Model-based cutting prediction for a self-vibratory drilling head - spindle system

• Published in: International journal of machine tools & manufacture Vol. 52; no. 1; pp. 59 - 68
• Main Authors: Forestier, F., Gagnol, V., Ray, P., Paris, H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2012; Elsevier
• Subjects: Applied sciences; Chips; Contact dynamics; Cutting; Cutting parameters; Drilling; Drilling stability; Drives; Dynamics; Engineering Sciences; Exact sciences and technology; Fundamental areas of phenomenology (including applications); High-speed vibratory drilling; Mathematical models; Mechanical engineering; Mechanical engineering. Machine design; Mechanics; Physics; Receptance coupling; Shafts, couplings, clutches, brakes; Solid mechanics; Spindles; Structural and continuum mechanics; Vibration; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...); Contact dynamics; High-speed vibratory drilling; Receptance coupling; Drilling stability; Great depth; Drill; High speed machine; Stability criterion; Vibration test; Modeling; Vibration machining; Finite element method; Machine tool; Self excitation; High speed; Shaft; Lubrication; Transfer function; Chip separation; Machine tool spindle; Production process; Deep drilling; Productivity; Operating conditions; High pressure; Longitudinal vibration; Frequency characteristic
• ISSN: 0890-6955; 1879-2170
• DOI: 10.1016/j.ijmachtools.2011.09.001

The drilling of deep holes remains an unsatisfactory machining operation due its limited productivity. This manufacturing process requires the chips to be evacuated through the use of retreat cycles and high-pressure lubrication, which is problematic both for productivity and the respect of the environment. An alternative response to the chip evacuation problem is the use of a vibratory drilling head which enables the chip to be split thanks to the drill's axial vibration. The high-speed drilling operation requires specific cutting conditions to be determined in order to maintain self-excited axial vibration throughout the drilling process. The prediction of adequate cutting conditions is determined on the basis of the frequency characteristics of the spindle/self-vibratory drilling head and the dynamics of the cutting process. It can be expressed in terms of a specific stability diagram indicating the zone of stable self-excited axial vibration. The aim of this study is to develop a high-speed spindle/drilling head/tool system finite element model to evaluate the system's dynamic characteristics and the adequate cutting conditions allowing stable self-excited axial vibration. The model is elaborated on the basis of rotor dynamics prediction, and takes into account the interfaces between system components, using the receptance coupling method. Using the model, adequate cutting conditions are determined by integrating the model-based tool tip transfer function into the chatter vibration stability approach proposed by Budak and Altintas. The simulated results are validated by performing vibration and drilling tests. The proposed model can be used to accurately evaluate the dynamic performance of the spindle/self-vibratory drilling head and can also be used to design an optimised spindle/drilling head for a given drilling process. ► We present the development of a (spindle – self vibratory drilling head) dynamic model. ► It takes into account rotor dynamics effects, bearings and interfaces behaviour. ► Validation is conducted by comparing the numerical with experimental results. ► Optimal settings of the system are predicted by specifics stability lobe diagrams.