一. Casting:
1. Casting: It is the process of smelting metal into a liquid that meets certain requirements and pouring it into a casting 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 complex internal cavities; at the same time, it has a wide range of adaptability and better 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 mankind has 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. Translucent mirrors are all representative products of ancient casting. Early casting was greatly influenced by pottery, and 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 the world's first cast iron found in written records-the Jin Kingdom cast tripod (approximately 270 kg). 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 been 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, which are divided into: 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, casting workshop shell casting, 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). The casting molds can be divided into sand molds, metal molds, ceramic molds, clay molds, graphite molds, etc., according to the number of uses. For disposable, semi-permanent and permanent, the quality of the mold preparation is the main factor that affects the quality of castings; ②The melting and pouring of cast metals, cast metals (casting alloys) mainly include cast iron, cast steel and cast non-ferrous alloys; ③ Casting processing and inspection. Casting processing includes removing foreign matter on core and casting surface, removing pouring risers, shoveling burrs and draping seams and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining.
二. Forging:
1. Forging: It is a processing method that uses forging machinery to apply pressure to metal blanks to produce plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes.
2. One of the two major components of forging. Forging can eliminate the looseness of the metal as-cast and welded holes, and the mechanical properties of forgings are generally better than those of castings of the same material. For the important parts of machinery with high load and severe working conditions, forgings are mostly used except for simpler shapes that can be rolled, profiles or welded parts.
3. According to the forming method, forging can be divided into: ① open forging (free forging). Using impact or pressure to deform the metal between the upper and lower anvils (anvils) to obtain the required forgings, there are mainly manual forging and mechanical forging. ②Closed mode forging. The metal blank is compressed and deformed in a forging die with a certain shape to obtain forgings, which can be divided into die forging, cold heading, rotary forging, and extrusion. According to the deformation temperature, forging can be divided into hot forging (processing temperature higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (normal temperature).
5. Forging materials are mainly carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, titanium, copper, etc. and their alloys. The original state of the material includes bar stock, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the die cross-sectional area after deformation is called the forging ratio. The correct choice of forging ratio has a lot to do with improving product quality and reducing costs.
