Nghiên cứu khoa học công nghệ
EFFECT OF LUBRICANTS ON WALL THICKNESS IN THE
DEEP DRAWING PROCESS
Nguyen Truong An, Nguyen Manh Tien*
Abstract: In the paper, results of effect of lubricants on wall
thickness in the deep
drawing process are researched. The results are verified by the simulation and
experimental. The research results order to reduce the minimum thickness of sheet
metal in the deep drawing, selection of reasonable lubricants, contribute to improve
product quality and meet the requirements of the working conditions of the product.
Keywords: Deep drawing process, Thickness, Lubricants, Simulation, Experimental.
1. INTRODUCTION
Deep
drawing
is
one
of
the
most
common
processes
metal
sheet
deformation.
Deep
drawing
is
the
transformation
of
a
plat
blank
in
to
a
cylindrical,
parallelepiped
or
complex
shape
(Fig
1).
The
process
of
deep
drawing
is
characterized
by
a
very
complicated
strain,
affected
by
the
following
parameters
[1]:
drawing
ratio,
blank
holder
presure,
radius
of
die,
coefficient of friction, speed of the punch,
material properties… The quality of deep
drawing parts is influenced by certain
Figure 1. The first of deep drawing
process [1](1. Die; 2. Punch;
variables that can be controlled [1, 8, 9].
3. Blank holder).
In the deep drawing process happens the thickness of sheet material in the
drives deformation [1,5]. At different the placements, the thickness has different
values. The coefficient of friction is an important parameter influences the stresses
and strains in the workpiece material and, hence, the quality of the product. Fig.2
shows the different friction areas when a deep drawing a cup. The region 1 is
friction area between sheet metal blank and holder and sheet metal blank die. The
region 2 is friction area between sheet metal blank and the die radius. The region 3
is friction area between sheet metal blank and the punch edge.
Table 1. Components of lubricants and coefficient of friction.
Lubricants
Components
% of Weight
Coefficient of
friction
A
Oil 20, herbal soap, fine
grafit, axit oleic
60: 10: 20:10
0,25
Oil 20, herbal soap,
0,24
B
small fine grafit, axit
60: 10: 20:10
oleic
C
Herbal soap, axit oleic
20:80
0,18
Without lubrication
0,29
Tạp chí Nghiên cứu KH&CN quân sự, Số 48, 04 - 2017
187
kỹ thuật & Kỹ thuật khí động lực
Figure 2. Friction areas when a deep
drawing a cup.
Figure 3. Components of lubricants
(A, B and C).
However, product quality is
improved
(reduce
walls
thickness) that
can be
controlled coefficient of friction. One of effective method is used of lubricants
during the deep drawing process [2]. The lubricants used in the study in Figure 3,
components of lubricants are shown in Table 1 [7].
The
paper
combines
simulation
and
experimental
study
effect
of
lubricant
process with different lubricants in deep drawing walls thickness. The coefficient
of friction is
examined at the lab of
Department of
Machinnery Mechanics –
Military Technical Academy (by Friction multifunction equipment - UTM) [3,5].
The research results order to reduce the minimum thickness of sheet metal in the
deep drawing, selection of reasonable lubricants ,contribute to improve product
quality and meet the requirements of the working conditions of the product.
2. SIMULATION OF DEEP DRAWING PROCESS
2.1. Model of simulations
Respondents are the step 1 of the circular cup. The product of basic geometrical
parameters and geometry model are shown in Figure 4.
Table 2 shows the material properties [8]. Material model is presented in Fig 5.
Table 2. Mechanical properties of SUS 304.
Steel
Mechanical properties of material
SUS 304
(MPa)
240
(MPa)
520
(%)
38
HB
88
The software Dynaform is used to simulate step 1 in deep drawing process.
Drawing ratio is 0,6. Coefficient of friction is used corresponding to the value in
the table 1[3,4] (corresponding to the lubricants A,B, C). Speed of the punch is 15
mm/s.
188
N. T. An, N. M. Tien, “Effect of lubricants on wall thickness… deep drawing process.
Nghiên cứu khoa học công nghệ
a)
b)
Hình 4. The 2D drawing of semi-product of step 1(a)
Hình 5. The material
and geometry model (b).
model.
2.2. Simulation results
The study analyzes the deep drawing part from the thickness point of view. The
part measurement was made with simulation results. It’s been analyzed 10 points
along the part profile, the points density is higher and radius area [Figure 6].
Where Si is thickness of product after the first step, S0 is thickness of of the
workpiece (S0 = 1,2mm). Simulation results show in Table 3.
Table
3. Values of material thickness measured
from the center to the outside parts.
Point
Without
lubrication
Lubricant A
Lubricant B
Lubricant C
1
1,106
1,126
1,126
1,144
2
1,032
1,068
1,098
1,136
3
1,095
1,108
1,108
1,148
4
1,188
1,166
1,176
1,155
5
1,186
1,176
1,164
1,145
6
1,224
1,214
1,212
1,184
7
1,226
1,214
1,210
1,192
8
1,268
1,246
1,225
1,210
9
1,286
1,278
1,266
1,220
10
1,286
1,276
1,264
1,224
Δmax (%)
14
11
8,5
5,3
The influence of lubricant process with different lubricants in deep drawing on
the variation in thickness of the workpiece can be viewed using the graph in Figure
7. The maximum false of wall thickness (Δmax) is examined with corresponding
cases, too.
Tạp chí Nghiên cứu KH&CN quân sự, Số 48, 04 - 2017
189