A high-precision measurement method and system for O-ring dimensions

Abstract

The present application relates to the technical field of ultrasonic thickness measurement of intelligent sensors, and specifically to a method and system for high-precision measurement of the size of an O-ring, the method comprising: determining the envelope evaluation factor of each echo envelope of each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, combined with the envelope similarity and the time difference between each echo envelope of each scanning point on the O-ring and the echo envelope of the same corresponding order in other scanning points, so as to measure the size of the O-ring. The present application improves the recognition accuracy of the echo envelope of the inner ring of the O-ring and the accuracy of measuring the cross-sectional diameter of the O-ring by analyzing the time domain morphological similarity characteristics and frequency domain fundamental frequency difference characteristics of the echo envelope at a single scanning point, as well as the correlation characteristics of the echo envelope in the time interval caused by the multipath effect.

Description

Technical Field

[0001] The present application relates to the technical field of ultrasonic thickness measurement with intelligent sensors, and in particular to a method and system for high-precision measurement of the dimensions of an O-ring. Background Art

[0002] An O-ring is a sealing rubber ring with a circular cross section, usually made of synthetic materials such as rubber, silicone, polytetrafluoroethylene and polyurethane. Because of its good sealing effect and low price, it is widely used in various types of machinery and industrial equipment. The accuracy of the O-ring will determine its sealing performance, compatibility and reliability. The field of high-precision technology places high demands on the accuracy of the O-ring size, so it is very necessary to perform high-precision measurement on the synthesized O-ring.

[0003] O-rings mainly contain two size parameters: inner diameter and cross-sectional diameter (abbreviated as cross-sectional diameter). The size of O-rings is often small, so high-precision ultrasonic waves are usually used to measure the size of O-rings. The inner diameter is larger and is often easier to measure. However, for cross-sectional radii with small curvature, when the scanning point is located on the cross-sectional radius of small curvature, the ultrasonic wave may encounter more curved surface edges during propagation, resulting in increased reflection and scattering, thereby affecting the accuracy of measuring the size of the O-ring. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for high-precision measurement of the size of an O-ring. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for high-precision measurement of the size of an O-ring, the method comprising the following steps:

[0006] Obtain all reflected pulse signals after the ultrasonic pulse signal is reflected from each scanning point on the O-ring, and extract the echo envelope of all reflected pulse signals from each scanning point on the O-ring by using the envelope detection method;

[0007] Determine the envelope similarity of each echo envelope at each scanning point on the O-ring according to the smoothness of each echo envelope at each scanning point on the O-ring and the difference between each echo envelope and the reflected pulse signal in the first echo envelope;

[0008] Obtaining the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, and determining the echo confidence of each echo envelope of each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal and combining the envelope similarity;

[0009] Determine the envelope evaluation factor of each echo envelope of each scanning point on the O-ring according to the time difference between each echo envelope of each scanning point on the O-ring and the echo envelopes of the same corresponding order in other scanning points, combined with the echo confidence;

[0010] Based on the envelope evaluation factor of all echo envelopes of each scanning point on the O-ring, combined with the time and speed at which the first echo envelope is received at each scanning point, the intercept diameter of each scanning point on the O-ring is determined;

[0011] The size of the O-ring is measured based on the maximum and minimum values ​​of the intercept diameters of all scanning points on the O-ring.

[0012] Preferably, the method for determining the envelope similarity of each echo envelope at each scanning point on the O-ring is:

[0013] Analyze the goodness of fit of each echo envelope at each scanning point on the O-ring;

[0014] All reflected pulse signals corresponding to each echo envelope of each scanning point on the O-ring constitute the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring;

[0015] Analyze the distance between the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring and the ultrasonic reflection sequence of the first echo envelope;

[0016] The envelope similarity of each echo envelope of each scanning point on the O-ring is the ratio of the goodness of fit of each echo envelope of each scanning point on the O-ring to the distance.

[0017] Preferably, the method for determining the echo confidence of each echo envelope of each scanning point on the O-ring is:

[0018] Determine the fundamental frequency deviation of each echo envelope at each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope at each scanning point on the O-ring and the frequency of the ultrasonic pulse signal;

[0019] The expression of the echo confidence of each echo envelope at each scanning point on the O-ring is: In the formula, A i,j Indicates the echo confidence of the jth echo envelope at the i-th scanning point on the O-ring; B i,j represents the envelope similarity of the jth echo envelope at the i-th scanning point on the O-ring; C i,j It represents the fundamental frequency deviation of the jth echo envelope at the i-th scanning point on the O-ring; γ is a preset constant greater than 0.

[0020] Preferably, the fundamental frequency deviation of each echo envelope of each scan on the O-ring is the absolute value of the difference between the fundamental frequency of each echo envelope of each scan point on the O-ring and the frequency of the ultrasonic pulse signal.

[0021] Preferably, the method for determining the envelope evaluation factor of each echo envelope at each scanning point on the O-ring is:

[0022] Determine the echo time difference of each echo envelope of each scanning point on the O-ring according to the time difference between each echo envelope of each scanning point on the O-ring and the echo envelopes of the same corresponding order in other scanning points;

[0023] The envelope evaluation factor of each echo envelope of each scanning point on the O-ring is the ratio of the echo confidence of each echo envelope of each scanning point on the O-ring to the echo time difference.

[0024] Preferably, the expression for the echo time difference of each echo envelope at each scanning point on the O-ring is: In the formula, Represents the echo time difference of the jth echo envelope at the i-th scanning point on the O-ring; represents the intersection-and-joint ratio of the i-th scanning point on the O-ring and the k-th scanning point on the j-th echo envelope corresponding time interval; N represents the number of all scanning points on the O-ring; γ is a preset constant greater than 0.

[0025] Preferably, the method for determining the cross-sectional diameter of each scanning point on the O-ring is:

[0026] Based on the envelope evaluation factor of all echo envelopes of each scanning point on the O-ring, combined with the time when the first echo envelope is received at each scanning point on the O-ring, the ultrasonic flight time of each scanning point on the O-ring is determined;

[0027] Obtain the propagation speed of ultrasonic waves in the O-ring. The expression of the intercept diameter at each scanning point on the O-ring is: Where, d i represents the intercept diameter of the i-th scanning point on the O-ring; v represents the propagation speed of the ultrasonic wave in the O-ring; ToF i Represents the ultrasonic flight time of the i-th scanning point on the O-ring.

[0028] Preferably, the method for determining the ultrasonic flight time of each scanning point on the O-ring is:

[0029] Except for the first echo envelope of each scanning point on the O-ring, the echo envelope corresponding to the maximum envelope evaluation factor of each scanning point on the O-ring is used as the inner ring echo envelope of each scanning point on the O-ring;

[0030] The ultrasonic flight time of each scanning point on the O-ring is the difference between the time when each scanning point on the O-ring receives the inner ring echo envelope and the time when the first echo envelope is received.

[0031] Preferably, the measuring of the size of the O-ring comprises:

[0032] The difference between the minimum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the lower limit of the tolerance range of the O-ring, and the difference between the maximum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the upper limit of the tolerance range of the O-ring;

[0033] The tolerance range of the O-ring is preset. If the tolerance range of the O-ring is a subset of the tolerance range, the size of the O-ring is qualified, otherwise, the size of the O-ring is unqualified.

[0034] In a second aspect, an embodiment of the present application further provides a high-precision measurement system for the dimensions of an O-ring, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the system implements the steps of any one of the above-mentioned methods for high-precision measurement of the dimensions of an O-ring.

[0035] This application has at least the following beneficial effects:

[0036] The present application determines the echo confidence of each echo envelope of each scanning point on the O-ring by analyzing the smoothness of each echo envelope of each scanning point on the O-ring, the difference between each echo envelope of each scanning point on the O-ring and all corresponding reflected pulse signals in the first echo envelope, and combining the difference between the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, so as to eliminate the interference of false envelopes caused by clutter or environmental noise on the O-ring size measurement.

[0037] The present application obtains the echo time difference of each echo envelope of each scanning point on the O-ring by analyzing the time difference between each echo envelope of each scanning point on the O-ring and the echo envelope of the same corresponding order in other scanning points, and combines the correlation characteristics of the envelope in the time interval caused by the multipath effect, so as to eliminate the interference of the redundant envelope caused by the multipath effect on the size measurement of the O-ring; based on the echo confidence and the echo time difference, the envelope evaluation factor of each echo envelope of each scanning point on the O-ring is obtained, thereby obtaining the intercept diameter of each scanning point on the O-ring, and finally combining the intercept diameters of all scanning points to detect the quality of the O-ring.

[0038] The present application eliminates the interference of false envelopes caused by clutter or environmental noise and redundant envelopes caused by multipath effects on O-ring size measurement by analyzing the time domain morphological similarity characteristics and frequency domain fundamental frequency difference characteristics of the echo envelope at a single scanning point, as well as the correlation characteristics of the echo envelope in the time interval caused by the multipath effect, thereby improving the recognition accuracy of the echo envelope of the inner ring of the O-ring and the accuracy of measuring the cross-sectional diameter of the O-ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 A flowchart of a method for high-precision measurement of the size of an O-ring provided in one embodiment of the present application;

[0041] Figure 2 A schematic diagram of the inner diameter of the O-ring provided in this application;

[0042] Figure 3 A schematic diagram of the distribution of scanning points of the O-ring provided for this application;

[0043] Figure 4 Schematic diagram of ultrasonic scanning of O-ring provided in this application;

[0044] Figure 5 Schematic diagram of the envelope evaluation factor extraction process provided for this application;

[0045] Figure 6 Schematic diagram of the O-ring size measurement process provided in this application. DETAILED DESCRIPTION

[0046] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of a high-precision measurement method and system for the size of an O-ring proposed in the present application, its specific implementation, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0047] Unless defined otherwise, 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 application belongs.

[0048] The specific scheme of a high-precision measurement method and system for the size of an O-ring provided by the present application is described in detail below with reference to the accompanying drawings.

[0049] See also Figure 1 , which shows a flow chart of a method for high-precision measurement of the size of an O-ring provided by an embodiment of the present application, the method comprising the following steps:

[0050] Step S1: Obtain a reflected pulse signal at each scanning point on the O-ring.

[0051] O-ring size parameters mainly include two parameters:

[0052] Inner diameter: The diameter corresponding to the inner circumference of the O-ring in the free state, which is the diameter size that contacts the inner wall of the groove when installed in the sealing groove.

[0053] Cross-sectional diameter: The diameter of the cross section of the O-ring in a free state, which is crucial to the compression and sealing energy of the O-ring.

[0054] Preferably, the schematic diagram of the inner diameter of the O-ring provided in the present application is as follows: Figure 2 As shown. Among them, d 0 Indicates the inner diameter of the O-ring; d 1 Indicates the cross-sectional diameter of the O-ring; the left side is a plan view of the O-ring, and the right side is a cross-sectional view of the O-ring.

[0055] An ultrasonic thickness gauge is used to measure the reflected pulse signals at multiple scanning points on the O-ring to be tested. The ultrasonic thickness gauge contains a transmitting crystal and a receiving crystal, wherein the transmitting crystal is used to transmit the ultrasonic pulse signal, and the frequency of the ultrasonic pulse signal is f 1 The receiving crystal is used to receive the reflected pulse signal reflected back from the ultrasonic pulse signal arriving at the scanning point.

[0056] Collect the reflected pulse signal at each scanning point on the O-ring, the sampling frequency is f 2 .

[0057] It should be noted that the frequency f of the ultrasonic pulse signal 1 and the sampling frequency f of the received signal 2 The value of is artificially set. In this embodiment, f 1 The value of f is 20MHz, 2 The value of is 200MHz, and the implementer can also set it according to the specific situation. This embodiment does not impose any special limitation.

[0058] Preferably, the schematic diagram of the distribution of the scanning points of the O-ring provided in the present application is as follows: Figure 3 As shown. Among them, 1 represents the cross-sectional line of the O-ring, that is, the center line of the inner ring and the outer ring; 2 represents the position of each scanning point on the O-ring.

[0059] Preferably, the schematic diagram of ultrasonic scanning of an O-ring provided in the present application is as follows: Figure 4 As shown. Among them, 1 represents the probe of the ultrasonic thickness gauge, including the transmitting crystal and the receiving crystal; 2 represents the cross section of the O-ring; 3 represents the echo of the outer surface of the O-ring; 4 represents the echo of the inner surface of the O-ring.

[0060] Step S2: Determine the echo confidence of each echo envelope at each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope at each scanning point on the O-ring and the frequency of the ultrasonic pulse signal and in combination with the envelope similarity.

[0061] Ideally, there are two echo envelopes in the reflected pulse signal of each scanning point on the O-ring. Since the curvature of the O-ring cross section is small, and it may be accompanied by roughness, scratches, and oil stains on the surface of the O-ring, which affects the reflection and propagation of the ultrasonic wave, there are multiple echo envelopes in the reflected pulse signal of each scanning point on the O-ring. The existence of multiple echo envelopes makes it difficult to accurately determine the ultrasonic flight time of the ultrasonic wave at each scanning point on the O-ring, thus affecting the measurement of the size of the O-ring. Therefore, it is necessary to analyze all the reflected pulse signals of each scanning point on the O-ring, specifically:

[0062] In order to extract the echo envelope information, all reflected pulse signals at each scanning point on the O-ring are used as the input of the envelope detection method, and a segmentation threshold is set. The echo envelope with an amplitude greater than the segmentation threshold is used as the echo envelope to be analyzed, and multiple echo envelopes of each scanning point on the O-ring are obtained.

[0063] It should be noted that there are many commonly used envelope detection methods. In this embodiment, Hilbert transform is used to extract each echo envelope of all reflected pulse signals at each scanning point on the O-ring. The implementer may also use other envelope detection methods such as short-time Fourier transform, and this embodiment does not impose any special restrictions.

[0064] Among them, Hilbert transform is a well-known technology in signal processing, and the specific process of extracting the envelope is not repeated here.

[0065] It should be understood that the value of the segmentation threshold is artificially set. In this embodiment, the value of the segmentation threshold is 5mv. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0066] S201: envelope similarity of each echo envelope of each scanning point on the O-ring.

[0067] After the ultrasonic wave is emitted from the transmitting crystal, it first encounters the outer surface of the O-ring which is closest to the transmitting crystal. Since the outer surface of the O-ring is closer to the transmitting crystal and less likely to be interfered with, the first echo envelope of each scanning point of the O-ring is taken as the echo envelope of the outer surface of the O-ring, and the analysis is mainly focused on the envelopes other than the first echo envelope.

[0068] The echo envelope of the real O-ring surface often fluctuates smoothly and is basically consistent with the frequency deviation of the ultrasonic pulse signal. However, the echo envelope caused by clutter often fluctuates chaotically, and the fundamental frequency of the echo envelope deviates greatly from the frequency of the ultrasonic pulse signal due to the interference of environmental noise. Therefore, based on the smoothness of each echo envelope at each scanning point on the O-ring, and the difference between each echo envelope at each scanning point on the O-ring and all corresponding reflected pulse signals in the first echo envelope, the envelope similarity of each echo envelope at each scanning point on the O-ring is determined to distinguish the real echo of the inner surface of the O-ring from the clutter caused by environmental noise or other factors, specifically:

[0069] Analyze the goodness of fit of each echo envelope at each scanning point on the O-ring;

[0070] All reflected pulse signals corresponding to each echo envelope of each scanning point on the O-ring constitute the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring;

[0071] Analyze the distance between the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring and the ultrasonic reflection sequence of the first echo envelope;

[0072] It should be noted that there are many methods for calculating distance. In this embodiment, DTW distance is used to measure the difference between each echo envelope and the first echo envelope. The implementer may also use other methods for calculating distance such as Euclidean distance and Manhattan distance, and this embodiment does not impose any special restrictions.

[0073] The calculation process of DTW distance and goodness of fit is a well-known technique, and the specific calculation process will not be described in detail.

[0074] Further, the envelope similarity of each echo envelope of each scanning point on the O-ring is the ratio of the goodness of fit of each echo envelope of each scanning point on the O-ring to the distance.

[0075] When the echo envelope is the echo envelope of the real inner ring surface, the fluctuation change of the echo envelope is closer to that of the first echo envelope, and the distance between the ultrasonic reflection sequences of the two envelopes is small. At the same time, if the echo envelope is less disturbed by the outside world, the curve of the echo envelope is smoother, so the larger the value of the goodness of fit is, the greater the envelope similarity is; on the contrary, if the echo envelope is introduced by environmental noise, the greater the difference in the fluctuation change between the echo envelope and the first echo envelope is, the greater the distance between the ultrasonic reflection sequences of the two envelopes is, the smaller the goodness of fit is, and the smaller the envelope similarity is.

[0076] S202: fundamental frequency deviation of each echo envelope at each scanning point on the O-ring.

[0077] In actual application, the use of ultrasonic wave to measure the size of O-rings is often affected by external noise and other factors, thus affecting the authenticity of the echo envelope detection. Therefore, according to the difference between the fundamental frequency of each echo envelope at each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, the fundamental frequency deviation of each echo envelope at each scanning point on the O-ring is determined to verify whether the echo signal is formed by the reflection of the ultrasonic pulse signal on the inner surface of the O-ring, specifically:

[0078] The fundamental frequency deviation of each echo envelope of each scan on the O-ring is the absolute value of the difference between the fundamental frequency of each echo envelope of each scan point on the O-ring and the frequency of the ultrasonic pulse signal.

[0079] If the echo envelope is the true inner ring surface echo envelope, the fundamental frequency corresponding to the echo envelope is slightly different from the frequency of the ultrasonic pulse signal of the transmitting crystal, and the fundamental frequency deviation of the echo envelope is smaller; on the contrary, if the echo envelope is clutter caused by other factors, the fundamental frequency corresponding to the echo envelope is significantly different from the frequency of the ultrasonic pulse signal of the transmitting crystal, and the fundamental frequency deviation of the echo envelope is larger.

[0080] S203: echo confidence of each echo envelope of each scanning point on the O-ring.

[0081] In order to further exclude the false envelope generated by external noise from measuring the size of the O-ring, the envelope confidence of each echo envelope at each scanning point on the O-ring is determined based on the envelope similarity and fundamental frequency deviation of each echo envelope at each scanning point on the O-ring, so as to reduce the situation where interference factors are misjudged as real echo signals. Specifically:

[0082] The expression of the echo confidence of each echo envelope at each scanning point on the O-ring is: In the formula, A i,j Indicates the echo confidence of the jth echo envelope at the i-th scanning point on the O-ring; B i,j represents the envelope similarity of the jth echo envelope at the i-th scanning point on the O-ring; C i,j It represents the fundamental frequency deviation of the jth echo envelope of the ith scanning point on the O-ring; γ is a preset constant greater than 0, wherein the value of γ is manually set. In this embodiment, the value of γ is 0.01 to prevent the denominator from being 0. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0083] If the echo envelope is caused by clutter or environmental noise, the waveform of the echo envelope is seriously disturbed by environmental noise due to the interference of external environmental factors. At this time, the goodness of fit of the echo envelope is small, and there is a large deviation from the waveform of the first echo envelope, so the envelope similarity is small. At the same time, since the echo envelope is a false envelope caused by environmental noise, the fundamental frequency of the echo envelope obtained is greatly different from the frequency of the transmitted pulse signal, the fundamental frequency deviation is large, and the echo confidence of the echo envelope is small.

[0084] Step S3: Determine the envelope evaluation factor of each echo envelope of each scanning point on the O-ring according to the time difference between each echo envelope of each scanning point on the O-ring and the echo envelopes of the same corresponding order in other scanning points in combination with the echo confidence.

[0085] In step S2, the echo confidence of each echo envelope of each scanning point on the O-ring is obtained according to the difference between the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, combined with the envelope similarity, thereby eliminating the possibility that the echo envelope of each scanning point on the O-ring is a false echo envelope caused by environmental noise, etc., which interferes with the real echo envelope.

[0086] However, due to the small curvature of the O-ring, the ultrasonic wave may encounter more curved edges during propagation, resulting in increased reflection and scattering. These reflected and scattered waves will arrive at the receiver together with the original signal, forming a multipath effect.

[0087] The echo envelope caused by the multipath effect is basically consistent with the first echo envelope in shape, and has a small frequency difference with the frequency of the ultrasonic pulse signal, which makes the echo confidence value caused by the multipath effect larger, which will interfere with the judgment of the real inner ring surface reflection pulse signal. Therefore, it is necessary to further analyze the reflection pulse signal of the scanning point, specifically:

[0088] S301: echo time difference of each echo envelope of each scanning point on the O-ring.

[0089] The multipath effect may interfere with the real echo signal, thus leading to misjudgment. Therefore, according to the time difference between each scanning point on the O-ring and the echo envelopes of the same order of other scanning points, the echo time difference of each echo envelope of each scanning point on the O-ring is determined to accurately identify and deal with the interference caused by the multipath effect, so as to more accurately evaluate the quality and integrity of the O-ring, specifically:

[0090] The expression for the echo time difference of each echo envelope at each scanning point on the O-ring is: In the formula, Represents the echo time difference of the jth echo envelope at the i-th scanning point on the O-ring; It represents the intersection-and-joint ratio of the i-th scanning point on the O-ring and the k-th scanning point on the j-th echo envelope corresponding time interval; N represents the number of all scanning points on the O-ring; γ is a preset constant greater than 0, wherein the value of γ is artificially set. In this embodiment, the value of γ is 0.01 to prevent the denominator from being 0. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0091] It should be noted that the intersection-and-union ratio is a well-known technique in mathematical calculations. The so-called intersection-and-union ratio is the ratio of the intersection of two sets to their union, and its specific calculation process will not be repeated here.

[0092] If the echo envelope is caused by the multipath effect, since different scanning points are affected by the multipath effect in different ways, the echo envelope of the multipath effect at the current scanning point may correspond to the interval position between each echo envelope in the reflected pulse signal of other scanning points, and the intersection and union of the time intervals of the current scanning point and other scanning points for the same order of envelopes is relatively small, and the echo time difference is large. On the contrary, if the echo envelope corresponds to the echo envelope caused by the inner ring surface, since the cross-sectional diameter of the O-ring is not much different, the intersection and union of the echo envelope at the current scanning point and the time intervals of the corresponding echo envelopes of the same order at other scanning points are relatively large, and the echo time difference is small.

[0093] S302: Envelope evaluation factor of each echo envelope of each scanning point on the O-ring.

[0094] Furthermore, in order to more accurately evaluate the authenticity and reliability of each echo envelope, the echo confidence and echo time difference of each echo envelope at each scanning point on the O-ring are combined to obtain the envelope evaluation factor of each echo envelope at each scanning point on the O-ring to reflect the quality and credibility of the echo envelope, specifically:

[0095] The envelope evaluation factor of each echo envelope of each scanning point on the O-ring is the ratio of the echo confidence of each echo envelope of each scanning point on the O-ring to the echo time difference.

[0096] If the echo envelope is the echo envelope formed by the real inner ring surface reflection pulse signal, the shape of the echo envelope is basically the same as the first echo envelope, so the echo confidence value is larger. At the same time, since the cross-sectional diameter of the O-ring will not differ too much, the intersection and combination of the time intervals corresponding to the echo envelope at different scanning points is relatively large, so the value of the echo time difference is small, and finally the envelope evaluation factor of the echo envelope is large; on the contrary, if the echo envelope is a false echo envelope caused by environmental noise, the shape of the false echo envelope is very different from the first echo envelope, and the echo confidence is smaller. At the same time, the intersection and combination of the time intervals corresponding to the redundant envelopes caused by multipath interference is relatively small, the echo time difference is larger, and the envelope evaluation factor is smaller.

[0097] Preferably, the schematic diagram of the envelope evaluation factor extraction process provided in the present application is as follows: Figure 5 shown.

[0098] Step S4: Based on the envelope evaluation factor of each echo envelope of each scanning point on the O-ring, combined with the time when each scanning point on the O-ring receives the first echo envelope and the speed of ultrasonic wave propagation in the O-ring, determine the cross-sectional diameter of each scanning point on the O-ring.

[0099] Except for the first echo envelope of each scanning point on the O-ring, the echo envelope corresponding to the maximum envelope evaluation factor of each scanning point on the O-ring is used as the inner ring echo envelope of each scanning point on the O-ring.

[0100] The ultrasonic flight time of each scanning point on the O-ring is the difference between the time when each scanning point on the O-ring receives the inner ring echo envelope and the time when the first echo envelope is received.

[0101] The propagation speed of ultrasonic waves in the O-ring is obtained through the material database, and the intercept diameter of each scanning point on the O-ring is obtained. The expression is: Where, d i represents the intercept diameter of the i-th scanning point on the O-ring; v represents the propagation speed of the ultrasonic wave in the O-ring; ToF i Represents the ultrasonic flight time of the i-th scanning point on the O-ring.

[0102] Step S5: measuring the size of the O-ring based on the maximum and minimum values ​​of the cross-sectional diameters of all scanning points on the O-ring.

[0103] According to step S4, the intercept diameter of each scanning point on the O-ring is obtained, thereby obtaining the tolerance range of the current O-ring. The specific process is:

[0104] The difference between the minimum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the lower limit of the tolerance range of the O-ring, and the difference between the maximum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the upper limit of the tolerance range of the O-ring.

[0105] According to the different uses of O-rings, the tolerance range of the O-ring is obtained according to the standard manual (the tolerance range is basically in the form of [±3]). For example, for O-rings used in hydraulics and pneumatics, refer to "GB / T 3452.1-2005" to obtain the corresponding tolerance range of the O-ring.

[0106] If the tolerance range of the O-ring is a subset of the tolerance range, the O-ring size meets the production standard requirements; otherwise, the O-ring production is unqualified and the generation parameters need to be adjusted.

[0107] At this point, the measurement of the O-ring size is completed based on the tolerance range and tolerance range of the O-ring.

[0108] Preferably, the schematic diagram of the O-ring size measurement process provided in the present application is as follows: Figure 6 shown.

[0109] Based on the same inventive concept as the above method, an embodiment of the present application also provides a high-precision size measurement system for O-rings, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned methods for high-precision size measurement of O-rings when executing the computer program.

[0110] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0111] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0112] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for measuring the size of an O-ring with high precision, characterized in that: The method comprises the following steps: Obtain all reflected pulse signals after the ultrasonic pulse signal is reflected from each scanning point on the O-ring, and extract the echo envelope of all reflected pulse signals from each scanning point on the O-ring by using the envelope detection method; Determine the envelope similarity of each echo envelope at each scanning point on the O-ring according to the smoothness of each echo envelope at each scanning point on the O-ring and the difference between each echo envelope and the reflected pulse signal in the first echo envelope; Obtaining the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal, and determining the echo confidence of each echo envelope of each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope of each scanning point on the O-ring and the frequency of the ultrasonic pulse signal and combining the envelope similarity; Determine the envelope evaluation factor of each echo envelope of each scanning point on the O-ring according to the time difference between each echo envelope of each scanning point on the O-ring and the echo envelopes of the same corresponding order in other scanning points, combined with the echo confidence; Based on the envelope evaluation factor of all echo envelopes of each scanning point on the O-ring, combined with the time and speed at which the first echo envelope is received at each scanning point, the intercept diameter of each scanning point on the O-ring is determined; The size of the O-ring is measured based on the maximum and minimum values ​​of the intercept diameters of all scanning points on the O-ring; The method for determining the echo confidence of each echo envelope of each scanning point on the O-ring is: Determine the fundamental frequency deviation of each echo envelope at each scanning point on the O-ring according to the difference between the fundamental frequency of each echo envelope at each scanning point on the O-ring and the frequency of the ultrasonic pulse signal; The expression of the echo confidence of each echo envelope at each scanning point on the O-ring is: In the formula, A i,j Indicates the echo confidence of the jth echo envelope at the i-th scanning point on the O-ring; B i,j represents the envelope similarity of the jth echo envelope at the i-th scanning point on the O-ring; C i,j Indicates the fundamental frequency deviation of the jth echo envelope at the i-th scanning point on the O-ring; γ is a preset constant greater than 0; The method for determining the envelope evaluation factor of each echo envelope at each scanning point on the O-ring is: Determine the echo time difference of each echo envelope of each scanning point on the O-ring according to the time difference between each echo envelope of each scanning point on the O-ring and the echo envelopes of the same corresponding order in other scanning points; The envelope evaluation factor of each echo envelope at each scanning point on the O-ring is the ratio of the echo confidence of each echo envelope at each scanning point on the O-ring to the echo time difference; The expression for the echo time difference of each echo envelope at each scanning point on the O-ring is: In the formula, Represents the echo time difference of the jth echo envelope at the i-th scanning point on the O-ring; represents the intersection-and-joint ratio of the i-th scanning point on the O-ring and the k-th scanning point on the j-th echo envelope corresponding time interval; N represents the number of all scanning points on the O-ring; γ is a preset constant greater than 0.

2. A method for high-precision measurement of the size of an O-ring as claimed in claim 1, characterized in that: The method for determining the envelope similarity of each echo envelope at each scanning point on the O-ring is: Analyze the goodness of fit of each echo envelope at each scanning point on the O-ring; All reflected pulse signals corresponding to each echo envelope of each scanning point on the O-ring constitute the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring; Analyze the distance between the ultrasonic reflection sequence of each echo envelope of each scanning point on the O-ring and the ultrasonic reflection sequence of the first echo envelope; The envelope similarity of each echo envelope of each scanning point on the O-ring is the ratio of the goodness of fit of each echo envelope of each scanning point on the O-ring to the distance.

3. A method for high-precision measurement of the size of an O-ring as claimed in claim 1, characterized in that: The fundamental frequency deviation of each echo envelope of each scan on the O-ring is the absolute value of the difference between the fundamental frequency of each echo envelope of each scan point on the O-ring and the frequency of the ultrasonic pulse signal.

4. A method for high-precision measurement of the size of an O-ring as claimed in claim 1, characterized in that: The method for determining the cross-sectional diameter of each scanning point on the O-ring is: Based on the envelope evaluation factor of all echo envelopes of each scanning point on the O-ring, combined with the time when the first echo envelope is received at each scanning point on the O-ring, the ultrasonic flight time of each scanning point on the O-ring is determined; Obtain the propagation speed of ultrasonic waves in the O-ring. The expression of the intercept diameter at each scanning point on the O-ring is: Where, d i represents the intercept diameter of the i-th scanning point on the O-ring; v represents the propagation speed of the ultrasonic wave in the O-ring; ToF i Represents the ultrasonic flight time of the i-th scanning point on the O-ring.

5. A method for measuring the size of an O-ring with high precision as claimed in claim 4, characterized in that: The method for determining the ultrasonic flight time of each scanning point on the O-ring is: Except for the first echo envelope of each scanning point on the O-ring, the echo envelope corresponding to the maximum envelope evaluation factor of each scanning point on the O-ring is used as the inner ring echo envelope of each scanning point on the O-ring; The ultrasonic flight time of each scanning point on the O-ring is the difference between the time when each scanning point on the O-ring receives the inner ring echo envelope and the time when the first echo envelope is received.

6. A method for high-precision measurement of the size of an O-ring as claimed in claim 1, characterized in that: The measuring of the size of the O-ring includes: The difference between the minimum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the lower limit of the tolerance range of the O-ring, and the difference between the maximum diameter of all scanning points on the O-ring and the mean diameter of all scanning points is used as the upper limit of the tolerance range of the O-ring; The tolerance range of the O-ring is preset. If the tolerance range of the O-ring is a subset of the tolerance range, the size of the O-ring is qualified, otherwise, the size of the O-ring is unqualified.

7. A high-precision measurement system for the size of an O-ring, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for high-precision measurement of the size of an O-ring as described in any one of claims 1-6 are implemented.

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