142
Bending
Dies
Blank
Final
A
1
-cam
slide 2-driver
3-driver plate 4-upper shoe
5-shank 6-pressure pad
7-spring 8-slide
9-spring suport
1 1
-die guide lath 12-lower shoe
13-workpiccc
Fig. 10.9
Curling die design.
10.3.4 Tube-Forming Dies
Tube-forming dies may be single or multiple. Fig. 10.10 shows a single die for forming a tube in three phases. The edges of the blank are bent in the first phase between the punch
1 and the die 2. The pressure pad 10 holds the blank in position while it is being worked
on, and provides the resistance needed to perform the operation. The spring 1 1 provides resistance to the pressure pad. The work-
piece is transferred by hand from the first position, phase one, to the second position, phase two. At the same time, a new blank is located at the first position. In the second phase, the workpiece is bent
between the punch
3 and the die 4. The workpiece is then transferred to the third position, the sec- ond workpiece moves to the second position, a new blank is located at the first position, and
so on. At phase three, the third position, forming
of the workpiece is completed between the punch the die
and the insert 7.
Even though each single press stroke makes one new piece after the completion of the first, produc- tivity
of this die design is low because the workpiece is transferred by hand. For mass production, the
process needs to be automated. For production of more precise tubular pieces, a much better design for the
die is shown in Fig. 10.1 1.
The tube-forming die in Fig. 10.1 consists of the punch holder
1 0, die shoe 1
with guide sys-
tem: guide post 8 and guide bushing
9. The punch 1 and driver 5 are attached to the punch holder. The die cam
the die segment and the cam slide die
with springs 6 and
are fixed to the die shoe.
Bending Dies
143
Blank Phase
I
Final piece 7-insert
13-cushion pin 2-die
8-punch holder 14-workpiece
9-die shoe 4-die
10-pressure pad 5-punch
6-die 12-blank stop
Fig.
A single die
for forming
a
tube.
blank
,
1
-punch
8-guide
post
2-half
segment die
3-cam
slide die 9-bushing
1
0-punch holder
Fig. 10.1
Tube-forming die. In operation, the blank 12 is located on the cam slide die. At the beginning of the bending oper-
ation, the blank is free bending. At the end of the downstroke of the press, the driver 5 pushes the
die segments 3 to coin the workpiece around the punch 1 into its final dimensions. On the upstroke
of the press, the springs 6 and 7 return the die segments to the start point and the tube is slipped off the punch
144
Bending Dies
10.3.5 Multiple-Bend Dies
Multiple-bend dies offer an infinite variety of possibilities. used in mass production, these dies
can accomplish, in a single stroke, an operation that would require several operations with a single-bend die. Such a die requires much greater pressures than do dies for individual operations, and an example is
shown in Fig. 10.12.
1
-punch 2-die
3-pressure pad 4-ejector
5-spring 6-spring
shoe holder
9-guide post bushing
1
O-guide post
1
l-workpiece
Fig. 10.12
Multiple-bend
die.
Blank
Phase
I
Phase
Final piece
Attached to the punch holder 9 is the punch
whose inside surface has the function of a die dur- ing the final bending phase. The die shoe carries the die 2 and the pressure pad
with the spring 5. The pressure pad functions as a punch during the final bending phase. The first blank is bent into a
file by the action of the outside of the punch 1 and the die 2. Then the pressure pad 3 and the inside
of the punch 1 act to form the final shape of the piece. The piece is removed by means of the ejector 4 and the spring
located in the upper set of the die.
10.3.6 Combination Dies
A
combination die is a simple-station complex die in which both cutting and non-cutting operations are
accomplished at one press stroke. An example of such a die is shown in Fig. 10.13.
The die in Fig. 10.13 consists of the punch holder the die shoe
with guide post
and the guide post bushing 1. The punch holder carries the bending punch which functions as
a punch plate for the punch 4. The punch bears the pressure pad
and the spring 15 is also attached to the punch holder as well as the strip cutting punch 1
3.
