CN116296053A - Method and system for generating longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement - Google Patents
Method and system for generating longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement Download PDFInfo
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Abstract
The invention belongs to the technical field of ultrasonic bolt pretightening force measurement, and discloses a method and a system for generating a virtual calibration curve of a longitudinal wave in ultrasonic bolt pretightening force measurement, wherein the method for generating the virtual calibration curve of a single longitudinal wave in ultrasonic bolt pretightening force measurement comprises the following steps: inputting information of a bolt to be detected, and calculating an optimal shape factor and a material factor according to an ultrasonic bolt pretightening force detection principle model; calculating a detection coefficient by using the clamping length, and displaying the detection coefficient to a user in a virtual calibration curve mode; and measuring the ultrasonic bolt pretightening force of the bolt to be measured by using the detection coefficient and the corresponding virtual single longitudinal wave calibration curve. According to the method, the system and the equipment for testing the bolts of various specifications, grades, shapes and manufacturers, a single longitudinal wave virtual calibration curve method, a single longitudinal wave virtual calibration system and single longitudinal wave virtual calibration equipment in ultrasonic bolt pre-tightening force measurement are established, and the applicability of the single longitudinal wave virtual calibration curve method, the single longitudinal wave virtual calibration system and the single longitudinal wave virtual calibration equipment is evaluated through the experiments, so that the ultrasonic bolt pre-tightening force measurement equipment can output pre-tightening force with higher precision under the condition of avoiding calibration, and the single longitudinal wave virtual calibration curve method, the single longitudinal wave virtual calibration system and the single longitudinal wave virtual calibration equipment have certain engineering applicability.
Description
Technical Field
The invention belongs to the technical field of ultrasonic bolt pretightening force measurement, and particularly relates to a method, a system and equipment for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement.
Background
At present, the bolt is a transversely applied product in the industrial field, is the most widely applied structural connection form, and the pretightening force is the unique design and working index of the bolt. Studies have shown that failure of more than 80% of the bolts is due to insufficient pretension, so it is critical whether the bolt pretension is within design limits. However, due to the differences of the bolt fastening process, the individual torque coefficient or friction coefficient of the bolts, the actual working condition, the design condition and the like, larger deviation between the pretightening force of the bolts and the design margin can be caused, and the reliability and the safety of the product structure are reduced. Therefore, it is necessary to measure the bolt preload.
The main method for measuring the bolt pretightening force is an ultrasonic method and a strain method. At present, the ultrasonic method has the advantage of avoiding damaging the bolt structure, is widely applied in the fields of bolt fastening process verification and the like, and the ultrasonic detection method, specification and standard of the bolt pretightening force based on the acoustic elasticity theory are developed gradually.
The relation between the acoustic time difference and the bolt pretightening force is obtained on a universal testing machine or a twisting machine and is called a longitudinal wave calibration curve or a detection coefficient, and the calibration curve is a function of the material and the geometric shape of the bolt. In practical engineering projects, the bolts to be tested are tens, hundreds or even thousands, for the same specification of bolt connection, manufacturers and batches of the bolts can be different, the clamping length can also be changed frequently according to structural design, and the factors lead to a large number of bolt calibration tests, consume huge manpower and material resources, and are bottlenecks for the ultrasonic bolt pretightening force measurement technology and the wide application of products from laboratories to engineering sites.
Aiming at the acquisition problem of the calibration curve, a limited number of calibration curves are used as basic data, a virtual calibration curve is generated by extension deduction and generation aiming at specific bolting, and the basic data and a related algorithm for generating the calibration curve have higher practical significance in the range allowed by engineering precision.
Through the above analysis, the problems and defects existing in the prior art are as follows: the existing ultrasonic bolt pretightening force equipment is complicated in calibration, low in efficiency and long in time.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a method and a system for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement.
The invention is realized in such a way that a single longitudinal wave virtual calibration curve method in ultrasonic bolt pretightening force measurement comprises the following steps:
step one, inputting information of a bolt to be detected, and calculating an optimal shape factor and a material factor according to an ultrasonic bolt pretightening force detection principle model;
calculating a detection coefficient by using the clamping length, and displaying the detection coefficient to a user in a virtual calibration curve mode;
and thirdly, measuring the ultrasonic bolt pretightening force of the bolt to be tested by using the detection coefficient and the corresponding virtual single longitudinal wave calibration curve.
Further, the information of the bolt to be tested comprises clamping length and whether the diameter is changed.
Further, the ultrasonic bolt pretightening force detection principle model process comprises the following steps:
let the equivalent stress length of the bolt be l, adopt the ultrasonic excitation and receiving mode of spontaneous self-receiving, the relation of acoustic time difference deltat and stress sigma is:
wherein E is the Young's modulus of the bolt material; v l0 Is the velocity of sound of longitudinal waves in a zero stress state; k (K) l Is the acoustic elasticity coefficient of longitudinal wave;
the bolt pretension force F is:
wherein lambda is
A s Is the stress cross section area of the bolt;
further, the bolt material factor is:
further, the bolt pretightening force F is simplified as follows:
where λ is the form factor of the bolt and k is the detection coefficient.
Further, the form factor function is:
wherein lambda is c Is a form factor constant, h is the measured grip length.
Further, the detection coefficient k is:
further, the bolt to be tested is a bolt which has small diameter change and accords with national standards, and the calibration curve k is a calibration curve k under different clamping lengths 1 The method is obtained on a universal testing machine or a twisting machine, and the corresponding detection coefficient k is obtained by testing under different clamping lengths h, so that the material factor M and the shape factor constant lambda can be obtained through first-order linear fitting c And further obtaining the detection coefficient k under any clamping length h in practical application.
Another object of the present invention is to provide a single longitudinal wave virtual calibration curve system in ultrasonic bolt pre-tightening force measurement for implementing the single longitudinal wave virtual calibration curve method in ultrasonic bolt pre-tightening force measurement, the single longitudinal wave virtual calibration curve system in ultrasonic bolt pre-tightening force measurement includes:
the system comprises a sample acquisition module, a calibration test module, a database, a data acquisition module and a data acquisition module, wherein the sample acquisition module is used for acquiring and testing samples, the calibration test is carried out on a universal testing machine through bolt samples of various specifications, grades, factories and batches by different clamping lengths to obtain form factors and material factors, and the system stores the acquired form factors and material factors into the database;
the input module is used for processing the input information of the bolt to be detected, when the system is used, a user inputs various available information of the bolt to be detected, and the system can find out the closest shape factor and material factor according to the information input by the user; if the information input by the user is missing, the system can use the material factors of other manufacturers and optimize the material factors appropriately;
the system searches and calculates the optimal shape factor and material factor in the database according to the bolt information input by the user, automatically calculates the detection coefficient according to the clamping length input by the user, displays the detection coefficient to the user in the form of a virtual calibration curve, and uses the detection coefficient and the corresponding virtual single longitudinal wave calibration curve when the bolt to be tested is used for measuring the pretightening force of the ultrasonic bolt.
Another object of the present invention is to provide a computer device, the computer device including a memory and a processor, the memory storing a computer program, which when executed by the processor, causes the processor to execute the steps of the method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretension measurement, including:
the ultrasonic equipment lower computer is used for performing a calibration test through a limited number of bolt samples to obtain basic data of a longitudinal wave virtual calibration curve algorithm;
the upper computer is used for automatically generating a longitudinal wave virtual calibration curve of the bolt to be tested for inputting basic bolt information of the specification, grade and clamping length of the bolt to be tested, and calculating the pretightening force of the acoustic time difference transmitted back to the lower computer according to the longitudinal wave virtual calibration curve.
Further, after receiving a measurement instruction of an upper computer or a mobile phone in a first wired or wireless mode, the lower computer of the ultrasonic equipment uses a temperature probe and an ultrasonic probe for temperature compensation to measure the bolt to be measured.
Further, the lower computer of the ultrasonic equipment transmits electric excitation to the bolt to be detected through the ultrasonic probe to generate ultrasonic longitudinal waves with the same frequency as the excitation, the ultrasonic longitudinal waves propagate along the bolt from one end of the bolt to be detected, are received by the ultrasonic probe after being reflected by the other end of the bolt and generate electric signals, and the lower computer calculates the sound propagated in the bolt by the ultrasonic waves and compares the sound with the sound of the bolt under the condition of zero stress to obtain sound time difference; after the lower computer compensates the temperature of the acoustic time difference, the acoustic time difference is transmitted to an upper computer or a mobile phone in a second wired or wireless mode, software of the upper computer generates a longitudinal wave virtual calibration curve according to bolt information recorded by a user, and the longitudinal wave virtual calibration curve is used for calculating the bolt pretightening force and displaying the bolt pretightening force to a client and storing the bolt pretightening force.
Further, the apparatus further comprises: the cloud end updates the algorithm program from the cloud end through the Internet by the upper computer, and meanwhile, the calibration test data made by the equipment are uploaded to the cloud end and fed back to equipment manufacturers.
Further, the upper computer comprises a computer or a mobile phone.
In combination with the above technical solution and the technical problems to be solved, please analyze the following aspects to provide the following advantages and positive effects:
according to the invention, a limited number of longitudinal wave calibration curves are used as basic data, and for specific bolted connection, a longitudinal wave virtual calibration curve is epitaxially deduced and generated, so that the method is free from calibration within the allowable range of engineering precision and has higher practical significance.
The bolt pretightening force measurement is carried out on a bolt with a certain specification, and the following influencing parameters exist: the specification, grade, manufacturer, batch, clamping thickness and shape of the bolts are all required to be calibrated on a universal testing machine to form a specific detection coefficient; and an influencing parameter is changed, such as: batch, typically calibration, must be re-performed, which results in significant effort and cost expended in calibrating the ultrasonic bolt pretension measurement. The data are acquired on the universal testing machine through the limited sample bolts, and the influence parameters are converted into the material factors and the shape factors in an algorithm mode, so that the cost caused by recalibration when any influence parameter changes can be avoided, and the bolt pretightening force measurement work is more efficient.
The invention greatly reduces the calibration work of ultrasonic bolt pretightening force measurement. The ultrasonic bolt pretightening force measuring equipment manufacturer uses limited samples, tests the samples on a universal testing machine, and converts influence factors of various bolt calibration into material factors and shape factors through an algorithm. In actual use, a user only needs to input the specification, grade, manufacturer, batch and clamping thickness of the bolt to be tested, and the ultrasonic bolt pre-tightening force measuring device with the longitudinal wave virtual calibration curve can automatically generate a calibration curve of sound time difference and pre-tightening force, so that the user can directly use the longitudinal wave virtual calibration curve to measure the bolt pre-tightening force of the bolt to be tested. Meanwhile, when the equipment is actually used, the ultrasonic bolt pretightening force measurement equipment manufacturer and the user can continuously optimize the precision of the longitudinal wave virtual calibration curve in the equipment by the calibration data accumulated on the universal testing machine or the torsion drawing machine, and all the equipment of the manufacturer is upgraded into a product with the longitudinal wave virtual calibration curve function in the form of calibration data sharing and software updating.
The expected benefits and commercial values after the technical scheme of the invention is converted are as follows: the ultrasonic bolt pretightening force measuring technology and equipment are used, and a calibration test is required to be carried out on the bolt to be tested on a universal testing machine, so that a corresponding calibration curve is generated. The test cost and the time cost of a user are greatly increased, and the virtual calibration curve can solve the problem and reduce the cost of ultrasonic bolt pretightening force measurement to the greatest extent.
The technical scheme of the invention fills the technical blank in the domestic and foreign industries: at present, all manufacturers of ultrasonic bolt pretightening force measuring equipment in the world do not provide the realization of the algorithm and the system for automatically generating the virtual calibration curve, and the realization of the algorithm and the system for automatically generating the virtual calibration curve fills the technical blank at home and abroad.
Whether the technical scheme of the invention solves the technical problems that people want to solve all the time but fail to obtain success all the time is solved: as equipment manufacturers for measuring the pretightening force of the ultrasonic bolt, complaints of users on the bolt to be measured, which are required to be calibrated, are not absolute, and the algorithm and the system for automatically generating the virtual calibration curve realize the aim of solving the biggest pain point of the users when using the pretightening force measuring equipment of the ultrasonic bolt.
Drawings
FIG. 1 is a flow chart of a method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement provided by the embodiment of the invention;
FIG. 2 is a flow chart of a single longitudinal wave virtual calibration curve system in ultrasonic bolt pretightening force measurement provided by the embodiment of the invention;
FIG. 3 is a schematic diagram of a single longitudinal wave virtual calibration curve device in ultrasonic bolt pretightening force measurement according to an embodiment of the present invention;
fig. 4 is a fitting result of linearity of an application case provided by an embodiment of the present invention;
FIG. 5 is a schematic view of a linear relationship fit between clamping distance and 1/k of a slender waist bolt according to an embodiment of the present invention; a) Manufacturer A M36 x 410mm clamping distance h is fitted to a linear relationship of 1/k; b) Manufacturer B12.9 class M36.625 mm clamping distance h is fitted to a linear relationship of 1/k; c) C manufacturer 10.9 grade M36 is fitted with a linear relation of 235mm clamping distance h and 1/k; d) Manufacturer A10.9 class M42 is fitted with a linear relationship of 1/k with a clamping distance h of 180 mm; e) D manufacturer 10.9 grade M36 is fitted with a linear relation of clamping distance h of 360mm and 1/k; f) E manufacturer 10.9 class M42 x 510mm clamping distance h is fitted to a linear relationship of 1/k; g) E manufacturer 10.9 grade M30 x 240mm clamping distance h is fitted with a linear relationship of 1/k; h) F manufacturer 10.9 grade M30 is fitted with a linear relation of clamping distance h of 410mm and 1/k; i) G manufacturer 10.9 grade M20 is fitted with a linear relation of clamping distance h of 170mm and 1/k; j) H manufacturer 8.8 grade M20 is fitted with a linear relation of 130mm clamping distance H and 1/k; k) Fitting the linear relation between the clamping distance h of 8.8-grade M12 x 60mm of the manufacturer I and 1/k; l) fitting the linear relation between the clamping distance h of 8.8-grade M12 of I manufacturer and 1/k;
FIG. 6 is a schematic view 2 of a linear relationship fit between clamping distance and 1/k of a slender waist bolt according to an embodiment of the present invention; a) D manufacturer 10.9 grade M36 x 610mm clamping distance h is fitted to a linear relationship of 1/k; b) I manufacturer 10.9 grade M36 x 610mm, 7201 batch clamping distance h is fitted to a linear relationship of 1/k; c) I manufacturer 10.9 grade M36 x 610mm, 7202 batch clamping distance h is fitted to a linear relationship of 1/k; d) Manufacturer B, 10.9 grade M36, is fitted with a linear relationship of 700mm clamping distance h and 1/k; e) J manufacturer 10.9 grade M36 x 815mm clamping distance h is fitted to a linear relationship of 1/k;
in the figure: 1. an ultrasonic equipment lower computer; 2. a temperature probe; 4. the upper computer or the mobile phone; 5. and (3) cloud end. 6. A first wired or wireless; 7. electrically exciting; 8. an electrical signal; 9. a second wired or wireless; 10. an ultrasonic probe.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In order to fully understand how the invention may be embodied by those skilled in the art, this section is an illustrative embodiment in which the claims are presented for purposes of illustration.
According to the theory of acoustic elasticity, when an isotropic solid material is subjected to stress in one direction, the speed of sound of ultrasonic longitudinal waves propagating along the stress direction can be deduced as:
v Lσ ＝v L0 (1-K L σ)
wherein: v Lσ Representing stress, and the velocity of sound of longitudinal wave when the stress is sigma; v L0 Is the velocity of sound of longitudinal waves in a zero stress state; k (K) L Is the acoustic elasticity coefficient of the longitudinal wave. Wherein tensile stress is defined as positive and compressive stress is defined as negative.
As shown in fig. 1, the method for measuring a single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force according to the embodiment of the invention includes:
s101, inputting information of a bolt to be detected, and calculating an optimal shape factor and a material factor according to an ultrasonic bolt pretightening force detection principle model;
s102, calculating a detection coefficient by using the clamping length, and displaying the detection coefficient to a user in a virtual calibration curve mode;
s103, measuring the ultrasonic bolt pretightening force of the bolt to be tested by using the detection coefficient and the corresponding virtual single longitudinal wave calibration curve.
Further, the information of the bolt to be tested comprises clamping length and whether the diameter is changed.
Further, the ultrasonic bolt pretightening force detection principle model process comprises the following steps:
let the equivalent stress length of the bolt be l, adopt the ultrasonic excitation and receiving mode of spontaneous self-receiving, the relation of acoustic time difference deltat and stress sigma is:
wherein E is the Young's modulus of the bolt material; v l0 Is the velocity of sound of longitudinal waves in a zero stress state; k (K) l Is the acoustic elasticity coefficient of longitudinal wave;
the bolt pretension force F is:
wherein lambda is
A s Is the stress cross section area of the bolt;
further, the bolt material factor is:
further, the bolt pretightening force F is simplified as follows:
where λ is the form factor of the bolt and k is the detection coefficient.
Further, the form factor function is:
wherein lambda is c Is a form factor constant, h is the measured grip length.
Further, the detection coefficient k is:
further, if the bolt to be tested is a non-reducing bolt, the calibration curve k is obtained under different clamping lengths 1 The method is obtained on a universal testing machine or a twisting machine, and then the material factor M and the shape factor constant can be obtained through first-order linear fitting, and further the arbitrary clamping length h can be obtained in practical application Detecting A coefficient k.
The bolt to be tested is a reducing bolt A s As a function of the clamping length h, the functional relationship between h and k is obtained by a high-order fitting method.
As shown in fig. 2, the embodiment of the present invention further provides a single longitudinal wave virtual calibration curve system in ultrasonic bolt pretightening force measurement, where the single longitudinal wave virtual calibration curve system in ultrasonic bolt pretightening force measurement includes:
the system comprises a sample acquisition module, a calibration test module, a database, a data acquisition module and a data acquisition module, wherein the sample acquisition module is used for acquiring and testing samples, the calibration test is carried out on a universal testing machine through bolt samples of various specifications, grades, factories and batches by different clamping lengths to obtain form factors and material factors, and the system stores the acquired form factors and material factors into the database;
the input module is used for processing the input information of the bolt to be detected, when the system is used, a user inputs various available information of the bolt to be detected, and the system can find out the closest shape factor and material factor according to the information input by the user; if the information input by the user is missing, the system can use the material factors of other manufacturers and optimize the material factors appropriately;
the system searches and calculates the optimal shape factor and material factor in the database according to the bolt information input by the user, automatically calculates the detection coefficient according to the clamping length input by the user, displays the detection coefficient to the user in the form of a virtual calibration curve, and uses the detection coefficient and the corresponding virtual single longitudinal wave calibration curve when the bolt to be tested is used for measuring the pretightening force of the ultrasonic bolt.
As shown in fig. 3, the embodiment of the present invention further provides a single longitudinal wave virtual calibration curve device in ultrasonic bolt pretightening force measurement, where the device includes:
the ultrasonic equipment lower computer is used for performing a calibration test through a limited number of bolt samples to obtain basic data of a longitudinal wave virtual calibration curve algorithm;
the upper computer is used for automatically generating a longitudinal wave virtual calibration curve of the bolt to be tested for inputting basic bolt information of the specification, grade and clamping length of the bolt to be tested, and calculating the pretightening force of the acoustic time difference transmitted back to the lower computer according to the longitudinal wave virtual calibration curve.
Further, after receiving a measurement instruction of an upper computer or a mobile phone in a first wired or wireless mode, the lower computer of the ultrasonic equipment uses a temperature probe and an ultrasonic probe for temperature compensation to measure the bolt to be measured.
Further, the lower computer of the ultrasonic equipment transmits electric excitation to the bolt to be detected through the ultrasonic probe to generate ultrasonic longitudinal waves with the same frequency as the excitation, the ultrasonic longitudinal waves propagate along the bolt from one end of the bolt to be detected, are received by the ultrasonic probe after being reflected by the other end of the bolt and generate electric signals, and the lower computer calculates the sound propagated in the bolt by the ultrasonic waves and compares the sound with the sound of the bolt under the condition of zero stress to obtain sound time difference; after the lower computer compensates the temperature of the acoustic time difference, the acoustic time difference is transmitted to an upper computer or a mobile phone in a second wired or wireless mode, software of the upper computer generates a longitudinal wave virtual calibration curve according to bolt information recorded by a user, and the longitudinal wave virtual calibration curve is used for calculating the bolt pretightening force and displaying the bolt pretightening force to a client and storing the bolt pretightening force.
Further, the apparatus further comprises: the cloud end updates the algorithm program from the cloud end through the Internet by the upper computer, and meanwhile, the calibration test data made by the equipment are uploaded to the cloud end and fed back to equipment manufacturers.
Further, the testing machine is replaced by a twisting machine.
Further, the upper computer comprises a computer or a mobile phone.
In order to prove the inventive and technical value of the technical solution of the present invention, this section is an application example on specific products or related technologies of the claim technical solution.
The ultrasonic bolt pretightening force measuring device with single longitudinal wave virtual calibration curve generation provided by the embodiment of the invention comprises:
the method is used for constructing a bolt pretightening force ultrasonic longitudinal wave detection model based on a material factor and a shape factor;
the ultrasonic bolt pretightening force measuring device with the single longitudinal wave virtual calibration curve generation function is further provided with a lower computer, and is used for measuring ultrasonic longitudinal waves when sound propagates along the bolt and then compensating the sound when the measured temperature is used.
Example 1:
according to the ultrasonic bolt pretightening force measuring device with the longitudinal wave virtual calibration curve generation, calibration tests are carried out on a universal testing machine through a limited number of bolt samples, and basic data of a longitudinal wave virtual calibration curve algorithm module are obtained. When a user uses the ultrasonic equipment, the ultrasonic equipment can automatically generate a longitudinal wave virtual calibration curve of the bolt to be tested only by inputting basic bolt information such as the specification, the grade, the clamping length and the like of the bolt to be tested.
The ultrasonic bolt pretightening force measuring equipment with the longitudinal wave virtual calibration curve generation function is further provided with an upper computer, after the user inputs related bolt information, the longitudinal wave detection model is used for automatically generating a virtual calibration curve, and pretightening force calculation is carried out on acoustic time difference transmitted back to the lower computer according to the longitudinal wave virtual calibration curve.
In fig. 3, an ultrasonic device lower computer 1 with an ultrasonic bolt pretightening force measurement device generated by a single longitudinal wave virtual calibration curve provided by the embodiment of the invention measures a bolt 2 to be measured by using a temperature probe 2 and an ultrasonic probe 10 with temperature compensation after receiving a measurement instruction of an upper computer or a mobile phone 4 in a first wired or wireless mode 6.
During measurement, the ultrasonic equipment lower computer 1 emits electric excitation 7 to the bolt 2 through the ultrasonic probe 10 to generate ultrasonic longitudinal waves with the same frequency as the excitation, the ultrasonic longitudinal waves propagate along the bolt from one end of the bolt 2, are received by the ultrasonic probe 10 after being reflected by the other end of the bolt, and generate an electric signal 8, and when the ultrasonic equipment lower computer 1 calculates the sound of the ultrasonic waves propagating in the bolt, the sound is compared with the sound of the bolt under the condition of zero stress, so that the sound time difference is obtained; after the temperature compensation is carried out on the acoustic time difference, the ultrasonic equipment lower computer 1 transmits the acoustic time difference to the upper computer or the mobile phone 4 in a second wired or wireless mode 9, software of the upper computer 4 generates a longitudinal wave virtual calibration curve according to bolt information input by a user, calculates bolt pretightening force, and displays the bolt pretightening force to a client and stores the bolt pretightening force. The virtual longitudinal wave calibration curve algorithm updated by the ultrasonic equipment manufacturer can be deployed at the cloud end, the user upper computer can update the algorithm program from the cloud end 5 through the Internet, and meanwhile, calibration test data made by the ultrasonic equipment can be uploaded to the cloud end 5 and fed back to the equipment manufacturer so as to optimize a longitudinal wave detection model for generating a longitudinal wave virtual calibration curve, so that the longitudinal wave detection model is more accurate.
The embodiment of the invention has a great advantage in the research and development or use process, and has the following description in combination with data, charts and the like of the test process.
The embodiment of the invention expands factor analysis for influencing material factors and shape factors, and comprises the following steps:
the influence factors of the ultrasonic single longitudinal wave bolt pretightening force measurement calibration curve or the detection coefficient k can be decomposed into material factors and shape factors. Wherein the form factor is canonical and controllable in practical application, namely: different bolt manufacturers have strict requirements on the design values of the clamping distances of the bolts with the same specification in terms of the overall dimension and the structural designer. As for the material factors, the requirements of the national standard or industry standard of the fastener on the bolt materials and the heat treatment mode have certain range margins, and the requirements are self-mastered by bolt manufacturers, so the material factors are main influencing factors. For bolts of the same specification and the same grade, the influence factors of the material factor M can be summarized as follows:
bolt manufacturer: the differences of the material factors with the same specification and grade of different bolt manufacturers;
bolt batch: differences in material factors of the same specification, same grade but different batches of the same bolt manufacturer.
Test 1:
1. since the shape factor lambda is independent of the material factor M, it was verified experimentally.
Shape factor: for bolts of the same bolt manufacturer and the same batch, acquiring a single longitudinal wave and longitudinal wave ultrasonic bolt pretightening force measurement detection coefficient k, a clamping length h and an effective sectional area A of the bolt s The relation between the two is used for carrying out error analysis;
shape factor: for variable diameter bolts of the same bolt manufacturer and the same batch, acquiring a high-order fitting relation between a single longitudinal wave ultrasonic bolt pretightening force measurement detection coefficient k, a clamping length h and an effective sectional area of the variable diameter bolt, and performing error analysis;
material factor: obtaining a material factor M irrelevant to a shape factor for bolts of the same specification and the same grade but different batches of bolts of the same bolt manufacturer, and performing error analysis;
material factor: obtaining a material factor M for bolts of the same specification and the same grade of bolts of the same bolt manufacturer, and performing error analysis;
material factor: obtaining a material factor M for bolts of different bolt manufacturers and the same specification and class, and performing error analysis;
material factor: and obtaining a material factor M for bolts of different bolt manufacturers and different specifications but same class, and performing error analysis.
The above experimental purposes can be summarized in Table 1.
TABLE 1
The test purposes of 3-6 above were mainly carried out separately from the application, but the essence was to verify the dispersion of the material factor M under different conditions.
FIG. 4 shows an M36 bolt of 625mm length from a manufacturer. In fig. 4, the x-axis is the clamping length h (unit mm), the y-axis is 1/k, and the linearity can reach 0.9996 by performing first-order linear fitting through 3 points of the clamping length h as shown by the broken line in fig. 4.
2. Experimental apparatus and conditions
The experiment adopts a bolt stretcher of a fastener authentication center of a space standardization institute, and the main indexes are as follows: measuring range: 500KN; precision: 0.5%.
3. Experiment objects, processes and ultrasonic bolt pretightening force measuring equipment select bolts of a plurality of specifications M20 to M36 and different manufacturers for experimental verification. The experimental process is as follows: 1) Determining 1 clamping length, and placing an ultrasonic probe on the end face of a bolt to be tested; step-by-step loading is carried out on the steel wire rope by using a bolt stretcher, and calibration is carried out on the steel wire rope by using an ultrasonic bolt pretightening force measuring instrument; 2) The clamping length was changed and the calibration experiment described in 1) was repeated.
4. Experimental data can be classified into standard bolts and slender bolts according to the shape of bolts to be calibrated. Wherein the standard bolt meets national standards, namely: the diameter of the screw rod is not changed; the thin waist bolt is a bolt product designed by a host manufacturer according to the self demand, namely: the diameter of the screw rod can be changed, and the two ends are thick and the middle is thin. The experimental data of the standard bolts are shown in table 2, and the experimental data of the slender bolts are shown in table 3.
Table 2 calibration test data for standard bolts
Table 3 calibration experimental data for slender waist bolts
5 data analysis and precision assessment
5.1 data analysis and precision assessment of form factor verification experiments
From equation 8, it is shown that the form factor λ is represented by λ c And lambda is s Composition lambda c And lambda is s Is an important indicator of the suitability of the form factor lambda. According to the experimental data, when the ratio is smaller than 0.2, the linearity (R square value) of 1/k and the clamping distance h is larger than 0.99; above 1, the use of the shape factor λ is not recommended.
5.2 data analysis and precision assessment of Material factor verification test
From the experimental data of tables 1 and 2 and fig. 5, the following conclusions can be drawn: the material factor M is irrelevant to the strength grade of the bolt, and is only related to the elastic modulus of the metallurgical material, while the elastic modulus of bolts with different grades is basically consistent; the material factor M is independent of bolt manufacturers, batches and specifications, is only related to metallurgical materials, and the degree of dispersion is mainly determined by the difference of the elastic modulus of the metallurgical materials used by each bolt manufacturer.
For lambda in the form factor c And lambda is s Ratio r of (2)<Standard bolts of 0.1, with material factors M having maximum and minimum values of 0.1724 and 0.1459, respectively, and an average value of approximately 0.16, would have an error of approximately + -8% if the material factor average was used indiscriminately, regardless of manufacturer, lot, class, etc. For the slim bolt, the maximum and minimum values of the material factor M are 0.1975 and 0.1677, respectively, and the average value is approximately 0.18, and if the average value of the material factor M is used indiscriminately, an error of approximately + -8% is brought. The measuring precision has wide application significance in practical engineering application, and can meet the requirement of measuring precision of pretightening force of most field bolts. For lambda in the form factor c And lambda is s The ratio r of the bolts is larger than or equal to 1, and the material factor M is not recommended.
In practical application, after considering manufacturer, bolt grade and specification information of the bolt to be measured, measurement accuracy is greatly improved, for example: 1) For an M36 standard bolt of 10.9 grade or 12.9 grade, the maximum value and the minimum value of the material factor are 0.1677 and 0.155 respectively, the average value is 0.161, the error range is only +/-3.5%, and the measuring error range is very close to the error range of +/-3% of the ultrasonic bolt pretightening force measurement; 2) For the thin waist bolts with the same specification in two batches of the same manufacturer I, the material factors of the two batches are 0.1677 and 0.1775 respectively, the average value is 0.1726, and the error range is +/-3%.
From experimental data and accuracy analysis, the following preliminary conclusions can be drawn for the bolts of M12 to M42: shape factor: the shape factor lambda is defined by lambda c And lambda is s Composition lambda c And lambda is s Ratio r of (2)<At 0.1, the shape factor λ can be used indifferently; when r is 0.1 to less than or equal to r<At 1, the shape factor λ is used with care; when r.gtoreq.1, the use of the shape factor lambda is not recommended. Material factor: lambda when the shape factor lambda is lambda c And lambda is s Ratio r of (2)<At 0.1, the material factor M can be used indiscriminately, and a measurement error of + -8% exists; after considering other bolt information, such as: manufacturer, specification, grade, measurement error is + -3%; when r is 0.1 to less than or equal to r<1, the material factor M is carefully used; when r.gtoreq.1, the use of the material factor M is not recommended.
It should be noted that the embodiments of the present invention can be realized in hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or special purpose design hardware. Those of ordinary skill in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such as provided on a carrier medium such as a magnetic disk, CD or DVD-ROM, a programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device of the present invention and its modules may be implemented by hardware circuitry, such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., as well as software executed by various types of processors, or by a combination of the above hardware circuitry and software, such as firmware.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention will be apparent to those skilled in the art within the scope of the present invention.
Claims (10)
1. The method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement is characterized by comprising the following steps of:
step one, inputting information of a bolt to be detected, and calculating an optimal shape factor and a material factor according to an ultrasonic bolt pretightening force detection principle model;
calculating a detection coefficient by using the clamping length, and displaying the detection coefficient to a user in a virtual calibration curve mode;
and thirdly, measuring the ultrasonic bolt pretightening force of the bolt to be tested by using the detection coefficient and the corresponding virtual single longitudinal wave calibration curve.
2. The method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement according to claim 1, wherein the information of the bolt to be measured comprises clamping length and whether diameter is changed;
the ultrasonic bolt pretightening force detection principle model process comprises the following steps:
let the equivalent stress length of the bolt be l, adopt the ultrasonic excitation and receiving mode of spontaneous self-receiving, the relation of acoustic time difference deltat and stress sigma is:
wherein E is the Young's modulus of the bolt material; v l0 Is the velocity of sound of longitudinal waves in a zero stress state; k (K) l Is the acoustic elasticity coefficient of longitudinal wave;
the bolt pretension force F is:
wherein lambda is
A s Is the stress cross section area of the bolt;
the bolt material factor is:
3. the method for single longitudinal wave virtual calibration curve in ultrasonic bolt pre-tightening force measurement according to claim 1, wherein the bolt pre-tightening force F is simplified as follows:
wherein lambda is the shape factor of the bolt, and k is the detection coefficient;
the form factor function is:
wherein lambda is c Is a form factor constant, h is the measured grip length.
The above formula can also be summarized as:
λ＝λ s +λ c
in the middle of
The shape factor variable is a variable of the shape factor along with the clamping length and is called a shape factor variable; lambda (lambda) c Is a form factor constant.
4. The method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement according to claim 1, wherein the detection coefficient k is:
5. the method for single longitudinal wave virtual calibration curve in ultrasonic bolt pretightening force measurement according to claim 1, wherein the bolt to be measured is a non-reducing bolt, and the calibration curve k under different clamping lengths is the same 1 The method is obtained on a universal testing machine or a twisting machine, and then the material factor M and the shape factor constant can be obtained through first-order linear fitting, and further the arbitrary clamping length h can be obtained in practical application Detecting A coefficient k;
the bolt to be tested is a reducing bolt A s As a function of the clamping length h, the functional relationship between h and k is obtained by a high-order fitting method.
6. An ultrasonic bolt pretension measurement single longitudinal wave virtual calibration curve system implementing the ultrasonic bolt pretension measurement single longitudinal wave virtual calibration curve method according to any one of claims 1 to 5, characterized in that the ultrasonic bolt pretension measurement single longitudinal wave virtual calibration curve system includes:
the system comprises a sample acquisition module, a calibration test module, a database, a data acquisition module and a data acquisition module, wherein the sample acquisition module is used for acquiring and testing samples, the calibration test is carried out on a universal testing machine through bolt samples of various specifications, grades, factories and batches by different clamping lengths to obtain form factors and material factors, and the system stores the acquired form factors and material factors into the database;
the input module is used for processing the input information of the bolt to be detected, when the system is used, a user inputs various available information of the bolt to be detected, and the system can find out the closest shape factor and material factor according to the information input by the user; if the information input by the user is missing, the system can use the material factors of other manufacturers and optimize the material factors appropriately;
the system searches and calculates the optimal shape factor and material factor in the database according to the bolt information input by the user, automatically calculates the detection coefficient according to the clamping length input by the user, displays the detection coefficient to the user in the form of a virtual calibration curve, and uses the detection coefficient and the corresponding virtual single longitudinal wave calibration curve when the bolt to be tested is used for measuring the pretightening force of the ultrasonic bolt.
7. A single longitudinal wave virtual calibration curve apparatus for performing the method of any one of claims 1-5 in an ultrasonic bolt pretension measurement, comprising:
the ultrasonic equipment lower computer is used for performing a calibration test through a limited number of bolt samples to obtain basic data of a longitudinal wave virtual calibration curve algorithm;
the upper computer is used for automatically generating a longitudinal wave virtual calibration curve of the bolt to be tested for inputting basic bolt information of the specification, grade and clamping length of the bolt to be tested, and calculating the pretightening force of the acoustic time difference transmitted back to the lower computer according to the longitudinal wave virtual calibration curve.
8. The single longitudinal wave virtual calibration curve device in ultrasonic bolt pretightening force measurement according to claim 7, wherein the ultrasonic device lower computer uses a temperature probe and an ultrasonic probe of temperature compensation to measure the bolt to be measured after receiving a measurement instruction of an upper computer or a mobile phone in a first wired or wireless mode.
9. The single longitudinal wave virtual calibration curve equipment in ultrasonic bolt pretightening force measurement according to claim 7, wherein the ultrasonic equipment lower computer transmits electric excitation to the bolt to be measured through the ultrasonic probe to generate ultrasonic longitudinal waves with the same frequency as the excitation, the ultrasonic longitudinal waves propagate along the bolt from one end of the bolt to be measured, are received by the ultrasonic probe after being reflected by the other end of the bolt and generate electric signals, and the lower computer calculates the acoustic time difference when the ultrasonic waves propagate in the bolt and compares the acoustic time difference with the acoustic time of the bolt under the condition of zero stress; after the lower computer compensates the temperature of the acoustic time difference, the acoustic time difference is transmitted to an upper computer or a mobile phone in a second wired or wireless mode, software of the upper computer generates a longitudinal wave virtual calibration curve according to bolt information recorded by a user, and the longitudinal wave virtual calibration curve is used for calculating the bolt pretightening force and displaying the bolt pretightening force to a client and storing the bolt pretightening force.
10. The single longitudinal wave virtual calibration curve apparatus in ultrasonic bolt pretension measurement of claim 7, wherein the apparatus further comprises: the cloud end, the upper computer updates the algorithm program from the cloud end through the Internet, and meanwhile, the calibration test data made by the equipment are uploaded to the cloud end and fed back to equipment manufacturers;
the testing machine is replaced by a twisting machine;
the upper computer comprises a computer or a mobile phone.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117168676A (en) * | 2023-11-03 | 2023-12-05 | 广州市市政工程试验检测有限公司 | Method and device for detecting screw shaft force by ultrasonic wave |
| CN117168676B (en) * | 2023-11-03 | 2024-02-02 | 广州市市政工程试验检测有限公司 | Method and device for detecting screw shaft force by ultrasonic wave |
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