Aerospace ultra-thin-wall stainless steel seamless pipe and multi-stage heat treatment preparation equipment thereof

Abstract

The application discloses an aerospace ultra-thin-wall stainless steel seamless pipe and a multistage heat treatment preparation equipment thereof, relates to the technical field of metal pipe heat treatment, and is used for improving the problem of excessive axial temperature difference of long pipe material during cross-furnace heat treatment on a compact layout production line, thereby improving the physical performance of the pipe material under high-temperature conditions and reducing the production difficulty. The equipment comprises a plurality of heat treatment furnaces arranged along a conveying direction, a conveyor penetrating through the heat treatment furnaces, and a transfer box used for bearing the pipe material. Ventilation channels and opening and closing mechanisms for controlling the opening and closing of the ventilation channels are arranged on the box body of the transfer box. The conveyor is fixed with a guide structure at a position corresponding to a middle section area of the heat treatment furnace. When the transfer box moves out of the furnace body, the opening and closing mechanisms are reset to close the ventilation channels under the action of gravity, so that the transfer box is in a relatively closed state when moving in the gap between the furnaces, heat loss of the pipe material is reduced, the axial temperature uniformity of the pipe material is improved, and the tensile strength, yield strength and hardness of the steel grade are improved.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for metal tubes, and in particular to an ultra-thin-walled stainless steel seamless tube for aerospace applications and its multi-stage heat treatment preparation equipment. Background Technology

[0002] As a core load-bearing component of hydraulic systems and environmental control pipelines, ultra-thin-walled stainless steel seamless pipes have stringent requirements for dimensional accuracy, microstructure uniformity, and surface quality. Multi-stage heat treatment is used to control the metallographic structure of the pipe, eliminate cold working, and improve the tensile strength, yield strength, and hardness of the steel. In current industrial production and aerospace, multi-stage heat treatment of this type of pipe generally adopts a continuous production line layout. This means that multiple independent temperature-controlled and atmosphere-controlled heat treatment furnaces are arranged sequentially along the pipe conveying direction. A roller conveyor mechanism drives the material rack or box carrying the pipe to move at a uniform speed, so that the pipe passes through different process temperature zones in sections, thereby achieving continuous batch production. However, in some applications with limited factory space, the transition distance between adjacent heat treatment furnaces is often compressed due to site layout constraints. Since aerospace stainless steel seamless tubes are mostly long-length specifications, tubes are prone to cross-furnace conditions when transported on such compact production lines. The front end of the tube has entered the furnace of the next temperature zone, while the tail end remains in the temperature field environment of the preceding furnace. Under this condition, different sections of the tube will be briefly exposed to two significantly different temperature environments. In addition to causing uneven axial temperature gradients, additional thermal stress will be generated inside the tube. For tubes with extremely thin walls and weak radial rigidity, this can easily exacerbate their thermal deformation tendency, causing straightness and roundness accuracy to exceed tolerances. This not only makes the production of such ultra-thin-walled tubes extremely difficult, but also leads to inconsistent microstructural transformation processes in different sections, severely restricting the physical properties of the tube under high-temperature conditions, and ultimately affecting the uniformity of the overall performance and long-term service reliability of the tube. Summary of the Invention

[0003] This invention addresses the problem of excessive axial temperature difference during the transport of long, ultra-thin-walled stainless steel tubes across furnaces in compact continuous heat treatment production lines, which easily leads to thermal deformation and uneven microstructure. During the research and development process, it was found that existing technologies using fixed furnace insulation covers only achieve localized passive insulation and cannot provide synchronous protection along with the tubes, resulting in significant temperature differences between the beginning and end of long tubes when transporting them across furnaces. Furthermore, heat treatment material baskets with openable / closable structures are mostly driven by cylinders, requiring additional power and control systems, and exhibiting extremely high failure rates under high-temperature and dusty conditions, making them unsuitable for long-cycle continuous production.

[0004] This invention organically integrates an openable and closable multi-faceted ventilation duct transfer box system, a guide-triggered automatic opening and closing subsystem, and an end sealing plate synchronous linkage subsystem. Through the reuse of conveying power and gravity reset, it realizes the automatic switching of the entire process of fully open heat exchange in the furnace and sealed heat preservation between furnaces, providing an aerospace-grade ultra-thin-walled stainless steel seamless tube and its multi-stage heat treatment preparation equipment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An ultra-thin-walled stainless steel seamless tube for aerospace applications includes an integrally formed stainless acid-resistant steel tube body. The tube body has a long, straight, seamless tubular structure and an ultra-thin-walled configuration. The entire tube conforms to the rating standards of GB / T3089-2020 for ultra-thin-walled stainless steel seamless tubes.

[0006] A multi-stage heat treatment preparation apparatus for preparing the aforementioned aerospace-grade ultra-thin-walled stainless steel seamless tube, comprising: Multiple heat treatment furnaces arranged in sequence, each heat treatment furnace including a furnace body and an upper chamber and a lower chamber located on the upper and lower layers of the furnace body, respectively; A conveyor is arranged along the direction of multiple furnace bodies. The conveyor includes a frame and multiple rotating conveying rollers that are equidistantly distributed along the length of the frame. A transfer box is used to load seamless tube bodies. The transfer box includes a box body and an openable and closable channel on the surface of the box body. The openable and closable channel includes two upper ventilation channels respectively opened on the top two sides of the box body and two side ventilation channels respectively opened on the side walls of the box body. An openable and closable upper partition is provided in the upper ventilation channel, and an openable and closable side partition is provided in the side ventilation channel. The transfer box also includes a guide structure for controlling the opening and closing of the upper and side partitions.

[0007] In one possible design, both ends of the furnace body are provided with passage openings to make the upper and lower chambers open structures; Both ends of the box body are fixedly provided with baffles, and the surface of the baffles has openings that communicate with the box body cavity.

[0008] In one possible design, the upper partition is fixedly provided with a rotating shaft along its length, and the rotating shaft is located at a non-central position along the width of the upper partition. Both ends of the rotating shaft are rotatably configured to rotatably align with the inner wall of the upper ventilation duct. The side partition is slidably installed up and down along the height direction of the side ventilation duct.

[0009] In one possible design, cavities are provided on both sides of the outer side of one end of the box body. The guide structure includes connecting ring seat I and connecting ring seat II disposed inside the cavities, and a guide block disposed inside the frame and cooperating with connecting ring seat II. One end of the rotating shaft extends to the upper part of the cavity on the same side. The connecting ring seat I is fixedly sleeved on the outer wall of the rotating shaft. The outer wall of the connecting ring seat I is provided with a protruding end I. The connecting ring seat II is rotatably disposed at the lower part of the cavity. The outer wall of the connecting ring seat II is provided with protruding ends II and III respectively. Connecting shafts are fixedly disposed on the side walls of both protruding ends I and II. The outer walls of the two connecting shafts are rotatably sleeved with the same connecting arm. The guide block is fixedly disposed on the side wall of the frame. The bottom wall of the cavity has an opening that communicates with the outside. The protruding end III extends to the outside through the opening and cooperates with the guide surfaces on both sides of the side wall of the guide block. The guide structure also includes an inclined push seat disposed on the side wall of the side partition and a top seat disposed in the frame. The inclined push seat is fixedly disposed on the side wall of the side partition and is inclined. The top seat is fixedly disposed on the side wall of the frame, and the top of the top seat is provided with an inclined push surface for cooperating with the inclined push seat.

[0010] In one possible design, an upper limit plate and a lower limit plate are fixedly installed on the upper and lower sides of the upper ventilation duct, respectively, away from each other. The top and bottom of the upper partition are respectively provided with an upper concave surface and a lower concave surface, which cooperate with the upper limit plate and the lower limit plate respectively. The side wall of the box body is provided with a clearance groove that is connected to the side ventilation channel and cooperates with the inclined push seat.

[0011] In one possible design, the transfer box further includes two lifting and closing sealing plates, which are slidably disposed on the side of the opening to close it. The bottom of the box body has a groove, and a connecting frame is slidably disposed inside the groove. The end of the connecting frame is fixedly disposed with the sealing plate on the same side. The outer wall of the conveying roller is fixedly fitted with a top ring corresponding to the groove.

[0012] In one possible design, limiting rings for limiting the box body are fixedly fitted on both sides of the outer wall of the conveying roller, and a hanging ring is fixedly installed on the top of the box body.

[0013] In this application, during actual use, the sealing plate naturally slides down by gravity, making the transfer box open. The seamless tube is installed into the interior of the transfer box through the opening, and the assembled transfer box is hoisted onto the conveyor by equipment such as a crane. The transfer box is located between the limiting rings on both sides to ensure stability during transportation. At the same time, the top ring will be inside the groove, thereby pushing the connecting frame to move the sealing plate upward, so that when the transfer box is hoisted onto the conveyor, the baffles on both sides will automatically close. The transfer box is conveyed and transferred via a conveyor. When the transfer box moves into the middle of any heat treatment furnace, its bottom protrusion III will abut against the guide surface of the guide block, thereby pushing protrusion III to rotate along its connecting shaft. Through the connection arm, it drives the connecting ring seat I to rotate synchronously. The connecting ring seat I will drive the upper partition to rotate through the rotating shaft, thereby opening the upper ventilation channel. At the same time, the top of the inclined push surface will abut against the bottom surface of the inclined push seat, thereby pushing the side partition to move upward and opening the side ventilation channel. This allows the transfer box carrying the seamless tube to enter the middle of one of the heat treatment furnaces. When the conveyor leaves the center of the heat treatment furnace, causing the transfer box to leave the guide block and top seat, the side partition will automatically fall to close the side ventilation channel, and the upper partition will automatically rotate to close by gravity. The upper concave surface and the lower concave surface will contact the upper limit plate and the lower limit plate respectively, so as to reduce the heat change around the seamless tube during the process of entering the next heat treatment furnace. When it enters the center of the next heat treatment furnace, it will automatically open again to reduce the impact of different heating temperatures on the front and rear sections of the seamless tube. After the transfer box carrying the seamless tube has been moved to the end of the conveyor and completed the heat treatment, the conveyor can be transferred here by equipment such as a crane. When the transfer box is removed from the conveyor, the sealing plate will fall automatically by gravity, thereby opening the opening.

[0014] In this invention, the opening and closing of the ventilation duct is achieved through the linkage between the mechanical structure and the conveying process, without the need for additional power or control. The action process is synchronized with the heat treatment process, which facilitates its integration and application on a continuous production line. In this invention, the multi-stage heat treatment preparation equipment has openings at both ends of the transfer box that can be opened and closed by sealing plates. This opening and closing action is triggered by the structure on the conveying equipment, which facilitates the automatic opening of the openings for loading and unloading pipes at the loading and unloading station, and the automatic closing of the openings during the conveying and heat treatment process. This simplifies the operation steps, eliminates the need for manual opening and closing of the end caps, and improves the operating efficiency of single-batch production. During the conveying and heat treatment process, the sealing plates are automatically closed by the push of the top ring, forming a relatively sealed containment space together with the closed upper and side ventilation channels. This blocks the heat convection and heat radiation loss path at the end of the pipe, enhances the heat preservation effect during the furnace transition stage, and at the same time prevents external dust and debris from falling into the box during the conveying process and contaminating the surface of the pipe, ensuring the surface smoothness and processing quality of the pipe. In this invention, during use, the ventilation duct and its opening and closing mechanism set on the transfer box, together with the guide structure on the conveying path, ensure that the pipe only exchanges heat with the furnace atmosphere in the high-temperature section inside the heat treatment furnace. When moving between adjacent furnace bodies, the transfer box is in a relatively sealed state, thereby improving the problem of excessive temperature difference between the two ends of the long pipe caused by the compact layout. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of a multi-stage heat treatment preparation equipment for ultra-thin-walled stainless steel seamless tubes for aerospace applications proposed in this invention. Figure 2 This is a partial structural schematic diagram of a multi-stage heat treatment preparation device for ultra-thin-walled stainless steel seamless tubes for aerospace applications proposed in this invention. Figure 3 For the present invention Figure 1 Enlarged view of the structure of section A; Figure 4 For the present invention Figure 2 Enlarged view of the structure of section B; Figure 5 For the present invention Figure 2 Enlarged view of the structure of section C; Figure 6 This is a schematic diagram of the transfer box structure of a multi-stage heat treatment preparation equipment for ultra-thin-walled stainless steel seamless tubes for aerospace applications proposed in this invention. Figure 7 This is a schematic diagram of the exploded structure of the transfer box of a multi-stage heat treatment preparation equipment for ultra-thin-walled stainless steel seamless tubes for aerospace applications, as proposed in this invention. Figure 8 For the present invention Figure 7 Enlarged view of the structure of part D in the middle.

[0016] In the diagram: 1. Heat treatment furnace; 111. Furnace body; 112. Upper chamber; 113. Passageway opening; 114. Lower chamber; 2. Conveyor; 211. Frame; 212. Conveyor roller; 213. Top ring; 214. Limiting ring; 3. Transfer box; 311. Box body; 312. Hanging ring; 313. Upper partition; 3131. Upper concave surface; 3132. Lower concave surface; 314. Sealing plate; 315. Baffle; 316. Connecting frame; 317. Groove; 318. Opening; 319. Rotating shaft; 320. Upper ventilation duct; 3201. Upper limit plate; 3202. Lower limit plate; 321. Side ventilation duct; 322. Relief groove; 323. Side partition; 324. Inclined push seat; 325. Chamber; 3251. Through port; 326. Connecting ring seat I; 3261. Protruding end I; 327. Connecting shaft; 328. Connecting arm; 329. Connecting ring seat II; 3291. Protruding end II; 3292. Protruding end III; 4. Guide block; 411. Guide surface; 5. Top seat; 511. Inclined push surface. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] In one embodiment: an ultra-thin-walled stainless steel seamless tube for aerospace applications, rated according to technical standard GB / T3089-2020 for ultra-thin-walled stainless steel seamless tubes.

[0019] refer to Figure 1 A multi-stage heat treatment preparation equipment for stainless steel seamless tubes, the equipment mainly includes multiple heat treatment furnaces 1 arranged in sequence, a conveyor 2 arranged along the furnace row direction, and a transfer box 3 for loading seamless tubes.

[0020] refer to Figure 2-5 Multiple heat treatment furnaces 1 are arranged in a straight line. The spacing between adjacent furnace bodies 111 is set according to the site conditions. The furnace body 111 of the heat treatment furnace 1 is divided into an upper chamber 112 and a lower chamber 114. Both ends of the furnace body 111 along the conveying direction are provided with passage openings 113 that pass through the upper and lower chambers, so that the upper chamber 112 and the lower chamber 114 form an open structure at both ends. The upper chamber 112 is the high-temperature heat treatment zone, and the lower chamber 114 is used to arrange some conveying and control mechanisms.

[0021] The conveyor 2 is a roller conveyor, and its frame 211 is fixedly installed on the ground or foundation and runs through the lower chamber 114 of all heat treatment furnaces 1. On the frame 211, multiple driveable rotating conveyor rollers 212 are distributed at equal intervals along its length. The conveyor rollers 212 are rotatably connected to the frame 211 through bearings. On both sides of the outer wall of the conveyor roller 212, limiting rings 214 are fixedly fitted by interference fit or welding. The area between the two limiting rings 214 is used to accommodate and limit the transfer box 3. In the middle section of the outer wall of the conveyor roller 212, a top ring 213 is also fixedly installed.

[0022] refer to Figure 6-8 The transfer box 3 is used to carry one or more ultra-thin-walled stainless steel seamless tubes for aerospace applications. The main body of the transfer box 3 is a square box body 311. Both ends of its length are welded and fixed with baffles 315. A rectangular opening 318 is opened in the center of the baffle 315. The opening 318 is connected to the internal cavity of the box body 311 and serves as a channel for loading and unloading seamless tubes. On both sides of the top of the box body 311, there are long strip-shaped upper ventilation channels 320. On both sides of the side walls of the box body 311, there are vertical side ventilation channels 321. Both the upper ventilation channels 320 and the side ventilation channels 321 are connected to the internal cavity of the box body 311.

[0023] To control the opening and closing of the ventilation duct, an upper partition 313 is provided in the upper ventilation duct 320. A rotating shaft 319 is fixedly connected to the upper partition 313 along its length. The axis of the rotating shaft 319 is located off-center in the width of the upper partition 313 and is biased to one side. The end of the rotating shaft 319 is rotatably connected to the side wall of the upper ventilation duct 320. A side partition 323 that can slide up and down along its height is provided in the side ventilation duct 321. An inclined push seat 324 is welded and fixed on the plate surface of the side partition 323 facing the outside of the box body 311. The inclined push seat 324 is set at an angle to the horizontal plane. A clearance groove 322 is provided on the side wall of the box body 311 so that the inclined push seat 324 can pass through when it moves up with the side partition 323.

[0024] To automatically control the opening and closing of the upper partition 313 and the side partition 323 during the conveying process, a guide structure is provided on the transfer box 3. Part of the guide structure is integrated into two cavities 325 outside one end of the box body 311. The cavity 325 is formed by a cover welded to the end of the box body 311, and its inner wall is provided with a ceramic fiber heat insulation layer to reduce the impact of the high temperature of the upper chamber 112 of the heat treatment furnace on the internal mechanism. Above the interior of the cavity 325, the end of the rotating shaft 319 extends into and is fixedly fitted with a connecting ring seat I 326. The outer edge of the connecting ring seat I 326 is provided with a radially protruding convex end I 32. 61. Inside the cavity 325, a connecting ring seat II 329 is rotatably provided via a bearing. The outer edge of the connecting ring seat II 329 has two radially protruding protrusions, namely protrusion II 3291 and protrusion III 3292. The sides of protrusion I 3261 and protrusion II 3291 are fixed with connecting shafts 327. Connecting arms 328 are rotatably sleeved on the two connecting shafts 327, thereby hinged and linked connecting ring seat I 326 and connecting ring seat II 329. The bottom wall of the cavity 325 has an opening 3251, through which protrusion III 3292 passes downward and is exposed to the outside.

[0025] Another part of the guide structure is fixed on the frame 211 of the conveyor 2. On the side of the frame 211 corresponding to the middle section of the heat treatment furnace 1 in the length direction, a guide block 4 is fixedly installed. The side of the guide block 4 has two inclined guide surfaces 411. These two guide surfaces 411 are arranged in a figure-eight shape. When the transfer box 3 moves with the conveyor 2 to the middle of the heat treatment furnace 1, the protruding end Ⅲ 3292 at its bottom will enter the area of ​​the guide block 4 and contact the guide surface 411. In addition, on the frame 211 of the guide block 4 along the conveying direction, a top seat 5 is fixedly installed. The top of the top seat 5 has an inclined push surface 511.

[0026] In this embodiment, upper limit plate 3201 and lower limit plate 3202 are welded to the inner walls of the upper and lower sides of the upper ventilation duct 320, and near its end. The top and bottom of the upper partition plate 313 are respectively machined with upper concave surface 3131 and lower concave surface 3132. When the upper partition plate 313 naturally hangs down to the closed position under the action of gravity, its upper concave surface 3131 is in line contact with the upper limit plate 3201, and its lower concave surface 3132 is in line contact with the lower limit plate 3202.

[0027] A thermal expansion gap is reserved at the rotational engagement point between the rotating shaft 319 and the inner wall of the upper ventilation duct 320. The side of the side partition 323 is embedded in the guide groove, and a thermal expansion sliding gap is reserved between the side partition 323 and the guide groove to avoid motion jamming caused by high temperature thermal deformation.

[0028] The box body 311, upper partition 313, side partition 323, connecting ring seat and rotating shaft 319 are all made of 310S heat-resistant stainless steel, and the ceramic fiber heat insulation layer of the inner wall of the cavity 325 is made of alumina fiber.

[0029] In the initial state, the openings 318 on both sides of the transfer box 3 are open. The ultra-thin wall stainless steel seamless tube is horizontally inserted into the box body 311 through the opening 318. Using equipment such as a crane, the transfer box 3 is lifted to the starting end of the conveyor 2 through the hanging ring 312 on the top of the box body 311 and placed between the two limiting rings 214. During the placement process, the top ring 213 on the conveying roller 212 will be embedded in the preset groove 317 at the bottom of the box body 311. The conveyor 2 is started, and the conveyor roller 212 rotates, driving the transfer box 3 to enter each heat treatment furnace 1 in sequence. When the transfer box 3 moves into the middle section of the length direction inside any heat treatment furnace 1, the protruding end III 3292 at its bottom will contact the guide surface 411 of the guide block 4 fixed there. As the transfer box 3 continues to move forward, the guide surface 411 forces the protruding end III 3292 to move inward, driving the connecting ring seat II 329 to rotate. The connecting ring seat II 329 pulls the connecting ring seat I 326 to rotate synchronously through the connecting arm 328 and the connecting shaft 327. The connecting ring seat I 326 then drives the rotating shaft 319 and the upper partition 313 to rotate, thereby opening the upper ventilation duct 320. At the same time, the top seat 5 fixed in this area will have its inclined push surface 511 contacting the bottom surface of the inclined push seat 324 on the side of the transfer box 3. As the transfer box 3 moves forward, the inclined push surface 511 pushes the inclined push seat 324 upward, thereby causing the side partition 323 to slide upward within the side ventilation channel 321, opening the side ventilation channel 321. At this point, the transfer box 3 is fully open in the high-temperature zone of the heat treatment furnace 1, and the hot air flow inside the furnace can exchange heat with the seamless tube through the upper ventilation channel 320 and the side ventilation channel 321; When the transfer box 3 moves out of the middle section of the heat treatment furnace 1 and is about to enter the furnace gap, the protruding end III 3292 disengages from the guide block 4, and the inclined push seat 324 also moves past the top seat 5. After losing the external force, the side partition 323 slides down and resets along the side ventilation channel 321 under the action of gravity, closing the side ventilation channel 321. The upper partition 313 also rotates around the eccentrically set rotating shaft 319 under the action of gravity until the upper concave surface 3131 and the lower concave surface 3132 contact the upper limit plate 3201 and the lower limit plate 3202 respectively, closing the upper ventilation channel 320. At this time, the transfer box 3 is in a relatively sealed state. During the short period of movement between the furnaces, the relatively sealed transfer box 3 can reduce the heat loss rate of the seamless tube, thereby reducing the problem of excessive temperature difference at both ends of the seamless tube due to the short furnace gap, and reducing the risk of surface oxidation. After the transfer box 3 enters the next heat treatment furnace 1, the process of steps 2 and 3 is repeated to achieve heat treatment at different stages of the process. After all heat treatment processes are completed, the transfer box 3 is transported to the end, and the crane lifts it off the conveyor 2. When the groove 317 at the bottom of the box body 311 is disengaged from the top ring 213, the mechanism connected to the sealing plate 314 is released, and the openings 318 on the side baffles 315 are opened, so that the processed seamless tube can be taken out.

[0030] Compared with existing continuous heat treatment production lines, this solution, through an openable and closable transfer box structure, achieves a zoned thermal management mode of open heat exchange inside the furnace and closed insulation between furnaces. In a compact multi-furnace continuous production line, the transfer box is in a relatively closed state during the cross-furnace transport of long-length tubes. This reduces the intensity of convective heat transfer between the tube surface and the outside air, effectively reduces the axial temperature difference between the front and rear ends of the tube, and weakens the additional thermal stress caused by the cross-furnace temperature difference. For aerospace stainless steel tubes with extremely thin walls and weak radial deformation resistance, the reduction of axial temperature difference can directly reduce the risk of thermal deformation and ensure that the tube's straightness, roundness, and other dimensional and positional tolerances meet high-precision requirements. More importantly, through a refined closed insulation design, this equipment effectively eliminates the adverse effects of residual stress from cold working and improves the tensile strength, yield strength, and hardness of this steel grade, significantly improving the physical properties of the tube under high-temperature conditions. Meanwhile, the fully integrated mechanized opening and closing method requires no additional control, which greatly reduces the production difficulty of aerospace-grade ultra-thin-walled pipes. It also avoids the problem of inconsistent microstructure transformation processes in different shaft sections, improves the uniformity of the overall mechanical properties and batch stability of the pipe, and extends the long-term service life of the pipe in hydraulic and environmental control systems.

[0031] This application can be used in the field of heat treatment of metal pipes, or in other fields applicable to this application.

[0032] In another embodiment: Reference Figure 6A multi-stage heat treatment preparation device for ultra-thin-walled stainless steel seamless tubes for aerospace applications is used in the field of metal tube heat treatment. The structure of this embodiment is basically the same as that of the previous embodiment, except that the automatic opening and closing structure of the openings 318 at both ends of the transfer box 3 is refined.

[0033] Inside the baffle 315 at each end of the box body 311, there is a rectangular sealing plate 314 that can slide up and down, used to open and close the opening 318.

[0034] A groove 317 is provided at the bottom of the box body 311. A connecting frame 316 that can slide up and down is provided in the groove 317. The end of the connecting frame 316 is fixedly connected to the bottom of the sealing plate 314. The sliding of the connecting frame 316 is controlled by the top ring 213 of the conveyor 2.

[0035] When the empty transfer box 3 is lifted off the conveyor 2, the connecting frame 316 and the sealing plate 314 are in a low position under the action of gravity. The sealing plate 314 does not block the opening 318, which is convenient for loading. When the full transfer box 3 is lifted onto the conveyor 2, as the box body 311 falls, the groove 317 at its bottom will align with and accommodate the top ring 213 on the conveyor roller 212. The top ring 213 rises in the groove 317, pushing the connecting frame 316 to move upward, thereby driving the sealing plate 314 to slide upward until the opening 318 is completely closed. No additional steps are required. When the heat treatment is completed and the transfer box 3 is lifted off the conveyor 2, the top ring 213 disengages from the groove 317, and the sealing plate 314 automatically slides down under the action of gravity to open the opening 318, which is convenient for unloading.

[0036] During long-term operation, this equipment requires regular application of high-temperature grease to all rotating and sliding parts, regular cleaning of oxide debris and dust inside the transfer box, and regular inspection of the integrity of the insulation layer inside the cavity. Any damage should be replaced promptly to ensure long-term stable operation of the equipment.

[0037] However, as is well known to those skilled in the art, the working principles and wiring methods of the heat treatment furnace 1 and the conveyor 2 are conventional methods or common knowledge, and will not be described in detail here. Those skilled in the art can make any selections according to their needs or convenience.

[0038] The accompanying drawings in this application are for illustrative purposes only. The dimensions and shapes of the components shown are not actual limitations but are merely schematic representations. In actual implementation, the components can be reasonably configured and adjusted according to specific needs and actual conditions.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A seamless stainless steel tube with ultra-thin walls for aerospace applications, characterized in that, include: The pipe body is a one-piece molded stainless acid-resistant steel pipe with a long, straight, seamless tubular structure and an extremely thin-walled structure.

2. A multi-stage heat treatment preparation apparatus for preparing the aerospace-grade ultra-thin-walled stainless steel seamless tube as described in claim 1, characterized in that, include: Multiple heat treatment furnaces (1) are arranged in sequence. Each heat treatment furnace (1) includes a furnace body (111) and an upper chamber (112) and a lower chamber (114) located on the upper and lower layers of the furnace body (111), respectively. The conveyor (2) is arranged along the direction of multiple furnace bodies (111). The conveyor (2) includes a frame (211) and multiple rotating conveyor rollers (212) that are equidistantly distributed along the length of the frame (211). The transfer box (3) is used to load the seamless tube body. The transfer box (3) includes a box body (311) and an openable and closable channel on the surface of the box body (311). The openable and closable channel includes two upper ventilation channels (320) respectively opened on the top two sides of the box body (311) and two side ventilation channels (321) respectively opened on the side walls of the box body (311). An openable and closable upper partition (313) is provided in the upper ventilation channel (320), and an openable and closable side partition (323) is provided in the side ventilation channel (321). The transfer box (3) also includes a guide structure for controlling the opening and closing of the upper partition (313) and the side partition (323).

3. The multi-stage heat treatment preparation equipment according to claim 2, characterized in that, Both ends of the furnace body (111) are provided with passage openings (113) for making the upper chamber (112) and the lower chamber (114) open structures; Both ends of the box body (311) are fixedly provided with baffles (315), and the surface of the baffles (315) is provided with an opening (318) that communicates with the cavity of the box body (311).

4. The multi-stage heat treatment preparation equipment according to claim 3, characterized in that, The upper partition (313) is fixedly provided with a rotating shaft (319) along the length direction, and the rotating shaft (319) is located at a non-central position along the width direction of the upper partition (313). Both ends of the rotating shaft (319) are rotatably arranged with the inner wall of the upper ventilation duct (320). The side partition (323) is slidably installed up and down along the height direction of the side ventilation duct (321).

5. The multi-stage heat treatment preparation equipment according to claim 4, characterized in that, The outer sides of one end of the box body (311) are provided with cavities (325). The guide structure includes a connecting ring seat I (326) and a connecting ring seat II (329) disposed inside the cavity (325), and also includes a guide block (4) disposed inside the frame (211 and cooperating with the connecting ring seat II (329). One end of the rotating shaft (319) extends to the upper part of the cavity (325) on the same side. The connecting ring seat I (326) is fixedly sleeved on the outer wall of the rotating shaft (319). The outer wall of the connecting ring seat I (326) is provided with a protruding end I (3261). The connecting ring seat II (329) is rotatably disposed inside the cavity (325). Below, the outer wall of the connecting ring seat II (329) is provided with protruding protrusions II (3291) and III (3292), respectively. The side walls of the protrusions I (3261) and II (3291) are fixedly provided with connecting shafts (327). The outer walls of the two connecting shafts (327) are rotatably sleeved with the same connecting arm (328). The guide block (4) is fixedly provided on the side wall of the frame (211). The bottom wall of the cavity (325) is provided with a through-hole (3251) that communicates with the outside. The protrusion III (3292) extends to the outside through the through-hole (3251) and cooperates with the guide surfaces (411) on both sides of the side wall of the guide block (4).

6. The multi-stage heat treatment preparation equipment according to claim 5, characterized in that, The guide structure also includes an inclined push seat (324) disposed on the side wall of the side partition (323) and a top seat (5) disposed in the frame (211). The inclined push seat (324) is fixedly disposed on the side wall of the side partition (323) and is inclined. The top seat (5) is fixedly disposed on the side wall of the frame (211), and the top of the top seat (5) is provided with an inclined push surface (511) for cooperating with the inclined push seat (324).

7. The multi-stage heat treatment preparation equipment according to claim 6, characterized in that, The upper ventilation duct (320) has an upper limit plate (3201) and a lower limit plate (3202) fixedly installed on its upper and lower sides, respectively, away from each other. The upper partition (313) has an upper concave surface (3131) and a lower concave surface (3132) respectively at its top and bottom, which cooperate with the upper limit plate (3201) and the lower limit plate (3202) respectively.

8. The multi-stage heat treatment preparation equipment according to claim 7, characterized in that, The side wall of the box body (311) is provided with a relief groove (322) that communicates with the side ventilation channel (321) and cooperates with the inclined push seat (324).

9. The multi-stage heat treatment preparation equipment according to claim 5, characterized in that, The transfer box (3) also includes two lifting and closing sealing plates (314). The sealing plates (314) are slidably disposed on the side of the opening (318) to close it. The bottom of the box body (311) is provided with a groove (317). A connecting frame (316) is slidably disposed inside the groove (317). The end of the connecting frame (316) is fixedly disposed with the sealing plate (314) on the same side. The outer wall of the conveying roller (212) is fixedly fitted with a top ring (213) corresponding to the groove (317).

10. The multi-stage heat treatment preparation equipment according to claim 5, characterized in that, Both sides of the outer wall of the conveying roller (212) are fixedly fitted with limiting rings (214) for limiting the box body (311), and a hanging ring (312) is fixedly installed on the top of the box body (311).

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