Riser-free and chilling block-free process structure of medium-large-sized nodular cast iron flywheels

Abstract

The utility model discloses a middle and large scale nodular cast iron flywheel riser-free and chilling block-free process structure, which comprises a flywheel casting horizontally arranged in the center of a sand box, the sand box is a cast steel sand box, a thick and large rim part of the flywheel casting is distributed on a lower box of the sand box, and a sprue is arranged on the outer side of the flywheel casting. The lower portion of the straight pouring gate is symmetrically connected with an annular transverse pouring gate arranged around the periphery of the flywheel casting, a plurality of short flat inner pouring gates are evenly distributed between the annular transverse pouring gate and the flywheel casting, an overflow rod is arranged on the outer side, away from the straight pouring gate, of the flywheel casting, and the lower portion of the overflow rod is connected with the flywheel casting. Four overflow needles are evenly distributed on the periphery of the highest end face of a central plummer block of the flywheel casting, and overflow needles are evenly distributed in the middle of a rib plate of the flywheel casting at the interval of 120-170mm from the end face of a rim. By means of the characteristic of graphitization expansion self-feeding of ductile iron, casting defects such as shrinkage porosity and shrinkage cavities are eliminated, materials such as risers and chillers and labor cost are saved, the process yield is increased, and the surface quality of castings is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of ductile iron flywheel casting, in particular to a process structure of a medium-to-large ductile iron flywheel without a riser and a chiller. Background Art

[0002] The flywheel is an important component of a diesel generator, and its material and internal quality requirements are high, especially the stress-bearing part connected to the crankshaft is not allowed to have shrinkage defects. The flywheel material is mostly QT400-12 to QT600-3. Since ductile iron is a eutectic or hypereutectic component, its paste-like solidification method makes the casting shell unable to resist graphitization expansion, the casting wall migration occurs, the casting volume increases, and it is very easy to produce internal shrinkage and shrinkage defects. Please refer to Figure 4 Therefore, most ductile iron flywheels use universal risers or heating risers at the highest point of the casting with special conformal chillers at the bottom to ensure the sequential solidification of the casting and eliminate casting defects such as shrinkage and shrinkage cavities.

[0003] The flywheel uses a universal riser or a heating riser and a special chiller process, which has the following disadvantages: 1. The material cost is increased, especially the heating riser is expensive, and the special form-fitting chiller needs to be cast in advance; 2. The process yield is reduced, and the riser and special chiller increase the weight of the box liquid; 3. The riser and special chiller are placed manually during molding, which reduces the molding production efficiency; 4. Cleaning and removing the riser, grinding the riser neck and chiller marks, reduces the efficiency of cleaning the casting; 5. The riser neck and chiller marks affect the appearance quality of the casting after grinding, and reduce the surface quality of the casting. Utility Model Content

[0004] The utility model aims to provide a process structure of a medium-to-large ductile iron flywheel without a riser and a chiller, which can reduce material costs and improve production efficiency.

[0005] The technical scheme adopted by the utility model is: a process structure of a medium-to-large ductile iron flywheel without a riser and a chiller, comprising a flywheel casting which is centrally placed flat in a sand box, the sand box adopts a cast steel sand box, the thick and large wheel rim part of the flywheel casting is distributed in the lower box of the sand box, a straight runner is arranged on the outer side of the flywheel casting, the lower part of the straight runner is symmetrically connected to an annular cross runner arranged around the outer periphery of the flywheel casting, a plurality of short flat inner runners are evenly distributed between the annular cross runner and the flywheel casting, an overflow rod is arranged on the outer side of the flywheel casting away from the straight runner, the lower part of the overflow rod is connected to the flywheel casting, four overflow needles are evenly distributed around the highest end surface of the central axis platform of the flywheel casting, and overflow needles are evenly distributed around the middle of the rib plate of the flywheel casting and the wheel rim end surface at an interval of 120-170mm.

[0006] Furthermore, the lower end diameter of the overflow rod is 100 mm, and the single-side draft angle is controlled within 10 mm.

[0007] Furthermore, the overflow needle has a top diameter of 8 mm and a bottom diameter of 14 mm.

[0008] Furthermore, the angle between the end sides of the annular cross runners on both sides away from the straight runner and the line connecting the center of the flywheel casting is less than 90°.

[0009] Furthermore, the length of the flat ingates is 20-25 mm, and the distance between the flat ingates is 130-160 mm.

[0010] The utility model has the following beneficial effects:

[0011] 1. Save the material costs of heating risers, special chillers, etc.

[0012] 2. The molding operation is quick and easy, and there is no need to manually place the riser and chiller, which improves the molding production efficiency;

[0013] 3. Improved process yield and saved material melting costs. The original process yield was about 60%, while the improved process yield was 78%, an increase of 18%.

[0014] 4. No need to clean and grind the riser and cold iron traces, which improves the cleaning production efficiency;

[0015] 5. The grinding marks on the casting surface are reduced, which improves the appearance quality of the casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the utility model;

[0017] Figure 2 It is a parting diagram of the utility model;

[0018] Figure 3 It is a top view of the utility model;

[0019] Figure 4 It is a structural schematic diagram of the prior art.

[0020] In the figure: 1. flywheel casting; 2. straight runner; 3. annular cross runner; 4. flat ingates; 5. overflow rod; 6. overflow needle; 7. cast steel sand box; 8. heating and insulation riser; 9. special chiller. DETAILED DESCRIPTION

[0021] In order to better understand the purpose, structure and function of the utility model, the following is a further detailed description of the process structure of a medium-to-large ductile iron flywheel without a riser and a chiller of the utility model in conjunction with the accompanying drawings.

[0022] like Figure 1~Figure 3As shown, a process structure of a medium-to-large ductile iron flywheel without a riser and a chiller comprises a flat flywheel casting 1, a thick rim portion of the flywheel casting 1 is distributed in the lower box of a sand box, a sprue 2 is arranged on the outer side of the flywheel casting 1, the lower part of the sprue 2 is symmetrically connected to an annular cross runner 3 arranged around the outer periphery of the flywheel casting 1, a plurality of short flat ingates 4 are evenly distributed between the annular cross runner 3 and the flywheel casting 1, an overflow rod 5 is arranged on the outer side of the flywheel casting 1 away from the sprue 2, the lower part of the overflow rod 5 is connected to the flywheel casting 1, four overflow needles 6 are evenly distributed around the highest end surface of the central axis platform of the flywheel casting 1, and a plurality of overflow needles 6 are evenly distributed around the middle of the rib plate of the flywheel casting 1 with an interval of 120-170 mm from the end surface of the rim.

[0023] The process structure of this embodiment is verified on a flywheel with an outer diameter of 700 mm, the material is QT600-3, and the modulus of the thickest part of the rim is about 2.9 cm, which meets the theoretical requirement of a riser-free process modulus of more than 2.5 cm.

[0024] The molding process is arranged as one mold and one piece, and the thick rim part of the flywheel casting 1 is distributed in the lower box of the sand box, and the thick part is in the lower mold, which is conducive to shrinkage compensation of the casting. The phenol urea resin self-hardening sand molding is adopted, and the cast steel sand box 7 is arranged evenly in the center. The mold rigidity is large, which can eliminate the mold wall displacement caused by graphitization expansion in the early stage of solidification of the casting. A lower pouring temperature can reduce liquid shrinkage. The volume of the molten iron expands immediately after entering the casting mold, avoiding liquid shrinkage defects.

[0025] like Figure 1 and Figure 4 As shown, in the pouring system, the process scheme of using the heating insulation riser 8 and the special cold iron 9 is cancelled, and the annular cross runner 3 is adopted, and multiple short and flat flat ingates 4 are evenly distributed and quickly dispersed into the molten iron, and the upper box is evenly overflowed, and there is no riser and no cold iron process structure. Among them, the angle between the end side of the annular cross runner 3 on both sides away from the straight runner 2 and the center line of the flywheel casting 1 is less than 90°, the length of the flat ingates 4 is 20~25mm, and the distance between the flat ingates 4 is 130-160mm. The lower end diameter of the overflow rod 5 is 100mm, the single-sided draft angle is controlled within 10mm, and the top diameter of the overflow needle 6 is 8mm, and the bottom diameter is 14mm.

[0026] By adopting the process structure of this embodiment, the characteristics of graphitization expansion of molten iron due to secondary contraction between austenite dendrites and eutectic groups of ductile iron are utilized in the late stage of solidification to achieve a high expansion internal pressure in a solid casting mold, thereby offsetting the micro-shrinkage caused by the secondary shrinkage and achieving the purpose of eliminating shrinkage defects of castings.

[0027] By adopting the process structure of this embodiment on medium and large ductile iron flywheels, the self-compensating property of graphitized expansion of ductile iron can be utilized to eliminate casting defects such as shrinkage and shrinkage cavities, save materials and labor costs such as risers and chills, increase the process yield, and improve the surface quality of castings.

[0028] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A process structure of a medium-to-large ductile iron flywheel without a riser and a chiller, characterized in that: The invention comprises a flywheel casting (1) centrally placed in a sand box, wherein the sand box is a cast steel sand box (7), a thick wheel rim portion of the flywheel casting (1) is distributed in the lower box of the sand box, a sprue (2) is arranged outside the flywheel casting (1), the lower part of the sprue (2) is symmetrically connected to an annular cross runner (3) arranged around the outer periphery of the flywheel casting (1), a plurality of short flat inner runners (4) are evenly distributed between the annular cross runner (3) and the flywheel casting (1), an overflow rod (5) is arranged outside the flywheel casting (1) away from the sprue (2), the lower part of the overflow rod (5) is connected to the flywheel casting (1), four overflow needles (6) are evenly distributed around the highest end surface of the central shaft platform of the flywheel casting (1), and overflow needles (6) are evenly distributed around the middle of the rib plate of the flywheel casting (1) and the wheel rim end surface at an interval of 120-170 mm.

2. The process structure of medium and large ductile iron flywheel without riser and chiller according to claim 1 is characterized in that: The lower end diameter of the overflow rod (5) is 100 mm, and the single-side draft angle is controlled within 10 mm.

3. The process structure of medium-to-large ductile iron flywheel without riser and chiller according to claim 1 or 2, characterized in that: The top diameter of the overflow needle (6) is 8 mm, and the bottom diameter is 14 mm.

4. The process structure of medium and large ductile iron flywheel without riser and chiller according to claim 1 is characterized in that: The angle between the end sides of the annular cross runners (3) on both sides away from the straight runner (2) and the line connecting the center of the flywheel casting (1) is less than 90 degrees.

5. The process structure of medium-to-large ductile iron flywheel without riser and chiller according to claim 1 or 4, characterized in that: The length of the flat ingates (4) is 20-25 mm, and the distance between the flat ingates (4) is 130-160 mm.

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