Device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod and method therefor

Abstract

Device for analysing internal thread deformation in an engine connecting rod comprises: a detection table 1 with a computer 2, a left fixture unit, a right fixture unit, and a detection unit. The left

Description

DEVICE FOR TESTING AND ANALYZING THREAD DEFORMATION OF INTERNAL THREADED HOLE IN ENGINE CONNECTING ROD AND METHOD THEREFOR TECHNICAL FIELD The present disclosure relates to the technical field of engine connecting rod detection, in particular to a device for testing and analyzing thread deformation of an internal threaded hole in an engine connecting rod and a method therefor. BACKGROUND As an important component of automobile engine, the reliability of connecting rods directly affects the safety performance of automobile. When the threaded pair of a connecting rod is tightened and loosened multiple times, the threads of internal threaded hole will gradually change slightly, which will affect the fastening performance of the connecting rod threaded connection pair, and in severe cases, it can lead to fatigue failure of the connecting rod. Compared to the external threads of bolts, the internal space of internal threads in connecting rod is narrow, causing the low controllability and the high detection difficulty, and the detection methods are limited. At present, the main method for detecting internal threaded holes in connecting rods is through endoscopic observation. This method is difficult to operate, has low detection accuracy, cannot collect data, and cannot perform automated detection, resulting in low detection efficiency. Therefore, it is necessary to design a detection device with higher detection accuracy and efficiency, suitable for detecting internal threaded holes in connecting rods. SUMMARY The present disclosure aims to provide a device for testing and analyzing thread deformation of an internal threaded hole in an engine connecting rod to solve the problems of low detection efficiency and low detection accuracy in the endoscopic observation method. In order to achieve the above objectives, the solution of the present disclosure is: a device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod, including a detection table, wherein the detection table is provided with a computer, a left fixture unit, a right fixture unit, and a detection unit; the left fixture unit includes a left fixture sleeve, a left lifting tray, and a left lifting pump for driving the left lifting tray, and the left fixture sleeve is installed on the left lifting tray; the right fixture unit includes a right fixture sleeve, a right mounting seat, a right lifting tray, and a right lifting pump for driving the right lifting tray; the right fixture sleeve is mounted on the right mounting seat, and the right lifting tray is provided with a first horizontal driving assembly for driving a horizontal sliding of the right mounting seat; the detection unit includes a detection lifting tray and a detection lifting pump for driving the detection lifting tray, and the detection lifting tray is provided with a transverse moving plate and a second horizontal driving assembly for driving the transverse moving plate to move; the transverse moving plate is provided with a longitudinal moving plate and a third horizontal driving assembly for driving the longitudinal moving plate to move, and the longitudinal moving plate is provided with a measuring assembly; the measuring assembly includes a shaft seat, a measuring tool shaft, and a driving motor for driving the measuring tool shaft to rotate, the shaft seat is provided with a threaded through-hole, and the threaded through-hole has the same specifications as the internal threaded hole in the connecting rod to be tested; the measuring tool shaft is connected to the threaded through-hole by threads, and the measuring tool shaft is provided with a first distance sensor and an image collector; a bottom of the driving motor is provided with a sliding plate, and the sliding plate is horizontally connected to the longitudinal moving plate; the computer is capable of obtaining distance information detected by the first distance sensor and image information collected by the image collector, so as to obtain a radial collapse amount of the threads based on the distance information, and obtain an axial deviation result of the threads based on the image information. The working principle and advantageous effects of this solution are as follows: in this solution, the left fixture unit and the right fixture unit are used to fix and lift the connecting rod to be tested: the left fixture sleeve is inserted into the hole in the small end of the connecting rod to be tested, the right fixture sleeve is inserted into the hole in the large end of the connecting rod to be tested, and the first horizontal driving assembly is used to make the right fixture sleeve have a tendency to move to the right, thereby tensioning the connecting rod to be tested and achieving the fixation of the connecting rod to be tested, then using the left lifting pump and the right lifting pump to lift the connecting rod to be tested. Afterwards, the detection unit is used to detect the connecting rod to be tested: the second horizontal driving assembly, the third horizontal driving assembly, and the detection lifting pump are used to move the measuring assembly, so that the measuring tool shaft is coaxial with the threaded hole inside the connecting rod to be tested; the measuring tool shaft is driven to rotate by the driving motor, since the threaded through-hole on the shaft seat has the same specification as the threaded hole inside the connecting rod to be tested, the measuring tool shaft rotates 360° when it advances or retreats by one pitch P; the image information is collected by the image collector on the measuring tool shaft and transmitted to the computer, the computer then compares the image information collected by the image collector on the measuring tool shaft with the image information collected when the connecting rod to be tested is not in use (the image information retained during the testing on the device when the connecting rod to be tested is not in use or when the connecting rod of the same specification is not in use), so as to obtain the axial deviation of the threaded hole in the connecting rod to be tested; afterwards, the second horizontal driving assembly drives the measuring tool shaft to retract. During the retraction process, the first distance sensor on the measuring tool shaft detects the distance information and transmits the distance information to the computer. The computer compares the distance information with the distance information detected when the connecting rod is not in use (the distance information retained during the testing on the device when the connecting rod is not in use or when the same specification connecting rod is not in use), so as to obtain the radial collapse amount of the threaded hole in the connecting rod, thereby completing the thread deformation detection of the threaded hole in the connecting rod, which realizes automated detection, improves detection efficiency and accuracy, and is easy to operate, clean and pollution-free, with good market application prospects. Further, a method for testing and analyzing thread deformation of internal threaded hole in engine connecting rod is also provided by the present disclosure. The method uses the device mentioned above, and the method includes the following steps: SI, inputting of parameters for the connecting rod to be tested: inputting the parameters of the connecting rod to be tested into the computer; S2, sample loading: fixing and lifting the connecting rod to be tested through the left fixture unit and the right fixture unit; S3, centring: aligning the measuring tool shaft with the internal threaded hole on one side of the connecting rod to be tested coaxially using the detection lifting pump, the second horizontal driving assembly, and the third horizontal driving assembly; S4, testing: the testing is divided into a rotation advance testing stage and a retraction testing stage, wherein in the rotation advance testing stage, the boundary line between the smooth section of the internal threaded hole and the threaded section of the internal threaded hole is used as the starting point, the measuring tool shaft is driven by the driving motor to rotate in, and for each pitch of rotation, the measuring tool shaft is stationary for the image collector to collect image information, the image collector transmits the collected image information to the computer, the computer numbers and saves the collected image information in sequence according to a receiving order of the image information, and fits all the collected image information into a single picture according to the numbering; in the retraction testing stage, the first distance sensor transmits the detected distance information to the computer, the computer selects the minimum distance value from the received distance information in the frequency band where the distance information decreases and then increases, and records as the distance data set B' (Bl1, B2', B3'... Bn'); S5, analysis: the computer compares the image fitted in step S4 with the reference image obtained from computer database using an unused connecting rod of the same specification as the one being tested as the test object, to obtain the axial deviation result of the threads; the computer subtracts the distance data set B'(B1', B2', B3'... Bn') obtained in step S4 from the distance data set B (Bl, B2, B3... Bn) obtained in the computer database using unused connecting rods of the same specifications as the one being tested as the test object, and the absolute value of the difference obtained is the radial collapse amount of the threads; S6, re-centring: aligning the measuring tool shaft with the internal threaded hole on the other side of the connecting rod to be tested coaxially using the second horizontal driving assembly, and the third horizontal driving assembly; S7, repeating steps S4 and S5 to test and analyze the internal threaded hole on the other side of the connecting rod to be tested; S8, reset and end the test: resetting the left fixture unit, the right fixture unit, and the detection unit, removing the connecting rod to be tested to end the test. In this solution, the computer fits the received image information into a single picture according to the numbering, and the fitting method is to overlap the latter image information with the previous image information, and the right image edge of the latter image information differs from the right image edge of the previous image information by one pitch P (the pitch P is the pitch of the internal threaded hole), and ensure that the uncovered part of the previous image information is on the right side of the image information. The image obtained by fitting in this way can be compared with the reference image obtained from the computer database using unused connecting rods of the same specifications as the connecting rod to be tested as the test object, which can be used for inspection personnel to observe and compare, and to preliminarily understand the threads morphology inside the threaded hole of the connecting rod to be tested. Further, the computer aligns the fitted image with the reference image (one in upper side and one in the lower side, with the right edge of the image aligned). When aligning the two images, the intersection lines between the smooth and threaded segments of the internal threaded holes in the two images are aligned, that is, the right roots of the first threads in the two images are aligned. Afterwards, the computer recognizes the crests of the first threads, the crests of the second threads,.......and the crests of the n-th threads in the two images, and calculates the lateral vertical distance between the crests of the first threads in the two images, which is the axial deviation of the first threads, and then calculates the axial deviation of the rest threads in the same way. The lateral vertical distance between the crests of the n-th threads in the two images is the axial deviation of the n-th threads. Therefore, this method can obtain the axial deviation and radial collapse of the threaded hole of the connecting rod to be tested during the in-and-out process of measuring the shaft, providing data support for the evaluation of connecting rod usage and improving the reliability of the evaluation of connecting rod usage. Optionally, the right fixture sleeve is provided with a second distance sensor, a groove is provided on the right fixture sleeve for installing the second distance sensor, and the computer is capable of obtaining distance information detected by the second distance sensor. In this solution, the second distance sensor is used to detect the distance between the right fixture sleeve and the left fixture sleeve, and the position of the right fixture sleeve is pre-adjusted by the computer so that the center distance between the left fixture sleeve and the right fixture sleeve is equal to the center distance between the hole in the large end and the hole in the small end of the connecting rod to be tested. Optionally, a light-supplementary lamp is provided at one end of the measuring tool shaft away from the driving motor. In this solution, the light-supplementary lamp on the measuring tool axis is used to fill the light inside the threaded hole of the connecting rod to be tested, so that the image information collected by the image collector is clearer. Optionally, a plurality of the left fixture sleeves are provided, the plurality of the left fixture sleeves are uniformly distributed along a circumference of the left lifting tray, and outer diameters of the plurality of the left fixture sleeves are different from each other; and the left lifting tray is rotatably connected to an output end of the left lifting pump. In this solution, the outer diameters of several left fixture sleeves are not the same, and the left lifting tray is rotationally connected to the output end of the left lifting pump. Therefore, by rotating the left lifting tray, the left fixture sleeve that matches the holes in large end and the small end of connecting rod can be found to fix the connecting rod to be tested. Optionally, the left fixture sleeve is detachably connected to the left lifting tray, and the right fixture sleeve is detachably connected to the right mounting seat. In this solution, both the left fixture sleeve and the right fixture sleeve can be replaced, thereby achieving the detection of the holes in the large end and the small end of connecting rods with different sizes. Optionally, the shaft seat is detachably connected to the longitudinal moving plate. In this solution, the shaft seat on the longitudinal moving plate can be replaced, allowing for the installation of threaded through holes of different specifications and the detection of internal threaded holes in connecting rods of different specifications. Optionally, the first distance sensor and the image collector are located on the same radial section of the measuring tool shaft, and an angle between the first distance sensor and the image collector is 180°. In this solution, the first distance sensor is set opposite to the image collector. When the first distance sensor detects the first thread of the threaded hole in the connecting rod, the driving motor drives the measuring tool shaft to rotate. For each pitch of the measuring tool shaft, the image collector collects an image once and transmits the collected image to the computer for storage, comparison, and calculation. Optionally, a top of the left fixture sleeve and a top of the right fixture sleeve are both machined with a 45° chamfer. In this solution, the 45° chamfer at the top of the left fixture sleeve and the right fixture sleeve facilitates the insertion of the connecting rod to be tested. Optionally, a bottom of the left fixture sleeve and a bottom of the right fixture sleeve are both provided with bolt rods, and the left lifting tray and the right mounting seat are both provided with threaded blind holes that match threads of the bolt rods. In this solution, the detachable connection between the left fixture sleeve and the right fixture sleeve is achieved through the thread matching between the bolt rods and the threaded blind holes. BRIEF DESCRIPTION OF THE DRAWINGS FIG. lisa front sectional view of a device for testing and analyzing thread deformation of an internal threaded hole in an engine connecting rod in embodiment 1 of the present disclosure; FIG. 2 is a top view of FIG. 1 (Computer is not shown); FIG. 3 is a schematic diagram of the structure of the left fixture sleeve and the right fixture sleeve in the embodiment 1 of the present disclosure; FIG. 4 is an enlarged view of portion A in FIG. 1; FIG. 5 is a perspective view of the shaft seat and the measuring tool shaft in the embodiment 1 of the present disclosure; FIG. 6 is a left side view of the left end of the measuring tool shaft in FIG. 4; FIG. 7 is a schematic diagram of the structure when the first distance sensor is inserted into the internal threaded hole; FIG. 8 is a schematic diagram of computer window display; FIG. 9 is a schematic diagram of the parameters of the engine connecting rod; FIG. 10 is a simplified comparison of the internal threaded hole of the engine connecting rod before and after use; FIG. 11 is a schematic diagram of the structure of the left fixture sleeve and the right fixture sleeve in embodiment 2 of the present disclosure; FIG. 12 is a schematic diagram of the structure when the first distance sensor detects distance information when the measuring tool shaft and the internal threaded hole of the connecting rod to be tested are not completely aligned in the embodiment 3 of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS A detailed illustration will be given below through specific implementation methods: The reference markings in the accompanying drawings of the specification include: detection table 1, placement slot 101, computer 2, left fixture sleeve 3, left lifting tray 4, left lifting pump 5, bearing 6, right fixture sleeve 7, right mounting seat 8, right lifting tray 9, right lifting pump 10, first horizontal driving assembly 11, bolt rod 12, detection lifting tray 13, detection lifting pump 14, transverse moving plate 15, second horizontal driving assembly 16, longitudinal moving plate 17, third horizontal driving assembly 18, ball screw pair 19, motor 20, shaft seat 21, measuring tool shaft 22, driving motor 23, first distance sensor 24, image collector 25, light-supplementary lamp 26, sliding plate 27, second distance sensor 28. Embodiment 1 This embodiment provides a device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod, as shown in FIG. 1 and FIG. 2. The device includes a detection table 1, which is provided with a computer 2, a left fixture unit, a right fixture unit, and a detection unit. The left fixture unit includes left fixture sleeves 3, a left lifting tray 4, and a left lifting pump 5 for driving the left lifting tray 4. The left fixture sleeve 3 is installed on the left lifting tray 4, and the number of left fixture sleeves 3 is several. Several left fixture sleeves 3 are evenly distributed along the circumference of the left lifting tray 4, and the outer diameters of the several left fixture sleeves 3 are not the same. In this embodiment, the number of left fixture sleeves 3 is eight. In addition, the left lifting tray 4 is rotatably connected to the output end of the left lifting pump 5. Specifically, the bottom surface of the left lifting tray 4 is rotatably connected to the output end of the left lifting pump 5 through a bearing 6. The right fixture unit includes a right fixture sleeve 7, a right mounting seat 8, a right lifting tray 9, and a right lifting pump 10 for driving the right lifting tray 9. The right fixture sleeve 7 is mounted on the right mounting seat 8, and the right lifting tray 9 is provided with a first horizontal driving assembly 11 for driving the right mounting seat 8 to slide horizontally. In this embodiment, the left fixture sleeve 3 can be disassembled and installed on the left lifting tray 4, and the right fixture sleeve 7 can be disassembled and installed on the right mounting seat 8. Specifically, as shown in FIG. 3, the bottom ends of the left fixture sleeve 3 and the right fixture sleeve 7 are integrally formed with bolt rods 12, and the left lifting tray 4 and the right mounting seat 8 are both provided with threaded blind holes matching with bolt rods 12. The top ends of the left fixture sleeve 3 and the right fixture sleeve 7 are both machined with a 45° chamfer, so that the user can easily insert the left fixture sleeve 3 and the right fixture sleeve 7 into the small end hole and big end hole of the connecting rod to be tested when placing it. The detection unit includes a detection lifting plate 13 and a detection lifting pump 14 for driving the detection lifting tray 13. The detection lifting tray 13 is provided with a lateral moving plate 15 and a second horizontal driving assembly 16 for driving the lateral moving plate 15 to move. The lateral moving plate 15 is provided with a longitudinal moving plate 17 and a third horizontal driving assembly 18 for driving the longitudinal moving plate 17 to move. In this embodiment, the first horizontal driving assembly 11, the second horizontal driving assembly 16, and the third horizontal driving assembly 18 all include a ball screw pair 19 and a motor 20 for for driving the screw of the ball screw pair 19 to rotate. The right mounting seat 8 is horizontally connected to the right lifting tray 9 through the sliding cooperation between the slider and the groove. The lateral moving plate 15 is horizontally connected to the detection lifting plate 13 through the sliding cooperation between the slider and the groove. The longitudinal moving plate 17 is horizontally connected to the lateral moving plate 15 through the sliding cooperation between the slider and the groove. The longitudinal moving plate 17 is provided with a measuring component, which includes a shaft seat 21, a measuring tool shaft 22, and a driving motor 23 for driving the measuring tool shaft 22 to rotate. The shaft seat 21 can be disassembled and installed on the longitudinal moving plate 17. In this embodiment, the shaft seat 21 is installed on the longitudinal moving plate 17 by bolts. As shown in FIGS. 4, 5, 6, and 7, the shaft seat 21 is provided with threaded through holes, which have the same specifications as the threaded holes in the connecting rod to be tested. The measuring tool shaft 22 is connected to the threaded through holes, and the left end of the measuring tool shaft 22 is provided with a first distance sensor 24, an image collector 25, and a light-supplementary lamp 26. The first distance sensor 24, the image collector 25, and the light-supplementary light 26 are located on the same radial section of the measuring tool shaft 22, and the angle between the first distance sensor 24 and the image collector 25 is 180 °; in this embodiment, the first distance sensor 24 is an ultra-sonic distance measurement sensor, and the image collector 25 is a CCD industrial camera; in addition, the light-supplementary light 26 is used for illumination to ensure clear images captured by the image collector 25. The bottom end of the driving motor 23 is fixedly connected to a sliding plate 27, which is horizontally slid and connected to a longitudinal moving plate. The computer 2 can obtain distance information detected by the first distance sensor 24 and image information collected by the image collector 25. There are placement slots 101 on the detection table 1 for the left fixture unit, the right fixture unit, and the detection unit to be inserted. The upper surfaces of the left lifting tray 4, the right mounting seat 8, and the detection lifting tray 13 are flush with the upper surface of the detection table 1. Establish a three-dimensional coordinate system with the upper surface of the detection table 1 as the horizontal plane, with the X-axis direction being the transverse direction of the upper surface of the detection table 1, the Y-axis direction being the longitudinal direction of the upper surface of the detection table 1, and the Z-axis direction being the direction perpendicular to the upper surface of the detection table 1. In addition, the length unit of the three-dimensional coordinate system is mm. A method for testing and analyzing thread deformation of internal threaded hole in engine connecting rod is also provided by the present embodiment. The method uses the device mentioned above, and the method includes the following steps: Step 1, inputting the parameters of the connecting rod to be tested: click 1 “Initialization” in the window of the computer 2 (as shown in FIG. 8) to ensure that the left fixture unit, the right fixture unit, and the detection unit are in their initial positions. At this time, the coordinates of the left end axis center of the measuring tool shaft 22 are (X=0, Y=0, Z=200). It should be noted that this embodiment is only an example of this coordinate. In other embodiments, the Z-axis position of the left end axis center of the measuring tool shaft 22 can be 250, 260, 300, etc., and can be adjusted by the detection lifting pump 14. Input the parameters of the connecting rod to be tested into the computer 2, wherein the parameters includes the diameter DI of the small end of the connecting rod to be tested, the diameter D2 of the large end of the connecting rod to be tested, the center distance L of the connecting rod, the thickness 5 of the connecting rod, the distance d from the center of the large end of the connecting rod to the center of the bolt hole, and the pitch P of the internal thread, as shown in FIG. 9. After inputting the connecting rod parameters, click “Next”, and the computer 2 starts self checking to determine whether the pitch P of the internal threaded hole of the connecting rod to be tested is equal to the pitch of the internal threaded hole on the shaft seat 21, if not, replace the shaft seat 21 and the measuring tool shaft 22; determine whether the diameter DI of the small end of the connecting rod to be tested is the same as the outer diameter of the left fixture sleeve 3, and whether the diameter D2 of the large end of the connecting rod to be tested is the same as the outer diameter of the right fixture sleeve 7, if not, replace the left fixture sleeve 3 and the right fixture sleeve 7. It should be noted that the thread pitch of the threaded through-hole of the shaft seat 21, the outer diameters of the right fixture sleeve 7 and the left fixture sleeve 3 are all pre-entered and saved in the database of the computer 2, and can be called when needed. Moreover, whenever the shaft seat 21, the left fixture sleeve 3, and the right fixture sleeve 7 are replaced, simply re-enter the corresponding thread pitch of the threaded through-hole of the shaft seat 21 and the outer diameters of the right fixture sleeve 7 and left fixture sleeve 3. In addition, since there are eight of the left fixture sleeves 3, the computer 2 determines whether there are some that meet the conditions from the eight left fixture sleeves 3. The operator needs to manually rotate the left lifting tray 4 to move the eligible left fixture sleeves 3 to the position closest to the right fixture sleeve 7. Step 2, sample loading: the first horizontal driving assembly 11 works to adjust the position of the right fixture sleeve 7, so that the center distance between the right fixture sleeve 7 and the corresponding left fixture sleeve 3 is equal to L; afterwards, the testing personnel aligned the hole in the small end of the connecting rod to be tested with the left fixture sleeve 3, and aligned the hole in the large end of the connecting rod to be tested with the right fixture sleeve 7, so as to lower the connecting rod to be tested and insert the left fixture sleeve 3 and the right fixture sleeve 7 into the hole in the small end and the hole in the large end of the connecting rod to be tested, respectively. Subsequently, the first horizontal driving assembly 11 drives the right mounting seat 8 to have a tendency to move to the right, thereby tensioning and fixing the connecting rod to be tested. At this time, the center line between the right fixture sleeve 7 and the left fixture sleeve 3 inserted into the hole in the small end of the connecting rod to be tested coincides with the X-axis. Next, the computer 2 controls yjr left lifting pump 5 and the right lifting pump 10 to work simultaneously, causing the left lifting tray and the right mounting seat 8 to rise synchronously by (200- 5 / 2) mm, at this time, the center point of the starting position of the internal threaded hole of the connecting rod to be tested has coordinates of - d on the Y-axis and 200 on the Z-axis. Step 3, centring: since the coordinates of the left end axis center of the measuring tool shaft 22 on the Z-axis are the same as the coordinates of the center point of the initial position of the internal threaded hole in the connecting rod to be tested on the Z-axis (both are Z=200), the detection lifting pump 14 no longer adjusts the height of the measuring tool shaft 22. The computer 2 directly controls the second horizontal driving assembly 16 and the third horizontal driving assembly 18 to work: the third horizontal driving assembly 18 drives the longitudinal moving plate 17 to move in the negative direction of Y-axis, and the second horizontal driving assembly 16 drives the transverse moving plate 15 to move in the negative direction of X-axis, so that the coordinates of the left end axis center of the measuring tool shaft 22 become (X=-580+L, Y=- d, Z=200), that is to say, the measuring tool shaft 22 is coaxial with the internal threaded hole of the connecting rod to be tested. S4, testing: the testing is divided into a rotation advance testing stage and a retraction testing stage, wherein in the rotation advance testing stage. Before entering the rotation advance testing stage, the computer 2 controls the second horizontal driving assembly 16 to work, so as to move the measuring assembly to the left, causing the left end of the measuring tool shaft 22 to enter the internal threaded hole. The internal threaded hole has a smooth section and a threaded section. Therefore, the distance information detected by the first distance sensor 24 has a stable value, and then gradually decreases and then gradually increases (when encountering a thread). When the distance information detected by the first distance sensor 24 decreases, the second horizontal driving assembly 16 drives the measuring assembly to retreat to the right, causing the first distance sensor 24 to retreat to the intersection point between the stable value and the value started to decrease. The boundary line between the smooth section and the threaded section is found and used as the starting point, entering the rotation advance testing stage: the measuring tool shaft 22 is driven by the driving motor 23 to move to the left (during which the driving motor 23 and the sliding plate 27 move to the left on the longitudinal moving plate 17), and the image collector 25 collects image information of the internal threaded hole. For each pitch P of rotation forward, the measuring tool shaft 22 remains stationary for 2 seconds (the stationary time can be set to other values) so that the image collector 25 can collect image information. The image collector 25 transmits the image information to the computer 2, and the computer 2 sequentially numbers and saves the image information according to the receiving order until the distance information detected by the first distance sensor 24 suddenly becomes large (i.e., the first distance sensor 24 passes through the internal threaded hole), completing the image acquisition work. For ease of description, after the measuring tool shaft 22 rotates forward into the first pitch P, the image received by the computer 2 is Al'. After the measuring tool shaft 22 rotates forward into the second pitch P, the image received by the computer 2 is A'..., after the measuring tool shaft 22 rotates forward into the n-th pitch P, the image received by the computer 2 is An'. The computer 2 fits all the image information into one image according to the numbering, which is the fitted image A'. The fitting method is as follows: overlap the image A2' on the image Al', and the right image edge of the image A2' differs from the right image edge of the image Al' by one pitch P, ensuring that the uncovered part of Al' is on the right side of the image. Then overlap A3' on A2', and the right image edge of the image A3' differs from the right image edge of the image A2' by one pitch P, ensuring that the uncovered part of A2' is on the right side of the image. Repeat this process until An' is overlapped on A(n-l)', and the right image edge of the image An' differs from the right image edge of the image A(n-l)' by one pitch P, ensuring that the uncovered part of A (n-1)' is on the right side of the image to complete the fitting, so as to obtain the fitted image A'. During the rotation advance testing stage, the second horizontal drive assembly 16 is not working. After the first distance sensor 24 passes through the internal threaded hole, the driving motor 23 stops working and enters the retraction test stage: the second horizontal driving assembly 16 drives the measuring assembly to retract and reset to the right (the coordinates of the left end axis center of the measuring tool shaft 22 return to (X=-580+L, Y=- d, Z=200)). During the process, the first distance sensor 24 detects the distance information between the detection end of the first distance sensor 24 and the internal threaded hole. When the first distance sensor 24 is aligned with the root of the thread, the distance is the maximum value (limited to the internal threaded hole), and when the first distance sensor 24 is aligned with the crest of the thread, the distance is the minimum value (limited to the internal threaded hole). Therefore, the computer 2 obtains the distance between the detection end of the first distance sensor 24 and each thread crest of the internal threaded hole through the first distance sensor 24. More specifically, the computer 2 selects the minimum distance value from the received numerous distance information in the frequency band where the distance information decreases and then increases, and records them as the distance data set B' (Bl', B2', B3'... Bn'). Bl' refers to the distance between the crest of the first thread and the detection end of the first distance sensor 24, similarly, Bn' refers to the distance between the crest of the n-th thread and the detection end of the first distance sensor 24, and the first one refers to the first internal threaded hole counted from left to right. Step 5, analysis: the computer 2 compares the fitted image A' obtained in step 4 with the reference image A obtained from the database of the computer 2 using an unused connecting rod of the same specification as the one being tested (tested according to this method), to obtain the result of axial deviation of the threads. Specifically, the computer 2 aligns the fitted image A' with the reference image A (one in upper side and one in the lower side, with the right edge of the image aligned). When aligning the two images, the intersection line between the smooth section and the threaded section of the internal threaded hole in the two images is aligned, that is, the right roots of the first threads in the two images are aligned. Afterwards, the computer 2 respectively recognizes the crest of the first thread, the crest of the second thread, and the n-th thread in each of the two images, and calculates the lateral vertical distance between the crests of the first threads in the two images, which is the axial deviation AL1 of the first threads, similarly, the lateral vertical distance between the crests of the n-th threads in the two images is the axial deviation ALn of the n-th thread. In the rotation advance test phase, the first thread refers to the first thread of the internal threaded hole counted from right to left. In addition, the computer 2 subtracts the distance data set B' (Bl1, B2', B3'... Bn') obtained in step 4 from the distance data set B (Bl, B2, B3... Bn) obtained in the database of the computer 2 using unused connecting rods of the same specification as the one being tested (tested according to this method), and the absolute value of the difference obtained is the radial collapse amount of the threads. Specifically, the computer 2 takes Bl and Bl' into formula Bl' - Bl to calculate the difference AX1, which is the radial collapse amount of the first thread. Similarly, the computer 2 takes Bn and Bn' into formula Bn' - Bn to calculate the difference AXn, which is the radial collapse amount of the n-th thread. In the retraction testing stage, the first thread refers to the first thread of the internal threaded hole counted from left to right. The calculation method for the axial deviation A L of the thread and the radial collapse A X of the thread are shown in FIG. 10. In FIG. 10, the dashed line represents the morphology of the internal threaded hole when the connecting rod is not in use, and the solid line represents the morphology of the internal threaded hole after a period of use of the connecting rod. Step 6: re-centring: the computer 2 controls the second horizontal driving assembly 16 and the third horizontal driving assembly 18 to align the measuring tool shaft 22 with the internal threaded hole on the other side of the connecting rod to be tested coaxially. Specifically, the second horizontal driving assembly drives the transverse moving plate 15 to move in the positive direction of X-axis, so that the coordinates of the left end axis center of the measuring tool shaft 22 are (X=0, Y=-d, Z=200); The third horizontal driving assembly 18 drives the longitudinal moving plate 17 to move in the positive direction of Y-axis, so that the coordinates of the left end axis center of the measuring tool shaft 22 are (X=0, Y=d, Z=200); the second horizontal driving assembly 16 drives the transverse moving plate 15 to move in the negative direction of X-axis again, so that the coordinates of the left end axis center of the measuring tool shaft 22 are (X=-580+L, Y=d, Z=200), so that the measuring tool shaft 22 is aligned with the internal threaded hole on the other side of the connecting rod to be tested. S7, repeating steps S4 and S5 to test and analyze the internal threaded hole on the other side of the connecting rod to be tested. S8, reset and end the test: the computer 2 controls the left fixture unit, the right fixture unit, and the detection unit to reset, the operator removes the connecting rod to be tested from the left fixture sleeve 3 and the right fixture sleeve 7 to end the test. In summary, in this embodiment, the image information of the internal threaded hole is collected by the image collector 25 during the leftward rotation advance movement of the measuring tool shaft 22. During the rightward translation and retraction (without rotation) of the measuring tool shaft 22, the distance information between each thread of the internal threaded hole and the detection end of the first distance sensor 24 is detected by the first distance sensor 24, thereby obtaining the axial deviation and radial collapse of each thread of the internal threaded hole. This achieves automatic detection of thread deformation of the internal threaded hole in the connecting rod, improves detection efficiency and accuracy, and is conducive to accurately evaluating the use of the connecting rod, providing data support for determining whether the connecting rod can continue to be used. By fitting image A', the color and degree of corrosion and rust of the threaded hole inside the connecting rod to be tested can be observed, thus better evaluating the usage of the connecting rod to be tested. Embodiment 2 The difference between this embodiment and embodiment 1 is that, as shown in FIG. 11, in this embodiment, a second distance sensor 28 is provided on the right fixture sleeve 7, and a groove is provided on the right fixture sleeve 7 for installing the second distance sensor 28. The second distance sensor 28 in this embodiment is a laser distance sensor, and the second distance sensor 28 transmits the detected distance information to the computer 2. In this embodiment, the second distance sensor 28 detects the distance between the right fixture sleeve 7 and the appropriate left fixture sleeve 3, and transmits the distance data to the computer 2. The computer 2 determines whether the distance data is equal to L - (Dl / 2) - (D2 / 2). When they are equal, the computer 2 controls the first horizontal driving assembly 11 to stop working, which is simple to operate and does not require manual control of the first horizontal driving assembly 11 to adjust the distance between the right fixture sleeve 7 and the appropriate left fixture sleeve 3. Embodiment 3 The difference between this embodiment and either embodiment 1 or embodiment 2 is that: Step three in this embodiment is different from step 3 in either embodiment 2 or embodiment 1. Specifically, step 3 in this embodiment is as follows: Step 3, centring: since the coordinates of the left end axis center of the measuring tool shaft 22 on the Z-axis are the same as the coordinates of the center point of the initial position of the threaded hole in the connecting rod to be tested on the Z-axis (both are Z=200), the detection lifting pump 14 no longer adjusts the height of the measuring tool shaft 22. The computer 2 directly controls the second horizontal driving assembly 16 and the third horizontal driving assembly 18 to work: the third horizontal driving assembly 18 drives the longitudinal moving plate 17 to move in the negative direction of Y-axis, and the second horizontal driving assembly 16 drives the transverse moving plate 15 to move in the negative direction of X-axis, so that the coordinates of the left end axis center of the measuring tool shaft 22 become (X=-580+L, Y=-d, Z=200), that is to say, the measuring tool shaft 22 is aligned coaxially with the internal threaded hole of the connecting rod to be tested preliminarily. Subsequently, the computer 2 controls the second horizontal driving assembly 16 to operate, causing the measuring assembly to move to the left. The left end of the measuring tool shaft 22 enters the internal threaded hole, which has a smooth and threaded section. Therefore, the distance information detected by the first distance sensor 24 has a stable value, then gradually decreases and then gradually increases (when encountering a thread). When the distance information detected by the first distance sensor 24 decreases, the second horizontal driving assembly 16 drives the measuring assembly to retreat to the right to the starting point wherein the stable value is detected. Afterwards, in order to improve the centering degree, the driving motor 23 drives the measuring tool shaft 22 to rotate, and the measuring assembly rotates to the left. The first distance sensor 24 collects distance information every 90° of rotation and transmits the collected distance information to the computer 2. Every four parameters form one cycle, represented as (270°: e, 0°: f, 90°: g, 180°: h), as shown in FIG. 12 (the dashed line in FIG. 12 represents the orientation of 0°, 90°, and 180° when the first distance sensor 24 rotates forward). The computer 2 adjusts the coordinates of the left end axis center of the measuring tool shaft 22 based on the received distance information as (X'=X, Y'=Y-[((f+h) / 2) - f], Z'=Z-[((g+e) / 2) - g]. The values of e, f, g, and h are re-taken in each cycle (for each pitch P screwed in) until |e-g| <0.001 and |f-h| <0.001, then stop the cycle to ensure that the measuring tool shaft 22 is centred coaxially in the internal threaded hole. The above are only embodiments of the present disclosure, and the disclosure is not limited to the field involved in these embodiments. The specific structures and characteristics known in the solution are not described in detail here. Ordinary skilled person in the art are aware of all the ordinary technical knowledge in the technical field to which the disclosure belongs before the application date or priority date, and can know all the existing technologies in this field, and have the ability to apply conventional experimental methods before that date. Ordinary skilled person in the art can improve and implement this solution based on their own abilities under the inspiration given in this application. Some typical known structures or methods should not be obstacles for ordinary skilled person in the art to implement this application. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present disclosure, which should also be considered as the scope of the present disclosure. These will not affect the effectiveness and practicality of the present disclosure. The scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification may be used to interpret the content of the claims.

Claims

1. A device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod, comprising a detection table, characterized in that: the detection table is provided with a computer, a left fixture unit, a right fixture unit, and a detection unit; the left fixture unit comprises a left fixture sleeve, a left lifting tray, and a left lifting pump for driving the left lifting tray, and the left fixture sleeve is installed on the left lifting tray; the right fixture unit comprises a right fixture sleeve, a right mounting seat, a right lifting tray, and a right lifting pump for driving the right lifting tray; the right fixture sleeve is mounted on the right mounting seat, and the right lifting tray is provided with a first horizontal driving assembly for driving a horizontal sliding of the right mounting seat; the detection unit comprises a detection lifting tray and a detection lifting pump for driving the detection lifting tray, and the detection lifting tray is provided with a transverse moving plate and a second horizontal driving assembly for driving the transverse moving plate to move; the transverse moving plate is provided with a longitudinal moving plate and a third horizontal driving assembly for driving the longitudinal moving plate to move, and the longitudinal moving plate is provided with a measuring assembly; the measuring assembly comprises a shaft seat, a measuring tool shaft, and a driving motor for driving the measuring tool shaft to rotate, the shaft seat is provided with a threaded through-hole, and the threaded through-hole has the same specifications as the internal threaded hole in the connecting rod to be tested; the measuring tool shaft is connected to the threaded through-hole by threads, and the measuring tool shaft is provided with a first distance sensor and an image collector; a bottom of the driving motor is provided with a sliding plate, and the sliding plate is horizontally connected to the longitudinal moving plate; the computer is capable of obtaining distance information detected by the first distance sensor and image information collected by the image collector, so as to obtain a radial collapse amount of the threads based on the distance information, and obtain an axial deviation result of the threads based on the image information.

2. The device for testing and analyzing thread deformation of internal threaded hole inengine connecting rod according to claim 1, characterized in that the right fixture sleeve is provided with a second distance sensor, a groove is provided on the right fixture sleeve for installing the second distance sensor, and the computer is capable of obtaining distance information detected by the second distance sensor.

3. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 1, characterized in that a light-supplementary lamp is provided at one end of the measuring tool shaft away from the driving motor.

4. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod to claim 1, characterized in that a plurality of the left fixture sleeves are provided, the plurality of the left fixture sleeves are uniformly distributed along a circumference of the left lifting tray, and outer diameters of the plurality of the left fixture sleeves are different from each other; and the left lifting tray is rotatably connected to an output end of the left lifting pump.

5. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 1, characterized in that the left fixture sleeve is detachably connected to the left lifting tray, and the right fixture sleeve is detachably connected to the right mounting seat.

6. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 1, characterized in that the shaft seat is detachably connected to the longitudinal moving plate.

7. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 1, characterized in that the first distance sensor and the image collector are located on the same radial section of the measuring tool shaft, and an angle between the first distance sensor and the image collector is 180°.

8. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 1, characterized in that a top of the left fixture sleeve and a top of the right fixture sleeve are both machined with a 45° chamfer.

9. The device for testing and analyzing thread deformation of internal threaded hole in engine connecting rod according to claim 5, characterized in that a bottom of the left fixture sleeveand a bottom of the right fixture sleeve are both provided with bolt rods, and the left lifting tray and the right mounting seat are both provided with threaded blind holes that match threads of the bolt rods.

10. A method for testing and analyzing thread deformation of internal threaded hole in engine connecting rod, characterized in that, the method uses the device according to any one of claims 1-9, and the method comprises the following steps:SI, inputting of parameters for the connecting rod to be tested: inputting the parameters of the connecting rod to be tested into the computer;S2, sample loading: fixing and lifting the connecting rod to be tested through the left fixture unit and the right fixture unit;S3, centring: aligning the measuring tool shaft with the internal threaded hole on one side of the connecting rod to be tested coaxially using the detection lifting pump, the second horizontal driving assembly, and the third horizontal driving assembly;S4, testing: the testing is divided into a rotation advance testing stage and a retraction testing stage, wherein in the rotation advance testing stage, the boundary line between the smooth section of the internal threaded hole and the threaded section of the internal threaded hole is used as the starting point, the measuring tool shaft is driven by the driving motor to rotate in, and for each pitch of rotation, the measuring tool shaft is stationary for the image collector to collect image information, the image collector transmits the collected image information to the computer, the computer numbers and saves the collected image information in sequence according to a receiving order of the image information, and fits all the collected image information into a single picture according to the numbering; in the retraction testing stage, the first distance sensor transmits the detected distance information to the computer, the computer selects the minimum distance value from the received distance information in the frequency band where the distance information decreases and then increases, and records as the distance data set B' (Bl1, B2', B3'... Bn');S5, analysis: the computer compares the image fitted in step S4 with the reference image obtained from computer database using an unused connecting rod of the same specification as the one being tested as the test object, to obtain the axial deviation result of the threads; the computersubtracts the distance data set B2', B3'... Bn') obtained in step S4 from the distance data set B (Bl, B2, B3... Bn) obtained in the computer database using unused connecting rods of the same specifications as the one being tested as the test object, and the absolute value of the difference obtained is the radial collapse amount of the threads;S6, re-centring: aligning the measuring tool shaft with the internal threaded hole on the other side of the connecting rod to be tested coaxially using the second horizontal driving assembly, and the third horizontal driving assembly;S7, repeating steps S4 and S5 to test and analyze the internal threaded hole on the other side of the connecting rod to be tested;S8, reset and end the test: resetting the left fixture unit, the right fixture unit, and the detection unit, removing the connecting rod to be tested to end the test.

Images