Electro Mechanical Actuator – EMAFields of Application

Technical Information

KEY FEATURES

The EMA provides users with a complete package which is optimized and tested from the network connection to the piston rod. This includes pre-configured drive control parameters, software, firmware and technology functions for “alternating control” (closed loop bump less transfer between force and position control). Drive amplifier control cabinets complete the overall system.

▶ Dedicated for outdoor use in a harsh environment ▶ Large sizes available ▶ Designs available according recognized (civil)

engineering standards and guidelines ▶ Designs available with approval from a certifying

authority, such as marine & offshore applications ▶ Suitable to use an environmental friendly

bio-degradable grease ▶ Safety functions available up to SIL 3 and

performance level E

CONTENT

Product Description 2Structure 2Fields of Application 3Optional Features 3Customer Input 3Configurable 3Selection Example 4Technical Questionnaire 7System Code 8

▶ Maximum forces up to 1400 kN ▶ Stroke lengths up to 7,5 m ▶ The EMA provides installed power up to 50 kW

The portfolio according to the construction kit principle offers:

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PRODUCT DESCRIPTION

The electro mechanical actuator (EMA) is a heavy duty plug & run actuator especially developed for an outside harsh (salty) environment with high humidity and extreme temperatures. In comparison with the EMC-HD, which is dedicated for the Industrial market, the EMA is suitable for the civil and marine & offshore market. High forces in combination with large strokes are available.

The EMA provides users with a standard configurable electromechanical actuator including a control cabinet with an IndraDrive drive system. A smart, freely programmable drive system allows the realization of complex travel profiles (parameters for force, position and travel speed can be set as required over the complete working travel range).

STRUCTURE

The mechanics are based on proven planetary screw assemblies in a range of diameters of 48 to 120 mm and leads of 5 to 20 mm. The EMA uses electric power to drive the actuator. Driven by an electric motor, the spindle converts rotary motion of the electric motor into linear motion of the piston rod with high efficiency. The rod to head interface is sealed by a wiper to prevent dirt ingress. All flanged connections are sealed. The EMA is by default equipped with an anti-rotation feature to prevent torque on the external construction.

The main components of the EMA control cabinet comprise of an IndraDrive controller with technology function position-force control (PFC), an actuator with rotary encoder and optional load pin. Position control of

The selection of motor types on the applications requirements. A synchronous servo motor (SSM) is required if the speed / position accuracy is relative high, e.g. synchronous position control with multi-axis. An asynchronous servo motor (ASM) is more dynamic (lower inertia) in comparison with an asynchronous motor (AMO) according EN/IEC 60034 but is not suitable for every outside harsh environment.

the PFC uses the encoder as feedback. Force control uses a feedback signal of a load pin. It is also possible to drive the EMA in “open-loop” control, meaning movement stops when a limit switch is reached, or a maximum torque (current) is reached.

CONFIGURABLE

The size and type of an electromechanical actuator is mainly determined by the size of the spindle diameter and length. To determine the size of the spindle, following input is required; load case, stroke, speed and required lifetime in cycles. When the size of the spindle is deter-mined, the motor and gearbox can be sized. The size of the gearbox and motor are related to the maximum required spindle torque and speed. The gearbox ratio is related to the maximum torque and speed of the motor. The type of the motor depends on the required lifetime, protection class and selected options. Thereafter, the structural design can be made with input for mounting (e.g. clevis or trunnion). When the motor is sized, the frequency drive can be selected to control the motor. The customer deter-mines the (bus) interface, an IoT gateway is optional if desired.

Configuring an EMA

Rexroth calculations

Customer inputs

Force[kN]

Operating days(per year)

Lifetime[years]

Cycles[days]

Stroke[kN]

Temperaturerange [°]

Protection class[IP]

Overloadprotection

Mounting

Limit switches

Positionmeasurement

Speed[mm/s]

Manualoperation

Spindle size Motor type & size Structural design

EMA Configuration

Customer selection

Safetyfunctions Electronics Software Service

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FIELDS OF APPLICATION

Electro mechanical actuators can be used in a multitude of applications, and has the attributes to use it in an “outdoor harsh” environment. Examples are civil works, marine / offshore applications, crane industry, material handling etcetera. Featuring a conventional hydraulic cylinder look, hydraulic cylinders for example can be quickly replaced by electromechanical actuators to improve footprint and installation space.

OPTIONAL FEATURES

▶ Manual operation ▶ Limit switches ▶ Brake ▶ Manual brake release ▶ Safety functions ▶ Encoder / linear measurement system

KEY FEATURES

The EMA provides users with a complete package which is optimized and tested from the network connection to the piston rod. This includes pre-configured drive control parameters, software, firmware and technology functions for “alternating control” (closed loop bump less transfer between force and position control). Drive amplifier control cabinets complete the overall system.

▶ Dedicated for outdoor use in a harsh environment ▶ Large sizes available ▶ Designs available according guidelines, such as civil

applications ▶ Designs available with approval from a certifying

authority, such as marine & offshore applications ▶ Suitable to use an environmental friendly

bio-degradable grease

The portfolio according to the construction kit principle offers:

▶ Maximum forces up to 1400 kN ▶ Stroke lengths up to 7,5 m ▶ The EMA provides installed power up to 50 kW

On request, larger forces, longer strokes and a higher installed power may be realized outside the standard product portfolio.

ADVANTAGES

▶ Ready to install solution – pre-assembled, with only a few defined interfaces

▶ Sustainable, clean solution ▶ Easy startup – Plug & run ▶ Little maintenance expenditure – closed system,

diagnostics capable ▶ Energy efficient operation – power on demand ▶ Cost saving trough open standards in the control

concept ▶ “Safety on board” – functional safety integrated ▶ Remote access / I4.0 capability

ADVANTAGES EMA VS. EHA

▶ High energy efficiency and low negative environmental impact (no risk of leaks)

▶ Easy drive and control (no valves)

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SELECTION EXAMPLE

Step 1 Select your applicationThis application determines which standards need to be applied.

Table 1: Applications and its standards

Figure 1: Example of a load cycle

Civil Marine & OffshoreDIN 19704NEN 6786ROK / NBD

SB270USACE

Lloyd’s RegisterABS.

BVDNV-GL

Table 2: Example of a load cycle

Nr. Type of motion t [s] F [kN] s [mm] v [mm/sec]0 Rest 0 0 0 01 Accelerate 2,5 -60 30 152 Constant speed 77,5 -60 1200 153 Decelerate 80 0 1230 04 Pause 100 0 1230 05 Accelerate 102,5 -60 1200 -156 Constant speed 177,5 -60 30 -157 Decelerate 180 0 0 0

Step 2 Input cycle and desired lifetimeDefine a cycle time [t], load [F], stroke [s] and speed [v]. Then, define the operating cycles per day, operating days per year and required lifetime in years.

-70

-60

-50

-40

-30

-20

-10

0

10

20

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140 160 180

F [k

N] /

v [m

m/s

]

s [m

m]

t [s]

Stroke Speed Force

The average speed “nm” and average load “Fm“ are calculated. The average load is 60 kN. The actuator fulfills 24 cycles a day, 225 days a year and the desired lifetime is 20 years. This results in 108000 cycles in its desired lifetime. With a stroke length of 2460 mm per cycle, the desired lifetime in length is 266 km.

Calculations according R999001185 Screw Assemblies

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Step 3 Select the spindle according to load capacity and required lifetime

Step 3.1 Select a spindle according to bearing capacity

For the bearing capacity, it is important to determine if the actuator is pulling, pushing or multidirectional. In this example, only pushing loads are specified. Figure 2 shows the load capacity of the PLSA (planetary screw assembly).

Figure 2: Load capacity of planetary screws

0

200

400

600

800

1000

1200

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

F m[k

N]

Ls[mm]

PLSA 48 Pushing PLSA 60 Pushing PLSA 75 Pushing PLSA 99 PushingPLSA 48 Pulling PLSA 60 Pulling PLSA 75 Pulling PLSA 99 Pulling

Step 3.2 Select spindle according to lifetime requirementsFor the example case, the desired lifetime is obtained with PLSA 60x10, according Figure 3

When the desired lifetime would be reduced to 252 km (lifetime of 19 years) a spindle of 48x10 would already fulfil.

For the example case, the maximum force-stroke ratio is reached at 1230 mm were the maximum force is 60 kN. In this example the PLSA 48 fulfils.

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0

200

400

600

800

1000

1 10 100 1000 10000

Fm [

kN]

L10 [km]

PLSA 48x5 PLSA 60x10 PLSA 75x10 PLSA 99x20PLSA 48x10 PLSA 60x20 PLSA 75x20 PLSA 99x25

Figure 3: Lifetime of planetary screws

Step 4 Overload protectionIn civil applications, overload protection is required when complying to DIN19704. The overload protection absorbs the energy by meaning of a travel of the rod compared to the nut.

Step 5 Construction with motor and driveThe construction around the spindle ensures that the actuator meets the specified protection class. The actuator has a connection for the motor according to ISO 5210. Within our standard we offer the use of Rexroth servo motors (SSM/ASM) or standard asynchronous motor (AMO).

The PLSA are not self-locking, a holding brake may be required depending on the application.

Step 6 MountingThe external construction is determined for the shell and rod. Were the actuator is replacing a cylinder; mounting can be configured to match your current situation.

Product key of the configured actuator: EMA-48-60D1230/T4L-SSM160-2ESN

Figure 4: Mechanically configured actuator

STEPS TO FIND A SOLUTION

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Project description with picture

For target-oriented engineering, the following information must be available completely:

▶ Brief project description with picture(s) ▶ Cylinder orientation within the machine ▶ Additional boundary conditions ▶ Process sequence in the form of an F/s/t or F/v/t

profile

Please send inquiries to large.cylinders@boschrexroth.com

Cylinder orientation Motor orientation

α ……………………………° [ ] [ ] [ ]

Maximum pulling force static …………kN dynamic …………kN Operating cycles per day ……….. cycle(s)Maximum pushing force static …………kN dynamic …………kN Operating days per year ..……..…day(s)Operational stroke ………………mm Requested lifetime …………year(s)Spare stroke -……...……… mm +……...……… mm Linear speed ………..…mm/s

Ambient temperature Distance between actuator and cabinet ……………..………….…….moperational ….…….….℃ to ………..….℃ Rules and regulations …………………………….non-operational .………..…℃ to ………..….℃ Safety …………………………….Protection class IP-….. Submerged (depth&time) …………..m…….……..hExplosion protection ……………………….. Shock absorber [ ]Outdoors [ ] coastal [ ] Splash zone (fresh water) [ ]Indoors [ ] Splash zone (salt water) [ ]Dusty [ ] Chemical influences [ ]3-Phase [ ] Voltage ………...............………V1-Phase AC [ ] Frequency ……….............………HzDC [ ] Limit switches ………..….........…….qtyMotor brake [ ] Position measurement system [ ]Manual brake release [ ] Torque supervising [ ]Hand wheel [ ] Integral end position cut-off and

overload protection[ ]

SYSTEM CODE

01 Electro Mechanical Actuator EMA

Size02 Planetary roller screw Ø48 48

Planetary roller screw Ø60 60Planetary roller screw Ø75 75Planetary roller screw Ø99 99Planetary roller screw Ø120 120

Nominal force03 Maximum force in kN, e.g. 800 800

Rod coating04 Hard chromium plated C

Enduroq 2200 ROther X

Stroke05 Stroke length in mm, e.g. 3000 3000

Shell group mounting06 No external mounting 00

Mid flange E4Front flange E7Trunnion T4Other XX

Rod group mounting07 Threaded rod end G

Clevis with spherical bearing LFemale clevis ROther X

Motor type08 Synchronous servo motor SSM

Asynchronous servo motor ASMAsynchronous motor AMONon-standard motor NSM

Motor size09 e.g. 131 131

01 02 03 04 05 06 07 08 09 10 11 12 13

EMA – – / – –

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SYSTEM CODE

Switches10 Specify amount of limit switches, e.g. 2 2

Position measurement system11 Without N

With position encoder E

Shock absorber12 Without shock absorber N

With shock absorber S

Additional functions13 No additional functions N

With manual operation MOther *

01 02 03 04 05 06 07 08 09 10 11 12 13

EMA – – / – –

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Bosch Rexroth BVKruisbroeksestraat 15281 RV Boxtel, Noord-Brabant, NederlandPhone +31 (0) 411 – 651 951large.cylinders@boschrexroth.comwww.boschrexroth.com/largecylinders

© All rights reserved to Bosch Rexroth AG, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.The data specified above only serve to describe the product. No statements concerning a certain condition or suitability for a certain application can be derived from our information. The information given does not release the user from the obligation of own judgment and verification. It must be remembered that our products are subject to a natural process of wear and aging.

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