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The difference between forged and cast valves

Casting valve is cast into the valve, the general casting valve pressure grade is relatively low (such as PN16, PN25, PN40, but there is also high pressure, can be to 1500LD, 2500LB), most of the caliber is more than DN50. Forging valves are forged out. They are generally used in high grade pipelines. The caliber is small, and they are generally below DN50.
A, casting
1. Casting: it is the process of melting metal into a liquid that meets certain requirements and pouring it into the casting mold. After cooling and solidification, the casting (parts or blank) is obtained with predetermined shape, size and performance. The basic technology of modern machinery manufacturing industry.
2, casting production of blank cost is low, for complex shape, especially with complex cavity parts, more can show its economy; At the same time, it has wide adaptability and good comprehensive mechanical properties.
3, but the materials needed for casting production (such as metal, wood, fuel, molding materials, etc.) and equipment (such as metallurgical furnace, sand mixing machine, molding machine, core-making machine, shaker, shot blasting machine, cast iron plate, etc.) are more, and will produce dust, harmful gas and noise and pollute the environment.
4. Casting is a kind of metal hot working technology that has a history of about 6000 years. In 3200 BC, castings of bronze frogs appeared in Mesopotamia. Between 13 BC and 10 BC century, China has entered the heyday of bronze castings, the process has reached a fairly high level, such as the Shang Dynasty Simuwu square Ding weighing 875 kg, the Warring States Dynasty Jinghou Yi Zunpan and the Western Han Dynasty transparent mirror are the representative products of ancient casting. Early casting was greatly influenced by pottery, and most of the castings were tools or utensils for agricultural production, religion, life and other aspects, with strong artistic color. In 513 BC, China produced the first cast iron in written records in the world – the Jin Casting Ding (about 270 kg). Around the 8th century, Europe began to produce cast iron. After the industrial revolution in the 18th century, castings entered a new period of serving large industries. In the 20th century, the rapid development of casting, has developed the ductile iron, malleable cast iron, ultra-low carbon stainless steel and aluminum copper, aluminum silicon, aluminum magnesium alloy, titanium base, nickel base alloy and other casting metal materials, and invented a new process for gray cast iron to carry out the treatment. After the 1950s, new technologies such as wet sand high pressure molding, chemical hardening sand molding, core making, negative pressure molding, and other special casting and shot blasting were introduced.
5. There are many kinds of casting. According to the modeling method, it is customarily divided into 0 ordinary sand casting, including wet sand type, dry sand type and chemical hardening sand type 3. (2) special casting, press molding materials and can be divided into natural mineral sand as the main special casting molding materials (e.g., investment casting, mold casting, shell mold casting foundry, negative pressure casting, mold casting, ceramic mold casting, etc.) and metal as the main mold material of special casting (such as metal mold casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.).
6, casting process usually includes: (casting (containers) makes liquid metal solid casting, casting according to the materials can be divided into sand mold, metal, ceramic, mud, graphite, etc., can be divided by use disposable, semi permanent and permanent type, mold preparation quality are the main factors influencing the casting quality; The melting and pouring of casting metal, casting metal (casting alloy) mainly includes cast iron, cast steel and cast non-ferrous alloy; (3) casting treatment and inspection, casting treatment, including the removal of core and casting surface foreign bodies, casting riser removal, shovel grinding burr and other protrusion, heat treatment, shaping, antirust treatment and rough machining. Inlet pump valve
The second forging
1, forging: is the use of forging machinery on the metal billet pressure, plastic deformation to obtain a certain mechanical properties, a certain shape and size of forgings processing method.
2, one of the two main components of forging. Through forging can eliminate the metal as cast loose, welding holes, the mechanical properties of forgings is generally better than the same material castings. For the important parts with high load and severe working conditions in machinery, forgings are mostly used in addition to the plate, profile or welding parts with simple shape that can be rolled.
3, forging according to the forming method can be divided into: 0 open forging (free forging). The use of force or pressure to make the metal between the upper and lower two anti-iron (anvil block) deformation to obtain the required forgings, mainly manual forging and mechanical forging. ② Closed mode forging. The metal blank is deformed under pressure in the forging die chamber of a certain shape, and the forging can be divided into die forging, cold forging, rotary forging, extrusion and so on. According to the deformation temperature forging can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (normal temperature).
4, the forging material is mainly a variety of components of carbon steel and alloy steel, followed by aluminum, magnesium, titanium, copper and its alloy. The original state of the material includes rods, casting chains, metal powders and liquid metals. The ratio of the cross sectional area of the metal before deformation to the die sectional area after deformation is called the forging ratio. Correct choice of forging than to improve product quality, reduce the cost has a great relationship.

Post time: Jun-01-2021