A production apparatus and processing method for thin-walled micro-pitch high-efficiency heat exchange tubes

Abstract

A production apparatus and processing method for thin-walled micro-pitch high-efficiency heat exchange tubes are disclosed, relating to the field of high-efficiency heat exchange tube production technology. The production apparatus of this invention includes a frame, a tie rod, a core head, a lead screw module, a servo motor, a claw plate, and a rolling head. One end of the tie rod is mounted on the frame and parallel to the bottom of the frame. The end of the tie rod away from the frame is connected to the core head. A servo motor is mounted on the end of the frame away from the tie rod. The output end of the servo motor is connected to the lead screw module. A claw plate is mounted on the lead screw module. The rolling head is mounted on the frame. The high-efficiency heat exchange tubes produced by the method of this invention are of great significance for energy saving, water saving, saving operating costs, and reducing reinvestment. They also have advantages such as low resistance, small size, and material saving.

Description

Technical Field

[0001] This invention relates to the field of high-efficiency heat exchanger tube manufacturing technology, and in particular to a thin-walled micro-pitch high-efficiency heat exchanger tube manufacturing apparatus and its processing method. Background Technology

[0002] The tubes of condensers and evaporators, made of the same material, manufactured using the same process, and with essentially the same function (heat exchange or heat dissipation), can be collectively referred to as heat exchange tubes. Existing high-efficiency heat exchange tubes mainly include evaporator tubes and condenser tubes, which are usually made of metal, such as copper. However, during long-term use, the surfaces exposed to air or in contact with the medium are prone to corrosion. Furthermore, because their teeth are relatively close together and the transition between the teeth is not smooth, scale easily forms on the surface, making cleaning difficult.

[0003] Titanium and titanium alloy welded tubes possess excellent strength, hardness, low density, light weight, high and low temperature resistance, good machinability, excellent corrosion resistance, are non-magnetic and non-toxic, exhibit good heat exchange performance, and also possess shape memory and superconducting properties. Therefore, titanium and titanium alloys are increasingly being used in the production of high-efficiency heat exchange tubes. However, due to limitations in processing methods in existing titanium tube production equipment, the wall thickness is generally above 0.5 mm, severely impacting heat exchange efficiency. Furthermore, if the inside of the tube is not properly cleaned during use, a fouling layer can easily form, significantly affecting heat exchange efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a production device and processing method for a novel high-efficiency micro-particle heat exchanger tube with thin wall and titanium alloy, thereby solving the problems of titanium tubes being limited by processing devices and methods, having excessively thick tube walls, and being inconvenient to clean the inner tube, which easily leads to the formation of a fouling layer.

[0005] The technical solution adopted by the present invention to solve its technical problem is as follows: a thin-walled micro-pitch high-efficiency heat exchange tube production device, including a frame, a tie rod, a core head, a lead screw module, a servo motor, a claw plate, and a rolling head. One end of the tie rod is located on the frame and parallel to the bottom of the frame. The end of the tie rod away from the frame is connected to the core head. A servo motor is located at the end of the frame away from the tie rod. The output end of the servo motor is connected to the lead screw module. A claw plate is located on the lead screw module. The rolling head is located on the frame.

[0006] Furthermore, the rolling head includes a feed motor, a main shaft, a turntable, and blades. The turntable is mounted on the frame and has a through hole at its center for the tube to pass through. Blades are mounted on the turntable and are connected to the feed motor via the main shaft. The feed motor controls the rotation of the blades, while the turntable precisely controls the blade feed position to ensure the rolling depth of the tube.

[0007] Furthermore, the blades are provided in four sets, and each of the four sets of blades is equipped with a matching spindle and a propulsion motor.

[0008] The processing method of the thin-walled micro-pitch high-efficiency heat exchange tube production device of the present invention is achieved through the following steps:

[0009] 1. Adjust the center position of the mandrel to be coplanar with the four sets of blades to ensure that the mandrel can support the pipe under stress during the rolling process of the four sets of blades;

[0010] 2. Insert the pipe horizontally into the tie rod so that the core head is inside the pipe to support it and position it. Then, bring the claw plate close to the pipe and fix the end of the pipe.

[0011] 3. Start the four propulsion motors to drive the four sets of blades to rotate;

[0012] 4. The rotary table drives four sets of blades to feed the tube evenly until it reaches the set position. When the four sets of blades contact the outer wall of the tube, the tube rotates with the rotation of the four sets of blades. After the four sets of blades are fed to the set position, the tube is rolled in one circle to form a single specific arc groove, and the processing difficulty of the tube is calculated.

[0013] 5. The rotary table drives the four sets of blades to retract away from the pipe and return to their original position;

[0014] 6. The servo motor starts, driving the lead screw module to rotate. The rotation of the lead screw module controls the claw plate to move forward and backward a set distance, thereby controlling the pipe to move forward and backward to the set distance.

[0015] 7. Repeat steps 4, 5, and 6 to complete the rolling process of the short arc groove of the pipe, so that the outer surface of the high-efficiency heat exchange tube forms an arc groove and a cylindrical straight pipe section.

[0016] Furthermore, in step 4, the difficulty of pipe processing needs to be calculated, specifically including:

[0017] 4-1, According to the friction law f = n·P (where n is the coefficient of friction and P is the normal force exerted on the pipe by the blade), in step 4, the pipe is subjected to the normal force exerted by four sets of blades, that is, the resultant torque generated by the four frictional forces f about the center of the pipe is 4fL2 (L2 is the lever arm of the normal force P and the frictional force f about the axis of the pipe), which is greater than the resistance torque 4PL1 generated by the normal force (L1 is the lever arm of the normal force P about the axis of the pipe), that is:

[0018] 4fL2=4n·PL2≥4PL1, transforming it gives n≥L1 / L2(1);

[0019] 4-2, Calculate based on geometric relationships:

[0020]

[0021] Substituting (2) and (3) into (1) yields:

[0022] Where R is the radius of the blade, r is the radius of the pipe, and θ is the blade center angle corresponding to the arc length of the contact between the pipe and the blade. However, the angle θ is actually very small, and should actually be cosθ / 2≈1. Therefore, (4) simplifies to:

[0023]

[0024] 4-3. Since each set of blades generates compression when it comes into contact with the pipe, let Z be the unit compression of a single blade. When the change in angle θ is small, it can be approximated as follows:

[0025] We can obtain:

[0026] Substituting (7) into (6), we get:

[0027] Substituting (8) into (5) yields:

[0028] Squaring both sides of (9) and simplifying, we get:

[0029] Where D is the diameter of the blade and d is the diameter of the pipe;

[0030] 4-4, Analyze according to the relationship in (10): When the relative unit compression When the value is small, then The value is smaller, and when it reaches a certain value... Negligible, thus simplifying (10) to obtain:

[0031]

[0032] Then, the processing difficulty of the pipe was calculated based on the relationship in (11).

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. The high-efficiency heat exchange tube produced using the device and method of this invention has an outer wall composed of arc-shaped grooves arranged at certain intervals and in a regular pattern, and cylindrical straight pipe sections, with each arc-shaped groove on the same cross section. The inner wall is composed of arc-shaped protrusions formed at corresponding positions of the outer wall grooves and cylindrical straight pipe sections. Within the cylindrical straight pipe sections, the fluid flows in a uniform diameter stream; within the arc-shaped pipe sections, the fluid flows in a variable diameter stream. The fluid generates a throttling effect at the inlet of the arc-shaped pipe section and a jetting effect at the outlet. The combined effect of these two effects generates numerous tiny vortices and transverse flows within the tube, which strongly interfere with and erode the fluid boundary layer and fouling layer. Simultaneously, the tiny vortices and transverse flows generated within the tube disrupt the formation of the fluid boundary layer and alter the state of the fouling layer, greatly enhancing heat exchange between the inside and outside of the tube. This results in high heat transfer efficiency, low energy consumption, and high safety and reliability.

[0035] 2. The high-efficiency heat exchange tube produced by the device and method of the present invention, due to the regular changes in the cross-section of the arc groove section and the cylindrical straight tube section, undergoes secondary disturbance under the pressure before and after the arc section, which greatly destroys the boundary layer thermal resistance; at the same time, the arc section can also accumulate energy, which increases the heat transfer coefficient.

[0036] 3. The high-efficiency heat exchange tube produced by the device and method of the present invention has a large-radius smooth transition at the connection position between the arc groove section and the cylindrical straight tube section, which avoids excessive residual stress and working stress generated by sharp angles, thereby improving the fatigue life of the heat exchange tube and reducing the probability of stress corrosion. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0038] Figure 2 for Figure 1 Cross-sectional view of the central turntable;

[0039] Figure 3 A schematic diagram illustrating the analysis of rolling high-efficiency heat exchange tubes for a thin-walled micro-pitch high-efficiency heat exchange tube production device;

[0040] Figure 4 This is a schematic diagram of the high-efficiency heat exchange tube produced by the present invention;

[0041] Figure 5 for Figure 4 A sectional view;

[0042] In the diagram: 1. Tie rod, 2. Tube, 3. Propulsion motor, 4. Roller head, 5. Core head, 6. Spindle, 7. Claw plate, 8. Screw module, 9. Servo motor, 10. Frame, 11. Turntable, 12. Cutter head one, 13. Cutter head two, 14. Cutter head three, 15. Cutter head four. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] See attached document Figure 1 and attached Figure 2 This embodiment includes a frame 10, a pull rod 1, a mandrel 5, a lead screw module 8, a servo motor 9, a claw plate 7, and a rolling head 4. One end of the pull rod 1 is located on one end of the frame 10 and is parallel to the bottom of the frame 10. The end of the pull rod 1 away from the frame 10 is connected to the mandrel 5. The end of the frame 10 away from the pull rod 1 is equipped with the servo motor 9, and the output end of the servo motor 9 is parallel to the bottom of the frame 10. The output end of the servo motor 9 is connected to the lead screw module 8. The claw plate 7 is located on the lead screw module 8 and is perpendicular to the lead screw module 8. The rolling head 4 is vertically mounted on the frame 10 and is located between the connection end of the pull rod 1 and the frame 10 and the servo motor 9. At the same time, when the tube 2 is placed on the device, the mandrel 5 is located inside the tube 2 and is used to support the inside of the tube during the rolling process, preventing the tube 2 from becoming flat or elliptical due to uneven stress during the rolling process. The claw plate 7 is used to fix the end of the tube 2 away from the pull rod 1.

[0045] The rolling head 4 includes a turntable 11, blades 12, 13, 14, and 15 evenly arranged on the turntable 11, and four feed motors 3 corresponding to the four sets of blades via four main shafts 6. The turntable 11 has a through hole at its center for the tube to pass through. By connecting the blades 12, 13, 14, and 15 to the four feed motors 3 via the four main shafts 6, the feed motors 3 drive the four sets of blades to rotate. Since the blades 12, 13, 14, and 15 are all arranged on the turntable 11, when the tube 2 passes through the through hole in the center of the turntable 11 and is fixed on the device, the turntable 11 can drive the four sets of blades to feed evenly toward the tube 2 or retract away from the tube 2 and return to the initial position, thereby ensuring the rolling depth of the tube 2. The servo motor 9 drives the lead screw module 8 to rotate, and the rotation of the lead screw module 8 drives the control claw disk 7 to move back and forth. During the rolling process of the tube 2, the first blade 12, the second blade 13, the third blade 14, and the fourth blade 15 roll the tube 2 to form a specific arc groove segment. In order to ensure the different spacing of the arc groove segment, the claw disk 7 can move the tube 2 forward or backward to a set distance.

[0046] See attached document Figure 4 and attached Figure 5The high-efficiency heat exchange tube produced in this embodiment consists of an outer wall composed of regularly spaced, arc-shaped grooves and cylindrical straight sections, with each arc-shaped groove on the same cross-section. The inner wall is composed of arc-shaped protrusions corresponding to the outer wall grooves and cylindrical straight sections. Within the cylindrical straight sections, the fluid flows in a constant-diameter stream, while within the arc-shaped sections, it flows in a variable-diameter stream. A throttling effect is generated at the inlet of the arc-shaped section, and a jetting effect is generated at the outlet. The combined effect of these two effects creates numerous tiny vortices and transverse flows within the tube, strongly interfering with and eroding the fluid boundary layer and fouling layer. Simultaneously, the tiny vortices and transverse flows generated within the tube disrupt the formation of the fluid boundary layer and alter the state of the fouling layer, significantly enhancing heat exchange between the inside and outside of the tube. This results in high heat transfer efficiency, low energy consumption, and high reliability. Furthermore, due to the regular changes in the cross-sections of the arc-shaped groove section and the cylindrical straight pipe section, secondary disturbances occur under the pressure before and after the arc section, greatly reducing the boundary layer thermal resistance. Simultaneously, the arc section can accumulate energy, increasing the heat transfer coefficient. The presence of the groove section in the high-efficiency heat exchange tube produced in this embodiment reduces the axial stiffness of the heat exchange tube, significantly alleviating the thermal stress caused by temperature differences between the tube side and shell side. When the fluid flows from the cylindrical straight pipe section into the arc section, the pressure decreases and the flow velocity increases as the flow channel cross-section contracts. As the fluid flows past the crest, the flow channel cross-section gradually expands, increasing the pressure and decreasing the velocity. The appropriate ratio of the diameters of the groove section and the cylindrical straight pipe section alters the flow field distribution in the pipe, enhancing the heat transfer effect of the pipe wall.

[0047] This embodiment also provides a processing method using the above-described production apparatus, which is achieved through the following steps:

[0048] 1. Adjust the center position of the mandrel to be coplanar with the four sets of blades to ensure that the mandrel can support the pipe under stress during the rolling process of the four sets of blades;

[0049] 2. Insert the pipe horizontally into the tie rod so that the core head is inside the pipe to support it and position it. Then, bring the claw plate close to the pipe and fix the end of the pipe.

[0050] 3. Start the four propulsion motors to drive the four sets of blades to rotate;

[0051] 4. The rotary table drives four sets of blades to feed the tube evenly until it reaches the set position. When the four sets of blades contact the outer wall of the tube, the tube rotates with the rotation of the four sets of blades. After the four sets of blades are fed to the set position, the tube is rolled in one circle to form a single specific arc groove, and the processing difficulty of the tube is calculated.

[0052] 5. The rotary table drives the four sets of blades to retract away from the pipe and return to their original position;

[0053] 6. The servo motor starts, driving the lead screw module to rotate. The rotation of the lead screw module controls the claw plate to move forward and backward a set distance, thereby controlling the pipe to move forward and backward to the set distance.

[0054] 7. Repeat steps 4, 5, and 6 to complete the rolling process of the short arc groove of the pipe, so that the outer surface of the high-efficiency heat exchange tube forms an arc groove and a cylindrical straight pipe section.

[0055] See attached document Figure 3 In step 4, the pipe processing method is calculated:

[0056] 4-1, According to the friction law f = n·P (where n is the coefficient of friction and P is the normal force exerted on the pipe by the blade), in step 4, the pipe is subjected to the normal force exerted by four sets of blades, that is, the resultant torque generated by the four frictional forces f about the center of the pipe is 4fL2 (L2 is the lever arm of the normal force P and the frictional force f about the axis of the pipe), which is greater than the resistance torque 4PL1 generated by the normal force (L1 is the lever arm of the normal force P about the axis of the pipe), that is:

[0057] 4fL2=4n·PL2≥4PL1, transforming it, we get n≥L1 / L2 (1)

[0058] 4-2, Calculate based on geometric relationships:

[0059]

[0060] Substituting (2) and (3) into (1) yields:

[0061] Where R is the radius of the blade, r is the radius of the pipe, and θ is the blade center angle corresponding to the arc length of the contact between the pipe and the blade. However, the angle θ is actually very small, and should actually be cosθ / 2≈1. Therefore, (4) simplifies to:

[0062]

[0063] 4-3. Since each set of blades generates compression when it comes into contact with the pipe, let Z be the unit compression of a single blade. When the change in angle θ is small, it can be approximated as follows:

[0064] We can obtain:

[0065] Substituting (7) into (6), we get:

[0066] Substituting (8) into (5) yields:

[0067] Squaring both sides of (9) and simplifying, we get:

[0068] Where D is the diameter of the blade and d is the diameter of the pipe;

[0069] 4-4, Analyze according to the relationship in (10): When the relative unit compression When the value is small, then The value is smaller, and when it reaches a certain value... Negligible, thus simplifying (10) to obtain:

[0070]

[0071] Then, the processing difficulty of the pipe was calculated based on the relationship in (11).

[0072] In conclusion:

[0073] 1) The friction coefficient *n* follows a quadratic relationship under rotating conditions. Therefore, increasing the friction coefficient *n* is beneficial for improving rotating conditions. However, an increased friction coefficient will increase tool wear, resulting in a rougher tool surface. The surface roughness formed by the tool pressing the tube will also increase, reducing the surface quality of the finished product. During cold rolling, to obtain a higher tube surface quality, the cutting edge of the blade is usually machined to be relatively smooth, and an appropriate coolant is used, which also serves as a lubricant. A low friction coefficient becomes the main factor limiting the amount of rolling deformation, thus limiting its relative compression value.

[0074] 2) Based on the limit value of relative compression in 1), the larger the ratio of the diameter D of the blade to the diameter d of the tube, the easier it is to rotate the tube and the less difficult it is to process.

[0075] 3) When the ratio of unit compression Z to pipe diameter d increases, it will be more difficult for the rolled part to rotate, the rotation conditions will worsen, and the processing difficulty will increase.

Claims

1. A processing method for a thin-walled micro-pitch high-efficiency heat exchange tube production device, the production device comprising a frame, a tie rod, a mandrel, a lead screw module, a servo motor, a claw disk, and a rolling head, wherein one end of the tie rod is mounted on the frame and parallel to the bottom of the frame, the end of the tie rod away from the frame is connected to the mandrel, a servo motor is mounted on the end of the frame away from the tie rod, the output end of the servo motor is connected to the lead screw module, a claw disk is mounted on the lead screw module, the rolling head is mounted on the frame, the rolling head comprises a feed motor, a main shaft, a turntable, and blades, the turntable is mounted on the frame, a through hole is provided at the center of the turntable for the tube to pass through, blades are mounted on the turntable, the blades are connected to the feed motor via the main shaft, thereby controlling the rotation of the blades by the feed motor, and the turntable achieves precise control of the blade feed position to ensure the rolling depth of the tube, the blades are arranged in four sets, each of the four sets of blades is equipped with a matching main shaft and feed motor, characterized in that, the steps include: (1) Adjust the center position of the mandrel to be coplanar with the four sets of blades to ensure that the mandrel can support the pipe under stress during the rolling process of the four sets of blades; (2) Insert the pipe horizontally into the tie rod so that the core head is inside the pipe to support the pipe and position the pipe. Then, bring the claw plate close to the pipe and fix the end of the pipe. (3) Start the four propulsion motors to drive the four sets of blades to rotate; (4) The turntable drives four sets of blades to feed the pipe evenly until it reaches the set position. When the four sets of blades contact the outer wall of the pipe, the pipe rotates with the four sets of blades. After the four sets of blades are fed to the set position, the pipe is rolled once to form a single specific arc groove, and the processing difficulty of the pipe is calculated. Methods for calculating the difficulty of pipe processing include: 4-1, According to the friction law f=n·P (where n is the coefficient of friction and P is the normal force exerted on the pipe by the blade), in step 4, the pipe is subjected to the normal force exerted by the four sets of blades, that is, the resultant torque generated by the four frictional forces f about the center of the pipe is 4fL2 (L2 is the lever arm of the normal force P and the frictional force f about the axis of the pipe), which is greater than the resistance torque 4PL1 generated by the normal force (L1 is the lever arm of the normal force P about the axis of the pipe), that is: 4fL2=4n·PL2≥4PL1, transforming it gives n≥L1 / L2 (1; 4-2, Calculate based on geometric relationships: (2); （3）； Substituting (2) and (3) into (1), we get: (4); Where R is the radius of the blade, r is the radius of the pipe, and θ is the blade center angle corresponding to the contact arc length between the pipe and the blade. (4) can be simplified to: （5）； 4-3. Since each set of blades generates compression when it comes into contact with the pipe, let Z be the unit compression of a single blade. When the change in angle θ is small, it can be approximated as follows: (6); We can obtain: (7); Substituting (7) into (6), we get: (8); Substituting (8) into (5) yields: (9); Squaring both sides of (9) and simplifying, we get: (10); Where D is the diameter of the blade and d is the diameter of the pipe; 4-4, Analyze according to the relationship in (10): When the relative unit compression When the value is small, then The value is smaller, and when it reaches a certain value... Negligible, thus simplifying (10) to obtain: （11）； Then, the processing difficulty of the pipes was calculated based on the relationship in (11); (5) The rotary table drives the four sets of blades to retract away from the pipe and return to their original positions; (6) The servo motor starts and drives the lead screw module to rotate. The rotation of the lead screw module controls the claw disk to move forward and backward a set distance, thereby controlling the pipe to move forward and backward to the set distance. (7) Repeat steps 4, 5, and 6 to complete the rolling process of the short arc groove of the pipe so that the outer surface of the high-efficiency heat exchange tube forms an arc groove and a cylindrical straight pipe section.

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