Filtering-free pouring system of low-slag-inclusion wind power ductile iron casting

Abstract

The utility model discloses a filtering-free pouring system of a low-slag-inclusion wind power ductile iron casting, which comprises a pouring cup, a straight pouring gate, a straight pouring gate nest, a drainage cross pouring gate, an annular cross pouring gate, a gap bridge, a tail end cross pouring gate and an inner pouring gate, and is characterized in that the pouring cup is used for blocking primary slag in molten iron to prevent the primary slag from entering the straight pouring gate; the drainage cross gate is used for reducing the flow speed of the molten iron input by the sprue and playing a role in stabilizing a flow field and scum, the annular cross gate is used for carrying out secondary scum blocking on the molten iron and uniformly draining the molten iron to the gap bridge, and the tail end cross gate is used for introducing the molten iron input by the gap bridge into the ingate. According to the structure, primary slag in molten iron is blocked through the pouring cup and the annular transverse pouring gate, the flow speed of the molten iron in the transverse pouring gate and the inner pouring gate is controlled through the reasonable section ratio of a pouring system, a large amount of secondary slag is prevented from being formed, and then a wind power ductile iron casting with the low slag inclusion amount is produced.

Description

Technical Field

[0001] The utility model relates to a non-filtering pouring system for low-slag wind power ductile iron castings, belonging to the technical field of casting systems. Background Art

[0002] The production of ductile iron castings involves a spheroidizing process in which the raw molten iron is inoculated. When the spheroidizing elements magnesium and rare earth elements are added to the molten iron, they react with the sulfur and oxygen in the molten iron to form magnesium and rare earth sulfides, oxides, magnesium silicates, or complex sulfur-oxygen compounds, resulting in a large amount of slag. Furthermore, during the subsequent transfer and pouring of the molten iron, the spheroidizing elements continuously react with sulfur and oxygen to form secondary slag. Wind power ductile iron castings operate in a complex environment and require not only sufficient strength and ductility but also low-temperature impact toughness. During the casting process, if slag from the molten iron cannot be completely removed and enters the mold, or if a large amount of secondary slag is formed due to an improperly constructed pouring system, the mechanical properties, especially the impact toughness, of the wind power ductile iron castings will be significantly reduced, thereby shortening the service life of the castings and even directly rendering them scrapped.

[0003] To reduce slag inclusions in wind turbine ductile iron castings, filters have traditionally been installed in the casting system to prevent primary slag from entering the casting cavity. This reduces the flow rate and stabilizes the flow field, thus reducing the generation of secondary slag. However, wind turbine ductile iron castings are generally large in tonnage and require long casting times, which creates the risk of filter discs becoming overloaded, softened, and broken. The use of filter discs also creates a cast iron filter chamber containing the filter discs. Directly smelting the filter discs as recycled material results in excessive slag content in the molten iron, increasing the workload of pre-furnace slag removal. Furthermore, the filter discs themselves are relatively expensive.

[0004] In view of this, it is necessary to provide a low-slag inclusion wind power ductile iron casting filterless casting system that has good slag blocking effect and can reduce the generation of secondary slag. Utility Model Content

[0005] In view of the problems existing in the above-mentioned prior art, the utility model provides a filter-free pouring system for low-slag wind power ductile iron castings, thereby solving the above-mentioned technical problems.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a filter-free pouring system for low-slag wind power ductile iron castings, the pouring system including a pouring cup, a sprue, a sprue nest, a drainage runner, a ring runner, a bridge, an end runner, and an inner runner; one side of the pouring cup is connected to the sprue; one end of the sprue is connected to the sprue nest; the side of the sprue nest is connected with multiple drainage runners; one side of the drainage runner is connected to the ring runner; the ring runner is connected with multiple bridges around; one side of the bridge is connected to the end runner; the pouring cup is used to intercept the primary slag in the molten iron to prevent it from entering the sprue, the drainage runner is used to reduce the flow rate of the molten iron input by the sprue and play a role in stabilizing the flow field and slag, the ring runner is used to perform a second slag blocking on the molten iron and drain the molten iron evenly to the bridge, and the end runner is used to introduce the molten iron input by the bridge into the inner runner.

[0007] Furthermore, the pouring cup includes a molten iron injection chamber, a molten iron outlet chamber, a gate trough, an iron plate and a drainage straight runner; a refractory gate is arranged in the gate trough to separate the molten iron injection chamber and the upper half of the molten iron outlet chamber; the iron plate is placed at the bottom of the molten iron outlet chamber and separates the molten iron outlet chamber and the drainage straight runner.

[0008] Furthermore, the height difference between the bottom surface of the molten iron outlet chamber and the bottom surface of the molten iron injection chamber is 5-6 times the diameter of the drainage sprue, and the thickness of the iron plate placed at the bottom of the molten iron outlet chamber is 5-8 mm.

[0009] Furthermore, the water inlet of the sprue is connected to the drainage sprue, the diameter of the sprue is slightly smaller than the diameter of the drainage sprue, the water outlet of the sprue is connected to the sprue nest by bottom reversal, and the diameter of the sprue nest is 2-4 times the diameter of the sprue.

[0010] Furthermore, the ratio of the cross-sectional height to the width of the drainage runner is not less than 1.5, the drainage runner is set to an arc shape with a length of not less than 200 mm, the number of the runners is 2-4, and the two ends are respectively connected to the sprue nest and the annular runner.

[0011] Furthermore, the cross section of the bridge is wide and thin and flat, with a thickness of 10-15 mm. The bridge is connected to the lower part of the annular runner and the upper part of the terminal runner, and the height ratio of the annular runner to the bridge is greater than 5.

[0012] Furthermore, the cross-sectional dimensions of the annular runner and the terminal runner are the same as those of the drainage runner, and the cross-sectional dimensions of the terminal runner and the cross-sectional dimensions of the annular runner are inverted in the up and down directions. The drainage runner and the annular runner are mainly located above the parting surface of the casting, and the terminal runner and the bridge are mainly located below the parting surface of the casting.

[0013] Furthermore, the water inlet of the ingrown channel is introduced from the bottom of the terminal runner, and the water outlet is connected to the casting cavity through the bottom reverse.

[0014] Furthermore, the sprue nest, drainage runner, annular runner, bridge, terminal runner, and ingrown runner are all located at the bottom of the casting cavity.

[0015] Furthermore, the total cross-sectional size ratio of the sprue, drainage runner, bridge and ingrown runner is 1:3-5:3-5:4-6.

[0016] The beneficial effects of the utility model are:

[0017] At the beginning of pouring, the pouring cup is filled quickly, and the slag in the molten iron in the pouring cup can float to the surface. Then the iron plate in the pouring cup melts, making the pouring cup connected to the sprue, and clean molten iron then enters the sprue. The pouring cup maintains the depth of the molten iron in the pouring cup because it is replenished with subsequent molten iron at the same time. The primary slag that is not scraped off cleanly in the molten iron always floats on the upper surface of the molten iron in the pouring cup during the pouring process.

[0018] The sprue nest, drainage runner, ring runner, bridge, end runner and ingates are all located at the bottom of the casting and can be filled quickly, thus avoiding the phenomenon of molten iron entrainment.

[0019] The cross section of the annular runner is high and narrow, and the cross section of the aisle piece is wide and thin. This structural form can retain the slag that enters the pouring system due to incomplete retention by the pouring cup in the runner, so that the molten iron can be purified twice.

[0020] The cross-sectional dimensions of the sprue, drainage runner, aisle plate and ingrate gradually increase, forming a completely open pouring system. The flow rate of molten iron in the pouring system is gradually reduced, achieving low-speed and stable filling, preventing molten iron turbulence and splashing, and reducing the formation of secondary slag.

[0021] The wind power ductile iron casting system can be used to replace the traditional casting system for placing filter plates, saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the non-filtered pouring system for low-slag wind power ductile iron castings of the utility model;

[0023] Figure 2 For the utility model Figure 1 Top view of the gating system;

[0024] Figure 3 For the utility model Figure 1 Schematic diagram of the pouring cup in the pouring system;

[0025] Figure 4For the utility model Figure 2 Middle AA section view;

[0026] Figure 5 This is a three-dimensional diagram of the casting process of a wind power ductile iron casting bearing seat according to an embodiment of the present utility model;

[0027] Figure 6 Another perspective of the casting process of the wind power ductile iron casting bearing seat in the embodiment of the present utility model;

[0028] Figure 7 This is a three-dimensional diagram of the casting process of the wind power ductile iron casting main shaft according to an embodiment of the present utility model;

[0029] Figure 8 This is another perspective of the casting process of the wind power ductile iron casting main shaft in the embodiment of the present utility model.

[0030] In the figure: 1. pouring cup; 101. molten iron injection chamber; 102. molten iron outlet chamber; 103. gate groove; 104. iron plate; 105. drainage sprue; 2. sprue; 3. sprue nest; 4. drainage runner; 5. annular runner; 6. bridge; 7. end runner; 8. inner runner; 9. wind turbine ductile iron casting bearing seat; 10. wind turbine ductile iron casting main shaft. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. The terms used herein 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. Example

[0033] refer to Figures 1 to 6 The present embodiment relates to a filter-free pouring system for a low-slag wind power ductile iron casting bearing seat, which includes: a pouring cup 1, a straight runner 2, a straight runner nest 3, a drainage runner 4, a ring runner 5, a bridge 6, an end runner 7, and an inner runner 8.

[0034] The pouring cup 1 includes a molten iron inlet chamber 101, a molten iron outlet chamber 102, a gate trough 103, an iron plate 104, and a drainage sprue 105. A refractory gate is placed in the gate trough 103 to separate the molten iron inlet chamber 101 from the upper half of the molten iron outlet chamber 102. A 6mm thick iron plate is placed at the bottom of the molten iron outlet chamber 102 to separate the molten iron outlet chamber 102 from the drainage sprue 105. The molten iron outlet chamber 102 is deeper than the molten iron inlet chamber 101, and the height difference between the bottom surface of the molten iron outlet chamber 102 and the bottom surface of the molten iron inlet chamber 101 is 5-6 times the diameter of the drainage sprue 105. When using the pouring cup to cast the ductile iron casting bearing seat, the pouring cup is first filled quickly, and the slag in the molten iron in the pouring cup can float to the surface. Then the iron plate in the pouring cup melts, so that the pouring cup is connected to the straight runner, and clean molten iron begins to enter the straight runner. Then, molten iron is continued to be poured into the molten iron injection chamber 101 of the pouring cup to maintain the depth of the molten iron in the pouring cup. The primary slag that has not been scraped off in the molten iron always floats on the upper surface of the molten iron in the pouring cup, preventing the slag from entering the straight runner.

[0035] The water inlet of sprue 2 is connected to the drainage sprue 105 and has a slightly smaller diameter than the drainage sprue 105, which helps fill the sprue and reduces air intake. The water outlet of sprue 2 is connected to the sprue nest 3 through a bottom-inverted method. The diameter of the sprue nest 3 is four times that of the sprue 2 to facilitate the deceleration of the molten iron.

[0036] The sprue nest 3 connects to three curved drainage runners 4, further reducing the flow rate of the molten iron fed by the sprue 2 while also stabilizing the flow field. The drainage runners 4 are at least 200 mm long, with a height-to-width ratio of 1.5. They are tall and narrow, and their ends are connected to the annular runner 5, facilitating the slag inclusions in the molten iron to float and accumulate on the upper surface of the annular runner 5. The cross-sectional dimensions of the annular runner 5 are identical to those of the drainage runner 4.

[0037] Six flat bridges 6 with wide and thin cross-sections are connected to the bottom of the annular runner 5, with a thickness of 12 mm. The height ratio of the annular runner 5 to the bridge 6 is greater than 5, so as to increase the height difference between the slag above the molten iron in the annular runner 5 and the bridge 6, avoid the slag adsorption area of ​​the bridge 6, and play a further slag blocking role.

[0038] The ends of bridge 6 connect to six sets of terminal runners 7. The cross-sectional dimensions of these terminal runners 7 are identical to those of the drainage runners 4 and the annular runners 5, but are oriented in the opposite direction. That is, their cross-sections are inverted in the vertical direction relative to those of the annular runners 5. These terminal runners 7 connect bridge 6 to ingrowns 8 and further reduce the molten iron flow rate and stabilize the flow field, thereby minimizing the formation of secondary slag.

[0039] Fifteen ingates 8 are introduced at the bottom of the terminal runner 7, and the ends of the ingates 8 are connected to the sand mold cavity of the casting in the form of a bottom reversal.

[0040] During pouring, the molten iron flows in the following order: pouring cup 1, sprue 2, sprue nest 3, drainage runner 4, annular runner 5, bridge 6, end runner 7, inner runner 8, and finally enters the sand mold cavity of the casting.

[0041] In this embodiment, the sprue nest 3, drainage runner 4, annular runner 5, bridge 6, terminal runner 7, and ingode 8 are preferably located at the bottom of the sand mold cavity. This allows the pouring system to be quickly filled with molten iron during mold filling, facilitating the floating of slag in the molten iron while preventing air entrainment in the pouring system. The total cross-sectional dimensions of the sprue 2, drainage runner 4, bridge 6, and ingode 8 are in a ratio of 1:4:4.5:6, creating a fully open pouring system. The velocity of the molten iron gradually slows as it flows from the sprue to the ingode, allowing sufficient time for slag to float within the pouring system. This prevents splashing and air entrainment during mold filling, reduces oxidation of the molten iron during filling, and reduces the generation of secondary slag.

[0042] When using the pouring system provided in Example 1 to pour a wind power ductile iron casting bearing seat, the specific pouring method and steps are as follows:

[0043] Step 1: Use the pouring system in this embodiment to prepare a casting sand mold. After the casting sand mold is assembled, use a casting adhesive to stick the sand box corresponding to the pouring cup 1 and the casting sand mold together, so that the drainage straight runner 105 of the pouring cup 1 is connected to the straight runner 2, and place an iron plate 104 at the bottom of the molten iron outlet chamber 102 of the pouring cup 1.

[0044] Step 2: Use an electric furnace to melt ductile iron molten iron according to the composition requirements. After the composition is qualified, quickly heat the molten iron to 1520~1540℃, then turn off the power and let the molten iron stand for 5~8 minutes. During the standing period, sprinkle the slag remover into the molten iron repeatedly and remove the slag.

[0045] Step 3: After the standing period, pour the molten iron into the ladle according to the pouring weight requirements, use the wire feeding method to spheroidize the molten iron, and then sprinkle the slag remover again and beat the slag.

[0046] Step 4: Transfer the molten iron ladle after the spheroidizing inoculation treatment to the casting sand mold, measure the temperature of the molten iron, place slag-blocking cotton at the ladle mouth, and pour at a temperature of 1350-1380°C. First, quickly pour the molten iron into the molten iron injection chamber 101 within a time range of 15-20 seconds until the molten iron in the pouring cup 1 is almost full. When the molten iron level in the pouring cup 1 begins to drop, continue pouring molten iron into the molten iron injection chamber 101 and keep the liquid level of the molten iron in the pouring cup 1 always in a state of being nearly full. Stop pouring when the weight of the poured molten iron reaches the expected weight. During the pouring process, the molten iron is subjected to inoculation treatment to improve the inoculation effect and prevent inoculation decline. Example

[0047] refer to Figure 1-5 and Figure 7-8 This embodiment relates to a filter-free pouring system for a low-slag wind power ductile iron casting main shaft, which includes: a pouring cup 1, a straight runner 2, a straight runner nest 3, a drainage runner 4, a ring runner 5, a bridge 6, an end runner 7, and an inner runner 8.

[0048] The pouring cup 1 includes a molten iron inlet chamber 101, a molten iron outlet chamber 102, a gate trough 103, an iron plate 104, and a drainage sprue 105. A refractory gate is placed in the gate trough 103 to separate the molten iron inlet chamber 101 from the upper half of the molten iron outlet chamber 102. A 6mm thick iron plate is placed at the bottom of the molten iron outlet chamber 102 to separate the molten iron outlet chamber 102 from the drainage sprue 105. The molten iron outlet chamber 102 is deeper than the molten iron inlet chamber 101, and the height difference between the bottom surface of the molten iron outlet chamber 102 and the bottom surface of the molten iron inlet chamber 101 is 5 to 6 times the diameter of the drainage sprue 105. When using the pouring cup to cast the ductile iron casting bearing seat, the pouring cup is first filled quickly, and the slag in the molten iron in the pouring cup can float to the surface. Then the iron plate in the pouring cup melts, so that the pouring cup is connected to the straight runner, and clean molten iron begins to enter the straight runner. Then, molten iron is continued to be poured into the molten iron injection chamber 101 of the pouring cup to maintain the depth of the molten iron in the pouring cup. The primary slag that has not been scraped off in the molten iron always floats on the upper surface of the molten iron in the pouring cup, preventing the slag from entering the straight runner.

[0049] The water inlet of sprue 2 is connected to the drainage sprue 105 and has a slightly smaller diameter than the drainage sprue 105, which helps fill the sprue and reduces air intake. The water outlet of sprue 2 is connected to the sprue nest 3 through a bottom-inverted method. The diameter of the sprue nest 3 is three times the diameter of the sprue 2 to facilitate the deceleration of the molten iron.

[0050] The sprue nest 3 connects to three curved drainage runners 4, further reducing the flow rate of the molten iron fed by the sprue 2 while also stabilizing the flow field. The drainage runners 4 are at least 200 mm long, with a height-to-width ratio of 1.5. They are tall and narrow, and their ends are connected to the annular runner 5, facilitating the slag inclusions in the molten iron to float and accumulate on the upper surface of the annular runner 5. The cross-sectional dimensions of the annular runner 5 are identical to those of the drainage runner 4.

[0051] Six flat bridges 6 with wide and thin cross-sections are connected to the bottom of the annular runner 5, with a thickness of 15 mm. The height ratio of the annular runner 5 to the bridge 6 is greater than 5, so as to increase the height difference between the slag above the molten iron in the annular runner 5 and the bridge 6, avoid the slag adsorption area of ​​the bridge 6, and play a further slag blocking role.

[0052] The ends of bridge 6 connect to six sets of terminal runners 7. The cross-sectional dimensions of these terminal runners 7 are identical to those of the drainage runners 4 and the annular runners 5, but are oriented in the opposite direction. That is, their cross-sections are inverted in the vertical direction relative to those of the annular runners 5. These terminal runners 7 connect bridge 6 to ingrowns 8 and further reduce the molten iron flow rate and stabilize the flow field, thereby minimizing the formation of secondary slag.

[0053] Twelve ingates 8 are introduced at the bottom of the terminal runner 7, and the ends of the ingates 8 are connected to the sand mold cavity of the casting in the form of a bottom reversal.

[0054] During pouring, the molten iron flows in the following order: pouring cup 1, sprue 2, sprue nest 3, drainage runner 4, annular runner 5, bridge 6, end runner 7, inner runner 8, and finally enters the sand mold cavity of the casting.

[0055] Furthermore, the sprue nest 3, drainage runner 4, annular runner 5, bridge 6, terminal runner 7, and ingrate 8 are all located at the bottom of the sand casting cavity. During mold filling, the gating system is quickly filled with molten iron, which facilitates the floating of dross in the molten iron and prevents air entrainment in the gating system. The total cross-sectional dimensions of the sprue 2, drainage runner 4, bridge 6, and ingrate 8 are in a ratio of 1:3.5:4.5:5.5, creating a fully open gating system. The molten iron gradually slows as it flows from the sprue to the ingrate, allowing dross ample time to float within the gating system. This prevents splashing and air entrainment during mold filling, reduces oxidation, and minimizes the generation of secondary slag.

[0056] When using the pouring system provided in this embodiment to pour the main shaft of a wind power ductile iron casting, the specific pouring method and steps are as follows:

[0057] Step 1: Use the pouring system in this embodiment to prepare a casting sand mold. After the casting sand mold is assembled, use a casting adhesive to stick the sand box corresponding to the pouring cup 1 and the casting sand mold together, so that the drainage straight runner 105 of the pouring cup 1 is connected to the straight runner 2, and place an iron plate 104 at the bottom of the molten iron outlet chamber 102 of the pouring cup 1.

[0058] Step 2: Use an electric furnace to melt ductile iron molten iron according to the composition requirements. After the composition is qualified, quickly heat the molten iron to 1520-1540℃, then turn off the power and let the molten iron stand for 5-8 minutes. During the standing period, sprinkle the slag remover into the molten iron repeatedly and remove the slag.

[0059] Step 3: After the standing period, pour the molten iron into the ladle according to the pouring weight requirements, use the wire feeding method to spheroidize the molten iron, and then sprinkle the slag remover again and beat the slag.

[0060] Step 4: Transfer the molten iron ladle after the spheroidizing inoculation treatment to the casting sand mold, measure the temperature of the molten iron and place slag-blocking cotton at the ladle mouth of the molten iron ladle, and pour at a temperature of 1350-1380°C. First, quickly pour the molten iron into the molten iron injection chamber 101 within a time range of 15-20s until the molten iron in the pouring cup 1 is almost full. When it is observed that the molten iron liquid level in the pouring cup 1 begins to drop, continue to pour molten iron into the molten iron injection chamber 101 and keep the liquid level of the molten iron in the pouring cup 1 always in a state of being close to full. Stop pouring when the weight of the poured molten iron reaches the expected weight. During the pouring process, the molten iron is subjected to inoculation treatment to improve the inoculation effect and prevent inoculation decline.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A filter-free pouring system for low-slag wind power ductile iron castings, characterized in that: The pouring system comprises a pouring cup (1), a sprue (2), a sprue nest (3), a drainage runner (4), an annular runner (5), a bridge (6), an end runner (7), and an inner runner (8); one side of the pouring cup (1) is connected to the sprue (2); one end of the sprue (2) is connected to the sprue nest (3); a side of the sprue nest (3) is connected to a plurality of drainage runners (4); one side of the drainage runner (4) is connected to the annular runner (5); the annular runner (5) is connected to the inner runner (8) on all sides. There are a plurality of bridges (6); one side of the bridge (6) is connected to a terminal runner (7); the pouring cup (1) is used to intercept the primary slag in the molten iron to prevent it from entering the straight runner (2); the drainage runner (4) is used to reduce the flow rate of the molten iron input from the straight runner (2) and play a role in stabilizing the flow field and slag; the annular runner (5) is used to perform a second slag blocking on the molten iron and drain the molten iron evenly to the bridge (6); the terminal runner (7) is used to guide the molten iron input from the bridge (6) into the inner runner (8).

2. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The pouring cup (1) comprises a molten iron injection chamber (101), a molten iron outlet chamber (102), a gate trough (103), an iron plate (104) and a drainage sprue (105); a refractory gate is arranged in the gate trough (103) to separate the molten iron injection chamber (101) and the upper half of the molten iron outlet chamber (102); the iron plate (104) is placed at the bottom of the molten iron outlet chamber (102) and separates the molten iron outlet chamber (102) from the drainage sprue (105).

3. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 2, characterized in that: The height difference between the bottom surface of the molten iron outlet chamber (102) and the bottom surface of the molten iron injection chamber (101) is 5-6 times the diameter of the drainage sprue (105), and the thickness of the iron plate (104) placed at the bottom of the molten iron outlet chamber (102) is 5-8 mm.

4. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The water inlet of the sprue (2) is connected to the drainage sprue (105), the diameter of the sprue (2) is slightly smaller than the diameter of the drainage sprue (105), the water outlet of the sprue (2) is connected to the sprue nest (3) by bottom reversal, and the diameter of the sprue nest (3) is 2-4 times the diameter of the sprue (2).

5. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The ratio of the cross-section height to the width of the drainage runner (4) is not less than 1.

5. The drainage runner (4) is configured as an arc with a length of not less than 200 mm, with 2 to 4 runners in number, and the two ends are respectively connected to the sprue nest (3) and the annular runner (5).

6. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The cross section of the bridge (6) is wide and thin and flat, with a thickness of 10-15 mm. The bridge is connected to the lower part of the annular runner (5) and the upper part of the terminal runner (7). The height ratio of the annular runner (5) to the bridge (6) is greater than 5.

7. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The cross-sectional dimensions of the annular runner (5) and the terminal runner (7) are the same as the cross-sectional dimensions of the drainage runner (4); the cross-sectional dimensions of the terminal runner (7) and the cross-sectional dimensions of the annular runner (5) are inverted in the vertical direction; the drainage runner (4) and the annular runner (5) are mainly located above the mold parting surface, and the terminal runner (7) and the bridge are mainly located below the mold parting surface.

8. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The water inlet of the ingrown channel (8) is introduced from the bottom of the terminal runner (7), and the water outlet is connected to the casting cavity through the bottom reverse.

9. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The sprue nest (3), the drainage runner (4), the annular runner (5), the bridge (6), the terminal runner (7), and the inner runner (8) are all located at the bottom of the casting cavity.

10. The filter-free pouring system for low-slag wind power ductile iron castings according to claim 1, characterized in that: The total cross-sectional dimensions of the sprue (2), the drainage runner (4), the bridge (6) and the ingrown runner (8) are in a ratio of 1:3-5:3-5:4-6.

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