High-temperature-resistant easy-collapsibility precoated sand for casting

Abstract

The invention discloses high-temperature-resistant easy-collapsibility precoated sand for casting. The precoated sand comprises the following components in parts by weight: 97 to 98 parts of original sand, 2 to 2.5 parts of phenolic resin, 0.3 to 0.4 part of urotropine, 0.15 to 0.2 part of calcium stearate, and 0.1 to 0.3 part of anhydrous copper sulfate. The high-temperature-resistant easy-collapsibility precoated sand for casting is prepared by employing the specific components and content, especially, the contained anhydrous copper sulfate has high decomposition temperature which is required to be a high temperature of 650 DEG C or more; when a pouring temperature reaches 1400 DEG C, because the precoated sand is a poor heat conductor, the decomposition temperature is relatively appropriate, and the high temperature resistant performance and the poured collapsibility performance of the precoated sand can be guaranteed. At the same time, the invention also discloses a preparation method of the precoated sand. The method adopts specific steps and a charging sequence, and can quickly obtain the high-temperature-resistant easy-collapsibility precoated sand.

Description

technical field [0001] The invention relates to a coated sand used in the field of casting, in particular to a high temperature resistant coated sand for casting. Background technique [0002] Coated sand refers to the molding sand or core sand that is covered with a solid resin film on the surface of the sand grains before molding. There are two coating processes: cold method and hot method: the cold method dissolves the resin with ethanol, and adds urotropine during the sand mixing process, so that the two are coated on the surface of the sand, and the ethanol volatilizes to obtain coated sand; Preheat the sand to a certain temperature, add resin to melt, stir to coat the resin on the surface of the sand, add urotropine aqueous solution and lubricant, cool, crush, and sieve to obtain coated sand. For steel castings and iron castings. Due to the advantages of high strength, low gas generation, high dimensional accuracy of production castings, smooth surface and easy stora...

AI Technical Summary

Problems solved by technology

[0003] In the current casting process using coated sand as sand core, when the pouring temperature is 1400°C, high temperature resistant coated sand is usually used, and the biggest disadvantage of high temperature resistant coated sand is that it is very difficult to clean up later

In the existing market, there are products that use pyrolysis oxygen such as potassium permanganate as the disintegrating agent of coated sand, but because of its low decomposition temperature (at 200-300°C), it can only be used for non-ferrous casting (pouring temperature below 800°C) ), if it is used in cast iron process (pouring temperature is 800-1400 ℃), it will cause the collapsing agent to decompose oxygen and play a collapsing role before the pouring is completed, which will eventually cause the casting to be deformed or scrapped