fastening & assembly solutions and technology - Approved Business

Improved accuracy for servo press range
Press or interference fit of parts is a
quick and simple method of joining
parts. A part is pushed into a recess,
which is slightly undersized causing
interference. The fit is made possible
by the material elasticity, which
gives rise to a compressive force
between the part and the recess. The
join is maintained by the friction,
which is usually a function of this
compressive force.
Kistler has recently expanded
its range of NCF servo press systems
with the introduction of the
NCFT-B for low force interference
fit processes, for forces below 1 kN.
The company’s servo press actuators
range includes a piezoelectric
force sensor and a rotary encoder to
measure and control position. The
actuator is linked to a servo controller
and a program/monitor unit.
The NCFT has been used where the
limited position and speed control
offered by pneumatic systems, is
inadequate. Most applications have
been on plastic parts with a high
quality requirement, such as drug
delivery devices.
NCFT-B is a development of an
earlier design that improves the
accuracy of low force measurements.
A force sensor mounted on
the end of the shaft eliminates any
force measurement uncertainty due
to friction in the bearings. The
piezoelectric force sensor offers two
selectable calibrated force ranges,
allowing the same NCFT-B to
switch between operations with differing
force requirements.
It is possible to specify a series
of positions and speeds accurately
and clearly define the fit process. A
position repeatability of better than
0.005 mm and a speed greater than
300 mm/s is possible. A fit program,
consisting of a series positions and
speeds, can be entered into the control
electronics. For some operations
force feedback can be used.
Alternative control programs can
easily be selected by a master PLC
for different parts and materials.
Bellows grippers provide
for fragile assemblies
Pneumatics leader Festo has
launched a range of bellows grippers
that provide an automation solution
to the problem of transporting or
holding fragile workpieces. The
DHEB series grippers employ flexible
bellows which expand in diameter
when actuated by an integral
pneumatically-driven piston, to
securely grip the interior
surface of a workpiece.
The grippers are single-acting
devices, which
simplifies their control
significantly. When their
air supply port is pressurised,
an internal piston
optionally draws a wedge
up or down within a rubber
bellow, causing it to
deform outwards to meet
and conform with the
interior contour of the
workpiece, such as the
neck of a bottle. This provides
a secure but gentle
air-tight grip, which is
maintained until the air supply port
is exhausted, whereupon the force of
the bellows returning to their original
shape pushes the piston back into
its initial position.
There are two versions, offering
a choice of bellows activation directions
to suit different handling
machine actions; one uses an
upward piston stroke to
deform and expand the
bellows, the other uses a
downward stroke.
Furthermore, the grippers
are not limited to
gripping the inside of
workpieces - multiple
units can be configured
for grasping external surfaces,
such as the edges
of a printed circuit board.
The tools are available
with
11 choices of contiguous
bellow sizes, ranging
from 8 to 63 mm.
FESTO 01252 775000
FAST OCTOBER 2011
FASTPRODUCTS: Assembly systems
The degree of control offered by
electrical systems greatly exceeds
that offered by pneumatic systems.
The monitor unit applies a series
of tests to the force/displacement
curve to provide a quality assessment
of all parts. The monitor unit
can retain or export manufacturing
statistics, as required.
Maintaining and running a
pneumatic or hydraulic circuit
usually has a greater energy
demand and therefore
higher operating
costs than equivalent
electrical
systems. An electrical
system has
the benefit of only
using energy when
required, which greatly helps to
improve its energy efficiency.
The NCFT offers a compact and
low weight design. The 1kN servo
press actuator module is just 551
mm long, with a mass of 5.8 kg.
This makes the NCFT suitable for
Specialist applicator manufacturer
PC Cox has launched two pneumatic
sealant and adhesive applicators,
which have already generated significant
interest with orders placed
in Russia and Japan.
Jetflow3 is a multipurpose applicator
that outputs both bead and
spray and can replicate the highly
accurate spray patterns crucial in
sectors such as automotive repairers
and refinishers. The applicator is
simple to change from bead to spray
and is ideal for use with all conventional
and sprayable low to high viscosity
sealants.
The company believes that Its
easy and accurate regulation of
incoming air flow means there is no
other applicator available currently
that provides this level of flexibility
and controlled delivery. It is also the
only pneumatic applicator that can
convert between cartridge and
sachet; the Jetflow3 does it all, spray,
lay beads and accept cartridges,
sachets or pouches, it is claimed
difficult locations
and manipulation by
robots.
For manufacturing process
where a small number of fit
operations are required and there is
no pre-existing hydraulic or pneumatic
circuit, an electrical system is
a simple and low cost
addition to a manufacturing
facility.
KISTLER INSTRUMENTS
01256 741550
Pneumatic applicators
are well received
The latest in the Airflow series,
the Airflow3, is a single component
pneumatic bead applicator
ergonomically designed for industrial
applications and has already been
short-listed for a design award.
PC Cox tells us that it is a more
efficient, modern and aesthetically
pleasing applicator that is straightforward
to use in the application of
low to high viscosity sealants. A
built in silencer delivers a quieter
operation and integrated air connectors
offer greater protection, as there
are no exposed parts. An integrated
air pressure regulator allows for precise
and smooth flow control. The
Airflow3 takes pouches, sachets or
cartridges. There is also a combi version
accepting sachets and cartridges.
Both new products have been
ergonomically designed to be light
and comfortable to handle, allowing
longer usage time to aid manufacturing
productivity.
PC COX 01635 264500
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