Casting forming die, casting and wind generating set

Abstract

The utility model provides a casting forming mold, a casting and a wind generating set, the casting forming mold comprises an outer mold box and an inner mold core located in the outer mold box, and the outer mold box comprises a metal casting mold and a sand covering layer covering the surface of an inner cavity of the metal casting mold; and a casting cavity is formed between the outer mold box and the inner mold core, and molten iron can be poured into the casting cavity and is cooled and molded into an iron casting in the casting cavity. The nodular iron casting obtained according to the embodiment of the utility model has excellent comprehensive performance, and particularly can obviously improve the low-temperature impact energy, ensure the low-temperature strength of the casting and reduce the fracture risk of the casting.

Description

Technical Field

[0001] The utility model relates to the technical field of casting and molding, in particular to a casting molding die, a main shaft of a wind power generator set and a wind power generator set. Background Art

[0002] Large mechanical parts in the prior art, such as the main shaft and base of wind turbines, are usually made by forging steel. However, with the development of large-scale wind turbines, the size of mechanical parts in wind turbines is also getting bigger and bigger, and conventional forging methods can no longer meet production requirements.

[0003] With the continuous development of ductile iron technology, ductile iron has gradually replaced cast steel and become a new type of metal material. As a type of ductile iron, cast ferrite ductile iron has been widely used in engineering machinery, basic parts of injection molding machines, basic parts of die-casting machines, and large mechanical parts or key parts of wind turbines.

[0004] For large-sized mechanical parts, molten iron is usually poured into sand molds for component molding. However, sand casting molds use a large amount of sand, and the sand processing system is large, complex, energy-intensive, and costly. In addition, sand molds cannot be reused, and each casting needs to be reshaped, which makes the sand mold manufacturing process less efficient. Furthermore, due to the low hardness and poor rigidity of the sand mold, it cannot resist the graphitization expansion force generated by the molten iron during the solidification process, and the casting is prone to shrinkage defects. It is impossible to meet the performance requirements of the impact work in a low temperature environment while maintaining the strength requirements, resulting in the casting being prone to fracture at low temperatures. For wind turbines that work in the field for a long time, key mechanical components such as the main shaft and base that do not meet the comprehensive performance requirements are major hidden dangers to the safe operation of wind turbines. Utility Model Content

[0005] The utility model aims to provide a casting molding die, a main shaft of a wind turbine generator set and a wind turbine generator set. The casting molding die is used for casting ductile iron castings, especially the main shaft of the wind turbine generator set, so as to improve the comprehensive performance of the ductile iron castings.

[0006] According to an embodiment of the utility model, a casting forming mold is provided for forming a cast iron part. The casting forming mold includes an outer mold box and an inner core located in the outer mold box. The outer mold box includes a metal casting mold and a sand coating layer covered on the inner cavity surface of the metal casting mold. A casting cavity is formed between the outer mold box and the inner core. Molten iron can be poured into the casting cavity and cooled in the cavity to form a cast iron part.

[0007] According to one aspect of the utility model, the metal casting mold is an iron mold, the thickness of the iron mold is 50mm-200mm, and the thickness of the sand coating layer is 6mm-20mm.

[0008] According to one aspect of the utility model, the outer mold box includes a bottom box, a top box and a middle box arranged between the bottom box and the top box, the middle box is an iron mold covered sand mold box, the top box and the bottom box are sand boxes, and the inner core is a sand core.

[0009] According to one aspect of the present invention, the middle box is divided into multiple sections.

[0010] According to one aspect of the utility model, the casting mold further includes a bottom pouring system, and a runner for conveying molten iron into the mold cavity is provided in the bottom box.

[0011] According to one aspect of the utility model, a riser is provided in the top box, and an exhaust channel is provided in the inner core, and the exhaust channel is communicated with the riser.

[0012] According to one aspect of the utility model, in the height direction of the mold, the outer mold box and / or the inner mold core is divided into multiple sections.

[0013] According to one aspect of the utility model, the casting is the main shaft of a wind turbine generator set, and the main shaft includes a shaft body, a large end flange connected to one end of the shaft body, and a small end flange connected to the other end of the shaft body, and there is also a trumpet-shaped connecting section between the large end flange and the shaft body, the bottom box corresponds to the large end flange, the middle box corresponds to the shaft body and the trumpet-shaped connecting section, and the top box corresponds to the small end flange.

[0014] According to another aspect of the utility model, a casting is provided. The casting is made by using the casting forming mold described above.

[0015] According to another aspect of the utility model, the casting is a main shaft of a wind turbine generator set, and the outer diameter of the main shaft is greater than or equal to 1 m.

[0016] According to another aspect of the utility model, a wind turbine generator set is provided, and the wind turbine generator set comprises the casting described above.

[0017] The core structure of the ductile iron casting obtained by the casting forming mold according to the embodiment of the utility model is good, and there is basically no special-shaped graphite such as broken block graphite. The tensile strength, yield strength, and low-temperature impact energy of the ductile iron can be improved, and the mechanical properties of large-section ductile iron are significantly improved. Therefore, the iron mold covered with sand casting forming mold provided by the utility model is particularly suitable for mass production of key parts such as large-section castings in wind turbines, which can significantly improve the low-temperature impact energy, ensure the low-temperature strength of the parts, reduce the risk of part fracture, and improve the operating safety of wind turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects and features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0019] Figure 1 is a three-dimensional diagram of a fan main shaft according to an embodiment of the utility model;

[0020] Figure 2 is a cross-sectional view of a fan main shaft according to an embodiment of the utility model;

[0021] Figure 3 is a cross-sectional view of a molding die according to an embodiment of the utility model;

[0022] Figure 4 is a cross-sectional view of another example of a molding die according to an embodiment of the utility model;

[0023] Figure 5 It is a schematic diagram of the sand shooting process of the forming mold according to an embodiment of the utility model. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] In addition, unless there are contradictory descriptions, the various embodiments described below can also be combined with each other. In addition, unless otherwise specified, the devices with the same reference numerals in various embodiments have the same structure, and no redundant description is provided.

[0027] According to one aspect of an embodiment of the utility model, a casting molding mold is provided. Different from a traditional sand mold, the utility model embodiment adopts a metal mold-covered sand mold, and the casting molding mold includes a metal mold made of metal and a sand-covered layer covered on the inner surface of the metal mold, and has the advantages of both metal molds and sand molds. As an example, the metal mold can be an iron mold.

[0028] According to an embodiment of the utility model, a casting forming mold comprises an outer mold box and an inner mold core located in the outer mold box, wherein the outer mold box comprises a metal casting mold and a sand coating layer covered on the inner cavity surface of the metal casting mold, a casting cavity is formed between the inner mold core and the sand coating layer, and a casting can be formed after molten iron is poured into the casting cavity and cooled and solidified.

[0029] Below, we will take the main shaft of a wind turbine as an example, and refer to the attached Figures 1 to 5 The casting forming mold according to the embodiment of the utility model is described, however, the casting forming mold of the utility model is also suitable for manufacturing other mechanical parts of wind turbines and large castings in other fields, especially castings with a thickness greater than or equal to 60 mm. Accordingly, the shape and structure of the forming mold, especially the cavity, are changed accordingly according to different mechanical parts, which will not be described here.

[0030] Figure 1 is a three-dimensional diagram of a main shaft 100 of a wind turbine generator set according to an embodiment of the utility model. Figure 2 1 is a cross-sectional view of a main shaft of a wind turbine generator set according to an embodiment of the utility model. The main shaft 100 includes a shaft body 110, a large end flange 120 disposed at one end of the shaft body 110, and a small end flange 130 disposed at the other end of the shaft body 110. The large end flange 120 is used to connect with the hub of the wind turbine generator set, and the small end flange 130 is used to connect with the gearbox of the wind turbine generator set. Due to the large size difference between the shaft body 110 and the large end flange 120, a trumpet-shaped connecting portion 140 is also used to make a transition connection between the shaft body 110 and the large end flange 120.

[0031] Figure 3 FIG. 2 shows a cross-sectional view of a molding die according to an embodiment of the present utility model. Figure 3 As shown, the molding die 200 according to the embodiment of the utility model includes an outer mold box 210 having a hollow inner cavity. The inner surface of the outer mold box 210 has a contour consistent with the outer surface of the spindle 100 and is used to mold the outer contour of the spindle 100 .

[0032] In order to reduce the weight of the main shaft 100 and save manufacturing costs, Figure 2As shown, the spindle 100 is generally formed into a hollow structure. Therefore, the molding die according to the embodiment of the utility model further includes an inner core 220, the outer surface of which is consistent with the contour of the inner cavity surface of the spindle 100, and is used to mold the inner surface of the spindle 100. The inner core 220 can be inserted into the outer mold box 210, and there is a gap between the inner core 220 and the outer mold box 210, so as to form a mold cavity 300 consistent with the shape of the spindle 100 between the two.

[0033] The molding die 200 according to the embodiment of the present invention is a metal mold covered with sand. Figure 3 As shown, the outer mold box 210 includes a metal mold 212 and a sand coating 213 covered on the inner surface of the metal mold 212. The metal mold 212 can be an iron mold. Compared with the traditional sand mold, the casting molding mold according to the embodiment of the utility model has a significant chilling effect in the crystallization process of ductile iron molten iron due to the thin sand coating, which can refine the grain size of the casting and improve the spheroidization rate, and can significantly improve the dimensional accuracy and density of the casting. At the same time, due to the presence of the sand coating 213, the graphite expansion of the ductile iron can be used to self-compensate the casting to obtain high-quality castings.

[0034] According to an embodiment of the utility model, the weight of the main shaft 100 is approximately 10 tons to 20 tons. In the axial direction of the main shaft 100, the thickness of the main shaft is variable, and the main shaft wall thickness ranges from 30mm to 200mm. Correspondingly, the thickness of the iron casting mold is also variable, and the thickness at different positions is different, approximately in the range of 50mm to 200mm. In addition, the thickness of the sand coating 113 is 6mm to 20mm. The thickness of the sand coating affects the quality of the casting and the production cost. If the thickness of the sand coating is too thick, it will not only affect the chilling effect, but also increase the production cost. In addition, an overly thick sand layer will generate a large amount of gas during the casting process, and the casting is prone to pore defects and is not easy to be uniformly thermally cured. If the thickness of the sand coating is too thin, it will be too heavy, the hardness of the casting will be high, and it will be inconvenient for fine processing.

[0035] According to the embodiment of the utility model, the casting forming mold with iron mold covered with sand is adopted, which reduces the amount of sand material used and reduces the production cost. The iron casting mold 212 can be reused, and the production efficiency is high. In addition, the obtained casting has high dimensional accuracy, small processing allowance, fine graphite, dense crystal structure, good internal quality of the casting, and high mechanical properties.

[0036] like Figure 3 As shown, according to the casting forming mold 200 of the embodiment of the utility model, the outer mold box 210 is divided into three sections, namely a bottom box 214, a middle box 211 and a top box 218. The bottom box 214 corresponds to the end flange of the main shaft, and the top box 218 corresponds to the small end flange of the main shaft.

[0037] Furthermore, if Figure 4As shown, the middle box 211 can also be divided into multiple sections, for example, the middle box is divided into three sections, namely the first middle box section 215, the second middle box section 216, and the third middle box section 217. The number of sections of the outer box 210 can be determined according to factors such as the hoisting capacity of the hoisting mechanism and the height of the sand blasting machine, and is not specifically limited here.

[0038] According to an embodiment of the utility model, the pouring system can adopt a bottom pouring type, that is, molten iron enters from the lower part of the mold cavity 300. A part of the pouring pipeline can be arranged in the bottom box 214. In order to facilitate the arrangement of the pouring system in the bottom box 214, the bottom box 214 can adopt a sand mold box. In addition, the pouring system also includes a riser and the like arranged in the top box 218. Similarly, in order to facilitate the formation of the riser and the like in the top box 218, the top box 218 can also be a sand mold box. In this case, only the middle box 211 is an iron mold covered sand mold box.

[0039] In order to obtain an iron mold-coated sand mold box, an iron mold 212 may be prepared first, and then a sand-shooting machine may be used to shoot sand on the inner surface of the iron mold to form a sand-coated layer. Figure 5 A schematic diagram showing the use of a sand blasting machine to blast sand into a segmented iron mold.

[0040] like Figure 5 As shown, the iron mold 212 is placed on the workbench 310, and the iron mold 330 is placed inside the iron mold 212, so that a sand-shooting cavity 340 is formed between the iron mold 212 and the iron mold 330. Here, the outer wheel of the iron mold 330 is consistent with the outer contour of the main shaft 100, so that the inner surface of the formed sand coating is consistent with the outer shape of the main shaft 100. In the case where the iron mold 212 is segmented, the iron mold 330 also has a corresponding number of segments and a corresponding shape, which will not be repeated here.

[0041] After the iron mold 212 is arranged, the sand-shooting coating operation is performed. Specifically, the iron mold 212 and the iron mold 330 are heated, and the sand is injected into the sand-shooting cavity 340 by using the sand-shooting machine 400, so that the sand and the iron mold 212 are fully solidified. Finally, the mold is removed to obtain the sand-coated iron mold. By performing sand-shooting coating on the iron mold segments respectively, and then stacking the multiple iron mold segments with the bottom box 214 and the top box 218, the outer mold box 210 of the molding mold according to the embodiment of the utility model can be obtained.

[0042] According to the embodiment of the utility model, the inner core 220 can be a sand core to facilitate demoulding of the casting. The inner core 220 can be directly cast on the bottom box 214. Figure 3As shown, an exhaust channel 229 may be formed in the middle of the inner core 220, and the exhaust channel extends along the height direction of the inner core 220 and is connected to the outside of the forming mold, so that the gas generated by the inner core 220 can be discharged in time during the process of molten iron casting. A plurality of risers are provided on the top cover 218 for slag discharge, exhaust, etc. The exhaust channel 229 in the inner core 220 can be connected to the exhaust riser on the top cover 218.

[0043] According to the embodiment of the utility model, when the casting mold 200 is used to manufacture the main shaft 100 of the wind turbine generator set, the outer mold box 210 and / or the inner mold core 220 can be divided into multiple sections in the axial length direction of the main shaft 100 to facilitate manufacturing. However, the casting mold 200 according to the embodiment of the utility model is not limited to being used to manufacture the main shaft of the wind turbine generator set, and can be used to manufacture other mechanical parts.

[0044] In addition, in order to reduce manufacturing costs, the embodiments of the utility model use low-cost ductile iron to manufacture large castings. As a type of ductile iron, cast ferrite ductile iron has been widely used in engineering machinery, basic parts of injection molding machines, basic parts of die-casting machines, and foundations or key parts of wind power generation. At present, the research on ductile iron for wind power generation mainly focuses on solving how to make the impact work still meet the performance requirements at low temperatures while maintaining the existing strength. However, improving the strength while ensuring the low-temperature impact work is a pair of contradictions. Improving the strength will inevitably affect the low-temperature impact work. In order to solve this problem, the utility model uses a casting molding mold with an iron mold covered with sand to form a ductile iron casting, so as to greatly improve the low-temperature impact work of the casting on the basis of ensuring the strength of the casting.

[0045] The casting forming mold with sand-coated iron mold provided by the embodiment of the utility model can further improve the structural density of ductile iron castings by utilizing the strong chilling of the metal mold, thereby improving the comprehensive mechanical properties of large castings by increasing the cooling rate of molten iron and improving the composition of molten iron. At the same time, due to the presence of the sand-coated layer 213, the graphite expansion of ductile iron can be utilized to self-compensate the castings, thereby obtaining high-quality castings. Therefore, the casting forming mold provided by the embodiment of the utility model is particularly suitable for large castings with large cross-sections.

[0046] Since the main shaft of a wind turbine generator set is usually large in size, with a wall thickness greater than or equal to 60 mm, the same ductile iron molten iron material is poured into different casting molding molds to form the main shaft of the wind turbine generator set, and the main shaft obtained by pouring with different molds is tested for performance to compare and illustrate the influence of different molds on the comprehensive performance of the main shaft. However, the ductile iron casting of the utility model is not limited to the mechanical parts of the wind turbine generator set, but can also be other large-section castings, for example, large-section castings with a wall thickness greater than or equal to 60 mm.

[0047] Next, the main shaft of a wind turbine generator set is cast by using the iron mold coated with sand mold, ordinary sand mold, and iron mold of the utility model to compare and illustrate the effect of the iron mold coated with sand mold on the improvement of casting performance.

[0048] Example 1

[0049] The molten iron is poured into the casting mold according to the embodiment of the utility model, and after cooling, the main shaft of the wind power generation group is obtained. The outer diameter of the shaft body 110 of the main shaft is 1500 mm.

[0050] The composition of molten iron is: C 3.71wt%, Si 2.48wt%, Mn 0.125wt%, P 0.025wt%, S0.02wt%, Ni 0.46wt%, Cr 0.011wt%, Mg 残 0.05wt%, the rest is iron and inevitable impurities. The molten iron pouring temperature is 1330-1360℃, and the molten iron pouring speed is 100-150kg / s.

[0051] Comparative Example 1

[0052] The molten iron of the above embodiment 1 is poured into the sand mold to obtain the main shaft of the wind turbine generator set, and the process conditions are controlled. The components and control process are the same as those in Example 1.

[0053] Comparative Example 2

[0054] The molten iron obtained in step (3) of the above embodiment 1 is poured into an iron mold to obtain the main Axis, control process conditions and control process are the same as those in Example 1.

[0055] Samples are taken from the shaft body, large end flange and small end flange of the main shaft according to the following test methods to test the tensile strength, yield strength and low temperature impact energy:

[0056] (1) Tensile strength: tested according to the method specified in GB / T 228.1;

[0057] (2) Yield strength: tested according to the method specified in GB / T 228.1;

[0058] (3) Low-temperature impact toughness at -20℃: tested according to the method specified in GB / T 229.

[0059] The specific test results of the spindles in Example 1, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below.

[0060] Table 1

[0061]

[0062] As shown in Table 1, when an iron mold-coated sand casting mold is used, while ensuring the tensile strength and yield strength, the low-temperature impact energy of the spindle can be significantly improved to meet the comprehensive performance requirements of the spindle. When the spindle is prepared by the sand casting process, the tensile strength, yield strength and low-temperature impact energy of the spindle body, large end flange and small end flange are significantly lower, and cannot meet the comprehensive performance requirements of the spindle. When the spindle is prepared by the iron mold mold, the overall comprehensive performance requirements of the spindle can be met, but the improvement effect of the low-temperature impact energy is not as good as the low-temperature impact energy effect of the spindle obtained by the iron mold-coated sand molding mold.

[0063] In addition, compared with the existing sand mold process, the iron mold sand coating process is used to manufacture ductile iron castings according to the embodiment of the utility model, which also has the following technical effects: 1) High dimensional accuracy. The dimensional accuracy of the castings obtained by the iron mold sand coating process can reach CT10, while the accuracy of the castings obtained by the sand mold process is CT12; 2) The organization is denser and the UT grade is high. The UT grade of the main shaft obtained by the iron mold sand coating process can reach UT1, while the UT grade of the main shaft obtained by the sand mold process is UT2-3; 3) The cooling time is fast, which can save 3 days of unpacking time compared with the sand mold process; 4) The utilization rate of the sand box and the site is improved, and the production capacity per unit area is increased.

[0064] The comprehensive performance of the ductile iron castings obtained by using the iron mold covered with sand molding mold according to the embodiment of the utility model is excellent, especially the low-temperature impact work of the main shaft of the wind turbine generator set can be greatly improved, reducing the risk of fracture in a low-temperature environment. Therefore, the iron mold covered with sand casting molding mold according to the utility model can be widely used in large castings in wind turbine generator sets, and can also be used in other fields for castings with high comprehensive performance requirements, especially large-section castings, and can also meet the comprehensive performance requirements.

[0065] According to another embodiment of the utility model, a casting is provided, which is made by the casting forming mold described above. As an example, the casting is a main shaft of a wind turbine generator set, and the outer diameter of the main shaft of the wind turbine generator set is greater than or equal to 1m.

[0066] According to another embodiment of the present invention, a wind turbine generator set is provided. The wind turbine generator set includes the main shaft described above.

[0067] Although exemplary embodiments of the present invention have been described in detail with reference to the accompanying drawings, those skilled in the art will appreciate that various changes in form and details may be made thereto without departing from the spirit and scope of the present invention as defined by the claims.

Claims

1. A casting forming die for forming a cast iron part, characterized in that: The casting forming mold includes an outer mold box and an inner mold core located in the outer mold box. The outer mold box includes a metal casting mold and a sand coating layer covered on the inner cavity surface of the metal casting mold. A casting cavity is formed between the outer mold box and the inner mold core. Molten iron can be poured into the casting cavity and cooled in the cavity to form a cast iron part.

2. The casting mold according to claim 1, characterized in that: The metal casting mold is an iron mold, the thickness of the iron mold is 50mm-200mm, and the thickness of the sand coating layer is 6mm-20mm.

3. The molding die according to claim 1, characterized in that: The outer mold box includes a bottom box, a top box and a middle box arranged between the bottom box and the top box, the middle box is an iron mold covered sand mold box, the top box and the bottom box are sand boxes, and the inner core is a sand core.

4. The casting mold according to claim 3, characterized in that: The middle box is divided into multiple sections.

5. The casting mold according to claim 3, characterized in that: The casting forming mold also includes a bottom pouring system, and a runner for conveying molten iron into the mold cavity is arranged in the bottom box.

6. The casting mold according to claim 3, characterized in that: A riser is arranged in the top box, and an exhaust channel is arranged in the inner core, and the exhaust channel is communicated with the riser.

7. The casting mold according to claim 3, characterized in that: In the height direction of the mold, the outer mold box and / or the inner mold core is divided into multiple sections.

8. The casting mold according to claim 3, characterized in that: The casting is the main shaft of a wind turbine generator set, and the main shaft includes a shaft body, a large end flange connected to one end of the shaft body, and a small end flange connected to the other end of the shaft body. There is also a trumpet-shaped connecting section between the large end flange and the shaft body. The bottom box corresponds to the large end flange, the middle box corresponds to the shaft body and the trumpet-shaped connecting section, and the top box corresponds to the small end flange.

9. A casting, characterized in that: The casting is made using the casting forming mold according to any one of claims 1-8.

10. The casting according to claim 9, characterized in that The casting is a main shaft of a wind turbine generator set, and the outer diameter of the main shaft is greater than or equal to 1m.

11. A wind turbine generator set, characterized in that: The wind turbine generator set comprises the casting according to any one of claims 9 or 10.

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