A kind of lost foam of stmma large-size solid casting plate and its preparation method

Abstract

The invention discloses an STMMA large-size solid casting plate lost mold and a preparation method thereof. Including the process steps of bead selection, pre-foaming, drying and aging, molding, cooling, demoulding and plate drying, the invention can solve defects such as carbon black on the surface of ductile iron parts after casting, and can effectively reduce the amount of gas generated to avoid Back spraying occurs during pouring to prevent the deformation of the STMMA lost pattern produced, improve the bonding strength between beads, ensure the full fusion of beads, improve the structural strength of castings, and achieve the goal of saving raw materials, reducing costs and environmental protection The effect, and the yield of castings is greatly improved; the comprehensive production cost of castings is further reduced.

Description

technical field [0001] The invention belongs to the field of casting technology, in particular to a large-size STMMA solid cast plate lost foam and a preparation method thereof, and is especially suitable for the preparation of STMMA lost foam patterns for ductile iron. Background technique [0002] The lost foam casting technology is to bond and combine foamed plastic models similar in size and shape to the castings to form a model cluster. After brushing with a refractory coating and drying, it is buried in dry quartz sand for vibration molding, and liquid metal is poured under certain conditions. The method of vaporizing the model and occupying the position of the model, solidifying and cooling to form the required casting. Compared with traditional casting technology, lost foam casting uses foam materials (EPS, EPMMA, STMMA and STMMA-FD) that are easily gasified at high temperatures as patterns, without sand cores, non-bonded dry sand, non-fitting boxes, It does not tak...

AI Technical Summary

Problems solved by technology

Due to the advantages of low price, low gas generation, and easy forming of EPS, the pattern material used by most foundries is generally EPS to produce ductile iron castings, but this material has a relatively high carbon content (up to 92%). And the molecular formula contains a carbon-rich benzene ring structure, which is relatively stable in thermodynamics, so it is not easy to thermally decompose. When the temperature is higher than 900 ° C, EPS is thermally decomposed to form a tar-like viscous liquid, which is further decomposed into carbon and hydrogen. Cracking is carried out in the way of disorderly fracture, so it is easy to produce carbon black on the castings when producing ductile iron, and the castings are prone to defects such as slag inclusions, which will reduce the quality of the castings or even scrap them

EPMMA is a polymer with a straight-chain structure. When it is thermally decomposed, it will be cracked in a rapid way. The use of EPMMA is very effective in solving defects such as carbon black on the surface of ductile iron castings, but the gas generation of EPMMA is about that of EPS. 1.5 times, it is easy to cause back spray when pouring

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