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A gun drill mechanics model analysis

3 mars 2022 à 0h14   Auto & Moto   Salah Bey   57 vues

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Gun drilling is a process used to produce small-diameter holes at a high depth-to-diameter ratio, beyond what is capable using conventional tooling, especially for difficult-to-machine superalloys such as titanium, Inconel, Monel, etc. Presently, it often incapacitates by low productivity, rapid tool wear, frequent tool breakages, and straightness deviation. This chapter addresses the challenges of tackling these problems by employing game-changing approaches and technologies. Existing research in the advanced gun drilling technologies tends to focus on the choice of drilling parameters. There is little literature available for the cutting mechanics and workpiece deformation, tool geometry, wear and failure mechanism, especially in the deep hole drilling process for superalloys. Consequently, the aim of this chapter is to provide an overview of how the game-changing approaches and technologies for advanced gun drill tool can be explored and utilized.

 

The drilling of deep holes by means of deep hole gun drill is investigated so as to establish the parameters of the guide hole and its production. The rate of change in the load on the tool is proportional to the active length of the primary cutting edge. Assessment of the smoothness of tool insertion on the basis of the rate of change in the load on the tool is proposed.

 

Drilling mechanics model has always been the key and difficult point in the research field of solid carbide gun drill. In this paper, through theoretical analysis and processing experiments, the gun drilling mechanics model of Ti6Al4V titanium alloy is studied. On the one hand, based on the Oxley cutting model and the Johnson-Cook flow stress model, this paper takes Ti6Al4V titanium alloy as the research object and use the “microelement” method to establish the mechanical model of gun drilling, which includes cutting parameters, tool geometric parameters and material mechanical properties. 

 The regenerative mechanism is the main source of chatter vibrations. And it requires that time-delayed terms in model equations should be taken into account. The same mechanism emerges not only in drilling [3-5], but in milling [6], boring etc. The comprehensive review of present state of deep hole drilling modeling was given in [1]. Most authors modeled drill shank using the reduced single degree of freedom system. In this insert gun drill is considered as flexible continuous beam loaded with eccentrically applied cutting force. 

The MF1250/2FL does not require continuous attendance by an operator during operation, and it is capable of drilling many meters before the diamond gun drill needs to be re-sharpened. This gun drilling and milling machine is designed and manufactured to make moulds weighing up to 6 ton, with a diagonal of up to 1900 mm (diameter in rotation within the structure of the machine). This model is equipped with a rotary/tilting table as a standard. This makes it possible to drill complex cooling circuits with compound angle drilling, thanks to the combination of table rotation 360,000 pos/rev and the ±22,5° tilting movement in infinite position.

 

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