Process for preventing metal nodular cast iron lightening hole from shrinkage porosity

Abstract

The invention discloses a process for preventing the shrinkage porosity of a lightening hole of a metal nodular cast iron, which comprises the following steps of: a, normally burying sand in a main mold, and reserving a pipeline in the process; b, after the sand box is turned over, a pouring gate is connected to a pouring cup; c, a second paper pipeline is connected and led out of the sand box to be flush with the pouring cup; d, a foam taper sleeve is installed on the first paper pipeline; e, sealing an upper port of the foam taper sleeve by using an adhesive tape to prevent casting sand from entering; and f, the whole foam taper sleeve is buried in the sand box. The second paper pipeline is installed to assist in discharging gas generated by foam combustion, so that the feeding effect is achieved when the gas is cooled and solidified.

Description

Technical Field

[0001] The invention relates to the technical field of cast iron processing, in particular to a process for preventing shrinkage of weight loss holes in ductile iron molds. Background Art

[0002] Ductile iron, the material used in automotive stamping dies, is high in alloy content. This makes it prone to shrinkage defects after molten iron pouring, particularly where the shape changes dramatically and at the intersection of ribs and plates. Shrinkage is particularly common in smaller molds. Furthermore, lightening holes on the non-machined surfaces of the mold are located closer to the intersection of ribs due to the smaller internal cavity, making them more susceptible to visible shrinkage.

[0003] Traditionally, shrinkage has been addressed through the use of direct or indirect chillers, either to transfer the shrinkage or to prevent it from becoming visible after processing. Because automotive stamping dies and castings vary in usage, chillers must be custom-made and disposable, significantly increasing production and manufacturing costs. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned problems and to propose a process for preventing shrinkage of weight loss holes in ductile iron molds.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: comprising the following steps:

[0006] a. The main mold is buried in sand normally, and pipelines are reserved during the process;

[0007] b. After the sand box is turned over, connect the pouring channel to the pouring cup;

[0008] c. Connect the second paper pipe and lead it outside the sand box, flush with the pouring cup;

[0009] d. Install the foam cone sleeve onto the first paper pipe;

[0010] e. The upper port of the foam cone sleeve is sealed with tape to prevent the ingress of foundry sand;

[0011] f. The foam cone sleeve is completely buried inside the sand box.

[0012] Specific implementation methods and effects:

[0013] The four corners of the casting are close to the edge of the sand mold and have relatively less heat, so the cooling and solidification are faster. A second paper pipe is installed to assist in the discharge of the gas from the foam combustion, thereby playing a role in shrinkage compensation during cooling and solidification.

[0014] The middle of the casting is far away from the edge of the sand mold and the heat is more concentrated, so the cooling and solidification are slow. The first paper pipe and foam cone sleeve are installed to increase the shrinkage feeding effect when the molten iron is cooling and solidifying;

[0015] The foam cone sleeve is completely buried in the sand box to reduce the cooling and solidification speed and improve the shrinkage compensation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of pipeline installation for a process proposed by the present invention to prevent shrinkage of weight loss holes in ductile iron molds.

[0017] In the figure: 1, first paper pipe; 2, second paper pipe; 3, foam cone sleeve; 301, port; 4, runner. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0020] Reference Figure 1 A process for preventing shrinkage of ductile iron due to weight loss in a mold, comprising the following steps:

[0021] a. The main mold is buried in sand normally, and pipelines are reserved during the process;

[0022] b. After the sand box is turned over, connect the pouring channel 4 to the pouring cup;

[0023] c. Connect the second paper pipe 2 and lead it outside the sand box, flush with the pouring cup;

[0024] d. Install the foam cone sleeve 3 onto the first paper pipe 1;

[0025] e. The upper port 301 of the foam cone sleeve 3 is sealed with tape to prevent the entry of casting sand;

[0026] f. The foam cone sleeve 3 is entirely buried inside the sand box.

[0027] Specific implementation methods and effects:

[0028] The four corners of the casting are close to the edge of the sand mold and have relatively less heat, so the cooling and solidification are faster. A second paper pipe 2 is installed to assist in the discharge of gas from the foam combustion; during cooling and solidification, it plays a role in shrinkage compensation.

[0029] The middle part of the casting is far away from the edge of the sand mold and the heat is more concentrated, so the cooling and solidification are slow. The first paper pipe 1 and the foam cone sleeve 3 are installed to increase the shrinkage feeding effect when the molten iron is cooling and solidifying;

[0030] The foam cone sleeve 3 is entirely buried in the sand box to reduce the cooling and solidification speed and improve the shrinkage feeding effect.

[0031] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A process for preventing shrinkage of ductile iron mold weight loss holes, characterized in that: The following steps are involved: a. The main mold is buried in sand normally, and pipelines are reserved during the process; b. After the sand box is turned over, connect the pouring channel (4) to the pouring cup; c. Connect the second paper pipe (2) and lead it outside the sand box, flush with the pouring cup; d. Installing a foam cone sleeve (3) onto the first paper pipe (1); e. The upper port (301) of the foam cone sleeve (3) is sealed with tape to prevent the entry of casting sand; f. The foam cone sleeve (3) is entirely buried inside the sand box.

2. A process for preventing shrinkage of weight loss holes in ductile iron molds according to claim 1, characterized in that: Specific effects: The four corners of casting A are close to the edge of the sand mold and have relatively less heat, so they cool and solidify faster. A second paper pipe (2) is installed to assist in the discharge of gas from the combustion of the foam; B. The middle part of the casting is far away from the edge of the sand mold and the heat is more concentrated, and the cooling and solidification are slow. The first paper pipe (1) and the foam cone sleeve (3) are installed to increase the shrinkage feeding effect when the molten iron is cooled and solidified; C. The foam cone sleeve (3) is entirely buried in the sand box to reduce the cooling and solidification speed.

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