Agricultural machinery bearing sleeve

The forging products of the forging factory are plastically deformed by forging processing. The forging process is a processing method for the blanks or parts that use the external force to plastically deform the forging raw materials and obtain the size, shape and performance required for the forgings. Through forging processing can eliminate defects such as as-cast looseness caused by metal in the smelting process, optimize the microstructure, and at the same time greatly enhance the performance of forgings in use due to the preservation of the complete metal forging flow line.

Forging is one of the main methods for the production of blanks and parts in mechanical manufacturing. It is often divided into free forging and die forging. Compared with other processing methods, forging processing has the following characteristics:

1. Improve the internal structure of forgings and improve mechanical properties. After the forging blank is forged, its structure and properties are improved and improved. Forging processing can eliminate defects such as pores, shrinkage cavities and dendrites in the metal ingot, and can be coarsened due to plastic deformation and recrystallization of the metal. The grain is refined to obtain a dense metal structure, thereby improving the mechanical properties of the forging. In the design of the part, if the direction of the force of the part and the direction of the fiber structure are correctly selected, the impact resistance of the forging can be improved.

2. The utilization rate of materials is high. Metal plastic forming is mainly rearranged by the relative position of the metal body structure without the need to cut the metal.

3. Higher productivity. Forging processing is generally carried out by using a press and a forging hammer.

4. The accuracy of blanks or forgings is high. With advanced technology and equipment, it can achieve less or no cutting.

5. The metal material used for forging should have good plasticity so that it can be plastically deformed without breaking under the action of external force. Among the commonly used metal materials, cast iron is a brittle material with poor plasticity and cannot be used for forging. Copper, aluminum and alloys thereof in steel and non-ferrous metals can be processed under cold or hot conditions.

6. It is not suitable for forming forgings with complex shapes. Forging processing is formed in the solid state. Compared with casting, the flow of metal is limited, and it is generally required to adopt heating and other technological measures. It is difficult to manufacture parts or blanks with complex shapes, especially those with complex internal cavities.

Since forging has the above characteristics, important parts subjected to impact or alternating stress (such as transmission spindle, ring gear, connecting rod, track wheel, etc.) should be processed by forging blanks, so forging processing in machinery manufacturing, mining, light industry Heavy industry and other industries have been widely used.

Automotive transmission system accessories sliding fork forgings

Automotive transmission system accessories sliding fork forgings

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.

Raw-material

Raw-material

The 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. The ratio of the cross-sectional area of ​​the metal before deformation to the cross-sectional area after deformation is called the forging ratio. Correct selection of forging ratio, reasonable heating temperature and holding time, reasonable initial forging temperature and final forging temperature, reasonable deformation and deformation speed have a great relationship to improve product quality and reduce cost.

Conventional small and medium forged materials 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 performance 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.

Forging materials in addition to the usual materials, such as various components of carbon steel and alloy steel, followed by aluminum, magnesium, copper, titanium and other alloys, iron-based superalloys, nickel-based superalloys, cobalt-based superalloys The deformed alloys are also finished by forging or rolling, except that the alloys are relatively narrow in plasticity, so the forging difficulty is relatively large, and the heating temperature, opening and forging temperature and final forging temperature of different materials have strict requirements.