What are the differences between standard forged valves and cast valves?

What are the differences between standard forged valves and cast valves?

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What are the differences 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 are also high pressure, can be 1500Lb, 2500Lb), caliber most are more than DN50. Forged valve is forged out, generally used in high grade pipeline, caliber is relatively small, generally below DN50.
Casting valve is cast into the valve, the general casting valve pressure grade is relatively low (such as PN16, PN25, PN40, but there are also high pressure, can be 1500Lb, 2500Lb), caliber most are more than DN50. Forged valve is forged out, generally used in high grade pipeline, caliber is relatively small, generally below DN50.
A, casting
1, casting: is to melt the metal into a liquid that meets certain requirements and cast into the mold, after cooling and solidification, cleaning treatment to get a predetermined shape, size and performance of the casting (parts or blank) process. Basic technology of modern machinery manufacturing industry.
2, casting production of low cost, for complex shape, especially with complex cavity parts, more can show its economy; At the same time, it has wider adaptability and better comprehensive mechanical properties.
3, but casting production required materials (such as metal, wood, fuel, molding materials, etc.) and equipment (such as metallurgical furnace, sand mixing machine, molding machine, core making machine, sand falling machine, shot blasting machine, cast iron plate, etc.) more, and will produce dust, harmful gas and noise and pollution of the environment.
4. Casting is one of the earliest metal hot working processes mastered by human beings, with a history of about 6000 years. In 200 AD, copper frog castings appeared in Mesopotamia. Between the 13th CENTURY BC and the 1st century AD, China had entered the heyday of bronze casting, and the craft had reached a fairly high level. For example, the simuwu square ding weighing 875 kg in the Shang Dynasty, the Yi Zun plate of Marquis Zeng in the Warring States Period, and the diopter mirror of the Western Han Dynasty were all the most famous products of ancient casting. The early casting was greatly influenced by pottery, and most of the castings were tools or utensils in agricultural production, religion and life, with strong artistic colors. In 513 BC, China produced the world’s first recorded cast iron — the ding cast by the State of Jin (about 270 kg). Around the 8th century, Europe began to produce cast iron. After the industrial revolution of the 18th century, castings entered a new period of service for large industry. Into the 20th century, the rapid development of casting, has developed nodular cast iron, malleable cast iron, carbon stainless steel and aluminum copper, aluminum silicon, aluminum magnesium alloy, titanium base, nickel base alloy and other casting metal materials, and develop a new process for gray cast iron breeding treatment. After 50′s, there appeared wet sand high pressure modeling, chemical hardening sand modeling and core making, negative pressure modeling and other special casting, shot blasting cleaning and other new technologies.
5, there are many kinds of casting, according to the modeling method is customarily divided into: (1) ordinary sand casting, including wet sand, dry sand 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: (1) cast (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 type, half and last for a long time, the pros and cons of mold preparation is the main factors influencing the casting quality; (2) the melting and casting of casting metal, casting metal (casting alloy) are mainly cast iron, cast steel and cast non-ferrous alloy; Casting treatment and inspection, casting treatment including mold core and casting surface foreign bodies, removal of pouring riser, shovel grinding burr and seam and other protrusions and heat treatment, plastic, rust treatment and rough processing.
Second, the forging
1, forging: is the use of forging machinery to apply pressure on the metal billet, so that it produces plastic deformation to obtain a certain mechanical properties, a certain shape and size of forging processing method.
2. One of the two major components of forging. Through forging can eliminate the loose state of the metal, welding holes, the mechanical properties of the forgings are generally better than the same material castings. Forgings are mostly used for the important parts with high load and severe working conditions, except for the simple plate, profile or welding parts that can be rolled.
3, forging according to the forming method can be divided into: ① open forging (free forging). The use of impact force or pressure to make the metal in the upper and lower two iron (anvil block) deformation to obtain the required forgings, mainly manual forging and mechanical forging two. (2) Closed forging. The forging can be divided into die forging, cold heading, rotary forging, extrusion and so on. According to the deformation temperature forging can be divided into hot forging (processing temperature is higher than the recrystallization temperature of the billet metal), warm forging (lower than the recrystallization temperature) and cold forging (room temperature).
4, forging materials are mainly carbon steel and alloy steel of various components, followed by aluminum, magnesium, titanium, copper and their alloys. The original state of the material is bar, ingot, metal powder and liquid metal. The ratio of the cross section area of metal before deformation to the die section area after deformation is called forging ratio. Correct selection of forging ratio has a great bearing on improving product quality and reducing cost.
Identification of castings and forgings
1, the surface structure of the fine density of the forging, the surface of the casting should be thicker, and the machining surface of the forging should be brighter.
2, cast iron section gray color, and forged steel section silver bright.
3. Listen to the sound, the forging is dense, the sound is clear after the blow, and the sound of the casting is dull.
4, with grinder grinding to see the two sparks with different (forgings bright) and so on.