Narrow-groove long hole lost-foam casting method

Abstract

The invention discloses a narrow-groove long hole lost-foam casting method applied to the field of casting. The lost-foam casting method comprises the following steps that a dried flour core with a carbonized surface is inserted into a narrow slit or a long hole in a white mold block, and is bonded and sealed through using lost-foam glue, wherein the flour core is composed of flour and iron sand or steel shots, the flour accounts for 10%-25% of the weight of the iron sand or the steel shots, the flour core can also be composed of the flour and sand grains, and the flour accounts for 1 / 5-1 / 2 ofthe weight of the sand grains; a flour mixture is uniformly mixed and kneaded with water, and extrusion molding is performed with a core mold; the flour core is dried and carbonized in the core moldin an anoxic environment, wherein the drying temperature is 60 DEG C-90 DEG C, the drying time is 1 h-2 h, the carbonization temperature is 150 DEG C-200 DEG C, and the carbonization time is 15 min-30min; and in order to improve the strength of the flour core, a core bar is placed in the flour core, and the flour core is easy to scatter and convenient to clean. According to the method, a narrow-groove or long-hole casting with a smooth surface can be obtained, scribing machining is avoided, and the metal yield and the product percent of pass are increased.

Description

technical field [0001] The invention is applied in the field of lost foam casting, and is suitable for casting narrow slots and long holes of iron and steel castings. Background technique [0002] In the field of casting, for the structure of holes, seams, and cavities of castings, the method of casting is generally adopted to form the core, and the sand core is mostly made of resin sand with good collapsibility. However, for castings with long holes and narrow groove structures, when the hole depth and aperture ratio H / d of the through hole, the groove depth or the ratio of length to width of the narrow groove are greater than or equal to 5, due to the long hole, narrow It is not easy to paint the inside of the groove, or even if it can be painted, the molding sand is not easy to fill, or the mold is poorly filled, making it difficult to cast long holes and narrow grooves, so the only way is to use the sand core. Due to the extremely poor heat dissipation conditions of the...

AI Technical Summary

Problems solved by technology

However, for castings with long holes and narrow groove structures, when the hole depth and aperture ratio H / d of the through hole, the groove depth or the ratio of length to width of the narrow groove are greater than or equal to 5, due to the long hole, narrow The inside of the tank is not easy to paint, or even if it can be painted, the molding sand is not easy to fill, or the filling is poor, making it difficult to cast long holes and narrow grooves, so the only way to use the sand core

Due to the extremely poor heat dissipation conditions of the sand core in the long hole and narrow groove, quartz sand will form a variety of homogeneous crystals at different temperatures, and the volume changes greatly. Influenced by physical and chemical effects such as wettability, it is often difficult to clean the sand core after the casting is overturned. Even if the sand core is cleaned, the surface quality of the narrow groove and long hole is very poor and not smooth, which will affect the use or cause waste in severe cases.

Especially for slots and holes with a size less than 6mm, only machining methods can be used, and lost foam casting methods cannot be used for direct casting.

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