The production process of titanium coil cold rolling is: hot rolled coil → hot rolled coil welding, lead belt linking → annealing → pickling → surface grinding → rolling → cleaning → vacuum annealing → leveling, straightening → finishing → packaging.
Before cold rolling, connecting the lead belts at both ends of the coil is an important measure to improve the finished product yield. After hot rolling, an oxide layer will form on the surface of the titanium coil, which needs to be removed by the "mechanical descaling + mixed acid pickling" process. Under normal circumstances, the production capacity of a single-stand rolling mill can meet the production requirements of titanium coil cold rolling. However, due to the significant anisotropy of titanium, titanium coil cold rolling usually uses a multi-roll mill with a smaller diameter working roll and is rolled under high tension conditions. The finished product annealing stage must adopt vacuum annealing to ensure the surface quality of the product. The purpose of leveling and straightening is to allow the finished titanium coil to obtain a suitable surface state and a good plate shape.
The specifications of hot rolled coils used in cold rolling are generally (3~6)mm×(600~1600)mm, and the weight of a single coil is less than 10t. The work in the raw material preparation stage mainly includes assembling small coils into large coils, welding lead strips, cutting and updating lead strips, cutting cracked edges, etc. Since titanium coils are generally rolled using a reversible rolling mill, the ends of the coils cannot be rolled normally, which will cause a large waste of titanium materials. Therefore, the guide strips must be connected at both ends of the coil before cold rolling to improve the yield rate of the finished product and reduce production costs.
When the material of the lead strip is pure titanium as the strip blank, it can be connected by butt welding; but when the material of the lead strip is not pure titanium (such as stainless steel, etc.), it cannot be directly welded, so it must be connected by mechanical riveting. After the cold rolling is completed, the lead strip needs to be removed and can be reused. In the raw material preparation stage, a coil assembly unit is required to assemble small hot-rolled coils into large coils, weld leader tapes to hot-rolled coils, cut off the original leader tapes of titanium coils after intermediate rolling, and weld appropriate new leader tapes. In addition, in order to reuse the leader tapes, a leader tape straightening unit is required to straighten the used leader tapes, cut the heads and tails, and manufacture new leader tapes.
