0
Friction Related Explicit
Calculations in the
Vending Machine Sector
June 24-26, 2014 - Munich
1
Matteo Adobati
matteo.ado...
2
Contents
1. N&W Group
2. R&D Department
3. Scope
4. Tea infusion sliding piston
5. Sugar dispenser sliding system
6. Con...
1. N&W Group
10.000 customers
200.000
150.000
OCS and Horeca machines / year
Vending machines / year
500suppliers
Worldwid...
4
Brands & product ranges
Vending O.C.S. Ho.Re.Ca.
1. N&W Group
550
Innovation, design, excellence
1005%
• A consolidated project management approach
• Structured working flows and proce...
Friction issues
Project targets
6
3. Scope
• Sliding [plastic/rubber] - [plastic/plastic] - [steel/plastic]
• Changing geo...
7
4. Tea infusion sliding system
4.1 – Finite element model
Tea-Brewer
Tea-leaves infusion
mechatronic dispenser
N&Wpatent...
8
4. Tea infusion sliding system
4.2 – Contact surfaces
Infusion chamber - Rubber Gasket
Rubber Gasket - Sliding piston
9
4. Tea infusion sliding system
4.3 – Material & contact
• Material:
 Infusion Chamber - PEI (Polyetherimide)
 Rubber g...
10
4. Tea infusion sliding system
4.4 – Friction behaviour
Contact pressure (dry condition)
Piston positions:
UP:
t_step: ...
11
4. Tea infusion sliding system
4.5 – Results & test compaign
12
4. Tea infusion sliding system
4.6 – Conclusion
• Explicit analysis able to predict the rubber behavior
• Good support ...
13
5. Sugar dispenser sliding system
5.1 – Finite element model Solvers:
• Optistruct NLSTAT/NLGEOM
(preliminary analysis)...
14
5. Sugar dispenser sliding system
5.2 – Contact surfaces
Cap - slider
Slider - frame
Cap - frame
Slider - fork
Fork - p...
15
5. Sugar dispenser sliding system
5.3 – Material & Contact
- Material: POM (Polyoxymethylene)
- Material numerical form...
16
5. Sugar dispenser sliding system
5.3 – Friction behaviour
- Numerical – experimental data correlation
Fu
Cam rotation ...
17
5. Sugar dispenser sliding system
5.4 – Results
18
5. Sugar dispenser sliding system
5.5 – Conclusion
• Explicit simulation very close to real dynamic mechanism
• Predict...
19
Thank you for your attention!
Any questions?
www.nwglobalvending.com
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FRICTION RELATED EXPLICIT CALCULATIONS ON VENDING MACHINE SECTOR

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Our day life is characterized by the use of vending machines. We are used to get cans, bottles, snacks, coffee from a big variety of vending machines spread out everywhere. From an engineering point of view what is inside a vending machine is an incredible mess of mechanical and electrical components working together, cooperating, heating, cooling in a lot of different external and internal conditions. This means that the design of a vending machine and of its components has to be robust, reliable and affordable. N&W, as market leader in vending sector (EU and a strong presence WW) and with a 70 people R&D Dep., has faced many problems related to sliding plastic/rubber components in presence of friction issues due to moisture, sugar powder (micro and macro), heat transients and pressure. To do that a testing campaign has been performed in order to achieve all the data needed to characterize friction coefficients relevant for the numerical activities.

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Transcript of "FRICTION RELATED EXPLICIT CALCULATIONS ON VENDING MACHINE SECTOR"

  1. 1. Friction Related Explicit Calculations in the Vending Machine Sector June 24-26, 2014 - Munich 1 Matteo Adobati matteo.adobati@nwglobalvending.com Fabio Rota fabio.rota@nwglobalvending.com
  2. 2. 2 Contents 1. N&W Group 2. R&D Department 3. Scope 4. Tea infusion sliding piston 5. Sugar dispenser sliding system 6. Conclusion
  3. 3. 1. N&W Group 10.000 customers 200.000 150.000 OCS and Horeca machines / year Vending machines / year 500suppliers Worldwide presence To be the leading producer of coffee-based drink and snack & food dispensers world-wide, by delivering an unrivalled and consistent consumer experience. Caring for our customers, our people and the environment are the keys to our success. 1.500 3 6 15manufacturing sites world-wide branch officeseuropean R&D centresemployees 3
  4. 4. 4 Brands & product ranges Vending O.C.S. Ho.Re.Ca. 1. N&W Group
  5. 5. 550 Innovation, design, excellence 1005% • A consolidated project management approach • Structured working flows and procedures on both Product and Innovation development processes • Product development supported by advanced virtual validation methods in both Design and Lab test stages 5 2. N&W R&D Department Percentage of the turnover invested in R&D Engineers in R&D Registered patents
  6. 6. Friction issues Project targets 6 3. Scope • Sliding [plastic/rubber] - [plastic/plastic] - [steel/plastic] • Changing geometries during movements • Dry/wet surface interaction • Presence of sweetening powder or moisture • Contact pressure • Heat transient condition • Investigate the contact finding the right LAW • Friction coefficient charaterisation - static/dynamic • Testing campaign vs FEM results comparison • Mechanical solution optimization:  contact force/pressure decrease  robust and reliable assembly
  7. 7. 7 4. Tea infusion sliding system 4.1 – Finite element model Tea-Brewer Tea-leaves infusion mechatronic dispenser N&Wpatentregistered Solvers: • Optistruct NLSTAT/NLGEOM (preliminary analysis) • Radioss 3D & FEM model Boundary conditions: • Infusion chamber: 1 DOF (z axis) • Piston: grounded fixed • Chamber movement: IMPVEL (z axis) Piston Rubber gasket Infusione chamber Elements: • Hexa8 (# 120000)
  8. 8. 8 4. Tea infusion sliding system 4.2 – Contact surfaces Infusion chamber - Rubber Gasket Rubber Gasket - Sliding piston
  9. 9. 9 4. Tea infusion sliding system 4.3 – Material & contact • Material:  Infusion Chamber - PEI (Polyetherimide)  Rubber gasket - Sylicon rubber 60 Shore  Piston - PEI (Polyetherimide) • Material numerical formulation:  PEI (Polyertheremide) - Elastic - LAW1  Sylicon rubber - Ogden - LAW42 • Type7 contact interfaces • Contact parameters environment:  Assembling rubber preload  Wet (low friction) / Dry (worst case)  Changing piston motion direction [down - up] Sliding piston Supplier rubber graph used to define the Ogden law parameters: E = 4.5 Mpa 1 = 0.948 Mpa 2 =-0.236 Mpa
  10. 10. 10 4. Tea infusion sliding system 4.4 – Friction behaviour Contact pressure (dry condition) Piston positions: UP: t_step: 0,5 s Phase: Plug + sliding down: Piston Force: Fmax = 2.5 N DOWN: t_step: 4,5s Phase: Reverse direction: Piston Force: Fmax = 12 N Transient cycles: t = 0,0  0,5 s Piston plug t = 0,5  4,4 s Sliding down t = 4,4  4,6 s Reverse direction t = 4,6  6,5 s Sliding up Normal Tangential
  11. 11. 11 4. Tea infusion sliding system 4.5 – Results & test compaign
  12. 12. 12 4. Tea infusion sliding system 4.6 – Conclusion • Explicit analysis able to predict the rubber behavior • Good support to calibrate material blend • Samples reduction vs final solution design • Good contact response despite of relevant mechanical clearances presence • Good understanding on dynamic mechanism performances friction’s influence • Good driver to improved solutions
  13. 13. 13 5. Sugar dispenser sliding system 5.1 – Finite element model Solvers: • Optistruct NLSTAT/NLGEOM (preliminary analysis) • Radioss • Motionsolve Boundary conditions: • Fork: 1 DOF (axis rotation) • Plate: grounded fixed • Fork rotation: IMPVEL • Cap spring: CLOAD Elements: • Tetra10 (# 126000) • RBE2 (# 6)
  14. 14. 14 5. Sugar dispenser sliding system 5.2 – Contact surfaces Cap - slider Slider - frame Cap - frame Slider - fork Fork - plate
  15. 15. 15 5. Sugar dispenser sliding system 5.3 – Material & Contact - Material: POM (Polyoxymethylene) - Material numerical formulation – Law1 - Type 7 contact interfaces - Contact parameters environment: > humidity / temperature > sugar powder accumulation during lifecycle > mechanical clearances
  16. 16. 16 5. Sugar dispenser sliding system 5.3 – Friction behaviour - Numerical – experimental data correlation Fu Cam rotation [°] Sliding force [N]
  17. 17. 17 5. Sugar dispenser sliding system 5.4 – Results
  18. 18. 18 5. Sugar dispenser sliding system 5.5 – Conclusion • Explicit simulation very close to real dynamic mechanism • Predictive solutions to optimized configuration design • Good contact response despite of relevant mechanical clearances presence • Good understanding on dynamic mechanism performances friction’s influence • New leverages’ design • Friction environment new mechanism robustness
  19. 19. 19 Thank you for your attention! Any questions? www.nwglobalvending.com
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