet pressure at the large-pore end is reduced.

[0009] Furthermore, the process of determining the type of trend deterioration includes; If the temperature rise flow resistance coupling coefficient is greater than the first coefficient threshold and the energy ratio change trend is greater than zero, the trend deterioration is judged to be internal friction-dominated deterioration. If the temperature rise flow resistance coupling coefficient is less than the first coefficient threshold or the energy ratio change trend is less than zero, then the trend deterioration is distinguished as geometric blockage and cavitation cavitation.

[0010] Furthermore, the process of distinguishing the deteriorating trend includes: If the temperature rise flow resistance coupling coefficient is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is greater than the fluctuation threshold, the trend deterioration is judged to be cavitation cavitation-dominated deterioration. If the temperature rise flow resistance coupling coefficient is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is less than or equal to the fluctuation threshold, the trend deterioration is judged to be geometric blockage-dominated deterioration.

[0011] Furthermore, the trend deteriorates into an internal friction-dominated deterioration, reducing the standard amplitude of the inlet pressure at the large orifice end and decreasing the flow velocity and shear rate at the component diameter change point; The trend worsens to cavitation cavitation-dominated deterioration, and the ultrasonic power is reduced by a preset percentage based on the reference power. The trend deteriorated into a geometric blockage-dominated deterioration, determining the degree of polishing impact on large and small hole segments within the part.

[0012] Furthermore, the temperature moving average is obtained by taking the arithmetic mean of the temperature values ​​of the current sampling point and several consecutive sampling points before it, and the temperature fluctuation intensity is obtained based on the root mean square value of the difference between several sampling points and the temperature moving average. If the temperature fluctuation intensity ratio is greater than or equal to the first intensity ratio threshold, it is determined that the flow resistance change is mainly contributed by the orifice, and the flow resistance contribution ratio is the maximum value of the flow resistance contribution ratio. If the temperature fluctuation intensity ratio is less than or equal to the second intensity ratio threshold, it is determined that the flow resistance change is mainly contributed by the large orifice, and the flow resistance contribution ratio is the minimum value of the flow resistance contribution ratio. If the temperature fluctuation intensity ratio is less than the first intensity ratio threshold and greater than the second intensity ratio threshold, then the flow resistance contribution ratio is a linear interpolation between the minimum and maximum flow resistance contribution ratios according to the ratio of the temperature fluctuation intensity ratio.

[0013] Furthermore, the process of adjusting the inlet pressure at the large orifice end includes: If the orifice diameter change trend index of the small orifice section is less than the negative safety threshold or the flow resistance component contributed by the small orifice section is less than the critical flow resistance value, it is judged that the small orifice section has a risk of exceeding the upper limit of tolerance. The inlet pressure of the large orifice end is reduced according to the absolute value of the ratio of the orifice diameter change trend index of the small orifice section to the safety threshold.

[0014] Furthermore, the power fluctuation intensity is the ratio of the standard deviation to the mean of the real-time ultrasonic power; If the roughness improvement trend of the large hole section is greater than or equal to the target polishing efficiency, then the polishing of the large hole section is considered effective. If the improvement trend of roughness in the large hole section is less than the target polishing efficiency, it is determined that the polishing of the large hole section has stalled, and the ultrasonic power is increased according to the ratio of the improvement trend of roughness in the large hole section to the target polishing efficiency.

[0015] Furthermore, the threshold deviation index is the ratio of the absolute value of the trend index of the aperture change in the small aperture segment to the safe threshold of the aperture expansion rate. When the threshold deviation index is less than the second index threshold, it is determined that the threshold deviation index is too small, and the threshold for the change in flow resistance rate is increased. If the threshold deviation index is greater than or equal to the first index threshold, it is determined that the threshold deviation index is too large, and the threshold for the change rate of flow resistance is reduced.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By real-time acquisition of inlet pressure, flow rate, temperature, and ultrasonic power, this invention constructs flow resistance characteristic values ​​and their rate of change and acceleration, enabling multi-level online identification and trend prediction of the polishing state inside the microchannel. When the flow resistance change trend is abnormal, the invention accurately distinguishes three types of deterioration mechanisms—internal friction-dominated, cavitation cavitation, and geometric blockage—using the temperature rise flow resistance coupling coefficient and temperature rise energy ratio and their change trends. For geometric blockage, the invention further decouples the polishing contribution of the large-diameter and small-diameter sections by using the temperature sliding mean and fluctuation intensity, independently evaluating the aperture change rate of the small-diameter section and the roughness improvement process of the large-diameter section. Based on this, the invention quantitatively adjusts the inlet pressure according to the deviation between the aperture change trend index of the small-diameter section and the safety threshold, and quantitatively adjusts the ultrasonic power according to the deviation between the roughness improvement trend of the large-diameter section and the target efficiency. The invention also corrects the flow resistance change threshold through negative feedback of the threshold deviation index, achieving closed-loop control. This ensures the uniformity of polishing quality in each section of the variable-diameter microchannel while effectively avoiding aperture deviation and surface damage.

[0017] Furthermore, this invention achieves online identification of the polishing state inside the microchannel by real-time acquisition of inlet pressure, medium flow rate, and outlet temperature, calculation of flow resistance characteristic values ​​and their first-order rate of change and second-order acceleration, and combining this with the medium temperature rise rate. When the flow resistance rate of change exceeds the threshold, based on its combined trend with the flow resistance acceleration, the flow state is classified into three categories: stabilization, deterioration, and relaxation, and differentiated responses are adopted respectively, such as increased sampling, pressure reduction protection, or in-depth diagnostics. This method can promptly detect abnormal trends such as abrasive particle aggregation, debris accumulation, or cavitation erosion during the removal of drilling marks and burrs on variable diameter steps, avoiding excessive material removal in large-diameter sections and out-of-tolerance diameter removal in small-diameter sections. While ensuring the uniformity of surface quality in each section of the variable-diameter microchannel, it effectively reduces the risk of workpiece scrap.

[0018] Furthermore, when the flow resistance change trend is determined to be deteriorating, the ultrasonic power is introduced in combination with the temperature rise flow resistance coupling coefficient and the temperature rise energy ratio and their changing trends. The deterioration mechanism is further divided into three categories: internal friction-dominated, cavitation cavitation-dominated, and geometric blockage-dominated. By identifying the significance of the additional temperature rise during the flow resistance increase process and the stability of ultrasonic energy transfer, it is possible to accurately distinguish the increase in medium viscosity caused by abrasive particle aggregation, the intermittent absorption and scattering of ultrasound by cavitation bubble groups, and the pure geometric accumulation of drilling burrs and debris. Differentiated measures such as pressure and speed reduction, reduction of ultrasonic power, or entry into two-stage decoupling evaluation are adopted for different mechanisms to avoid ineffective adjustment or reverse damage caused by misjudgment. This achieves accurate diagnosis and targeted intervention for abnormal polishing of variable diameter microchannels.

[0019] Furthermore, after determining that the deterioration is dominated by geometric blockage, this invention constructs a temperature fluctuation intensity ratio by using a long-window moving average and a short-window root mean square fluctuation of temperature. A piecewise linear mapping is then used to decouple the total flow resistance into the respective contributions of the large-diameter and small-diameter sections, thereby calculating the aperture change trend index of the small-diameter section. Simultaneously, the sliding window fluctuation intensity of ultrasonic power is used to assess the roughness improvement trend of the large-diameter section, achieving independent judgment of the polishing process of the large-diameter section and the aperture state of the small-diameter section. This method utilizes only existing temperature and ultrasonic power signals, without the need for additional sensors, to identify polishing stagnation in the large-diameter section and the risk of aperture deviation in the small-diameter section. Based on the deviation from the target polishing efficiency, the ultrasonic power is quantitatively adjusted; based on the deviation from the safety threshold, the inlet pressure is quantitatively adjusted, achieving differentiated and precise control of the large-diameter and small-diameter sections, avoiding insufficient efficiency or aperture deviation caused by blind adjustment.

[0020] Furthermore, this invention constructs a threshold deviation index by calculating the ratio of the orifice diameter change trend index to the safety threshold, and compares it with the tolerance range to determine the sensitivity of the current flow resistance change threshold. When the deviation index is too small, it indicates that the threshold is too small and too sensitive to normal fluctuations, so the threshold is increased to reduce false triggering. When the deviation index is too large, it indicates that the threshold is too large and anomalies are not captured in time, so the threshold is decreased to improve detection sensitivity. The negative feedback adjustment mechanism makes the flow resistance change threshold continuously approach the optimal range during the processing, taking into account both the timeliness of anomaly detection and anti-interference ability. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for precision component machining and polishing in an embodiment of the present invention; Figure 2 This is a front view of the left end face of the precision component in an embodiment of the present invention; Figure 3 This is a front view of the right end face of the precision component in an embodiment of the present invention; Figure 4 This is a top view of the left end face of the precision component in an embodiment of the present invention; Figure 5 This is a bottom view of the right end face of the precision component in an embodiment of the present invention; Figure 6 This is a side view of the precision component substrate in an embodiment of the present invention; In the figure: 1-left end face, 2-right end face, 3-substrate side, 4-microchannel hole, 5-first mounting hole, 6-second mounting hole. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0025] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Please see Figures 1-6 As shown, Figure 1 This is a flowchart of a method for precision component machining and polishing in an embodiment of the present invention; Figure 2 This is a front view of the left end face of the precision component in an embodiment of the present invention; Figure 3 This is a front view of the right end face of the precision component in an embodiment of the present invention; Figure 4 This is a top view of the left end face of the precision component in an embodiment of the present invention; Figure 5 This is a bottom view of the right end face of the precision component in an embodiment of the present invention; Figure 6 This is a side view of the precision component substrate in an embodiment of the present invention.

[0027] This invention provides a polishing method for precision component machining, comprising: Step S1: Extract the flow resistance characteristic value, its flow resistance change rate, and flow resistance acceleration based on the inlet pressure at the large orifice end and the real-time flow rate of the medium. Determine the medium flow state based on the flow resistance change rate and predict the flow resistance change trend based on the flow resistance acceleration. Step S2: In response to the trend of flow resistance change, determine the degree of flow resistance reduction or determine the temperature rise flow resistance coupling coefficient and temperature rise energy ratio based on the flow resistance characteristic value; The temperature rise flow resistance coupling coefficient is determined based on the obtained medium temperature rise rate combined with the flow resistance change rate, and the temperature rise energy ratio is determined based on the outlet medium temperature combined with the real-time ultrasonic power. Step S3: Obtain the energy ratio change trend of the temperature rise energy ratio, combine it with the temperature rise flow resistance coupling coefficient to determine the trend deterioration type, and distinguish the trend deterioration as geometric blockage and cavitation cavitation. Step S4: Adjust the inlet pressure and ultrasonic power at the large orifice end in response to the trend deterioration type, or obtain the long-term sliding average of the temperature based on the medium temperature at the outlet end, and determine the temperature fluctuation intensity ratio by combining the temperature fluctuation intensity to piecewise linearly map the flow resistance contribution ratio of the small orifice section. Step S5: Based on the proportion of flow resistance contribution of the small orifice section and the flow resistance characteristic value, determine the flow resistance component contributed by the small orifice section, and determine the orifice diameter change trend index by combining the change rate of the flow resistance component, determine the polishing influence of the small orifice section of the component, and adjust the inlet pressure at the large orifice end. Step S6: Obtain the power fluctuation intensity of the ultrasonic power to determine the roughness improvement trend of the large hole section, so as to determine the polishing influence of the large hole section of the component and adjust the ultrasonic power. Step S7: Obtain the orifice diameter change trend index and orifice diameter expansion rate safety threshold, calculate the threshold deviation index, and adjust the change threshold of flow resistance change rate.

[0028] Specifically, this invention acquires in-real-time inlet pressure, flow rate, temperature, and ultrasonic power to construct flow resistance characteristic values ​​and their rate of change and acceleration, enabling multi-level online identification and trend prediction of the polishing state inside the microchannel. When the flow resistance change trend is abnormal, the invention accurately distinguishes three deterioration mechanisms—internal friction-dominated, cavitation cavitation, and geometric blockage—by utilizing the temperature rise flow resistance coupling coefficient and temperature rise energy ratio and their change trends. For geometric blockage, the invention further decouples the polishing contribution of the large-diameter and small-diameter sections by using the temperature sliding mean and fluctuation intensity, independently evaluating the aperture change rate of the small-diameter section and the roughness improvement process of the large-diameter section. Based on this, the invention quantitatively adjusts the inlet pressure according to the deviation between the aperture change trend index of the small-diameter section and the safety threshold, and quantitatively adjusts the ultrasonic power according to the deviation between the roughness improvement trend of the large-diameter section and the target efficiency. The invention also corrects the flow resistance change threshold through negative feedback of the threshold deviation index, achieving closed-loop control. This ensures the uniformity of polishing quality in each section of the variable-diameter microchannel while effectively avoiding aperture deviation and surface damage.

[0029] In this embodiment, the workpiece is a variable-diameter stacked microchannel heat exchanger made of oxygen-free copper, with a non-uniform cross-section stepped cuboid structure. The base side has three parallel horizontal seams, and the end face is the main fluid inlet / outlet and mounting surface.

[0030] Microchannel holes are provided in the core area of ​​the substrate end face. The microchannel holes are arranged in two standard parallel and equidistant rows. The number of holes on the left and right ends is exactly the same and they correspond one-to-one and are coaxial. The microchannel holes on the left end face are large-diameter sections with uniform apertures; the microchannel holes on the right end face are small-diameter sections with uniform apertures that are smaller than the apertures on the left end face; each microchannel hole is a single-hole variable-diameter structure, abruptly transitioning from a large hole on the left end to a small hole on the right end. Specifically, each of the microchannel holes includes a large-diameter segment and a small-diameter segment arranged sequentially along the fluid flow direction; the length of the large-diameter segment accounts for more than 80% of the total length of the microchannel hole, and the length of the small-diameter segment is less than 20% of the total length of the microchannel hole; the large-diameter segment and the small-diameter segment are separated by a step surface with a sudden change in diameter.

[0031] The base has symmetrically distributed mounting holes at its corners. The mounting holes include a first mounting hole and a second mounting hole. The first mounting hole is a variable diameter structure that penetrates the workpiece base, and the second mounting hole is a non-penetrating structure located on the left end face.

[0032] Specifically, the mounting holes are large-diameter through holes symmetrically distributed at both ends of the end face, with a diameter larger than the central microchannel hole, used for installing fixing bolts or connecting liquid cooling pipe joints; The microchannel holes are located in the core area in the middle of the end face. Dozens of small-diameter circular through holes are distributed in a regular matrix-like staggered arrangement. All the holes are completely connected along the length of the part. The dense microchannel structure can greatly increase the heat exchange area between the fluid and the copper substrate, and significantly improve the heat dissipation efficiency.

[0033] In this embodiment, an ultrasonic-assisted abrasive flow polishing method is used.

[0034] The flow resistance change rate kR and the flow resistance acceleration aR are obtained based on the flow resistance characteristic value Rf. The flow resistance characteristic value Rf is extracted based on the inlet pressure P1 at the large orifice end and the real-time flow rate Q of the medium, and is the ratio of the inlet pressure P1 at the large orifice end to the real-time flow rate Q of the medium. The flow resistance characteristic value Rf reflects the overall resistance of the channel to the fluid; when the channel geometry remains unchanged and the medium viscosity is stable, the flow resistance characteristic value Rf is a constant; when blockage, abrasive accumulation, or changes in wall roughness occur, the flow resistance characteristic value Rf increases.

[0035] The flow resistance change rate kR is determined based on the change in the flow resistance characteristic value Rf between sampling points and the sliding window, and the flow resistance acceleration aR is determined based on the change in the flow resistance change rate kR between sampling points and the sliding window. In practice, the flow resistance change rate kR is determined based on the ratio of the difference between the current sampling point and the flow resistance characteristic value Rf five sampling points ago to the corresponding sliding window, thus suppressing single-point noise interference. The flow resistance acceleration aR is determined by the ratio of the difference between the current sampling point and the flow resistance change rate kR five sampling points ago to the corresponding sliding window. A flow resistance acceleration aR greater than zero indicates that the flow resistance is not only increasing, but also increasing faster and faster, and the deterioration is accelerating. A flow resistance acceleration aR less than zero indicates that although the flow resistance is increasing, the rate of increase is slowing down and tending to stabilize.

[0036] If the absolute value of the flow resistance change rate kR is less than or equal to the change threshold, then the medium flow state is judged to be normal. If the absolute value of the flow resistance change rate kR is greater than the change threshold, it is determined that the medium flow state has changed significantly. The flow resistance change trend is predicted based on the flow resistance change rate kR combined with the flow resistance acceleration aR.

[0037] Specifically, if the rate of change of flow resistance kR is greater than zero and the flow resistance acceleration aR is less than the negative acceleration threshold, then the predicted flow resistance change trend tends to stabilize, and the sampling frequency is adjusted. If the rate of change of flow resistance is greater than zero and the acceleration of flow resistance aR is greater than or equal to a negative acceleration threshold, then the trend of flow resistance change is predicted to worsen, and there is a risk of blockage or cavitation. When the rate of change of flow resistance kR is less than zero, the predicted flow resistance change trend is relaxed, the channel resistance decreases and tends to be unobstructed, and the flow resistance characteristic value Rf is used to determine whether the flow resistance decrease is excessive.

[0038] Understandably, during normal polishing, the flow resistance characteristic value Rf changes slowly within the range of 5~25 Pa·s / ml, and the flow resistance change rate kR is usually between 0.03~0.08 Pa·s / (ml·s). When blockage or cavitation occurs, the flow resistance change rate kR exceeds 0.1. Therefore, the preferred value range of the change threshold is 0.1~0.2 Pa / ml, which can effectively distinguish between normal slow change and abnormality. Under normal operating conditions, the flow resistance acceleration fluctuates slightly near zero, and the absolute value usually does not exceed 0.02. When the deterioration stabilizes, the flow resistance acceleration turns from positive to negative. It is necessary to reach the preferred value range of 0.02~0.04 of the acceleration threshold to confirm that the growth rate has substantially slowed down. Taking this range can achieve a balance between avoiding misjudgment and timely confirmation of stabilization.

[0039] Specifically, during the abrasive flow polishing process, the inlet pressure P1 at the large orifice end is collected in real time by a pressure sensor, the real-time flow rate Q of the medium is collected in real time by a flow sensor, and the outlet temperature T of the medium is collected in real time by a temperature sensor. The sampling frequency is ≥20Hz.

[0040] The flow resistance characteristic value Rf is extracted based on the inlet pressure P1 at the large orifice end and the real-time flow rate Q of the medium. The flow resistance characteristic value Rf is determined based on the ratio of the inlet pressure P1 at the large orifice end to the real-time flow rate Q of the medium.

[0041] The medium temperature rise rate kT is determined based on the outlet medium temperature T. The medium temperature rise rate kT is determined based on the change in outlet medium temperature T between sampling points and the sliding window. The medium temperature rise rate kT is determined based on the ratio of the difference between the current sampling point and the outlet medium temperature T five sampling points ago to the corresponding sliding window.

[0042] The medium temperature rise rate kT is an overall indicator of polishing energy dissipation. During normal polishing, mechanical work is converted into heat, and the temperature rise rate is stable. When abrasive particles accumulate and internal friction intensifies, the temperature rise rate rises abnormally. When cavitation occurs, the collapse of bubbles releases additional heat, and the temperature rise rate also deviates from the normal range.

[0043] When the predicted flow resistance change trend stabilizes, increase the sampling frequency. In practice, increase the sampling frequency until the sampling interval is halved. When predicting the relaxation of the flow resistance change trend, if the flow resistance characteristic value Rf is lower than the critical lower limit ratio of the initially calibrated characteristic threshold Rb, it is judged that there is a risk of excessive removal of material in the large-hole section, and the standard amplitude of the inlet pressure P1 at the large-hole end is reduced.

[0044] In practice, the initial calibrated feature threshold Rb ranges from 5 to 25 Pa·s / ml, the critical lower limit ratio is 80%, and the standard amplitude is 10%.

[0045] Before polishing begins, the abrasive flow medium is introduced using the current part to be processed with initial inlet pressure and initial ultrasonic power. After the flow stabilizes, the arithmetic mean of the flow resistance characteristic value Rf of 100 consecutive sampling points is taken as the initial calibrated characteristic threshold Rb.

[0046] Understandably, the characteristic threshold Rb and the critical lower limit ratio are used together to measure the risk of material removal in large-aperture sections when the predicted flow resistance change trend relaxes. In ultrasonic-assisted abrasive flow polishing of oxygen-free copper microchannels, the flow resistance characteristic value Rf is estimated to be on the order of 1~30 Pa·s / ml based on the typical range of inlet pressure and medium flow rate. Combining the throttling effect of the microchannel and the high viscosity characteristics of the abrasive flow medium, most normal operating conditions fall within the range of 5~25 Pa·s / ml. If the calibrated value significantly exceeds this range, the sensor zero point should be checked or the medium and channel specifications should be confirmed to be compatible. At the same time, if the ratio is set too high, false alarms will occur frequently, and if it is set too low, the aperture will be seriously out of tolerance when an alarm is triggered. The critical lower limit ratio is an engineering balance value between timely protection and avoiding false alarms.

[0047] Specifically, this invention achieves online identification of the polishing state inside the microchannel by real-time acquisition of inlet pressure, medium flow rate, and outlet temperature, calculation of flow resistance characteristic values ​​and their first-order rate of change and second-order acceleration, and combining this with the medium temperature rise rate. When the flow resistance rate of change exceeds a threshold, the flow state is classified into three categories—stabilization, deterioration, and relaxation—based on its combined trend with the flow resistance acceleration, and differentiated responses are adopted for each category, such as increased sampling, pressure reduction protection, or in-depth diagnostics. This method can promptly detect abnormal trends such as abrasive particle aggregation, debris accumulation, or cavitation erosion during the removal of drill marks and burrs from variable diameter steps, avoiding excessive material removal in large-diameter sections and out-of-tolerance diameter removal in small-diameter sections. While ensuring the uniformity of surface quality in each section of the variable-diameter microchannel, it effectively reduces the risk of workpiece scrap.

[0048] To predict the worsening trend of flow resistance, the electrical power input is read from the ultrasonic generator to obtain the real-time ultrasonic power Wu of the ultrasonic transducer. The real-time ultrasonic power Wu reflects the rate at which the ultrasonic system injects energy into the medium. Under normal polishing conditions, part of the real-time ultrasonic power Wu is converted into cavitation effect and acts on the wall surface, while the other part is absorbed by the medium and converted into internal heat. When the state of the medium changes, the energy distribution relationship will also change.

[0049] The temperature rise-flow resistance coupling coefficient λ is determined based on the medium temperature rise rate kT and the flow resistance change rate kR. The temperature rise-flow resistance coupling coefficient λ is determined based on the ratio of the medium temperature rise rate kT to the flow resistance change rate kR. Specifically, the temperature rise-flow resistance coupling coefficient λ reflects the additional temperature rise corresponding to a unit increase in flow resistance. It is used to distinguish whether the dominant mechanism of deterioration is increased internal friction or pure geometric blockage or cavitation damage when the flow resistance continues to increase by quantifying the proportional relationship between the additional temperature rise and the increase in flow resistance. As for the medium temperature rise rate kT, its value reflects the overall rate at which mechanical energy and ultrasonic energy dissipation are converted into heat during polishing. During normal polishing, energy is converted into medium temperature rise at a stable rate. When abrasive particles accumulate in the transition zone of the variable diameter, causing an increase in the local viscosity of the medium, the internal shear friction of the medium is significantly enhanced, the additional heat generated per unit time increases, and the medium temperature rise rate increases. As for the flow resistance change rate kR, its value reflects how fast the overall resistance of the channel to the fluid changes over time. When abrasive particle accumulation, debris buildup, or cavitation causes wall damage, the effective flow area of ​​the channel decreases or the flow resistance of the medium increases, and the flow resistance change rate kR increases. It is understandable that increased flow resistance accompanied by additional temperature rise indicates intensified friction within the medium, with abrasive particles accumulating in the variable diameter region leading to increased local viscosity; increased flow resistance but no significant additional temperature rise indicates that frictional heat generation is not the dominant factor, and that there is geometric blockage or cavitation damage.

[0050] The temperature rise energy ratio ξT is determined based on the outlet medium temperature T and the real-time ultrasonic power Wu. The temperature rise energy ratio ξT is determined based on the ratio of the temperature reference difference to the ultrasonic energy input. The temperature rise energy ratio ξT represents the temperature rise of the medium caused by a unit ultrasonic energy input, in K / J.

[0051] Wherein, the temperature reference difference is the difference between the outlet medium temperature T and the medium reference temperature, and the medium reference temperature is the inlet medium reference temperature calibrated before polishing begins; the ultrasonic energy input is the product of the real-time ultrasonic power Wu and the cumulative time, and the cumulative time is the cumulative time from the start of the current polishing stage to the current moment.

[0052] The energy ratio change trend kξ of the temperature rise energy ratio ξT is obtained. The energy ratio change trend kξ is determined based on the change in the temperature rise energy ratio ξT between sampling points and the sliding window. The energy ratio change trend kξ is determined based on the ratio of the difference between the temperature rise energy ratio ξT of the current sampling point and that of 5 sampling points ago to the corresponding sliding window.

[0053] An increase in the temperature rise energy ratio ξT indicates enhanced absorption of ultrasound by the medium, suggesting increased viscosity or abrasive particle aggregation. Violent fluctuations in the temperature rise energy ratio ξT suggest intermittent absorption and release of heat by cavitation bubble clusters.

[0054] Specifically, the temperature rise energy ratio ξT is used to measure the magnitude of temperature rise in the medium caused by a unit ultrasonic energy input. By monitoring the change in the efficiency of ultrasonic energy being absorbed by the medium and converted into heat, it helps to determine whether there are abnormal changes in the internal state of the medium. As for the temperature reference difference, when the viscosity of the medium increases due to the aggregation of abrasive particles, the absorption attenuation of the medium to ultrasound increases, and more ultrasonic energy is converted into internal friction heat rather than effective cavitation work, thus accelerating the accumulation rate of the temperature reference difference. When the cavitation bubble group grows and collapses intermittently, the absorption and scattering of ultrasound by the bubbles are unstable, and the accumulation of the temperature reference difference shows violent fluctuations. For ultrasonic energy input, under the same ultrasonic energy input, different medium states will lead to significant differences in temperature reference difference. Therefore, when the temperature rise energy ratio ξT continuously increases, it indicates that the medium's absorption efficiency of ultrasound is increasing, suggesting an increase in medium viscosity or abrasive particle aggregation. When the temperature rise energy ratio fluctuates drastically, it indicates that the absorption and release process of ultrasonic energy is unstable, suggesting the intermittent effect of cavitation bubble groups. By monitoring the absolute level and trend of the temperature rise energy ratio, quantitative evidence can be provided to distinguish between three types of deterioration mechanisms: internal friction-dominated, cavitation cavitation, and geometric blockage.

[0055] If the temperature rise flow resistance coupling coefficient λ is greater than the first coefficient threshold and the energy ratio change trend is greater than zero, the trend deterioration is judged to be internal friction-dominated deterioration; abrasive particles accumulate in the variable diameter transition zone, which leads to an increase in local viscosity of the medium, intensifies shear friction, and at the same time, the high viscosity medium enhances the absorption of ultrasound. If the temperature rise flow resistance coupling coefficient λ is less than the first coefficient threshold or the energy ratio change trend is less than zero, then the trend deterioration is distinguished as geometric blockage and cavitation cavitation.

[0056] It is understandable that a temperature rise-flow resistance coupling coefficient λ less than or equal to the second coefficient threshold indicates that the flow resistance increases but the additional temperature rise is not significant, and the absolute value of the energy ratio change trend is greater than the fluctuation threshold, indicating that the ultrasonic energy utilization rate is unstable.

[0057] Specifically, if the flow-temperature-resistance coupling coefficient λ is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is greater than the fluctuation threshold, the trend deterioration is judged to be cavitation cavitation-dominated deterioration. Cavitation occurs in the throttling zone at the variable diameter outlet. The growth and collapse of the cavitation bubble group causes intermittent absorption and scattering of ultrasonic waves, resulting in violent fluctuations in ultrasonic energy transfer. At the same time, the local high temperature of cavitation collapse is insufficient to significantly heat the overall medium, and the temperature rise flow resistance coupling coefficient λ remains low. Among them, if the temperature rise flow resistance coupling coefficient λ is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is less than or equal to the fluctuation threshold, the trend deterioration is judged to be geometric blockage-dominated deterioration. Drilling burrs and debris accumulate at the transition step, causing pure geometric blockage, while the properties of the medium itself and the ultrasonic energy transfer do not change significantly.

[0058] In practice, the first and second coefficient thresholds are determined based on the λ reference value calibrated under normal working conditions. Specifically, it is determined by using a standard workpiece and polishing it stably for more than 5 minutes under normal working conditions where there is no blockage or cavitation, and the average value of the temperature rise flow resistance coupling coefficient λ during this period. In practice, the benchmark value is between 0.08 and 0.25 K / Pa; the first coefficient threshold is 1.2 to 1.5 times the benchmark value, the second coefficient threshold is 0.8 to 1.0 times the benchmark value, and the fluctuation threshold is the fluctuation threshold of the energy ratio change trend. In practice, the fluctuation threshold ranges from 0.02 to 0.08, with the unit being K / (J·s).

[0059] Specifically, the baseline value is based on the first and second coefficient thresholds. Under normal polishing conditions, the flow resistance and temperature change slowly and gradually. Combining the typical values ​​of flow resistance and temperature, the absolute value range of their ratio is 0.05~1.0 K·s / (Pa·s·ml). Considering the unified unit conversion, under the conditions of ultrasonic-assisted abrasive flow polishing in oxygen-free copper microchannels, the baseline value for most normal conditions falls within the range of 0.08~0.25 K / Pa. 1.2 times the baseline value is taken as the lower boundary of the first coefficient threshold. If it exceeds the normal fluctuation range, random fluctuations will not be misjudged as abnormal. When λ exceeds 1.5 times the baseline value, the additional temperature rise is significant, and the increased friction in the medium is certain. Setting the threshold higher can reduce misjudgment but will lead to diagnostic delay and missing the optimal adjustment window. The lower limit of 0.8 times is to accommodate the normal fluctuation range. If it is below 0.8 times the baseline value, it has deviated significantly from the normal level.

[0060] The trend deteriorates into internal friction-dominated deterioration. Reduce the standard amplitude of the inlet pressure P1 at the large orifice end. The standard amplitude in practice is 15%. Reduce the flow velocity and shear rate at the diameter change. The trend deteriorates into cavitation cavitation-dominated deterioration. Reduce the ultrasonic power Wu to less than 50% of the preset percentage of the reference power to reduce the excitation energy for cavitation nucleation. The trend deteriorated into a geometric blockage-dominated deterioration, determining the degree of polishing impact on large and small hole segments within the part.

[0061] Specifically, when the flow resistance change trend is determined to be deteriorating, the ultrasonic power is introduced in combination with the temperature rise flow resistance coupling coefficient and temperature rise energy ratio and their changing trends. The deterioration mechanism is further divided into three categories: internal friction-dominated, cavitation cavitation-dominated, and geometric blockage-dominated. By identifying the significance of the additional temperature rise and the stability of ultrasonic energy transfer during the increase in flow resistance, it is possible to accurately distinguish the increase in medium viscosity caused by abrasive particle aggregation, the intermittent absorption and scattering of ultrasound by cavitation bubble groups, and the pure geometric accumulation of drilling burrs and debris. Differentiated measures such as pressure and speed reduction, reduction of ultrasonic power, or entry into two-stage decoupling evaluation are adopted for different mechanisms to avoid ineffective adjustment or reverse damage caused by misjudgment. This achieves accurate diagnosis and targeted intervention for abnormal polishing of variable diameter microchannels.

[0062] The trend deteriorates into a geometric blockage-dominated deterioration, and the long-term moving average Ts of the temperature obtained based on the outlet medium temperature T reflects the cumulative trend. In practice, a long-window moving average is performed on the outlet medium temperature T to obtain the temperature moving average Ts. The temperature moving average Ts is obtained by taking the arithmetic mean of the temperature values ​​of the current sampling point and the previous multiple consecutive sampling points. The window duration of the temperature sliding mean Ts covers the estimated transit time of the medium from the large orifice inlet to the outlet. In practice, if the transit time is about 2 seconds and the sampling frequency is 20Hz, then the window width is 40 sampling points.

[0063] It is understandable that the temperature sliding mean Ts filters out short-term fluctuations and retains the long-term trend of temperature changes. Changes in the friction state of the large-hole section will cause the temperature sliding mean Ts to shift.

[0064] The temperature fluctuation intensity ratio γ is determined based on the temperature sliding mean Ts and the temperature fluctuation intensity. The temperature fluctuation intensity ratio γ is determined based on the ratio of the temperature fluctuation intensity to the temperature sliding mean Ts. In practice, the difference between the current sampling point and the temperature sliding mean Ts reflects the instantaneous fluctuation. The root mean square value of the difference within several short sliding windows is calculated to obtain the intensity of the temperature fluctuation. The width of the short window is smaller than the width of the long window. In practice, if 20 sampling points are taken, it corresponds to 1 second.

[0065] It is understandable that when the temperature fluctuation intensity is larger than γ, the energy proportion of rapid fluctuations in the temperature signal is high, and the throttling effect of the small orifice section is the main driving factor of the current temperature change; when the temperature fluctuation intensity is smaller than γ, the temperature signal is mainly characterized by slow accumulation, and rapid fluctuations are not significant, and the frictional heat of the large orifice section is the main driving factor of the current temperature change.

[0066] The contribution ratio of flow resistance in the small orifice section is determined by piecewise linear mapping based on the temperature fluctuation intensity ratio γ. If the temperature fluctuation intensity ratio γ is greater than or equal to the first intensity ratio threshold, the flow resistance contribution ratio is set to the maximum value of the flow resistance contribution ratio, with the small hole contributing the most. If the temperature fluctuation intensity ratio γ is less than or equal to the second intensity ratio threshold, then the flow resistance contribution ratio is set to the minimum flow resistance contribution ratio, with large holes contributing the most. If the temperature fluctuation intensity ratio γ is less than the first intensity ratio threshold and greater than the second intensity ratio threshold, then the flow resistance contribution ratio is set to be a linear interpolation between the minimum and maximum flow resistance contribution ratios according to the ratio of γ.

[0067] In practice, the preferred range for the first strength ratio threshold is 0.1 to 0.12, and the preferred range for the second strength ratio threshold is 0.03 to 0.05. The minimum and maximum values ​​of the flow resistance contribution ratio are empirical ranges of the contribution ratio. In practice, the minimum flow resistance contribution ratio is 0.1, and the maximum flow resistance contribution ratio is 0.9.

[0068] Understandably, during normal polishing, the temperature fluctuation intensity ratio γ is typically between 0.03 and 0.08. When the temperature fluctuation intensity ratio exceeds 0.1, the proportion of rapid fluctuation energy in the temperature signal has significantly deviated from the normal range, and the throttling effect of the small orifice segment becomes the main driving factor for temperature change. The preferred range of the first intensity ratio threshold can leave a safe distance between normal fluctuation and abnormality to avoid misjudgment. When the temperature fluctuation intensity ratio is lower than the preferred range of the second intensity ratio threshold, the proportion of rapid fluctuation energy is extremely low, and temperature change is mainly slow accumulation, indicating that the frictional heat of the large orifice segment is the main driving factor. The lower limit of the second intensity ratio threshold is set at 0.03 to prevent signal noise from being misjudged as effective fluctuation, and the upper limit is set at 0.05 to retain the transition range and make the segmented mapping continuous and stable. Both the small orifice segment and the large orifice segment contribute to the total flow resistance, and there is no extreme case where the contribution of one side is zero. The example value of the minimum flow resistance contribution ratio ensures that the large orifice segment is always included in the evaluation, and the example value of the maximum flow resistance contribution ratio ensures that the contribution of the small orifice segment is not completely equal to the total flow resistance.

[0069] The flow resistance component contributed by the orifice section is determined based on the proportion of flow resistance contribution of the orifice section combined with the flow resistance characteristic value Rf. The flow resistance component contributed by the orifice section is determined based on the product of the flow resistance characteristic value Rf and the flow resistance contribution proportion. The orifice diameter variation trend index is determined based on the flow resistance component contributed by the orifice section. The orifice diameter variation trend index is determined based on the ratio of the rate of change of the flow resistance component contributed by the orifice section to the flow resistance component contributed by the orifice section.

[0070] It is understandable that the flow resistance of the small orifice section is inversely proportional to the square of the orifice diameter. A small orifice diameter change trend index >0 indicates that the flow resistance of the small orifice section is increasing and the orifice diameter is decreasing, possibly due to debris embedding or abrasive accumulation. A small orifice diameter change trend index less than zero indicates that the flow resistance of the small orifice section is decreasing and the orifice diameter is increasing, indicating that material is being removed.

[0071] If the orifice diameter change trend index is less than the negative safety threshold or the flow resistance component contributed by the orifice is less than the flow resistance critical value, then the orifice is judged to have a risk of exceeding the tolerance limit; otherwise, the orifice does not have a threat of exceeding the orifice tolerance, and the orifice diameter status of the orifice is judged to be safe.

[0072] The safety threshold is the orifice expansion rate safety threshold, and the flow resistance critical value is the flow resistance critical value corresponding to the maximum allowable orifice diameter. In practice, the preferred range for the safety threshold is 0.008~0.015 s. -1 The preferred range for the critical flow resistance value is 2~8 Pa·s / ml.

[0073] Understandably, the orifice diameter variation trend index represents the relative rate of change of flow resistance in the orifice section. During normal polishing, material removal is slow, and when it exceeds 0.01 s... -1At this point, the rate of orifice diameter expansion has substantially deviated from the normal rhythm; taking 0.008~0.015 can effectively distinguish between normal polishing and abnormally rapid removal; the throttling resistance of the orifice segment is inversely proportional to the square of the orifice diameter. For typical orifice diameters of 0.5~2mm in microchannels, under normal operating conditions, the measured orifice segment flow resistance component of a standard workpiece with an orifice diameter at the upper limit of the tolerance falls within the range of 2~8 Pa·s / ml; the larger the orifice diameter, the lower the value is taken, and the smaller the orifice diameter, the upper the value is taken, covering the design tolerance requirements of most microchannel heat exchangers.

[0074] The power fluctuation intensity σW of the real-time ultrasonic power Wu within the sliding window is calculated. The power fluctuation intensity σW is determined based on the ratio of the standard deviation of the real-time ultrasonic power Wu within the sliding window to the mean of the real-time ultrasonic power Wu within the sliding window. The width of the sliding window is 50 sampling points. When the wall surface of the large hole is rough, the sound wave scattering is chaotic, the transducer load impedance is unstable, the real-time ultrasonic power Wu fluctuates greatly, and the power fluctuation intensity σW is large. When the wall surface gradually becomes smooth, the sound wave reflection is regular, the load impedance is stable, the real-time ultrasonic power Wu fluctuation decreases, and the power fluctuation intensity σW approaches zero.

[0075] The roughness improvement trend kb of the large hole section is calculated based on the power fluctuation intensity σW. The roughness improvement trend kb of the large hole section is determined by the ratio of the difference between the power fluctuation intensity of the current sampling point and that of 10 sampling points to that of 10 sampling windows. A roughness improvement trend in the large-diameter section with kb greater than zero indicates that the power fluctuation intensity σW is decreasing and the roughness of the large-diameter section is improving; a roughness improvement trend in the large-diameter section with kb less than zero indicates that the roughness improvement has stagnated or regressed.

[0076] If the roughness improvement trend kb of the large hole section is greater than or equal to the target polishing efficiency, then the polishing of the large hole section is considered effective; if the roughness improvement trend kb of the large hole section is less than the target polishing efficiency, then the polishing of the large hole section is considered stagnant.

[0077] During implementation, when polishing in the large hole section stalls, the ultrasonic power Wu is increased based on the ratio of the roughness improvement trend kb in the large hole section to the target polishing efficiency; when there is a risk of exceeding the tolerance limit in the small hole section, the inlet pressure P1 at the large hole end is reduced based on the absolute value of the ratio of the small hole diameter change trend index to the safety threshold.

[0078] The target polishing efficiency is the target value of the polishing efficiency for the large-hole section. During the process development phase, it is determined by the steady-state positive value of the roughness improvement trend (kb) of the large-hole section under normal polishing conditions, calibrated using standard workpieces. In practice, the preferred range for the target polishing efficiency is 0.001~0.002s. -1 .

[0079] It is understandable that the trend of roughness improvement in the large-diameter section reflects the relative rate of change of power fluctuation intensity. During normal polishing, the wall surface of the large-diameter section gradually becomes smooth, and the power fluctuation intensity decreases slowly, falling below 0.001 s. -1 This indicates that improvement is nearing stagnation, above 0.002 s. -1 This usually only occurs during the rapid improvement phase in the initial stages of polishing.

[0080] Specifically, after determining that the deterioration is dominated by geometric blockage, this invention constructs a temperature fluctuation intensity ratio by using a long-window moving average and a short-window root-mean-square fluctuation of temperature. A piecewise linear mapping is used to decouple the total flow resistance into the contributions of the large-diameter and small-diameter sections, thereby calculating the trend index of the small-diameter section's diameter change. Simultaneously, the sliding window fluctuation intensity of ultrasonic power is used to assess the roughness improvement trend of the large-diameter section, achieving independent judgment of the polishing process of the large-diameter section and the diameter status of the small-diameter section. This method only uses existing temperature and ultrasonic power signals, without the need for additional sensors, to identify polishing stagnation in the large-diameter section and the risk of diameter deviation in the small-diameter section. It quantitatively adjusts the ultrasonic power based on the deviation from the target polishing efficiency and the inlet pressure based on the deviation from the safety threshold, achieving differentiated and precise control of the large-diameter and small-diameter sections, avoiding insufficient efficiency or diameter deviation caused by blind adjustment.

[0081] The threshold deviation index is calculated by obtaining the orifice diameter change trend index and the orifice diameter expansion rate safety threshold. The threshold deviation index is determined based on the ratio of the absolute value of the orifice diameter change trend index to the orifice diameter expansion rate safety threshold. When the threshold deviation index is less than the second index threshold, it is judged that the threshold deviation index is too small and too sensitive to small fluctuations. The threshold of the change rate of flow resistance kR is increased. The adjusted change threshold = change threshold × (1 + β), where β is the increase ratio. If the threshold deviation index is greater than or equal to the first index threshold, it is judged that the threshold deviation index is too large and the degree of abnormality is serious. The threshold of change of flow resistance change rate kR is reduced. The adjusted threshold of change = threshold of change × (1-β), where β is the reduction ratio. In practice, the threshold values ​​of the second and first indicators are the tolerance range for threshold deviation, and β is set to 0.05~0.1.

[0082] Understandably, the threshold deviation index is the ratio of the orifice diameter change trend index to the orifice diameter expansion rate safety threshold. In practice, the second index threshold is set to 0.3, and the first index threshold is set to 0.8. When the threshold deviation index is greater than or equal to the first index threshold, the orifice diameter change rate is close to 80% of the safety boundary, and the anomaly has developed to a relatively serious level. This indicates that the threshold is too large, causing the anomaly to be detected too late, and the threshold needs to be reduced to improve detection sensitivity. When the threshold deviation index is less than the second index threshold, the orifice diameter change rate is less than 30% of the safety threshold when the anomaly is triggered. This indicates that the threshold is too small and is too sensitive to small normal fluctuations, resulting in false triggering. The threshold needs to be increased to reduce the false alarm rate. β is the single adjustment ratio of the threshold, and 0.05~0.1 is the balance between adjustment speed and stability.

[0083] Specifically, this invention constructs a threshold deviation index by calculating the ratio of the orifice diameter change trend index to the safety threshold, and compares it with the threshold deviation tolerance range to determine the sensitivity of the current flow resistance change threshold. When the deviation index is too small, it indicates that the threshold is too small and too sensitive to normal fluctuations. The threshold is increased to reduce false triggering. When the deviation index is too large, it indicates that the threshold is too large and anomalies are not captured in time. The threshold is decreased to improve detection sensitivity. The negative feedback adjustment mechanism makes the flow resistance change threshold continuously approach the optimal range during the processing, taking into account both the timeliness of anomaly detection and anti-interference ability.

[0084] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A polishing method for precision component machining, characterized in that, include: Based on the inlet pressure at the large orifice end and the real-time flow rate of the medium, the characteristic values ​​of flow resistance, as well as the rate of change of flow resistance and the acceleration of flow resistance are extracted. The flow state of the medium is determined based on the rate of change of flow resistance and the trend of flow resistance change is predicted based on the acceleration of flow resistance. In response to the trend of flow resistance change, the degree of flow resistance reduction is determined based on the characteristic value of flow resistance, or the temperature rise flow resistance coupling coefficient and temperature rise energy ratio are determined; The temperature rise flow resistance coupling coefficient is determined based on the obtained medium temperature rise rate combined with the flow resistance change rate, and the temperature rise energy ratio is determined based on the outlet medium temperature combined with the real-time ultrasonic power. Based on the energy ratio change trend of the temperature rise energy ratio and combined with the temperature rise flow resistance coupling coefficient, the trend deterioration type is determined and the trend deterioration is distinguished into geometric blockage and cavitation cavitation. In response to the deterioration trend, adjust the inlet pressure and ultrasonic power at the large orifice end, or obtain the long-term sliding average of the temperature based on the medium temperature at the outlet end, and determine the temperature fluctuation intensity ratio by combining the temperature fluctuation intensity to piecewise linearly map the flow resistance contribution ratio of the small orifice section. The flow resistance contribution of the small orifice section is determined by combining the proportion of flow resistance contribution of the small orifice section with the flow resistance characteristic value, and the flow resistance component is combined with the rate of change of the flow resistance component to determine the trend index of the orifice diameter change of the small orifice section, and the polishing influence of the small orifice section of the component is determined to adjust the inlet pressure of the large orifice end. The trend of roughness improvement in large-hole sections is determined based on the power fluctuation intensity of ultrasonic power, so as to determine the degree of polishing influence of large-hole sections of components and adjust ultrasonic power accordingly. The threshold deviation index is calculated based on the orifice diameter change trend index and the orifice diameter expansion rate safety threshold to adjust the change threshold of the flow resistance change rate.

2. The polishing method for precision component machining according to claim 1, characterized in that, The process of determining the flow state of a medium includes: If the absolute value of the rate of change of flow resistance is less than or equal to the change threshold, the medium flow state is judged to be normal. If the absolute value of the rate of change of flow resistance is greater than the threshold value, it is determined that the change in the medium flow state is out of range, and the trend of flow resistance change is predicted by combining the flow resistance acceleration.

3. The polishing method for precision component machining according to claim 2, characterized in that, The process of predicting the trend of flow resistance changes includes: If the rate of change of flow resistance is greater than zero and the flow resistance acceleration is less than the negative acceleration threshold, then the predicted flow resistance change trend tends to stabilize, and the sampling frequency should be increased. If the rate of change of flow resistance is greater than zero and the flow resistance acceleration is greater than or equal to a negative acceleration threshold, the flow resistance change trend is predicted to worsen, indicating a risk of blockage or cavitation. When the rate of change of flow resistance is less than zero, the predicted trend of flow resistance change is relaxed, the channel resistance decreases and tends to be unobstructed, and the flow resistance characteristic value is used to determine whether the flow resistance decrease is excessive. If the flow resistance characteristic value is lower than the critical lower limit of the initially calibrated characteristic threshold, it is determined that there is a risk of excessive removal of material in the large-pore section, and the standard amplitude of the inlet pressure at the large-pore end is reduced.

4. The polishing method for precision component machining according to claim 3, characterized in that, The process of determining the type of trend deterioration includes: If the temperature rise flow resistance coupling coefficient is greater than the first coefficient threshold and the energy ratio change trend is greater than zero, the trend deterioration is judged to be internal friction-dominated deterioration. If the temperature rise flow resistance coupling coefficient is less than the first coefficient threshold or the energy ratio change trend is less than zero, then the trend deterioration is distinguished as geometric blockage and cavitation cavitation.

5. The polishing method for precision component machining according to claim 4, characterized in that, The process of distinguishing a deteriorating trend includes: If the temperature rise flow resistance coupling coefficient is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is greater than the fluctuation threshold, the trend deterioration is judged to be cavitation cavitation-dominated deterioration. If the temperature rise flow resistance coupling coefficient is less than or equal to the second coefficient threshold and the absolute value of the energy ratio change trend is less than or equal to the fluctuation threshold, the trend deterioration is judged to be geometric blockage-dominated deterioration.

6. The polishing method for precision component machining according to claim 5, characterized in that, The trend deteriorates into a deterioration dominated by internal friction, reducing the standard amplitude of the inlet pressure at the large orifice end and decreasing the flow velocity and shear rate at the component diameter change point; The trend worsens to cavitation cavitation-dominated deterioration, and the ultrasonic power is reduced by a preset percentage based on the reference power. The trend deteriorated into a geometric blockage-dominated deterioration, determining the degree of polishing impact on large and small hole segments within the part.

7. The polishing method for precision component machining according to claim 6, characterized in that, The temperature moving average is obtained by taking the arithmetic mean of the temperature values ​​of the current sampling point and several consecutive sampling points before it, and the temperature fluctuation intensity is obtained based on the root mean square value of the difference between several sampling points and the temperature moving average. If the temperature fluctuation intensity ratio is greater than or equal to the first intensity ratio threshold, it is determined that the flow resistance change is mainly contributed by the orifice, and the flow resistance contribution ratio is the maximum value of the flow resistance contribution ratio. If the temperature fluctuation intensity ratio is less than or equal to the second intensity ratio threshold, it is determined that the flow resistance change is mainly contributed by the large orifice, and the flow resistance contribution ratio is the minimum value of the flow resistance contribution ratio. If the temperature fluctuation intensity ratio is less than the first intensity ratio threshold and greater than the second intensity ratio threshold, then the flow resistance contribution ratio is a linear interpolation between the minimum and maximum flow resistance contribution ratios according to the ratio of the temperature fluctuation intensity ratio.

8. The polishing method for precision component machining according to claim 7, characterized in that, The process of adjusting the inlet pressure at the large orifice end includes: If the orifice diameter change trend index of the small orifice section is less than the negative safety threshold or the flow resistance component contributed by the small orifice section is less than the critical flow resistance value, it is judged that the small orifice section has a risk of exceeding the upper limit of tolerance. The inlet pressure of the large orifice end is reduced according to the absolute value of the ratio of the orifice diameter change trend index of the small orifice section to the safety threshold.

9. The polishing method for precision component machining according to claim 8, characterized in that, The power fluctuation intensity is the ratio of the standard deviation to the mean of the real-time ultrasonic power. If the roughness improvement trend of the large hole section is greater than or equal to the target polishing efficiency, then the polishing of the large hole section is considered effective. If the improvement trend of roughness in the large hole section is less than the target polishing efficiency, it is determined that the polishing of the large hole section has stalled, and the ultrasonic power is increased according to the ratio of the improvement trend of roughness in the large hole section to the target polishing efficiency.

10. The polishing method for precision component machining according to claim 9, characterized in that, The threshold deviation index is the ratio of the absolute value of the trend index of the aperture change in the small aperture segment to the safe threshold of the aperture expansion rate. When the threshold deviation index is less than the second index threshold, it is determined that the threshold deviation index is too small, and the threshold for the change in flow resistance rate is increased. If the threshold deviation index is greater than or equal to the first index threshold, it is determined that the threshold deviation index is too large, and the threshold for the change rate of flow resistance is reduced.

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