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Study on Burning Failure Mechanism of Friction Couples of the InfinitiveStage-Clutch in a Shield Machine′s Cutterhead
(1 Provincial Key Laboratory of Food Logistics Equipment ＆ Technology, Zhejiang University of Science and Technology, Hangzhou 310023; 2 College of Engineering, University of Florida, Gainesville 32611, U.S.A.; 3 State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027)
Abstract The thermal load field between the friction couples of the 300 kW infinitive-stage-clutch used in a shield machine′s cutterhead, which is composed of copper-based powder metallurgy friction plates and 22MnB5 steel dual-discs, were calculated according to the heat conduction theory combined with the engineering thermodynamics method. The temperature field distribution T(r) along the friction couple′s surfaces was obtained, as well as the week thermal stress σ θ distribution and the radial thermal stress σr distribution along the radial direction of the dual-steel-disc′s surface. Two conclusions were drawn from those distribution curves: that T(r) , σθ and σr are clearly heterogeneous in the radial direction, and that σθ , being larger than σr in an order of magnitude, should be contributed to the deformation of the dual-steel-disc. It can theoretically be concluded from further analyses that the friction couple would be under the critical sliding friction condition if the speed difference Δω falls to 1.37 π rad /s; the material layer of the powder metallurgy friction plate might be burned or damaged because of T(r) when the friction couple repeatedly runs or works for a long time under the critical sliding friction condition, and the dual-steel-disc might be converted from a plane into a shallow dish in the axial direction as a result of σθ . By the experiments, the failure mechanisms and modes of the powder metallurgy friction plate and it′s dual-steel-disc are proved and the recommended values, complying with the quantitative definition indicators under the actual critical sliding friction condition during design and operation of the infinitive-stage-clutch in the shield machine′s cutterhead, are proposed.
Abstract：
The thermal load field between the friction couples of the 300 kW infinitive-stage-clutch used in a shield machine′s cutterhead, which is composed of copper-based powder metallurgy friction plates and 22MnB5 steel dual-discs, were calculated according to the heat conduction theory combined with the engineering thermodynamics method. The temperature field distribution T(r) along the friction couple′s surfaces was obtained, as well as the week thermal stress σ θ distribution and the radial thermal stress σr distribution along the radial direction of the dual-steel-disc′s surface. Two conclusions were drawn from those distribution curves: that T(r) , σθ and σr are clearly heterogeneous in the radial direction, and that σθ , being larger than σr in an order of magnitude, should be contributed to the deformation of the dual-steel-disc. It can theoretically be concluded from further analyses that the friction couple would be under the critical sliding friction condition if the speed difference Δω falls to 1.37 π rad /s; the material layer of the powder metallurgy friction plate might be burned or damaged because of T(r) when the friction couple repeatedly runs or works for a long time under the critical sliding friction condition, and the dual-steel-disc might be converted from a plane into a shallow dish in the axial direction as a result of σθ . By the experiments, the failure mechanisms and modes of the powder metallurgy friction plate and it′s dual-steel-disc are proved and the recommended values, complying with the quantitative definition indicators under the actual critical sliding friction condition during design and operation of the infinitive-stage-clutch in the shield machine′s cutterhead, are proposed.
CHEN Ning- 1 Derek Chen 2 Qiu-Min-Xiu- 3 Weng-Wei-Bing- 1 Xu- Xing
.Study on Burning Failure Mechanism of Friction Couples of the InfinitiveStage-Clutch in a Shield Machine′s Cutterhead[J] MODERN TUNNELLING TECHNOLOGY, 2016,V53(5): 123-130
2016, Vol. 53 