Method for preventing evaporative pattern casting blind hole crush

Abstract

The invention discloses a method for preventing evaporative pattern casting blind hole crush, which comprises steps of: putting dry sand of a sand box which is compacted into an evaporative pattern mould of a blind hole, horizontally putting a member into the evaporative pattern mould with horizontal blind holes and inclined blind holes and near to the lower part; adding dry sand to an extraction end member and compacting dry sand; putting a layer of dry sand in the mould with vertical blind holes, simultaneously putting an I-shaped member, and then adding and compacting dry sand till the whole evaporative pattern blind holes is externally and internally filled with dry sand; leaving a white foam straight pouring gate between the evaporative pattern mould and the top surface of the dry sand; sealing the top of the dry sand of the sand box with a plastic film, laying a water pouring cup, opening a vacuum pump to cause the negative value to reach technology required value and casting, finally obtaining formed blind hole casting. The practical problem of the evaporative pattern casting blind hole crush is completely solved by putting the member or the I-shaped member with supporting or hanging type sand function into the evaporative pattern casting blind hole. The method is suitable for blind hole casting processing of deeper large-scale members.

Description

technical field [0001] The invention relates to smelting and casting technology, in particular to a method for preventing blind hole collapse of lost foam casting. Background technique [0002] At present, usually in the production of lost foam casting, for castings with blind hole structure of lost foam casting, the box collapse phenomenon is prone to occur, causing the castings to be scrapped. Especially when there are large and deep blind holes, it is often difficult to complete them with the lost foam process. The main reason for the collapse of the box is: after the molten metal vaporizes the foam, the molten metal has not had time to fill the space originally occupied by the foam in the lower part of the blind hole. In the blind hole area, the instantaneous value of the dry sand negative pressure in the blind hole changes from the static normal value of -0.05Mpa to about -0.03Mpa: the dry sand in the blind hole depends on the friction force and foam generated by the n...

AI Technical Summary

Problems solved by technology

[0004] 1. Changing the negative pressure value to -0.07Mpa has a certain effect on some castings, but it is not reliable for large and deep blind holes

On the other hand, the negative effect of increasing the negative pressure value is the damage of the paint layer, and the possibility of sand sticking increases.

[0005] 2. The hose is buried in the blind hole dry sand and connected to the negative pressure pipeline. Not only is the operation troublesome, but the effect is not satisfactory, and the problem of box collapse cannot be eliminated.

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