A method and apparatus for producing a thick-walled stainless steel seamless pipe with a high yield

Abstract

The application discloses a high yield preparation method and equipment for thick-wall stainless steel seamless pipes, and aims to solve the problems of low yield, low efficiency and poor precision in traditional processes. The method comprises the following steps: high-quality blank preparation (full skin peeling to remove genetic defects), heating and full-range descaling, multi-station rotary plastic deformation perforation, online finishing cutting, heat treatment and finishing; the equipment comprises an integrated platform, a multi-station rotary disc type perforator, a rotary full-range descaler, a roller type conveying line mechanism and the like, the multi-station rotary disc type perforator realizes continuous operation of feeding, perforation and material returning, the rotary full-range descaler completes full-range descaling of round blanks without dead angle, and each structure is linked and adapted to high-temperature working conditions. The application blocks the genetic defects from the source, improves the perforation precision and production efficiency, and systematically improves the comprehensive yield, size precision and production efficiency of the thick-wall stainless steel seamless pipes.

Description

Technical Field

[0001] This invention relates to the field of steel pipe manufacturing technology, specifically to a method and equipment for producing thick-walled stainless steel seamless pipes with high yield. Background Technology

[0002] Thick-walled stainless steel seamless pipes, due to their excellent corrosion resistance, high-temperature strength, and structural stability, are widely used in high-end equipment manufacturing fields such as petrochemicals, nuclear power, high-pressure boilers, and shipbuilding, and are indispensable key basic components in the industrial system. Their core manufacturing process typically follows a technical route of "solid round billet → heating → piercing → rolling / finishing → heat treatment." Yield, dimensional accuracy, and surface quality are the core indicators for evaluating the manufacturing technology level of this type of product, directly determining production costs and market competitiveness.

[0003] Currently, the traditional manufacturing process and equipment for thick-walled stainless steel seamless pipes suffer from numerous technical bottlenecks, the specific defects of which are as follows: Imperfect billet pretreatment process: Traditional processes often use partial grinding or turning to treat the surface of round billets, failing to achieve 100% circumferential peeling. Genetic defects such as cracks, folds, and inclusions on the surface of round billets cannot be completely removed. These defects will be inherited and extended during subsequent hot working processes, resulting in a high scrap rate in piercing and finishing processes, which is the core source of low yield.

[0004] Limited descaling effect: Traditional high-pressure water descaling devices mostly use fixed nozzle structures, which can only rinse one side or a part of the round billet, and cannot achieve 360° all-round descaling. The iron oxide scale on the surface of the high-temperature round billet is not completely removed. The residual oxide scale is pressed into the metal matrix during the piercing process, forming defects such as pits and pinholes on the inner and outer surfaces. This not only reduces the surface quality of the product, but also requires an increase in the subsequent finishing allowance, resulting in material waste.

[0005] The piercing process and equipment are inefficient and produce poor forming quality: Traditional piercing equipment is mostly a single-station structure, with feeding, piercing, and unloading processes carried out independently in separate steps, resulting in slow production cycle and low continuity. At the same time, conventional skew rolling piercing and pressure piercing processes are prone to problems such as wall thickness eccentricity, excessive ellipticity, and tail triangle defects when forming thick-walled tubes. The plastic deformation process lacks precise peripheral constraints, making it difficult to control the uniformity of thick-walled tube forming. Furthermore, the mandrel is prone to bending and breaking due to uneven stress, and it cannot stably adapt to the high-temperature plastic deformation characteristics of thick-walled stainless steel.

[0006] Outdated online quality control and fixed-length cutting technologies: Traditional processes mostly use offline dimensional inspection and defect detection, which cannot obtain real-time tube quality data. Fixed-length cutting is mostly performed according to a fixed length, and it is impossible to dynamically plan the cutting scheme according to the irregular areas at the beginning and end of the tube and the location of internal minor defects. The removal of defective sections is unreasonable and the effective tube material utilization rate is low, which further reduces the overall yield.

[0007] The aforementioned technical defects result in a yield rate of only 70%-75% for traditional thick-walled stainless steel seamless pipes, and the product dimensional accuracy and surface quality fluctuate greatly, failing to meet the high-quality and low-cost manufacturing requirements of high-end fields for thick-walled stainless steel seamless pipes.

[0008] Therefore, developing a high-yield, continuous, and high-precision method for preparing thick-walled stainless steel seamless pipes, along with supporting equipment, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0009] The purpose of this invention is to provide a method and equipment for preparing thick-walled stainless steel seamless pipes with high yield, so as to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following process steps: including high-quality billet preparation, heating and surface treatment, rotary plastic deformation piercing, online finishing and cutting, heat treatment and finishing; Step 1: Preparation of high-quality billets: Stainless steel round billets are produced by continuous casting or forging; Full peeling process: At room temperature, the round billet is subjected to 100% circumferential surface peeling through grinding or cutting to completely remove all genetic defects such as surface cracks and impurities, and obtain high-quality billet with accurate dimensions and smooth surface. Cut to length: According to the production plan, the peeled high-quality long blanks are cut into the required lengths using a sawing machine. Step 2: Heating and Surface Treatment Uniform heating: The high-quality, fixed-length round billet is fed into a walking beam or ring furnace and heated to a uniform plastic deformation temperature of 1150-1250℃. High-pressure water curtain descaling: After exiting the furnace, the high-quality, high-temperature round billet is sent to a rotary all-around descaling device via a roller conveyor system to thoroughly remove the iron oxide scale generated during the heating process, creating good interface conditions for subsequent piercing. Step 3: Rotational plastic deformation perforation: Feeding and positioning: The high-temperature round billet, after being descaled by the rotary all-round descaling device, is fed into the multi-station rotary perforator through another roller conveyor mechanism. The high-temperature cleaned round billet is located at the perforation station of the multi-station rotary perforator. Station adjustment and alignment: The multi-station rotary piercing machine operates to adjust the high-temperature cleaned round billet to the station aligned with the piercing head, while providing loading space and foundation for the high-temperature round billet that has been descaled by the rotary all-round descaling machine. The rotating plastic deformation piercing head forms a continuous inner hole in the metal at the center of the inner round blank of the multi-station rotary piercing machine through plastic deformation. Separation and unloading: The multi-station rotary punch continues to run. The punched round billet moves to the unloading station, and then the formed thick-walled tube is smoothly pushed out of the chamber and falls onto the output roller table. Step 4: Online refining and cutting: Online Dimension and Defect Inspection: The tube enters the online monitoring station, where the outer diameter and ovality are measured by a laser scanner, and the wall thickness and internal defects are quickly scanned by a high-temperature ultrasonic flaw detector; Length planning and cutting: The detection data is transmitted to the central control system in real time. The system dynamically calculates and generates the optimal length cutting plan based on the size requirements and the location of the geometric irregular areas or minor defects at the beginning and end of the detection, so as to maximize the material utilization rate. Finally, the flying saw or hot saw performs precise cutting. Step 5: Heat treatment and finishing: Solution treatment: For austenitic stainless steel, solution treatment is carried out in a protective atmosphere bright annealing furnace to obtain a uniform structure and optimal corrosion resistance. Straightening, flattening, and non-destructive testing: We perform routine straightening, flattening, and chamfering, as well as comprehensive ultrasonic, eddy current, and other non-destructive testing and hydrostatic testing to ensure the quality of the finished pipes.

[0011] Preferably, the rotary all-around descaling device drives the high-temperature round billet to rotate, and through the dense water curtain formed by its own spray, it thoroughly removes the iron oxide scale generated during the heating process by means of thermal shock and mechanical impact, exposing a clean metal surface.

[0012] Preferably, the high-speed rotating piercing head moves towards the multi-station rotary piercing machine, penetrating deep into the round blank cavity of the multi-station rotary piercing machine, and advances axially towards the high-temperature cleaned round blank at a constant speed. Under the combined action of rotation and axial feed, the piercing head forms a continuous inner hole in the metal at the center of the round blank through plastic deformation. The multi-station rotary piercing machine cycles sequentially to realize continuous operation of the feeding, piercing, and unloading stations, ensuring the rhythm of production.

[0013] A thick-walled stainless steel seamless pipe manufacturing equipment, characterized in that it includes an integrated platform, a multi-station rotary perforator, a rotary all-around descaling device, a roller conveyor mechanism, roller plates, roller sets, support legs, hydraulic cylinder seats, propulsion hydraulic cylinders, a propulsion integrated seat, a high-speed perforation shaft, a perforation driver, and a perforation head. The integrated platform is fixedly installed above the support legs and located on one side of the multi-station rotary perforator. The roller conveyor mechanism is installed between the multi-station rotary perforator and the rotary all-around descaling device. Two symmetrical roller conveyors are installed on one side of the platform, and a roller assembly is rotatably installed between the two roller conveyors. The roller assembly is connected to the output end of a synchronous driver installed on one of the roller conveyors. The hydraulic cylinder seat is fixed to the integrated platform by bolts and welding. The output end of the propulsion hydraulic cylinder installed on the hydraulic cylinder seat is connected to a propulsion integrated seat that is slidably installed on the integrated platform. The output end of the perforation driver installed on the propulsion integrated seat is connected to one end of a high-speed perforation shaft. The other end of the high-speed perforation shaft is equipped with a perforation head.

[0014] Preferably, the multi-station rotary perforator includes a disc cover, an anchor base, a perforation port, a discharge port, a feed port, a push port, a multi-station disc, a central shaft, thrust bearings, round billet cavity stations, gear teeth, a drive gear, a drive shaft, and a worm gear motor. The disc cover is fixed to the ground by the anchor base installed below. One side of the disc cover has the perforation port and the discharge port through it, and the other side has the feed port and the push port through it. The multi-station disc is rotatably mounted inside the disc cover by two thrust bearings and is rotatably connected to the central shaft fixedly installed inside the disc cover. The multi-station disc itself has numerous round billet cavity stations through it. The gear teeth in the middle of its outer surface mesh with the drive gear installed on the drive shaft. The drive shaft is rotatably mounted inside the disc cover, and one end of it is connected to the output end of the worm gear motor installed outside the disc cover.

[0015] Preferably, the piercing port and the ejector port are located on the surface of the wheel cover near the piercing head and the roller assembly, with the piercing port overlapping the axis of the piercing head. The feed port and the push port are located on the surface of the wheel cover opposite to the piercing port and the ejector port, with the push port and the ejector port corresponding to each other and on the same horizontal line. The piercing port, the ejector port, the feed port, and the push port all correspond to the round billet cavity positions of the multi-station wheel. The push port and the ejector port correspond to the same round billet cavity position. The round billet that has been pierced inside the round billet cavity position can exit from the ejector port and smoothly transition onto the roller assembly. The piercing head can perform plastic deformation piercing on the round billet inside the round billet cavity position through the piercing port.

[0016] Preferably, a pusher support frame is fixedly installed on the surface of the outer cover of the wheel with a pusher opening. The output end of the ejector hydraulic cylinder fixedly installed on the pusher support frame is connected to the ejector disc. The ejector hydraulic cylinder can drive the ejector disc to move towards the pusher opening and push the round blank with holes completed inside the round blank cavity station towards the ejector opening. The round blank cavity station can limit the outer diameter of the round blank. The multi-station wheel can be driven by a drive gear and rotate around the center point of the central axis.

[0017] Preferably, the rotary omnidirectional descaling device includes a descaling box, a high-pressure water tank, high-pressure nozzles, an inspection door, a sludge collection box, drive rollers, and a high-temperature resistant servo motor. The high-pressure water tank, fixedly installed on the side of the descaling box, is connected to several high-pressure nozzles via a high-pressure pump and pipelines. The high-pressure nozzles are installed inside the upper part of the descaling box and above the sludge collection box. The inspection door is hinged to the surface of the descaling box. Two drive rollers are rotatably installed inside the descaling box, and one end of one of the drive rollers is connected to the output end of a high-temperature resistant servo motor fixedly installed outside the descaling box.

[0018] Preferably, several high-pressure nozzles are arranged in an arc-shaped path above the interior of the descaling box, and above the circular billet channel, drive rollers, and sludge collection box that are opened through the descaling box. Two oppositely arranged drive rollers are located on the lower sides of the circular billet channel, and can roll in contact with the lower side surfaces of the circular billet. The high-temperature servo motor can drive the circular billet to rotate by driving a single drive roller. The high-pressure nozzles generate high-pressure water jets that can act on the outer surface of the high-temperature circular billet below. The oxide scale and wastewater of the high-temperature circular billet can fall downwards and be collected by the sludge collection box.

[0019] Preferably, the round billet processed by the rotary all-around descaling device can be smoothly conveyed to the multi-station rotary perforator through the roller conveyor mechanism, and enter one of the round billet cavity stations through the feed port. The roller conveyor mechanism includes a conveyor support, conveyor side plates, conveyor wheels and a synchronous drive transmission box. Two symmetrical conveyor side plates are fixedly installed on the top of the conveyor support. Several conveyor wheels are rotatably installed between the two conveyor side plates. The same end of the several conveyor wheels is connected to the output end of one of the synchronous drive transmission boxes. The input end of the synchronous drive transmission box is connected to the output end of a motor installed on its own outer shell.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs a 100% circumferential peeling process at room temperature to thoroughly remove genetic defects such as cracks and impurities from the surface of the billet, thereby obtaining high-quality billets with precise dimensions and smooth surfaces. This process blocks the genetic propagation path of defects from the source, significantly reducing the scrap rate in subsequent piercing and finishing processes, and laying the foundation for high yield.

[0021] 2. This invention uses a rotary all-around descaling device to drive the high-temperature round billet to rotate, and in conjunction with the arc-shaped high-pressure nozzles, forms a dense water curtain on the surface of the round billet at 360°. It uses the combined action of thermal shock and mechanical impact to thoroughly remove iron oxide scale, achieve descaling without dead angles, expose a clean metal surface, avoid oxide scale pressing defects, reduce subsequent finishing allowance, and improve material utilization and product surface quality.

[0022] 3. The multi-station rotary perforator of this invention achieves step-by-step station switching through worm gear drive, integrating feeding, perforation, and unloading stations into one unit. Each process is carried out synchronously and cyclically, breaking the efficiency bottleneck of traditional single-station perforation, increasing the production cycle by more than 30%, and realizing continuous and efficient production of thick-walled steel pipes.

[0023] 4. The present invention combines the rotation of the piercing head with the axial feed, and with the peripheral constraint of the round blank cavity of the multi-station wheel, it realizes uniform plastic deformation of the central metal of the thick-walled round blank, effectively solving the problems of wall thickness eccentricity and excessive ellipticity in the traditional piercing process. The dimensional accuracy of the thick-walled tube is improved to ±0.1mm, and the forming quality is significantly optimized.

[0024] 5. The integrated platform and roller conveyor mechanism of this invention achieve seamless connection of descaling, perforation and conveying units, and compact logistics path; the core components such as multi-station wheel and perforation actuator are designed to adapt to high temperature working conditions, and with the smooth material discharge structure of the material discharge hydraulic cylinder and material discharge disc, the positioning accuracy is reduced due to high temperature thermal deformation, and the failure rate of continuous operation of the equipment is reduced by more than 20%. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the integrated platform of the present invention.

[0027] Figure 3 This is a schematic diagram of the multi-station rotary perforator structure of the present invention.

[0028] Figure 4 For the present invention Figure 3 Another structural diagram from another perspective.

[0029] Figure 5 This is a partial cross-sectional structural diagram of the multi-station rotary perforator of the present invention.

[0030] Figure 6 For the present invention Figure 5 A magnified schematic diagram of the structure at point A.

[0031] Figure 7 This is a schematic diagram of the rotary all-around descaling device of the present invention.

[0032] Figure 8 This is a schematic diagram of the roller conveyor mechanism of the present invention.

[0033] In the picture: Integrated platform 1, multi-station rotary perforator 2, disc cover 21, anchor base 22, perforation port 23, unloading port 24, feed port 25, push port 26, multi-station rotary disc 27, central shaft 28, thrust bearing 29, billet cavity station 210, gear teeth 211, drive gear 212, drive shaft 213, worm gear motor 214, push support frame 215, unloading hydraulic cylinder 216, unloading disc 217, rotary all-around descaling 3. Descaling box 31. High-pressure water tank 32. High-pressure nozzle 33. Inspection door 34. Sludge collection box 35. Drive roller 36. High-temperature servo motor 37. Roller conveyor mechanism 4. Conveying support 41. Conveying side plate 42. Conveying wheel 43. Synchronous drive transmission box 44. Roller plate 5. Roller assembly 6. Support leg 7. Hydraulic cylinder seat 8. Propulsion hydraulic cylinder 9. Propulsion integrated seat 10. High-speed piercing shaft 11. Piercing driver 12. Piercing head 13. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of the invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., which indicate at least the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating at least or implying relative importance. In the description of the invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The present invention will be further described in detail below with reference to specific embodiments. This embodiment is applicable to the preparation of austenitic thick-walled stainless steel seamless pipes (such as 304, 316L, and 321 models) with a wall thickness of 10-100mm and an outer diameter of 50-650mm. When used with the thick-walled stainless steel seamless pipe preparation equipment described in the present invention, it can effectively improve the yield and balance production efficiency and product quality.

[0037] This invention discloses a method for preparing thick-walled stainless steel seamless pipes with high yield, specifically including the following process steps: Step 1: Preparation of high-quality billets: 1) Billet selection: Stainless steel round billets are selected by continuous casting or forging. The outer diameter of the billet is determined according to the specifications of the finished pipe, with a machining allowance of 20-50mm. Forged round billets are preferably forged by hydraulic press, which can further refine the grains and reduce internal porosity, inclusions and other defects. Continuously cast round billets need to be pre-polished to remove protruding defects such as gates and burrs generated during the continuous casting process.

[0038] 2) Full Peeling Process: Under normal temperature conditions (20-30℃), a CNC cylindrical grinder or precision lathe is used to perform 100% circumferential peeling on the round blank. The peeling thickness is controlled between 0.5-2mm, with the specific thickness adjusted according to the degree of surface defects on the round blank—the upper limit thickness is used for round blanks with more severe surface defects, and the lower limit thickness is used for round blanks with minor defects. During the processing, the feed speed of the lathe or grinder is controlled at 0.1-0.3mm / r, and the rotation speed is 50-150r / min to ensure that the surface finish of the round blank after processing is ≤1.6μm, with accurate dimensions and no inherited defects such as cracks, scratches, inclusions, or folds. The outer diameter tolerance of the round blank is controlled within ±0.1mm.

[0039] 3) Fixed-length sawing: Based on the length requirements of the finished pipe and the subsequent processing allowance, the high-quality long blanks after peeling are sawed to a fixed length using a CNC band saw, with a sawing length of 1-6m. During the sawing process, cooling spray is used to cool the saw blade and the cut edge of the round blank to prevent oxidation or micro-cracks caused by high temperature. After sawing, the cut edge is ground and chamfered at a chamfer angle of 45° and a chamfer length of 2-5mm to prevent damage to the cut edge during subsequent conveying and heating.

[0040] Step 2: Heating and Surface Treatment 1) Uniform Heating: High-quality, fixed-length round billets are fed into a walking beam furnace (or a ring furnace; for mass production, a walking beam furnace is preferred for precise temperature control). The billets are heated in stages to a uniform plastic deformation temperature of 1150-1250℃, suitable for the hot working characteristics of austenitic stainless steel. After reaching the target temperature, the billets are held for 1-2 hours to ensure uniform internal temperature, sufficient austenitization, and optimal plasticity. During the holding period, the furnace atmosphere is controlled to be neutral (a mixture of nitrogen and argon, volume ratio 3:1) to reduce surface oxidation of the billets.

[0041] 2) High-pressure water curtain descaling: After exiting the furnace, the high-quality, high-temperature round billet (temperature maintained at 1100-1200℃) is smoothly conveyed to the rotary all-around descaling device via a roller conveyor mechanism. The conveying speed is matched with the processing speed of the descaling device. After the rotary all-around descaling device is started, its two internal drive rollers rotate synchronously under the drive of a high-temperature servo motor, driving the high-temperature round billet to rotate around its own axis at a speed of 10-30 r / min. At the same time, the high-pressure water in the high-pressure water tank is pressurized to 15-30 MPa by a high-pressure pump and sprayed into a dense water curtain through several arc-shaped high-pressure nozzles, which evenly covers the outer circumference of the round billet. Utilizing the thermal shock of a high-temperature round billet with cold water (a temperature difference exceeding 1000℃, causing the iron oxide scale to peel off instantly due to thermal expansion and contraction), combined with the mechanical impact of a high-pressure water jet, the iron oxide scale generated during the heating process (including primary and secondary oxide scale) is thoroughly removed. This exposes a clean metal surface, creating favorable interface conditions for subsequent rotational plastic deformation piercing and preventing oxide scale from being pressed into the capillary tube or forming pits and other defects on the outer surface. The descaled iron oxide scale falls into a collection tank along with the wastewater for centralized treatment, preventing pollution of the production environment.

[0042] Step 3: Rotational plastic deformation perforation: 1) Feeding and Positioning: After being descaled by a rotary all-around descaling device, the high-temperature clean surface round billet is smoothly conveyed to the multi-station rotary piercing mill via another roller conveyor mechanism. During the conveying process, heat-insulating baffles are used to reduce the temperature loss of the billet (ensuring that the billet temperature is not lower than 1050℃ to avoid decreased plasticity and difficulty in piercing). After being conveyed to the correct position, the high-temperature clean surface round billet enters the piercing station (billet cavity station) of the multi-station rotary piercing mill. The inner diameter of the billet cavity station is 0.1-0.2mm larger than the outer diameter of the billet, which can initially limit the billet and prevent it from shifting during subsequent piercing.

[0043] 2) Station Adjustment and Alignment: Start the worm gear motor of the multi-station rotary piercing machine. The worm gear motor drives the drive shaft and drive gear to rotate. The drive gear meshes with the gear teeth on the outer surface of the multi-station rotary disc, causing the multi-station rotary disc to rotate smoothly around the central axis. This adjusts the piercing station containing the high-temperature clean surface round blank to the piercing station aligned with the piercing mandrel. At the same time, the empty piercing station rotates to the feeding position, providing space and foundation for the subsequent descaling of the high-temperature round blank, thus achieving synchronous connection between the feeding and piercing processes.

[0044] 3) Rotary Plastic Deformation Piercing: The piercing actuator and the propulsion hydraulic cylinder are activated. The piercing actuator drives the high-speed piercing shaft and piercing mandrel to rotate at high speed (the piercing mandrel speed is 50-200 r / min, made of molybdenum-based high-temperature alloy, resistant to high temperatures and wear, suitable for high-temperature plastic deformation conditions). Simultaneously, the propulsion hydraulic cylinder pushes the propulsion integrated seat to slide smoothly along the guide rail on the integrated platform, driving the high-speed piercing shaft and piercing mandrel towards the multi-station rotary piercing machine, penetrating deep into the round billet cavity of the piercing station, and axially advancing towards the high-temperature clean surface round billet at a constant speed (0.3-1.0 m / min). Under the combined action of the rotation and axial feed of the piercing mandrel, the metal at the center of the round billet is compressed and plastically deformed, gradually forming a continuous inner hole. The round billet cavity station provides limiting constraints on the outer periphery of the round billet, preventing the round billet from shifting, having eccentric wall thickness, or exceeding the ellipticity standard during the piercing process. During the piercing process, the piercing pressure is controlled at 2000-5000t, and adjusted according to the material and wall thickness of the billet to ensure uniform plastic deformation and avoid defects such as cracks and uneven wall thickness. At the same time, inert gas (argon) is used to cool and protect the contact area between the piercing mandrel and the billet, reducing the wear of the piercing mandrel and extending its service life.

[0045] 4) Separation and Unloading: After piercing, a thick-walled tube is formed (the tube wall thickness is 5-15mm thicker than the finished tube wall thickness, allowing for machining allowance). The multi-station rotary piercing machine continues to rotate step by step, adjusting the piercing station containing the thick-walled tube to the unloading station. Simultaneously, the next station containing the round blank is adjusted to the piercing station, and the piercing operation is started, achieving continuous cycle. When the station containing the thick-walled tube reaches the unloading station, the unloading hydraulic cylinder on the pusher support is activated. The unloading hydraulic cylinder drives the unloading disc to move towards the pusher port. The unloading disc makes flexible contact with the end face of the thick-walled tube (avoiding scratching the tube surface), smoothly pushing the thick-walled tube from the round blank cavity station towards the unloading port. The thick-walled tube falls onto the output roller conveyor (roller set) through the unloading port. The rotation speed of the output roller conveyor matches the unloading speed, smoothly conveying it to the next process.

[0046] 5) Continuous operation: The multi-station rotary puncher cycles sequentially to continuously complete the continuous operation of feeding at the punching station, punching at the punching station, and unloading at the unloading station. This effectively shortens the process interval, ensures the rhythm of production, and greatly improves production efficiency. Compared with traditional single-station punching equipment, the production efficiency is increased by more than 30%.

[0047] Step 4: Online refining and cutting: 1) Online Dimension and Defect Inspection: Thick-walled tubes are conveyed to the online monitoring station via output rollers. The online monitoring station integrates a laser scanner and a high-temperature ultrasonic flaw detector to achieve simultaneous and rapid inspection of tube dimensions and internal defects. The laser scanner is installed above and on both sides of the tube to scan the outer diameter and ellipticity in real time. The high-temperature ultrasonic flaw detector uses a 2-5MHz probe to scan along the axial and circumferential directions of the tube, detecting the wall thickness and internal defects (such as cracks, porosity, inclusions, etc.). The inspection data is transmitted to the central control system (PLC control system) in real time. The system analyzes and stores the data in real time, marking the location and range of geometrically irregular areas at the beginning and end of the tube and the location of internal minor defects.

[0048] 2) Length Planning and Cutting: Based on the finished pipe's dimensional requirements (outer diameter, wall thickness, length), and combined with the detected geometric irregularities at the pipe's ends and the location and extent of internal minor defects, the central control system dynamically calculates and generates the optimal length cutting plan. This prioritizes avoiding defective areas, maximizing the use of qualified pipe material, and reducing material waste. After length planning is completed, the central control system sends a cutting command to the flying saw (or hot saw, selected based on the pipe temperature; hot saw is used when the pipe temperature is above 800℃, and flying saw is used when it is below 800℃). The flying saw (or hot saw) precisely cuts the pipe at a cutting speed of 0.5-1.5 m / min, avoiding skewed cuts that would increase subsequent finishing allowances. After cutting, defective sections are collected and processed separately, while qualified pipes are transported to the heat treatment process.

[0049] Step 5: Heat treatment and finishing: 1) Solution treatment: For austenitic stainless steel capillary tubes, they are sent into a protective atmosphere bright annealing furnace for solution treatment. The solution temperature is controlled at 1050 - 1150 °C, and the holding time is determined according to the wall thickness of the capillary tube, which is 1 - 3 min / mm (that is, for every 1 mm increase in the wall thickness of the capillary tube, the holding time increases by 1 - 3 min), ensuring that the internal structure of the capillary tube is fully austenitized and eliminating the internal stress generated during the plastic deformation process. During the solution treatment process, an inert protective atmosphere (argon gas) is introduced into the furnace to prevent the surface of the capillary tube from oxidizing and discoloring, and to maintain the surface finish. After the holding is completed, rapid cooling is carried out by water cooling, and the cooling rate ≥ 20 °C / s to inhibit the precipitation of carbides, obtain a uniform austenite structure, improve the corrosion resistance, toughness and strength of the finished tube, and ensure that the intergranular corrosion resistance of the finished tube meets the requirements of GB / T4334 - 2022 standard.

[0050] 2) Straightening, end facing, and non-destructive testing: The capillary tube after solution treatment is sent into a hydraulic straightening machine for conventional straightening. The straightening pressure is adjusted to 500 - 2000 t according to the wall thickness of the capillary tube. The straightness of the straightened capillary tube ≤ 0.2 mm / m to avoid the bending of the capillary tube affecting subsequent use. After straightening, the two ends of the capillary tube are end faced and chamfered by an end facing and chamfering machine to ensure that the two end faces are flat and free of burrs. The chamfering angle is 45°, and the chamfering length is 2 - 5 mm to adapt to the subsequent pipeline connection requirements. Finally, a comprehensive non-destructive testing is carried out on the finished tube after end facing and chamfering, including ultrasonic flaw detection (detecting internal defects), eddy current flaw detection (detecting surface and near-surface defects), and at the same time, a hydrostatic test is carried out (the test pressure is 1.5 - 2.0 times the working pressure of the finished tube, and the pressure holding time is 30 - 60 min. It is qualified if there is no leakage and no deformation), ensuring that the finished tube has no defects, and the dimensional accuracy, surface quality and mechanical properties all meet the design requirements, and finally obtaining qualified thick-walled stainless steel seamless tubes.

[0051] In this embodiment, through the above-mentioned full-process process optimization, combined with the supporting preparation equipment, the problems of many defects, low成材率 (成材率 should be translated as "yield rate" in English), and low production efficiency in the traditional preparation process are effectively solved. The yield rate of the finished tube is increased to 85 - 92%, the dimensional accuracy is controlled within ±0.1 mm, and the surface finish ≤ 0.8 μm, which can be widely used in high-end fields such as petrochemical industry, nuclear power energy, and high-pressure boilers.

[0052] The following further details the preparation equipment of the thick-walled stainless steel seamless tube described in the present invention with specific embodiments. This equipment is adapted to the high-yield preparation method of the thick-walled stainless steel seamless tube described above, and can realize the integrated continuous operation of processes such as billet pretreatment, descaling, piercing, and conveying. It is adapted to the processing of austenitic stainless steel round billets with a wall thickness of 10 - 100 mm and an outer diameter of 50 - 650 mm, taking into account both the structural stability and the adaptability to high-temperature working conditions.

[0053] As shown in the appendix Figure 1-8 shown: This invention discloses a thick-walled stainless steel seamless pipe manufacturing equipment, characterized in that it comprises an integrated platform 1, a multi-station rotary perforator 2, a rotary all-around descaling device 3, a roller conveyor mechanism 4, a roller plate 5, a roller assembly 6, a support leg 7, a hydraulic cylinder seat 8, a propulsion hydraulic cylinder 9, a propulsion integrated seat 10, a high-speed perforation shaft 11, a perforation driver 12, and a perforation head 13. The integrated platform 1 is fixedly installed above the support leg 7 and located on one side of the multi-station rotary perforator 2. The roller conveyor mechanism 4 is installed between the multi-station rotary perforator 2 and the rotary all-around descaling device 3. Two symmetrical roller conveyor plates 5 are installed on one side above the platform 1. A roller assembly 6 is rotatably installed between the two roller conveyor plates 5. The roller assembly 6 is connected to the output end of a synchronous driver installed on one of the roller conveyor plates 5. The hydraulic cylinder seat 8 is fixed to the integrated platform 1 by bolts and welding. The output end of the propulsion hydraulic cylinder 9 installed on the hydraulic cylinder seat 8 is connected to a propulsion integrated seat 10 slidably installed on the integrated platform 1. The output end of the perforation driver 12 installed on the propulsion integrated seat 10 is connected to one end of a high-speed perforation shaft 11. The other end of the high-speed perforation shaft 11 is equipped with a perforation head 13.

[0054] Furthermore, the multi-station rotary perforator 2 includes a disc cover 21, anchor seats 22, a perforation port 23, a discharge port 24, a feed port 25, a push port 26, a multi-station disc 27, a central shaft 28, a thrust bearing 29, a round blank cavity station 210, gear teeth 211, a drive gear 212, a drive shaft 213, and a worm gear motor 214. The disc cover 21 is made of Q355B carbon steel, welded together, with a wall thickness of 15-20mm. It protects the internal rotating parts and isolates them from high-temperature radiation. Four anchor seats 22 are symmetrically welded below it. The anchor seats 22 are made of cast steel and have waist-shaped mounting holes at the bottom. They are fixed to the concrete foundation using expansion bolts, ensuring the overall stable operation of the multi-station rotary perforator 2 and preventing shaking during high-temperature operation. The outer cover 21 of the wheel has a through-hole 23 and a discharge port 24 on one side near the integrated platform 1, and a feed port 25 and a push port 26 on the other side. All ports are chamfered to avoid scratching the round billet or tube. The multi-station wheel 27 is made of high-temperature alloy casting, and its diameter is designed to be 1.5-3m according to the specifications of the round billet. It is rotatably mounted inside the outer cover 21 by two symmetrically arranged thrust bearings 29. The thrust bearings 29 are high-temperature cylindrical roller thrust bearings, which are suitable for high-temperature conditions below 1200℃ and can withstand the axial thrust generated during piercing. The central shaft 28 is made of 40Cr alloy and is bolted to the center position inside the outer cover 21 by flanges at both ends. The multi-station wheel 27 is sleeved on the outside of the central shaft 28 and is interference-fitted with the inner ring of the thrust bearing 29 to achieve smooth rotation around the central shaft 28. The multi-station wheel 27 has 6-12 circular blank cavity stations 210 evenly distributed along the circumference. The inner diameter of the circular blank cavity station 210 is 0.1-0.2mm larger than the outer diameter of the circular blank to be processed, which is used to limit the circular blank and prevent it from shifting during piercing. The multi-station wheel 27 has an integrally formed gear tooth 211 in the middle of its outer surface. The gear tooth 211 is carburized and quenched to a hardness of HRC55-60. It meshes with the drive gear 212 keyed to the drive shaft 213. The drive shaft 213 is made of 40Cr material and is rotatably mounted in the bearing seat of the wheel cover 21 through high temperature resistant deep groove ball bearings at both ends. One end extends to the outside of the wheel cover 21 and is fixedly connected to the output end of the worm gear motor 214 through a coupling. The worm gear motor 214 is a servo type with a power of 15-30kW. It is fixed to the outer wall of the wheel cover 21 by bolts on the motor base and has a self-locking function, which can ensure that the multi-station wheel 27 does not deviate when it stays at the designated station, and the positioning accuracy reaches ±0.05mm.

[0055] Furthermore, the piercing opening 23 and the unloading opening 24 are symmetrically arranged on the surface of the wheel cover 21 near the piercing head 13 and the roller assembly 6. The distance between them is set according to the number of stations of the multi-station wheel 27, ensuring that the corresponding two round blank cavity stations 210 can be aligned with the piercing head 13 and the roller assembly 6 respectively. The diameter of the piercing opening 23 is 5-10mm larger than the diameter of the piercing head 13, and its axis is completely coincident with the axis of the piercing head 13, with a coaxiality error ≤0.03mm. This ensures that the piercing head 13 can smoothly pass through the piercing opening 23 and enter the round blank cavity station 210 to complete the piercing operation, avoiding offset that would cause piercing deviation. The feed inlet 25 and the pusher inlet 26 are symmetrically opened on the other side surface of the wheel cover 21, forming an angle of 90° or 120° with the perforation port 23 and the ejector port 24 (adjusted according to the number of stations). The diameter of the feed inlet 25 is 1-2 mm larger than the outer diameter of the round billet, which facilitates the round billet to smoothly enter the round billet cavity station 210 through the roller conveyor mechanism 4. The pusher inlet 26 and the ejector port 24 are corresponding and on the same horizontal line, and their axes coincide. The diameter of the pusher inlet 26 is the same as that of the ejector port 24, both of which are 1-2 mm larger than the outer diameter of the tube, ensuring that the ejector plate 217 can push the tube out of the ejector port 24 through the pusher inlet 26. The piercing port 23, the ejector port 24, the feed port 25, and the pusher port 26 all correspond to the positions of the round billet cavity positions 210 on the multi-station wheel 27. Among them, the pusher port 26 and the ejector port 24 correspond to the same round billet cavity position 210. When the position rotates to the ejector position, the ejector hydraulic cylinder 216 drives the ejector disc 217 to pass through the pusher port 26 and push the pierced tube inside the round billet cavity position 210 toward the ejector port 24. After the tube exits from the ejector port 24, it can smoothly transition to the roller group 6 below to realize the continuous conveying of the tube. The piercing head 13 can extend into the corresponding round billet cavity position 210 through the piercing port 23 to perform plastic deformation piercing on the round billet in the cavity. The alignment accuracy of each port with the round billet cavity position 210 is ensured by the self-locking function of the worm gear motor 214.

[0056] Furthermore, on the surface of the wheel cover 21 where the push port 26 is opened, a push support frame 215 is installed by welding and bolts for double fixing. The push support frame 215 is made of channel steel and has sufficient rigidity to withstand the thrust generated by the ejector hydraulic cylinder 216 during operation. The ejector hydraulic cylinder 216 is fixedly installed at the center of the push support frame 215 by a flange. The ejector hydraulic cylinder 216 is a high-pressure plunger type hydraulic cylinder with a rated pressure of 20-30MPa. The stroke is adjusted to 500-1500mm according to the depth of the round billet cavity station 210. Its output end is fixed to the ejector plate 217 by a threaded connection. The ejector plate 217 adopts a carbon steel base + heat-resistant rubber surface structure. The rubber surface thickness is 5-10mm, which can avoid surface scratches caused by hard contact with high-temperature tubes. The axis of the ejector hydraulic cylinder 216 coincides with the axes of the push port 26 and the ejector port 24. When the multi-station wheel 27 rotates the pierced tube to the ejector station, the ejector hydraulic cylinder 216 is activated, driving the ejector disc 217 to move at a constant speed towards the push port 26. After the ejector disc 217 extends into the round billet cavity station 210, it flexibly contacts the end face of the tube and continuously applies a thrust to push the tube towards the ejector port 24 until the tube completely exits the round billet cavity station 210 and falls onto the roller group 6. Then the ejector hydraulic cylinder 216 drives the ejector disc 217 to reset, waiting for the next ejector operation. The inner wall of the round blank cavity station 210 is polished, with a surface roughness of ≤0.8μm, which can limit the outer diameter of the round blank and reduce the friction between the tube and the cavity wall. The multi-station wheel 27 can rotate in a stepping motion along the center point of the central axis 28 under the drive of the drive gear 212, rotating by the angle of one station each time, realizing the continuous cycle of the loading, piercing and unloading stations, and ensuring the production cycle.

[0057] Furthermore, the rotary all-around descaling device 3 includes a descaling box 31, a high-pressure water tank 32, high-pressure nozzles 33, an inspection door 34, a sludge collection box 35, a drive roller 36, and a high-temperature resistant servo motor 37. The descaling box 31 is welded from corrosion-resistant stainless steel plate, with an overall rectangular structure and a wall thickness of 8-12mm. The interior is treated with anti-corrosion measures and can withstand high-pressure water impact and high-temperature radiation. A high-pressure water tank 32 is bolted to one side wall of the descaling box 31. The high-pressure water tank 32 is made of stainless steel and has a volume of 0.5-1m³. It can store high-pressure water and provide a stable water supply. The high-pressure water tank 32 is connected to several high-pressure nozzles 33 through a high-pressure pump (rated pressure 15-30MPa) and stainless steel pipes. A pressure regulating valve is installed on the pipes to adjust the water pressure according to the specifications of the round billet. The high-pressure nozzle 33 is made of wear-resistant alloy and is installed on the nozzle bracket inside the descaling box 31. The nozzle bracket is fixed to the inner wall of the descaling box 31 by bolts. Several high-pressure nozzles 33 are arranged along an arc-shaped trajectory to ensure that the sprayed water curtain can cover the entire circumference of the round blank. The sludge collection box 35 is made of carbon steel and is slidably installed at the bottom of the descaling box 31 via guide rails. The pull-out design makes it easy to clean the collected iron oxide scale and sewage. The sludge collection box 35 is located directly below the high-pressure nozzles 33 to ensure that the iron oxide scale and sewage can fall smoothly into the box. The front of the descaling box 31 is hinged to a maintenance door 34. The maintenance door 34 has a double-layer insulation structure, with an outer steel plate and an inner insulation cotton. The door is equipped with a sealing strip and an observation window. The sealing strip ensures that the inside of the descaling box 31 is sealed to prevent high-pressure water from splashing. The observation window is made of high-temperature tempered glass for easy observation of the descaling effect. On the two side walls inside the descaling box 31, two drive rollers 36 are mounted relative to each other via high-temperature bearing seats. The drive rollers 36 are made of heat-resistant alloy material with an anti-slip surface. The distance between them is adjusted according to the outer diameter of the billet to ensure close rolling contact with the two sides below the billet. One end of one of the drive rollers 36 extends to the outside of the descaling box 31 and is connected to the output end of a high-temperature servo motor 37 fixed on the outer wall of the descaling box 31 via a coupling. The high-temperature servo motor 37 has a power of 5-10kW and can work stably in high-temperature environments below 1200℃. It is used to drive the drive roller 36 to rotate.

[0058] Furthermore, several high-pressure nozzles 33 are arranged in a 180° arc path above the interior of the descaling box 31. The number of nozzles is 12-18, and the spray angles of adjacent nozzles overlap by 5-10° to avoid descaling dead zones. The spray direction of the high-pressure nozzles 33 forms a 30-45° angle with the surface of the billet, which can improve the impact effect of the water jet. The two ends of the descaling box 31 are provided with billet channels. The diameter of the billet channel is 1-2mm larger than the outer diameter of the billet to facilitate the entry and exit of the billet. The high-pressure nozzles 33 are located above the billet channel, the drive rollers 36, and the sludge collection box 35. Two oppositely arranged drive rollers 36 are symmetrically arranged on both sides below the billet channel, and their tops are flush with the axis of the billet channel to ensure that the billet can make close rolling contact with the two drive rollers 36 when passing through. During operation, the high-temperature servo motor 37 starts, driving a single drive roller 36 to rotate. Through the friction between the drive roller 36 and the surface of the billet, the billet rotates at a constant speed of 10-30 r / min around its own axis, ensuring that the outer surface of the billet can be covered by a high-pressure water curtain. At the same time, the water in the high-pressure water tank 32 is pressurized by a high-pressure pump and then transported to each high-pressure nozzle 33 through pipelines. The high-pressure nozzle 33 sprays to form a 360° dense water curtain. The high-pressure water jet (pressure 15-30 MPa) acts on the outer surface of the high-temperature billet below. Combined with the thermal shock (temperature difference of more than 1000℃) between the high-temperature billet and the cold water and the mechanical impact of the water jet, the iron oxide scale on the surface of the billet is completely peeled off. The stripped iron oxide scale falls downwards along with the wastewater and is collected by the sludge collection box 35 below. The bottom of the sludge collection box 35 is equipped with a drain outlet, which can periodically discharge wastewater. The iron oxide scale can be centrally treated by pulling out the sludge collection box 35 to avoid polluting the production environment. The synergistic effect of the billet rotation and the high-pressure water curtain can achieve descaling without dead angles, ensuring the surface of the billet is clean and creating good conditions for subsequent rotational plastic deformation piercing.

[0059] Furthermore, the clean, high-temperature round billet after treatment by the rotary all-around descaling device 3 can be smoothly conveyed to the multi-station rotary perforator 2 via the roller conveyor mechanism 4, and enters one of the round billet cavity stations 210 through the feed inlet 25, realizing the continuous connection between the descaling and perforation processes. The roller conveyor mechanism 4 includes a conveyor support 41, conveyor side plates 42, conveyor wheels 43, and a synchronous drive transmission box 44. The conveyor support 41 is welded from channel steel, and its bottom is fixed to the ground with anchor bolts to ensure no shaking during the conveying process. Two symmetrical conveyor side plates 42 are fixedly installed on the top of the conveyor support 41 with bolts. The conveyor side plates 42 are cut from steel plates, and their height is adjusted according to the diameter of the round billet to limit the round billet and prevent the round billet from deviating during the conveying process. Between the two conveyor side plates 42, several conveyor wheels 43 are evenly rotated and installed along the conveying direction. The number of conveyor wheels 43 is set according to the conveying distance (usually 5-10). The conveyor wheels 43 adopt a carbon steel base + wear-resistant rubber surface structure. The rubber surface can increase the friction with the round billet and avoid scratching the surface of the round billet. The spacing of the conveyor wheels 43 is 300-500mm to ensure that the round billet is conveyed smoothly and does not bend. Several conveyor wheels 43 extend from the same end to the outside of one of the conveyor side plates 42, and are connected to a chain via sprockets to form a synchronous transmission structure. This end is connected to the output end of the synchronous drive transmission box 44 via a chain. The synchronous drive transmission box 44 adopts a gear transmission structure and has a speed adjustment function. Its input end is connected to the output end of a motor fixed on its outer casing via a coupling. This motor is a variable frequency motor with a power of 3-5kW, and the conveying speed (0.5-1.0m / min) can be adjusted according to the production cycle to ensure that the conveying speed matches the feeding speed of the multi-station rotary perforator 2 and the descaling speed of the rotary all-round descaler 3. The input end of the roller conveyor mechanism 4 is aligned with the round billet channel of the rotary all-round descaler 3, and the output end is aligned with the feed inlet 25 of the multi-station rotary perforator 2. The conveying height is consistent with the height of the round billet channel and the feed inlet 25 to ensure that the round billet can be smoothly transferred and to avoid collisions or excessive temperature loss during the conveying process.

[0060] First, the preparation equipment and corresponding preparation method of this invention work together. The core is to achieve continuous and high-precision preparation of thick-walled stainless steel seamless pipes through the linkage of various structures. The whole process follows the logical progression of "bill pretreatment - heating and descaling - plastic deformation piercing - finishing and cutting - heat treatment and finishing".

[0061] First, the billet undergoes full peeling on a CNC cylindrical grinder or precision lathe, followed by length sawing on a CNC band saw. It is then fed into a walking beam or ring furnace for heating, completing the high-quality billet preparation and uniform heating process, laying the foundation for subsequent processing. The heated high-temperature billet is then conveyed to a rotary all-around descaling device 3 via a roller conveyor mechanism 4. Once activated, the high-temperature servo motor 37 drives the rotating roller 36 to rotate, causing the billet to rotate around its own axis. Simultaneously, water from the high-pressure water tank 32 is sprayed through high-pressure nozzles 33, thoroughly removing the iron oxide scale from the billet surface through thermal and mechanical impact. Wastewater and iron oxide scale fall into a collection tank 35 for collection. The cleaned billet after descaling continues to be conveyed via the roller conveyor mechanism 4.

[0062] Subsequently, the cleaned round billet enters the piercing station (round billet cavity station 210) of the multi-station rotary piercing mill 2. The worm gear motor 214 drives the drive gear 212 and drive shaft 213 to rotate, causing the multi-station rotary disc 27 to rotate around the central axis 28, adjusting the station containing the round billet to the position aligned with the piercing head 13. At this time, the piercing driver 12 drives the high-speed piercing shaft 11 and the piercing head 13 to rotate, and the propulsion hydraulic cylinder 9 pushes the propulsion integrated seat 10 to slide, causing the piercing head 13 to pass through the piercing opening 23 and extend into the round billet cavity station 210. Through the combined action of rotation and axial feed, the metal in the center of the round billet is plastically deformed to form an inner hole. The round billet cavity station 210 limits the outer periphery of the round billet to ensure piercing accuracy.

[0063] After piercing is completed, the multi-station rotary table 27 continues to rotate, sending the station containing the thick-walled tube to the unloading station. The unloading hydraulic cylinder 216 drives the unloading disc 217 through the push port 26, pushing the tube out from the unloading port 24 and onto the roller group 6. It is then supported by the roller conveyor plate 5 and transported to the next process. The multi-station rotary piercing machine 2 cycles through feeding, piercing, and unloading, and relies on the integrated platform 1 to achieve stable installation and linkage of various piercing-related structures.

[0064] After the tubes are conveyed to the online monitoring station, a laser scanner and a high-temperature ultrasonic flaw detector simultaneously inspect their dimensions and internal defects. The data is transmitted to the central control system, which plans the optimal length setting and controls a flying saw or hot saw to complete the cutting, removing defective sections. Qualified tubes enter a protective atmosphere bright annealing furnace for solution treatment, then are straightened by a hydraulic straightener, and beveled by a flat-end beveling machine. Finally, they undergo ultrasonic flaw detection, eddy current flaw detection, and hydrostatic testing to ensure the finished product is qualified, ultimately yielding thick-walled stainless steel seamless pipes. Throughout the process, the coordinated operation of various structures ensures production continuity and product quality.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing thick-walled stainless steel seamless pipes with high yield, characterized in that: The process includes the following steps: preparation of high-quality billet, heating and surface treatment, rotary plastic deformation piercing, online finishing and cutting, heat treatment and finishing. Preparation of high-quality billets: Stainless steel round billets are produced by continuous casting or forging; Full peeling process: At room temperature, the round billet undergoes 100% circumferential surface peeling to completely remove all genetic defects such as surface cracks and impurities, resulting in a high-quality billet with accurate dimensions and a smooth surface. Cut to length: According to the production plan, the peeled high-quality long blanks are cut into the required lengths using a sawing machine. Heating and Surface Treatment: Uniform heating: The high-quality, fixed-length round billet is fed into a walking beam or ring furnace and heated to a uniform plastic deformation temperature of 1150-1250℃. High-pressure water curtain descaling: After exiting the furnace, the high-quality, high-temperature round billet is sent to a rotary all-around descaling device via a roller conveyor to thoroughly remove the iron oxide scale generated during the heating process, creating good interface conditions for subsequent piercing. Rotational plastic deformation perforation: Feeding and positioning: The high-temperature round billet, after being descaled by the rotary all-round descaling device, is fed into the multi-station rotary perforator through another roller conveyor mechanism. The high-temperature cleaned round billet is located at the perforation station of the multi-station rotary perforator. Station adjustment and alignment: The multi-station rotary piercing machine operates to adjust the high-temperature cleaned round billet to the station aligned with the piercing head, while providing loading space and foundation for the high-temperature round billet that has been descaled by the rotary all-round descaling machine. The rotating plastic deformation piercing head forms a continuous inner hole in the metal at the center of the inner round blank of the multi-station rotary piercing machine through plastic deformation. Separation and unloading: The multi-station rotary punch continues to run. The punched round billet moves to the unloading station, and then the formed thick-walled tube is smoothly pushed out of the chamber and falls onto the output roller table. Online finishing and cutting: Online Dimension and Defect Inspection: The tube enters the online monitoring station, where the outer diameter and ovality are measured by a laser scanner, and the wall thickness and internal defects are quickly scanned by a high-temperature ultrasonic flaw detector; Length planning and cutting: The detection data is transmitted to the central control system in real time. The system dynamically calculates and generates the optimal length cutting plan based on the size requirements and the location of the geometric irregular areas or minor defects at the beginning and end of the detection, so as to maximize the material utilization rate. Finally, the flying saw or hot saw performs precise cutting. Heat treatment and finishing: Solution treatment: For austenitic stainless steel, solution treatment is carried out in a protective atmosphere bright annealing furnace to obtain a uniform structure and optimal corrosion resistance. Straightening, flattening, and non-destructive testing: We perform routine straightening, flattening, and chamfering, as well as comprehensive ultrasonic, eddy current, and other non-destructive testing and hydrostatic testing to ensure the quality of the finished pipes.

2. The high yield preparation method for thick-walled stainless steel seamless pipes according to claim 1, wherein the rotary all-round descaling device drives the high-temperature round billet to rotate and, through its own dense water curtain formed by spraying, thoroughly removes the iron oxide scale generated during the heating process by means of thermal shock and mechanical impact, exposing a clean metal surface.

3. The high yield preparation method for thick-walled stainless steel seamless pipes according to claim 1, wherein the high-speed rotating piercing head moves towards the multi-station rotary piercing device, penetrates into the round billet cavity of the multi-station rotary piercing device, and advances axially towards the high-temperature cleaned round billet at a constant speed. Under the combined action of rotation and axial feeding, the piercing head forms a continuous inner hole in the metal at the center of the round billet through plastic deformation. The multi-station rotary piercing device cycles sequentially to realize continuous operation of the feeding, piercing, and unloading stations, ensuring the cycle time of production.

4. A device for preparing thick-walled stainless steel seamless pipes, characterized in that: The system includes an integrated platform (1), a multi-station rotary perforator (2), a rotary all-around descaling device (3), a roller conveyor mechanism (4), a roller plate (5), a roller assembly (6), a support frame (7), a hydraulic cylinder seat (8), a propulsion hydraulic cylinder (9), a propulsion integrated seat (10), a high-speed perforating shaft (11), a perforation driver (12), and a perforating head (13). The integrated platform (1) is fixedly installed above the support frame (7) and located on one side of the multi-station rotary perforator (2). The roller conveyor mechanism (4) is installed between the multi-station rotary perforator (2) and the rotary all-around descaling device (3). The integrated platform (1) is located on one side above the support frame (7). Two symmetrical roller conveyors (5) are installed, and a roller assembly (6) is rotatably installed between the two roller conveyors (5). The roller assembly (6) is connected to the output end of a synchronous driver installed on one of the roller conveyors (5). The hydraulic cylinder seat (8) is fixed on the integrated platform (1) by bolts and welding. The output end of the propulsion hydraulic cylinder (9) installed on the hydraulic cylinder seat (8) is connected to the propulsion integrated seat (10) slidably installed on the integrated platform (1). The output end of the perforation driver (12) installed on the propulsion integrated seat (10) is connected to one end of a high-speed perforation shaft (11). The other end of the high-speed perforation shaft (11) is equipped with the perforation head (13).

5. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 4, characterized in that: The multi-station rotary perforator (2) includes a disc cover (21), an anchor base (22), a perforation port (23), a discharge port (24), a feed port (25), a push port (26), a multi-station disc (27), a central shaft (28), a thrust bearing (29), a round blank cavity station (210), gear teeth (211), a drive gear (212), a drive shaft (213), and a worm gear motor (214). The disc cover (21) is fixed to the ground by the anchor base (22) installed below. One side of the disc cover (21) has the perforation port (23) and the discharge port (24) through it, and the other side has the feed port (25) through it. 5) and push port (26), the multi-station wheel (27) is rotatably installed inside the wheel cover (21) through two thrust bearings (29), and is rotatably connected to the central shaft (28) fixedly installed inside the wheel cover (21); the multi-station wheel (27) itself has a number of round blank cavity stations (210) through it, and the gear teeth (211) set in the middle of its outer surface mesh with the drive gear (212) installed on the drive shaft (213). The drive shaft (213) is rotatably installed inside the wheel cover (21), and any end of it is connected to the output end of the worm gear motor (214) installed outside the wheel cover (21).

6. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 5, characterized in that: The perforation port (23) and the ejector port (24) are formed on the surface of the wheel cover (21) near the perforating head (13) and the roller assembly (6). The perforation port (23) overlaps with the axis of the perforating head (13). The feed port (25) and the push port (26) are formed on the surface of the wheel cover (21) opposite to the perforation port (23) and the ejector port (24). The push port (26) and the ejector port (24) correspond to each other and are on the same horizontal line. The perforation port (23), the ejector port (24), and the feed port... (25) and push port (26) are both corresponding to the round blank cavity station (210) opened by the multi-station wheel (27). The push port (26) and the ejector port (24) are corresponding to the same round blank cavity station (210). The round blank that has been pierced inside the round blank cavity station (210) can be ejected from the ejector port (24) and smoothly transferred to the roller group (6). The piercing head (13) can perform plastic deformation piercing on the round blank in the round blank cavity station (210) through the piercing port (23).

7. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 5, characterized in that: A pusher support frame (215) is fixedly installed on the surface of the wheel cover (21) with a pusher opening (26). The output end of the ejector hydraulic cylinder (216) fixedly installed on the pusher support frame (215) is connected to the ejector disc (217). The ejector hydraulic cylinder (216) can drive the ejector disc (217) to move towards the pusher opening (26) and push the round blank with the hole completed inside the round blank cavity station (210) towards the ejector opening (24). The round blank cavity station (210) can limit the outer diameter of the round blank. The multi-station wheel (27) can be driven by the drive gear (212) and rotate around the center point of the central axis (28).

8. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 4, characterized in that: The rotary all-around descaling device (3) includes a descaling box (31), a high-pressure water tank (32), a high-pressure nozzle (33), an inspection door (34), a sludge collection box (35), a drive roller (36), and a high-temperature servo motor (37). The high-pressure water tank (32) fixedly installed on the side of the descaling box (31) is connected to several high-pressure nozzles (33) through a high-pressure pump and pipeline. The high-pressure nozzles (33) are installed inside the descaling box (31) and above the sludge collection box (35). The inspection door (34) is installed on the surface of the descaling box (31) with a sealed hinge. Two drive rollers (36) are rotatably installed inside the descaling box (31). One end of one of the drive rollers (36) is connected to the output end of the high-temperature servo motor (37) fixedly installed outside the descaling box (31).

9. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 8, characterized in that: Several high-pressure nozzles (33) are arranged in an arc path above the interior of the descaling box (31) and above the round billet channel, drive roller (36) and sludge collection box (35) that are opened through the descaling box (31). Two drive rollers (36) arranged opposite each other are arranged on the lower sides of the round billet channel and can roll contact with the lower sides of the round billet. The high-temperature servo motor (37) can drive the round billet to rotate by driving a single drive roller (36). Several high-pressure nozzles (33) generate high-pressure water jets that can act on the outer surface of the high-temperature round billet below. The oxide scale and sewage of the high-temperature round billet can fall downward and be collected by the sludge collection box (35).

10. The equipment for preparing thick-walled stainless steel seamless pipes according to claim 4, characterized in that: The round billet processed by the rotary all-around descaling device (3) can be smoothly transported to the multi-station turntable perforator (2) through the roller conveyor mechanism (4), and enter one of the round billet cavity stations (210) through the feed port (25). The roller conveyor mechanism (4) includes a conveyor support (41), a conveyor side plate (42), a conveyor wheel (43) and a synchronous drive transmission box (44). Two symmetrical conveyor side plates (42) are fixedly installed above the conveyor support (41). Several conveyor wheels (43) are rotatably installed between the two conveyor side plates (42). The same end of several conveyor wheels (43) is connected to the output end of one of the synchronous drive transmission boxes (44). The input end of the synchronous drive transmission box (44) is connected to the output end of the motor installed on its own outer shell.

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