Dr. F. Desplentere [email_address] Heat removal within camera and software linking demo

Introduction Case study: Traffic control camera Case study: Mould temperature calculation for thermoforming Conclusions Overview

Introduction

Case study: Traffic control camera

Case study: Mould temperature calculation for thermoforming

Conclusions

History 1995: fusion of 5 former independent colleges 2002: associated with Catholic University of Leuven Locations Bruges Ostend KHBO

History

1995: fusion of 5 former independent colleges

2002: associated with Catholic University of Leuven

Locations

Bruges

Ostend

KHBO faculties

Campus Ostend Professional bachelor Chemics Electronics Mechanics Aviation Academic bachelor Civil engineering Electronics Mechanics Master courses Civil engineering Electronics Elektro technics Elektro mechanics Polymer technology

Professional bachelor

Chemics

Electronics

Mechanics

Aviation

Academic bachelor

Civil engineering

Electronics

Mechanics

Master courses

Civil engineering

Electronics

Elektro technics

Elektro mechanics

Polymer technology

Mechanical department 3-fold mission Education Service for SME’s Scientific research Overview of research fields Dynamic behavior of mechanical structures Polymer processing Avionics Different types of research Theoretical approach Material characterization Computer simulations Experiments …

3-fold mission

Education

Service for SME’s

Scientific research

Overview of research fields

Dynamic behavior of mechanical structures

Polymer processing

Avionics

Different types of research

Theoretical approach

Material characterization

Computer simulations

Experiments

…

Software overview General finite element package NX 6 Polymer processing Autodesk Moldflow : Injection moulding VEL 6.3 : Extrusion T-sim 4.7: Thermoforming

General finite element package

NX 6

Polymer processing

Autodesk Moldflow : Injection moulding

VEL 6.3 : Extrusion

T-sim 4.7: Thermoforming

Traffic control camera First case study

Traffic control camera

First case study Housing: Influence of different materials PA + PC ALU ≠ coatings All weather conditions Closed volume for air and humidity Extreme temperatures Solar heating Internal heat generation on 2 PCB’s 3.7 Watt Maximum allowed temperature on PCB’s = 100°C Radiation has to be taken into account Steady state conditions

Housing: Influence of different materials

PA + PC

ALU

≠ coatings

All weather conditions

Closed volume for air and humidity

Extreme temperatures

Solar heating

Internal heat generation on 2 PCB’s

3.7 Watt

Maximum allowed temperature on PCB’s = 100°C

Radiation has to be taken into account

Steady state conditions

Camera: model Mesh on solids and air+ assigning material

Mesh on solids and air+ assigning material

Camera: Situation 1 Simulation 1 = lab-conditions Ambient conditions=22°C Outside convection: 20W/m²K Heat generated on PCB: 3.7 Watt No solar heating

Simulation 1 = lab-conditions

Ambient conditions=22°C Outside convection: 20W/m²K

Heat generated on PCB: 3.7 Watt

No solar heating

Camera: Situation 1 Without taking into account radiation Maximum temperature: 91°C Maximum air temperature: 64°C

Without taking into account radiation

Maximum temperature: 91°C

Maximum air temperature: 64°C

Camera: Comparison Ambient temperature: 22°C Internal heat generation 3.7W Measurements for temperature with NTC’s in the internal air Simulation Experiment NOT OK 60°C  46°C 55°C  48°C 40°C  45°C

Ambient temperature: 22°C

Internal heat generation 3.7W

Measurements for temperature with NTC’s in the internal air

Simulation Experiment

Camera: Convection Calculated Internal natural convection coefficients: reasonable level

Calculated Internal natural convection coefficients: reasonable level

Camera: with radiation Taking into account radiation: first assumption black body Maximum temperature: 63°C Maximum air temperature: 50°C Maximum air speed 7 cm/s 63°C 50°C 7cm/s

Taking into account radiation: first assumption black body

Maximum temperature: 63°C

Maximum air temperature: 50°C

Maximum air speed 7 cm/s

Camera: Comparison Ambient temperature: 22°C Internal heat generation 3.7W Measurements for temperature with NTC’s in the internal air Simulation Experiment 48°C  46°C 52°C  48°C 39°C  45°C OK

Ambient temperature: 22°C

Internal heat generation 3.7W

Measurements for temperature with NTC’s in the internal air

Simulation Experiment

Camera: Solar Heating Possible heat load in NX Thermal/flow : solar heating Function of day number (angle of the sun) Function of location on the earth Function of time (turning of the earth) June at zenith: maximum flux 1415 W/m², ambient 40°C 85°C 73°C

Possible heat load in NX Thermal/flow : solar heating

Function of day number (angle of the sun)

Function of location on the earth

Function of time (turning of the earth)

June at zenith: maximum flux 1415 W/m², ambient 40°C

Camera: Material properties Influence of radiation parameters Outer shells 100% thermal transparant 97°C 64°C

Influence of radiation parameters

Outer shells 100% thermal transparant

Camera: Material properties Influence of radiation parameters Outer shells 100% thermal reflecting 74C 57C

Influence of radiation parameters

Outer shells 100% thermal reflecting

Second case study Software linking result: T-SIM - NX-Thermal – I-deas NX 5 Prediction of spatial temperature distribution for thermoforming mould Cooling behavior of thermoformed product Problem description T-sim ® does not perform heat transfer calculation for the mould Influence of cooling line geometry Product thickness is not known in advance General rules are not valid for thermoforming as for in injection molding

Software linking result: T-SIM - NX-Thermal – I-deas NX 5

Prediction of spatial temperature distribution for thermoforming mould

Cooling behavior of thermoformed product

Problem description

T-sim ® does not perform heat transfer calculation for the mould

Influence of cooling line geometry

Product thickness is not known in advance

General rules are not valid for thermoforming as for in injection molding

Thermoforming process

T-sim ® software Sheet representation New sheet Open sheet Preblown sheet Sheet sag (gravimetric deformation)

Sheet representation

New sheet

Open sheet

Preblown sheet

Sheet sag (gravimetric deformation)

T-sim ® software Thermoforming tools New tool Different formats Open tool

Thermoforming tools

New tool

Different formats

Open tool

T-sim ® software Process parameters: pressure, positions New process control Open process control

Process parameters: pressure, positions

New process control

Open process control

T-sim ® software Material data New material data Open material data

Material data

New material data

Open material data

T-sim ® software Heat and friction New Heat and friction Open Heat and friction One temperature for one tool!

Heat and friction

New Heat and friction

Open Heat and friction

T-sim ® software Project definition: selection of different files New Project Open Project

Project definition: selection of different files

New Project

Open Project

T-sim ® software Results Thickness distribution Temperature distribution Stress distribution Elongation distribution

Results

Thickness distribution

Temperature distribution

Stress distribution

Elongation distribution

Case study Temperature within thermoforming mould PP sheet: 0.5 mm thickness, Process temperature 160°C Serial cooling water flow 13 l/min, 13°C inlet value, Estimated mould temperature = 40°C Cycle time = 2 sec, t form = 0.5 sec, forming pressure 5 bar

Temperature within thermoforming mould

PP sheet: 0.5 mm thickness, Process temperature 160°C

Serial cooling water flow 13 l/min, 13°C inlet value, Estimated mould temperature = 40°C

Cycle time = 2 sec, t form = 0.5 sec, forming pressure 5 bar

T-sim simulation

T-sim results Thickness Temperature

Short cycle time  ± steady state Discontinue process  continuous Cooling of sheet : Transformation into power Need for Temperature and thickness distribution Realized through own developed program (Borland C++) Mould temperature

Short cycle time  ± steady state

Discontinue process  continuous

Cooling of sheet : Transformation into power

Need for Temperature and thickness distribution

Realized through own developed program (Borland C++)

Export of T-sim data (ASCII format) Nodes, elements, thicknesses, temperatures Subdivision into 100 thickness intervals Necessary for the creation of physical properties within I-deas For each element: calculation of power Determination of element surface Heat transported to mold (temperature assumed to be constant) For each time step within cycle time: Amount of heat transported Cooling down of element Procedure Local HTC Mould thickness Hot sheet cold mould

Export of T-sim data (ASCII format)

Nodes, elements, thicknesses, temperatures

Subdivision into 100 thickness intervals

Necessary for the creation of physical properties within I-deas

For each element: calculation of power

Determination of element surface

Heat transported to mold (temperature assumed to be constant)

For each time step within cycle time:

Amount of heat transported

Cooling down of element

Use of Universal file format (ASCII format) Export node and element data 100 Physical properties 100 Power groups Thermal Model

Use of Universal file format (ASCII format)

Export node and element data

100 Physical properties

100 Power groups

Heat flux field Boundary condition

Heat flux field

Thermal modeling of mould : assembly mesh Imported mesh + boundary conditions Thermal model built for mould in Ideas-TMG Steady state modeling Complete mould

Thermal modeling of mould : assembly mesh

Imported mesh + boundary conditions

Thermal model built for mould in Ideas-TMG

Steady state modeling

Contact surface temperature (average temperature) Temperature result Weighted average = 64.5°C Weighted standard deviation = 5°C

Contact surface temperature (average temperature)

Complete model (average temperature) Temperature result

Complete model (average temperature)

Complete model (average temperature) Coolant temperature Good fit with measured outlet temperature: 24.8°C  25.1°C

Complete model (average temperature)

Building of new model Transient model Contact surface temperature  Boundary condition Temperature result T-sim  Initial temperature for sheet Thermal coupling between two “surface” meshes Real cooling behavior

Building of new model

Transient model

Contact surface temperature  Boundary condition

Temperature result T-sim  Initial temperature for sheet

Thermal coupling between two “surface” meshes

Cooling behavior Good prediction of hot spots in thermoformed part Sheet cooling as function of time

Sheet cooling as function of time

Conclusions Combinations of programs allow to obtain more realistic data for average mould temperatures Guessing the average mould temperature for T-sim = past Optimisation tool for cooling line geometry is developed Future work: - Transient mould temperature prediction - Warpage of thermoformed products

Combinations of programs allow to obtain more realistic data for average mould temperatures

Guessing the average mould temperature for T-sim = past

Optimisation tool for cooling line geometry is developed

Future work: - Transient mould temperature prediction - Warpage of thermoformed products

October 2009