How to improve the uneven compactness of sand mold caused by high mold products?

In actual work, when the Automatic Molding Machine produces some high-quality sand molds, the product often has uneven compactness, and even cannot be molded. The main reasons for such anomalies are as follows:

1. For the full-automatic molding machine with side shot sanding method, the sand shot direction is perpendicular to the mold, and the high mold is easy to block the shot sand and form a shadow surface on its back, and the distribution of the molding sand is less, resulting in the compaction rate of the molding sand after compaction uneven;

2. For the full-automatic molding machine with side shot sand method, the fluidity of the molding sand is insufficient. If the moisture content of the molding sand is too high and the mud content is too high, it will bond into agglomerates, and the kinetic energy speed will decrease while the mass increases. It is more difficult to climb mountains and mountains with high molds, resulting in uneven filling and uneven compaction after compaction;

3. Even if it is a fully automatic molding machine with upper and lower sand shooting, the molding sand is evenly distributed after sand shooting, but due to the inconsistent compaction ratio at the upper and lower positions of the high mold, the resulting compactness is also inconsistent;

4. The design of the sand shooting channel of the sand cylinder is unreasonable (it needs to be adjusted when meeting special products). Even if it is an automatic molding machine for sand shooting up and down, for high molds, high sand molds are required, and the amount of sand shooting required is larger. If the sand shooting channel is designed If it is unreasonable, it will easily affect the kinetic energy of sand shooting, affect the filling of molding sand, and cause uneven compaction.

For example: A customer found that the compactness of the sand mold was not high during production. After analysis, it was found that the problem mainly lies in the quality of the sand. At the customer site, the engineer found that the sand treated by the sand was seriously granulated, with many mud lumps and large particles, and the surface of the casting was rough with sand sticking.

Problem analysis:

This result is due to the poor dust removal effect of sand treatment. While the molding sand is mixed with a large amount of resin sand cores, a little new sand is not added to supplement the daily molding and molding sand supply work, resulting in high mud content in the molding sand (by testing the mud content greater than 30%), the moisture distribution is uneven, and the fluidity becomes poor. The deteriorated molding sand is unevenly distributed after being shot by the molding machine, the granulated molding sand is locally aggregated, the surface of the cavity is rough, and the air permeability of the sand mold becomes poor.

Matters needing attention and improvement measures:

1. Strictly control the water content of the molding sand at 3%-4% (for Delin brand automatic molding machines) and the mud content to ensure good fluidity of the molding sand;

2. Increase the exhaust at the corner of the mold to make the sand mold easier to fill;

3. Design sand digging contacts or pressurized contacts (this is an auxiliary customization function for Delin brand automatic molding machines);

4. For high molds, it is recommended that customers open concave-convex molds, and design follow-up pressure plates on the upper compaction plate for mold needs.