Heat Treatment Optimization Of Hob Ring Material For Shield Tunneling Machine

With the rapid urbanization of our country,more and more cities pay attention to the construction of urban rail transit.Shield tunneling is the most common way to build subway tunnels in urban rail transit.The shield machine uses the tool to cut the stratum to realize the excavation.In the construction process,it will face all kinds of bad geological conditions,which is easy to cause the tool damage.It is of great significance to study the effective method to improve the life of cutter ring of shield machine hob for improving engineering efficiency and reducing construction cost.After consulting the relevant data,it can be seen that by optimizing the heat treatment process of the material can change the material properties and achieve the purpose of improving the life of the cutter ring.In this thesis,5Cr5 Mo WVSi alloy steel was selected as the test material.By establishing a virtual simulation platform for heat treatment,the cloud map of the temperature distribution,material structure composition and hardness data of the tool during the implementation of the optimal heat treatment process was analyzed.Heat treatment test was carried out by orthogonal test method,and the best heat treatment process parameters of the tool were obtained according to the performance test of the tool.On this basis,the tool wear model is established by using the actual wear amount of the tool in the shield construction process.The conclusions are as follows:(1)Through the establishment of the virtual heat treatment simulation platform,multiple sets of heat treatment simulation were carried out on the 5Cr5 Mo WVSi material cutter ring,the optimal heat treatment process was obtained,and the cloud map of temperature,structure and hardness distribution was obtained to provide reference for the test.(2)By testing the material properties under different heat treatment processes,analyzing the hardness,toughness and metallographic composition,the best heat treatment process parameters were obtained.The results show that when the quenching temperature is 1030 ℃ and the tempering temperature is 560 ℃,the hardness and toughness can meet the construction requirements.Compared with the heat treatment results of DC53 steel,the properties of 5Cr5 Mo WVSi are better than those of DC53 steel.By comparing the simulation results,the relative error between the material hardness simulation results and the heat treatment test results is 1.3%,which verifies the accuracy of the test.It provides an effective way to further optimize and improve the mechanical properties of tool materials.(3)The cutter ring made based on the above heat treatment process parameters has been used in engineering tests.By testing the wear amount,it is found that the5Cr5 Mo WVSi hob ring has less wear and longer life than the DC53 hob ring,and both wear are normal.On the basis of the stress analysis of the tool and the actual wear of the tool,the prediction model of the tool wear is established.The results show that the proportion of abrasive wear to tool wear is the largest,followed by adhesive wear and fatigue wear is the least.This conclusion has found the solution direction for reducing tool wear.