3 Fundamentals of press design

92 Fundamentals of press design
are pushed over the press bed, while the slide is lowered vertically on
the upper dies. The task of classifying the different clamping systems is
excessively complex, as the selection depends heavily on the required
clamping force, the type of die and press involved and the degree of
press automation.
Small dies are generally held by push-in clamps or clamping rails.
The rails are fixed on the clamping plate, while push-in clamps are
inserted into the T-slots on the clamping plate. The advantage of working
with this type of small, lightweight fixture is that it restricts the
usable table surface only minimally and permits easy handling. If the
clamping force of the push-in clamps is not sufficient when connected
to the hydraulic system of the press at 250bar, it can be increased to
50kN by raising the line pressure to 400bar.
T-slot clamps are frequently used to secure medium-sized dies
(Fig. 3.4.7). A pressure of 250 bar is applied to the clamping cylinders by
the press hydraulic system. As a result, a clamping force of up to 200kN
can be generated. The clamps can be released by means of spring power
after a drop in the oil pressure. The safety of the fixture is guaranteed
by positive locking action in the T-slot and monitored by pressure sensors
which bring the press to an immediate standstill in case of a drop
in pressure. For large dies with differing widths, it is necessary to use
T-slot
clamped released
hydraulic
push-in-clamp
slide
clamping
plate
upper die
Fig. 3.4.6 Different die clamp designs
hydraulically electro-
hydraulically
electromechanicallymechanically
swivel-pull clamp
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
rotary-pull clamp