Casting is a forming method in which metal parts or blanks of a certain shape, size and performance are obtained after heating and melting, pouring them into a prefabricated casting mold, and after cooling and solidifying. Due to its large size, heavy weight and complex structure, the casting process of large steel castings requires special attention. The following will introduce the casting methods and precautions for large steel castings.
First, the casting method.
1.Sand casting.
Sand casting is a casting method in which the molding material is made into a pattern, the sand box is filled with sand, and the pattern is taken out. This method is most widely used in the production of large steel castings, as sand casting can accommodate a wide range of different shapes and sizes of castings at a lower cost. The disadvantage of sand casting is that the production cycle is long and requires a complex demoulding and trimming process.
2.Solid casting.
Solid casting is made of polyvinyl alcohol or foam plastic and other materials, the pattern is covered in the sand box by coating and binder, and after the paint is dried, the pattern is heated and melted to obtain the casting method of casting. The advantages of solid casting are that it can reduce the time of molding and demoulding, improve production efficiency, and at the same time have a smooth surface of the casting and high dimensional accuracy. However, solid casting requires the use of high-precision manufacturing equipment, and the cost is high.
3.Die casting.
Die casting is a casting method that uses high pressure to inject molten metal into the mold. When large steel castings are produced by die casting, a high-pressure die casting machine is required. The advantages of die casting are high production efficiency, smooth surface of castings, high dimensional accuracy, and the ability to reduce or eliminate defects such as porosity and slag inclusions. However, die casting requires the use of high-precision molds and equipment, and the cost is high.
2. Precautions.
1.Mold design.
The mold design of large steel castings needs to be reasonably designed according to the structure and size of the castings to ensure the strength, stiffness and stability of the mold. At the same time, the gating system and cooling system of the mold also need to be reasonably designed to ensure that the molten metal can be injected into the mold smoothly and be well cooled.
2.Metallic materials.
The material of large steel castings needs to be selected according to the requirements of their use. Generally speaking, large steel castings need to have good mechanical properties, wear resistance, corrosion resistance and toughness. At the same time, the chemical composition and impurity content of metal materials need to be controlled to ensure the quality and performance of castings.
3.Casting process.
The casting process for large steel castings needs to be selected according to the specific production conditions and casting requirements. In the casting process, it is necessary to control the process parameters such as temperature, pouring speed and pouring pressure of the molten metal to ensure the quality and performance of the casting. At the same time, it is also necessary to pay attention to prevent the occurrence of defects such as porosity, slag inclusion, and cracks.
4.Quality control.
Quality control of large steel castings is key to ensuring their performance and service life. In the production process, strict quality inspection and control are required, including material inspection, mold inspection, semi-finished product and finished product inspection, etc. At the same time, it is also necessary to establish a sound quality management system to ensure the stability and reliability of the production process.
In short, the casting of large steel castings is a highly technical work, which requires comprehensive consideration of casting methods, material selection, process development and quality control. In actual production, it needs to be handled flexibly according to the specific situation to achieve the best production results and quality assurance.