Casting valve is cast into the valve, the general casting pressure of the valve are relatively low (such as PN16, PN25, PN40, but there are high-pressure, can be 1500Lb ,, 2500Lb), most of the caliber of more than DN50. Forged
Valves are forged out, are generally used in the high level of the pipeline, the caliber is relatively small, are generally below DN50. First, the casting valve 1, casting: that is, the metal smelting meet certain requirements of the liquid and poured into the mold, the cooling and solidification, cleaning process to get a predetermined shape, size and performance of the casting (parts or rough) process process. The basic technology of modern machinery manufacturing industry. 2, casting the rough production of low cost, complex shape, especially with complex cavity parts, more shows its economy; its wide adaptability and has good mechanical properties. 3, but the casting of materials needed for production (such as metal, wood, fuel, modeling materials, etc.) and equipment (such as metallurgical furnace, sand mixer, molding machine, core machine, sand machine, shot blasting machine, ) More, and will produce dust, harmful gases and noise pollution of the environment. 4, foundry is a metal mastery earlier metal thermal processing technology, about 6,000 years of history. In 3200 BC, copper frog castings appeared in Mesopotamia. Between 13 BC and the 10th century BC, China had entered the heyday of bronze castings and reached a fairly high level of craftsmanship. For example, the Shang dynasty sold 875 kilograms of distillers' The translucent mirror are all representatives of the ancient casting products. Early casting affected by the larger pottery, casting most of the agricultural production, religion, life and other tools or appliances, artistic color thicker. In 513 BC, China casts out the earliest recorded iron castings in the world - Jinzuo Dingding (about 270kg in weight). Before and after the eighth century AD, Europe began to produce cast iron pieces. After the industrial revolution of the eighteenth century, castings entered a new era of service to large industries. Into the 20th century, casting rapid development, has developed a ductile iron, malleable iron, ultra-low carbon stainless steel and aluminum copper, aluminum silicon, aluminum-magnesium alloy, titanium-based, nickel-based alloy casting metal materials, and invented the gray Cast iron for breeding process of new technology. After the 1950s, wet sand high pressure modeling, chemical hardening sand modeling and core making, negative pressure modeling and other special casting, shot blasting and other new technologies emerged. 5, casting a lot of types, according to modeling methods used to be divided into: ① ordinary
Sand Casting, including wet sand type, dry sand type and chemical hardening sand type 3 categories. ② special casting, according to the molding material can be divided into natural sand as the main molding material for the special casting (such as
Investment Casting, mud casting, casting workshop shell casting, negative pressure casting, real casting, ceramic casting Etc.), and special casting (such as metal casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.) mainly made of metal as a mold material. 6, the casting process usually include: ① mold (liquid metal into a solid state casting container) preparation, the mold can be divided according to the materials used can be divided into sand, metal, ceramic, mud type, graphite type, according to the frequency of use can be divided For the one-time, semi-permanent and permanent type, the advantages and disadvantages of the mold preparation are the main factors that affect the quality of the castings. ② The melting and pouring of foundry metals are mainly made of cast iron, cast steel and cast nonferrous alloys; ③ casting processing and testing, casting processing, including removal of the surface of the core and casting foreign body, cut off the riser, shovel burrs and ptosis and other protrusions and heat treatment, plastic surgery, anti-rust treatment and roughing. Imported pump valve Second, the forging valve 1, Forging: Forging is the use of forging machinery to exert pressure on the metal billet, so that it has a plastic deformation to obtain a certain mechanical properties, a certain shape and size forging processing methods. 2, forging one of the two major components. By forging can eliminate the loose cast metal, welding holes, mechanical properties of forgings generally better than the same material castings. Mechanical load, the working conditions of critical parts, in addition to the shape of the more available rolled plate, profile or welded parts, the use of more forgings. 3, forging by forming method can be divided into: ① open forging (free forging). The use of impact or pressure so that the metal in the upper and lower two against the iron (anvil) between the deformation to obtain the required forgings, mainly hand forging and mechanical forging two. ② closed mode forging. Metal billet in forging die with a certain shape forging deformation obtained forgings, can be divided into forging, cold heading, rotary forging, extrusion and so on. Forging by deformation temperature can be divided into hot forging (processing temperature is higher than the recrystallization temperature of billets metal), warm forging (below the recrystallization temperature) and cold forging (room temperature). 4, forging materials are mainly composed of various components of carbon steel and alloy steel, followed by aluminum, magnesium, titanium, copper and its alloys. The original state of the material bar, ingot, metal powder and liquid metal. Metal in the deformation of the cross-sectional area and deformation after the broken area ratio called forging ratio. Correct choice of forging ratio to improve product quality, reduce costs have a lot to do.
