Noise and Vibration Control in Metal cutting
Noise and vibration problems are common in industrial and domestic applications. A frequent problem in the manufacturing industry today is the vibrations induced by metal cutting, e.g. turning, milling and boring operations. Vibrations in boring operations or internal turning operations are usually inevitable and constitutes large problem in the manufacturing industry.
Metal cutting operations
The tool vibrations in metal cutting affect the result of the machining, in particular the surface finish. Further more, the tool life is correlated with the amount of vibration and the acoustic noise introduced.
The noise level is sometimes almost unbearable. Vibration in boring operations or internal turning operations is usually inevitable. More generally, vibration occurs when metal cutting is carried out with advanced cutting data, e.g. material removal rates considered to be high, or in so-called hard-to-cut materials, e.g. high strength, thermal resistant superalloys. The demands on machining tolerances and especially the productivity continuously increases. Also, the rapid technological development continuously produces demands on the machining of parts to complicated geometrical shapes with respect to metal cutting.
It is well-known that vibration problems in metal cutting operations can be related to the dynamic stiffness of the structure of the machinery and workpiece material. The vibration problem may be solved in part by proper machine design which stiffens the machine structure.
The aim of the project is to reduce the vibration problems in metal cutting based on active control technologies and boring bars with embedded actuators. The active control system for metal cutting is based on a patented design of active tool holders or boring bars, i.e. tool holders with embedded actuators and vibration sensors (integrated actuators and vibration sensors), and feedback control theory. The performance of an active boring bar may be improved significantly by moving the placement of the actuator compared to the position given by the current design method. The fact that there exist different standard clamping designs for e.g. boring bars further complicates the design of active boring bars. The design of the clamping influence the modal properties of a clamped boring bar, i.e. the boundary conditions on applied the clamped end differ between different clamping designs. Another important issue is tool failure in the engagement phase of the cutting edge with the workpiece due to insufficient controller speed. The purpose of this project is the improvement of the design methods for the implementation of an embedded actuator or actuators in a given boring bar and clamping. Another important objective, is to extend the active boring bars towards increased length to diameter ratio or overhang which in turn requires the design method to be improved. It is also intended to develop new faster controllers.