Process for preparing reinforced heat transfer tube with porous metal coating based on sintering method

Abstract

The invention discloses a process for preparing a reinforced heat transfer pipe with a porous metal coating based on a sintering method, and relates to the technical field of heat transfer pipe preparation, the reinforced heat transfer pipe comprises a shell with two through ends, and further comprises rotating gas rings, the rotating gas rings are installed in the two ends of the shell, and the gas path input ends of the rotating gas rings are communicated with the output end of an external high-pressure argon source; the inner circumferential side of the rotating gas ring and the outer circumferential side of the machined part coaxially rotate and are in sliding fit, and the shell communicates with a through-out pipe. The heating layer is mounted on the inner side of the shell; and a telescopic guide rail frame. After external high-pressure argon is input through the rotating gas ring, a driving assembly in the supporting driving mechanism drives a supporting rod to move around a guide rail frame in the circumferential direction, and a pneumatic assembly on the supporting rod works to drive a plurality of guide wheels to rotate, so that the guide wheels make contact with a machined part to drive the machined part to rotate slowly and move axially; and sintering operation is conducted on the machined part in the moving process of the machined part, and the sintering effect of machining is improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat transfer tube preparation, and in particular to a process for preparing a reinforced heat transfer tube by preparing a porous metal coating based on a sintering method. Background Art

[0002] The heat transfer tube is a passive heat transfer element with extremely high thermal conductivity. Through the phase change heat transfer principle and capillary suction, it can achieve rapid heat transfer without additional power. The existing sintered heat exchange tube is a high-efficiency heat exchange tube with a specific structure of metal porous layer formed by sintering on the surface of the bare tube.

[0003] In the process of preparing the heat transfer tube, the metal powder of the coating is rapidly heated at high temperature under the action of the medium frequency induction current. The small amount of flux doped in it is melted at high temperature and distributed in the gaps of the metal particles without flowing out and falling off. At the same time, due to the presence of the pore-forming agent, the decomposed hydrogen will escape outward to form pores or remove part of the ash in the gaps. In traditional technology, metal powder is usually coated on the surface of the heat transfer tube. Since the slurry has a certain fluidity, it is difficult to ensure the uniformity of the coating thickness using the above method.

[0004] In the existing preparation of heat transfer tubes, the workpiece is directly pushed into the sintering furnace without rotating it, and is pushed out from the other end after waiting for a sufficient time. The workpiece coating porosity sintered by this method is not high, and the processing effect is uneven, which leads to the final heat dissipation effect of the product is not uniform; it is easy to press on the upper part to affect the better hole formation of the workpiece, and the coating of the workpiece is damaged due to the clamping operation. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art of directly pushing the workpiece into the sintering furnace without rotating it, and pushing it out from the other end after waiting for a sufficient time, so that the porosity of the coating of the sintered workpiece is not high and the processing effect is uneven, and a process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method is proposed.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A process for preparing a reinforced heat transfer tube with a porous metal coating based on a sintering method, comprising the following steps: S1: Surface pretreatment of the base pipe: solvent cleaning combined with mechanical polishing and hot air blowing are used to remove residual oil, oxide scale and paint on the surface of the pipe or the processed part; S2: Roughening of the base tube surface: On a special tube shot blasting machine or shot peening machine, the tubes are processed in batches by using shot peening or shot peening technology to make the surface of the tube reach a certain roughness; S3: Apply adhesive: Apply a layer of adhesive evenly on the surface of the roughened metal pipe by spraying or roller brushing for 2 times, and let it dry naturally or air dry for 2 hours; the adhesive is liquid silica sol; S4: Mixing and granulating metal powder raw materials: mainly metal powder, binder, lubricant, and other additives; they need to be mixed, stirred, and evenly dispersed in a cylindrical rotary mixer, and cooled to form mixed particles after discharge. The metal powder is first heated to 110-130°C, and then these raw materials are weighed and added to the mixer, stirred for 10-15 minutes, so that the metal powder is coated with a layer of organic film; S5: Injection molding: Use a twin-screw injection molding machine to heat and extrude the mixed particles into a special mold. At this time, the pipe passes through the mold at a uniform speed, and the melted and extruded mixture continuously and evenly covers the surface of the pipe to form a uniform outer skin. During injection molding, the metal coating reserves a thickness margin; S6: Debonding: remove part of the polymer binder in the injection mixture to maintain the metal powder structure. The debonding method uses low-temperature heating, i.e. 150°C-180°C, and slowly heats. During the debonding process, the pipe should be kept at 30-50 rpm. Part of the binder is not removed and seeps out and adheres to the outer surface of the metal particles. S7: Sintering: Ensure that the metal powder forms an open porous connection shape, so that the metal powder forms solid sintering; under the action of medium frequency induction current, the coated metal powder is quickly heated to 1060℃-1080℃, wherein the doped flux is melted at high temperature and distributed in the gaps of the metal particles. At the same time, due to the presence of the pore-forming agent, the decomposed hydrogen will escape outward to form pores or remove part of the ash in the gaps; S8: Cooling: After surface sintering, the pipes continuously enter the cooling tunnel for water cooling. The cooling section, heating section and insulation section are connected tunnels, all of which are protected by argon gas. When the temperature drops below 400°C, the pipes are cooled by water spray when they leave the cooling tunnel. After cooling, the pipes are straightened by straightening equipment. S9: Subsequent treatment: Surface inspection of the pipe, removal of the socket and trimming of the pipe end, as well as ultrasonic cleaning, pickling and passivation of the pipe; The above-mentioned process for preparing the enhanced heat transfer tube with porous metal coating by sintering method also involves a preparation device, including a shell with two ends connected, and also includes: Rotating gas rings, both ends of the shell are equipped with rotating gas rings, the gas path input end of the rotating gas ring is connected with the output end of the external high-pressure argon gas source, the inner circumference of the rotating gas ring rotates coaxially with the outer circumference of the workpiece and slides together, and the shell is connected with an outlet pipe; A heating layer, wherein the heating layer is installed inside the housing; A retractable guide rail frame, wherein two guide rail frames are symmetrically distributed at both ends of the housing, the top of the guide rail frame is a telescopic section, and the bottom is an elastic section, the input end of the telescopic section is connected to the output end of the rotating air ring, a fixing rod is fixedly connected between the bottom end of the elastic section and the bottom of the housing, and the bottom of the workpiece slides coaxially with the inner circumference of the elastic section and rotates in coordination; A support driving mechanism, wherein the plurality of support driving mechanisms include a support rod, both ends of the support rod are connected with a driving assembly, the working end of the driving assembly is connected to a guide rail frame at the same end, and is used to drive the support rod to move circumferentially around the guide rail frame, a pneumatic assembly is connected inside the support rod, the input end of the pneumatic assembly is connected to the output end of the rotating air ring, and the output end is connected to a plurality of guide wheels, the guide wheels located in the elastic section are all against the outer side of the bottom of the workpiece, a sapphire sensor is installed on the guide rail frame, the sensing end of the sapphire sensor is pressed against the outer side of the workpiece located in the elastic section, and is electrically connected to a controller, the controller is installed on the outer casing, and receives the signal of the sapphire sensor to control the working state of the external high-pressure argon gas source.

[0007] In the above-mentioned process for preparing a heat transfer tube enhanced with a porous metal coating by sintering, the outer sides of both ends of the shell are fixedly connected with fixing sleeves.

[0008] In the above-mentioned process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method, the input end of the rotating air ring gas circuit is a total air inlet, and the total air inlet is connected with an inlet pipe. The inlet pipe is connected with an output end of an external high-pressure argon gas source at one end away from the rotating air ring, and a channel for the inlet pipe to pass through is opened on the fixed sleeve. The output end of the rotating air ring gas circuit includes two groups, one group is a double air outlet, and the other group is connected with a plurality of pressure-stabilizing valves. The plurality of pressure-stabilizing valves correspond one-to-one to the plurality of pneumatic component input ends at the same end. An air pipe is connected between the double air outlet and the telescopic section input end and between the pressure-stabilizing valve and the pneumatic component input end, and the air pipe is made of a hose.

[0009] In the above-mentioned process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method, the guide rail frame includes a rigid outer guide rail, a rigid inner guide rail, an elastic inner guide rail and an elastic outer guide rail, the rigid outer guide rail and the rigid inner guide rail are both retractable structures, the bottom end of the rigid outer guide rail is fixedly connected to the top end of the elastic outer guide rail, and form an outer frame with a rectangular frame on the top and a semicircular frame on the bottom, the bottom end of the rigid inner guide rail is fixedly connected to the top end of the elastic inner guide rail, and form an inner frame with a rectangular frame on the top and a semicircular frame on the bottom, the inner frame is concentrically arranged in the outer frame, the bottom of the outer frame is fixedly connected to a fixed rod, a plurality of the drive assemblies are slidably mounted on the inner frame and the outer frame, the inner peripheral side of the elastic inner guide rail slides coaxially and rotates with the outer peripheral side of the workpiece, and the sapphire sensor is installed between the rigid inner guide rail and the elastic inner guide rail.

[0010] In the above-mentioned process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method, the rigid outer guide rail and the rigid inner guide rail each include two branch rails, the tops of the two branch rails are coaxially slidably sleeved with the same movable guide rail, and the bottom ends are fixedly connected to the corresponding elastic inner guide rail and elastic outer guide rail, the tops of the two branch rails are fixedly connected with ear plates, the opposite sides of the two ear plates are fixedly connected with pistons, the outer peripheral sides of the two pistons are sealed and slidably connected with the same telescopic cylinder, a vent is opened in the middle of the telescopic cylinder, and the vent is connected to the double air outlet through an air pipe at one end away from the telescopic cylinder.

[0011] In the above-mentioned process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method, the driving assembly includes a limit plate, which is fixedly connected to the end of a support rod, and two motors are installed on the limit plate. The output ends of the two motors are coaxially fixedly connected to rollers, and tracks are provided on the inner frame and the outer frame. The two rollers rotate one by one and rest against the adjacent sides of the two tracks at the same end. The two motors are electrically connected to a controller, and the controller is used to control the working state of the two motors to make the support rod move circumferentially around the gap between the inner frame and the outer frame.

[0012] In the above-mentioned process for preparing an enhanced heat transfer tube with a porous metal coating based on a sintering method, the pneumatic component includes an air channel, and the two air channels are coaxially penetrated and opened on the support rod, and are distributed along the vertical line direction of the inner frame and the outer frame. One end of the two air channels is a branch air inlet, and the other end is a branch air outlet, and the branch air inlet and the branch air outlet on the two air channels are arranged in opposite positions. The branch air inlet is connected to the output end of the pressure regulating valve through an air pipe, and the branch air outlet is connected to the inside of the outer shell. A plurality of wheel axles are rotatably connected in the support rod, and fan blades are coaxially fixedly connected to the wheel axle. A rotating chamber for rotating the fan blades is opened in the support rod, and the rotating chamber is connected and cooperated with the two air channels. The end of the fan blade extends into the two air channels, and the wheel axle seals and penetrates the support rod close to one end of the workpiece, and is coaxially fixedly connected to the guide wheel.

[0013] In the above-mentioned process for preparing a heat transfer tube enhanced with a porous metal coating based on a sintering method, a plurality of axles on a same support rod are sleeved with a same synchronous belt.

[0014] In the above-mentioned process for preparing enhanced heat transfer tubes with porous metal coatings based on sintering method, the wheel axle extends out of the support rod and one end of the guide wheel is coaxially fixedly connected with a disc, and the disc is rotatably connected to the side close to the guide wheel with two pressing rollers, and the two pressing rollers are pressed against the outer wall of the synchronous belt.

[0015] In the above-mentioned process for preparing enhanced heat transfer tubes with porous metal coatings based on sintering method, the support rod is a hollow structure with both ends penetrated, and a partition plate is fixedly connected inside the support rod, and the two sides of the partition plate and the inner circumference of the support rod form two through air passages.

[0016] Compared with the prior art, the advantages of the present invention are: The present invention sets a support driving mechanism. After external high-pressure argon gas is input through a rotating gas ring, a driving component in the support driving mechanism drives the support rod to move circumferentially around the guide rail frame. The pneumatic component on the support rod drives multiple guide wheels to rotate, thereby driving the workpiece to rotate slowly and move axially through the contact between the guide wheels and the workpiece. The workpiece is sintered during its movement to improve the sintering effect. The workpiece is transported and supported in an ultra-high temperature environment through pneumatic mechanical transmission to avoid failure of magnetic and electrical equipment in the ultra-high temperature environment.

[0017] The present invention arranges a guide rail frame. Since the upper portion of the guide rail frame is a rectangular frame and the lower portion is a semicircular frame, the support driving mechanism moving on the semicircular frame can drive the processing, and the support driving mechanism moving to the rectangular frame does not contact the workpiece, so the decomposed hydrogen can be better overflowed to form an open porous structure in the coating, thereby improving the porosity, avoiding the pressure and obstruction of the guide wheel that will cause the hydrogen to be unable to overflow and increase the probability of structural formation failure, thereby realizing the rotation and semi-enclosed support of the workpiece, reducing pressure to improve the porosity.

[0018] The present invention provides a retractable guide rail frame. When the temperature change during the sintering process causes the workpiece to shrink, the sapphire sensor sends a corresponding signal. The controller receives the signal and controls the external high-pressure argon gas source to reduce the pressure of the argon gas introduced, so that the pressure in the telescopic cylinder of the telescopic section of the guide rail frame becomes smaller. Under the elastic action of the elastic inner guide rail and the elastic outer guide rail, the rigid outer guide rail and the rigid inner guide rail shrink toward the center along the movable guide rail, so that the sapphire sensor is re-attached to the workpiece, thereby ensuring that the end face of the guide wheel is always in contact with the workpiece, preventing the workpiece from shaking or failing to rotate in the workpiece due to non-fitting, and always maintaining the supporting and driving effect on the workpiece, so that when the workpiece shrinks and expands, it can be better covered and supported, and excessive force will not be applied to cause damage to the coating and reduce the porosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall structure of a process for preparing a heat transfer tube enhanced by preparing a porous metal coating based on a sintering method proposed by the present invention; Figure 2 A cross-sectional view of the outer shell and the fixed sleeve of a process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to the present invention; Figure 3This is a schematic structural diagram of the rotating gas ring, guide rail frame and support rod part of a process for preparing a heat transfer tube enhanced by sintering a porous metal coating; Figure 4 for Figure 3 The enlarged view of point A in the middle; Figure 5 for Figure 3 The enlarged view of point B in the middle; Figure 6 This is a schematic structural diagram of the rotating gas ring and the pressure-stabilizing valve part of a process for preparing an enhanced heat transfer tube using a sintering method to prepare a porous metal coating, as proposed by the present invention; Figure 7 A schematic diagram of the structure of a guide rail frame for a process for preparing a heat transfer tube enhanced by preparing a porous metal coating by sintering method proposed by the present invention; Figure 8 A half-section diagram of the telescopic tube portion of a process for preparing a heat transfer enhancement tube using a sintering method to prepare a porous metal coating according to the present invention; Fig. 9 This is a schematic structural diagram of the support rod and guide wheel parts of a process for preparing a heat transfer tube enhanced by preparing a porous metal coating based on a sintering method proposed by the present invention; Fig.10 A half-section diagram of the support rod and the partition plate portion of a process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to the present invention; In the figure: 1. outer shell; 11. fixed sleeve; 12. inlet pipe; 13. outlet pipe; 14. heating layer; 2. rotating air ring; 20. main air inlet; 201. double air outlet; 21. pressure regulating valve; 22. air pipe; 3. rigid outer guide rail; 31. rigid inner guide rail; 32. elastic inner guide rail; 33. elastic outer guide rail; 331. fixing rod; 34. sapphire sensor; 35. limit plate; 351. motor; 352. roller; 36. ear plate; 361. piston; 362. telescopic cylinder; 363. vent; 37. movable guide rail; 4. support rod; 41. sub-inlet; 42. sub-outlet; 43. guide wheel; 431. axle; 432. pressing roller; 433. fan blade; 44. synchronous belt; 45. partition plate; 5. processed parts. DETAILED DESCRIPTION

[0020] The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0021] Reference Figure 1-Figure 10 A process for preparing a heat transfer tube with a porous metal coating by sintering method comprises the following steps: S1: Surface pretreatment of the base tube: solvent cleaning combined with mechanical polishing and hot air blowing are used to remove residual oil, oxide scale and paint on the surface of the tube, i.e., the workpiece 5; S2: Roughening of the base pipe surface: Use shot peening or shot blasting technology on a special pipe shot blasting machine or shot peening machine to batch process the pipes so that the surface of the pipes reaches a certain roughness, which is conducive to the bonding of the adhesive and the coating; S3: Applying adhesive: Apply a layer of adhesive evenly on the surface of the roughened metal pipe by spraying or roller brushing for 2 times, and let it dry naturally or in the air for 2 hours; the adhesive is liquid silica sol, and the base silica sol helps to improve the bonding strength between the porous metal coating and the base metal during the high-temperature sintering process; S4: Mixing and granulating metal powder raw materials: mainly metal powder, binder, lubricant, and other additives; need to be mixed, stirred, and evenly dispersed in a cylindrical rotary mixer, and cooled to form mixed particles after discharge. The metal powder is first heated to 110-130°C, and heated to 120°C in actual operation, and then these raw materials are weighed and added to the mixer, stirred for 10-15 minutes, and stirred for 12 minutes in actual operation, so that most of the metal powder is covered with a layer of organic film, which is conducive to subsequent molding; S5: Injection molding: Use a twin-screw injection molding machine to heat and extrude the mixed particles into a special mold. At this time, the pipe passes through the mold at a uniform speed. The melted and extruded mixture continuously and evenly covers the surface of the pipe, similar to forming a uniform outer skin. During injection molding, the metal coating reserves a thickness margin. S6: Debonding: remove part of the polymer binder in the injection mixture to maintain the metal powder structure. The debonding method uses low-temperature heating method, i.e. 150℃-180℃. In actual operation, it is heated to 165℃ and needs to be done slowly. During the debonding process, the pipe should be rotated at 30-50 rpm, and in actual operation, it is controlled at 40 rpm. Part of the binder is not removed and seeps out and adheres to the outer surface of the metal particles, which is beneficial to keep the coating intact. At the same time, the solid talc powder helps lubrication; S7: Sintering: To ensure that the metal powder forms an open porous connection shape, the metal powder should obviously be sintered in a solid state; the coated metal powder is quickly heated to 1060℃-1080℃ under the action of the medium-frequency induced current. In actual operation, it is heated to 1060℃, where a small amount of flux doped is melted at high temperature and distributed in the gaps of the metal particles without flowing out and falling off. At the same time, due to the presence of the pore-forming agent, the decomposed hydrogen will escape outward to form pores or remove part of the ash in the gap. In this process, a small amount of residual polymer binder is burned and carbonized to form ash, which is also conducive to the formation of micro-voids; S8: Cooling: After surface sintering, the high alloy steel pipe continuously enters the cooling tunnel for indirect cooling by water cooling jacket. The cooling section, heating section and insulation section are connected tunnels, all of which are protected by argon. When the temperature drops to 400℃, water spray cooling is adopted when exiting the cooling tunnel. After cooling, the straightening equipment is adopted to straighten the pipe. While cooling by water spray, the ash on the sintering surface can be cleaned. The pipe is placed in a multi-probe ultrasonic water tank for cleaning for 30 minutes, which can basically completely remove the clogged ash in the hole. S9: Subsequent treatment: including surface inspection, socket removal, pipe end trimming, and if the surface requirements are strict, the pipe should also be ultrasonically cleaned, pickled, and passivated. During the pickling process, part of the harmful metals added before sintering will be dissolved and removed by the acid; After pickling and passivation, rinse repeatedly with a large amount of water to remove residual acid, then use compressed air to blow repeatedly to remove residual moisture in the holes. Infrared heating plus air blowing can be used for a thorough cleaning. After inspection, qualified porous tubes should be packaged in polyethylene film bags.

[0022] Reference Figure 1-Figure 3 The above-mentioned process for preparing the enhanced heat transfer tube with porous metal coating by sintering method also involves a preparation device, including a shell 1 with two ends connected, and also includes: The outer sides of both ends of the housing 1 are fixedly connected with fixing sleeves 11 .

[0023] The rotating gas ring 2 is installed in both ends of the outer shell 1. The gas path input end of the rotating gas ring 2 is connected with the output end of the external high-pressure argon gas source. The inner circumference of the rotating gas ring 2 rotates coaxially and slidably with the outer circumference of the workpiece 5. The outer shell 1 is connected with an outlet pipe 13.

[0024] Retractable guide rail frames, two guide rail frames are symmetrically distributed at both ends of the shell 1, the top of the guide rail frame is a telescopic section, and the bottom is an elastic section, the input end of the telescopic section is connected to the output end of the rotating air ring 2, and a fixed rod 331 is fixedly connected between the bottom end of the elastic section and the bottom of the shell 1, and the bottom of the workpiece 5 slides coaxially and rotates with the inner circumference of the elastic section.

[0025] Support driving mechanism, multiple support driving mechanisms all include a support rod 4, both ends of the support rod 4 are connected with a driving assembly, the working end of the driving assembly is connected to the guide rail frame at the same end, and is used to drive the support rod 4 to move circumferentially around the guide rail frame, a pneumatic assembly is connected inside the support rod 4, the input end of the pneumatic assembly is connected to the output end of the rotating air ring 2, and the output end is connected to multiple guide wheels 43, some of the guide wheels 43 located in the elastic section are all against the outer side of the bottom of the workpiece 5, a sapphire sensor 34 is installed on the guide rail frame, the sensing end of the sapphire sensor 34 is pressed against the outer side of the workpiece 5 located in the elastic section, and is electrically connected to a controller, the controller is installed on the housing 1, and receives the signal of the sapphire sensor 34 to control the working state of the external high-pressure argon gas source.

[0026] The sapphire sensor 34 is a pressure sensor that can maintain high sensitivity under high temperature and electromagnetic interference conditions.

[0027] Reference Figure 2-Figure 6 The input end of the air circuit of the rotating air ring 2 is a total air inlet 20, and the total air inlet 20 is connected with an inlet pipe 12. The inlet pipe 12 is connected with an output end of an external high-pressure argon gas source at one end away from the rotating air ring 2. A channel for the inlet pipe 12 to pass through is opened on the fixed sleeve 11. The output end of the air circuit of the rotating air ring 2 includes two groups, one group is a double air outlet 201, and the other group is connected with multiple pressure-stabilizing valves 21. The multiple pressure-stabilizing valves 21 correspond one-to-one to the input ends of multiple pneumatic components at the same end. An air pipe 22 is connected between the double air outlet 201 and the input end of the telescopic section and between the pressure-stabilizing valve 21 and the input end of the pneumatic component. The air pipe 22 is made of a hose.

[0028] Reference Figure 3-Figure 7 The guide rail frame includes a rigid outer guide rail 3, a rigid inner guide rail 31, an elastic inner guide rail 32 and an elastic outer guide rail 33. The rigid outer guide rail 3 and the rigid inner guide rail 31 are both retractable structures. The bottom end of the rigid outer guide rail 3 is fixedly connected to the top end of the elastic outer guide rail 33, and they form an outer frame with an upper portion. The bottom end of the rigid inner guide rail 31 is fixedly connected to the top end of the elastic inner guide rail 32, and they form an inner frame with an upper portion being a rectangular frame and a lower portion being a semicircular frame. The inner frame is concentrically arranged in the outer frame, and the bottom of the outer frame is fixedly connected to a fixed rod 331. Multiple driving components are slidably mounted on the inner frame and the outer frame. The inner peripheral side of the elastic inner guide rail 32 slides coaxially with the outer peripheral side of the workpiece 5 and rotates together. The sapphire sensor 34 is installed between the rigid inner guide rail 31 and the elastic inner guide rail 32.

[0029] Reference Figure 8The rigid outer guide rail 3 and the rigid inner guide rail 31 each include two branch rails, the tops of the two branch rails are coaxially slidably sleeved with the same movable guide rail 37, and the bottom ends are fixedly connected to the corresponding elastic inner guide rail 32 and elastic outer guide rail 33, the tops of the two branch rails are fixedly connected with ear plates 36, the opposite sides of the two ear plates 36 are fixedly connected with pistons 361, the outer circumferences of the two pistons 361 are sealed and slidably connected with the same telescopic cylinder 362, and a vent 363 is opened in the middle of the telescopic cylinder 362, and the vent 363 is connected to the double air outlet 201 through the air pipe 22 at one end away from the telescopic cylinder 362.

[0030] Reference Figure 3 , Figure 7 and Fig. 9 The driving assembly includes a limit plate 35, which is fixedly connected to the end of the support rod 4. Two motors 351 are installed on the limit plate 35. The output ends of the two motors 351 are coaxially fixedly connected with rollers 352. Tracks are provided on the inner frame and the outer frame. The two rollers 352 rotate one by one and abut against the adjacent sides of the two tracks at the same end. The two motors 351 are electrically connected to the controller. The controller is used to control the working state of the two motors 351 to make the support rod 4 move circumferentially around the gap between the inner frame and the outer frame.

[0031] Reference Figure 2 , a heating layer 14 is installed on the inner side of the shell 1.

[0032] The heating layer 14 is located in the middle of the housing 1 to reduce the impact of high temperature on the motor 351 and prevent it from failing to work.

[0033] Reference Fig. 9 and Fig.10 The pneumatic component includes an airway, and the two airways are coaxially penetrated and opened on the support rod 4, and are distributed along the vertical line direction of the inner frame and the outer frame. One end of the two airways is a sub-air inlet 41, and the other end is a sub-air outlet 42, and the sub-air inlet 41 and the sub-air outlet 42 on the two airways are arranged in opposite positions, the sub-air inlet 41 is connected with the output end of the pressure regulating valve 21 through the air pipe 22, and the sub-air outlet 42 is connected with the inside of the shell 1, and a plurality of wheel axles 431 are rotatably connected in the support rod 4, and the wheel axles 431 are coaxially fixedly connected with the fan blades 433, and a rotating chamber for the fan blades 433 to rotate is opened in the support rod 4, and the rotating chamber is communicated and cooperated with the two airways, and the ends of the fan blades 433 extend into the two airways, and the wheel axle 431 is sealed and penetrates the support rod 4 near one end of the workpiece 5, and is coaxially fixedly connected with the guide wheel 43.

[0034] The multiple wheel axles 431 on the same support rod 4 are sleeved with the same synchronous belt 44 .

[0035] The wheel shaft 431 extends out of the support rod 4 and one end of the guide wheel 43 is coaxially fixedly connected with a disc, and the disc is rotatably connected to one side close to the guide wheel 43 with two pressing rollers 432 , and the two pressing rollers 432 are pressed against the outer wall of the synchronous belt 44 .

[0036] When the support rod 4 bends with the deformation of the two guide rail frames, the outer wall of the pressing roller 432 is pressed against the outer wall of the synchronous belt 44, pressing the synchronous belt 44 against the inner wall of the axle 431. After the support rod 4 is bent, the synchronous belt 44 can still fit against the inner wall of the axle 431 to achieve the purpose of synchronous speed, so as to better ensure that all guide wheels 43 have the same speed.

[0037] The support rod 4 is a hollow structure with two ends penetrating therethrough. A partition plate 45 is fixedly connected inside the support rod 4 . Two surfaces of the partition plate 45 and the inner circumference of the support rod 4 form two penetrating air passages.

[0038] In the present invention, when the workpiece 5 is rapidly heated by the medium frequency induction current, it enters the device through the through hole in the middle of the rotating air ring 2 to undergo a high temperature sintering process; The external high-pressure argon gas source works, and the high-pressure argon gas is introduced into the rotating gas ring 2 through the inlet pipe 12 and the main gas inlet 20. The argon gas will be divided, and a part of it will enter the telescopic cylinder 362 through the double gas outlet 201 through the gas pipe 22 and the gas vent 363, and the other part will be stabilized into a constant pressure through the pressure-stabilizing valve 21 and then enter the support rod 4 through the gas pipe 22 and the divided gas inlet 41; The workpiece 5 entering is passed through the middle of the irregular ring formed by two symmetrical rigid inner guide rails 31, an elastic inner guide rail 32 and a movable guide rail 37, and is supported and driven by the driven guide wheel 43 on the support rod 4 to slowly pass through the housing 1 from left to right, and is sintered in the process; During the sintering process, there will be melting of the flux aluminum powder and dehydrogenation of titanium dihydride powder to form pores. The molten material produced by aluminum can penetrate into the coating from top to bottom under the action of gravity, making the sintering effect better. Titanium dioxide has a much smaller molecular weight of hydrogen than argon, and can penetrate from the coating from bottom to top under the action of buoyancy to form an open porous structure. Under the control of the controller, the motor 351 works, and its output end drives the roller 352 to rotate, so that the support rod 4 can move at a uniform speed in the closed-loop slide rail formed by the rigid inner guide rail 31, the elastic inner guide rail 32 and the movable guide rail 37, and the slide rail formed by the rigid inner guide rail 31, the elastic inner guide rail 32 and the movable guide rail 37 is at a constant distance from the slide rail formed by the rigid outer guide rail 3, the elastic outer guide rail 33 and the movable guide rail 37, and the roller 352 on the limit plate 35 is respectively installed in the tracks of the above two closed-loop slide rails, so that when the support rod 4 moves along the slide rail, it can be ensured that it also moves, that is, when the support rod 4 moves in the elastic inner guide rail 32 and the elastic outer guide rail 33, it can be ensured that the side end face of the guide wheel 43 is always in contact with the workpiece 5 to achieve a better support and auxiliary movement effect, so that the outer end face of the lower half of the workpiece 5 is always supported by the guide wheel 43, and the workpiece 5 will also rotate with the movement of the support rod 4; When the support rod 4 moves to the junction of the rigid inner guide rail 31 and the elastic inner guide rail 32, and the rigid outer guide rail 3 and the elastic outer guide rail 33, the curvature of the track will change. At this time, the support rod 4 will slide vertically upward along the closed-loop slide rail. Since the curvature is different from the curvature of the outer wall of the workpiece 5, the contact and support of the guide wheel 43 with the workpiece 5 will stop and move away from the workpiece 5 after passing the junction, that is, the upper half surface of the workpiece 5 will not be contacted by the guide wheel 43, so that the decomposed hydrogen can be better overflowed to form an open porous structure to increase the porosity of the coating, and avoid the pressure and obstruction of the guide wheel 43 that will cause the hydrogen to be unable to overflow and increase the probability of structural formation failure; A sapphire sensor 34 is installed on the other side of the middle connection between the rigid inner guide rail 31 and the elastic inner guide rail 32. The sapphire sensor 34 is close to the workpiece 5, and the sensing end of the sapphire sensor 34 is kept level with the outermost point of the guide wheel 43. Therefore, the pressure of the sapphire sensor 34 on the workpiece 5 is the pressure applied by the end face of the guide wheel 43 to the workpiece 5. When the temperature change during the sintering process causes the workpiece 5 to shrink, thereby causing the guide wheel 43 to be unable to fit the workpiece 5, the sapphire sensor 34 senses that the pressure has decreased and will send an electrical signal. The controller receives this signal and controls the external high-pressure argon gas source to reduce the pressure of the argon gas introduced, thereby reducing the pressure in the telescopic cylinder 362. Under the action of the pressure-stabilizing valve 21, the air pressure of the gas introduced into the support rod 4 remains stable. Since the elastic inner guide rail 32 and the elastic outer guide rail 33 are elastic, the elastic inner guide rail 32 and the elastic outer guide rail 33 recover after slight deformation. The reduced pressure in the telescopic cylinder 362 will cause the rigid outer guide rail 3 and the rigid inner guide rail 31 to shrink toward the center along the movable guide rail 37, thereby allowing the sapphire sensor 34 to fit onto the workpiece 5 again, thereby ensuring that the end face of the guide wheel 43 is always in contact with the workpiece 5, thereby preventing the workpiece 5 from shaking or failing to rotate in the workpiece due to non-fitting. The gas introduced into the sub-inlet 41 through the pressure-stabilizing valve 21 will push the fan blade 433 to rotate clockwise along the axis of the wheel shaft 431 in the support rod 4, thereby pushing the guide wheel 43 to rotate clockwise. At the same time, due to the existence of the synchronous belt 44, the movement of multiple guide wheels 43 will be synchronized so that the movement speed of each guide wheel 43 is the same, thereby avoiding that due to the different movement speeds of the guide wheels 43 and the constant forward speed of the workpiece 5, a part of the guide wheels 43 and the workpiece 5 will slide relative to each other. At this time, it is sliding friction rather than rolling friction, which will make it easier for the open porous structure formed by the coating to be destroyed due to friction, thereby causing the porosity to decrease. After driving the guide wheel 43 to rotate, the argon gas will be discharged from the gas outlet 42 and fill the entire device to protect sintering and prevent hydrogen combustion and explosion. At the same time, it can also bring the heat near the motor 351 back to the center and finally be discharged from the outlet pipe 13 together with the hydrogen, completing the protection of the sintering process.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing a heat transfer tube with a porous metal coating by sintering, characterized in that: The following steps are involved: S1: Surface pretreatment of the base tube: solvent cleaning combined with mechanical polishing and hot air blowing to remove residual oil, scale and paint on the surface of the tube, i.e. the processed part (5); S2: Roughening of the base tube surface: On a special tube shot blasting machine or shot peening machine, the tubes are processed in batches by using shot peening or shot peening technology to make the surface of the tube reach a certain roughness; S3: Apply adhesive: Apply a layer of adhesive evenly on the surface of the roughened metal pipe by spraying or roller brushing for 2 times, and let it dry naturally or air dry for 2 hours; the adhesive is liquid silica sol; S4: Mixing and granulating metal powder raw materials: mainly metal powder, binder, lubricant, and other additives; they need to be mixed, stirred, and evenly dispersed in a cylindrical rotary mixer, and cooled to form mixed particles after discharge. The metal powder is first heated to 110-130°C, and then these raw materials are weighed and added to the mixer, stirred for 10-15 minutes, so that the metal powder is coated with a layer of organic film; S5: Injection molding: Use a twin-screw injection molding machine to heat and extrude the mixed particles into a special mold. At this time, the pipe passes through the mold at a uniform speed, and the melted and extruded mixture continuously and evenly covers the surface of the pipe to form a uniform outer skin. During injection molding, the metal coating reserves a thickness margin; S6: Debonding: remove part of the polymer binder in the injection mixture to maintain the metal powder structure. The debonding method uses low-temperature heating, i.e. 150°C-180°C, and slowly heats. During the debonding process, the pipe should be kept at 30-50 rpm. Part of the binder is not removed and seeps out and adheres to the outer surface of the metal particles. S7: Sintering: Ensure that the metal powder forms an open porous connection shape, so that the metal powder forms solid sintering; under the action of medium frequency induction current, the coated metal powder is quickly heated to 1060℃-1080℃, wherein the doped flux is melted at high temperature and distributed in the gaps of the metal particles. At the same time, due to the presence of the pore-forming agent, the decomposed hydrogen will escape outward to form pores or remove part of the ash in the gaps; S8: Cooling: After surface sintering, the pipes continuously enter the cooling tunnel for water cooling. The cooling section, heating section and insulation section are connected tunnels, all of which are protected by argon gas. When the temperature drops below 400°C, the pipes are cooled by water spray when they leave the cooling tunnel. After cooling, the pipes are straightened by straightening equipment. S9: Subsequent treatment: Surface inspection of the pipe, removal of the nipple, trimming of the pipe end, ultrasonic cleaning, pickling and passivation of the pipe; The above-mentioned process for preparing the enhanced heat transfer tube with porous metal coating by sintering method also involves a preparation device, including a shell (1) with two ends connected, and also including: A rotating gas ring (2), wherein both ends of the housing (1) are provided with a rotating gas ring (2), the gas path input end of the rotating gas ring (2) is connected to the output end of an external high-pressure argon gas source, the inner circumference of the rotating gas ring (2) rotates coaxially with the outer circumference of the workpiece (5) and is slidably matched, and the housing (1) is connected to an outlet pipe (13); A heating layer (14), the heating layer (14) being mounted on the inner side of the housing (1); A retractable guide rail frame, wherein the two guide rail frames are symmetrically distributed at both ends of the housing (1), the top of the guide rail frame is a telescopic section, and the bottom is an elastic section, the input end of the telescopic section is connected to the output end of the rotating air ring (2), a fixed rod (331) is fixedly connected between the bottom end of the elastic section and the bottom of the housing (1), and the bottom of the workpiece (5) slides coaxially with the inner circumference of the elastic section and rotates in coordination; A support drive mechanism, wherein the plurality of support drive mechanisms each comprise a support rod (4), both ends of the support rod (4) being connected to a drive assembly, the working end of the drive assembly being connected to a guide rail frame at the same end and being used to drive the support rod (4) to move circumferentially around the guide rail frame, the support rod (4) being connected to a pneumatic assembly, the input end of the pneumatic assembly being connected to an output end of a rotating air ring (2), and the output end being connected to a plurality of guide wheels (43), the guide wheels (43) located in the elastic section being pressed against the outer side of the bottom of the workpiece (5), the guide rail frame being mounted with a sapphire sensor (34), the sensing end of the sapphire sensor (34) being pressed against the outer side of the workpiece (5) located in the elastic section, and being electrically connected to a controller, the controller being mounted on the housing (1) and receiving a signal from the sapphire sensor (34) to control the working state of an external high-pressure argon gas source.

2. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 1, characterized in that: Fixed sleeves (11) are fixedly connected to the outer sides of both ends of the housing (1).

3. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 2, characterized in that: The air path input end of the rotating air ring (2) is a total air inlet (20), the total air inlet (20) is connected to an inlet pipe (12), the inlet pipe (12) is connected to an output end of an external high-pressure argon gas source at one end away from the rotating air ring (2), the fixed sleeve (11) is provided with a passage for the inlet pipe (12) to pass through, the air path output end of the rotating air ring (2) comprises two groups, one group is a double air outlet (201), and the other group is connected to a plurality of pressure-stabilizing valves (21), the plurality of pressure-stabilizing valves (21) correspond one to one with a plurality of pneumatic component input ends at the same end, the double air outlet (201) and the telescopic section input end and the pressure-stabilizing valve (21) and the pneumatic component input end are both connected to an air pipe (22), the air pipe (22) is made of a hose.

4. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 3, characterized in that: The guide rail frame comprises a rigid outer guide rail (3), a rigid inner guide rail (31), an elastic inner guide rail (32) and an elastic outer guide rail (33); the rigid outer guide rail (3) and the rigid inner guide rail (31) are both retractable structures; the bottom end of the rigid outer guide rail (3) is fixedly connected to the top end of the elastic outer guide rail (33) to form an outer frame having a rectangular frame at the top and a semicircular frame at the bottom; the bottom end of the rigid inner guide rail (31) is fixedly connected to the top end of the elastic inner guide rail (32) to form an inner frame having a rectangular frame at the top and a semicircular frame at the bottom; the inner frame is concentrically arranged in the outer frame; the bottom of the outer frame is fixedly connected to a fixed rod (331); a plurality of the drive assemblies are slidably mounted on the inner frame and the outer frame; the inner peripheral side of the elastic inner guide rail (32) is coaxially slidable and rotationally matched with the outer peripheral side of the workpiece (5); and the sapphire sensor (34) is mounted between the rigid inner guide rail (31) and the elastic inner guide rail (32).

5. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 4, characterized in that: The rigid outer guide rail (3) and the rigid inner guide rail (31) each comprise two support rails, the tops of the two support rails being coaxially slidably sleeved with the same movable guide rail (37), and the bottoms being fixedly connected to the corresponding elastic inner guide rail (32) and the elastic outer guide rail (33), the tops of the two support rails being fixedly connected with ear plates (36), the opposite sides of the two ear plates (36) being fixedly connected with pistons (361), the outer circumferences of the two pistons (361) being sealingly slidably connected with the same telescopic cylinder (362), the middle of the telescopic cylinder (362) being provided with an air vent (363), the air vent (363) being connected to the double air outlets (201) via an air pipe (22) at one end away from the telescopic cylinder (362).

6. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 4, characterized in that: The driving assembly comprises a limit plate (35), the limit plate (35) being fixedly connected to the end of the support rod (4), two motors (351) being mounted on the limit plate (35), the output ends of the two motors (351) being coaxially fixedly connected to rollers (352), the inner frame and the outer frame being provided with tracks, the two rollers (352) being rotated one by one correspondingly against adjacent sides of two tracks at the same end, the two motors (351) being electrically connected to a controller, the controller being used to control the working state of the two motors (351) so that the support rod (4) moves circumferentially around the gap between the inner frame and the outer frame.

7. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 4, characterized in that: The pneumatic assembly comprises an air passage, wherein the two air passages are coaxially penetrated and opened on the support rod (4) and are distributed along the vertical line direction of the inner frame and the outer frame, one end of the two air passages is a branch air inlet (41), and the other end is a branch air outlet (42), and the branch air inlet (41) and the branch air outlet (42) on the two air passages are arranged in opposite positions, the branch air inlet (41) is connected to the output end of the pressure regulating valve (21) through the air pipe (22), and the branch air outlet (42) is connected to the outer shell (1 ), a plurality of axles (431) are rotatably connected in the support rod (4), a fan blade (433) is coaxially fixedly connected to the axle (431), a rotation chamber for the fan blade (433) to rotate is provided in the support rod (4), the rotation chamber is communicated with and cooperates with the two air passages, the ends of the fan blade (433) extend into the two air passages, the axle (431) is sealed and penetrates the support rod (4) at one end close to the workpiece (5), and is coaxially fixedly connected to the guide wheel (43).

8. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 7, characterized in that: The plurality of wheel axles (431) located on the same support rod (4) are sleeved with the same synchronous belt (44).

9. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 8, characterized in that: The wheel axle (431) extends out of the support rod (4) and one end of the guide wheel (43) is coaxially fixedly connected to a disc, and the disc is rotatably connected to two pressing rollers (432) on the side close to the guide wheel (43), and the two pressing rollers (432) are pressed against the outer wall of the synchronous belt (44).

10. The process for preparing a heat transfer tube enhanced by sintering a porous metal coating according to claim 7, characterized in that: The support rod (4) is a hollow structure with two ends penetrating therethrough. A partition plate (45) is fixedly connected inside the support rod (4). Two surfaces of the partition plate (45) and the inner circumference of the support rod (4) form two penetrating air passages.

Images