The Mechanism Analysis Of Ridge Buckles On Cold-rolled Pure Titanium Sheet

After cold rolling, the surface of the circumferential coil generates a local bulge in the coiling process, so called the ridge buckles. There were many discussions and results about the causes of the ridge buckles, but it hadn’t got the final answers yet. At present, the research of the ridge buckles of the cold-rolled titanium was still in a beginning stage. Therefore, it was necessary to get in-depth analysis for the causes of the ridge buckles on the pure cold-rolled titanium sheet. The paper began with the process of the raw material of the hot rolling, the cold rolling, field trial production, mechanism analysis and emulating calculation and so on, and then analyzed the reasons generated the ridge buckles. The paper studied the possible measures of weakening the ribbing degree and improving the ridge buckles effect for mitigating or eliminating the ridge buckles on the following process. The main research and results were displayed as follows:(1) After analyzing the raw material of the hot rolling, it was found that the ridge buckles was related to the local uneven thickness of the strip after the hot rolling and the shape controlling, etc. That was to say,the local uneven thickness of the strip after the hot rolling, the shape controlling had a certain relationship with the ridge buckles.(2) According to the site equipment, rolling process was analyzed. Under good conditions of devices, it was found that rolled titanium band ridge buckles generation of defects in the process through on-site trial production had main relationship with tension systems primarily institutional settings and shape setting and controlling of the curve and it was insensitive to the reduction. The ridge buckles can be suppressed by properly reducing the winding tension, but it would produce bad roll defects by too small winding tension.(3) A wide and thin strip rolling model was established by a nonlinear element software to study the reason for the formation of defects, the local extension and other changes after rolling was simulated, which showed that high tension rolling system would easily produce edge waves, local waves defects, thereby increase the probability of the ridge buckles. Therefore, certain decrease of tension would reduce the probability of defects.For pure titanium material properties, raw materials characteristics, cold rolling process system and so on, a critical condition mathematical model of the ridge buckles was established to analyze the generation mechanism of the ridge buckles, which provided a theoretical basis and guidance to reduce the defects. Combined with the model and the request of preventing rolling rotten, it proposed that the appropriate pre-tension ranges from0.27σs to0.35σs for0.6mm cold-rolled titanium strip, and by trial rolling, it effectively inhibits the generation of the defects of ridge buckles which proved the validity of the model.(5) Several suggestions were proposed to optimize the cold-rolled pure titanium sheet shape by the in-depth analysis of raw materials and the production process.