Forging process introduction
2024-06-16 12:05:44
Forging is a processing method in which a forging press is used to apply pressure to a metal blank to cause plastic deformation to obtain a forged piece having a certain mechanical property, a certain shape and a size. Forging and stamping are of the same plastic processing properties, collectively referred to as forging.
Forging is a forming method commonly used in mechanical manufacturing. The forging can eliminate the as-cast looseness and weld holes of the metal, and the mechanical properties of the forging are generally superior to those of the same material. For important parts with high load and severe working conditions in machinery, forgings are often used except for rolled sheets, profiles or welded parts that are simple in shape.
Forging according to the temperature of the blank during processing can be divided into cold forging and hot forging. Cold forging is generally processed at room temperature, and hot forging is processed at a higher recrystallization temperature than the billet metal. Forging, which is sometimes heated, but the temperature does not exceed the recrystallization temperature, is called warm forging. However, this division is not completely uniform in production.
The recrystallization temperature of steel is about 460 ° C, but 800 ° C is generally used as the dividing line, and higher than 800 ° C is hot forging; between 300 and 800 ° C is called warm forging or semi-hot forging.
Forging can be divided into free forging, die forging, cold heading, radial forging, extrusion, forming and rolling, roll forging, and ramming according to the forming method. The deformation of the blank under pressure is basically free from external restrictions. It is also called open forging. The deformation of the billet of other forging methods is limited by the mold, which is called closed mode forging. The forming tool such as forming rolling, roll forging, boring and the like have a relative rotational motion with the blank, and the blank is subjected to point-by-point and asymptotic pressurization and forming, which is also called rotary forging.
Forging materials are mainly carbon steel and alloy steel of various compositions, followed by aluminum, magnesium, copper, titanium and the like and alloys thereof. The raw state of the material is bar, ingot, metal powder and liquid metal.
Generally, small and medium-sized forgings use round or square bars as blanks. The grain structure and mechanical properties of the bar are uniform and good, the shape and size are accurate, and the surface quality is good, which is convenient for mass production. As long as the heating temperature and deformation conditions are properly controlled, high-quality forgings can be forged without requiring large forging deformation.
Ingots are only used for large forgings. The ingot is an as-cast structure with large columnar crystals and a loose center. Therefore, it is necessary to break the columnar crystal into fine crystal grains by large plastic deformation, and loosely compact, in order to obtain excellent metal structure and mechanical properties.
The powder metallurgy preform which is pressed and sintered can be made into a powder forging by hot forging without flashing. Forging powder is close to the density of general die forgings, has good mechanical properties, and has high precision, which can reduce subsequent cutting. The powder forgings have a uniform internal structure and are not segregated and can be used to manufacture workpieces such as small gears. However, the price of powder is much higher than the price of ordinary bars, and its application in production is limited.
By applying static pressure to the liquid metal poured in the mold to solidify, crystallize, flow, plastically deform and form under pressure, a die forging of desired shape and properties can be obtained. Liquid metal die forging is a forming method between die casting and die forging, and is particularly suitable for complex thin-walled parts which are difficult to form by general die forging.
Different forging methods have different processes, among which the hot forging process has the longest process, the general order is: forging blanking; forging billet heating; roll forging blank; die forging; trimming; intermediate inspection, inspection forgings Dimensions and surface defects; heat treatment of forgings to eliminate forging stress and improve metal cutting performance; cleaning, mainly to remove surface oxide scale; correction; inspection, general forgings undergo appearance and hardness inspection, important forgings also undergo chemical composition analysis , mechanical properties, residual stress and other tests and non-destructive testing.
Forging is a combination of forging and stamping, and is a forming method for forming a part of a desired shape and size by using a hammer head, an anvil, a punch or a punching force of a forging machine to apply pressure to a blank to cause plastic deformation. .
In the forging process, the billet as a whole undergoes significant plastic deformation and a large amount of plastic flow; in the stamping process, the billet is mainly formed by changing the spatial position of each part of the area, and there is no plastic flow of a large distance inside. Forging is mainly used for processing metal parts, and can also be used to process certain non-metals, such as engineering plastics, rubber, ceramic blanks, brick blanks and composite materials.
Forging and metallurgy in the rolling, drawing, etc. are all plastic processing, or pressure processing, but forging is mainly used to produce metal parts, while rolling, drawing, etc. are mainly used to produce sheets, strips, pipes, General purpose metal materials such as profiles and wires.
At the end of the Neolithic Age, humans began to hammer natural copper to make decorations and small items. China has applied cold forging process manufacturing tools in about 2,000 BC. For example, the red copper objects unearthed from the Qijia Cultural Relics Site of Wuwei Huangniangtai in Gansu Province have obvious hammering marks. In the middle of the Shang Dynasty, weapons were made from ferroniobium, and a heating forging process was adopted. The block of wrought iron that appeared in the late spring and autumn is repeatedly heated and forged to extrude oxide inclusions and formed.
Initially, people used to forge with a tamper, and later forged the billet by pulling the rope and the pulley to lift the weight and then free fall. After the 14th century, animal power and hydraulic drop hammer forging occurred.
In 1842, the British inner Smith made the first steam hammer, making forging into the era of applied power. Forging hydraulic presses, motor-driven plywood hammers, air forging hammers and mechanical presses have emerged in the future. The plywood hammer was first used in the US Civil War (1861–1865) to mold forged parts, followed by steam forging hammers in Europe, and the die forging process was gradually promoted. By the end of the 19th century, the basic categories of modern forging machinery had been formed.
In the early 20th century, with the mass production of automobiles, hot die forging developed rapidly and became the main process of forging. In the mid-20th century, hot forging presses, flat forging machines and anvil-free forging hammers gradually replaced ordinary forging hammers, increasing productivity and reducing vibration and noise. With the development of new forging processes such as forging blanks, high-precision and high-life molds, hot extrusion, forming and rolling, as well as forging manipulators, robots and automatic forging lines, the efficiency and economic effects of forging production are constantly improving. .
The appearance of cold forging precedes hot forging. Early red, gold, silver flakes and coins were cold forged. The application of cold forging in mechanical manufacturing was promoted in the 20th century. Cold heading, cold extrusion, radial forging, swinging and rolling were successively developed, and an efficient forging process capable of producing precision parts without cutting was gradually formed.
Early stamping uses only simple tools such as shovel, shears, punches, hammers, and anvils to form metal sheets (mainly copper or copper alloy sheets, etc.) by hand cutting, punching, shoveling, and tapping. Manufacture of musical instruments and cans such as enamel, enamel and enamel. With the increase in the production of medium and thick plates and the development of stamping hydraulic presses and mechanical presses, stamping processing began to be mechanized in the mid-19th century.
In 1905, the United States began to produce coiled hot-rolled narrow strip steel. In 1926, it began to produce wide-band steel, and later cold-rolled strips appeared. At the same time, the output of plates and strips increased, the quality improved, and the cost decreased. Combined with the development of production of ships, railway vehicles, boilers, containers, automobiles, cans, etc., stamping has become one of the most widely used forming processes.
Forging is mainly classified according to the forming method and the deformation temperature. Forging according to forming method can be divided into two categories: forging and stamping; forging temperature can be divided into hot forging, cold forging, warm forging and isothermal forging.
Hot forging is a forging performed above the metal recrystallization temperature. Increasing the temperature can improve the plasticity of the metal, which is beneficial to improve the intrinsic quality of the workpiece and make it less prone to cracking. The high temperature also reduces the deformation resistance of the metal and reduces the tonnage of the required forging machinery. However, there are many hot forging processes, the workpiece precision is poor, the surface is not smooth, and the forgings are prone to oxidation, decarburization and burning.
Cold forging is forging at a temperature lower than the recrystallization temperature of the metal. The so-called cold forging pressure refers to the forging at normal temperature, and the forging at a temperature higher than normal temperature but not exceeding the recrystallization temperature is called temperature. Forging. The temperature of the forging pressure is higher, the surface is smoother and the deformation resistance is not large.
The workpiece formed by cold forging at normal temperature has high shape and dimensional precision, smooth surface, less processing steps, and is convenient for automated production. Many cold forged and cold stamped parts can be used directly as parts or articles without the need for cutting. However, in cold forging, due to the low plasticity of the metal, cracking is likely to occur during deformation, and the deformation resistance is large, and a large tonnage forging machine is required.
Isothermal forging is the constant temperature of the billet throughout the forming process. Isothermal forging is to take advantage of the high plasticity of certain metals at equal temperatures or to achieve specific microstructure and properties. Isothermal forging requires constant maintenance of the mold and billet at a constant temperature, and is only used for special forging processes such as superplastic forming.
Forging can change the metal structure and improve metal properties. After the ingot is hot forged, the original cast loose, pores, microcracks, etc. are compacted or welded; the original dendrites are broken to make the grains fine; at the same time, the original carbide segregation and unevenness are changed. Distribution, so that the organization is even, so that the internal compact, uniform, fine, comprehensive performance, reliable use of forgings. After the forging is deformed by hot forging, the metal is a fibrous structure; after cold forging deformation, the metal crystal is ordered.
Forging is a process in which a metal is plastically flowed to form a desired shape. The metal does not change in volume after plastic flow by external force, and the metal always flows to the portion with the least resistance. In production, the shape of the workpiece is often controlled according to these laws, and deformations such as upsetting, reaming, bending, and drawing are realized.
The forged workpieces are accurate in size and are advantageous for mass production. The dimensions of die forming, such as die forging, extrusion, and stamping, are accurate and stable. High-efficiency forging machines and automatic forging lines can be used to organize specialized large-volume or mass production.
The forging production process includes forging blanking before forming, forging billet heating and pretreatment; heat treatment, cleaning, calibration and inspection of the workpiece after forming. Commonly used forging machines are forging hammers, hydraulic presses and mechanical presses. The hammer has a large impact speed, which is good for metal plastic flow, but it will produce vibration. The hydraulic machine is forged by static force, which is good for forging metal and improving the structure. It works smoothly, but the productivity is low. The mechanical press has a fixed stroke and is easy to mechanize. And automation.
Future forging process will improve the intrinsic quality of forgings, develop precision forging and precision stamping technology, develop forging equipment and forging production lines with higher productivity and automation, develop flexible forging forming systems, develop new forging materials and forging processing methods. development of.
Improve the intrinsic quality of forgings, mainly to improve their mechanical properties (strength, plasticity, toughness, fatigue strength) and reliability. This requires a better application of the metal plastic deformation theory; the application of better intrinsic quality materials; correct pre-forging heating and forging heat treatment; more stringent and more extensive non-destructive testing of forgings.
Less and no cutting is the most important measure and direction for the machinery industry to improve material utilization, increase labor productivity and reduce energy consumption. The development of less forging blanks, no oxidation heating, and high hardness, wear resistance, long life mold materials and surface treatment methods will be beneficial to the expansion of precision forging and precision stamping applications.
Forging is a forming method commonly used in mechanical manufacturing. The forging can eliminate the as-cast looseness and weld holes of the metal, and the mechanical properties of the forging are generally superior to those of the same material. For important parts with high load and severe working conditions in machinery, forgings are often used except for rolled sheets, profiles or welded parts that are simple in shape.
Forging according to the temperature of the blank during processing can be divided into cold forging and hot forging. Cold forging is generally processed at room temperature, and hot forging is processed at a higher recrystallization temperature than the billet metal. Forging, which is sometimes heated, but the temperature does not exceed the recrystallization temperature, is called warm forging. However, this division is not completely uniform in production.
The recrystallization temperature of steel is about 460 ° C, but 800 ° C is generally used as the dividing line, and higher than 800 ° C is hot forging; between 300 and 800 ° C is called warm forging or semi-hot forging.
Forging can be divided into free forging, die forging, cold heading, radial forging, extrusion, forming and rolling, roll forging, and ramming according to the forming method. The deformation of the blank under pressure is basically free from external restrictions. It is also called open forging. The deformation of the billet of other forging methods is limited by the mold, which is called closed mode forging. The forming tool such as forming rolling, roll forging, boring and the like have a relative rotational motion with the blank, and the blank is subjected to point-by-point and asymptotic pressurization and forming, which is also called rotary forging.
Forging materials are mainly carbon steel and alloy steel of various compositions, followed by aluminum, magnesium, copper, titanium and the like and alloys thereof. The raw state of the material is bar, ingot, metal powder and liquid metal.
Generally, small and medium-sized forgings use round or square bars as blanks. The grain structure and mechanical properties of the bar are uniform and good, the shape and size are accurate, and the surface quality is good, which is convenient for mass production. As long as the heating temperature and deformation conditions are properly controlled, high-quality forgings can be forged without requiring large forging deformation.
Ingots are only used for large forgings. The ingot is an as-cast structure with large columnar crystals and a loose center. Therefore, it is necessary to break the columnar crystal into fine crystal grains by large plastic deformation, and loosely compact, in order to obtain excellent metal structure and mechanical properties.
The powder metallurgy preform which is pressed and sintered can be made into a powder forging by hot forging without flashing. Forging powder is close to the density of general die forgings, has good mechanical properties, and has high precision, which can reduce subsequent cutting. The powder forgings have a uniform internal structure and are not segregated and can be used to manufacture workpieces such as small gears. However, the price of powder is much higher than the price of ordinary bars, and its application in production is limited.
By applying static pressure to the liquid metal poured in the mold to solidify, crystallize, flow, plastically deform and form under pressure, a die forging of desired shape and properties can be obtained. Liquid metal die forging is a forming method between die casting and die forging, and is particularly suitable for complex thin-walled parts which are difficult to form by general die forging.
Different forging methods have different processes, among which the hot forging process has the longest process, the general order is: forging blanking; forging billet heating; roll forging blank; die forging; trimming; intermediate inspection, inspection forgings Dimensions and surface defects; heat treatment of forgings to eliminate forging stress and improve metal cutting performance; cleaning, mainly to remove surface oxide scale; correction; inspection, general forgings undergo appearance and hardness inspection, important forgings also undergo chemical composition analysis , mechanical properties, residual stress and other tests and non-destructive testing.
Forging is a combination of forging and stamping, and is a forming method for forming a part of a desired shape and size by using a hammer head, an anvil, a punch or a punching force of a forging machine to apply pressure to a blank to cause plastic deformation. .
In the forging process, the billet as a whole undergoes significant plastic deformation and a large amount of plastic flow; in the stamping process, the billet is mainly formed by changing the spatial position of each part of the area, and there is no plastic flow of a large distance inside. Forging is mainly used for processing metal parts, and can also be used to process certain non-metals, such as engineering plastics, rubber, ceramic blanks, brick blanks and composite materials.
Forging and metallurgy in the rolling, drawing, etc. are all plastic processing, or pressure processing, but forging is mainly used to produce metal parts, while rolling, drawing, etc. are mainly used to produce sheets, strips, pipes, General purpose metal materials such as profiles and wires.
At the end of the Neolithic Age, humans began to hammer natural copper to make decorations and small items. China has applied cold forging process manufacturing tools in about 2,000 BC. For example, the red copper objects unearthed from the Qijia Cultural Relics Site of Wuwei Huangniangtai in Gansu Province have obvious hammering marks. In the middle of the Shang Dynasty, weapons were made from ferroniobium, and a heating forging process was adopted. The block of wrought iron that appeared in the late spring and autumn is repeatedly heated and forged to extrude oxide inclusions and formed.
Initially, people used to forge with a tamper, and later forged the billet by pulling the rope and the pulley to lift the weight and then free fall. After the 14th century, animal power and hydraulic drop hammer forging occurred.
In 1842, the British inner Smith made the first steam hammer, making forging into the era of applied power. Forging hydraulic presses, motor-driven plywood hammers, air forging hammers and mechanical presses have emerged in the future. The plywood hammer was first used in the US Civil War (1861–1865) to mold forged parts, followed by steam forging hammers in Europe, and the die forging process was gradually promoted. By the end of the 19th century, the basic categories of modern forging machinery had been formed.
In the early 20th century, with the mass production of automobiles, hot die forging developed rapidly and became the main process of forging. In the mid-20th century, hot forging presses, flat forging machines and anvil-free forging hammers gradually replaced ordinary forging hammers, increasing productivity and reducing vibration and noise. With the development of new forging processes such as forging blanks, high-precision and high-life molds, hot extrusion, forming and rolling, as well as forging manipulators, robots and automatic forging lines, the efficiency and economic effects of forging production are constantly improving. .
The appearance of cold forging precedes hot forging. Early red, gold, silver flakes and coins were cold forged. The application of cold forging in mechanical manufacturing was promoted in the 20th century. Cold heading, cold extrusion, radial forging, swinging and rolling were successively developed, and an efficient forging process capable of producing precision parts without cutting was gradually formed.
Early stamping uses only simple tools such as shovel, shears, punches, hammers, and anvils to form metal sheets (mainly copper or copper alloy sheets, etc.) by hand cutting, punching, shoveling, and tapping. Manufacture of musical instruments and cans such as enamel, enamel and enamel. With the increase in the production of medium and thick plates and the development of stamping hydraulic presses and mechanical presses, stamping processing began to be mechanized in the mid-19th century.
In 1905, the United States began to produce coiled hot-rolled narrow strip steel. In 1926, it began to produce wide-band steel, and later cold-rolled strips appeared. At the same time, the output of plates and strips increased, the quality improved, and the cost decreased. Combined with the development of production of ships, railway vehicles, boilers, containers, automobiles, cans, etc., stamping has become one of the most widely used forming processes.
Forging is mainly classified according to the forming method and the deformation temperature. Forging according to forming method can be divided into two categories: forging and stamping; forging temperature can be divided into hot forging, cold forging, warm forging and isothermal forging.
Hot forging is a forging performed above the metal recrystallization temperature. Increasing the temperature can improve the plasticity of the metal, which is beneficial to improve the intrinsic quality of the workpiece and make it less prone to cracking. The high temperature also reduces the deformation resistance of the metal and reduces the tonnage of the required forging machinery. However, there are many hot forging processes, the workpiece precision is poor, the surface is not smooth, and the forgings are prone to oxidation, decarburization and burning.
Cold forging is forging at a temperature lower than the recrystallization temperature of the metal. The so-called cold forging pressure refers to the forging at normal temperature, and the forging at a temperature higher than normal temperature but not exceeding the recrystallization temperature is called temperature. Forging. The temperature of the forging pressure is higher, the surface is smoother and the deformation resistance is not large.
The workpiece formed by cold forging at normal temperature has high shape and dimensional precision, smooth surface, less processing steps, and is convenient for automated production. Many cold forged and cold stamped parts can be used directly as parts or articles without the need for cutting. However, in cold forging, due to the low plasticity of the metal, cracking is likely to occur during deformation, and the deformation resistance is large, and a large tonnage forging machine is required.
Isothermal forging is the constant temperature of the billet throughout the forming process. Isothermal forging is to take advantage of the high plasticity of certain metals at equal temperatures or to achieve specific microstructure and properties. Isothermal forging requires constant maintenance of the mold and billet at a constant temperature, and is only used for special forging processes such as superplastic forming.
Forging can change the metal structure and improve metal properties. After the ingot is hot forged, the original cast loose, pores, microcracks, etc. are compacted or welded; the original dendrites are broken to make the grains fine; at the same time, the original carbide segregation and unevenness are changed. Distribution, so that the organization is even, so that the internal compact, uniform, fine, comprehensive performance, reliable use of forgings. After the forging is deformed by hot forging, the metal is a fibrous structure; after cold forging deformation, the metal crystal is ordered.
Forging is a process in which a metal is plastically flowed to form a desired shape. The metal does not change in volume after plastic flow by external force, and the metal always flows to the portion with the least resistance. In production, the shape of the workpiece is often controlled according to these laws, and deformations such as upsetting, reaming, bending, and drawing are realized.
The forged workpieces are accurate in size and are advantageous for mass production. The dimensions of die forming, such as die forging, extrusion, and stamping, are accurate and stable. High-efficiency forging machines and automatic forging lines can be used to organize specialized large-volume or mass production.
The forging production process includes forging blanking before forming, forging billet heating and pretreatment; heat treatment, cleaning, calibration and inspection of the workpiece after forming. Commonly used forging machines are forging hammers, hydraulic presses and mechanical presses. The hammer has a large impact speed, which is good for metal plastic flow, but it will produce vibration. The hydraulic machine is forged by static force, which is good for forging metal and improving the structure. It works smoothly, but the productivity is low. The mechanical press has a fixed stroke and is easy to mechanize. And automation.
Future forging process will improve the intrinsic quality of forgings, develop precision forging and precision stamping technology, develop forging equipment and forging production lines with higher productivity and automation, develop flexible forging forming systems, develop new forging materials and forging processing methods. development of.
Improve the intrinsic quality of forgings, mainly to improve their mechanical properties (strength, plasticity, toughness, fatigue strength) and reliability. This requires a better application of the metal plastic deformation theory; the application of better intrinsic quality materials; correct pre-forging heating and forging heat treatment; more stringent and more extensive non-destructive testing of forgings.
Less and no cutting is the most important measure and direction for the machinery industry to improve material utilization, increase labor productivity and reduce energy consumption. The development of less forging blanks, no oxidation heating, and high hardness, wear resistance, long life mold materials and surface treatment methods will be beneficial to the expansion of precision forging and precision stamping applications.
Curtain Wall Glass,Colored Glass,Glass Wall,Glass Curtain Wall
SHANDONG TOP LEADER GLASS CO.,LTD , https://www.topleaderglass.com