Casting long and thin hole forming sand core structure

Abstract

The invention discloses a casting long and thin hole forming sand core structure. End portion fireproof casing pipes, a transition fireproof casing pipe, a process steel pipe, a casing pipe bonding resin layer, an outer sand core layer, an inner sand core layer and end face sealing layers are included. The transition fireproof casing pipe is arranged between the end portion fireproof casing pipes,the transition fireproof casing pipe and the end portion fireproof casing pipes are in butt joint through the casing pipe bonding resin layer to form a hollow fireproof casing pipe. The process steelpipe is coaxially arranged in an inner hole of the fireproof casing pipe. A ventilation hole is formed in a pipe body of the process steel pipe. The outer sand core layer is arranged between an innerhole of the process steel pipe and the inner hole of the fireproof casing pipe. The inner sand core layer is arranged in the inner hole of the process steel pipe. The end face sealing layers are arranged at the two ends of the outer sand core layer. An air outlet channel is arranged at the center of the inner sand core layer. According to a long and thin casting hole sand core of the structure, the defects that an ordinary sand core is low in surface fireproof degree and is prone to burning losses, burning through, washing damage or washing fracture through high-temperature molten iron can beeliminated, sand discharging and process steel pipe recycling and repeated usage are facilitated, the sand usage amount is small, and the casting cost is low.

Description

technical field [0001] The invention belongs to the technical field of casting, and in particular relates to a casting sand core structure with elongated holes. Background technique [0002] Many castings are designed with slender straight hole structure, and the materials used to make cores in casting production are generally resin core sand, water glass core sand, clay core sand, oil core sand, etc., among which resin core sand is used most widely. Since the core is mostly surrounded by high-temperature molten metal in the mold, defects such as seepage, sand sticking, pores, and deformation are prone to occur in the holes of the casting. High refractoriness, strength, rigidity and air permeability, retreat and collapse. [0003] In order to improve the refractoriness, strength, rigidity and air permeability of the sand core, the following two schemes are mainly adopted at present: [0004] The first one is to select a seamless steel pipe whose inner diameter is consiste...

AI Technical Summary

Problems solved by technology

When using seamless steel pipes to insert castings for casting, there may be gaps between the steel pipes and the castings, which is not suitable for castings with high performance requirements, and it is required that the steel pipes and molten metal are well welded but not melted

However, the slender casting hole of the casting often has large wall thickness, large thermal joints, and poor heat dissipation conditions. Especially in the liquid state of high-temperature molten metal for a long time, not only the steel pipe is melted, but also the surface of the core sand in the tube is melted, causing the casting hole to be biased. Leakage and sticky sand in pipes and tubes cannot be cleaned up, resulting in scrapping of castings

In addition, due to improper surface treatment of steel pipes or contamination, pore defects are prone to occur, and steel pipes need to be derusted and dried or coated and cannot be recycled, so the cost is high

[0005] Second, resin core sand is used, and steel pipe bones with vent holes on the inner wall are placed in the core box. The original sand uses special sand with high refractoriness such as chromite sand, pearl sand, etc., so as to ensure the refractoriness and strength of the sand core. , rigidity, and air permeability, while special raw sand is expensive and the cost of castings is high

[0008] Although this solution solves the insufficient compactness of the sand core in the prior art, it cannot effectively exhaust air, and sand sticking and pores are very easy to occur, making it difficult to reduce the manufacturing cost of castings.

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