What Is Hot Processing?

Hot working is a processing method that simultaneously produces plastic deformation and recrystallization of metal materials under conditions above the recrystallization temperature. Hot working usually includes casting, forging, welding, heat treatment and other processes. Hot working can change the structure of a metal part while forming or change the established state of a formed part to improve the mechanical properties of the part.

Hot working is to produce metal materials at the same time above the recrystallization temperature.

The method of smelting metal, manufacturing molds, and pouring molten metal into molds to obtain certain shapes and properties after solidification is called casting. Casting is an applied science and is widely used to produce machine parts or blanks. The liquid metal is gradually formed by cold-adding the solidified surface and has the following advantages:

(1) It can produce blanks with complex shapes, especially with complex inner cavity, such as various boxes, beds, frames, etc.

(2) Wide adaptability in casting production and great process flexibility. Metal materials commonly used in industry can be used for casting. The weight of the casting can be from several grams to several hundred tons, and the wall thickness can be from 0.5 mm to 1 meter.

(3) Most of the raw materials used for storage and manufacturing are from a wide range of sources, low prices, and direct use of waste machinery, so the cost of castings is low.

However, liquid forming also brings certain disadvantages to the part, such as defects such as cast structure, sulphur pine, coarse grains, easy to produce shrinkage, shrinkage, porosity and other defects. Therefore, the mechanical properties of the casting, especially the impact toughness, are lower than those of the forging of the same material. In addition, there are many casting processes and it is difficult to accurately control, which makes the quality of the castings not stable enough and the casting labor conditions are poor.

With the development of casting technology, in addition to the machine manufacturing industry, various castings are also widely used in various areas of the national economy such as public facilities, daily necessities, arts and crafts, and construction. The production process methods of castings are roughly divided into two categories: sand casting and special casting.

Welding is an important metal connection technology in modern manufacturing technology. The essence of the joint forming technology is: using the method of heating and heating and pressing at the same time to make the separated metal parts form an atomic bond, thereby forming a new metal structure.

The essence of welding is to make two separate objects through heating or pressure, or use them together. With or without filler materials, the process of forming a whole by virtue of the connection between atoms or molecules and the diffusion of particles. To make two separate objects form a permanent combination, first, the two objects must be brought close to each other to a distance of 0.3 to 0.5 nanometers, so that the force between the atoms can interact with each other, which is easy for liquids. However, a large amount of external energy is required for solids to reach the distance between atoms in contact between the contact surfaces. However, due to the high solid hardness of the actual metal, no matter how high the surface accuracy is, it can only be part of the point of contact. In addition, there are various impurities on the surface, such as oxides, grease, dust and gas molecules. These are the factors that prevent the atomic bonding of two objects. The welding technology is to use heating, pressure or a combination of the two methods to overcome the factors that hinder the atomic bonding to achieve the purpose of long-term, semi-solid connection between the two. .

Advantages of welding: The mechanical properties and use performance of the joint are good. Compared with riveting, the metal structure manufactured by the welding process is lighter in weight, saves raw materials, has shorter manufacturing cycle and lower cost.

Welding problems: the structure and properties of the welded joints will change compared to the base metal; defects such as welding cracks are prone to occur; residual stress and deformation will occur after welding. These will affect the quality of the welded structure.

According to the characteristics of the welding process, welding types are mainly fusion welding, pressure welding, and brazing.

Under the action of impact force or static pressure, hot or ingots are locally or totally plastically deformed to obtain a desired shape, size, and performance. The processing method is called forging.

Forging is generally performed after heating rolled steel, square steel (medium and small forgings) or steel ingots (large forgings) to a high temperature. Forging can improve the as-cast structure, casting defects (shrinkage, pores, etc.), make the segment structure compact, grain refinement, and uniform composition, thereby significantly improving the mechanical properties of the metal. Therefore, it is mainly used for important mechanical parts or blanks that are subject to heavy loads, shock loads, and alternating loads, such as the spindles and gears of various machine tools, crankshafts and connecting rods of automobile engines, crane hooks and various tools and molds. Wait.

Forging is divided into free forging, model making and tire mold.

Punching is a processing method to obtain a product by separating or deforming a metal or non-metal sheet with a die on a punch. Sheet metal stamping is usually performed at room temperature, so it is also called cold stamping. The material used for stamping must have good plasticity. Commonly used are low carbon steel, high plastic alloy steel, aluminum and aluminum alloy, copper and copper alloy and other metal materials. And leather, plastic, bakelite and other non-metal materials. The advantages of stamping are high productivity and low cost; the finished product has complex shapes, high dimensional accuracy, good surface quality and rigidity, high strength and light weight, and can be used without cutting. Therefore, it is widely used in the production of automobiles, tractors, motors, electrical appliances, daily necessities and defense industry.

Basic process of hot working stamping

The basic processes of stamping mainly include punching and blanking, bending, and deep drawing. The process of separating the slab along the closed contour under the action of the die edge is called punching or blanking. Bending is the process of bending the workpiece axis to a certain angle and curvature by using a bending die. Deep drawing is the process of using a mold to convert a flat plate blank into a hollow shape such as a cup shape or a box shape.

Hot working die

The die is an indispensable process equipment to realize the separation or deformation of the blank.

The main components and functions of the punching die: The working part includes the punching die and the concave die, etc., to achieve the separation or deformation of the sheet, and complete the stamping process. The positioning part includes a guide plate, a positioning pin, and the like, for controlling the feeding direction and the feeding distance of the blank. The discharging part includes a discharging plate, a top plate, and the like, and is used for unloading a slab or a workpiece after punching. The guide part includes a guide post, a guide sleeve, etc., which are used to ensure that the upper and lower molds are accurately closed. The phantom part includes upper and lower mold plates, die handles, etc., which are used to connect with the punch and transfer pressure.

Types of punching dies: punching dies, blanking dies, bending dies, deep drawing dies, etc. can be divided according to the process properties of the die dies, and they can be divided into simple dies, continuous dies, and compound dies according to the degree of combination of the processes.