Preparation method and preparation system of high-pressure flange

Abstract

The invention discloses a high-pressure flange manufacturing method and a high-pressure flange manufacturing system, and belongs to the technical field of high-performance ring forging manufacturing, and the high-pressure flange manufacturing method comprises the steps that S1, a thin ring casting is centrifugally cast; s2, cooling and crystallizing the casting; s3, the casting is heated and remelted, and a semi-solid annular blank is obtained; s4, the semi-solid annular blank is rotationally rolled through a rolling machine, and a rolled blank is obtained; s5, ring rolling is conducted on the flattened blank through a vertical ring rolling machine, and a chambering blank is obtained; s6, the chambering blank is subjected to flat rolling through a flat rolling machine, and a flange forging stock is obtained; and S7, the flange forging stock is subjected to temperature control heat treatment, and the high-pressure flange forging is obtained. The preparation system comprises a feeding trolley, a centrifugal casting unit, a cooling conveying device, a heating furnace, a flattening machine, a vertical ring rolling machine, a flat rolling machine, a flange forge piece rail flat car, a heat preservation heat treatment bin and the like. The thin ring casting can be subjected to the follow-up process without being completely cooled, the production efficiency is improved, waste heat of the casting can be used, and the operation rhythm cannot be affected due to the fact that a forging and pressing procedure link is omitted.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing high-performance ring forgings, and particularly to a method and a system for preparing a high-pressure flange. Background Art

[0002] Medium-sized high-pressure flanges (DN200 - DN500), as key connecting and supporting structural components, are widely used in major equipment manufacturing fields such as aerospace, wind power generation, and pipeline systems. At present, the domestic production processes for medium-sized high-pressure flanges mainly include two types: profile forging and casting forging and rolling. One is the profile forging process, which uses medium-thick plate profiles or scrap as raw materials. After cutting, they are heated as a whole, and then the flange is manufactured through overall forging of the steel billet, forging and punching, vertical shaft hole expansion, and flat rolling for shaping. The other is the casting forging and rolling process, which mainly uses smelting and casting to obtain solid (hollow) ingot raw materials. After the cooled ingot is cut off the riser and sawed, it is processed into a flange forging blank, and then the forging blank is heated. The solid ingot still needs overall forging, punching, vertical shaft hole expansion, and flat rolling for shaping to manufacture the flange. Although the hollow ingot does not require punching, it still requires sawing of the casting blank, heating of the casting blank, overall forging, vertical shaft hole expansion, and flat rolling for shaping to manufacture the flange. However, no matter which of the above processes, they all have a long process flow, require processes such as forging and punching, and have a huge investment in equipment funds.

[0003] Therefore, in recent years, a short-process casting and rolling composite forming technology for ring parts has been proposed. Based on directly rolling the annular casting blank obtained by sand casting or centrifugal casting after heating, it eliminates the processes of blooming, forging, and punching, and only requires one heating, having prominent advantages such as a short process flow, energy conservation, and material saving (more than 30% material saving and more than 60% energy conservation). It is an inevitable requirement for the large-scale, high-efficiency, high-performance, and green manufacturing of medium-sized high-pressure flanges in the current domestic fields of wind power flanges, petrochemical containers, and aerospace. However, at present, the annular casting blanks obtained by the centrifugal casting process in China are all long casting blanks. When processing flanges, metering cutting is required, and there is no mature technology for thermal cutting in China at present. It is necessary to saw the casting blank after it is completely cooled. On the one hand, the waiting time is relatively long, reducing the production efficiency. On the other hand, it leads to the inability to efficiently and comprehensively utilize the waste heat of the casting blank, increasing the processing heat consumption and being unfavorable to environmentally friendly production. Moreover, since the current domestic and foreign hot rolling expansion equipment is mainly applied to the rolling expansion forming of ring blanks, it can quickly complete the hole expansion operation under certain blank thickness conditions, but there are deficiencies such as a small forging ratio and a slow forging speed for the longitudinal forging of casting blanks. Therefore, the mainstream domestic casting and forging composite forming processes all need to add a forging process link, first perform longitudinal (thick) forging on the ring blank, and then perform hole expansion forming when reaching the rolling expansion thickness. Due to the addition of the forging process, there is a processing time difference for the forgings in the forging and ring rolling processes, and it is difficult to form an automated production rhythm, so most flange processing production lines are difficult to achieve automated production. Summary of the Invention

[0004] The object of the present invention is to solve the above technical problems, and to provide a method and a preparation system for preparing high-pressure flanges, which can prepare high-pressure flanges with non-dendritic, fine densification, homogeneous, spherical microstructures, especially medium-sized high-pressure flanges. For thin-walled ring castings, subsequent processes can be carried out without complete cooling, and the waiting time is greatly shortened, so as to improve production efficiency. Moreover, due to the residual heat of the thin-walled ring castings, it can be comprehensively utilized by the external residual heat utilization system, reducing the processing heat consumption. And because there is no forging process, the production efficiency can be guaranteed without affecting the production rhythm of the assembly line.

[0005] To achieve the above object, the present invention provides the following solution: The present invention discloses a method for preparing a high-pressure flange, including the following steps:

[0006] S1. Centrifugally cast a thin-walled ring casting with a thickness ≤ twice the thickness of the formed flange;

[0007] S2. Cool the thin-walled ring casting to complete crystallization at the corresponding crystallization temperature of the material;

[0008] S3. Heat up the thin-walled ring casting at the crystallization temperature to achieve secondary remelting and obtain a semi-solid ring blank;

[0009] S4. Rotationally roll the semi-solid ring blank by a flattening machine to obtain a flattened blank with a thickness meeting the thickness requirement for vertical ring rolling and hole expanding;

[0010] S5. Perform semi-solid ring rolling forming on the flattened blank by a vertical ring rolling machine to obtain an expanded blank meeting the outer diameter parameter requirements of the flange product;

[0011] S6. Perform rolling expansion and thixotropic forming on the expanded blank by a flat rolling machine to obtain a flange forging blank with a thickness, shape, and flatness meeting the processing requirements of the flange forging;

[0012] S7. Perform temperature-controlled heat treatment on the flange forging blank to finally prepare a high-pressure flange forging.

[0013] Preferably, in step S1, the steelmaking furnace charge and the leftover materials of the same material as the steelmaking furnace charge are fed into an intermediate frequency melting furnace, and elemental alloys are added for conditioning according to the material requirements. The furnace charge is melted into a metal liquid at a preset melting temperature. After reaching the preset holding time, a slag remover is poured in for slag removal. Then, the metal liquid after slag removal is poured into an argon blowing refining holding furnace at a temperature at the preset refining temperature for argon blowing refining. The metal liquid after argon blowing refining is injected into the horizontal ring mold of a centrifugal casting machine, and under the action of the centrifugal force generated by high-speed rotation, it fills the mold and cools into the thin-walled ring casting.

[0014] Preferably, in step S2, the thin-ring casting is taken out from the horizontal annular mold of the centrifugal casting machine and sent into a cooling conveyor device to control the cooling rate, so that when the surface temperature of the thin-ring casting reaches the crystallization temperature required by the material, the crystallization of the casting is completed.

[0015] Preferably, in step S3, the thin-ring casting after controlled-temperature crystallization is sent into a heating furnace to be heated, so that the thin-ring casting is remelted for the second time and kept at the melting temperature to obtain a semi-solid annular blank with a delicate, homogeneous and spherical microstructure.

[0016] Preferably, in step S4, the semi-solid annular blank at the preset flattening temperature is sent to a flattening machine for repeated rolling. Through the rotation and rolling of the rolling head, a large plastic deformation with a large deformation amount is generated from the inside to the outside of the semi-solid annular blank to obtain a flattened blank. The inner hole of the flattened blank remains unchanged, the outer diameter becomes larger, and the thickness of the blank meets the thickness requirements for vertical ring rolling and hole expanding processing.

[0017] Preferably, in step S5, the flattened blank at the preset ring rolling temperature is sent into a vertical ring rolling machine for ring rolling and hole expanding. The driving roller in the vertical ring rolling machine drives the flattened blank to rotate, and under the radial rolling pressure of the driving roller and the core roller, the wall thickness of the flattened blank is reduced as it rotates, thereby controlling the diameter of the flattened blank. During the ring rolling process, the grains of the blank are further refined and homogenized to obtain an expanded blank.

[0018] Preferably, in step S6, the expanded blank at the preset flat rolling temperature is sent into a flat rolling machine. Under the control of the outer mold of the flat rolling machine, the rolling head of the flat rolling machine adjusts the flatness and performs fine forming on the expanded blank to obtain a flange forging blank, and the thickness, shape and flatness of the flange forging blank all meet the processing requirements of the flange forging blank.

[0019] Preferably, in step S7, the flange forging blank with the forming temperature maintained at the preset heat treatment temperature is sent into a heat preservation and heat treatment device, and temperature-controlled heat treatment is carried out under the condition of dual-temperature control. The residual heat in the heat treatment process of the casting is finally used to prepare a high-pressure flange forging.

[0020] A high-pressure flange preparation system is also disclosed, which includes a loading trolley, a centrifugal casting unit, a cooling and conveying device, a crystallized casting automatic handling device, a heating furnace, a semi-solid ring blank conveying device, a semi-solid ring blank automatic handling device, a flattening machine, a flattened blank automatic conveying device, a vertical ring rolling machine, a gantry vertical forging automatic handling device, an expanding blank automatic conveying device, an expanded forging blank automatic handling device, a flat rolling machine, a flange forging automatic transfer device, a flange forging automatic handling device, a flange forging rail flatbed, and a heat preservation and heat treatment chamber, which are arranged in sequence along the production process. The centrifugal casting unit includes an intermediate frequency melting furnace, a molten steel transfer device, an argon blowing refining and heat preservation furnace, and a centrifugal casting machine, which are arranged in sequence along the production process. The centrifugal casting machine is equipped with an automatic metering casting device, an automatic end cover unloading device, an automatic part taking device, an automatic cleaning device, an automatic spraying device, and an automatic end cover loading device.

[0021] Preferably, it includes a waste heat utilization and recovery system, which utilizes the waste heat of the loading trolley, the cooling and conveying device, and the heat preservation and heat treatment chamber through the waste heat utilization and recovery system.

[0022] The present invention has achieved the following technical effects compared with the prior art:

[0023] In the high-pressure flange preparation method and its preparation system of the present invention, a high-pressure flange with a non-dendritic, finely densified, homogeneous, and spherical microstructure can be prepared, especially a medium-sized high-pressure flange. The thin-walled ring casting can undergo subsequent processes without complete cooling, significantly shortening the waiting time to improve production efficiency. Moreover, due to the waste heat of the thin-walled ring casting, it can be comprehensively utilized by the external waste heat utilization system, reducing processing heat consumption. And because there is no forging process link, it will not affect the flow operation rhythm and ensure production efficiency. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a schematic diagram of the overall structure of the high-pressure flange preparation system in the embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of a partial structure of the high-pressure flange preparation process in the embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of a partial structure of the high-pressure flange preparation process in the embodiment of the present invention;

[0028] Figure 4 It is a partial three - structure schematic diagram of the high - pressure flange preparation process in the embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the high - pressure flange preparation process in the embodiment of the present invention.

[0030] Explanation of reference numerals: 1. Loading trolley; 2. Medium - frequency melting furnace; 3. Molten steel transfer device; 4. Argon - blowing refining and heat - preservation furnace; 5. Centrifugal casting machine; 6. Cooling and conveying device; 7. Automatic handling device for crystalline castings; 8. Heating furnace; 9. Semi - solid ring blank conveying device; 10. Automatic handling device for semi - solid ring blanks; 11. Flattening machine; 12. Automatic conveying device for flattened blanks; 13. Vertical ring - rolling machine; 14. Automatic handling device for gantry - type vertical ring - rolled forgings; 15. Automatic conveying device for expanded - hole blanks; 16. Automatic handling device for expanded - hole forged blanks; 17. Horizontal flattening machine; 18. Automatic transfer device for flange forgings; 19. Automatic handling device for flange forgings; 20. Rail flatcar for flange forgings; 21. First heat - preservation and heat - treatment bin; 22. Second heat - preservation and heat - treatment bin; 23. Automatic quantitative casting device; 24. Automatic end - cover unloading device; 25. Automatic part - taking device; 26. Automatic cleaning device; 27. Automatic spraying device; 28. Automatic end - cover loading device; 29. Steel slag ladle; 30. Hydraulic jacking device; 31. Waste heat utilization and recovery system; 32. Storage area for homogeneous scraps; 33. Storage area for steel - making furnace materials; 34. Storage area for elemental alloys. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] Embodiment 1

[0033] This embodiment provides a method for preparing a high - pressure flange. As Figures 1 to 5 shown, it includes the following steps:

[0034] S1. Centrifugally cast a thin - walled ring casting with a thickness ≤ twice the thickness of the formed flange;

[0035] S2. Cool the thin - walled ring casting to complete crystallization at the corresponding crystallization temperature of the material;

[0036] S3. Heat up the thin - walled ring casting at the crystallization temperature to achieve secondary remelting, so as to obtain a semi - solid ring blank with uniform and fine spherical microstructures;

[0037] S4. Feed the semi-solid ring blank to the flattening machine 11 for rotary rolling to obtain a flattened blank with a thickness meeting the thickness requirement for vertical ring rolling and hole expansion.

[0038] S5. Feed the flattened blank into the vertical ring rolling machine 13 and perform semi-solid ring rolling forming to obtain an expanded blank meeting the requirements of the outer diameter parameters of the flange product.

[0039] S6. Feed the expanded blank into the flat rolling machine 17 and perform rolling expansion thixoforming on the expanded blank to obtain a flange forging blank with thickness, shape, and flatness all meeting the processing requirements of the flange forging blank.

[0040] S7. Perform temperature-controlled heat treatment on the flange forging blank to finally prepare a high-pressure flange forging.

[0041] This high-pressure flange preparation method can prepare high-pressure flanges with non-dendritic, fine densification, homogeneous, and spherical microstructures, especially medium-sized high-pressure flanges. The thin-walled ring casting can undergo subsequent processes without complete cooling, significantly shortening the waiting time and improving production efficiency. On the other hand, since the casting blank here has residual heat, it can be comprehensively utilized by the external residual heat utilization system to reduce processing heat consumption. Moreover, this high-pressure flange preparation method does not require additional forging processes, so it will not affect the flow operation rhythm and ensure production efficiency, thus having the advantages of high efficiency, high material yield, low energy consumption, low cost, and high performance.

[0042] In one embodiment, as Figures 1 to 5 shown, in step S1, feed the steelmaking furnace charge and the scrap into the intermediate frequency melting furnace 2. The scrap and the steelmaking furnace charge need to be of the same material, and elemental alloys are added according to the material requirements for conditioning. The furnace charge is melted into a metal liquid at the preset melting temperature. After reaching the preset holding time, slag remover is poured in for slag removal. Then, the metal liquid after slag removal is poured into the argon blowing refining holding furnace 4 at a temperature at the preset refining temperature for argon blowing refining. The metal liquid after argon blowing refining is injected into the horizontal ring mold of the centrifugal casting machine 5. Under the action of the centrifugal force generated by high-speed rotation, it fills the mold and cools into the thin-walled ring casting. Taking the A105# steel high-pressure flange as an example, the preset melting temperature is 1650°C, the preset holding time for refining is 3 - 5 minutes, and the preset refining temperature is 1600 - 1620°C. The molten steel after argon blowing refining is injected into the horizontal ring mold of the centrifugal casting machine 5.

[0043] In one embodiment, as Figures 1 to 5 shown, in step S2, take out the thin-walled ring casting from the horizontal ring mold of the centrifugal casting machine 5 and feed it into the temperature reduction conveying device 6 to control the temperature reduction speed so that the surface temperature of the thin-walled ring casting reaches the crystallization temperature required by the material to complete the crystallization of the casting. Taking the A105# steel high-pressure flange as an example, when the crystallization temperature required by the material is 500 - 550°C, the crystallization of the casting is completed.

[0044] In one embodiment, as Figures 1 to 5 shown, in step S3, the thin-walled ring casting after controlled-temperature crystallization is sent into a heating furnace 8 for heating to remelt the thin-walled ring casting, and heat preservation is carried out at the melting temperature to obtain a semi-solid annular blank with a delicate, homogeneous, and spherical microstructure. Taking the A105# steel high-pressure flange as an example, the thin-walled ring casting is heat-preserved at a melting temperature of 1100 - 1250°C for 15 - 20 min.

[0045] In one embodiment, as Figures 1 to 5 shown, in step S4,

[0046] the semi-solid annular blank at the preset flattening temperature is sent to a flattening machine 11 for repeated rolling. Through the rotation and rolling of the rolling head, plastic deformation with a large deformation amount is generated in the semi-solid annular blank from the inside to the outside to obtain a flattened blank. The inner hole of the flattened blank remains basically unchanged, the outer diameter becomes larger, and the thickness of the blank meets the thickness requirements for vertical ring rolling and hole expanding processing. Taking the A105# steel high-pressure flange as an example, the preset flattening temperature is 1050°C - 1200°C. The flattening machine 11 is preferably a numerically controlled double-head flattening machine.

[0047] In one embodiment, as Figures 1 to 5 shown, in step S5, the flattened blank at the preset ring rolling temperature is sent into a vertical ring rolling machine 13 for ring rolling and hole expanding. The driving roller in the vertical ring rolling machine 13 drives the flattened blank to rotate, and under the radial rolling pressure of the driving roller and the core roller, the flattened blank thins the wall thickness as it rotates, thereby controlling the diameter of the flattened blank. During the ring rolling process, the grains of the blank are further refined and homogenized to obtain an expanded hole blank. Taking the A105# steel high-pressure flange as an example, the preset ring rolling temperature is a temperature not lower than 950 - 1150°C. The vertical ring rolling machine 13 is preferably a numerically controlled vertical ring rolling machine.

[0048] In one embodiment, as Figures 1 to 5 shown, in step S6, the expanded hole blank at the preset flat rolling temperature is sent into a flat rolling machine 17. Under the control of the outer die of the flat rolling machine 17, the rolling head of the flat rolling machine 17 adjusts the flatness and performs fine forming on the expanded hole blank to obtain a flange forging blank. The thickness, shape, and flatness of the flange forging blank all meet the processing requirements of the flange forging blank. The preset flat rolling temperature is a temperature not lower than 900 - 1100°C.. The flat rolling machine 17 is preferably a numerically controlled flat rolling machine.

[0049] In one embodiment, as Figures 1 to 5As shown in the figure, in step S7, the flange forging blank with the forming temperature maintained at the preset heat treatment temperature is fed into the heat preservation heat treatment device, and temperature-controlled heat treatment is carried out under the condition of dual-temperature control. The residual heat in the casting heat treatment process is utilized to finally prepare a high-pressure flange forging. Taking the A105# steel high-pressure flange as an example, the preset heat treatment temperature is 800-1000 °C, and the dual-temperature control is carried out under the condition of (550-450) °C / 1h + (200-120) °C / 0.5h for temperature-controlled heat treatment. The residual heat in the casting heat treatment process is utilized to finally prepare a high-pressure flange forging. Preferably, the heat preservation heat treatment device can adopt a heat preservation heat treatment bin, and multiple heat preservation heat treatment bins can be set in sequence according to the quantity. For example, two are set: the first heat preservation heat treatment bin 21 and the second heat preservation heat treatment bin 22. The temperature of the first heat preservation heat treatment bin 21 is controlled at 550-450 °C, and the heat preservation time is 1h. The temperature of the second heat preservation heat treatment bin 22 is controlled at 200-120 °C, and the heat preservation time is 0.5h.

[0050] The above content only takes the A105# steel high-pressure flange as an implementation case of this high-pressure flange preparation method, and does not limit the protection scope of the present invention thereby. For medium-sized high-pressure flanges of other materials with DN200-DN500, including but not limited to flange forgings such as stainless steel, high alloy steel, low alloy steel, and high-performance steel, only corresponding process parameters need to be matched when applying this process, and they are all included in the protection scope of the present invention by the same token.

[0051] Example 2

[0052] This embodiment provides a high-pressure flange preparation system, as Figures 1 to 5 shown, which can be applied to the high-pressure flange preparation method in Example 1. It includes a loading trolley 1, a centrifugal casting unit, a cooling and conveying device 6, a crystallization casting automatic handling device 7, a heating furnace 8, a semi-solid ring blank conveying device 9, a semi-solid ring blank automatic handling device 10, a flattening machine 11, a flattened blank automatic conveying device 12, a vertical ring rolling machine 13, a gantry vertical rolling forging automatic handling device 14, an expanding blank automatic conveying device 15, an expanding forging blank automatic handling device 16, a flat rolling machine 17, a flange forging automatic transfer device 18, a flange forging automatic handling device 19, a flange forging rail flat car 20, and a heat preservation heat treatment bin, which are arranged in sequence along the production process. The centrifugal casting unit includes an intermediate frequency melting furnace 2, a molten steel transfer device 3, an argon blowing refining and heat preservation furnace 4, and a centrifugal casting machine 5 arranged in sequence along the production process. The centrifugal casting machine 5 is equipped with an automatic quantitative casting device 23, an automatic end cover unloading device 24, an automatic part taking device 25, an automatic cleaning device 26, an automatic spraying device 27, and an automatic end cover loading device 28.

[0053] Preferably, the flattening machine 11 can be a numerically controlled double-head flattening machine, the vertical ring rolling machine 13 can be a numerically controlled vertical ring rolling machine, the flat rolling machine 17 can be a numerically controlled flat rolling machine, and the molten steel transfer device 3 can be a molten steel transfer trough.

[0054] Working principle:

[0055] Step 1: The charging trolley 1 transports the steelmaking furnace charge, the homogeneous scraps (of the same material as the steelmaking furnace charge), and the elemental alloy into the intermediate frequency melting furnace 2. The furnace charge is melted into a metal liquid at a melting temperature of 1650 °C, kept warm for 3 - 5 minutes, and a slag remover is poured in for slag removal. The molten metal after slag removal is transported to the argon blowing refining and holding furnace 4 through the molten steel transfer device 3, while the steel slag is sent to the steel slag ladle 29. The argon blowing refining and holding furnace 4 blows argon to refine the molten metal into molten steel at a temperature of 1600 - 1620 °C. The automatic end cover unloading device 24 opens the end cover of the centrifugal casting machine 5, and the automatic quantitative casting device 23 injects the molten steel into the horizontal annular mold of the centrifugal casting machine 5. Under the action of the centrifugal force generated by high-speed rotation, it fills the mold and cools into a thin-walled ring casting. The automatic end cover unloading device 24 opens the end cover of the centrifugal casting machine 5, the automatic cleaning device 26 cleans the thin-walled ring casting, the automatic spraying device 27 sprays the thin-walled ring casting, and the automatic end cover loading device 28 closes the end cover of the centrifugal casting machine 5;

[0056] Step 2: The automatic part picking device 25 takes out the thin-walled ring casting and sends it into the cooling conveyor device 6 to control the cooling rate. When the surface temperature of the thin-walled ring casting reaches 500 - 550 °C, the casting crystallization is completed;

[0057] Step 3: The crystallization casting automatic handling device 7 transports the thin-walled ring casting at the output end of the cooling conveyor device 6 to the heating furnace 8 and pushes it into the heating furnace 8 under the action of the hydraulic jacking device 30 of the heating furnace 8. The thin-walled ring casting is heated at a melting temperature of 1100 - 1250 °C and kept warm for 15 - 20 minutes to obtain a semi-solid annular blank with a delicate, homogeneous, and spherical microstructure;

[0058] Step 4: The hydraulic jacking device 30 pushes the semi-solid annular blank out of the heating furnace 8 and transports it to the next process through the semi-solid annular blank conveyor device 9. The semi-solid annular blank automatic handling device 10 transports the semi-solid annular blank at the output end of the semi-solid annular blank conveyor device 9, which is at a temperature of 1050 °C - 1200 °C, to the flattening machine 11 for repeated rolling. Through the rotation of the rolling head for rolling, the semi-solid annular blank undergoes plastic deformation with a large deformation amount from the inside to the outside, obtaining a flattened blank. The inner hole of the flattened blank remains basically unchanged, the outer diameter becomes larger, and the thickness of the blank meets the thickness requirements for vertical ring rolling and hole expansion processing;

[0059] In Step 5: The flattened blank automatic conveying device 12 feeds the flattened blank with a temperature of not less than 950 - 1150 °C from the flattening machine 11 into the vertical ring rolling machine 13 for ring expansion and hole expansion. The driving roller in the vertical ring rolling machine 13 drives the flattened blank to rotate. Under the radial rolling pressure of the driving roller and the core roller, the wall thickness of the flattened blank is reduced as it rotates, thereby controlling the diameter of the flattened blank. During the ring expansion process, the grains of the blank are further refined and homogenized to obtain an expanded-hole blank.

[0060] In Step 6: The gantry vertical forging automatic handling device 14 transports the expanded-hole blank to the expanded-hole blank automatic conveying device 15. Then, the expanded-hole forging blank automatic handling device 16 feeds the expanded-hole blank with a temperature of not less than 900 - 1100 °C at the output end of the expanded-hole blank automatic conveying device 15 into the flat rolling machine 17. Under the control of the outer die of the flat rolling machine, the rolling head of the flat rolling machine 17 adjusts the flatness and performs fine forming on the expanded-hole blank to obtain a flange forging blank, and the thickness, shape, and flatness of the flange forging blank all meet the processing requirements of the flange forging blank.

[0061] In Step 7: The flange forging automatic handling device 19 transfers the expanded-hole blank of the flat rolling machine 17 to the flange forging rail flatbed 20. Then, the flange forging rail flatbed 20 feeds the flange forging blank with a forming temperature maintained at 800 - 1000 °C into the heat preservation and heat treatment chamber. Temperature control heat treatment is carried out under the double-temperature condition of (550 - 450) °C / 1h + (200 - 120) °C / 0.5h. The residual heat during the heat treatment process of the casting is utilized, and finally, a high-pressure flange forging is prepared.

[0062] In one embodiment, as Figures 1 to 5 shown, multiple heat preservation and heat treatment chambers can be set up in sequence according to the quantity. For example, two are set up: the No. 1 heat preservation and heat treatment chamber 21 and the No. 2 heat preservation and heat treatment chamber 22. The No. 1 heat preservation and heat treatment chamber 21 controls the temperature at 550 - 450 °C for 1 hour, and the No. 2 heat preservation and heat treatment chamber 22 controls the temperature at 200 - 120 °C for 0.5 hour, and then outputs the high-pressure flange forging.

[0063] In one embodiment, as Figures 1 to 5 shown, the high-pressure flange preparation system includes a homogeneous scrap storage area 32, a steelmaking furnace charge storage area 33, and a single-element alloy storage area 34. The charging trolley 1 obtains homogeneous scrap, steelmaking furnace charge, and single-element alloy through the homogeneous scrap storage area 32, the steelmaking furnace charge storage area 33, and the single-element alloy storage area 34.

[0064] In one embodiment, as Figures 1 to 5 shown, it includes a waste heat utilization and recovery system 31. The waste heat of the charging trolley 1, the cooling and conveying device 6, and the heat preservation and heat treatment chamber (such as: the No. 1 heat preservation and heat treatment chamber 21 and the No. 2 heat preservation and heat treatment chamber 22) is utilized through the waste heat utilization and recovery system 31. The waste heat utilization and recovery system 31 can refer to the existing waste heat system.

[0065] This high-pressure flange preparation system can be widely applied to the production of high-pressure flanges, especially medium-sized high-pressure flanges.

[0066] It has the following advantages:

[0067] 1. The centrifugal casting technology adopted by this high-pressure flange preparation system can accurately measure the molten metal, achieve one blank for one product, and directly process and produce without cutting. The material utilization rate can reach over 98%. At the same time, the perforated casting blank obtained by centrifugal casting has higher density and fewer defects such as slag inclusions, pores, and porosity compared with round (square) ingots or cut materials of medium-thick plates. The centrifugal casting blank has an inner hole by itself, eliminating the need for punching holes, simplifying the forging production process, and reducing the processing difficulty. Moreover, the centrifugal casting machine 5 is equipped with an automatic quantitative pouring device 23, an automatic end cover removing device 24, an automatic part taking device 25, an automatic cleaning device 26, an automatic spraying device 27, and an automatic end cover installing device 28. It is a multi-station disk-type coated metal mold centrifugal casting machine, which can accurately obtain the centrifugal casting blank according to the blank weight of the flange product by controlling the wall thickness of the centrifugal casting blank, and there is no metal consumption in the gating system and riser system.

[0068] 2. This high-pressure flange preparation system first adopts the casting temperature-controlled crystallization technology, that is, the centrifugal casting with a residual heat of 750 - 800 °C is sent to the temperature-controlled crystallization device (i.e., the cooling conveyor device 6). Under the condition of artificially controlling the cooling rate and time, the casting can still maintain a residual heat of 500 - 550 °C after the organizational structure crystallization is completed. The casting with residual heat is reheated and remelted to realize the efficient comprehensive utilization of the residual heat in the casting process, greatly shortening the heating time of the casting, reducing the heating energy consumption of the forging, improving the production efficiency, and reducing the production cost.

[0069] 3. This high-pressure flange preparation system adopts the rough rolling and flattening process. The bottom rotating disk of the rolling machine 11 is a positive circular concave shallow core convex structure. After the casting blank is placed, the shallow core convex part just fits into the middle hole of the casting blank. Under the action of the driving force of the conical rolling head, the bottom rotating disk and the casting blank are driven to rotate horizontally at the same speed, realizing the bilinear composite rolling in the axial direction of the casting blank. It can replace the forging equipment to realize the upsetting processing of the casting blank. When the ring material fills the vertical wall of the outer diameter of the rotating disk under the action of rolling deformation, the ring changes from being subjected to two-way compressive stress to being subjected to three-way compressive stress, effectively improving the internal organizational structure of the casting and enhancing the mechanical properties of the forging.

[0070] 4. This high-pressure flange preparation system first adds a flattening and finishing process at the rear end of the vertical ring hole expanding process, that is, the flange part completed by the vertical ring hole expanding is sent into the flat rolling machine 17 again. Under the condition of controlling the outer diameter, the flat rolling head is used to finely process the thickness, shape, and flatness of the flange forging. While strictly controlling the flange thickness, all machining allowances are rolled to the inner hole, enabling it to have a near-net-shaped machining accuracy.

[0071] 5. This high-pressure flange preparation system first adopts the double-temperature heat treatment technology for flange waste heat. By placing the processed flange forgings into a double-temperature heat treatment device (such as: the first heat preservation heat treatment chamber 21 and the second heat preservation heat treatment chamber 22), through heat preservation heat treatment at different temperature sections and different times, the material of the flange parts becomes more homogeneous and delicate, with stronger processability, and effectively eliminates the internal stress generated during the processing of the flange parts, obtaining flange forgings with better quality and performance.

[0072] The above content only takes the A105# steel high-pressure flange as an implementation case of this high-pressure flange preparation system, and does not limit the protection scope of the present invention thereby. For medium-sized high-pressure flanges of other materials with DN200 - DN500, including but not limited to flange castings and forgings such as stainless steel, high-alloy steel, low-alloy steel, and high-performance steel, applying this process only requires matching corresponding process parameters, and all are similarly included in the protection scope of the present invention.

[0073] Specific examples are used in the present invention to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a high-pressure flange, characterized in that: The following steps are involved: S1. Thin ring castings with centrifugal casting thickness ≤ twice the thickness of the forming flange; S2, cooling the thin ring casting to complete crystallization at the corresponding crystallization temperature of the material; S3, heating the thin ring casting at the crystallization temperature to achieve secondary remelting to obtain a semi-solid ring blank; S4, rotating and rolling the semi-solid annular blank by a rolling machine to obtain a rolled blank having a thickness that meets the thickness requirement of vertical ring rolling and hole expansion; S5, performing semi-solid ring rolling forming on the flattened blank by a vertical ring rolling machine to obtain a hole-expanding blank that meets the outer diameter parameter requirements of the flange product; S6, rolling and thixoforming the expanded hole blank by a flat rolling machine to obtain a flange forging blank whose thickness, shape and flatness all meet the flange forging blank processing requirements; S7, performing temperature-controlled heat treatment on the flange forging blank to finally prepare a high-pressure flange forging.

2. A method for preparing a high-pressure flange according to claim 1, characterized in that: In step S1, steelmaking charge and scraps of the same material as the steelmaking charge are fed into a medium frequency melting furnace, and single-element alloys are added for tempering according to material requirements. The charge is melted into a metal liquid at a preset melting temperature. After a preset insulation time, a slag remover is poured into the slag remover. Then, the slag-removed liquid metal is poured into an argon blowing refining insulation furnace when the temperature is at a preset refining temperature for argon blowing refining. The argon-refined liquid metal is injected into a horizontal annular mold of a centrifugal casting machine, and under the action of the centrifugal force generated by high-speed rotation, the mold is filled and cooled to form the thin ring casting.

3. A method for preparing a high-pressure flange according to claim 2, characterized in that: In step S2, the thin ring casting is taken out from the horizontal ring casting mold of the centrifugal casting machine, and is sent to a cooling conveying device to control the cooling speed so that the surface temperature of the thin ring casting reaches the required crystallization temperature of the material to complete the casting crystallization.

4. A method for preparing a high-pressure flange according to claim 3, characterized in that: In step S3, the thin ring casting after temperature-controlled crystallization is sent to a heating furnace for heating, so that the thin ring casting is remelted for a second time and kept warm at the melting temperature to obtain a semi-solid ring billet with a fine, homogeneous, spherical microstructure.

5. A method for preparing a high-pressure flange according to claim 4, characterized in that: In step S4, the semi-solid ring blank at the preset flattening temperature is sent to a flattening machine for repeated rolling. The semi-solid ring blank undergoes a large amount of plastic deformation from the inside to the outside through rotating rolling of the rolling head to obtain a flattened blank. The inner hole of the flattened blank remains unchanged, the outer diameter becomes larger, and the blank thickness meets the thickness requirements of the vertical ring rolling and hole expansion processing.

6. A method for preparing a high-pressure flange according to claim 5, characterized in that: In step S5, the flattened blank at the preset ring rolling temperature is fed into the vertical ring rolling machine for rolling and expanding. The driving roller in the vertical ring rolling machine drives the flattened blank to rotate, and under the radial rolling action of the driving roller and the core roller, the wall thickness of the flattened blank is reduced as it rotates, thereby controlling the diameter of the flattened blank. During the rolling and expanding process, the grains of the blank are further refined and homogenized to obtain an expanded hole blank.

7. A method for preparing a high-pressure flange according to claim 6, characterized in that: In step S6, the expanded blank at the preset flat rolling temperature is fed into the flat rolling machine. Under the control of the outer die of the flat rolling machine, the rolling head of the flat rolling machine adjusts the flatness and finely forms the expanded blank to obtain a flange forging blank. The thickness, shape and flatness of the flange forging blank all meet the flange forging blank processing requirements.

8. A method for preparing a high-pressure flange according to claim 4, characterized in that: In step S7, the flange forging blank whose forming temperature is maintained at the preset heat treatment temperature is sent to the heat preservation heat treatment device, and the temperature-controlled heat treatment is carried out under dual-temperature control, and the residual heat of the casting heat treatment process is used to finally prepare the high-pressure flange forging.

9. A high-pressure flange preparation system, characterized in that: It includes a loading trolley, a centrifugal casting unit, a cooling and conveying device, an automatic handling device for crystallized castings, a heating furnace, a semi-solid ring billet conveying device, an automatic handling device for semi-solid ring billets, a flattening machine, an automatic conveying device for flattened billets, a vertical ring rolling machine, a gantry vertical rolling forging automatic handling device, an automatic conveying device for expanded hole billets, an automatic handling device for expanded hole forging billets, a flattening machine, an automatic transfer device for flange forgings, an automatic handling device for flange forgings, a flange forging rail flat car, and an insulation heat treatment warehouse, which are arranged in sequence along the production process. The centrifugal casting unit includes a medium-frequency melting furnace, a molten steel transfer device, an argon blowing refining and insulation furnace, and a centrifugal casting machine, which are arranged in sequence along the production process. The centrifugal casting machine is equipped with an automatic quantitative casting device, an automatic end cover unloading device, an automatic piece picking device, an automatic cleaning device, an automatic spraying device, and an automatic end cover installation device.

10. A high pressure flange preparation system according to claim 9, characterized in that: It includes a waste heat utilization and recovery system, through which the waste heat of the loading trolley, the cooling conveying device and the thermal insulation heat treatment bin is utilized.

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