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Nono Convegno                       9     Torino, 7-9 Settembre 2009Tube Free Bending: a new index for the control of the ...
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A. Mentella aitem 2009

  1. 1. Nono Convegno 9 Torino, 7-9 Settembre 2009 Tube Free Bending: a new index for the control of the cross section quality Alessia Mentella Matteo Strano Roberto Gemignani alessia.mentella@unicas.it matteo.strano@polimi.it roberto.gemignani@blm.it UNIVERSITY of CASSINO POLITECNICO di MILANO Stefano FarinaDept. of INDUSTRIAL ENGINEERING Dept. of stefano.farina@blm.it Cassino (FR), ITALY MECHANICAL ENGINEERING Milano (MI), ITALY BLM GROUP Cantù (CO), ITALY
  2. 2. 9 Nono Convegno Torino, 7-9 Settembre 2009 OUTLINE Introduction • Chemical, physical and technological properties of copper • Most typical applications of copper tubes • Technical Standards Rotary-draw bending • Free bending: configuration of the tools • Free bending: process limits and quality indicators Design of Computer Experiment • Preliminary results with standard tools • Description of the FEM model and its experimental validation • Results with modified tools and comparison Modelling and improving the quality of the section • Correlation analysis among the quality indicators and development of a unique estimator • Conclusions 2/20Alessia Mentella - alessia.mentella@unicas.it
  3. 3. 9 Nono Convegno Torino, 7-9 Settembre 2009 INTRODUCTION Chemical and Physical Properties 0.014%≤ P≤0.040% Cu-DHP Cu+Ag: min 99.90% Valore Parametro Chimico-fisico Caratteristica Applicazione parametro Elevata resistenza al fuoco Impianti idro-termo- Temperatura di Fusione 1083°C e alle alte temperature (A1) sanitari Coefficiente di dilatazione 1,65*10-6 Ottimo per accoppiamenti Pareti e pavimenti termica a 20°C m/(m*K) multimateriale radianti Pannelli Radianti; Conduttività Termica a 20°C 391 W/(m*K) Ottimo conduttore termico Scamb. di calore Resistività Elettrica a 20°C 0.0173 Macchine statiche e Ottimo conduttore elettrico (ricotto) Ohm mm2/m dinamiche Potenziale E° Elevata resistenza alla Impianti marini 0.337 V (Cu2++2e- Cu) corrosione offshore 3/20Alessia Mentella - alessia.mentella@unicas.it
  4. 4. 9 Nono Convegno Torino, 7-9 Settembre 2009 INTRODUCTION Copper tubes applications Metal or Thermal conductivity % Alloy Wm-¹ C-¹ Ag 420 115 Cu 364 100 Au 299 82 Al 82 58 Bronze 58 ÷ 65 17 Brass 70 ÷ 116 19 ÷ 32 Zn 110 30 Ni 58 ÷ 65 19 Sn 64 18 Steel 29 ÷ 105 8 ÷ 29 Ti 16 5 4/20Alessia Mentella - alessia.mentella@unicas.it
  5. 5. 9 Nono Convegno Torino, 7-9 Settembre 2009 INTRODUCTION Copper tubes applications GAS ACQUA POTABILE Impianto idrosanitario San Raffaele, Milano CONDIZIONAMENTO/REFRIGERAZIONE 5/20Alessia Mentella - alessia.mentella@unicas.it
  6. 6. 9 Nono Convegno Torino, 7-9 Settembre 2009 INTRODUCTION Technical Standards • UNI EN 12449, 2001. Seamless, round tubes for general purposes. • UNI EN 1057, 2006. Seamless, round copper tubes for water and gas in sanitary and heating applications. • UNI EN 12735-1/2, 2008. Seamless, round copper tubes for air conditioning and refrigeration. • UNI EN 13348, 2008. Seamless, round copper tubes for medical gases or vacuum. • UNI EN 12415. Seamless, round copper tubes for heat exchangers. • UNI EN 723, 1998. Combustion method for determination of carbon on the inner surface of copper tubes or fittings. • ISO 8491, 2005. Metallic materials – Tube bend test. 6/20Alessia Mentella - alessia.mentella@unicas.it
  7. 7. 9 Nono Convegno Torino, 7-9 Settembre 2009 ROTARY-DRAW BENDING Free Bending: configuration of the tools OD t OD 2 BF = = RM OD t ⋅ RM 7/20Alessia Mentella - alessia.mentella@unicas.it
  8. 8. 9 Nono Convegno Torino, 7-9 Settembre 2009 ROTARY-DRAW BENDING Free bending: process limits 1. Thinning at the extradoss fo the bend 2. Flattening at the extradoss of the bend 3. Collapse of the extradoss of the bend 2 3 8/20Alessia Mentella - alessia.mentella@unicas.it
  9. 9. 9 Nono Convegno Torino, 7-9 Settembre 2009 ROTARY-DRAW BENDING Free bending: quality indicators ODZ − ODX #Flex: number of curvature O% = ⋅100 changes in each cross section. OD A0 − A A% = ⋅100 A0 MD0 − HD HD% = ⋅100 SEC-45° - α=π/2 MD0 4A HD = P 9/20Alessia Mentella - alessia.mentella@unicas.it
  10. 10. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS Preliminay results with standard tools Difficulty Geometrical input data and ratios Results factor OD t RM OD/t RM/OD BF O% HD% A% #Flex 8 1 22 8.0 2.8 2.9 2.5 19.2 2.4 1 8 1 14 8.0 1.8 4.6 7.0 22.2 7.8 0.5 6 0.75 10 8.0 1.7 4.8 7.6 22.7 8.7 0.5 E 8 1 12 8.0 1.5 5.3 9.5 24.4 11.3 1 A 9.52 0.67 25 14.2 2.6 5.4 4.9 20.2 4.0 1 S 8 0.5 22 16.0 2.8 5.8 4.7 20.1 3.8 0.5 Y 7.2 0.7 12.5 10.3 1.7 5.9 7.8 22.1 7.7 1 9.52 0.8 15 11.9 1.6 7.6 11.4 24.2 10.8 1 8 0.5 14 16.0 1.8 9.1 11.5 23.4 9.0 1 D 12 0.75 18 16.0 1.5 10.7 I 9.52 0.67 12.5 14.2 1.3 10.8 F 15 1 19.5 15.0 1.3 11.5 F 16 0.9 24 17.8 1.5 11.9 I 18 1 27 18.0 1.5 12.0 C 12.7 0.7 18 18.1 1.4 12.8 U 18 1 23.4 18.0 1.3 13.8 OD t OD 2 L 22 0.9 35 24.4 1.6 15.4 BF = = T 18 0.7 27 25.7 1.5 17.1 RM OD t ⋅ RM 10/20Alessia Mentella - alessia.mentella@unicas.it
  11. 11. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS Modified pressure and bending die 11/20Alessia Mentella - alessia.mentella@unicas.it
  12. 12. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS FEM model description 4-nodes shell elements Cu-DHP R220 with 5 integration points σ(εp)=K(ε0+ εp)n Material (annealed) throughout the thickness Young’s modulus E [MPa] 110000 Elongation A% 0.6 Tensile strenght Rm [MPa] 220 Elastic strain ε0 0.0003027 Initial Yield stress σ0 [MPa] 33.310 Ultimate tensile stress σf [MPa] 336 Hardening exponent n 0.315 Strenght coefficient K [MPa] 426.07 Poisson’s ratio ν 0.343 Density ρ 7.85E-09 CONTACT Contact Interface Static f. c. Dynamic f. c. • Surface to surface Tube/Pressure 0.57 0.35 • Coulomb friction model and bend dies Tube/Wiper die 0.30 0.15 Tube/Clamp die 1.99 1.99 12/20Alessia Mentella - alessia.mentella@unicas.it
  13. 13. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS Experimental validation of the FEM model OD t RM BF (mm) (mm) (mm) 18 1 27 12 0° 90° 45° SECTION O%SIM O%EXP 0° 10% 9.4% 45° 18.3% 22.2% 90° 4.6% 5.3% 13/20Alessia Mentella - alessia.mentella@unicas.it
  14. 14. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS Experimental validation of the FEM model 176.4 mm2 90° OD t RM (mm) (mm) (mm) 0° 45° 16 0.9 24 123.4 mm2 SECTION O%SIM O%EXP 0° 10.9% 9.4% 45° 18.6% 17.5% 90° 4.6% 5.6% 14/20Alessia Mentella - alessia.mentella@unicas.it
  15. 15. 9 Nono Convegno Torino, 7-9 Settembre 2009 DESIGN OF COMPUTER EXPERIMENTS Results with modified pressure and bending dies Configuration 0 Configuration 1 Configuration 2 RE=RM RE=RM+0.5 RE=RM+0.5 Standard pressure-die Retracted pressure-die Milled pressure-die BF O% HD% A% #Flex O% A% HD% #Flex O% A% HD% #Flex 7.6 11.4 24.2 10.8 1 11.4 9.26 23.6 0.5 11.6 11.15 24.3 1.0 9.1 11.5 23.4 9.0 1 12.1 7.23 23.1 1.25 11.2 9.02 23.3 1.0 10.7 18.3 27.2 14.6 1.75 17.3 11.7 25.8 1.25 17.4 13.9 26.7 1.5 10.8 19.6 28.3 16.4 2.5 21.3 15.2 28.1 2 18.6 15.6 27.7 2.25 11.5 20.9 28.9 17.2 2.5 19.8 14.7 27.7 2 20.1 16.5 28.4 2.25 11.9 19.5 27.6 14.9 2.25 18.7 12.2 26.3 1.75 18.6 14.3 27.1 2 12.0 19.7 27.7 15.1 2.75 18.3 12.1 26.2 2.25 18.1 14.2 27.0 2.25 12.8 21.8 29.0 16.7 2.25 22.6 14.2 27.8 1.25 20.4 15.7 28.1 1.75 13.8 25 31.1 19.7 2.25 27.7 19.3 31.2 2.75 23.9 18.8 30.4 2.25 15.4 25.3 30.4 18.0 2.5 22.6 15.0 28.5 2 23.7 17.0 29.5 2.5 17.1 29.5 32.9 21.2 3 severe wrinkling 27.7 19.8 31.8 2.75 15/20Alessia Mentella - alessia.mentella@unicas.it
  16. 16. 9 Nono Convegno Torino, 7-9 Settembre 2009 MODELLING AND IMPROVING THE QUALITY OF THE SECTION Correlation analysis among the quality indicators and development of a unique estimator OD/t has a very limited OD t OD 2 impact on the quality of OD t OD 2BF = = the cross section, and BFnew = = RM OD RM ⋅ t virtually no effect in the (RM OD ) RM 1.5 ⋅ t 0.5 3 “easy” part of the plan. With respect to the newly proposed factor BFnew, a new index Qcs, calculated as a linear combination of the four considered parameters, has been developed: Qcs = β1 ⋅ O % + β 2 ⋅ A% + β 3 ⋅ HD % + β 4 ⋅# Flex βi ≥ 0 ∀i = 1...4 16/20Alessia Mentella - alessia.mentella@unicas.it
  17. 17. 9 Nono Convegno Torino, 7-9 Settembre 2009 MODELLING AND IMPROVING THE QUALITY OF THE SECTION Correlation analysis among the quality indicators and development of a unique estimator 3.5 30 3.0 RM/OD 25 OD/t 2.5 20 Rm/OD 2.0 OD/t 15 1.5 10 1.0 0.5 5 0.0 0 0 5 10 15 20 25 Qcs 17/20Alessia Mentella - alessia.mentella@unicas.it
  18. 18. 9 Nono Convegno Torino, 7-9 Settembre 2009 MODELLING AND IMPROVING THE QUALITY OF THE SECTION Correlation analysis among the quality indicators and development of a unique estimator Qcs = β1 ⋅ O % + β 2 ⋅ A% + β 3 ⋅ HD % + β 4 ⋅# Flex The best fit linear regression model (R2=0.972) between Qcs and BFnew is obtained when β1 = 0.218; β 2 = 1.286; β 3 = 0; β 4 = 0.776 r O% A% HD% #Flex QCS O% 1 Qcs = A%+ # Flex A% 0.976 1.000 (β1 = 0; β 2 = 1; β3 = 0; β 4 = 1) HD% 0.991 0.995 1 #Flex 0.924 0.871 0.900 1 QCS 0.9833 0.9981 0.997 0.900 1 18/20Alessia Mentella - alessia.mentella@unicas.it
  19. 19. 9 Nono Convegno Torino, 7-9 Settembre 2009 MODELLING AND IMPROVING THE QUALITY OF THE SECTION Correlation analysis among the quality indicators and development of a unique estimator 35 O% 2 R = 0.959 18 30 A% Flex 16 R2 = 0.858 Difficulty Factors Qcs 2 R = 0.949 14 BFnewQuality Indicators 25 HD% 12 BF 2 R = 0.970 20 10 2 R = 0.967 conventional 8 15 tooling 6 modified tooling R2 = 0.970 4 10 2 5 0 2 R = 0.781 0 5 10 15 20 25 0 QCS 0 2 BF new 4 19/20Alessia Mentella - alessia.mentella@unicas.it
  20. 20. 9 Nono Convegno Torino, 7-9 Settembre 2009 MODELLING AND IMPROVING THE QUALITY OF THE SECTION Conclusions• NO INTERNAL MANDREL for copper tubes with round cross section for hydro-thermo-sanitary applications. strong tendency of the tube to collapse ovalization and reduction of area aesthetical problems and head losses• A new index can be chosen, QCS=A%+#Flex, which synthetically and effectively represents all quality parameters of the cross section.• A new bending difficulty factor has been introduced, Bfnew , which shows a good correlation with the traditional quality parameters and an excellent correlation to QCS.• In order to enhance the quality of the cross section of the bent tube, it is necessary to re- design the tooling configuration, for difficult to bend tubes (BFnew>2); for easy to bend tubes (BFnew<2), the standard tooling must be preferred. 20/20Alessia Mentella - alessia.mentella@unicas.it
  21. 21. Nono Convegno 9 Torino, 7-9 Settembre 2009Tube Free Bending: a new index for the control of the cross section quality Alessia Mentella Matteo Strano Roberto Gemignanialessia.mentella@unicas.it matteo.strano@polimi.it roberto.gemignani@blm.it Stefano Farina stefano.farina@blm.it THANK YOU FOR YOUR ATTENTION!

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