Die Corner Radius Research Articles

The effects of using coated tools in the deep drawing of aluminium

The performance of titanium nitride coated punches and dies in deep drawing is compared with that of uncoated tools, in terms of two parameters: the maximum punch force, and the limiting draw ratio. The effectiveness of titanium nitride coatings on tools with different corner radii is studied also. Deep-drawing experiments were conducted on aluminium using all possible combinations from two similar sets of tools: one uncoated, the other coated with titanium nitride. Both sets consisted of punches and dies with different corner radii. It was found that the titanium nitride coated dies reduced the maximum punch forces by 7.45 to 13.40%. The coated dies also improved the limiting draw ratios by about 4.59%, with the combination of uncoated punch and coated die yielding the largest limiting draw ratios. The punch forces were also reduced when the punch and die corner radii increased. The limiting draw ratios were improved with the increase of die corner radius, while punches of profile radii 6 to 7 times the blank thickness gave the highest limiting draw ratios. The experimental results agreed reasonably well with the theoretical predictions obtained by an approximate solution proposed by Duncan and Johnson.

The effects of using coated tools in the deep drawing of aluminium

The performance of titanium nitride coated punches and dies in deep drawing is compared with that of uncoated tools, in terms of two parameters: the maximum punch force, and the limiting draw ratio. The effectiveness of titanium nitride coatings on tools with different corner radii is studied also. Deep-drawing experiments were conducted on aluminium using all possible combinations from two similar sets of tools: one uncoated, the other coated with titanium nitride. Both sets consisted of punches and dies with different corner radii. It was found that the titanium nitride coated dies reduced the maximum punch forces by 7.45 to 13.40%. The coated dies also improved the limiting draw ratios by about 4.59%, with the combination of uncoated punch and coated die yielding the largest limiting draw ratios. The punch forces were also reduced when the punch and die corner radii increased. The limiting draw ratios were improved with the increase of die corner radius, while punches of profile radii 6 to 7 times the blank thickness gave the highest limiting draw ratios. The experimental results agreed reasonably well with the theoretical predictions obtained by an approximate solution proposed by Duncan and Johnson.

Analysis of bending effects in sheet forming operations

AbstractThe majority of work in numerical analyses of sheet metal forming operations is based on the simple membrane‐shell theory which neglects the effect of sheet bending. While useful information can be extracted from these analyses, especially for stretch‐dominated operations, the membrane theory is basically inadequate for analysing the draw‐type operations where sheet metal bends, slides and unbends over a draw radius.This paper presents axisymmetric and plane‐strain finite element analyses of stretch/draw of sheet metal over a die corner radius. Numerical solutions obtained from a total Lagrangian formulation of a finite‐strain thin shell theory are used to indicate the relative significance of including the bending effects in various simple forming operations. Comparisons of the calculated results with available experimental data are also given.

Influence of die variables on cavity press forging loads

SUMMARY Slug, die and process parameters largely determine the load requirements when forging any given part. An earlier report (Balogun 1974) has indicated the effects of flash dimensions on deformation forces during cavity press forging of round mild steel slugs. The current paper discusses the influences of three main die variables—die friction, extrusion ratio and flash land shape on press forging loads. The effects of die corner radii, draft angles and die complexity are also briefly mentioned to give a balanced outlook.