Development technique for deep drawing without blank holder to produce circular cup of brass alloy

Abstract

In this paper a new mechanism for deep drawing was proposed to produce circular cup from thin plate without blank holder. In this technique the die assembly includes punch, die and die-punch. A 2D axisymmetric finite element model was built using DEFORM software. Effect of die geometry (half-cone angle) on maximum load, thickness distribution, strain distribution and effect of clearance ratio between punch and (die-punch) on the wrinkling of the cup were investigated. Three half-cone angles of die (15o, 30o and 45o) were used for forming sheet metal of brass (CuZn37) which had initial thickness of (1mm) at four clearance ratio (c/t) for die of 30o half-cone angle. Finite element model results showed good agreement with experimental results. Die of 30o half-cone angle with clearance ratio (c/t) of 0.9 gave the best product without wrinkling. The main advantage of this technique compared to the conventional deep drawing is that the circular cup can be carried out in single action press with limit drawing ratio (LDR) of 1.86 and blank diameter to blank thickness ratio (d/t) < 86.

12 mm Thick Circular Blanks of Al-killed AISI 1020 Steel -Applied for Cylindrical Cup Manufacturing by Multistage Deep Drawing with Simultaneous Ironing

“…A series of cup drawing experiments were conducted by multistage (three stages) deep drawing with simultaneous ironing process on high speed mechanical press machines, without using blankholder considering relatively thicker blanks 5 . The sequence of processing steps those were followed in the experimental work such as: blanking of strips to obtain circular flat blanks -facing of blanks at both sides -stress relief annealing, surface treatment and lubrication -stamping of blanks to obtain a preformed shape-stress relief annealing, surface treatment and lubrication -first stage of cup drawing -stress relief annealing, surface treatment and lubrication -second stage of cup drawing -stress relief annealing, surface treatment and lubrication -third stage of cup drawing -stress relief annealing.…”

“…In order to maintain the relative thickness, it needs to cut a blank of larger diameter that associated with processing difficulties like, needs of larger die -punches, increased draw forces demands a greater press stroke, requires more numbers of draw steps to accommodate draw ratio and arousal of various forming defects etc. On contrary, increase in blank thickness raises the level of formability limit diagram (FLD) [1][2][3] , enhances limit draw ratio (LDR) value 2,4 , reduces tendency of wrinkling 2,5 and earing effects on cups 6 , which can be advantageously manoeuvred for manufacturing of long cylindrical cups. According to Saleh and Ali 5 and Suchy…”

“…Sometimes wall ironing is purposefully accompanied with deep drawing for achieving cups with greater height-to-diameter ratio, reduced uniform wall thickness [8][9][10][11] and optimisation in process time 12 .According to Saleh and Ali 5 , drawing with ironing also helps in increasing the LDR value. Moreover, the metal forming due to ironing is not affected by normal plastic anisotropy (r m ) value, rather it reduces earring effect 1 .…”

Cylindrical Cup Manufacturing Using 12 mm Thick Circular Blanks of AISI 1040 Graded Medium Carbon Steel: an Innovative Approach

“…Larger blank diameter is associated with various processing difficulties like, needs of larger die-punch geometry, greater press stroke due to increased draw forces, extra draw steps to be adapted and also makes arousal of forming defects in drawn parts. On contrary, increase in blank thickness raises formability limit, 1,2) enhances drawability ratio, 3) reduces wrinkling 4) and earing tendencies of cups. 5) Also, thicker blanks with relative thickness, > 2%, are preferably drawn without blank-holder, because of thickness prevents the blank from collapsing under tangential pressure.…”

“…5) Also, thicker blanks with relative thickness, > 2%, are preferably drawn without blank-holder, because of thickness prevents the blank from collapsing under tangential pressure. 4,6) Steel cups are mostly used in automobile, can making, defence industries and other engineering applications. These cups are manufactured by deep drawing method which needs to maximize the mean normal anisotropy (r m ) and minimize the planar anisotropy (Δr) values of the material.…”