Method for realizing repeated clamping of circumferential parts for precision boring

Abstract

This invention relates to the field of workpiece drilling technology, specifically to a method for precision boring of circumferential parts with repeated clamping. This method determines the improvement index of each part at each station for each machining index sequence by analyzing the changes in the machining index sequence of each part at each station and its difference from reference values. It then selects qualified index sequences to determine the machining effectiveness index of each part at each station. Based on the changes in the machining effectiveness index, a machining quality stability index is determined, leading to a corrected machining effectiveness index for each station. The overall impact degree is determined based on the similarity between the same machining index sequences at different stations. The corrected impact degree for each station is obtained based on the similarity of the machining index sequences. This results in the machining quality index for each station. Adjustments to the precision boring process based on the machining quality index improve the accuracy of process adjustments for precision boring of circumferential parts with repeated clamping.

Description

Technical Field

[0001] This invention relates to the field of workpiece drilling technology, and more specifically to a precision boring method for repeatedly clamping circumferential parts. Background Technology

[0002] Boring is a cutting process that uses a boring tool on a boring machine, milling machine, or machining center to enlarge the diameter, modify the shape, and improve the accuracy of existing holes (cast holes, forged holes, or pre-drilled holes) in a workpiece. It is primarily used for machining high-precision holes, hole systems, and hole end faces, and is widely used in the machining of complex parts such as housings, frames, and bearing seats. Fine boring is the finishing process in boring, and its core purpose is to achieve high-precision dimensional tolerances, shape tolerances, and surface roughness requirements for the hole features of the workpiece through small-mass cutting. It is often used for machining the internal holes of key parts such as automotive engine cylinder blocks, bearing seats, and hydraulic valve blocks.

[0003] In the precision boring process of repeatedly clamping circular parts, existing methods are difficult to objectively and comprehensively evaluate the actual machining quality and stability of each station under multi-station, continuous machining conditions. Consequently, they cannot accurately distinguish between the machining quality fluctuations caused by the insufficient machining capacity of a single station and the interference of multi-station linkage, resulting in inaccurate process adjustments. Summary of the Invention

[0004] To address the technical problem of inaccurate process adjustment during the precision boring of repeatedly clamped circumferential parts, the present invention aims to provide a method for precision boring of repeatedly clamped circumferential parts. The specific technical solution adopted is as follows:

[0005] This invention provides a precision boring method for repeatedly clamping circular parts, the method comprising:

[0006] Obtain a series of machining indexes for each part at each workstation during precision boring, as well as a reference value for each machining index series;

[0007] Based on the changes in the processing index sequence of each part at each workstation and the difference from the reference value, the improvement index of each part at each workstation in each processing index sequence is determined, and qualified index sequences are screened; based on the improvement index and the number of qualified index sequences, the processing effectiveness index of each part at each workstation is determined.

[0008] Based on the changes in the processing effectiveness index of each station during multiple consecutive precision boring operations of parts, a processing quality stability index for each station is determined; based on the processing effectiveness index and the processing quality stability index, a corrected processing effectiveness index for each station is determined.

[0009] Based on the similarity between the same processing index sequences of different workstations, the overall impact degree of each workstation is determined; based on the similarity of the processing index sequences of parts between workstations, the overall impact degree of each workstation is corrected to obtain the corrected impact degree of each workstation.

[0010] The processing quality index for each workstation is obtained based on the modified processing effectiveness index and the degree of impact of the modification, and the precision boring process is adjusted according to the processing quality index.

[0011] Furthermore, the method for obtaining the improvement index includes:

[0012] For any part at any workstation and any processing index sequence, the delay improvement index of the processing index sequence is determined based on the slope of the fitted line of the elements in the processing index sequence.

[0013] The standard scoring index of any processing indicator sequence is determined based on the difference between the last element value in any processing indicator sequence and the reference value of any processing indicator sequence.

[0014] The improvement index of any processing index sequence is obtained based on the delay improvement index and the standard scoring index.

[0015] Furthermore, the method for obtaining the processing effectiveness index includes:

[0016] For any part at any workstation, determine the pass rate index of the part based on the proportion of the pass rate index sequence of the part in all processing index sequences.

[0017] Based on the overall situation of the improvement index of all processing index sequences of any given part, determine the comprehensive improvement index of any given part;

[0018] The processing effectiveness index of any given part is determined based on the qualified percentage index and the comprehensive improvement index of that part.

[0019] Furthermore, the method for obtaining the processing quality stability index includes:

[0020] For any given workstation, based on the change in the processing effectiveness index of the parts at that workstation, determine the processing effectiveness change index of each part at that workstation; and screen out stable expression parts based on the processing effectiveness change index.

[0021] Based on the change index of the processing performance of the stable expression parts at any given workstation, and the proportion of the stable expression parts at any given workstation, the processing quality stability index of any given workstation is obtained.

[0022] Furthermore, the method for obtaining the overall degree of impact includes:

[0023] For any given workstation, obtain the surrounding workstations of that workstation and the positional relationship between that workstation and each of the surrounding workstations;

[0024] Based on the difference in the processing index sequence of any one workstation and each of its surrounding workstations, the degree of influence of any one workstation and each of its surrounding workstations on each processing index sequence is obtained.

[0025] By utilizing the positional relationship between any given workstation and each of its surrounding workstations, the degree of influence of any given workstation and each of its surrounding workstations is weighted and fused to obtain the degree of influence of each processing indicator sequence of any given workstation.

[0026] The overall impact level of any given workstation is obtained by considering the degree of influence of all processing indicator sequences at that workstation.

[0027] Furthermore, the method for obtaining the degree of impact of the correction includes:

[0028] The processing index sequence includes a surface roughness sequence, which is composed of the surface roughness of any part collected during the precision boring process of repeated clamping of a circumferential part.

[0029] Based on the similarity of surface roughness between parts at different workstations, the workstations are divided into several wear clusters;

[0030] For any workstation in any wear cluster, the influence correction coefficient of the workstation is obtained based on the similarity of the processing index sequence of the workstation to other workstations in the wear cluster.

[0031] The overall impact degree of any workstation is corrected by using the aforementioned impact correction coefficient to obtain the corrected impact degree of any workstation.

[0032] Furthermore, the method for obtaining the modified processing effectiveness index includes:

[0033] Obtain the average value of the processing effectiveness index of all parts at any workstation, and multiply the average value by the processing quality stability index of the workstation to denot the corrected processing effectiveness index of the workstation.

[0034] Furthermore, the method for obtaining the processing quality index includes:

[0035] For any workstation, the normalized result of the product of the reciprocal of the degree of influence of the correction on the workstation and the correction processing effectiveness index is denoted as the processing quality index of the workstation.

[0036] Furthermore, the specific method for obtaining the improvement index of any processing indicator sequence based on the delay improvement index and the standard scoring index includes:

[0037] The average of the delay improvement index and the standard score index is denoted as the improvement index of any processing index sequence.

[0038] Furthermore, the method for obtaining the qualified indicator sequence includes:

[0039] For any part at any workstation and any processing index sequence, if the standard scoring index of the processing index sequence is greater than the preset pass threshold, the processing index sequence is recorded as the pass index sequence of the part.

[0040] The present invention has the following beneficial effects:

[0041] To address the issue of inaccurate process adjustments in the precision boring of repeatedly clamped circular parts, this invention determines the machining effectiveness index for each part at each station by improving the index and the number of qualified indicator sequences, thus evaluating the overall improvement effect of key machining indicators. By using the machining effectiveness index and the machining quality stability index, a corrected machining effectiveness index for each station is determined, enabling the assessment of machining quality stability over time and improving the reliability of the machining effectiveness evaluation results. Based on the similarity of machining indicator sequences between stations, the overall impact degree of each station is corrected to obtain the corrected impact degree, assessing the degree of external interference affecting each station and thus determining the uncertainty in the machining quality evaluation of each station. Therefore, by correcting the machining effectiveness index and the impact degree, the machining quality index for each station is obtained. Adjustments to the precision boring process based on this machining quality index improve the accuracy of process adjustments for the precision boring of repeatedly clamped circular parts. Attached Figure Description

[0042] To more clearly illustrate the technical solutions and advantages 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 these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating the steps of a precision boring method for repeatedly clamping circular parts, as provided in an embodiment of the present invention. Detailed Implementation

[0044] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the precision boring method for repeatedly clamping circumferential parts proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0046] The specific solution of the precision boring method for repeatedly clamping circular parts provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0047] Please see Figure 1 This illustrates a flowchart of a precision boring method for repeatedly clamping circular parts, provided by an embodiment of the present invention. Figure 1 As shown, the method specifically includes the following steps:

[0048] Step S1: Obtain a series of machining indexes for each part at each workstation during precision boring, as well as a reference value for each machining index sequence.

[0049] It should be noted that the main purpose of this embodiment is to analyze several machining indicators of each part at each station during the precision boring process of repeatedly clamping and machining circumferential parts, to determine the machining quality of the parts at each station, and to adjust the machining parameters of stations with poor machining quality. Therefore, the sequence of several machining indicators for each part at each station during precision boring is first obtained.

[0050] Specifically, the precision boring process is divided into several discrete detection nodes (e.g., layered by feed depth). When the machining program reaches a detection node, the spindle pauses cutting and maintains its current speed, the tool temporarily retracts, and while the workpiece remains in its current clamping state and has not completely left the machine coordinate system, the online measurement device is triggered. The specific measurement process includes:

[0051] The coaxiality of the parts is obtained by using a high-precision laser interferometer integrated in the machine tool. According to the order of the acquisition time of the coaxiality, the coaxiality of all detection nodes of each part is arranged to obtain the coaxiality sequence of each part at each station.

[0052] The roundness of the parts is obtained using a roundness meter. The roundness of all detection nodes of each part is arranged according to the chronological order of the roundness acquisition time to obtain the roundness sequence of each part at each station.

[0053] The surface roughness of the parts is obtained using a surface roughness meter. The surface roughness of all detection nodes of each part is arranged according to the chronological order of the acquisition time to obtain the surface roughness sequence of each part at each station.

[0054] Based on the size of the part's hole diameter, an electronic inside micrometer or a coordinate measuring machine is used to obtain the measured hole diameter at each inspection node. The absolute value of the difference between the measured hole diameter and the designed hole diameter is recorded as the hole diameter error value of the part. According to the order of the acquisition time of the hole diameter error values, the hole diameter error values ​​of all inspection nodes of each part are arranged to obtain the hole diameter error sequence of each part at each station.

[0055] For any given part, the coaxiality sequence, roundness sequence, surface roughness sequence, and hole diameter error sequence of that part are used as the machining index sequence of that part.

[0056] Obtain the process standard value corresponding to each processing index sequence of the part, and record it as the reference value of each processing index sequence of the part.

[0057] Step S2: Based on the changes in the processing index sequence of each part at each workstation and the difference from the reference value, determine the improvement index of each part at each workstation in each processing index sequence, and screen qualified index sequences; based on the improvement index and the number of qualified index sequences, determine the processing effectiveness index of each part at each workstation.

[0058] It should be noted that in the scenario of repeated clamping and precision boring of circumferential parts, due to the combined effects of clamping errors, tool wear and working condition fluctuations, the machining indicators of the parts at each station show different trends in multiple machining processes. Therefore, it is necessary to analyze the changing trends of several machining indicator sequences for each station and each part with the number of machining cycles and the degree of deviation of the final result from the reference value, so as to construct an improvement index that can simultaneously reflect the improvement speed and the final achievement status, and then judge the machining effectiveness that can comprehensively characterize the actual machining effect of the parts in repeated clamping and precision boring.

[0059] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the improvement index includes:

[0060] For any part at any workstation and any processing index sequence, the delay improvement index of the processing index sequence is determined based on the slope of the fitted line of the elements in the processing index sequence.

[0061] Specifically, the methods for obtaining the delay improvement index include:

[0062] The inverse proportional normalization result of the absolute value of the slope of the straight line obtained by fitting any processing index sequence using the least squares method is denoted as the delay improvement index of the processing index sequence; wherein, the normalization method is the maximum-minimum normalization function; wherein, the inverse proportional normalization processing adopts... To present it using a model, Let be the absolute value of the slope of the fitted line. The minimum normalization function is used; the process of fitting a straight line using the least squares method is a well-known technique, and the specific method will not be introduced here.

[0063] It should be noted that during repeated precision boring, each processing index is a deviation-type index. Ideally, it should quickly approach the reference value and remain stable after a small number of processing cycles. When the absolute value of the slope of the least squares fitted line is small, it indicates that the processing index changes gradually with the number of processing cycles, has been basically improved, and has entered the stable control range, demonstrating that the improvement is completed quickly and the process is highly stable.

[0064] Furthermore, based on the difference between the last element value in any processing indicator sequence and the reference value of any processing indicator sequence, a standard scoring index for any processing indicator sequence is determined.

[0065] Specifically, the method for obtaining the standard scoring index includes: for any part at any workstation and any processing index sequence, since the last element of the processing index sequence represents the final effect of the part in that processing index sequence, the absolute value of the difference between the last element of the processing index sequence and the reference value of the processing index sequence is obtained. The result of inversely normalizing the absolute value of the difference is recorded as the standard scoring index of the processing index sequence; wherein, the inverse normalization process adopts... To present it using a model, The absolute value of the difference is obtained by subtracting the reference value of the processing index sequence from the last element of the processing index sequence.

[0066] Furthermore, based on the delay improvement index and the standard scoring index, the improvement index of any processing index sequence is obtained.

[0067] Specifically, the methods for obtaining the improvement index include:

[0068] It should be noted that the delayed improvement index reflects how quickly the processing index converges to the reference value, while the standard scoring index reflects how close the final processing result is to the reference value. When the mean of the two is larger, it means that the processing index can not only be effectively improved in fewer processing times, but also that its final test result deviates less from the reference value and has a higher quality level. The corresponding processing index sequence has a better improvement effect in the whole processing process.

[0069] The average of the delay improvement index and the standard score index is denoted as the improvement index of any processing index sequence.

[0070] It should be noted that the larger the improvement index of the processing index sequence, the better the improvement speed and the better the improvement result of the processing index corresponding to that processing index sequence during the processing of the part.

[0071] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the qualified indicator sequence includes:

[0072] For any part at any workstation and any processing index sequence, if the standard scoring index of the processing index sequence is greater than the preset pass threshold, the processing index sequence is recorded as the pass index sequence of the part; wherein the preset pass threshold is 0.8, and this embodiment is described using this as an example.

[0073] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the processing effectiveness index includes:

[0074] For any part at any workstation, the pass rate index of the part is determined based on the proportion of the pass rate index sequence of the part in all processing index sequences.

[0075] Specifically, the methods for obtaining the pass / fail ratio index include:

[0076] The ratio of the number of qualified indicator sequences for any given part to the total number of all processing indicator sequences is denoted as the qualified percentage index of that given part.

[0077] Furthermore, based on the overall situation of the improvement index of all processing index sequences of any given part, the comprehensive improvement index of any given part is determined;

[0078] The processing effectiveness index of any given part is determined based on the qualified percentage index and the comprehensive improvement index of that part.

[0079] Specifically, the methods for obtaining the processing effectiveness index include:

[0080] For each processing index sequence of any given part, a preset feature weight is assigned. The improvement index of all processing index sequences of any given part is weighted and summed using the preset feature weights, and this summation is recorded as the comprehensive improvement index of the given part. It should be noted that the hole diameter is the most critical and direct functional indicator in precision boring, and its deviation directly determines whether the part is assembled correctly; therefore, it is given the highest weight. Roundness error has a significant impact on fit uniformity and service life, and is a key form and position accuracy indicator, with the next highest weight. Coaxiality error mainly reflects the consistency between the clamping and machining axes, and has a significant impact on high-precision assembly, but its allowable range is usually slightly larger than the size, so its weight is relatively low. Surface roughness affects friction performance and surface quality more, and its impact on functionality is slightly smaller than the aforementioned indicators in the precision boring process; therefore, it is given an even lower weight. As an example, in this embodiment, the preset feature weight for the hole diameter error sequence is 0.4, the preset feature weight for the roundness sequence is 0.25, the preset feature weight for the coaxiality sequence is 0.2, and the preset feature weight for the surface roughness sequence is 0.15.

[0081] The linearly normalized result of the product of the qualified percentage index and the comprehensive improvement index of any given part is denoted as the processing effectiveness index of any given part; wherein, the linear normalization method is the maximum-minimum normalization function.

[0082] It should be noted that the higher the machining effectiveness index of a part, the more significant the overall improvement in key machining indicators is during the repeated clamping and precision boring process at its station. This indicates that the part has achieved relatively ideal and reliable machining quality under the current clamping conditions, tool condition and process parameters, and its machining process stability and result consistency are at a relatively good level.

[0083] Step S3: Determine the machining quality stability index of each station based on the changes in the machining effectiveness index during multiple consecutive precision boring operations of the parts; determine the corrected machining effectiveness index of each station based on the machining effectiveness index and the machining quality stability index.

[0084] It should be noted that the machining effectiveness index of a part only reflects the overall machining effect of a single part in a single precision boring operation, and it is difficult to indicate whether the machining behavior of the workstation is stable over time. In the scenario of repeated clamping precision boring, factors such as tool wear, changes in fixture condition, and machine tool thermal characteristics often have cumulative and temporal effects. Therefore, further historical stability analysis based on the changes in the machining effectiveness index of the same workstation during multiple consecutive precision boring operations of parts makes the evaluation of workstation machining quality more reliable.

[0085] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the processing quality stability index includes:

[0086] For any given workstation, based on the change in the processing effectiveness index of the parts at that workstation, determine the processing effectiveness change index of each part at that workstation; and screen out stable expression parts based on the processing effectiveness change index.

[0087] Specifically, the methods for obtaining the processing performance change index and the stable expression of parts include:

[0088] For any part at any workstation, all parts in the same batch as that part within a historical time period are obtained as the historical parts corresponding to that part. The historical time period is a set of all historical moments whose time interval with the current moment is less than or equal to a preset duration. In this embodiment, the preset duration is one month.

[0089] The difference between the processing effectiveness index of any one part and the processing effectiveness index of each historical part is obtained sequentially and rounded down. The rounded down result of the difference is recorded as the processing effectiveness change index of any one part and each historical part.

[0090] The historical parts with a processing performance change index of 0 are denoted as the stable expression parts of any given part.

[0091] Furthermore, based on the change index of the processing performance of the stable expression parts at any given workstation and the proportion of the stable expression parts at any given workstation, the processing quality stability index of any given workstation is obtained.

[0092] Specifically, the methods for obtaining the processing quality stability index include:

[0093] The first historical part with a processing performance change index of -1 is denoted as the deterioration expression part of any given part.

[0094] The absolute value of the difference between the processing effectiveness index of any given part and its deteriorated expression part is inversely proportionally normalized and denoted as the stable base of any given part; wherein, the inversely proportional normalization process adopts... To present it using a model, The absolute value of the difference between the processing performance index of any given part and the deteriorated expression part;

[0095] The inversely proportional normalized result of the number of parts processed between any given part and the production time of its deteriorated expression part is denoted as the stability distance coefficient of that given part; wherein, the inversely proportional normalization process adopts... To present it using a model, The number of parts processed between the production time of any given part and its deteriorated expression part;

[0096] The ratio of the number of stable representation parts of any given part to the total number of historical parts in the same batch as any given part is recorded as the overall comparison index of any given part.

[0097] The product of the stability base, stability distance coefficient, and overall comparison index of any given part is denoted as the processing quality stability index of that given part. It should be noted that if no deteriorated part with a processing performance change index of -1 is found in the historical period, that is, all historical parts are stable, the processing quality stability index of that part is directly set to a constant of 1, and the calculation of the subsequent stability base and stability distance coefficient is skipped.

[0098] It should be noted that the higher the machining quality stability index of a part, the more stable the part's workstation is in the process of continuous precision boring, without any obvious quality deterioration or abnormal fluctuations. This indicates that the workstation has high machining consistency and repeatability under the current clamping conditions, tool wear status and process parameter configuration, and is less affected by random interference factors.

[0099] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the modified processing effectiveness index includes:

[0100] Obtain the average value of the processing effectiveness index of all parts at any workstation, and multiply the average value by the processing quality stability index of the workstation. This product is recorded as the corrected processing effectiveness index of the workstation.

[0101] It should be noted that the higher the correction processing effectiveness index of a workstation, the better the single-part processing effectiveness of that workstation in the current precision boring process, and the higher the stability of its processing quality over time. Therefore, the reliability of its processing effectiveness evaluation results is high.

[0102] Step S4: Determine the overall impact degree of each workstation based on the similarity between the same processing index sequences of different workstations; adjust the overall impact degree of each workstation based on the similarity of the processing index sequences of parts between workstations to obtain the adjusted impact degree of each workstation.

[0103] It should be noted that in scenarios where multiple workstations process simultaneously, the workstations are often coupled with each other through machine tool structural vibration, superposition of cutting forces, and heat transfer between fixtures and reference parts. This means that the processing result of a particular workstation is not entirely determined by its own state. Therefore, analyzing the similarity of each workstation on the same processing index sequence, and combining this with the similarity of the part processing index sequences between workstations, allows us to determine the degree to which corrections are affected at each workstation.

[0104] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the comprehensive degree of influence includes:

[0105] For any given workstation, obtain the surrounding workstations of that workstation and the positional relationship between that workstation and each of the surrounding workstations;

[0106] Based on the difference between the processing index sequence of any given workstation and each of its surrounding workstations, the degree of influence of any given workstation and each of its surrounding workstations on each processing index sequence is obtained.

[0107] Specifically, the ways in which the degree of expression is obtained are as follows:

[0108] The last part produced at any workstation is recorded as the latest part at that workstation.

[0109] Designate any workstation as the target workstation and any other workstation other than the target workstation as the reference workstation.

[0110] The absolute value of the difference between the last element of the same machining index sequence of the latest part at the target station and any reference station is denoted as the degree of influence of the target station and the reference station in that machining index sequence. For example, the absolute value of the difference between the last element of the coaxiality sequence of the latest part at the target station and any reference station is denoted as the degree of influence of the target station and the reference station in the coaxiality sequence.

[0111] It should be noted that in the scenario of simultaneous precision boring at multiple stations, under the same process parameters and clamping system, the machining indicators of the latest parts at each station should theoretically show similar final results. When there is a large difference between a target station and a reference station in the last element of the same machining indicator sequence, it indicates that the final machining effect of the two stations on that indicator has diverged significantly. This divergence is more likely due to the non-uniform effect of inter-station linkage factors at different stations, such as differences in structural vibration distribution, heat transfer path, or local clamping rigidity. Therefore, the greater the difference, the stronger the external influence on the machining indicator at the target station relative to the reference station, and the greater the degree of influence.

[0112] Furthermore, by utilizing the positional relationship between any given workstation and each of its surrounding workstations, the influence expression degree of any given workstation and each of its surrounding workstations is weighted and fused to obtain the influence degree of each processing indicator sequence of any given workstation.

[0113] Specifically, the methods for obtaining the degree of influence of indicators include:

[0114] Obtain the adjacency relationship between each reference workstation and the target workstation. The influence weight of the reference workstation adjacent to the target workstation is recorded as 0.7; the influence weight of the reference workstation not adjacent to the target workstation is recorded as 0.3.

[0115] The product of the influence weight of the target workstation and any reference workstation and the degree of influence expressed in any processing index sequence is denoted as the local influence degree of the target workstation and the reference workstation in that processing index sequence.

[0116] The linear normalization result of the mean local influence of the target workstation and all reference workstations in the processing index sequence is denoted as the index influence degree of the target workstation in this processing index sequence; wherein, the linear normalization method is the max-min normalization function.

[0117] Furthermore, based on the degree of influence of all processing index sequences of any given workstation, the overall degree of impact of any given workstation is obtained.

[0118] The sum of the influence of the target workstation on all processing indicator sequences is denoted as the overall impact of the target workstation.

[0119] It should be noted that the greater the overall impact on the target station, the more significant the differences between the various processing indicators of its parts and the corresponding indicators of other stations in the current multi-station precision boring process. This indicates that the processing results of this station are more susceptible to interference from inter-station coupling factors such as machine tool structure vibration, cutting force superposition, heat transfer, or fixture linkage. Its processing quality is highly sensitive to changes in the overall processing environment, and the reliability of judging its processing capability solely based on the processing performance of this station itself is relatively low.

[0120] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the degree of influence includes:

[0121] Based on the similarity of surface roughness between parts at different workstations, the workstations are divided into several wear clusters.

[0122] Specifically, the methods for obtaining wear clusters include:

[0123] For all workstations, DBSCAN clustering is performed based on the last element value of the surface roughness sequence of the latest part at each workstation. The clustering distance metric is the absolute value of the difference between the last element values ​​of the surface roughness sequence of the latest part at each workstation, resulting in several wear clusters. DBSCAN clustering is an existing technology, and the specific method will not be described here.

[0124] Furthermore, for any workstation in any wear cluster, the influence correction coefficient of the workstation is obtained based on the similarity of the processing index sequences of the workstation and other workstations in the wear cluster.

[0125] Specifically, the methods for obtaining the correction factor include:

[0126] Obtain the linearly normalized result of the cosine similarity between the latest part of the target station and any station in the same wear cluster in the same processing index sequence. The linearly normalized result of the cosine similarity between the target station and each processing index sequence of all the aforementioned stations in the same wear cluster is denoted as the similarity index of each processing index sequence of the target station. The linear normalization method is the max-min normalization function.

[0127] The mean of the similarity index of the target workstation across all processing index sequences is denoted as the influence correction coefficient of the target workstation.

[0128] It should be noted that the larger the influence correction coefficient of the target station, the more similar the changing trend and evolution of the target station and other stations in the wear cluster are in the sequence of various processing indicators. The processing quality fluctuation of the target station is more likely to come from common factors with similar tool wear, rather than from the clamping abnormality or local instability of the target station itself. This indicates that the target station has strong consistency in the group processing behavior and the correction of the overall influence degree is more reliable.

[0129] Furthermore, the overall impact degree of any one workstation is corrected using the aforementioned impact correction coefficient to obtain the corrected impact degree of any one workstation.

[0130] Specifically, the product of the impact correction coefficient of the target workstation and the overall impact level is denoted as the correction impact level of the target workstation.

[0131] It should be noted that the greater the impact of the correction on the target station, the stronger the external interference characteristics of the processing quality of that station. The processing results of its parts are greatly affected by the processing status of other stations, the overall working condition fluctuations, and the collective wear behavior, thus indicating that the uncertainty of the processing quality evaluation of that station is high.

[0132] Step S5: Obtain the processing quality index for each workstation based on the modified processing effectiveness index and the degree of impact of the modification, and adjust the precision boring process according to the processing quality index.

[0133] It should be noted that the corrected processing effectiveness index reflects the processing capability level of the workstation after analyzing historical stability, while the correction impact level reflects the strength of the interference of multiple workstations on the processing quality of the workstation. Therefore, by combining the corrected processing effectiveness index and the correction impact level, a processing quality index is constructed to measure the comprehensive ability of each workstation to stably output qualified parts in a real multi-workstation processing environment. Based on this, workstations that need parameter adjustment can be identified, thereby achieving targeted optimization of the precision boring process.

[0134] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the processing quality index includes:

[0135] Obtain the difference between the constant 1 and the degree of influence of the correction on the target station, and multiply the difference with the correction processing effectiveness index of the target station, and record it as the processing quality index of the target station.

[0136] Furthermore, stations with a processing quality index greater than or equal to a preset quality threshold are designated as normal stations, and the processing parameters of normal stations are not adjusted; wherein, the preset quality threshold is 0.8, and this embodiment will be described using this as an example;

[0137] Workstations with a processing quality index lower than the preset quality threshold are recorded as abnormal workstations.

[0138] For any abnormal workstation, the indicator corresponding to the processing indicator sequence with the greatest influence among all processing indicator sequences of that workstation is recorded as the main influencing indicator of that abnormal workstation.

[0139] Targeted process adjustments will be implemented based on the key influencing indicators. Specific adjustment methods include:

[0140] If coaxiality is the main influencing indicator of abnormal workstations, since coaxiality is mainly affected by the datum accuracy of clamping and positioning, and the coaxiality of the machine tool spindle and fixture, it is necessary to recalibrate the fixture positioning datum, repair the wear of the positioning pins and stops, and correct the coaxiality of the machine tool spindle and worktable.

[0141] If roundness is the main influencing indicator of abnormal workstations, since roundness is mainly affected by the radial runout of the tool and the stability of the cutting force, it is necessary to replace the high-precision boring bar, shorten the tool overhang length, reduce the precision boring depth, and reduce the fluctuation of cutting force.

[0142] If the hole diameter is the main influencing factor of abnormal workstations, since the hole diameter is mainly affected by the fine adjustment amount of the precision boring tool and the cutting parameters, it is necessary to improve the fine adjustment accuracy of the boring tool and adjust the cutting speed.

[0143] If surface roughness is the main influencing factor of abnormal workstations, since surface roughness is mainly affected by feed rate, tool cutting edge quality, and cutting fluid lubrication performance, it is necessary to reduce the fine boring feed rate, replace the cutting tool with a sharper one, and replace the cutting fluid with a high-lubricity one.

[0144] The adjusted process parameters are applied to the next precision boring operation with repeated clamping, and the processing index sequence is re-acquired to enter a new round of calculation process S1-S5 to verify whether the adjustment is effective.

[0145] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0146] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for precision boring of circumferential parts by repeated clamping, characterized in that, The method includes: The process involves obtaining a sequence of machining indicators for each part at each workstation during precision boring, along with a reference value for each machining indicator sequence. Specifically, the precision boring process is divided into several discrete detection nodes. The machining indicators of all detection nodes for each part are arranged to obtain a sequence of machining indicators for each part at each workstation. The machining indicators include coaxiality, roundness, surface roughness, and hole diameter error. The reference value is the process standard value corresponding to the machining indicator sequence. Based on the changes in the processing index sequence of each part at each workstation and the difference from the reference value, the improvement index of each part at each workstation in each processing index sequence is determined, and qualified index sequences are screened; based on the improvement index and the number of qualified index sequences, the processing effectiveness index of each part at each workstation is determined. The method for obtaining the improvement index includes: For any part at any workstation and any processing index sequence, the delay improvement index of the processing index sequence is determined based on the slope of the fitted line of the elements in the processing index sequence. The standard scoring index of any processing indicator sequence is determined based on the difference between the last element value in any processing indicator sequence and the reference value of any processing indicator sequence. Based on the delay improvement index and the standard scoring index, the improvement index of any processing index sequence is obtained; The specific method for obtaining the improvement index of any processing indicator sequence based on the delay improvement index and the standard scoring index is as follows: The average of the delay improvement index and the standard scoring index is denoted as the improvement index of any processing index sequence. The methods for obtaining the processing effectiveness index include: For any part at any workstation, determine the pass rate index of the part based on the proportion of the pass rate index sequence of the part in all processing index sequences. Based on the overall situation of the improvement index of all processing index sequences of any given part, determine the comprehensive improvement index of any given part; Based on the pass rate index and the comprehensive improvement index of any one part, the processing effectiveness index of any one part is determined; specifically, the linear normalized result of the product of the pass rate index and the comprehensive improvement index of any one part is denoted as the processing effectiveness index of any one part. The method for obtaining the qualified indicator sequence includes: For any part at any workstation and any processing index sequence, if the standard scoring index of the processing index sequence is greater than the preset pass threshold, the processing index sequence is recorded as the pass index sequence of the part. Based on the changes in the processing effectiveness index of each station during multiple consecutive precision boring operations of parts, a processing quality stability index for each station is determined; based on the processing effectiveness index and the processing quality stability index, a corrected processing effectiveness index for each station is determined. The method for obtaining the processing quality stability index includes: For any given workstation, based on the change in the processing effectiveness index of the parts at that workstation, determine the processing effectiveness change index of each part at that workstation; and screen out stable expression parts based on the processing effectiveness change index. Based on the change index of the processing performance of stable expression parts at any given workstation, and the proportion of stable expression parts at any given workstation, the processing quality stability index of that workstation is obtained; the method for obtaining the modified processing performance index includes: Obtain the average value of the processing effectiveness index of all parts at any workstation, and multiply the average value by the processing quality stability index of the workstation to denot the corrected processing effectiveness index of the workstation. Based on the similarity between the same processing index sequences of different workstations, the overall impact degree of each workstation is determined; based on the similarity of the processing index sequences of parts between workstations, the overall impact degree of each workstation is corrected to obtain the corrected impact degree of each workstation. The method for obtaining the overall degree of impact includes: For any given workstation, obtain the surrounding workstations of that workstation and the positional relationship between that workstation and each of the surrounding workstations; Based on the difference in the processing index sequence of any one workstation and each of its surrounding workstations, the degree of influence of any one workstation and each of its surrounding workstations on each processing index sequence is obtained. By utilizing the positional relationship between any given workstation and each of its surrounding workstations, the degree of influence of any given workstation and each of its surrounding workstations is weighted and fused to obtain the degree of influence of each processing indicator sequence of any given workstation. Based on the degree of influence of all processing index sequences of any given workstation, the overall degree of impact of any given workstation is obtained. The processing quality index of each station is obtained based on the modified processing effectiveness index and the degree of impact of the modification, and the precision boring process is adjusted according to the processing quality index. The method for obtaining the processing quality index includes: For any workstation, the normalized result of the product of the reciprocal of the degree of influence of the correction on the workstation and the correction processing effectiveness index is denoted as the processing quality index of the workstation.

2. The precision boring method for repeatedly clamping circular parts according to claim 1, characterized in that, The method for obtaining the degree of impact of the correction includes: The processing index sequence includes a surface roughness sequence, which is composed of the surface roughness of any part collected during the precision boring process of repeated clamping of a circumferential part. Based on the similarity of surface roughness between parts at different workstations, the workstations are divided into several wear clusters; For any workstation in any wear cluster, the influence correction coefficient of the workstation is obtained based on the similarity of the processing index sequence of the workstation to other workstations in the wear cluster. The overall impact degree of any workstation is corrected by using the aforementioned impact correction coefficient to obtain the corrected impact degree of any workstation.

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