CN109522522B - Method for generating and applying envelope curve of press-fitting and screwing curve - Google Patents
Method for generating and applying envelope curve of press-fitting and screwing curve Download PDFInfo
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Abstract
The invention relates to a method for generating and applying press-fitting and tightening curve envelope lines, which comprises the steps of firstly, setting envelope line generating parameters, an envelope line algorithm and an envelope line mode; then according to a group of qualified curves, calculating an upper envelope curve and a lower envelope curve of the qualified curves by configuring set envelope parameters, an envelope algorithm and an envelope mode; whether the press fitting and screwing process meets the requirements is judged according to whether the actual process production data is between the upper envelope line and the lower envelope line. A series of parameters and specific algorithms are applied, after a complete envelope curve is generated through a group of qualified curves, two envelope curves above and below the qualified curve are generated for process control, fine adjustment correction can be given to the press fitting and screwing processes according to the process before control, therefore, more accurate press fitting and screwing control is obtained, the method is different from a broken line mode of fixing the number of points in the past, and therefore the monitoring precision of the press fitting and screwing processes is improved.
Description
Technical Field
The invention relates to a production data processing technology, in particular to a method for generating and applying envelope curves of press-fitting and screwing curves.
Background
The conventional curve envelope generation mode in the current market is generally that a fixed number of points are connected into a broken line, and the defects of the mode are mainly that the number of points is small, the envelope with high fitting degree cannot be formed, and wrong judgment is easily caused in a curve with more radians. Therefore, it is necessary to design a method capable of generating fully-fitted and accurately-described envelope curves, and by selecting certain qualified curves and generating envelope curves with different requirements according to different parameters, more accurate envelope curve control is realized compared with the traditional method using broken lines.
Disclosure of Invention
The invention provides a method for generating and applying envelope curves of press fitting and screwing curves, aiming at the problem that the envelope curves of the existing press fitting and screwing curves are not high in precision.
The technical scheme of the invention is as follows: a method for generating and applying envelope curve of press-fitting and screwing curve includes setting generation envelope parameter, envelope algorithm and envelope mode; then according to a group of qualified curves, calculating an upper envelope curve and a lower envelope curve of the qualified curves by configuring set envelope parameters, an envelope algorithm and an envelope mode; whether the press fitting and screwing process meets the requirements is judged according to whether the actual process production data is between the upper envelope line and the lower envelope line.
The envelope parameters comprise the starting time of data sampling, the ending time of the data sampling, the maximum sample number, the granularity, the envelope algorithm, the maximum point number participating in calculation on the whole envelope curve, the minimum value of an X axis, the maximum value of the X axis, a dynamic alignment mode and parameters under a set mode;
wherein the granularity is as follows: the X-axis numerical values of different curves cannot be in one-to-one correspondence, a range of an X-axis is set to be called granularity, the curve is divided into a plurality of sections according to the range, data in each section are regarded as the same characteristic point on the curve, and envelope curve algorithm processing is carried out.
The envelope algorithm comprises three algorithms of maximum minimum value + fixed value, average value +3 sigma and average value + fixed value, and one of the three algorithms is selected for application:
maximum minimum + fixed value algorithm: respectively taking the maximum value and the minimum value of a Y axis as Y axis values at curve points on each granularity, taking the average value of the corresponding X axes as X axis values to be summarized into two curves, and adding a fixed value to the Y axis value of the maximum value curve and subtracting the fixed value from the Y axis value of the minimum value curve;
mean +3 σ algorithm: respectively averaging all X-axis values and Y-axis values at curve points on each granularity, calculating a standard deviation sigma of a Y-axis value, adding 3 sigma to the Y-axis average value, subtracting 3 sigma from the Y-axis average value to obtain a Y-axis value, and taking the corresponding X-axis average value as an X-axis value to form two curves;
mean + fixed value algorithm: and respectively averaging all the X-axis and Y-axis curve points on each granularity, adding or subtracting a fixed value from the average value of the Y-axis to obtain a Y-axis value, and using the corresponding average value of the X-axis as two curves of the X-axis value group.
The envelope patterns are of two kinds: first standard mode: analyzing by using original X \ Y axis data; second independent torque mode: the Y-axis raw data is maintained and the X-axis data is replaced with an incremental sequence.
The dynamic alignment mode is to avoid the situation that the torque rising angle is different from front to back, and reasonable envelope setting cannot be obtained through direct processing, and specifically comprises two modes of initial threshold value alignment and peak value alignment;
the initial threshold mode refers to that the first granularity curve reaches a set threshold point for the first time and is recorded as a standard point, then all granularity curves find the threshold point in the same way, the X value of the point minus the X value of the standard point is recorded as a deviation value, and the X values of all points on the corresponding granularity curves are subtracted by the deviation value, so that the aim of initial threshold alignment with the first granularity curve is fulfilled;
the peak alignment mode is to use the peak of the first particle size curve as a standard point, then to subtract the X values of the standard point from the X values of the peaks of all the particle size curves to obtain a deviation value, and to subtract the X values of all the points on the particle size curves to obtain the peak alignment with the first particle size curve.
The invention has the beneficial effects that: the method for generating and applying the envelope curve of the press fitting and tightening curve applies a series of parameters and a specific algorithm, generates a complete envelope curve through a group of qualified curves, and is different from the traditional broken line mode of fixing point numbers, so that the monitoring precision of the press fitting and tightening process is improved.
Drawings
FIG. 1 is a graph of an original curve envelope;
FIG. 2 is a graph illustrating the number of rebounds to be processed after threshold point alignment according to the present invention;
FIG. 3 is a graph of the effect of the invention after the rebound number curve processing;
fig. 4 is a schematic diagram of the complete and accurate envelope finally generated by the present invention.
Detailed Description
A method for generating envelope curves of press-fitting and tightening curves comprises the steps of setting parameters including starting time, ending time, maximum sample number, envelope curve algorithm, offset, maximum point number, X-axis maximum value, X-axis minimum value, dynamic alignment, alignment mode, alignment threshold value, target tolerance, angle range, X-axis point number, granularity and envelope curve mode. And then, according to a group of qualified curves, an upper envelope line and a lower envelope line of the qualified curves are calculated by configuring set envelope line parameters, an envelope line algorithm and an envelope line mode, whether the press fitting and screwing process meets the requirements or not is judged more accurately according to whether actual process production data are between the upper envelope line and the lower envelope line, and fine adjustment correction (process adjustment) can be given to the press fitting and screwing process according to the result, so that more accurate press fitting and screwing control is obtained.
The envelope generation specifically comprises the following steps:
1. data acquisition: data is collected in real time, including but not limited to the following: torque, angle, speed, serial number, peak value, etc.
2. Setting parameters:
starting time: the earliest time of generation of the historical curve stored in the database.
End time: the latest generation time of the historical curve stored in the database.
Maximum number of samples: and setting the upper limit of the number of the curve samples searched in the time range, and if the actual number exceeds the number, acquiring according to the set value.
The granularity is as follows: the X-axis numerical values of different curves cannot be in one-to-one correspondence, a range of an X-axis is set to be called granularity, the curve is divided into a plurality of sections according to the range, data in each section are regarded as the same characteristic point on the curve, and envelope curve algorithm processing is carried out.
Envelope algorithm: the method comprises three algorithms of maximum minimum value + fixed value, average value +3 sigma and average value + fixed value, and one of the three algorithms is selected for application.
Maximum minimum + fixed value algorithm: and respectively taking the maximum value and the minimum value of the Y axis as Y axis values at curve points on each granularity, taking the average value corresponding to the X axis as the X axis value to be summarized into two curves, and adding a fixed value to the Y axis value of the maximum value curve and subtracting the fixed value from the Y axis value of the minimum value curve.
Mean +3 σ algorithm: and (3) respectively averaging all the X-axis values and all the Y-axis values at curve points on each granularity, calculating the standard deviation (sigma) of the Y-axis values, adding 3 sigma to the Y-axis average value, subtracting 3 sigma from the Y-axis average value to obtain a Y-axis value, and taking the corresponding X-axis average value as an X-axis value to form two curves.
Mean + fixed value algorithm: and respectively averaging all the X-axis and Y-axis curve points on each granularity, adding or subtracting a fixed value from the average value of the Y-axis to obtain a Y-axis value, and using the corresponding average value of the X-axis as two curves of the X-axis value group.
Maximum points: how many points on the whole envelope curve are taken at maximum to participate in the calculation.
Minimum value of X axis: the X-axis takes the minimum value and points on the X-axis less than this value are discarded.
Maximum value of X axis: the X-axis takes the maximum value and points with X-axis greater than this are discarded.
Envelope mode: 1. standard mode: analyzing by using original X \ Y axis data; 2. independent torque (pressure) mode: the Y-axis raw data is maintained and the X-axis data is replaced with an incremental sequence.
Dynamic alignment: and performing an alignment mode on the X axis of the effective judgment range of the curve through certain parameters and algorithms, specifically dividing the alignment mode into an initial threshold value and a peak value alignment mode. The initial threshold mode refers to that the first granularity curve reaches a threshold point for the first time and is recorded as a standard point (the threshold point is generally set to be a numerical value which is 5-10% of the rated range of a screwing and pressing tool, for example, a tool with 100Nm, and the threshold value is generally set to be 10Nm), then all the granularity curves find the threshold point in the same way, the X value of the point minus the X value of the standard point is recorded as a deviation value, and the X values of all points on the corresponding granularity curves are subtracted by the deviation value, so that the purpose of performing initial threshold alignment with the first granularity curve is achieved. The peak alignment mode is to use the peak of the first particle size curve as a standard point, then to subtract the X values of the standard point from the X values of the peaks of all the particle size curves to obtain a deviation value, and to subtract the X values of all the points on the particle size curves to obtain the peak alignment with the first particle size curve.
Target value: the target value in the initial threshold mode is the threshold value and the target value in the peak mode is the peak value.
Target tolerance: starting a peak mode, wherein the peak mode is a slip value proportion, the purpose of the parameter is to detect whether a slip point is reached, traverse the data of the Y axis, record a maximum value, and judge that the maximum value is a peak value when a difference value behind the maximum value is larger than or equal to a set tolerance.
Launch value (angle, displacement): from the point after this value, the calculation is only engaged and partial interference points can be filtered out.
Positive direction of X axis: the peak mode is enabled, taking the maximum number of points forward to the X-axis starting with the peak (the largest peak in the entire curve).
Negative X-axis: the peak mode is enabled, taking the maximum number of points forward to the X-axis starting from the peak.
3. The calculation method comprises the following steps:
setting three parameters of starting time, ending time and maximum number of samples to select a curve sample in a certain time interval;
the envelope algorithm comprises three modes of 'maximum minimum value + value', 'average value +3 sigma' and 'average value + value', and different process requirements are met respectively; the minimum value of the X axis and the maximum value of the X axis are set, so that data in the effective stroke can be screened out according to requirements; when the pre-tightening distance is not fixed, dynamic torque needs to be set to align the curves, as shown in fig. 1, the rising angles of the Y-axis torque (Nm) of the original curves are different before and after, a reasonable envelope curve cannot be obtained by direct processing, a threshold value most aligned standard needs to be set, the threshold values of all the curves are aligned, and then the envelope curve is calculated, as shown in fig. 2, the torque threshold value set in this example is 2 Nm; meanwhile, there is a springback number curve in fig. 2, this data is not analytically meaningful and needs to be processed, an envelope curve mode is set to process the springback curve and then calculated, the processing effect is as shown in fig. 3, the uppermost connecting solid line is an effective curve, and the lower connecting line is a rejected part. The reason for the spring back curve is that the tightening process may be divided into several stages, and the transition may be stopped when the tool to be tightened does not apply torque, and the part may be rotated in a small reverse direction by elastic deformation of the tool, resulting in a decrease in torque and a reduction in angle. This part is not data generated during tightening and needs to be analyzed after being rejected.
Finally, a complete and precise envelope (upper and lower) is generated by these parameters as shown in fig. 4, and the press fitting and tightening can be precisely controlled.
Claims (2)
1. A method for generating and applying envelope curve of press-fitting and screwing curve is characterized in that firstly, envelope parameter generation, envelope algorithm and envelope mode are set; then according to a group of qualified curves, calculating an upper envelope curve and a lower envelope curve of the qualified curves by configuring set envelope parameters, an envelope algorithm and an envelope mode; whether the press fitting and screwing process meets the requirements is judged according to whether the actual process production data is between the upper envelope line and the lower envelope line, and fine adjustment correction is given to the press fitting and screwing process according to the result to obtain more accurate press fitting and screwing control;
the envelope parameters comprise the starting time of data sampling, the ending time of the data sampling, the maximum sample number, the granularity, the maximum number of points participating in calculation on the whole envelope curve, the minimum value of an X axis, the maximum value of the X axis, a dynamic alignment mode and parameters under a set mode;
wherein the granularity is as follows: the X-axis numerical values of different curves cannot be in one-to-one correspondence, a range of an X-axis is set to be called granularity, the curve is divided into a plurality of sections according to the range, data in each section are regarded as the same characteristic point on the curve, and envelope curve algorithm processing is carried out;
the envelope algorithm comprises three algorithms of maximum minimum value + fixed value, average value +3 sigma and average value + fixed value, and one of the three algorithms is selected for application:
maximum minimum + fixed value algorithm: respectively taking the maximum value and the minimum value of a Y axis as Y axis values at curve points on each granularity, taking the average value of the corresponding X axes as X axis values to be summarized into two curves, and adding a fixed value to the Y axis value of the maximum value curve and subtracting the fixed value from the Y axis value of the minimum value curve;
mean +3 σ algorithm: respectively averaging all X-axis values and Y-axis values at curve points on each granularity, calculating a standard deviation sigma of a Y-axis value, adding 3 sigma to the Y-axis average value, subtracting 3 sigma from the Y-axis average value to obtain a Y-axis value, and taking the corresponding X-axis average value as an X-axis value to form two curves;
mean + fixed value algorithm: and respectively averaging all the X-axis and Y-axis curve points on each granularity, adding or subtracting a fixed value from the average value of the Y-axis to obtain a Y-axis value, and using the corresponding average value of the X-axis as two curves of the X-axis value group.
2. The method for generating and applying the envelope curve of the press-fitting and tightening curves according to claim 1, wherein the dynamic alignment mode is to avoid that the torque rising angles are different before and after, and reasonable envelope curve settings cannot be obtained by direct processing, and specifically comprises two types of initial threshold values and peak value alignment;
the initial threshold mode refers to that the first granularity curve reaches a set threshold point for the first time and is recorded as a standard point, then all granularity curves find the threshold point in the same way, the X value of the point minus the X value of the standard point is recorded as a deviation value, and the X values of all points on the corresponding granularity curves are subtracted by the deviation value, so that the aim of initial threshold alignment with the first granularity curve is fulfilled;
the peak alignment mode is to use the peak of the first particle size curve as a standard point, then to subtract the X values of the standard point from the X values of the peaks of all the particle size curves to obtain a deviation value, and to subtract the X values of all the points on the particle size curves to obtain the peak alignment with the first particle size curve.
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| CN113829034B (en) * | 2020-06-24 | 2022-12-09 | 华晨宝马汽车有限公司 | Quality monitoring method, system and equipment based on bolt tightening working curve |
| CN114850847A (en) * | 2021-02-04 | 2022-08-05 | 中国航发商用航空发动机有限责任公司 | Pipe joint assembling quality detection method |
| CN113031524B (en) * | 2021-02-07 | 2022-06-17 | 南京航空航天大学 | Cubic spline-based press fitting force envelope curve generation method |
| CN113899538B (en) * | 2021-09-29 | 2023-09-05 | 上汽大众汽车有限公司 | Bolt tightening monitoring method and system |
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