CN113916477B - Anti-loosening performance test and evaluation method for bolt connection pair - Google Patents
Anti-loosening performance test and evaluation method for bolt connection pair Download PDFInfo
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- CN113916477B CN113916477B CN202111161819.2A CN202111161819A CN113916477B CN 113916477 B CN113916477 B CN 113916477B CN 202111161819 A CN202111161819 A CN 202111161819A CN 113916477 B CN113916477 B CN 113916477B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
- G01M7/025—Measuring arrangements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/08—Shock-testing
Abstract
The application relates to the technical field of mechanical assembly, in particular to a method for testing and evaluating anti-loosening performance of a bolt connection pair. The anti-loosening performance test and evaluation method provided by the application comprises the following steps: tightening the calibration test bolt according to different axial clamping forces, measuring the axial elongation of the calibration test bolt after tightening by using measuring equipment, and establishing a corresponding relation between the axial clamping force and the elongation of the bolt; inputting the target value of the axial clamping force in the impact vibration test into the corresponding relation between the axial clamping force and the elongation of the bolt to obtain the elongation monitoring target value of the detected bolt; respectively screwing a plurality of bolts to be tested to an elongation monitoring target value to perform an impact vibration test; after the impact vibration test is finished, if all the tested bolts are loosened, determining the vibration resistance and the loose resistance according to the actual vibration cycle; if the unreleased tested bolt exists, calculating the clamping force retention rate of the unreleased tested bolt, and determining the anti-vibration and anti-loosening performance according to the clamping force retention rate.
Description
Technical Field
The application relates to the technical field of mechanical assembly, in particular to a method for testing and evaluating anti-loosening performance of a bolt connection pair.
Background
The assembly connection of automobiles and various mechanical devices mainly adopts a threaded fastener connection mode, and the threaded fastener connection is mostly a bolt (screw) fastening connection, in particular a bolt (screw) -nut connection pair. The bolt (screw) -nut connection mode has lower structural requirement on the connected piece, and can realize connection only by arranging a through hole on the connected piece, and the through hole has simple structure, low requirement on processing precision, convenient processing and low processing cost. The most common failure mode of the bolt during service after assembly is loosening of a fastener, the loosening can lead to loss of the auxiliary clamping force of the threaded connection and failure of the connection, and running safety or operation of mechanical equipment can be endangered in severe cases. Therefore, the looseness prevention performance of the bolt connection pair is the most important evaluation index in the service performance of the bolt.
In order to improve the anti-loosening performance of the bolt-nut connection pair, various types of bolts, nuts and gaskets with anti-loosening functions are developed and applied at present, but how to test and evaluate the anti-loosening performance of the bolt-nut connection pair in different types fairly and accurately is a problem which needs to be solved in the industry all the time.
The most common method for testing the anti-loosening performance of the bolt-nut connecting pair at present is a bolt connecting pair impact vibration test, and the adopted test device consists of a vibration table, a test fixture and a tested bolt-nut connecting pair. However, the test device has no bolt clamping force monitoring function, the tested bolt-nut can only be screwed in the fixture chute according to the target torque control, the numerical value of the connecting auxiliary clamping force cannot be directly obtained, and the size and the holding capacity of the bolt assembly clamping force are the most critical indexes for determining the anti-loosening performance of the bolt. The existing test device also has no bolt tightening axial force monitoring and measuring function. For various types of bolt, nut and washer connection pairs with the same thread specification and strength grade, the same tightening torque can only be used for controlling tightening during the test. It is known that the friction coefficient of the connection pairs (anti-loose washer, lock nut and common bolt nut) with different surface treatments and different friction forms is large, and the axial clamping force obtained by the bolt connection pairs with different forms after the same target torque is screwed up is multiple different. Impact vibration tests under conditions of excessively different bolt clamping forces can seriously affect test results and evaluation thereof.
Based on the analysis, it is necessary to provide a test and evaluation method capable of controlling the anti-loosening performance of the test bolt under the same clamping force level after the test bolt is tightened.
Disclosure of Invention
The embodiment of the application provides a method for testing and evaluating anti-loosening performance of a bolt connection pair, which aims to solve the problem that the existing bolt connection pair with the same strength grade and thread specification in the related art cannot conduct anti-loosening performance test under the same axial clamping force level.
In a first aspect, the application provides a method for evaluating anti-loosening performance of a bolt connection pair, comprising the following steps:
s101, on a bolt tightening performance testing machine, tightening calibration test bolts according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using measuring equipment, and establishing a corresponding relation between the axial clamping force and the axial elongation of the bolts according to the axial clamping force and the axial elongation of the calibration test bolts;
step S102, inputting an axial clamping force target value of a detected bolt in an impact vibration test into a corresponding relation between the axial clamping force and the elongation of the bolt to obtain an elongation monitoring target value of the detected bolt;
step S103, measuring the original lengths of a plurality of bolts to be measured by using the measuring equipment, then screwing the bolts to be measured to an elongation monitoring target value to perform an impact vibration test, and recording the actual vibration cycle of each bolt to be measured;
step S104, after the impact vibration test is finished, if all the tested bolts are loosened, determining whether the vibration resistance and the loose resistance of the tested bolts are good or bad according to actual vibration cycles; if the unreleased tested bolt exists, the clamping force retention rate of the unreleased tested bolt is calculated, and the anti-vibration and anti-loosening performance of the tested bolt is determined according to the clamping force retention rate.
In some embodiments, the strength grade, supplier, material, surface treatment form of the calibration test bolt is consistent with the strength grade, supplier, material, surface treatment form of the tested bolt.
In some embodiments, the assembly clamping length and the screw thread screwing length of the calibration test bolt are consistent with those of the tested bolt in the impact vibration test.
In some embodiments, the tightening of the plurality of bolts under test to the elongation monitoring target value is: and firstly, pre-tightening the bolt to be tested by applying 50% of bolt assembly torque, and then gradually applying the torque to screw the bolt to be tested to the elongation monitoring target value.
In some embodiments, the plurality of bolts to be tested have different diameters and strengths, with the bolts to be tested typically having diameters of 5-12mm.
In some embodiments, the measuring device is an ultrasonic measuring instrument, and the bolt ultrasonic elongation measuring technology does not damage the structure and the friction surface state of the bolt, so that the bolt elongation measured by the ultrasonic measuring instrument is the actual assembly elongation of the bolt.
In some embodiments, the retention rate of the clamping force of the unreleased tested bolt is a ratio of the clamping force of the unreleased tested bolt after the impact vibration test is finished to the assembly clamping force of the tested bolt before the impact vibration test, and the calculation formula is as follows: η=y Rear part (S) /y Front part Wherein eta represents the clamping force retention rate of the non-loosened tested bolt and y Rear part (S) Representing the clamping force of the unreleased tested bolt after the impact vibration test is finished, y Front part Representing the assembly clamping force of the tested bolt before the impact vibration test.
In some embodiments, the process of obtaining the clamping force of the unreleased tested bolt after the impact vibration test is finished is as follows: and measuring the residual elongation of the unreleased tested bolt after the impact vibration test is finished by using the measuring equipment, and inputting the value of the residual elongation into the corresponding relation between the axial clamping force and the elongation of the bolt to obtain the clamping force of the unreleased tested bolt after the impact vibration test is finished.
In some embodiments, the assembly clamping force of the tested bolt before the impact vibration test is the axial clamping force target value of the tested bolt during the impact vibration test.
In some embodiments, the number of the calibration test bolts is three or five, and by setting a plurality of calibration test bolts to perform parallel tests, measurement errors can be reduced, and an accurate corresponding relationship between axial clamping force and elongation of the bolts can be obtained.
In some embodiments, the greater the clamping force retention rate of the unreleased measured bolt, the better the anti-vibration and anti-loosening performance of the measured bolt.
The bolt connection pairs with different friction coefficients and different anti-loosening structures can obtain a fair and accurate test result and an accurate bolt anti-loosening performance evaluation result only by controlling the tightening of the bolt connection pairs with different friction coefficients and different anti-loosening structures under the same axial clamping force level, ensuring that the starting points of the tested bolt connection pairs are consistent and fair, and then performing an impact vibration comparison test; because the axial clamping force of the bolt is in direct proportion to the elongation and has stable relation, the axial clamping force of the bolts of the connecting pairs with different forms and large friction coefficient difference can be controlled to be screwed at the same level through the monitoring of the elongation of the bolts during screwing.
According to the method provided by the application, the relation between the axial clamping force and the elongation of the bolt is calibrated according to the assembly clamping length during the bolt test before the test, the elongation monitoring target value of the detected bolt is determined according to the axial clamping force target value, and the impact vibration test is performed after each detected bolt is screwed to the elongation monitoring target value, so that the detected bolt can be ensured to be controlled under the same axial clamping force condition.
The technical scheme provided by the application has the beneficial effects that: according to the method provided by the application, the bolt impact vibration test is carried out after the bolt connection pairs in different forms are controlled and screwed to the same axial clamping force, so that a fair and objective bolt anti-loosening performance test result can be obtained, the comparison and evaluation of the anti-loosening performance of the different bolt connection pairs can be accurately completed, the accurate selection of the different bolt connection pairs can be effectively guided, and the anti-loosening performance and reliability of the threaded connection of products are improved; according to the method provided by the application, the looseness prevention performance of the unreleased tested bolt after the impact vibration test is finished is evaluated according to the clamping force retention rate, and the accurate control and accurate evaluation system of the impact vibration test of the bolt connection pair is further perfected.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for evaluating anti-loosening performance test of a bolt connection pair according to an embodiment of the application;
FIG. 2 is a schematic view showing the structure of an apparatus for impact vibration test according to an embodiment of the present application;
FIG. 3 is a graph showing the correspondence between the axial clamping force and the elongation of the calibration test bolt according to example 1 of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The embodiment of the application provides a method for testing and evaluating the anti-loosening performance of a bolt connection pair, which can solve the problem that the existing bolt connection pair with the same strength grade and thread specification in the related technology cannot conduct the anti-loosening performance test under the same axial clamping force level.
Fig. 1 is a flow chart of an anti-loosening performance test and evaluation method for a bolt connection pair according to an embodiment of the present application, and referring to fig. 1, the anti-loosening performance test and evaluation method provided by the present application includes the following steps:
s101, on a bolt tightening performance testing machine, tightening calibration test bolts according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force of the calibration test bolts and the measured axial elongation; in the embodiment, the number of the calibration test bolts can be three or five, and the parallel test is performed by arranging a plurality of calibration test bolts, so that the measurement error can be reduced, and an accurate corresponding relation between the axial clamping force and the elongation of the bolts can be obtained;
step S102, inputting an axial clamping force target value of a detected bolt in an impact vibration test into a corresponding relation between the axial clamping force and the elongation of the bolt to obtain an elongation monitoring target value of the detected bolt;
step S103, respectively measuring the original lengths of a plurality of tested bolts by utilizing an ultrasonic measuring instrument, then pre-tightening the tested bolts by applying 50% of bolt assembly torque, gradually applying the torque to tighten the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt; the bolts to be tested have different diameters and strengths, and the diameters of the bolts to be tested are generally 5-12mm;
step S104, after the impact vibration test is finished, if all the tested bolts are loosened, determining whether the vibration resistance and the anti-loosening performance of the tested bolts are good or bad according to the actual vibration cycle of the tested bolts, wherein the larger the actual vibration cycle of the tested bolts is, the better the vibration resistance and the anti-loosening performance of the tested bolts is; if the unreleased measured bolt exists, the clamping force retention rate of the unreleased measured bolt is calculated, the anti-vibration and anti-loosening performance of the measured bolt is determined according to the clamping force retention rate, and the greater the clamping force retention rate of the unreleased measured bolt is, the better the anti-vibration and anti-loosening performance of the measured bolt is.
In the anti-loosening performance test evaluation method, the intensity level, the supplier, the material, the surface treatment form and the like of the calibration test bolt are required to be consistent with those of the tested bolt; the assembly clamping length and the screw thread screwing length of the calibration test bolt are ensured to be consistent with those of the tested bolt in the impact vibration test; the ultrasonic measuring instrument is the same equipment, and the bolt ultrasonic elongation measuring technology does not damage the structure and the friction surface state of the bolt, so that the bolt elongation measured by the ultrasonic measuring instrument is the actual assembly elongation of the bolt.
In step S104, the retention rate of the clamping force of the non-loosened tested bolt is the ratio of the clamping force of the non-loosened tested bolt after the impact vibration test is finished to the assembling clamping force of the tested bolt before the impact vibration test, and the calculation formula is as follows: η=y Rear part (S) /y Front part Wherein eta represents the clamping of the non-loosened tested boltForce retention, y Rear part (S) Representing the clamping force of the unreleased tested bolt after the impact vibration test is finished, y Front part The method comprises the steps of representing the assembly clamping force of a detected bolt before an impact vibration test, wherein the assembly clamping force of the detected bolt before the impact vibration test is the axial clamping force target value of the detected bolt during the impact vibration test; the retention of the clamping force of the test bolt that is not loosened can indicate the retention of the clamping force of the test bolt after the impact vibration test is completed.
The acquisition process of the clamping force of the unreleased tested bolt after the impact vibration test is finished is as follows: and measuring the residual elongation of the unreleased tested bolt after the impact vibration test is finished by using an ultrasonic measuring instrument, and inputting the value of the residual elongation into the corresponding relation between the axial clamping force and the elongation of the bolt to obtain the clamping force of the unreleased tested bolt after the impact vibration test is finished.
In the embodiment of the application, the structural diagram of the device for impact vibration test is shown in fig. 2, 100 represents a vibration table, 200 represents a test fixture, 300 represents a fixture chute, 400 represents a tested bolt, the tested bolt-nut connection pair can freely slide in the fixture chute after being screwed down, when the vibration table is excited according to the specified frequency and amplitude, the bolt-nut connection pair arranged in the fixture chute can continuously vibrate in a reciprocating manner until the bolt-nut connection pair loosens in vibration, and in the process, the actual vibration cycle of each tested bolt is recorded.
The bolt connection pairs with different friction coefficients and different anti-loosening structures can obtain a fair and accurate test result and an accurate bolt anti-loosening performance evaluation result only by controlling the tightening of the bolt connection pairs with different friction coefficients and different anti-loosening structures under the same axial clamping force level, ensuring that the starting points of the tested bolt connection pairs are consistent and fair, and then performing an impact vibration comparison test; because the axial clamping force of the bolt is in direct proportion to the elongation and has stable relation, the bolt clamping force of the connecting pairs with different forms and large friction coefficient difference can be controlled to be screwed at the same level through the monitoring of the elongation of the bolt during screwing.
According to the method provided by the application, the relation between the axial clamping force and the elongation of the bolt is calibrated according to the assembly clamping length during the bolt test before the test, the elongation monitoring target value of the detected bolt is determined according to the axial clamping force target value, and the impact vibration test is performed after each detected bolt is screwed to the elongation monitoring target value, so that the detected bolt can be ensured to be controlled under the same axial clamping force condition.
The method for evaluating the anti-loosening performance of the bolt connection pair according to the present application will be described in detail with reference to examples.
Example 1:
the embodiment 1 of the application provides a method for testing and evaluating the anti-loosening performance of a bolt connection pair, which comprises the following steps:
step S101, sequentially tightening calibration test bolts on a bolt tightening performance testing machine according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force and the measured axial elongation of the calibration test bolts, wherein an obtained corresponding relation graph between the axial clamping force and the elongation of the bolts is shown in FIG. 3, and in FIG. 3, the relation between the axial clamping force and the elongation of the bolts can be expressed as: y= -489.64x 3 +186.52x 2 +140.55x+1.5226, wherein y represents the axial clamping force of the calibration test bolt and x represents the axial elongation of the calibration test bolt; in the embodiment, the calibration test bolts are bolts with the diameter of 10mm and the length of 60mm, and the number of the calibration test bolts can be three;
step S102, knowing that the axial clamping force target value of the tested bolt is 30kN in the impact vibration test, searching the curve shown in FIG. 3 according to the value or inputting the value into a corresponding relation, namely determining the elongation monitoring target value of the tested bolt;
step S103, cleaning and wiping the tested bolts one by one, numbering and marking the tested bolts as a bolt I, a bolt II, a bolt III and a bolt IV respectively, measuring the original length of the tested bolts by utilizing an ultrasonic measuring instrument according to the numbering sequence of the tested bolts, pre-tightening the tested bolts by applying about 50% of bolt assembly torque, monitoring the elongation value of the tested bolts in real time in the pre-tightening process, gradually applying torque to screw the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt;
and S104, after the impact vibration test is finished, the bolts I, II, III and IV are found to be loosened, and the anti-vibration and anti-loosening performances of the tested bolt are determined according to the actual vibration cycles of the bolts I, II, III and IV, so that the larger the actual vibration cycles of the tested bolt are, the better the anti-vibration and anti-loosening performances of the tested bolt are.
Example 2:
the embodiment 2 of the application provides a method for testing and evaluating the anti-loosening performance of a bolt connection pair, which comprises the following steps:
step S101, sequentially tightening calibration test bolts on a bolt tightening performance testing machine according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force and the measured axial elongation of the calibration test bolts, wherein an obtained corresponding relation graph between the axial clamping force and the elongation of the bolts is the same as that of the embodiment 1; in the embodiment, the calibration test bolts are bolts with the diameter of 10mm and the length of 60mm, and the number of the calibration test bolts can be five;
step S102, knowing that the axial clamping force target value of the tested bolt is 35kN in the impact vibration test, searching the curve shown in FIG. 3 according to the value or inputting the value into a corresponding relation, namely determining the elongation monitoring target value of the tested bolt;
step S103, cleaning and wiping the tested bolts one by one, numbering the tested bolts as a bolt I, a bolt II, a bolt III, a bolt IV, a bolt V and a bolt VI … respectively, measuring the original length of the tested bolts according to the numbering sequence of the tested bolts by utilizing an ultrasonic measuring instrument, pre-tightening the tested bolts by applying about 50% of bolt assembly torque, monitoring the elongation value of the tested bolts in real time in the pre-tightening process, gradually applying torque to screw the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt;
step S104, after the impact vibration test is finished, the bolts III, IV and V in the fixture sliding groove are not loosened, then the residual elongations of the bolts III, IV and V are respectively measured by utilizing an ultrasonic measuring instrument, then the curves shown in the graph 3 are searched according to the residual elongations, so that the clamping forces of the bolts III, IV and V after the impact vibration test is finished are obtained, and according to the formula eta=y Rear part (S) /y Front part And calculating the clamping force retention rate of the bolts III, IV and V, wherein the larger the clamping force retention rate is, the better the vibration resistance and the loose resistance of the tested bolt are.
Example 3:
the embodiment 3 of the application provides a method for testing and evaluating the looseness prevention performance of a bolt connection pair, which comprises the following steps:
step S101, sequentially tightening calibration test bolts on a bolt tightening performance testing machine according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force and the measured axial elongation of the calibration test bolts, wherein an obtained corresponding relation graph between the axial clamping force and the elongation of the bolts is the same as that of the embodiment 1; in the embodiment, the calibration test bolts are bolts with the diameter of 10mm and the length of 60mm, and the number of the calibration test bolts can be five;
step S102, knowing that the axial clamping force target value of the tested bolt is 40kN in the impact vibration test, searching the curve shown in FIG. 3 according to the value or inputting the value into a corresponding relation, namely determining the elongation monitoring target value of the tested bolt;
step S103, cleaning and wiping the tested bolts one by one, numbering the tested bolts as a bolt I, a bolt II, a bolt III, a bolt IV, a bolt V and a bolt VI … respectively, measuring the original length of the tested bolts according to the numbering sequence of the tested bolts by utilizing an ultrasonic measuring instrument, pre-tightening the tested bolts by applying about 50% of bolt assembly torque, monitoring the elongation value of the tested bolts in real time in the pre-tightening process, gradually applying torque to screw the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt;
step S104, after the impact vibration test is finished, the bolts II, IV and V in the fixture sliding groove are not loosened, then the residual elongation of the bolts II, IV and V are respectively measured by utilizing an ultrasonic measuring instrument, then the curves shown in the graph 3 are searched according to the residual elongation values, and the clamping force of the bolts II, IV and V after the impact vibration test is finished is obtained, and according to the formula eta=y Rear part (S) /y Front part And calculating the clamping force retention rate of the bolts II, IV and V, wherein the larger the clamping force retention rate is, the better the vibration resistance and the loose resistance of the tested bolt are.
Example 4:
the embodiment 4 of the application provides a method for testing and evaluating the looseness prevention performance of a bolt connection pair, which comprises the following steps:
step S101, sequentially tightening calibration test bolts on a bolt tightening performance testing machine according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force and the measured axial elongation of the calibration test bolts, wherein an obtained corresponding relation graph between the axial clamping force and the elongation of the bolts is the same as that of the embodiment 1; in the embodiment, the calibration test bolts are bolts with the diameter of 10mm and the length of 60mm, and the number of the calibration test bolts can be five;
step S102, knowing that the axial clamping force target value of the tested bolt is 45kN in the impact vibration test, searching the curve shown in FIG. 3 according to the value or inputting the value into a corresponding relation, namely determining the elongation monitoring target value of the tested bolt;
step S103, cleaning and wiping the tested bolts one by one, numbering the tested bolts as a bolt I, a bolt II, a bolt III, a bolt IV, a bolt V and a bolt VI … respectively, measuring the original length of the tested bolts according to the numbering sequence of the tested bolts by utilizing an ultrasonic measuring instrument, pre-tightening the tested bolts by applying about 50% of bolt assembly torque, monitoring the elongation value of the tested bolts in real time in the pre-tightening process, gradually applying torque to screw the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt;
step S104, after the impact vibration test is finished, the bolts I, III and V in the fixture sliding groove are not loosened, then the residual elongations of the bolts I, III and V are respectively measured by utilizing an ultrasonic measuring instrument, and then the curves shown in the graph 3 are searched according to the residual elongations, so that the clamping forces of the bolts I, III and V after the impact vibration test is finished are obtained, and according to the formula eta=y Rear part (S) /y Front part And calculating the clamping force retention rate of the bolts I, III and V, wherein the larger the clamping force retention rate is, the better the vibration resistance and the loose resistance of the tested bolt are.
Example 5:
the embodiment 5 of the application provides a method for testing and evaluating the looseness prevention performance of a bolt connection pair, which comprises the following steps:
step S101, sequentially tightening calibration test bolts on a bolt tightening performance testing machine according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using an ultrasonic measuring instrument, and establishing a corresponding relation between the axial clamping force and the elongation of the bolts according to the axial clamping force and the measured axial elongation of the calibration test bolts, wherein an obtained corresponding relation graph between the axial clamping force and the elongation of the bolts is the same as that of the embodiment 1; in the embodiment, the calibration test bolts are bolts with the diameter of 10mm and the length of 60mm, and the number of the calibration test bolts can be five;
step S102, knowing that the axial clamping force target value of the tested bolt is 55kN in the impact vibration test, searching the curve shown in FIG. 3 according to the value or inputting the value into a corresponding relation, namely determining the elongation monitoring target value of the tested bolt;
step S103, cleaning and wiping the tested bolts one by one, numbering the tested bolts as a bolt I, a bolt II, a bolt III, a bolt IV, a bolt V and a bolt VI … respectively, measuring the original length of the tested bolts according to the numbering sequence of the tested bolts by utilizing an ultrasonic measuring instrument, pre-tightening the tested bolts by applying about 50% of bolt assembly torque, monitoring the elongation value of the tested bolts in real time in the pre-tightening process, gradually applying torque to screw the tested bolts to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each tested bolt;
step S104, after the impact vibration test is finished, the bolts I, III and IV in the fixture sliding groove are not loosened, residual elongations of the bolts I, III and IV are respectively measured by utilizing an ultrasonic measuring instrument, and then curves shown in the graph 3 are searched according to the residual elongation values, so that clamping forces of the bolts I, III and IV after the impact vibration test is finished are obtained, and according to a formula eta=y Rear part (S) /y Front part And calculating the clamping force retention rate of the bolts I, III and IV, wherein the larger the clamping force retention rate is, the better the vibration resistance and the loose resistance of the tested bolt are.
According to the method provided by the application, the bolt impact vibration test is carried out after the bolt connection pairs in different forms are controlled and screwed to the same axial clamping force, so that a fair and objective bolt anti-loosening performance test result can be obtained, the comparison and evaluation of the anti-loosening performance of the different bolt connection pairs can be accurately completed, the accurate selection of the different bolt connection pairs can be effectively guided, and the anti-loosening performance and reliability of the threaded connection of products are improved; according to the method provided by the application, the looseness prevention performance of the unreleased tested bolt after the impact vibration test is finished is evaluated according to the clamping force retention rate, and the accurate control and accurate evaluation system of the impact vibration test of the bolt connection pair is further perfected.
In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present application and simplifying the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present application. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
It should be noted that in the present application, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. The method for testing and evaluating the looseness prevention performance of the bolt connection pair is characterized by comprising the following steps of:
tightening the calibration test bolts according to different axial clamping forces, measuring the axial elongation of the calibration test bolts after tightening by using measuring equipment, and establishing a corresponding relation between the axial clamping force and the axial elongation of the bolts according to the axial clamping force and the axial elongation of the calibration test bolts;
inputting the target value of the axial clamping force of the tested bolt in the impact vibration test into the corresponding relation of the axial clamping force and the elongation of the bolt to obtain the elongation monitoring target value of the tested bolt;
respectively screwing a plurality of bolts to be tested to an elongation monitoring target value for impact vibration test, and recording the actual vibration cycle of each bolt to be tested;
after the impact vibration test is finished, if all the tested bolts are loosened, determining the vibration resistance and the loose resistance of the tested bolts according to actual vibration cycles; if the unreleased measured bolt exists, calculating the clamping force retention rate of the unreleased measured bolt, and determining the vibration resistance and looseness resistance of the measured bolt according to the clamping force retention rate;
the clamping force retention rate of the unreleased tested bolt is the ratio of the clamping force of the unreleased tested bolt after the impact vibration test is finished to the assembling clamping force of the tested bolt before the impact vibration test;
the process of tightening the plurality of bolts to be tested to the elongation monitoring target value is as follows: and firstly, pre-tightening the bolt to be tested by applying 50% of bolt assembly torque, and then gradually applying the torque to screw the bolt to be tested to the elongation monitoring target value.
2. The method for evaluating the anti-loosening performance test of the bolt connection pair according to claim 1, wherein the strength grade, the supplier, the material and the surface treatment form of the calibration test bolt are identical to those of the tested bolt.
3. The method for evaluating the anti-loosening performance of the bolt connection pair according to claim 1, wherein the assembly clamping length and the screw thread screwing length of the calibration test bolt are identical to those of the tested bolt in the impact vibration test.
4. The method for evaluating the anti-loosening performance of a bolting pair according to claim 1, wherein the measuring device is an ultrasonic measuring instrument.
5. The method for evaluating the anti-loosening performance of the bolt connection pair according to claim 1, wherein the process of obtaining the clamping force of the unreleased tested bolt after the impact vibration test is finished is as follows: and measuring the residual elongation of the unreleased tested bolt after the impact vibration test is finished by using the measuring equipment, and inputting the value of the residual elongation into the corresponding relation between the axial clamping force and the elongation of the bolt to obtain the clamping force of the unreleased tested bolt after the impact vibration test is finished.
6. The method for evaluating the anti-loosening performance of a bolted joint according to claim 1, wherein the assembly clamping force of the bolt under test before the impact vibration test is a target value of the axial clamping force of the bolt under test at the time of the impact vibration test.
7. The method for evaluating the anti-loosening performance test of a bolting pair according to claim 1, wherein a plurality of bolts to be tested have different diameters and strengths.
8. The method for evaluating the anti-loosening performance test of a bolting pair according to claim 1, wherein the greater the clamping force retention rate of the non-loosened bolt under test, the better the anti-loosening performance of the bolt under test.
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