Casting process model and green sand casting process of thick and large ductile iron casting

Abstract

The invention relates to the field of sand casting, aims to solve the problems of internal shrinkage porosity and appearance slag inclusion of a thick and large ductile iron casting cast by green sand, and provides a casting process model which comprises a pouring system part and a riser part, the pouring system part comprises a pouring gate model, a straight pouring gate model, a filter screen model, a transverse pouring gate model and an inner pouring gate model; the riser part comprises a riser neck model, a riser body model and a V-shaped groove model. The bottom end of the sprue model is connected with the sprue model, the filter screen model is arranged at the bottom of the sprue model, the cross gate model is provided with a plurality of bent parts, the front end is connected with the filter screen model, and the rear end is connected with the ingate model; one end of the ingate model is connected with the cross gate model, and the other end is connected with the casting model; a riser neck model is arranged on the top of the casting model, a riser body model is arranged on the riser neck model, and a V-shaped groove model is arranged on the top of the riser body model. The casting process model provided by the invention can effectively play a feeding role, and slag inclusion of a casting is reduced.

Description

Technical Field

[0001] The invention relates to the field of sand casting, in particular to a casting process model and a green sand casting process for thick ductile iron castings. Background Art

[0002] Green sand casting of thick ductile iron parts is prone to shrinkage problems. Common process solutions are: increasing the chill, adding multiple chills, increasing the size of the riser, adding multiple risers, using heating risers, adjusting the pouring temperature, etc. Such process solutions are not only complex in process and cumbersome in production operation, but also very costly in production. Because of the cumbersome operation, the operation process is often unstable, resulting in unstable quality. At present, the solution to shrinkage basically does not use the pouring system.

[0003] To solve the appearance defects of castings, such as slag inclusion, the common process solution is to make the ingates thinner, such as setting the thickness of the ingates to 2-3mm, adding filters, etc. However, an overly thin ingates will result in a very short solidification time of the ingates, and the high-temperature molten iron in the pouring system cannot feed the casting through the ingates, and the shrinkage-feeding effect of the entire pouring system on the casting is reduced.

[0004] At present, a new process scheme is urgently needed to make full use of the pouring system to compensate for the shrinkage of castings, so as to reduce the number of risers, reduce the volume of risers, improve the yield rate, reduce production costs, simplify production operations, and reduce labor intensity; by optimizing the structure of the pouring system, the pouring system can play its slag blocking function while playing the role of shrinkage compensation, avoiding the problem of slag inclusion in the appearance of castings. Summary of the invention

[0005] The purpose of the present invention is to provide a casting process model to solve the problem that when the existing model forms a sand mold cavity, the runner in the cavity is difficult to solve the shrinkage of the casting, resulting in cumbersome production operations, high production costs and unstable casting quality.

[0006] The present invention also aims to provide a green sand casting process for thick ductile iron castings, which can better solve the problem of slag inclusion in castings.

[0007] Another object of the present invention is to provide an activated carbon underwear and a sewing process thereof, so as to solve the problem that the crotch part of the activated carbon underwear has a multi-layer structure and the wearing comfort is poor.

[0008] The embodiments of the present invention are implemented by the following technical solutions:

[0009] A casting process model comprises: a pouring system part and a riser part; wherein the pouring system part comprises: a gate model, a sprue model, a filter mesh model, a runner model, and an ingate model; and the riser part comprises: a riser neck model, a riser body model, and a V-groove model.

[0010] The gate model is at the highest position of the entire casting process model, and the gate model is a cone with a large top and a small bottom; the bottom of the gate model is connected to the sprue model, the upper part of the sprue model is a cylinder with a small top and a large bottom, and the lower part of the sprue model is a cube; the bottom of the sprue model is a filter mesh model, 1 / 4 of the filter mesh model in the height direction is on the upper part of the mold, and 3 / 4 of the filter mesh model in the height direction is on the lower mold of the mold; the runner model is divided into multiple bending parts with different lengths and different extension directions, the front end is connected to the filter mesh model, the rear end is connected to the ingode model, and the cross section of the runner model is a high trapezoid with a narrow top and a wide bottom; the ingode model is arranged on the side and bottom of the ingode model, the cross section of the ingode model is a rectangle, the width dimension is greater than the thickness dimension, one end of the ingode model is connected to the runner model, and the other end is connected to the casting model; a riser neck model is arranged on the top of the casting model, a riser body model is arranged on the riser neck model, and a V-shaped groove model is arranged on the top of the riser body model.

[0011] Preferably, the gate model is a cone with a larger upper part and a smaller lower part, the minimum diameter of the lower part of the gate is greater than or equal to the minimum diameter of the sprue, and the top surface of the gate model is at least 50 mm higher than the top surface of the riser body model.

[0012] Preferably, the upper part of the sprue model is a cylinder with a small top and a large bottom, and the lower part of the sprue model is a cube; the minimum diameter of the sprue model is at least 4 times the thickness of the ingrown model; the side length of the lower cube of the sprue model is 10 mm smaller than the side length of the filter mesh model, that is, 5 mm smaller on one side.

[0013] Preferably, in the height direction, 3 / 4 of the height of the filter mesh model is arranged on the lower mold, and 1 / 4 of the height is arranged on the upper mold.

[0014] Preferably, the runner model includes a plurality of bent parts, each part has different lengths, extends in different directions, and has a high trapezoidal cross section.

[0015] Preferably, the multiple bent parts of the runner model are connected end to end, and the angle between the side walls corresponding to adjacent bent parts is 90°-150°.

[0016] Preferably, the runner model includes: a first bending portion, which is arranged in the lower mold and connected to the filter mesh model of the lower mold; a second bending portion, which is arranged in the upper mold and connected to the first bending portion, and is between the first and second bending portions and is 90°; a third bending portion, which is arranged in the upper mold and connected to the second bending portion, and is 100°-150° between the second and third bending portions; a fourth bending portion, which is arranged in the upper mold and connected to the third bending portion, and is 90° between the fourth bending portion and the second bending portion; a fifth bending portion, which is arranged in the upper mold and connected to the fourth bending portion, and is 90° between the fourth bending portion and the fifth bending portion.

[0017] Preferably, the cross section of the runner model is a high trapezoid, the upper width of the high trapezoid is 1 / 2 of the lower width, and the height of the high trapezoid is 4 times the upper width. The average width of the cross section of the runner model is 1.5-2 times the thickness of the ingrow model.

[0018] Preferably, the ingate model is rectangular, the width of the cross section of the ingate model is at least 2-5 times the thickness of the ingate model, and the thickness of the ingate model is 0.4-0.6 times the thickness of the casting part connected to the ingate model.

[0019] Preferably, the gate model is connected to the lower side of the runner model.

[0020] Preferably, the riser neck pattern is located on the top surface of the casting and away from the sprue pattern.

[0021] Preferably, the riser body model is above the riser neck model, the minimum diameter of the riser body model is at least twice the maximum thickness of the casting model, and the height of the riser body model is 1.2-2 times the minimum diameter of the riser body model.

[0022] Preferably, the V-groove model is located at the top of the riser body, the length direction of the V-groove runs through the diameter direction of the riser body model, the cross-sectional width of the V-groove model is 1 / 3-1 / 5 of the minimum diameter of the riser body model, the cross-sectional height of the V-groove model is 1-1.5 times the maximum cross-sectional width of the V-groove model, and the slope of the inclined surface of the V-groove is 20-45 degrees.

[0023] A green sand casting process for thick ductile iron castings includes:

[0024] S100, placing the casting process model according to any one of claims 1 to 7 in a sand box, and then filling the sand box with sand and compacting the sand;

[0025] S200, after taking the casting process model, a sand mold with a mold cavity in the shape of the model is obtained, molten iron is poured from the pouring cup of the sand mold until the molten iron fills the riser body, and then cooled to obtain a cooling piece, and the riser part and the runner part on the cooling piece are cut off to obtain a casting;

[0026] In the above S200, when the injection of molten iron into the sand mold is stopped, the pouring cup is kept full.

[0027] Preferably, the compaction pressure in S100 is 100-120 N / cm 2 The pouring temperature of the molten iron in S200 is 1310-1360° C. The components of the molten iron include 3.5-3.6wt% C and 2.3-2.5wt% Si. After the pouring is completed, the pouring cup remains full.

[0028] The present invention has at least the following beneficial effects:

[0029] In the casting process model provided by the present invention, a filter mesh model is arranged in the pouring system part, and multiple bending parts of the cross runner model are designed, as well as a larger height ratio, i.e., the cross runner model height / inner runner model thickness, and the inner runner model is arranged on the side and near the bottom of the cross runner model; all of the above are for improving the slag blocking function of the pouring system, so that impurities in the molten iron can stay in the straight runner and the cross runner, and will not flow into the casting, thereby avoiding slag inclusion defects in the casting.

[0030] In the casting process model provided by the present invention, in the pouring system part, the thickness of the ingrowth model is 0.4-0.6 times the thickness of the shrinkage compensation part of the casting, the average cross-sectional width of the runner model is at least 1.5 times the thickness of the ingrowth model, and the minimum diameter of the straight runner model is at least 4 times the thickness of the ingrowth model; all of the above make the solidification time of the ingrowth, the runner and the straight runner long enough, so that the pouring system can effectively compensate for the shrinkage of the casting.

[0031] In the casting process model provided by the present invention, the riser part is arranged on the top surface of the casting model, the minimum diameter dimension of the riser body model is at least twice the maximum thickness dimension of the casting model, and the height dimension of the riser body model is 1.2-2 times the minimum diameter dimension of the riser model; a V-shaped groove is arranged on the top of the riser body model; thereby, the riser part can fully compensate for the shrinkage of the casting.

[0032] In summary, the casting process model provided by the present invention can effectively solve the internal shrinkage and appearance slag inclusion problems of thick ductile iron castings cast by green sand casting, and has a high yield rate, simple operation process, high production efficiency and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 It is a structural schematic diagram of the casting process model;

[0035] Figure 2 It is a top view of the casting process model;

[0036] Figure 3 , Figure 4 It is a cross-sectional view of the casting process model;

[0037] Figure 5 It is a side view of the gating system part;

[0038] Icons: 1-gate model, 2-sprue model, 21-upper part of sprue model, 22-lower part of sprue model, 3-filter model, 31-upper part of filter model, 32-lower part of filter model, 4-runner model, 41-first bending part, 42-second bending part, 43-third bending part, 44-fourth bending part, 45-fifth bending part, 5-ingentate model, 6-casting model, 7-riser model, 71-riser neck model, 72-riser body model, 73-V-groove model. DETAILED DESCRIPTION

[0039] In order to make the purpose, method scheme and advantages of the embodiments of the present invention clearer, the method scheme in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0040] Example 1: Figure 1 As shown, a casting process model includes: a pouring system part and a riser part; wherein the pouring system part includes: a gate model 1, a straight runner model 2, a filter mesh model 3, a cross runner model 4, and an inner runner model 5; the riser part includes: a riser neck model 71, a riser body model 72, and a V-groove model 73.

[0041] The gate model 1 is at the highest position of the entire casting process model, and the gate model 1 is a cone with a large top and a small bottom; the bottom of the gate model 1 is connected to the sprue model 2, the upper part of the sprue model 2 is a cylinder with a small top and a large bottom, and the lower part of the sprue model 2 is a cube; the bottom of the sprue model 2 is the filter mesh model 3, 1 / 4 of the height direction of the filter mesh model 3 is in the upper mold of the mold, and 3 / 4 of the height direction of the filter mesh model 3 is in the lower mold of the mold; the runner model 4 is divided into different lengths, different extension directions, and multiple bending parts, and the front end It is connected to the filter screen model 3, and the rear end is connected to the ingrate model 5, and the cross section of the runner model 4 is a high trapezoid that is narrow at the top and wide at the bottom; the ingrate model 5 is arranged on the side and near the bottom of the runner model 4, the cross section of the ingrate model 5 is rectangular, the width dimension is greater than the thickness dimension, one end of the ingrate model 5 is connected to the runner model 4, and the other end is connected to the casting model 6; a riser neck model 71 is arranged on the top of the casting model 6, a riser body model 72 is arranged on the riser neck model 71, and a V-groove model 73 is arranged on the top of the riser body model 72.

[0042] In the specific implementation process, the casting model 6 is used to form the mold cavity of the required casting on the sand mold, and after the molten iron is injected into the mold cavity and cooled, a casting with the same structure as the mold cavity can be formed. Therefore, the shape of the casting model 6 is mainly determined by the required product structure, and this embodiment does not make specific restrictions. The model in this embodiment is used to form a runner for the flow of molten iron, a mold cavity adapted to the required casting structure, and a riser for storing molten iron on the molding sand. The three are interconnected, so the design of each model structure in this embodiment corresponds to the structural design of the runner, the mold cavity, and the riser. The molten iron enters from the pouring cup and flows from the straight runner into the runner. Since the runner is a narrow and high type with a height greater than the width and has a bending portion, impurities in the molten iron are more likely to float and be blocked in the upper half of the runner. The clean molten iron removed from the impurities flows from the runner through the inner runner and enters the casting. The cross section of the runner model 4 can be a trapezoidal shape with a small top and a large bottom, which further improves the slag blocking effect of the runner.

[0043] The mold as a whole can be Figure 3 The above figure is obtained by connecting the upper die and the lower die.

[0044] Embodiment 2: In order to further improve the slag blocking effect of the pouring system, improvements are made on the basis of Embodiment 1, such as Figure 2 , Figure 3 As shown, in this embodiment, a filter mesh model 3 is added at the bottom of the sprue.

[0045] During the specific implementation process, the height direction of the filter mesh model 3 is obtained through production practice, and its 3 / 4 height part is set in the lower mold, and the 1 / 4 height part is set in the upper mold, which can better meet the slag blocking effect of the casting system.

[0046] Embodiment 3: In order to further improve the slag blocking effect of the pouring system, improvements are made on the basis of Embodiment 1, such as Figure 2 , Figure 3 As shown, in this embodiment, the runner model 4 includes a plurality of bending parts, each part has different lengths and extends in different directions. The plurality of bending parts of the runner model 4 are connected end to end, and the angle between the side walls corresponding to the adjacent bending parts is 90°-150°.

[0047] In the specific implementation process, the angle between the corresponding side walls refers to the angle between the outer wall and the outer wall of the strip model, and the angle between the inner wall and the inner wall. The angle between the strip models can adjust the slag blocking effect of the runner, but if the slag blocking effect is pursued blindly, the molten iron will make a sharp turn during the flow of the runner, aggravating energy consumption, and then it is necessary to increase the filling pressure of the straight runner to better control the filling capacity and the flow rate of the molten iron. Therefore, this embodiment limits the angle between adjacent strip models while considering the straight runner. The first bending portion is arranged on the lower mold and connected to the filter mesh model 3 of the lower mold; the second bending portion is arranged on the upper mold and connected to the first bending portion, and is 90° between the first and second bending portions; the third bending portion is arranged on the upper mold and connected to the second bending portion, and is 100°-150° between the second and third bending portions; the fourth bending portion is arranged on the upper mold and connected to the third bending portion, and is 90° between the fourth bending portion and the second bending portion; the fifth bending portion is arranged on the upper mold and connected to the fourth bending portion, and is 90° between the fourth bending portion and the fifth bending portion.

[0048] Embodiment 4: In order to further improve the slag blocking effect of the pouring system, improvements are made on the basis of Embodiment 1, such as Figure 3 , Figure 4 As shown, in this embodiment, the cross section of the runner model 4 is in the shape of a high trapezoid.

[0049] In the specific implementation process, the cross section of the runner model 4 is a high trapezoid, which means that the height of the trapezoid is greater than the width. The upper width of the high trapezoid can be 1 / 2 of the lower width, and the height of the high trapezoid can be 4 times the upper width. The average width of the cross section of the runner model 4 is 1.5-2 times the thickness of the ingrow model 5, so as to obtain a larger height ratio, that is, the height of the runner model 4 / the thickness of the ingrow model 5, so as to better meet the slag blocking effect of the runner.

[0050] Embodiment 5: In order to further improve the slag blocking effect of the pouring system, improvements are made on the basis of Embodiment 1, such as Figure 4 , Figure 5 As shown, in this embodiment, the gate model 5 is arranged on the side of the runner model 4, close to the bottom.

[0051] During the specific implementation process, the density of the slag in the molten iron is lower than the density of the molten iron, and the slag will float upward during the flow in the runner. The ingrowth model 5 is set on the side and close to the bottom of the runner model 4. When the floating height of the slag in the molten iron exceeds the thickness of the ingrowth model 5, the slag in the molten iron is prevented from flowing into the ingrowth, thereby obtaining a casting with a clean appearance.

[0052] Example 6: In order to ensure that the pouring system can effectively compensate for the shrinkage of the casting, improvements are made based on Example 1. In this example, the cross-section of the ingrow model 5 is rectangular, and the width of the cross-section is at least 2-5 times the thickness of the ingrow model 5. The thickness of the ingrow model 5 is 0.4-0.6 times the thickness of the connected part of the casting.

[0053] During the specific implementation process, in order to better achieve slag blocking, the thickness of the ingrowth is usually designed to be relatively thin, generally 2-3mm, but in this embodiment, the ingrowth takes more consideration of its shrinkage compensation effect, so the thickness of the ingrowth in this embodiment is thicker than the conventional design, and the thickness of the ingrowth model 5 is 0.4-0.6 times the thickness of the connected part of the casting. In this embodiment, the thickness of the casting connected to the ingrowth is 25mm, so the thickness of the ingrowth is 12mm.

[0054] In order to allow the entire pouring system to play an effective shrinkage compensation role, the thickness of the ingrow model 5 has been made as thick as 12mm in this embodiment, and the solidification time of each part of the cross runner model 4, the straight runner model 2, the filter mesh model 3, and the gate model 1 must be greater than the solidification time of the ingrow model 5, so that the high-temperature molten iron in the gate model 1 can flow through the straight runner model 2, the filter mesh model 3, the cross runner model 4, and the ingrow model 5 to form a cavity and compensate for the shrinkage of the casting. Therefore, in this embodiment, it is particularly required that the average width of the cross runner cross section is at least 1.5 times the height of the ingrow. The minimum diameter of the straight runner model 2 is 4 times the thickness of the ingrow model 5, the cross-sectional size of the filter mesh model 3 is larger than the cross-sectional size of the cross runner model 4, and the minimum diameter of the gate model 1 is greater than or equal to the minimum diameter of the straight runner model 2.

[0055] Embodiment 7: In order to ensure the shrinkage compensation capability of the riser, improvements are made on the basis of Embodiment 1, such as Figure 4 As shown, in this embodiment, the riser part is arranged on the top surface of the casting model 6, the minimum diameter dimension of the riser body model 72 is at least twice the maximum thickness dimension of the casting model 6, and the height dimension of the riser body model 72 is 1.2-2 times the minimum diameter dimension of the riser model 7; a V-shaped groove is arranged on the top of the riser body model 72.

[0056] For example, when the casting is a steering seat, it is a thick ductile iron casting, and the solidification time of the casting is relatively long. In order to use only one riser in this embodiment, the structure of the riser is improved. The riser is shown in 4. The end of the riser away from the ingrowth is connected to the top surface of the casting, and a V-shaped groove structure is provided on the top to improve its shrinkage compensation efficiency. At the same time, the diameter and height dimensions of the riser body are also limited, so that the volume of the riser is large enough, and when it is used for shrinkage compensation of thick castings, its shrinkage compensation efficiency can be ensured.

[0057] Embodiment 8: A green sand casting process for thick ductile iron castings comprises:

[0058] S100, placing the casting process model in a sand box, and then filling the sand box with sand and compacting the sand;

[0059] S200, after removing the casting process model, a sand mold with a mold cavity in the shape of the model is obtained, molten iron is poured from the pouring cup of the sand mold until the molten iron fills the riser, and then cooled to obtain a cooling piece, and the corresponding parts of the riser and runner on the cooling piece are cut off to obtain a casting;

[0060] In S200, when the injection of molten iron into the sand mold is stopped, the pouring cup remains full.

[0061] During the specific implementation process, the inner cavity of the casting refers to the cavity formed by the casting model 6 on the sand mold. After the pouring is completed, the liquid level of the pouring cup needs to be kept in a full cup state, that is, the entire pouring cup is filled with high-temperature molten iron. In the full cup state, the pouring cup liquid surface maintains a certain pressure on the riser. When the high-temperature molten iron of the casting solidifies and cools, the liquid level of the pouring cup will drop, and the casting will be compensated for shrinkage through the straight runner, cross runner, inner runner and riser, thereby avoiding shrinkage defects inside the casting.

[0062] Example 9: In order to make full use of graphitization expansion, improvements were made on the basis of Example 8. In this example, the compaction pressure in S100 is 100-120N / cm2, the pouring temperature of the molten iron in S200 is 1310-1360°C, and the components of the molten iron include 3.5-3.6wt% C and 2.3-2.5wt% Si.

[0063] During the specific implementation process, the key components C and Si in the molten iron that affect the shrinkage of the casting are constrained. In this embodiment, 3.5-3.6wt% C and 2.3-2.5wt% Si are used to reduce the shrinkage of the molten iron, and graphitization expansion is used to prevent shrinkage defects in the casting. In order to further reduce the shrinkage of the molten iron, this embodiment also adopts a lower pouring temperature. In terms of molding compaction pressure, a sufficiently high molding compaction pressure is required to obtain a sand mold with sufficient hardness and strength. Only a sand mold with sufficient hardness and strength can withstand the pressure of graphitization expansion in the molten iron and better solve the shrinkage problem inside the casting. Therefore, this embodiment limits the molding compaction pressure to 100-120N / cm 2 .

[0064] In summary, in order to solve the internal shrinkage and appearance slag inclusion problems of thick ductile iron castings cast by green sand casting, the present invention has made improvements in multiple aspects, namely: the pouring system, the riser, the chemical composition, the pouring temperature, the molding compaction pressure, and the pouring cup liquid level requirements. With the joint action of various aspects, the internal shrinkage and appearance slag inclusion problems of thick ductile iron castings cast by green sand casting are solved.

[0065] The pouring system includes the gate, sprue, filter, runner and ingates. The high-temperature molten iron flows through various parts of the pouring system and enters the mold cavity, so that the casting obtains a complete shape. The slag blocking function of the pouring system solves the slag inclusion problem on the casting surface, so that the casting obtains a clean surface. The shrinkage compensation function of the pouring system provides the casting with an appropriate amount of shrinkage compensation, so that the casting obtains a dense internal structure.

[0066] In terms of risers, sufficient liquid iron is provided to compensate for the shrinkage of the casting, avoid shrinkage inside the casting, and give the casting a dense internal structure.

[0067] In terms of chemical composition, the appropriate C content and Si content can fully exert the graphitization expansion capacity of the high-temperature molten iron, thereby offsetting the shrinkage inside the casting and giving the casting a dense internal structure.

[0068] In terms of pouring temperature, a lower pouring temperature can reduce the shrinkage of molten iron, avoid shrinkage inside the casting, and make the casting obtain a dense internal structure.

[0069] In terms of molding compaction pressure, a sufficiently high molding compaction pressure can obtain a sand mold with higher hardness and higher strength, thereby resisting the extrusion of the sand mold by the graphite expansion in the molten iron, so that the casting has a dense internal structure.

[0070] Regarding the requirements for the liquid level of the pouring cup, the present invention requires the pouring system to provide an appropriate amount of shrinkage compensation, so there are special requirements for the liquid level of the pouring cup after pouring. The liquid level of the pouring cup after pouring needs to be as full as possible.

[0071] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A casting process model, characterized in that: include: A gate model, wherein the gate model is used to form a gate cup on the sand mold; A sprue model, the bottom end of the gate model is connected to the top end of the sprue model, and the sprue model is used to form a sprue on the sand mold; A filter mesh model, one end of which is connected to the sprue model; A horizontal casting model, one end of which is connected to the other end of the filter mesh model, the height of the horizontal casting model is greater than the width, the horizontal casting model has at least one bending portion, and the horizontal casting model is used to form a horizontal runner on the sand mold; An in-casting model, the other end of the horizontal casting model is connected to one end of the in-casting model, and the in-casting model is used to form an ingate on the sand mold; A casting model, the other end of the cast-in model is connected to the casting model, and the casting model is used to form a cavity on the sand mold; A riser neck model, wherein the top end of the casting model is connected to the bottom end of the riser neck model; A riser body model, wherein the bottom end of the riser body model is connected to the top end of the riser neck model; A V-shaped groove model, the bottom end of which is connected to the top end of the riser body model.

2. The casting process model according to claim 1, characterized in that: The gate model has a structure that is larger at the top and smaller at the bottom, and the minimum cross-sectional dimension of the gate model is greater than or equal to the minimum cross-sectional dimension of the sprue.

3. The casting process model according to claim 1, characterized in that: The upper cross-sectional dimension of the sprue model is smaller than the lower cross-sectional dimension of the sprue model; the minimum diameter dimension of the sprue model is at least 2-6 times the thickness of the ingrown model; the lower cross-sectional dimension of the sprue model is smaller than the cross-sectional dimension of the filter mesh model, and the lower edge of the sprue model is 2-10 mm away from the edge of the filter mesh model.

4. The casting process model according to claim 1, characterized in that: In the height direction of the filter mesh model, the portion arranged on the lower mold is larger than the portion arranged on the upper mold.

5. The casting process model according to claim 1, characterized in that: The runner model includes a plurality of bending parts, bending parts with different extension directions and high trapezoidal cross sections. The plurality of bending parts of the runner model are connected end to end, and the angle between the side walls corresponding to the adjacent bending parts is 60°-150°. The runner model includes: a first bending part, which is arranged in the lower mold and connected to the filter mesh model of the lower mold; a second bending part, which is arranged in the upper mold and connected to the first bending part, and the angle between the first and second bending parts is 60°-150°; a third bending part, which is arranged in the upper mold and connected to the second bending part, and the angle between the second and third bending parts is 100°-150°; a fourth bending part, which is arranged in the upper mold and connected to the third bending part, and the angle between the fourth bending part and the second bending part is 60°-150°; a fifth bending part, which is arranged in the upper mold and connected to the fourth bending part, and the angle between the fourth bending part and the fifth bending part is 60°-150°. The cross section of the runner model is a high trapezoid, and the height dimension of the high trapezoid is 1.5-10 times the average width dimension. The average width dimension of the cross section of the runner model is 1.5-5 times the thickness dimension of the ingrate model.

6. The casting process model according to claim 1, characterized in that: The width of the cross section of the ingrate model is at least 2-10 times the thickness of the ingrate model, and the thickness of the ingrate model is 0.4-0.8 times the thickness of the casting part connected to the ingrate model. The ingrate model is connected to the side and lower part of the runner model.

7. The casting process model according to claim 1, characterized in that: The riser neck model is located on the top surface of the casting. The riser body model is above the riser neck model, the minimum width dimension of the riser body model is at least 2-5 times the maximum thickness dimension of the casting model, and the height dimension of the riser body model is 1-2 times the minimum width dimension of the riser body model. The V-groove model is located on the top of the riser body, the length direction of the V-groove runs through the diameter direction of the riser body model, the cross-sectional width dimension of the V-groove model is 1 / 2-1 / 5 of the minimum diameter dimension of the riser body model, the cross-sectional height dimension of the V-groove model is 0.5-2 times the maximum cross-sectional width dimension of the V-groove model, and the slope of the inclined surface of the V-groove is 20-45 degrees.

8. A green sand casting process for thick ductile iron castings, characterized in that: include: S100, placing the casting process model according to any one of claims 1 to 7 in a sand box, and then filling the sand box with sand and compacting the sand; S200, after taking the casting process model, a sand mold with a mold cavity in the shape of the model is obtained, molten iron is poured from the pouring cup of the sand mold until the molten iron fills the riser body, and then cooled to obtain a cooling piece, and the riser part and the runner part on the cooling piece are cut off to obtain a casting; In the above S200, when the casting liquid is stopped from being injected into the sand mold, the pouring cup is kept in a full cup state.

9. The casting process according to claim 8, characterized in that: The compaction pressure in S100 is 100-120 N / cm 2 The pouring temperature of the molten iron in S200 is 1300-1360° C., and the components of the molten iron include 3.5-3.6wt% C and 2.3-2.5wt% Si.

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