Deep drawing of cylindrical parts with formability of titanium rod and titanium alloy

The common deformation methods of titanium sheet can be summarized as deep drawing, stretching, flanging, bending and composite forming 5 kinds. However, it is difficult to make typical test pieces by using a single deep drawing deformation mode. So the test is actually used in the composite deformation mode. In addition, the test will inevitably bring the influence of the mold structure and operating process factors, so the evaluation of the drawing property of the plate is a lot of miscellaneous identification. Based on the limit drawing coefficient K(LDR) as the index, many evaluation methods have been proposed from analysis, experiment and statistics, and many problems have been solved. However, most of the commonly used steel and aluminum as the main object, so it must be amended and supplemented for titanium and titanium alloys.

The drawing test method of cylindrical parts was proposed by Swift in 1940, using step by step increase of wool to measure the limit drawing coefficient K value, and was recommended by the International deep drawing Research Association in 1967 as the international standard, this method has identified a large number of steel, aluminum and copper plate drawing performance.

When used for titanium, especially α and α+β titanium alloys, there are mainly the following problems:

a, bending and breaking at the four corners of the punch;

b, wrinkle at the rounded corner of the die.

This is caused by the poor bending and wrinkle resistance of titanium alloy, which cannot fully explain its deep drawing property. For example, Ti-6Al-4V and Ti-5Al-2.5Sn plates have poor or impossible depth drawing.

The Englhardt or maximum drawing force test method is used to determine their drawing properties, because the material is required to fully fit the punch and then the drawing force is determined, so the bending failure problem is more serious.

It is suggested to enlarge the punch corners, take anti-wrinkle measures at the die corners and use graphite lubricant for deep drawing test of titanium alloy.