Design And Strength Analysis Of Self-locking Structure Of Replaceable Bit

In metal cutting,drilling is still the most widely used hole processing method,and the tool used more frequently in drilling is still the twist drill,but the traditional twist drill has some disadvantages,such as the need to reposition the tool after wear,time-consuming and laborious cutting edge polishing,and high material cost.The replaceable bit is divided into cutter head and cutter rod.The cutter head is made of carbide with good cutting performance,while the cutter rod is made of ordinary alloy steel with poor mechanical performance and cheap processing.The cutter head and cutter rod of the replaceable drill head are connected by selflocking,which can realize the quick clamping and positioning of the cutter head.Moreover,the same cutter head can be installed with several cutter heads of different sizes.The cutter head can only be replaced after the failure of the cutter head,which saves the material cost of the drill head.At the same time,the replaceable bit adopts the internal cooling method,and the internal cooling hole is made in the bit,which greatly improves the heat dissipation and chip discharge performance of the bit.Enterprise production can be removable nipple bit though now has many advantages,but there are some problems,such as cutting force mutations,bit broken,the blade segment,such as loss of the blade when cutting head loss not only affects the surface quality of hole,but also greatly reduces the production efficiency,so it is necessary to design the structure of a reliable guarantee segment in the process of return will not fall off.In this paper,the existing problems in the connection structure of the replaceable bit in the enterprise are analyzed first,and then the replaceable bit which can prevent the cutting head from falling off through dovetail groove structure is designed by referring to the characteristics of the new type of replaceable bit in foreign countries.Because the structure of the connection of the replaceable bit has changed,two kinds of replaceable bit with self-locking structure have been designed.Because the structure of self-locking bit is the most dangerous,the newly designed replaceable bit has self-locking structure for strength analysis.The designed replaceable bit was modeled using 3D software Solid Works,and then the drilling process was simulated in finite element analysis software Advant Edge FEM,and the cutting force in the simulation results was extracted.The cutting force obtained is used in the strength analysis of the newly designed replaceable bit self-locking structure by the finite element analysis software ANSYS to analyze the steady state safety of the self-locking structure.Of design can be removable nipple bit cutting test and verify the reliability of self-locking structure,optimized scheme was designed using orthogonal experiment method,analysis of eccentricity and eccentric circle radius of self-locking structure strength,the influence of the parameters obtained through the analysis of the poor to the influence degree of the self-locking structure strength and rule,finally get more secure self-locking structure.By analyzing the dynamic characteristics of the optimized new replaceable bit,the resonance frequency of the bit is determined to provide guidance for its application.The results show that the finite element analysis software can shorten the design cycle and reduce the design cost.At the same time,it can also provide some reference for the design of other bits in the future,and it is hoped that the design idea and analysis method can be applied to the design of other mechanical structures.