Development Of Damage Simulation Test Bench For Shield Main Bearing

Shield Tunnel Boring Machine is a green,efficient and safe tunnel boring equipment,which has a huge market prospect.The main bearing is one of the key components of the cutter head drive system of the shield machine,its bearing capacity and service life are related to the construction progress of the project.Statistically,up to 95% of the main bearings are damaged in advance without reaching the design life in service,and only 5%can meet the design requirements.Due to the long-term operation under the conditions of compound load and impact load,as well as the influence of many factors such as poor lubrication,invasion of impurities and improper use,etc.,some forms of damage to the main bearing could have occurred.Once the main bearing is damaged during the construction process,leading the shield machine to break down,it is difficult and time-consuming to replace the main bearing,which will delay the construction schedule and cause huge economic loss.For ensuring the safety and stable operation of the shield machine,it is necessary to study the relationship between the signal generated when the shield main bearing is damaged and its damage form,which is of great significance both in theoretical and engineering guidance for the condition monitoring and fault warning of the main bearing.This paper studies the operating conditions of the main bearing and determines the main technical parameters of the test bench based on the principle of shrinkage experiment.Based on the technical parameters of the test bench,the design of mechanical structure,finite element analysis,control system and hydraulic loading system were carried out.Finally,the assembly and commissioning of the test bench are completed.The main research contents and results of the paper are as follows:1.Take the earth pressure balance shield machine as the reference object,combined with the installation form of the main bearing,analyze the stress of the main bearing.Using the experimental theory of shrinkage ratio,the main technical parameters of the test bench were calculated.Based on the analysis of the bearing capacity of the main shaft and the technical parameters of the test bench,the overall design plan of the test bench and the setting of the simulated working conditions are proposed.The three-dimensional modeling software SOLIDWORKS was used to complete the design,modeling and assembly of the mechanical structure of the test stand.2.According to the overall design plan of the test bench,the main bearing,motor and reducer that needed are selected,and the main drive shaft of the test bench is checked by theoretical calculation.The calculation results show that the main drive shaft meets the design requirements;and the loading device of the test bench is designed to meet the requirements of simulated working conditions.3.The internal stress and deformation of the prototype main bearing and the main bearing to be tested are analyzed by commercial finite element software ABAQUS to obtain the simulation results.The results show that the location and trend of the stress and deformation inside the two are identical,indicating that the test bench can well simulate the load of the spindle.the permanent seat of the main bearing and loading disc are checked for strength to meet the design requirement.Considering the influence of external loads such as motor vibration on the main structure during the operation of the test bench,the main structure of the test bench was dynamically calculated,and corresponding measures were proposed for the safe operation of the test bench.4.The next step is to design the control system and hydraulic system.According to the experimental requirements,the control system hardware is selected,and the main circuit diagram and control circuit diagram of the test bench are designed.The control program including pressure sensor data collection,control converter switch,the main motor controller,controllers of oil pump motor and hydraulic pressure cylinder,etc.are written in Lab VIEW.According to the experimental requirements and the size of the simulated load,the hydraulic station is selected and the hydraulic cylinder model is determined.5.The components of the test bench are manufactured and assembled,meanwhile,the controller and hydraulic loading system are installed and debugged.The debugging results show that the test bench is stable,safe and reliable,and meets all design indexes.