Ring rolling method for large flange ring piece for wind power tower

Abstract

The invention belongs to the field of manufacturing of large flange ring pieces in wind power towers, and particularly relates to a ring rolling method for a large flange ring piece for a wind power tower. In the prior art, after a forged large flange ring piece is rolled, the ring piece needs to be moved to a special heat treatment area to be heated and cooled, and the production continuity is damaged. Based on the problems, the ring piece is cooled while the ring is rolled, and for a special large flange ring blank for the wind power tower, the internal organization structure is stable and the mechanical property is excellent when the ring piece leaves the ring rolling procedure by controlling the roller speed, the cooling condition and the rolling starting temperature and the rolling finishing temperature in the ring rolling stage; and the method can be directly used for a subsequent machining process without independent heat treatment.

Description

Technical Field

[0001] The invention belongs to the field of manufacturing large-sized flange rings for wind power towers, and in particular relates to a method for rolling large-sized flange rings for wind power towers. Background Art

[0002] Large flange rings are the main connecting parts in wind turbine towers. As the tower height can reach more than 100m, the flange, as the connecting element of the tower, bears various loads in the air, and the stress conditions are very complicated, so large flange rings are often super thick. For the manufacture of such large-sized rings, the more advanced production process is rolling manufacturing, and its rolling forming process is blanking-heating-forging blanking-heating-ring rolling-heat treatment-rough machining-finishing.

[0003] However, the current heat treatment process requires the ring to be moved to a special heat treatment area, and then rough and fine processing are carried out after heat treatment such as heating and cooling. This is separated from other processes, which not only destroys the continuity of process production and reduces production efficiency, but also wastes resources such as electricity and coal, increases energy consumption per unit of output value, and is not conducive to the development of high-tech manufacturing industries. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for rolling large flange rings for wind power towers, so that the flange rings do not need to be heat treated after the ring rolling process, and can meet the process requirements and directly enter the subsequent machining process (rough processing and fine processing).

[0005] A method for rolling a large flange ring for a wind power tower according to the present invention comprises the following steps:

[0006] The forged ring blank enters the ring rolling process, which includes the biting stage, the ring rolling stage and the rounding stage. After the ring is placed in the ring rolling mechanism and successfully bitten, it enters the ring rolling stage, and the surface of the ring is cooled while the ring is rolling.

[0007] In the ring rolling stage, the core roller pressing rate is 0.44-2.35 mm / s, the cone roller pressing rate is 0.8 of the core roller pressing rate, and the driving roller rotation rate is 8-20 r / min;

[0008] The cooling rate in the ring rolling stage is 15℃ / s~100℃ / s, and the cooling range width is 200~900mm; the cooling range width refers to the chord length between any two points on the inner circumference or outer circumference of the ring. The cooling medium covers the axial height of the ring, and the inner and outer cooling units cool the inner and outer walls of the ring at the same time respectively; the cooling makes the deformation in the rolling process penetrate to the core of the axial section of the ring;

[0009] The ring temperature is 1100-1200°C at the beginning of the ring rolling stage and 700-850°C at the end of the ring rolling stage;

[0010] At the beginning of ring rolling, the ring thickness (the difference between the inner and outer radii) is 120-750mm, and the outer diameter is 800-5500mm;

[0011] After the ring rolling stage, cooling is stopped, and after the rounding stage, the rolled parts that can be directly used for machining are obtained.

[0012] The present invention cools the surface of the ring while rolling the ring, so that the surface temperature of the ring is reduced, and the temperature difference between the core and the surface of the axial section is greatly increased. During the rolling process, the deformation resistance of the surface matrix with a lower temperature is larger, and the deformation amount is reduced and it is not easy to deform. However, the center temperature of the axial section is high and it is easy to deform. According to the principle of constant volume, the volume of the pressed metal will be transferred to the core of the ring, so that the deformation penetrates into the core of the axial section of the ring, and the deformation penetrates into the core of the axial section. The present invention is aimed at large flange ring blanks for special wind power towers. By controlling the rolling roller speed, cooling conditions, and the starting and final rolling temperatures of the ring rolling stage, the internal organizational structure of the ring is stable when it leaves the ring rolling process, and the mechanical properties are excellent. It not only improves the comprehensive performance of the ring, but also saves the subsequent heat treatment process. After the ring rolling process, it directly enters the machining process, reducing the production cost of large flange rings.

[0013] The ring rolling method of the present invention is applicable to flange steel specified in JB / T 11218-2020 standard, preferably Q355NE flange steel.

[0014] By adopting the ring rolling method of the present invention, without subsequent heat treatment, the average yield strength in each direction is ≥350MPa, the average tensile strength in each direction is ≥520MPa, the elongation is ≥25%, and the average room-temperature impact energy KV2 in each direction is ≥170J, with excellent performance; the surface and core of the rolled part are both pearlite + ferrite structures, the grain size is ≥7.5 and there is no mixed crystal phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the metallographic structure diagram of the rolled piece in Example 1.

[0016] Figure 2 This is the metallographic structure diagram of the rolled piece in Example 2.

[0017] Figure 3 This is the metallographic structure diagram of the rolled piece in Example 3.

[0018] Figure 4 This is the metallographic structure diagram of the rolled piece in Example 4.

[0019] Figure 5This is the metallographic structure diagram of the rolled piece in Example 5.

[0020] Figure 6 This is the metallographic structure diagram of the rolled piece in Comparative Example 2.

[0021] Figure 7 This is the metallographic structure diagram of the rolled piece in Comparative Example 3.

[0022] Figure 8 It is a three-dimensional schematic diagram of the position relationship between the ring and each roller in the ring rolling process.

[0023] Fig. 9 It is a schematic diagram of the top view of the position relationship between the ring, the cooling unit and each roller in the ring rolling stage;

[0024] Among them: 1-driving roller, 2-left guide roller, 3-right guide roller, 4-core roller, 5-cone roller, 6-ring, 7-inner cooling unit, 8-outer cooling unit, 9-cooling unit moving track. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with specific implementation cases and drawings. It should be noted that the specific embodiments described below are only used to explain the present invention, but the present invention is not limited to these embodiments. Those skilled in the art can make equivalent substitutions based on the present invention without departing from the purpose and scope of the technical solution, which should all be covered within the protection scope of the present invention.

[0026] The ring blank used in the ring rolling process of the present invention is a round blank obtained by melting according to the component requirements of Q355NE steel for flange rings, and then the round blank is punched to obtain a ring blank. The rolled piece obtained after rolling is not subjected to heat treatment such as normalizing, and can be directly used for rough processing and fine processing in subsequent machining processes after cooling to room temperature.

[0027] The Q355NE steel used in the present invention contains the chemical components and the mass percentage of each chemical component: C: ≤0.18%, Si: ≤0.50%, Mn: 0.9-1.65%, P: ≤0.012%, S: ≤0.005%, Nb: 0.005-0.05%, V: 0.01-0.12%, Ti: 0.006-0.05%, Cr: ≤0.3%, Ni: ≤0.5%, Cu: ≤0.2%, Mo: ≤0.1%, N: ≤0.015%, Al: ≥0.015%, and the balance is iron and unavoidable impurities.

[0028] The parameters such as yield strength in the embodiments are tested in accordance with JB / T 11218-2020 for wind power tower flange forgings.

[0029] The relationship between the ring and the rollers in the ring rolling process is as follows: Figure 8 shown.

[0030] The position relationship between the ring, cooling unit and rollers during the ring rolling stage is as follows: Fig. 9 As shown, at the beginning of rolling, the driving roller 1 drives the ring 6 to rotate, and the core roller 4 and the cone roller 5 are fed simultaneously. After the biting stage, the ring rolling stage begins, at which time the cooling device is started to align the inner and outer cooling units with the inner and outer surfaces of the ring respectively. After the cooling device is aligned with the ring 6, cooling (water spray cooling) is started, and the cooling water covers the axial height of the ring 6.

[0031] The outer cooling unit 8 is arranged on the outer side of the ring 6, and the inner cooling unit 7 is arranged on the inner side of the ring 6, and there is a gap between the inner cooling unit 7 and the outer cooling unit 8 and the ring 6. Displacement sensors are arranged on the inner and outer cooling units to monitor the movement of the ring 6, and the cooling units are moved on the cooling unit moving track 9 as the ring 6 grows, so that the distance between the outer cooling unit 8 and the inner cooling unit 7 and the surface of the ring 6 is always consistent.

[0032] In the ring rolling stage, the ring 6 rotates with the rolling mechanism and is cooled during the rotation process; the ring 6 is rolled when passing through the radial rolling mechanism (the hole profile of the driving roller 1 and the core roller 4), and then the ring 6 is rolled when passing through the axial rolling mechanism (the hole profile of the tapered roller 5), and then rotates to the cooling unit area to be quickly cooled; the left guide roller 2 and the right guide roller 3 are driven rollers that rotate freely, and play a limiting role to assist the ring forming. After the above process, the entire ring has completed a rolling process. During the ring rolling process, the pressing rate of the core roller 4 and the speed of the driving roller 1 remain unchanged. When the ring 6 has undergone multiple rolling processes, the ring rolling stage ends and the cooling device is turned off; it enters the rounding stage, and after the rounding stage is completed, the rolling mechanism is turned off to obtain the rolled piece after processing.

[0033] Example 1

[0034] Put the forged ring blank into the ring rolling machine, start the ring rolling machine to make the ring bite and start the ring rolling stage with the roller rotation. The ring rolling temperature is 1163℃, the core roller pressing rate is 0.8mm / s, the cone roller pressing rate is 0.64mm / s, and the driving roller speed is 10r / min. The surface of the ring is cooled while rolling the ring. The cooling rate is 90℃ / s and the width of the cooling range is 200mm. The cooling process allows the deformation to penetrate into the core of the axial section of the ring during the rolling process. Stop cooling at the end of the ring rolling stage. The final rolling temperature of the ring is 792℃, and the rounding stage is entered. After the rounding is completed, the rolled piece is obtained, and it is directly put into the subsequent machining process after cooling to room temperature.

[0035] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.147%, Si: 0.24%, Mn: 1.34%, P: 0.010%, S: 0.003%, Nb: 0.04%, V: 0.032%, Ti: 0.029%, Cr: 0.12%, Ni: 0.04%, Cu: 0.03%, Mo: 0.02%, N: 0.0072%, Al: 0.04%, and the balance is iron and unavoidable impurities.

[0036] The thickness of the ring before rolling is 130mm and the outer diameter is 1000mm. The thickness of the ring after rolling is 90mm and the outer diameter is 1640mm.

[0037] The average yield strength of the rolled piece in each direction is 377MPa, the average tensile strength in each direction is 528MPa, the elongation is 28%, and the average room temperature impact energy in each direction is 187J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 1 As shown, the grain size is 8 to 8.5 and there is no mixed crystal phenomenon.

[0038] Example 2

[0039] Put the forged ring blank into the ring rolling machine, start the ring rolling machine to make the ring bite and start the ring rolling stage with the roller rotation. The ring rolling temperature is 1172℃, the core roller pressing rate is 1.2mm / s, the cone roller pressing rate is 0.96mm / s, and the driving roller speed is 16r / min. The surface of the ring is cooled while rolling the ring. The cooling rate is 75℃ / s and the width of the cooling range is 300mm. The cooling process allows the deformation to penetrate into the core of the axial section of the ring during the rolling process. Stop cooling at the end of the ring rolling stage. The final rolling temperature of the ring is 783℃, and the rounding stage is entered. After the rounding is completed, the rolled piece is obtained, and it is directly put into the subsequent machining process after cooling to room temperature.

[0040] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.125%, Si: 0.36%, Mn: 1.12%, P: 0.009%, S: 0.001%, Nb: 0.012%, V: 0.07%, Ti: 0.02%, Cr: 0.1%, Ni: 0.06%, Cu: 0.04%, Mo: 0.06%, N: 0.0094%, Al: 0.03%, and the balance is iron and unavoidable impurities.

[0041] The thickness of the ring before rolling is 230mm and the outer diameter is 1200mm. The thickness of the ring after rolling is 172mm and the outer diameter is 2200mm.

[0042] The average yield strength of the rolled piece in each direction is 371MPa, the average tensile strength in each direction is 530MPa, the elongation is 26%, and the average room temperature impact energy in each direction is 191J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 2 As shown, the grain size is 8 to 8.5 and there is no mixed crystal phenomenon.

[0043] Example 3

[0044] Put the forged ring blank into the ring rolling machine, start the ring rolling machine to make the ring bite and start the ring rolling stage with the roller rotation. The ring rolling temperature is 1157℃, the core roller pressing rate is 0.94mm / s, the cone roller pressing rate is 0.75mm / s, and the driving roller speed is 14r / min. The surface of the ring is cooled while rolling the ring. The cooling rate is 70℃ / s and the width of the cooling range is 400mm. The cooling process allows the deformation to penetrate into the core of the axial section of the ring during the rolling process. Stop cooling at the end of the ring rolling stage. The final rolling temperature of the ring is 779℃, and the rounding stage is entered. After the rounding is completed, the rolled piece is obtained, and it is directly put into the subsequent machining process after cooling to room temperature.

[0045] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.134%, Si: 0.22%, Mn: 1.38%, P: 0.009%, S: 0.003%, Nb: 0.04%, V: 0.03%, Ti: 0.01%, Cr: 0.05%, Ni: 0.2%, Cu: 0.1%, Mo: 0.005%, N: 0.005%, Al: 0.04%, and the balance is iron and unavoidable impurities.

[0046] The thickness of the ring before rolling is 290mm and the outer diameter is 2000mm. The thickness of the ring after rolling is 214mm and the outer diameter is 3800mm.

[0047] The average yield strength in all directions of the rolled piece is 368MPa, the average tensile strength in all directions is 534MPa, the elongation is 27%, and the average room temperature impact energy in all directions is 203J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 3 As shown, the grain size is 7.5 to 8 and there is no mixed crystal phenomenon.

[0048] Example 4

[0049] Put the forged ring blank into the ring rolling machine, start the ring rolling machine to make the ring bite and start the ring rolling stage with the roller rotation. The ring rolling temperature is 1147℃, the core roller pressing rate is 0.98mm / s, the cone roller pressing rate is 0.78mm / s, and the driving roller speed is 18r / min. The surface of the ring is cooled while rolling the ring. The cooling rate is 55℃ / s and the width of the cooling range is 600mm. The cooling process allows the deformation to penetrate into the core of the axial section of the ring during the rolling process. Stop cooling at the end of the ring rolling stage. The final rolling temperature of the ring is 764℃, and the rounding stage is entered. After the rounding is completed, the rolled piece is obtained, and it is directly put into the subsequent machining process after cooling to room temperature.

[0050] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.17%, Si: 0.27%, Mn: 1.43%, P: 0.007%, S: 0.003%, Nb: 0.01%, V: 0.08%, Ti: 0.04%, Cr: 0.14%, Ni: 0.35%, Cu: 0.01%, Mo: 0.02%, N: 0.01%, Al: 0.03%, and the balance is iron and unavoidable impurities.

[0051] The thickness of the ring before rolling is 412mm and the outer diameter is 3889mm. The thickness of the ring after rolling is 325mm and the outer diameter is 7362mm.

[0052] The average yield strength of the rolled piece in each direction is 359MPa, the average tensile strength in each direction is 536MPa, the elongation is 30%, and the average room temperature impact energy in each direction is 194J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 4 As shown, the grain size is 8 to 8.5 and there is no mixed crystal phenomenon.

[0053] Example 5

[0054] Put the forged ring blank into the ring rolling machine, start the ring rolling machine to make the ring bite and start the ring rolling stage with the roller rotation. The ring rolling temperature is 1152℃, the pressing rate of the core roller is 0.88mm / s, the pressing rate of the cone roller is 0.7mm / s, and the driving roller speed is 12r / min. The surface of the ring is cooled while rolling the ring. The cooling rate is 40℃ / s and the width of the cooling range is 800mm. The cooling process allows the deformation to penetrate into the core of the axial section of the ring during the rolling process. Stop cooling at the end of the ring rolling stage. The final rolling temperature of the ring is 725℃, and the rounding stage is entered. After the rounding is completed, the rolled piece is obtained, and it is directly put into the subsequent machining process after cooling to room temperature.

[0055] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.15%, Si: 0.43%, Mn: 1.26%, P: 0.009%, S: 0.002%, Nb: 0.042%, V: 0.10%, Ti: 0.04%, Cr: 0.25%, Ni: 0.37%, Cu: 0.15%, Mo: 0.08%, N: 0.009%, Al: 0.017%, and the balance is iron and unavoidable impurities.

[0056] The thickness of the ring before rolling is 732mm and the outer diameter is 5000mm. The thickness of the ring after rolling is 468mm and the outer diameter is 8500mm.

[0057] The average yield strength of the rolled piece in each direction is 374MPa, the average tensile strength in each direction is 529MPa, the elongation is 26%, and the average room temperature impact energy in each direction is 179J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 5 As shown, the grain size is 7.5 to 8 and there is no mixed crystal phenomenon.

[0058] Comparative Example 1

[0059] The chemical composition of the steel for rings is as follows by mass percentage: C: 0.13%, Si: 0.26%, Mn: 1.11%, P: 0.007%, S: 0.001%, Nb: 0.003%, V: 0.0018%, Ti: 0.001%, Cr: 0.11%, Ni: 0.12%, Cu: 0.01%, Mo: 0.03%, N: 0.001%, Al: 0.002%, and the balance is iron and unavoidable impurities.

[0060] The ring rolling start temperature is 1157° C., and the final rolling temperature is 784° C. Other preparation methods are the same as those in Example 1.

[0061] The average yield strength in all directions of the rolled piece is 314MPa, the average tensile strength in all directions is 437MPa, the elongation is 24%, and the average room temperature impact energy in all directions is 97J. The surface and core structures of the rolled piece are both pearlite + ferrite structures, with a grain size of 7.5 to 8 and no mixed crystal phenomenon.

[0062] Even if the process remains unchanged, the performance of the ring will decrease if the ring composition changes and cannot meet the requirements of the enterprise.

[0063] Comparative Example 2

[0064] The ring rolling start temperature is 1050° C., and the final rolling temperature is 732° C. Other preparation methods are the same as those in Example 1.

[0065] The average yield strength of the rolled piece in each direction is 318MPa, the average tensile strength in each direction is 504MPa, the elongation is 22%, and the average room temperature impact energy in each direction is 144J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 6 As shown, the grain size is 7 to 9, and obvious mixed crystal phenomenon occurs.

[0066] The initial rolling temperature is too low, resulting in insufficient deformation of the ring. Although it can meet the requirements of the enterprise, all performance properties are significantly reduced.

[0067] Comparative Example 3

[0068] The ring rolling temperature is 1161°C and the final rolling temperature is 980°C. The ring is not cooled during the ring rolling stage, but air cooling is still performed during the rolling process, and the ring exchanges heat with the air, causing the temperature to drop. The other preparation methods are the same as those in Example 1.

[0069] The average yield strength of the rolled piece in each direction is 301MPa, the average tensile strength in each direction is 475MPa, the elongation is 24%, and the average room temperature impact energy in each direction is 149J. The surface and core structures of the rolled piece are both pearlite + ferrite structures. Figure 7 As shown, the grain size is 7 to 9, and obvious mixed crystal phenomenon occurs.

[0070] The performance of the rings without cooling is significantly reduced and cannot meet the requirements of the enterprise.

[0071] Comparative Example 4

[0072] The ring rolling temperature was 1160°C, the final rolling temperature was 657°C, and the cooling rate during the ring rolling stage was 140°C / s. The other preparation methods were the same as those in Example 1.

[0073] The average yield strength in all directions of the rolled piece is 322MPa, the average tensile strength in all directions is 489MPa, the elongation is 22%, and the average room temperature impact energy in all directions is 110J. The core structure of the rolled piece is pearlite + ferrite, the grain size is 7.5-8, and a large amount of bainite and a small amount of widmanstattenite appear in the surface structure.

[0074] The excessive cooling rate leads to insufficient deformation of the ring. Although it can meet the requirements of the enterprise, all performances are significantly reduced.

[0075] Comparative Example 5

[0076] The ring rolling temperature was 1147°C, the final rolling temperature was 974°C, no cooling was added during the rolling process, and the rolled piece was normalized before entering the machining process. The normalizing temperature was 850°C, the normalizing time was 150 min, and the other preparation methods were the same as in Example 1.

[0077] After normalizing, the average yield strength in all directions is 372MPa, the average tensile strength in all directions is 524MPa, the elongation is 24%, and the average room temperature impact energy in all directions is 176J. After normalizing, the surface and core structures are both pearlite + ferrite structures, the grain size is 8-8.5, and there is no mixed crystal phenomenon.

[0078] The performance of the rings without cooling but normalizing is similar to that of the rings with cooling but no normalizing, which meets the requirements of enterprises.

Claims

1. A method for rolling a large flange ring for a wind power tower, characterized in that: The following steps are involved: The forged ring enters the ring rolling process, which includes the biting stage, the ring rolling stage and the rounding stage; after the ring is placed in the ring rolling mechanism and successfully bitten, it enters the ring rolling stage. While rolling the ring, the surface of the ring is cooled at a cooling rate of 15℃ / s to 100℃ / s.

2. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: The width of the cooling range is 200 to 900 mm, and the width of the cooling range refers to the chord length between any two points on the inner circumference or outer circumference of the ring.

3. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: The temperature of the ring is 1100-1200°C at the beginning of the ring rolling stage, and the temperature of the ring is 700-850°C at the end of the ring rolling stage.

4. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: At the beginning of the ring rolling stage, the difference between the inner and outer radii of the ring is 120 to 750 mm, and the outer diameter is 800 to 5500 mm.

5. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: The inner wall and the outer wall of the ring are cooled simultaneously by the inner cooling unit and the outer cooling unit respectively, and the cooling makes the deformation during the rolling process penetrate to the core of the axial section of the ring.

6. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: In the ring rolling stage, the pressing rate of the core roller is 0.44-2.35 mm / s, the pressing rate of the cone roller is 0.8 of the pressing rate of the core roller, and the rotation rate of the driving roller is 8-20 r / min.

7. A method for rolling a large flange ring for a wind power tower according to claim 1, characterized in that: After the ring rolling stage, cooling is stopped and after the rounding stage, the rolled parts are obtained directly for machining.

8. The ring rolling method described in any one of claims 1 to 7 is applicable to flange steel specified in JB / T 11218-2020.

9. The ring rolling method described in any one of claims 1 to 7 is applicable to Q355NE flange steel.

10. The Q355NE flange steel as described in claim 9, the elements contained in the steel and the mass percentage of each element are as follows: C: ≤0.18%, Si: ≤0.50%, Mn: 0.9~1.65%, P: ≤0.012%, S: ≤0.005%, Nb: 0.005~0.05%, V: 0.01~0.12%, Ti: 0.006~0.05%, Cr: ≤0.3%, Ni: ≤0.5%, Cu: ≤0.2%, Mo: ≤0.1%, N: ≤0.015%, Al: ≥0.015%, and the balance is iron and unavoidable impurities.

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