The common deformation methods of titanium sheets can b […]
The common deformation methods of titanium sheets can be summarized into five types: deep drawing, pulsation, flanging, bending and composite forming. However, it is difficult to make a typical test piece if a single drawing deformation method is used. Therefore, the compound deformation method is actually used in the test. In addition, the test will inevitably bring about the influence of mold structure and operating process factors, so the evaluation of sheet drawability is a lot of complicated knowledge. Guozhu’s research work mainly takes the limit drawing coefficient K (LDR) as an indicator, and proposes many evaluation methods from a variety of perspectives such as analysis, testing, and statistics, and solves many problems. However, commonly used steel and aluminum are the main objects, so they must be modified and supplemented for use in titanium and titanium alloys.
The drawing test method of cylindrical parts was proposed by Swift in 1940. It used the stepwise increase of wool to measure the limit drawing coefficient K value, and was recommended as an international standard by the International Deep Drawing Research Association in 1967. The drawing performance of steel, aluminum and copper sheets.
When used in titanium, especially α and α+β titanium alloys, there are mainly the following problems:
A. Bending and cracking occurred at the four corners of the punch;
B. Wrinkles and cracks are generated at the corners of the die.
This is caused by the poor bending and wrinkle resistance of the titanium alloy, and it cannot fully explain its drawability. For example, TC4 and TA7 boards have poor drawing properties or impossible to draw.
Use Englhardt or the maximum drawing force test method to measure their drawability, because the material is required to be completely close to the punch and then the drawing force is measured, so the problem of bending failure is more serious.
It is recommended to increase the fillet of the punch, take anti-wrinkle measures at the fillet of the die, and use graphite-containing lubricants for the deep drawing test of titanium alloy.