1. Punching and shearing dies: the work is completed by shearing. The commonly used forms are shearing and punching dies, blanking and punching dies, punching dies, trimming and punching dies, flanging and punching dies, drawing and punching dies and punching dies.
2. Bending die: it is to bend the flat hair into an angle shape, depending on the shape of the parts, precision and production, but there are many different forms of die, such as ordinary bending die, cam bending die, flanging die, arc bending die, bending and punching die and twisting die.
3. draw the mold: mold is made of flat hair embryo into a seamless container.
4. Forming die: refers to the use of various local deformation methods to change the shape of the hair embryo, the form of a convex forming punch, flange forming punch, neck forming punch, hole flange forming punch, flange forming punch.
5. Compression Die: It is the use of strong pressure, so that the metal hair flow deformation, become the desired shape, the types of extrusion die, embossing die, stamping die, end stamping die.
Due to the different production processes, the production costs of the two types of steel plants are quite different, and the appearance quality and internal quality of the products are also quite different.
Different smelting processes
Large-scale burden smelting process is electric furnace smelting + refining + vacuum degassing. The chemical composition of the process steel is precisely controlled, the gas content in the steel is low, and the purity of the steel is high. In general, the small factory charge is to mix scrap and burden in medium frequency furnace and pour flat ingot directly. This process has large deviation in chemical composition, more impurities in steel, higher gas content, resulting in more shrinkage and internal cracks of finished products, which seriously affects the processing performance of steel.
Rolling process is different.
The ingot of large mill is forged and billet is rolled again, and it is continuous rolling with multiple deformation of multi-mill in the rolling process. The small mill stock is the ingot rolled directly back and forth by a single rolling mill. The ingot has small deformation, small rolling ratio, inhomogeneous microstructure and large non-metallic inclusion particles. The direct expression is that the material is sawing and drilling.
Different appearance quality
Because the large mill stock is continuously rolled, and the number of deformation is more, its appearance size accuracy is higher, both sides of the approximate right angle. Due to the fact that the production process of small factory materials is entirely controlled manually, the size deviation is large, the tolerance of thickness and width is large, the round angle of flat steel is large, and the section deviates from rectangle.
Different ways of heat treatment for finished products
Complete spheroidizing annealing process is adopted to ensure that the grade of carbide in the steel is not less than 4 and the hardness uniformity is guaranteed. The common softening annealing process and even natural cooling are adopted for small-scale materials, which can not guarantee the uniformity of carbide grade and hardness in steel.
The difference in the production process directly affects the use of materials. Firstly, the size deviation of small factory materials is large, the flatness is poor, resulting in a large enough machining allowance in processing, otherwise the processing can not come out. Secondly, due to the uneven hardness of small factory materials, it is difficult to drill holes, low processing efficiency, workpiece deformation after processing, and even die scrap.
Thirdly, the impurity content of small factory materials is higher, the gas content in steel is higher, and the distribution of carbide is very uneven, which results in serious deformation of the mold during heat treatment, or even heat treatment cracking, which makes the mold scrap.