1. Casting: 1. Casting: It is the process of sme […]
1. Casting: It is the process of smelting metal into a liquid that meets certain requirements and pouring it into a mold. After cooling, solidification and cleaning, a casting (part or blank) with a predetermined shape, size and performance is obtained. The basic technology of modern machinery manufacturing industry.
2. The cost of the blank produced by casting is low, and it can show its economical efficiency for parts with complex shapes, especially with complicated inner cavities; at the same time, it has wide adaptability and good comprehensive mechanical properties.
3. But the materials (such as metal, wood, fuel, modeling materials, etc.) and equipment (such as metallurgical furnaces, sand mixers, molding machines, core making machines, shakeout machines, shot blasting machines, cast iron plates, etc.) required for casting production ) Is more, and will produce dust, harmful gas and noise and pollute the environment.
4. Casting is a kind of metal thermal processing technology that humans have mastered earlier, with a history of about 6000 years. In 3200 BC, copper frog castings appeared in Mesopotamia. Between the 13th and 10th centuries BC, China has entered the heyday of bronze castings, and the craftsmanship has reached a very high level, such as the 875 kg Simuwu Fang Ding of the Shang Dynasty, the Zenghou Yizun plate of the Warring States Period and the Western Han Dynasty Translucent mirrors are all representative products of ancient casting. Early casting was greatly influenced by pottery. Most of the castings were tools or utensils used in agricultural production, religion, and life, with a strong artistic color. In 513 BC, China cast iron castings (about 270 kilograms in weight), a cast iron piece that was seen in the world as early as written records. Around the 8th century, Europe began to produce iron castings. After the Industrial Revolution in the 18th century, castings entered a new period of service to large industries. In the 20th century, the rapid development of casting has developed. Nodular cast iron, malleable cast iron, ultra-low carbon stainless steel, aluminum copper, aluminum silicon, aluminum magnesium alloy, titanium-based, nickel-based alloy and other casting metal materials have been developed. A new process for inoculation of cast iron. After the 1950s, new technologies such as green sand high-pressure modeling, chemical hardening sand modeling and core making, negative pressure modeling, and other special casting, shot blasting, etc. appeared.
5. There are many types of casting, according to the habit of modeling methods:
①Ordinary sand casting, including 3 types of green sand, dry sand and chemically hardened sand.
②Special casting, according to the modeling material, can be divided into special casting with natural mineral sand and gravel as the main modeling material (such as investment casting, clay casting, shell casting in the foundry, negative pressure casting, solid casting, ceramic casting) Etc.) and special casting with metal as the main mold material (such as metal mold casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.).
6. The casting process usually includes:
①Preparation of casting molds (containers that make liquid metal into solid castings). Casting molds can be divided into sand, metal, ceramic, clay, graphite, etc. according to the materials used, and can be divided into disposables and castings according to the number of uses. The quality of preparation is the main factor affecting the quality of castings;
②The melting and pouring of cast metal, cast metal (casting alloy) mainly includes cast iron, cast steel and cast non-ferrous alloy;
③ Casting processing and inspection. Casting processing includes removing foreign bodies on the core and surface of castings, removing pouring risers, shoveling burrs and draping seams and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining.