Experimental Study Of Influence Of Tool Surface Parameter On Galling Defect

Galling is a very familiar defection in the process of forming of automobile panels, the manufacturing techniques demand very high surface quality because any light galling will influence the appearance of the lacquer layers, even reduce the panel's anti-causticity and shorten its life. Tool is the key factor affecting galling. through studying the law of the factors such as tool hardness,roughness. It would greatly improve the tool's life and anti-galling ability, and decrease the rejection ratio and production cost .It is very important for the automobile industry.This paper aim at solving galling in the stamping of auto panels. Through experiment and measurement analysis method, obtained the evaluating parameter and threshold for galling. Then, studied the influential law of the deformation mode and tool surface parameters on galling. Supplied a theoretical direction for manufacturing spot and die design. At same time made a solid base for further study of the hardness matching, influence of tool material and panel material on galling.The major contribution and innovative work are summarized as follows:Firstly, tool factors were precisely manufactured and the structure of special die was designed. This paper made a simple introduction to the device for studying galling in laboratory. Following the design requirement of experimental factors, realized the precise die hardness and die roughness by controlling the manufacturing process. To validate the result of fundamental experiments, designed the die structure based on the already existed special part's plane, made the drawing of all parts, finished the manufacturing , and passed the stamping try-out. Secondly, this paper obtained satisfactory evaluating parameter and the threshold for galling. To satisfy the requirement of evaluating galling in laboratory and manufacturing spot, by comparing the evaluating parameter using categorizing method, obtained a perfect, precise evaluating parameter for galling. Using this parameter, following the check process, got the threshold of galling. It can be used as quantitative parameter which decides if a galling part is qualified or not.Thirdly, this paper obtained the influential law of deformation mode on galling. Based on the experimental data, compared the galling performance under several different deformation mode. Then obtained that in the process of high strength steel stamping, as the increase of stamping times, the galling on stamping part's surface become severe. To box part and U part ,when forming at the same position of die, they got same galling performance.Finally, this paper obtained the influential law of tool parameter on galling. During the stamping process, as the increase of die hardness, part'surface occurs galling with more difficult. The die corner has great influence on galling occurrence. And with bigger die hardness, the burl is more difficult to occur. The die with bigger surface roughness is more difficult to occur galling. The coating on die can exert its effect against galling only in the condition that the die has high base hardness. At last, based on the law we got, made several suggestion to manufacturing spot and die design.