Abstract
The dynamic behaviour of a machine tool (MT) directly influences the machining performance. The adoption of lightweight structures may reduce the effects of undesired vibrations and increase the workpiece quality. This paper aims to present and compare a set of hybrid materials that may be excellent candidates to fabricate the MT moving parts. The selected materials have high dynamic characteristics and capacity to dampen mechanical vibrations. In this way, starting from the kinematic model of a milling machine, this study evaluates a number of prototypes made of Al foam sandwiches (AFS), Al corrugated sandwiches (ACS) and composite materials reinforced by carbon fibres (CFRP). These prototypes represented the Z-axis ram of a commercial milling machine. The static and dynamical properties have been analysed by using both finite element (FE) simulations and experimental tests. The obtained results show that the proposed structures may be a valid alternative to the conventional materials of MT moving parts, increasing machining performance. In particular, the AFS prototype highlighted a damping ratio that is 20 times greater than a conventional ram (e.g., steel). Its application is particularly suitable to minimize unwanted oscillations during high-speed finishing operations. The results also show that the CFRP structure guarantees high stiffness with a weight reduced by 48.5%, suggesting effective applications in roughing operations, saving MT energy consumption. The ACS structure has a good trade-off between stiffness and damping and may represent a further alternative, if correctly evaluated.
Highlights
The dynamic behaviour of a machine tool (MT) plays a crucial role in satisfying the main machining requirements, like high-speed operations, precision in axis positioning, and the capability to quickly remove a high quantity of workpiece material [1]
The results show that the CFRP structure guarantees high stiffness with a weight reduced by 48.5%, suggesting effective applications in roughing operations, saving MT energy consumption
This paper aims to evaluate the static and dynamic performances of a set of MT structures made of hybrid materials
Summary
The dynamic behaviour of a machine tool (MT) plays a crucial role in satisfying the main machining requirements, like high-speed operations, precision in axis positioning, and the capability to quickly remove a high quantity of workpiece material [1]. These performances are directly related to the materials used in MT construction. Forces acting on the MT structure during motion represent a serious limitation for the precision and productivity and, they are evaluated during machine design and material selection [3,4]. Structural deformations may lead to unwanted displacements of the tool tip point (TTP), causing undesired deviations and degradations of surface quality during finishing
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