Device and method for detecting the fit of a connecting rod bushing by means of a vibration signal

Abstract

The application provides a device and method for detecting the vibration signal of a connecting rod bushing fit degree, and belongs to the technical field of connecting rod bushings. The device comprises a knocking device, a dynamic test analyzer, a computer, an acceleration sensor, a large-hole clamp seat, a base, a supporting block and a large-hole clamp. Force and acceleration data are obtained through the acceleration sensor and the force sensor, and the force and acceleration data are processed through the dynamic test analyzer to obtain the natural frequency of the connecting rod bushing. The data of the natural frequency of the connecting rod bushing are matched with the data of a standard library through the computer to obtain the connecting rod bushing fit degree. The vibration signal is used to determine the fit degree of the connecting rod bushing, so that the error of manual judgment is avoided, and the detection quality and detection efficiency are improved. Moreover, the workpiece does not need to be damaged, and resource waste is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of connecting rod bushing, and particularly relates to a device and method for detecting the fit degree of a connecting rod bushing through vibration signals. BACKGROUND

[0002] With the increasing quality requirements of the manufacturing industry and the environmental protection appeal of energy saving and emission reduction, more stringent requirements are put forward for the production quality of connecting rods.

[0003] A connecting rod is an important component of an automobile engine. It connects a piston and a crankshaft. Its function is to convert the reciprocating motion of the piston into the rotary motion of the crankshaft and transmit the force acting on the piston to the crankshaft to output power. In the running process, the connecting rod not only bears the pressure generated by the combustion chamber gas, but also bears the longitudinal and transverse inertia forces. Therefore, the connecting rod works under a complex stress state. There is a bushing between the connecting rod and the crankshaft, and the main function of the bushing is to reduce vibration, reduce noise, reduce fatigue and prolong the service life of the connecting rod.

[0004] The fit between the bushing and the connecting rod hole has an important influence on the use performance of the connecting rod, especially when there is a gap between the fit of the connecting rod bushing and the connecting rod hole, which will seriously affect the use of the connecting rod.

[0005] The assembly of the bushing and the connecting rod hole is mostly by interference fit, and the pressure generated by the interference fit between them is connected together. When there is a large gap between the fit of the bushing and the hole, it will seriously affect the use performance of the connecting rod, and axial jumping or rotation will occur, dry friction will occur, which will cause severe wear, and the connecting rod hole will directly bear the impact of the non-periodic complex alternating load of the piston pin, thereby causing stress concentration, leading to the fracture of the connecting rod or causing cylinder seizure, cylinder pounding and piston burnout, etc. Therefore, it is necessary to inspect the fit degree of the outer wall of the bushing and the inner wall of the connecting rod hole.

[0006] The traditional way to detect the fit degree of the connecting rod bushing is mainly by destructive sampling inspection. For example: the bushing with red powder on the outer wall is pressed into the connecting rod small hole according to the normal assembly method, and then pressed out. The red powder on the fit will peel off, and then the transparent tape is used to transfer the traces on the outer circular surface of the bushing to the prepared grid paper, so as to judge the fit area.

[0007] This detection method has many disadvantages: it destroys the workpiece and wastes resources; it can only be sampled for detection, and the reliability is low; it is manually operated, and the detection efficiency is low.

[0008] Chinese invention patent CN110160424A discloses a connecting rod bushing fit degree detection tool and detection method, which comprises a cylindrical tool body provided with a plurality of arc-shaped detection windows in the circumferential direction; the connecting rod bushing and the tool body can be matched with high precision, and the real form of the connecting rod bushing in the connecting rod small head can be accurately reflected. The detection method comprises the following steps: firstly, the connecting rod bushing is pressed into the tool body, the tool body with the connecting rod bushing is placed on the detection table, and the three-coordinate or the cylindricity instrument is calibrated; then, the detection probe is used to measure the roundness of the outer surface of the connecting rod bushing at different heights in the detection window, and the cylindricity of the outer surface of the connecting rod bushing is obtained by fitting the measurement data; finally, the fit degree is determined according to the cylindricity, and if the cylindricity is within the specified range, it is qualified; the fit rate of the connecting rod bushing and the connecting rod small head can be quickly and accurately evaluated, and the situation of large data fluctuation caused by human operation can be avoided. However, since the connecting rod bushing is pressed into the tool body with a certain interference, the process of taking out the connecting rod bushing is a destructive process, and the connecting rod bushing cannot be used after being taken out, causing waste of resources; in general, the tool body is only used for equipment debugging and product initial inspection, and the reliability is low; and the cylindricity detection is performed on the outer surface of the bushing at the detection window, but the outer surface at the detection window is not directly extruded, so the cylindricity measured at this position is not accurate. SUMMARY

[0009] In view of the problems in the prior art, the present application provides a device and method for detecting the fit degree of a connecting rod bushing by using a vibration signal, and aims to improve the detection accuracy of the fit degree of the connecting rod bushing and avoid resource waste during the detection process.

[0010] To solve the above technical problems, the present application provides a device for detecting the fit degree of a connecting rod bushing by using a vibration signal, which comprises a knocking device, a dynamic test analyzer, a computer, an acceleration sensor and a clamp device. The clamp device comprises a large-hole clamp seat, a base, a support block and a large-hole clamp. The connecting rod is arranged on the upper surface of the large-hole clamp seat, the lower surfaces of the large-hole clamp seat and the support block are connected with the base, and the lower part of the large-hole clamp is connected with the large-hole clamp seat.

[0011] One end of the knocking device is connected with the dynamic test analyzer, the dynamic test analyzer is electrically connected with the computer, and the acceleration sensor is electrically connected with the dynamic test analyzer.

[0012] The large-hole clamp comprises a positioning block and a positioning block track, the positioning block track is slidably connected with the lower part of the positioning block, and the positioning block can slide along the positioning block track.

[0013] The knocking device further comprises a force sensor, and the force sensor is electrically connected with the dynamic test analyzer.

[0014] The dynamic test analyzer can perform modal analysis on the data detected by the force sensor and the acceleration sensor, and the computer receives the modal analysis data and performs analysis and processing.

[0015] Further, the acceleration sensor is connected to the inner surface of the bushing.

[0016] Further, the number of acceleration sensors is multiple, and the multiple acceleration sensors are located on the same horizontal plane.

[0017] Further, the single positioning block and the single positioning block track are a set of positioning components, and the big hole clamp includes multiple sets of positioning components.

[0018] Further, the positioning block track is opened in the inside of the big hole clamp seat.

[0019] Further, the positioning block track is connected to the upper surface of the big hole clamp seat.

[0020] A method for detecting the fit degree of a connecting rod bushing through a vibration signal, for the device for detecting the fit degree of a connecting rod bushing through a vibration signal, comprising the following steps:

[0021] Step S1. First, place the connecting rod assembled with the bushing on the clamp device for positioning;

[0022] Step S2. Use the knocking device to knock the connecting rod;

[0023] Step S3. The force sensor and the acceleration sensor obtain force and acceleration data and transmit them to the dynamic test analyzer for processing;

[0024] Step S4. The dynamic test analyzer processes the force and acceleration data to obtain the frequency response function and the natural frequency of the connecting rod bushing, and the dynamic analysis tester transmits the natural frequency data to the computer;

[0025] Step S5. The computer matches the data of the natural frequency of the connecting rod bushing with the data of the standard library to obtain the fit degree of the connecting rod bushing.

[0026] Further, in step S2, the knocking device is used to knock the position on the connecting rod where the acceleration is the largest.

[0027] Further, in step S5, the standard library is established by sequentially performing steps S1, S2, S3 and S4 on multiple connecting rods to obtain the natural frequency, and then obtaining the fit degree by destructive testing.

[0028] Further, in step S5, the interpolation method is used to obtain the fit degree of the connecting rod bushing.

[0029] Further, the interpolation method is adopted in the step S5 to obtain the fit degree of the connecting rod bushing, adjacent points are selected according to the natural frequency of the measured connecting rod bushing, the natural frequency and the fit degree of the adjacent points are known, a straight line equation of the adjacent points is established, the measured natural frequency is substituted into the straight line equation, and the fit degree value corresponding to the natural frequency of the measured connecting rod bushing is obtained.

[0030] Specifically, the calculation process of the interpolation method is as follows:

[0031] There are a plurality of points, such as A and B, in the standard library, and the natural frequency and the fit degree coordinates of these points are known, when the natural frequency of an actual measured point C is obtained, the fit degree data of the C point is as follows: the natural frequency value is connected with the two points (assuming A and B) adjacent to the C point, the equation of the straight line AB is established, and the natural frequency of the C point is substituted into the equation to obtain the fit degree value of the C point.

[0032] The device for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the positioning block and the positioning block track are arranged, and the translation movement of the connecting rod is limited; the moving distance of the positioning block of the large hole clamp and the height of the supporting block can be adjusted, so that the demand for connecting rods of different sizes can be met; the dynamic test analyzer, the computer, the knocking device and the acceleration sensor are arranged, the fit degree of the connecting rod bushing is measured by the vibration signal, the error of manual judgment is avoided, and the detection quality and the detection efficiency are improved; and the workpiece does not need to be damaged, and the waste of resources is avoided.

[0033] The method for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the integrity of the connecting rod bushing does not need to be damaged, the economic loss is reduced, all products can be detected, the yield is improved, the error of manual judgment is avoided, the detection quality and the detection efficiency are improved, and the detection accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The device for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the positioning block and the positioning block track are arranged, and the translation movement of the connecting rod is limited; the moving distance of the positioning block of the large hole clamp and the height of the supporting block can be adjusted, so that the demand for connecting rods of different sizes can be met; the dynamic test analyzer, the computer, the knocking device and the acceleration sensor are arranged, the fit degree of the connecting rod bushing is measured by the vibration signal, the error of manual judgment is avoided, and the detection quality and the detection efficiency are improved; and the workpiece does not need to be damaged, and the waste of resources is avoided.

[0035] Figure 2 The device for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the positioning block and the positioning block track are arranged, and the translation movement of the connecting rod is limited; the moving distance of the positioning block of the large hole clamp and the height of the supporting block can be adjusted, so that the demand for connecting rods of different sizes can be met; the dynamic test analyzer, the computer, the knocking device and the acceleration sensor are arranged, the fit degree of the connecting rod bushing is measured by the vibration signal, the error of manual judgment is avoided, and the detection quality and the detection efficiency are improved; and the workpiece does not need to be damaged, and the waste of resources is avoided.

[0036] Figure 3 The device for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the positioning block and the positioning block track are arranged, and the translation movement of the connecting rod is limited; the moving distance of the positioning block of the large hole clamp and the height of the supporting block can be adjusted, so that the demand for connecting rods of different sizes can be met; the dynamic test analyzer, the computer, the knocking device and the acceleration sensor are arranged, the fit degree of the connecting rod bushing is measured by the vibration signal, the error of manual judgment is avoided, and the detection quality and the detection efficiency are improved; and the workpiece does not need to be damaged, and the waste of resources is avoided.

[0037] Figure 4 The device for detecting the fit degree of the connecting rod bushing by the vibration signal is provided, the positioning block and the positioning block track are arranged, and the translation movement of the connecting rod is limited; the moving distance of the positioning block of the large hole clamp and the height of the supporting block can be adjusted, so that the demand for connecting rods of different sizes can be met; the dynamic test analyzer, the computer, the knocking device and the acceleration sensor are arranged, the fit degree of the connecting rod bushing is measured by the vibration signal, the error of manual judgment is avoided, and the detection quality and the detection efficiency are improved; and the workpiece does not need to be damaged, and the waste of resources is avoided.

[0038] Figure 5A flow chart of a method for detecting the fit of a connecting rod bushing by a vibration signal according to an embodiment of the present application.

[0039] Figure 6 An interpolation method schematic diagram of a method for detecting the fit of a connecting rod bushing by a vibration signal according to an embodiment of the present application.

[0040] Figure 7 An interpolation method schematic diagram of a method for detecting the fit of a connecting rod bushing by a vibration signal according to an embodiment of the present application.

[0041] Wherein, 1, knocking device; 2, dynamic test analyzer; 3, computer; 4, connecting rod; 5, big head hole clamp seat; 6, base; 7, supporting block; 8, acceleration sensor; 9, big head hole clamp; 10, bushing; 91, positioning block. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0043] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0044] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0045] In the present application, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting”, “fixing” and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In order to better understand the purpose, structure and function of the present application, the device and method for detecting the fit degree of a connecting rod bushing through a vibration signal are described in further detail below in combination with the drawings.

[0047] Embodiment 1

[0048] As shown in Figure 1 and Figure 2 , the present embodiment provides a device for detecting the fit degree of a connecting rod bushing through a vibration signal, which comprises a knocking device 1, a dynamic test analyzer 2, a computer 3, a big-hole clamp seat 5, a base 6, a support block 7, an acceleration sensor 8 and a big-hole clamp 9; a connecting rod 4 is arranged on the upper surface of the big-hole clamp seat 5, the lower surfaces of the big-hole clamp seat 5 and the support block 7 are connected with the base 6, and the lower part of the big-hole clamp 9 is connected with the big-hole clamp seat 5.

[0049] One end of the knocking device 1 is connected with the dynamic test analyzer 2, the dynamic test analyzer 2 is electrically connected with the computer 3, and the acceleration sensor is electrically connected with the dynamic test analyzer 2.

[0050] The big-hole clamp 9 comprises a positioning block 91 and a positioning block track, the positioning block track is slidably connected with the lower part of the positioning block 91, and the positioning block 91 can slide along the positioning block track to limit the movement freedom degree of the connecting rod 5.

[0051] The knocking device 1 further comprises a force sensor, and the force sensor is electrically connected with the dynamic test analyzer 2.

[0052] The dynamic test analyzer 2 can perform modal analysis on the data detected by the force sensor and the acceleration sensor 8, and the computer 3 receives the data of the modal analysis and performs analysis and processing.

[0053] Embodiment 2

[0054] As shown in Figure 1 and Figure 2 , the present embodiment provides a device for detecting the fit degree of a connecting rod bushing through a vibration signal, which comprises a knocking device 1, a dynamic test analyzer 2, a computer 3, a big-hole clamp seat 5, a base 6, a support block 7, an acceleration sensor 8 and a big-hole clamp 9; a connecting rod 4 is arranged on the upper surface of the big-hole clamp seat 5, the lower surfaces of the big-hole clamp seat 5 and the support block 7 are connected with the base 6, and the lower part of the big-hole clamp 9 is connected with the big-hole clamp seat 5.

[0055] One end of the knocking device 1 is connected with the dynamic test analyzer 2, the dynamic test analyzer 2 is electrically connected with the computer 3, and the acceleration sensor 8 is electrically connected with the dynamic test analyzer 2.

[0056] The big head hole clamp 9 comprises a positioning block 91 and a positioning block track, the positioning block track is in sliding connection with the lower part of the positioning block 91, the positioning block 91 can slide along the positioning block track, and the movement freedom degree of the connecting rod 5 is limited;

[0057] The knocking device 1 further comprises a force sensor, and the force sensor is in electrical connection with the dynamic test analyzer 2;

[0058] The dynamic test analyzer 2 can perform modal analysis on the data detected by the force sensor and the acceleration sensor 8, and the computer 3 receives the data of the modal analysis and performs analysis and processing.

[0059] The difference between the embodiment and the first embodiment is that:

[0060] The single positioning block 91 and the single positioning block track form a positioning assembly, the big head hole clamp 9 comprises a plurality of positioning assemblies, each positioning block 91 moves on the respective positioning block track at an equal speed to the direction close to the inner surface of the big head hole of the connecting rod, and stops after touching the inner wall of the big head hole, thereby limiting the translational movement of the connecting rod 5.

[0061] The positioning block track is arranged in the interior of the big head hole clamp base 5; the positioning block track can also be a sliding rail connected to the upper surface of the big head hole clamp base 5.

[0062] Embodiment 3:

[0063] As shown in Figure 1 and Figure 2 The embodiment provides a device for detecting the fit degree of a connecting rod bushing through a vibration signal, which comprises a knocking device 1, a dynamic test analyzer 2, a computer 3, a big head hole clamp base 5, a base 6, a supporting block 7, an acceleration sensor 8 and a big head hole clamp 9; the connecting rod 4 is arranged on the upper surface of the big head hole clamp base 5, the lower surfaces of the big head hole clamp base 5 and the supporting block 7 are connected with the base 6, and the lower part of the big head hole clamp 9 is connected with the big head hole clamp base 5;

[0064] One end of the knocking device 1 is connected with the dynamic test analyzer 2, the dynamic test analyzer 2 is in electrical connection with the computer 3, and the acceleration sensor 8 is in electrical connection with the dynamic test analyzer 2;

[0065] The big head hole clamp 9 comprises a positioning block 91 and a positioning block track, the positioning block track is in sliding connection with the lower part of the positioning block 91, the positioning block 91 can slide along the positioning block track, and the movement freedom degree of the connecting rod 5 is limited;

[0066] The knocking device 1 further comprises a force sensor, and the force sensor is in electrical connection with the dynamic test analyzer 2;

[0067] The dynamic test analyzer 2 can perform modal analysis on the data detected by the force sensor and the acceleration sensor 8, and the computer 3 receives the modal analysis data and performs analysis and processing.

[0068] The difference between this embodiment and the first embodiment is that:

[0069] As shown in Figure 3 and Figure 4 , the acceleration sensor 8 is connected to the inner surface of the bushing 10, and a plurality of sensors 8 are uniformly distributed on the inner surface of the bushing 10, and the plurality of sensors 8 are located on the same horizontal plane, for detecting the acceleration of the bushing 10 when the knocking device 1 knocks; the force sensor is used to detect the size of the force when knocking.

[0070] The working process of the device for detecting the vibration signal of the connecting rod bushing fit degree is as follows:

[0071] Position the connecting rod 4: the lower surface of the large end of the connecting rod 4 is attached to the upper surface of the large hole clamp seat 5, the large hole clamp 9 is located inside the large hole of the connecting rod 4, and the lower surface of the connecting rod body is attached to the support block 7;

[0072] Then the positioning block 91 moves at an equal speed on the respective positioning block track towards the direction of the inner surface of the large hole of the connecting rod, stops after touching the inner wall of the large hole, at this time, the small hole part is similar to a cantilever beam structure suspended outside, which is convenient for subsequent vibration; by adjusting the moving distance of the positioning block 91 of the large hole clamp 9 and the height of the support block 7, the needs of connecting rods of different sizes can be met.

[0073] After positioning, a single knock is performed by the knocking device 1 at a certain fixed position of the connecting rod (the vibration effect at each position is different, and the acceleration sensor 8 records the data at different positions of the connecting rod, such as the small hole surface, the middle section of the connecting rod, the small hole surface, the side surface of the connecting rod, etc., and selects the knocking position with the largest acceleration as the subsequent fixed position for vibration test), so that the connecting rod 4 generates vibration. The knocking device 1 is provided with a force sensor, which can record the size of the force when knocking, and the acceleration sensor 8 is placed on the bushing 10, and the data of the force sensor and the acceleration sensor 8 are processed in the dynamic test analyzer 2 to obtain the frequency response function related to force and acceleration, and the natural frequency of the connecting rod bushing can be directly obtained by modal analysis using the software provided by the dynamic test analyzer 2; the dynamic analysis tester 2 transmits the natural frequency to the computer 3, and the computer 3 matches the obtained natural frequency data with the data in the standard library, so as to obtain the value of the fit degree of the connecting rod bushing detected this time.

[0074] The application provides a device for detecting the fit degree of a connecting rod bushing through vibration signals, and the device is characterized in that the device comprises a connecting rod 4, a support block 7, a big-hole clamp 9, a dynamic test analyzer 2, a computer 3, a knocking device 1 and an acceleration sensor 8.

[0075] Embodiment 4

[0076] As shown in the figure, the embodiment provides a method for detecting the fit degree of a connecting rod bushing through vibration signals, and the steps are as follows: Figure 5

[0077] Step S1. First, place the connecting rod 4 assembled with the bushing 10 on the clamp device for positioning;

[0078] Step S2. Use the knocking device 1 to knock the connecting rod 4;

[0079] Step S3. The force sensor and the acceleration sensor acquire force and acceleration data and transmit the data to the dynamic test analyzer 2 for processing;

[0080] Step S4. The dynamic test analyzer 2 processes to obtain the frequency response function and the natural frequency of the connecting rod bushing, and the dynamic analysis tester 2 transmits the natural frequency data to the computer 3;

[0081] Step S5. The computer 3 matches the data of the natural frequency with the data of the standard library to obtain the fit degree of the connecting rod bushing.

[0082] Embodiment 5

[0083] As shown in the figure, the embodiment provides a method for detecting the fit degree of a connecting rod bushing through vibration signals, and the steps are as follows: Figure 5

[0084] Step S1. First, place the connecting rod 4 assembled with the bushing 10 on the clamp device for positioning;

[0085] Step S2. Use the knocking device 1 to knock the connecting rod 4;

[0086] Step S3. The force sensor and the acceleration sensor acquire force and acceleration data and transmit the data to the dynamic test analyzer 2 for processing;

[0087] Step S4. The dynamic test analyzer 2 processes to obtain the frequency response function and the natural frequency of the connecting rod bushing, and the dynamic analysis tester 2 transmits the natural frequency data to the computer 3; ​​

[0088] Step S5. The computer 3 matches the data of the natural frequency with the data of the standard library to obtain the fit degree of the connecting rod bushing.

[0089] The fixture device in the step S1 includes a big hole fixture 9 and a support block 7, the big hole fixture 9 includes positioning blocks 91 and positioning block tracks, the positioning blocks 91 move on the respective positioning block tracks at equal speeds to the direction close to the inner surface of the connecting rod big hole, stop after touching the inner wall of the big hole, and the support block 7 is supported on the lower surface of the connecting rod body, at this time, the small hole part is similar to a cantilever beam structure suspended, and the positioning is completed.

[0090] The knocking device 1 is used in the step S2 to knock the position with the maximum acceleration on the connecting rod 4;

[0091] The determination method of the position with the maximum acceleration is that the acceleration data recorded by the acceleration sensor 8 is observed by knocking at different positions of the connecting rod 4, such as the small hole surface, the middle segment of the connecting rod, the small hole surface and the side surface of the connecting rod, and the knocking position with the maximum acceleration is selected as the fixed position for the subsequent vibration test.

[0092] The dynamic test analyzer 2 processes the frequency response function obtained in the step S4, and then performs modal analysis on the frequency response function to obtain the natural frequency of the connecting rod bushing.

[0093] The standard library in the step S5 includes the natural frequency and the fit degree data, and the standard library is established by using a plurality of connecting rods to sequentially perform the above steps S1, S2, S3 and S4, recording the corresponding natural frequency, and then obtaining the fit degree by a traditional destructive detection method.

[0094] The data of the standard library is discrete, and the actually measured natural frequency cannot be exactly the same as the natural frequency of the standard library, so the interpolation method is used for fitting.

[0095] The interpolation method is used in the step S5 to obtain the fit degree of the connecting rod bushing, the adjacent points of the measured natural frequency are selected, the natural frequencies and the fit degrees of the adjacent points are known, a straight line equation of the adjacent points is established, the measured natural frequency is substituted into the straight line equation, and the fit degree value corresponding to the measured natural frequency is obtained.

[0096] The specific calculation process of the interpolation method is as follows:

[0097] For example, Figure 6 and Figure 7As shown, the standard library has several points, such as A and B, and the natural frequency and the fitting degree coordinates of the points are known, when the natural frequency of a point C is actually measured, the fitting degree data of the point C is as follows: the natural frequency value is connected with the two points adjacent to the point C (assuming A and B), the equation of the straight line AB is established, and the fitting degree value of the point C is obtained by substituting the natural frequency of the point C into the equation.

[0098] The purpose of the present application is to detect the fitting of the bushing through the vibration response of the connecting rod structure and the analysis of the system dynamic characteristic parameters. The principle is as follows:

[0099] Each structure has its typical dynamic characteristics, also known as "vibration label". The change of a physical parameter, such as various damages leading to the decrease of bearing capacity, will affect the dynamic performance. The modal parameters of the structure include natural frequency, mode shape and damping ratio, etc. These parameters reflect the real state of the structure, and can be used to update the mathematical model of the structure, or compared with the reference data obtained by previous tests. These test results are very accurate and have qualitative value, that is, the integrity of the structure can be evaluated by detecting the change of the modal parameters.

[0100] In theory, by comparing the natural frequency, damping ratio and mode shape of the detection piece and the standard piece, whether the detection piece has defects can be found. The frequency response function obtained from the experiment can be used to identify the above-mentioned modal parameters, and the frequency response function includes the structural dynamics information contained in the above-mentioned modal parameters, so the defect detection can also be carried out by directly comparing the frequency response functions

[0101] The present application provides a method for detecting the fitting degree of the connecting rod bushing through vibration signals, which does not need to damage the integrity of the connecting rod bushing, reduces the economic loss, and can detect all products, improves the yield, avoids the error of manual judgment, improves the detection quality and detection efficiency, and improves the detection accuracy by measuring the fitting degree of the connecting rod bushing through vibration signals.

[0102] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application is included in the protection scope of the present application.

Claims

1. A method of detecting the fit of a connecting rod bushing by a vibration signal, characterized by, The device for detecting the fit degree of the connecting rod bushing through vibration signal comprises a knocking device, a dynamic test analyzer, a computer, an acceleration sensor and a clamp device, the clamp device comprises a big hole clamp seat, a base, a support block and a big hole clamp, the connecting rod is arranged on the upper surface of the big hole clamp seat, the lower surfaces of the big hole clamp seat and the support block are connected with the base, and the lower part of the big hole clamp is connected with the big hole clamp seat. One end of the knocking device is connected with the dynamic test analyzer, the dynamic test analyzer is electrically connected with the computer, and the acceleration sensor is electrically connected with the dynamic test analyzer. The big hole clamp comprises a positioning block and a positioning block track, the positioning block track is slidably connected with the lower part of the positioning block, and the positioning block can slide along the positioning block track. The knocking device further comprises a force sensor, and the force sensor is electrically connected with the dynamic test analyzer. The dynamic test analyzer can perform modal analysis on the data detected by the force sensor and the acceleration sensor, and the computer receives the data of the modal analysis and performs analysis and processing. The method for detecting the fit degree of the connecting rod bushing through vibration signal comprises the following steps: Step S1: first, the connecting rod assembled with the bushing is positioned on the clamp device; Step S2: the connecting rod is knocked by using the knocking device; Step S3: the force sensor and the acceleration sensor acquire force and acceleration data and transmit the data to the dynamic test analyzer for processing; Step S4: the dynamic test analyzer processes the force and acceleration data to obtain the frequency response function and the natural frequency of the connecting rod bushing, and the dynamic analysis test instrument transmits the natural frequency data to the computer; Step S5: the computer matches the data of the natural frequency of the connecting rod bushing with the data of the standard library to obtain the fit degree of the connecting rod bushing; The standard library in the step S5 is established by sequentially performing the steps S1, S2, S3 and S4 on a plurality of connecting rods to obtain the natural frequency, and then obtaining the fit degree by a destructive detection method; In the step S5, the interpolation method is adopted to obtain the fit degree of the connecting rod bushing.

2. The method of claim 1, wherein The acceleration sensor is connected with the inner surface of the bushing.

3. The method of claim 2, wherein The number of the acceleration sensors is multiple, and the multiple acceleration sensors are located on the same horizontal plane.

4. The method of claim 1, wherein The single positioning block and the single positioning block track form a positioning assembly, and the big hole clamp comprises multiple positioning assemblies.

5. The method of claim 1, wherein The positioning block track is arranged in the interior of the big hole clamp seat.

6. The method of claim 1, wherein The positioning block track is connected to the upper surface of the big hole clamp seat.

7. The method of claim 6, wherein In the step S2, the position with the maximum acceleration on the connecting rod is knocked by using the knocking device.

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