Metal drawing technology refers to a mechanical processing technology that uses a mold to press a certain shape plate blank after blanking into a variety of open hollow parts or to reduce the diameter of the open hollow blank and increase the height of the blank. The deep drawing process can be used to make cylindrical, stepped, tapered, spherical, box shaped and other irregular shaped thin-walled parts. It can also make parts with extremely complicated shape, such as flanging, bulging, flaring and necking. The following is a brief introduction of the factors affecting the tensile properties of metal materials.
1. Properties of metal raw materials
Metal materials are usually referred to as metal elements or metal elements, which have metal properties, including pure metals, special metals, alloys, and metal intermetallic compounds. In the process of metal material processing, its microstructure will be affected and changed accordingly. The special properties of metallic materials are mainly manifested in the following aspects:
(1) fatigue. Many metal materials, such as engineering components, mechanical parts and so on, need to bear the alternating load during the working process. Under this effect, although the yield limit of metal materials is far higher than the stress level, the phenomenon of sudden brittle fracture will occur after a long period of stress circulation. This phenomenon is the metal material. Fatigue is the most common and dangerous form of fracture.
(2) plasticity. Under the action of external force of load, the ability of permanent deformation of metal materials without damage is the plasticity of metallic materials. The better the plasticity of metal material, the more plastic deformation can be formed in a larger range, and the strength of metal material is strengthened in the process of plastic deformation, and the safety of metal material is increased.
(3) hardness. Hardness mainly refers to the resistance of metallic materials to hard objects pressing into their surfaces. It is one of the important indicators to consider the properties of metallic materials. The hardness of metal material is the result of the joint action of the initial plastic deformation resistance and the continuous plastic deformation resistance. Generally, the higher the hardness of the metal material is, the better the wear resistance will be.
Two. The effect of processing on the tensile properties of metal materials
The tensile properties of metal workpiece will have different effects according to the order of deformation, processing speed, stamping oil performance, processing temperature and so on. The selection of reasonable process according to the requirements of different workpiece performance can significantly improve the tensile properties of the workpiece.
(1) effect of processing temperature on tensile properties of metallic materials
With the increase of the molding temperature, the molecular motion energy, the free volume of the melt and the activity of the segment will increase, which reduces the intermolecular interaction and the melt viscosity, and increases the transverse tensile strength of the metal materials. However, this does not mean that the higher the molding temperature is, the transverse tensile strength of the metal materials will increase first and then tend to be gentle with the prolongation of the processing time.
(2) effect of drawing speed on tensile properties of metallic materials
In the internal metal materials, there are often dislocation and other crystal defects. At normal temperature, the tensile properties of metal materials are mainly in the stage of elastic deformation and plastic deformation. The plastic deformation of metal materials mainly depends on the dislocation mode. Once the external force exceeds the critical value of the slip, it will lead to the movement of the crystal direction and the crystal surface, and the corresponding motion speed will be produced during the movement, which causes the tensile strength of the metal material to increase with the tensile speed during the stretching process. Rise。
(3) impact of stamping oil on tensile properties of metallic materials
The temperature of the general workpiece in the stamping process will rise quickly, and the special stamping oil must be used to cool the workpiece. Otherwise the temperature will cause the problem of the workpiece to be blackened by the decrease of the surface finish of the metal. Besides the smoothness of the workpiece, the life of the die will be shortened and the accuracy will be reduced. The special stamping oil will stick to the key parts of the heat automatically and protect the mold from wear. Moreover, the workpiece will not oxidize rusty for a short time under the protection of oil products, and will not affect subsequent electroplating and welding processes.
To sum up, in the process of metal material processing, various factors will have a certain effect on the tensile properties of metal materials, and make the tensile strength, the elongation at the end and the surface quality of the workpiece change. Reasonable arrangement of technology helps enterprises to reduce costs and enhance product competitiveness. By using the self developed vulcanized lard and sulphide fatty acid ester as the main additive, it has a good performance of extreme pressure and abrasion resistance. It can effectively improve the surface finish and processing efficiency of the workpiece, and have no harm to the human body, the workpiece, the equipment and the environment. It is the reference of many metal processing enterprises in China. The partners have been well received by customers at home and abroad in practical applications.
