Analysis of Interference of Alloy Tooth Assembly of Down-the-hole Hammer
Down-the-hole hammer(DTH)impactor is widely used in all kinds of hole forming operations with high drilling efficiency and good quality.In the process of the impactor,the bit is affected by the piston's high frequency impact and the formation's reverse torque,and the tooth loss is the main failure problem.According to the tooth loss failure of the bit in a limestone mine,the failure mechanism of alloy tooth loss was analyzed.Based on thick-walled cylinder theory,Tresca yield condition and full increment theory,the ultimate interference quantity of alloy tooth was analyzed and calculated,and the reasonable range of interference quantity was determined.The process of alloy tooth interference assembly was simulated and analyzed by finite element simulation.The research shows that the main cause of tooth loss is that the fixing force is less than the tooth removal force due to insufficient interference.Through the analysis and comparison of theoretical calculation and simulation results,the optimal interference quantity of alloy tooth assembly is 0.065 mm,which can effectively prevent tooth loss and tooth removal.Compared with the previous generation,the service life of the improved bit is greatly extended after it is put into use,which has certain guiding significance for the design and application of the subsequent drill hole impactor.
down-the-hole hammeralloy tooth assemblymagnitude of interferencepercussive drillsimulation calculation
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