However, when forming the GA DP600 without prephosphate coating, necking was not able to be detected and the shear fracture (typical fracture around the tight die radius without necking for AHSS, Shih et al.
In this forming condition, the material at the top of the punch was not able to flow uniformly over the die radius to the side wall, where the shear fracture occurred.
Many studies had been conducted and there are few parameters found to have effect on springback such as holding force and die radius
(Ouksi et al.
and its solution is the function of secondary coating die radius
at this time.
Bending and unbending over the die radius
is also provided by this tensile stress on the cup wall.
Influence factors Factors Levels of variations 1st 2nd 3rd level level level Punch radius Rp[mm] 54 55 56 Die radius
Rf[mm] 5 6 7 Blankholder force BHF[kN] 30 50 70 Clearance between 1 1.
where R and L are the die radius
and die length, [DELTA]P is the driving pressure, and q is the volumetric flow rate.
The accuracy of the velocity measurement verified by integrating the radial melt velocity for any given die radius
to give the output rate, this being calculated to be approximately 91%.
Three parameters were taken into account in this design of experiment: blankholder force (A), punch radius (B) and die radius
r]) for any given die radius
(r) as expressed in Eq 3, to give the output rate (Q).
We will decrease the outer die radius
to lower the DRB.
5 R, R being the die radius
, and the finite element meshes used are shown in Figs.