Steel pipe cooling device and cooling method

Abstract

The application provides a steel pipe cooling device and a cooling method. The steel pipe cooling device comprises a water spraying cooling device and an atomization cooling bed connected in sequence, and the water spraying cooling device and the atomization cooling bed are used for sequentially performing inner surface water spraying cooling and outer surface atomization cooling on the steel pipe after sizing and reducing, so as to obtain a cooled steel pipe. The water spraying cooling device comprises a main groove body, a plurality of rotating supporting rollers, a water sprayer and a plurality of poking devices. The steel pipe cooling device has high cooling efficiency, can batch cool the inner surface and the outer surface of the steel pipe after sizing and reducing, rapidly and uniformly realizes overall cooling, reduces the problems of cooling efficiency reduction and uneven cooling caused by inner surface temperature recovery, and thus obtains a seamless steel pipe with excellent strength and toughness.

Description

Technical Field

[0001] This invention relates to the field of steel pipe technology, and more specifically, to a steel pipe cooling device and cooling method. Background Technology

[0002] Currently, the requirements for the strength, toughness, and dimensional accuracy of seamless steel pipe products are becoming increasingly stringent. As the wall thickness of steel pipes increases, even exceeding 30mm, online normalizing or tempering processes can no longer reliably meet the requirements of high-end seamless steel pipes for excellent strength and toughness matching.

[0003] To improve the strength and toughness of steel pipes, an online normalizing and rapid cooling process after sizing has been proposed. This process first refines the austenite grains through recrystallization using online normalizing technology, and then refines the grains of the air-cooled steel pipe after sizing. Accelerated cooling after sizing further prevents grain growth during the cooling process and forms an appropriate bainite structure. Ultimately, by controlling rolling and cooling, the strength and toughness of the steel pipe are improved simultaneously. However, this process still has shortcomings. First, it is impossible to precisely control the bainite content; if the metallographic structure is not properly controlled, both the strength and toughness of the steel pipe will deteriorate sharply. Second, the hollow cross-section of the steel pipe results in a larger cross-sectional size and a wider range of dimensional variations, making it impossible to cool all parts of the pipe uniformly. Uneven cooling during accelerated cooling will cause the steel pipe to bend and deform. Third, for thick-walled seamless steel pipes, the large heat storage capacity means that the reheating of the inner surface during through-cooling will reduce the cooling rate, leading to inconsistent cooling of the inner and outer surfaces, resulting in significant differences in the metallographic structure and properties of the inner and outer surfaces.

[0004] Therefore, there is an urgent need to develop an online rapid cooling device that can effectively and precisely cool steel pipes uniformly and rapidly, ultimately obtaining ultra-thick-walled seamless steel pipes with excellent strength and toughness. Summary of the Invention

[0005] The main objective of this invention is to provide a steel pipe cooling device and cooling method to solve the problem that thick-walled seamless steel pipes cannot be cooled quickly and uniformly due to their large heat storage capacity in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a steel pipe cooling device is provided, comprising a water spray cooling device and an atomizing cooling bed connected in sequence. The water spray cooling device and the atomizing cooling bed are used sequentially to perform water spray cooling on the inner surface and atomizing cooling on the outer surface of a steel pipe after sizing and reducing its diameter, respectively, to obtain a cooled steel pipe. The water spray cooling device includes a main tank, multiple rotating rollers, a water sprayer, and multiple material feeding devices. The main tank has a bottom and a receiving space enclosed by side walls, and the main tank is used to collect the cooling medium remaining after water spray cooling. The multiple rotating rollers are fixed to the bottom of one side of the main tank. Extending from the opening of the main tank, the rotating roller is used to place the reduced-diameter steel pipe and drive it to rotate; a water sprayer is set on the side wall of the main tank, and includes an inner nozzle and a water pump. The center of the straight section of the inner nozzle and the center of the first port of the reduced-diameter steel pipe are on the same horizontal line and are spaced apart. The water sprayer is used to spray water to cool the inner surface of the reduced-diameter steel pipe during its rotation, resulting in a water-cooled steel pipe; multiple material feeding devices are fixed at the bottom of the other side of the main tank and extend from the opening of the main tank. The material feeding devices are used to flip the reduced-diameter steel pipe onto the rotating roller.

[0007] Furthermore, the rotation direction of the cooling medium is opposite to the rotation direction of the steel pipe after the rotating idler roller drives the pipe to reduce its diameter; and / or, the rotation speed of the rotating idler roller is 30~300 rpm; and / or, the cooling medium for water spray cooling is water and / or brine; the flow rate of the cooling medium is 500~1000 m³ / h. 3 / h.

[0008] Furthermore, there is one inner nozzle, which includes a receiving section, an inclined section, and a straight section connected in sequence. The length ratio of the inclined section to the straight section is 1:1 to 1:2. The horizontal distance between the first port and the straight section is 100 to 500 mm. The diameter of the straight section is smaller than the inner diameter of the steel pipe after the diameter reduction. Along the radial direction of the steel pipe after the diameter reduction, the vertical distance between the inner surface of the steel pipe after the diameter reduction and the outer surface of the straight section is 10 to 40 mm.

[0009] Furthermore, multiple feeding devices are arranged at the bottom of the main tank near the first sidewall of the main tank and arranged sequentially along the horizontal direction of the first sidewall. The multiple feeding devices are connected by a first connecting device. Each feeding device has a flipping component and a feeding hook connected to the flipping component. Multiple rotating rollers are arranged on the opposite side of the feeding devices and away from the first sidewall, and are arranged sequentially along the horizontal direction of the first sidewall. The multiple rotating rollers are connected by a second connecting device.

[0010] Furthermore, an online conveyor roller table is also included between the water spray cooling device and the atomizing cooling bed; the material feeding device is fixed at the bottom of one side of the main trough near the online conveyor roller table, and the material feeding hook of the material feeding device is used to lift the water-sprayed steel pipe and flip it onto the online conveyor roller table and transport it to the atomizing cooling bed.

[0011] Furthermore, the atomizing cooling bed has multiple rows of atomizing nozzles, with multiple atomizing nozzles in each row arranged sequentially at intervals along the axial direction of the steel pipe after water spraying, and the number of atomizing nozzles in each row is 20 to 50; and / or, the atomization pressure of atomizing cooling is 0.2 to 2 MPa.

[0012] According to another aspect of the present invention, a method for cooling a steel pipe using the above-mentioned steel pipe cooling device is provided. The method includes: placing a reduced-diameter steel pipe onto a rotating roller via a feeding device, the rotating roller driving the reduced-diameter steel pipe to rotate, and a water sprayer spraying water onto the inner surface of the reduced-diameter steel pipe through an inner nozzle to cool it, thereby obtaining a water-sprayed steel pipe; and conveying the water-sprayed steel pipe to an atomizing cooling bed for atomizing cooling, thereby obtaining a cooled steel pipe.

[0013] Furthermore, the above method also includes: flipping the water-sprayed steel pipe onto the online conveyor rollers and conveying it to the atomizing cooling bed for atomizing cooling to obtain the cooled steel pipe.

[0014] Furthermore, the thickness of the steel pipe after sizing and reducing is 20~60mm; and / or, the temperature of the inner surface of the steel pipe after water spraying is 150~300℃ lower than the temperature of the inner surface of the steel pipe after sizing and reducing; and / or, the temperature of the inner surface of the steel pipe after water spraying is 100~260℃ lower than the temperature of the outer surface of the steel pipe after water spraying; and / or, the temperature of the inner surface of the steel pipe after water spraying is 550~650℃; and / or, the cooling rate of water spraying is 30~60℃ / s, and the flow rate of the cooling medium in water spraying is 500~1000m³. 3 / h.

[0015] Furthermore, the temperature of the outer surface of the cooled steel pipe is 100~260℃ lower than that of the outer surface of the steel pipe after water spraying, and the temperature difference between the outer surface and the inner surface of the cooled steel pipe is 0~50℃; and / or, the cooling rate of atomization cooling is 5~20℃ / s; and the speed at which the steel pipe passes through the atomization cooling bed after water spraying is 30~70s / step.

[0016] By applying the technical solution of this invention, the steel pipe cooling device of this application uses a rapid cooling process involving a water spray cooling device and an atomizing cooling bed connected in sequence to cool the inner and outer surfaces of the steel pipe after diameter reduction. This solves the problem of seamless steel pipes not being able to cool quickly and uniformly (in the prior art, ultra-thick-walled hot-rolled seamless steel pipes suffer from a large amount of heat storage during cooling, and the reheating of the inner surface during through-type cooling reduces the cooling rate, thus preventing the seamless steel pipe from cooling quickly and uniformly). Specifically, using a water spray cooling device to cool the inner surface of the steel pipe after diameter reduction not only allows for rapid cooling of the inner surface, causing the entire steel pipe to pass uniformly through the high-temperature phase transformation region, preventing the newly formed phase from growing and coarsening rapidly, but also maintains the hardened austenite at the phase transformation point. The new phase and carbonitrides surround the stress deformation nucleus, thereby greatly refining the grain structure. Specifically, the reduced-diameter steel pipe is flipped onto a rotating roller by a feeding device. The rotating roller then drives the reduced-diameter steel pipe to rotate. A water sprayer injects high-pressure cooling medium supplied by a water pump into the inner surface of the reduced-diameter steel pipe through an internal nozzle. Simultaneously, the cooling medium rotates at high speed on the inner surface of the steel pipe in the opposite direction to the rotation of the steel pipe, generating a large relative velocity with the inner surface of the reduced-diameter steel pipe in the circumferential direction. Under the action of large axial and tangential stresses, the high-pressure cooling medium advances at high speed in a spiral motion, rapidly and uniformly cooling the entire inner surface of the steel pipe. This also prevents the entire steel pipe from bending due to different cooling rates in different parts of the inner surface during the cooling process. Subsequently, an atomized cooling bed is used to atomize and cool the outer surface of the water-sprayed steel pipe, enabling rapid cooling of its outer surface or localized high-temperature areas. This achieves simultaneous, uniform, and rapid cooling of the inner and outer surfaces of the steel pipe to the set temperature. In addition, the steel pipe cooling device of this application has high cooling efficiency and can cool the inner and outer surfaces of the steel pipes after diameter reduction in batches, so that they can achieve rapid and uniform overall cooling, reducing the problem of cooling efficiency reduction and uneven cooling caused by the reheating of the inner surface, thereby obtaining seamless steel pipes with excellent strength and toughness. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A schematic front view of the water spray cooling device in Embodiment 1 of this application is shown;

[0019] Figure 2 A top view schematic diagram of the water spray cooling device in Embodiment 1 of this application is shown;

[0020] Figure 3 A schematic diagram of the internal nozzle structure in Embodiment 1 of this application is shown.

[0021] The above figures include the following reference numerals:

[0022] 1. Main trough; 2. Rotating roller; 3. Water sprayer; 4. Inner nozzle; 5. Material feeding device; 01. Receiving section; 02. Inclined section; 03. Straight section. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] As analyzed in the background section of this application, the prior art has the problem that thick-walled seamless steel pipes cannot be cooled quickly and evenly due to their large heat storage capacity. In order to solve the above problems, this application provides a steel pipe cooling device and cooling method.

[0025] In a typical embodiment of this application, a steel pipe cooling device is provided, comprising a water spray cooling device and an atomizing cooling bed connected in sequence. The water spray cooling device and the atomizing cooling bed are used sequentially to perform water spray cooling on the inner surface and atomizing cooling on the outer surface of the steel pipe after sizing and reducing its diameter, respectively, to obtain a cooled steel pipe. Wherein, as... Figures 1 to 3 As shown, the water spray cooling device includes: a main tank 1, multiple rotating rollers 2, a water sprayer 3, and multiple material feeding devices 5; the main tank 1 has a bottom and a receiving space enclosed by side walls, and the main tank 1 is used to collect the cooling medium remaining after water spray cooling; multiple rotating rollers 2 are fixed to the bottom of one side of the main tank 1 and extend in the direction of the opening of the main tank 1, and the rotating rollers 2 are used to place the reduced diameter steel pipe and drive the reduced diameter steel pipe to rotate; the water sprayer 3 is set on the side wall of the main tank 1, and the water sprayer 3 includes an inner nozzle 4 and a water pump, the center of the straight segment 03 of the inner nozzle 4 and the center of the first port of the reduced diameter steel pipe are on the same horizontal line and are spaced apart, the water sprayer 3 is used to spray water to cool the inner surface of the reduced diameter steel pipe during the rotation of the reduced diameter steel pipe, to obtain the water-sprayed steel pipe; multiple material feeding devices 5 are fixed to the bottom of the other side of the main tank 1 and extend in the direction of the opening of the main tank 1, and the material feeding devices 5 are used to flip the reduced diameter steel pipe onto the rotating rollers 2.

[0026] The steel pipe cooling device of this application utilizes a rapid cooling process involving a sequentially connected water spray cooling device and an atomizing cooling bed to cool the inner and outer surfaces of the steel pipe after sizing and reduction. This solves the problem of seamless steel pipes being unable to cool quickly and uniformly (in the prior art, ultra-thick-walled hot-rolled seamless steel pipes experience a large amount of heat storage during cooling, and the reheating of the inner surface during through-type cooling reduces the cooling rate, thus preventing rapid and uniform cooling). Specifically, the water spray cooling device cools the inner surface of the sizing and reduction steel pipe, which not only rapidly cools the inner surface and causes the entire steel pipe to pass uniformly through the high-temperature phase transformation region, preventing the newly formed phase from growing and coarsening rapidly, but also retains the hardened austenite at the phase transformation point. The new phase and carbonitrides surround the stress deformation nucleus, thereby significantly refining the grain structure. Specifically, the reduced-diameter steel pipe is flipped onto the rotating roller 2 by the feeding device 5. The rotating roller 2 then drives the reduced-diameter steel pipe to rotate. The water sprayer 3 sprays high-pressure cooling medium supplied by the water pump into the inner surface of the reduced-diameter steel pipe through the inner nozzle 4. At the same time, the cooling medium rotates at high speed in the opposite direction to the rotation of the steel pipe on the inner surface. It generates a large relative velocity with the inner surface of the reduced-diameter steel pipe in the circumferential direction. Under the action of large axial and tangential stresses, the high-pressure cooling medium advances at high speed in a spiral shape, so that the inner surface of the entire steel pipe is cooled quickly and evenly. At the same time, it can also prevent the entire steel pipe from bending due to different cooling rates in different parts of the inner surface during the cooling process. The outer surface of the water-sprayed steel pipe is atomized and cooled by the atomized cooling bed, so that the outer surface or local high temperature areas are cooled quickly, thereby achieving simultaneous, uniform and rapid cooling of the inner and outer surfaces of the steel pipe to the set temperature. In addition, the steel pipe cooling device of this application has high cooling efficiency and can cool the inner and outer surfaces of the steel pipes after diameter reduction in batches, so that they can achieve rapid and uniform overall cooling, reducing the problem of cooling efficiency reduction and uneven cooling caused by the reheating of the inner surface, thereby obtaining seamless steel pipes with excellent strength and toughness.

[0027] In addition, the steel pipe after sizing or reducing diameter is either a sizing steel pipe or a reducing steel pipe.

[0028] In one embodiment of this application, the rotation direction of the cooling medium is opposite to the rotation direction of the steel pipe after the diameter reduction is driven by the rotating idler roller 2; and / or, the rotation speed of the rotating idler roller 2 is 30~300 rpm; and / or, the cooling medium for water spray cooling is water and / or brine; the flow rate of the cooling medium is 500~1000 m³ / h. 3 / h.

[0029] Preferably, controlling the rotation direction of the cooling medium to be opposite to the rotation direction of the steel pipe after the diameter reduction driven by the rotating roller 2, and the rotation speed of the rotating roller 2 within the above range, helps to further increase the relative speed between the cooling medium and the inner surface of the steel pipe after the diameter reduction in the circumferential direction. This allows the high-pressure cooling medium to advance at high speed in a spiral shape under the action of large axial stress and tangential stress, so that the inner surface of the entire steel pipe is cooled quickly and evenly, thereby improving the cooling effect of water spray cooling.

[0030] Preferably using a cooling medium within the aforementioned range for water spray cooling helps improve the cooling effect. The flow rate of the cooling medium helps improve the uniformity and speed of the cooling rate of the steel pipe. Too low a flow rate leads to insufficient cooling efficiency, resulting in a slow cooling rate; too high a flow rate may cause energy waste, increase production costs, and even affect the uniformity of cooling. Therefore, a flow rate within the aforementioned range of the cooling medium helps improve the speed and uniformity of water spray cooling. For ultra-thick-walled hot-rolled seamless steel pipes, the flow rate of the cooling medium within the aforementioned range helps provide a sufficient cooling rate, reducing abnormal microstructures caused by excessively fast or slow cooling, such as the formation of upper bainite or coarse grains.

[0031] In one embodiment of this application, there is one inner nozzle 4, which includes a receiving section 01, an inclined section 02, and a straight section 03 connected in sequence. The length ratio of the inclined section 02 to the straight section 03 is 1:1 to 1:2. The horizontal distance between the first port and the straight section 03 is 100 to 500 mm. The diameter of the straight section 03 is smaller than the inner diameter of the steel pipe after the diameter reduction. Along the radial direction of the steel pipe after the diameter reduction, the vertical distance between the inner surface of the steel pipe after the diameter reduction and the outer surface of the straight section 03 is 10 to 40 mm.

[0032] The preferred number of internal nozzles 4 within the above range helps to ensure that the cooling medium and the inner surface of the steel pipe are in uniform and sufficient contact, thereby improving the uniformity of water spray cooling.

[0033] The preferred internal nozzle comprises a receiving section 01, an inclined section 02, and a straight section 03 connected in sequence. The receiving section 01 and the inclined section 02 help to transform the high-pressure cooling medium provided by the water pump into high-pressure water jets of different diameters suitable for steel pipes of different specifications, and change the stress state of the water flow. The straight section 03 helps to stabilize the axial flow rate of the cooling medium on the inner surface of the steel pipe after the diameter reduction, and increases the axial pressure of the water flow, thereby improving the uniformity and speed of cooling. Controlling the length ratio of the inclined section 02 and the straight section 03 within the above-mentioned range helps to generate a large tangential stress in the water flow when the high-pressure cooling medium enters the straight section 03 after the inclined section 02, thereby better driving the high-pressure cooling medium to rotate at high speed in the straight section and advance in a high-speed spiral shape on the inner surface of the steel pipe after the diameter reduction, so that the entire inner surface of the steel pipe is cooled quickly and uniformly.

[0034] Preferably controlling the horizontal distance between the first port and the straight segment 03 within the aforementioned range helps reduce unnecessary diffusion or loss of the cooling medium before it reaches the inner surface of the steel pipe, while simultaneously achieving rapid and complete cooling coverage of the entire inner surface of the steel pipe, thereby enhancing the effectiveness and efficiency of cooling. Preferably, the diameter of the straight segment 03 is smaller than the inner diameter of the steel pipe after the reduction, which helps the cooling medium to be sprayed evenly and quickly onto the inner surface of the steel pipe after the reduction. Further preferably, the vertical distance between the inner surface of the steel pipe and the outer surface of the straight segment 03 along the radial direction of the steel pipe is within the aforementioned range, which helps to control the angle of the cooling medium spray, ensuring it evenly covers the entire inner surface of the steel pipe. This reduces the risk of water splashing to the outside due to excessively small gaps, resulting in insufficient effective cooling water volume on the inner surface of the steel pipe, or excessively large gaps preventing the cooling medium from completely filling the inner surface of the steel pipe, thus reducing the cooling effect or cooling uniformity.

[0035] The angle between the inclined section 02 and the straight section 03 is preferably 110°~160°, which helps to generate tangential stress in the high-pressure medium provided by the high-pressure water pump when entering the straight section 03 from the inclined section 02. This allows the high-pressure cooling medium to advance rapidly in a spiral shape in the straight section 03 or on the inner surface of the steel pipe, thereby achieving rapid and uniform cooling of the inner surface of the steel pipe.

[0036] In one embodiment of this application, a plurality of feeding devices 5 are disposed at the bottom of the main trough 1 near the first side wall of the main trough 1 and arranged sequentially along the horizontal direction of the first side wall. The plurality of feeding devices 5 are connected by a first connecting device. The feeding device 5 has a flipping component and a feeding hook connected to the flipping component. A plurality of rotating rollers 2 are disposed on the side opposite to the feeding devices 5 and away from the first side wall, and arranged sequentially along the horizontal direction of the first side wall. The plurality of rotating rollers 2 are connected by a second connecting device.

[0037] The material feeding device 5 has a flipping component and a feeding hook, which helps to flip the steel pipe after the diameter reduction onto the rotating idler roller 2. Connecting multiple rotating idler rollers 2 via a second connecting device helps to keep the rotation speed of the multiple rotating idler rollers 2 consistent, thereby improving the uniformity and consistency of water spray cooling. Preferably, the multiple rotating idler rollers 2 are fixed at the bottom center of the main trough 1.

[0038] In one embodiment of this application, an online conveyor roller table is further included between the water spray cooling device and the atomizing cooling bed; the material feeding device is fixed at the bottom of one side of the main trough near the online conveyor roller table, and the material feeding hook of the material feeding device is used to lift the water-sprayed steel pipe and flip it onto the online conveyor roller table and transport it to the atomizing cooling bed.

[0039] An online conveyor roller conveyor is designed between the water spray cooling device and the atomized cooling bed, which helps the steel pipe to transition smoothly and be transported efficiently between different cooling stages, while maintaining the straightness and dimensional stability of the steel pipe during the cooling process.

[0040] The material feeding device 5 is equipped with a tilting component and a feeding hook. After being cooled by water spraying, the steel pipe is fed onto the feeding device 5 and tilted by the tilting component onto the online conveyor rollers for delivery to the atomizing cooling bed. The tilting component helps improve the safety and stability of the steel pipe during the tilting process, reducing mechanical damage or deformation of the steel pipe caused by improper operation.

[0041] In one embodiment of this application, the atomizing cooling bed has multiple rows of atomizing nozzles, with multiple atomizing nozzles in each row arranged sequentially at intervals along the axial direction of the steel pipe after water spraying, and the number of atomizing nozzles in each row is 20 to 50; and / or, the atomizing pressure of atomizing cooling is 0.2 to 2 MPa.

[0042] The preferred layout and number of atomizing nozzles within the above-mentioned range help to fully cover the outer surface of the steel pipe after water spraying, thereby improving the cooling effect of atomization cooling. Preferably controlling the atomization pressure within the above-mentioned range helps to generate fine droplets, thereby increasing the contact area with the outer surface of the steel pipe after water spraying, and thus accelerating the cooling process.

[0043] The preferred method is to transport the cooled steel pipe to a large cooling bed for air cooling to obtain a seamless steel pipe.

[0044] In another typical embodiment of this application, a method for cooling a steel pipe using the above-mentioned steel pipe cooling device is provided. The method includes: placing the reduced diameter steel pipe onto a rotating roller 2 via a feeding device 5; the rotating roller 2 driving the reduced diameter steel pipe to rotate; a water sprayer 3 spraying water onto the inner surface of the reduced diameter steel pipe through an inner nozzle 4 to cool it, thereby obtaining a water-sprayed steel pipe; and conveying the water-sprayed steel pipe to an atomizing cooling bed for atomizing cooling, thereby obtaining a cooled steel pipe.

[0045] This application utilizes the aforementioned steel pipe cooling device to spray water onto the inner surface of the reduced-diameter steel pipe. This not only rapidly cools the inner surface, causing the entire steel pipe to uniformly pass through the high-temperature phase transformation region, preventing the newly formed phase from growing and coarsening rapidly, but also preserves the hardened austenite to the phase transformation point. New phases and carbonitrides surround the stress nuclei, significantly refining the grain structure. Atomized cooling of the outer surface of the pipe after water spraying allows for rapid cooling of the outer surface or localized high-temperature areas, achieving simultaneous, uniform, and rapid cooling of both the inner and outer surfaces to the set temperature. In summary, this cooling method significantly improves the cooling efficiency of the steel pipe, enabling online and batch cooling of both the inner and outer surfaces of the reduced-diameter steel pipe. This rapid and uniform overall cooling reduces the decrease in cooling efficiency and uneven cooling caused by inner surface reheating, resulting in seamless steel pipes with excellent strength and toughness.

[0046] In one embodiment of this application, the above method further includes: using the material feeding hook of the material feeding device 5 to pull up the water-sprayed steel pipe and flip it onto the online conveying roller and convey it to the atomizing cooling bed for atomizing cooling, thereby obtaining the cooled steel pipe.

[0047] The material feeding device 5 pulls up the water-cooled steel pipe, flips it onto the online conveyor rollers, and sends it to the atomizing cooling bed. The online conveyor rollers between the water-cooling device and the atomizing cooling bed facilitate a smooth transition and efficient transport of the steel pipe between different cooling stages, while maintaining the straightness and dimensional stability of the steel pipe during the cooling process.

[0048] In one embodiment of this application, the thickness of the steel pipe after sizing and reducing is 20-60 mm; and / or, the temperature of the inner surface of the steel pipe after water spraying is 150-300°C lower than the temperature of the inner surface of the steel pipe after sizing and reducing; and / or, the temperature of the inner surface of the steel pipe after water spraying is 100-260°C lower than the temperature of the outer surface of the steel pipe after water spraying; and / or, the temperature of the inner surface of the steel pipe after water spraying is 550-650°C; and / or, the cooling rate of water spraying is 30-60°C / s, and the flow rate of the cooling medium in water spraying is 500-1000 m³ / s. 3 / h.

[0049] It is preferable to control the temperature of the inner surface of the steel pipe after water spraying to be 150-300°C lower than the temperature of the inner surface of the steel pipe after diameter reduction. Controlling the cooling rate and the flow rate of the cooling medium in water spraying within the above range helps to improve the cooling speed of water spraying, so that the temperature of the inner surface of the steel pipe after water spraying reaches the above range and is lower than the temperature of its outer surface. This allows the entire steel pipe to pass through the high-temperature phase transformation region evenly, alleviating the rapid growth and coarsening of the newly formed phase. It also helps to retain the hardened austenite to the phase transformation point, with the new phase and carbonitrides surrounding the stress deformation nucleus, thereby further refining the grain structure.

[0050] In one embodiment of this application, the temperature of the outer surface of the cooled steel pipe is 100-260°C lower than that of the outer surface of the steel pipe after water spraying, and the temperature difference between the outer surface and the inner surface of the cooled steel pipe is 0-50°C; and / or, the cooling rate of the atomization cooling is 5-20°C / s; and the speed at which the steel pipe passes through the atomization cooling bed after water spraying is 30-70s / step.

[0051] Ideally, the temperature of the outer surface of the cooled steel pipe should be 100-260°C lower than that of the steel pipe after water spraying. Controlling the cooling rate of the atomizing cooling and the speed at which the steel pipe passes through the atomizing bed after water spraying within this range helps to rapidly cool the outer surface or localized high-temperature areas of the steel pipe after water spraying. This ensures that the inner and outer surfaces of the cooled steel pipe are simultaneously, uniformly, and rapidly cooled to the set temperature, and the temperature difference between the inner and outer surfaces is controlled within the aforementioned range. This, in turn, promotes the synchronicity and uniformity of the phase transformation process inside and outside the steel pipe. The atomizing cooling bed is a stepping-type device, where s / step represents the number of seconds taken to advance one step (one step distance). For example, 30s / step means advancing one step distance every 30 seconds.

[0052] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0053] Example 1

[0054] The raw materials for seamless steel pipes are smelted by mass percentage according to the following composition: 0.15% C, 0.40% Si, 1.60% Mn, 0.07% V, 0.04% Nb, 0.04% Al, 0.005% Ti, 0.15% Cr, 0.05% Ni, 0.05% Mo, 0.001% P, 0.005% S, 0.003% N, with unavoidable impurities totaling ≤0.15% and the balance being Fe. The smelting process involves electric furnace smelting, LF refining, VD vacuum degassing, and continuous casting to obtain billets. The starting temperature for continuous casting is 1560℃.

[0055] The billet is sequentially heated and then pierced in a conical shape at 1200℃ to obtain a rough tube. The first heating process includes: heating in a ring furnace sequentially through a heat recovery section, preheating section I, heating section I, heating section II, heating section III, soaking section I, and soaking section II; the temperature in the heat recovery section is 300℃ (following the furnace temperature), the temperature in preheating section I is 500℃, the temperature in heating section I is 750℃, the temperature in heating section II is 1000℃, the temperature in heating section III is 1200℃, the temperature in soaking section I is 1250℃, the temperature in soaking section II (final temperature) is 1280℃, the billet exits the furnace at 1280℃, and the total heating time for the first heating is 4.5 hours.

[0056] The rough tube is rolled at 1000℃ using a continuous rolling mill to obtain a blank tube. The blank tube undergoes a first cooling process on a small cooling bed until its temperature reaches 550℃. After the first cooling, the blank tube undergoes a second heating process in a walking beam furnace until it reaches a temperature higher than that of tube A. c3 The temperature is 55℃ higher, resulting in a second heated rough tube at 910℃. This second heated rough tube is then placed in a sizing mill and sized at a temperature higher than A. c3The sizing is performed at a temperature above 20°C in the non-recrystallization zone to obtain the sizing steel pipe. Among them, A... c3 The temperature is 855℃.

[0057] A steel pipe cooling device, comprising a water spray cooling unit and an atomizing cooling bed connected in sequence, is used to sequentially perform water spray cooling on the inner surface and atomizing cooling on the outer surface of the sized steel pipe. Specifically, the device employs... Figure 1 and Figure 2 The water spray cooling device shown cools the inner surface of the sized steel pipe by spraying water. The water spray cooling device includes: a main trough 1, multiple rotating rollers 2, water sprayers 3, and multiple material feeding devices 5. Ten material feeding devices 5 are arranged at the bottom of the main trough 1 near the first sidewall of the main trough 1, and are sequentially arranged along the horizontal direction of the first sidewall. The ten material feeding devices 5 are connected by a first connecting device. Each material feeding device 5 has a flipping component and a material feeding hook connected to the flipping component. Ten rotating rollers 2 are located at the bottom center of the main trough 1, opposite to the material feeding devices 5, and away from the first sidewall. They are sequentially arranged along the horizontal direction of the first sidewall. The ten rotating rollers 2 are connected by a second connecting device.

[0058] The sized steel pipe is flipped onto the rotating idler roller 2 by the feeding device 5. The water sprayer 3 has an inner nozzle 4, which includes a receiving section 01, an inclined section 02, and a straight section 03 connected in sequence, such as... Figure 3 As shown, the length ratio of the inclined segment 02 to the straight segment 03 is 1:1.5, and the angle between the inclined segment and the straight segment is 135°. The center of the straight segment 03 and the center of the first end of the sized steel pipe are on the same horizontal line, and the horizontal distance between the first end of the sized steel pipe and the straight segment 03 is 300mm. The diameter of the straight segment 03 is smaller than the inner diameter of the sized steel pipe, and the vertical distance between the inner surface of the sized steel pipe and the outer surface of the straight segment 03 along the radial direction of the sized steel pipe is 15mm. After the sized steel pipe is placed on the rotating roller 2, it rotates clockwise at a speed of 150rpm. At the same time, the water pump of the water sprayer 3 pressurizes the cooling medium water to achieve a flow rate of 800m³ / h. 3 The water jet, passing sequentially through the receiving section 01, inclined section 02, and straight section 03 of the inner nozzle 4, forms a high-speed counter-clockwise rotating water flow that is sprayed into the inner surface of the sized steel pipe for water cooling, raising the temperature of the inner surface of the steel pipe to 600℃. The cooling rate is 50℃ / s, and the water flow rate is 800m³ / s. 3 / h. After the water spray cooling is completed, the main tank 1 collects the remaining water.

[0059] The material feeding device 5 uses a feeding hook to feed the water-sprayed steel pipe onto the feeding device 5, and then flips it onto the online conveyor rollers via a flipping component and transports it to the atomizing cooling bed. The outer surface of the water-sprayed steel pipe is then atomized and cooled, with the cooling temperature set at 600℃. The atomizing cooling bed has multiple rows of atomizing nozzles, each row arranged parallel to the axial direction of the water-sprayed steel pipe, with 30 nozzles per row. The atomization pressure is 1 MPa, the cooling rate is 10℃ / s, and the speed at which the water-sprayed steel pipe passes through the atomizing bed is 50 s / step.

[0060] After cooling, the steel pipe is transported to a large cooling bed for air cooling to obtain a seamless steel pipe with a thickness of 50mm.

[0061] Example 2

[0062] The difference from Example 1 is that the rotational speed of the rotating roller 2 is 300 rpm, and a seamless steel pipe is finally obtained.

[0063] Example 3

[0064] The difference from Example 1 is that the rotational speed of the rotating roller 2 is 20 rpm, and a seamless steel pipe is finally obtained.

[0065] Example 4

[0066] The difference from Example 1 is that the inner nozzle 4 includes a receiving section 01, an inclined section 02, and a straight section 03 connected in sequence. The length ratio of the inclined section 02 to the straight section 03 is 1:2, the included angle between the inclined section 02 and the straight section 03 is 110°, the horizontal distance between the first end of the sized steel pipe and the straight section 03 is 500mm, and the vertical distance between the inner surface of the sized steel pipe and the outer surface of the straight section 03 along the radial direction of the sized steel pipe is 40mm, thus obtaining a seamless steel pipe.

[0067] Example 5

[0068] The difference from Example 1 is that the inner nozzle 4 includes a receiving section 01, an inclined section 02 and a straight section 03 connected in sequence. The length ratio of the inclined section 02 to the straight section 03 is 1:0.7, the included angle between the inclined section 02 and the straight section 03 is 165°, the horizontal distance between the first end of the sizing steel pipe and the straight section 03 is 600mm, and the vertical distance between the inner surface of the sizing steel pipe and the outer surface of the straight section 03 along the radial direction of the sizing steel pipe is 5mm, thus obtaining a seamless steel pipe.

[0069] Example 6

[0070] The difference from Example 1 is that the cooling rate of the water spray cooling is 60°C / s, and the water flow rate in the water spray cooling is 1000 m³ / s. 3 / h, finally obtaining seamless steel pipes.

[0071] Example 7

[0072] The difference from Example 1 is that the cooling rate of the water spray cooling is 20°C / s, and the water flow rate in the water spray cooling is 300 m³ / s. 3 / h, finally obtaining seamless steel pipes.

[0073] Example 8

[0074] The difference from Example 1 is that the outer surface of the steel pipe after water spraying is subjected to atomized cooling. The atomization pressure of the atomization cooling is 2MPa, the cooling rate of the atomization cooling is 20℃ / s, and the speed at which the steel pipe passes through the atomization bed after water spraying is 35s / step, finally obtaining a seamless steel pipe.

[0075] Example 9

[0076] The difference from Example 1 is that the outer surface of the steel pipe after water spraying is subjected to atomized cooling. The atomization pressure of the atomization cooling is 0.15MPa, the cooling rate of the atomization cooling is 25℃ / s, and the speed at which the steel pipe passes through the atomization bed after water spraying is 75s / step, finally obtaining a seamless steel pipe.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the outer surface of the sized steel pipe is rapidly cooled by a through-cooling method to obtain a seamless steel pipe.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that only the outer surface of the sized steel pipe is atomized and cooled, while the inner surface is not cooled separately, resulting in a seamless steel pipe.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the steel pipe after water spraying is directly transported to a large cooling bed for air cooling to obtain a seamless steel pipe.

[0083] Test method:

[0084] Average grain size test: Tested according to GB / T 6394 standard.

[0085] Mechanical properties (tensile strength, yield strength, elongation) and low-temperature impact performance tests: tested according to GB / T228.1 and GB / T 229 standards respectively.

[0086] In the above embodiments and comparative examples, the temperatures of the inner and outer surfaces of the steel pipes after sizing were all 850℃. The temperatures of the inner and outer surfaces of the steel pipes after water spraying and cooling are shown in Table 1. The performance test results are shown in Table 2.

[0087] Table 1

[0088]

[0089] Table 2

[0090]

[0091] As can be seen from the above, in Comparative Example 1, only the conventional external surface cooling method was used. Due to the large heat storage capacity of the thick-walled tube, the reheating of the inner surface prevented rapid cooling of the steel pipe in the high-temperature section. This led to rapid growth and coarsening of the steel pipe's microstructure during phase transformation, and the hardened austenite rapidly reverted and softened at high temperatures, ultimately significantly deteriorating the steel pipe's strength and toughness. In Comparative Example 2, only the outer surface of the steel pipe was cooled by atomization. Similarly, the large heat storage capacity of the thick-walled tube significantly reduced the cooling rate due to the reheating of the inner surface. This resulted in only a localized area of ​​the steel pipe reaching the set temperature for a short time, while the overall temperature of the steel pipe remained high. Ultimately, the rapidly growing grains deteriorated the steel pipe's strength and toughness. In Comparative Example 3, only the inner surface was cooled by water spraying. The temperature on the outer surface and in some localized areas of the steel pipe was high, resulting in a low overall cooling rate. Furthermore, there were significant differences in temperature and cooling rate at different locations. Ultimately, the steel pipe's grains were not refined, and its strength and toughness were not significantly improved.

[0092] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0093] The steel pipe cooling device of this application utilizes a rapid cooling process involving a sequentially connected water spray cooling device and an atomizing cooling bed to cool the inner and outer surfaces of the steel pipe after sizing and reduction. This solves the problem of seamless steel pipes being unable to cool quickly and uniformly (in the prior art, ultra-thick-walled hot-rolled seamless steel pipes experience a large amount of heat storage during cooling, and the reheating of the inner surface during through-type cooling reduces the cooling rate, thus preventing rapid and uniform cooling). Specifically, the water spray cooling device cools the inner surface of the sizing and reduction steel pipe, which not only rapidly cools the inner surface and causes the entire steel pipe to pass uniformly through the high-temperature phase transformation region, preventing the newly formed phase from growing and coarsening rapidly, but also retains the hardened austenite at the phase transformation point. The new phase and carbonitrides surround the stress deformation nucleus, thereby significantly refining the grain structure. Specifically, the reduced-diameter steel pipe is flipped onto a rotating roller by a feeding device. The rotating roller then drives the reduced-diameter steel pipe to rotate. A water sprayer injects high-pressure cooling medium supplied by a water pump into the inner surface of the reduced-diameter steel pipe through an internal nozzle. Simultaneously, the cooling medium rotates at high speed in the opposite direction of the steel pipe's rotation, generating a large relative velocity with the inner surface of the reduced-diameter steel pipe in the circumferential direction. Under the action of large axial and tangential stresses, the high-pressure cooling medium advances at high speed in a spiral motion, rapidly and uniformly cooling the entire inner surface of the steel pipe. This also prevents the entire steel pipe from bending due to different cooling rates at different parts of the inner surface during the cooling process. A misting cooling bed further atomizes and cools the outer surface of the water-sprayed steel pipe, rapidly cooling its outer surface or localized high-temperature areas. This ensures that the inner and outer surfaces of the steel pipe are simultaneously, uniformly, and rapidly cooled to the set temperature. In addition, the steel pipe cooling device of this application has high cooling efficiency and can cool the inner and outer surfaces of the steel pipes after diameter reduction in batches, so that they can achieve rapid and uniform overall cooling, reducing the problem of cooling efficiency reduction and uneven cooling caused by the reheating of the inner surface, thereby obtaining seamless steel pipes with excellent strength and toughness.

[0094] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A steel pipe cooling device, characterized in that, The steel pipe cooling device includes a water spray cooling device and an atomizing cooling bed connected in sequence. The water spray cooling device and the atomizing cooling bed are used sequentially to perform water spray cooling on the inner surface and atomizing cooling on the outer surface of the steel pipe after sizing and reducing its diameter, resulting in a cooled steel pipe. The water spray cooling device includes: The main tank (1) has a bottom and a receiving space enclosed by side walls, the main tank (1) being used to collect the cooling medium remaining after the water spray cooling; Multiple rotating rollers (2) are fixed to the bottom of one side of the main trough (1) and extend from the direction of the opening of the main trough (1). The rotating rollers (2) are used to place the steel pipe after the diameter reduction and drive the steel pipe after the diameter reduction to rotate. A water sprayer (3) is installed on the side wall of the main tank (1). The water sprayer (3) includes an inner nozzle (4) and a water pump. The center of the straight section (03) of the inner nozzle (4) and the center of the first port of the reduced diameter steel pipe are on the same horizontal line and are spaced apart. The water sprayer (3) is used to spray water to cool the inner surface of the reduced diameter steel pipe during the rotation of the reduced diameter steel pipe to obtain the water-sprayed steel pipe. Multiple material feeding devices (5) are fixed to the bottom of the other side of the main trough (1) and extend from the direction of the opening of the main trough (1). The material feeding devices (5) are used to flip the steel pipe after the diameter reduction onto the rotating roller (2). The inner nozzle (4) includes a receiving section (01), an inclined section (02) and a straight section (03) connected in sequence, and the length ratio of the inclined section (02) and the straight section (03) is 1:1 to 1:2; The horizontal distance between the first port and the straight segment (03) is 100~500mm; the diameter of the straight segment (03) is smaller than the inner diameter of the steel pipe after the diameter reduction, and the vertical distance between the inner surface of the steel pipe after the diameter reduction and the outer surface of the straight segment (03) is 10~40mm along the radial direction of the steel pipe after the diameter reduction.

2. The steel pipe cooling device according to claim 1, characterized in that, The rotation direction of the cooling medium is opposite to the rotation direction of the steel pipe after the diameter reduction is driven by the rotating idler roller (2); and / or, the rotation speed of the rotating idler roller (2) is 30~300 rpm; and / or, the cooling medium for water spray cooling is water and / or brine; the flow rate of the cooling medium is 500~1000 m³ / h. 3 / h.

3. The steel pipe cooling device according to claim 1, characterized in that, The number of the inner nozzle (4) is 1.

4. The steel pipe cooling device according to claim 1, characterized in that, Multiple feeding devices (5) are disposed at the bottom of the main tank (1) near the first side wall of the main tank (1) and arranged sequentially along the horizontal direction of the first side wall. The multiple feeding devices (5) are connected by a first connecting device. Each feeding device (5) has a flipping component and a feeding hook connected to the flipping component. Multiple rotating rollers (2) are disposed on the opposite side of the feeding device (5) and away from the first sidewall, and are arranged sequentially along the horizontal direction of the first sidewall. The multiple rotating rollers (2) are connected by a second connecting device.

5. The steel pipe cooling device according to claim 4, characterized in that, An online conveyor roller conveyor is also included between the water spray cooling device and the atomizing cooling bed; The material feeding device (5) is fixed at the bottom of the main trough (1) near the online conveying roller. The material feeding hook of the material feeding device (5) is used to lift the water-sprayed steel pipe and flip it onto the online conveying roller and transport it to the atomizing cooling bed.

6. The steel pipe cooling device according to claim 1, characterized in that, The atomizing cooling bed has multiple rows of atomizing nozzles, with multiple atomizing nozzles in each row arranged sequentially at intervals along the axial direction of the water-sprayed steel pipe, and the number of atomizing nozzles in each row is 20 to 50; and / or, the atomizing pressure of the atomizing cooling is 0.2 to 2 MPa.

7. A method for cooling a steel pipe using the steel pipe cooling device according to any one of claims 1 to 6, characterized in that, The method includes: After the diameter reduction is achieved, the steel pipe is placed on the rotating roller (2) by the feeding device (5). The rotating roller (2) drives the steel pipe to rotate. The water sprayer (3) sprays water to cool the inner surface of the steel pipe through the inner nozzle (4) to obtain the water-sprayed steel pipe. The water-sprayed steel pipe is then transported to an atomizing cooling bed for atomizing cooling to obtain a cooled steel pipe.

8. The method according to claim 7, characterized in that, The method further includes: flipping the water-sprayed steel pipe onto the online conveying roller and conveying it to the atomizing cooling bed through the material feeding device (5) to perform the atomizing cooling, thereby obtaining the cooled steel pipe.

9. The method according to claim 7 or 8, characterized in that, The thickness of the steel pipe after the sizing and reduction is 20~60mm; and / or, the temperature of the inner surface of the steel pipe after water spraying is 150~300℃ lower than the temperature of the inner surface of the steel pipe after the sizing and reduction; and / or, the temperature of the inner surface of the steel pipe after water spraying is 100~260℃ lower than the temperature of the outer surface of the steel pipe after water spraying; and / or, the temperature of the inner surface of the steel pipe after water spraying is 550~650℃; and / or, the cooling rate of the water spray cooling is 30~60℃ / s, and the flow rate of the cooling medium in the water spray cooling is 500~1000m³. 3 / h.

10. The method according to claim 7 or 8, characterized in that, The temperature of the outer surface of the cooled steel pipe is 100-260°C lower than that of the outer surface of the steel pipe after water spraying, and the temperature difference between the outer surface and the inner surface of the cooled steel pipe is 0-50°C; and / or, the cooling rate of the atomization cooling is 5-20°C / s; the speed at which the steel pipe passes through the atomization cooling bed after water spraying is 30-70s / step.

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