Lost Foam Negative Pressure Combustion The empty shell casting method refers to pouring the riser under the dry sand under negative pressure to ignite the foam and deliver a small amount of oxygen. The foam inside the mold is the rapid combustion that is generated deep, and the flue gas is vacuumed. After being pumped away and purified, the outer row is discharged, and after the shell is fired, the high-temperature metal liquid is poured, thereby obtaining a fine casting having no carbon defect or substantially no carbon defect.
This process was first announced to the foundry industry at home and abroad in Guilin in October 2008 and was publicly demonstrated and promoted. This method was called “Guilin No. 5 Empty Shell Casting Methodâ€. However, due to the different technical parameters of various casting production processes, the conventional packing film covers the vacuum sand box process, which makes it easy to burn out the gas around the riser, and the vacuum in the cavity drops rapidly after the pattern is fired. As a result, the external pressure of the cavity is much larger than the internal pressure, which is easy to cause collapse.
Therefore, the negative pressure value selected before casting is required to be 0.7 MPa or more. However, the excessively high degree of vacuum brings a series of problems to the pouring of molten iron, which may cause serious collapse of the collapsed tank or the gas slag hole, and also makes it difficult to control the negative pressure value in the range of 0.25-0.50 MPa according to the production experience before pouring. In order to overcome the above problems, it is necessary to change the conventional boxing plastic film covering vacuum sand box process method, and the technical difficulty of the "disappearing mold shell casting method" is extremely easy to collapse.
The specific content is divided into three aspects:
1. Description of the lost shell empty shell casting method
2. Advantages and Disadvantages of Lost Foam Shell Casting Process
3. Measures to solve the problem of lost mold hollow shell casting collapsed box
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