Preparation process of high-performance precoated sand for complex casting and compression molding system thereof

A high-performance, coated sand technology, used in foundry molding equipment, molds, manufacturing tools, etc., can solve problems such as casting cracks, strength and thermal stability cannot meet requirements, and achieve toughness enhancement and reduce crosslinking density. Effect

Active Publication Date: 2020-12-29
济南市平阴县玛钢厂
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the coated sand produced by the traditional method is used in the casting to produce these high-precision castings,

Method used

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  • Preparation process of high-performance precoated sand for complex casting and compression molding system thereof
  • Preparation process of high-performance precoated sand for complex casting and compression molding system thereof
  • Preparation process of high-performance precoated sand for complex casting and compression molding system thereof

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preparation example Construction

[0038] A method for preparing high-performance coated sand for complex castings comprises the following steps:

[0039] Heat the raw sand to 100-150°C, place it in a sand mixer, add bisphenol A epoxy resin modified phenolic resin, modified coupling agent in turn, stir and mix for 0.2-1 hour, cool down to 20-50°C, Add hexamethylenetetramine and ethyl acetate, mix, freeze, pulverize, and sieve to obtain high-performance coated sand for complex castings;

[0040] The modified coupling agent is composed of silane coupling agent and aluminum chloride according to the mass ratio of 10-15:1-3; adding aluminum chloride to the silane coupling agent, aluminum chloride can be mixed with the silane coupling agent Nitrogen atoms and oxygen atoms are chelated, and the resulting chelates can improve the strength, wear resistance and flex resistance of the coated sand.

[0041] Among them, the mass ratio of raw sand, bisphenol A epoxy resin modified phenolic resin, modified coupling agent, h...

Embodiment 1

[0054] A high-performance coated sand for complex castings is prepared according to the following steps:

[0055] ①Add 100kg of phenol, 85kg of formaldehyde, and 5kg of oxalic acid into the reactor, heat to 60°C and stir for 4 hours. When the free aldehyde content is less than 1.5%, distill and dehydrate. When the temperature in the reactor rises to 140°C, turn on the vacuum , continue distillation and dehydration for 1 hour, add bisphenol A epoxy resin 1kg and nitrile rubber 10kg, stir for 0.1 hour, get bisphenol A epoxy resin modified phenolic resin;

[0056] ②Heat 100kg of raw sand to 100°C, put it in a sand mixer, add 5kg of bisphenol A epoxy resin modified phenolic resin, 0.05kg of modified coupling agent, stir and mix for 0.2 hours, cool down to 20°C, add 0.5kg of hexamethylenetetramine, 1kg of ethyl acetate, mixed, frozen, pulverized, and sieved to obtain high-performance coated sand for complex castings;

[0057] The modified coupling agent is composed of 3-aminopropy...

Embodiment 2

[0063] A high-performance coated sand for complex castings is prepared according to the following steps:

[0064] ①Add 150kg of phenol, 135kg of formaldehyde, and 15kg of oxalic acid to the reactor, heat to 100°C and stir for 8 hours. When the free aldehyde content is less than 1.5%, distill and dehydrate. When the temperature in the reactor rises to 140°C, turn on the vacuum , continue distillation dehydration 3 hours, add bisphenol A epoxy resin 5kg and nitrile rubber 30kg, stir 0.5 hour, get bisphenol A epoxy resin modified phenolic resin;

[0065] ②Heat 120kg of raw sand to 150°C, place it in a sand mixer, add 15kg of bisphenol A epoxy resin modified phenolic resin, 0.2kg of modified coupling agent, stir and mix for 1 hour, cool down to 50°C, add 2.5kg of hexamethylenetetramine, 4kg of ethyl acetate, mixed, frozen, pulverized, and sieved to obtain high-performance coated sand for complex castings;

[0066] The modified coupling agent is composed of 3-(2-aminoethyl)-aminop...

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Abstract

The invention discloses a high-performance precoated sand for complex castings and a compression molding system thereof. According to the high-performance precoated sand for the complex castings and the compression molding system thereof, a binder is bisphenol A epoxy resin modified phenolic resin, meanwhile, nitrile rubber is added, the mechanical property, the bonding strength and the thermal stability of the obtained modified phenolic resin are greatly improved, and the dimensional stability of a cured product is excellent; the precoated sand prepared from the phenolic resin is high in strength and excellent in thermal stability, and when the sand is used for casting a high-precision casting with a complex structure, due to the high strength, the thermal stability and the dimensional stability, thermal stress generated by sand core expansion can be resisted, and casting cracks are prevented from being generated; montmorillonite, calcium stearate and alkali-free glass fibers are usedas a composite collapsing agent, so that the collapsibility, gas evolution, strength and thermal toughness of the precoated sand are remarkably improved, the compactness of the sand core is improved,the strength of a mold core is improved, and the casting is prevented from deforming and cracking; and in addition, the compression molding system utilizes sand mold preheating to preheat the precoated sand, so that the precoated sand is easier to press.

Description

technical field [0001] The invention relates to the technical field of casting coated sand, in particular to a preparation process of high-performance coated sand for complex castings and a pressing molding system thereof. Background technique [0002] Coated sand refers to molding sand or core sand with a layer of solid resin film on the surface, which is used for casting various metal castings. Usually, hard, wear-resistant and chemically stable quartz sand is used as the raw sand, and phenolic resin is used as the binder, and it is made of raw materials such as curing agent and lubricant. Because coated sand has the advantages of high strength and low gas generation, it can be used to cast various steel and iron castings with high precision and smooth surface. With the rapid development of the automobile industry and the technical needs of high-precision mechanical products, the quality and precision requirements of castings are gradually increasing, which puts forward h...

Claims

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Application Information

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IPC IPC(8): B22C1/22B22C5/00B22C5/16
CPCB22C1/2253B22C1/226B22C5/00B22C5/16
Inventor 张进军展康进张鑫豪
Owner 济南市平阴县玛钢厂
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