Bending
Dies 137
provides resistance to the bending operation, which is needed to perform the operation. An air cushion or hydraulic cylinders are used to generate the force necessary for this resistance. If the width of the
piece is large, it is necessary for the die to have a stripper. In the following description of a die set console,
the stripper 1 is fixed to the die shoe, and the punch holder has a slot so that the upper set of the tool can move up and down without obstruction when the press ram cycles.
10.2.2 V-Profile Bend Dies
Fig. 10.3 shows a simple die set for bending different shapes with bending angles of These
types of die are known as dies for V-profile bends. The die 1 is mounted on the die plate 4 in the conventional position. The punch 2 is attached to the punch holder 3. The pad 5 holds the blank
in position while it is being worked on. It also provides the resistance needed to perform the bending operation. An air cushion or hydraulic cylinders are used to power this resistance. The lower and upper
parts of the die set are guided by the guide post 7. The blank is positioned on the die
between the stop pins
and with a single stroke of the press the workpiece is bent into its required shape. Corrections to the punch angle, if necessary, are made after a try-out, when the exact springback angle
is known.
3 2
1 -die 2-punch
3-punch holder 4-die shoe
5-pressure pad 6-stop pin
7-guide post 8-cushion pin
9-workpiece
Final piece
Fig. 10.3
V-profile bend die.
Fig. 10.4 shows a single-operation bending die for a V-profile workpiece being bent on one end, with the other end of the piece already curled.
The die consists of a punch holder 3 and a die shoe 4 with guide posts 7. The guide posts are
press fitted into the die shoe and secured. The bending punch 2 is fixed to the punch holder with screws and dowels. The die shoe carries the die 1 the blank guide
and the stop pin 6. The pad 5 provides the resistance to the bending operation, needed to perform the operation. An air cushion or hydraulic cylin-
ders are used to power this resistance. The bent piece is ejected from the die with a pressure pad mechanism when the press ram is moved
to the “up” position.
138
Bending Dies
1 -die 2-punch
3-punch holder 4-die shoe
5-pressure pad 6-stop pin
7-guode post 8-blank suport
9-blank
1
0-workpiece Blank
Final piece
Fig.
10.4 Single operation bending die.
10.2.3 Universal Bending Dies
In Fig. 10.5 is shown a typical simple universal die and an example of a workpiece bent in four phases. The die consists of a die shoe
on which are assembled the universal die 2 and adjustable stops 3. The die has several slots of different shapes. The punch
is attached directly to the press ram. Selecting an appropriate profile on the die
2 with an appropriate punch 1 allows the workpiece to be bent into different shapes as desired.
1
-punch 2-die
3-adjustable stop 4-die shoe
Bending
phases
Fig. 10.5
Universal
bending die.
Bending Dies
139
10.3 DIES OF COMPLEX DESIGN
“Complex” refers to dies that are made up of many elaborately interrelated or interconnected parts. Considerable study and knowledge are needed to design complex die systems.
10.3.1 Closing Profile Dies
A bent profile often is used as a starting point for the next bending operation to be performed on the final piece. The composite drawing in Fig.
illustrates both “before” and “after” stages of a bending die for closing a U-profile bend. The closing die consists of a punch holder 1 and die shoe
which is guided by two guide posts and guide post bushings. The punch holder
carrries a housing with movable
side slides 4 that function as punches. Segments
6 are held in die shoe recesses with screws and dow- els. The workpiece U-profile, seen at the right, and in the die, with the insert 5 inside, is located on the
central die segment. When the press ram is moved down, the side slides of the punch slide toward the die segment and with a single stroke of the press, the workpiece is bent to shape. The springs 7 return the
slides to the start position when the ram press moves up.
1 -punch holder 1 -punch holder
2-die shoe
4-side slide 5-insert
6-segment of die
8-axle 9-security screw
10-workpiece Final piece
2-die shoe 3-holder
4-side slide 5-insert
Tnitial form 6-segment of die
7-spring 8-axle
9-security screw 10-workpiece
Final piece Fig.
10.6
Closing profile
10.3.2 Special Bending Dies
If great precision is required in the bent pieces, a special design of die is used for bending and coining operations. One design of such a die is shown in Fig. 10.7. The die consists of a punch holder 1 and die
shoe 2 with guide post and guide post bushing.
The punch holder carries the punch, which consists of an immovable segment 3 and two movable
segments which are arranged to move transversely as the die closes. Attached to the die shoe are the
die with stop pin
8
and stop latch 9. After the bending operation is finished, the fixed segment of the punch
3
pushes the slide punches 4
so
they move transversely and coin the outside of the workpiece.
