Detailed explanation of gear forging annealing heat treatment process

Precision forged gear

Carburized steel 20CrMnTi forgings are air-cooled to room temperature after forging to obtain a mixed structure composed of ferrite, pearlite, Widmansite and bainite. After heating to 930°C for carburizing and cooling to 850°C for quenching, coarse austenites still appear. Body grains, showing obvious tissue heredity. If after forging, after heat treatment, a mixed structure of ferrite and pearlite is obtained, after carburizing and quenching, the structure is obviously refined, and there is no organization heredity, which is the significance of heat treatment after forging. The main purposes of heat treatment for small gear forgings are:

(1) Eliminate forging stress.

(2) Obtain a relatively uniform metallographic structure and improve cutting performance.

(3) Reduce the deformation of the gear after carburizing and quenching.

gear

1. Isothermal annealing

The forging material is 20CrMnTi, and the equipment is an isothermal annealing continuous furnace, which consists of a high temperature zone, a rapid cooling zone and an isothermal zone.
The isothermal annealing process is an advanced high-temperature heating zone for forgings. It is heated from room temperature to 940°C and held for a period of time to make it fully austenitized. Then it enters the rapid cooling zone and is rapidly cooled from 950°C to 650°C within 5~10 minutes. Make the forgings quickly enter the correct phase transformation range, and then keep warm at 650°C to make the forgings fully phase-transform to ferrite + pearlite structure, and send them out of the furnace to air cool to room temperature.

It should be noted that due to the different sizes of forgings, the isothermal annealing process curve should be adjusted according to the actual situation of the production site. The principle is to ensure that the metallographic structure of forgings is 1~3, and the surface hardness is preferably controlled at 160~210HBW. After testing, this production process is also suitable for the annealing of small shaft forgings, and the production capacity of the equipment is 600kg/h.

2. Waste heat annealing

The forging material is 20CrMnTi, and the equipment is a mesh belt waste heat annealing furnace, which is composed of a heating furnace and a rapid cooling chamber. The preheating annealing process is that after the forging is formed, it is directly sent into the heating furnace, kept at 650°C for 45 minutes, and then enters the rapid cooling room, and is cooled to below 70°C within 20 minutes.

When annealing with residual heat of forgings, the key point is to grasp the temperature of forgings entering the furnace and the holding time in the furnace. After field tests, it is found that the temperature of general forgings entering the furnace should be controlled above 800°C. At this time, the metallographic phase and hardness after annealing are most suitable; Forgings below 800℃ are likely to have unqualified microstructure and hardness after annealing with residual heat, so strict attention should be paid to them. The holding time and temperature cannot be generalized, and should be adjusted appropriately according to the size and thickness of the forging.

3. Comparison of isothermal annealing and waste heat annealing

gear

(1) Isothermal annealing process

Advantage:

a. The process stability is high, and the dispersion of forging hardness can be controlled within 20HBW/batch. The whole annealing process is easy to control, and the metallographic structure and surface hardness of the forgings after annealing can meet the requirements, and it is also the most widely used heat treatment method for forgings at present.

b. Because it is independent from the forging production line and does not interact with other forging equipment’s mobility, it will neither stop the furnace due to the failure of a certain equipment, nor stop the forging production line due to the abnormality of the isothermal annealing line.

Disadvantages:

a. After the forging is completely cooled, reheat it to about 940°C, which will cause energy waste.

b. The isothermal annealing line cannot be incorporated into the forging production line to realize the “one-flow” forging production mode.

Therefore, it is necessary to set up a special store for normalizing goods, and wait for the amount of forgings to meet the production capacity of the isothermal annealing equipment before they are put into the furnace. Such an intermediate goods store will occupy a large amount of site resources and current assets, which does not meet the “0” intermediate storage in the Toyota production method. thought of.

Precision forged gear

(2) Waste heat annealing process

Advantage:

a. Energy saving and environmental protection are in line with the low-carbon economy advocated by our country. It uses the waste heat of forgings, saves the heating process, and its energy consumption can be reduced to 50% of that of general isothermal annealing.

b. Combined with the forging production line, it saves the site resources and working capital occupied by the warehouse in the middle.

Disadvantage:

a. Although the residual heat annealing process has been proven to be reliable and has been widely used in production, due to the different forging equipment and the different operating speeds of forging operators, it is relatively difficult to control the furnace entering temperature, which is easy to cause tissue damage. Unqualified hardness.

b. It must follow each forging production line and interact with the mobility of other forging equipment, that is to say, any failure of the waste heat annealing furnace or any equipment of this forging production line will directly cause the entire production line to stop production.

c. Because the heating and cooling process of the annealing furnace is time-consuming and power-consuming, the forging production line matched with the waste heat annealing is preferably a saturated production line with three shifts, and at least two shifts must be ensured. Otherwise, the production is 8 hours and the empty furnace is running for 16 hours. of.

The above is the relevant introduction about the annealing heat treatment process of small gear forgings. You can comprehensively measure the quality, cost, delivery time, site and other factors of actual production, and choose a suitable forging annealing process.

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Analysis of technical characteristics of forged shaft forgings

Forging is a processing method that uses forging machinery to apply pressure to metal blanks to cause plastic deformation to obtain shaft forgings with certain mechanical properties, certain shapes and sizes. Forging and stamping belong to the nature of plastic processing, collectively referred to as forging. Forging is a common forming method in mechanical manufacturing. The as-cast looseness and welding holes of the metal can be eliminated by forging, and the mechanical properties of forgings are generally better than castings of the same material. For important parts with high load and severe working conditions in machinery, forgings are mostly used except for plates, profiles or weldments that can be rolled with simple shapes.

The recrystallization temperature of steel is about 460°C, but 800°C is generally used as the dividing line, and hot forging is above 800°C; it is called warm forging or semi-hot forging between 300 and 800°C.

Forging can be divided into cold forging and hot forging according to the temperature of the blank during processing. Cold forging is generally processed at room temperature, and hot forging is processed at a temperature higher than the recrystallization temperature of the blank metal. Sometimes it is also called warm forging when it is heated but the temperature does not exceed the recrystallization temperature. However, this division is not completely uniform in production.

According to the forming method, forging can be divided into free forging, die forging, cold heading, radial forging, extrusion, forming rolling, roll forging, rolling and so on. The deformation of the billet under pressure is basically not subject to external restrictions, which is called free forging, also known as open forging; the deformation of the billet in other forging methods is restricted by the mold, which is called closed mode forging. There is a relative rotational movement between the forming tools of forming rolling, roll forging, rolling, etc. and the blank, and the blank is pressed and formed point by point and gradually, so it is also called rotary forging.

Generally, round or square bars are used as blanks for small and medium-sized shaft forgings. The grain structure and mechanical properties of the bar are uniform and good, the shape and size are accurate, the surface quality is good, and it is convenient to organize mass production. As long as the heating temperature and deformation conditions are controlled reasonably, shaft forgings with excellent performance can be forged without large forging deformation.

Forging materials are mainly carbon steel and alloy steel with various components, followed by aluminum, magnesium, copper, titanium and their alloys. The original state of the material is bar stock, ingot, metal powder and liquid metal.

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How to determine the forging process plan?

Bearing sleeve trunnion

The purpose of economic analysis of forging processing is to explore technical solutions and pursue economic effects. Any production process must not only formulate the process, determine the process parameters and process equipment, but also discuss the economic effect.

The principle of determining the forging process is to create the most material wealth with less labor consumption. The optimization of the process is to find the minimum value in the total consumption of materials, equipment, energy and labor under the premise of ensuring product quality and quantity. For the forging process, it can be specifically: high dimensional accuracy of forgings, organization and performance meeting requirements; less raw material consumption, small equipment investment, simple tools, low energy consumption, low labor intensity, and no environmental pollution.

Techno-economic effects are carried out using the comparative method. When comparing process schemes, there may be more than two schemes. In order to make the analysis conclusion correct, an exhaustive method should be used to list possible schemes or alternative schemes. To this end, it is necessary to carry out forging process analysis, explore a variety of processes and schemes, and prepare conditions for technical and economic analysis and selection of process schemes. The tasks of general process analysis can be summarized as follows: according to the functional characteristics, materials, shapes, dimensional accuracy, quality requirements and production batches of parts, in the existing or available equipment, devices, tools, energy, inspection methods, management level and personnel Under the condition of quality, put forward various process schemes that can be used.

When conducting a process analysis, the following questions must be considered and answered:

Harvester axle

(1) Whether it can meet the function of the forging;

(2) Whether it can meet the technical requirements of drawings and quality standards;

(3) Whether the structure of the forging is reasonable and whether there is any excess dressing;

(4) Whether the residual collision can be reduced;

(5) Whether the deformation force or deformation function is reduced;

(6) Whether the metal streamline meets the requirements;

(7) Whether there are any omissions in the quality assurance process;

(8) Whether the processes and steps have been minimized;

(9) Whether the material is fully utilized, and whether it is possible to forge with other parts together, with multiple pieces in one mold or multiple pieces in one blank;

(10) Have you considered cold forging, precision forging, rolling, partial die forging, segmented die forging, combined die forging, forging and welding, etc.?

Bearing sleeve trunnion

According to the shape, size and deformation mode of the forging, calculate the deformation force, and select the main forging equipment. Determine the heating temperature according to the forging material and deformation method, and select the heating method and heating equipment. The blanking equipment is selected according to the type of forging equipment, the deformation method and the size of the blank. Determine the process route according to the quality requirements of the forgings, and select equipment such as trimming, calibration, tip pressure, heat treatment, cleaning, inspection, and flaw detection. Determine the production takt and productivity according to the production batch, and then calculate the number of equipment generations. According to equipment performance characteristics and productivity, calculate various consumption data, such as material, power, blanking, auxiliary material and mold consumption. According to the selected process, consider the production organization, equipment characteristics, determine the plant area required for production and the number of production workers, auxiliary workers, technical and management personnel. Then analyze the advantages and disadvantages of various processes, such as: labor conditions, environmental protection and its technical and labor skills needs.

Process analysis is a systematic engineering problem, so people who are engaged in this work are required to be familiar with the existing production methods, and master the characteristics, application scope and constraints of various process schemes. Can correctly calculate various technical parameters, understand the current situation, trends and development trends of forging production at home and abroad, and can infer and predict according to actual conditions.

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What is the difference between hot forging and cold forging?

Hinge

Forging transforms metal workpieces by compression at cold, hot or hot temperatures. Cold forging increases the strength of a metal by hardening it at room temperature. Hot forging achieves optimum yield strength, low hardness, and high ductility by hardening the metal at extremely high temperatures. Whether to use hot or cold forging depends on the function, industry and production volume of the finished part.

The difference between hot forging and cold forging

While cold forging compresses metal at room temperature, hot forging requires high temperatures. The main difference between cold forging and hot forging is that the high temperature of hot forging gives the metal a finer and more complex shape than cold forging.

Hot forging

The hot forging temperature varies depending on the metal type. Hot forging begins by heating the die to prevent any temperature loss during the process and to ensure that crystallization does not occur until the forming is complete. Heating makes the metal more ductile. When the pressure of the die squeezes the hot metal, the structure transforms into finer grains, which increase yield strength and ductility.

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Factors to consider when hot forging include:

Cool down

If the metal cools to a temperature below the minimum threshold, the forging is complete. If this happens before reaching the final shape, the metal must be reheated.

Tolerance

The dimensional tolerances of hot forging are not as precise as cold forging.

Specification

Hot forging dies are customized according to customer’s part specifications.

Cold forging

Cold forging uses a displacement process to shape the material into the desired shape. The compressive force squeezes the metal between the punch and die at room temperature until the material conforms to the contour of the die. Cold forging techniques include rolling, pressing, drawing, spinning, upsetting and extrusion.

Factors to consider when cold forging include:

Material volume

Careful control of material volume prevents stress and damage, especially in closed forging, as excess material has nowhere to escape.

Bonding

This coating process improves material flow during the process to reduce forces, stresses and friction while improving surface quality.

Annealing

Annealing softens metal and improves material flow. It can be applied as an intermediate process when work hardening occurs before the forging process is completed.

Lubricating

Lubrication is critical in the cold forging process. High-viscosity oil prevents metal-to-metal friction, and thin oil dissipates heat.

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Advantages and disadvantages of hot forging and cold forging

Advantages of hot and cold forging

Hot forging adds ductility to more complex parts and allows for more customization options; cold forging produces no waste, requires little finishing, maintains dimensional accuracy, and produces high surface quality.

Disadvantages of hot and cold forging:

Additional cost of hot forging heat treatment, less precise dimensional tolerances, risk of warpage; cold forging has few custom options, risk of residual stress, may require heat treatment.

The above is about the process difference between hot forging and cold forging. When choosing which forging process to use, you must understand its characteristics in advance.

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Detailed explanation of cold forging forming process

Pipe joint forgings

Cold forging is a general term for plastic processing such as cold die forging, cold extrusion, and cold heading. It is the forming process of the material below the recrystallization temperature, and the forging is carried out below the recovery temperature. In production, forging without heating the blank is called cold forging.

Most of the cold forging materials are aluminum and some alloys, copper and some alloys, low carbon steel, medium carbon steel, and low alloy structural steel with low deformation resistance and good plasticity at room temperature. Cold forgings have good surface quality and high dimensional accuracy, which can replace some cutting processes. Cold forging can strengthen the metal and increase the strength of the part.

Introduction of cold forging process

Locomotive forgings

Cold precision forging is a (near) net shape forming process. The parts formed by this method have high strength and precision and good surface quality. At present, the total amount of cold forgings used in an ordinary car abroad is 40~45kg, of which the total amount of toothed parts is more than 10kg. The single-piece weight of cold forged gears can reach more than 1kg, and the tooth shape accuracy can reach 7 grades.

Continuous process innovation has promoted the development of cold extrusion technology. Since the 1980s, domestic and foreign precision forging experts have begun to apply the split forging theory to the cold forging of spur and helical gears. The main principle of shunt forging is to establish a shunt cavity or shunt channel of material in the forming part of the blank or die.

During the forging process, while the material fills the cavity, part of the material flows to the shunt cavity or shunt channel. The application of shunt forging technology enables the less and no cutting processing of higher precision gears to quickly reach an industrial scale. For extruded parts with a length-diameter ratio of 5, such as piston pins, cold extrusion can be achieved at one time by axial shunt by using a wide range of axial residual blocks, and the stability of the punch is very good; for flat spur gears Forming, the use of radial residual blocks can also achieve cold extrusion forming of products.

Locking frame forgings

Blocked forging is to extrude metal in one or two directions through one or two punches in a closed die at one time to obtain near-net shape precision forgings without flash. If some car precision parts such as planetary and half shaft gears, star sleeves, cross bearings, etc. are processed by cutting, not only the material utilization rate is very low (less than 40% on average), but also it takes a lot of man-hours and the production cost is extremely high. These net shape forgings are produced in foreign countries using occlusion forging technology, which saves most of the cutting process and greatly reduces the cost.

Advantages and disadvantages of cold forging

Limit wear plate

Cold forging process is a precision plastic forming technology, which has unparalleled advantages of cutting, such as good mechanical properties, high productivity and high material utilization rate of products, especially suitable for mass production, and can be used as a manufacturing method for final products. , It has a wide range of applications in industries such as transportation, aerospace and machine tool industries.

Material requirements are high; not suitable for small amounts of processing; mold requirements are high.

The above is a detailed introduction to the cold forging process. The forming accuracy of cold forging technology is higher than that of warm forging and hot forging, and it has its unique advantages in the field of precision forming. The application of the cold forging process improves the bore finish, dimensional accuracy and surface strength, prolongs the life of the barrel, and improves the shooting accuracy of the gun accordingly, and it is easy to process the tapered barrel and reduce the quality.

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What are the basic processes of free forging?

Pipe joint forgings

Free forging is a processing method that uses impact force or pressure to deform the metal freely in all directions between the upper and lower anvil surfaces, and obtains the required shape and size and certain mechanical properties without any restriction, which is referred to as free forging. The tools and equipment used in free forging are simple, versatile and low in cost. Compared with casting blanks, free forging eliminates shrinkage holes, shrinkage porosity, pores and other defects, so that the blanks have higher mechanical properties. Forgings are simple in shape and flexible in operation. Therefore, it has special significance in the manufacture of heavy machinery and important parts.

Basic process of free forging

The basic processes of free forging include upsetting, drawing, punching, bending, torsion, offset, cutting and forging.

Upsetting

A forging process that reduces the height of the blank and increases the cross-sectional area. The upsetting process is mainly used for forging gear blanks and round cake forgings. The upsetting process can effectively improve the blank structure and reduce the anisotropy of mechanical properties. Repeated upsetting and drawing can improve the morphology and distribution of carbides in high-alloy tool steels.

Agricultural machinery bearing sleeve

Upsetting mainly has the following three forms:

1. Complete upsetting. Complete upsetting is to place the blank vertically on the anvil surface, and under the hammering of the upper anvil, the blank will be plastically deformed with a height reduction and an increase in the cross-sectional area.

2, the end upsetting. After the billet is heated, one end is placed in a drain or mold to limit the plastic deformation of this part, and then the other end of the billet is hammered to make it upsetting. The upsetting method of the leaking disc is mostly used for small batch production; the method of upsetting the tire mold is mostly used for mass production. Under the condition of single-piece production, the part that needs upsetting can be heated locally, or after all heating, the part that does not need upsetting can be chilled in water, and then upsetting is performed.

3. Upsetting in the middle. This method is used for forging forgings with large middle section and small sections at both ends. For example, gear blanks with bosses on both sides are forged by this method. Before the upsetting of the billet, both ends of the billet should be thinned first, and then the billet should be upright in the middle of the two leakage pans for hammering to make the middle part of the billet upsetting. In order to prevent the billet from bending during upsetting, the ratio of the billet height h to the diameter d h/d ≤ 2.5.

Pull out

Elongation, also known as elongation, is a forging process that reduces the cross-sectional area of ​​the billet and increases its length. Drawing length is often used for forging rods and shaft parts. There are two main methods of pulling out:

1. Pull out on the flat anvil.

2. Pull out on the mandrel. During forging, the mandrel is first inserted into the punched billet, and then drawn as a solid billet. When drawing long, it is generally not drawn at one time. First, the blank is drawn into a hexagonal shape, and after forging to the required length, the chamfer is rounded and the mandrel is taken out. In order to facilitate the removal of the mandrel, the working part of the mandrel should have a slope of about 1:100. This drawing method can increase the length of the hollow blank, reduce the wall thickness, and keep the inner diameter unchanged. It is often used for forging long hollow forgings such as sleeves.

Harvester pusher

Punching

There are two main methods of punching:

1. Double-sided punching method. When the punch is punched to the depth of 2/3 to 3/4 on the blank, take out the punch, turn the blank, and then use the punch to align the position from the reverse side to punch out the hole.

2. Single-sided punching method. For blanks with small thickness, single-sided punching method can be used. When punching, the blank is placed on the backing ring, the big end of a slightly tapered punch is aligned with the punching position, and the blank is hammered into the blank until the hole penetrates.

Bending

The forging process in which a certain tool and die bends the blank into a specified shape is called bending.

There are two commonly used bending methods:

1. Forging hammer compression bending method. One end of the blank is pressed by the upper and lower anvils, and the other end is struck with a sledgehammer or pulled by a crane to bend it into shape.

2. Die bending method. Bending in the pad die can obtain small forgings with more accurate shape and size.
Cutting refers to the forging process in which the blank is divided into several parts or partially cut, or a part is cut from the outside of the blank, or a part is cut from the inside.

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Twist

Torsion is a forging process that rotates one part of wool by an angle about its axis relative to another. This process is mostly used for forging multi-turn crankshafts and correcting some forgings. When the torsion angle of the small billet is not large, the hammering method can be used.

Misplaced

Staggering refers to the forging process in which one part of the blank is staggered parallel to another part by a distance, but the axis is still kept parallel. It is often used for forging crankshaft parts. When staggered, the blank is first cut locally, and then impact force or pressure of equal size, opposite method and perpendicular to the axis is applied on both sides of the incision, so that the blank can be offset.

Forging

Forging is a forging process in which the billet is heated to a high temperature in a furnace, and then struck with a hammer to combine the two in a solid state. Forging methods include lap joint, butt joint, snap joint and so on. The strength of the seam after forging can reach 70% to 80% of the strength of the connected material.

The above is all about the basic process of free forging. I hope it can be helpful to everyone. If you have any questions during the operation, you can contact us at any time.

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What are the advantages and disadvantages of free forging?

Forgings

Free forging is what we call free forging, which is completed by gradual local deformation of the blank on the flat anvil or between the tools. Because the tool is in contact with the blank part, the stagnant grid work is much smaller than the die forging bar for the production of forgings of the same size, so free forging is suitable for forging large forgings. Of course, free forging also has certain advantages and disadvantages in the forging process. Yes, let’s find out together!

Agricultural machinery lifting arm

The advantages of free forging :

(1) Free forging can improve the structure and properties of metal. The quality and mechanical properties of metal free forgings are higher than those of castings, and their strength is 50% -70% higher than that of castings, so they can withstand large impact loads. Forgings can reduce the weight of the parts themselves on the premise of ensuring the design strength of the parts, which is of great significance to aerospace and transportation.

(2) Free forging can save raw materials. Parts with shapes closer to the part can be produced using the free forging method.

(3) Free forging is suitable for single-piece small batch production, and the variety is more flexible.

(4) Since there is no lateral flow in the straight shaft or curved shaft parts and annular parts, the streamline distribution is generally more reasonable than that of die forgings. It is especially suitable for straight or curved shafts, discs or rings with simple shape, small cross-section change and gentle main axis.

(5) Some special quality torsion requirements can be met by the free forging process, such as reverse upsetting can improve the quality of raw materials.

Other agricultural machinery forgings

The disadvantages of  free forging:

(1) Compared with die forging, the material utilization rate of free forgings is low, and the machining area is larger. The clarity and straightness of the flow pattern and the degree of agreement along the outer contour of the forging are worse than those of die forgings. During the machining process, Metal streamlines are easily cut.

(2) Compared with die forgings, the mechanical properties of aluminum alloy free forgings are relatively low.

(3) The forging production method has lower production efficiency than other pressure processing methods, and the degree of mechanization and automation needs to be improved.

(4) The degree of forging deformation is not uniform enough. The uniformity of the shape and size of the same batch of forgings is worse than that of die forgings. Due to the comparison of fire, complex forgings are only heated and do not participate in deformation in some parts. Therefore, it may be It leads to the appearance of inhomogeneous structure or low magnification coarse grains.

(5) Compared with die forging, the quality of free forgings is more affected by the forging process and the level of forging operations.

The above is all about the advantages and disadvantages of free forging. In fact, there are various forging processes, which should be selected according to the actual forging needs. Different processes have different advantages and disadvantages, and must be understood in advance.

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What are the main factors affecting the quality of die forgings?

Agricultural machinery lifting arm

The die forging process has high production efficiency, low labor intensity, accurate dimensions, small machining allowance, and can forge forgings with complex shapes; it is suitable for mass production. However, the cost of the die is high, and special die forging equipment is required, which is not suitable for single-piece or small batch production. Therefore, the quality of die forgings is also more concerned by users. Correctly understand the main factors affecting the quality of die forgings. very important meaning.

The main factors affecting the quality of die forgings

Other agricultural machinery forgings

1. Defects in raw materials

For example, there are residual shrinkage holes, bubbles, porosity, inclusions, etc. in the ingot or steel, which may cause the forging to crack. Forging cracks caused by metallurgical reasons are often accompanied by a large number of oxides, sulfides, silicates and other inclusions. The raw materials of high carbon and high alloy steel are prone to serious segregation of second phases such as carbides. If they are not crushed and evenly distributed during forging, the mechanical properties of the forgings will be reduced, and the forgings may be cracked or evenly distributed during heat treatment. distortion. If there are scratches, scars, folds and cracks on the surface of the raw material, it will bring defects to the forgings. Therefore, raw materials must be inspected in die forging production.

2. Heating specification

When forging large die forgings and alloy steel die forgings, if the heating speed is too fast, the temperature difference between the inner and outer layers will be large, and the central part will be cracked due to temperature stress and structural stress.
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When the heating temperature is too high and the holding time is too long to cause slight overheating, a lustrous, crystalline, and intergranular fracture will be produced. Coarse grains that are slightly overheated can be corrected by annealing or normalizing, followed by recrystallization. In severe overheating, fractures or stone fractures will occur. The characteristics of the fracture are fish-scale bright spots and transgranular fracture; the reason for the fracture is that the coarse austenite grains form an intragranular texture with extremely high stability. Texture characteristics are preserved.

Harvester pusher

The stone-like fracture has obvious coarse crystals, the surface has no metallic luster, the color is gray, and the intergranular fracture is caused. Saturated coarse austenite precipitates, surrounding austenite grains to form brittle crystal shells. Severely overheated forging billets have extremely poor mechanical properties. The naphthalene-shaped fracture can be normalized at high temperature to eliminate the intragranular texture, while the stone-shaped fracture is difficult to be corrected by heat treatment.
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The forging heating temperature is low, and when the heat is not penetrated, cracks with transgranular propagation may occur, and the tail ends are sharp. When there is no subsequent heating process, there is no oxidation and decarburization on the surface of the cracks.
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For alloy structural steel, if the final forging temperature is too high, the austenite will continue to grow after final forging, even exceeding the original grain size. Coarse-grained fractures can be seen in fracture inspection, and Widmanderin microstructure appears in high magnification observation. If the final forging temperature is too low, the steel is in the dual-phase region, the inclusions are distributed along the main deformation direction of the blank, and the ferrite precipitated from the austenite preferentially adheres to the surface of the inclusions to form a banded structure. Widmanderin and banded structures reduce the mechanical properties of forgings, especially the impact toughness. In order to refine the grains, improve the structure, and improve the mechanical properties, the steel with such a structure must be completely annealed to recrystallize it.

3. Die forging process

Different forms of die forging are used, such as open die forging, closed die forging, extrusion, upsetting, high-speed die forging, rolling, etc. The essence is to apply different forms to the blank through corresponding die forging equipment and dies. The thermal and mechanical conditions make it produce different physical fields and evolution processes of tissue properties. For the same forging, whether the selection of the deformation method is reasonable or optimal, the quality of the die forgings is very different. The wrong selection may make the forming process impossible, and the unreasonable selection will make the forming difficult and prone to many quality problems.

Cam forging

The die forging process parameters such as deformation temperature, deformation speed and degree of deformation are obviously directly related to the quality of die forgings. For example, for ingots or some materials, it is necessary to compact the structure and refine the grains through deformation. If the forging deformation is small, the expected effect cannot be obtained; some non-ferrous metals, especially high-strength aluminum alloys, magnesium alloys, etc. , requires a small deformation speed and an appropriate degree of deformation, and is suitable for forming on a press, which helps to avoid cracks.

The quality of die forgings is also related to forging design and forging die design. The selection of machining allowance and forging tolerance should be based on reality. If the specification is too small, it is easy to cause waste after machining due to surface defects and dimensional errors. Whether the design of the structure and the flash structure is appropriate will affect the flow and filling quality of the metal; if the setting of the lock is ignored, the size of the forging will be out of tolerance due to the misalignment of the upper and lower dies. In addition, the installation and tightening, preheating, cooling and moistening of the forging die should comply with the specifications, and the violations should be checked at any time and corrected in time.

The above is all about the factors affecting the quality of die forgings. Every link in the production of die forging will have a non-negligible impact on the quality of the forgings. Strictly follow the relevant quality inspection and control in the production process to ensure the quality of the die forgings.

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What are the commonly used forging equipment?

Forging equipment

In forging processing, forging equipment is mainly used for metal forming and metal separation, so it can also be called metal forming machine tool. The forming principle of forging equipment is to exert pressure on the metal, and the large impact force is the main feature of this type of equipment. Therefore, in order to ensure the normal operation of the equipment and the personal safety of operators, various safety protection devices will be installed on the equipment.

There are many types of forging equipment, which can be divided into forming equipment and auxiliary equipment. The forming equipment includes forging hammers, mechanical presses, hydraulic presses, screw presses, and flat forging machines. machine etc. In the current processing industry, hammer forging equipment, hot die forging press, screw press, flat forging machine, hydraulic press, etc. are commonly used forging equipment in forging workshops.

Forging equipment–forging hammer

Among the forging equipment, the most widely used equipment is the non-forging hammer. When the forging hammer is working, after the high-speed movement generates kinetic energy through the falling of the heavy hammer or the processing external force, the processed blank is forged to plastically deform the product. The forging hammer has the characteristics of simple structure, flexible work, wide application and easy maintenance, and can be used for free forging and die forging.

Forging equipment

Forging Equipment–Hot Forging Press

Hot die forging press is a very commonly used high-precision forging equipment in modern forging production. It can be used to produce large quantities of die forging and finishing forgings of ferrous and non-ferrous metals. The forgings produced by this processing method have higher precision and can be It uses raw materials to a greater extent, has a high degree of automation, and is easy to operate, which greatly improves the production efficiency of products. It is widely used in automobiles, ships, aviation, mining machinery, petroleum machinery, hardware tools and other manufacturing industries.

Forging equipment–screw press

Screw presses, according to their processing methods, can be divided into two types, one is a device that generates static pressure by applying torque to the bolt, and the other is a device that generates pressure through the rotation of the flywheel device on the bolt, and the metal blank is once forming equipment.
The screw press is mainly used for the processing of various high, medium and low-grade refractory materials. Forging, casting and forging.

Forging Equipment–Flat Forging Machine

Horizontal forging machine is a flat forging machine. It can be used to produce die forgings. This equipment adopts the method of local upsetting, which can realize the work of punching, bending, flanging, trimming and cutting. Flat forging machines have high productivity and can be used for mass production. Widely used in automobile, tractor, bearing and aviation industries.

Forging equipment–hydraulic press

Hydraulic presses, as the name suggests, are equipment for processing metal, plastic, rubber, wood, powder and other blanks through hydrostatic pressure. The hydraulic press used for forging is generally a hydraulic press with a high tonnage.

The hydraulic press is suitable for various processes such as bending, forming and flanging of central load parts. When used with a punching buffer device, it can also perform punching and blanking processing. The use of hydraulic presses in ships, pressure vessels, chemical industries and other industries will be more many.

The above content mainly introduces the commonly used forging equipment in the processing industry. If you need other forging related knowledge such as forging category, forging process, forging characteristics, etc., you are welcome to call the 24-hour consultation hotline, the company’s official website: www.gold-emperor. com.

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What are the common forging processes?

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Forging is the use of forging pressure on metal blank products by forging machines to plastically deform the processed forgings to achieve specific mechanical properties, shapes and sizes. This is an important metal plastic processing method adopted by many forging manufacturers. Many people know about forging, but they don’t know much about the forging process. Today, GOLD EMPEROR FORGING, a forging manufacturer, will share with you some common forging processes.

Classification according to forging temperature:

First of all, the forging process can be classified according to the forging temperature, commonly used are hot forging, warm forging and cold forging.

Classification according to forming principle:

Secondly, we can also divide the forging process into free forging, die forging, ring rolling and special forging according to the forming principle of forgings.

forging process

1. Free forging of forging process

Using simple universal tools, or directly applying external force to the blank between the upper and lower anvils of the forging equipment, the blank is deformed, and the processing method of the forging to obtain the required geometric shape and internal quality is free forging. Forgings produced by the free forging method can be called free forgings. Free forging is mostly used to produce small batches of forgings. We can use forging equipment such as forging hammers and hydraulic presses to form and process the blanks to obtain qualified forgings. The basic processes of free forging include upsetting, drawing, punching, cutting, bending, torsion, offset and forging. Free forging is all hot forging.

2. Die forging of forging process.

Die forging can be divided into open die forging and closed die forging. After the metal blank is compressed and deformed in a forging die cavity with a certain shape, the required forgings can be obtained. Die forging is mostly used to produce important light and large-scale parts.

Die forging can be divided into hot forging, warm forging and cold forging. In the future, warm forging and cold forging will use more die forging processes, which are more difficult to forge than other forging methods, and can better reflect the forging technology level of forging manufacturers.

According to forging materials, die forging can also be divided into ferrous metal die forging using ferrous metals such as carbon steel, non-ferrous metal die forging using non-ferrous metals such as copper and aluminum, and powder product forming with powder metallurgy materials.

forging process

3. Rolling ring of forging process.

Ring rolling refers to the method of forging and processing ring parts of different diameters using special equipment such as ring rolling machines. This method can be used to produce wheel-shaped parts such as automobile hubs and train wheels.

4. Special forging of forging process.

Special forging mainly refers to forging methods such as roll forging, cross wedge rolling, radial forging, liquid die forging, etc. These methods can be used to produce forgings with special shapes.
For example, roll forging can be used as an effective preforming process to greatly reduce the subsequent forming pressure; cross wedge rolling can produce parts such as steel balls and drive shafts; radial forging can produce large forgings such as barrels and stepped shafts.

The above is the introduction of common forging processes organized by the forging manufacturer–GOLD EMPEROR FORGING. I hope it can help you! We are a forging supplier from China, specializing in the forging of auto parts, construction machinery parts, mining equipment parts, electromechanical forgings and other products, providing a full range of forging services for customers who need to use various forgings.

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