Basic HTML Version
Fluidic muscles
The previous system mechanically pulled
the bedplate from the engine block on
the linear axis. This then had to be
manually rotated 180° and set down
sideways on the workpiece carrier.
This was no small feat since the load
bearing crankshaft bed weighs
14 kg. When rotating and setting down,
there was a risk of injury from the sharp
outer edges of the cast aluminium part;
even wearing gloves couldn’t provide
sufficient protection. The new system
makes it all much easier. It does not
pull the bedplate off; instead it shakes
it free. Festo fast switching valves
oscillate a total of four Festo
fluidic muscles with 2 Hz, thereby
gently, but forcefully, releasing the
bedplate.
The fluidic muscle is a diaphragm
contraction system; in other words,
it is a tube that shortens under pressure.
It consists mainly of a hollow elastomer
cylinder with embedded aramid fibres.
When the fluidic muscle is pressurised,
its diameter increases and its length
contracts in a defined manner. This
enables a flowing, elastic movement.
Using the fluidic muscle enables motion
sequences that approximate human
movements in terms of kinematics, speed,
force, as well as finesse. It can exert ten
times the force of a comparably sized
cylinder, is very robust, and can also be
used under extreme conditions.
Control system on board
Another important function is fulfilled
by a Festo standard cylinder for weight
compensation. It supports operators
when lifting and lowering loads and
ensures that they can always operate
the semi automatic machine with the
same low level of force. A valve terminal
CPX/MPA safely and swiftly controls
a total of 22 pneumatic and electric
actuators for the system. The valve
terminal is attached to the rear side
of the special machine and travels
along with the system during all the
work steps. As the pneumatic control
could be attached directly to the
machine, only one slim Profibus cable
is connected to the control cabinet.
Models save time
Developing this innovative, special
machine took about 18 months. Following
the brainstorming and basic design
phases, Festo was included early on in the
development phase as a partner
providing advice on pneumatic solutions.
The aim was to create a small, compact
and especially lightweight design that
is suited to quick motion sequences.
The virtual 2D and 3D models from
Festo made the development phase
shorter and easier. In just a few clicks,
the development team was able
to download these models from the
Internet and integrate them into their
own design plans. A significant role
was played by the Festo FluidDraw
Pneumatic muscular
power:
four Festo
fluidic muscles shortly
before contracting
(left).
Pneumatics are on
board:
the valve
terminal CPX/MPA
is attached to the
system’s rear side;
only the Profibus
cable is connected
to the control
cabinet (top).
Directly to the
application:
the
pressure booster DPA
with the air reservoir
CRVZS increases the
5-bar pressure
to 6 bar in the system
by coupling (bottom).