Head forming can be divided into stamping and spinning. According to whether it is heated or not, it can be divided into cold forming and hot forming. Compared with the traditional hot stamping technology, the hot spinning technology of the head has many advantages. It does not need to invest in expensive die costs. For the non-standard shape, the non-standard size of the head will not be limited. The cost of making the head is relatively low. The spinning process can be flexible and changeable, and the material with cracking tendency can be grasped. Larger. In addition, the size accuracy of spinning forming head is also higher.
1. The principle of hot spinning process is as follows:
The temperature of metal material is inversely proportional to its strength, and its strength decreases with the increase of temperature. When the temperature is below 600 C, the effect of temperature change on strength is not great. When the temperature reaches 700 C, the strength of the material will decrease by about 2/3, while when the temperature reaches 900 C, its strength is only about 1/10 of that at room temperature. Hot spinning is the use of this principle to achieve the formation of the head, using a heating device to spin the part of the head needed to be heated locally, when a certain temperature is reached, the spinning begins, in the spinning process, continue to heat the part of the head needed to be deformed, until the head spinning forming.
2. Hot spinning process:
1) The heating process of hot spinning is completely opposite to that of hot stamping. Hot stamping is the process of heating in the furnace to over 900 C and then moving to the stamping machine. The temperature of hot stamping is a process of constant cooling. Normal specifications require that the final pressure temperature must be higher than 680 C. It is difficult to grasp and determine the specific reasons in the specific operation process. The internal temperature is high and the superficial temperature is low, so there are often some over-standard conditions. Hot spinning is to spin after reaching the initial spinning temperature, while continuing to heat the head, so the temperature of the head is rising slowly, which can ensure that the final spinning temperature reaches the specified value or above.
2) Specific hot spinning process: after the head (drum or preloading) which needs to be flanged is installed on the press, the head is rotated and heated by a heating gun. When the heating temperature is higher than 650 C, the spinning can be carried out. The flanging of the head is completed by continuous rotating extrusion of the internal and external dies, and the flanging of the head is completed by installing the heating gun. Feedback distance of ruler or digital encoder mounted on mobile body determines whether the diameter of the head is machined in place (the shrinkage size of the head after cooling needs to be reserved), and closes the heating gun after the spinning of the head is completed. The final spinning temperature of the head can reach more than 850 C.