Threaded connection gap vision measurement device and measurement method

Abstract

The invention belongs to the technical field of assembly and detection of mechanical parts, and aims to solve the problems of large measurement error and low efficiency when a filler gauge is used for measuring a threaded connection gap in a manual manner. The invention provides a threaded connection gap vision measurement device and method. The device comprises a measured part, a radial limiting mechanism, a circumferential rotating mechanism, a vision measurement mechanism and a measurement table. The periphery of the tested part is provided with a threaded connection gap; the radial limiting mechanism sleeves the circumference of the outer wall of the tested part; the rotating surface of the circumferential rotating mechanism is in fit transmission with the periphery of the tested part; a visual mechanism of the visual measurement mechanism points to the position of the threaded connection gap of the measured part and is used for obtaining image information of the threaded connection gap, and an image analysis system of the visual measurement mechanism is used for obtaining the image information of the threaded connection gap and analyzing size data of the threaded connection gap. According to the invention, accurate measurement of the threaded connection gap can be realized through visual measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical parts assembly detection, and in particular relates to a threaded connection gap visual measurement device and a measurement method. Background Art

[0002] Threaded connection is the most common connection method in the engineering field. Its performance is directly related to the quality and safety of the product. About 60% of the parts of modern machines are made of threads. However, threaded connection inevitably has connection gap problems, which will affect the tightness and stability of the connection and may even cause product failure.

[0003] At present, there has been no convenient and effective detection solution for the specific size of threaded connection gaps. When measuring gaps, inspectors generally use feeler gauges to measure manually, which has problems such as large measurement errors, time-consuming and labor-intensive measurement processes, high costs, and low efficiency. With the full automation and intelligent development of industrial production processes, traditional measurement methods can no longer meet the needs of actual production. Especially in the field of high-precision manufacturing, traditional tools cannot achieve the required accuracy level for the detection of tiny size and shape errors. Summary of the invention

[0004] In order to solve at least one of the above-mentioned technical problems existing in the prior art, the present invention provides a visual measurement device and a measurement method for threaded connection gaps.

[0005] The present invention is implemented by the following technical scheme: a visual measurement device for threaded connection gap, comprising a measured part, a radial limiting mechanism, a circumferential rotation mechanism, a visual measurement mechanism and a measuring platform; the circumference of the measured part is provided with a threaded connection gap; the radial limiting mechanism is sleeved at the circumference of the outer wall of the measured part, for preventing the measured part from radially offset during axial rotation; the rotating surface of the circumferential rotation mechanism is in contact with the outer circumference of the measured part for transmission, for driving the measured part to rotate circumferentially, wherein the circumferential rotation takes the central axis of the measured part as the rotating axis; the visual mechanism of the visual measurement mechanism points to the threaded connection gap position of the measured part, for obtaining image information at the threaded connection gap, and the image analysis system of the visual measurement mechanism obtains the size data of the threaded connection gap based on the image information at the threaded connection gap; the radial limiting mechanism, the circumferential rotation mechanism and the visual measurement mechanism are all arranged at the upper end of the measuring platform.

[0006] Preferably, the radial limiting mechanism includes an annular member and a bracket. The annular member is circumferentially sleeved on the circumference of the outer wall of the measured part, and includes an upper half ring and a lower half ring connected by bolts. The bracket is connected between the annular member and the measuring platform, and the radial limiting mechanism avoids the threaded connection gap position of the measured part.

[0007] Preferably, the circumferential rotation mechanism includes a shaft end drive mechanism and two shaft end transmission mechanisms, the two shaft end transmission mechanisms are respectively located on both sides of the shaft end of the measured part, and the rotating surfaces of the two shaft end transmission mechanisms are in contact with the outer circumference of the measured part for transmission; the shaft end drive mechanism is connected to one of the shaft end transmission mechanisms through a pulley drive.

[0008] Preferably, the shaft end transmission mechanism includes a first synchronous pulley, a first cylindrical roller, a first roller shaft and a first bearing seat, the first roller shaft is rotatably connected to the first bearing seat through a bearing, and the first synchronous pulley and the first cylindrical roller are both keyed to the first roller shaft; the shaft end drive mechanism includes a shaft end power source, a second synchronous pulley and a belt, the output end of the shaft end power source arranged at the upper end of the measuring platform is connected to the second synchronous pulley, and the second synchronous pulley is connected to one of the first synchronous pulleys through a belt.

[0009] Preferably, an end baffle is provided on the measuring platform at one end of the measured part away from the circumferential rotation mechanism, and an end baffle wheel is provided on the end surface of the measured part close to the measured part, and the end baffle wheel is used to limit the axial lateral displacement of the measured part.

[0010] Preferably, a guide rail and an auxiliary shaft-side limiting mechanism are provided on the measuring platform. The guide rail is arranged on the inner side of the upper end of the measuring platform close to the shaft-end baffle and is arranged along the axial direction of the measured part. The auxiliary shaft-side limiting mechanism is slidably connected to the guide rail and can fix the positions of the two through a locking member. The auxiliary shaft-side limiting mechanism is used for radial auxiliary limiting of the side of the measured part away from the shaft-end transmission mechanism.

[0011] Preferably, the shaft-side auxiliary limiting mechanism includes two single-sided limiting mechanisms and a connecting base plate, the single-sided limiting mechanism includes a second cylindrical roller, a second roller shaft and a second bearing seat, the second roller shaft is rotatably connected to the second bearing seat through a bearing, the second cylindrical roller is connected to the second roller shaft, and the second cylindrical roller is in fit transmission with the outer periphery of the measured part; the two single-sided limiting mechanisms are connected through a connecting base plate and are respectively located on both sides of the measured part, and the bottom of the connecting base plate has a pulley that slides with the slide rail and a hole connected with the slide rail bolt.

[0012] Preferably, the radial limiting mechanism is arranged in the middle part of the measuring platform, and an elastic supporting wheel is arranged near the radial limiting mechanism. The wheel surface of the elastic supporting wheel is arranged to fit the measured part. The elastic supporting wheel is used to reduce the up and down vibration of the measured part during rotation. An adjusting foot cup is arranged at the bottom end of the measuring platform.

[0013] Preferably, the visual measurement mechanism includes a three-axis mobile platform, an image analysis system and a visual mechanism consisting of an industrial camera, a matching lens and a ring light source. The visual mechanism is installed on the three-axis mobile platform, the three-axis mobile platform is installed on the upper end of the measuring platform and can drive the matching lens in the visual mechanism to align with the threaded connection gap of the measured part by adjusting the movement in the X-axis, Y-axis and Z-axis directions. The industrial camera is connected to the three-axis mobile platform through a camera frame, the matching lens is connected to the industrial camera and is positioned at the camera frame with the assistance of a buckle, the ring light source is located at the front end of the matching lens and is connected to the camera frame through a light source frame, and the image analysis system is electrically connected to the industrial camera.

[0014] The present invention also provides a method for visually measuring a threaded connection gap, comprising the following steps:

[0015] The measured part, radial limit mechanism, circumferential rotation mechanism and visual measurement mechanism are all installed on the upper end of the measuring table; the position of the matching lens on the three-axis moving table is adjusted so that it faces the threaded connection gap of the measured part, and the distance between the matching lens and the threaded connection gap is adjusted at the same time; the distance is obtained based on the calibration of the measured parts of different diameters by the industrial camera; the power source at the end of the shaft is controlled to drive the measured part to rotate at a uniform speed, and the industrial camera takes a picture every time the measured part rotates through a predetermined angle until the measured part completes a full rotation; the image analysis system receives the image information transmitted by the industrial camera and obtains the size data of the threaded connection gap.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention can achieve accurate measurement of threaded connection gaps through a visual measurement mechanism, thereby timely discovering problems and making adjustments, effectively improving the quality and stability of threaded connections, reducing the risk of product failure, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is the overall structural diagram of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the shaft end baffle of the present invention;

[0021] Figure 3 It is a structural schematic diagram of the shaft end transmission mechanism of the present invention;

[0022] Figure 4 It is a structural schematic diagram of the radial limiting mechanism in the present invention;

[0023] Figure 5 It is a structural schematic diagram of the guide rail and the shaft side auxiliary limiting mechanism in the present invention;

[0024] Figure 6 It is a schematic diagram of the structure of the elastic support wheel in the present invention;

[0025] Figure 7 It is a schematic diagram of the structure of the adjusting foot cup in the present invention;

[0026] Figure 8 It is a structural schematic diagram of the shaft end drive mechanism of the present invention;

[0027] Fig. 9 It is a structural schematic diagram of the visual measurement mechanism in the present invention;

[0028] Fig.10 It is a structural schematic diagram of the visual mechanism in the present invention;

[0029] Fig.11 It is a conversion relationship diagram between the world coordinate system and the camera coordinate system in the present invention.

[0030] In the figure: 1-part to be measured; 2.1-annular part; 2.2-bracket; 3.1-first synchronous pulley; 3.2-first cylindrical roller; 3.3-first roller axle; 3.4-first bearing seat; 3.5-shaft end power source; 3.6-second synchronous pulley; 3.7-belt; 4.1-three-axis moving table; 4.2-industrial camera; 4.3-matching lens; 4.4-annular light source; 5-measuring table; 6.1-shaft end baffle; 6.2-shaft end baffle wheel; 7.1-guide rail; 7.2-connecting bottom plate; 7.3-second cylindrical roller; 7.4-second roller axle; 7.5-second bearing seat; 8-elastic support wheel; 9-adjusting foot cup. DETAILED DESCRIPTION

[0031] In conjunction with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention. It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0033] The present invention provides an embodiment:

[0034] like Figures 1 to 11 As shown, a visual measurement device for threaded connection gaps comprises a measured part 1, a radial limiting mechanism, a circumferential rotation mechanism, a visual measurement mechanism and a measuring table 5; the circumference of the measured part 1 is provided with a threaded connection gap; the radial limiting mechanism is sleeved on the circumference of the outer wall of the measured part 1, for preventing the measured part 1 from radially deviating during axial rotation; the rotating surface of the circumferential rotation mechanism is in contact with the outer circumference of the measured part 1 for transmission, for driving the measured part 1 to perform axial rotation, and the circumferential rotation takes the central axis of the measured part 1 as the rotation axis; the visual mechanism of the visual measurement mechanism points to the position of the threaded connection gap of the measured part 1, for obtaining image information at the threaded connection gap, and the image analysis system of the visual measurement mechanism obtains the size data of the threaded connection gap based on the image information at the threaded connection gap; the radial limiting mechanism, the circumferential rotation mechanism and the visual measurement mechanism are all arranged at the upper end of the measuring table 5.

[0035] In this embodiment, the radial limiting mechanism includes a ring member 2.1 and a bracket 2.2. The ring member 2.1 is circumferentially sleeved on the circumference of the outer wall of the measured part 1, and includes an upper half ring and a lower half ring connected by bolts, so as to ensure that the center position of the measured part does not shift during the rotation. The bracket 2.2 is connected between the ring member 2.1 and the measuring table 5, and the radial limiting mechanism avoids the threaded connection gap position of the measured part 1.

[0036] The circumferential rotation mechanism includes a shaft end drive mechanism and two shaft end transmission mechanisms. The two shaft end transmission mechanisms are respectively located on both sides of the shaft end of the measured part 1, and the rotating surfaces of the two shaft end transmission mechanisms are in contact with the outer periphery of the measured part 1 for transmission. The shaft end drive mechanism is connected to one of the shaft end transmission mechanisms through a pulley transmission. The shaft end transmission mechanism includes a first synchronous pulley 3.1, a first cylindrical roller 3.2, a first roller shaft 3.3 and a first bearing seat 3.4. The first roller shaft 3.3 is rotatably connected to the first bearing seat 3.4 through a bearing. The first synchronous pulley 3.1 and the first cylindrical roller 3.2 are both key-connected to the first roller shaft 3.3. The shaft end drive mechanism includes a shaft end power source 3.5, a second synchronous pulley 3.6 and a belt 3.7. The output end of the shaft end power source 3.5 arranged at the upper end of the measuring platform 5 is connected to the second synchronous pulley 3.6, and the second synchronous pulley 3.6 is connected to one of the first synchronous pulleys 3.1 through a belt 3.7.

[0037] An end baffle 6.1 is provided on the measuring table 5 at the end of the measured part 1 away from the circumferential rotation mechanism, and an end baffle wheel 6.2 is provided on the end surface of the shaft end baffle 6.1 close to the measured part 1. The shaft end baffle wheel 6.2 is used to limit the axial lateral movement of the measured part 1.

[0038] A guide rail 7.1 and an auxiliary shaft-side limiting mechanism are provided on the measuring table 5. The guide rail 7.1 is arranged at a position on the inner side of the shaft-end baffle 6.1 at the upper end of the measuring table 5 and is arranged along the axial direction of the measured part 1. The auxiliary shaft-side limiting mechanism is slidably connected to the guide rail 7.1 and can fix the positions of the two through a locking member. The auxiliary shaft-side limiting mechanism is used for radial auxiliary limiting of the side of the measured part 1 away from the shaft-end transmission mechanism.

[0039] The shaft-side auxiliary limiting mechanism includes two single-sided limiting mechanisms and a connecting base plate 7.2. The single-sided limiting mechanism includes a second cylindrical roller 7.3, a second roller shaft 7.4 and a second bearing seat 7.5. The second roller shaft 7.4 is rotatably connected to the second bearing seat 7.5 through a bearing. The second cylindrical roller 7.3 is connected to the second roller shaft 7.4. The second cylindrical roller 7.3 is in contact with the outer periphery of the measured part 1 for transmission. The two single-sided limiting mechanisms are connected through the connecting base plate 7.2 and are respectively located on both sides of the measured part 1. The bottom of the connecting base plate 7.2 has a pulley that slides with the slide rail 7.1 and a hole that is bolted to the slide rail 7.1.

[0040] A radial limiting mechanism is arranged in the middle of the measuring platform 5, and an elastic supporting wheel 8 is arranged near the radial limiting mechanism. The wheel surface of the elastic supporting wheel 8 is arranged in contact with the measured part 1. The elastic supporting wheel 8 is used to reduce the up and down vibration of the measured part 1 during the rotation process. An adjusting foot cup 9 is arranged at the bottom end of the measuring platform 5 to ensure the level of the measuring platform 5.

[0041] The visual measurement mechanism includes a three-axis mobile platform 4.1, an image analysis system and a visual mechanism composed of an industrial camera 4.2, a matching lens 4.3 and a ring light source 4.4. The visual mechanism is installed on the three-axis mobile platform 4.1, and the three-axis mobile platform 4.1 is installed on the upper end of the measuring platform 5 and can drive the matching lens 4.3 in the visual mechanism to align with the threaded connection gap of the measured part 1 by adjusting the movement in the X-axis, Y-axis and Z-axis directions. The industrial camera 4.2 is connected to the three-axis mobile platform 4.1 through a camera frame, the matching lens 4.3 is connected to the industrial camera 4.2 and is positioned at the camera frame by a buckle, the ring light source 4.4 is located at the front end of the matching lens 4.3 and is connected to the camera frame through a light source frame, and the image analysis system is electrically connected to the industrial camera 4.2. The visual measurement mechanism uses Delta DMV2000 series multi-camera vision system as an image acquisition terminal.

[0042] The present invention also provides a method for visually measuring a threaded connection gap, comprising the following steps:

[0043] The part 1 to be measured, the radial limit mechanism, the circumferential rotation mechanism, and the visual measurement mechanism are all installed on the upper end of the measuring table 5; the position of the supporting lens 4.3 on the three-axis moving table 4.1 is adjusted so that it is directly opposite to the threaded connection gap of the part 1 to be measured, and the distance between the supporting lens 4.3 and the threaded connection gap is adjusted at the same time; the distance is obtained based on the calibration of the industrial camera 4.2 for the parts 1 to be measured with different diameters; the shaft end power source 3.5 is controlled to drive the part 1 to be measured to rotate at a uniform speed, and the industrial camera 4.2 takes a picture every time the part 1 to be measured rotates through a predetermined angle until the part 1 to be measured completes a full rotation; the image analysis system receives the image information transmitted by the industrial camera 4.2 and obtains the size data of the threaded connection gap.

[0044] In actual measurement, the rectangular range captured by the target surface of the industrial camera should be an arc surface (the arc within the rectangular frame). The curvature of the arc is related to the distance between the arc surface and the camera and the diameter of the part. The closer the distance and the larger the diameter, the flatter the rectangular range captured and the smaller the error. Therefore, targeted calibration is required for parts of different diameters. By establishing the correspondence between the known coordinates of the calibration object and the image points, the internal and external parameters of the camera model are obtained, the lens distortion is corrected, and the corrected image is generated to improve the accuracy of the measurement.

[0045] The calibration process involves the following steps: 1) Acquire calibration images: Use a camera to shoot a calibration plate (such as a chessboard) from different angles to ensure that the calibration plate is complete and clearly visible in each image; 2) Detect corner points: Use image algorithms to detect the corner points of the calibration plate in each image and obtain the coordinates of these corner points in the image coordinate system; 3) Calculate intrinsic parameters, extrinsic parameters and distortion parameters: Use the detected corner point coordinates and the known coordinates of the calibration plate corner points in the world coordinate system to calculate the camera's intrinsic parameters, extrinsic parameters and distortion parameters through the calibration function calibrateCamera in OpenCV; 4) Optimize and verify: Further optimize the calculated intrinsic and extrinsic parameters through optimization algorithms (such as the least squares method) to improve calibration accuracy. At the same time, use images that are not involved in the calibration to verify the calibration results to ensure the accuracy and reliability of the calibration parameters; 5) Apply the calibration results: After the calibration is completed, the obtained intrinsic parameters, extrinsic parameters and distortion parameters can be applied to subsequent image processing, 3D reconstruction and other tasks to improve processing effects and accuracy. In response to environmental interference problems such as changes in lighting during visual measurement, anti-interference measures or image processing are taken to ensure measurement accuracy, and physical methods are used to isolate interference when necessary.

[0046] A visual measurement device and method for threaded connection gaps designed by the present invention can solve the problems of low automation, poor accuracy, and low efficiency in threaded connection gap measurement, and the detection process is convenient and the detection results are accurate. The visual system provided by the present invention uses an industrial camera to collect high-quality gap images in a visual manner, detect the gaps in threaded connections, and improve detection accuracy. The visual measurement mechanism designed by the present invention is separated from the supporting structure of the measured part, which can ensure that the camera is not affected by the rotational vibration of the measured part during the measurement process. The visual measurement mechanism designed by the present invention is installed on a three-axis moving table, which is convenient for the subsequent adjustment of the camera position and can adapt to the measurement requirements of parts of different diameters, parts of different lengths, and changes in thread positions.

[0047] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A visual measuring device for threaded connection gap, characterized in that: It comprises a part to be measured (1), a radial limiting mechanism, a circumferential rotation mechanism, a visual measurement mechanism and a measuring platform (5); The periphery of the tested part (1) has a threaded connection gap; The radial limiting mechanism is sleeved on the circumference of the outer wall of the measured part (1) to prevent the measured part (1) from radially deviating during axial rotation; The rotating surface of the circumferential rotating mechanism is in close contact with the outer circumference of the measured part (1) for transmission, and is used to drive the measured part (1) to perform axial rotation, wherein the central axis of the measured part (1) is used as the rotation axis; The visual measuring mechanism points to the threaded connection gap position of the measured part (1) to obtain image information at the threaded connection gap, and the image analysis system of the visual measuring mechanism obtains the dimension data of the threaded connection gap based on the image information at the threaded connection gap; The radial limiting mechanism, the circumferential rotating mechanism and the visual measuring mechanism are all arranged at the upper end of the measuring platform (5).

2. A visual measuring device for threaded connection gap according to claim 1, characterized in that: The radial limiting mechanism comprises an annular member (2.1) and a bracket (2.2); the annular member (2.1) is annularly sleeved on the circumference of the outer wall of the measured part (1), and comprises an upper half ring and a lower half ring connected by bolts; the bracket (2.2) is connected between the annular member (2.1) and the measuring table (5); and the radial limiting mechanism avoids the threaded connection gap position of the measured part (1).

3. A visual measuring device for threaded connection gap according to claim 2, characterized in that: The circumferential rotation mechanism comprises a shaft end drive mechanism and two shaft end transmission mechanisms, the two shaft end transmission mechanisms are respectively located on both sides of the shaft end of the measured part (1), and the rotating surfaces of the two shaft end transmission mechanisms are in contact with the outer circumference of the measured part (1) for transmission; the shaft end drive mechanism is connected to one of the shaft end transmission mechanisms via a pulley drive.

4. A visual measuring device for threaded connection gap according to claim 3, characterized in that: The shaft end transmission mechanism comprises a first synchronous pulley (3.1), a first cylindrical roller (3.2), a first roller shaft (3.3) and a first bearing seat (3.4); the first roller shaft (3.3) is rotatably connected to the first bearing seat (3.4) via a bearing; the first synchronous pulley (3.1) and the first cylindrical roller (3.2) are both key-connected to the first roller shaft (3.3); The shaft end driving mechanism comprises a shaft end power source (3.5), a second synchronous belt pulley (3.6) and a belt (3.7); the output end of the shaft end power source (3.5) arranged at the upper end of the measuring platform (5) is connected to the second synchronous belt pulley (3.6); the second synchronous belt pulley (3.6) is connected to one of the first synchronous belt pulleys (3.1) through the belt (3.7).

5. The visual measuring device for threaded connection gap according to claim 3, characterized in that: An end baffle plate (6.1) is provided on the measuring table (5) at one end of the measured part (1) away from the circumferential rotation mechanism, and an end baffle wheel (6.2) is provided on the end surface of the measured part (1) close to the measured part (1). The end baffle wheel (6.2) is used to limit the axial transverse movement of the measured part (1).

6. A threaded connection gap visual measurement device according to claim 5, characterized in that: A guide rail (7.1) and a shaft-side auxiliary limiting mechanism are provided on the measuring platform (5); the guide rail (7.1) is provided at a position on the upper end of the measuring platform (5) close to the inner side of the shaft-end baffle (6.1) and arranged along the axial direction of the measured part (1); the shaft-side auxiliary limiting mechanism is slidably connected to the guide rail (7.1) and can achieve fixation of the positions of the two by a locking member; the shaft-side auxiliary limiting mechanism is used to perform radial auxiliary limiting on a side of the measured part (1) away from the shaft-end transmission mechanism.

7. A threaded connection gap visual measurement device according to claim 6, characterized in that: The shaft-side auxiliary limiting mechanism comprises two single-side limiting mechanisms and a connecting bottom plate (7.2); the single-side limiting mechanism comprises a second cylindrical roller (7.3), a second roller shaft (7.4) and a second bearing seat (7.5); the second roller shaft (7.4) is rotatably connected to the second bearing seat (7.5) via a bearing; the second cylindrical roller (7.3) is connected to the second roller shaft (7.4); the second cylindrical roller (7.3) is in contact with the outer circumference of the measured part (1) for transmission; The two single-side limit mechanisms are connected via a connecting base plate (7.2) and are respectively located on both sides of the measured part (1). The bottom of the connecting base plate (7.2) has a pulley that is slidably matched with the slide rail (7.1) and a hole that is bolted to the slide rail (7.1).

8. The threaded connection gap visual measurement device according to claim 3, characterized in that: A radial limiting mechanism is arranged in the middle of the measuring platform (5), an elastic support wheel (8) is arranged near the radial limiting mechanism, the wheel surface of the elastic support wheel (8) is arranged to fit the measured part (1), and the elastic support wheel (8) is used to reduce the up and down vibration of the measured part (1) during the rotation process. An adjusting foot cup (9) is arranged at the bottom end of the measuring platform (5).

9. The threaded connection gap visual measurement device according to claim 1, characterized in that: The visual measurement mechanism comprises a three-axis moving platform (4.1), an image analysis system and a visual mechanism consisting of an industrial camera (4.2), a matching lens (4.3) and an annular light source (4.4); the visual mechanism is mounted on the three-axis moving platform (4.1); the three-axis moving platform (4.1) is mounted on the upper end of a measuring platform (5) and can drive the matching lens (4.3) in the visual mechanism to align with the threaded connection gap of a measured part (1) by adjusting the movement in the directions of the X-axis, the Y-axis and the Z-axis; the industrial camera (4.2) is connected to the three-axis moving platform (4.1) through a camera frame; the matching lens (4.3) is connected to the industrial camera (4.2) and is positioned at the camera frame by a buckle; the annular light source (4.4) is located at the front end of the matching lens (4.3) and is connected to the camera frame through a light source frame; and the image analysis system is electrically connected to the industrial camera (4.2).

10. A method for visually measuring a threaded connection gap, based on the visual measuring device for threaded connection gap according to any one of claims 1 to 9, characterized in that: The following steps are involved: The measured part (1), the radial limiting mechanism, the circumferential rotation mechanism, and the visual measurement mechanism are all mounted on the upper end of the measuring table (5); The position of the matching lens (4.3) on the three-axis moving platform (4.1) is adjusted so that it faces the threaded connection gap of the measured part (1), and the distance between the matching lens (4.3) and the threaded connection gap is adjusted at the same time; the distance is obtained based on the calibration of the industrial camera (4.2) for the measured parts (1) of different diameters; The power source (3.5) at the end of the control shaft drives the measured part (1) to rotate at a constant speed, and the industrial camera (4.2) takes a picture each time the measured part (1) rotates through a predetermined angle until the measured part (1) completes a full rotation; The image analysis system receives the image information transmitted by the industrial camera (4.2), processes the image through wavelet analysis and least square sub-pixel algorithm, analyzes the image, and obtains the size data of the threaded connection gap.

Images