Gear forgings, as the name suggests, are a kind of gear produced by forging technology. The performance of gear forgings will be more stable, and the damage rate will be reduced a lot during operation, so the demand for gear forgings is very large.

Gear forgings are also a kind of forging products. When forging, it needs to be carried out according to the rules. At the same time, some hard technical requirements need to be met. Now forging manufacturers will introduce the technical requirements of gear forgings.

1. The allowance size of gear forgings should conform to national standards.

2. Gear forgings should ensure a suitable forging ratio during forging, and should not be forged with round steel of similar size.

3. Do not use billet forging.

4. The material of gear forgings should be consistent with the material of the parts, and the chemical composition should meet the national standard. And issue a bill of materials.

5. To ensure normal forging temperature, not forging at low temperature or over-burning.

6. The shape of the forgings should be neat and uniform, and no forging defects such as stacking and breaking are allowed.

7. Ultrasonic flaw detection shall be done after rough turning of forgings. Gears shall not exceed φ3 equivalent, and others shall not exceed φ4 equivalent. The inspection report shall prevail.

8. Normalizing after forging.

9. Write the part number with paint on the forging.

The above content is the technical requirements that we need to meet when we carry out gear forging. From the introduction of this article, you should have a general understanding. Gear forgings are still widely used, and are generally used in various machinery. Finally, learning to use gear forgings correctly can extend the actual service life.

Aluminum alloy has begun to be used more and more in the electric vehicle industry. At the same time, aluminum alloy material is also the most widely used metal in all walks of life. The output of aluminum alloy is second only to steel. Aluminum alloys generally have processes such as casting, forging and die casting in the industry.

Different processes meet different application requirements. Among them, aluminum alloy forging has a series of excellent characteristics. After forging, the metal structure of the aluminum alloy can be changed, and the performance of the aluminum alloy can be effectively improved.

Characteristics of aluminum alloy forging

First of all, the internal organization is fine, uniform and defect-free, and its reliability is far away. It can be processed into high-precision forging with complex shapes, and the machining allowance is small, only about 20% of the machining allowance of the aluminum alloy drawing thick plate, which greatly saves man-hours and costs. Second, the thermal conductivity is good.

The forging temperature range is narrow, and the requirements for the forging temperature are always strict. The performance characteristics of heating die forging are that the aluminum alloy does not produce allotropic transformation. It mainly depends on the correct control of the forging mechanical parameters to improve the metal structure, so that the metal streamline is uniformly and continuously distributed along the forging shape. to improve mechanical properties.

Forged aluminum wheels have high density, no porosity, pinholes, and no pores on the surface, and have good surface treatment performance. The coating is uniform and consistent, with high bonding force, and the color is harmonious and beautiful. Forged aluminum wheels have good machinability. It can be seen that forged aluminum wheels have light weight, high specific strength, good toughness, fatigue resistance and corrosion resistance, good thermal conductivity, and easy machining.

Based on the above characteristics of aluminum alloy forging, if the electric vehicle needs to reduce the weight of the whole vehicle, then the steering wheel connecting plate can be made of aluminum alloy forging process, and the rear shock absorber can also be made of aluminum alloy material. Can greatly reduce the weight of the vehicle. The whole front fork of the following products is only 2.85kg, and the rear fork is only 1.35kg.

Aluminum alloy forging process

Forging production occupies a very important position in the industrial industry. Aluminum alloy is also a commonly used material in forging. All kinds of forging that can be forged with low carbon steel can be forged with aluminum alloy. Most of the alloy forged parts are safety parts, and they are mass-produced, so the inherent quality requirements of aluminum alloy materials are very high.

Forged aluminum alloy parts generally go through the following main manufacturing processes: alloy smelting – casting – extrusion – forging – heat treatment – machining. Alloy smelting composition distribution ratio, degassing, filtration, casting reverse segregation, extrusion process quality, forging (aluminum alloy forging) metal streamline, heat treatment temperature, time, grain size control, dimensional accuracy, etc., require a very systematic process control to achieve stability.

Forging is a processing method that uses a forging machine to apply pressure to a metal blank to plastically deform it to obtain a forging with certain mechanical properties, certain shape and size. Forging (forging and stamping) is one of the two major components.

Through forging, defects such as as-cast looseness produced by the metal during the smelting process can be eliminated, and the microstructure can be optimized. At the same time, due to the preservation of the complete metal streamline, the mechanical properties of forgings are generally better than those of castings of the same material. So do you know the three basic principles in the forging process? Below, the relevant personnel of Chinese professional forging manufacturers will give you a detailed introduction, let’s learn about it together!

1. The principle of constant volume

When forging each forging, the material should be calculated first, and the material should be cut according to the weight and fire consumption of the forging. (The basic formula for calculating the material G = ρV G – the weight of the billet ρ – the specific gravity of the material V – the volume of the billet) When calculating the material, the volume of the raw material must be calculated (due to the different specific gravity of various raw materials) and then multiplied by the specific gravity to get the forgings The weight of any forging is closely related to the volume before and after forging, such as pier thickening, drawing length, punching, mandrel drawing length, shoulder pressing, misalignment, bending and twisting during forging. Its overall volume remains the same, but the shape is changing, such as from a circle to a square, from a square to a circle, from an octagonal to a circle, etc., but the volume remains unchanged.

2. The principle of least resistance

Before forging, specifying the process and selecting equipment must consider the deformation law of the workpiece. There are three categories of basic process, auxiliary process and shaping process in free forging.

For example, if the pier is thick: the workpiece is axially stressed and has no radial resistance, and it changes from the axial direction to the radial flow. The greater the axial resistance, the faster the radial flow. The smaller the axial resistance, the slower the radial flow.
Lengthening: Rectangular section and circular section are elongated, mainly due to the amount of feed and reduction. If the upper and lower flat anvils are used for lengthening, the narrower the width of the anvil, the smallest axial resistance, while the longitudinal resistance is large. , so the axial flow is larger than the longitudinal flow.

V-shaped anvil pulling: If the upper and lower V-shaped anvils are used for pulling (referring to the round material), the lateral flow is restricted, and the metal is forced to flow in the axial direction, and the pulling speed is increased. The same is true for the upper and lower semicircular anvils falling round.

Horse bar reaming: During the forging process of horse bar reaming, the contact surface between the upper anvil and the workpiece and the horse bar is small, resulting in the influence of friction, the resistance is small, the wall thickness is reduced, and the inner and outer diameters are enlarged.

Lengthening of the mandrel: Generally, the four angles of the upper and lower V-shaped anvils are used to generate resistance, and the contact surface between the workpiece and the tooling is reduced, forcing the metal to flow along the axial direction and increasing the length. Therefore, the principle of minimum resistance is inseparable from the principle of minimum resistance when formulating the process and selecting tooling in the forging process.

3. Principles of stress and elasticity

This principle is mainly used for the workpiece after forging, heating, cooling and heat treatment, the formulation of the workpiece after forging, the final forging temperature of the workpiece after forging and the material of the workpiece, and the shrinkage force is not equal. The internal stress of the workpiece is formulated, the cooling system after breaking and the heat treatment specification. This principle is very important.

Stress includes: temperature stress (thermal stress), tissue stress, residual stress. When processing large forgings, the larger the rectangular section and the circular section, the more prominent the thermal stress, stress and residual stress. When the billet is heated, the greater the temperature difference between the inside and outside, the greater the thermal stress generated. Therefore, when heating large forging blanks, the temperature must be fully and uniformly heated through, and the temperature must be strictly controlled.

Strain stress: Forging the workpiece is mainly to break the as-cast structure and refine the grains. When the deformation reaches a certain level, the as-cast coarse grains, dendrites and grain boundary substances are broken. The workpiece is deformed, yielded, closed, pressed, welded, and compacted. After reasonable forging, the compactness, continuity and mechanical properties of the workpiece can be significantly improved, but the workpiece will generate its own structural deformation stress during forging. When the pressure is super high, the deformation stress that occurs is super strong. Cold rolls such as 9Cr2Mo perform particularly well during heating and post-forging heat treatment.

Residual stress: It is the general term for the residual stress after heating and forging. Often appear in large and medium forgings. In particular, forgings must be strictly checked and strictly required in the next step after forging. It is crucial to the quality assurance of forgings.

The above three principles are very important, and they are also the basic knowledge that every forging person must master. To become a qualified blacksmith.

Forging is a processing method that uses a forging machine to apply pressure to a metal blank to plastically deform it to obtain a forging with certain mechanical properties, certain shape and size. Forging (forging and stamping) is one of the two major components. Through forging, defects such as as-cast looseness generated in the metal smelting process can be eliminated, and the microstructure can be optimized. At the same time, due to the preservation of the complete metal streamline, the mechanical properties of forgings are generally better than those of castings of the same material. For important parts with high load and severe working conditions in related machinery, forgings are mostly used in addition to rolling plates, profiles or welded parts with simple shapes.

The initial recrystallization temperature of steel is about 727 °C, but 800 °C is generally used as the dividing line, and hot forging is higher than 800 °C; between 300 and 800 °C, it is called warm forging or semi-hot forging. called cold forging.

Forgings used in most industries are hot forging. Warm and cold forging are mainly used for forging parts such as automobiles and general machinery. Warm and cold forging can effectively save materials.

Process classification

According to the forging temperature, it can be divided into hot forging, warm forging and cold forging.

According to the forming mechanism, forging can be divided into free forging, die forging, ring rolling and special forging.

1. Free forging

It refers to the processing method of forgings that use simple universal tools or directly apply external force to the blank between the upper and lower anvils of the forging equipment to deform the blank to obtain the required geometric shape and internal quality. Forgings produced by the free forging method are called free forgings. Free forging is mainly based on the production of small batches of forgings. Forging equipment such as forging hammers and hydraulic presses are used 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.

Advantages: Free forging has the characteristics of flexible process, high versatility of equipment and tools, and low cost. Since free forging is formed gradually, the required deformation force is small, so it is the only way to produce large forgings (above 300T).

Disadvantages: low productivity, low precision forgings, high labor intensity, mostly used for single-piece and small batch production of forgings with simple shapes and low precision requirements.

2. Die forging

Die forging is divided into open die forging and closed die forging. The metal blank is compressed and deformed in a forging die cavity with a certain shape to obtain a forging. Die forging is generally used to produce parts with small weight and large batches. Die forging can be divided into hot forging, warm forging and cold forging. Warm forging and cold forging are the future development direction of die forging, and also represent the level of forging technology.

According to the material, die forging can also be divided into ferrous metal die forging, non-ferrous metal die forging and powder product forming. As the name implies, the materials are ferrous metals such as carbon steel, non-ferrous metals such as copper and aluminum, and powder metallurgy materials. Extrusion should belong to die forging, which can be divided into heavy metal extrusion and light metal extrusion.

Closed die forging and closed upsetting are two advanced processes of die forging. Since there is no flash, the utilization rate of materials is high. It is possible to complete the finishing of complex forgings in one or several operations. Since there is no flash, the stressed area of ​​the forging is reduced and the required load is also reduced. However, it should be noted that the blank cannot be completely restricted. For this reason, the volume of the blank should be strictly controlled, the relative position of the forging die should be controlled and the forging should be measured, and efforts should be made to reduce the wear of the forging die.

3. Rolling ring

Ring rolling refers to the production of ring-shaped parts of different diameters through special equipment ring-grinding machines, and is also used to produce wheel-shaped parts such as automobile hubs and train wheels.

4. Special forging

Special forging includes roll forging, cross wedge rolling, radial forging, liquid die forging and other forging methods, which are more suitable for the production of parts 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.

Forging die

According to the movement mode of the forging die, forging can be divided into pendulum rolling, pendulum rotary forging, roll forging, cross wedge rolling, ring rolling and skew rolling. Pendulum rolling, pendulum swaging and ring rolling can also be processed by precision forging. In order to improve the utilization rate of materials, roll forging and cross-rolling can be used as front-end processing of slender materials. Rotary forging, like free forging, is also locally formed, and its advantage is that it can be formed with a small forging force compared to the size of the forging. In this forging method, including free forging, the material expands from the vicinity of the die surface to the free surface during processing, so it is difficult to ensure accuracy. The forging force can be used to obtain products with complex shapes and high precision, such as forgings such as steam turbine blades with many varieties and large sizes.

The movement of the die and the degree of freedom of the forging equipment are inconsistent. According to the deformation limitation characteristics of the bottom dead center, the forging equipment can be divided into the following four forms:

1. The form of limiting forging force: hydraulic press that directly drives the slider.

2. Quasi-stroke limit method: hydraulic press that drives the crank connecting rod mechanism.

3. Stroke limitation method: mechanical press with crank, connecting rod and wedge mechanism driving the slider.

4. Energy limitation method: use the screw and friction press of the screw mechanism.

In order to obtain high precision, care should be taken to prevent overload at the bottom dead center, and to control the speed and mold position. Because these will have an impact on forging tolerances, shape accuracy and forging die life. In addition, in order to maintain the accuracy, attention should also be paid to adjusting the clearance of the slider guide rail, ensuring the rigidity, adjusting the bottom dead center and using the auxiliary transmission device.

Slider

There are also vertical and horizontal motions of the slider (for forging of slender parts, lubricating cooling and forging of parts for high-speed production), and the compensation device can be used to increase the motion in other directions. The above methods are different, and the required forging force, process, material utilization, output, dimensional tolerance and lubrication and cooling methods are different, and these factors are also factors that affect the level of automation.

Different forging methods have different processes. Among them, the process of hot die forging is the longest, and the general order is: blanking of forging billet; heating of forging billet; roll forging preparation billet; die forging forming; trimming; punching; straightening; Intermediate inspection to check the size and surface defects of forgings; heat treatment of forgings to eliminate forging stress and improve metal cutting performance; cleaning, mainly to remove surface oxide scale; correction; inspection, general forgings are subject to appearance and hardness inspections, important forgings also It must undergo chemical composition analysis, mechanical properties, residual stress and other inspections and non-destructive testing.

Forging is one of many materials processing methods.

Forging is generally a volume forming process in which a machine part or a blank close to the part size is obtained by transferring and distributing the metal volume. The forged product is called a forging. Forging is mostly carried out under heating. The metal material is formed into a shape by forging, and the desired shape and size can be obtained, and the internal structure thereof can be remarkably improved, and the use performance is improved. Therefore, various parts or components that are subjected to large and complex loads are generally produced by a forging method.

Forging is usually divided into two categories: free forging and die forging.

Free forging is generally performed on free forging equipment using a simple tool to forge metal ingots or blocks into specific shapes and sizes. Free forging is mainly used for single-piece and small-volume production. As the demand for batches increases, the tools used are becoming more complex, resulting in tire die forging. Forging workshops of various types of mechanical repairing factories are mostly produced by free forging and tire die forging. Large forgings (such as large steam turbine rotors and turbines, giant wheels and aircraft engine crankshafts) required to manufacture critical load-bearing parts in heavy-duty machines also require free forging on large hydraulic presses.

Die forging is a forging method suitable for mass production of forgings. In the case of die forging, a forging die having a cavity (mold) having the same or similar shape as the forging is used, the forging die is mounted on the forging machine, the metal blank is placed in the die of the forging die, and the forging machine is passed. The forging die applies a load to the blank to plastically deform the blank, and the deformation flow is controlled by the die space. Die forging is also often introduced into a variety of volume forming methods for the production of forgings, such as extrusion, roll forging, cross rolling, etc. can be included in the scope of die forging.

In addition to high productivity, die forging also has the advantages of accurate shape and size of forgings, high material utilization, more reasonable streamline distribution, high service life of parts, and easy production and operation.