Mechanical Technology January 2016

Mechanical Technology — January 2016

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Innovative engineering

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Aventics AV valves are a valve technology

innovation that is pushing the boundaries of

electric/pneumatic hybrid products in terms

of space and energy efficiency.

All of Bosch Rexroth’s electro-hydraulics expertise is

integrated into the IndraMotion MLC control solution

software, which can replace elaborate programming with

parameterisation.

The EMC-HD electromechanical

cylinder is a powerful alterna-

tive to pneumatic and

hydraulic cylinders

that provides

energy efficiency

benefits.

can be placed on machines close to the

action, which can reduce compressed air

consumption by up to 20%.

Electric control

Electric control excels when absolute ac-

curacy of movement is required or when

continuous motion is needed. Electric

servo control is useful in such diverse

applications as CNC spindle controls in

machining centres and in lift-and-locate

applications for assembly operations.

Electronic servo control offers the

highest levels of precision, particularly in

closed-loop applications where feedback

allows the system to adjust to conditions.

For example, Bosch Rexroth offers the

System 300 advanced DC tightening

system, which allows for multi-stage

programming and multiple synchronisa-

tion of the spindle motors.

Since hydraulic and pneumatic ap-

plications use cylinders, they achieve

linear motion simply and easily. Electric

control is based on rotating motion and

requires a transition, such as a ball screw

or linear motor.

As energy efficient technologies

should be used more often, and pro-

cesses improved, electro mechanical

actuation should be considered as it

can offer many industrial areas a bet-

ter economic and energy use solution.

An experimental analysis conducted

by the University of Kassel in Germany

incorporating hydraulic, pneumatic and

electric actuators, proved that the latter

are the most energy efficient across the

three disciplines.

In conducting the experiment, a spe-

cific duty cycle was chosen and param-

eters set for real application simulation.

All actuators were mounted inline to have

the same required duty cycle, the speci-

fications for the choice of cylinders were

similar, and the set up ensured that differ-

ent loads could be chosen. A maximum

load of 100 kg was used and standard

hydraulic and pneumatic components

used, with the electro mechanical actua-

tor being an integrated actuator.

The measured energy consumption

was multiplied by the number of operat-

ing hours and extrapolated to the real

need during one year – with 6 000 hours

per year taken as a basis. An air cylin-

der’s energy requirements worked out

to 8 980 kWh per year, hydraulic at

3 602 kWh for the same period and

the electro mechanical alternative only

816 kWh. CO

consumption for the

pneumatic system worked out to 5.3 tons

a year, with 2.3 tons from the hydraulic

system and only 525 kg resulted from

the electro mechanical equivalent. Thus,

a saving of 90% was achieved compared

to the pneumatics-only system and 77%

compared to the hydraulic cylinders.

An energy consumption-based com-

parison shows that hydraulic actuators

needs 4.4 times more energy for the

same duty cycle and a pneumatic cyl-

inder needs 10 times more energy com-

pared to electro mechanical actuators.

The electronics in Aventics AV valves

(mentioned under pneumatics above) in

these applications support all standard

fieldbus and Ethernet protocols, which

realise control and communication tasks.

The sensors also feature IO-link inter-

faces, allowing them to exchange data

with the control for diagnostic functions or

parameterisation. For example, the Bosch

Rexroth EMC electromechanical cylinder

has an optional force sensor, which allows

decentralised process controls without a

higher-level control system.

The EMC-HD is a powerful alternative

to pneumatic and hydraulic cylinders

and provides benefits in terms of en-

ergy efficiency. It provides an advanced

control technology advantage, even at

high forces

– force, position

and speed can be free-

ly parameterised – and its

flexibility means it can be adapted to

new tasks via the drive system. It is an

electromechanical heavy-duty cylinder

that transmits motor movement via ball

or planetary screw drives, depending on

the dynamics and force requirements.

Hybrid solutions

There are a number of factors to consider

when selecting technology for a specific

system: accuracy and repeatability, ap-

plication complexity, speed flexibility,

reliability, maintainability and lifecycle

costs.

The convergence of production IT

and business IT, the synchronisation

of processes as well as decisions taken

autonomously by machines in real-time,

have enabled the Hytec Group, through

its relationships with Bosch Rexroth and

Aventics, to provide accurate, efficient,

customer-specific manufacturing prod-

ucts and solutions.

Industry 4.0 and the resultant hybrid

automation solutions represent better

resource allocation, higher efficiency,

individuality and profitability. The Hytec

Group is Industry 4.0 ready, with a num-

ber of safety-compliant hybrid solutions

that integrate electric/pneumatics, elec-

tric/hydraulics and now even pneumatic/

hydraulic/electric solutions.