Technological introduction
The comprehensive mechanical properties of blank are improved remarkably. In addition, the surface finish of the blank produced by this process reaches grade 7 (Ra1.6), just like the surface produced by cold extrusion process or machine, with metallic luster. Therefore, we will die casting die forging process called "limit forming process", than "no cutting, less spare forming process" further. Die-casting die forging process also has an advantage that in addition to the production of traditional casting materials, it can also be used to produce deformed alloys, forging alloys, the production of very complex structure of parts. These alloy grades include: hard aluminum superhard aluminum alloy, forged aluminum alloy, such as LY11, LY12, 6061, 6063, LYC, LD, etc.). The tensile strength of these materials is nearly twice higher than that of ordinary cast alloys, which is of more positive significance for parts such as aluminum alloy automobile wheels and frames that want to be produced with higher strength impact resistant materials.
Introduction of die casting
Pressure casting, referred to as die casting, is a casting method in which molten alloy liquid is poured into the pressure chamber, the cavity of the steel mold is filled at high speed, and the alloy liquid is solidified under pressure to form a casting. Die casting is distinguished from other casting methods by high pressure and high speed. ① The liquid metal is filled with the cavity under pressure, and crystallizes and solidifies at higher pressure, the common pressure is 15-100mpa. ② Liquid metal filling cavity at high speed, usually in 10~50 m/s, some can be more than 80 m/s, (through the gate into the cavity linear velocity - gate speed), so the filling time of liquid metal is very short, about 0.01~0.2 seconds (depending on the size of the casting and different) can be filled cavity. Die casting machine, die casting alloy and die casting die are the three main elements of die casting production. The so-called die casting process is the organic comprehensive use of these three elements, so that the appearance, internal quality, good size in line with the drawing or agreement requirements of qualified castings, and even high quality castings can be produced steadily and rhythmically.
- Die casting machine: the heating conditions of the press chamber of the die casting machine can be divided into two categories: hot chamber and cold chamber. And the different placement of the press chamber and the die, cold chamber die casting machine can be divided into vertical, horizontal and vertical three forms of die casting machine.
- Die casting alloy: the alloy used in die casting is mainly non-ferrous alloy, as for ferrous metals (steel, iron, etc.) due to die materials and other problems, less used. In the non-ferrous alloy die casting, aluminum alloy is widely used, followed by zinc alloy. Note: ① The casting temperature is generally measured by the temperature of the metal liquid in the holding furnace. ② The casting temperature of zinc alloy should not exceed 450℃ to avoid coarse grain
Mould element
Die casting mould is one of the three main factors of die casting production. The mould with correct and reasonable structure is the prerequisite for the smooth progress of die casting production, and plays an important role in ensuring the casting quality (pass rate).
Process characteristics
Due to the characteristics of die casting, the correct selection of process parameters is the decisive factor to obtain high quality castings, and the mould is the premise to correctly select and adjust the process parameters. The mould design is essentially a comprehensive reflection of the various factors that may occur in die casting production. If the mold design is reasonable, there will be fewer problems encountered in the actual production, and the qualified rate of casting is high. On the other hand, the mold design is not reasonable. In example 1, the wrapping force of the moving fixed mold is basically the same in the casting design, while the pouring system is mostly produced in the fixed mold, and it is put on the irrigation die casting machine which can not feed the punch after injection, so the casting cannot be produced normally, and the casting is always stuck to the fixed mold.
Although the finish of the mold cavity is very smooth, because the cavity is deep, it still appears to stick to the mold. So in the mold design, it must be comprehensive analysis of the structure of castings, familiar with the operation process of die casting machine, to know the possibility of die casting machine and the process parameters to adjust, master packing characteristics under different circumstances, and considering the mould processing methods, drilling, and fixed form, to design a practical, meet the production requirements of mold. At the beginning, it has been said that the filling time of liquid metal is very short, the specific pressure and flow rate of liquid metal is very high, which is extremely bad working conditions for die casting die, coupled with the impact of alternating stress of cold shock heat, have a great impact on the service life of the die. The service life of the mold usually refers to the number of die casting molds (including the number of waste products in die casting production) by careful design and manufacturing, natural damage under normal use conditions, combined with good maintenance and maintenance, before it can no longer be repaired and scrapped.
