Views: 2 Author: Site Editor Publish Time: 2020-06-12 Origin: Site
1. Casting: the process of smelting metal into a liquid that meets certain requirements and pouring it into a mold. After cooling and solidification and cleaning, a casting (part or blank) with a predetermined shape, size and performance is obtained. The basic process of modern machinery manufacturing industry.
2. The cost of the blanks produced by casting is low. For the parts with complex shapes, especially with complex internal cavities, it can show its economy; at the same time, it has a wider adaptability and has better comprehensive mechanical properties.
3. However, the materials (such as metal, wood, fuel, molding materials, etc.) and equipment (such as metallurgical furnaces, sand mixers, molding machines, core making machines, sand falling machines, shot blasting machines, cast iron flat plates, etc.) required for casting production ) More, and will produce dust, harmful gases and noise and pollute the environment.
4. Casting is a kind of metal hot processing technology that has been mastered by humans for a long time, and has 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 its craftsmanship has reached a very high level. Light-transmitting mirrors are representative products of ancient casting. Early castings were greatly influenced by pottery. Most of the castings were tools or utensils for agricultural production, religion, life, etc., and the artistic color was relatively strong. In 513 BC, China cast the world's earliest cast iron parts, Jin Guo Zhu Ding (about 270 kg). Around the 8th century AD, Europe began to produce cast iron parts. After the industrial revolution in the 18th century, castings entered a new period of service for 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 alloys and other casting metal materials, and invented the gray A new process for inoculation of cast iron. After the 1950s, new processes such as wet sand high-pressure molding, chemically hardened sand molding and core-making, negative pressure molding, and other special castings and shot blasting cleaning have appeared.
5. There are many types of casting, which are customarily divided into: ① ordinary sand casting, including 3 types of wet sand, dry sand and chemically hardened sand. ②Special casting can be divided into special casting with natural mineral sandstone as the main modeling material (such as investment casting, mud casting, shell casting in casting workshop, negative pressure casting, solid casting, ceramic casting) Etc.) and special castings with metal as the main casting material (such as metal casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.). 6. The casting process usually includes: ①Preparation of the casting mold (making liquid metal into a container for solid castings). The casting mold can be divided into sand mold, metal mold, ceramic mold, clay mold, graphite mold, etc. according to the materials used, and can be divided according to the number of uses For one-time type, semi-permanent type and permanent type, the quality of casting preparation is the main factor affecting the quality of castings; ② melting and pouring of casting metals, casting metals (casting alloys) mainly include cast iron, cast steel and cast nonferrous alloys; ③Processing and inspection of castings. The processing of castings includes the removal of foreign objects on the core and casting surface, the removal of risers, burrs and burrs and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining.
1. Forging: It is a processing method that uses forging machinery to apply pressure to metal blanks to cause plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes.
2. One of the two major components of forging. The forging can eliminate the looseness of the cast metal of the metal, weld the holes, and the mechanical properties of the forging are generally better than the casting of the same material. For the important parts with high load and severe working conditions in the machinery, in addition to the simpler shapes of rolled plates, profiles or welded parts, forgings are mostly used.
3. Forging can be divided according to the forming method: ① open forging (free forging). The impact or pressure is used to deform the metal between the two upper and lower irons (anvils) to obtain the required forgings. There are mainly two types of manual forging and mechanical forging. ② Forging in closed mode. The metal blank is compressed and deformed in the forging die cavity with a certain shape to obtain forgings, which can be divided into die forging, cold heading, rotary forging, and extrusion. Forging according to deformation temperature can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the blank metal), warm forging (below the recrystallization temperature) and cold forging (normal temperature).
4. Forging materials are mainly carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, titanium, copper and their alloys. The original state of the material is bar stock, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the die-cut area after deformation is called the forging ratio. Choosing the correct forging ratio has a lot to do with improving product quality and reducing costs.