A heat exchange tube post-expansion milling device and a milling method

Abstract

A milling device and method for expanding heat exchanger tubes, relating to the field of milling technology. This invention includes a robot and a control system. The robot's end effector is connected to a milling head and a vision recognition mechanism. The milling head is used to mill, flatten, and deburr the expanded ends of the heat exchanger tubes. The vision recognition mechanism is used to scan, measure, and collect spatial position and extension length information of the tube ends. Through the integrated design of the robot, milling head, vision recognition mechanism, and control system, manual hand-held milling operations are replaced, fundamentally solving the problems of poor dimensional consistency, easy scratching of the inner wall of the heat exchanger tubes and the tube sheet material, and low processing efficiency caused by manual processing. Furthermore, relying on visual measurement and intelligent control, adaptive processing is achieved, matching the high-precision, fully digital processing requirements of tube sheets, realizing automated and precise milling of expanded heat exchanger tubes.

Description

Technical Field

[0001] This invention relates to the field of milling technology, specifically to a milling device and method for expanding heat exchanger tubes. Background Technology

[0002] In the manufacturing and assembly of steam turbines, expansion joint is a key connection process between heat exchange tubes and tube sheets. First, the heat exchange tubes are inserted into the tube sheet holes. The tube expansion device causes plastic deformation at the tube ends and elastic deformation of the tube sheet hole wall. The interference fit is used to achieve a tight connection and seal between the tube bundle and the tube sheet, which meets the structural strength requirements of steam turbines under high temperature, high pressure and high speed fluid conditions.

[0003] After the expansion joint is completed, the heat exchange tube ends will protrude from the tube sheet by a certain margin. Common problems include uneven protrusion length, tilted end face, tube end deformation, burrs and flash, which cannot meet the requirements of subsequent welding, assembly and airflow of the steam turbine. In order to ensure welding quality, eliminate stress concentration and avoid airflow turbulence and cavitation damage, the ends of the expanded heat exchange tubes must be milled to remove excess material, flatten the end face and remove burrs, so that the tube end dimensions and end face accuracy meet the steam turbine assembly standards.

[0004] Currently, manual hand-held milling cutters are mainly used for machining, resulting in poor dimensional consistency, easy scratching of the inner wall of heat exchange tubes and tube sheet substrate, and low machining efficiency. The publicly available robotic automated milling equipment can only achieve fixed program machining and cannot adaptively adjust the cutting depth according to the actual extension of a single tube after expansion, thus failing to meet the high-precision fully digital machining requirements of tube sheets. Summary of the Invention

[0005] The purpose of this invention is to address the problem that existing robotic automated milling equipment can only perform fixed-program processing and cannot meet the high-precision, fully digital processing requirements of tube sheets. Therefore, this invention provides a milling device and method for milling heat exchanger tubes after expansion.

[0006] The technical solution of the present invention is: a heat exchange tube expansion milling device, comprising: a robot, wherein the end of the robot is connected to a milling head and a vision recognition mechanism, and the milling head is used to mill, flatten, and deburr the tube end of the heat exchange tube after expansion.

[0007] The visual recognition mechanism is used to scan, measure, and collect information on the spatial position and extension length of the heat exchange tube ends.

[0008] The control system is electrically connected to the robot, the milling head, and the vision recognition mechanism, respectively. The control system is used to automatically plan the robot's motion trajectory based on measurement information and control the milling head to complete the milling operation.

[0009] Furthermore, the visual recognition mechanism is a cross laser visual recognition and positioning device, which can project a cross laser spot and acquire images of the pipe opening to obtain the coordinates of the pipe hole center, the spatial pose of the pipe end, and the extension length of the pipe end.

[0010] Furthermore, the milling head includes a servo motor, a planetary reducer, and a cutter head connected in sequence, with flat-bladed cutting blades connected to the cutter head.

[0011] Furthermore, the cutter head is provided with a chip-breaking structure located on the chip-exit side of the flat-edged insert. The chip-breaking structure can automatically break chips during milling to prevent iron chips from entangled in the insert and the cutter head.

[0012] Furthermore, the chip-breaking structure is a chip-breaking baffle or chip-breaking boss that is fixedly installed on the cutter head and cooperates with the flat-edged cutting blade.

[0013] Furthermore, the control system includes an expansion joint master station system and a milling tube slave station system that are electrically connected. The expansion joint master station system has a built-in expansion joint control program for controlling the expansion joint function of the heat exchange tube, and the milling tube slave station system has a built-in milling control program for controlling the milling function of the heat exchange tube.

[0014] A milling method for a heat exchanger tube expansion milling device as described in any of the above embodiments, comprising the following steps:

[0015] Step 1: A cross laser is projected onto the heat exchange tube opening using a cross laser vision recognition and positioning device. Laser point cloud data is collected based on the principle of triangulation. The data is then processed by software to obtain the three-dimensional coordinates of the tube hole center, the spatial pose of the tube end, and the tube end extension length.

[0016] Step 2: The control system acquires and automatically reads the pre-imported CAD drawings of the heat exchange tubes, and automatically generates the positions of all tube holes on the human-machine interface. The control system is then autonomously programmed to plan the integrated motion path of the robot's expansion and milling.

[0017] Step 3: The control system adaptively adjusts the robot's posture based on the difference in tube sheet flatness, completes the automatic centering and alignment of the milling head and the tube opening, and adjusts the cutter head surface and the tube opening to a parallel state;

[0018] Step 4: The control system automatically calculates the cutting parameters based on the actual extension length of the tube end, the diameter of the heat exchange tube, the wall thickness and material parameters, and converts them into the robot milling trajectory;

[0019] Step 5: The robot drives the milling head, which rotates the cutter head via a servo motor and planetary reducer. It uses flat-bladed inserts to complete the milling, flattening, and deburring of the pipe ends, while simultaneously using a chip-breaking structure to prevent iron chips from entangled.

[0020] Furthermore, it also includes the following steps:

[0021] Step Six: After milling is completed, the cross laser vision recognition and positioning device scans and measures the tube end dimensions and machining accuracy again to form a closed-loop verification and ensure that the machining quality meets the standards.

[0022] Furthermore, the robot's movement path includes at least one of the following path forms: straight line, cross, star pattern, serpentine, vertical jump, and horizontal jump.

[0023] Furthermore, the cutting parameters include the cutting amount, the number of cutting layers, and the feed rate per pass.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The heat exchanger tube expansion milling device provided by the present invention integrates a robot, a milling head, a vision recognition mechanism and a control system to replace manual hand-held milling cutter operation, fundamentally solving the problems of poor dimensional consistency, easy scratching of the inner wall of the heat exchanger tube and the tube sheet base material, and low processing efficiency in manual processing. Furthermore, it achieves adaptive processing by relying on vision measurement and intelligent control, which can match the high-precision fully digital processing requirements of the tube sheet and realize automated and precise operation of heat exchanger tube expansion milling. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0027] In the diagram: 1. Robot; 2. Milling head; 3. Vision recognition mechanism; 4. Control system. Detailed Implementation

[0028] Specific implementation method one: Combining Figure 1 This embodiment describes a robot 1 and a control system 4. The end effector of the robot 1 is connected to a milling head 2 and a vision recognition mechanism 3. The milling head 2 is used to mill, flatten, and deburr the ends of the heat exchange tubes after expansion. The vision recognition mechanism 3 is used to scan, measure, and collect spatial position information and extension length information of the heat exchange tube ends. The control system 4 is electrically connected to the robot 1, the milling head 2, and the vision recognition mechanism 3. The control system 4 is used to automatically plan the motion trajectory of the robot 1 based on the measurement information and control the milling head 2 to complete the milling operation.

[0029] The heat exchanger tube expansion milling device of this embodiment integrates robot 1, milling head 2, vision recognition mechanism 3 and control system 4 to replace manual hand-held milling cutter operation, fundamentally solving the problems of poor dimensional consistency, easy scratching of the inner wall of heat exchanger tube and tube sheet base material, and low processing efficiency of manual processing. Moreover, relying on vision measurement and intelligent control to achieve adaptive processing, it can match the high-precision fully digital processing requirements of tube sheet, and realize automated and precise operation of heat exchanger tube expansion milling.

[0030] Specific Implementation Method Two: Combining Figure 1 This embodiment differs from Specific Embodiment 1 in that the visual recognition mechanism 3 is a cross-laser visual recognition and positioning device. This device projects a cross-laser spot and acquires images of the tube opening to obtain the tube hole center coordinates, tube end spatial pose, and tube end extension length data. The principle is as follows: by irradiating the workpiece tube opening with a cross-laser and extracting the cross-laser point cloud data, the sensor acquires the laser image, which is then processed by software to obtain the cross-laser point cloud data within the laser scanning area. The software calculates the actual tube hole and surrounding spatial coordinates (X, Y, Z). Using this cross-laser visual recognition and positioning device, the actual extension length, tube hole center coordinates, and tube end pose of each heat exchange tube after expansion can be accurately acquired, providing precise data support for adaptive adjustment of the cutting depth. This solves the defect of the traditional robot 1, which cannot autonomously adjust processing parameters based on the actual extension amount of a single tube, ensuring uniform processing dimensions and meeting the high-precision processing requirements of the tube sheet. Other components and connections are the same as in Specific Embodiment 1.

[0031] Specific implementation method three: Combining Figure 1 This embodiment differs from Specific Embodiment 1 in that the milling head 2 includes a servo motor, a planetary reducer, and a cutter head connected in sequence. The cutter head is equipped with flat-edged cutting blades. This combined structure provides stable power output and controllable speed and feed, avoiding problems such as pipe deformation and inner wall scratches caused by uneven manual operation and insufficient rigidity of traditional equipment. It stably achieves integrated milling, flat-edging, and deburring, improving dimensional consistency and surface quality. Other components and connections are the same as in Specific Embodiment 1.

[0032] Specific implementation method four: Combination Figure 1This embodiment differs from Specific Embodiment Three in that it incorporates a chip-breaking structure on the cutter head. Located on the chip-exit side of the flat-bladed insert, this structure automatically breaks chips during milling, preventing them from entangled in the insert and cutter head. This avoids chips from wrapping around the flat-bladed insert and workpiece during milling, solving the problem of chips scratching the inner wall of the heat exchanger tubes and the tube sheet material in manual and traditional automated processing. It ensures a clean machining surface, guarantees continuous and smooth processing, and improves overall processing efficiency. Other components and connections are the same as in Specific Embodiment Three.

[0033] Specific Implementation Method Five: Combining Figure 1 This embodiment differs from Specific Embodiment Four in that the chip-breaking structure is fixedly mounted on the cutter head and consists of chip-breaking baffles or protrusions that cooperate with the flat-edged inserts. This design is simple, reliable, and provides stable chip-breaking performance. It prevents metal chips from scratching the workpiece without increasing equipment complexity, and can be stably adapted to batch processing of tube sheets for extended periods, continuously ensuring processing consistency and workpiece surface integrity. Other components and connections are the same as in Specific Embodiment Four.

[0034] Specific Implementation Method Six: Combination Figure 1 This embodiment differs from Specific Embodiment 1 in that the control system 4 includes an expansion joint master station system and a milling tube slave station system electrically connected. The expansion joint master station system has a built-in expansion joint control program for controlling the heat exchange tube expansion function, while the milling tube slave station system has a built-in milling control program for controlling the heat exchange tube milling function. By employing a control system 4 that coordinates the expansion joint master station and the milling tube slave station, seamless integration of the expansion joint and milling processes can be achieved, avoiding dimensional deviations caused by manual transfer and repeated positioning. It also supports digital linkage control, allowing real-time adjustment of milling parameters based on the expansion joint results, achieving fully digital intelligent machining and solving the problem that traditional equipment with fixed programs cannot adapt to actual on-site working conditions. Other components and connections are the same as in Specific Embodiment 1.

[0035] Specific implementation method seven: Combining Figure 1 This embodiment also provides a milling method for the above-described heat exchanger tube expansion milling device, comprising the following steps:

[0036] Step 1: A cross laser is projected onto the heat exchange tube opening using a cross laser vision recognition and positioning device. Laser point cloud data is collected based on the principle of triangulation. The data is then processed by software to obtain the three-dimensional coordinates of the tube hole center, the spatial pose of the tube end, and the tube end extension length.

[0037] Step 2: Control system 4 acquires and automatically reads the pre-imported heat exchanger tube CAD drawing, and automatically generates all tube hole positions on the human-machine interface. Control system 4 is autonomously programmed to plan the integrated motion path of robot 1 for tube expansion and milling.

[0038] Step 3: The control system 4 adaptively adjusts the posture of the robot 1 according to the difference in tube sheet flatness, completes the automatic centering and alignment of the milling head 2 with the tube opening, and adjusts the cutter head surface and the tube opening to a parallel state;

[0039] Step 4: The control system 4 automatically calculates the cutting parameters based on the actual extension length of the tube end, the diameter of the heat exchange tube, the wall thickness and material parameters, and converts them into the milling trajectory of the robot 1;

[0040] Step 5: Robot 1 drives the milling head 2, which in turn drives the cutter head to rotate via a servo motor and planetary reducer. The cutter head is then rotated using a flat-bladed insert to complete the milling, flattening, and deburring of the pipe end. Simultaneously, a chip-breaking structure is used to prevent the chips from tangling.

[0041] The milling method in this embodiment is based on visual measurement data, combined with CAD drawings to autonomously plan the path, adaptively center, and automatically calculate cutting parameters. It can dynamically adjust the cutting depth according to the actual extension of each heat exchanger tube, thus breaking free from the limitations of fixed-program machining. Other components and connections are the same as any one of the specific embodiments one to six.

[0042] Specific implementation method eight: Combination Figure 1 This embodiment differs from specific embodiment seven in that it also includes the following steps:

[0043] Step Six: After milling, the cross-shaped laser vision recognition and positioning device scans and measures the tube end dimensions and machining accuracy again, forming a closed-loop verification to ensure that the machining quality meets the standards. This second visual inspection after machining forms a closed-loop verification, real-time checking of the machining dimensions and accuracy of each tube end, timely correction of deviations, and ensuring that the machining quality of all heat exchange tubes meets the standards uniformly. This process eliminates the batch dimensional deviations and quality instability problems that are prone to occur with manual labor and fixed-program equipment. Other components and connections are the same as in Specific Implementation Method Seven.

[0044] Specific Implementation Method Nine: Combining Figure 1 This embodiment differs from specific embodiment seven in that the robot 1's motion path includes at least one of the following forms: straight line, cross, star pattern, serpentine, vertical jump, and horizontal jump. This provides multiple motion paths for the robot 1, adaptable to tube sheets with different layouts, avoiding processing interference, and ensuring efficient and stable operation of the robot 1. Other components and connections are the same as in specific embodiment seven.

[0045] Specific Implementation Method Ten: Combining Figure 1This embodiment differs from Specific Embodiment Seven in that the cutting parameters include the cutting amount, the number of cutting layers, and the single feed rate. The optimal parameters are automatically matched based on the actual extension of the single pipe, pipe diameter, wall thickness, and material, avoiding problems such as pipe end deformation, uneven end face, and inner wall damage caused by excessive or insufficient cutting. Other components and connections are the same as in Specific Embodiment Seven.

[0046] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

Claims

1. A heat exchange tube expanded and milled device, characterized by, include: Robot (1), the end of which is connected to a milling head (2) and a vision recognition mechanism (3), the milling head (2) is used to mill, flatten and deburr the tube ends after the heat exchange tubes are expanded; The visual recognition mechanism (3) is used to scan, measure, and collect information on the spatial position and extension length of the heat exchange tube end. The control system (4) is electrically connected to the robot (1), the milling head (2) and the vision recognition mechanism (3) respectively. The control system (4) is used to automatically plan the motion trajectory of the robot (1) according to the measurement information and control the milling head (2) to complete the milling operation.

2. The heat exchanger tube expansion and milling device according to claim 1, characterized in that, The visual recognition mechanism (3) is a cross laser visual recognition positioning device. The cross laser visual recognition positioning device can project a cross laser spot and collect images of the pipe opening to obtain the center coordinates of the pipe hole, the spatial pose of the pipe end, and the extension length of the pipe end.

3. The heat exchanger tube expansion and milling device according to claim 1, characterized in that, The milling head (2) includes a servo motor, a planetary reducer and a cutter head connected in sequence, and a flat-bladed blade is connected to the cutter head.

4. The heat exchanger tube expansion and milling device according to claim 3, characterized in that, The cutter head is provided with a chip breaking structure, which is located on the chip exit side of the flat-bladed insert. The chip breaking structure can automatically break chips during milling to prevent iron chips from entangled in the flat-bladed insert and the cutter head.

5. The heat exchanger tube expansion milling device according to claim 4, characterized in that, The chip-breaking structure is a chip-breaking baffle or chip-breaking boss that is fixedly installed on the cutter head and cooperates with the flat-bladed cutting tool.

6. The heat exchanger tube expansion milling device according to claim 1, characterized in that, The control system (4) includes an expansion joint master station system and a milling tube slave station system that are electrically connected. The expansion joint master station system has a built-in expansion joint control program for controlling the expansion joint function of the heat exchange tube, and the milling tube slave station system has a built-in milling control program for controlling the milling function of the heat exchange tube.

7. A milling method for the heat exchanger tube expansion milling device as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: A cross laser is projected onto the heat exchange tube opening using a cross laser vision recognition and positioning device. Laser point cloud data is collected based on the principle of triangulation. The data is then processed by software to obtain the three-dimensional coordinates of the tube hole center, the spatial pose of the tube end, and the tube end extension length. Step 2: The control system (4) acquires and automatically reads the pre-imported heat exchanger tube CAD drawing, and automatically generates all tube hole positions on the human-machine interface. The control system (4) autonomously programs and plans the robot (1) expansion and milling tube integrated motion path. Step 3: The control system (4) adaptively adjusts the posture of the robot (1) according to the difference in tube sheet flatness, completes the automatic centering and alignment of the milling head (2) with the tube opening, and adjusts the cutter head surface and the tube opening to a parallel state; Step 4: The control system (4) automatically calculates the cutting parameters based on the actual extension length of the tube end, the diameter of the heat exchange tube, the wall thickness and material parameters, and converts them into the robot's (1) milling trajectory; Step 5: The robot (1) drives the milling head (2), and drives the cutter head to rotate through the servo motor and planetary reducer. It uses flat-blade inserts to complete the milling, flat-blade and deburring of the pipe end, and simultaneously avoids the entanglement of iron chips through the chip breaking structure.

8. The milling method of the heat exchanger tube expansion milling device according to claim 7, characterized in that, It also includes the following steps: Step Six: After milling is completed, the cross laser vision recognition and positioning device scans and measures the tube end dimensions and machining accuracy again to form a closed-loop verification and ensure that the machining quality meets the standards.

9. The milling method of the heat exchanger tube expansion milling device according to claim 7, characterized in that, The robot (1) has a movement path that includes at least one of the following: a straight line, a cross, a star shape, a snake shape, a vertical jump, and a horizontal jump.

10. The milling method of the heat exchanger tube expansion milling device according to claim 7, characterized in that, The cutting parameters include the cutting amount, the number of cutting layers, and the feed rate per pass.

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