Exhaust structure of a ductile iron casting core

Abstract

The utility model discloses a nodular cast iron piece core exhaust structure, is equipped with a plurality of gas eye needle on the core, and sets up the fire line of blocking around the gas eye needle. The gas eye needle is arranged at the high point position of the core head of the inner gate far end. The nodular cast iron piece is the shell structure, and the wall thickness is thin and the shape is complex, and still distribute a plurality of oil channels. The utility model reasonably designs the position layout of gas eye needle, the size and quantity of gas eye needle, and thoroughly solves the nodular cast iron piece because of the exhaust, the gas hole class casting defect problem of producing gas hole of stifled breath.

Description

Technical Field

[0001] This utility model belongs to the field of ductile iron manufacturing, specifically relating to a venting structure for ductile iron cores. Background Technology

[0002] The original design for the integrated transmission system housing casting was as follows: This product is a ductile iron casting, molded using resin sand. Firstly, to ensure dimensional accuracy, cores No. 1 and No. 2 were placed inside the cavity of the lower mold body, using coated sand. Coated sand has characteristics such as high strength, good collapsibility, low gas generation, and good anti-sand adhesion, resulting in castings with complete shapes and smooth surfaces, thus ensuring the surface quality and dimensional accuracy of the casting. Secondly, to ensure internal quality, risers were installed in areas prone to shrinkage cavities due to heat dispersion. The gating system was positioned away from the oil passages, entering through the risers, effectively improving the riser's feeding capacity. Keeping the oil passages away from the gating system prevents overheating at the oil passages, reducing the tendency for shrinkage cavities and porosity. External chills were placed next to the oil passages to balance wall thickness differences and open feeding channels, achieving sequential solidification and obtaining sound internal quality. Thirdly, to improve the product's pass rate and stability, cores No. 3, No. 4, No. 5, and No. 6 are made of resin sand. Resin sand has good fluidity, is easy to compact, has an adjustable demolding time, high strength after hardening, and does not deform during handling and box assembly. This solution is lacking in venting considerations, only setting two oval risers in the upper box, and setting three vent holes on each of the two oval risers. However, these two vent holes only vent the cavity of the casting and cannot completely remove the gas. This product has a large number of cores during casting, and several cores will be stacked together. Therefore, the venting problem must be solved, otherwise, there will be casting defects such as porosity caused by trapped air and poor venting in the casting. Utility Model Content

[0003] This utility model provides a venting structure for the core of ductile iron parts. The technical problem to be solved is to address the casting defects such as porosity caused by poor venting and air entrapment in ductile iron parts.

[0004] To solve the above technical problems, this utility model provides a venting structure for a ductile iron core, characterized in that: multiple air holes are provided on the core, and fire-stopping lines are set around the air holes.

[0005] The air-hole needle is positioned at the high point of the core head at the far end of the ingate.

[0006] Ductile iron parts have a shell structure with thin walls and complex shapes, and also have several oil channels.

[0007] cross-sectional area F of the air-hole needle 气 The size is:

[0008] F 内:F 气 =1:(1.5-2.5);

[0009] F 内 This refers to the total cross-sectional area of ​​the ingate in the process of ductile iron castings.

[0010] Beneficial effects: The present invention has a reasonable design for the position, size and number of air holes, which can be applied to other ductile iron castings. Attached Figure Description

[0011] Figure 1 Diagram of the location of the air-eye needle

[0012] Figure 2 Schematic diagram of the fire-stop wire position on the N0.5 core

[0013] Figure 3 Schematic diagram of the fire-stopping wire position on the N0.6 core. Detailed Implementation

[0014] To make the purpose, content and advantages of this utility model clearer, the specific embodiments of this utility model will be described in further detail below.

[0015] This utility model proposes a venting structure for a ductile iron core. The ductile iron core is a shell structure with a thin wall and a complex shape, and it also has several oil passages. The oil passages need to be tested by oil pressure.

[0016] Casting venting is divided into cavity venting and core venting. Cavity venting usually involves setting two oval risers in the upper mold box, and setting multiple venting holes on the two oval risers respectively.

[0017] The innovation of this utility model lies in how to set a core venting structure based on the shell of the ductile iron part, with an air hole needle 1 on the core and a fire-stopping line 2 around the air hole needle;

[0018] The location of the venting pin should be determined according to the cavity venting setup. The venting pin should be placed at the highest point of the core head at the far end of the ingate. To prevent molten iron from encasing the core at the venting location, a fire-stopping line should be installed around the venting pin.

[0019] Total cross-sectional area F of the inlet runner in the shell process 内 Approximately 1200mm 2 The size of the air vent needle is determined based on the total cross-sectional area of ​​the ingate, and the cross-sectional area F of the air vent needle is set accordingly. 气 Size; F 内 :F 气 =1:(1.5-2.5);

[0020] Preferably, air vents are provided on the resin sand No.5 and No.6 cores. These two cores are cover cores that do not contact the casting, so they can better vent the sand cores.

[0021] Example 1:

[0022] Seven Ф10 vent pins are installed on the N0.5 core, and four Ф10 vent pins are installed on the N0.6 core. The original process used two oval risers in the upper mold box, with three Ф10 vent holes on each riser. This calculates that the cross-sectional area of ​​the vent pins is 1.11 times the cross-sectional area of ​​the ingate, i.e., F... 内 :F 气 =1:1.11. The final casting was not ideal and still had porosity defects.

[0023] Example 2:

[0024] Seven Ф20 vent pins are installed on the N0.5 core, and four Ф20 vent pins are installed on the N0.6 core. The original process used two oval risers in the upper mold box, with three Ф10 vent holes on each riser. This calculates that the cross-sectional area of ​​the vent pins is 3.27 times the cross-sectional area of ​​the ingate, i.e., F... 内 :F 气 =1:3.27. The final casting was not ideal and still had a small number of porosity defects.

[0025] Example 3:

[0026] Seven Ф15 vent pins are installed on the N0.5 core, and four Ф15 vent pins are installed on the N0.6 core. The original process used two oval risers in the upper mold box, with three Ф10 vent holes on each riser. This calculates that the cross-sectional area of ​​the vent pins is 2.01 times the cross-sectional area of ​​the ingate, i.e., F... 内 :F 气 = 1:2.01. The final casting surface had no porosity or other casting defects.

[0027] The final solution is to vent the core. The vent needle should be placed at the highest point of the core head at the far end of the ingate. To prevent the molten iron from encasing the core at the venting position, a fire-stopping line should be set around the vent needle. Generally, the cross-sectional area of ​​the vent needle should be slightly more than twice the cross-sectional area of ​​the ingate.

[0028] Because during the casting process, not only does gas tend to accumulate at the location of the air hole needle, slag also tends to accumulate around the air hole needle. Therefore, air hole needles should be avoided on castings as much as possible.

[0029] This invention adds an venting system to the existing process, incorporating core venting. The core vent needle should be positioned as high as possible at the far end of the core head of the ingate. To prevent molten iron from encasing the core at the venting location, a fire-stopping line should be installed around the vent needle. Generally, the cross-sectional area of ​​the vent needle should be slightly more than twice the cross-sectional area of ​​the ingate. This results in castings with no porosity defects on the surface.

[0030] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A venting structure for a ductile iron core, characterized in that: Multiple air holes are provided on the core, and fire-stopping wires are set around the air holes.

2. The venting structure for a ductile iron core according to claim 1, characterized in that: The air-hole needle is positioned at the high point of the core head at the far end of the ingate.

3. The venting structure for a ductile iron core according to claim 1, characterized in that: Ductile iron parts have a shell structure with thin walls and complex shapes, and also have several oil channels.

4. A venting structure for a ductile iron core according to any one of claims 1-3, characterized in that: cross-sectional area F of the air-hole needle 气 The size is: F 内 :F 气 =1:(1.5-2.5); F 内 This refers to the total cross-sectional area of ​​the ingate in the process of ductile iron castings.

5. The venting structure for a ductile iron core according to claim 4, characterized in that: F 内 :F 气 =1:2.01。

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