Why do aluminum coils have curling problems after cooling at high temperatures?

　　In the process of making aluminum coil, in order to help change its shape, we need to heat it at high temperatures, in the high temperature state it will be softer, and its shape is more likely to some changes in the shape of the shape adjustment, it can be lowered down the temperature, so that it maintains a certain degree of hardness, but there are some cases in the high-temperature cooling is completed, the aluminum coil will appear some curling problems, and the aluminum coil will not be able to change its shape. What is the reason for this?

　　Cooling will appear bending phenomenon, the reason is: general air-cooled conditions, all parts of the aluminum coil and air contact heat transfer coefficient are flat, but because the wall thickness or shape is not the same, the parts of the heat dissipation rate is not balanced, resulting in a thick-walled or hollow tube heat dissipation rate than the thin-walled part of the slow, resulting in it in the cooling will appear to the hollow part or thicker wall parts of the phenomenon of bending.

　　Bending reasons and processes are as follows:

　　1, the thin-walled part of the temperature drop quickly, the first contraction force, thick-walled part or hollow tube part of the temperature drop slowly, almost no contraction force;

　　2, thin-walled part of the cross-sectional area is small, resulting in a smaller contraction force, or by the traction machine traction eliminated;

　　3, leaving the traction machine, the temperature continues to fall;

　　4, thick-walled part or hollow tube part of the cross-sectional area is larger, with the temperature drop gradually produce a larger contraction force, thin-walled part of the temperature has dropped significantly, no longer produce contraction force or contraction force is smaller;

　　5, aluminum coil cross-section by the size of the contraction force is not uniform, along the extrusion direction to the thick-walled part or hollow tube part of the bending.

　　The above is about the aluminum coil in high temperature cooling will appear curling problem of the method of introduction, I hope it can help you.