SIEMENS
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Siemens D 21.4 · 2017
14
Drive applications
Storage and retrieval machines
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Overview
Benefits to the power of three – outstanding productivity,
all-encompassing safety technology and optimized energy
efficiency
The more flexible, speedy and precise they are, the greater the
competitive edge they deliver: Storage and retrieval machines
are a core component of conveyor, logistics and stock move-
ment systems. They offer enormous potential for saving time and
money. Furthermore, they play a substantial role in reducing
energy consumption. Operator protection is another core issue
– the relevant requirements for storage and retrieval machines
are clearly defined in the C standard EN 528. As a complete
provider of components and systems, Siemens can supply the
solutions to all these challenges.
Throughput increased by up to 15 %
Siemens has developed the right solutions for raising the perfor-
mance of storage and retrieval machines. These are designed to
maximize acceleration potential while minimizing wear. They
also use sway control to reduce mast vibrations, helping to
deliver material savings.
Performance boost thanks to intelligent all-wheel drive
With two powered wheels on the chassis, the drive torque can
be distributed in such a way as to maximize acceleration and
prevent the drive wheels from spinning. Siemens can supply a
specially developed application that allows the drive torque to
be statically and dynamically distributed between both drive
wheels.
Integral sway control in drive increases throughput
Fast acceleration rates inevitably lead to mast vibration. With the
assistance of the SINAMICS technology extension VIBX (Vibra-
tion Extinction), this vibration can be prevented without restrict-
ing the dynamic performance of the machine. With VIBX, the ac-
celeration/deceleration of the travel axes is unable to excite the
natural frequency of the storage and retrieval machine. The fre-
quency can be adapted as a function of the cargo load and the
position of the load handling device while the machine is in op-
eration. There is no need to install a sensor to detect mast vibra-
tion. The sway control function is proven to shorten the time that
it takes a mast to reach a sufficiently still position to allow load
handling devices to move into a rack, pick up goods and move
out again so that the storage and retrieval machine can travel to
the handover station. This boosts throughput by up to 10 % and
also increases warehouse capacity. Thanks to the reduction in
wear and tear on the machine, less expensive materials can be
used in the machine construction. Energy consumption can be
reduced as a result of the lower masses.
By combining sway control (VIBX) with an intelligent all-wheel
drive, it is possible to boost performance by up to 15 %.
100 % compliance with DIN / EN 528 – standards-compliant
safety concepts
A comprehensive, but flexible safety concept is needed in order
to protect operator and machine and to optimize the entire plant.
Using the safety modules supplied free of charge by Siemens,
it is possible to implement safety concepts in accordance with
the storage and retrieval machine standard DIN EN 528. These
modules are certified by TÜV (German Technical Inspectorate)
and are therefore a "plug&play" solution. They are based on
Integrated Drive Systems. The optimum interaction between the
Safety Integrated functions of SIMATIC S7-F controllers and
SINAMICS S120 drives allows customers to develop their own
safety concepts. Siemens is offering concepts for warehouses
with reduced or without buffer area, safety strategies for systems
subject to slip and monitoring devices for typical storage and
retrieval machine applications (e.g. slack rope or overload
detection).
Up to 80 % reduction in grid power input – by use of
self-generated energy
Drives often need to brake heavy weights in hoisting applica-
tions. Frequency converters with energy recovery capability
help significantly reduce energy requirements. By using Line
Modules capable of regenerative feedback, energy can be
recovered and used to supply other loads. No braking resistors
are required which means that a smaller control cabinet and a
simpler cooling system can be used. Energy consumption is
balanced via the common DC link of the SINAMICS S120, so
minimizing the overall losses in the system. Furthermore,
Siemens has used ultracapacitors to implement a strategy
for storing energy in the DC link. In addition to reducing power
input by up to 80 %
1)
, electrical braking remains possible even
during power failures. Wear to brakes and wheels is also mini-
mized and the availability of the storage and retrieval machine
is increased.
1)
Applies to electromechanical systems with an overall efficiency of
90 %. With an efficiency of 80 %, the power input is reduced by 64 %.
© Siemens AG 2017