3 Fundamentals of press design

Sheet metal forming lines
higher stroking rate and reliable part transport. A special computer
program optimizes the motion curve of the transfer movements regarding
mass and acceleration so that the shortest possible cycle times
and extremely smooth movements are ensured for all stroking rates
(Fig. 4.4.30).
Motion curves are established for each transfer system and they are
used to check the clearance of the gripper rail system relative to the die
movement. A safety clearance of at least 20 mm must be ensured
between the tool and the curve in each case. All elements which may
impede this clearance, such as cam drives or gib elements must be taken
into consideration (cf. Sect. 4.1.6).
Electrically driven transfer
Instead of mechanical transfer systems, electrically driven systems can
also be used for large-panel presses (Fig. 4.4.31). The path, acceleration
and speed values of electrical transfers can be freely programmed,
which allows the system to be adjusted to different sets of dies.
stroke
[mm]
2600
2200
1800
1400
1000
600
200
0
transferreturn
withoutpart
lowergripperrails
opengripper
rails
Fig. 4.4.30 Motion diagram of a tri-axis transfer system
slidemo ement
closegripper
rails
parttransport
bytransfer
lift
gripper
rails
0 30 60 90 120 150 180 210 240 270 300 330 360
crank angle []
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
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