investigation of the potential of different lubrication...

Faculty of Mechanical Science and Engineering Institute of Fluid Power

Investigation of the Potential of Different

Cooling System Structures for Machine Tools

1

Axis drives 1503 kJ (45%)

Cooling system 389 kJ (12%)

Cooling lubricant system 532 kJ (16%)

Lubrication system409 kJ (12%)

Hydraulic system 126 kJ (4%)

Other 369 kJ (11%)

SFB/Transregio 96Thermo-energetic Design

of Machine Tools

QH

Q̇E

Electrical cabinet

Rotary table

Main drive

• Introduction

• Cooling system structure design

• System modelling and validation

• Potential analysis of cooling structures

• Summary & outlook

Linart ShabiInstitute of Fluid Power (IFD)

Dresden

Shabi, Linart3/19/2018

Introduction

2

Thermo-energetic Design of Machine Toolswww.transregio96.de

QualityProductivity

Efficiency

Production processes (energy losses) thermal energy

Different generated heat temperature fluctuation

Temperature variation thermo-elastic deformation

Displacement of TCP reduction of machine accuracy

Challenges

Motivation

Thermal behavior of cooling systems not analyzed in detail

Energy demand of cooling system inadequate information

Previous projects efficient components & control strategies

Main goal uniform temperature, minimal energy demand


Cooling system structure design

Cooling system of DBF630

Cooling system cools three components

Centrally fixed displacement pump

Rotary table & main drive cooled directly

Cooling unit (heat sink) in the return flow

3

Schematic representation of cooling system of DBF630


Cooling system structure design

Cooling system of DBF630

Cooling system cools three components

Centrally fixed displacement pump

Rotary table & main drive cooled directly

Cooling unit (heat sink) in the return flow

Cooling system of DMU80

Cooling systems cools 13 components

Cooling unit (heat sink) bypass cooling

Electrical cabinet separate cooling unit

3-Way valve used as diverting valve

4

Schematic representation of cooling system of DMU80


p1 p3p2 p2

Heat flow

T1

T2

T2

p2, T2

Ch, Cth

Thermal resistance:

Throttle equation:

Pressurizing equation : Temperature equation:

System modelling and validation

Methodology of the model development thermo-hydraulic network modelling

Hydraulic & thermodynamic domain laws of electrical engineering (Kirchhoff’s circuit)

5

𝛼𝑖𝑛𝑠𝑖𝑑𝑒

Thermo-hydraulic network modelling





Heat transfer at the hoses is considered

6

𝑅𝑒 =𝐷𝐻 ∙ 𝑉

𝜈 ∙ 𝐴

𝑃𝑟 =𝑐𝑓𝑙𝑢𝑖𝑑 ∙ 𝜌 ∙ 𝜈

𝜆𝑓𝑙𝑢𝑖𝑑

𝑁𝑢 = 0.0235 ∙ 𝑅𝑒0.8 − 230 ∙ 1.8 ∙ 𝑃𝑟0.3 − 0.8 ∙ [1 +𝑑𝑖

𝑙

23

]

𝛼𝑖𝑛𝑠𝑖𝑑𝑒 =𝜆𝑓𝑙𝑢𝑖𝑑 ∙ 𝑁𝑢

𝐿𝐸𝑛𝑓𝑜𝑟𝑐𝑒𝑑 𝑐𝑜𝑛𝑣𝑒𝑐𝑡𝑖𝑜𝑛

𝛼𝑐𝑜𝑛. =2 ∙ 𝜆𝑐𝑜𝑛.

𝑑𝑜 ∙ 𝑙𝑛𝑑𝑜𝑑𝑖

𝑓𝑜𝑟 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 𝑠ℎ𝑎𝑝𝑒

𝛼𝑖𝑛𝑠𝑖𝑑𝑒Fluid

𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑜𝑛

𝛼𝑖𝑛𝑠𝑖𝑑𝑒 𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑜𝑛

Heat transfer mechanisms at the hose






7

𝛼𝑖𝑛𝑠𝑖𝑑𝑒Fluid

𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑜𝑛

𝛼𝑖𝑛𝑠𝑖𝑑𝑒 𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑜𝑛

Heat transfer mechanisms at the hose

𝛽 =1

𝑇∞

𝐺𝑟 = 𝛽 ∙ 𝑔 ∙ 𝐷3 ∙ (𝑇𝑤 − 𝑇∞

𝜈2

𝑅𝑎 = 𝐺𝑟 ∙ 𝑃𝑟

𝑁𝑢 = 0.6 +0.387 ∙ 𝑅𝑎 1 6

1 + 0.559 𝑃 𝑟 9 16 8 27

2

𝑓𝑜𝑟 10−5 < 𝑅𝑎 < 1012

𝑎𝑛𝑑 0 < 𝑃𝑟 < ∞

𝛼𝑜𝑢𝑡𝑠𝑖𝑑𝑒 =𝜆𝑎𝑖𝑟 ∙ 𝑁𝑢

𝐿

𝛼𝑜𝑢𝑡𝑠𝑖𝑑𝑒

𝛼𝑜𝑢𝑡𝑠𝑖𝑑𝑒






Developing Simulation model of the current cooling system

8

𝛼𝑖𝑛𝑠𝑖𝑑𝑒 𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝛼𝑜𝑢𝑡𝑠𝑖𝑑𝑒

Model development of cooling system in the simulation software

exemplified by DMU80Model parameters for the simulation model



Measurement on the machine tools different operating processes

Validation the simulation model high accuracy of the thermal and hydraulic quantities

9

Comparison of temperature development simulation and measurement

in the idle process of DMU80

0 166 332 498 664 830

Time in s

23

24

25

26

27

Te

mp

era

ture

in

°C

0 166 332 498 664 830

Time in s

23

24

25

26

27

Te

mp

era

ture

in

°C

0 166 332 498 664 830

Time in s

27

26

25

24

23

Te

mp

era

ture

in

°C

0 166 332 498 664 830

Time in s

27

26

25

24

23

Te

mp

era

ture

in

°C

Outlet temperature measurement

Inlet temperature measurement

Outlet temperature simulation

Inlet temperature simulation

Motor spindle Drive B axis

Spindle nut Z axis Rail secondary part X axisa

b

c

d

xY

ZB

C

f

e

Inlet temperature

Outlet temperature

a) Motor spindle

b) Drives B axis

c) Spindle nut Z axis

d) Secondary part X axis

e) Pump

f) Tank


Comparison of temperature development simulation and measurement

in the manufacturing process of DMU80

Outlet temperature measurement

Inlet temperature measurement

Outlet temperature simulation

Inlet temperature simulation

Motor spindle Drive B axis

Spindle nut Z axis Rail secondary part X axis

0 176 352 528 704 880

Time in s

24

25

26

27

28

Te

mp

era

ture

in

°C

0 176 352 528 704 880

Time in s

24

25

26

27

28

Te

mp

era

ture

in

°C

0 176 352 528 704 880

Time in s

24

25

26

27

28

Te

mp

era

ture

in

°C

0 176 352 528 704 880

Time in s

24

25

26

27

28

Te

mp

era

ture

in

°C




10

a

b

c

d

xY

ZB

C

f

e

Inlet temperature

Outlet temperature

a) Motor spindle

b) Drives B axis



e) Pump

f) Tank





Heat transport through the hydraulic pipe 1% of cooling unit performance (4.5 kW)

11

a

b

c

d

xY

ZB

C

f

e

Inlet temperature

Outlet temperature

a) Motor spindle

b) Drives B axis



e) Pump

f) Tank

Total heat transport through the hydraulic

hoses of the DMU80

0 166 332 498 664 83042

44

46

48

He

at

flo

w in

W

Time in s


Potential analysis of cooling structures

Deficit of the current cooling system structures

High energy consumption 12% DBF630, 26% DMU80 /4,12/

Investigation of cooling systems ineffectively cooling

Supplied cooling medium does not match the component demand

Pump performance does not match to thermal load

12

central, variable speed drive

unit with proportional valves

1

Structure 1

Decentralized, variable

speed drive units without

flow control valves

1

Structure 2

Decentralized, variable

speed drive units, tanks

and cooling units

1

Structure 3

Developing new

cooling system

structures

Cold fluid Hot fluid Mixed fluid with predefined temperature

fixed drive unit with

constant flow valves

Current structure



Design of the new cooling system structures

Individually component-specific supply (pump or proportional valve)

Controlled cooling volume flow minimizing energy demand

Precise temperature control homogenous temperature field at the component

Reducing of displacement of TCP enhance the machine accuracy

The control compares Tactual with Tset

controlling of cooling volume flow

Each component is supplied with a different

demand-oriented cooling volume flow

Inactive pump or valve Component’s temperature

doesn’t exceed predefined limits

13

Control strategy of structure 1

sensor signal

control signal

pump

actual temperature

Regelung

Electrical cabinet Rotary table

Motor spindle

Controlling

TSet

thermal connection

hydraulic connection

heat input / heat output

Thermal resistance

heat capacity

hydraulic capacity

adjusting valve

tank


Structure 1Current structure Structure 2 Structure 3Structure 3

Simulation results of new cooling structures in comparison to the

current cooling structure

1500 2000 2500 3000

Heat input in W

25

26

27

28

29

Te

mp

era

ture

in

°C

150 180 210 240 270 300

Heat input in W

25

26

27

28

29

Te

mp

era

ture

in

°C

150 180 210 240 270 300

Heat input in W

25

26

27

28

29

Te

mp

era

ture

in

°C

Electrical cabinet (EC) Rotary table (RT)

Main drive (MS)

1800 2400 3000 3600

Total heat input in W

0

4

8

12

16

20

Vo

lum

e f

low

in

l/m

in

Temperature current system

system structure 1, 2, 3



current system

current system



Flow rate developments


Potential analysis structure 1, 2, 3

Stationary behavior of cooling system

Average equivalent heat flow

New cooling structures

Different Tset

Tactual constant

Volume flow control

Lower hydraulic power

Current cooling structures

No Tset possible

Tacutal depends from heat input

Uncontrolled volume flow

Higher hydraulic power

14



Comparison of the pumps performance in the current cooling

structure and in the new cooling structures

Current structure Structure 1 Structure 2 Structure 3


Potential analysis structure 1, 2, 3

Stationary behavior of cooling system

Average equivalent heat flow

New cooling structures

Different Tset

Tactual constant

Volume flow control

Lower hydraulic power

Current cooling structures

No Tset possible

Tacutal depends from heat input

Uncontrolled volume flow

Higher hydraulic power

15


Phydr. DBF 630 Phydr. DMU80

Phydr. Structure 1 / DBF630



1800 2400 3000 3600

Total heat input in W

0

80

160

240

320

400

To

tal h

yd

rau

lic p

ow

er

in W


Summary and outlook

Motivation and main goal

Reducing of thermo-elastic deformation enhancing of machine accuracy

Demand-oriented cooling system uniform temperature, minimal Energy demand

Deficits of current cooling structures

Cooling systems high energy consumption (12% to 26%)

Non-matching supplied cooling medium temperature fluctuation (ΔT= 3 to 5K)

Fixed speed drive high hydraulic energy

Benefits of new cooling structures

Controlled cooling medium flow minimization of energy demand

Matching supplied cooling medium temperature difference (ΔT= 0.2 to 0.4 K)

Variable speed drive lower hydraulic energy (53% to 70.5%)

16


Summary and outlook

Extension of simulation models

E-Motor, Frequency converter, etc.

Energetic evaluation of the overall system

Calculation of efficiency

Showing the energy flow paths

17


Summary and outlook






18


Summary and outlook






Development of a test rig

Practice investigation of cooling structures

Demonstrate the benefit of the structures

Experimentally sound statement

19


Summary and outlook






Development of a test rig

Practice investigation of cooling structures

Demonstrate the benefit of the structures

Experimentally sound statement

Coupling with a demonstration machine,

measurement TCP displacement

20

Technische Universität Dresden | Institute of Fluid Power | Chair of Fluid-Mechatronic Systems

Prof. Dr.-Ing. J. Weber | Tel. 0351- 463 33559 | [email protected]

Faculty of Mechanical Science and Engineering Institute of Fluid Power

21

Linart Shabi - [email protected]

Supported by:

SFB/Transregio 96Thermo-energetic Design

of Machine Tools

Thank you for your attention

investigation of the potential of different lubrication...

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