Design Of Wear-resistance Test Platform Of Sealing Element And Contact Stress Analysis In Shield Tunneling Machine

In the process of working on the slurry shield machine,in order to prevent the intrusion of external liquid materials such as soil and slurry,a variety of seals are required to ensure the normal operation of the equipment.As the shield machine develops toward the direction of super large diameter,long distance and large depth,the seal is subjected to high fluid pressure.At this stage,the depth of the shield machine will reach 150-200 meters,and the external fluid pressure will reach 1.5-2MPa.In order to achieve this goal,higher requirements are placed on seal materials,mechanical behavior and wear resistance.At the present stage,people mainly use finite element to simulate the contact stress,shear stress and Von-Mises stress of rubber seals,and have obtained many research results,but few people fit the parameters of maximum contact stress,compressibility and fluid pressure into a functional relationship.The parameters are fitted to a functional relationship,which can be used to guide the selection of the minimum compression ratio.The wear failure of the rubber seal in the dynamic seal is related to the sealing effect of the shield machine.When performing the rubber seal wear test,the conventional shifting and load-changing tests are generally performed,and few people perform the wear test under different fluid pressures because the test platform capable of achieving wear resistance of the rubber seal ring is rare.At the same time,in order to improve the service life of shield machine seals,it is necessary to master the wear failure rules under different speeds and fluid pressures and the choice of rubber materials.But there are few reports in the literature.This paper analyzes the minimum compression ratio of rubber seals to meet sealing requirements.In addition,few people have studied the morphology of the wear surface based on the O-ring seal dynamic friction and wear test.To this end,this paper firstly uses ANSYS software to model the O-ring seal of the slurry sealer static seal,and analyzes the relationship between the O-ring seal contact stress and compression ratio,fluid pressure,friction coefficient and hardness.The contact stress under rubber hardness is a function of compression ratio and fluid pressure.I developed a wear-resistant test platform for shield machine seals,and realized the friction and wear test of rubber seals under constant speed and constant pressure.On this basis,the wear behavior test platform was used to study the wear behavior of nitrile rubber O-rings under certain compression ratio and fluid pressure.It was found that the wear and friction torque of O-rings in water and slurry media.As the fluid pressure increases,the wear of the rubber increases due to the presence of sand particles in the mud,making the wear amount and friction torque larger than the aqueous medium.Through the research of this thesis,the minimum compression ratio range of rubber seals under different fluid pressures will be given.The wear failure of rubber seals under different fluid pressures,rotational speeds and working media and the selection method of materials will be given.The development of rubber seals of the shield machine is promoted,and at the same time,it is helpful to extend the service life of the rubber seal ring of the slurry shield machine.