At the beginning of the production of Jiangmen ceiling fans, after chemical milling and rolling leveling, occasional severe bulging and warping deformation may occur in the chemical milling area. After using the craft hammering method for correction, there are many hammer marks on the surface of the parts that have been hammered, which does not meet the skill requirements and affects the quality of Jiangmen ceiling fans. Moreover, the craft hammering leveling requires high skill levels for sheet metal workers, resulting in high labor volume and intensity. For a long time, the problem of aluminum plate milling for fan blades has become a skill point for Jiangmen ceiling fan manufacturers.

To address the issue of milling aluminum plates for fan blades, we can conduct pre tensile processing tests on the aluminum plates according to process requirements.

The rolled Jiangmen ceiling fan aluminum plate has residual internal stress. During the rolling process, due to the inconsistency between the surface temperature and the center temperature, the surface temperature is lower than the center temperature, and the surface is hindered by the friction force of the rolling rolls, resulting in residual internal stress in the plate after the rolling process is completed. After the heat treatment process is completed, the outer surface of the plate cools faster than the center, and the outer surface cools and shortens first. The outer surface experiences compressive stress against the center, and the center resists the shortening of the outer surface, while tensile stress occurs on the outer surface. Therefore, rolled and quenched plates, after removing a part of the material through mechanical processing or chemical milling, disrupt the original internal stress balance of the plate and cause deformation. The way to address this issue is to pre stretch the aluminum plate.

The so-called pre stretched plate refers to applying a single directional external force to the two ends of the quenched plate for tension, causing a small amount of plastic deformation of the plate, in order to eliminate or reduce the original residual stress of the plate and make it tend towards uniformity.

During the stretching process of fan blade aluminum plate, the stress and strain at each point on the plate are changed based on the stress-strain curve of tensile deformation. When the stress is less than the yield limit, the relationship between stress and strain is linear. When the stress exceeds a fixed value, the relationship between stress and strain no longer changes linearly, and the stress increment decreases with the addition of strain. Therefore, under the effect of tensile force, a portion of the original residual stress of the sheet enters the yielding zone first. With the addition of strain, it promotes the gradual homogenization of internal stress (tensile stress) distribution at various points inside the sheet, and tensile deformation continues to be added. Points with residual stress in the sheet become tensile stress. When they are all greater than a fixed value, the tensile stress distribution of the board is basically uniform. When the external load is removed, the remaining stress of the quenched plate can be effectively eliminated after the elasticity of the plate is shortened.

From the above analysis, it can be seen that the reason for the deformation of Jiangmen ceiling fan blades during the manufacturing process is that there is residual stress in the quenched plate. After chemical milling, the original stress balance of the plate is disrupted, causing deformation of the aluminum plate. Secondly, during roll bending calibration, the remaining stress in the sheet metal can cause warping deformation of the parts. Therefore, the deeper the chemical milling, the more severe the tortuous deformation after chemical milling.

Therefore, from the analysis of the characteristics of pre tensioned plates, it can be seen that using pre tensioned plates is one of the effective ways to eliminate the stress deformation of the Jiangmen ceiling fan blade aluminum plate.

Article source: Jiangmen ceiling fan www.gd-dx.cn