Inspire industry to make more with less

Transcription

1 Inspire industry to make more with less Gear manufacturing, more than compaction and sinter PM World Congress Hamburg Germany, 2016 Anders Flodin 1 Höganäs AB - Anders Flodin

2 Outline Scope of Consortium M32 project Synchronisers Joining Heat treatment Wear Bearings NVH Optimisation 2 Höganäs AB - Anders Flodin

3 Scope of Consortium M32 Project Vicura/AVL to redesign a typical European modern manual transmission for powder metal gears Reduce weight Minimise transmission error (meaning noise) Design for reduced stress levels Building PM parts manufacturers PM equipment supplier PM material supplier 3 Höganäs AB - Anders Flodin

4 Prototyping from our Partners Other project contributions 4 Höganäs AB - Anders Flodin

5 Scope of Consortium M32 Project Vicura/AVL to redesign a typical European modern manual transmission for powder metal gears Reduce weight Minimise transmission error (meaning noise) Design for reduced stress levels Building PM parts manufacturers PM equipment supplier PM material supplier Testing Contact pattern Durability Vibration 5 Höganäs AB - Anders Flodin

6 Scope of Consortium M32 Project And build into demo car SAAB test track day CTI Booth CTI test drive 6 Höganäs AB - Anders Flodin

7 Synchroniser Gear Vital part of the loose gears How to get it onto the PM gear 7 Höganäs AB - Anders Flodin

8 Welding of PM Many variables! Laser Electron beam -vaccum PM/PM PM/Steel Process history of PM Carbon level Spot diameter Filler wire Can brazing be an alternative? Smart joining through geometrical interlocking (Think Spline!) Glue! 8 Höganäs AB - Anders Flodin

9 Hardness [HV0.1] Case Hardening of PM Alloying elements are necessary (unfortunately) Carbon can not fix low alloy-content Right shape of the hardness curve 900 Distaloy AQ- mn 4,5 800 Flank 700 Root HV Distance from the Surface[mm] 9 Höganäs AB - Anders Flodin

10 What are we looking for? For gears: Rule of Thumb Cd= *Modulus Carbon levels as low as possible Higher carbon levels reduces residual compressive stress due to volume expansion At 0.6% C residual stress is 0-50MPa At 0.2% it can be 350 Mpa Not to hard (not more than 850HV0.1) grinding wheel fails Hardness plateau at surface for grinding stock Core hardness around HV 10 Höganäs AB - Anders Flodin

11 Hardness HV0.1 Hardness HV0.1 Controlling Heat Treatment Hardness profile Astaloy 85Mo+0,3%C Distance from Surface [mm] 900 Same Cd different result Distance from Surface [mm] 11 Höganäs AB - Anders Flodin

12 Simulated Wear after full Durability Cycle for 6 Speed gear 8-10 Microns of wear depth, less than or same order as micro modifications Same as tolerance window for the crowning Wear depth Left flank (worn) Right flank 12 Höganäs AB - Anders Flodin

13 Wear after full Durability Cycle for 6 Speed Gear Before After 13 Höganäs AB - Anders Flodin

14 Bearings It is not only the flanks that has to carry load. Needle bearings in the bore carry high quasi static loads during operation. If wear in the bore is a problem a needle bearing with outer raceway can be used. Important to think about for planetary gears that roll on the bearings under load. 14 Höganäs AB - Anders Flodin

15 Bearing Loads Calculation M=230 Nm Calculation M=320 Nm Fr= 1804 N Fr= 2509 N Fa= 3233 N Fa= 4498 N Case Mtilt [Nm] p [MPa] Descr. Case Mtilt [Nm] p [MPa] Descr Radial force only Radial force only 2 112, Radial force and tilt moment at single contact 2 156, Radial force and tilt moment at single contact 3 104, Radial force and tilt moment at pitch diameter 3 144, Radial force and tilt moment at pitch diameter 15 Höganäs AB - Anders Flodin

16 Surface Roughness Finish rolling gives: Very smooth surfaces Tribologically superior surface to grinding Quiet surface in rolling/sliding contacts Cost efficient alternative to Shaving Roll in lead crowning and mods Rolled Shaved As sintered, die surface 16 Höganäs AB - Anders Flodin

17 Speed [rpm] Torque Nm Results Vibration/NVH Consortium All but one gear showed improved vibration characteristics. The one gear that showed higher vibration levels was out of spec. geometrically Höganäs All gears passed vibration testing with lower levels than stock transmission reference 7000 Speed ramps Speed High Torque "Low" Torque "High" Time[s] 17 Höganäs AB - Anders Flodin

18 NVH 3 FZG C gears (driven gear, the big one) PM 7.2 density Multi density (not sure which densities we have) ZF solid steel FZG gear High dens High dens Low dens Low dens 18 Höganäs AB - Anders Flodin

19 Results The results clearly show that the vibration losses of test object denoted Gear 2 are higher than those of Gear 1 and Gear 3. In terms of damping in % of critical damping Gear 2 has ca 50 % higher losses. Gear 1=Steel Gear 2=Multi dens PM Gear 3=PM Third-octave band Axial, damping in % of critical Radial, damping in % of critical Gear Gear Gear

20 Optimisation Stress reduction in root increases design space More optimal solution can be selected Decreases shock load stress 20 Höganäs AB - Anders Flodin

21 PM is Unique Design Freedom Design for contact stress reduction Manufacturing window larger for PM compaction 21 Höganäs AB - Anders Flodin

22 Outlook Tear down of 3 new platforms with the trending technologies Analysis of current PM content Analysis of competitive technologies whom are we losing market to? Analysis of future growth potential for PM in Automotive in these times of hybridisation and downsizing. 22 Höganäs AB - Anders Flodin

23 23 Höganäs AB - Anders Flodin Thank you!