System and method for automatically detecting expanding amount of tube on heat exchanger tube plate

Abstract

The invention discloses a system for automatically detecting the expanding amount of a tube on a heat exchanger tube plate. The system comprises a base, a robot, a robot control cabinet and an industrial personal computer, a tail end shaft of the robot is fixedly connected with a bias plate, and the bias plate is fixedly provided with a global camera, a local camera and a laser range finder; a shell is connected to the offset plate, an anti-rotation sleeve and a cover plate are sequentially and fixedly arranged at the front end of the shell, a linear motor is fixedly arranged on the rear side of the shell, an electric push rod of the linear motor is fixedly connected with a convex cone, a concave cone is arranged on the front side of the convex cone and comprises an anti-rotation sliding block and a connecting shaft, a groove is formed in the rear side of the anti-rotation sliding block, and the anti-rotation sliding block is arranged in an anti-rotation hole of the anti-rotation sleeve in a sliding mode. The connecting shaft penetrates through the cover plate in a sliding mode, an inner diameter gauge offset block is fixedly connected to the connecting shaft, and an inner diameter gauge is arranged on the inner diameter gauge offset block. The invention further discloses a method for automatically detecting the expanding amount of the tube on the heat exchanger tube plate. According to the invention, systematization, automation and intellectualization of detection are realized, manpower is saved, wrong detection and missing detection caused by human factors can be avoided, the accuracy of measurement data is ensured, and the detection precision and the detection efficiency are improved.

Description

Technical Field

[0001] The invention relates to a system and method for detecting the diameter expansion of a tube, in particular to a system and method for automatically detecting the diameter expansion of a tube on a tube plate of a heat exchanger. Background Art

[0002] During the manufacturing process of heat exchangers, the connection quality between the heat exchange tube and the tube sheet is an important indicator of product quality. The connection between the tube and the tube sheet should be tight and have good sealing performance to ensure the heat transfer efficiency of the heat exchanger.

[0003] The tube and the tube sheet are mostly connected by "strength welding + expansion", which constitutes the boundary of the medium on both sides of the heat exchanger and is the weakest point in the entire heat exchanger. The welding (sealing welding) between the tube and the tube sheet is demanding and difficult. The gap between the tube and the tube sheet is eliminated by expansion and diameter expansion, thereby protecting the sealing weld. During the operation of the equipment, due to structural and stress reasons, this connection part is most likely to be damaged and fail. Therefore, during the manufacturing process, the quality of the weld and expansion joints needs to be strictly inspected to avoid weld failure due to inadequate expansion joints.

[0004] After the sealing welding, the weld is subjected to 100% PT inspection and 100% helium leak detection to ensure that there are no defects exceeding the standard in the weld, and then the expansion of the tube-tube sheet and 100% diameter expansion are inspected to ensure that all expansions meet the process requirements. At present, the diameter expansion inspection requires manual inspection through the inner diameter gauge hole by hole. Due to the large number of tubes and their dense distribution, the inspection process is huge. The inspection personnel cannot work continuously. The human eye is prone to fatigue during the inspection process, and it is easy to make mistakes and miss inspections. If the inspection results are to be recorded hole by hole, at least two people are required to cooperate to complete it, and the amount of recorded data is huge, which is time-consuming and labor-intensive, and it is easy to make recording errors. At the same time, it is not easy to record the inspection results hole by hole, and the data is not intuitive and difficult to save, which affects the accuracy and efficiency of the inspection. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a system and method for automatically detecting the diameter expansion of tubes on a heat exchanger tube sheet, which can realize systematization, automation and intelligence of detection, save manpower, avoid errors and omissions caused by human factors, ensure the accuracy of measurement data, and improve detection accuracy and efficiency.

[0006] In order to achieve the above-mentioned purpose, the present invention provides an automatic detection system for the expansion amount of tubes on a heat exchanger tube sheet, comprising a base, a robot, a robot control cabinet, and an industrial computer; characterized in that: an offset plate is fixedly connected to the end shaft of the robot, and a global camera, a local camera and a laser rangefinder are fixedly arranged on the offset plate; a shell is connected to the offset plate, an anti-rotation sleeve and a cover plate are fixedly arranged at the front end of the shell in sequence, a linear motor is fixedly arranged in the shell, an electric push rod of the linear motor is fixedly connected to a convex cone, a concave cone is arranged at the front side of the convex cone, the concave cone includes a fixed anti-rotation slider and a connecting shaft, a groove matched with the convex cone is arranged at the rear side of the anti-rotation slider, the anti-rotation slider is slidably placed in the anti-rotation hole of the anti-rotation sleeve, the cross-section of the anti-rotation slider and the anti-rotation hole is a matching polygon, the connecting shaft slides through the cover plate, an inner diameter gauge offset block is fixedly connected to the connecting shaft, and an inner diameter gauge is arranged on the inner diameter gauge offset block; the linear motor, the global camera, the local camera and the laser rangefinder are all connected to the industrial computer.

[0007] The present invention uses an automatic detection method for the expansion amount of tubes on a heat exchanger tube sheet using the above system, comprising the following steps: 1) System initialization: placing the workpiece to be tested and the detection system in place, adjusting the height of the workpiece to be tested, and ensuring that all the tube holes of the tubes are covered; after the system is turned on, a system self-check is performed, system parameters are set, the robot is reset, the robot joints are reset, and the operating status of each device is checked to ensure the normal operation of each device; 2) Acquiring pictures and image processing: by moving the end axis of the robot, the global camera captures the overall image of the tube sheet, and according to the initial image, the three coplanar points of the tube sheet are automatically searched, and then the workpiece posture calibration is completed by the laser rangefinder. After being processed by the contour extraction algorithm, the image coordinates of the center of the tube hole are obtained and the tube holes to be tested are numbered; 3) Tube mouth positioning: according to each center image coordinate, the robot space coordinates corresponding to each tube hole are obtained; then, the end axis of the mobile robot and the local camera are used to capture high-precision local images of each tube hole, and according to the graphic processing The algorithm identifies and extracts the center of the circle and the contour of the circle, and determines the center coordinates of all the holes to be tested; 4) Motion path planning: According to the coordinates of the center of all the holes, they are numbered, combined with the calibration results of the robot end position, the navigation algorithm plans the motion path of the detection device, and verifies the number of holes according to the hole design drawing to verify whether the detection path is correct; 5) Diameter expansion detection: According to the motion path, the robot moves the detection probe of the internal diameter gauge to the axis where the center of the corresponding hole is located; the linear motor starts, its electric push rod extends, the convex cone is inserted into the groove of the concave cone, and the concave cone is pressed tightly against the cover plate; the robot manipulates the detection probe of the internal diameter gauge to move along the axis where the center of the corresponding hole is located, and passes through the non-expanded area, expanded area and non-expanded area of ​​the pipe in turn to measure the inner diameter value. During measurement, the linear motor controls its electric push rod to retract, the convex cone and the concave cone are separated, and the concave cone and the internal diameter gauge are in a floating state; the measurement data of each hole is recorded according to the number, and it is judged whether the expansion size meets the requirements; The present invention is centered on an industrial computer and can issue instructions to a linear motor, a global camera, a local camera and a laser rangefinder to realize data acquisition, image processing, detection data analysis and storage, and visualization chart display; a coordinate relationship between the system and the workpiece is established by a robot hand-eye calibration method to realize rapid and automatic alignment of the tube plate; the system is equipped with two industrial cameras: a global camera captures the overall image of the tube plate, a global large-viewing-field camera preliminarily locates the workpiece, and then a local camera captures a high-precision local tube hole image to accurately determine the center coordinates of the tube hole, plan the optimal detection path, and solve the contradiction between large-viewing-field planning and small-area accuracy, thereby achieving a dual improvement in positioning efficiency and accuracy; during measurement, a flexible connection is adopted between the inner diameter gauge and the shell, and the detection probe is in a relatively relaxed state, thereby realizing motion accuracy compensation, avoiding collision between the detection probe and the tube plate, and being in a free and non-stressed state when reading data, thereby ensuring accurate measurement data; the present invention can realize systematization, automation and intelligence of detection, save manpower, avoid false and missed detections caused by human factors, and improve detection accuracy and efficiency; As a further improvement of the present invention, a thrust sensor is provided on the offset plate on the axial rear side of the housing, the thrust sensor is connected to the industrial computer, a stopper is fixedly provided on the housing on the rear side of the anti-rotation sleeve, and the convex cone passes through the stopper; during measurement, if there is an abnormal object in the pipe, the radial instrument is blocked from moving forward, and the resistance is transmitted to the thrust sensor through the stopper, etc., which can prompt the operator to handle it, thereby preventing the radial instrument from being damaged; As a further improvement of the present invention, two guide rods are fixedly arranged in the housing, and the convex cone is fixedly connected with a slide seat sleeved on the two guide rods; the movement of the convex cone can be guided and rotation can be prevented; As a further improvement of the present invention, the bias plate is connected to the housing through a quick-change disk; other detection devices, such as a helium detection probe, can be replaced through the quick-change disk to expand the detection range; As a further improvement of the automatic detection method of the expansion amount of the present invention, it also includes: 6) result display, storage and processing: the detection results are transmitted to the industrial computer, and various forms of data in the detection process can be observed in real time, and the results can be analyzed and saved for subsequent processing; the detection data can be presented in the form of two-dimensional charts, three-dimensional bar charts, and data lists on the display screen of the industrial computer, so that the real-time detection status can be intuitively viewed, unqualified pipe holes can be quickly located, and data results can be analyzed, which is helpful to analyze and improve the production process and improve the overall performance of the product; In summary, the present invention can realize systematization, automation and intelligence of detection, save manpower, avoid false or missed detection caused by human factors, ensure the accuracy of measurement data, and improve detection accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a stereogram of an embodiment of the present invention.

[0009] Figure 2 for Figure 1 A magnified view of the mid-end detection tool.

[0010] Figure 3 for Figure 2 Top view of the .

[0011] Figure 4 for Figure 2 Partial view of the middle shell and cover.

[0012] Figure 5 for Figure 4 View without the cover and concave pyramid.

[0013] Figure 6 for Figure 4 View without the cover.

[0014] Figure 7 for Figure 6 Stereoscopic image of a concave pyramid.

[0015] Figure 8 for Figure 6 Stereoscopic image of a convex pyramid.

[0016] Fig. 9 for Figure 6 Reverse stereoscopic view of the linear motor's electric push rod moving forward.

[0017] Fig.10 for Figure 6 Reverse stereogram of the linear motor's push rod as it moves backward. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings.

[0019] like Figures 1 to 9As shown, an automatic detection system for the diameter expansion of tubes on a heat exchanger tube sheet of this embodiment includes a base 1, a robot 2, a robot control cabinet 3, and an industrial computer 4; a biasing plate 5 is fixedly connected to the end shaft of the robot 2, and a terminal detection tool 6 is provided on the biasing plate 5; the terminal detection tool 6 includes a global camera 7, a local camera 8, a laser rangefinder 9, and an inner diameter gauge 10 fixedly arranged on the biasing plate 5; the biasing plate 5 is connected to a shell 12 through a quick-change disk 11 and a flange 15, and an anti-rotation sleeve 13 and a cover plate 14 are fixedly arranged at the front end of the shell 12 in sequence, a linear motor 16 is fixedly arranged in the shell 12, the linear motor 16 is fixedly connected to the flange 15 or the shell 12, and an electric push rod 17 of the linear motor 16 is fixedly connected to a convex pyramid 18 with a quadrangular front end, a concave pyramid is provided on the front side of the convex pyramid 18, and the concave pyramid includes a fixed anti-rotation slider 19 and a connecting shaft 20, and the rear side of the anti-rotation slider 19 is provided with a convex pyramid matching A prismatic groove 31, an anti-rotation slider 19 is slidably placed in the anti-rotation hole 29 of the anti-rotation sleeve 13, and the cross-sections of the anti-rotation slider 19 and the anti-rotation hole 29 are matched quadrilaterals, which can prevent the connecting shaft 20 from rotating; two guide rods 21 fixedly connected to the flange 15 are fixedly arranged in the shell 12, and the convex pyramid 18 is fixedly connected to a slide seat 22 sleeved on the two guide rods 21; a thrust sensor 23 is provided on the offset plate 5 on the axial rear side of the shell 12, and a stopper 24 is fixedly arranged on the shell 12 on the rear side of the anti-rotation sleeve 13, and the convex pyramid 18 passes through the stopper 24; the connecting shaft 20 slides through the cover plate 14, and an internal diameter gauge offset block 26 is fixedly connected to the connecting shaft 20, and the internal diameter gauge 10 is arranged on the internal diameter gauge offset block 21; the robot control cabinet 3, the linear motor 16, the global camera 7, the local camera 8, the thrust sensor 23 and the laser rangefinder 9, and the digital amplifier 28 of the internal diameter gauge 10 are all connected to the industrial computer 4.

[0020] The present invention uses the above-mentioned system to automatically detect the expansion amount of tubes on the tube sheet of a heat exchanger, and includes the following steps: 1) System initialization: Place the workpiece to be tested (welded tube sheet and tube) and the detection system in place, adjust the height of the workpiece to be tested, and ensure that all the tube holes of the tubes can be covered; after the system is turned on, perform system self-check, set system parameters, reset the robot, reset each joint of the robot, and check the operating status of each device to ensure the normal operation of each device; 2) Get pictures and image processing: Move the end axis of the robot 2 through the industrial computer 4 and the robot control cabinet 3, so that the global camera 7 takes the overall image of the tube sheet, and automatically search for three coplanar points of the tube sheet according to the initial image, and then complete the workpiece posture calibration through the laser rangefinder 9. After processing by the contour extraction algorithm, obtain the image coordinates of the center of each tube hole and the industrial computer 4 to number the tube holes to be tested; 3) Tube mouth positioning: The industrial computer 4 obtains the spatial coordinates of each tube hole corresponding to the robot according to each center image coordinate; Then, the high-precision local images of each tube hole are taken by moving the end axis of the robot and the local camera 8, and the industrial computer 4 performs according to the graphics processing algorithm. The center of the circle and the contour of the circle are identified and extracted, and the center coordinates of all the holes to be tested are determined; 4) Motion path planning: The industrial computer 4 obtains the coordinates of the center of all the holes and numbers them, and combines the calibration results of the robot end position to plan the motion path of the detection device by the navigation algorithm, and verifies the number of holes according to the hole design drawing to verify whether the detection path is correct; 5) Diameter expansion detection: According to the motion path, by controlling the robot 2, the detection probe 27 of the internal diameter gauge 10 is moved to the axis where the center of the corresponding hole is located; start the linear motor 16 and its electric push rod 17 is extended, the convex pyramid 1 is inserted into the prismatic groove 31 of the concave pyramid, and the concave pyramid is pressed tightly against the cover plate 14. At this time, the concave pyramid cannot move relative to the convex pyramid 18, so that the inner diameter gauge 10 can be accurately sent into the pipe along the axis where the center of the pipe hole is located; then the robot 2 controls the detection probe 27 of the inner diameter gauge 10 to move along the axis where the center of the pipe hole is located, and successively passes through the non-expanded area, the expanded area and the non-expanded area of ​​the pipe to measure the inner diameter value. During the measurement, the linear motor 16 controls its electric push rod 17 to retract, and the convex pyramid 18 is separated from the concave pyramid (such as Fig.10 As shown), the concave pyramid and the inner diameter gauge 10 are in a floating state; the measurement data of each pipe hole is recorded according to the number, and whether the expansion size meets the requirements is determined; 6) Result display, storage and processing: the test results are transmitted to the industrial computer, and various forms of data in the test process can be observed in real time, the visual result analysis can be saved and subsequently processed; The present invention is centered on the industrial computer 4, which can issue instructions to the robot 2, the linear motor 16, the global camera 7, the local camera 8 and the laser rangefinder 9 to realize data acquisition, image processing, detection data analysis and storage, and visual chart display, thereby improving the automation and intelligence of the system; the robot 2 cooperates with the global camera 7 and adopts the hand-eye calibration method to establish the coordinate relationship between the system and the workpiece, so as to realize the rapid and automatic alignment of the tube sheet; the global camera 7 and the local camera 8 configured in the system are both industrial cameras: the global camera 7 takes the overall image of the tube sheet, the global large-viewing-field camera preliminarily locates the workpiece, and then the local camera 8 with higher precision takes the high-precision local tube hole. Image, accurately determine the center coordinates of the pipe hole, plan the optimal detection path, solve the contradiction between large field of view planning and small area accuracy, and achieve double improvement of positioning efficiency and accuracy; during measurement, the internal diameter gauge 10 and the shell 12 are flexibly connected and floating, the detection probe 27 is in a relatively relaxed state, and can automatically correct the position on the radial section of the pipe and its own pitch angle to achieve motion accuracy compensation. When reading data, it is in a free and non-stressed state to ensure accurate measurement data; in summary, the present invention can realize systematization, automation, and intelligence of detection, save manpower, avoid false omissions caused by human factors, and improve detection accuracy and efficiency; During measurement, if there is an abnormal object in the tube or the detection probe 27 collides with the tube sheet, the radial instrument 10 is blocked from moving forward, the anti-rotation slider 19 retreats and contacts the stopper 24, and the resistance is transmitted to the thrust sensor 23 through the stopper 24 and the rear connecting piece, which can prompt the operator to handle it, ensure the smooth progress of the detection and prevent the radial instrument 10 from being damaged; the two guide rods 21 and the slide seat 22 can guide the movement of the convex pyramid 18 and prevent it from rotating; other detection devices, such as helium detection probes, can be replaced through the quick-change plate 11 to expand the detection range; The present invention is illustrated through the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only used for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. For example, the cross-sections of the anti-rotation slider and the anti-rotation hole may be matching triangles or hexagons.

Claims

1. An automatic detection system for the expansion of tubes on a heat exchanger tube sheet, comprising a base, a robot, a robot control cabinet, and an industrial computer; characterized in that: A bias plate is fixedly connected to the terminal shaft of the robot, and a global camera, a local camera and a laser rangefinder are fixedly arranged on the bias plate; a shell is connected to the bias plate, an anti-rotation sleeve and a cover plate are fixedly arranged on the front end of the shell in sequence, a linear motor is fixedly arranged on the rear side of the shell, a convex cone is fixedly connected to the electric push rod of the linear motor, a concave cone is arranged on the front side of the convex cone, the concave cone includes a fixed anti-rotation slider and a connecting shaft, a groove matched with the convex cone is arranged on the rear side of the anti-rotation slider, the anti-rotation slider is slidably placed in the anti-rotation hole of the anti-rotation sleeve, the cross-section of the anti-rotation slider and the anti-rotation hole are matched polygons, the connecting shaft slides through the cover plate, an internal diameter gauge bias block is fixedly connected to the connecting shaft, and an internal diameter gauge is arranged on the internal diameter gauge bias block; the linear motor, the global camera, the local camera and the laser rangefinder are all connected to the industrial computer.

2. The automatic detection system for the expansion amount of tubes on a heat exchanger tube sheet according to claim 1, characterized in that: A thrust sensor is arranged on the biasing plate at the axial rear side of the housing, and the thrust sensor is connected to the industrial control computer; a stopper is fixedly arranged on the housing at the rear side of the anti-rotation sleeve, and the convex cone passes through the stopper.

3. The automatic detection system for the expansion amount of tubes on a heat exchanger tube sheet according to claim 1 or 2, characterized in that: Two guide rods are fixedly arranged in the shell, and the convex cone is fixedly connected with a sliding seat sleeved on the two guide rods.

4. The automatic detection system for the expansion amount of tubes on a heat exchanger tube sheet according to claim 3, characterized in that: The bias plate is connected to the housing through a quick-change plate.

5. A method for automatically detecting the expansion of tubes on a heat exchanger tube sheet, characterized in that The following steps are involved: 1) System initialization: Place the workpiece to be tested and the detection system in place, adjust the height of the workpiece to be tested, and ensure that all the tube holes are covered; after the system is turned on, perform a system self-check, set system parameters, reset the robot, reset the robot joints, and check the operating status of each device to ensure the normal operation of each device; 2) Get pictures and image processing: Move the robot's end axis to allow the global camera to capture the overall image of the tube sheet. According to the initial image, automatically search for three coplanar points on the tube sheet, and then use the laser rangefinder to complete the workpiece posture calibration. After processing with the contour extraction algorithm, obtain the image coordinates of the center of the tube hole. Mark and number the pipe holes to be tested; 3) Pipe mouth positioning: According to the coordinates of each center image, the robot space coordinates corresponding to each pipe hole are obtained; then the robot end axis and local camera are used to shoot high-precision local images of each pipe hole, and the center and circle contour are identified and extracted according to the graphics processing algorithm, and the center coordinates of all pipe holes to be tested are determined; 4) Motion path planning: According to the numbering of the center coordinates of all pipe holes, combined with the calibration results of the robot end position, the navigation algorithm plans the motion path of the detection device, and verifies the number of pipe holes according to the pipe hole design drawing to verify whether the detection path is correct; 5) Diameter expansion detection: According to the motion path, the robot moves the detection probe of the internal diameter gauge to the axis where the center of the corresponding pipe hole is located; the linear motor starts, its electric push rod extends, the convex cone is inserted into the groove of the concave cone, and the concave cone is pressed tightly against the cover plate; the robot manipulates the detection probe of the internal diameter gauge to move along the axis where the center of the corresponding pipe hole is located, and successively passes through the non-expansion area, expansion area and non-expansion area of ​​the pipe to measure the inner diameter value. During measurement, the linear motor controls its electric push rod to retract, the convex cone is separated from the concave cone, and the concave cone and the internal diameter gauge are in a floating state; the measurement data of each pipe hole is recorded according to the number, and it is judged whether the expansion size meets the requirements.

6. A method for automatically detecting the expansion amount of tubes on a heat exchanger tube sheet as claimed in claim 5, characterized in that Also includes: 6) Result display, storage and processing: The test results are transmitted to the industrial computer through the data interface, and various forms of data in the test process can be observed in real time, and the results can be analyzed and saved for subsequent processing.

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