Sand casting is the most common method for copper gaskets used in sand casting production, which has the advantages of wide adaptability and relatively simple production preparation. However, the dimensional accuracy, surface quality, and internal quality of castings produced by this method are far from meeting the requirements of mechanical parts, and the production process is more complicated, and the realization of mechanized and automated production requires huge investment. In the production of some special parts and special technical requirements The technical and economic indicators are relatively low, so the application of sand casting in foundry production is limited to a certain extent. In addition to sand casting, special casting has formed a variety of other casting methods different from sand casting by changing the casting material, pouring method, the form of liquid alloy filling the casting mold, or the solidification conditions of the casting. Foundry workers refer to other casting methods that are different from the sand casting process as special casting. Common special casting methods in the machinery manufacturing industry are:
1. Investment casting. It is a method of casting no-cut or less-cut castings with higher dimensional accuracy and lower surface roughness values using fusible models and high-performance shells; metal mold casting. It is a method of using a metal mold to increase the cooling rate of the casting, to achieve one-type multi-casting, and to obtain a casting with a dense crystalline structure.
2. Pressure casting. It is a method of obtaining precision castings by changing the filling and crystallization and solidification conditions of liquid alloys, so that liquid alloys fill the molds under high pressure and high speed conditions, and form and crystallize under high pressures, thereby obtaining precision castings; lost foam casting. It is a foamed plastic model similar in size and shape to the casting, bonded and combined into a model family, brushed with a refractory coating and dried, buried in quartz sand for vibration modeling, and then poured with liquid metal under certain conditions to make the model The method of vaporizing and making the molten metal occupy the position of the model, and forming the desired casting after the molten metal solidifies and cools.
3. Low pressure casting. It is a casting method between gravity casting lead-free copper, which refers to the process of injecting molten metal into the mold under the action of the earth’s gravity, and pressure casting. By changing the filling and solidification conditions, the liquid alloy is filled steadily from bottom to top under the condition of low pressure and low speed, and crystallized and solidified sequentially from top to bottom under the action of low pressure, so as to obtain high-quality castings with dense structure.
Post time: Jun-15-2022